Science.gov

Sample records for air filled porosity

  1. On the air-filled effective porosity parameter of Rogers and Nielson's (1991) bulk radon diffusion coefficient in unsaturated soils.

    PubMed

    Saâdi, Zakaria

    2014-05-01

    The radon exhalation rate at the earth's surface from soil or rock with radium as its source is the main mechanism behind the radon activity concentrations observed in both indoor and outdoor environments. During the last two decades, many subsurface radon transport models have used Rogers and Nielson's formula for modeling the unsaturated soil bulk radon diffusion coefficient. This formula uses an "air-filled effective porosity" to account for radon adsorption and radon dissolution in the groundwater. This formula is reviewed here, and its hypotheses are examined for accuracy in dealing with subsurface radon transport problems. The author shows its limitations by comparing one dimensional steady-state analytical solutions of the two-phase (air/water) transport equation (Fick's law) with Rogers and Nielson's formula. For radon diffusion-dominated transport, the calculated Rogers and Nielson's radon exhalation rate is shown to be unrealistic as it is independent of the values of the radon adsorption and groundwater dissolution coefficients. For convective and diffusive transport, radon exhalation rates calculated using Fick's law and this formula agree only for high values of gas-phase velocity and groundwater saturation. However, these conditions are not usually met in most shallow subsurface environments where radon migration takes place under low gas phase velocities and low water saturation.

  2. The Relationship Between Soil Air Filled Porosity and Soil Methane Oxidation is Almost Identical in Both Dry and Wet Temperate Eucalypt Forests

    NASA Astrophysics Data System (ADS)

    Fest, B. J.; Wardlaw, T.; Hinko-Najera, N.; Arndt, S. K.

    2015-12-01

    In order to gain a better understanding of the temporal variation in soil methane (CH4) exchange in temperate evergreen eucalypt forests in south-eastern Australia we measured soil CH4 exchange in high temporal resolution (every 2 hours or less) over two consecutive years (Wombat State Forest, Victoria, AUS) and over one year (Warra, Tasmania, AUS) in two temperate Eucalyptus obliqua (L. Her) forests with contrasting annual precipitation (Wombat State Forest = 870 mm yr-1, Warra = 1700 mm yr-1). Both forests were continuous CH4 sinks with the Victorian site having a sink strength of -1.79 kg CH4 ha-1 yr-1 and the Tasmanian site having a sink strength of -3.83 kg CH4 ha-1 yr-1. Our results show that CH4 uptake was strongly controlled by soil moisture at both sites and explained up to 90% of the temporal variability in CH4 uptake. Furthermore, when soil moisture was expressed as soil air filled porosity (AFP) we were able to predict the CH4 uptake of one site by the linear regression between AFP and CH4 uptake from the other site. Soil temperature only had an apparent control over seasonal variation in CH4 uptake during periods when soil moisture and soil temperature were closely correlated. The fluctuation of the generally low soil nitrogen levels did not influence soil CH4 uptake at either site.

  3. Soil methane oxidation in both dry and wet temperate eucalypt forests shows a near-identical relationship with soil air-filled porosity

    NASA Astrophysics Data System (ADS)

    Fest, Benedikt J.; Hinko-Najera, Nina; Wardlaw, Tim; Griffith, David W. T.; Livesley, Stephen J.; Arndt, Stefan K.

    2017-01-01

    Well-drained, aerated soils are important sinks for atmospheric methane (CH4) via the process of CH4 oxidation by methane-oxidising bacteria (MOB). This terrestrial CH4 sink may contribute towards climate change mitigation, but the impact of changing soil moisture and temperature regimes on CH4 uptake is not well understood in all ecosystems. Soils in temperate forest ecosystems are the greatest terrestrial CH4 sink globally. Under predicted climate change scenarios, temperate eucalypt forests in south-eastern Australia are predicted to experience rapid and extreme changes in rainfall patterns, temperatures and wild fires. To investigate the influence of environmental drivers on seasonal and inter-annual variation of soil-atmosphere CH4 exchange, we measured soil-atmosphere CH4 exchange at high-temporal resolution (< 2 h) in a dry temperate eucalypt forest in Victoria (Wombat State Forest, precipitation 870 mm yr-1) and in a wet temperature eucalypt forest in Tasmania (Warra Long-Term Ecological Research site, 1700 mm yr-1). Both forest soil systems were continuous CH4 sinks of -1.79 kg CH4 ha-1 yr-1 in Victoria and -3.83 kg CH4 ha-1 yr-1 in Tasmania. Soil CH4 uptake showed substantial temporal variation and was strongly controlled by soil moisture at both forest sites. Soil CH4 uptake increased when soil moisture decreased and this relationship explained up to 90 % of the temporal variability. Furthermore, the relationship between soil moisture and soil CH4 flux was near-identical at both forest sites when soil moisture was expressed as soil air-filled porosity (AFP). Soil temperature only had a minor influence on soil CH4 uptake. Soil nitrogen concentrations were generally low and fluctuations in nitrogen availability did not influence soil CH4 uptake at either forest site. Our data suggest that soil MOB activity in the two forests was similar and that differences in soil CH4 exchange between the two forests were related to differences in soil moisture and

  4. [Comparative study of the seal and porosity of provisional coronal filling materials in endodontics].

    PubMed

    Scherman, L; Nebot, D

    1989-06-01

    The porosity and the leakage properties of 13 temporary fillings used between each appointment during endodontic treatment were investigated by means of thermocycling and dye staining of the interface between the teeth and the filling material. A scanning electron microscope was also used for these observations. The 8 commercially produced temporary fillings seal adequately the cavity whereas the 5 materials prepared and mixed by the practitioner allowed wide staining diffusion and therefore were leaky.

  5. Plastic Foam Porosity Characterization by Air-Borne Ultrasound

    NASA Astrophysics Data System (ADS)

    Hoffrén, H.; Karppinen, T.; Hæggström, E.

    2006-03-01

    We continue to develop an ultrasonic burst-reflection method for estimating porosity and tortuosity of solid materials. As a first step we report on method design considerations and measurements on polyurethane foams (Sylomer® vibration dampener) with well-defined porosity. The ultrasonic method is experimentally tested by measuring 235 kHz and 600 kHz air-borne ultrasound reflection from a foam surface at two incidence angles. The reflected sound wave from different foam samples (32% - 64% porosity) was compared to a wave that had traveled from the transmitter to the detector without reflection. The ultrasonically estimated sample porosities coincided within 8% with the porosity estimates obtained by a gravimetric reference method. This parallels the uncertainty of the gravimetric method, 8%. The repeatability of the ultrasonic porosity measurements was better than 5%.

  6. Polystyrene Foam Products Equation of State as a Function of Porosity and Fill Gas

    NASA Astrophysics Data System (ADS)

    Mulford, R. N.; Swift, D. C.

    2009-12-01

    An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO2-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O2-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO2 decomposes at high temperatures.

  7. Polystyrene foam products equation of state as a function of porosity and fill gas

    SciTech Connect

    Mulford, Roberta N; Swift, Damian C

    2009-01-01

    An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO{sub 2}-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O{sub 2}-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO{sub 2} decomposes at high temperatures.

  8. Fluid-filled porosity of magmatic underplates from joint inversion of P and S receiver functions

    NASA Astrophysics Data System (ADS)

    Vinnik, Lev; Oreshin, Sergey; Makeyeva, Larissa; Dündar, Süleyman

    2017-02-01

    Vp/Vs ratio where Vp and Vs are P- and S-wave velocities is an indicator of rock composition, but estimates of Vp/Vs for the lower continental crust remain sparse. We present estimates of Vs, Vp and Vp/Vs in the crust of the Archean-Paleoproterozoic Siberian craton that are obtained by simultaneous inversion of P and S receiver functions from GSN seismograph stations NRIL, YAK and TIXI. These stations are located in the region of the Siberian traps (NRIL), close to the Laptev Sea Rift (TIXI) and the Viluy rift system (YAK). The most conspicuous result of our analysis is a high Vp/Vs ratio ( \\ge 2.0) at depths from 20-30 km to 40 km. A very high Vp in this layer (from 7 to 8 km/s) is indicative of magmatic underplating. We find broadly similar data in the western Mediterranean and in India. In a dry lower crust the Vp/Vs ratio is ∼1.8, which is hard to reconcile with the estimates > 2.0. A coincidence in depths of zones of high electric conductivity and of anomalously high Vp/Vs in Siberia suggests that both may have the same origin: fluid-filled porosity. The porosity which is required by our seismic observations is on the order of 1%. Origins of the fluids may be linked with processes of magmatic underplating. Key words: Body waves, Crustal imaging, Composition and structure of the continental crust, Permeability and porosity, Large igneous provinces, Cratons.

  9. Polystyrene Foam EOS as a Function of Porosity and Fill Gas

    NASA Astrophysics Data System (ADS)

    Mulford, Roberta; Swift, Damian

    2009-06-01

    An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam, Differences between air-filled, nitrogen-blown, and CO2-blown foams are investigated, to estimate the importance of allowing air to react with plastic products during decomposition. Results differ somewhat from the conventional EOS, which are generated from values for plastic extrapolated to low densities.

  10. Numerical simulation of casting processes: coupled mould filling and solidification using VOF and enthalpy-porosity method

    NASA Astrophysics Data System (ADS)

    Richter, Ole; Turnow, Johann; Kornev, Nikolai; Hassel, Egon

    2016-12-01

    Within the scope of industrial casting applications a numerical model for the simultaneous mould filling and solidification process has been formulated, implemented in a finite volume code and successfully validated using analytical and experimental data. In order to account for the developing of free surface flow and the liquid/solid phase change, respectively, the volume-of-fluid and enthalpy-porosity method have been coupled under a volume averaging framework on a fixed Eulerian grid. The coupled method captures the basic physical effects of a combined mould filling and solidification process and provides a trustful method for comprehensive casting simulations.

  11. Apparatus and methods for determining gas saturation and porosity of a formation penetrated by a gas filled or liquid filled borehole

    DOEpatents

    Wilson, Robert D.

    2001-03-27

    Methods and apparatus are disclosed for determining gas saturation, liquid saturation, porosity and density of earth formations penetrated by a well borehole. Determinations are made from measures of fast neutron and inelastic scatter gamma radiation induced by a pulsed, fast neutron source. The system preferably uses two detectors axially spaced from the neutron source. One detector is preferably a scintillation detector responsive to gamma radiation, and a second detector is preferably an organic scintillator responsive to both neutron and gamma radiation. The system can be operated in cased boreholes which are filled with either gas or liquid. Techniques for correcting all measurements for borehole conditions are disclosed.

  12. Air flow paths and porosity/permeability change in a saturated zone during in situ air sparging.

    PubMed

    Tsai, Yih-Jin

    2007-04-02

    This study develops methods to estimate the change in soil characteristics and associated air flow paths in a saturated zone during in situ air sparging. These objectives were achieved by performing combined in situ air sparging and tracer testing, and comparing the breakthrough curves obtained from the tracer gas with those obtained by a numerical simulation model that incorporates a predicted change in porosity that is proportional to the air saturation. The results reveal that revising the porosity and permeability according to the distribution of gas saturation is helpful in breakthrough curve fitting, however, these changes are unable to account for the effects of preferential air flow paths, especially in the zone closest to the points of air injection. It is not known the extent to which these preferential air flow paths were already present versus created, increased, or reduced as a result of the air sparging experiment. The transport of particles from around the sparging well could account for the overall increase in porosity and permeability observed in the study. Collection of soil particles in a monitoring well within 2m of the sparging well provided further evidence of the transport of particles. Transport of particles from near the sparging well also appeared to decrease the radius of influence (ROI). Methods for predicting the effects of pressurized air injection and water flow on the creation or modification of preferential air flow paths are still needed to provide a full description of the change in soil conditions that accompany air sparging.

  13. Partitioned airs at microscale and nanoscale: thermal diffusivity in ultrahigh porosity solids of nanocellulose

    PubMed Central

    Sakai, Koh; Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2016-01-01

    High porosity solids, such as plastic foams and aerogels, are thermally insulating. Their insulation performance strongly depends on their pore structure, which dictates the heat transfer process in the material. Understanding such a relationship is essential to realizing highly efficient thermal insulators. Herein, we compare the heat transfer properties of foams and aerogels that have very high porosities (97.3–99.7%) and an identical composition (nanocellulose). The foams feature rather closed, microscale pores formed with a thin film-like solid phase, whereas the aerogels feature nanoscale open pores formed with a nanofibrous network-like solid skeleton. Unlike the aerogel samples, the thermal diffusivity of the foam decreases considerably with a slight increase in the solid fraction. The results indicate that for suppressing the thermal diffusion of air within high porosity solids, creating microscale spaces with distinct partitions is more effective than directly blocking the free path of air molecules at the nanoscale. PMID:26830144

  14. Partitioned airs at microscale and nanoscale: thermal diffusivity in ultrahigh porosity solids of nanocellulose

    NASA Astrophysics Data System (ADS)

    Sakai, Koh; Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2016-02-01

    High porosity solids, such as plastic foams and aerogels, are thermally insulating. Their insulation performance strongly depends on their pore structure, which dictates the heat transfer process in the material. Understanding such a relationship is essential to realizing highly efficient thermal insulators. Herein, we compare the heat transfer properties of foams and aerogels that have very high porosities (97.3–99.7%) and an identical composition (nanocellulose). The foams feature rather closed, microscale pores formed with a thin film-like solid phase, whereas the aerogels feature nanoscale open pores formed with a nanofibrous network-like solid skeleton. Unlike the aerogel samples, the thermal diffusivity of the foam decreases considerably with a slight increase in the solid fraction. The results indicate that for suppressing the thermal diffusion of air within high porosity solids, creating microscale spaces with distinct partitions is more effective than directly blocking the free path of air molecules at the nanoscale.

  15. Interaction of finite-amplitude sound with air-filled porous materials

    NASA Technical Reports Server (NTRS)

    Nelson, D. A.

    1985-01-01

    The propagation of high intensity sound waves through an air-filled porus material was studied. The material is assumed: (1) to be rigid, incompressible, and homogeneous, and (2) to be adequately described by two properties: resistivity r and porosity. The resulting wave equation is still nonlinear, however, because of the u sgn(u) term in the resistivity. The equation is solved in the frequency domain as an infinite set of coupled inhomogeneous Helmholtz equations, one for each harmonic. An approximate but analytical solution leads to predictions of excess attenuation, saturation, and phase speed reduction for the fundamental component. A more general numerical solution is used to calculate the propagation curves for the higher harmonics. The u sgn(u) nonlinearity produces a cubic distortion pattern; when the input signal is a pure tone, only odd harmonic distortion products are generated.

  16. Restoration of middle-ear input in fluid-filled middle ears by controlled introduction of air or a novel air-filled implant.

    PubMed

    Ravicz, Michael E; Chien, Wade W; Rosowski, John J

    2015-10-01

    The effect of small amounts of air on sound-induced umbo velocity in an otherwise saline-filled middle ear (ME) was investigated to examine the efficacy of a novel balloon-like air-filled ME implant suitable for patients with chronically non-aerated MEs. In this study, air bubbles or air-filled implants were introduced into saline-filled human cadaveric MEs. Umbo velocity, a convenient measure of ME response, served as an indicator of hearing sensitivity. Filling the ME with saline reduced umbo velocity by 25-30 dB at low frequencies and more at high frequencies, consistent with earlier work (Ravicz et al., Hear. Res. 195: 103-130 (2004)). Small amounts of air (∼30 μl) in the otherwise saline-filled ME increased umbo velocity substantially, to levels only 10-15 dB lower than in the dry ME, in a frequency- and location-dependent manner: air in contact with the tympanic membrane (TM) increased umbo velocity at all frequencies, while air located away from the TM increased umbo velocity only below about 500 Hz. The air-filled implant also affected umbo velocity in a manner similar to an air bubble of equivalent compliance. Inserting additional implants into the ME had the same effect as increasing air volume. These results suggest these middle-ear implants would significantly reduce conductive hearing loss in patients with chronically fluid-filled MEs.

  17. Using soft computing techniques to predict corrected air permeability using Thomeer parameters, air porosity and grain density

    NASA Astrophysics Data System (ADS)

    Nooruddin, Hasan A.; Anifowose, Fatai; Abdulraheem, Abdulazeez

    2014-03-01

    Soft computing techniques are recently becoming very popular in the oil industry. A number of computational intelligence-based predictive methods have been widely applied in the industry with high prediction capabilities. Some of the popular methods include feed-forward neural networks, radial basis function network, generalized regression neural network, functional networks, support vector regression and adaptive network fuzzy inference system. A comparative study among most popular soft computing techniques is presented using a large dataset published in literature describing multimodal pore systems in the Arab D formation. The inputs to the models are air porosity, grain density, and Thomeer parameters obtained using mercury injection capillary pressure profiles. Corrected air permeability is the target variable. Applying developed permeability models in recent reservoir characterization workflow ensures consistency between micro and macro scale information represented mainly by Thomeer parameters and absolute permeability. The dataset was divided into two parts with 80% of data used for training and 20% for testing. The target permeability variable was transformed to the logarithmic scale as a pre-processing step and to show better correlations with the input variables. Statistical and graphical analysis of the results including permeability cross-plots and detailed error measures were created. In general, the comparative study showed very close results among the developed models. The feed-forward neural network permeability model showed the lowest average relative error, average absolute relative error, standard deviations of error and root means squares making it the best model for such problems. Adaptive network fuzzy inference system also showed very good results.

  18. Mathematical model of an air-filled alpha stirling refrigerator

    NASA Astrophysics Data System (ADS)

    McFarlane, Patrick; Semperlotti, Fabio; Sen, Mihir

    2013-10-01

    This work develops a mathematical model for an alpha Stirling refrigerator with air as the working fluid and will be useful in optimizing the mechanical design of these machines. Two pistons cyclically compress and expand air while moving sinusoidally in separate chambers connected by a regenerator, thus creating a temperature difference across the system. A complete non-linear mathematical model of the machine, including air thermodynamics, and heat transfer from the walls, as well as heat transfer and fluid resistance in the regenerator, is developed. Non-dimensional groups are derived, and the mathematical model is numerically solved. The heat transfer and work are found for both chambers, and the coefficient of performance of each chamber is calculated. Important design parameters are varied and their effect on refrigerator performance determined. This sensitivity analysis, which shows what the significant parameters are, is a useful tool for the design of practical Stirling refrigeration systems.

  19. Response of air-filled ion chambers to high-intensity radiation pulses

    SciTech Connect

    Plum, M.; Brown, D.

    1993-06-01

    Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

  20. Response of air-filled ion chambers to high-intensity radiation pulses

    SciTech Connect

    Plum, M.; Brown, D.

    1993-01-01

    Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

  1. Porosity and sorption properties of activated carbons prepared from anthracite by steam-air activation

    SciTech Connect

    Sych, N.V.; Kartel, N.T.; Tsyba, N.N.; Strelko, V.V.; Nikolaichuk, A.D.; Mironyuk, T.I.

    2006-04-15

    Fundamental aspects of the steam-air activation of anthracite from Donets coal fields were studied. The effect of the flow rate of moistened air on the development of a porous structure and the sorption properties of the adsorbents obtained were examined.

  2. Inflation pressure effect on performance of air-filled wheelchair cushions.

    PubMed

    Krouskop, T A; Williams, R; Noble, P; Brown, J

    1986-02-01

    Air-filled wheelchair cushions are frequently used in the prevention of pressure sores. Their effectiveness in reducing interface pressures and in redistributing body weight (BW) appears dependent on their internal inflation pressure. This pilot study examines and defines this relationship. Interface pressures were measured with the TIPE (Texas Interface Pressure Evaluator) system for 14 subjects while sitting on each of three commercially available air-filled wheelchair cushions. This relationship between interface pressure and internal pressure was then determined for each of the three body-build categories. In each category the interface pressure displayed a higher degree of sensitivity to underinflation than to overinflation. A high correlation found between BW and internal air pressure (IAP), may be useful in the design of a customized pressure indicator system. The study documents the influence of IAP on seating pressure and supports the need for further research in the development of an indicator system that alerts users to under- or overinflation of the cushion.

  3. Porosity control in nanoporous carbide-derived carbon by oxidation in air and carbon dioxide

    SciTech Connect

    Osswald, S.; Portet, C.; Gogotsi, Y.; Laudisio, G.; Singer, J.P.; Fischer, J.E.; Sokolov, V.V.; Kukushkina, J.A.; Kravchik, A.E.

    2009-07-15

    Carbide-derived carbons (CDC) allow a precise control over the pore size through the selection of the carbide precursor and varying of the synthesis conditions. However, their pore volume is limited by the carbide stoichiometry. While activation of carbons derived from various organic precursors has been widely studied, this process may similarly be able to increase the pore volume and specific surface area of CDC. Oxidation of carbide-derived carbon in air and CO{sub 2} at different temperatures and times allows for significant increase in pore volume and specific surface area as well as control over average pore size with subnanometer accuracy. The effect of activation and associated changes in the pore volume and surface area on the hydrogen uptake are also discussed. - Graphical abstract: Carbide-derived carbons (CDC) provide great potential for sorption of toxicants and gas storage applications. Activation of CDC in air and CO{sub 2} at different temperatures and times is applied in order to maximize pore volume and specific surface area, and control the average pore size with subnanometer accuracy.

  4. Hybrid plasmonic microcavity with an air-filled gap for sensing applications

    NASA Astrophysics Data System (ADS)

    Zhang, Meng; Liu, Binbin; Wu, Genzhu; Chen, Daru

    2016-12-01

    In this paper, a novel hybrid plasmonic microcavity with air-filled regions in the low-permittivity dielectric gap is proposed for sensing applications. Compared with the conventional structure with homogeneous gap, the introduced air-filled regions could improve the key modal characteristics of the hybrid mode. Simulation results reveal that this kind of hybrid microcavity maintains low loss with high quality factor ∼3062, and high field confinement with small mode volume 0.891 μm3. Moreover, in the sensing applications, this hybrid microcavity features simultaneously large refractive index sensitivity of 100 nm/RIU (refractive index unit) and relatively high quality factor of 3062. Hence, it shows that the hybrid plasmonic microcavity has potential applications in ultra-compact refractive index sensor.

  5. Development of Porosity Measurement Method in Shale Gas Reservoir Rock

    NASA Astrophysics Data System (ADS)

    Siswandani, Alita; Nurhandoko, BagusEndar B.

    2016-08-01

    The pore scales have impacts on transport mechanisms in shale gas reservoirs. In this research, digital helium porosity meter is used for porosity measurement by considering real condition. Accordingly it is necessary to obtain a good approximation for gas filled porosity. Shale has the typical effective porosity that is changing as a function of time. Effective porosity values for three different shale rocks are analyzed by this proposed measurement. We develop the new measurement method for characterizing porosity phenomena in shale gas as a time function by measuring porosity in a range of minutes using digital helium porosity meter. The porosity of shale rock measured in this experiment are free gas and adsorbed gas porosoty. The pressure change in time shows that porosity of shale contains at least two type porosities: macro scale porosity (fracture porosity) and fine scale porosity (nano scale porosity). We present the estimation of effective porosity values by considering Boyle-Gay Lussaac approximation and Van der Waals approximation.

  6. Bulk densities and porosities of Cenozoic and Cretaceous basin-filling strata and Cretaceous and older basement rocks, Los Angeles Basin, California, determined from measurements of core samples

    USGS Publications Warehouse

    Beyer, L.A.; McCulloh, T.H.

    1998-01-01

    This report describes and provides a digital data file of selected bulk properties of subsurface rocks sampled in and around Los Angeles basin, California. Selected properties include measured dry bulk density (range 0.78 to 3.01 g/cm3), measured or estimated grain (matrix) density, calculated water saturated bulk density (range 1.47 to 3.01 g/cm3), calculated total porosity (range 0 to 69 porosity percent), geologic age, and lithology. Most of the rocks are conventional core samples taken from wells drilled by the petroleum industry. A small percentage of the core samples are from shallow borings. Rocks studied range in age from pre-Cambrian (?) to Recent and include sedimentary (98.8%), and volcanic, metamorphic and intrusive (1.2%) samples. Core samples studied were taken from measured drillhole depths that range from 35 to 20,234 ft (11 to 6,167 m). Version 1.0 of the data base (dated June 1998) contains information for 7378 samples from 234 wells, including two redrilled wells. This report/data base can be accessed on U. S. Geological Survey servers at http://geopubs.wr.usgs.gov/open-file/of98-788. Periodic additions to the on-line data base will be provided as new data is gathered.

  7. A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry.

    PubMed

    Murawski, Ł; Zielczyński, M; Golnik, N; Gryziński, M A

    2014-10-01

    A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge.

  8. Measurements of two types of dilatational waves in an air-filled unconsolidated sand

    SciTech Connect

    Hickey, C.J.; Sabatier, J.M.

    1997-07-01

    This study consists of laboratory measurements of dilatational waves propagating through an air-filled unconsolidated sand. One excitation technique consists of a loudspeaker suspended in the air above the packing of sand. A second excitation technique uses a mechanical shaker in contact with the sand. The transmitted signals are received using microphones and geophones located at various depths within the sand. An interpretation based on measured phase speeds indicates that the transmitted energy from the suspended loudspeaker source is partitioned primarily but not exclusively into the type-II dilatational wave. This wave attenuates rapidly and is only detected at depths of less than about 15 cm for this particular sample. At the deeper depths the detected signal is associated with the type-I dilatational wave. The mechanical shaker produces only a type-I dilatational wave. Both the geophone and microphone sensors can detect both types of dilatational waves. {copyright} {ital 1997 Acoustical Society of America.}

  9. Concentration of dimethylnitrosamine in the air of smoke-filled rooms

    SciTech Connect

    Stehlik, G.; Richter, O.; Altmann, H.

    1982-12-01

    In order to evaluate the contribution of volatile nitrosamines from tobacco smoke to indoor air pollution, N-nitroso-dimethylamine (NDMA) and N-nitroso-diethylamine (NDEA) were measured in indoor air under artificial and natural conditions. In controlled experiments under extreme conditions, we found that tobacco smoke-related NDMA levels above 0.07 ng/liter were associated with a highly irritating atmosphere which was scarcely tolerable to those present. In smoke-filled rooms under natural conditions NDMA levels ranged from 0.02 to 0.05 ng/liter except a minimum value of less than 0.01 ng/liter in a restaurant and a maximum of 0.07 ng/liter in a dancing bar. These NDMA levels are thus below comparable values reported by others. The NDMA/NDEA ratios found in air samples taken from some rooms under conditions of everyday life are quite different from those found in sidestream smoke of cigarettes. Irritation was not reported under natural conditions. From the results it is concluded that NDMA levels, measured under real life conditions, are usually not caused by tobacco smoke alone. Evidence for other sources of volatile nitrosamines is discussed.

  10. Curvature effects on axisymmetric instability of conduction regime in a tall air-filled annulus

    NASA Astrophysics Data System (ADS)

    Pécheux, J.; Le Quéré, P.; Abcha, F.

    1994-10-01

    This paper numerically studies curvature effects on the instability of the conduction regime of natural convection in a tall air-filled differentially heated annulus of vertical aspect ratio 16 by integrating the two-dimensional axisymmetric Navier-Stokes equations in the Boussinesq approximation. The numerical algorithm combines a pseudospectral Chebyshev space discretization with a second-order time-stepping scheme. It is shown that, in contrast with linear stability analysis of the conduction solution, the time-periodic cross-roll instability does not take place in finite aspect ratio cavities for small values of the radius ratio. For all values of the radius ratio transition to unsteadiness occurs through supercritical Hopf bifurcations. Extensive computations show very complex behaviors of the unsteady solutions depending on the radius ratio. The nature of the reverse transition to steady state that occurs for increasing value of the Rayleigh number is also found to depend strongly on the value of the radius ratio.

  11. Flow patterns of natural convection in an air-filled vertical cavity

    NASA Astrophysics Data System (ADS)

    Wakitani, Shunichi

    1998-08-01

    Flow patterns of two-dimensional natural convection in a vertical air-filled tall cavity with differentially heated sidewalls are investigated. Numerical simulations based on a finite difference method are carried out for a wide range of Rayleigh numbers and aspect ratios from the onset of the steady multicellular flow, through the reverse transition to the unicellular pattern, to the unsteady multicellular flow. For aspect ratios (height/width) from 10 to 24, the various cellular structures characterized by the number of secondary cells are clarified from the simulations by means of gradually increasing Rayleigh number to 106. Unsteady multicellular solutions are found in some region of Rayleigh numbers less than those at which the reverse transition has occurred.

  12. Mode-based microparticle conveyor belt in air-filled hollow-core photonic crystal fiber.

    PubMed

    Schmidt, Oliver A; Euser, Tijmen G; Russell, Philip St J

    2013-12-02

    We show how microparticles can be moved over long distances and precisely positioned in a low-loss air-filled hollow-core photonic crystal fiber using a coherent superposition of two co-propagating spatial modes, balanced by a backward-propagating fundamental mode. This creates a series of trapping positions spaced by half the beat-length between the forward-propagating modes (typically a fraction of a millimeter). The system allows a trapped microparticle to be moved along the fiber by continuously tuning the relative phase between the two forward-propagating modes. This mode-based optical conveyor belt combines long-range transport of microparticles with a positional accuracy of 1 µm. The technique also has potential uses in waveguide-based optofluidic systems.

  13. High-resolution ion pulse ionization chamber with air filling for the 222Rn decays detection

    NASA Astrophysics Data System (ADS)

    Gavrilyuk, Yu. M.; Gangapshev, A. M.; Gezhaev, A. M.; Etezov, R. A.; Kazalov, V. V.; Kuzminov, V. V.; Panasenko, S. I.; Ratkevich, S. S.; Tekueva, D. A.; Yakimenko, S. P.

    2015-11-01

    The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. The chamber is intended to register α-particles from the 222Rn and its daughter's decays in the filled air sample. The detector is less sensitive to electromagnetic pick-ups and mechanical noises. The digital pulse processing method is proposed to improve the energy resolution of the ion pulse ionization chamber. An energy resolution of 1.6% has been achieved for the 5.49 MeV α-line. The dependence of the energy resolution on high voltage and working media pressure has been investigated and the results are presented.

  14. Bubble absorption by an air-filled helically-supported capillary channel

    NASA Astrophysics Data System (ADS)

    Beheshtipour, Negar; Thiessen, David

    2016-11-01

    Gas-liquid phase separation under microgravity conditions where buoyancy is not active represents a challenge for two-phase liquid-continuous space systems. Similar challenges are present in micro-scale electrochemical systems on Earth that generate gas bubbles in geometries where surface tension prevails over gravity. A possible ground-based application would be the removal of carbon dioxide bubbles from large aspect ratio channels in a direct-methanol fuel cell that could otherwise occlude the channel. In this study we use a 3-mm diameter stretched stainless-steel spring coated with a superhydrophobic layer to create a helically-supported capillary channel. Such a channel that is submerged in water and filled with air while vented to the atmosphere was found to absorb a stream of 2.5-mm diameter air bubbles at a rate of at least 36 bubbles/s. An optical detector and high-speed imaging system have been used to study bubble absorption dynamics. A significant finding is that the initial attachment of the bubble to the channel that involves the rupture of a thin film of water happens in less than 1 ms. The rapid rupture of the water film separating the bubble from the channel might be attributed to the roughness of the hydrophobic coating.

  15. Controlled porosity in electrodes

    DOEpatents

    Chiang, Yet-Ming; Bae, Chang-Jun; Halloran, John William; Fu, Qiang; Tomsia, Antoni P.; Erdonmez, Can K.

    2015-06-23

    Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm.sup.2), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

  16. Packing Bunker and Pile Silos to Minimize Porosity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article discusses the issue of porosity (i.e., the portion of volume filled with gas) in silages. As porosity increases, the silage is subject to greater losses. Porosity can be reduced by adequately packing the crop at ensiling. To keep porosity below 40% a minimum bulk density of 44 lbs./cu. ...

  17. Autonomous generation of a thermoacoustic solitary wave in an air-filled tube

    NASA Astrophysics Data System (ADS)

    Shimizu, Dai; Sugimoto, Nobumasa

    2016-10-01

    Experiments are performed to demonstrate the autonomous generation of an acoustic solitary wave in an air-filled, looped tube with an array of Helmholtz resonators. The solitary wave is generated spontaneously due to thermoacoustic instability by a pair of stacks installed in the tube and subject to a temperature gradient axially. No external drivers are used to create initial disturbances. Once the solitary wave is generated, it keeps on propagating to circulate along the loop endlessly. The stacks, which are made of ceramics and of many pores of square cross section, are placed in the tube diametrically on exactly the opposite side of the loop, and they are sandwiched by hot and cold (ambient) heat exchangers. When the temperature gradient along both stacks is appropriate, pulses of smooth profiles are generated and propagated in both directions of the tube. From good agreements of not only the pressure profile measured but also the propagation speed with the theory, the pulse is identified as the acoustic solitary wave, and it can be called thermoacoustic solitary wave or thermoacoustic soliton corresponding to the soliton solution of the K-dV equation in one limit.

  18. The effects of porosity and permeability on fluid flow and heat transfer of multi walled carbon nano-tubes suspended in oil (MWCNT/Oil nano-fluid) in a microchannel filled with a porous medium

    NASA Astrophysics Data System (ADS)

    Nojoomizadeh, Mehdi; Karimipour, Arash

    2016-10-01

    The forced convection heat transfer and laminar flow in a two-dimensional microchannel filled with a porous medium is numerically investigated. The nano-particles which have been used are multi walled carbon nano-tubes (MWCNT) suspended in oil as the based fluid. The assumption of no-slip condition between the base fluid and nano-particles as well as the thermal equilibrium between them allows us to study the nanofluid in a single phase. The nanofluid flow through the microchannel has been modeled using the Darcy-Forchheimer equation. It is also assumed that there is a thermal equilibrium between the solid phase and the nanofluid for energy transfer. The walls of the microchannel are under the influence of a fluctuating heat flux. Also, the slip velocity boundary condition has been assumed along the walls. The effects of Darcy number, porosity and slip coefficients and Reynolds number on the velocity and temperature profiles and Nusselt number will be studied in this research.

  19. Detection of Air and Water-Filled Subsurface Defects in GFRP Composite Bridge Decks Using Infrared Thermography

    NASA Astrophysics Data System (ADS)

    Halabe, Udaya B.; Roy, M.; Klinkhachorn, P.; GangaRao, Hota V. S.

    2006-03-01

    Any discontinuity within a structural component influences the transmission of thermal energy through its thickness, which leads to differences in surface temperatures just above the defective and defect-free areas. The variation in the surface temperatures are recorded using a digital infrared camera and the thermal images (thermograms) are analyzed to locate the presence of subsurface defects such as debonds and delaminations within the structure. While past studies focused on detection of air-filled subsurface defects (debonds and delaminations) in fiber reinforced polymer (GFRP) composite bridge decks using infrared thermography, this paper includes the detection of fully and partially water-filled defects as well. Simulated water-filled defects were embedded within the flange-to-flange junction of adjacent GFRP bridge deck modules to create delaminations. The deck specimens were then tested before and after the application of a 3/8″ (9.5 mm) thick polymer concrete wearing surface. It was found that water-filled delaminations as small as 2″ × 2″ × 1/16″ (51 mm × 51 mm × 1.6 mm) could be detected in case of specimens without wearing surface, but this was not possible after application of the wearing surface. The heating source considered included heater and solar radiation. Use of cooling sources such as cold water and liquid carbon dioxide were also explored. These results helped establish the limits of detection for fully and partially water-filled delaminations using Infrared Thermograpy. Additional studies included the detection of debond between 2″ (51mm) thick asphalt overlay and the underlying composite deck and it was found that air-filled debonds as small as 4″ × 4″ × 1/16″ (102 mm × 102 mm × 1.6 mm) could be detected using heater as well as solar radiation as heat sources.

  20. Air-filled postcranial bones in theropod dinosaurs: physiological implications and the 'reptile'-bird transition.

    PubMed

    Benson, Roger B J; Butler, Richard J; Carrano, Matthew T; O'Connor, Patrick M

    2012-02-01

    Pneumatic (air-filled) postcranial bones are unique to birds among extant tetrapods. Unambiguous skeletal correlates of postcranial pneumaticity first appeared in the Late Triassic (approximately 210 million years ago), when they evolved independently in several groups of bird-line archosaurs (ornithodirans). These include the theropod dinosaurs (of which birds are extant representatives), the pterosaurs, and sauropodomorph dinosaurs. Postulated functions of skeletal pneumatisation include weight reduction in large-bodied or flying taxa, and density reduction resulting in energetic savings during foraging and locomotion. However, the influence of these hypotheses on the early evolution of pneumaticity has not been studied in detail previously. We review recent work on the significance of pneumaticity for understanding the biology of extinct ornithodirans, and present detailed new data on the proportion of the skeleton that was pneumatised in 131 non-avian theropods and Archaeopteryx. This includes all taxa known from significant postcranial remains. Pneumaticity of the cervical and anterior dorsal vertebrae occurred early in theropod evolution. This 'common pattern' was conserved on the line leading to birds, and is likely present in Archaeopteryx. Increases in skeletal pneumaticity occurred independently in as many as 12 lineages, highlighting a remarkably high number of parallel acquisitions of a bird-like feature among non-avian theropods. Using a quantitative comparative framework, we show that evolutionary increases in skeletal pneumaticity are significantly concentrated in lineages with large body size, suggesting that mass reduction in response to gravitational constraints at large body sizes influenced the early evolution of pneumaticity. However, the body size threshold for extensive pneumatisation is lower in theropod lineages more closely related to birds (maniraptorans). Thus, relaxation of the relationship between body size and pneumatisation preceded

  1. SU-E-T-297: Dosimetric Assessment of An Air-Filled Balloon Applicator in HDR Vaginal Cuff Brachytherapy Using the Monte Carlo Method

    SciTech Connect

    Jiang, H; Lee, Y; Pokhrel, D; Badkul, R

    2015-06-15

    Purpose: As an alternative to cylindrical applicators, air inflated balloon applicators have been introduced into HDR vaginal cuff brachytherapy treatment to achieve sufficient dose to vagina mucosa as well as to spare rectum and bladder. In general, TG43 formulae based treatment planning systems do not take into account tissue inhomogeneity, and air in the balloon applicator can cause higher delivered dose to mucosa than treatment plan reported. We investigated dosimetric effect of air in balloon applicator using the Monte Carlo method. Methods: The thirteen-catheter Capri applicator with a Nucletron Ir-192 seed was modeled for various balloon diameters (2cm to 3.5cm) using the MCNP Monte Carlo code. Ir-192 seed was placed in both central and peripheral catheters to replicate real patient situations. Existence of charged particle equilibrium (CPE) with air balloon was evaluated by comparing kerma and dose at various distances (1mm to 70mm) from surface of air-filled applicator. Also mucosa dose by an air-filled applicator was compared with by a water-filled applicator to evaluate dosimetry accuracy of planning system without tissue inhomogeneity correction. Results: Beyond 1mm from air/tissue interface, the difference between kerma and dose was within 2%. CPE (or transient CPE) condition was deemed existent, and in this region no electron transport was necessary in Monte Carlo simulations. At 1mm or less, the deviation of dose from kerma became more apparent. Increase of dose to mucosa depended on diameter of air balloon. The increment of dose to mucosa was 2.5% and 4.3% on average for 2cm and 3.5cm applicators, respectively. Conclusion: After introduction of air balloon applicator, CPE fails only at the proximity of air/tissue interface. Although dose to mucosa is increased, there is no significant dosimetric difference (<5%) between air and water filled applicators. Tissue inhomogeneity correction is not necessary for air-filled applicators.

  2. Intraoperative measurement of intraocular pressure in vitrectomized aphakic air-filled eyes using the Tono-Pen XL.

    PubMed

    Badrinath, S S; Vasudevan, R; Murugesan, R; Basti, S; Nicholson, A D; Singh, P; Gopal, L; Sharma, T; Rao, S B; Abraham, C

    1993-01-01

    The Tono-Pen XL (Bio-Rad, Santa Ana, CA) was compared with manometer readings for intraoperative measurement of intraocular pressure (IOP) in 40 eyes of 40 consecutive patients after vitrectomy, lensectomy, and fluid-air exchange. Tono-Pen readings corresponding to manometer readings of 10, 20, 30, 40, and 50 mmHg were obtained in a masked fashion with a randomized sequence of manometer readings. A correlation was obtained between the manometer and Tono-Pen readings (r = 0.96 in emmetropic eyes and r = 0.93 in myopic eyes). The regression curve that represents the calibration curve of Tono-Pen in terms of the manometer readings for air-filled vitrectomized eyes was obtained. Any Tono-Pen reading can be easily translated into the corresponding manometer reading by referring to the curve. The Tono-Pen can therefore be effectively used to accurately determine intraoperative IOP in eyes undergoing vitrectomy, lensectomy, and fluid-air exchange.

  3. Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber.

    PubMed

    Guichard, Florent; Giree, Achut; Zaouter, Yoann; Hanna, Marc; Machinet, Guillaume; Debord, Benoît; Gérôme, Frédéric; Dupriez, Pascal; Druon, Frédéric; Hönninger, Clemens; Mottay, Eric; Benabid, Fetah; Georges, Patrick

    2015-03-23

    We report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers.

  4. Influence of porosity on thermophysical properties of a composite

    NASA Astrophysics Data System (ADS)

    Grishaeva, N. Yu.; Ljukshin, B. A.; Strukov, Yu. S.; Bochkareva, S. A.

    2015-10-01

    In many modern information systems, the heat generated during the operation of electronic devices is usually dissipated by heat-conductive pads between the casing of the respective equipment and a massive base (platform). For newly developed pads, the promising materials are composites on the basis of various types of silicone rubber. At the same time, during the production of the pads without a vacuum setup, the material can contain air bubbles, which causes the porosity potentially negative for the thermal properties of the material. This work studies the thermal conductivity depending on the degree of silicone matrix filling by copper particles, introduced to improve thermal conductivity, and by air bubbles that are considered as reinforcing inclusions.

  5. Influence of porosity on thermophysical properties of a composite

    SciTech Connect

    Grishaeva, N. Yu. Ljukshin, B. A. Bochkareva, S. A.; Strukov, Yu. S.

    2015-10-27

    In many modern information systems, the heat generated during the operation of electronic devices is usually dissipated by heat-conductive pads between the casing of the respective equipment and a massive base (platform). For newly developed pads, the promising materials are composites on the basis of various types of silicone rubber. At the same time, during the production of the pads without a vacuum setup, the material can contain air bubbles, which causes the porosity potentially negative for the thermal properties of the material. This work studies the thermal conductivity depending on the degree of silicone matrix filling by copper particles, introduced to improve thermal conductivity, and by air bubbles that are considered as reinforcing inclusions.

  6. Step-Wise Velocity of an Air Bubble Rising in a Vertical Tube Filled with a Liquid Dispersion of Nanoparticles.

    PubMed

    Cho, Heon Ki; Nikolov, Alex D; Wasan, Darsh T

    2017-03-21

    The motion of air bubbles in tubes filled with aqueous suspensions of nanoparticles (nanofluids) is of practical interest for bubble jets, lab-on-a-chip, and transporting media. Therefore, the focus of this study is the dynamics of air bubbles rising in a tube in a nanofluid. Many authors experimentally and analytically proposed that the velocity of rising air bubbles is constant for long air bubbles suspended in a vertical tube in common liquids (e.g. an aqueous glycerol solution) when the capillary number is larger than 10(-4). For the first time, we report here a systematic study of an air bubble rising in a vertical tube in a nanofluid (e.g. an aqueous silica dioxide nanoparticle suspension, nominal particle size, 19 nm). We varied the bubble length scaled by the diameter of the tubes (L/D), the concentration of the nanofluid (10 and 12.5 v %), and the tube diameter (0.45, 0.47, and 0.50 cm). The presence of the nanoparticles creates a significant change in the bubble velocity compared with the bubble rising in the common liquid with the same bulk viscosity. We observed a novel phenomenon of a step-wise increase in the air bubble rising velocity versus bubble length for small capillary numbers less than 10(-7). This step-wise velocity increase versus the bubble length was not observed in a common fluid. The step-wise velocity increase is attributed to the nanoparticle self-layering phenomenon in the film adjacent to the tube wall. To elucidate the role of the nanoparticle film self-layering on the bubble rising velocity, the effect of the capillary number, the tube diameter (e.g. the capillary pressure), and nanofilm viscosity are investigated. We propose a model that takes into consideration the nanoparticle layering in the film confinement to explain the step-wise velocity phenomenon versus the length of the bubble. The oscillatory film interaction energy isotherm is calculated and the Frenkel approach is used to estimate the film viscosity.

  7. Multiple Solutions in Natural Convection in an Air Filled Square Enclosure: Fractal Dimension of Attractors

    NASA Astrophysics Data System (ADS)

    Aklouche Benouaguef, S.; Zeghmati, B.; Bouhadef, K.; Daguenet, M.

    In this study, we investigated numerically the transient natural convection in a square cavity with two horizontal adiabatic sides and vertical walls composed of two regions of same size maintained at different temperatures. The flow has been assumed to be laminar and bi-dimensional. The governing equations written in dimensionless form and expressed in terms of stream function and vorticity, have been solved using the Alternating Direction Implicit (ADI) method and the GAUSS elimination method. Calculations were performed for air (Pr = 0.71), with a Rayleigh number varying from 2.5x105 to 3.7x106. We analysed the effect of the Rayleigh number on the route to the chaos of the system. The first transition has been found from steady-state to oscillatory flow and the second is a subharmonic bifurcation as the Rayleigh number is increased further. For sufficiently small Rayleigh numbers, present results show that the flow is characterized by four cells with horizontal and vertical symmetric axes. The attractor bifurcates from a stable fixed point to a limit cycle for a Rayleigh number varying from 2.5x105 to 2.51x105. A limit cycle settles from Ra = 3x105 and persists until Ra = 5x105. At a Rayleigh number of 2.5x105 the temporal evolution of the Nusselt number Nu(t) was stationary. As the Rayleigh number increases, the flow becomes unstable and bifurcates to a time periodic solution at a critical Rayleigh number between 2.5x105 and 2.51x105. After the first HOPF bifurcation at Ra = 2.51x105, the oscillatory flow undergoes several bifurcations and ultimately evolves into a chaotic flow.

  8. Fabrication of dual porosity electrode structure

    DOEpatents

    Smith, J.L.; Kucera, E.H.

    1991-02-12

    A substantially entirely fibrous ceramic is described which may have dual porosity of both micro and macro pores. Total porosity may be 60-75% by volume. A method of spraying a slurry perpendicularly to an ambient stream of air is disclosed along with a method of removing binders without altering the fiber morphology. Adding fine ceramic particulates to the green ceramic fibers enhances the sintering characteristics of the fibers. 3 figures.

  9. Fabrication of dual porosity electrode structure

    DOEpatents

    Smith, James L.; Kucera, Eugenia H.

    1991-01-01

    A substantially entirely fibrous ceramic which may have dual porosity of both micro and macro pores. Total porosity may be 60-75% by volume. A method of spraying a slurry perpendicularly to an ambient stream of air is disclosed along with a method of removing binders without altering the fiber morphology. Adding fine ceramic particulates to the green ceramic fibers enhances the sintering characteristics of the fibers.

  10. Microparticles with hierarchical porosity

    DOEpatents

    Petsev, Dimiter N; Atanassov, Plamen; Pylypenko, Svitlana; Carroll, Nick; Olson, Tim

    2012-12-18

    The present disclosure provides oxide microparticles with engineered hierarchical porosity and methods of manufacturing the same. Also described are structures that are formed by templating, impregnating, and/or precipitating the oxide microparticles and method for forming the same. Suitable applications include catalysts, electrocatalysts, electrocatalysts support materials, capacitors, drug delivery systems, sensors and chromatography.

  11. Understanding the Relationship Between Filling Pattern and Part Quality in Die Casting

    SciTech Connect

    Jerald Brevick; R. Allen Miller

    2004-03-15

    The overall objective of this research project was to investigate phenomena involved in the filling of die cavities with molten alloy in the cold chamber die-casting process. It has long been recognized that the filling pattern of molten metal entering a die cavity influences the quality of die-cast parts. Filling pattern may be described as the progression of molten metal filling the die cavity geometry as a function of time. The location, size and geometric configuration of points of metal entry (gates), as well as the geometry of the casting cavity itself, have great influence on filling patterns. Knowledge of the anticipated filling patterns in die-castings is important for designers. Locating gates to avoid undesirable flow patterns that may entrap air in the casting is critical to casting quality - as locating vents to allow air to escape from the cavity (last places to fill). Casting quality attributes that are commonly flow related are non-fills, poor surface finish, internal porosity due to trapped air, cold shuts, cold laps, flow lines, casting skin delamination (flaking), and blistering during thermal treatment.

  12. Enhancement of fill factor in air-processed inverted organic solar cells using self-assembled monolayer of fullerene catechol

    NASA Astrophysics Data System (ADS)

    Jeon, Il; Ogumi, Keisuke; Nakagawa, Takafumi; Matsuo, Yutaka

    2016-08-01

    [60]Fullerene catechol self-assembled monolayers were prepared and applied to inverted organic solar cells by an immersion method, and their energy conversion properties were measured. By introducing fullerenes at the surface, we improved the hole-blocking capability of electron-transporting metal oxide, as shown by the fill factor enhancement. The fullerene catechol-treated TiO x -containing device gave a power conversion efficiency (PCE) of 2.81% with a fill factor of 0.56 while the non treated device gave a PCE of 2.46% with a fill factor of 0.49. The solar cell efficiency improved by 13% compared with the non treated reference device.

  13. Evolution of porosity and geochemistry in Marcellus Formation black shale during weathering

    SciTech Connect

    Jin, Lixin; Mathur, Ryan; Rother, Gernot; Cole, David; Bazilevskaya, Ekaterina; Williams, Jennifer; Carone, Alex; Brantley, Susan L

    2013-01-01

    Soils developed on the Oatka Creek member of the Marcellus Formation in Huntingdon, Pennsylvania were analyzed to understand the evolution of black shale matrix porosity and the associated changes in elemental and mineralogical composition during infiltration of water into organic-rich shale. Making the reasonable assumption that soil erosion rates are the same as those measured in a nearby location on a less organic-rich shale, we suggest that soil production rates have on average been faster for this black shale compared to the gray shale in similar climate settings. This difference is attributed to differences in composition: both shales are dominantly quartz, illite, and chlorite, but the Oatka Creek member at this location has more organic matter (1.25 wt% organic carbon in rock fragments recovered from the bottom of the auger cores and nearby outcrops) and accessory pyrite. During weathering, the extremely low-porosity bedrock slowly disaggregates into shale chips with intergranular pores and fractures. Some of these pores are either filled with organic matter or air-filled but remain unconnected, and thus inaccessible to water. Based on weathering bedrock/soil profiles, disintegration is initiated with oxidation of pyrite and organic matter, which increases the overall porosity and most importantly allows water penetration. Water infiltration exposes fresh surface area and thus promotes dissolution of plagioclase and clays. As these dissolution reactions proceed, the porosity in the deepest shale chips recovered from the soil decrease from 9 to 7 % while kaolinite and Fe oxyhydroxides precipitate. Eventually, near the land surface, mineral precipitation is outcompeted by dissolution or particle loss of illite and chlorite and porosity in shale chips increases to 20%. As imaged by computed tomographic analysis, weathering causes i) greater porosity, ii) greater average length of connected pores, and iii) a more branched pore network compared to the

  14. Liquids with permanent porosity

    NASA Astrophysics Data System (ADS)

    Giri, Nicola; Del Pópolo, Mario G.; Melaugh, Gavin; Greenaway, Rebecca L.; Rätzke, Klaus; Koschine, Tönjes; Pison, Laure; Gomes, Margarida F. Costa; Cooper, Andrew I.; James, Stuart L.

    2015-11-01

    Porous solids such as zeolites and metal-organic frameworks are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption-desorption cycles, but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages, but permanent porosity is not associated with conventional liquids. Here we report free-flowing liquids whose bulk properties are determined by their permanent porosity. To achieve this, we designed cage molecules that provide a well-defined pore space and that are highly soluble in solvents whose molecules are too large to enter the pores. The concentration of unoccupied cages can thus be around 500 times greater than in other molecular solutions that contain cavities, resulting in a marked change in bulk properties, such as an eightfold increase in the solubility of methane gas. Our results provide the basis for development of a new class of functional porous materials for chemical processes, and we present a one-step, multigram scale-up route for highly soluble ‘scrambled’ porous cages prepared from a mixture of commercially available reagents. The unifying design principle for these materials is the avoidance of functional groups that can penetrate into the molecular cage cavities.

  15. Porosity in polysilsesquioxane xerogels

    SciTech Connect

    LOY,DOUGLAS A.; SCHNEIDER,DUANE A.; BAUGHER,BRIGITTA M.; RAHIMIAN,KAMYAR

    2000-05-09

    Polysilsesquioxanes, [RSiO{sub 1.5}]{sub n} are a class of hybrid organic-inorganic materials in which silicon atoms are linked with up to three siloxane bonds to other monomer units in the polymer and the organic group is a pendent functionality. Polysilsesquioxanes are prepared by the hydrolysis and condensation of organotrialkoxysilanes (Scheme l). Organotrialkoxysilanes RSi(OR{prime}){sub 3}, have been extensively used as coupling agents for composites or surface treatments for materials. Polysilsesquioxanes have become increasingly popular for generating specialty coatings such as low k dielectric materials for microelectronic applications. While there is extensive information on the formation of polysilsesquioxanes, there has not been a survey of the ability of organotrialkoxysilanes to form gels until recently. The formation of polysilsesquioxanes gels has been shown to be very sensitive to the nature of the organic group. Many monomers will only form soluble oligomers or polymers upon hydrolysis and condensation, even when the reaction is conducted solvent-free with neat monomer and aqueous catalyst. Furthermore, there is little information concerning the influence of the organic group, R, on the porosity of the polysilsesquioxanes gels that are formed. In this paper the authors describe the preparation of polysilsesquioxane gels where R = H, methyl, ethyl, cyanoethyl, vinyl, dodecyl, hexadecyl, octadecyl, chloromethyl, and chloromethylphenyl, and the characterization of the porosity of the respective xerogels. Gels were prepared from the hydrolysis and condensation of organotrimethoxysilanes, RSi(OEt){sub 3}, and organotriethoxy-silanes, RSi(OEt){sub 3}.

  16. Numerical study of porosity in titanium dental castings.

    PubMed

    Wu, M; Sahm, P R; Augthun, M; Spiekermann, H; Schädlich-Stubenrauch, J

    1999-09-01

    A commercial software package, MAGMASOFT (MAGMA Giessereitechnologie GmbH, Aachen, Germany), was used to study shrinkage and gas porosity in titanium dental castings. A geometrical model for two simplified tooth crowns connected by a connector bar was created. Both mold filling and solidification of this casting model were numerically simulated. Shrinkage porosity was quantitatively predicted by means of a built-in feeding criterion. The risk of gas pore formation was investigated using the numerical filling and solidification results. The results of the numerical simulations were compared with experiments, which were carried out on a centrifugal casting machine with an investment block mold. The block mold was made of SiO2 based slurry with a 1 mm thick Zr2 face coat to reduce metal-mold reactions. Both melting and casting were carried out under protective argon (40 kPa). The finished castings were sectioned and the shrinkage porosity determined. The experimentally determined shrinkage porosity coincided with the predicted numerical simulation results. No apparent gas porosity was found in these model castings. Several running and gating systems for the above model casting were numerically simulated. An optimized running and gating system design was then experimentally cast, which resulted in porosity-free castings.

  17. Quantification of VX vapor in ambient air by liquid chromatography isotope dilution tandem mass spectrometric analysis of glass bead filled sampling tubes.

    PubMed

    Evans, Ronald A; Smith, Wendy L; Nguyen, Nam-Phuong; Crouse, Kathy L; Crouse, Charles L; Norman, Steven D; Jakubowski, E Michael

    2011-02-15

    An analysis method has been developed for determining low parts-per-quadrillion by volume (ppqv) concentrations of nerve agent VX vapor actively sampled from ambient air. The method utilizes glass bead filled depot area air monitoring system (DAAMS) sampling tubes with isopropyl alcohol extraction and isotope dilution using liquid chromatography coupled with a triple-quadrupole mass spectrometer (LC/MS/MS) with positive ion electrospray ionization for quantitation. The dynamic range was from one-tenth of the worker population limit (WPL) to the short-term exposure limit (STEL) for a 24 L air sample taken over a 1 h period. The precision and accuracy of the method were evaluated using liquid-spiked tubes, and the collection characteristics of the DAAMS tubes were assessed by collecting trace level vapor generated in a 1000 L continuous flow chamber. The method described here has significant improvements over currently employed thermal desorption techniques that utilize a silver fluoride pad during sampling to convert VX to a higher volatility G-analogue for gas chromatographic analysis. The benefits of this method are the ability to directly analyze VX with improved selectivity and sensitivity, the injection of a fraction of the extract, quantitation using an isotopically labeled internal standard, and a short instrument cycle time.

  18. Evolution of porosity and geochemistry in Marcellus Formation black shale during weathering

    SciTech Connect

    Jin, Lixin; Ryan, Mathur; Rother, Gernot; Cole, David; Bazilevskaya, Ekaterina; Williams, Jennifer; Alex, Carone; Brantley, S. L.

    2013-01-01

    Soils developed on the Oatka Creek member of the Marcellus Formation in Huntingdon, Pennsylvania were analyzed to understand the evolution of black shale matrix porosity and the associated changes in elemental and mineralogical composition during infiltration of water into organic-rich shale. Making the reasonable assumption that soil erosion rates are the same as those measured in a nearby location on a less organic-rich shale, we suggest that soil production rates have on average been faster for this black shale compared to the gray shale in similar climate settings. This difference is attributed to differences in composition: both shales are dominantly quartz, illite, and chlorite, but the Oatka Creek member at this location has more organic matter (1.25 wt.% organic carbon in rock fragments recovered from the bottom of the auger cores and nearby outcrops) and accessory pyrite. During weathering, the extremely low-porosity bedrock slowly disaggregates into shale chips with intergranular pores and fractures. Some of these pores are eitherfilled with organic matter or air-filled but remain unconnected, and thus inaccessible to water. Based on weathering bedrock/soil profiles, disintegration is initiated with oxidation of pyrite and organic matter, which increases the overall porosity and most importantly allows water penetration. Water infiltration exposes fresh surface area and thus promotes dissolution of plagioclase and clays. As these dissolution reactions proceed, the porosity in the deepest shale chips recovered from the soil decrease from 9 to 7% while kaolinite and Fe oxyhydroxides precipitate. Eventually, near the land surface, mineral precipitation is outcompeted by dissolution or particle loss of illite and chlorite and porosity in shale chips increases to 20%. As imaged by computed tomographic analysis, weathering causes i) greater porosity, ii) greater average length of connected pores, and iii) a more branched pore network compared to the unweathered

  19. The performance of a two-layer biotrickling filter filled with new mixed packing materials for the removal of H2S from air.

    PubMed

    Chen, Yingwen; Wang, Xiaojun; He, Shuo; Zhu, Shemin; Shen, Shubao

    2016-01-01

    In the work described here, a two-layer biotrickling filter filled with new packing materials was used to remove H2S from air. The upper layer of the filter was packed with activated carbon-loaded polyurethane, whereas the lower layer was filled with modified organism-suspended fillers. The effects of inlet load, empty bed residence time (EBRT) from 79 s to 53 s, pH and contaminant starvation time were investigated. For loads of 15-50 g/(m(3) h), the average removal efficiency (RE) was higher than 96% under a consistent supply of pollutants. The critical elimination capacity was 39.95 g/(m(3) h) for an EBRT of 53 s with an RE of 99.9%. The two-layer BTF was capable of withstanding contaminant starvation periods for 1.5 d and 7 d with only a few hours of recovery time. The biodegradation kinetics was studied using Michaelis-Menten type equations under different EBRTs. At an EBRT of 66 s, the optimal kinetic constants rmax and Km were 333.3 g/(m(3) h) and 0.93 g/m(3), respectively. During the operation, the two-layer BTF performed well under various reasonable conditions.

  20. Stability of two-dimensional (2D) natural convection flows in air-filled differentially heated cavities: 2D/3D disturbances

    NASA Astrophysics Data System (ADS)

    Xin, Shihe; Le Quéré, Patrick

    2012-06-01

    Following our previous two-dimensional (2D) studies of flows in differentially heated cavities filled with air, we studied the stability of 2D natural convection flows in these cavities with respect to 3D periodic perturbations. The basis of the numerical methods is a time-stepping code using the Chebyshev spectral collocation method and the direct Uzawa method for velocity-pressure coupling. Newton's iteration, Arnoldi's method and the continuation method have been used in order to, respectively, compute the 2D steady-state base solution, estimate the leading eigenmodes of the Jacobian and perform linear stability analysis. Differentially heated air-filled cavities of aspect ratios from 1 to 7 were investigated. Neutral curves (Rayleigh number versus wave number) have been obtained. It turned out that only for aspect ratio 7, 3D stationary instability occurs at slightly higher Rayleigh numbers than the onset of 2D time-dependent flow and that for other aspect ratios 3D instability always takes place before 2D time-dependent flows. 3D unstable modes are stationary and anti-centro-symmetric. 3D nonlinear simulations revealed that the corresponding pitchfork bifurcations are supercritical and that 3D instability leads only to weak flow in the third direction. Further 3D computations are also performed at higher Rayleigh number in order to understand the effects of the weak 3D fluid motion on the onset of time-dependent flow. 3D flow structures are responsible for the onset of time-dependent flow for aspect ratios 1, 2 and 3, while for larger aspect ratios they do not alter the transition scenario, which was observed in the 2D cases and that vertical boundary layers become unstable to traveling waves.

  1. Mechanistic Effects of Porosity on Structural Composite Materials

    NASA Astrophysics Data System (ADS)

    Siver, Andrew

    As fiber reinforced composites continue to gain popularity as primary structures in aerospace, automotive, and powersports industries, quality control becomes an extremely important aspect of materials and mechanical engineering. The ability to recognize and control manufacturing induced defects can greatly reduce the likelihood of unexpected catastrophic failure. Porosity is the result of trapped volatiles or air bubbles during the layup process and can significantly compromise the strength of fiber reinforced composites. A comprehensive study was performed on an AS4C-UF3352 TCR carbon fiber-epoxy prepreg system to determine the effect of porosity on flexural, shear, low-velocity impact, and damage residual strength properties. Autoclave cure pressure was controlled to induce varying levels of porosity to construct six laminates with porosity concentrations between 0-40%. Porosity concentrations were measured using several destructive and nondestructive techniques including resin burnoff, sectioning and optical analysis, and X-ray computed tomography (CT) scanning. Ultrasonic transmission, thermography, and CT scanning provided nondestructive imaging to evaluate impact damage. A bilinear relationship accurately characterizes the change in mechanical properties with increasing porosity. Strength properties are relatively unaffected when porosity concentrations are below approximately 2.25% and decrease linearly by up to 40% in high porosity specimens.

  2. Thermoelectric materials having porosity

    DOEpatents

    Heremans, Joseph P.; Jaworski, Christopher M.; Jovovic, Vladimir; Harris, Fred

    2014-08-05

    A thermoelectric material and a method of making a thermoelectric material are provided. In certain embodiments, the thermoelectric material comprises at least 10 volume percent porosity. In some embodiments, the thermoelectric material has a zT greater than about 1.2 at a temperature of about 375 K. In some embodiments, the thermoelectric material comprises a topological thermoelectric material. In some embodiments, the thermoelectric material comprises a general composition of (Bi.sub.1-xSb.sub.x).sub.u(Te.sub.1-ySe.sub.y).sub.w, wherein 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 1.8.ltoreq.u.ltoreq.2.2, 2.8.ltoreq.w.ltoreq.3.2. In further embodiments, the thermoelectric material includes a compound having at least one group IV element and at least one group VI element. In certain embodiments, the method includes providing a powder comprising a thermoelectric composition, pressing the powder, and sintering the powder to form the thermoelectric material.

  3. Filling a Conical Cavity

    NASA Astrophysics Data System (ADS)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  4. Data Qualification Report: Calculated Porosity and Porosity-Derived Values for Lithostratigraphic Units for use on the Yucca Mountain Project

    SciTech Connect

    P. Sanchez

    2001-05-30

    The qualification is being completed in accordance with the Data Qualification Plan DQP-NBS-GS-000006, Rev. 00 (CRWMS M&O 2001). The purpose of this data qualification activity is to evaluate for qualification the unqualified developed input and porosity output included in Data Tracking Number (DTN) M09910POROCALC.000. The main output of the analyses documented in DTN M09910POROCALC.000 is the calculated total porosity and effective porosity for 40 Yucca Mountain Project boreholes. The porosity data are used as input to Analysis Model Report (AMR) 10040, ''Rock Properties Model'' (MDL-NBS-GS-000004, Rev. 00), Interim Change Notice [ICN] 02 (CRWMS M&O 2000b). The output from the rock properties model is used as input to numerical physical-process modeling within the context of a relationship developed in the AMR between hydraulic conductivity, bound water and zeolitic zones for use in the unsaturated zone model. In accordance with procedure AP-3.15Q, the porosity output is not used in the direct calculation of Principal Factors for post-closure safety or disruptive events. The original source for DTN M09910POROCALC.000 is a Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M&O) report, ''Combined Porosity from Geophysical Logs'' (CRWMS M&O 1999a and hereafter referred to as Rael 1999). That report recalculated porosity results for both the historical boreholes covered in Nelson (1996), and the modern boreholes reported in CRWMS M&O (1996a,b). The porosity computations in Rael (1999) are based on density-porosity mathematical relationships requiring various input parameters, including bulk density, matrix density and air and/or fluid density and volumetric water content. The main output is computed total porosity and effective porosity reported on a foot-by-foot basis for each borehole, although volumetric water content is derived from neutron data as an interim output. This qualification report uses technical assessment and

  5. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  6. Dual porosity gas evolving electrode

    DOEpatents

    Townsend, Carl W.

