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Sample records for excess pore pressure

  1. Evidence for excess pore pressures in southwest Indian Ocean sediments

    SciTech Connect

    Abbott, D.; Menke, W.; Hobart, M.; Anderson, R.

    1981-03-10

    Brown clay cores from the Madagascar and Crozet basins show the following evidence of excess pore pressures: large amounts of flow-in, increasing average sedimentation rate with age, and nonlinear temperature gradients. Additionally, many hilltops in these basins have no visible sediment cover. The bare hilltops may result from periodic slumping caused by excess pore pressures. Calculated excess pore pressures which equal or exceed the overburden pressure were inferred from water fluxes predicted by nonlinear temperature gradients and laboratory permeability measurements by using Darcy's law. Since pore pressures which exceed the overburden pressure are unreasonable, we attribute this discrepancy to laboratory measures which underestimate the in situ permeability. The widespread presence of overpressured sediments in areas of irregular topography provides a process for resuspension of clay-sized particles. This mechanism does not require high current velocities for the erosion of clay and therefore can be applied to many areas where no strong currents are evident. Carbonate-rich sediments from the Madagascar Ridge, the Mozambique Ridge, and the Agulhas Plateau had almost no flow-in and occurred in areas where all topography was thickly draped with sediment, Since the age and tectonic location of the ridges and plateaus preclude water circulation in the basement, we attribute these differences between the brown clay and the carbonate-rich material to an absence of significant excess pore pressures in the plateau and ridge sediments.

  2. Excess pore water pressure due to ground surface erosion

    NASA Astrophysics Data System (ADS)

    Llewellyn Smith, Stefan; Gagniere, Steven

    2015-11-01

    Erosional unloading is the process whereby surface rocks and soil are removed by external processes, resulting in changes to water pressure within the underlying aquifer. We consider a mathematical model of changes in excess pore water pressure as a result of erosional unloading. Neuzil and Pollock (1983) studied this process in the case where the water table initially coincides with the surface. In contrast, we analyze an ideal aquifer which is initially separated from the ground surface by an unsaturated zone. The model is solved using Laplace Transform methods in conjunction with a boost operator derived by King (1985). The boost operator is used to boost the solution (in the Laplace domain) to a frame of reference moving at constant velocity with respect to the original frame. We use our solution to analyze the evolution of the pressure during erosion of the aquifer itself for small and large erosion rates. We also examine the flux at the upper boundary as a function of time and present a quasi-steady approximation valid for very small erosion rates in the appendix.

  3. Modified Newmark method involving excess pore pressure to express unlimited landslide displacement

    NASA Astrophysics Data System (ADS)

    Fukuoka, H.; Tsukui, A.

    2012-12-01

    Newmark method is the most popular approach to assess the displacement of landslides induced by earthquakes using seismic acceleration, slope inclination, and friction parameters. However, this method always shows limited shear displacement no matter how the acceleration is large and duration is long. This is partly because it does not include any pore pressure, especially excess pore water pressure generated under long shear displacement. As shown by series of earthquake wave-form loading undrained ring shear tests by Disaster Prevention Research Institute of Kyoto University, grain crushing or soil skelton collapse can contribute to generation of high excess pore pressure and let the soil to reach liquefaction state ("Sliding surface liquefaction"). Many of unlimited landslide displacement have been revealed that this phenomena must be the key mechanism. In the test series of mixture of silica sands and dry-ice pellets (frozen carbon-dioxide), for studying the mechanism of the gasification of methane hydrates in the submarine landslides which likely to trigger large scale submarine landslides, authors have found linear relationship between log of excess pore pressure ratio (generated pore pressure / initial effective normal stress) and log of shear displacement. By embedding this relation into the Newmark method, unlimited shear displacement can appear under certain slope inclination and exaggerated acceleration. Authors show there is critical slope inclination for unlimited displacement when given acceleration waveform.

  4. Gas Hydrate and Pore Pressure

    NASA Astrophysics Data System (ADS)

    Tinivella, Umberta; Giustiniani, Michela

    2014-05-01

    Many efforts have been devoted to quantify excess pore pressures related to gas hydrate dissociation in marine sediments below the BSR using several approaches. Dissociation of gas hydrates in proximity of the BSR, in response to a change in the physical environment (i.e., temperature and/or pressure regime), can liberate excess gas incrising the local pore fluid pressure in the sediment, so decreasing the effective normal stress. So, gas hydrate dissociation may lead to excess pore pressure resulting in sediment deformation or failure, such as submarine landslides, sediment slumping, pockmarks and mud volcanoes, soft-sediment deformation and giant hummocks. Moreover, excess pore pressure may be the result of gas hydrate dissociation due to continuous sedimentation, tectonic uplift, sea level fall, heating or inhibitor injection. In order to detect the presence of the overpressure below the BSR, we propose two approachs. The fist approach models the BSR depth versus pore pressure; in fact, if the free gas below the BSR is in overpressure condition, the base of the gas hydrate stability is deeper with respect to the hydrostatic case. This effect causes a discrepancy between seismic and theoretical BSR depths. The second approach models the velocities versus gas hydrate and free gas concentrations and pore pressure, considering the approximation of the Biot theory in case of low frequency, i.e. seismic frequency. Knowing the P and S seismic velocity from seismic data analysis, it is possibile to jointly estimate the gas hydrate and free gas concentrations and the pore pressure regime. Alternatively, if the S-wave velocity is not availbale (due to lack of OBS/OBC data), an AVO analysis can be performed in order to extract information about Poisson ratio. Our modeling suggests that the areas characterized by shallow waters (i.e., areas in which human infrastructures, such as pipelines, are present) are significantly affected by the presence of overpressure condition

  5. The role of fine material and grain size distribution on excess pore pressure dissipation and particle support mechanisms in granular deposits based in large-scale physical experiments

    NASA Astrophysics Data System (ADS)

    Palucis, M. C.; Kaitna, R.; Tewoldebrhan, B.; Hill, K. M.; Dietrich, W. E.

    2011-12-01

    most of the particle's weight, before the pressure slowly declined. When the same boulder was placed on the water-gravel flows, there was no change in fluid pressure, as the mass was supported entirely by grain-grain contacts. These observations suggest that the sustained, but slowly declining elevated pressure in the fines-rich case arises from the boulder forcing fluid displacement, which due to the fluid's high viscosity, only slowly squeezes through the coarse gravel pore space. Hence, the excess fluid pore pressure, in which the fluid fully supports the coarse fractions, observed in experiments and field observations, is not a buoyancy-like effect. Rather, it is the cumulative effect of particles settling against a highly viscous fluid that can sustain and transmit the settling forces through out the flow, as it slowly advects between the particles. These observations are being used to inform models of particle-fluid interactions.

  6. On seismically induced pore pressure and settlement

    USGS Publications Warehouse

    Chen, Albert T.F.

    1988-01-01

    Two different approaches are used to estimate pore pressures and settlement in a 50-ft (15.2-m) sand deposit subjected to a variety of earthquake loadings. Although the two approaches seem consistent in predicting the occurrence of liquefaction, the results show that they are quite divergent in estimating pore-pressure build-ups and magnitude of ground settlement.

  7. Pore pressure embrittlement in a volcanic edifice

    NASA Astrophysics Data System (ADS)

    Farquharson, Jamie; Heap, Michael J.; Baud, Patrick; Reuschlé, Thierry; Varley, Nick R.

    2016-01-01

    The failure mode of porous rock in compression—dilatant or compactant—is largely governed by the overlying lithostatic pressure and the pressure of pore fluids within the rock (Wong, Solid Earth 102:3009-3025, 1997), both of which are subject to change in space and time within a volcanic edifice. While lithostatic pressure will tend to increase monotonously with depth due to the progressive accumulation of erupted products, pore pressures are prone to fluctuations (during periods of volcanic unrest, for example). An increase in pore fluid pressure can result in rock fracture, even at depths where the lithostatic pressure would otherwise preclude such dilatant behaviour—a process termed pore fluid-induced embrittlement. We explore this phenomenon through a series of targeted triaxial experiments on typical edifice-forming andesites (from Volcán de Colima, Mexico). We first show that increasing pore pressure over a range of timescales (on the order of 1 min to 1 day) can culminate in brittle failure of otherwise intact rock. Irrespective of the pore pressure increase rate, we record comparable accelerations in acoustic emission and strain prior to macroscopic failure. We further show that oscillating pore fluid pressures can cause iterative and cumulative damage, ultimately resulting in brittle failure under relatively low effective mean stress conditions. We find that macroscopic failure occurs once a critical threshold of damage is surpassed, suggesting that only small increases in pore pressure may be necessary to trigger failure in previously damaged rocks. Finally, we observe that inelastic compaction of volcanic rock (as we may expect in much of the deep edifice) can be overprinted by shear fractures due to this mechanism of embrittlement. Pore fluid-induced embrittlement of edifice rock during volcanic unrest is anticipated to be highest closer to the conduit and, as a result, may assist in the development of a fractured halo zone surrounding the

  8. Influence of pore pressure and production-induced changes in pore pressure on in situ stress

    SciTech Connect

    Teufel, L.W.

    1996-02-01

    Knowledge of in situ stress and how stress changes with reservoir depletion and pore pressure drawdown is important in a multi-disciplinary approach to reservoir characterization, reservoir management, and improved oil recovery projects. This report summarizes a compilation of in situ stress data from six fields showing the effects of pore pressure and production-induced changes in pore pressure on the minimum horizontal stress. The in situ stress data and corresponding pore pressure data were obtained from field records of the operating companies and published reports. Horizontal stress was determined from closure pressure data of hydraulic fractures and leak-off tests. The stress measurements clearly demonstrate that the total minimum-horizontal stress is dependent on pore pressure. A decrease in pore pressure either by geologic processes or production of a reservoir will result in a decrease in the total minimum-horizontal stress. The magnitude of changes in stress state with net changes in pore pressure is dependent on local field conditions and cannot be accurately predicted by the uniaxial strain model that is commonly used by the petroleum industry.

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

    NASA Astrophysics Data System (ADS)

    Cary, Carlos

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

  10. Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins

    USGS Publications Warehouse

    Major, J.J.; Iverson, R.M.

    1999-01-01

    Measurements of pore-fluid pressure and total bed-normal stress at the base of several ???10 m3 experimental debris flows provide new insight into the process of debris-flow deposition. Pore-fluid pressures nearly sufficient to cause liquefaction were developed and maintained during flow mobilization and acceleration, persisted in debris-flow interiors during flow deceleration and deposition, and dissipated significantly only during postdepositional sediment consolidation. In contrast, leading edges of debris flows exhibited little or no positive pore-fluid pressure. Deposition therefore resulted from grain-contact friction and bed friction concentrated at flow margins. This finding contradicts models that invoke widespread decay of excess pore-fluid pressure, uniform viscoplastic yield strength, or pervasive grain-collision stresses to explain debris-flow deposition. Furthermore, the finding demonstrates that deposit thickness cannot be used to infer the strength of flowing debris.

  11. Effect of pore pressure on damage accumulation in salt

    SciTech Connect

    PFEIFLE,T.W.; HURTADO,L. DIANE

    2000-06-12

    Laboratory data acquired from two multistage, triaxial compression creep experiments are presented for bedded salt. The experiments were conducted to study the effect of pore pressure changes on the accumulation of damage (dilatant volumetric strain). The first experiment comprised five constant total stress tests in which the internal pore pressure was incremented during successive stages, while the externally applied axial and radial stresses were maintained constant. The second experiment comprised three constant effective stress tests in which the pore pressure and the externally applied axial and radial stresses were increased in equal increments in successive stages. Volumetric strain rates were determined both before and after the pore pressure changes were made in all tests. The data suggest pore pressure changes made during the constant total stress tests have a greater effect on salt dilation than do changes made during the constant effective stress tests.

  12. Pore-water pressures associated with clogging of soil pipes: Numerical analysis of laboratory experiments

    USDA-ARS?s Scientific Manuscript database

    Clogging of soil pipes due to excessive internal erosion has been hypothesized to cause extreme erosion events such as landslides, debris flows, and gullies, but confirmation of this phenomenon has been lacking. Laboratory and field measurements have failed to measure pore water pressures within pip...

  13. Compaction and Permeability Reduction of Castlegate Sandstone under Pore Pressure Cycling

    NASA Astrophysics Data System (ADS)

    Bauer, S. J.

    2014-12-01

    We investigate time-dependent compaction and permeability changes by cycling pore pressure with application to compressed air energy storage (CAES) in a reservoir. Preliminary experiments capture the impacts of hydrostatic stress, pore water pressure, pore pressure cycling, chemical, and time-dependent considerations near a borehole in a CAES reservoir analog. CAES involves creating an air bubble in a reservoir. The high pressure bubble serves as a mechanical battery to store potential energy. When there is excess grid energy, bubble pressure is increased by air compression, and when there is energy needed on the grid, stored air pressure is released through turbines to generate electricity. The analog conditions considered are depth ~1 km, overburden stress ~20 MPa and a pore pressure ~10MPa. Pore pressure is cycled daily or more frequently between ~10 MPa and 6 MPa, consistent with operations of a CAES facility at this depth and may continue for operational lifetime (25 years). The rock can vary from initially fully-to-partially saturated. Pore pressure cycling changes the effective stress.Jacketed, room temperature tap water-saturated samples of Castlegate Sandstone are hydrostatically confined (20 MPa) and subjected to a pore pressure resulting in an effective pressure of ~10 MPa. Pore pressure is cycled between 6 to 10 MPa. Sample displacement measurements yielded determinations of volumetric strain and from water flow measurements permeability was determined. Experiments ran for two to four weeks, with 2 to 3 pore pressure cycles per day. The Castlegate is a fluvial high porosity (>20%) primarily quartz sandstone, loosely calcite cemented, containing a small amount of clay.Pore pressure cycling induces compaction (~.1%) and permeability decreases (~20%). The results imply that time-dependent compactive processes are operative. The load path, of increasing and decreasing pore pressure, may facilitate local loosening and grain readjustments that results in the

  14. Connecting Wastewater Injection and Seismicity through Pore Pressure

    NASA Astrophysics Data System (ADS)

    Ge, S.; Weingarten, M.; Person, M. A.; Bekins, B. A.

    2014-12-01

    Increased seismicity in recent years in some geologically quiescent regions in the US has been linked to wastewater injection associated with oil and gas production. While seismicity in some cases appears to be well correlated with injection activities, in many other injection locations no seismicity has been reported. How pore pressures generated from injection propagate spatially and evolve temporally is likely a key control in inducing earthquakes, providing a physical linkage between injection activity and seismicity occurrence. Yet, the linkage remains controversial and inconclusive, in spite of the basic physics of pore pressure propagation being well established. This study aims at better understanding the physical processes of pore pressure propagation around injection sites and identifying factors that are most likely contributors to induced seismicity. Numerical modeling suggests that pore pressure increases in the Jones seismicity swarm northeast of Oklahoma City were primarily from several high rate injection wells. Preliminary analysis on injection and seismicity data from Greeley, Colorado also points to a potential pore pressure link between high injection rates and seismicity. Modeling of pore pressures in the Lake County, Ohio, illustrates that permeable faults in the crystalline basement could facilitate pore pressure propagation from injection in the basal aquifer and host earthquakes, which could explain the earthquakes that occurred in the mid-1980s. In many of the above examples, wastewater injection in basal aquifers promoted downward propagation of pore pressures into the crystalline basement. In connecting injection and seismicity through pore pressure propagation, high rate injection wells and permeable basement faults are merging as important players contributing to induced seismicity. It is the intention of this study that findings like these would provide a scientific basis to inform future regulations and policies on wastewater

  15. Upscaling pore pressure-dependent gas permeability in shales

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Javadpour, Farzam

    2017-04-01

    Upscaling pore pressure dependence of shale gas permeability is of great importance and interest in the investigation of gas production in unconventional reservoirs. In this study, we apply the Effective Medium Approximation, an upscaling technique from statistical physics, and modify the Doyen model for unconventional rocks. We develop an upscaling model to estimate the pore pressure-dependent gas permeability from pore throat size distribution, pore connectivity, tortuosity, porosity, and gas characteristics. We compare our adapted model with six data sets: three experiments, one pore-network model, and two lattice-Boltzmann simulations. Results showed that the proposed model estimated the gas permeability within a factor of 3 of the measurements/simulations in all data sets except the Eagle Ford experiment for which we discuss plausible sources of discrepancies.

  16. Regulation of landslide motion by dilatancy and pore pressure feedback

    USGS Publications Warehouse

    Iverson, R.M.

    2005-01-01

    A new mathematical model clarifies how diverse styles and rates of landslide motion can result from regulation of Coulomb friction by dilation or contraction of water-saturated basal shear zones. Normalization of the model equations shows that feedback due to coupling between landslide motion, shear zone volume change, and pore pressure change depends on a single dimensionless parameter ??, which, in turn, depends on the dilatancy angle ?? and the intrinsic timescales for pore pressure generation and dissipation. If shear zone soil contracts during slope failure, then ?? 0, and negative feedback permits slow, steady landslide motion to occur while positive pore pressure is supplied by rain infiltration. Steady state slip velocities v0 obey v0 = -(K/??) p*e, where K is the hydraulic conductivity and p*e is the normalized (dimensionless) negative pore pressure generated by dilation. If rain infiltration and attendant pore pressure growth continue unabated, however, their influence ultimately overwhelms the stabilizing influence of negative p*e. Then, unbounded landslide acceleration occurs, accentuated by an instability that develops if ?? diminishes as landslide motion proceeds. Nonetheless, numerical solutions of the model equations show that slow, nearly steady motion of a clay-rich landslide may persist for many months as a result of negative pore pressure feedback that regulates basal Coulomb friction. Similarly stabilized motion is less likely to occur in sand-rich landslides that are characterized by weaker negative feedback.

  17. Quantification of subsurface pore pressure through IODP drilling

    NASA Astrophysics Data System (ADS)

    Saffer, D. M.; Flemings, P. B.

    2010-12-01

    It is critical to understand the magnitude and distribution of subsurface pore fluid pressure: it controls effective stress and thus mechanical strength, slope stability, and sediment compaction. Elevated pore pressures also drive fluid flows that serve as agents of mass, solute, and heat fluxes. The Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) have provided important avenues to quantify pore pressure in a range of geologic and tectonic settings. These approaches include 1) analysis of continuous downhole logs and shipboard physical properties data to infer compaction state and in situ pressure and stress, 2) laboratory consolidation testing of core samples collected by drilling, 3) direct downhole measurements using pore pressure probes, 3) pore pressure and stress measurements using downhole tools that can be deployed in wide diameter pipe recently acquired for riser drilling, and 4) long-term monitoring of formation pore pressure in sealed boreholes within hydraulically isolated intervals. Here, we summarize key advances in quantification of subsurface pore pressure rooted in scientific drilling, highlighting with examples from subduction zones, the Gulf of Mexico, and the New Jersey continental shelf. At the Nankai, Costa Rican, and Barbados subduction zones, consolidation testing of cores samples, combined with analysis of physical properties data, indicates that even within a few km landward of the trench, pore pressures in and below plate boundary décollement zones reach a significant fraction of the lithostatic load (λ*=0.25-0.91). These results document a viable and quantifiable mechanism to explain the mechanical weakness of subduction décollements, and are corroborated by a small number of direct measurements in sealed boreholes and by inferences from seismic reflection data. Recent downhole measurements conducted during riser drilling using the modular formation dynamics tester wireline tool (MDT) in a forearc basin ~50

  18. Study of pore pressure reaction on hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Trimonova, Mariia; Baryshnikov, Nikolay; Turuntaev, Sergey; Zenchenko, Evgeniy; Zenchenko, Petr

    2017-04-01

    We represent the results of the experimental study of the hydraulic fracture propagation influence on the fluid pore pressure. Initial pore pressure was induced by injection and production wells. The experiments were carried out according to scaling analysis based on the radial model of the fracture. All required geomechanical and hydrodynamical properties of a sample were derived from the scaling laws. So, gypsum was chosen as a sample material and vacuum oil as a fracturing fluid. The laboratory setup allows us to investigate the samples of cylindrical shape. It can be considered as an advantage in comparison with standard cubic samples, because we shouldn't consider the stress field inhomogeneity induced by the corners. Moreover, we can set 3D-loading by this setting. Also the sample diameter is big enough (43cm) for placing several wells: the fracturing well in the center and injection and production wells on two opposite sides of the central well. The experiment consisted of several stages: a) applying the horizontal pressure; b) applying the vertical pressure; c) water solution injection in the injection well with a constant pressure; d) the steady state obtaining; e) the oil injection in the central well with a constant rate. The pore pressure was recorded in the 15 points along bottom side of the sample during the whole experiment. We observe the pore pressure change during all the time of the experiment. First, the pore pressure changed due to water injection. Then we began to inject oil in the central well. We compared the obtained experimental data on the pore pressure changes with the solution of the 2D single-phase equation of pore-elasticity, and we found significant difference. The variation of the equation parameters couldn't help to resolve the discrepancy. After the experiment, we found that oil penetrated into the sample before and after the fracture initiation. This fact encouraged us to consider another physical process - the oil

  19. Pore fluid pressure, apparent friction, and Coulomb failure

    USGS Publications Warehouse

    Beeler, N.M.; Simpson, R.W.; Hickman, S.H.; Lockner, D.A.

    2000-01-01

    Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of both friction and pore pressure, but is a material constant only if changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the potential failure plane. Although specific models of fault zones permit such a relation, neither is it known that fault zones within the Earth behave this way, nor is this behavior expected in all cases. In contrast, for an isotropic homogeneous poroelastic model the pore pressure changes are proportional to changes in mean stress, μ′ is not a material constant, and −∞ ≤ μ′ ≤ +∞. Analysis of the change in Coulomb failure stress for tectonically loaded reverse and strike-slip faults shows considerable differences between these two pore pressure models, suggesting that such models might be distinguished from one another using observations of triggered seismicity (e.g., aftershocks). We conclude that using the constant apparent friction model exclusively in studies of Coulomb failure stress is unwise and could lead to significant errors in estimated stress change and seismic hazard.

  20. Pore fluid pressure in impermeable fault zones throughout earthquake cycles

    NASA Astrophysics Data System (ADS)

    Goswami, A. S.; Barbot, S.; Moore, J. D. P.; Lambert, V.

    2016-12-01

    Earthquakes affect the pore pressure in the crust, leading to dynamic changes in the water table and deformation of the surrounding rocks. Variations in pore pressure can have a strong effect on fault strength and modulate the earthquake cycle, potentially affecting the recurrence and the magnitude of seismicity. Poroelastic rebound has been observed following large and moderate earthquakes but its effect has been challenging to incorporate in time-dependent dynamic models of earthquake cycles, or even in dynamic models of postseismic relaxation. Here, we present a new methodology to incorporate the pore fluid diffusion and poroelastic effects in quasi-dynamic models of slip evolution. We study the case of a dipping thrust fault surrounded by an impermeable fault zone in plane strain condition. The solution method employs newly derived analytic solutions for the stress interactions caused by isotropic strain in finite volume of deformation. We use the integral method to solve the coupled governing equations of poroelasticity and fault slip evolution. We consider the full coupling of fault strength with pore pressure and solve for the evolution of the water table throughout multiple earthquake cycles. We then present simulations of postseismic rebound in the case of three-dimensional deformation following thrust and strike-slip earthquakes on finite faults. Our formulation opens the door to assimilating time-dependent deformation and pore pressure data to constrain the physical properties of crustal rocks. Our approach constitutes an important step towards a unified representation of all the important mechanisms of deformation throughout the earthquake cycle.

  1. Pore fluid pressure and shear behavior in debris flows of different compositions

    NASA Astrophysics Data System (ADS)

    Kaitna, Roland; Palucis, Marisa; Yohannes, Bereket; Hill, Kimberly; Dietrich, William

    2016-04-01

    Debris flows are mixtures of sediment and water that can have a wide range of different grain size distributions and water contents. The composition of the material is expected to have a strong effect on the development of pore fluid pressures in excess to hydrostatic, which in turn might affect the internal deformation behavior. We present a set of large scale experiments with debris flow mixtures of different compositions in a 4-m diameter rotating drum. Longitudinal profiles of basal fluid pressure and normal stress were measured and a probe to determine fluid pressure at different depths within the flow was developed and tested. Additionally we determined vertical profiles of mean particle velocities in the flow interior by measuring small variations of conductivity of the passing material and calculating the time lag between signals from two independent measurements at a small, known distance apart. Mean values of basal pore fluid pressure range from hydrostatic pressure for gravel-water flows to nearly complete liquefaction for muddy mixtures having a wide grain size distribution. The data indicate that the presence of fines dampens fluctuations of normalized fluid pressure and normal stress and concentrates shear at the base. The mobility of grain-fluid flows is strongly enhanced by a combination of fines in suspension as part of the interstitial fluid and a wide grain size distribution. Excess fluid pressure may arise from fluid displacement by converging grains at the front of the flow and the slow settling of grains through a highly viscous non-Newtonian fluid. Our findings support the need for pore pressure evolution and diffusion equations in debris flow models as they depend on particle size distributions. This study contributes to the understanding of the production of excess fluid pressure in grain fluid mixtures and may guide the development of constitutive models that describe natural events.

  2. Variability of in situ sediment strength and pore pressure behavior of tidal estuary surface sediments

    NASA Astrophysics Data System (ADS)

    Lucking, Greg; Stark, Nina; Lippmann, Thomas; Smyth, Stephen

    2017-10-01

    Tidal estuaries feature spatially and temporally varying sediment dynamics and characteristics. Particularly, the variability of geotechnical sediment parameters is still poorly understood, limiting the prediction of long-term sediment stability and dynamics. This paper presents results from an in situ investigation of surficial sediments (≤50 cm) in a tidal estuary in New Hampshire (USA), using a portable free fall penetrometer. The aim is to investigate variations in sediment strength and pore pressure behavior with regard to sediment type and seabed morphology. The study also provides a detailed analysis of high velocity impact pore pressure data to derive information about sediment type and permeability. The penetrometer was deployed 227 times, and the findings are correlated to 78 sediment samples. Differences in sediment strength and type were found when transitioning from tidal flats to the deeper channels. Finer-grained sediments located predominantly on the tidal flats appeared well consolidated with noticeable and spatially consistent sediment strength (reflected in an estimate of quasi-static bearing capacity qsbcmax 10 kPa). Sediments with higher sand content (>75%) showed more variations in strength relating to differences in gradation, and likely represent loose and poorly consolidated sands (qsbcmax 10-55 kPa). The rate at which the recorded excess pore pressures approached equilibrium after penetration was classified and related to sediment type. The data indicate that the development of excess pore pressures upon impact and during penetration may provide additional insight into the nature and layering of bed material, such as identifying a desiccated or over-consolidated dilative surficial layer. In summary, with varying sediment grain size distributions, bulk densities and morphology, sediment strength and pore pressure behavior can vary significantly within a tidal estuary.

  3. Variability of in situ sediment strength and pore pressure behavior of tidal estuary surface sediments

    NASA Astrophysics Data System (ADS)

    Lucking, Greg; Stark, Nina; Lippmann, Thomas; Smyth, Stephen

    2017-01-01

    Tidal estuaries feature spatially and temporally varying sediment dynamics and characteristics. Particularly, the variability of geotechnical sediment parameters is still poorly understood, limiting the prediction of long-term sediment stability and dynamics. This paper presents results from an in situ investigation of surficial sediments (≤50 cm) in a tidal estuary in New Hampshire (USA), using a portable free fall penetrometer. The aim is to investigate variations in sediment strength and pore pressure behavior with regard to sediment type and seabed morphology. The study also provides a detailed analysis of high velocity impact pore pressure data to derive information about sediment type and permeability. The penetrometer was deployed 227 times, and the findings are correlated to 78 sediment samples. Differences in sediment strength and type were found when transitioning from tidal flats to the deeper channels. Finer-grained sediments located predominantly on the tidal flats appeared well consolidated with noticeable and spatially consistent sediment strength (reflected in an estimate of quasi-static bearing capacity qsbcmax 10 kPa). Sediments with higher sand content (>75%) showed more variations in strength relating to differences in gradation, and likely represent loose and poorly consolidated sands (qsbcmax 10-55 kPa). The rate at which the recorded excess pore pressures approached equilibrium after penetration was classified and related to sediment type. The data indicate that the development of excess pore pressures upon impact and during penetration may provide additional insight into the nature and layering of bed material, such as identifying a desiccated or over-consolidated dilative surficial layer. In summary, with varying sediment grain size distributions, bulk densities and morphology, sediment strength and pore pressure behavior can vary significantly within a tidal estuary.

  4. A laboratory study of particle ploughing and pore-pressure feedback: A velocity-weakening mechanism for soft glacier beds

    USGS Publications Warehouse

    Thomason, J.F.; Iverson, N.R.

    2008-01-01

    If basal-water discharge and pressure are sufficiently high, a soft-bedded glacier will slip over its bed by ploughing, the process in which particles that span the ice-bed interface are dragged across the bed surface. Results of laboratory experiments indicate that resistance to ploughing can decrease with increasing ploughing velocity (velocity weakening). During ploughing at various velocities (15-400 ma-1), till was compacted in front of idealized particles, causing pore pressures there that were orders of magnitude higher than the ambient value. This excess pore pressure locally weakened the till in shear, thereby decreasing ploughing resistance by a factor of 3.0-6.6 with a six-fold increase in ploughing velocity. Characteristic timescales of pore-pressure diffusion and compaction down-glacier from ploughing particles depend on till diffusivity, ploughing velocity and sizes of ploughing particles. These timescales accurately predict the ranges of these variables over which excess pore pressure and velocity weakening occurred. Existing ploughing models do not account for velocity weakening. A new ploughing model with no adjustable parameters predicts ploughing resistance to no worse than 38% but requires that excess pore pressures be measured. Velocity weakening by this mechanism may affect fast glacier flow, sediment transport by bed deformation and basal seismicity.

  5. One-dimensional pore pressure diffusion of different grain-fluid mixtures

    NASA Astrophysics Data System (ADS)

    von der Thannen, Magdalena; Kaitna, Roland

    2015-04-01

    During the release and the flow of fully saturated debris, non-hydrostatic fluid pressure can build up and probably dissipate during the event. This excess fluid pressure has a strong influence on the flow and deposition behaviour of debris flows. Therefore, we investigate the influence of mixture composition on the dissipation of non-hydrostatic fluid pressures. For this we use a cylindrical pipe of acrylic glass with installed pore water pressure sensors in different heights and measure the evolution of the pore water pressure over time. Several mixtures with variable content of fine sediment (silt and clay) and variable content of coarse sediment (with fixed relative fractions of grains between 2 and 32 mm) are tested. For the fines two types of clay (smectite and kaolinite) and loam (Stoober Lehm) are used. The analysis is based on the one-dimensional consolidation theory which uses a diffusion coefficient D to model the decay of excess fluid pressure over time. Starting from artificially induced super-hydrostatic fluid pressures, we find dissipation coefficients ranging from 10-5 m²/s for liquid mixtures to 10-8 m²/s for viscous mixtures. The results for kaolinite and smectite are quite similar. For our limited number of mixtures the effect of fines content is more pronounced than the effect of different amounts of coarse particles.

  6. Measuring Fluid Pressure on the Pore-scale

    NASA Astrophysics Data System (ADS)

    Giordano, N.; Petrovitch, C.; Pyrak-Nolte, L. J.

    2008-12-01

    The capillary pressure plays an important role in theoretical descriptions of immiscible two-phase flow in porous media. Most measurements of capillary pressure on the pore-scale are either based on external measurements of the fluid pressure of two immiscible fluids in a porous media or extracted from the analysis of interfacial curvature from digital-photomicroscopy. Experimentally, it is very difficult to measure local pressure at the interface of a two-phase flow system at the pore scale. In this study, we developed micro- capacitors for measuring local pressures in two-dimensional micro-models. Micro-models are transparent microfluidic flow cells that enable direct imaging of fluid distributions in known pore geometries. They are made using photo-projection lithography to make percolative structures that have areal dimensions of 600 µm x 600 µm with an aperture of 2.0 μ m. The size of the micro-model enables full-frame optical imaging during drainage and imbibition experiments. We have modified the micro-model fabrication process to include micro-capacitors to measure local pressure. We added two thin metal films to the opposing glass substrates prior to our normal micromodel assembly. The metal films act as a parallel plate capacitor. The capacitance depends on the dielectric material inside the plates which in our study is decane and nitrogen. As the pressure in the fluids changes, there is a corresponding change in the density of the fluid, and hence a change in the dielectric constant. The changes in dieletric constant are measured via precision measurements of the capacitance. Capacitance changes as small of 1/107 are measured which corresponds to pressure changes of 102 Pa. This pressure resolution is approximately 1% of the full range in our typical drainage/imbibition cycles. This capacitance method enables us to make measurements of small pressure changes with high spatial resolution. The spatial resolution is set by the size of the capacitor

  7. Using Advanced Tensiometers to Monitor Temporal Variations in Pore Pressure

    NASA Astrophysics Data System (ADS)

    Nichols, R. L.; Young, M. H.; Dixon, K. L.; Rossabi, J.; Hyde, W. K.; Holmes-Burns, H.

    2002-12-01

    The Savannah River Site has installed a comprehensive vadose zone monitoring system (VZMS) at it's low level radioactive waste disposal facility to collect the necessary information to calculate contaminant flux. The VZMS includes water content reflectometers, suction lysimeters, advanced tensiometers (ATs), water flux meters, access ports for neutron probes, and a tipping bucket rain gauge. Forty one ATs were installed from 1999 to 2001 at depths ranging from 2 to 60 feet and have been operated continuously. The installation depths were based on a hydrostatigraphic model developed from core logs, cone penetrometer logs, moisture content profiles, water retention curves model that were obtained during the phased installation of the VZMS. An AT consists of a porous cup installed at a prescribed depth with casing back to the surface and a pressure transducer that is lowered into the casing and connects with the porous cup. The pressure transducer transmits it's signal to a datalogger where the data is stored for future retrieval using a cellular phone communications package. Results from the 2 year operating period show that the AT calibrations are stable and t ATs are capable of extended monitoring of pore pressures in the 0 to 300 cm H2 O range. The ATs had sufficient resolution to detect the naturally occurring fluctuations in pore pressure (1 to 100 cm H2 O over 1 to 72 hours) that resulted from infiltration events at the site. The stable performance of the ATs combined with their ability to detect naturally occurring fluctuations in pore pressure make the ATs a useful tool in measuring temporal pore pressure variations for use in calibrating numerical models of fluid flow in variably saturated porous media.

  8. Pore pressure estimation from velocity data: Accounting for overpressure mechanisms besides undercompaction

    SciTech Connect

    Bowers, G.L.

    1995-06-01

    A new method for estimating pore pressure from formation sonic velocity data is presented. Unlike previous techniques, this method accounts for excess pressure generated by both undercompaction, and fluid expansion mechanisms such as aquathermal pressuring, hydrocarbon maturation, clay diagenesis, and charging from other zones. The method is an effective stress approach; the effective stress is computed from the velocity, and the result is subtracted from the overburden stress to obtain pore pressure. to include multiple sources of overpressure, a pair of velocity-vs.-effective-stress relations are introduced. One relation accounts for normal pressure and overpressure caused by undercompaction. The second is applied inside velocity reversal zones caused by fluid expansion mechanisms. Example applications of the method are presented from the U.S. gulf coast, the Gulf of Mexico, and the Central North Sea. some other pore pressure estimation approaches are also examined to demonstrate how these techniques have unknowingly accounted for overpressure mechanisms other than undercompaction. It is also explained how velocity-vs.-effective-stress data can be used to identify the general cause of overpressure in an area. For instance, the empirical correlation of Hottman and Johnson indicates that overpressure along the US gulf coast cannot be due only to undercompaction.

  9. Effects of confining pressure, pore pressure and temperature on absolute permeability. SUPRI TR-27

    SciTech Connect

    Gobran, B.D.; Ramey, H.J. Jr.; Brigham, W.E.

    1981-10-01

    This study investigates absolute permeability of consolidated sandstone and unconsolidated sand cores to distilled water as a function of the confining pressure on the core, the pore pressure of the flowing fluid and the temperature of the system. Since permeability measurements are usually made in the laboratory under conditions very different from those in the reservoir, it is important to know the effect of various parameters on the measured value of permeability. All studies on the effect of confining pressure on absolute permeability have found that when the confining pressure is increased, the permeability is reduced. The studies on the effect of temperature have shown much less consistency. This work contradicts the past Stanford studies by finding no effect of temperature on the absolute permeability of unconsolidated sand or sandstones to distilled water. The probable causes of the past errors are discussed. It has been found that inaccurate measurement of temperature at ambient conditions and non-equilibrium of temperature in the core can lead to a fictitious permeability reduction with temperature increase. The results of this study on the effect of confining pressure and pore pressure support the theory that as confining pressure is increased or pore pressure decreased, the permeability is reduced. The effects of confining pressure and pore pressure changes on absolute permeability are given explicitly so that measurements made under one set of confining pressure/pore pressure conditions in the laboratory can be extrapolated to conditions more representative of the reservoir.

  10. High-pressure alchemy on a small-pore zeolite

    NASA Astrophysics Data System (ADS)

    Lee, Y.

    2011-12-01

    While an ever-expanding variety of zeolites with a wide range of framework topology is available, it is desirable to have a way to tailor the chemistry of the zeolitic nanopores for a given framework topology via controlling both the coordination-inclusion chemistry and framework distortion/relaxation. This is, however, subjected to the ability of a zeolitic nanopore to allow the redistribution of cations-water assembly and/or insertion of foreign molecules into the pores and channels. Small-pore zeolites such as natrolite (Na16Al16Si24O80x16H2O), however, have been known to show very limited capacity for any changes in the confinement chemistry. We have recently shown that various cation-exchanged natrolites can be prepared under modest conditions from natural sodium natrolite and exhibit cation-dependent volume expansions by up to 18.5% via converting the elliptical channels into progressively circular ones. Here, we show that pressure can be used as a unique and clean tool to further manipulate the chemistry of the natrolite nanopores. Our recent crystallographic and spectroscopic studies of pressure-insertion of foreign molecules, trivalent-cation exchange under pressure, and pressure-induced inversion of cation-water coordination and pore geometry in various cation-exchanged natrolites will be presented.

  11. Pore Pressure Distribution and Flank Instability in Hydrothermally Altered Stratovolcanoes

    NASA Astrophysics Data System (ADS)

    Ball, J. L.; Taron, J.; Hurwitz, S.; Reid, M. E.

    2015-12-01

    Field and geophysical investigations of stratovolcanoes with long-lived hydrothermal systems commonly reveal that initially permeable regions (such as brecciated layers of pyroclastic material) can become both altered and water-bearing. Hydrothermal alteration in these regions, including clay formation, can turn them into low-permeability barriers to fluid flow, which could increase pore fluid pressures resulting in flank slope instability. We examined elevated pore pressure conditions using numerical models of hydrothermal flow in stratovolcanoes, informed by geophysical data about internal structures and deposits. Idealized radially symmetric meshes were developed based on cross-sectional profiles and alteration/permeability structures of Cascade Range stratovolcanoes. We used the OpenGeoSys model to simulate variably saturated conditions in volcanoes heated only by regional heat fluxes, as well as 650°C intrusions at two km depth below the surface. Meteoric recharge was estimated from precipitation rates in the Cascade Range. Preliminary results indicate zones of elevated pore pressures form: 1) where slopes are underlain by continuous low-permeability altered layers, or 2) when the edifice has an altered core with saturated, less permeable limbs. The first scenario might control shallow collapses on the slopes above the altered layers. The second could promote deeper flank collapses that are initially limited to the summit and upper slopes, but could progress to the core of an edifice. In both scenarios, pore pressures can be further elevated by shallow intrusions, or evolve over longer time scales under forcing from regional heat flux. Geometries without confining low-permeability layers do not show these pressure effects. Our initial scenarios use radially symmetric models, but we are also simulating hydrothermal flow under real 3D geometries with asymmetric subsurface structures (Mount Adams). Simulation results will be used to inform 3D slope

  12. Constraints on Pore Pressure in Subduction Zones From Geotechnical Tests and Physical Properties Data

    NASA Astrophysics Data System (ADS)

    Saffer, D. M.; McKiernan, A. W.

    2005-12-01

    At subduction zones, as incoming sediments are either offscraped or underthrust at the trench, elevated pore pressures result from the combination of rapid loading and low permeability. Pore pressure within underthrust sediment is especially important for the mechanical strength of the plate boundary fault system, because the main décollement localizes immediately above this sediment, and at many subduction zones steps downward into it. Because the underthrust sediment undergoes progressive uniaxial (vertical) strain, quantitative estimates of in situ pore pressure can be obtained by several methods, including: (1) maximum past burial stress ( Pv'}) from laboratory consolidation tests on core samples, and (2) observed compaction trends in boreholes. These methods allow a detailed view of pore pressure and its variability down-section, providing insight into dewatering processes and the evolution of shear strength relevant to early development of the décollement. Geotechnical tests also provide independent measurement of the coefficient of consolidation ( Cv), compressibility ( mv), and permeability (k) of sediment samples, which can be used to parameterize forward models of pressure generation. Here, I discuss pore pressure estimates derived from (1) consolidation tests on core samples, and (2) observed porosity profiles, along transects where ODP drilling has sampled sediment at the Nankai, N. Barbados, and Costa Rican subduction zones. At all three margins, the two independent methods yield consistent results, and indicate development of significant overpressures that increase systematically with distance from the trench. The values are in good agreement with direct measurements in 2 instrumented boreholes at Barbados, maximum and minimum bounds from the known loading rate, and results of 2-D numerical models of fluid flow. Inferred pressures document nearly undrained conditions at the base of the section (excess pressures equal to the load emplaced by

  13. Influence of pore pressure change on coseismic volumetric strain

    NASA Astrophysics Data System (ADS)

    Wang, Chi-Yuen; Barbour, Andrew J.

    2017-10-01

    Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

  14. Postseismic Pore Pressure Diffusion and its Relationship to Aftershock Sequences

    NASA Astrophysics Data System (ADS)

    Lindman, M.; Lund, B.; Roberts, R.

    2006-12-01

    InSAR measurements of postseismic deformation, water level changes in geothermal wells and time dependent tomography after the two June 2000 M6.5 earthquakes in the south Iceland seismic zone (SISZ) have revealed poroelastic rebound and fluid flow to take place in the postseismic period. This and other examples of pore pressure induced seismicity indicate a strong coupling between fluid flow and the occurrence of earthquakes. It has been suggested that the diffusion of pore pressures induced by a main shock is directly related to the temporal behaviour of aftershocks, described by the well established Omori law. The Omori law describes the rate of aftershocks to decay with time t after a main shock as {dn/dt}={K/(c+t)^p}. The parameter c, reflecting a roughly constant rate during the initial c seconds, is controversial as it is debated whether this behaviour reflects incomplete detection of earthquakes, or, a true description of the physics of the aftershock process. Physical models of aftershock occurrence, including pore pressure diffusion, do suggest that this initial behaviour can indeed be related to the physics of the process. Aftershock sequences within the SISZ indicate that c increases with the magnitude of the main shock. To investigate whether this can be reconciled with postseismic pore pressure diffusion we have modelled the diffusion process following earthquakes of two different magnitudes, M_w=4.6 and M_w=2.2, respectively. We show that the sequences of induced seismicity by these diffusion processes do obey the Omori law, with a magnitude dependency of c that is consistent with the data. We also note that our model captures general features of the spatial variation with time in the aftershock sequences from SISZ that we have studied. An interesting observation in real aftershock sequences is the occurrence of secondary aftershock clusters that results in a temporary rate increase. Our modelling indicates that this feature may be explained by

  15. Reservoir transport and poroelastic properties from oscillating pore pressure experiments

    NASA Astrophysics Data System (ADS)

    Hasanov, Azar K.

    Hydraulic transport properties of reservoir rocks, permeability and storage capacity are traditionally defined as rock properties, responsible for the passage of fluids through the porous rock sample, as well as their storage. The evaluation of both is an important part of any reservoir characterization workflow. Moreover, permeability and storage capacity are main inputs into any reservoir simulation study, routinely performed by reservoir engineers on almost any major oil and gas field in the world. An accurate reservoir simulation is essential for production forecast and economic analysis, hence the transport properties directly control the profitability of the petroleum reservoir and their estimation is vital for oil and gas industry. This thesis is devoted to an integrated study of reservoir rocks' hydraulic, streaming potential and poroelastic properties as measured with the oscillating pore pressure experiment. The oscillating pore pressure method is traditionally used to measure hydraulic transport properties. We modified the method and built an experimental setup, capable of measuring all aforementioned rock properties simultaneously. The measurements were carried out for four conventional reservoir-rock quality samples at a range of oscillation frequencies and effective stresses. An apparent frequency dependence of permeability and streaming potential coupling coefficient was observed. Measured frequency dispersion of drained poroelastic properties indicates an intrinsically inelastic nature of the porous mineral rock frame. Standard Linear Model demonstrated the best fit to the experimental dispersion data. Pore collapse and grain crushing effects took place during hydrostatic loading of the dolomitic sample and were observed in permeability, coupling coefficient and poroelastic measurements simultaneously. I established that hydraulically-measured storage capacities are overestimated by almost one order of magnitude when compared to elastically

  16. Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

    NASA Astrophysics Data System (ADS)

    Mukuhira, Yusuke; Moriya, Hirokazu; Ito, Takatoshi; Asanuma, Hiroshi; Häring, Markus

    2017-04-01

    Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous-induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates farther and faster and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.

  17. Pressure-induced gelatinization of starch in excess water.

    PubMed

    Vallons, Katleen J R; Ryan, Liam A M; Arendt, Elke K

    2014-01-01

    High pressure processing is a promising non-thermal technology for the development of fresh-like, shelf-stable foods. The effect of high pressure on starch has been explored by many researchers using a wide range of techniques. In general, heat and pressure have similar effects: if sufficiently high, they both induce gelatinization of starch in excess water, resulting in a transition of the native granular structure to a starch paste or gel. However, there are significant differences in the structural and rheological properties between heated and pressurized starches. These differences offer benefits with respect to new product development. However, in order to implement high-pressure technology to starch and starch-containing products, a good understanding of the mechanism of pressure-induced gelatinization is necessary. Studies that are published in this area are reviewed, and the similarities and differences between starches gelatinized by pressure and by temperature are summarized.

  18. Explicit Pore Pressure Material Model in Carbon-Cloth Phenolic

    NASA Technical Reports Server (NTRS)

    Gutierrez-Lemini, Danton; Ehle, Curt

    2003-01-01

    An explicit material model that uses predicted pressure in the pores of a carbon-cloth phenolic (CCP) composite has been developed. This model is intended to be used within a finite-element model to predict phenomena specific to CCP components of solid-fuel-rocket nozzles subjected to high operating temperatures and to mechanical stresses that can be great enough to cause structural failures. Phenomena that can be predicted with the help of this model include failures of specimens in restrained-thermal-growth (RTG) tests, pocketing erosion, and ply lifting

  19. Surge dynamics coupled to pore-pressure evolution in debris flows

    USGS Publications Warehouse

    Savage, S.B.; Iverson, R.M.; ,

    2003-01-01

    Temporally and spatially varying pore-fluid pressures exert strong controls on debris-flow motion by mediating internal and basal friction at grain contacts. We analyze these effects by deriving a one-dimensional model of pore-pressure diffusion explicitly coupled to changes in debris-flow thickness. The new pore-pressure equation is combined with Iverson's (1997) extension of the depth-averaged Savage-Hutter (1989, 1991) granular avalanche equations to predict motion of unsteady debris-flow surges with evolving pore-pressure distributions. Computational results illustrate the profound effects of pore-pressure diffusivities on debris-flow surge depths and velocities. ?? 2003 Millpress,.

  20. The ability of rock physics models to infer marine in situ pore pressure

    NASA Astrophysics Data System (ADS)

    Hornbach, Matthew J.; Manga, Michael

    2014-12-01

    fluid pressure is an important parameter defining the mechanical strength of marine sediments. Obtaining high spatial resolution in situ pore pressure measurements in marine sediments, however, is a challenge, and as a result, only a handful of in situ pore pressure measurements exist at scientific drill sites. Integrating rock physics models with standard IODP/ODP measurements provides a potentially widely applicable approach for calculating in situ pore pressure. Here we use a rock physics approach to estimate in situ pore pressure at two Scientific Ocean Drill Sites where in situ pressure is well constrained: ODP Site 1173, used as reference for normal (hydrostatic) fluid pressures, and ODP Site 948, where previous studies infer high fluid pressures (λ* ˜ 0.45-0.95, where the pore pressure ratio λ* is defined as the pore pressure above hydrostatic divided by the difference between the largest principal stress and hydrostatic stress). Our analysis indicates that the rock physics method provides an accurate, low-precision method for estimating in situ pore pressure at these drill sites, and sensitivity analysis indicates this method can detect modestly high (λ* > 0.6) pore pressure at the 95% confidence level. This approach has broad applicability because it provides an inexpensive, high-resolution (meter-scale) method for retrospectively detecting and quantifying high pore pressure at any drill site where quality wireline logs and ocean drilling data exist.

  1. Excess cholesterol inhibits glucose-stimulated fusion pore dynamics in insulin exocytosis.

    PubMed

    Xu, Yingke; Toomre, Derek K; Bogan, Jonathan S; Hao, Mingming

    2017-05-25

    Type 2 diabetes is caused by defects in both insulin sensitivity and insulin secretion. Glucose triggers insulin secretion by causing exocytosis of insulin granules from pancreatic β-cells. High circulating cholesterol levels and a diminished capacity of serum to remove cholesterol from β-cells are observed in diabetic individuals. Both of these effects can lead to cholesterol accumulation in β-cells and contribute to β-cell dysfunction. However, the molecular mechanisms by which cholesterol accumulation impairs β-cell function remain largely unknown. Here, we used total internal reflection fluorescence microscopy to address, at the single-granule level, the role of cholesterol in regulating fusion pore dynamics during insulin exocytosis. We focused particularly on the effects of cholesterol overload, which is relevant to type 2 diabetes. We show that excess cholesterol reduced the number of glucose-stimulated fusion events, and modulated the proportion of full fusion and kiss-and-run fusion events. Analysis of single exocytic events revealed distinct fusion kinetics, with more clustered and compound exocytosis observed in cholesterol-overloaded β-cells. We provide evidence for the involvement of the GTPase dynamin, which is regulated in part by cholesterol-induced phosphatidylinositol 4,5-bisphosphate enrichment in the plasma membrane, in the switch between full fusion and kiss-and-run fusion. Characterization of insulin exocytosis offers insights into the role that elevated cholesterol may play in the development of type 2 diabetes. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  2. Integrated landslide monitoring: rainfalls, pore water pressures and surface movements

    NASA Astrophysics Data System (ADS)

    Berti, M.; Casula, G.; Elmi, C.; Fabris, M.; Ghirotti, M.; Loddo, F.; Mora, P.; Pesci, A.; Simoni, A.

    2003-04-01

    Rainfall-induced landslides involving clay-rich soils are widely represented in the Apennines. They cover up to 30% of the slopes forming the relief constituted by chaotic clayey units and are typically subject to repeated reactivations of the movement which are often triggered by a series of discrete failures located in the upper part (headscarp). Failures and movement can then propagate downslope and reactivate the whole landslide deposit which displays a typical elongated body, limited depth and a fan-shaped toe as a result of successive slow earth-flow like movements. An experimental monitoring programme was designed and is currently operating on the Rocca Pitigliana landslide whose characteristics well represent the above described type of movements. Its last parossistic movement date back to 1999 and, since then, remedial works were realized on behalf of local authorities. They basically consist of surficial and deep drainage works located on the landslide body. Experimental activities focus on the main headscarp whose morphology and sub-surface water circulation scheme were unaffected by the interventions. The monitoring approach includes measuring rainfalls and pore-pressure responses in both saturated and unsaturated soils. Surficial movements are continuously measured by means of GPS permanent stations and by wire extensometers which allow real time control of headscarp activity. Main aim of the monitoring activities is to provide experimental data, which can be used to test various existing hydrologic models and to identify triggering conditions. Since the ‘70s, many hydrologic models have been proposed to describe the pore water pressure distribution within the soil and its response to precipitation. The topic has recently drawn growing attention because of the recognized importance in landslide triggering but still experimental data are very much needed in order to obtain and validate capable predicting tools. This is mostly due to the multiple and

  3. Pore-pressure sensitivities to dynamic strains: observations in active tectonic regions

    USGS Publications Warehouse

    Barbour, Andrew

    2015-01-01

    Triggered seismicity arising from dynamic stresses is often explained by the Mohr-Coulomb failure criterion, where elevated pore pressures reduce the effective strength of faults in fluid-saturated rock. The seismic response of a fluid-rock system naturally depends on its hydro-mechanical properties, but accurately assessing how pore-fluid pressure responds to applied stress over large scales in situ remains a challenging task; hence, spatial variations in response are not well understood, especially around active faults. Here I analyze previously unutilized records of dynamic strain and pore-pressure from regional and teleseismic earthquakes at Plate Boundary Observatory (PBO) stations from 2006 through 2012 to investigate variations in response along the Pacific/North American tectonic plate boundary. I find robust scaling-response coefficients between excess pore pressure and dynamic strain at each station that are spatially correlated: around the San Andreas and San Jacinto fault systems, the response is lowest in regions of the crust undergoing the highest rates of secular shear strain. PBO stations in the Parkfield instrument cluster are at comparable distances to the San Andreas fault (SAF), and spatial variations there follow patterns in dextral creep rates along the fault, with the highest response in the actively creeping section, which is consistent with a narrowing zone of strain accumulation seen in geodetic velocity profiles. At stations in the San Juan Bautista (SJB) and Anza instrument clusters, the response depends non-linearly on the inverse fault-perpendicular distance, with the response decreasing towards the fault; the SJB cluster is at the northern transition from creeping-to-locked behavior along the SAF, where creep rates are at moderate to low levels, and the Anza cluster is around the San Jacinto fault, where to date there have been no statistically significant creep rates observed at the surface. These results suggest that the strength

  4. Accurate relations between pore size and the pressure of capillary condensation and the evaporation of nitrogen in cylindrical pores.

    PubMed

    Morishige, Kunimitsu; Tateishi, Masayoshi

    2006-04-25

    To examine the theoretical and semiempirical relations between pore size and the pressure of capillary condensation or evaporation proposed so far, we constructed an accurate relation between the pore radius and the capillary condensation and evaporation pressure of nitrogen at 77 K for the cylindrical pores of the ordered mesoporous MCM-41 and SBA-15 silicas. Here, the pore size was determined from a comparison between the experimental and calculated X-ray diffraction patterns due to X-ray structural modeling recently developed. Among the many theoretical relations that differ from each other in the degree of theoretical improvements, a macroscopic thermodynamic approach based on Broekhoff-de Boer equations was found to be in fair agreement with the experimental relation obtained in the present study.

  5. Capillary pressure-saturation relationships for porous granular materials: Pore morphology method vs. pore unit assembly method

    NASA Astrophysics Data System (ADS)

    Sweijen, Thomas; Aslannejad, Hamed; Hassanizadeh, S. Majid

    2017-09-01

    In studies of two-phase flow in complex porous media it is often desirable to have an estimation of the capillary pressure-saturation curve prior to measurements. Therefore, we compare in this research the capability of three pore-scale approaches in reproducing experimentally measured capillary pressure-saturation curves. To do so, we have generated 12 packings of spheres that are representative of four different glass-bead packings and eight different sand packings, for which we have found experimental data on the capillary pressure-saturation curve in the literature. In generating the packings, we matched the particle size distributions and porosity values of the granular materials. We have used three different pore-scale approaches for generating the capillary pressure-saturation curves of each packing: i) the Pore Unit Assembly (PUA) method in combination with the Mayer and Stowe-Princen (MS-P) approximation for estimating the entry pressures of pore throats, ii) the PUA method in combination with the hemisphere approximation, and iii) the Pore Morphology Method (PMM) in combination with the hemisphere approximation. The three approaches were also used to produce capillary pressure-saturation curves for the coating layer of paper, used in inkjet printing. Curves for such layers are extremely difficult to determine experimentally, due to their very small thickness and the presence of extremely small pores (less than one micrometer in size). Results indicate that the PMM and PUA-hemisphere method give similar capillary pressure-saturation curves, because both methods rely on a hemisphere to represent the air-water interface. The ability of the hemisphere approximation and the MS-P approximation to reproduce correct capillary pressure seems to depend on the type of particle size distribution, with the hemisphere approximation working well for narrowly distributed granular materials.

  6. 2D Simulations of Earthquake Cycles at a Subduction Zone Based on a Rate and State Friction Law -Effects of Pore Fluid Pressure Changes-

    NASA Astrophysics Data System (ADS)

    Mitsui, Y.; Hirahara, K.

    2006-12-01

    There have been a lot of studies that simulate large earthquakes occurring quasi-periodically at a subduction zone, based on the laboratory-derived rate-and-state friction law [eg. Kato and Hirasawa (1997), Hirose and Hirahara (2002)]. All of them assume that pore fluid pressure in the fault zone is constant. However, in the fault zone, pore fluid pressure changes suddenly, due to coseismic pore dilatation [Marone (1990)] and thermal pressurization [Mase and Smith (1987)]. If pore fluid pressure drops and effective normal stress rises, fault slip is decelerated. Inversely, if pore fluid pressure rises and effective normal stress drops, fault slip is accelerated. The effect of pore fluid may cause slow slip events and low-frequency tremor [Kodaira et al. (2004), Shelly et al. (2006)]. For a simple spring model, how pore dilatation affects slip instability was investigated [Segall and Rice (1995), Sleep (1995)]. When the rate of the slip becomes high, pore dilatation occurs and pore pressure drops, and the rate of the slip is restrained. Then the inflow of pore fluid recovers the pore pressure. We execute 2D earthquake cycle simulations at a subduction zone, taking into account such changes of pore fluid pressure following Segall and Rice (1995), in addition to the numerical scheme in Kato and Hirasawa (1997). We do not adopt hydrostatic pore pressure but excess pore pressure for initial condition, because upflow of dehydrated water seems to exist at a subduction zone. In our model, pore fluid is confined to the fault damage zone and flows along the plate interface. The smaller the flow rate is, the later pore pressure recovers. Since effective normal stress keeps larger, the fault slip is decelerated and stress drop becomes smaller. Therefore the smaller flow rate along the fault zone leads to the shorter earthquake recurrence time. Thus, not only the frictional parameters and the subduction rate but also the fault zone permeability affects the recurrence time of

  7. Simulation of the Effects of Elevated Pore Pressure on Seismicity

    NASA Astrophysics Data System (ADS)

    Foxall, W.; Johnson, S.; Hutchings, L. J.; Richards-Dinger, K. B.; Dieterich, J. H.

    2012-12-01

    Risks associated with induced seismicity are a significant factor in the design, permitting and operation of stimulation and other fluid injection operations, especially enhanced geothermal, geological CO2 sequestration and wastewater disposal. Conventional risk assessment for such operations usually neglects treatment of site-specific conditions, such as in situ stress, pore pressure evolution, and the mechanical and hydrologic properties of the reservoir. As one component of a physics-based probabilistic seismic hazard approach designed to address these issues, we discuss the development of an induced earthquake simulation method that represents hydromechanical effects explicitly. This capability is developed within the GEOS framework [Settgast and Johnson, 37th Stanford Geothermal Workshop, 2012], and is based on the earthquake simulation code RSQSim [Dieterich and Richards-Dinger, PAGEOP, 2010]. The GEOS implementation augments RSQSim by coupling an evolving pore pressure distribution into the fault response via multi-phase flow simulations of fluid injection and plume migration over relevant time scales. The present implementation is uni-directional (effective stress effects) with no feedback to the permeability response. The application allows for the use of realistic fault geometries and fractal spatial distributions of constitutive properties generated along two-dimensional fault surfaces. Constant strain rate boundary conditions are applied to mimic regional tectonic loading. RSQSim uses a rate- and state-dependent friction law to evolve the stresses along the fault. In general, significant uncertainties remain in the scaling of empirically determined constitutive parameters from laboratory to field scale, particularly at the shallow crustal depths characteristic of injection-induced seismicity. In order to understand the sensitivity of the simulations to these parameters, we have sampled multiple model realizations using Livermore's PSUADE code [Tong

  8. Robot Drills Holes To Relieve Excess Tire Pressures

    NASA Technical Reports Server (NTRS)

    Carrott, David T.

    1996-01-01

    Small, relatively inexpensive, remotely controlled robot called "tire assault vehicle" (TAV) developed to relieve excess tire pressures to protect ground crew, aircraft equipment, and nearby vehicles engaged in landing tests of CV-990 Landing System Research Aircraft. Reduces costs and saves time in training, maintenance, and setup related to "yellow" and "red" tire conditions. Adapted to any heavy-aircraft environment in which ground-crew safety at risk because of potential for tire explosions. Also ideal as scout vehicle for performing inspections in hazardous locations.

  9. Effects of coarse grain size distribution and fine particle content on pore fluid pressure and shear behavior in experimental debris flows

    NASA Astrophysics Data System (ADS)

    Kaitna, Roland; Palucis, Marisa C.; Yohannes, Bereket; Hill, Kimberly M.; Dietrich, William E.

    2016-02-01

    Debris flows are typically a saturated mixture of poorly sorted particles and interstitial fluid, whose density and flow properties depend strongly on the presence of suspended fine sediment. Recent research suggests that grain size distribution (GSD) influences excess pore pressures (i.e., pressure in excess of predicted hydrostatic pressure), which in turn plays a governing role in debris flow behaviors. We report a series of controlled laboratory experiments in a 4 m diameter vertically rotating drum where the coarse particle size distribution and the content of fine particles were varied independently. We measured basal pore fluid pressures, pore fluid pressure profiles (using novel sensor probes), velocity profiles, and longitudinal profiles of the flow height. Excess pore fluid pressure was significant for mixtures with high fines fraction. Such flows exhibited lower values for their bulk flow resistance (as measured by surface slope of the flow), had damped fluctuations of normalized fluid pressure and normal stress, and had velocity profiles where the shear was concentrated at the base of the flow. These effects were most pronounced in flows with a wide coarse GSD distribution. Sustained excess fluid pressure occurred during flow and after cessation of motion. Various mechanisms may cause dilation and contraction of the flows, and we propose that the sustained excess fluid pressures during flow and once the flow has stopped may arise from hindered particle settling and yield strength of the fluid, resulting in transfer of particle weight to the fluid. Thus, debris flow behavior may be strongly influenced by sustained excess fluid pressures controlled by particle settling rates.

  10. Investigation of Microseismicity Triggered by Raised Pore Pressure through Laboratory CO2 Injection Tests in Berea Sandstone

    NASA Astrophysics Data System (ADS)

    Lee, S.; Chang, C.

    2014-12-01

    One of the critical problems for carbon dioxide capture and storage projects is the occurrence of microseismicity due to increased pore pressure during CO2 injection. The mechanism of microseismicity can be explained by the notion that the injection-induced pore pressure increase can potentially alter the reservoir rock in the form of either creating fractures or triggering slip on pre-existing discontinuities by reducing the effective normal stress. Therefore, it is important to estimate the critical pore pressure (Pcr) to prevent excessive seismicity. The purpose of this study is to attempt to simulate the microseismicity induced from increased pore pressure by CO2 injection into Berea sandstone. Cylindrical specimens were saw-cut at 30° from the specimen axis. Specimens were either dry or saturated by tap water. The frictional coefficients of the fractures were determined from triaxial shear tests to be 0.71 (dry) and 0.65 (water-saturated). With the frictional coefficients known, we then injected CO2 (either gaseous of liquid state) into the specimens (either dry or water-saturated) subjected to triaxial stress conditions. Under the conditions of constant confining pressures and axial stresses, we increased pore pressure in steps by injecting CO2 using a syringe pump. We monitored shear slip along the fracture using axial LVDTs and microseismicity using an acoustic emission sensor. The critical pore pressure that would initiate shear slip along the fracture was calculated from the Coulomb friction law. When CO2 was injected into dry specimens, shear slip and associated microseismicity started to occur at the pore pressure levels exactly estimated from the Coulomb theory. However, when CO2 (both gaseous and liquid states) was injected into water-saturated specimens, the same were initiated at pore pressures slightly higher (by 1.2-3.7 MPa) than that estimated from the Coulomb friction law. These results suggest that the presence of water and associated water

  11. Some specifics of influence of pore pressure on physical properties of deformable rocks

    NASA Astrophysics Data System (ADS)

    Sobolev, G. A.; Stakhovskaya, Z. I.; Mikayelyan, A. O.

    1984-07-01

    A study was made of a range of problems related to the physical and mechanical properties of limestones from the region of the Ingura hydroelectric powerplant under hydrostatic pore pressure with additional axial pressure. The purpose was to estimate the significance and effect of pore pressure on physical properties in rocks as a function of the stressed state under conditions of hydrostatic pressure and hydrostatic pressure with additional axial loading. The P wave velocity, resistivity and longitudinal deformation were measured under pressure with specimens which had been carefully dried and saturated under vacuum conditions with a 2 n solution of NaCl. Cyclical variations of pore pressure were found to cause compaction of the rock. Cyclical variations of pore pressure under complex stress conditions facilitate fracture and strength loss of the rock.

  12. Sensitivity of stress inversion of focal mechanisms to pore pressure changes

    NASA Astrophysics Data System (ADS)

    Martínez-Garzón, Patricia; Vavryčuk, Václav; Kwiatek, Grzegorz; Bohnhoff, Marco

    2016-08-01

    We investigate the sensitivity of stress inversion from focal mechanisms to pore pressure changes. Synthetic tests reveal that pore pressure variations can cause apparent changes in the retrieved stress ratio R relating the magnitude of the intermediate principal stress with respect to the maximum and minimum principal stresses. Pore pressure and retrieved R are negatively correlated when R is low (R < 0.6). The spurious variations in retrieved R are suppressed when R > 0.6. This observation is independent of faulting style, and it may be related to different performance of the fault plane selection criterion and variability in orientation of activated faults under different pore pressures. Our findings from synthetic data are supported by results obtained from induced seismicity at The Geysers geothermal field. Therefore, the retrieved stress ratio variations can be utilized for monitoring pore pressure changes at seismogenic depth in stress domains with overall low R.

  13. Small-pore, big opportunity: searching for novel applications of small-pore zeolites by means of pressure and temperature

    NASA Astrophysics Data System (ADS)

    Im, J.; Lee, Y.

    2013-12-01

    Pressure-induced structural and chemical changes observed in small-pore zeolite natrolites are especially encouraging in terms of finding appropriate applications as they occur in the industrially-achievable low-pressure regime, i.e., as low as a few kilobars. After identifying the systematics of structural and chemical behaviors of natrolites in relation to the composition of pressure media, we have developed a procedure to exchange and sequestrate both Cs cation and I anion under intermediate pressure and temperature conditions. This result points towards the possibility of designing novel storage means for important radionuclides. Another avenue to utilize the unique pressure-induced chemistry of small-pore zeolite natrolite is to trap nominally non-adsorbable gas molecules via auxetic expansion under pressure. We have recently succeeded in pressure-induced insertion of Xe into silver-natrolite. Intriguingly, Xe adsorption occurs concomitant with charge disproportionation of silver cations to form silver nano-blobs on the surface of natrolite crystals. We will also present here various usages of laboratory-based high-pressure devices and characterization tools, which play important roles to confirm the synchrotron-based high-pressure experiments involving synthesis of new materials.

  14. Effect of pore pressure on the velocity of compressional waves in low-porosity rocks.

    NASA Technical Reports Server (NTRS)

    Todd, T.; Simmons, G.

    1972-01-01

    The velocity V sub p of compressional waves has been measured in rock samples of low porosity to confining pressures P sub c of 2 kb for a number of different constant pore pressures P sub p. An effective pressure defined by P sub e = P sub c-nP sub p, n less than or equal to 1, is found to be the determining factor in the behavior of V sub p rather than an effective pressure defined simply by the differential pressure Delta P = P sub c-P sub p. As pore pressure increases at constant effective pressure, the value of n increases and approaches 1, but as effective pressure increases at constant pore pressure, the value of n decreases. These observations are consistent with Biot's theory of the propagation of elastic waves in a fluid-saturated porous solid.

  15. Experimental study on the response characteristics of coal permeability to pore pressure under loading and unloading conditions

    NASA Astrophysics Data System (ADS)

    Ye, Zhiwei; Zhang, Lei; Hao, Dingyi; Zhang, Cun; Wang, Chen

    2017-10-01

    In order to study the response characteristics of coal permeability to pore pressure, seepage experiments under different simulated in situ stresses on loading and unloading paths are carried out using the self-developed Gas Flow and Displacement Testing Apparatus (GFDTA) system. Based on the analysis of the experimental data, the relationship between average pore pressure and permeability is found to basically obey the function distribution of a two degree polynomial. In this paper, two aspects of the relationship between permeability and pore pressure are explained: the Klinbenberg effect and expansion, and the penetration of the initial fracture. Under low pore pressure, the decrease in the Klinbenberg effect is the main reason for the decrease in permeability with increased pore pressure. Under relatively high pore pressure, the increase in pore pressure leads to the initial fracture expansion and penetration of the coal sample, which causes an increase in permeability. In order to evaluate the sensitivity of the permeability response to pore pressure changes, the permeability dispersion and pore pressure sensitivity coefficients are defined. After the sensitivity analysis, it was concluded that the loading history changed the fracture structure of the original coal sample and reduced its permeability sensitivity to pore pressure. Under low pore pressure, the Klinbenberg effect is the reason for the decrease in pore pressure sensitivity. Lastly, the permeability-pore pressure relationship is divided into three stages to describe the different response characteristics individually.

  16. Diminished pore pressure in low-porosity crystalline rock under tensional failure: Apparent strengthening by dilatancy

    NASA Astrophysics Data System (ADS)

    Schmitt, Douglas R.; Zoback, Mark D.

    1992-01-01

    Rupture tests on internally pressurized, thin-walled hollow cylinders of Westerly granite with impermeable inner membranes suggest that the conventional, or Terzaghi, effective stress law does not describe tensile failure at high internal pressurization rates near 6 MPa/s. Unjacketed and saturated samples, with an initial pore pressure and for which the inner cavity pressure was increased rapidly with respect to the diffusivity, display substantially increased apparent tensile strengths and deformational moduli much higher than similarly configured but more slowly pressurized tests. Alternatively, the properties of completely dry test pieces with no pore pressure show little, if any, dependence on pressurization rate. Further, the behavior of the rapid unjacketed tests was similar to that for completely dry samples. These observations cannot be explained by the predicted undrained response, but they provide indirect evidence for diminished pore pressure effects reminiscent of dilatant hardening observed in compressive failure experiments. Calculated pore pressure diffusion rates support this suggestion as pore pressure perturbations cannot be damped out on the time scale of the rapidly pressurized tests. It is not clear if these effects are produced by elastic microcrack dilatancy, of which the nonlinear stress-strain curve of granites is symptomatic, or the irreversible production of new porosity as in compressive shear failure tests.

  17. Effects of intermediate wettability on entry capillary pressure in angular pores.

    PubMed

    Rabbani, Harris Sajjad; Joekar-Niasar, Vahid; Shokri, Nima

    2016-07-01

    Entry capillary pressure is one of the most important factors controlling drainage and remobilization of the capillary-trapped phases as it is the limiting factor against the two-phase displacement. It is known that the entry capillary pressure is rate dependent such that the inertia forces would enhance entry of the non-wetting phase into the pores. More importantly the entry capillary pressure is wettability dependent. However, while the movement of a meniscus into a strongly water-wet pore is well-defined, the invasion of a meniscus into a weak or intermediate water-wet pore especially in the case of angular pores is ambiguous. In this study using OpenFOAM software, high-resolution direct two-phase flow simulations of movement of a meniscus in a single capillary channel are performed. Interface dynamics in angular pores under drainage conditions have been simulated under constant flow rate boundary condition at different wettability conditions. Our results shows that the relation between the half corner angle of pores and contact angle controls the temporal evolution of capillary pressure during the invasion of a pore. By deviating from pure water-wet conditions, a dip in the temporal evolution of capillary pressure can be observed which will be pronounced in irregular angular cross sections. That enhances the pore invasion with a smaller differential pressure. The interplay between the contact angle and pore geometry can have significant implications for enhanced remobilization of ganglia in intermediate contact angles in real porous media morphologies, where pores are very heterogeneous with small shape factors. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Pore pressure prediction in laminated shaly sand reservoir: A case study of Bintuni Basin

    NASA Astrophysics Data System (ADS)

    Haris, A.; Parlindungan, E.; Riyanto, A.

    2017-07-01

    Pore pressure prediction has been carried out using well log and seismic velocity data to evaluate pore pressure character of the laminated shally sand reservoir in Bintuni Basin, West Papua. The majority of the thin laminated reservoir are below resolving power of logging tool. The main factor of reservoir behavior, which typically exhibits composition mineral of lithic, micaceous and glauconitic, has a strong relationship with conductive mineral. Based on total gas mud logging data, there is some potential gas reservoir. In this study, non-normal high pore pressure was identified in some intervals and designed for cases where compaction disequilibrium is the cause of fluid expansion on the compaction state of the impermeable sediments. We used Eaton's method to estimate pore pressure gradient. We also performed seismic velocity model analysis to estimate the effective stress using empirical Bowers and Terzaghi method, where horizontal and vertical pressure data were distributed using probabilistic neural network method. Our analysis on the pore pressure distribution map, which is combined with the time structure, shows that the correlation of non normal pore pressure is found not only in height structure but also in the low structure, particularly at the southern part of the study area.

  19. Strain and pore pressure propagation in a water-saturated porous medium

    NASA Astrophysics Data System (ADS)

    van der Grinten, Jos G. M.; van Dongen, Marinus E. H.; van der Kogel, Hans

    1987-12-01

    Wave propagation in a water-saturated porous column consisting of fixed sand particles is studied by means of a shock tube technique. Pore pressures and axial strains are recorded simultaneously. The measurements show a coincident compression of pore fluid and porous column during the passage of the first wave. Due to the second wave the pore fluid is compressed while the porous material expands. This observed behavior is in agreement with theoretical predictions. The introduction of a frequency-dependent permeability and an effective pore radius based on a cylindrical duct model yields an improved description of the damping of the second wave.

  20. Effect of Processing Pressure on Isolated Pore Formation during Controlled Directional Solidification in Small Channels

    NASA Technical Reports Server (NTRS)

    Cox, Matthew C.; Anilkumar, Amrutur V.; Grugel, RIchard N.; Lee, Chun P.

    2008-01-01

    Directional solidification experiments were performed, using succinonitrile saturated with nitrogen gas, to examine the effects of in-situ processing pressure changes on the formation growth, and evolution of an isolated, cylindrical gaseous pore. A novel solidification facility, capable of processing thin cylindrical samples (I.D. < 1.0 mm), under controlled pressure conditions, was used for the experiments. A new experimental method for growing the isolated pore from a seed bubble is introduced. The experimental results indicate that an in-situ processing pressure change will result in either a transient change in pore diameter or a complete termination of pore growth, indicating that pressure changes can be used as a control parameter to terminate bubble growth. A simple analytical model has been introduced to explain the experimental observations.

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    Ion-track membranes (ITM) are known as polymer films with straight pore channels the size, shape, orientation and density of which can be precisely controlled. Previous ultrasonic studies of ITM using air-coupled and wide-band ultrasound pulses (0.1-5.0 MHz) revealed the possibility to isolate and study ultrasound propagation in these pores. Hence a novel ultrasonic technique has been established to determine pore characteristics of ITM using this pore propagation mode. In this work, we present a modification of the technique based on the use of pressurized air. This is achieved by enclosing transducers and samples in a pressurized chamber (1-9 bar). The main objective of this study is to reduce the attenuation of the ultrasound waves propagating in the pores and to increase the coupling of the ultrasonic energy into this pore propagation mode at the membrane surface in order to extend the applicability range of the existing technique to the characterization of ITM with small pores (diameter < 200 nm), or with very low porosity (<5%), or with pores with partially closed aperture at the membrane surface, or in pores with a more complex geometry, where use of air-coupled ultrasound at room conditions may present some drawbacks.

  2. Hydrodynamic Stresses Driving Pore Pressure Changes in Sandy Coastal Sediments

    DTIC Science & Technology

    1998-09-30

    and Foda , 1981, Bennett et al. 1982, 1992a and b). The environmental measurements, sediment data, and in situ electrical conductivity and pore...Geotechnical Properties in Surficial Marine Sediments: Gulf of Mexico Continental Shelf, NOARL Rpt. ID 020:360:92, 41p. Bennett, R. H., W. A. Dunlap...April-May 1997, SEAPROBE Technical Report, December 1997, 24p. plus figures and tables. Mei, C.C. and M.A. Foda ., 1981. Wave-Induced Responses in a

  3. Pore-pressure gradients in the proximity of a submarine buried pipeline

    SciTech Connect

    Magda, W.

