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Sample records for air void contents

  1. A novel random void model and its application in predicting void content of composites based on ultrasonic attenuation coefficient

    NASA Astrophysics Data System (ADS)

    Lin, Li; Zhang, Xiang; Chen, Jun; Mu, Yunfei; Li, Ximeng

    2011-06-01

    A novel two-dimensional random void model (RVM) based on random medium theory and a statistical method is proposed to describe random voids in composite materials. The spatial autocorrelation function and statistical parameters are used to describe the large-scale heterogeneity from the composite matrix and the small-scale heterogeneities of elastic fluctuations from random voids, the values of which are determined by statistical data from microscopic observations of void morphology. A RVM for CFRP (carbon fiber reinforced polymer) composite specimens with void content of 0.03-4.62% is presented. It is found that the geometric morphology of voids from the RVM presents good matches to the microscopic images. Calculations of ultrasonic attenuation coefficients from the RVM at 5 MHz are much closer to the experiments than those from the previous deterministic model. Furthermore, the RVM can also cover abnormal coefficients from unusually large voids, which unpredictably occur during the composite preparation and have a detrimental effect on the strength and mechanical properties of the components. The significant enhancements in description of void morphology and quantitative correlation between void content and ultrasonic attenuation coefficient make this method a good candidate for predicting void content of composite materials non-destructively.

  2. Compensation for air voids in photoacoustic computed tomography image reconstruction

    NASA Astrophysics Data System (ADS)

    Matthews, Thomas P.; Li, Lei; Wang, Lihong V.; Anastasio, Mark A.

    2016-03-01

    Most image reconstruction methods in photoacoustic computed tomography (PACT) assume that the acoustic properties of the object and the surrounding medium are homogeneous. This can lead to strong artifacts in the reconstructed images when there are significant variations in sound speed or density. Air voids represent a particular challenge due to the severity of the differences between the acoustic properties of air and water. In whole-body small animal imaging, the presence of air voids in the lungs, stomach, and gastrointestinal system can limit image quality over large regions of the object. Iterative reconstruction methods based on the photoacoustic wave equation can account for these acoustic variations, leading to improved resolution, improved contrast, and a reduction in the number of imaging artifacts. However, the strong acoustic heterogeneities can lead to instability or errors in the numerical wave solver. Here, the impact of air voids on PACT image reconstruction is investigated, and procedures for their compensation are proposed. The contributions of sound speed and density variations to the numerical stability of the wave solver are considered, and a novel approach for mitigating the impact of air voids while reducing the computational burden of image reconstruction is identified. These results are verified by application to an experimental phantom.

  3. Effects of void size and gas content on electrical breakdown in lightweight, mechanically compliant, void-filled dielectrics

    NASA Astrophysics Data System (ADS)

    Anderson, R. A.; Lagasse, R. R.; Russick, E. M.; Schroeder, J. L.

    2002-03-01

    Dielectric potting materials (encapsulants) are used to prevent air breakdown in high-voltage electrical devices. We report breakdown strengths in void-filled encapsulants, stressed with unipolar voltage pulses of the order of 10 μs duration. High strengths, on the order of 100 kV mm-1, are measured under these test conditions. The materials studied include low-density open celled gel-derived foams with cell sizes of 4 μm or less, closed celled CO2-blown polystyrene and urethane foams, and epoxies containing 48 vol % of hollow glass microballoon (GMB) fillers. These last specimens varied the void gas (N2 or SO2) and also the void diameters (tens to hundreds of μm). Our measurements are thought to be directly sensitive to the rate of field-induced ionization events in the void gas; however, the breakdown strengths of the materials tested appeared to vary in direct proportion with the conventional Paschen-law gas-discharge inception threshold, the electric stress at which gas-ionization avalanches become possible. The GMB-epoxy specimens displayed this type of dependence of breakdown strength on the void-gas density and void size, but the measurements were an order of magnitude above the conventional predictions. Small-celled foams also showed increased breakdown strengths with decreased cell size, although their irregular void geometry prevented a direct comparison with the more uniformly structured microballoon-filled encapsulants. The experimental observations are consistent with a breakdown mechanism in which the discharge of a few voids can launch a full breakdown in the composite material.

  4. Response of entrained air-void systems in cement paste to pressure

    NASA Astrophysics Data System (ADS)

    Frazier, Robert

    2011-12-01

    Scope and Method of Study: Determine the response of entrained air-void systems in fresh cement paste to applied pressures by utilizing micro-computed tomography. Compare results to those suggested by the ASTM C231 Type B pressure meter calibration equations. Findings and Conclusions: The results of this research suggest that although the Type B pressure meter assumptions are valid for the compression of individual voids, the volume of air-voids which dissolve under pressure is significant enough to register noticeable errors when using a synthetic air-entraining admixture with the Type B pressure meter test. Results currently suggest that air-void systems with a significant percentage of small voids present will have higher deviation from the Boyle's Law model used by the Type B pressure meter due to the dissolution of these air-voids.

  5. Microscopic air void analysis of hardened Portland cement concrete by the isolated shadow technique

    NASA Astrophysics Data System (ADS)

    Harris, Basil Mark

    The Isolated Shadow Technique is an image processing and analysis procedure for identifying and characterizing surface voids dispersed on an otherwise flat plane of heterogeneous solids. The objective of the Isolated Shadow Technique is to capture, process, and analyze images of a flat surface in which all of the features, save the boundary outlines of any surface voids, are eliminated. In short, the technique utilizes a series of digital images of the subject planar surface; where each image of the series is subjected to a unique lighting condition. By positioning the lights such that the shadows cast into the craters vary between images, these variations can be sequestered and the edges of the voids can subsequently be reconstructed from the isolated shadows. The primary purpose of this work was the development of the Isolated Shadow Technique for the particular application of quantitatively describing the microscopic voids in hardened Portland cement concrete. The Isolated Shadow System was developed for this application of the technique. The hardware and software of the system are described and the function is demonstrated. The system was found to have an average accuracy of 2.7% with a maximum deviation of 5.0% when compared to physical measurements. The results of polished sections of concrete specimens characterized by the Isolated Shadow System are compared to the results obtained with the commonly used standard methods (ASTM C 457; A and B). The coefficients of variation of parameters calculated to describe the air-void system (according to the ASTM C 457 formulations) are shown to be in the neighborhood of one percent when the observed test area includes at least 7,830 mmsp2 of polished concrete (with paste contents ranging from approximately 28% to 32%). The sensitivity of the air-void system parameters (as computed by the system) to changes in magnification and mosaic size are evaluated. A critical analysis of the underlying assumptions of the ASTM C

  6. EFFECTS OF OXYGEN AND AIR MIXING ON VOID FRACTIONS IN A LARGE SCALE SYSTEM

    SciTech Connect

    Leishear, R; Hector Guerrero, H; Michael Restivo, M

    2008-09-11

    Oxygen and air mixing with spargers was performed in a 30 foot tall by 30 inch diameter column, to investigate mass transfer as air sparged up through the column and removed saturated oxygen from solution. The mixing techniques required to support this research are the focus of this paper. The fluids tested included water, water with an antifoam agent (AFA), and a high, solids content, Bingham plastic, nuclear waste simulant with AFA, referred to as AZ01 simulant, which is non-radioactive. Mixing of fluids in the column was performed using a recirculation system and an air sparger. The re-circulation system consisted of the column, a re-circulating pump, and associated piping. The air sparger was fabricated from a two inch diameter pipe concentrically installed in the column and open near the bottom of the column. The column contents were slowly re-circulated while fluids were mixed with the air sparger. Samples were rheologically tested to ensure effective mixing, as required. Once the fluids were adequately mixed, oxygen was homogeneously added through the re-circulation loop using a sintered metal oxygen sparger followed by a static mixer. Then the air sparger was re-actuated to remove oxygen from solution as air bubbled up through solution. To monitor mixing effectiveness several variables were monitored, which included flow rates, oxygen concentration, differential pressures along the column height, fluid levels, and void fractions, which are defined as the percent of dissolved gas divided by the total volume of gas and liquid. Research showed that mixing was uniform for water and water with AFA, but mixing for the AZ101 fluid was far more complex. Although mixing of AZ101 was uniform throughout most of the column, gas entrapment and settling of solids significantly affected test results. The detailed test results presented here provide some insight into the complexities of mixing and void fractions for different fluids and how the mixing process itself

  7. Influence of fundamental material properties and air void structure on moisture damage of asphalt mixes

    NASA Astrophysics Data System (ADS)

    Arambula Mercado, Edith

    2007-12-01

    Moisture damage in asphalt mixes refers to the loss of serviceability due to the presence of moisture. The extent of moisture damage, also called moisture susceptibility, depends on internal and external factors. The internal factors relate to the properties of the materials and the microstructure distribution, while the external factors include the environmental conditions, production and construction practices, pavement design, and traffic level. The majority of the research on moisture damage is based on the hypothesis that infiltration of surface water is the main source of moisture. Of the two other principal mechanisms of water transport, permeation of water vapor and capillary rise of subsurface water, the latter has been least explored. A laboratory test and analysis methods based on X-ray computed tomography (CT) were established to assess the capillary rise of water. The amount and size of air voids filled with water were used in the capillary rise equation to estimate the distribution of the contact angles between the water and the mastic. The results were able to show the influence of air void size on capillary rise and contact angles. The relationship between air void structure and moisture susceptibility was evaluated using a fundamental fracture model based on dissipated energy of viscoelastic materials. Detailed description is provided in this dissertation on the deduction of the model equation, the selection of the model parameters, and the required testing protocols. The model parameters were obtained using mechanical tests and surface energy measurements. The microstructure of asphalt mixes prepared in the laboratory having different air void structures was captured using X-ray CT, and image analysis techniques were used to quantify the air void structure and air void connectivity. The air void structure was found to influence the mix resistance to moisture damage. To validate the fracture model, asphalt mixes with known field performance were

  8. Investigation of Proprietary Air-Entraining Admixtures to Produce Frost- Resistant Concrete with Low Air Content

    DTIC Science & Technology

    1992-03-01

    given air content, a higher specific surface should result in a smaller spacing factor ( Mindess and Young 1981). Therefore, if a particular AEA produced...MS. Mindess , S., and Young, J. F. 1981. Concrete, Prentice-Hall, Englewood Cliffs, NJ. Powers, T. C. 1954 (May). "Void Spacing as a Basis for

  9. Air-void embedded GaN-based light-emitting diodes grown on laser drilling patterned sapphire substrates

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Li, Yufeng; Wang, Shuai; Feng, Lungang; Xiong, Han; Su, Xilin; Yun, Feng

    2016-07-01

    Air-void structure was introduced in GaN-based blue light-emitting diodes (LED) with one-step growth on periodic laser drilling patterned sapphire substrate, which free of any photolithography or wet/dry etching process. The influence of filling factors (FF) of air-void on crystal quality and optical performance were investigate. Transmission electron microscopy images and micro-Raman spectroscopy indicated that the dislocation was bended and the partially compressed strain was released. When FF was 55.43%, compared with the LED structure grown on flat sapphire substrate, the incorporation of air-void was observed to reduce the compressed stress of ˜20% and the luminance intensity has improved by 128%. Together with the simulated reflection intensity enhancement by finite difference time-domain (FDTD) method, we attribute the enhanced optical performance to the combined contribution of strong back-side light reflection of air-void and better GaN epitaxial quality. This approach provides a simple replacement to the conventional air-void embedded LED process.

  10. Estimation of air void and aggregate spatial distributions in concrete under uniaxial compression using computer tomography scanning

    SciTech Connect

    Wong, R.C.K. . E-mail: rckwong@ucalgary.ca; Chau, K.T.

    2005-08-01

    Normal- and high-strength concrete cylinders (designed compressive strengths of 30 and 90 MPa at 28 days) were loaded uniaxially. Computer tomography (CT) scanning technique was used to examine the evolution of air voids inside the specimens at various loading states up to 85% of the ultimate compressive strength. The normal-strength concrete yielded a very different behaviour in changes of internal microstructure as compared to the high-strength concrete. There were significant instances of nucleation and growth in air voids in the normal-strength concrete specimen, while the increase in air voids in the high-strength concrete specimen was insignificant. In addition, CT images were used for mapping the aggregate spatial distributions within the specimens. No intrinsic anisotropy was detected from the fabric analysis.

  11. Measurement of air distribution and void fraction of an upwards air-water flow using electrical resistance tomography and a wire-mesh sensor

    NASA Astrophysics Data System (ADS)

    Olerni, Claudio; Jia, Jiabin; Wang, Mi

    2013-03-01

    Measurements on an upwards air-water flow are reported that were obtained simultaneously with a dual-plane electrical resistance tomograph (ERT) and a wire-mesh sensor (WMS). The ultimate measurement target of both ERT and WMS is the same, the electrical conductivity of the medium. The ERT is a non-intrusive device whereas the WMS requires a net of wires that physically crosses the flow. This paper presents comparisons between the results obtained simultaneously from the ERT and the WMS for evaluation and calibration of the ERT. The length of the vertical testing pipeline section is 3 m with an internal diameter of 50 mm. Two distinct sets of air-water flow rate scenarios, bubble and slug regimes, were produced in the experiments. The fast impedance camera ERT recorded the data at an approximate time resolution of 896 frames per second (fps) per plane in contrast with the 1024 fps of the wire-mesh sensor WMS200. The set-up of the experiment was based on well established knowledge of air-water upwards flow, particularly the specific flow regimes and wall peak effects. The local air void fraction profiles and the overall air void fraction were produced from two systems to establish consistency for comparison of the data accuracy. Conventional bulk flow measurements in air mass and electromagnetic flow metering, as well as pressure and temperature, were employed, which brought the necessary calibration to the flow measurements. The results show that the profiles generated from the two systems have a certain level of inconsistency, particularly in a wall peak and a core peak from the ERT and WMS respectively, whereas the two tomography instruments achieve good agreement on the overall air void fraction for bubble flow. For slug flow, when the void fraction is over 30%, the ERT underestimates the void fraction, but a linear relation between ERT and WMS is still observed.

  12. Void Dynamics

    NASA Astrophysics Data System (ADS)

    Padilla, Nelson D.; Paz, Dante; Lares, Marcelo; Ceccarelli, Laura; Lambas, Diego Garcí A.; Cai, Yan-Chuan; Li, Baojiu

    2016-10-01

    Cosmic voids are becoming key players in testing the physics of our Universe.Here we concentrate on the abundances and the dynamics of voids as these are among the best candidatesto provide information on cosmological parameters. Cai, Padilla & Li (2014)use the abundance of voids to tell apart Hu & Sawicki f(R) models from General Relativity. An interestingresult is that even though, as expected, voids in the dark matter field are emptier in f(R) gravity due to the fifth force expellingaway from the void centres, this result is reversed when haloes are used to find voids. The abundance of voids in this casebecomes even lower in f(R) compared to GR for large voids. Still, the differences are significant and thisprovides a way to tell apart these models. The velocity field differences between f(R) and GR, on the other hand, arethe same for halo voids and for dark matter voids.Paz et al. (2013), concentrate on the velocity profiles around voids. First they show the necessityof four parameters to describe the density profiles around voids given two distinct voidpopulations, voids-in-voids and voids-in-clouds. This profile is used to predict peculiar velocities around voids,and the combination of the latter with void density profiles allows the construction of modelvoid-galaxy cross-correlation functions with redshift space distortions. When these modelsare tuned to fit the measured correlation functions for voids and galaxies in the SloanDigital Sky Survey, small voids are found to be of the void-in-cloud type, whereas largerones are consistent with being void-in-void. This is a novel result that is obtaineddirectly from redshift space data around voids. These profiles can be used toremove systematics on void-galaxy Alcock-Pacinsky tests coming from redshift-space distortions.

  13. Effect of initial oxygen content on the void swelling behavior of fast neutron irradiated copper

    SciTech Connect

    Zinkle, S.J.; Garner, F.A.

    1998-03-01

    Density measurements were performed on high purity copper specimens containing {le}10 wt.ppm and {approximately}120 wt.ppm oxygen following irradiation in FFTF MOTA 2B. Significant amounts of swelling were observed in both the oxygen-free and oxygen-doped specimens following irradiation to {approximately}17 dpa at 375 C and {approximately}47 dpa at 430 C. Oxygen doping up to 360 appm (90 wt.ppm) did not significantly affect the void swelling of copper for these irradiation conditions.

  14. Dark matter in voids

    NASA Astrophysics Data System (ADS)

    Fong, Richard; Doroshkevich, Andrei G.; Turchaninov, Victor I.

    1995-07-01

    The theory of the formation of large-scale structure in the universe through the action of gravitational instability imply the existence of substantial amounts of baryonic dark matter, of the order of 50% of the total baryon content in the universe, in the ``voids'' or under-dense regions seen in the large-scale distribution of galaxies. We discuss also the large-scale structure of dark matter expected in voids and the present and future possibilities for the observation of this baryonic dark matter in ``voids.''

  15. Simulating Voids

    NASA Astrophysics Data System (ADS)

    Goldberg, David M.; Vogeley, Michael S.

    2004-04-01

    We present a novel method for the simulation of the interior of large cosmic voids, suitable for the study of the formation and evolution of objects lying within such regions. Following Birkhoff's theorem, void regions dynamically evolve as universes with cosmological parameters that depend on the underdensity of the void. We derive the values of ΩM, ΩΛ, and H0 that describe this evolution. We examine how the growth rate of structure and scale factor in a void differ from the background universe. Together with a prescription for the power spectrum of fluctuations, these equations provide the initial conditions for running specialized void simulations. The increased efficiency of such simulations, in comparison to general-purpose simulations, allows an improvement of upward of 20 in the mass resolution. As a sanity check, we run a moderate-resolution simulation (N=1283 particles) and confirm that the resulting mass function of void halos is consistent with other theoretical and numerical models.

  16. Flow pattern, void fraction and pressure drop of two-phase air-water flow in a horizontal circular micro-channel

    SciTech Connect

    Saisorn, Sira; Wongwises, Somchai

    2008-01-15

    Adiabatic two-phase air-water flow characteristics, including the two-phase flow pattern as well as the void fraction and two-phase frictional pressure drop, in a circular micro-channel are experimentally studied. A fused silica channel, 320 mm long, with an inside diameter of 0.53 mm is used as the test section. The test runs are done at superficial velocity of gas and liquid ranging between 0.37-16 and 0.005-3.04 m/s, respectively. The flow pattern map is developed from the observed flow patterns i.e. slug flow, throat-annular flow, churn flow and annular-rivulet flow. The flow pattern map is compared with those of other researchers obtained from different working fluids. The present single-phase experiments also show that there are no significant differences in the data from the use of air or nitrogen gas, and water or de-ionized water. The void fraction data obtained by image analysis tends to correspond with the homogeneous flow model. The two-phase pressure drops are also used to calculate the frictional multiplier. The multiplier data show a dependence on flow pattern as well as mass flux. A new correlation of two-phase frictional multiplier is also proposed for practical application. (author)

  17. Characterizing the effects of elevated temperature on the air void pore structure of advanced gas-cooled reactor pressure vessel concrete using x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Stein, R. C.; Petkovski, M.; Engelberg, D. L.; Leonard, F.; Withers, P. J.

    2013-07-01

    X-ray computed tomography (X-ray CT) has been applied to nondestructively characterise changes in the microstructure of a concrete used in the pressure vessel structure of Advanced Gas-cooled Reactors (AGR) in the UK. Concrete specimens were conditioned at temperatures of 105 °C and 250 °C, to simulate the maximum thermal load expected to occur during a loss of coolant accident (LOCA). Following thermal treatment, these specimens along with an unconditioned control sample were characterised using micro-focus X-ray CT with a spatial resolution of 14.6 microns. The results indicate that the air void pore structure of the specimens experienced significant volume changes as a result of the increasing temperature. The increase in the porous volume was more prevalent at 250 °C. Alterations in air void size distributions were characterized with respect to the unconditioned control specimen. These findings appear to correlate with changes in the uni-axial compressive strength of the conditioned concrete.

  18. Method to Estimate the Dissolved Air Content in Hydraulic Fluid

    NASA Technical Reports Server (NTRS)

    Hauser, Daniel M.

    2011-01-01

    In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated

  19. The effects of channel diameter on flow pattern, void fraction and pressure drop of two-phase air-water flow in circular micro-channels

    SciTech Connect

    Saisorn, Sira; Wongwises, Somchai

    2010-05-15

    Two-phase air-water flow characteristics are experimentally investigated in horizontal circular micro-channels. Test sections are made of fused silica. The experiments are conducted based on three different inner diameters of 0.53, 0.22 and 0.15 mm with the corresponding lengths of 320, 120 and 104 mm, respectively. The test runs are done at superficial velocities of gas and liquid ranging between 0.37-42.36 and 0.005-3.04 m/s, respectively. The flow visualisation is facilitated by systems mainly including stereozoom microscope and high-speed camera. The flow regime maps developed from the observed flow patterns are presented. The void fractions are determined based on image analysis. New correlation for two-phase frictional multiplier is also proposed for practical applications. (author)

  20. Development of AN Intensity Based Fiber Optic Sensor and Predictive Models for in Situ Void Detection during Polymer Composite Cure.

    NASA Astrophysics Data System (ADS)

    Klosterman, Donald A.

    The use of an optic fiber as an in situ sensor for void detection in polymer composites has been investigated. The sensor is prepared from standard multimode optic fiber by removing a 1-cm length of coating and cladding to expose the core. The sensor was designed to detect entrapped bubbles of water and solvents produced during a cure cycle, or interlaminar pockets of air that have been trapped during the layup process. The sensor signal is the total transmitted light intensity through the optic fiber and is affected by the refractive index of the resin and the amount of voids that contact the exposed core. The measured void content corresponds to the fractional area of the exposed core covered with voids. A mathematical model was developed to predict the sensor signal given the inputs of resin refractive index and void content. Experiments were performed in neat resin to verify the model. Initially, the model was tuned to changes in the resin refractive index by heating in a noncuring resin with a void content of zero. Tuning was accomplished by adjusting the distribution of power among optical modes, an internal model parameter. The tuned model was then verified for the condition of a changing void content and constant refractive index. An experiment with neat resin and water droplets was used to verify the model for simultaneous changes in resin refractive index and void content. It was determined that the sensor signal is affected by the overall void content; the model was used to predict that the signal varies only 1% for different void distributions of the same overall void content. The sensor signal was collected for the void-free cure of neat Hercules 3501-6 epoxy resin. To verify the model for the cure of 3501-6 resin, it was necessary to measure the resin refractive index as a function of temperature and degree of cure. Two methods were used to obtain this calibration: ellipsometry and a direct method using the sensor model and acquired sensor signal. The

  1. Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air-water flows

    NASA Astrophysics Data System (ADS)

    Borges, João Eduardo; Pereira, Nuno H. C.; Matos, Jorge; Frizell, Kathleen H.

    2010-01-01

    The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air-water flows, is described in this paper. The air-water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air-water flows.

  2. Evaluation of ergosterol content in the air of various environments.

    PubMed

    Gutarowska, Beata; Skóra, Justyna; Pielech-Przybylska, Katarzyna

    The aim of the study was to compare the content of ergosterol in different microorganisms (bacteria, yeasts and moulds) isolated from the air as well as in six species of moulds in their different morphological forms-live mycelium, dead mycelium, and spores. Evaluation of the level of mould contamination of the air in various places using culture method and ergosterol determination was also performed. The analysis of ergosterol was carried out by gas chromatography equipped with flame ionisation detector. For evaluation of the results, analysis of variance and multiple comparison test were used. The quantity of ergosterol in the spores of various species of mould was in the range 1.9-9.4 pg/spore. The presence of yeasts and bacteria in the air does not significantly affect ergosterol concentration, in view of the low content of that sterol in their cells (max. 0.009 pg/cell for bacteria and 0.39 pg/cell for yeast). An ergosterol concentration above 1 ng per m(3) can be considered an indicator of excessive mould contamination of indoor air. Based on determination of ergosterol in the air of mouldy rooms the result obtained may be compared with the culture method, due to the 1,000 times higher concentration of ergosterol in the mycelium compared with spores. However, in the analysis of outdoor air, in view of the presence of mould mainly in the form of spores and the degradation of ergosterol by UV radiation, analysis of that compound may indicate a lower level of contamination compared with the culture method.

  3. Air permeability of compost as related to bulk density and volumetric air content.

    PubMed

    Poulsen, Tjalfe G; Moldrup, Per

    2007-08-01

    Compost air permeability controls air flow through compost during composting or when using compost as biofilter material. Air permeability is therefore an important characteristic of compost. The relationships between air permeability (k(a)) in compost and compost dry bulk density (rho b), gravimetric water content (omega), and volumetric air content (epsilon) was investigated for two types of composts. The composts used were produced from a digested sewage sludge-straw mixture and from garden waste and measurements were conducted on sieved and repacked 100 cm3 compost samples. Results showed a linear relation between log(k(a)) and rho b at constant values of omega for both composts, indicating an exponential relationship between k(a) and rho b. The slopes of these relationships generally became more negative with increasing rho b. The results further showed a linear relationship between log(k(a)) and log(epsilon) for both composts as also often observed for soils. It was observed that the log(k(a)) and log(epsilon) relationships for the garden waste compost all intercepted at the same location despite having very different slopes. This means that it is possible to predict the entire k(a)-epsilon relationship using only one measurement of corresponding (k(a), epsilon) for garden waste. It was not possible to determine whether this was also the case for the sewage sludge compost due to difficulties in sample preparation at low and high water content.

  4. The Void Specification

    SciTech Connect

    Cook, B

    2005-04-23

    The purpose of this memo is to explore more fully the allowable void specification, in part to make it clearer to those doing the day-to-day evaluation and in part to help me understand the ramifications. A simulation of voids in a Be shell is used to support my understanding of Haan's analysis. The key results showing allowable void diameter as a function of void fraction are shown in Figure 6 (p. 8). What is important here is that generally in ''good'' samples we only see small voids, perhaps at most a few tenths of a {micro}m in size. For this void size the shells can be underdense by as much as 10% and still meet the 1 part in 10{sup 4} spec (though there may be other issues with reduced density).

  5. EPA Void Letter for Suzuki

    EPA Pesticide Factsheets

    When a certificate is voided, EPA issues a void letter to the manufacturer.November 30, 2016, letter from Byron Bunker to Suzuki Motor America Inc., voiding certificate of conformity for highway motorcycle engine family CSKXC.652VR1.

  6. Draining the Local Void

    NASA Astrophysics Data System (ADS)

    Rizzi, Luca; Tully, R. Brent; Shaya, Edward J.; Kourkchi, Ehsan; Karachentsev, Igor D.

    2017-01-01

    Two galaxies that lie deep within the Local Void provide a test of the expectation that voids expand. The modest ({M}B∼ -14) HI bearing dwarf galaxies ALFAZOAJ1952+1428 and KK246 have been imaged with Hubble Space Telescope in order to study the stellar populations and determine distances from the luminosities of stars at the tip of the red giant branch. The mixed age systems have respective distances of 8.39 Mpc and 6.95 Mpc and inferred line-of-sight peculiar velocities of ‑114 km s‑1 and ‑66 km s‑1 toward us and away from the void center. These motions compound on the Milky Way motion of ∼230 km s‑1 away from the void. The orbits of the two galaxies are reasonably constrained by a numerical action model encompassing an extensive region that embraces the Local Void. It is unambiguously confirmed that these two void galaxies are moving away from the void center at several hundred km s‑1.

  7. The Star Formation History of Void Galaxies

    NASA Astrophysics Data System (ADS)

    Stanonik, Kathryn

    The Cosmic Web that permeates our universe is defined by the alignment of galaxies into filaments, clusters, and walls, as well as by the voids between them which are (mostly) empty. Void galaxies, found occupying these underdense regions, are an environmentally defined population whose isolated nature and extreme environment provides an ideal opportunity to test theories of galaxy formation and evolution. Their existence also poses a well defined observational constraint to Lambda CDM cosmological models. We propose to do UV imaging of a sample of SDSS selected void galaxies located in the deepest underdensities of nearby voids. Our galaxies were selected using the Delaunay Tesselation Field estimator, a novel, purely structural and geometric technique, to produce a sample that more uniformly represents the void galaxy population. In addition, we use a powerful new backend of the Westerbork Synthesis Radio Telescope that allows us to probe the neutral gas content in a huge volume around each targeted void galaxy, while still resolving individual galaxy kinematics and detecting faint companions in H I. We specifically aim to study the star formation history of these systems, which appear to be in a more youthful stage of their evolution than field galaxies. With this combination of UV and H I data we will address questions ranging from how galaxies get their gas, how they form stars, and what role environment plays in these processes.

  8. Illicit psychotropic substance contents in the air of Italy

    NASA Astrophysics Data System (ADS)

    Cecinato, Angelo; Balducci, Catia; Budetta, Valentina; Pasini, Antonello

    2010-06-01

    Two in-field campaigns were performed in 2009 to elucidate the contents of illicit psychotropic substances in airborne particulates of Italian cities. Twenty-eight localities of eight Italian regions were investigated in winter, and further eleven sites in June (14 regions in total), thanks to contribution of Regional Environmental Agencies. Cocaine was found almost everywhere, although some sites were rural or suburban. The maximum was recorded in Milan in winter (˜0.39 ng m -3), and "high" values (up to ˜0.16 ng m -3) in other Northern cities and in Rome. Besides cocaine, three cannabinoids will be monitored, namely Δ 9-tetrahydrocannabinol, cannabidiol and cannabinol. The three compounds often affected the air at lower extents than cocaine, and sometimes resulted absent. Cannabinol accounted for up to 90% of the total. The concentrations of illicit compounds were up to six times lower in June than in winter. This decrease was probably induced by the lowering of boundary layer height typical of winter, and by the oxidizing capacity of atmosphere, which is stronger in the warm season. Compared to n-alkanes, polynuclear aromatic compounds, nicotine, caffeine and airborne particulate, cocaine seemed to follow a peculiar behaviour; in fact, meaningful (≥0.80) Pearson (linear) regression coefficients were calculated from the corresponding concentrations only at local scale (e.g. Rome), and within just one season. Improvements of the method are needed to monitor illicit drug metabolites (e.g. benzoylecgonine, ecgonine methyl ester, 9-carboxy-11-nor-Δ 9-tetrahydrocannabinol), heroin and semi-volatile amphetamines.

  9. Void/particulate detector

    DOEpatents

    Claytor, Thomas N.; Karplus, Henry B.

    1985-01-01

    Voids and particulates are detected in a flowing stream of fluid contained in a pipe by a detector which includes three transducers spaced about the pipe. A first transducer at a first location on the pipe transmits an ultrasonic signal into the stream. A second transducer detects the through-transmission of the signal at a second location and a third transducer at a third location upstream from the first location detects the back-scattering of the signal from any voids or particulates. To differentiate between voids and particulates a fourth transducer is positioned at a fourth location which is also upstream from the first location. The back-scattered signals are normalized with the through-transmission signal to minimize temperature fluctuations.

  10. Thermal inertia mapping of below ground objects and voids

    NASA Astrophysics Data System (ADS)

    Del Grande, Nancy K.; Ascough, Brian M.; Rumpf, Richard L.

    2013-05-01

    Thermal inertia (effusivity) contrast marks the borders of naturally heated below ground object and void sites. The Dual Infrared Effusivity Computed Tomography (DIRECT) method, patent pending, detects and locates the presence of enhanced heat flows from below ground object and void sites at a given area. DIRECT maps view contrasting surface temperature differences between sites with normal soil and sites with soil disturbed by subsurface, hollow or semi-empty object voids (or air gaps) at varying depths. DIRECT utilizes an empirical database created to optimize the scheduling of daily airborne thermal surveys to view and characterize unseen object and void types, depths and volumes in "blind" areas.

  11. Dysfunctional voiding in adults.

    PubMed

    Haifler, Miki; Stav, Kobi

    2013-05-01

    Dysfunctional voiding is characterized by an intermittent and/or fluctuating flow rate due to involuntary intermittent contractions of the periurethral striated or levator muscles during voiding in neurologically normal women (International Continence Society definition). Due to the variable etiology, the diagnosis and treatment of DV is problematic. Frequently, the diagnosis is done at a late stage mainly due to non-specific symptoms and lack of awareness. The objectives of treatment are to normalize micturition patterns and prevent complications such as renal failure and recurrent infections. Treatment should be started as early as possible and a multidisciplinary approach is beneficial.

  12. A Simple Experiment To Measure the Content of Oxygen in the Air Using Heated Steel Wool

    ERIC Educational Resources Information Center

    Vera, Francisco; Rivera, Rodrigo; Nunez, Cesar

    2011-01-01

    The typical experiment to measure the oxygen content in the atmosphere uses the rusting of steel wool inside a closed volume of air. Two key aspects of this experiment that make possible a successful measurement of the content of oxygen in the air are the use of a closed atmosphere and the use of a chemical reaction that involves the oxidation of…

  13. Dynamics of void collapse in shocked energetic materials: physics of void-void interactions

    NASA Astrophysics Data System (ADS)

    Kapahi, A.; Udaykumar, H. S.

    2013-11-01

    This work presents the response of a porous energetic material subjected to severe transient loading conditions. The porosities, represented by voids, entirely change the response of an otherwise homogeneous material. The variations in terms of energy distribution and maximum temperature reached in the material in the presence of heterogeneities (voids) but in the absence of chemical reactions are studied. This study also accounts for void-void interactions to enhance the understanding of the localization of energy in the material. It is observed that relative position of voids can have important consequence on energy distribution as well as rise in temperature of the energetic material. The relative position of voids further influences the interaction of secondary shock waves generated during the collapse of one void with the downstream voids. This interaction can either enhance or diminish the strength of the shock depending on the location of downstream voids. This work also reveals that the findings from mutual void-void interactions can be used to study systems with multiple voids. This is shown by analyzing systems with 10-25 % void volume fraction. The effect of void-void interactions are connected to the overall response of a chemically inert porous material to imposed transient loads.

  14. Actions to Void Certificates for Vehicle and Engines

    EPA Pesticide Factsheets

    n cases where EPA has determines that manufacturers have provided inaccurate, incomplete or falsified certification information or failed to keep required records, the Clean Air Act gives the EPA the authority to void certificates.

  15. Predicting seed cotton moisture content from changes in drying air temperature - second year

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mathematical model was used to predict seed cotton moisture content in the overhead section of a cotton gin. The model took into account the temperature, mass flow, and specific heat of both the air and seed cotton. Air temperatures and mass flows were measured for a second year at a commercial g...

  16. Characterization of voids formed during liquid impregnation of nonwoven multifilament glass networks as related to composite processing

    NASA Technical Reports Server (NTRS)

    Mahale, Anant D.; Prudhomme, Robert K.; Rebenfeld, Ludwig

    1993-01-01

    A technique based on matching the refractive index of an invading liquid to that of a fiber mat was used to study entrapment of air ('voids') that occurs during forced in-plane radial flow into nonwoven multifilament glass networks. The usefulness of this technique is demonstrated in quantifying and mapping the air pockets. Experiments with a series of fluids with surface tensions varying from 28 x 10(exp -3) to 36 x 10(exp -3) N/m, viscosities from 45 x 10(exp -3) to 290 x 10(exp -3) Pa.s, and inlet flow rates from 0.15 x 10(exp -6) to 0.75 x 10(exp -6) m(exp 3)/s, showed that void content is a function of the capillary number characterizing the flow process. A critical value of capillary number, Ca = 2.5 x 10(exp -3), identifies a zone below which void content increases exponentially with decreasing capillary number. Above this critical value, negligible entrapment of voids is observed. Similar experiments carried out on surface treated nonwoven mats spanning a range of equilibrium contact angles from 20 deg to 78 deg showed that there is a critical contact angle above which negligible entrapment is observed. Below this value, there is no apparent effect of contact angle on the void fraction - capillary number relationship described earlier. Studies on the effect of filament wettability, and fluid velocity and viscosity on the size of the entrapment (voids) were also carried out. These indicate that larger sized entrapments which envelop more than one pore are favored by a low capillary number in comparison to smaller, pore level bubbles. Experiments were carried out on deformed mats - imposing high permeability spots at regular intervals on a background of low permeability. The effect of these spatial fluctuations in heterogeneity of the mat on entrapment is currently being studied.

  17. Void galaxy properties depending on void filament straightness

    NASA Astrophysics Data System (ADS)

    Shim, Junsup; Lee, Jounghun; Hoyle, Fiona

    2015-08-01

    We investigate the properties of galaxies belonging to the filaments in cosmic void regions, using the void catalogue constructed by Pan et al. (2012) from the SDSS DR7. To identify galaxy filaments within a void, voids with 30 or more galaxies are selected as a sample. We identify 3172 filaments in 1055 voids by applying the filament finding algorithm utilizing minimal spanning tree (MST) which is an unique linear pattern into which connects all the galaxies in a void. We study the correlations between galaxy properties and the specific size of filament which quantifies the degree of the filament straightness. For example, the average magnitude and the magnitude of the faintest galaxy in filament decrease as the straightness of the filament increases. We also find that the correlations become stronger in rich filaments with many member galaxies than in poor ones. We discuss a physical explanation to our findings and their cosmological implications.

  18. Stress Voiding During Wafer Processing

    SciTech Connect

    Yost, F.G.

    1999-03-01

    Wafer processing involves several heating cycles to temperatures as high as 400 C. These thermal excursions are known to cause growth of voids that limit reliability of parts cut from the wafer. A model for void growth is constructed that can simulate the effect of these thermal cycles on void growth. The model is solved for typical process steps and the kinetics and extent of void growth are determined for each. It is shown that grain size, void spacing, and conductor line width are very important in determining void and stress behavior. For small grain sizes, stress relaxation can be rapid and can lead to void shrinkage during subsequent heating cycles. The effect of rapid quenching from process temperatures is to suppress void growth but induce large remnant stress in the conductor line. This stress can provide the driving force for void growth during storage even at room temperature. For isothermal processes the model can be solved analytically and estimates of terminal void size a nd lifetime are obtained.

  19. Air transport of plutonium metal: content expansion initiative for the plutonium air transportable (PAT01) packaging

    SciTech Connect

    Caviness, Michael L; Mann, Paul T

    2010-01-01

    The National Nuclear Security Administration (NNSA) has submitted an application to the Nuclear Regulatory Commission (NRC) for the air shipment of plutonium metal within the Plutonium Air Transportable (PAT-1) packaging. The PAT-1 packaging is currently authorized for the air transport of plutonium oxide in solid form only. The INMM presentation will provide a limited overview of the scope of the plutonium metal initiative and provide a status of the NNSA application to the NRC.

  20. Natural radioactivity content in soil and indoor air of Chellanam.

    PubMed

    Mathew, S; Rajagopalan, M; Abraham, J P; Balakrishnan, D; Umadevi, A G

    2012-11-01

    Contribution of terrestrial radiation due to the presence of naturally occurring radionuclides in soil and air constitutes a significant component of the background radiation exposure to the population. The concentrations of natural radionuclides in the soil and indoor air of Chellanam were investigated with an aim of evaluating the environmental radioactivity level and radiation hazard to the population. Chellanam is in the suburbs of Cochin, with the Arabian Sea in the west and the Cochin backwaters in the east. Chellanam is situated at ∼25 km from the sites of these factories. The data obtained serve as a reference in documenting changes to the environmental radioactivity due to technical activities. Soil samples were collected from 30 locations of the study area. The activity concentrations of (232)Th, (238)U and (40)K in the samples were analysed using gamma spectrometry. The gamma dose rates were calculated using conversion factors recommended by UNSCEAR [United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. UNSCEAR (2000)]. The ambient radiation exposure rates measured in the area ranged from 74 to 195 nGy h(-1) with a mean value of 131 nGy h(-1). The significant radionuclides being (232)Th, (238)U and (40)K, their activities were used to arrive at the absorbed gamma dose rate with a mean value of 131 nGy h(-1) and the radium equivalent activity with a mean value of 162 Bq kg(-1). The radon progeny levels varied from 0.21 to 1.4 mWL with a mean value of 0.6 mWL. The thoron progeny varied from 0.34 to 2.9 mWL with a mean value of 0.85 mWL. The ratio between thoron and radon progenies varied from 1.4 to 2.3 with a mean of 1.6. The details of the study, analysis and results are discussed.

  1. CTF Void Drift Validation Study

    SciTech Connect

    Salko, Robert K.; Gosdin, Chris; Avramova, Maria N.; Gergar, Marcus

    2015-10-26

    This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

  2. Removal of introduced inorganic content from chipped forest residues via air classification

    SciTech Connect

    Lacey, Jeffrey A.; Aston, John E.; Westover, Tyler L.; Cherry, Robert S.; Thompson, David N.

    2015-08-04

    Inorganic content in biomass decreases the efficiency of conversion processes, especially thermochemical conversions. The combined concentrations of specific ash forming elements are the primary attributes that cause pine residues to be considered a degraded energy conversion feedstock, as compared to clean pine. Air classification is a potentially effective and economical tool to isolate high inorganic content biomass fractions away from primary feedstock sources to reduce their ash content. In this work, loblolly pine forest residues were air classified into 10 fractions whose ash content and composition were measured. Ash concentrations were highest in the lightest fractions (5.8–8.5 wt%), and in a heavy fraction of the fines (8.9–15.1 wt%). The removal of fractions with high inorganic content resulted in a substantial reduction in the ash content of the remaining biomass in forest thinnings (1.69–1.07 wt%) and logging residues (1.09–0.68 wt%). These high inorganic content fractions from both forest residue types represented less than 7.0 wt% of the total biomass, yet they contained greater than 40% of the ash content by mass. Elemental analysis of the air classified fractions revealed the lightest fractions were comprised of high concentrations of soil elements (silicon, aluminum, iron, sodium, and titanium). However, the elements of biological origin including calcium, potassium, magnesium, sulfur, manganese, and phosphorous were evenly distributed throughout all air classified fractions, making them more difficult to isolate into fractions with high mineral concentrations. Under the conditions reported in this study, an economic analysis revealed air classification could be used for ash removal for as little as $2.23 per ton of product biomass. As a result, this study suggests air classification is a potentially attractive technology for the removal of introduced soil minerals from pine forest residues.

  3. Removal of introduced inorganic content from chipped forest residues via air classification

    DOE PAGES

    Lacey, Jeffrey A.; Aston, John E.; Westover, Tyler L.; ...

    2015-08-04

    Inorganic content in biomass decreases the efficiency of conversion processes, especially thermochemical conversions. The combined concentrations of specific ash forming elements are the primary attributes that cause pine residues to be considered a degraded energy conversion feedstock, as compared to clean pine. Air classification is a potentially effective and economical tool to isolate high inorganic content biomass fractions away from primary feedstock sources to reduce their ash content. In this work, loblolly pine forest residues were air classified into 10 fractions whose ash content and composition were measured. Ash concentrations were highest in the lightest fractions (5.8–8.5 wt%), and inmore » a heavy fraction of the fines (8.9–15.1 wt%). The removal of fractions with high inorganic content resulted in a substantial reduction in the ash content of the remaining biomass in forest thinnings (1.69–1.07 wt%) and logging residues (1.09–0.68 wt%). These high inorganic content fractions from both forest residue types represented less than 7.0 wt% of the total biomass, yet they contained greater than 40% of the ash content by mass. Elemental analysis of the air classified fractions revealed the lightest fractions were comprised of high concentrations of soil elements (silicon, aluminum, iron, sodium, and titanium). However, the elements of biological origin including calcium, potassium, magnesium, sulfur, manganese, and phosphorous were evenly distributed throughout all air classified fractions, making them more difficult to isolate into fractions with high mineral concentrations. Under the conditions reported in this study, an economic analysis revealed air classification could be used for ash removal for as little as $2.23 per ton of product biomass. As a result, this study suggests air classification is a potentially attractive technology for the removal of introduced soil minerals from pine forest residues.« less

  4. Into the Void

    NASA Technical Reports Server (NTRS)

    2006-01-01

    17 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a chain of pits on a lava- and dust-covered plain northwest of Tharsis Tholus -- one of the many volcanic constructs in the Tharsis region of Mars. Pit chains, such as this one, are associated with the collapse of surface materials into subsurface voids formed by faulting and expansion -- or extension -- of the bedrock.

    Location near: 16.4oN, 92.6oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  5. Void detecting device

    DOEpatents

    Nakamoto, Koichiro; Ohyama, Nobumi; Adachi, Kiyoshi; Kuwahara, Hajime

    1979-01-01

    A detector to be inserted into a flowing conductive fluid, e.g. sodium coolant in a nuclear reactor, comprising at least one exciting coil to receive an a-c signal applied thereto and two detecting coils located in the proximity of the exciting coil. The difference and/or the sum of the output signals of the detecting coils is computed to produce a flow velocity signal and/or a temperature-responsive signal for the fluid. Such flow velocity signal or temperature signal is rectified synchronously by a signal the phase of which is shifted substantially .+-. 90.degree. with respect to the flow velocity signal or temperature signal, thereby enabling the device to detect voids in the flowing fluid without adverse effects from flow velocity variations or flow disturbances occurring in the fluid.

  6. Effect of air moisture content on adhesion to dentine: a comparison of dental air/water syringe tips.

    PubMed

    Lau, A; Bennani, V; Chandler, N; Hanlin, S; Lowe, B

    2014-09-01

    This study aimed to evaluate the spray pattern and air moisture content produced by single-use syringe and multiple-use syringe tips. The drying efficacy was evaluated by analyzing the spray and by detecting the presence of moisture in the air blast through the tips. Single-use tips had a more consistent spray pattern and produced a moisture-free airflow compared to the multiple-use tips. The differences were statistically significant. Adhesion to dentine between tooth preparations dried with the two tips was evaluated using a tensile test. The differences were statistically insignificant.

  7. Voids in massive neutrino cosmologies

    SciTech Connect

    Massara, Elena; Villaescusa-Navarro, Francisco; Viel, Matteo; Sutter, P.M. E-mail: villaescusa@oats.inaf.it E-mail: sutter@oats.inaf.it

    2015-11-01

    Cosmic voids are a promising environment to characterize neutrino-induced effects on the large-scale distribution of matter in the universe. We perform a comprehensive numerical study of the statistical properties of voids, identified both in the matter and galaxy distributions, in massive and massless neutrino cosmologies. The matter density field is obtained by running several independent N-body simulations with cold dark matter and neutrino particles, while the galaxy catalogs are modeled by populating the dark matter halos in simulations via a halo occupation distribution (HOD) model to reproduce the clustering properties observed by the Sloan Digital Sky Survey (SDSS) II Data Release 7. We focus on the impact of massive neutrinos on the following void statistical properties: number density, ellipticities, two-point statistics, density and velocity profiles. Considering the matter density field, we find that voids in massive neutrino cosmologies are less evolved than those in the corresponding massless neutrinos case: there is a larger number of small voids and a smaller number of large ones, their profiles are less evacuated, and they present a lower wall at the edge. Moreover, the degeneracy between σ{sub 8} and Ω{sub ν} is broken when looking at void properties. In terms of the galaxy density field, we find that differences among cosmologies are difficult to detect because of the small number of galaxy voids in the simulations. Differences are instead present when looking at the matter density and velocity profiles around these voids.

  8. Artificial Voids In Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Generazio, Edward R.; Baaklini, George Y.

    1988-01-01

    Method for creating voids in ceramic specimens developed. Silicon carbide and silicon nitride are high-temperature structural ceramic materials considered for applications in advanced gas-turbine engines. Ability to detect and characterize voids (by sizes, shapes, and locations) in structural ceramics vital for increasing strengths and reliabilities of materials. Small holes made deliberately to help quantify techniques of nondestructive evaluation.

  9. Using advanced oxidation treatment for biofilm inactivation by varying water vapor content in air plasma

    NASA Astrophysics Data System (ADS)

    Ryota, Suganuma; Koichi, Yasuoka

    2015-09-01

    Biofilms are caused by environmental degradation in food factories and medical facilities. The inactivation of biofilms involves making them react with chemicals including chlorine, hydrogen peroxide, and ozone, although inactivation using chemicals has a potential problem because of the hazardous properties of the residual substance and hydrogen peroxide, which have slow reaction velocity. We successfully performed an advanced oxidation process (AOP) using air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were generated by varying the amount of water vapor supplied to the plasma. By varying the content of the water included in the air, the main product was changed from air plasma. When we increased the water content in the air, hydrogen peroxide was produced, while ozone peroxide was produced when we decreased the water content in the air. By varying the amount of water vapor, we realized a 99.9% reduction in the amount of bacteria in the biofilm when we discharged humidified air only. This work was supported by JSPS KAKENHI Grant Number 25630104.

  10. Assimilation of IASI and AIRS Data: Information Content and Quality Control

    NASA Technical Reports Server (NTRS)

    Joiner, J.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The Infrared Atmospheric Sounding Interferometer (IASI) and Atmospheric Infrared Sounder (AIRS) instruments have two orders of magnitude more channels that the current operational infrared sounder (High Resolution Infra-Red Sounder (HIRS)). This data volume presents a technological challenge for using the data in a data assimilation system. Data reduction will be a necessary for assimilation. It is important to understand the information content of the radiance measurements for data reduction purposes. In this talk, I will discuss issues relating to information content and quality control for assimilation of the AIRS and IASI data.

  11. Distinct effects of moisture and air contents on acoustic properties of sandy soil.

    PubMed

    Oshima, Takuya; Hiraguri, Yasuhiro; Okuzono, Takeshi

    2015-09-01

    Knowledge of distinct effects of moisture content and air volume on acoustic properties of soil is sought to predict the influence of human activities such as cultivation on acoustic propagation outdoors. This work used an impedance tube with the two-thickness method to investigate such effects. For a constant moisture weight percentage, the magnitude of the characteristic impedance became smaller and the absorption coefficient became higher with increase of the air space ratio. For a constant air space ratio, the absorption coefficient became larger and the magnitude of the propagation constant became smaller with increasing moisture weight percentage.

  12. Voids in modified gravity reloaded: Eulerian void assignment

    NASA Astrophysics Data System (ADS)

    Lam, Tsz Yan; Clampitt, Joseph; Cai, Yan-Chuan; Li, Baojiu

    2015-07-01

    We revisit the excursion set approach to calculate void abundances in chameleon-type modified gravity theories, which was previously studied by Clampitt, Cai & Li. We focus on properly accounting for the void-in-cloud effect, i.e. the growth of those voids sitting in overdense regions may be restricted by the evolution of their surroundings. This effect may change the distribution function of voids hence affect predictions on the differences between modified gravity (MG) and general relativity (GR). We show that the thin-shell approximation usually used to calculate the fifth force is qualitatively good but quantitatively inaccurate. Therefore, it is necessary to numerically solve the fifth force in both overdense and underdense regions. We then generalize the Eulerian-void-assignment method of Paranjape, Lam & Sheth to our modified gravity model. We implement this method in our Monte Carlo simulations and compare its results with the original Lagrangian methods. We find that the abundances of small voids are significantly reduced in both MG and GR due to the restriction of environments. However, the change in void abundances for the range of void radii of interest for both models is similar. Therefore, the difference between models remains similar to the results from the Lagrangian method, especially if correlated steps of the random walks are used. As Clampitt et al., we find that the void abundance is much more sensitive to MG than halo abundances. Our method can then be a faster alternative to N-body simulations for studying the qualitative behaviour of a broad class of theories. We also discuss the limitations and other practical issues associated with its applications.

  13. PRECISION COSMOGRAPHY WITH STACKED VOIDS

    SciTech Connect

    Lavaux, Guilhem; Wandelt, Benjamin D.

    2012-08-01

    We present a purely geometrical method for probing the expansion history of the universe from the observation of the shape of stacked voids in spectroscopic redshift surveys. Our method is an Alcock-Paczynski (AP) test based on the average sphericity of voids posited on the local isotropy of the universe. It works by comparing the temporal extent of cosmic voids along the line of sight with their angular, spatial extent. We describe the algorithm that we use to detect and stack voids in redshift shells on the light cone and test it on mock light cones produced from N-body simulations. We establish a robust statistical model for estimating the average stretching of voids in redshift space and quantify the contamination by peculiar velocities. Finally, assuming that the void statistics that we derive from N-body simulations is preserved when considering galaxy surveys, we assess the capability of this approach to constrain dark energy parameters. We report this assessment in terms of the figure of merit (FoM) of the dark energy task force and in particular of the proposed Euclid mission which is particularly suited for this technique since it is a spectroscopic survey. The FoM due to stacked voids from the Euclid wide survey may double that of all other dark energy probes derived from Euclid data alone (combined with Planck priors). In particular, voids seem to outperform baryon acoustic oscillations by an order of magnitude. This result is consistent with simple estimates based on mode counting. The AP test based on stacked voids may be a significant addition to the portfolio of major dark energy probes and its potentialities must be studied in detail.

  14. The Void Galaxy Survey: Galaxy Evolution and Gas Accretion in Voids

    NASA Astrophysics Data System (ADS)

    Kreckel, Kathryn; van Gorkom, Jacqueline H.; Beygu, Burcu; van de Weygaert, Rien; van der Hulst, J. M.; Aragon-Calvo, Miguel A.; Peletier, Reynier F.

    2016-10-01

    Voids represent a unique environment for the study of galaxy evolution, as the lower density environment is expected to result in shorter merger histories and slower evolution of galaxies. This provides an ideal opportunity to test theories of galaxy formation and evolution. Imaging of the neutral hydrogen, central in both driving and regulating star formation, directly traces the gas reservoir and can reveal interactions and signs of cold gas accretion. For a new Void Galaxy Survey (VGS), we have carefully selected a sample of 59 galaxies that reside in the deepest underdensities of geometrically identified voids within the SDSS at distances of ~100 Mpc, and pursued deep UV, optical, Hα, IR, and HI imaging to study in detail the morphology and kinematics of both the stellar and gaseous components. This sample allows us to not only examine the global statistical properties of void galaxies, but also to explore the details of the dynamical properties. We present an overview of the VGS, and highlight key results on the HI content and individually interesting systems. In general, we find that the void galaxies are gas rich, low luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. We see evidence of both ongoing assembly, through the gas dynamics between interacting systems, and significant gas accretion, seen in extended gas disks and kinematic misalignments. The VGS establishes a local reference sample to be used in future HI surveys (CHILES, DINGO, LADUMA) that will directly observe the HI evolution of void galaxies over cosmic time.

  15. Investigation on the heavy-metal content of zinc-air button cells.

    PubMed

    Richter, Andrea; Richter, Silke; Recknagel, Sebastian

    2008-01-01

    Within the framework of a German government project (initiated by the Federal Environment Agency) to check the compliance of commercially available batteries with the German Battery Ordinance concerning their heavy metal contents, 18 different types of commercially available zinc-air button cells were analysed for their cadmium, lead and mercury contents. After microwave assisted dissolution with aqua regia, Cd and Pb were determined using inductively coupled plasma mass spectrometry (ICP-MS), and Hg was determined using inductively coupled plasma optical emission spectrometry (ICP OES) and atomic absorption spectrometry. Cd contents were found to be much lower than the permitted limits; Pb contents were also found to be below the limits. Hg contents were found to be near the limits, and in one case the limit was exceeded.

  16. Moisture content, processing yield, and surface color of broiler carcasses chilled by water, air, or evaporative air.

    PubMed

    Jeong, J Y; Janardhanan, K K; Booren, A M; Karcher, D M; Kang, I

    2011-03-01

    This study was conducted to investigate the effects of water chilling (WC), air chilling (AC), and evaporative air chilling (EAC) on the moisture content, processing yield, surface color, and visual appearance of broiler carcasses. For the WC treatment, 1 group of birds was hard scalded and submersed into ice slush, whereas for AC, 1 group of birds was soft scalded and exposed to blowing air (1.0 m/s at 0°C) and for EAC, or 1 group of birds was soft scalded and exposed to blowing air and a cold water spray (every 5 min). During chilling, carcass temperature was reduced most effectively by WC (55 min), followed by EAC (120 min) and AC (155 min). After chilling, both WC and EAC carcasses picked up moisture at 4.6 and 1.0% of their weights, respectively, whereas AC carcasses lost 1.5% of their weight. On cutting at 5 h postmortem, WC carcasses showed the highest (2.5%), EAC showed the second highest (0.4%), and AC showed the least (0.3%) moisture loss. After 24 h of storage, almost 83% of the absorbed water in the WC carcass parts was released as purge, whereas EAC and AC carcasses maintained weights close to the prechilled weights. In an instrumental color evaluation and a visual evaluation by panelists, AC carcasses showed a darker appearance, a more yellow color, and more surface discoloration compared with WC or EAC carcasses.

  17. Study on lycopene and antioxidant contents variations in tomatoes under air-drying process.

    PubMed

    Chang, C-H; Liu, Y-C

    2007-11-01

    Effects of factors such as tomato cultivars, drying temperatures (40, 80, and 120 degrees C), and drying time (0 to 240 min) on tomato lycopene and the major antioxidant contents (MACs, herein as the sum of total phenolics and total flavonoids) during an air-drying process were investigated. The results showed that lycopene contents increased under all the drying temperatures during the first 60 min. However, the red tomato cultivars, that is, HR, SN, and TTL, exhibited a significant decrease in lycopene contents under 120 degrees C after drying for 75 min. According to the experimental data, an MAC threshold value of 500 mg/100 g dry matter of tomato is proposed. When the MAC is lower than this value during air-drying, lycopene contents in all tomato cultivars would drop rapidly. In addition, the tomatoes in yellow color group, containing more MACs initially and retaining more MACs under air-drying at 40 to 80 degrees C, are proposed to be the proper tomato cultivars for thermal processing.

  18. Evaluation of the Air Void Analyzer

    DTIC Science & Technology

    2013-07-01

    Criteria pavement design guidance for precise construction and the prevention of damage to asphalt pavements from heavy loads, extreme heat, spilt...cylinder specimen were tested following ASTM C39 (2005a) using a 440-kip capacity hydraulic load frame. Sulfur mortar caps were cast on the ends of the

  19. Climate and air quality trade-offs in altering ship fuel sulfur content

    NASA Astrophysics Data System (ADS)

    Partanen, A. I.; Laakso, A.; Schmidt, A.; Kokkola, H.; Kuokkanen, T.; Pietikäinen, J.-P.; Kerminen, V.-M.; Lehtinen, K. E. J.; Laakso, L.; Korhonen, H.

    2013-12-01

    Aerosol particles from shipping emissions both cool the climate and cause adverse health effects. The cooling effect is, however, declining because of shipping emission controls aiming to improve air quality. We used an aerosol-climate model ECHAM-HAMMOZ to test whether by altering ship fuel sulfur content, the present-day aerosol-induced cooling effect from shipping could be preserved, while at the same time reducing premature mortality rates related to shipping emissions. We compared the climate and health effects of a present-day shipping emission scenario (ship fuel sulfur content of 2.7%) with (1) a simulation with strict emission controls in the coastal waters (ship fuel sulfur content of 0.1%) and twofold the present-day fuel sulfur content (i.e. 5.4%) elsewhere; and (2) a scenario with global strict shipping emission controls (ship fuel sulfur content of 0.1% in coastal waters and 0.5% elsewhere) roughly corresponding to international agreements to be enforced by the year 2020. Scenario 1 had a slightly stronger aerosol-induced effective radiative forcing (ERF) from shipping than the present-day scenario (-0.43 W m-2 vs. -0.39 W m-2) while reducing premature mortality from shipping by 69% (globally 34 900 deaths avoided per year). Scenario 2 decreased the ERF to -0.06 W m-2 and annual deaths by 96% (globally 48 200 deaths avoided per year) compared to present-day. Our results show that the cooling effect of present-day emissions could be retained with simultaneous notable improvements in air quality, even though the shipping emissions from the open ocean clearly have a significant effect on continental air quality. However, increasing ship fuel sulfur content in the open ocean would violate existing international treaties, could cause detrimental side-effects, and could be classified as geoengineering.

  20. Comparison of void-measurement methods for carbon/epoxy composites. Final report

    SciTech Connect

    Ghiorse, S.R.

    1991-04-01

    This report studies four destructive measurement techniques for determining void volume fraction in CFRP composites. Two approaches to void measurement were taken: density determination/matrix digestion (DD/MD), and optical image analysis. Within each approach two techniques were studied. In the DD/MD approach, the water buoyancy technique WBY0 (see ASTM D 792) and density gradient technique (DGT) (see ASTM D 1505) were investigated. In the image analysis approach a Dapple Image Analyzer, and the more automated Omnimet Image Analyzer, techniques were investigated. It was found that true or absolute void content is quite difficult to measure regardless of the technique used. However, when making relative measurements between like specimens void content comparisons are reliable and practical to obtain. The WBT recorded consistently lower void content data than the DGT; it was also found to be less precise. For routine CFRP, void content determination, where relative comparisons are sufficient and high precision is not an issue, the WBT is recommended as it is practical to implement. When high precision is needed, the DGT is recommended. Image analysis methods produce highly localized data, but it is likely that they approximate true void content more closely than the DD/MD method because the void measurement, though actually a measure of void area, is direct. For more critical void content measurement where accuracy, as well as precision are required, a highly automated version of an image analysis technique, like the Omnimet, which scans a large number of cross sections is recommended. At present, this appears to be the best procedure available to determine true void content.

  1. Void Nucleation, Growth and Coalescence in Irradiated Metals

    SciTech Connect

    Surh, M P; Sturgeon, J B; Wolfer, W G

    2008-01-11

    A novel computational treatment of dense, stiff, coupled reaction rate equations is introduced to study the nucleation, growth, and possible coalescence of cavities during neutron irradiation of metals. Radiation damage is modeled by the creation of Frenkel pair defects and helium impurity atoms. A multi-dimensional cluster size distribution function allows independent evolution of the vacancy and helium content of cavities, distinguishing voids and bubbles. A model with sessile cavities and no cluster-cluster coalescence can result in a bimodal final cavity size distribution with coexistence of small, high-pressure bubbles and large, low-pressure voids. A model that includes unhindered cavity diffusion and coalescence ultimately removes the small helium bubbles from the system, leaving only large voids. The terminal void density is also reduced and the incubation period and terminal swelling rate can be greatly altered by cavity coalescence. Temperature-dependent trapping of voids/bubbles by precipitates and alterations in void surface diffusion from adsorbed impurities and internal gas pressure may give rise to intermediate swelling behavior through their effects on cavity mobility and coalescence.

  2. Survey of the Bootes void

    SciTech Connect

    Kirshner, R.P.; Oemler, A. Jr.; Schechter, P.L.; Shectman, S.A.

    1987-03-01

    In an earlier paper the authors inferred the existence of a void in the distribution of galaxies in the constellation of Bootes. In this paper, a redshift survey undertaken to test that hypothesis is described. Galaxies were selected by eye from 283 small fields distributed between the three original fields, and redshifts were measured for 239 of them. The existence of a large, roughly spherical void, of radius 62 Mpc, centered at alpha = 14 h 50, delta = + 46 deg, v = 15,500 km/s is confirmed. The low density of this region is of high statistical significance and does not appear easily reconcilable with any of the popular models for the growth of structure in the universe. This void does contain some unusual galaxies characterized by strong, high-excitation emission spectra, but not in sufficient numbers to compensate for the absence of more usual objects. 48 references.