    1994-01-01

    A dual porosity electrode for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

  7. Dual porosity gas evolving electrode

    DOEpatents

    Townsend, C.W.

    1994-11-15

    A dual porosity electrode is described for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

  8. The Porosity of 433 Eros

    NASA Technical Reports Server (NTRS)

    Britt, D. T.; Yeomans, Donald K.; Consolmagno, G. J.

    2001-01-01

    Data from the NEAR mission show the bulk density of 433 Eros is 2.67 g/cm 3 . Given an L or LL composition, the bulk porosity of Eros is in the range of 25-29% and the macroporosity is 14-18%. This is consistent with a fractured, but coherent asteroid. Additional information is contained in the original extended abstract.

  9. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    NASA Astrophysics Data System (ADS)

    Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

    2015-04-01

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  10. Numerical simulation of porosity-free titanium dental castings.

    PubMed

    Wu, M; Augthun, M; Schädlich-Stubenrauch, J; Sahm, P R; Spiekermann, H

    1999-08-01

    The objective of this research was to analyse, predict and control the porosity in titanium dental castings by the use of numerical simulation. A commercial software package (MAGMASOFT) was used. In the first part of the study, a model casting (two simplified tooth crowns connected by a connector bar) was simulated to analyse shrinkage porosity. Secondly, gas pores were numerically examined by means of a ball specimen with a "snake" sprue. The numerical simulation results were compared with the experimental casting results, which were made on a centrifugal casting machine. The predicted shrinkage levels coincided well with the experimentally determined levels. Based on the above numerical analyses, an optimised running and gating system design for the crown model was proposed. The numerical filling and solidification results of the ball specimen showed that this simulation model could be helpful for the explanation of the experimentally indicated gas pores. It was concluded that shrinkage porosity in titanium dental casting was predictable, and it could be minimised by improving the running and gating system design. Entrapped gas pores can be explained from the simulation results of the mould filling and solidification.

  11. Measurement of the open porosity of agricultural soils with acoustic waves

    NASA Astrophysics Data System (ADS)

    Luong, Jeanne; Mercatoris, Benoit; Destain, Marie-France

    2015-04-01

    soil, since there are more voids filled with air and water, increasing the viscous losses. Fellah et al. (2003) showed that porosity can be determined from phase speed and reflection coefficient. The propagation of acoustic waves in soil is investigated to develop a rapid method for the quantification of the porosity level of agricultural soils. In the present contribution, correlations are determined between the acoustic signatures of agricultural soil in function of its structural properties. In laboratory, compression tests are performed on unsaturated soil samples to reproduce different porosity levels. Ultrasonic pulses are sent through the considered samples. The propagated signals are treated in both time and frequency domains in order to determine the speed of the phase velocity and the reflection. Porosity is then determined and compared with water content measured by gravimetric method. Alaoui, A., Lipiec, J. & Gerke, H.H., 2011. A review of the changes in the soil pore system due to soil deformation: A hydrodynamic perspective. Soil and Tillage Research, 115-116, pp.1-15. Fellah Z.E.A., Berger S., Lauriks W., Depollier C., Aristegui C., Chapelon J.Y., 2003. Measuring the porosity and the tortuosity of porous materials via reflected waves at oblique incidence. The Journal of the Acoustical Society of America 113 (5), pp 2424-2433 Hamza, M.A. & Anderson, W.K., 2005. Soil compaction in cropping systems. Soil and Tillage Research, 82(2), pp.121-145. Lu, Z., 2005. Role of hysteresis in propagating acousitcs waves in soils. Geophysical Research Letter, pp.32:1-4. Lu, Z., Hickey, C.J. & Sabatier, J.M., 2004. Effects of compaction on the acoustic velocity in soils. Soil Science Society of America Journal, 68(1), pp.7-16. Lu, Z. & Sabatier, J.M., 2009. Effects of soil water potential and moisture content on sound speed. Soil Science Society of America Journal, 73(5), pp.1614-1625. Le Maitre, D.C., Kotzee, I.M. & O'Farrell, P.J., 2014. Impacts of land-cover change on

  12. Porosity and mechanical properties of zirconium ceramics

    NASA Astrophysics Data System (ADS)

    Buyakova, S.; Sablina, T.; Kulkov, S.

    2015-11-01

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO2(MgO), ZrO2(Y2O3) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO2 powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO2 grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  13. Porosity and mechanical properties of zirconium ceramics

    SciTech Connect

    Buyakova, S. Kulkov, S.; Sablina, T.

    2015-11-17

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO{sub 2}(MgO), ZrO{sub 2}(Y{sub 2}O{sub 3}) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO{sub 2} powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO{sub 2} grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  14. Modeling fracture porosity evolution in dolostone

    NASA Astrophysics Data System (ADS)

    Gale, Julia F. W.; Lander, Robert H.; Reed, Robert M.; Laubach, Stephen E.

    2010-09-01

    Opening-mode fractures in dolostones buried to depths of ˜1-5 km contain synkinematic dolomite cement, the amount and internal structure of which has a systematic relationship to fracture size. Narrow fractures (<0.01 mm) typically seal completely with either massive cement or cement with a crack-seal texture that indicates multiple incremental openings. Wider fractures can preserve considerable effective porosity, but anomalously thick dolomite cement bridges are commonly present in fractures that are otherwise lined with a thin veneer of cement. Dolomite bridges resemble quartz bridges that are common in fractured sandstones. We developed a geometric crystal growth model for synkinematic dolomite fracture fill in fractured dolostones, where periodic incremental fracture-opening events are introduced with concurrent cement growth. We assumed constant temperature and supersaturation with respect to dolomite. A key assumption in the model is that rapid dolomite accumulation within bridges is governed by high cement-growth rates on repeatedly broken grain surfaces during the process of crack seal. Slower cement-growth rates occur on euhedral crystals. This assumption is made on the basis of a comparison with quartz cement growth in fractured sandstones. Simulations with different fracture-opening rates mimic bridge and lining cement morphologies, including characteristic rhombic shapes of dolomite bridges.

  15. Porosity in metal-organic framework glasses.

    PubMed

    Thornton, A W; Jelfs, K E; Konstas, K; Doherty, C M; Hill, A J; Cheetham, A K; Bennett, T D

    2016-03-07

    The porosity of a glass formed by melt-quenching a metal-organic framework, has been characterized by positron annihilation lifetime spectroscopy. The results reveal porosity intermediate between the related open and dense crystalline frameworks ZIF-4 and ZIF-zni. A structural model for the glass was constructed using an amorphous polymerization algorithm, providing additional insight into the gas-inaccessible nature of porosity and the possible applications of hybrid glasses.

  16. Porosity determination of thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Van Roode, Mark; Beardsley, Brad

    1988-01-01

    Coating porosity is believed to be a critical factor for the thermal conductivity of thermal barrier coatings (TBCs). A number of different techniques have been used to determine the porosities of thermal barrier coatings for diesel applications as part of a NASA/DOE sponsored study. A comparison is made between methods based on water immersion, optical microscopy, eddy current thickness measurements, and Archimedes principle for TBC porosity determination.

  17. Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

    SciTech Connect

    B.M. Freifeild

    2001-10-18

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  18. Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing

    SciTech Connect

    Freifeld, Barry Mark

    2001-12-01

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  19. Controls on porosity development in the Devonian Reservoir at Dolarhide Field

    SciTech Connect

    Saller, A.; Miller, J. ); Van Horn, D. )

    1990-05-01

    Devonian strata in the Dollarhide anticline originally contained 138 million bbl of oil. Porosity distribution is controlled by depositional facies. Devonian shata contain five main lithologies (from bottom to top). (1) Nonporous, microcrystalline chert and dolomite deposited as carbonate and siliceous mud in a basinal enviroment. (2) Burrowed chert-dolomite (10-35 ft thick) with variable porosity accumulated as siliceous sponge spicules and carbonate mud in a low-energy slope environment. (3) Laminated tripolitic chert (0-65 ft) deposited as a spiculitic sand in submarine channels in a slope environment. It has excellent porosity, mainly molds of sponge spicules. (4) Bioclastic limestone (47-92 ft) accumulated as a crinoidal grainstone in a moderate- to high-energy, outer shelf environment. Calcite cementation occluded virtually all porosity. (5) Upper dolomite (50-90 ft) consists of 1-3-ft-thick sequences of dolomitized peloidal grainstone capped by fine-grained chert. The grainstone was deposited in high-energy, shallow-subtidal and tidal-flat environments and has variable porosity. Deposition of the 200-ft-thick Devonian section occurred during a major progradation of shelf and slope facies. Porosity occurs in two stratigraphic zones separated by tight bioclastic limestone. The upper porosity zone (0-90 ft in upper dolomite) is heterogeneous with stratified porosity that bifurcates, coalesces, and pinches out. The lower porosity zone (laminated tripolitic chert and burrowed chert-dolomite) is homogeneous, with high porosity (commonly 25-35%), moderate permeability (5-20 md), and, in the southern part of the field, no distinct vertical permeability barriers. Thickness of the lower reservoir is variable (0-100 ft) with elongate thicks where sponge spicule sands filled channels.

  20. Effects of a random porosity model on double diffusive natural convection in a porous medium enclosure

    SciTech Connect

    Fu, W.S.; Ke, W.W.

    2000-01-01

    A double diffusive natural convection in a rectangular enclosure filled with porous medium is investigated numerically. The distribution of porosity is based upon the random porosity model. The Darcy-Brinkman-Forchheimer model is used and the factors of heat flux, mean porosity and standard deviation are taken into consideration. The SIMPLEC method with iterative processes is adopted to solve the governing equations. The effects of the random porosity model on the distributions of local Nusselt number are remarkable and the variations of the local Nusselt number become disordered. The contribution of latent heat transfer to the total heat transfer of the high Rayleigh number is larger than that of the low Rayleigh number and the variations of the latent heat transfer are not in order.

  1. Whisker Formation in Porosity in Al Alloys

    NASA Astrophysics Data System (ADS)

    Griffiths, William David; Elsayed, Ahmed; El-Sayed, Mahmoud Ahmed

    2016-12-01

    An examination of the fracture surfaces of tensile test bars from Al alloy castings held in the liquid state for up to 20 minutes revealed porosity which in some cases contained whisker-like features. Energy-dispersive X-ray analysis in a SEM suggested that these might be oxide whiskers forming in an oxide-related pore or double oxide film defect. Such entrainment defects (also known as bifilms) may entrap a small amount of the local atmosphere when they form and become incorporated into the liquid metal. This atmosphere may be predominantly air, which then subsequently reacts with the surrounding melt, firstly by reaction with oxygen and secondly by reaction with nitrogen. A CFD model of the heat distribution associated with the reactions between the interior atmosphere of a double oxide film defect and the surrounding liquid alloy suggested that highly localized increases in temperature, up to about 2000 K to 5000 K (1727 °C to 4727 °C), could occur, over a scale of a few hundred micrometers. Such localized increases in temperature might lead to the evaporation or disassociation of oxide within the pore, followed by condensation, to form the whisker structures observed. Hydrogen might also be expected to diffuse into the bifilm and may play a role in the chemical reactions associated with the development of the bifilm.

  2. Olive Crown Porosity Measurement Based on Radiation Transmittance: An Assessment of Pruning Effect

    PubMed Central

    Castillo-Ruiz, Francisco J.; Castro-Garcia, Sergio; Blanco-Roldan, Gregorio L.; Sola-Guirado, Rafael R.; Gil-Ribes, Jesus A.

    2016-01-01

    Crown porosity influences radiation interception, air movement through the fruit orchard, spray penetration, and harvesting operation in fruit crops. The aim of the present study was to develop an accurate and reliable methodology based on transmitted radiation measurements to assess the porosity of traditional olive trees under different pruning treatments. Transmitted radiation was employed as an indirect method to measure crown porosity in two olive orchards of the Picual and Hojiblanca cultivars. Additionally, three different pruning treatments were considered to determine if the pruning system influences crown porosity. This study evaluated the accuracy and repeatability of four algorithms in measuring crown porosity under different solar zenith angles. From a 14° to 30° solar zenith angle, the selected algorithm produced an absolute error of less than 5% and a repeatability higher than 0.9. The described method and selected algorithm proved satisfactory in field results, making it possible to measure crown porosity at different solar zenith angles. However, pruning fresh weight did not show any relationship with crown porosity due to the great differences between removed branches. A robust and accurate algorithm was selected for crown porosity measurements in traditional olive trees, making it possible to discern between different pruning treatments. PMID:27213391

  3. COMPARISON OF 24H AVERAGE VOC MONITORING RESULTS FOR RESIDENTIAL INDOOR AND OUTDOOR AIR USING CARBOPACK X-FILLED DIFFUSIVE SAMPLERS AND ACTIVE SAMPLING - A PILOT STUDY

    EPA Science Inventory

    Analytical results obtained by thermal desorption GC/MS for 24h diffusive sampling of 11 volatile organic compounds (VOCs) are compared with results of time-averaged active sampling at a known constant flow rate. Air samples were collected with co-located duplicate diffusive samp...

  4. Measurement of effective air diffusion coefficients for trichloroethene in undisturbed soil cores.

    PubMed

    Bartelt-Hunt, Shannon L; Smith, James A

    2002-06-01

    In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm2/s over a range of air-filled porosity of 0.23-0.49. The experimental data were compared to several previously published relations that predict diffusion coefficients as a function of air-filled porosity and porosity. A multiple linear regression analysis was developed to determine if a modification of the exponents in Millington's [Science 130 (1959) 100] relation would better fit the experimental data. The literature relations appeared to generally underpredict the effective diffusion coefficient for the soil cores studied in this work. Inclusion of a particle-size distribution parameter, d10, did not significantly improve the fit of the linear regression equation. The effective diffusion coefficient and porosity data were used to recalculate estimates of diffusive flux through the subsurface made in a previous study performed at the field site. It was determined that the method of calculation used in the previous study resulted in an underprediction of diffusive flux from the subsurface. We conclude that although Millington's [Science 130 (1959) 100] relation works well to predict effective diffusion coefficients in homogeneous soils with relatively uniform particle-size distributions, it may be inaccurate for many natural soils with heterogeneous structure and/or non-uniform particle-size distributions.

  5. Measurement of effective air diffusion coefficients for trichloroethene in undisturbed soil cores

    NASA Astrophysics Data System (ADS)

    Bartelt-Hunt, Shannon L.; Smith, James A.

    2002-06-01

    In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm 2/s over a range of air-filled porosity of 0.23-0.49. The experimental data were compared to several previously published relations that predict diffusion coefficients as a function of air-filled porosity and porosity. A multiple linear regression analysis was developed to determine if a modification of the exponents in Millington's [Science 130 (1959) 100] relation would better fit the experimental data. The literature relations appeared to generally underpredict the effective diffusion coefficient for the soil cores studied in this work. Inclusion of a particle-size distribution parameter, d10, did not significantly improve the fit of the linear regression equation. The effective diffusion coefficient and porosity data were used to recalculate estimates of diffusive flux through the subsurface made in a previous study performed at the field site. It was determined that the method of calculation used in the previous study resulted in an underprediction of diffusive flux from the subsurface. We conclude that although Millington's [Science 130 (1959) 100] relation works well to predict effective diffusion coefficients in homogeneous soils with relatively uniform particle-size distributions, it may be inaccurate for many natural soils with heterogeneous structure and/or non-uniform particle-size distributions.

  6. Evaluation of the Flush/Fill and High-Pressure Air Purge Procedures for Converting Army Vehicles to Silicone Brake Fluid.

    DTIC Science & Technology

    1982-02-01

    dispersed spray/ fog . 4 100 Acetylene 50 The initial spray was ignited by the torch Torch and burned until the fluid/air ratio be- came too low to support... burning . 5 150 None 40 A spray ot large droplets followed by a very finely dispersed spray/ fog . 6 150 Acetylene 40 The initial spray was ignited by...Results ! 50 None 60 Initially a spray of large droplets followed by a very fine mist/ fog . 2 50 Acetylene 60 The initial mist was ignited by the torch

  7. Modeling of the transition zone porosity

    SciTech Connect

    Bourdette, B.; Ringot, E.; Ollivier, J.P.

    1995-05-01

    The ion diffusion process in mortar is different from the one which occurs in cement paste. This difference is due to the presence of transition zones, which take place around the grains in mortar and which are very porous regions. Based on mercury intrusion porosimetry experimental data and on the analysis of percolation through a 3D mortar model, a computation of the transition zone porosity and of the bulk paste porosity has been carried out. The porosity of the transition zone has been analyzed as a function of the mortar composition and of the degree of hydration.

  8. Measurement of porosity in ceramic coatings by thermogravimetric volatilization of liquids

    SciTech Connect

    Craig, B.D.; Francis, L.F.; Abrams, L.

    1996-12-01

    A simple gravimetric method was developed to determine the open porosity in ceramic coatings. The coating`s pore space was filled with a liquid and the weight loss on volatilization of the liquid was measured in a thermogravimetric analyzer. This thermogravimetric volatilization of liquids (TVL) method was used to characterize the porosity in titania coatings, alumina/aluminum phosphate coatings, and free-standing films of alumina. Several liquids were used; ethylene glycol and 1,3-propanediol gave the best results due to their low volatilities at room temperature. The measured porosities of the ceramic coatings ranged from 30% to 80% and the pore sizes (as determined by SEM and mercury porosimetry) ranged from 0.1 to 15 {micro}m. The standard deviation of the TVL measurement was smaller for thicker coatings (e.g., {ge}20{micro}m). Porosities determined by TVL were within typically 5--10% of those determined by mercury intrusion porosimetry on identical samples. Characterization of a series of alumina/aluminum phosphate coatings showed a decrease in porosity consistent with expectations based on density and SEM observations. TVL is nondestructive, can be used for small volumes of sample, and when combined with SEM, provides a good means to characterize coating porosity and pore structure.

  9. Getting a prescription filled

    MedlinePlus

    ... prescription filled; Drugs - how to get prescription filled; Pharmacy - mail order; Pharmacy - internet; Types of pharmacies ... paper prescription that you take to a local pharmacy Calling or e-mailing a pharmacy to order ...

  10. Estimation of Concrete's Porosity by Ultrasounds

    NASA Astrophysics Data System (ADS)

    Benouis, A.; Grini, A.

    Durability of concrete depends strongly on porosity; this conditions the intensity of the interactions of the concrete with the aggressive agents. The pores inside the concrete facilitate the process of damage, which is generally initiated on the surface. The most used measurement is undoubtedly the measurement of porosity accessible to water. The porosimetry by intrusion with mercury constitutes a tool for investigation of the mesoporosity. The relationship between concrete mixtures, porosity and ultrasonic velocity of concrete samples measured by ultrasonic NDT is investigated. This experimental study is interested in the relations between the ultrasonic velocity measured by transducers of 7.5 mm and 49.5 mm diameter and with 54 kHz frequency. Concrete specimens (160 mm diameter and 320 mm height) are fabricated with concrete of seven different mixtures (various W/C and S/S + G ratios), which gave porosities varying between 7% and 16%. Ultrasonic velocities in concrete were measured in longitudinal direction. Finally the results showed the influence of ratio W/C, where the porosity of the concretes of a ratio W/C _0,5 have correctly estimated by ultrasonic velocity. The integration of the concretes of a lower ratio, in this relation, caused a great dispersion. Porosity estimation of concretes with a ratio W/C lower than 0,5 became specific to each ratio.

  11. Porosity prediction in sandstones using erosional unconformities

    SciTech Connect

    Shanmugam, G.

    1989-03-01

    Erosional unconformities of subaerial origin are created by tectonic uplifts and eustatic sea level fall. Most erosional unconformities developed on sandstones are planes of increased porosity because uplifted sandstones are exposed to undersaturated CO/sub 2/-charged meteoric waters that result in dissolution of unstable framework grains and cements. The chemical weathering of sandstones is intensified in humid regions by the heavy rainfall, soil zones, lush vegetation, and accompanying voluminous production of organic and inorganic acids. Erosional unconformities are considered hydrologically open systems because of abundant supply of fresh meteoric water and relatively unrestricted transport of dissolved constituents away from the site of dissolution, causing a net gain in porosity near unconformities. Thus, porosity in sandstones tends to increase toward overlying unconformities. Such porosity trends have been observed in hydrocarbon-bearing sandstone reservoirs in Alaska, Algeria, Australia, China, Libya, Netherlands, Norwegian North Sea, Norwegian Sea, and Texas. A common attribute of these reservoirs is that they were all subaerially exposed under heavy rainfall conditions. An empirical model has been developed for the Triassic and Jurassic sandstone reservoirs in the Norwegian North Sea on the basis of the observed relationship that shows an increase in porosity in these reservoirs with increasing proximity to the overlying base of Cretaceous unconformity. An important practical attribute of this model is that it allows for the prediction of porosity in the neighboring undrilled areas by recognizing the base of Cretaceous unconformity in seismic reflection profiles and by constructing subcrop maps.

  12. Porosity and mechanically optimized PLGA based in situ hardening systems.

    PubMed

    Schloegl, W; Marschall, V; Witting, M Y; Volkmer, E; Drosse, I; Leicht, U; Schieker, M; Wiggenhorn, M; Schaubhut, F; Zahler, S; Friess, W

    2012-11-01

    Goal of the present study was to develop and to characterize in situ-hardening, porous PLGA-based systems for their future application as bone grafting materials. Therefore, we investigated the precipitation behavior of formulations containing PLGA and a water-miscible solvent, DMSO, PEG 400, and NMP. To increase porosity, a pore forming agent (NaCMC) was added and to enhance mechanical properties of the system, an inorganic filler (α-TCP) was incorporated. The behavior upon contact with water and the influence of the prior addition of aqueous media on the morphology of the corresponding hardened implants were investigated. We proved cell-compatibility by live/dead assays for the hardened porous polymer/ceramic-composite scaffolds. The IsHS formulations can therefore be used to manufacture hardened scaffolds ex vivo by using molds with the desired shape and size. Cells were further successfully incorporated into the IsHS by precultivating the cells on the α-TCP-powder prior to their admixing to the formulation. However, cell viability could not be maintained due to toxicity of the tested solvents. But, the results demonstrate that in vivo cells should well penetrate, adhere, and proliferate in the hardened scaffolds. Consequently, we consider the in situ hardening system being an excellent candidate as a filling material for non-weight-bearing orthopedic indications, as the resulting properties of the hardened implant fulfill indication-specific needs like mechanical stability, elasticity, and porosity.

  13. Self-Assembling Sup-porosity: The Effect On Fluid Flow And Seismic Wave Propagation

    SciTech Connect

    Pyrak-Nolte, Laura J.

    2013-04-27

    Fractures and joints in the field often contain debris within the void spaces. Debris originates from many different mechanisms: organic and/or inorganic chemical reactions/mineralization, sediment transport, formation of a fracture, mechanical weathering or combinations of these processes. In many cases, the presence of debris forms a sub-porosity within the fracture void space. This sub-porosity often is composed of material that differs from the fracture walls in mineralogy and morphology. The sub-porosity may partially fill voids that are on the order of hundreds of microns and thereby reduce the local porosity to lengths scales on the order of sub-microns to tens of microns. It is quite clear that a sub-porosity affects fracture porosity, permeability and storativity. What is not known is how the existence/formation of a sub-porosity affects seismic wave propagation and consequently our ability to probe changes in the subsurface caused by the formation or alteration of a sub-porosity. If seismic techniques are to be developed to monitor the injection and containment of phases in sequestration reservoirs or the propping of hydraulically induced fracture to enhance oil & gas production, it is important to understand how a sub-porosity within a fracture affects macroscopic seismic and hydraulic measurements. A sub-porosity will directly affect the interrelationship between the seismic and hydraulic properties of a fracture. This reports contains the results of the three main topics of research that were performed (1) to determine the effect of a sub-porosity composed of spherical grains on seismic wave propagation across fractures, (2) to determine the effect of biofilm growth in pores and between grains on seismic wave propagation in sediment, and (3) to determine the effect of the scale of observation (field-of-view) on monitoring alteration the pore space within a fracture caused by reactive flow. A brief summary of the results for each topic is contained in

  14. SALTSTONE VARIABILITY STUDY - MEASUREMENT OF POROSITY

    SciTech Connect

    Harbour, J; Vickie Williams, V; Tommy Edwards, T; Russell Eibling, R; Ray Schumacher, R

    2007-08-23

    One of the goals of the Saltstone Variability Study is to identify the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. One of the key performance properties is porosity which is a measure of the volume percent of a cured grout that is occupied by salt solution (for the saturated case). This report presents (1) the results of efforts to develop a method for the measurement of porosity of grout samples and (2) initial results of porosity values for samples that have been previously produced as part of the Saltstone Variability Study. A cost effective measurement method for porosity was developed that provides reproducible results, is relatively fast (30 to 60 minutes per sample) and uses a Mettler Toledo HR83 Moisture Analyzer that is already operational and routinely calibrated at Aiken County Technology Laboratory. The method involves the heating of the sample at 105 C until no further mass loss is observed. This mass loss value, which is due to water evaporation, is then used to calculate the volume percent porosity of the mix. The results of mass loss for mixes at 105 C were equivalent to the results obtained using thermal gravimetric analysis. The method was validated by comparing measurements of mass loss at 105 C for cured portland cement in water mixes to values presented in the literature for this system. A stereopycnometer from Quantachrome Instruments was selected to measure the cured grout bulk densities. Density is a property that is required to calculate the porosities. A stereopycnometer was already operational at Aiken County Technology Laboratory, has been calibrated using a solid stainless steel sphere of known volume, is cost effective and fast ({approx}15 minutes per sample). Cured grout densities are important in their own right because they can be used to project the volume of waste form produced from a given amount of salt feed of known composition. For

  15. Simple and Inexpensive Method of Wood Pellets Macro-porosity Measurement

    SciTech Connect

    C. Igathinathane; Jaya Shankar Tumuluru; S. Sokhansanj; X. Bi; C. J. Lim; S. Melin; E. Mohammad

    2010-08-01

    A novel simplified stereometric measurement method for determining the macro-porosity of wood pellets through geometrical approach was successfully developed and tested. The irregular ends of pellets of circular cross-section were sanded flat so that their geometry becomes cylinder and their volumes evaluated using mensuration formula. Such formed cylindrical pellets were loose or tap filled to selected volumes to evaluate the macro-porosity and the constant specific weight. The method was extended to evaluate actual wood pellets properties. Overall macro-porosity of actual wood pellets was determined as 41.0±2.5% and 35.5±2.7%, mean bulk density as and , and classified as “Class-3:Medium” and “Class-3&4:Medium to Low” for loose and tapped fills, respectively. Hausner ratio and Carr’s compressibility index classify wood pellets as “freely flowing.” The developed stereometric method can be used as a handy inexpensive laboratory procedure to estimate the macro-porosity of different types and makes of wood pellets and other similar packaged materials.

  16. Simple and inexpensive method of wood pellets macro-porosity measurement

    SciTech Connect

    Igathinathane, C.; Tumuluru, J.S.; Sokhansanj, Shahabaddine; Bi, X.T.; Lim, C. Jim; Melin, Staffan; Mohammad, E.

    2010-01-01

    A novel simplified stereometric measurement method for determining the macro-porosity of wood pellets through geometrical approach was successfully developed and tested. The irregular ends of pellets of circular cross-section were sanded flat so that their geometry becomes cylinder and their volumes evaluated using mensuration formula. Such formed cylindrical pellets were loose or tap filled to selected volumes to evaluate the macro-porosity and the constant specific weight. The method was extended to evaluate actual wood pellets properties. Overall macro-porosity of actual wood pellets was determined as 41.0 2.5% and 35.5 2.7%, mean bulk density as and, and classified as Class-3:Medium and Class-3&4:Medium to Low for loose and tapped fills, respectively. Hausner ratio and Carr s compressibility index classify wood pellets as freely flowing. The developed stereometric method can be used as a handy inexpensive laboratory procedure to estimate the macro-porosity of different types and makes of wood pellets and other similar packaged materials.

  17. Simple and inexpensive method of wood pellets macro-porosity measurement.

    PubMed

    Igathinathane, C; Tumuluru, Jaya Shankar; Sokhansanj, S; Bi, X; Lim, C J; Melin, S; Mohammad, E

    2010-08-01

    A novel simplified stereometric measurement method for determining the macro-porosity of wood pellets through geometrical approach was successfully developed and tested. The irregular ends of pellets of circular cross-section were sanded flat so that their geometry becomes cylinder and their volumes evaluated using mensuration formula. Such formed cylindrical pellets were loose or tap filled to selected volumes to evaluate the macro-porosity and the constant specific weight. The method was extended to evaluate actual wood pellets properties. Overall macro-porosity of actual wood pellets was determined as 41.0+/-2.5% and 35.5+/-2.7%, mean bulk density as 670+/-29 kg m(-3) and 731+/-31 kg m(-3), and classified as "Class-3:Medium" and "Class-3&4:Medium to Low" for loose and tapped fills, respectively. Hausner ratio and Carr's compressibility index classify wood pellets as "freely flowing." The developed stereometric method can be used as a handy inexpensive laboratory procedure to estimate the macro-porosity of different types and makes of wood pellets and other similar packaged materials.

  18. High=porosity Cenozoic carbonate rocks of South Florida: progressive loss of porosity with depth

    USGS Publications Warehouse

    Halley, Robert B.; Schmoker, James W.

    1983-01-01

    Porosity measurements by borehole gravity meter in subsurface Cenozoic carbonates of South Florida reveal an extremely porous mass of limestone and dolomite which is transitional in total pore volume between typical porosity values for modern carbonate sediments and ancient carbonate rocks. A persistent decrease of porosity with depth, similar to that of chalks of the Gulf Coast, occurs in these rocks. Carbonate strata with less than 20% porosity are absent from the rocks studied here. Aquifers and aquicludes cannot be distinguished on the basis of porosity. Aquifers are not exceptionally porous when compared to other Tertiary carbonate rocks in South Florida. Permeability in these strata is governed more by the spacial distribution of pore space and matrix than by total volume of porosity present. Dolomite is as porous as, or slightly less porous than, limestones in these rocks. This observation places limits on any model proposed for dolomitization and suggests that dolomitization does not take place by a simple ion-for-ion replacement of magnesium for calcium. Dolomitization may be selective for less porous limestone, or it may involve the incorporation of significant amounts of carbonate as well as magnesium into the rock. The great volume of pore space in these rocks serves to highlight the inefficiency of early diagenesis in reducing carbonate porosity and to emphasize the importance of later porosity reduction which occurs during the burial or late near-surface history of limestones and dolomites.

  19. Graded-porosity heat-pipe wicks

    NASA Technical Reports Server (NTRS)

    Eninger, J. E.

    1976-01-01

    To maximize the capacity of a nonarterial heat pipe, a wick is considered whose porosity is allowed to vary axially along its length. At every axial location the porosity is set no lower than required to maintain the wick in a nearly saturated state under the maximum heat-transport rate. The result is a wick whose permeability is everywhere as high as possible. The differential equation that governs the optimum porosity variation is solved numerically between a condenser-end boundary condition that just prevents a liquid slug or puddle in the vapor spaces and an evaporator-end boundary condition that just prevents circumferential groove dry-up. Experimental performance measurements for an ammonia heat pipe are presented.

  20. Permeability-porosity relationships in sedimentary rocks

    USGS Publications Warehouse

    Nelson, Philip H.

    1994-01-01

    In many consolidated sandstone and carbonate formations, plots of core data show that the logarithm of permeability (k) is often linearly proportional to porosity (??). The slope, intercept, and degree of scatter of these log(k)-?? trends vary from formation to formation, and these variations are attributed to differences in initial grain size and sorting, diagenetic history, and compaction history. In unconsolidated sands, better sorting systematically increases both permeability and porosity. In sands and sandstones, an increase in gravel and coarse grain size content causes k to increase even while decreasing ??. Diagenetic minerals in the pore space of sandstones, such as cement and some clay types, tend to decrease log(k) proportionately as ?? decreases. Models to predict permeability from porosity and other measurable rock parameters fall into three classes based on either grain, surface area, or pore dimension considerations. (Models that directly incorporate well log measurements but have no particular theoretical underpinnings from a fourth class.) Grain-based models show permeability proportional to the square of grain size times porosity raised to (roughly) the fifth power, with grain sorting as an additional parameter. Surface-area models show permeability proportional to the inverse square of pore surface area times porosity raised to (roughly) the fourth power; measures of surface area include irreducible water saturation and nuclear magnetic resonance. Pore-dimension models show permeability proportional to the square of a pore dimension times porosity raised to a power of (roughly) two and produce curves of constant pore size that transgress the linear data trends on a log(k)-?? plot. The pore dimension is obtained from mercury injection measurements and is interpreted as the pore opening size of some interconnected fraction of the pore system. The linear log(k)-?? data trends cut the curves of constant pore size from the pore-dimension models

  1. Effect of the features of functionalized structure on elastic properties and strength of partially-filled brittle porous materials

    NASA Astrophysics Data System (ADS)

    Konovalenko, Igor S.; Shilko, Evgeny V.; Konovalenko, Ivan S.; Vodopjyanov, Egor M.

    2016-11-01

    A two-scale mechanical model of brittle porous material partially filled with plastic filler (inclusions) was developed within the framework of the formalism of movable cellular automaton method. The model was applied to study the mechanical properties of mesoscopic samples with a linear distribution of the local porosity in the depth of the material. Calculation results showed essentially nonlinear dependence of their elastic and strength properties on the degree of pore space filling. It is found that depending on the sign of the gradient of porosity the value of shear strength of partially filled samples can significantly increase or remain constant with increase in the value of the degree of filling.

  2. Gas phase dispersion in compost as a function of different water contents and air flow rates.

    PubMed

    Sharma, Prabhakar; Poulsen, Tjalfe G

    2009-07-21

    Gas phase dispersion in a natural porous medium (yard waste compost) was investigated as a function of gas flow velocity and compost volumetric water content using oxygen and nitrogen as tracer gases. The compost was chosen because it has a very wide water content range and because it represents a wide range of porous media, including soils and biofilter media. Column breakthrough curves for oxygen and nitrogen were measured at relatively low pore gas velocities, corresponding to those observed in for instance soil vapor extraction systems or biofilters for air cleaning at biogas plants or composting facilities. Total gas mechanical dispersion-molecular diffusion coefficients were fitted from the breakthrough curves using a one-dimensional numerical solution to the advection-dispersion equation and used to determine gas dispersivities at different volumetric gas contents. The results showed that gas mechanical dispersion dominated over molecular diffusion with mechanical dispersion for all water contents and pore gas velocities investigated. Importance of mechanical dispersion increased with increasing pore gas velocity and compost water content. The results further showed that gas dispersivity was relatively constant at high values of compost gas-filled porosity but increased with decreasing gas-filled porosity at lower values of gas-filled porosity. Results finally showed that measurement uncertainty in gas dispersivity is generally highest at low values of pore gas velocity.

  3. Study of electro-osmotic flows in microchannels packed with variable porosity media via lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Chai, Zhenhua; Guo, Zhaoli; Shi, Baochang

    2007-05-01

    In this article, electro-osmotic flow (EOF) in microchannels packed with a variable porosity medium is studied using the lattice Boltzmann method (LBM). The present lattice Boltzmann model is constructed based on the generalized porous medium equation for EOF and validated by comparing the numerical solution with the approximate analytical solution. A detailed parametric study has been presented for EOF in microchannels filled with a variable porosity medium. It is found that the variations of porosity, particle size, ζ potential, applied electric field strength, and tortuosity significantly affect the flow pattern. Numerical results also indicate that the variation of the porosity near the wall has an important influence on the velocity profile, and should not be neglected in practice.

  4. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, G.C.; Brinker, C.J.; Doughty, D.H.; Bein, T.; Moller, K.

    1993-07-06

    Coatings and sensors are described having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

  5. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, Gregory C.; Brinker, C. Jeffrey; Doughty, Daniel H.; Bein, Thomas; Moller, Karin

    1993-01-01

    Coatings and sensors having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

  6. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, Gregory C.; Brinker, C. Jeffrey; Doughty, Daniel H.; Bein, Thomas; Moller, Karin

    1996-01-01

    Coatings and sensors having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

  7. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, G.C.; Brinker, C.J.; Doughty, D.H.; Bein, T.; Moller, K.

    1996-12-31

    Coatings and sensors are disclosed having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided. 7 figs.

  8. Formulas for sediment porosity and settling velocity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The formulas of Komura (1963) and Han et al. (1981) for the initial porosity of sediment deposits were tested using data sets collected in different countries and regions. It was found that Komura’s formula slightly underestimates the dry density for sand and gravel deposits and overestimates those ...

  9. Porosity Log Prediction Using Artificial Neural Network

    NASA Astrophysics Data System (ADS)

    Dwi Saputro, Oki; Lazuardi Maulana, Zulfikar; Dzar Eljabbar Latief, Fourier

    2016-08-01

    Well logging is important in oil and gas exploration. Many physical parameters of reservoir is derived from well logging measurement. Geophysicists often use well logging to obtain reservoir properties such as porosity, water saturation and permeability. Most of the time, the measurement of the reservoir properties are considered expensive. One of method to substitute the measurement is by conducting a prediction using artificial neural network. In this paper, artificial neural network is performed to predict porosity log data from other log data. Three well from ‘yy’ field are used to conduct the prediction experiment. The log data are sonic, gamma ray, and porosity log. One of three well is used as training data for the artificial neural network which employ the Levenberg-Marquardt Backpropagation algorithm. Through several trials, we devise that the most optimal input training is sonic log data and gamma ray log data with 10 hidden layer. The prediction result in well 1 has correlation of 0.92 and mean squared error of 5.67 x10-4. Trained network apply to other well data. The result show that correlation in well 2 and well 3 is 0.872 and 0.9077 respectively. Mean squared error in well 2 and well 3 is 11 x 10-4 and 9.539 x 10-4. From the result we can conclude that sonic log and gamma ray log could be good combination for predicting porosity with neural network.

  10. A simple procedure for estimating soil porosity

    NASA Astrophysics Data System (ADS)

    Emmet-Booth, Jeremy; Forristal, Dermot; Fenton, Owen; Holden, Nick

    2016-04-01

    Soil degradation from mismanagement is of international concern. Simple, accessible tools for rapidly assessing impacts of soil management are required. Soil structure is a key component of soil quality and porosity is a useful indicator of structure. We outline a version of a procedure described by Piwowarczyk et al. (2011) used to estimate porosity of samples taken during a soil quality survey of 38 sites across Ireland as part of the Government funded SQUARE (Soil Quality Assessment Research) project. This required intact core (r = 2.5 cm, H = 5cm) samples taken at 5-10 cm and 10-20 cm depth, to be covered with muslin cloth at one end and secured with a jubilee clip. Samples were saturated in sealable water tanks for ≈ 64 hours, then allowed to drain by gravity for 24 hours, at which point Field Capacity (F.C.) was assumed to have been reached, followed by oven drying with weight determined at each stage. This allowed the calculation of bulk density and the estimation of water content at saturation and following gravitational drainage, thus total and functional porosity. The assumption that F.C. was reached following 24 hours of gravitational drainage was based on the Soil Moisture Deficit model used in Ireland to predict when soils are potentially vulnerable to structural damage and used nationally as a management tool. Preliminary results indicate moderately strong, negative correlations between estimated total porosity at 5-10 cm and 10-20 cm depth (rs = -0.7, P < 0.01 in both cases) and soil quality scores of the Visual Evaluation of Soil Structure (VESS) method which was conducted at each survey site. Estimated functional porosity at 5-10 cm depth was found to moderately, negatively correlate with VESS scores (rs = - 0.5, P < 0.05). This simple procedure requires inexpensive equipment and appears useful in indicating porosity of a large quantity of samples taken at numerous sites or if done periodically, temporal changes in porosity at a field scale

  11. Porosity evolution in Icelandic hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Thien, B.; Kosakowski, G.; Kulik, D. A.

    2014-12-01

    Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced hydrothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems, grant number CRSII2_141843/1) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. These are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. These shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. Field observations suggest that active and fossil Icelandic hydrothermal systems are built from a superposition of completely altered and completely unaltered layers. With help of 1D and 2D reactive transport models (OpenGeoSys-GEM code), we investigate the reasons for this finding, by studying the mineralogical evolution of protoliths with different initial porosities at different temperatures and pressures, different leaching water composition and gas content, and different porosity geometries (i.e. porous medium versus fractured medium). From this study, we believe that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are key factors to explain the different alteration extents observed in field studies. We also discuss how precipitation and dissolution kinetics can influence the alteration time scales.

  12. Film fill for power plant cooling towers

    SciTech Connect

    Mirsky, G.R. ); Monjoie, M. )

    1991-01-01

    This paper reports on film fill, which is the use of flat or formed sheets to provide a surface upon which liquid and air come in contact with each other to affect the exchange of heat. The only other fill options available to a cooling tower designer is the use of splash fill or combinations whereby heat exchange occurs on the surface of water droplets, or both. As film fill allows the designer the opportunity to build a more compact, cost effective, energy efficient cooling tower; this type of fill material is receiving ever increasing acceptance and finding it way into more and more cooling tower applications. film fill is used to both counterflow and crossflow cooling towers, from small air conditioning applications to large natural draft towers serving 1300 to 1500 M.W. power plants around the world. It is being used in applications using unfiltered water high in suspended solids, high concentrations of dissolved salts, water carrying fibers, silt, mud, treated and untreated waste effluent, scale etc. These situations are caused by users who are: trying to reduce water make-up, using untreated or unfiltered water, or trying to save on the cost of chemical treatment.

  13. Porosity Dependence of Piezoelectric Properties for Porous Potassium Niobate System Ceramics

    NASA Astrophysics Data System (ADS)

    Wada, S.; Mase, Y.; Shimizu, S.; Maeda, K.; Fujii, I.; Nakashima, K.; Pulpan, P.; Miyajima, N.

    2011-10-01

    Porous potassium niobate (KNbO3, KN) system ceramics were prepared by a conventional sintering method using carbon black (CB) nanoparticles. First, KN nanoparticles with a size of 100 nm was mixed with CB nanoparticles and binder using ball milling with ethanol. The mixture was dried, and pressed into pellets using uniaxial pressing. After binder burnout, these ceramics was sintered in air. Their piezoelectric properties were measured and discussed a relationship between porosity and piezoelectric properties. As the results, with increasing porosity, piezoelectric g33 constant increased significantly, which suggested that porous ceramics were effective for stress sensor application.

  14. Porosity and the ecology of icy satellites

    NASA Technical Reports Server (NTRS)

    Croft, Steven K.

    1993-01-01

    The case for a significant role for porosity in the structure and evolution of icy bodies in the Solar System has been difficult to establish. We present a relevant new data set and a series of structure models including a mechanical compression, not thermal creep, model for porosity that accounts satisfactorily for observed densities, moments of inertia, geologic activity, and sizes of tectonic features on icy satellites. Several types of observational data sets have been used to infer significant porosity, but until recently, alternative explanations have been preferred. Our first area of concern is the occurrence of cryovolcanism as a function of satellite radius; simple radiogenic heating models of icy satellites suggest minimum radii for melting and surface cryovolcanism to be 400 to 500 km, yet inferred melt deposits are seen on satellites half that size. One possible explanation is a deep, low conductivity regolith which lowers conductivity and raises internal temperatures, but other possibilities include tidal heating or crustal compositions of low conductivity. Our second area of concern is the occurrence and magnitude of tectonic strain; tectonic structures have been seen on icy satellites as small as Mimas and Proteus. The structures are almost exclusively extensional, with only a few possible compression Al features, and inferred global strains are on the order of 1 percent expansion. Expansions of this order in small bodies like Mimas and prevention of late compressional tectonics due to formation of ice mantles in larger bodies like Rhea are attained only in structure models including low-conductivity, and thus possibly high porosity, crusts. Thirdly, inferred moments of inertia less than 0.4 in Mimas and Tethys can be explained by high-porosity crusts, but also by differentiation of a high density core. Finally, the relatively low densities of smaller satellites like Mimas and Miranda relative to larger neighbors can be explained by deep porosity

  15. Petrologic and petrophysical evaluation of the Dallas Center Structure, Iowa, for compressed air energy storage in the Mount Simon Sandstone.

    SciTech Connect

    Heath, Jason E.; Bauer, Stephen J.; Broome, Scott Thomas; Dewers, Thomas A.; Rodriguez, Mark A

    2013-03-01

    The Iowa Stored Energy Plant Agency selected a geologic structure at Dallas Center, Iowa, for evaluation of subsurface compressed air energy storage. The site was rejected due to lower-than-expected and heterogeneous permeability of the target reservoir, lower-than-desired porosity, and small reservoir volume. In an initial feasibility study, permeability and porosity distributions of flow units for the nearby Redfield gas storage field were applied as analogue values for numerical modeling of the Dallas Center Structure. These reservoir data, coupled with an optimistic reservoir volume, produced favorable results. However, it was determined that the Dallas Center Structure cannot be simplified to four zones of high, uniform permeabilities. Updated modeling using field and core data for the site provided unfavorable results for air fill-up. This report presents Sandia National Laboratories petrologic and petrophysical analysis of the Dallas Center Structure that aids in understanding why the site was not suitable for gas storage.

  16. Attempts to Produce D2-Gas-Filled Be Shells

    SciTech Connect

    Cook, B; McElfresh, M; Alford, C; Fought, E; Letts, S

    2005-01-14

    We have attempted to fabricate some 0.5 mm diameter D{sub 2}-gas-filled Be shells by coating gas-filled PVA-coated GDP mandrels with Cu-doped Be. We find that during the coating all (or most) of the gas leaks out. This is likely due to either small cracks or holes in the coating that are formed at the earliest points and are maintained during the thickness build-up of the coating, and/or to some level of intrinsic porosity in the coating. This memo documents our efforts.

  17. Primary porosity and submarine diagenesis in Lower Cretaceous Coral-Rudist reefs

    SciTech Connect

    Cross, S.L.; Lighty, R.G.

    1986-05-01

    Coral-rudist reefs of the Lower Cretaceous Mural limestone, southeastern Arizona, show a pronounced relationship between specific reef facies, primary porosity, and early submarine diagenesis. These large open-shelf reefs differ from the well-studied low-relief rudist buildups, and provide an alternate analog for many Cretaceous reef reservoirs. Arizona buildups have diverse corals, high depositional relief, and a well-developed facies zonation from fore reef to back reef: skeletal grainstone talus, muddy fore reef with branching and lamellar corals, massive reef crest with abundant lamellar corals and sandy matrix, protected thickets of delicate branching corals and large rudist mounds, and a wide sediment apron of well-washed coral, rudist, and benthic foraminiferal sands. These well-exposed outcrops permit a detailed facies comparison of primary interparticle porosity. Porosity as high as 40% in grainstones was occluded by later subsurface cements. Reef-framework interparticle porosity was negligible because fore-reef coral and back-reef rudist facies were infilled by muds, and high-energy reef-crest frameworks were filled by peloidal submarine cement crusts and muddy skeletal sands. These thick crusts coated lamellar corals in cryptic and open reef-crest areas, and are laminated with ripple and draped bed forms that suggest current influence. Similar peloidal crusts and laminated textures are common magnesium-calcite submarine cement features in modern reefs. By documenting specific facies control on early cementation and textural variability, patterns of late-stage subsurface diagenesis and secondary porosity may be more easily explained for Cretaceous reef reservoirs. Significant primary porosity might be retained between sands in back-reef facies and within coral skeletons.

  18. Dolomite reservoirs: Porosity evolution and reservoir characteristics

    SciTech Connect

    Sun, S.Q.

    1995-02-01

    Systematic analyses of the published record of dolomite reservoirs worldwide reveal that the majority of hydrocarbon-producing dolomite reservoirs occurs in (1) peritidal-dominated carbonate, (2) subtidal carbonate associated with evaporitic tidal flat/lagoon, (3) subtidal carbonate associated with basinal evaporite, and (4) nonevaporitic carbonate sequence associated with topographic high/unconformity, platform-margin buildup or fault/fracture. Reservoir characteristics vary greatly from one dolomite type to another depending upon the original sediment fabric, the mechanism by which dolomite was formed, and the extent to which early formed dolomite was modified by post-dolomitization diagenetic processes (e.g., karstification, fracturing, and burial corrosion). This paper discusses the origin of dolomite porosity and demonstrates the porosity evolution and reservoir characteristics of different dolomite types.

  19. Correlation of Water Frost Porosity in Laminar Flow over Flat Surfaces

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2011-01-01

    A dimensionless correlation has been proposed for water frost porosity expressing its dependence on frost surface temperature and Reynolds number for laminar forced flow over a flat surface. The correlation is presented in terms of a dimensionless frost surface temperature scaled with the cold plate temperature, and the freezing temperature. The flow Reynolds number is scaled with reference to the critical Reynolds number for laminar-turbulent transition. The proposed correlation agrees satisfactorily with the simultaneous measurements of frost density and frost surface temperature covering a range of plate temperature, ambient air velocity, humidity, and temperature. It is revealed that the frost porosity depends primarily on the frost surface and the plate temperatures and the flow Reynolds number, and is only weakly dependent on the relative humidity. The results also point out the general character of frost porosity displaying a decrease with an increase in flow Reynolds number.

  20. Reducing the open porosity of pyroboroncarbon articles

    NASA Astrophysics Data System (ADS)

    Martyushov, G. G.; Zakharevich, A. M.; Pichkhidze, S. Ya.; Koshuro, V. A.

    2016-02-01

    It is established that a decrease in the open porosity of pyroboroncarbon, a pyrolytic glassy composite material of interest for manufacturing prosthetic heart valves (PHVs), can be achieved via impregnation of articles with an alcohol solution of 3-aminopropyltriethoxysilane and subsequent thermal treatment. The maximum roughness height and linear size of open pores on the surface of PHV parts made of pyroboroncarbon can additionally be reduced by final mechanical processing of a silicon oxide film formed on the surface.

  1. Effect of quartz overgrowth precipitation on the multiscale porosity of sandstone: A (U)SANS and imaging analysis

    SciTech Connect

    Anovitz, Lawrence M.; Cole, David R.; Jackson, Andrew J.; Rother, Gernot; Littrell, Kenneth C.; Allard, Lawrence F.; Pollington, Anthony D.; Wesolowski, David J.

    2015-06-01

    We have performed a series of experiments to understand the effects of quartz overgrowths on nanometer to centimeter scale pore structures of sandstones. Blocks from two samples of St. Peter Sandstone with different initial porosities (5.8 and 18.3%) were reacted from 3 days to 7.5 months at 100 and 200 °C in aqueous solutions supersaturated with respect to quartz by reaction with amorphous silica. Porosity in the resultant samples was analyzed using small and ultrasmall angle neutron scattering and scanning electron microscope/backscattered electron (SEM/BSE)-based image-scale processing techniques.Significant changes were observed in the multiscale pore structures. By three days much of the overgrowth in the low-porosity sample dissolved away. The reason for this is uncertain, but the overgrowths can be clearly distinguished from the original core grains in the BSE images. At longer times the larger pores are observed to fill with plate-like precipitates. As with the unreacted sandstones, porosity is a step function of size. Grain boundaries are typically fractal, but no evidence of mass fractal or fuzzy interface behavior was observed suggesting a structural difference between chemical and clastic sediments. After the initial loss of the overgrowths, image scale porosity (>~1 cm) decreases with time. Submicron porosity (typically ~25% of the total) is relatively constant or slightly decreasing in absolute terms, but the percent change is significant. Fractal dimensions decrease at larger scales, and increase at smaller scales with increased precipitation.

  2. Magnetic resonance imaging assessed cortical porosity is highly correlated with μCT porosity.

    PubMed

    Bae, Won C; Patil, Shantanu; Biswas, Reni; Li, Shihong; Chang, Eric Y; Statum, Sheronda; D'Lima, Darryl D; Chung, Christine B; Du, Jiang

    2014-09-01

    Cortical bone is typically regarded as "MR invisible" with conventional clinical magnetic resonance imaging (MRI) pulse sequences. However, recent studies have demonstrated that free water in the microscopic pores of cortical bone has a short T2* but a relatively long T2, and may be detectable with conventional clinical spin echo (SE) or fast spin echo (FSE) sequences. In this study we describe the use of a conventional two-dimensional (2D) FSE sequence to assess cortical bone microstructure and measure cortical porosity using a clinical 3T scanner. Twelve cadaveric human cortical bone samples were studied with MRI and microcomputed tomography (μCT) (downsampled to the same spatial resolution). Preliminary results show that FSE-determined porosity is highly correlated (R(2)=0.83; P<0.0001) with μCT porosity. Bland-Altman analysis suggested a good agreement between FSE and μCT with tight limit of agreement at around 3%. There is also a small bias of -2% for the FSE data, which suggested that the FSE approach slightly underestimated μCT porosity. The results demonstrate that cortical porosity can be directly assessed using conventional clinical FSE sequences. The clinical feasibility of this approach was also demonstrated on six healthy volunteers using 2D FSE sequences as well as 2D ultrashort echo time (UTE) sequences with a minimal echo time (TE) of 8μs, which provide high contrast imaging of cortical bone in vivo.

  3. Building 930, oblique view to southeast from fill slope covering ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Building 930, oblique view to southeast from fill slope covering building 932, 135 mm lens. - Travis Air Force Base, Snack Bar, North of W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

  4. Electrode porosity and effective electrocatalyst activity in electrode-membrane-assemblies (MEAs) of PEMFCs

    SciTech Connect

    Fischer, A.; Wendt, H.

    1996-12-31

    New production technologies of membrane-electrode-assemblies for PEWCs which ensure almost complete catalyst utilization by {open_quotes}wetting{close_quotes} the internal catalyst surface with the ionomeric electrolyte, allow for a reduction of Pt-loadings from prior 4 mg cm{sup -2} to now less than 0.5 mg cm{sup -2}. Such electrodes are not thicker than from 5 to 10 {mu}m. Little has been published hitherto about the detailed micromorphology of such electrodes and the role of electrode porosity on electrode performance. It is well known, that the porosity of thicker fuel cell electrodes, e.g. of PAFC or AFC electrodes is decisive for their performance. Therefore the issue of this investigation is to measure and to modify the porosity of electrodes prepared by typical MEA production procedures and to investigate the influence of this porosity on the effective catalyst activity for cathodic reduction of oxygen from air in membrane cells. It may be anticipated that any mass transfer hindrance of gaseous reactants into porous electrodes would manifest itself rather in the conversion of dilute gases than in the conversion of pure gases (e.g. neat oxygen). Therefore in this investigation the performance of membrane cell cathodes with non pressurized air had been compared to that with neat oxygen at cathodes which had a relatively low Pt-loading of 0.15 mg cm{sup -2}.

  5. Longhi Games, Internal Reservoirs, and Cumulate Porosity

    NASA Astrophysics Data System (ADS)

    Morse, S. A.

    2009-05-01

    Fe in plagioclase at an early age, T-rollers (or not) on the Di-Trid boundary in Fo-Di-Sil, the mantle solidus, origins of anorthosites, esoteric uses of Schreinemakers rules and many more topics are all fresh and pleasant memories of John Longhi's prolific and creative work. The Fram-Longhi experimental effect of pressure on plagioclase partitioning with liquid in mafic rocks became essential to an understanding of multiphase Rayleigh fractionation of plagioclase in big layered intrusions. Only by using the pressure effect could I find a good equation through the data for the Kiglapait intrusion, and that result among others required the existence with probability 1.0 of an internal reservoir (Morse, JPet 2008). Knowledge of cumulate porosity is a crucial key to the understanding of layered igneous rocks. We seek both the initial (inverse packing fraction) and residual porosity to find the time and process path from sedimentation to solidification. In the Kiglapait Lower Zone we have a robust estimate of mean residual porosity from the modes of the excluded phases augite, oxides, sulfide, and apatite. To this we apply the maximum variance of plagioclase composition (the An range) to find an algorithm that extends through the Upper Zone and to other intrusions. Of great importance is that all these measurements were made in grain mounts concentrated from typically about 200 g of core or hand specimen, hence the represented sample volume is thousands of times greater than for a thin section. The resulting distribution and scatter of the An range is novel and remarkable. It is V-shaped in the logarithmic representation of stratigraphic height, running from about 20 mole % at both ends (base to top of the Layered Series) to near-zero at 99 PCS. The intercept of the porosity-An range relation gives An range = 3.5 % at zero residual porosity. Petrographic analysis reveals that for PCS less than 95 and greater than 99.9, the An range is intrinsic, i.e. pre-cumulus, for

  6. Loose-fill insulations

    SciTech Connect

    1995-05-01

    Whether you are increasing the insulation levels in your current home or selecting insulation for a new home, choosing the right insulation material can be challenging. Fibrous loose-fill insulations such as cellulose, fiberglass, and rock wool are options you may wish to consider. This publication will introduce you to these materials--what they are, how they are applied, how they compare with each other, and other considerations regarding their use--so that you can decide whether loose fills are right for your home.

  7. Porosity enhancements at unconformities and their implications

    SciTech Connect

    Ghosh, S.K.

    1996-08-01

    Subaerial unconformities, common worldwide, are created by eustatic sea level fall or tectonic uplift. The increased porosities in sandstones at unconformities result from the dissolution of unstable grains like feldspar, lithic fragments and carbonate/sulphate cements by undersaturated carbon dioxide-rich meteoric waters. Even quartz and chert may dissolve, as observed in the Romima tepuys in Venezuela. Dissolution is pronounced in the coarsest, best sorted and permeable sandstones. Other porosity-controlling factors are mineralogy, grain size, nature and extent of initial diagenesis, duration of subaerial exposure, and timing of hydrocarbon migration. A common attribute of these unconformity-related reservoirs is that they were subaerially exposed in a humid, warm setting, characterized by copious rainfall. In the Maracaibo Basin, various northwest-south-east-trending fault-bounded reservoirs in the Eocene fluvio-deltaic Misoa Formation exhibit a systematic trend of diagenetic evolution related to the post-Eocene uplift (SB-39.5). The fault-bounded reservoirs are truncated by the erosional SB-39.5 unconformity. Both porosity and permeability show maximum values (24% and 2000 md) near the truncated erosional edge. The minimum values (12% and 50 md) occur furthest from the unconformity subcrop in areas beyond the influence of undersaturated waters. Additionally, from the subcrop edge saturated meteoric waters percolate downdip, and mix with deeper connate water and precipitated cements in the southeast, further reducing reservoir quality. In-depth exploration of unconformity related plays will yield significant dividends but it would require integrated analysis of depositional facies, petrology, diagenesis, and burial history, in relation to timing of hydrocarbon migration and structural development.

  8. Modeling of porosity formation and feeding flow during casting of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Lin, Zhiping

    Porosity is one of the most important defects in metal casting. To quantitatively predict the porosity formation during casting two numerical models are developed for steel and aluminum alloys respectively. For steel, a multi-phase model is developed that predicts melt pressure, feeding flow, porosity (both microscopic and macroscopic), and riser pipe formation during casting. The phases included in the model are solid, liquid, porosity, and air. An energy equation is solved to determine solid fraction. A multi-phase momentum equation, which is valid everywhere in the solution domain, is derived. A pressure equation is then derived from this momentum equation and a mixture continuity equation developed that accounts for all phases. The partial pressure of a gas species dissolved in the melt is determined using the species concentration, which is found by solving a species conservation equation that accounts for convection. Porosity forms once the gas pressure exceeds the sum of the melt pressure and the capillary pressure. The amount of porosity that forms is determined from the mixture continuity equation. The riser pipe is determined from an air continuity equation. A pore size model, which considers the effects of the solidifying steel microstructure on pore size, is incorporated into the multi-phase model. The multi-phase model is applied to one-dimensional, two-dimensional, and three-dimensional simulations. The results clearly illustrate the basic physical phenomena involved and predict microporosity and macroporosity distributions, as well as a riser pipe. For aluminum alloys a gas microsegregation model is developed to quantitatively predict porosity, coupled with the calculations of the pressure field, feeding flow, and distribution of dissolved gas species throughout the casting. The effects of dendritic and eutectic microstructure on the pore shape and size are considered in a pore size model. The model is applied to one-dimensional simulations of A319

  9. Determination of effective porosity of mudrocks: a feasibility study

    SciTech Connect

    Dorsch, J.

    1995-11-01

    Matrix diffusion is believed to be an important transport process within the double-porosity (primary sedimentary porosity and secondary fracture porosity) mudrock-dominated stratigraphic units on the Oak Ridge Reservation (ORR). Effective porosity is identified as an important parameter for evaluating and modeling matrix diffusion as a transport process. This report identifies, summarizes and evaluates petrophysical techniques, which can be used to determine the effective porosity of mudrock. Most of the techniques found their original application in the petroleum industry for the evaluation of reservoir rocks.

  10. Results from a new Cocks-Ashby style porosity model

    NASA Astrophysics Data System (ADS)

    Barton, Nathan

    2017-01-01

    A new porosity evolution model is described, along with preliminary results. The formulation makes use of a Cocks-Ashby style treatment of porosity kinetics that includes rate dependent flow in the mechanics of porosity growth. The porosity model is implemented in a framework that allows for a variety of strength models to be used for the matrix material, including ones with significant changes in rate sensitivity as a function of strain rate. Results of the effect of changing strain rate sensitivity on porosity evolution are shown. The overall constitutive model update involves the coupled solution of a system of nonlinear equations.

  11. Porosity and mechanical properties of zirconium ceramics

    SciTech Connect

    Kalatur, Ekaterina Narikovich, Anton; Buyakova, Svetlana E-mail: kulkov@ispms.tsc.ru; Kulkov, Sergey E-mail: kulkov@ispms.tsc.ru

    2014-11-14

    The article studies the porous ceramics consisting of ultra-fine ZrO{sub 2} powders. The porosity of ceramic samples varied from 15% to 80%. The structure of the ceramic materials had a cellular configuration. The distinctive feature of all experimentally obtained strain diagrams is their nonlinearity at low deformations characterized by the parabolic law. It was shown that the observed nonlinear elasticity for low deformations shown in strain diagrams is due to the mechanical instability of cellular elements of the ceramic framework.

  12. Porosity of additive manufacturing parts for process monitoring

    SciTech Connect

    Slotwinski, J. A.; Garboczi, E. J.

    2014-02-18

    Some metal additive manufacturing processes can produce parts with internal porosity, either intentionally (with careful selection of the process parameters) or unintentionally (if the process is not well-controlled.) Material porosity is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants, since surface-breaking pores allow for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the process. We are developing an ultrasonic sensor for detecting changes in porosity in metal parts during fabrication on a metal powder bed fusion system, for use as a process monitor. This paper will describe our work to develop an ultrasonic-based sensor for monitoring part porosity during an additive build, including background theory, the development and detailed characterization of reference additive porosity samples, and a potential design for in-situ implementation.

  13. Porosity, permeability, and their relationship in granite, basalt, and tuff

    SciTech Connect

    Not Available

    1983-04-01

    This report discusses the porosity, storage, and permeability of fractured (mainly crystalline) rock types proposed as host rock for nuclear waste repositories. The emphasis is on the inter-relationships of these properties, but a number of reported measurements are included as well. The porosity of rock is shown to consist of fracture porosity and matrix porosity; techniques are described for determining the total interconnected porosity through both laboratory and field measurement. Permeability coefficient, as obtained by experiments ranging from laboratory to crustal scale, is discussed. Finally, the problem of determining the relationship between porosity and permeability is discussed. There is no simple, all encompassing relationship that describes the dependence of permeability upon porosity. However, two particular cases have been successfully analyzed: flow through a single rough fracture, and flow through isotropic porous rock. These two cases are discussed in this report.

  14. Porosity of additive manufacturing parts for process monitoring

    NASA Astrophysics Data System (ADS)

    Slotwinski, J. A.; Garboczi, E. J.

    2014-02-01

    Some metal additive manufacturing processes can produce parts with internal porosity, either intentionally (with careful selection of the process parameters) or unintentionally (if the process is not well-controlled.) Material porosity is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants, since surface-breaking pores allow for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the process. We are developing an ultrasonic sensor for detecting changes in porosity in metal parts during fabrication on a metal powder bed fusion system, for use as a process monitor. This paper will describe our work to develop an ultrasonic-based sensor for monitoring part porosity during an additive build, including background theory, the development and detailed characterization of reference additive porosity samples, and a potential design for in-situ implementation.

  15. Air emissions from exposed contaminated sediments and dredged material

    SciTech Connect

    Valsaraj, K.T.; Ravikrishna, R.; Reible, D.D.; Thibodeaux, L.J.; Choy, B.; Price, C.B.; Brannon, J.M.; Myers, T.E.; Yost, S.