    1995-12-31

    This paper is concerned with the two-dimensional finite-element modeling of the wave-induced pore-pressure field in the proximity of a submarine pipeline buried in sandy seabed sediments subject to continuous loading of regular surface waves. Neglecting inertial forces, a linear elastic stress-strain relationship for the soil, and Darcy`s law for the flow of pore-fluid are assumed. The model takes into account the compressibility of both components (i.e., pore-fluid and soil skeleton) of the two-phase medium. The results of numerical computations are discussed with respect to the hydraulic gradient in the upper part of seabed sediments just above the buried submarine pipeline. The pore-pressure gradient is studied as a function of geometry (depth of burial) as well as soil and pore-fluid compressibility parameters where the later of which is defined in terms of soil saturation conditions.

  4. Pore pressure prediction and well bore stability analysis in Lower Paleozoic shale formation, N Poland

    NASA Astrophysics Data System (ADS)

    Słota-Valim, Małgorzata

    2017-04-01

    Pore pressure and wellbore stability sometimes pose a serious challenge while drilling, especially through rock formations of reduced strength or through intervals where abnormally high pore pressure was formed. Lack of prediction of pore pressure and lack of wellbore stability analysis introduce an element of uncertainty in selection of drilling fluid density. Too low density of drilling fluid can lead to uncontrolled flow of the reservoir fluid to the wellbore (kicks), washouts and occurrence of cavern like structures called breakouts. On the other hand too high density can lead to formation fracturing and further fluid loss. Therefore wellbore stability loss frequently prolongs the operating time, rising the costs of the drilling and in severe cases may end up well abandons loss. The above mentioned complications can be avoided or greatly reduced by reliable analysis of drilling conditions with the aspects to geomechanical characteristics of drilled rock formations. This study presents the results of analysis of pore pressure performed with the use of commonly used in oil industry methods. The analysis of pore pressure was carried out in almost entire profile of four boreholes drilled through lower Paleozoic shales, deposited in the southern part of the Baltic Basin. In addition wellbore stability analysis was performed in the well with most complete geomechanical input data base. Obtained results helped identifying intervals with elevated pore pressure could pose a risk during drilling operation. Elaborated 1D geomechanical model provides safe mud weight window helping to reduce the instabilities risk and constitute a great tool for geomechanical model validation.

  5. Nucleation of slip-weakening rupture instability in landslides by localized increase of pore pressure

    NASA Astrophysics Data System (ADS)

    Viesca, Robert C.; Rice, James R.

    2012-03-01

    We model landslide initiation as slip surface growth driven by locally elevated pore pressure, with particular reference to submarine slides. Assuming an elastic medium and friction that weakens with slip, solutions exist in which the slip surface may dynamically grow, without further pore pressure increases, at a rate of the order of the sediment shear wave speed, a situation comparable to earthquake nucleation. The size of the rupture at this transition point depends weakly on the imposed pore pressure profile; however, the amount of slip at the transition depends strongly on whether the pore pressure was broadly or sharply elevated. Sharper profiles may result in pore pressures reaching the total slope-normal stress before dynamic rupture is nucleated. While we do not account for modes of failure other than pure slip on a failure surface, this may be an indication that additional modes involving liquefaction or hydraulic cracking may be factors in the initiation of shallow slope failure. We identify two length scales, one geometrical (h, depth below the free surface) and one material (ℓ, determined by the frictional weakening rate) and a transition in nucleation behavior between effectively "deep" and "shallow" limits dependent on their ratio. Whether dynamic propagation of failure is indefinite or arresting depends largely on whether the background shear stress is closer to nominal peak or residual frictional strength. This is determined in part by background pore pressures, and to consider the submarine case we simplify a common sedimentation/consolidation approach to reflect interest in near-seafloor conditions.

  6. Pore pressure control on faulting behavior in a block-gouge system

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Juanes, R.

    2016-12-01

    Pore fluid pressure in a fault zone can be altered by natural processes (e.g., mineral dehydration and thermal pressurization) and industrial operations involving subsurface fluid injection/extraction for the development of energy and water resources. However, the effect of pore pressure change on the stability and slip motion of a preexisting geologic fault remain poorly understood; yet they are critical for the assessment of seismic risk. In this work, we develop a micromechanical model to investigate the effect of pore pressure on faulting behavior. The model couples pore network fluid flow and mechanics of the solid grains. We conceptualize the fault zone as a gouge layer sandwiched between two blocks; the block material is represented by a group of contact-bonded grains and the gouge is composed of unbonded grains. A pore network is extracted from the particulate pack of the block-gouge system with pore body volumes and pore throat conductivities calculated rigorously based on the geometry of the local pore space. Pore fluid exerts pressure force onto the grains, the motion of which is solved using the discrete element method (DEM). The model updates the pore network regularly in response to deformation of the solid matrix. We study the fault stability in the presence of a pressure inhomogeneity (gradient) across the gouge layer, and compare it with the case of homogeneous pore pressure. We consider both normal and thrust faulting scenarios with a focus on the onset of shear failure along the block-gouge interfaces. Numerical simulations show that the slip behavior is characterized by intermittent dynamics, which is evident in the number of slipping contacts at the block-gouge interfaces and the total kinetic energy of the gouge particles. Numerical results also show that, for the case of pressure inhomogeneity, the onset of slip occurs earlier for the side with higher pressure, and that this onset appears to be controlled by the maximum pressure of both sides

  7. Sudden pore pressure rise and rapid landslide initiation induced under extreme rainfall conditions - a case study

    NASA Astrophysics Data System (ADS)

    Fukuoka, Hiroshi; Wang, Fawu; Wang, Gonghui

    2010-05-01

    sliding surface of one of the upstream small-scale landslides. Those contained finer grains and lower permeability rather than the one sampled in the Hiroshima case. Sample was consolidated by smaller stress corresponding to the site condition, and saturated by overnight circulating de-aired water. Normal stress and shear stress corresponding the slope condition was given, then, pore pressure (back pressure) was raised artificially at constant rate. When the effective stress reached the failure line, suddenly measured pore pressure monitored at about 2 mm above the shear plane, quickly increased. This sudden change abruptly accelerate the shear displacement. Stress condition soon reached the steady state and remained there thereafter. The reason of the excess pore pressure generation was the negative dilatancy, following a slight positive dilatancy. Most of the negative dilatancy could be explained by collapse of loose soil skelton as well as grain crushing during deformation and shearing.

  8. Quaternary Sediment Accumulation in the Aleutian Trench: Implications for Dehydration Reaction Progress and Pore Pressure Development Offshore Alaska

    NASA Astrophysics Data System (ADS)

    Meridth, L. N.; Screaton, E.; Jaeger, J. M.; James, S. R.; Villaseñor, T. G.

    2015-12-01

    Sediment inputs to subduction zones impart a significant control on diagenetic reaction progress, fluid production and pore pressure development and thus affect hydrologic and tectonic behavior during subduction. Intensified glaciation following the mid-Pleistocene transition increased sediment flux to the Gulf of Alaska. Rapid sediment accumulation (>1 km/my) in the Aleutian Trench increases overburden and should accelerate dehydration of hydrous sedimentary components by elevating temperatures in the incoming sediment column. These processes have the potential to generate fluid overpressures in the mud-dominated, low permeability sediments deposited on the incoming plate, offshore SE Alaska. Mineralogical analyses on incoming sediments from Deep Sea Drilling Project Leg 18 and Integrated Ocean Drilling Program Expedition 341 show that both smectite and Opal-A are present as hydrous mineral phases. A 1-D numerical model was developed to track dehydration reaction progress and pore pressures in the incoming sediment column from the abyssal plain to the Aleutian Trench. Simulated temperatures in the incoming column increase due to the insulating effect of trench sediments. As a result, trench sedimentation causes smectite dehydration to begin and Opal-A dehydration to nearly reach completion at the deformation front. Simulated excess pore pressures in the proto-decollement zone increase from nearly hydrostatic to almost half of lithostatic due to the rapid deposition of trench sediments. The 1-D modeling results were incorporated into a 2-D model that follows the underthrust column at the deformation front into the subduction zone. Simulated results of the 2-D flow model illustrate the effects of lateral flow on pore pressure distribution following subduction.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Earthquake-induced groundwater changes which are the pre- and co-seismic changes have been long reported (e.g. Roeloffs, 1996). For example, 1995 Kobe earthquake, water inflow into observation tunnel changed at Rokko (Fujimori et al., 1995), at the times of 1964 Alaska earthquake (M8.6) (Coble, 1967) and 1999 Taiwan Chi-Chi earthquake (M7.6) (Chia et al., 2001), groundwater leve were fluctuated. The shaking of seismic waves and crack formation by crustal deformation are proposed as one causes but the mechanism is controversial. We are monitoring pore pressure from 2005 to measure the stress changes at Kamioka mine, Gifu prefecture, central Japan. Barometric pressure and strain are observed to correct the pore pressure data. In general, the pore pressure changes associate with the meteorological effects, Earth tides and crustal deformation. Increase of pore pressure depends on the precipitation which flows into the ground. Especially, snow effects are bigger than the usual rainfall because our observation site has heavy snow in winter season. Melted snow flows in the ground and pore pressure increases at the March to April every year. When the 2011 Tohoku earthquake (M9.0) occurred, pore pressure remarkably decreased because the permeability increases by crustal deformation at Kamioka region. Thus, we estimated the hydraulic diffusivity before and after the earthquake from pore pressure response to crustal deformation. We made separated analyses on three frequency bands. First is the high frequency band, especially, seismic response. Second is response to Earth tides. Third frequency band is that of barometric response which is lower than other two bands. At high frequency band, we confirmed that the deformation occurred under undrained condition and estimated the bulk modulus from pore pressure and strain data. Next, tidal response is extracted from pore pressure which applied to every three months data of pore pressure, barometric pressure and strain. Time window

  10. Temporal and Spatial Pore Water Pressure Distribution Surrounding a Vertical Landfill Leachate Recirculation Well

    PubMed Central

    Kadambala, Ravi; Townsend, Timothy G.; Jain, Pradeep; Singh, Karamjit

    2011-01-01

    Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth. PMID:21655145

  11. Temporal and spatial pore water pressure distribution surrounding a vertical landfill leachate recirculation well.

    PubMed

    Kadambala, Ravi; Townsend, Timothy G; Jain, Pradeep; Singh, Karamjit

    2011-05-01

    Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.

  12. Pore pressure changes induced by slip on permeable and impermeable faults

    NASA Astrophysics Data System (ADS)

    Rudnicki, J. W.; Hsu, Tze-Chi

    1988-04-01

    Pore pressure changes due to a ramp introduction of slip on permeable and impermeable faults in a fluid-saturated rock mass are calculated for the purpose of evaluating water well level fluctuations. The calculations demonstrate the importance of coupling between deformation and fluid diffusion at observation points less than 5(4ct0)½, where c is the diffusivity and t0 is the rise time. The decay of pore pressure in the results here is due entirely to fluid mass diffusion. An approach that neglects diffusion and assumes that the pore pressure is proportional to the mean normal stress would predict a ramp pore pressure response. At distances greater than 5(4ct0)½ the pore pressure decays so slowly that the neglect of diffusion may be appropriate. For both permeable and impermeable faults, the pore pressure decays more rapidly for shorter slip zone lengths and longer rise times. However, the pore pressure change calculated for the impermeable fault is larger, particularly for observation points near the fault, and decays less rapidly than for the permeable fault. These differences suggest that fault permeability can be a significant factor in the response of water wells near faults and care should be used in inferring details of the slip distribution if hydrologic conditions are not known. These results are applied to a water well level change observed by Lippincott et al. A satisfactory fit to the data is obtained by uniform slip over a fault length of about 1.5 km and a rise time of 8 hours. Although the slip magnitude is not well constrained by the fit, the range of possible values includes the 0.5 to 1.0 cm inferred by Lippincott et al. using a different approach.

  13. Number of connecting path and tortuosity information of 3 dimensional pore networks in pressurized clastic sandstone

    NASA Astrophysics Data System (ADS)

    Takahashi, M.; Ahn, C.; Park, H.; Experimental Geoscience Research Team

    2010-12-01

    The permeability of a geologic material is dependent on the porosity of the material and the degree of connectivity between pores. The specific storage of geologic materials is dependent on the porosity of the material and the compressibility of both the material and the included fluid; accordingly, both the permeability and specific storage of geologic materials vary over wide ranges. The three dimensional geometry and connectivity of pore network play a fundamental role in governing fluid transport properties of porous media. The spatial and three-dimensional information of pore geometry is difficult to obtain under pressurized conditions. We try to investigate the pressure dependence on geometrical information of pore space in rock specimen by means of micro focus X-ray CT data. In this paper, we use the three-dimensional medial axis (3DMA) method of Lindquist et al. (2000) to quantify the flow relevant geometric properties of the pore structure in Shirahama sandstone, clastic sandstone in Japan. We present the effect of the hydrostatic pressure on permeability using the transient pulse method and giving a quantitative characterization of pore networks in intact clastic sandstone and clastic sandstone pressurized to 25 MPa. The measured frequencies for throats and pores decreased remarkably under the stressed condition. It is clear that permeability reduction as the hydrostatic pressure increases is attributable to the decrease in the population of pores with a radius of 20-90 micron, decrease in the population of throats with a radius of 10-50 micron, and increase in tortuosity in the X and Z directions. This phenomenon has already been confirmed by theory and many experiments, but the three-dimensional geometry of throats and pores has not been investigated in detail. Ultimately, we can obtain three-dimensional visualizations. In addition, we present the changes in tortuosity in three directions for intact and stressed samples. In each direction, the

  14. The change in orientation of subsidiary shears near faults containing pore fluid under high pressure

    USGS Publications Warehouse

    Byerlee, J.

    1992-01-01

    Byerlee, J., 1992. The change in orientation of subsidiary shears near faults containing pore fluid under high pressure. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 295-303. The mechanical effects of a fault containing near-lithostatic fluid pressure in which fluid pressure decreases monotonically from the core of the fault zone to the adjacent country rock is considered. This fluid pressure distribution has mechanical implications for the orientation of subsidiary shears around a fault. Analysis shows that the maximum principal stress is oriented at a high angle to the fault in the country rock where the pore pressure is hydrostatic, and rotates to 45?? to the fault within the fault zone where the pore pressure is much higher. This analysis suggests that on the San Andreas fault, where heat flow constraints require that the coefficient of friction for slip on the fault be less than 0.1, the pore fluid pressure on the main fault is 85% of the lithostatic pressure. The observed geometry of the subsidiary shears in the creeping section of the San Andreas are broadly consistent with this model, with differences that may be due to the heterogeneous nature of the fault. ?? 1992.

  15. Fluid displacement fronts in porous media: pore scale interfacial jumps, pressure bursts and acoustic emissions

    NASA Astrophysics Data System (ADS)

    Moebius, Franziska; Or, Dani

    2014-05-01

    The macroscopically smooth and regular motion of fluid fronts in porous media is composed of numerous rapid pore-scale interfacial jumps and pressure bursts that involve intense interfacial energy release in the form of acoustic emissions. The characteristics of these pore scale events affect residual phase entrapment and transport properties behind the front. We present experimental studies using acoustic emission technique (AE), rapid imaging, and liquid pressure measurements to characterize these processes during drainage and imbibition in simple porous media. Imbibition and drainage produce different AE signatures (AE amplitudes obey a power law). For rapid drainage, AE signals persist long after cessation of front motion reflecting fluid redistribution and interfacial relaxation. Imaging revealed that the velocity of interfacial jumps often exceeds front velocity by more than 50 fold and is highly inertial component (Re>1000). Pore invasion volumes reduced deduced from pressure fluctuations waiting times (for constant withdrawal rates) show remarkable agreement with geometrically-deduced pore volumes. Discrepancies between invaded volumes and geometrical pores increase with increasing capillary numbers due to constraints on evacuation opportunity times and simultaneous invasion events. A mechanistic model for interfacial motions in a pore-throat network was developed to investigate interfacial dynamics focusing on the role of inertia. Results suggest that while pore scale dynamics were sensitive to variations in pore geometry and boundary conditions, inertia exerted only a minor effect on phase entrapment. The study on pore scale invasion events paints a complex picture of rapid and inertial motions and provides new insights on mechanisms at displacement fronts that are essential for improved macroscopic description of multiphase flows in porous media.

  16. Evolution of pore fluid pressures in a stimulated geothermal reservoir inferred from earthquake focal mechanisms

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Deichmann, N.

    2014-12-01

    We developed an inversion method to estimate the evolution of pore fluid pressure fields from earthquake focal mechanism solutions based on the Bayesian statistical inference and Akaike's Bayesian information criterion (ABIC). This method's application to induced seismicity in the Basel enhanced geothermal system in Switzerland shows the evolution of pore fluid pressures in response to fluid injection experiments. For a few days following the initiation of the fluid injection, overpressurized fluids are concentrated around the borehole and then anisotropically propagate within the reservoir until the bleed-off time. Then, the pore fluid pressure in the vicinity of the borehole drastically decreases, and overpressurized fluids become isolated in a few major fluid pockets. The pore fluid pressure in these pockets gradually decreases with time. The pore fluid pressure in the reservoir is less than the minimum principal stress at each depth, indicating that the hydraulic fracturing did not occur during stimulation. This suggests that seismic events may play an important role to promote the development of permeable channels, particularly southeast of the borehole where the largest seismic event (ML 3.4) occurred. This is not directly related to a drastic decrease in fault strength at the hypocenter, but rather the positive feedback between permeability enhancement and poro-elastic and stress transfer loading from slipping interfaces. These processes likely contribute to this event's nucleation.

  17. Capillary pressure across a pore throat in the presence of surfactants

    NASA Astrophysics Data System (ADS)

    Jang, Junbong; Sun, Zhonghao; Santamarina, J. Carlos

    2016-12-01

    Capillarity controls the distribution and transport of multiphase and immiscible fluids in soils and fractured rocks; therefore, capillarity affects the migration of nonaqueous contaminants and remediation strategies for both LNAPLs and DNAPLs, constrains gas and oil recovery, and regulates CO2 injection and geological storage. Surfactants alter interfacial tension and modify the invasion of pores by immiscible fluids. Experiments are conducted to explore the propagation of fluid interfaces along cylindrical capillary tubes and across pore constrictions in the presence of surfactants. Measured pressure signatures reflect the interaction between surface tension, contact angle, and the pore geometry. Various instabilities occur as the interface traverses the pore constriction, consequently, measured pressure signatures differ from theoretical trends predicted from geometry, lower capillary pressures are generated in advancing wetting fronts, and jumps are prone to under-sampling. Contact angle and instabilities are responsible for pronounced differences between pressure signatures recorded during advancing and receding tests. Pressure signatures gathered with surfactant solutions suggest changes in interfacial tension at the constriction; the transient surface tension is significantly lower than the value measured in quasi-static conditions. Interface stiffening is observed during receding fronts for solutions near the critical micelle concentration. Wetting liquids tend to form plugs at pore constrictions after the invasion of a nonwetting fluid; plugs split the nonwetting fluid into isolated globules and add resistance against fluid flow.

  18. Effects of Pore Distributions on Ductility of Thin-Walled High Pressure Die-Cast Magnesium

    SciTech Connect

    Choi, Kyoo Sil; Li, Dongsheng; Sun, Xin; Li, Mei; Allison, John

    2013-06-01

    In this paper, a microstructure-based three-dimensional (3D) finite element modeling method is adopted to investigate the effects of porosity in thin-walled high pressure die-cast (HPDC) Magnesium alloys on their ductility. For this purpose, the cross-sections of AM60 casting samples are first examined using optical microscope and X-ray tomography to obtain the general information on the pore distribution features. The experimentally observed pore distribution features are then used to generate a series of synthetic microstructure-based 3D finite element models with different pore volume fractions and pore distribution features. Shear and ductile damage models are adopted in the finite element analyses to induce the fracture by element removal, leading to the prediction of ductility. The results in this study show that the ductility monotonically decreases as the pore volume fraction increases and that the effect of ‘skin region’ on the ductility is noticeable under the condition of same local pore volume fraction in the center region of the sample and its existence can be beneficial for the improvement of ductility. The further synthetic microstructure-based 3D finite element analyses are planned to investigate the effects of pore size and pore size distribution.

  19. Undrained heating and anomalous pore-fluid pressurization of a hardened cement paste

    NASA Astrophysics Data System (ADS)

    Ghabezloo, S.; Sulem, J.; Saint-Marc, J.

    2009-04-01

    Temperature increase in a fluid-saturated porous material in undrained condition leads to volume change and pore pressure increase due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the pore volume. This increase of the pore fluid pressure induces a reduction of the effective mean stress, and can lead to shear failure or hydraulic fracturing. This phenomenon is important is important in environmental engineering for radioactive (exothermal) waste disposal in deep clay geological formations as well as in geophysics in the studies of rapid fault slip events when shear heating tends to increase the pore pressure and to decrease the effective compressive stress and the shearing resistance of the fault material (Sulem et al. 2007). This is also important in petroleum engineering where the reservoir rock and the well cement lining undergo sudden temperature changes for example when extracting heavy oils by steam injection methods. This rapid increase of temperature could damage cement sheath integrity of wells and lead to loss of zonal isolation. The values of the thermal pressurization coefficient, defined as the pore pressure increase due to a unit temperature increase in undrained condition, is largely dependent upon the nature of the material, the state of stress, the range of temperature change, the induced damage. The large variability of the thermal pressurization coefficient reported in the literature for different porous materials with values from 0.01MPa/°C to 1.5MPa/°C highlights the necessity of laboratory studies. This phenomenon of thermal pressurization is studied experimentally for a fluid-saturated hardened cement paste in an undrained heating test. Careful analysis of the effect of the dead volume of the drainage system of the triaxial cell has been performed based on a simple correction method proposed by Ghabezloo and Sulem (2008, 2009). The drained and undrained thermal expansion coefficients of the hardened

  20. Prediction of pore-water pressure response to rainfall using support vector regression

    NASA Astrophysics Data System (ADS)

    Babangida, Nuraddeen Muhammad; Mustafa, Muhammad Raza Ul; Yusuf, Khamaruzaman Wan; Isa, Mohamed Hasnain

    2016-11-01

    Nonlinear complex behavior of pore-water pressure responses to rainfall was modelled using support vector regression (SVR). Pore-water pressure can rise to disturbing levels that may result in slope failure during or after rainfall. Traditionally, monitoring slope pore-water pressure responses to rainfall is tedious and expensive, in that the slope must be instrumented with necessary monitors. Data on rainfall and corresponding responses of pore-water pressure were collected from such a monitoring program at a slope site in Malaysia and used to develop SVR models to predict pore-water pressure fluctuations. Three models, based on their different input configurations, were developed. SVR optimum meta-parameters were obtained using k-fold cross validation and a grid search. Model type 3 was adjudged the best among the models and was used to predict three other points on the slope. For each point, lag intervals of 30 min, 1 h and 2 h were used to make the predictions. The SVR model predictions were compared with predictions made by an artificial neural network model; overall, the SVR model showed slightly better results. Uncertainty quantification analysis was also performed for further model assessment. The uncertainty components were found to be low and tolerable, with d-factor of 0.14 and 74 % of observed data falling within the 95 % confidence bound. The study demonstrated that the SVR model is effective in providing an accurate and quick means of obtaining pore-water pressure response, which may be vital in systems where response information is urgently needed.

  1. Temperature and pore pressure distribution in a concrete slab during the microwave decontamination process

    SciTech Connect

    Li, W.; Ebadian, M.A.; White, T.L.; Grubb, R.G.; Foster, D. Jr.

    1994-10-01

    As an application of microwave engineering, the new technology of concrete decontamination and decommissioning using microwave energy has been recently developed. The temperature and pore pressure within the concrete are studied theoretically in this paper. The heat and mass transfer within the porous concrete, coupled with temperature dependent dielectric property are investigated. The effects of microwave frequency (f), microwave power intensity (Q{sub 0,ave}), concrete porosity ({phi}) on the temperature and pore pressure distributions and their variations are fully discussed. The effects of the variation of complex dielectric permittivity ({epsilon}) and presentation of different steel reinforcements are also illustrated.

  2. Pore pressure behavior at the shut-in phase and causality of large induced seismicity at Basel, Switzerland

    NASA Astrophysics Data System (ADS)

    Mukuhira, Y.; Dinske, C.; Asanuma, H.; Ito, T.; Häring, M. O.

    2017-01-01

    Induced seismicity with unexpectedly large magnitude often occurs after shut-in or end of stimulation, generating concerns at the end of stimulation. We investigated the physical mechanism of large-magnitude induced seismicity during shut-in following the hydraulic stimulation at Basel, Switzerland. Larger postinjection events occurred at the periphery of the seismic cloud. We estimated the pore pressure required to cause shear slip using Coulomb failure criteria from stress information, geometry of the fault planes of microseismic events, and a constant coefficient of friction. Time series analysis of pore pressure distribution indicated that pore pressure migrated to the far field even after shut-in. Redistribution of pore pressure at shut-in brought sufficient pore pressure increase to induce seismicity in the peripheral region. After shut-in, the pore pressure gradient away from the well lessened and eventually pressure became uniform. These observations suggest that the higher pore pressure, which remained in the vicinity of the injection point, shifted to the farthest field. Shut-in pressure migration caused uniform pore pressure distribution at the edge of the seismic zone. Shut-in pressure destabilized a large part of the fault located at the edge of the seismic cloud, resulting in the shear slip of a large section of the fault. Meanwhile, during stimulation, only some parts of the fault entered the critical state because of the pressure gradient. The resulting shear slip on that specific part causes moderate magnitude events at most.

  3. Compaction-induced elevated pore pressure and creep pulsing in California faults

    NASA Astrophysics Data System (ADS)

    Khoshmanesh, M.; Shirzaei, M.

    2016-12-01

    The creeping segment of San Andreas Fault (CSAF) is recognized as a weak fault, namely, cannot sustain large earthquake stress drops. Moreover, variable creep rate constrained using kinematic models of geodetic and seismic data implies that the fault frictional strength is both spatially and temporally variable. Intrinsic low friction of fault zone material and locally elevated pore pressure due to ascend of mantle-derived fluid are proposed as possible justifications for CSAF weakness. However, lack of plausible explanation for creep pulsing observed at seismogenic zone in both hypotheses, calls for rethinking of the underlying mechanisms and processes governing the CSAF behavior. Here we provide evidence for the role of pore pressure variation in changing the fault frictional strength, not primarily due to mantle fluids. Using a rate- and state-dependent friction model, we estimate fault frictional properties between 2003 and 2011, and link their apparent temporal variations to undulation of effective normal stress. Since there is no evidence that tectonic stressing rate varies during this study period, we conclude that the variation of effective normal stress is a result of pore pressure change in the fault zone. We show that temporally variable pore pressure and its inferred spatial heterogeneity correlate perfectly with the variation of surface creep rate obtained using InSAR observations. Furthermore, our analysis of microseismicity suggests that the temporal variation of Gutenberg-Richter b-value and released seismic moment has respectively positive and negative correlation with the pore pressure variations. Our results highlight the role of 3D seal-bounded compartments formed through the compaction of intergranular pore spaces, leading to spatially heterogeneous elevated pore pressure and initiation of accelerated creep events. Frictional dilation due to creep acceleration, on the other hand, causes redistribution and reduction of the pore pressure

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

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

    Poroelastic theory states that when a porous aquifer is under complete undrained conditions, i.e. a porous medium is compressed or extended without allowing fluid to flow, the applied stress is always borne by pore fluid and skeletal framework of the rock. Thus the pore pressure must be a direct sensor of the crustal stress change. However, this has never been clearly observed, because the pore pressure of aquifer would often measure through the water level in an open well under the assumption that it is in equilibrium with the pore pressure. In open wells, changes in pore pressure must be accompanied with flow into or out of the wall, which definitely prevents the well from being a gage of pore pressure in an aquifer. Limited hydraulic communication between well and aquifer causes the delay and attenuation in frequency response. And the dimension and geometry of well also greatly affect the performance. We could overcome these shortcomings by stopping up a flowing well bore and directly measuring the fluid (pore) pressure, p within it, and we found that the fluid pressure of such closed wells show the first-order response from tidal to seismic frequencies. A site-investigation tunnel was excavated at 350 m depth from the gallery of the Kamioka mine across the Mozumi fault, a part of the Atotsugawa fault system in central Japan. We have monitored the fluid pressure using pressures gage (full scale is 2.069 MPa, resolution is 16 bit, and sampling rate is 20 Hz) at two well bores on both sides of the fault; C-well, the diameter is 140 mm, the length is 600 m, the inclination is -70°, and the flowing rate is 375 l/min; A-well, the diameter is 76 mm, the length is 15 m, the inclination is -5°, and the flowing rate is 25 l/min. We have also observed the barometric pressure, b in the tunnel. On stopping up a well bore, the pore pressure have gradually built up and attained the stable state in a half year (C-well; 1.43MPa, A-well; 0.99MPa). Tiny but clear fluctuations

  5. Method for determining pore pressure and horizontal effective stress from overburden and effective vertical stresses

    SciTech Connect

    Holbrook, P.; Robertson, H.A.; Hauck, M.L.

    1990-01-01

    This patent describes a method for determining pore pressure in an in-situ subsurface formation. It comprises: causing a well logging tool to traverse an earth borehole between the earth's surface and the subsurface formation; determining the total overburden stress resulting from the integrated weight of material overlying the subsurface formation between the earth's surface and the subsurface formation. The overburden stress determining step being a function of the density of the solid rock portion and of the density of the fluid filling the pore spaces in the the overlying materials as measured, at least in part, by the well logging tool; determining the vertical effective stress in the subsurface formation from porosity logs. The porosity logs being generated by the well logging tool as the tool traverses the earth borehole through the subsurface formation; and generating a pore pressure log indicative of the difference between the overburden stress and the vertical effective stress.

  6. Pore pressure in a wind-swept rippled bed below the suspension threshold

    NASA Astrophysics Data System (ADS)

    Musa, R. A.; Takarrouht, S.; Louge, M. Y.; Xu, J.; Berberich, M. E.

    2014-12-01

    Toward elucidating how a wavy porous sand bed perturbs a turbulent flow above its surface, we record pressure within a permeable material resembling the region just below desert ripples, contrasting these delicate measurements with earlier studies on similar impermeable surfaces. We run separate tests in a wind tunnel on two sinusoidal porous ripples with aspect ratio of half crest-to-trough amplitude to wavelength of 3% and 6%. For the smaller ratio, pore pressure is a function of streamwise distance with a single delayed harmonic decaying exponentially with depth and proportional to wind speed squared. The resulting pressure on the porous surface is nearly identical to that on a similar impermeable wave. Pore pressure variations at the larger aspect ratio are greater and more complicated. Consistent with the regime map of Kuzan et al., the flow separates, creating a depression at crests. Unlike flows on impermeable waves, the porous rippled bed diffuses the depression upstream, reduces surface pressure gradients, and gives rise to a slip velocity, thus affecting the turbulent boundary layer. Pressure gradients within the porous material also generate body forces rising with wind speed squared and ripple aspect ratio, partially counteracting gravity around crests, thereby facilitating the onset of erosion, particularly on ripples of high aspect ratio armored with large surface grains. By establishing how pore pressure gradients scale with ripple aspect ratio and wind speed, our measurements quantify the internal seepage flow that draws dust and humidity beneath the porous surface.

  7. Effect of pore and confining pressure on the supercritical CO2 permeability of sandstone: Implications for the effective pressure law

    NASA Astrophysics Data System (ADS)

    Choi, C. S.; Cheon, D. S.; Song, J. J.

    2017-08-01

    The liquid permeability of rock with distilled water or brine is different from that obtained using gas by variation in the confining pressure Pc and pore pressure Pp. In this study, as part of the research on CO2 geological storage, the permeability of sandstone was measured using supercritical CO2, and the effect of Pc and Pp on this permeability was analyzed. For applying the effective pressure law to the analysis, an effective pressure coefficient for permeability was derived experimentally. In order to utilize supercritical CO2, a non-Darcy flow test with a high flow rate was conducted, and the permeability was estimated through the Forchheimer equation. We contoured iso-permeability lines with confining and pore pressure conditions that have identical permeability, and the effective pressure coefficient, χ, was derived from the gradient of the lines following the definition of the effective pressure law. It was identified that the coefficient could be different depending on the pressure conditions. To clarify the variation of the coefficient, we derived the coefficient of χ(Pc, Pp) as a function of pore and confining pressure. The coefficient increased nonlinearly as the difference between Pc and Pp decreased, with a maximum of 1.36 being observed. The correlation between the effective pressure and the permeability were examined by applying empirical models. It was determined that the power law model was appropriate to estimate the change in supercritical CO2 permeability. Especially, it was deduced that the effective pressure with the derived coefficient would be more valid than the Terzaghi effective pressure.

  8. Temporal pore pressure induced stress changes during injection and depletion

    NASA Astrophysics Data System (ADS)

    Müller, Birgit; Heidbach, Oliver; Schilling, Frank; Fuchs, Karl; Röckel, Thomas

    2016-04-01

    Induced seismicity is observed during injection of fluids in oil, gas or geothermal wells as a rather immediate response close to the injection wells due to the often high-rate pressurization. It was recognized even earlier in connection with more moderate rate injection of fluid waste on a longer time frame but higher induced event magnitudes. Today, injection-related induced seismicity significantly increased the number of events with M>3 in the Mid U.S. However, induced seismicity is also observed during production of fluids and gas, even years after the onset of production. E.g. in the Groningen gas field production was required to be reduced due to the increase in felt and damaging seismicity after more than 50 years of exploitation of that field. Thus, injection and production induced seismicity can cause severe impact in terms of hazard but also on economic measures. In order to understand the different onset times of induced seismicity we built a generic model to quantify the role of poro-elasticity processes with special emphasis on the factors time, regional crustal stress conditions and fault parameters for three case studies (injection into a low permeable crystalline rock, hydrothermal circulation and production of fluids). With this approach we consider the spatial and temporal variation of reservoir stress paths, the "early" injection-related induced events during stimulation and the "late" production induced ones. Furthermore, in dependence of the undisturbed in situ stress field conditions the stress tensor can change significantly due to injection and long-term production with changes of the tectonic stress regime in which previously not critically stressed faults could turn to be optimally oriented for fault reactivation.

  9. A Sequential Dynamic Bayesian Network for Pore Pressure Prediction and Quantification of Uncertainty.

    NASA Astrophysics Data System (ADS)

    Oughton, R. H.; Wooff, D. A.; Hobbs, R. W.; Swarbrick, R. E.

    2014-12-01

    Pore pressure prediction is vital when drilling a well, as unexpected overpressure can cause drilling challenges and uncontrolled hydrocarbon leakage. One cause of overpressure is when pore fluid is trapped during burial and takes on part of the lithostatic load. Predictions often use porosity-based techniques, such as the Eaton Ratio method and equivalent depth method. These rely on an idealised compaction trend and use a single wireline log as a proxy for porosity. Such methods do not account for the many sources of uncertainty, or for the multivariate nature of the system. We propose a sequential dynamic Bayesian network (SDBN) as a solution to these issues. The SDBN models the quantities in the system (such as pressures, porosity, lithology, wireline logs, fluid properties and so on) using conditional probability distributions to capture their joint behaviour. A compaction model is central to the SDBN, relating porosity to vertical effective stress, with uncertainty in the relationship, so that the logic is similar to that of the equivalent depth method. The probability distribution for porosity depends on VES and lithology, with much more uncertainty in sandstone-like rocks than in shales to reflect a general lack of understanding of sandstone compaction. The distributions of the wireline logs depend on porosity and lithology, along with other quantities, and so when they are observed the SDBN learns about porosity and lithology and in turn VES and pore pressure, using Bayes theorem. The probability distribution for each quantity in the SDBN is updated in light of any data, so that rather than giving a single-valued prediction for pore pressure, the SDBN gives a prediction with uncertainty that takes into account the whole system, knowledge and data. The dynamic nature of the SDBN enables it to use the bulk density to calculate total vertical stress, and to account for the dissipation of pore pressure. The vertical correlation in the SDBN means it is suited to

  10. Elastic response of mesoporous silicon to capillary pressures in the pores

    NASA Astrophysics Data System (ADS)

    Gor, Gennady Y.; Bertinetti, Luca; Bernstein, Noam; Hofmann, Tommy; Fratzl, Peter; Huber, Patrick

    2015-06-01

    We study water adsorption-induced deformation of a monolithic, mesoporous silicon membrane traversed by independent channels of ˜8 nm diameter. We focus on the elastic constant associated with the Laplace pressure-induced deformation of the membrane upon capillary condensation, i.e., the pore-load modulus. We perform finite-element method (FEM) simulations of the adsorption-induced deformation of hexagonal and square lattices of cylindrical pores representing the membrane. We find that the pore-load modulus weakly depends on the geometrical arrangement of pores, and can be expressed as a function of porosity. We propose an analytical model which relates the pore-load modulus to the porosity and to the elastic properties of bulk silicon (Young's modulus and Poisson's ratio), and provides an excellent agreement with FEM results. We find good agreement between our experimental data and the predictions of the analytical model, with the Young's modulus of the pore walls slightly lower than the bulk value. This model is applicable to a large class of materials with morphologies similar to mesoporous silicon. Moreover, our findings suggest that liquid condensation experiments allow one to elegantly access the elastic constants of a mesoporous medium.

  11. Pore-water pressure events during the in situ heat transfer experiment simulation: Piezometer probe technology

    SciTech Connect

    Bennett, R.H.; Burns, J.T.; Li, H.; Percival, C.M.; Lipkin, J.

    1987-01-01

    Single sensor piezometer probes, 8mm in diameter were developed and tested for deep-ocean geotechnical investigations in support of the Subseabed Disposal Program. Two probes were tested in a hyperbaric chamber pressurized to 55 MPa (8000 psi) during a scaled (0.28: 1) simulation experiment conducted at the David Taylor Naval Ship Research and Development Center (DTNSRDC) in Annapolis, Md. Testing was performed for 30 days with the probes inserted in reconstituted illitic marine sediment. Small differential pore-water pressures were generated in response to both mechanically and thermally generated forcing functions. The piezometers sensed very small (approximately 1.7 kPa (0.25 psi)) pore water pressure events during the process of carrying out other experimental objectives. The pressure sensors exhibited excellent sensitivity and stability during other deep-ocean simulated laboratory pressure tests for periods of up to 750 hours. In addition to the measurements of ambient and dynamic pore pressure response to environmental forces, the piezometer test data can be used to derive the in situ undrained shear strengths and permeabilities of seabed sediments. The piezometer probe technology is providing a quantitative means of assessing important geotechnical parameters of fine-grained seabed deposits. 22 refs., 28 figs., 10 tabs.

  12. Influence of pore pressure on the successive failures of intact slopes

    NASA Astrophysics Data System (ADS)

    Voulgari, Chrysoula; Utili, Stefano

    2016-04-01

    The presence of water can significantly change the stability of a slope and as a result the evolution of a slope in time. In this paper the influence of pore water pressure on the morphological evolution of natural cliffs subject to progressive retreat is investigated. The upper bound theorem of limit analysis is employed to evaluate the stability number and the failure mechanism of successive failures of uniform c, φ slopes with the presence of water. This model extends the existing analytical framework on the evolution of slopes subjected to weathering by accounting for the presence of water. Pore-water pressure is considered in the model by using the coefficient ru, a description of the pore-water pressure distribution that is approximate, but is commonly used in slope stability analyses. To account for the influence of the pore pressure, the work of pore-water pressure on the deformation of the soil along the failure surface had to be included in the model leading to modified analytical expressions of the energy balance equation (the balance between external work and dissipated energy) and as a consequence, of the function whose minimum provides the solution in terms of failure mechanisms and associated values of soil strength. With this model it is possible to relate the evolution of natural slopes with the presence of water by a sequence of rotational sliding block failures to the degradation of material strength properties. Computations were carried out for a wide range of parameters (friction angle φ and initial slope inclination β) and a set of normalized solutions is presented for different values of ru coefficient.

  13. High-pressure replica technique for in vitro imaging of pore morphologies in teeth.

    PubMed

    Uchtmann, H; Wilkie, D

    1997-11-01

    The presence of a natural pore morphology is an essential factor in chemical and mechanical stability of teeth. Common histological methods give only an insufficient picture of the three-dimensional pore distribution in sound or carious teeth. This paper describes a new technique to obtain complete images of the pore structure in teeth or other biological hard tissues. Whole extracted human teeth from orthodontic therapy are mechanically cleaned and organic remnants removed chemically. After being (partly) dried, the teeth are penetrated by a freshly prepared and colored (rhodamine B dye) two-component epoxy resin. The resin is pressed into the pores and cavities of the teeth with pressures of up to 2000 bar in a high-pressure vessel by means of a manually driven piston screw pump for pressure generation. The resin fills all hollow spaces of the tooth down to sizes below 0.1 micron. The pulp and the root canals are cast in massive forms of the hardened epoxy resin, giving an exact replica of the natural structure. The penetrated samples in the form of whole, intact teeth are investigated microscopically so that the pore morphology of the tooth surface, including carious defects, can be examined. The structure of the pores extending into the interior of the tooth can be made visible by dissolution of the hard tissue--for example, in acid solutions. Micro-cavities filled with the resin are observed in thin, ground, and polished cross- and longitudinal sections cut from the teeth. The colored resin induces a high contrast to the dental apatite material. In fluorescence microscopy, only the resin structures are visible.

  14. The representativeness of pore water samples collected from the unsaturated zone using pressure-vacuum lysimeters

    USGS Publications Warehouse

    Peters, C.A.; Healy, R.W.

    1988-01-01

    Studies have indicated that the chemistry of water samples may be altered by the collection technique, creating concern about the representativeness of the pore water samples obtained. A study using soil water pressure-vacuum lysimeters in outwash sand and glacial till deposits demonstrates that for non-dilute-solution samples the effect of pH of sampling with lysimeters is minimal, and that measured major cation and anion concentrations are representative of the natural pore water; trace-metal concentrations can be significantly altered by collection procedures at low concentrations. -from Authors

  15. Characterization of pores in high pressure die cast aluminum using active thermography and computed tomography

    NASA Astrophysics Data System (ADS)

    Maierhofer, Christiane; Myrach, Philipp; Röllig, Mathias; Jonietz, Florian; Illerhaus, Bernhard; Meinel, Dietmar; Richter, Uwe; Miksche, Ronald

    2016-02-01

    Larger high pressure die castings (HPDC) and decreasing wall thicknesses are raising the issue of casting defects like pores in aluminum structures. Properties of components are often strongly influenced by inner porosity. As these products are being established more and more in lightweight construction (e.g. automotive and other transport areas), non-destructive testing methods, which can be applied fast and on-site, are required for quality assurance. In this contribution, the application of active thermography for the direct detection of larger pores is demonstrated. The analysis of limits and accuracy of the method are completed by numerical simulation and the method is validated using computed tomography.

  16. Landslide stability: Role of rainfall-induced, laterally propagating, pore-pressure waves

    USGS Publications Warehouse

    Priest, G.R.; Schulz, W.H.; Ellis, W.L.; Allan, J.A.; Niem, A.R.; Niem, W.A.

    2011-01-01

    The Johnson Creek Landslide is a translational slide in seaward-dipping Miocene siltstone and sandstone (Astoria Formation) and an overlying Quaternary marine terrace deposit. The basal slide plane slopes sub-parallel to the dip of the Miocene rocks, except beneath the back-tilted toe block, where it slopes inland. Rainfall events raise pore-water pressure in the basal shear zone in the form of pulses of water pressure traveling laterally from the headwall graben down the axis of the slide at rates of 1-6 m/hr. Infiltration of meteoric water and vertical pressure transmission through the unsaturated zone has been measured at ~50 mm/hr. Infiltration and vertical pressure transmission were too slow to directly raise head at the basal shear zone prior to landslide movement. Only at the headwall graben was the saturated zone shallow enough for rainfall events to trigger lateral pulses of water pressure through the saturated zone. When pressure levels in the basal shear zone exceeded thresholds defined in this paper, the slide began slow, creeping movement as an intact block. As pressures exceeded thresholds for movement in more of the slide mass, movement accelerated, and differential displacement between internal slide blocks became more pronounced. Rainfall-induced pore-pressure waves are probably a common landslide trigger wherever effective hydraulic conductivity is high and the saturated zone is located near the surface in some part of a slide. An ancillary finding is apparently greater accuracy of grouted piezometers relative to those in sand packs for measurement of pore pressures at the installed depth.

  17. Deformation of a Volcanic Edifice by Pore Pressurization: An Analog Approach

    NASA Astrophysics Data System (ADS)

    Hyman, D.; Bursik, M. I.

    2015-12-01

    Volcanic flank destabilization, preceded by pressurization-induced surface deformation or weakening, presents a significant hazard at stratovolcanoes with ample supply of magmatic volatiles or preexisting hydrothermal systems as in Bezymianny- and Bandai-type eruptions, respectively. Deformation is also an important sign of the nature of unrest at large calderas such as Long Valley, USA. Previous studies of volcanic inflation have focused primarily on the role of ascending magma. Relatively few studies have centered on surface deformation caused by pressurization from other volcanic fluids, including exsolved volatiles and pressurized hydrothermal systems. Most investigations of pore-pressurization have focused on numerical modelling of pore pressure transients. In analog experiments presented here, pore-filling fluids are injected into the base of a damp sand medium without exceeding dike propagating pressures, simulating the pressurization and bulk-permeable flow of volatile fluids through volcanic systems. The experiments examine surface deformation from a range of source depths and pressures as well as edifice geometries. 3D imaging is possible through use of the Microsoft® Kinect™ sensor, which allows for the generation of high-resolution, high frame rate, lab-scale Digital Elevation Models (DEMs). After initial processing to increase signal-to-noise ratio, surface deformation is measured using the DEM time-series generated by the Kinect™. Analysis of preliminary experiments suggests that inflation is possible up to approx. 10 % of pressure source depth. We also show that the Kinect™ sensor is useful in analog volcanological studies, an environment to which it is well-suited.

  18. Effects of Non-linear Terms and Fault Width on Pore Fluid Pressurization

    NASA Astrophysics Data System (ADS)

    Vredevoogd, M. A.; Oglesby, D. D.; Park, S. K.

    2007-12-01

    Faults generate heat due to friction while slipping in earthquakes. If there are pore fluids along the fault, they will be heated and expand. The pore fluids will have little effect on faults in high permeability settings, as they quickly escape. In a low permeability setting, the expanding pore fluids are not able to escape quickly, and thermal expansion of the fluids will increase the fluid pressure, lowering the effective normal stress (and thus frictional stress) along the fault. To investigate this process, we solve the non-linear equations presented in Mase and Smith (1985). These equations involve several non-linear terms that make it necessary to solve the equations iteratively. We have previously shown some results of this methodology for various permeability structures and slip rates. Here we focus on the importance of individual terms in the equations by running models with individual terms neglected. Among our results, we find that conduction significantly affects the temperature and pressure, while advection has a negligible effect on the solution. The implications may be important for researchers constructing simplified models of the pore fluid pressurization process. We also look at the effect of fault width (the width of the area that is shearing and producing heat). In particular, we are interested in the effects of the fault width on the maximum temperature reached, as well as the total amount of frictional heat generated. While a wider fault will tend to have a lower peak temperature because of the distributed slip, it can also result in a larger overall heat generation, because the average temperature over the fault width can be higher than for a narrow fault with a higher, but narrower temperature peak. In contrast, while the narrow faults initially have the highest pressures, the wider faults eventually surpass them both in maximum pressure, and in the amount of overall pressurization.

  19. Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

    NASA Astrophysics Data System (ADS)

    Springer, H. K.; Tarver, C. M.; Bastea, S.

    2017-01-01

    The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase

  20. Thermodynamically consistent modeling of granular-fluid mixtures incorporating pore pressure evolution and hypoplastic behavior

    NASA Astrophysics Data System (ADS)

    Heß, Julian; Wang, Yongqi; Hutter, Kolumban

    2017-01-01

    This paper presents a new, thermodynamically consistent model for granular-fluid mixtures, derived with the entropy principle of Müller and Liu. Including a pressure diffusion equation combined with the concept of extra pore pressure, and hypoplastic material behavior, thermodynamic restrictions are imposed on the constitutive quantities. The model is applied to a granular-fluid flow, using a closing assumption in conjunction with the fluid pressure. While the focal point of the work is the conceptional part, i.e. the thermodynamic consistent modeling, numerical simulations with physically reasonable results for simple shear flow are also carried out.

  1. High-velocity frictional experiments on dolerite and quartzite under controlled pore pressure

    NASA Astrophysics Data System (ADS)

    Togo, T.; Shimamoto, T.; Ma, S.

    2013-12-01

    High-velocity friction experiments on rocks with or without gouge have been conducted mostly under dry conditions and demonstrated dramatic weakening of faults at high velocities (e.g., Di Toro et al., 2011, Nature). Recent experiments under wet conditions (e.g., Ujiie and Tsutsumi, 2010, GRL; Faulkner et al., 2011, GRL) revealed very different behaviors from those of dry faults, but those experiments were done under drained conditions. Experiments with controlled pore pressure Pp are definitely needed to determine mechanical properties of faults under fluid-rich environments such as those in subduction zones. Thus we have developed a pressure vessel that can be attached to our rotary-shear low to high-velocity friction apparatus (Marui Co Ltd., MIS-233-1-76). With a current specimen holder, friction experiments can be done on hollow-cylindrical specimens of 15 and 40 mm in inner and outer diameters, respectively, at controlled Pp to 35 MPa, at effective normal stresses of 3~9 MPa, and at slip rates of 60 mm/year to 2 m/s. An effective normal stress can be applied with a 100 kN hydraulic actuator. We report an outline of the experimental system and preliminary high-velocity experiments on Shanxi dolerite and a quartzite from China that are composed of pyroxene and plagioclase and of almost pure quartz, respectively. High-velocity friction experiments were performed on hollow-cylindrical specimens of Shanxi dolerite at effective normal stresses of 0.13~1.07 MPa and at slip rates of 1, 10, 100 and 1000 mm/sec. All experiments were conducted first with the nitrogen gas filling the pressure vessel (dry tests) and then with a controlled pore-water pressure (wet tests). In the dry tests an axial force was kept at 1 kN and the nitrogen gas pressure was increased in steps to 5 MPa to change an effective normal stress. In the wet tests the specimens were soaked in distilled water in the vessel and Pp was applied by nitrogen gas in a similar manner as in the dry tests

  2. Using core properties and seismic reflectivity to estimate pore pressure in an active decollement fault

    SciTech Connect

    Tobin, H.J.; Moore, J.C.

    1996-12-31

    In the decollement zone of the Barbados accretionary prism, a 3-D seismic image exhibits patchy high-amplitude negative polarity reflections, which have been attributed to large overpressures confined to the fault zone. We collected laboratory P-wave velocity and porosity vs. pore pressure data, using core samples from and adjacent to the decollement zone at ODP Site 948. Logs constrain density and velocity through the decollement zone at Site 948. We use these data to calibrate the reflectivity of the fault zone to pore pressure through waveform and amplitude models of the fault plane reflections. Modeling of the positive polarity Site 948 reflection indicates that it can be explained by a lithologic boundary coincident with the decollement, without anomalous fault properties. By contrast, the dominantly-negative polarity waveform of the reflection {approx}2 km arcward (beneath Site 947) is best modeled by inserting a 16-19 m thick zone of extremely low impedance into the Site 948 impedance structure, with a gradational return to {open_quotes}normal{close_quotes} impedance just above the positive boundary. Relative amplitudes in this reflection indicate a larger impedance contrast than can be accounted for at sub-lithostatic fluid pressure, based on the core properties data. We conclude that lithostatic pore pressure with attendant hydraulic dilation of the fault zone is required to generate the negative-polarity reflections. Mapping of these reflections thus delineates zones of elevated fluid content and zero effective stress in the fault zone.

  3. Using core properties and seismic reflectivity to estimate pore pressure in an active decollement fault

    SciTech Connect

    Tobin, H.J. ); Moore, J.C. )

    1996-01-01

    In the decollement zone of the Barbados accretionary prism, a 3-D seismic image exhibits patchy high-amplitude negative polarity reflections, which have been attributed to large overpressures confined to the fault zone. We collected laboratory P-wave velocity and porosity vs. pore pressure data, using core samples from and adjacent to the decollement zone at ODP Site 948. Logs constrain density and velocity through the decollement zone at Site 948. We use these data to calibrate the reflectivity of the fault zone to pore pressure through waveform and amplitude models of the fault plane reflections. Modeling of the positive polarity Site 948 reflection indicates that it can be explained by a lithologic boundary coincident with the decollement, without anomalous fault properties. By contrast, the dominantly-negative polarity waveform of the reflection [approx]2 km arcward (beneath Site 947) is best modeled by inserting a 16-19 m thick zone of extremely low impedance into the Site 948 impedance structure, with a gradational return to [open quotes]normal[close quotes] impedance just above the positive boundary. Relative amplitudes in this reflection indicate a larger impedance contrast than can be accounted for at sub-lithostatic fluid pressure, based on the core properties data. We conclude that lithostatic pore pressure with attendant hydraulic dilation of the fault zone is required to generate the negative-polarity reflections. Mapping of these reflections thus delineates zones of elevated fluid content and zero effective stress in the fault zone.

  4. Assessment of pore pressures and specific storage within sedimentary strata overlying underground mines

    NASA Astrophysics Data System (ADS)

    Timms, W.; David, K.; Barbour, L. S.

    2016-12-01

    Realistic values of specific storage (Ss) for groundwater systems are important to determine the spatial extent and timing of c pore pressure changes when the groundwater system is stressed. However, numerical groundwater models of underground excavations typically assume constant literature values of Ss. One part of our research program utilised high frequency pore pressure data to evaluate variability and changes in Ss within sedimentary strata overlying a longwall coal mine. Pore pressure data from a vertical series of 6 vibrating wire piezometers (50 to 278 m depth) recording at hourly intervals were compared with barometric pressure data over a period of several years, including data before and during mining. The site was located near the centre of a longwall panel that extracted 3 m of coal at a depth of 330 m. The data was processed to calculate loading efficiency and Ss values by multi-method analyses of barometric and earth tide responses. In situ Ss results varied over one to two orders of magnitude and indicated that Ss changed before and after excavation of underlying coal seams. The vertical leakage of groundwater within the constrained zone ( 10 to 150 m depth) was found to be limited, although some degree of vertical hydraulic connectivity was observed. Depressurization was evident in the fractured zone directly overlying the coal seam, and Ss changes at 250 m depth indicated this confined aquifer may have become unconfined. Our results demonstrate that high frequency pore pressure data can provide realistic Ss values. In situ Ss values were an order of magnitude lower than Ss measured by geomechnical tests of cores, and were significantly different to textbook values set in most local groundwater models. The timing and extent of groundwater level drawdown predicted by models may therefore be underestimated. We have shown, for the first time, that variability of Ss can be significant, and that these changes can provide important insights into how

  5. Deterministic estimate of hypocentral pore fluid pressure of the M5.8 Pawnee, Oklahoma earthquake: Lower pre-injection pressure requires lower resultant pressure for slip

    NASA Astrophysics Data System (ADS)

    Levandowski, W. B.; Walsh, F. R. R.; Yeck, W.

    2016-12-01

    Quantifying the increase in pore-fluid pressure necessary to cause slip on specific fault planes can provide actionable information for stakeholders to potentially mitigate hazard. Although the M5.8 Pawnee earthquake occurred on a previously unmapped fault, we can retrospectively estimate the pore-pressure perturbation responsible for this event. We first estimate the normalized local stress tensor by inverting focal mechanisms surrounding the Pawnee Fault. Faults are generally well oriented for slip, with instabilities averaging 96% of maximum. Next, with an estimate of the weight of local overburden we solve for the pore pressure needed at the hypocenters. Specific to the Pawnee fault, we find that hypocentral pressure 43-104% of hydrostatic (accounting for uncertainties in all relevant parameters) would have been sufficient to cause slip. The dominant source of uncertainty is the pressure on the fault prior to fluid injection. Importantly, we find that lower pre-injection pressure requires lower resultant pressure to cause slip, decreasing from a regional average of 30% above hydrostatic pressure if the hypocenters begin at hydrostatic pressure to 6% above hydrostatic pressure with no pre-injection fluid. This finding suggests that underpressured regions such as northern Oklahoma are predisposed to injection-induced earthquakes. Although retrospective and forensic, similar analyses of other potentially induced events and comparisons to natural earthquakes will provide insight into the relative importance of fault orientation, the magnitude of the local stress field, and fluid-pressure migration in intraplate seismicity.

  6. Pore-by-pore capillary pressure measurements using X-ray microtomography at reservoir conditions: Curvature, snap-off, and remobilization of residual CO2

    NASA Astrophysics Data System (ADS)

    Andrew, Matthew; Bijeljic, Branko; Blunt, Martin J.

    2014-11-01

    X-ray microtomography was used to image the shape and size of residual ganglia of supercritical CO2 at resolutions of 3.5 and 2 μm and at representative subsurface conditions of temperature and pressure. The capillary pressure for each ganglion was found by measuring the curvature of the CO2-brine interface, while the pore structure was parameterized using distance maps of the pore space. The formation of the residual clusters by snap-off was examined by comparing the ganglion capillary pressure to local pore topography. The capillary pressure was found to be inversely proportional to the radius of the largest restriction (throat) surrounding the ganglion, which validates the imbibition mechanisms used in pore-network modeling. The potential mobilization of residual ganglia was assessed using a reformulation of both the capillary (Ncmacro) and Bond numbers (Nbmacro), rigorously based on a balance of pore-scale forces, with the majority of ganglia remobilized at Ncmacro around 1. Buoyancy forces were found to be small in this system (Nbmacro << 1), meaning the gravitational remobilization of CO2 after residual trapping would be extremely difficult.

  7. Pore-scale capillary pressure analysis using multi-scale X-ray micromotography

    NASA Astrophysics Data System (ADS)

    Garing, Charlotte; de Chalendar, Jacques A.; Voltolini, Marco; Ajo-Franklin, Jonathan B.; Benson, Sally M.

    2017-06-01

    A multi-scale synchrotron-based X-ray microtomographic dataset of residually trapped air after gravity-driven brine imbibition was acquired for three samples with differing pore topologies and morphologies; image volumes were reconstructed with voxel sizes from 4.44 μm down to 0.64 μm. Capillary pressure distributions among the population of trapped ganglia were investigated by calculating interfacial curvature in order to assess the potential for remobilization of residually-trapped non-wetting ganglia due to differences in capillary pressure presented by neighbor ganglia. For each sample, sintered glass beads, Boise sandstone and Fontainebleau sandstone, sub-volumes with different voxel sizes were analyzed to quantify air/brine interfaces and interfacial curvatures and investigate the effect of image resolution on both fluid phase identification and curvature estimates. Results show that the method developed for interfacial curvature estimation leads to reliable capillary pressure estimates for gas ganglia. Higher resolution images increase confidence in curvature calculations, especially for the sandstone samples that display smaller gas-brine interfaces which are then represented by a higher number of voxels when imaged with a micron or sub-micron voxels size. The analysis of sub-volumes from the Boise and Fontainebleau dataset highlights the presence of a residually-trapped gas phase consisting of ganglia located in one or few pores and presenting significantly different capillary pressures, especially in the case of Fontainebleau sandstone. As a result, Ostwald ripening could occur, leading to gas transfer from ganglia with higher capillary pressure to surrounding ganglia with lower capillary pressures. More generally, at the pore-scale, most gas ganglia do present similar capillary pressures and Ostwald ripening would then not represent a major mechanism for residually-trapped gas transfer and remobilization.

  8. Simulated Seismic Load Tests on Dam Core Material to Scrutinize Pore Water Pressure Development

    NASA Astrophysics Data System (ADS)

    Umar Farooq, Qazi; Uchimura, Taro

    2010-05-01

    Dam Core is the back bone of the large earthen dam and primarily constructed with fine grained soils. In this research Cyclic tri-axial tests are used to simulate the effect of different earthquake intensities on medium to high confined Fujinomori clay (replicated dam core material). Seismic load intensity is reproduced in the laboratory by applying different cyclic stress amplitudes, while the numbers of cycles (N) were kept constant. Both isotropic and anisotropic conditions are included in the test plan. Key discussions are distresses generated by seismic loading such as pore water pressure (PWP), deformations, possibility of micro cracking, and effective strength reduction. With increase in cyclic stress amplitude, exponential increases in pore pressure (PWP), sudden decrease in mean effective principal stress (P') which ultimately increases overall instability in dam core, large deformations, and generation of micro / macro cracking are primary conclusions.

  9. Determining Pore Pressures Along a Slip Surface Within a Saturated Elastic-Plastic Porous Medium

    NASA Astrophysics Data System (ADS)

    Viesca, R. C.; Rice, J. R.; Dunham, E. M.

    2008-12-01

    Here we consider shear rupture along a slip surface in a fluid-saturated elastic-plastic porous medium, like in landslide and earthquake modeling, and assume that there are different poro-elasto-plastic response properties on the two sides of the slip surface. This different response may be because the fault bordering materials are dissimilar, or just because one side is actively yielding and the other is not, or is yielding but in a different mode. In effect, we are representing a core about a slip surface that divides two similar or contrasting materials. This representation is especially relevant in earthquake rupture dynamics. Studies of mature fault zones have noted a trend of fractured host rock extending 10--100m from the fault, with an ultracataclastic core ~100mm about or to one side of the principal slip surface (e.g., Chester and Chester, Tectonophys, 1998; Chester et al., Columbia Univ Pr, 2004). Furthermore, there is likely to exist a material contrast that may come from accumulating km of slip and a bias in accumulated damage. The local pore pressure at the slip surface influences the rupture dynamics because, through the effective stress concept, it controls the local shear strength along the fault, a feature neglected as a simplification in our preliminary poro-elasto-plastic modeling of dynamic rupture (Viesca et al., JGR, 2008). To determine pore pressures at the slip surface under locally elastic-plastic response, we must consider pore pressure discontinuities about that surface that arise in an undrained treatment of off-fault material and their amelioration within resulting thin diffusive boundary layers, such that pore pressure and fluid mass flux in the normal direction are continuous at the slip surface. Our approach builds on previous work considering the effect of contrasts in poroelastic properties on rupture propagation (Rudnicki and Rice, JGR, 2006; Dunham and Rice, JGR, 2008). Here we find expressions for the undrained pore pressure

  10. An experimental study on the wave-induced pore water pressure change and relative influencing factors in the silty seabed

    NASA Astrophysics Data System (ADS)

    Li, Anlong; Luo, Xiaoqiao; Lin, Lin; Ye, Qing; Le, Chunyu

    2014-12-01

    In this study, a flume experiment was designed to investigate the characteristics of wave-induced pore water pressure in the soil of a silty seabed with different clay contents, soil layer buried depths and wave heights respectively. The study showed that water waves propagating over silty seabed can induce significant change of pore water pressure, and the amplitude of pore pressure depends on depth of buried soil layer, clay content and wave height, which are considered as the three influencing factors for pore water pressure change. The pressure will attenuate according to exponential law with increase of soil layer buried depth, and the attenuation being more rapid in those soil layers with higher clay content and greater wave height. The pore pressure in silty seabed increases rapidly in the initial stage of wave action, then decreases gradually to a stable value, depending on the depth of buried soil layer, clay content and wave height. The peak value of pore pressure will increase if clay content or depth of buried soil layer decreases, or wave height increases. The analysis indicated that these soils with 5% clay content and waves with higher wave height produce instability in bed easier, and that the wave energy is mostly dissipated near the surface of soils and 5% clay content in soils can prevent pore pressure from dissipating immediately.

  11. Pressure- and heat-induced insertion of CO2 into an auxetic small-pore zeolite.

    PubMed

    Lee, Yongjae; Liu, Dan; Seoung, Donghoon; Liu, Zhenxian; Kao, Chi-Chang; Vogt, Thomas

    2011-02-16

    When the small-pore zeolite natrolite is compressed at ca. 1.5 GPa and heated to ca. 110 °C in the presence of CO(2), the unit cell volume of natrolite expands by 6.8% and ca. 12 wt % of CO(2) is contained in the expanded elliptical channels. This CO(2) insertion into natrolite is found to be reversible upon pressure release.

  12. Incorporating Undrained Pore Fuid Pressurization Into Analyses of Off-Fault Plasticity During Dynamic Rupture

    NASA Astrophysics Data System (ADS)

    Viesca, R. C.; Templeton, E. L.; Rice, J. R.

    2007-12-01

    When considering dynamic fault rupture in fluid-saturated elastic-plastic materials, it is sensible to assume locally undrained behavior everywhere except in small diffusive boundary layers along the rupture surface. To evaluate undrained pore pressure changes, we consider here not just the linear poroelastic effect expressed in terms of the Skempton coefficient B, like in our previous work [Viesca et al., AGU Fall 2006], but also include plastic dilatancy, which, when positive, induces a fluid suction. We work in the context of Mohr-Coulomb-like plasticity, but with a Drucker-Prager type model. Plastic parts of strain increments are controlled by the Terzaghi effective stress, elastic parts by the Biot stress combination. Following earlier work of Rudnicki, the incremental elastic-plastic constitutive relation for undrained deformation has precisely the same form as for drained deformation, so long as we change the drained constitutive parameters into new undrained ones under transformation rules that we present. Spontaneous slip-weakening fault rupture is analyzed using the dynamic finite element procedures with ABAQUS Explicit, and undrained elastic-plastic properties. Results are shown for plastic zones and effects on rupture propagation, and how they are influenced by such parameters as B and ratio β of dilatant to shear plastic strains, for a range of principal orientations and magnitudes (relative to yield) of the pre-stress state. The undrained approximation must fail in diffusive boundary layers along the slip surface [Rudnicki and Rice, JGR 2006; Dunham and Rice, AGU Fall 2006] because the predicted pore pressures will be discontinuous at the fault. We show how to extend the Rudnicki and Rice calculation of the actual pore pressure on the fault in terms of the undrained predictions to the two sides. However, because of difficulties thus far in representing this within the ABAQUS program, all results obtained as of the time of writing neglect effects of

  13. Estimation of upper limit of pore pressure by fault stability analysis

    NASA Astrophysics Data System (ADS)

    Chen, Zijian; Deng, Jingen; Yu, Baohua; Zhang, Yanan; Chen, Zhuo

    2016-06-01

    Generally, the pore pressure for a pre-drill well is predicted using empirical parameters, which are regressed from the drilled well's data. However, for areas with large geological differences, empirical parameters which are obtained using traditional methods may fail because intense tectonic movement would result in huge differences between the pre-drill well and drilled well. Firstly, in order to overcome this problem, the method of fault stability analysis is introduced. Analysis indicates that when abnormal overpressure exceeds a certain value, the fault ruptures and the overpressured fluid escapes, so that there is an upper limit of pore pressure (ULPP) for the stable fault. Secondly, the influences of fault angle, formation Poisson ratio and modulus of elasticity on the ULPP are discussed further. The results show that the ULPP of a fault with angle of 65.2° is the minimum, and the critical angle increases with the increase of internal friction coefficient. For reverse faults and strike faults, the influences of Poisson ratio and modulus of elasticity are small, but for normal faults these are significant. Finally, three kinds of ULPP for these different faults are proposed, respectively. The application of this method in the Xihu Sag in the East China Sea has proved that reference to ULPP can verify and correct regressed empirical parameters, so as to improve pore pressure prediction accuracy.

  14. Geomechanical modelling of induced seismicity using Coulomb stress and pore pressure changes

    NASA Astrophysics Data System (ADS)

    Zhao, B.; Shcherbakov, R.

    2016-12-01

    In recent years, there has been a dramatic increase in seismicity (earthquakes) due to anthropogenic activities related to the unconventional oil and gas exploration in the Western Canada Sedimentary Basin (WCSB). There are compelling evidences that hydraulic fracturing and wastewater injection operations play a key role in induced seismicity in the WCSB; however, their physical mechanisms are still not fully understood. Therefore, this study focuses on exploring the physical mechanisms of induced seismicity and developing a realistic geomechanical model by incorporating the past seismicity and well production data. In this work, we model the Coulomb stress changes due to past moderate (magnitude greater than 3 with known fault plane solutions) induced earthquakes and pore pressure changes due to wastewater injection in Alberta, specifically in Fox Creek and Fort St. John areas. Relationships between Coulombs stress changes, fault geometry and orientation and subsequent earthquake locations are tested. Subsurface flow due to injection well operations is studied to model the pore pressure changes in time and space, using known well production data, which include well types, well locations and water extraction and injection rates. By modelling the changes in pore pressure and Coulomb stress, we aim at constraining the time scale of occurrence of possible future earthquakes. The anticipating results can help to control the parameters of anthropogenic energy related operations such as hydraulic fracturing and wastewater injection in mitigating the risk due to induced seismicity.

  15. Elucidating the mechanical effects of pore water pressure increase on the stability of unsaturated soil slopes

    NASA Astrophysics Data System (ADS)

    Buscarnera, G.

    2012-12-01

    The increase of the pore water pressure due to rain infiltration can be a dominant component in the activation of slope failures. This paper shows an application of the theory of material stability to the triggering analysis of this important class of natural hazards. The goal is to identify the mechanisms through which the process of suction removal promotes the initiation of mechanical instabilities. The interplay between increase in pore water pressure, and failure mechanisms is investigated at material point level. In order to account for multiple failure mechanisms, the second-order work criterion is used and different stability indices are devised. The paper shows that the theory of material stability can assess the risk of shear failure and static liquefaction in both saturated and unsaturated contexts. It is shown that the combined use of an enhanced definition of second-order work for unsaturated porous media and a hydro-mechanical constitutive framework enables to retrieve bifurcation conditions for water-infiltration processes in unsaturated deposits. This finding discloses the importance of the coupling terms that incorporate the interaction between the solid skeleton and the pore fluids. As a consequence, these theoretical results suggest that some material properties that are not directly associated with the shearing resistance (e.g., the potential for wetting compaction) can play an important role in the initiation of slope failures. According to the proposed interpretation, the process of pore pressure increase can be understood as a trigger of uncontrolled strains, which at material point level are reflected by the onset of bifurcation conditions.

  16. A stick-slip movement mechanism for submarine landslides generated by elevated pore fluid pressure

    NASA Astrophysics Data System (ADS)

    Carey, Jonathan; Crutchley, Gareth; Mountjoy, Joshu; Petley, David; McSaveney, Mauri; Lyndsell, Barbara

    2017-04-01

    Despite their importance to offshore hazards, submarine landslide mechanisms and styles of failure are not well characterized when compared to terrestrial landslides. Both slow and rapid movement (strain) events have been observed in terrestrial slopes depending on the material response to elevated pore pressures. The mechanisms controlling the transition from slow movement to rapid failure, therefore, are likely to be key drivers in determining the behavior of any given submarine landslide but remain poorly understood. We use novel laboratory testing in a Dynamic Back-Pressured Shearbox to accurately replicate in-situ stresses in submarine slopes and explore strain development under changing stress conditions in a submarine landslide. Testing was conducted on gravity core samples from the Tuaheni Landslide Complex, collected from the seafloor off the east coast of North Island, New Zealand. We used both water and nitrogen gas as pore fluids, and observed similar responses in both cases, indicating that behavior is dominated by the normal effective stress state rather than pore fluid properties. Shear strain accumulation, representing landslide movement, shows a stick-slip pattern, in common with many terrestrial landslides. Our results suggest that this is due to localized generation of high pore fluid pressures as the shear stress initiates deformation (generating the observed slip phase), and then localized dissipation as the shear zone expands (generating the observed stick phase). We conclude that some submarine landslides may show similar stick-slip behavior to terrestrial landslides during periods when the effective stress is sufficiently reduced. Through this stick-slip mechanism, the landslide may be able to accumulate large shear strains without developing a phase of catastrophic movement. This indicates that, in certain conditions, long term, slow deformation of submarine landslides is a viable movement mechanism.

  17. Friction experiments of halite in brittle-ductile transition with high pore pressure

    NASA Astrophysics Data System (ADS)

    Noda, H.; Takahashi, M.; Katayama, I.

    2015-12-01

    Flow stress of rock (τ) approximately linearly depends on normal stress on a shear zone (σn) minus pore pressure (p) in a brittle regime, and insensitive to σn in a fully plastic regime where pores are isolated and filled with fluid of high pressure comparable to the mean stress, like oil drops in water. How p affects τ in the transitional regime is not fully understood, although it is a key to understanding many important geological problems such as role of fluids in deformation mechanism, stress and strength profile of the crust, seismogenic depth range, and so on. The effective normal stress σe is often given by σe = σn - α p (α: a constant around 1 in the brittle regime), and frictional resistance, by τ = f σe (f: friction coefficient). Recently, Hirth and Beeler [2015] proposed a model of the effective stress law in the transitional regime. Because of increasing ratio of real area of contact to nominal area of frictional interface, α may decrease to zero towards fully plastic regime, causing a sharper peak in the strength profile than a conventional Brace-Goetze strength profile which is sometimes referred to as "Christmas tree". We investigated this idea by means of friction experiments at high temperature and pore pressure. We used halite as an analogue material which undergoes a transition from brittle to fully plastic regime under convenient conditions [Shimamoto, 1986]. We conducted friction experiments of a pre-cut sliding interface filled with halite gouge with gas-medium triaxial apparatus in Hiroshima University, at 150 MPa confining pressure, from room temperature to 210 °C, and from atmospheric pressure to more than 100 MPa fluid (argon gas) pressure in a reservoir. Our preliminary result shows that the sharp peak in the flow stress is probably absent. A phenomenological smooth connection proposed by Shimamoto and Noda [2014] based on friction experiments without a jacket (i.e. atmospheric pore pressure) may work in explaining the

  18. A New Mechanism for Pore Pressure Changes Induced by Distant Earthquakes

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.

    2001-12-01

    Observations during the Mw=7.3 1992 Landers earthquake, Mw=7.4 Izmit earthquake and Mw=7.2 Hector Mine earthquake suggest that seismicity is triggered hundreds of kilometers from a mainshock epicenter. This puzzling phenomenon is not explained by traditional elastic models of seismic stresses. The fact that the triggered sites are often geothermal or magmatic suggests that fluids may be an important part of the triggering process. Rapid changes in pore pressure either reduce the effective stress on faults locally or prompt hydrofracturing to initiate local earthquakes. The challenge is to discover how the seismic waves generate a change in pore fluid pressure. We constrain a mechanism for seismically-induced pore pressure changes by studying coseismic water level drops at a well in Grants Pass, Oregon. Water level drops at the site have been associated with earthquakes for nearly 20 years. High-sample rate (up to 1 Hz) digital water level data is available for the two coseismic drops that have occurred since 1994. The approach of this study is to use the amplification of the seismic waves in the well to constrain variations of the aquifer properties during the water level drops. We find that the amplification of the seismic waves in the well is consistent with standard theory for 7 digitally recorded events without drops, but during an earthquake with a drop a dramatic change in amplification occurs during the passage of the Rayleigh waves. The change in amplification indicates that the transmissivity increases by a factor of 50 during the 11 cm coseismic water level drop accompanying the 1999 Mw=7.5 1999 Oaxaca, Mexico earthquake. Based on these observations, we propose a new model for coseismic pore pressure changes. Drops occur if an earthquake occurs when the well has become temporarily clogged by a solid precipitate or sediment. The seismic shaking induces a flow which removes the obstruction. Once a barrier is removed, water flows rapidly to generate dramatic

  19. Slow fault propagation in serpentinite under conditions of high pore fluid pressure

    NASA Astrophysics Data System (ADS)

    French, Melodie E.; Zhu, Wenlu

    2017-09-01

    The rupture, localization, and slip of faults in serpentinite were studied under varying pore fluid pressure conditions to understand deformation mechanisms potentially responsible for slow slip in fault zones. Experiments were conducted at a constant effective confining pressure of 10 MPa and under pore fluid pressures from 0 to 120 MPa and at temperatures from 23 to 110 °C. With no fluid pressure, faulting occurs rapidly and audibly, and the duration of failure increases monotonically with increasing fluid pressure and temperature. Although non-dilatant during initial strain hardening, the serpentinite dilates during strain weakening concomitant with fault rupture and slip. Non-dilatant strain hardening occurs by microcracking along serpentine basal planes and grain boundaries and rarely in mode I orientations, consistent with previous studies. Dilatant fault rupture produces a network of transgranular shear fractures in conjugate orientations, generally with one dominant fracture. Structural observations show that as fluid pressure increases, the number of transgranular fractures increases. We propose that when faulting occurs over a distributed zone rather than a pre-existing principal slip surface, dilatant hardening causes deformation to migrate. This process causes an increase in slip weakening distance and fracture energy at elevated fluid pressures that can lead to more stable failure. Further, thermally-activated processes caused deformation at propagating crack tips, which also increases the slip weakening distance and the effective fracture energy with increasing temperature. Given the geologic settings for slow slip, our results indicate that high fluid pressure, distributed deformation, and thermally-activated processes may all contribute to slow fault rupture and slip.