  3. Estimation of Soil Moisture Content Using Air-Launched GPR Techniques in Variable Soil Conditions

    NASA Astrophysics Data System (ADS)

    Hardel, B.; Kelly, B.

    2008-12-01

    Air-launched Ground Penetrating Radar (GPR) techniques have most frequently been used for infrastructure characterization, but these techniques show promise for soil moisture estimation in the near subsurface. Air- launched GPR data can be acquired very quickly, and data processing can be easily automated, so these techniques have potential for efficient estimation of water content in the shallow subsurface over large areas. In this experiment, we investigate the efficacy of air-launched GPR techniques for estimating soil water content under saturated and dry conditions in both sandy and organic-rich soils. Data were also acquired to investigate the depth of penetration of air-launched data in these soils using multiple GPR frequencies. The experiment was performed in a large tank under controlled climatic conditions. Initially, the tank was filled with wet sand to a depth of 24-cm, and GPR data were acquired over the sand using 250-, 500-, and 1000-MHz antennas. Then, a thin plastic tarp was placed on the wet sand, a 3-cm layer of dry sand was placed on the tarp, and data collection was repeated. Additional 3-cm layers of dry sand were placed in the tank, with data acquisition after each layer, until the dry sand layer was 15-cm thick. The tank was then excavated, and a basal layer of dry sand was added. Data were again acquired over the dry sand, and the incremental filling of the tank and data acquisition were repeated using 3-cm layers of wet sand. Finally, the entire process was repeated using a basal layer of wet organic soil overlain by dry organic soil and using a basal layer of dry organic soil overlain by wet organic soil. For all air-launch data, the dielectric constant was determined using the amplitudes of the reflection from the soil surface, and Topp's equation was used to convert the dielectric constant to water content. Data analysis is ongoing, but preliminary results indicate that water content can be estimated with reasonable accuracy in both

  4. The influence of air content in water on ultrasonic cavitation field.

    PubMed

    Liu, Liyan; Yang, Yang; Liu, Penghong; Tan, Wei

    2014-03-01

    Cavitation is a complex physical phenomenon affected by many factors, one of which is the gas dissolved in the medium. Researchers have given some efforts to the influence of gas content on sonoluminescence or some specific chemical reactions in and around the bubble, but limited work has been reported about the influence on the ultrasonic cavitation field distribution. In this work, the intensity distribution of the ultrasound field in a cleaning tank has been measured with the hydrophone. After analysed and visualised by MATLAB software, it was found that the cavitation intensity distribution in degassed water was much better than that in tap water. And further study proved that degassing process can improve the cavitation effect dramatically both in intensity and scope. Finally, the cavitation fields in mediums with different gas content were measured and the specific influence of air content on cavitation field was discussed.

  5. Quantifying the distribution of paste-void spacing of hardened cement paste using X-ray computed tomography

    SciTech Connect

    Yun, Tae Sup; Kim, Kwang Yeom; Choo, Jinhyun; Kang, Dong Hun

    2012-11-15

    The distribution of paste-void spacing in cement-based materials is an important feature related to the freeze-thaw durability of these materials, but its reliable estimation remains an unresolved problem. Herein, we evaluate the capability of X-ray computed tomography (CT) for reliable quantification of the distribution of paste-void spacing. Using X-ray CT images of three mortar specimens having different air-entrainment characteristics, we calculate the distributions of paste-void spacing of the specimens by applying previously suggested methods for deriving the exact spacing of air-void systems. This methodology is assessed by comparing the 95th percentile of the cumulative distribution function of the paste-void spacing with spacing factors computed by applying the linear-traverse method to 3D air-void system and reconstructing equivalent air-void distribution in 3D. Results show that the distributions of equivalent void diameter and paste-void spacing follow lognormal and normal distributions, respectively, and the ratios between the 95th percentile paste-void spacing value and the spacing factors reside within the ranges reported by previous numerical studies. This experimental finding indicates that the distribution of paste-void spacing quantified using X-ray CT has the potential to be the basis for a statistical assessment of the freeze-thaw durability of cement-based materials. - Highlights: Black-Right-Pointing-Pointer The paste-void spacing in 3D can be quantified by X-ray CT. Black-Right-Pointing-Pointer The distribution of the paste-void spacing follows normal distribution. Black-Right-Pointing-Pointer The spacing factor and 95th percentile of CDF of paste-void spacing are correlated.

  6. Constraints on Cosmology and Gravity from the Dynamics of Voids

    NASA Astrophysics Data System (ADS)

    Hamaus, Nico; Pisani, Alice; Sutter, P. M.; Lavaux, Guilhem; Escoffier, Stéphanie; Wandelt, Benjamin D.; Weller, Jochen

    2016-08-01

    The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter, is attracted to these boundaries and causes voids to expand faster and to grow emptier over time. Using the distribution of galaxies centered on voids identified in the Sloan Digital Sky Survey and adopting minimal assumptions on the statistical motion of these galaxies, we constrain the average matter content Ωm=0.281 ±0.031 in the Universe today, as well as the linear growth rate of structure f /b =0.417 ±0.089 at median redshift z ¯=0.57 , where b is the galaxy bias (68% C.L.). These values originate from a percent-level measurement of the anisotropic distortion in the void-galaxy cross-correlation function, ɛ =1.003 ±0.012 , and are robust to consistency tests with bootstraps of the data and simulated mock catalogs within an additional systematic uncertainty of half that size. They surpass (and are complementary to) existing constraints by unlocking cosmological information on smaller scales through an accurate model of nonlinear clustering and dynamics in void environments. As such, our analysis furnishes a powerful probe of deviations from Einstein's general relativity in the low-density regime which has largely remained untested so far. We find no evidence for such deviations in the data at hand.

  7. Measurement of the muon content in air showers at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Veberič, Darko

    2016-07-01

    The muon content of extensive air showers produced by ultra-high energy cosmic rays is an observable sensitive to the composition of primary particles and to the properties of hadronic interactions governing the evolution of air-shower cascades. We present different methods for estimation of the number of muons at the ground and the muon production depth. These methods use measurements of the longitudinal, lateral, and temporal distribution of particles in air showers recorded by the detectors of the Pierre Auger Observatory. The results, obtained at about 140 TeV center-of-mass energy for proton primaries, are compared to the predictions of LHC-tuned hadronic-interaction models used in simulations with different primary masses. The models exhibit a deficitin the predicted muon content. The combination of these results with other independent mass composition analyses, such as those involving the depth of shower maximum observablemax, provide additional constraints on hadronic-interaction models for energies beyond the reach of the LHC.

  8. 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.

  9. Millennial and Sub-millennial Variability of Total Air Content from the WAIS Divide Ice Core

    NASA Astrophysics Data System (ADS)

    Edwards, Jon; Brook, Edward; Fegyveresi, John; Lee, James; Mitchell, Logan; Sowers, Todd; Alley, Richard; McConnell, Joe; Severinghaus, Jeff; Baggenstos, Daniel

    2014-05-01

    The analysis of ancient air bubbles trapped in ice is integral to the reconstruction of climate over the last 800 ka. While mixing ratios of greenhouse gases along with isotopic ratios are being studied in ever increasing resolution, one aspect of the gas record that continues to be understudied is the total air content (TAC) of the trapped bubbles. Published records of TAC are often too low in temporal resolution to adequately capture sub-millennial scale variability. Here we present a high-resolution TAC record (10-50 year sampling resolution) from the WAIS Divide ice core, measured at Oregon State and Penn State Universities. The records cover a variety of climatic conditions over the last 56 ka and show millennial variability of up to 10% and sub-millennial variability between 2.5 and 3.5%. We find that using the pore close off volume parameterization (Delomotte et al., J. Glaciology, 1999, v.45), along with the site temperature derived from isotopes, our TAC record implies unrealistically large changes in surface pressure or elevation. For example, the TAC decreases by ~10% between 19.5ka and 17.3ka, and would imply an elevation increase of nearly 800m. The total accumulation of ice over this period is just 280m (Fudge et al. Nature 2013), making the calculated elevation interpretation implausible. To resolve this discrepancy, we investigate the millennial and sub-millennial variability in our TAC record as a function of changes in firn densification and particularly layering. The firn is the uppermost layer of an ice sheet where snow is compressed into ice, trapping ancient air. Thus firn processes are important for the interpretation of total air content as well as other gas records. We compare our TAC record with proxies for dust, temperature and accumulation to determine how processes other than elevation affect TAC.

  10. Formation Of Voids In Dusty Lorentzian Plasma

    SciTech Connect

    Bahamida, S.; Annou, K.; Annou, R.

    2008-09-07

    We study the possibility of formation of voids in Lorentzian plasmas containing of dust particles obeying to vortex-like velocity distribution. The size of the void is found to be ion spectral index dependent.

  11. Testing the spherical evolution of cosmic voids

    NASA Astrophysics Data System (ADS)

    Demchenko, Vasiliy; Cai, Yan-Chuan; Heymans, Catherine; Peacock, John A.

    2016-11-01

    We study the spherical evolution model for voids in ΛCDM, where the evolution of voids is governed by dark energy at an earlier time than that for the whole universe or in overdensities. We show that the presence of dark energy suppresses the growth of peculiar velocities, causing void shell-crossing to occur at progressively later epochs as ΩΛ increases. We apply the spherical model to evolve the initial conditions of N-body simulated voids and compare the resulting final void profiles. We find that the model is successful in tracking the evolution of voids with radii greater than 30 h-1 Mpc, implying that void profiles could be used to constrain dark energy. We find that the initial peculiar velocities of voids play a significant role in shaping their evolution. Excluding the peculiar velocity in the evolution model delays the time of shell crossing.

  12. Climate and air quality trade-offs in altering ship fuel sulfur content

    NASA Astrophysics Data System (ADS)

    Partanen, A.-I.; Laakso, A.; Schmidt, A.; Kokkola, H.; Kuokkanen, T.; Pietikäinen, J.-P.; Kerminen, V.-M.; Lehtinen, K. E. J.; Laakso, L.; Korhonen, H.

    2013-08-01

    Aerosol particles from shipping emissions both cool the climate and cause adverse health effects. The cooling effect is, however, declining because of shipping emission controls aiming to improve air quality. We used an aerosol-climate model ECHAM-HAMMOZ to test whether by altering ship fuel sulfur content, the present-day aerosol-induced cooling effect from shipping could be preserved while at the same time reducing premature mortality rates related to shipping emissions. We compared the climate and health effects of a present-day shipping emission scenario with (1) a simulation with strict emission controls in the coastal waters (ship fuel sulfur content of 0.1%) and twofold ship fuel sulfur content compared to current global average of 2.7% elsewhere; and (2) a scenario with global strict shipping emission controls (ship fuel sulfur content of 0.1% in coastal waters and 0.5% elsewhere) roughly corresponding to international agreements to be enforced by the year 2020. Scenario 1 had a slightly stronger aerosol-induced radiative flux perturbation (RFP) from shipping than the present-day scenario (-0.43 W m-2 vs. -0.39 W m-2) while reducing premature mortality from shipping by 69% (globally 34 900 deaths avoided per year). Scenario 2 decreased the RFP to -0.06 W m-2 and annual deaths by 96% (globally 48 200 deaths avoided per year) compared to present-day. A small difference in radiative effect (global mean of 0.04 W m-2) in the coastal regions between Scenario 1 and the present-day scenario imply that shipping emission regulation in the existing emission control areas should not be removed in hope of climate cooling. Our results show that the cooling effect of present-day emissions could be retained with simultaneous notable improvements in air quality, even though the shipping emissions from the open ocean clearly have a significant effect on continental air quality. However, increasing ship fuel sulfur content in the open ocean would violate existing

  13. Manipulating ship fuel sulfur content and modeling the effects on air quality and climate

    NASA Astrophysics Data System (ADS)

    Partanen, Antti-Ilari; Laakso, Anton; Schmidt, Anja; Kokkola, Harri; Kuokkanen, Tuomas; Kerminen, Veli-Matti; Lehtinen, Kari E. J.; Laakso, Lauri; Korhonen, Hannele

    2013-04-01

    Aerosol emissions from international shipping are known to cause detrimental health effects on people mainly via increased lung cancer and cardiopulmonary diseases. On the other hand, the aerosol particles from the ship emissions modify the properties of clouds and are believed to have a significant cooling effect on the global climate. In recent years, aerosol emissions from shipping have been more strictly regulated in order to improve air quality and thus decrease the mortality due to ship emissions. Decreasing the aerosol emissions from shipping is projected to decrease their cooling effect, which would intensify the global warming even further. In this study, we use a global aerosol-climate model ECHAM5.5-HAM2 to test if continental air quality can be improved while still retaining the cooling effect from shipping. The model explicitly resolves emissions of aerosols and their pre-cursor gases. The model also calculates the interaction between aerosol particles and clouds, and can thus predict the changes in cloud properties due to aerosol emissions. We design and simulate a scenario where ship fuel sulfur content is strictly limited to 0.1% near all coastal regions, but doubled in the open oceans from the current global mean value of 2.7% (geo-ships). This scenario is compared to three other simulations: 1) No shipping emissions at all (no-ships), 2) present-day shipping emissions (std-ships) and 3) a future scenario where sulfur content is limited to 0.1% in the coastal zones and to 0.5% in the open ocean (future-ships). Global mean radiative flux perturbation (RFP) in std-ships compared to no-ships is calculated to be -0.4 W m-2, which is in the range of previous estimates for present-day shipping emissions. In the geo-ships simulation the corresponding global mean RFP is roughly equal, but RFP is spatially distributed more on the open oceans, as expected. In future-ships the decreased aerosol emissions provide weaker cooling effect of only -0.1 W m-2. In

  14. Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

    NASA Technical Reports Server (NTRS)

    Dominquez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

    2013-01-01

    Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

  15. Voids in the Large-Scale Structure

    NASA Astrophysics Data System (ADS)

    El-Ad, Hagai; Piran, Tsvi

    1997-12-01

    Voids are the most prominent feature of the large-scale structure of the universe. Still, their incorporation into quantitative analysis of it has been relatively recent, owing essentially to the lack of an objective tool to identify the voids and to quantify them. To overcome this, we present here the VOID FINDER algorithm, a novel tool for objectively quantifying voids in the galaxy distribution. The algorithm first classifies galaxies as either wall galaxies or field galaxies. Then, it identifies voids in the wall-galaxy distribution. Voids are defined as continuous volumes that do not contain any wall galaxies. The voids must be thicker than an adjustable limit, which is refined in successive iterations. In this way, we identify the same regions that would be recognized as voids by the eye. Small breaches in the walls are ignored, avoiding artificial connections between neighboring voids. We test the algorithm using Voronoi tesselations. By appropriate scaling of the parameters with the selection function, we apply it to two redshift surveys, the dense SSRS2 and the full-sky IRAS 1.2 Jy. Both surveys show similar properties: ~50% of the volume is filled by voids. The voids have a scale of at least 40 h-1 Mpc and an average -0.9 underdensity. Faint galaxies do not fill the voids, but they do populate them more than bright ones. These results suggest that both optically and IRAS-selected galaxies delineate the same large-scale structure. Comparison with the recovered mass distribution further suggests that the observed voids in the galaxy distribution correspond well to underdense regions in the mass distribution. This confirms the gravitational origin of the voids.

  16. A study of void effects on the interlaminar shear strength of unidirectional graphite fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Frimpong, Stephen

    1990-01-01

    A study was conducted to evaluate the effect of voids on the interlaminar shear strength (ILSS) of a polyimide matrix composite system. The graphite/PRM-15 composite was chosen for study because of the extensive amount of experience that has been amassed in the processing of this material. Composite densities and fiber contents of more than thirty different laminates were measured along with ILSS. Void contents were calculated and the void geometry and distribution were noted using microscopic techniques such as those used in metallography. It was found that there was a good empirical correlation between ILSS and composite density. The most acceptable relationship between the ILSS and density was found to be a power equation which closely resembles theoretically derived expressions. An increase in scatter in the strength data was observed as the void content increased. In laminates with low void content, the void appears to be more segregated in one area of the laminate. It was found that void free composites could be processed in matched metal die molds at pressures greater than 1.4 and less than 6.9 MPa.

  17. Void Growth and Coalescence Simulations

    DTIC Science & Technology

    2013-08-01

    AFRL-RW-EG-TR-2013-080 VOID GROWTH AND COALESCENCE SIMULATIONS Derek J. Reding 1 Pavol Stofko 2 Robert J. Dorgan 3 Michael E. Nixon 4...3002 W0AQ Derek J. Reding 1 Pavol Stofko 2 Robert J. Dorgan 3 Michael E. Nixon 4 1 Jacobs TEAS Team; 1030 Titan Court; Fort Walton Beach, FL 32547...on Steady-State Fluid Flow and Heat Transfer," Journal of Fluids Engineering, vol. 125, no. 4, pp. 731-733, 2003. [19] D. J. Reding and S. Hanagud

  18. Nocturia: The circadian voiding disorder

    PubMed Central

    Moon, Young Tae; Kim, Kyung Do

    2016-01-01

    Nocturia is a prevalent condition of waking to void during the night. The concept of nocturia has evolved from being a symptomatic aspect of disease associated with the prostate or bladder to a form of lower urinary tract disorder. However, recent advances in circadian biology and sleep science suggest that it might be important to consider nocturia as a form of circadian dysfunction. In the current review, nocturia is reexamined with an introduction to sleep disorders and recent findings in circadian biology in an attempt to highlight the importance of rediscovering nocturia as a problem of chronobiology. PMID:27195315

  19. Effects of laser and acid etching and air abrasion on mineral content of dentin.

    PubMed

    Malkoc, Meral Arslan; Taşdemir, Serife Tuba; Ozturk, A Nilgun; Ozturk, Bora; Berk, Gizem

    2011-01-01

    The aim of this study was to evaluate the mineral content of dentin prepared using an Er,Cr:YSGG laser at four different power settings, acid etching, and air abrasion. The study teeth comprised 35 molars which were randomly divided into seven equal groups. The occlusal third of the crowns were cut with a slow-speed diamond saw. The groups were as follows: group A, control group; group B, dentin etched with 35% buffered phosphoric acid for 30 s; group C, dentin abraded at 60 psi with 50-µm aluminium oxide for 1 s; groups D-G, dentin irradiated with the Er,Cr:YSGG laser at 1.50 W (group D), 2.25 W (group E), 3.00 W (group F), and 3.50 W (group G). The levels of Mg, P, Ca, K and Na in each dentin slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by one way analysis of variance and Tukey HSD tests. There were no significant differences between the groups in the levels of Ca, P and Na, and the Ca/P ratio (p>0.05); however, there were significant differences in the levels of K (p<0.001) and Mg (p=0.13). In addition, the levels of Mg in the air abrasion group were higher than in the other groups (p<0.01). Etching with the Er,Cr:YSGG laser system, air abrasion and acid etching did not affect the levels of Ca, P and Na, or the Ca/P ratio, in the dentin surface.

  20. The dark matter of galaxy voids

    NASA Astrophysics Data System (ADS)

    Sutter, P. M.; Lavaux, Guilhem; Wandelt, Benjamin D.; Weinberg, David H.; Warren, Michael S.

    2014-03-01

    How do observed voids relate to the underlying dark matter distribution? To examine the spatial distribution of dark matter contained within voids identified in galaxy surveys, we apply Halo Occupation Distribution models representing sparsely and densely sampled galaxy surveys to a high-resolution N-body simulation. We compare these galaxy voids to voids found in the halo distribution, low-resolution dark matter and high-resolution dark matter. We find that voids at all scales in densely sampled surveys - and medium- to large-scale voids in sparse surveys - trace the same underdensities as dark matter, but they are larger in radius by ˜20 per cent, they have somewhat shallower density profiles and they have centres offset by ˜ 0.4Rv rms. However, in void-to-void comparison we find that shape estimators are less robust to sampling, and the largest voids in sparsely sampled surveys suffer fragmentation at their edges. We find that voids in galaxy surveys always correspond to underdensities in the dark matter, though the centres may be offset. When this offset is taken into account, we recover almost identical radial density profiles between galaxies and dark matter. All mock catalogues used in this work are available at http://www.cosmicvoids.net.

  1. Cosmology with void-galaxy correlations.

    PubMed

    Hamaus, Nico; Wandelt, Benjamin D; Sutter, P M; Lavaux, Guilhem; Warren, Michael S

    2014-01-31

    Galaxy bias, the unknown relationship between the clustering of galaxies and the underlying dark matter density field is a major hurdle for cosmological inference from large-scale structure. While traditional analyses focus on the absolute clustering amplitude of high-density regions mapped out by galaxy surveys, we propose a relative measurement that compares those to the underdense regions, cosmic voids. On the basis of realistic mock catalogs we demonstrate that cross correlating galaxies and voids opens up the possibility to calibrate galaxy bias and to define a static ruler thanks to the observable geometric nature of voids. We illustrate how the clustering of voids is related to mass compensation and show that volume-exclusion significantly reduces the degree of stochasticity in their spatial distribution. Extracting the spherically averaged distribution of galaxies inside voids from their cross correlations reveals a remarkable concordance with the mass-density profile of voids.

  2. Constraints on Cosmology and Gravity from the Dynamics of Voids.

    PubMed

    Hamaus, Nico; Pisani, Alice; Sutter, P M; Lavaux, Guilhem; Escoffier, Stéphanie; Wandelt, Benjamin D; Weller, Jochen

    2016-08-26

    The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter, is attracted to these boundaries and causes voids to expand faster and to grow emptier over time. Using the distribution of galaxies centered on voids identified in the Sloan Digital Sky Survey and adopting minimal assumptions on the statistical motion of these galaxies, we constrain the average matter content Ω_{m}=0.281±0.031 in the Universe today, as well as the linear growth rate of structure f/b=0.417±0.089 at median redshift z[over ¯]=0.57, where b is the galaxy bias (68% C.L.). These values originate from a percent-level measurement of the anisotropic distortion in the void-galaxy cross-correlation function, ϵ=1.003±0.012, and are robust to consistency tests with bootstraps of the data and simulated mock catalogs within an additional systematic uncertainty of half that size. They surpass (and are complementary to) existing constraints by unlocking cosmological information on smaller scales through an accurate model of nonlinear clustering and dynamics in void environments. As such, our analysis furnishes a powerful probe of deviations from Einstein's general relativity in the low-density regime which has largely remained untested so far. We find no evidence for such deviations in the data at hand.

  3. Voids in cosmological simulations over cosmic time

    NASA Astrophysics Data System (ADS)

    Wojtak, Radosław; Powell, Devon; Abel, Tom

    2016-06-01

    We study evolution of voids in cosmological simulations using a new method for tracing voids over cosmic time. The method is based on tracking watershed basins (contiguous regions around density minima) of well-developed voids at low redshift, on a regular grid of density field. It enables us to construct a robust and continuous mapping between voids at different redshifts, from initial conditions to the present time. We discuss how the new approach eliminates strong spurious effects of numerical origin when voids' evolution is traced by matching voids between successive snapshots (by analogy to halo merger trees). We apply the new method to a cosmological simulation of a standard Λ-cold-dark-matter cosmological model and study evolution of basic properties of typical voids (with effective radii 6 h-1 Mpc < Rv < 20 h-1 Mpc at redshift z = 0) such as volumes, shapes, matter density distributions and relative alignments. The final voids at low redshifts appear to retain a significant part of the configuration acquired in initial conditions. Shapes of voids evolve in a collective way which barely modifies the overall distribution of the axial ratios. The evolution appears to have a weak impact on mutual alignments of voids implying that the present state is in large part set up by the primordial density field. We present evolution of dark matter density profiles computed on isodensity surfaces which comply with the actual shapes of voids. Unlike spherical density profiles, this approach enables us to demonstrate development of theoretically predicted bucket-like shape of the final density profiles indicating a wide flat core and a sharp transition to high-density void walls.

  4. Acoustic absorption modeling of porous concrete considering the gradation and shape of aggregates and void ratio

    NASA Astrophysics Data System (ADS)

    Kim, H. K.; Lee, H. K.

    2010-03-01

    The results of acoustic absorption modeling of porous concrete considering the gradation and shape of aggregates and void ratio are presented. To model the void texture of porous concrete, the multi-layered micro-perforated rigid panel model considering air gaps [1,2] is adopted. The parameters used in this acoustic absorption modeling are determined by a geometrical and experimental approach considering the gradation and shape of aggregates and void ratio. The predicted acoustic absorption spectra are compared with experimental results to verify the proposed acoustic absorption modeling approach. Finally, a parametric study is conducted to investigate the influence of design factors on the acoustic absorption properties of porous concrete.

  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. Impact of sulfur content regulations of shipping fuel on coastal air quality

    NASA Astrophysics Data System (ADS)

    Seyler, André; Wittrock, Folkard; Kattner, Lisa; Mathieu-Üffing, Barbara; Weigelt, Andreas; Peters, Enno; Richter, Andreas; Schmolke, Stefan; Burrows, John P.

    2016-04-01

    Shipping traffic is a sector that faces an enormous growth rate and contributes substantially to the emissions from the transportation sector, but lacks regulations and controls. Shipping is not enclosed in the Kyoto Protocol. However, the International Maritime Organization (IMO) introduced sufhur limits for marine heavy fuels, nitrogen oxide limits for newly-built ship engines and established Emission Control Areas (ECA) in the North and Baltic Sea as well as around North America with the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78 Annex VI). Recently, on the 1st of January 2015, the allowed sulfur content of marine fuels inside Sulfur Emission Control Areas has been significantly decreased from 1.0% to 0.1%. However, measurements of reactive trace gases and the chemical composition of the marine troposphere along shipping routes are sparse and up to now there is no regular monitoring system available. The project MeSmarT (measurements of shipping emissions in the marine troposphere) is a cooperation between the University of Bremen, the German Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and the Helmholtz-Zentrum Geesthacht. This study aims to analyse the influence of shipping emissions on the coastal air quality by evaluating ground-based remote sensing measurements using the MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) technique. Measurements of the atmospheric trace gases nitrogen dioxide (NO2) and sulfur dioxide (SO2) have been carried out in the marine troposphere at the MeSmarT measurement sites in Wedel and on Neuwerk and on-board several ship cruises on the North and Baltic Sea. The capability of two-channel MAX-DOAS systems to do simultaneous measurements in the UV and visible spectral range has been used in the so called "onion-peeling" approach to derive spatial distributions of ship emissions and to analyse the movement of the exhausted

  7. Use of electrical resistivity to detect underground mine voids in Ohio

    USGS Publications Warehouse

    Sheets, Rodney A.

    2002-01-01

    Electrical resistivity surveys were completed at two sites along State Route 32 in Jackson and Vinton Counties, Ohio. The surveys were done to determine whether the electrical resistivity method could identify areas where coal was mined, leaving air- or water-filled voids. These voids can be local sources of potable water or acid mine drainage. They could also result in potentially dangerous collapse of roads or buildings that overlie the voids. The resistivity response of air- or water-filled voids compared to the surrounding bedrock may allow electrical resistivity surveys to delineate areas underlain by such voids. Surface deformation along State Route 32 in Jackson County led to a site investigation, which included electrical resistivity surveys. Several highly resistive areas were identified using axial dipole-dipole and Wenner resistivity surveys. Subsequent drilling and excavation led to the discovery of several air-filled abandoned underground mine tunnels. A site along State Route 32 in Vinton County, Ohio, was drilled as part of a mining permit application process. A mine void under the highway was instrumented with a pressure transducer to monitor water levels. During a period of high water level, electrical resistivity surveys were completed. The electrical response was dominated by a thin, low-resistivity layer of iron ore above where the coal was mined out. Nearby overhead powerlines also affected the results.

  8. Piezoelectric performance of fluor polymer sandwiches with different void structures

    NASA Astrophysics Data System (ADS)

    Lou, Kexing; Zhang, Xiaoqing; Xia, Zhongfu

    2012-06-01

    Film sandwiches, consisting of two outer layers of fluoroethylenepropylene and one middle layer of patterned porous polytetrafluoroethylene, were prepared by patterning and fusion bonding. Contact charging was conducted to render the films piezoelectric. The critical voltage to trigger air breakdown in the inner voids in the fabricated films was investigated. The piezoelectric d 33 coefficients were measured employing the quasistatic method and dielectric resonance spectrum. The results show that the critical voltage for air breakdown in the inner voids is associated with the void microstructure of the films. For the films with patterning factors of 0%, 25% and 44%, the critical values are 300, 230 and 230 kV/cm, respectively. With an increase in the patterning factor, both the piezoelectric d 33 coefficients determined from the dielectric resonance spectra and those determined from quasistatic measurements increase, which might be due to a decrease in Young's modulus for the films. The nonlinearity of d 33 becomes increasingly obvious as the patterning factor increases.

  9. Mineral content of urban plants as an indicator of air sulphate pollution

    SciTech Connect

    Ufimtseva, M.D.; Zaickina, L.I.

    1996-08-01

    Phytogeochemical indication constitutes one of the promising methods of urban environment monitoring. Usually the phytogeochemical assessment includes the estimation of heavy metal content in urban plants in reference to the regional background level. The indication, based on the diversity of the biological response reactions to the industrial contamination, allows us to use the other parameters for the characterization of current condition of the urban environment (and particularly the atmospheric contamination) as well. As it is well known, mineral phytolites which may constitute up to 85% of dry weight are formed in plant tissues. The mineral composition of plants does not seem to be studied well enough as yet, and the data on mineral complexes in urban plants are absent completely. The authors` attempt was to study the peculiarities of urban plant mineral content and to reveal the value of the quantitative proportion of different mineral compounds for the air pollution indication. Urban plant mineral composition was tested in the samples of ashes by means of the infrared (IR) spectroscopy method which is usually used for the estimation of mineral compounds in rock. The IR absorption spectra were taken for the samples of bark or leaf ashes, taken from the tree, shrub, and herbaceous species that were most common and widely distributed both throughout the industrial areas and in the areas without noticeable pollution. These spectra look like curves with a lot of peales with different range which evidently correspond not to clear substances but to the mixtures of different minerals. The variation of absorbtion intensities in the observed lands makes it possible to estimate the quantitative contribution of different minerals (carbonates, sulphates, phosphates, quartz, feldspar, etc.) to the general IR spectrum.

  10. What Health-Related Information Flows through You Every Day? A Content Analysis of Microblog Messages on Air Pollution

    ERIC Educational Resources Information Center

    Yang, Qinghua; Yang, Fan; Zhou, Chun

    2015-01-01

    Purpose: The purpose of this paper is to investigate how the information about haze, a term used in China to describe the air pollution problem, is portrayed on Chinese social media by different types of organizations using the theoretical framework of the health belief model (HBM). Design/methodology/approach: A content analysis was conducted…

  11. [Research on accurate measurement of oxygen content in coal using laser-induced breakdown spectroscopy in air environment].

    PubMed

    Yin, Wang-bao; Zhang, Lei; Wang, Le; Dong, Lei; Ma, Wei-guang; Jia, Suo-tang

    2012-01-01

    A technique about accurate measurement of oxygen content in coal in air environment using laser-induced breakdown spectroscopy (LIBS) is introduced in the present paper. Coal samples were excited by the laser, and plasma spectra were obtained. Combining internal standard method, temperature correction method and multi-line methods, the oxygen content of coal samples was precisely measured. The measurement precision is not less than 1.37% for oxygen content in coal analysis, so is satisfied for the requirement of coal-fired power plants in coal analysis. This method can be used in surveying, environmental protection, medicine, materials, archaeological and food safety, biochemical and metallurgy application.

  12. Anthropogenic and naturally occurring radionuclide content in near surface air in Cáceres (Spain).

    PubMed

    Baeza, Antonio; Rodríguez-Perulero, Antonio; Guillén, Javier

    2016-12-01

    The anthropogenic ((137)Cs, (90)Sr, (239+240)Pu and (241)Am) and naturally occurring radionuclide ((40)K, (234,238)U, (228,230,232)Th, (226)Ra and (210)Pb) content in near surface air present seasonal variations related to natural processes, such as soil erosion, resuspension of fine particles of soil and radon exhalation from soil ((210)Pb). The objective is to analyze seasonal variations of their concentrations and compare with radiological events (Fukushima fallout and wild fire) in a location without any known source of anthropogenic radionuclides. The (210)Pb, (40)K, and (137)Cs presented annual variations, with maximum activity levels in summer. Solar radiation and rainfall were correlated with (210)Pb and (40)K. The (234,238)U, (228,230,232)Th, (226)Ra, (137)Cs and (90)Sr presented positive correlation with monthly mean values of temperature. The ratio (90)Sr/(137)Cs was within the range of those reported for soils in Spain. Finally, the maximal effective dose rate was estimated to be 37 and 88 μSv/y for infants and adults, respectively, well below 1 mSv/y reference level. The main contributor to effective dose was (210)Pb, about 92%, followed by: (210)Pb ≫ (228,230,232)Th > (226)Ra, (234,238)U > (7)Be, (239+240)Pu > (40)K, (90)Sr > (137)Cs > (22)Na.

  13. Alignment of voids in the cosmic web

    NASA Astrophysics Data System (ADS)

    Platen, Erwin; van de Weygaert, Rien; Jones, Bernard J. T.

    2008-06-01

    We investigate the shapes and mutual alignment of voids in the large-scale matter distribution of a Λ cold dark matter (ΛCDM) cosmology simulation. The voids are identified using the novel watershed void finder (WVF) technique. The identified voids are quite non-spherical and slightly prolate, with axis ratios in the order of c:b:a ~ 0.5:0.7:1. Their orientations are strongly correlated with significant alignments spanning scales >30h-1Mpc. We also find an intimate link between the cosmic tidal field and the void orientations. Over a very wide range of scales we find a coherent and strong alignment of the voids with the tidal field computed from the smoothed density distribution. This orientation-tide alignment remains significant on scales exceeding twice the typical void size, which shows that the long-range external field is responsible for the alignment of the voids. This confirms the view that the large-scale tidal force field is the main agent for the large-scale spatial organization of the cosmic web.

  14. Void fraction prediction in subchannel geometry

    SciTech Connect

    Khan, H.J.; Kosaly, G.

    1986-01-01

    Two-phase flow void fraction calculation via drift flux formulation requires specific correlations for the distribution parameter, C/sub 0/, and the vapor drift velocity, V/sub gj/. The void fraction may then be calculated from Zuber-Findlay's void-quality model. The distribution parameter is defined using void and flow distributions. Different correlations for C/sub 0/ are available for bundle-averaged void fraction calculation. Yet no such correlations have been developed for subchannel void fraction calculation. The aim of this summary is to demonstrate the results of subchannel void fraction calculation obtained from the model developed here. The three-dimensional subchannel drift flux code CANAL has been used in the present analysis to perform the calculations. The code uses four conservation equations, which include liquid and vapor continuity equations in addition to mixture momentum and energy equations. The subchannel mass flux and quality prediction capability of CANAL has already been demonstrated for a wide range of experiments. Therefore, with the use of appropriate drift flux parameters, subchannel void fractions can be calculated by CANAL.

  15. Statistics and geometry of cosmic voids

    SciTech Connect

    Gaite, José

    2009-11-01

    We introduce new statistical methods for the study of cosmic voids, focusing on the statistics of largest size voids. We distinguish three different types of distributions of voids, namely, Poisson-like, lognormal-like and Pareto-like distributions. The last two distributions are connected with two types of fractal geometry of the matter distribution. Scaling voids with Pareto distribution appear in fractal distributions with box-counting dimension smaller than three (its maximum value), whereas the lognormal void distribution corresponds to multifractals with box-counting dimension equal to three. Moreover, voids of the former type persist in the continuum limit, namely, as the number density of observable objects grows, giving rise to lacunar fractals, whereas voids of the latter type disappear in the continuum limit, giving rise to non-lacunar (multi)fractals. We propose both lacunar and non-lacunar multifractal models of the cosmic web structure of the Universe. A non-lacunar multifractal model is supported by current galaxy surveys as well as cosmological N-body simulations. This model suggests, in particular, that small dark matter halos and, arguably, faint galaxies are present in cosmic voids.

  16. Modeling void abundance in modified gravity

    NASA Astrophysics Data System (ADS)

    Voivodic, Rodrigo; Lima, Marcos; Llinares, Claudio; Mota, David F.

    2017-01-01

    We use a spherical model and an extended excursion set formalism with drifting diffusive barriers to predict the abundance of cosmic voids in the context of general relativity as well as f (R ) and symmetron models of modified gravity. We detect spherical voids from a suite of N-body simulations of these gravity theories and compare the measured void abundance to theory predictions. We find that our model correctly describes the abundance of both dark matter and galaxy voids, providing a better fit than previous proposals in the literature based on static barriers. We use the simulation abundance results to fit for the abundance model free parameters as a function of modified gravity parameters, and show that counts of dark matter voids can provide interesting constraints on modified gravity. For galaxy voids, more closely related to optical observations, we find that constraining modified gravity from void abundance alone may be significantly more challenging. In the context of current and upcoming galaxy surveys, the combination of void and halo statistics including their abundances, profiles and correlations should be effective in distinguishing modified gravity models that display different screening mechanisms.

  17. Effects of Ag on the Kirkendall void formation of Sn-xAg/Cu solder joints

    NASA Astrophysics Data System (ADS)

    Kim, Sunghwan; Yu, Jin

    2010-10-01

    Binary Sn-Ag solders with varying amounts of Ag (0.5, 2.0, and 3.5 wt %) were reacted with Cu under bump metallurgy (UBM) which was electroplated with bis-sodium sulfopropyl-disulfide additive, and the characteristics of Kirkendall void formation at the solder joints were investigated. The results indicate that the propensity to form Kirkendall voids at the solder joint decreased with the Ag content. Subsequent Auger electron spectroscopy analyses showed that Ag dissolved in the Cu UBM reduced the segregation of S to the Cu3Sn/Cu interface, which suppressed the nucleation of Kirkendall voids at the interface.

  18. Void percolation and conduction of overlapping ellipsoids.

    PubMed

    Yi, Y B

    2006-09-01

    The void percolation and conduction problems for equisized overlapping ellipsoids of revolution are investigated using the discretization method. The method is validated by comparing the estimated percolation threshold of spheres with the precise result found in literature. The technique is then extended to determine the threshold of void percolation as a function of the geometric aspect ratio of ellipsoidal particles. The finite element method is also applied to evaluate the equivalent conductivity of the void phase in the system. The results confirm that there are no universalities for void percolation threshold and conductivity in particulate systems, and these properties are clearly dependent on the geometrical shape of particles. As a consequence, void percolation and conduction associated with ellipsoidal particles of large aspect ratio should be treated differently from spheres.

  19. Emissions of industrial furnaces burning diesel fuel oils of various sulfur contents with NaCl - contained atmospheric air

    SciTech Connect

    Lin, C.Y.; Hsieh, M.J.

    1996-04-01

    A small furnace associated with an industrial automatic burner was employed in this study to investigate the influences of sulfur content of fuel oils burned with NaCl contained atmospheric air on the emission characteristics of marine or industrial power-plants. The sulfur contents of 0.3 wt% and 1.0 wt% were considered. Diesel fuel oil A which approximates ASTM No. 2 fuel oil was atomized by the inlet air added with NaCl of 1.5 ppm concentration and thereafter burned within the furnace. It was found that under this burning condition the CO, SO{sub 2}, and O{sub 2} emissions increased with the addition of sulfur in the fuel oil. However, the gas temperature and NO{sub x} concentration were affected by the increase of sulfur content to only a minor extent. 14 refs., 10 figs.

  20. Observation of voids and optical seizing of voids in silica glass with infrared femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Watanabe, Wataru; Toma, Tadamasa; Yamada, Kazuhiro; Nishii, Junji; Hayashi, Ken-ichi; Itoh, Kazuyoshi

    2000-11-01

    Many researchers have investigated the interaction of femtosecond laser pulses with a wide variety of materials. The structural modifications both on the surface and inside the bulk of transparent materials have been demonstrated. When femtosecond laser pulses are focused into glasses with a high numerical-aperture objective, voids are formed. We demonstrate that one can seize and move voids formed by femtosecond laser pulses inside silica glass and also merge two voids into one. We also present clear evidence that a void is a cavity by showing a scanning-electron-microscope image of cleft voids: we clove through the glass along a plane that includes the laser-ablated thin line on the surface and the voids formed inside. The optical seizing and merging of voids are important basic techniques for fabricate micro-optical dynamic devices, such as the rewritable 3-D optical storage.

  1. Interfacial area, velocity and void fraction in two-phase slug flow

    SciTech Connect

    Kojasoy, G.; Riznic, J.R.

    1997-12-31

    The internal flow structure of air-water plug/slug flow in a 50.3 mm dia transparent pipeline has been experimentally investigated by using a four-sensor resistivity probe. Liquid and gas volumetric superficial velocities ranged from 0.55 to 2.20 m/s and 0.27 to 2.20 m/s, respectively, and area-averaged void fractions ranged from about 10 to 70%. The local distributions of void fractions, interfacial area concentration and interface velocity were measured. Contributions from small spherical bubbles and large elongated slug bubbles toward the total void fraction and interfacial area concentration were differentiated. It was observed that the small bubble void contribution to the overall void fraction was small indicating that the large slug bubble void fraction was a dominant factor in determining the total void fraction. However, the small bubble interfacial area contribution was significant in the lower and upper portions of the pipe cross sections.

  2. Cosmic voids and void lensing in the Dark Energy Survey science verification data

    SciTech Connect

    Sánchez, C.; Clampitt, J.; Kovacs, A.; Jain, B.; García-Bellido, J.; Nadathur, S.; Gruen, D.; Hamaus, N.; Huterer, D.; Vielzeuf, P.; Amara, A.; Bonnett, C.; DeRose, J.; Hartley, W. G.; Jarvis, M.; Lahav, O.; Miquel, R.; Rozo, E.; Rykoff, E. S.; Sheldon, E.; Wechsler, R. H.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Krause, E.; Kuehn, K.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Melchior, P.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Walker, A. R.; Weller, J.

    2016-10-26

    Galaxies and their dark matter halos populate a complicated filamentary network around large, nearly empty regions known as cosmic voids. Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of ~50 Mpc/h or more that can render many voids undetectable. In this paper we present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-z redMaGiC galaxy sample of the Dark Energy Survey Science Verification (DES-SV) data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo- z scatter, the number of voids found in these projected slices of simulated spectroscopic and photometric galaxy catalogs is within 20% for all transverse void sizes, and indistinguishable for the largest voids of radius ~70 Mpc/h and larger. The positions, radii, and projected galaxy profiles of photometric voids also accurately match the spectroscopic void sample. Applying the algorithm to the DES-SV data in the redshift range 0.2 < z < 0.8 , we identify 87 voids with comoving radii spanning the range 18-120 Mpc/h, and carry out a stacked weak lensing measurement. With a significance of 4.4σ, the lensing measurement confirms the voids are truly underdense in the matter field and hence not a product of Poisson noise, tracer density effects or systematics in the data. In conclusion, it also demonstrates, for the first time in real data, the viability of void lensing studies in photometric surveys.

  3. Cosmic voids and void lensing in the Dark Energy Survey Science Verification data

    SciTech Connect

    Sánchez, C.; Clampitt, J.; Kovacs, A.; Jain, B.; García-Bellido, J.; Nadathur, S.; Gruen, D.; Hamaus, N.; Huterer, D.; Vielzeuf, P.; Amara, A.; Bonnett, C.; DeRose, J.; Hartley, W. G.; Jarvis, M.; Lahav, O.; Miquel, R.; Rozo, E.; Rykoff, E. S.; Sheldon, E.; Wechsler, R. H.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Krause, E.; Kuehn, K.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Melchior, P.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Walker, A. R.; Weller, J.

    2016-10-26

    Galaxies and their dark matter halos populate a complicated filamentary network around large, nearly empty regions known as cosmic voids. Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of $\\sim50$ Mpc/$h$ or more that can render many voids undetectable. In this paper we present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-$z$ redMaGiC galaxy sample of the Dark Energy Survey Science Verification (DES-SV) data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo-$z$ scatter, the number of voids found in these projected slices of simulated spectroscopic and photometric galaxy catalogs is within 20% for all transverse void sizes, and indistinguishable for the largest voids of radius $\\sim 70$ Mpc/$h$ and larger. The positions, radii, and projected galaxy profiles of photometric voids also accurately match the spectroscopic void sample. Applying the algorithm to the DES-SV data in the redshift range $0.2voids with comoving radii spanning the range 18-120 Mpc/$h$, and carry out a stacked weak lensing measurement. With a significance of $4.4\\sigma$, the lensing measurement confirms the voids are truly underdense in the matter field and hence not a product of Poisson noise, tracer density effects or systematics in the data. It also demonstrates, for the first time in real data, the viability of void lensing studies in photometric surveys.

  4. A proposed measurement method for void fraction in lubricant oil based on the image processing technique.

    PubMed

    Wang, Jianwen; An, Qi

    2008-02-01

    A new method for measuring void fraction in lubricating oils is presented based on the image processing technique. The problem here differs from the bubbles detection problem in two-phase fluids in that our interest lies in the gross amount of gas voids in oils. Our method is based on an observation that gas voids in oils change the color of the mixed gas-oil material. Therefore, a measurement technique was established based on the change in color. In particular, the relationship between the change in color and amount of voids was established experimentally. The experiment and testing were performed on a particular setup which consists of a pipe, oil, and air. The test result has shown that this method is effective. The method is the simplest and most accurate one among the existing methods.

  5. Cosmic voids and void lensing in the Dark Energy Survey Science Verification data

    NASA Astrophysics Data System (ADS)

    Sánchez, C.; Clampitt, J.; Kovacs, A.; Jain, B.; García-Bellido, J.; Nadathur, S.; Gruen, D.; Hamaus, N.; Huterer, D.; Vielzeuf, P.; Amara, A.; Bonnett, C.; DeRose, J.; Hartley, W. G.; Jarvis, M.; Lahav, O.; Miquel, R.; Rozo, E.; Rykoff, E. S.; Sheldon, E.; Wechsler, R. H.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Krause, E.; Kuehn, K.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Melchior, P.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Walker, A. R.; Weller, J.; DES Collaboration

    2017-02-01

    Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of ≥50 Mpc h-1which can render many voids undetectable. We present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-z redMaGiC galaxy sample of the DES Science Verification data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo-z scatter, the number of voids found in simulated spectroscopic and photometric galaxy catalogues is within 20 per cent for all transverse void sizes, and indistinguishable for the largest voids (Rv ≥ 70 Mpc h-1). The positions, radii, and projected galaxy profiles of photometric voids also accurately match the spectroscopic void sample. Applying the algorithm to the DES-SV data in the redshift range 0.2 < z < 0.8, we identify 87 voids with comoving radii spanning the range 18-120 Mpc h-1, and carry out a stacked weak lensing measurement. With a significance of 4.4σ, the lensing measurement confirms that the voids are truly underdense in the matter field and hence not a product of Poisson noise, tracer density effects or systematics in the data. It also demonstrates, for the first time in real data, the viability of void lensing studies in photometric surveys.

  6. Neutron Imaging Calibration to Measure Void Fraction

    SciTech Connect

    Geoghegan, Patrick J; Bilheux, Hassina Z; Sharma, Vishaldeep; Fricke, Brian A

    2015-01-01

    Void fraction is an intuitive parameter that describes the fraction of vapor in a two-phase flow. It appears as a key variable in most heat transfer and pressure drop correlations used to design evaporating and condensing heat exchangers, as well as determining charge inventory in refrigeration systems. Void fraction measurement is not straightforward, however, and assumptions on the invasiveness of the measuring technique must be made. Neutron radiography or neutron imaging has the potential to be a truly non-invasive void fraction measuring technique but has until recently only offered qualitative descriptions of two-phase flow, in terms of flow maldistributions, for example. This paper describes the calibration approach necessary to employ neutron imaging to measure steady-state void fraction. Experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA.

  7. Effects of a Circulating-water Garment and Forced-air Warming on Body Heat Content and Core Temperature

    PubMed Central

    Taguchi, Akiko; Ratnaraj, Jebadurai; Kabon, Barbara; Sharma, Neeru; Lenhardt, Rainer; Sessler, Daniel I.

    2005-01-01

    Background: Forced-air warming is sometimes unable to maintain perioperative normothermia. We therefore compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. Methods: Nine volunteers were each evaluated on two randomly ordered study days. They were anesthetized and cooled to a core temperature near 34°C. The volunteers were subsequently warmed for 2.5 hours with either a circulating-water garment or forced-air cover. Overall, heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 18 intramuscular needle thermocouples, 15 skin thermal flux transducers, and “deep” arm and foot thermometers. Results: Heat production (≈ 60 kcal/h) and loss (≈45 kcal/h) were similar with each treatment before warming. The increase in heat transfer across anterior portions of the skin surface was similar with each warming system (≈65 kcal/h). Forced-air warming had no effect on posterior heat transfer whereas circulating-water transferred 21 ± 9 kcal/h through the posterior skin surface after a half hour of warming. Over 2.5 h, circulating-water thus increased body heat content 56% more than forced air. Core temperatures thus increased faster than with circulating water than forced air, especially during the first hour, with the result that core temperature was 1.1 ± 0.7°C greater after 2.5 h (P < 0.001). Peripheral tissue heat content increased twice as much as core heat content with each device, but the core-to-peripheral tissue temperature gradient remained positive throughout the study. Conclusions: The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4°C/h faster than forced air. A substantial peripheral

  8. Void Profile from Planck Lensing Potential Map

    NASA Astrophysics Data System (ADS)

    Chantavat, Teeraparb; Sawangwit, Utane; Wandelt, Benjamin D.

    2017-02-01

    We use the lensing potential map from Planck CMB lensing reconstruction analysis and the “Public Cosmic Void Catalog” to measure the stacked void lensing potential. We have made an attempt to fit the HSW void profile parameters from the stacked lensing potential. In this profile, four parameters are needed to describe the shape of voids with different characteristic radii R V . However, we have found that after reducing the background noise by subtracting the average background, there is a residue lensing power left in the data. The inclusion of the environment shifting parameter, {γ }V, is necessary to get a better fit to the data with the residue lensing power. We divide the voids into two redshift bins: cmass1 (0.45< z< 0.5) and cmass2 (0.5< z< 0.6). Our best-fit parameters are α =1.989+/- 0.149, β =12.61+/- 0.56, {δ }c=-0.697+/- 0.025, {R}S/{R}V=1.039+/- 0.030, {γ }v=(-7.034+/- 0.150)× {10}-2 for the cmass1 sample with 123 voids and α =1.956+/- 0.165, β =12.91+/- 0.60, {δ }c=-0.673+/- 0.027, {R}S/{R}V=1.115+/- 0.032, {γ }v=(-4.512+/- 0.114)× {10}-2 for the cmass2 sample with 393 voids at 68% C.L. The addition of the environment shifting parameter is consistent with the conjecture that the Sloan Digital Sky Survey voids reside in an underdense region.

  9. Prenatal Ambient Air Pollution, Placental Mitochondrial DNA Content, and Birth Weight in the INMA (Spain) and ENVIRONAGE (Belgium) Birth Cohorts

    PubMed Central

    Clemente, Diana B.P.; Casas, Maribel; Vilahur, Nadia; Begiristain, Haizea; Bustamante, Mariona; Carsin, Anne-Elie; Fernández, Mariana F.; Fierens, Frans; Gyselaers, Wilfried; Iñiguez, Carmen; Janssen, Bram G.; Lefebvre, Wouter; Llop, Sabrina; Olea, Nicolás; Pedersen, Marie; Pieters, Nicky; Santa Marina, Loreto; Souto, Ana; Tardón, Adonina; Vanpoucke, Charlotte; Vrijheid, Martine; Sunyer, Jordi; Nawrot, Tim S.

    2015-01-01

    Background: Mitochondria are sensitive to environmental toxicants due to their lack of repair capacity. Changes in mitochondrial DNA (mtDNA) content may represent a biologically relevant intermediate outcome in mechanisms linking air pollution and fetal growth restriction. Objective: We investigated whether placental mtDNA content is a possible mediator of the association between prenatal nitrogen dioxide (NO2) exposure and birth weight. Methods: We used data from two independent European cohorts: INMA (n = 376; Spain) and ENVIRONAGE (n = 550; Belgium). Relative placental mtDNA content was determined as the ratio of two mitochondrial genes (MT-ND1 and MTF3212/R3319) to two control genes (RPLP0 and ACTB). Effect estimates for individual cohorts and the pooled data set were calculated using multiple linear regression and mixed models. We also performed a mediation analysis. Results: Pooled estimates indicated that a 10-μg/m3 increment in average NO2 exposure during pregnancy was associated with a 4.9% decrease in placental mtDNA content (95% CI: –9.3, –0.3%) and a 48-g decrease (95% CI: –87, –9 g) in birth weight. However, the association with birth weight was significant for INMA (–66 g; 95% CI: –111, –23 g) but not for ENVIRONAGE (–20 g; 95% CI: –101, 62 g). Placental mtDNA content was associated with significantly higher mean birth weight (pooled analysis, interquartile range increase: 140 g; 95% CI: 43, 237 g). Mediation analysis estimates, which were derived for the INMA cohort only, suggested that 10% (95% CI: 6.6, 13.0 g) of the association between prenatal NO2 and birth weight was mediated by changes in placental mtDNA content. Conclusion: Our results suggest that mtDNA content can be one of the potential mediators of the association between prenatal air pollution exposure and birth weight. Citation: Clemente DB, Casas M, Vilahur N, Begiristain H, Bustamante M, Carsin AE, Fernández MF, Fierens F, Gyselaers W, Iñiguez C, Janssen BG

  10. Predicting seed cotton moisture content from changes in drying air temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Having an accurate measurement of seed-cotton moisture content in a cotton gin would help ginners determine how much heat to use to dry the cotton. A mathematical model was used to predict seed cotton moisture content in the overhead section of a gin. The model took into account the temperature, mas...

  11. 38 CFR 3.207 - Void or annulled marriage.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Void or annulled marriage... Void or annulled marriage. Proof that a marriage was void or has been annulled should consist of: (a... marriage void, together with such other evidence as may be required for a determination. (b) Annulled....

  12. 38 CFR 3.207 - Void or annulled marriage.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Void or annulled marriage... Void or annulled marriage. Proof that a marriage was void or has been annulled should consist of: (a... marriage void, together with such other evidence as may be required for a determination. (b) Annulled....

  13. 38 CFR 3.207 - Void or annulled marriage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Void or annulled marriage... Void or annulled marriage. Proof that a marriage was void or has been annulled should consist of: (a... marriage void, together with such other evidence as may be required for a determination. (b) Annulled....

  14. 38 CFR 3.207 - Void or annulled marriage.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Void or annulled marriage... Void or annulled marriage. Proof that a marriage was void or has been annulled should consist of: (a... marriage void, together with such other evidence as may be required for a determination. (b) Annulled....

  15. 38 CFR 3.207 - Void or annulled marriage.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Void or annulled marriage... Void or annulled marriage. Proof that a marriage was void or has been annulled should consist of: (a... marriage void, together with such other evidence as may be required for a determination. (b) Annulled....

  16. Resin flow and void formation in an autoclave cure cycle

    NASA Astrophysics Data System (ADS)

    Lionetto, Francesca; Lucia, Massimo; Dell'Anna, Riccardo; Maffezzoli, Alfonso

    2016-05-01

    A finite element (FE) model able to evaluate both the evolution of resin flow, degree of reaction and void formation during autoclave cure cycles was developed. The model was implemented using a commercial epoxy matrix widely used in aeronautic field. The FE model also included a kinetic and rheological model whose input parameters were experimentally determined by Differential Scanning Calorimetry and rheological analysis. The FE model was able to predict the evolution of degree of reaction with very good agreement with the experimental data. Moreover, the predicted resin losses were lower than 3% of the overall composite resin content.

  17. Universal void density profiles from simulation and SDSS

    NASA Astrophysics Data System (ADS)

    Nadathur, S.; Hotchkiss, S.; Diego, J. M.; Iliev, I. T.; Gottlöber, S.; Watson, W. A.; Yepes, G.

    2016-10-01

    We discuss the universality and self-similarity of void density profiles, for voids in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. Voids are identified using a modified version of the ZOBOV watershed transform algorithm, with additional selection cuts. We find that voids in simulation are self-similar, meaning that their average rescaled profile does not depend on the void size, or - within the range of the simulated catalogue - on the redshift. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids.

  18. The Cosmically Depressed: Life, Sociology and Identity of Voids

    NASA Astrophysics Data System (ADS)

    van de Weygaert, R.; Platen, E.; Tigrak, E.; Hidding, J.; van der Hulst, J. M.; Aragón-Calvo, M. A.; Stanonik, K.; van Gorkom, J. H.

    2010-10-01

    In this contribution we review and discuss several aspects of Cosmic Voids, as a background for our void galaxy project (accompanying paper by Stanonik et al.). Voids are a major component of the large scale distribution of matter and galaxies in the Universe. Following a sketch of the general characteristics of void formation and evolution, we describe the influence of the environment on their development and structure and the characteristic hierarchical buildup of the cosmic void population. In order to be able to study the resulting tenuous void substructure and the galaxies populating the interior of voids, we subsequently set out to describe our parameter free tessellation-based watershed void finding technique. It allows us to trace the outline, shape and size of voids in galaxy redshift surveys. The application of this technique enables us to find galaxies in the deepest troughs of the cosmic galaxy distribution, and has formed the basis of our void galaxy program.

  19. Softening by void nucleation and growth in tension and shear

    NASA Astrophysics Data System (ADS)

    Fleck, N. A.; Hutchinson, J. W.; Tvergaard, V.

    THE EFFECT of void nucleation and growth on overall stress-strain behavior is investigated for solids undergoing plastic straining under axisymmetric and shearing conditions. Contact between the void surface and the nucleating particle is taken into account and is found to be important under shear and under axisymmetric straining when the stress triaxiality is low. The notion of the macroscopic stress drop due to nucleation of a void is defined and computed, both for isolated voids and for voids in periodic arrays. The stress drop for an isolated void in an infinite matrix can be used to predict softening due to void nucleation when the void concentration is dilute. Interaction between voids in shear during nucleation is analysed numerically and softening effects are calculated along with large strain aspects of void deformation during subsequent growth.

  20. THE METALLICITY OF VOID DWARF GALAXIES

    SciTech Connect

    Kreckel, K.; Groves, B.; Croxall, K.; Pogge, R. W.; Van de Weygaert, R.

    2015-01-01

    The current ΛCDM cosmological model predicts that galaxy evolution proceeds more slowly in lower density environments, suggesting that voids are a prime location to search for relatively pristine galaxies that are representative of the building blocks of early massive galaxies. To test the assumption that void galaxies are more pristine, we compare the evolutionary properties of a sample of dwarf galaxies selected specifically to lie in voids with a sample of similar isolated dwarf galaxies in average density environments. We measure gas-phase oxygen abundances and gas fractions for eight dwarf galaxies (M{sub r} > –16.2), carefully selected to reside within the lowest density environments of seven voids, and apply the same calibrations to existing samples of isolated dwarf galaxies. We find no significant difference between these void dwarf galaxies and the isolated dwarf galaxies, suggesting that dwarf galaxy chemical evolution proceeds independent of the large-scale environment. While this sample is too small to draw strong conclusions, it suggests that external gas accretion is playing a limited role in the chemical evolution of these systems, and that this evolution is instead dominated mainly by the internal secular processes that are linking the simultaneous growth and enrichment of these galaxies.

  1. Cosmic voids and void lensing in the Dark Energy Survey science verification data

    DOE PAGES

    Sánchez, C.; Clampitt, J.; Kovacs, A.; ...

    2016-10-26

    Galaxies and their dark matter halos populate a complicated filamentary network around large, nearly empty regions known as cosmic voids. Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of ~50 Mpc/h or more that can render many voids undetectable. In this paper we present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-zmore » redMaGiC galaxy sample of the Dark Energy Survey Science Verification (DES-SV) data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo- z scatter, the number of voids found in these projected slices of simulated spectroscopic and photometric galaxy catalogs is within 20% for all transverse void sizes, and indistinguishable for the largest voids of radius ~70 Mpc/h and larger. The positions, radii, and projected galaxy profiles of photometric voids also accurately match the spectroscopic void sample. Applying the algorithm to the DES-SV data in the redshift range 0.2 < z < 0.8 , we identify 87 voids with comoving radii spanning the range 18-120 Mpc/h, and carry out a stacked weak lensing measurement. With a significance of 4.4σ, the lensing measurement confirms the voids are truly underdense in the matter field and hence not a product of Poisson noise, tracer density effects or systematics in the data. In conclusion, it also demonstrates, for the first time in real data, the viability of void lensing studies in photometric surveys.« less

  2. Effect of Al content on impact resistance behavior of Al-Ti-B4C composite fabricated under air atmosphere.

    PubMed

    Zhao, Qian; Liang, Yunhong; Zhang, Zhihui; Li, Xiujuan; Ren, Luquan

    2016-12-01

    Reaction behavior, mechanical property and impact resistance of TiC-TiB2/Al composite reacted from Al-Ti-B4C system with various Al content via combination method of combustion synthesis and hot pressed sintering under air was investigated. Al content was the key point to the variation of mechanical property and impact resistance. Increasing Al content could increase the density, strength and toughness of the composite. Due to exorbitant ceramic content, 10wt.% and 20wt.% Al-Ti-B4C composites exhibited poor molding ability and machinability. Flexural strength, fracture toughness, compressive strength and impact toughness of 30-50wt.% Al-Ti-B4C composite were higher than those of Al matrix. The intergranular fracture dispersed and defused impact load and restricted crack extension, enhancing the impact resistance of the composite. The composite with 50wt.% Al content owned highest mechanical properties and impact resistance. The results were useful for the application of TiC-TiB2/Al composite in impact resistance field of ceramic reinforced Al matrix composite.

  3. Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors—Air Gap Effect

    PubMed Central

    Bore, Thierry; Wagner, Norman; Delepine Lesoille, Sylvie; Taillade, Frederic; Six, Gonzague; Daout, Franck; Placko, Dominique

    2016-01-01

    Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling. PMID:27096865

  4. Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors--Air Gap Effect.

    PubMed

    Bore, Thierry; Wagner, Norman; Lesoille, Sylvie Delepine; Taillade, Frederic; Six, Gonzague; Daout, Franck; Placko, Dominique

    2016-04-18

    Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling.

  5. From Voids to Yukawaballs And Back

    SciTech Connect

    Land, V.; Goedheer, W. J.