    1999-01-01

    The sediment-to-air fluxes of two polycyclic aromatic hydrocarbons (phenanthrene and pyrene) and a heterocyclic aromatic hydrocarbon (dibenzofuran) from a laboratory-contaminated sediment and those of three polycyclic aromatic hydrocarbons (naphthalene, phenanthrene, and pyrene) from three field sediments were investigated in experimental microcosms. The flux was dependent on the sediment moisture content, air-filled porosity, and the relative humidity of the air flowing over the sediment surface. The mathematical model predictions of flux from the laboratory-spiked sediment agreed with observed values. The fluxes of compounds with higher hydrophobicity were more air-side resistance controlled. Conspicuous differences were observed between the fluxes from the laboratory-spiked and two of the three field sediments. Two field sediments showed dramatic increases in mass-transfer resistances with increasing exposure time and had significant fractions of oil and grease. The proposed mathematical model was inadequate for predicting the flux from the latter field sediments. Sediment reworking enhanced the fluxes from the field sediments due to exposure of fresh solids to the air. Variations in flux from the lab-spiked sediment as a result of change in air relative humidity were due to differences in retardation of chemicals on a dry or wet surface sediment. High moisture in the air over the dry sediment increased the competition for sorption sites between water and contaminant and increased the contaminant flux.

  16. Update on Asteroid Density and Porosity

    NASA Astrophysics Data System (ADS)

    Britt, D. T.; Consolmagno, G. J.; Merline, W. J.

    2005-08-01

    Data on the bulk density of small bodies has exploded over the last 10 years (primarily from observations of asteroid satellites) and has led to significant insights into the structure of these objects [1,2]. This has contributed to the consensus that most small bodies have relatively low bulk densities and probably have significant porosity. Since then, new observations and planetary missions have provided a significantly expanded set of data, broadening the range of object types and sizes. These include the small icy moons measured by the Cassini mission, new AO observations of asteroid moons, new observations of small binaries using lightcurve techniques, new observations of NEO and TNO binaries, new data on comet and Centaur density, and new observations of Trojan binaries. These data provide a window into new size ranges and into new zones of the solar system. We review the available data and update our compilations of estimated porosity for small bodies. References: [1] Merline, W.J. et al. (2002) Asteroids III (Bottke W. et al., eds, 289-312. [2] Britt D.T. et al., (2002) Asteroids III (Bottke W. et al., eds), 485-500.

  17. Anisotropic and Hierarchical Porosity in Multifunctional Ceramics

    NASA Astrophysics Data System (ADS)

    Lichtner, Aaron Zev

    The performance of multifunctional porous ceramics is often hindered by the seemingly contradictory effects of porosity on both mechanical and non-structural properties and yet a sufficient body of knowledge linking microstructure to these properties does not exist. Using a combination of tailored anisotropic and hierarchical materials, these disparate effects may be reconciled. In this project, a systematic investigation of the processing, characterization and properties of anisotropic and isotropic hierarchically porous ceramics was conducted. The system chosen was a composite ceramic intended as the cathode for a solid oxide fuel cell (SOFC). Comprehensive processing investigations led to the development of approaches to make hierarchical, anisotropic porous microstructures using directional freeze-casting of well dispersed slurries. The effect of all the important processing parameters was investigated. This resulted in an ability to tailor and control the important microstructural features including the scale of the microstructure, the macropore size and total porosity. Comparable isotropic porous ceramics were also processed using fugitive pore formers. A suite of characterization techniques including x-ray tomography and 3-D sectional scanning electron micrographs (FIB-SEM) was used to characterize and quantify the green and partially sintered microstructures. The effect of sintering temperature on the microstructure was quantified and discrete element simulations (DEM) were used to explain the experimental observations. Finally, the comprehensive mechanical properties, at room temperature, were investigated, experimentally and using DEM, for the different microstructures.

  18. A three-dimensional hybrid finite element-volume tracking model for mould filling in casting processes

    NASA Astrophysics Data System (ADS)

    Gao, D. M.

    1999-04-01

    Metal casting is a complicated process in which flow momentum plays a crucial role in the mould filling process due to the high velocity of the liquid metal. Inertia and gravity effects may cause splashing, jetting or undesirable filling of the metal flow into the mould cavity. When considering complex parts, the accurate prediction of mould filling behaviour using empirical knowledge and intuition is nearly impossible. Therefore, numerical modelling and simulation are essential to predict such a complex physical problem and assist in part with mould design. A mould filling analysis can help the mould designer to determine the size and location of the gate as well as a proper runner system design for ensuring a complete and balanced filling of the part. Such an analysis can also be used to predict potential product defects, such as air entrapment, porosities, and help in correct positioning of overflows and venting systems. A three-dimensional finite element model combined with a volume tracking method has been developed in this work to simulate the cavity filling for casting processes. A mixed formulation based on a four node tetrahedral element with a bubble function at the centroid (P1+/P1) is employed to solve the flow equations. Such a finite element provides a small dimension of the element matrices and satisfies the Brezzi-Babuska condition to ensure a stable solution of the Navier-Stokes equations. A slip boundary condition combined with a friction model is implemented to better simulate the metal flow near the mould walls. An algebraic model is used to account for the turbulence effects during the mould filling. The flow fronts are tracked by a volume tracking method developed for the tetrahedral elements. This method can handle complicated flow front shapes and complex situations like merging and separation of flow fronts. The combination of a volume tracking technique with a FEM flow solver in three-dimensional unstructured meshes constitutes the major

  19. Influence of the porosity on the ²²²Rn exhalation rate of concrete.

    PubMed

    de Jong, Peter; van Dijk, Willem; de Rooij, Mario

    2011-02-01

    The composition of 23 concrete mixtures was varied in five separate series to evaluate the influence of porosity on the ²²²Rn exhalation rate. In each series, a range in porosities is obtained by varying (1) the amount of cement, (2) type of cement (Portland or blast furnace slag cement), (3) the amount of water at a fixed cement level, (4) addition of an air entraining agent, or (5) the amount of recycled aggregates. The porosities ranged from 1% to 16%. The ²²²Rn exhalation rate is normalized to the ²²⁶Ra activity concentration and expressed as the ²²²Rn release factor to eliminate the effect of differences in ²²⁶Ra activity concentrations among the various concrete mixtures. Since most ²²²Rn originates from the cement, a ²²²Rn release factor based on the amount of ²²⁶Ra introduced by the cements appeared to be more adequate. Although the methods to attain the porosities in the concrete mixtures differ widely, this cement-related factor corresponds well with the capillary porosity of the mixtures. Since the water-to-cement ratio of the fresh paste is a good indicator of the capillary porosity, this is the guiding factor in the fabrication of concretes low in ²²²Rn exhalation. The lower the water-to-cement ratio, the less capillary pore area will be available from which ²²²Rn can emanate from the mineral matrix into the pore system. The good correlation between the cement-based ²²²Rn release factor and literature data on the internal capillary pore area support the results of this study.

  20. How concentration of porosity, crack shape, and crack wall asperity control the seismic structure of the upper oceanic crust

    NASA Astrophysics Data System (ADS)

    Fontana, E.; Gilbert, L. A.; Marinoni, N.; Tartarotti, P.; Mancini, L.

    2015-12-01

    Surprisingly little is known about several important aspects of the architecture of oceanic crust, including controls on lithology, heterogeneity of hydrothermal alteration, and thickness of the lava section and sheeted dike complex and their influences on the seismic structure. Ophiolites provide useful analogs of ancient oceanic crust, with more exposure and access than deep-sea drill holes or submarine fracture zones. We examine the brittle structure of the lava, sheeted dikes, and lava-dike transition zone of the Troodos ophiolite (Cyprus) in the Lythrodontas area. The lava zone consists of pillow basalts; the transition zone consists of sheeted basaltic dikes cutting pillow lava through a large interval, and of hyaloclastitic breccia; the sheeted dikes are composed of 1-2 m thick basaltic or dacitic dikes. Detailed sample measurements of P- and S-wave velocity, permeability, porosity, and structures, show that porosity decreases drastically, as does permeability from lava to sheeted dikes. Variation of P-wave velocity mainly depends on the porosity, as well as the shapes of the cracks or pores. To better understand the relationships among P-wave velocity, porosity, and crack shape and aspect ratio, we made laboratory measurements using synchroton X-ray computed microtomography (micro-CT). Micro-CT images enhance the phase-contrast between primary (igneous) minerals and alteration minerals now filling the pores. Overall, quantitative data of the volume and shape of the pores (at the sample scale) allow us to evaluate the "empty" (effective) porosity as well as the paleo-porosity (pores now partially or completely filled with secondary minerals). We also quantify the asperity of crack walls. These measurements allow us to construct 3D structural patterns in the investigated ophiolite, which we use to examine the influence of cracks in the upper oceanic crust on seismic structure.

  1. Porosity evolution of upper Miocene reefs, Almeria Province, Southern Spain

    SciTech Connect

    Armstrong, A.K.; Snavely, P.D. Jr.; Addicott, W.O.

    1980-02-01

    In the reef cores and fore-reef breccia beds, porosity in both primary and postdepositional. Primary porosity is of three types: (a) boring clam holes in the scleractinian coral heads, cemented reef rocks, and breccias; (b) intraparticle porosity within the corals, Halimeda plates, and vermetid worm tubes; and (c) interparticle porosity between bioclastic fragments and in the reef breccia. Postdepositional moldic porosity was formed by the solution of aragonitic material such as molluscan and coral fragments. The Polomo reef carbonate rocks have high porosity and permeability, and retain a great amount of depositional porosity. Pores range in size from a few micrometers to 30 cm. The extensive intercrystalline porosity and high permeability resulted from dolomitization of micritic matrix. Some porosity reduction has occured by incomplete and partial sparry calcite infilling of interparticular, moldic, and intercrystalline voids. The high porosity and permeability of these reefs make them important targets for petroleum exploration in the western Mediterranean off southern Spain. In these offshore areas in the subsuface the volcanic ridge and the Plomo reef complex are locally onlapped or overlapped by 350 m or more of Miocene and Pliocene fine-grained sedimentary rocks. The possibility exists that the buried Plomo reef deposits may form traps for oil and gas in the offshore areas southwest of the type locality. Stratigraphic traps also may occur where the Neogene sequence above the Plomo reef complex onlaps the volcanic ridge. 17 figures.

  2. Gas filled panel insulation

    DOEpatents

    Griffith, B.T.; Arasteh, D.K.; Selkowitz, S.E.

    1993-12-14

    A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation. 18 figures.

  3. Gas filled panel insulation

    DOEpatents

    Griffith, Brent T.; Arasteh, Dariush K.; Selkowitz, Stephen E.

    1993-01-01

    A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation.

  4. Porosity change after gypsum crust formation on macro-porous limestones

    NASA Astrophysics Data System (ADS)

    Dewanckele, Jan; Cnudde, Veerle; de Kock, Tim; Boone, Marijn; Boone, Matthieu; van Hoorebeke, Luc; Jacobs, Patric

    2010-05-01

    filter, etc. were applied for the reconstruction. Total porosity, open and closed porosity and radial porosity were calculated for each sample by using the in-house developed software program Morpho+. The analysis of the various scans revealed that the Euville limestone developed a distinct gypsum crust, behind which a secondary porous layer of 100 μm thickness had developed. Inside the sample the porosity decreased by infilling of the large pore spaces with gypsum. However, after 6 days exposure the total porosity of the sample increased from 5.70% to 8.45%. In this case, the formation of secondary porosity behind the newly formed exterior gypsum layer prevailed upon the crystallizing of gypsum inside the pores located in the sample's interior. Also, the firstly formed gypsum crystals prevented the further interaction of the sulphuric acid with the stone material. After 21 days, the total porosity of the sample still reached 8.45%. The results of the radial porosity measurements were also the same after 6 and 21 days, indicating that the secondary porosity and the filling of pores inside the samples were stabilized. On the other hand, the gypsum crust on the Savonnières limestone was less visible. No secondary formed porous layer was measured and the total porosity decreased from 12.10% to 10.94% after 6 days and further to 10.31% at the end of the test. The decrease of porosity was still measurable at a depth of 500 μm inside the sample. The combination of micro-CT, image analysis and induced weathering tests are a promising combination of tools and techniques that allow for a better understanding of gypsum crust formation and pore structure change just behind the crust and deeper inside the rock sample.

  5. 3D Porosity Estimation of the Nankai Trough Sediments from Core-log-seismic Integration

    NASA Astrophysics Data System (ADS)

    Park, J. O.

    2015-12-01

    The Nankai Trough off southwest Japan is one of the best subduction-zone to study megathrust earthquake fault. Historic, great megathrust earthquakes with a recurrence interval of 100-200 yr have generated strong motion and large tsunamis along the Nankai Trough subduction zone. At the Nankai Trough margin, the Philippine Sea Plate (PSP) is being subducted beneath the Eurasian Plate to the northwest at a convergence rate ~4 cm/yr. The Shikoku Basin, the northern part of the PSP, is estimated to have opened between 25 and 15 Ma by backarc spreading of the Izu-Bonin arc. The >100-km-wide Nankai accretionary wedge, which has developed landward of the trench since the Miocene, mainly consists of offscraped and underplated materials from the trough-fill turbidites and the Shikoku Basin hemipelagic sediments. Particularly, physical properties of the incoming hemipelagic sediments may be critical for seismogenic behavior of the megathrust fault. We have carried out core-log-seismic integration (CLSI) to estimate 3D acoustic impedance and porosity for the incoming sediments in the Nankai Trough. For the CLSI, we used 3D seismic reflection data, P-wave velocity and density data obtained during IODP (Integrated Ocean Drilling Program) Expeditions 322 and 333. We computed acoustic impedance depth profiles for the IODP drilling sites from P-wave velocity and density data. We constructed seismic convolution models with the acoustic impedance profiles and a source wavelet which is extracted from the seismic data, adjusting the seismic models to observed seismic traces with inversion method. As a result, we obtained 3D acoustic impedance volume and then converted it to 3D porosity volume. In general, the 3D porosities show decrease with depth. We found a porosity anomaly zone with alteration of high and low porosities seaward of the trough axis. In this talk, we will show detailed 3D porosity of the incoming sediments, and present implications of the porosity anomaly zone for the

  6. Development of model hydroxyapatite bone scaffolds with multiscale porosity for potential load bearing applications

    NASA Astrophysics Data System (ADS)

    Dellinger, Jennifer Gwynne

    2005-11-01

    Model hydroxyapatite (HA) bone scaffolds consisting of a latticed pattern of rods were fabricated by a solid freeform fabrication (SFF) technique based on the robotic deposition of colloidal pastes. An optimal HA paste formulation for this method was developed. Local porosity, i.e. microporosity (1--30 mum) and sintering porosity (less than 1 mum), were produced by including polymer microsphere porogens in the HA pastes and by controlling the sintering of the scaffolds. Scaffolds with and without local porosity were evaluated with and without in vitro accelerated degradation. Percent weight loss of the scaffolds and calcium and phosphorus concentrations in solution increased with degradation time. After degradation, compressive strength and modulus decreased significantly for scaffolds with local porosity, but did not change significantly for scaffolds without local porosity. The compressive strength and modulus of scaffolds without local porosity were comparable to human cortical bone and were significantly greater than the scaffolds with local porosity. Micropores in HA disks caused surface pits that increased the surface roughness as compared to non-microporous HA disks. Mouse mesenchymal stem cells extended their cell processes into these microporous pits on HA disks in vitro. ALP expression was prolonged, cell attachment strength increased, and ECM production appeared greater on microporous HA disks compared to non-microporous HA disks and tissue culture treated polystyrene controls. Scaffolds with and without microporosity were implanted in goats bones. Microporous scaffolds with rhBMP-2 increased the percent of the scaffold filled with bone tissue compared to microporous scaffolds without rhBMP-2. Lamellar bone inside scaffolds was aligned near the rods junctions whereas lamellar bone was aligned in a more random configuration away from the rod junctions. Microporous scaffolds stained darkly with toluidine blue beneath areas of contact with new bone. This

  7. Designed porosity materials in nuclear reactor components

    DOEpatents

    Yacout, A. M.; Pellin, Michael J.; Stan, Marius

    2016-09-06

    A nuclear fuel pellet with a porous substrate, such as a carbon or tungsten aerogel, on which at least one layer of a fuel containing material is deposited via atomic layer deposition, and wherein the layer deposition is controlled to prevent agglomeration of defects. Further, a method of fabricating a nuclear fuel pellet, wherein the method features the steps of selecting a porous substrate, depositing at least one layer of a fuel containing material, and terminating the deposition when the desired porosity is achieved. Also provided is a nuclear reactor fuel cladding made of a porous substrate, such as silicon carbide aerogel or silicon carbide cloth, upon which layers of silicon carbide are deposited.

  8. Method for maintaining precise suction strip porosities

    NASA Technical Reports Server (NTRS)

    Gallimore, Frank H. (Inventor)

    1989-01-01

    This invention relates to a masking method generally and, more particularly to a method of masking perforated titanium sheets having laminar control suction strips. As illustrated in the drawings, a nonaerodynamic surface of a perforated sheet has alternating suction strip areas and bonding land areas. Suction strip tapes overlie the bonding land areas during application of a masking material to an upper surface of the suction strip tapes. Prior to bonding the perforated sheet to a composite structure, the bonding land tapes are removed. The entire opposite aerodynamic surface is masked with tape before bonding. This invention provides a precise control of suction strip porosities by ensuring that no chemicals penetrate the suction strip areas during bonding.

  9. Diagenesis and late-stage porosity development in the pennsylvanian strawn formation, val verde basin, Texas, U.S.A

    USGS Publications Warehouse

    David, Newell K.; Goldstein, R.H.; Burdick, C.J.

    2005-01-01

    The Middle Pennsylvanian (Desmoinesian) Strawn Formation in the Trans-Pecos area of Texas was deposited during relative tectonic quiescence that prevailed before rapid infilling of the Val Verde Basin. It represents one of a series of backstepping carbonate ramps formed on the craton side of this foreland basin. Strawn Formation carbonate rocks in three cores - Conoco Anna McClung #3-1, Alex Mitchell S2-1R, and Creek Ranch #10-1 - show several shallowing-up ward sequences, each a few meters thick. The Creek Ranch core displays the deepest-water characteristics of the three cores; the lower part of this core is dominated by graded bedding. The Mitchell and McClung cores contain skeletal-rich carbonates. Both of these cores display characteristics of shallow-water bank or lagoonal environments. All three cores have approximately the same diagenetic history. Primary fluid inclusions indicate early porosity-occluding interparticle and mold-filling calcite precipitated from water with a narrow range of salinities. Modal salinities are that of seawater, but slightly lesser salinities (indicating mixing of seawater and meteoric water) and slightly greater salinities (indicating evaporative concentration of seawater) are also indicated. The influence of meteoric groundwater can be detected by stable-isotope analyses of the early cements at stratigraphic levels that correlate to the tops of the major shallowing-upward depositional sequences. However, subaerial exposure surfaces are not demonstrated in these cores but were likely to be present updip. Most porosity is cement-reduced vugs, dissolution-enlarged (and cement-reduced) molds (> 1/16 mm, < 4 mm), and fractures. Minor intraparticle, intercrystalline, and shelter porosity is also present. Reservoir porosity is caused by fracturing and a late-stage dissolution event. Dissolution in the Creek Ranch core is not as pronounced as in the other cores because of a dearth of skeletal material. Porous zones in the McClung and

  10. Preimpact porosity controls the gravity signature of lunar craters

    NASA Astrophysics Data System (ADS)

    Milbury, C.; Johnson, B. C.; Melosh, H. J.; Collins, G. S.; Blair, D. M.; Soderblom, J. M.; Nimmo, F.; Bierson, C. J.; Phillips, R. J.; Zuber, M. T.

    2015-11-01

    We model the formation of lunar complex craters and investigate the effect of preimpact porosity on their gravity signatures. We find that while preimpact target porosities less than ~7% produce negative residual Bouguer anomalies (BAs), porosities greater than ~7% produce positive anomalies whose magnitude is greater for impacted surfaces with higher initial porosity. Negative anomalies result from pore space creation due to fracturing and dilatant bulking, and positive anomalies result from destruction of pore space due to shock wave compression. The central BA of craters larger than ~215 km in diameter, however, are invariably positive because of an underlying central mantle uplift. We conclude that the striking differences between the gravity signatures of craters on the Earth and Moon are the result of the higher average porosity and variable porosity of the lunar crust.

  11. Effect of Porosity Correlations on Sensitivity of Contaminant Travel Time

    NASA Astrophysics Data System (ADS)

    Pohlmann, K. F.; Zhu, J.; Chapman, J. B.; Russell, C. E.; Shafer, D. S.; Carroll, R. W.

    2010-12-01

    Effective porosity of hydrogeologic units (HGUs) is an important parameter influencing contaminant travel time and is particularly significant for applications where steady state Darcy flux is calculated from calibrated groundwater flow models. Under such circumstances, the effective porosities of HGUs along flowpaths are the primary control on advective velocities of particles and therefore contaminant travel times. As a result, the uncertainty in effective porosity is a critical source of uncertainty in the prediction of contaminant travel time, which is often required for designing networks for monitoring long-term migration of contaminants. In this study, uncorrelated and correlated sensitivities of advective contaminant travel times to porosities of HGUs were quantified using the advective travel time of contaminants from underground nuclear detonations at the Nevada Test Site to the Yucca Mountain area in Nevada U.S. as an example. First we investigated the importance of HGU porosities to the uncertainty of advective contaminant travel time based on Monte Carlo sampling techniques. We then partitioned the uncertainty of the advective travel time of contaminants into two portions: the correlated portion by the correlated variances (i.e. variances of an HGU porosity which are correlated with other HGU porosities) and the uncorrelated portion by the uncorrelated variations (i.e. the unique variations of an HGU porosity which cannot be expressed from other HGU porosities). Various correlation scenarios of HGU porosities were considered to examine the impacts of porosity correlations on the uncertainty and sensitivity of advective contaminant travel times. The emphasis is on how HGU porosity correlation scenarios influence uncorrelated and correlated uncertainty contributions.

  12. How gradients in porosity can make a better filter

    NASA Astrophysics Data System (ADS)

    Griffiths, Ian; Bruna, Maria; Dalwadi, Mohit

    2015-11-01

    Depth filters are a common device for removing contaminants from fluid. Porosity-graded filters, whose porosities decrease with depth, have been shown experimentally to offer improved filtration efficiency over filters with uniform porosity, by allowing contaminants to be trapped more evenly within the filter media. However, experiments are unable to probe the microscopic behavior, and so the underlying mechanisms that are responsible for this improved filtration are unclear. We use homogenization theory to derive a macroscopic model for the fluid flow and particle trapping within a porosity-graded depth filter. We find that gradients in porosity induce a macroscale particle advection in the direction of reducing porosity and show how particle trapping is more evenly spread through the filter for a decreasing porosity compared with a uniform porosity. By quantifying the removal rate, we show how a given operating regime can be fine-tuned to improve filter efficiency. The talk is accompanied by an online demonstration of MEMFI, a software package in which audience members may explore for themselves the effect of porosity gradients in user-specified operating regimes.

  13. Dye filled security seal

    DOEpatents

    Wilson, Dennis C. W.

    1982-04-27

    A security seal for providing an indication of unauthorized access to a sealed object includes an elongate member to be entwined in the object such that access is denied unless the member is removed. The elongate member has a hollow, pressurizable chamber extending throughout its length that is filled with a permanent dye under greater than atmospheric pressure. Attempts to cut the member and weld it together are revealed when dye flows through a rupture in the chamber wall and stains the outside surface of the member.

  14. Analogue modelisation of flow through a double porosity media with discrete conduits

    NASA Astrophysics Data System (ADS)

    Hakoun, V.; Pistre, S.; Karst; heterogeneous media-Hydrogeology, hydraulics; transfers

    2011-12-01

    In this study we describe a three dimensional meter scale experimental system used to investigate flow through a double porosity media that includes discrete flow conduits. This hybrid discrete-continuum approach is used to simulate water flow in karstic carbonate aquifers. A rectangular tank is filled with stacked ceramic foam blocks laterally separated with a constant aperture. The tank outlet is connected to a drilled conduit network that follows the overlying aperture scheme at the lower base of the system. Above the system, an artificial rain is set with a sprinkler. Working with an analogue model seems interesting as materials, initial and boundary conditions are fully known. Ceramic foam provides a uniform matrix material allowing different porosities and hydraulic conductivities. The modulability of the aperture pattern and size let different experiment setting possibilities. A variation in the drilled number of holes in the conduit network will change its draining capacity. And, finally the artificial rain rate and location are well characterized. The system is adequately instrumented in order to 1) observe hydraulic head distributions in both matrix and fracture medium and 2) record spring flow fluctuations. Moreover, any experience is very reproducible. This analogue modeling approach allows an observation of both fracture and matrix flow contribution to a spring with a drained double porosity media with discrete conduits. Comparison of in situ measured data with a finite element numerical model and an analytical solution are shown.

  15. Fluid Dynamics of Bottle Filling

    NASA Astrophysics Data System (ADS)

    McGough, Patrick; Gao, Haijing; Appathurai, Santosh; Basaran, Osman

    2011-11-01

    Filling of bottles is a widely practiced operation in a large number of industries. Well known examples include filling of ``large'' bottles with shampoos and cleaners in the household products and beauty care industries and filling of ``small'' bottles in the pharmaceutical industry. Some bottle filling operations have recently drawn much attention from the fluid mechanics community because of the occurrence of a multitude of complex flow regimes, transitions, and instabilities such as mounding and coiling that occur as a bottle is filled with a fluid. In this talk, we present a primarily computational study of the fluid dynamical challenges that can arise during the rapid filling of bottles. Given the diversity of fluids used in filling applications, we consider four representative classes of fluids that exhibit Newtonian, shear-thinning, viscoelastic, and yield-stress rheologies. The equations governing the dynamics of bottle filling are solved either in their full 3D but axisymmetric form or using the slender-jet approximation.

  16. Origin of dolomites in the Lower Cambrian Xiaoerbulak Formation in the Tarim Basin, NW China: Implications for porosity development

    NASA Astrophysics Data System (ADS)

    Li, Qing; Jiang, Zaixing; Hu, Wenxuan; You, Xuelian; Hao, Guoli; Zhang, Juntao; Wang, Xiaolin

    2016-01-01

    Dolomites occur pervasively in the Cambrian strata in the Tarim Basin, NW China. Although the Cambrian strata have been deeply buried and affected by multiple phases of dolomitization, some intervals in the upper part of the Lower Cambrian Xiaoerbulak Formation developed high porosity. The goal of this study is to understand the origin of different types of dolomites and the formation mechanism of the porosity in the Xiaoerbulak Formation. The geochemistry of matrix dolomites suggests that they formed from middle rare earth element (MREE)-enriched anoxic pore fluids, close to or within the zone of iron reduction. The similar REE + Y patterns and overlapping δ13C values between pore-filling and matrix dolomites indicate that the fluids that were responsible for the precipitation of pore-filling dolomite apparently inherited the signatures of the formation waters that were stored in the host strata. Low δ18O values coupled with high Ba, Zn, and rare earth element (REE) content of pore-filling dolomites indicate that pore-filling dolomites were formed at elevated temperatures. The precipitation of authigenic quartz and saddle dolomites and high Mn content in pore-filling dolomites indicate that hydrothermal fluids that mostly originated from Cambrian basinal clastic units or basement rocks were involved. The mixture of formation water and external hydrothermal fluids is the most likely explanation for the formation of significant porosity and precipitation of pore-filling dolomites at depth. Breccia dolomite, zebra dolomite, and saddle dolomite occur mostly in areas that are close to faults, which suggests that hydrothermal fluids passed through strike-slip faults in this area when these faults were activated. The development of permeable layers in the upper part of the Xiaoerbulak Formation overlain by impermeable layers of the Wusongger Formation suggests a possible potential diagenetic trap. When the faults were activated, high-pressure and high

  17. Hydrogen Filling Station

    SciTech Connect

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  18. Porosity and Health: Perspective of Traditional Persian Medicine

    PubMed Central

    Tafazoli, Vahid; Nimrouzi, Majid; Daneshfard, Babak

    2016-01-01

    Background: The authors of this manuscript aimed to show the importance of porosity and condensation in health according to traditional Persian medicine (TPM) with consideration of new evidence in conventional medicine. Methods: Cardinal traditional medical and pharmacological texts were searched for the traditional terms of takhalkhol (porosity) and takassof (condensity) focused on preventive methods. The findings were classified and compared with new medical findings. Results: According to traditional Persian medicine, porosity and condensity are the two crucial items that contribute to human health. Somatotype is a taxonomy based on embryonic development, which may be considered in parallel with porosity and condensation. However, these terms are not completely the same. There are many causes for acquired porosity comprising hot weather, too much intercourse, rage, starvation, and heavy exercises. In general, porosity increases the risk of diseases as it makes the body organs vulnerable to external hot and cold weather. On the other hand, the porose organs are more susceptible to accumulation of morbid matters because the cellular wastes cannot be evacuated in the normal way. There are some common points between traditional and conventional medicine in the context of porosity and condensity. The relation between diet and somatotype is an example. Conclusion: Condensity and porosity are the two basic items cited in the TPM resources and contribute to health maintenance and disease prevention of body organs. Creating a balance between these two states in different body organs, strongly contributes to disease prevention, treatment and diminishing chronic diseases period. Choosing proper modality including diet, drug therapy, and manual therapy depends on the amount porosity and stiffness of the considered organ and the preferred porosity of the affected organ keeping in a normal healthy state. PMID:27516679

  19. Porosity and Health: Perspective of Traditional Persian Medicine

    PubMed Central

    Tafazoli, Vahid; Nimrouzi, Majid; Daneshfard, Babak

    2016-01-01

    Background: The authors of this manuscript aimed to show the importance of porosity and condensation in health according to traditional Persian medicine (TPM) with consideration of new evidence in conventional medicine. Methods: Cardinal traditional medical and pharmacological texts were searched for the traditional terms of takhalkhol (porosity) and takassof (condensity) focused on preventive methods. The findings were classified and compared with new medical findings. Results: According to traditional Persian medicine, porosity and condensity are the two crucial items that contribute to human health. Somatotype is a taxonomy based on embryonic development, which may be considered in parallel with porosity and condensation. However, these terms are not completely the same. There are many causes for acquired porosity comprising hot weather, too much intercourse, rage, starvation, and heavy exercises. In general, porosity increases the risk of diseases as it makes the body organs vulnerable to external hot and cold weather. On the other hand, the porose organs are more susceptible to accumulation of morbid matters because the cellular wastes cannot be evacuated in the normal way. There are some common points between traditional and conventional medicine in the context of porosity and condensity. The relation between diet and somatotype is an example. Conclusion: Condensity and porosity are the two basic items cited in the TPM resources and contribute to health maintenance and disease prevention of body organs. Creating a balance between these two states in different body organs, strongly contributes to disease prevention, treatment and diminishing chronic diseases period. Choosing proper modality including diet, drug therapy, and manual therapy depends on the amount porosity and stiffness of the considered organ and the preferred porosity of the affected organ keeping in a normal healthy state. PMID:27840513

  20. Porosity and permeability of tuffs from the unsaturated zone at Yucca Mountain, Nevada

    SciTech Connect

    Soeder, D.J.; Dishart, J.E. )

    1992-01-01

    An investigation of the intrinsic flow properties of the rock matrix in the unsaturated zone at Yucca Mountain, Nevada, was carried out by performing single-phase water or air permeability measurements on about 150 selected samples representing all of the different rock units in the unsaturated zone. Pores were studied by examining thin sections of samples impregnated with fluorescent-dyed epoxy. Yucca Mountain is made up of volcanic tuff, which occurs in three distinct textures: welded, nonwelded, and bedded. Welded tuffs occur in two thick, rhyolitic, pyroclastic flow units. In thin sections, the typical welded-tuff pore structure appears to consist of isolated voids interconnected by microfractures. Porosities average about 10 percent, and matrix permeabilities are generally 1 microdarcy or less. The nonwelded tuffs occur in several thin pyroclastic flows between and below the two main welded units. Porosities average about 20 to 30%, and permeabilities are in the microdarcy to millidarcy range. The nonwelded tuffs appear in thin sections to have an open, well-interconnected pore system with significant intragranular porosity in pumice and lithic grains. These tuffs often contain various amounts of secondary clay and zeolite minerals in the pores, which may account for the wide range in permeabilities. The bedded tuffs consist of friable, low-density volcanic ash with porosities of 50% or more and permeabilities often above 1 darcy. These tuffs are the most porous and permeable rock units in the unsaturated zone, and contain large intergranular pores and significant intragranular porosity in frothy pumice clasts. Results of this investigation will help improve the understanding of groundwater movement through the unsaturated zone.

  1. Tunable-Porosity Membranes From Discrete Nanoparticles

    PubMed Central

    Marchetti, Patrizia; Mechelhoff, Martin; Livingston, Andrew G.

    2015-01-01

    Thin film composite membranes were prepared through a facile single-step wire-wound rod coating procedure in which internally crosslinked poly(styrene-co-butadiene) polymer nanoparticles self-assembled to form a thin film on a hydrophilic ultrafiltration support. This nanoparticle film provided a defect-free separation layer 130–150 nm thick, which was highly permeable and able to withstand aggressive pH conditions beyond the range of available commercial membranes. The nanoparticles were found to coalesce to form a rubbery film when heated above their glass transition temperature (Tg). The retention properties of the novel membrane were strongly affected by charge repulsion, due to the negative charge of the hydroxyl functionalized nanoparticles. Porosity was tuned by annealing the membranes at different temperatures, below and above the nanoparticle Tg. This enabled fabrication of membranes with varying performance. Nanofiltration properties were achieved with a molecular weight cut-off below 500 g mol−1 and a low fouling tendency. Interestingly, after annealing above Tg, memory of the interstitial spaces between the nanoparticles persisted. This memory led to significant water permeance, in marked contrast to the almost impermeable films cast from a solution of the same polymer. PMID:26626565

  2. Tunable-Porosity Membranes From Discrete Nanoparticles

    NASA Astrophysics Data System (ADS)

    Marchetti, Patrizia; Mechelhoff, Martin; Livingston, Andrew G.

    2015-12-01

    Thin film composite membranes were prepared through a facile single-step wire-wound rod coating procedure in which internally crosslinked poly(styrene-co-butadiene) polymer nanoparticles self-assembled to form a thin film on a hydrophilic ultrafiltration support. This nanoparticle film provided a defect-free separation layer 130-150 nm thick, which was highly permeable and able to withstand aggressive pH conditions beyond the range of available commercial membranes. The nanoparticles were found to coalesce to form a rubbery film when heated above their glass transition temperature (Tg). The retention properties of the novel membrane were strongly affected by charge repulsion, due to the negative charge of the hydroxyl functionalized nanoparticles. Porosity was tuned by annealing the membranes at different temperatures, below and above the nanoparticle Tg. This enabled fabrication of membranes with varying performance. Nanofiltration properties were achieved with a molecular weight cut-off below 500 g mol-1 and a low fouling tendency. Interestingly, after annealing above Tg, memory of the interstitial spaces between the nanoparticles persisted. This memory led to significant water permeance, in marked contrast to the almost impermeable films cast from a solution of the same polymer.

  3. Water uptake in biochars: The roles of porosity and hydrophobicity

    EPA Science Inventory

    We assessed the effects of porosity and hydrophobicity on water uptake by biochars. Biochars were produced from two feedstocks (hazelnut shells and Douglas fir chips) at three production temperatures (370 °C, 500 °C, and 620 °C). To distinguish the effects of porosity from the ...

  4. Low porosity metallic periodic structures with negative Poisson's ratio.

    PubMed

    Taylor, Michael; Francesconi, Luca; Gerendás, Miklós; Shanian, Ali; Carson, Carl; Bertoldi, Katia

    2014-04-16

    Auxetic behavior in low porosity metallic structures is demonstrated via a simple system of orthogonal elliptical voids. In this minimal 2D system, the Poisson's ratio can be effectively controlled by changing the aspect ratio of the voids. In this way, large negative values of Poisson's ratio can be achieved, indicating an effective strategy for designing auxetic structures with desired porosity.

  5. Casting Porosity-Free Grain Refined Magnesium Alloys

    SciTech Connect

    Schwam, David

    2013-08-12

    The objective of this project was to identify the root causes for micro-porosity in magnesium alloy castings and recommend remedies that can be implemented in production. The findings confirm the key role played by utilizing optimal gating and risering practices in minimizing porosity in magnesium castings. 

  6. Changes in porosity and organic matter phase distribution monitored by NMR relaxometry following hydrous pyrolysis under uniaxial confinement

    USGS Publications Warehouse

    Washburn, Kathryn E.; Birdwell, Justin E.; Lewan, Michael D.; Miller, Michael; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    Artificial maturation methods are used to induce changes in source rock thermal maturity without the uncertainties that arise when comparing natural samples from a particular basin that often represent different levels of maturation and different lithofacies. A novel uniaxial confinement clamp was used on Woodford Shale cores in hydrous pyrolysis experiments to limit sample expansion by simulating the effect of overburden present during thermal maturation in natural systems. These samples were then subjected to X-ray computed tomography (X-CT) imaging and low-field nuclear magnetic resonance (LF-NMR) relaxometry measurements. LF-NMR relaxometry is a noninvasive technique commonly used to measure porosity and pore-size distributions in fluid-filled porous media, but may also measure hydrogen present in hydrogen-bearing organic solids. Standard T1 and T2 relaxation distributions were determined and two dimensional T1-T2 correlation measurements were performed on the Woodford Shale cores. The T1-T2 correlations facilitate resolution of organic phases in the system. The changes observed in NMR-relaxation times correspond to bitumen and lighter hydrocarbon production that occur as source rock organic matter matures. The LF-NMR porosities of the core samples at maximum oil generation are significantly higher than porosities measured by other methods. This discrepancy likely arises from the measurement of highly viscous organic constituents in addition to fluid-filled porosity. An unconfined sample showed shorter relaxation times and lower porosity. This difference is attributed to the lack of fractures observed in the unconfined sample by X-CT.

  7. Space-filling percolation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhijit; Manna, S. S.

    2014-03-01

    A region of two-dimensional space has been filled randomly with a large number of growing circular disks allowing only a "slight" overlapping among them just before their growth stops. More specifically, each disk grows from a nucleation center that is selected at a random location within the uncovered region. The growth rate δ is a continuously tunable parameter of the problem which assumes a specific value while a particular pattern of disks is generated. When a growing disk overlaps for the first time with at least one other disk, its growth is stopped and is said to be frozen. In this paper we study the percolation properties of the set of frozen disks. Using numerical simulations we present evidence for the following: (i) The order parameter appears to jump discontinuously at a certain critical value of the area coverage; (ii) the width of the window of the area coverage needed to observe a macroscopic jump in the order parameter tends to vanish as δ →0; and on the contrary (iii) the cluster size distribution has a power-law-decaying functional form. While the first two results are the signatures of a discontinuous transition, the third result is indicative of a continuous transition. Therefore we refer to this transition as a sharp but continuous transition similar to what has been observed in the recently introduced Achlioptas process of explosive percolation. It is also observed that in the limit of δ →0, the critical area coverage at the transition point tends to unity, implying that the limiting pattern is space filling. In this limit, the fractal dimension of the pore space at the percolation point has been estimated to be 1.42(10) and the contact network of the disk assembly is found to be a scale-free network.

  8. Processing of thermal insulation materials with controlled porosity

    SciTech Connect

    Lyckfeldt, O.; Liden, E.; Carlsson, R.

    1995-08-01

    Slip-cast cordierite-based materials with reduced thermal conductivity have been manufactured with controlled introduction of porosity. The porosity was obtained by addition of different kinds of fillers (hollow Al-silicate spheres, paraffin, polystyrene, carbon black or starch particles). The processing and the ultimate thermal and mechanical properties were evaluated. The results showed that additions of corn or potato starch gave the most favourable concept, considering the processing and porosity control. A homogeneous distribution of spherical pores with the sizes 5-25 or 15-40 {mu}m was obtained after sintering. Slip-cast cordierite with 37% porosity had a thermal conductivity of 1.7 W/mK (compared with 3.7 W/mK for fully dense cordierite), and a bending strength above 50 MPa. The porosity effect correlated very well to theoretical models by Maxwell and, hence, the thermal conductivity of the porous ceramic material could be predicted.

  9. Results from a new Cocks-Ashby style porosity model

    NASA Astrophysics Data System (ADS)

    Barton, Nathan

    2015-06-01

    A new porosity evolution model will be described, along with preliminary results. The formulation makes use of a Cocks-Ashby style treatment of porosity kinetics that includes rate dependent flow in the mechanics of porosity growth. The porosity model is implemented in a framework that allows for a variety of strength models to be used for the matrix material, including ones with significant changes in rate sensitivity as a function of strain rate. Results of the effect of changing strain rate sensitivity on porosity evolution will be shown. The overall constitutive model update involves the coupled solution of a system of nonlinear equations - efficiency and robustness of the numerical implementation are significant issues. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 (LLNL-ABS-666658).

  10. Advanced Aerodynamic Design of Passive Porosity Control Effectors

    NASA Technical Reports Server (NTRS)

    Hunter, Craig A.; Viken, Sally A.; Wood, Richard M.; Bauer, Steven X. S.

    2001-01-01

    This paper describes aerodynamic design work aimed at developing a passive porosity control effector system for a generic tailless fighter aircraft. As part of this work, a computational design tool was developed and used to layout passive porosity effector systems for longitudinal and lateral-directional control at a low-speed, high angle of attack condition. Aerodynamic analysis was conducted using the NASA Langley computational fluid dynamics code USM3D, in conjunction with a newly formulated surface boundary condition for passive porosity. Results indicate that passive porosity effectors can provide maneuver control increments that equal and exceed those of conventional aerodynamic effectors for low-speed, high-alpha flight, with control levels that are a linear function of porous area. This work demonstrates the tremendous potential of passive porosity to yield simple control effector systems that have no external moving parts and will preserve an aircraft's fixed outer mold line.

  11. Treatment of domestic wastewater by subsurface flow constructed wetlands filled with gravel and tire chip media.

    PubMed

    Richter, A Y; Weaver, R W

    2003-12-01

    Subsurface flow constructed wetlands (SFCWs) are becoming increasingly common in on-site treatment of wastewater. Gravel is the most popular form of wetland fill medium, but tire chips provide more porosity, are less dense, and less expensive. This study determines the treatment efficiency of SFCWs filled with gravel or tire chip media to treat domestic wastewater. The influent and effluent of six SFCWs filled with tire chip medium and six SFCWs filled with gravel were monitored for 5 to 16 consecutive months. Parameters measured included pH, biochemical oxygen demand (BOD5), total and volatile suspended solids, NH4, P, and fecal and total coliforms. The only clear difference between medium types in wetland performance was for P. Soluble P in the effluent averaged 1.6 +/- 1.0 mg l(-1) in the tire chip-filled wetlands and 4.8 +/- 3.2 mg l(-1) in the gravel-filled wetlands. Most likely, Fe from exposed wires in shredded steel-belted tires complexed with P to create an insoluble compound. Tire chips may be a better fill medium for SFCWs than gravel because of higher porosity, lower cost, and greater reduction of P in effluent.

  12. Porosity as a significant factor for asteroid survival

    NASA Astrophysics Data System (ADS)

    Flynn, G. J.

    2014-07-01

    Most asteroids, for which porosities have been inferred, have porosities ranging from 20 % to > 50 %, with a mean around 30 % porosity (Britt et al. 2002). Since porous targets react differently to hypervelocity impact cratering and disruption than non-porous targets of the same mass, porosity is likely to play a role in asteroid survival. Measurements show the threshold collisional specific energy, Q^*_D, required to produce a disruption with the largest fragment equal to one-half the original target mass is much higher for porous targets (Table). Ordinary chondrite meteorites, with a mean porosity of ˜9 % (Britt et al. 2002), disrupted at the NASA Ames Vertical Gun Range (AVGR), required almost twice as much impactor kinetic energy per unit target mass to produce an equivalent disruption as did targets of low-porosity terrestrial basalt or granodiorite (Flynn and Durda 2004). Limited data from hypervelocity disruption of three CM2 carbonaceous chondrites (Flynn et al. 2009), all to the right of the ordinary chondrite points on a Q^* vs. M_L/M_T plot, indicate CM2 meteorites, with a mean porosity of 23 % (Consolmagno et al. 2008), have even higher Q^*_D, ˜1900 to 2100 J/kg. The CI carbonaceous chondrites, e.g., Orgueil, with a density of 1.5 g/cm^3 (Britt and Consolmagno 2003) and porosity of 35 % (Consolmagno et al. 2008), are the most porous known meteorites, approaching the C-type asteroid Mathilde, which has a bulk density of 1.3 and > 50 % porosity (Britt et al., 2002). However, the CI meteorites are so scarce than none have yet been studied in impact experiments. As an extreme end member for high-porosity, rigid targets, Flynn et al. (2014) disrupted eleven terrestrial pumice targets, obtaining a Q^*_D of ˜2300 J/kg. However, porosity increases the target's cross section. The ''Required Disruption Energy'' to produce a largest fragment mass equal to one- half the target mass for spherical asteroids of 10-m, 1-km, and 100-km radius having the same physical

  13. Porosity evolution, contact metamorphism, and fluid flow in the host basalts of the Skaergaard magma-hydrothermal system

    SciTech Connect

    Manning, C.E.

    1989-01-01

    Temporal and spatial variations in porosity during contact metamorphism of the basaltic country rocks to the Skaergaard intrusion in East Greenland resulted in a complex hydrological evolution of the metamorphic aureole. Contrasts in macroscopic porosities in different lithologies led to differences in mineralogical, bulk chemical, and oxygen isotopic alteration, and units with greater macroscopic porosities record larger fluid flux during metamorphism. Calculated Darcy velocities indicate that the horizontal component of fluid flow in the aureole was toward the intrusive contact. In the actinolite + chlorite zone time-integrated fluid flux was higher in aa units ({approximately} 300 kg cm{sup {minus}2}) than in massive units ({approximately} 130 kg cm{sup {minus}2}). Approximately equal time-integrated fluxes of respectively 4 and 5 kg cm{sup {minus}2} in aa and massive units in the pyroxene zone indicate that the volume of fluid flow in the higher grade rocks was independent of primary porosity. These results are consistent with inward fluid migration in the actinolite + chlorite zone through an open network of pores whose abundance varied as a function of primary lava morphology. At higher metamorphic grades fluid fluxes were lower and were independent of primary porosity, probably as a consequence of (1) channelization of fluids due to more extensive pore filling and (2) decreasing horizontal component of flow due to upward migration of fluids near the contact. The results of this study indicate that explicit provision for rock porosity aids interpretation of the nature of fluid flow during contact metamorphism in magma-hydrothermal systems.

  14. Effect of quartz overgrowth precipitation on the multiscale porosity of sandstone: A (U)SANS and imaging analysis

    DOE PAGES

    Anovitz, Lawrence M.; Cole, David R.; Jackson, Andrew J.; ...

    2015-06-01

    We have performed a series of experiments to understand the effects of quartz overgrowths on nanometer to centimeter scale pore structures of sandstones. Blocks from two samples of St. Peter Sandstone with different initial porosities (5.8 and 18.3%) were reacted from 3 days to 7.5 months at 100 and 200 °C in aqueous solutions supersaturated with respect to quartz by reaction with amorphous silica. Porosity in the resultant samples was analyzed using small and ultrasmall angle neutron scattering and scanning electron microscope/backscattered electron (SEM/BSE)-based image-scale processing techniques.Significant changes were observed in the multiscale pore structures. By three days much ofmore » the overgrowth in the low-porosity sample dissolved away. The reason for this is uncertain, but the overgrowths can be clearly distinguished from the original core grains in the BSE images. At longer times the larger pores are observed to fill with plate-like precipitates. As with the unreacted sandstones, porosity is a step function of size. Grain boundaries are typically fractal, but no evidence of mass fractal or fuzzy interface behavior was observed suggesting a structural difference between chemical and clastic sediments. After the initial loss of the overgrowths, image scale porosity (>~1 cm) decreases with time. Submicron porosity (typically ~25% of the total) is relatively constant or slightly decreasing in absolute terms, but the percent change is significant. Fractal dimensions decrease at larger scales, and increase at smaller scales with increased precipitation.« less

  15. Gradient porous electrode architectures for rechargeable metal-air batteries

    DOEpatents

    Dudney, Nancy J.; Klett, James W.; Nanda, Jagjit; Narula, Chaitanya Kumar; Pannala, Sreekanth

    2016-03-22

    A cathode for a metal air battery includes a cathode structure having pores. The cathode structure has a metal side and an air side. The porosity decreases from the air side to the metal side. A metal air battery and a method of making a cathode for a metal air battery are also disclosed.

  16. Lava-Filled Craters

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 12 June 2003

    Craters and hills form high standing streamlined plateaus or islands in a channeled area. The plateaus are rounded in the upstream direction and taper to a point in the downstream direction, indicating that the direction of flow in this area was roughly south to north, or bottom to top. The channels appear to be filled with lava flow deposits that are raised above the channel in some areas. A lava flow diverges around a small streamlined hill near the bottom of the image and then merges again around the northern end of it. Near the top of the image is a crater with a breach on the east (right) side that allowed the lava to flow in, leaving a lobate, high standing deposit. The channels may have been formed by the lava flows that currently fill them or there may have been flow of liquid water that created them before the lava was emplaced.

    Image information: VIS instrument. Latitude 16, Longitude 183 East (177 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built

  17. Deep porosity preservation in the Norphlet Formation, Mobil Bay, Alabama

    SciTech Connect

    Ajdukiewicz, J.M.; Paxton, S.T.; Szabvo, J.O. )

    1991-03-01

    Compaction and pressure solution have commonly been assumed to destroy primary intergranular porosity in deeply buried sandstones. However, primary porosities of up to 20% are preserved at depths greater than 20,000 feet in the Norphlet Formation of Mobile Bay. Previous workers have called upon a number of mechanisms to preserve these high porosities in the Norphlet, specifically chlorite rim cements, gas emplacement, overpressuring, and decementation. In contrast, our study of data from 23 Norphlet wells, including 450 thin sections, indicates that these suggested mechanisms are not the primary cause of porosity preservation in the Norphlet. The authors propose an alternative interpretation: that in the Norphlet, as in other well-sorted, ductile-grain-poor sandstones, porosity loss from compaction did not go to completion under reservoir (premetamorphic) conditions, but stabilized at depths of about 5,000-8,000 feet and porosity values of about 26%. Porosity loss below these values is due to cementation. For cementation to occur, both an adequate source of cement and geochemical conditions favoring cement precipitation must be present. Computer simulations of Norphlet burial history, including post-depositional fluid-flow patterns, suggest that conditions favorable to quartz cementation never occurred in the bulk of the Norphlet because of the formation's stratigraphic position and isolation from a basinward source of silica-saturated fluids.

  18. Friction Factor Characterization for High-Porosity Random Fiber Regenerators

    NASA Technical Reports Server (NTRS)

    Thieme, Lanny G.

    2001-01-01

    NASA Glenn Research Center, the Department of Energy (DOE), and Stirling Technology Company (STC) of Kennewick, Washington are developing a Stirling convertor for a high-efficiency Stirling Radioisotope Power System to provide electric power for NASA Space Science Missions. STC is developing the 55-We Technology Demonstration Convertor (TDC) under contract to DOE. Steady-flow tests were completed to determine the friction factor for the high-porosity regenerators that are used in the TDC. STC fabricated a flow test fixture and three random fiber regenerator test samples, one each at approximately 80, 88, and 96 percent porosities. The flow tests were then completed by the NASA Glenn Flow Calibration Laboratory, and the data reduced to Reynolds number and friction factor. The results showed that the 80 and 88 percent porosity samples had similar characteristics while the 96 percent porosity sample had significantly higher friction factors for given Reynolds numbers compared to the samples with lower porosities. Comparisons were also made between the test data and existing correlations. STC used this data to derive a modified regenerator friction factor correlation for use in the Stirling design code GLIMPS for porosities greater than 88 percent. Using this new correlation, the final optimized regenerator design porosity was reduced from 96 to 90 percent.

  19. Soil surface roughness and porosity under different tillage systems

    NASA Astrophysics Data System (ADS)

    Rodriguez-Gonzalez, J.; Saa-Requejo, A.; Gómez, J. A.; Valencia, J. L.; Zarco, P.; Tarquis, A. M.

    2012-04-01

    Both soil porosity and surface elevation can be altered by tillage operation. Even though the surface porosity is an important parameter of a tilled field, however, no practical technique for rapid and non-contact measurement of surface porosity has been developed yet. On the contrary, the surface elevation of tilled soil can be quickly determined with a laser profiler. Working under the assumption that the surface elevation of a tilled field is a complicated superposition of the soil terrain profile at a larger-scale and the roughness at a fine-scale, this study included three aspects: (i) to establish an index (Roughness Index, RI) at a fine-scale to associate the surface roughness with porosity; (ii) to examine the correlation between surface porosity and the proposed RI by three types of tillage treatment in the field; and (iii) to check the scaling/multiscaling behavior among different grid sizes of calculating RI on predicting surface porosity. Consequently, the statistical results from each tilled plot show a strong correlation between the surface porosity and the defined RI in an early stage (ca. 2 days) after tillage. Acknowledgements Funding provided by CEIGRAM (Research Centre for the Management of Agricultural and Environmental Risks)and Spanish Ministerio de Ciencia e Innovación (MICINN) through project AGL2010-21501/AGR is greatly appreciated.

  20. Effect of Porosity on Strength Distribution of Microcrystalline Cellulose.

    PubMed

    Keleṣ, Özgür; Barcenas, Nicholas P; Sprys, Daniel H; Bowman, Keith J

    2015-12-01

    Fracture strength of pharmaceutical compacts varies even for nominally identical samples, which directly affects compaction, comminution, and tablet dosage forms. However, the relationships between porosity and mechanical behavior of compacts are not clear. Here, the effects of porosity on fracture strength and fracture statistics of microcrystalline cellulose compacts were investigated through diametral compression tests. Weibull modulus, a key parameter in Weibull statistics, was observed to decrease with increasing porosity from 17 to 56 vol.%, based on eight sets of compacts at different porosity levels, each set containing ∼ 50 samples, a total of 407 tests. Normal distribution fits better to fracture data for porosity less than 20 vol.%, whereas Weibull distribution is a better fit in the limit of highest porosity. Weibull moduli from 840 unique finite element simulations of isotropic porous materials were compared to experimental Weibull moduli from this research and results on various pharmaceutical materials. Deviations from Weibull statistics are observed. The effect of porosity on fracture strength can be described by a recently proposed micromechanics-based formula.

  1. Defining filled and empty space: reassessing the filled space illusion for active touch and vision.

    PubMed

    Collier, Elizabeth S; Lawson, Rebecca

    2016-09-01

    In the filled space illusion, an extent filled with gratings is estimated as longer than an equivalent extent that is apparently empty. However, researchers do not seem to have carefully considered the terms filled and empty when describing this illusion. Specifically, for active touch, smooth, solid surfaces have typically been used to represent empty space. Thus, it is not known whether comparing gratings to truly empty space (air) during active exploration by touch elicits the same illusionary effect. In Experiments 1 and 2, gratings were estimated as longer if they were compared to smooth, solid surfaces rather than being compared to truly empty space. Consistent with this, Experiment 3 showed that empty space was perceived as longer than solid surfaces when the two were compared directly. Together these results are consistent with the hypothesis that, for touch, the standard filled space illusion only occurs if gratings are compared to smooth, solid surfaces and that it may reverse if gratings are compared to empty space. Finally, Experiment 4 showed that gratings were estimated as longer than both solid and empty extents in vision, so the direction of the filled space illusion in vision was not affected by the nature of the comparator. These results are discussed in relation to the dual nature of active touch.

  2. The dynamic response of carbon fiber-filled polymer composites

    NASA Astrophysics Data System (ADS)

    Dattelbaum, D. M.; Gustavsen, R. L.; Sheffield, S. A.; Stahl, D. B.; Scharff, R. J.; Rigg, P. A.; Furmanski, J.; Orler, E. B.; Patterson, B.; Coe, J. D.

    2012-08-01

    The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6 GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 ×up(ρ0 = 1.536g/cm3). The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP) composite to much higher shock input pressures, exceeding the reactants-to-products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall) for the CE composite in the TT and 0∘ (fiber) directions.

  3. Acute sensitivity of landslide rates to initial soil porosity

    USGS Publications Warehouse

    Iverson, R.M.; Reid, M.E.; Iverson, N.R.; LaHusen, R.G.; Logan, M.; Mann, J.E.; Brien, D.L.

    2000-01-01

    Some landslides move imperceptibly downslope, whereas others accelerate catastrophically. Experimental landslides triggered by rising pore water pressure moved at sharply contrasting rates due to small differences in initial porosity. Wet sandy soil with porosity of about 0.5 contracted during slope failure, partially liquefied, and accelerated within 1 second to speeds over I meter per second. The same soil with porosity of about 0.4 dilated during failure and supped episodically at rates averaging 0.002 meter per second. Repeated slip episodes were induced by gradually rising pore water pressure and were arrested by pore dilation and attendant pore pressure decline.

  4. Ultrasonic measurement of porosity in casts and welds

    NASA Astrophysics Data System (ADS)

    Adler, L.; Wang, S. W.

    1986-01-01

    The development of a quantitative nondestructive method which involves ultrasonic attenuation measurements in frequency domain to determine volume fraction of porosity in aluminum cast is discussed. The aluminum alloy A357 casting samples were produced at the Ohio State University Foundry with controlled porosity contents ranging from 0% to 6%. A computer controlled system was used to direct ultrasonic beam to a test sample to different places to conduct ultrasonic attenuation measurements. The plot of attenuation coefficients as a function of frequency was then evaluated based on existing theories to determine volume fraction of porosity and pore size.

  5. Role of porosity and pore architecture in the in vivo bone regeneration capacity of biodegradable glass scaffolds.

    PubMed

    Sanzana, Edgardo S; Navarro, Melba; Ginebra, Maria-Pau; Planell, Josep A; Ojeda, Alvaro C; Montecinos, Hernan A

    2014-06-01

    The aim of this work is to shed light on the role of porosity and pore architecture in the in vivo bone regeneration capacity of biodegradable glass scaffolds. A calcium phosphate glass in the system P2O5-CaO-Na2O-TiO2 was foamed using two different porogens, namely albumen and hydrogen peroxide (H2O2); the resulting three-dimensional porous structures were characterized and implanted in New Zealand rabbits to study their in vivo behavior. Scaffolds foamed with albumen displayed a monomodal pore size distribution centered around 150 μm and a porosity of 82%, whereas scaffolds foamed with H2O2 showed lower porosity (37%), with larger elongated pores, and multimodal size distribution. After 12 weeks of implantation, histology results revealed a good osteointegration for both types of scaffolds. The quantitative morphometric analysis showed the substitution of the biomaterial by new bone in the case of glasses foamed with albumen. In contrast, bone neoformation and material resorption were significantly lower in the defects filled with the scaffolds foamed with H2O2. The results obtained in this study showed that both calcium phosphate glass scaffolds were osteoconductive, biocompatible, and biodegradable materials. However, differences in porosity, pore architecture, and microstructure led to substantially different in vivo response.

  6. A feasible research of rock porosity and water saturation impact on audio-magnetotelluric propagation in porous media

    NASA Astrophysics Data System (ADS)

    Tian, Z.; Liu, J.

    2015-12-01

    Abstract: Although various factors have impact on the resistivity of subsurface rock formation, in depth range of general electrical prospecting, the conductive actions of rocks are basically realized relying on the aqueous solutions filled in the pores. Therefore, quantitatively studying the impact of the water level on rock resistivity is important to analyze and classify strata, investigate the underground structures. In this research, we proposed a feasible research on building electric property rock formation models with different porosity and water saturation based on theories of two-phase media. The propagation of audio-magnetotelluric (AMT) waves is simulated by using finite-difference (FD) scheme, and theoretic resistivity distribution is calculated on account of the response of AMT. According to a sequence of synthetic examples, through comparing and analyzing the simulated results with various porosity and water saturation respectively, we discuss the impact on layers resistivity while porosity and water saturation of rock stratum are changing. The results shows the extent that the mentioned factors can have impact on the propagation of AMT waves. Key words: audio-magnetotelluric modeling, two-phase media, porosity, water saturation, finite-difference

  7. Intermittent Surface Water Connectivity: Fill and Spill vs. Fill ...

    EPA Pesticide Factsheets

    Intermittent surface connectivity can influence aquatic systems, since chemical and biotic movements are often associated with water flow. Although often referred to as fill and spill, wetlands also fill and merge. We examined the effects of these connection types on water levels, ion concentrations, and biotic communities of eight prairie pothole wetlands between 1979 and 2015. Fill and spill caused pulsed surface water connections that were limited to periods following spring snow melt. In contrast, two wetlands connected through fill and merge experienced a nearly continuous, 20-year surface water connection and had completely coincident water levels. Fill and spill led to minimal convergence in dissolved ions and macroinvertebrate composition, while these constituents converged under fill and merge. The primary factor determining difference in responses was duration of the surface water connection between wetland pairs. Our findings suggest that investigations into the effects of intermittent surface water connections should not consider these connections generically, but need to address the specific types of connections. In particular, fill and spill promotes external water exports while fill and merge favors internal storage. The behaviors of such intermittent connections will likely be accentuated under a future with more frequent and severe climate extremes. Under the Safe and Sustainable Water Resources National Program, work is being done to qu

  8. Study of acoustic radiation during air stream filtration through a porous medium

    NASA Astrophysics Data System (ADS)

    Zaslavskii, Yu. M.; Zaslavskii, V. Yu.

    2012-11-01

    The paper presents results of laboratory experiments on studying the characteristics of acoustic emission generated by a flow of compressed air, which is filtered by porous pumice samples with and without partial fluid saturation. The construction features of the laboratory setup and details of the experiments are described. Porous samples with dry and partially fluid-filled pores are used. The visual patterns of the acoustic emission spectrum, which occurs under stationary filtration of the compressed air, are presented, and its amplitude-frequency distribution characteristic for different sample porosities and different degrees of their fluid saturation is shown. It is demonstrated that the relaxation times of the emission noise level differ. This is revealed during the sharp elimination of the drop in pressure from such samples, i.e., in the nonstationary filtration mode.

  9. Control of porosity and pore size of metal reinforced carbon nanotube membranes.

    PubMed

    Dumee, Ludovic; Velleman, Leonora; Sears, Kallista; Hill, Matthew; Schutz, Jurg; Finn, Niall; Duke, Mikel; Gray, Stephen

    2010-12-21

    Membranes are crucial in modern industry and both new technologies and materials need to be designed to achieve higher selectivity and performance. Exotic materials such as nanoparticles offer promising perspectives, and combining both their very high specific surface area and the possibility to incorporate them into macrostructures have already shown to substantially increase the membrane performance. In this paper we report on the fabrication and engineering of metal-reinforced carbon nanotube (CNT) Bucky-Paper (BP) composites with tuneable porosity and surface pore size. A BP is an entangled mesh non-woven like structure of nanotubes. Pure CNT BPs present both very high porosity (>90%) and specific surface area (>400 m2/g). Furthermore, their pore size is generally between 20-50 nm making them promising candidates for various membrane and separation applications. Both electro-plating and electroless plating techniques were used to plate different series of BPs and offered various degrees of success. Here we will report mainly on electroless plated gold/CNT composites. The benefit of this method resides in the versatility of the plating and the opportunity to tune both average pore size and porosity of the structure with a high degree of reproducibility. The CNT BPs were first oxidized by short UV/O3 treatment, followed by successive immersion in different plating solutions. The morphology and properties of these samples has been investigated and their performance in air permeation and gas adsorption will be reported.

  10. Control of Porosity and Pore Size of Metal Reinforced Carbon Nanotube Membranes

    PubMed Central

    Dumee, Ludovic; Velleman, Leonora; Sears, Kallista; Hill, Matthew; Schutz, Jurg; Finn, Niall; Duke, Mikel; Gray, Stephen

    2011-01-01

    Membranes are crucial in modern industry and both new technologies and materials need to be designed to achieve higher selectivity and performance. Exotic materials such as nanoparticles offer promising perspectives, and combining both their very high specific surface area and the possibility to incorporate them into macrostructures have already shown to substantially increase the membrane performance. In this paper we report on the fabrication and engineering of metal-reinforced carbon nanotube (CNT) Bucky-Paper (BP) composites with tuneable porosity and surface pore size. A BP is an entangled mesh non-woven like structure of nanotubes. Pure CNT BPs present both very high porosity (>90%) and specific surface area (>400 m2/g). Furthermore, their pore size is generally between 20–50 nm making them promising candidates for various membrane and separation applications. Both electro-plating and electroless plating techniques were used to plate different series of BPs and offered various degrees of success. Here we will report mainly on electroless plated gold/CNT composites. The benefit of this method resides in the versatility of the plating and the opportunity to tune both average pore size and porosity of the structure with a high degree of reproducibility. The CNT BPs were first oxidized by short UV/O3 treatment, followed by successive immersion in different plating solutions. The morphology and properties of these samples has been investigated and their performance in air permeation and gas adsorption will be reported. PMID:24957493

  11. Silica Transport, Deposition and Porosity Evolution in a Fracture : Insights from Hydrothermal Flow-through Experiments

    NASA Astrophysics Data System (ADS)

    Okamoto, A.; Yamada, R.; Saishu, H.; Tsuchiya, N.