  20. Control of pore fluid pressure on depth of emplacement of magmatic sills: An experimental approach

    NASA Astrophysics Data System (ADS)

    Gressier, Jean-Baptiste; Mourgues, Regis; Bodet, Ludovic; Matthieu, Jean-Yves; Galland, Olivier; Cobbold, Peter

    2010-06-01

    In sedimentary basins, the emplacement of magmatic sills tends to occur within rock of low mechanical competence and permeability, such as shale. This often contains pore fluids at abnormally high pressure. We first theoretically show that, in anisotropic media, the higher the pore fluid pressure, the deeper the sill emplacement. Then we introduce a new technique for analogue modelling of such intrusive bodies under conditions of fluid overpressure (greater than hydrostatic), which corroborate the theoretical analysis. As an analogue of brittle sediment, we use a diatomite powder. This material is a dry, fine-grained, frictional, cohesive and permeable material. As an analogue for magma, we take a silicone putty (RTV silicone), which is at first Newtonian, but then solidifies at room temperature. We use compressed air as a pore fluid. Under these experimental conditions, we investigate the intrusion of magma into the host powder under various fluid overpressures. In homogeneous diatomite powder, having uniform cohesion, intrusive bodies are segmented dykes. These become feeders to sills, if the fluid overpressure exceeds the weight of overburden. Where the sedimentary column has a horizontal discontinuity in strength, the transition from dyke to sill occurs at a smaller overpressure (hydrostatic < λex < 1). As a possible illustration of these results, we consider sills within source rocks of the Neuquén Basin and of the Parana Basin, both in South America, where overpressure may have resulted from maturation of organic material.

  1. Predicting the Influence of Pore Characteristics on Ductility of Thin-Walled High Pressure Die Casting Magnesium

    SciTech Connect

    Sun, Xin; Choi, Kyoo Sil; Li, Dongsheng

    2013-06-10

    In this paper, a two-dimensional microstructure-based finite element modeling method is adopted to investigate the effects of porosity in thin-walled high pressure die casting Mg materials on their ductility. For this purpose, the cross-sections of AM50 and AM60 casting samples are first examined using optical microscope to obtain the overall information on the pore characteristics. The experimentally quantified pore characteristics are then used to generate a series of synthetic microstructures with different pore sizes, pore volume fractions and pore size distributions. Pores are explicitly represented in the synthetic microstructures and meshed out for the subsequent finite element analysis. In the finite element analysis, an intrinsic critical strain value is used for the Mg matrix material, beyond which work-hardening is no longer permissible. With no artificial failure criterion prescribed, ductility levels are predicted for the various microstructures in the form of strain localization. Mesh size effect study is also conducted, from which a mesh size dependent critical strain curve is determined. A concept of scalability of pore size effects is then presented and examined with the use of the mesh size dependent critical strain curve. The results in this study show that, for the regions with lower pore size and lower volume fraction, the ductility generally decreases as the pore size and pore volume fraction increase whereas, for the regions with larger pore size and larger pore volume fraction, other factors such as the mean distance between the pores begin to have some substantial influence on the ductility. The results also indicate that the pore size effects may be scalable for the models with good-representative pore shape and distribution with the use of the mesh size dependent critical strain curve.

  2. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    NASA Technical Reports Server (NTRS)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  3. Recharge and Transient Pore Pressure Propagation in Steep Alpine Mountain Slopes near Poschiavo, Switzerland

    NASA Astrophysics Data System (ADS)

    de Palézieux, Larissa; Loew, Simon; Zwahlen, Peter

    2017-04-01

    Within the scope of planning a hydropower pump storage plant in the Poschiavo valley by Lagobianco SA (Repower AG), numerous cored boreholes with depths of 50 to 300 m were drilled at elevations between 963 and 2538 m a.s.l.. In several boreholes Lugeon and transient pressure packer tests were executed at various depths and pore water pressure sensors were properly installed in short monitoring intervals. Several of the boreholes intersect large suspended rock slides showing the characteristic zones of highly fragmented rock mass above a kakirite layer of several tens of meters thickness. This study presents long term transient pressure records from these deep boreholes and relates them to seasonal recharge trends from snow melt and summer rainstorm events. Annual pore pressure amplitudes at depths between 45 and 278 meters, range between 4 and 40 meters. Recharge from snow melt water production is obtained from the Degree-Day Method (Rango and Martinec, 1995), despite a considerable distance between the meteorological station and the location of the boreholes. First estimations of storage properties of the aquifers intersected by the boreholes are determined by fitting a combined snow melt and precipitation pressure function to the observed (delayed and attenuated) pore pressure records using a convolution of the one-dimensional pressure diffusion equation for a semi-infinite aquifer of constant thickness (De Marsily, 1986). Initial hydraulic conductivity values were taken directly from hydraulic tests executed by Lagobianco SA in similar rock types (Figi et al., 2014). For most boreholes this strongly simplified approach yields impressively good fits of the transient pressure records and specific storage/yield values, which vary significantly as a function of sensor depth below the piezometric level. Values range from 1e-6 m-1 to 5e-4 m-1 for confined gneiss-schists aquifers and around 3e-2 m-1 for phreatic aquifers, where pore pressure sensors are located only

  4. Quantification of in situ pore pressure and stress in regions of low frequency earthquakes and anomalously low seismic velocity at the Nankai Trough

    NASA Astrophysics Data System (ADS)

    Kitajima, H.; Saffer, D. M.

    2012-12-01

    LVZ's are at shear failure defined by a critical state stress condition, we estimate that effective vertical stress in the LVZ ranges from 15 MPa at 13 km landward of the trench, to 41 MPa at a distance of 55 km. The maximum horizontal effective stress ranges from 41-124 MPa over this region. Excess pore fluid pressure ranges from 15-81 MPa, corresponding to modified pore pressure ratios, λ* of 0.44-0.73. If LVZ is composed dominantly of sandstones, both the effective vertical and horizontal stresses would be lower, and the excess pore pressure would be higher, with pore pressure ratios λ* = 0.31-0.90. Our results suggest that the sediments have been loaded under poorly drained conditions, and that pore fluids support ≥~53-91 % of the overburden stress along the base of the accretionary wedge across the outer forearc. The low effective stress should lead to a mechanically weak plate boundary, and is spatially correlated with well-located low-frequency earthquakes in the outer accretionary wedge. The heterogeneous distribution of inferred pore pressure also suggests that fluid sources and drainage are localized and possibly transient.

  5. Earthquake Fracture Energies and Weakening of Faults by Thermal Pressurization of Pore Fluid

    NASA Astrophysics Data System (ADS)

    Rice, J. R.

    2003-12-01

    Seismic inferences of fracture energy G constrain how fault strength degrades during slip and allow testing of candidate physical mechanisms. Recently G has been estimated by interpreting parameters from seismic slip inversions within a self-healing rupture model (Rice, Sammis and Parsons, 2003), and by studying the scaling of radiated energy and stress drop with earthquake size (Abercrombie and Rice, 2003). Those and earlier studies suggest that for larger events (slip > 0.1 m), G ranges from 0.1 to 10 MJ/m2 with average of 2-4 MJ/m2. There is a clear trend for G to increase with slip over the broad range from mm to m slip. Sibson-Lachenbruch thermal pressurization of pore water is examined as a possible general fault weakening mechanism for large crustal events. For adiabatic and undrained conditions, with strength given by the effective stress law with a constant friction coefficient f, the thermal properties of water in this context (Lachenbruch, 1980; Mase and Smith, 1988) lead to G = 1.7 (σ n - po) (1 + r) h. Here h is shearing zone thickness, σ n is normal stress, assumed constant during slip, po is ambient pore pressure, and r is the ratio fractional volume change of pore space per unit pore pressure increase divided by the compressibility of the pore fluid. Dilatancy is neglected; if confined to only the early phases of slip, it decreases po from ambient and so increases G, but the effect may be modest. The model predicts exponential decay of strength with slip, with e-folding slip distance 1.7 (1 + r) h / f. The total temperature rise in K is ≈ 0.6 (1 + r) (σ n - po) where the latter factor is in MPa. Estimating r = 1-2 and evaluating σ n - po as overburden minus hydrostatic pore pressure at 7 km as a representative centroidal depth for large crustal events, we obtain G ≈ 1-6 MJ/m2 for h = 2 to 10 mm. Shear zone thicknesses towards the lower end of such a range are suggested by recent field studies (Chester and Chester, 1998), which identify a

  6. Relations between hydrology and velocity of a continuously moving landslide-evidence of pore-pressure feedback regulating landslide motion?

    USGS Publications Warehouse

    Schulz, W.H.; McKenna, J.P.; Kibler, J.D.; Biavati, G.

    2009-01-01

    We measured displacement, pore-water pressure, and climatic conditions for 3 years at the continuously moving Slumgullion landslide in Colorado, USA. The landslide accelerated when pore-water pressure increased within the landslide body, but this occurred as pore-water pressure decreased along the landslide margin. The decrease probably occurred in response to shear-induced soil dilation at rates greater than pore-pressure diffusion and likely increased resistance to shear displacement and resulted in landslide deceleration. This dilative strengthening has been experimentally observed and explained theoretically, but not previously identified during field studies. Although landslide displacement should have exceeded that required to achieve critical-state density of shear boundaries, observed relocation of these boundaries indicates that shearing is episodic at fixed locations, so it permits renewed dilative strengthening when "fresh" soil is sheared. Thus, dilatant strengthening may be a considerable mechanism controlling landslide velocity, even for landslides that have continuously moved great distances. ?? Springer-Verlag 2009.

  7. 3-D Modeling of Pore Pressure Diffusion Beneath Koyna and Warna Reservoirs, Western India

    NASA Astrophysics Data System (ADS)

    Yadav, Amrita; Gahalaut, Kalpna; Purnachandra Rao, N.

    2017-05-01

    The mechanism of reservoir-triggered seismicity is well-understood and explains the earthquake occurrence at different reservoir sites. It can be attributed to the stresses due to water loading and to changes in fluid pressure in pores within the rock matrix. In the present study a 3-D fluid flow numerical model is used to investigate the pore pressure diffusion as a cause for continued seismicity in the Koyna-Warna region in western India. It is shown that reservoir water level fluctuations are sufficient to trigger earthquakes at the seismogenic depths in the region. Our numerical model suggests that a vertical fault with hydraulic conductivity in the range 2-6 m/day facilitates the diffusion of pressure at focal depths of earthquakes in the Koyna-Warna region. Also, for triggering of earthquakes a higher vertical conductivity is required for the Warna region than for the Koyna region. A lag of two months period is found between the maximum water level and the significant hydraulic head required to trigger earthquakes at the focal depth using the appropriate hydraulic conductivity for both the reservoirs.

  8. 3-D Modeling of Pore Pressure Diffusion Beneath Koyna and Warna Reservoirs, Western India

    NASA Astrophysics Data System (ADS)

    Yadav, Amrita; Gahalaut, Kalpna; Purnachandra Rao, N.

    2017-03-01

    The mechanism of reservoir-triggered seismicity is well-understood and explains the earthquake occurrence at different reservoir sites. It can be attributed to the stresses due to water loading and to changes in fluid pressure in pores within the rock matrix. In the present study a 3-D fluid flow numerical model is used to investigate the pore pressure diffusion as a cause for continued seismicity in the Koyna-Warna region in western India. It is shown that reservoir water level fluctuations are sufficient to trigger earthquakes at the seismogenic depths in the region. Our numerical model suggests that a vertical fault with hydraulic conductivity in the range 2-6 m/day facilitates the diffusion of pressure at focal depths of earthquakes in the Koyna-Warna region. Also, for triggering of earthquakes a higher vertical conductivity is required for the Warna region than for the Koyna region. A lag of two months period is found between the maximum water level and the significant hydraulic head required to trigger earthquakes at the focal depth using the appropriate hydraulic conductivity for both the reservoirs.

  9. An evaluation of factors influencing pore pressure in accretionary complexes: Implications for taper angle and wedge mechanics

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    2006-01-01

    At many subduction zones, accretionary complexes form as sediment is off-scraped from the subducting plate. Mechanical models that treat accretionary complexes as critically tapered wedges of sediment demonstrate that pore pressure controls their taper angle by modifying basal and internal shear strength. Here, we combine a numerical model of groundwater flow with critical taper theory to quantify the effects of sediment and de??collement permeability, sediment thickness, sediment partitioning between accretion and underthrusting, and plate convergence rate on steady state pore pressure. Our results show that pore pressure in accretionary wedges can be viewed as a dynamically maintained response to factors which drive pore pressure (source terms) and those that limit flow (permeability and drainage path length). We find that sediment permeability and incoming sediment thickness are the most important factors, whereas fault permeability and the partitioning of sediment have a small effect. For our base case model scenario, as sediment permeability is increased, pore pressure decreases from near-lithostatic to hydrostatic values and allows stable taper angles to increase from ??? 2.5?? to 8??-12.5??. With increased sediment thickness in our models (from 100 to 8000 m), increased pore pressure drives a decrease in stable taper angle from 8.4??-12.5?? to 15?? to <4??) with increased sediment thickness (from <1 to 7 km). One key implication is that hydrologic properties may strongly influence the strength of the crust in a wide range of geologic settings. Copyright 2006 by the American Geophysical Union.

  10. Estimation of the pore pressure distribution from three dimensional groundwater flow model at mine sites in Korea

    NASA Astrophysics Data System (ADS)

    Kang, Sangsoo; Jang, Myounghwan; Kim, Gyoungman; Kim, Donghui; Kim, Daehoon; Baek, Hwanjo

    2016-04-01

    Mining activities continually change the groundwater flow and associated pore pressure distributions within the rockmass around the mine openings or the open-pit bench during the operational periods. As the pore pressure distributions may substantially affect the mechanical behaviour or stability of the rockmass, it is important to monitor the variation of pore pressure incurred by mining operation. The pore pressure distributions within the rockmass can be derived using a two- or three-dimensional finite element groundwater flow model, adopted to simulate the groundwater flow. While the groundwater inflow at mines has generally been dealt with respect to the working environment, detailed case studies on the distribution of pore water pressure related to the stability analysis of mine openings have been relatively rare in Korea. Recently, however, as the health and safety problems are emerged for sustainable mining practice, these issues are of the major concerns for the mining industries. This study aims to establish a three dimensional groundwater flow model to estimate the pore pressure distributions in order to employ as an input parameter for numerical codes such as the FLAC 3D. Also, the groundwater flow simulated can be used for de-watering design at a mine site. The MINEDW code, a groundwater flow model code specifically developed to simulate the complicated hydro-geologic conditions related to mining, has mainly been used in this study. Based on the data collected from field surveys and literature reviews, a conceptual model was established and sensitivity analysis was performed.

  11. Wave-induced pore pressure and effective stresses in a porous seabed with variable permeability

    SciTech Connect

    Jeng, D.S.; Seymour, B.R.

    1996-12-31

    An evaluation of wave-induced soil response is particularly useful for geotechnical and coastal engineers involved in the design of foundations for offshore structures. To simplify the mathematical procedure, most theories available for the wave/seabed interaction problem have assumed a porous seabed with uniform permeability, despite strong evidence of variable permeability. This paper proposes an analytical solution for the wave induced soil response in a porous seabed with variable permeability. Verification is available through reduction to the simple case of uniform permeability. The numerical results indicate that the effect of variable soil permeability on pore pressure and effective stresses is significant.

  12. Hydromechanical Rock Mass Fatigue in Deep-Seated Landslides Accompanying Seasonal Variations in Pore Pressures

    NASA Astrophysics Data System (ADS)

    Preisig, Giona; Eberhardt, Erik; Smithyman, Megan; Preh, Alexander; Bonzanigo, Luca

    2016-06-01

    The episodic movement of deep-seated landslides is often governed by the presence of high pore pressures and reduced effective stresses along active shear surfaces. Pore pressures are subject to cyclic fluctuation under seasonal variations of groundwater recharge, resulting in an intermittent movement characterized by acceleration-deceleration phases. However, it is not always clear why certain acceleration phases reach alarming levels without a clear trigger (i.e., in the absence of an exceptional pore pressure event). This paper presents a conceptual framework linking hydromechanical cycling, progressive failure and fatigue to investigate and explain the episodic behavior of deep-seated landslides using the Campo Vallemaggia landslide in Switzerland as a case study. A combination of monitoring data and advanced numerical modeling is used. The principal processes forcing the slope into a critical disequilibrium state are analyzed as a function of rock mass damage and fatigue. Modeling results suggest that during periods of slope acceleration, the rock slope experiences localized fatigue and gradual weakening through slip along pre-existing natural fractures and yield of critically stressed intact rock bridges. At certain intervals, pockets of critically weakened rock may produce a period of enhanced slope movement in response to a small pore pressure increase similar to those routinely experienced each year. Accordingly, the distribution and connectivity of pre-existing permeable planes of weakness play a central role. These structures are often related to the rock mass's tectonic history or initiate (and dilate) in response to stress changes that disturb the entire slope, such as glacial unloading or seismic loading via large earthquakes. The latter is discussed in detail in a companion paper to this (Gischig et al., Rock Mech Rock Eng, 2015). The results and framework presented further demonstrate that episodic movement and progressive failure of deep

  13. Experimental Studies of Dynamic Fault Weakening Due to Thermal Pressurization of Pore Fluids

    NASA Astrophysics Data System (ADS)

    Goldsby, David; Tullis, Terry; Platt, John; Okazaki, Keishi

    2016-04-01

    High-velocity friction experiments and geophysical observations suggest that mature faults weaken dramatically during seismic slip. However, while many coseismic weakening mechanisms have been proposed, it is still unclear which mechanisms are most important or how the efficiency of weakening varies within the seismogenic zone. Thermal pressurization is one possible coseismic weakening mechanism driven by the thermal expansion of native pore fluids, which leads to elevated pore pressures and significant coseismic weakening. While thermal pressurization has been studied theoretically for many decades, and invoked in recent earthquake simulations, its activation in laboratory experiments has remained elusive. Several high-speed friction studies have yielded indirect evidence for thermal pressurization, yet none has directly linked with existing theoretical models or the relevant physical parameters, such as permeability, slip, and slip rate, that control the weakening rate. To fill this gap, we are conducting thermal pressurization experiments on fluid-saturated, low-permeability rocks (Frederick diabase) at slip rates up to ~5 mm/s, at constant confining pressures in the range 21-149 MPa and initial imposed pore pressures in the range 10-25 MPa. The impractically low permeability of the as-is diabase, ~10-23 m2, is increased prior to the test by thermal cracking, yielding measured permeabilities in the range 1.3*10-18 to 6.1*10-19 m2. These values of permeability are high enough to allow sample saturation over one to several days, but low enough to confine the elevated pore pressures generated by frictional heating during rapid sliding. Our experiments reveal a rapid decay of shear stress following a step-change in velocity from 10 μm/s to 4.8 mm/s. In one test, the decrease in shear stress of ~25% over the first 28 mm of slip at 4.8 mm/s agrees closely with the theoretical solution for slip on a plane (Rice [2006]), with an inferred slip-weakening distance of ~500

  14. Coupling of Pore Pressure and Ground Motion: Further Studies using Data Recorded at the NEES@UCSB Wildlife Station

    NASA Astrophysics Data System (ADS)

    Seale, S. H.; Lavallee, D.; Archuleta, R. J.; Steidl, J. H.

    2012-12-01

    Pore pressure built up during an earthquake and the hazard associated with soil liquefaction present a major challenge for our society, as has been dramatically illustrated by recent large events (e.g. the 2011 Tohoku-oki, Japan, earthquake). There is consensus among scientists that a better assessment of the liquefaction risk requires a better understanding of the coupling between pore pressure and ground motion time histories. There is a basic need to investigate coupling as a function of the frequency content of the ground motion. The 2010 M7.2 El Mayor-Cucapah event has provided a remarkable opportunity to investigate and model the coupling. The event was well recorded at the NEES@UCSB Wildlife station located 110 km from the hypocenter. The station is equipped with three-component strong-motion accelerometers at the surface and in boreholes at various depths and with pore pressure transducers located in a saturated, liquefiable layer. The recorded pore pressure and ground motion time histories both have frequency content that is a function of time. We have applied a wavelet decomposition technique to the El Mayor ground motion and pore pressure data, looking for a linear relationship between the signals. The analysis shows that the early P-wave accelerations (vertical component) initiate pore pressure response. However, the pore pressure records contain a low-frequency component that dominates the signal with no corresponding low-frequency component in the ground motion signals recorded near-by. Although uncommon, a similar behavior has been also reported in the literature for pore pressure signals recoded during the 1980 Mammoth Lakes, California, earthquake. We have extended this work to the analysis of 4 other seismic events that have induced an increase in pore pressure at WLA. As the response of pore pressure is potentially a local phenomenon, we have restricted our analysis to recordings from the same site. These events include the M5.8 Ocotillo

  15. Methods and apparatuses for measurement of the strengths, pore pressures, and mechanical properties of low permeability geologic materials

    SciTech Connect

    Steiger, R.P.

    1993-07-13

    Triaxial test apparatus is described for testing rock samples in a housing fillable with confining fluid for providing confining pressure, the housing having a channel for introduction therein and removal therefrom of the confining fluid, the housing having an opening there through which a portion of a load piston sealingly extends for providing a load on the sample, the triaxial test apparatus comprising sample mounting means for mounting the sample within the housing, the sample mounting means including a top end cap for mounting at the top and a bottom end cap for disposition at the bottom of the sample, the bottom end cap housing a body and a pore pressure channel in the body in fluid communication with the bottom of the sample and into which flows sample fluid expelled from the sample during testing, the sample fluid contacting an inert fluid in the pore pressure channel, a bottom end cap chamber in the body of the bottom end cap in fluid communication with the pore pressure channel, the bottom end cap chamber for containing an amount of the inert fluid, a pore pressure transducer disposed in the bottom end cap chamber for reacting to and sensing changes in the amount of sample fluid expelled from the sample during testing, wiring connected to the pore pressure transducer and extending therefrom and out of the body, the wiring connectable to a system for monitoring and recording changes sensed by the pore pressure transducer, the pore pressure channel and the bottom end cap chamber filled with the inert fluid, the inert fluid immiscible with the sample fluid, at least one flexible impermeable jacket for enclosing the surface of the sample other than its ends and preventing the confining fluid from directly contacting the sample and preventing sample fluid from being expelled from the portion of the sample covered by the jacket, and the bottom end cap suitable for mounting on a load cell mounted within the housing.

  16. Along-fault pore-pressure evolution during a slow-slip event in Guerrero, Mexico

    NASA Astrophysics Data System (ADS)

    Frank, W. B.; Shapiro, N. M.; Husker, A. L.; Kostoglodov, V.; Bhat, H. S.; Campillo, M.

    2015-03-01

    Slow earthquakes are important constituents of the seismic cycle and are involved in the stress transfer between the viscously slipping portion of the plate interface and the seismogenic zone. Their occurrence is likely associated with the near-lithostatic pore pressure in the slow earthquake source region, where fluids might modify fault friction and whose presence is indicated by high ratios of compressional (P)-wave velocity to shear (S)-wave velocity observed at the interface between the subducting plate and the overlying crust. Here we compare two slow earthquake phenomena observed in the Guerrero region of the Mexican subduction zone: low-frequency earthquakes (LFEs) and a slow-slip event (SSE) recorded by GPS. We observe variations of the LFE occurrence rates over month-long time scales during a large SSE that we interpret as a manifestation of transient changes in the fault shear strength. We argue that these transient changes are caused by a pore pressure fluctuation that migrates updip along the subduction interface. This mechanism suggests that fluids do not only passively weaken the plate interface but also play an active role in slow earthquake source regions.

  17. Tremor-tide correlations and near-lithostatic pore pressure on the deep San Andreas fault.

    PubMed

    Thomas, Amanda M; Nadeau, Robert M; Bürgmann, Roland

    2009-12-24

    Since its initial discovery nearly a decade ago, non-volcanic tremor has provided information about a region of the Earth that was previously thought incapable of generating seismic radiation. A thorough explanation of the geologic process responsible for tremor generation has, however, yet to be determined. Owing to their location at the plate interface, temporal correlation with geodetically measured slow-slip events and dominant shear wave energy, tremor observations in southwest Japan have been interpreted as a superposition of many low-frequency earthquakes that represent slip on a fault surface. Fluids may also be fundamental to the failure process in subduction zone environments, as teleseismic and tidal modulation of tremor in Cascadia and Japan and high Poisson ratios in both source regions are indicative of pressurized pore fluids. Here we identify a robust correlation between extremely small, tidally induced shear stress parallel to the San Andreas fault and non-volcanic tremor activity near Parkfield, California. We suggest that this tremor represents shear failure on a critically stressed fault in the presence of near-lithostatic pore pressure. There are a number of similarities between tremor in subduction zone environments, such as Cascadia and Japan, and tremor on the deep San Andreas transform, suggesting that the results presented here may also be applicable in other tectonic settings.

  18. Impact in dense granular suspensions: crucial role of dilatancy and pore pressure feedback

    NASA Astrophysics Data System (ADS)

    Forterre, Yoel; Soundar Jerome, J. John; Vandenberghe, Nicolas; Duchemin, Laurent

    2013-11-01

    We investigate the impact of a rigid sphere onto a granular paste made of non-buoyant glass beads mixed with a liquid under gravity. We show that the initial volume fraction of the granular packing has a critical influence on the impact behavior. For loose packing, the ball sinks in the granular medium as in a liquid, giving rise to a collapsing cavity and a central jet as observed with fine powders in air. By contrast, for dense packing, the ball stops as soon as it hits the surface and its kinetic energy is almost instantly dissipated. We interpret this ``liquid-solid'' transition as the volume fraction change by a coupling between dilatancy effects and the liquid pore pressure during the impact. Dynamic pore pressure measurements and a simple diphasic model taking into account dilatancy support this mechanism. Our results show that ``shear-thickening-like'' phenomena in granular suspensions can arise from transient diphasic coupling rather than from the intrinsic rheology of the material. This work was supported by ANR through the program No. ANR-11-JS09-005-01.

  19. Pore Structure and Limit Pressure of Gas Slippage Effect in Tight Sandstone

    PubMed Central

    You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi

    2013-01-01

    Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit pressure increases with the decreasing in permeability and has close relation with pore structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment. PMID:24379747

  20. Pore structure and limit pressure of gas slippage effect in tight sandstone.

    PubMed

    You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi; Kong, Lie

    2013-01-01

    Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit pressure increases with the decreasing in permeability and has close relation with pore structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment.

  1. Pore Pressure prediction in shale gas reservoirs using neural network and fuzzy logic with an application to Barnett Shale.

    NASA Astrophysics Data System (ADS)

    Aliouane, Leila; Ouadfeul, Sid-Ali; Boudella, Amar

    2015-04-01

    The main goal of the proposed idea is to use the artificial intelligence such as the neural network and fuzzy logic to predict the pore pressure in shale gas reservoirs. Pore pressure is a very important parameter that will be used or estimation of effective stress. This last is used to resolve well-bore stability problems, failure plan identification from Mohr-Coulomb circle and sweet spots identification. Many models have been proposed to estimate the pore pressure from well-logs data; we can cite for example the equivalent depth model, the horizontal model for undercompaction called the Eaton's model…etc. All these models require a continuous measurement of the slowness of the primary wave, some thing that is not easy during well-logs data acquisition in shale gas formtions. Here, we suggest the use the fuzzy logic and the multilayer perceptron neural network to predict the pore pressure in two horizontal wells drilled in the lower Barnett shale formation. The first horizontal well is used for the training of the fuzzy set and the multilayer perecptron, the input is the natural gamma ray, the neutron porosity, the slowness of the compression and shear wave, however the desired output is the estimated pore pressure using Eaton's model. Data of another horizontal well are used for generalization. Obtained results clearly show the power of the fuzzy logic system than the multilayer perceptron neural network machine to predict the pore pressure in shale gas reservoirs. Keywords: artificial intelligence, fuzzy logic, pore pressure, multilayer perecptron, Barnett shale.

  2. Pore-pressure diffusion based on analysis and characterization of microseismicity in central Arkansas

    NASA Astrophysics Data System (ADS)

    Ogwari, Paul Otieno

    Part 1: Between August 2010 and June 2011, an intense sequence of induced earthquakes occurred along the Guy-Greenbrier fault in central Arkansas due to fluid injection at nearby waste disposal wells. A previous study by Horton (2010) limited to ˜1,000 earthquakes having md > ˜2.0 illuminated the ˜13km fault. We present an updated catalogue of 17,395 earthquakes that appears complete between 0 <= ml <= 4.4 for the initial part of the sequence between August 2010 and October 20, 2010 located using an updated 1D velocity model for the region. The inclusion of the small magnitude events reveals that seismicity starts below the SRE injection well a month earlier than estimated using only md >2 events. During this period of time, the seismicity migrated from north to south enhancing the resolution of three joined sections that form the northern ˜7.3km portion of the fault, which plunges southwards. The seismogenic zone covers the lower portion of the Paleozoic sedimentary layers and extends into the crystalline Precambrian basement (˜3km < z 3 events constrained within the basement. A b-value of 1.1 was obtained for the updated catalog during this period with the b-value varying between 1.45 and 0.74 for different clusters of events. The seismicity pattern at depth is coincident with structural geologic features observed within the Fayetteville Shale (at ˜1500m depth). Part 2: We model pore-pressure diffusion caused by pressurized waste-fluid injection at two nearby wells, and then compare the build-up of pressure with the observed initiation and migration of earthquakes during the early part of the 2010-2011 Guy-Greenbrier earthquake swarm. Pore pressure diffusion is calculated using MODFLOW 2005 that allows the actual injection histories (volume/day) at the two wells to diffuse through a fractured and faulted 3D aquifer system representing the eastern Arkoma basin. The aquifer system is calibrated using the observed well "drawup" following well shut-in at three

  3. A combined experimental and numerical study of pore water pressure variations in sub-permafrost groundwater

    NASA Astrophysics Data System (ADS)

    Rivière, A.; Anne, J.; Goncalves, J.

    2013-12-01

    The past few decades have seen a rapid development and progress in research on past and current hydrologic impacts of permafrost evolution. In permafrost area, groundwater is subdivided into two zones: supra-permafrost and sub-permafrost which are separated by permafrost. Knowledge of the sub-permafrost aquifers is often lacking due to the difficulty to access those systems. The few available data show that this aquifers are generally artesian below the continuous permafrost. In the literature, there are two plausible explanations for the relatively high pore pressures in the sub-permafrost aquifer; the recharge related to the ice sheet melting and the expulsion of water related to the ice expansion. In this study, we investigated areas where ice sheets have never developed like in the Paris basin region. The ice expansion induces also soil surface uplift. Our study focuses on modifications of pore water pressure in the sub-permafrost aquifer and the soil surface motion during the permafrost development (freezing front deepening). To fill in the gaps to the field data availability, we developed an experimental approach. Experimental design was undertaken at the Laboratory M2C (Université de Caen-Basse Normandie, CNRS, France). The device consisted in a 2 m2 box insulated at all sides except on the top where a surface temperature was prescribed. The box is filled with silty sand of which hydraulics and thermal parameters are known. Soil temperatures, pore water pressure and soil motion are continuously recorded at different elevations in the sand-box. We developed a two-dimensional transient fully coupled heat and water transport model to simulate thawing and freezing processes taking into account the phase change (Latent heat effects). The balance equations are solved using of a finite difference numerical scheme. Experimental results are used to verify the implementation of the hydro-mechanical processes in our numerical simulations. Experimental and numerical

  4. Pore water pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne

    2010-05-01

    Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of water upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the pressurization of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of pore water pressure of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of water associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are

  5. Blood pressure, excess weight and level of physical activity in students of a public university.

    PubMed

    Martins, Maria do Carmo de Carvalho e; Ricarte, Irapuá Ferreira; Rocha, Cláudio Henrique Lima; Maia, Rodrigo Batista; Silva, Vitor Brito da; Veras, André Bastos; Filho, Manoel Dias de Souza

    2010-08-01

    High blood pressure, excess weight and sedentary lifestyle are important risk factors for cardiovascular diseases, and they are closely associated. To evaluate the nutritional status, level of physical activity and blood pressure levels of students of Universidade Federal do Piauí, Teresina, Brazil. Cross-sectional study with a sample of 605 students (46.1% males and 53.9% females), with a mean age of 21.7 ± 3.7 years. The nutritional status was classified according to body mass index (BMI), and central adiposity according to waist circumference (WC). The level of physical activity was evaluated using the short version of the International Physical Activity Questionnaire (IPAQ). Elevated blood pressure was defined as systolic blood pressure > 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg. The prevalence of elevated blood pressure was 9.7%, and was higher among men. Excess weight (BMI > 25 kg/m(2)) was found in 18.2% of the students, with overweight and obesity rates of 15.2% and 3%, respectively. Abdominal obesity was found in 2.4% of the students regardless of gender, and sedentary lifestyle in 52%. The mean blood pressure increased with increasing BMI and WC. No association was found between the levels of physical activity and blood pressure. An association of increased body weight and waist circumference with higher blood pressure levels was observed among the participants. Instruments for an early assessment of the cardiovascular risk and preventive advice should be established for these young individuals.

  6. Understanding North Texas Seismicity: A Joint Analysis of Seismic Data and 3D Pore Pressure Modeling

    NASA Astrophysics Data System (ADS)

    DeShon, H. R.; Hornbach, M. J.; Ellsworth, W. L.; Oldham, H. R.; Hayward, C.; Stump, B. W.; Frohlich, C.; Olson, J. E.; Luetgert, J. H.

    2014-12-01

    In November 2013, a series of earthquakes began along a mapped ancient fault system near Azle, Texas. The Azle events are the third felt earthquake sequence in the Fort Worth (Barnett Shale) Basin since 2008, and several production and injection wells in the area are drilled to depths near the recent seismic activity. Understanding if and/or how injection and removal of fluids in the crystalline crust reactivates faults have important implications for seismology, the energy industry, and society. We assessed whether the Azle earthquakes were induced using a joint analysis of the earthquake data, subsurface geology and fault structure, and 3D pore pressure modeling. Using a 12-station temporary seismic deployment, we have recorded and located >300 events large enough to be recorded on multiple stations and 1000s of events during periods of swarm activity. High-resolution locations and focal mechanisms indicate that events occurred on NE-SW trending, steeply dipping normal faults associated with the southern end of the Newark East Fault Zone with hypocenters between 2-8 km depth. We considered multiple causes that might have changed stress along this system. Earthquakes resulting from natural processes, though perhaps unlikely in this historically inactive region, can be neither ruled out nor confirmed due to lack of information on the natural stress state of these faults. Analysis of lake and groundwater variations near Azle showed that no significant stress changes occurred prior to or during the earthquake sequence. In contrast, analysis of pore-pressure models shows that the combination of formation water production and wastewater injection near the fault could have caused pressure increases that induced earthquakes on near-critically stressed faults.

  7. From pore pressure modeling to seismic risk assessment - a fully-integrated modeling approach

    NASA Astrophysics Data System (ADS)

    Layland-Bachmann, C. E.; Foxall, W.; Doughty, C.; Savy, J. B.; Hutchings, L. J.

    2016-12-01

    Increased subsurface fluid injection accompanying oil, gas, and geothermal exploitation and carbon dioxide sequestration, among other fluid injection applications, has increased the potential impact of injection-induced seismicity over the last few years, escalating the need to model the underlying physical processes and to assess potential seismic hazard and risks. We are developing a method to assess the seismic impact of proposed fluid injection projects that combines fluid flow modeling and earthquake simulation with probabilistic seismic hazard analysis. We use the multi-phase, multi-component flow and transport model TOUGH2 code, which enables complex pore-pressure time histories on specific faults and fractures resulting from injection to be calculated. A recent addition to RSQSim, the code used for physics-based earthquake simulations, enables such pressure histories to be treated as external stressing factors added to stresses due to tectonic loading. Earthquake catalogs generated by RSQSim are used as input to the RiskCat code, which performs probabilistic seismic hazard and risk calculations based on time- and space-dependent seismicity frequency-magnitude distributions. We present an application of this integrated approach to hypothetical CO2 sequestration injection scenarios based on a simplified model of a faulted reservoir at King Island in the northern Sacramento Valley, California. Multiple pore-pressure distributions calculated by TOUGH2 for different injection scenarios are used as external stress inputs to RSQsim. By varying fault and other properties, we generate the multiple realizations of the seismic catalogs required by RiskCat to carry out probabilistic seismic hazard assessments that fully incorporate both epistemic and aleatory uncertainty distributions. We propose that simulation-based methods like this can be used during the pre-injection design phase of planned projects.

  8. Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures

    DOE PAGES

    Seoung, Donghoon; Cynn, Hyunchae; Park, Changyong; ...

    2014-09-01

    Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7 GPa and 250 °C, while Ag+ is reduced to metallic Ag and possibly oxidized to Ag2+. In contrast to krypton, xenon is retained within the pores of this zeolite after pressure releasemore » and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres.« less

  9. A thermodynamically consistent model for granular-fluid mixtures considering pore pressure evolution and hypoplastic behavior

    NASA Astrophysics Data System (ADS)

    Hess, Julian; Wang, Yongqi

    2016-11-01

    A new mixture model for granular-fluid flows, which is thermodynamically consistent with the entropy principle, is presented. The extra pore pressure described by a pressure diffusion equation and the hypoplastic material behavior obeying a transport equation are taken into account. The model is applied to granular-fluid flows, using a closing assumption in conjunction with the dynamic fluid pressure to describe the pressure-like residual unknowns, hereby overcoming previous uncertainties in the modeling process. Besides the thermodynamically consistent modeling, numerical simulations are carried out and demonstrate physically reasonable results, including simple shear flow in order to investigate the vertical distribution of the physical quantities, and a mixture flow down an inclined plane by means of the depth-integrated model. Results presented give insight in the ability of the deduced model to capture the key characteristics of granular-fluid flows. We acknowledge the support of the Deutsche Forschungsgemeinschaft (DFG) for this work within the Project Number WA 2610/3-1.

  10. Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures

    SciTech Connect

    Seoung, Donghoon; Cynn, Hyunchae; Park, Changyong; Choi, Kwang -Yong; Blom, Douglas A.; Evans, William J.; Kao, Chi -Chang; Vogt, Thomas; Lee, Yongjae

    2014-09-01

    Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7 GPa and 250 °C, while Ag+ is reduced to metallic Ag and possibly oxidized to Ag2+. In contrast to krypton, xenon is retained within the pores of this zeolite after pressure release and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres.

  11. Pore-Lining Composition and Capillary Breakthrough Pressure of Mudstone Caprocks: Sealing Efficiency of Geologic CO2 Storage Sites

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Dewers, T. A.; McPherson, B. J.; Kotula, P. G.

    2010-12-01

    Subsurface containment of CO2 is predicated on effective caprock sealing. Many previous studies have relied on macroscopic measurements of capillary breakthrough pressure and other petrophysical properties without direct examination of solid phases that line pore networks and directly contact fluids. However, pore-lining phases strongly contribute to sealing behavior through interfacial interactions among CO2, brine, and the mineral or non-mineral phases. Our high resolution (i.e., sub-micron) examination of the composition of pore-lining phases of several continental and marine mudstones indicates that sealing efficiency (i.e., breakthrough pressure) is governed by pore shapes and pore-lining phases that are not identifiable except through direct characterization of pores. Bulk X-ray diffraction data does not indicate which phases line the pores and may be especially lacking for mudstones with organic material. Organics can line pores and may represent once-mobile phases that modify the wettability of an originally clay-lined pore network. For shallow formations (i.e., < ~800 m depth), interfacial tension and contact angles result in breakthrough pressures that may be as high as those needed to fracture the rock—thus, in the absence of fractures, capillary sealing efficiency is indicated. Deeper seals have poorer capillary sealing if mica-like wetting dominates the wettability. We thank the U.S. Department of Energy’s National Energy Technology Laboratory and the Office of Basic Energy Sciences, and the Southeast and Southwest Carbon Sequestration Partnerships for supporting this work. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Vertical structure of pore pressure under surface gravity waves on a steep, megatidal, mixed sand-gravel-cobble beach

    NASA Astrophysics Data System (ADS)

    Guest, Tristan B.; Hay, Alex E.

    2017-01-01

    The vertical structure of surface gravity wave-induced pore pressure is investigated within the intertidal zone of a natural, steeply sloping, megatidal, mixed sand-gravel-cobble beach. Results from a coherent vertical array of buried pore pressure sensors are presented in terms of signal phase lag and attenuation as functions of oscillatory forcing frequency and burial depth. Comparison of the observations with the predictions of a theoretical poro-elastic bed response model indicates that the large observed phase lags and attenuation are attributable to interstitial trapped air. In addition to the dependence on entrapped air volume, the pore pressure phase and attenuation are shown to be sensitive to the hydraulic conductivity of the sediment, to the changing mean water depth during the tidal cycle, and to the redistribution/rearrangement of beach face material by energetic wave action during storm events. The latter result indicates that the effects on pore pressure of sediment column disturbance during instrument burial can persist for days to weeks, depending upon wave forcing conditions. Taken together, these results raise serious questions as to the practicality of using pore pressure measurements to estimate the kinematic properties of surface gravity waves on steep, mixed sand-gravel beaches.

  13. Vertical Structure of Pore Pressure Under Surface Gravity Waves on a Steep, Megatidal, Mixed Sand-Gravel-Cobble Beach

    NASA Astrophysics Data System (ADS)

    Guest, T.; Hay, A. E.

    2016-12-01

    The vertical structure of surface gravity wave-induced pore pressure is investigated within the intertidal zone of a steeply sloping, megatidal, mixed sand-gravel-cobble beach. Results from a coherent vertical array of buried pore pressure sensors are presented in terms of signal phase lag and attenuation as functions of frequency and burial depth. Comparison of the observations with the predictions of a theoretical poro-elastic bed response model indicates that the large observed phase lags and attenuation are attributable to interstitial trapped air. In addition to the dependence on entrapped air volume, the pore pressure phase and attenuation are shown to be sensitive to the hydraulic conductivity of the sediment, to the changing mean water depth during the tidal cycle, and to the redistribution/rearrangement of beach face material by energetic wave action during storm events. The latter result indicates that the effects on pore pressure of sediment column disturbance during instrument burial can persist for days to weeks, depending upon wave forcing conditions. Taken together, these results raise serious questions as to the practicality of using pore pressure measurements to estimate the kinematic properties of surface gravity waves on steep, mixed sand-gravel beaches.

  14. Excessive cardiac insulin signaling exacerbates systolic dysfunction induced by pressure overload in rodents

    PubMed Central

    Shimizu, Ippei; Minamino, Tohru; Toko, Haruhiro; Okada, Sho; Ikeda, Hiroyuki; Yasuda, Noritaka; Tateno, Kaoru; Moriya, Junji; Yokoyama, Masataka; Nojima, Aika; Koh, Gou Young; Akazawa, Hiroshi; Shiojima, Ichiro; Kahn, C. Ronald; Abel, E. Dale; Komuro, Issei

    2010-01-01

    Although many animal studies indicate insulin has cardioprotective effects, clinical studies suggest a link between insulin resistance (hyperinsulinemia) and heart failure (HF). Here we have demonstrated that excessive cardiac insulin signaling exacerbates systolic dysfunction induced by pressure overload in rodents. Chronic pressure overload induced hepatic insulin resistance and plasma insulin level elevation. In contrast, cardiac insulin signaling was upregulated by chronic pressure overload because of mechanical stretch–induced activation of cardiomyocyte insulin receptors and upregulation of insulin receptor and Irs1 expression. Chronic pressure overload increased the mismatch between cardiomyocyte size and vascularity, thereby inducing myocardial hypoxia and cardiomyocyte death. Inhibition of hyperinsulinemia substantially improved pressure overload–induced cardiac dysfunction, improving myocardial hypoxia and decreasing cardiomyocyte death. Likewise, the cardiomyocyte-specific reduction of insulin receptor expression prevented cardiac ischemia and hypertrophy and attenuated systolic dysfunction due to pressure overload. Conversely, treatment of type 1 diabetic mice with insulin improved hyperglycemia during pressure overload, but increased myocardial ischemia and cardiomyocyte death, thereby inducing HF. Promoting angiogenesis restored the cardiac dysfunction induced by insulin treatment. We therefore suggest that the use of insulin to control hyperglycemia could be harmful in the setting of pressure overload and that modulation of insulin signaling is crucial for the treatment of HF. PMID:20407209

  15. Monitoring and Analysis of Transient Pore Water Pressures in Large Suspended Rock Slides near Poschiavo, CH

    NASA Astrophysics Data System (ADS)

    de Palézieux, Larissa; Loew, Simon; Zwahlen, Peter

    2016-04-01

    Many mountain slopes in the Alps exhibit large compound rock slides or Deep Seated Gravitational Slope Deformations. Due to the basal rupture plane geometry and the cumulative displacement magnitude such landslide bodies are often strongly deformed, highly fractured and - at least locally - very permeable. This can lead to high infiltration rates and low phreatic groundwater tables. This is also the situation in the studied mountain slopes southwest of Poschiavo, where large suspended rockslides occur, with very little surface runoff at high elevations, and torrents developing only at the elevation of the basal rupture planes. Below the landslide toes, at altitudes below ca. 1700 m a.s.l., groundwater appears forming spring lines or distributed spring clusters. Within the scope of the design of a hydropower pump storage plant in the Poschiavo valley by Lagobianco SA (Repower AG), numerous cored and deep boreholes (of 50 to 300 m depth) have been drilled along the planned pressure tunnel alignement at elevations ranging from 963 to 2538 m a.s.l. in the years 2010 and 2012. In several boreholes Lugeon and transient pressure tests were executed and pore water pressure sensors installed in short monitoring sections at various depths. Most of these boreholes intersect deep rockslides in crystalline rocks and limestones, showing highly fragmented rock masses and cohesionless cataclastic shear zones of several tens of meters thickness. This study explores these borehole observations in landslides and adjacent stable slopes and links them to the general hydrologic and hydrogeologic framework. The analysis of the pore water pressure data shows significant variability in seasonal trends and short-term events (from snow melt and summer rain storms) and remarkable pressure differences over short horizontal and vertical distances. This reflects rock mass damage within landslide bodies and important sealing horizons at their base. Based on water balances, the estimated effective

  16. Effect of Gas Pores on Mechanical Properties of High-Pressure Die-Casting AM50 Magnesium Alloy.

    PubMed

    Jiang, Wei; Cao, Zhanyi; Liu, Liping; Jiang, Bo

    2016-08-01

    High-pressure die-casting (HPDC) AM50 tensile specimens were used to investigate characteristics of gas pores and its effect on mechanical properties of HPDC AM50 magnesium alloy. Combining microstructure morphology gained from optical microscopy, scanning electron microscopy (SEM), and three-dimensional (3D) reconstruction with the experimental data from uniaxial tensile testing, we pursued the relationship between gas pores and the mechanical properties of HPDC AM50 Mg alloy. Results indicate that comparing with 3D reconstruction models, 2D images like optical metallography images and SEM images have one-sidedness. Furthermore, the size and maximum areal fraction of gas pores have negative effects on the mechanical properties of HPDC AM50 Mg alloy. With increase of the maximum size of gas pores in the specimen, the ultimate tensile strength (UTS) and elongation decrease. In addition, with the maximum areal fraction becoming larger, both the UTS and elongation decrease linearly.

  17. Finite element analysis of land subsidence above depleted reservoirs with pore pressure gradient and total stress formulations

    NASA Astrophysics Data System (ADS)

    Gambolati, Giuseppe; Ferronato, Massimiliano; Teatini, Pietro; Deidda, Roberto; Lecca, Giuditta

    2001-04-01

    The solution of the poroelastic equations for predicting land subsidence above productive gas/oil fields may be addressed by the principle of virtual works using either the effective intergranular stress, with the pore pressure gradient regarded as a distributed body force, or the total stress incorporating the pore pressure. In the finite element (FE) method both approaches prove equivalent at the global assembled level. However, at the element level apparently the equivalence does not hold, and the strength source related to the pore pressure seems to generate different local forces on the element nodes. The two formulations are briefly reviewed and discussed for triangular and tetrahedral finite elements. They are shown to yield different results at the global level as well in a three-dimensional axisymmetric porous medium if the FE integration is performed using the average element-wise radius. A modification to both formulations is suggested which allows to correctly solve the problem of a finite reservoir with an infinite pressure gradient, i.e. with a pore pressure discontinuity on its boundary.

  18. Dependencies of pore pressure on elastic wave velocities and Vp/Vs ratio for thermally cracked gabbro

    NASA Astrophysics Data System (ADS)

    Nishimura, K.; Uehara, S. I.; Mizoguchi, K.

    2015-12-01

    Marine seismic refraction have found that there are high Vp/Vs ratio regions in oceanic crusts at subducting oceanic plates (e.g, Cascadia subduction zone (2.0-2.8) (Audet et al., 2009)). Previous studies based on laboratory measurements indicated that Vp/Vs ratio is high when porosity and/or pore pressure is high (Christensen, 1984; Peacock et al., 2011). Although several studies have investigated the relationships between fracture distributions and Vp, Vs (e.g., Wang et al., 2012; Blake et al., 2013), the relationships for rocks (e.g., gabbro and basalt) composing oceanic crust are still unclear. This study reports the results of laboratory measurements of Vp, Vs (transmission method) at controlled confining and pore pressure and estimation of Vp/Vs ratio for thermally cracked gabbro which mimic highly fractured rocks in the high Vp/Vs ratio zone, in order to declare the dependence of fracture distributions on Vp/Vs. For the measurements, we prepared three type specimens; a non-heated intact specimen, specimens heated up to 500 °C and 700 °C for 24 hours. Porosities of intact, 500 °C and 700 °C specimens measured under the atmospheric pressure are 0.5, 3.4 and 3.5%, respectively. Measurements were conducted at a constant confining pressure of 50 MPa, with decreasing pore pressure from 49 to 0.1 MPa and then increasing to 49 MPa. While Vp/Vs for the intact specimen is almost constant at elevated pore pressure, the Vp/Vs values for the thermally cracked ones were 2.0~2.2 when pore pressure was larger than 30 MPa. In future, we will reveal the relationship between the measured elastic wave velocities and the characteristics of the microfracture distribution. This work was supported by JSPS Grant-in-Aid for Scientific Research (Grant Number 26400492).

  19. Influence of cortical canal architecture on lacunocanalicular pore pressure and fluid flow.

    PubMed

    Goulet, G C; Cooper, D M L; Coombe, D; Zernicke, R F

    2008-08-01

    Bone is a dynamic tissue that undergoes structural modification in response to its mechanical environment, but how bone cells sense and respond to loading conditions remains incompletely understood. Current theories focus on strain-induced fluid flow for the primary means of mechanotransduction. To examine the influence of age-related cortical rarefaction on lacunocanalicular fluid characteristics, coupled fluid flow and mechanical computational models of bone specimens representing young, mid-age and aged samples were derived artificially from the same original micro-computed tomography image data. Simulated mechanical loading was applied to the bone models to induce pressure-driven interstitial fluid flow. Results demonstrated a decrease in pore pressure and fluid velocity magnitudes with age as a result of increased cortical porosity. Mean canal separation, as opposed to canal size, was implicated as a primary factor affecting age-related fluid dynamics. Future investigations through refinement of the model may implicate fluid stasis or inadequate nutrient transport experienced by osteocytes as a key factor in the initiation of cortical remodelling events.

  20. Copper Nanowire-Based Aerogel with Tunable Pore Structure and Its Application as Flexible Pressure Sensor.

    PubMed

    Xu, Xiaojuan; Wang, Ranran; Nie, Pu; Cheng, Yin; Lu, Xiaoyu; Shi, Liangjing; Sun, Jing

    2017-04-26

    Aerogel is a kind of material with high porosity and low density. However, the research on metal-based aerogel with good conductivity is quite limited, which hinders its usage in electronic devices, such as flexible pressure sensors. In this work, we successfully fabricate copper nanowire (CuNW) based aerogel through a one-pot method, and the dynamics for the assembly of CuNWs into hydrogel is intensively investigated. The "bubble controlled assembly" mechanism is put forward for the first time, according to which tunable pore structures and densities (4.3-7.5 mg cm(-3)) of the nanowire aerogel is achieved. Subsequently, ultralight flexible pressure sensors with tunable sensitivities (0.02 kPa(-1) to 0.7 kPa(-1)) are fabricated from the Cu NWs aerogels, and the negative correlation behavior of the sensitivity to the density of the aerogel sensors is disclosed systematically. This work provides a versatile strategy for the fabrication of nanowire-based aerogels, which greatly broadens their application potential.

  1. Exercise excess pressure and exercise-induced albuminuria in patients with type 2 diabetes mellitus.

    PubMed

    Climie, Rachel E D; Srikanth, Velandai; Keith, Laura J; Davies, Justin E; Sharman, James E

    2015-05-01

    Exercise-induced albuminuria is common in patients with type 2 diabetes mellitus (T2DM) in response to maximal exercise, but the response to light-moderate exercise is unclear. Patients with T2DM have abnormal central hemodynamics and greater propensity for exercise hypertension. This study sought to determine the relationship between light-moderate exercise central hemodynamics (including aortic reservoir and excess pressure) and exercise-induced albuminuria. Thirty-nine T2DM (62 ± 9 yr; 49% male) and 39 nondiabetic controls (53 ± 9 yr; 51% male) were examined at rest and during 20 min of light-moderate cycle exercise (30 W; 50 revolutions/min). Albuminuria was assessed by the albumin-creatinine ratio (ACR) at rest and 30 min postexercise. Hemodynamics recorded included brachial and central blood pressure (BP), aortic stiffness, augmented pressure (AP), aortic reservoir pressure, and excess pressure integral (Pexcess). There was no difference in ACR between groups before exercise (P > 0.05). Exercise induced a significant rise in ACR in T2DM but not controls (1.73 ± 1.43 vs. 0.53 ± 1.0 mg/mol, P = 0.002). All central hemodynamic variables were significantly higher during exercise in T2DM (i.e., Pexcess, systolic BP and AP; P < 0.01 all). In T2DM (but not controls), exercise Pexcess was associated with postexercise ACR (r = 0.51, P = 0.002), and this relationship was independent of age, sex, body mass index, heart rate, aortic stiffness, antihypertensive medication, and ambulatory daytime systolic BP (β = 0.003, P = 0.003). Light-moderate exercise induced a significant rise in ACR in T2DM, and this was independently associated with Pexcess, a potential marker of vascular dysfunction. These novel findings suggest that Pexcess could be important for appropriate renal function in T2DM.

  2. Relationships between sleep-disordered breathing and blood pressure and excessive daytime sleepiness among truck drivers.

    PubMed

    Cui, Renzhe; Tanigawa, Takeshi; Sakurai, Susumu; Yamagishi, Kazumasa; Iso, Hiroyasu

    2006-08-01

    Sleep-disordered breathing is a risk factor for hypertension, cardiovascular disease and accidents in the general population, but little is known about this correlation among professional truck drivers. To examine the relationships of sleep-disordered breathing with blood pressure levels and excessive daytime sleepiness among truck drivers, we conducted a population-based cross-sectional study of 1,313 subjects aged 20-69 years registered in the Japanese Trucking Association. The 3% oxygen desaturation index was selected as an indicator of sleep-disordered breathing, representing the number of desaturation events per hour of recording time in which blood oxygen fell by > or = 3% by overnight pulse oximetry. The Epworth Sleepiness Scale was used to estimate excessive daytime sleepiness. There were significant positive associations between the 3% oxygen desaturation index levels and both diastolic blood pressure levels and Epworth Sleepiness Scale scores. The multivariate odds ratio of hypertension was 2.0 (1.1-3.6) for a 3% oxygen desaturation index of > or = 15 in reference with a 3% oxygen desaturation index of <5. This association was more evident among those aged > or = 40 years and overweight subjects. Further, the multivariate odds ratio of an Epworth Sleepiness Scale of > or = 11 was 2.3 (1.1-4.9) for a 3% oxygen desaturation index of > or =15 in reference with a 3% oxygen desaturation index of <5. This association was more evident among those aged > or =40 years. The associations of sleep-disordered breathing severity with diastolic blood pressure levels and excessive daytime sleepiness suggest the need for sleep-disordered breathing screening among truck drivers for prevention of hypertension and potential traffic accidents.

  3. Observations of wave-induced pore pressure gradients and bed level response on a surf zone sandbar

    NASA Astrophysics Data System (ADS)