    2008-09-07

    When dust particles are introduced in a radio-frequency discharge under micro-gravity conditions, usually a dust free void is formed due to the ion drag force pushing the particles away from the center. Experiments have shown that it is possible to close the void by reducing the power supplied to the discharge. This reduces the ion density and with that the ratio between the ion drag force and the opposing electric force. We have studied the behavior of a discharge with a large amount of dust particles (radius 3.4 micron) with our hydrodynamic model, and simulated the closure of the void for conditions similar to the experiment. We also approached the formation of a Yukawa ball from the other side, starting with a discharge at low power and injecting batches of dust, while increasing the power to prevent extinction of the discharge. Eventually the same situation could be reached.

  6. Kinematics of the Local cosmic void

    NASA Astrophysics Data System (ADS)

    Nasonova, O. G.; Karachentsev, I. D.

    2011-03-01

    Available data on the distances and radial velocities of galaxies are systematized in order to study the distribution of peculiar velocities in neighborhoods of the Local cosmic void lying in the direction of the Aquila and Hercules constellations. A sample of 1056 galaxies is used, with distances measured in terms of the luminosity of the tip of the red giant branch (TRGB), the luminosity of the cepheids, the luminosity of type 1a supernovae, surface brightness fluctuations (SBF), and the Tully-Fisher relation. The amplitude of the outflow velocity of the galaxies is found to be ˜300 km/s. The average number density of galaxies inside the void is roughly a factor of five lower than the average outside it. The Local void population is characterized by lower luminosities and later morphological types, with medians of M B = - 15m.7 and T=8 (Sdm), respectively.

  7. Precision cosmology defeats void models for acceleration

    SciTech Connect

    Moss, Adam; Zibin, James P.; Scott, Douglas

    2011-05-15

    The suggestion that we occupy a privileged position near the center of a large, nonlinear, and nearly spherical void has recently attracted much attention as an alternative to dark energy. Putting aside the philosophical problems with this scenario, we perform the most complete and up-to-date comparison with cosmological data. We use supernovae and the full cosmic microwave background spectrum as the basis of our analysis. We also include constraints from radial baryonic acoustic oscillations, the local Hubble rate, age, big bang nucleosynthesis, the Compton y distortion, and for the first time include the local amplitude of matter fluctuations, {sigma}{sub 8}. These all paint a consistent picture in which voids are in severe tension with the data. In particular, void models predict a very low local Hubble rate, suffer from an ''old age problem,'' and predict much less local structure than is observed.

  8. Voids in a neutrino-dominated universe

    NASA Technical Reports Server (NTRS)

    Zeng, Ning; White, Simon D. M.

    1991-01-01

    In a neutrino-dominated universe, galaxies are expected to form only in large-scale sheets and filaments. Most of space should be filled by low-density regions devoid of galaxies. In this paper, N-body simulations are used to estimate the size distribution for these regions for quantitative comparison with the observed voids in recent red-shift surveys. The theoretical distribution depends very weakly on the mode or epoch of galaxy formation. With very conservative assumptions, at best marginal consistency is found even for cosmological parameters as extreme as Omega(v) = 1 and H(0) = 100 km/s per/Mpc. Any significant reduction in either H(0) or Omega(v) leads to predicted void sizes much larger than those observed. This difficulty arises because the observed voids are rarely completely empty.

  9. Void-Free Lid for Food Packaging

    NASA Technical Reports Server (NTRS)

    Watson, C. D.; Farris, W. P.

    1986-01-01

    Flexible cover eliminates air pockets in sealed container. Universal food-package lid formed from flexible plastic. Partially folded, lid unfolded by depressing center portion. Height of flat portion of lid above flange thereby reduced. Pressure of food against central oval depression pops it out, forming dome that provides finger grip for mixing contents with water or opening lid. Therefore food stays fresh, allows compact stacking of partially filled containers, and resists crushing. Originally developed for packaging dehydrated food for use in human consumption on Space Shuttle missions. Other uses include home canning and commercial food packaging.

  10. Firn air-content of Larsen C Ice Shelf, Antarctic Peninsula, from seismic velocities, borehole surveys and firn modelling

    NASA Astrophysics Data System (ADS)

    Kulessa, Bernd; Brisbourne, Alex; Booth, Adam; Kuipers Munneke, Peter; Bevan, Suzanne; Luckman, Adrian; Hubbard, Bryn; Gourmelen, Noel; Palmer, Steve; Holland, Paul; Ashmore, David; Shepherd, Andrew

    2016-04-01

    The rising surface temperature of Antarctic Peninsula ice shelves is strongly implicated in ice shelf disintegration, by exacerbating the compaction of firn layers. Firn compaction is expected to warm the ice column and, given sufficiently wet and compacted layers, to allow meltwater to penetrate into surface crevasses and thus enhance hydrofracture potential. Integrating seismic refraction surveys with borehole neutron and firn core density logging, we reveal vertical and horizontal changes in firn properties across Larsen C Ice Shelf. Patterns of firn air-content derived from seismic surveys are broadly similar to those estimated previously from airborne radar and satellite data. Specifically, these estimates show greater firn compaction in the north and landward inlets compared to the south, although spatial gradients in seismic-derived air-contents are less pronounced than those previously inferred. Firn thickness is less than 10 m in the extreme northwest of Larsen C, in Cabinet Inlet, yet exceeds 40 m in the southeast, suggesting that the inlet is a focus of firn compaction; indeed, buried layers of massive refrozen ice were observed in 200 MHz GPR data in Cabinet and Whirlwind Inlets during a field campaign in the 2014-15 austral summer. Depth profiles of firn density provide a reasonable fit with those derived from closely-located firn cores and neutron probe data. Our model of firn structure is driven by RACMO and includes a 'bucket'-type hydrological implementation, and simulates the depth-density profiles in the inlets well. Discrepancies between measured and modelled depth-density profiles become progressively greater towards the ice-shelf front. RACMO incorrectly simulates the particular leeward (sea-ice-influenced) microclimate of the shallow boundary layer, leading to excess melt and/or lack of snowfall. The spatial sampling density of our seismic observations will be augmented following a further field campaign in the 2016-17 austral summer

  11. [Evaluation of the content of harmful substances in the air of sewage treatment facilities of Astrakhan gas processing plant].

    PubMed

    Boĭko, V I; Dotsenko, Iu I; Boĭko, O V

    2013-01-01

    Despite the fact that the progress in regard to the degree of processing of natural gas and condensate in the Astrakhan gas processing plant is significant, necessary hygienic normalization of working environment on the part of the content of harmful substances in the air of working areas is still unable. Harmful substances were detected in the breathing zone of workers of sewage treatment plant almost constantly. In this connection there is a need in the further joint work hygienists, designers and manufacturers for the development and justification of new, more effective decisions - both on the part of as well technology as hardware design - with the purpose of improvement of working conditions.

  12. The evolution of voids in the adhesion approximation

    NASA Technical Reports Server (NTRS)

    Sahni, Varun; Sathyaprakah, B. S.; Shandarin, Sergei F.

    1994-01-01

    We apply the adhesion approximation to study the formation and evolution of voids in the universe. Our simulations-carried out using 128(exp 3) particles in a cubical box with side 128 Mpc-indicate that the void spectrum evolves with time and that the mean void size in the standard Cosmic Background Explorer Satellite (COBE)-normalized cold dark matter (CDM) model with H(sub 50) = 1 scals approximately as bar D(z) = bar D(sub zero)/(1+2)(exp 1/2), where bar D(sub zero) approximately = 10.5 Mpc. Interestingly, we find a strong correlation between the sizes of voids and the value of the primordial gravitational potential at void centers. This observation could in principle, pave the way toward reconstructing the form of the primordialpotential from a knowledge of the observed void spectrum. Studying the void spectrum at different cosmological epochs, for spectra with a built in k-space cutoff we find that the number of voids in a representative volume evolves with time. The mean number of voids first increases until a maximum value is reached (indicating that the formation of cellular structure is complete), and then begins to decrease as clumps and filaments erge leading to hierarchical clustering and the subsequent elimination of small voids. The cosmological epoch characterizing the completion of cellular structure occurs when the length scale going nonlinear approaches the mean distance between peaks of the gravitaional potential. A central result of this paper is that voids can be populated by substructure such as mini-sheets and filaments, which run through voids. The number of such mini-pancakes that pass through a given void can be measured by the genus characteristic of an individual void which is an indicator of the topology of a given void in intial (Lagrangian) space. Large voids have on an average a larger measure than smaller voids indicating more substructure within larger voids relative to smaller ones. We find that the topology of individual voids is

  13. Friction stir welding process to repair voids in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

    1999-01-01

    The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

  14. The sparkling Universe: a scenario for cosmic void motions

    NASA Astrophysics Data System (ADS)

    Ceccarelli, Laura; Ruiz, Andrés N.; Lares, Marcelo; Paz, Dante J.; Maldonado, Victoria E.; Luparello, Heliana E.; Garcia Lambas, Diego

    2016-10-01

    Cosmic voids are prominent features of the Universe, encoding relevant information of the growth and evolution of structure through their dynamics. Here, we perform a statistical study of the global motion of cosmic voids using both a numerical simulation and observational data. Their relation to large-scale mass flows and the physical effects that drive those motions. We analyse the bulk motions of voids, finding void mean bulk velocities in the range 300-400 km s-1, depending on void size and the large-scale environment. Statistically, small voids move faster, and voids in relatively higher density environments have higher bulk velocities. Also, we find large-scale overdensities (underdensities) along (opposite to) the void motion direction, suggesting that void motions respond to a pull-push mechanism. Our analysis suggests that their relative motions are generated by large-scale density fluctuations. In agreement with linear theory, voids embedded in low (high) density regions mutually recede (attract) each other, providing the general mechanism to understand the bimodal behaviour of void motions. We have also inferred void motions in the Sloan Digital Sky Survey using linear theory, finding that their estimated motions are in qualitatively agreement with the results of the simulation. Our results suggest a scenario of galaxies and galaxy systems flowing away from void centres with the additional, and more relevant, contribution of the void bulk motion to the total velocity.

  15. The view from the boundary: a new void stacking method

    NASA Astrophysics Data System (ADS)

    Cautun, Marius; Cai, Yan-Chuan; Frenk, Carlos S.

    2016-04-01

    We introduce a new method for stacking voids and deriving their profile that greatly increases the potential of voids as a tool for precision cosmology. Given that voids are distinctly non-spherical and have most of their mass at their edge, voids are better described relative to their boundary rather than relative to their centre, as in the conventional spherical stacking approach. The boundary profile is obtained by computing the distance of each volume element from the void boundary. Voids can then be stacked and their profiles computed as a function of this boundary distance. This approach enhances the weak lensing signal of voids, both shear and convergence, by a factor of 2 when compared to the spherical stacking method. It also results in steeper void density profiles that are characterized by a very slow rise inside the void and a pronounced density ridge at the void boundary. The resulting boundary density profile is self-similar when rescaled by the thickness of the density ridge, implying that the average rescaled profile is independent of void size. The boundary velocity profile is characterized by outflows in the inner regions whose amplitude scales with void size, and by a strong inflow into the filaments and walls delimiting the void. This new picture enables a straightforward discrimination between collapsing and expanding voids both for individual objects as well as for stacked samples.

  16. Finding high-redshift voids using Lyman α forest tomography

    NASA Astrophysics Data System (ADS)

    Stark, Casey W.; Font-Ribera, Andreu; White, Martin; Lee, Khee-Gan

    2015-11-01

    We present a new method of finding cosmic voids using tomographic maps of Lyα forest flux. We identify cosmological voids with radii of 2-12 h-1 Mpc in a large N-body simulation at z = 2.5, and characterize the signal of the high-redshift voids in density and Lyα forest flux. The void properties are similar to what has been found at lower redshifts, but they are smaller and have steeper radial density profiles. Similarly to what has been found for low-redshift voids, the radial velocity profiles have little scatter and agree very well with the linear theory prediction. We run the same void finder on an ideal Lyα flux field and tomographic reconstructions at various spatial samplings. We compare the tomographic map void catalogues to the density void catalogue and find good agreement even with modest-sized voids (r > 6 h-1 Mpc). Using our simple void-finding method, the configuration of the ongoing COSMOS Lyman Alpha Mapping And Tomography Observations (CLAMATO) survey covering 1 deg2 would provide a sample of about 100 high-redshift voids. We also provide void-finding forecasts for larger area surveys, and discuss how these void samples can be used to test modified gravity models, study high-redshift void galaxies, and to make an Alcock-Paczynski measurement. To aid future work in this area, we provide public access to our simulation products, catalogues, and sample tomographic flux maps.

  17. Void fraction instrument acceptance test procedure

    SciTech Connect

    Pearce, K.L.

    1994-09-15

    This acceptance test procedure (ATP) was written to test the void fraction instrument (VFI) and verify that the unit is ready for field service. The procedure verifies that the mechanical and electrical features (not specifically addressed in the software ATP) and software alarms are operating as designed.

  18. "Dark energy" in the Local Void

    NASA Astrophysics Data System (ADS)

    Villata, M.

    2012-05-01

    The unexpected discovery of the accelerated cosmic expansion in 1998 has filled the Universe with the embarrassing presence of an unidentified "dark energy", or cosmological constant, devoid of any physical meaning. While this standard cosmology seems to work well at the global level, improved knowledge of the kinematics and other properties of our extragalactic neighborhood indicates the need for a better theory. We investigate whether the recently suggested repulsive-gravity scenario can account for some of the features that are unexplained by the standard model. Through simple dynamical considerations, we find that the Local Void could host an amount of antimatter (˜5×1015 M ⊙) roughly equivalent to the mass of a typical supercluster, thus restoring the matter-antimatter symmetry. The antigravity field produced by this "dark repulsor" can explain the anomalous motion of the Local Sheet away from the Local Void, as well as several other properties of nearby galaxies that seem to require void evacuation and structure formation much faster than expected from the standard model. At the global cosmological level, gravitational repulsion from antimatter hidden in voids can provide more than enough potential energy to drive both the cosmic expansion and its acceleration, with no need for an initial "explosion" and dark energy. Moreover, the discrete distribution of these dark repulsors, in contrast to the uniformly permeating dark energy, can also explain dark flows and other recently observed excessive inhomogeneities and anisotropies of the Universe.

  19. Finding Mount Everest and handling voids.

    PubMed

    Storch, Tobias

    2011-01-01

    Evolutionary algorithms (EAs) are randomized search heuristics that solve problems successfully in many cases. Their behavior is often described in terms of strategies to find a high location on Earth's surface. Unfortunately, many digital elevation models describing it contain void elements. These are elements not assigned an elevation. Therefore, we design and analyze simple EAs with different strategies to handle such partially defined functions. They are experimentally investigated on a dataset describing the elevation of Earth's surface. The largest value found by an EA within a certain runtime is measured, and the median over a few runs is computed and compared for the different EAs. For the dataset, the distribution of void elements seems to be neither random nor adversarial. They are so-called semirandomly distributed. To deepen our understanding of the behavior of the different EAs, they are theoretically considered on well-known pseudo-Boolean functions transferred to partially defined ones. These modifications are also performed in a semirandom way. The typical runtime until an optimum is found by an EA is analyzed, namely bounded from above and below, and compared for the different EAs. We figure out that for the random model it is a good strategy to assume that a void element has a worse function value than all previous elements. Whereas for the adversary model it is a good strategy to assume that a void element has the best function value of all previous elements.

  20. Cosmic Voids As Standard Rulers For Cosmology

    NASA Astrophysics Data System (ADS)

    Lavaux, Guilhem; Wandelt, B. D.

    2012-01-01

    We show a purely geometrical method for probing the expansion history of the Universe from the observation of the shape of stacked voids in spectroscopic redshift surveys. This method is an Alcock-Pasczynski test based on the average sphericity of voids posited on the local isotropy of the Universe, which acts as rulers of unknown size. We describe the algorithm that we use to detect and stack voids in redshift shells on the light cone. We establish, and test on N-body simulation, a robust statistical model for estimating the average stretching of voids in redshift space. Finally, we discuss the constraining power on dark energy parameters in terms of the figure of merit of the Dark Energy Task Force. We estimate the figure of merit for SDSS, BOSS and EUCLID class surveys. For Euclid, the figure of merit is an order of magnitude higher than Baryonic Acoustic Oscillation based methods. We acknowledge financial support from NSF Grant AST 07-08849, AST 09-08693 and from BDW's Chaire d'Excellence granted by the Agence Nationale de Recherche. GL acknowledges support from CITA National Fellowship and financial support from the Government of Canada Post-Doctoral Research Fellowship.

  1. Atomistic modeling of shock-induced void collapse in copper

    SciTech Connect

    Davila, L P; Erhart, P; Bringa, E M; Meyers, M A; Lubarda, V A; Schneider, M S; Becker, R; Kumar, M

    2005-03-09

    Nonequilibrium molecular dynamics (MD) simulations show that shock-induced void collapse in copper occurs by emission of shear loops. These loops carry away the vacancies which comprise the void. The growth of the loops continues even after they collide and form sessile junctions, creating a hardened region around the collapsing void. The scenario seen in our simulations differs from current models that assume that prismatic loop emission is responsible for void collapse. We propose a new dislocation-based model that gives excellent agreement with the stress threshold found in the MD simulations for void collapse as a function of void radius.

  2. Dynamics of air gap formation around roots with changing soil water content.

    NASA Astrophysics Data System (ADS)

    Vetterlein, D.; Carminati, A.; Weller, U.; Oswald, S.; Vogel, H.-J.

    2009-04-01

    Most models regarding uptake of water and nutrients from soil assume intimate contact between roots and soil. However, it is known for a long time that roots may shrink under drought conditions. Due to the opaque nature of soil this process could not be observed in situ until recently. Combining tomography of the entire sample (field of view of 16 x 16 cm, pixel side 0.32 mm) with local tomography of the soil region around roots (field of view of 5 x 5 cm, pixel side 0.09 mm), the high spatial resolution required to image root shrinkage and formation of air-filled gaps around roots could be achieved. Applying this technique and combining it with microtensiometer measurements, measurements of plant gas exchange and microscopic assessment of root anatomy, a more detailed study was conducted to elucidate at which soil matric potential roots start to shrink in a sandy soil and which are the consequences for plant water relations. For Lupinus albus grown in a sandy soil tomography of the entire root system and of the interface between taproot and soil was conducted from day 11 to day 31 covering two drying cycles. Soil matric potential decreased from -36 hPa at day 11 after planting to -72, -251, -429 hPa, on day 17, 19, 20 after planting. On day 20 an air gap started to occur around the tap root and extended further on day 21 with matric potential below -429 hPa (equivalent to 5 v/v % soil moisture). From day 11 to day 21 stomatal conductivity decreased from 467 to 84 mmol m-2 s-1, likewise transpiration rate decreased and plants showed strong wilting symptoms on day 21. Plants were watered by capillary rise on day 21 and recovered completely within a day with stomatal conductivity increasing to 647 mmol m-2 s-1. During a second drying cycle, which was shorter as plants continuously increased in size, air gap formed again at the same matric potential. Plant stomatal conductance and transpiration decreased in a similar fashion with decreasing matric potential and

  3. Relationship between voids and interlaminar shear strength of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Frimpong, Stephen

    1991-01-01

    The effect of voids on the interlaminar shear strength of a polyimide matrix composite system is described. The AS4 graphite/PMR-15 composite was chosen for study because this system can be readily processed by using the standard specified cure cycle to produce void-free composites and because preliminary work in this study had shown that the processing parameters of this resin matrix system can be altered to produce cured composites of varying void contents. Thirty-eight 12-ply unidirectional composite panels were fabricated for this study. A significant range of void contents (0 to 10 percent) was produced. The panels were mapped, ultrasonically inspected, and sectioned into interlaminar shear, flexure, and fiber content specimens. The density of each specimen was measured and interlaminar shear and flexure strength measurements were then made. The fiber content was measured last. The results of these tests were evaluated by using ultrasonic results, photomicrographs, statistical methods, theoretical relationships derived by other investigators, and comparison of the test data with the Integrated Composite Analyzer (ICAN) computer program developed at the Lewis Research Center for predicting composite ply properties. The testing is described in as much detail as possible in order to help others make realistic comparisons.

  4. Influence of local air flow regimes on the ozone content of two Pyrenean valleys

    NASA Astrophysics Data System (ADS)

    Ezcurra, A.; Benech, B.; Echelecou, A.; Santamaría, J. M.; Herrero, I.; Zulueta, E.

    2013-08-01

    The Pyrenees Mountains, the natural border between France and Spain, have experienced a large increase in road traffic in the last decade. Due to this fact, a research program named PAP (Pollution Atmospheric in the Pyrenees) was established in 2004 by several laboratories from Spain and France to address the influence of meteorological regimes on the pollution levels of two adjacent valleys, Aspe valley (France) and Canfranc valley (Spain), situated in the center of the Pyrenean range. Pollution measurements show that mean ozone concentrations increase with height. In Sarrance, the site placed at the bottom of the valleys at 335 m above sea level (ASL), the mean ozone value was 23 ppb, whereas at the Pic Midi observatory (2877 m ASL), the top of the PAP network, the value found for mean ozone values was 52 ppb. A linear trend fits this altitudinal variation with a vertical gradient of 17 ppb km-1. The data demonstrate that the observatories located over 1400 m ASL do not show the classical mean daily ozone cycle, and that mean ozone concentrations throughout the day are nearly constant. By contrast, below 1400 m ASL, the classical mean daily ozone cycle is clear, reaching a maximum around noon. These findings indicate that the photochemical reactions are almost inactive at the elevated observatories and, as a result, it can be concluded that ozone levels at those locations are mostly caused by advection of aged air masses. Consequently, we could find that the gradient inside the valleys follows a linear trend of 29 ppb km-1. Finally, it has been observed that in north Foehn situations, intrusions of polluted air coming from the Free Troposphere (FT) can be detected in the upper part of the Spanish valley of Canfranc, where the mean daily ozone cycle changes significantly and becomes similar to the ones measured at the stations situated above 1400 m ASL. However, the results also pointed out that, except for the Foehn situations, the different local air flow

  5. Two-Phase Void Drift Phenomena in a 2 x 3 Rod Bundle: Flow Redistribution Data and Their Analysis

    SciTech Connect

    Sadatomi, Michio; Kawahara, Akimaro; Kuno, Tsukasa; Kano, Keiko

    2005-10-15

    To improve a void drift model used in a subchannel analysis, new experimental data are obtained for air-water two-phase flows in a vertical 2 x 3 rod channel consisting of six subchannels simulating a square array boiling water reactor fuel rod bundle. The data include the axial redistributions of flow rates of both phases and void fraction in the respective subchannels. By fitting the above data with the Lahey and Moody void settling model, we have determined a void diffusion coefficient in their model. It is found that the void diffusion coefficient for slug, churn, and annular flows could be well correlated in terms of a turbulent Peclet number developed in our previous study. Furthermore, a subchannel analysis code based on a two-fluid model proposed in our previous study is examined against the present data. In the code, the void settling model is incorporated with usual conservation equations of mass and momentum. From the examination, it is found that the subchannel analysis code can predict well the data on subchannel flow and void fraction for the 2 x 3 rod channel if appropriate correlations are adopted to evaluate wall and interfacial friction forces needed in the two-fluid model.

  6. Ductile fracture by cavity nucleation between larger voids

    NASA Astrophysics Data System (ADS)

    Tvergaard, Viggo

    1982-08-01

    A MECHANISM of ductile fracture involving the interaction of relatively large voids with small-scale voids is studied by a computational model. The larger voids are described as circular cylindrical holes arranged in a doubly periodic array in the initial state. In the matrix material between these voids the nucleation and growth of much smaller voids is accounted for by using approximate constitutive equations for a ductile, porous medium. The computations show bands of highly localized straining and void growth, initiating at the surfaces of larger voids and growing into the matrix material, until the bands connect two neighbouring voids. The materials are analysed both under plane strain conditions and under conditions approximating those in a round tensile bar. The failure strains obtained under different principal stress ratios show rather good agreement when plotted against a measure of the stress-triaxiality.

  7. Tank SY-101 void fraction instrument functional design criteria

    SciTech Connect

    McWethy, L.M.

    1994-10-18

    This document presents the functional design criteria for design, analysis, fabrication, testing, and installation of a void fraction instrument for Tank SY-101. This instrument will measure the void fraction in the waste in Tank SY-101 at various elevations.

  8. Measurement and Analysis of Void Fraction in a Multiple-Channel Simplifying Triangle Tight Lattice Rod Bundle

    SciTech Connect

    Michio Sadatomi; Akimaro Kawahara; Hiroyuki Kudo; Hiroshi Shirai

    2006-07-01

    In order to know the effects of reduced surface tension on void fraction, adiabatic experiments were conducted for both air-water and air-water with surfactant systems at room temperature and pressure. Void fraction data were obtained for bubbly, slug, churn and annular flows in a vertical channel with two subchannels simplifying a triangle tight lattice rod bundle. The void fraction was found to be lower in air-water system than air-water with surfactant one. In addition, the void fractions for both systems were found to be lower than those calculated by various correlations in literatures for circular pipe flow. In order to study the cause of the above data trend, for annular flows as a first step, the void fraction has been calculated by a subchannel analysis using wall and interfacial friction correlations in literatures as constitutive equations, and by assuming the liquid film to be uniform over the wall perimeter. The best agreement between the calculation and the experiment has been obtained when NASCA correlation for wall friction force and modified RELAP5/MOD2 correlation incorporating reduced surface tension effects for interfacial friction force were used. (authors)

  9. 21 CFR 1305.28 - Canceling and voiding electronic orders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Canceling and voiding electronic orders. 1305.28... I AND II CONTROLLED SUBSTANCES Electronic Orders § 1305.28 Canceling and voiding electronic orders. (a) A supplier may void all or part of an electronic order by notifying the purchaser of the...

  10. The VIMOS Public Extragalactic Redshift Survey. Searching for cosmic voids

    NASA Astrophysics Data System (ADS)

    Micheletti, D.; Iovino, A.; Hawken, A. J.; Granett, B. R.; Bolzonella, M.; Cappi, A.; Guzzo, L.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bottini, D.; Branchini, E.; Coupon, J.; Cucciati, O.; Davidzon, I.; De Lucia, G.; de la Torre, S.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Polletta, M.; Pollo, A.; Schimd, C.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moutard, T.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Zamorani, G.

    2014-10-01

    Context. The characterisation of cosmic voids gives unique information about the large-scale distribution of galaxies, their evolution, and thecosmological model. Aims: We identify and characterise cosmic voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS) at redshift 0.55 void search method is developed based upon the identification of empty spheres that fit between galaxies. The method can be used to characterise the cosmic voids despite the presence of complex survey boundaries and internal gaps. We investigate the impact of systematic observational effects and validate the method against mock catalogues. We measure the void size distribution and the void-galaxy correlation function. Results: We construct a catalogue of voids in VIPERS. The distribution of voids is found to agree well with the distribution of voids found in mock catalogues. The void-galaxy correlation function shows indications of outflow velocity from the voids. The voids catalogue (Table 3) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/570/A106

  11. Extended void merging tree algorithm for self-similar models

    NASA Astrophysics Data System (ADS)

    Russell, Esra

    2014-02-01

    In hierarchical evolution, voids exhibit two different behaviours related with their surroundings and environments, they can merge or collapse. These two different types of void processes can be described by the two-barrier excursion set formalism based on Brownian random walks. In this study, the analytical approximate description of the growing void merging algorithm is extended by taking into account the contributions of voids that are embedded into overdense region(s) which are destined to vanish due to gravitational collapse. Following this, to construct a realistic void merging model that consists of both collapse and merging processes, the two-barrier excursion set formalism of the void population is used. Assuming spherical voids in the Einstein-de Sitter Universe, the void merging algorithm which allows us to consider the two main processes of void hierarchy in one formalism is constructed. In addition to this, the merger rates, void survival probabilities, void size distributions in terms of the collapse barrier and finally, the void merging tree algorithm in the self-similar models are defined and derived.

  12. Modeling the soil water retention properties of same-textured soils with different initial void ratios

    NASA Astrophysics Data System (ADS)

    Tan, Fang; Zhou, Wan-Huan; Yuen, Ka-Veng

    2016-11-01

    This study presents a method of predicting the soil water retention curve (SWRC) of a soil using a set of measured SWRC data from a soil with the same texture but different initial void ratio. The relationships of the volumetric water contents and the matric suctions between two samples with different initial void ratios are established. An adjustment parameter (β) is introduced to express the relationships between the matric suctions of two soil samples. The parameter β is a function of the initial void ratio, matric suction or volumetric water content. The function can take different forms, resulting in different predictive models. The optimal predictive models of β are determined for coarse-grained and fine-grained soils using the Bayesian method. The optimal models of β are validated by comparing the estimated matric suction and measured data. The comparisons show that the proposed method produces more accurate SWRCs than do other models for both coarse-grained and fine-grained soils. Furthermore, the influence of the model parameters of β on the predicted matric suction and SWRC is evaluated using Latin Hypercube sampling. An uncertainty analysis shows that the reliability of the predicted SWRC decreases with decreasing water content in fine-grained soils, and the initial void ratio has no apparent influence on the reliability of the predicted SWRCs in coarse-grained and fine-grained soils.

  13. In situ determination of rheological properties and void fraction: Hanford Waste Tank 241-SY-103

    SciTech Connect

    Shepard, C.L.; Stewart, C.W.; Alzheimer, J.M.; Terrones, G.; Chen, G.; Wilkins, N.E.

    1995-11-01

    This report presents the results of the operation of the void fraction instrument (VFI) and ball rheometer in Hanford Tank 241-SY-103. The two instruments were deployed through risers 17C and 22A in July and August 1995 to gather data on the gas content and rheology of the waste. The results indicate that the nonconvective sludge layer contains up to 12% void and an apparent viscosity of 104 to 105 cP with a yield strength less than 210 Pa. The convective layer measured zero void and had no measurable yield strength. Its average viscosity was about 45 cP, and the density was less than 1.5 g/cc. The average void fraction was 0.047 {plus_minus} 0.015 at riser 17C and 0.091 {plus_minus} 0.015 at riser 22A. The stored gas volume based on these void fraction measurements is 213 {plus_minus} 42 M{sup 3} at 1 atmosphere.

  14. Biodrying of sewage sludge: kinetics of volatile solids degradation under different initial moisture contents and air-flow rates.

    PubMed

    Villegas, Manuel; Huiliñir, Cesar

    2014-12-01

    This study focuses on the kinetics of the biodegradation of volatile solids (VS) of sewage sludge for biodrying under different initial moisture contents (Mc) and air-flow rates (AFR). For the study, a 3(2) factorial design, whose factors were AFR (1, 2 or 3L/minkgTS) and initial Mc (59%, 68% and 78% w.b.), was used. Using seven kinetic models and a nonlinear regression method, kinetic parameters were estimated and the models were analyzed with two statistical indicators. Initial Mc of around 68% increases the temperature matrix and VS consumption, with higher moisture removal at lower initial Mc values. Lower AFRs gave higher matrix temperatures and VS consumption, while higher AFRs increased water removal. The kinetic models proposed successfully simulate VS biodegradation, with root mean square error (RMSE) between 0.007929 and 0.02744, and they can be used as a tool for satisfactory prediction of VS in biodrying.

  15. Process Yields Strong, Void-Free Laminates

    NASA Technical Reports Server (NTRS)

    Bryant, L. E.; Covington, E. W., III; Dale, W. J.; Hall, E. T., Jr; Justice, J. E.; Taylor, E. C.; Wilson, M. L.

    1983-01-01

    Need for lightweight materials as structural components for future space transportation systems stimulated development of systematic method for manufacturing a polyimide/graphite composite. Laminates manufactured by process are void-free, exhibit excellent thermo-oxidative stability up to 315 degrees C (600 degrees F) and are 40 percent lighter than aluminum. Process is precise, repeatable, and ideally suited for researchers and small-lot producers of composite materials.

  16. Effects of liquid VOC concentration and salt content on partitioning equilibrium of hydrophilic VOC at air-sweat interface

    NASA Astrophysics Data System (ADS)

    Cheng, Wen-Hsi; Chu, Fu-Sui; Su, Tzy-I.

    Volatile organic compounds (VOCs) must initially be absorbed by sweat on the surface of skin for human VOC dermal exposure. The partitioning equilibrium at the air-sweat interface is given by p=Cg*/C, where pc is the partitioning coefficient, and Cg* is the gaseous concentration in equilibrium with the aqueous VOC concentration ( CL) at a constant water temperature ( Tw). A series of thermodynamic functions of Cg*(C,T) are presented, as well as the values of pc, and the heat of gaseous-liquid phase transfer (Δ Htr) for tested VOCs, including iso-propanol (IPA, CL=12-120 mg L -1) and methyl ethyl ketone (MEK, CL=10-80 mg L -1) to determine the effects of liquid VOC concentration and salt contents of sweat on pc of hydrophilic VOCs. Experimental data reveal that the pc values of IPA and MEK drop as the liquid VOC concentrations increasing from 10 to 120 mg L -1. However, sodium salt content in human sweat (sodium chloride and sodium lactate) induces the effect of salt, indicating the increase in pc. Notably, neither urea nor ammonia in human sweat increase pc. Artificial sweat, consisting of sodium chloride 0.47%, urea 0.05%, ammonia 0.004% and sodium lactate 0.6%, was used to evaluate the increase in the pc values of IPA and MEK. The liquid VOC concentration effect simultaneously develops together with the salt effect on the partition at the interface of air-sweat for hydrophilic VOC solutions. The pc values of IPA for artificial sweat decrease as much as 32.5% as CL increases from 12 to 120 mg L -1 at 300 K, and those of MEK drop by as much as 70.9% as CL increases from 10 to 80 mg L -1 at 300 K. This investigation provides a basis for elucidating the assessment of human dermal exposure to hydrophilic VOCs.

  17. Climatic and insolation control on the high-resolution total air content in the NGRIP ice core

    NASA Astrophysics Data System (ADS)

    Eicher, Olivier; Baumgartner, Matthias; Schilt, Adrian; Schmitt, Jochen; Schwander, Jakob; Stocker, Thomas F.; Fischer, Hubertus

    2016-10-01

    Because the total air content (TAC) of polar ice is directly affected by the atmospheric pressure and temperature, its record in polar ice cores was initially considered as a proxy for past ice sheet elevation changes. However, the Antarctic ice core TAC record is known to also contain an insolation signature, although the underlying physical mechanisms are still a matter of debate. Here we present a high-resolution TAC record over the whole North Greenland Ice Core Project ice core, covering the last 120 000 years, which independently supports an insolation signature in Greenland. Wavelet analysis reveals a clear precession and obliquity signal similar to previous findings on Antarctic TAC, with a different insolation history. In our high-resolution record we also find a decrease of 4-6 % (4-5 mL kg-1) in TAC as a response to Dansgaard-Oeschger events (DO events). TAC starts to decrease in parallel to increasing Greenland surface temperature and slightly before CH4 reacts to the warming but also shows a two-step decline that lasts for several centuries into the warm interstadial. The TAC response is larger than expected considering only changes in air density by local temperature and atmospheric pressure as a driver, pointing to a transient firnification response caused by the accumulation-induced increase in the load on the firn at bubble close-off, while temperature changes deeper in the firn are still small.

  18. Void reduction in autoclave processing of thermoset composites. I - High pressure effects on void reduction. II - Void reduction in a microwave curing process

    NASA Astrophysics Data System (ADS)

    Boey, F. Y. C.; Lye, S. W.

    1992-07-01

    Two novel methods for reducing void levels in thermoset composites are reported. The first procedure, which eliminates vacuum application, uses high pressure of up to 7000 kPa, by means of an isostatic press, effectively reducing the void levels to below 3 percent. The second process uses microwave curing by means of a modified approach involving vacuum bagging and applied autoclave pressure. This process achieves a void level of 4 percent.

  19. Gas-liquid Phase Distribution and Void Fraction Measurements Using the MRI

    NASA Technical Reports Server (NTRS)

    Daidzic, N. E.; Schmidt, E.; Hasan, M. M.; Altobelli, S.

    2004-01-01

    We used a permanent-magnet MRI system to estimate the integral and spatially- and/or temporally-resolved void-fraction distributions and flow patterns in gas-liquid two-phase flows. Air was introduced at the bottom of the stagnant liquid column using an accurate and programmable syringe pump. Air flow rates were varied between 1 and 200 ml/min. The cylindrical non-conducting test tube in which two-phase flow was measured was placed in a 2.67 kGauss MRI with MRT spectrometer/imager. Roughly linear relationship has been obtained for the integral void-fraction, obtained by volume-averaging of the spatially-resolved signals, and the air flow rate in upward direction. The time-averaged spatially-resolved void fraction has also been obtained for the quasi-steady flow of air in a stagnant liquid column. No great accuracy is claimed as this was an exploratory proof-of-concept type of experiment. Preliminary results show that MRI a non-invasive and non-intrusive experimental technique can indeed provide a wealth of different qualitative and quantitative data and is especially well suited for averaged transport processes in adiabatic and diabatic multi-phase and/or multi-component flows.

  20. A Cosmic Void Catalog of SDSS DR12 BOSS Galaxies

    NASA Astrophysics Data System (ADS)

    Mao, Qingqing; Berlind, Andreas A.; Scherrer, Robert J.; Neyrinck, Mark C.; Scoccimarro, Román; Tinker, Jeremy L.; McBride, Cameron K.; Schneider, Donald P.; Pan, Kaike; Bizyaev, Dmitry; Malanushenko, Elena; Malanushenko, Viktor

    2017-02-01

    We present a cosmic void catalog using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We take into account the survey boundaries, masks, and angular and radial selection functions, and apply the ZOBOV void finding algorithm to the Galaxy catalog. We identify a total of 10,643 voids. After making quality cuts to ensure that the voids represent real underdense regions, we obtain 1,228 voids with effective radii spanning the range 20–100 {h}-1 {Mpc} and with central densities that are, on average, 30% of the mean sample density. We release versions of the catalogs both with and without quality cuts. We discuss the basic statistics of voids, such as their size and redshift distributions, and measure the radial density profile of the voids via a stacking technique. In addition, we construct mock void catalogs from 1000 mock galaxy catalogs, and find that the properties of BOSS voids are in good agreement with those in the mock catalogs. We compare the stellar mass distribution of galaxies living inside and outside of the voids, and find no large difference. These BOSS and mock void catalogs are useful for a number of cosmological and galaxy environment studies.

  1. Electromigration-driven shape evolution of two-dimensional voids

    NASA Astrophysics Data System (ADS)

    Schimschak, M.; Krug, J.

    2000-01-01

    We present a detailed numerical study of the electromigration-induced shape evolution of quasi-two-dimensional (cylindrical) voids in metallic thin films. The problem is treated within a continuum formulation which takes into account mass transport along surfaces, current crowding, and crystal anisotropy in the surface mobility. Finite strips with periodic boundary conditions in the current direction are treated as well as voids in infinite or semi-infinite films. For the strip geometry, it is shown that the linear instability of the strip edge can induce the release of voids into the interior of the film, while edge voids develop into fatal slits only in the presence of moderate (not too strong) crystalline anisotropy. Distorted voids in an infinite film typically disintegrate, but the breakup scenario is qualitatively different in isotropic and anisotropic media. A rigid boundary attracts voids and may also induce void breakup.

  2. The void galaxy survey: photometry, structure and identity of void galaxies

    NASA Astrophysics Data System (ADS)

    Beygu, B.; Peletier, R. F.; Hulst, J. M. van der; Jarrett, T. H.; Kreckel, K.; Weygaert, R. van de; van Gorkom, J. H.; Aragon-Calvo, M. A.

    2017-01-01

    We analyse photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6 μm and 4.5 μm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the Sloan Digital Sky Survey Data Release 7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from MB = -15.5 to -20, while at the 3.6 μm band their magnitudes range from M3.6 = -18 to -24. Their B-[3.6] colour and structural parameters indicate these are star-forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 1010 M⊙. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.

  3. Surgical Management of Male Voiding Dysfunction.

    PubMed

    Mandeville, Jessica; Mourtzinos, Arthur

    2016-06-01

    Benign prostatic hypertrophy (BPH) is a common cause of voiding dysfunction. BPH may lead to bladder outlet obstruction and resultant troublesome lower urinary tract symptoms. Initial management of BPH and bladder outlet obstruction is typically conservative. However, when symptoms are severe or refractory to medical therapy or when urinary retention, bladder stone formation, recurrent urinary tract infections, or upper urinary tract deterioration occur, surgical intervention is often necessary. Numerous options are available for surgical management of BPH ranging from simple office-based procedures to transurethral operative procedures and even open and robotic surgeries. This article reviews the current, most commonly used techniques available for surgical management of BPH.

  4. Effect of initial moisture content on the in-vessel composting under air pressure of organic fraction of municipal solid waste in Morocco.

    PubMed

    Makan, Abdelhadi; Assobhei, Omar; Mountadar, Mohammed

    2013-01-03

    This study aimed to evaluate the effect of initial moisture content on the in-vessel composting under air pressure of organic fraction of municipal solid waste in Morocco in terms of internal temperature, produced gases quantity, organic matter conversion rate, and the quality of the final composts.For this purpose, in-vessel bioreactor was designed and used to evaluate both appropriate initial air pressure and appropriate initial moisture content for the composting process. Moreover, 5 experiments were carried out within initial moisture content of 55%, 65%, 70%, 75% and 85%. The initial air pressure and the initial moisture content of the mixture showed a significant effect on the aerobic composting. The experimental results demonstrated that for composting organic waste, relatively high moisture contents are better at achieving higher temperatures and retaining them for longer times.This study suggested that an initial moisture content of around 75%, under 0.6 bar, can be considered as being suitable for efficient composting of organic fraction of municipal solid waste. These last conditions, allowed maximum value of temperature and final composting product with good physicochemical properties as well as higher organic matter degradation and higher gas production. Moreover, final compost obtained showed good maturity levels and can be used for agricultural applications.

  5. Unambiguous voids in Allende chondrules and refractory inclusions

    SciTech Connect

    Murray, J.; Boesenberg, J.S.; Ebel, D.S.

    2003-03-26

    Void space can be caused by thin section preparation. 3-dimensional tomographic analysis, prior to sectioning, shows that several very different types of voids are abundant in Allende meteorite inclusions. Formation models are proposed for each type. Void spaces in the components of chondritic meteorites have received little attention, perhaps due to ambiguities attendant upon their very existence, and also their origin. Computer-aided microtomography allows the 3-dimensional imaging and analysis of void spaces within solid objects. Several striking examples of void spaces, apparently enclosed by solid material, resulted from our observations of large chondrules and CAIs from the Allende (CV3) meteorite. These voids are 'unambiguous' because their existence cannot be ascribed to plucking during sample preparation, as would be the case in traditional 2-dimensional thin section petrography. Although we focus on large objects in Allende, preliminary observations indicate that void spaces are prevalent in chondrules and refractory inclusions in many meteorites. Voids remain ambiguous, however, because their structure and appearance vary between chondrules and CAIs, suggesting there may be different causes of void formation in particular objects. Some voids appear to have formed as a result of dilation during cooling. Others are evidence of hydrothermal leaching on the parent body followed by partial chemical replacement. Alternatively, vapor-mediated leaching and replacement may have occurred in the nebula. Yet another possibility is internal brecciation caused by impact, while the object was still free floating in the nebula, and perhaps still partially molten.

  6. Voiding Dysfunction after Total Mesorectal Excision in Rectal Cancer

    PubMed Central

    Kim, Jae Heon; Noh, Tae Il; Oh, Mi Mi; Park, Jae Young; Lee, Jeong Gu; Um, Jun Won; Min, Byung Wook

    2011-01-01

    Purpose The aim of this study was to assess the voiding dysfunction after rectal cancer surgery with total mesorectal excision (TME). Methods This was part of a prospective study done in the rectal cancer patients who underwent surgery with TME between November 2006 and June 2008. Consecutive uroflowmetry, post-voided residual volume, and a voiding questionnaire were performed at preoperatively and postoperatively. Results A total of 50 patients were recruited in this study, including 28 male and 22 female. In the comparison of the preoperative data with the postoperative 3-month data, a significant decrease in mean maximal flow rate, voided volume, and post-voided residual volume were found. In the comparison with the postoperative 6-month data, however only the maximal flow rate was decreased with statistical significance (P=0.02). In the comparison between surgical methods, abdominoperineal resection patients showed delayed recovery of maximal flow rate, voided volume, and post-voided residual volume. There was no significant difference in uroflowmetry parameters with advances in rectal cancer stage. Conclusions Voiding dysfunction is common after rectal cancer surgery but can be recovered in 6 months after surgery or earlier. Abdominoperineal resection was shown to be an unfavorable factor for postoperative voiding. Larger prospective study is needed to determine the long-term effect of rectal cancer surgery in relation to male and female baseline voiding condition. PMID:22087426

  7. A New Statistical Perspective on the Cosmic Void Distribution

    NASA Astrophysics Data System (ADS)

    Pycke, J.-R.; Russell, E.

    2016-04-01

    In this study, we obtain the size distribution of voids as a three-parameter redshift-independent log-normal void probability function (VPF) directly from the Cosmic Void Catalog (CVC). Although many statistical models of void distributions are based on the counts in randomly placed cells, the log-normal VPF that we obtain here is independent of the shape of the voids due to the parameter-free void finder of the CVC. We use three void populations drawn from the CVC generated by the Halo Occupation Distribution (HOD) Mocks, which are tuned to three mock SDSS samples to investigate the void distribution statistically and to investigate the effects of the environments on the size distribution. As a result, it is shown that void size distributions obtained from the HOD Mock samples are satisfied by the three-parameter log-normal distribution. In addition, we find that there may be a relation between the hierarchical formation, skewness, and kurtosis of the log-normal distribution for each catalog. We also show that the shape of the three-parameter distribution from the samples is strikingly similar to the galaxy log-normal mass distribution obtained from numerical studies. This similarity between void size and galaxy mass distributions may possibly indicate evidence of nonlinear mechanisms affecting both voids and galaxies, such as large-scale accretion and tidal effects. Considering the fact that in this study, all voids are generated by galaxy mocks and show hierarchical structures in different levels, it may be possible that the same nonlinear mechanisms of mass distribution affect the void size distribution.

  8. A SIMPLE GRAVITATIONAL LENS MODEL FOR COSMIC VOIDS

    SciTech Connect

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu

    2015-05-10

    We present a simple gravitational lens model to illustrate the ease of using the embedded lensing theory when studying cosmic voids. It confirms the previously used repulsive lensing models for deep voids. We start by estimating magnitude fluctuations and weak-lensing shears of background sources lensed by large voids. We find that sources behind large (∼90 Mpc) and deep voids (density contrast about −0.9) can be magnified or demagnified with magnitude fluctuations of up to ∼0.05 mag and that the weak-lensing shear can be up to the ∼10{sup −2} level in the outer regions of large voids. Smaller or shallower voids produce proportionally smaller effects. We investigate the “wiggling” of the primary cosmic microwave background (CMB) temperature anisotropies caused by intervening cosmic voids. The void-wiggling of primary CMB temperature gradients is of the opposite sign to that caused by galaxy clusters. Only extremely large and deep voids can produce wiggling amplitudes similar to galaxy clusters, ∼15 μK by a large void of radius ∼4° and central density contrast −0.9 at redshift 0.5 assuming a CMB background gradient of ∼10 μK arcmin{sup −1}. The dipole signal is spread over the entire void area, and not concentrated at the lens center as it is for clusters. Finally, we use our model to simulate CMB sky maps lensed by large cosmic voids. Our embedded theory can easily be applied to more complicated void models and used to study gravitational lensing of the CMB, to probe dark matter profiles, to reduce the lensing-induced systematics in supernova Hubble diagrams, and to study the integrated Sachs–Wolfe effect.

  9. Detection of underground voids in Ohio by use of geophysical methods

    USGS Publications Warehouse

    Munk, Jens; Sheets, R.A.

    1997-01-01

    Geophysical methods are generally classified as electrical, potential field, and seismic methods. Each method type relies on contrasts of physical properties in the subsurface. Forward models based on the physical properties of air- and water-filled voids within common geologic materials indicate that several geophysical methods are technically feasible for detection of subsurface voids in Ohio, but ease of use and interpretation varies widely between the methods. Ground-penetrating radar is the most rapid and cost-effective method for collection of subsurface data in areas associated with voids under roadways. Electrical resistivity, gravity, or seismic reflection methods have applications for direct delineation of voids, but data-collection and analytical procedures are more time consuming. Electrical resistivity, electromagnetic, or magnetic methods may be useful in locating areas where conductive material, such as rail lines, are present in abandoned underground coal mines. Other electrical methods include spontaneous potential and very low frequency (VLF); these latter two methods are considered unlikely candidates for locating underground voids in Ohio. Results of ground-penetrating radar surveys at three highway sites indicate that subsurface penetration varies widely with geologic material type and amount of cultural interference. Two highway sites were chosen over abandoned underground coal mines in eastern Ohio. A third site in western Ohio was chosen in an area known to be underlain by naturally occurring voids in lime stone. Ground-penetrating radar surveys at Interstate 470, in Belmont County, Ohio, indicate subsurface penetration of less than 15 feet over a mined coal seam that was known to vary in depth from 0 to 40 feet. Although no direct observations of voids were made, anomalous areas that may be related to collapse structures above voids were indicated. Cultural interference dominated the radar records at Interstate 70, Guernsey County, Ohio

  10. Studies on polyphenol content, activities and isozymes of polyphenol oxidase and peroxidase during air-curing in three tobacco types.

    PubMed

    Sheen, S J; Calvert, J

    1969-02-01

    The change in polyphenol content in the primed leaves of burley, flue-cured, and Turkish tobaccos during air-curing was related to the activities and isozymes of polyphenol oxidase and peroxidase. The quantity of chlorogenic acid was rapidly reduced during the first week of curing. The decrease in rutin content during curing was less significant, especially when the concentration of chlorogenic acid was high in leaf tissues. This result was further confirmed by in vitro assays with partially purified tobacco polyphenol oxidase.The polyphenol oxidase activity did not differ at any stage of curing in the 3 tobaccos. When the activity was measured by the oxidation of 3,4-dihydroxyphenylalanine it rose rapidly during the first day of curing and then decreased sharply so that in the fully cured leaf only 15% activity remained. The increase in activity was not observed when chlorogenic acid was used as the substrate. A similar level of peroxidase activity was found in the 3 tobaccos before curing. Peroxidase activities increased rapidly during the first 24 hr of curing, declined thereafter, and remained highest in the flue-cured tobacco, less in the Turkish line, and least in the burley at the end of curing process.By polyacrylamide gel block electrophoresis, 10 peroxidase isozyme bands, 2 cationic and 8 anionic, appeared identical in all 3 tobaccos. When catechol replaced benzidine-2 HCl as the electron donor, 1 cationic and 2 anionic peroxidase isozymes did not form. Of interest is that the same 10 peroxidase isozyme bands also exhibited polyphenol oxidase activities when treated with 3,4-dihydroxyphenylalanine or chlorogenic acid. Results suggest that in the crude tobacco leaf extract the peroxidase and polyphenol oxidase may associate as protein complexes, and peroxidase isozymes may differ in electron-donor requirements. Isozyme patterns for both oxidases at various curing intervals differed only quantitatively.

  11. Climatic and insolation control on the high-resolution total air content in the NGRIP ice core

    NASA Astrophysics Data System (ADS)

    Eicher, O.; Baumgartner, M.; Schilt, A.; Schmitt, J.; Schwander, J.; Stocker, T. F.; Fischer, H.

    2015-11-01

    Because the total air content (TAC) of polar ice is directly affected by the atmospheric pressure, its record in polar ice cores was considered as a proxy for past ice sheet elevation changes. However the Antarctic ice core TAC record is known to also contain an insolation signature, although the underlying physical mechanisms are still a matter of debate. Here we present a high-resolution TAC record over the whole North Greenland Ice Core Project ice core, covering the last 120 000 years, which independently supports an insolation signature in Greenland. Wavelet analysis reveals a clear precession and obliquity signal similar to previous findings on Antarctic TAC, with different insolation history. In our high-resolution record we also find a decrease of 3-5 % (3-4.2 mL kg-1) in TAC as a response to Dansgaard-Oeschger-Events (DO-events). TAC starts to decrease in parallel to increasing Greenland surface temperature and slightly before CH4 reacts to the warming, but also shows a two-step decline that lasts for several centuries into the warm phase/interstadial. The TAC response is larger than expected considering only local temperature and atmospheric pressure as a driver, pointing to transient firnification response caused by the accumulation-induced increase in the load on the firn at bubble close-off, while temperature changes deeper in the firn are still small.

  12. Experimental study of void behavior in a suppression pool of a boiling water reactor during the blowdown period of a loss of coolant accident

    NASA Astrophysics Data System (ADS)

    Rassame, Somboon

    The possible failure of an Emergency Core Cooling System (ECCS) train due to a large amount of entrained gas in the ECCS pump suction piping in a Loss of Coolant Accident (LOCA) is one of the potential engineering problems faced in a Boiling Water Reactor (BWR) power plant. To analyze potential gas intrusion into the ECCS pump suction piping, the study of void behavior in the Suppression Pool (SP) during the LOCA is necessary. The void fraction distribution and void penetration are considered as the key parameters in the problem analysis. Two sets of experiments, namely, steady-state tests and transient tests were conducted using the Purdue University Multi-Dimensional Integral Test Assembly for ESBWR application (PUMA-E) to study void behavior in the SP during the blowdown. The design of the test apparatus used is based on the scaling analysis from a prototypical BWR containment (MARK-I) with consideration of the downcomer size, the SP water level, and the downcomer water submergence depth. Several instruments were installed to obtain the required experimental data, such as inlet gas volumetric flow, void fraction, pressure, and temperature. For the steady-state tests, the air was injected through a downcomer pipe in the SP in order to simulate the physical phenomena in the SP during the initial blowdown of LOCA. Thirty tests were performed with two different downcomer sizes (0.076 and 0.102 m), various air volumetric flow rates or flux (0.003 to 0.153 m3/s or 0.5 to 24.7 m/s), initial downcomer void conditions (fully filled with water, partially void, and completely void) and air velocity ramp rates (one to two seconds). Two phases of the experiment were observed, namely, the initial phase and the quasi-steady phase. The initial phase produced the maximum void penetration depth; and the quasi-steady phase showed less void penetration with oscillation in the void penetration. The air volumetric flow rate was found to have a minor effect on the void fraction

  13. Void ellipticity distribution as a probe of cosmology.

    PubMed

    Park, Daeseong; Lee, Jounghun

    2007-02-23

    Cosmic voids refer to the large empty regions in the Universe with a very low number density of galaxies. Voids are likely to be severely disturbed by the tidal effect from the surrounding dark matter. We derive a completely analytic model for the void ellipticity distribution from physical principles. We use the spatial distribution of galaxies in a void as a measure of its shape, tracking the trajectory of the void galaxies under the influence of the tidal field using Lagrangian perturbation theory. Our model implies that the void ellipticity distribution depends sensitively on the cosmological parameters. Testing our model against the high-resolution Millennium Run simulation, we find excellent quantitative agreements of the analytic predictions with the numerical results.

  14. Void growth in an elastic-plastic medium.

    NASA Technical Reports Server (NTRS)

    Needleman, A.

    1972-01-01

    The uniaxial deformation of an elastic-plastic medium containing a doubly periodic square array of circular cylindrical voids is studied under plane-strain conditions. Both the effects of geometrical nonlinearities resulting from large deformation and physical nonlinearities arising from plastic material behavior are included in formulating the problem. A variational principle is used as the basis for implementing a finite-element solution. Results are obtained for the change in void shape and size under increasing overall strain, the overall tensile behavior of the material with voids, and the development of the plastic zone about a void.

  15. Galaxy Number Counts as a Probe for Voids

    NASA Astrophysics Data System (ADS)

    Bucklein, B. K.; Moody, J. W.; Hintz, E. G.

    2010-10-01

    We investigate the use of galaxy number counts (GNC) to probe for voids. As a first step, we create a toy model of a volume of space with a random distribution of galaxies. We then create voids in this distribution at different distances and with varying widths. As a diagnostic of the voids, we plot the log of the number of galaxies brighter than a given apparent magnitude versus the apparent magnitude. The technique turns out to be very sensitive to the distance, the size, and the type of void.

  16. Wettability of elastomeric impression materials and voids in gypsum casts.

    PubMed

    Cullen, D R; Mikesell, J W; Sandrik, J L

    1991-08-01

    Numerous factors are involved in making an accurate void-free dental artificial stone cast or die. The relationship of the wettability of an elastomeric impression material and its interaction with the gypsum slurry is an important factor. This study examined the relative "pourability" of several impression materials by counting the number of resultant voids in artificial stone casts containing 48 point angles. Those elastomers that exhibited the lowest contact angle with water produced artificial stone casts with the fewest voids. Surfactants applied to the impression material significantly reduced the number of voids in artificial stone casts, as did modified elastomers designated by the manufacturer as hydrophilic.

  17. Quantifying Effects of Voids in Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    Randomness in woven ceramic matrix composite architecture has been found to cause large variability in stiffness and strength. The inherent voids are an aspect of the architecture that may cause a significant portion of the variability. A study is undertaken to investigate the effects of many voids of random sizes and distributions. Response surface approximations were formulated based on void parameters such as area and length fractions to provide an estimate of the effective stiffness. Obtaining quantitative relationships between the properties of the voids and their effects on stiffness of ceramic matrix composites are of ultimate interest, but the exploratory study presented here starts by first modeling the effects of voids on an isotropic material. Several cases with varying void parameters were modeled which resulted in a large amount of variability of the transverse stiffness and out-of-plane shear stiffness. An investigation into a physical explanation for the stiffness degradation led to the observation that the voids need to be treated as an entity that reduces load bearing capabilities in a space larger than what the void directly occupies through a corrected length fraction or area fraction. This provides explanation as to why void volume fraction is not the only important factor to consider when computing loss of stiffness.

  18. Investigations on Void Formation in Composite Molding Processes and Structural Damping in Fiber-Reinforced Composites with Nanoscale Reinforcements

    NASA Astrophysics Data System (ADS)

    DeValve, Caleb Joshua

    Fiber-reinforced composites (FRCs) offer a stronger and lighter weight alternative to traditional materials used in engineering components such as wind turbine blades and rotorcraft structures. Composites for these applications are often fabricated using liquid molding techniques, such as injection molding or resin transfer molding. One significant issue during these processing methods is void formation due to incomplete wet-out of the resin within the fiber preform, resulting in discontinuous material properties and localized failure zones in the material. A fundamental understanding of the resin evolution during processing is essential to designing processing conditions for void-free filling, which is the first objective of the dissertation. Secondly, FRCs used in rotorcraft experience severe vibrational loads during service, and improved damping characteristics of the composite structure are desirable. To this end, a second goal is to explore the use of matrix-embedded nanoscale reinforcements to augment the inherent damping capabilities in FRCs. The first objective is addressed through a computational modeling and simulation of the infiltrating dual-scale resin flow through the micro-architectures of woven fibrous preforms, accounting for the capillary effects within the fiber bundles. An analytical model is developed for the longitudinal permeability of flow through fibrous bundles and applied to simulations which provide detailed predictions of local air entrapment locations as the resin permeates the preform. Generalized design plots are presented for predicting the void content and processing time in terms of the Capillary and Reynolds Numbers governing the molding process. The second portion of the research investigates the damping enhancement provided to FRCs in static and rotational configurations by different types and weight fractions of matrix-embedded carbon nanotubes (CNTs) in high fiber volume fraction composites. The damping is measured using

  19. Influence of gas pressure in the voids during charging on the piezoelectricity of ferroelectrets

    NASA Astrophysics Data System (ADS)

    Qiu, Xunlin; Mellinger, Axel; Gerhard, Reimund

    2008-02-01

    Cellular polypropylene ferroelectrets were subjected to vacuum and high air pressures. The capacitance of the samples was measured as a way to monitor their thickness. It was found that both in vacuum and in high-pressure air, the thickness of the samples recovers to its original value after a sufficient storage time (typically, several hours), indicating that the internal and external pressures equalize as a result of gas diffusion. Optimal piezoelectricity is achieved by charging at a pressure of 170kPa, which is explained by means of the void-height distribution function in combination with Townsend's model of the Paschen breakdown.

  20. Void swelling in high dose ion-irradiated reduced activation ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Monterrosa, Anthony M.; Zhang, Feifei; Huang, Hao; Yan, Qingzhi; Jiao, Zhijie; Was, Gary S.; Wang, Lumin

    2015-07-01

    To determine the void swelling resistance of reduced-activation ferritic-martensitic steels CNS I and CNS II at high doses, ion irradiation was performed up to 188 dpa (4.6 × 1017 ion/cm2) at 460 °C using 5 MeV Fe++ ions. Helium was pre-implanted at levels of 10 and 100 appm at room temperature to investigate the role of helium on void swelling. Commercial FM steel T91 was also irradiated in this condition and the swelling results are of included in this paper as a reference. Voids were observed in all conditions. The 9Cr CNS I samples implanted with 10 appm helium exhibited lower swelling than 9Cr T91 irradiated at the same condition. The 12Cr CNS II with 10 and 100 appm helium showed significantly lower swelling than CNS I and T91. The swelling rate for CNS I and CNS II were determined to be 0.02%/dpa and 0.003%/dpa respectively. Increasing the helium content from 10 to 100 appm shortened the incubation region and increased the void density but had no effect on the swelling rates.

  1. Development of a low void polyimide resin for autoclave processing of glass and graphite reinforced composites.

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J.; Sheppard, C. H.; Burns, E. A.

    1971-01-01

    Experimental studies are described in which new A-type polyimide prepolymer chemical modifications were investigated with the aim of increasing the melt phase duration and temperature range permitting autoclave processing, yet retaining the addition-type cure mechanism required for low-void content composites. Several modification candidates were examined, and one specific formulation was selected for detailed investigation. This A-type polyimide prepolymer formulation is shown to possess the desired characteristics.

  2. Formation of Voids from Negative Density Perturbations

    NASA Astrophysics Data System (ADS)

    de Araujo, J. C. N.; Opher, R.