    2014-12-01

    Geofluids contain a large amount of silica, which solubility changes depending on temperature and pressure. Ubiquitous occurrences of various silica deposits (quartz veins, silica sinter, scales) suggest that silica precipitation plays an important role on temporal and spatial variation of hydrological properties of the Earth's crusts. A pressure drop, for example, induced by seismicity, is one of the driving forces for silica precipitation within the crusts. In spite of the importance of silica depositions in fractures, how porosity and permeability evolution during silica precipitation is still poorly understood. In this study, we conducted the hydrothermal experiments for silica precipitation from supersaturated solutions in vapor (370˚C, 20 MPa) and supercritical (420 ˚C, 30 MPa) conditions with flow rate of 1 g/min. After the experiments, we analyzed the 3-D porosity structures by X-ray CT, and then by making thin section. We developed a tube-in-tube vessel, which is composed of main vessel (made of SUS316), and inner alumina tube (6 mm inner diameter), to make a horizontal flow path. We did not used rock/mineral substrates, and alumina balls (1 mm diameter) are closely packed in the inner tube. In both situations, a significant amount of silica deposited within a week, showing contrasting porosity structures between vapor and supercritical conditions. In vapor conditions, the precipitates are fine-grained quartz aggregate, and the most deposited at around 38 mm from the inlet. The pores were filled from the bottom to the top in the tube. In contrast, in the supercritical conditions, the precipitates are composites of amorphous silica and quartz; which accumulated around the alumina balls uniformly. Quartz grains are formed in amorphous silica layers, and the most porosity reduction occurred at around 25 mm from the inlet. A simple model of cellular automaton involving particle flow, adsorption, settling and deposition reveals that the relative magnitude of

  12. Positron annihilation characteristics in mesostructural silica films with various porosities

    SciTech Connect

    Xiong, Bangyun; Mao, Wenfeng; Tang, Xiuqin; He, Chunqing

    2014-03-07

    Porous silica films with various porosities were prepared via a sol-gel method using a nonionic amphiphilic triblock copolymer F127 as the structure-directing agent. Doppler broadening of positron annihilation radiation (DBAR) spectra were collected for the prepared films using a variable energy slow positron beam. Different linear relationships between positron annihilation line shape parameters S and W are found for the as-deposited films and calcined ones, indicative of the decomposition of the copolymer porogen in the as-deposited films upon calcination. This also reveals the variation of positron annihilation sites as a function of F127 loading or porosity. Strong correlations between positronium 3γ annihilation fraction, S parameter and porosity of the mesoporous silica films with isolated pores are obtained, which may provide a complementary method to determine closed porosities of mesoporous silica films by DBAR.

  13. Porosity-dependent fractal nature of the porous silicon surface

    SciTech Connect

    Rahmani, N.; Dariani, R. S.

    2015-07-15

    Porous silicon films with porosity ranging from 42% to 77% were fabricated by electrochemical anodization under different current density. We used atomic force microscopy and dynamic scaling theory for deriving the surface roughness profile and processing the topography of the porous silicon layers, respectively. We first compared the topography of bare silicon surface with porous silicon and then studied the effect of the porosity of porous silicon films on their scaling behavior by using their self-affinity nature. Our work demonstrated that silicon compared to the porous silicon films has the highest Hurst parameter, indicating that the formation of porous layer due to the anodization etching of silicon surface leads to an increase of its roughness. Fractal analysis revealed that the evolution of the nanocrystallites’ fractal dimension along with porosity. Also, we found that both interface width and Hurst parameter are affected by the increase of porosity.

  14. Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering

    PubMed Central

    Annabi, Nasim; Nichol, Jason W.; Zhong, Xia; Ji, Chengdong; Koshy, Sandeep; Khademhosseini, Ali

    2010-01-01

    Tissue engineering holds great promise for regeneration and repair of diseased tissues, making the development of tissue engineering scaffolds a topic of great interest in biomedical research. Because of their biocompatibility and similarities to native extracellular matrix, hydrogels have emerged as leading candidates for engineered tissue scaffolds. However, precise control of hydrogel properties, such as porosity, remains a challenge. Traditional techniques for creating bulk porosity in polymers have demonstrated success in hydrogels for tissue engineering; however, often the conditions are incompatible with direct cell encapsulation. Emerging technologies have demonstrated the ability to control porosity and the microarchitectural features in hydrogels, creating engineered tissues with structure and function similar to native tissues. In this review, we explore the various technologies for controlling the porosity and microarchitecture within hydrogels, and demonstrate successful applications of combining these techniques. PMID:20121414

  15. Positron annihilation characteristics in mesostructural silica films with various porosities

    NASA Astrophysics Data System (ADS)

    Xiong, Bangyun; Mao, Wenfeng; Tang, Xiuqin; He, Chunqing

    2014-03-01

    Porous silica films with various porosities were prepared via a sol-gel method using a nonionic amphiphilic triblock copolymer F127 as the structure-directing agent. Doppler broadening of positron annihilation radiation (DBAR) spectra were collected for the prepared films using a variable energy slow positron beam. Different linear relationships between positron annihilation line shape parameters S and W are found for the as-deposited films and calcined ones, indicative of the decomposition of the copolymer porogen in the as-deposited films upon calcination. This also reveals the variation of positron annihilation sites as a function of F127 loading or porosity. Strong correlations between positronium 3γ annihilation fraction, S parameter and porosity of the mesoporous silica films with isolated pores are obtained, which may provide a complementary method to determine closed porosities of mesoporous silica films by DBAR.

  16. High porosity of basal till at Burroughs glacier, southeastern Alaska

    SciTech Connect

    Ronnert, L.; Mickelson, D.M. )

    1992-09-01

    Debris-rich basal ice at Burroughs glacier, southeastern Alaska, has 60 vol% to 70 vol% debris. Recently deposited basal till exceeds 60 vol% sediment with 30% to almost 40% porosity. Where basal ice is very rich in debris, basal till is deposited through melt out with only slight compaction of the debris. Porosity this high in till is commonly associated with subglacially deforming and dilated sediment. However, the recently deposited basal melt-out till at Burroughs glacier has not been deformed after deposition, but has porosity values similar to tills elsewhere interpreted to be subglacially deforming and dilated in an unfrozen state. High porosity can occur in basal melt-out till deposited directly by basal melt out.

  17. Porosity evolution of upper Miocene reefs, Almeria Province, southern Spain

    USGS Publications Warehouse

    Armstrong, A.K.; Snavely, P.D.; Addicott, W.O.

    1980-01-01

    Sea cliffs 40 km east of Almeria, southeastern Spain, expose upper Miocene reefs and patch reefs of the Plomo formation. These reefs are formed of scleractinian corals, calcareous algae, and mollusks. The reef cores are as much as 65 m thick and several hundred meters wide. Fore-reef talus beds extend 1,300 m across and are 40 m thick. The reefs and reef breccias are composed of calcific dolomite. They lie on volcanic rocks that have a K-Ar date of 11.5 m.y. and in turn are overlain by the upper Miocene Vicar Formation. In the reef cores and fore-reef breccia beds, porosity is both primary and postdepositional. Primary porosity is of three types: (a) boring clam holes in the scleractinian coral heads, cemented reef rocks, and breccias; (b) intraparticle porosity within the corals, Halimeda plates, and vermetid worm tubes; and (c) interparticle porosity between bioclastic fragments and in the reef breccia. Postdepositional moldic porosity was formed by the solution of aragonitic material such as molluscan and coral fragments. The Plomo reef carbonate rocks have high porosity and permeability, and retain a great amount of depositional porosity. Pores range in size from a few micrometers to 30 cm. The extensive intercrystalline porosity and high permeability resulted from dolomitization of micritic matrix. Dolomite rhombs are between 10 and 30 μ across. More moldic porosity was formed by the dissolution of the calclte bioclasts. Some porosity reduction has occurred by incomplete and partial sparry calcite infilling of interparticular, moldic, and intercrystalline voids. The high porosity and permeability of these reefs make them important targets for petroleum exploration in the western Mediterranean off southern Spain. In these offshore areas in the subsurface the volcanic ridge and the Plomo reef complex are locally onlapped or overlapped by 350 m or more of Miocene(?) and Pliocene fine-grained sedimentary rocks. The possibility exists that the buried Plomo reef

  18. Influence of Weld Porosity on the Integrity of Marine Structures

    DTIC Science & Technology

    1989-02-01

    Bruce Mustain Mr. Alexander B . Stavov; U. S. MERCHANT MARINE ACADEMY NATIONAL ACADEMY OF SCIENCES Dr. C. B . Kim COMMITTEE ON MARINE STRUCTURE,, U. S...FIGURE 9(a). STRESS-LIFE PLOT SHOWING ACTUAL FATIGUE LIVES VERSUS PREDICTED FATIGUE LIVES OF WELDS CONTAINING POROSITY 32 FIGURE 9( b ). STRESS-LIFE PLOT...37 FIGURE 11. CLASS A AND CLASS B POROSITY CHART FOR 0.5 INCH (12.5 MM) THICK MATERIAL ....... ...................... ... 38 FIGURE 12

  19. Porosity evolution during experimental diagenesis of carbonates: influence of salinity

    NASA Astrophysics Data System (ADS)

    Neveux, Lucille; Grgic, Dragan; Carpentier, Cedric; Pironon, Jacques

    2015-04-01

    The existence of high quality (high porosity - high permeability) reservoirs in carbonated rocks at great depth highlights a paradox. Indeed, classical modeling of rock evolution during burial forecasts a strong decrease of porosity with depth, thus predicting a lack of economically interesting reservoirs under 4000 m. So how these reservoirs come to exist? The understanding of the way porosity is altered at great depth may indicate potential reservoir rocks. By which processes is porosity modified? To answer these questions, an experimental approach has been conducted, using a specifically designed apparatus that enable, in laboratory, the simulation of deeply buried reservoirs in situ conditions (high pressures and temperature as well as the circulation of fluids). The nature of carbonated rocks (bioclastic and oolitic) has been investigated as well as the nature of the percolating fluid (with and without NaCl). To characterize the evolution of the porosity and of the porous network, analysis via nanotomography, mercury intrusion porosimetry and specific surface area were used. The results obtained in this study show that the main diagenetic process of porosity loss is the pressure solution creep (PSC), reducing by at least three the initial porosity. PSC results in both dissolution and precipitation, processes that lead to a great modification of the rock porous network. This modification is more pronounced in the oolitic limestone than in the bioclastic one. The presence of NaCl in the fluid leads to a greater dissolution of carbonate matter but also to a precipitation of salt minerals partially blocking the porous network. The dataset obtained from these experiments shows the importance of the nature of the deposit rock but also of the nature of the percolating fluid. It can be concluded that pore fluid chemistry and, by consequence, its origin is of great importance in the study of porosity modification with depth.

  20. Modulus Dependence on Large Scale Porosity of Powder Metallurgy Steel

    NASA Astrophysics Data System (ADS)

    Allison, P. G.; Horstemeyer, M. F.; Brown, H. R.

    2012-07-01

    This article compares the existing theoretical expressions for the porosity dependence on elastic constants to experimental data for a commercially available material, FC-0205 powder metallurgy (PM) steel. The modulus of compression, tension, effective torsion, and ultrasound-based data at varying porosity levels are plotted graphically against the theoretical expressions. An equation by McAdam ( J. Iron Steel Inst. Lond., 1950, 168, p 346) was able to most accurately predict the experimental data with the adjustment of only one material constant.

  1. Porosity of porcine bladder acellular matrix: impact of ACM thickness.

    PubMed

    Farhat, Walid; Chen, Jun; Erdeljan, Petar; Shemtov, Oren; Courtman, David; Khoury, Antoine; Yeger, Herman

    2003-12-01

    The objectives of this study are to examine the porosity of bladder acellular matrix (ACM) using deionized (DI) water as the model fluid and dextran as the indicator macromolecule, and to correlate the porosity to the ACM thickness. Porcine urinary bladders from pigs weighing 20-50 kg were sequentially extracted in detergent containing solutions, and to modify the ACM thickness, stretched bladders were acellularized in the same manner. Luminal and abluminal ACM specimens were subjected to fixed static DI water pressure (10 cm); and water passing through the specimens was collected at specific time interval. While for the macromolecule porosity testing, the diffusion rate and direction of 10,000 MW fluoroescein-labeled dextrans across the ACM specimens mounted in Ussing's chambers were measured. Both experiments were repeated on the thin stretched ACM. In both ACM types, the fluid porosity in both directions did not decrease with increased test duration (3 h); in addition, the abluminal surface was more porous to fluid than the luminal surface. On the other hand, when comparing thin to thick ACM, the porosity in either direction was higher in the thick ACM. Macromolecule porosity, as measured by absorbance, was higher for the abluminal thick ACM than the luminal side, but this characteristic was reversed in the thin ACM. Comparing thin to thick ACM, the luminal side in the thin ACM was more porous to dextran than in the thick ACM, but this characteristic was reversed for the abluminal side. The porcine bladder ACM possesses directional porosity and acellularizing stretched urinary bladders may increase structural density and alter fluid and macromolecule porosity.

  2. Permeability-porosity relationships of subduction zone sediments

    USGS Publications Warehouse

    Gamage, K.; Screaton, E.; Bekins, B.; Aiello, I.

    2011-01-01

    Permeability-porosity relationships for sediments from the northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on sediment type, grain size distribution, and general mechanical and chemical compaction history. Greater correlation was observed between permeability and porosity in siliciclastic sediments, diatom oozes, and nannofossil chalks than in nannofossil oozes. For siliciclastic sediments, grouping of sediments by percentage of clay-sized material yields relationships that are generally consistent with results from other marine settings and suggests decreasing permeability as percentage of clay-sized material increases. Correction of measured porosities for smectite content improved the correlation of permeability-porosity relationships for siliciclastic sediments and diatom oozes. The relationship between permeability and porosity for diatom oozes is very similar to the relationship in siliciclastic sediments, and permeabilities of both sediment types are related to the amount of clay-size particles. In contrast, nannofossil oozes have higher permeability values by 1.5 orders of magnitude than siliciclastic sediments of the same porosity and show poor correlation between permeability and porosity. More indurated calcareous sediments, nannofossil chalks, overlap siliciclastic permeabilities at the lower end of their measured permeability range, suggesting similar consolidation patterns at depth. Thus, the lack of correlation between permeability and porosity for nannofossil oozes is likely related to variations in mechanical and chemical compaction at shallow depths. This study provides the foundation for a much-needed global database with fundamental properties that relate to permeability in marine settings. Further progress in delineating controls on permeability requires additional carefully documented permeability measurements on well-characterized samples. ?? 2010 Elsevier B.V.

  3. Properties of Bulk Sintered Silver As a Function of Porosity

    SciTech Connect

    Wereszczak, Andrew A; Vuono, Daniel J; Wang, Hsin; Ferber, Mattison K; Liang, Zhenxian

    2012-06-01

    This report summarizes a study where various properties of bulk-sintered silver were investigated over a range of porosity. This work was conducted within the National Transportation Research Center's Power Device Packaging project that is part of the DOE Vehicle Technologies Advanced Power Electronics and Electric Motors Program. Sintered silver, as an interconnect material in power electronics, inherently has porosity in its produced structure because of the way it is made. Therefore, interest existed in this study to examine if that porosity affected electrical properties, thermal properties, and mechanical properties because any dependencies could affect the intended function (e.g., thermal transfer, mechanical stress relief, etc.) or reliability of that interconnect layer and alter how its performance is modeled. Disks of bulk-sintered silver were fabricated using different starting silver pastes and different sintering conditions to promote different amounts of porosity. Test coupons were harvested out of the disks to measure electrical resistivity and electrical conductivity, thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and yield stress. The authors fully recognize that the microstructure of processed bulk silver coupons may indeed not be identical to the microstructure produced in thin (20-50 microns) layers of sintered silver. However, measuring these same properties with such a thin actual structure is very difficult, requires very specialized specimen preparation and unique testing instrumentation, is expensive, and has experimental shortfalls of its own, so the authors concluded that the herein measured responses using processed bulk sintered silver coupons would be sufficient to determine acceptable values of those properties. Almost all the investigated properties of bulk sintered silver changed with porosity content within a range of 3-38% porosity. Electrical resistivity, electrical conductivity, thermal

  4. Oil fill procesure for seismic marine streamer

    SciTech Connect

    Buckles, J.J.

    1990-08-21

    This patent describes a method for improving signal quality in urethane foam mounts utilized on hydrophones in conjunction with a seismic streamer. It comprises: purging a urethane foam mount with a fluid miscible with air and hydrocarbonaceous liquid having a selected density which liquid is used to dampen noise in a hydrophone where the fluid is a member selected from the group consisting of carbon dioxide, fluorocarbons, C{sub 1}{minus}C{sub 4} hydrocarbons, and mixtures thereof which member alone substantially displaces air from the streamer; and thereafter filling the seismic streamer with the hydrocarbonaceous liquid which mixes with the fluid and substantially retains the density of the liquid thereby maintaining neutral buoyancy of the streamer, substantially isolating the hydrophones from noise, and improving signal quality.

  5. Effect of porosity and the inlet heat transfer fluid temperature variation on the performance of cool thermal energy storage system

    NASA Astrophysics Data System (ADS)

    Cheralathan, M.; Velraj, R.; Renganarayanan, S.

    2007-06-01

    This paper discusses the results of numerical and experimental study of an encapsulated cool thermal energy storage system. The storage system is a cylindrical storage tank filled with phase change material encapsulated in spherical container, placed in a refrigeration loop. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid and the phase change material at any axial location during the charging period. The present analysis aims at studying the influence of the inlet heat transfer fluid temperature and porosity on system performance. An experimental setup was designed and constructed to conduct the experiments. The results of the model were validated by comparison with experimental results of temperature profiles for different inlet heat transfer fluid temperatures and porosity. The results are in good agreement with the experimental results. The results reported are much useful for designing cool thermal energy storage systems.

  6. Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control

    PubMed Central

    Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

    2014-01-01

    Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part’s porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented. PMID:26601041

  7. Bone porosity and longevity in early medieval Southern Croatia.

    PubMed

    Bečić, Kristijan; Jandrić Bečić, Darija; Definis-Gojanović, Marija; Zekić Tomaš, Sandra; Anterić, Ivana; Bašić, Zeljana

    2014-03-01

    Porosity of the skull and skeletal remains, especially of the orbital roof, are one of the most frequent pathological findings on ancient human skeletal remains. There are several presumed causes of this condition and anthropologists consider skull porosities as a marker of physical and nutritional stress. A total of 115 graves were discovered at the early-medieval graveyard near Zadar (Croatia) that contained 128 partially preserved skeletons. Average estimated age at death was 37.2 ± 12.6 years for men, 31.9 ± 13.9 for women, and 5.3 ± 3.6 years for subadults. Pathological bone porosity was analysed. Cribra orbitalia was observed on 21 skulls (28.7%), signs of temporal porosity were noticed on six skulls and signs of subperiosteal bleeding on three skulls. Nineteen skulls had bone porosities in other areas. There was a significant difference (p = 0.039) in achieved age of adults with and without cribra orbitalia as those with cribra orbitalia lived on average 8.1 years longer. The bone porosity was probably caused by malnutrition that might have had a beneficial effect on longevity of adults, similar to effects of restricted food intake on extending lifespan through epigenetic signatures influencing gene expression.

  8. Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control.

    PubMed

    Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

    2014-01-01

    Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented.

  9. Double porosity modeling in elastic wave propagation for reservoir characterization

    SciTech Connect

    Berryman, J. G., LLNL

    1998-06-01

    Phenomenological equations for the poroelastic behavior of a double porosity medium have been formulated and the coefficients in these linear equations identified. The generalization from a single porosity model increases the number of independent coefficients from three to six for an isotropic applied stress. In a quasistatic analysis, the physical interpretations are based upon considerations of extremes in both spatial and temporal scales. The limit of very short times is the one most relevant for wave propagation, and in this case both matrix porosity and fractures behave in an undrained fashion. For the very long times more relevant for reservoir drawdown,the double porosity medium behaves as an equivalent single porosity medium At the macroscopic spatial level, the pertinent parameters (such as the total compressibility) may be determined by appropriate field tests. At the mesoscopic scale pertinent parameters of the rock matrix can be determined directly through laboratory measurements on core, and the compressibility can be measured for a single fracture. We show explicitly how to generalize the quasistatic results to incorporate wave propagation effects and how effects that are usually attributed to squirt flow under partially saturated conditions can be explained alternatively in terms of the double-porosity model. The result is therefore a theory that generalizes, but is completely consistent with, Biot`s theory of poroelasticity and is valid for analysis of elastic wave data from highly fractured reservoirs.

  10. Integrated design of castings: effect of porosity on mechanical performance

    NASA Astrophysics Data System (ADS)

    Hardin, R. A.; Beckermann, C.

    2012-07-01

    Porosity can significantly reduce the strength and durability of castings in service. An integrated design approach has been developed where casting simulation is combined with mechanical performance simulations. Predictions of the porosity distribution from the casting process simulation are transferred to and used in stress and fatigue life simulations. Thus, the effect of casting quality on service performance can be evaluated. Results of a study are presented where the measured porosity distribution in cast steel specimens is transferred to an elasto-plastic finite-element stress analysis model. Methods are developed to locally reduce the mechanical properties according to the porosity present, without having to resolve individual pores. Plastic deformation is modeled using porous metal plasticity theory. The predictions are compared to tensile measurements performed on the specimens. The complex deformations and the reductions in the ductility of the specimens due to porosity are predicted well. The predicted stresses are transferred to a fatigue analysis code that takes the porosity distribution into account as well. The measured and predicted fatigue lives are also in good agreement. Finally, the results of a case study are presented that illustrate the utility of the present integrated approach in optimizing the design of a steel casting.

  11. Porosity of Bleb Capsule declines rapidly with Fluid Challenge

    PubMed Central

    Pandav, Surinder S; Ross, Craig M; Thattaruthody, Faisal; Nada, Ritambhra; Singh, Nirbhai; Gautam, Natasha; Beirne, Stephen; Wallace, Gordon G; Sherwood, Mark B; Crowston, Jonathan G

    2016-01-01

    Introduction The porosity of the fibrous capsule around a glaucoma drainage device (GDD) may be the most important functional attribute. The factors that determine capsular porosity are not well understood. Failed GDD surgeries are usually associated with thick impervious capsules and components of aqueous have been implicated in this process. Purpose In this study, we interrogated the effect of passage of nonaqueous fluid on capsular porosity in mature (but aqueous naïve) blebs in a previously reported GDD model (the “Center for Eye Research Australia Implant”). Materials and methods The study was performed at two centers using 17 New Zealand White (NZW) rabbits. An experimental GDD was implanted into the subconjunctival space but without connection to the anterior chamber. After 28 days, balanced salt solution (BSS) was passed through the implant for 30 to 40 minutes at 12 mm Hg. Capsular porosity was measured as flow (μL/min) at a constant pressure. Porosity of the capsule was retested at 3 and 6 days. Results There was a marked reduction in capsular porosity within 3 days of exposure to BSS (fluid challenge). Even though the baseline porosity was significantly different in the two groups (3.00 ± 0.5 μL/min and 29.67 ± 12.12 μL/min, p < 0.001), the effect of passage of BSS was similar. Capsular porosity fell by approximately 80% in both groups from baseline after single BSS challenge. Capsular thickness was significantly less in Advanced Eye Center (AEC) rabbits at baseline. There was no change in the capsular thickness before and after single fluid challenge. Conclusion Passage of BSS at physiological pressures for under 40 minutes caused marked reduction in the porosity of the fibrous capsule within 3 days. This was not associated with any significant thickening of the fibrous capsule within this time frame. How to cite this article Pandav SS, Ross CM, Thattaruthody F, Nada R, Singh N, Gautam N, Beirne S, Wallace GG, Sherwood MB, Crowston JG, Coote M

  12. Permeability Evolution and the Mechanisms of Porosity Change (Invited)

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Gribbin, J. L.; Tivey, M. K.

    2013-12-01

    Understanding subsurface fluid flow is of critical importance to such geological and engineering applications as faulting mechanics, hydrothermal venting and resource recovery. Mechanical, chemical and thermal loads can significantly alter microscopic pore geometry and thus affect macroscopic permeability. Recently, we measured the permeability and porosity of massive anhydrite deposits recovered from various seafloor hydrothermal vent fields. Together, these deposits comprise anhydrite samples that have undergone different stages of formation. For anhydrite samples with porosities greater than 5%, the dependence of permeability to porosity change is best characterized by a power-law relationship with an exponent n~9. At porosities less than 5%, a much gentler trend of n~1 is observed. These permeability-porosity relationships (PPRs) in anhydrite deposits are in stark contrast to those of Fontainebleau sandstone, a quartz arenite with various degrees of quartz cementation. Fontainebleau sandstone shows a power-law dependence of PPR with an exponent of n~3 for samples with porosities greater than 7%, and a much steeper trend of n~8 at low porosities [Bourbie and Zinszner, 1985]. Microstructural analysis and numerical models suggest that the significant loss in pore connectivity below 7% is responsible for the steeper PPR trend in Fontainebleau sandstone [Zhu et al., 1995]. In anhydrite deposits, petrographic analyses show evidence for both dissolution and precipitation, consistent with the observed PPRs resulting from pore-size controlled solubility. Precipitation of anhydrite takes place preferentially in large pores within the anhydrite deposits, with precipitation limited in small pores, which is proposed to be due to the change in interfacial energy of the growing crystal (e.g., as described by Emmanuel and Ague [2009]). With abundant large voids in high porosity anhydrite samples, the growth of sulfates would result in a drastic loss of pore connectivity and

  13. Electrical Transport Through Micro Porous Track Etch Membranes of same Porosity

    NASA Astrophysics Data System (ADS)

    Garg, Ravish; Kumar, Vijay; Kumar, Dinesh; Chakarvarti, S. K.

    2012-12-01

    Porosity, pore size and thickness of membrane are vital factors to influence the transport phenomena through micro porous track etch membranes (TEMs) and affect the various applications like separations, drug release, flow control, bio-sensing and cell size detection etc. based on transport process. Therefore, a better understanding of transport mechanism through TEMs is required for new applications in various thrust areas like biomedical devices and packaging of foods and drugs. Transport studies of electrolytic solutions of potassium chloride, through porous polycarbonate TEMS having cylindrical pores of size 0.2 μm and 0.4 μm with same porosity of 15%, have been carried out using an electrochemical cell. In this technique, the etched filter is sandwiched between two compartments of cell in such a way that the TEM acts as a membrane separating the cell into two chambers. The two chambers are then filled with electrolyte solution (KCl in distilled water). The current voltage characteristics have been drawn by stepping the voltage ranging 0 to 10 V using Keithley 2400 Series Source Measurement Unit. The results indicate that rate of ion transport through cylindrical pores although is independent of pore size of TEMs of same porosity but there seems to be effect of TEM aperture size exposed to the electrolyte used in conducting cell on ion transport magnitude. From the experimental studies, a large deviation in the conduction through TEMs was observed when compared with theoretical consideration which led to the need for modification in the applicability of simple Ohm's law to the conduction through TEMs. It is found that ion transport increases with increase in area of aperture of TEM but much lower than the expected theoretically value.

  14. Fabrication of uniform porosity, all-porous-silicon microstructures and stress/stress gradient control

    NASA Astrophysics Data System (ADS)

    Sun, Xiao; Parish, Giacinta; Keating, Adrian

    2017-04-01

    All-mesoporous silicon microstructures were released with standard micromachining processes. The extremely high porosity of the films allows control of the mechanical properties as well as providing a platform material for devices with extremely large surface area. To pattern and release devices from these highly porous structural layers, pore filling, photoresist mask adhesion and electropolishing techniques were developed. The internal stress of porous silicon was characterized under repeated thermal annealing and HF immersion treatments, allowing a stable, slightly tensile stress of 2.0  ±  0.4 MPa to be achieved. A method to independently control the stress gradient induced curvature in the porous MEMS devices was developed, which achieved released PS structures that were flat to within 78 nm over a range of 100 µm. This is the first time that fully released, stress gradient adjusted all-mesoporous-silicon structures have been reported.

  15. Failure mechanisms of nano-silicon anodes upon cycling: an electrode porosity evolution model.

    PubMed

    Radvanyi, Etienne; Porcher, Willy; De Vito, Eric; Montani, Alexandre; Franger, Sylvain; Jouanneau Si Larbi, Séverine

    2014-08-28

    With a specific capacity of 3600 mA h g(-1), silicon is a promising anode active material for Li-ion batteries (LIBs). However, because of the huge volume changes undergone by Si particles upon (de)alloying with lithium, Si electrodes suffer from rapid capacity fading. A deep understanding of the associated failure mechanisms is necessary to improve these electrochemical performances. To reach this goal, we investigate here nano-Si based electrodes by several characterization techniques. Thanks to all these techniques, many aspects, such as the behaviour of the active material or the solid electrolyte interphase (SEI) and the lithiation mechanisms, are studied upon cycling. A clear picture of the failure mechanisms of nano-Si based electrodes is provided. In particular, by combining Hg analyses, SEM observations of electrode cross-sections, and EIS measurements, we follow the evolution of the porosity within the electrode. For the first time, our results clearly show a real dynamic of the pore size distribution: the first cycles lead to the formation of a micrometric porosity which is not present initially. During the following cycles, these large pores are progressively filled up with SEI products which form continuously at the Si particle surface. Thus, from the 50th cycle, Li(+) ion diffusion is dramatically hindered leading to a strongly heterogeneous lithiation of the electrode and a rapid capacity fading.

  16. Effects of grain size and porosity on strength of Li2TiO3 tritium breeding pebbles and its grain growth behavior

    NASA Astrophysics Data System (ADS)

    Xiang, Maoqiao; Zhang, Yingchun; Zhang, Yun; Wang, Chaofu; Liu, Wei; Yu, Yonghong

    2016-12-01

    Tons of Li2TiO3 tritium breeding pebbles will be filled in the blanket for obtaining tritium fuel. In this work, isothermal sintering was carried out to study the grain growth behavior of the Li2TiO3 pebbles fabricated by agarose method. The grain growth exponent (n) and the activation energy (Q) calculated by the phenomenological kinetic equation were 2 and 435.65 kJ/mol, respectively. The grain growth was controlled by vapor transport (p = 2S/r). In addition, effects of porosity and grain-size on the strength of Li2TiO3 pebbles were investigated. The strength was affected by the grain size and the porosity of Li2TiO3 pebbles, and high strength (about 72 MPa) depended partly on achieving the optimum balance between the porosity (about 10%) and grain size (about 2 μm).

  17. Method and apparatus for filling thermal insulating systems

    DOEpatents

    Arasteh, D.K.

    1992-01-14

    A method for filling insulated glazing units is disclosed. The method utilizes a vacuum chamber in which the insulated glazing units are placed. The insulated glazing units and vacuum chamber are evacuated simultaneously. The units are then refilled with a low conductance gas such as Krypton while the chamber is simultaneously refilled with air. 3 figs.

  18. Method and apparatus for filling thermal insulating systems

    DOEpatents

    Arasteh, Dariush K.

    1992-01-01

    A method for filling insulated glazing units is disclosed. The method utilizes a vacuum chamber in which the insulated glazing units are placed. The insulated glazing units and vacuum chamber are evacuated simultaneously. The units are then refilled with a low conductance gas such as Krypton while the chamber is simultaneously refilled with air.

  19. Prevention of Porosity Formation and Other Effects of Gaseous Elements in Iron Castings

    SciTech Connect

    Albany Research Center

    2005-04-01

    Iron foundries have observed porosity primarily as interdendritic porosity in large freezing range alloys such as Ni-Hard I and hypoeutectic high Cr alloys or pinholes and fissure defects in gray and ductile irons. For most iron foundries, porosity problems occur sporadically, but even occasional outbreaks can be costly since even a very small amount of porosity can significantly reduce the mechanical properties of the castings. As a result when porosity is detected, the castings are scrapped and remelted, or when the porosity is undetected, defective parts are shipped to the consumer. Neither case is desirable. This project was designed to examine various factors contributing to the porosity formation in iron castings. Factors such as solubility of gases in liquid and solid iron alloys, surface tension of liquid iron alloys, and permeability of dendritic structures were investigated in terms of their effect on the porosity formation. A method was developed to predict how much nitrogen the molten alloy picks up from air after a given amount of holding time for a given melting practice. It was shown that small batches of iron melts in an induction furnace can end up with very high concentration of nitrogen (near solubility limit). Surface tension of liquid iron alloys was measured as a function of temperature. Effect of minor additions of S, Ti, and Al on the surface tension of liquid iron alloys was investigated. Up to 18% change in surface tension was detected by minor element additions. This translates to the same amount of change in gas pressure required in a bubble of a given size to keep the bubble stable. A new method was developed to measure the permeability of dendritic structures in situ. The innovative aspect of these experiments, with respect to previous interdendritic permeability measurements, was the fact that the dendritic structure was allowed to form in situ and was not cooled and re-heated for permeability tests. A permeability model was developed

  20. Field determination of vertical permeability to air in the unsaturated zone

    USGS Publications Warehouse

    Weeks, Edwin P.

    1978-01-01

    The vertical permeability to air of layered materials in the unsaturated zone may be determined from air pressure data obtained at depth during a period when air pressure is changing at land surface. Such data may be obtained by monitoring barometric pressure with a microbarograph or surveying altimeter and simultaneously measuring down-hole pneumatic head differences in specially constructed piezometers. These data, coupled with air-filled porosity data from other sources, may be compared with the results of electric-analog or numerical solution of the one-dimensional diffusion equation to make a trial-and-error determination of the air permeability for each layer. The permeabilities to air may in turn be converted to equivalent hydraulic conductivity values if the materials are well drained, are permeable enough that the Klinkenberg effect is small, and are structurally unaffected by wetting. The method offers potential advantages over present methods to evaluate sites for artificial recharge by spreading; to evaluate ground-water pollution hazards from feedlots, sanitary landfills , and land irrigated with sewage effluent; and to evaluate sites for temporary storage of gas in the unsaturated zone. (Woodard-USGS)

  1. Porosity investigation of compacted bentonite using XRD profile modeling

    NASA Astrophysics Data System (ADS)

    Holmboe, Michael; Wold, Susanna; Jonsson, Mats

    2012-02-01

    Many countries intend to use compacted bentonite as a barrier in their deep geological repositories for nuclear waste. In order to describe and predict hydraulic conductivity or radionuclide transport through the bentonite barrier, fundamental understanding of the microstructure of compacted bentonite is needed. This study examined the interlayer swelling and overall microstructure of Wyoming Bentonite MX-80 and the corresponding homo-ionic Na + and Ca 2 + forms, using XRD with samples saturated under confined swelling conditions and free swelling conditions. For the samples saturated under confined conditions, the interparticle, or so-called free or external porosity was estimated by comparing the experimental interlayer distances obtained from one-dimensional XRD profile fitting against the maximum interlayer distances possible for the corresponding water content. The results showed that interlayer porosity dominated total porosity, irrespective of water content, and that the interparticle porosity was lower than previously reported in the literature. At compactions relevant for the saturated bentonite barrier (1.4-1.8 g/cm 3), the interparticle porosity was estimated to ≤ 3%.

  2. Testing Mercury Porosimetry with 3D Printed Porosity Models

    NASA Astrophysics Data System (ADS)

    Hasiuk, F.; Ewing, R. P.; Hu, Q.

    2014-12-01

    Mercury intrusion porosimetry is one of the most widely used techniques to study the porous nature of a geological and man-made materials. In the geosciences, it is commonly used to describe petroleum reservoir and seal rocks as well as to grade aggregates for the design of asphalt and portland cement concretes. It's wide utility stems from its ability to characterize a wide range of pore throat sizes (from nanometers to around a millimeter). The fundamental physical model underlying mercury intrusion porosimetry, the Washburn Equation, is based on the assumption that rock porosity can be described as a bundle of cylindrical tubes. 3D printing technology, also known as rapid prototyping, allows the construction of intricate and accurate models, exactly what is required to build models of rock porosity. We evaluate the applicability of the Washburn Equation by comparing properties (like porosity, pore and pore throat size distribution, and surface area) computed on digital porosity models (built from CT data, CAD designs, or periodic geometries) to properties measured via mercury intrusion porosimetry on 3D printed versions of the same digital porosity models.

  3. Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures

    SciTech Connect

    Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

    2009-09-27

    Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

  4. Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures

    SciTech Connect

    Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

    2011-02-14

    Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

  5. Procedure for Uranium-Molybdenum Density Measurements and Porosity Determination

    SciTech Connect

    Prabhakaran, Ramprashad; Devaraj, Arun; Joshi, Vineet V.; Lavender, Curt A.

    2016-08-13

    The purpose of this document is to provide guidelines for preparing uranium-molybdenum (U-Mo) specimens, performing density measurements, and computing sample porosity. Typical specimens (solids) will be sheared to small rectangular foils, disks, or pieces of metal. A mass balance, solid density determination kit, and a liquid of known density will be used to determine the density of U-Mo specimens using the Archimedes principle. A standard test weight of known density would be used to verify proper operation of the system. By measuring the density of a U-Mo sample, it is possible to determine its porosity.

  6. Tensile strengths and porosities of solar system primitive bodies

    NASA Astrophysics Data System (ADS)

    Trigo-Rodriguez, J. M.; Llorca, J.; Blum, J.

    Recent measurements of asteroid bulk densities suggest that rubble-pile asteroids with typical porosities of 30 to 50% may be common (Britt et al., 2006). However, the presence of such objects doesn't mean necessarily that the initial porosity had been preserved (Kerridge, 1993). In fact, the fluffy aggregates produced in laboratory experiments that we expect to be representative of the oldest protoplanetary disk materials, exhibit even higher porosities (Blum et al., 2006). Recent results confirm that primitive meteorites (like e.g. CM carbonaceous chondrites) are compacted samples of the nebula matter exhibiting different density and porosity that their precursors materials (Trigo-Rodríguez et al., 2006). Consequently, aqueous alteration, brecciation, and impact-induced metamorphism make very unlikely to find pristine bodies between the asteroidal population. However, there is clear evidence for the existence of high-porosity bodies between the C-type asteroids like e.g. Mathilde (Housen et al., 1999) or the Tagish Lake parent body (Brown et al., 2002). Although extensive post-accretionary processing of meteorite parent bodies can produce high degrees of porosity, only the most pristine ones seem to preserve more than 50% of porosity. Consequently, we should look for these low strength bodies among the C-type asteroids, or very especially in some unprocessed comets that continue being representative of the precursor materials. Recent suggestion that CI1 chondrites are originated from comets should be studied in this context (Gounelle et al., 2006). Particularly, we think that studies of the porosity and strength of primitive meteorites would provide valuable clues on the origin and nature of their parent bodies. REFERENCES Blum J., R. Schräpler, B.J.R. Davidson and J.M. Trigo-Rodríguez (2006) Astroph. J., submitted. Britt D.T., G.J. Consolmagno, and W.J. Merline (2006) Lunar Planet. Sci. Conf. Abstract #2214. Brown, P. G., D. O. Revelle, E. Tagliaferri, and A

  7. PALS and DSC study of nanopores partially filled by hexadecane

    NASA Astrophysics Data System (ADS)

    Šauša, O.; Illeková, E.; Krištiak, J.; Berek, D.; Macová, E.

    2013-06-01

    The controlled porosity glasses (CPG) filled with various amount of hexadecane (HXD) in nanopores were studied both by the positron annihilation lifetime spectroscopy (PALS) and the differential scanning calorimetry (DSC) methods. Two types of CPG matrices were used with average pore sizes 12.6 and 22.2 nm. The PALS measurements showed, that when the process of large pores filling by HXD has started, the long o-Ps lifetime went down to HXD o-Ps lifetime about 3ns [1]. DSC measurements at partially filled nanopores showed always two crystallization peaks [2]. Their positions depended on average pore size of matrix. Third crystallization peak was identified in overfilled samples (only short o-Ps lifetimes were present) and their position in temperature scale was the same as for the bulk HXD peak. The latter peak was independent of the average pore size of matrices. This fact confirms the assumption that processes studied by PALS with the samples that contained smaller amount of HXD in CPG occured inside of nanopores of the matrix.

  8. Thermal management improvement of an air-cooled high-power lithium-ion battery by embedding metal foam

    NASA Astrophysics Data System (ADS)

    Mohammadian, Shahabeddin K.; Rassoulinejad-Mousavi, Seyed Moein; Zhang, Yuwen

    2015-11-01

    Effect of embedding aluminum porous metal foam inside the flow channels of an air-cooled Li-ion battery module was studied to improve its thermal management. Four different cases of metal foam insert were examined using three-dimensional transient numerical simulations. The effects of permeability and porosity of the porous medium as well as state of charge were investigated on the standard deviation of the temperature field and maximum temperature inside the battery in all four cases. Compared to the case of no porous insert, embedding aluminum metal foam in the air flow channel significantly improved the thermal management of Li-ion battery cell. The results also indicated that, decreasing the porosity of the porous structure decreases both standard deviation of the temperature field and maximum temperature inside the battery. Moreover, increasing the permeability of the metal foam drops the maximum temperature inside the battery while decreasing this property leads to improving the temperature uniformity. Our results suggested that, among the all studied cases, desirable temperature uniformity and maximum temperature were achieved when two-third and the entire air flow channel is filled with aluminum metal foam, respectively.

  9. Relationship between regolith particle size and porosity on small bodies

    NASA Astrophysics Data System (ADS)

    Kiuchi, M.; Nakamura, A.

    2014-07-01

    Small planetary bodies are covered by a particle layer called the regolith. The particle size and porosity of the regolith surface of the small bodies are important physical properties. The responses of the surface to solar irradiation depend on the particle size and porosity. The particle size and porosity have influences on the dynamic responses of the surface, such as cratering efficiency. In previous studies, these two quantities were measured or estimated by various methods. Here we propose a semi-empirical relationship between the particle size and porosity for small bodies' surfaces. An empirical relationship between the porosity of granular materials in loose packing state under 1G and the ratio of the magnitudes of the interparticle force and gravity which act on a particle was presented in a previous study [1]. In this study, we assume that the van der Waals force F_{V} is predominant in the interparticle forces and adopt a model formula [2] which is different from that adopted in the previous study [1]: F_{V} = {AS^{2}}/{48Ω ^{2}}r, where A is the Hamaker constant, r is the particle radius, Ω is the diameter of an O^{-2} ion, and S is the cleanliness ratio which shows the smallness of a number of the adsorbate molecules [2]. It was shown that the cleanliness ratio S is approximately 0.1 on the Earth, and is almost unity in the interplanetary space. In addition to the data of the several previous studies, our own measurement result for micron-sized fly-ash particles in atmospheric conditions is used in the present analysis. We calculate F_{V} using Eq. (1), and obtain a relationship between porosity and the ratio R_{F} = F_{V}/F_{g}, where F_{g} is gravity. An empirical formula used in the previous study [1], p = p_{0}+(1-p_{0})exp(-m{R_{F}}^{-n}), is applied to fit the data, where p is the porosity and p_{0}, m and n are constants. We assume that p_{0} is 0.36. By substituting Eq. (1) to Eq. 2, we obtain p = p_{0}+(1-p_{0})exp {-m({AS^{2}}/{64πΩ ^{2

  10. Porosity trends of the Lower Cretaceous J Sandstone, Denver Basin, Colorado

    USGS Publications Warehouse

    Schmoker, J.W.; Higley, D.K.

    1991-01-01

    The petrographic factors that most affect J sandstone porosity variability at a given level of thermal maturity are carbonate cementation and clay content. Carbonate cement, where present, reduces porosity. If previously more widespread, carbonate cement could also introduce porosity heterogeneity by temporarily preserving the pore network relative to uncemented intervals. Abundant detrital and authigenic clay reduces porosity by occupying pores. Low clay content indirectly reduces porosity because the inhibiting effects of clay upon quartz cementation and pressure solution are largely absent. -from Authors

  11. Soil atmosphere exchange of Carbonyl Sulfide (COS) regulated by diffusivity depending on water-filled pore space

    NASA Astrophysics Data System (ADS)

    van Diest, H.; Kesselmeier, J.

    2007-10-01

    The exchange of carbonyl sulfide (COS) between soil and the atmosphere was investigated for three arable soils from Germany, China and Finland and one forest soil from Siberia for parameterization in the relation to ambient carbonyl sulfide (COS) concentration, soil water content (WC) and air temperature. All investigated soils acted as significant sinks for COS. A clear and distinct uptake optimum was found for the German, Chinese, Finnish and Siberian soils at 11.5%, 9%, 11.5%, and 9% soil WC, respectively, indicating that the soil WC acts as an important biological and physical parameter for characterizing the exchange of COS between soils and the atmosphere. Different optima of deposition velocities (Vd) as observed for the Chinese, Finnish and Siberian boreal soil types in relation to their soil WC, aligned at 19% in relation to the water-filled pore space (WFPS), indicating the dominating role of gas diffusion. This interpretation was supported by the linear correlation between Vd and bulk density. We suggest that the uptake of COS depends on the diffusivity dominated by WFPS, a parameter depending on soil WC, soil structure and porosity of the soil.

  12. Soil atmosphere exchange of carbonyl sulfide (COS) regulated by diffusivity depending on water-filled pore space

    NASA Astrophysics Data System (ADS)

    van Diest, H.; Kesselmeier, J.

    2008-04-01

    The exchange of carbonyl sulfide (COS) between soil and the atmosphere was investigated for three arable soils from Germany, China and Finland and one forest soil from Siberia for parameterization in the relation to ambient carbonyl sulfide (COS) concentration, soil water content (WC) and air temperature. All investigated soils acted as sinks for COS. A clear and distinct uptake optimum was found for the German, Chinese, Finnish and Siberian soils at 11.5%, 9%, 11.5%, and 9% soil WC, respectively, indicating that the soil WC acts as an important biological and physical parameter for characterizing the exchange of COS between soils and the atmosphere. Different optima of deposition velocities (Vd) as observed for the Chinese, Finnish and Siberian boreal soil types in relation to their soil WC, aligned at 19% in relation to the water-filled pore space (WFPS), indicating the dominating role of gas diffusion. This interpretation was supported by the linear correlation between Vd and bulk density. We suggest that the uptake of COS depends on the diffusivity dominated by WFPS, a parameter depending on soil WC, soil structure and porosity of the soil.

  13. Study of oil sorption behavior of filled and structured fiber assemblies made from polypropylene, kapok and milkweed fibers.

    PubMed

    Rengasamy, R S; Das, Dipayan; Karan, C Praba

    2011-02-15

    This article reports on oil sorption behavior of fiber assemblies made up of single natural and synthetic fibers as well as blend of natural and synthetic fibers when tested with high density oil and diesel oil. A series of filled fiber assemblies were prepared from 100% polypropylene, kapok, and milkweed fibers and another series of bonded structured fiber assemblies were prepared from a 70/30 blend of kapok and polypropylene fibers and a 70/30 blend of milkweed and polypropylene fibers. It was observed that the porosity of the fiber assemblies played a very important role in determining its oil sorption capacity. The polypropylene fiber assembly exhibited the highest sorption capacity (g/g) followed by the kapok and milkweed fiber assemblies at porosity <0.98. At higher porosities (above 0.98), polypropylene filled fiber assembly has poor sorption capacity due to large sized inter fiber pore. The kapok and milkweed fibers have intra fiber porosities of 0.81 and 0.83, respectively. All the fiber assemblies showed higher oil sorption capacity with the high density oil as compared to the diesel oil. As the kapok and milkweed fiber have low cellulose content, hence their slow degradation is an advantage in fresh and marine water applications. The good sorption capacity of kapok and milkweed fiber assemblies along with their bio-degradable nature offer great scope for structuring them into fiber assemblies with large porosity and uniform pores to have efficient oil sorbents.

  14. Filling carbon nanotubes with particles.

    PubMed

    Kim, Byong M; Qian, Shizhi; Bau, Haim H

    2005-05-01

    The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.

  15. Paleovalley fills: Trunk vs. tributary

    USGS Publications Warehouse

    Kvale, E.P.; Archer, A.W.

    2007-01-01

    A late Mississippian-early Pennsylvanian eustatic sea level drop resulted in a complex lowstand drainage network being eroded across the Illinois Basin in the eastern United States. This drainage system was filled during the early part of the Pennsylvanian. Distinct differences can be recognized between the trunk and tributary paleovalley fills. Fills preserved within the trunk systems tend to be fluvially dominated and consist of bed-load deposits of coarse- to medium-grained sandstone and conglomerate. Conversely, the incised valleys of tributary systems tend to be filled with dark mudstone, thinly interbedded sandstones, and mudstones and siltstones. These finer grained facies exhibit marine influences manifested by tidal rhythmites, certain traces fossils, and macro- and microfauna. Examples of tributary and trunk systems, separated by no more than 7 km (4.3 mi) along strike, exhibit these styles of highly contrasting fills. Useful analogs for understanding this Pennsylvanian system include the Quaternary glacial sluiceways present in the lower Ohio, White, and Wabash river valleys of Indiana (United States) and the modern Amazon River (Brazil). Both the Amazon River and the Quaternary rivers of Indiana have (or had) trunk rivers that are (were) dominated by large quantities of bed load relative to their tributaries. The trunk valley systems of these analogs aggraded much more rapidly than their tributary valleys, which evolved into lakes because depositional rates along the trunk are (were) so high that the mouths of the tributaries have been dammed by bed-load deposits. These Holocene systems illustrate that sediment yields can significantly influence the nature of fill successions within incised valleys independent of rates of sea level changes or proximity to highstand coastlines. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

  16. Weaving and bonding method to prevent warp and fill distortion

    NASA Technical Reports Server (NTRS)

    Farley, Gary L. (Inventor)

    1997-01-01

    A method to prevent fiber distortion in textile materials employed in a modified weaving process. In a first embodiment, a tacifier in powder form is applied to the yarn and melted while on the fabric. Cool air is then supplied after the tacifier has melted to expedite the solidification of the tacifier. In a second embodiment, a solution form of a tacifier is used by dissolving the tacifier into a solvent that has a high evaporation rate. The solution is then sprayed onto the fabric or fill yarn as each fill yarn is inserted into a shed of the fabric. A third embodiment applies the tacifier in a liquid form that has not been dissolved in a solvent. That is, the tacifier is melted and is sprayed as a liquid onto the fabric or fill yarn as it is being extracted from a fill yarn spool prior to the fill yarn being inserted into the shed of the fabric. A fourth embodiment employs adhesive yarns contained as an integral part of the warp or fill yarn. Additional tacifier material is not required because a matrix is used as the tacifier. The matrix is then locally melted using heating elements on clamping bars or take-up rollers, is cooled, if necessary, and solidified.

  17. Predicting pore pressure and porosity from VSP data

    SciTech Connect

    Stone, D.G.

    1984-04-01

    Presently, VSP is being used to predict interval velocity and depth beneath the drill bit. The method is to exploit special properties of the VSP to produce a successful inversion to acoustic impedance. Depth and interval velocity are derived from the acoustic impedance prediction. This technique is often a valuable aid in making drilling decisions. Other rock properties may be computed from the same data. Pore pressure is one such rock parameter that can be computed from interval transit times and depth. The product of interval transit times, depth, normal compaction ratios, and an area constant is pore pressure. Pore pressure prediction is as reliable as the predicted velocities and depths. In reservoir evaluation, and sometimes in the well completion program, porosity is the important rock property. The interval transit times predicted beneath the bit can be used to compute porosity. Unlike pore pressure, porosity computations require knowledge or assumptions about the rock matrix and shale percentages. For certain conditions these values are known. Further penetration of a reef in search of deeper porous zones is an example of a viable condition for porosity prediction. For both these rock properties the same conventions employed by well log analysis in modifying and interpreting results are needed. Where the parameters assumed fit the actual conditions, the results should have merit. If not, further interpretation is required.

  18. Tunable porosity of 3D-networks with germanium nodes.

    PubMed

    Monnereau, Laure; Muller, Thierry; Lang, Mathias; Bräse, Stefan

    2016-01-11

    Eight hyper cross-linked polymers based on tetrakis(4-ethynylphenyl)germanium and tetrakis(4-ethynylphenyl)methane are presented. After investigation of their N2 adsorption properties at 77 K, the porosity of the germanium-based porous organic polymers (POPs) was modulated under acidic conditions, offering an easy and direct way, in a single step, to tune the adsorption properties.

  19. [Aortobifemoral prostheses with "0" porosity. Results after 2 years' experience].

    PubMed

    Escudero, J R; Llagostera, S; Riambau, V; Latorre, E; Upegui, L; Pastor, O; Viver, E

    1990-01-01

    During the last years diverse types of Dacron prosthesis without porosity (because to be impregnated by different materials) have appeared. In the presented study, outcomes from three different types of prosthesis (differentiated by the impregnated material) were evaluated and a comparison with classical prosthesis was made.

  20. Laboratory photometry of regolith analogues: Effect of porosity

    NASA Astrophysics Data System (ADS)

    Kar, A.; Sen, A. K.; Gupta, R.

    2016-10-01

    New Laboratory phase curves are presented, to examine the effect of porosity on reflectance as a function of phase angle for grain size having dimension about half, twice and those larger than the illuminating wavelength. The experimental setup used for generating reflectance data is a goniometric device developed at the Department of Physics, Assam University, Silchar, India. Some of the well-documented samples having different sizes were chosen; alumina, olivine, basalt, rutile, chromite and iron. The sample surfaces were prepared with different porosities, in order to simulate natural regolith surface as much as possible. The wavelength of observation is 632.8 nm. A model based on the Radiative Transfer Equation is presented here to analyze and model the laboratory data. In the present modelling work, the empirical relation of Hapke, Mie theory and Henyey-Greenstein phase function are used. For particles having dimension about half, twice to the wavelength, Mie theory is used to calculate single scattering albedo. Although the Mie theory is insufficient for describing the scattering properties of particles larger than the wavelength, for such large particle single scattering albedo (SSA) is estimated through method of best fit. It has been found that, the porosity has a distinguishable effect on reflectance. Also the contribution of multiple scattering function for different porosity is examined. Further the results presented in the current work, demonstrates the light scattering properties of a diverse collections of regolith like samples.

  1. Scale dependence of intragranular porosity, tortuosity, and tortuosity

    SciTech Connect

    Ewing, Robert G.; Hu, Qinhong; Liu, Chongxuan

    2010-06-17

    Diffusive exchange of solutes between intragranular pores and flowing water is a recognized but poorly understood contributor to dispersion. Intragranular porosity may also contribute to the slow sorption phenomenon. Intragranular pores may be sparsely interconnected, raising the possibility that accessible porosity and diffusive exchange are limited by pore connectivity. We used a pore-scale network model to examine pore connectivity effects on accessible porosity, diffusivity, and tortuosity in spherical particles. The diffusive process simulated was release of a non-sorbing solute initially at equilibrium with the surrounding solution. High-connectivity results were essentially identical to Crank’s analytical solution. Low-connectivity results were consistent with observations reported in the literature, with solute released more quickly at early times than indicated by the analytical solution, and more slowly at late times. Values of accessible porosity, diffusivity, and tortuosity scaled with connection probability, distance to the sphere’s exterior, and/or the sphere’s radius, as predicted by percolation theory. The scaling relationships should be useful in conventional modeling of diffusive processes in porous spherical particles.

  2. Permeability porosity relationships (K, Phi cut-off)

    SciTech Connect

    Djettou, F.; Reda, H.

    1995-08-01

    Several reservoirs of Lower Devonian in Ghadames basin present porosities greater than 10 Pu, but during the test they are rather impermeable. It seems that this phenomena extends to BERKINE and Rhourd Messaoud areas. This seriously affect the estimation of recovery reserves. The best we can do is to study and try to understand reservoir problems. The method we choose is based on statistical analysis of test results and their comparison with core and log measurements. It concerns mainly cummulative curves of productive and non-productive tests (dry test). This involves about 20 wells where are can define: Siegenian with: Fine grained in BBK and ROM Coarse grained toward BRN - Emsian is rather homogeneous in the region. The sand cut-off porosity is greater than 11 Pu. However the reservoir can`t produce itself then we can not take account in reserve estimation. In conclusion, a sandy reservoir of Lower Devonian in Ghadames basin may be very porous (11-12%) and impermeable while in the other cases reservoirs can produce with porosity of 7 or 8 Po. However a HC definition based on cut-off porosity in Ghadames basin should be done before net pay an recovery reserves estimation.

  3. Gas-Filled Capillary Model

    NASA Astrophysics Data System (ADS)

    Steinhauer, L. C.; Kimura, W. D.

    2006-11-01

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration — Laser Wakefield (STELLA-LW) experiment.

  4. QENS investigation of filled rubbers

    NASA Astrophysics Data System (ADS)

    Triolo, A.; Lo Celso, F.; Negroni, F.; Arrighi, V.; Qian, H.; Lechner, R. E.; Desmedt, A.; Pieper, J.; Frick, B.; Triolo, R.

    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface.

  5. The Effect of Volumetric Porosity on Roughness Element Drag

    NASA Astrophysics Data System (ADS)

    Gillies, John; Nickling, William; Nikolich, George; Etyemezian, Vicken

    2016-04-01

    Much attention has been given to understanding how the porosity of two dimensional structures affects the drag force exerted by boundary-layer flow on these flow obstructions. Porous structures such as wind breaks and fences are typically used to control the sedimentation of sand and snow particles or create micro-habitats in their lee. Vegetation in drylands also exerts control on sediment transport by wind due to aerodynamic effects and interaction with particles in transport. Recent research has also demonstrated that large spatial arrays of solid three dimensional roughness elements can be used to reduce sand transport to specified targets for control of wind erosion through the effect of drag partitioning and interaction of the moving sand with the large (>0.3 m high) roughness elements, but porous elements may improve the effectiveness of this approach. A thorough understanding of the role porosity plays in affecting the drag force on three-dimensional forms is lacking. To provide basic understanding of the relationship between the porosity of roughness elements and the force of drag exerted on them by fluid flow, we undertook a wind tunnel study that systematically altered the porosity of roughness elements of defined geometry (cubes, rectangular cylinders, and round cylinders) and measured the associated change in the drag force on the elements under similar Reynolds number conditions. The elements tested were of four basic forms: 1) same sized cubes with tubes of known diameter milled through them creating three volumetric porosity values and increasing connectivity between the tubes, 2) cubes and rectangular cylinders constructed of brass screen that nested within each other, and 3) round cylinders constructed of brass screen that nested within each other. The two-dimensional porosity, defined as the ratio of total surface area of the empty space to the solid surface area of the side of the element presented to the fluid flow was conserved at 0.519 for

  6. A Novel Porosity Model for Use in Hydrocode Simulations

    NASA Technical Reports Server (NTRS)

    Wuennemann, K.; Collins, G. S.; Melosh, H. J.

    2005-01-01

    Introduction: Numerical modeling of impact cratering has reached a high degree of sophistication; however, the treatment of porous materials still poses a large problem in hydrocode calculations. Porosity plays only a minor role in the formation of large craters on most planetary objects, but impacts on comets are believed to be highly affected by the presence of porosity, which may be as much as 80%. The upcoming Deep Impact Mission (launched January 2005) will provide more detailed data about the composition of a comet (Tempel 1) by shooting a approx.370 kg projectile onto the surface of its nucleus. The numerical simulations of such impact events requires an appropriate model for how pore space in the comet is crushed out during the violent initial stage of the impact event. Most hydro-codes compute the pressure explicitly using an "equation of state" (EOS) for each material, which relates changes in density and internal energy to changes in pressure. The added complication introduced by porosity is that changes in a material s density are due to both the closing of pore space (compaction) and compression of the matrix. The amount of resistance to volume change and the amount of irreversible work done during these two processes is very different; it is far easier to compact a porous material sample than to compress a non-porous sample of the same material. As an alternative to existing porosity models, like the Pdot(alpha) model [1], we present a novel approach for dealing with the compaction of porosity in hydrocode calculations.

  7. Can-Filled Crash Barrier

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1983-01-01

    Crash barrier composed largely of used aluminum beverage cans protects occupants of cars in collisions with poles or trees. Lightweight, can-filled barrier very effective in softening impact of an automobile in head-on and off-angle collisions. Preliminary results indicate barrier is effective in collisions up to 40 mi/h (64 km/h).

  8. Filling in the retinal image

    NASA Technical Reports Server (NTRS)

    Larimer, James; Piantanida, Thomas

    1990-01-01

    The optics of the eye form an image on a surface at the back of the eyeball called the retina. The retina contains the photoreceptors that sample the image and convert it into a neural signal. The spacing of the photoreceptors in the retina is not uniform and varies with retinal locus. The central retinal field, called the macula, is densely packed with photoreceptors. The packing density falls off rapidly as a function of retinal eccentricity with respect to the macular region and there are regions in which there are no photoreceptors at all. The retinal regions without photoreceptors are called blind spots or scotomas. The neural transformations which convert retinal image signals into percepts fills in the gaps and regularizes the inhomogeneities of the retinal photoreceptor sampling mosaic. The filling-in mechamism plays an important role in understanding visual performance. The filling-in mechanism is not well understood. A systematic collaborative research program at the Ames Research Center and SRI in Menlo Park, California, was designed to explore this mechanism. It was shown that the perceived fields which are in fact different from the image on the retina due to filling-in, control some aspects of performance and not others. Researchers have linked these mechanisms to putative mechanisms of color coding and color constancy.

  9. Space-filling polyhedral sorbents

    DOEpatents

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  10. Unsteady Capillary Filling By Electrocapillarity

    NASA Astrophysics Data System (ADS)

    Kang, In Seok; Lee, Jung A.

    2016-11-01

    Unsteady filling of electrolyte solution inside a nanochannel by the electrocapillarity effect is studied. The filling rate is predicted as a function of the bulk concentration of the electrolyte, the surface potential (or surface charge density), and the cross sectional shape of the channel. Since the driving force of the flow is the electrocapillarity, it is first analyzed by using the solution of the Poisson-Boltzmann equation. From the analysis, it is found that the results for many different cross sectional shapes can be unified with good accuracy if the hydraulic radius is adopted as the characteristic length scale of the problem. Especially in the case of constant surface potential, for both limits of κh -> 0 and κh -> ∞ , it can be shown theoretically that the electrocapillarity is independent of the cross sectional shape if the hydraulic radius is the same. In order to analyze the geometric effects more systematically, we consider the regular N-polygons with the same hydraulic radius and the rectangles of different aspect ratios. Washburn's approach is then adopted to predict the filling rate of electrolyte solution inside a nanaochannel. It is found that the average filling velocity decreases as N increases in the case of regular N-polygons with the same hydraulic radius. This is because of that the regular N-polygons of the same hydraulic radius share the same inscribing circle. This work has been supported by BK21+ program.

  11. Correlation between porosity and space holder content at different sintering temperatures of aluminum foam

    NASA Astrophysics Data System (ADS)

    Rushdi, N. M. F. M.; Jamaludin, S. B.; Mazlee, M. N.; Jamal, Z. A. Z.

    2016-07-01

    Aluminum foam is the most popular metal foam that can be used as energy absorbers, heat exchangers, air-oil separators and structure core of fuel cells. Melt-foaming agent, melt-gas injection, investment casting and powder-foaming agent techniques can be used to manufacture aluminum foam, but these techniques are too expensive. In this study, the aluminum foam was manufactured via a sintering dissolution process (SDP). Powders of aluminum and sodium chloride as space holder (25, 40, 50 wt. %) were mixed together to produce a homogeneous mixture. The mixture was compacted at 200 MPa followed by sintering at 500, 550 and 600˚C for 2 hours. A warm running water stream was used to dissolve the space holder that was embedded in the aluminum. The result showed that, the space holder content performed a significant role to control the total porosity to a value between 18 and 40%, and the porosity increased with increasing content of space holder and sintering temperature.

  12. Constitutive parameter de-embedding using inhomogeneously-filled rectangular waveguides with longitudinal section modes

    NASA Technical Reports Server (NTRS)

    Park, A.; Dominek, A. K.

    1990-01-01

    Constitutive parameter extraction from S parameter data using a rectangular waveguide whose cross section is partially filled with a material sample as opposed to being completely filled was examined. One reason for studying a partially filled geometry is to analyze the effect of air gaps between the sample and fixture for the extraction of constitutive parameters. Air gaps can occur in high temperature parameter measurements when the sample was prepared at room temperature. Single port and two port measurement approaches to parameter extraction are also discussed.

  13. Effect of heat-treatment temperatures on density and porosity in MgB 2 superconductor

    NASA Astrophysics Data System (ADS)

    Liu, C. F.; Yan, G.; Du, S. J.; Xi, W.; Feng, Y.; Zhang, P. X.; Wu, X. Z.; Zhou, L.

    2003-04-01

    The density, porosity, and microstructures of MgB 2 samples are very important factors for transition critical current density. The effect of heat-treatment temperatures on density and porosity in MgB 2 superconductors has been investigated. The open porosity increases with increasing heat-treatment temperatures, but close porosity decreases. The calculated theory densities from the lattice parameters of the measured samples are 2.6-2.63 g/cm 3. The average measured total porosity (including open and close porosity) is about 50%.

  14. Physicochemical properties and surfaces morphologies evaluation of MTA FillApex and AH plus.

    PubMed

    Borges, Álvaro Henrique; Orçati Dorileo, Maura Cristiane Gonçales; Dalla Villa, Ricardo; Borba, Alexandre Meireles; Semenoff, Tereza Aparecida Delle Vedove; Guedes, Orlando Aguirre; Estrela, Cyntia Rodrigues Araújo; Bandeca, Matheus Coelho

    2014-01-01

    The solubility, pH, electrical conductivity, and radiopacity of AH Plus and MTA FillApex were evaluated. In addition, the surfaces morphologies of the sealers were analyzed by using scanning electron microscopy. For pH test, the samples were immersed in distilled water at different periods of time. The same solution was used for electrical conductivity measurement. The solubility and radiopacity were evaluated according to ANSI/ADA. Statistical analyses were carried out at 5% level of significance. MTA FillApex presented higher mean value for solubility and electrical conductivity. No significant difference was observed in the mean values for pH reading. AH Plus presented higher radiopacity mean values. MTA FillApex presented an external surface with porosities and a wide range of sizes. In conclusion, the materials fulfill the ANSI/ADA requirements when considering the radiopacity and solubility. AH Plus revealed a compact and homogeneous surface with more regular aspects and equal particle sizes.