    Anderson, Dylan; Cox, Dan; Mieras, Ryan; Puleo, Jack A.; Hsu, Tian-Jian

    2017-06-01

    Horizontal and vertical pressure gradients may be important physical mechanisms contributing to onshore sediment transport beneath steep, near-breaking waves in the surf zone. A barred beach was constructed in a large-scale laboratory wave flume with a fixed profile containing a mobile sediment layer on the crest of the sandbar. Horizontal and vertical pore pressure gradients were obtained by finite differences of measurements from an array of pressure transducers buried within the upper several centimeters of the bed. Colocated observations of erosion depth were made during asymmetric wave trials with wave heights between 0.10 and 0.98 m, consistently resulting in onshore sheet flow sediment transport. The pore pressure gradient vector within the bed exhibited temporal rotations during each wave cycle, directed predominantly upward under the trough and then rapidly rotating onshore and downward as the wavefront passed. The magnitude of the pore pressure gradient during each phase of rotation was correlated with local wave steepness and relative depth. Momentary bed failures as deep as 20 grain diameters were coincident with sharp increases in the onshore-directed pore pressure gradients, but occurred at horizontal pressure gradients less than theoretical critical values for initiation of the motion for compact beds. An expression combining the effects of both horizontal and vertical pore pressure gradients with bed shear stress and soil stability is used to determine that failure of the bed is initiated at nonnegligible values of both forces.Plain Language SummaryThe <span class="hlt">pressure</span> gradient present within the seabed beneath breaking waves may be an important physical mechanism transporting sediment. A large-scale laboratory was used to replicate realistic surfzone conditions in controlled tests, allowing for horizontal and vertical <span class="hlt">pressure</span> gradient magnitudes and the resulting sediment bed response to be observed with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMOS11A1104F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMOS11A1104F"><span>Forward modeling <span class="hlt">pore</span> <span class="hlt">pressure</span> evolution in the Ursa Basin, offshore Louisiana, Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flemings, P. B.; You, Y.; Sawyer, D.; Schneider, J.</p> <p>2008-12-01</p> <p>We simulate deposition, <span class="hlt">pore</span> <span class="hlt">pressure</span> evolution, and flow in sediments of the Ursa Basin, Gulf of Mexico since 200 ka. These strata are composed of four successive depositional units: hemipelagic mudstone, the Blue Unit basin-floor fan, channel-levee deposition, and distal fan deposits. The Blue Unit, a laterally continuous, horizontal, sand-rich body overlies the hemipelagic mudstone. Channel-levee sediments buried the Blue Unit asymmetrically: its western margin (Site U1324) is 600 meters thick whereas its eastern margin (Site U1322) is only 230 meters thick. The base of the Blue Unit is dated at approximately 70ka and mudstones 20 meters above the Blue Unit are dated at 57 ky. Permeability is assumed to vary exponentially with porosity (log (k) = γφ +k0, where k is vertical permeability (m2), φ is porosity, and γ and k0 are fitting parameters). For clayey silts γ is 9.19 and k0 is -19.77, whereas for silty clays γ is 9.17 and k0 is -21.67. Compression is described as an exponential function of effective stress: e = -B/A +(eo+ B/A)×(σvhA/ln(10). For the Ursa mudstones, A = 0.338 and B = 0.152, eo = 0.894. We find that the rapid sedimentation at Site U1324 (~12 mm/yr) generates severe overpressures λ* =0.6 (λ* = P*/σvh). , where P* is overpressure and σvh is the hydrostatic effective stress), whereas a lower sedimentation rate at Site 1322 (3 mm/yr) generates modest overpressure (λ* = 0.3). The degree of lateral flow within the Blue Unit is striking: immediately upon burial by overlying mudstone, it acts to completely focus flow from the thick overburden section (Site U1324) toward the thin overburden section (Site U1322). This results in significant elevation of <span class="hlt">pore</span> <span class="hlt">pressure</span> at Site U1322, the location of lowest overpressure and provides a mechanism for the large submarine landslides and low regional gradient (2 degrees) offshore from the Mississippi delta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.S44B..07G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.S44B..07G"><span>Slow slip pulses driven by thermal <span class="hlt">pressurization</span> of <span class="hlt">pore</span> fluid: theory and observational constraints</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garagash, D.</p> <p>2012-12-01</p> <p>We discuss recently developed solutions for steadily propagating self-healing slip pulses driven by thermal <span class="hlt">pressurization</span> (TP) of <span class="hlt">pore</span> fluid [Garagash, 2012] on a fault with a constant sliding friction. These pulses are characterized by initial stage of undrained weakening of the fault (when fluid/heat can not yet escape the frictionally heated shear zone), which gives way to partial restrengthening due to increasing hydrothermal diffusion under conditions of diminished rate of heating, leading to eventual locking of the slip. The rupture speed of these pulses is decreasing function of the thickness (h) of the principal shear zone. We find that "thick" shear zones, h >> hdyna, where hdyna = (μ/τ0) (ρc/fΛ)(4α/cs), can support aseismic TP pulses propagating at a fraction hdyna/h of the shear wave speed cs, while "thin" shear zones, h˜hdyna or thinner, can only harbor seismic slip. (Here μ - shear modulus, τ0 - the nominal fault strength, f - sliding friction, ρc - the heat capacity of the fault gouge, Λ - the fluid thermal <span class="hlt">pressurization</span> factor, α - hydrothermal diffusivity parameter of the gouge). For plausible range of fault parameters, hdyna is between 10s to 100s of micrometers, suggesting that slow slip transients propagating at 1 to 10 km/day may occur in the form of a TP slip pulse accommodated by a meter-thick shear zone. We verify that this is, indeed, a possibility by contrasting the predictions for aseismic, small-slip TP pulses operating at seismologically-constrained, near-lithostatic <span class="hlt">pore</span> <span class="hlt">pressure</span> (effective normal stress ≈ 3 to 10 MPa) with the observations (slip duration at a given fault location ≈ week, propagation speed ≈ 15 km/day, and the inferred total slip ≈ 2 to 3 cm) for along-strike propagation of the North Cascadia slow slip events of '98-99 [Dragert et al., 2001, 2004]. Furthermore, we show that the effect of thermal <span class="hlt">pressurization</span> on the strength of the subduction interface is comparable to or exceeds that of the rate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22004050','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22004050"><span>Laser-Doppler acoustic probing of granular media with in-depth property gradient and varying <span class="hlt">pore</span> <span class="hlt">pressures</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bodet, L.; Dhemaied, A.; Mourgues, R.; Tournat, V.; Rejiba, F.</p> <p>2012-05-24</p> <p>Non-contacting ultrasonic techniques recently proved to be efficient in the physical modeling of seismic-wave propagation at various application scales, as for instance in the context of geological analogue and seismic modeling. An innovative experimental set-up is proposed here to perform laser-Doppler acoustic probing of unconsolidated granular media with varying <span class="hlt">pore</span> <span class="hlt">pressures</span>. The preliminary experiments presented here provide reproducible results and exploitable data, thus validating both the proposed medium preparation and <span class="hlt">pressure</span> gradient generation procedure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T13E..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T13E..03P"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> evolution and induced seismicity within the Permian Basin, Southeast New Mexico USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Person, M. A.; Zhang, Y.; Mozley, P.; Broadhead, R.; Bilek, S.; Edel, S.</p> <p>2015-12-01</p> <p>We used three-dimensional hydrologic modeling to assess the potential linkages between crystalline basement seismicity (up to M3.2) beneath the Dagger Draw oil field in response to saline water reinjection. Production began in 2004 and preceded an increase in seismicity by about 5 years. Reinjection of produced brines occurred within the basal Ellenberger Group carbonate reservoir (yellow square). Published core permeability measurements for the Ellenberger vary between about 10-15 to 10-12 m2. Evidence for seismicity being triggered by injection include observations that the largest injection rates (> 106 barrels/month) occurred within wells closest to the induced seismicity (red circle about 15 km to the west of the injection well in A-C). Arguing against triggered seismicity is the apparent lack of temporal correlation between peak injection and felt seismicity as well as the extreme depth of the earthquakes (about 10-12 km below land surface). We conducted a numerical sensitivity study in which we varied the permeability of the basal reservoir as well as the crystalline basement rocks over several orders of magnitude. Assuming a crystalline basement permeability of 10-16 m2 and a basal reservoir permeability of 10-13 m2 produced about 50 m of <span class="hlt">excess</span> heads in the seismogenic crust about 1900 days (D) after injection started. Prior studies suggest that <span class="hlt">excess</span> heads of only a few meters could induce failure along critically stressed faults. The lag between injection and seismicity can be explained by the time required for the <span class="hlt">pressure</span> envelope to propagate laterally 15 km and downward into the crystalline basement 11 km. Peak injection occurred 1900 days before recent increases in seismicity were observed. Future work will include assessing the potential role of relatively permeable Proterozoic faults in transmitting high fluid <span class="hlt">pressures</span> into the crystalline basement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4028949','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4028949"><span><span class="hlt">Excess</span> Weight, Anthropometric Variables and Blood <span class="hlt">Pressure</span> in Schoolchildren aged 10 to 18 years</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schommer, Vânia Ames; Barbiero, Sandra Mari; Cesa, Cláudia Ciceri; Oliveira, Rosemary; Silva, Anelise Damiani; Pellanda, Lucia Campos</p> <p>2014-01-01</p> <p>Background The prevalence of hypertension among children and adolescents is estimated to range between 1% and 13%. <span class="hlt">Excess</span> weight and central obesity are related to blood <span class="hlt">pressure</span> levels in adults, and may be important in the early pathogenesis of SH when present in childhood. Objectives To study the association between anthropometric variables and blood <span class="hlt">pressure</span> levels in schoolchildren from the 5th and 8th grades, and to identify which parameter was more strongly correlated with blood <span class="hlt">pressure</span> levels. Methods Contemporary cross-sectional study with probabilistic population-based cluster sampling of schoolchildren enrolled from the 5th to the 8th grades in public elementary schools of Porto Alegre. Data on familial risk factors and anthropometry were collected. Statistical analysis included correlations and cluster-adjusted confidence intervals. Results The mean age of participants was 12.57 (± 1.64) years, and 55.2% of them were females. Abnormal blood <span class="hlt">pressure</span> levels were found in 11.3% of the sample and borderline values, in 16.2%. Among the anthropometric variables analyzed, hip circumference was the one with the strongest correlation with increased blood <span class="hlt">pressure</span> (r = 0.462, p < 0.001), followed by waist circumference (r = 0.404, p < 0.001) and abdominal skinfold (r = 0.291, p < 0.001). Conclusion We observed an association of waist circumference and skinfolds with increased blood <span class="hlt">pressure</span> levels in the schoolchildren of the sample. Therefore, it is of the utmost importance that early measurements of blood <span class="hlt">pressure</span>, and waist and hip circumferences become a routine in health services in order to prevent this condition. PMID:24676224</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V41D..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V41D..02S"><span>The signature of devolatisation: <span class="hlt">excess</span> 40Ar in high <span class="hlt">pressure</span> rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smye, A.; Warren, C. J.; Bickle, M. J.; Holland, T.</p> <p>2012-12-01</p> <p>The presence of <span class="hlt">excess</span> 40Ar in (ultra-)high <span class="hlt">pressure</span> ((U)HP) metamorphic rocks shows that the assumption of open system argon exchange between the source mineral and the grain boundary is not valid. Typically, phengites from (U)HP metasediments have apparent 40Ar/39Ar ages <50% in <span class="hlt">excess</span> of the age of peak (U)HP conditions, whereas cogenetic mafic eclogites yield ages up to 700% older, despite lower bulk-rock K2O concentrations. Given the highly incompatible behaviour of argon, the fraction of protolith-derived 40Ar that is retained by mica on equilibration under (U)HP conditions reflects the extent to which the rock has behaved as an open or closed system to volatile-loss during subduction. This has not previously been quantified for (U)HP rocks. A model is developed that calculates <span class="hlt">excess</span> argon age fractions as a function of variable mica—fluid KD, bulk K2O and porosity under closed system conditions. Using two recently-published single-grain 40Ar/39Ar datasets from the Tauern Window [1] and Omani [2] HP terranes, measured <span class="hlt">excess</span> argon concentrations in mafic eclogites are reproduced only when porosities are <10-4 volume fraction, showing that mafic protoliths operate as closed systems to advective solute transport during subduction. Porosities in eclogite-facies metapelites are >10-3, reflecting loss of significant volumes of lattice-bound H2O relative to mafic rocks during subduction. These results are supported by phase equilibria calculations of H2O loss during progade metamorphism of a MORB and pelitic rock composition: pelites lose H2O continuously along subduction geotherms, whereas MORB compositions require hydration, or, liberate small quantities of structurally bound H2O. Violation of the model assumptions by loss of argon, or transiently higher porosities will lower the <span class="hlt">excess</span> argon age. Accordingly, the porosity estimates provide a limiting case to examine the effects of fluid availability, permeability and argon diffusivity on the accumulation of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987tasi.conf.....S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987tasi.conf.....S"><span><span class="hlt">Excess</span> thermodynamic properties of aqueous electrolytes to high temperatures and <span class="hlt">pressures</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simonson, J. M.; Holmes, H. F.; Mesmer, R. E.; Busey, R. H.</p> <p></p> <p><span class="hlt">Excess</span> thermodynamic properties have been obtained for a number of pure and mixed aqueous electrolyte solutions at high temperatures and <span class="hlt">pressures</span> through measurements of isopiestic ratios and enthalpies of dilution. The equipment and techniques used are described. Representations of the results used to correlate measured values and calculate other thermodynamic quantities are described. Isopiestic ratios relative to NaCl(aq) standard solutions have been measured for a number of classes of electrolytes to 250 C, including the alkali and alkaline earth chlorides, alkali sulfates and bisulfates, and a number of mixed electrolyte solutions. Flow calorimetric measurements of dilution enthalpies have been made as functions of temperature and <span class="hlt">pressure</span> to 400 C and 400 bars on NaCl(aq), CaCl2(aq) and NaOH(aq). Results extend across the temperature range of transition between strong electrolyte behavior, as indicated by results at low temperatures, and ion association at high temperatures, as has been indicated in studies of electrical conductance. Modeling of the experimental results with other available data has given consistent sets of values of <span class="hlt">excess</span> thermodynamic properties for a number of aqueous electrolyte systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/15001675','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/15001675"><span>Characterization of <span class="hlt">pore</span> structure and hydraulic property alteration in <span class="hlt">pressurized</span> unsaturated flow tests</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McGrail, B. Peter; Lindenmeier, Clark W.; Martin, P F.</p> <p>1999-12-01</p> <p>The <span class="hlt">pressurized</span> unsaturated flow (PUF) test is a new experimental method for the evaluation of the long-term corrosion behavior of waste forms and other engineered barrier materials. Essentially, the technique provides a means to flow water through a porous bed of test material or materials at elevated temperature and under hydraulically unsaturated conditions. Bulk volumetric content, effluent pH and electrical conductivity are monitored in real time using a computer control and data acquisition system. In previous papers, we have reported on the changes in bulk water content, effluent chemistry, and glass corrosion rates that result from the formation of alteration products during these tests. These measurements are now supplemented through the use of the ultracentrifugation apparatus (UFA) for hydraulic property measurements and high-resolution, x-ray microtomography (XMT) to provide 3-D spatial and temporal imaging of water distribution and <span class="hlt">pore</span> structure alteration during these tests. Quantitative changes in the water retention characteristic were correlated with the onset of zeolite formation in the tests. Extensive alteration of the glass resulted in cementation of the glass grains near the bottom of the column, which was observed in situ using the XMT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20015787','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20015787"><span>Characterization of <span class="hlt">pore</span> structure and hydraulic property alteration in <span class="hlt">pressurized</span> unsaturated flow tests</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McGrail, B.P.; Lindenmeier, C.W.; Martin, P.F.</p> <p>1999-07-01</p> <p>The <span class="hlt">pressurized</span> unsaturated flow (PUF) test is a new experimental method for the evaluation of the long-term corrosion behavior of waste forms and other engineered barrier materials. Essentially, the technique provides a means to flow water through a porous bed of test material or materials at elevated temperature and under hydraulically unsaturated conditions. Bulk volumetric content, effluent pH and electrical conductivity are monitored in real time using a computer control and data acquisition system. In previous papers, the authors have reported on the changes in bulk water content, effluent chemistry, and glass corrosion rates that result from the formation of alteration products during these tests. These measurements are now supplemented through the use of the ultracentrifugation apparatus (UFA) for hydraulic property measurements and high-resolution, x-ray microtomography (XMT) to provide 3-D spatial and temporal imaging of water distribution and <span class="hlt">pore</span> structure alteration during these tests. Quantitative changes in the water retention characteristic were correlated with the onset of zeolite formation in the tests. Extensive alteration of the glass resulted in cementation of the glass grains near the bottom of the column, which was observed in situ using the XMT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.G51A0940B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.G51A0940B"><span>A Mechanism for Seismically Induced <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Changes Inferred from High Frequency Water Well Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.</p> <p>2002-12-01</p> <p>Earthquakes can produce water level changes in certain distant wells orders of magnitude larger than can be explained by static stress changes. The redistribution of <span class="hlt">pore</span> <span class="hlt">pressure</span> can generate crustal deformation and perhaps even trigger seismicity. Some studies suggest that earthquakes induce permeability increases or other aquifer property changes. Standard hydrogeological methods do not continuously measure aquifer properties therefore it is difficult to monitor the inferred variations. We developed a new method to measure aquifer properties over short times by combining high-sample rate water level data (1 sps) and seismic data for a site near Grants Pass Oregon. The new method motivates a new model in which the seismic waves remove transient barriers of sediment in a fracture. Pumping test data for the site is well-modeled by a single, infinitesimally thin square planar fracture embedded in a unbounded, homogeneous and isotropic confined aquifer. For this geometry, the amplification factor χ, defined as the ratio of the water level amplitude to the ground velocity, as a function of frequency f is \\[ χ = A(\</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011RMRE...44..541R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011RMRE...44..541R"><span>Analysis of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Stress Distribution around a Wellbore Drilled in Chemically Active Elastoplastic Formations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roshan, Hamid; Rahman, S. S.</p> <p>2011-09-01</p> <p>Drilling in low-permeable reactive shale formations with water-based drilling mud presents significant challenges, particularly in high-<span class="hlt">pressure</span> and high-temperature environments. In previous studies, several models were proposed to describe the thermodynamic behaviour of shale. Most shale formations under high <span class="hlt">pressure</span> are expected to undergo plastic deformation. An innovative algorithm including work hardening is proposed in the framework of thermo-chemo-poroelasticity to investigate the effect of plasticity on stresses around the wellbore. For this purpose a finite-element model of coupled thermo-chemo-poro-elastoplasticity is developed. The governing equations are based on the concept of thermodynamics of irreversible processes in discontinuous systems. In order to solve the plastic problem, a single-step backward Euler algorithm containing a yield surface-correction scheme is used to integrate the plastic stress-strain relation. An initial stress method is employed to solve the non-linearity of the plastic equation. In addition, super convergent patch recovery is used to accurately evaluate the time-dependent stress tensor from nodal displacement. The results of this study reveal that thermal and chemical osmosis can significantly affect the fluid flow in low-permeable shale formations. When the salinity of drilling mud is higher than that of <span class="hlt">pore</span> fluid, fluid is pulled out of the formation by chemical osmotic back flow. Similar results are observed when the temperature of drilling mud is lower than that of the formation fluid. It is found that linear elastic approaches to wellbore stability analysis appear to overestimate the tangential stress around the wellbore and produce more conservative stresses compared to the results of field observation. Therefore, the drilling mud properties obtained from the elastoplastic wellbore stability in shales provide a safer mud weight window and reduce drilling cost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24199602','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24199602"><span>Effects of setting under air <span class="hlt">pressure</span> on the number of surface <span class="hlt">pores</span> and irregularities of dental investment materials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tourah, Anita; Moshaverinia, Alireza; Chee, Winston W</p> <p>2014-02-01</p> <p>Surface roughness and irregularities are important properties of dental investment materials that can affect the fit of a restoration. Whether setting under air <span class="hlt">pressure</span> affects the surface irregularities of gypsum-bonded and phosphate-bonded investment materials is unknown. The purpose of this study was to investigate the effect of air <span class="hlt">pressure</span> on the <span class="hlt">pore</span> size and surface irregularities of investment materials immediately after pouring. Three dental investments, 1 gypsum-bonded investment and 2 phosphate-bonded investments, were investigated. They were vacuum mixed according to the manufacturers' recommendations, then poured into a ringless casting system. The prepared specimens were divided into 2 groups: 1 bench setting and the other placed in a <span class="hlt">pressure</span> pot at 172 kPa. After 45 minutes of setting, the rings were removed and the investments were cut at a right angle to the long axis with a diamond disk. The surfaces of the investments were steam cleaned, dried with an air spray, and observed with a stereomicroscope. A profilometer was used to evaluate the surface roughness (μm) of the castings. The number of surface <span class="hlt">pores</span> was counted for 8 specimens from each group and the means and standard deviations were reported. Two-way ANOVA was used to compare the data. Specimens that set under atmospheric air <span class="hlt">pressure</span> had a significantly higher number of <span class="hlt">pores</span> than specimens that set under increased <span class="hlt">pressure</span> (P<.05). No statistically significant differences for surface roughness were found (P=.078). Also, no significant difference was observed among the 3 different types of materials tested (P>.05). Specimens set under positive <span class="hlt">pressure</span> in a <span class="hlt">pressure</span> chamber presented fewer surface bubbles than specimens set under atmospheric <span class="hlt">pressure</span>. Positive <span class="hlt">pressure</span> is effective and, therefore, is recommended for both gypsum-bonded and phosphate-bonded investment materials. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21688551','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21688551"><span>[Current research of the <span class="hlt">excessive</span> lateral <span class="hlt">pressure</span> syndrome of patellofemoral joint].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jin-song; Zhang, Dao-ping</p> <p>2011-05-01</p> <p>As modern medicine getting deeply to understand ever-detailed anatomy,structure and animal mechanics of the patellofemoral joint, <span class="hlt">excessive</span> lateral <span class="hlt">pressure</span> syndrome, a very common patellofemoral disorder, has been reacquainted by the clinicians. On account to the complexity and variety of the etiology and the mechanism of the pain, still, there are many difficulties and arguments on the exact description of the clinical symptoms and the establishment of a universally accepted diagnostic criteria. Accurately grasping different causes, pathomechanisms and developmental stages of the disease would be especially important. As a result, rational choice of the pertinent procedures become the clinical lynchpin. This paper reviews domestic and international pertinent literatures in the past 10 years, and provide an overview of the latest study of anatomy, biomechanic, pathomechanism and clinical experience, anticipating to offer help on standardizing the diagnosis and treatment of ELPS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR13A2242H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR13A2242H"><span>Influence of <span class="hlt">Pore</span>-Fluid <span class="hlt">Pressure</span> on Elastic Wave Velocity and Electrical Conductivity in Water-Saturated Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Higuchi, A.; Watanabe, T.</p> <p>2013-12-01</p> <p><span class="hlt">Pore</span>-fluid <span class="hlt">pressure</span> in seismogenic zones can play a key role in the occurrence of earthquakes (e.g., Sibson, 2009). Its evaluation via geophysical observations can lead to a good understanding of seismic activities. The evaluation requires a thorough understanding of the influence of the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> on geophysical observables like seismic velocity and electrical conductivity. We have studied the influence of <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> on elastic wave velocity and electrical conductivity in water-saturated rocks. Fine grained (100-500μm) biotite granite (Aji, Kagawa pref., Japan) was used as rock samples. The density is 2.658-2.668 g/cm3, and the porosity 0.68-0.87%. The sample is composed of 52.8% plagioclase, 36.0% Quartz, 3.0% K-feldspar, 8.2% biotite. SEM images show that a lot of grain boundaries are open. Few intracrystalline cracks were observed. Following the method proposed by David and Zimmerman (2012), the distribution function of crack aspect ratio was evaluated from the <span class="hlt">pressure</span> dependence of compressional and shear wave velocities in a dry sample. Cylindrical sample has dimensions of 25 mm in diameter and 30 mm in length, and saturated with 0.01 mol/l KCl aqueous solution. Compressional and shear wave velocities were measured with the pulse transmission technique (PZT transducers, f=2 MHz), and electrical conductivity the two-electrode method (Ag-AgCl electrodes, f=1 Hz-100 kHz). Simultaneous measurements of velocities and conductivity were made using a 200 MPa hydrostatic <span class="hlt">pressure</span> vessel, in which confining and <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> can be separately controlled. The <span class="hlt">pore</span>-fluid is electrically insulated from the metal work of the <span class="hlt">pressure</span> vessel by using a newly designed plastic device (Watanabe and Higuchi, 2013). The confining <span class="hlt">pressure</span> was progressively increased up to 25 MPa, while the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> was kept at 0.1 MPa. It took five days or longer for the electrical conductivity to become stationary after increasing the confining <span class="hlt">pressure</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/665933','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/665933"><span>[Investigation of high <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> in the Uinta Basin, Utah]. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>1998-11-01</p> <p>High <span class="hlt">pore</span> fluid <span class="hlt">pressures</span>, approaching lithostatic, are observed in the deepest sections of the Uinta basin, Utah. The authors analyzed the cause of the anomalous overpressures with a 3-dimensional, numerical model of the evolution of the basin, including compaction disequilibrium and hydrocarbon generation as possible mechanisms. The numerical model builds the basin through time, coupling the structural, thermal and hydrodynamic evolution, and includes in situ hydrocarbon generation and migration. They used the evolution model to evaluate overpressure mechanisms and oil migration patterns for different possible conceptual models of the geologic history. Model results suggest that observed overpressures in the Uinta basin are probably caused by ongoing oil generation in strata with specific conditions of permeability, relative permeability, TOC content, and oil viscosity. They conducted a sensitivity analysis that suggests for oil generation to cause overpressures, the necessary conditions are: oil viscosity is {approximately}0.05 cP or higher, intrinsic permeability is {approximately}5 {times} 10{sup {minus}18} m{sup 2} or lower, and source rock TOC values are {approximately}0.5% or higher. The authors also analyzed hydrocarbon migration patterns in the basin and how they are affected by the basin`s structural history. Oil migration patterns produced by the model are consistent with published oil production maps: oil moves from the deep Altamont source rocks toward Redwash, the eastern Douglas Creek Arch area, and southward towards the Sunnyside tar-sands and Book Cliffs. Peak oil generation occurs from the time of maximum burial in the mid-Tertiary ({approximately}35 to {approximately}30 Ma). Most differential uplift of the basin`s flanks probably occurs well after this time, and most oil migration to the basin`s southern and eastern flanks occurs prior to uplift of these flanks. Model results show that if the basin`s flanks are uplifted too soon, reduced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1713234S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1713234S"><span>Modeling the space-time evolution of <span class="hlt">pore</span> <span class="hlt">pressure</span> in layered shallow covers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salciarini, Diana; Cuomo, Sabatino; Castorino, Giuseppe; Fanelli, Giulia; Tamagnini, Claudio</p> <p>2015-04-01</p> <p>In most of the available models for the prediction of shallow landslide susceptibility, the potentially unstable soil cover is considered uniform and homogeneous, over an impervious underlying bedrock (see, e.g., Baum et al. 2008; Salciarini et al. 2006, 2012). However, in several case studies, this was proven to be unlikely, for example in the case of pyroclastic soil covers, where two clearly separated layers are detectable (Cascini et al., 2008, 2011). The possibility of taking into account the detailed configuration of the soil cover allows having a more accurate estimate of the potentially unstable volumes, which significantly modify the intensity of the considered phenomena. To take into account the possibility of having layers in the soil cover with different permeability, the existing routines of the TRIGRS code (Baum et al. 2008) devoted to the hydrologic process modeling have been modified. The closed-form solution by Srivastava & Yeh (1991) implemented into TRIGRS was substituted with the numerical solution of the mass balance equation governing the infiltration process. A parametric analysis was carried out by varying the permeability ratio between the two layers, with the aim of examining the influence of such parameter on the <span class="hlt">pore-pressure</span> distribution along the vertical profile. As expected, as the permeability ratio increases, the underlying layer tends to behave as an impervious boundary. This increases the chance that only the most superficial soil layer fails. An analysis of the routine performance and efficiency was also done to investigate the response of the model with different tolerances and different time steps of the integration procedure, and different spatial discretizations along the vertical profile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T52B..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T52B..05K"><span>Frictional Shear Stress, <span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span> and Wedge Mechanics on the Cascadia Megathrust Timothy Kane, Chris Goldfinger and Chris Romsos</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kane, T.; Goldfinger, C.; Romsos, C.</p> <p>2013-12-01</p> <p>Although Cascadia is one of the most studied subduction zones in the world, the mechanics of the seismogenic zone remain shrouded by a lack of offshore data quantifying both inter-seismic and co-seismic behavior. We use an analysis of accretionary wedge morphology and overburden-defined frictional shear stress to constrain the range of <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> suggested by seismic and geological observations. We also compare this result to the location of the down-dip maximum of inter-plate coupling as inferred from current geodetic and paleoseismic models of the locked zone. Using a new 100m bathymetric mosaic, McCrory et al.'s 2004 model of slab depth, a matrix of typical values for basal <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> (70-95% of lithostatic) and rock density (2300-2500 kg/m3), and assuming Byerlee's Law, where μb (coefficient of basal friction) = 0.85, to be valid on the decollement, shear traction on the Cascadia megathust was calculated from the deformation front east to the 450 degree basal isotherm as defined by Spinelli, 2012. On the basis of heat flow and thermal modeling, megathrusts worldwide are predicted to have an average maximum shear stress of 15MPa. Employing <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> above hydrostatic but well below lithostatic (λb = 0.7 - 0.86), our analysis resulted in frictional shear stress on the Cascadia megathrust meeting or exceeding 15MPa within 5-10 km of the deformation front, failing to satisfy the upper-slope to outer-shelf location of the down-dip limit of the locked zone and maximum inter-plate coupling as determined by current geodetic models. Basal <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> of at least 90% of lithostatic are required over the entire seismogenic zone to satisfy the proposed down-dip limit of the locked zone. This supports high <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> in the accretionary wedge, particularly in Washington, as suggested by the presence of landward-vergent thrusts, listric normal faults and near surface methane horizons in recent multi-channel seismic data</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JSG....69..465C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JSG....69..465C"><span>Predicting <span class="hlt">pore</span> <span class="hlt">pressure</span> in active fold-thrust systems: An empirical model for the deepwater Sabah foldbelt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Couzens-Schultz, Brent A.; Azbel, Konstantin</p> <p>2014-12-01</p> <p>Measurements related to mudrock (shale and siltstone) porosity such as acoustic velocity, density or electrical resistivity, have traditionally been used to predict <span class="hlt">pore</span> <span class="hlt">pressures</span> in extensional stress settings. The underlying assumption is that burial and vertical effective stress (VES), which is the overburden minus the <span class="hlt">pore</span> <span class="hlt">pressure</span>, controls the compaction of these rocks through porosity loss. The dataset presented here compares VES and acoustic velocity of similar composition mudrocks in both an extensional and a compressional stress setting. In the extensional stress environment, the mudrocks follow a typical compaction trend with a porosity loss and increase in acoustic velocity that can be related to VES. In an active fold-thrust belt, the compressive stresses further reduce the porosity and increase the acoustic velocity of the mudrocks. First a layer-parallel shortening compacts sediments beyond what is observed for the VES. This additional compaction is further enhanced near thrust faults and in anticlinal forelimbs, presumably due to additional shear stress in these areas. The mudrocks located in folds that are buried by additional sedimentation do not compact again until the tectonic compaction is overridden by enough new burial. After that, the mudrocks follow the observed extensional setting compaction trend. In the fold-thrust belt, the observed reduction in porosity by stresses other than burial leads to an under-prediction of <span class="hlt">pore</span> <span class="hlt">pressure</span> using traditional methods. To account for this, we present a correction that can be applied to the acoustic velocity (or porosity) using two parameters: (a) proximity to thrust faults and anticlinal forelimbs and (b) the amount of burial after fold formation. With these corrections, the extensional velocity-VES compaction trend can be used to accurately predict <span class="hlt">pore</span> <span class="hlt">pressure</span> within the active fold-thrust belt. The correction is calibrated with well data and is empirical. None-the-less, it is a first step toward</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017363','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017363"><span>Differential equations governing slip-induced <span class="hlt">pore-pressure</span> fluctuations in a water-saturated granular medium</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Iverson, R.M.</p> <p>1993-01-01</p> <p>Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic <span class="hlt">pore-pressure</span> fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and <span class="hlt">pore</span>-water <span class="hlt">pressures</span>. Solid displacements and water <span class="hlt">pressures</span> are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible <span class="hlt">pore</span> deformation that occurs along the bumpy slip surface. Feedback between this deformation and the <span class="hlt">pore-pressure</span> field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GGG....14.1454S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GGG....14.1454S"><span>In situ stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> in the Kumano Forearc Basin, offshore SW Honshu from downhole measurements during riser drilling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saffer, D. M.; Flemings, P. B.; Boutt, D.; Doan, M.-L.; Ito, T.; McNeill, L.; Byrne, T.; Conin, M.; Lin, W.; Kano, Y.; Araki, E.; Eguchi, N.; Toczko, S.</p> <p>2013-05-01</p> <p>situ stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> are key parameters governing rock deformation, yet direct measurements of these quantities are rare. During Integrated Ocean Drilling Program (IODP) Expedition #319, we drilled through a forearc basin at the Nankai subduction zone and into the underlying accretionary prism. We used the Modular Formation Dynamics Tester tool (MDT) for the first time in IODP to measure in situ minimum stress, <span class="hlt">pore</span> <span class="hlt">pressure</span>, and permeability at 11 depths between 729.9 and 1533.9 mbsf. Leak-off testing at 708.6 mbsf conducted as part of drilling operations provided a second measurement of minimum stress. The MDT campaign included nine single-probe (SP) tests to measure permeability and in situ <span class="hlt">pore</span> <span class="hlt">pressure</span> and two dual-packer (DP) tests to measure minimum principal stress. Permeabilities defined from the SP tests range from 6.53 × 10-17 to 4.23 × 10-14 m2. <span class="hlt">Pore</span> fluid <span class="hlt">pressures</span> are near hydrostatic throughout the section despite rapid sedimentation. This is consistent with the measured hydraulic diffusivity of the sediments and suggests that the forearc basin should not trap overpressures within the upper plate of the subduction zone. Minimum principal stresses are consistently lower than the vertical stress. We estimate the maximum horizontal stress from wellbore failures at the leak-off test and shallow MDT DP test depths. The results indicate a normal or strike-slip stress regime, consistent with the observation of abundant active normal faults in the seaward-most part of the basin, and a general decrease in fault activity in the vicinity of Site C0009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5435O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5435O"><span>Pre-drill <span class="hlt">Pore</span> <span class="hlt">pressure</span> estimation in shale gas reservoirs using seismic genetic inversion: Application to Barnett shale.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouadfeul, Sid-Ali; Aliouane, Leila; Eladj, Said</p> <p>2017-04-01</p> <p>In this paper, the seismic genetic inversion is used for estimation of the <span class="hlt">pore</span> <span class="hlt">pressure</span> before drilling, the first stage is to invert the 3D seismic cube recorded in the Fot Worth basin located in the United States of America using the artificial neural network. The Multilayer Perceptron neural network is trained in a supervised mode using the stacked 3D seismic amplitudes near three wells as an input and the calculated acoustic impedances derived from the density and sonic logs recorded in these wells as an output. During the training the weights of connections between neurons are optimized, then the whole seismic cube is propagated though the neural machine. The output of this machine is the cube of the acoustic impedance. A linear relationship between the depth and velocity are derived using sonic well-log data of a vertical well, this relationship will be us ed as a vertical trend in the Eaton's model. The acoustic impedances are used to deduce the <span class="hlt">pore</span> <span class="hlt">pressure</span> from the Eaton's model. The proposed process is applied to derive the <span class="hlt">pore</span> <span class="hlt">pressure</span> in the Lower Barnett shale, obtained results can be used for well-bore stability and hydraulic fracture planning and simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PApGe.174.2649C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PApGe.174.2649C"><span>Reduction of Injection-Induced <span class="hlt">Pore-Pressure</span> and Stress in Basement Rocks Due to Basal Sealing Layers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Kyung Won; Segall, Paul</p> <p>2017-07-01</p> <p>Our previous study (Chang and Segall, J Geophys Res Solid Earth 121(4):2708-2726, 2016a) demonstrated that diffusion of <span class="hlt">pore-pressure</span> and stress into basement rocks can cause slip on deep faults, potentially inducing seismicity. Recent studies suggest that the presence of a bottom-sealing layer between the injection horizon and basement will reduce the magnitude of injection-induced <span class="hlt">pore-pressure</span> in the basement due to contrasts in permeability and/or storage capacity. In this study, we examine the role of basal sealing horizons in induced seismicity on basement faults by adding a layer beneath the reservoir into the two-dimensional, fully coupled poroelastic model developed previously. We consider two types of basal seals: (1) a low-permeability seal and (2) a high-storativity seal. The analysis of the spatio-temporal change in Coulomb stress and time-dependent rate of earthquake nucleation confirms that both types of seal inhibit direct <span class="hlt">pore-pressure</span> diffusion into basement rocks, but poroelastic stresses are still transmitted, potentially inducing earthquakes. The high-storativity seal reduces the transmission of poroelastic stresses into the basement, minimizing seismicity on basement faults in comparison to the low-permeability seal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25449801','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25449801"><span>Ultrasound and microbubble mediated drug delivery: acoustic <span class="hlt">pressure</span> as determinant for uptake via membrane <span class="hlt">pores</span> or endocytosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>De Cock, Ine; Zagato, Elisa; Braeckmans, Kevin; Luan, Ying; de Jong, Nico; De Smedt, Stefaan C; Lentacker, Ine</p> <p>2015-01-10</p> <p>Although promising results are achieved in ultrasound mediated drug delivery, its underlying biophysical mechanisms remain to be elucidated. <span class="hlt">Pore</span> formation as well as endocytosis has been reported during ultrasound application. Due to the plethora of ultrasound settings used in literature, it is extremely difficult to draw conclusions on which mechanism is actually involved. To our knowledge, we are the first to show that acoustic <span class="hlt">pressure</span> influences which route of drug uptake is addressed, by inducing different microbubble-cell interactions. To investigate this, FITC-dextrans were used as model drugs and their uptake was analyzed by flow cytometry. In fluorescence intensity plots, two subpopulations arose in cells with FITC-dextran uptake after ultrasound application, corresponding to cells having either low or high uptake. Following separation of the subpopulations by FACS sorting, confocal images indicated that the low uptake population showed endocytic uptake. The high uptake population represented uptake via <span class="hlt">pores</span>. Moreover, the distribution of the subpopulations shifted to the high uptake population with increasing acoustic <span class="hlt">pressure</span>. Real-time confocal recordings during ultrasound revealed that membrane deformation by microbubbles may be the trigger for endocytosis via mechanostimulation of the cytoskeleton. <span class="hlt">Pore</span> formation was shown to be caused by microbubbles propelled towards the cell. These results provide a better insight in the role of acoustic <span class="hlt">pressure</span> in microbubble-cell interactions and the possible consequences for drug uptake. In addition, it pinpoints the need for a more rational, microbubble behavior based choice of acoustic parameters in ultrasound mediated drug delivery experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28947026','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28947026"><span>Manometry Optimized Positive Expiratory <span class="hlt">Pressure</span> (MOPEP) in <span class="hlt">Excessive</span> Dynamic Airway Collapse (EDAC).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zafar, Muhammad A; Mulhall, Aaron M; Eschenbacher, William; Kaul, Ajay; Benzaquen, Sadia; Panos, Ralph J</p> <p>2017-10-01</p> <p>Positive expiratory <span class="hlt">pressure</span>(PEP) breathing modalities are commonly prescribed in obstructive lung diseases, however practical methods of airway <span class="hlt">pressures</span>(AP) quantification for therapeutic efficacy are lacking. <span class="hlt">Excessive</span> dynamic airway collapse(EDAC) is characterized by expiratory central airway collapse leading to dyspnea and poor quality of life(QoL), with limited therapeutic options. To measure AP and exertional dyspnea in EDAC patients during normal breathing and with use of pursed-lip breathing(PLB), nasal PEP device(nPEP), and oral-PEP valve(oPEP) during rest and exercise using an Esophageal Manometer. EDAC patients exercised on a bicycle ergometer sequentially using normal breathing, PLB, nPEP, and oPEP for five-minute intervals. AP's were measured by continuous topographic upper airway manometry. Pre- and post-exercise BORG dyspnea scores were recorded and QoL measured with the St. George's respiratory questionnaire(SGRQ-C). The most effective and patient-preferred PEP modality was prescribed for daily activities and SGRQ-C repeated after one week. Three women with symptomatic EDAC participated. Expiratory laryngopharyngeal AP's during exercise with normal breathing, PLB, nPEP and oPEP in patient-1 were 1.7, 14, 4.5, and 7.3 mmHg, in patient-2; 2.3, 8, 8.3, and 12 mmHg, and in patient-3; 1, 15, unobtainable, and 9 mmHg, respectively. Maximal reduction in BORG scores occurred with PLB in patient 1 and with oPEP in patients 2 and 3. After 1 week mean SGRQ-C scores declined by 17-points. Upper airway manometry directly measures laryngopharyngeal <span class="hlt">pressures</span> during rest and exercise and can be used to select and optimize PEP breathing techniques to improve respiratory symptoms in EDAC patients. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.H51F0909M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.H51F0909M"><span>Using Seismic Reflection Data to Investigate Gas-generated <span class="hlt">Pore</span> <span class="hlt">Pressure</span> in a Landslide-prone Area: an Example From Finneidfjord, Norway</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morgan, E. C.; Vanneste, M.; Longva, O.; Lecomte, I.; McAdoo, B.; Baise, L.</p> <p>2008-12-01</p> <p>On the 20th of June, 1996, approximately 1 million cubic meters of soil failed in Finneidfjord, Norway. The multi-phase, retrogressive landslide initiated underwater, and, within a few hours, undermined a highway and several houses, claiming the lives of four people. The Finneidfjord location provides numerous geological and environmental conditions relevant for offshore geohazards and large-scale submarine landslides. Examples are slide-prone sedimentary layers, lateral and vertical lithological variability, the presence of slide blocks, gas-bearing sediments, and migration pathways, which could well indicate <span class="hlt">excess</span> <span class="hlt">pore</span> <span class="hlt">pressure</span>. Whereas several factors likely contributed to this slope failure, we focus on the role that free gas played in destabilizing the slope. In a core from near the slide area, gas bubbles appear in the X-ray as vesicular spots. High-resolution two-dimensional seismic profiles reveal the presence of a pronounced gas front as a distinct, polarity-reversed reflection that can be traced over an area of ~5 km2. The top of the gassy zone lies a few meters below the seabed (close to the suspected failure plane of the 1996 slide), and strongly attenuates the seismic reflection signal. We measure this attenuation by observing changes in the energy density with travel time; using continuous wavelet transforms to quantify the quality factor and relaxation frequency of the gas-bearing sediment layer. Knowing or assuming values for the physical parameters of the soil matrix, <span class="hlt">pore</span> water, and free gas, we can invert equations (developed by previous studies) to obtain <span class="hlt">pressure</span> and <span class="hlt">pore</span>-volume fraction values for the free gas. We assess the accuracy of this method by comparing our results to <span class="hlt">pressure</span> data collected from a single piezometer penetrating the gas zone at Finneidfjord, and also by performing the same analysis on Oceanic Drilling Program data from a similar setting. Interpolation of the network of single-channel seismic data from Finneidfjord</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23157939','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23157939"><span>Abdominal compartment syndrome and acute kidney injury due to <span class="hlt">excessive</span> auto-positive end-expiratory <span class="hlt">pressure</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matthew, Dwight; Oxman, David; Djekidel, Karim; Ahmed, Ziauddin; Sherman, Michael</p> <p>2013-02-01</p> <p>Abdominal compartment syndrome is an under-recognized cause of acute kidney injury in critically ill patients. We report a case of a patient with severe obstructive lung disease who, while intubated for respiratory failure, developed abdominal compartment syndrome and oliguric acute kidney injury due to air-trapping and <span class="hlt">excessive</span> auto-positive end-expiratory <span class="hlt">pressure</span> (auto-PEEP; also known as intrinsic PEEP). When chemical paralysis was initiated and the auto-PEEP resolved, the patient's intra-abdominal hypertension rapidly improved and kidney function recovered immediately. Abdominal compartment syndrome secondary to <span class="hlt">excessive</span> auto-PEEP appears to be unreported in the literature; however, any process that significantly increases intrathoracic <span class="hlt">pressure</span> conceivably could cause increased <span class="hlt">pressure</span> to be transmitted to the abdominal compartment, resulting in organ failure. Patients undergoing mechanical ventilation, which puts them at risk of airflow obstruction and the development of intra-abdominal hypertension, should be evaluated for air-trapping and <span class="hlt">excessive</span> auto-PEEP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1057815','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1057815"><span>Evaluation of two-phase relative permeability and capillary <span class="hlt">pressure</span> relations for unstable displacements in a <span class="hlt">pore</span> network</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dehoff, Karl J.; Oostrom, Martinus; Zhang, Changyong; Grate, Jay W.</p> <p>2012-10-29</p> <p>A series of displacement experiments was conducted using five wetting-nonwetting immiscible fluid pairs in a homogenous and uniform <span class="hlt">pore</span> network. The micromodel was initially saturated with either polyethylene glycol 200 (PEG) or water as a wetting fluid, which was subsequently displaced by a nonwetting fluid (dodecane, hexadecane, or mineral oil) at different flow rates. The experiments were designed to allow determinations of nonwetting fluid relative permeabilities ( ), fluid saturations ( ), and capillary <span class="hlt">pressure</span> heads ( ). In the displacements, nonwetting fluid saturations increased with increasing flow rates for all five fluid pairs, and viscous fingering, capillary fingering, and stable displacement were observed. Viscous fingering occurred when PEG was displaced by either dodecane or hexadecane. For the water displacements, capillary fingers were observed at low capillary numbers. Due to unstable fingering phenomena, values for the PEG displacements were smaller than for the water displacements. A fitting exercise using the Brooks-Corey (1964) relationship showed that the fitted entry <span class="hlt">pressure</span> heads are reasonably close to the computed entry <span class="hlt">pressure</span> head. The fitted <span class="hlt">pore</span> geometry factor, S<sub>n</sub> values for the displacements are considerably lower than what is expected for displacements in homogeneous, highly uniform, porous systems, demonstrating the impact of unstable displacement on the apparent value of S<sub>n</sub>. It was shown that a continuum-based multiphase model could be used to predict the average behavior for wetting fluid drainage in a <span class="hlt">pore</span> network as long as independently fitted - and - relations are used. The use of a coupled approach through the Brooks-Corey <span class="hlt">pore</span> geometry factor underpredicts observed values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7380519','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7380519"><span>Control of arterial <span class="hlt">pressure</span> and renal function during glucocorticoid <span class="hlt">excess</span> in dogs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hall, J E; Morse, C L; Smith, M J; Young, D B; Guyton, A C</p> <p>1980-01-01</p> <p>This study was designed to investigate the long-term effects of glucocorticoids on the control of mean arterial <span class="hlt">pressure</span> (MAP) and renal function. Infusion of 10 mg/day of methylprednisolone (MP), a glucocorticoid with minimal mineralocorticoid activity, for 10 days in six intact conscious dogs maintained on a sodium intake of 78 mEq/day resulted in a decrease in MAP from 98 +/- 1 to 89 +/- 2 mm Hg, a decrease in sodium iothalamate space to 89 +/- 2% of control, and a marked increase in glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and urinary sodium excretion. Chronic infusion of MP at doses of 2--800 mg/day in four dogs maintained on low (5 mEq/day) or high sodium intakes (160--223 mEq/day) also caused increases in GFR and ERPF, as well as natriuresis and decreased sodium iothalamate space, while causing either no change or a slight reduction in MAP. To determine whether glucocorticoids potentiate the chronic effects of angiotensin II (AII) on MAP and renal function, MP was infused in dogs undergoing AII infusion (5 ng/kg/min). During AII hypertension, chronic infusion of 5 or 10 mg/day of MP also resulted in a marked renal vasodilation, natriuresis, and reductions in sodium iothalamate space, while causing small reductions in MAP. Thus, we found no evidence that chronic glucocorticoid <span class="hlt">excess</span> causes hypertension in dogs, or that glucocorticoids potentiate the blood <span class="hlt">pressure</span> or renal effects of AII. Instead, glucocorticoids tended to reduce MAP, probably because of chronic renal vasodilation, increased excretion of sodium, and volume depletion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JHyd..544..195Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JHyd..544..195Z"><span>Water content dynamics at plot scale - comparison of time-lapse electrical resistivity tomography monitoring and <span class="hlt">pore</span> <span class="hlt">pressure</span> modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zieher, Thomas; Markart, Gerhard; Ottowitz, David; Römer, Alexander; Rutzinger, Martin; Meißl, Gertraud; Geitner, Clemens</p> <p>2017-01-01</p> <p>Physically-based dynamic modelling of shallow landslide susceptibility rests on several assumptions and simplifications. However, the applicability of physically-based models is only rarely tested in the field at the appropriate scale. This paper presents results of a spray irrigation experiment conducted on a plot of 100 m2 on an Alpine slope susceptible to shallow landsliding. Infiltrating precipitation applied at a constant rate (27.5 mm/h for 5.3 h) was monitored by means of 2D time-lapse electrical resistivity tomography, combined with time-domain reflectometry sensors installed at various depths. In addition, regolith characteristics were assessed by dynamic cone penetration tests using a light-weight cone penetrometer. The spray irrigation experiment resulted in a vertically progressing wetting front to a depth of 80-100 cm. Below that, the unconsolidated material was already saturated by rainfall in the previous days. The observed mean resistivity reduction attributed to infiltrating water during irrigation was scaled to <span class="hlt">pressure</span> head. Mean variations in <span class="hlt">pore</span> <span class="hlt">pressure</span> were reproduced by a linear diffusion model also used in physically-based dynamic landslide susceptibility modelling. Sensitive parameters (hydraulic conductivity and specific storage) were tested over selected value ranges and calibrated. Calibrated parameter values are within published and experimentally derived ranges. The results of the comparison of observations and model results suggest that the model is capable of reproducing mean changes of <span class="hlt">pore</span> <span class="hlt">pressure</span> at a suitable scale for physically-based modelling of shallow landslide susceptibility. However, small-scale variations in <span class="hlt">pore</span> <span class="hlt">pressure</span> that may facilitate the triggering of shallow landslides are not captured by the model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26ES...62a2017H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26ES...62a2017H"><span>Drilling exploration design controlled by <span class="hlt">pore</span> <span class="hlt">pressure</span> prediction from 2D seismic and well data: case study of South Sumatra Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haris, A.; Mulyawan, T.; Riyanto, A.</p> <p>2017-04-01</p> <p>To have safe and economical in drilling design, an information of formation <span class="hlt">pore</span> <span class="hlt">pressure</span> is required. <span class="hlt">Pore</span> <span class="hlt">pressure</span> can be estimated from seismic data using a velocity to <span class="hlt">pore</span> <span class="hlt">pressure</span> transform. The objective of this paper is proposing the drilling exploration design for the case study of South Sumatra field, which is controlled by predicted <span class="hlt">pore</span> <span class="hlt">pressure</span>. The <span class="hlt">pore</span> <span class="hlt">pressure</span> is predicted by using Eaton method that used velocity from 2D seismic and was validated with well log data. The predicted <span class="hlt">pore</span> <span class="hlt">pressure</span> is used to design exploration drilling including casing depth and mud weight. Eaton parameter (N =1.1), shear stress (Ko= 0.6), Gardner (A = 0.198 and B = 0.268), which is used in this works, is gained from existing well data. The velocity model is derived from RMS velocity that should be converted into interval velocity. In addition, this velocity should be validated with the sonic log from existing well. The Normal Compaction Trend (NCT) from interval velocity that was combined with generated previous parameter is used for predicting <span class="hlt">pore</span> <span class="hlt">pressure</span> and fracturing <span class="hlt">pressure</span>. Our experiment shows that based on <span class="hlt">pore</span> <span class="hlt">pressure</span> prediction, the drilling exploration design is divided into three sections. i.e. section 17-1/2”, 12-1/4” and 8-1/2” and four casing sections, i.e. Casing 20‧, K-55, 90 ppf at 160 ft, casing 13-3/8‧, K-55, 54.5 ppf at 1400 ft with mud weight 8.8 - 13.7 ppg, casing 9-5/8 ‧, K-55, 40 ppf at 4000 ft with mud weight 9.5 - 14.0 ppg and casing 7‧, L-80, 26 ppf at 5500 ft with mud weight 10.4 - 14.6 ppg.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T13A2158S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T13A2158S"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> evolution at the plate interface along the Cascadia subduction zone from the trench to the ETS transition zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skarbek, R. M.; Rempel, A. W.; Schmidt, D. A.</p> <p>2010-12-01</p> <p><span class="hlt">Pore</span> fluid <span class="hlt">pressures</span> in subduction zones are a primary control on fault strength and slip dynamics. Numerous studies document elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> in the outer wedge along several margins. Seismic observations and the occurrence of non-volcanic tremor provide additional evidence for the presence of near-lithostatic <span class="hlt">pore</span> <span class="hlt">pressures</span> at the plate interface far down-dip from the trench (~35 km depth). Here we use numerical models in one and two dimensions to evaluate the <span class="hlt">pore</span> <span class="hlt">pressure</span> and compaction state of sediments on the subducting Juan de Fuca plate in Cascadia from the trench to the ETS zone. 2-D models allow <span class="hlt">pressure</span> to diffuse vertically and also laterally normal to strike of the megathrust; 1-D models simulate only vertical diffusion. Model parameters are chosen with reference to two strike-normal profiles: one through central Oregon and one through the Olympic Peninsula of Washington. We examine temporal variations in sediment input to the trench and consider implications for fault strength and permeability as well as the down-dip extent to which compactive dewatering can be considered a significant fluid source. In 1-D, we use a general and fully nonlinear model of sediment compaction derived without making any assumptions regarding stress-strain or porosity-permeability relations and allowing finite strains. In contrast, most previous models of fluid flow in subduction zones have used linear models of diffusion that rely on assumptions of constant sediment permeability and infinitesimal strains for their formulation. Our nonlinear finite-strain model remains valid at greater depths, where stresses and strains are large. Boundary conditions in 1-D are constrained by <span class="hlt">pore</span> <span class="hlt">pressure</span> estimates along the megathrust fault that are based on seismic velocities (e.g. Tobin and Saffer, 2010) and data from consolidation tests conducted on sediments gathered during ODP Leg 204 (Tan, 2001). Initial conditions rely on input sediment thickness; while sediment thickness</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918143S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918143S"><span>Susceptibility of experimental faults to <span class="hlt">pore</span> <span class="hlt">pressure</span> increase: insights from load-controlled experiments on calcite-bearing rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spagnuolo, Elena; Violay, Marie; Nielsen, Stefan; Cornelio, Chiara; Di Toro, Giulio</p> <p>2017-04-01</p> <p>Fluid <span class="hlt">pressure</span> has been indicated as a major factor controlling natural (e.g., L'Aquila, Italy, 2009 Mw 6.3) and induced seismicity (e.g., Wilzetta, Oklahoma, 2011 Mw 5.7). Terzaghi's principle states that the effective normal stress is linearly reduced by a <span class="hlt">pore</span> <span class="hlt">pressure</span> (Pf) increase σeff=σn(1 - αPf), where the effective stress parameter α, may be related to the fraction of the fault area that is flooded. A value of α =1 is often used by default, with Pf shifting the Mohr circle towards lower normal effective stresses and anticipating failure on pre-existing faults. However, within a complex fault core of inhomogeneous permeability, α may vary in a yet poorly understood way. To shed light on this problem, we conducted experiments on calcite-bearing rock samples (Carrara marble) at room humidity conditions and in the presence of <span class="hlt">pore</span> fluids (drained conditions) using a rotary apparatus (SHIVA). A pre-cut fault is loaded by constant shear stress τ under constant normal stress σn=15 MPa until a target value corresponding roughly to the 80 % of the frictional fault strength. The <span class="hlt">pore</span> <span class="hlt">pressure</span> Pf is then raised with regular <span class="hlt">pressure</span> and time steps to induce fault instability. Assuming α=1 and a threshold for instability τp_eff=μp σeff, the experiments reveal that an increase of Pf does not necessarily induce an instability even when the effective strength threshold is largely surpassed (e.g., τp_eff=1.3 μpσeff). This result may indicate that the Pf increase did not instantly diffuse throughout the slip zone, but took a finite time to equilibrate with the external imposed <span class="hlt">pressure</span> increase due to finite permeability. Under our experimental conditions, a significant departure from α=1 is observed provided that the Pf step is shorter than about < 20s. We interpret this delay as indicative of the diffusion time (td), which is related to fluid penetration length l by l = √ κtd-, where κ is the hydraulic diffusivity on the fault plane. We show that a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15551324','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15551324"><span>On the analyses of mixture vapor <span class="hlt">pressure</span> data: the hydrogen peroxide/water system and its <span class="hlt">excess</span> thermodynamic functions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Manatt, Stanley L; Manatt, Margaret R R</p> <p>2004-12-03</p> <p>Reported here are some aspects of the analysis of mixture vapor <span class="hlt">pressure</span> data using the model-free Redlich-Kister approach that have heretofore not been recognized. These are that the pure vapor <span class="hlt">pressure</span> of one or more components and the average temperature of the complex apparatuses used in such studies can be obtained from the mixture vapor <span class="hlt">pressures</span>. The findings reported here raise questions regarding current and past approaches for analyses of mixture vapor <span class="hlt">pressure</span> data. As a test case for this analysis approach the H2O2-H2O mixture vapor <span class="hlt">pressure</span> measurements reported by Scatchard, Kavanagh, and Tickner (G. Scatchard, G. M. Kavanagh, L. B. Ticknor, J. Am. Chem. Soc. 1952, 74, 3715-3720; G. M. Kavanagh, PhD. Thesis, Massachusetts Institute of Technology (USA), 1949) have been used; there is significant recent interest in this system. It was found that the original data is fit far better with a four-parameter Redlich-Kister <span class="hlt">excess</span> energy expansion with inclusion of the pure hydrogen peroxide vapor <span class="hlt">pressure</span> and the temperature as parameters. Comparisons of the present results with the previous analyses of this suite of data exhibit significant deviations. A precedent for consideration of iteration of temperature exists from the little-known work of Uchida, Ogawa, and Yamaguchi (S. Uchida, S. Ogawa, M. Yamaguchi, Japan Sci. Eng. Sci. 1950, 1, 41-49) who observed significant variations of temperature from place to place within a carefully insulated apparatus of the type traditionally used in mixture vapor <span class="hlt">pressure</span> measurements. For hydrogen peroxide, new critical constants and vapor <span class="hlt">pressure</span>-temperature equations needed in the analysis approach described above have been derived. Also temperature functions for the four Redlich-Kister parameters were derived, that allowed calculations of the <span class="hlt">excess</span> Gibbs energy, <span class="hlt">excess</span> entropy, and <span class="hlt">excess</span> enthalpy whose values at various temperatures indicate the complexity of H2O2-H2O mixtures not evident in the original analyses</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T22A..06K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T22A..06K"><span>10+ years of ACORK: Continuous <span class="hlt">pore</span> <span class="hlt">pressure</span> record from the decollement zone at Nankai Trough off Muroto</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinoshita, M.; Davis, E. E.; Becker, K.; Miyazaki, J.; Hulme, S.; Mendrum, R.; Toki, T.; Wheat, C. G.; Kasaya, T.</p> <p>2012-12-01</p> <p><span class="hlt">Pore</span> <span class="hlt">pressure</span> and hydrological properties play key roles in governing coupling and slip behavior along the subducting plate interface. During the KR22-12 cruise, three dives were completed using ROV KAIKO onboard R/V KAIREI during Dec. 20-25, 2011, to retrieve <span class="hlt">pore</span> <span class="hlt">pressure</span> data and interstitial fluid samples from ACORKs at ODP Holes 808I and 1173B situated landward and seaward of the deformation front in the Nankai Trough off Cape Muroto. With 3-year-long and a 4-year-long new data records from Holes 808I and 1173B, respectively, we now have over 10-year-long continuous <span class="hlt">pressure</span> records since June 2001 at both sites. Data from most monitoring depths show systematic variations in average <span class="hlt">pressure</span>, and in formation <span class="hlt">pressure</span> response to seafloor tidal loading. In 2005 and 2009, we observed significant decrease in the amplitudes of <span class="hlt">pressure</span> response to semi-diurnal tidal loading at Hole 808I. Transient changes were observed at the time of several nearby earthquakes, including the 2011 Mar. 11 Tohoku earthquake, followed by long-lasting <span class="hlt">pressure</span> changes in both holes starting on Mar. 23, 2011. Gas-tight fluid sampling operations were successfully carried out from the hydraulic port attached to the swellable packer inserted within the ACORK head at Hole 808I. The swellable packer was set in order to isolate the décollement zone that lies roughly 20 m below the bottom of casing at 922 m below the seafloor. We observed shimmering water venting through the port, and the flow rate was measured using a ball-type flowmeter. Fluid samples looked muddy, probably as a result of staining from the casing steel. We believe that the packer seal at the ACORK head is set properly, although the <span class="hlt">pore</span> <span class="hlt">pressure</span> at 922 m does not seem to have increased up to 2011. Still, the observed fluid seepage suggests a significant amount of fluid evacuated from the décollement zone since ACORK installation, which may have changed its hydrogeological condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20003916','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20003916"><span><span class="hlt">Pressure</span> and temperature dependence of <span class="hlt">excess</span> enthalpies of methanol + tetraethylene glycol dimethyl ether and methanol + polyethylene glycol dimethyl ether 250</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lopez, E.R.; Coxam, J.Y.; Fernandez, J.; Grolier, J.P.E.</p> <p>1999-12-01</p> <p>The <span class="hlt">excess</span> molar enthalpies at 323.15 K, 373.15 K, and 423.15 K, at 8 MPa, are reported for the binary mixtures methanol + tetraethylene glycol dimethyl ether (TEGDME) and methanol + poly(ethylene glycol) dimethyl ether 250 (PEGDME 250). <span class="hlt">Excess</span> molar enthalpies were determined with a Setaram C-80 calorimeter equipped with a flow mixing cell. For both systems, the <span class="hlt">excess</span> enthalpies are positive over the whole composition range, increasing with temperature. The H{sup E}(x) curves are slightly asymmetrical, and their maxima are skewed toward the methanol-rich region. The <span class="hlt">excess</span> enthalpies slightly change with the <span class="hlt">pressure</span>, the sign of this change being composition-dependent. In the case of mixtures with TEGDME, the experimental H{sup E} values have been compared with those predicted with the Gmehling et al. version of UNIFAC (Dortmund) and the Nitta-Chao and DISQUAC group contribution models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRB..117.3215F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRB..117.3215F"><span>Sample dilation and fracture in response to high <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and strain rate in quartz-rich sandstone and siltstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>French, M. E.; Boutt, D. F.; Goodwin, L. B.</p> <p>2012-03-01</p> <p>Natural hydraulic fractures (NHFs) are inferred to form where <span class="hlt">pore</span> <span class="hlt">pressure</span> exceeds the least compressive stress by an amount equal to the tensile strength of the rock. We improved upon an experimental protocol that meets the NHF criterion within cylindrical samples with the most tensile effective stress parallel to the sample axis. The effective tensile stresses achieved during these experiments ranged from 17-47 MPa. The <span class="hlt">pore</span> fluids used had higher viscosities than water and the axial strain rate was rapid (˜10-3s-1) to delay dissipation of fluid <span class="hlt">pressure</span> by flow. Four experiments on St. Peter Sandstone samples and two on an Abo Formation siltstone sample were performed under these conditions and under drained conditions. None of the drained experiments resulted in failure, but all of the sandstone and one of the siltstone samples fractured in response to elevated <span class="hlt">pore</span> <span class="hlt">pressures</span>. Consistent with field and theoretical studies, mechanical heterogeneity was a first order control on fracture location. In the absence of mesoscopic heterogeneity, fracture location coincided with the maximum <span class="hlt">pore</span> <span class="hlt">pressure</span>. Samples responded to elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> and differential stresses by dilating, the magnitude of which was sufficient to achieve atmospheric <span class="hlt">pore</span> <span class="hlt">pressure</span>. Samples failed 2 to 250 s after experiencing the greatest <span class="hlt">pore</span> <span class="hlt">pressures</span>, when the effective stresses were no longer tensile. Thus, the high <span class="hlt">pore</span> <span class="hlt">pressures</span> and effective tensile stresses experienced early in the experiments were sufficient to fracture the rocks, even though they were not sustained until failure. These results provide insight into processes of fluid-driven fracture formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7097553','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7097553"><span>In-situ method for determining <span class="hlt">pore</span> size distribution, capillary <span class="hlt">pressure</span> and permeability</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vinegar, H.J.; Waxman, M.H.</p> <p>1987-02-17</p> <p>A method is described for determining the <span class="hlt">pore</span> sizes entered by the oil phase in an oil-bearing formation, comprising: logging the formation of interest with an induced polarization logging tool having at least one source electrode; computing from the induced polarization measurements obtained by the logging tool a normalized induced polarization response function; obtaining core material from the formation of interest; extracting the water and hydrocarbons from the core material; resaturating the core material with formation brine; measuring the normalized induced polarization response function for the core material; and determining the <span class="hlt">pore</span> sizes containing oil in the formation by comparing the normalized induced polarization response function from the formation with the normalized induced polarization response function of the core.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BVol...77...96C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BVol...77...96C"><span>Influence of slope angle on <span class="hlt">pore</span> <span class="hlt">pressure</span> generation and kinematics of pyroclastic flows: insights from laboratory experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chédeville, Corentin; Roche, Olivier</p> <p>2015-11-01</p> <p>The influence of slope angle on <span class="hlt">pore</span> <span class="hlt">pressure</span> generation and kinematics of fines-rich pyroclastic flows was investigated through laboratory experiments. Granular flows were generated by the release of a column of fine glass beads ( d = 0.08 mm) in an inclined channel (0-30°). The granular column could be fluidized while the channel base was either smooth or made rough by glued beads of 3 mm diameter. <span class="hlt">Pore</span> <span class="hlt">pressure</span> measurements reveal that the degree of autofluidization, caused by air escaping from the substrate interstices into which flow particles settled, was high at all slope angles. Flow runout increase due to autofluidization, however, was reduced at slope angle higher than ˜12° because of the occurrence of a strong deceleration phase that limited the flow duration. This is probably caused by the combination of flow head thinning at increased slope angle and settling of particles into the substrate interstices until the flow ran out of mass. Analysis of high-speed videos suggests that ingestion of ambient air at the flow front did not occur, even on steep slopes of 30°. Experiments at inclinations close to (25°) or slightly higher (30°) than the repose angle of the granular material (28.5°) revealed the formation of a thin basal deposit that was then eroded as the flow thickness and velocity gradually decreased. Our study suggests that air escape from substrate interstices in nature can be a significant external cause of <span class="hlt">pore</span> <span class="hlt">pressure</span> generation that favors low energy dissipation and long runout distances of pyroclastic flows on moderate topographies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T13A2355V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T13A2355V"><span>Slip-weakening zone sizes at nucleation of catastrophic subaerial and submarine landslides by gradually increasing <span class="hlt">pore</span> <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viesca, R. C.; Rice, J. R.</p> <p>2011-12-01</p> <p>We address the nucleation of dynamic landslide rupture in response to gradual <span class="hlt">pore</span> <span class="hlt">pressure</span> increases. Nucleation marks the onset of acceleration of the overlying slope mass due to the suddenly rapid enlargement of a sub-surface zone of shear failure, previously deforming quasi-statically. We model that zone as a planar surface undergoing initially linear slip-weakening frictional failure within a bordering linear-elastic medium. The results are also relevant to earthquake nucleation. The sub-surface rupture zone considered runs parallel to the free surface of a uniform slope, under a 2D plane-strain deformation state. We show results for ruptures with friction coefficients following linear slip weakening (i.e., the residual friction is not yet reached). For spatially broad increases in <span class="hlt">pore</span> <span class="hlt">pressure</span>, the nucleation length depends on a ratio of depth to a cohesive zone length scale. In the very broad-increase limit, a direct numerical solution for nucleation lengths compares well with solutions to a corresponding eigenvalue problem (similar to Uenishi and Rice [JGR '03]), in which spatial variations in normal stress are neglected. We estimate nucleation lengths for subaerial and submarine conditions using data [e.g., Bishop et al., Géotech. '71; Stark et al., JGGE '05] from ring-shear tests on sediments (peak friction fp = 0.5, frictional slip-weakening rate within the range w = -df/d(slip) = 0.1/cm-1/cm). We assume that only pre-stresses, and not material properties, vary with depth. With such fp and w, we find for a range of subsurface depths and shear moduli μ that nucleation lengths are typically several hundred meters long for shallow undersea slopes, and up to an order of magnitude less for steeper slopes on the Earth's surface. In the submarine case, this puts nucleation lengths in a size range comparable to observed <span class="hlt">pore-pressure</span>-generated seafloor disturbances as pockmarks [e.g., Gay et al., MG '06].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19926207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19926207"><span>In situ measurement of soil moisture and <span class="hlt">pore</span>-water <span class="hlt">pressures</span> in an 'incipient' landslide: Lake Tutira, New Zealand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hawke, Richard; McConchie, Jack</p> <p>2011-02-01</p> <p>The immediate cost of shallow regolith landslides in New Zealand has been estimated to exceed US$33M annually. Since the majority of these landslides occur during prolonged wet conditions, or intense rainstorms, moisture conditions are a critical control. The nature, dynamics, and character of soil moisture conditions, and the piezometric response to rainfall, have been recorded within an 'incipient' landslide for more than 5 years. The study site, on pastoral hill country within the Lake Tutira catchment in northern Hawkes Bay, is typical of large areas of New Zealand episodically affected by extensive landsliding. Detailed continuous measurements show that both the soil moisture and piezometric response within the regolith are highly storm- and site-specific. The development of positive <span class="hlt">pore</span> <span class="hlt">pressures</span> is infrequent; they form only during intense rainstorms, and persist for a short time. The hydraulic response of the soil is primarily a function of storm characteristics, but this response can be modified by antecedent moisture conditions, topographic position, and heterogeneity of soil properties. Stability analysis shows that most slopes in the study area are significantly steeper than can be explained by the frictional strength of the regolith. Measured hydraulic conditions also show that positive <span class="hlt">pore</span>-water <span class="hlt">pressures</span> alone do not trigger slope instability. A recent slope failure followed a period of extremely high antecedent moisture conditions, and occurred when maximum soil moisture conditions, though not <span class="hlt">pore</span>-water <span class="hlt">pressures</span>, were recorded. Increased moisture content of the regolith reduces matric tension, and therefore effective cohesion of the soil. This cohesion is critical to maintaining stability of the regolith on these slopes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19892065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19892065"><span>Impact of <span class="hlt">excess</span> body weight on arterial structure, function, and blood <span class="hlt">pressure</span> in firefighters.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fahs, Christopher A; Smith, Denise L; Horn, Gavin P; Agiovlasitis, Stamatis; Rossow, Lindy M; Echols, George; Heffernan, Kevin S; Fernhall, Bo</p> <p>2009-11-15</p> <p>Cardiovascular disease is the leading cause of death among firefighters. The purpose of the present study was to examine the effect of <span class="hlt">excess</span> body weight on arterial structure and function and blood <span class="hlt">pressure</span> (BP) in relatively young, apparently healthy, firefighters. The body mass index, brachial BP, carotid BP, aortic BP, radial augmentation index, central pulse wave velocity, forearm blood flow, forearm vasodilatory capacity, carotid arterial compliance, carotid intima-media thickness, and brachial flow-mediated dilation were assessed in 110 firefighters (aged 29.7 +/- 8.0 years). The group was divided into equal tertiles according to the body mass index (<25.9, 25.9 to 29.4, and >or=29.5 kg/m(2)). Group differences in hemodynamics, anthropometrics, microvascular function, and macrovascular structure and function were tested using multivariate analysis of variance. The obese group was older, heavier, and had a larger waist circumference compared to the lean and overweight groups (p <0.05). The overweight group was also older, heavier, and had a larger waist circumference than the lean group (p <0.05). Compared to the lean group, the overweight and obese groups had a greater systolic BP (p <0.05). The obese group also had a significantly greater mean arterial BP and carotid systolic BP than the lean group (p <0.05). The obese group had greater beta stiffness and elastic modulus compared to the lean and overweight groups (p <0.05), but no group differences were found in endothelial function. In conclusion, in a population of relatively young firefighters, an increased body mass index was associated with elevated peripheral BP and arterial stiffness, with no apparent decrements in endothelial function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21825327','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21825327"><span>Impact of the carbon <span class="hlt">pore</span> size and topology on the equilibrium quantum sieving of hydrogen isotopes at zero coverage and finite <span class="hlt">pressures</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester</p> <p>2009-04-08</p> <p>Carbonaceous slit-shaped and square-shaped <span class="hlt">pores</span> efficiently differentiate adsorbed hydrogen isotopes at 77 and 33 K. Extensive path integral Monte Carlo simulations revealed that the square-shaped carbon <span class="hlt">pores</span> enhanced the selectivity of deuterium over hydrogen in comparison to equivalent slit-shaped carbon <span class="hlt">pores</span> at zero coverage as well as at finite <span class="hlt">pressures</span> (i.e. quantum sieving of hydrogen isotopes is <span class="hlt">pore</span>-topology-dependent). We show that this enhancement of the D(2)/H(2) equilibrium selectivity results from larger localization of hydrogen isotopes in square-shaped <span class="hlt">pores</span>. The operating <span class="hlt">pressures</span> for efficient quantum sieving of hydrogen isotopes are strongly dependent on the topology as well as on the size of the carbon <span class="hlt">pores</span>. However, for both considered carbon <span class="hlt">pore</span> topologies the highest D(2)/H(2) separation factor is observed at zero-coverage limit. Depending on carbon <span class="hlt">pore</span> size and topology we predicted monotonic decreasing and non-monotonic shape of the D(2)/H(2) equilibrium selectivity at finite <span class="hlt">pressures</span>. For both kinds of carbonaceous <span class="hlt">pores</span> of molecular sizes we predict high compression of hydrogen isotopes at 77 and 33 K (for example, the <span class="hlt">pore</span> density of compressed hydrogen isotopes at 77 K and 0.25 MPa in a square-shaped carbon <span class="hlt">pore</span> of size 2.6 Å exceeds 60 mmol cm(-3); for comparison, the liquid density of para-H(2) at 30 K and 30 MPa is 42 mmol cm(-3)). Finally, by direct comparison of simulation results with experimental data it is explained why 'ordinary' carbonaceous materials are not efficient quantum sieves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAG...135...77B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAG...135...77B"><span>Sensitivity analysis of effective fluid and rock bulk modulus due to changes in <span class="hlt">pore</span> <span class="hlt">pressure</span>, temperature and saturation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhakta, Tuhin; Avseth, Per; Landrø, Martin</p> <p>2016-12-01</p> <p>Fluid substitution plays a vital role in time-lapse seismic modeling and interpretation. It is, therefore, very important to quantify as exactly as possible the changes in fluid bulk modulus due to changes in reservoir parameters. In this paper, we analyze the sensitivities in effective fluid bulk modulus due to changes in reservoir parameters like saturation, <span class="hlt">pore-pressure</span> and temperature. The sensitivities are analyzed for two extreme bounds, i.e. the Voigt average and the Reuss average, for various fluid combinations (i.e. oil-water, gas-water and gas-oil). We quantify that the effects of <span class="hlt">pore-pressure</span> and saturation changes are highest in the case of gas-water combination, while the effect of temperature is highest for oil-gas combination. Our results show that sensitivities vary with the bounds, even for same amount of changes in any reservoir parameter. In 4D rock physics studies, we often neglect the effects of <span class="hlt">pore-pressure</span> or temperature changes assuming that those effects are negligible compare to the effect due to saturation change. Our analysis shows that <span class="hlt">pore-pressure</span> and temperature changes can be vital and sometimes higher than the effect of saturation change. We investigate these effects on saturated rock bulk modulus. We first compute frame bulk modulus using the Modified Hashin Shtrikman (MHS) model for carbonate rocks and then perform fluid substitution using the Gassmann equation. We consider upper bound of the MHS as elastic behavior for stiffer rocks and lower bound of the MHS as elastic behavior for softer rocks. We then investigate four various combinations: stiff rock with upper bound (the Voigt bound) as effective fluid modulus, stiff rock with lower bound (Reuss bound) as effective fluid modulus, soft rock with upper bound as effective fluid modulus and soft rock with lower bound as effective fluid modulus. Our results show that the effect of any reservoir parameter change is highest for soft rock and lower bound combination and lowest</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1327095','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1327095"><span>Predicting Stress vs. Strain Behaviors of Thin-Walled High <span class="hlt">Pressure</span> Die Cast Magnesium Alloy with Actual <span class="hlt">Pore</span> Distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Choi, Kyoo Sil; Barker, Erin; Cheng, Guang; Sun, Xin; Forsmark, Joy; Li, Mei</p> <p>2016-01-06</p> <p>In this paper, a three-dimensional (3D) microstructure-based finite element modeling method (i.e., extrinsic modeling method) is developed, which can be used in examining the effects of porosity on the ductility/fracture of Mg castings. For this purpose, AM60 Mg tensile samples were generated under high-<span class="hlt">pressure</span> die-casting in a specially-designed mold. Before the tensile test, the samples were CT-scanned to obtain the <span class="hlt">pore</span> distributions within the samples. 3D microstructure-based finite element models were then developed based on the obtained actual <span class="hlt">pore</span> distributions of the gauge area. The input properties for the matrix material were determined by fitting the simulation result to the experimental result of a selected sample, and then used for all the other samples’ simulation. The results show that the ductility and fracture locations predicted from simulations agree well with the experimental results. This indicates that the developed 3D extrinsic modeling method may be used to examine the influence of various aspects of <span class="hlt">pore</span> sizes/distributions as well as intrinsic properties (i.e., matrix properties) on the ductility/fracture of Mg castings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B11B0013J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B11B0013J"><span>Characterization of Gas-Hydrate Sediment: In Situ Evaluation of Hydrate Saturation in <span class="hlt">Pores</span> of <span class="hlt">Pressured</span> Sedimental Samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, Y.; Konno, Y.; Kida, M.; Nagao, J.</p> <p>2014-12-01</p> <p>Hydrate saturation of gas-hydrate bearing sediment is a key of gas production from natural gas-hydrate reservoir. Developable natural gas-hydrates by conventional gas/oil production apparatus almost exist in unconsolidated sedimental layer. Generally, hydrate saturations of sedimental samples are directly estimated by volume of gas generated from dissociation of gas hydrates in <span class="hlt">pore</span> spaces, porosity data and volume of the sediments. Furthermore, hydrate saturation can be also assessed using velocity of P-wave through sedimental samples. Nevertheless, hydrate saturation would be changed by morphological variations (grain-coating, cementing and <span class="hlt">pore</span>-filling model) of gas hydrates in <span class="hlt">pore</span> spaces. Jin et al.[1,2] recently observed the O-H stretching bands of H2O molecules of methane hydrate in porous media using an attenuated total reflection IR (ATR-IR) spectra. They observed in situ hydrate formation/dissociation process in sandy samples (Tohoku Keisya number 8, grain size of ca. 110 μm). In this presentation, we present IR spectroscopy approach to in situ evaluation of hydrate saturation of <span class="hlt">pressured</span> gas-hydrate sediments. This work was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan. [1] Jin, Y.; Konno, Y.; Nagao, J. Energy Fules, 2012, 26, 2242-2247. [2] Jin, Y.; Oyama, H.; Nagao, J. Jpn. J. Appl. Phys. 2009, 48, No. 108001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T53B1431Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T53B1431Z"><span>Development of a New Analog Test System Capable of Modeling Tectonic Deformation Incorporating the Effects of <span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, M.; Nakajima, H.; Takeda, M.; Aung, T. T.