    1990-11-01

    RESUMEN. Se estudia la formaci6n de huecos a partir de un espectro negativo de perturbaciones, tomando en cuenta la expansi6n del Universo, arrastre por fotones, enfriamiento por fotones, fotoionizaci6n, ioniza- ci6n colisional, enfriamiento Lyman a y la formaci6n y enfriamiento de moleculas H2. Nuestros resultados predicen la existencia de regiones 1/10 de Ia densidad promedio para regiones de masa lO - 1O10M . ABSTRACT. In the present paer we study the formation of voids from a negative spectrum of perturbations taking into account the expansion of the Universe, photon-drag, photon-cooling, photoionization, collisional ionization, Lyman a cooling and the formation and cooling of 112 molecules. Our results predict the existence of regions 1/10 the average density for regions of mass 1O - 1O10M@ : CLUSTERS-GALAXIES - COSMOLOGY

  3. Subsurface void detection using seismic tomographic imaging

    SciTech Connect

    Gritto, Roland

    2003-06-26

    Tomographic imaging has been widely used in scientific and medical fields to remotely image media in a nondestructive way. This paper introduces a spectrum of seismic imaging applications to detect and characterize voids in coal mines. The application of seismic waves to detect changes in coal relies on two types of waves: body waves refracted along the interface between coal and bedrock (i.e., refracted P-waves) and channel waves that propagate directly through the coal (dispersive wave trains of the Rayleigh or Love type). For example, a P-wave tomography study to find underlying old mine workings in a coal mine in England, produced velocity patterns that revealed increases in velocity where high stress concentrations occur in the rock, which are most likely connected to old pillars left in support of the old working areas. At the same time, low velocities were found in areas of low stress concentrations, which are related to roof collapses indicating the locations of mined areas below. The application of channel wave tomography to directly image the presence of gaseous CO{sub 2} in a low velocity oil reservoir showed that the injected CO{sub 2} followed an ancient flow channel in the reservoir migrating from the injector to the producer well. The study showed how channel waves are preferable over refracted P-waves, as the latter were only marginally affected by the presence of the gas in the low-velocity channel. Similar approaches show great promise for the detection of voids in coal mines. Finally, a newly developed technique, based on scattering theory, revealed that the location and the size of a subsurface cavity could be accurately determined even in the presence of strong correlated and uncorrelated noise.

  4. Changes in tocopherol and plastochromanol-8 contents in seeds and oil of oilseed rape (Brassica napus L.) during storage as influenced by temperature and air oxygen.

    PubMed

    Goffman, F D; Möllers, C

    2000-05-01

    The changes in tocopherol and plastochromanol-8 contents in seeds and oil of oilseed rape (Brassica napus L.) were studied during a storage period of 24 weeks at different incubation temperatures and exposure to air oxygen (open and closed flasks). In the extracted oil, total tocopherol content remained unaltered at 5 and 20 degrees C throughout the 24 weeks of storage. At 40 degrees C, a beginning degradation was observed already after 4 weeks in both open and closed flasks; the alpha-tocopherol content was affected most, followed by gamma-tocopherol and plastochromanol-8. After 16 weeks at 40 degrees C, the total tocopherol content in the oil was reduced by more than 90%. In intact seeds, no tocopherol degradation was observed; only the seeds incubated at 40 degrees C and in open flasks showed slightly lower tocopherol contents. However, the analysis of the tocopherol composition in the stored seeds showed a decrease in the alpha-tocopherol content and an increase in the gamma-tocopherol content, which resulted in a decreasing alpha-/gamma-tocopherol ratio. This trend was most apparent at 40 degrees C and after 24 weeks of storage. A reduction of plastochromanol-8 occurred only at 40 degrees C and was more pronounced in open flasks. At 40 degrees C and in closed flasks a gradual increase in the content of alpha-tocotrienol was observed, a compound normally not accumulated in rapeseed.

  5. 22 CFR 709.8 - Procedure for voiding suspensions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 2 2011-04-01 2009-04-01 true Procedure for voiding suspensions. 709.8 Section 709.8 Foreign Relations OVERSEAS PRIVATE INVESTMENT CORPORATION ADMINISTRATIVE PROVISIONS FOREIGN CORRUPT PRACTICES ACT OF 1977 § 709.8 Procedure for voiding suspensions. Upon receipt by OPIC from...

  6. 22 CFR 709.8 - Procedure for voiding suspensions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Procedure for voiding suspensions. 709.8 Section 709.8 Foreign Relations OVERSEAS PRIVATE INVESTMENT CORPORATION ADMINISTRATIVE PROVISIONS FOREIGN CORRUPT PRACTICES ACT OF 1977 § 709.8 Procedure for voiding suspensions. Upon receipt by OPIC from...

  7. Locating voids beneath pavement using pulsed electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Steinway, W. J.; Echard, J. D.; Luke, C. M.

    1981-11-01

    The feasibility of using pulsed electromagnetic wave technology for locating and sizing voids beneath reinforced and nonreinforced portland cement concrete pavements is determined. The data processing techniques developed can be implemented to provide information for void depth and sizing to + or - 1/2 in. and spatial location within + or - 6 in. A very short pulse radar directly connected to a microcomputer was chosen as the equipment necessary to obtain measurements. This equipment has the required accuracy and reliability, and is a cost effective solution for the void locating problem. The radar provides a signal return from voids that has unique characteristics that can be examined to provide information regarding the location, depth, and shape of the void. The microcomputer provides a means of real time processing to extract the information from the radar signal return and record the results. Theoretical modeling of signal returns from voids led to suitable techniques for locating and sizing voids beneath the pavement. Analysis and application of these techniques to radar measurements verified the theoretical predictions that radar can be used to determine the location, size, and shape of actual voids.

  8. Lensing measurements of the mass distribution in SDSS voids

    NASA Astrophysics Data System (ADS)

    Clampitt, Joseph; Jain, Bhuvnesh

    2015-12-01

    We measure weak lensing mass profiles of voids from a volume-limited sample of SDSS Luminous Red Galaxies (LRGs). We find voids using an algorithm designed to maximize the lensing signal by dividing the survey volume into 2D slices, and then finding holes in this 2D distribution of LRGs. We perform a stacked shear measurement on about 20 000 voids with radii between 15 and 55 Mpc h-1, and redshifts between 0.16 and 0.37. We measure the characteristic radial shear signal of voids with a signal to noise of 7. The mass profile corresponds to a fractional underdensity of about -0.4 inside the void radius and a slow approach to the mean density indicating a partially compensated void structure. We compare our measured shape and amplitude with the predictions of Krause et al. Voids in the galaxy distribution have been extensively modelled using simulations and measured in the SDSS. We discuss how the addition of void mass profiles can enable studies of galaxy formation and cosmology.

  9. The relationship between void waves and flow regime transition

    SciTech Connect

    Lahey, R.T. Jr.; Drew, D.A.; Kalkach-Navarro, S.; Park, J.W.

    1992-12-31

    The results of an extensive experimental and analytical study on the relationship between void waves and flow regime transition are presented, in particular, the bubbly/slug flow regime transition. It is shown that void wave instability signals a flow regime transition.

  10. High gain durable anti-reflective coating with oblate voids

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze'ev

    2016-06-28

    Disclosed herein are single layer transparent coatings with an anti-reflective property, a hydrophobic property, and that are highly abrasion resistant. The single layer transparent coatings contain a plurality of oblate voids. At least 1% of the oblate voids are open to a surface of the single layer transparent coatings.

  11. Void nucleation in spheroidized steels during tensile deformation

    SciTech Connect

    Fisher, Jr, J R

    1980-04-01

    An investigation was conducted to determine the effects of various mechanical and material parameters on void formation at cementite particles in axisymmetric tensile specimens of spheroidized plain carbon steels. Desired microstructures for each of three steel types were obtained. Observations of void morphology with respect to various microstructural features were made using optical and scanning electron microscopy.

  12. Measuring the growth rate of structure around cosmic voids

    NASA Astrophysics Data System (ADS)

    Hawken, A. J.; Michelett, D.; Granett, B.; Iovino, A.; Guzzo, L.

    2016-10-01

    Using an algorithm based on searching for empty spheres we identified 245 voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS). We show how by modelling the anisotropic void-galaxy cross correlation function we can probe the growth rate of structure.

  13. Effect of ultrasound and blanching pretreatments on polyacetylene and carotenoid content of hot air and freeze dried carrot discs.

    PubMed

    Rawson, A; Tiwari, B K; Tuohy, M G; O'Donnell, C P; Brunton, N

    2011-09-01

    The effect of ultrasound and blanching pretreatments on polyacetylene (falcarinol, falcarindiol and falcarindiol-3-acetate) and carotenoid compounds of hot air and freeze dried carrot discs was investigated. Ultrasound pretreatment followed by hot air drying (UPHD) at the highest amplitude and treatment time investigated resulted in higher retention of polyacetylenes and carotenoids in dried carrot discs than blanching followed by hot air drying. Freeze dried samples had a higher retention of polyacetylene and carotenoid compounds compared to hot air dried samples. Color parameters were strongly correlated with carotenoids (p<0.05). This study shows that ultrasound pretreatment is a potential alternative to conventional blanching treatment in the drying of carrots.

  14. DETECTION OF MOLECULAR GAS IN VOID GALAXIES: IMPLICATIONS FOR STAR FORMATION IN ISOLATED ENVIRONMENTS

    SciTech Connect

    Das, M.; Honey, M.; Saito, T.; Iono, D.; Ramya, S.

    2015-12-10

    We present the detection of molecular gas from galaxies located in nearby voids using the CO(1–0) line emission as a tracer. The observations were performed using the 45 m single dish radio telescope of the Nobeyama Radio Observatory. Void galaxies lie in the most underdense parts of our universe and a significant fraction of them are gas rich, late-type spiral galaxies. Although isolated, they have ongoing star formation but appear to be slowly evolving compared to galaxies in denser environments. Not much is known about their star formation properties or cold gas content. In this study, we searched for molecular gas in five void galaxies. The galaxies were selected based on their relatively high IRAS fluxes or Hα line luminosities, both of which signify ongoing star formation. All five galaxies appear to be isolated and two lie within the Bootes void. We detected CO(1–0) emission from four of the five galaxies in our sample and their molecular gas masses lie between 10{sup 8} and 10{sup 9} M{sub ⊙}. We conducted follow-up Hα imaging observations of three detected galaxies using the Himalayan Chandra Telescope and determined their star formation rates (SFRs) from their Hα fluxes. The SFR varies from 0.2 to 1 M{sub ⊙} yr{sup −1}; which is similar to that observed in local galaxies. Our study indicates that although void galaxies reside in underdense regions, their disks contain molecular gas and have SFRs similar to galaxies in denser environments. We discuss the implications of our results.

  15. Voids and the Cosmic Web: cosmic depression & spatial complexity

    NASA Astrophysics Data System (ADS)

    van de Weygaert, Rien

    2016-10-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe nature of dark energy, while their substructure and galaxy population provides a direct key to thenature of dark matter. Also, the pristine environment of void interiors is an important testing groundfor our understanding of environmental influences on galaxy formation and evolution. In this paper, we reviewthe key aspects of the structure and dynamics ofvoids, with a particular focus on the hierarchical evolution of the void population. We demonstratehow the rich structural pattern of the Cosmic Web is related to the complex evolution and buildupof voids.

  16. The cosmic web in CosmoGrid void regions

    NASA Astrophysics Data System (ADS)

    Rieder, Steven; van de Weygaert, Rien; Cautun, Marius; Beygu, Burcu; Portegies Zwart, Simon

    2016-10-01

    We study the formation and evolution of the cosmic web, using the high-resolution CosmoGrid ΛCDM simulation. In particular, we investigate the evolution of the large-scale structure around void halo groups, and compare this to observations of the VGS-31 galaxy group, which consists of three interacting galaxies inside a large void. The structure around such haloes shows a great deal of tenuous structure, with most of such systems being embedded in intra-void filaments and walls. We use the Nexus+} algorithm to detect walls and filaments in CosmoGrid, and find them to be present and detectable at every scale. The void regions embed tenuous walls, which in turn embed tenuous filaments. We hypothesize that the void galaxy group of VGS-31 formed in such an environment.

  17. Distinguishing f(R) gravity with cosmic voids

    NASA Astrophysics Data System (ADS)

    Zivick, P.; Sutter, P. M.

    2016-10-01

    We use properties of void populations identified in N-body simulations to forecast the ability of upcoming galaxy surveys to differentiate models of f(R) gravity from \\lcdm cosmology. We analyze simulations designed to mimic the densities, volumes, and clustering statistics of upcoming surveys, using the public {\\tt VIDE} toolkit. We examine void abundances as a basic probe at redshifts 1.0 and 0.4. We find that stronger f(R) coupling strengths produce voids up to ~20% larger in radius, leading to a significant shift in the void number function. As an initial estimate of the constraining power of voids, we use this change in the number function to forecast a constraint on the coupling strength of Δ fR0 = 10-5.

  18. Measuring baryon acoustic oscillations from the clustering of voids

    NASA Astrophysics Data System (ADS)

    Liang, Yu; Zhao, Cheng; Chuang, Chia-Hsun; Kitaura, Francisco-Shu; Tao, Charling

    2016-07-01

    We investigate the necessary methodology to optimally measure the baryon acoustic oscillation (BAO) signal from voids, based on galaxy redshift catalogues. To this end, we study the dependence of the BAO signal on the population of voids classified by their sizes. We find for the first time the characteristic features of the correlation function of voids including the first robust detection of BAOs in mock galaxy catalogues. These show an anti-correlation around the scale corresponding to the smallest size of voids in the sample (the void exclusion effect), and dips at both sides of the BAO peak, which can be used to determine the significance of the BAO signal without any priori model. Furthermore, our analysis demonstrates that there is a scale-dependent bias for different populations of voids depending on the radius, with the peculiar property that the void population with the largest BAO significance corresponds to tracers with approximately zero bias on the largest scales. We further investigate the methodology on an additional set of 1000 realistic mock galaxy catalogues reproducing the SDSS-III/BOSS CMASS DR11 data, to control the impact of sky mask and radial selection function. Our solution is based on generating voids from randoms including the same survey geometry and completeness, and a post-processing cleaning procedure in the holes and at the boundaries of the survey. The methodology and optimal selection of void populations validated in this work have been used to perform the first BAO detection from voids in observations, presented in a companion paper.

  19. Seismic Techniques for Subsurface Voids Detection

    NASA Astrophysics Data System (ADS)

    Gritto, Roland; Korneev, Valeri; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

    2016-04-01

    A major hazards in Qatar is the presence of karst, which is ubiquitous throughout the country including depressions, sinkholes, and caves. Causes for the development of karst include faulting and fracturing where fluids find pathways through limestone and dissolve the host rock to form caverns. Of particular concern in rapidly growing metropolitan areas that expand in heretofore unexplored regions are the collapse of such caverns. Because Qatar has seen a recent boom in construction, including the planning and development of complete new sub-sections of metropolitan areas, the development areas need to be investigated for the presence of karst to determine their suitability for the planned project. In this paper, we present the results of a study to demonstrate a variety of seismic techniques to detect the presence of a karst analog in form of a vertical water-collection shaft located on the campus of Qatar University, Doha, Qatar. Seismic waves are well suited for karst detection and characterization. Voids represent high-contrast seismic objects that exhibit strong responses due to incident seismic waves. However, the complex geometry of karst, including shape and size, makes their imaging nontrivial. While karst detection can be reduced to the simple problem of detecting an anomaly, karst characterization can be complicated by the 3D nature of the problem of unknown scale, where irregular surfaces can generate diffracted waves of different kind. In our presentation we employ a variety of seismic techniques to demonstrate the detection and characterization of a vertical water collection shaft analyzing the phase, amplitude and spectral information of seismic waves that have been scattered by the object. We used the reduction in seismic wave amplitudes and the delay in phase arrival times in the geometrical shadow of the vertical shaft to independently detect and locate the object in space. Additionally, we use narrow band-pass filtered data combining two

  20. Postmortem volumetric CT data analysis of pulmonary air/gas content with regard to the cause of death for investigating terminal respiratory function in forensic autopsy.

    PubMed

    Sogawa, Nozomi; Michiue, Tomomi; Ishikawa, Takaki; Kawamoto, Osamu; Oritani, Shigeki; Maeda, Hitoshi

    2014-08-01

    Postmortem CT (PMCT) is useful to investigate air/gas distribution and content in body cavities and viscera. The present study investigated the procedure to estimate total lung air/gas content and aeration ratio as possible indices of terminal respiratory function, using three-dimensional (3-D) PMCT data analysis of forensic autopsy cases without putrefactive gas formation (within 3 days postmortem, n=75), and analyzed the volumetric data with regard to the cause of death. When 3-D bilateral lung images were reconstructed using an image analyzer, combined lung volume was larger in drowning (n=12) than in alcohol/sedative-hypnotic intoxication (n=8) and sudden cardiac death (SCD; n=10), and intermediate in other cases, including mechanical asphyxiation (n=12), fire fatalities due to burns (n=6) and carbon monoxide intoxication (n=7), fatal methamphetamine abuse (n=7), hyperthermia (heatstroke; n=6) and fatal hypothermia (cold exposure; n=7). Air/gas content of the lung as detected using HU interval between -2000 and -400 ('effective' lung aeration areas) and between -2000 and -191 (total lung aeration areas) as well as the ratios to total lung volume ('effective' and total lung aeration ratios, respectively) was higher in mechanical asphyxiation, drowning, fatal burns and hypothermia (cold exposure) than in SCD, and was intermediate in other cases. 'Effective' and total lung aeration ratios may be useful for comparisons between specific causes of death to discriminate between hypothermia (cold exposure) and drug intoxication, and between SCD and other causes of death, respectively. These findings provide interesting insights into potential efficacy of PMCT data analyses of lung volume and CT density as well as lung air/gas content and aeration ratio with regard to the cause of death, as possible indicators of terminal respiratory function, as part of virtual autopsy of the viscera in situ.

  1. Effect of air flow rate on the polyphenols content and antioxidant capacity of convective dried cactus pear cladodes (Opuntia ficus indica).

    PubMed

    Gallegos-Infante, José-Alberto; Rocha-Guzman, Nuria-Elizabeth; González-Laredo, Ruben-Francisco; Reynoso-Camacho, Rosalia; Medina-Torres, Luis; Cervantes-Cardozo, Veronica

    2009-01-01

    The interest in nopal has encouraged the use of dehydration; there are few studies about the effect of process parameters on the nopal polyphenol content and antioxidant activity. The objective of the present work was to evaluate the effect of air-drying flow rates on the amount and antioxidant capacity of extracts of Opuntia ficus indica cladodes. Nopal was dried at 45 degrees C and air flow rates of 3 and 5 m/sec. Samples were analyzed for moisture, total polyphenol, flavonoid, and flavonol contents, chain-breaking activity, inhibition of low-density lipoprotein and deoxyribose oxidation. Nopal drying at an air flow rate of 3 m/sec showed higher values of phenols, flavonoids and flavonols. The best value of low-density lipoprotein inhibition and deoxyribose was found at 1,000 microg/ml. The air flow rate affected the amount of polyphenols and the OH( . ) radical scavenging, but did not modify the chain-breaking activity and the low-density lipoprotein inhibition activity.

  2. Do symptoms of voiding dysfunction predict urinary retention?

    PubMed Central

    ADELOWO, Amos O.; HACKER, Michele R.; MODEST, Anna MERPORT; ELKADRY, Eman A.

    2012-01-01

    Objectives We assessed the relationship between symptoms of voiding dysfunction and elevated post void urinary residual (PVR). Methods Cross-sectional study of women presenting for initial evaluation from February through July 2011. Charts were reviewed for demographics, voiding dysfunction symptoms, and examination findings. Urinary retention was defined as PVR ≥100cc. Data are presented as median (interquartile range) or proportion; test characteristics are reported with 95% confidence intervals. Results Of 641 eligible women, 57 (8.9%) had urinary retention. Of these, 32 (56.1%) had at least one symptom of voiding dysfunction, most commonly sensation of incomplete emptying (30.1%). Sensitivity and positive predictive values of voiding dysfunction symptoms were low. Of 254 women reporting voiding symptoms, most (87.5%) had PVR<100 and were significantly more likely to have other pelvic floor symptoms and findings. Conclusions Patient symptoms do not predict urinary retention. PVR should be measured and other causes of voiding dysfunction symptoms should be considered. PMID:23143428

  3. Subchannel void fraction prediction via drift-flux analysis

    SciTech Connect

    Khan, H.J.; Kosaly, G.

    1986-10-01

    Void fraction calculations have been performed using the subchannel drift-flux code CANAL. Using void and flow distributions in rod bundle geometry, a value of C/sub 0/ has been estimated for bundle-averaged void fraction calculation in one-dimensional approximations. Successful prediction of the average void fraction is observed for the annular rod bundle geometry of the FRIGG experiment. In order to perform subchannel void fraction calculation, a C/sub 0/ model has been developed for one-dimensional subchannel geometry. The implicit form of the C/sub 0/ model developed accounts for void and flow conditions in the adjacent subchannels existing at the common interfaces, i.e., at the gap spacing between the subchannels. It appears that the magnitude of C/sub 0/ varies between subchannels (annular rings of FRIGG geometry) but remains almost constant within each subchannel. Good agreement is observed between prediction and data for subchannel void fractions in axially uniform and nonuniform heated rod bundles.

  4. Influence of Grain Boundary Properties and Orientation on Void Nucleation

    SciTech Connect

    Fensin, Saryu Jindal

    2016-03-01

    For ductile metals, dynamic fracture during shock loading is thought to occur through void nucleation, growth, and then coalescence that leads to material failure. Particularly for high purity metals, it has been observed by numerous investigators that, under incipient spall conditions, voids appear to heterogeneously nucleate at some grain boundaries, but not others. Several factors can affect the void nucleation stress at a grain boundary, such as grain boundary structure, orientation with respect to the loading direction, energy and excess volume, in addition to its interactions with dislocations. In this work, we focus on the influence of loading direction with respect to the grain boundary plane and grain boundary properties such as energy and excess volume on the stress required for void nucleation of a grain boundary, in copper from moleculardynamics simulations. Flyer plate simulations were carried out for four boundary types with different energies and excess volumes. These boundaries were chosen as model systems to represent various boundaries observed in “real” materials. Simulations indicate that there is no direct correlation between the void nucleation stress at a boundary and either its energy and excess volume. This result suggests that average properties of grain boundaries alone are not sufficient indicators of the spall strength of a boundary and perhaps local boundary properties need to be taken into account in order to predict its susceptibility to void nucleation for broad ranges of materials. We also present both experimental and simulation results corresponding to the affect of orientation on void nucleation.

  5. The spreading of a void on a facet during electromigration

    SciTech Connect

    Chu, X.; Bauer, C.L.; Mullins, W.W.; Klinger, L.M.

    1997-07-01

    A void of cross sectional area A may spread perpendicular to the applied electric field E{sub a} during electromigration because its leading surface develops a facet whose advance is limited by the supply of steps. If the facet is immobile (no step source) and the remaining surface is free to move, and if E{sub a}A is less than a threshold value, then the void assumes a stationary elongated shape dictated by a balance between capillarity and electric field. If E{sub a}A exceeds the threshold value, however, a balance is no longer possible, and the void spreads along the facet without arrest. If the facet has limited mobility, a balance is possible for all values of E{sub a}A, resulting in an elongated moving steady-state shape. The treatment simplifies the void shape as rectangular but preserves the essential features of capillarity and surface electromigration. The authors argue that the motion of a facet on a void along the outward normal requires defects (e.g., intersecting screw dislocations) that act as step sources since homogeneous nucleation of steps on the facet is expected to be negligible. Since voids in fine-line interconnects are often observed to be partially faceted, restricted void motion and resultant spreading which depend sensitively on crystallographic features, such as defect structure and grain orientation, may indeed limit the lifetime of fine-line interconnects in electronic devices.

  6. Void evolution and porosity under arsenic ion irradiation in GaAs1‑x Sb x alloys

    NASA Astrophysics Data System (ADS)

    Alkhaldi, H. S.; Kluth, P.; Kremer, F.; Lysevych, M.; Li, L.; Ridgway, M. C.; Williams, J. S.

    2017-03-01

    We have studied the formation of porosity in crystalline GaAs0.25Sb0.75 and GaAs0.5Sb0.5 alloys under irradiation with 140 keV As‑ ions over a wide range of temperature (‑180 to 400 °C) and ion fluences ranging from 1× {{10}13} to 2× {{10}17} ions cm‑2. The GaAs0.25Sb0.75 alloy showed only little swelling (in comparison with GaSb), with void formation and sputtering both playing an important role in the materials modification. The initiation of voids and their evolution in the alloy strongly depends on the ion fluence and irradiation temperature, as well as the As content in the alloy. Porosity is largely suppressed in the GaAs0.25Sb0.75 alloy, with the major change being void formation. For the GaAs0.5Sb0.5 alloy, it was rendered amorphous with no apparent pores or void structures and only sputtering effects were observed at high ion fluence. In addition, the transformations from crystalline to amorphous and to a void or a porous structure occurred simultaneously in the GaAs0.25Sb0.75 alloy. The mechanisms responsible for such changes are consistent with point defect movement and segregation.

  7. Void fraction correlations in two-phase horizontal flow

    SciTech Connect

    Papathanassiou, G.; Maeder, P.F.; DiPippo, R.; Dickinson, D.A.

    1983-05-01

    This study examines some physical mechanisms which impose limits on the possible existence of two-phase flow in a horizontal pipe. With the aid of this analysis and the use of the Martinelli variable, X, a method is developed which determines the range of possible void fractions for a given two-phase flow. This method affords a means of direct comparison among void fraction correlations, as well as between correlation predictions and experimental results. In this respect, four well-known void fraction correlations are compared against each other and with experimental results obtained in the Brown University Two-Phase Flow Research Facility.

  8. Simulation of interdiffusion and voids growth based on cellular automata

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Zhang, Boyan; Zhang, Nan; Du, Haishun; Zhang, Xinhong

    2017-02-01

    In the interdiffusion of two solid-state materials, if the diffusion coefficients of the two materials are not the same, the interface of the two materials will shift to the material with the lower diffusion coefficient. This effect is known as the Kirkendall effect. The Kirkendall effect leads to Kirkendall porosity. The pores act as sinks for vacancies and become voids. In this paper, the movement of the Kirkendall plane at interdiffusion is simulated based on cellular automata. The number of vacancies, the critical radius of voids nucleation and the nucleation rate are analysed. The vacancies diffusion, vacancies aggregation and voids growth are also simulated based on cellular automata.

  9. Sacral Nerve Stimulation for the Management of Voiding Dysfunction

    PubMed Central

    Das, Anurag K; White, Mark D; Longhurst, Penelope A

    2000-01-01

    Voiding dysfunction is common, and patients with urge incontinence, frequency/urgency syndromes, and chronic urinary retention are challenging to treat once conservative therapies (such as pharmacologic agents, pelvic floor rehabilitation, and intermittent catheterization) have been exhausted. Sacral nerve stimulation (SNS) is a new, minimally invasive, reversible therapy for the management of refractory voiding dysfunction and provides an attractive therapeutic alternative for patients with this condition. In this review, the role of SNS in the management of voiding dysfunction is examined critically, and the efficacy, risks, and benefits of this new modality are evaluated. PMID:16985735

  10. The effect of crumb rubber particle size to the optimum binder content for open graded friction course.

    PubMed

    Ibrahim, Mohd Rasdan; Katman, Herda Yati; Karim, Mohamed Rehan; Koting, Suhana; Mashaan, Nuha S

    2014-01-01

    The main objective of this paper is to investigate the relations of rubber size, rubber content, and binder content in determination of optimum binder content for open graded friction course (OGFC). Mix gradation type B as specified in Specification for Porous Asphalt produced by the Road Engineering Association of Malaysia (REAM) was used in this study. Marshall specimens were prepared with four different sizes of rubber, namely, 20 mesh size [0.841 mm], 40 mesh [0.42 mm], 80 mesh [0.177 mm], and 100 mesh [0.149 mm] with different concentrations of rubberised bitumen (4%, 8%, and 12%) and different percentages of binder content (4%-7%). The appropriate optimum binder content is then selected according to the results of the air voids, binder draindown, and abrasion loss test. Test results found that crumb rubber particle size can affect the optimum binder content for OGFC.

  11. Assessment of voiding function in inhabitants infected with Schistosoma haematobium.

    PubMed

    Watanabe, Kanji; Muhoho, Ngethe D; Mutua, Wilfred R; Kiliku, Francis M; Awazawa, Toshiki; Moji, Kazuhiko; Aoki, Yoshiki

    2011-08-01

    Voiding function of Schistosoma haematobium infected students was evaluated in 45 schoolboys in Kwale district, Coast province, Kenya, using a questionnaire and uroflowmetry. Sixty-eight schoolboys who were S. haematobium negative were also examined. Symptoms related to the lower urinary tract were qualitatively assessed using the International Prostate Symptoms Score (I-PSS) questionnaire. The I-PSS showed that S. haematobium infected boys felt the need to strain to urinate and post voiding some urine still remained. To examine the disturbances revealed by I-PSS quantitatively, voiding was assessed by a portable uroflowmeter and a bladder scanner. Unexpectedly, no significant residual urine post voiding and no decline in urine flow rates were found in S. haematobium infected boys. However, volume-corrected maximum and average flow rates in S. haematobium infected boys were higher than in those not infected. These results suggest that cystitis associated with S. haematobium infection causes irritation and hypercontraction of the bladder.

  12. Void control in the crystallization of lithium fluoride

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Perry, William D.

    1991-01-01

    The effect of tungsten-coated graphite fibers on the radiant heat transfer characteristics of salt-fiber composites was studied by measuring the onset of melting as a function of applied furnace power. As the fiber concentration was increased from 0 to 5.40 percent fiber by weight, the furnace temperature required to melt the lithium fluoride also increased. Upon cooling, each of the crystalline salt-fiber composites were cut open with a diamond saw to expose the void. Optical photographs of the voids revealed a trend in void location and size, with the largest void, and the least change in the outer dimension of the boule upon cooling, occurring in the sample with the most fiber.

  13. Influence of voids on the strength of wrought materials

    NASA Technical Reports Server (NTRS)

    Shaw, M. C.; Pai, D. M.

    1985-01-01

    Three-dimensional voids, which are present in most materials, may be satisfactorily modelled by two-dimensional holes (i.e., cylindrical voids) in sheet metal. In this study, the influence of certain orientations and shapes of voids upon the mechanical properties and fracture behavior of certain ductile materials has been studied. The presence of voids is found to exert a negligible influence on the ultimate tensile strength, owing to plastic flow neutralizing the stress intensification present before yielding occurs. The shape and orientation of the defects, however, are seen to play an important role relative to strain at fracture. The maximum intensified tensile stress criterion which holds for brittle materials is found to apply to ductile materials as well.

  14. Influence of dust void on neon DC discharge

    NASA Astrophysics Data System (ADS)

    Shumova, V. V.; Polyakov, D. N.; Vasilyak, L. M.

    2017-03-01

    The diffusion/drift model of the positive column of glow discharge in neon with fine dust particles was used to study the role of a dust cloud with a void in the interaction between plasma and dust particles in the range of neon pressure and discharge current where dust particles may form structures with cavities. The results represent the nonlocal effect of void size on plasma composition, configuration of electric field and on distributions of plasma components in discharge with voids in dust structures. Simulations show that the electric field strength and the metastable atom concentration inside the void are higher than in the discharge without dust particles, while electron concentration may be either higher or lower.

  15. Evolution of shock through a void in foam

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Smidt, J. M.; Murphy, T. J.; Douglass, M. R.; Devolder, B. G.; Fincke, J. R.; Schmidt, D. W.; Cardenas, T.; Newman, S. G.; Hamilton, C. E.; Sedillo, T. J.; Los Alamos, NM 87544 Team

    2016-10-01

    Marble implosion is an experimental campaign intended to study the effects of heterogeneous mix on fusion burn. A spherical capsule is composed of deuterated plastic foam of controlled pore (or void) size with tritium fill in pores. As capsule implosion evolves, the initially separated deuterium and tritium will mix, producing DT yields. Void evolution during implosion is of interest for the Marble campaign. A shock tube, driven by the laser at Omega, was designed to study the evolution of a shock through a foam-filled ``void'' and subsequent void evolution. Targets were comprised of a 100 mg/cc CH foam tube containing a 200-µm diameter, lower density doped foam sphere. High-quality, radiographic images were obtained from both 2% iodine-doped in plastic foam and 15% tin-doped in aerogel foam. These experiments will be used to inform simulations.

  16. Void Points, Rosettes, and a Brief History of Planetary Astronomy

    NASA Astrophysics Data System (ADS)

    Kosso, Peter

    2013-12-01

    Almost all models of planetary orbits, from Aristotle through Newton, include void points, empty points in space that have an essential role in defining the orbit. By highlighting the role of these void points, as well as the rosette pattern of the orbit that often results, I bring out different features in the history of planetary astronomy and place a different emphasis on its revolutionary changes, different from those rendered in terms of epicycles or the location of the earth.

  17. Excursion sets and non-Gaussian void statistics

    SciTech Connect

    D'Amico, Guido; Musso, Marcello; Paranjape, Aseem; Norena, Jorge

    2011-01-15

    Primordial non-Gaussianity (NG) affects the large scale structure (LSS) of the Universe by leaving an imprint on the distribution of matter at late times. Much attention has been focused on using the distribution of collapsed objects (i.e. dark matter halos and the galaxies and galaxy clusters that reside in them) to probe primordial NG. An equally interesting and complementary probe however is the abundance of extended underdense regions or voids in the LSS. The calculation of the abundance of voids using the excursion set formalism in the presence of primordial NG is subject to the same technical issues as the one for halos, which were discussed e.g. in Ref. [51][G. D'Amico, M. Musso, J. Norena, and A. Paranjape, arXiv:1005.1203.]. However, unlike the excursion set problem for halos which involved random walks in the presence of one barrier {delta}{sub c}, the void excursion set problem involves two barriers {delta}{sub v} and {delta}{sub c}. This leads to a new complication introduced by what is called the 'void-in-cloud' effect discussed in the literature, which is unique to the case of voids. We explore a path integral approach which allows us to carefully account for all these issues, leading to a rigorous derivation of the effects of primordial NG on void abundances. The void-in-cloud issue, in particular, makes the calculation conceptually rather different from the one for halos. However, we show that its final effect can be described by a simple yet accurate approximation. Our final void abundance function is valid on larger scales than the expressions of other authors, while being broadly in agreement with those expressions on smaller scales.

  18. In-situ oil shale retort with differing upper and lower void fractions

    SciTech Connect

    Ricketts, T.E.

    1984-03-06

    An in situ oil shale retort is formed in a subterranean formation by excavating voids adjacent the top and bottom boundaries of the retort, leaving an intermediate zone of unfragmented formation between the voids. The lower level void is substantially larger than the upper level void. A lower portion of the intermediate zone is explosively expanded downwardly towards the lower level void for forming a first moiety of a fragmented mass of formation particles in the retort and leaving a void space over the top of the first moiety having about the same volume as the upper level void. Thereafter an upper portion of the intermediate zone is explosively expanded upwardly towards the upper level void and downwardly towards the void space for forming a second moiety of the fragmented mass in the retort. The fragmented mass has an average void fraction up to about 25% and no substantial part has a void fraction less than about 20%.

  19. Weak lensing by voids in modified lensing potentials

    SciTech Connect

    Barreira, Alexandre; Cautun, Marius; Li, Baojiu; Baugh, Carlton M.; Pascoli, Silvia E-mail: m.c.cautun@durham.ac.uk E-mail: c.m.baugh@durham.ac.uk

    2015-08-01

    We study lensing by voids in Cubic Galileon and Nonlocal gravity cosmologies, which are examples of theories of gravity that modify the lensing potential. We find voids in the dark matter and halo density fields of N-body simulations and compute their lensing signal analytically from the void density profiles, which we show are well fit by a simple analytical formula. In the Cubic Galileon model, the modifications to gravity inside voids are not screened and they approximately double the size of the lensing effects compared to GR. The difference is largely determined by the direct effects of the fifth force on lensing and less so by the modified density profiles. For this model, we also discuss the subtle impact on the force and lensing calculations caused by the screening effects of haloes that exist in and around voids. In the Nonlocal model, the impact of the modified density profiles and the direct modifications to lensing are comparable, but they boost the lensing signal by only ≈ 10%, compared with that of GR. Overall, our results suggest that lensing by voids is a promising tool to test models of gravity that modify lensing.

  20. A Least-Squares Transport Equation Compatible with Voids

    SciTech Connect

    Hansen, Jon; Peterson, Jacob; Morel, Jim; Ragusa, Jean; Wang, Yaqi

    2014-12-01

    Standard second-order self-adjoint forms of the transport equation, such as the even-parity, odd-parity, and self-adjoint angular flux equation, cannot be used in voids. Perhaps more important, they experience numerical convergence difficulties in near-voids. Here we present a new form of a second-order self-adjoint transport equation that has an advantage relative to standard forms in that it can be used in voids or near-voids. Our equation is closely related to the standard least-squares form of the transport equation with both equations being applicable in a void and having a nonconservative analytic form. However, unlike the standard least-squares form of the transport equation, our least-squares equation is compatible with source iteration. It has been found that the standard least-squares form of the transport equation with a linear-continuous finite-element spatial discretization has difficulty in the thick diffusion limit. Here we extensively test the 1D slab-geometry version of our scheme with respect to void solutions, spatial convergence rate, and the intermediate and thick diffusion limits. We also define an effective diffusion synthetic acceleration scheme for our discretization. Our conclusion is that our least-squares Sn formulation represents an excellent alternative to existing second-order Sn transport formulations

  1. Correction for dynamic bias error in transmission measurements of void fraction

    NASA Astrophysics Data System (ADS)

    Andersson, P.; Sundén, E. Andersson; Svärd, S. Jacobsson; Sjöstrand, H.

    2012-12-01

    Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission within the time scale of the measurement implies a bias, which can be difficult to correct for. A typical example is the tomographic or radiographic mapping of void content in dynamic two-phase flow systems. In this work, the dynamic bias error is described and a method to make a first-order correction is derived. A prerequisite for this method is variance estimates of the system dynamics, which can be obtained using high-speed, time-resolved data acquisition. However, in the absence of such acquisition, a priori knowledge might be used to substitute the time resolved data. Using synthetic data, a void fraction measurement case study has been simulated to demonstrate the performance of the suggested method. The transmission length of the radiation in the object under study and the type of fluctuation of the void fraction have been varied. Significant decreases in the dynamic bias error were achieved to the expense of marginal decreases in precision.

  2. Isolation and control of voids and void-hillocks during molecular beam epitaxial growth of HgCdTe

    NASA Astrophysics Data System (ADS)

    Chandra, D.; Aqariden, F.; Frazier, J.; Gutzler, S.; Orent, T.; Shih, H. D.

    2000-06-01

    Formation of small voids and defect complexes involving small voids during the molecular beam epitaxial growth of mercury cadmium telluride on cadmium zinc telluride was investigated. Some of these defects were demonstrated to form away from the substrate-epi interface. Other defects were demonstrated to close before reaching the top surface without leaving any perturbations on the surface, thus remaining completely hidden. The voids, which formed away from the substrate-epifilm fixed interface, nucleated on defects introduced into the film already grown, leading to the formation of defect complexes, unlike the voids which nucleated at the substrate-epifilm fixed interface. These defect complexes are decorated with high density dislocation nests. The voids which closed before reaching the film surface usually also nucleated slightly away from the film-substrate interface, continued to replicate for a while as the growth progressed, but then relatively rapidly closed off at a significant depth from the film surface. These voids also appeared to form defect complexes with other kinds of defects. Correlations between these materials defects and performance of individual vertically integrated photodiode (VIP) devices were demonstrated, where the relative location of these defects with respect to the junction boundary appears to be particularly important. Elimination or reduction of fluctuations in relative flux magnitudes or substrate temperature, more likely during multi-composition layer growth, yielded films with significantly lower defect concentrations.

  3. Void probability as a function of the void's shape and scale-invariant models

    NASA Technical Reports Server (NTRS)

    Elizalde, E.; Gaztanaga, E.

    1991-01-01

    The dependence of counts in cells on the shape of the cell for the large scale galaxy distribution is studied. A very concrete prediction can be done concerning the void distribution for scale invariant models. The prediction is tested on a sample of the CfA catalog, and good agreement is found. It is observed that the probability of a cell to be occupied is bigger for some elongated cells. A phenomenological scale invariant model for the observed distribution of the counts in cells, an extension of the negative binomial distribution, is presented in order to illustrate how this dependence can be quantitatively determined. An original, intuitive derivation of this model is presented.

  4. Evaluation of elemental content in air-borne particulate matter in low-level atmosphere of Bratislava

    NASA Astrophysics Data System (ADS)

    Merešová, J.; Florek, M.; Holý, K.; Ješkovský, M.; Sýkora, I.; Frontasyeva, M. V.; Pavlov, S. S.; Bujdoš, M.

    A one-year study on total air-borne particulate matter has been undertaken in the framework of air pollution project in Bratislava. The 16 filter samples were collected in 2004 in order to evaluate the level of pollution and assess the potential environmental hazards in Bratislava. As a result of two irradiations with neutrons and four gamma-spectrometric measurements the concentrations of 30 chemical elements (Na, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Ga, As, Se, Br, Rb, In, Sb, I, Cs, Ba, La, Sm, Dy, Tm, W, Au, Hg, Th, U) were determined using instrumental neutron activation analysis (INAA). Additionally the concentrations of other six elements (Cr, Ni, Cu, Zn, Cd, Pb) were measured by atomic absorption spectrometry (AAS). The comparison with other European cities was carried out. Crustal enrichment factors were calculated in order to distinguish the possible sources of air-borne particulate matter. For some elements elevated concentrations were observed for the summer months. The other concentrations were relatively stable over the year.

  5. 21 CFR 888.3045 - Resorbable calcium salt bone void filler device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Resorbable calcium salt bone void filler device... salt bone void filler device. (a) Identification. A resorbable calcium salt bone void filler device is... entitled “Class II Special Controls Guidance: Resorbable Calcium Salt Bone Void Filler Device; Guidance...

  6. 21 CFR 888.3045 - Resorbable calcium salt bone void filler device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Resorbable calcium salt bone void filler device... salt bone void filler device. (a) Identification. A resorbable calcium salt bone void filler device is... entitled “Class II Special Controls Guidance: Resorbable Calcium Salt Bone Void Filler Device; Guidance...

  7. 21 CFR 888.3045 - Resorbable calcium salt bone void filler device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Resorbable calcium salt bone void filler device... salt bone void filler device. (a) Identification. A resorbable calcium salt bone void filler device is... entitled “Class II Special Controls Guidance: Resorbable Calcium Salt Bone Void Filler Device; Guidance...

  8. 21 CFR 888.3045 - Resorbable calcium salt bone void filler device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Resorbable calcium salt bone void filler device... salt bone void filler device. (a) Identification. A resorbable calcium salt bone void filler device is... entitled “Class II Special Controls Guidance: Resorbable Calcium Salt Bone Void Filler Device; Guidance...

  9. 21 CFR 888.3045 - Resorbable calcium salt bone void filler device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Resorbable calcium salt bone void filler device... salt bone void filler device. (a) Identification. A resorbable calcium salt bone void filler device is... entitled “Class II Special Controls Guidance: Resorbable Calcium Salt Bone Void Filler Device; Guidance...

  10. Elastic wave propagation through a material with voids

    NASA Astrophysics Data System (ADS)

    Wright, Thomas W.

    1998-10-01

    An exact mathematical analogy exists between plane wave propagation through a material with voids and axial wave propagation along a circular cylindrical rod with radial shear and inertia. In both cases the internal energy can be regarded as a function of a displacement gradient, an internal variable, and the gradient of the internal variable. In the rod the internal variable represents radial strain, and in the material with voids it is related to changes in void volume fraction. In both cases kinetic energy is associated not only with particle translation, but also with the internal variable. In the rod this microkinetic energy represents radial inertia ; in the material with voids it represents dilitational inertia around the voids. Thus, the basis for the analogy is that in both cases there are two kinematic degrees of freedom, the Lagrangians are identical in form, and therefore, the Euler-Lagrange equations are also identical in form. Of course, the constitutive details and the internal length scales for the two cases are very different, but insight into the behavior of rods can be transferred directly to interpreting the effects of wave propagation in a material with voids. The main result is that just as impact on the end of a rod produces a pulse that first travels with the longitudinal wave speed and then transfers the bulk of its energy into a dispersive wave that travels with the bar speed (calculated using Youngs modulus), so impact on the material with voids produces a pulse that also begins with the longitudinal speed but then transfers to a slower dispersive wave whose speed is determined by an effective longitudinal modulus. The rate of transfer and the strength of the dispersive effect depend on the details in the two cases.

  11. Void Management in MEPHISTO and Other Space Experiments

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Johnston, J. Christopher; Wei, Bingbo

    1998-01-01

    The second flight of NASA's Shuttle Flight experiment program known as MEPHISTO suffered from a void in the liquid portion of the sample, even though a piston arrangement was in place to keep the ampoule filled. In preparations for the next flight of the MEPHISTO furnace an animated computer program, called MEPHISTO Volume Visualizer (MVV), was written to help avoid the formation of unwanted voids. A piston system on MEPHISTO has the ability to move approximately 5 mm in compression, to accommodate expansion of the solid during heating; then from the completely compressed position, the piston can move up to 25 mm in towards the sample, effectively making the ampoule smaller and hopefully eliminating any voids. Due to the nature of the piston design and ampoule and sample arrangement, the piston has gotten stuck during normal directional solidification; this creates the risk of a void. To eliminate such a void, the liquid in the hot zones of the furnace can be heated, thereby expanding the liquid and consuming any void. The problem with this approach is that if the liquid is heated too much an overpressure could result, breaking the ampoule and ending the experiment catastrophically. The MVV has been found to be a useful tool in the assessment of the risks associated with the formation of a void and the additional heating of the liquid in the hot zone of this Bridgman type furnace. The MVV software will be discussed and copies available; it is written in the Delphi 2 programming language and runs under Windows 95 and NT. The strategies used in other flight experiments, such as the Isothermal Dendritic Growth Experiment, will also be presented.

  12. A Content Analysis Comparing Gender Images in Network Television Commercials Aired in Daytime, Evening, and Weekend Telecasts.

    ERIC Educational Resources Information Center

    Craig, R. Stephen

    A content analysis comparing gender portrayals in 2,209 network television commercials was conducted. Many earlier studies treated television advertising's portrayal of men as unproblematic and excluded ads aimed specifically at men from the study sample. To address this shortcoming, the sample was chosen from three different day parts: (1)…

  13. Soil carbon isotopic composition and soil carbon content in an agroecosystem during six years of Free Air Carbon dioxide Enrichment (FACE).

    PubMed

    Giesemann, Anette; Weigel, Hans-Joachim

    2008-12-01

    The Free Air Carbon dioxide Enrichment (FACE) experiment conducted at the Federal Agricultural Research Centre (FAL) in Braunschweig in an arable crop rotation (total duration six years) allowed us to trace carbon (C) input in the soil C pool, as the CO(2), used in the experiment to increase the atmospheric CO(2) concentration, was depleted in (13)C. Accurate assessment of the C input by means of stable C isotope analysis requires detailed knowledge on the spatial distribution of both the C isotopic composition and the C content in the soil C. Assumed changes in these parameters were examined. CO(2) enrichment treatment over a six year period resulted in a clear trend towards an increase of soil C content in the uppermost 10 cm of soil. About 4.9% of the soil C present under ambient air conditions, and 10.7% present under elevated CO(2) conditions were determined as new input. However, the results are not statistically significant yet.

  14. Autonomous robot for detecting subsurface voids and tunnels using microgravity

    NASA Astrophysics Data System (ADS)

    Wilson, Stacy S.; Crawford, Nicholas C.; Croft, Leigh Ann; Howard, Michael; Miller, Stephen; Rippy, Thomas

    2006-05-01

    Tunnels have been used to evade security of defensive positions both during times of war and peace for hundreds of years. Tunnels are presently being built under the Mexican Border by drug smugglers and possibly terrorists. Several have been discovered at the border crossing at Nogales near Tucson, Arizona, along with others at other border towns. During this war on terror, tunnels under the Mexican Border pose a significant threat for the security of the United States. It is also possible that terrorists will attempt to tunnel under strategic buildings and possibly discharge explosives. The Center for Cave and Karst Study (CCKS) at Western Kentucky University has a long and successful history of determining the location of caves and subsurface voids using microgravity technology. Currently, the CCKS is developing a remotely controlled robot which will be used to locate voids underground. The robot will be a remotely controlled vehicle that will use microgravity and GPS to accurately detect and measure voids below the surface. It is hoped that this robot will also be used in military applications to locate other types of voids underground such as tunnels and bunkers. It is anticipated that the robot will be able to function up to a mile from the operator. This paper will describe the construction of the robot and the use of microgravity technology to locate subsurface voids with the robot.

  15. An analytical model for porous single crystals with ellipsoidal voids

    NASA Astrophysics Data System (ADS)

    Mbiakop, A.; Constantinescu, A.; Danas, K.

    2015-11-01

    A rate-(in)dependent constitutive model for porous single crystals with arbitrary crystal anisotropy (e.g., FCC, BCC, HCP, etc.) containing general ellipsoidal voids is developed. The proposed model, denoted as modified variational model (MVAR), is based on the nonlinear variational homogenization method, which makes use of a linear comparison porous material to estimate the response of the nonlinear porous single crystal. Periodic multi-void finite element simulations are used in order to validate the MVAR for a large number of parameters including cubic (FCC, BCC) and hexagonal (HCP) crystal anisotropy, various creep exponents (i.e., nonlinearity), several stress triaxiality ratios, general void shapes and orientations and various porosity levels. The MVAR model, which involves a priori no calibration parameters, is found to be in good agreement with the finite element results for all cases considered in the rate-dependent context. The model is then used in a predictive manner to investigate the complex response of porous single crystals in several cases with strong coupling between the anisotropy of the crystal and the (morphological) anisotropy induced by the shape and orientation of the voids. Finally, a simple way of calibrating the MVAR with just two adjustable parameters is depicted in the rate-independent context so that an excellent agreement with the FE simulation results is obtained. In this last case, this proposed model can be thought as a generalization of the Gurson model in the context of porous single crystals and general ellipsoidal void shapes and orientations.

  16. The Star Formation Properties of Void Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Moorman, Crystal; Vogeley, Michael S.

    2016-01-01

    We measure the star formation properties of two large samples of galaxies from the SDSS in large-scale cosmic voids on time scales of 10 Myr and 100 Myr, using Ha emission line strengths and GALEX FUV fluxes, respectively. The first sample consists of 109,818 optically selected galaxies. We find that void galaxies in this sample have higher specific star formation rates (SSFRs; star formation rates per unit stellar mass) than similar stellar mass galaxies in denser regions. The second sample is a subset of the optically selected sample containing 8070 galaxies with reliable S/N HI detections from ALFALFA. For the HI detected sample, SSFRs are similar regardless of large-scale environment. Investigating only the HI detected dwarf galaxies reveals a trend towards higher SSFRs in voids. Furthermore, we estimate the star formation rate per unit HI mass, known as the star formation efficiency (SFE) of a galaxy, as a function of environment. For the overall HI detected population, we notice no environmental dependence. Limiting the sample to dwarf galaxies again reveals a trend towards higher SFEs in voids. These results suggest that void environments provide a nurturing environment for dwarf galaxy evolution.

  17. On the Star Formation Properties of Void Galaxies

    NASA Astrophysics Data System (ADS)

    Moorman, Crystal M.; Moreno, Jackeline; White, Amanda; Vogeley, Michael S.; Hoyle, Fiona; Giovanelli, Riccardo; Haynes, Martha P.

    2016-11-01

    We measure the star formation properties of two large samples of galaxies from the SDSS in large-scale cosmic voids on timescales of 10 and 100 Myr, using Hα emission line strengths and GALEX FUV fluxes, respectively. The first sample consists of 109,818 optically selected galaxies. We find that void galaxies in this sample have higher specific star formation rates (SSFRs; star formation rates per unit stellar mass) than similar stellar mass galaxies in denser regions. The second sample is a subset of the optically selected sample containing 8070 galaxies with reliable H i detections from ALFALFA. For the full H i detected sample, SSFRs do not vary systematically with large-scale environment. However, investigating only the H i detected dwarf galaxies reveals a trend toward higher SSFRs in voids. Furthermore, we estimate the star formation rate per unit H i mass (known as the star formation efficiency; SFE) of a galaxy, as a function of environment. For the overall H i detected population, we notice no environmental dependence. Limiting the sample to dwarf galaxies still does not reveal a statistically significant difference between SFEs in voids versus walls. These results suggest that void environments, on average, provide a nurturing environment for dwarf galaxy evolution allowing for higher specific star formation rates while forming stars with similar efficiencies to those in walls.

  18. Late Quaternary continental and marine sediments of northeastern Buenos Aires province (Argentina): Fossil content and paleoenvironmental interpretation

    NASA Astrophysics Data System (ADS)

    Fucks, Enrique; Aguirre, Marina; Deschamps, Cecilia M.

    2005-10-01

    Abundant invertebrate and vertebrate fossil remains that exhibit excellent preservation and were collected from deposits of both continental and marine origins at Pilar (Buenos Aires, Argentina) add paleoenvironmental data from the northeastern Buenos Aires province area linked to sea-level oscillations and climate variability since approximately 120 ka BP (marine oxygen isotope stage [MOIS] 5e). Two new fossiliferous localities discovered in the Luján River Valley allow for detailed geological studies and new dating of molluscan shells and bones. The studies suggest salinity changes during the Last Interglacial (8 m above m.s.l., min. 14C>40 ka) and the mid-Holocene transgression (5 m above m.s.l., 7-3 14C ka BP) compared with the modern pattern along the adjacent littoral (Río de la Plata). The marine sequences represent the innermost boundary of the sea-level transgression in that area and contain a biogenic record (bivalves, gastropods, forams, ostracods) that indicates marginal marine environments (higher salinity than at present). Vertebrates and molluscs from the continental sequence suggest a freshwater habitat in which remains of marine fish must be allochthonous, probably incorporated by postmortem fluvial transport to the final depositional environment.

  19. Quantifying Void Ratio Variation in Sand using Computed Tomography

    NASA Technical Reports Server (NTRS)

    Alshibli, Khalid A.; Batiste, Susan N.; Swanson, Roy A.; Sture, Stein; Costes, Nicholas C.; Lankton, Mark R.

    1999-01-01

    A series of displacement-controlled, conventional, drained axisymmetric (triaxial) experiments were conducted on dry Ottawa sand specimens at very low effective confining stresses in a microgravity environment aboard the Space Shuttle during the NASA STS-89 mission. Post-flight analysis included studying the internal fabric and failure patterns of these specimens using Computed Tomography (CT). The CT scans of three specimens subjected to different compression levels (uncompressed specimen, a specimen compressed to 3.3% nominal axial strain (epsilon(sub a)), and a specimen compressed to 25% epsilon(sub a)) are presented to investigate the evolution of instability patterns and to quantify void ratio variation. The progress of failure is described and discussed. Also, specimens' densities were calibrated using standard ASTM procedures and void ratio spatial variation was calculated and represented by contour maps and histograms. The CT technique demonstrated good ability to detect specimen inhomogeneities, localization patterns, and quantifying void ratio variation within sand specimens.

  20. Voids as a precision probe of dark energy

    SciTech Connect

    Biswas, Rahul; Alizadeh, Esfandiar; Wandelt, Benjamin D.

    2010-07-15

    The shapes of cosmic voids, as measured in spectroscopic galaxy redshift surveys, constitute a promising new probe of dark energy (DE). We forecast constraints on the DE equation of state and its variation from current and future surveys and find that the promise of void shape measurements compares favorably to that of standard methods such as supernovae and cluster counts even for currently available data. Owing to the complementary nature of the constraints, void shape measurements improve the Dark Energy Task Force figure of merit by 2 orders of magnitude for a future large scale experiment such as EUCLID when combined with other probes of dark energy available on a similar time scale. Modeling several observational and theoretical systematics has only moderate effects on these forecasts. We discuss additional systematics which will require further study using simulations.

  1. Tunnel and Subsurface Void Detection and Range to Target Measurement

    SciTech Connect

    Phillip B. West

    2009-06-01

    Engineers and technicians at the Idaho National Laboratory invented, designed, built and tested a device capable of detecting and measuring the distance to, an underground void, or tunnel. Preliminary tests demonstrated positive detection of, and range to, a void thru as much as 30 meters of top-soil earth. Device uses acoustic driving point impedance principles pioneered by the Laboratory for well-bore physical properties logging. Data receipts recorded by the device indicates constructive-destructive interference patterns characteristic of acoustic wave reflection from a downward step-change in impedance mismatch. Prototype tests demonstrated that interference patterns in receipt waves could depict the patterns indicative of specific distances. A tool with this capability can quickly (in seconds) indicate the presence and depth/distance of a void or tunnel. Using such a device, border security and military personnel can identify threats of intrusion or weapons caches in most all soil conditions including moist and rocky.

  2. Pressurized water reactor fuel assembly subchannel void fraction measurement

    SciTech Connect

    Akiyama, Yoshiei; Hori, Keiichi; Miyazaki, Keiji; Mishima, Kaichiro; Sugiyama, Shigekazu

    1995-12-01

    The void fraction measurement experiment of pressurized water reactor (PWR) fuel assemblies has been conducted since 1987 under the sponsorship of the Ministry of International Trade and Industry as a Japanese national project. Two types of test sections are used in this experiment. One is a 5 x 5 array rod bundle geometry, and the other is a single-channel geometry simulating one of the subchannels in the rod bundle. Wide gamma-ray beam scanners and narrow gamma-ray beam computed tomography scanners are used to measure the subchannel void fractions under various steady-state and transient conditions. The experimental data are expected to be used to develop a void fraction prediction model relevant to PWR fuel assemblies and also to verify or improve the subchannel analysis method. The first series of experiments was conducted in 1992, and a preliminary evaluation of the data has been performed. The preliminary results of these experiments are described.

  3. Testing cosmic geometry without dynamic distortions using voids

    SciTech Connect

    Hamaus, Nico; Sutter, P.M.; Lavaux, Guilhem; Wandelt, Benjamin D. E-mail: sutter@iap.fr E-mail: wandelt@iap.fr

    2014-12-01

    We propose a novel technique to probe the expansion history of the Universe based on the clustering statistics of cosmic voids. In particular, we compute their two-point statistics in redshift space on the basis of realistic mock galaxy catalogs and apply the Alcock-Paczynski test. In contrast to galaxies, we find void auto-correlations to be marginally affected by peculiar motions, providing a model-independent measure of cosmological parameters without systematics from redshift-space distortions. Because only galaxy-galaxy and void-galaxy correlations have been considered in these types of studies before, the presented method improves both statistical and systematic uncertainties on the product of angular diameter distance and Hubble rate, furnishing the potentially cleanest probe of cosmic geometry available to date.

  4. Void nucleation and disentanglement in glassy amorphous polymers

    NASA Astrophysics Data System (ADS)

    Mahajan, Dhiraj K.; Singh, Bhupinder; Basu, Sumit

    2010-07-01

    Cavitation in glassy polymers is known to result from highly triaxial states of local stress and the presence of impurities. Understanding of cavitation, particularly void nucleation, is important as cavities are precursors to crazes, which in turn lead to fracture. In this work we study the early stages of void nucleation in glassy amorphous polymers by imposing, in well designed molecular dynamics simulations, highly triaxial states of stress on ensembles of entangled linear macromolecular chains and monitoring the evolution of the entanglement network. Our results demonstrate that deformation induced disentanglement and rearrangement of topological constraints along individual chains play an important role in the early stages of void nucleation. Even in the glassy state, deformation causes significant changes in the rheological constraints on a chain though the number of interchain binary contacts may not change much.

  5. Viscoplastic selfconsistent modelling of the anisotropic behavior of voided polycrystals

    SciTech Connect

    Lebensohn, R. A.; Maudlin, P. J.; Tomé, C. N. ,

    2004-01-01

    In this work we consider the presence of ellipsoidal voids inside polycrystals submitted to large strain deformation. For this purpose, the originally incompressible viscoplastic selfconsistent (VPSC) formulation has been extended to deal with compressible polyaystals. Such an extended model allows us to account for porosity evolution in voided polycrystals, while preserving the anisotropy and crystallographic capabilities of the VPSC formulation. We present several applications of this extended VPSC model, which address the coupling between texture, plastic anisotropy, void shape, triaxiality, and porosity evolution. We also discuss the implementation of a multiscale calculation using the present compressible VPSC as constitutive routine inside dynamic FEM codes, for the simulation of deformation processes in which both anisotropy and cavitation became relevant aspects of microstructural evolution.

  6. Avoid a Void: The Eradication of Null Dereferencing

    NASA Astrophysics Data System (ADS)

    Meyer, Bertrand; Kogtenkov, Alexander; Stapf, Emmanuel

    All object-oriented programs, but also those in C or Pascal as soon as they use pointers, are subject to the risk of run-time crash due to "null pointer dereferencing". Until recently this was the case even in statically typed languages. Tony Hoare has called this problem his "billion-dollar mistake". In the type system of ISO-standard Eiffel, the risk no longer exists: void safety (the absence of null pointer dereferencing) has become a property guaranteed by the type system and enforced by the compiler. The mechanism is fully implemented and major libraries and applications have been made void-safe. This presentation describes the principles of Eiffel's void safety, their implementation and the lessons gained.

  7. Study of void sizes and loading configurations effects on shock initiation due to void collapse in heterogeneous energetic materials

    NASA Astrophysics Data System (ADS)

    Roy, Sidhartha; Rai, Nirmal; Udaykumar, H. S.

    2015-06-01

    In heterogeneous energetic materials, presence of porosity has been seen to increase its sensitivity towards shock initiation and ignition. Under the application of shock load, the viscoplastic deformation of voids and its collapse leads to the formation of local high temperature regions known as hot spots. The chemical reaction triggers at the hot spot depending on the local temperature and grows eventually leading to ignition and formation of detonation waves in the material. The temperature of the hot spot depends on various factors such as shock strength, void size, void arrangements, loading configuration etc. Hence, to gain deeper understanding on shock initiation and ignition study due to void collapse, a parametric study involving various factors which can affect the hot spot temperature is desired. In the current work, effects of void sizes, shock strength and loading configurations has been studied for shock initiation in HMX using massively parallel Eulerian code, SCIMITAR3D. The chemical reaction and decomposition for HMX has been modeled using Henson-Smilowitz multi step mechanism. The effect of heat conduction has also been taken into consideration. Ignition threshold criterion has been established for various factors as mentioned. The critical hot spot temperature and its size which can lead to ignition has been obtained from numerical experiments.