  15. Numerical Study to Examine the Effect of Porosity on In-Flight Particle Dynamics

    NASA Astrophysics Data System (ADS)

    Kamnis, S.; Gu, S.; Vardavoulias, M.

    2011-03-01

    High velocity oxygen fuel (HVOF) thermal spray has been widely used to deposit hard composite materials such as WC-Co powders for wear-resistant applications. Powder morphology varies according to production methods while new powder manufacturing techniques produce porous powders containing air voids which are not interconnected. The porous microstructure within the powder will influence in-flight thermal and aerodynamic behavior of particles which is expected to be different from fully solid powder. This article is devoted to study the heat and momentum transfer in a HVOF sprayed WC-Co particles with different sizes and porosity levels. The results highlight the importance of thermal gradients inside the particles as a result of microporosity and how HVOF operating parameters need to be modified considering such temperature gradient.

  16. Reversibly switching the surface porosity of a DNA tetrahedron.

    PubMed

    Zhang, Chuan; Tian, Cheng; Li, Xiang; Qian, Hang; Hao, Chenhui; Jiang, Wen; Mao, Chengde

    2012-07-25

    The ability to reversibly switch the surface porosity of nanocages would allow controllable matter transport in and out of the nanocages. This would be a desirable property for many technological applications, such as drug delivery. To achieve such capability, however, is challenging. Herein we report a strategy for reversibly changing the surface porosity of a self-assembled DNA nanocage (a DNA tetrahedron) that is based on DNA hydridization and strand displacement. The involved DNA nanostructures were thoroughly characterized by multiple techniques, including polyacrylamide gel electrophoresis, dynamic light scattering, atomic force microscopy, and cryogenic electron microscopy. This work may lead to the design and construction of stimuli-responsive nanocages that might find applications as smart materials.

  17. Porosity Measurement in Laminated Composites by Thermography and FEA

    NASA Technical Reports Server (NTRS)

    Chu, Tsuchin Philip; Russell, Samuel S.; Walker, James L.; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    This paper presents the correlation between the through-thickness thermal diffusivity and the porosity of composites. Finite element analysis (FEA) was used to determine the transient thermal response of composites that were subjected to laser heating. A series of finite element models were built and thermal responses for isotropic and orthographic materials with various thermal diffusivities subjected to different heating conditions were investigated. Experiments were conducted to verify the models and to estimate the unknown parameters such as the amount of heat flux. The analysis and experimental results show good correlation between thermal diffusivity and porosity in the composite materials. They also show that both laser and flash heating can be used effectively to obtain thermal diffusivity. The current infrared thermography system is developed for use with flash heating. The laser heating models and the FEA results can provide useful tools to develop practical thermal diffusivity measurement scheme using laser heat.

  18. Carbon composition with hierarchical porosity, and methods of preparation

    SciTech Connect

    Mayes, Richard T; Dai, Sheng

    2014-10-21

    A method for fabricating a porous carbon material possessing a hierarchical porosity, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic component, (iii) a dione component in which carbonyl groups are adjacent, and (iv) an acidic component, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a carbon material possessing a hierarchical porosity comprised of mesopores and macropores. Also described are the resulting hierarchical porous carbon material, a capacitive deionization device in which the porous carbon material is incorporated, as well as methods for desalinating water by use of said capacitive deionization device.

  19. Metals Ions Removal by Polymer Membranes of Different Porosity

    PubMed Central

    2013-01-01

    The effect of the amount of pore generating agent (polyvinylpyrrolidone) added to standard polymer membranes containing 18 wt.% of polyethersulfone on the physicochemical properties of the membranes and their capacity for removal of iron and copper ions from the liquid phase was studied. The membranes were obtained by the phase inversion method. The results have shown that the modification of polymer membranes by the use of different amounts of the pore forming agent in their syntheses leads to significant changes in porosity and has beneficial effect on equilibrium water content. The membranes studied were found to show different acid-base surface character, but for all membranes studied, a significant dominance of oxygen groups of acidic character was evidenced. The most effective were the membranes of the lowest content of polyvinylpyrrolidone, while the lowest values of resistance showed the membranes of the highest content of PVP, and so the ones of the greatest porosity. PMID:23818836

  20. Dehydration-induced porosity waves and episodic tremor and slip

    NASA Astrophysics Data System (ADS)

    Skarbek, Rob M.; Rempel, Alan W.

    2016-02-01

    Episodic tremor and slip (ETS) along the subduction interface takes place where there is abundant evidence for elevated, near-lithostatic pore pressures, at sufficiently great depths (30-45 km) that chemical dehydration reactions must act as their dominant source. We simulate fluid and heat flow while tracking the location of a vertically oriented, one-dimensional column of material as it subducts through the slow slip and tremor zone. The material in the column is transformed through a pressure-dependent and temperature-dependent dehydration reaction that we describe with a generalized nonlinear kinetic rate law. Column deformation is largely dominated by viscous creep, with a closure rate that depends linearly on porosity. This behavior causes the dehydration reaction to generate traveling porosity waves that transport increased fluid pressures within the slow slip region. To explore the possibility that the observed periodicity of slow slip and tremor in subduction zones can be explained by the migration of such porosity waves, we derive a dispersion relation that accurately describes our numerical results. We also obtain an expression for how the thickness of the dehydrating layer is expected to vary as a function of the parameters in the reaction rate law. Although the amplitudes of pore pressure perturbations rival those that are produced by known external forcings (e.g., tides or passing surface waves), our analysis suggests that given reasonable estimates of rock viscosity, permeabilities in the range 6.5×10-15 to 5×10-10 m2 are required for porosity wave trains to form at periods comparable to those of slow slip and tremor.

  1. Particle-filled microporous materials

    DOEpatents

    McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.

    1992-07-14

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

  2. Particle-filled microporous materials

    DOEpatents

    McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.; Dyrud, James F.

    1990-01-01

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

  3. Particle-filled microporous materials

    DOEpatents

    McAllister, J.W.; Kinzer, K.E.; Mrozinski, J.S.; Johnson, E.J.; Dyrud, J.F.

    1990-09-18

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated. 3 figs.

  4. Safety in Royal Filling Factories

    DTIC Science & Technology

    1950-10-01

    factories and certain special trials were staged to ascertain effect of explosion on underground Magazines. (See C.S.A.R*s report, Glascoed trials). On...spacing were the result of long experience of the effects of explosions in filling, and incidentally resulted in a considerable economy in cost of...etc (9) Any ignition is quenched in its initial stages and/or an explosive effect kept to a minimum. (10) Operatives are made fully aware of the

  5. Effective Thermal Conductivity of High Porosity Open Cell Nickel Foam

    NASA Technical Reports Server (NTRS)

    Sullins, Alan D.; Daryabeigi, Kamran

    2001-01-01

    The effective thermal conductivity of high-porosity open cell nickel foam samples was measured over a wide range of temperatures and pressures using a standard steady-state technique. The samples, measuring 23.8 mm, 18.7 mm, and 13.6 mm in thickness, were constructed with layers of 1.7 mm thick foam with a porosity of 0.968. Tests were conducted with the specimens subjected to temperature differences of 100 to 1000 K across the thickness and at environmental pressures of 10(exp -4) to 750 mm Hg. All test were conducted in a gaseous nitrogen environment. A one-dimensional finite volume numerical model was developed to model combined radiation/conduction heat transfer in the foam. The radiation heat transfer was modeled using the two-flux approximation. Solid and gas conduction were modeled using standard techniques for high porosity media. A parameter estimation technique was used in conjunction with the measured and predicted thermal conductivities at pressures of 10(exp -4) and 750 mm Hg to determine the extinction coefficient, albedo of scattering, and weighting factors for modeling the conduction thermal conductivity. The measured and predicted conductivities over the intermediate pressure values differed by 13%.

  6. Interaction of Porosity with a Planar Solid/Liquid Interface

    NASA Technical Reports Server (NTRS)

    Catalina, Adrian V.; Stefanescu, Doru M.; Sen, Subhayu; Kaukler, William K.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    In this paper, an investigation of the interaction between gas porosity and a planar solid/liquid (SL) interface is reported. A two-dimensional numerical model able to accurately track sharp SL interfaces during solidification of pure metals and alloys is proposed. The finite difference method and a rectangular undeformed grid are used for computation. The SL interface is described through the points of intersection with the grid lines. Its motion is determined by the thermal and solute gradients at each particular point. Changes of the interface temperature because of capillarity or solute redistribution as well as any perturbation of the thermal and solute field produced by the presence of non-metallic inclusions can be computed. To validate the model, the dynamics of the interaction between a gas pore and a solidification front in metal alloys was observed using a state of the art X-ray Transmission Microscope. The experiments included observation of the distortion of the SL interface near a pore, real-time measurements of the growth rate and the change in shape of the porosity during interaction with an advancing SL interface in pure Al and Al-0.25 wt% Au alloy. In addition, porosity induced solute segregation patterns surrounding a pore were also quantified.

  7. Computer Based Porosity Design by Multi Phase Topology Optimization

    NASA Astrophysics Data System (ADS)

    Burblies, Andreas; Busse, Matthias

    2008-02-01

    A numerical simulation technique called Multi Phase Topology Optimization (MPTO) based on finite element method has been developed and refined by Fraunhofer IFAM during the last five years. MPTO is able to determine the optimum distribution of two or more different materials in components under thermal and mechanical loads. The objective of optimization is to minimize the component's elastic energy. Conventional topology optimization methods which simulate adaptive bone mineralization have got the disadvantage that there is a continuous change of mass by growth processes. MPTO keeps all initial material concentrations and uses methods adapted from molecular dynamics to find energy minimum. Applying MPTO to mechanically loaded components with a high number of different material densities, the optimization results show graded and sometimes anisotropic porosity distributions which are very similar to natural bone structures. Now it is possible to design the macro- and microstructure of a mechanical component in one step. Computer based porosity design structures can be manufactured by new Rapid Prototyping technologies. Fraunhofer IFAM has applied successfully 3D-Printing and Selective Laser Sintering methods in order to produce very stiff light weight components with graded porosities calculated by MPTO.

  8. Core image analysis of matrix porosity in The Geysers reservoir

    SciTech Connect

    Nielson, Dennis L.; Nash, Greg; Hulen, Jeffrey B.; Tripp, Alan C.

    1993-01-28

    Adsorption is potentially an important consideration when calculating reserves at The Geysers. Our investigations of the mineralogical relationships in core samples have shown matrix pore spaces to be largely associated with fractures. Dissolution of calcite from hydrothermal veins increases porosity in the graywacke reservoir. The high relative surface area of secondary alteration phases could promote adsorption. In order to quantify porosity distribution and surface area, Scanning Electron Microscope (SEM) images were analyzed using software developed for the interpretation of satellite imagery, This software classifies the images as either crystal or pore and then accumulates data on pore size, total porosity and surface area of the mineral-pore interface. Review of literature shows that data on thickness of adsorbed water layer does not exist for many of the mineral phases of interest in The Geysers. We have assumed thicknesses of 10, 100, and 5300 Angstroms for the adsorbed layer and calculated the relative proportions of adsorbed water. These calculations show 0.005%, 0.05%, and 2.5% of total water would be adsorbed using the above thicknesses.

  9. Revisiting the statistical analysis of pyroclast density and porosity data

    NASA Astrophysics Data System (ADS)

    Bernard, B.; Kueppers, U.; Ortiz, H.

    2015-07-01

    Explosive volcanic eruptions are commonly characterized based on a thorough analysis of the generated deposits. Amongst other characteristics in physical volcanology, density and porosity of juvenile clasts are some of the most frequently used to constrain eruptive dynamics. In this study, we evaluate the sensitivity of density and porosity data to statistical methods and introduce a weighting parameter to correct issues raised by the use of frequency analysis. Results of textural investigation can be biased by clast selection. Using statistical tools as presented here, the meaningfulness of a conclusion can be checked for any data set easily. This is necessary to define whether or not a sample has met the requirements for statistical relevance, i.e. whether a data set is large enough to allow for reproducible results. Graphical statistics are used to describe density and porosity distributions, similar to those used for grain-size analysis. This approach helps with the interpretation of volcanic deposits. To illustrate this methodology, we chose two large data sets: (1) directed blast deposits of the 3640-3510 BC eruption of Chachimbiro volcano (Ecuador) and (2) block-and-ash-flow deposits of the 1990-1995 eruption of Unzen volcano (Japan). We propose the incorporation of this analysis into future investigations to check the objectivity of results achieved by different working groups and guarantee the meaningfulness of the interpretation.

  10. Revisiting the statistical analysis of pyroclast density and porosity data

    NASA Astrophysics Data System (ADS)

    Bernard, B.; Kueppers, U.; Ortiz, H.

    2015-03-01

    Explosive volcanic eruptions are commonly characterized based on a thorough analysis of the generated deposits. Amongst other characteristics in physical volcanology, density and porosity of juvenile clasts are some of the most frequently used characteristics to constrain eruptive dynamics. In this study, we evaluate the sensitivity of density and porosity data and introduce a weighting parameter to correct issues raised by the use of frequency analysis. Results of textural investigation can be biased by clast selection. Using statistical tools as presented here, the meaningfulness of a conclusion can be checked for any dataset easily. This is necessary to define whether or not a sample has met the requirements for statistical relevance, i.e. whether a dataset is large enough to allow for reproducible results. Graphical statistics are used to describe density and porosity distributions, similar to those used for grain-size analysis. This approach helps with the interpretation of volcanic deposits. To illustrate this methodology we chose two large datasets: (1) directed blast deposits of the 3640-3510 BC eruption of Chachimbiro volcano (Ecuador) and (2) block-and-ash-flow deposits of the 1990-1995 eruption of Unzen volcano (Japan). We propose add the use of this analysis for future investigations to check the objectivity of results achieved by different working groups and guarantee the meaningfulness of the interpretation.

  11. Compost addition reduces porosity and chlordecone transfer in soil microstructure.

    PubMed

    Woignier, Thierry; Clostre, Florence; Fernandes, Paula; Rangon, Luc; Soler, Alain; Lesueur-Jannoyer, Magalie

    2016-01-01

    Chlordecone, an organochlorine insecticide, pollutes soils and contaminates crops and water resources and is biomagnified by food chains. As chlordecone is partly trapped in the soil, one possible alternative to decontamination may be to increase its containment in the soil, thereby reducing its diffusion into the environment. Containing the pesticide in the soil could be achieved by adding compost because the pollutant has an affinity for organic matter. We hypothesized that adding compost would also change soil porosity, as well as transport and containment of the pesticide. We measured the pore features and studied the nanoscale structure to assess the effect of adding compost on soil microstructure. We simulated changes in the transport properties (hydraulic conductivity and diffusion) associated with changes in porosity. During compost incubation, the clay microstructure collapsed due to capillary stresses. Simulated data showed that the hydraulic conductivity and diffusion coefficient were reduced by 95 and 70% in the clay microstructure, respectively. Reduced transport properties affected pesticide mobility and thus helped reduce its transfer from the soil to water and to the crop. We propose that the containment effect is due not only to the high affinity of chlordecone for soil organic matter but also to a trapping mechanism in the soil porosity.

  12. Emulsion Inks for 3D Printing of High Porosity Materials.

    PubMed

    Sears, Nicholas A; Dhavalikar, Prachi S; Cosgriff-Hernandez, Elizabeth M

    2016-08-01

    Photocurable emulsion inks for use with solid freeform fabrication (SFF) to generate constructs with hierarchical porosity are presented. A high internal phase emulsion (HIPE) templating technique was utilized to prepare water-in-oil emulsions from a hydrophobic photopolymer, surfactant, and water. These HIPEs displayed strong shear thinning behavior that permitted layer-by-layer deposition into complex shapes and adequately high viscosity at low shear for shape retention after extrusion. Each layer was actively polymerized with an ultraviolet cure-on-dispense (CoD) technique and compositions with sufficient viscosity were able to produce tall, complex scaffolds with an internal lattice structure and microscale porosity. Evaluation of the rheological and cure properties indicated that the viscosity and cure rate both played an important role in print fidelity. These 3D printed polyHIPE constructs benefit from the tunable pore structure of emulsion templated material and the designed architecture of 3D printing. As such, these emulsion inks can be used to create ultra high porosity constructs with complex geometries and internal lattice structures not possible with traditional manufacturing techniques.

  13. Interaction of Porosity with a Planar Solid/Liquid Interface

    NASA Technical Reports Server (NTRS)

    Catalina, Adrian V.; Stefanescu, Doru M.; Sen, Subhayu; Kaukler, William F.

    2004-01-01

    In this article, an investigation of the interaction between gas porosity and a planar solid/liquid (SL) interface is reported. A two-dimensional numerical model able to accurately track sharp SL interfaces during solidification of pure metals and alloys is proposed. The finite-difference method and a rectangular undeformed grid are used for computation. The SL interface is described through the points of intersection with the grid lines. Its motion is determined by the thermal and solute gradients at each particular point. Changes of the interface temperature because of capillarity or solute redistribution as well as any perturbation of the thermal and solute field produced by the presence of non-metallic inclusions can be computed. To validate the model, the dynamics of the interaction between a gas pore and a solidification front in metal alloys was observed using a state of the art X-ray transmission microscope (XTM). The experiments included observation of the distortion of the SL interface near a pore, real-time measurements of the growth rate, and the change in shape of the porosity during interaction with the SL interface in pure Al and Al-0.25 wt pct Au alloy. In addition, porosity-induced solute segregation patterns surrounding a pore were also quantified.

  14. Reduction of Wake-Stator Interaction Noise Using Passive Porosity

    NASA Technical Reports Server (NTRS)

    Tinetti, Ana F.; Kelly, Jeffrey J.; Thomas, Russell H.; Bauer, Steven X. S.

    2002-01-01

    The present study was conducted to assess the potential of Passive Porosity Technology as a mechanism to reduce interaction noise in turbomachinery by reducing the fluctuating forces acting on the vane surfaces. To do so, a typical fan stator airfoil was subjected to the effects of a transversely moving wake; time histories of the primitive aerodynamic variables, obtained from Computational Fluid Dynamics (CFD) solutions, were then input into an acoustic prediction code. This procedure was performed on the solid airfoil to obtain a baseline, and on a series of porous configurations in order to isolate those that yield maximum noise reductions without compromising the aerodynamic performance of the stator. It was found that communication between regions of high pressure differential - made possible by the use of passive porosity - is necessary to significantly alter the noise radiation pattern of the stator airfoil. In general, noise reductions were obtained for those configurations incorporating passive porosity in the region between x/c is approximately 0.15 on the suction side of the airfoil and x/c is approximately 0.20 on the pressure side. Reductions in overall radiated noise of approximately 1.0 dB were obtained. The noise benefit increased to about 2.5 dB when the effects of loading noise alone were considered.

  15. 24. BUILDING NO. 452, ORDNANCE FACILITY (BAG CHARGE FILLING PLANT), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. BUILDING NO. 452, ORDNANCE FACILITY (BAG CHARGE FILLING PLANT), INTERIOR VIEW LOOKING WEST AT NORTH END OF CENTRAL CORRIDOR (ROOM 3). STAIRWAY WORKBENCH WITH COMPRESSED-AIR POWERED CARTRIDGE LOADER. ARMORED PASS-THROUGH OF TRANSFER BOX FOR PASSING EXPLOSIVES MATERIALS THROUGH TO NEXT ROOM TO THE NORTH. - Picatinny Arsenal, 400 Area, Gun Bag Loading District, State Route 15 near I-80, Dover, Morris County, NJ

  16. Geochemical and Mineralogical Evaluation of CO2-Brine-Rock Experiments: Characterizing Porosity and Permeability Variations in the Cambrian Mount Simon Sandstone

    NASA Astrophysics Data System (ADS)

    Gonzalez, A. B.; Bowen, B. B.

    2012-12-01

    in major ion and trace element concentration suggesting that dissolution of soluble phases occurred during the experiment. 174 precisely placed SEM/EDX measurements of overall elemental composition and 144 pores from the interior of the samples (presumably not in contact with the CO2 and brine) and the exterior edges of the samples (in direct contact with the CO2 and brine) show variations in cation concentration and pore-filling textures. In general, the sample interiors have more open pores and the edges have higher cation concentrations and pores filled with secondary minerals. Current results indicate carbon dioxide injection into samples from the same formation but dissimilar textural and mineral compositions can have variable affects on overall permeability and porosity.

  17. Porosity of temporary denture soft liners containing antifungal agents

    PubMed Central

    Lima, Jozely Francisca Mello; Maciel, Janaína Gomes; Hotta, Juliana; Vizoto, Ana Carolina Pero; Honório, Heitor Marques; Urban, Vanessa Migliorini; Neppelenbroek, Karin Hermana

    2016-01-01

    ABSTRACT Incorporation of antifungals in temporary denture soft liners has been recommended for denture stomatitis treatment; however, it may affect their properties. Objective: To evaluate the porosity of a tissue conditioner (Softone) and a temporary resilient liner (Trusoft) modified by minimum inhibitory concentrations (MICs) of antifungal agents for Candida albicans biofilm. Material and Methods: The porosity was measured by water absorption, based on exclusion of the plasticizer effect. Initially, it was determined by sorption isotherms that the adequate storage solution for specimens (65×10×3.3 mm) of both materials was 50% anhydrous calcium chloride (S50). Then, the porosity factor (PF) was calculated for the study groups (n=10) formed by specimens without (control) or with drug incorporation at MICs (nystatin: Ny-0.032 g, chlorhexidine diacetate: Chx-0.064 g, or ketoconazole: Ke-0.128 g each per gram of soft liner powder) after storage in distilled water or S50 for 24 h, seven and 14 d. Data were statistically analyzed by 4-way repeated measures ANOVA and Tukey's test (α=.05). Results: Ke resulted in no significant changes in PF for both liners in water over 14 days (p>0.05). Compared with the controls, Softone and Trusoft PFs were increased at 14-day water immersion only after addition of Ny and Chx, and Chx, respectively (p<0.05). Both materials showed no significant changes in PF in up to 14 days of S50 immersion, compared with the controls (p>0.05). In all experimental conditions, Softone and Trusoft PFs were significantly lower when immersed in S50 compared with distilled water (p<0.05). Conclusions: The addition of antifungals at MICs resulted in no harmful effects for the porosity of both temporary soft liners in different periods of water immersion, except for Chx and Ny in Softone and Chx in Trusoft at 14 days. No deleterious effect was observed for the porosity of both soft liners modified by the drugs at MICs over 14 days of S50 immersion

  18. Effects of porosity distribution and porosity volume fraction on the electromechanical properties of 3-3 piezoelectric foams

    NASA Astrophysics Data System (ADS)

    Nguyen, B. V.; Challagulla, K. S.; Venkatesh, T. A.; Hadjiloizi, D. A.; Georgiades, A. V.

    2016-12-01

    Unit-cell based finite element models are developed to completely characterize the role of porosity distribution and porosity volume fraction in determining the elastic, dielectric and piezoelectric properties as well as relevant figures of merit of 3-3 type piezoelectric foam structures. Eight classes of foam structures which represent structures with different types and degrees of uniformity of porosity distribution are identified; a Base structure (Class I), two H-type foam structures (Classes II, and III), a Cross-type foam structure (Class IV) and four Line-type foam structures (Classes V, VI, VII, and VIII). Three geometric factors that influence the electromechanical properties are identified: (i) the number of pores per face, pore size and the distance between the pores; (ii) pore orientation with respect to poling direction; (iii) the overall symmetry of the pore distribution with respect to the center of the face of the unit cell. To assess the suitability of these structures for such applications as hydrophones, bone implants, medical imaging and diagnostic devices, five figures of merit are determined via the developed finite element model; the piezoelectric coupling constant (K t ), the acoustic impedance (Z), the piezoelectric charge coefficient (d h ), the hydrostatic voltage coefficient (g h ), and the hydrostatic figure of merit (d h g h ). At high material volume fractions, foams with non-uniform Line-type porosity (Classes V and VII) where the pores are preferentially distributed perpendicular to poling direction, are found to exhibit the best combination of desirable piezoelectric figures of merit. For example, at about 50% volume fraction, the d h , g h , and d h g h figures of merit are 55%, 1600% and 2500% higher, respectively, for Classes V and VII of Line-like foam structures compared with the Base structure.

  19. Note on the relationship between porosity data and intervessel pit dimension

    SciTech Connect

    Murphey, W.K.; Elder, T.J.; Blankenhorn, P.R.

    1980-01-01

    Data on porosity, charring temperature, mercury intrusion, pit dimensions, and density of black cherry char are summarized and examined statistically in an attempt to elucidate relationships between measured parameters. Pit dimensions were not related to porosity, but were related to real density. Porosity is found to be related to mercury intrusion, real density and temperature. 1 figure, 2 tables.

  20. Fatigue Crack and Porosity Measurement in Composite Materials by Thermographic and Ultrasonic Methods

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Russell, Samuel S.; Suits, Michael W.; Workman, Gary L.

    2003-01-01

    Contents include the following: 1. Purpose. Detect thermo-mechanically induced intra-ply fatigue microcracking and manufactured porosity in unlined composite pressure vessels. 2. Defect descriptions. Porosity, microcracking. 3. Thermography. Overview of technique. Strengths and Weaknesses. Examples of its use for porosity detection. 4. Resonant ultrasound spectroscopy. Overview of technique. Strengths and Weaknesses. Examples of its use for microcracking detection. Conclusions.

  1. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    NASA Astrophysics Data System (ADS)

    Patel, Binay S.

    and modeled fracture energy results. Furthermore, the contribution of microcracking was most prevalent at lower filler contents which suggests that the presence of microcracking may account for the previously unexplained improvements in fracture behavior attained in silica-filled epoxy nanocomposites at low filler contents. Secondly, surface modification through the application of three different propriety surface treatments ("A", "B" and "C") was found to greatly influence the processibility and fracture behavior of silica-filled epoxy nanocomposites. B-treated silica nanoparticles were found to readily form micron-scale agglomerates, settled during nanocomposite curing and showed no improvement in fracture toughness with increasing filler content. In contrast, the nanocomposites consisting of A-treated and C-treated silica nanoparticles yielded morphologies primarily containing well-dispersed nanoparticles. Therefore, fracture toughness improved with increasing filler content. Finally, particle porosity was found to have no significant effect on fracture behavior for the range of silica-filled epoxy nanocomposites investigated. Lower density porous silica nanoparticles were just as effective toughening agents as higher density non-porous silica nanoparticles. Consequently, the potential exists for the use of toughened-epoxies in lightweight structural applications.

  2. [Scanning electron microscopic study of so-called carvable composite filling materials after over one-year functional period].

    PubMed

    Triadan, H

    1979-03-01

    28 class-5 and 16 class-1 fillings were made from the composite material "Epoxydent" on a macaca speciosa monkey and examined with the electron microscope after a 15 months functional period. Statistically significant differences in the size of the marginal space were found to be larger than in comparable composites Adaptic, Concise, Compo-Cap and Cosmic. The spaces were frequently not located on the filling margin but inside, within the filling material. This is attributed to the "carving" technique during the gel phase of setting. The surface shows abrasions and porosities with loss of particles, sometimes fractures and discolored margins with secondary caries. It is not recommended to replace metal fillings by so-called carvable composits.

  3. Influence of activated carbon porosity and surface oxygen functionalities' presence on adsorption of acetonitrile as a simple polar volatile organic compound.

    PubMed

    Furmaniak, Sylwester

    2015-01-01

    Based on series of porous carbon models, systematic Monte Carlo studies on the adsorption of acetonitrile (as a simple representative of polar volatile organic compounds) were performed. The influence of porosity and chemical composition of the carbon surface on CH3CN adsorption was studied and it was shown that both the factors influenced the adsorption mechanism. A decrease in the pore size and the introduction of oxygen surface groups led to a rise in adsorption energy and to an increase in the filling of accessible volume in the low-pressure part of the isotherm. However, from a practical point of view, it is easier to increase the adsorption by introducing polar groups on the carbon surface than by modifying the porosity.

  4. Comparative in vitro investigation of different methods for temporary root canal filling with aqueous suspensions of calcium hydroxide.

    PubMed

    Staehle, H J; Thomä, C; Müller, H P

    1997-06-01

    Three methods for temporarily filling root canals with calcium hydroxide pastes were compared. Each of 20 root canals of extracted, human, single-rooted teeth was shaped with hand instruments under standardized conditions up to ISO size 50 and filled using a syringe system, a lentulo spiral or an endodontic reamer. Quality of fillings was assessed radiographically and by inspecting ground preparations. Ridit (relative to an identified distribution) analysis was employed to confirm differences in frequencies of certain quality criteria obtained with various application methods. With regard to degree of obturation and occurrence of porosities, application of temporary fillings with a lentulo spiral or syringe system revealed significantly better results than application with hand instruments (reamer). No differences with regard to degree of obturation were detected when comparing results obtained with syringe or lentulo. Fewer porosities in the apical part of the root canal were seen, both on radiographs and ground sections, with the syringe system compared with the lentulo spiral. In the presence of some contradictory reports found in the literature, the present study suggests that, after straight or slightly curved root canals have been shaped up to at least ISO size 50, high quality temporary root canal fillings may be obtained by application of an aqueous suspension of calcium hydroxide with a syringe system.

  5. Density and porosity as controls on charcoal storage in soils

    NASA Astrophysics Data System (ADS)

    Masiello, C. A.; Liu, Z.; Ziegelgruber, K. L.; Dugan, B.; Gonnermann, H.; Chuang, V. J.; Zygourakis, K.

    2012-04-01

    A number of studies have documented very low biotic and abiotic decomposition rates of charcoal in the environment, leading to the assumption that it stays within soils after deposition. This assumption forms one tenet of a promising carbon sequestration technique, soil biochar amendment. Laboratory and greenhouse trials with biochar (charcoal produced for addition to soil) do show that charcoal remains in soils after amendment. However, when charcoal has been added to soils in field trials, its retention rate in soils is highly variable. Low retention rates have been reported in some environments, leading to questions about its physical movement across landscapes. Density and porosity are fundamental physical characteristics that play a key role in determining charcoal soil residence time. Measuring the density of charcoal has been challenging historically because of its very high porosity (approaching 80%), making standard fluid displacement methods of density measurement error-prone. Here we review techniques available to measure the density and porosity of BC, focusing on two measurements: skeletal density (the density of the solid component of BC), and envelope density (the mass of a BC sample divided by the volume of its exterior envelope). We present skeletal and envelope density data for environmental charcoal samples and for a series of laboratory-produced charcoals, showing that the skeletal density of charcoal is significantly greater than 1.0 g/cc, while the envelope density is significantly less than 1.0 g/cc. This difference means that pore connectivity and pore structure will be important to quantify to understand landscape movement of charcoal.

  6. Filling of carbon nanotubes and nanofibres

    PubMed Central

    Gately, Reece D

    2015-01-01

    Summary The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications. PMID:25821693

  7. 7 CFR 58.923 - Filling containers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filling containers. 58.923 Section 58.923 Agriculture... Procedures § 58.923 Filling containers. (a) The filling of small containers with product shall be done in a sanitary manner. The containers shall not contaminate or detract from the quality of the product in any...

  8. Depositional model, dolomitization, and porosity of Henryhouse Formation (Silurian), Anadarko basin, Oklahoma

    SciTech Connect

    Beardall, G.B.

    1987-08-01

    The Upper Silurian Henryhouse Formation, which is part of the Hunton Group, is a major hydrocarbon reservoir in the Anadarko basin. Three basic lithofacies are present in the Henryhouse, based on sedimentary structures, lithology, fossil content, and fabric relationships. These facies, represented in general by massive lime mudstone with diverse fauna, burrowed dolowackestone/packstone with mainly crinoids, and massive to laminated dolomudstone with fenestral fabrics and sparse fauna, are inferred to represent subtidal, intertidal, and supratidal environments, respectively. These facies comprise a vertical sequence that represents regressive deposition. The Henryhouse consists of several of these sequences. The Henryhouse commonly is partly or completely dolomitized in western Oklahoma. Three stages of dolomitization were documented: (1) penecontemporaneous hypersaline dolomite occurring as brownish, hypidiotopic rhombs concentrated in the supratidal and intertidal facies, (2) mixed marine and freshwater dolomite occurring as white rims around preexisting hypersaline dolomite, and as subhedral, white rhombs in vugs and molds, and (3) deep-burial vug, mold, and fracture-filling saddle dolomite. Production in the Henryhouse is generally from porous zones in dolomite. However, lithofacies reflecting depositional environments in which they were formed are equally important in porosity development.

  9. Thermal and ultrasonic evaluation of porosity in composite laminates

    NASA Technical Reports Server (NTRS)

    Johnston, Patrick H.; Winfree, William P.; Long, Edward R., Jr.; Kullerd, Susan M.; Nathan, N.; Partos, Richard D.

    1992-01-01

    The effects of porosity on damage incurred by low-velocity impact are investigated. Specimens of graphite/epoxy composite were fabricated with various volume fractions of voids. The void fraction was independently determined using optical examination and acid resin digestion methods. Thermal diffusivity and ultrasonic attenuation were measured, and these results were related to the void volume fraction. The relationship between diffusivity and fiber volume fraction was also considered. The slope of the ultrasonic attenuation coefficient was found to increase linearly with void content, and the diffusivity decreased linearly with void volume fraction, after compensation for an approximately linear dependence on the fiber volume fraction.

  10. Process of making porous ceramic materials with controlled porosity

    DOEpatents

    Anderson, Marc A.; Ku, Qunyin

    1993-01-01

    A method of making metal oxide ceramic material is disclosed by which the porosity of the resulting material can be selectively controlled by manipulating the sol used to make the material. The method can be used to make a variety of metal oxide ceramic bodies, including membranes, but also pellets, plugs or other bodies. It has also been found that viscous sol materials can readily be shaped by extrusion into shapes typical of catalytic or adsorbent bodies used in industry, to facilitate the application of such materials for catalytic and adsorbent applications.

  11. Condensation Enhancement by Surface Porosity: Three-Stage Mechanism.

    PubMed

    Yarom, Michal; Marmur, Abraham

    2015-08-18

    Surface defects, such as pores, cracks, and scratches, are naturally occurring and commonly found on solid surfaces. However, the mechanism by which such imperfections promote condensation has not been fully explored. In the current paper we thermodynamically analyze the ability of surface porosity to enhance condensation on a hydrophilic solid. We show that the presence of a surface-embedded pore brings about three distinct stages of condensation. The first is capillary condensation inside the pore until it is full. This provides an ideal hydrophilic surface for continuing the condensation. As a result, spontaneous condensation and wetting can be achieved at lower vapor pressure than on a smooth surface.

  12. Porosity structures in synthetic quartz veins examined by micro X-ray CT

    NASA Astrophysics Data System (ADS)

    Yamada, R.; Okamoto, A.; Saishu, H.; Nakamura, M.; Okumura, S.; Sasaki, O.; Tsuchiya, N.

    2013-12-01

    Ubiquitous occurrences of quartz veins suggest that dissolution/precipitation of silica provides significant effects on the hydrological and mechanical properties within the crust. For example, a model has been proposed that fracture sealing processes control the change of pore fluid pressure and thus earthquake cycle. Previous studies on natural quartz veins have focused on estimates of P-T conditions, stress and strain fields and fluid compositions; however, details of dynamics of fluid flow and how fractures are sealed during vein formation are still unclear. In this study, we synthesized quartz veins by the hydrothermal experiments, and observed the aperture structures by using X-ray CT. The purpose of this study is to clarify how aperture structures evolve during vein formation especially focusing on effect of the state of water (vapor and supercritical region). We conducted the hydrothermal flow-through experiments for quartz precipitation from Si-supersaturated solutions under supercritical (430C, 30MPa) and vapor condition (370C, 20MPa). The experimental apparatus consists of two vessels for preparation of the Si-supersaturated solution and for precipitation, respectively. The precipitation vessel has double-structure: the main flow path was the inner alumina tube (diameter=4mm), and the outer SUS tube was filled with static solutions. Two situations were examined as the inner tubes; one is porous media composed of closed packed alumina balls(1mm in size), and the other one is fracture. The advantage of this system is that we can take out the non-destructive sample for the analyses by X-ray CT. Significant porosity reduction by silica precipitation at porous media. Under supercritical condition, amorphous silica was predominantly formed with covering the surfaces of the alumina balls and alumina tube, and discrete quartz crystal (50μm) within the amorphous silica layers. The porosity (Φ) gradually decreases with minimal porosity (Φ = 0.4) at ˜ 38mm from

  13. Mechanical behaviour of dacite from Mount St. Helens (USA): A link between porosity and lava dome extrusion mechanism (dome or spine)?

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Russell, J. K.; Kennedy, L. A.

    2016-12-01

    than 1980 dome material and remains brittle even at high effective pressures, a consequence of their low preserved porosities. Only the porous (porosity 0.32) 1980 dome material deformed in a ductile manner (i.e., no macroscopic shear fracture) at effective pressures relevant for edifice deformation. Spine formation typically involves the extrusion of low-porosity material along faults that envelop the magma-filled conduit (i.e., brittle deformation), suggesting that the extrusion mechanism (dome or spine) may be a consequence of slow ascent rates and efficient pre-eruptive outgassing. Well-outgassed, low-porosity (slow ascent rate) materials favour a brittle mode of failure promoting spine extrusion, while poorly-outgassed, high-porosity (fast ascent rate) materials result in blocky domes or lobes. A crystal content-porosity map for brittle (spine) versus ductile (blocky dome) behaviour demonstrates that the window for brittle deformation is small and offers an explanation as to why spine and whaleback structures are relatively rare in nature.

  14. Intragranular porosity in Hanford sand grains after reaction with caustic tank wastes: Quantification and implications for reactive transport

    NASA Astrophysics Data System (ADS)

    Crandell, L. E.; Peters, C. A.; Um, W.; Jones, K. W.; Lindquist, W. B.

    2011-12-01

    Reactions of caustic tank waste with sediments in the 200 East Area of the Hanford site cause quartz and primary aluminosilicate minerals to dissolve. Secondary minerals of sodalite and cancrinite have been shown to nucleate on, and cement together, quartz grains. These secondary precipitates have been found to uptake radionuclides in their network of channels and cages. In this work, thin sections from unreacted and reacted column experiments packed with Hanford sand grains were imaged using 2D Scanning Electron Microscopy (SEM). SEM image analysis reveals large amounts of intragranular pore space in both the reacted and unreacted sands. Grayscale Backscattered Electron (BSE) images were thresholded to separate grain and pore pixels. To quantify the amount of intragranular pore space, a set of images were manually created with the intragranular pore space removed, or the grains filled-in. Porosity, and intragranular porosity, was determined by counting and comparing the number of pore pixels in each pair of images. Intragranular pore space accounts for up to 14% of total porosity. Quartz dissolution in intragranular regions increases the proportion of intragranular pore space in reacted samples. Diffusion of tank waste into these free silica rich areas provides a favorable environment for cancrinite precipitates to form and a potential significant trapping mechanism for radionuclides. Part of this work was to quantify where, within a single pore and a network of pores, precipitation occurred. While the bulk amount of cancrinite precipitation occurred on grain surfaces, cancrinite precipitates were also found in intragranular pore spaces. Up to 10% of total precipitation occurred in intragranular pore space. However, as the system recovers and clean water flow returns, radionuclides incorporated into precipitates in intragranular regions may act as a secondary long term leaching source for contaminants. To determine the trapping or leaching potential from

  15. Modeling ozone removal to indoor materials, including the effects of porosity, pore diameter, and thickness.

    PubMed

    Gall, Elliott T; Siegel, Jeffrey A; Corsi, Richard L

    2015-04-07

    We develop an ozone transport and reaction model to determine reaction probabilities and assess the importance of physical properties such as porosity, pore diameter, and material thickness on reactive uptake of ozone to five materials. The one-dimensional model accounts for molecular diffusion from bulk air to the air-material interface, reaction at the interface, and diffusive transport and reaction through material pore volumes. Material-ozone reaction probabilities that account for internal transport and internal pore area, γ(ipa), are determined by a minimization of residuals between predicted and experimentally derived ozone concentrations. Values of γ(ipa) are generally less than effective reaction probabilities (γ(eff)) determined previously, likely because of the inclusion of diffusion into substrates and reaction with internal surface area (rather than the use of the horizontally projected external material areas). Estimates of γ(ipa) average 1 × 10(-7), 2 × 10(-7), 4 × 10(-5), 2 × 10(-5), and 4 × 10(-7) for two types of cellulose paper, pervious pavement, Portland cement concrete, and an activated carbon cloth, respectively. The transport and reaction model developed here accounts for observed differences in ozone removal to varying thicknesses of the cellulose paper, and estimates a near constant γ(ipa) as material thickness increases from 0.02 to 0.16 cm.

  16. Characterization of Porosity Development in Oxidized Graphite using Automated Image Analysis Techniques

    SciTech Connect

    Contescu, Cristian I; Burchell, Timothy D

    2009-09-01

    This document reports on initial activities at ORNL aimed at quantitative characterization of porosity development in oxidized graphite specimens using automated image analysis (AIA) techniques. A series of cylindrical shape specimens were machined from nuclear-grade graphite (type PCEA, from GrafTech International). The specimens were oxidized in air to various levels of weight loss (between 5 and 20 %) and at three oxidation temperatures (between 600 and 750 oC). The procedure used for specimen preparation and oxidation was based on ASTM D-7542-09. Oxidized specimens were sectioned, resin-mounted and polished for optical microscopy examination. Mosaic pictures of rectangular stripes (25 mm x 0.4 mm) along a diameter of sectioned specimens were recorded. A commercial software (ImagePro) was evaluated for automated analysis of images. Because oxidized zones in graphite are less reflective in visible light than the pristine, unoxidized material, the microstructural changes induced by oxidation can easily be identified and analyzed. Oxidation at low temperatures contributes to development of numerous fine pores (< 100 m2) distributed more or less uniformly over a certain depth (5-6 mm) from the surface of graphite specimens, while causing no apparent external damage to the specimens. In contrast, oxidation at high temperatures causes dimensional changes and substantial surface damage within a narrow band (< 1 mm) near the exposed graphite surface, but leaves the interior of specimens with little or no changes in the pore structure. Based on these results it appears that weakening and degradation of mechanical properties of graphite materials produced by uniform oxidation at low temperatures is related to the massive development of fine pores in the oxidized zone. It was demonstrated that optical microscopy enhanced by AIA techniques allows accurate determination of oxidant penetration depth and of distribution of porosity in oxidized graphite materials.

  17. Electrode formulation to reduce weld metal hydrogen and porosity

    SciTech Connect

    Liu, S.; Olson, D.L.; Ibarra, S.

    1994-12-31

    Residual weld metal hydrogen is a major concern in high strength steel welding, especially when the weld is performed under high cooling rate conditions. In the case of underwater wet welding, weld metal porosity is also of importance because of the water environment. The control of both problems can be achieved by means of pyrochemical reactions in the weld pool. The hydrogen-oxygen reaction and carbon-oxygen reaction are fundamental in the control of residual hydrogen in the weld metal and the amount of gas pores entrapped. A simple model was proposed to estimate weld metal residual hydrogen content by monitoring the weld pool deoxidation reactions. Potent deoxidizers such as aluminum will first react with oxygen in the liquid weld pool, followed by other elements present such as silicon and manganese. Carbon and hydrogen will be the last ones to react with oxygen prior to the iron atoms. The Ellingham-Richardson diagram frequently applied in describing steel and iron making processes was used in the modeling. Following the sequence of deoxidation, the chemical make-up of the gas pores and the amount of each chemical species in the pores could be estimated. Carbon monoxide and hydrogen were determined to be the major components in the weld pores. To minimize the amount of weld metal porosity and residual hydrogen content, specially designed consumables that will control the oxygen potential of the weld pool must be developed.

  18. Turbulent boundary layer measurements over high-porosity surfaces

    NASA Astrophysics Data System (ADS)

    Efstathiou, Christoph; Luhar, Mitul

    2016-11-01

    Porous surfaces are ubiquitous across a variety of turbulent boundary layer flows of scientific and engineering interest. While turbulent flows over smooth and rough walls have been studied extensively, experimental measurements over porous walls have thus far focused on packed beds, which are limited in porosity (Φ = 0 . 3 - 0 . 5) by their geometry. The current project seeks to address this limitation. A two-component laser doppler velocimeter (LDV) is used to generate velocity measurements in turbulent boundary layer flows over commercially available reticulated foams and 3D-printed porous media at Reynolds number Reθ 3000 - 4000 . Smooth wall profiles for mean and turbulent quantities are compared to data over substrates with porosity Φ > 0 . 8 and average pore sizes in the range 0.4-2.5mm (corresponding to 8 - 50 viscous units). Previous analytical and simulation efforts indicate that the effects of porous substrates on boundary layer flows depend on a modified Reynolds number defined using the length scale √{ κ}, where κ is substrate permeability. A custom permeameter is currently being developed to estimate κ for the substrates tested in the boundary layer experiments.

  19. Effect of shelter porosity on downwind flow characteristics

    NASA Astrophysics Data System (ADS)

    Nosek, Š.; Kellnerová, R.; Jurčáková, K.; Jaňour, Z.; Chaloupecká, H.; Jakubcová, M.

    2016-03-01

    Previous wind-tunnel studies were focused mainly on lonely standing windbreaks or wind fences with respect to their wind velocity reduction efficiency and effective shelter distance. In presented wind-tunnel study, we investigated the effects of a three different fence porosities (0.5, 0.25 and 0) embodied in a shelter-like building for coal convey by means of two-component Laser Doppler Anemometry (LDA). The turbulent flow characteristics behind the fences were compared with those performed without the fence. For characterization of the fence effectiveness we used following quantities: wind-speed and turbulence kinetic energy reduction, and time fractions of the turbulent coherent structures associated with the sediment transport (sweeps and outward interactions). Results from mentioned quantities revealed that for the case of embodied fence the shelter construction has significant impact on the flow characteristics behind. The fence of the 0.5 porosity has been indicated as the most shelter effective considering the studied quantities.

  20. Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

    NASA Astrophysics Data System (ADS)

    Vakifahmetoglu, Cekdar; Zeydanli, Damla; Innocentini, Murilo Daniel De Mello; Ribeiro, Fernanda Dos Santos; Lasso, Paulo Renato Orlandi; Soraru, Gian Domenico

    2017-01-01

    This work describes a simple technique to produce porous ceramics with aligned porosity having very high permeability and specific surface area. SiOC-based compositions were processed from blends of three types of preceramic polymer and a catalyst, followed by curing and pyrolysis. The heating applied from the bottom of molds promoted the nucleation, expansion and rising of gas bubbles, and the creation of a ceramic matrix with axially oriented channels interconnected by small round pores. The samples were analyzed by SEM, tomography, BET, water immersion porosimetry and permeation to gas flow. The resulting bodies presented levels of open porosity (69.9–83.4%), average channel diameter (0.59–1.25 mm) and permeability (0.56–3.83 × 10‑9 m2) comparable to those of ceramic foams and honeycomb monoliths, but with specific surface area (4.8–121.9 m2/g) typical adsorbents, enabling these lotus-type ceramics to be advantageously used as catalytic supports and adsorption components in several environmental control applications.

  1. Kinetic-Impact Asteroid Defense: Dependence on Porosity and Composition

    NASA Astrophysics Data System (ADS)

    Gisler, G. R.; Ferguson, J. M.; Plesko, C. S.; Weaver, R.

    2015-12-01

    In this work we study the deflection of hazardous near-earth asteroids using a kinetic impactor. The momentum delivered to the asteroid can be greater than the momentum of the impactor because of the reaction force produced by ablation from the impact crater. We use an adaptive-mesh hydrocode to study the momentum-enhancement factor, or beta, varying the assumptions regarding the equation of state, strength, and porosity of the target. Spall from the back side of the asteroid, which partly counters the favorable effect of ablation, is also included in the calculations. The efficiency is shown to be most strongly dependent on the asteroid's porosity, which unfortunately is the most difficult quantity to obtain via remote observations. This study is applied both to the proposed deflection of the 150-meter diameter moon of the binary asteroid 65803 Didymos by the AIDA/DART mission, and to the potential deflection of the 492-meter diameter asteroid 101955 Bennu, which has some possible Earth impacts late in the 22nd century, and is the target of the planned OSIRIS-Rex mission. Figures of merit from both these studies include the bulk momentum imparted to the asteroid and the degree to which the asteroid is disrupted. (LA-UR-15-26214)

  2. Gradient-Hierarchic-Aligned Porosity SiOC Ceramics

    PubMed Central

    Vakifahmetoglu, Cekdar; Zeydanli, Damla; Innocentini, Murilo Daniel de Mello; Ribeiro, Fernanda dos Santos; Lasso, Paulo Renato Orlandi; Soraru, Gian Domenico

    2017-01-01

    This work describes a simple technique to produce porous ceramics with aligned porosity having very high permeability and specific surface area. SiOC-based compositions were processed from blends of three types of preceramic polymer and a catalyst, followed by curing and pyrolysis. The heating applied from the bottom of molds promoted the nucleation, expansion and rising of gas bubbles, and the creation of a ceramic matrix with axially oriented channels interconnected by small round pores. The samples were analyzed by SEM, tomography, BET, water immersion porosimetry and permeation to gas flow. The resulting bodies presented levels of open porosity (69.9–83.4%), average channel diameter (0.59–1.25 mm) and permeability (0.56–3.83 × 10−9 m2) comparable to those of ceramic foams and honeycomb monoliths, but with specific surface area (4.8–121.9 m2/g) typical adsorbents, enabling these lotus-type ceramics to be advantageously used as catalytic supports and adsorption components in several environmental control applications. PMID:28106140

  3. Control of reservoir porosity and permeability by original depositional fabric

    SciTech Connect

    Ruppel, S.C.

    1988-01-01

    The Emma San Andres field exhibits many of the classic signs of a depleted reservoir including declining annual production rates and high water cuts. By the end of 1986, oil production from the Emma reservoir, more than 19 million bbl, totaled nearly 100% of the estimated ultimate recovery. Recent studies, however, indicate that as much as 25 million bbl of recoverable mobile oil still remain in the reservoir. These studies also indicate that the observed poor recovery efficiency (32%, typical for San Andres/Grayburg reservoirs) is due to reservoir heterogeneity caused primarily by variations in original depositional fabric. Two distinct porosity intervals are recognized in the Emma reservoir. The lower interval is composed of fusulinid packstone/wackestone that contains moldic and intercrystalline porosity and low (average 2 md) permeabilities. These deposits are continuous and relatively uniform throughout the area; net pay in this zone is controlled primarily by the field structure, a low-relief northwest-trending anticline. Comparison of production data with faces mapping suggests that most oil production has been controlled by the distribution of skeletal grainstone and not by structure. Effective exploitation of this remaining mobile oil must include selective completion and injection programs based on variations in the distribution of skeletal grainstone. The absence of significant production from local grainstone thicks, for example, points to inefficient drainage in several parts of the field.

  4. Thermal Performance Evaluation of Walls with Gas Filled Panel Insulation

    SciTech Connect

    Shrestha, Som S.; Desjarlais, Andre Omer; Atchley, Jerald Allen

    2014-11-01

    Gas filled insulation panels (GFP) are very light weight and compact (when uninflated) advanced insulation products. GFPs consist of multiple layers of thin, low emittance (low-e) metalized aluminum. When expanded, the internal, low-e aluminum layers form a honeycomb structure. These baffled polymer chambers are enveloped by a sealed barrier and filled with either air or a low-conductivity gas. The sealed exterior aluminum foil barrier films provide thermal resistance, flammability protection, and properties to contain air or a low conductivity inert gas. This product was initially developed with a grant from the U.S. Department of Energy. The unexpanded product is nearly flat for easy storage and transport. Therefore, transportation volume and weight of the GFP to fill unit volume of wall cavity is much smaller compared to that of other conventional insulation products. This feature makes this product appealing to use at Army Contingency Basing, when transportation cost is significant compared to the cost of materials. The objective of this study is to evaluate thermal performance of walls, similar to those used at typical Barracks Hut (B-Hut) hard shelters, when GFPs are used in the wall cavities. Oak Ridge National Laboratory (ORNL) tested performance of the wall in the rotatable guarded hotbox (RGHB) according to the ASTM C 1363 standard test method.

  5. New method for quantification of vuggy porosity from digital optical borehole images as applied to the karstic Pleistocene limestone of the Biscayne aquifer, southeastern Florida

    USGS Publications Warehouse

    Cunningham, K.J.; Carlson, J.I.; Hurley, N.F.

    2004-01-01

    Vuggy porosity is gas- or fluid-filled openings in rock matrix that are large enough to be seen with the unaided eye. Well-connected vugs can form major conduits for flow of ground water, especially in carbonate rocks. This paper presents a new method for quantification of vuggy porosity calculated from digital borehole images collected from 47 test coreholes that penetrate the karstic Pleistocene limestone of the Biscayne aquifer, southeastern Florida. Basically, the method interprets vugs and background based on the grayscale color of each in digital borehole images and calculates a percentage of vuggy porosity. Development of the method was complicated because environmental conditions created an uneven grayscale contrast in the borehole images that makes it difficult to distinguish vugs from background. The irregular contrast was produced by unbalanced illumination of the borehole wall, which was a result of eccentering of the borehole-image logging tool. Experimentation showed that a simple, single grayscale threshold would not realistically differentiate between the grayscale contrast of vugs and background. Therefore, an equation was developed for an effective subtraction of the changing grayscale contrast, due to uneven illumination, to produce a grayscale threshold that successfully identifies vugs. In the equation, a moving average calculated around the circumference of the borehole and expressed as the background grayscale intensity is defined as a baseline from which to identify a grayscale threshold for vugs. A constant was derived empirically by calibration with vuggy porosity values derived from digital images of slabbed-core samples and used to make the subtraction from the background baseline to derive the vug grayscale threshold as a function of azimuth. The method should be effective in estimating vuggy porosity in any carbonate aquifer. ?? 2003 Published by Elsevier B.V.

  6. Defect-enhanced void filling and novel filled phases of open-structure skutterudites

    DOE PAGES

    Xi, Lili; Qiu, Yuting; Shi, Xun; ...

    2015-05-14

    Here, we report the design of novel filled CoSb3 skutterudite phases based on a combination of filling and Sb-substituted Ga/In defects. Ga/In doped skutterudite phases with Li-, Nd-, and Sm-fillings can be formed via this strategy, which can have relatively wider ranges of carrier concentration than other conventional filled skutterudite phases.

  7. 30 CFR 816.72 - Disposal of excess spoil: Valley fills/head-of-hollow fills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... incorporated into the design and construction of the fill as follows. (1) The fill shall have, along the... spoil fill and from seeps and springs in the foundation of the disposal area. Rocks used in the rock... maintained at the head of the fill during and after construction, to intercept surface runoff and...

  8. Defect-enhanced void filling and novel filled phases of open-structure skutterudites

    SciTech Connect

    Xi, Lili; Qiu, Yuting; Shi, Xun; Zhang, Wenqing; Chen, Lidong; Singh, David J.; Yang, Jihui

    2015-05-14

    Here, we report the design of novel filled CoSb3 skutterudite phases based on a combination of filling and Sb-substituted Ga/In defects. Ga/In doped skutterudite phases with Li-, Nd-, and Sm-fillings can be formed via this strategy, which can have relatively wider ranges of carrier concentration than other conventional filled skutterudite phases.

  9. Dolomitization and porosity development in the middle and upper Wabamun Group, southeast Peace River Arch, Alberta, Canada

    SciTech Connect

    Saller, A.H.; Yaremko, K.

    1994-09-01

    Dolomitization and fracturing are critical to porosity development in most Wabamun Group reservoirs in the southern part of the Peace River arch. Cores from Peoria, Normandville, and Eaglesham fields and adjacent areas were examined to determine the relationship between depositional facies, dolomitization, fracturing, and porosity. Three-dimensional (3-D) seismic data indicate that most upper Wabamun dolomites are coincident with mound-like structural highs at the top of the Wabamun, with structural relief due largely to differential compaction between dolomite and adjacent limestone. When this depositional/diagenetic model for dolomitization was integrated into 3-D seismic interpretations, Canadian Occidental`s discovery rate in the Wabamun increased from approximately 25 to 80%. The early dolomite is facies, fabric, and mineralogy selective with some burrow fills and aragonitic mollusks being preferentially dolomitized in dolomitic limestones. Most fracturing occurred after early, replacive Dolornitization. Late dolomitization, karst-like dissolution and collapse apparently were localized near the margins of the early dolomites where adjacent limestones were dolomitized or dissolved. Dissolution of calcite in partially dolomitized limestones resulted in geopetal accumulations of dolomite rhombs (porous sucrosic dolomite) in some fractures and burrow fills. Hydrothermal fluids apparently moved updip through the underlying Winterburn and/or Leduc formations, and then upward through porous, early dolomites in the Wabamun, causing Dolomitization of adjacent limestones and karst-like dissolution. Stable oxygen isotope ratios of the dolomites are quite variable ({delta}{sup 18}O ranges from -2.0 to -11.4{per_thousand}, PDB), supporting multiple stages of dolomitization during progressive burial.

  10. Investigation and calculation of filling factor of SnO2 inverse opal

    NASA Astrophysics Data System (ADS)

    Wang, Jinquan; Wu, Shimin; Ji, Xiaoyuan; Li, Jinpeng; Zhang, Rong; Zhang, Ming

    2016-04-01

    In the process of preparing inverse opal, the structure of inverse opal is affected by many factors, and the filling factor of inverse opal is difficult to directly test. In this paper, SnO2 inverse opal was prepared with the sol-gel method by cooperative opal template. The repetition times of the infiltrating precursor into the opal templates were investigated in detail. The band-gap positions of SnO2 inverse opal were tested. In order to prepare perfect inverse opal structure, the filling quantity of the precursor is greater, as the diameter of the PS microsphere of opal is bigger. The filling factor of air in inverse opal can be calculated with a formula derived from Bragg’s law. For inverse opal, the filling factor of air in inverse opal gradually enlarges as the diameter of the void increases.

  11. Numerical analysis of heat transfer by conduction and natural convection in loose-fill fiberglass insulation--effects of convection on thermal performance

    SciTech Connect

    Delmas, A.A.; Wilkes, K.E.

    1992-04-01

    A two-dimensional code for solving equations of convective heat transfer in porous media is used to analyze heat transfer by conduction and convection in the attic insulation configuration. The particular cases treated correspond to loose-fill fiberglass insulation, which is characterized by high porosity and air permeability. The effects of natural convection on the thermal performance of the insulation are analyzed for various densities, permeabilities, and thicknesses of insulation. With convection increasing the total heat transfer through the insulation, the thermal resistance was found to decrease as the temperature difference across the insulating material increases. The predicted results for the thermal resistance are compared with data obtained in the large-scale climate simulator at the Roof Research Center using the attic test module, where the same phenomenon has already been observed. The way the wood joists within the insulation influence the start of convection is studied for differing thermophysical and dynamic properties of the insulating material. The presence of wood joists induces convection at a lower temperature difference.

  12. A comparison of estimated and calculated effective porosity

    NASA Astrophysics Data System (ADS)

    Stephens, Daniel B.; Hsu, Kuo-Chin; Prieksat, Mark A.; Ankeny, Mark D.; Blandford, Neil; Roth, Tracy L.; Kelsey, James A.; Whitworth, Julia R.

    Effective porosity in solute-transport analyses is usually estimated rather than calculated from tracer tests in the field or laboratory. Calculated values of effective porosity in the laboratory on three different textured samples were compared to estimates derived from particle-size distributions and soil-water characteristic curves. The agreement was poor and it seems that no clear relationships exist between effective porosity calculated from laboratory tracer tests and effective porosity estimated from particle-size distributions and soil-water characteristic curves. A field tracer test in a sand-and-gravel aquifer produced a calculated effective porosity of approximately 0.17. By comparison, estimates of effective porosity from textural data, moisture retention, and published values were approximately 50-90% greater than the field calibrated value. Thus, estimation of effective porosity for chemical transport is highly dependent on the chosen transport model and is best obtained by laboratory or field tracer tests. Résumé La porosité effective dans les analyses de transport de soluté est habituellement estimée, plutôt que calculée à partir d'expériences de traçage sur le terrain ou au laboratoire. Les valeurs calculées de la porosité effective au laboratoire sur trois échantillons de textures différentes ont été comparées aux estimations provenant de distributions de taille de particules et de courbes caractéristiques sol-eau. La concordance était plutôt faible et il semble qu'il n'existe aucune relation claire entre la porosité effective calculée à partir des expériences de traçage au laboratoire et la porosité effective estimée à partir des distributions de taille de particules et de courbes caractéristiques sol-eau. Une expérience de traçage de terrain dans un aquifère de sables et de graviers a fourni une porosité effective calculée d'environ 0,17. En comparaison, les estimations de porosité effective de données de

  13. Experimental determination of the filling coefficient for an aspirated spark-ignition engine

    NASA Astrophysics Data System (ADS)

    Raţiu, S.; Alexa, V.; Kiss, I.; Cioată, V.

    2017-01-01

    This study aims at determining, by experiment, the filling coefficient of a spark-ignition, normal aspirated engine, with carburettor. For this purpose, a pilot plant was designed for measuring the pressure at various points on the route, simulating a stationary air flow regime by means of a vacuum pump. Measurements were made for various lifting heights of the intake valve and various opening positions of the throttle body, thus highlighting how their influence on the pressure loss and on the filling coefficient.

  14. Effect of Porosity on Deformation, Damage, and Fracture of Cast Steel

    NASA Astrophysics Data System (ADS)

    Hardin, R. A.; Beckermann, C.

    2013-12-01

    A combined experimental and computational study is performed to investigate the effect of centerline shrinkage porosity on deformation, damage, and fracture of cast steel under tensile testing. Steel plates containing shrinkage porosity are cast in sand molds, machined into test coupons, and tensile tested to fracture. The average volumetric porosity in the gage section of the specimens with porosity ranges from 0.10 to 0.27 pct. Ductility in the test castings with porosity is markedly reduced with the percent elongation data ranging from 12.8 to 19.6 pct; vs 22 pct elongation for the sound material. Radiographic imaging is used to measure and reconstruct the porosity field in the test specimens. The reconstructed porosity field is then used in a finite-element stress analysis simulating the tensile testing. Local elastic properties are reduced according to the porosity fraction present. Porous metal plasticity theory is used to model the damage due to porosity and the fracture. Good agreement is obtained between the measured and predicted stress-strain curves and fracture behaviors. The reduction in ductility is predicted well by comparing the measured and the simulated elongations. The computational modeling approach used in this study allows for a detailed evaluation of the effect of porosity, including its size, shape, and location, on the fracture behavior of steel castings.

  15. Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs.

    PubMed

    Tanaka, Kohei; Zelenitsky, Darla K; Therrien, François

    2015-01-01

    Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1) covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes), and 2) open nests, in which eggs are exposed in the nest and brooded (as in most birds). Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity) of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1) covered nests are likely the primitive condition for dinosaurs (and probably archosaurs), and 2) open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids) were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment. Open nests

  16. Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs

    PubMed Central

    2015-01-01

    Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1) covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes), and 2) open nests, in which eggs are exposed in the nest and brooded (as in most birds). Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity) of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1) covered nests are likely the primitive condition for dinosaurs (and probably archosaurs), and 2) open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids) were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment. Open nests

  17. Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating

    NASA Astrophysics Data System (ADS)

    Du, Chao; Wang, Qi; Zhao, Yong; Li, Jin

    2017-03-01

    A high sensitivity measurement method for temperature has been proposed and investigated based on an isopropanol-filled photonic crystal fiber long period grating (PCF-LPG). Due to the high thermo-optic coefficient (TOC) of isopropanol, the sensitivity of the proposed temperature sensor could be effectively improved by filling isopropanol in the air waveguides of PCF. It can be found that the resonant dip will be split in two dips after filling isopropanol and the two dips have different sensitivities to surrounding temperature. Because of PCF-LPG is sensitive to the refractive index (RI) of internal filled liquid, the isopropanol-filled PCF-LPG temperature sensor has a high sensitivities of 1.356 nm/°C in the range of 20-50 °C. The simplicity and the excellent performance of our proposed device make it potential for the applications of high-precision temperature measurement is required.

  18. Solid-Sorbent Air Sampler

    NASA Technical Reports Server (NTRS)

    Galen, T. J.

    1986-01-01

    Portable unit takes eight 24-hour samples. Volatile organic compounds in air collected for analysis by portable, self-contained sampling apparatus. Sampled air drawn through sorbent material, commercial porous polymer of 2, 3-diphenyl-p-phenylene oxide. High-boiling-point organic compounds adsorbed onto polymer, while low-boiling-point organics pass through and returned to atmosphere. Sampler includes eight sample tubes filled with polymeric sorbent. Organic compounds in atmosphere absorbed when air pumped through sorbent. Designed for checking air in spacecraft, sampler adaptable to other applications as leak detection, gas-mixture analysis, and ambient-air monitoring.