</p> <p>2005-12-01</p> <p>Understanding and predicting the tectonic deformation within geologic strata has been a very important research subject in many fields such as structural geology and petroleum geology. In recent years, such research has also become a fundamental necessity for the assessment of active fault migration, site selection for geological disposal of radioactive nuclear waste and exploration for methane hydrate. Although analog modeling techniques have played an important role in the elucidation of the tectonic deformation mechanisms, traditional approaches have typically used dry materials and ignored the effects of <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>. In order for analog models to properly depict the tectonic deformation of the targeted, large-prototype system within a small laboratory-scale configuration, physical properties of the models, including geometry, force, and time, must be correctly scaled. Model materials representing brittle rock behavior require an internal friction identical to the prototype rock and virtually zero cohesion. Granular materials such as sand, glass beads, or steel beads of dry condition have been preferably used for this reason in addition to their availability and ease of handling. Modeling protocols for dry granular materials have been well established but such model tests cannot account for the <span class="hlt">pore</span> fluid effects. Although the concept of effective stress has long been recognized and the role of <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> in tectonic deformation processes is evident, there have been few analog model studies that consider the effects of <span class="hlt">pore</span> fluid movement. Some new applications require a thorough understanding of the coupled deformation and fluid flow processes within the strata. Taking the field of waste management as an example, deep geological disposal of radioactive waste has been thought to be an appropriate methodology for the safe isolation of the wastes from the human environment until the toxicity of the wastes decays to non-hazardous levels. For the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24324038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24324038"><span>Office blood <span class="hlt">pressure</span>, ambulatory blood <span class="hlt">pressure</span> monitoring, and echocardiographic abnormalities in women with polycystic ovary syndrome: role of obesity and androgen <span class="hlt">excess</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luque-Ramírez, Manuel; Martí, David; Fernández-Durán, Elena; Alpañés, Macarena; Álvarez-Blasco, Francisco; Escobar-Morreale, Héctor F</p> <p>2014-03-01</p> <p>Whether or not blood <span class="hlt">pressure</span> (BP) and heart function of women with polycystic ovary syndrome (PCOS) are altered remains unclear, albeit subtle abnormalities in the regulation of BP observed in these women might suggest a mild masculinization of their cardiovascular system. To study the influence of obesity and androgen <span class="hlt">excess</span> on BP and echocardiographic profiles of women with the syndrome, we conducted a cross-sectional case-control study comparing office and ambulatory BP monitoring, as well as echocardiographic assessments, in 63 premenopausal women with the classic phenotype, 33 nonhyperandrogenic women with regular menses, and 25 young men. Forty-nine subjects were lean and 72 had weight <span class="hlt">excess</span> (body mass index ≥25 kg/m(2)). Participants had no previous history of hypertension and were nonsmokers. Men showed the highest BP readings, and the lowest readings were observed in control women, whereas women with PCOS had intermediate values. Undiagnosed hypertension was more common in subjects with weight <span class="hlt">excess</span> irrespective of sex and hyperandrogenism. Women with PCOS and weight <span class="hlt">excess</span> showed frequencies of previously undiagnosed hypertension that were similar to those of men with weight <span class="hlt">excess</span> and higher than those observed in nonhyperandrogenic women. Lastly, male sex, weight <span class="hlt">excess</span> and hypertension, the latter in men as well as in women with PCOS, increased left ventricular wall thickness. In summary, our results show that patients with classic PCOS and weight <span class="hlt">excess</span> frequently have undiagnosed BP abnormalities, leading to target organ damage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011589','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011589"><span>Rapid intrusion of magma into wet rock: groundwater flow due to <span class="hlt">pore</span> <span class="hlt">pressure</span> increases.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Delaney, P.T.</p> <p>1982-01-01</p> <p>Analytical and numerical solutions are developed to simulate the <span class="hlt">pressurization</span>, expansion, and flow of groundwater contained within saturated, intact host rocks subject to sudden heating from the planar surface of an igneous intrusion. For most rocks, water diffuses more rapidly than heat, assuring that groundwater is not heated along a constant-volume <span class="hlt">pressure</span> path and that thermal expansion and <span class="hlt">pressurization</span> adjacent to the intrusion drives a flow that extends well beyond the heated region. -from Author</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T53B2710H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T53B2710H"><span>In-situ Stresses, <span class="hlt">Pore</span>-fluid <span class="hlt">Pressures</span> and Uplift Erosion in Relation to Active Thrust Faulting in western Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hung, J.; Yen, P.; Wang, L.</p> <p>2012-12-01</p> <p>We have studied the in-situ stresses, <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> and amounts of uplift erosion (UE) from petroleum wells drilled in the Hsinchu-Taichung area of western Taiwan Fold-thrust Belt. The average gradient of regional vertical stress (Sv) calculated from formation density logs is about 23 MPa/km. The magnitude of <span class="hlt">pore</span> <span class="hlt">pressure</span> (Pp) is estimated from mud <span class="hlt">pressure</span>, gas cut and repeat formation test (RFT) in reservoir sandstone, and sonic logs. P-wave travel time in shale (STT) is used to determine the fluid-retention depth (ZFRD) which defines current fully compacted sediments with hydrostatic <span class="hlt">pressures</span> above and undercompacted, overpressured zones below. Regional ZFRD is ~ 3 km except in the Chuhuangkeng anticline, where ZFRD is at shallower depth (~ 2.2 km) and extremely high <span class="hlt">pore</span> <span class="hlt">pressure</span> (λ=0.8) is also observed.. Calculated amounts of UE increase from 0.6 to 4.6 km eastward from outer to inner Foothills belt and correspond to stratigraphy downward and depth upward migration of the ZFRD. Along-strike variation of UE is insignificant. Hydraulic fracturing data including leak-off tests (LOTs) and mini-fracs, as well as qualitative data such as mud loss, are used to constrain the minimum horizontal stress (Shmin). The linear gradient of Shmin is about 17~19 MPa/km, relatively less than that of Sv (~23.60 MPa/km). This implies the in-situ stresses are at strike-slip (SHmax>SV>Shmin) to reverse fault considering focal mechanisms of seismicity are dominant by these two stress regimes in the study area. An upper-bound value of the maximum horizontal stress (SHmax) constrained by frictional limits and the coefficient of friction (μ=0.6) can be estimated from Anderson (1951) faulting criterion. Caliper logs from 8 wells are used to calculate the orientations of the maximum horizontal stresses following the definitions of borehole breakout in World Stress Map. The maximum horizontal stress axis is oriented in NW-SE but local variations occur when passing through</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16..158B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16..158B"><span>Comparison between monitored and modeled <span class="hlt">pore</span> water <span class="hlt">pressure</span> and safety factor in a slope susceptible to shallow landslides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bordoni, Massimiliano; Meisina, Claudia; Zizioli, Davide; Valentino, Roberto; Bittelli, Marco; Chersich, Silvia</p> <p>2014-05-01</p> <p>Shallow landslides can be defined as slope movements affecting superficial deposits of small thicknesses which are usually triggered due to extreme rainfall events, also very concentrated in time. Shallow landslides are hazardous phenomena: in particular, if they happen close to urbanized areas they could cause significant damages to cultivations, structures, infrastructures and, sometimes, human losses. The triggering mechanism of rainfall-induced shallow landslides is strictly linked with the hydrological and mechanical responses of usually unsaturated soils to rainfall events. For this reason, it is fundamental knowing the intrinsic hydro-mechanical properties of the soils in order to assess both susceptibility and hazard of shallow landslide and to develop early-warning systems at large scale. The hydrological data collected by a 20 months monitoring on a slope susceptible to shallow landslides in an area of the North -Eastern Oltrepo Pavese (Northern Apennines, Italy) were used to identify the hydrological behaviors of the investigated soils towards rainfall events. Field conditions under different rainfall trends have also been modeled by using both hydrological and physically-based stability models for the evaluation of the slope safety factor . The main objectives of this research are: (a) to compare the field measured <span class="hlt">pore</span> water <span class="hlt">pressures</span> at different depths with results of hydrological models, in order to evaluate the efficiency of the tested models and to determine how precipitations affect <span class="hlt">pore</span> <span class="hlt">pressure</span> development; (b) to compare the time trends of the safety factor that have been obtained by applying different stability models; (c) to evaluate, through a sensitivity analysis, the effects of soil hydrological properties on modeling <span class="hlt">pore</span> water <span class="hlt">pressure</span> and safety factor. The test site slope where field measurements were acquired is representative of other sites in Northern Apennines affected by shallow landslides and is characterized by medium</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS32A..06A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS32A..06A"><span>Instantaneous Sediment Bed Level Response to Wave-induced <span class="hlt">Pore-pressure</span> Gradients on a Surfzone Sandbar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anderson, D. L.; Cox, D. T.; Mieras, R.; Puleo, J. A.; Hsu, T. J.</p> <p>2016-12-01</p> <p>Proposed physical mechanisms contributing to onshore sediment transport over sandbar crests and subsequent sandbar migration include boundary layer streaming, Stokes drift, and <span class="hlt">pressure</span> gradients. Both horizontal and vertical gradients may be a physical link for predicting sediment transport because they relate to the strong fluid accelerations at the bed induced by steep, near-breaking waves. To understand the fluid forcing and bed response, a barred beach was constructed in a large-scale wave flume with a fixed profile to control the global wave shoaling and breaking. A moveable sediment layer was placed on the crest of the sandbar to quantify instantaneous sediment bed levels co-located with <span class="hlt">pore</span> <span class="hlt">pressure</span> measurements within the upper several centimeters of the bed. A wide range of wave asymmetries were forced over the same profile in individual trials of regular waves to isolate bed response due to wave motions. The total <span class="hlt">pressure</span> gradient vector derived within the bed exhibited temporal rotations during each wave cycle, directed predominantly upwards under the trough and then rapidly rotating onshore and downwards as the wave front passed. Sharp increases in the onshore-directed <span class="hlt">pressure</span> gradient were correlated with rapid decreases in the bed level on the order of centimeters occurring in less than 0.5 seconds. The initiation of the bed level decrease was coincident with large onshore directed <span class="hlt">pressure</span> gradients corresponding to non-dimensional Sleath parameter values between 0.1 and 0.2, and preceded onshore-directed sheet flow sediment transport. Downward-directed vertical <span class="hlt">pressure</span> gradients increased rapidly during bed failure, remained downward during sheet flow, and were minimal under the wave trough. The magnitude of bed level decrease was positively correlated with the degree of wave asymmetry and exhibited additional dependency on the magnitude of bed shear stress, suggesting <span class="hlt">pressure</span> gradients are important for initiation of transport while total</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023892','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023892"><span>A fault constitutive relation accounting for thermal <span class="hlt">pressurization</span> of <span class="hlt">pore</span> fluid</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Andrews, D.J.</p> <p>2002-01-01</p> <p>The heat generated in a slip zone during an earthquake can raise fluid <span class="hlt">pressure</span> and thereby reduce frictional resistance to slip. The amount of fluid <span class="hlt">pressure</span> rise depends on the associated fluid flow. The heat generated at a given time produces fluid <span class="hlt">pressure</span> that decreases inversely with the square root of hydraulic diffusivity times the elapsed time. If the slip velocity function is crack-like, there is a prompt fluid <span class="hlt">pressure</span> rise at the onset of slip, followed by a slower increase. The stress drop associated with the prompt fluid <span class="hlt">pressure</span> rise increases with rupture propagation distance. The threshold propagation distance at which thermally induced stress drop starts to dominate over frictionally induced stress drop is proportional to hydraulic diffusivity. If hydraulic diffusivity is 0.02 m2/s, estimated from borehole samples of fault zone material, the threshold propagation distance is 300 m. The stress wave in an earthquake will induce an unknown amount of dilatancy and will increase hydraulic diffusivity, both of which will lessen the fluid <span class="hlt">pressure</span> effect. Nevertheless, if hydraulic diffusivity is no more than two orders of magnitude larger than the laboratory value, then stress drop is complete in large earthquakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6823144','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6823144"><span>Near-field stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> observations along the Carrizo Plain segment of the San Andreas fault in California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Castillo, D.A. ); Hickman, S.H. )</p> <p>1996-01-01</p> <p>Preliminary observations of wellbore breakouts from 9 wells drilled to depths approaching 5 km and located within 3-10 km of the San Andreas fault in the Carrizo Plain area indicate maximum principal stress orientations (SHmax) 30-40[degrees] from the fault trend, consistent with high shear stress resolved unto the fault. Analysis of stress orientation data from additional wells located >10 km from the fault confirm previous observations that SHmax stresses are at high angles to the fault trend, consistent with low shear stress on the San Andreas. We suggest that the overall variation in shear stresses resolved onto the fault may be depth dependent, with greater shear stress at shallower depths. Alternatively, these stress rotations observed in the vicinity of the San Andreas might also reflect the influence of local secondary faulting and folding, variations in lithology and/or slip heterogeneties associated with the 1857 M8+ Fort Tejon earthquake. Estimates of crustal <span class="hlt">pore</span> <span class="hlt">pressure</span> inferred from drilling mud-weights and drill-stem tests from wells in the vicinity (<10 km) of the San Andreas fault indicate near-hydrostatic conditions to depths of about 5 km. However, 20-30 km from the San Andreas fault and within the central portions of the southern San Joaquin Valley, crustal <span class="hlt">pore</span> <span class="hlt">pressures</span> approach 60% of the lithostatic load starting at about 3.5 km depth. Thus, our data close to the fault suggests that elevated fluid <span class="hlt">pressures</span> within the fault zone, as proposed to explain the long-term low-strength of the San Andreas, either do not penetrate far into the adjacent crust and/or are confined largely to deeper portions of the fault zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/425467','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/425467"><span>Near-field stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> observations along the Carrizo Plain segment of the San Andreas fault in California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Castillo, D.A.; Hickman, S.H.</p> <p>1996-12-31</p> <p>Preliminary observations of wellbore breakouts from 9 wells drilled to depths approaching 5 km and located within 3-10 km of the San Andreas fault in the Carrizo Plain area indicate maximum principal stress orientations (SHmax) 30-40{degrees} from the fault trend, consistent with high shear stress resolved unto the fault. Analysis of stress orientation data from additional wells located >10 km from the fault confirm previous observations that SHmax stresses are at high angles to the fault trend, consistent with low shear stress on the San Andreas. We suggest that the overall variation in shear stresses resolved onto the fault may be depth dependent, with greater shear stress at shallower depths. Alternatively, these stress rotations observed in the vicinity of the San Andreas might also reflect the influence of local secondary faulting and folding, variations in lithology and/or slip heterogeneties associated with the 1857 M8+ Fort Tejon earthquake. Estimates of crustal <span class="hlt">pore</span> <span class="hlt">pressure</span> inferred from drilling mud-weights and drill-stem tests from wells in the vicinity (<10 km) of the San Andreas fault indicate near-hydrostatic conditions to depths of about 5 km. However, 20-30 km from the San Andreas fault and within the central portions of the southern San Joaquin Valley, crustal <span class="hlt">pore</span> <span class="hlt">pressures</span> approach 60% of the lithostatic load starting at about 3.5 km depth. Thus, our data close to the fault suggests that elevated fluid <span class="hlt">pressures</span> within the fault zone, as proposed to explain the long-term low-strength of the San Andreas, either do not penetrate far into the adjacent crust and/or are confined largely to deeper portions of the fault zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AdWR...46...55A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AdWR...46...55A"><span>Linking <span class="hlt">pore</span>-scale interfacial curvature to column-scale capillary <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armstrong, Ryan T.; Porter, Mark L.; Wildenschild, Dorthe</p> <p>2012-09-01</p> <p>Synchrotron-based tomographic datasets of oil-water drainage and imbibition cycles have been analyzed to quantify phase saturations and interfacial curvature as well as connected and disconnected fluid configurations. This allows for close observation of the drainage and imbibition processes, assessment of equilibrium states, and studying the effects of fluid phase disconnection and reconnection on the resulting capillary <span class="hlt">pressures</span> and interfacial curvatures. Based on this analysis estimates of capillary <span class="hlt">pressure</span> calculated from interfacial curvature can be compared to capillary <span class="hlt">pressure</span> measured externally with a transducer. Results show good agreement between curvature-based and transducer-based measurements when connected phase interfaces are considered. Curvature measurements show a strong dependence on whether an interface is formed by connected or disconnected fluid and the time allowed for equilibration. The favorable agreement between curvature-based and transducer-based capillary <span class="hlt">pressure</span> measurements shows promise for the use of image-based estimates of capillary <span class="hlt">pressure</span> for interfaces that cannot be probed with external transducers as well as opportunities for a detailed assessment of interfacial curvature during drainage and imbibition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1047301','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1047301"><span>Linking <span class="hlt">pore</span>-scale interfacial curvature to column-scale capillary <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Armstrong, Ryan T.; Porter, Mark L.; Wildenschild, Dorthe</p> <p>2012-10-24</p> <p>Synchrotron-based tomographic datasets of oil-water drainage and imbibition cycles have been analyzed to quantify phase saturations and interfacial curvature as well as connected and disconnected fluid configurations. This allows for close observation of the drainage and imbibition processes, assessment of equilibrium states, and studying the effects of fluid phase disconnection and reconnection on the resulting capillary <span class="hlt">pressures</span> and interfacial curvatures. Based on this analysis estimates of capillary <span class="hlt">pressure</span> calculated from interfacial curvature can be compared to capillary <span class="hlt">pressure</span> measured externally with a transducer. Results show good agreement between curvature-based and transducer-based measurements when connected phase interfaces are considered. Curvature measurements show a strong dependence on whether an interface is formed by connected or disconnected fluid and the time allowed for equilibration. The favorable agreement between curvature-based and transducer-based capillary <span class="hlt">pressure</span> measurements shows promise for the use of image-based estimates of capillary <span class="hlt">pressure</span> for interfaces that cannot be probed with external transducers as well as opportunities for a detailed assessment of interfacial curvature during drainage and imbibition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1411799V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1411799V"><span><span class="hlt">Pore</span> <span class="hlt">Pressure</span> Diffusion as a possible mechanism for the Ag. Ioanis 2001 earthquake swarm activity (Gulf of Corinth, Central Greece).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vallianatos, F.; Michas, G.; Papadakis, G.; Sammonds, P.</p> <p>2012-04-01</p> <p>The Gulf of Corinth rift (Central Greece) is one of the most seismotectonically active areas in Europe (Ambraseys and Jackson, 1990; 1997), with an important continental N-S extension of about 13 mm/yr and 6 mm/yr at the west and east part respectively (Clarke et al., 1997a). The seismicity of the area includes 5 main earthquakes of magnitude greater than 5.8 since 1960. In the western part of the rift, where the extension reaches its maximum value, earthquake swarms are often being observed (Bourouis and Cornet, 2009). Such an earthquake crisis has been occurred on 2001 at the southern margin of the west part of the rift. The crisis lasted about 100 days with a major event the Ag. Ioanis earthquake (4.3 Mw) on 8th of April 2001 (Pacchiani and Lyon-Caen, 2010). The possible relation between fluids flow and the observed earthquake swarms at the west part of the Gulf of Corinth rift has been discussed in the works of Bourouis and Cornet (2009) and Pacchiani and Lyon-Caen (2010). In the present work we examine the spatiotemporal properties of the Ag. Ioanis 2001 earthquake swarm, using data from the CRL network (http://crlab.eu/). We connect these properties to a mechanism due to <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion (Shapiro et al., 1997) and we estimate the hydraulic diffusivity and the permeability of the surrounding rocks. A back front of the seismicity (Parotidis et al., 2004) is also been observed, related to the migration of seismicity and the development of a quiescence region near the area of the initial <span class="hlt">pore</span> <span class="hlt">pressure</span> perturbation. Moreover, anisotropy of the hydraulic diffusivity has been observed, revealing the heterogeneity of the surrounding rocks and the fracture systems. This anisotropy is consistent in direction with the fault zone responsible for the Ag. Ioanis earthquake (Pacchiani and Lyon-Caen, 2010). Our results indicate that fluids flow and <span class="hlt">pore</span> <span class="hlt">pressure</span> perturbations are possible mechanisms for the initiation and the evolution of the Ag. Ioanis 2001</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1215286L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1215286L"><span>Effects Of Bedrock Shape And Hillslope Gradient On The <span class="hlt">Pore</span>-Water <span class="hlt">Pressure</span> Development: Implication For Slope Stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lanni, Cristiano; McDonnell, Jeff</p> <p>2010-05-01</p> <p>Shallow Landslides are one of the most important causes of loss of human life and socio-economic damage related to the hydro-geological risk issues. The danger of these phenomena is related to their speed of development, the diffculty of foreseeing their location, and the high density of individual phenomena, whose downhill trajectories have a relevant probability of interfering with urbanized areas. Research activity on precipitation-induced landslides has focused mainly on developing predictive understanding of where and when landslides are likely to occur. Nevertheless, some major aspects that may be related to activation of landslides have been poorly investigated. For instance, landslide susceptibility zones are generally predicted assuming constant thickness of soil over an impervious bedrock layer. Nevertheless, recent studies showed subsurface topography could be a first order control for subsurface water-flow dynamics, because of the effects of its own irregular shape. Tromp-van Meerveld and McDonnell (2006) argued that connectivity of patches of transient saturation were a necessary prerequisite for exceeding the rainfall threshold necessary to drive lateral flow. Connectivity - "how the hillslope architecture controls the filling and spilling of isolated patches of saturation" (Hopp and McDonnell, 2009) - appears to be a possible unifying concept and theoretical platform for moving hillslope and watershed hydrology forward. Connectivity could also have important implications on triggering of shallow landslides, because the particular shape of bedrock may limit the water-flow downhill. Here we present a number of virtual numerical experiments performed to investigate the role of bedrock shape and hillslope gradient on <span class="hlt">pore</span>-water <span class="hlt">pressure</span> development. On this purpose, our test is represented by the subsurface topography of the Panola Experiment Hillslope (PEH). That is because scientific literature on PEH provides substantial documentation about the role</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ijege.uniroma1.it/rivista/5th-international-conference-on-debris-flow-hazards-mitigation-mechanics-prediction-and-assessment','USGSPUBS'); return false;" href="http://www.ijege.uniroma1.it/rivista/5th-international-conference-on-debris-flow-hazards-mitigation-mechanics-prediction-and-assessment"><span>A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>George, David L.; Iverson, Richard M.</p> <p>2011-01-01</p> <p><span class="hlt">Pore</span>-fluid <span class="hlt">pressure</span> plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. <span class="hlt">Pore-pressure</span> feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further effects of this feedback by formulating a new, depth-averaged mathematical model that simulates coupled evolution of granular dilatancy, solid and fluid volume fractions, <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span>, and flow depth and velocity during all stages of debris-flow motion. To illustrate implications of the model, we use a finite-volume method to compute one-dimensional motion of a debris flow descending a rigid, uniformly inclined slope, and we compare model predictions with data obtained in large-scale experiments at the USGS debris-flow flume. Predictions for the first 1 s of motion show that increasing <span class="hlt">pore</span> <span class="hlt">pressures</span> (due to debris contraction) cause liquefaction that enhances flow acceleration. As acceleration continues, however, debris dilation causes dissipation of <span class="hlt">pore</span> <span class="hlt">pressures</span>, and this dissipation helps stabilize debris-flow motion. Our numerical predictions of this process match experimental data reasonably well, but predictions might be improved by accounting for the effects of grain-size segregation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815812V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815812V"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> regime leading to shallow failures in a mountain slope: monitoring and interpretation by soil-atmosphere coupled model.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vaunat, Jean; Hürlimann, Marcel; Luna, Boris</p> <p>2016-04-01</p> <p>The study deals with the onset of debris flows in the "El Rebaixader" basin, located in South Central Pyrenees. The initiation area of debris flows is located on a lateral moraine with a thickness of tens of meters, in which torrential processes and other shallow mass movements have generated a large scarp with steep slopes. To follow slope evolution towards shallow failure, different sensors have been installed to monitor meteorological data and hydraulic variables at shallow depths (positive and negative <span class="hlt">pore</span> <span class="hlt">pressure</span>, water content). Measurements are interpreted by means of a thermo-hydro-mechanical coupled Finite Element code provided with a specific boundary condition to model water mass and heat flux exchanged between the ground and the atmosphere, including infiltration, evaporation, sensible heat and solar radiation. Results evidence the different modes of <span class="hlt">pore</span> regime variation imposed, on the one hand, by surface infiltration and evaporation and, on the other hand, by the settlement of a slope parallel flow in a loose layer at some decimetres depth. As a conclusion, the analysis highlights the strong dependency of slope stability to the water regime taking place in slightly more permeable horizons connected to the top of the catchment area rather than to surficial climatic input. On this basis, some keys about debris flow mitigation are finally put forward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/7797','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/7797"><span>Changes in soil moisture and <span class="hlt">pore</span> <span class="hlt">pressure</span> after harvesting a forested hillslope in northern California</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Elizabeth T. Keppeler; Robert R. Ziemer; Peter H. Cafferata</p> <p>1994-01-01</p> <p>Abstract - In 1987, a 0.83-ha zero-order swale was instrumented with 58 pierometers and 25 tensiometers along several hillslope transects. Through 1993, soil moisture conditions were measured by <span class="hlt">pressure</span> transducers connected to a digital data logger recording at 15-minute intervals. In August 1989, the 100-year-old second-growth forest in the swale was felled. Logs...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19228030','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19228030"><span>Bubble snap-off and capillary-back <span class="hlt">pressure</span> during counter-current spontaneous imbibition into model <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Unsal, Evren; Mason, Geoffrey; Morrow, Norman R; Ruth, Douglas W</p> <p>2009-04-09</p> <p>A previous paper (Unsal, E.; Mason, G.; Ruth, D. W.; Morrow, N. R. J. Colloid Interface Sci. 2007, 315, 200-209) reported experiments involving counter-current spontaneous imbibition into a model <span class="hlt">pore</span> system consisting of a rod in an angled slot covered by a glass plate. Such an arrangement gives two tubes with different cross-sections (both size and shape) with an interconnection through the gap between the rod and the plate. In the previous experiments, the wetting phase advanced in the small tube and nonwetting phase retreated in the large tube. No bubbles were formed. In this paper, we study experimentally and theoretically the formation of bubbles at the open end of the large tube and their subsequent snap-off. Such bubbles reduce the capillary back <span class="hlt">pressure</span> produced by the larger tube and can thus have an effect on the local rate of imbibition. In the model <span class="hlt">pore</span> system, the rod was either in contact with the glass, forming two independent tubes, or the rod was spaced from the glass to allow cross-flow between the tubes. For small gaps, there were three distinct menisci. The one with the highest curvature was between the rod and the plate. The next most highly curved was in the smaller tube, and the least highly curved meniscus was in the large tube and this was the tube from which the bubbles developed. The <span class="hlt">pressure</span> in the dead end of the system was recorded during imbibition. Once the bubble starts to form outside of the tube, the <span class="hlt">pressure</span> drops rapidly and then steadies. After the bubble snaps off, the <span class="hlt">pressure</span> rises to almost the initial value and stays essentially constant until the next bubble starts to form. After snap-off, the meniscus in the large tube appears to invade the large tube for some distance. The snap-off is the result of capillary instability; it takes place significantly inside the large tube with flow of wetting phase moving in the angular corners. As imbibition into the small tube progresses, the rate of imbibition decreases and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR51A..07D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR51A..07D"><span><span class="hlt">Pore</span> Characterization of Shale Rock and Shale Interaction with Fluids at Reservoir <span class="hlt">Pressure</span>-Temperature Conditions Using Small-Angle Neutron Scattering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, M.; Hjelm, R.; Watkins, E.; Xu, H.; Pawar, R.</p> <p>2015-12-01</p> <p>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-<span class="hlt">pore</span> confinement is critical for maximizing unconventional oil/gas production. The size and confinement of the nanometer <span class="hlt">pores</span> 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 <span class="hlt">pressure</span>-temperature conditions. We have carried out laboratory investigations exploring quantitative relationship between <span class="hlt">pore</span> 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 <span class="hlt">pressures</span> up to 20000 psi and temperature up to 150 oF. Figure 1 shows our SANS data at different <span class="hlt">pressures</span> with H2O as the <span class="hlt">pressure</span> medium. Our data analysis using IRENA software suggests that the principal changes of <span class="hlt">pore</span> volume in the shale occurred on smaller than 50 nm <span class="hlt">pores</span> and <span class="hlt">pressure</span> at 5000 psi (Figure 2). Our results also suggest that with increasing P, more water flows into <span class="hlt">pores</span>; with decreasing P, water is retained in the <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JSCGE..67..464Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JSCGE..67..464Y"><span>MONITORING OF <span class="hlt">PORE</span> WATER <span class="hlt">PRESSURE</span> AND WATER CONTENT AROUND A HORIZONTAL DRIFT THROUGH EXCAVATION - MEASUREMENT AT THE 140m GALLERY IN THE HORONOBE URL -</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yabuuchi, Satoshi; Kunimaru, Takanori; Kishi, Atsuyasu; Komatsu, Mitsuru</p> <p></p> <p>Japan Atomic Energy Agency has been conducting the Horonobe Underground Research Laboratory (URL) project in Horonobe, Hokkaido, as a part of the research and development program on geological disposal of high-level radioactive waste. <span class="hlt">Pore</span> water <span class="hlt">pressure</span> and water content around a horizontal drift in the URL have been monitored for over 18 months since before the drift excavation was started. During the drift excavation, both <span class="hlt">pore</span> water <span class="hlt">pressure</span> and water content were decreasing. <span class="hlt">Pore</span> water <span class="hlt">pressure</span> has been still positive though it continued to decrease with its gradient gradually smaller after excavation, while water content turned to increase about 6 months after the completion of the excavation. It turned to fall again about 5 months later. An unsaturated zone containing gases which were dissolved in groundwater may have been formed around the horizontal drift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87c6101W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87c6101W"><span>Note: Molecular diffusivity in a small <span class="hlt">pore</span> zeolite measured by a variable <span class="hlt">pressure</span> (piezometric) uptake method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Fei; Kobayashi, Yasukazu; Muhammad, Usman; Wang, Dezheng; Wang, Yao</p> <p>2016-03-01</p> <p>The use of numerical analysis to solve the diffusion equation in the uptake method allowed the measurement of molecular diffusivity in a zeolite with a variable <span class="hlt">pressure</span> around it. The diffusivity was obtained from the data in the measurement of the adsorption isotherm, which means that the diffusivity measurement now needs neither a special instrument nor procedure. The diffusivities of all the gases are readily available from the measurement of their adsorption isotherms and these data include how the diffusivity changes versus adsorbed concentration. The modeling introduced can also be used for a zeolite with a surface barrier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5535415','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5535415"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> diffusion and the hydrologic response of nearly saturated, thin landslide deposits of rainfall</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Haneberg, W.C. )</p> <p>1991-11-01</p> <p>Previous workers have correlated slope failures during rainstorms with rainfall intensity, rainfall duration, and seasonal antecedent rainfall. This note shows how such relationships can be interpreted using a periodic steady-state solution to the well-known linear <span class="hlt">pressure</span> diffusion equation. Normalization of the governing equation yields a characteristic response time that is a function of soil thickness, saturated hydraulic conductivity, and pre-storm effective porosity, and which is analogous to the travel time of a piston wetting front. The effects of storm frequency and magnitude are also successfully quantified using dimensionless attenuation factors and lag times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20568866','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20568866"><span><span class="hlt">Excess</span> of low frequency vibrational modes and glass transition: a molecular dynamics study for soft spheres at constant <span class="hlt">pressure</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flores-Ruiz, Hugo M; Naumis, Gerardo G</p> <p>2009-10-21</p> <p>Using molecular dynamics at constant <span class="hlt">pressure</span>, the relationship between the <span class="hlt">excess</span> of low frequency vibrational modes (known as the boson peak) and the glass transition is investigated for a truncated Lennard-Jones potential. It is observed that the quadratic mean displacement is enhanced by such modes, as predicted using a harmonic Hamiltonian for metastable states. As a result, glasses loose mechanical stability at lower temperatures than the corresponding crystal, since the Lindemann criteria are observed, as is also deduced from density functional theory. Finally, we found that the average force and elastic constant are reduced in the glass due to such <span class="hlt">excess</span> of modes. The ratio between average elastic constants can be approximated using the 2/3 rule between melting and glass transition temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26358196','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26358196"><span>Three-Dimensional Microstructure Reconstruction and Finite Element Simulation of Gas <span class="hlt">Pores</span> in the High-<span class="hlt">Pressure</span> Die-Casting AZ91 Mg Alloy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Wei; Cao, Zhanyi; Sun, Xu; Liu, Haifeng</p> <p>2015-12-01</p> <p>High-<span class="hlt">pressure</span> die-casting (HPDC) AZ91 tensile specimens were used to investigate characteristics of gas <span class="hlt">pores</span> and their effects on mechanical properties of HPDC AZ91 magnesium (Mg) alloy. Combining the stereoscopic morphology of gas <span class="hlt">pores</span> obtained from a three-dimensional (3D) reconstruction technique with the experimental data from uniaxial tensile testing, we worked on finite element simulation to find the relationship between gas <span class="hlt">pores</span> and the mechanical properties of HPDC AZ91 Mg alloy. Results indicate that the 2D metallography images have one-sidedness. Moreover, gas <span class="hlt">pores</span> >100 µm in the center region have a remarkable negative influence on the ultimate tensile strength (UTS) and elongation. With an increase in the size of large gas <span class="hlt">pores</span> in the center region, the UTS and elongation of the material decreases. In addition, the distribution of gas <span class="hlt">pores</span> in the specimens and the areal fraction of gas <span class="hlt">pores</span> >100 µm on cross sections can also affect the UTS and elongation to some extent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28150033','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28150033"><span>Obesity and stress urinary incontinence in women: compromised continence mechanism or <span class="hlt">excess</span> bladder <span class="hlt">pressure</span> during cough?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Swenson, Carolyn W; Kolenic, Giselle E; Trowbridge, Elisa R; Berger, Mitchell B; Lewicky-Gaupp, Christina; Margulies, Rebecca U; Morgan, Daniel M; Fenner, Dee E; DeLancey, John O</p> <p>2017-02-01</p> <p>We compared two hypotheses as to why obesity is associated with stress urinary incontinence (SUI): (1) obesity increases demand on the continence system (e.g. higher cough <span class="hlt">pressure</span>) and (2) obesity compromises urethral function and urethrovaginal support. A secondary analysis was performed using data from a case-control study of SUI in women. Measurements of urethrovaginal support (POP-Q point Aa, urethral axis), urethral function (maximal urethral closure <span class="hlt">pressure</span>, MUCP), and measures of continence system demand (intravesical <span class="hlt">pressures</span> at rest and during maximal cough) were analyzed. Cases and controls were divided into three body mass index (BMI) groups: normal (18.5-24.9 kg/m(2)); overweight (25.0-29.9 kg/m(2)); and obese (≥30 kg/m(2)). Logistic regression models where created to investigate variables related to SUI for each BMI group. Structural equation modeling was used to test the direct and indirect relationships among BMI, SUI, maximal cough <span class="hlt">pressure</span>, MUCP, and POP-Q point Aa. The study included 108 continent controls and 103 women with SUI. MUCP was the factor most strongly associated with SUI in all BMI groups. Maximal cough <span class="hlt">pressure</span> was significantly associated with SUI in obese women (OR 3.191, 95% CI 1.326, 7.683; p < 0.01), but not in normal weight or overweight women. Path model analysis showed a significant relationship between BMI and SUI through maximal cough <span class="hlt">pressure</span> (indirect effect, p = 0.038), but not through MUCP (indirect effect, p = 0.243) or POP-Q point Aa (indirect effect, p = 0.410). Our results support the first hypothesis that obesity is associated with SUI because of increased intravesical <span class="hlt">pressure</span>, which therefore increases demand on the continence mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26420902','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26420902"><span>Face Masks for Noninvasive Ventilation: Fit, <span class="hlt">Excess</span> Skin Hydration, and <span class="hlt">Pressure</span> Ulcers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Visscher, Marty O; White, Cynthia C; Jones, Jennifer M; Cahill, Thomas; Jones, Donna C; Pan, Brian S</p> <p>2015-11-01</p> <p><span class="hlt">Pressure</span> ulcers (stages III and IV) are serious safety events (ie, never events). Healthcare institutions are no longer reimbursed for costs to care for affected patients. Medical devices are the leading cause of pediatric <span class="hlt">pressure</span> ulcers. Face masks for noninvasive ventilation were associated with a high percentage of <span class="hlt">pressure</span> ulcers at our institution. A prospective cohort study investigated factors contributing to <span class="hlt">pressure</span> ulcer development in 50 subjects using face masks for noninvasive ventilation. Color imaging, 3-dimensional surface imaging, and skin hydration measurements were used to identify early skin compromise and evaluate 3 interventions to reduce trauma: (1) a silicone foam dressing, (2) a water/polyethylene oxide hydrogel dressing, and (3) a flexible cloth mask. A novel mask fit technique was used to examine the impact of fit on the potential for skin compromise. Fifty subjects age 10.4 ± 9.1 y participated with color images for 22, hydration for 34, and mask fit analysis for 16. Of these, 69% had diagnoses associated with craniofacial anomalies. Stage I <span class="hlt">pressure</span> ulcers were the most common injury. Skin hydration difference was 317 ± 29 for sites with erythema versus 75 ± 28 for sites without erythema (P < .05) and smallest for the cloth mask (P < .05). Fit distance metrics differed for the nasal, oronasal, and face shield interfaces, with threshold distances being higher for the oronasal mask than the others (P < .05). Areas of high contact were associated with skin erythema and <span class="hlt">pressure</span> ulcers. This fit method is currently being utilized to select best-fit masks from available options, to identify the potential areas of increased tissue <span class="hlt">pressure</span>, and to prevent skin injuries and their complications. Improvement of mask fit is an important priority for improving respiratory outcomes. Strategies to maintain normal skin hydration are important for protecting tissue integrity. Copyright © 2015 by Daedalus Enterprises.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T43C2677K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T43C2677K"><span>Revisit of basal effective friction and <span class="hlt">pore</span> <span class="hlt">pressure</span> for Japan trench from topographic point of view</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koge, H.; Fujiwara, T.; Kodaira, S.; Sasaki, T.; Kameda, J.; Hamahashi, M.; Hamada, Y.; Kimura, G.</p> <p>2013-12-01</p> <p>2011 Tohoku-oki earthquake (Mw9.0) produced a fault rupture, extending to the shallow part of the Japan Trench. Based on the bathymetry difference before and after the earthquake, it is demonstrated that the seafloor on outermost landward slope moved ~50 m east-southeastward towards the trench and uplifted ~7 to 10 m. Although the mechanism of the fault rupture is not clear, deformation and frictional properties beneath the forearc are the key to elucidate this important issue. Kimura et al (2012) focused on seismic reflection data along one seismic transect at the Japan Trench (name the transect), and calculated the basal effective friction of the plate boundary by using the critical taper theory. Limited profiles from narrow area, however, never represent general friction property of the plate boundary in the Japan trench. Therefore, several profiles are examined to investigate for the better understanding along-trench variation of the basal frictional properties. Bathymetric and seismic reflection data were taken before and after the Tohoku-oki earthquake to obtain the following angles; slope angle of upper surface, basal dip of the outer wedge. Acuired angles are limited to only the lowest trench slope of the Japan Trench. The limitation enables us to treat the wedge as a more uniform body than would have been achieved with the whole range of seismic cross sections. Applying the critical taper theory to the individual seismic cross sections, force balance among the interior and base of the wedge, fluid <span class="hlt">pressure</span> ratio, and the basal effective friction of the plate boundary are calculated. Additionally, by using "earth <span class="hlt">pressure</span> theory", we estimated basal effective friction of ~0.15 under the assumption that branching faults act as back-stops in lower slope areas. References Cubas et al., Geophysical Research Letters: DOI:10.1002/grl.50682 Fujiwara et al., Science 2 December 2011: Vol. 334 no. 6060 p. 1240 Wang and Hu, Journal of Geophysical Research, v.111, p1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoJI.203.1072B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoJI.203.1072B"><span>The electrical conductivity of CO2-bearing <span class="hlt">pore</span> waters at elevated <span class="hlt">pressure</span> and temperature: a laboratory study and its implications in CO2 storage monitoring and leakage detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Börner, Jana H.; Herdegen, Volker; Repke, Jens-Uwe; Spitzer, Klaus</p> <p>2015-11-01</p> <p>The electrical rock conductivity is a sensitive indicator for carbon dioxide (CO2) injection and migration processes. For a reliable balancing of the free CO2 in <span class="hlt">pore</span> space with petrophysical models such as Archie's law or for the detection of migrating CO2, detailed knowledge of the <span class="hlt">pore</span> water conductivity during interaction with CO2 is essential but not available yet. Contrary to common assumptions, <span class="hlt">pore</span> water conductivity cannot be assumed constant since CO2 is a reactive gas that dissolves into the <span class="hlt">pore</span> water in large amounts and provides additional charge carriers due to the dissociation of carbonic acid. We consequently carried out systematic laboratory experiments to quantify and analyse the changes in saline <span class="hlt">pore</span> water conductivity caused by CO2 at thermodynamic equilibrium. Electrical conductivity is measured on <span class="hlt">pore</span> water samples for <span class="hlt">pressures</span> up to 30 MPa and temperatures up to 80 °C. The parameter range covers the gaseous, liquid and supercritical state of the CO2 involved. <span class="hlt">Pore</span> water salinities from 0.006 up to 57.27 g L-1 sodium chloride were investigated as well as selective other ion species. At the same time, the CO2 concentration in the salt solution was determined by a wet-chemical procedure. A two-regime behaviour appears: for small salinities, we observe an increase of up to more than factor 3 in the electrical <span class="hlt">pore</span> water conductivity, which strongly depends on the solution salinity (low-salinity regime). This is an expected behaviour, since the additional ions originating from the dissociation of carbonic acid positively contribute to the solution conductivity. However, when increasing salinities are considered this effect is completely diminished. For highly saline solutions, the increased mutual impeding causes the mobility of all ions to decrease, which may result in a significant reduction of conductivity by up to 15 per cent despite the added CO2 (high-salinity regime). We present the data set covering the <span class="hlt">pressure</span>, temperature, salinity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21294305','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21294305"><span>Orbital-free molecular dynamics simulations of a warm dense mixture: Examination of the <span class="hlt">excess-pressure</span> matching rule</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Danel, J-F.; Kazandjian, L.; Zerah, G.</p> <p>2009-06-15</p> <p>A form of the linear mixing rule involving the equality of <span class="hlt">excess</span> <span class="hlt">pressures</span> is tested with various mole fractions and various types of orbital-free molecular dynamics simulations. For all the cases considered, this mixing rule yields, within statistical error, the <span class="hlt">pressure</span> of a mixture of helium and iron obtained by a direct simulation. In an attempt to interpret the robustness of the mixing rule, we show that it can be derived from thermodynamic stability if the system is regarded as a mixture of independent effective average atoms. The success of the mixing rule applied with equations of state including various degrees of approximation leads us to suggest its use in the thermodynamic domain where quantum molecular dynamics can be implemented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AdWR...33..846F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AdWR...33..846F"><span>A semi-analytical model for computation of capillary entry <span class="hlt">pressures</span> and fluid configurations in uniformly-wet <span class="hlt">pore</span> spaces from 2D rock images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frette, O. I.; Helland, J. O.</p> <p>2010-08-01</p> <p>A novel semi-analytical model for computation of capillary entry <span class="hlt">pressures</span> and associated fluid configurations in arbitrary, potentially non-convex, 2D <span class="hlt">pore</span> space geometries at uniform wettability is developed. The model computes all possible centre positions of circular arcs, and physically sound criteria are implemented to determine the set of these arcs that correspond to geometrically allowed interfaces. Interfaces and <span class="hlt">pore</span> boundary segments are connected to form closed boundaries of identified geometrical regions. These regions are classified as either oil regions, located in the wider parts of the <span class="hlt">pore</span> space, or as water regions located in <span class="hlt">pore</span> space constrictions. All possible region combinations are identified and evaluated for each radius value in an iterative procedure to determine the favourable entry radius and corresponding configuration based on minimisation of free energy. The model has been validated by comparison with known analytical solutions in idealised <span class="hlt">pore</span> geometries. In cases where different analytical solutions are geometrically possible, the model generates several oil and water regions, and the valid solution is determined by the region combination that corresponds to the most favourable entry <span class="hlt">pressure</span>, consistent with the analytical solution. Entry <span class="hlt">pressure</span> radii and configurations are computed in strongly non-convex <span class="hlt">pore</span> spaces extracted from an image of Bentheimer sandstone, which demonstrates that the model captures successfully well-known characteristics of capillary behaviour at different wetting conditions. The computations also demonstrate the importance of selecting the fluid configuration of minimum change in free energy. In some cases, a merged region formed by a combination of oil and water regions corresponds to the favourable entry configuration of oil, whereas in other cases, an individual oil region may correspond to the favourable oil entry configuration. It is also demonstrated that oil entry configurations may</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JGRB..111.3410K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JGRB..111.3410K"><span>Broadband hydroseismograms observed by closed borehole wells in the Kamioka mine, central Japan: Response of <span class="hlt">pore</span> <span class="hlt">pressure</span> to seismic waves from 0.05 to 2 Hz</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kano, Yasuyuki; Yanagidani, Takashi</p> <p>2006-03-01</p> <p>We obtained broadband hydroseismograms by monitoring the <span class="hlt">pore</span> <span class="hlt">pressure</span> changes of a rock mass in the Kamioka mine, using borehole wells. The wellhead was sealed to maintain an undrained condition, under which there is no flow of water through the interface between the well and the rock mass. This reduces the wellbore storage effect, which can cause a high-frequency cutoff response for systems of conventional open wells and rock mass. Using these closed borehole wells, 16 hydroseismograms were recorded for earthquakes in a range of magnitudes of 4.5-7.9 and epicentral distances of 1.0°-71.6°. Direct P waves, SV waves converted to P, and Rayleigh phases are clearly observed on the hydroseismograms. The similarity between hydroseismograms and seismograms reveals a clear relationship between radial ground velocity and <span class="hlt">pore</span> <span class="hlt">pressure</span>. The relationship is expressed as a zero-order system, which is characterized by no distortion or time lag between the input and output, and the <span class="hlt">pore</span> <span class="hlt">pressure</span> has no coupling with shear deformation. These results are consistent with an undrained constitutive relation of linear poroelastic theory and confirm that the relation is valid for the seismic frequency range. We determined in situ values of <span class="hlt">pore</span> <span class="hlt">pressure</span> sensitivity to volumetric change of the rock mass, which were then used to estimate in situ Skempton coefficients with values of 0.70-0.85.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AdWR...69...49Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AdWR...69...49Z"><span>Computation of three-phase capillary entry <span class="hlt">pressures</span> and arc menisci configurations in <span class="hlt">pore</span> geometries from 2D rock images: A combinatorial approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Yingfang; Helland, Johan Olav; Hatzignatiou, Dimitrios G.</p> <p>2014-07-01</p> <p>We present a semi-analytical, combinatorial approach to compute three-phase capillary entry <span class="hlt">pressures</span> for gas invasion into <span class="hlt">pore</span> throats with constant cross-sections of arbitrary shapes that are occupied by oil and/or water. For a specific set of three-phase capillary <span class="hlt">pressures</span>, geometrically allowed gas/oil, oil/water and gas/water arc menisci are determined by moving two circles in opposite directions along the <span class="hlt">pore</span>/solid boundary for each fluid pair such that the contact angle is defined at the front circular arcs. Intersections of the two circles determine the geometrically allowed arc menisci for each fluid pair. The resulting interfaces are combined systematically to allow for all geometrically possible three-phase configuration changes. The three-phase extension of the Mayer and Stowe - Princen method is adopted to calculate capillary entry <span class="hlt">pressures</span> for all determined configuration candidates, from which the most favorable gas invasion configuration is determined. The model is validated by comparing computed three-phase capillary entry <span class="hlt">pressures</span> and corresponding fluid configurations with analytical solutions in idealized triangular star-shaped <span class="hlt">pores</span>. It is demonstrated that the model accounts for all scenarios that have been analyzed previously in these shapes. Finally, three-phase capillary entry <span class="hlt">pressures</span> and associated fluid configurations are computed in throat cross-sections extracted from segmented SEM images of Bentheim sandstone. The computed gas/oil capillary entry <span class="hlt">pressures</span> account for the expected dependence of oil/water capillary <span class="hlt">pressure</span> in spreading and non-spreading fluid systems at the considered wetting conditions. Because these geometries are irregular and include constrictions, we introduce three-phase displacements that have not been identified previously in <span class="hlt">pore</span>-network models that are based on idealized <span class="hlt">pore</span> shapes. However, in the limited number of <span class="hlt">pore</span> geometries considered in this work, we find that the favorable displacements are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26ES...39a2031Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26ES...39a2031Z"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> propagation in a permeable thin-layer coal seam based on a dual porosity model: A case of risk prediction of water inrush in coalmines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, B.; Gao, F.; Yang, J. W.; Zhou, G. Q.</p> <p>2016-08-01</p> <p>Thin-layer coal seams, a type of filling coal rock body, are considered aquifer systems made up of dual porosity medium with immediate floor. A numerical simulation for the <span class="hlt">pore</span> <span class="hlt">pressure</span> propagation along a thin-layer coal seam was carried out for the case of the Zhaogezhuang coalmine in China. By valuing the permeability (Kf ) of the thin-layer coal seam, <span class="hlt">pore</span> <span class="hlt">pressure</span> variation with time was simulated and compared to the analytical solutions of a dual porosity model (DPM). The main conclusions were drawn as follow: (1) Seepage in the thin-layer coal seam was predominant in the whole process, and the distance of seepage was lengthened and the <span class="hlt">pore</span> <span class="hlt">pressure</span> decreased with increased Kf , (2) A series of simulated hydraulic graphs demonstrated that the <span class="hlt">pore</span> <span class="hlt">pressure</span> characteristics of peak-occurring and time-lag effects agreed with the analytical solutions of DPM; (3) By adjusting the parameters of DPM, two results of analytical solutions and numerical solutions fit well, particularly in the thin-layer coal seam, (4) The power law relationship between the peak-values and lag time of <span class="hlt">pore</span> <span class="hlt">pressure</span> were derived statistically under consideration of the Kf parameter in the range of 10-8 to 10-10 m2/pa-s orders, and it was reasonable that the Kf of the thin-layer coal seam was in the range of 10-8 m2/pa-s orders. The results were significantly helpful in decision-making for mining water prevention and prediction in practice.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.S31B..02F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.S31B..02F"><span>Size of seismic events during borehole injections: the effects of source mechanisms, stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fischer, T.; Ondovcin, T.; Zhao, P.</p> <p>2012-12-01</p> <p> and space-time distributions, source mechanisms and stress analyses on the available data to shed light on these questions. Our inversion for moment tensors of the Basel injection-induced seismicity shows that the microearthquakes had higher non-DC components during injection than after shut-in. This could be related to the higher stress drops found during injection. We model the <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution and out-flow from the well the numerically solving the diffusion equation for the shut-in and open-well conditions. We compare the results of seismicity analysis with the models of <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution during and after the injection to test the relevancy of several hypotheses of the occurrence of large events. We find that their anomalous occurrence during the shut-in phase is most-likely caused by the transient effects during the stop of injection. The anomalous space occurrence of large events is probably also related to the unequal distribution of faults in the vicinity of the injection well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4454139','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4454139"><span>Extraction of <span class="hlt">pore</span>-morphology and capillary <span class="hlt">pressure</span> curves of porous media from synchrotron-based tomography data</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Feifei; Hingerl, Ferdinand F.; Xiao, Xianghui; Liu, Yijin; Wu, Ziyu; Benson, Sally M.; Toney, Michael F.</p> <p>2015-01-01</p> <p>The elevated level of atmospheric carbon dioxide (CO2) has caused serious concern of the progression of global warming. Geological sequestration is considered as one of the most promising techniques for mitigating the damaging effect of global climate change. Investigations over wide range of length-scales are important for systematic evaluation of the underground formations from prospective CO2 reservoir. Understanding the relationship between the micro morphology and the observed macro phenomena is even more crucial. Here we show Synchrotron based X-ray micro tomographic study of the morphological buildup of Sandstones. We present a numerical method to extract the <span class="hlt">pore</span> sizes distribution of the porous structure directly, without approximation or complex calculation. We have also demonstrated its capability in predicting the capillary <span class="hlt">pressure</span> curve in a mercury intrusion porosimetry (MIP) measurement. The method presented in this work can be directly applied to the morphological studies of heterogeneous systems in various research fields, ranging from Carbon Capture and Storage, and Enhanced Oil Recovery to environmental remediation in the vadose zone. PMID:26039795</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1208861-extraction-pore-morphology-capillary-pressure-curves-porous-media-from-synchrotron-based-tomography-data','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1208861-extraction-pore-morphology-capillary-pressure-curves-porous-media-from-synchrotron-based-tomography-data"><span>Extraction of <span class="hlt">pore</span>-morphology and capillary <span class="hlt">pressure</span> curves of porous media from synchrotron-based tomography data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yang, Feifei; Hingerl, Ferdinand F.; Xiao, Xianghui; ...</p> <p>2015-06-03</p> <p>The elevated level of atmospheric carbon dioxide (CO2) has caused serious concern of the progression of global warming. Geological sequestration is considered as one of the most promising techniques for mitigating the damaging effect of global climate change. Investigations over wide range of length-scales are important for systematic evaluation of the underground formations from prospective CO2 reservoir. Understanding the relationship between the micro morphology and the observed macro phenomena is even more crucial. Here we show Synchrotron based X-ray micro tomographic study of the morphological buildup of Sandstones. We present a numerical method to extract the <span class="hlt">pore</span> sizes distribution ofmore » the porous structure directly, without approximation or complex calculation. We have also demonstrated its capability in predicting the capillary <span class="hlt">pressure</span> curve in a mercury intrusion porosimetry (MIP) measurement. The method presented in this work can be directly applied to the morphological studies of heterogeneous systems in various research fields, ranging from Carbon Capture and Storage, and Enhanced Oil Recovery to environmental remediation in the vadose zone.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26ES...26a2052A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26ES...26a2052A"><span>A deep seated movement in a marly-arenaceous formation: analysis of slope deformation and <span class="hlt">pore</span> <span class="hlt">pressure</span> influence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Assefa, S.; Graziani, A.; Lembo-Fazio, A.</p> <p>2015-09-01</p> <p>The case history of a deep-seated slope movement in a complex rock formation (Marly-Arenaceous Formation) is analyzed. The movement, monitored for more than 20 years, was recognized after the discovery of intense cracking in the concrete lining of a hydraulic tunnel running across the slope. The time history of displacements shows that the ongoing deformation process is essentially a stationary creep phenomenon, also influenced by transient variations in <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution. The slip surface is formed by a tectonized clay gouge layer and the mobilized shear strength is close to residual. The slope has been modelled (UDEC code) as a complex blocky structure defined by several joint sets: bedding joints, inclined and sub-vertical discontinuities. Different geometries of the slip surface, reasonably varied within the range of hypotheses compatible with field evidences, have limited influence on the limit friction angle of the slip surface. Joint patterns have influence on the deformation mode and minor impact on the mobilized friction angle. The model response is less sensitive to the water level at the slope toe as compared to the rise of groundwater table.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1208861','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1208861"><span>Extraction of <span class="hlt">pore</span>-morphology and capillary <span class="hlt">pressure</span> curves of porous media from synchrotron-based tomography data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yang, Feifei; Hingerl, Ferdinand F.; Xiao, Xianghui; Liu, Yijin; Wu, Ziyu; Benson, Sally M.; Toney, Michael F.</p> <p>2015-06-03</p> <p>The elevated level of atmospheric carbon dioxide (CO<sub>2</sub>) has caused serious concern of the progression of global warming. Geological sequestration is considered as one of the most promising techniques for mitigating the damaging effect of global climate change. Investigations over wide range of length-scales are important for systematic evaluation of the underground formations from prospective CO<sub>2</sub> reservoir. Understanding the relationship between the micro morphology and the observed macro phenomena is even more crucial. Here we show Synchrotron based X-ray micro tomographic study of the morphological buildup of Sandstones. We present a numerical method to extract the <span class="hlt">pore</span> sizes distribution of the porous structure directly, without approximation or complex calculation. We have also demonstrated its capability in predicting the capillary <span class="hlt">pressure</span> curve in a mercury intrusion porosimetry (MIP) measurement. The method presented in this work can be directly applied to the morphological studies of heterogeneous systems in various research fields, ranging from Carbon Capture and Storage, and Enhanced Oil Recovery to environmental remediation in the vadose zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26039795','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26039795"><span>Extraction of <span class="hlt">pore</span>-morphology and capillary <span class="hlt">pressure</span> curves of porous media from synchrotron-based tomography data.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Feifei; Hingerl, Ferdinand F; Xiao, Xianghui; Liu, Yijin; Wu, Ziyu; Benson, Sally M; Toney, Michael F</p> <p>2015-06-03</p> <p>The elevated level of atmospheric carbon dioxide (CO2) has caused serious concern of the progression of global warming. Geological sequestration is considered as one of the most promising techniques for mitigating the damaging effect of global climate change. Investigations over wide range of length-scales are important for systematic evaluation of the underground formations from prospective CO2 reservoir. Understanding the relationship between the micro morphology and the observed macro phenomena is even more crucial. Here we show Synchrotron based X-ray micro tomographic study of the morphological buildup of Sandstones. We present a numerical method to extract the <span class="hlt">pore</span> sizes distribution of the porous structure directly, without approximation or complex calculation. We have also demonstrated its capability in predicting the capillary <span class="hlt">pressure</span> curve in a mercury intrusion porosimetry (MIP) measurement. The method presented in this work can be directly applied to the morphological studies of heterogeneous systems in various research fields, ranging from Carbon Capture and Storage, and Enhanced Oil Recovery to environmental remediation in the vadose zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013WRR....49..732S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013WRR....49..732S"><span>A new technique for obtaining high-resolution <span class="hlt">pore</span> <span class="hlt">pressure</span> records in thick claystone aquitards and its use to determine in situ compressibility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Laura A.; van der Kamp, Garth; Jim Hendry, M.</p> <p>2013-02-01</p> <p>Laboratory tests are commonly used to determine properties (vertical compressibility, α; specific storage, SS; and vertical hydraulic conductivity, Kv) of claystone aquitards; however, whether data representative of in situ conditions can be obtained from disturbed samples is questionable. Here, we present a method to determine the in situ α and SS of a thick sequence of Cretaceous aged claystone by estimating the loading efficiency (γ) of a formation from <span class="hlt">pore</span> <span class="hlt">pressure</span> responses to barometric <span class="hlt">pressure</span> fluctuations. We installed 10 vibrating wire <span class="hlt">pressure</span> transducers at different depths (25-325 m below ground) in a thick claystone aquitard by placing them directly within the cement-bentonite grout. Two years of continuous transducer records using this method appeared to provide <span class="hlt">pore</span> <span class="hlt">pressure</span> data with a resolution of better than one part in 105, equivalent to millimeter of hydraulic head change. <span class="hlt">Pore</span> <span class="hlt">pressure</span> responses to barometric <span class="hlt">pressure</span> changes, earth tides, and precipitation events can be clearly identified, and the barometric responses can be easily analyzed. The resulting values of γ (0.6-0.93), α (2.5 × 10-7 to 2.2 × 10-6 kPa-1), and SS (2.6 × 10-5 to 4.5 × 10-6 m-1) all decrease with depth. The results are comparable with the limited existing data for in situ estimates of SS and are as much as an order of magnitude smaller than laboratory estimates of SS for similar aquitard deposits. Our findings suggest that the fully grouted transducer method can provide an accurate and reliable means to monitor <span class="hlt">pore</span> <span class="hlt">pressure</span> changes and to determine in situ parameters for bedrock aquitard systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26032296','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26032296"><span><span class="hlt">Excessive</span> pediatric fasciitis necrotisans due to Pseudomonas aeruginosa infection successfully treated with negative <span class="hlt">pressure</span> wound therapy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Szabó, Levente; Szegedi, István; Kiss, Csongor; Szikszay, Edit; Remenyik, Éva; Csízy, István; Juhász, István</p> <p>2015-01-01</p> <p>The case of a 10-year old female child is described with a history of myeloproliferative disorder having skin, bone and visceral involvement. Bone marrow biopsy revealed histiocytosis X. During chemotherapy necrotizing fasciitis of the lower abdominal wall was diagnosed. Multiple microbiological cultures taken from the wound base revealed Pseudomonas aeruginosa infection. Surgical necrectomy and application of negative <span class="hlt">pressure</span> wound therapy (NPWT) was started together with intensive care treatment for sepsis. As both wound and general condition of the patient improved, autologous split thickness skin grafting was carried out in two sitting under continuing NPWT application. The applied skin grafts showed excellent take, the perilesional subcutaneous recesses resolved and complete healing was achieved after 28 days of NPWT treatment. Proper dermatological diagnosis and immediate escharectomy complemented with application of NPWT can be life-saving in the treatment of necrotizing fasciitis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24629401','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24629401"><span><span class="hlt">Excessive</span> pulse <span class="hlt">pressure</span> response to standing in community population with orthostatic systolic hypertension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Jingsong; Zhou, Yueying; Cao, Kaiwu; Li, Juxiang; Tao, Xuehua; Zhang, Zhihong; Liu, Xin; Liu, Jiaqi; Su, Hai</p> <p>2014-03-01</p> <p>The postural change of pulse <span class="hlt">pressure</span> (PP) in the persons with orthostatic hypertension (OHT) is unclear. This study included 2849 (65.0 ± 9.3 years) community participants. Blood <span class="hlt">pressures</span> (BPs) in supine and standing positions were measured. The differences between upright and supine BP and PP were recorded as ΔBP and ΔPP. The criteria for OHT was ΔBP ≥10 mm Hg, for orthostatic hypotension (OH) was ≤-10 mm Hg and for orthostatic normotension (ONT) was -9 to 9 mm Hg. Fasting blood lipids and glucose were measured. The supine SBP of the sOHT group were similar to that of sONT group (140.9 ± 20.2 mm Hg vs 138.2 ± 19.7 mm Hg), but significantly lower than that of sOH group (151.9 ± 19.2 mm Hg; P < .05). Their PPs were 65.3 ± 15.9, 62.8 ± 14.7, and 71.1 ± 15.1 mm Hg, respectively, and with the similar group difference like SBP. When the position changed from supine to standing, the sOHT group showed PP rise, while sOH and sONT groups showed PP reduction (3.8 ± 7.1 mm Hg vs -17.0 ± 8.5 mm Hg and -5.8 ± 6.6 mm Hg; both P < .05). Thus, the standing PP in the sOHT group was significantly higher than in the sONT (69.1 ± 18.0 mm Hg vs 57.0 ± 15.8 mm Hg; P < .05) and in the sOH (54.2 ± 15.2 mm Hg; P < .05) groups. The postural PP profile varies with the postural responses of SBP. The sOHT group has obviously increased PP and significantly higher standing PP compared with the sONT group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.H21J..05T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.H21J..05T"><span>Studies on deformation/<span class="hlt">pore</span> <span class="hlt">pressure</span> coupling processes at Japanese URLs and the development of ultra-high resolution FBG strain sensors for rock mechanics (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tokunaga, T.; Matsui, H.; Zuyuan, H.; Kashiwai, Y.</p> <p>2009-12-01</p> <p>Generic, purpose-build underground research laboratories have been under construction in Japan. The objective for the construction is to conduct integrated studies on geology, geophysics, hydrogeology, rock mechanics, hydro-geochemistry, etc., to better understand the behavior and long-term stability of subsurface environments and subsurface openings. The Japan Atomic Energy Agency is responsible for the construction and selected two sites, i.e., Mizunami in central Japan and Horonobe in northern tip of Hokkaido, each representing granitic/crystalline rock environment and sedimentary formations, respectively. The construction of the Mizunami URL site began in July 2003, and the shafts reached to 400 m below ground level as of August 2009. The URL is situated in granitic rock masses including highly altered, fractured and faulted zones which are typical in Japan. The Main Shaft is situated at the fault which strikes to NNW while the Ventilation Shaft at the intact granitic rock. Sub-stages, which connect two shafts were constructed every 100 m depth interval, and several boreholes were drilled and are planned to be drilled from the shafts and the galleries for sampling rocks, groundwater, and for continuous monitoring of <span class="hlt">pore</span> <span class="hlt">pressures</span>. During the construction, we observed transient <span class="hlt">pore</span> <span class="hlt">pressure</span> responses caused by the excavation and dewatering/flooding of the shafts and boreholes. Here, we present one example of the spatio-temporal <span class="hlt">pore</span> <span class="hlt">pressure</span> responses caused by the rapid discharge of groundwater of which amount was 0.5 tons per minute from one pilot borehole. <span class="hlt">Pore</span> <span class="hlt">pressure</span> responses showed two distinct patterns, one continuous decline and the other transient increase and subsequent decline. The former pattern was observed at the locations where <span class="hlt">pore</span> <span class="hlt">pressure</span> transducers were set in the granitic rocks and were situated in the same block with discharge points with respect to the fault with NNW strike, while the latter in sedimentary formations and in the granite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7998332','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7998332"><span>[Emoxipin correction of disorders of lipid peroxidation as affected by a slight <span class="hlt">excess</span> of oxygen <span class="hlt">pressure</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lukash, A I; Vnukov, V V; Prokof'ev, V N; Khodakova, A A; Mogil'nitskaia, L V; Kostenko, E V</p> <p>1994-01-01</p> <p>The role of the emoxipin (Em.) (2-ethyl-6-methyl-3-oxipyridine) in the correction of the free radical oxidation and allied processes in lung tissues and blood plasma under high-<span class="hlt">pressure</span> oxygen-prolonged action has been investigated. The studied oxygen exposure (0.3 MPa, 5h) causes the lung stage of oxygen intoxication. It is confirmed by exterior morphological assessment of the lung. The lipid peroxidation increase in lung tissue and blood plasma as well as erythrocyte membranes destabilization result from oxygen exposure. Lipid peroxidation intensity was estimated by determining of content of lipid peroxidation molecular products such as diene conjugates and Shiffs' bases. Erythrocyte membranes stability was evaluated with hemoglobin yield, total iron level and total peroxidase activity in blood plasma. Emoxipin was injected intraperitoneally in a dose 150 mg per 1 kg rats' weight just before the oxygen exposure. Emoxipin is found to improve physiological state of animals and to increase their survival; it normalizes morphology of the lungs and their state; stabilizes erythrocyte membranes injured under oxygen exposure; decreases intensity of lipid peroxidation processes in the lungs and in blood plasma which was previously increased under hyperoxia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22752877','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22752877"><span><span class="hlt">Excessive</span> zinc intake increases systemic blood <span class="hlt">pressure</span> and reduces renal blood flow via kidney angiotensin II in rats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kasai, Miyoko; Miyazaki, Takashi; Takenaka, Tsuneo; Yanagisawa, Hiroyuki; Suzuki, Hiromichi</p> <p>2012-12-01</p> <p>This study investigated the effects of <span class="hlt">excess</span> zinc intake on the mean arterial <span class="hlt">pressure</span> (MAP), renal blood flow (RBF), inulin clearance (IC), serum zinc level, serum angiotensin-converting enzyme (ACE) activity, and kidney angiotensin II (AT II) levels in rats. Experiments were performed on male Sprague-Dawley rats maintained for 4 weeks on a diet containing either 5 mg/100 g (control group), 50 mg/100 g (Zn50 group), or 200 mg/100 g (Zn200 group) zinc carbonate. Serum zinc levels significantly increased to 126.5 % in the Zn50 group and 198.1 % in the Zn200 group compared with controls. MAP significantly increased to 107.8 % in the Zn50 group and 114.5 % in the Zn200 group again compared with controls. Although the difference in serum ACE activity was independent of the serum zinc levels, the kidney AT II levels increased significantly to 137.2 % in the Zn50 group and 174.4 % in the Zn200 group compared with the controls. RBF was decreased significantly to 74.4 % in the Zn50 group and 69.7 % in the Zn200 group compared with the controls. IC values were significantly decreased to 69.6 % in the Zn50 group and 52.7 % in the Zn200 group as compared with control levels. Combined together, these results show that <span class="hlt">excessive</span> Zn intake reduced IC and RBF and increased MAP and kidney AT II levels, suggesting that <span class="hlt">excessive</span> Zn intake reduces renal function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.S23A2226L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.S23A2226L"><span>Coupling of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Ground Motion Data Recorded During the 2010 El Mayor-Cucapah (Baja California) Earthquake at the NEES@UCSB Wildlife Station</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lavallee, D.; Seale, S. H.; Steidl, J. H.</p> <p>2011-12-01</p> <p><span class="hlt">Pore</span> <span class="hlt">pressure</span> built up during an earthquake and the hazard associated with soil liquefaction present a major challenge for our society, as was dramatically displayed during the 2011 Higashi Nihon Daishinsai (Tohoku-oki, Japan) earthquake. Currently, there is a consensus among scientists that a better assessment of the risk associated with liquefaction requires a better understanding of the coupling between <span class="hlt">pore</span> <span class="hlt">pressure</span> time histories and ground motion time histories. Specifically, there is a basic need to investigate the coupling as a function of the frequency content of the ground motion. The 2010 El Mayor-Cucapah (Baja California) earthquake (M 7.2) provides a remarkable opportunity to undertake such an investigation and lay the basis to model the coupling. The event was well recorded at the NEES@UCSB Wildlife station located 110 km from the hypocenter. The station is equipped with three-component strong-motion accelerometers at the surface and in boreholes at various depths and with <span class="hlt">pore</span> <span class="hlt">pressure</span> transducers located in a saturated, liquefiable layer. The recorded <span class="hlt">pore</span> <span class="hlt">pressure</span> and ground motion time histories are both characterized by a frequency content that is a function of time. A wavelet representation is a natural approach to investigate non-stationary time histories. To study the coupling between two signals we use the following procedure: We first compute the wavelet coefficients associated with the two signals. Then we compute the correlation between the wavelet coefficients of the two signals as a function of the frequency. Correlation coefficients provide information about the degree of linear dependence between the two signals. To account for the presence of multiplicative constants relating the wavelet coefficients of the first signal to the wavelet coefficients of the second signal, we compare the square norm of the wavelet coefficients of the two signals for the available frequency range. Additionally, investigating the distribution of the square</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V41B1722B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V41B1722B"><span>Significance of Dynamic <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Variations - Comparison of Observations on Mud Volcanoes on the Costa Rica Margin and in the Gulf of Cadiz</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brueckmann, W.; Linke, P.; Pieper, M.; Hensen, C.; Tuerk, M.</p> <p>2006-12-01</p> <p>Research in the cooperative research center (SFB) 574 "Volatiles and Fluids in Subduction Zones" at the University Kiel focuses on volatile and fluid exchange processes at subduction zones. These have a significant impact on the long-term geochemical evolution of the hydrosphere and atmosphere. In the SFB 574 working area off Central America more than 120 mud volcanoes, mud diapirs and cold seeps have been identified and sampled. To better understand the internal dynamics of these structures and the temporal variability of fluid expulsion an in-situ tool for monitoring shallow <span class="hlt">pore</span> <span class="hlt">pressure</span> variations was devised. The tool (PWPL) monitors <span class="hlt">pore</span> <span class="hlt">pressure</span> variations along a 2m profile in the shallow subsurface using a stinger with 4 <span class="hlt">pressure</span> ports. Positioned with a video-guided lander the stinger is gently pushed into the seafloor where it remains for several weeks or months in autonomous mode before being retrieved. While particular emphasis was placed on the convergent margin of Central America, mud volcanoes in other tectonic settings suitable for long-term observations of fluid flux are used for comparison. Here we will present data and interpretations from two mud volcanoes off Costa Rica and in the Gulf of Cadiz where we have conducted successful tests. <span class="hlt">Pore</span> <span class="hlt">pressure</span> data from short-term tests on Mound 11 on the continental slope off Costa Rica are compared with new results from a long-term (3-month) campaign on the Captain Arutjunov deep water mud volcano in the Gulf of Cadiz. Rates of fluid flow at both structures have been thoroughly characterized and quantified with geochemical methods providing a frame of reference for judging the significance of dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span> variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH41C1830H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH41C1830H"><span>Seasonal Effects on the Relationships Between Soil Water Content, <span class="hlt">Pore</span> Water <span class="hlt">Pressure</span> and Shear Strength and Their Implications for Slope Stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, P. N.</p> <p>2015-12-01</p> <p>A soil's shear resistance is mainly dependent upon the magnitude of effective stress. For small to medium height slopes (up to 10m) in clay soils the total stress acting along potential failure planes will be low, therefore the magnitude of effective stress (and hence soil shear strength) will be dominated by the <span class="hlt">pore</span>-water <span class="hlt">pressure</span>. The stability of slopes on this scale through periods of increased precipitation is improved by the generation of negative <span class="hlt">pore</span> <span class="hlt">pressures</span> (soil suctions) during preceding, warmer, drier periods. These negative <span class="hlt">pore</span> water <span class="hlt">pressures</span> increase the effective stress within the soil and cause a corresponding increase in shearing resistance. The relationships between soil water content and <span class="hlt">pore</span> water <span class="hlt">pressure</span> (soil water retention curves) are known to be hysteretic, but for the purposes of the majority of slope stability assessments in partially saturated clay soils, these are assumed to be consistent with time. Similarly, the relationship between shear strength and water content is assumed to be consistent over time. This research presents a laboratory study in which specimens of compacted Glacial Till (typical of engineered slopes within the UK) were subjected to repeated cycles of wetting and drying to simulate seasonal cycles. At predetermined water contents, measurements of soil suction were made using tensiometer and dewpoint potentiometer methods. The undrained shear strength of the specimens was then measured using triaxial strength testing equipment. Results indicate that repeated wetting and drying cycles caused a change in the soil water retention behaviour. A reduction in undrained shear strength at corresponding water contents along the wetting and drying paths was also observed. The mechanism for the change in the relationship is believed to be a deterioration in the soil physical structure due to shrink/swell induced micro-cracking. The non-stationarity of these relationships has implications for slope stability assessment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T53B2120S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T53B2120S"><span>Spectral Analysis of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Data Recorded from the 2010 Sierra EL Mayor (baja California) Earthquake at the NEES@UCSB Wildlife Field Site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seale, S. H.; Lavallee, D.; Steidl, J. H.; Ratzesberger, H.; Hegarty, P.</p> <p>2010-12-01</p> <p>On 4 April 2010, the M7.2 Sierra el Mayor event occurred in Baja California, Mexico. The NEES@UCSB Wildlife field site in the Imperial Basin is located 110 km NNW of the hypocenter. The event was recorded on all channels: by three-component strong-motion accelerometers at the surface and in boreholes at various depths and by <span class="hlt">pore</span> <span class="hlt">pressure</span> transducers located in a saturated, liquefiable layer. We have computed the spectra of the <span class="hlt">pore</span> <span class="hlt">pressure</span> response in the frequency domain for signals recorded at different depths. At each depth, the spectrum is attenuated as a power law with a sharp discontinuity at a frequency close to 1 Hz. We report the value of the exponents that characterize the power-law behavior of these spectra. We also computed cross-spectral analysis of the <span class="hlt">pore</span> <span class="hlt">pressure</span> records from different depths. The functional behaviors of the curves of the cross-spectra are similar to that of the original spectra. For comparison, we present the spectrum of each component of the ground motion recorded at a nearby accelerometer. Partially due to the late arrival of the surface waves, the frequency content of the recorded <span class="hlt">pore</span> <span class="hlt">pressure</span> signal is a function of time. To gain a better understanding of the time-dependence of the frequency content, we performed spectral analysis of the signal in a moving window and wavelet transforms of the full signals. The spectral analysis suggests that, except for high frequencies, the curves exhibit a complex behavior as a function of the window position. We interpret and discuss the consequences of the estimated spectra, the cross-spectra, and the wavelet transforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..417D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..417D"><span>Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>, ballistic impacts and shock waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Douillet, Guilhem Amin; Kueppers, Ulrich; Taisne, Benoit; Tsang-Hin-Sun, Ève; Müller, Sebastian K.; Dingwell, Donald B.</p> <p>2015-04-01</p> <p>Dilute pyroclastic density currents (PDCs) represent peculiar transport mechanisms sharing similarities with turbidity currents, wind-blown transport and granular flows. Outcrops of syn-eruptive, soft-sediment deformation are compiled from seven volcanic centers in order to provide a broad perspective on the variety of structures: Ubehebe craters (USA), Tungurahua (Ecuador), Soufrière Hills (Montserrat), Laacher See (Germany), Lago di Albano (Italy), Tower Hill and Purrumbete lake (both Australia). The interpretation of the variety of triggers enlightens the understanding of the sedimentary environment and basal boundary processes for PDCs: 1/ Isolated, cm-scale, overturned beds with vortex forms have been interpreted to be the signature of shear instabilities occurring at the boundary of two granular media. They may represent the frozen record of granular, pseudo Kelvin-Helmholtz instabilities. 2/ The occurrence of degassing pipes together with basal intrusive dikes suggest fluidization during flow stages. This, in turn, can facilitate the development of Kelvin-Helmholtz structures. The occurrence of injection dikes at the base of flow units in some outcrops compared with suction-driven local uplifts in others indicates the role of dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span> and local changes between depletive and accumulative dynamics of flows. 3/ Isolated slumps as well as sinking pseudonodules are driven by their <span class="hlt">excess</span> weight and occur after deposition but penecontemporaneous to the eruption. 4/ Impact of ballistic blocks can trigger local displacement or liquefaction. Based on the deformation depth, these can yield precise insights into depositional unit boundaries. Such impact structures may also be at the origin of some of the steep truncation planes visible at the base of the so-called "chute and pool" structures. 5/ Finally, the passage of shock waves emanating from the vent may be preserved in the form of trains of isolated, fine-grained overturned beds, which may disturb</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SolE....6..553D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SolE....6..553D"><span>Syn-eruptive, soft-sediment deformation of deposits from dilute pyroclastic density current: triggers from granular shear, dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>, ballistic impacts and shock waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Douillet, G. A.; Taisne, B.; Tsang-Hin-Sun, E.; Muller, S. K.; Kueppers, U.; Dingwell, D. B.</p> <p>2015-05-01</p> <p>Soft-sediment deformation structures can provide valuable information about the conditions of parent flows, the sediment state and the surrounding environment. Here, examples of soft-sediment deformation in deposits of dilute pyroclastic density currents are documented and possible syn-eruptive triggers suggested. Outcrops from six different volcanoes have been compiled in order to provide a broad perspective on the variety of structures: Soufriere Hills (Montserrat), Tungurahua (Ecuador), Ubehebe craters (USA), Laacher See (Germany), and Tower Hill and Purrumbete lakes (both Australia). The variety of features can be classified in four groups: (1) tubular features such as pipes; (2) isolated, laterally oriented deformation such as overturned or oversteepened laminations and vortex-shaped laminae; (3) folds-and-faults structures involving thick (>30 cm) units; (4) dominantly vertical inter-penetration of two layers such as potatoids, dishes, or diapiric flame-like structures. The occurrence of degassing pipes together with basal intrusions suggest fluidization during flow stages, and can facilitate the development of other soft-sediment deformation structures. Variations from injection dikes to suction-driven, local uplifts at the base of outcrops indicate the role of dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>. Isolated, centimeter-scale, overturned beds with vortex forms have been interpreted to be the signature of shear instabilities occurring at the boundary of two granular media. They may represent the frozen record of granular, pseudo Kelvin-Helmholtz instabilities. Their recognition can be a diagnostic for flows with a granular basal boundary layer. Vertical inter-penetration and those folds-and-faults features related to slumps are driven by their <span class="hlt">excess</span> weight and occur after deposition but penecontemporaneous to the eruption. The passage of shock waves emanating from the vent may also produce trains of isolated, fine-grained overturned beds that disturb the surface bedding</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010IJEaS..99..227K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010IJEaS..99..227K"><span>Long-term in situ monitoring at Dashgil mud volcano, Azerbaijan: a link between seismicity, <span class="hlt">pore-pressure</span> transients and methane emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kopf, Achim; Delisle, Georg; Faber, Eckhard; Panahi, Behrouz; Aliyev, Chingiz S.; Guliyev, Ibrahim</p> <p>2010-10-01</p> <p>Mud volcanism is a global phenomenon usually associated with compressional tectonics that favour extrusion of fluid- and clay mineral-rich sediment both on land and offshore. Methane, the dominant gas phase, is emitted at variable rates during and after emplacement of the mud domes. In case of continental mud volcanoes, the gas is directly released into the atmosphere, thereby contributing to global warming. Azerbaijan is one of the countries with one of the highest abundances of mud domes globally. One of the most prominent mud volcanoes, Dashgil, has been chosen for a case study because of its historic record of violent eruptions, continued activity, and well-documented regional geology in the Caucasus orogenic wedge adjacent to the Caspian Sea. Since 2003, gas flux has quantitatively measured at one of the two crater lakes and is characterized by valve-type behaviour and episodically violent degassing. In 2007, the large crater lake was additionally equipped with methane fluxmeters as well as an in situ <span class="hlt">pore-pressure</span> probe into the conduit. Our data are complemented by regional seismicity, and exhibit the following results: (1) there seems to be a significant correlation between changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> in the conduit feeding the main crater lake and the rate of gas escape; (2) changes in gas-flux rate appear to be independent of local seismicity, in particular since no larger EQs have been recorded since 2003; (3) despite discontinuous monitoring owing to technical failures, we observe an overall increase in methane emission with time; (4) nearby earthquake activity (<M4.6) can be correlated with <span class="hlt">pore-pressure</span> transients recorded by the piezometer, which reach up to 2.4 kPa compared to the pre-seismic value; (5) from time to time, there are strong lake-level fluctuations decoupled from precipitation or evaporation, which are explained by subbottom hydraulic communication between the two crater lakes and adjacent gryphons. The wealth of observations leads us to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......528M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......528M"><span>Best Practices for Mudweight Window Generation and Accuracy Assessment between Seismic Based <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Prediction Methodologies for a Near-Salt Field in Mississippi Canyon, Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mannon, Timothy Patrick, Jr.