  8. Voiding trial outcome following pelvic floor repair without incontinence procedures

    PubMed Central

    Wang, Rui; Won, Sara; Haviland, Miriam J.; Bargen, Emily Von; Hacker, Michele R.; Li, Janet

    2016-01-01

    Introduction and hypothesis Our aim was to identify predictors of postoperative voiding trial failure among patients who had a pelvic floor repair without a concurrent incontinence procedure in order to identify low-risk patients in whom postoperative voiding trials may be modified. Methods We conducted a retrospective cohort study of women who underwent pelvic floor repair without concurrent incontinence procedures at two institutions from 1 November 2011 through 13 October 2013 after abstracting demographic and clinical data from medical records. The primary outcome was postoperative retrograde voiding trial failure. We used modified Poisson regression to calculate the risk ratio (RR) and 95 % confidence interval (CI). Results Of the 371 women who met eligibility criteria, 294 (79.2 %) had complete data on the variables of interest. Forty nine (16.7%) failed the trial, and those women were less likely to be white (p = 0.04), more likely to have had an anterior colporrhaphy (p = 0.001), and more likely to have had a preoperative postvoid residual (PVR) ≥150 ml (p = 0.001). After adjusting for race, women were more likely to fail their voiding trial if they had a preoperative PVR of ≥150 ml (RR: 1.9; 95 % CI: 1.1–3.2); institution also was associated with voiding trial failure (RR: 3.0; 95 % CI: 1.6–5.4). Conclusions Among our cohort, postoperative voiding trial failure was associated with a PVR of ≥150 ml and institution at which the surgery was performed. PMID:26886553

  9. ONLY THE LONELY: H I IMAGING OF VOID GALAXIES

    SciTech Connect

    Kreckel, K.; Van Gorkom, J. H.; Platen, E.; Van de Weygaert, R.; Van der Hulst, J. M.; Aragon-Calvo, M. A.; Yip, C.-W.; Kovac, K.; Peebles, P. J. E.

    2011-01-15

    Void galaxies, residing within the deepest underdensities of the Cosmic Web, present an ideal population for the study of galaxy formation and evolution in an environment undisturbed by the complex processes modifying galaxies in clusters and groups, as well as provide an observational test for theories of cosmological structure formation. We have completed a pilot survey for the H I imaging aspects of a new Void Galaxy Survey (VGS), imaging 15 void galaxies in H I in local (d < 100 Mpc) voids. H I masses range from 3.5 x 10{sup 8} to 3.8 x 10{sup 9} M{sub sun}, with one nondetection with an upper limit of 2.1 x 10{sup 8} M{sub sun}. Our galaxies were selected using a structural and geometric technique to produce a sample that is purely environmentally selected and uniformly represents the void galaxy population. In addition, we use a powerful new backend of the Westerbork Synthesis Radio Telescope that allows us to probe a large volume around each targeted galaxy, simultaneously providing an environmentally constrained sample of fore- and background control samples of galaxies while still resolving individual galaxy kinematics and detecting faint companions in H I. This small sample makes up a surprisingly interesting collection of perturbed and interacting galaxies, all with small stellar disks. Four galaxies have significantly perturbed H I disks, five have previously unidentified companions at distances ranging from 50 to 200 kpc, two are in interacting systems, and one was found to have a polar H I disk. Our initial findings suggest void galaxies are a gas-rich, dynamic population which present evidence of ongoing gas accretion, major and minor interactions, and filamentary alignment despite the surrounding underdense environment.

  10. Voids and constraints on nonlinear clustering of galaxies

    NASA Technical Reports Server (NTRS)

    Vogeley, Michael S.; Geller, Margaret J.; Park, Changbom; Huchra, John P.

    1994-01-01

    Void statistics of the galaxy distribution in the Center for Astrophysics Redshift Survey provide strong constraints on galaxy clustering in the nonlinear regime, i.e., on scales R equal to or less than 10/h Mpc. Computation of high-order moments of the galaxy distribution requires a sample that (1) densely traces the large-scale structure and (2) covers sufficient volume to obtain good statistics. The CfA redshift survey densely samples structure on scales equal to or less than 10/h Mpc and has sufficient depth and angular coverage to approach a fair sample on these scales. In the nonlinear regime, the void probability function (VPF) for CfA samples exhibits apparent agreement with hierarchical scaling (such scaling implies that the N-point correlation functions for N greater than 2 depend only on pairwise products of the two-point function xi(r)) However, simulations of cosmological models show that this scaling in redshift space does not necessarily imply such scaling in real space, even in the nonlinear regime; peculiar velocities cause distortions which can yield erroneous agreement with hierarchical scaling. The underdensity probability measures the frequency of 'voids' with density rho less than 0.2 -/rho. This statistic reveals a paucity of very bright galaxies (L greater than L asterisk) in the 'voids.' Underdensities are equal to or greater than 2 sigma more frequent in bright galaxy samples than in samples that include fainter galaxies. Comparison of void statistics of CfA samples with simulations of a range of cosmological models favors models with Gaussian primordial fluctuations and Cold Dark Matter (CDM)-like initial power spectra. Biased models tend to produce voids that are too empty. We also compare these data with three specific models of the Cold Dark Matter cosmogony: an unbiased, open universe CDM model (omega = 0.4, h = 0.5) provides a good match to the VPF of the CfA samples. Biasing of the galaxy distribution in the 'standard' CDM model

  11. Dimensionality effects in void-induced explosive sensitivity

    DOE PAGES

    Herring, Stuart Davis; Germann, Timothy Clark; Gronbech-Jensen, Niels

    2016-09-02

    Here, the dimensionality of defects in high explosives controls their heat generation and the expansion of deflagrations from them. We compare the behaviour of spherical voids in three dimensions to that of circular voids in two dimensions. The behaviour is qualitatively similar, but the additional focusing along the extra transverse dimension significantly reduces the piston velocity needed to initiate reactions. However, the reactions do not grow as well in three dimensions, so detonations require larger piston velocities. Pressure exponents are seen to be similar to those for the two-dimensional system.

  12. Quantification of the Void Volume in Single-Crystal Silicon.

    PubMed

    D'Agostino, Giancarlo; Di Luzio, Marco; Mana, Giovanni; Martino, Luca; Oddone, Massimo; Sasso, Carlo Paolo

    2016-12-06

    This paper investigates the use of a method based on Cu decoration and neutron activation to determine the total volume of voids in a silicon single crystal. A measurement protocol was developed and tested in an experiment carried out with a 5 cm(3) volume and 10 g mass high-purity natural silicon sample. The few percent uncertainty reached in the determination of the Cu concentration, at a 10(14) cm(-3) level, makes this method a candidate to set an upper limit to the concentration of the vacancies contributing to the void volume in the enriched silicon material used to determine the Avogadro constant.

  13. Ductile damage modeling based on void coalescence and percolation theories

    SciTech Connect

    Tonks, D.L.; Zurek, A.K.; Thissell, W.R.

    1995-09-01

    A general model for ductile damage in metals is presented. It includes damage induced by shear stress as well as damage caused by volumetric tension. Spallation is included as a special case. Strain induced damage is also treated. Void nucleation and growth are included, and give rise to strain rate effects. Strain rate effects also arise in the model through elastic release wave propagation between damage centers. The underlying physics of the model is the nucleation, growth, and coalescence of voids in a plastically flowing solid. The model is intended for hydrocode based computer simulation. An experimental program is underway to validate the model.

  14. Method of uniform rubblization for limited void volume blasting

    SciTech Connect

    Redpath, B.B.; Ricketts, T.E.

    1982-06-08

    There is provided a method of forming an in situ oil shale retort in a retort site within a subterranean formation containing oil shale. The in situ oil shale retort contains a fragmented permeable mass of formation particles. A first portion of formation is excavated from within the boundaries of the retort being formed to form at least one void. The surface of the formation defining such a void provides at least one free face extending through the formation. The second portion of formation is left within the boundaries of the retort being formed to be explosively expanded toward the void. At least two arrays of explosive charges are formed in the second portion of formation wherein the first array of explosive charges has a first burden distance and the second array of explosive charges has a second burden distance wherein the second burden distance is less than the first burden distance. Explosive is detonated for explosively expanding the second portion of formation toward the void to form a fragmented permeable mass of formation particles containing oil shale in the subterranean formation for forming an in situ oil shale retort.

  15. Liquid crystals detect voids in fiber glass laminates

    NASA Technical Reports Server (NTRS)

    Hollar, W. T.

    1967-01-01

    Liquid crystal solution nondestructively detects voids or poor bond lines in fiber glass laminates. A thin coating of the solution is applied by spray or brush to the test article surface, and when heated indicates the exact location of defects by differences in color.

  16. POLAR DISK GALAXY FOUND IN WALL BETWEEN VOIDS

    SciTech Connect

    Stanonik, K.; Van Gorkom, J. H.; Platen, E.; Van de Weygaert, R.; Van der Hulst, J. M.; Aragon-Calvo, M. A.; Peebles, P. J. E.

    2009-05-01

    We have found an isolated polar disk galaxy in what appears to be a cosmological wall situated between two voids. This void galaxy is unique as its polar disk was discovered serendipitously in an H I survey of SDSS void galaxies, with no optical counterpart to the H I polar disk. Yet the H I mass in the disk is comparable to the stellar mass in the galaxy. This suggests slow accretion of the H I material at a relatively recent time. There is also a hint of a warp in the outer parts of the H I disk. The central, stellar disk appears relatively blue, with faint near-UV emission, and is oriented (roughly) parallel to the surrounding wall, implying gas accretion from the voids. The considerable gas mass and apparent lack of stars in the polar disk, coupled with the general underdensity of the environment, supports recent theories of cold flow accretion as an alternate formation mechanism for polar disk galaxies.

  17. Answers from the Void: VIDE and its Applications

    NASA Astrophysics Data System (ADS)

    Sutter, P. M.; Hamaus, N.; Pisani, A.; Lavaux, G.; Wandelt, B. D.

    2016-10-01

    We discuss various applications ofvide, the Void IDentification and Examination toolkit, anopen-source Python/C++ code for finding cosmic voids in galaxy redshift surveysand $N$-body simulations.Based on a substantially enhanced version of ZOBOV, vide not only finds voids, but alsosummarizes their properties, extracts statisticalinformation, and providesa Python-based platform for more detailed analysis, such asmanipulating void catalogs and particle members, filtering, plotting,computing clustering statistics, stacking, comparing catalogs, andfitting density profiles.vide also provides significant additional functionality forpre-processing inputs: for example, vide can work with volume- ormagnitude-limited galaxy samples with arbitrary survey geometries,or darkmatter particles or halo catalogs in a variety of common formats.It can also randomly subsample inputsand includes a Halo Occupation Distribution model forconstructing mock galaxy populations.vide has been used for a wide variety of applications, fromdiscovering a universal density profile to estimatingprimordial magnetic fields, andis publicly available athttp://bitbucket.org/cosmicvoids/vide\\_publicandhttp://www.cosmicvoids.net.

  18. Long term analysis of the biomass content in the feed of a waste-to-energy plant with oxygen-enriched combustion air.

    PubMed

    Fellner, Johann; Cencic, Oliver; Zellinger, Günter; Rechberger, Helmut

    2011-10-01

    Thermal utilization of municipal solid waste and commercial wastes has become of increasing importance in European waste management. As waste materials are generally composed of fossil and biogenic materials, a part of the energy generated can be considered as renewable and is thus subsidized in some European countries. Analogously, CO(2) emissions of waste incinerators are only partly accounted for in greenhouse gas inventories. A novel approach for determining these fractions is the so-called balance method. In the present study, the implementation of the balance method on a waste-to-energy plant using oxygen-enriched combustion air was investigated. The findings of the 4-year application indicate on the one hand the general applicability and robustness of the method, and on the other hand the importance of reliable monitoring data. In particular, measured volume flows of the flue gas and the oxygen-enriched combustion air as well as corresponding O(2) and CO(2) contents should regularly be validated. The fraction of renewable (biogenic) energy generated throughout the investigated period amounted to between 27 and 66% for weekly averages, thereby denoting the variation in waste composition over time. The average emission factor of the plant was approximately 45 g CO(2) MJ(-1) energy input or 450 g CO(2) kg(-1) waste incinerated. The maximum error of the final result was about 16% (relative error), which was well above the error (<8%) of the balance method for plants with conventional oxygen supply.

  19. An initial assessment of spatial relationships between respiratory cases, soil metal content, air quality and deprivation indicators in Glasgow, Scotland, UK: relevance to the environmental justice agenda.

    PubMed

    Morrison, S; Fordyce, F M; Scott, E Marian

    2014-04-01

    There is growing interest in links between poor health and socio-environmental inequalities (e.g. inferior housing, crime and industrial emissions) under the environmental justice agenda. The current project assessed associations between soil metal content, air pollution (NO2/PM10) and deprivation and health (respiratory case incidence) across Glasgow. This is the first time that both chemical land quality and air pollution have been assessed citywide in the context of deprivation and health for a major UK conurbation. Based on the dataset 'averages' for intermediate geography areas, generalised linear modelling of respiratory cases showed significant associations with overall soil metal concentration (p = 0.0367) and with deprivation (p < 0.0448). Of the individual soil metals, only nickel showed a significant relationship with respiratory cases (p = 0.0056). Whilst these associations could simply represent concordant lower soil metal concentrations and fewer respiratory cases in the rural versus the urban environment, they are interesting given (1) possible contributions from soil to air particulate loading and (2) known associations between airborne metals like nickel and health. This study also demonstrated a statistically significant correlation (-0.213; p < 0.05) between soil metal concentration and deprivation across Glasgow. This highlights the fact that despite numerous regeneration programmes, the legacy of environmental pollution remains in post-industrial areas of Glasgow many decades after heavy industry has declined. Further epidemiological investigations would be required to determine whether there are any causal links between soil quality and population health/well-being. However, the results of this study suggest that poor soil quality warrants greater consideration in future health and socio-environmental inequality assessments.

  20. A constitutive model for elastoplastic solids containing primary and secondary voids

    NASA Astrophysics Data System (ADS)

    Fabrègue, D.; Pardoen, T.

    In many ductile metallic alloys, the damage process controlled by the growth and coalescence of primary voids nucleated on particles with a size varying typically between 1 and 100 μm, is affected by the growth of much smaller secondary voids nucleated on inclusions with a size varying typically between 0.1 and 3 μm. The goal of this work is first to quantify the potential effect of the growth of these secondary voids on the coalescence of primary voids using finite element (FE) unit cell calculations and second to formulate a new constitutive model incorporating this effect. The nucleation and growth of secondary voids do essentially not affect the growth of the primary voids but mainly accelerate the void coalescence process. The drop of the ductility caused by the presence of secondary voids increases if the nucleation strain decreases and/or if their volume fraction increases and/or if the primary voids are flat. A strong coupling is indeed observed between the shape of the primary voids and the growth of the second population enhancing the anisotropy of the ductility induced by void shape effects. The new micromechanics-based coalescence condition for internal necking introduces the softening induced by secondary voids growing in the ligament between two primary voids. The FE cell calculations were used to guide and assess the development of this model. The use of the coalescence condition relies on a closed-form model for estimating the evolution of the secondary voids in the vicinity of a primary cavity. This coalescence criterion is connected to an extended Gurson model for the first population including the effect of the void aspect ratio. With respect to classical models for single void population, this new constitutive model improves the predictive potential of damage constitutive models devoted to ductile metal while requiring only two new parameters, i.e. the initial porosity of second population and a void nucleation stress, without any additional

  1. Comparison of voiding cystourethrography and urosonography with second-generation contrast agents in simultaneous prospective study

    PubMed Central

    Świętoń, Dominik; Rybczyńska, Dorota; Czarniak, Piotr; Szarmach, Arkadiusz; Kaszubowski, Mariusz; Szurowska, Edyta

    2016-01-01

    Background The invasiveness and exposure to radiation in voiding cystourethrography led to the introduction of alternative methods of diagnosis of vesicoureteral reflux, including contrast enhanced voiding urosonography. While there is a limited number of studies comparing these methods using new generation ultrasound contrast agents, none of them compared both methods simultaneously. This study is aimed at assessing agreement between contrast enhanced voiding urosonography with second-generation ultrasound contrast agents and voiding cystourethrography. Methods From April 2013 to May 2014, 83 children (37 female and 46 male), mean age 3.5 years, age range from 1 month to 17.5 years, underwent prospective simultaneous assessment by contrast enhanced voiding urosonography and voiding cystourethrography, with a total of 166 uretero-renal units evaluated. Results The sensitivity of voiding cystourethrography and contrast enhanced voiding urosonography were comparable, amounting to 88%, however, neither reached 100% for the entire studied population. The negative predictive value of voiding urosonography and voiding cystourethrography was 97%, and there was no difference between both methods. Conclusion Voiding cystourethrography and contrast enhanced voiding urosonography are comparable methods in diagnosis of vesicoureteral reflux, and can be performed alternatively. However, some limitations of contrast enhanced voiding urosonography must be remembered. PMID:28138405

  2. In Situ Void Fraction and Gas Volume in Hanford Tank 241-SY-101 as Measured with the Void Fraction Instrument

    SciTech Connect

    CW Stewart; G Chen; JM Alzheimer; PA Meyer

    1998-11-10

    The void fraction instrument (WI) was deployed in Tank 241-SY-101 three times in 1998 to confm and locate the retained gas (void) postulated to be causing the accelerating waste level rise observed since 1995. The design, operation, and data reduction model of the WI are described along with validation testing and potential sources of uncertainty. The test plans, field observations and void measurements are described in detail, including the total gas volume calculations and the gas volume model. Based on 1998 data, the void fraction averaged 0.013 i 0.001 in the mixed slurry and 0.30 ~ 0.04 in the crust. This gives gas volumes (at standard pressure and temperature) of 87 t 9 scm in the slurry and 138 ~ 22 scm in the crust for a total retained gas volume of221 *25 scm. This represents an increase of about 74 scm in the crust and a decrease of about 34 scm in the slurry from 1994/95 results. The overall conclusion is that the gas retention is occurring mainly in the crust layer and there is very little gas in the mixed slurry and loosely settled layers below. New insights on crust behavior are also revealed.

  3. Formation of void array inside transparent and absorptive glasses by femtosecond laser irradiation.

    PubMed

    Jang, Wooyoung; Kim, Daejin; Kim, Taehong; Moon, Ayoung; Lim, Ki-Soo; Lee, Myeongkyu; Sohn, Ik-Bu

    2012-06-01

    We demonstrate self-fabrication of void arrays in a fused silica transparent in the visible and a color-filter borosilicate glass strongly absorptive at 800 nm using tightly focused Ti-sapphire femtosecond laser pulses at 1 kHz without scanning. The period, the size, the number of voids, and the length of the aligned void structure were controlled by changing the laser pulse energy, and the position of the focal point inside two materials. The void arrays were observed by an optical microscope and also estimated by an optical diffraction experiment. The void size and period were smaller in the absorptive glass than in the transparent glass. The submicrometer-sized void was observed by a scanning electron microscope. The smaller and clearer void arrays were formed in the color filter than the fused silica glass. With increasing the laser focal depth, the void-array length increased in the fused silica and decreased in the color filter.

  4. Mechanical Stress Effects on Electromigration Voiding in a Meandering Test Stripe

    NASA Technical Reports Server (NTRS)

    Lowry, L. E.; Tai, B. H.; Mattila, J.; Walsh, L. H.

    1993-01-01

    Earlier experimental findings concluded that electromigratin voids in these meandering stripe test structures were not randomly distributed and that void nucleation frequenly occurred sub-surface at the metal/thermal oxide interface.

  5. 40 CFR 1065.526 - Repeating void modes or test intervals.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... that include hybrid energy storage features or emission controls that involve physical or chemical...) If one of the modes of a discrete-mode test is voided as provided in this section, you may void...

  6. 40 CFR 1065.526 - Repeating void modes or test intervals.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... that include hybrid energy storage features or emission controls that involve physical or chemical...) If one of the modes of a discrete-mode test is voided as provided in this section, you may void...

  7. Approximate total Fe content determined by Mössbauer spectrometry: Application to determine the correlation between gamma-ray-emitter activities and total content of Fe phases in soils of the Province of Buenos Aires, Argentina.

    PubMed

    Montes, M L; Rivas, P C; Taylor, M A; Mercader, R C

    2016-10-01

    Pearson correlation coefficients between (40)K, (226)Ra and (232)Th activities and the total Fe phase fractions yielded by Mössbauer spectroscopy have been calculated for soils of the Province of Buenos Aires, Argentina. Total fractions of Fe phases have been obtained from the relative fractions reported in previous works weighted by the Fe soil content and the recoilless-fraction of each Fe phase. An approximate method based on the relationship between the Mössbauer spectral absorption area (obtained from the (57)Fe Mössbauer data) and the total Fe concentration (determined by colorimetric methods, after microwave assisted acid digestion of soil samples) has been used for the first time to determine the Fe concentration in soils with an accuracy of 15%. Protocol to extend the method for unknown samples is also discussed. The determined new coefficients differ from those reported previously. A significant and positive correlation between the total fraction of Fe(2+) and the (40)K activity values has been obtained. This result validates the hypothesis put forward in a previous work, i.e., that illite captures the (40)K existing in the soil. In addition, with the new approximation, the Pearson correlation coefficients for the other natural radionuclides give values that indicate that the methodology reported here is appropriate to study the correlations between the activity values with the total fractions of Fe phases.

  8. Diffusion processes in Al2O3 scales - Void growth, grain growth, and scale growth

    NASA Technical Reports Server (NTRS)

    Smialek, J. L.; Gibala, R.

    1983-01-01

    The internal microstructure and growth kinetics of Al2O3 scales on Ni-15Cr-13Al (wt percent) are investigated by TEM and analyzed in relation to models of diffusivity. Polished arc-melted specimens were oxidized in 1-atm air at 1100 C for 0.1, 1.0, and 20 hours and ion-thinned for TEM at 100 kV. The frequency distribution of void size and grain size is determined for different oxidation times and scale depths. The kinetics of microvoid growth and of grain and scale growth are plotted and related via simplified models to lattice and grain-boundary oxygen diffusivity, respectively. Good agreement is found between model predictions and data obtained by Oishi and Kingery (1960) on oxygen diffusion in bulk Al2O3. The further implications and limitations of these findings are discssed.

  9. Development and assessment of a microwave void-fraction measurement system

    NASA Astrophysics Data System (ADS)

    Pochet, S.; Teyssedou, A.; Akyel, C.

    2014-01-01

    The proof of concept of a non-invasive reflection-type void measurement system using microwaves is developed. Before constructing the instrument, governing equations are used to perform numerical simulations of different electrical components (reflectometer, antenna, etc.). Design and preliminary calibrations are performed based on these simulations. The results are then used to manufacture a setup that is installed on a Plexiglas vertical tube containing known volumetric fractions of gas in water at atmospheric conditions. The amount of injected gas and water are accurately controlled and the response of the system is compared with the simulations which confirm the suitability of such a system to study two-phase water-air mixtures.

  10. Detecting voids in a 0.6 m coal seam, 7 m deep, using seismic reflection

    USGS Publications Warehouse

    Miller, R.D.; Steeples, D.W.

    1991-01-01

    Surface collapse over abandoned subsurface coal mines is a problem in many parts of the world. High-resolution P-wave reflection seismology was successfully used to evaluate the risk of an active sinkhole to a main north-south railroad line in an undermined area of southeastern Kansas, USA. Water-filled cavities responsible for sinkholes in this area are in a 0.6 m thick coal seam, 7 m deep. Dominant reflection frequencies in excess of 200 Hz enabled reflections from the coal seam to be discerned from the direct wave, refractions, air wave, and ground roll on unprocessed field files. Repetitive void sequences within competent coal on three seismic profiles are consistent with the "room and pillar" mining technique practiced in this area near the turn of the century. The seismic survey showed that the apparent active sinkhole was not the result of reactivated subsidence but probably erosion. ?? 1991.

  11. 46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Hold space, void space, cofferdam, and spaces containing... Design, Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam,...

  12. 46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Hold space, void space, cofferdam, and spaces containing... Design, Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam,...

  13. 46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Hold space, void space, cofferdam, and spaces containing... Design, Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam,...

  14. Self-similarity and universality of void density profiles in simulation and SDSS data

    NASA Astrophysics Data System (ADS)

    Nadathur, S.; Hotchkiss, S.; Diego, J. M.; Iliev, I. T.; Gottlöber, S.; Watson, W. A.; Yepes, G.

    2015-06-01

    The stacked density profile of cosmic voids in the galaxy distribution provides an important tool for the use of voids for precision cosmology. We study the density profiles of voids identified using the ZOBOV watershed transform algorithm in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. We compare different methods for reconstructing density profiles scaled by the void radius and show that the most commonly used method based on counts in shells and simple averaging is statistically flawed as it underestimates the density in void interiors. We provide two alternative methods that do not suffer from this effect; one based on Voronoi tessellations is also easily able to account from artefacts due to finite survey boundaries and so is more suitable when comparing simulation data to observation. Using this method, we show that the most robust voids in simulation are exactly self-similar, meaning that their average rescaled profile does not depend on the void size. Within the range of our simulation, we also find no redshift dependence of the mean profile. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The mean profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids.

  15. 46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Hold space, void space, cofferdam, and spaces containing... Design, Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam,...

  16. 46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Hold space, void space, cofferdam, and spaces containing... Design, Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam,...

  17. Energy principles in theory of elastic materials with voids

    NASA Astrophysics Data System (ADS)

    En, Luo

    1992-02-01

    According to the basic idea of dual-complementarity, in a simple and unified way proposed by the author[1], various energy principles in theory of elastic materials with voids can be established systematically. In this paper, an important integral relation is given, which can be considered essentially as the generalized pr. inciple of virtual work. Based on this relation, it is possible not only to obtain the principle of virtual work and the reciprocal theorem of work in theory of elastic materials with voids, but also to derive systematically the complementary functionals for the eight-field, six-field, four-field and two-field generalized variational principles, and the principle of minimum potential and complementary energies. Furthermore, with this appro ach, the intrinsic relationship among various principles can be explained clearly.

  18. Study on voids of epoxy matrix composites sandwich structure parts

    NASA Astrophysics Data System (ADS)

    He, Simin; Wen, Youyi; Yu, Wenjun; Liu, Hong; Yue, Cheng; Bao, Jing

    2017-03-01

    Void is the most common tiny defect of composite materials. Porosity is closely related to composite structure property. The voids forming behaviour in the composites sandwich structural parts with the carbon fiber reinforced epoxy resin skins was researched by adjusting the manufacturing process parameters. The composites laminate with different porosities were prepared with the different process parameter. The ultrasonic non-destructive measurement method for the porosity was developed and verified through microscopic examination. The analysis results show that compaction pressure during the manufacturing process had influence on the porosity in the laminate area. Increasing the compaction pressure and compaction time will reduce the porosity of the laminates. The bond-line between honeycomb core and carbon fiber reinforced epoxy resin skins were also analyzed through microscopic examination. The mechanical properties of sandwich structure composites were studied. The optimization process parameters and porosity ultrasonic measurement method for composites sandwich structure have been applied to the production of the composite parts.

  19. The ISW imprints of voids and superclusters on the CMB

    NASA Astrophysics Data System (ADS)

    Hotchkiss, S.; Nadathur, S.; Gottlöber, S.; Iliev, I. T.; Knebe, A.; Watson, W. A.; Yepes, G.

    2016-10-01

    We examine the stacked integrated Sachs-Wolfe (ISW) imprints on the CMB along the lines of sight of voids and superclusters in galaxy surveys, using the Jubilee ISW simulation and mock luminous red galaxy (LRG) catalogues. We show that the expected signal in the concordance \\Lam CDM model is much smaller than the primary anisotropies arising at the last scattering surface and therefore any currently claimed detections of such an imprint cannot be caused by the ISW effect in \\Lam CDM. We look for the existence of such a signal in the Planck CMB using a catalogue of voids and superclusters from the Sloan Digital Sky Survey (SDSS), but find a result completely consistent with \\Lam CDM - i.e., a null detection.

  20. On the void explanation of the Cold Spot

    NASA Astrophysics Data System (ADS)

    Marcos-Caballero, A.; Fernández-Cobos, R.; Martínez-González, E.; Vielva, P.

    2016-07-01

    The integrated Sachs-Wolfe (ISW) contribution induced on the cosmic microwave background by the presence of a supervoid as the one detected by Szapudi et al. (2015) is reviewed in this letter in order to check whether it could explain the Cold Spot (CS) anomaly. Two different models, previously used for the same purpose, are considered to describe the matter density profile of the void: a top hat function and a compensated profile produced by a Gaussian potential. The analysis shows that, even enabling ellipticity changes or different values for the dark-energy equation of state parameter ω, the ISW contribution due to the presence of the void does not reproduce the properties of the CS.

  1. Comparison results of MOPITT, AIRS and IASI data with ground-based spectroscopic measurements of CO and CH4 total contents

    NASA Astrophysics Data System (ADS)

    Rakitin, Vadim; Elansky, Nikolai; Shtabkin, Yury; Skorokhod, Andrey; Grechko, Eugeny; Pankratova, Natalia; Safronov, Alexandr

    2016-04-01

    A comparative analysis of satellite and ground-based spectroscopic measurements of CO and CH4 total content (CO TC) in the atmosphere in the background and polluted conditions (stations of OIAP RAS and NDACC) for the 2010-2015 time-period. The significant correlation between satellite and ground-based CO TC data for all satellite sensors in background conditions was obtained. Also the empirical private transient relationships between satellite CO MOPITT v6 Joint, AIRS v6, IASI MeTop-A products and the data of solar-tracking ground-based spectrometers are analyzed. Significant correlation between satellite and ground-based data of CO TC was obtained for all satellite sensors if measurements were carried out over unpolluted areas (2010-2014). It was shown that for polluted areas IASI MetOp-A and AIRSv6 data underestimate the actual value of CO TC by the factor of 1.5÷ 2.8. The average correlation between satellite and ground-based data increased significantly for the case if the measurement days, when the height of the planetary boundary layer (PBL) was less than 400-500 meters, were excluded from the comparison. This result was obtained for all of the selected sensors and observational sites. To improve the representativeness of the satellite CO TC data for polluted areas it could be recommended to exclude the days with low height of the PBL from the analysis of spatio-temporal variations and subsequent data assimilation (as example for the CO emissions estimating from powerful surface sources). Best correlation (R2≥0.5) in diurnal CH4 TC with ground-based data was found for AIRS v6. This work has supported by the Russian Scientific Foundation under grant №14-47-00049 and partially by the Russian Foundation for Basic Research (grant № 13-05-41395).

  2. A new least-squares transport equation compatible with voids

    SciTech Connect

    Hansen, J. B.; Morel, J. E.

    2013-07-01

    We define a new least-squares transport equation that is applicable in voids, can be solved using source iteration with diffusion-synthetic acceleration, and requires only the solution of an independent set of second-order self-adjoint equations for each direction during each source iteration. We derive the equation, discretize it using the S{sub n} method in conjunction with a linear-continuous finite-element method in space, and computationally demonstrate various of its properties. (authors)

  3. A method for determining void arrangements in inverse opals.

    PubMed

    Blanford, C F; Carter, C B; Stein, A

    2004-12-01

    The periodic arrangement of voids in ceramic materials templated by colloidal crystal arrays (inverse opals) has been analysed by transmission electron microscopy. Individual particles consisting of an approximately spherical array of at least 100 voids were tilted through 90 degrees along a single axis within the transmission electron microscope. The bright-field images of these particles at high-symmetry points, their diffractograms calculated by fast Fourier transforms, and the transmission electron microscope goniometer angles were compared with model face-centred cubic, body-centred cubic, hexagonal close-packed, and simple cubic lattices in real and reciprocal space. The spatial periodicities were calculated for two-dimensional projections. The systematic absences in these diffractograms differed from those found in diffraction patterns from three-dimensional objects. The experimental data matched only the model face-centred cubic lattice, so it was concluded that the packing of the voids (and, thus, the polymer spheres that composed the original colloidal crystals) was face-centred cubic. In face-centred cubic structures, the stacking-fault displacement vector is a/6<211> . No stacking faults were observed when viewing the inverse opal structure along the orthogonal <110>-type directions, eliminating the possibility of a random hexagonally close-packed structure for the particles observed. This technique complements synchrotron X-ray scattering work on colloidal crystals by allowing both real-space and reciprocal-space analysis to be carried out on a smaller cross-sectional area.

  4. Using Digital Radiography To Image Liquid Nitrogen in Voids

    NASA Technical Reports Server (NTRS)

    Cox, Dwight; Blevins, Elana

    2007-01-01

    Digital radiography by use of (1) a field-portable x-ray tube that emits low-energy x rays and (2) an electronic imaging x-ray detector has been found to be an effective technique for detecting liquid nitrogen inside voids in thermal-insulation panels. The technique was conceived as a means of investigating cryopumping (including cryoingestion) as a potential cause of loss of thermal insulation foam from space-shuttle external fuel tanks. The technique could just as well be used to investigate cryopumping and cryoingestion in other settings. In images formed by use of low-energy x-rays, one can clearly distinguish between voids filled with liquid nitrogen and those filled with gaseous nitrogen or other gases. Conventional film radiography is of some value, but yields only non-real-time still images that do not show time dependences of levels of liquids in voids. In contrast, the present digital radiographic technique yields a succession of images in real time at a rate of about 10 frames per second. The digitized images can be saved for subsequent analysis to extract data on time dependencies of levels of liquids and, hence, of flow paths and rates of filling and draining. The succession of images also amounts to a real-time motion picture that can be used as a guide to adjustment of test conditions.

  5. Calcium polyphosphate particulates for bone void filler applications.

    PubMed

    Pilliar, Robert M; Kandel, Rita A; Grynpas, Marc D; Theodoropoulos, John; Hu, Youxin; Allo, Bedilu; Changoor, Adele

    2016-02-01

    This study investigates the characteristics of porous calcium polyphosphate particulates (CPPp) formed using two different processing treatments as bone void fillers in non- or minimally load-bearing sites. The two calcium polyphosphate particulate variants (grades) were formed using different annealing conditions during particulate preparation to yield either more slowly degrading calcium polyphosphate particulates (SD-CPPp) or faster degrading particulates (FD-CPPp) as suggested by a previous degradation study conducted in vitro (Hu et al., Submitted for publication 2016). The two CPPp grades were compared as bone void fillers in vivo by implanting particulates in defects created in rabbit femoral condyle sites (critical size defects). The SD-CPPp and FD-CPPp were implanted for 4- and 16-week periods. The in vivo study indicated a significant difference in amount of new bone formed in the prepared sites with SD-CPPp resulting in more new bone formation compared with FD-CPPp. The lower bone formation characteristic of the FD-CPPp was attributed to its faster degradation rate and resulting higher local concentration of released polyphosphate degradation products. The study results indicate the importance of processing conditions on preparing calcium polyphosphate particulates for potential use as bone void fillers in nonload-bearing sites. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  6. Stem cell therapy for voiding and erectile dysfunction

    PubMed Central

    Vaegler, Martin; Lenis, Andrew T; Daum, Lisa; Renninger, M; Bastian, Amend; Stenzl, Arnulf; Damaser, Margot S; Sievert, Karl-Dietrich

    2013-01-01

    Voiding dysfunction comprises a variety of disorders, including stress urinary incontinence and overactive bladder, and affects millions of men and women worldwide. Erectile dysfunction (ED) also decreases quality of life for millions of men, as well as for their partners. Advanced age and diabetes are common comorbidities that can exacerbate and negatively impact upon the development of these disorders. Therapies that target the pathophysiology of these conditions to halt progression are not currently available. However, stem cell therapy could fill this therapeutic void. Stem cells can reduce inflammation, prevent fibrosis, promote angiogenesis, recruit endogenous progenitor cells, and differentiate to replace damaged cells. Adult multipotent stem cell therapy, in particular, has shown promise in case reports and preclinical animal studies. Stem cells have also enabled advances in urological tissue engineering by facilitating ex vivo construction of bladder wall and urethral tissue (using a patient's own cells) prior to transplantation. More recent studies have focused on bioactive factor secretion and homing of stem cells. In the future, clinicians are likely to utilize allogeneic stem cell sources, intravenous systemic delivery, and ex vivo cell enhancement to treat voiding dysfunction and ED. PMID:22710667

  7. Pulsed electrical breakdown of a void-filled dielectric

    NASA Astrophysics Data System (ADS)

    Anderson, R. A.; Lagasse, R. R.; Schroeder, J. L.

    2002-05-01

    We report breakdown strengths in a void-filled dielectric material, epoxy containing 48 vol % hollow glass microballoon filler, which is stressed with unipolar voltage pulses of the order of 10 μs duration. The microballoon voids had mean diameters of approximately 40 μm and contained SO2 gas at roughly 30% atmospheric pressure. This void-filled material displays good dielectric strength (of the order of 100 kV mm-1) under these short-pulse test conditions. Results from a variety of electrode geometries are reported, including arrangements in which the electric stress is highly nonuniform. Conventional breakdown criteria based on mean or peak electric stress do not account for these data. A statistics-based predictive breakdown model is developed, in which the dielectric is divided into independent, microballoon-sized "discharge cells" and the spontaneous discharge of a single cell is presumed to launch full breakdown of the composite. We obtain two empirical parameters, the mean and standard deviation of the spontaneous discharge field, by fitting breakdown data from two electrode geometries having roughly uniform fields but with greatly differing volumes of electrically stressed material. This model accounts for many aspects of our data, including the inherent statistical scatter and the dependence on the stressed volume, and it provides informative predictions with electrode geometries giving highly nonuniform fields. Issues related to computational spatial resolution and cutoff distance are also discussed.

  8. Void-free epoxy castings for cryogenic insulators and seals

    SciTech Connect

    Quirk, J.F.

    1983-01-01

    The design of the Westinghouse Magnet for the Oak Ridge National Laboratory's Large Coil Program (LCP) incorporates a main lead bushing which transmits heat-leak loads by conduction to the supercritical helium stream. The bushing, which consists of epoxy resin cast about a copper conductor, must be electrically insulated, vacuum tight and be capable of withstanding the stresses encountered in cryognic service. The seal design of the bushing is especially important; leakage from either the helium system or the external environment into the vacuum will cause the magnet to quench. Additionally, the epoxy-resin casting must resist mechanical loads caused by the weight of leads attached to the bushing and thermal stresses transmitted to the epoxy via the conductor. The epoxy resin is cast about the conductor in such a way as to provide the required vacuum tight seal. The technique by which this is accomplished is reviewed. Equally important is the elimination of voids in the epoxy which will act as stress-concentrating discontinuities during cooling to or warming from 4K. The types of voids that could be expected and their causes are described. The paper reviews techniques employed to eliminate voids within the cast-resin portion of the bushing.

  9. Confirmation of sublunarean voids and thin layering in mare deposits

    NASA Astrophysics Data System (ADS)

    Robinson, M. S.; Ashley, J. W.; Boyd, A. K.; Wagner, R. V.; Speyerer, E. J.; Ray Hawke, B.; Hiesinger, H.; van der Bogert, C. H.

    2012-08-01

    Typical flow thicknesses of lunar mare basalts were not well constrained in the past, because as craters and rilles age, downslope movement of loose material tends to mix and bury stratigraphy, obscuring the three dimensional nature of the maria. New Lunar Reconnaissance Orbiter Camera high resolution images unambiguously reveal thicknesses of mare basalt layers exposed in impact craters, rilles, and steep-walled pits. Pits up to one hundred meters deep present relatively unmodified, near-vertical sections of mare in three cases, and many young impact craters also expose well preserved sections of mare. Oblique views of each pit and many of these craters reveal multiple layers, 3 to 14 m thick, indicating that eruptions typically produced a series of ˜10 m thick flows (or flow lobes) rather than flows many tens to hundreds of meters thick. Additionally, these images unambiguously show that the floors of two pits extend beneath the mare surfaces, thus revealing sublunarean voids of unknown lateral extent. We also document the occurrence of pits that may be expressions of collapse into subsurface voids in non-mare impact melt deposits. These voids are compelling targets for future human and robotic exploration, with potential as temporary shelters, habitations, or geologic museums.

  10. The distribution of IRAS galaxies towards the Bootes void

    NASA Technical Reports Server (NTRS)

    Strauss, Michael A.; Huchra, John

    1988-01-01

    A redshift survey was completed for 342 galaxies detected by the IRAS in the direction of the Bootes void discovered by Kirshner et al. The number density of IRAS galaxies is well determined from the shallower full-sky redshift survey of Strauss et al. Four IRAS galaxies are found within the void as defined by Kirshner et al., of which three are part of a complete sample, implying a density depression of a factor of 4. The underdense region continues to a distance of at least 4000 km/s from the nominal center of the void. Three of the IRAS galaxies studied in this paper were previously unknown. These galaxies have emission-line spectra characteristic of H II regions, and red continuum magnitudes ranging from 16 to 17.5 mag, and thus are bright enough to have been detected in a wide-angle redshift survey as deep as that of Kirshner et al. The luminosity function derived from this sample is in good agreement with that of Lawrence et al.

  11. A novel low-cost open-hardware platform for monitoring soil water content and multiple soil-air-vegetation parameters.

    PubMed

    Bitella, Giovanni; Rossi, Roberta; Bochicchio, Rocco; Perniola, Michele; Amato, Mariana

    2014-10-21

    Monitoring soil water content at high spatio-temporal resolution and coupled to other sensor data is crucial for applications oriented towards water sustainability in agriculture, such as precision irrigation or phenotyping root traits for drought tolerance. The cost of instrumentation, however, limits measurement frequency and number of sensors. The objective of this work was to design a low cost "open hardware" platform for multi-sensor measurements including water content at different depths, air and soil temperatures. The system is based on an open-source ARDUINO microcontroller-board, programmed in a simple integrated development environment (IDE). Low cost high-frequency dielectric probes were used in the platform and lab tested on three non-saline soils (ECe1: 2.5 < 0.1 mS/cm). Empirical calibration curves were subjected to cross-validation (leave-one-out method), and normalized root mean square error (NRMSE) were respectively 0.09 for the overall model, 0.09 for the sandy soil, 0.07 for the clay loam and 0.08 for the sandy loam. The overall model (pooled soil data) fitted the data very well (R2 = 0.89) showing a high stability, being able to generate very similar RMSEs during training and validation (RMSE(training) = 2.63; RMSE(validation) = 2.61). Data recorded on the card were automatically sent to a remote server allowing repeated field-data quality checks. This work provides a framework for the replication and upgrading of a customized low cost platform, consistent with the open source approach whereby sharing information on equipment design and software facilitates the adoption and continuous improvement of existing technologies.

  12. A Novel Low-Cost Open-Hardware Platform for Monitoring Soil Water Content and Multiple Soil-Air-Vegetation Parameters

    PubMed Central

    Bitella, Giovanni; Rossi, Roberta; Bochicchio, Rocco; Perniola, Michele; Amato, Mariana

    2014-01-01

    Monitoring soil water content at high spatio-temporal resolution and coupled to other sensor data is crucial for applications oriented towards water sustainability in agriculture, such as precision irrigation or phenotyping root traits for drought tolerance. The cost of instrumentation, however, limits measurement frequency and number of sensors. The objective of this work was to design a low cost “open hardware” platform for multi-sensor measurements including water content at different depths, air and soil temperatures. The system is based on an open-source ARDUINO microcontroller-board, programmed in a simple integrated development environment (IDE). Low cost high-frequency dielectric probes were used in the platform and lab tested on three non-saline soils (ECe1: 2.5 < 0.1 mS/cm). Empirical calibration curves were subjected to cross-validation (leave-one-out method), and normalized root mean square error (NRMSE) were respectively 0.09 for the overall model, 0.09 for the sandy soil, 0.07 for the clay loam and 0.08 for the sandy loam. The overall model (pooled soil data) fitted the data very well (R2 = 0.89) showing a high stability, being able to generate very similar RMSEs during training and validation (RMSEtraining = 2.63; RMSEvalidation = 2.61). Data recorded on the card were automatically sent to a remote server allowing repeated field-data quality checks. This work provides a framework for the replication and upgrading of a customized low cost platform, consistent with the open source approach whereby sharing information on equipment design and software facilitates the adoption and continuous improvement of existing technologies. PMID:25337742

  13. A nonlinear theory of dust voids in cylindrical geometry with the convective effect

    SciTech Connect

    Liu Yue; Mao Songtao; Wang Zhengxiong; Wang Xiaogang

    2006-06-15

    A time-dependent, self-consistent nonlinear model with the convective term for the void formation in dusty plasmas is given. Furthermore, the cylindrical configuration is applied instead of the Cartesian system, considering the device geometry in experiments. The nonlinear evolution of the dust void is then investigated numerically. It is shown that, similar to the slab model, the ion drag plays a crucial role in the evolution of the void. However, the effect of the convective term slows down the void formation process and the void size obtained in the cylindrical coordinate is larger than that obtained in the Cartesian coordinates.

  14. Reliability of scanning laser acoustic microscopy for detecting internal voids in structural ceramics

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Baaklini, G. Y.

    1986-01-01

    The reliability of 100 MHz scanning laser acoustic microscopy (SLAM) for detecting internal voids in sintered specimens of silicon nitride and silicon carbide was evaluated. The specimens contained artificially implanted voids and were positioned at depths ranging up to 2 mm below the specimen surface. Detection probability of 0.90 at a 0.95 confidence level was determined as a function of material, void diameter, and void depth. The statistical results presented for void detectability indicate some of the strengths and limitations of SLAM as a nondestructive evaluation technique for structural ceramics.

  15. Specimen preparation and image processing and analysis techniques for automated quantification of concrete microcracks and voids

    SciTech Connect

    Soroushian, Parviz; Elzafraney, Mohamed; Nossoni, Ali

    2003-12-01

    Specimen preparation and image processing/analysis techniques were developed for use in automated quantitative microstructural investigation of concrete, focusing on concrete microcracks and voids. Different specimen preparation techniques were developed for use in fluorescent and scanning electron microscopy (SEM) of concrete; then techniques produce a sharp contrast between microcracks/voids and the body of concrete. The image processing/analysis techniques developed specifically for use with concrete address the following usages: automatic threshold; development of intersecting microcracks/voids and connected voids; distinction of microcracks form voids based on geometric attributes; and noise filtration.

  16. Quantitative void characterization in structural ceramics using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Generazio, E. R.; Baaklini, G. Y.

    1986-01-01

    The ability of scanning laser acoustic microscopy (SLAM) to characterize artificially seeded voids in sintered silicon nitride structural ceramic specimens was investigated. Using trigonometric relationships and Airy's diffraction theory, predictions of internal void depth and size were obtained from acoustic diffraction patterns produced by the voids. Agreement was observed between actual and predicted void depths. However, predicted void diameters were generally much greater than actual diameters. Precise diameter predictions are difficult to obtain due to measurement uncertainty and the limitations of 100 MHz SLAM applied to typical ceramic specimens.

  17. Is the far border of the Local Void expanding?

    NASA Astrophysics Data System (ADS)

    Iwata, I.; Chamaraux, P.

    2011-07-01

    Context. According to models of evolution in the hierarchical structure formation scenarios, voids of galaxies are expected to expand. The Local Void (LV) is the closest large void, and it provides a unique opportunity to test observationally such an expansion. It has been found that the Local Group, which is on the border of the LV, is running away from the void center at ~260 km s-1. Aims: In this study we investigate the motion of the galaxies at the far-side border of the LV to examine the presence of a possible expansion. Methods: We selected late-type, edge-on spiral galaxies with radial velocities between 3000 km s-1 and 5000 km s-1, and carried out HI 21 cm line and H-band imaging observations. The near-infrared Tully-Fisher relation was calibrated with a large sample of galaxies and carefully corrected for Malmquist bias. It was used to compute the distances and the peculiar velocities of the LV sample galaxies. Among the 36 sample LV galaxies with good quality HI line width measurements, only 15 galaxies were selected for measuring their distances and peculiar velocities, in order to avoid the effect of Malmquist bias. Results: The average peculiar velocity of these 15 galaxies is found to be -419+208-251 km s-1, which is not significantly different from zero. Conclusions: Due to the intrinsically large scatter of Tully-Fisher relation, we cannot conclude whether there is a systematic motion against the center of the LV for the galaxies at the far-side boundary of the void. However, our result is consistent with the hypothesis that those galaxies at the far-side boundary have an average velocity of ~260 km s-1 equivalent to what is found at the position of the Local Group. Based on data taken at Nançay radiotelescope operated by Observatoire de Paris, CNRS and Université d'Orléans, Infrared Survey Facility (IRSF) which is operated by Nagoya university under the cooperation of South African Astronomical Observatory, Kyoto University, and National

  18. On the energetics of tensile and shear void coalescences

    NASA Astrophysics Data System (ADS)

    Wong, W. H.; Guo, T. F.

    2015-09-01

    This paper investigates the mechanisms of tensile and shear void coalescences in ductile materials from energetics perspective. By examining and comparing the elastic and plastic energies of a voided cell throughout its deformation history, the onset of and final coalescence can be distinctly established. This energy-based approach offers a single unified method and criterion for determining the occurrences of both mechanisms. This paper also reports a novel micromechanics model that considers general stress states described by three macroscopic normal stresses and one macroscopic shear stress. Detailed formulation of the model is presented that includes the homogenization-based derivation and implementation of a 4×4 orthogonal transformation matrix, which relates the macroscopic deformation rate of the cell to displacement rates of non-physical degrees-of-freedom (DOFs), and the polar decomposition of the macroscopic deformation gradient tensor which admits the explicit determination of the logarithmic strain measures and rotation angle. In terms of stress ratios, ρ1 (=Σ11 /Σ22) ,ρ2 (=Σ12 /Σ22) ,ρ3 (=Σ33 /Σ22), it is analytically shown that multiple macroscopic stress states {ρ1 ,ρ2 ,ρ3 } can exist that result in the same stress triaxiality T and Lode parameter L. Specifically, it is shown that for a prescribed pair of T and L and in the absence of shear stress, at most six stress states {ρ1 , 0 ,ρ3 } are possible. On the other extreme in the presence of shear stress, an infinite number of stress states is possible, due to the existence of Mohr's circle for this stress state. This model, together with the proposed energy-based criteria, is used to examine void coalescence under multiple stress-state conditions for any given T and L. Numerical results have shown that the presence of shear stress has a significant effect of reducing the effective strains for the onset of and final void coalescences. In addition, a relationship has also been

  19. Effect of water vapour condensation on the radon content in subsurface air in a hypogeal inactive-volcanic environment in Galdar cave, Spain

    NASA Astrophysics Data System (ADS)

    Fernandez-Cortes, A.; Benavente, D.; Cuezva, S.; Cañaveras, J. C.; Alvarez-Gallego, M.; Garcia-Anton, E.; Soler, V.; Sanchez-Moral, S.

    2013-08-01

    Fluctuations of trace gas activity as a response to variations in weather and microclimate conditions were monitored over a year in a shallow volcanic cave (Painted Cave, Galdar, Canary Islands, Spain). 222Rn concentration was used due to its greater sensitivity to hygrothermal variations than CO2 concentration. Radon concentration in the cave increases as effective vapour condensation within the porous system of the rock surfaces inside the cave increases due to humidity levels of more than 70%. Condensed water content in pores was assessed and linked to a reduction in the direct passage of trace gases. Fluctuations in radon activity as a response to variations in weather and microclimate conditions were statistically identified by clustering entropy changes on the radon signal and parameterised to predict radon concentration anomalies. This raises important implications for other research fields, including the surveillance of shallow volcanic and seismic activity, preventive conservation of cultural heritage in indoor spaces, indoor air quality control and studies to improve understanding of the role of subterranean terrestrial ecosystems as reservoirs and/or temporary sources of trace gases.

  20. [Use of laser flow-type fluorescence aerosol particle counter to evaluate the concentration of microbes in the surface air under high dust content].

    PubMed

    Kalinin, Iu T; Vorob'ev, S A; Khramov, E N; Vorob'eva, E A; Kuznetsov, A P; Kiselev, O S

    2000-01-01

    The paper deals with the use of a laser flow-type fluorescence aerosol particle counter to evaluate the concentrations of microbes in the surface air under high dust content. Various circuits of flow-type optic aerosol recorders are analyzed. Flow spectral luminescence analysis of some particles flow while exciting the fourth harmonics of a pulse laser on yttrium-aluminium garnet with neodymium by ultraviolet radiation is shown to be the most optimum method for indication of individual aerosol particles. Experiments were conducted on the authors' model of a pilot plant based on this method. The model of a laser flow-type optic analyzer was developed for experimental studies that give a clear display of biological aerosols in complex aerosols. The laser flow-type analyzer-based unit developed may provide a fluorescence signal of aerosol particles in the flow of a sample and that light diffusion signal from them at an exciting light wavelength of 266 nm. Experiments with BVC aerosols and soil dust particles were conducted in different regions of Russia. They showed it possible to detect and to rapidly calculate soil microorganisms by laser flow-type fluorescence assay of individual particles when excited by ultraviolet radiation.

  1. Air pollution particles mediated oxidative DNA base damage in a cell free system and in human airway epithelial cells in relation to particulate metal content and bioreactivity.

    PubMed

    Prahalad, A K; Inmon, J; Dailey, L A; Madden, M C; Ghio, A J; Gallagher, J E

    2001-07-01

    Epidemiological studies demonstrate an association between increased human morbidity and mortality with exposure to air pollution particulate matter. We hypothesized that such effects may be associated with the ability of the particles to mediate generation of reactive oxygen species (ROS), either directly, via interaction with ambient oxygen or indirectly through initiation of an oxidative burst in phagocytes. To test this hypothesis, we determined 8-oxo-dG formation as a measure of direct generation of ROS, in response to particulate exposures to 2'-deoxyguanosine (dG), free and in calf thymus DNA in aerated solutions as the target molecule and cell culture, to assess the relationship between induction of oxidative damage, particulate metal content and metal bioreactivity. The HPLC-ECD technique was employed for separation and quantification of 8-oxo-dG, the most widely recognized marker of DNA oxidation. Particles used in this study include: Arizona desert dust (AZDD), coal fly ash (CFA and ECFA), oil fly ash (OFA and ROFA), and ambient air [SRM 1649 and Dusseldorf (DUSS), Germany]. The major difference between these particles is the concentration of water-soluble metals. The fly ash particulates OFA and ROFA showed a significant dose-dependent increase in dG hydroxylation to 8-oxo-dG formation over the control dG (p < 0.05), with yields 0.03 and 1.25% at the highest particulate concentration (1 mg/mL). Metal ion chelators and DMSO, a hydroxyl radical scavenger, inhibited this hydroxylation. In contrast, desert dust, coal fly ash and urban air particles induced 8-oxo-dG with yields ranging from 0.003 to 0.006%, respectively, with levels unaffected by pretreatment of the particles with metal ion chelators or addition of DMSO to the incubation mixture. When calf thymus DNA was used as a substrate, all the particles induced 8-oxo-dG in a pattern similar to that observed for dG hydroxylation, but with relatively less yield. Treatment of the particles with metal ion

  2. Ultrasonic attenuation of a void-containing medium for very long wavelengths

    NASA Technical Reports Server (NTRS)

    Williams, J. H., Jr.; Lee, S. S.; Yuece, H.

    1983-01-01

    Ultrasonic longitudinal through-thickness attenuation in an isotropic medium due to scattering by randomly distributed voids is considered analytically. The attenuation is evaluated on the assumption of no interaction between voids. The scattered power is assumed to be entirely lost, thus accounting for the ultrasonic attenuation. The scattered power due to the presence of a void is described in terms of the scattering cross section of the void. An exact solution exists for the scattering cross section of a spherical void. An approximate solution for the scattering cross section of an ellipsoidal void is developed based on the so-called Born approximation commonly used in quantum mechanics. This approximate solution is valid for k sub p a sub i 1, where k sub p is the wave number of the incident longitudinal wave and a sub i is the largest dimension of the void. It is found that the shape of the void has negligible effect on the scattering cross section and that only the volume of the void is important. Thus, it is noted that in cases where k sup p a sub i 1, the exact scattering cross section of a spherical void having the same volume as an arbitrarily shaped void can be used for evaluating ultrasonic attenuation.

  3. Theoretical analysis of electromigration-induced failure of metallic thin films due to transgranular void propagation

    SciTech Connect

    Gungor, M.R.; Maroudas, D.

    1999-02-01

    Failure of metallic thin films driven by electromigration is among the most challenging materials reliability problems in microelectronics toward ultra-large-scale integration. One of the most serious failure mechanisms in thin films with bamboo grain structure is the propagation of transgranular voids, which may lead to open-circuit failure. In this article, a comprehensive theoretical analysis is presented of the complex nonlinear dynamics of transgranular voids in metallic thin films as determined by capillarity-driven surface diffusion coupled with drift induced by electromigration. Our analysis is based on self-consistent dynamical simulations of void morphological evolution and it is aided by the conclusions of an approximate linear stability theory. Our simulations emphasize that the strong dependence of surface diffusivity on void surface orientation, the strength of the applied electric field, and the void size play important roles in the dynamics of the voids. The simulations predict void faceting, formation of wedge-shaped voids due to facet selection, propagation of slit-like features emanating from void surfaces, open-circuit failure due to slit propagation, as well as appearance and disappearance of soliton-like features on void surfaces prior to failure. These predictions are in very good agreement with recent experimental observations during accelerated electromigration testing of unpassivated metallic films. The simulation results are used to establish conditions for the formation of various void morphological features and discuss their serious implications for interconnect reliability. {copyright} {ital 1999 American Institute of Physics.}

  4. Direct evidence of void passivation in Cu(InGa)(SSe){sub 2} absorber layers

    SciTech Connect

    Lee, Dongho; Kim, Young-Su; Mo, Chan B.; Huh, Kwangsoo; Yang, JungYup E-mail: ddang@korea.ac.kr; Nam, Junggyu; Baek, Dohyun; Park, Sungchan; Kim, ByoungJune; Kim, Dongseop; Lee, Jaehan; Heo, Sung; Park, Jong-Bong; Kang, Yoonmook E-mail: ddang@korea.ac.kr

    2015-02-23

    We have investigated the charge collection condition around voids in copper indium gallium sulfur selenide (CIGSSe) solar cells fabricated by sputter and a sequential process of selenization/sulfurization. In this study, we found direct evidence of void passivation by using the junction electron beam induced current method, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The high sulfur concentration at the void surface plays an important role in the performance enhancement of the device. The recombination around voids is effectively suppressed by field-assisted void passivation. Hence, the generated carriers are easily collected by the electrodes. Therefore, when the S/(S + Se) ratio at the void surface is over 8% at room temperature, the device performance degradation caused by the recombination at the voids is negligible at the CIGSSe layer.

  5. High-temperature healing of interfacial voids in GaAs wafer bonding

    NASA Astrophysics Data System (ADS)

    Wu, YewChung Sermon; Liu, Po Chun; Feigelson, R. S.; Route, R. K.

    2002-02-01

    Artificial voids were introduced at bonding interfaces to study how processing parameters affected the healing mechanism of interfacial voids in GaAs wafer bonding. These voids were created by placing unpatterned wafers in contact with topographically patterned wafers. During the bonding process, crystallites formed within these voids and corresponded to bonded regions within the voids. Their formation depended strongly on the height of the surface irregularities at the wafer interfaces. When the void depth (h) was ⩾200 nm, most of the crystallites were diamond shaped. The edges of the diamond features were elongated in the <100> direction. On the other hand, when the void depth was small (h⩽70 nm), dendrites grew quickly in the <110> direction.

  6. THE WEIGHT OF EMPTINESS: THE GRAVITATIONAL LENSING SIGNAL OF STACKED VOIDS

    SciTech Connect

    Krause, Elisabeth; Dore, Olivier; Chang, Tzu-Ching; Umetsu, Keiichi

    2013-01-10

    The upcoming new generation of spectroscopic galaxy redshift surveys will provide large samples of cosmic voids, large distinct, underdense structures in the universe. Combining these with future galaxy imaging surveys, we study the prospects of probing the underlying matter distribution in and around cosmic voids via the weak gravitational lensing effects of stacked voids, utilizing both shear and magnification information. The statistical precision is greatly improved by stacking a large number of voids along different lines of sight, even when taking into account the impact of inherent miscentering and projection effects. We show that Dark Energy Task Force Stage IV surveys, such as the Euclid satellite and the Large Synoptic Survey Telescope, should be able to detect the void lensing signal with sufficient precision from stacking abundant medium-sized voids, thus providing direct constraints on the matter density profile of voids independent of assumptions on galaxy bias.

  7. White Cells and Bacteria in Voided Urine of Healthy Newborns

    PubMed Central

    Littlewood, James M.

    1971-01-01

    During a screening survey for urinary infection, 600 infants had one or more urines examined on the sixth or seventh day of life and 592 were subsequently shown to be uninfected. Bacterial and white cell counts on the first urine specimen to be examined from each infant are reported, comprising 363 specimens (188 from boys, 177 from girls) collected into plastic bags and 229 specimens (116 from boys, 113 from girls) collected by a clean catch technique. Bag specimens contained 5 white cells per mm3 or less in 98% of boys but in only 56% of girls, in whom 11% contained more than 100 white cells per mm3. Clean catch specimens contained up to 5 white cells per mm3 in 97% of boys and 94% of girls, suggesting perineal contamination in girls to be the cause of the higher white cell counts in urine collected into plastic bags. Total bacterial counts of 10,000 colonies per ml or less were obtained from bag urines in 41% of both boys and girls and from midstream urines of 73% of boys and 77% of girls. Midstream specimens were significantly better than bag specimens for purposes of culture. Examination of voided urine specimens from newborns allows infection to be excluded in approximately 45% of infants if only one bag specimen is examined and in approximately 75% if a single midstream specimen is obtained. Even bag specimens are therefore not without value. Suprapubic aspiration should be reserved for infants where difficulty arises due to repeated equivocal results from voided urines, when urgent confirmation is required, or when the presence of perineal lesions makes suitable voided urine collection impracticable. PMID:5576025

  8. Topology and dark energy: testing gravity in voids.

    PubMed

    Spolyar, Douglas; Sahlén, Martin; Silk, Joe

    2013-12-13

    Modified gravity has garnered interest as a backstop against dark matter and dark energy (DE). As one possible modification, the graviton can become massive, which introduces a new scalar field--here with a Galileon-type symmetry. The field can lead to a nontrivial equation of state of DE which is density and scale dependent. Tension between type Ia supernovae and Planck could be reduced. In voids, the scalar field dramatically alters the equation of state of DE, induces a soon-observable gravitational slip between the two metric potentials, and develops a topological defect (domain wall) due to a nontrivial vacuum structure for the field.

  9. Urethane foam void filling. Innovative technology summary report

    SciTech Connect

    1998-12-01

    Under the decontamination and decommissioning (D and D) Implementation Plan of the United States Department of Energy`s (DOE`s) Fernald Environmental Management Project (FEMP), non-recyclable process components and debris that are removed from buildings undergoing D and D are disposed of in an on-site disposal facility (OSDF). Critical to the design and operation of the FEMP`s OSDF are provisions to protect against subsidence of the OSDF`s cap. Subsidence of the cap could occur if void spaces within the OSDF were to collapse under the overburden of debris and the OSDF cap. Subsidence may create depressions in the OSDF`s cap in which rainwater could collect and eventually seep into the OSDF. To minimize voids in the FEMP`s OSDF, large metallic components are cut into smaller segments that can be arranged more compactly when placed in the OSDF. Component segmentation using an oxy-acetylene torch was the baseline approach used by the FEMP`s D and D contractor on Plant 1, B and W Services, Inc., for the dismantlement and size-reduction of large metal components. Although this technology has performed satisfactorily, it is time-consuming, labor-intensive and costly. Use of the oxy-acetylene torch exposes workers to health and safety hazards including the risk of burns, carbon monoxide, and airborne contamination of residual lead-based paints and other contaminants on the surface of the components being segmented. In addition, solvents used to remove paint from the components before segmenting them emit flammable, noxious fumes. This demonstration investigated the feasibility of placing large vessels intact in the OSDF without segmenting them. To prevent the walls of the vessels from collapsing under the overburden or from degradation, an innovative approach was employed which involved filling the voids in the vessels with a fluid material that hardened on standing. The hardened filling would support the walls of the vessels, and prevent them from collapsing. This report

  10. Large Voids in the Universe are Really Empty

    NASA Astrophysics Data System (ADS)

    1996-07-01

    Motions of Nearby Galaxies Reveal No Invisible Matter Using telescopes in Chile, Europe, Australia and the USA, an international team of astronomers [1] has discovered large empty regions (`holes') in what they refer to as the `local Universe'. These regions, as well as others with excess mass density are revealed by a study of the motions in space of more than 2000 galaxies. They are among the largest structures ever seen in the Universe and have diameters of up to 100 million light years. Large empty regions in the nearby Universe Astronomers have known for a number of years that there are regions in the Universe where no galaxies, stars or gas can be seen by optical telescopes. In professional language, such `holes' are commonly referred to as `voids' . For some time, astronomers around the world have tried to detect at least some galaxies in these voids by using larger and more sensitive telescopes. Amazingly, only few such galaxies have ever been found, even by use of the best available equipment. The failure to detect anything in these voids has led to speculations about the nature of the matter in voids. Could it be that it is there, but not in the form astronomers are best familiar with, namely stars and galaxies which can be detected with modern telescopes? Is it perhaps in some kind of exotic, invisible state? The new study now gives a surprisingly simple answer to that question: There just is no matter in the voids! How to detect the `voids' Astronomers can easily detect normal galaxies at very large distances with the help of technologically advanced optical telescopes, like the ones operated by the European Southern Observatory at La Silla in Chile. It was during such investigations in the 1980's, at ESO and elsewhere, that some `voids' were first found as regions of space where few galaxies could be seen. However, it is very difficult to prove that there is `nothing', i.e. absence of visible as well as invisible matter, in some region of the Universe

  11. Nanovoid growth in BCC α-Fe: influences of initial void geometry

    NASA Astrophysics Data System (ADS)

    Xu, Shuozhi; Su, Yanqing

    2016-12-01

    The growth of voids has a great impact on the mechanical properties of ductile materials by altering their microstructures. Exploring the process of void growth at the nanoscale helps in understanding the dynamic fracture of metals. While some very recent studies looked into the effects of the initial geometry of an elliptic void on the plastic deformation of face-centered cubic metals, a systematic study of the initial void ellipticity and orientation angle in body-centered cubic (BCC) metals is still lacking. In this paper, large scale molecular dynamics simulations with millions of atoms are conducted, investigating the void growth process during tensile loading of metallic thin films in BCC α-Fe. Our simulations elucidate the intertwined influences on void growth of the initial ellipticity and initial orientation angle of the void. It is shown that these two geometric parameters play an important role in the stress-strain response, the nucleation and evolution of defects, as well as the void size/outline evolution in α-Fe thin films. Results suggest that, together with void size, different initial void geometries should be taken into account if a continuum model is to be applied to nanoscale damage progression.

  12. Testing the imprint of nonstandard cosmologies on void profiles using Monte Carlo random walks

    NASA Astrophysics Data System (ADS)

    Achitouv, Ixandra

    2016-11-01

    Using Monte Carlo random walks of a log-normal distribution, we show how to qualitatively study void properties for nonstandard cosmologies. We apply this method to an f (R ) modified gravity model and recover the N -body simulation results of [1 I. Achitouv, M. Baldi, E. Puchwein, and J. Weller, Phys. Rev. D 93, 103522 (2016).] for the void profiles and their deviation from GR. This method can potentially be extended to study other properties of the large scale structures such as the abundance of voids or overdense environments. We also introduce a new way to identify voids in the cosmic web, using only a few measurements of the density fluctuations around random positions. This algorithm allows us to select voids with specific profiles and radii. As a consequence, we can target classes of voids with higher differences between f (R ) and standard gravity void profiles. Finally, we apply our void criteria to galaxy mock catalogues and discuss how the flexibility of our void finder can be used to reduce systematic errors when probing the growth rate in the galaxy-void correlation function.

  13. Atomic-Scale Mechanisms of Void Hardening in BCC and FCC Metals

    SciTech Connect

    Osetskiy, Yury N; Bacon, David J

    2010-01-01

    Strengthening due to voids can be a significant effect of radiation damage in metals, but treatment of this by elasticity theory of dislocations is difficult when the mechanisms controlling the obstacle strength are atomic in nature. Results are reported of atomic-scale modelling to compare edge dislocation-void interaction in fcc copper and bcc iron. Voids of up to 6 nm diameter in iron and 8 nm diameter in copper were studied over the temperature range 0 to 600 K at different applied strain rates. Voids in iron are strong obstacles, for the dislocation has to adopt a dipole-like configuration at the void before breaking away. The dipole unzips at the critical stress when the dislocation is able to climb by absorbing vacancies and leave the void surface. Dislocation dissociation into Shockley partials in copper prevents dislocation climb and affects the strength of small and large voids differently. Small voids are much weaker obstacles than those in iron because the partials break from a void individually. Large voids are at least as strong as those in iron, but the controlling mechanism depends on temperature.

  14. Vegetative Clostridium difficile survives in room air on moist surfaces and in gastric contents with reduced acidity: a potential mechanism to explain the association between proton pump inhibitors and C. difficile-associated diarrhea?

    PubMed

    Jump, Robin L P; Pultz, Michael J; Donskey, Curtis J

    2007-08-01

    Proton pump inhibitors (PPIs) have been identified as a risk factor for Clostridium difficile-associated diarrhea (CDAD), though the mechanism is unclear because gastric acid does not kill C. difficile spores. We hypothesized that the vegetative form of C. difficile, which is killed by acid, could contribute to disease pathogenesis if it survives in room air and in gastric contents with elevated pH. We compared the numbers of C. difficile spores and vegetative cells in stools of patients prior to and during the treatment of CDAD. We assessed the survival of vegetative cells on moist or dry surfaces in room air versus anaerobic conditions and in human gastric contents, in pH-adjusted gastric contents, and in gastric contents from individuals receiving PPI therapy. Stool samples obtained from patients prior to the initiation of antibiotic treatment for C. difficile contained approximately 10-fold more vegetative cells than spores. On dry surfaces, vegetative C. difficile cells died rapidly, whereas they remained viable for up to 6 h on moist surfaces in room air. Vegetative C. difficile cells had only marginal survival in gastric contents at low pH; adjustment to a pH of >5 resulted in survival similar to that in the phosphate-buffered saline control. The survival of vegetative C. difficile in gastric contents obtained from patients receiving PPIs was also increased at a pH of >5. The ability of the vegetative form of C. difficile to survive on moist surfaces and in gastric contents with an elevated pH suggests a potential mechanism by which PPI therapy could increase the risk of acquiring C. difficile.

  15. Statistical geometry of lattice chain polymers with voids of defined shapes: sampling with strong constraints.

    PubMed

    Lin, Ming; Chen, Rong; Liang, Jie

    2008-02-28

    Proteins contain many voids, which are unfilled spaces enclosed in the interior. A few of them have shapes compatible to ligands and substrates and are important for protein functions. An important general question is how the need for maintaining functional voids is influenced by, and affects other aspects of proteins structures and properties (e.g., protein folding stability, kinetic accessibility, and evolution selection pressure). In this paper, we examine in detail the effects of maintaining voids of different shapes and sizes using two-dimensional lattice models. We study the propensity for conformations to form a void of specific shape, which is related to the entropic cost of void maintenance. We also study the location that voids of a specific shape and size tend to form, and the influence of compactness on the formation of such voids. As enumeration is infeasible for long chain polymer, a key development in this work is the design of a novel sequential Monte Carlo strategy for generating large number of sample conformations under very constraining restrictions. Our method is validated by comparing results obtained from sampling and from enumeration for short polymer chains. We succeeded in accurate estimation of entropic cost of void maintenance, with and without an increasing number of restrictive conditions, such as loops forming the wall of void with fixed length, with additionally fixed starting position in the sequence. Additionally, we have identified the key structural properties of voids that are important in determining the entropic cost of void formation. We have further developed a parametric model to predict quantitatively void entropy. Our model is highly effective, and these results indicate that voids representing functional sites can be used as an improved model for studying the evolution of protein functions and how protein function relates to protein stability.

  16. Statistical geometry of lattice chain polymers with voids of defined shapes: Sampling with strong constraints

    NASA Astrophysics Data System (ADS)

    Lin, Ming; Chen, Rong; Liang, Jie

    2008-02-01

    Proteins contain many voids, which are unfilled spaces enclosed in the interior. A few of them have shapes compatible to ligands and substrates and are important for protein functions. An important general question is how the need for maintaining functional voids is influenced by, and affects other aspects of proteins structures and properties (e.g., protein folding stability, kinetic accessibility, and evolution selection pressure). In this paper, we examine in detail the effects of maintaining voids of different shapes and sizes using two-dimensional lattice models. We study the propensity for conformations to form a void of specific shape, which is related to the entropic cost of void maintenance. We also study the location that voids of a specific shape and size tend to form, and the influence of compactness on the formation of such voids. As enumeration is infeasible for long chain polymer, a key development in this work is the design of a novel sequential Monte Carlo strategy for generating large number of sample conformations under very constraining restrictions. Our method is validated by comparing results obtained from sampling and from enumeration for short polymer chains. We succeeded in accurate estimation of entropic cost of void maintenance, with and without an increasing number of restrictive conditions, such as loops forming the wall of void with fixed length, with additionally fixed starting position in the sequence. Additionally, we have identified the key structural properties of voids that are important in determining the entropic cost of void formation. We have further developed a parametric model to predict quantitatively void entropy. Our model is highly effective, and these results indicate that voids representing functional sites can be used as an improved model for studying the evolution of protein functions and how protein function relates to protein stability.

  17. Toxicity of a metal(loid)-polluted agricultural soil to Enchytraeus crypticus changes under a global warming perspective: Variations in air temperature and soil moisture content.

    PubMed

    González-Alcaraz, M Nazaret; van Gestel, Cornelis A M

    2016-12-15

    This study aimed to assess how the current global warming perspective, with increasing air temperature (20°C vs. 25°C) and decreasing soil moisture content (50% vs. 30% of the soil water holding capacity, WHC), affected the toxicity of a metal(loid)-polluted agricultural soil to Enchytraeus crypticus. Enchytraeids were exposed for 21d to a dilution series of the agricultural soil with Lufa 2.2 control soil under four climate situations: 20°C+50% WHC (standard conditions), 20°C+30% WHC, 25°C+50% WHC, and 25°C+30% WHC. Survival, reproduction and bioaccumulation of As, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn were obtained as endpoints. Reproduction was more sensitive to both climate factors and metal(loid) pollution. High soil salinity (electrical conductivity~3dSm(-1)) and clay texture, even without the presence of high metal(loid) concentrations, affected enchytraeid performance especially at drier conditions (≥80% reduction in reproduction). The toxicity of the agricultural soil increased at drier conditions (10% reduction in EC10 and EC50 values for the effect on enchytraeid reproduction). Changes in enchytraeid performance were accompanied by changes in As, Fe, Mn, Pb and Zn bioaccumulation, with lower body concentrations at drier conditions probably due to greater competition with soluble salts in the case of Fe, Mn, Pb and Zn. This study shows that apart from high metal(loid) concentrations other soil properties (e.g. salinity and texture) may be partially responsible for the toxicity of metal(loid)-polluted soils to soil invertebrates, especially under changing climate conditions.

  18. Recovery and characterization of Balanites aegyptiaca Del. kernel proteins. Effect of defatting, air classification, wet sieving and aqueous ethanol treatment on solubility, digestibility, amino acid composition and sapogenin content.

    PubMed

    Mohamed, A M; Wolf, W; Spiess, W E

    2000-02-01

    In order to find alternative protein sources in African regions where protein deficiency in nutrition is prevailing, solubility, in-vitro digestibility, amino acid composition and chemical score of Balanites aegyptiaca Del. kernel proteins were investigated as a function of different processing steps including defatting, air classification, wet sieving and aqueous ethanol treatment. Air classification delivered a fine fraction of 58.1% of the total protein. Applying a wet sieving process, a protein concentrate of 72.9% protein content was achieved but the recovery was very low (35.6%). However, in case of isoelectric precipitation followed by aqueous ethanol treatment both protein content (78.2%) and recovery (53.7%) were high. Data concerning the chemical score revealed, that lysine content of the defatted kernel flour amounted to 74.2% of the recommended FAO/WHO standard level. In-vitro protein digestibility was found to be higher than of legume proteins. The digestible protein of the full fat flour, defatted flour, air classified and wet sieved fine fractions and protein concentrate were 91.9, 93.7, 82.0, 86.4 and 94.2%, respectively. The sapogenin content per 100 g protein of the investigated protein preparations was significantly lower (46% to 62%) than of the initial material (oilcake).

  19. Are we living near the center of a local void?

    NASA Astrophysics Data System (ADS)

    Cusin, Giulia; Pitrou, Cyril; Uzan, Jean-Philippe

    2017-03-01

    The properties of the cosmic microwave background (CMB) temperature and polarisation anisotropies measured by a static, off-centered observer located in a local spherically symmetric void, are described. In particular in this paper we compute, together with the standard 2-point angular correlation functions, the off-diagonal correlators, which are no more vanishing by symmetry. While the energy shift induced by the off-centered position of the observer can be suppressed by a proper choice of the observer velocity, a lensing-like effect on the CMB emission point remains. This latter effect is genuinely geometrical (e.g. non-degenerate with a boost) and reflects in the structure of the off-diagonal correlators. At lowest order in this effect, the temperature and polarisation correlation matrices have non-vanishing diagonal elements, as usual, and all the off-diagonal terms are excited. This particular signature of a local void model allows one, in principle, to disentangle geometrical effects from local kinematical ones in CMB observations.

  20. It Shall Not Return to Me Void: Teaching Religious Content to Individuals with Cognitive Disability

    ERIC Educational Resources Information Center

    Iguchi, Carolyn M.

    2010-01-01

    This research is an exploratory qualitative investigation into the challenges of teaching religious material to individuals with cognitive disabilities. The study setting was a single large evangelical Christian church known for excellence in ministry to individuals with disabilities and their families. The following issues were explored: (a)…

  1. Effect of Shear Deformation on Closure of a Central Void in Thin-Strip Rolling

    NASA Astrophysics Data System (ADS)

    Park, Jong-Jin

    2016-01-01

    Central voids or voids at the middle layer are often found in thin strips produced by twin-roll casting. These strips are in general so thin that they are unable to take a required reduction in thickness to close the voids. In the present investigation, equal-speed rolling and differential-speed rolling were compared to assess the effect of differential speed on closure of the voids by the rigid-plastic finite-element analysis. As a result, shear deformation developed in differential-speed rolling was found to reduce the reduction in thickness required for void closure. An increase in speed ratio, length of deformation zone, or friction coefficient at the interface expedited the progress in void closure. However, as the speed ratio exceeded thickness ratio, a portion of rolling power was dissipated extensively by excessive slip at the interface. Moreover, tensile stress developed which would cause cracks in the strip.

  2. Geometric and Chemical Composition Effects on Healing Kinetics of Voids in Mg-bearing Al Alloys

    NASA Astrophysics Data System (ADS)

    Song, Miao; Du, Kui; Wang, Chunyang; Wen, Shengping; Huang, Hui; Nie, Zuoren; Ye, Hengqiang

    2016-05-01

    The healing kinetics of nanometer-scale voids in Al-Mg-Er and Al-Mg-Zn-Er alloy systems were investigated with a combination of in situ transmission electron microscopy and electron tomography at different temperatures. Mg was observed completely healing the voids, which were then rejuvenated to the alloy composition with further aging, in the Al-Mg-Er alloy. On the contrary, Mg51Zn20 intermetallic compound was formed in voids in the Al-Mg-Zn-Er alloy, which leads to complete filling of the voids but not rejuvenation for the material. For voids with different geometrical aspects, different evolution processes were observed, which are related to the competition between bulk and surface diffusion of the alloys. For voids with a large size difference in their two ends, a viscous flow of surface atoms can be directly observed with in situ electron microscopy, when the size of one end becomes less than tens of nanometers.

  3. Method of simulating spherical voids for use as a radiographic standard

    DOEpatents

    Foster, Billy E.

    1977-01-01

    A method of simulating small spherical voids in metal is provided. The method entails drilling or etching a hemispherical depression of the desired diameter in each of two sections of metal, the sections being flat plates or different diameter cylinders. A carbon bead is placed in one of the hemispherical voids and is used as a guide to align the second hemispherical void with that in the other plate. The plates are then bonded together with epoxy, tape or similar material and the two aligned hemispheres form a sphere within the material; thus a void of a known size has been created. This type of void can be used to simulate a pore in the development of radiographic techniques of actual voids (porosity) in welds and serve as a radiographic standard.

  4. Directional diffusion and void formation at a Si (001) bonded wafer interface

    NASA Astrophysics Data System (ADS)

    Esser, R. H.; Hobart, K. D.; Kub, F. J.

    2002-08-01

    Low-temperature hydrophobic bonding is an enabling technology allowing the fabrication of device structures. Current research into improvement of hydrophobic bonding has focused on the elimination of thermally generated voids. It has been observed that a regular grid etched into the bonding interface can eliminate the thermally generated voids. By manipulation of patterns etched into the bond interface, it was possible to ascertain that the diffusion of interfacial gasses that form the thermally generated voids is enhanced along the <110> directions. This is shown by an analysis of the void density at various locations in relation to the etched trenches at the bonded interface. Void density between trenches is shown to be 12% of the void density near trenches but nto along a <110> direction.

  5. Glass composition and process for sealing void spaces in electrochemical devices

    DOEpatents

    Meinhardt, Kerry D [Richland, WA; Kirby, Brent W [Kennewick, WA

    2012-05-01

    A glass foaming material and method are disclosed for filling void spaces in electrochemical devices. The glass material includes a reagent that foams at a temperature above the softening point of the glass. Expansion of the glass fills void spaces including by-pass and tolerance channels of electrochemical devices. In addition, cassette to cassette seals can also be formed while channels and other void spaces are filled, reducing the number of processing steps needed.

  6. Mass flow rate measurements in gas-liquid flows by means of a venturi or orifice plate coupled to a void fraction sensor

    SciTech Connect

    Oliveira, Jorge Luiz Goes; Passos, Julio Cesar

    2009-01-15

    Two-phase flow measurements were carried out using a resistive void fraction meter coupled to a venturi or orifice plate. The measurement system used to estimate the liquid and gas mass flow rates was evaluated using an air-water experimental facility. Experiments included upward vertical and horizontal flow, annular, bubbly, churn and slug patterns, void fraction ranging from 2% to 85%, water flow rate up to 4000 kg/h, air flow rate up to 50 kg/h, and quality up to almost 10%. The fractional root mean square (RMS) deviation of the two-phase mass flow rate in upward vertical flow through a venturi plate is 6.8% using the correlation of Chisholm (D. Chisholm, Pressure gradients during the flow of incompressible two-phase mixtures through pipes, venturis and orifice plates, British Chemical Engineering 12 (9) (1967) 454-457). For the orifice plate, the RMS deviation of the vertical flow is 5.5% using the correlation of Zhang et al. (H.J. Zhang, W.T. Yue, Z.Y. Huang, Investigation of oil-air two-phase mass flow rate measurement using venturi and void fraction sensor, Journal of Zhejiang University Science 6A (6) (2005) 601-606). The results show that the flow direction has no significant influence on the meters in relation to the pressure drop in the experimental operation range. Quality and slip ratio analyses were also performed. The results show a mean slip ratio lower than 1.1, when bubbly and slug flow patterns are encountered for mean void fractions lower than 70%. (author)

  7. The effect of voids on the hardening of body-centered cubic Fe

    NASA Astrophysics Data System (ADS)

    Nakai, Ryosuke; Yabuuchi, Kiyohiro; Nogami, Shuhei; Hasegawa, Akira

    2016-04-01

    The mechanical properties of metals are affected by various types of defects. Hardening is usually described through the interaction between dislocations and obstacles, in the so-called line tension theory. The strength factor in the line tension theory represents the resistance of a defect against the dislocation motion. In order to understand hardening from the viewpoint of the microstructure, an accurate determination of the strength factor of different types of defects is essential. In the present study, the strength factor of voids in body-centered cubic (BCC) Fe was investigated by two different approaches: one based on the Orowan equation to link the measured hardness with the average size and density of voids, and the other involving direct observation of the interaction between dislocations and voids by transmission electron microscope (TEM). The strength factor of voids induced by ion irradiation estimated by the Orowan equation was 0.6, whereas the strength factor estimated by the direct TEM approach was 0.8. The difference in the strength factors measured by the two approaches is due to the positional relationship between dislocations and voids: the central region of a void is stronger than the tip. Moreover, the gliding plane and the direction of dislocation may also affect the strength factor of voids. This study determined the strength factor of voids in BCC Fe accurately, and suggested that the contribution of voids to the irradiation hardening is larger than that of dislocation loops and Cu-rich precipitates.

  8. Dislocation mechanism of void growth at twin boundary of nanotwinned nickel based on molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiu; Jiang, Shuyong; Zhu, Xiaoming; Zhao, Yanan

    2016-08-01

    Molecular dynamics simulation was performed to investigate dislocation mechanism of void growth at twin boundary (TB) of nanotwinned nickel. Simulation results show that the deformation of nanotwinned nickel containing a void at TB is dominated by the slip involving both leading and trailing partials, where the trailing partials are the dissociation products of stair-rod dislocations formed by the leading partials. The growth of a void at TB is attributed to the successive emission of the leading partials followed by trailing partials as well as the escape of these partial dislocations from the void surface.

  9. Study of void collapse leading to shock initiation and ignition in heterogeneous energetic material

    NASA Astrophysics Data System (ADS)

    Rai, Nirmal Kumar; Koundinyan, Sushilkumar Prabu; Udaykumar, H. S.

    2015-06-01

    In heterogeneous energetic materials like PBX, porosity plays an important role in shock initiation and ignition. This is because the collapse of voids leads to the formation of local high temperature regions termed as hot spots under the application of shock loading. The formation of hot spots can take place because of several mechanisms such as plastic deformation of voids, hydrodynamic impact on voids leading to the formation of high speed material jets etc. Once these hot spots are formed, they can lead to reaction and ignition in the explosive material. However, diffusive phenomenon like heat conduction can play an important role in shock initiation because depending on the size and intensity of void collapse hot spots, local ignition conditions can be smeared out. In the current work, void collapse leading to shock initiation and ignition in HMX has been studied using a massively parallel Eulerian code, SCIMITAR3D. The chemical kinetics of HMX decomposition and reaction has been modeled using the Henson-Smilowitz multi-step mechanism. Based on the current framework an ignition criterion has been established for single void collapse analysis for various shock strengths. Furthermore, the effects of void-void interactions have been analyzed demonstrating the important role of the combination of void fraction, reaction chemistry and heat conduction in determining the ignition threshold. This work has been funded from the AFRL-RWPC, Computational Mechanics Branch, Eglin AFB, Program Manager: Dr. Martin Schmidt.

  10. Void-Filled SRTM Digital Elevation Model of Afghanistan

    USGS Publications Warehouse

    Chirico, Peter G.; Barrios, Boris

    2005-01-01

    EXPLANATION The purpose of this data set is to provide a single consistent elevation model to be used for national scale mapping, GIS, remote sensing applications, and natural resource assessments for Afghanistan's reconstruction. For 11 days in February of 2000, the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency ian Space Agency (ASI) flew X-band and C-band radar interferometry onboard the Space Shuttle Endeavor. The mission covered the Earth between 60?N and 57?S and will provide interferometric digital elevation models (DEMs) of approximately 80% of the Earth's land mass when processing is complete. The radar-pointing angle was approximately 55? at scene center. Ascending and descending orbital passes generated multiple interferometric data scenes for nearly all areas. Up to eight passes of data were merged to form the final processed Shuttle Radar Topography Mission (SRTM) DEMs. The effect of merging scenes averages elevation values recorded in coincident scenes and reduces, but does not completely eliminate, the amount of area with layover and terrain shadow effects. The most significant form of data processing for the Afghanistan DEM was gap-filling areas where the SRTM data contained a data void. These void areas are as a result of radar shadow, layover, standing water, and other effects of terrain as well as technical radar interferometry phase unwrapping issues. To fill these gaps, topographic contours were digitized from 1:200,000 - scale Soviet General Staff Topographic Maps which date from the middle to late 1980's. Digital contours were gridded to form elevation models for void areas and subsequently were merged with the SRTM data through GIS and image processing techniques. The data contained in this publication includes SRTM DEM quadrangles projected and clipped in geographic coordinates for the entire country. An index of all available SRTM DEM quadrangles is displayed here: Index_Geo_DD.pdf. Also

  11. Voids Strengthen Rock Friction at Subseismic Slip Velocity

    NASA Astrophysics Data System (ADS)

    Fukuyama, E.; Yamashita, F.; Mizoguchi, K.

    2011-12-01

    To investigate the origin of instabilities during the sub-seismic sliding velocity of rock-rock friction experiments as seen in Mizoguchi and Fukuyama (2010, Int. J. Rock Mech. Min. Sci.), we measured the elastic waves transmitted through the sliding interfaces during slipping using the high-velocity rotary-shear friction apparatus at NIED. Experiments were done using the Indian gabbro samples under the normal stress of 3MPa and slip velocity of either 0.006m/s or 0.06m/s. In this normal stress and slip velocity range, steady-state friction fluctuates between 0.4 and 0.6. We found that the amplitude of transmitted waves changes as a function of coefficient of friction. Since we used the piezoelectric device at both source and receiver, whose resonance frequency is 0.5MHz applying 0.5MHz half cycle sine pulse as input signal and the scale of the heterogeneity (a) is roughly estimated at 10-6m from the thickness of the slip zone, ak becomes much smaller than one, where k being wavenumber (~500m-1). It is already well-known that when ak <<1, the transmitted wave attenuates but its propagation velocity does not change (e.g. Yamashita, 1990, PAGEOPH). In the present experiments, we observed the decrease in amplitude of transmitted waves when sliding friction is high and its increase when friction is low. Taking into account that the variation of amplitudes reflects the variation of characteristic size of voids (i.e., a), we can interpret the observed data that high friction is caused by the creation of large-sized voids due to the wearing process to generate gouge particles (peeled of from the host rock wall) and low friction state is achieved due the decrease of it by grain size reduction caused by granular processes. High friction state with large-sized voids can be interpreted as the creation of stress chain (e.g. Liu et al., 1995, Science) and due to the collapse of the pores around the gouge particles, the friction decreases. Therefore, in the present experiments

  12. Influence of CsCl addition on the nanostructured voids and optical properties of 80GeS2-20Ga2S3 glasses

    NASA Astrophysics Data System (ADS)

    Klym, H.; Ingram, A.; Shpotyuk, O.; Karbovnyk, I.

    2016-09-01

    The influence of CsCl content on the void evolution in (80GeS2-20Ga2S3)100-x(CsCl)x, x = 0; 5; 10; 15, chalcogenide glasses and changes of the optical response of these glasses due to CsCl addition are investigated. It is shown that structural agglomeration of voids occurs at addition and increasing of CsCl amount in base glasses. Supersaturation of GeS2-Ga2S3-CsCl glasses by CsCl results in the contraction of void volumes in (80GeS2-20Ga2S3)85(CsCl)15. By applying positron-positronium decomposition algorithm it was established that CsCl not only transforms voids in glass, but also forms new positron-trapping sites in Ge-Ga-S glassy matrix. Therefore, CsCl addition results in the shift of fundamental transmission edge in the visible region. It is shown that doping by larger concentrations of CsCl may lead to "supersaturation" of base glasses and that adding 10 mol% of CsCl is apparently an optimal doping level in view of further modification of glasses with rare-earth ions.

  13. Close Resemblance Between Local Summer Insolation, O2/N2 and Total Air Content from the Dome Fuji Ice Core, Antarctica

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Nakazawa, T.; Aoki, S.; Fujii, Y.; Watanabe, O.; Severinghaus, J. P.

    2004-12-01

    O2/N2 ratio from ice cores has shown depleted values compared to the atmosphere due to selective exclusion of O2 during bubble formation at the base of firn. The long record from the Vostok ice core revealed that O2/N2 ratio records the local summer insolation. Insolation may affect physical properties of the firn near the surface, which later determines how much O2/N2 is fractionated the during bubble close-off process. We present here a supportive record of O2/N2 ratio for the last 340 kyr along the Dome Fuji ice core, Antarctica, which shows variations similar to the summer insolation at 77° S. Moreover, the variation of total air content (TAC) in the Dome Fuji core resembles that of O2/N2. High TAC and high O2/N2 ratio appear at times of low summer insolation. Since the TAC variation is too large to be explained by the elevation change at the Dome Fuji site in the past, a possible cause is variation of the so-called ``lock-in zone'' thickness on the orders of several meters. The lock-in zone is a region 0-10 m thick at the bottom of firn where horizontal impermeable layers prevent vertical gas mixing. At times of low insolation, the firn would retain inhomogeneities such as wind crusts and high-density layers. These small-scale inhomogeneities do not affect bulk density very much but may help trap the gases at a lower bulk density (and higher porosity and thus TAC) through formation of a thicker lock-in zone than in times of high insolation. High insolation would homogenize the firn structure through recrystallization. O2/N2 ratio would be less depleted if there is a lock-in zone within the total close-off zone, because O2 molecules once excluded from bubbles would eventually be re-trapped in the ice in the lock-in zone.

  14. Managing voids of Si anodes in lithium ion batteries.

    PubMed

    Li, Xianglong; Zhi, Linjie

    2013-10-07

    The implementation of silicon (Si) in practical lithium ion battery electrodes has been hindered due to its large volume change and consequent structural and interfacial instabilities. Coating nanostructured Si with a second phase (e.g., carbon (C)) represents a very promising strategy for dealing with these critical issues facing Si-based electrodes. In this review article, we will outline recent advances in coating Si with engineered C matrices. By exemplifying hollow core-shell, core-hollow shell, and core-shell structured Si-C hybrid nanomaterials, we aim to highlight the importance of managing voids in designing such Si-C hybrid electrodes, and provide some scientific insights into the development of advanced Si-based anodes for next-generation lithium ion batteries.

  15. Mechanistic model for void distribution in flashing flow

    SciTech Connect

    Riznic, J.; Ishii, M.; Afgan, N.

    1987-01-01

    A problem of discharging of an initially subcooled liquid from a high pressure condition into a low pressure environment is quite important in several industrial systems such as nuclear reactors and chemical reactors. A new model for the flashing process is proposed here based on the wall nucleation theory, bubble growth model and drift-flux bubble transport model. In order to calculate the bubble number density, the bubble number transport equation with a distributed source from the wall nucleation sites is used. The model predictions in terms of the void fraction are compared to Moby Dick and BNL experimental data. It shows that satisfactory agreements could be obtained from the present model without any floating parameter to be adjusted with data. This result indicates that, at least for the experimental conditions considered here, the mechanistic prediction of the flashing phenomenon is possible based on the present wall nucleation based model. 43 refs., 4 figs.

  16. Observational Search for Negative Matter in Intergalactic Voids

    NASA Technical Reports Server (NTRS)

    Forward, Robert L.

    1999-01-01

    Negative matter is a hypothetical form of matter with negative rest mass, inertial mass, and gravitational mass. It is not antimatter. If negative matter could be collected in macroscopic amounts, its negative inertial property could be used to make an continuously operating propulsion system which requires neither energy nor reaction mass, yet still violates no laws of physics. Negative matter has never been observed, but its existence is not forbidden by the laws of physics. We propose that NASA support an extension to an ongoing astrophysical observational effort by da Costa, et al. (1996) which could possibly determine whether or not negative matter exists in the well-documented but little-understood intergalactic voids.

  17. GPR surveying of transport infrastructures and buildings; underground utility and void sensing - ongoing activities in Working Group 2 of COST Action TU1208

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Plati, Christina; Derobert, Xavier

    2015-04-01

    areas.' Project 2.4 focuses on the development of 'Innovative procedures for effective GPR inspection of construction materials and structures.' The WG2 also includes Project 2.5 on the 'Determination, by using GPR, of the volumetric water content in structures, sub-structures, foundations and soil,' this is a topic of great interest in civil engineering, as water infiltration is often a relevant cause of degradation of structures, such as roads of bridges, and of rebar corrosion. During the first year of the Action, information was collected and shared about state-of-the-art, ongoing studies, problems and future research needs, in the topics covered by the five above-mentioned Projects [1-3]. Based on the experience and knowledge gained from the in-depth review work carried out by WG2, several case studies were then conducted; they were presented during the Second General Meeting and the GPR 2014 conference [5, 6]. Furthermore, the extension of GPR application to railways track ballast assessment was demonstrated [7]. The WG2 identified reference test-sites, suitable to compare inspection procedures or to test GPR equipment. The IFSTTAR geophysical test site is an open-air laboratory including a large and deep area, filled with various materials arranged in horisontal compacted slices, separated by vertical interfaces and water-tighted in surface; several objects as pipes, polystyrene hollows, boulders and masonry are embedded in the field [4]. The IFSTTAR full-scale APT facility is an outdoor circular carousel dedicated to full-scale pavement experiments, consisting of a central tower and four long arms equipped with wheels, running on a circular test track [4]. Furthermore, the WG2 is building a database of available experimental results, which are at the disposal of WG3 Members to test their electromagnetic modeling/inversion/data-processing methods. Another interesting and promising WG2 initiative that has to be mentioned is the development of a Catalogue of

  18. Computation studies of vacancy and void defects interactions in polycrystalline UO2

    NASA Astrophysics Data System (ADS)

    Chiang, Tsu-Wu

    This dissertation uses atomic-level simulations to analyze void nucleation from isolated vacancies, the interactions of voids with a grain boundary (GB), and the evolution of void nucleation on a GB in UO2, the ubiquitous fuel material for light water reactors. The atomic-level mechanisms and the energetics associated with these processes are characterized. Simulations are performed at high temperature to accelerate the dynamical processes. Evaluation of the energetics shows that isolated defects, voids and GB interact through elastic and electrostatic forces. Void growth mechanisms, Ostwald ripening and coalescence are identified and characterized. A kinetic evolution map of void growth is developed. GB migration towards to the void is predicted to take place. Both GB pinning to the void and void dissolution at the GB take place. Vacancy accumulation at GBs is observed both when vacancies migrate into a GB and when a GB migrates to void/vacancies. The profile of the vacancy-GB segregation energy explains the GB-vacancies attraction behavior. The GB-void complex at various vacancy densities is also discussed to elucidate the GB nucleation evolution from dissolution, nucleation, and interconnection. In addition to UO2, this dissertation also addresses oxidation of Zr. Density functional theory calculations are used to analyze the energy barriers for oxygen migration into the basal and prismatic surfaces of zirconium. The migration energy barriers between each octahedral site and tetrahedral site in the basal surface, prism surface, and bulk are determined. The lowest penetration paths of these two surface are also identified and a possible mechanism for the anisotropy in the oxidation of Zr surfaces is identified.

  19. Rayleigh-wave diffractions due to a void in the layered half space

    USGS Publications Warehouse

    Xia, J.; Xu, Y.; Miller, R.D.; Nyquist, J.E.

    2006-01-01

    Void detection is challenging due to the complexity of near-surface materials and the limited resolution of geophysical methods. Although multichannel, high-frequency, surface-wave techniques can provide reliable shear (S)-wave velocities in different geological settings, they are not suitable for detecting voids directly based on anomalies of the S-wave velocity because of limitations on the resolution of S-wave velocity profiles inverted from surface-wave phase velocities. Xia et al. (2006a) derived a Rayleigh-wave diffraction traveltime equation due to a void in the homogeneous half space. Encouraging results of directly detecting a void from Rayleigh-wave diffractions were presented (Xia et al., 2006a). In this paper we used four two-dimensional square voids in the layered half space to demonstrate the feasibility of detecting a void with Rayleigh-wave diffractions. Rayleigh-wave diffractions were recognizable for all these models after removing direct surface waves by F-K filtering. We evaluate the feasibility of applying the Rayleigh-wave diffraction traveltime equation to a void in the layered earth model. The phase velocity of diffracted Rayleigh waves is predominately determined by surrounding materials of a void. The modeling results demonstrate that the Rayleigh-wave diffraction traveltime equation due to a void in the homogeneous half space can be applied to the case of a void in the layered half space. In practice, only two diffraction times are necessary to define the depth to the top of a void and the average velocity of diffracted Rayleigh waves. ?? 2005 Society of Exploration Geophysicists.

  20. Log-Normal Distribution of Cosmic Voids in Simulations and Mocks

    NASA Astrophysics Data System (ADS)

    Russell, E.; Pycke, J.-R.

    2017-01-01

    Following up on previous studies, we complete here a full analysis of the void size distributions of the Cosmic Void Catalog based on three different simulation and mock catalogs: dark matter (DM), haloes, and galaxies. Based on this analysis, we attempt to answer two questions: Is a three-parameter log-normal distribution a good candidate to satisfy the void size distributions obtained from different types of environments? Is there a direct relation between the shape parameters of the void size distribution and the environmental effects? In an attempt to answer these questions, we find here that all void size distributions of these data samples satisfy the three-parameter log-normal distribution whether the environment is dominated by DM, haloes, or galaxies. In addition, the shape parameters of the three-parameter log-normal void size distribution seem highly affected by environment, particularly existing substructures. Therefore, we show two quantitative relations given by linear equations between the skewness and the maximum tree depth, and between the variance of the void size distribution and the maximum tree depth, directly from the simulated data. In addition to this, we find that the percentage of voids with nonzero central density in the data sets has a critical importance. If the number of voids with nonzero central density reaches ≥3.84% in a simulation/mock sample, then a second population is observed in the void size distributions. This second population emerges as a second peak in the log-normal void size distribution at larger radius.

  1. Void probability as a function of the void's shape and scale-invariant models. [in studies of spacial galactic distribution

    NASA Technical Reports Server (NTRS)

    Elizalde, E.; Gaztanaga, E.

    1992-01-01

    The dependence of counts in cells on the shape of the cell for the large scale galaxy distribution is studied. A very concrete prediction can be done concerning the void distribution for scale invariant models. The prediction is tested on a sample of the CfA catalog, and good agreement is found. It is observed that the probability of a cell to be occupied is bigger for some elongated cells. A phenomenological scale invariant model for the observed distribution of the counts in cells, an extension of the negative binomial distribution, is presented in order to illustrate how this dependence can be quantitatively determined. An original, intuitive derivation of this model is presented.

  2. Influence of annealing conditions on the formation of regular lattices of voids and Ge quantum dots in an amorphous alumina matrix.

    PubMed

    Pinto, S R C; Buljan, M; Marques, L; Martín-Sánchez, J; Conde', O; Chahboun, A; Ramos, A R; Barradas, N P; Alves, E; Bernstorff, S; Grenzer, J; Mücklich, A; Ramos, M M D; Gomes, M J M

    2012-10-12

    In this work, the influence of air pressure during the annealing of Ge quantum dot (QD) lattices embedded in an amorphous Al(2)O(3) matrix on the structural, morphological and compositional properties of the film is studied. The formation of a regularly ordered void lattice after performing a thermal annealing process is explored. Our results show that both the Ge desorption from the film and the regular ordering of the QDs are very sensitive to the annealing parameters. The conditions for the formation of a void lattice, a crystalline Ge QD lattice and a disordered QD lattice are presented. The observed effects are explained in terms of oxygen interaction with the Ge present in the film.

  3. VizieR Online Data Catalog: VIPERS. Searching for cosmic voids (Micheletti+, 2014)

    NASA Astrophysics Data System (ADS)

    Micheletti, D.; Hawken, A.; Iovino, A. J.; Granett, B.; Bolzonella, M.; Cappi, A.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bottini, D.; Branchini, E.; Coupon, J.; Cucciati, O.; Davidzon, I.; de Lucia, G.; de la Torre, S.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Guzzo, L.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fevre, O.; Maccagni, D.; Malek, K.; Marulli, F.; McCracken, H. J.; Polletta, M.; Pollo, A.; Schimd, C.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moutard, T.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Zamorani, G.

    2014-09-01

    File voidtable.dat lists the catalogue of maximal spheres detected in VIPERS samples, divided in groups corresponding to individual voids. The spheres have been associated with larger under-densities using the percolation method, thus we associate each sphere with a void index indicating larger empty regions. The identification number (ID) of each maximal sphere is composed of: the VIPERS field to which the maximal sphere belongs (W1 or W4); a void index indicating to which void the sphere belongs (VVVV); a sphere index SSSS indicating the size rank of the sphere relative to other maximal spheres within the same void. The complete ID has the form Wx.VVVV.SSSS. For each maximal sphere of our catalogue we provide: its ID; its comoving radius in Mpc (Ωm=0.27, ΩΛ=0.73 and H0=70km/s/Mpc); the right ascension, declination, and redshift of the sphere's centre; a p-value giving the detection significance with respect to a Poisson distribution. Voids are sorted in ascending redshift order, with the redshift associated with each void being that of its largest sphere. Spheres inside each void are sorted in decreasing radius order. (1 data file).

  4. 42 CFR 457.216 - Treatment of uncashed or canceled (voided) CHIP checks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... GRANTS TO STATES General Administration-Reviews and Audits; Withholding for Failure to Comply; Deferral... section— Canceled (voided) check means an CHIP check issued by a State or fiscal agent that prior to its being cashed is canceled (voided) by the State or fiscal agent, thus preventing disbursement of...

  5. Atomistic insights into dislocation-based mechanisms of void growth and coalescence

    NASA Astrophysics Data System (ADS)

    Mi, Changwen; Buttry, Daniel A.; Sharma, Pradeep; Kouris, Demitris A.

    2011-09-01

    One of the low-temperature failure mechanisms in ductile metallic alloys is the growth of voids and their coalescence. In the present work we attempt to obtain atomistic insights into the mechanisms underpinning cavitation in a representative metal, namely Aluminum. Often the pre-existing voids in metallic alloys such as Al have complex shapes (e.g. corrosion pits) and the defromation/damage mechanisms exhibit a rich size-dependent behavior across various material length scales. We focus on these two issues in this paper through large-scale calculations on specimens of sizes ranging from 18 thousand to 1.08 million atoms. In addition to the elucidation of the dislocation propagation based void growth mechanism we highlight the observed length scale effect reflected in the effective stress-strain response, stress triaxiality and void fraction evolution. Furthermore, as expected, the conventionally used Gurson's model fails to capture the observed size-effects calling for a mechanistic modification that incorporates the mechanisms observed in our (and other researchers') simulation. Finally, in our multi-void simulations, we find that, the splitting of a big void into a distribution of small ones increases the load-carrying capacity of specimens. However, no obvious dependence of the void fraction evolution on void coalescence is observed.

  6. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  7. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  8. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  9. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  10. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  11. A molecular dynamics study of void initiation and growth in monocrystalline and nanocrystalline copper

    NASA Astrophysics Data System (ADS)

    Traiviratana, Sirirat

    MD simulations in monocrystalline and nanocrystalline copper were carried out with LAMMPS to reveal void growth mechanisms. The specimens were subjected to both tensile uniaxial and hydrostatic strains; the results confirm that the emission of (shear) loops is the primary mechanism of void growth. The expansion of the loops and their cross slip leads to the severely work hardened layer surrounding a growing void. Calculations were carried out on voids with different sizes, and a size dependence of the stress response to emitted dislocations was observed, in disagreement with the Gurson model [1] which is scale independent. The growth of voids simulated by MD is compared with the Cocks-Ashby constitutive model and significant agreement is found. The density of geometrically-necessary dislocations as a function of void size is calculated based on the emission of shear loops and their outward propagation. Calculations were also carried out for a void at the interface between two grains sharing a tilt boundary. The results show similar dislocation behaviors. A code that uses Voronoi tessellation for constructing nanocrystalline structures was developed and used to prepare the structures for simulations. Nanocrystal simulations reveal grain sliding and grain rotation as the nanocrystal deformed. Voids were nucleated at grain junctions and grew to coalescence as dislocations accommodated the material transfer. A code that can be used during post-processing to extract useful dislocation information from MD simulation data was partially developed and proved the feasibility of automatically analyzing dislocations.

  12. In search of empty places: Voids in the distribution of galaxies

    NASA Astrophysics Data System (ADS)

    Bucklein, Brian K.

    2010-12-01

    We investigate several techniques to identify voids in the galaxy distribution of matter in the universe. We utilize galaxy number counts as a function of apparent magnitude and Wolf plots to search a two- or three-dimensional data set in a pencil-beam fashion to locate voids within the field of view. The technique is able to distinguish between voids that represent simply a decrease in density as well as those that show a build up of galaxies on the front or back side of the void. This method turns out to be primarily useable only at relatively short range (out to about 200 Mpc). Beyond this distance, the characteristics indicating a void become increasingly difficult to separate from the statistical background noise. We apply the technique to a very simplified model as well as to the Millennium Run dark matter simulation. We then compare results with those obtained on the Sloan Digital Sky Survey. We also created the Watershed Void Examiner (WaVE) which treats densities in a fashion similar to elevation on a topographical map, and then we allow the "terrain" to flood. The flooded low-lying regions are identified as voids, which are allowed to grow and merge as the level of flooding becomes higher (the overdensity threshold increases). Void statistics can be calculated for each void. We also determine that within the Millennium Run semi-analytic galaxy catalog, the walls that separate the voids are permeable at a scale of 4 Mpc. For each resolution that we tested, there existed a characteristic density at which the walls could be penetrated, allowing a single void to grow to dominate the volume. With WaVE, we are able to get comparable results to those previously published, but often with fewer choices of parameters that could bias the results. We are also able to determine the the density at which the number of voids peaks for different resolutions as well as the expected number of void galaxies. The number of void galaxies is amazingly consistent at an

  13. Spatial and dynamical properties of voids in a Λ cold dark matter universe

    NASA Astrophysics Data System (ADS)

    Padilla, N. D.; Ceccarelli, L.; Lambas, D. G.

    2005-11-01

    We study the statistical properties of voids in the distribution of mass, dark-matter haloes and galaxies (BJ < -16) in a Λ cold dark matter (ΛCDM)numerical simulation populated with galaxies using a semi-analytic galaxy formation model (GALFORM, Cole et al.). We find that the properties of voids selected from GALFORM galaxies are compatible with those of voids identified from a population of haloes with mass M > 1011.5h-1Msolar, similar to the median halo mass, Mmed= 1011.3h-1Msolar. We also find that the number density of galaxy- and halo-defined voids can be up to two orders of magnitude higher than mass-defined voids for large void radii, however, we observe that this difference is reduced to about half an order of magnitude when the positions are considered in redshift space. As expected, there are outflow velocities that show their maximum at larger void-centric distances for larger voids. We find a linear relation for the maximum outflow velocity, vmax=v0rvoid. The void-centric distance where this maximum occurs follows a suitable power-law fit of the form log(dvmax)=(rvoid/A)B. At sufficiently large distances, we find mild infall motions on to the subdense regions. The galaxy velocity field around galaxy-defined voids is consistent with the results of haloes with masses above the median, showing milder outflows than the mass around mass-defined voids. We find that a similar analysis in redshift space would make both outflows and infalls appear with a lower amplitude. We also find that the velocity dispersion of galaxies and haloes is larger in the direction parallel to the void walls by ~=10-20 per cent. Given that voids are by definition subdense regions, the cross-correlation function between galaxy-defined voids and galaxies is close to ξ=-1 out to separations comparable to the void size, and at larger separations the correlation function level increases, approaching the values of the auto-correlation function of galaxies. The cross

  14. A numerical study of void nucleation and growth in a flip chip assembly process

    NASA Astrophysics Data System (ADS)

    Lee, Sangil; Zhou, Hao Min; Baldwin, Daniel F.

    2010-09-01

    In this study, we develop mathematical models and numerical simulations of void nucleation and growth induced by the chemical reaction in the flip chip package assembly process using a no-flow underfill. During the thermal assembly process, the underfill chemically reacts to the oxidation of solders I/O on the chip, achieving interconnection between chip and substrate. The chemical reaction causes a large number of voids in the thermal reflow process. The voids have been considered as a critical defect, reducing the life of the thermal reliability. This study investigates the mechanism of void nucleation and growth based on classical bubble nucleation theory and bubble dynamics, respectively. This knowledge can provide a theoretical foundation to achieve a void-free assembly process and high reliability performance.

  15. The Irradiation Effect of a Simultaneous Laser and Electron Dual-beam on Void Formation

    PubMed Central

    Yang, Zhanbing; Watanabe, Seiichi; Kato, Takahiko

    2013-01-01

    Randomly distributed lattice point defects such as supersaturated vacancies (SVs) and Frenkel-pairs (FPs, an interstitial and a vacancy) can be simultaneously introduced into the crystal by energetic beam irradiation in outer space and/or nuclear reactors, but their behavior has not been fully understood. Using a high-voltage electron microscope equipped with a laser (laser-HVEM), we show the striking effects of simultaneous laser-electron (photon-electron) dual-beam irradiation on void formation. Our results reveal that during laser-electron sequential irradiation, pre-laser irradiation enhanced void nucleation and subsequent electron irradiation enhanced void growth. However, the laser-electron dual-beam irradiation was analyzed to depress void swelling remarkably because the recombination of SVs and interstitials was enhanced. The results provide insight into the mechanism underlying the dual-beam radiation-induced depression of void swelling in solids. PMID:23383371

  16. Spatially extended void-free dusty plasmas in a laboratory radio-frequency discharge

    SciTech Connect

    Schmidt, C.; Arp, O.; Piel, A.

    2011-01-15

    Laboratory experiments with thermophoretic levitation of dust are described that aim at the closure of a central dust-free void region. A careful study of the void structure as a function of the discharge and levitation parameters leads to the discovery of an extended parameter region where stable void-free equilibria are found. The void closure is effected by a novel mechanism that involves a self-organized change in the discharge topology, in which the dust cloud becomes surrounded by a toroidal region of plasma production. In this geometry ions are found to stream radially inwards instead of outwards as in clouds with a central void. This change in ion flow is proved by a reversal of the propagation direction of dust-density waves.

  17. Thermal analysis of void cavity for heat pipe receiver under microgravity

    NASA Astrophysics Data System (ADS)

    Gui, Xiaohong; Song, Xiange; Nie, Baisheng

    2017-04-01

    Based on theoretical analysis of PCM (Phase Change Material) solidification process, the model of improved void cavity distribution tending to high temperature region is established. Numerical results are compared with NASA (National Aeronautics and Space Administration) results. Analysis results show that the outer wall temperature, the melting ratio of PCM and the temperature gradient of PCM canister, have great difference in different void cavity distribution. The form of void distribution has a great effect on the process of phase change. Based on simulation results under the model of improved void cavity distribution, phase change heat transfer process in thermal storage container is analyzed. The main goal of the improved designing for PCM canister is to take measures in reducing the concentration distribution of void cavity by adding some foam metal into phase change material.

  18. Reliability of void detection in structural ceramics using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Klima, S. J.; Kiser, J. D.; Baaklini, G. Y.

    1985-01-01

    The reliability of scanning laser acoustic microscopy (SLAM) for detecting surface voids in structural ceramic test specimens was statistically evaluated. Specimens of sintered silicon nitride and sintered silicon carbide, seeded with surface voids, were examined by SLAM at an ultrasonic frequency of 100 MHz in the as fired condition and after surface polishing. It was observed that polishing substantially increased void detectability. Voids as small as 100 micrometers in diameter were detected in polished specimens with 0.90 probability at a 0.95 confidence level. In addition, inspection times were reduced up to a factor of 10 after polishing. The applicability of the SLAM technique for detection of naturally occurring flaws of similar dimensions to the seeded voids is discussed. A FORTRAN program listing is given for calculating and plotting flaw detection statistics.

  19. An initial study of void formation during solidification of aluminum in normal and reduced-gravity

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis P.; Foerster, George; Gotti, Daniel J.; Neumann, Eric S.; Johnston, J. C.; De Witt, Kenneth J.

    1992-01-01

    Void formation due to volumetric shrinkage during aluminum solidification was observed in real time using a radiographic viewing system in normal and reduced gravity. An end chill directional solidification furnace with water quench was developed to solidify aluminum samples during the approximately 16 seconds of reduced gravity (+/- 0.02g) achieved by flying an aircraft through a parabolic trajectory. Void formation was recorded for two cases: first a nonwetting system; and second, a wetting system where wetting occurs between the aluminum and crucible lid. The void formation in the nonwetting case is similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible. In the wetting case in reduced gravity, surface tension causes two voids to form in the top corners of the crucible, but in normal gravity only one large voids forms across the top.

  20. A statistical mechanics model to predict electromigration induced damage and void growth in solder interconnects

    NASA Astrophysics Data System (ADS)

    Wang, Yuexing; Yao, Yao; Keer, Leon M.

    2017-02-01

    Electromigration is an irreversible mass diffusion process with damage accumulation in microelectronic materials and components under high current density. Based on experimental observations, cotton type voids dominate the electromigration damage accumulation prior to cracking in the solder interconnect. To clarify the damage evolution process corresponding to cotton type void growth, a statistical model is proposed to predict the stochastic characteristic of void growth under high current density. An analytical solution of the cotton type void volume growth over time is obtained. The synchronous electromigration induced damage accumulation is predicted by combining the statistical void growth and the entropy increment. The electromigration induced damage evolution in solder joints is developed and applied to verify the tensile strength deterioration of solder joints due to electromigration. The predictions agree well with the experimental results.

  1. Exploring Cosmic Voids with GALEX: Stellar Populations and Primordial Jeans Mass Objects

    NASA Astrophysics Data System (ADS)

    Gregg, Michael

    This proposed research program will revolutionize the study of cosmic voids and their inhabitant galaxy populations. By combining archival GALEX photometry with SDSS data for thousands of galaxies in hundreds of voids, we will be able to characterize voids, void galaxies, and the formation and evolution of galaxies in the lowest density environments of the Universe. In addition, we propose to use the joint GALEX-SDSS database to search in several of the nearest cosmic voids for the original building blocks of galaxy formation: surviving Jeans mass primordial objects which formed right after recombination during the earliest stages of structure formation in the Universe. Our program will first characterize known void galaxies in the UV using the extensive GALEX NUV and FUV imaging archives. Adding GALEX UV photometry to SDSS optical enables estimating star formation rates and also separating stars from unresolved galaxies. Based on this effort, we will look for trends in galaxy properties with location within a void and with global void properties such as size and underdensity. We are particularly interested in identifying and characterizing the early type galaxy population in voids. While most void galaxies are blue, there do exist ellipticals in voids; comparison with ellipticals in denser regions will inform elliptical galaxy models in new ways, and teach us about the oldest and earliest stages of galaxy formation in voids. Early type galaxies are easy to miss in void redshift surveys, even with the comprehensive nature of SDSS, because most have relied on emission line searches or infrared excess. Our approach is fundamentally different, using an enhanced GALEX UV-optical selection technique which we have developed specifically for this work. A search for early type objects is necessary to fully understand void galaxy populations. In parallel, we will use our UV-optical selection technique to search for primordial Jeans mass sized objects in the nearest voids

  2. Probability of detection of internal voids in structural ceramics using microfocus radiography

    NASA Technical Reports Server (NTRS)

    Baaklini, G. Y.; Roth, D. J.

    1985-01-01

    The reliability of microfocus x-radiography for detecting subsurface voids in structural ceramic test specimens was statistically evaluated. The microfocus system was operated in the projection mode using low X-ray photon energies (20 keV) and a 10 micro m focal spot. The statistics were developed for implanted subsurface voids in green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously-obtained statistics for implanted surface voids in similar specimens. Problems associated with void implantation are discussed. Statistical results are given as probability-of-detection curves at a 95 percent confidence level for voids ranging in size from 20 to 528 micro m in diameter.

  3. The lensing and temperature imprints of voids on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Cai, Yan-Chuan; Neyrinck, Mark; Mao, Qingqing; Peacock, John A.; Szapudi, Istvan; Berlind, Andreas A.

    2017-04-01

    We have searched for the signature of cosmic voids in the cosmic microwave background (CMB), in both the Planck temperature and lensing-convergence maps; voids should give decrements in both. We use ZOBOV voids from the Data Release 12 Sloan Digital Sky Survey CMASS galaxy sample. We base our analysis on N-body simulations, to avoid a posteriori bias. For the first time, we detect the signature of voids in CMB lensing: the significance is 3.2σ, close to Λ cold dark matter (ΛCDM) in both amplitude and projected density-profile shape. A temperature dip is also seen, at modest significance (2.3σ), with an amplitude about six times the prediction. This temperature signal is induced mostly by voids with radii between 100 and 150 h-1 Mpc, while the lensing signal is mostly contributed by smaller voids - as expected; lensing relates directly to density, while integrated Sachs-Wolfe effect (ISW) depends on gravitational potential. The void abundance in observations and simulations agree as well. We also repeated the analysis excluding lower significance voids: no lensing signal is detected with an upper limit of about twice the ΛCDM prediction. But the mean temperature decrement now becomes non-zero at the 3.7σ level (similar to that found by Granett et al.), with an amplitude about 20 times the prediction. However, the observed dependence of temperature on void size is in poor agreement with simulations, whereas the lensing results are consistent with ΛCDM theory. Thus, the overall tension between theory and observations does not favour non-standard theories of gravity, despite the hints of an enhanced amplitude for the ISW effect from voids.

  4. Heat transfer, pressure drop and void fraction in two- phase, two-component flow in a vertical tube

    NASA Astrophysics Data System (ADS)

    Sujumnong, Manit

    1998-09-01

    There are very few data existing in two-phase, two- component flow where heat transfer, pressure drop and void fraction have all been measured under the same conditions. Such data are very valuable for two-phase heat-transfer model development and for testing existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and/or void fraction. An experiment was performed which adds markedly to the available data of the type described in terms of the range of gas and liquid flow rates and liquid Prandtl number. Heat transfer and pressure drop measurements were taken in a vertical 11.68-mm i.d. tube for two-phase (gas-liquid) flows covering a wide range of conditions. Mean void fraction measurements were taken, using quick- closing valves, in a 12.7-mm i.d. tube matching very closely pressures, temperatures, gas-phase superficial velocities and liquid-phase superficial velocities to those used in the heat-transfer and pressure-drop experiments. The gas phase was air while water and two aqueous solutions of glycerine (59 and 82% by mass) were used as the liquid phase. In the two-phase experiments the liquid Prandtl number varied from 6 to 766, the superficial liquid velocity from 0.05 to 8.5 m/s, and the superficial gas velocity from 0.02 to 119 m/s. The measured two-phase heat-transfer coefficients varied by a factor of approximately 1000, the two-phase frictional pressure drop ranged from small negative values (in slug flow) to 93 kPa and the void fraction ranged from 0.01 to 0.99; the flow patterns observed included bubble, slug, churn, annular, froth, the various transitions and annular-mist. Existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and/or void fraction were: tested against the present data for mean heat-transfer coefficients. It was found that the methods with more restrictions (in terms of the applicable range of void fraction, liquid Prandtl number or liquid

  5. Triangular blasting into limited voids for vertical free face retorts

    SciTech Connect

    Ricketts, T.E.

    1981-04-21

    Oil shale formation is explosively expanded toward a limited void volume for forming an in situ oil shale retort in a subterranean formation containing oil shale. In one embodiment, the retort is formed by excavating a narrow vertical slot diagonally across a retort site of rectangular horizontal crosssection, leaving separate triangular zones of unfragmented formation within the retort site on opposite sides of the diagonal slot. Explosive is placed in a plurality of vertical blasting holes drilled in each triangular zone of formation, and such explosive is detonated for explosively expanding formation within the triangular zones toward vertical free faces adjacent the slot for forming a fragmented permeable mass of formation particles containing oil shale. Detonation of explosive in the blasting holes expands separate wedge-shaped segments of formation toward the diagonal slot, owing to the natural cratering effect of each blast, causing the wedge-shaped segments being expanded to conform generally to the side boundaries of each triangular zone, and producing reasonably good fragmentation and movement of expanded formation toward the slot from formation throughout the retort site. Several such slots can be employed in forming a retort.

  6. Clusters, voids and reconstructions of the cosmic web

    NASA Astrophysics Data System (ADS)

    Bos, E. G. Patrick

    2016-12-01

    The Universe is filled for 95% with dark matter and energy that we cannot see. Of the remaining 5% normal matter we can only see a small part. However, if we want to study the Universe as a whole, we will have to get to know it for 100%. We have to uncover indirectly where dark matter is hiding and what is the nature of dark energy. In this thesis we explore two such methods. The first part describes how we can use the large empty regions between galaxies, "voids", to learn more about dark energy. We converted our theoretical simulations to a model of real observations of galaxies. In this model, we perform the same measurements as we would in real observations. This way, we show that it is indeed possible to unravel the nature of dark energy. The second part is based on our computer code: BARCODE. It unites two models: a physical model of the formation of the Cosmic Web, and a description of the observational effects of (clusters of) galaxies, in particular the effect of redshift on distance measurements. It allows us to back-trace our observations to the primordial conditions. These enable us to trace all (dark) matter, also that which we did not directly observe. The result is a reconstruction of the complete Cosmic Web. In these, we studied "filaments". These objects have not yet been extensively studied. BARCODE will enable further study, e.g. by using it to find observable filaments.

  7. Brane surgery: energy conditions, traversable wormholes, and voids

    NASA Astrophysics Data System (ADS)

    Barceló1, C.; Visser, M.

    2000-09-01

    Branes are ubiquitous elements of any low-energy limit of string theory. We point out that negative tension branes violate all the standard energy conditions of the higher-dimensional spacetime they are embedded in; this opens the door to very peculiar solutions of the higher-dimensional Einstein equations. Building upon the (/3+1)-dimensional implementation of fundamental string theory, we illustrate the possibilities by considering a toy model consisting of a (/2+1)-dimensional brane propagating through our observable (/3+1)-dimensional universe. Developing a notion of ``brane surgery'', based on the Israel-Lanczos-Sen ``thin shell'' formalism of general relativity, we analyze the dynamics and find traversable wormholes, closed baby universes, voids (holes in the spacetime manifold), and an evasion (not a violation) of both the singularity theorems and the positive mass theorem. These features appear generic to any brane model that permits negative tension branes: This includes the Randall-Sundrum models and their variants.

  8. Sizes of voids as a test for dark matter models

    NASA Astrophysics Data System (ADS)

    Ghigna, Sebastiano; Borgani, Stefano; Bonometto, Silvio A.; Guzzo, Luigi; Klypin, Anatoly; Primack, Joel R.; Giovanelli, Riccardo; Haynes, Martha P.

    1994-12-01

    We use the void probability function (VPF) to study the distribution of galaxies in a volume-limited sub-sample of the Perseus-Pisces survey. We compare observational results with theoretical predictions based on high-resolution N-body simulations for two realizations of the cold + hot dark matter (CHDM) model and for unbiased (b = 1) and biased (b = 1.5) cold dark matter (CDM) models in a 50/h Mpc box. We identify galaxies as peaks of the evolved density field. Overmerged structures are fragmented into individual galaxies so as to reproduce both the correct luminosity function (after assuming M/L values for the resulting galaxy groups) and the two-point correlation function. We also try to reproduce the observational biases of the observational data as best we can. Our main result is that on intermediate 2-8/h Mpc scales the VPF for the standard CHDM model with Omega cold/Omega hot/Omega bar = 0.6/0.3/0.1 exceeds the observational VPF with a high confidence level. CDM models produce smaller VPF, whose shape is independent of the biasing parameter. We verify the robustness of this result against changing the observer position in the simulations and the threshold for galaxy identification.

  9. Voiding cystourethrogram: How much should we be selective?

    PubMed Central

    Yel, Sibel; Tülpar, Sebahat; Düşünsel, Ruhan; Poyrazoğlu, Hakan Muammer; Dursun, İsmail; Abdülrezzak, Ümmühan; Gündüz, Zübeyde; Yılmaz, Kenan; Baştuğ, Funda

    2017-01-01

    Objective In this study, we examined the patients’ characteristics, who underwent voiding cystourethrography (VCUG), in order to determine any selectivity for indication of this invasive method. Material and methods After exclusion of indications of neurogenic bladder or antenatal hydronephrosis and control VCUGs, 159 VCUGs performed in our clinic within one year were evaluated. Patients are divided into three groups accoding to age. Clinical characteristic and findings of renal ultrasonography (US) and renal scintigraphy were examined. Results Vesicoureteral reflux (VUR) was detected in 61 (38.3%) of 159 patients who underwent cystourethrographic examinations, in 45.8% of the patients with a history of recurrent urinary tract infection (UTI), in 22.0% of the patients with pathological urinary system US without history of recurrent UTI. High-grade reflux rate was significantly more frequent in renal units with pathological US findings. Severe scar was significantly more frequent in renal units with high-grade reflux when compared to renal units without reflux and those with low-grade reflux. Predictive values of recurrent UTI, scarring status and pathological US for VUR were separately analyzed and seen that likelihood of indicating VUR was increased when all 3 risk factors were assessed together. Conclusion Vesicoureteral reflux is a problem in which diagnostic process and management strategy should have to be considered in individualized manner for each patient. Before prescribing invasive VCUG, imaging urinary system by US and scintigraphy and determining whether there is recurrent UTI will improve selectivity and success of VCUG. PMID:28270956

  10. Comparing Information Assurance Awareness Training for End-Users: A Content Analysis Examination of Air Force and Defense Information Systems Agency User Training Modules

    DTIC Science & Technology

    2008-03-01

    5   Information Assurance and Awareness Defined...Policy Directives (AFPD) and Air Force Instructions (AFI) to 5 encompass network security for AF networks and information systems. AFPD 33-2...of the research, discussing the findings and the limitations of the methodology used in this thesis. Chapter 5 will offer conclusions based on the

  11. On localization and void coalescence as a precursor to ductile fracture.

    PubMed

    Tekoğlu, C; Hutchinson, J W; Pardoen, T

    2015-03-28

    Two modes of plastic flow localization commonly occur in the ductile fracture of structural metals undergoing damage and failure by the mechanism involving void nucleation, growth and coalescence. The first mode consists of a macroscopic localization, usually linked to the softening effect of void nucleation and growth, in either a normal band or a shear band where the thickness of the band is comparable to void spacing. The second mode is coalescence with plastic strain localizing to the ligaments between voids by an internal necking process. The ductility of a material is tied to the strain at macroscopic localization, as this marks the limit of uniform straining at the macroscopic scale. The question addressed is whether macroscopic localization occurs prior to void coalescence or whether the two occur simultaneously. The relation between these two modes of localization is studied quantitatively in this paper using a three-dimensional elastic-plastic computational model representing a doubly periodic array of voids within a band confined between two semi-infinite outer blocks of the same material but without voids. At sufficiently high stress triaxiality, a clear separation exists between the two modes of localization. At lower stress triaxialities, the model predicts that the onset of macroscopic localization and coalescence occur simultaneously.

  12. In situ oil shale retort having horizontal voids with side pillars

    SciTech Connect

    Ricketts, T.E.; Burton, R.S.

    1984-06-12

    An in situ oil shale retort is formed in a subterranean formation containing oil shale by excavating one or more horizontally extending voids across a retort site, leaving a zone of unfragmented formation having a horizontal free face adjacent such a horizontal void. In one embodiment, such a horizontal void is excavated across less than the entire width of the retort site, leaving ''side pillars'' of unfragmented formation spaced inwardly from adjacent side boundaries of the retort site at opposite sides of such a horizontal void. This reduces the maximum span of the horizontal void, when compared with supporting overburden above the void with one or more interior isolated pillars spaced inwardly from the side boundaries of the retort. The side pillars are explosively expanded. Then such a zone of unfragmented formation is explosively expanded toward such a horizontal void for forming a fragmented permeable mass of formation particles containing oil shale in the retort. The resulting fragmented mass can have a slightly narrowed region along the sides where the side pillars were present.

  13. DIVE in the cosmic web: voids with Delaunay triangulation from discrete matter tracer distributions

    NASA Astrophysics Data System (ADS)

    Zhao, Cheng; Tao, Charling; Liang, Yu; Kitaura, Francisco-Shu; Chuang, Chia-Hsun

    2016-07-01

    We present a novel parameter-free cosmological void finder (DIVE, Delaunay TrIangulation Void findEr) based on Delaunay Triangulation (DT), which efficiently computes the empty spheres constrained by a discrete set of tracers. We define the spheres as DT voids, and describe their properties, including a universal density profile together with an intrinsic scatter. We apply this technique on 100 halo catalogues with volumes of 2.5 h-1Gpc side each, with a bias and number density similar to the Baryon Oscillation Spectroscopic Survey CMASS luminous red galaxies, performed with the PATCHY code. Our results show that there are two main species of DT voids, which can be characterized by the radius: they have different responses to halo redshift space distortions, to number density of tracers, and reside in different dark matter environments. Based on dynamical arguments using the tidal field tensor, we demonstrate that large DT voids are hosted in expanding regions, whereas the haloes used to construct them reside in collapsing ones. Our approach is therefore able to efficiently determine the troughs of the density field from galaxy surveys, and can be used to study their clustering. We further study the power spectra of DT voids, and find that the bias of the two populations are different, demonstrating that the small DT voids are essentially tracers of groups of haloes.

  14. a New Algorithm for Void Filling in a Dsm from Stereo Satellite Images in Urban Areas

    NASA Astrophysics Data System (ADS)

    Gharib Bafghi, Z.; Tian, J.; d'Angelo, P.; Reinartz, P.

    2016-06-01

    Digital Surface Models (DSM) derived from stereo-pair satellite images are the main sources for many Geo-Informatics applications like 3D change detection, object classification and recognition. However since occlusion especially in urban scenes result in some deficiencies in the stereo matching phase, these DSMs contain some voids. In order to fill the voids a range of algorithms have been proposed, mainly including interpolation alone or along with auxiliary DSM. In this paper an algorithm for void filling in DSM from stereo satellite images has been developed. Unlike common previous approaches we didn't use any external DSM to fill the voids. Our proposed algorithm uses only the original images and the unfilled DSM itself. First a neighborhood around every void in the unfilled DSM and its corresponding area in multispectral image is defined. Then it is analysed to extract both spectral and geometric texture and accordingly to assign labels to each cell in the voids. This step contains three phases comprising shadow detection, height thresholding and image segmentation. Thus every cell in void has a label and is filled by the median value of its co-labelled neighbors. The results for datasets from WorldView-2 and IKONOS are shown and discussed.

  15. Impact of glissile interstitial loop production in cascades on void ordering and swelling saturation under irradiation

    NASA Astrophysics Data System (ADS)

    Dubinko, V. I.

    1995-08-01

    According to the dislocation model of void ordering and swelling saturation by the present author, these phenomena arise due to the absorption by voids of perfect glissile dislocation loops produced by irradiation. The formation and glide of small interstitial loops has been also confirmed by recent molecular dynamics (MD) studies of displacement cascades. The cascade mechanism of the loop production is shown to explain an absence of visible dislocation loops in some experiments on void lattices, which is a very important argument in favor of the present theory. However, according to the MD simulations, the glide of such loops seems not to depend on the stacking fault energy of the host lattice, contrary to the predictions of the elastic continuum theory. The latter shows that high stacking energy (as in most bcc metals and in fcc Ni and Al) favors the unfaulting of small loops, which seems to be in agreement with experimentally observed void lattice formation in these metals as compared to the resistance of the low stacking energy metals (such as Cu, Ag, Au and most steels) to void lattice formation. This discrepancy between continuum theory and MD simulations shows the need for further studies of displacement cascades, in particular, in more complex systems modeling the effects of impurities on the nature of interstitial clusters. An outstanding problem is to find impurities that can facilitate the unfaulting process and, hence, void ordering and swelling saturation in those fcc metals which are currently supposed to be void lattice resistant.

  16. Stress Voiding in IC Interconnects - Rules of Evidence for Failure Analysts

    SciTech Connect

    FILTER, WILLIAM F.

    1999-09-17

    Mention the words ''stress voiding'', and everyone from technology engineer to manager to customer is likely to cringe. This IC failure mechanism elicits fear because it is insidious, capricious, and difficult to identify and arrest. There are reasons to believe that a damascene-copper future might be void-free. Nevertheless, engineers who continue to produce ICs with Al-alloy interconnects, or who assess the reliability of legacy ICs with long service life, need up-to-date insights and techniques to deal with stress voiding problems. Stress voiding need not be fearful. Not always predictable, neither is it inevitable. On the contrary, stress voids are caused by specific, avoidable processing errors. Analytical work, though often painful, can identify these errors when stress voiding occurs, and vigilance in monitoring the improved process can keep it from recurring. In this article, they show that a methodical, forensics approach to failure analysis can solve suspected cases of stress voiding. This approach uses new techniques, and patiently applies familiar ones, to develop evidence meeting strict standards of proof.

  17. Active Adoption of Void Formation in Metal-Oxide for All Transparent Super-Performing Photodetectors

    NASA Astrophysics Data System (ADS)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-05-01

    Could ‘defect-considered’ void formation in metal-oxide be actively used? Is it possible to realize stable void formation in a metal-oxide layer, beyond unexpected observations, for functional utilization? Herein we demonstrate the effective tailoring of void formation of NiO for ultra-sensitive UV photodetection. NiO was formed onto pre-sputtered ZnO for a large size and spontaneously formed abrupt p-NiO/n-ZnO heterojunction device. To form voids at an interface, rapid thermal process was performed, resulting in highly visible light transparency (85–95%). This heterojunction provides extremely low saturation current (<0.1 nA) with an extraordinary rectifying ratio value of over 3000 and works well without any additional metal electrodes. Under UV illumination, we can observe the fast photoresponse time (10 ms) along with the highest possible responsivity (1.8 A W‑1) and excellent detectivity (2 × 1013 Jones) due to the existence of an intrinsic-void layer at the interface. We consider this as the first report on metal-oxide-based void formation (Kirkendall effect) for effective photoelectric device applications. We propose that the active adoption of ‘defect-considered’ Kirkendall-voids will open up a new era for metal-oxide based photoelectric devices.

  18. Voids at the tunnel-soil interface for calculation of ground vibration from underground railways

    NASA Astrophysics Data System (ADS)

    Jones, Simon; Hunt, Hugh

    2011-01-01

    Voids at the tunnel-soil interface are not normally considered when predicting ground vibration from underground railways. The soil is generally assumed to be continuously bonded to the outer surface of the tunnel to simplify the modelling process. Evidence of voids around underground railways motivated the study presented herein to quantify the level of uncertainty in ground vibration predictions associated with neglecting to include such voids at the tunnel-soil interface. A semi-analytical method is developed which derives discrete transfers for the coupled tunnel-soil model based on the continuous Pipe-in-Pipe method. The void is simulated by uncoupling the appropriate nodes at the interface to prevent force transfer between the systems. The results from this investigation show that relatively small voids ( 4 m×90∘) can significantly affect the rms velocity predictions in the near-field and moderately affect predictions in the far-field. Sensitivity of the predictions to void length and void sector angle are both deemed to be significant. The findings from this study suggest that the uncertainty associated with assuming a perfect bond at the tunnel-soil interface in an area with known voidage can reasonably reach ±5 dB and thus should be considered in the design process.

  19. Active Adoption of Void Formation in Metal-Oxide for All Transparent Super-Performing Photodetectors

    PubMed Central

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-01-01

    Could ‘defect-considered’ void formation in metal-oxide be actively used? Is it possible to realize stable void formation in a metal-oxide layer, beyond unexpected observations, for functional utilization? Herein we demonstrate the effective tailoring of void formation of NiO for ultra-sensitive UV photodetection. NiO was formed onto pre-sputtered ZnO for a large size and spontaneously formed abrupt p-NiO/n-ZnO heterojunction device. To form voids at an interface, rapid thermal process was performed, resulting in highly visible light transparency (85–95%). This heterojunction provides extremely low saturation current (<0.1 nA) with an extraordinary rectifying ratio value of over 3000 and works well without any additional metal electrodes. Under UV illumination, we can observe the fast photoresponse time (10 ms) along with the highest possible responsivity (1.8 A W−1) and excellent detectivity (2 × 1013 Jones) due to the existence of an intrinsic-void layer at the interface. We consider this as the first report on metal-oxide-based void formation (Kirkendall effect) for effective photoelectric device applications. We propose that the active adoption of ‘defect-considered’ Kirkendall-voids will open up a new era for metal-oxide based photoelectric devices. PMID:27151288

  20. Void Growth and Coalescence in Dynamic Fracture from the Atomistic Level

    SciTech Connect

    Rudd, R E

    2010-09-30

    An important example of multiscale material response is the fracture of ductile solids. In the process of ductile fracture, voids nucleate, grow and coalesce, and it is this linking process that creates the fracture. Ductile fracture has typically been modeled at the continuum level, in a variety of models that may or may not model voids explicitly. Previously we have studied the plasticity associated with void growth in fcc metals, focusing on copper. In the work discussed here we examine void growth in single crystal and polycrystalline body-centered cubic (bcc) metals (V, Nb, Ta, Mo and W) subjected to tension at a high rate and high triaxiality. Large-scale atomistic models provide detailed information on void nucleation and growth and the plasticity generated as voids coalesce, based solely on the constitutive properties inherent in the interatomic forces. The details of the plasticity may be used to inform dislocation dynamics and continuum plasticity models in order to develop models that scale beyond the nanoscale. We also discuss concurrent multiscale modeling of void growth using Coarse-Grained Molecular Dynamics.

  1. Microstructural characterization of XLPE electrical insulation in power cables: determination of void size distributions using TEM

    NASA Astrophysics Data System (ADS)

    Markey, L.; Stevens, G. C.

    2003-10-01

    In an effort to progress in our understanding of the ageing mechanisms of high voltage cables submitted to electrical and thermal stresses, we present a quantitative study of voids, the defects which are considered to be partly responsible for cable failure. We propose a method based on large data sets of transmission electron microscopy (TEM) observations of replicated samples allowing for the determination of void concentration distribution as a function of void size in the mesoscopic to microscopic range at any point in the cable insulation. A theory is also developed to calculate the effect of etching on the apparent size of the voids observed. We present the first results of this sort ever obtained on two industrial cables, one of which was aged in an AC field. Results clearly indicate that a much larger concentration of voids occur near the inner semiconductor compared to the bulk of the insulation, independently of ageing. An effect of ageing can also be seen near the inner semiconductor, resulting in an increase in the total void internal surface area and a slight shift of the concentration curve towards larger voids, with the peak moving from about 40 nm to about 50 nm.

  2. Thermal stability of interface voids in Cu grain boundaries with molecular dynamic simulations

    NASA Astrophysics Data System (ADS)

    Xydou, A.; Parviainen, S.; Aicheler, M.; Djurabekova, F.

    2016-09-01

    By means of molecular dynamic simulations, the stability of cylindrical voids is examined with respect to the diffusion bonding procedure. To do this, the effect of grain boundaries between the grains of different crystallographic orientations on the void closing time was studied at high temperatures from 0.7 up to 0.94 of the bulk melting temperature ({{T}\\text{m}} ). The diameter of the voids varied from 3.5 to 6.5 nm. A thermal instability occurring at high temperatures at the surface of the void placed in a grain boundary triggered the eventual closure of the void at all examined temperatures. The closing time has an exponential dependence on the examined temperature values. A model based on the defect diffusion theory is developed to predict the closing time for voids of macroscopic size. The diffusion coefficient within the grain boundaries is found to be overall higher than the diffusion coefficient in the region around the void surface. The activation energy for the diffusion in the grain boundary is calculated based on molecular dynamic simulations. This value agrees well with the experimental given in the Ashby maps for the creep in copper via Coble GB diffusion.

  3. The influence of void ratio on small strain shear modulus of granular materials: A micromechanical perspective

    NASA Astrophysics Data System (ADS)

    Xu, Xiaomin; Cheng, Yipik; Ling, Dongsheng

    2013-06-01

    The small strain shear modulus Gmax of granular materials is highly dependent on their current void ratio and stress state, generally expressed as the famous Hardin and Richart equation. Various forms of void ratio functions have been proposed, either based on experimental or theoretical research. It is noted that each of them can be applied for a certain soil within a limited void ratio range. Micromechanical studies on the influence of void ratio on Gmax are conducted in this paper, using Discrete Element Method. After each sample being isotropically consolidated, shear wave velocity is measured by applying a velocity pulse to the transmitter in a certain direction, and monitoring the corresponding average velocity of the receiver. The capabilities of various existing void ratio functions are examined, together with the relationship between coordination number and void ratio, distribution of coordination number, as well as the contact force network. The void ratio effect on Gmax is further explained in terms of the wave travel length and the travel time for different contact connectivity networks.

  4. Dislocation pile-ups as sites for formation of electromigration-induced transgranular slit-like voids in Al interconnects

    SciTech Connect

    Srikar, V.T.; Thompson, C.V.

    1999-12-17

    Electromigration-induced voiding in metal interconnects in Si integrated circuits is a serious reliability concern. The microstructure of narrow interconnects subject to post-pattern anneal is expected to be bamboo-like in character. These structures are best described as chains of single crystals, with grain boundaries perpendicular to the interconnect axis. In these microstructures, two distinct types of void morphologies have been reported in Al-alloy interconnects: large, wedge shaped erosion voids (E-voids), and narrow slit-like voids (S-voids). A summarized below, electromigration experiments conducted on single-crystal Al interconnects have clearly shown that the transition of erosion voids to slit-like voids is very strongly dependent on the crystallography of the interconnect, and also that there is some inhomogeneously distributed feature which triggers S-void formation, even in single-crystal interconnects. In summary, the authors feel that the strong crystallographic dependence of the S-voids, the possible effects of the enormous mechanical stresses (in excess of 1 GPa in some cases) which can exist in such interconnects, and the stochastic nature of the development of slit-like features, have not been adequately captured in the existing models. In what follows, the authors present a model for a role that dislocation pile-ups may play in reducing the energy of transition of E-voids to S-voids, and for controlling the location of this transition.

  5. Infrared Microspectroscopy of Bionanomaterials (Diatoms) with Careful Evaluation of Void Effects.

    PubMed

    Alipour, Leila; Hamamoto, Mai; Nakashima, Satoru; Harui, Rika; Furiki, Masanari; Oku, Osamu

    2016-03-01

    In order to characterize a representative natural bionanomaterial, present day centric diatom samples (diameter, 175-310 µm) have been analyzed and imaged by infrared (IR) micro-spectroscopy and scanning electron microscopy (SEM). Because diatom silica frustules have complex microscopic morphology, including many void areas such as micro- or nano-pores, the effects of voids on the spectral band shapes were first evaluated. With increasing void area percentage, 1220 cm(-1)/1070 cm(-1) peak height ratio (Si-O polymerization index) increases and 950 cm(-1)/800 cm(-1) peak height ratio (Si-OH/Si-O-Si) decreases, both approaching 1. Based on the void area percentage of representative diatom samples determined using SEM image analyses (51.5% to 20.5%) and spectral simulation, the 1220 cm(-1)/1070 cm(-1) ratios of diatom samples are sometimes affected by the void effect, but the 950 cm(-1)/800 cm(-1) ratios can indicate real structural information of silica. This void effect should be carefully evaluated for IR micro-spectroscopy of micro-nano-porous materials. Maturity of diatom specimens may be evaluated from: (1) void area percentages determined by SEM; (2) average thicknesses determined by optical microscope; and (3) average values of 1220 cm(-1)/1070 cm(-1) peak height ratios (opposite trend to the void effect) determined by IR micro-spectroscopy. Microscopic heterogeneities of chemical structures of silica were obtained by IR micro-spectroscopic mapping of four representative diatoms. The 950 cm(-1)/800 cm(-1) ratios show that large regions of some diatoms consist of hydrated amorphous immature silica. The successful analysis of diatoms by IR micro-spectroscopic data with careful void effect evaluation may be applied to physicochemical structures of many other bionanomaterials.

  6. Influence of entrapped air pockets on hydraulic transients in water pipelines

    SciTech Connect

    Zhou, Ling; Liu, Prof. Deyou; Karney, Professor Byran W.; Zhang, Qin Fen

    2011-01-01

    The pressure variations associated with a filling undulating pipeline containing an entrapped air pocket are investigated both experimentally and numerically. The influence of entrapped air on abnormal transient pressures is often ambiguous since the compressibility of the air pocket permits the liquid flow to accelerate but also partly cushions the system, with the balance of these tendencies being associated with the initial void fraction of the air pocket. Earlier experimental research involved systems with an initial void fraction greater than 5.8%; this paper focuses on initial void fractions ranging from 0% to 10%, in order to more completely characterize the transient response. Experimental results show that the maximum pressure increases and then decreases as the initial void fraction decreases. A simplified model is developed by neglecting the liquid inertia and energy loss of a short water column near the air-water interface. Comparisons of the calculated and observed results show the model is able to accurately predict peak pressures as a function of void fraction and filling conditions. Rigid water column models, however, perform poorly with small void fractions.

  7. Subchannel Thermal Hydraulic Experimental Program (STEP). Volume 2. Void fraction by gamma scattering. Final report. [PWR

    SciTech Connect

    Zielke, L.A.; Grant, K.W.; MacKinnon, J.G.

    1980-08-01

    This volume provides a description of the gamma-scattering technique for the measurement of local void fraction within complex geometries. The technique was applied to measurements in the center subchannel of a 4 x 4 array of electrically heated rods with four heated walls. Over 300 data points were obtained covering thermal-hydraulic conditions typical of light water reactors. Results indicate a large variation of void fraction within the center subchannel and a measured-average void fraction higher than predicted by the COBRA IV computer code.

  8. Modeling void growth and movement with phase change in thermal energy storage canisters

    NASA Technical Reports Server (NTRS)

    Darling, Douglas; Namkoong, David; Skarda, J. Raymond Lee

    1993-01-01

    A scheme was developed to model the thermal hydrodynamic behavior of thermal energy storage salts. The model included buoyancy, surface tension, viscosity, phases change with density difference, and void growth and movement. The energy, momentum, and continuity equations were solved using a finite volume formulation. The momentum equation was divided into two pieces. The void growth and void movement are modeled between the two pieces of the momentum equations. Results showed this scheme was able to predict the behavior of thermal energy storage salts.

  9. Blocking effect of twin boundaries on partial dislocation emission from void surfaces.

    PubMed

    Zhang, Lifeng; Zhou, Haofei; Qu, Shaoxing

    2012-03-02

    Recent discovery that nanoscale twin boundaries can be introduced in ultrafine-grained metals to improve strength and ductility has renewed interest in the mechanical behavior and deformation mechanisms of these nanostructured materials. By controlling twin boundary spacing, the effect of twin boundaries on void growth is investigated by using atomistic simulation method. The strength is significantly enhanced due to the discontinuous slip system associated with these coherent interfaces. Atomic-scale mechanisms underlying void growth, as well as the interaction between twin boundaries and the void, are revealed in details.

  10. Comparison of void strengthening in fcc and bcc metals : large-scale atomic-level modelling.

    SciTech Connect

    Osetskiy, Yury N; Bacon, David J

    2005-01-01

    Strengthening due to voids can be a significant radiation effect in metals. Treatment of this by elasticity theory of dislocations is difficult when atomic structure of the obstacle and dislocation is influential. In this paper, we report results of large-scale atomic-level modelling of edge dislocation-void interaction in fcc (copper) and bcc (iron) metals. Voids of up to 5 nm diameter were studied over the temperature range from 0 to 600 K. We demonstrate that atomistic modelling is able to reveal important effects, which are beyond the continuum approach. Some arise from features of the dislocation core and crystal structure, others involve dislocation climb and temperature effects.

  11. Detector response in a CANDU low void reactivity core

    SciTech Connect

    Tsang, K. T.

    2006-07-01

    The response of the in-core flux detectors to the CANFLEX Low-Void-Reactivity Fuel (LVRF) [1] bundles for use in the CANDU reactor at Bruce nuclear generation station has been studied. The study was based on 2 detector types - platinum (Pt)-clad Inconel and pure Inconel detectors, and 2 fuel types - LVRF bundles and natural-uranium (NU) bundles. Both detectors show a decrease of thermal-neutron-flux to total-photon-flux ratio when NU fuel bundles are replaced by LVRF bundles in the reactor core (7% for Inconel and 9% for Pt-clad detectors). The ratio of the prompt component of the net electron current to the total net electron current (PFe) of the detectors however shows a different response. The use of LVRF bundles in place of NU fuel bundles in the reactor core did not change the PFe of the Pt-clad Inconel detector but increased the PFe of the pure Inconel detector by less than 2%. The study shows that the Inconel detector has a larger prompt-detector response than that of the platinum-clad detector; it reacts to the change of fluxes in the reactor core more readily. On the other hand, the Pt-clad detector is less sensitive to perturbations of the neutron-to-gamma ratio. Nevertheless the changes in an absolute sense are minimal; one does not anticipate a change of the flux-monitoring system if the NU fuel bundles are replaced with the CANFLEX LVRF bundles in the core of the Bruce nuclear generating station. (authors)

  12. RELAXATION OF BLAZAR-INDUCED PAIR BEAMS IN COSMIC VOIDS

    SciTech Connect

    Miniati, Francesco; Elyiv, Andrii

    2013-06-10

    The stability properties of a low-density ultrarelativistic pair beam produced in the intergalactic medium (IGM) by multi-TeV gamma-ray photons from blazars are analyzed. The problem is relevant for probes of magnetic field in cosmic voids through gamma-ray observations. In addition, dissipation of such beams could considerably affect the thermal history of the IGM and structure formation. We use a Monte Carlo method to quantify the properties of the blazar-induced electromagnetic shower, in particular the bulk Lorentz factor and the angular spread of the pair beam generated by the shower, as a function of distance from the blazar itself. We then use linear and nonlinear kinetic theory to study the stability of the pair beam against the growth of electrostatic plasma waves, employing the Monte Carlo results for our quantitative estimates. We find that the fastest growing mode, like any perturbation mode with even a very modest component perpendicular to the beam direction, cannot be described in the reactive regime. Due to the effect of nonlinear Landau damping, which suppresses the growth of plasma oscillations, the beam relaxation timescale is found to be significantly longer than the inverse Compton loss time. Finally, density inhomogeneities associated with cosmic structure induce loss of resonance between the beam particles and plasma oscillations, strongly inhibiting their growth. We conclude that relativistic pair beams produced by blazars in the IGM are stable on timescales that are long compared with the electromagnetic cascades. There appears to be little or no effect of pair beams on the IGM.

  13. The Effect of Crumb Rubber Particle Size to the Optimum Binder Content for Open Graded Friction Course

    PubMed Central

    Ibrahim, Mohd Rasdan; Katman, Herda Yati; Karim, Mohamed Rehan; Koting, Suhana; Mashaan, Nuha S.

    2014-01-01

    The main objective of this paper is to investigate the relations of rubber size, rubber content, and binder content in determination of optimum binder content for open graded friction course (OGFC). Mix gradation type B as specified in Specification for Porous Asphalt produced by the Road Engineering Association of Malaysia (REAM) was used in this study. Marshall specimens were prepared with four different sizes of rubber, namely, 20 mesh size [0.841 mm], 40 mesh [0.42 mm], 80 mesh [0.177 mm], and 100 mesh [0.149 mm] with different concentrations of rubberised bitumen (4%, 8%, and 12%) and different percentages of binder content (4%–7%). The appropriate optimum binder content is then selected according to the results of the air voids, binder draindown, and abrasion loss test. Test results found that crumb rubber particle size can affect the optimum binder content for OGFC. PMID:24574875

  14. Three-Dimensional Computed Tomography as a Method for Finding Die Attach Voids in Diodes

    NASA Technical Reports Server (NTRS)

    Brahm, E. N.; Rolin, T. D.

    2010-01-01

    NASA analyzes electrical, electronic, and electromechanical (EEE) parts used in space vehicles to understand failure modes of these components. The diode is an EEE part critical to NASA missions that can fail due to excessive voiding in the die attach. Metallography, one established method for studying the die attach, is a time-intensive, destructive, and equivocal process whereby mechanical grinding of the diodes is performed to reveal voiding in the die attach. Problems such as die attach pull-out tend to complicate results and can lead to erroneous conclusions. The objective of this study is to determine if three-dimensional computed tomography (3DCT), a nondestructive technique, is a viable alternative to metallography for detecting die attach voiding. The die attach voiding in two- dimensional planes created from 3DCT scans was compared to several physical cross sections of the same diode to determine if the 3DCT scan accurately recreates die attach volumetric variability

  15. Quantifying voids effecting delamination in carbon/epoxy composites: static and fatigue fracture behavior

    NASA Astrophysics Data System (ADS)

    Hakim, I.; May, D.; Abo Ras, M.; Meyendorf, N.; Donaldson, S.

    2016-04-01

    On the present work, samples of carbon fiber/epoxy composites with different void levels were fabricated using hand layup vacuum bagging process by varying the pressure. Thermal nondestructive methods: thermal conductivity measurement, pulse thermography, pulse phase thermography and lock-in-thermography, and mechanical testing: modes I and II interlaminar fracture toughness were conducted. Comparing the parameters resulted from the thermal nondestructive testing revealed that voids lead to reductions in thermal properties in all directions of composites. The results of mode I and mode II interlaminar fracture toughness showed that voids lead to reductions in interlaminar fracture toughness. The parameters resulted from thermal nondestructive testing were correlated to the results of mode I and mode II interlaminar fracture toughness and voids were quantified.

  16. Conclusive evidence of abrupt coagulation inside the void during cyclic nanoparticle formation in reactive plasma

    NASA Astrophysics Data System (ADS)

    van de Wetering, F. M. J. H.; Nijdam, S.; Beckers, J.

    2016-07-01

    In this letter, we present scanning electron microscopy (SEM) results that confirm in a direct way our earlier explanation of an abrupt coagulation event as the cause for the void hiccup. In a recent paper, we reported on the fast and interrupted expansion of voids in a reactive dusty argon-acetylene plasma. The voids appeared one after the other, each showing a peculiar, though reproducible, behavior of successive periods of fast expansion, abrupt contraction, and continued expansion. The abrupt contraction was termed "hiccup" and was related to collective coagulation of a new generation of nanoparticles growing in the void using relatively indirect methods: electron density measurements and optical emission spectroscopy. In this letter, we present conclusive evidence using SEM of particles collected at different moments in time spanning several growth cycles, which enables us to follow the nanoparticle formation process in great detail.

  17. Proton Irradiation-Induced Metal Voids in Gallium Nitride High Electron Mobility Transistors

    DTIC Science & Technology

    2015-09-01

    A model was developed to predict void sizes versus dose and validated using data on dislocation density. 14. SUBJECT TERMS radiation , Kirkendall...8   4.   Proton Radiation Effects...Irradiated Devices ............................................................................. 53   E.   VARYING RADIATION FLUENCE DEVICES

  18. 40 CFR 86.1114-87 - Suspension and voiding of certificates of conformity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... into commerce pursuant to § 86.1106-87(a)(4)(ii), (b)(6)(ii), (c)(5)(ii) or (d)(2)(ii). (g) The... satisfaction that the decision to suspend or void the certificate was based on erroneous information,...

  19. Atypical cells in a voided urine cytology specimen in a renal transplant recipient.

    PubMed

    Lu, Miao; Ho, Julie; Azordegan, Nazila; Perry, Anamarija M; Gibson, Ian W; Baker, Patricia

    2017-01-01

    Voided urine is routinely collected from renal transplant patients to screen for polyomavirus. In rare cases, atypical lymphoid cells can be detected in voided urine and raise the suspicion of post-transplant lymphoproliferative disorder (PTLD). However, further immunohistochemistry of the cell block and flow cytometry is frequently limited by the low cellularity and poor preservation of voided urine. Therefore, PTLD of the renal allograft is usually diagnosed from tissue biopsy or nephrectomy specimens. Herein, we report a rare case of atypical cells in a voided urine cytology specimen from a kidney transplant recipient. Needle core biopsy of the renal allograft showed monomorphic PTLD. Diagn. Cytopathol. 2017;45:69-72. © 2016 Wiley Periodicals, Inc.

  20. Structural analyses of a rigid pavement overlaying a sub-surface void

    NASA Astrophysics Data System (ADS)

    Adam, Fatih Alperen

    Pavement failures are very hazardous for public safety and serviceability. These failures in pavements are mainly caused by subsurface voids, cracks, and undulation at the slab-base interface. On the other hand, current structural analysis procedures for rigid pavement assume that the slab-base interface is perfectly planar and no imperfections exist in the sub-surface soil. This assumption would be violated if severe erosion were to occur due to inadequate drainage, thermal movements, and/or mechanical loading. Until now, the effect of erosion was only considered in the faulting performance model, but not with regards to transverse cracking at the mid-slab edge. In this research, the bottom up fatigue cracking potential, caused by the combined effects of wheel loading and a localized imperfection in the form of a void below the mid-slab edge, is studied. A robust stress and surface deflection analysis was also conducted to evaluate the influence of a sub-surface void on layer moduli back-calculation. Rehabilitative measures were considered, which included a study on overlay and fill remediation. A series regression of equations was proposed that provides a relationship between void size, layer moduli stiffness, and the overlay thickness required to reduce the stress to its original pre-void level. The effect of the void on 3D pavement crack propagation was also studied under a single axle load. The amplifications to the stress intensity was shown to be high but could be mitigated substantially if stiff material is used to fill the void and impede crack growth. The pavement system was modeled using the commercial finite element modeling program Abaqus RTM. More than 10,000 runs were executed to do the following analysis: stress analysis of subsurface voids, E-moduli back-calculation of base layer, pavement damage calculations of Beaumont, TX, overlay thickness estimations, and mode I crack analysis. The results indicate that the stress and stress intensity are, on

  1. Quantitative void fraction measurement with an eddy current flowmeter for generation IV Sodium cooled Fast Reactor

    SciTech Connect

    Kumar, M.; Tordjeman, Ph.; Bergez, W.; Cavaro, M.; Paumel, K.; Jeannot, J.P.

    2015-07-01

    This study was carried out to understand the response of an eddy current type flowmeter in two phase liquid-metal flow. We use the technique of ellipse fit and correlate the fluctuations in the angle of inclination of this ellipse with the void fraction. The effects of physical parameters such as coil excitation frequency and flow velocity have been studied. The results show the possibility of using an eddy current flowmeter as a gas detector for large void fractions. (authors)

  2. Quantitative void fraction detection with an eddy current flowmeter for generation IV Sodium cooled Fast Reactor

    SciTech Connect

    Kumar, M.; Tordjeman, Ph.; Bergez, W.; Cavaro, M.; Paumel, K.; Jeannot, J. P.

    2015-07-01

    This study was carried out to understand the response of an eddy current type flowmeter in two phase liquid-metal flow. We use the technique of ellipse fit and correlate the fluctuations in the angle of inclination of this ellipse with the void fraction. The effects of physical parameters such as coil excitation frequency and flow velocity have been studied. The results show the possibility of using an eddy current flowmeter as a gas detector for large void fractions. (authors)

  3. Luminosity distance in ``Swiss cheese'' cosmology with randomized voids. II. Magnification probability distributions

    NASA Astrophysics Data System (ADS)

    Flanagan, Éanna É.; Kumar, Naresh; Wasserman, Ira; Vanderveld, R. Ali

    2012-01-01

    We study the fluctuations in luminosity distances due to gravitational lensing by large scale (≳35Mpc) structures, specifically voids and sheets. We use a simplified “Swiss cheese” model consisting of a ΛCDM Friedman-Robertson-Walker background in which a number of randomly distributed nonoverlapping spherical regions are replaced by mass-compensating comoving voids, each with a uniform density interior and a thin shell of matter on the surface. We compute the distribution of magnitude shifts using a variant of the method of Holz and Wald , which includes the effect of lensing shear. The standard deviation of this distribution is ˜0.027 magnitudes and the mean is ˜0.003 magnitudes for voids of radius 35 Mpc, sources at redshift zs=1.0, with the voids chosen so that 90% of the mass is on the shell today. The standard deviation varies from 0.005 to 0.06 magnitudes as we vary the void size, source redshift, and fraction of mass on the shells today. If the shell walls are given a finite thickness of ˜1Mpc, the standard deviation is reduced to ˜0.013 magnitudes. This standard deviation due to voids is a factor ˜3 smaller than that due to galaxy scale structures. We summarize our results in terms of a fitting formula that is accurate to ˜20%, and also build a simplified analytic model that reproduces our results to within ˜30%. Our model also allows us to explore the domain of validity of weak-lensing theory for voids. We find that for 35 Mpc voids, corrections to the dispersion due to lens-lens coupling are of order ˜4%, and corrections due to shear are ˜3%. Finally, we estimate the bias due to source-lens clustering in our model to be negligible.

  4. Novel thick-foam ferroelectret with engineered voids for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Luo, Z.; Shi, J.; Beeby, S. P.

    2016-11-01

    This work reports a novel thick-foam ferroelectret which is designed and engineered for energy harvesting applications. We fabricated this ferroelectret foam by mixing a chemical blowing agent with a polymer solution, then used heat treatment to activate the agent and create voids in the polymer foam. The dimensions of the foam, the density and size of voids can be well controlled in the fabrication process. Therefore, this ferroelectret can be engineered into optimized structure for energy harvesting applications.

  5. Joints, fissures, and voids in rhyolite welded ash-flow tuff at Teton damsite, Idaho

    USGS Publications Warehouse

    Prostka, Harold J.

    1977-01-01

    Several kinds of joints, fissures, and voids are present in densely welded rhyolite ash-flow tuff at Teton damsite. Older fissures and voids probably were formed in the ash-flow sheet during secondary flowage, which probably was caused by differential compaction or settling over irregular topography. The younger, more abundant fissures are mostly steep cooling joints that probably have been opened farther by horizontal tectonic extension and gravitational creep, perhaps aided by lateral stress relief.

  6. Observations of dwarfs in nearby voids: implications for galaxy formation and evolution

    NASA Astrophysics Data System (ADS)

    Pustilnik, Simon A.

    2016-10-01

    The intermediate results of the ongoing study of deep samples of ~200 galaxies residing in nearby voids, are presented. Their properties are probed via optical spectroscopy, ugri surface photometry, and HI 21-cm line measurements, with emphasis on their evolutionary status. We derive directly the hydrogen mass M(HI), the ratio M(HI)/LB and the evolutionary parameter gas-phase O/H. Their luminosities and integrated colours are used to derive stellar mass M* and the second evolutionary parameter - gas mass-fraction f g). The colours of the outer parts, typically representative of the galaxy oldest stellar population, are used to estimate the upper limits on time since the beginning of the main SF episode. We compare properties of void galaxies with those of the similar late-type galaxies in denser environments. Most of void galaxies show smaller O/H for their luminosity, in average by ~30\\%, indicating slower evolution. Besides, the fraction of ~10\\% of the whole void sample or ~30\\% of the least luminous void LSB dwarfs show the oxygen deficiency by a factor of 2-5. The majority of this group appear very gas-rich, with f g ~(95-99)%, while their outer parts appear rather blue, indicating the time of onset of the main star-formation episode of less than 1-4 Gyr. Such unevolved LSBD galaxies appear not rare among the smallest void objects, but turned out practically missed to date due to the strong observational selection effects. Our results evidense for unusual evolutionary properties of the sizable fraction of void galaxies, and thus, pose the task of better modelling of dwarf galaxy formation and evolution in voids.

  7. Cosmic Voids in the SDSS DR12 BOSS Galaxy Sample: The Alcock-Paczynski Test

    NASA Astrophysics Data System (ADS)

    Mao, Qingqing; Berlind, Andreas A.; Scherrer, Robert J.; Neyrinck, Mark C.; Scoccimarro, Román; Tinker, Jeremy L.; McBride, Cameron K.; Schneider, Donald P.

    2017-02-01

    We apply the Alcock–Paczyński (AP) test to stacked voids identified using the final data release (DR12) of the Baryon Oscillation Spectroscopic Survey (BOSS). We also use 1000 mock galaxy catalogs that match the geometry, density, and clustering properties of the BOSS sample in order to characterize the statistical uncertainties of our measurements and take into account systematic errors such as redshift space distortions. For both BOSS data and mock catalogs, we use the ZOBOV algorithm to identify voids, we stack together all voids with effective radii of 30{--}100 {h}-1 {Mpc} in the redshift range of 0.43–0.7, and we accurately measure the shape of the stacked voids. Our tests with the mock catalogs show that we measure the stacked void ellipticity with a statistical precision of 2.6%. The stacked voids in redshift space are slightly squashed along the line of sight, consistent with previous studies. We repeat this measurement of stacked void shape in the BOSS data, assuming several values of {{{Ω }}}{{m}} within the flat {{Λ }}{CDM} model, and we compare this to the mock catalogs in redshift space to perform the AP test. We obtain a constraint of {{{Ω }}}{{m}}={0.38}-0.15+0.18 at the 68% confidence level from the AP test. We discuss the sources of statistical and systematic noise that affect the constraining power of this method. In particular, we find that the measured ellipticity of stacked voids changes more weakly with cosmology than the standard AP prediction, leading to significantly weaker constraints. We discuss how constraints will improve in future surveys with larger volumes and densities.

  8. Quantitative analysis of voids in percolating structures in two-dimensional N-body simulations

    NASA Technical Reports Server (NTRS)

    Harrington, Patrick M.; Melott, Adrian L.; Shandarin, Sergei F.

    1993-01-01

    We present in this paper a quantitative method for defining void size in large-scale structure based on percolation threshold density. Beginning with two-dimensional gravitational clustering simulations smoothed to the threshold of nonlinearity, we perform percolation analysis to determine the large scale structure. The resulting objective definition of voids has a natural scaling property, is topologically interesting, and can be applied immediately to redshift surveys.

  9. Analysis of void formation in SHEBA II using S{sub N} and Monte Carlo codes

    SciTech Connect

    Walters, S.; Butterfield, K.; Dudziak, D.

    1994-12-31

    The purpose of this work was to evaluate the effect of the introduction of a void into a supercritical solution system. Calculations have indicated that the primary shutdown mechanism in the excursion of a solution is radiolytic gas formation. The density of a radiolytic gas varies directly with the local power density. As such, the complete evaluation of the quench mechanism requires detailed knowledge of the reactivity effect of voids as a function of position.

  10. Analytical Yield Criterion for an Anisotropic Material Containing Spherical Voids and Exhibiting Tension-Compression Asymmetry

    DTIC Science & Technology

    2011-11-01

    closed-form approximate yield criteria were obtained for both spherical and cylindrical voids. Numerical studies have been conducted to verify and...developed criterion for plastic anisotropic med- ia displaying strength–differential effects is assessed through com- parison with numerical results...element X, composed of a homogeneous rigid-plastic matrix and a traction-free void. The matrix material is described by a convex yield function u(r) in

  11. Where do `red and dead' early-type void galaxies come from?

    NASA Astrophysics Data System (ADS)

    Croton, Darren J.; Farrar, Glennys R.

    2008-06-01

    Void regions of the Universe offer a special environment for studying cosmology and galaxy formation, which may expose weaknesses in our understanding of these phenomena. Although galaxies in voids are observed to be predominately gas rich, star forming and blue, a subpopulation of bright-red void galaxies can also be found, whose star formation was shutdown long ago. Are the same processes that quench star formation in denser regions of the Universe also at work in voids? We compare the luminosity function of void galaxies in the 2dF Galaxy Redshift Survey, to those from a galaxy formation model built on the Millennium simulation. We show that a global star formation suppression mechanism in the form of low-luminosity `radio-mode' active galactic nuclei (AGN) heating is sufficient to reproduce the observed population of void early types. Radio-mode heating is environment independent other than its dependence on dark matter halo mass, where, above a critical mass threshold of approximately Mvir ~ 1012.5Msolar, gas cooling on to the galaxy is suppressed and star formation subsequently fades. In the Millennium simulation, the void halo mass function is shifted with respect to denser environments, but still maintains a high-mass tail above this critical threshold. In such void haloes, radio-mode heating remains efficient and red galaxies are found; collectively these galaxies match the observed space density without any modification to the model. Consequently, galaxies living in vastly different large-scale environments but hosted by haloes of similar mass are predicted to have similar properties, consistent with observations.

  12. 19 CFR 122.114 - Contents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Contents. 122.114 Section 122.114 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Transit Air Cargo Manifest (TACM) Procedures § 122.114 Contents. (a) Form duplicates original manifest. Each transit air...

  13. 19 CFR 122.114 - Contents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Contents. 122.114 Section 122.114 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Transit Air Cargo Manifest (TACM) Procedures § 122.114 Contents. (a) Form duplicates original manifest. Each transit air...

  14. 19 CFR 122.114 - Contents.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Contents. 122.114 Section 122.114 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Transit Air Cargo Manifest (TACM) Procedures § 122.114 Contents. (a) Form duplicates original manifest. Each transit air...

  15. 19 CFR 122.114 - Contents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Contents. 122.114 Section 122.114 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Transit Air Cargo Manifest (TACM) Procedures § 122.114 Contents. (a) Form duplicates original manifest. Each transit air...

  16. Total evaluation of in bundle void fraction measurement test of PWR fuel assembly

    SciTech Connect

    Hori, Keiichi; Miyazaki, Keiji; Akiyama, Yoshiei; Nishioka, Hiromasa; Takeda, Naoki

    1996-08-01

    Nuclear Power Engineering Corporation is performing the various proof or verification tests on safety and reliability of nuclear power plants under the sponsorship of the Ministry of International Trade and Industry. As one program of these Japanese national projects, an in bundle void fraction measurement test of a pressurized water reactor (PWR) fuel assembly was started in 1987 and finished at the end of 1994. The experiments were performed using the 5 x 5 square array rod bundle test sections. The rod bundle test section simulates the partial section and full length of a 17 x 17 type Japanese PWR fuel assembly. A distribution of subchannel averaged void fraction in a rod bundle test section was measured by the gamma-ray attenuation method using the stationary multi beam systems. The additional single channel test was performed to obtain the required information for the calibration of the rod bundle test data and the assessment of the void prediction method. Three test rod bundles were prepared to analyze an axial power distribution effect, an unheated rod effect, and a grid spacer effect. And, the obtained data were used for the assessment of the void prediction method relevant to the subchannel averaged void fraction of PWR fuel assemblies. This paper describes the outline of the experiments, the evaluation of the experimental data and the assessment of void prediction method.

  17. Could multiple voids explain the cosmic microwave background Cold Spot anomaly?

    SciTech Connect

    Naidoo, Krishna; Benoit-Levy, Aurelien; Lahav, Ofer

    2016-03-20

    Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a ≳ 3σ primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ~-50 mu K. In this model the central CS temperature lies at ~ 2σ but fails to explain the CS hot ring. An alternative multi-void model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multi-void scenarios) are removed. Furthermore, the CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.

  18. Could multiple voids explain the cosmic microwave background Cold Spot anomaly?

    DOE PAGES

    Naidoo, Krishna; Benoit-Levy, Aurelien; Lahav, Ofer

    2016-03-20

    Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a ≳ 3σ primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ~-50 mu K.more » In this model the central CS temperature lies at ~ 2σ but fails to explain the CS hot ring. An alternative multi-void model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multi-void scenarios) are removed. Furthermore, the CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.« less

  19. Electromigration induced Kirkendall void growth in Sn-3.5Ag/Cu solder joints

    SciTech Connect

    Jung, Yong; Yu, Jin

    2014-02-28

    Effects of electric current flow on the Kirkendall void formation at solder joints were investigated using Sn-3.5Ag/Cu joints specially designed to have localized nucleation of Kirkendall voids at the Cu{sub 3}Sn/Cu interface. Under the current density of 1 × 10{sup 4} A/cm{sup 2}, kinetics of Kirkendall void growth and intermetallic compound thickening were affected by the electromigration (EM), and both showed the polarity effect. Cu{sub 6}Sn{sub 5} showed a strong susceptibility to the polarity effect, while Cu{sub 3}Sn did not. The electromigration force induced additional tensile (or compressive) stress at the cathode (or anode), which accelerated (or decelerated) the void growth. From the measurements of the fraction of void at the Cu{sub 3}Sn/Cu interface on SEM micrographs and analysis of the kinetics of void growth, the magnitude of the local stress induced by EM was estimated to be 9 MPa at the anode and −7 MPa at the cathode.

  20. Flux trap void effects in the high-flux isotope reactor with curium targets

    SciTech Connect

    Rothrock, R.B.

    1990-06-01

    The reactivity effect of voids in the high-flux isotope reactor (HFIR) flux trap/target region has been reevaluated to determine the impact of the use of curium target material in lieu of the {sup 242}Pu targets originally used. The HFIR, located at the Oak Ridge National Laboratory (ORNL) and operated for the US Department of Energy by Martin Marietta Energy Systems, Inc., produces transplutonium elements for research and industrial purposes by irradiating target materials in a central flux trap region of intense thermal neutron flux. The target region void worth was extensively investigated during the HFIR nuclear design and critical experiments. Subsequently, as larger quantities of heavy elements became available, HFIR targets were fabricated from curium. This change substantially increased the amount of transplutonium isotopes present in the target during irradiation; it is therefore necessary to determine the impact on the target region void worth. Nuclear calculations of the target void worth were made using the two-dimensional transport code DORT. To benchmark the methods and data, flux trap void worth experiments performed during the HFIR start-up physics tests were calculated with the two-dimensional model for void worth measurements with and without the simulated target present in the flux trap.

  1. Fast and interrupted expansion in cyclic void growth in dusty plasma

    NASA Astrophysics Data System (ADS)

    van de Wetering, F. M. J. H.; Brooimans, R. J. C.; Nijdam, S.; Beckers, J.; Kroesen, G. M. W.

    2015-01-01

    Low-pressure acetylene plasmas are able to spontaneously form dust particles. This will result in a dense cloud of solid particles that is levitated in the plasma. The formed particles can grow up to micrometers. We observed a spontaneous interruption in the expansion of the so-called dust void. A dust void is a macroscopic region in the plasma that is free of nanoparticles. The phenomenon is periodical and reproducible. We refer to the expansion interruption as ‘hiccup’. The expanding void is an environment in which a new cycle of dust particle formation can start. At a certain moment in time, this cycle reaches the (sudden) coagulation phase and as a result the void will temporarily shrink. To substantiate this reasoning, the electron density is determined non-intrusively using microwave cavity resonance spectroscopy. Moreover, video imaging of laser light scattering of the dust particles provides their spatial distribution. The emission intensity of a single argon transition is measured similarly. Our results support the aforementioned hypothesis for what happens during the void hiccup. The void dynamics preceding the hiccup are modeled using a simple analytical model for the two dominant forces (ion drag and electric) working on a nanoparticle in a plasma. The model results qualitatively reproduce the measurements.

  2. Dislocation creation and void nucleation in FCC ductile metals under tensile loading: a general microscopic picture.

    PubMed

    Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

    2014-11-10

    Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

  3. Void-precipitate association during neutron irradiation of austenitic stainless steel

    SciTech Connect

    Pedraza, D.F.; Maziasz, P.J.

    1986-01-01

    Microstructural data has recently become available on a single heat of 316 stainless steel irradiated in EBR-II and HFIR, over a wide range of irradiation temperature (55 to 750/sup 0/C), dose (7 to 75 dpa), and helium generation rate (0.5 to 55 at. ppM He/dpa). Extensive information on precipitate compositions and characteristics are included. The data reveal several important relationships between the development of voids and precipitation. Precipitate associated voids dominate the swelling of (DO heat) 316 at 500 to 650 C from 8.4 to 36 dpa in EBR-II. Cold work (CW) or helium preinjection delay void formation in EBR-II. Higher helium generation in HFIR also delays void formation at 500 to 640/sup 0/C in SA 316 and CW DO heat 316. The delay persists in CW 316 at least to 61 dpa in HFIR, but abundant matrix and precipitate-associated voids form in SA after 47 dpa. In another heat of CW 316 (N-lot) irradiated in HFIR matrix and precipitate voids form readily after 22 to 44 dpa at 500 to 600/sup 0/C.

  4. The role of dislocations in the growth of nanosized voids in ductile failure of metals

    NASA Astrophysics Data System (ADS)

    Meyers, Marc A.; Traiviratana, Sirirat; Lubarda, V. A.; Benson, David J.; Bringa, Eduardo M.

    2009-02-01

    Dislocations are the most important element in our understanding of the mechanical response of metals. Their postulation in 1934 led to revolutionary advances in our ability to predict the mechanical behavior of materials. The authors recently advanced a dislocation mechanism for void growth in ductile metals. This paper reviews the analytical and atomistic calculations carried out in support of this model. The emission of shear dislocation loops, nucleated at the surface of nanosized voids, is responsible for the outward flux of matter, promoting void growth. This is a new paradigm in the initiation of void growth, which was attributed to convergent vacancy diffusion or to prismatic loops by others. The analytical treatment is based on the emission of a dislocation from a void in the plane along which the shear stresses are maximum. Molecular dynamics calculations performed for different orientations of the tensile axis show how the loops generate and expand outward. These loops involve the emission of partial dislocations and are the counterpart for voids of the Ashby geometrically necessary shear loops postulated for rigid particles. This process is demonstrated for bicrystalline and nanocrystalline copper.

  5. Morphology and Number Density of Voids in Hydrogenated Amorphous Silicon: An Ab Initio Study

    NASA Astrophysics Data System (ADS)

    Biswas, Parthapratim; Paudel, Durga; Atta-Fynn, Raymond; Drabold, David A.; Elliott, Stephen R.

    2017-02-01

    We present a first-principles study of the formation and structure of microvoids in device-quality models of hydrogenated amorphous silicon (a -Si ∶H ). Using a combination of classical metadynamics and first-principles density-functional calculations, which is capable of generating large a -Si ∶H models with a linear size of several nanometers and a realistic hydrogen distribution, we examine the morphology and compute the number density of microvoids at low and high concentrations of hydrogen. The results of our calculations are compared with experimental data from small-angle x-ray scattering and hydrogen and implanted-helium effusion measurements. Our study suggests that the number density of microvoids is of the order of (7 - 8 )×1018 cm-3 for device-quality models with (8-10)-at. % H, and which increases to (1 - 3 )×1019 cm-3 with an increase of hydrogen content to 18 at. %. We find the morphology of the microvoids to be highly complex with a radius of gyration varying from 2.7 to 5.0 Å for very large models. The spatial distributions of microvoids at low and high concentrations are strongly influenced by the presence of isolated and interconnected voids, respectively, which are consistent with the results from hydrogen and implanted-helium effusion measurements. The simulation methodology and results presented here have direct applications in large-scale modeling of a -Si ∶H /c -Si heterojunctions with intrinsic thin-layer technology for the development of next-generation silicon solar cells and resistive switching mechanisms in ultra-low-power nonvolatile memory devices, such as chalcogenide- or oxide-based conductive bridging random-access-memory devices.

  6. Influence of nickel and beryllium content on swelling behavior of copper irradiated with fast neutrons

    SciTech Connect

    Singh, B.N.; Garner, F.A.; Edwards, D.J.; Evans, J.H.

    1996-10-01

    In the 1970`s, the effects of nickel content on the evolution of dislocation microstructures and the formation and growth of voids in Cu-Ni alloys were studied using 1 MeV electrons in a high voltage electron microscope. The swelling rate was found to decrease rapidly with increasing nickel content. The decrease in the swelling rate was associated with a decreasing void growth rate with increasing nickel content at irradiation temperatures up to 450{degrees}C. At 500{degrees}C, both void size and swelling rate were found to peak at 1 and 2% Ni, respectively, and then to decrease rapidly with increasing nickel content. However, recent work has demonstrated that the swelling behavior of Cu-5%Ni irradiated with fission neutrons is very similar for that of pure copper. The present experiments were designed to investigate this apparent discrepancy.

  7. Cold-batter mincing of hot-boned and crust-frozen air-chilled turkey breast allows for reduced sodium content in protein gels.

    PubMed

    Lee, H C; Medellin-Lopez, M; Singh, P; Sansawat, T; Chin, K B; Kang, I

    2014-09-01

    The purpose of this research was to evaluate sodium reduction in the protein gels that were prepared with turkey breasts after hot boning (HB), quarter (¼) sectioning, crust-frozen air-chilling (CFAC), and cold temperature mincing. For each of 4 replications, 36 turkeys were slaughtered and eviscerated. One-half of the carcasses were randomly assigned to water immersion chilling for chill boning (CB), whereas the remaining carcasses were immediately HB and quarter-sectioned/crust-frozen air-chilled (HB-¼CFAC) in a freezing room (-12°C, 1.0 m/s). After deboning, CB fillets were conventionally minced, whereas HB-¼CFAC fillets were cold minced up to 27 min with 1 or 2% salt. From the beginning of mincing, the batter temperatures of HB-¼CFAC were lower (P < 0.05) than those of CB batters up to 12 and 21 min for 2 and 1% salts, respectively. Upon mincing, the batter pH of the HB-¼CFAC (P < 0.05) rapidly decreased and was not different (P > 0.05) from the pH of CB batters, except for the 1% salt HB-¼CFAC batter after 15 min of mincing. The pattern of pH was not changed when the batters were stored overnight. The protein of 2% salt HB-¼CFAC fillets was more extractable (P < 0.05) than that of CB fillets at 9, 12, 18, and 24 min. Similarly, the protein of 1% salt HB-¼CFAC fillets was more extractable (P < 0.05) than that of CB fillets from 12 min. Stress values of 2% salt HB-¼CFAC gels were higher (P < 0.05) than those of 1 and 2% salt CB gels, with intermediate values for 1% salt HB-¼CFAC gels. In the scanning electron microscope image, prerigor batter appears to have more open space, less protein aggregation, and more protein-coated fat particles than those of postrigor batters. Based on these results, the combination of HB-¼CFAC and cold-batter-mincing technologies appear to improve protein functionality and sodium reduction capacity.

  8. Void Evolution in Sub-100-Micron Sn-Ag Solder Bumps during Multi-reflow and Aging and its Effects on Bonding Reliability

    NASA Astrophysics Data System (ADS)

    Lin, Xiaoqin; Luo, Le

    2008-03-01

    The evolution of voids in the interfacial region of electroplated Sn-3.0Ag solder bumps on electroplated Cu and its effects on bonding reliability were studied. Results show that volume shrinkage resulted in void formation during multi-reflow, while the Kirkendall effect led to void formation during aging. A thick η-phase and voids at the boundaries among Cu6Sn5 grains promoted the void growth in the ɛ-phase. Though the formation of voids had a trivial weakening effect on the shear strength of the solder joints, the voids were a threat to the bonding reliability of solder bumps.

  9. An ultrasonic investigation of the effect of voids on the mechanical properties of bread dough and the role of gas cells in determining the cellular structure of freeze- dried breadcrumb

    NASA Astrophysics Data System (ADS)

    Elmehdi, Hussein Mohamed

    charge repulsion effects. In the second part of the thesis, freeze-dried breadcrumb structure was investigated. To change the size of the air cells, the dough was proofed for various times. Ultrasonic velocity and amplitude decrease with increasing φ. The experimental data were found to be in reasonable agreement with theoretical models for the elasticity of isotropic cellular foams and tortuosity. The effects of anisotropy in breadcrumb structure were studied by compressing samples uniaxially, thereby transforming the shape of the air cells from approximately spherical to elongated ellipsoids. Ultrasonic measurements were taken in the directions parallel and perpendicular to the strain. These results indicated that the path by which sound propagates is critical. The data were interpreted using the same two theoretical models, taking into account anisotropy effects. The tortuosity model was able to interpret the void fraction dependence of the velocity along the two orthogonal directions, thus giving a way of relating changes in ultrasonic velocity to changes in breadcrumb structure. This thesis demonstrates the potential for using ultrasound as a non-destructive, cheap and accurate tool for studying the effect of voids (and their expansion) on dough properties. These ultrasonic techniques can also be used to investigate the effect of air cells on the structural integrity of breadcrumb and hence be a useful tool for quantitatively assessing bread quality.

  10. Two-phase flow pattern recognition in a varying section based on void fraction and pressure measurements

    NASA Astrophysics Data System (ADS)

    de Kerret, F.; Benito, I.; Béguin, C.; Pelletier, D.; Etienne, S.

    2016-11-01

    In a hydroelectric turbine, the air injected during operation has an impact on the yield of the machine leading to important losses of energy. To understand those losses and be able to reduce them, a first step is to understand the pattern of the two-phase flows and describe their characteristics in the turbine. Those two-phase flows can be bubbly, intermittent, or annular, with different types of intermittent flow possible. Two-phase flow patterns are well defined in classical geometries such as cylinders with reliable descriptions available [5]. But, there is a critical lack of knowledge for flow patterns in other geometries. In our present work we take interest into a geometry that is a pipe with periodical changes of the section and realize a flow pattern map. To realize this map, we measure the pressure variations and void fraction fluctuations while changing the flow rates of water and air in our test section. We then use our physical understanding of the phenomena to analyze data and identify different flow patterns, characterize them, and build a new flow pattern map.

  11. Cohesive-zone laws for void growth — I. Experimental field projection of crack-tip crazing in glassy polymers

    NASA Astrophysics Data System (ADS)

    Hong, Soonsung; Chew, Huck Beng; Kim, Kyung-Suk

    2009-08-01

    A hybrid framework for inverse analysis of crack-tip cohesive-zone model is developed in this two-part paper to measure cohesive-zone laws of void growth in polymers by combining analytical, experimental, and numerical approaches. This paper focuses on experimental measurements of the cohesive-zone laws for two nonlinear fracture processes in glassy polymers, namely multiple crazing in crack-growth toughening of rubber-toughened high-impact polystyrene (HIPS) and crazing of steady-state crack growth in polymethylmethacrylate (PMMA) under a methanol environment. To this end, electronic speckle pattern interferometry (ESPI) is first applied to measure the crack-tip displacement fields surrounding the fracture process zones in these polymers. These fields are subsequently equilibrium smoothed and used in the extraction of the cohesive-zone laws via an analytical solution method of the inverse problem, the planar field projection method (P-FPM) [Hong, S., Kim, K.-S., 2003. Extraction of cohesive-zone laws from elastic far-fields of a cohesive crack tip: a field projection method. Journal of the Mechanics and Physics of Solids 51, 1267-1286]. Results show that the proposed framework of the P-FPM could provide a systematic way of finding the shape of the cohesive-zone laws governed by the different micro-mechanisms in the fracture processes. In HIPS, inter-particle multiple crazing develops and the craze zone broadens ahead of a crack-tip under mechanical loading. The corresponding cohesive-zone relationship of the multiple-craze zone is found to be highly convex, which indicates effectiveness of rubber particle toughening. It is also observed that the effective peak traction, 7 MPa, in the crack-tip cohesive zone of HIPS (30% rubber content) is lower than the uniaxial yield stress of 9 MPa, presumably due to stress multi-axiality effects. In contrast, in PMMA, methanol localizes the crack-tip craze, weakening the craze traction for craze-void initiation to about 9 MPa

  12. Method for controlling void fraction distribution in an in situ oil shale retort

    SciTech Connect

    Ricketts, T.E.

    1984-04-17

    A method for forming an in situ oil shale retort in a retort site in a subterranean formation is provided. The in situ oil shale retort contains a fragmented permeable mass of oil shale particles formed within top, bottom, and side boundaries of the retort site. At least one void is excavated in the subterranean formation within the boundaries of the retort site, while a zone of unfragmented formation is left within the boundaries of the retort site adjacent such a void. An inlet is formed in a zone of the retort adjacent the intersection of a first side boundary of the retort site and the top boundary of the retort site and an outlet is formed in a zone of the retort adjacent the intersection of a second side boundary of the retort site and the bottom boundary of the retort site. The second side boundary is on the opposite side of the retort site from the first side boundary. An array of explosive charges is formed in the zone of unfragmented formation and the charges are detonated for explosively expanding the zone of formation toward the void for forming the fragmented mass within the boundaries of the retort site. The explosive charge pattern and detonation sequence are provided so that the fragmented mass formed has a lower void fraction in a center region of the retort and a higher void fraction in regions of the retort adjacent the side boundaries.

  13. Void asymmetries in the cosmic web: a mechanism for bulk flows

    NASA Astrophysics Data System (ADS)

    Bland-Hawthorn, J.; Sharma, S.

    2016-10-01

    Bulk flows of galaxies moving with respect to the cosmic microwave background are well established observationally and seen in the most recent ΛCDM simulations. With the aid of an idealised Gadget-2 simulation, we show that void asymmetries in the cosmic web can exacerbate local bulk flows of galaxies. The {\\it Cosmicflows-2} survey, which has mapped in detail the 3D structure of the Local Universe, reveals that the Local Group resides in a ``local sheet'' of galaxies that borders a ``local void'' with a diameter of about 40 Mpc. The void is emptying out at a rate of 16 km s-1 Mpc-1. In a co-moving frame, the Local Sheet is found to be moving away from the Local Void at ~ 260 km s-1. Our model shows how asymmetric collapse due to unbalanced voids on either side of a developing sheet or wall can lead to a systematic movement of the sheet. We conjectured that asymmetries could lead to a large-scale separation of dark matter and baryons, thereby driving a dependence of galaxy properties with environment, but we do {\\it not} find any evidence for this effect.

  14. Adhesion of voids to bimetal interfaces with non-uniform energies.

    PubMed

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; Wang, Yongqiang; Demkowicz, Michael J; Beyerlein, Irene J; Mara, Nathan A

    2015-10-21

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. This work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.

  15. A possible cold imprint of voids on the microwave background radiation

    SciTech Connect

    Cai, Yan-Chuan; Cole, Shaun; Frenk, Carlos S.; Neyrinck, Mark C.; Szapudi, István

    2014-05-10

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z < 0.44. We find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat filter scaled to the radius of each void, we assess the statistical significance of the imprint at ∼2σ, and we make crucial use of N-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radii. We have found that the same filter radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal has a much higher amplitude than expected from ISW in the concordance ΛCDM universe. The discrepancy is also at the ∼2σ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

  16. The void spectrum in two-dimensional numerical simulations of gravitational clustering

    NASA Technical Reports Server (NTRS)

    Kauffmann, Guinevere; Melott, Adrian L.

    1992-01-01

    An algorithm for deriving a spectrum of void sizes from two-dimensional high-resolution numerical simulations of gravitational clustering is tested, and it is verified that it produces the correct results where those results can be anticipated. The method is used to study the growth of voids as clustering proceeds. It is found that the most stable indicator of the characteristic void 'size' in the simulations is the mean fractional area covered by voids of diameter d, in a density field smoothed at its correlation length. Very accurate scaling behavior is found in power-law numerical models as they evolve. Eventually, this scaling breaks down as the nonlinearity reaches larger scales. It is shown that this breakdown is a manifestation of the undesirable effect of boundary conditions on simulations, even with the very large dynamic range possible here. A simple criterion is suggested for deciding when simulations with modest large-scale power may systematically underestimate the frequency of larger voids.

  17. Adhesion of voids to bimetal interfaces with non-uniform energies

    PubMed Central

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; Wang, Yongqiang; Demkowicz, Michael J.; Beyerlein, Irene J.; Mara, Nathan A.

    2015-01-01

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. This work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces. PMID:26486278

  18. Critical velocities for deflagration and detonation triggered by voids in a REBO high explosive

    SciTech Connect

    Herring, Stuart Davis; Germann, Timothy C; Jensen, Niels G

    2010-01-01

    The effects of circular voids on the shock sensitivity of a two-dimensional model high explosive crystal are considered. We simulate a piston impact using molecular dynamics simulations with a Reactive Empirical Bond Order (REBO) model potential for a sub-micron, sub-ns exothermic reaction in a diatomic molecular solid. The probability of initiating chemical reactions is found to rise more suddenly with increasing piston velocity for larger voids that collapse more deterministically. A void with radius as small as 10 nm reduces the minimum initiating velocity by a factor of 4. The transition at larger velocities to detonation is studied in a micron-long sample with a single void (and its periodic images). The reaction yield during the shock traversal increases rapidly with velocity, then becomes a prompt, reliable detonation. A void of radius 2.5 nm reduces the critical velocity by 10% from the perfect crystal. A Pop plot of the time-to-detonation at higher velocities shows a characteristic pressure dependence.

  19. Improved linear kinetic Sunyaev-Zel'dovich effect constraints on the observed Local Void

    NASA Astrophysics Data System (ADS)

    Hoscheit, Benjamin L.; Barger, Amy J.

    2017-01-01

    A class of large, gigaparsec (Gpc)-scale local void models has been ruled out by linear kinetic Sunyaev-Zel'dovich (kSZ) effect constraints from the South Pole Telescope and the Atacama Cosmology Telescope. However, there is substantial and growing observational evidence from the normalized luminosity density in the near-infrared that the local universe may be under-dense on scales of several hundred Megaparsecs. Theoretically, a small void model would relieve tension in observational challenges to the standard Friedmann-Lemaître-Robertson-Walker (FLRW) cosmological model. Thus, we decided to test whether a small void described by a parameterization of the observational data could be ruled out by the latest linear kSZ constraints. Instead, we find that the previous linear kSZ constraints as well as new ones from the South Pole Telescope are fully compatible with the existence of a small void of the size suggested by the luminosity density observations. The presence of such a void could have cosmologically significant implications.

  20. Adhesion of voids to bimetal interfaces with non-uniform energies

    SciTech Connect

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; Wang, Yongqiang; Demkowicz, Michael J.; Beyerlein, Irene J.; Mara, Nathan A.

    2015-10-21

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. Ultimately, this work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.

  1. Adhesion of voids to bimetal interfaces with non-uniform energies

    DOE PAGES

    Zheng, Shijian; Shao, Shuai; Zhang, Jian; ...

    2015-10-21

    Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore,more » because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. Ultimately, this work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.« less

  2. A sequential comparison of postoperative voiding function between two different transobturator sling procedures

    PubMed Central

    Choi, Don Kyoung; Jung, Ha Bum; Lee, Young Goo; Kim, Ki Kyung; Cho, Sung Tae

    2016-01-01

    Introduction We evaluated sequential postoperative voiding function of two types of sling procedures (Monarc® and ALIGN®) in patients with stress urinary incontinence. Methods Ninety-one women diagnosed with urodynamic stress incontinence were randomly assigned to the study. All enrolled patients underwent Monarc or ALIGN procedure. They were postoperatively evaluated at one day, one week, one month, three months, 12 months, and 24 months. The voiding function was evaluated with uroflowmetry and post-void residual urine. Patients were asked if voiding had changed after surgery and had to complete the incontinence quality of life scale (I-QoL) questionnaire at 12 months. Results The Monarc (n=47) and ALIGN (n=44) groups had similar demographic characteristics. The maximal flow rate (Qmax) was significantly decreased on the first day after surgery and gradually increased during the following weeks. Comparing the two groups at one week, the ALIGN group had a significantly decreased Qmax than the Monarc group (17.6 ± 5.2 vs. 20.7 ± 5.0; p=0.004). However, at one, three, 12, and 24 months, there were no significant differences between the two groups. Conclusions This study demonstrated that an absorbable tensioning suture in the Monarc mesh could increase Qmax compared to ALIGN at one week after surgery. An absorbable tensioning suture may reduce the risk of an early postoperative voiding dysfunction compared to other meshes that do not have this. PMID:28096921

  3. Searching for Dwarf H Alpha Emission-line Galaxies within Voids III: First Spectra

    NASA Astrophysics Data System (ADS)

    Moody, J. Ward; Draper, Christian; McNeil, Stephen; Joner, Michael D.

    2017-02-01

    The presence or absence of dwarf galaxies with {M}r\\prime > -14 in low-density voids is determined by the nature of dark matter halos. To better understand what this nature is, we are conducting an imaging survey through redshifted Hα filters to look for emission-line dwarf galaxies in the centers of two nearby galaxy voids called FN2 and FN8. Either finding such dwarfs or establishing that they are not present is a significant result. As an important step in establishing the robustness of the search technique, we have observed six candidates from the survey of FN8 with the Gillett Gemini telescope and GMOS spectrometer. All of these candidates had emission, although none was Hα. The emission in two objects was the [O iii]λ4959, 5007 doublet plus Hβ, and the emission in the remaining four was the [O ii]λ3727 doublet, all from objects beyond the void. While no objects were within the void, these spectra show that the survey is capable of finding emission-line dwarfs in the void centers that are as faint as {M}r\\prime ∼ -12.4, should they be present. These spectra also show that redshifts estimated from our filtered images are accurate to several hundred km s‑1 if the line is identified correctly, encouraging further work in finding ways to conduct redshift surveys through imaging alone.

  4. An Extended Self-Consistent Viscoplastic Polycrystal Formulation: Application to Polycrystals with Voids

    SciTech Connect

    Lebensohn, Ricardo A.; Tomé, Carlos N.; Maudlin, Paul J.

    2003-08-01

    In this work we consider the presence of ellipsoidal voids inside polycrystals submitted to large strain deformation. For this purpose, the originally incompressible viscoplastic self-consistent (VPSC) formulation of Lebensohn and Tomé (1993) has been extended to compressible polycrystals. In doing this, both the deviatoric and the spherical components of strain rate and stress are accounted for. Such an extended model allows us to account for the presence of voids and for porosity evolution, while preserving the anisotropy and crystallographic capabilities of the VPSC model. The formulation is adjusted to match Gurson model in the limit of rateindependent isotropic media and spherical voids. We present several applications of this extended VPSC model that address the coupling between texture, plastic anisotropy, void shape, triaxiality, and porosity evolution. This report contains a detailed and comprehensive derivation of the VPSC polycrystal model and of the equations associated with the theory. Such description is meant to serve as a general reference source for the VPSC formulation and is not limited to the particular case of voided polycrystals.

  5. Newtonian self-gravitating system in a relativistic huge void universe model

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ryusuke; Nakao, Ken-ichi; Yoo, Chul-Moon

    2016-12-01

    We consider a test of the Copernican Principle through observations of the large-scale structures, and for this purpose we study the self-gravitating system in a relativistic huge void universe model which does not invoke the Copernican Principle. If we focus on the the weakly self-gravitating and slowly evolving system whose spatial extent is much smaller than the scale of the cosmological horizon in the homogeneous and isotropic background universe model, the cosmological Newtonian approximation is available. Also in the huge void universe model, the same kind of approximation as the cosmological Newtonian approximation is available for the analysis of the perturbations contained in a region whose spatial size is much smaller than the scale of the huge void: the effects of the huge void are taken into account in a perturbative manner by using the Fermi-normal coordinates. By using this approximation, we derive the equations of motion for the weakly self-gravitating perturbations whose elements have relative velocities much smaller than the speed of light, and show the derived equations can be significantly different from those in the homogeneous and isotropic universe model, due to the anisotropic volume expansion in the huge void. We linearize the derived equations of motion and solve them. The solutions show that the behaviors of linear density perturbations are very different from those in the homogeneous and isotropic universe model.

  6. Void fraction measurement in subcooled forced convective boiling with refrigerant 12

    SciTech Connect

    Stangl, G.; Mayinger, F. )

    1990-01-01

    This article presents investigations and results of void fraction and pressure drop of dichlordifluomethane (CCl{sub 2}F{sub 2}) in forced convective, subcooled boiling. The data were taken at different heat fluxes in a 12- to 25-bar pressure range, the mass fluxes have been varied from 500 to 3000 kg/m{sup 2}s with an inlet subcooling in the range from 10 to 50 K. The experiments have been conducted in an annular test channel with a 0.016-m inner diameter and a 0.03-m outer diameter. The inner tube of the annulus was heated by direct current. The void fraction data were gauged with a {gamma}-densitometer and a specially designed impedance void meter. The experimental results reveal that the void fraction is nearly constant from the onset of nucleation boiling to subcooling of about {Delta}T = 10 K. A method for predicting the void fraction based on the drift flux model is presented.

  7. Air oxidation of hydrazine. 1. Reaction kinetics on natural kaolinites, halloysites, and model substituent layers with varying iron and titanium oxide and O- center contents

    NASA Technical Reports Server (NTRS)

    Coyne, L.; Mariner, R.; Rice, A.

    1991-01-01

    Air oxidation of hydrazine was studied by using a group of kaolinites, halloysites, and substituent oxides as models for the tetrahedral and octahedral sheets. The rate was found to be linear with oxygen. The stoichiometry showed that oxygen was the primary oxidant and that dinitrogen was the only important nitrogen-containing product. The rates on kaolinites were strongly inhibited by water. Those on three-dimensional silica and gibbsite appeared not to be. That on a supposedly layered silica formed from a natural kaolinite by acid leaching showed transitional behavior--slowed relative to that expected from a second-order reaction relative to that on the gibbsite and silica but faster than those on the kaolinites. The most striking result of the reaction was the marked increase in the rate of reaction of a constant amount of hydrazine as the amount of clay was increased. The increase was apparent (in spite of the water inhibition at high conversions) over a 2 order of magnitude variation of the clay weight. The weight dependence was taken to indicate that the role of the clay is very important, that the number of reactive centers is very small, or that they may be deactivated over the course of the reaction. In contrast to the strong dependence on overall amount of clay, the variation of amounts of putative oxidizing centers, such as structural Fe(III), admixed TiO2 or Fe2O3, or O- centers, did not result in alteration of the rate commensurate with the degree of variation of the entity in question. Surface iron does play some role, however, as samples that were pretreated with a reducing agent were less active as catalysts than the parent material. These results were taken to indicate either that the various centers interact to such a degree that they cannot be considered independently or that the reaction might proceed by way of surface complexation, rather than single electron transfers.

  8. Radiological assessment of water treatment processes in a water treatment plant in Saudi Arabia: Water and sludge radium content, radon air concentrations and dose rates.

    PubMed

    Al-Jaseem, Q Kh; Almasoud, Fahad I; Ababneh, Anas M; Al-Hobaib, A S

    2016-09-01

    There is an increase demand for clean water sources in Saudi Arabia and, yet, renewable water resources are very limited. This has forced the authorities to explore deep groundwater which is known to contain large concentrations of radionuclides, mainly radium isotopes. Lately, there has been an increase in the number of water treatment plants (WTPs) around the country. In this study, a radiological assessment of a WTP in Saudi Arabia was performed. Raw water was found to have total radium activity of 0.23Bq/L, which exceeds the international limit of 0.185Bq/L (5pCi/L). The WTP investigated uses three stages of treatment: flocculation/sedimentation, sand filtration and reverse osmosis. The radium removal efficiency was evaluated for each stage and the respective values were 33%, 22% and 98%. Moreover, the activity of radium in the solid waste generated from the WTP in the sedimentation and sand filtrations stages were measured and found to be 4490 and 6750Bq/kg, respectively, which exceed the national limit of 1000Bq/kg for radioactive waste. A radiological assessment of the air inside the WTP was also performed by measuring the radon concentrations and dose rates and were found in the ranges of 2-18Bq/m(3) and 70-1000nSv/h, respectively. The annual effective dose was calculated and the average values was found to be 0.3mSv which is below the 1mSv limit.

  9. ''The Incubation Period for Void Swelling and its Dependence on Temperature, Dose Rate, and Dislocation Structure Evolution''

    SciTech Connect

    Surh, M P; Sturgeon, J B; Wolfer, W G

    2002-06-13

    Void swelling in structural materials used for nuclear reactors is characterized by an incubation period whose duration largely determines the usefulness of the material for core components. Significant evolution of the dislocation and void microstructures that control radiation-induced swelling can occur during this period. Thus, a theory of incubation must treat time-dependent void nucleation in combination with dislocation evolution, in which the sink strengths of voids and dislocations change in concert. We present theoretical results for void nucleation and growth including the time-dependent, self-consistent coupling of point defect concentrations to the evolution of both void populations and dislocation density. Simulations show that the incubation radiation dose is a strong function of the starting dislocation density and of the dislocation bias factors for vacancy and interstitial absorption. Irradiation dose rate and temperature also affect the duration of incubation. The results are in general agreement with experiment for high purity metals.

  10. Calidad del aire interior

    EPA Pesticide Factsheets

    This web site will educate the public about indoor environmental issues including health risks and means by which human exposures can be reduced. Content on this site will be focused on Spanish translated resources for information about indoor air quality.

  11. The coupled effect of fiber volume fraction and void fraction on hydraulic fluid absorption of quartz/BMI laminates

    NASA Astrophysics Data System (ADS)

    Hurdelbrink, Keith R.; Anderson, Jacob P.; Siddique, Zahed; Altan, M. Cengiz

    2016-03-01

    Bismaleimide (BMI) resin with quartz (AQ581) fiber reinforcement is a composite material frequently used in aerospace applications, such as engine cowlings and radomes. Various composite components used in aircrafts are exposed to different types of hydraulic fluids, which may lead to anomalous absorption behavior over the service life of the composite. Accurate predictive models for absorption of liquid penetrants are particularly important as the composite components are often exposed to long-term degradation due to absorbed moisture, hydraulic fluids, or similar liquid penetrants. Microstructural features such as fiber volume fraction and void fraction can have a significant effect on the absorption behavior of fiber-reinforced composites. In this paper, hydraulic fluid absorption characteristics of quartz/BMI laminates fabricated from prepregs preconditioned at different relative humidity and subsequently cured at different pressures are presented. The composite samples are immersed into hydraulic fluid at room temperature, and were not subjected to any prior degradation. To generate process-induced microvoids, prepregs were conditioned in an environmental chamber at 2% or 99% relative humidity at room temperature for a period of 24 hours prior to laminate fabrication. To alter the fiber volume fraction, the laminates were fabricated at cure pressures of 68.9 kPa (10 psi) or 482.6 kPa (70 psi) via a hot-press. The laminates are shown to have different levels of microvoids and fiber volume fractions, which were observed to affect the absorption dynamics considerably and exhibited clear non-Fickian behavior. A one-dimensional hindered diffusion model (HDM) was shown to be successful in predicting the hydraulic fluid absorption. Model prediction indicates that as the fabrication pressure increased from 68.9 kPa to 482.6 kPa, the maximum fluid content (M∞) decreased from 8.0% wt. to 1.0% wt. The degree of non-Fickian behavior, measured by hindrance coefficient (

  12. Factors affecting the pheromone composition of voided boar saliva.

    PubMed

    Booth, W D

    1987-11-01

    The pheromone binding protein 'pheromaxein' which binds the pheromonal 16-androstene steroids in the saliva of the male pig (boar), was degraded and lost its binding activity in saliva incubated in air for 72 h at 21 degrees C and 37 degrees C. However, pheromaxein and its binding activity were retained in saliva incubated for 168 h at 4 degrees C. When the 3H-labelled pheromones 5 alpha-androst-16-en-3 alpha-ol (3 alpha-androstenol), 5 alpha-androst-16-en-3-one (5 alpha-androstenone) and 5 alpha-androst-16-en-3 beta-ol (3 beta-androstenol) were incubated with boar saliva for 168 h at 21 degrees C, 3 alpha-androstenol was primarily converted to 5 alpha-androstenone and 5 alpha-androstenone to 3 beta-androstenol; 3 beta-androstenol was unchanged. Evidence was obtained for microorganisms being responsible for these steroid transformations.

  13. Irradiation-induced nano-voids in strained tin precipitates in silicon

    NASA Astrophysics Data System (ADS)

    Gaiduk, P. I.; Lundsgaard Hansen, J.; Nylandsted Larsen, A.

    2014-04-01

    We report on self-assembling of spherically shaped voids in nanometer size strained Sn precipitates after irradiation with He+ ions in different conditions. It is found that high-temperature irradiation induces vacancies which are collected by compressively strained Sn precipitates enhancing of out-diffusion of Sn atoms from the precipitates. Nano-voids formation takes place simultaneously with a β- to α-phase transformation in the Sn precipitates. Post-irradiation thermal treatment leads to the removal of voids and a backward transformation of the Sn phase to β-phase. Strain-enhanced separation of point defects along with vacancy assisted Sn out-diffusion and precipitate dissolution are discussed.

  14. Void growth in high strength aluminium alloy single crystals: a CPFEM based study

    NASA Astrophysics Data System (ADS)

    Asim, Umair; Siddiq, M. Amir; Demiral, Murat

    2017-04-01

    High strength aluminium alloys that are produced through forming and joining processes are widely used in aerospace components. The ductile failure in these metals occurs due to the evolution and accumulation of microscopic defects, such as microvoids and shear bands. The present work investigates the underlying physical mechanisms during ductile failure by performing a rigorous, fully-validated, three-dimensional crystal plasticity, finite element study with aluminium alloy single crystals. Representative volume element (RVE) based simulations of single crystalline aluminium alloys (AA-5xxx) with different void geometries and orientations have been performed. Both local and nonlocal crystal plasticity constitutive models have been implemented in a finite element framework and are used to seek new insights into the interrelationships among void growth, initial porosity, initial void size, plastic anisotropy, and local/nonlocal size effects.

  15. Pressure drops during low void volume combustion retorting of oil shale

    SciTech Connect

    McLendon, T.R.

    1986-01-01

    Stacks of cut oil shale bricks were combustion retorted in a batch, pilot scale sized retort at low void volumes (overall voids ranged from 8.4% to 18.4%). Retort pressure drops increased during retorting at least one order of magnitude. The Ergun equation and Darcy's law have been used by several researchers and organizations as diagnostic tools on oil shale retorts. These equations were tested on the uniformly packed retort reported in this paper to evaluate how well the equations represented the experimental conditions. Use of the Ergun equation to estimate the average particle size from retort pressure drops gave answers that were only approximately correct. Calculation of retort pressure drops from Darcy's law during retorting at low void volumes will probably give answers that are several times too small. Thermal expansion of the shale during retorting decreases retort permeability greatly and calculation of the decreased permeability is not possible at the present level of technology.

  16. Improving adsorption cryocoolers by multi-stage compression and reducing void volume

    NASA Technical Reports Server (NTRS)

    Bard, S.

    1986-01-01

    It is shown that the performance of gas adsorption cryocoolers is greatly improved by using adsorbents with low void volume within and between individual adsorbent particles (reducing void volumes in plumbing lines), and by compressing the working fluid in more than one stage. Refrigerator specific power requirements and compressor volumetric efficiencies are obtained in terms of adsorbent and plumbing line void volumes and operating pressures for various charcoal adsorbents using an analytical model. Performance optimization curves for 117.5 and 80 K charcoal/nitrogen adsorption cryocoolers are given for both single stage and multistage compressor systems, and compressing the nitrogen in two stages is shown to lower the specific power requirements by 18 percent for the 117.5 K system.

  17. Piezochromic Phenomena of Nanometer Voids Formed by Mono-Dispersed Nanometer Powders Compacting Process

    PubMed Central

    Su, Lihong; Wan, Caixia; Zhou, Jianren; Wang, Yiguang; Wang, Liang; Ai, Yanling; Zhao, Xu

    2013-01-01

    Piezochromism describes a tendency of certain materials changing colors when they are subjected to various pressure levels. It occurs particularly in some polymers or inorganic materials, such as in palladium complexes. However, piezochromism is generally believed to work at high pressure range of 0.1–10 GPa. This research work focused on unique piezochromism responses of the nanometer voids formed by the 5–20 nm inorganic ISOH nanometer powders. It was discovered that microstructures of the nanometer voids could change color at very low pressures of only 0.002–0.01 GPa; its sensitivity to pressure was increased by tens of times. It is believed that the uniform microstructures of nanometer powders contributed to the material's high sensitivity of piezochromic phenomena. One factor which quantum optical change caused by nanometer voids affected the quantum confinement effect; another is surface Plasmon Resonance of great difference dielectric property between conductive ITO powder and insulation hydroxide. PMID:24115999

  18. Influence of void fraction in the power distribution for a GE-12 fuel assembly

    NASA Astrophysics Data System (ADS)

    Castillo, S. J.; Vargas, G. A.; del Valle Gallegos, E.

    2017-01-01

    Analysis of the influence of void fraction distribution is very important to learn about the fission process and heat produced by the fuel assembly, here in this study several void fraction (VF) values along different burnup values have been considered in order to observe their influence in power distribution, uranium consumption, neutron flux andbehaviour for a GE-12 fuel assembly. For this study, burnups up to 60 MWd/kg and VF values up to 0.8 were considered setting the uranium enrichment at 3.5 weight percent at the start of every VF scenario, results show that higher void fractions reduce the thermal flux decreasing thermal fission and limiting heat production.

  19. Effect of irradiation temperature on void swelling of China Low Activation Martensitic steel (CLAM)

    SciTech Connect

    Zhao Fei; Qiao Jiansheng; Huang Yina; Wan Farong Ohnuki, Soumei

    2008-03-15

    CLAM is one composition of a Reduced Activation Ferritic/Martensitic steel (RAFM), which is being studied in a number of institutes and universities in China. The effect of electron-beam irradiation temperature on irradiation swelling of CLAM was investigated by using a 1250 kV High Voltage Electron Microscope (HVEM). In-situ microstructural observations indicated that voids formed at each experimental temperature - 723 K, 773 K and 823 K. The size and number density of voids increased with increasing irradiation dose at each temperature. The results show that CLAM has good swelling resistance. The maximum void swelling was produced at 723 K; the swelling was about 0.3% when the irradiation damage was 13.8 dpa.

  20. External estimate of the yield surface of an arbitrary ellipsoid containing a confocal void

    NASA Astrophysics Data System (ADS)

    Leblond, Jean-Baptiste; Gologanu, Mihai

    2008-11-01

    This work provides an external estimate, based on limit-analysis, of the yield surface of an arbitrary (non-spheroidal) ellipsoid made of ideal-plastic von Mises material and containing a confocal ellipsoidal void, under conditions of homogeneous boundary strain rate. The upper estimate of the overall plastic dissipation is based on consideration of incompressible velocity fields satisfying conditions of homogeneous strain rate on all ellipsoids confocal with the void and the outer boundary. One establishes the existence, uniqueness and explicit expression of such a velocity field for every overall strain rate tensor imposed on this boundary. The estimate of the overall plastic dissipation obtained may be used either as a rigorous upper bound, to assess the quality of existing models for the overall behavior of porous ductile materials containing ellipsoidal voids, or as an approximation helpful in the development of new such models. To cite this article: J.-B. Leblond, M. Gologanu, C. R. Mecanique 336 (2008).

  1. Quantification of void pinning effects during grain growth of nanocrystalline iron

    NASA Astrophysics Data System (ADS)

    Vetterick, G. A.; El-Atwani, O.; Baldwin, J. Kevin; Tonks, M. R.; Taheri, M. L.

    2016-12-01

    In-situ transmission electron microscopy (TEM) annealing experiments, coupled with an analytical model, compared void pinning effects in nanocrystalline Fe films during grain growth. Voided grain boundaries were shown to have nearly four orders of magnitude less grain boundary mobility than void-free grain boundaries. However the coverage of the grain boundaries by pores was over three times that which would be required for static particles to completely halt grain boundary migration. Grain boundary migration continued because the pores were dragged by the grain boundaries and continued to evolve and coalesce. Thus, pores can slow grain boundary migration but are not an effective means of fully stabilizing nanocrystalline grain size at high temperatures.

  2. Irradiation-induced nano-voids in strained tin precipitates in silicon

    SciTech Connect

    Gaiduk, P. I.; Lundsgaard Hansen, J. Nylandsted Larsen, A.

    2014-04-14

    We report on self-assembling of spherically shaped voids in nanometer size strained Sn precipitates after irradiation with He{sup +} ions in different conditions. It is found that high-temperature irradiation induces vacancies which are collected by compressively strained Sn precipitates enhancing of out-diffusion of Sn atoms from the precipitates. Nano-voids formation takes place simultaneously with a β- to α-phase transformation in the Sn precipitates. Post-irradiation thermal treatment leads to the removal of voids and a backward transformation of the Sn phase to β-phase. Strain-enhanced separation of point defects along with vacancy assisted Sn out-diffusion and precipitate dissolution are discussed.

  3. A Visual Basic program for analyzing oedometer test results and evaluating intergranular void ratio

    NASA Astrophysics Data System (ADS)

    Monkul, M. Murat; Önal, Okan

    2006-06-01

    A visual basic program (POCI) is proposed and explained in order to analyze oedometer test results. Oedometer test results have vital importance from geotechnical point of view, since settlement requirements usually control the design of foundations. The software POCI is developed in order perform the necessary calculations for convential oedometer test. The change of global void ratio and stress-strain characteristics can be observed both numerically and graphically. It enables the users to calculate some parameters such as coefficient of consolidation, compression index, recompression index, and preconsolidation pressure depending on the type and stress history of the soil. Moreover, it adopts the concept of intergranular void ratio which may be important especially in the compression behavior of sandy soils. POCI shows the variation of intergranular void ratio and also enables the users to calculate granular compression index.

  4. A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels.

    PubMed

    Li, Huajun; Ji, Haifeng; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing; Wu, Guohua

    2016-01-27

    Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers' works.

  5. 3D modeling of void nucleation and initial void growth due to Tin diffusion as a result of electromigration in polycrystalline lead-free solders

    NASA Astrophysics Data System (ADS)

    Karunakaran, Deepak

    Electromigration (EM) has been a serious reliability concern in microelectronics packaging for close to half a century now. Whenever the challenges of EM are overcome newer complications arise such as the demand for better performance due to increased miniaturization of semiconductor devices or the problems faced due to undesirable properties of lead-free solders. The motivation for the work is that there exists no fully computational modeling study on EM damage in lead-free solders (and also in lead-based solders). Modeling techniques such as one developed here can give new insights on effects of different grain features and offer high flexibility in varying parameters and study the corresponding effects. In this work, a new computational approach has been developed to study void nucleation and initial void growth in solders due to metal atom diffusion. It involves the creation of a 3D stochastic mesoscale model of the microstructure of a polycrystalline Tin structure. The next step was to identify regions of current crowding or 'hot-spots'. This was done through solving a finite difference scheme on top of the 3D structure. The nucleation of voids due to atomic diffusion from the regions of current crowding was modeled by diffusion from the identified hot-spot through a rejection free kinetic Monte-Carlo scheme. This resulted in the net movement of atoms from the cathode to the anode. The above steps of identifying the hotspot and diffusing the atoms at the hotspot were repeated and this lead to the initial growth of the void. This procedure was studied varying different grain parameters. In the future, the goal is to explore the effect of more grain parameters and consider other mechanisms of failure such as the formation of intermetallic compounds due to interstitial diffusion and dissolution of underbump metallurgy.

  6. Development and validation of advanced CFD models for detailed predictions of void distribution in a BWR bundle

    NASA Astrophysics Data System (ADS)

    Neykov, Boyan

    In recent years, a commonly adopted approach is to use Computational Fluid Dynamics (CFD) codes as computational tools for simulation of different aspects of the nuclear reactor thermal-hydraulic performance where high-resolution and high-fidelity modeling is needed. Within the framework of this PhD work, the CFD code STAR-CD [1] is used for investigations of two phase flow in air-water systems as well as boiling phenomena in simple pipe geometry and in a Boiling Water Reactor (BWR) fuel assembly. Based on the two-fluid Eulerian solver, improvements of the STAR-CD code in the treatment of the drag, lift and wall lubrication forces in a dispersed two phase flow at high vapor (gas) phase fractions are investigated and introduced. These improvements constitute a new two phase modeling framework for STAR-CD, which has been shown to be superior as compared to the default models in STAR-CD. The conservation equations are discretized using the finite-volume method and solved using a solution procedure is based on Pressure Implicit with Splitting of Operators (PISO) algorithm, adapted to the solution of the two-fluid model. The improvements in the drag force modeling include investigation and integration of models with dependence on both void fraction and bubble diameter. The set of the models incorporated into STAR-CD is selected based on an extensive literature review focused on two phase systems with high vapor fractions. The research related to the modeling of wall lubrication force is focused on the validation of the already existing model in STAR-CD. The major contribution of this research is the development and implementation of an improved correlation for the lift coefficient used in the lift force formula. While a variety of correlations for the lift coefficient can be found in the open literature, most of those were derived from experiments conducted at low vapor (gas) phase fractions and are not applicable to the flow conditions existing in the BWRs. Therefore

  7. 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.

  8. Void-induced dissolution in molecular dynamics simulations of NaCl and water

    NASA Astrophysics Data System (ADS)

    Bahadur, Ranjit; Russell, Lynn M.; Alavi, Saman; Martin, Scot T.; Buseck, Peter R.

    2006-04-01

    To gain a better understanding of the interaction of water and NaCl at the surface during dissolution, we have used molecular dynamics to simulate the interface with two equal-sized slabs of solid NaCl and liquid water in contact. The introduction of voids in the bulk of the salt, as well as steps or pits on the surface of the NaCl slab results in a qualitative change of system structure, as defined by radial distribution functions (RDFs). As an example, the characteristic Na-Na RDF for the system changes from regularly spaced narrow peaks (corresponding to an ordered crystalline structure), to a broad primary and smaller secondary peak (corresponding to a disordered structure). The change is observed at computationally short time scales of 100ps, in contrast with a much longer time scale of 1μs expected for complete mixing in the absence of defects. The void fraction (which combines both bulk and surface defects) required to trigger dissolution varies between 15%-20% at 300K and 1atm, and has distinct characteristics for the physical breakdown of the crystal lattice. The void fraction required decreases with temperature. Sensitivity studies show a strong dependence of the critical void fraction on the quantity and distribution of voids on the surface, with systems containing a balanced number of surface defects and a rough surface showing a maximum tendency to dissolve. There is a moderate dependence on temperature, with a 5% decrease in required void fraction with a 100K increase in temperature, and a weak dependance on water potential model used, with the SPC, SPC/E, TIP4P, and RPOL models giving qualitatively identical results. The results were insensitive to the total quantity of water available for dissolution and the duration of the simulation.

  9. Modeling of void coalescence initiation and its impact on the prediction of material failure

    NASA Astrophysics Data System (ADS)

    Msolli, Sabeur; Bettaieb, Mohamed Ben; Abed-Meraim, Farid

    2016-10-01

    In the present paper, Thomason's criterion is coupled with the well-known Gurson-Tvergaard-Needleman (GTN) damage model and used for the determination of the critical void volume fraction fc, which marks the initiation of the coalescence stage. The onset of void coalescence predicted by Thomason's criterion is compared to that obtained by using a predefined fc, which is usually fitted on the basis of experimental results, as originally proposed in the GTN model. Comparisons are made in terms of both single finite element simulations and numerical results of deep drawing of a cup.

  10. Interfacial void segregation of Cl in Cu-Sn micro-connects

    NASA Astrophysics Data System (ADS)

    Ross, Glenn; Tao, Xiaoma; Broas, Mikael; Mäntyoja, Nikolai; Vuorinen, Vesa; Graff, Andreas; Altmann, Frank; Petzold, Matthias; Paulasto-Kröckel, Mervi

    2017-03-01

    A scanning transmission electron microscopy and an energy dispersive X-ray analysis of one non-annealed and one annealed sample (423 K for 4 hours) was performed. The results showed small and large voids appearing within the non-annealed and annealed samples respectively. In addition, chlorine segregated from the bulk into the voids. Ab initio calculations determined the formation energies for dilute solutions of chlorine and vacancies in Cu, Cu3Sn and Cu6Sn5. Results suggest that dilute solutions energetically favor vacancies, indicating a low chlorine solubility and a driving force for segregation. [Figure not available: see fulltext.

  11. Propagation of Love waves in a void medium over a sandy half space under gravity

    NASA Astrophysics Data System (ADS)

    Patra, Pulak; Gupta, Asit Kumar; Kundu, Santimoy

    2017-03-01

    The present study investigates the propagation of Love wave in a void layer resting over a sandy half space under the effect of gravitational force. The equations of motion have been gathered separately for different layers, and the boundary conditions have been introduced for two different layers at their interface. The mathematical analysis of the problem has been dealt with the help of Whittaker's function by expanding it asymptotically up to linear terms. The study reveals that in such a situation there exist two different wave fronts for the two above-mentioned layers: one is for the effects of gravity and sandy parameters, whereas other is for the effect of void parameter.

  12. A Void Fraction Characterisation by Low Frequency Acoustic Velocity Measurements in Microbubble Clouds

    NASA Astrophysics Data System (ADS)

    Cavaro, Matthieu

    Low frequency acoustic velocity measurements have been applied for the characterization of microbubble clouds generated in water. This method, based on the Wood's model (1941) links the acoustic velocity throughout a two-phase medium to its void fraction value. Low frequency means below resonance frequencies of the bubbles inside the cloud. An original bench was developed to allow the qualification of this method. The experiments conducted allowed us to characterize void fraction values between 10-3 and 10-7. The radii of the studied microbubbles are between a few micrometers and a hundred micrometers.

  13. Effect of void-size distribution on the Hugoniot state at low shock pressures.

    PubMed

    Griffiths, D J; Buettner, D J; Tsou, P

    1991-11-01

    In most theoretical and experimental investigations into the shock response of underdense solid media, the influence of the medium's mesostructure on the resulting pressure and degree of compaction has not been taken into account. In typical cases examined, shock pressures are well in excess of 1 GPa and this approach is clearly justified. However, at low pressures, calculations show that the distribution of void sizes can affect the final state achieved upon shocking the medium from a given initial porosity. This paper analyzes the response of porous aluminum to low pressure shocking and demonstrates a dependence of the final shocked state on the distribution of void sizes.

  14. Response Due to Concentrated Force in Micropolar Elastic Solid with Voids

    NASA Astrophysics Data System (ADS)

    Singh, R.; Singh, K.

    2014-11-01

    The eigen value approach, following Laplace and Fourier transforms has been employed to find the general solution of the field equation in a micropolar elastic solid with voids for the plane strain problem. An application of an infinite space with impulsive force has been taken to illustrate the utility of the approach. The integral transformations have been inverted by using a numerical inversion technique to get result in physical domain. The result in the form of normal displacement, volume fraction, normal force stress, tangential force stress and tangential couple stress components has been obtained numerically and illustrated graphically to depict the effect of micropolarity and voids.

  15. Void nucleation in biaxially strained ultrathin films of face-centered cubic metals

    NASA Astrophysics Data System (ADS)

    Kolluri, Kedarnath; Gungor, M. Rauf; Maroudas, Dimitrios

    2007-05-01

    We report an analysis of void nucleation as a relaxation mechanism in freestanding biaxially strained ultrathin films of face-centered cubic metals based on large-scale molecular-dynamics simulations. Above a critical strain level, multiple threading dislocations are emitted from the film surface. The surface step traces formed by gliding dislocations on intersecting and on adjacent parallel glide planes lead to formation and growth of surface pits and grooves, while vacancies form due to gliding of jogged dislocations and dislocation intersections. Coalescence of the surface pits with vacancy clusters is the precursor to the formation of a larger void extending across the film.

  16. Voiding in lead-free soldering of components with large solder pads

    NASA Astrophysics Data System (ADS)

    Dziurdzia, Barbara; Mikołajek, Janusz

    2016-12-01

    The paper presents the quantification of void formation in lead-free solder joints underneath bottom terminated components (BTCs) through X-ray inspection. Experiments were designed to investigate how void formation is affected by using vacuum in reflow soldering on the example of light emitted diode (LED) packages on metal core printed circuit boards (PCBs). Convection and vapour phase reflow soldering were used for LED assembly. X-ray inspection system analyzed the statistical distribution, mean value, standard deviation and process capability value Cpk of thermal pads coverage for various technological versions of LEDs.

  17. Apparatus for measuring the local void fraction in a flowing liquid containing a gas

    DOEpatents

    Dunn, P.F.

    1979-07-17

    The local void fraction in liquid containing a gas is measured by placing an impedance-variation probe in the liquid, applying a controlled voltage or current to the probe, and measuring the probe current or voltage. A circuit for applying the one electrical parameter and measuring the other includes a feedback amplifier that minimizes the effect of probe capacitance and a digitizer to provide a clean signal. Time integration of the signal provides a measure of the void fraction, and an oscilloscope display also shows bubble size and distribution.

  18. Application of magnetic resonance imaging to non-destructive void detection in watermelon

    NASA Astrophysics Data System (ADS)

    Saito, K.; Miki, T.; Hayashi, S.; Kajikawa, H.; Shimada, M.; Kawate, Y.; Nishizawa, T.; Ikegaya, D.; Kimura, N.; Takabatake, K.; Sugiura, N.; Suzuki, M.

    A novel application of magnetic resonance imaging (MRI) is described. The possibility of utilizing MRI for non-destructive quality evaluation of watermelons was studied. In this study, we applied MRI to the detection of internal voids in watermelons. In order to increase the measurement rate, we employed a one-dimensional projection profile method instead of observing a two-dimensional cross-sectional image. The void detection was carried out with this technique over 30 samples and 28 samples were correctly evaluated. The measurement rate was 900 ms per sample, which is an acceptable speed for a sorting machine in the agricultural field.

  19. Recurring priapism may be a symptom of voiding dysfunction – case report and literature review

    PubMed Central

    de Jesus, Lisieux Eyer; Teixeira, Leonardo; Bertelli, André

    2016-01-01

    ABSTRACT Recurring priapism is rare in pre-pubertal children and may be attributed to multiple causes. We propose that voiding dysfunction (VD) may also justify this symptom and detail a clinical case of recurring stuttering priapism associated to overactive bladder that completely resolved after usage of anticholinergics and urotherapy. Sacral parasympathetic activity is responsible for detrusor contraction and for spontaneous erections and a relationship between erections and bladder status has been proved in healthy subjects (morning erections) and models of medullar trauma. High bladder pressures and/or volumes, voiding incoordination and posterior urethritis can potentially trigger reflex erections. PMID:27256196

  20. Apparatus for measuring the local void fraction in a flowing liquid containing a gas

    DOEpatents

    Dunn, Patrick F.

    1981-01-01

    The local void fraction in liquid containing a gas is measured by placing an impedance-variation probe in the liquid, applying a controlled voltage or current to the probe, and measuring the probe current or voltage. A circuit for applying the one electrical parameter and measuring the other includes a feedback amplifier that minimizes the effect of probe capacitance and a digitizer to provide a clean signal. Time integration of the signal provides a measure of the void fraction, and an oscilloscope display also shows bubble size and distribution.

  1. Voids as alternatives to dark energy and the propagation of γ rays through the universe.

    PubMed

    DeLavallaz, Arnaud; Fairbairn, Malcolm

    2012-04-27

    We test the opacity of a void universe to TeV energy γ rays having obtained the extragalactic background light in that universe using a simple model and the observed constraints on the star formation rate history. We find that the void universe has significantly more opacity than a Λ cold dark matter universe, putting it at odds with observations of BL-Lac objects. We argue that while this method of distinguishing between the two cosmologies contains uncertainties, it circumvents any debates over fine-tuning.

  2. Effect of void-size distribution on the Hugoniot state at low shock pressures

    NASA Technical Reports Server (NTRS)

    Griffiths, David J.; Buettner, Douglas J.; Tsou, Peter

    1991-01-01

    In most theoretical and experimental investigations into the shock response of underdense solid media, the influence of the medium's mesostructure on the resulting pressure and degree of compaction has not been taken into account. In typical cases examined, shock pressures are well in excess of 1 GPa and this approach is clearly justified. However, at low pressures, calculations show that the distribution of void sizes can affect the final state achieved upon shocking the medium from a given initial porosity. This paper analyzes the response of porous aluminum to low pressure shocking and demonstrates a dependence of the final shocked state on the distribution of void sizes.

  3. Flow pattern, pressure drop and void fraction of two-phase gas-liquid flow in an inclined narrow annular channel

    SciTech Connect

    Wongwises, Somchai; Pipathattakul, Manop

    2006-03-01

    Two-phase flow pattern, pressure drop and void fraction in horizontal and inclined upward air-water two-phase flow in a mini-gap annular channel are experimentally studied. A concentric annular test section at the length of 880mm with an outer diameter of 12.5mm and inner diameter of 8mm is used in the experiments. The flow phenomena, which are plug flow, slug flow, annular flow, annular/slug flow, bubbly/plug flow, bubbly/slug-plug flow, churn flow, dispersed bubbly flow and slug/bubbly flow, are observed and recorded by high-speed camera. A slug flow pattern is found only in the horizontal channel while slug/bubbly flow patterns are observed only in inclined channels. When the inclination angle is increased, the onset of transition from the plug flow region to the slug flow region (for the horizontal channel) and from the plug flow region to slug/bubbly flow region (for inclined channels) shift to a lower value of superficial air velocity. Small shifts are found for the transition line between the dispersed bubbly flow and the bubbly/plug flow, the bubbly/plug flow and the bubbly/slug-plug flow, and the bubbly/plug flow and the plug flow. The rest of the transition lines shift to a higher value of superficial air velocity. Considering the effect of flow pattern on the pressure drop in the horizontal tube at low liquid velocity, the occurrence of slug flow stops the rise of pressure drop for a short while, before rising again after the air velocity has increased. However, the pressure does not rise abruptly in the tubes with {theta}=30{sup o} and 60{sup o} when the slug/bubbly flow occurs. At low gas and liquid velocity, the pressure drop increases, when the inclination angles changes from horizontal to 30{sup o} and 60{sup o}. Void fraction increases with increasing gas velocity and decreases with increasing liquid velocity. After increasing the inclination angle from horizontal to {theta}=30{sup o} and 60{sup o}, the void fraction appears to be similar, with a

  4. A dual-porous, biophysical void structure model of soil for the understanding of the conditions causing nitrous oxide emission

    NASA Astrophysics Data System (ADS)

    Matthews, G. Peter; Maurizio Laudone, G.; Whalle, W. Richard; Bird, Nigel; Gregory, Andrew; Cardenas, Laura; Misselbrook, Tom

    2010-05-01

    periodic boundary conditions, and with a critical percolation path with the correct percolation characteristics and void volume of the macro-porosity of the soil. • A solid phase between the pores of the large unit cell, with the correct volume of the fraction of larger soil aggregates (larger 1 mm). • All the remaining pores of the large unit cell, which are not part of the critical percolation path, filled with smaller unit cells, which account for the micro-porosity of the soil sample. We describe the construction of a model that closely matches the following characteristics of a specific example of typical arable soil, taken from the Warren field of the Rothamsted experimental farm at Woburn, although the model can be used for a wide range of soils: (i) macroporosity and microporosity as measured by the water retention curve, (ii) the shape of the water retention characteristic under a wide range of tensions, (iii) the soil texture, and (iv) the extent of irreducible water content. Process model We will describe the insertion of Michaelis-Menten kinetics and Crank-Nicholson diffusion equations into the precisely scaled model, building on previous diffusion modelling (Laudone, G. M. et al, Chem.Eng.Sci., 2008). Comparison with experiment A comparison with experimental results sheds light on (i) the positional relationships of aerobic and anaerobic bacteria relative to the critical percolation path, (ii) the relationship between the critical percolation path and the preferential / critical flow path (Figure 4), (iii) the extent of ignorance about the reaction kinetics of some of the fundamental processes occurring, (iv) the soil conditions that cause nitrous oxide emission, and (v) the effect of soil compaction on the emission. Acknowledgement This presentation is a summary of the some of the work of the BBSRC funded U.K. soil research consortium "Soil Programme for Quality and Resilience" (BB/E001793/1 and others), of which Matthews is principal investigator.

  5. 7 CFR 28.125 - No voiding or modifying claims for payment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Regulations Under the United States Cotton... 7 Agriculture 2 2010-01-01 2010-01-01 false No voiding or modifying claims for payment. 28.125 Section 28.125 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING...

  6. Laser fabrication of photorefractive Bragg reflectors, asymmetric waveguides and void arrays in glass

    NASA Astrophysics Data System (ADS)

    Itoh, Kazuyoshi; Watanabe, Wataru; Li, Yan; Yamada, Kazuhiro; Nishii, Junji

    2002-11-01

    We have been studying the refractive index changes and vacancies that are induced in silica glass by the irradiation of ultrashort laser pulses. By scanning the laser beam in the glass we can form 3-D shape of waveguides, arrays of tiny vacancies, called voids, and long holes with microscopic diameters. In this paper, we report on the asymmetry of the waveguide formed by linearly polarized ultrashort pulses. The formation of the photo-induced waveguide is normally accompanied by the filamentation, the self-trapping of laser beam due to nonlinear optical effects. The asymmetric cross-section of the waveguide structures explains properly the illusory birefringence of photo-induced waveguides observed earlier. The cross-sectional forms of the waveguides were observed by polishing and etching the cross-psections. We also report the possibility of forming asymmetric shapes of voids. The asymmetry of voids results from the beam profile. We controlled the profile by inserting apertures before the focusing lens. The asymmetry leads to the polarization dependence of diffraction from the array of voids. We also report on the formation of Bragg grating in glass. The Bragg gratings were formed in soda-lime glass. We succeeded in forming a series of three Bragg gratings. The formation of grating inside glass was confirmed by diffraction experiments and chemical etching of polished cross-sections.

  7. Generalized Rate Theory for Void and Bubble Swelling and its Application to Plutonium Metal Alloys

    SciTech Connect

    Allen, P. G.; Wolfer, W. G.

    2015-10-16

    In the classical rate theory for void swelling, vacancies and self-interstitials are produced by radiation in equal numbers, and in addition, thermal vacancies are also generated at the sinks, primarily at edge dislocations, at voids, and at grain boundaries. In contrast, due to the high formation energy of self-interstitials for normal metals and alloys, their thermal generation is negligible, as pointed out by Bullough and Perrin [1]. However, recent DFT calculations of the formation energy of self-interstitial atoms in bcc metals [2,3] have revealed that the sum of formation and migration energies for self-interstitials atoms (SIA) is of the same order of magnitude as for vacancies. This is illustrated in Fig. 1 that shows the ratio of the activation energies for thermal generation of SIA and vacancies. For fcc metals, this ratio is around three, but for bcc metals it is around 1.5. Reviewing theoretical predictions of point defect properties in δ-Pu [4], this ratio could possibly be less than one. As a result, thermal generation of SIA in bcc metals and in plutonium must be taken into considerations when modeling the growth of voids and of helium bubbles, and the classical rate theory (CRT) for void and bubble swelling must be extended to a generalized rate theory (GRT).

  8. Rock motion simulation and prediction of porosity distribution for a two-void-level retort

    SciTech Connect

    Preece, D.S.

    1990-01-01

    The computer program DMC (Distinct Motion Code) was developed in 1988 and 1989 to predict the motion of rock following a conventional blast. The ability to predict the rock motion associated with oil shale retort blasting, along with the induced porosity distribution, has been a driving force behind the development of DMC. Earlier this year DMC was used to simulate the rock motion associated with the rubblization of Occidental Oil Shale's Retort Number 8 which was a three-void-level retort processed in 1982. This paper discusses the algorithm developed to compute the porosity distribution of the muck after rock motion. It also contains a simulation of a two-void-level retort rubblization plan proposed by Ricketts, 1989. DMC is used to model the rock motion associated with the blasting and to obtain a final porosity distribution. Some improvement in the porosity distribution is seen over that observed in the three-void-level simulation. Thus, it may be that the two-void-level approach is not only more efficient to mine, but may also produce a more uniform rubble bed. 8 refs., 12 figs.

  9. Niobium-uranium alloys with voids of predetermined size and total volume

    NASA Technical Reports Server (NTRS)

    Mc Cluskey, J. K.; Wilhelm, H. A.

    1969-01-01

    Mixture of uranium oxide, niobium oxide, and graphite of various carbon-to-oxygen ratios is heated to a temperature below the melting point of the noibium-uranium alloy. The alloy is produced by this method with voids predetermined as to size and total volume.

  10. Could multiple voids explain the cosmic microwave background Cold Spot anomaly?

    NASA Astrophysics Data System (ADS)

    Naidoo, Krishna; Benoit-Lévy, Aurélien; Lahav, Ofer

    2016-06-01

    Understanding the observed Cold Spot (CS, temperature of ˜ - 150 μK at its centre) on the cosmic microwave background is an outstanding problem. Explanations vary from assuming it is just a ≳3σ primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ˜ - 50 μK. In this model the central CS temperature lies at ˜2σ but fails to explain the CS hot ring. An alternative multivoid model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multivoid scenarios) are removed. The CS tension with the Λ cold dark matter model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.

  11. Prolonged irritative voiding symptoms due to Enterobius vermicularis bladder infestation in an adult patient.

    PubMed

    Sammour, Zein Mohamed; Gomes, Cristiano Mendes; Tome, Andre Luiz Farinhas; Bruschini, Homero; Srougi, Miguel

    2008-08-01

    Enterobius vermicularis (pinworm) is one of the most prevalent intestinal parasites in the world. The urinary tract is rarely affected and few cases have been reported. We report a case of bladder infestation by mature female worms of E. vermicularis in a woman presenting with irritative voiding symptoms.

  12. The Effects of Drug and Behavior Therapy on Urgency and Voiding Frequency

    PubMed Central

    Burgio, Kathryn L.; Kraus, Stephen R.; Borello-France, Diane; Chai, Toby C.; Kenton, Kimberly; Goode, Patricia S.; Xu, Yan; Kusek, John W.

    2010-01-01

    Introduction and Hypotheses The objective of this study was to examine the effects of drug therapy alone and combined with behavioral therapy on urgency and 24-voiding frequency in women with urge-predominant incontinence and to identify predictors of change. Methods A planned analysis of data from a multi-site, randomized, controlled trial (N=307). Bladder diaries were used to document voids, incontinence, and urgency severity. Results Urgency scores decreased significantly within both treatment groups, but changes did not differ between groups (p=0.30). Improvement in urgency was associated with greater baseline urgency (p<0.0001) and black ethnicity (p=0.03). Voiding frequency increased with drug alone and decreased slightly with combined therapy (p=0.009), and improvement was associated with combined treatment (p<0.0001), higher baseline frequency (p<0.0001), and lower baseline incontinence episode frequency (p=0.001). Conclusions Although combined drug and behavioral therapy does not appear to improve urgency more than drug alone, it resulted in better outcomes on voiding frequency. PMID:20143047

  13. Pattern dependence of void formation on electromigration in Mg-containing Al-Si alloys

    NASA Astrophysics Data System (ADS)

    Akiya, Masahiro; Saitoh, Kazuhiro; Sakai, Kazuya

    2001-11-01

    The pattern dependence of alternating wide and narrow stripe structures was demonstrated in the investigation of electromigration mechanisms. Magnesium accumulated in the portion of the stripe near the cathode and gradually decreased toward the anode. A fatal large void appeared at the current change point near the cathode.

  14. Void formation in amorphous germanium due to high electronic energy deposition

    SciTech Connect

    Gaertner, K.; Joehrens, J.; Steinbach, T.; Schnohr, C. S.; Wesch, W.; Ridgway, M. C.

    2011-06-01

    The effect of high electronic energy deposition in amorphous germanium has been studied experimentally by Au irradiation with ion energies of up to 185 MeV and different angles of incidence and by molecular dynamics computer simulations. In both cases, the energy deposition leads to void formation accompanied by strong swelling of the amorphous germanium. The simulation results prove that the formation of the voids is mainly based on a shock wave mechanism and the swelling is determined by the competing processes of the formation and growth of voids on the one hand and the shrinking and annihilation of voids on the other hand. In full agreement between experiment and simulation, the amount of the swelling is a linear function of the total energy deposited into electronic processes and there exists a threshold value of the electronic energy loss per ion and depth for swelling. A comparison of the threshold values obtained by the experiment and the simulation suggests that approximately 20% of the energy deposited into electronic processes is converted into atomic motion.

  15. 'Void existence' as against 'annihilation existence': Differentiating two qualities in primitive mental states.

    PubMed

    Valdarsky, Irit Hameiri

    2015-10-01

    This paper attempts to distil out a particular quality of psychic (non)existence, which I call here 'void existence', from the quality predominantly explored in the psychoanalytic discourse on primitive mental states, which I call 'annihilation existence'. Achieving this phenomenological differentiation may make it easier to identify and work through extreme states in the analytic situation, when the patient is under the dominance of 'void existence'. I suggest that it is, as it were, a one-dimensional existence, in an infinite contour-less void, lacking any substantial internal object, lacking any substantial sense of psychic and/or somatic occurrences, and lacking any live representation of this very state of being. Hence, it lacks distress and anxiety, as well as calmness and peace. One might say that it is the inorganic within the organic; a quality of non-alive-ness within life. 'Annihilation existence' is existence in a two- or three-dimensional hollowed world, with flat and/or partial representations of self and object, which attracts acute distress and annihilation anxiety. It is a sort of existence on the brink of non-life, on the brink of the void; where a sense of catastrophic danger is brought on by the never-ending potentiality of the annihilation's realization. Both these psychic qualities can be encapsulated within neurotic and personality disorders, and the dominance of each can serve as defence against the dominance of the other. The theoretical discussion is supported by excerpts from an analysis.

  16. Maintaining Low Voiding Solder Die Attach for Power Die While Minimizing Die Tilt

    SciTech Connect

    Hamm, Randy; Peterson, Kenneth A.

    2015-10-01

    This paper addresses work to minimize voiding and die tilt in solder attachment of a large power die, measuring 9.0 mm X 6.5 mm X 0.1 mm (0.354” x 0.256” x 0.004”), to a heat spreader. As demands for larger high power die continue, minimizing voiding and die tilt is of interest for improved die functionality, yield, manufacturability, and reliability. High-power die generate considerable heat, which is important to dissipate effectively through control of voiding under high thermal load areas of the die while maintaining a consistent bondline (minimizing die tilt). Voiding was measured using acoustic imaging and die tilt was measured using two different optical measurement systems. 80Au-20Sn solder reflow was achieved using a batch vacuum solder system with optimized fixturing. Minimizing die tilt proved to be the more difficult of the two product requirements to meet. Process development variables included tooling, weight and solder preform thickness.

  17. Why a steady state void size distribution in irradiated UO2? A modeling approach

    NASA Astrophysics Data System (ADS)

    Maillard, S.; Martin, G.; Sabathier, C.

    2016-05-01

    In UO2 pellets irradiated in standard water reactor, Xe nano-bubbles nucleate, grow, coarsen and finally reach a quasi steady state size distribution: transmission electron microscope (TEM) observations typically report a concentration around 10-4 nm-3 and a radius around 0.5 nm. This phenomenon is often considered as a consequence of radiation enhanced diffusion, precipitation of gas atoms and ballistic mixing. However, in UO2 thin foils irradiated with energetic ions at room temperature, a nano-void population whose size distribution reaches a similar steady state can be observed, although quasi no foreign atoms are implanted nor significant cation vacancy diffusion expected in conditions. Atomistic simulations performed at low temperature only address the first stage of the process, supporting the assumption of void heterogeneous nucleation: 25 keV sub-cascades directly produce defect aggregates (loops and voids) even in the absence of gas atoms and thermal diffusion. In this work a semi-empirical stochastic model is proposed to enlarge the time scale covered by simulation up to damage levels where every point in the material undergoes the superposition of a large number of sub-cascade impacts. To account for the accumulation of these impacts, simple rules inferred from the atomistic simulation results are used. The model satisfactorily reproduces the TEM observations of nano-voids size and concentration, which paves the way for the introduction of a more realistic damage term in rate theory models.

  18. 40 CFR 1065.526 - Repeating of void modes or test intervals.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... that include hybrid energy storage features or emission controls that involve physical or chemical...) If one of the modes of a discrete-mode duty cycle is voided while running the duty cycle as provided... as specified in the standard-setting part. (d) If an individual mode of a discrete-mode duty...

  19. 40 CFR 86.614-84 - Hearings on suspension, revocation, and voiding of certificates of conformity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., and voiding of certificates of conformity. 86.614-84 Section 86.614-84 Protection of Environment... certificates of conformity. (a) Applicability. The procedures prescribed by this section apply whenever a... or revoke a certificate of conformity was made under § 86.612(d) prior to the decision to deny...

  20. Voiding urosonography: Contrast-enhanced ultrasound cystography to diagnose vesico-ureteric reflux: A pilot study.

    PubMed

    Babu, Ramesh; Gopinath, Vinu; Sai, Venkata

    2015-01-01

    We report two children with hydronephrosis, in whom we have utilized voiding urosonography (VUS) in the evaluation of vesico-ureteric reflux. With wider availability of ultrasound contrast agents and high-end ultrasound machines, VUS is likely to become a popular tool to diagnose or exclude VUR.