  19. A Streamline-Upwind Model for Filling Front Advection in Powder Injection Moulding

    NASA Astrophysics Data System (ADS)

    Larsen, Guillaume; Cheng, Zhi Qiang; Barriere, Thierry; Liu, Bao Sheng; Gelin, Jean-Claude

    2010-06-01

    The filling process of powder injection molding is modeled by the flows of two variably adjacent domains in the mold cavity. The feedstock is filled into the cavity while the air is expelled out by the injected feedstock [1]. Eulerian description is adopted. The filling patterns are determined by the solution of an advection equation, governed by the velocity field in both the feedstock flow and air flow [2]. In the real physics, the advance of filling front depends mainly on the flow of feedstock that locates behind the front. The flow of air in front of the injected material plays in fact no meaningful effect. However, the actual algorithm for solution of the advection equation takes equally the importance for both the flow of viscous feedstock and that of the slight air. Under such a condition, the injection flow of feedstock in simulation may be misdirected unrealistically by the velocity field in the air portion of the mold cavity. To correct this defect, an upwind scheme is proposed to reinforce the effect of upwind flow and reduce the effect of downstream flow. The present paper involves the investigation of an upwind algorithm for simulation of the filling state during powder injection molding. A Petrov-Galerkin upwind based method (SUPG) is adopted for numerical simulation of the transport equation instead of the Taylor-Galerkin method in previous work. In the proposed implementation of the Streamline-Upwind/Petrov-Galerkin (SUPG) approach. A stabilization method is used to prevent oscillations in the convection-dominated problems. It consists in the introduction of an artificial diffusion in streamline direction. Suitable modification of the test function is the important issue. It ensures the stable simulation of filling process and results in the more realistic prediction of filling patterns. The implementation of upwind scheme in mould filling state simulation, based on an advection equation and the whole velocity field of feedstock and air flow, makes

  20. Single-step fabrication of microfluidic channels filled with nanofibrous membrane using femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, K.

    2010-08-01

    In this paper, we demonstrate a new method of fabricating silicon microfluidic channels filled with a porous nanofibrous structure utilizing a femtosecond laser. The nanofibrous structure can act as a membrane used for microfiltration. This method allows us to generate both the microfluidic channel and the fibrous nanostructure in a single step under ambient conditions. Due to laser irradiation, a large number of nanoparticles ablate from the channel surface, and then aggregate and grow into porous nanofibrous structures and fill the channels. Energy dispersive x-ray spectroscopy (EDS) analysis was conducted to examine the oxygen concentration in the membrane structure. Our results demonstrated that by controlling the laser parameters including pulse repetition, pulse width and scanning speed, different microfluidic channels with a variety of porosity could be obtained.

  1. Controlling porosity in bridged polysilsesquioxanes through elimination reactions

    SciTech Connect

    McClain, M.D.; Loy, D.A.; Prabakar, S.

    1996-06-01

    The retro Diels-Alder reaction was used to modify porosity in hydrocarbon-bridged polysilsesquioxane gels. Microporous polysilsesquioxanes incorporating a thermally labile Diels-Alder adduct as the hydrocarbon bridging group were prepared by sol-gel polymerization of trans-2,3-bis(triethoxysilyl)norbornene. Upon heating the 2,3-norbornenylene-bridges polymers at temperatures above 250 C, the norbornenylene-bridging group underwent a retro Diels-Alder reaction losing cyclopentadiene and leaving behind a ethenylene-bridged polysilsesquioxane. Less than theoretical quantities of cyclopentadiene were volatilized indicating that some of the diene was either reacting with the silanol and olefinic rich material or undergoing oligomerization. Both scanning electron microscopy and nitrogen sorption porosimetry revealed net coarsening of pores (and reduction of surface area) in the materials with thermolysis.

  2. Porosity Controls Spread of Excitation in Tectorial Membrane Traveling Waves

    PubMed Central

    Sellon, Jonathan B.; Ghaffari, Roozbeh; Farrahi, Shirin; Richardson, Guy P.; Freeman, Dennis M.

    2014-01-01

    Cochlear frequency selectivity plays a key role in our ability to understand speech, and is widely believed to be associated with cochlear amplification. However, genetic studies targeting the tectorial membrane (TM) have demonstrated both sharper and broader tuning with no obvious changes in hair bundle or somatic motility mechanisms. For example, cochlear tuning of Tectb–/– mice is significantly sharper than that of TectaY1870C/+ mice, even though TM stiffnesses are similarly reduced relative to wild-type TMs. Here we show that differences in TM viscosity can account for these differences in tuning. In the basal cochlear turn, nanoscale pores of TectaY1870C/+ TMs are significantly larger than those of Tectb–/– TMs. The larger pore size reduces shear viscosity (by ∼70%), thereby reducing traveling wave speed and increasing spread of excitation. These results demonstrate the previously unrecognized importance of TM porosity in cochlear and neural tuning. PMID:24655516

  3. Superabsorbent, High Porosity, PAMPS-Based Hydrogels through Emulsion Templating.

    PubMed

    Kovačič, Sebastijan; Silverstein, Michael S

    2016-09-26

    Swell! Superabsorbent, mechanically robust, high-porosity hydrogels based on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) have been successfully synthesized by templating within high internal phase emulsions (HIPEs). These hydrogel polyHIPEs (HG-PHs) exhibit unusually high uptakes of water and of artificial urine through structure- and crosslinking-dependent hydrogel-swelling-driven void expansion. An HG-PH with 3.1 mmol g(-1) of highly accessible sulfonic acid groups exhibits a 7 meq NaOH ion exchange capacity per gram polymer and rapid dye absorption. The highly swollen HG-PHs do not fail at compressive strains of up to 60%, they retain water and recover their shapes upon the removal of stress. Unusually, the dry hydrogels have relatively high compressive moduli and achieve relatively high stresses at 70% strain.

  4. ASTROMETRIC MASSES OF 26 ASTEROIDS AND OBSERVATIONS ON ASTEROID POROSITY

    SciTech Connect

    Baer, James; Chesley, Steven R.; Matson, Robert D. E-mail: steve.chesley@jpl.nasa.gov

    2011-05-15

    As an application of our recent observational error model, we present the astrometric masses of 26 main-belt asteroids. We also present an integrated ephemeris of 300 large asteroids, which was used in the mass determination algorithm to model significant perturbations from the rest of the main belt. After combining our mass estimates with those of other authors, we study the bulk porosities of over 50 main-belt asteroids and observe that asteroids as large as 300 km in diameter may be loose aggregates. This finding may place specific constraints on models of main-belt collisional evolution. Additionally, we observe that C-group asteroids tend to have significantly higher macroporosity than S-group asteroids.

  5. Spark plasma sintering and porosity studies of uranium nitride

    NASA Astrophysics Data System (ADS)

    Johnson, Kyle D.; Wallenius, Janne; Jolkkonen, Mikael; Claisse, Antoine

    2016-05-01

    In this study, a number of samples of UN sintered by the SPS method have been fabricated, and highly pure samples ranging in density from 68% to 99.8%TD - corresponding to an absolute density of 14.25 g/cm3 out of a theoretical density of 14.28 g/cm3 - have been fabricated. By careful adjustment of the sintering parameters of temperature and applied pressure, the production of pellets of specific porosity may now be achieved between these ranges. The pore closure behaviour of the material has also been documented and compared to previous studies of similar materials, which demonstrates that full pore closure using these methods occurs near 97.5% of relative density.

  6. Discrimination of porosity and fluid saturation using seismic velocity analysis

    DOEpatents

    Berryman, James G.

    2001-01-01

    The method of the invention is employed for determining the state of saturation in a subterranean formation using only seismic velocity measurements (e.g., shear and compressional wave velocity data). Seismic velocity data collected from a region of the formation of like solid material properties can provide relatively accurate partial saturation data derived from a well-defined triangle plotted in a (.rho./.mu., .lambda./.mu.)-plane. When the seismic velocity data are collected over a large region of a formation having both like and unlike materials, the method first distinguishes the like materials by initially plotting the seismic velocity data in a (.rho./.lambda., .mu./.lambda.)-plane to determine regions of the formation having like solid material properties and porosity.

  7. Distribution of porosity and macrosegregation in slab steel ingot

    NASA Astrophysics Data System (ADS)

    Tkadleckova, M.; Jonsta, P.; Carbol, Z.; Susovsky, M.; Michalek, K.; Socha, L.; Sviželová, J.; Zwyrtek, J.

    2017-02-01

    The paper presents a new knowledge and experiences with verification and optimization of production technology of heavy slab ingot weighing 40 t from tool steel using the results of numerical modelling and of operational experiments at a steel plant in the company VÍTKOVICE HEAVY MACHINERY a.s. The final porosity, macrosegregation and the risk of cracks were predicted. Based on the results, the slab ingot can be used instead of the conventional heavy steel ingot. Also, the ratio, the chamfer, and the external shape of the wall of the new design of the slab ingot was improved, which enabled to reduce production costs while the internal quality of steel ingots was still maintained at very high level.

  8. Tunable Porosities and Shapes of Fullerene-Like Spheres

    PubMed Central

    Dielmann, Fabian; Fleischmann, Matthias; Heindl, Claudia; Peresypkina, Eugenia V; Virovets, Alexander V; Gschwind, Ruth M; Scheer, Manfred

    2015-01-01

    The formation of reversible switchable nanostructures monitored by solution and solid-state methods is still a challenge in supramolecular chemistry. By a comprehensive solid state and solution study we demonstrate the potential of the fivefold symmetrical building block of pentaphosphaferrocene in combination with CuI halides to switch between spheres of different porosity and shape. With increasing amount of CuX, the structures of the formed supramolecules change from incomplete to complete spherically shaped fullerene-like assemblies possessing an Ih-C80 topology at one side and to a tetrahedral-structured aggregate at the other. In the solid state, the formed nano-sized aggregates reach an outer diameter of 3.14 and 3.56 nm, respectively. This feature is used to reversibly encapsulate and release guest molecules in solution. PMID:25759976

  9. Porosity estimation of alumina samples based on resonant backscattering spectrometry

    NASA Astrophysics Data System (ADS)

    Mokhles Gerami, F.; Kakuee, O.; Mohammadi, S.

    2016-04-01

    In this work, columnar porous alumina samples were investigated using the 16O(α,α)16O resonance scattering at 3.045 MeV. If the incident energy is slightly above the resonance energy, a resonance peak appears in the energy spectra of the backscattered ions. The position and width of this peak for non-porous samples are mainly determined by the experimental setup, whilst for porous materials, the peak position shifts towards higher energies under certain conditions. This effect can be explained by the lower amount of material which the ions encounter along the backscattered trajectories. The energy shift of the resonance peak towards higher energies was revealed experimentally and discussed theoretically. The estimated porosities of the samples based on this energy shift were compared with those evaluated from the graphical analysis of the images obtained by field emission scanning electron microscopy.

  10. Porosity and permeability evolution of clay faults: in situ experiments

    NASA Astrophysics Data System (ADS)

    Henry, P.; Guglielmi, Y.; Seguy, S.; Lefevre, M.; Ghani, I.; Gent, G.; Castilla, R.; Gout, C.; Dick, P.; Nussbaum, C.; Durand, J.

    2015-12-01

    Fault models associating low permeability cores with high permeability damage zones are widely accepted, however, constitutive laws relating permeability with fault structure, stress, and strain remain poorly constrained. We here present preliminary results of hydromechanical experiments performed at the 10 m scale in fault zones in Toarcian and Aalenian black shale formations. Intact formations have a very low permeability (10-19 to 10-22 m2). One case (in IRSN's Tournemire Underground Research Laboratory) displays a porosity increase in and around the fault core and abundant veins and calcite cemented small faults in the damage zone. The other case (Mont Terri Swisstopo Underground Research Laboratory) displays a porosity decrease in the fault core zone and few veins. However, under the present stress state, the static permeability of the fractured zones at both locations is higher than that of the intact formation by up to 3 orders of magnitude. During borehole pressurization tests three regimes of permeability variations are observed. (1) Fracture permeability first increases progressively as a function of fluid pressure (2) When a threshold is reached, permeability further increases by 100 or more, but strain as well as permeability variations remain in most part reversible. (3) When a steady pressure is maintained in the injection borehole (from 20 minutes to several days) flow rate tends to decrease with time. These results show that high transient permeability may locally occur in a fault zone under conditions when most of the deformation is reversible, opening the possibility of transient fluid migration decoupled from slip along faults that are not favorably oriented. However, during one test, more than 1 mm of irreversible slip occurred along one of the main interfaces, associated with a sudden increase in flow rate (from 11 to more than 40 l/min). This suggests that when slip occurs, it could result in permeability variations that may remain difficult

  11. Controlled ceramic porosity and membrane fabrication via alumoxane nanoparticles

    NASA Astrophysics Data System (ADS)

    Jones, Christopher Daniel

    Carboxylate-alumoxanes, [Al(O)x(OH)y(O2CR) z]n, are organic substituted alumina nano-particles synthesized from boehmite in aqueous solution which are an inexpensive and environmentally-benign precursor for the fabrication of aluminum based ceramic bodies. The carboxylate-ligand on the alumoxane determines the morphology and the porosity of the derived alumina. Investigations of A-, MA-, MEA-, and MEEA-alumoxanes, were undertaken to determine the effects of these organic peripheries on the properties of the alumina at different sintering temperatures including the morphology, surface area, pore volume, pore size, pore size distribution, and crystal phase. The effects of physically or chemically mixing different carboxylate-alumoxanes were also investigated. The alumina derived from the thermolysis of the carboxylate-alumoxanes exhibits small pore diameters and narrow pore size distributions that are desirable for use in ceramic ultrafiltration membranes. In addition, it is possible to form alumina membranes with a range of pore sizes and porosity by changing the organic periphery. This lead to investigating the ability to produce asymmetric alumina filters with characteristics that at the lower end of the ultrafiltration range. The flux, permeability, molecular weight cut-off, roughness, and wettability of the asymmetric alumina membranes derived from carboxylate-alumoxanes are determined. Comparisons of these filters are made with commercially available filters. The ability to dope carboxylate-alumoxanes via a transmetallation reaction followed by thermolysis has previously shown to result in catalytically active alumina based materials. This lead to investigations into forming catalytically active membranes. Dip-coating aqueous solutions of the doped carboxylate-alumoxanes onto porous alumina supports, followed by thermolysis, resulted in the formation of doped-alumina asymmetric filters. In addition, a novel method to form surface-modified carboxylate

  12. Hayward Fault rocks: porosity, density, and strength measurements

    USGS Publications Warehouse

    Morrow, C.A.; Lockner, D.A.

    2001-01-01

    Porosity, density and strength measurements were conducted on rock samples collected from the Hayward Fault region in Northern California as part of the Hayward Fault Working Group’s efforts to create a working model of the Hayward Fault. The rocks included in this study were both fine and coarse grained gabbros, altered keratophyre, basalt, sandstone, and serpentinite from various rock formations adjacent to the Hayward Fault. Densities ranged from a low of 2.25 gm/cc (altered keratophyre) to 3.05 gm/cc (fine gabbro), with an average of 2.6 gm/cc, typical of many other rocks. Porosities were generally around 1% or less, with the exception of the sandstone (7.6%) and altered keratophyre (13.5%). Failure and frictional sliding tests were conducted on intact rock cylinders at room temperature under effective pressure conditions of up to 192 MPa, simulating depths of burial to 12 km. Axial shortening of the samples progressed at a rate of 0.1 µm/sec (fine samples) or 0.2 µm/sec (porous samples) for 6 mm of displacement. Velocity stepping tests were then conducted for an additional 2 mm of displacement, for a total of 8 mm. Both peak strength (usually failure strength) and frictional strength, determined at 8 mm of displacement, increased systematically with effective pressure. Coefficients of friction, based on the observed fracture angles, ranged from 0.6 to 0.85, consistent with Byerlee’s Law. Possible secondary influences on the strength of the Hayward rock samples may be surface weathering, or a larger number of pre-existing fractures due to the proximity to the Hayward Fault. All samples showed velocity strengthening, so that the average a-b values were all strongly positive. There was no systematic relation between a-b values and effective pressure. Velocity strengthening behavior is associated with stable sliding (creep), as observed in the shallow portions of the Hayward Fault.

  13. Classification of munition fill using laser acoustics

    SciTech Connect

    Rodriguez, J.G.; Blackwood, L.G.

    1997-08-01

    Identification of a munition fill is easier if one can determine if there is fill material present (empty versus full), and if so, the phase (solid or liquid) of the fill. Previous munition inspection efforts by the Idaho National Engineering and Environmental Laboratory (INEEL) determined that resonance information could determine the fill. A portable, noncontacting laser-acoustic system was developed by INEEL that uses a low-power laser system to measure the container`s vibration characteristics in response to an acoustic excitation. These vibration characteristics were shown to be functions of the fill material and munition geometry. The laser acoustic system was used to characterize the fill of over one hundred 155-mm munitions. Additional research and development using this system is being performed for the Mobile Munitions Assessment System.

  14. Filling of orbital fluid management systems

    NASA Technical Reports Server (NTRS)

    Merino, F.; Blatt, M. H.; Thies, N. C.

    1978-01-01

    A study was performed with three objectives: (1) analyze fluid management system fill under orbital conditions; (2) determine what experimentation is needed; and (3) develop an experimental program. The fluid management system was a 1.06m (41.7 in) diameter pressure vessel with screen channel device. Analyses were conducted using liquid hydrogen and N2O4. The influence of helium and autogenous pressurization systems was considered. Analyses showed that fluid management system fill will be more difficult with a cryogen than with an earth storable. The key to a successful fill with cryogens is in devising techniques for filling without vent liquid, and removing trapped vapor from the screen device at tank fill completion. This will be accomplished with prechill, fill, and vapor condensation processes. Refill will require a vent and purge process, to dilute the residual helium, prior to introducing liquid. Neither prechill, chill, nor purge processes will be required for earth storables.

  15. Grain-filling problem in 'super' rice.

    PubMed

    Yang, Jianchang; Zhang, Jianhua

    2010-01-01

    Modern rice (Oryza sativa L.) cultivars, especially the newly bred 'super' rice, have numerous spikelets on a panicle with a large yield capacity. However, these cultivars often fail to achieve their high yield potential due to poor grain-filling of later-flowering inferior spikelets (in contrast to the earlier-flowering superior spikelets). Conventional thinking to explain the poor grain-filling is the consequence of carbon limitation. Recent studies, however, have shown that carbohydrate supply should not be the major problem because they have adequate sucrose at their initial grain-filling stage. The low activities of key enzymes in carbon metabolism may contribute to the poor grain-filling. Proper field practices, such as moderate soil drying during mid- and late grain-filling stages, could solve some problems in poor grain-filling. Further studies are needed by molecular approaches to investigate the signal transport, the hormonal action, the gene expressions, and the biochemical processes in inferior spikelets.

  16. Effective use of fly ash slurry as fill material.

    PubMed

    Horiuchi, S; Kawaguchi, M; Yasuhara, K

    2000-09-15

    A lot of effort has been put into increasing coal ash utilization; however, 50% of total amount is disposed of on land and in the sea. Several attempts have been reported recently concerning slurried coal fly ash use for civil engineering materials, such as for structural fill and backfill. The authors have studied this issue for more than 15 years and reported its potential for (1) underwater fills, (2) light weight backfills, and (3) light weight structural fills, through both laboratory tests and construction works. This paper is an overview of the results obtained for slurry, focusing on the following. (1) Coal fly ash reclaimed by slurry placement shows lower compressibility, higher ground density, and higher strength than by the other methods. This higher strength increases stability against liquefaction during earthquake. (2) Higher stability of the fly ash ground formed by slurry placement is caused by higher density and its self-hardening property. (3) Stability of fly ash reclaimed ground can be increased by increasing density and also by strength enhancement by cement addition. (4) Technical data obtained through a man-made island construction project shows the advantages of fly ash slurry in terms of mechanical properties such as higher stability against sliding failure, sufficient ground strength, and also in terms of cost saving. (5) Concentration in leachates from the placed slurry is lower than the Japanese environmental law. (6) In order to enlarge the fly ash slurry application toward a lightweight fill, mixtures of air foam, cement and fly ash were examined. Test results shows sufficient durability of this material against creep failure. This material was then used as lightweight structural fill around a high-rise building, and showed sufficient quality. From the above data, it can be concluded that coal fly ash slurry can be effectively utilized in civil engineering projects.

  17. A dual-porosity reservoir model with a nonlinear coupling term

    SciTech Connect

    Zimmerman, R.W.; Chen, G.; Hadgu, T.; Bodvarsson, G.S.

    1992-09-01

    Since their introduction by Barenblatt et al. (1960), double-porosity models have been widely used for simulating flow in fractured reservoirs, such as geothermal reservoirs. In a dual-porosity system, the matrix blocks provide most of the storage of the reservoir, whereas the fractures provide the global transmissivity. Initially, most work on dual-porosity models emphasized the development of analytical solutions to idealized reservoir problems. Increasingly, the dual-porosity approach is being implemented by numerical reservoir simulators. Accurate numerical simulation of a dual-porosity problem often requires a prohibitively large number of computational cells in order to resolve the transient pressure gradients in the matrix blocks. We discuss a new dual-porosity model that utilizes a nonlinear differential equation to approximate the fracture/matrix interactions, When implemented into a numerical simulator, it eliminates the need to discretize the matrix blocks, and thereby allows more efficient simulation of reservoir problems.

  18. Secondary compaction after secondary porosity: Can it form a pressure seal

    SciTech Connect

    Weedman, S.D.; Brantley, S.L.; Albrecht, W. )

    1992-04-01

    Petrographic analysis of sandstones from the vicinity of a pressure seal (transition from normal to overpressure) at 5.5-km depth in the lower Tuscaloosa Formation in Louisiana documents local, high porosity above and below the seal. Packing analysis shows that compaction is greater in normally pressured, high-porosity sandstones than in overpressured, high-porosity sandstones; compaction in overpressured, high-porosity sandstones is similar to that in normally pressured, well-cemented sandstones. The authors propose that focused corrosive fluids created a zone of high secondary porosity, allowing further compaction that they call 'secondary compaction.' Secondary compaction is greater above the seal than below, suggesting that high-pressure fluid below the seal has preserved porosity and that the pressure seal became effective soon after dissolution of cement. Cuttings from the pressure-seal zone reveal an unusual texture of fragmented, pressure-solved grains and matrix, which may be a result of extensive secondary compaction.

  19. Study of Porosity on Titania Slag Obtained by Conventional Sintering and Thermal Plasma Process

    NASA Astrophysics Data System (ADS)

    Samal, S.

    2016-12-01

    This article investigates the development of porosity in titania-rich slag obtained by sintering via conventional and thermal plasma heating at 1000°C in inert atmosphere. The holder in the plasma reactor acted as the discharge anode confined within a hollow graphite cathode. Quantitative evaluation of the porosity in the conventionally sintered and plasma-sintered titania-rich slag was performed via pycnometry. Specifically, the physical dimension and morphology of the pores were characterized according to the area fraction, mean diameter, shape factor, and elongation factor. Under both conventional and thermal plasma heating conditions, porosity developed on the surface of titania-rich slag. The titania-rich slag obtained by two processes showed different porosity features in terms of the morphology and porosity. A lower porosity was observed in the plasma-sintered sample when compared with that obtained via conventional heating.

  20. Differences in bone-cement porosity by vacuum mixing, centrifugation, and hand mixing.

    PubMed

    Macaulay, William; DiGiovanni, Christopher W; Restrepo, Andres; Saleh, Khaled J; Walsh, Heather; Crossett, Lawrence S; Peterson, Margaret G E; Li, Stephen; Salvati, Eduardo A

    2002-08-01

    The mean pore size and percent porosity of vacuum-mixed cement were compared with centrifuged cement and cement hand mixed by skilled specialized operating room technicians. Centrifuged cement samples had the smallest mean pore size when compared with vacuum-mixed specimens. The mean pore size for the hand-mixed specimens was intermediate and not significantly different from the other 2 mixing techniques. Results were reversed, however, for mean percent porosity. Centrifuged cement had the highest percent porosity; vacuum-mixed cement, the lowest; and hand-mixed cement, intermediate. The porosity of vacuum-mixed Simplex P (Howmedica, Rutherford, NJ) bone-cement was similar from the initial to the remnant cement extruded from the cement gun. There was no reduced cement porosity with vacuum mixing or centrifugation as anticipated. Reversion to hand mixing by highly skilled technicians could result in a significant cost savings without negative effects on cement porosity.

  1. Tuning magnetoelectric coupling using porosity in multiferroic nanocomposites of ALD-grown Pb(Zr,Ti)O3 and templated mesoporous CoFe2O4

    NASA Astrophysics Data System (ADS)

    Chien, Diana; Buditama, Abraham N.; Schelhas, Laura T.; Kang, Hye Yeon; Robbennolt, Shauna; Chang, Jane P.; Tolbert, Sarah H.

    2016-09-01

    In this manuscript, we examine ways to create multiferroic composites with controlled nanoscale architecture. We accomplished this by uniformly depositing piezoelectric lead zirconate titanate (PZT) into templated mesoporous, magnetostrictive cobalt ferrite (CFO) thin films to form nanocomposites in which strain can be transferred at the interface between the two materials. To study the magnetoelectric coupling, the nanostructure was electrically poled ex situ prior to magnetic measurements. No samples showed a change in in-plane magnetization as a function of voltage due to substrate clamping. Out-of-plane changes were observed, but contrary to expectations based on total PZT volume fraction, mesoporous CFO samples partially filled with PZT showed more change in out-of-plane magnetization than the sample with fully filled pores. This result suggests that residual porosity in the composite adds mechanical flexibility and results in greater magnetoelectric coupling.

  2. Effect of porosity on electrical conduction of simulated nanostructures by Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Dariani, R. S.; Abbas Hadi, N.

    2016-09-01

    Electrical conduction of deposited nanostructures is studied by oblique angle deposition. At first, a medium is simulated as nanocolumns by Monte Carlo method, then the effects of porosity on electron transport in 1D and 2D are investigated. The results show that more electrons transfer in media with low porosity, but with increasing porosity, the distance between nanocolumns expands and less electrons transfer. Therefore, the transport current reduces at the surface.

  3. Mekong Floods Fill Tonle Sap

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The monsoon season in Southeast Asia brings recurring, often devastating floods to countries in the region, but these floods also play a necessary role in the region's water cycle. These MODIS images centered on Cambodia reveal extensive flooding of the Mekong River, which comes in from Laos in the north, to the right of center in the images, and flows south through Cambodia and southeast through Vietnam to empty into the South China Sea. The true-color image shows the brownish, sediment-laden floodwaters filling the Mekong Delta in southern Cambodia and Vietnam on September 15, 2001. The false color image above has been enhanced to bring out the contrast between the floodwaters and the lands, with sediment-carrying floodwaters in purple. Sediment can be seen flowing into the South China Sea as well. This year's floods have affected over a million people, and 100 people have been killed in Vietnam alone. The monsoon floods bring not only devastation, but renewal. The large body of water just left of center in Cambodia is the Tonle Sap. This shallow lake plays a changing role in the regional water cycle. During the dry season, the stream-fed Tonle Sap drains via the Tonle Sab River into the Mekong River. During the wet season (June-November), flooding of the Mekong reverses the course of the Tonle Sab, roughly tripling the lake's size from about 3000 km2 to about 10,000. When the dry season returns, the lake once again begins to drain into the Mekong Delta, where it provides a flow of fresh water that balances the intrusion of salty seawater into the delta's agricultural lands. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  4. Fabrication of High-Porosity Lotus-Type Porous Aluminum in Vacuum

    NASA Astrophysics Data System (ADS)

    Liu, Xiaobang; Li, Yanxiang; He, Yun

    2017-03-01

    Lotus-type porous aluminums with porosities from 10 to 26 pct were fabricated with the Bridgman-type directional solidification method (Gasar). A vacuum atmosphere is critical to obtain high-porosity lotus-type porous aluminum by the Gasar process. The lotus-type porous aluminum was directionally solidified under a pure hydrogen pressure of 0.2 to 16 kPa. The influence of hydrogen pressure on the porosity and pore size in vacuum was investigated. The porosity and pore size increase with decreasing hydrogen pressure, but there exists a maximum porosity at some critical hydrogen pressure. Since a low hydrogen pressure is adopted, the effect of capillary pressure and hydrostatic pressure on the porosity becomes important. With the decreasing of hydrogen pressure, the influence of hydrostatic pressure and capillary pressure on porosity becomes stronger and stronger. The influence of melt height, which is proportional hydrostatic pressure, on porosity and pore size was investigated. The calculated porosities considering capillary pressure and hydrostatic pressure are in good agreement with experimental results.

  5. Fabrication of High-Porosity Lotus-Type Porous Aluminum in Vacuum

    NASA Astrophysics Data System (ADS)

    Liu, Xiaobang; Li, Yanxiang; He, Yun

    2017-01-01

    Lotus-type porous aluminums with porosities from 10 to 26 pct were fabricated with the Bridgman-type directional solidification method (Gasar). A vacuum atmosphere is critical to obtain high-porosity lotus-type porous aluminum by the Gasar process. The lotus-type porous aluminum was directionally solidified under a pure hydrogen pressure of 0.2 to 16 kPa. The influence of hydrogen pressure on the porosity and pore size in vacuum was investigated. The porosity and pore size increase with decreasing hydrogen pressure, but there exists a maximum porosity at some critical hydrogen pressure. Since a low hydrogen pressure is adopted, the effect of capillary pressure and hydrostatic pressure on the porosity becomes important. With the decreasing of hydrogen pressure, the influence of hydrostatic pressure and capillary pressure on porosity becomes stronger and stronger. The influence of melt height, which is proportional hydrostatic pressure, on porosity and pore size was investigated. The calculated porosities considering capillary pressure and hydrostatic pressure are in good agreement with experimental results.

  6. Numerical scheme to complete a compressible gas flow in variable porosity media

    NASA Astrophysics Data System (ADS)

    Rochette, D.; Clain, S.; Buffard, T.

    2005-05-01

    We present an approximate Riemann solver coupled with a finite volume method to compute non conservative Euler equations in variable porosity media using ideal gas state law. The non conservative term is numerically taken into account from an original idea of LeRoux (1998) but here Riemann problems at each interface of the mesh are linearized using a VFRoe approach. The main goal is the resolution of the non conservative system even if the porosity is discontinuous. Stationary solutions are determined with continuous and discontinuous porosity in order to test the numerical scheme and computations of gas shock subsonic wave moving in a non continuous porosity medium are presented.

  7. Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels

    NASA Astrophysics Data System (ADS)

    Yun, Di; Yacout, Abdellatif M.; Stan, Marius; Bauer, Theodore H.; Wright, Arthur E.

    2014-05-01

    Evolution of porosity generated in metallic U-Zr fuel irradiated in fast spectrum reactors leads to changes in fuel properties and impacts important phenomena such as heat transport and constituent redistribution. The porosity is generated as a result of the accumulation of fission gases and is affected by the possible bond sodium infiltration into the fuel. Typically, the impact of porosity development on properties, such as thermal conductivity, is accounted for through empirical correlations that are dependent on porosity and infiltrated sodium fractions. Currently available simulation tools make it possible to take into account fuel 3-D porosity distributions, potentially eliminating the need for such correlations. This development allows for a more realistic representation of the porosity evolution in metallic fuel and creates a framework for truly mechanistic fuel development models. In this work, COMSOL multi-physics simulation platform is used to model 3-D porosity distributions and simulate heat transport in metallic U-10Zr fuel. Available experimental data regarding microstructural evolution of fuel that was irradiated in EBR-II and associated phase stability information are used to guide the simulation. The impact of changes in porosity characteristics on material properties is estimated and the results are compared with calculated temperature distributions. The simulations demonstrate the developed capability and importance of accounting for detailed porosity distribution features for accurate fuel performance evaluation.

  8. Validation of a stochastic digital packing algorithm for porosity prediction in fluvial gravel deposits

    NASA Astrophysics Data System (ADS)

    Liang, Rui; Schruff, Tobias; Jia, Xiaodong; Schüttrumpf, Holger; Frings, Roy M.

    2015-11-01

    Porosity as one of the key properties of sediment mixtures is poorly understood. Most of the existing porosity predictors based upon grain size characteristics have been unable to produce satisfying results for fluvial sediment porosity, due to the lack of consideration of other porosity-controlling factors like grain shape and depositional condition. Considering this, a stochastic digital packing algorithm was applied in this work, which provides an innovative way to pack particles of arbitrary shapes and sizes based on digitization of both particles and packing space. The purpose was to test the applicability of this packing algorithm in predicting fluvial sediment porosity by comparing its predictions with outcomes obtained from laboratory measurements. Laboratory samples examined were two natural fluvial sediments from the Rhine River and Kall River (Germany), and commercial glass beads (spheres). All samples were artificially combined into seven grain size distributions: four unimodal distributions and three bimodal distributions. Our study demonstrates that apart from grain size, grain shape also has a clear impact on porosity. The stochastic digital packing algorithm successfully reproduced the measured variations in porosity for the three different particle sources. However, the packing algorithm systematically overpredicted the porosity measured in random dense packing conditions, mainly because the random motion of particles during settling introduced unwanted kinematic sorting and shape effects. The results suggest that the packing algorithm produces loose packing structures, and is useful for trend analysis of packing porosity.

  9. Heat stress in chemical protective clothing: porosity and vapour resistance.

    PubMed

    Havenith, George; den Hartog, Emiel; Martini, Svein

    2011-05-01

    Heat strain in chemical protective clothing is an important factor in industrial and military practice. Various improvements to the clothing to alleviate strain while maintaining protection have been attempted. More recently, selectively permeable membranes have been introduced to improve protection, but questions are raised regarding their effect on heat strain. In this paper the use of selectively permeable membranes with low vapour resistance was compared to textile-based outer layers with similar ensemble vapour resistance. For textile-based outer layers, the effect of increasing air permeability was investigated. When comparing ensembles with a textile vs. a membrane outer layer that have similar heat and vapour resistances measured for the sum of fabric samples, a higher heat strain is observed in the membrane ensemble, as in actual wear, and the air permeability of the textile version improves ventilation and allows better cooling by sweat evaporation. For garments with identical thickness and static dry heat resistance, but differing levels of air permeability, a strong correlation of microclimate ventilation due to wind and movement with air permeability was observed. This was reflected in lower values of core and skin temperatures and heart rate for garments with higher air permeability. For heart rate and core temperature the two lowest and the two highest air permeabilities formed two distinct groups, but they did not differ within these groups. Based on protection requirements, it is concluded that air permeability increases can reduce heat strain levels allowing optimisation of chemical protective clothing. STATEMENT OF RELEVANCE: In this study on chemical, biological, radiological and nuclear (CBRN) protective clothing, heat strain is shown to be significantly higher with selectively permeable membranes compared to air permeable ensembles. Optimisation of CBRN personal protective equipment needs to balance sufficient protection with reduced heat

  10. Influence of structural-phase state of ferritic-martensitic steels on the helium porosity development

    NASA Astrophysics Data System (ADS)

    Chernov, I. I.; Staltsov, M. S.; Kalin, B. A.; Bogachev, I. A.; Guseva, L. Yu; Dzhumaev, P. S.; Emelyanova, O. V.; Drozhzhina, M. V.; Manukovsky, K. V.; Nikolaeva, I. D.

    2016-04-01

    Transmission electron microscopy (TEM) has been used to study the effect of the initial structural-phase state (SPhS) of ferritic-martensitic steels EK-181, EP-450 and EP-450- ODS (with 0.5 wt.% nanoparticles of Y2O3) on the of helium porosity formation and gas swelling. Different SPhS of steel EK-181 was produced by water quenching, annealing, normalizing plus tempered, intensive plastic deformation by torsion (HPDT). Irradiation was carried out by He+-40 keV ions at 923 K up to fluence of 5-1020 He+/m2. It is shown that the water quenching causes the formation of uniformly distributed small bubbles (d¯ ∼ 2 nm) of the highest density (ρ∼ 1025 m-3). After normalization followed by tempering as well as after annealing bubbles distribution is highly non-uniform both by volume and in size. Very large faceted bubbles (pre-equilibrium gas-filled voids) are formed in ferrite grains resulting in high level of gas swelling of the irradiated layer with S = 4,9 ± 1,2 and 3.8 ± 0.9% respectively. Nano- and microcrystalline structure created by HPDT completely degenerate at irradiation temperature and ion irradiation formed bubbles of the same parameters as in the annealed steel. Bubbles formed in EP-450-ODS steel are smaller in size and density, which led to a decrease of helium swelling by 4 times (S = 0.8 ± 0.2%) as compared to the swelling of the matrix steel EP-450 (S = 3.1 ± 0.7%).

  11. Determination of interstitial water chemistry and porosity in consolidated aquifer materials by diffusion equilibrium-exchange.

    PubMed

    Spence, Michael J; Thornton, Steven F; Bottrell, Simon H; Spence, Keith H

    2005-02-15

    Diffusion equilibrium exchange (DEE) is presented as a novel, practical alternative to centrifugation for the recovery and chemical analysis of interstitial water in contaminated core samples from consolidated rocks and aquifers. The methodology is suitable for sampling organic and inorganic compounds, including redox sensitive species such as SO4(2-), NO3-, NO2-, Mn(II), Fe(II), and sulfide (HS-). DEE also permits analyte extraction from kilogram quantities of core, which avoids extended centrifugation or sample amalgamation and provides analyte masses appropriate for stable isotope analysis. The procedure involves simple and rapid on-site sectioning of representative core samples, which are preserved in the field by storage in airtight bottles filled with deoxygenated deionized water containing a conservative tracer (Br-). Equilibration times for individual solutes can be estimated in advance to reduce the need for time-series analysis; for an effective diffusion coefficient of 2.5 x 10(-10) m2 s(-1) (Br- in chalk rock) equilibration was >90% completed after 30 h, consistent with the predicted equilibration time. The DEE method presented minimizes sampling errors from temperature changes, oxidation of reduced chemical species, and loss of volatile compounds, which can occur with other interstitial water sampling techniques. It also gives superior resolution of in situ solute distributions and geochemical processes in consolidated sediments than centrifugation and can provide estimates of aquifer porosity in core samples. Laboratory experiments using chalk rock core and simulated extraction procedures confirm the superior performance of the DEE method over centrifugation for a range of solutes. The method has been used to generate detailed interstitial water profiles of electron acceptor and contaminant concentrations along the flow path of a petroleum hydrocarbon plume in the U.K. Upper Chalk aquifer as part of a natural attenuation assessment.

  12. Fault rock texture and porosity type in Triassic dolostones

    NASA Astrophysics Data System (ADS)

    Agosta, Fabrizio; Grieco, Donato; Bardi, Alessandro; Prosser, Giacomo

    2015-04-01

    Preliminary results of an ongoing project aimed at deciphering the micromechanics and porosity evolution associated to brittle deformation of Triassic dolostones are presented. Samples collected from high-angle, oblique-slip, 10's to 100's m-throw normal faults crosscutting Mesozoic carbonates of the Neo Tethys (Campanian-Lucanian Platform) are investigated by mean of field geological mapping, optical microscopy, SEM and image analyses. The goal is to characterize in detail composition, texture and porosity of cataclastic rocks in order to assess the structural architecture of dolomitic fault cores. Moreover, the present study addresses the time-space control exerted by several micro-mechanisms such as intragranular extensional fracturing, chipping and shear fracturing, which took place during grain rolling and crushing within the evolving faults, on type, amount, dimensions and distribution of micropores present within the cataclastic fault cores. Study samples are representative of well-exposed dolomitic fault cores of oblique-slip normal faults trending either NW-SE or NE-SW. The high-angle normal faults crosscut the Mesozoic carbonates of the Campanian-Lucanian Platform, which overrode the Lagonegro succession by mean of low-angle thrust faults. Fault throws are measured by considering the displaced thrust faults as key markers after large scale field mapping (1:10,000 scale) of the study areas. In the field, hand samples were selected according to their distance from main slip surfaces and, in some case, along secondary slip surfaces. Microscopy analysis of about 100 oriented fault rock samples shows that, mostly, the study cataclastic rocks are made up of dolomite and sparse, minute survivor silicate grains deriving from the Lagonegro succession. In order to quantitatively assess the main textural classes, a great attention is paid to the grain-matrix ratio, grain sphericity, grain roundness, and grain sorting. By employing an automatic box-counting technique

  13. Influence of template fill in graphoepitaxy DSA

    NASA Astrophysics Data System (ADS)

    Doise, Jan; Bekaert, Joost; Chan, Boon Teik; Hong, SungEun; Lin, Guanyang; Gronheid, Roel

    2016-03-01

    Directed self-assembly (DSA) of block copolymers (BCP) is considered a promising patterning approach for the 7 nm node and beyond. Specifically, a grapho-epitaxy process using a cylindrical phase BCP may offer an efficient solution for patterning randomly distributed contact holes with sub-resolution pitches, such as found in via and cut mask levels. In any grapho-epitaxy process, the pattern density impacts the template fill (local BCP thickness inside the template) and may cause defects due to respectively over- or underfilling of the template. In order to tackle this issue thoroughly, the parameters that determine template fill and the influence of template fill on the resulting pattern should be investigated. In this work, using three process flow variations (with different template surface energy), template fill is experimentally characterized as a function of pattern density and film thickness. The impact of these parameters on template fill is highly dependent on the process flow, and thus pre-pattern surface energy. Template fill has a considerable effect on the pattern transfer of the DSA contact holes into the underlying layer. Higher fill levels give rise to smaller contact holes and worse critical dimension uniformity. These results are important towards DSA-aware design and show that fill is a crucial parameter in grapho-epitaxy DSA.

  14. Air cathode structure manufacture

    DOEpatents

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  15. Hydraulic and acoustic properties as a function of porosity in Fontainebleau Sandstone

    NASA Astrophysics Data System (ADS)

    Bourbie, Thierry; Zinszner, Bernard

    1985-11-01

    Laboratory measurements have been made of the permeability (k), free porosity (ϕL), compressional velocities (VP or VE), and compressional attenuations (QP or QE) in Fontainebleau sandstone over a continuous range of porosities ϕ from 3 to 28%. This large variation was achieved without any composition change: Fontainebleau sandstone is made of fine quartz grains with regular grain size (≈250 μm). Permeability was measured with a falling head permeameter. Velocities and attenuations were obtained either through an ultrasonic experiment for frequencies around 500 kHz or through a resonant bar technique experiment for frequencies around 5 kHz and in both cases with varying water saturation. The results show an excellent correlation between permeability k and total porosity ϕ for all our samples. For low porosities (ϕ = 3% to 9%), permeability (in millidarcies) is 2.75×10-5(ϕ)7.33, while for high porosities (ϕ = 9% to 28%), permeability k (in millidarcies) is given by 0.303(ϕ)3.05. The correlation is also excellent between free porosity and total porosity. On the other hand the correlation between acoustic properties and total porosity is not as clear as for hydraulic properties whatever the frequency (500 kHz or 5 kHz) or the water saturation. On the average, velocity decreases, and attenuation roughly increases with increasing total porosity. Velocity and attenuation values are related to the variation of grain contact structure, and two samples with the same porosity and permeability may exhibit different velocities and attenuations. The clear correlation between hydraulic properties and porosity is related to constant grain size, while the lack of correlation for acoustic properties emphasizes the importance of the microstructure.

  16. Air Research

    EPA Pesticide Factsheets

    EPA's air research provides the critical science to develop and implement outdoor air regulations under the Clean Air Act and puts new tools and information in the hands of air quality managers and regulators to protect the air we breathe.

  17. 30 CFR 817.72 - Disposal of excess spoil: Valley fill/head-of-hollow fills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... Uncontrolled surface drainage may not be directed over the outslope of the fill. (2) Runoff from areas above the fill and runoff from the surface of the fill shall be diverted into stabilized diversion channels designed to meet the requirements of § 817.43 and to safely pass the runoff from a 100-year,...

  18. 30 CFR 816.72 - Disposal of excess spoil: Valley fills/head-of-hollow fills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... Uncontrolled surface drainage may not be directed over the outslope of the fill. (2) Runoff from areas above the fill and runoff from the surface of the fill shall be diverted into stabilized diversion channels designed to meet the requirements of § 816.43 and, in addition, to safely pass the runoff from a...

  19. 30 CFR 816.72 - Disposal of excess spoil: Valley fills/head-of-hollow fills.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... such that the final slope after settlement will be toward properly designed drainage channels.... The maximum slope of the top of the fill shall be 33h:1v (3 percent). A drainage pocket may be.... Terraces on the fill shall be graded with a 3 to 5 percent grade toward the fill and a 1 percent...

  20. 30 CFR 817.72 - Disposal of excess spoil: Valley fill/head-of-hollow fills.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... such that the final slope after settlement will be toward properly designed drainage channels... slope of the top of the fill shall be 33h:lv (3 percent). A drainage pocket may be maintained at the... fill shall be graded with a 3 to 5 percent grade toward the fill and a 1 percent slope toward the...

  1. 30 CFR 817.72 - Disposal of excess spoil: Valley fill/head-of-hollow fills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... into the design and construction of the fill as follows: (1) The fill shall have, along the vertical... and from seeps and springs in the foundation of the disposal area. Rocks used in the rock core and... head of the fill during and after construction, to intercept surface runoff and discharge the...

  2. Using Grail Data to Assess the Effect of Porosity and Dilatancy on the Gravity Signature of Impact Craters on the Moon

    NASA Astrophysics Data System (ADS)

    Milbury, C.; Johnson, B. C.; Melosh, J., IV; Collins, G. S.; Blair, D. M.; Soderblom, J. M.; Zuber, M. T.

    2014-12-01

    NASA's dual Gravity Recovery and Interior Laboratory (GRAIL) spacecraft have globally mapped the lunar gravity field at unprecedented resolution; this has enabled the study of craters of all sizes and ages. Soderblom et al. [2014, LPSC abstract #1777] calculated the residual Bouguer anomalies for ~2700 craters 27-184 km in diameter (D). They found that the residual Bouguer anomaly over craters smaller than D~100 km is essentially 0±50 mGal, there is a transition for D~100-150 km, and craters larger than 184 km have a positive residual Bouguer anomaly that increases with increasing crater size. We use the iSALE shock physics hydrocode to model crater formation, including the effect of porosity and dilatancy (shear bulking). We use strength parameters of gabbroic anorthosite for the crust and dunite for the mantle. Our impactor sizes range from 6-30 km, which produce craters between 86-450 km in diameter for pre-impact target porosities of 0, 6.8, and 13.6%. We calculate the free-air and Bouguer gravity anomalies from our models and compare them to gravity data from GRAIL. We find that target porosity has the greatest effect on the gravity signature of lunar craters and can explain the observed ±50 mGal scatter in the residual Bouguer anomaly. We investigate variations of impact velocity, crustal thickness, and dilatancy angle; we find that these parameters do not affect the gravity as significantly as target porosity does. We find that the crater diameter at which mantle uplift dominates the crater gravity is dependent on target porosity, and that it occurs at a crater diameter that is close to the complex crater to peak-ring basin transition.

  3. Thermochemistry of zeolitic imidazolate frameworks of varying porosity.

    PubMed

    Hughes, James T; Bennett, Thomas D; Cheetham, Anthony K; Navrotsky, Alexandra

    2013-01-16

    The first thermochemical analysis by room-temperature aqueous solution calorimetry of a series of zeolite imidazolate frameworks (ZIFs) has been completed. The enthalpies of formation of the evacuated ZIFs-ZIF-zni, ZIF-1, ZIF-4, CoZIF-4, ZIF-7, and ZIF-8-along with as-synthesized ZIF-4 (ZIF-4·DMF) and ball-milling amorphized ZIF-4 (a(m)ZIF-4) were measured with respect to dense components: metal oxide (ZnO or CoO), the corresponding imidazole linker, and N,N dimethylformamide (DMF) in the case of ZIF-4·DMF. Enthalpies of formation of ZIFs from these components at 298 K are exothermic, but the ZIFs are metastable energetically with respect to hypothetical dense components in which zinc is bonded to nitrogen rather than oxygen. These enthalpic destabilizations increase with increasing porosity and span a narrow range from 13.0 to 27.1 kJ/mol, while the molar volumes extend from 135.9 to 248.8 cm(3)/mol; thus, almost doubling the molar volume results in only a modest energetic destabilization. The experimental results are supported by DFT calculations. The series of ZIFs studied tie in with previously studied MOF-5, creating a broader trend that mirrors a similar pattern by porous inorganic oxides, zeolites, zeotypes, and mesoporous silicas. These findings suggest that no immediate thermodynamic barrier precludes the further development of highly porous materials.

  4. Boiling radial flow in fractures of varying wall porosity

    SciTech Connect

    Barnitt, Robb Allan

    2000-06-01

    The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials. Nonporous and impermeable aluminum, highly porous and permeable Berea sandstone, and minimally porous and permeable graywacke from The Geysers geothermal field. On nonporous surfaces, the heat flux was not strongly coupled to injection rate into the fracture. However, for porous surfaces, heat flux, and associated values of excess temperature and a boiling convection coefficient exhibited variation with injection rate. Nucleation was shown to occur not upon the visible surface of porous materials, but a distance below the surface, within the matrix. The depth of boiling was a function of injection rate, thermal power supplied to the fracture, and the porosity and permeability of the rock. Although matrix boiling beyond fracture wall may apply only to a finite radius around the point of injection, higher values of heat flux and a boiling convection coefficient may be realized with boiling in a porous, rather than nonporous surface bounded fracture.

  5. Patterning of dispenser cathode surfaces to a controlled porosity

    NASA Technical Reports Server (NTRS)

    Garner, Charles E.; Deininger, William D.; Gibson, John; Thomas, Richard

    1989-01-01

    A process to pattern slots approximately 1.25 microns in width into 25-micron-thick W films that have been deposited onto flat or concave surfaces is discussed. A 25-micron-thick W film with a high degree of (100) orientation is chemically vapor deposited (CVD) onto a flat or concave Mo mandrel. A 5-micron-thick Al film is deposited onto the CVD W, followed by 2 microns of photoresist. On concave cathodes, XeCl2 laser ablation or X-ray lithography is used to pattern the photoresist, whereas on flat cathodes deep UV lithography can be used. The patterned photoresist serves as the mask in a Cl ion-beam-assisted etching (IBAE) process to pattern the Al. An alternative process is to deposit Al2O3 films onto the W and pattern the Al2O3 using laser ablation. The W film is then patterned to 3-6-micron slot widths using IBAE + ClF3 with the patterned Al or Al2O3 as the mask. Finally, a sputter deposition step is required to close up the slots to approximately 1 micron. The process described is capable of patterning concave dispenser cathodes to a controlled and precise porosity.

  6. Microbubble Fabrication of Concave-porosity PDMS Beads.

    PubMed

    Bertram, John R; Nee, Matthew J

    2015-12-15

    Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is particularly useful for separations applications. Porous polydimethylsiloxane (PDMS) beads can be produced by heat-curing such an emulsion, allowing the interface between the aqueous and aliphatic phases to mold the morphology of the polymer. In the procedures described here, both polymer and crosslinker (triethoxysilane) are sonicated together in a cold-bath sonicator. Following a period of cross-linking, emulsions are added dropwise to a hot surfactant solution, allowing the aqueous phase of the emulsion to separate, and forming porous polymer beads. We demonstrate that this method can be tuned, and the SAV ratio optimized, by adjusting the electrolyte content of the aqueous phase in the emulsion. Beads produced in this way are imaged with scanning electron microscopy, and representative SAV ratios are determined using Brunauer-Emmett-Teller (BET) analysis. Considerable variability with the electrolyte identity is observed, but the general trend is consistent: there is a maximum in SAV obtained at a specific concentration, after which porosity decreases markedly.

  7. Integrative Chemistry: Advanced functional cellular materials bearing multiscale porosity

    NASA Astrophysics Data System (ADS)

    Depardieu, M.; Kinadjian, N.; Backov, R.

    2015-07-01

    With this mini review we show through the sol-gel and emulsion-based Integrative Chemistry how it is possible to trigger materials dimensionality and beyond their functionalities when reaching enhanced applications. In here we focus on 3D macrocellular monolithic foams bearing hierarchical porosities and applications thereof. We first depict the general background of emulsions focusing on concentrated ones, acting as soft templates for the design of PolyHIPE foams, HIPE being the acronym of High Internal Phase Emulsions while encompassing both sol-gel and polymer chemistry. Secondly we extend this approach toward the design of hybrid organic-inorganic foams, labeled Organo-Si(HIPE), where photonics and heterogeneous catalysis applications are addressed. In a third section we show how inorganic Si(HIPE) matrices can be employed as sacrificial hard templates for the generation carbonaceous foams, labeled Carbon(HIPE). These foams being conductive we show applications when employed as electrodes for Li-S battery and as hosts for Li(BH4)-based hydrogen storage.

  8. Porosity controls in Late Jurassic algal reefs, Mississippi salt basin

    SciTech Connect

    Heydari, E.; Moore, C.H.

    1987-05-01

    Reefs associated with high-rise salt structures that were active during Late Jurassic deposition (Smackover-Haynesville) have been the target of numerous deep tests in the Mississippi Salt basin. One such test, in Wayne County, Mississippi, encountered a 24-m reef. The reef exhibited no porosity or permeability, while sequences above (21 m) and below (24 m) were dolomitized, porous, and permeable. The reef sequence consists of a facies mosaic of encrusting to columnar massive red coralline algae, laminated to stromatolitic blue-green algae(.) with associated pelleted internal sediments and other features characteristic of modern framework reefs. The reef complex exhibits a strong early marine diagenetic overprint consisting of bladed to fibrous magnesian calcite(.) cements and botryoidal masses of magnesian calcite or aragonite. The lack of discernible freshwater diagenesis and the nature of the reef framework seem to indicate deeper water conditions for reef development and subsequent early diagenesis. The associated dolomites have relict texture indicating that they were originally grainstones, perhaps derived from the reef itself. In the reef sequence, the geologic setting (relatively deep water), early marine cementation, and encrusting nature of the reef-formers produced a non-porous rock which was not susceptible to early dolomitization. However, the associated porous grainstones allowed active circulation of dolomitizing fluids (marine water.), leading to total dolomitization and a favorable reservoir facies.

  9. Droplet Measurement below Single-Layer Grid Fill

    NASA Astrophysics Data System (ADS)

    Vitkovic, Pavol

    2016-03-01

    The main part of the heat transfer in a cooling tower is in a fill zone. This one is consist of a cooling fill. For the cooling tower is used a film fill or grid fill or splash fill in the generally. The grid fill has lower heat transfer performance like film fill usually. But their advantage is high resistance to blockage of the fill. The grid fill is consisted with independent layers made from plastic usually. The layers consist of several bars connected to the different shapes. For experiment was used the rhombus shape. The drops diameter was measured above and below the Grid fill.

  10. ROLE OF POROSITY LOSS IN LIMITING SO2 CAPTURE BY CALCIUM BASED SORBENTS

    EPA Science Inventory

    The extent of high temperature (900-1,300°C), short time (<1 s) SO2 capture was found to be limited by temperature-dependent losses in the porosity of calcium based sorbents. At 970°C these porosity losses were caused by CO2-activated sintering. Sulfation of the sorbents either p...

  11. Hydrocarbon-water-rock interaction: Redox reaction as a mechanism for sandstone reservoir porosity enhancement

    SciTech Connect

    Shebl, M.A.; Surdam, R.C.

    1995-06-01

    Experiments evaluated the potential for and extent of oil-water-rock reactions in hydrocarbon reservoirs. Results indicate not only that significant potential exists for redox reactions between oxidized mineral phases and crude oil, but that such reactions can significantly alter porosity and permeability characteristics of an elastic hydrocarbon reservoir. The red (oxidized) sandstones used in the redox experiment initially contained 10 to 25% carbonate, anhydrite, and intergranular clay cements. Porosity ranged from 6 to 15%. The sandstones were gray or white after experimentation, and porosity increased 12 to 20% over original values, primarily due to carbonate dissolution. It is suggested that during the redox experiments, the iron oxides ({+-} sulphate) were reduced and hydrocarbon was oxidized to produce oxygenated organic compounds (e.g., organic acid anions, CO{sub 2}). These redox reaction products destabilized the carbonate cements and enhanced sandstone porosity. It is concluded that redox reactions involving crude oil and the mineral matrix of these reservoir rocks in the presence of H{sub 2}O do occur and may result in significantly enhanced porosity. Hydrocarbon emplacement and the resultant redox reactions can cause bleaching and changes in porosity and permeability. This relationship is well documented in the Wingate, White Rim, and Tensleep sandstones. The hydrocarbon reservoir units are white to gray and have good porosity and permeability. The adjacent non-reservoir units are red (due to hematite staining), and have good carbonate cementation and poor porosity and permeability, confining hydrocarbon flow to the nearby reservoir units or associated fractures.

  12. Dual-porosity Mn2O3 cubes for highly efficient dye adsorption.

    PubMed

    Shao, Yongjiu; Ren, Bin; Jiang, Hanmei; Zhou, Bingjie; Lv, Liping; Ren, Jingzheng; Dong, Lichun; Li, Jing; Liu, Zhenfa

    2017-03-08

    Dual-porosity materials containing both macropores and mesopores are highly desired in many fields. In this work, we prepared dual-porosity Mn2O3 cube materials with large-pore mesopores, in which, macropores are made by using carbon spheres as the hard templates, while the mesopores are produced via a template-free route. The attained dual-porosity Mn2O3 materials have 24nm of large-pore mesopores and 700nm of macropores. Besides, the achieved materials own cubic morphologies with particle sizes as large as 6.0μm, making them separable in the solution by a facile natural sedimentation. Dye adsorption measurements reveal that the dual-porosity materials possess a very high maximum adsorption capacity of 125.6mg/g, much larger than many reported materials. Particularly, the adsorbents can be recycled and the dye removal efficiency can be well maintained at 98% after four cycles. Adsorption isotherm and kinetics show that the Langmuir model and the pseudo-second-order kinetics model can well describe the adsorption process of Congo Red on the dual-porosity Mn2O3 cube materials. In brief, the reported dual-porosity Mn2O3 demonstrates a good example for controlled preparation of dual-porosity materials with large-pore mesopores, and the macropore-mesopore dual-porosity distribution is good for mass transfer in dye adsorption application.

  13. Geometry Properties of Porosity Waves during Magma Migration: The Influence of Viscosities and Damage

    NASA Astrophysics Data System (ADS)

    Cai, Z.; Bercovici, D.

    2014-12-01

    Partial melting occurs along grain boundaries and migrates through porous flow, leading to magma segregation in the mantle. Solitary porosity waves created by a perturbation in melting have been studied in the flow of a low viscosity fluid in a deformable matrix (McKenzie 1984, Scott and Stevenson 1986, Barcilon and Richter 1986, Spiegelman 1993, Wiggins and Spiegelman 1995). However, in a fairly complicated multi-physics, multi-scale process of magma migration, the geometry and instability of porosity waves can be affected by both mechanical and thermal factors, leaving different propagation signatures. In this work we develop a two-dimensional, two-phase damage model of magma-fracturing, and study the influence of viscosities and damage (void generation and microcracking) on the geometry properties of porosity waves. We first benchmark our solitary solutions with previous works and solve 2-D finite-amplitude waves numerically using spectral and semi-spectral method. We show that damage, decompaction weakening of the matrix and porosity-driven viscosities can alter the geometry of stable porosity waves, and result in an elongated or flattened wave front with a trail of smaller porosity. Such trails may localize subsequent waves and form porosity passage in the matrix. Scaling analysis of the time-dependent porosity waves are conducted and amount of magma reaching to the top of the melting region are estimated. Future work will include evaluating the thermal and seismic signatures during and after melt migration in two-phase porous flow.

  14. Secondary porosity in immature Late Cretaceous and Tertiary sandstones, northeast Alaska and northwest Canada

    SciTech Connect

    Myers, M.D. ); Smith, T.N. )

    1990-05-01

    Petrographic and scanning electron microscope analysis of Upper Cretaceous to lower Eocene sandstone from outcrops west of the Mackenzie delta and in the central Arctic National Wildlife Refuge (ANWR) reveals secondary porosity. Recognizing this secondary porosity is important for oil and gas exploration because early diagenesis has eliminated most primary porosity in these immature litharenites. The litharenites are dominated by grains of quartz, cherty argillite, chert, volcanic rock fragments, variable amounts of feldspar, and minor amounts of metamorphic rock fragments. Because of the abundance of ductile grains all deep burial (probable burial to depths in excess of 3,000 m), these sandstones have suffered the loss of most primary porosity. Additional reduction of primary porosity has occurred due to the formation of minor amount of precompaction rim cement (carbonate, chlorite, and illite/smectite) and syncompaction quartz overgrowths. Dissolution of framework grains and, to a lesser degree, matrix has resulted in secondary porosities of up to 8% in outcrop samples. Framework grains commonly dissolved include volcanic rock fragments, feldspar, chert, cherty argillite, argillite, and quartz. Two processes are responsible for the dissolution. The first process is the direct dissolution of grains. The second process involves two steps in which grains and matrix are initially replaced by carbonate cement followed by dissolution of the cement and creation of secondary porosity. Secondary porosity is reported to exceed 20% in subsurface samples in northwest Canada.

  15. Tuning the spectral emittance of α-SiC open-cell foams up to 1300 K with their macro porosity

    NASA Astrophysics Data System (ADS)

    Rousseau, B.; Guevelou, S.; Mekeze-Monthe, A.; Vicente, J.; Del Campo, L.; De Sousa Meneses, D.; Echegut, P.; Caliot, C.; Flamant, G.

    2016-06-01

    A simple and robust analytical model is used to finely predict the spectral emittance under air up to 1300 K of α-SiC open-cell foams constituted of optically thick struts. The model integrates both the chemical composition and the macro-porosity and is valid only if foams have volumes higher than their Representative Elementary Volumes required for determining their emittance. Infrared emission spectroscopy carried out on a doped silicon carbide single crystal associated to homemade numerical tools based on 3D meshed images (Monte Carlo Ray Tracing code, foam generator) make possible to understand the exact role of the cell network in emittance. Finally, one can tune the spectral emittance of α-SiC foams up to 1300 K by simply changing their porosity.

  16. Nematic wetting and filling of crenellated surfaces

    NASA Astrophysics Data System (ADS)

    Silvestre, N. M.; Eskandari, Z.; Patrício, P.; Romero-Enrique, J. M.; Telo da Gama, M. M.

    2012-07-01

    We investigate nematic wetting and filling transitions of crenellated surfaces (rectangular gratings) by numerical minimization of the Landau-de Gennes free energy as a function of the anchoring strength, for a wide range of the surface geometrical parameters: depth, width, and separation of the crenels. We have found a rich phase behavior that depends in detail on the combination of the surface parameters. By comparison to simple fluids, which undergo a continuous filling or unbending transition, where the surface changes from a dry to a filled state, followed by a wetting or unbinding transition, where the thickness of the adsorbed fluid becomes macroscopic and the interface unbinds from the surface, nematics at crenellated surfaces reveal an intriguingly rich behavior: in shallow crenels only wetting is observed, while in deep crenels, only filling transitions occur; for intermediate surface geometrical parameters, a new class of filled states is found, characterized by bent isotropic-nematic interfaces, which persist for surfaces structured on large scales, compared to the nematic correlation length. The global phase diagram displays two wet and four filled states, all separated by first-order transitions. For crenels in the intermediate regime re-entrant filling transitions driven by the anchoring strength are observed.

  17. A modeling and numerical algorithm for thermoporomechanics in multiple porosity media for naturally fractured reservoirs

    NASA Astrophysics Data System (ADS)

    Kim, J.; Sonnenthal, E. L.; Rutqvist, J.

    2011-12-01

    Rigorous modeling of coupling between fluid, heat, and geomechanics (thermo-poro-mechanics), in fractured porous media is one of the important and difficult topics in geothermal reservoir simulation, because the physics are highly nonlinear and strongly coupled. Coupled fluid/heat flow and geomechanics are investigated using the multiple interacting continua (MINC) method as applied to naturally fractured media. In this study, we generalize constitutive relations for the isothermal elastic dual porosity model proposed by Berryman (2002) to those for the non-isothermal elastic/elastoplastic multiple porosity model, and derive the coupling coefficients of coupled fluid/heat flow and geomechanics and constraints of the coefficients. When the off-diagonal terms of the total compressibility matrix for the flow problem are zero, the upscaled drained bulk modulus for geomechanics becomes the harmonic average of drained bulk moduli of the multiple continua. In this case, the drained elastic/elastoplastic moduli for mechanics are determined by a combination of the drained moduli and volume fractions in multiple porosity materials. We also determine a relation between local strains of all multiple porosity materials in a gridblock and the global strain of the gridblock, from which we can track local and global elastic/plastic variables. For elastoplasticity, the return mapping is performed for all multiple porosity materials in the gridblock. For numerical implementation, we employ and extend the fixed-stress sequential method of the single porosity model to coupled fluid/heat flow and geomechanics in multiple porosity systems, because it provides numerical stability and high accuracy. This sequential scheme can be easily implemented by using a porosity function and its corresponding porosity correction, making use of the existing robust flow and geomechanics simulators. We implemented the proposed modeling and numerical algorithm to the reaction transport simulator

  18. A review of recent advances in the assessment of bone porosity, permeability, and interstitial fluid flow

    PubMed Central

    Cardoso, Luis; Fritton, Susannah P.; Gailani, Gaffar; Benalla, Mohammed; Cowin, Stephen C.

    2012-01-01

    This contribution reviews recent research performed to assess the porosity and permeability of bone tissue with the objective of understanding interstitial fluid movement. Bone tissue mechanotransduction is considered to occur due to the passage of interstitial pore fluid adjacent to dendritic cell structures in the lacunar-canalicular porosity. The movement of interstitial fluid is also necessary for the nutrition of osteocytes. This review will focus on four topics related to improved assessment of bone interstitial fluid flow. First, the advantages and limitations of imaging technologies to visualize bone porosities and architecture at several length scales are summarized. Second, recent efforts to measure the vascular porosity and lacunar-canalicular microarchitecture are discussed. Third, studies associated with the measurement and estimation of the fluid pressure and permeability in the vascular and lacunar-canalicular domains are summarized. Fourth, the development of recent models to represent the interchange of fluids between the bone porosities is described. PMID:23174418

  19. Evaluation of Oven-Cured Solid Carbon/epoxy Composites with Various Porosity Levels

    NASA Astrophysics Data System (ADS)

    Stone, M. A.

    2009-03-01

    Cirrus has developed a strong core competency fabricating composite components using oven cure vacuum bag technology. When using this process, porosity levels must be carefully managed and effects of porosity well understood. Excessive porosity negatively affects material performance and reduces the effectiveness of the ultrasonic NDI method. This paper will present material characterization results from carbon/epoxy composite panels produced with various levels of porosity. Panels were inspected using two different ultrasonic methods. Panels were destructively tested to correlate static mechanical and physical properties to ultrasonic absorption coefficients. The goal of this work is to characterize material behavior to allow ultrasonic inspection in a manufacturing environment on vacuum bag oven-cured parts where porosity may be a factor.

  20. Post-flight Analysis of the Argon Filled Ion Chamber

    NASA Technical Reports Server (NTRS)

    Tai, H.; Goldhagen, P.; Jones, I. W.; Wilson, J. W.; Maiden, D. L.; Shinn, J. L.

    2003-01-01

    Atmospheric ionizing radiation is a complex mixture of primary galactic and solar cosmic rays and a multitude of secondary particles produced in collision with air nuclei. The first series of Atmospheric Ionizing Radiation (AIR) measurement flights on the NASA research aircraft ER-2 took place in June 1997. The ER-2 flight package consisted of fifteen instruments from six countries and were chosen to provide varying sensitivity to specific components. These AIR ER-2 flight measurements are to characterize the AIR environment during solar minimum to allow the continued development of environmental models of this complex mixture of ionizing radiation. This will enable scientists to study the ionizing radiation health hazard associated with the high-altitude operation of a commercial supersonic transport and to allow estimates of single event upsets for advanced avionics systems design. The argon filled ion chamber representing about 40 percent of the contributions to radiation risks are analyzed herein and model discrepancies for solar minimum environment are on the order of 5 percent and less. Other biologically significant components remain to be analyzed.

  1. [Amalgam fillings and T-lymphocyte changes].

    PubMed

    Giuliani, M; Rumi, C; Marciani, F; Boari, A; Rumi, G; Di Felice, R

    1990-07-01

    Dental amalgam and nickel alloys have been considered quite safe. Previous authors reported the effect of dental amalgam and nickel alloys on human T-lymphocytes modifications after amalgam dental fillings, into dose-dependence of any modifications and into possible temporary. Eight patients were subjected to dental care with amalgam dental fillings. Drawings of blood were executed at start, fifteen days after late fillings and two months later. The results about modifications of T-lymphocytes were not univocal. We believe, at now, that temporary modifications of the immunity seem to be related to a cytotoxic mechanism.

  2. Evolution of porosity and diffusivity associated with chemical weathering of a basalt clast

    SciTech Connect

    Navarre-Sitchler, A.; Steefel, C.I.; Yang, L.; Tomutsa, L.; Brantley, S.L.

    2009-02-15

    Weathering of rocks as a result of exposure to water and the atmosphere can cause significant changes in their chemistry and porosity. In low-porosity rocks, such as basalts, changes in porosity, resulting from chemical weathering, are likely to modify the rock's effective diffusivity and permeability, affecting the rate of solute transport and thus potentially the rate of overall weathering to the extent that transport is the rate limiting step. Changes in total porosity as a result of mineral dissolution and precipitation have typically been used to calculate effective diffusion coefficients through Archie's law for reactive transport simulations of chemical weathering, but this approach fails to account for unconnected porosity that does not contribute to transport. In this study, we combine synchrotron X-ray microcomputed tomography ({mu}CT) and laboratory and numerical diffusion experiments to examine changes in both total and effective porosity and effective diffusion coefficients across a weathering interface in a weathered basalt clast from Costa Rica. The {mu}CT data indicate that below a critical value of {approx}9%, the porosity is largely unconnected in the basalt clast. The {mu}CT data were further used to construct a numerical pore network model to determine upscaled, effective diffusivities as a function of total porosity (ranging from 3 to 30%) for comparison with diffusivities determined in laboratory tracer experiments. By using effective porosity as the scaling parameter and accounting for critical porosity, a model is developed that accurately predicts continuum-scale effective diffusivities across the weathering interface of the basalt clast.

  3. Laboratory measurements of Vp and Vs in a porosity-developed crustal rock: Experimental investigation into the effects of porosity at deep crustal pressures

    NASA Astrophysics Data System (ADS)

    Saito, Satoshi; Ishikawa, Masahiro; Arima, Makoto; Tatsumi, Yoshiyuki

    2016-05-01

    In order to evaluate the influence of porosity on the elastic properties of crustal rocks at deep crustal pressures, we performed laboratory measurements of compressional-wave (Vp) and shear-wave (Vs) velocities in a porosity-developed gabbro sample up to 1.0 GPa at room temperature. Based on the measured Vp and Vs data, we evaluated the changes in velocities, Vp/Vs, Poisson's ratio (σ), and total porosity of the rock as a function of pressure. Compared with the 'porosity-free' intrinsic elastic values of the gabbro sample, our results suggest that the development of porosity in crustal rocks lowers their Vp, Vs, Vp/Vs, and Poisson's ratio. Deviations (ΔVp, ΔVs, ΔVp/Vs, and Δσ) of the measured values from the intrinsic values are enhanced with increasing porosity. We evaluated the ΔVp from previous experimental study on the rocks of Tanzawa plutonic complex providing constraints on interpretation of the seismic velocity profiles of the Izu-Bonin-Mariana (IBM) arc and found a large negative ΔVp (up to - 22.7%) at lower pressures. The intrinsic velocity combined with the measured velocity data at in situ pressure conditions suggest that the ranges of Vp (6.0-6.5 km/s) in the middle crust of the IBM arc reflect the presence of considerable porosity and its closure in intermediate rocks and/or the change of composition from felsic to intermediate in mid-crustal rocks.

  4. REMEDIATION OF TCE-CONTAMINATED GROUNDWATER BY A PERMEABLE REACTIVE BARRIER FILLED WITH PLANT MULCH (BIOWALL)

    EPA Science Inventory

    A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base (in Oklahoma, USA) to treat trichloroethylene (TCE) contamination in ground water emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 ...

  5. MTR, TRA603. SUBPILE ROOM PLAN AND SECTIONS. CONCRETE FILL AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MTR, TRA-603. SUB-PILE ROOM PLAN AND SECTIONS. CONCRETE FILL AT TWO ELEVATIONS. EXIT AIR DUCT. EXIT AND INLET WATER. PEBBLE CUBICLE AND BIN. BLAW-KNOX 3150-803-45, 9/1950. INL INDEX NO. 531-0603-62-098-100601, REV. 1. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  6. Median-porosity contour maps of the J Sandstone, Dakota Group, in the Denver Basin, Colorado, Nebraska, and Wyoming

    USGS Publications Warehouse

    Higley, D.K.; Gautier, D.L.

    1987-01-01

    Porosity data compiled in this study were determined from J sandstone cores from 134 widely spaced boreholes. Porosity in areas of poor core coverage was determined from neutron density logs from an additional 20 boreholes ( corrected to core average grain density). Median, rather than average, porosity was used in order to minimize the statistical effect of anomalously high and low porosity values. Thirty-five oil companies and independent operators supplied core porosity data. Core porosities were determined by means of helium porosimetry, primarily by Core Laboratories of Denver, Colo.

  7. Soil porosity correlation and its influence in percolation dynamics

    NASA Astrophysics Data System (ADS)

    Rodriguez, Alfredo; Capa-Morocho, Mirian; Ruis-Ramos, Margarita; Tarquis, Ana M.

    2016-04-01

    The prediction of percolation in natural soils is relevant for modeling root growth and optimizing infiltration of water and nutrients. Also, it would improve our understanding on how pollutants as pesticides, and virus and bacteria (Darnault et al., 2003) reach significant depths without being filtered out by the soil matrix (Beven and Germann, 2013). Random walk algorithms have been used successfully to date to characterize the dynamical characteristics of disordered media. This approach has been used here to describe how soil at different bulk densities and with different threshold values applied to the 3D gray images influences the structure of the pore network and their implications on particle flow and distribution (Ruiz-Ramos et al., 2009). In order to do so first we applied several threshold values to each image analyzed and characterized them through Hurst exponents, then we computed random walks algorithms to calculate distances reached by the particles and speed of those particles. At the same time, 3D structures with a Hurst exponent of ca 0.5 and with different porosities were constructed and the same random walks simulations were replicated over these generated structures. We have found a relationship between Hurst exponents and the speed distribution of the particles reaching percolation of the total soil depth. REFERENCES Darnault, C.J. G., P. Garnier, Y.J. Kim, K.L. Oveson, T.S. Steenhuis, J.Y. Parlange, M. Jenkins, W.C. Ghiorse, and P. Baveye (2003), Preferential transport of Cryptosporidium parvum oocysts in variably saturated subsurface environments, Water Environ. Res., 75, 113-120. Beven, Keith and Germann, Peter. 2013. Macropores and water flow in soils revisited. Water Resources Research, 49(6), 3071-3092. DOI: 10.1002/wrcr.20156. Ruiz-Ramos, M., D. del Valle, D. Grinev, and A.M. Tarquis. 2009. Soil hydraulic behaviour at different bulk densities. Geophysical Research Abstracts, 11, EGU2009-6234.

  8. Visualizing bone porosities using a tabletop scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, D.; DaPonte, J.; Broadbridge, C. C.; Daniel, D.; Alter, L.

    2010-04-01

    Pores are naturally occurring entities in bone. Changes in pore size and number are often associated with diseases such as Osteoporosis and even microgravity during spaceflight. Studying bone perforations may yield great insight into bone's material properties, including bone density and may contribute to identifying therapies to halt or potentially reverse bone loss. Current technologies used in this field include nuclear magnetic resonance, micro-computed tomography and the field emission scanning electron microscope (FE-SEM) 2, 5. However, limitations in each method limit further advancement. The objective of this study was to assess the effectiveness of using a new generation of analytical instruments, the TM-1000 tabletop, SEM with back-scatter electron (BSE) detector, to analyze cortical bone porosities. Hind limb unloaded and age-based controlled mouse femurs were extracted and tested in vitro for changes in pores on the periosteal surface. An important advantage of using the tabletop is the simplified sample preparation that excludes extra coatings, dehydration and fixation steps that are otherwise required for conventional SEM. For quantitative data, pores were treated as particles in order to use an analyze particles feature in the NIH ImageJ software. Several image-processing techniques for background smoothing, thresholding and filtering were employed to produce a binary image suitable for particle analysis. It was hypothesized that the unloaded bones would show an increase in pore area, as the lack of mechanical loading would affect bone-remodeling processes taking place in and around pores. Preliminary results suggest only a slight different in frequency but not in size of pores between unloaded and control femurs.

  9. Diagenesis and porosity evolution, Norphlet Formation in Mobile Bay, Alabama

    SciTech Connect

    Lock, B.E.; Broussard, S.W.

    1988-02-01

    Major deposits of natural gas were discovered in the Norphlet Formation beneath Mobile Bay in 1979. The reservoirs are in arkosic sandstones at depths greater than 20,000 ft, yet the productive interval has porosities up to 25%. Overlying the porous zone is a tight cap of thoroughly cemented sandstone of variable thickness, which poses problems for exploration and production. The tight zone, which together with overlying basal Smackover forms the reservoir seal, may be so thick that the underlying productive interval is substantially reduced. The upper parts of the Norphlet, in common with many other eolian sands, were reworked during a subsequent transgression. There is not a full correspondence, however, between the tight rock and the reworked facies. The origin of the impermeable zone is better understood as a function of the diagenetic history only partially related to depositional facies. It is proposed that, at an early stage of diagenesis, brines derived from the underlying Louann Salt and Werner Formation deposited anhydrite and possibly halite cements in the lower part of the Norphlet Formation. Marine working of the upper sands may have helped to disperse these brines from the upper part of the Norphlet, and the depth of reworking may even have been partially influenced by incipient cementation. The zones not already cemented by evaporites were subsequently cemented by quartz and feldspar overgrowths. At a very late stage, deep in the subsurface, the evaporite cements were flushed from the lower parts of the Norphlet, and locally abundant small feldspar crystals randomly nucleated in the pores. Gas migrated into the formation shortly afterward. Evaporites may play another important role in the petroleum geology of the deep Norphlet: the source of the gas may have been the underlying evaporites.

  10. Kinetic controls on early karst aquifer porosity development

    SciTech Connect

    Groves, C.G. ); Howard, A.D. . Dept. of Environmental Sciences)

    1992-01-01

    A series of simulations using the newly developed model KARST has been performed to investigate limiting kinetic controls on limestone dissolution during the earliest stages of karst aquifer porosity development. This FORTRAN model couples fluid flow within and dissolution of circular cross section conduits, and considers surface reaction rates (both far from and close to thermodynamic equilibrium), mass transfer rates of reaction products to the bulk fluid, and rates of homogeneous reactions associated with dissolution of CO[sub 2] gas in water. Mass transfer theory for both laminar and turbulent flow cases is included. Runs were made with a wide variety of initial conditions of passage geometry, head gradient, and initial PCO[sub 2]. Results show a consistent pattern of kinetic control that varies as functions of time as well as position along the conduit. Slow, higher order surface reaction rates (close to equilibrium), diffusion rates, and rapid, lower order reaction rates (far from equilibrium) are found to be limiting steps at various times and location. Under no conditions in the simulations did the rate of CO[sub 2] hydration limit dissolution. Thresholds between the various kinetic regimes were found to be associated with a critical distance from equilibrium, as well as the transition from laminar to turbulent flow. As a result of interactions between flow and chemical conditions, passage growth (measure by fluid discharge rates) can be divided into an initial, slow period initiation and a more rapid one (enlargement). The onset of the enlargement phase was not found to coincide with any single kinetic event.

  11. Microleakage of root-end filling materials.

    PubMed

    Fogel, H M; Peikoff, M D

    2001-07-01

    The purpose of this study was to evaluate the microleakage of various root-end filling materials using a fluid filtration system. Sixty extracted human single-rooted teeth were used. The crowns were removed, the canals prepared, and root-end fillings placed. The samples were divided into two control and five experimental groups. The root-end filling materials tested were: amalgam, Intermediate Restorative Material (IRM), a dentin-bonded resin, Super-EBA, and mineral trioxide aggregate. The results showed that amalgam root-end fillings demonstrated significantly more microleakage than Super-EBA, dentin-bonded resin, or mineral trioxide aggregate. There was no significant difference between amalgam and IRM. However IRM was also not significantly different from the other three groups. There were no significant differences between the other three groups.

  12. 5 CFR 362.303 - Filling positions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... possesses a Ph.D. or equivalent degree directly related to the STEM position the agency is seeking to fill... candidate possesses a Ph.D. or equivalent degree directly related to the position the agency is seeking...

  13. 5 CFR 362.303 - Filling positions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... possesses a Ph.D. or equivalent degree directly related to the STEM position the agency is seeking to fill... candidate possesses a Ph.D. or equivalent degree directly related to the position the agency is seeking...

  14. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    EPA Science Inventory

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  15. Drop Weight Impact Behavior of Al-Si-Cu Alloy Foam-Filled Thin-Walled Steel Pipe Fabricated by Friction Stir Back Extrusion

    NASA Astrophysics Data System (ADS)

    Hangai, Yoshihiko; Nakano, Yukiko; Utsunomiya, Takao; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

    2017-02-01

    In this study, Al-Si-Cu alloy ADC12 foam-filled thin-walled stainless steel pipes, which exhibit metal bonding between the ADC12 foam and steel pipe, were fabricated by friction stir back extrusion. Drop weight impact tests were conducted to investigate the deformation behavior and mechanical properties of the foam-filled pipes during dynamic compression tests, which were compared with the results of static compression tests. From x-ray computed tomography observation, it was confirmed that the fabricated foam-filled pipes had almost uniform porosity and pore size distributions. It was found that no scattering of the fragments of collapsed ADC12 foam occurred for the foam-filled pipes owing to the existence of the pipe surrounding the ADC12 foam. Preventing the scattering of the ADC12 foam decreases the drop in stress during dynamic compression tests and therefore improves the energy absorption properties of the foam.

  16. Capillarity in metal casting mold filling

    NASA Astrophysics Data System (ADS)

    Hilden, Jon L.

    In metal casting processes, surface tension of the molten metal typically resists filling of the metal into the mold. The effects are greater for smaller mold cavities, and ultimately, the smallest cavities may not be filled. Surface tension forces can be overcome by applying pressure (head) to the molten metal, thus forcing metal into the cavities. However, a pressure-window will exist, too little pressure resulting in non-filled cavities and too much pressure resulting in penetration of the mold, which is itself porous. Filling-pressure windows are investigated for cylindrical-shaped mold cavities on both a theoretical and experimental basis. The lower bound of the filling pressure window is examined by treating cylindrical mold cavities as cylinders lined with packed spheres representing mold particles. The upper bound is examined by treating the mold as a 3-D array of close-packed spheres. The experimental work concerns industrial-scale vacuum investment casting of superalloy IN718 into molds containing various cylindrical mold cavities at various heights (heads). The experimental results are found to be in good agreement with the numerical modeling predictions for filling of rough (sphere-lined) cylindrical mold cavities.

  17. Examining the influence of heterogeneous porosity fields on conservative solute transport

    USGS Publications Warehouse

    Hu, B.X.; Meerschaert, M.M.; Barrash, W.; Hyndman, D.W.; He, C.; Li, X.; Guo, Laodong

    2009-01-01

    It is widely recognized that groundwater flow and solute transport in natural media are largely controlled by heterogeneities. In the last three decades, many studies have examined the effects of heterogeneous hydraulic conductivity fields on flow and transport processes, but there has been much less attention to the influence of heterogeneous porosity fields. In this study, we use porosity and particle size measurements from boreholes at the Boise Hydrogeophysical Research Site (BHRS) to evaluate the importance of characterizing the spatial structure of porosity and grain size data for solute transport modeling. Then we develop synthetic hydraulic conductivity fields based on relatively simple measurements of porosity from borehole logs and grain size distributions from core samples to examine and compare the characteristics of tracer transport through these fields with and without inclusion of porosity heterogeneity. In particular, we develop horizontal 2D realizations based on data from one of the less heterogeneous units at the BHRS to examine effects where spatial variations in hydraulic parameters are not large. The results indicate that the distributions of porosity and the derived hydraulic conductivity in the study unit resemble fractal normal and lognormal fields respectively. We numerically simulate solute transport in stochastic fields and find that spatial variations in porosity have significant effects on the spread of an injected tracer plume including a significant delay in simulated tracer concentration histories.

  18. Effect of porosities of bilayered porous scaffolds on spontaneous osteochondral repair in cartilage tissue engineering

    PubMed Central

    Dong, Jian; Ding, Jiandong

    2015-01-01

    Poly(lactide-co-glycolide)-bilayered scaffolds with the same porosity or different ones on the two layers were fabricated, and the porosity effect on in vivo repairing of the osteochondral defect was examined in a comparative way for the first time. The constructs of scaffolds and bone marrow-derived mesenchymal stem cells were implanted into pre-created osteochondral defects in the femoral condyle of New Zealand white rabbits. After 12 weeks, all experimental groups exhibited good cartilage repairing according to macroscopic appearance, cross-section view, haematoxylin and eosin staining, toluidine blue staining, immunohistochemical staining and real-time polymerase chain reaction of characteristic genes. The group of 92% porosity in the cartilage layer and 77% porosity in the bone layer resulted in the best efficacy, which was understood by more biomechanical mimicking of the natural cartilage and subchondral bone. This study illustrates unambiguously that cartilage tissue engineering allows for a wide range of scaffold porosity, yet some porosity group is optimal. It is also revealed that the biomechanical matching with the natural composite tissue should be taken into consideration in the design of practical biomaterials, which is especially important for porosities of a multi-compartment scaffold concerning connected tissues. PMID:26813511

  19. Regional diagenetic variation in Norphlet sandstone: Implications for reservoir quality and the origin of porosity

    SciTech Connect

    Kugler, R.L.; McHugh, A. )

    1990-09-01

    Although deeply buried (18,000->20,000 ft) eolian and reworked marine Norphlet arkose and subarkose in Mississippi, Alabama, and Florida have been intensely studied by several workers, fundamental questions remain regarding diagenetic controls on reservoir quality and the origin of porosity. In spite of a regionally uniform framework composition of quartz, albite, and potassium feldspar, the diagenetic character of the unit is variable on a scale ranging from individual laminations to single hydrocarbon-producing fields to areas encompassing several fields or offshore blocks. The presence or absence of clay minerals in various forms clearly is a dominant control on porosity-permeability trends. In deep reservoirs in Mobile Bay and offshore Alabama and Florida, petrographic evidence for dissolution of pervasive authigenic carbonate and/or evaporite minerals to produce high secondary porosity values is equivocal or absent. Although evidence exists for some secondary porosity, much porosity appears to be relict primary porosity. On a regional scale, including both onshore and offshore areas, sandstones with radial, authigenic chlorite coats consistently have high porosity and permeability. In Mobile Bay and offshore Alabama, the distribution of this form of chlorite may be controlled by the presence of precursor clay/iron-oxide grain coats. The occurrence of these coats likely is related to environment of deposition.

  20. Neutron radiography and tomography investigations on the porosity of the as-cast titanium femoral stem

    NASA Astrophysics Data System (ADS)

    Sutiyoko; Suyitno; Mahardika, M.; Akbar, F.; Juliani; Setiawan; Baroto

    2017-02-01

    Gating system design in the centrifugal casting is one of the factors that influence the porosity of the femoral stem. The objective of this research is to analysis the porosity in the as-cast titanium femoral stem by neutron radiography and tomography. Three gating system designs which in three-ingates, four-ingates, and four-ingates by inversed position of the femoral stem were casted by a vertical centrifugal casting in investment mold. The porosity distribution in the titanium femoral stem was investigated by the neutron radiography film and followed by neutron tomography. The results indicate that there are large internal porosity in the subsurface region on both of the four-ingates designs but only small internal porosity on the three-ingates design. The large porosity also takes place in largest part of the femoral stem at all of the gating system designs. The product may be rejected due to the sub-surface porosity. The three-ingates design has the smallest risk on the reject product.

  1. Quantification of Organic Porosity and Water Accessibility in Marcellus Shale Using Neutron Scattering

    SciTech Connect

    Gu, Xin; Mildner, David F. R.; Cole, David R.; Rother, Gernot; Slingerland, Rudy; Brantley, Susan L.

    2016-04-28

    Pores within organic matter (OM) are a significant contributor to the total pore system in gas shales. These pores contribute most of the storage capacity in gas shales. Here we present a novel approach to characterize the OM pore structure (including the porosity, specific surface area, pore size distribution, and water accessibility) in Marcellus shale. By using ultrasmall and small-angle neutron scattering, and by exploiting the contrast matching of the shale matrix with suitable mixtures of deuterated and protonated water, both total and water-accessible porosity were measured on centimeter-sized samples from two boreholes from the nanometer to micrometer scale with good statistical coverage. Samples were also measured after combustion at 450 °C. Analysis of scattering data from these procedures allowed quantification of OM porosity and water accessibility. OM hosts 24–47% of the total porosity for both organic-rich and -poor samples. This porosity occupies as much as 29% of the OM volume. In contrast to the current paradigm in the literature that OM porosity is organophilic and therefore not likely to contain water, our results demonstrate that OM pores with widths >20 nm exhibit the characteristics of water accessibility. In conclusion, our approach reveals the complex structure and wetting behavior of the OM porosity at scales that are hard to interrogate using other techniques.

  2. Geochemical tracers of dolomitizing fluids: A tool for predicting diagenetically controlled porosity on a reservoir scale

    SciTech Connect

    Major, R.P.; Lucia, F.J.; Ruppel, S.C. )

    1992-04-01

    Mole-per-mole replacement of calcite by dolomite yields an approximately 12% increase in porosity because dolomite is denser than calcite. However, data from the Pliocene-Pleistocene Seroe Domi Formation of Bonaire, Netherlands Antilles, demonstrate the dolomitization of these rocks resulted in porosity reduction. Rocks proximal to the source of dolomitizing fluids exhibit a greater amount of porosity occlusion than more distal rocks, indicating that dolomitization is a porosity-destroying process and that the degree of destruction can be calibrated to the flow path of dolomitizing fludis. Porosity observed in Bonaire dolomite varies over a distance of hundreds of meters along fluid-flow paths. In three examples of dolomites in which the pathways of dolomitizing fluids can be interpreted from the spatial geometry of dolomite compositions, the distances over which these changes occur are pertinent to interpreting diagenetically controlled reservoir heterogeneity in oil and gas fields. These include the Bonaire Dolomite, the Lower Ordovician Ranger Peak Formation of west Texas, and the Permian Clear Fork Formation of west Texas. Tracing dolomitizing fluid pathways may predict diagenetically controlled porosity trends in ancient rocks. Because porosity trends are associated with significant changes in petrophysical characteristics and fluid storage capacity at a between-well scale, this interpretation scheme may aid mapping of flow units in hydrocarbon reservoirs.

  3. Multimodal reservoir porosity simulation: An application to a tight oil reservoir

    NASA Astrophysics Data System (ADS)

    Sauvageau, Mathieu; Gloaguen, Erwan; Claprood, Maxime; Lefebvre, René; Bêche, Martin

    2014-08-01

    At appraisal stage of a reservoir characterization, a key step is the inference of the reservoir static properties, such as porosity. In this study, we present a new nested workflow that optimally integrates 3D acoustic impedance and geophysical log data for the estimation of the spatial distribution of reservoir porosity, which is applied to a tight sandstone oil reservoir located in Quebec, Canada. In this workflow, 3D seismic is the main source of spatial information. First, the statistical petrophysical relationship between acoustic impedance and reservoir porosity is established using collocated geophysical log data. Second, a conventional least-squares post-stack inversion of the impedance is computed on the seismic grid. The fit between well log data and numerically computed traces was found to be inaccurate. This leads to the third step, involving a post-stack stochastic impedance inversion using the same seismic traces not only to improve well and trace fit but also to estimate the uncertainty on the inverted impedances. Finally, a Bayesian simulation algorithm adapted to the estimation of a multi-modal porosity distribution is used to simulate realizations of porosity over the entire seismic grid. Results show that the over-smoothing effect of least-squares inversion has a major impact on resource evaluation, especially by not reproducing the high-valued tail of the porosity distribution. The adapted Bayesian algorithm combined with stochastic impedance inversion thus allows a better reproduction of the porosity distribution and improves estimation of the geophysical and geological uncertainty.

  4. Quantification of Organic Porosity and Water Accessibility in Marcellus Shale Using Neutron Scattering

    DOE PAGES

    Gu, Xin; Mildner, David F. R.; Cole, David R.; ...

    2016-04-28

    Pores within organic matter (OM) are a significant contributor to the total pore system in gas shales. These pores contribute most of the storage capacity in gas shales. Here we present a novel approach to characterize the OM pore structure (including the porosity, specific surface area, pore size distribution, and water accessibility) in Marcellus shale. By using ultrasmall and small-angle neutron scattering, and by exploiting the contrast matching of the shale matrix with suitable mixtures of deuterated and protonated water, both total and water-accessible porosity were measured on centimeter-sized samples from two boreholes from the nanometer to micrometer scale withmore » good statistical coverage. Samples were also measured after combustion at 450 °C. Analysis of scattering data from these procedures allowed quantification of OM porosity and water accessibility. OM hosts 24–47% of the total porosity for both organic-rich and -poor samples. This porosity occupies as much as 29% of the OM volume. In contrast to the current paradigm in the literature that OM porosity is organophilic and therefore not likely to contain water, our results demonstrate that OM pores with widths >20 nm exhibit the characteristics of water accessibility. In conclusion, our approach reveals the complex structure and wetting behavior of the OM porosity at scales that are hard to interrogate using other techniques.« less

  5. Tridimensional quantitative porosity characterization of three set calcium silicate-based repair cements for endodontic use.

    PubMed

    De Souza, Erika Thuanne Gonçalves; Nunes Tameirão, Michele Dias; Roter, Juliana Marins; De Assis, Joaquim Teixeira; De Almeida Neves, Aline; De-Deus, Gustavo André

    2013-10-01

    The aim of the this study was to quantitatively evaluate in three-dimensional (3D), the porosity degree of three improved silicate-based endodontic repair cements (iRoot BP Plus®, Biodentine®, and Ceramicrete) compared to a gold-standard calcium silicate bioactive cement (Pro Root® MTA). From each tested cement, four samples were prepared by a single operator following the manufacturer's instructions in terms of proportion, time, and mixing method, using cylindrical plastic split-ring moulds. The moulds were lubricated and the mixed cements were inserted with the aid of a cement spatula. The samples were scanned using a compact micro-CT device (Skyscan 1174, Bruker micro-CT, Kontich, Belgium) and the projection images were reconstructed into cross-sectional slices (NRecon v.1.6.9, Bruker micro-CT). From the stack of images, 3D models were rendered and the porosity parameters of each tested material were obtained after threshold definition by comparison with standard porosity values of Biodentine®. No statistically significant differences in the porosity parameters among the different materials were seen. Regarding total porosity, iRoot BP Plus® showed a higher percentage of total porosity (9.58%), followed by Biodentine® (7.09%), Pro Root® MTA (6.63%), and Ceramicrete (5.91%). Regarding closed porosity, Biodentine® presented a slight increase in these numbers compared to the other sealers. No significant difference in porosity between iRoot BP Plus®, Biodentine®, and Ceramicrete were seen. In addition, no significant difference in porosity between the new calcium silicate-containing repair cements and the gold-standard MTA were found.

  6. Pore morphology effect in microlog for porosity prediction in a mature field

    USGS Publications Warehouse

    Teh, W.J.; Willhite, G.P.; Doveton, J.H.; Tsau, J.S.

    2011-01-01

    In an matured field, developed during the 1950s, no porosity logs were available from sources other than invaded zone resistivity Rxo . The microresistivity porosity is calibrated with the core porosity to yield an accurate estimate of the porosity. However, the procedure of calibrating the porosity with Rxo for a linear regression model may not be predictive without an understanding of the pore types in the reservoir interval. A thorough investigation of the pore types, based on the lithofacies description obtained from the core analysis, and its role in obtaining a good estimate of porosity is demonstrated in the Ogallah field. Therefore, the objective of this paper is to separate the porosity-microlog data into pore-type based zones with characteristic cementation exponents (m) in this multi-petrotype reservoir with a complex mixture of Arbuckle dolomite and sandstone rock. The value of m is critical in making estimates of water saturation. "Rule of thumb" values of cementation might lead to errors in water saturation on either the optimistic or the pessimistic side. The rock types in the Ogallah contain interparticle/intercrystalline, vugs and fractures distributed through the rock-facies, which influence the values of cementation factor. We use the modern typed well to shed light on the Archie's equation parameter values. Rock fabric numbers and flow zone indices have been identified for classification of dolomite and sandstone, respectively. The analysis brings out characteristic cementation factors for distinct pore types in the Arbuckle rock. The porosity predictions The analysis results also compliment the petrofacies delineation using LDA in this complicated rock layout as a quality control of the statistical application. The comparison between the predicted and core porosities shows a significant improvement over using a single m value for carbonates and sandstones which will lead to improved description of a matured field. Copyright 2011, Society of

  7. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  8. Shearing fluid-filled granular media: A coupled discrete element - continuous approach

    NASA Astrophysics Data System (ADS)

    Goren, L.; Aharonov, E.; Sparks, D.; Toussaint, R.; Marder, E.

    2012-04-01

    Fluid-filled granular layers are abundant in the Earth's shallow crust as saturated soils and poorly consolidated hillslope material, and as fluid-filled fault gouge layers. When such grains-fluid systems are subjected to excitation by the passage of seismic waves, tectonic loading, or gravitational loading they exhibit a highly non-trivial dynamical behavior that may lead to instabilities in the form of soil liquefaction, debris flow mobilization, and earthquakes. In order to study the basic coupled mechanics of fluid-filled granular media and the dynamical processes that are responsible for the emergence of instabilities we develop a model that couples granular dynamics (DEM) algorithm with a continuous Eulerian grid-based solver. The two components of the model represent the two phases (grains and fluid) in two different scales. Each grain is represented by a single element in the granular dynamics component, where grains interact by elastic collisions and frictional sliding. The compressible pore fluid is represented on a coarser Darcy scale grid that is super-imposed over the grains layer. The pore space geometry set by the evolving granular packing is used to define smooth porosity and permeability fields, and the individual grain velocities are interpolated to define a smooth field of a solid-fraction velocity. The porosity, permeability, and solid velocity fields are used in the continuous fluid grid-based solver to find pore fluid velocity and pressure. Pore fluid pressure gradients are interpolated back from the fluid grid to individual grains, where they enter the grains force balance equation as seepage forces. Boundary conditions are specified separately for the two phases. For the pore fluid we test two end-member drainage conditions: completely drained system (with infinite boundary permeability) and completely undrained system (with zero boundary permeability). For the grains, two-dimensional time dependent stress and velocity conditions are

  9. Nanoscale transient porosity controls large-scale metamorphic fluid flow

    NASA Astrophysics Data System (ADS)

    Plümper, Oliver; Botan, Alexandru; Los, Catharina; Malthe-Sørenssen, Anders; Jamtveit, Bjørn

    2016-04-01

    The reaction of fluids with rocks is fundamental for Earth's dynamics as they facilitate heat/mass transfer and induce volume changes, weaknesses and instabilities in rock masses that localize deformation enabling tectonic responses to plate motion. During these fluid-rock interactions it is the ability of a rock to transmit fluid, its permeability, that controls the rates of metamorphic reactions. However, although some geological environments (e.g., sediments) are open to fluids, the majority of solid rocks (e.g., granites, elcogites, peridotites, etc.) are nearly impermeable. Surprisingly though, even in rocks that are nominally impermeable widespread fluid-rock interactions are observed leading to the question: How can fluids migrate through vast amounts of nominally impermeable rocks? Here we investigate one of the most wide-spread fluid-mediated metamorphic processes in the Earth's crust, the albitization of feldspatic rocks. We show that fluid flow and element mobilization during albitization is controlled by an interaction between grain boundary diffusion and reaction front migration through an interface-coupled dissolution-precipitation process. Using a combination of focused ion beam scanning electron microscopy (FIB-SEM)-assisted nanotomography combined with transmission electron microscopy (TEM) reveals that the porosity is dictated by pore channels with a pore diameter ranging between 10 to 100 nm. Three-dimensional visualization of the feldspar pore network reveals that the pore channels must have been connected during the replacement reaction. Analysis of the pore aspect ratios suggests that a Rayleigh-Taylor-type instability associated to surface energy minimization caused the disconnection of the pore channels. Fluid transport in nanometer-sized objects with at least one characteristic dimension below 100 nm enables the occurrence of physical phenomena that are impossible at bigger length scales. Thus, on the basis of our microstructural

  10. Brittle and semibrittle creep in a low porosity carbonate rock

    NASA Astrophysics Data System (ADS)

    Nicolas, Aurélien; Fortin, Jérôme; Regnet, Jean-Baptiste; Dimanov, Alexandre; Guéguen, Yves

    2016-04-01

    The mechanical behavior of limestones at room temperature is brittle at low confining pressure and becomes semi-brittle with the increase of the confining pressure. The brittle behavior is characterized by a macroscopic dilatancy due to crack propagation, leading to a stress drop when cracks coalesce at failure. The semi-brittle behavior is characterized by diffuse deformation due to intra-crystalline plasticity (dislocation movements and twinning) and microcracking. The aim of this work is to examine the influence of pore fluid and time on the mechanical behavior. Constant strain rate triaxial deformation experiments and stress-stepping creep experiments were performed on white Tavel limestone (porosity 14.7%). Elastic wave velocity evolutions were recorded during each experiment and inverted to crack densities. Constant strain rate triaxial experiments were performed for confining pressure in the range of 5-90 MPa. For Pc≤55 MPa our results show that the behavior is brittle. In this regime, water-saturation decreases the differential stress at the onset of crack propagation and enhances macroscopic dilatancy. For Pc≥70 MPa, the behavior is semi-brittle. Inelastic compaction is due to intra-crystalline plasticity and micro-cracking. However, in this regime, our results show that water-saturation has no clear effect at the onset of inelastic compaction. Stress stepping creep experiments were performed in a range of confining pressures crossing the brittle-ductile transition. In the brittle regime, the time-dependent axial deformation is coupled with dilatancy and a decrease of elastic wave velocities, which is characteristic of crack propagation and/or nucleation. In the semi-brittle regime, the first steps are inelastic compactant because of plastic pore collapse. But, following stress steps are dilatant because of crack nucleation and/or propagation. However, our results show that the axial strain rate is always controlled by plastic phenomena, until the last

  11. Porosity, Pore Size, and Permeability of Sediments from Site C0002, IODP Expedition 338

    NASA Astrophysics Data System (ADS)

    Dugan, B.; Huepers, A.; Song, I.; Kitajima, H.; Esteban, L.

    2013-12-01

    Mercury injection capillary pressure (MICP) measurements were made on cuttings and core samples from Integrated Ocean Drilling Program (IODP) Site C0002 to evaluate porosity, pore throat size, and permeability of mud(stone) at the centerpiece drill site of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). Core samples from 221-464 meters below sea floor (mbsf) in the Kumano forearc basin have MICP-determined porosities from 40-56%, median pore radii from 0.077-0.205 microns, and permeability from 3.3x10-10 - 2.0x10-9 m2. The porosity of these core samples is similar to shipboard porosity determined from moisture and density (MAD) analyses. During IODP Expedition 338 cuttings samples were recovered from ~865-2005 mbsf during riser drilling at Site C0002F. MICP analyses of cuttings samples, greater than 4 mm size fraction, from 928-1980 mbsf in the inner wedge of the accretionary prism constrain porosities from 21-44%, median pore radii from 0.021-0.032 microns, and permeability from 1.2x10-11 - 1.6x10-10 m2. The porosity of these cuttings samples is consistently lower than the MAD-determined porosity on cuttings from the >4mm size fraction, however the values are consistent with core-based, MAD-derived porosity from Hole C0002B above 1057 mbsf and with cuttings-based, MAD-derived porosity on select samples from 1700-2000 mbsf that were determined to be intact formation and not influenced by drilling disturbance. These results suggest that select formation cuttings or MICP-analyses can help define in situ porosity. Additional post-expedition research will be used to better understand the ability of MICP data to define mudstone permeability and to constrain permeability-porosity and permeability-grain size-pore throat relations for sediments at Site C0002. A detailed model of permeability and porosity behavior will inform modeling studies of pore pressure generation and fluid and heat transport.

  12. Porosity estimates of the upper crust in the Endeavour segment of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Kim, E.; Toomey, D. R.; Hooft, E. E. E.; Wilcock, W. S. D.; Weekly, R. T.; Lee, S. M.; Kim, Y.

    2015-12-01

    We estimate upper crustal porosity variations using the differential effective medium (DEM) theory to interpret the observed seismic velocity variations for the Endeavour segment of the Juan de Fuca Ridge, an intermediate spreading center [Weekly et al., 2014]. We use six P-wave vertical velocity profiles averaged within 5 km × 10 km areas to estimate the porosity at depths from 0.4 km to 2 km. The profile regions cover on-axis, east and west flanks of the central Endeavour segment and three regions of the segment ends including the Endeavour-West Valley (E-WV) and the Cobb overlapping spreading centers (OSCs) and the relict Middle Valley. At the segment center, our calculated porosities on-axis and on the east and west flanks agree well with the apparent bulk porosities measured in Hole 504B at intermediate-spreading Costa Rica Rift [Becker, 1990] and decrease from 5-15% to 2-7% from 0.5 km to 1 km depth and seal by 2 km depth. At all depths, our calculated porosities on the east and west flanks are lower than those on-axis by ~1.3-3%. This indicates the infilling of cracks by mineral precipitation associated with near-axis hydrothermal circulation [Newman et al., 2011]. At the segment ends, upper crustal velocities are lower than those in the segment center at depths < 2 km. These lower velocities are attributed to higher porosities (10-20% at 0.4 km decreasing to 3-6% at 2 km depth). This may indicate that fracturing in the OSCs strongly affects porosity at shallow depths. Between 0.7 km and 1 km, porosities estimated in all regions using pore aspect ratios of 0.05, 0.1 and 0.2 are higher than those from Hole 504B indicating that the aspect ratio of cracks may be smaller than 0.05. There also appears to be a spreading rate dependence to upper crustal porosity structure. On-axis at the Endeavour segment, the calculated porosities from 0.4 km to 2 km are higher than those at the Lucky Strike segment, a slow spreading center [Seher et al., 2010]. Specifically at 2

  13. The influence of porosity and vesicle size on the brittle strength of volcanic rocks and magma

    NASA Astrophysics Data System (ADS)

    Heap, Michael J.; Xu, Tao; Chen, Chong-feng

    2014-09-01

    Volcanic rocks and magma display a wide range of porosity and vesicle size, a result of their complex genesis. While the role of porosity is known to exert a fundamental control on strength in the brittle field, less is known as to the influence of vesicle size. To help resolve this issue, here, we lean on a combination of micromechanical (Sammis and Ashby's pore-emanating crack model) and stochastic (rock failure and process analysis code) modelling. The models show, for a homogenous vesicle size, that an increase in porosity (in the form of circular vesicles, from 0 to 40 %) and/or vesicle diameter (from 0.1 to 2.0 mm) results in a dramatic reduction in strength. For example, uniaxial compressive strength can be reduced by about a factor of 5 as porosity is increased from 0 to 40 %. The presence of vesicles locally amplifies the stress within the groundmass and promotes the nucleation of vesicle-emanating microcracks that grow in the direction of the applied macroscopic stress. As strain increases, these microcracks continue to grow and eventually coalesce leading to macroscopic failure. Vesicle clustering, which promotes the overlap and interaction of the tensile stress lobes at the north and south poles of neighbouring vesicles, and the increased ease of microcrack interaction, is encouraged at higher porosity and reduces sample strength. Once a microcrack nucleates at the vesicle wall, larger vesicles impart higher stress intensities at the crack tips, allowing microcracks to propagate at a lower applied macroscopic stress. Larger vesicles also permit a shorter route through the groundmass for the macroscopic shear fracture. This explains the reduction in strength at higher vesicle diameters (at a constant porosity). The modelling highlights that the reduction in strength as porosity or vesicle size increases is nonlinear; the largest reductions are observed at low porosity and small vesicle diameters. In detail, we find that vesicle diameter can play an

  14. Physicochemical Properties and Surfaces Morphologies Evaluation of MTA FillApex and AH Plus

    PubMed Central

    Borges, Álvaro Henrique; Orçati Dorileo, Maura Cristiane Gonçales; Villa, Ricardo Dalla; Borba, Alexandre Meireles; Semenoff, Tereza Aparecida Delle Vedove; Guedes, Orlando Aguirre; Estrela, Cyntia Rodrigues Araújo; Bandeca, Matheus Coelho

    2014-01-01

    The solubility, pH, electrical conductivity, and radiopacity of AH Plus and MTA FillApex were evaluated. In addition, the surfaces morphologies of the sealers were analyzed by using scanning electron microscopy. For pH test, the samples were immersed in distilled water at different periods of time. The same solution was used for electrical conductivity measurement. The solubility and radiopacity were evaluated according to ANSI/ADA. Statistical analyses were carried out at 5% level of significance. MTA FillApex presented higher mean value for solubility and electrical conductivity. No significant difference was observed in the mean values for pH reading. AH Plus presented higher radiopacity mean values. MTA FillApex presented an external surface with porosities and a wide range of sizes. In conclusion, the materials fulfill the ANSI/ADA requirements when considering the radiopacity and solubility. AH Plus revealed a compact and homogeneous surface with more regular aspects and equal particle sizes. PMID:24883413

  15. Confined-unconfined changes above longwall coal mining due to increases in fracture porosity

    SciTech Connect

    Booth, C.J.

    2007-11-15

    Subsidence and strata movement above longwall (total extraction) coal mines produce complex hydrologic responses that can occur independently of drainage to the mine. One response is dewatering from confined to unconfined conditions in bedrock aquifers as a result of loss of water into new void space created by fracture and bedding separations. This dewatering process has been little studied but accounts for several hydraulic and geochemical effects of longwall mining. This article presents a conceptual model of the process and reviews evidence from case studies. Confined bedrock aquifers in subsiding zones exhibit dramatically steep head drops because of the low value of confined storage coefficients relative to the volume of water drained into the new fracture void space. The aquifer changes rapidly to an unconfined condition. Tight units to which air entry is restricted may even develop negative water pressures. In the unconfined state, sulfide minerals present in the strata readily oxidize to soluble hydrated sulfates. When the aquifer re-saturates, these salts are rapidly mobilized and produce a flush of increased sulfate and total dissolved solids (TDS) levels. Observations made in our previous studies in Illinois are consistent with the confined-unconfined model and include rapid head drops, changes to unconfined conditions, and increases in sulfate and TDS during re-saturation of a sandstone aquifer. Studies reported from the Appalachian coalfield show aspects consistent with the model, but in this high-relief fractured setting it is often difficult to distinguish aquifers from aquitards, confined from unconfined states, and the fracture-porosity cause of head drops from several others that occur during mine subsidence.

  16. Diagenesis and porosity evolution of the Yongningzheng Formation grainstone (Lower Triassic) in southwest Guizhou, People's Republic of China

    SciTech Connect

    Ye, D.S.; Lui, S.H.; Zeng, Z.D.; Chen, Y.B.

    1988-02-01

    The Youngningzheng Formation (Lower Triassic) is a shallow platform deposit consisting of micrites interbedded with oolitic grainstones. The diagenetic history and porosity evolution of these grainstones are very complicated. Both near-surface and burial diagenesis are obvious, based on both petrographical and geochemical studies. The most important processes that influence porosity evolution are cementation, dissolution, and compaction. The primary porosity was about 40%. The porosity after the submarine cementation and compaction was about 25%. The porosity was 35% after freshwater dissolution. After the freshwater phreatic cementation, the porosity decreased to about 10%. The porosity was about 5% after burial cementation. During the period of oil emplacement, the porosity (i.e., the porosity of accumulation stage) was only 4-5% after stylolitization and associated infrequent dissolution. The present porosity (outside oil-bearing area) is just 1-2% after continuous cementation. The authors consider that neither primary nor present porosity (outside oil-bearing area) can be used to evaluate the reservoir quality. In order to evaluate reservoir quality correctly, only the porosity of accumulation stage can be used.

  17. Filled nanoporous surfaces: controlled formation and wettability.

    PubMed

    Bittoun, Eyal; Marmur, Abraham; Ostblom, Mattias; Ederth, Thomas; Liedberg, Bo

    2009-10-20

    The controlled filling of hydrophobic nanoporous surfaces with hydrophilic molecules and their wetting properties are described and demonstrated by using thiocholesterol (TC) self-assembled monolayers (SAMs) on gold and mercaptoundecanoic acid (MUA) as the filling agent. A novel procedure was developed for filling the nanopores in the TC SAMs by immersing them into a "cocktail" solution of TC and MUA, with TC in huge excess. This procedure results in an increasing coverage of MUA with increasing immersion time up to an area fraction of approximately 23%, while the amount of TC remains almost constant. Our findings strongly support earlier observations where linear omega-substituted alkanethiols selectively fill defects (nanopores) in the TC SAM (Yang et al. Langmuir 1997, 12, 1704-1707). They also support the formation of a homogeneously mixed SAM, given by the distribution of TC on the gold surface, rather than of a phase-segregated overlayer structure with domains of varying size, shape, and composition. The wetting properties of the filled SAMs were investigated by measuring the most stable contact angle as well as contact angle hysteresis. It is shown that the most stable contact angle is very well described by the Cassie equation, since the drops are much larger than the scale of chemical heterogeneity of the SAM surfaces. In addition, it is demonstrated that contact angle hysteresis is sensitive to the chemical heterogeneity of the surface, even at the nanometric scale.

  18. The effect of porosity on fault slip mechanisms at East Pacific Rise transform faults: insight from observations and models at the Gofar Fault (Invited)

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.; Lizarralde, D.; Behn, M. D.; Collins, J. A.

    2013-12-01

    In this study, we combine recent local observations and numerical models to show that Pacific oceanic transform faults contain consistent high-porosity damage zones that extend throughout the crust within localized regions along the fault. Heterogeneity in fault zone material properties associated with along-strike changes in porosity and fluid-related effects may promote variations in fault-slip mechanisms, with slow, aseismic slip in some fault segments and fast, seismic rupture in others. Ocean bottom seismometer observations made during the 2008 rupture process of the Gofar fault (4° S on the East Pacific Rise), in combination with ~25 years of teleseismic observations, indicate significant along-strike variability in fault slip mechanisms; discrete fault segments fail regularly in Mw 6.0 earthquakes, and seismogenic segments are separated by velocity-strengthening, ~10-km-long rupture barriers that appear to fail during earthquake swarms, likely accompanied by aseismic slip. 3D models of the Gofar fault thermal structure suggest that swarm microearthquake hypocenters within the rupture barrier zones occur at depths greater than would be expected to sustain brittle failure, and at temperatures too hot to exhibit stick-slip behavior in lower crust and upper mantle rocks. This observation suggests that some mechanism leads to enhanced cooling within discrete zones along the fault. The seismic structure of the Gofar rupture barrier region is imaged using P-wave traveltime tomography as a ~2-km-wide low velocity zone that extends through the entire crust. Reduced velocities can be explained if the plate-boundary region is composed of fault material with enhanced fluid-filled porosity (1.5-8%). Enhanced porosity, and associated increased hydrothermal heat transport deep within the crust at Gofar is also consistent with the observed deep seismicity and apparently cooler fault structure in distinct fault segments. Dilatency strengthening is one mechanism that may be

  19. Measurement of Meteorite Density, Porosity and Magnetic Susceptibility: Fast, Non- destructive, Non-contaminating and Very Informative

    NASA Astrophysics Data System (ADS)

    Macke, R. J.; Britt, D. T.; Consolmagno, G. J.

    2009-05-01

    The development of the "glass bead" method [1] for measuring bulk density, coupled with other fast, non- destructive and non-contaminating methods for measuring grain density and magnetic susceptibility, has enabled broad surveys of large meteorite collections. We have employed these methods extensively on meteorites in numerous collections, including those at the Vatican, the American Museum of Natural History (New York), the National Museum of Natural History (Washington, DC), Texas Christian University, University of New Mexico, and Arizona State University. We present here a summary of some of the findings to date. Using the glass bead method, the meteorite is placed into a container which is then filled entirely with small (sub- millimeter) glass beads. The beads behave collectively as an Archimedean fluid, flowing around the sample to fill the empty space in the container. Through mass measurement, the volume displaced by the sample can be determined. Grain density is determined via helium ideal-gas pycnometry. Magnetic susceptibility is determined using a commercially available hand-held device [2]. Among notable findings to date, grain density and magnetic susceptibility together can distinguish H, L and LL ordinary chondrite falls into clearly distinct groupings [3]. On the other hand, enstatite chondrites of EH and EL subgroups are indistinguishable in these properties, indicating that EH and EL do not differ significantly in iron content [4]. Carbonaceous chondrites can have porosities that are significantly higher than ordinary chondrites and (especially for aqueously altered meteorites) lower density, though these also vary according to subgroups [5]. References: [1] Consolmagno and Britt, 1998. M&PS 33, 1231-1240. [2] Gattacceca et al., 2004. GJI 158, 42-49. [3] Consolmagno et al., 2006. M&PS 41, 331-342. [4] Macke et al., 2009. LPSC 40, 1598. [5] Consolmagno et al., 2008. MetSoc 71, 5038.

  20. Depositional environments, diagenesis, and porosity of upper cretaceous volcanic-rich Tokio sandstone reservoirs, Haynesville Field, Clairborne Parish, Louisiana

    SciTech Connect

    Clark, W.J.

    1995-10-01

    Tokio Formation sandstones produce oil from volcanic-rich to quartzose lithic sandstones in the Haynesville Field. The Tokio interval is approximately 210 feet thick and has been divided into four sandstone zones separated by shales or scoured contacts. In ascending order, the four zones are the RA, S3, S2, and S1. The RA is composed of quartzose sublitharenites inferred to have been deposited in delta front bars and distributary channels. The upper three zones are composed of sublitharenite and feldspathic litharenite to quartzose litharenite. The upper sands are interpreted to have been deposited in littoral environments including storm influenced shelf, tidal flats and channels, and barrier island/strand plain. The diagenesis of these sands is strongly related to composition: greater percentages of cements and secondary porosity occur in lithic-rich sandstones. Diagenetic cements in quartzose sandstones are mainly quartz overgrowths with minor early K-spar overgrowths on plagioclase, early chlorite-rims, and late patchy calcite, pyrite, and rare dolomite and siderite. Diagenesis in lithic-rich sands includes greater amounts of chlorite rim and pore-filling kaolinite cements and less quartz-overgrowth and other cements. The effect of the original mineralogy and diagenetic minerals on wireline logs includes: (1) reduction of SP due to cements, (2) increase in GR response due to K-spar and volcanic detritus, (3) higher resistivity due to carbonate minerals, and (4) increase in irreducible water saturation due to pore-lining and pore-filling clay. Thus, potential reservoir zones with lithic-rich sandstones like the Tokio could be overlooked in many areas around the world.

  1. Measurement of porosity in a composite high explosive as a function of pressing conditions by ultra-small-angle neutron scattering with contrast variation

    SciTech Connect

    Mang, Joseph Thomas; Hjelm, Rex P; Francois, Elizabeth G

    2009-01-01

    We have used ultra-small-angle neutron scattering (USANS) with contrast variation to measure the porosity (voids and binder-filled regions) in a composite high explosive, PBX 9501, formulated with a deuterated binder. Little is known about the microstructure of pressed PBX 9501 parts and thus how it is affected by processing. Here, we explore the effect of varying the pressing intensity on the PBX 9501 microstructure. Disk-shaped samples of PBX 9501 were die-pressed with applied pressures ranging between 10,000 and 29,000 psi at 90 C. Five samples were prepared at each pressure that differed in the fraction of deuterated binder, facilitating variation of the neutron scattering length density contrast ({Delta}{rho}) and thus, the resolution of microstructural details. The sample composition was determined by calculation of the Porod Invariant as a function of {Delta}{rho} and compared with compositional estimates obtained from the bulk sample density. Structural modeling of the USANS data, at different levels of contrast, assuming both spherical and cylindrical morphologies, allowed the mean size and size distribution of voids and binder-filled regions to be determined. A decrease in the mean diameter of binder-filled regions was found with increasing pressing intensity, while the mean void diameter showed no significant change.

  2. Porosity detection in ceramic armor tiles via ultrasonic time-of-flight

    SciTech Connect

    Margetan, Frank J.; Richter, Nathaniel; Jensen, Terrence

    2011-06-23

    Some multilayer armor panels contain ceramic tiles as one constituent, and porosity in the tiles can affect armor performance. It is well known that porosity in ceramic materials leads to a decrease in ultrasonic velocity. We report on a feasibility study exploring the use of ultrasonic time-of-flight (TOF) to locate and characterize porous regions in armor tiles. The tiles in question typically have well-controlled thickness, thus simplifying the translation of TOF data into velocity data. By combining UT velocity measurements and X-ray absorption measurements on selected specimens, one can construct a calibration curve relating velocity to porosity. That relationship can then be used to translate typical ultrasonic C-scans of TOF-versus-position into C-scans of porosity-versus-position. This procedure is demonstrated for pulse/echo, focused-transducer inspections of silicon carbide (SiC) ceramic tiles.

  3. Effects of Support Structure Porosity on the Drift Accumulation Surrounding an Elevated Building

    DTIC Science & Technology

    2012-09-01

    the MAPO building the concentrations tended to be lower than field observations. Though it is difficult to get an exact similitude be- tween reduced...Elevated building Elevated building substructure porosity Mathematical modeling Physical modeling Snow drifting Wind tunnel experiments

  4. Effect of Porosity on Photocatalytic Activity of Plasma-Sprayed TiO2 Coating

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Chaudhary, Ujwal; Das, Santanu; Godavarty, Anuradha; Agarwal, Arvind

    2013-10-01

    The effect of porosity on photocatalytic activity of plasma-sprayed TiO2 coating on steel substrate is studied by varying processing parameters viz. plasma power and powder feed rate. The relationship between porosity content and methylene blue (MB) dye decomposition rate was established to correlate coating microstructure and its photocatalytic activity. The coating with the highest porosity content exhibited best photocatalytic efficiency. The same processing parameters were used to deposit TiO2 coating on FTO glass. The photocatalytic activity of TiO2 coating on FTO was 2.5 times better than TiO2 coating on the steel substrate. TiO2 coating on FTO glass contains bimodal porosity distribution (micropores and submicron pores) which accelerated MB decomposition by accelerated diffusion of ionic species.

  5. Characterization of porosity via secondary reactions. Final technical report, 1 September 1991--30 November 1995

    SciTech Connect

    Calo, J.M.; Zhang, L.; Hall, P.J.; Antxustegi, M.

    1997-09-01

    A new approach to the study of porosity and porosity development in coal chars during gasification was investigated. This approach involves the establishment of the relationships between the amount and type of surface complexes evolved during post-activation temperature programmed desorption (TPD), and the porosity, as measured by gas adsorption and small angle neutron scattering (SANS) techniques. With this new method, the total surface area and micropore volume can be determined by the interpretation of post-activation TPD spectra. The primary conclusion of this work is that it is possible to predict total surface area and micropore volume from TPD spectra. From the extended random pore model, additional information about the micropore surface area, the nonmicroporous surface area, and the mean micropore size development as a function of reaction time (or burn-off) can also be predicted. Therefore, combining the TPD technique and the extended random pore model provides a new method for the characterization of char porosity.

  6. Porosity determination of ceramic materials by digital image analysis--a critical evaluation.

    PubMed

    von Bradke, M; Gitzhofer, F; Henne, R

    2005-01-01

    Measuring the porosity of materials by digital image analysis of micrographs is a well-established and convenient method for the testing of metallic samples. However, when applied to ceramic materials, this method has been shown to be much less reliable and poorly reproducible. The purpose of this present work is to clarify the reason for this deficiency, involving many porosity measurements, performed on plasma-sprayed zirconia, under systematically varied microscopic imaging conditions, and the porosities being calculated using various evaluation methods. Comparison between of the results has shown that the present state of the image analysis method is not satisfactory for absolute porosity measurements on ceramic materials. It can be useful as a convenient tool for comparative measurements, however, if the imaging conditions maintained in the microscope and the evaluation method are held to be exactly identical.

  7. Fiber-optic sensor for the monitoring of moisture ingress and porosity of concrete

    NASA Astrophysics Data System (ADS)

    Yeo, T. L.; Eckstein, D.; McKinley, B.; Boswell, L. F.; Sun, T.; Grattan, K. T.

    2005-05-01

    A fibre-optic embedded sensor using a polymer-coated fibre Bragg grating (FBG) was developed and used to detect the ingress of moisture in concrete specimens of different porosity. Applications to structural health monitoring are discussed.

  8. Percolating porosity in ultrafine grained copper processed by High Pressure Torsion

    SciTech Connect

    Wegner, Matthias Leuthold, Jörn; Peterlechner, Martin; Divinski, Sergiy V. Wilde, Gerhard; Setman, Daria; Zehetbauer, Michael; Pippan, Reinhard

    2013-11-14

    Defect structures in copper of different purity (nominally 99.99 and 99.999 wt. %) deformed via High Pressure Torsion (HPT) with varying processing parameters are investigated utilizing the radiotracer diffusion technique. While the degree of deformation is kept constant, the effects of applied quasi-hydrostatic pressure, processing temperature, post-deformation annealing treatments, and of the impurity concentration on the deformed samples are analyzed in terms of the formation of interconnected internal porosity. Furthermore, the anisotropy of the developing porosity network is examined. The porosity channels occurred to be interconnected along the direction parallel to the surface normal with a volume fraction of the order of a few ppm while no long-range penetration along the internal porosity could be detected when measured along the azimuthal or radial directions of a HPT processed sample.

  9. Passive porosity with free and fixed separation on a tangent-ogive forebody

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Banks, Daniel W.; Bauer, Steven X. S.

    1994-01-01

    Despite the extensive experimental and computational data base in the literature on passive porosity, no clear explanation of the governing flow physics exists. It is theorized that the positive porosity concept modifies the external pressure loading by allowing communication between high- and low-pressure regions on the external surface. This study determines the dominant flow phenomena that govern the effectiveness of passive porosity. It aims to assess the contribution of each phenomenon as related to a porous slender axisymmetric forebody. To assess the influence of the mass transfer and pressure equalization phenomena on the effectiveness of passive porosity on slender axisymmetric forebodies, strakes were attached to the 5.0-caliber solid and porous forebodies to force crossflow separation. Longitudinal force and moment data were obtained at a Mach number of 0.1 over an angle-of-attack range of 0 to 55 deg.

  10. Types of secondary porosity of carbonate rocks in injection and test wells in southern peninsular Florida

    USGS Publications Warehouse

    Duerr, A.D.

    1995-01-01

    The types of secondary porosity present in carbonate injection intervals and in the overlying carbonate rocks were determined at 11 injection well sites and 3 test well sites in southern peninsular Florida. The hydrogeologic system consists of a thick sequence of carbonate rocks overlain by clastic deposits. Principal hydrogeologic units are the surficial aquifer system, the intermediate aquifer system or the intermediate confining unit,the Floridan aquifer system, and the sub-Floridan confining unit.The concept of apparent secondary porosity was used in this study because the secondary porosity features observed in a borehole television survey could have been caused by geologic processes as well as by drilling activities. The secondary porosity features identified in a television survey were evaluated using driller's comments and caliper, flowmeter, and temperature logs. Borehole intervals that produced or received detectable amounts of flow, as shown by flowmeter and temperature logs, provided evidence that the secondary porosity of the interval was spatially distributed and interconnected beyond the immediate vicinity of a borehole and, thus, was related to geologic processes. Features associated with interconnected secondary porosity were identified as effective secondary porosity. Fracture porosity was identified as the most common type of effective secondary porosity and was observed predominantly in dolomite and dolomitic limestone. Cavity porosity was the least common type of effective secondary porosity at the study sites. In fact, of the more than 17,500 feet of borehole studied a total of only three cavities constituting effective secondary porosity were identified at only two sites. These cavities were detected in dolomite rocks. Most apparent cavities were caused by drilling-induced collapse of naturally fractured borehole walls. Also, fractures usually were observed above and below cavities. The majority of vugs observed in the television surveys did

  11. Porosity of dental gypsum-bonded investments in setting and heating process.

    PubMed

    Asaoka, Kenzo; Bae, Ji-Young; Lee, Hae-Hyoung

    2012-02-03

    The porosity of gypsum-bonded investments for set and heated compacts was measured and theoretically computed quantitatively, because porosity is an effective factor for determining the strength, setting/heating expansion, and permeability of compacts at casting. A helium gas pycnometer was used to measure the solid volume of fine powders, powder-water mixtures, and porous compacts. The compositions of the conventional cristobalite investment and rapid-heating type investment were estimated from the measured solid densities of the as-received powders and the set investments. The porosity and water content of the set investments were determined from the experimental data. Excess water content in the set investment was calculated in relation to the elapsed time from the start of mixing with water. The experimental porosities of the set and heated investments were about 40% for dry set >compacts and about 50% for fired compacts, which well agreed with the numerically computed estimations, respectively.

  12. Slotted Polyimide-Aerogel-Filled-Waveguide Arrays

    NASA Technical Reports Server (NTRS)

    Rodriguez-Solis, Rafael A.; Pacheco, Hector L.; Miranda, Felix A.; Meador, Mary Ann B.

    2013-01-01

    Polyimide aerogels were considered to serve as a filling for millimeter-wave waveguides. While these waveguides present a slightly higher loss than hollow waveguides, they have less losses than Duroid substrate integrated waveguides (less than 0.15 dB at Ka-band, in a 20 mm section), and exhibit an order of magnitude of mass reduction when compared to commercial waveguides. A Ka-band slotted aerogel-filled-waveguide array was designed, which provided the same gain (9 dBi) as its standard waveguide counterpart, and a slotted aerogel-filled-waveguide array using folded-slots was designed for comparison, obtaining a gain of 9 dB and a bandwidth of 590 MHz.

  13. One-dimensional Gromov minimal filling problem

    NASA Astrophysics Data System (ADS)

    Ivanov, Alexandr O.; Tuzhilin, Alexey A.

    2012-05-01

    The paper is devoted to a new branch in the theory of one-dimensional variational problems with branching extremals, the investigation of one-dimensional minimal fillings introduced by the authors. On the one hand, this problem is a one-dimensional version of a generalization of Gromov's minimal fillings problem to the case of stratified manifolds. On the other hand, this problem is interesting in itself and also can be considered as a generalization of another classical problem, the Steiner problem on the construction of a shortest network connecting a given set of terminals. Besides the statement of the problem, we discuss several properties of the minimal fillings and state several conjectures. Bibliography: 38 titles.

  14. Processing and Characterization of Porous Ti2AlC with Controlled Porosity and Pore Size

    DTIC Science & Technology

    2012-09-11

    fabricated by spark plasma sintering , were also characterized. The effects of porosity and/or pore size on the room temperature elastic moduli...pressureless- sintered without NaCl pore former, or fabricated by spark plasma sintering , were also characterized. The effects of porosity and/or pore size...as well as several samples sintered using spark plasma sintering (SPS). Furthermore, we demon- strate that the developed methodology can be implemented

  15. Study of spatial variation in soil porosity in sections of microtomography images

    NASA Astrophysics Data System (ADS)

    Furtado Pereira, Suenon; Moraes, Maria Helena

    2014-05-01

    Computed X-ray microtomography (μ - CT) has proved quite useful for quantitative soil analysis technique because it provides microstructural parameters in soil porosity, providing sampling a series of two-dimensional images with micrometer spatial resolution, thus enabling study the spatial variation of porosity between images depending on the texture and soil management. Soil samples from Red Nitosol class (56% clay and 13% sand) under the managements of forest and cultivation of annual crops were collected, and from the class Typic Quartzipisamment (7% clay and 91% sand) under the forest managements and pasture, being three samples collected for each type of management. The images were obtained with microtomógrafo Skyscan model 1172. However 2400 two-dimensional images were analyzed by management with spatial resolution of 12μm.pixel- 1. The image analysis counts only macro and mesopores. For image analysis under Red Nitosol with forest management were observed average porosity of 25.83% with a standard deviation of 3.08 % between the images and on management of annual crops the porosity was 11.68 % with a shift 0.87% standard. For the area under Typic Quartzipisamment with forest management the value of average porosity was 28.58% with the standard deviation 1.93% and the pasture porosity was 23.01% with a standard deviation of 0.58%. The results show that the variation of porosity in the sections of images was higher in the clayey soil and the forest management has greater variation of porosity in two textures studied, so to microtomographic analyzes, is necessary to collect a large number of samples to better represent these soil class texture and use.

  16. Interaction of Porosity with an Advancing Solid/Liquid Interface: a Real-Time Investigation

    NASA Technical Reports Server (NTRS)

    Sen, S.; Kaukler, W.; Catalina, A.; Stefanescu, D.; Curreri, P.

    1999-01-01

    Problems associated with formation of porosity during solidification continue to have a daily impact on the metal forming industry. Several past investigations have dealt with the nucleation and growth aspects of porosity. However, investigations related to the interaction of porosity with that of a solidification front has been limited mostly to organic analogues. In this paper we report on real time experimental observations of such interactions in metal alloys. Using a state of the art X-Ray Transmission Microscope (XTM) we have been able to observe and record the dynamics of the interaction. This includes distortion of the solid/liquid interface near a poro.sity, solute segr,egation patterns surrounding a porosity and the change in shape of the porosity during interaction with an advancing solid/liquid interface. Results will be presented for different Al alloys and growth conditions. The experimental data will be compared to theory using a recently developed 2D numerical model. The model employs a finite difference approach where the solid/liquid interface is defined through the points at which the interface intersects the grid lines. The transport variables are calculated at these points and the motion of the solidification front is determined by the magnitude of the transport variables. The model accounts for the interplay of the thermal and solutal field and the influence of capilarity to predict the shape of the solid/liquid interface with time in the vicinity of porosity. One can further calculate the perturbation of the solutal field by the presence of porosity in the melt.

  17. Electrical resistivity and porosity structure of the upper Biscayne Aquifer in Miami-Dade County, Florida

    NASA Astrophysics Data System (ADS)

    Whitman, Dean; Yeboah-Forson, Albert

    2015-12-01

    Square array electrical soundings were made at 13 sites in the Biscayne Aquifer distributed between 1 and 20 km from the shoreline. These soundings were modeled to investigate how resistivity varies spatially and with depth in the upper 15 m of the aquifer. Porosity was estimated from the modeled formation resistivity and observed pore fluid resistivity with Archie's Law. The models were used to interpolate resistivity and porosity surfaces at -2, -5, -8, and -15 m elevations. Modeled resistivity in the unsaturated zone is generally higher than 300 Ω m with the resistivity at sites with thick unsaturated zones greater than 1000 Ω m. Resistivity in the saturated zone ranges from 30 to 320 Ω m. At many sites in the western portions of the study area, resistivity is constant or increases with depth whereas sites in the center of the Atlantic Coastal Ridge exhibit a distinct low resistivity zone (ρ < 45 Ω m) at elevations ranging between -5 and -10 m. At one site near the shore of Biscayne Bay, the resistivity is less than 10 Ω m at -5 m elevation reflecting the presence of salt water in the aquifer. The estimated porosity ranges between 14% and 71% with modal values near 25%. The porosity structure varies both with depth and spatially. Western sites exhibit a high porosity zone at shallow depths best expressed in a NE-SW trending zone of 40-50% porosity situated near the western margin of the Atlantic Coastal Ridge. This zone roughly corresponds in depth with the Q5 chronostratigraphic unit of the Miami Fm. which constitutes the upper flow unit of the Biscayne Aquifer. The highest porosity (>50%) is seen at elevations below -5 m at sites in the center of the Atlantic Coastal Ridge and likely corresponds to solution features. The general NE-SW trend of the resistivity and porosity structure suggests a causal connection with the Pleistocene paleogeography and sedimentary environments.

  18. Simultaneous measurement of rock permeability and effective porosity using laser-polarized noble gas NMR

    NASA Astrophysics Data System (ADS)

    Wang, R.; Mair, R. W.; Rosen, M. S.; Cory, D. G.; Walsworth, R. L.

    2004-08-01

    We report simultaneous measurements of the permeability and effective porosity of oil-reservoir rock cores using one-dimensional NMR imaging of the penetrating flow of laser-polarized xenon gas. The permeability result agrees well with industry standard techniques, whereas effective porosity is not easily determined by other methods. This NMR technique may have applications to the characterization of fluid flow in a wide variety of porous and granular media.

  19. Polarization splitter based on dual core liquid crystal-filled holey fiber

    NASA Astrophysics Data System (ADS)

    Wang, Er-Lei; Jiang, Hai-Ming; Xie, Kang; Chen, Chun; Hu, Zhi-Jia

    2016-09-01

    Through filling the liquid crystal into the air holes of a dual-core holey fiber with a simple structure, the transmission mechanism of the fiber is changed from total internal reflection to photonic bandgap (PBG), and a polarization splitter based on the liquid crystal-filled dual-core PBG holey fiber is investigated. The results demonstrate that, by setting appropriate geometrical parameters, the polarization splitter possesses a short length of 890.5 μm, and its wide bandwidth of ˜150 nm almost covers all the S, C, and L communication bands. Besides, it has an excellent electro-interference-resistance property and certain sensitivity to temperature.

  20. Coupled discrete element and smoothed particle hydrodynamics simulations of the die filling process

    NASA Astrophysics Data System (ADS)

    Breinlinger, Thomas; Kraft, Torsten

    2016-11-01

    Die filling is an important part of the powder compaction process chain, where defects in the final part can be introduced—or prevented. Simulation of this process is therefore a goal for many part producers and has been studied by some researchers already. In this work, we focus on the influence of the surrounding air on the powder flow. We demonstrate the implementing and coupling of the discrete element method for the granular powder and the smoothed particle hydrodynamics method for the gas flow. Application of the method to the die filling process is demonstrated.

  1. 30 CFR 816.72 - Disposal of excess spoil: Valley fills/head-of-hollow fills.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., 6-hour precipitation event. (b) Rock-core chimney drains. A rock-core chimney drain may be used in a... as the fill is not located in an area containing intermittent or perennial streams. A rock-core... upstream drainage is diverted around the fill. The alternative rock-core chimney drain system shall...

  2. 30 CFR 816.72 - Disposal of excess spoil: Valley fills/head-of-hollow fills.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., 6-hour precipitation event. (b) Rock-core chimney drains. A rock-core chimney drain may be used in a... as the fill is not located in an area containing intermittent or perennial streams. A rock-core... upstream drainage is diverted around the fill. The alternative rock-core chimney drain system shall...

  3. Intermittent Surface Water Connectivity: Fill and Spill vs. Fill and Merge Dynamics

    EPA Science Inventory

    Intermittent surface connectivity can influence aquatic systems, since chemical and biotic movements are often associated with water flow. Although often referred to as fill and spill, wetlands also fill and merge. We examined the effects of these connection types on water level...

  4. Intermittent surface water connectivity: Fill and spill vs. fill and merge dynamics

    USGS Publications Warehouse

    Leibowitz, Scott G.; Mushet, David M.; Newton, Wesley E.

    2016-01-01

    Intermittent surface connectivity can influence aquatic systems, since chemical and biotic movements are often associated with water flow. Although often referred to as fill and spill, wetlands also fill and merge. We examined the effects of these connection types on water levels, ion concentrations, and biotic communities of eight prairie pothole wetlands between 1979 and 2015. Fill and spill caused pulsed surface water connections that were limited to periods following spring snow melt. In contrast, two wetlands connected through fill and merge experienced a nearly continuous, 20-year surface water connection and had completely coincident water levels. Fill and spill led to minimal convergence in dissolved ions and macroinvertebrate composition, while these constituents converged under fill and merge. The primary factor determining differences in response was duration of the surface water connection between wetland pairs. Our findings suggest that investigations into the effects of intermittent surface water connections should not consider these connections generically, but need to address the specific types of connections. In particular, fill and spill promotes external water exports while fill and merge favors internal storage. The behaviors of such intermittent connections will likely be accentuated under a future with more frequent and severe climate extremes.

  5. High Seebeck Coefficient of Porous Silicon: Study of the Porosity Dependence.

    PubMed

    Valalaki, Katerina; Benech, Philippe; Galiouna Nassiopoulou, Androula

    2016-12-01

    In-plane Seebeck coefficient of porous Si free-standing membranes of different porosities was accurately measured at room temperature. Quasi-steady-state differential Seebeck coefficient method was used for the measurements. A detailed description of our home-built setup is presented. The Seebeck coefficient was proved to increase with increasing porosity up to a maximum of ~1 mV/K for the ~50 % porosity membrane, which is more than a threefold increase compared to the starting highly doped bulk c-Si substrate. By further increasing porosity and after a maximum is reached, the Seebeck coefficient sharply decreases and stabilizes at ~600 μV/K. The possible mechanisms that determine this behaviour are discussed, supported by structural characterization and photoluminescence measurements. The decrease in nanostructure size and increase in carrier depletion with increasing porosity, together with the complex structure and morphology of porous Si, are at the origin of complex energy filtering and phonon drag effects. All the above contribute to the observed anomalous behaviour of thermopower as a function of porosity and will be discussed.

  6. Urban flood modeling using shallow water equations with depth-dependent anisotropic porosity

    NASA Astrophysics Data System (ADS)

    Özgen, Ilhan; Zhao, Jiaheng; Liang, Dongfang; Hinkelmann, Reinhard

    2016-10-01

    The shallow water model with anisotropic porosity conceptually takes into account the unresolved subgrid-scale features, e.g. microtopography or buildings. This enables computationally efficient simulations that can be run on coarser grids, whereas reasonable accuracy is maintained via the introduction of porosity. This article presents a novel numerical model for the depth-averaged equations with anisotropic porosity. The porosity is calculated using the probability mass function of the subgrid-scale features in each cell and updated in each time step. The model is tested in a one-dimensional theoretical benchmark before being evaluated against measurements and high-resolution predictions in three case studies: a dam-break over a triangular bottom sill, a dam-break through an idealized city and a rainfall-runoff event in an idealized urban catchment. The physical processes could be approximated relatively well with the anisotropic porosity shallow water model. The computational resolution influences the porosities calculated at the cell edges and therefore has a large influence on the quality of the solution. The computational time decreased significantly, on average three orders of magnitude, in comparison to the classical high-resolution shallow water model simulation.

  7. Brief communication: Reevaluating osteoporosis in human ribs: the role of intracortical porosity.

    PubMed

    Agnew, Amanda M; Stout, Sam D

    2012-07-01

    Osteoporosis is a major health concern in modern society and is continually being evaluated in past populations by quantifying bone loss. Cortical area measures are commonly used in anthropological analyses to assess bone loss in the ribs, but these values are typically based on endosteal expansion and do not account for intracortical bone loss. The objective of this study is to evaluate the effectiveness of using absolute cortical area, compared to traditional cortical area measures to describe global bone loss in elderly ribs. Transverse sections were prepared from sixth ribs of ten elderly subjects, and bone area measurements were made from 100× magnification composites of each rib for calculation of cortical area (Ct.Ar) and percent cortical area (% C/T). In addition, all areas of intracortical porosity were measured and percent porosity area (% Po.Ar) calculated. Absolute cortical area (Ct.Ar(A)) was calculated by subtracting porosity area from cortical area, and a percent absolute cortical area (% C(A)/T) calculated. ANOVA results reveal significant interindividual variation in percent porosity area (% Po.Ar). Percent cortical area and percent absolute cortical area values were compared and results show a mean difference of 4.08% exists across all subjects, with a range of 1.19-11.73%. This suggests that intracortical porosity is variable and does play a role in age-associated bone loss in the rib. All future investigations of osteoporosis should account for intracortical porosity in bone loss.

  8. On the importance of considering porosity when simulating the fatigue of bone cement.

    PubMed

    Jeffers, Jonathan R T; Browne, Martin; Roques, Anne; Taylor, Mark

    2005-08-01

    Fatigue cracking in the cement mantle of total hip replacement has been identified as a possible cause of implant loosening. Retrieval studies and in vitro tests have found porosity in the cement may facilitate fatigue cracking of the mantle. The fatigue process has been simulated computationally using a finite element/continuum damage mechanics (FE/CDM) method and used as a preclinical testing tool, but has not considered the effects of porosity. In this study, experimental tensile and four-point bend fatigue tests were performed. The tensile fatigue S-N data were used to drive the computational simulation (FE/CDM) of fatigue in finite element models of the tensile and four-point bend specimens. Porosity was simulated in the finite element models according to the theory of elasticity and using Monte Carlo methods. The computational fatigue simulations generated variability in the fatigue life at any given stress level, due to each model having a unique porosity distribution. The fracture site also varied between specimens. Experimental validation was achieved for four-point bend loading, but only when porosity was included. This demonstrates that the computational simulation of fatigue, driven by uniaxial S-N data can be used to simulate nonuniaxial loadcases. Further simulations of bone cement fatigue should include porosity to better represent the realities of experimental models.

  9. Effects of porosity on weld-joint tensile strength of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Lovoy, C. V.

    1974-01-01

    Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

  10. Effect of intragranular porosity on compression behaviour of and drug release from reservoir pellets.

    PubMed

    Tunón, Asa; Gråsjö, Johan; Alderborn, Göran

    2003-08-01

    In this study, reservoir pellets were prepared and their compression behaviour as well as the importance of their porosity for compression-induced changes in drug release was investigated. Pellets of three different porosities, consisting of microcrystalline cellulose and salicylic acid, were prepared by extrusion-spheronisation and spray-coated with ethyl cellulose (ethanol solution). Lubricated reservoir pellets were compressed and retrieved by deaggregation of the tablets. The retrieved pellets were analysed regarding porosity, thickness, surface area, shape and drug release. It was found that the coating did not significantly affect their compression behaviour. Compaction of pellets of high original porosity considerably affected densification and degree of deformation, whereas the effect on drug release was minor. For low porosity pellets the influence of compaction on drug release was appreciable, but only slight regarding densification and degree of deformation. In conclusion, the porosity of pellets is a potential factor that the formulator can use to optimize drug release and one that can affect the robustness of a formulation during manufacture. Moreover, the coating may be able to adapt to the densification and deformation of the pellets.

  11. The effect of grain-coating microquartz on preservation of reservoir porosity

    SciTech Connect

    Aase, M.E.; Bjorkum, P.A.; Nadeau, P.H.

    1996-10-01

    Clay coatings have been widely accepted by many workers as an explanation for preserving high porosity in deeply buried sandstones, but few workers have realized that similar effects can be produced by microcrystalline quartz coatings. This phenomenon can be expected only under special circumstances, but in such cases it can have profound consequences for exploration. In the Central Graben area of the southern North Sea, unusually high porosity (20-27%) and permeability (100-1000 md) are found in certain zones in Upper Jurassic sandstones at depths of 3.4-4.4 km. The porosity in these zones is 5-15% higher than expected based on average porosity-depth trends from Brent and Haltenbanken sandstones. We propose that the high porosity is due to continuous grain coatings of euhedral microcrystalline quartz crystals that are 0.1-2 {mu}m thick. The distribution of microcrystalline quartz coatings is controlled by the presence of siliceous sponge spicules (Rhaxella), which implies a sedimentological control on the reservoir quality. We present a thermodynamic model showing how continuous microcrystalline quartz coatings inhibit development of normal macrocrystalline quartz overgrowths sourced mainly from stylolites. High porosities in parts of various Upper Jurassic oil fields (Ula and Gyda) have previously been explained by inhibition of quartz cementation by early hydrocarbon charge. We suggest that the microcrystalline quartz coatings provide a more plausible explanation.

  12. Porosity measurement of solid pharmaceutical dosage forms by gamma-ray transmission.

    PubMed

    de Oliveira, José Martins; Andréo Filho, Newton; Chaud, Marco Vinícius; Angiolucci, Tatiana; Aranha, Norberto; Martins, Antonio César Germano

    2010-12-01

    The aim of the present work is the determination of porosity in tablets by using the gamma-ray transmission technique. Tablet dissolution depends on some inherent characteristics of the manufacturing process, such as compression force, tablet volume, density and porosity, nature of excipients, preparation methods and its physical-chemical properties. Porosity is a measure of empty spaces in a material and can be determined by various techniques. In this paper, we propose the use of a gamma-ray transmission technique to obtain the porosity of experimental formulation of tablets. The results of porosity were compared with those obtained by using conventional methodology (density and mercury intrusion). The experimental setup for gamma-ray transmission consists of a gamma-ray source of (241)Am (photons of 59.6 keV and an activity of 3.7 × 10(9)Bq), an NaI(Tl) scintillation detector, collimators and a standard gamma-ray spectrometry electronics. Our results suggest that the gamma-ray transmission technique is a powerful tool for non-destructive porosity quantification of solid pharmaceutical forms and presents smaller errors than those obtained with conventional methodologies.

  13. High Seebeck Coefficient of Porous Silicon: Study of the Porosity Dependence

    NASA Astrophysics Data System (ADS)

    Valalaki, Katerina; Benech, Philippe; Galiouna Nassiopoulou, Androula

    2016-04-01

    In-plane Seebeck coefficient of porous Si free-standing membranes of different porosities was accurately measured at room temperature. Quasi-steady-state differential Seebeck coefficient method was used for the measurements. A detailed description of our home-built setup is presented. The Seebeck coefficient was proved to increase with increasing porosity up to a maximum of ~1 mV/K for the ~50 % porosity membrane, which is more than a threefold increase compared to the starting highly doped bulk c-Si substrate. By further increasing porosity and after a maximum is reached, the Seebeck coefficient sharply decreases and stabilizes at ~600 μV/K. The possible mechanisms that determine this behaviour are discussed, supported by structural characterization and photoluminescence measurements. The decrease in nanostructure size and increase in carrier depletion with increasing porosity, together with the complex structure and morphology of porous Si, are at the origin of complex energy filtering and phonon drag effects. All the above contribute to the observed anomalous behaviour of thermopower as a function of porosity and will be discussed.

  14. Phase field crystal study on the grain boundary porosity induced by the Kirkendall effect

    NASA Astrophysics Data System (ADS)

    Lu, Guang-Ming; Lu, Yan-Li; Hu, Ting-Ting; Chen, Zheng

    2016-03-01

    Grain boundary (GB) porosity strongly degrades the bonding quality of interfaces and affects the physical and mechanical properties of solid polycrystalline materials. In this paper, the formation and evolution mechanisms of porosity at the grain boundary were investigated using the binary phase field crystal simulation method. Simulated results indicate that the Kirkendall effect existing in the interdiffusion of substitutional binary alloys can result in GB porosity. For the low-angle grain boundary interdiffusion system, the porosity initially forms at the isolated dislocation core, evolving from circle to irregular polygon. For the large-angle GB interdiffusion system, the porosity initially forms at the dislocation core close to the diffusion plane, and then evolves toward the dislocation cores away from the diffusion plane. The porosities finally connect as a continuous slit that splits up the GB. The results also show that the diffusion of fast diffusers along the GB is obviously enhanced with the mobility ratio of species A and B increasing. Our simulation results agree well with theoretical and experimental results.

  15. Alkaline earth filled nickel skutterudite antimonide thermoelectrics

    DOEpatents

    Singh, David Joseph

    2013-07-16

    A thermoelectric material including a body centered cubic filled skutterudite having the formula A.sub.xFe.sub.yNi.sub.zSb.sub.12, where A is an alkaline earth element, x is no more than approximately 1.0, and the sum of y and z is approximately equal to 4.0. The alkaline earth element includes guest atoms selected from the group consisting of Be, Mb, Ca, Sr, Ba, Ra and combinations thereof. The filled skutterudite is shown to have properties suitable for a wide variety of thermoelectric applications.

  16. Experimental study on capillary filling in nanochannels

    NASA Astrophysics Data System (ADS)

    Yang, Min; Cao, Bing-Yang; Wang, Wei; Yun, He-Ming; Chen, Bao-Ming

    2016-10-01

    We investigated the capillary filling kinetics of deionized water in nanochannels with heights of 50-120 nm. The measured position of the moving meniscus was proportional to the square root of time, as predicted by the LW equation. However, the extracted slopes were significantly smaller than the predictions based on the bulk properties. This unusual behavior was found to be mainly caused by the electro-viscous effect and dynamic contact angle, which was significantly larger than the static angle. In addition, when the filling distance reached about 600 μm, bubbles tended to be formed, leading to the main meniscus was almost immobile.

  17. 62. VIEW LOOKING NORTHWEST AT THE OIL FILLED CIRCUIT BREAKER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    62. VIEW LOOKING NORTHWEST AT THE OIL FILLED CIRCUIT BREAKER FOR GENERATOR NUMBER 1. CIRCUIT BREAKERS ARE AUTOMATED SWITCHES WHICH DISCONNECT THE GENERATORS FROM THE LINE WHEN SHORT CIRCUITS OCCUR. WHEN CIRCUITS INVOLVING HIGH CURRENTS AND VOLTAGES ARE BROKEN, THE AIR SURROUNDING MECHANICAL PARTS OF THE SWITCH BECOMES IONIZED AND CONTINUES TO CONDUCT ELECTRIC POWER ACROSS ANY GAP IN THE SWITCH CONTACTS. TO PREVENT THIS AND INSURE A POSITIVE INTERRUPTION OF CURRENT, THE SWITCH CONTACTS ARE IMMERSED IN A CONTAINER OF OIL. THE OIL DOES NOT SUPPORT THE FORMATION OF AN ARC AND EFFECTIVELY CUTS OFF THE CURRENT WHEN THE SWITCH CONTACTS ARE OPENED. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  18. Characterization of a liquid-filled turbulence simulator

    NASA Astrophysics Data System (ADS)

    Davis, Christopher C.; Zhang, Yimin; Plett, Mark L.; Polak-Dingels, Penelope; Barbier, Pierre R.; Rush, David W.

    1998-10-01

    The development of high performance line-of-sight optical communication links through the turbulent atmosphere is facilitated by laboratory tests of schemes involving adaptive optics, beam tracking, modulation and coding, aperture averaging, fading statistics, and transmitter/receiver diversity. A water-filled turbulence tube has been implemented to simulate, in some respects, the effects produced on a laser beam when it propagates several kilometers through the air. This tube is being used to investigate on a laboratory scale: aperture averaging, fluctuation statistics, optical path difference, high data rate modulation, and various coding schemes. The liquid- filled turbulence tube causes fluctuations on a slower time scale than does the atmosphere. At low turbulence levels it produces log-normal fluctuation statistics, causes tip-tilt errors similar to those previously observed for atmospheric paths, and has already allowed evaluation of aperture averaging and fade statistics. It also allows the testing of various technological schemes to deal with atmospheric turbulence effects without any specific assumptions, such as weak Kolmogorov turbulence, being built into the model.

  19. The efficacy of post porosity plasma protection against vacuum-ultraviolet damage in porous low-k materials

    SciTech Connect

    Lionti, K.; Volksen, W.; Darnon, M.; Magbitang, T.; Dubois, G.

    2015-03-21

    As of today, plasma damage remains as one of the main challenges to the reliable integration of porous low-k materials into microelectronic devices at the most aggressive node. One promising strategy to limit damage of porous low-k materials during plasma processing is an approach we refer to as post porosity plasma protection (P4). In this approach, the pores of the low-k material are filled with a sacrificial agent prior to any plasma treatment, greatly minimizing the total damage by limiting the physical interactions between plasma species and the low-k material. Interestingly, the contribution of the individual plasma species to the total plasma damage is not fully understood. In this study, we investigated the specific damaging effect of vacuum-ultraviolet (v-UV) photons on a highly porous, k = 2.0 low-k material and we assessed the P4 protective effect against them. It was found that the impact of the v-UV radiation varied depending upon the v-UV emission lines of the plasma. More importantly, we successfully demonstrated that the P4 process provides excellent protection against v-UV damage.

  20. The structure of filled skutterudites and the local vibration behavior of the filling atom

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaojuan; Zong, Peng-an; Chen, Xihong; Tao, Juzhou; Lin, He

    2017-02-01

    Both of atomic pair distribution function (PDF) and extended x-ray absorption fine structure (EXAFS) experiments have been carried out on unfilled and Yb-filled skutterudites YbxCo4Sb12 (x=0, 0.15, 0.2 and 0.25) samples. The structure refinements on PDF data confirm the large amplitude vibration of Yb atom and the dependence of Yb vibration amplitude on the filling content. Temperature dependent EXAFS experiment on filled skutterudites have been carried out at Yb LⅢ-edge in order to explore the local vibration behavior of filled atom. EXAFS experiments show that the Einstein temperature of the filled atom is very low (70.9 K) which agrees with the rattling behavior.

  1. Enhancing Performance of Triboelectric Nanogenerator by Filling High Dielectric Nanoparticles into Sponge PDMS Film.

    PubMed

    Chen, Jie; Guo, Hengyu; He, Xianming; Liu, Guanlin; Xi, Yi; Shi, Haofei; Hu, Chenguo

    2016-01-13

    Understanding of the triboelectric charge accumulation from the view of materials plays a critical role in enhancing the output performance of triboelectric nanogenerator (TENG). In this paper, we have designed a feasible approach to modify the tribo-material of TENG by filling it with high permittivity nanoparticles and forming pores. The influence of dielectricity and porosity on the output performance is discussed experimentally and theoretically, which indicates that both the surface charge density and the charge transfer quantity have a close relationship with the relative permittivity and porosity of the tribo-material. A high output performance TENG based on a composite sponge PDMS film (CS-TENG) is fabricated by optimizing both the dielectric properties and the porosity of the tribo-material. With the combination of the enhancement of permittivity and production of pores in the PDMS film, the charge density of ∼19 nC cm(-2), open-circuit voltage of 338 V, and power density of 6.47 W m(-2) are obtained at working frequency of 2.5 Hz with the optimized film consisting of 10% SrTiO3 nanoparticles (∼100 nm in size) and 15% pores in volume, which gives over 5-fold power enhancement compared with the nanogenerator based on the pure PDMS film. This work gives a better understanding of the triboelectricity produced by the TENG from the view of materials and provides a new and effective way to enhance the performance of TENG from the material itself, not just its surface modification.

  2. Simultaneous measurement of temperature and force with high sensitivities based on filling different index liquids into photonic crystal fiber.

    PubMed

    Liang, Hu; Zhang, Weigang; Geng, Pengcheng; Liu, Yange; Wang, Zhi; Guo, Junqi; Gao, Shecheng; Yan, Suyuan

    2013-04-01

    A double-filled photonic crystal fiber (PCF) was fabricated by filling liquids of different indexes into two air holes in the cladding. The core mode coupled to the local cladding modes LP(01) and LP(11) in the 1310 and 1550 nm wavebands, respectively. Due to the unique characteristics of the mode coupling, the resonant peaks in different resonance areas shifted to the opposite directions with the variations of the temperature or the force. The double-filled PCFs achieved in this work showed useful applications in the simultaneous measurement of both the temperature and the force.

  3. Lithology, porosity and morphology influence on temperate low- and mid-altitudes cold screes susceptible to host permafrost

    NASA Astrophysics Data System (ADS)

    Popescu, Razvan; Vespremeanu-Stroe, Alfred; Alexandru, Onaca; Cruceru, Nicolae

    2015-04-01

    The ventilated cold screes from the temperate regions develop high negative thermal anomalies (ground versus air annual temperature) in their lower parts due to cold air aspiration in wintertime, which support the formation of cold reservoirs and sometimes of the perennial frozen ground. Ground and air temperature monitoring, geophysical soundings, debris texture and porosity measurements and dendrogeomorphological analyses were applied at Detunata sites in Apuseni Mts (Western Romanian Carpathians) to investigate a low-altitude cold scree (ca. 1080 m) accommodated in basalt debris. The large negative anomalies (6 - 6.8 °C), the high resistivity values (up to 65 kΩm) recorded in late spring and mid-autumn and the dwarf forest occurrence (whose growth rates are ca. 3 times smaller than the common forest) support the permafrost presence. The new results were integrated into an inter-site evaluation based on the internationally reported cold screes which reveals the priority of lithology in controlling their thermal behavior and implicitly the cold reservoir formation or even permafrost into low- and mid-altitude cold screes. As long as the mean slope of debris exceeds a critical threshold (25°), the exceptional high porosity is the driving factor for an extensive and intensified chimney circulation responsible for the overcooling of the winter aspiration zone normally placed on the slope bottoms and on the negative features (depressions, furrows) in case of rock glacier - talus slope morphology. Lithology assessment highlights that most of the cold screes (ca. 2/3) are composed by only two rock types: basalts and limestones. The poor thermal-conductive basalts which built the most porous screes show the highest negative offsets (6 - 9 °C), which recommend them as the optimum rock type for the low-altitude permafrost sites (< 1200 m) and stands for more than ¾ of the cold screes. Limestone is a preferred accommodation for the mid-altitude permafrost sites (1200

  4. The impact of porosity waves on crustal reaction progress and CO2 mass transfer

    NASA Astrophysics Data System (ADS)

    Tian, Meng; Ague, Jay J.

    2014-03-01

    Rocks below the brittle-ductile transition can deform viscously and compact while fluid percolates through (two-phase solid-fluid flow). We investigate chemical reaction systematics during two-phase flow using one-dimensional numerical models in which reactive H2O-CO2 fluid ascends down-temperature toward the surface, driving the retrograde reaction: 7CO2+3Calcite+Tremolite=5Dolomite+8Quartz+H2O. The reaction progress is compared to that predicted by fluid-rock reaction during “standard” Darcian flow. A range of layer thicknesses (km-scale) in one- and two-layer systems were investigated at pressure-temperature conditions below the brittle-ductile transition corresponding to ∼13-20 km depth. Model porosity waves of wavelength ∼5 km were generated repeatedly at the base of the flow region using a solitary wave solution with a prescribed initial wave amplitude A = (maximum porosity)/(background porosity of 10-3). Simulation of reaction progress and carbon transfer for the Darcian flow model and for porosity wave transport with A=5, 2.5 and 1.25 yield the following results. First, the overall reaction progress in the two fluid transport models is mainly controlled by the time-integrated fluid flux, and is not strongly dependent on the flow regime. The implication is that the fluid pressure gradient anomalies in the regional-scale porosity waves modeled herein play a negligible role in driving reaction progress. Second, although there are high fluid velocities and thus strong advection in large amplitude porosity waves, the kinetic parameters adopted from experiments predict that the fluid compositions approach local fluid-rock equilibrium in both transport models. Third, regional-scale carbonate-bearing rock layers may be substantial sinks for carbon in ascending fluids if sufficient porosity and permeability can be maintained during reaction. Finally, typical models of retrograde reactions predict that porosity ultimately becomes clogged and, thus, fluid flow

  5. Meteoric calcite cementation: diagenetic response to relative fall in sea-level and effect on porosity and permeability, Las Negras area, southeastern Spain

    NASA Astrophysics Data System (ADS)

    Li, Zhaoqi; Goldstein, Robert H.; Franseen, Evan K.

    2017-03-01

    A dolomitized Upper Miocene carbonate system in southeast Spain contains extensive upper and lower zones of calcite cementation that cut across the stratigraphy. Cement textures including isopachous and circumgranular, which are consistent with phreatic-zone cementation. Cements in the upper cemented zone are non-luminescent, whereas those in the lower cemented zone exhibit multiple bands of luminescent and non-luminescent cements. In the upper cemented zone, isotopic data show two meteoric calcite lines (MCL) with mean δ18O at - 5.1‰ and - 5.8‰ VPDB, whereas no clear MCL is defined in the lower cemented zone where mean δ18O for calcite cement is at - 6.7‰ VPDB. δ13C values in both cement zones are predominantly negative, ranging from - 10 to + 2‰ VPDB, suggestive of carbon from soil gas or decayed organics. Measurements of Tm ice in primary fluid inclusions yield a mode of 0.0 °C in both zones, indicating calcite cementation from fresh water. These two zones define the positions of two different paleo-water tables that formed during a relative sea-level fall and erosional downcutting during the Plio-Pleistocene. The upper cemented zone pre-dated the lower cemented zone on the basis of known relative sea-level history. Meteoric calcite cementation reduced porosity and permeability, but measured values are inconsistent with simple filling of open pore space. Each texture, boundstone, grainstone, packstone, wackestone, produces a different relationship between percent calcite cement and porosity/permeability. Distribution of cements may be predictable on the basis of known sea-level history, and the effect of the cementation can be incorporated into subsurface geomodels by defining surfaces of rock boundaries that separate cemented zones from uncemented zones, and applying texture-specific relationships among cementation, porosity and permeability.

  6. Cotton-Fiber-Filled Rubber Insulation

    NASA Technical Reports Server (NTRS)

    Anderson, Floyd A.

    1987-01-01

    Carbonization of fibers at high temperatures improves strength and erosion resistance. Cotton linters tested as replacement for asbestos filler currently used in rubber insulation in solid rocket motors. Cotton-filled rubber insulation has industrial uses; in some kinds of chemical- or metal-processing equipment, hoses, and protective clothing.

  7. 7 CFR 58.730 - Filling containers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Procedures § 58.730 Filling containers. Hot fluid cheese from the cookers may be held in hotwells or hoppers to assure a constant and even supply of processed cheese to the filler or slice former. Filler valves... and shall cut off sharply without drip or drag of cheese across the opening. An effective system...

  8. Banach spaces that realize minimal fillings

    NASA Astrophysics Data System (ADS)

    Bednov, B. B.; Borodin, P. A.

    2014-04-01

    It is proved that a real Banach space realizes minimal fillings for all its finite subsets (a shortest network spanning a fixed finite subset always exists and has the minimum possible length) if and only if it is a predual of L_1. The spaces L_1 are characterized in terms of Steiner points (medians). Bibliography: 25 titles.

  9. Irregularly Shaped Space-Filling Truncated Octahedra

    ERIC Educational Resources Information Center

    Hanson, John Robert

    2008-01-01

    For any parent tetrahedron ABCD, centroids of selected sub-tetrahedra form the vertices of an irregularly shaped space-filling truncated octahedron. To reflect these properties, such a figure will be called an ISTO. Each edge of the ISTO is parallel to and one-eighth the length of one of the edges of tetrahedron ABCD and the volume of the ISTO is…

  10. The Chemistry of Modern Dental Filling Materials.

    ERIC Educational Resources Information Center

    Nicholson, John W.; Anstice, H. Mary

    1999-01-01

    Discusses materials used by dentists to restore teeth after decay has been removed. Shows how dental-material science is an interdisciplinary field in which chemistry plays a major part. Reviews the many developments polymer chemistry has contributed to the field of dental fillings. (CCM)

  11. SOIL AND FILL LABORATORY SUPPORT - 1991

    EPA Science Inventory

    The report gives results of soil analysis laboratory work by the University of Florida in Support of the Florida Radon Research Program (FRRP). Analyses were performed on soil and fill samples collected during 1991 by the FRRP Research House program and the New House Evaluation P...

  12. Banach spaces that realize minimal fillings

    SciTech Connect

    Bednov, B. B.; Borodin, P. A. E-mail: pborodin@inbox.ru

    2014-04-30

    It is proved that a real Banach space realizes minimal fillings for all its finite subsets (a shortest network spanning a fixed finite subset always exists and has the minimum possible length) if and only if it is a predual of L{sub 1}. The spaces L{sub 1} are characterized in terms of Steiner points (medians). Bibliography: 25 titles. (paper)

  13. 5 CFR 362.203 - Filling positions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... applications from individuals outside its own workforce, it must provide OPM information concerning... position, and (iii) How to apply. A public source (e.g., a link to the agency's Web site with information... subject-matter expertise, or to fill traditional summer jobs. The agency may extend these...

  14. 5 CFR 362.203 - Filling positions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... applications from individuals outside its own workforce, it must provide OPM information concerning... position, and (iii) How to apply. A public source (e.g., a link to the agency's Web site with information... subject-matter expertise, or to fill traditional summer jobs. The agency may extend these...

  15. Biomineral nanoparticles are space-filling

    NASA Astrophysics Data System (ADS)

    Yang, Li; Killian, Christopher E.; Kunz, Martin; Tamura, Nobumichi; Gilbert, P. U. P. A.

    2011-02-01

    Sea urchin biominerals have been shown to form from aggregating nanoparticles of amorphous calcium carbonate (ACC), which then crystallize into macroscopic single crystals of calcite. Here we measure the surface areas of these biominerals and find them to be comparable to those of space-filling macroscopic geologic calcite crystals. These biominerals differ from synthetic mesocrystals, which are invariably porous. We propose that space-filling ACC is the structural precursor for echinoderm biominerals.Sea urchin biominerals have been shown to form from aggregating nanoparticles of amorphous calcium carbonate (ACC), which then crystallize into macroscopic single crystals of calcite. Here we measure the surface areas of these biominerals and find them to be comparable to those of space-filling macroscopic geologic calcite crystals. These biominerals differ from synthetic mesocrystals, which are invariably porous. We propose that space-filling ACC is the structural precursor for echinoderm biominerals. This article was submitted as part of a Themed Issue on Crystallization and Formation Mechanisms of Nanostructures. Other papers on this topic can be found in issue 11 of vol. 2 (2010). This issue can be found from the Nanoscale homepage [http://www.rsc.org/nanoscale

  16. Thermotropic nematic order upon nanocapillary filling

    NASA Astrophysics Data System (ADS)

    Huber, Patrick; Busch, Mark; Całus, Sylwia; Kityk, Andriy V.

    2013-04-01

    Optical birefringence and light absorption measurements reveal four regimes for the thermotropic behavior of a nematogen liquid (7CB) upon sequential filling of parallel-aligned capillaries of 12 nm diameter in a monolithic, mesoporous silica membrane. No molecular reorientation is observed for the first adsorbed monolayer. In the film-condensed state (up to 1 nm thickness), a weak, continuous paranematic-to-nematic (P-N) transition is found, which is shifted by 10 K below the discontinuous bulk transition at TIN=305 K. The capillary-condensed state exhibits a more pronounced, albeit still continuous P-N reordering, located 4 K below TIN. This shift vanishes abruptly upon complete filling of the capillaries. It could originate in competing anchoring conditions at the free inner surfaces and at the pore walls or result from the 10-MPa tensile pressure release associated with the disappearance of concave menisci in the confined liquid upon complete filling. The study documents that the thermo-optical properties of nanoporous systems (or single nanocapillaries) can be tailored over a surprisingly wide range simply by variation of the filling fraction with liquid crystals.

  17. New Skeletal-Space-Filling Models

    ERIC Educational Resources Information Center

    Clarke, Frank H.

    1977-01-01

    Describes plastic, skeletal molecular models that are color-coded and can illustrate both the conformation and overall shape of small molecules. They can also be converted to space-filling counterparts by the additions of color-coded polystyrene spheres. (MLH)

  18. Postscript: Filling-in Models of Completion

    ERIC Educational Resources Information Center

    Anderson, Barton L.

    2007-01-01

    Presents some additional comments from the current author regarding his original article "Filling-in models of completion: Rejoinder to Kellman, Garrigan, Shipley, and Keane (2007) and Albert (2007)." Despite repeated assertions by Kellman et al., I have never claimed that luminance constraints block modal completion; rather, they merely weaken…

  19. 27 CFR 19.360 - Filling packages.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Filling packages. 19.360 Section 19.360 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for...

  20. 27 CFR 19.390 - Filling packages.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Filling packages. 19.390 Section 19.390 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Processing Operations Other Than Denaturation...

  1. 27 CFR 19.360 - Filling packages.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Filling packages. 19.360 Section 19.360 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for...

  2. 27 CFR 19.360 - Filling packages.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Filling packages. 19.360 Section 19.360 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for...

  3. 27 CFR 19.360 - Filling packages.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Filling packages. 19.360 Section 19.360 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for...

  4. Protecting tree roots and subterranean infrastructure in urban areas by developing self-compacting flowable fills with root growth impeding properties

    NASA Astrophysics Data System (ADS)

    Felde, Vincent; Simon, Jana; Kimm-Friedenberg, Stefan; Peth, Stephan; Middendorf, Bernhard

    2015-04-01

    In urban areas, the installation of cables and disposal lines is still done by open building method. Here, a ditch is being excavated, pipes and lines are laid and subsequently it is filled with and covered by bulk material (e.g. sand or gravel), which is then compacted. Due to the often times limited space that the roots have in the ground and the better supply of water and oxygen in the poorly compacted bulk material, these refilled ditches are areas of preferential root growth of urban trees. The entangling of the pipes and supply lines by these roots leads to severe damage of the tree when maintenance work on the lines is carried out and roots have to be cut. In order to reduce this competition between urban trees and urban subterranean infrastructure, the development of a self-compacting flowable fill with root growth resistance is mandatory. Physico-chemical properties, such as a very high pH-value and a low cation-exchange-capacity, a low root-penetrability, a high packing density and a low porosity, with a poorly connected pore system that impedes gas and water exchange are the characteristic aspects of this flowable fills that could help avoid undesired root penetration into supply lines. The flowable fills are supposed to sheath pipes and lines void-free and without any tension, in order to restrain the root growth in these areas. Trees are of crucial importance for urban ecosystems and are comprising 3% of the total stock of trees in the Federal Republic of Germany, which is why it is fundamental to conserve them. This work therefore targets not only at enabling a balanced coexistence of urban trees and subterranean infrastructure, but also at avoiding costly re-opening of ditches, tree harming cutting of roots and time consuming maintenance work. Further positive side effects are reduced costs for network providers and local municipalities, as well as reduced noise and dust emissions for passersby and local residents. To guarantee the root growth

  5. Porosity and biocompatibility study of ceramic implants based on ZrO{sub 2} and Al{sub 2}O{sub 3}

    SciTech Connect

    Litvinova, Larisa E-mail: vshupletsova@mail.ru Shupletsova, Valeria E-mail: vshupletsova@mail.ru Leitsin, Vladimir E-mail: vshupletsova@mail.ru; Vasyliev, Roman E-mail: zoubov77@yahoo.com; Zubov, Dmitry E-mail: zoubov77@yahoo.com; Buyakov, Ales E-mail: kulkov@ms.tsc.ru; Kulkov, Sergey E-mail: kulkov@ms.tsc.ru

    2014-11-14

    The work studies ZrO{sub 2}(Me{sub x}O{sub y})-based porous ceramics produced from the powders consisting of hollow spherical particles. It was shown that the structure is represented by a cellular framework with bimodal porosity consisting of sphere-like large pores and pores that were not filled with the powder particles during the compaction. For such ceramics, the increase of pore volume is accompanied by the increased strain in an elastic area. It was also shown that the porous ZrO{sub 2} ceramics had no acute or chronic cytotoxicity. At the same time, ceramics possess the following osteoconductive properties: adhesion support, spreading, proliferation and osteogenic differentiation of MSCs.

  6. Relationship between compressional-wave velocity and porosity of sediments along subduction plate interface

    NASA Astrophysics Data System (ADS)

    Yamaguchi, M.; Hashimoto, Y.

    2012-12-01

    Evolution of physical properties of sediments along subduction interface has effects on wedge strength, wedge geometry, dewatering and dehydration processes, and seismic behavior. Sediments have initially more than 70% of porosity prior to subduction. Through underthrusting and accretion, porosity of sediments decreases by compaction and cementation to be lithified sediments. The purpose of this study is to understand evolution of physical properties from a state before subduction to a state within a wedge using a relationship between compressional-wave velocity and porosity. In this study, we obtained new data for sediments from a reference site in IODP NanTroSEIZE, Expedition 333. In addition to that, we have complied velocity-porosity relationships for the samples and also for previous studies from NanTroSEIZE (off Kumano) (Hashimoto et al., 2010, 2011), ODP Leg 190 (off Shikoku) (Hoffman and Tobin, 2004) and ODP Leg 170 (off Costa Rica) (Gettemy and Tobin, 2003). Velocity measurement procedure in this study to obtain new data is as following: Two pumps were used to control pore fluid pressure and confining pressure. The pore pressure of 1000kPa was kept under drained conditions. Confining (effective) pressure was increased stepwise in the measurements. Velocity measurements were conducted under isotropic pressure conditions. Confining pressure was pressurized in tens seconds and kept for more than 8 hours for next step to obtain equilibrium conditions between effective pressure and sediments strain. Lead zirconate titanate (PZT) shear wave transducers (500kHz) were used in a source-receiver pair to measure wave speed. Porosity and P-wave velocity ranges about 27 - 75% and 1.4 - 2.2 km/s in this study, respectively. In the comparison in Vp-porosity relationships between sedimetns from reference sites and others, sediments were classified into two, simply compacted sediments (reference site and slope sediments) and wedge sediments. Different trends in Vp-porosity

  7. Porosity variations in and around normal fault zones: implications for fault seal and geomechanics

    NASA Astrophysics Data System (ADS)

    Healy, David; Neilson, Joyce; Farrell, Natalie; Timms, Nick; Wilson, Moyra

    2015-04-01

    Porosity forms the building blocks for permeability, exerts a significant influence on the acoustic response of rocks to elastic waves, and fundamentally influences rock strength. And yet, published studies of porosity around fault zones or in faulted rock are relatively rare, and are hugely dominated by those of fault zone permeability. We present new data from detailed studies of porosity variations around normal faults in sandstone and limestone. We have developed an integrated approach to porosity characterisation in faulted rock exploiting different techniques to understand variations in the data. From systematic samples taken across exposed normal faults in limestone (Malta) and sandstone (Scotland), we combine digital image analysis on thin sections (optical and electron microscopy), core plug analysis (He porosimetry) and mercury injection capillary pressures (MICP). Our sampling includes representative material from undeformed protoliths and fault rocks from the footwall and hanging wall. Fault-related porosity can produce anisotropic permeability with a 'fast' direction parallel to the slip vector in a sandstone-hosted normal fault. Undeformed sandstones in the same unit exhibit maximum permeability in a sub-horizontal direction parallel to lamination in dune-bedded sandstones. Fault-related deformation produces anisotropic pores and pore networks with long axes aligned sub-vertically and this controls the permeability anisotropy, even under confining pressures up to 100 MPa. Fault-related porosity also has interesting consequences for the elastic properties and velocity structure of normal fault zones. Relationships between texture, pore type and acoustic velocity have been well documented in undeformed limestone. We have extended this work to include the effects of faulting on carbonate textures, pore types and P- and S-wave velocities (Vp, Vs) using a suite of normal fault zones in Malta, with displacements ranging from 0.5 to 90 m. Our results show a

  8. Numerical recipes for mold filling simulation

    SciTech Connect

    Kothe, D.; Juric, D.; Lam, K.; Lally, B.

    1998-07-01

    Has the ability to simulate the filling of a mold progressed to a point where an appropriate numerical recipe achieves the desired results? If results are defined to be topological robustness, computational efficiency, quantitative accuracy, and predictability, all within a computational domain that faithfully represents complex three-dimensional foundry molds, then the answer unfortunately remains no. Significant interfacial flow algorithm developments have occurred over the last decade, however, that could bring this answer closer to maybe. These developments have been both evolutionary and revolutionary, will continue to transpire for the near future. Might they become useful numerical recipes for mold filling simulations? Quite possibly. Recent progress in algorithms for interface kinematics and dynamics, linear solution methods, computer science issues such as parallelization and object-oriented programming, high resolution Navier-Stokes (NS) solution methods, and unstructured mesh techniques, must all be pursued as possible paths toward higher fidelity mold filling simulations. A detailed exposition of these algorithmic developments is beyond the scope of this paper, hence the authors choose to focus here exclusively on algorithms for interface kinematics. These interface tracking algorithms are designed to model the movement of interfaces relative to a reference frame such as a fixed mesh. Current interface tracking algorithm choices are numerous, so is any one best suited for mold filling simulation? Although a clear winner is not (yet) apparent, pros and cons are given in the following brief, critical review. Highlighted are those outstanding interface tracking algorithm issues the authors feel can hamper the reliable modeling of today`s foundry mold filling processes.

  9. Laser-filamentation-induced water condensation and snow formation in a cloud chamber filled with different ambient gases.

    PubMed

    Liu, Yonghong; Sun, Haiyi; Liu, Jiansheng; Liang, Hong; Ju, Jingjing; Wang, Tiejun; Tian, Ye; Wang, Cheng; Liu, Yi; Chin, See Leang; Li, Ruxin

    2016-04-04

    We investigated femtosecond laser-filamentation-induced airflow, water condensation and snow formation in a cloud chamber filled respectively with air, argon and helium. The mass of snow induced by laser filaments was found being the maximum when the chamber was filled with argon, followed by air and being the minimum with helium. We also discussed the mechanisms of water condensation in different gases. The results show that filaments with higher laser absorption efficiency, which result in higher plasma density, are beneficial for triggering intense airflow and thus more water condensation and precipitation.

  10. Filling the blanks in temporal intervals: the type of filling influences perceived duration and discrimination performance

    PubMed Central

    Horr, Ninja K.; Di Luca, Massimiliano

    2015-01-01

    In this work we investigate how judgments of perceived duration are influenced by the properties of the signals that define the intervals. Participants compared two auditory intervals that could be any combination of the following four types: intervals filled with continuous tones (filled intervals), intervals filled with regularly-timed short tones (isochronous intervals), intervals filled with irregularly-timed short tones (anisochronous intervals), and intervals demarcated by two short tones (empty intervals). Results indicate that the type of intervals to be compared affects discrimination performance and induces distortions in perceived duration. In particular, we find that duration judgments are most precise when comparing two isochronous and two continuous intervals, while the comparison of two anisochronous intervals leads to the worst performance. Moreover, we determined that the magnitude of the distortions in perceived duration (an effect akin to the filled duration illusion) is higher for tone sequences (no matter whether isochronous or anisochronous) than for continuous tones. Further analysis of how duration distortions depend on the type of filling suggests that distortions are not only due to the perceived duration of the two individual intervals, but they may also be due to the comparison of two different filling types. PMID:25717310

  11. Pore-filling cements in turbidites; Southern California: Products of early diagenesis and dewatering of shale

    NASA Astrophysics Data System (ADS)

    Krystinik, L. F.

    Cementation of deep sea fan deposits which begins at the sediment water interface and continues progressively to the maximum depths was studied. The type and intensity of cementation is determined, in part, by the labile components within the system. Authigenic iron-rich smectite (AIRS) is the earliest cement in deep sea sediment. Formation of AIRS begins with the dissolution of biogenic silica. The Stevens sand provides insight into the early stages of graywacke formation. A significant volume of nondetrital, nonpseudomatrix clay is generated by precipitation of dissolved species carried into a sandstone body by waters expelled from adjacent shale. The Stevens also provides insight into turbidite sedimentation within a restricted basin supplied by several sediment sources. Most Cenozoic turbidities from southern California contain either calcite cement which occludes porosity and preserves the initial character of the sediment, or a silica clay cement which reduces porosity slightly, but occludes permeability. Cementation of sandstones by clays precipitated from pore fluids generated in adjacent shales may be a first step toward the genesis of graywacke.

  12. Secondary porosity and permeability of coal vs. gas composition and pressure

    SciTech Connect

    Mavor, M.J,; Gunter, W.D.

    2006-04-15

    We have been investigating the sequestration of atmospheric pollutants by injection into coal seams while at the same time enhancing hydrocarbon productivity by displacement of methane with pollutants. We found that changing the composition of the gas sorbed into the coal changes the porosity and permeability of the coal natural-fracture system owing to gas-content changes, which cause matrix swelling or shrinkage due to relative adsorption of different gases. We collected sufficient information to develop a method for predicting the permeability and porosity of a coalbed as a function of the secondary porosity system (SPS) pressure and the gas content and composition of the primary porosity system (PPS). The method uses data from injection/falloff tests with water and/or a weaker adsorbing gas (WAG) than CH{sub 4} and a stronger adsorbing gas (SAG) than CH{sub 4}. Estimates of effective permeability to gas and water obtained from these tests are used with an iterative computation procedure subject to constraints to solve for equivalent SPS porosity and absolute permeability at atmospheric pressure. Once calibrated, the model can be used to predict a coalbed's permeability and porosity as a function of injection pressure and injected-fluid composition, which in turn are used to predict injection performance. The model is applicable to production forecasts to account for SPS permeability and porosity changes as reservoir pressure declines with changes in gas composition. This paper describes the new model and discusses well-test procedures to obtain the data required for model calibration. Also included are coal property estimates resulting from Alberta Medicine River (Manville) coal core and test data and an example model calibration.

  13. Early Cambrian Relief Sandstone, Officer basin, south Australia - An example of secondary porosity development

    SciTech Connect

    Gaugham, C.J.; Warren, J.K. )

    1990-05-01

    The Lower Cambrian Relief Sandstone has been drilled and cored at seven locations in the eastern Officer basin, central Australia. Core, well log, petrographic, and x-ray diffraction analyses have been used to subdivide the Relief Sandstone into stratigraphic units and individual depositional environments, and to determined controlling factors on known reservoir distribution and quality. Interest in the Relief Sandstone as a potential economic oil-bearing sandstone is supported by excellent reservoir quality (up to 26.5% porosity and 4,839 md permeability). Potential source rocks are found above, below and interfingering with the Relief Sandstone. There are several occurrences of live oil bleeding from vugs and fractures in a stratigraphically higher carbonate. Traces of oil in the Relief sands and the presence of live oil in relatively close proximity suggests that the Relief Sandstone could host an economic oil accumulation. The majority of the Relief Sandstone was deposited in eolian or braided fluvial environments, with some alluvial fan sedimentation in the east, and tidal- to shallow-marine deposition in the west. Distribution of reservoir-quality sands is bimodal. In the east porosity and permeability for the most part are very poor to average. In the west, porosity and permeability are generally good to excellent. The bulk of the economic porosity is secondary, a result of dissolution of cement and matrix, with minor porosity from leaching of grains. The lower reservoir quality in the east is due to diagenesis associated with compaction and authigenic illite. Grain packing with suturing and silica overgrowths have reduced primary porosity to noneconomic levels. Permeability has been reduced by these processes and by the blocking of pore throats with authigenic illite. In the west, the porosity and permeability are high and generally due to dissolution of clay cement and primary matrix.

  14. Depositional environments, diagenetic history, and porosity development, vacuum San Andres Field, Lea County, New Mexico

    SciTech Connect

    Robertson, J.W. )

    1990-02-01

    The Permian San Andres Formation was deposited in environments ranging from supratidal to subtidal, protected shallow marine to open shallow marine. Pelletoid-skeletal packstone/wackestone and pelletoid-oolite-skeletal packstone/grainstone facies of the composite subtidal, marine environments were concentrated in the southern half of the field where grainstone deposition was linked to a paleotopographic high. Deposition in the northern half of the field was dominated by the pelletoid wackestone/mudstone facies of the supratidal, restricted shallow-marine environment. Porosity is mainly diagenetic in origin. San Andres rocks passed through the marine phreatic, the mixed phreatic, the meteoric phreatic, and the deeper subsurface diagenetic environments. Matrix dolomitization in the marine and mixed-phreatic environment produced intercrystalline porosity in all the facies. Leaching of nondolomitized grains in the mixed phreatic and meteoric-phreatic environments created large moldic pores. Diagenetic patterns follow structural and depositional trends so that suites of characteristic pore types exist for each facies. Individual pore types consist of moldic, intergranular, intragranular, vuggy, and intercrystalline categories. Intercrystalline pores are present nearly everywhere, and predicting the abundance of moldic pores is the largest variable in predicting porosity values for a given stratigraphic interval. Highest porosity exists in the southern half of the study area where grainier facies were deposited on a paleotopographic high, and grains were partly dolomitized and subsequently were removed by leaching, leaving behind a composite intercrystalline-moldic pore network. Total porosity values do not correspond with facies boundaries, so porosity mapping was accomplished by dividing the San Andres into 20-ft-thick slices and computer contouring total porosity greater than 6% in each slice.

  15. Numerical study of sidewall filling for gas-fed pulse detonation engines

    NASA Astrophysics Data System (ADS)

    Rongrat, Wunnarat

    Pulse detonation engines for aerospace propulsion are required to operate at 50-100 Hz meaning that each pulse is 10-20 ms long. Filling of the engine and the related purging process become dominant due to their long duration compared to ignition and detonation wave propagation. This study uses ANSYS FLUENT to investigate the filling of a 1 m long tube with an internal diameter of 100 mm. Six different configurations were investigated with an endwall port and various sidewall arrangements, including stagger and inclination. A stoichiometric mixture of gaseous octane and air at STP was used to fill the tube at injection rates of 40, 150 and 250 m/s. Phase injection was also investigated and it showed performance improvements such as reduced lling time and reduced propellant escape from the exit.

  16. Air-coupled ultrasonic spectroscopy applied to the study of the properties of paper produced from mineral powder (mineral paper).

    NASA Astrophysics Data System (ADS)

    Soto, D. A.; Salas, R. A.; Alvarez-Arenas, T. E. Gómez

    2012-05-01

    A recent technology has been introduced into the paper industry that makes possible to produce paper materials by replacing the cellulose fibres by a mineral powder, achieving a more environmentally friendly product compared with conventional paper. The purpose of this work is to determine the possibilities of an air-coupled ultrasonic technique to study this kind of new materials in order to develop an ultrasonic system useful for quality control for this industry. In particular, air-coupled ultrasonic spectroscopy is specially well suited to this kind of materials because of the fact that no coupling liquid and no direct contact with the sample is employed. A through transmission technique is employed and Fourier analysis is performed to obtain both magnitude and phase spectra of the transmission coefficient. Properties in the thickness direction as well as in the paper plane are investigated. Different paper grades (from 120 to 400 g/m2) provided by Terraskin have been studied. Very high attenuation coeficientes and very low propagation velocities (and hence elastic constant) are obtained, this can be explained by considering the large porosity of this material (about 50%) and the microstrucutre: solid grains in contact with a variable amount of polymeric resin partially filling the pore space.

  17. SEMICONDUCTOR TECHNOLOGY Dummy fill effect on CMP planarity

    NASA Astrophysics Data System (ADS)

    Junxiong, Zhou; Lan, Chen; Wenbiao, Ruan; Zhigang, Li; Weixiang, Shen; Tianchun, Ye

    2010-10-01

    With the use of a chemical-mechanical polishing (CMP) simulator verified by testing data from a foundry, the effect of dummy fill characteristics, such as fill size, fill density and fill shape, on CMP planarity is analyzed. The results indicate that dummy density has a significant impact on oxide erosion, and copper dishing is in proportion to dummy size. We also demonstrate that cross shape dummy fill can have the best dishing performance at the same density.

  18. Determination of Granites' Mineral Specific Porosities by PMMA Method and FESEM/EDAX

    SciTech Connect

    Leskinen, A.; Penttinen, L.; Siitari-Kauppi, M.; Alanso, U.; Garcia-Gutierrez, M.; Missana, T.; Patelli, Alessandro

    2007-07-01

    Over extended periods, long-lived radionuclides (RN) or activation products within geologic disposal sites may be released from the fuel and migrate to the geo/biosphere. In the bedrock, contaminants will be transported along fractures by advection and retarded by sorption on mineral surfaces and by molecular diffusion into stagnant pore water in the matrix along a connected system of pores and micro-fissures. The objective of this paper was to determine the connective porosity and mineral-specific porosities for three granite samples by {sup 14}C methyl-methacrylate ({sup 14}C-PMMA) autoradiography. Scanning electron microscopy and energy-dispersive X-ray analyses (FESEM/EDAX) were performed in order to study the pore apertures of porous regions in greater detail and to identify the corresponding minerals. Finally, the porosity results were used to evaluate the diffusion coefficients of RNs from previous experiments which determined apparent diffusion coefficients for the main minerals in three granite samples by the Rutherford Backscattering technique. The total porosity of the Grimsel granite (0.75%) was significantly higher than the porosities of the El Berrocal and Los Ratones granites (0.3%). The porosities of the Grimsel granite feldspars were two to three times higher than the porosities of the El Berrocal and Los Ratones granites feldspars. However, there was no significant difference between the porosities of the dark minerals. A clear difference was found between the various quartz grains. Quartz crystals were non-porous in the El Berrocal and Los Ratones granites when measured by the PMMA method, but the quartz crystals in the Grimsel granite showed 0.5% intra granular porosity. The apparent diffusion coefficients calculated for uranium diffusion within Grimsel granite on different minerals were very similar (2.10{sup -13} {+-} 0.5 m{sup 2}/s), but differences within both Spanish granites were found from one mineral to another (9 {+-} 1.10{sup -14} m

  19. Interplay between cataclasis, clay mineral diagenesis and porosity reduction in deformation bands in unconsolidated arkosic sands

    NASA Astrophysics Data System (ADS)

    Lommatzsch, Marco; Exner, Ulrike; Gier, Susanne

    2013-04-01

    As a response to tectonic and gravitational stresses, unconsolidated sediments can develop zones of localized deformation, commonly described as deformation bands. These are tabular fault zones in high porosity rocks and sediments characterized by small offsets causing reduction of porosity through grain rotation, translation and fracturing. Classified by deformation mechanism and depth of formation, there are two main types of deformation bands: disaggregation bands, where compaction is achieved only by grain rotation and translation, and cataclastic bands, which show intense grain size reduction by grain fracturing. In various examples the porosity and permeability reduction in these fault zones inhibits the flow of fluids. The timing of deformation band formation relative to diagenesis and fluid migration is relevant in relation to the quality and connectivity of hydrocarbon or groundwater reservoirs. The investigated outcrop in a sandpit near Eisenstadt (Eisenstadt-Sopron Basin, Austria) exposes numerous conjugate deformation bands, which are formed in lower Miocene uncemented, arkosic sands and gravels. These deformation bands formed at shallow burial depth (< 1km) and are kinematically related to the nearby Eisenstadt Fault. This outcrop offers the unique possibility to investigate deformation bands with identical kinematic boundary conditions in highly variable sediments, i.e. with a wide range of different grain sizes from fine sand to coarse gravel, variable porosity and mineral content, different stages of diagenesis and carbonate-free or carbonatic sediments. The fact that cataclasis is one of the dominant mechanisms at these shallow depths (< 1km) is unusual and an exception to most cataclastic bands described in literature. This is probably related to the composition, coarse grain size and the high porosity of the sediments. The coarse host sediment mainly consists of detrital quartz, albite, biotite, sericite, muscovite and metamorphic lithoclasts

  20. Porosity and permeability relationships of edifice-forming andesites: A combined field and laboratory study

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    In volcanic settings, permeability is a key parameter controlling eruptive style and magnitude of eruptive activity by influencing the capacity for a volcano to outgas. The relative ease by which these volatiles can outgas depends on the connectivity and mobility of bubbles within the conduit and the permeability of the edifice. To explore the permeability and porosity of edifice-forming rocks, a field campaign was undertaken in May/June 2014 at Volcán de Colima, an active and currently erupting stratovolcano in Mexico. The density (used to infer porosity) and permeability of around 600 rock samples, collected from several debris-flow tracks, were measured using a field Archimedean double-weight method and a portable field permeameter, respectively. Permeability was found to range between 7.6 x 10-16 to 6.5 x 10-11 m2 across a porosity range of 2.5 to 73%. The permeability data are notably scattered, with up to four orders of magnitude difference in permeability observable for rocks of similar porosity. Scatter in the data is attributed to the wide variety in rock microstructure (due to variable vesiculation and deformation during emplacement, as well as pre- or post-emplacement alteration). Our density measurements highlight that the proportion of dense rocks increases with distance from the active dome. To complement these field data, a subset of samples (spanning the range of porosity) were brought back to the laboratory for gas permeability and porosity measurements, as well as further properties such as specific surface. Statistical analysis of the laboratory permeability-porosity data suggests a critical porosity threshold may exist, above which increased connectivity yields more efficient fluid transport. Finally, we also collected a suite of field samples containing subplanar deformation bands and tuffisites, features common to many of the rocks comprising the edifice. Laboratory permeability analysis demonstrates that some features act as conduits while