</p> <p></p> <p>Improving well design has and always will be the primary goal in drilling operations in the oil and gas industry. Oil and gas plays are continuing to move into increasingly hostile drilling environments, including near and/or sub-salt proximities. The ability to reduce the risk and uncertainly involved in drilling operations in unconventional geologic settings starts with improving the techniques for mudweight window modeling. To address this issue, an analysis of wellbore stability and well design improvement has been conducted. This study will show a systematic approach to well design by focusing on best practices for mudweight window projection for a field in Mississippi Canyon, Gulf of Mexico. The field includes depleted reservoirs and is in close proximity of salt intrusions. Analysis of offset wells has been conducted in the interest of developing an accurate picture of the subsurface environment by making connections between depth, non-productive time (NPT) events, and mudweights used. Commonly practiced petrophysical methods of <span class="hlt">pore</span> <span class="hlt">pressure</span>, fracture <span class="hlt">pressure</span>, and shear failure gradient prediction have been applied to key offset wells in order to enhance the well design for two proposed wells. For the first time in the literature, the accuracy of the commonly accepted, seismic interval velocity based and the relatively new, seismic frequency based methodologies for <span class="hlt">pore</span> <span class="hlt">pressure</span> prediction are qualitatively and quantitatively compared for accuracy. Accuracy standards will be based on the agreement of the seismic outputs to <span class="hlt">pressure</span> data obtained while drilling and petrophysically based <span class="hlt">pore</span> <span class="hlt">pressure</span> outputs for each well. The results will show significantly higher accuracy for the seismic frequency based approach in wells that were in near/sub-salt environments and higher overall accuracy for all of the wells in the study as a whole.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMNH34A..08L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMNH34A..08L"><span>Long-term in situ monitoring at Dashgil mud volcano, Azerbaijan: A link between seismicity, <span class="hlt">pore</span> <span class="hlt">pressure</span> transients and methane emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lange, M.; Kopf, A.; Delisle, G.; Faber, E.; Panahi, B.; Aliyev, C.; Guliyev, I.</p> <p>2009-12-01</p> <p>Mud volcanism is a global phenomenon usually associated with compressional tectonics that favour extrusion of fluid- and clay mineral-rich sediment both on land and offshore. Methane, the dominant gas phase, is emitted at variable rates during and after emplacement of the mud domes. In case of continental mud volcanoes, the gas is directly released into the atmosphere, thereby contributing to global warming. Azerbaijan is one of the countries with one of the highest abundances of mud domes globally. One of the most prominent mud volcanoes, Dashgil, has been chosen for a case study because of its historic record of violent eruptions, continued activity, and well-documented regional geology in the Caucasus orogenic wedge adjacent to the Caspian Sea. Since 2003, gas flux has quantitatively measured at one of the two crater lakes and is characterized by valve-type behaviour and episodically violent degassing. In 2007, the large crater-lake was additionally equipped with methane fluxmeters as well as an in situ <span class="hlt">pore</span> <span class="hlt">pressure</span> probe into the conduit. Our data are complemented by regional seismicity, and exhibit the following results: (1) There seems to be a significant correlation between changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> in the conduit feeding the main crater lake and the rate of gas escape; (2) Changes in gas flux rate appear to be independent of local seismicity, in particular since no larger EQs have been recorded since 2003; (3) Despite discontinuous monitoring owing to technical failures, we observe an overall increase in methane emission with time; (4) Nearby earthquake activity (< M4.6) can be correlated with <span class="hlt">pore</span> <span class="hlt">pressure</span> transients recorded by the piezometer, which reach up to 2.4 kPa compared to the pre-seismic value; (5) From time to time, there are strong lake level fluctuations decoupled from precipitation or evaporation, which are explained by subbottom hydraulic communication between the two crater lakes and adjacent gryphons. The wealth of observations leads us to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1783b0207S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1783b0207S"><span>An influence of normal stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> on the conditions and dynamics of shear crack propagation in brittle solids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shilko, Evgeny V.; Psakhie, Sergey G.; Popov, Valentin L.</p> <p>2016-11-01</p> <p>The paper is devoted to the study of the influence of crack-normal stress on the shear strength of the brittle material with initial crack and the geometrical condition of acceleration of dynamically growing crack towards the longitudinal wave speed. We considered elastic-brittle permeable materials with nanoscale <span class="hlt">pore</span> size. We have shown that <span class="hlt">pore</span> fluid in nanoporous brittle materials influences mainly the condition of shear crack propagation transition from conventional sub-Rayleigh regime to supershear one. The results of the study make it possible to assess the ability of initial cracks in brittle materials to develop in supershear regime under the condition of confined longitudinal shear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1148579','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1148579"><span>Advanced Technologies for Monitoring CO2 Saturation and <span class="hlt">Pore</span> <span class="hlt">Pressure</span> in Geologic Formations: Linking the Chemical and Physical Effects to Elastic and Transport Properties</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mavko, G.; Vanorio, T.; Vialle, S.; Saxena, N.</p> <p>2014-03-31</p> <p>Ultrasonic P- and S-wave velocities were measured over a range of confining <span class="hlt">pressures</span> while injecting CO2 and brine into the samples. <span class="hlt">Pore</span> fluid <span class="hlt">pressure</span> was also varied and monitored together with porosity during injection. Effective medium models were developed to understand the mechanisms and impact of observed changes and to provide the means for implementation of the interpretation methodologies in the field. Ultrasonic P- and S-wave velocities in carbonate rocks show as much as 20-50% decrease after injection of the reactive CO2-brine mixture; the changes were caused by permanent changes to the rock elastic frame associated with dissolution of mineral. Velocity decreases were observed under both dry and fluid-saturated conditions, and the amount of change was correlated with the initial <span class="hlt">pore</span> fabrics. Scanning Electron Microscope images of carbonate rock microstructures were taken before and after injection of CO2-rich water. The images reveal enlargement of the <span class="hlt">pores</span>, dissolution of micrite (micron-scale calcite crystals), and pitting of grain surfaces caused by the fluid- solid chemical reactivity. The magnitude of the changes correlates with the rock microtexture – tight, high surface area samples showed the largest changes in permeability and smallest changes in porosity and elastic stiffness compared to those in rocks with looser texture and larger intergranular <span class="hlt">pore</span> space. Changes to the <span class="hlt">pore</span> space also occurred from flow of fine particles with the injected fluid. Carbonates with grain-coating materials, such as residual oil, experienced very little permanent change during injection. In the tight micrite/spar cement component, dissolution is controlled by diffusion: the mass transfer of products and reactants is thus slow and the fluid is expected to be close to thermodynamical equilibrium with the calcite, leading to very little dissolution, or even precipitation. In the microporous rounded micrite and macropores, dissolution is controlled by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JAG....78...77L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JAG....78...77L"><span>Modeling seismic stimulation: Enhanced non-aqueous fluid extraction from saturated porous media under <span class="hlt">pore-pressure</span> pulsing at low frequencies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lo, Wei-Cheng; Sposito, Garrison; Huang, Yu-Han</p> <p>2012-03-01</p> <p>Seismic stimulation, the application of low-frequency stress-pulsing to the boundary of a porous medium containing water and a non-aqueous fluid to enhance the removal of the latter, shows great promise for both contaminated groundwater remediation and enhanced oil recovery, but theory to elucidate the underlying mechanisms lag significantly behind the progress achieved in experimental research. We address this conceptual lacuna by formulating a boundary-value problem to describe <span class="hlt">pore-pressure</span> pulsing at seismic frequencies that is based on the continuum theory of poroelasticity for an elastic porous medium permeated by two immiscible fluids. An exact analytical solution is presented that is applied numerically using elasticity parameters and hydraulic data relevant to recent proof-of-principle laboratory experiments investigating the stimulation-induced mobilization of trichloroethene (TCE) in water flowing through a compressed sand core. The numerical results indicated that significant stimulation-induced increases of the TCE concentration in effluent can be expected from <span class="hlt">pore-pressure</span> pulsing in the frequency range of 25-100 Hz, which is in good agreement with what was observed in the laboratory experiments. Sensitivity analysis of our numerical results revealed that the TCE concentration in the effluent increases with the porous medium framework compressibility and the pulsing <span class="hlt">pressure</span>. Increasing compressibility also leads to an optimal stimulation response at lower frequencies, whereas changing the pulsing <span class="hlt">pressure</span> does not affect the optimal stimulation frequency. Within the context of our model, the dominant physical cause for enhancement of non-aqueous fluid mobility by seismic stimulation is the dilatory motion of the porous medium in which the solid and fluid phases undergo opposite displacements, resulting in stress-induced changes of the <span class="hlt">pore</span> volume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR41B..07K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR41B..07K"><span>The transition from brittle faulting to thermally-activated cataclasitic flow in sandstone as a function of <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>: Laboratory constrains on the effective <span class="hlt">pressure</span> law at the seismogenic depths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanaya, T.; Hirth, G.</p> <p>2013-12-01</p> <p>Triaxial compression experiments were conducted on intact quartz sandstone with a porosity of 13% at a temperature of 900°C, confining <span class="hlt">pressure</span> (Pc) of 175 MPa, and <span class="hlt">pore</span> <span class="hlt">pressure</span> ratio, λ = Pf / Pc, of 0 to 1 to investigate the roles of <span class="hlt">pore</span> <span class="hlt">pressure</span> (Pf) on the brittle-ductile transitions in the crust. On the basis of σ-ɛ curves, acoustic emissions, ɛ field mapped using an image analysis, and microstructures, three modes of failure are identified as a function of <span class="hlt">pore</span> <span class="hlt">pressure</span>. At 0.28 < λ < 1, brittle faulting occurs at ɛ 1.5-5% with a spontaneous surge in acoustic emission preceded by an accelerating strain-weakening rate, both ɛ11 and ɛ12 localized within <15% of the sample width, and microstructures distinguished by near-fault intragranular fractures. In the absence of the <span class="hlt">pore</span> fluid, the sandstone undergoes thermally-activated cataclasitic flow, involving considerable strain hardening to σ peak ~ 2.5 σ yield, weakening rate dσ/dɛ of -4 GPa, and minor dynamic faulting and diffusive surges in acoustic emission at ɛ 8%. Samples exhibit a reduction in porosity and increase in ɛ11 both by several % throughout the sample, near-fault ɛ12 extended to 40% of the sample width, and pervasive microstructures indicative of shear-enhanced compaction, including intense intragranular fractures, crushed grains, and numerous shear fractures several mm in length and μm in displacement. At 0.06 < λ < 0.15, we observe overall characteristics similar to those in the dry case, except that this transitional mode shows a considerably reduced peak strength of σ peak ~ 1.5 σ yield, weakening rate of -2 GPa, and silent, quasi-static faulting at ɛ 7-9%. Micsrostructures, marked by shear fractures 10 μm both in displacement and thickness and 20% of the sample that retains relatively intact <span class="hlt">pore</span> spaces and unfractured grains, indicate more pronounced shearing and less grain crushing than that in the dry test, likely attributed to smaller shear resistance under reduced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015LPICo1843.8018D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015LPICo1843.8018D"><span>Parameterization of Finite-Element Cryo-Hydrologic Sand Dune Model to Constrain Debris-Flow-Initiating Subsurface Temperatures and <span class="hlt">Pore</span>-Water <span class="hlt">Pressures</span>, Great Kobuk Sand Dunes, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dinwiddie, C. L.; Hooper, D. M.</p> <p>2015-05-01</p> <p>To explain how debris flows form at subfreezing air temperatures, we present meteorology-driven, numerical simulation-derived subsurface temperature and <span class="hlt">pore</span>-water <span class="hlt">pressure</span> profiles in the Great Kobuk Sand Dunes of Alaska, for incipient flow events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28579165','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28579165"><span>Independent influences of <span class="hlt">excessive</span> body weight and elevated blood <span class="hlt">pressure</span> from childhood on left ventricular geometric remodeling in adulthood.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yan, Yinkun; Liu, Junting; Wang, Liang; Hou, Dongqing; Zhao, Xiaoyuan; Cheng, Hong; Mi, Jie</p> <p>2017-09-15</p> <p>Obesity and hypertension are two risk factors of left ventricular hypertrophy (LVH) in adults. We aimed to examine the impacts of body weight and blood <span class="hlt">pressure</span> (BP) from childhood on adult LV geometric remodeling. The study cohort consisted of 1256 adults aged 27-42years who had 2-10 measurements of body mass index (BMI) and BP from childhood in 1987 to adulthood in 2010. We calculated the cumulative and incremental values of BMI and BP from childhood to adulthood. In adulthood, four LV geometric patterns were defined based on the values of left ventricular mass index (g/m(2.7)) and relative wall thickness: normal geometry, concentric remodeling (CR), eccentric hypertrophy (EH) and concentric hypertrophy (CH). The prevalence of abnormal LV geometric patterns in adults was 26.4% for CR, 2.0% for EH and 2.5% for CH. For childhood values, systolic BP (Odds Ratio [OR]=1.26, 95% confidence interval [CI]=1.08-1.47) but not BMI (OR=1.06, 95%CI=0.93-1.18) was associated with adult CR, whereas BMI (OR=3.53, 95%CI=2.09-5.98) but not systolic BP (OR=1.04, 95%CI=0.65-1.66) was associated with adult EH. Both childhood BMI (OR=2.69, 95%CI=1.77-4.09) and systolic BP (OR=1.64, 95%CI=1.07-2.51) were independently associated with adult CH. For adulthood, cumulative and incremental values, BMI and systolic BP were independently associated with adult CR, EH and CH. <span class="hlt">Excessive</span> body weight and elevated BP from childhood have independent influences on the development of adult LV geometric remodeling. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T11E..05L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T11E..05L"><span><span class="hlt">Pore</span> <span class="hlt">Pressure</span> Evolution in Shallow Subduction Earthquake Sequences and Effects on Aseismic Slip Transients -- Numerical Modeling With Rate and State Friction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Y.; Rice, J. R.</p> <p>2005-12-01</p> <p>In 3D modeling of long tectonic loading and earthquake sequences on a shallow subduction fault [Liu and Rice, 2005], with depth-variable rate and state friction properties, we found that aseismic transient slip episodes emerge spontaneously with only a simplified representation of effects of metamorphic fluid release. That involved assumption of a constant in time but uniformly low effective normal stress in the downdip region. As suggested by observations in several major subduction zones [Obara, 2002; Rogers and Dragert, 2003; Kodaira et al, 2004], the presence of fluids, possibly released from dehydration reactions beneath the seismogenic zone, and their <span class="hlt">pressurization</span> within the fault zone may play an important role in causing aseismic transients and associated non-volcanic tremors. To investigate the effects of fluids in the subduction zone, particularly on the generation of aseismic transients and their various features, we develop a more complete physical description of the <span class="hlt">pore</span> <span class="hlt">pressure</span> evolution (specifically, <span class="hlt">pore</span> <span class="hlt">pressure</span> increase due to supply from dehydration reactions and shear heating, decrease due to transport and dilatancy during slip), and incorporate that into the rate and state based 3D modeling. We first incorporated two important factors, dilatancy and shear heating, following Segall and Rice [1995, 2004] and Taylor [1998]. In the 2D simulations (slip varies with depth only), a dilatancy-stabilizing effect is seen which slows down the seismic rupture front and can prevent rapid slip from extending all the way to the trench, similarly to Taylor [1998]. Shear heating increases the <span class="hlt">pore</span> <span class="hlt">pressure</span>, and results in faster coseismic rupture propagation and larger final slips. In the 3D simulations, dilatancy also stabilizes the along-strike rupture propagation of both seismic and aseismic slips. That is, aseismic slip transients migrate along the strike faster with a shorter Tp (the characteristic time for <span class="hlt">pore</span> <span class="hlt">pressure</span> in the fault core to re</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T31F2572K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T31F2572K"><span>Response to long-period seismic waves recorded by broadband seismometer and <span class="hlt">pore</span> <span class="hlt">pressure</span> sensor at IODP Site C0002, Nankai Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitada, K.; Araki, E.; Kimura, T.; Saffer, D. M.</p> <p>2013-12-01</p> <p>Long term in situ monitoring of seismic activity, slow slip event, and <span class="hlt">pore</span> fluid behavior around mega earthquake zone is important for understanding the processes of earthquake generation and strain accumulation. In order to characterize the response to long-period seismic waves, we compared waveforms and hydroseismograms recorded by broadband seismometer and <span class="hlt">pore</span> <span class="hlt">pressure</span> transducers, respectively, which were installed at IODP Site C0002 in the Nankai Trough Kumano Basin. The borehole monitoring system sensor array at Site C0002 is designed to collect multiparameter observations covering a dynamic range of events, including local microearthquakes, low frequency earthquakes, and large-scale earthquakes similar to the Tonankai earthquake. The suite of sensors for the downhole portion of the observatory includes a broadband seismometer (CMG3TBD, Guralp Systems Ltd.) with sampling rate of 100Hz at the depth of 907mbsf, and four <span class="hlt">pressure</span> ports connected to <span class="hlt">pressure</span> gauges located at 948mbsf, 917mbsf, 766mbsf, and at the seafloor. The sampling rate of the data logger was set to 1Hz after successful connection to the DONET seafloor cable network for real-time monitoring on 24 Jan 2013. Since then, we processed 12 earthquakes between a moment magnitude of 6.5 to 8.3. In addition to the comparison of long-period surface waves waveform and <span class="hlt">pressure</span> data, we compared the records with theoretical strain seismograms. The latter were calculated by normal mode summation using the earth model PREM of Dziewonski and Anderson (1981). A Butterworth bandpass filter was applied to the records with cut-off frequencies of 0.003 and 0.1 Hz. Our initial results indicate that the hydroseismograms correspond well with the vertical rather than the horizontal (radial and transverse) components in seismic data. The observed hydroseismogram have a good correlation with the predicted volumetric strain seismogram, especially for the Okhotsk (2013/05/24 14:17UT, Mw8.3, 632km depth), the Chishima</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MMI....23..336K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MMI....23..336K"><span>Effects of particle size and forming <span class="hlt">pressure</span> on <span class="hlt">pore</span> properties of Fe-Cr-Al porous metal by pressureless sintering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koo, Bon-Uk; Yi, Yujeong; Lee, Minjeong; Kim, Byoung-Kee</p> <p>2017-03-01</p> <p>With increased hydrogen consumption in ammonia production, refining and synthesis, fuel cells and vehicle industries, development of the material components related to hydrogen production is becoming an important factor in industry growth. Porous metals for fabrication of hydrogen are commonly known for their relative excellence in terms of large area, lightness, lower heat capacity, high toughness, and permeability. Fe-Cr-Al alloys not only have high corrosion resistance, heat resistance, and chemical stability but also ductility, excellent mechanical properties. In order to control powder size and sintering temperature effects of Fe-Cr-Al porous metal fabrication, Fe-Cr-Al powder was classified into 25-35 μm, 35-45 μm, 45-75 μm using an auto shaking sieve machine and then classified Fe-Cr-Al powders were pressed into disk shapes using a uniaxial press machine and CIP. The pelletized Fe-Cr-Al specimens were sintered at various temperatures in high vacuum. Properties such as <span class="hlt">pore</span> size, porosity, and air permeability were evaluated using perm-porosimetry. Microstructure and phase changes were observed with SEM and XRD. Porosity and relative density were proportionated to increasing sintering temperature. With sufficient sintering at increasing temperatures, the <span class="hlt">pore</span> size is expected to be gradually reduced. Porosity decreased with increasing sintering temperature and gradually increased necking of the powder.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...515056C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...515056C"><span><span class="hlt">Pressure</span>-Induced Amorphization of Small <span class="hlt">Pore</span> Zeolites—the Role of Cation-H2O Topology and Anti-glass Formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A.; Vogt, Thomas; Lee, Yongjae</p> <p>2015-10-01</p> <p>Systematic studies of <span class="hlt">pressure</span>-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li+, Na+, K+, Rb+, Cs+ allow us to assess the role of two different EFC-H2O configurations within the <span class="hlt">pores</span> of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset <span class="hlt">pressure</span> of PIA than the NATII materials containing Rb and Cs as EFC. The onset <span class="hlt">pressure</span> of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under <span class="hlt">pressure</span>. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from <span class="hlt">pressures</span> near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced—this opens a new way to form anti-glass structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4601026','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4601026"><span><span class="hlt">Pressure</span>-Induced Amorphization of Small <span class="hlt">Pore</span> Zeolites—the Role of Cation-H2O Topology and Anti-glass Formation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A.; Vogt, Thomas; Lee, Yongjae</p> <p>2015-01-01</p> <p>Systematic studies of <span class="hlt">pressure</span>-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li+, Na+, K+, Rb+, Cs+ allow us to assess the role of two different EFC-H2O configurations within the <span class="hlt">pores</span> of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset <span class="hlt">pressure</span> of PIA than the NATII materials containing Rb and Cs as EFC. The onset <span class="hlt">pressure</span> of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under <span class="hlt">pressure</span>. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from <span class="hlt">pressures</span> near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced—this opens a new way to form anti-glass structures. PMID:26455345</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/751601','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/751601"><span>A Semi-Empirical <span class="hlt">Excess</span> <span class="hlt">Pressure</span> Equation for CO{sub 2}-H{sub 2}O fluids at 400 C, 0--400 MPa</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Blencoe, J.G.; Anovitz, L.M.; Singh, J.</p> <p>1999-09-12</p> <p>Highly accurate and precise density data for CO{sub 2}-H{sub 2}O mixtures at 400 C 10-400 MPa, were used to develop a modified, B-truncated virial equation for <span class="hlt">excess</span> <span class="hlt">pressure</span> (P{sup ex}). This function and empirical equations of state for H{sub 2}O and CO{sub 2} accurately represent the experimentally determined densities, and interpolate smoothly between data points. Integrating the P{sub ex} expression with respect to molar volume yields an equation for <span class="hlt">excess</span> Helmholta free energy, which can be used to calculate other <span class="hlt">excess</span> properties of interest. The P{sup ex} modeling method has important advantages over more conventional, alternative approaches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JHyd..376..337R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JHyd..376..337R"><span>The effects of wettability and trapping on relationships between interfacial area, capillary <span class="hlt">pressure</span> and saturation in porous media: A <span class="hlt">pore</span>-scale network modeling approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raeesi, Behrooz; Piri, Mohammad</p> <p>2009-10-01</p> <p>SummaryWe use a three-dimensional mixed-wet random <span class="hlt">pore</span>-scale network model to investigate the impact of wettability and trapping on the relationship between interfacial area, capillary <span class="hlt">pressure</span> and saturation in two-phase drainage and imbibition processes. The model is a three-dimensional network of interconnected <span class="hlt">pores</span> and throats of various geometrical shapes. It allows multiple phases to be present in each capillary element in wetting and spreading layers, as well as occupying the center of the <span class="hlt">pore</span> space. Two different random networks that represent the <span class="hlt">pore</span> space in Berea and a Saudi Arabia reservoir sandstone are used in this study. We allow the wettability of the rock surfaces contacted by oil to alter after primary drainage. The model takes into account both contact angle and trapping hystereses. We model primary oil drainage and water flooding for mixed-wet conditions, and secondary oil injection for a water-wet system. The total interfacial area for <span class="hlt">pores</span> and throats are calculated when the system is at capillary equilibrium. They include contributions from the arc menisci (AMs) between the bulk and corner fluids, and from the main terminal menisci (MTMs) between different bulk fluids. We investigate hysteresis in these relationships by performing water injection into systems of varying wettability and initial water saturation. We show that trapping and contact angle hystereses significantly affect the interfacial area. In a strongly water-wet system, a sharp increase is observed at the beginning of water flood, which shifts the area to a higher level than primary drainage. As we change the wettability of the system from strongly water-wet to strongly oil-wet, the trapped oil saturation decreases significantly. Starting water flood from intermediate water saturations, greater than the irreducible water saturation, can also affect the non-wetting phase entrapment, resulting in different interfacial area behaviors. This can increase the interfacial area</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.799a2008Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.799a2008Y"><span>The prediction of helium gas viscosity under high <span class="hlt">pressure</span> and high temperature with the Chapman-Enskog solution and <span class="hlt">excess</span> viscosity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yusibani, Elin; Takata, Yasuyuki; Suud, Zaki; Irwanto, Dwi</p> <p>2017-01-01</p> <p>The purpose of this work is to predict a helium gas viscosity under high <span class="hlt">pressure</span> and high temperature for practical industrial uses. The suitable force constants and a collision integral for the Chapman-Enskog solution to estimate viscosity in the limit of zero density were recommended by the present author. At high density, modification of the Arp and McCarty extrapolation equation for <span class="hlt">excess</span> viscosity was applied. A combination of the Chapman-Enskog solution and modification of the Arp and McCarty <span class="hlt">excess</span> viscosity gives an estimation of helium gas viscosity within 2 to 5 % deviation from the existing experimental data under high-temperature and high-<span class="hlt">pressure</span> region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24821941','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24821941"><span><span class="hlt">Excess</span> <span class="hlt">pressure</span> integral predicts cardiovascular events independent of other risk factors in the conduit artery functional evaluation substudy of Anglo-Scandinavian Cardiac Outcomes Trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Davies, Justin E; Lacy, Peter; Tillin, Therese; Collier, David; Cruickshank, J Kennedy; Francis, Darrel P; Malaweera, Anura; Mayet, Jamil; Stanton, Alice; Williams, Bryan; Parker, Kim H; McG Thom, Simon A; Hughes, Alun D</p> <p>2014-07-01</p> <p><span class="hlt">Excess</span> <span class="hlt">pressure</span> integral (XSPI), a new index of surplus work performed by the left ventricle, can be calculated from blood <span class="hlt">pressure</span> waveforms and may indicate circulatory dysfunction. We investigated whether XSPI predicted future cardiovascular events and target organ damage in treated hypertensive individuals. Radial blood <span class="hlt">pressure</span> waveforms were acquired by tonometry in 2069 individuals (aged, 63±8 years) in the Conduit Artery Functional Evaluation (CAFE) substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT). Measurements of left ventricular mass index (n=862) and common carotid artery intima media thickness (n=923) were also performed. XSPI and the integral of reservoir <span class="hlt">pressure</span> were lower in people treated with amlodipine±perindopril than in those treated with atenolol±bendroflumethiazide, although brachial systolic blood <span class="hlt">pressure</span> was similar. A total of 134 cardiovascular events accrued during a median 3.4 years of follow-up; XSPI was a significant predictor of cardiovascular events after adjustment for age and sex, and this relationship was unaffected by adjustment for conventional cardiovascular risk factors or Framingham risk score. XSPI, central systolic blood <span class="hlt">pressure</span>, central augmentation <span class="hlt">pressure</span>, central pulse <span class="hlt">pressure</span>, and integral of reservoir <span class="hlt">pressure</span> were correlated with left ventricular mass index, but only XSPI, augmentation <span class="hlt">pressure</span>, and central pulse <span class="hlt">pressure</span> were associated positively with carotid artery intima media thickness. Associations between left ventricular mass index, XSPI, and integral of reservoir <span class="hlt">pressure</span> and carotid artery intima media thickness and XSPI were unaffected by multivariable adjustment for other covariates. XSPI is a novel indicator of cardiovascular dysfunction and independently predicts cardiovascular events and targets organ damage in a prospective clinical trial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16853191','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16853191"><span>Storage of hydrogen at 303 K in graphite slitlike <span class="hlt">pores</span> from grand canonical Monte Carlo simulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kowalczyk, Piotr; Tanaka, Hideki; Hołyst, Robert; Kaneko, Katsumi; Ohmori, Takumi; Miyamoto, Junichi</p> <p>2005-09-15</p> <p>Grand canonical Monte Carlo (GCMC) simulations were used for the modeling of the hydrogen adsorption in idealized graphite slitlike <span class="hlt">pores</span>. In all simulations, quantum effects were included through the Feynman and Hibbs second-order effective potential. The simulated surface <span class="hlt">excess</span> isotherms of hydrogen were used for the determination of the total hydrogen storage, density of hydrogen in graphite slitlike <span class="hlt">pores</span>, distribution of <span class="hlt">pore</span> sizes and volumes, enthalpy of adsorption per mole, total surface area, total <span class="hlt">pore</span> volume, and average <span class="hlt">pore</span> size of pitch-based activated carbon fibers. Combining experimental results with simulations reveals that the density of hydrogen in graphite slitlike <span class="hlt">pores</span> at 303 K does not exceed 0.014 g/cm(3), that is, 21% of the liquid-hydrogen density at the triple point. The optimal <span class="hlt">pore</span> size for the storage of hydrogen at 303 K in the considered <span class="hlt">pore</span> geometry depends on the <span class="hlt">pressure</span> of storage. For lower storage <span class="hlt">pressures</span>, p < 30MPa, the optimal <span class="hlt">pore</span> width is equal to a 2.2 collision diameter of hydrogen (i.e., 0.65 nm), whereas, for p congruent with 50MPa, the <span class="hlt">pore</span> width is equal to an approximately 7.2 collision diameter of hydrogen (i.e., 2.13 nm). For the wider <span class="hlt">pores</span>, that is, the <span class="hlt">pore</span> width exceeds a 7.2 collision diameter of hydrogen, the surface <span class="hlt">excess</span> of hydrogen adsorption is constant. The importance of quantum effects is recognized in narrow graphite slitlike <span class="hlt">pores</span> in the whole range of the hydrogen <span class="hlt">pressure</span> as well as in wider ones at high <span class="hlt">pressures</span> of bulk hydrogen. The enthalpies of adsorption per mole for the considered carbonaceous materials are practically constant with hydrogen loading and vary within the narrow range q(st) congruent with 7.28-7.85 kJ/mol. Our systematic study of hydrogen adsorption at 303 K in graphite slitlike <span class="hlt">pores</span> gives deep insight into the timely problem of hydrogen storage as the most promising source of clean energy. The calculated maximum storage of hydrogen is equal to approximately 1.4 wt</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24808049','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24808049"><span>Zinc-<span class="hlt">Excess</span> Intake Causes the Deterioration of Renal Function Accompanied by an Elevation in Systemic Blood <span class="hlt">Pressure</span> Primarily Through Superoxide Radical-Induced Oxidative Stress.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yanagisawa, Hiroyuki; Miyazaki, Takashi; Nodera, Makoto; Miyajima, Yuka; Suzuki, Takashi; Kido, Takamasa; Suka, Machi</p> <p>2014-07-01</p> <p>Using rats fed 22 g/d of a control diet containing 0.005% zinc (Zn) or 2 Zn-<span class="hlt">excess</span> diets containing 0.05% or 0.2% Zn for 4 weeks, we examined the mechanisms involved in the deterioration of renal function induced by Zn-<span class="hlt">excess</span> intake. An increase in Zn intake elevated mean blood <span class="hlt">pressure</span> (BP) and reduced renal blood flow (RBF) and inulin clearance in a dose-dependent manner. This decline in inulin clearance may be derived from a fall in RBF. Administration of the nitric oxide (NO) synthase inhibitor, N(ω)-nitro-l-arginine methyl ester, markedly increased mean BP and significantly decreased RBF in the 3 groups of rats. Administration of the exogenous superoxide radical (OO(-)) scavenger, tempol, significantly decreased mean BP and substantially increased RBF in all groups of rats. These observations suggest that both an elevation in systemic BP and a reduction in RBF seen in the 2 Zn-<span class="hlt">excess</span> diet groups result from a decrease in the action of the vasodilator, NO, through the formation of peroxynitrite based on the nonenzymatic reaction of NO and increased OO(-) Indeed, the activity of the endogenous OO(-) scavenger, copper/Zn-superoxide dismutase, was significantly reduced in the vessel wall of rats fed 2 Zn-<span class="hlt">excess</span> diets versus a control diet. 8-Hydroxy-2'-deoxyguanosine formation caused by OO(-) generation was notably elevated in the kidneys of rats fed 2 Zn-<span class="hlt">excess</span> diets relatively to rats fed a control diet. Thus, Zn-<span class="hlt">excess</span> intake leads to the aggravation of renal function concomitantly with an increase in systemic BP predominantly through the oxidative stress caused by OO(). © The Author(s) 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSM.V41B..02F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.V41B..02F"><span>How changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> affect fluid circulation in volcanoes: three examples from Vulcano Island, Mt. Etna and Mt Vesuvius (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Federico, C.; Madonia, P.; Capasso, G.; D'Alessandro, W.; Bellomo, S.; Brusca, L.; Cusano, P.; Longo, M.; Paonita, A.; Petrosino, S.</p> <p>2013-05-01</p> <p>Fluids circulating in volcanic edifices are attracting increasing interest from scientists, mostly because their role in triggering flank instability, phreatic explosions, and eruptions has been documented in several cases worldwide [Newhall et al. 2001, Thomas et al. 2004]. Fluid <span class="hlt">pore</span> <span class="hlt">pressure</span> can change as an effect of either external (meteoric recharge, variation of the stress field), or endogenous causes (e.g. internal <span class="hlt">pressurization</span> of magmatic volatiles and hydrothermal systems). The reciprocal roles of tectonics and magmatic/hydrothermal activity are still under investigation [Gottsman et al. 2007, Roeloffs et al. 2003]. We discuss the results of decennial data records collected in the aquifers of Mt Etna, Vulcano Island and Mt Vesuvius, and get insights on the role of tectonics and volcanic activity on the observed variations of water level and chemical composition. In Vulcano Island, the shallow thermal aquifer is deeply concerned by deep volcanic fluids. The most significant variations were observed during the 1988-96 crisis, due to the large input of steam and acidic gases from depth. In addition, the record of the water table elevation provided remarkable insights on the <span class="hlt">pressure</span> of the volcano-hydrothermal system, which can be envisaged as the cause for the onset of the phase of higher vapor output in the fumarolic field in late 2004. On Mt. Vesuvius, the geochemical behavior of the aquifer appears strictly controlled by the input of volcanic gases and variations in the stress field. These latter, which were responsible for the seismic crisis of 1999, and the almost simultaneous increased input of CO2-rich vapor, significantly affected water chemistry and temperature, until 2006. The recent observations of low salinity, temperature, and dissolved carbon contents in groundwater provide strong evidence for reduced <span class="hlt">pressure</span> in the volcano-hydrothermal system. The record of water chemistry available on Mt. Etna since 1994 shows coeval changes in almost all</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNG13A1871G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNG13A1871G"><span>Veins in Paleo-reservoir as a Natural Indication of Coupled Changes in <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Stress, Salt Wash Graben of SE Utah, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gwon, S.; Edwards, P.; Kim, Y. S.</p> <p>2015-12-01</p> <p>Hydrofracturing associated with elevated fluid <span class="hlt">pressure</span> coupled with changes in stress has been crucial in enhancing the production and recovery of hydrocarbons. Furthermore, it is also an important issue to access the efficiency and stability of long-term CO2 geologic storage reservoirs. Veins are mineral-filled extension fractures developed along the plane of σ1-σ2 and perpendicular to σ3, and the fluid <span class="hlt">pressure</span> must exceed σ3applied to the plane when the vein opens. Therefore, vein is a well-known natural analogue for fluid migration in a paleo-reservoir. In the Salt Wash Graben of SE Utah, CO2-charged vein systems hosted in the bleached Entrada Formation are well developed and examined to understand the conditions of fluid <span class="hlt">pressure</span> and stress during the injections of CO2-charged fluid. Based on color and relative cross-cutting relationship in the field, veins are subdivided into two sets; sub-vertical black mineral-rich veins and orthogonal calcite veins that have previously been described as 'grid-lock fractures'. The vein distribution and fluid leakage along through-going fractures in mechanic units allow us to determine the stress regime and driving stress condition through 3D-Mohr circle reconstruction. The results of this statistical analysis for the veins show that the orthogonal veins indicate a 'stress transition' with maximum principal stress direction changing from vertical to NNW-SSE sub-horizontal which coincides with the current regional stress regime. The possible causes of the stress transition can be considered. The process of repeated sealing, reactivation and localization of veins within the bleached zone is a natural indication of a coupled change in <span class="hlt">pore</span> <span class="hlt">pressure</span> and stress in the reservoir. Thus, an understanding of the effect of stress changes due to the volumetric injection of CO2 in the subsurface as well as a knowledge of how pre-existing fractures affect fluid flow with respect to elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> in layered rocks are</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.7374D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.7374D"><span>The 2003-2004 seismic swarm in the western Corinth rift: Evidence for a multiscale <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion process along a permeable fault system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duverger, Clara; Godano, Maxime; Bernard, Pascal; Lyon-Caen, Hélène; Lambotte, Sophie</p> <p>2015-09-01</p> <p>Microseismic multiplets occurring in the western Corinth rift, Greece, during a large swarm are analyzed to retrieve their spatiotemporal characteristics. These multiplets activated small subfaults at depth (˜7 km), up to 1 km long, at the root of two parallel active normal faults. The swarm migrates westward nearly horizontally over 10 km at an average velocity of 50 m/d with a diffusivity of 0.5 m2 s-1. It successively activates the Aigion fault, a relay zone in its hanging wall, and the Fassouleika fault. Within each multiplet, hypocenters also migrate with diffusivities ranging from 0.001 to 0.4 m2 s-1. The largest internal diffusivities appear at the core of the layer defined by the clusters. These results are interpreted as a hydroshear process caused by <span class="hlt">pore</span> <span class="hlt">pressure</span> migration within permeable corridors resulting from the intersection of the major faults with a brittle geological layer inherited from the Hellenic nappe stack.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PIAHS.372..533M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PIAHS.372..533M"><span>Land subsidence, seismicity and <span class="hlt">pore</span> <span class="hlt">pressure</span> monitoring: the new requirements for the future development of oil and gas fields in Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Macini, P.; Mesini, E.; Panei, L.; Terlizzese, F.</p> <p>2015-11-01</p> <p>The Emilia earthquake of 2012 (Italy) stimulated a controversial debate concerning the possibility that the event could have been induced or triggered by underground fluids production. The public discussion led the Italian Government to issue a protocol of guidelines for the monitoring of microseismic activity, ground deformation and reservoir <span class="hlt">pore</span> <span class="hlt">pressure</span>. The guidelines will be put into operation as soon as practicable when licensing is being considered, and all data provided by mining operators must be made available to the relevant Authorities. The implementation of an outreach and communication program to local residents and administrative authorities is prescribed, so that the civil and scientific community at large can gain confidence that operations are being managed optimally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S13B2823K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S13B2823K"><span>Numerical Models of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Stress Changes along Basement Faults due to Wastewater Injection: Applications to Potentially Induced Seismicity in Southern Kansas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koltermann, C.; Hearn, E. H.</p> <p>2015-12-01</p> <p>As hydrocarbon extraction techniques that generate large volumes of wastewater have come into widespread use in the central United States, increased volumes have been injected into deep disposal wells, with a corresponding dramatic increase in seismicity rates. South-central Kansas is of particular scientific interest because fluid injection rates have recently increased due to renewed gas and oil production from the Mississippi Lime Play, and the local seismicity is being monitored with a seismometer network deployed by the USGS. In addition, since only a small percentage of injection wells seem to induce seismicity, it is important to characterize contributing factors. We have developed groundwater flow models using MODFLOW-USG to (1) assess hydrogeologic conditions under which seismicity may be triggered, for cases in which wastewater is injected into sedimentary strata overlying fractured crystalline basement rock and to (2) explore the possible relationship between wastewater injection and the November 2014 M 4.8 Milan, Kansas earthquake. The USG version of MODFLOW allows us to use unstructured meshes, which vastly reduces computation time while allowing dense meshing near injection wells and faults. Our single-well test model has been benchmarked to published models (Zhang et al., 2013) and will be used to evaluate sensitivity <span class="hlt">pore</span> <span class="hlt">pressures</span> and stresses to model parameters. Our south Kansas model represents high-rate injection wells, as well as oil and gas wells producing from the Arbuckle and overlying Mississippian formations in a 40-km square region. Based on modeled <span class="hlt">pore</span> <span class="hlt">pressure</span> and stress changes along the target fault, we will identify conditions that would be consistent with inducing an earthquake at the Milan hypocenter. Parameters to be varied include hydraulic properties of sedimentary rock units, crystalline basement and the fault zone, as well as the (poorly resolved) Milan earthquake hypocenter depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5126630','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5126630"><span>Research of CO2 and N2 Adsorption Behavior in K-Illite Slit <span class="hlt">Pores</span> by GCMC Method</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chen, Guohui; Lu, Shuangfang; Zhang, Junfang; Xue, Qingzhong; Han, Tongcheng; Xue, Haitao; Tian, Shansi; Li, Jinbu; Xu, Chenxi; Pervukhina, Marina; Clennell, Ben</p> <p>2016-01-01</p> <p>Understanding the adsorption mechanisms of CO2 and N2 in illite, one of the main components of clay in shale, is important to improve the precision of the shale gas exploration and development. We investigated the adsorption mechanisms of CO2 and N2 in K-illite with varying <span class="hlt">pore</span> sizes at the temperature of 333, 363 and 393 K over a broad range of <span class="hlt">pressures</span> up to 30 MPa using the grand canonical Monte Carlo (GCMC) simulation method. The simulation system is proved to be reasonable and suitable through the discussion of the impact of cation dynamics and <span class="hlt">pore</span> wall thickness. The simulation results of the <span class="hlt">excess</span> adsorption amount, expressed per unit surface area of illite, is in general consistency with published experimental results. It is found that the sorption potential overlaps in micropores, leading to a decreasing <span class="hlt">excess</span> adsorption amount with the increase of <span class="hlt">pore</span> size at low <span class="hlt">pressure</span>, and a reverse trend at high <span class="hlt">pressure</span>. The <span class="hlt">excess</span> adsorption amount increases with increasing <span class="hlt">pressure</span> to a maximum and then decreases with further increase in the <span class="hlt">pressure</span>, and the decreasing amount is found to increase with the increasing <span class="hlt">pore</span> size. For <span class="hlt">pores</span> with size greater larger than 2 nm, the overlap effect disappears. PMID:27897232</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...637579C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...637579C"><span>Research of CO2 and N2 Adsorption Behavior in K-Illite Slit <span class="hlt">Pores</span> by GCMC Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Guohui; Lu, Shuangfang; Zhang, Junfang; Xue, Qingzhong; Han, Tongcheng; Xue, Haitao; Tian, Shansi; Li, Jinbu; Xu, Chenxi; Pervukhina, Marina; Clennell, Ben</p> <p>2016-11-01</p> <p>Understanding the adsorption mechanisms of CO2 and N2 in illite, one of the main components of clay in shale, is important to improve the precision of the shale gas exploration and development. We investigated the adsorption mechanisms of CO2 and N2 in K-illite with varying <span class="hlt">pore</span> sizes at the temperature of 333, 363 and 393 K over a broad range of <span class="hlt">pressures</span> up to 30 MPa using the grand canonical Monte Carlo (GCMC) simulation method. The simulation system is proved to be reasonable and suitable through the discussion of the impact of cation dynamics and <span class="hlt">pore</span> wall thickness. The simulation results of the <span class="hlt">excess</span> adsorption amount, expressed per unit surface area of illite, is in general consistency with published experimental results. It is found that the sorption potential overlaps in micropores, leading to a decreasing <span class="hlt">excess</span> adsorption amount with the increase of <span class="hlt">pore</span> size at low <span class="hlt">pressure</span>, and a reverse trend at high <span class="hlt">pressure</span>. The <span class="hlt">excess</span> adsorption amount increases with increasing <span class="hlt">pressure</span> to a maximum and then decreases with further increase in the <span class="hlt">pressure</span>, and the decreasing amount is found to increase with the increasing <span class="hlt">pore</span> size. For <span class="hlt">pores</span> with size greater larger than 2 nm, the overlap effect disappears.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS21A1607F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS21A1607F"><span>Methane hydrate <span class="hlt">pore</span> saturation evaluation from geophysical logging and <span class="hlt">pressure</span> core analysis, at the first offshore production test site in the eastern Nankai Trough, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, T.; Suzuki, K.; Takayama, T.; Konno, Y.; Yoneda, J.; Egawa, K.; Ito, T.; Nagao, J.</p> <p>2013-12-01</p> <p>On March 2013, the first offshore production test form methane hydrate (MH) concentrated zone (MHCZ) was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21) at the AT1 site located in the north-western slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. Before the production test, extensive geophysical logging and <span class="hlt">pressure</span> coring using Hybrid <span class="hlt">Pressure</span> Coring System were conducted in 2012 at monitoring well (AT1-MC) and coring well (AT1-C), in order to obtain basic information for the MH reservoir characterization. MH <span class="hlt">pore</span> saturation (Sh) is one of the important basic parameters not only for reservoir characterization, but also the resource assessment. However, precise evaluation of Sh from geophysical logging is still challenging technical issue. The MHCZ confirmed by the geophysical logging at AT1-MC has a turbidite assemblage (from several tens of centimeters to a few meters) with 60 m of gross thickness; it is composed of lobe/sheet type sequences in the upper part, and relatively thick channel sand sequences in the lower part. In this study, the Sh evaluated from geophysical logging data were compared with those evaluated from <span class="hlt">pressure</span> core analysis. Resistivity logs and nuclear magnetic resonance (NMR) log were used for the Sh evaluation by geophysical logging. Standard Archie equation was applied for Sh evaluation from resistivity log, while density magnetic resonance (DMR) method was used for Sh evaluation from NMR log. The Sh from <span class="hlt">pressure</span> core samples were evaluated using the amount of dissociated gas volume, together with core sample bulk volume, measured porosity, net sand intervals, and assumed methane solubility in <span class="hlt">pore</span> water. In the upper part of the MHCZ, Sh estimated from resistivity log showed distinct difference in value between sand and mud layers, compared to Sh from NMR log. Resistivity log has higher vertical resolution than NMR log, so it is favorable for these kinds of thin bed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22369098','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22369098"><span>Direct measurements of <span class="hlt">pore</span> fluid density by vibrating tube densimetry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gruszkiewicz, Miroslaw S; Rother, Gernot; Wesolowski, David J; Cole, David R; Wallacher, Dirk</p> <p>2012-03-20</p> <p>The densities of <span class="hlt">pore</span>-confined fluids were measured for the first time by means of vibrating tube densimetry (VTD). A custom-built high-<span class="hlt">pressure</span>, high-temperature vibrating tube densimeter was used to measure the densities of propane at subcritical and supercritical temperatures (between 35 and 97 °C) and carbon dioxide at supercritical temperatures (between 32 and 50 °C) saturating hydrophobic silica aerogel (0.2 g/cm(3), 90% porosity) synthesized inside Hastelloy U-tubes. Additionally, supercritical isotherms of <span class="hlt">excess</span> adsorption for CO(2) and the same porous solid were measured gravimetrically using a precise magnetically coupled microbalance. <span class="hlt">Pore</span> fluid densities and total adsorption isotherms increased monotonically with increasing density of the bulk fluid, in contrast to <span class="hlt">excess</span> adsorption isotherms, which reached a maximum and then decreased toward zero or negative values above the critical density of the bulk fluid. The isotherms of confined fluid density and <span class="hlt">excess</span> adsorption obtained by VTD contain additional information. For instance, the maxima of <span class="hlt">excess</span> adsorption occur below the critical density of the bulk fluid at the beginning of the plateau region in the total adsorption, marking the end of the transition of <span class="hlt">pore</span> fluid to a denser, liquidlike <span class="hlt">pore</span> phase. Compression of the confined fluid significantly beyond the density of the bulk fluid at the same temperature was observed even at subcritical temperatures. The effect of <span class="hlt">pore</span> confinement on the liquid-vapor critical temperature of propane was less than ~1.7 K. The results for propane and carbon dioxide showed similarity in the sense of the principle of corresponding states. Good quantitative agreement was obtained between <span class="hlt">excess</span> adsorption isotherms determined from VTD total adsorption results and those measured gravimetrically at the same temperature, confirming the validity of the vibrating tube measurements. Thus, it is demonstrated that vibrating tube densimetry is a novel experimental</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1033163','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1033163"><span>Direct Measurements of <span class="hlt">Pore</span> Fluid Density by Vibrating Tube Densimetry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gruszkiewicz, Miroslaw {Mirek} S; Rother, Gernot; Wesolowski, David J; Cole, David R; Wallacher, Dirk</p> <p>2012-01-01</p> <p>The densities of <span class="hlt">pore</span>-confined fluids were measured for the first time by means of a vibrating tube method. Isotherms of total adsorption capacity were measured directly making the method complementary to the conventional gravimetric or volumetric/piezometric adsorption techniques, which yield the <span class="hlt">excess</span> adsorption (the Gibbsian surface <span class="hlt">excess</span>). A custom-made high-<span class="hlt">pressure</span>, high-temperature vibrating tube densimeter (VTD) was used to measure the densities of subcritical and supercritical propane (between 35 C and 97 C) and supercritical carbon dioxide (between 32 C and 50 C) saturating hydrophobic silica aerogel (0.2 g/cm3, 90% porosity) synthesized inside Hastelloy U-tubes. Additionally, <span class="hlt">excess</span> adsorption isotherms for supercritical CO2 and the same porous solid were measured gravimetrically using a precise magnetically-coupled microbalance. <span class="hlt">Pore</span> fluid densities and total adsorption isotherms increased monotonically with increasing density of the bulk fluid, in contrast to <span class="hlt">excess</span> adsorption isotherms, which reached a maximum at a subcritical density of the bulk fluid, and then decreased towards zero or negative values at supercritical densities. Compression of the confined fluid significantly beyond the density of the bulk liquid at the same temperature was observed at subcritical temperatures. The features of the isotherms of confined fluid density are interpreted to elucidate the observed behavior of <span class="hlt">excess</span> adsorption. The maxima of <span class="hlt">excess</span> adsorption were found to occur below the critical density of the bulk fluid at the conditions corresponding to the beginning of the plateau of total adsorption, marking the end of the transition of <span class="hlt">pore</span> fluid to a denser, liquid-like <span class="hlt">pore</span> phase. The results for propane and carbon dioxide showed similarity in the sense of the principle of corresponding states. No measurable effect of <span class="hlt">pore</span> confinement on the liquid-vapor critical point was found. Quantitative agreement was obtained between <span class="hlt">excess</span> adsorption isotherms determined</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23666376','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23666376"><span><span class="hlt">Excessive</span> negative venous line <span class="hlt">pressures</span> and increased arterial air bubble counts during miniaturized cardiopulmonary bypass: an experimental study comparing miniaturized with conventional perfusion systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aboud, Anas; Liebing, Kai; Börgermann, Jochen; Ensminger, Stephan; Zittermann, Armin; Renner, Andre; Hakim-Meibodi, Kavous; Gummert, Jan</p> <p>2014-01-01</p> <p>Miniaturized cardiopulmonary bypass (MCPB) is increasingly used in cardiac surgery, because it can lower clinically significant complications such as systemic inflammatory response, haemolysis and high transfusion requirements. A limitation of MCPB is the risk of <span class="hlt">excessive</span> negative <span class="hlt">pressure</span> in the venous line during volume depletion, probably leading to gaseous microembolism. In an experimental study with 24 pigs, we compared conventional open cardiopulmonary bypass (CCPB group, n = 11) with MCPB (n = 13). The same pump and identical tubing materials were used in both groups. Primary endpoints were <span class="hlt">pressure</span> values in the venous line and the right atrium as well as the amount of air bubbles >500 µm. Secondary endpoints were biochemical parameters of systemic inflammatory response, ischaemia, haemodilution and haemolysis. Nearly 20% of venous <span class="hlt">pressure</span> values were below -150 mmHg and approximately 10% of the right atrial <span class="hlt">pressure</span> values were below -100 mmHg in the MCPB group, during the experiment. No such low values were observed in the CCPB group. In addition, the number of large arterial air bubbles was higher in the MCPB group compared with the CCPB group (mean ± standard deviation [SD]: 13 444 ± 5709 vs 0.9 ± 0.6, respectively; P < 0.001). Bubble volume was also significantly larger during MCPB compared with CCPB (mean ± SD: 1522 ± 654 vs 4.1 ± 2.5 µl, respectively; P < 0.001). Blood levels of interleukin-6, free haemoglobin and creatine kinase were significantly higher in the CCPB group compared with the MCPB group. Despite the benefits of MCPB regarding systemic inflammatory response and haemolysis, this technique is associated with <span class="hlt">excessive</span> negative venous line <span class="hlt">pressures</span> and a significant increase in the number and volume of arterial air bubbles compared with CCPB. Mini-perfusion systems and the management of MCPB require further refinements to avoid such adverse effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/44950','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/44950"><span>Relationships between <span class="hlt">pore</span> <span class="hlt">pressure</span>, stresses, and present-day geodynamics in the Scotian Shelf, offshore eastern Canada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yassir, N.A.; Bell, J.S.</p> <p>1994-12-01</p> <p>A geomechanical study of the Mesozoic and Tertiary sediments beneath the Scotian Shelf shows that two major weak layers exist at depth: the over-<span class="hlt">pressured</span> unit at 4000 m and the basal Argo salt, which is ductile and diapiric. A consistent relationships is observed between the overpressures and the stress state in the basin. First, the smaller horizontal principal stress increases dramatically just above the onset of overpressuring, and secondly, borehole breakouts, indicators of stress anisotropy-decrease in abundance within the overpressure zone. Neither tectonic shear nor rapid burial can explain these observations; however, overpressuring by fluid generation will result in horizontal stress increase and eventually lead to an isotropic stress state. Compelling evidence is found for hydrocarbon generation being a key cause of overpressuring in the Scotian Shelf.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T31G2598Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T31G2598Z"><span>Long Term Observations of Subsurface <span class="hlt">Pore</span> <span class="hlt">Pressure</span> in the Kumano Basin and Upper Accretionary Wedge along the NanTroSIEZE Transect, offshore Japan: Signals from the 2011 Tohoku Earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; Saffer, D. M.</p> <p>2013-12-01</p> <p>Subsurface <span class="hlt">pore</span> <span class="hlt">pressure</span> as a sensitive measure of strain and formation properties has provided insights into the wide range of fault slip behaviors, contributing to the understanding of fault and earthquake mechanics. <span class="hlt">Pore</span> <span class="hlt">pressures</span> from off shore borehole observatory are especially important, as 1) they are the only detectable signals of small and slow events; 2) they provide our only access to the outer forearc, where the tsunami hazards are triggered by the fault slip. As part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) a suite of borehole sensors were installed as part of a long-term borehole observatory at IODP Site C0002, during IODP Expedition # 332 in December of 2010. The observatory includes a broadband seismometer, short period geophones, a volumetric strainmeter, temperature sensors, an accelerometer, and formation <span class="hlt">pore</span> <span class="hlt">pressure</span> monitoring at two depths: one in the mudstones of the Kumano Basin in an interval spanning 757-780 meters below seafloor (mbsf), and a second in the uppermost accretionary wedge in an interval from 937 - 980 mbsf. Here, we report on <span class="hlt">pore</span> <span class="hlt">pressure</span> records acquired at a sampling frequency of 1/60 Hz, spanning the period from December 2010 to January 2013, which were recovered in early 2013. We observe a clear hydraulic signal from March 11, 2011 Tohoku earthquake and aftershocks, including both dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span> changes during passage of surface waves and shifts in formation <span class="hlt">pressure</span> following the event. <span class="hlt">Pressure</span> exhibit an increase of ~3 kPa in the upper sediment screened interval following the earthquake, and decrease by ~5 kPa in the accretionary prism interval. Both of the offset changes persist through the end of the data recording. These <span class="hlt">pore</span> <span class="hlt">pressure</span> changes may reflect static stress changes from the earthquake, or local site effects related to shaking. We also observe a clear increase in formation <span class="hlt">pore</span> <span class="hlt">pressures</span> associated with drilling operations at nearby holes in November and December 2012. These</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T21E2873I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T21E2873I"><span>Seaward- Versus Landward-Verging Thrusts in Accretionary Wedges: A Numerical Modeling Study of the Effects of Heterogeneity in <span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span> and Frictional Strength</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ito, G.; Moore, G. F.; Olive, J. A. L.; Weiss, J. R.</p> <p>2015-12-01</p> <p>Whereas seaward-verging thrust faults are, by far, the most common large faults associated with accretionary wedges, the importance of the globally rare, landward verging thrusts has recently been highlighted given the prominence of landward vergence along the Cascadia margin as well as along the Andaman-Sumatra subduction zone, especially in the rupture area of the great 2004 earthquake. The mechanical processes that lead to seaward- versus landward-verging thrusts in accretionary wedges has long been a topic of debate. A weak frictional décollement is one explanation that indeed promotes landward vergence, but not only so, because the typical pattern is of dual verging conjugate faults. A non-brittle, ductile décollement is a second explanation that has been shown in the laboratory to produce a wide sequence of only landward-verging thrusts, but the mechanical causes are not well understood and numerical modeling studies have yet to reproduce this behavior. A seaward-dipping backstop is a third explanation; it promotes landward vergence locally, but more distally the backstop effects diminish and the sense of vergence transitions back to seaward. Mohr-Coulomb and minimum work theory predict that landward vergence should predominate when the direction of maximum principal compression dips landward. We hypothesize that such a condition can arise due to the migration of <span class="hlt">pore</span> fluids and the associated spatial heterogeneity in frictional strength within the wedge. We test this hypothesis using 2-D numerical models that use a finite-difference, particle-in-cell method for simulating the deformation of an accretionary wedge with a viscoelastic-plastic rheology. With a uniform internal frictional strength, the calculations reproduce many of the faulting behaviors seen in prior laboratory and numerical modeling studies. We are exploring the impacts of heterogeneity in <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and frictional strength on the pattern and vergence of thrust faults.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR33A2634M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR33A2634M"><span>Correlation between <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> and DInSAR post-seismic deformation of the May 20, 2012 Emilia-Romagna (Italy) earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moro, M.; Stramondo, S.; Albano, M.; Barba, S.; Solaro, G.; Saroli, M.; Bignami, C.</p> <p>2015-12-01</p> <p>The present work focuses on the detection and analysis of the postseismic surface deformations following the two earthquakes that hit the Emilia Romagna region (Italy) on May 20 and 29, 2012. The 2012 Emilia earthquake sequence struck the central sector of the Ferrara arc, which represents the external fold-and-thrust system of the Northern Apennines thrust belt buried below the Po plain. The May 20 event occurred on the Ferrara basal thrust at depth, at about 6-7 km, while, during the May 29 event, the rupture jumped on an inner splay of the Ferrara system. The analysis of the postseismic displacements was carried out thanks to a dataset of SAR COSMO­ SkyMed images covering a time span of about one year (May 20, 2012 - May 11, 2013) after the May 20 event. The DInSAR results revealed the presence of two deformation patches: the first one is located in the area that experienced the coseismic uplift. Here the postseismic displacements point out a further ground uplift occurring along the first three months after the 20 May event. The second deformation patch is located in the villages of San Carlo and Mirabello, where ground subsidence lasting about four months was detected. We hypothesized that both the observed phenomena are related to the <span class="hlt">pore</span> <span class="hlt">pressure</span> perturbation caused by the coseismic deformation. In particular, the ground uplift is due to the deep crustal deformations caused by the <span class="hlt">pore</span> fluid diffusion at depth to re-establish the initial hydrostatic stresses. Instead, the ground subsidence is related to the compaction of the shallow sandy layers caused by the liquefaction phenomena, which widely affected the San Carlo and Mirabello area. Preliminary numerical analyses performed with the Finite Element Method and empirical relations confirmed our hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoJI.194..383S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoJI.194..383S"><span>Elastic anisotropy and <span class="hlt">pore</span> space geometry of schlieren granite: direct 3-D measurements at high confining <span class="hlt">pressure</span> combined with microfabric analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Staněk, Martin; Géraud, Yves; Lexa, Ondrej; Špaček, Petr; Ulrich, Stanislav; Diraison, Marc</p> <p>2013-07-01</p> <p><span class="hlt">Pore</span> space geometry of granitic rocks and its evolution with depth are key factors in large-scale seismics or in projects of enhanced geothermal systems or of deep hazardous waste repositories. In this study, we studied macroscopically anisotropic schlieren-bearing granite by experimental P-wave velocity (VP) measurements on spherical sample in 132 directions at seven different confining <span class="hlt">pressures</span> in the range 0.1-400 MPa. In order to discriminate the phenomena affecting the rock elastic properties we analysed the orientation of microcracks and of grain boundaries and we measured the anisotropy of magnetic susceptibility of the rock. Three sets of microcracks were defined, with two of them linked to the massif exfoliation process and one to cooling contraction of the massif. During <span class="hlt">pressurization</span> the measured mean VP and VP anisotropy degree at ambient <span class="hlt">pressure</span> and at highest confinement (400 MPa) yielded 3.3 km s-1 and 24 per cent, and 6.2 km s-1 and 3 per cent, respectively. The associated VP anisotropy pattern was transversely isotropic and governed by the schlieren, with a minimum VP direction perpendicular to them and a girdle of high VP directions parallel to them. The highest change in VP was observed between 0.1 and 10 MPa, suggesting a significant closure of porosity below depths of 500 m. Change of the VP anisotropy pattern to orthorhombic together with increase of mean VP and VP anisotropy degree during depressurization was attributed to inelastic response of one of the sets of microcracks to the loading-unloading cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28581758','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28581758"><span>Molecular Gibbs Surface <span class="hlt">Excess</span> and CO2-Hydrate Density Determine the Strong Temperature- and <span class="hlt">Pressure</span>-Dependent Supercritical CO2-Brine Interfacial Tension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ji, Jiayuan; Zhao, Lingling; Tao, Lu; Lin, Shangchao</p> <p>2017-06-29</p> <p>In CO2 geological storage, the interfacial tension (IFT) between supercritical CO2 and brine is critical for the storage capacitance design to prevent CO2 leakage. IFT relies not only on the interfacial molecule properties but also on the environmental conditions at different storage sites. In this paper, supercritical CO2-NaCl solution systems are modeled at 343-373 K and 6-35 MPa under the salinity of 1.89 mol/L using molecular dynamics simulations. After computing and comparing the molecular density profile across the interface, the atomic radial distribution function, the molecular orientation distribution, the molecular Gibbs surface <span class="hlt">excess</span> (derived from the molecular density profile), and the CO2-hydrate number density under the above environmental conditions, we confirm that only the molecular Gibbs surface <span class="hlt">excess</span> of CO2 molecules and the CO2-hydrate number density correlate strongly with the temperature- and <span class="hlt">pressure</span>-dependent IFTs. We also compute the populations of two distinct CO2-hydrate structures (T-type and H-type) and attribute the observed dependence of IFTs to the dominance of the more stable, surfactant-like T-type CO2-hydrates at the interface. On the basis of these new molecular mechanisms behind IFT variations, this study could guide the rational design of suitable injecting environmental <span class="hlt">pressure</span> and temperature conditions. We believe that the above two molecular-level metrics (Gibbs surface <span class="hlt">excess</span> and hydrate number density) are of great fundamental importance for understanding the supercritical CO2-water interface and engineering applications in geological CO2 storage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H33B1315Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H33B1315Z"><span>Multi-Layer, Sharp-Interface Models of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Buildup within the Illinois Basin due to Basin-Wide CO2 Injection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; Person, M. A.; Gable, C. W.; Celia, M. A.; Nordbotten, J. M.; Bandilla, K.; Elliot, T. R.; Rupp, J.; Ellett, K. M.; Bowen, B.; Pickett, W.; Woolsey, E. E.</p> <p>2011-12-01</p> <p>We recently developed and applied a new parallel, multi-layer, finite-element model to the Illinois Basin in order to assess the spatial extent and magnitude of <span class="hlt">pore</span> <span class="hlt">pressure</span> increases resulting from the annual projected injection of 100 million metric tons of CO2. One focus of this work is to assess the potential for inducing a seismic event associated with low effective stress conditions around CO2 injection wells in the southern Illinois Basin where Mt Simon permeability is relatively low (< 50 mD). We used a sharp-interface formulation to represent a CO2, freshwater, and brine transport within each layer. A simple parallelization scheme was used in which fluid transport in each layer is solved on a separate processor. The layers are linked at the after each time step through vertical fluxes of fresh and saline water across their respective confining units. This model was validated, in part, by comparison to computed <span class="hlt">pore</span> <span class="hlt">pressure</span> distributions from a published 8-layer test case. Our Illinois Basin model represents spatial variations in porosity using a modified form of Athy's law. Permeability is logarithmically related to porosity so that permeability. Principal reservoirs represented in our model include the Mt. Simon Formation, the Knox Dolomite, Ordovician carbonates, Silurian-Devonian and Mississippian-Pennsylvanian sandstone/carbonates units. Key confining unit represented include the Eau Claire, Maquoketa, and New Albany Shales. A limited number of low-permeability faults were also included in the model. The permeability of fault elements were set to between 10-100 times lower than surrounding sediments. We calibrated our model using historical freshwater pumping data from the Chicago area (128 million gallons per day of H2O) as well as the salinity distribution across the Illinois Basin. We found that incorporating a stream network which included the Rock River near Chicago was important in reproducing pre-development head patterns in the Cambro</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.7620Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.7620Z"><span>Correlation between gas permeability and <span class="hlt">pore</span> structure of coal matrix</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, J.; Yang, J.; Gao, F.; Li, Y.; Niu, H.; Gao, H.</p> <p>2012-04-01</p> <p>The sequestration of CO2 in unminable coal seams represents a promising option for CO2 geologic storage, because the injected CO2 may enhance coalbed methane recovery (CO2-ECBM), which could partly offset the costs of the storage process. The CO2-ECBM technology is based on the relative affinity of CO2 and CH4 to coals under given <span class="hlt">pressure</span> and temperature conditions. The <span class="hlt">excess</span> sorption capacity of coals for CO2 is generally higher than the sorption capacity for methane. The coal seams are characterized by a dual porosity structure including cleat and matrix <span class="hlt">pores</span>. The cleats in the coal seams are considered as highways for gas and water flow, while the matrix is the storage location of gas by adsorption. The slow transport process of gas in coal matrix may constrain the efficiency of the displacement of CH4 by CO2 due to the compacted <span class="hlt">pore</span> structure of the coal matrix. Therefore, a detailed understanding of the correlation between permeability of gas and <span class="hlt">pore</span> structure in coal matrix is crucial for the CO2-ECBM processes. Yangquan coals originating from the Qingshui basin, which contains gas-rich coals in China, were selected for the tests in this study. Yangquan coals are classified as anthracite. In order to avoid the influence of coal cleats on fluid flow, small coal plugs (~6 mm in diameter, ~13 mm in length) were selected and fixed in the sample compartment by special glue. A test system for simultaneously measuring adsorption-porosity-permeability on the coal matrix blocks in its free state is constructed. The permeability of gas and porosity in coal plugs to He under different gas <span class="hlt">pressure</span> and temperature conditions were simultaneously investigated. The permeability and <span class="hlt">excess</span> sorption capacity of the coal plugs to He, N2, CH4 and CO2 were compared at a constant gas <span class="hlt">pressure</span> and temperature. It is expected that gas break through a cleat-plug is much faster than that through a coal matrix-plug. Different sample plugs with the different <span class="hlt">pore</span> structure results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EPJWC..5604003S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EPJWC..5604003S"><span>Characterizing the effects of elevated temperature on the air void <span class="hlt">pore</span> structure of advanced gas-cooled reactor <span class="hlt">pressure</span> vessel concrete using x-ray computed tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stein, R. C.; Petkovski, M.; Engelberg, D. L.; Leonard, F.; Withers, P. J.</p> <p>2013-07-01</p> <p>X-ray computed tomography (X-ray CT) has been applied to nondestructively characterise changes in the microstructure of a concrete used in the <span class="hlt">pressure</span> vessel structure of Advanced Gas-cooled Reactors (AGR) in the UK. Concrete specimens were conditioned at temperatures of 105 °C and 250 °C, to simulate the maximum thermal load expected to occur during a loss of coolant accident (LOCA). Following thermal treatment, these specimens along with an unconditioned control sample were characterised using micro-focus X-ray CT with a spatial resolution of 14.6 microns. The results indicate that the air void <span class="hlt">pore</span> structure of the specimens experienced significant volume changes as a result of the increasing temperature. The increase in the porous volume was more prevalent at 250 °C. Alterations in air void size distributions were characterized with respect to the unconditioned control specimen. These findings appear to correlate with changes in the uni-axial compressive strength of the conditioned concrete.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T43D..02T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T43D..02T"><span><span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span> and State of Stress Above the Plate Interface from Observations in a 3 Kilometer Deep Borehole: IODP Site C0002, Nankai Trough Subduction Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tobin, H. J.; Saffer, D. M.; Hirose, T.; Castillo, D. A.; Kitajima, H.; Sone, H.</p> <p>2014-12-01</p> <p>During IODP Expedition 348 from October 2013 to January 2014, Site C0002 was drilled to more than 3000 meters' depth into the inner accretionary wedge at the Nankai Trough, setting a new depth record for scientific ocean drilling. It is the first hole to access the deep interior of an active convergent margin. Site C0002 is part of the NanTroSEIZE project off the Kii-Kumano region of Japan, designed to shed light on plate boundary fault zone processes near the up-dip edge of seismogenic locking and slip. The zone from 865 - 3056 meters below the sea floor was sampled via logging-while-drilling measurements, continuous sampling of drill cuttings, and limited coring. This interval was composed of lithified middle to late Miocene hemipelagic sediments and turbidites that are markedly deformed and dip steeply. P-wave speeds from sonic logs increase with depth to ~ 1600 meters, but are constant to slightly decreasing with depth from 1600 to 3050 meters. We hypothesize that this change in trend indicates the onset of elevated <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>, but structural and lithologic factors may also play a role. We explore several methods for quantitative estimation of sonic-derived fluid <span class="hlt">pressure</span> conditions in the inner wedge. A borehole leak-off test (LOT) and a series of borehole <span class="hlt">pressurization</span> and injection tests were also performed, which we synthesize to estimate the least principal stress, or Shmin. Furthermore, downhole <span class="hlt">pressure</span> while drilling (PWD) measurements recorded during borehole packoff events provide information on the maximum principal stress, SHmax. Taken together, the LOT and PWD observations suggest that the inner wedge at ~ 2000 meters depth is currently in a strike-slip stress regime, despite its position as the hanging wall of a main plate boundary thrust. This may be a transitional stress regime between shallow normal and deep thrust, controlled by depth-dependent magnitude of the tectonic convergence-related principal stress. Our results document for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GGG....16.1089L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.1089L"><span>The impact of splay faults on fluid flow, solute transport, and <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution in subduction zones: A case study offshore the Nicoya Peninsula, Costa Rica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lauer, Rachel M.; Saffer, Demian M.</p> <p>2015-04-01</p> <p>Observations of seafloor seeps on the continental slope of many subduction zones illustrate that splay faults represent a primary hydraulic connection to the plate boundary at depth, carry deeply sourced fluids to the seafloor, and are in some cases associated with mud volcanoes. However, the role of these structures in forearc hydrogeology remains poorly quantified. We use a 2-D numerical model that simulates coupled fluid flow and solute transport driven by fluid sources from tectonically driven compaction and smectite transformation to investigate the effects of permeable splay faults on solute transport and <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution. We focus on the Nicoya margin of Costa Rica as a case study, where previous modeling and field studies constrain flow rates, thermal structure, and margin geology. In our simulations, splay faults accommodate up to 33% of the total dewatering flux, primarily along faults that outcrop within 25 km of the trench. The distribution and fate of dehydration-derived fluids is strongly dependent on thermal structure, which determines the locus of smectite transformation. In simulations of a cold end-member margin, smectite transformation initiates 30 km from the trench, and 64% of the dehydration-derived fluids are intercepted by splay faults and carried to the middle and upper slope, rather than exiting at the trench. For a warm end-member, smectite transformation initiates 7 km from the trench, and the associated fluids are primarily transmitted to the trench via the décollement (50%), and faults intercept only 21% of these fluids. For a wide range of splay fault permeabilities, simulated fluid <span class="hlt">pressures</span> are near lithostatic where the faults intersect overlying slope sediments, providing a viable mechanism for the formation of mud volcanoes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T33F..05O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T33F..05O"><span>Time-dependent wellbore breakout growth caused by drilling-induced <span class="hlt">pore</span> <span class="hlt">pressure</span> transients: Implications for estimations of far field stress magnitude</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olcott, K. A.; Saffer, D. M.; Elsworth, D.</p> <p>2013-12-01</p> <p>One method used to constrain principal stress orientations and magnitudes in the crust combines estimates of rock strength with observations of wellbore failures, including drilling-induced tensile fractures (DITF) and compressional borehole breakouts (BO). This method has been applied at numerous Integrated Ocean Drilling Program (IODP) boreholes drilled into sediments in a wide range of settings, including the Gulf of Mexico, the N. Japan and Costa Rican subduction margins, and the Nankai Trough Accretionary Prism. At Nankai and N. Japan, BO widths defined by logging-while-drilling (LWD) resistivity images have been used to estimate magnitudes of far-field horizontal tectonic stresses. At several drillsites (C0010, C0002, and C0011), sections of the borehole were relogged with LWD after the hole was left open for times ranging from ~30 min to 3 days; times between acquisition were associated with pipe connections (~30 min), cleaning and circulating the hole (up to ~3 hr), and evacuation of the site for weather (~3 days). Relogged portions exhibit widening of BO, hypothesized to reflect time-dependent re-equilibration of instantaneous changes in <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> (Pf) induced by opening the borehole. In this conceptual model, Pf decrease caused by initial excavation of the borehole and resulting changes in the state of stress at the borehole wall lead to an initial strengthening of the sediment. Re-equilibration of Pf results in time-dependent weakening of the sediment and subsequent BO growth. If correct, this hypothesis implies that stress magnitudes estimated by BO widths could be significantly underestimated. We test this idea using a finite-element model in COMSOL multiphysics that couples fluid flow and deformation in a poroelastic medium. We specify far-field horizontal principal stresses (SHmax and Shmin) in the model domain. At the start of simulations/at the time of borehole opening, we impose a decreased stress at the borehole wall. We consider a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22338742','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22338742"><span>Case oriented approach to co-occurrence of risk lifestyle behavior with overweight, <span class="hlt">excess</span> abdominal fat and high blood <span class="hlt">pressure</span>: the CroHort study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brborović, Ognjen; Rukavina, Tea Vukusić; Fazlić, Hana; Vuletić, Silvije; Kern, Josipa; Pavleković, Gordana</p> <p>2012-01-01</p> <p>Objective of this paper is to estimate interim risk factors (INTF) proportions and changes within 5-years of groups with at least one risk health behavior (BEHF) in CroHort population. Results show that CroHort 2008 group has higher proportions of <span class="hlt">excess</span> abdominal fat and overweight. Men older than 65 without any BEHF have smaller proportions of INTF in 2008 than in 2003. Proportion of people with high blood <span class="hlt">pressure</span> is smaller in 2008 for all groups except for young women who show increase. Analysis of middle age group shows significant increase in all INTF in women smokers while men smokers have the highest increase in abdominal fat. Physical inactivity in women is associated with increase of all INTF, while men have decrease in overweight INTF. Alcohol intake has protective effect on middle aged men, except for increase in waist circumference. Women show constant increase in all INTF with heavy alcohol intake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912617T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912617T"><span>Fast fluid-flow events within a subduction-related vein system in oceanic eclogite: implications for <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> at the plate interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taetz, Stephan; John, Timm; Bröcker, Michael; Spandler, Carl; Stracke, Andreas</p> <p>2017-04-01</p> <p> been completed within ca. 3 years. The short-lived, pulse-like character of this process is in accordance with the notion that fluid flow related to oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> increases at the plate interface which may trigger slip events reported from many subduction zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V13E..08M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V13E..08M"><span>Evaluation of <span class="hlt">Pore</span> Networks in Caprocks at Geologic Storage Sites: A Combined Study using High Temperature and <span class="hlt">Pressure</span> Reaction Experiments, Small Angle Neutron Scattering, and Focused Ion Beam-Scanning Electron Microscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mouzakis, K. M.; Sitchler, A.; Wang, X.; McCray, J. E.; Kaszuba, J. P.; Rother, G.; Dewers, T. A.; Heath, J. E.</p> <p>2011-12-01</p> <p>Low permeability rock units, often shales or mudstones, that overlie geologic formations under consideration for CO2 sequestration will help contain injected CO2. CO2 that does flow through these rocks will dissolve into the porewaters, creating carbonic acid lowering the pH. This perturbation of the system may result in mineral dissolution or precipitation, which can change the <span class="hlt">pore</span> structure and impact the flow properties of the caprocks. In order to investigate the impacts that reaction can have on caprock <span class="hlt">pore</span> structure, we performed a combination of high <span class="hlt">pressure</span> high temperature reaction experiments, small angle neutron scattering (SANS) experiments and high resolution focused ion beam-scanning electron microscope (FIB-SEM) imaging on samples from the Gothic shale and Marine Tuscaloosa Group. Small angle neutron scattering was performed on unreacted and reacted caprocks at the High Flux Isotope Reactor at Oak Ridge National Laboratory. New precipitates and <span class="hlt">pores</span> are observed in high-resolution images of the reacted samples. The precipitates have been preliminarily identified as gypsum or anhydrite, and sulfide minerals. Results from small angle neutron scattering, a technique that provides information about <span class="hlt">pores</span> and <span class="hlt">pore</span>/mineral interfaces at scales ~ 5 to 300 nm, show an increased porosity and specific surface area after reaction with brine and CO2. However, there appear to be differences in how the <span class="hlt">pore</span> networks change between the two samples that are related to sample mineralogy and original <span class="hlt">pore</span> network structure. Changes to <span class="hlt">pores</span> and formation of new <span class="hlt">pores</span> may lead to different capillary sealing behavior and permeability. This combination of controlled laboratory experiments, neutron scattering and high-resolution imaging provides detailed information about the geochemical processes that occur at the <span class="hlt">pore</span> scale as CO2 reacts with rocks underground. Such information is integral to the evaluation of large-scale CO2 sequestration as a feasible technology</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2898837','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2898837"><span><span class="hlt">Excessive</span> Tanning</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sansone, Lori A.</p> <p>2010-01-01</p> <p><span class="hlt">Excessive</span> tanning appears to be evident in about one quarter of regular sunbathers. Susceptible individuals are likely to be young Caucasians from Western societies. Despite ongoing education by the media to the public about the risks of <span class="hlt">excessive</span> exposure to ultraviolet radiation and the availability of potent sunscreens, there seems to be a concurrent proliferation of tanning facilities. What might be potential psychological explanations for <span class="hlt">excessive</span> or pathological tanning? Psychopathological explanations may exist on both Axes I and II and include substance use, obsessive-compulsive, body dysmorphic, and borderline personality disorders. While there is no known treatment for pathological sunbathing, we discuss several treatment interventions from the literature that have been successfully used for the general public. PMID:20622941</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28701669','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28701669"><span>Muscle Weakness Is Associated With an Increase of Left Ventricular Mass Through <span class="hlt">Excessive</span> Blood <span class="hlt">Pressure</span> Elevation During Exercise in Patients With Hypertension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kamada, Yumi; Masuda, Takashi; Tanaka, Shinya; Akiyama, Ayako; Nakamura, Takeshi; Hamazaki, Nobuaki; Okubo, Michihito; Kobayashi, Naoyuki; Ako, Junya</p> <p>2017-08-03</p> <p>Autonomic imbalance in hypertension induces <span class="hlt">excessive</span> blood <span class="hlt">pressure</span> (BP) elevation during exercise, thereby increasing left ventricular mass (LVM). Although muscle weakness enhances autonomic imbalance by stimulating muscle sympathetic activity during exercise, it is unclear whether muscle weakness is associated with an increase of LVM in patients with hypertension. This study aimed to investigate the relationships between muscle weakness, BP elevation during exercise, and LVM in these patients. Eighty-six hypertensive patients aged 69 ± 8 years with controlled resting BP (ie, < 140/90 mmHg) were recruited. Plasma brain natriuretic peptide (BNP), left ventricular mass index (LVMI), and knee extension muscle strength were measured. Changes in plasma noradrenaline (NORA) and brachial-ankle pulse wave velocity (ba-PWV) were assessed before and after an ergometer exercise test performed at moderate intensity (ΔNORA and ΔPWV, respectively). A difference between baseline and peak systolic BP during the exercise test was defined as BP elevation during exercise (ΔSBP). Relationships between muscle strength, ΔNORA, ΔPWV, ΔSBP, BNP, and LVMI were analyzed, and significant factors increasing LVM were identified using univariate and multivariate regression analyses. Muscle strength was negatively correlated with ΔNORA (r = -0.202, P = 0.048), ΔPWV (r = -0.328, P = 0.002), ΔSBP (r = -0.230, P = 0.033), BNP (r = -0.265, P = 0.014), and LVMI (r = -0.233, P = 0.031). LVMI was positively correlated with ΔPWV (r = 0.246, P = 0.023) and ΔSBP (r = 0.307, P = 0.004). Muscle strength was a significant independent factor associated with LVMI (β = -0.331, P = 0.010). Our findings suggest that muscle weakness is associated with an increase of LVM through <span class="hlt">excessive</span> BP elevation during exercise in patients with hypertension.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28232594','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28232594"><span>Long-term <span class="hlt">Excessive</span> Body Weight and Adult Left Ventricular Hypertrophy Are Linked Through Later Life Body Size and Blood <span class="hlt">Pressure</span>: The Bogalusa Heart Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Huijie; Zhang, Tao; Li, Shengxu; Guo, Yajun; Shen, Wei; Fernandez, Camilo; Harville, Emily W; Bazzano, Lydia A; Urbina, Elaine M; He, Jiang; Chen, Wei</p> <p>2017-02-23</p> <p>Rationale: Childhood adiposity is associated with cardiac structure in later life, but little is known regarding to what extent childhood body weight affects adult left ventricular geometric patterns through adult body size and blood <span class="hlt">pressure</span> (BP). Objective: Determine quantitatively the mediation effect of adult body weight and BP on the association of childhood BMI with adult left ventricular hypertrophy (LVH). Methods and Results: This longitudinal study consisted of 710 adults, age 26 to 48 years, who had been examined for BMI and BP measured 4 or more times during childhood and 2 or more times during adulthood, with a mean follow-up period of 28.0 years. After adjusting for age, race and sex, adult BMI had a significant mediation effect (76.4%, p<0.01) on the childhood BMI-adult LV mass index (LVMI) association. The mediation effects of adult systolic BP (SBP, 15.2%), long-term burden (12.1%) and increasing trends of SBP (7.9%) were all significant (p<0.01). Furthermore, these mediators also had significant mediation effects on the association of childhood BMI with adult LVH, eccentric and concentric hypertrophy. Importantly, the mediation effects of adult BMI were all significantly stronger than those of adult SBP on LVMI, LVH and LV remodeling patterns (p<0.01). Additionally, the mediation effect of SBP on concentric hypertrophy was significantly stronger than on eccentric hypertrophy (p<0.01). Conclusions: These findings suggest that increased childhood BMI has long-term adverse impact on subclinical changes in adult cardiac structure, and early life <span class="hlt">excessive</span> body weight and adult LVH are linked through later life <span class="hlt">excessive</span> body weight and elevated BP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24881662','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24881662"><span>Usefulness of <span class="hlt">pressure</span>-sensitive adhesives as a pretreatment material before application of topical drug formulations and a peeling tape for <span class="hlt">excess</span> stratum corneum layers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kikuchi, Keisuke; Todo, Hiroaki; Sugibayashi, Kenji</p> <p>2014-01-01</p> <p>Two unique <span class="hlt">pressure</span>-sensitive adhesive (PSA) tapes (PSA-A, -B) with different adhesive properties of commercial PSAs were prepared and evaluated for their usefulness as a pretreatment material prior to the application of transdermal therapeutic systems or topical drug formulations and also as a peeling agent against <span class="hlt">excess</span> layers of the stratum corneum. In the present study, in vitro permeation experiments were conducted using vertical type diffusion cells and excised hairless rat or porcine skin from which the stratum corneum had been stripped several times with PSAs. The results obtained revealed that PSA-A and -B had higher stripping or peeling effects than those of the marketed PSAs. Marked changes were observed in skin barrier function before and after stripping using PSAs, and the enhancement effect on the skin permeation of drugs achieved by stripping the stratum corneum was markedly different between the PSAs. PSA-A, in particular, markedly improved skin permeation and the skin concentration of topically applied chemical compounds because it removed many layers of the stratum corneum when skin was stripped only a few times. In contrast, when PSA-B was used to pretreat the skin surface, the extent of skin permeation and concentration of drugs was safely increased because only a few layers of the stratum corneum were removed, even with repeated stripping. The enhancement effect achieved by PSA-B was not as high as that by PSA-A. Thus, stripping with PSA-A can be used as a penetration enhancement tool, whereas PSA-B can be used as a peeling material against <span class="hlt">excess</span> layers of the stratum corneum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJWC.14009046Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJWC.14009046Z"><span>Study of <span class="hlt">pore</span> fluid effect on the mobility of granular debris flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Gordon G. D.; Sun, Q. C.</p> <p>2017-06-01</p> <p>Granular debris flows in nature are composed of a wide range of solids and viscous <span class="hlt">pore</span> fluids, moving at high velocities down sloping channels. The <span class="hlt">pore</span> fluids in a granular debris flow affect the interactions between the solid and fluid phases and thus govern the debris-flow mobility. Study of the <span class="hlt">pore</span> fluid effect (i.e., <span class="hlt">excess</span> <span class="hlt">pore</span> water <span class="hlt">pressures</span> correlated to solid structures, and the viscous shearing and dragging) is essential for understanding the high flow mobility of granular debris flows. This study critically reviews two dimensionless numbers with clear physical meanings, then demonstrates a new application of field monitoring data for identifying natural debris flows on large scales (i.e., surge and continuous debris-flows, respectively). This study illustrates that, the <span class="hlt">pore</span> fluid viscous shearing stress dominates solid inertial stress due to solids collision. It is also found that different to continuous debris-flows, the high <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> generated in surge debris-flow body dissipate quite slowly and mostly influence particle contact behaviour significantly. A new scientific criterion for identification of continuous and surge debris flow in nature can be given by this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013DPS....4550106M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013DPS....4550106M"><span>Does Extension Play a Role in Ionian Tectonics? Potential Effects of Preexisting Bounding Faults, Local Brittle Failure, and Sulfur <span class="hlt">Pore</span> <span class="hlt">Pressure</span> on Crustal Stresses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McKinnon, William B.; Kirchoff, M.; Bland, M.</p> <p>2013-10-01</p> <p>The majority of mountains observed on Io are tectonic, upthrusted blocks. Their formation is generally thought to be related to Io’s heat-pipe volcanism, crustal subsidence, and accompanying lateral confinement. In previous work, we demonstrated that compressional thermal stresses from sustained local or regional shut down of Io’s heat-pipe volcanism could also play a vital role in mountain formation, and help explain the anticorrelation between Io’s mountains and volcanic centers [Kirchoff and McKinnon 2009, Formation of mountains on Io: Variable volcanism and thermal stresses, Icarus 201, 598-614; Kirchoff et al. 2011, Global distribution of volcanoes and mountains on Io: Control by asthenospheric heating and implications for mountain formation, Earth Planet. Sci. Lett. 301, 22-30]. Here we refine our previous model by using an “unconfined” horizontal boundary condition (zero average lateral stress), including brittle failure (crustal plasticity), and adding sulfur to our rheological model. The unconfined horizontal boundary condition accounts for stresses released on preexisting, more distant faults; including crustal plasticity allows us to more realistically represent stresses that would exceed the brittle failure limit otherwise, and addition of sulfur to the model composition of Io’s crust further improves the rheological model of the crust. Heated and melted at depth, liquid sulfur creates <span class="hlt">pore</span> <span class="hlt">pressure</span> in the lower crust and profoundly reduces the brittle failure limit. Including these modifications when the volcanic eruption rate decreases introduces a region of tensional failure in the upper crust and increases the size of the region in compressional failure in the lower crust. Finite element models show that increasing compression at depth imparts substantial bending stresses, which can drive surface faulting and block rotation. Such conditions further facilitate mountain formation at the surface, and highlight the difference between Io</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1237858','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1237858"><span><span class="hlt">Excess</span> flow shutoff valve</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Kiffer, Micah S.; Tentarelli, Stephen Clyde</p> <p>2016-02-09</p> <p><span class="hlt">Excess</span> flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a <span class="hlt">pressure</span> difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The <span class="hlt">pressure</span> difference exceeds a target <span class="hlt">pressure</span> difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12461472','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12461472"><span>The impact of callosities on the magnitude and duration of plantar <span class="hlt">pressure</span> in patients with diabetes mellitus. A callus may cause 18,600 kilograms of <span class="hlt">excess</span> plantar <span class="hlt">pressure</span> per day.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pataky, Z; Golay, A; Faravel, L; Da Silva, J; Makoundou, V; Peter-Riesch, B; Assal, J P</p> <p>2002-11-01</p> <p>The importance of high peak plantar <span class="hlt">pressure</span> (PP) in the development of foot ulcer is well known. However, few studies have analyzed the real impact of callosities on plantar <span class="hlt">pressure</span> and ulcer formation. The plantar <span class="hlt">pressure</span> (PP) in patients with diabetes mellitus was studied in three groups, of a total number of 33 type 2 diabetic patients, without neuropathy or peripheral vascular disease: subjects with callus (A) (n = 10), subjects without callus (B) (n = 10), and a separate group of patients with callus which was submitted to callus removal (C) (n = 13). The plantar <span class="hlt">pressure</span> (PP) parameters were measured by FSR 174 sensors and computer analyses were performed by LabView. Both maximum peak PP and duration of PP are significantly higher in patients with callus (peak PP: 314 +/- 52 kPa vs 128 +/- 16 kPa, p < 0.005; duration of PP: 621 +/- 27 ms vs 505 +/- 27 ms, p < 0.05). The intervention group C before and after callus removal showed an identical trend. Callus removal has decreased the peak PP by 58% (p < 0.001) and duration of PP has been decreased by 150 milliseconds by step (p < 0.05). This study has shown the deleterious role of callus and assuming that an average person walks about 10,000 steps a day, a callus may cause 18,600 kg of <span class="hlt">excess</span> plantar <span class="hlt">pressure</span> per day. In addition, this study has proven the importance of early and regular removal of hyperkeratotic tissue. Even more aggressive removal could be recommended in patients with neuropathy and peripheral vascular disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S44C..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S44C..05K"><span>Using regional <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> response following the 3 Sep 2016 M­­w5.8 Pawnee, Oklahoma earthquake to constrain far-field seismicity rate forecasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kroll, K.; Murray, K. E.; Cochran, E. S.</p> <p>2016-12-01</p> <p>The 3 Sep 2016 M­­w5.8 Pawnee, Oklahoma earthquake was the largest event to occur in recorded history of the state. Widespread shaking from the event was felt in seven central U.S. states and caused damage as far away as Oklahoma City ( 115 km SSW). The Pawnee earthquake occurred soon after the deployment of a subsurface <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> monitoring network in Aug 2016. Eight <span class="hlt">pressure</span> transducers were installed downhole in inactive saltwater disposal wells that were completed in the basal sedimentary zone (the Arbuckle Group). The transducers are located in Alfalfa, Grant, and Payne Counties at distances of 48 to 140 km from the Pawnee earthquake. We observed coseismic fluid <span class="hlt">pressure</span> changes in all monitoring wells, indicating a large-scale poroelastic response in the Arbuckle. Two wells in Payne County lie in a zone of volumetric compression 48-52 km SSE of the rupture and experienced a co-seismic rise in fluid <span class="hlt">pressures</span> that we conclude was related to poroelastic rebound of the Arbuckle reservoir. We compare measurements of the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> change to estimated values given by the product of the volumetric strain, a Skempton's coefficient of 0.33, and a Bulk modulus of 25 GPa for fractured granitic basement rocks. We explore the possibility that the small increase in <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> may increase the rate of seismicity in regions outside of the mainshock region. We test this hypothesis by supplementing the Oklahoma Geological Survey earthquake catalog by semi-automated detection smaller magnitude (<2.6 M) earthquakes on seismic stations that are located in the vicinity of the wells. Using the events that occur in the week before the mainshock (27 Aug to 3 Sep 2016) as the background seismicity rate and the estimated <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> increase, we use a rate-state model to predict the seismicity rate change in the week following the event. We then compare the model predictions to the observed seismicity in the week following the Pawnee earthquake</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JChPh.142l4705M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JChPh.142l4705M"><span>Electrolyte <span class="hlt">pore</span>/solution partitioning by expanded grand canonical ensemble Monte Carlo simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moucka, Filip; Bratko, Dusan; Luzar, Alenka</p> <p>2015-03-01</p> <p>Using a newly developed grand canonical Monte Carlo approach based on fractional exchanges of dissolved ions and water molecules, we studied equilibrium partitioning of both components between laterally extended apolar confinements and surrounding electrolyte solution. Accurate calculations of the Hamiltonian and tensorial <span class="hlt">pressure</span> components at anisotropic conditions in the <span class="hlt">pore</span> required the development of a novel algorithm for a self-consistent correction of nonelectrostatic cut-off effects. At <span class="hlt">pore</span> widths above the kinetic threshold to capillary evaporation, the molality of the salt inside the confinement grows in parallel with that of the bulk phase, but presents a nonuniform width-dependence, being depleted at some and elevated at other separations. The presence of the salt enhances the layered structure in the slit and lengthens the range of inter-wall <span class="hlt">pressure</span> exerted by the metastable liquid. Solvation <span class="hlt">pressure</span> becomes increasingly repulsive with growing salt molality in the surrounding bath. Depending on the sign of the <span class="hlt">excess</span> molality in the <span class="hlt">pore</span>, the wetting free energy of <span class="hlt">pore</span> walls is either increased or decreased by the presence of the salt. Because of simultaneous rise in the solution surface tension, which increases the free-energy cost of vapor nucleation, the rise in the apparent hydrophobicity of the walls has not been shown to enhance the volatility of the metastable liquid in the <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22415579','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22415579"><span>Electrolyte <span class="hlt">pore</span>/solution partitioning by expanded grand canonical ensemble Monte Carlo simulation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moucka, Filip; Bratko, Dusan Luzar, Alenka</p> <p>2015-03-28</p> <p>Using a newly developed grand canonical Monte Carlo approach based on fractional exchanges of dissolved ions and water molecules, we studied equilibrium partitioning of both components between laterally extended apolar confinements and surrounding electrolyte solution. Accurate calculations of the Hamiltonian and tensorial <span class="hlt">pressure</span> components at anisotropic conditions in the <span class="hlt">pore</span> required the development of a novel algorithm for a self-consistent correction of nonelectrostatic cut-off effects. At <span class="hlt">pore</span> widths above the kinetic threshold to capillary evaporation, the molality of the salt inside the confinement grows in parallel with that of the bulk phase, but presents a nonuniform width-dependence, being depleted at some and elevated at other separations. The presence of the salt enhances the layered structure in the slit and lengthens the range of inter-wall <span class="hlt">pressure</span> exerted by the metastable liquid. Solvation <span class="hlt">pressure</span> becomes increasingly repulsive with growing salt molality in the surrounding bath. Depending on the sign of the <span class="hlt">excess</span> molality in the <span class="hlt">pore</span>, the wetting free energy of <span class="hlt">pore</span> walls is either increased or decreased by the presence of the salt. Because of simultaneous rise in the solution surface tension, which increases the free-energy cost of vapor nucleation, the rise in the apparent hydrophobicity of the walls has not been shown to enhance the volatility of the metastable liquid in the <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SolE....7..727P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SolE....7..727P"><span>Development of a numerical workflow based on μ-CT imaging for the determination of capillary <span class="hlt">pressure</span>-saturation-specific interfacial area relationship in 2-phase flow <span class="hlt">pore</span>-scale porous-media systems: a case study on Heletz sandstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peche, Aaron; Halisch, Matthias; Bogdan Tatomir, Alexandru; Sauter, Martin</p> <p>2016-05-01</p> <p>In this case study, we present the implementation of a finite element method (FEM)-based numerical <span class="hlt">pore</span>-scale model that is able to track and quantify the propagating fluid-fluid interfacial area on highly complex micro-computed tomography (μ-CT)-obtained geometries. Special focus is drawn to the relationship between reservoir-specific capillary <span class="hlt">pressure</span> (pc), wetting phase saturation (Sw) and interfacial area (awn). The basis of this approach is high-resolution μ-CT images representing the geometrical characteristics of a georeservoir sample. The successfully validated 2-phase flow model is based on the Navier-Stokes equations, including the surface tension force, in order to consider capillary effects for the computation of flow and the phase-field method for the emulation of a sharp fluid-fluid interface. In combination with specialized software packages, a complex high-resolution modelling domain can be obtained. A numerical workflow based on representative elementary volume (REV)-scale <span class="hlt">pore</span>-size distributions is introduced. This workflow aims at the successive modification of model and model set-up for simulating, such as a type of 2-phase problem on asymmetric μ-CT-based model domains. The geometrical complexity is gradually increased, starting from idealized <span class="hlt">pore</span> geometries until complex μ-CT-based <span class="hlt">pore</span> network domains, whereas all domains represent geostatistics of the REV-scale core sample <span class="hlt">pore</span>-size distribution. Finally, the model can be applied to a complex μ-CT-based model domain and the pc-Sw-awn relationship can be computed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRB..116.7303V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRB..116.7303V"><span>Upper crustal structure, seismicity and <span class="hlt">pore</span> <span class="hlt">pressure</span> variations in an extensional seismic belt through 3-D and 4-D VP and VP/VS models: The example of the Val d'Agri area (southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valoroso, L.; Improta, L.; de Gori, P.; Chiarabba, C.</p> <p>2011-07-01</p> <p>We use local earthquake tomography and background seismicity to investigate static and transient features of the crustal velocity structure in the Val d'Agri (southern Apennines, Italy), one of the regions in central Mediterranean with the highest seismogenic potential. The upper crust is dominated by two broad high-velocity anticlines of the buried Apulia Carbonate Platform ramping on two parallel high-angle thrusts interpreted as preexisting inverted normal faults. The deep core of the anticlines consists of very high VP (up to 6.9 km/s) and low VP/VS rocks, suggesting the involvement of the Apulian crystalline basement in the Apennine belt. These results provide valuable constraints on the Apennine belt tectonic evolution, supporting a thick-skinned interpretation for the Pliocene terminal phase of the compressional tectonics. The geometry of the Val d'Agri Quaternary basin is controlled by these inherited compressive features, whereas the presently active extensional tectonics barely reworked the structure. We find inconsistency between the structure of the Apulia Carbonate Platform and the location and geometry of the Quaternary normal faults mapped at the surface. This suggests either the immaturity of the normal faults or their secondary role in accommodating the extension. We observe spatiotemporal (4-D) changes of VP and VP/VS models defining transient variations of <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> in the upper crust. A strong change in the VP/VS ratio heralds a raise in the seismicity rate that can be related to large water level changes in a nearby artificial lake. This evidence is consistent with a mechanism of reservoir-induced seismicity by fluid <span class="hlt">pressure</span> increase and <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion. The 4-D velocity variations are confined in the shallow portion of the upper crust (3-6 km depth) where fluids are stored in a highly fractured medium. <span class="hlt">Pore</span> <span class="hlt">pressure</span> fluctuations can affect the strength of fault segments, favoring seismicity rate changes along the active</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAESc.117..107H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAESc.117..107H"><span>Sublithostatic <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> in the brittle-ductile transition zone of Mesozoic Yingxiu-Beichuan fault and its implication for the 2008 Mw 7.9 Wenchuan earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Han, Liang; Zhou, Yongsheng; He, Changrong; Li, Haibing</p> <p>2016-03-01</p> <p>In order to understand the mechanism for occurrence of large earthquakes in the Longmen Shan region, we indirectly estimated the flow stress and <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> in the brittle-ductile transition zone by studying exhumed granitic rocks which experienced Mesozoic ductile deformation, and constructed rheological profiles for the brittle regime and transition zone. The samples were collected from a small pluton that includes granites and deformed granitic rocks overthrust at an outcrop along the southern segment of the Yingxiu-Beichuan fault. The outcrop profile consists of granitic gneiss, protomylonite and mylonite. We observed that heterogeneous ductile deformation occurred in the brittle-ductile transition zone, and that the flow stress ranges from 15 to 80 MPa. Moreover, the fault in that zone experienced a temporary brittle deformation, which might indicate a high strain rate during the co-seismic process and early post-seismic creep. Secondary fluid inclusions were found and measured to define the possible range of the capture temperature and fluid <span class="hlt">pressure</span>. Sublithostatic <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> was determined at the capture temperatures of 330-350 °C during the process of filling and/or healing of microcracks. According to constructed rheological profiles and related mechanisms, high, sublithostatic <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> is likely to significantly weaken the fault and to be related to inception of a brittle fault slip above the brittle-ductile transition zone. A high strain rate driven by the coseismic slip in the brittle regime may lead to a brittle fault slip in the brittle-ductile transition zone, and then plastic deformation in the transition zone may resume gradually during post-seismic creep. The focal depth of the 2008 Mw 7.9 Wenchuan earthquake may be controlled by a velocity weakening to velocity strengthening transition in frictional slip (brittle regime) of granite around a temperature of 350 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16082450','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16082450"><span>[<span class="hlt">Excessive</span> daytime sleepiness].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bittencourt, Lia Rita Azeredo; Silva, Rogério Santos; Santos, Ruth Ferreira; Pires, Maria Laura Nogueira; Mello, Marco Túlio de</p> <p>2005-05-01</p> <p>Sleepiness is a physiological function, and can be defined as increased propension to fall asleep. However, <span class="hlt">excessive</span> sleepiness (ES) or hypersomnia refer to an abnormal increase in the probability to fall asleep, to take involuntary naps, or to have sleep atacks, when sleep is not desired. The main causes of <span class="hlt">excessive</span> sleepiness is chronic sleep deprivation, sleep apnea syndrome, narcolepsy, movement disorders during sleep, circadian sleep disorders, use of drugs and medications, or idiopathic hypersomnia. Social, familial, work, and cognitive impairment are among the consequences of hypersomnia. Moreover, it has also been reported increased risk of accidents. The treatment of <span class="hlt">excessive</span> sleepiness includes treating the primary cause, whenever identified. Sleep hygiene for sleep deprivation, positive <span class="hlt">pressure</span> (CPAP) for sleep apnea, dopaminergic agents and exercises for sleep-related movement disorders, phototherapy and/or melatonin for circadian disorders, and use of stimulants are the treatment modalities of first choice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017WRR....53.1891K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017WRR....53.1891K"><span><span class="hlt">Pore</span>-scale modeling of wettability alteration during primary drainage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kallel, W.; van Dijke, M. I. J.; Sorbie, K. S.; Wood, R.</p> <p>2017-03-01</p> <p>While carbonate reservoirs are recognized to be weakly-to-moderately oil-wet at the core-scale, <span class="hlt">pore</span>-scale wettability distributions remain poorly understood. In particular, the wetting state of micropores (<span class="hlt">pores</span> <5 µm in radius) is crucial for assessing multiphase flow processes, as microporosity can determine overall <span class="hlt">pore</span>-space connectivity. While oil-wet micropores are plausible, it is unclear how this may have occurred without invoking <span class="hlt">excessively</span> high capillary <span class="hlt">pressures</span>. Here we develop a novel mechanistic wettability alteration scenario that evolves during primary drainage, involving the release of small polar non-hydrocarbon compounds from the oil-phase into the water-phase. We implement a diffusion/adsorption model for these compounds that triggers a wettability alteration from initially water-wet to intermediate-wet conditions. This mechanism is incorporated in a quasi-static <span class="hlt">pore</span>-network model to which we add a notional time-dependency of the quasi-static invasion percolation mechanism. The model qualitatively reproduces experimental observations where an early rapid wettability alteration involving these small polar species occurred during primary drainage. Interestingly, we could invoke clear differences in the primary drainage patterns by varying both the extent of wettability alteration and the balance between the processes of oil invasion and wetting change. Combined, these parameters dictate the initial water saturation for waterflooding. Indeed, under conditions where oil invasion is slow compared to a fast and relatively strong wetting change, the model results in significant non-zero water saturations. However, for relatively fast oil invasion or small wetting changes, the model allows higher oil saturations at fixed maximum capillary <span class="hlt">pressures</span>, and invasion of micropores at moderate capillary <span class="hlt">pressures</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28808791','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28808791"><span>Consumption of extra virgin olive oil improves body composition and blood <span class="hlt">pressure</span> in women with <span class="hlt">excess</span> body fat: a randomized, double-blinded, placebo-controlled clinical trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Galvão Cândido, Flávia; Xavier Valente, Flávia; da Silva, Laís Emilia; Gonçalves Leão Coelho, Olívia; Gouveia Peluzio, Maria do Carmo; Gonçalves Alfenas, Rita de Cássia</p> <p>2017-08-14</p> <p>Despite the fact that extra virgin olive oil (EVOO) is widely used in obese individuals to treat cardiovascular diseases, the role of EVOO on weight/fat reduction remains unclear. We investigated the effects of energy-restricted diet containing EVOO on body composition and metabolic disruptions related to obesity. This is a randomized, double-blinded, placebo-controlled clinical trial in which 41 adult women with <span class="hlt">excess</span> body fat (mean ± SD 27.0 ± 0.9 year old, 46.8 ± 0.6% of total body fat) received daily high-fat breakfasts containing 25 mL of soybean oil (control group, n = 20) or EVOO (EVOO group, n = 21) during nine consecutive weeks. Breakfasts were part of an energy-restricted normal-fat diets (-2090 kJ, ~32%E from fat). Anthropometric and dual-energy X-ray absorptiometry were assessed, and fasting blood was collected on the first and last day of the experiment. Fat loss was ~80% higher on EVOO compared to the control group (mean ± SE: -2.4 ± 0.3 kg vs. -1.3 ± 0.4 kg, P = 0.037). EVOO also reduced diastolic blood <span class="hlt">pressure</span> when compared to control (-5.1 ± 1.6 mmHg vs. +0.3 ± 1.2 mmHg, P = 0.011). Within-group differences (P < 0.050) were observed for HDL-c (-2.9 ± 1.2 mmol/L) and IL-10 (+0.9 ± 0.1 pg/mL) in control group, and for serum creatinine (+0.04 ± 0.01 µmol/L) and alkaline phosphatase (-3.3 ± 1.8 IU/L) in the EVOO group. There was also a trend for IL-1β EVOO reduction (-0.3 ± 0.1 pg/mL, P = 0.060). EVOO consumption reduced body fat and improved blood <span class="hlt">pressure</span>. Our results indicate that EVOO should be included into energy-restricted programs for obesity treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6162107','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6162107"><span>Resolving <span class="hlt">pore</span>-space characteristics by rate-controlled porosimetry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yuan, H.H.; Swanson, B.F.</p> <p>1989-03-01</p> <p>By monitoring the mercury capillary <span class="hlt">pressure</span> in rate-controlled porosimetry (intrusion) experiments, new information regarding the <span class="hlt">pore</span> space of a rock sample has been obtained. With this technique, called an apparatus for <span class="hlt">pore</span> examination (APEX), it is now possible to resolve the <span class="hlt">pore</span> space of a rock sample into two interconnected parts. One part identifies the individual <span class="hlt">pore</span> systems (<span class="hlt">pore</span> bodies), which are low-energy sumps or regions of low capillarity. The other part corresponds to the <span class="hlt">pore</span> throats that interconnect with <span class="hlt">pore</span> systems. New capillary-<span class="hlt">pressure</span> curves have been obtained by partitioning the total capillary-<span class="hlt">pressure</span> curve (normal capillary-<span class="hlt">pressure</span> curve) into two subcurves: the subison capillary-<span class="hlt">pressure</span> curve, which details the distribution of <span class="hlt">pore</span> bodies, and the rison capillary-<span class="hlt">pressure</span> curve, which details the distribution of <span class="hlt">pore</span> throats. The authors present APEX data on Berea sandstone and San Andres dolomite that show the volume distribution of low-capillarity regions within the <span class="hlt">pore</span> space of these rocks. These regions of low capillarity are the principal <span class="hlt">pore</span>-space regions that trap the residual nonwetting phase upon imbibition of a strongly wetting fluid, as measured by toluene/air systems. The residual nonwetting-phase saturations as determined by the APEX method and by the toluene/air method are in excellent agreement. Thus, the detailed volume distribution of <span class="hlt">pore</span> systems responsible for trapped nonwetting-phase saturation is determined from APEX measurements, which can have important implications for EOR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19358591','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19358591"><span>Modeling of N2 adsorption in MCM-41 materials: hexagonal <span class="hlt">pores</span> versus cylindrical <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ustinov, Eugene A</p> <p>2009-07-07</p> <p>Low-temperature nitrogen adsorption in hexagonal <span class="hlt">pores</span> and equivalent cylindrical <span class="hlt">pores</span> is analyzed using nonlocal density functional theory extended to amorphous solids (NLDFT-AS). It is found that, despite significant difference of the density distribution over the cross-section of the <span class="hlt">pore</span>, the capillary condensation/evaporation <span class="hlt">pressure</span> is not considerably affected by the <span class="hlt">pore</span> shape being slightly lower in the case of hexagonal geometry. However, the condensation/evaporation step in the hexagonal <span class="hlt">pore</span> is slightly larger than that in the equivalent cylindrical <span class="hlt">pore</span> because in the latter case the <span class="hlt">pore</span> wall surface area and, hence, the amount adsorbed at <span class="hlt">pressures</span> below the evaporation <span class="hlt">pressure</span> are underestimated by 5%. We show that a dimensionless parameter defined as the ratio of the condensation/evaporation step and the upper value of the amount adsorbed at the condensation/evaporation <span class="hlt">pressure</span> can be used as an additional criterion of the correct choice of the gas-solid molecular parameters along with the dependence of condensation/evaporation <span class="hlt">pressure</span> on the <span class="hlt">pore</span> diameter. Application of the criteria to experimental data on nitrogen adsorption on a series of MCM-41 silica at 77 K corroborates some evidence that the capillary condensation occurs at equilibrium conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26736438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26736438"><span>Design of mechanical interface to re-distribute <span class="hlt">excess</span> <span class="hlt">pressure</span> to prevent the formation of decubitus ulcers in bed ridden patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nageswaran, Sharmila; Vijayakumar, Rekha; Sivarasu, Sudesh</p> <p>2015-08-01</p> <p><span class="hlt">Pressure</span> ulcers are the major problem in the stroke management and rehabilitation. Prevention of <span class="hlt">pressure</span> ulcer is of keen interest and is achieved by frequently changing the position of patient on the mattress. However, the care needs to be intensive to address this issue; else it would lead to <span class="hlt">pressure</span> ulcer or bed sores formation. Skin surface over the bony prominences provide comparatively more <span class="hlt">pressure</span> than the other regions. Therefore they are called as <span class="hlt">pressure</span> vulnerable regions. Skin over these regions is more susceptible for formation of ulcers. An engineering approach is needed to shift the accumulating <span class="hlt">pressure</span> from the <span class="hlt">pressure</span> vulnerable regions. Although <span class="hlt">pressure</span> sensed in these region would be more than that of which sensed in other regions, shifting protocol has to be designed to channelize or to grade the <span class="hlt">pressure</span> shift in order to avoid any injuries to the non <span class="hlt">pressure</span> vulnerable region. This paper aims at devising one such protocol using MATLab and thereby designing the layout of mattress using Pro/Engineer: the number of partitions needed to cover the entire surface of the skin that is in contact with the mattress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JChPh.119.2301M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JChPh.119.2301M"><span>Adsorption hysteresis in ink-bottle <span class="hlt">pore</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morishige, Kunimitsu; Tateishi, Noriko</p> <p>2003-07-01</p> <p>To examine the mechanism of the adsorption hysteresis in ink-bottle <span class="hlt">pores</span>, we measured the temperature dependence of the adsorption-desorption isotherms of argon, oxygen, and carbon dioxide onto SBA-16 ordered mesoporous material with cagelike <span class="hlt">pores</span>. The hysteresis loop always shrank with increasing temperature and eventually disappeared at a hysteresis temperature (Th), well below the bulk critical temperature (Tc). When the relative <span class="hlt">pressures</span> p/p0 of the capillary condensation and evaporation are plotted as a function of reduced temperature T/Tc, all the data including the transition <span class="hlt">pressures</span> for nitrogen reported previously are represented by a common curve. We also calculated the temperature dependence of the capillary condensation and evaporation <span class="hlt">pressures</span> of nitrogen under the assumption that adsorption and desorption in an ink-bottle <span class="hlt">pore</span> may be regarded as the process of the disappearance and formation of a gas bubble in a liquid droplet confined to the <span class="hlt">pore</span>. A fit between the observed and calculated transition <span class="hlt">pressures</span> in a wide temperature range was reasonable in light of several assumptions and approximations used. This clearly indicates that the energy barrier for the formation and disappearance of vapor bubbles in the liquid confined to the <span class="hlt">pores</span> is responsible for the appearance of the adsorption hysteresis and the hysteresis temperature is not concerned with the so-called capillary criticality. At temperatures higher than Th, the reversible capillary condensation takes place, because the energy barrier between a full liquid <span class="hlt">pore</span> and the vapor coexisting with the liquid film becomes surmountable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...120n2120V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...120n2120V"><span>Magnetocaloric effect and the influence of <span class="hlt">pressure</span> on magnetic properties of La-<span class="hlt">excess</span> pseudo-binary alloys La1+δ(Fe0.85Si0.15)13</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vuong, Van Hiep; Do Thi, Kim Anh; Thuan Nguyen, Khac; Le, Van Hong; Nhat Hoang, Nam</p> <p>2016-10-01</p> <p>The La-<span class="hlt">excess</span> alloys La1+δ(Fe0.85Si0.15)13 (δ = 0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature TC. The maximum entropy change -ΔSm was shown to be from 4.5 to 11.5 J/kg K for the applied field variation ΔH from 20 to 70 kOe, respectively. The estimated relative cooling power for ΔH = 70 kOe was 418 J/kg. The alloys show a typical NaZn13-type cubic structure, featuring a doping-induced magnetovolume effect with the increase in TC. Under the applied <span class="hlt">pressure</span> up to 2 GPa, the TC as deduced from resistance measurements decreased linearly, ΔTC = 113 (for δ = 0.06) and 111 K (for δ = 0.09), together with a corresponding decrease of resistivity, Δρ = 6.1 μΩ m at room temperature for both samples. At a low <span class="hlt">pressure</span>, the effect of spontaneous magnetostriction on TC caused by applying the <span class="hlt">pressure</span> appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-<span class="hlt">excess</span> doping. In comparison with other stoichiometric La(Fe1-xSix)13 compounds, the <span class="hlt">pressure</span> in our case was shown to have a smaller influence on TC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22080722','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22080722"><span><span class="hlt">Pressure</span>-induced phase transition(s) in KMnF3 and the importance of the <span class="hlt">excess</span> volume for phase transitions in perovskite structures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guennou, Mael; Bouvier, Pierre; Garbarino, Gaston; Kreisel, Jens; Salje, Ekhard K H</p> <p>2011-12-07</p> <p>We report a <span class="hlt">pressure</span>-dependent investigation of KMnF(3) by x-ray diffraction up to 30 GPa. The results are discussed in the framework of Landau theory and in relation to the isostructural phase transition in SrTiO(3). The phase transition temperature near 186 K in KMnF(3) shifts to room temperature at a critical <span class="hlt">pressure</span> of P(c) = 3.4 GPa; the <span class="hlt">pressure</span> dependence of the transition point follows ΔP(c)/ΔT(c) = 0.0315 GPa K(-1). The transition becomes second order under high <span class="hlt">pressure</span>, close to the tricritical point. The phase transition is determined by the rotation of MnF(6) octahedra with their simultaneous expansion along the rotation axis. The rotation angle was found to increase to 10.5° at 24 GPa. An additional anomaly was observed at higher <span class="hlt">pressure</span> around 25 GPa, suggesting a further phase transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JPCM...23V5901G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JPCM...23V5901G"><span><span class="hlt">Pressure</span>-induced phase transition(s) in KMnF3 and the importance of the <span class="hlt">excess</span> volume for phase transitions in perovskite structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guennou, Mael; Bouvier, Pierre; Garbarino, Gaston; Kreisel, Jens; Salje, Ekhard K. H.</p> <p>2011-12-01</p> <p>We report a <span class="hlt">pressure</span>-dependent investigation of KMnF3 by x-ray diffraction up to 30 GPa. The results are discussed in the framework of Landau theory and in relation to the isostructural phase transition in SrTiO3. The phase transition temperature near 186 K in KMnF3 shifts to room temperature at a critical <span class="hlt">pressure</span> of Pc = 3.4 GPa the <span class="hlt">pressure</span> dependence of the transition point follows ΔPc/ΔTc = 0.0315 GPa K-1. The transition becomes second order under high <span class="hlt">pressure</span>, close to the tricritical point. The phase transition is determined by the rotation of MnF6 octahedra with their simultaneous expansion along the rotation axis. The rotation angle was found to increase to 10.5° at 24 GPa. An additional anomaly was observed at higher <span class="hlt">pressure</span> around 25 GPa, suggesting a further phase transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H13P..01O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H13P..01O"><span><span class="hlt">Pore</span> Scale View of Fluid Displacement Fronts in Porous Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Or, D.; Moebius, F.</p> <p>2014-12-01</p> <p>The macroscopically smooth and regular motion of fluid fronts in porous media is composed of abrupt <span class="hlt">pore</span>-scale interfacial jumps involving intense interfacial energy release marked by <span class="hlt">pressure</span> bursts and acoustic emissions. The characteristics of these <span class="hlt">pore</span> scale events affect residual phase entrapment and the resulting unsaturated transport properties behind the front. Experimental studies using acoustic emissions technique (AE), rapid imaging, and <span class="hlt">pressure</span> measurements help characterize <span class="hlt">pore</span> scale processes during drainage and imbibition in model porous media. Imbibition and drainage produce different AE signatures (obeying a power law). For rapid drainage, AE signals persist long after cessation of front motion indicative of redistribution and interfacial relaxation. Rapid imaging revealed that interfacial jumps exceed mean front velocity and are highly inertial (Re>1000). Imaged <span class="hlt">pore</span> invasion volumes and <span class="hlt">pore</span> volumes deduced from waiting times between <span class="hlt">pressure</span> fluctuations were in remarkable agreement with geometric <span class="hlt">pores</span>. Differences between invaded volumes and geometrical <span class="hlt">pores</span> increase with increasing capillary numbers due to shorter <span class="hlt">pore</span> evacuation times and onset of simultaneous invasion events. A new mechanistic model for interfacial motions through a <span class="hlt">pore</span>-throat network enabled systematic evaluation of inertia in interfacial dynamics. Results suggest that in contrast to great sensitivity of <span class="hlt">pore</span> scale dynamics to variations in <span class="hlt">pore</span> geometry and boundary conditions, inertia exerts only a minor effect on average phase entrapment. <span class="hlt">Pore</span> scale invasion events paint a complex picture of rapid and inertial motions and provide new insights on mechanisms at displacement fronts essential for improving the macroscopic description of multiphase flow in porous media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.3552B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.3552B"><span>Evolution of <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> during folding and basin contraction in overpressured reservoirs assessed by combined fracture analysis and calcite twinning paleopiezometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beaudoin, Nicolas; Lacombe, Olivier; Bellahsen, Nicolas; Amrouch, Khalid; Daniel, Jean-Marc</p> <p>2014-05-01</p> <p>Reconstructing the evolution of paleofluid (over)<span class="hlt">pressure</span> in sedimentary basins during deformation is a challenging problem, especially when no hydrocarbon-bearing fluid inclusions are available to provide barometric constraints on the fluid system. This contribution reports the application to a natural case (the Bighorn Basin) of recent methodological advance to access fluid (over)<span class="hlt">pressure</span> level prevailing in strata during sub-seismic fracture development. The fluid <span class="hlt">pressure</span> evolution in the Mississippian-Permian Madison-Phosphoria carbonate reservoir is tentatively reconstructed from the early Sevier Layer Parallel Shortening to the Laramide folding in two basement-cored folds: the Sheep Mountain Anticline and the Rattlesnake Mountain Anticline, located on both edges of the Bighorn Basin. This reconstruction is based on a combination of stress inversion of fault slip data, calcite twins paleopiezometry and rock mechanics. Results point out that supra-hydrostatic <span class="hlt">pressure</span> values prevail in the carbonate reservoir during most of its whole Sevier-Laramide history, and a coeval evolution between fluid overpressure and differential stress build-up is also emphasized. In each fold, a maximum value of 30-35 MPa for overpressure (i.e. above hydrostatic value) is recorded, just before Laramide folding, while minimum values of 0 MPa or 7 MPa are recorded during Sevier foreland flexure/forebulge and Laramide folding, respectively. After normalization to the same depth for both folds of differential stress magnitudes obtained from calcite twins paleopiezometry, the reconstructed values for the two folds can be compared and this comparison provides an image of the evolution fluid <span class="hlt">pressure</span> levels at the basin scale. Until folding, the evolution of the fluid overpressure during deformation can be interpreted as reflecting large-scale fluid migrations in a laterally connected reservoir. The drop of fluid overpressure recorded in both folds during folding illustrates the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JESS..123.1729C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JESS..123.1729C"><span>An integral-free expression for short-term changes in fault stability due to <span class="hlt">pore</span> <span class="hlt">pressure</span> induced when a point load is placed on the pervious boundary of a porous elastic half space containing a fault</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chander, Ramesh; Tomar, S. K.</p> <p>2014-10-01</p> <p>A concentrated load with step-function time behaviour is placed normal to the planar, pervious boundary of a porous elastic half space (PEHS) with compressible constituents. A planar fault exists in the PEHS in such a way that the poroelastic behaviour of the medium is unhindered. We derive an approximate but integral-free expression for CFSCPP, i.e., changes in fault stability due to changes in <span class="hlt">pore</span> <span class="hlt">pressure</span>, at a point not too far off the line along which the load acts. But, in the interest of simplicity, the main discussion is focussed on a consideration of CFSCPP at a point P located on the fault at depth z directly beneath the load. It is convenient to introduce dimensionless time t D directly proportional to real time t. The constant of proportionality is 4 c/ z 2, where c is hydraulic diffusivity. The derived approximate expression gives results with an accuracy of greater than 99% for limited values of t D after the load is imposed. We learn from the derived expression that, for a given z, fault stability undergoes an initial sudden decrease commensurate with the undrained <span class="hlt">pore</span> <span class="hlt">pressure</span> induced in the PEHS. This is followed by a more gradual decrease in fault stability with increasing t D until a minimum is reached. The real time t to minimum fault stability increases with z. The magnitude of CFSCPP decreases with z as z -2 for a given t D in the permissible range. The derived expression and the inferences based on it should be useful during earth science investigations of the possible hazards due to reactivation of a pre-existing shallow fault when a civil engineering project involving imposition of a heavy load on the earth's surface is to be executed nearby. They should be useful also for investigations if a shallow earthquake occurs near such a project soon after its execution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028566','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028566"><span>Continuous borehole strain and <span class="hlt">pore</span> <span class="hlt">pressure</span> in the near field of the 28 September 2004 M 6.0 parkfield, California, earthquake: Implications for nucleation, fault response, earthquake prediction and tremor</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Johnston, M.J.S.; Borcherdt, R.D.; Linde, A.T.; Gladwin, M.T.</p> <p>2006-01-01</p> <p>Near-field observations of high-precision borehole strain and <span class="hlt">pore</span> <span class="hlt">pressure</span>, show no indication of coherent accelerating strain or <span class="hlt">pore</span> <span class="hlt">pressure</span> during the weeks to seconds before the 28 September 2004 M 6.0 Parkfield earthquake. Minor changes in strain rate did occur at a few sites during the last 24 hr before the earthquake but these changes are neither significant nor have the form expected for strain during slip coalescence initiating fault failure. Seconds before the event, strain is stable at the 10-11 level. Final prerupture nucleation slip in the hypocentral region is constrained to have a moment less than 2 ?? 1012 N m (M 2.2) and a source size less than 30 m. Ground displacement data indicate similar constraints. Localized rupture nucleation and runaway precludes useful prediction of damaging earthquakes. Coseismic dynamic strains of about 10 microstrain peak-to-peak were superimposed on volumetric strain offsets of about 0.5 microstrain to the northwest of the epicenter and about 0.2 microstrain to the southeast of the epicenter, consistent with right lateral slip. Observed strain and Global Positioning System (GPS) offsets can be simply fit with 20 cm of slip between 4 and 10 km on a 20-km segment of the fault north of Gold Hill (M0 = 7 ?? 1017 N m). Variable slip inversion models using GPS data and seismic data indicate similar moments. Observed postseismic strain is 60% to 300% of the coseismic strain, indicating incomplete release of accumulated strain. No measurable change in fault zone compliance preceding or following the earthquake is indicated by stable earth tidal response. No indications of strain change accompany nonvolcanic tremor events reported prior to and following the earthquake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21819070','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21819070"><span>Cavitation and <span class="hlt">pore</span> blocking in nanoporous glasses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reichenbach, C; Kalies, G; Enke, D; Klank, D</p> <p>2011-09-06</p> <p>In gas adsorption studies, porous glasses are frequently referred to as model materials for highly disordered mesopore systems. Numerous works suggest that an accurate interpretation of physisorption isotherms requires a complete understanding of network effects upon adsorption and desorption, respectively. The present article deals with nitrogen and argon adsorption at different temperatures (77 and 87 K) performed on a series of novel nanoporous glasses (NPG) with different mean <span class="hlt">pore</span> widths. NPG samples contain smaller mesopores and significantly higher microporosity than porous Vycor glass or controlled <span class="hlt">pore</span> glass. Since the mean <span class="hlt">pore</span> width of NPG can be tuned sensitively, the evolution of adsorption characteristics with respect to a broadening <span class="hlt">pore</span> network can be investigated starting from the narrowest nanopore width. With an increasing mean <span class="hlt">pore</span> width, a H2-type hysteresis develops gradually which finally transforms into a H1-type. In this connection, a transition from a cavitation-induced desorption toward desorption controlled by <span class="hlt">pore</span> blocking can be observed. Furthermore, we find concrete hints for a <span class="hlt">pore</span> size dependence of the relative <span class="hlt">pressure</span> of cavitation in highly disordered <span class="hlt">pore</span> systems. By comparing nitrogen and argon adsorption, a comprehensive insight into adsorption mechanisms in novel disordered materials is provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1264250','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1264250"><span>Demonstration of fuel hot-spot <span class="hlt">pressure</span> in <span class="hlt">excess</span> of 50 Gbar for direct-drive, layered deuterium-tritium implosions on OMEGA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; Sangster, T. C.; Betti, R.; Bose, A.; Boehly, T. R.; Bonino, M. J.; Campbell, E. M.; Cao, D.; Collins, T. J. B.; Craxton, R. S.; Davis, A. K.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu Johnson, M.; Glebov, V. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Jacobs-Perkins, D.; Janezic, R.; Karasik, M.; Keck, R. L.; Kelly, J. H.; Kessler, T. J.; Knauer, J. P.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Obenschain, S. P.; Petrasso, R. D.; Radha, P. B.; Rice, B.; Rosenberg, M. J.; Schmitt, A. J.; Schmitt, M. J.; Seka, W.; Shmayda, W. T.; Shoup, III, M. J.; Shvydky, A.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Theobald, W.; Ulreich, J.; Wittman, M. D.; Woo, K. M.; Yaakobi, B.; Zuegel, J. D.</p> <p>2016-07-07</p> <p>A record fuel hot-spot <span class="hlt">pressure</span> P<sub>hs</sub> = 56±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium–tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility (NIF), these implosions achieved a Lawson parameter ~60% of the value required for ignition [A. Bose et al., Phys. Rev. E (in press)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold <span class="hlt">pressure</span>. Relative to symmetric, one-dimensional simulations, the inferred hot-spot <span class="hlt">pressure</span> is ~40% lower. Furthermore, three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1264250','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1264250"><span>Demonstration of fuel hot-spot <span class="hlt">pressure</span> in <span class="hlt">excess</span> of 50 Gbar for direct-drive, layered deuterium-tritium implosions on OMEGA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; Sangster, T. C.; Betti, R.; Bose, A.; Boehly, T. R.; Bonino, M. J.; Campbell, E. M.; Cao, D.; Collins, T. J. B.; Craxton, R. S.; Davis, A. K.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu Johnson, M.; Glebov, V. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Jacobs-Perkins, D.; Janezic, R.; Karasik, M.; Keck, R. L.; Kelly, J. H.; Kessler, T. J.; Knauer, J. P.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Obenschain, S. P.; Petrasso, R. D.; Radha, P. B.; Rice, B.; Rosenberg, M. J.; Schmitt, A. J.; Schmitt, M. J.; Seka, W.; Shmayda, W. T.; Shoup, III, M. J.; Shvydky, A.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Theobald, W.; Ulreich, J.; Wittman, M. D.; Woo, K. M.; Yaakobi, B.; Zuegel, J. D.</p> <p>2016-07-07</p> <p>A record fuel hot-spot <span class="hlt">pressure</span> P<sub>hs</sub> = 56±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium–tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility (NIF), these implosions achieved a Lawson parameter ~60% of the value required for ignition [A. Bose et al., Phys. Rev. E (in press)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold <span class="hlt">pressure</span>. Relative to symmetric, one-dimensional simulations, the inferred hot-spot <span class="hlt">pressure</span> is ~40% lower. Furthermore, three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvL.117b5001R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvL.117b5001R"><span>Demonstration of Fuel Hot-Spot <span class="hlt">Pressure</span> in <span class="hlt">Excess</span> of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; Sangster, T. C.; Betti, R.; Bose, A.; Boehly, T. R.; Bonino, M. J.; Campbell, E. M.; Cao, D.; Collins, T. J. B.; Craxton, R. S.; Davis, A. K.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu Johnson, M.; Glebov, V. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Jacobs-Perkins, D.; Janezic, R.; Karasik, M.; Keck, R. L.; Kelly, J. H.; Kessler, T. J.; Knauer, J. P.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Obenschain, S. P.; Petrasso, R. D.; Radha, P. B.; Rice, B.; Rosenberg, M. J.; Schmitt, A. J.; Schmitt, M. J.; Seka, W.; Shmayda, W. T.; Shoup, M. J.; Shvydky, A.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Theobald, W.; Ulreich, J.; Wittman, M. D.; Woo, K. M.; Yaakobi, B.; Zuegel, J. D.</p> <p>2016-07-01</p> <p>A record fuel hot-spot <span class="hlt">pressure</span> Phs=56 ±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ˜60 % of the value required for ignition [A. Bose et al., Phys. Rev. E 93, LM15119ER (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold <span class="hlt">pressure</span>. Relative to symmetric, one-dimensional simulations, the inferred hot-spot <span class="hlt">pressure</span> is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1264250-demonstration-fuel-hot-spot-pressure-excess-gbar-direct-drive-layered-deuterium-tritium-implosions-omega','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1264250-demonstration-fuel-hot-spot-pressure-excess-gbar-direct-drive-layered-deuterium-tritium-implosions-omega"><span>Demonstration of fuel hot-spot <span class="hlt">pressure</span> in <span class="hlt">excess</span> of 50 Gbar for direct-drive, layered deuterium-tritium implosions on OMEGA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; ...</p> <p>2016-07-07</p> <p>A record fuel hot-spot <span class="hlt">pressure</span> Phs = 56±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium–tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility (NIF), these implosions achieved a Lawson parameter ~60% of the value required for ignition [A. Bose et al., Phys. Rev. E (in press)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold <span class="hlt">pressure</span>. Relative to symmetric, one-dimensional simulations, the inferred hot-spot <span class="hlt">pressure</span> is ~40%more » lower. Furthermore, three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25093351','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25093351"><span>Crystal chemistry of anion-<span class="hlt">excess</span> ReO3-related phases. III. γ-ZrF4, a high-<span class="hlt">pressure</span> form of zirconiumtetra fluoride, and a comparison of MX4 structure types.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laval, Jean Paul</p> <p>2014-08-01</p> <p>The crystal structure of the high-<span class="hlt">pressure</span> (4-8 GPa) form of zirconium tetrafluoride, γ-ZrF4, is based on the association by corner- and edge-sharing of ZrF8 triangulated dodecahedra, forming a three-dimensional framework. It presents some analogies with high-temperature α-ZrF4 but clearly constitutes a new MX4 structure type. The main MX4 ionic structure types, and especially those deriving from the `anion-<span class="hlt">excess</span> ReO3-type', are compared and it is shown that the TeF4 structure can also be included in this family.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17975755','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17975755"><span>Prevalence of <span class="hlt">excessive</span> body weight and high blood <span class="hlt">pressure</span> in children and adolescents in the city of Łódź.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ostrowska-Nawarycz, Lidia; Nawarycz, Tadeusz</p> <p>2007-09-01</p> <p>Overweight and elevated blood <span class="hlt">pressure</span> in children and adolescents are two independent risk factors of basic importance for early prevention of cardiovascular and metabolic diseases. To evaluate the prevalence of overweight and elevated blood <span class="hlt">pressure</span> in children and adolescents aged 7-18 years from the city of Łódź. A total of 25,309 children and adolescents (12,669 girls and 12,640 boys) aged 7-19 years from 111 schools in the city of Łódź were examined. Basic anthropometric measurements (body mass and height) as well as three independent blood <span class="hlt">pressure</span> measurements using the auscultatory method were performed. The prevalence of overweight and obesity were evaluated based on BMI analysis and using international criteria (IOTF). The prevalence of prehypertension state and hypertension was evaluated using the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood <span class="hlt">Pressure</span> in Children and Adolescents. The mean prevalence of overweight (without obesity) was 15.1% (13.2% for girls and 17% for boys) and obesity was found in 3.7% of children (2.9% of girls and 4.4% of boys). Prevalence of the prehypertensive state and hypertension was 11.1% and 4.9%, respectively. In the younger groups of children aged 7-13 years the prevalence of overweight as well as elevated blood <span class="hlt">pressure</span> was significantly (p <0.001) higher than in groups aged 14-19 years. The results indicate that the prevalence of overweight as well as elevated blood <span class="hlt">pressure</span> is significantly higher in younger groups of children. The observed relations may result from specific social determinants and improper nutritional habits. The results show that intensive preventive activities should also be directed towards younger groups of children.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22416227','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22416227"><span>Local <span class="hlt">pressure</span> components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit <span class="hlt">pore</span> obtained by the perturbative method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fujiwara, K.; Shibahara, M.</p> <p>2015-03-07</p> <p>A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit <span class="hlt">pore</span> in order to reveal local thermodynamic states: local <span class="hlt">pressure</span> components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the local thermodynamic quantities from a molecular point of view. An instantaneous expression of the local <span class="hlt">pressure</span> components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the local <span class="hlt">pressure</span> components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative method. The results revealed that the local <span class="hlt">pressure</span> components tangential to the solid surface in the vicinity of the 1st fluid layer from the solid surface are different in a two dimensional plane, and the difference became pronounced in the vicinity of the corner of the slit, for cases where the fluid-solid interaction intensities are relatively strong. The results for the local interfacial tensions of the fluid inside the slit suggested that the local interfacial tensions in the vicinity of the 2nd and 3rd layers of the solid atoms from the entrance of the slit act as a trigger for the transition between the two states under the influence of a varying fluid-solid interaction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=138961','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=138961"><span>The nuclear <span class="hlt">pore</span> complex</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Adam, Stephen A</p> <p>2001-01-01</p> <p>Nuclear <span class="hlt">pore</span> complexes, the conduits for information exchange between the nucleus and cytoplasm, appear broadly similar in eukaryotes from yeast to human. Precisely how nuclear <span class="hlt">pore</span> complexes regulate macromolecular and ionic traffic remains unknown, but recent advances in the identification and characterization of components of the complex by proteomics and genomics have provided new insights. PMID:11574060</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4067534','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4067534"><span><span class="hlt">EXCESS</span> <span class="hlt">PRESSURE</span> INTEGRAL PREDICTS CARDIOVASCULAR EVENTS INDEPENDENT OF OTHER RISK FACTORS IN THE CONDUIT ARTERY FUNCTIONAL EVALUATION (CAFE) SUB-STUDY OF ANGLO-SCANDINAVIAN CARDIAC OUTCOMES TRIAL (ASCOT)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Davies, Justin E; Lacy, Peter; Tillin, Therese; Collier, David; Cruickshank, J Kennedy; Francis, Darrel P; Malaweera, Anura; Mayet, Jamil; Stanton, Alice; Williams, Bryan; Parker, Kim H; McG Thom, Simon A; Hughes, Alun D</p> <p>2014-01-01</p> <p><span class="hlt">Excess</span> <span class="hlt">pressure</span> integral (XSPI), a new index of surplus work performed by the left ventricle, can be calculated from blood <span class="hlt">pressure</span> (BP) waveforms and may indicate circulatory dysfunction. We investigated whether XSPI predicted future cardiovascular (CV) events and target organ damage in treated hypertensive individuals. Radial BP waveforms were acquired by tonometry in 2069 individuals (63±8y) in the Conduit Artery Functional Evaluation sub-study of the Anglo-Scandinavian Cardiac Outcomes trial. Measurements of left ventricular mass index (LVMI; n = 862) and common carotid artery intima media thickness (cIMT; n = 923) were also performed. XSPI and the integral of reservoir <span class="hlt">pressure</span> (PRI) were lower in people treated with amlodipine ± perindopril than atenolol ± bendroflumethiazide, although brachial systolic BP was similar. A total of 134 CV events accrued over a median 3.4 years of follow-up; XSPI was a significant predictor of CV events after adjustment for age and sex and this relationship was unaffected by adjustment for conventional CV risk factors or Framingham risk score. XSPI, central systolic BP, central augmentation <span class="hlt">pressure</span> (AP), central pulse <span class="hlt">pressure</span> (cPP) and PRI were correlated with LVMI, but only XSPI, AP and cPP were positively associated with cIMT. Associations between LVMI and XSPI and PRI, and cIMT and XSPI were unaffected by multivariable adjustment for other covariates. XSPI is a novel indicator of CV dysfunction and independently predicts CV events and target organ damage in a prospective clinical trial. PMID:24821941</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28931873','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28931873"><span>Characterization of Methane <span class="hlt">Excess</span> and Absolute Adsorption in Various Clay Nanopores from Molecular Simulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tian, Yuanyuan; Yan, Changhui; Jin, Zhehui</p> <p>2017-09-20</p> <p>In this work, we use grand canonical Monte Carlo (GCMC) simulation to study methane adsorption in various clay nanopores and analyze different approaches to characterize the absolute adsorption. As an important constituent of shale, clay minerals can have significant amount of nanopores, which greatly contribute to the gas-in-place in shale. In previous works, absolute adsorption is often calculated from the <span class="hlt">excess</span> adsorption and bulk liquid phase density of absorbate. We find that methane adsorbed phase density keeps increasing with <span class="hlt">pressure</span> up to 80 MPa. Even with updated adsorbed phase density from GCMC, there is a significant error in absolute adsorption calculation. Thus, we propose to use the <span class="hlt">excess</span> adsorption and adsorbed phase volume to calculate absolute adsorption and reduce the discrepancy to less than 3% at high <span class="hlt">pressure</span> conditions. We also find that the supercritical Dubinin-Radushkevich (SDR) fitting method which is commonly used in experiments to convert the <span class="hlt">excess</span> adsorption to absolute adsorption may not have a solid physical foundation for methane adsorption. The methane <span class="hlt">excess</span> and absolute adsorptions per specific surface area are similar for different clay minerals in line with previous experimental data. In mesopores, the <span class="hlt">excess</span> and absolute adsorptions per specific surface area become insensitive to <span class="hlt">pore</span> size. Our work should provide important fundamental understandings and insights into accurate estimation of gas-in-place in shale reservoirs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22597609','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22597609"><span>Magnetocaloric effect and the influence of <span class="hlt">pressure</span> on magnetic properties of La-<span class="hlt">excess</span> pseudo-binary alloys La{sub 1+δ}(Fe{sub 0.85}Si{sub 0.15}){sub 13}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vuong, Van Hiep; Do Thi, Kim Anh; Thuan Nguyen, Khac; Nhat Hoang, Nam E-mail: nhathn@vnu.edu.vn; Le, Van Hong</p> <p>2016-10-14</p> <p>The La-<span class="hlt">excess</span> alloys La{sub 1+δ}(Fe{sub 0.85}Si{sub 0.15}){sub 13} (δ = 0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature T{sub C}. The maximum entropy change −ΔS{sub m} was shown to be from 4.5 to 11.5 J/kg K for the applied field variation ΔH from 20 to 70 kOe, respectively. The estimated relative cooling power for ΔH = 70 kOe was 418 J/kg. The alloys show a typical NaZn{sub 13}-type cubic structure, featuring a doping-induced magnetovolume effect with the increase in T{sub C}. Under the applied <span class="hlt">pressure</span> up to 2 GPa, the T{sub C} as deduced from resistance measurements decreased linearly, ΔT{sub C} = 113 (for δ = 0.06) and 111 K (for δ = 0.09), together with a corresponding decrease of resistivity, Δρ = 6.1 μΩ m at room temperature for both samples. At a low <span class="hlt">pressure</span>, the effect of spontaneous magnetostriction on T{sub C} caused by applying the <span class="hlt">pressure</span> appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-<span class="hlt">excess</span> doping. In comparison with other stoichiometric La(Fe{sub 1−x}Si{sub x}){sub 13} compounds, the <span class="hlt">pressure</span> in our case was shown to have a smaller influence on T{sub C}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27447511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27447511"><span>Demonstration of Fuel Hot-Spot <span class="hlt">Pressure</span> in <span class="hlt">Excess</span> of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Regan, S P; Goncharov, V N; Igumenshchev, I V; Sangster, T C; Betti, R; Bose, A; Boehly, T R; Bonino, M J; Campbell, E M; Cao, D; Collins, T J B; Craxton, R S; Davis, A K; Delettrez, J A; Edgell, D H; Epstein, R; Forrest, C J; Frenje, J A; Froula, D H; Gatu Johnson, M; Glebov, V Yu; Harding, D R; Hohenberger, M; Hu, S X; Jacobs-Perkins, D; Janezic, R; Karasik, M; Keck, R L; Kelly, J H; Kessler, T J; Knauer, J P; Kosc, T Z; Loucks, S J; Marozas, J A; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Myatt, J F; Obenschain, S P; Petrasso, R D; Radha, P B; Rice, B; Rosenberg, M J; Schmitt, A J; Schmitt, M J; Seka, W; Shmayda, W T; Shoup, M J; Shvydky, A; Skupsky, S; Solodov, A A; Stoeckl, C; Theobald, W; Ulreich, J; Wittman, M D; Woo, K M; Yaakobi, B; Zuegel, J D</p> <p>2016-07-08</p> <p>A record fuel hot-spot <span class="hlt">pressure</span> P_{hs}=56±7  Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, 011201(R) (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold <span class="hlt">pressure</span>. Relative to symmetric, one-dimensional simulations, the inferred hot-spot <span class="hlt">pressure</span> is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GGG.....9.3019K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GGG.....9.3019K"><span>Gas hydrate dissociation in sediments: <span class="hlt">Pressure</span>-temperature evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwon, Tae-Hyuk; Cho, Gye-Chun; Santamarina, J. Carlos</p> <p>2008-03-01</p> <p>Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations or intentionally as part of gas extraction from the hydrate itself. In all cases, high <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> generation is anticipated during hydrate dissociation. A comprehensive formulation is derived for the prediction of fluid <span class="hlt">pressure</span> evolution in hydrate-bearing sediments subjected to thermal stimulation without mass transfer. The formulation considers <span class="hlt">pressure</span>- and temperature-dependent volume changes in all phases, effective stress-controlled sediment compressibility, capillarity, and the relative solubilities of fluids. Salient implications are explored through parametric studies. The model properly reproduces experimental data, including the PT evolution along the phase boundary during dissociation and the effect of capillarity. <span class="hlt">Pore</span> fluid <span class="hlt">pressure</span> generation is proportional to the initial hydrate fraction and the sediment bulk stiffness; is inversely proportional to the initial gas fraction and gas solubility; and is limited by changes in effective stress that cause the failure of the sediment. When the sediment stiffness is high, the generated <span class="hlt">pore</span> <span class="hlt">pressure</span> reflects thermal and <span class="hlt">pressure</span> changes in water, hydrate, and mineral densities. Comparative analyses for CO2 and CH4 highlight the role of gas solubility in <span class="hlt">excess</span> <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> generation. Dissociation in small <span class="hlt">pores</span> experiences melting point depression due to changes in water activity, and lower <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> generation due to the higher gas <span class="hlt">pressure</span> in small gas bubbles. Capillarity effects may be disregarded in silts and sands, when hydrates are present in nodules and lenses and when the sediment experiences hydraulic fracture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20883049','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20883049"><span>Reaction of a phospholipid monolayer with gas-phase ozone at the air-water interface: measurement of surface <span class="hlt">excess</span> and surface <span class="hlt">pressure</span> in real time.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thompson, Katherine C; Rennie, Adrian R; King, Martin D; Hardman, Samantha J O; Lucas, Claire O M; Pfrang, Christian; Hughes, Brian R; Hughes, Arwel V</p> <p>2010-11-16</p> <p>The reaction between gas-phase ozone and monolayers of the unsaturated lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC, on aqueous solutions has been studied in real time using neutron reflection and surface <span class="hlt">pressure</span> measurements. The reaction between ozone and lung surfactant, which contains POPC, leads to decreased pulmonary function, but little is known about the changes that occur to the interfacial material as a result of oxidation. The results reveal that the initial reaction of ozone with POPC leads to a rapid increase in surface <span class="hlt">pressure</span> followed by a slow decrease to very low values. The neutron reflection measurements, performed on an isotopologue of POPC with a selectively deuterated palmitoyl strand, reveal that the reaction leads to loss of this strand from the air-water interface, suggesting either solubilization of the product lipid or degradation of the palmitoyl strand by a reactive species. Reactions of (1)H-POPC on D(2)O reveal that the headgroup region of the lipids in aqueous solution is not dramatically perturbed by the reaction of POPC monolayers with ozone supporting degradation of the palmitoyl strand rather than solubilization. The results are consistent with the reaction of ozone with the oleoyl strand of POPC at the air-water interface leading to the formation of OH radicals. The highly reactive OH radicals produced can then go on to react with the saturated palmitoyl strands leading to the formation of oxidized lipids with shorter alkyl tails.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996AAS...188.0203B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996AAS...188.0203B"><span>Velocities in Solar <span class="hlt">Pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.</p> <p>1996-05-01</p> <p>We investigate the three dimensional structure of solar <span class="hlt">pores</span> and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around <span class="hlt">pores</span> with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in <span class="hlt">pores</span> increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the <span class="hlt">pores</span> appear near these boundaries. We analyze the vertical velocity structure in <span class="hlt">pores</span> and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for <span class="hlt">pores</span>. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JChPh..83.1888M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JChPh..83.1888M"><span>Molecular dynamics of narrow, liquid-filled <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Magda, J. J.; Tirrell, M.; Davis, H. T.</p> <p>1985-08-01</p> <p>Molecular dynamics studies are reported for a 6-12 Lennard-Jones liquid in <span class="hlt">pore</span> channels ranging from about 2-12 molecules wide. The <span class="hlt">pore</span> walls are modeled as flat surfaces interacting with the fluid molecules via a continuous potential varying only with perpendicular distance from the wall. Liquid density profiles, solvation forces, interfacial tensions, and self-diffusion coefficients along the <span class="hlt">pore</span> axis were computed. The density profiles indicate multilayer adsorption in the <span class="hlt">pore</span>, whereas the locally defined diffusion coefficients do not vary significantly across the <span class="hlt">pore</span>. The <span class="hlt">pore</span>-averaged diffusivity as well as the solvation force oscillate with varying <span class="hlt">pore</span> width at constant chemical potential. For <span class="hlt">pore</span> widths greater than ten molecular diameters, the average diffusion coefficient is almost equal to its bulk value, and the solvation force equals the bulk <span class="hlt">pressure</span>. In the smaller <span class="hlt">pores</span> the mean square displacement normal to the <span class="hlt">pore</span> walls never achieves linearity in time, and thus does not reach a diffusive limit. Thermodynamic equations relating the solvation force to the interfacial tension are derived, and the appropriate mechanical expressions for these quantities are identified. Simulation results are shown to be consistent with these thermodynamic equations. The simulations presented here will be useful in the development of the theory of fluid structure and transport in the tight <span class="hlt">pores</span> occurring in such materials as vicor glass, clay dispersions, and biological <span class="hlt">pores</span> and membranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5380851','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5380851"><span><span class="hlt">Excess</span> of Aminopeptidase A in the Brain Elevates Blood <span class="hlt">Pressure</span> via the Angiotensin II Type 1 and Bradykinin B2 Receptors without Dipsogenic Effect</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ishida, Akio; Ohya, Yusuke</p> <p>2017-01-01</p> <p>Aminopeptidase A (APA) cleaves angiotensin (Ang) II, kallidin, and other related peptides. In the brain, it activates the renin angiotensin system and causes hypertension. Limited data are available on the dipsogenic effect of APA and pressor effect of degraded peptides of APA such as bradykinin. Wistar-Kyoto rats received intracerebroventricular (icv) APA in a conscious, unrestrained state after pretreatment with (i) vehicle, (ii) 80 μg of telmisartan, an Ang II type-1 (AT1) receptor blocker, (iii) 800 nmol of amastatin, an aminopeptidase inhibitor, and (iv) 1 nmol of HOE-140, a bradykinin B2 receptor blocker. Icv administration of 400 and 800 ng of APA increased blood <span class="hlt">pressure</span> by 12.6 ± 3.0 and 19.0 ± 3.1 mmHg, respectively. APA did not evoke drinking behavior. Pressor response to APA was attenuated on pretreatment with telmisartan (vehicle: 22.1 ± 2.2 mmHg versus telmisartan: 10.4 ± 3.2 mmHg). Pressor response to APA was also attenuated with amastatin and HOE-140 (vehicle: 26.5 ± 1.1 mmHg, amastatin: 14.4 ± 4.2 mmHg, HOE-140: 16.4 ± 2.2 mmHg). In conclusion, APA increase in the brain evokes a pressor response via enzymatic activity without dipsogenic effect. AT1 receptors and B2 receptors in the brain may contribute to the APA-induced pressor response. PMID:28421141</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10594','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10594"><span>Evaluation of the Long-Term Performance of Titanate Ceramics for Immobilization of <span class="hlt">Excess</span> Weapons Plutonium: Results from <span class="hlt">Pressurized</span> Unsaturated Flow and Single Pass Flow-Through Testing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>BP McGrail; HT Schaef; JP Icenhower; PF Martin; RD Orr; VL Legore</p> <p>1999-09-13</p> <p>This report summarizes our findings from <span class="hlt">pressurized</span> unsaturated flow (PUF) and single-pass flow-through (SPFT) experiments to date. Results from the PUF test of a Pu-bearing ceramic with enclosing surrogate high-level waste glass show that the glass reacts rapidly to alteration products. Glass reaction causes variations in the solution pH in contact with the ceramic materials. We also document variable concentrations of Pu in solution, primarily in colloidal form, which appear to be related to secular variations in solution composition. The apparent dissolution rate of the ceramic waste form, based on Ba concentrations in the effluent, is estimated at {le} 10{sup {minus}5} g/(m{sup 2} {center_dot} d). Pu-bearing colloids were recovered in the size range of 0.2 to 2 {micro}m, but it is not clear that such entities would be transported in a system that is not advective-flow dominated. Results from SPFT experiments give information on the corrosion resistance of two surrogate Pu-ceramics (Ce-pyrochlore and Ce-zirconolite) at 90 C over a pH range of 2 to 12. The two ceramics were doped with minor quantities ({approximately}0.1 mass%) of MoO{sub 3}, so that concentrations of Mo in the effluent solution could be used to monitor the reaction behavior of the materials. The data obtained thus far from experiments with durations up to 150 d do not conclusively prove that the solid-aqueous solution systems have reached steady-state conditions. Therefore, the dissolution mechanism cannot be determined. Apparent dissolution rates of the two ceramic materials based on Ce, Gd, and Mo concentrations in the effluent solutions from the SPFT are nearly identical and vary between 1.1 to 8.5 x 10{sup {minus}4} g/(m{sup 2} {center_dot} d). In addition, the data reveal a slightly amphoteric dissolution behavior, with a minimum apparent rate at pH = 7 to 8, over the pH range examined. Results from two related ceramic samples suggest that radiation damage can have a measurable effect on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989PhDT.......165W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989PhDT.......165W"><span>Capillary Properties of Model <span class="hlt">Pores</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walsh, Tim J.</p> <p></p> <p>Available from UMI in association with The British Library. Liquid menisci in small <span class="hlt">pores</span> exhibit a curved surface across which there is a significant <span class="hlt">pressure</span> difference. In the past it has been difficult to calculate the curvatures, of this class of menisci. Some recent studies have shown that a relatively straightforward, but hitherto neglected, method originated by Mayer & Stowe (1965) and Princen (1969a) can be applied to analyse wedging menisci. However, the method has lacked a comprehensive experimental verification. This investigation follows on from the previously limited studies. A standardised method for the application of the analysis is described, the results from which are compared to observations made using modified experimental procedures. The behaviour of the capillary surfaces formed in several model <span class="hlt">pores</span> are analysed with the method. The model systems studied are rectangular ducts, the <span class="hlt">pores</span> formed by a rod in an angled corner, by two contacting rods and a plate and the space between a rod and a plate. For the latter two shapes the analysis is extended to include systems of mixed wettability which have a particular bearing on enhanced oil recovery operations. Experiments in which curvatures are inferred from observations of capillary rise, are performed using two comparative techniques. An involved procedure confirms predictions of meniscus curvature to within 0.3%. Use of a more straightforward, through less accurate, technique enables variations of curvature with tube shape or contact angle(s) to be conveniently studied. Results obtained are excellent and confirm the theory within the determined experimental errors. (Abstract shortened by UMI.).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036504','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036504"><span><span class="hlt">Pore</span> networks in continental and marine mudstones: Characteristics and controls on sealing behavior</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Heath, J.E.; Dewers, T.A.; McPherson, B.J.O.L.; Petrusak, R.; Chidsey, T.C.; Rinehart, A.J.; Mozley, P.S.</p> <p>2011-01-01</p> <p>Mudstone <span class="hlt">pore</span> networks are strong modifiers of sedimentary basin fluid dynamics and have a critical role in the distribution of hydrocarbons and containment of injected fluids. Using core samples from continental and marine mudstones, we investigate properties of <span class="hlt">pore</span> types and networks from a variety of geologic environments, together with estimates of capillary beam- scanning electron microscopy, suggest seven dominant mudstone <span class="hlt">pore</span> types distinguished by geometry and connectivity. A dominant planar <span class="hlt">pore</span> type occurs in all investigated mudstones and generally has high coordination numbers (i.e., number of neighboring connected <span class="hlt">pores</span>). Connected networks of <span class="hlt">pores</span> of this type contribute to high mercury capillary <span class="hlt">pressures</span> due to small <span class="hlt">pore</span> throats at the junctions of connected <span class="hlt">pores</span> and likely control most matrix transport in these mudstones. Other <span class="hlt">pore</span> types are related to authigenic (e.g., replacement or <span class="hlt">pore</span>-lining precipitation) clay minerals and pyrite nodules; <span class="hlt">pores</span> in clay packets adjacent to larger, more competent clastic grains; <span class="hlt">pores</span> in organic phases; and stylolitic and microfracture-related <span class="hlt">pores</span>. <span class="hlt">Pores</span> within regions of authigenic clay minerals often form small isolated networks (<3 ??m). <span class="hlt">Pores</span> in stringers of organic phases occur as tubular <span class="hlt">pores</span> or slit- and/or sheet-like <span class="hlt">pores</span>. These form short, connected lengths in 3D reconstructions, but appear to form networks no larger than a few microns in size. Sealing efficiency of the studied mudstones increases with greater distal depositional environments and greater maximum depth of burial. ?? 2011 Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1342226-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1342226-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains"><span>Differences in soluble organic carbon chemistry in <span class="hlt">pore</span> waters sampled from different <span class="hlt">pore</span> size domains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Bailey, Vanessa L.; Smith, A. P.; Tfaily, Malak; ...</p> <p>2017-01-11</p> <p>Spatial isolation of soil organic carbon (SOC) in different sized <span class="hlt">pores</span> may be a mechanism by which otherwise labile carbon (C) could be protected in soils. When soil water content increases, the hydrologic connectivity of soil <span class="hlt">pores</span> also increases, allowing greater transport of SOC and other resources from protected locations, to microbially colonized locations more favorable to decomposition. The heterogeneous distribution of specialized decomposers, C, and other resources throughout the soil indicates that the metabolism or persistence of soil C compounds is highly dependent on short-distance transport processes. The objective of this research was to characterize the complexity of Cmore » in <span class="hlt">pore</span> waters held at weak and strong water tensions (effectively soil solution held behind coarse- and fine-<span class="hlt">pore</span> throats, respectively) and evaluate the microbial decomposability of these <span class="hlt">pore</span> waters. We saturated intact soil cores and extracted <span class="hlt">pore</span> waters with increasing suction <span class="hlt">pressures</span> to sequentially sample <span class="hlt">pore</span> waters from increasingly fine <span class="hlt">pore</span> domains. Ultrahigh resolution mass spectrometry of the SOC was used to profile the major biochemical classes (i.e., lipids, proteins, lignin, carbohydrates, and condensed aromatics) of compounds present in the <span class="hlt">pore</span> waters; some of these samples were then used as substrates for growth of Cellvibrio japonicus (DSMZ 16018), Streptomyces cellulosae (ATCC® 25439™), and Trichoderma reseei (QM6a) in 7 day incubations. The soluble C in finer <span class="hlt">pores</span> was more complex than the soluble C in coarser <span class="hlt">pores</span>, and the incubations revealed that the more complex C in these fine <span class="hlt">pores</span> is not recalcitrant. The decomposition of this complex C led to greater losses of C through respiration than the simpler C from coarser <span class="hlt">pore</span> waters. Our research suggests that soils that experience repeated cycles of drying and wetting may be accompanied by repeated cycles of increased CO2 fluxes that are driven by i) the transport of C from protected pools into</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1353307-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1353307-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains"><span>Differences in soluble organic carbon chemistry in <span class="hlt">pore</span> waters sampled from different <span class="hlt">pore</span> size domains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Bailey, V. L.; Smith, A. P.; Tfaily, M.; ...</p> <p>2017-04-01</p> <p>Spatial isolation of soil organic carbon (SOC) in different sized <span class="hlt">pores</span> may be a mechanism by which otherwise labile carbon (C) could be protected in soils. When soil water content increases, the hydrologic connectivity of soil <span class="hlt">pores</span> also increases, allowing greater transport of SOC and other resources from protected locations, to microbially colonized locations more favorable to decomposition. The heterogeneous distribution of specialized decomposers, C, and other resources throughout the soil indicates that the metabolism or persistence of soil C compounds is highly dependent on short-distance transport processes. The objective of this research was to characterize the complexity of Cmore » in <span class="hlt">pore</span> waters held at weak and strong water tensions (effectively soil solution held behind coarse- and fine-<span class="hlt">pore</span> throats, respectively) and evaluate the microbial decomposability of these <span class="hlt">pore</span> waters. We saturated intact soil cores and extracted <span class="hlt">pore</span> waters with increasing suction <span class="hlt">pressures</span> to sequentially sample <span class="hlt">pore</span> waters from increasingly fine <span class="hlt">pore</span> domains. Ultrahigh resolution mass spectrometry of the SOC was used to profile the major biochemical classes (i.e., lipids, proteins, lignin, carbohydrates, and condensed aromatics) of compounds present in the <span class="hlt">pore</span> waters; some of these samples were then used as substrates for growth of Cellvibrio japonicus (DSMZ 16018), Streptomyces cellulosae (ATCC® 25439™), and Trichoderma reseei (QM6a) in 7 day incubations. The soluble C in finer <span class="hlt">pores</span> was more complex than the soluble C in coarser <span class="hlt">pores</span>, and the incubations revealed that the more complex C in these fine <span class="hlt">pores</span> is not recalcitrant. The decomposition of this complex C led to greater losses of C through respiration than the simpler C from coarser <span class="hlt">pore</span> waters. Our research suggests that soils that experience repeated cycles of drying and wetting may result in patterns of CO2 fluxes that are driven by i) the transport of C from protected pools into active, ii) the chemical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JOM...tmp..114C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JOM...tmp..114C"><span>Dependence of CO2 Reactivity of Carbon Anodes on <span class="hlt">Pore</span> Structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Tong; Xue, Jilai; Lang, Guanghui; Liu, Rui; Gao, Shoulei; Wang, Zengjie</p> <p>2017-03-01</p> <p>The correlation between the CO2 reactivity and <span class="hlt">pore</span> structure of carbon anodes was experimentally investigated. The <span class="hlt">pore</span> structures of the anodes before and after CO2 oxidation were characterized using image analysis. The porosity, mean <span class="hlt">pore</span> diameter, and the number of micro-cracks decreased with increasing anode forming <span class="hlt">pressure</span>, while they increased with over-compaction. With prolonged CO2 oxidation time, the porosity, <span class="hlt">pore</span> density, mean <span class="hlt">pore</span> diameter, <span class="hlt">pore</span> aspect ratio, and the number of micro-cracks increased due to the merging of small <span class="hlt">pores</span>, increased <span class="hlt">pore</span> connectivity, and generation of new <span class="hlt">pores</span>. The activation energy decreased with increasing porosity of the anodes' pitch phase due to easier CO2 penetration and reaction within the anodes. The results confirm that the fine pitch-coke phase of anodes is preferentially consumed, a cause of carbon dusting. Optimization of the <span class="hlt">pore</span> structures to balance the pitch, coke, and butt phases may potentially further reduce carbon dusting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JOM....69i1600C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JOM....69i1600C"><span>Dependence of CO2 Reactivity of Carbon Anodes on <span class="hlt">Pore</span> Structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Tong; Xue, Jilai; Lang, Guanghui; Liu, Rui; Gao, Shoulei; Wang, Zengjie</p> <p>2017-09-01</p> <p>The correlation between the CO2 reactivity and <span class="hlt">pore</span> structure of carbon anodes was experimentally investigated. The <span class="hlt">pore</span> structures of the anodes before and after CO2 oxidation were characterized using image analysis. The porosity, mean <span class="hlt">pore</span> diameter, and the number of micro-cracks decreased with increasing anode forming <span class="hlt">pressure</span>, while they increased with over-compaction. With prolonged CO2 oxidation time, the porosity, <span class="hlt">pore</span> density, mean <span class="hlt">pore</span> diameter, <span class="hlt">pore</span> aspect ratio, and the number of micro-cracks increased due to the merging of small <span class="hlt">pores</span>, increased <span class="hlt">pore</span> connectivity, and generation of new <span class="hlt">pores</span>. The activation energy decreased with increasing porosity of the anodes' pitch phase due to easier CO2 penetration and reaction within the anodes. The results confirm that the fine pitch-coke phase of anodes is preferentially consumed, a cause of carbon dusting. Optimization of the <span class="hlt">pore</span> structures to balance the pitch, coke, and butt phases may potentially further reduce carbon dusting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1510181L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1510181L"><span>Electrokinetic induced solute dispersion in porous media; <span class="hlt">pore</span> network modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Shuai; Schotting, Ruud; Raoof, Amir</p> <p>2013-04-01</p> <p>Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the <span class="hlt">pore</span> scale, using a <span class="hlt">pore</span> network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single <span class="hlt">pore</span>, the average flux was obtained. Applying such single <span class="hlt">pore</span> relationships, in the thin electrical double layer limit, to each and every <span class="hlt">pore</span> within the <span class="hlt">pore</span> network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting <span class="hlt">pore</span> velocities were used to simulate solute transport within the <span class="hlt">pore</span> network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the <span class="hlt">pore</span> network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure <span class="hlt">pressure</span> driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different <span class="hlt">pore</span> coordination numbers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014WRR....50.8441M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014WRR....50.8441M"><span><span class="hlt">Pore</span> scale dynamics underlying the motion of drainage fronts in porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moebius, Franziska; Or, Dani</p> <p>2014-11-01</p> <p>Fluid displacement fronts in porous media exhibit a peculiar duality; the seemingly regular macroscopic motion of the front is propelled by numerous and irregular <span class="hlt">pore</span> scale interfacial jumps. These <span class="hlt">pore</span> scale events shape emergent front morphology, affect phase entrapment behind a front, and are likely important for colloidal mobilization and solute dispersion at the front. We present an experimental study focusing on drainage fluid front invasion dynamics through sintered glass beads using a high-speed camera and rapid capillary <span class="hlt">pressure</span> measurements to resolve <span class="hlt">pore</span> scale invasion events over a wide range of boundary conditions (flow rates and gravitational influences). We distinguished three types of "<span class="hlt">pores</span>": geometrical <span class="hlt">pores</span> deduced from image analyses; individual <span class="hlt">pore</span> invasion volumes imaged during displacement; and <span class="hlt">pore</span> volumes deduced from capillary <span class="hlt">pressure</span> fluctuations during constant withdrawal rates. The resulting <span class="hlt">pore</span> volume distributions were remarkably similar for slow drainage rates. Invaded <span class="hlt">pore</span> volumes were not affected by gravitational forces, however with increased viscous forces (higher displacement rates) the fraction of small invaded volumes increased. Capillary <span class="hlt">pressure</span> fluctuations were exponentially distributed in agreement with findings from previous studies. The distribution of <span class="hlt">pressure</span> fluctuations exhibited a distinct cutoff concurrent with the onset of simultaneous invasion events. The study highlights the different manifestation of "<span class="hlt">pores</span>" and their sensitivity to external (macroscopic) boundary conditions. The remarkable similarity of geometrical and <span class="hlt">pressure</span>-deduced <span class="hlt">pore</span> spaces offers opportunities for deducing <span class="hlt">pore</span> size distribution dynamically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDG40007S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDG40007S"><span>Modeling branching <span class="hlt">pore</span> structures in membrane filters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanaei, Pejman; Cummings, Linda J.</p> <p>2016-11-01</p> <p>Membrane filters are in widespread industrial use, and mathematical models to predict their efficacy are potentially very useful, as such models can suggest design modifications to improve filter performance and lifetime. Many models have been proposed to describe particle capture by membrane filters and the associated fluid dynamics, but most such models are based on a very simple structure in which the <span class="hlt">pores</span> of the membrane are assumed to be simple circularly-cylindrical tubes spanning the depth of the membrane. Real membranes used in applications usually have much more complex geometry, with interconnected <span class="hlt">pores</span> which may branch and bifurcate. <span class="hlt">Pores</span> are also typically larger on the upstream side of the membrane than on the downstream side. We present an idealized mathematical model, in which a membrane consists of a series of bifurcating <span class="hlt">pores</span>, which decrease in size as the membrane is traversed. Feed solution is forced through the membrane by applied <span class="hlt">pressure</span>, and particles are removed from the feed either by sieving, or by particle adsorption within <span class="hlt">pores</span> (which shrinks them). Thus the membrane's permeability decreases as the filtration progresses, ultimately falling to zero. We discuss how filtration efficiency depends on the characteristics of the branching structure. Partial support from NSF DMS 1261596 is gratefully acknowledged.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820000335&hterms=resins+surface+coatings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dresins%2Bfor%2Bsurface%2Bcoatings','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820000335&hterms=resins+surface+coatings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dresins%2Bfor%2Bsurface%2Bcoatings"><span><span class="hlt">Pressure</span> Assist Makes Coating More Reliable</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Berg, W. A.</p> <p>1983-01-01</p> <p>Applying <span class="hlt">pressure</span> improves bond between viscous coating and porous surface. <span class="hlt">Pressurization</span> forces silicone resin into <span class="hlt">pores</span> of anodized surface. Resin must completely fill <span class="hlt">pores</span> of anodized surface, or resin flakes off after put in service.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730024138','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730024138"><span>Problems of <span class="hlt">Excess</span> Capacity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Douglas, G.</p> <p>1972-01-01</p> <p>The problems of <span class="hlt">excess</span> capacity in the airline industry are discussed with focus on the following topics: load factors; fair rate of return on investment; service-quality rivalry among airlines; pricing (fare) policies; aircraft production; and the impacts of <span class="hlt">excess</span> capacity on operating costs. Also included is a discussion of the interrelationships among these topics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9215G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9215G"><span>The <span class="hlt">pore</span> space scramble</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gormally, Alexandra; Bentham, Michelle; Vermeylen, Saskia; Markusson, Nils</p> <p>2015-04-01</p> <p>Climate change and energy security continue to be the context of the transition to a secure, affordable and low carbon energy future, both in the UK and beyond. This is reflected in for example, binding climate policy targets at the EU level, the introduction of renewable energy targets, and has also led to an increasing interest in Carbon Capture and Storage (CCS) technology with its potential to help mitigate against the effects of CO2 emissions from fossil fuel burning. The UK has proposed a three phase strategy to integrate CCS into its energy system in the long term focussing on off-shore subsurface storage (DECC, 2014). The potential of CCS therefore, raises a number of challenging questions and issues surrounding the long-term storage of CO2 captured and injected into underground spaces and, alongside other novel uses of the subsurface, contributes to opening a new field for discussion on the governance of the subsurface. Such 'novel' uses of the subsurface have lead to it becoming an increasingly contested space in terms of its governance, with issues emerging around the role of ownership, liability and property rights of subsurface <span class="hlt">pore</span> space. For instance, questions over the legal ownership of <span class="hlt">pore</span> space have arisen with ambiguity over the legal standpoint of the surface owner and those wanting to utilise the <span class="hlt">pore</span> space for gas storage, and suggestions of whether there are depths at which legal 'ownership' becomes obsolete (Barton, 2014). Here we propose to discuss this '<span class="hlt">pore</span> space scramble' and provide examples of the competing trajectories of different stakeholders, particularly in the off-shore context given its priority in the UK. We also propose to highlight the current ambiguity around property law of <span class="hlt">pore</span> space in the UK with reference to approaches currently taken in different national contexts. Ultimately we delineate contrasting models of governance to illustrate the choices we face and consider the ethics of these models for the common good</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21696750','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21696750"><span>Effects of confinement on the molar enthalpy of argon adsorption in graphitic cylindrical <span class="hlt">pores</span>: a grand canonical Monte Carlo (GCMC) simulation study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Zhongjun; Do, D D; Nicholson, D</p> <p>2011-09-01</p> <p>Using a grand canonical Monte Carlo simulation, we study argon adsorption in graphitic cylindrical <span class="hlt">pores</span> to investigate the differences between the isosteric heat and the integral molar enthalpy under subcritical and supercritical conditions and compare these results against those for a flat graphite surface to investigate the role of confinement on the enthalpy change of adsorption. The isosteric heat curve is finite under subcritical conditions, but for supercritical adsorption, it becomes infinite at the <span class="hlt">pressure</span> where the <span class="hlt">excess</span> concentration versus <span class="hlt">pressure</span> is maximum. This can be circumvented using the integral molar enthalpy, which is a better variable to describe the energy change for supercritical adsorption. Finally, the effects of <span class="hlt">pore</span> geometry (radius and length) on argon adsorption under subcritical and supercritical conditions are discussed. Copyright © 2011 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2735347','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2735347"><span><span class="hlt">Excessive</span> Acquisition in Hoarding</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Frost, Randy O.; Tolin, David F.; Steketee, Gail; Fitch, Kristin E.; Selbo-Bruns, Alexandra</p> <p>2009-01-01</p> <p>Compulsive hoarding (the acquisition of and failure to discard large numbers of possessions) is associated with substantial health risk, impairment, and economic burden. However, little research has examined separate components of this definition, particularly <span class="hlt">excessive</span> acquisition. The present study examined acquisition in hoarding. Participants, 878 self-identified with hoarding and 665 family informants (not matched to hoarding participants), completed an internet survey. Among hoarding participants who met criteria for clinically significant hoarding, 61% met criteria for a diagnosis of compulsive buying and approximately 85% reported <span class="hlt">excessive</span> acquisition. Family informants indicated that nearly 95% exhibited <span class="hlt">excessive</span> acquisition. Those who acquired <span class="hlt">excessively</span> had more severe hoarding; their hoarding had an earlier onset and resulted in more psychiatric work impairment days; and they experienced more symptoms of obsessive-compulsive disorder, depression, and anxiety. Two forms of <span class="hlt">excessive</span> acquisition (buying and free things) each contributed independent variance in the prediction of hoarding severity and related symptoms. PMID:19261435</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19261435','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19261435"><span><span class="hlt">Excessive</span> acquisition in hoarding.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Frost, Randy O; Tolin, David F; Steketee, Gail; Fitch, Kristin E; Selbo-Bruns, Alexandra</p> <p>2009-06-01</p> <p>Compulsive hoarding (the acquisition of and failure to discard large numbers of possessions) is associated with substantial health risk, impairment, and economic burden. However, little research has examined separate components of this definition, particularly <span class="hlt">excessive</span> acquisition. The present study examined acquisition in hoarding. Participants, 878 self-identified with hoarding and 665 family informants (not matched to hoarding participants), completed an Internet survey. Among hoarding participants who met criteria for clinically significant hoarding, 61% met criteria for a diagnosis of compulsive buying and approximately 85% reported <span class="hlt">excessive</span> acquisition. Family informants indicated that nearly 95% exhibited <span class="hlt">excessive</span> acquisition. Those who acquired <span class="hlt">excessively</span> had more severe hoarding; their hoarding had an earlier onset and resulted in more psychiatric work impairment days; and they experienced more symptoms of obsessive-compulsive disorder, depression, and anxiety. Two forms of <span class="hlt">excessive</span> acquisition (buying and free things) each contributed independent variance in the prediction of hoarding severity and related symptoms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92a2808H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92a2808H"><span>Magnetic-resonance <span class="hlt">pore</span> imaging of nonsymmetric microscopic <span class="hlt">pore</span> shapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hertel, Stefan Andreas; Wang, Xindi; Hosking, Peter; Simpson, M. Cather; Hunter, Mark; Galvosas, Petrik</p> <p>2015-07-01</p> <p>Imaging of the microstructure of porous media such as biological tissue or porous solids is of high interest in health science and technology, engineering and material science. Magnetic resonance <span class="hlt">pore</span> imaging (MRPI) is a recent technique based on nuclear magnetic resonance (NMR) which allows us to acquire images of the average <span class="hlt">pore</span> shape in a given sample. Here we provide details on the experimental design, challenges, and requirements of MRPI, including its calibration procedures. Utilizing a laser-machined phantom sample, we present images of microscopic <span class="hlt">pores</span> with a hemiequilateral triangular shape even in the presence of NMR relaxation effects at the <span class="hlt">pore</span> walls. We therefore show that MRPI is applicable to porous samples without a priori knowledge about their <span class="hlt">pore</span> shape and symmetry. Furthermore, we introduce "MRPI mapping," which combines MRPI with conventional magnetic resonance imaging (MRI). This enables one to resolve microscopic <span class="hlt">pore</span> sizes and shapes spatially, thus expanding the application of MRPI to samples with heterogeneous distributions of <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1484239','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1484239"><span>Model <span class="hlt">Pores</span> of Molecular Dimension</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Quinn, J. A.; Anderson, J. L.; Ho, W. S.; Petzny, W. J.</p> <p>1972-01-01</p> <p>Extremely uniform <span class="hlt">pores</span> of near molecular dimension can be formed by the irradiation-etching technique first demonstrated by Price and Walker. The technique has now been developed to the stage where it can be used to fabricate model membranes for examining the various steric, hydrodynamic, and electrodynamic phenomena encountered in transport through molecular-size <span class="hlt">pores</span>. Methods for preparing and characterizing membranes with <span class="hlt">pores</span> as small as 25 A (radius) are described in this paper. Results on <span class="hlt">pore</span> size determination via Knudsen gas flow and electrolyte conduction are compared. <span class="hlt">Pore</span> wall modification by monolayer deposition is also discussed. PMID:4339801</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1213014P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1213014P"><span>Soils, <span class="hlt">Pores</span>, and NMR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Haber, Agnes; Sucre, Oscar; Stingaciu, Laura; Stapf, Siegfried; Blümich, Bernhard</p> <p>2010-05-01</p> <p>Within Cluster A, Partial Project A1, the <span class="hlt">pore</span> space exploration by means of Nuclear Magnetic Resonance (NMR) plays a central role. NMR is especially convenient since it probes directly the state and dynamics of the substance of interest: water. First, NMR is applied as relaxometry, where the degree of saturation but also the <span class="hlt">pore</span> geometry controls the NMR signature of natural porous systems. Examples are presented where soil samples from the Selhausen, Merzenhausen (silt loams), and Kaldenkirchen (sandy loam) test sites are investigated by means of Fast Field Cycling Relaxometry at different degrees of saturation. From the change of the relaxation time distributions with decreasing water content and by comparison with conventional water retention curves we conclude that the fraction of immobile water is characterized by T1 < 5 ms. Moreover, the dependence of the relaxation rate on magnetic field strength allows the identification of 2D diffusion at the interfaces as the mechanism which governs the relaxation process (Pohlmeier et al. 2009). T2 relaxation curves are frequently measured for the rapid characterization of soils by means of the CPMG echo train. Basically, they contain the same information about the <span class="hlt">pore</span> systems like T1 curves, since mostly the overall relaxation is dominated by surface relaxivity and the surface/volume ratio of the <span class="hlt">pores</span>. However, one must be aware that T2 relaxation is additionally affected by diffusion in internal gradients, and this can be overcome by using sufficiently short echo times and low magnetic fields (Stingaciu et al. 2009). Second, the logic continuation of conventional relaxation measurements is the 2-dimensional experiment, where prior to the final detection of the CPMG echo train an encoding period is applied. This can be T1-encoding by an inversion pulse, or T2 encoding by a sequence of 90 and 180° pulses. During the following evolution time the separately encoded signals can mix and this reveals information about</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MMTA...45.4002J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MMTA...45.4002J"><span>Finite Element and Experimental Analysis of Closure and Contact Bonding of <span class="hlt">Pores</span> During Hot Rolling of Steel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Joo, Soo-Hyun; Jung, Jaimyun; Chun, Myung Sik; Moon, Chang Ho; Lee, Sunghak; Kim, Hyoung Seop</p> <p>2014-08-01</p> <p>The closure and contact bonding behavior of internal <span class="hlt">pores</span> in steel slabs during hot rolling was studied using experiments and the finite element method (FEM). Effects of <span class="hlt">pore</span> size and shape were investigated, and three different cases of <span class="hlt">pore</span> closure results were observed: no closure, partial closure, and full closure. The FEM results well reproduced various closure events. Bonding strengths of unsuccessfully closed <span class="hlt">pores</span>, measured by tensile tests, showed critical effects. Also, there was a difference in bonding strengths of several fully closed <span class="hlt">pores</span>. Fracture surfaces showed that welded regions could be divided into three (not, partially, and perfectly) welded regions. The <span class="hlt">pressure</span>-time curves obtained from the FEM results indicate that <span class="hlt">pore</span> surface contact time and deformed surface length are important parameters in <span class="hlt">pore</span> welding. <span class="hlt">Pore</span> size, <span class="hlt">pore</span> shape, time of <span class="hlt">pressure</span> contact, and deformed surface length should be considered to completely eliminate <span class="hlt">pores</span> in final products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.aad.org/public/diseases/dry-sweaty-skin/hyperhidrosis','NIH-MEDLINEPLUS'); return false;" href="https://www.aad.org/public/diseases/dry-sweaty-skin/hyperhidrosis"><span>Hyperhidrosis (<span class="hlt">Excessive</span> Sweating)</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... a cause (Alzheimer’s Association) Iontophoresis (the no-sweat machine) If <span class="hlt">excessive</span> sweating affects your hands, feet, or ... this is an option, the dermatologist uses a machine that emits electromagnetic energy. This energy destroys the ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27976762','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27976762"><span>The total and the differential mean <span class="hlt">pore</span> anisotropy in porous solids and the ranking of <span class="hlt">pores</span> according to Zipf's law.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Margellou, Antigoni; Pomonis, Philippos</p> <p>2017-01-04</p> <p>In this work the property of total <span class="hlt">pore</span> anisotropy in porous solids is introduced. Its calculation is based on a combination of the specific surface area Sp and the specific <span class="hlt">pore</span> volume Vp estimated via typical nitrogen porosimetry data and tested in two kinds of porous materials: a group of spinels CoAl2O4 with differentiated random porosities and a second group of silicas SiO2 with ordered porosity modulated by the addition of LaFeO3 nanoparticles. Two basic complementary expressions of total <span class="hlt">pore</span> anisotropy were estimated: (i) the specific total mean <span class="hlt">pore</span> anisotropy bmean,total = (N·b) ≈ [Sp(3)]/[Vp(2)] corresponding to the total anisotropy value of all N hypothetical similar <span class="hlt">pores</span> in one gram of a solid with mean size Dmean = 4Vp/Sp and anisotropy b = Ltotal/Dmean. The bmean,total takes a unique value for each particular porous material. (ii) The specific differential mean <span class="hlt">pore</span> anisotropies bmean,diff = (Ni·bi) ≈ [Spi(3)]/[Vpi(2)] corresponding to the spectrum of partial anisotropy values bmean,diff = Li/Di of Ni <span class="hlt">pores</span> with similar size Di = 4Vi/Si possessing differential <span class="hlt">pore</span> volume Vpi and differential specific surface area Spi. The bmean diff takes different values at each particular partial <span class="hlt">pressure</span> and exhibits a distribution as a function of <span class="hlt">pore</span> radius bmean,diff = f(ri). It is shown that plots of log(bmean,diff) = f(log(ri)) lead to the ranking of <span class="hlt">pores</span> according to the Zipf's law log(Ni) = A - B log(Vpi). This ranking is not obeyed by the <span class="hlt">pores</span> exhibiting appreciable local <span class="hlt">pore</span> anisotropy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830001864','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830001864"><span><span class="hlt">Pore</span> size engineering applied to starved electrochemical cells and batteries</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abbey, K. M.; Thaller, L. H.</p> <p>1982-01-01</p> <p>To maximize performance in starved, multiplate cells, the cell design should rely on techniques which widen the volume tolerance characteristics. These involve engineering capillary <span class="hlt">pressure</span> differences between the components of an electrochemical cell and using these forces to promote redistribution of electrolyte to the desired optimum values. This can be implemented in practice by prescribing <span class="hlt">pore</span> size distributions for porous back-up plates, reservoirs, and electrodes. In addition, electrolyte volume management can be controlled by incorporating different <span class="hlt">pore</span> size distributions into the separator. In a nickel/hydrogen cell, the separator must contain <span class="hlt">pores</span> similar in size to the small <span class="hlt">pores</span> of both the nickel and hydrogen electrodes in order to maintain an optimum conductive path for the electrolyte. The <span class="hlt">pore</span> size distributions of all components should overlap in such a way as to prevent drying of the separator and/or flooding of the hydrogen electrode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJST.223.1813G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJST.223.1813G"><span><span class="hlt">Pore</span> dynamics in lipid membranes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gozen, I.; Dommersnes, P.</p> <p>2014-09-01</p> <p>Transient circular <span class="hlt">pores</span> can open in plasma membrane of cells due to mechanical stress, and failure to repair such <span class="hlt">pores</span> lead to cell death. Similar <span class="hlt">pores</span> in the form of defects also exist among smectic membranes, such as in myelin sheaths or mitochondrial membranes. The formation and growth of membrane defects are associated with diseases, for example multiple sclerosis. A deeper understanding of membrane <span class="hlt">pore</span> dynamics can provide a more refined picture of membrane integrity-related disease development, and possibly also treatment options and strategies. <span class="hlt">Pore</span> dynamics is also of great importance regarding healthcare applications such as drug delivery, gene or as recently been implied, cancer therapy. The dynamics of <span class="hlt">pores</span> significantly differ in stacks which are confined in 2D compared to those in cells or vesicles. In this short review, we will summarize the dynamics of different types of <span class="hlt">pores</span> that can be observed in biological membranes, which include circular transient, fusion and hemi-fusion <span class="hlt">pores</span>. We will dedicate a section to floral and fractal <span class="hlt">pores</span> which were discovered a few years ago and have highly peculiar characteristics. Finally, we will discuss the repair mechanisms of large area <span class="hlt">pores</span> in conjunction with the current cell membrane repair hypotheses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6480817','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6480817"><span>Experimental evidence of homogeneous superfluid turbulence in large-<span class="hlt">pore</span> porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Maddocks, J.R.; Van Sciver, S.W. )</p> <p>1994-09-01</p> <p>Experimental results are presented for counterflow and isothermal coflow through large-<span class="hlt">pore</span> porous materials, with porosities greater than 90% and permeabilities of order 10[sup [minus]11] m[sup 2]. Counterflow velocities ranging from 0.06 to 0.14 m/s were obtained. Because of the large-<span class="hlt">pore</span> geometry, and the velocity range investigated, the superfluid is fully turbulent. The counterflow data are well described by the two-fluid model using the Schwarz model of homogeneous mutual friction, with a larger, empirically-modified, mutual friction coefficient. The same mutual friction model is applied to the coflow results, assuming that dissipation due to superfluid vortex interaction with the wall of the porous media is negligible. In this case, the normal-fluid and superfluid velocities are coupled through the mutual friction, and relative velocities in the range 0.00 to 0.10 m/s, the authors calculate relative velocities up to 0.07 m/s, and normal-fluid velocities in <span class="hlt">excess</span> of 0.04 m/s. An interesting feature of the coflow <span class="hlt">pressure</span> drop, as a function of the normal-fluid velocity, is that it is larger than the counterflow <span class="hlt">pressure</span> drop by the ratio of the total density to the normal-fluid density.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.H43J..02L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.H43J..02L"><span>Drainage Studies Using <span class="hlt">Pore</span>-Scale Approaches</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, E. B.; Reed, A. H.; Hilpert, M.</p> <p>2007-12-01</p> <p>The process of drainage has wide spread applications in soil hydrology, irrigation, and the remediation of contaminants in the subsurface. In this paper, we present the comparison of experimental and <span class="hlt">pore</span>-scale modeling results for drainage. Using a HD-500 microCT system, X-ray tomographic images (21 micron voxels) of saturation during a drainage experiment were obtained in a porous medium consisting of 20/30 mesh (590- 840 microns) Accusand. Utilizing the segmented microtomographic images of the <span class="hlt">pore</span> space, we modeled drainage using two <span class="hlt">pore</span>-scale approaches: (1) the <span class="hlt">pore</span>-morphology-based simulator (PMBS) developed by Hilpert and Miller (2001), and (2) a Lattice Boltzmann (LB) model. Invasion pathways and <span class="hlt">pressure</span>-saturation relations obtained from both the PMBS and the LB model were compared with those obtained from experiments. The results of PMBS modeling displayed good agreement with experimental observations, except at high suction and low water saturation values, where both CT resolution and model assumptions become an issue. The LB model is currently being refined, and the results of these simulations will also be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19366586','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19366586"><span>Extrusion of transmitter, water and ions generates forces to close fusion <span class="hlt">pore</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tajparast, M; Glavinović, M I</p> <p>2009-05-01</p> <p>During exocytosis the fusion <span class="hlt">pore</span> opens rapidly, then dilates gradually, and may subsequently close completely, but what controls its dynamics is not well understood. In this study we focus our attention on forces acting on the <span class="hlt">pore</span> wall, and which are generated solely by the passage of transmitter, ions and water through the open fusion <span class="hlt">pore</span>. The transport through the charged cylindrical nano-size <span class="hlt">pore</span> is simulated using a coupled system of Poisson-Nernst-Planck and Navier-Stokes equations and the forces that act radially on the wall of the fusion <span class="hlt">pore</span> are then estimated. Four forces are considered: a) inertial force, b) <span class="hlt">pressure</span>, c) viscotic force, and d) electrostatic force. The inertial and viscotic forces are small, but the electrostatic force and the <span class="hlt">pressure</span> are typically significant. High vesicular <span class="hlt">pressure</span> tends to open the fusion <span class="hlt">pore</span>, but the <span class="hlt">pressure</span> induced by the transport of charged particles (glutamate, ions), which is predominant when the <span class="hlt">pore</span> wall charge density is high tends to close the <span class="hlt">pore</span>. The electrostatic force, which also depends on the charge density on the <span class="hlt">pore</span> wall, is weakly repulsive before the <span class="hlt">pore</span> dilates, but becomes attractive and pronounced as the <span class="hlt">pore</span> dilates. Given that the vesicular concentration of free transmitter can change rapidly due to the release, or owing to the dissociation from the gel matrix, we evaluated how much and how rapidly a change of the vesicular K(+)-glutamate(-) concentration affects the concentration of glutamate(-) and ions in the <span class="hlt">pore</span> and how such changes alter the radial force on the wall of the fusion <span class="hlt">pore</span>. A step-like rise of the vesicular K(+)-glutamate(-) concentration leads to a chain of events. <span class="hlt">Pore</span> concentration (and efflux) of both K(+) and glutamate(-) rise reaching their new steady-state values in less than 100 ns. Interestingly within a similar time interval the <span class="hlt">pore</span> concentration of Na(+) also rises, whereas that of Cl(-) diminishes, although their extra-cellular concentration does not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19..386R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19..386R"><span>Size dependent <span class="hlt">pore</span> size distribution of shales by gas physisorption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roshan, Hamid; Andersen, Martin S.; Yu, Lu; Masoumi, Hossein; Arandian, Hamid</p> <p>2017-04-01</p> <p>Gas physisorption, in particular nitrogen adsorption-desorption, is a traditional technique for characterization of geomaterials including the organic rich shales. The low <span class="hlt">pressure</span> nitrogen is used together with adsorption-desorption physical models to study the <span class="hlt">pore</span> size distribution (PSD) and porosity of the porous samples. The samples are usually crushed to a certain fragment size to measure these properties however there is not yet a consistent standard size proposed for sample crushing. Crushing significantly increases the surface area of the fragments e.g. the created surface area is differentiated from that of <span class="hlt">pores</span> using BET technique. In this study, we show that the smaller fragment sizes lead to higher cumulative <span class="hlt">pore</span> volume and smaller <span class="hlt">pore</span> diameters. It is also shown that some of the micro-<span class="hlt">pores</span> are left unaccounted because of the correction of the external surface area. In order to illustrate this, the nitrogen physisorption is first conducted on the identical organic rich shale samples with different sizes: 20-25, 45-50 and 63-71 µm. We then show that such effects are not only a function of <span class="hlt">pore</span> structure changes induced by crushing, but is linked to the inability of the physical models in differentiating between the external surface area (BET) and micro-<span class="hlt">pores</span> for different crushing sizes at relatively low nitrogen <span class="hlt">pressure</span>. We also discuss models currently used in nano-technology such as t-method to address this issue and their advantages and shortcoming for shale rock characterization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCrGr.460..126W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCrGr.460..126W"><span>Effects of supersaturation on <span class="hlt">pore</span> shape in solid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, P. S.; Hsiao, S. Y.</p> <p>2017-02-01</p> <p>The shape of a <span class="hlt">pore</span> resulting from a bubble entrapped by a solidification front with different supersaturation ratios is predicted in this work. Supersaturation ratio, representing the ratio between solute concentration and saturation solute concentration, determines nucleation of a bubble and development of the <span class="hlt">pore</span> shape in the early stage. <span class="hlt">Pore</span> formation and its shape in solid influence contemporary issues of biology, engineering, foods, geophysics and climate change, etc. This work extends and combines previous models accounting for realistic mass and momentum transport, and physico-chemical equilibrium of solute gas across the bubble cap to self-consistently determine shape of the bubble cap beyond the solidification front and the <span class="hlt">pore</span> shape in solid. The study also deal with that <span class="hlt">pore</span> formation can be resulted from three different mechanisms, depending on the directions and magnitude of solute gas transport across the bubble cap. Case 1 is subject to solute transport from the <span class="hlt">pore</span> across the cap into the surrounding liquid in the early stage. Cases 2a and 2b indicate opposite direction of solute transport. In contrast to Case 2b, the effect of solute transport on solute gas <span class="hlt">pressure</span> in the <span class="hlt">pore</span> in Case 2a is stronger than that of <span class="hlt">pore</span> volume expansionin the last stage. The results find that an increase in supersaturation ratio decreases <span class="hlt">pore</span> radius and time for bubble entrapment in Case 1. The bubble cannot be entrapped in Case 2. The predicted <span class="hlt">pore</span> shape in solid agrees with experimental data. Understanding, prediction and control of the growth of the <span class="hlt">pore</span> shape have therefore been obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/161840','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/161840"><span><span class="hlt">Pore</span> size and <span class="hlt">pore</span> throat types in a heterogeneous dolostone reservoir, Devonian Grosmont formation, western Canada sedimentary basin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Luo, P.; Machel, H. G.</p> <p>1995-11-01</p> <p>The Devonian Grosmont Formation in northeastern Alberta, Canada, is a giant heavy-oil reservoir. The main reservoir rocks are dolomitized and karstified platform and ramp carbonates, and the best reservoir facies occur in the upper Grosmont (UGM) units 3 and 2. In these units, reservoir properties are highly heterogeneous. Hand specimen, thin section, UV, and SEM petrography, as well as grading scales, mercury capillary <span class="hlt">pressure</span> curve analysis, and statistics, have been used to characterize reservoir heterogeneity. Our investigation led to a new <span class="hlt">pore</span> size classification for carbonate reservoirs; this new classification has four <span class="hlt">pore</span> sizes: microporosity (<span class="hlt">pore</span> diameters <1 {mu}m), mesoporosity (<span class="hlt">pore</span> diameters 1-1000 {mu}m), macroporosity (<span class="hlt">pore</span> diameters 1-256 mm), and megaporosity (<span class="hlt">pore</span> diameters >256 mm). A combination of microscopic observations and capillary <span class="hlt">pressure</span> curve characteristics led to the recognition of four <span class="hlt">pore</span> throat texture types on the microporosity scale, and to five types on the mesoporosity scale. Microporosity <span class="hlt">pore</span> types include (1) intracrystal dissolution porosity, (2) pervasive intercrystal and intracrystal dissolution porosity, (3) intergranular and/or intercrystal porosity in grainstones, and (4) primary or solution microporosity in mud matrix (only in limestones). Mesoporosity <span class="hlt">pore</span> types include (1) intercrystal porosity, (2) solution-enhanced intercrystal porosity, (3) oversized porosity, (4) intragranular solution porosity, and (5) intergranular solution porosity. Some of these types are homogeneous (e.g., non-fabric selective dissolution porosity and intercrystal primary porosity), whereas others are heterogeneous. Generally, hydrocarbon recovery efficiency is good in the homogeneous <span class="hlt">pore</span> throat types, but poor in the heterogeneous types.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3942180','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3942180"><span>Nonaccommodative convergence <span class="hlt">excess</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>von Noorden, G K; Avilla, C W</p> <p>1986-01-15</p> <p>Nonaccommodative convergence <span class="hlt">excess</span> is a condition in which a patient has orthotropia or a small-angle esophoria or esotropia at distance and a large-angle esotropia at near, not significantly reduced by the addition of spherical plus lenses. The AC/A ratio, determined with the gradient method, is normal or subnormal. Tonic convergence is suspected of causing the convergence <span class="hlt">excess</span> in these patients. Nonaccommodative convergence <span class="hlt">excess</span> must be distinguished from esotropia with a high AC/A ratio and from hypoaccommodative esotropia. In 24 patients treated with recession of both medial recti muscles with and without posterior fixation or by posterior fixation alone, the mean correction of esotropia was 7.4 prism diopters at distance and 17 prism diopters at near.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4540421','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4540421"><span>Nanometer-Scale <span class="hlt">Pore</span> Characteristics of Lacustrine Shale, Songliao Basin, NE China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Min; Yang, Jinxiu; Wang, Zhiwei; Lu, Shuangfang</p> <p>2015-01-01</p> <p>In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale <span class="hlt">pores</span> or fractures, so the <span class="hlt">pore</span> types and PSDs (<span class="hlt">pore</span> size distributions) play a major role in the shale oil occurrence (free or absorbed state), amount of oil, and flow features. The <span class="hlt">pore</span> types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale <span class="hlt">pores</span> and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope) observations, low <span class="hlt">pressure</span> CO2 and N2 adsorption, and high-<span class="hlt">pressure</span> mercury injection experiments. Analysis results indicate that: (1) <span class="hlt">Pore</span> types in the lacustrine shale include inter-matrix <span class="hlt">pores</span>, intergranular <span class="hlt">pores</span>, organic matter <span class="hlt">pores</span>, and dissolution <span class="hlt">pores</span>, and these <span class="hlt">pores</span> are dominated by mesopores and micropores; (2) There is no apparent correlation between <span class="hlt">pore</span> volumes and clay content, however, a weak negative correlation is present between total <span class="hlt">pore</span> volume and carbonate content; (3) <span class="hlt">Pores</span> in lacustrine shale are well developed when the organic matter maturity (Ro) is >1.0% and the <span class="hlt">pore</span> volume is positively correlated with the TOC (total organic carbon) content. The statistical results suggest that oil in lacustrine shale mainly occurs in <span class="hlt">pores</span> with diameters larger than 40 nm. However, more research is needed to determine whether this minimum <span class="hlt">pore</span> diameter for oil occurrence in lacustrine shale is widely applicable. PMID:26285123</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26285123','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26285123"><span>Nanometer-Scale <span class="hlt">Pore</span> Characteristics of Lacustrine Shale, Songliao Basin, NE China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Min; Yang, Jinxiu; Wang, Zhiwei; Lu, Shuangfang</p> <p>2015-01-01</p> <p>In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale <span class="hlt">pores</span> or fractures, so the <span class="hlt">pore</span> types and PSDs (<span class="hlt">pore</span> size distributions) play a major role in the shale oil occurrence (free or absorbed state), amount of oil, and flow features. The <span class="hlt">pore</span> types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale <span class="hlt">pores</span> and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope) observations, low <span class="hlt">pressure</span> CO2 and N2 adsorption, and high-<span class="hlt">pressure</span> mercury injection experiments. Analysis results indicate that: (1) <span class="hlt">Pore</span> types in the lacustrine shale include inter-matrix <span class="hlt">pores</span>, intergranular <span class="hlt">pores</span>, organic matter <span class="hlt">pores</span>, and dissolution <span class="hlt">pores</span>, and these <span class="hlt">pores</span> are dominated by mesopores and micropores; (2) There is no apparent correlation between <span class="hlt">pore</span> volumes and clay content, however, a weak negative correlation is present between total <span class="hlt">pore</span> volume and carbonate content; (3) <span class="hlt">Pores</span> in lacustrine shale are well developed when the organic matter maturity (Ro) is >1.0% and the <span class="hlt">pore</span> volume is positively correlated with the TOC (total organic carbon) content. The statistical results suggest that oil in lacustrine shale mainly occurs in <span class="hlt">pores</span> with diameters larger than 40 nm. However, more research is needed to determine whether this minimum <span class="hlt">pore</span> diameter for oil occurrence in lacustrine shale is widely applicable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913012W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913012W"><span>Analogue modelling of caprock failure and sediment mobilisation due to <span class="hlt">pore</span> fluid overpressure in shallow reservoirs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Warsitzka, Michael; Kukowski, Nina; May, Franz</p> <p>2017-04-01</p> <p>Injection of CO2 in geological formations may cause <span class="hlt">excess</span> <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> by enhancing the fluid volume in the reservoir rock and by buoyancy-driven flow. If sediments in the reservoir and the caprock are undercompacted, <span class="hlt">pore</span> fluid overpressure can lead to hydro-fractures in the caprock and fluidisation of sediments. Eventually, these processes trigger the formation of pipe structures, gas chimneys, gas domes or sand injections. Generally, such structures serve as high permeable pathways for fluid migration through a low-permeable seal layer and have to be considered in risk assessment or modelling of caprock integrity of CO2 storage sites. We applied scaled analogue experiments to characterise and quantify mechanisms determining the onset and migration of hydro-fractures in a low-permeable, cohesive caprock and fluidisation of unconsolidated sediments of the reservoir layer. The caprock is simulated by different types of cohesive powder. The reservoir layer consists of granulates with small particle density. Air injected through the base of the experiment and additionally through a single needle valve reaching into the analogue material is applied to generate fluid <span class="hlt">pressure</span> within the materials. With this procedure, regional fluid <span class="hlt">pressure</span> increase or a point-like local fluid <span class="hlt">pressure</span> increase (e.g. injection well), respectively, can be simulated. The deformation in the analogue materials is analysed with a particle tracking imaging velocimetry technique. <span class="hlt">Pressure</span> sensors at the base of the experiment and in the needle valve record the air <span class="hlt">pressure</span> during an experimental run. The structural evolution observed in the experiments reveal that the cohesive cap rock first forms a dome-like anticline. Extensional fractures occur at the hinges of the anticline. A further increase of fluid <span class="hlt">pressure</span> causes a migration of this fractures towards the surface, which is followed by intrusion of reservoir material into the fractures and the collapse of the anticline. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013CG.....61..160R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CG.....61..160R"><span><span class="hlt">Pore</span>Flow: A complex <span class="hlt">pore</span>-network model for simulation of reactive transport in variably saturated porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raoof, A.; Nick, H. M.; Hassanizadeh, S. M.; Spiers, C. J.</p> <p>2013-12-01</p> <p>This study introduces <span class="hlt">Pore</span>Flow, a <span class="hlt">pore</span>-network modeling tool capable of simulating fluid flow and multi-component reactive and adsorptive transport under saturated and variably saturated conditions. <span class="hlt">Pore</span>Flow includes a variety of modules, such as: <span class="hlt">pore</span> network generator, drainage simulator, calculation of <span class="hlt">pressure</span> and velocity distributions, and modeling of reactive solute transport accounting for advection and diffusion. The <span class="hlt">pore</span> space is represented using a multi-directional <span class="hlt">pore</span>-network capable of capturing the random structure of a given porous media with user-defined directional connectivities for anisotropic <span class="hlt">pore</span> structures. The chemical reactions can occur within the liquid phase, as well as between the liquid and solid phases which may result in an evolution of porosity and permeability. Under variably saturated conditions the area of interfaces changes with degree of the fluid saturation. <span class="hlt">Pore</span>Flow uses complex formulations for more accurate modeling of transport problems in presence of the nonwetting phase. This is done by refining the discretization within drained <span class="hlt">pores</span>. An implicit numerical scheme is used to solve the governing equations, and an efficient substitution method is applied to considerably minimize computational times. Several examples are provided, under saturated and variably saturated conditions, to demonstrate the model applicability in hydrogeology problems and petroleum fields. We show that <span class="hlt">Pore</span>Flow is a powerful tool for upscaling of flow and transport in porous media, utilizing different <span class="hlt">pore</span> scale information such as various interfaces, phase distributions and local fluxes and concentrations to determine macro scale properties such as average saturation, relative permeability, solute dispersivity, adsorption coefficients, effective diffusion and tortuosity. Such information can be used as constitutive relations within continuum scale governing equations to model physical and chemical processes more accurately at the larger scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B13B0629M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B13B0629M"><span>The Water Retention Curves in THF Hydrate-Bearing Sediments - Experimental Measurement and <span class="hlt">Pore</span> Scale Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahabadi, N.; Zheng, X.; Dai, S.; Seol, Y.; Zapata, C.; Yun, T.; Jang, J.</p> <p>2015-12-01</p> <p>The water retention curve (WRC) of hydrate-bearing sediments is critically important to understand the behaviour of hydrate dissociation for gas production. Most gas hydrates in marine environment have been formed from an aqueous phase (gas-dissolved water). However, the gas hydrate formation from an aqueous phase in a laboratory requires long period due to low gas solubility in water and is also associated with many experimental difficulties such as hydrate dissolution, difficult hydrate saturation control, and dynamic hydrate dissolution and formation. In this study, tetrahydrofuran (THF) is chosen to form THF hydrate because the formation process is faster than gas hydrate formation and hydrate saturation is easy to control. THF hydrate is formed at water-<span class="hlt">excess</span> condition. Therefore, there is only water in the <span class="hlt">pore</span> space after a target THF hydrate saturation is obtained. The <span class="hlt">pore</span> habit of THF hydrate is investigated by visual observation in a transparent micromodel and X-ray computed tomography images; and the water retention curves are obtained under different THF hydrate saturation conditions. Targeted THF hydrate saturations are Sh=0, 0.2, 0.4, 0.6 and 0.8. Results shown that at a given water saturation the capillary <span class="hlt">pressure</span> increases as THF hydrate saturation increases. And the gas entry <span class="hlt">pressure</span> increases with increasing hydrate saturation. The WRC obtained by experiments is also compared with the results of a <span class="hlt">pore</span>-network model simulation and Lattice Boltzmann Method. The fitting parameters of van Genuchten equation for different hydrate saturation conditions are suggested for the use as input parameters of reservoir simulators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/916936','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/916936"><span>Effects of <span class="hlt">pore</span> size on the adsorption of hydrogen in slit <span class="hlt">pores</span> of constant width and varying height</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Culp, J.T.; Natesakhawat, S.; Smith, M.R.; Bittner, E.W.; Matranga, C.S.; Bockrath, B.C.</p> <p>2007-08-01</p> <p>The effects of <span class="hlt">pore</span> size on the hydrogen storage properties of a series of pillared layered solids were investigated at 77 K and 87 K up to a <span class="hlt">pressure</span> of 1 atm. The isotherms were fit to the Langmuir-Freundlich equation and extrapolated to determine saturation values. The materials studied are based on the M(L)[M'(CN)4] structural motif, where M = Co or Ni, L = pyrazine (pyz), 4,4'bipyridine (bpy) or 4,4'-dipyridylacetylene (dpac), and M' = Ni, Pd or Pt. The compounds all possess slit like <span class="hlt">pores</span> with constant inplane dimensions and <span class="hlt">pore</span> heights that vary as a function of (L). The pyz pillared materials with the smallest <span class="hlt">pore</span> dimensions store hydrogen at a <span class="hlt">pore</span> density similar to the bulk liquid. The adsorbed hydrogen density drops by a factor of two as the relative <span class="hlt">pore</span> size is tripled in the dpac material. The decreased storage efficiency diminishes the expected gravimetric gain in capacity for the larger <span class="hlt">pore</span> materials. The heats of adsorption were found to range from 6 to 8 kJ/mol in the series, and weakly correlate with <span class="hlt">pore</span> size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25245282','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25245282"><span>Velocity profiles in <span class="hlt">pores</span> with undulating opening diameter and their importance for resistive-pulse experiments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Innes, Laura M; Chen, Chin-Hsuan; Schiel, Matthew; Pevarnik, Matthew; Haurais, Florian; Toimil-Molares, Maria Eugenia; Vlassiouk, Ivan; Theogarajan, Luke; Siwy, Zuzanna S</p> <p>2014-10-21</p> <p><span class="hlt">Pores</span> with undulating opening diameters have emerged as an analytical tool enhancing the speed of resistive-pulse experiments, with a potential to simultaneously characterize size and mechanical properties of translocating objects. In this work, we present a detailed study of the characteristics of resistive-pulses of charged and uncharged polymer particles in <span class="hlt">pores</span> with different aspect ratios and <span class="hlt">pore</span> topography. Although no external <span class="hlt">pressure</span> difference was applied, our experiments and modeling indicated the existence of local <span class="hlt">pressure</span> drops, which modified axial and radial velocities of the solution. As a consequence of the complex velocity profiles, <span class="hlt">pores</span> with undulating <span class="hlt">pore</span> diameter and low-aspect ratio exhibited large dispersion of the translocation times. Distribution of the pulse amplitude, which is a measure of the object size, was not significantly affected by the <span class="hlt">pore</span> topography. The importance of tuning <span class="hlt">pore</span> geometry for the application in resistive-sensing and multipronged characterization of physical properties of translocating objects is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.cancer.gov/news-events/press-releases/2015/hiv-excess-cancers-jnci','NCI'); return false;" href="https://www.cancer.gov/news-events/press-releases/2015/hiv-excess-cancers-jnci"><span>HIV <span class="hlt">Excess</span> Cancers JNCI</span></a></p> <p><a target="_blank" href="http://www.cancer.gov">Cancer.gov</a></p> <p></p> <p></p> <p>In 2010, an estimated 7,760 new cancers were diagnosed among the nearly 900,000 Americans known to be living with HIV infection. According to the first comprehensive study in the United States, approximately half of these cancers were in <span class="hlt">excess</span> of what wo</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11177517','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11177517"><span>Addiction as <span class="hlt">excessive</span> appetite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Orford, J</p> <p>2001-01-01</p> <p>The <span class="hlt">excessive</span> appetite model of addiction is summarized. The paper begins by considering the forms of <span class="hlt">excessive</span> appetite which a comprehensive model should account for: principally, <span class="hlt">excessive</span> drinking, smoking, gambling, eating, sex and a diverse range of drugs including at least heroin, cocaine and cannabis. The model rests, therefore, upon a broader concept of what constitutes addiction than the traditional, more restricted, and arguably misleading definition. The core elements of the model include: very skewed consumption distribution curves; restraint, control or deterrence; positive incentive learning mechanisms which highlight varied forms of rapid emotional change as rewards, and wide cue conditioning; complex memory schemata; secondary, acquired emotional regulation cycles, of which 'chasing', 'the abstinence violation effect' and neuroadaptation are examples; and the consequences of conflict. These primary and secondary processes, occurring within diverse sociocultural contexts, are sufficient to account for the development of a strong attachment to an appetitive activity, such that self-control is diminished, and behaviour may appear to be disease-like. Giving up <span class="hlt">excess</span> is a natural consequence of conflict arising from strong and troublesome appetite. There is much supportive evidence that change occurs outside expert treatment, and that when it occurs within treatment the change processes are more basic and universal than those espoused by fashionable expert theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993REDS..126..409Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993REDS..126..409Y"><span>Stimulus-responsive track <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshida, Masaru; Tamada, Masao; Asano, Masaharu; Omichi, Hideki; Kubota, Hitoshi; Katakai, Ryoichi; Spohr, Reimar; Vetter, Johann</p> <p>1993-03-01</p> <p>Ion track grafting enables the manufacture of chemically responsive track <span class="hlt">pores</span> analogous to the discrete membrane channels found in biology. For this purpose etched ion tracks generated in CR-39 are surface-grafted by methacryloyl-L-alaninemethylester. In the future, the responsive track <span class="hlt">pores</span> could be used to model the actively controlled channels in biomembranes and may lead to interesting technological applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18430702','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18430702"><span>The otherness of sexuality: <span class="hlt">excess</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stein, Ruth</p> <p>2008-03-01</p> <p>The present essay, the second of a series of three, aims at developing an experience-near account of sexuality by rehabilitating the idea of <span class="hlt">excess</span> and its place in sexual experience. It is suggested that various types of <span class="hlt">excess</span>, such as <span class="hlt">excess</span> of excitation (Freud), the <span class="hlt">excess</span> of the other (Laplanche), <span class="hlt">excess</span> beyond symbolization and the <span class="hlt">excess</span> of the forbidden object of desire (Leviticus; Lacan) work synergistically to constitute the compelling power of sexuality. In addition to these notions, further notions of <span class="hlt">excess</span> touch on its transformative potential. Such notions address <span class="hlt">excess</span> that shatters psychic structures and that is actively sought so as to enable new ones to evolve (Bersani). Work is quoted that regards <span class="hlt">excess</span> as a way of dealing with our lonely, discontinuous being by using the "<span class="hlt">excessive</span>" cosmic energy circulating through us to achieve continuity against death (Bataille). Two contemporary analytic thinkers are engaged who deal with the object-relational and intersubjective vicissitudes of <span class="hlt">excess</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/43093','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/43093"><span><span class="hlt">Excess</span> and unlike interaction second virial coefficients and <span class="hlt">excess</span> enthalpy of mixing of (carbon monoxide + pentane)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McElroy, P.J.; Buchanan, S.</p> <p>1995-03-01</p> <p>Carbon monoxide and pentane are minor components of natural gas. The <span class="hlt">excess</span> second virial coefficient of the mixture carbon monoxide + pentane has been determined at 299.5, 313.15, 328.15, and 343.15 K using the <span class="hlt">pressure</span> change on mixing method. Unlike interaction second virial coefficients were derived and compared with the predictions of the Tsonopoulos correlation. The <span class="hlt">excess</span> enthalpy of mixing was also estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016WRR....52.5433P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016WRR....52.5433P"><span>Multiscale <span class="hlt">pore</span>-network representation of heterogeneous carbonate rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pak, Tannaz; Butler, Ian B.; Geiger, Sebastian; van Dijke, Marinus I. J.; Jiang, Zeyun; Surmas, Rodrigo</p> <p>2016-07-01</p> <p>A multiscale network integration approach introduced by Jiang et al. (2013) is used to generate a representative <span class="hlt">pore</span>-network for a carbonate rock with a <span class="hlt">pore</span> size distribution across several orders of magnitude. We predict the macroscopic flow parameters of the rock utilising (i) 3-D images captured by X-ray computed microtomography and (ii) <span class="hlt">pore</span>-network flow simulations. To capture the multiscale <span class="hlt">pore</span> size distribution of the rock, we imaged four different rock samples at different resolutions and integrated the data to produce a <span class="hlt">pore</span>-network model that combines information at several length-scales that cannot be recovered from a single tomographic image. A workflow for selection of the number and length-scale of the required input networks for the network integration process, as well as fine tuning the model parameters is presented. Mercury injection capillary-<span class="hlt">pressure</span> data were used to evaluate independently the multiscale networks. We explore single-scale, two-scale, and three-scale network models and discuss their representativeness by comparing simulated capillary-<span class="hlt">pressure</span> versus saturation curves with laboratory measurements. We demonstrate that for carbonate rocks with wide <span class="hlt">pore</span> size distributions, it may be required to integrate networks extracted from two or three discrete tomographic data sets in order to simulate macroscopic flow parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/889373','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/889373"><span>A <span class="hlt">pore</span> network model for adsorption in porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Satik, Cengiz; Yortsos, Yanis C.</p> <p>1995-01-26</p> <p>Using a <span class="hlt">pore</span> network model to represent porous media we investigate adsorption-desorption processes over the entire range of the relative <span class="hlt">pressure</span>, highlighting in particular capillary condensation. The model incorporates recent advances from density functional theory for adsorption-desorption in narrow <span class="hlt">pores</span> (of order as low as 1 nm), which improve upon the traditional multi-layer adsorption and Kelvin's equation for phase change and provide for the dependence of the critical <span class="hlt">pore</span> size on temperature. The limited accessibility of the <span class="hlt">pore</span> network gives rise to hysteresis in the adsorption-desorption cycle. This is due to the blocking of larger <span class="hlt">pores</span>, where adsorbed liquid is allowed to but cannot desorb, by smaller <span class="hlt">pores</span> containing liquid that may not desorb. By allowing for the existence of supercritical liquid in <span class="hlt">pores</span> in the nm range, it is found that the hysteresis area increases with an increase in temperature, in agreement with experiments of water adsorption-desorption in rock samples from The Geysers. It is also found that the hysteresis increases if the porous medium is represented as a fractured (dual porosity) system. The paper finds applications to general adsorption-desorption problems but it is illustrated here for geothermal applications in The Geysers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/63016','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/63016"><span>The effective <span class="hlt">pore</span> radius of screen wicks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Imura, Hideaki; Kozai, Hiroaki; Ikeda, Yuji</p> <p>1994-10-01</p> <p>The effective <span class="hlt">pore</span> radius in screen-wick heat pipes was investigated, which is very important for the prediction of maximum heat transfer rates due to capillary limitation. An equation for the effective <span class="hlt">pore</span> radius of the screen wicks was derived based on the model of the screen geometry. The capillary height for stainless steel and phosphor bronze screens was measured using water, ethyl alcohol, and Freon 113 as the test liquids. The effect of surface treatment (acid cleaning and oxidation) on the capillary height was also examined. From the comparison of the experimental data for water and ethyl alcohol with those for Freon 113, it was indicated that the contact angle was 24.2{degree} for water and 16.9{degree} for ethyl alcohol. Consequently, it was found that the effective <span class="hlt">pore</span> radius of the screen wicks could be predicted fairly well from the expression presented in this study, and that the contact angle should be taken into consideration to evaluate the maximum capillary <span class="hlt">pressure</span> accurately.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032763','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032763"><span>Numerical Simulation on Hydromechanical Coupling in Porous Media Adopting Three-Dimensional <span class="hlt">Pore</span>-Scale Model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Jianjun; Song, Rui; Cui, Mengmeng</p> <p>2014-01-01</p> <p>A novel approach of simulating hydromechanical coupling in <span class="hlt">pore</span>-scale models of porous media is presented in this paper. Parameters of the sandstone samples, such as the stress-strain curve, Poisson's ratio, and permeability under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span>, are tested in laboratory scale. The micro-CT scanner is employed to scan the samples for three-dimensional images, as input to construct the model. Accordingly, four physical models possessing the same <span class="hlt">pore</span> and rock matrix characteristics as the natural sandstones are developed. Based on the micro-CT images, the three-dimensional finite element models of both rock matrix and <span class="hlt">pore</span> space are established by MIMICS and ICEM software platform. Navier-Stokes equation and elastic constitutive equation are used as the mathematical model for simulation. A hydromechanical coupling analysis in <span class="hlt">pore</span>-scale finite element model of porous media is simulated by ANSYS and CFX software. Hereby, permeability of sandstone samples under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> has been predicted. The simulation results agree well with the benchmark data. Through reproducing its stress state underground, the prediction accuracy of the porous rock permeability in <span class="hlt">pore</span>-scale simulation is promoted. Consequently, the effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> on permeability are revealed from the microscopic view. PMID:24955384</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24955384','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24955384"><span>Numerical simulation on hydromechanical coupling in porous media adopting three-dimensional <span class="hlt">pore</span>-scale model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jianjun; Song, Rui; Cui, Mengmeng</p> <p>2014-01-01</p> <p>A novel approach of simulating hydromechanical coupling in <span class="hlt">pore</span>-scale models of porous media is presented in this paper. Parameters of the sandstone samples, such as the stress-strain curve, Poisson's ratio, and permeability under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span>, are tested in laboratory scale. The micro-CT scanner is employed to scan the samples for three-dimensional images, as input to construct the model. Accordingly, four physical models possessing the same <span class="hlt">pore</span> and rock matrix characteristics as the natural sandstones are developed. Based on the micro-CT images, the three-dimensional finite element models of both rock matrix and <span class="hlt">pore</span> space are established by MIMICS and ICEM software platform. Navier-Stokes equation and elastic constitutive equation are used as the mathematical model for simulation. A hydromechanical coupling analysis in <span class="hlt">pore</span>-scale finite element model of porous media is simulated by ANSYS and CFX software. Hereby, permeability of sandstone samples under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> has been predicted. The simulation results agree well with the benchmark data. Through reproducing its stress state underground, the prediction accuracy of the porous rock permeability in <span class="hlt">pore</span>-scale simulation is promoted. Consequently, the effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> on permeability are revealed from the microscopic view.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4642512','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4642512"><span>Micro/Nano-<span class="hlt">pore</span> Network Analysis of Gas Flow in Shale Matrix</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan</p> <p>2015-01-01</p> <p>The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale <span class="hlt">pore</span> may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale <span class="hlt">pore</span> network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed <span class="hlt">pore</span> network model accounts for the various size distributions and low connectivity of shale <span class="hlt">pores</span>. The <span class="hlt">pore</span> size, <span class="hlt">pore</span> throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted <span class="hlt">pore</span> network backbone. The numerical results show that apparent permeability is strongly dependent on <span class="hlt">pore</span> <span class="hlt">pressure</span> in the reservoir and <span class="hlt">pore</span> throat size, which is overestimated by low-<span class="hlt">pressure</span> laboratory tests. With the decrease of reservoir <span class="hlt">pressure</span>, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-<span class="hlt">pore</span> network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26310236','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26310236"><span>Micro/Nano-<span class="hlt">pore</span> Network Analysis of Gas Flow in Shale Matrix.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan</p> <p>2015-08-27</p> <p>The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale <span class="hlt">pore</span> may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale <span class="hlt">pore</span> network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed <span class="hlt">pore</span> network model accounts for the various size distributions and low connectivity of shale <span class="hlt">pores</span>. The <span class="hlt">pore</span> size, <span class="hlt">pore</span> throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted <span class="hlt">pore</span> network backbone. The numerical results show that apparent permeability is strongly dependent on <span class="hlt">pore</span> <span class="hlt">pressure</span> in the reservoir and <span class="hlt">pore</span> throat size, which is overestimated by low-<span class="hlt">pressure</span> laboratory tests. With the decrease of reservoir <span class="hlt">pressure</span>, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-<span class="hlt">pore</span> network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/840448','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/840448"><span>Nanoscale <span class="hlt">Pore</span> Imaging and <span class="hlt">Pore</span> Scale Fluid Flow Modeling in Chalk</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tomutsa, Liviu; Silin, Dmitriy</p> <p>2004-08-19</p> <p>For many rocks of high economic interest such as chalk, diatomite, tight gas sands or coal, nanometer scale resolution is needed to resolve the 3D-<span class="hlt">pore</span> structure, which controls the flow and trapping of fluids in the rocks. Such resolutions cannot be achieved with existing tomographic technologies. A new 3D imaging method, based on serial sectioning and using the Focused Ion Beam (FIB) technology has been developed. FIB allows for the milling of layers as thin as 10 nanometers by using accelerated Ga+ ions to sputter atoms from the sample surface. After each milling step, as a new surface is exposed, a 2D image of this surface is generated. Next, the 2D images are stacked to reconstruct the 3D <span class="hlt">pore</span> or grain structure. Resolutions as high as 10 nm are achievable using such a technique. A new robust method of <span class="hlt">pore</span>-scale fluid flow modeling has been developed and applied to sandstone and chalk samples. The method uses direct morphological analysis of the <span class="hlt">pore</span> space to characterize the petrophysical properties of diverse formations. Not only petrophysical properties (porosity, permeability, relative permeability and capillary <span class="hlt">pressures</span>) can be computed but also flow processes, such as those encountered in various IOR approaches, can be simulated. Petrophysical properties computed with the new method using the new FIB data will be presented. Present study is a part of the development of an Electronic Core Laboratory at LBNL/UCB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFD.L3006A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFD.L3006A"><span>Computational modeling of electrokinetic transport in random networks of micro-<span class="hlt">pores</span> and nano-<span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alizadeh, Shima; Mani, Ali</p> <p>2014-11-01</p> <p>A reduced order model has been developed to study the nonlinear electrokinetic behaviors emerging in the transport of ionic species through micro-scale and nano-scale porous media. In this approach a porous structure is modeled as a network of long and thin <span class="hlt">pores</span>. By assuming transport equilibrium in the thin dimensions for each <span class="hlt">pore</span>, a 1D transport equation is developed in the longitudinal direction covering a wide range of conditions including extreme limits of thick and thin electric double layers. This 1D model includes transport via diffusion, electromigration and wide range of advection mechanisms including <span class="hlt">pressure</span> driven flow, electroosmosis, and diffusion osmosis. The area-averaged equations governing the axial transport from different <span class="hlt">pores</span> are coupled at the <span class="hlt">pore</span> intersections using the proper conservation laws. Moreover, an asymptotic treatment has been included in order to remove singularities in the limit of small concentration. The proposed method provides an efficient framework for insightful simulations of porous electrokinetic systems with applications in water desalination and energy storage. PhD student in Mechanical Engineering, Stanford University. She received her Master's degree in Mechanical Engineering from Stanford at 2013. Her research interests include CFD, high performance computing, and optimization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/871686','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/871686"><span>Triggered <span class="hlt">pore</span>-forming agents</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bayley, Hagan; Walker, Barbara J.; Chang, Chung-yu; Niblack, Brett; Panchal, Rekha</p> <p>1998-01-01</p> <p>An inactive <span class="hlt">pore</span>-forming agent which is activated to lytic function by a condition such as pH, light, heat, reducing potential, or metal ion concentration, or substance such as a protease, at the surface of a cell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459163','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459163"><span><span class="hlt">Pore</span>-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.</p> <p>2017-01-01</p> <p>Extremely low permeability due to nano-scale <span class="hlt">pores</span> is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on <span class="hlt">pore</span> <span class="hlt">pressure</span>, porosity, <span class="hlt">pore</span> throat size and gas type. The <span class="hlt">pore</span> network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional <span class="hlt">pore</span> network model that includes typical bimodal <span class="hlt">pore</span> size distribution, anisotropy and low connectivity of the <span class="hlt">pore</span> structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir <span class="hlt">pressures</span> corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas <span class="hlt">pressure</span>, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir <span class="hlt">pressures</span> of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as <span class="hlt">pore</span> throat size and porosity. Finally, the impact of connectivity of nano-scale <span class="hlt">pores</span> on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix. PMID:28772465</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28772465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28772465"><span><span class="hlt">Pore</span>-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N</p> <p>2017-01-25</p> <p>Extremely low permeability due to nano-scale <span class="hlt">pores</span> is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on <span class="hlt">pore</span> <span class="hlt">pressure</span>, porosity, <span class="hlt">pore</span> throat size and gas type. The <span class="hlt">pore</span> network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional <span class="hlt">pore</span> network model that includes typical bimodal <span class="hlt">pore</span> size distribution, anisotropy and low connectivity of the <span class="hlt">pore</span> structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir <span class="hlt">pressures</span> corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas <span class="hlt">pressure</span>, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir <span class="hlt">pressures</span> of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as <span class="hlt">pore</span> throat size and porosity. Finally, the impact of connectivity of nano-scale <span class="hlt">pores</span> on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1060646','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1060646"><span>CO<sub>2</sub> Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by <span class="hlt">Excess</span> Sorption and Neutron Diffraction Measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rother, Gernot; Ilton, Eugene S.; Wallacher, Dirk; Hauβ, Thomas; Schaef, Herbert T.; Qafoku, Odeta; Rosso, Kevin M.; Felmy, Andrew R.; Krukowski, Elizabeth G.; Stack, Andrew G.; Grimm, Nico; Bodnar, Robert J.</p> <p>2013-01-02</p> <p>Geologic storage of CO<sub>2</sub> requires that the caprock sealing the storage rock is highly impermeable to CO<sub>2</sub>. Swelling clays, which are important components of caprocks, may interact with CO<sub>2</sub> leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO<sub>2</sub> with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The <span class="hlt">excess</span> sorption isotherms show maxima at bulk CO2 densities of ≈0.15 g/cm<sup>3</sup>, followed by an approximately linear decrease of <span class="hlt">excess</span> sorption to zero and negative values with increasing CO<sub>2</sub> bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO<sub>2</sub> are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO<sub>2</sub> in the clay <span class="hlt">pores</span> is relatively stable over a wide range of CO<sub>2</sub> <span class="hlt">pressures</span> at a given temperature, indicating the formation of a clay-CO<sub>2</sub> phase. Finally, at the <span class="hlt">excess</span> sorption maximum, increasing CO<sub>2</sub> sorption with decreasing temperature is observed while the high-<span class="hlt">pressure</span> sorption properties exhibit weak temperature dependence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22917276','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22917276"><span>CO2 sorption to subsingle hydration layer montmorillonite clay studied by <span class="hlt">excess</span> sorption and neutron diffraction measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rother, Gernot; Ilton, Eugene S; Wallacher, Dirk; Hauβ, Thomas; Schaef, Herbert T; Qafoku, Odeta; Rosso, Kevin M; Felmy, Andrew R; Krukowski, Elizabeth G; Stack, Andrew G; Grimm, Nico; Bodnar, Robert J</p> <p>2013-01-02</p> <p>Geologic storage of CO(2) requires that the caprock sealing the storage rock is highly impermeable to CO(2). Swelling clays, which are important components of caprocks, may interact with CO(2) leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO(2) with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The <span class="hlt">excess</span> sorption isotherms show maxima at bulk CO(2) densities of ≈ 0.15 g/cm(3), followed by an approximately linear decrease of <span class="hlt">excess</span> sorption to zero and negative values with increasing CO(2) bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO(2) are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO(2) in the clay <span class="hlt">pores</span> is relatively stable over a wide range of CO(2) <span class="hlt">pressures</span> at a given temperature, indicating the formation of a clay-CO(2) phase. At the <span class="hlt">excess</span> sorption maximum, increasing CO(2) sorption with decreasing temperature is observed while the high-<span class="hlt">pressure</span> sorption properties exhibit weak temperature dependence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16863218','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16863218"><span>Improvement of the Kruk-Jaroniec-Sayari method for <span class="hlt">pore</span> size analysis of ordered silicas with cylindrical mesopores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaroniec, Mietek; Solovyov, Leonid A</p> <p>2006-08-01</p> <p>In this work, the X-ray diffraction structure modeling was employed for analysis of hexagonally ordered large-<span class="hlt">pore</span> silicas, SBA-15, to determine their <span class="hlt">pore</span> width independently of adsorption measurements. Nitrogen adsorption isotherms were used to evaluate the relative <span class="hlt">pressure</span> of capillary condensation in cylindrical mesopores of these materials. This approach allowed us to extend the original Kruk-Jaroniec-Sayari (KJS) relation (Langmuir 1997, 13, 6267) between the <span class="hlt">pore</span> width and capillary condensation <span class="hlt">pressure</span> up to 10 nm instead of previously established range from 2 to 6.5 nm for a series of MCM-41 and to improve the KJS <span class="hlt">pore</span> size analysis of large <span class="hlt">pore</span> silicas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGE....12..587L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGE....12..587L"><span>Diagenetic facies controls on <span class="hlt">pore</span> structure and rock electrical parameters in tight gas sandstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Hongping; Zhao, Yanchao; Luo, Yang; Chen, Zhaoyou; He, Sheng</p> <p>2015-08-01</p> <p>Rock electrical parameters of tight gas sandstone show large variations in the T2 member in Dingbei Block, Ordos Basin, China. Applying the same rock electrical parameters in water saturation calculations would lead to large errors. Based on casting thin sections, x-ray diffraction, scanning electron microscopy (SEM), cathode luminescence, porosity and permeability, image analysis, and high-<span class="hlt">pressure</span> mercury intrusion/withdrawal method, identification of the diagenetic facies are first conducted, and then their <span class="hlt">pore</span> structure and their relationship with rock electrical parameters are investigated. Five diagenetic facies (A-E), which are identified based mainly on <span class="hlt">pore</span> types and authigenic minerals, have different <span class="hlt">pore</span> structure and rock electrical parameters. Conceptual models that incorporate the rock properties of each diagenetic facies have been built, before applying the electrical efficiency theory to explain the values of cementation exponent (m) and saturation exponent (n). A conventional network model, a shunt <span class="hlt">pore</span> model, a netted <span class="hlt">pore</span> model, and a dotted line model are utilized to mimic the intergranular <span class="hlt">pores</span>, authigenic kaolinite intercrystal <span class="hlt">pores</span>, carbonate-cement dissolution <span class="hlt">pores</span>, and clay-matrix intercrystal <span class="hlt">pores</span>, respectively. A decrease of the contents of large <span class="hlt">pores</span> increases electrical efficiency and therefore reduces m. The saturation exponent, which depends on the distribution of water and gas, can be better understood by applying the different <span class="hlt">pore</span> models. In the shunt and netted <span class="hlt">pore</span> models, gas displacement starts from the larger <span class="hlt">pores</span> and smaller <span class="hlt">pores</span> provide alternative conduction pathways, hence sustaining electrical efficiency and decreasing n. Clay-matrix intercrystal <span class="hlt">pores</span> are mainly micropores, since the brine in the rocks are isolated after gas displacement, reducing overall electrical efficiency and dramatically increasing the value of n in the diagenetic facies, which is dominated by clay-matrix intercrystal <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70185448','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70185448"><span>Measurement of variation in soil solute tracer concentration across a range of effective <span class="hlt">pore</span> sizes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Harvey, Judson W.</p> <p>1993-01-01</p> <p>Solute transport concepts in soil are based on speculation that solutes are distributed nonuniformly within large and small <span class="hlt">pores</span>. Solute concentrations have not previously been measured across a range of <span class="hlt">pore</span> sizes and examined in relation to soil hydrological properties. For this study, modified <span class="hlt">pressure</span> cells were used to measure variation in concentration of a solute tracer across a range of <span class="hlt">pore</span> sizes. Intact cores were removed from the site of a field tracer experiment, and soil water was eluted from 10 or more discrete classes of <span class="hlt">pore</span> size. Simultaneous changes in water content and unsaturated hydraulic conductivity were determined on cores using standard <span class="hlt">pressure</span> cell techniques. Bromide tracer concentration varied by as much as 100% across the range of <span class="hlt">pore</span> sizes sampled. Immediately following application of the bromide tracer on field plots, bromide was most concentrated in the largest <span class="hlt">pores</span>; concentrations were lower in <span class="hlt">pores</span> of progressively smaller sizes. After 27 days, bromide was most dilute in the largest <span class="hlt">pores</span> and concentrations were higher in the smaller <span class="hlt">pores</span>. A sharp, threefold decrease in specific water capacity during elution indicated separation of two major <span class="hlt">pore</span> size classes at a <span class="hlt">pressure</span> of 47 cm H2O and a corresponding effective <span class="hlt">pore</span> diameter of 70 μm. Variation in tracer concentration, on the other hand, was spread across the entire range of <span class="hlt">pore</span> sizes investigated in this study. A two-porosity characterization of the transport domain, based on water retention criteria, only broadly characterized the pattern of variation in tracer concentration across <span class="hlt">pore</span> size classes during transport through a macroporous soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2294438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2294438"><span><span class="hlt">Excess</span> mortality in Harlem.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCord, C; Freeman, H P</p> <p>1990-01-18</p> <p>In recent decades mortality rates have declined for both white and nonwhite Americans, but national averages obscure the extremely high mortality rates in many inner-city communities. Using data from the 1980 census and from death certificates in 1979, 1980, and 1981, we examined mortality rates in New York City's Central Harlem health district, where 96 percent of the inhabitants are black and 41 percent live below the poverty line. For Harlem, the age-adjusted rate of mortality from all causes was the highest in New York City, more than double that of U.S. whites and 50 percent higher than that of U.S. blacks. Almost all the <span class="hlt">excess</span> mortality was among those less than 65 years old. With rates for the white population as the basis for comparison, the standardized (adjusted for age) mortality ratios (SMRs) for deaths under the age of 65 in Harlem were 2.91 for male residents and 2.70 for female residents. The highest ratios were for women 25 to 34 years old (SMR, 6.13) and men 35 to 44 years old (SMR, 5.98). The chief causes of this <span class="hlt">excess</span> mortality were cardiovascular disease (23.5 percent of the <span class="hlt">excess</span> deaths; SMR, 2.23), cirrhosis (17.9 percent; SMR, 10.5), homicide (14.9 percent; SMR, 14.2), and neoplasms (12.6 percent; SMR, 1.77). Survival analysis showed that black men in Harlem were less likely to reach the age of 65 than men in Bangladesh. Of the 353 health areas in New York, 54 (with a total population of 650,000) had mortality rates for persons under 65 years old that were at lest twice the expected rate. All but one of these areas of high mortality were predominantly black or Hispanic. We conclude that Harlem and probably other inner-city areas with largely black populations have extremely high mortality rates that justify special consideration analogous to that given to natural-disaster areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H21A1320H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H21A1320H"><span><span class="hlt">Pore</span>-scale Modelling of Capillarity in Swelling Granular Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hassanizadeh, S. M.; Sweijen, T.; Nikooee, E.; Chareyre, B.</p> <p>2015-12-01</p> <p>Capillarity in granular porous media is a common and important phenomenon in earth materials and industrial products, and therefore has been studied extensively. To model capillarity in granular porous media, one needs to go beyond current models which simulate either two-phase flow in porous media or mechanical behaviour in granular media. Current <span class="hlt">pore</span>-scale models for two-phase flow such as <span class="hlt">pore</span>-network models are tailored for rigid <span class="hlt">pore</span>-skeletons, even though in many applications, namely hydro-mechanical coupling in soils, printing, and hygienic products, the porous structure does change during two-phase flow. On the other hand, models such as Discrete Element Method (DEM), which simulate the deformable porous media, have mostly been employed for dry or saturated granular media. Here, the effects of porosity change and swelling on the retention properties was studied, for swelling granular materials. A <span class="hlt">pore</span>-unit model that was capable to construct the capillary <span class="hlt">pressure</span> - saturation curve was coupled to DEM. Such that the capillary <span class="hlt">pressure</span> - saturation curve could be constructed for varying porosities and amounts of absorbed water. The study material was super absorbent polymer particles, which are capable to absorb water 10's to 200 times their initial weight. We have simulated quasi-static primary imbibition for different porosities and amounts of absorbed water. The results reveal a 3 dimensional surface between capillary <span class="hlt">pressure</span>, saturation, and porosity, which can be normalized by means of the entry <span class="hlt">pressure</span> and the effective water saturation to a unique curve.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3976240','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3976240"><span>Consequences of <span class="hlt">excess</span> iodine</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Leung, Angela M.; Braverman, Lewis E.</p> <p>2014-01-01</p> <p>Iodine is a micronutrient that is essential for the production of thyroid hormones. The primary source of iodine is the diet via consumption of foods that have been fortified with iodine, including salt, dairy products and bread, or that are naturally abundant in the micronutrient, such as seafood. Recommended daily iodine intake is 150 μg in adults who are not pregnant or lactating. Ingestion of iodine or exposure above this threshold is generally well-tolerated. However, in certain susceptible individuals, including those with pre-existing thyroid disease, the elderly, fetuses and neonates, or patients with other risk factors, the risk of developing iodine-induced thyroid dysfunction might be increased. Hypothyroidism or hyperthyroidism as a result of supraphysiologic iodine exposure might be either subclinical or overt, and the source of the <span class="hlt">excess</span> iodine might not be readily apparent. PMID:24342882</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028632','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028632"><span>Methods for <span class="hlt">pore</span> water extraction from unsaturated zone tuff, Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Scofield, K.M.</p> <p>2006-01-01</p> <p>Assessing the performance of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, requires an understanding of the chemistry of the water that moves through the host rock. The uniaxial compression method used to extract <span class="hlt">pore</span> water from samples of tuffaceous borehole core was successful only for nonwelded tuff. An ultracentrifugation method was adopted to extract <span class="hlt">pore</span> water from samples of the densely welded tuff of the proposed repository horizon. Tests were performed using both methods to determine the efficiency of <span class="hlt">pore</span> water extraction and the potential effects on <span class="hlt">pore</span> water chemistry. Test results indicate that uniaxial compression is most efficient for extracting <span class="hlt">pore</span> water from nonwelded tuff, while ultracentrifugation is more successful in extracting <span class="hlt">pore</span> water from densely welded tuff. <span class="hlt">Pore</span> water splits collected from a single nonwelded tuff core during uniaxial compression tests have shown changes in <span class="hlt">pore</span> water chemistry with increasing <span class="hlt">pressure</span> for calcium, chloride, sulfate, and nitrate. <span class="hlt">Pore</span> water samples collected from the intermediate <span class="hlt">pressure</span> ranges should prevent the influence of re-dissolved, evaporative salts and the addition of ion-deficient water from clays and zeolites. Chemistry of <span class="hlt">pore</span> water splits from welded and nonwelded tuffs using ultracentrifugation indicates that there is no substantial fractionation of solutes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1059710','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1059710"><span>CO2 Adsorption to Sub-Single Hydration Layer Montmorillonite Clay Studied by <span class="hlt">Excess</span> Sorption and Neutron Diffraction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rother, Gernot; Ilton, Eugene; Wallacher, Dirk; Hauss, Thomas; Schaef, Herbert; Qafoku, Odeta; Rosso, Kevin M.; Felmy, Andrew; Krukowski, Elizabeth G; Stack, Andrew G; Bodnar, Robert J</p> <p>2013-01-01</p> <p>Geologic storage of CO2 requires that the caprock sealing the storage rock is highly impermeable by CO2. Swelling clays, which are important components of caprocks, may react with CO2 under volume change, potentially impacting the seal quality. The interactions of scCO2 with Na saturated montmorillonite clay containing a sub-single layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The <span class="hlt">excess</span> sorption isotherms show maxima at bulk CO2 densities of 0.15 g/cm3, followed by an approximately linear decrease of <span class="hlt">excess</span> sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 . The density of CO2 in the clay <span class="hlt">pores</span> is relatively stable over a wide range of CO2 <span class="hlt">pressures</span> at a given temperature, indicating the formation of a clay-CO2 phase. At low <span class="hlt">pressure</span> increasing CO2 adsorption with decreasing temperature is observed while the high-<span class="hlt">pressure</span> sorption properties exhibit weak or no temperature dependence. Supercritical fluids, sorption phenomena, carbon dioxide, carbon sequestration, caprock integrity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T21C2585H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T21C2585H"><span>Effects of fluid <span class="hlt">pressures</span> to the seismic velocity of crustal rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harada, Y.; Katayama, I.</p> <p>2012-12-01</p> <p>Introduction Water of the earth interior is mainly supplied at the subduction zone and has important role on seismic activity and volcanism in island arc. It is suggested that slow slip events and tremors occurring at this region are related to water (e.g., Obara, 2000). Based on the seismic tomography beneath Kanto district, high Poisson's ratio area (~0.337) was observed and suggested weak seismic coupling at plate interface (Kamiya and Kobayashi, 2000). Similar high Poisson's ratio is detected beneath Tonankai and Shikoku district, exceeding 0.3. Those regions correspond to the plate boundary generating slow slip events or tremors (Kodaira et al., 2004 ; Shelly et al., 2006). Because relatively young oceanic plates are subducting in districts from Kanto to Sikoku, antigorite which Poisson's ratio is ~0.29 may exist stably in those areas. In this case, the observed high Poisson's ratio requires <span class="hlt">excess</span> <span class="hlt">pore</span> fluids in addition to the serpentinized mantle. In order to clarify geometry and the abundance of water, we investigate seismic velocity of crustal rocks under high confining <span class="hlt">pressure</span> and <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>. Experimental methods For the measurement of seismic velocity, we used the hydraulic <span class="hlt">pressure</span> vessel in Hiroshima University, in which seismic velocity was calculated by using pulse echo method. We used the Aji granite as a test sample, which was prepared into a cylindrical shape with 20 mm diameter and 5-10 mm length. The top and bottom of sample were polished mirror surfaces within 0.001 mm difference. We measured seismic velocity under dry and wet conditions. In the later case, distilled water is supplied into the sample with <span class="hlt">pore</span> <span class="hlt">pressure</span> up to 100 MPa, and we also measured permeable time of water at Pc = 20 MPa, Pp = 0 MPa and Pc =40 MPa, Pp =20 MPa. Results and discussion Under dry experiments, seismic velocities of granite were measured up to confining <span class="hlt">pressure</span> as high as 200 MPa. Calculated velocities were Vp = 5.900 km/s, Vs = 3.478 km/s at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6217710','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6217710"><span>Geostatistical Modeling of <span class="hlt">Pore</span> Velocity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Devary, J.L.; Doctor, P.G.</p> <p>1981-06-01</p> <p>A significant part of evaluating a geologic formation as a nuclear waste repository involves the modeling of contaminant transport in the surrounding media in the event the repository is breached. The commonly used contaminant transport models are deterministic. However, the spatial variability of hydrologic field parameters introduces uncertainties into contaminant transport predictions. This paper discusses the application of geostatistical techniques to the modeling of spatially varying hydrologic field parameters required as input to contaminant transport analyses. Kriging estimation techniques were applied to Hanford Reservation field data to calculate hydraulic conductivity and the ground-water potential gradients. These quantities were statistically combined to estimate the groundwater <span class="hlt">pore</span> velocity and to characterize the <span class="hlt">pore</span> velocity estimation error. Combining geostatistical modeling techniques with product error propagation techniques results in an effective stochastic characterization of groundwater <span class="hlt">pore</span> velocity, a hydrologic parameter required for contaminant transport analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1265817','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1265817"><span>Estimation and modeling of coal <span class="hlt">pore</span> accessibility using small angle neutron scattering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Rui; Liu, Shimin; Bahadur, Jitendra; Elsworth, Derek; Melnichenko, Yuri; He, Lilin; Wang, Yi</p> <p>2015-09-04</p> <p>Gas diffusion in coal is controlled by nano-structure of the <span class="hlt">pores</span>. The interconnectivity of <span class="hlt">pores</span> not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify <span class="hlt">pore</span> accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical <span class="hlt">pore</span> accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas <span class="hlt">pressure</span> using deuterated methane (CD<sub>4</sub>) at low Q values for both coals. <span class="hlt">Pores</span> smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous co