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Sample records for simplified voiding cystourethrography

  1. Comparison Between Photofluorography and Standard Fluoroscopic Voiding Cystourethrography in Evaluating Vesicoureteral Reflux in Children With Urinary Tract Infection

    PubMed Central

    Alamdaran, Seid Ali; Naseri, Mitra; Beheshtian, Ali

    2012-01-01

    Background Imaging of the urinary system is considered to be responsible for significant radiation in children. Objectives This study was conducted to measure and compare the radiation dose in spot films with photofluorography voiding cystourethrography (VCUG) in children. Patients and Methods 111 [222 Kidney Urinary Unit (KUU)] pediatric patients, aged 1 month to 5 years, with symptomatic urinary tract infection were enrolled in the study. Peak tube voltage (kVp), exposure setting (mAs), focus film distance (FFD), film size and DAP (after the exam) were recorded for all patients. To evaluate the validity of the photographs, we calculated sensitivity, specificity, predictive values and agreement between the two methods using the kappa statistic. If the kappa was greater than 0.75, between 0.4–0.75 or less than 0.4, then the agreement was excellent, good or poor, respectively. P values less than 0.05 were statistically significant. Results Vesicoureteral reflux (VUR) was detected in 74 KUU (33.3%) in standard films and in 71 (32%) in photographic images. The photographs had no false positives and 3 false negatives. Therefore, the new method had a sensitivity of 96%, a specificity of 100%, a negative predictive value of 98% and a positive predictive value of 100%. The two-method agreement in the VUR diagnosis for grades 1, 4, 5 and the overall grading were excellent (kappa > 0.83); however, for grades 2 and 3, agreement was 80%, which was good (kappa = 0.64). Conclusions Our study suggests that the high validity and excellent agreement of the photofluorography method in the diagnosis and grading of VUR, which is comparable to spot films and represents a 50%–90% reduction in radiation, makes it the preferred method. PMID:23573482

  2. Intrarenal Reflux: Diagnosis at Contrast-Enhanced Voiding Urosonography.

    PubMed

    Colleran, Gabrielle C; Barnewolt, Carol E; Chow, Jeanne S; Paltiel, Harriet J

    2016-08-01

    Vesicoureteral reflux (VUR) is a childhood condition that is usually diagnosed by fluoroscopic voiding cystourethrography (VCUG). Intrarenal reflux (IRR) of infected urine is believed to play an important role in the pathogenesis of reflux-associated pyelonephritis and subsequent parenchymal scarring and is traditionally depicted by fluoroscopic VCUG. This case series describes the phenomenon of IRR occurring in association with VUR in 4 children as depicted by contrast-enhanced voiding urosonography. The ability of contrast-enhanced voiding urosonography to show IRR when it occurs in conjunction with VUR compares favorably to that of fluoroscopic VCUG. PMID:27371375

  3. A simplified post preparation technique after Thermafil obturation: evaluation of apical microleakage and presence of voids using methylene blue dye penetration

    PubMed Central

    Pusinanti, Luca; Rubini, Riccardo; Pellati, Agnese; Zerman, Nicoletta

    2013-01-01

    Summary Aim To evaluate the apical microleakage of Thermafil obturations after three different post space preparation techniques. Materials and methods 33 root canals of mono-radiculated extracted teeth were prepared with M two and then obturated with Thermafil. Teeth so treated were then divided into three groups and the post space to middle root was prepared using three different techniques. In samples in group A the housing for the post was created using a Torpan bur, and the carrier was partially removed only in the coronal portion. In samples in group B the carrier was completely removed and gutta-percha was hand compacted, before canal preparation using a Torpan bur. In samples in group C the carrier was completely removed, without guttapercha compaction, before canal preparation using a Torpan bur. The roots were immersed for 72 hours in methylene blue dye solution and sectioned transversely at 1-3-5 mm from the apex for evaluation of dye penetration using a stereomicroscope. The data collected were processed using Win CAD software and subjected to statistical analysis using the Student t test for p<0.05. Results There were no significant differences between the three groups, except for the presence of voids in the intermediate section of teeth in groups B and C. Conclusions Post space preparation did not influence the apical seal, and gutta-percha without voids was always found in the last millimetre of the canal obturation. This study proposes a post preparation technique which provides for complete carrier removal using pliers, hand compaction of residual gutta-percha with a manual plugger and enlargement of the root canal, using appropriate post space burs, free of any interference from the carrier. Operating time is reduced, as is the risk of creating ledges or iatrogenic perforations. PMID:23991269

  4. Dysfunctional voiding.

    PubMed

    Chiozza, M L

    2002-01-01

    Wetting may be considered the Cinderella of paediatric medicine. Before discussing dysfunctional voiding, the milestones of the normal development of continence in the child and the definitions used to describe this topic are presented. Bladder storage requires (1): accommodation of increasing volumes of urine at low intravesical pressure and with appropriate sensation; (2): a bladder outlet that is closed and not modified during increase in intra-abdominal pressure; (3): absence of involuntary bladder contractions. Development of continence in the child involves three independent factors maturing concomitantly: (1) development of normal bladder capacity; (2) maturation of urethral sphincter function; (3) development of neural control over bladder-sphincter function. All these processes are discussed. Abnormalities of any of these maturational sequences, which run parallel and overlapping, may result in clinically evident abnormalities of bladder sphincter control. Although dysfunctional voiding (DV) in children is very common its prevalence has not been well studied and, to date, and its origin is not well known. In a correct evaluation of functional voiding we must take into account different elements: the bladder capacity (that increases during the first 8 years of life roughly 30 ml per year), the micturition frequency, post-void residual volumes, bladder dynamics, urinary flow rates. Thus the correct assessment of children with lower urinary tract dysfunction should include a detailed history. Signs of DV range from urge syndrome to complex incontinence patterns during the day and the night. In addition to incontinence problems, children may have frequency, urgency, straining to void, weak or interrupted urinary stream, urinary tract infections (UTIs) and chronic constipation with or without encopresis. DV are also referred in enuretic children who wet the bed more than one time per night and have a functional bladder capacity lower than attended for age

  5. Rearchitecting IT: Simplify. Simplify

    ERIC Educational Resources Information Center

    Panettieri, Joseph C.

    2006-01-01

    Simplifying and securing an IT infrastructure is not easy. It frequently requires rethinking years of hardware and software investments, and a gradual migration to modern systems. Even so, writes the author, universities can take six practical steps to success: (1) Audit software infrastructure; (2) Evaluate current applications; (3) Centralize…

  6. Monte Carlo estimation of radiation doses during paediatric barium meal and cystourethrography examinations

    NASA Astrophysics Data System (ADS)

    Dimitriadis, A.; Gialousis, G.; Makri, T.; Karlatira, M.; Karaiskos, P.; Georgiou, E.; Papaodysseas, S.; Yakoumakis, E.

    2011-01-01

    Organ doses are important quantities in assessing the radiation risk. In the case of children, estimation of this risk is of particular concern due to their significant radiosensitivity and the greater health detriment. The purpose of this study is to estimate the organ doses to paediatric patients undergoing barium meal and micturating cystourethrography examinations by clinical measurements and Monte Carlo simulation. In clinical measurements, dose-area products (DAPs) were assessed during examination of 50 patients undergoing barium meal and 90 patients undergoing cystourethrography examinations, separated equally within three age categories: namely newborn, 1 year and 5 years old. Monte Carlo simulation of photon transport in male and female mathematical phantoms was applied using the MCNP5 code in order to estimate the equivalent organ doses. Regarding the micturating cystourethrography examinations, the organs receiving considerable amounts of radiation doses were the urinary bladder (1.87, 2.43 and 4.7 mSv, the first, second and third value in the parentheses corresponds to neonatal, 1 year old and 5 year old patients, respectively), the large intestines (1.54, 1.8, 3.1 mSv), the small intestines (1.34, 1.56, 2.78 mSv), the stomach (1.46, 1.02, 2.01 mSv) and the gall bladder (1.46, 1.66, 2.18 mSv), depending upon the age of the child. Organs receiving considerable amounts of radiation during barium meal examinations were the stomach (9.81, 9.92, 11.5 mSv), the gall bladder (3.05, 5.74, 7.15 mSv), the rib bones (9.82, 10.1, 11.1 mSv) and the pancreas (5.8, 5.93, 6.65 mSv), depending upon the age of the child. DAPs to organ/effective doses conversion factors were derived for each age and examination in order to be compared with other studies.

  7. Gas in void galaxies

    NASA Astrophysics Data System (ADS)

    Kreckel, Kathryn Joyce

    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, and provide an observational test for theories of cosmological structure formation. We investigate the neutral hydrogen properties (i.e. content, morphology, kinematics) of void galaxies, both individually and systematically, using a combination of observations and simulations, to form a more complete understanding of the nature of these systems. We investigate in detail the H I morphology and kinematics of two void galaxies. One is an isolated polar disk galaxy in a diffuse cosmological wall situated between two 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. We also examine KK 246, the only confirmed galaxy located within the nearby Tully Void. It is a dwarf galaxy with an extremely extended H I disk and signs of an H I cloud with anomalous velocity. It also exhibits clear misalignment between the kinematical major and minor axes, and a general misalignment between the H I and optical major axes. The relative isolation and extreme underdense environment make these both very interesting cases for examining the role of gas accretion in galaxy evolution. To study void galaxies as a population, we have carefully selected a sample of 60 galaxies that reside in the deepest underdensities of geometrically identified voids within the SDSS. We have imaged this new Void Galaxy Survey in H I at the Westerbork Synthesis Radio Telescope with a typical resolution of 8 kpc, probing a volume of 1.2 Mpc and 12,000 km s^-1 surrounding each galaxy. We reach H I mass limits of 2 x 10^8 M_sun and column density sensitivities of 5 x 10^19 cm^-2

  8. 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.

  9. Voids of dark energy

    SciTech Connect

    Dutta, Sourish; Maor, Irit

    2007-03-15

    We investigate the clustering properties of a dynamical dark energy component. In a cosmic mix of a pressureless fluid and a light scalar field, we follow the linear evolution of spherical matter perturbations. We find that the scalar field tends to form underdensities in response to the gravitationally collapsing matter. We thoroughly investigate these voids for a variety of initial conditions, explain the physics behind their formation, and consider possible observational implications. Detection of dark energy voids will clearly rule out the cosmological constant as the main source of the present acceleration.

  10. Simplifying Blepharoplasty.

    PubMed

    Zoumalan, Christopher I; Roostaeian, Jason

    2016-01-01

    Blepharoplasty remains one of the most common aesthetic procedures performed today. Its popularity stems partly from the ability to consistently make significant improvements in facial aesthetics with a relatively short operation that carries an acceptable risk profile. In this article, the authors attempt to simplify the approach to both upper and lower lid blepharoplasty and provide an algorithm based on the individual findings for any given patient. The recent trend with both upper and lower lid blepharoplasty has been toward greater volume preservation and at times volume augmentation. A simplified approach to upper lid blepharoplasty focuses on removal of excess skin and judicious removal of periorbital fat. Avoidance of a hollow upper sulcus has been emphasized and the addition of volume with either fat grafting or fillers can be considered. Lower lid blepharoplasty can use a transcutaneous or a transconjunctival approach to address herniated fat pads while blending the lid-cheek junction through release of the orbitomalar ligament and volume augmentation with fat (by repositioning and/or grafting) or injectable fillers. Complications with upper lid blepharoplasty are typically minimal, particularly with conservative skin removal and volume preservation techniques. Lower lid blepharoplasty, conversely, can lead to more serious complications, including lid malposition, and therefore should be approached with great caution. Nevertheless, through an algorithmic approach that meets the needs of each individual patient, the approach to blepharoplasty may be simplified with consistent and predictable results. PMID:26710052

  11. Void/particulate detector

    DOEpatents

    Claytor, T.N.; Karplus, H.B.

    1983-09-26

    Apparatus for detecting voids and particulates in a flowing stream of fluid contained in a pipe may comprise: (a) a transducer for transmitting an ultrasonic signal into the stream, coupled to the pipe at a first location; (b) a second transducer for detecting the through-transmission of said signal, coupled to the pipe at a second location; (c) a third transducer for detecting the back-scattering of said signal, coupled to the pipe at a third location, said third location being upstream from said first location; (d) circuit means for normalizing the back-scattered signal from said third transducer to the through-transmitted signal from said second transducer; which normalized signal provides a measure of the voids and particulates flowing past said first location.

  12. 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.

  13. 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.

  14. 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.

  15. On the magnetic fields in voids

    NASA Astrophysics Data System (ADS)

    Beck, A. M.; Hanasz, M.; Lesch, H.; Remus, R.-S.; Stasyszyn, F. A.

    2013-02-01

    We study the possible magnetization of cosmic voids by void galaxies. Recently, observations revealed isolated star-forming galaxies within the voids. Furthermore, a major fraction of a voids volume is expected to be filled with magnetic fields of a minimum strength of about 10-15 G on Mpc scales. We estimate the transport of magnetic energy by cosmic rays (CR) from the void galaxies into the voids. We assume that CRs and winds are able to leave small isolated void galaxies shortly after they assembled, and then propagate within the voids. For a typical void, we estimate the magnetic field strength and volume-filling factor depending on its void galaxy population and possible contributions of strong active galactic nuclei (AGNs) which border the voids. We argue that the lower limit on the void magnetic field can be recovered, if a small fraction of the magnetic energy contained in the void galaxies or void bordering AGNs is distributed within the voids.

  16. Testing gravity using cosmic voids

    NASA Astrophysics Data System (ADS)

    Cai, Yan-Chuan; Padilla, Nelson; Li, Baojiu

    2015-07-01

    We explore voids in dark matter and halo fields from simulations of Λ cold dark matter and Hu-Sawicki f (R) models. In f (R) gravity, dark matter void abundances are greater than that of general relativity (GR). Differences for halo void abundances are much smaller, but still at the 2σ, 6σ and 14σ level for the f (R) model parameter |fR0| = 10-6, 10-5 and 10-4. Counter-intuitively, the abundance of large voids found using haloes in f (R) gravity is lower, which suggests that voids are not necessarily emptier of galaxies in this model. We find the halo number density profiles of voids are not distinguishable from GR, but the same voids are emptier of dark matter in f (R) gravity. This can be observed by weak gravitational lensing of voids, for which the combination of a spec-z and a photo-z survey over the same sky is necessary. For a volume of 1 (Gpc h-1)3, |fR0| = 10-5 and 10-4 may be distinguished from GR at 4σ and 8σ using the lensing tangential shear signal around voids. Sample variance and line-of-sight projection effect sets limits for constraining |fR0| = 10-6. This might be overcome with a larger volume. The smaller halo void abundance and the stronger lensing shear signal of voids in f (R) models may be combined to break the degeneracy between |fR0| and σ8. The outflow of dark matter from void centres are 5, 15 and 35 per cent faster in f (R) gravity for |fR0| = 10-6, 10-5 and 10-4. The velocity dispersions are greater than that in GR by similar amounts. Model differences in velocities imply potential powerful constraints for the model in phase space and in redshift space.

  17. 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.

  18. 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.

  19. Testing Gravity using Cosmic Voids

    NASA Astrophysics Data System (ADS)

    Falck, Bridget

    2016-01-01

    Though general relativity is well-tested on small (Solar System) scales, the late-time acceleration of the Universe provides strong motivation to test GR on cosmological scales. The difference between the small and large scale behavior of gravity is determined by the screening mechanism in modified gravity theories. Dark matter halos are often screened in these models, especially in models with Vainshtein screening, motivating a search for signatures of modified gravity in cosmic voids. We explore density, force, and velocity profiles of voids found in N-body simulations, using both dark matter particles and dark matter halos to identify the voids. The prospect of testing gravity using cosmic voids may be limited by the sparsity of halos as tracers of the density field.

  20. Percolation, wave propagation, and void link up effects in ductile fracture

    SciTech Connect

    Tonks, D.L.

    1994-02-01

    This work investigates the time evolution and spatial morphology of ductile damage based on void growth and coalecence. The size enhancement of damage cluster growth, as well as wave speed limiting of growth, are treated microscopically. Simplified 2D plane strain simulations using individual voids are done with uniaxial stress and explained with a probabilistic theory. At low strain rate, fracture occurs by long, localized cracks. At high strain rates, widespread, random damage breaks the system. The Voronoi tessellation of voids can be used to map out the spatial network of still solid material in 3D ductile fracture. Using it, the spallation porosity is calculated based on percolation theory.

  1. Clustering and bias measurements of SDSS voids

    NASA Astrophysics Data System (ADS)

    Clampitt, Joseph; Jain, Bhuvnesh; Sánchez, Carles

    2016-03-01

    Using a void catalogue from the Sloan Digital Sky Survey, we present the first measurements of void clustering and the corresponding void bias. Over the range 30-200 Mpc h-1, the void autocorrelation is detected at 5σ significance for voids of radius 15-20 Mpc h-1. We also measure the void-galaxy cross-correlation at higher signal to noise and compare the inferred void bias with the autocorrelation results. Void bias is constant with scale for voids of a given size, but its value falls from 5.6 ± 1.0 to below zero as the void radius increases from 15 to 30 Mpc h-1. The comparison of our measurements with carefully matched galaxy mock catalogues, with no free parameters related to the voids, shows that model predictions can be reliably made for void correlations. We study the dependence of void bias on tracer density and void size with a view to future applications. In combination with our previous lensing measurements of void mass profiles, these clustering measurements provide another step towards using voids as cosmological tracers.

  2. The life and death of cosmic voids

    NASA Astrophysics Data System (ADS)

    Sutter, P. M.; Elahi, Pascal; Falck, Bridget; Onions, Julian; Hamaus, Nico; Knebe, Alexander; Srisawat, Chaichalit; Schneider, Aurel

    2014-12-01

    We investigate the formation, growth, merger history, movement, and destruction of cosmic voids detected via the watershed transform code VIDE in a cosmological N-body dark matter Λ cold dark matter simulation. By adapting a method used to construct halo merger trees, we are able to trace individual voids back to their initial appearance and record the merging and evolution of their progenitors at high redshift. For the scales of void sizes captured in our simulation, we find that the void formation rate peaks at scale factor 0.3, which coincides with a growth in the void hierarchy and the emergence of dark energy. Voids of all sizes appear at all scale factors, though the median initial void size decreases with time. When voids become detectable they have nearly their present-day volumes. Almost all voids have relatively stable growth rates and suffer only infrequent minor mergers. Dissolution of a void via merging is very rare. Instead, most voids maintain their distinct identity as annexed subvoids of a larger parent. The smallest voids are collapsing at the present epoch, but void destruction ceases after scale factor 0.3. In addition, voids centres tend to move very little, less than 10-2 of their effective radii per ln a, over their lifetimes. Overall, most voids exhibit little radical dynamical evolution; their quiet lives make them pristine probes of cosmological initial conditions and the imprint of dark energy.

  3. Finding Brazing Voids by Holography

    NASA Technical Reports Server (NTRS)

    Galluccio, R.

    1986-01-01

    Vibration-induced interference fringes reveal locations of defects. Holographic apparatus used to view object while vibrated ultrasonically. Interference fringes in hologram reveal brazing defects. Holographic technique locates small voids in large brazed joints. Identifies unbrazed regions 1 in. to second power (6 cm to the second power) or less in area.

  4. 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.

  5. Testing the spherical evolution of cosmic voids

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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-1Mpc, 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.

  6. 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.

  7. 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.

  8. 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

  9. The nature of voids - I. Watershed void finders and their connection with theoretical models

    NASA Astrophysics Data System (ADS)

    Nadathur, S.; Hotchkiss, S.

    2015-12-01

    The statistical study of voids in the matter distribution promises to be an important tool for precision cosmology, but there are known discrepancies between theoretical models of voids and the voids actually found in large simulations or galaxy surveys. The empirical properties of observed voids are also not well understood. In this paper, we study voids in an N-body simulation, using the ZOBOV watershed algorithm. As in other studies, we use sets of subsampled dark matter particles as tracers to identify voids, but we use the full-resolution simulation output to measure dark matter densities at the identified locations. Voids span a wide range of sizes and densities, but there is a clear trend towards larger voids containing deeper density minima, a trend which is expected for all watershed void finders. We also find that the tracer density at void locations is usually smaller than the true density, and that this relationship depends on the sampling density of tracers. We show that fits given in the literature fail to match the observed density profiles of voids. The average enclosed density contrast within watershed voids varies widely with both the size of the void and the minimum density within it, but is always far from the shell-crossing threshold expected from theoretical models. Voids with deeper density minima also show much broader density profiles. We discuss the implications of these results for the excursion set approach to modelling such voids.

  10. 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

  11. Nocturia: The circadian voiding disorder.

    PubMed

    Kim, Jin Wook; Moon, Young Tae; Kim, Kyung Do

    2016-05-01

    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

  12. Conservative management of voiding dysfunction

    PubMed Central

    Patel, Anita

    2007-01-01

    This review article discusses the efficacy of various conservative therapies in the management of voiding dysfunction with special reference to urinary incontinence. The article emphasizes the fact that conservative therapies have limited side effects and they do not jeopardize future treatment options. Behaviour therapy, pelvic floor therapy and biofeedback; electrical and magnetic stimulation are discussed here individually. Though there is unanimous agreement that these therapies improve quality of life, complete cure is rare. All therapies work better in conjunction with each other rather than in isolation. The review also highlights the need for randomized controlled trials of better methodology. PMID:19675794

  13. Stealth Supersymmetry simplified

    NASA Astrophysics Data System (ADS)

    Fan, JiJi; Krall, Rebecca; Pinner, David; Reece, Matthew; Ruderman, Joshua T.

    2016-07-01

    In Stealth Supersymmetry, bounds on superpartners from direct searches can be notably weaker than in standard supersymmetric scenarios, due to suppressed missing energy. We present a set of simplified models of Stealth Supersymmetry that motivate 13 TeV LHC searches. We focus on simplified models within the Natural Supersymmetry framework, in which the gluino, stop, and Higgsino are assumed to be lighter than other superpartners. Our simplified models exhibit novel decay patterns that differ significantly from topologies of the Minimal Supersymmetric Standard Model, with and without R-parity. We determine limits on stops and gluinos from searches at the 8 TeV LHC. Existing searches constitute a powerful probe of Stealth Supersymmetry gluinos with certain topologies. However, we identify simplified models where the gluino can be considerably lighter than 1 TeV. Stops are significantly less constrained in Stealth Supersymmetry than the MSSM, and we have identified novel stop decay topologies that are completely unconstrained by existing LHC searches.

  14. 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. PMID:24580436

  15. Universal density profile for cosmic voids.

    PubMed

    Hamaus, Nico; Sutter, P M; Wandelt, Benjamin D

    2014-06-27

    We present a simple empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function is universal across void size and redshift, accurately describing a large radial range of scales around void centers with only two free parameters. In analogy to halo density profiles, these parameters describe the scale radius and the central density of voids. While we initially start with a more general four-parameter model, we find two of its parameters to be redundant, as they follow linear trends with the scale radius in two distinct regimes of the void sample, separated by its compensation scale. Assuming linear theory, we derive an analytic formula for the velocity profile of voids and find an excellent agreement with the numerical data as well. In our companion paper [Sutter et al., arXiv:1309.5087 [Mon. Not. R. Astron. Soc. (to be published)

  16. 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.

  17. Void evolution in polycarbonate at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Chen, Y. H.; Feng Chou, Kuo; Li, C. L.; Lee, Sanboh

    2011-08-01

    The void evolution in polycarbonate (PC) at elevated temperatures was investigated. Internal cylindrical cracks and voids were induced in PC by Nd-YAG laser irradiation. During the annealing at temperatures of 177-197 °C, the spherical void grows to a maximum size, which then decreases, and is finally leveling off. A model of void evolution based on the evaporation and condensation mechanisms for growth and shrinkage is proposed. The theoretical predictions are in good agreement with the experimental data. The activation energies of evaporation and condensation processes are determined to be 477.31 and 611.49 kJ/mol, respectively.

  18. Void evolution in polycarbonate at elevated temperatures

    SciTech Connect

    Chen, Y. H.; Li, C. L.; Lee, Sanboh; Kuo Feng Chou

    2011-08-15

    The void evolution in polycarbonate (PC) at elevated temperatures was investigated. Internal cylindrical cracks and voids were induced in PC by Nd-YAG laser irradiation. During the annealing at temperatures of 177-197 deg. C, the spherical void grows to a maximum size, which then decreases, and is finally leveling off. A model of void evolution based on the evaporation and condensation mechanisms for growth and shrinkage is proposed. The theoretical predictions are in good agreement with the experimental data. The activation energies of evaporation and condensation processes are determined to be 477.31 and 611.49 kJ/mol, respectively.

  19. 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.

  20. Void Fraction Instrument operation and maintenance manual

    SciTech Connect

    Borgonovi, G.; Stokes, T.I.; Pearce, K.L.; Martin, J.D.; Gimera, M.; Graves, D.B.

    1994-09-01

    This Operations and Maintenance Manual (O&MM) addresses riser installation, equipment and personnel hazards, operating instructions, calibration, maintenance, removal, and other pertinent information necessary to safely operate and store the Void Fraction Instrument. Final decontamination and decommissioning of the Void Fraction Instrument are not covered in this document.

  1. Pores and Void in Asclepiades' Physical Theory.

    PubMed

    Leith, David

    2012-01-01

    This paper examines a fundamental, though relatively understudied, aspect of the physical theory of the physician Asclepiades of Bithynia, namely his doctrine of pores. My principal thesis is that this doctrine is dependent on a conception of void taken directly from Epicurean physics. The paper falls into two parts: the first half addresses the evidence for the presence of void in Asclepiades' theory, and concludes that his conception of void was basically that of Epicurus; the second half focuses on the precise nature of Asclepiadean pores, and seeks to show that they represent void interstices between the primary particles of matter which are the constituents of the human body, and are thus exactly analogous to the void interstices between atoms within solid objects in Epicurus' theory. PMID:22984299

  2. Pores and Void in Asclepiades’ Physical Theory

    PubMed Central

    Leith, David

    2012-01-01

    This paper examines a fundamental, though relatively understudied, aspect of the physical theory of the physician Asclepiades of Bithynia, namely his doctrine of pores. My principal thesis is that this doctrine is dependent on a conception of void taken directly from Epicurean physics. The paper falls into two parts: the first half addresses the evidence for the presence of void in Asclepiades’ theory, and concludes that his conception of void was basically that of Epicurus; the second half focuses on the precise nature of Asclepiadean pores, and seeks to show that they represent void interstices between the primary particles of matter which are the constituents of the human body, and are thus exactly analogous to the void interstices between atoms within solid objects in Epicurus’ theory. PMID:22984299

  3. Testing spherical evolution for modelling void abundances

    NASA Astrophysics Data System (ADS)

    Achitouv, Ixandra; Neyrinck, Mark; Paranjape, Aseem

    2015-08-01

    We compare analytical predictions of void volume functions to those measured from N-body simulations, detecting voids with the ZOBOV void finder. We push to very small, non-linear voids, below few Mpc radius, by considering the unsampled dark matter density field. We also study the case where voids are identified using haloes. We develop analytical formula for the void abundance of both the excursion set approach and the peaks formalism. These formulas are valid for random walks smoothed with a top-hat filter in real space, with a large class of realistic barrier models. We test the extent to which the spherical evolution approximation, which forms the basis of the analytical predictions, models the highly aspherical voids that occur in the cosmic web, and are found by a watershed-based algorithm such as ZOBOV. We show that the volume function returned by ZOBOV is quite sensitive to the choice of treatment of subvoids, a fact that has not been appreciated previously. For reasonable choices of subvoid exclusion, we find that the Lagrangian density δv of the ZOBOV voids - which is predicted to be a constant δv ≈ -2.7 in the spherical evolution model - is different from the predicted value, showing substantial scatter and scale dependence. This result applies to voids identified at z = 0 with effective radius between 1 and 10 h-1 Mpc. Our analytical approximations are flexible enough to give a good description of the resulting volume function; however, this happens for choices of parameter values that are different from those suggested by the spherical evolution assumption. We conclude that analytical models for voids must move away from the spherical approximation in order to be applied successfully to observations, and we discuss some possible ways forward.

  4. Can Computers Simplify Admissions?

    ERIC Educational Resources Information Center

    Bruker, Robert M.

    1978-01-01

    Based on experience with a simplified admissions concept, Southern Illinois University is satisfied that the admissions process has been made easier for prospective students, high school counselors, and admissions staff. The computer does not make decisions regarding admission of a student, but reduced work loads for everyone concerned. (Author)

  5. 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.

  6. VIDE: The Void IDentification and Examination toolkit

    NASA Astrophysics Data System (ADS)

    Sutter, P. M.; Lavaux, G.; Hamaus, N.; Pisani, A.; Wandelt, B. D.; Warren, M.; Villaescusa-Navarro, F.; Zivick, P.; Mao, Q.; Thompson, B. B.

    2015-03-01

    We present VIDE, the Void IDentification and Examination toolkit, an open-source Python/C++ code for finding cosmic voids in galaxy redshift surveys and N -body simulations, characterizing their properties, and providing a platform for more detailed analysis. At its core, VIDE uses a substantially enhanced version of ZOBOV (Neyinck 2008) to calculate a Voronoi tessellation for estimating the density field and performing a watershed transform to construct voids. Additionally, VIDE provides significant functionality for both pre- and post-processing: for example, VIDE can work with volume- or magnitude-limited galaxy samples with arbitrary survey geometries, or dark matter particles or halo catalogs in a variety of common formats. It can also randomly subsample inputs and includes a Halo Occupation Distribution model for constructing mock galaxy populations. VIDE uses the watershed levels to place voids in a hierarchical tree, outputs a summary of void properties in plain ASCII, and provides a Python API to perform many analysis tasks, such as loading and manipulating void catalogs and particle members, filtering, plotting, computing clustering statistics, stacking, comparing catalogs, and fitting density profiles. While centered around ZOBOV, the toolkit is designed to be as modular as possible and accommodate other void finders. VIDE has been in development for several years and has already been used to produce a wealth of results, which we summarize in this work to highlight the capabilities of the toolkit. VIDE is publicly available at

  7. Antilensing: the bright side of voids.

    PubMed

    Bolejko, Krzysztof; Clarkson, Chris; Maartens, Roy; Bacon, David; Meures, Nikolai; Beynon, Emma

    2013-01-11

    More than half of the volume of our Universe is occupied by cosmic voids. The lensing magnification effect from those underdense regions is generally thought to give a small dimming contribution: objects on the far side of a void are supposed to be observed as slightly smaller than if the void were not there, which together with conservation of surface brightness implies net reduction in photons received. This is predicted by the usual weak lensing integral of the density contrast along the line of sight. We show that this standard effect is swamped at low redshifts by a relativistic Doppler term that is typically neglected. Contrary to the usual expectation, objects on the far side of a void are brighter than they would be otherwise. Thus the local dynamics of matter in and near the void is crucial and is only captured by the full relativistic lensing convergence. There are also significant nonlinear corrections to the relativistic linear theory, which we show actually underpredicts the effect. We use exact solutions to estimate that these can be more than 20% for deep voids. This remains an important source of systematic errors for weak lensing density reconstruction in galaxy surveys and for supernovae observations, and may be the cause of the reported extra scatter of field supernovae located on the edge of voids compared to those in clusters. PMID:23383886

  8. Simplified Parallel Domain Traversal

    SciTech Connect

    Erickson III, David J

    2011-01-01

    Many data-intensive scientific analysis techniques require global domain traversal, which over the years has been a bottleneck for efficient parallelization across distributed-memory architectures. Inspired by MapReduce and other simplified parallel programming approaches, we have designed DStep, a flexible system that greatly simplifies efficient parallelization of domain traversal techniques at scale. In order to deliver both simplicity to users as well as scalability on HPC platforms, we introduce a novel two-tiered communication architecture for managing and exploiting asynchronous communication loads. We also integrate our design with advanced parallel I/O techniques that operate directly on native simulation output. We demonstrate DStep by performing teleconnection analysis across ensemble runs of terascale atmospheric CO{sub 2} and climate data, and we show scalability results on up to 65,536 IBM BlueGene/P cores.

  9. 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.

  10. Infrared Thermal Sensing Of Sewer Voids

    NASA Astrophysics Data System (ADS)

    Weil, Gary J.

    1984-03-01

    The deterioration of sewer systems and their associated infrastructure is one of the most serious problems facing city, state, federal, and world authorities. As an example, three large sewer voids in the St. Louis Metropolitan area caused over $2,000,000 in repair costs in only one year. The detection of voids in and around underground sewer lines, as well as the detection of effluent leakages is necessary when determining the priority of structures for repair. At the present time sewer voids are sometimes detected by manual methods which are expensive, time consuming, and not extremely accurate. Most of the time, the void is not detected until the street caves in. Infrared thermography has been found to be capable of detecting voids around underground sewer systems because under certain conditions, temperature differentials exist between various types of materials, effluents, and cavities. This paper describes the problem of deteriorating sewer systems, the field tests used to detect sewer voids, the equipment used in the field tests, the theories used to design the tests, various complicating factors, and anticipated future refinements on the procedure.

  11. Void formation and roughening in slow fracture.

    PubMed

    Afek, Itai; Bouchbinder, Eran; Katzav, Eytan; Mathiesen, Joachim; Procaccia, Itamar

    2005-06-01

    Slow crack propagation in ductile, and in certain brittle materials, appears to take place via the nucleation of voids ahead of the crack tip due to plastic yields, followed by the coalescence of these voids. Postmortem analysis of the resulting fracture surfaces of ductile and brittle materials on the microm-mm and the nm scales, respectively, reveals self-affine cracks with anomalous scaling exponent zeta approximately = 0.8 in 3 dimensions and zeta approximately = 0.65 in 2 dimensions. In this paper we present an analytic theory based on the method of iterated conformal maps aimed at modelling the void formation and the fracture growth, culminating in estimates of the roughening exponents in 2 dimensions. In the simplest realization of the model we allow one void ahead of the crack, and address the robustness of the roughening exponent. Next we develop the theory further, to include two voids ahead of the crack. This development necessitates generalizing the method of iterated conformal maps to include doubly connected regions (maps from the annulus rather than the unit circle). While mathematically and numerically feasible, we find that the employment of the stress field as computed from elasticity theory becomes questionable when more than one void is explicitly inserted into the material. Thus further progress in this line of research calls for improved treatment of the plastic dynamics. PMID:16089840

  12. Counting voids to probe dark energy

    NASA Astrophysics Data System (ADS)

    Pisani, Alice; Sutter, P. M.; Hamaus, Nico; Alizadeh, Esfandiar; Biswas, Rahul; Wandelt, Benjamin D.; Hirata, Christopher M.

    2015-10-01

    We show that the number of observed voids in galaxy redshift surveys is a sensitive function of the equation of state of dark energy. Using the Fisher matrix formalism, we find the error ellipses in the w0-wa plane when the equation of state of dark energy is assumed to be of the form wCPL(z )=w0+waz /(1 +z ) . We forecast the number of voids to be observed with the ESA Euclid satellite and the NASA WFIRST mission, taking into account updated details of the surveys to reach accurate estimates of their power. The theoretical model for the forecast of the number of voids is based on matches between abundances in simulations and the analytical prediction. To take into account the uncertainties within the model, we marginalize over its free parameters when calculating the Fisher matrices. The addition of the void abundance constraints to the data from Planck, HST and supernova survey data noticeably tighten the w0-wa parameter space. We, thus, quantify the improvement in the constraints due to the use of voids and demonstrate that the void abundance is a sensitive new probe for the dark energy equation of state.

  13. Cluster-Void Degeneracy Breaking: Dark Energy, Planck, and the Largest Cluster and Void

    NASA Astrophysics Data System (ADS)

    Sahlén, Martin; Zubeldía, Íñigo; Silk, Joseph

    2016-03-01

    Combining galaxy cluster and void abundances breaks the degeneracy between mean matter density {{{Ω }}}{{m}} and power-spectrum normalization {σ }8. For the first time for voids, we constrain {{{Ω }}}{{m}}=0.21+/- 0.10 and {σ }8=0.95+/- 0.21 for a flat Λ CDM universe, using extreme-value statistics on the claimed largest cluster and void. The Planck-consistent results detect dark energy with two objects, independently of other dark energy probes. Cluster-void studies are also complementary in scale, density, and nonlinearity, and are of particular interest for testing modified-gravity models.

  14. 75 FR 81459 - Simplified Proceedings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-28

    ... Simplified Proceedings in certain civil penalty proceedings. 75 FR 28223. The Commission explained that since... simplify the procedures for handling certain civil penalty proceedings. DATES: The final rule takes effect... to deal with that burgeoning caseload, the Commission is considering methods to simplify...

  15. 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....

  16. 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....

  17. 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....

  18. 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....

  19. 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....

  20. Reliability Impact of Stockpile Aging: Stress Voiding

    SciTech Connect

    ROBINSON,DAVID G.

    1999-10-01

    The objective of this research is to statistically characterize the aging of integrated circuit interconnects. This report supersedes the stress void aging characterization presented in SAND99-0975, ''Reliability Degradation Due to Stockpile Aging,'' by the same author. The physics of the stress voiding, before and after wafer processing have been recently characterized by F. G. Yost in SAND99-0601, ''Stress Voiding during Wafer Processing''. The current effort extends this research to account for uncertainties in grain size, storage temperature, void spacing and initial residual stress and their impact on interconnect failure after wafer processing. The sensitivity of the life estimates to these uncertainties is also investigated. Various methods for characterizing the probability of failure of a conductor line were investigated including: Latin hypercube sampling (LHS), quasi-Monte Carlo sampling (qMC), as well as various analytical methods such as the advanced mean value (Ah/IV) method. The comparison was aided by the use of the Cassandra uncertainty analysis library. It was found that the only viable uncertainty analysis methods were those based on either LHS or quasi-Monte Carlo sampling. Analytical methods such as AMV could not be applied due to the nature of the stress voiding problem. The qMC method was chosen since it provided smaller estimation error for a given number of samples. The preliminary results indicate that the reliability of integrated circuits due to stress voiding is very sensitive to the underlying uncertainties associated with grain size and void spacing. In particular, accurate characterization of IC reliability depends heavily on not only the frost and second moments of the uncertainty distribution, but more specifically the unique form of the underlying distribution.

  1. Simplified Vicarious Radiometric Calibration

    NASA Technical Reports Server (NTRS)

    Stanley, Thomas; Ryan, Robert; Holekamp, Kara; Pagnutti, Mary

    2010-01-01

    A measurement-based radiance estimation approach for vicarious radiometric calibration of spaceborne multispectral remote sensing systems has been developed. This simplified process eliminates the use of radiative transfer codes and reduces the number of atmospheric assumptions required to perform sensor calibrations. Like prior approaches, the simplified method involves the collection of ground truth data coincident with the overpass of the remote sensing system being calibrated, but this approach differs from the prior techniques in both the nature of the data collected and the manner in which the data are processed. In traditional vicarious radiometric calibration, ground truth data are gathered using ground-viewing spectroradiometers and one or more sun photometer( s), among other instruments, located at a ground target area. The measured data from the ground-based instruments are used in radiative transfer models to estimate the top-of-atmosphere (TOA) target radiances at the time of satellite overpass. These TOA radiances are compared with the satellite sensor readings to radiometrically calibrate the sensor. Traditional vicarious radiometric calibration methods require that an atmospheric model be defined such that the ground-based observations of solar transmission and diffuse-to-global ratios are in close agreement with the radiative transfer code estimation of these parameters. This process is labor-intensive and complex, and can be prone to errors. The errors can be compounded because of approximations in the model and inaccurate assumptions about the radiative coupling between the atmosphere and the terrain. The errors can increase the uncertainty of the TOA radiance estimates used to perform the radiometric calibration. In comparison, the simplified approach does not use atmospheric radiative transfer models and involves fewer assumptions concerning the radiative transfer properties of the atmosphere. This new technique uses two neighboring uniform

  2. 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.

  3. 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.

  4. Lattice dependent motion of voids during electromigration

    SciTech Connect

    Sindermann, S. P.; Latz, A.; Dumpich, G.; Wolf, D. E.; Meyer zu Heringdorf, F.-J.

    2013-04-07

    The influence of the crystal lattice configuration to electromigration processes, e.g., void formation and propagation, is investigated in suitable test structures. They are fabricated out of self-assembled, bi-crystalline Ag islands, grown epitaxially on a clean Si(111) surface. The {mu}m-wide and approximately 100 nm thick Ag islands are a composition of a Ag(001) and a Ag(111) part. By focused ion beam milling, they are structured into wires with a single grain boundary, the orientation of which can be chosen arbitrarily. In-situ scanning electron microscopy (SEM) allows to capture an image sequence during electrical stressing and monitors the development of voids and hillocks in time. To visualize the position and motion of voids, we calculate void maps using a threshold algorithm. Most of the information from the SEM image sequence is compressed into one single image. Our present electromigration studies are based on in-situ SEM investigations for three different lattice configurations: Ag(001) (with electron current flow in [110] direction), Ag(111) (with electron current flow in [112] direction), and additionally 90 Ring-Operator rotated Ag(111) (with electron current flow in [110] direction). Our experimental results show that not only the formation and shape but also the motion direction of voids strongly depends on the crystal orientation.

  5. 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.

  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. 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.

  8. 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.

  9. Investigations on void morphology in CFRP composite materials and ultrasonic scattering attenuation based on a 2D random void model

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, S. S.; Chen, J.; Liang, X. Y.; Li, X. M.

    2012-05-01

    A 2D random void model (RVM) is proposed to describe voids morphology in Carbon Fiber Reinforced Plastic (CFRP) composite materials and used to investigate Ultrasonic Scattering Attenuation Coefficient (USAC). Void morphology simulations from RVM present good matches to micrographic observations. The fluctuations of USAC due to the randomness of void morphology and their dependence on the frequency have been discussed, which are significantly helpful to clarify ultrasonic scattering attenuation mechanism from voids in nature.

  10. Discovery of Lyalpha Clouds in Cosmic Voids

    NASA Astrophysics Data System (ADS)

    Stocke, John T.; Shull, J. M.; Penton, S. V.; Donahue, M.; Carilli, C.

    1995-05-01

    The HST/GHRS + G160M grating was used to obtain high resolution spectra of four very bright AGN located behind voids in the nearby distribution of bright galaxies (i.e. CfA and Arecibo redshift survey regions). A total of 9 Lyalpha absorption lines were discovered ranging in equivalent widths from 28 to 240 m Angstroms at velocities of cz=1500-10000 km/s. Of these 9, we identify 7 with supercluster structures and two in voids: one in the sightline of Mrk 501 at cz=7740 km/s and one in the sightline of Mrk 421 at cz=3020 km/s. Optical spectroscopy at Palomar and redshifted HI imaging at Westerbork fail to find faint galaxies or HI clouds close to the void absorption system in the Mrk 501 case. Thus, the voids are not entirely devoid of matter and not all Lyalpha clouds are associated with galaxies. Also, since the pathlengths through voids and superclusters probed by our observations thus far are nearly equal, there is some evidence that statistically the Lyalpha clouds avoid the voids. The nearest galaxy neighbors to these absorbing clouds are 0.45--5.9 Mpc away and thus too far away to be physically associated by most models, although some of the smaller nearest neighbor distances suggest a tidal debris origin to these clouds. Our results on local Lyalpha clouds are in full agreement with those found by Weymann, Morris et al. for the 3C273 sightline but disagree with results for the higher equivalent width systems where much closer cloud-galaxy associations were found by Lanzetta et al.

  11. Ductile damage model with void coalescence

    SciTech Connect

    Tonks, D.L.

    1995-03-01

    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. Underlying physics of the model is the nucleation, growth, and coalescence of voids in a plastically flowing solid. Implementation of the model in hydrocodes is discussed.

  12. 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.

  13. Effect of radiation-induced segregation on void nucleation

    SciTech Connect

    Si-Ahmed, A.; Wolfer, W.G.

    1982-01-01

    The effect of segregation on void nucleation is investigated utilizing previous results for the capture efficiency of coated void. First, it is shown that any segregation, whether or not it leads to actual precipitation, leads to a modification of the bias factors for any sink. Small increases of either the lattice parameters or the elastic moduli result in reduced interstitial bias factors. Second, segregations to void embryos not only changes their capture efficiencies but also the surface energy. The effect of these changes on the void nucleation rate is studied in quantitative terms. When the segregation to voids results in an increase of the local lattice parameters by 0.4% or an increase of the shear modulus by 3%, the ultimate void nucleation rate is reached. Further increases no longer enhance void nucleation. Void nucleation without segregation effects would only be possible if the dislocation bias exceeds 50%. With segregation, void nucleation is not strongly dependent on the dislocation bias.

  14. 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.

  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. The nature of voids - II. Tracing underdensities with biased galaxies

    NASA Astrophysics Data System (ADS)

    Nadathur, S.; Hotchkiss, S.

    2015-11-01

    We study how the properties of cosmic voids depend on those of the tracer galaxy populations in which they are identified. We use a suite of halo occupation distribution mocks in a simulation, identify voids in these populations using the ZOBOV void finder and measure their abundances, sizes, tracer densities and dark matter content. To separate the effects of bias from those of sampling density, we do the same for voids traced by randomly downsampled subsets of the simulation dark matter particles. At the same sampling density, galaxy bias reduces the total number of voids by ˜50 per cent and can dramatically change their size distribution. The matter content of voids in biased and unbiased tracers also differs. Deducing void properties from simulation therefore requires the use of realistic galaxy mocks. We discuss how the void observables can be related to their matter content. In particular we consider the compensation of the total mass deficit in voids and find that the distinction between over- and undercompensated voids is not a function of void size alone, as has previously been suggested. However, we find a simple linear relationship between the average density of tracers in the void and the total mass compensation on much larger scales. The existence of this linear relationship holds independent of the bias and sampling density of the tracers. This provides a universal tool to classify void environments and will be important for the use of voids in observational cosmology.

  17. "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.

  18. Making Ceramic Reference Specimens Containing Seeded Voids

    NASA Technical Reports Server (NTRS)

    Baaklini, George Y.; Klima, Stanley J.; Roth, Don J.

    1994-01-01

    Internal and surface voids of known sizes incorporated into silicon carbide and silicon nitride ceramic reference specimens at prescribed locations. Specimens used to demonstrate sensitivity and resolution in nondestructive examination techniques like scanning laser acoustic microscopy and x-radiography, and to assist in establishing proper examination procedures.

  19. Healing Voids In Interconnections In Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Cuddihy, Edward F.; Lawton, Russell A.; Gavin, Thomas

    1989-01-01

    Unusual heat treatment heals voids in aluminum interconnections on integrated circuits (IC's). Treatment consists of heating IC to temperature between 200 degrees C and 400 degrees C, holding it at that temperature, and then plunging IC immediately into liquid nitrogen. Typical holding time at evaluated temperature is 30 minutes.

  20. 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. PMID:21073298

  1. Simulation of void formation in interconnect lines

    NASA Astrophysics Data System (ADS)

    Sheikholeslami, Alireza; Heitzinger, Clemens; Puchner, Helmut; Badrieh, Fuad; Selberherr, Siegfried

    2003-04-01

    The predictive simulation of the formation of voids in interconnect lines is important for improving capacitance and timing in current memory cells. The cells considered are used in wireless applications such as cell phones, pagers, radios, handheld games, and GPS systems. In backend processes for memory cells, ILD (interlayer dielectric) materials and processes result in void formation during gap fill. This approach lowers the overall k-value of a given metal layer and is economically advantageous. The effect of the voids on the overall capacitive load is tremendous. In order to simulate the shape and positions of the voids and thus the overall capacitance, the topography simulator ELSA (Enhanced Level Set Applications) has been developed which consists of three modules, a level set module, a radiosity module, and a surface reaction module. The deposition process considered is deposition of silicon nitride. Test structures of interconnect lines of memory cells were fabricated and several SEM images thereof were used to validate the corresponding simulations.

  2. 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.

  3. Dynamic Void Growth and Shrinkage in Mg under Electron Irradiation

    SciTech Connect

    Xu, W. Z.; Zhang, Y. F.; Cheng, G. M.; Jian, W. W.; Millett, P. C.; Koch, C. C.; Mathaudhu, S. N.; Zhu, Y. T.

    2014-04-30

    We report in-situ atomic-scale investigation of void evolution, including growth, coalescence and shrinkage, under electron irradiation. With increasing irradiation dose, the total volume of voids increased linearly, while nucleation rate of new voids decreased slightly, and the total number of voids decreased. Some voids continued to grow while others shrank to disappear, depending on the nature of their interactions with nearby self-interstitial loops. For the first time, surface diffusion of adatoms was observed largely responsible for the void coalescence and thickening. These findings provide fundamental understanding to help with the design and modeling of irradiation-resistant materials.

  4. 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.

  5. Gravitational entropy of local cosmic voids

    NASA Astrophysics Data System (ADS)

    Sussman, Roberto A.; Larena, Julien

    2015-08-01

    We undertake a non-perturbative study of the evolution of the ‘gravitational entropy’ proposed by Clifton, Ellis and Tavakol (CET) on local expanding cosmic CDM voids of ˜50-100 Mpc size described as spherical under-dense regions with negative spatial curvature, whose dynamics is determined by Lemaître-Tolman-Bondi (LTB) dust models asymptotic to three different types of FLRW background: ΛCDM, Einstein-de Sitter and ‘open’ FLRW with Λ =0 and negative spatial curvature. By assuming generic nearly spatially flat and linear initial conditions at the last scattering time, we examine analytically and numerically the CET entropy evolution into a fully nonlinear regime in our present cosmic time and beyond. Both analytic and numerical analysis reveal that the late time CET entropy growth is determined by the amplitude of initial fluctuations of spatial curvature at the last scattering time. This entropy growth decays to zero in the late asymptotic time range for all voids, but at a faster rate in voids with ΛCDM and open FLRW backgrounds. However, only for voids in a ΛCDM background is this suppression sufficiently rapid for the CET entropy itself to reach a terminal equilibrium (or ‘saturation’) value. The CET gravitational temperature vanishes asymptotically if Λ =0 and becomes asymptotically proportional to Λ for voids in a ΛCDM background. In the linear regime of the LTB evolution our results coincide, qualitatively and quantitatively, with previous results based on linear perturbation theory.

  6. BetaVoid: molecular voids via beta-complexes and Voronoi diagrams.

    PubMed

    Kim, Jae-Kwan; Cho, Youngsong; Laskowski, Roman A; Ryu, Seong Eon; Sugihara, Kokichi; Kim, Deok-Soo

    2014-09-01

    Molecular external structure is important for molecular function, with voids on the surface and interior being one of the most important features. Hence, recognition of molecular voids and accurate computation of their geometrical properties, such as volume, area and topology, are crucial, yet most popular algorithms are based on the crude use of sampling points and thus are approximations even with a significant amount of computation. In this article, we propose an analytic approach to the problem using the Voronoi diagram of atoms and the beta-complex. The correctness and efficiency of the proposed algorithm is mathematically proved and experimentally verified. The benchmark test clearly shows the superiority of BetaVoid to two popular programs: VOIDOO and CASTp. The proposed algorithm is implemented in the BetaVoid program which is freely available at the Voronoi Diagram Research Center (http://voronoi.hanyang.ac.kr). PMID:24677176

  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. Assembly of filamentary void galaxy configurations

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    We study the formation and evolution of filamentary configurations of dark matter haloes in voids. Our investigation uses the high-resolution Λ cold dark matter simulation CosmoGrid to look for void systems resembling the VGS_31 elongated system of three interacting galaxies that was recently discovered by the Void Galaxy Survey inside a large void in the Sloan Digital Sky Survey galaxy redshift survey. H I data revealed these galaxies to be embedded in a common elongated envelope, possibly embedded in intravoid filament. In the CosmoGrid simulation we look for systems similar to VGS_31 in mass, size and environment. We find a total of eight such systems. For these systems, we study the distribution of neighbour haloes, the assembly and evolution of the main haloes and the dynamical evolution of the haloes, as well as the evolution of the large-scale structure in which the systems are embedded. The spatial distribution of the haloes follows that of the dark matter environment. We find that VGS_31-like systems have a large variation in formation time, having formed between 10 Gyr ago and the present epoch. However, the environments in which the systems are embedded evolved to resemble each other substantially. Each of the VGS_31-like systems is embedded in an intravoid wall, that no later than z = 0.5 became the only prominent feature in its environment. While part of the void walls retain a rather featureless character, we find that around half of them are marked by a pronounced and rapidly evolving substructure. Five haloes find themselves in a tenuous filament of a few h-1 Mpc long inside the intravoid wall. Finally, we compare the results to observed data from VGS_31. Our study implies that the VGS_31 galaxies formed in the same (proto)filament, and did not meet just recently. The diversity amongst the simulated halo systems indicates that VGS_31 may not be typical for groups of galaxies in voids.

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 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. An Observational Detection of the Bridge Effect of Void Filaments

    NASA Astrophysics Data System (ADS)

    Shim, Junsup; Lee, Jounghun; Hoyle, Fiona

    2015-12-01

    The bridge effect of void filaments is a phrase coined by Park & Lee to explain the correlations found in a numerical experiment between the luminosity of the void galaxies and the degree of straightness of their host filaments. Their numerical finding implies that a straight void filament provides a narrow channel for the efficient transportation of gas and matter particles from the surroundings into void galaxies. Analyzing the Sloan void catalog constructed by Pan et al., we identify the filamentary structures in void regions and determine the specific size of each void filament as a measure of its straightness. To avoid possible spurious signals caused by Malmquist bias, we consider only those void filaments whose redshifts are in the range 0≤slant z≤slant 0.02 and find a clear tendency that the void galaxies located in the straighter filaments are on average more luminous, which is in qualitative agreement with the numerical prediction. It is also shown that the strength of correlation increases with the number of member galaxies in the void filaments, which can be understood physically on the grounds that the more stretched filaments can connect the dense surroundings even to galaxies located deep in the central parts of the voids. This observational evidence may provide a key clue to the puzzling issue of why the void galaxies have higher specific star formation rates and bluer colors than their wall counterparts.

  11. 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...

  12. Void Coalescence Processes Quantified Through Atomistic and Multiscale Simulation

    SciTech Connect

    Rudd, R E; Seppala, E T; Dupuy, L M; Belak, J

    2007-01-12

    Simulation of ductile fracture at the atomic scale reveals many aspects of the fracture process including specific mechanisms associated with void nucleation and growth as a precursor to fracture and the plastic deformation of the material surrounding the voids and cracks. Recently we have studied void coalescence in ductile metals using large-scale atomistic and continuum simulations. Here we review that work and present some related investigations. The atomistic simulations involve three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. No pronounced shear flow is found in the coalescence process. We also discuss a technique for optimizing the calculation of fine-scale information on the fly for use in a coarse-scale simulation, and discuss the specific case of a fine-scale model that calculates void growth explicitly feeding into a coarse-scale mechanics model to study damage localization.

  13. 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.

  14. Remote infrared thermal sensing of sewer voids

    NASA Astrophysics Data System (ADS)

    Weil, Gary J.

    1995-05-01

    Many sewers in America's cities are more than 125 years old and are subject to structural failure. In one year alone, St. Louis, Missouri had 4,000 sewer collapses that carried an astronomical repair tag. When a sewer caves in, it often takes the street, sidewalks, and surrounding buildings along with it endangering public health and safety. The ideal situation would be to repair a sewer before such cave-ins occur, as emergency repairs are far more costly than preventive measures. The question addressed by this paper is how to detect unseen problem areas in sewer systems before collapses occur. At the present, progressive sewer administrations may use crawl crews or remote controlled video cameras to inspect sewers at suspected problem locations. This can be extremely costly, dangerous, and not very accurate, as a void around the outside of the sewer is often invisible from within. Thus, even a crawl crew can fail to detect most voids. Sewer districts and independent engineering firms have found infrared thermography, a nondestructive testing method, to be extremely accurate in finding sewer voids, and accompanying pipeline leaks, before they can cause expensive and dangerous problems. Infrared thermography is a non-contact, remote sensing method, with the potential for surveying large areas quickly and efficiently.

  15. Revisiting the Simplified Bernoulli Equation

    PubMed Central

    Heys, Jeffrey J; Holyoak, Nicole; Calleja, Anna M; Belohlavek, Marek; Chaliki, Hari P

    2010-01-01

    Background: The assessment of the severity of aortic valve stenosis is done by either invasive catheterization or non-invasive Doppler Echocardiography in conjunction with the simplified Bernoulli equation. The catheter measurement is generally considered more accurate, but the procedure is also more likely to have dangerous complications. Objective: The focus here is on examining computational fluid dynamics as an alternative method for analyzing the echo data and determining whether it can provide results similar to the catheter measurement. Methods: An in vitro heart model with a rigid orifice is used as a first step in comparing echocardiographic data, which uses the simplified Bernoulli equation, catheterization, and echocardiographic data, which uses computational fluid dynamics (i.e., the Navier-Stokes equations). Results: For a 0.93cm2 orifice, the maximum pressure gradient predicted by either the simplified Bernoulli equation or computational fluid dynamics was not significantly different from the experimental catheter measurement (p > 0.01). For a smaller 0.52cm2 orifice, there was a small but significant difference (p < 0.01) between the simplified Bernoulli equation and the computational fluid dynamics simulation, with the computational fluid dynamics simulation giving better agreement with experimental data for some turbulence models. Conclusion: For this simplified, in vitro system, the use of computational fluid dynamics provides an improvement over the simplified Bernoulli equation with the biggest improvement being seen at higher valvular stenosis levels. PMID:21625471

  16. The sparkling Universe: the coherent motions of cosmic voids

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    We compute the bulk motions of cosmic voids, using a Λ cold dark matter numerical simulation considering the mean velocities of the dark matter inside the void itself and that of the haloes in the surrounding shell. We find coincident values of these two measures in the range ˜300-400 km s-1, not far from the expected mean peculiar velocities of groups and galaxy clusters. When analysing the distribution of the pairwise relative velocities of voids, we find a remarkable bimodal behaviour consistent with an excess of both systematically approaching and receding voids. We determine that the origin of this bimodality resides in the void large-scale environment, since once voids are classified into void-in-void (R-type) or void-in-cloud (S-type), R-types are found mutually receding away, while S-types approach each other. The magnitude of these systematic relative velocities account for more than 100 km s-1, reaching large coherence lengths of up to 200 h-1 Mpc . We have used samples of voids from the Sloan Digital Sky Survey Data Release 7 and the peculiar velocity field inferred from linear theory, finding fully consistent results with the simulation predictions. Thus, their relative motion suggests a scenario of a sparkling universe, with approaching and receding voids according to their local environment.

  17. Electrochemical effects of isolated voids in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Hassan, A.-R.; El-Azab, Anter; Manuel, Michele

    2014-04-01

    We present a model to study the electrochemical effects of voids in oxide materials under equilibrium conditions and apply this model to uranium dioxide. Based on thermodynamic arguments, we claim that voids in uranium dioxide must contain oxygen gas at a pressure that we determine via a Kelvin equation in terms of temperature, void radius and the oxygen pressure of the outside gas reservoir in equilibrium with the oxide. The oxygen gas within a void gives rise to ionosorption and the formation of a layer of surface-charge on the void surface, which, in turn, induces an influence zone of space charge into the matrix surrounding the void. Since the space charge is carried in part by atomic defects, it is concluded that, as a part of the thermodynamic equilibrium of oxides containing voids, the off-stoichiometry around the void is different from its remote bulk value. As such, in a uranium dioxide solid with a void ensemble, the average off-stoichiometry level in the material differs from that of the void-free counterpart. The model is applied to isolated voids in off-stoichiometric uranium dioxide for a wide range of temperature and disorder state of the oxide.

  18. Void Coalescence Processes Quantified through Atomistic and Multiscale Simulation

    SciTech Connect

    Rudd, R E; Seppala, E T; Dupuy, L M; Belak, J

    2005-12-31

    Simulation of ductile fracture at the atomic scale reveals many aspects of the fracture process including specific mechanisms associated with void nucleation and growth as a precursor to fracture and the plastic deformation of the material surrounding the voids and cracks. Recently we have studied void coalescence in ductile metals using large-scale atomistic and continuum simulations. Here we review that work and present some related investigations. The atomistic simulations involve three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. No pronounced shear flow is found in the coalescence process.

  19. On the observability of coupled dark energy with cosmic voids

    NASA Astrophysics Data System (ADS)

    Sutter, P. M.; Carlesi, Edoardo; Wandelt, Benjamin D.; Knebe, Alexander

    2015-01-01

    Taking N-body simulations with volumes and particle densities tuned to match the sloan digital sky survey DR7 spectroscopic main sample, we assess the ability of current void catalogues to distinguish a model of coupled dark matter-dark energy from Λ cold dark matter cosmology using properties of cosmic voids. Identifying voids with the VIDE toolkit, we find no statistically significant differences in the ellipticities, but find that coupling produces a population of significantly larger voids, possibly explaining the recent result of Tavasoli et al. In addition, we use the universal density profile of Hamaus et al. to quantify the relationship between coupling and density profile shape, finding that the coupling produces broader, shallower, undercompensated profiles for large voids by thinning the walls between adjacent medium-scale voids. We find that these differences are potentially measurable with existing void catalogues once effects from survey geometries and peculiar velocities are taken into account.

  20. [Voiding dysfunction in children aged five to 15 years].

    PubMed

    Karaklajić, Dragana; Peco-Antić, Amira

    2004-01-01

    Voiding dysfunction in children was analyzed in 91 patients in a period from January 1st to October 1st 1998. Most of the patients had functional voiding disorder (92.31%), and only 7.69% manifested monosymptomatic night enuresis. The number of girls was bigger in the group of patients with voiding dysfunction while the boys were predominant in the group with monosymptomatic nocturnal enuresis. More than a half of children with functional voiding disorder had repeated urinal infections (58.23%), incontinence (93.49%), need for urgent voiding (68.13%), and vesicoureteral reflux (47.61%). The most common type of voiding dysfunction was urge syndrome/urge incontinence. The incidence of dysfunctional voiding disorder was more often in children with scaring changes of kidney which were diagnosed by static scintigraphy. PMID:15794052

  1. Visualization and void fraction measurement of decompressed boiling flow in a capillary tube

    NASA Astrophysics Data System (ADS)

    Asano, H.; Murakawa, H.; Takenaka, N.; Takiguchi, K.; Okamoto, M.; Tsuchiya, T.; Kitaide, Y.; Maruyama, N.

    2011-09-01

    A capillary tube is often used as a throttle for a refrigerating cycle. Subcooled refrigerant usually flows from a condenser into the capillary tube. Then, the refrigerant is decompressed along the capillary tube. When the static pressure falls below the saturation pressure for the liquid temperature, spontaneous boiling occurs. A vapor-liquid two-phase mixture is discharged from the tube. In designing a capillary tube, it is necessary to calculate the flow rate for given boundary conditions on pressure and temperature at the inlet and exit. Since total pressure loss is dominated by frictional and acceleration losses during two-phase flow, it is first necessary to specify the boiling inception point. However, there will be a delay in boiling inception during decompressed flow. This study aimed to clarify the boiling inception point and two-phase flow characteristics of refrigerant in a capillary tube. Refrigerant flows in a coiled copper capillary tube were visualized by neutron radiography. The one-dimensional distribution of volumetric average void fraction was measured from radiographs through image processing. From the void fraction distribution, the boiling inception point was determined. Moreover, a simplified CT method was successfully applied to a radiograph for cross-sectional measurements. The experimental results show the flow pattern transition from intermittent flow to annular flow that occurred at a void fraction of about 0.45.

  2. Void forming pyrolytic carbon coating process

    DOEpatents

    Beatty, Ronald L.; Cook, Jackie L.

    2000-01-01

    A pyrolytic carbon coated nuclear fuel particle and method of making it. The fuel particle has a core composed of a refractory compound of an actinide metal. The pyrolytic carbon coating surrounds the core so as to provide a void volume therebetween. The coating has an initial density of no greater than 1.45 grams/cm.sup.3 and an anisotropy factor than 3.0 and a final density upon heat treatment above about 2000.degree. C. of greater than 1.7 grams/cm.sup.3 and an anisotropy factor greater than 5.

  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. PMID:27261790

  4. Void forming pyrolytic carbon coating process

    SciTech Connect

    Beatty, R.L.; Cook, J.L.

    2000-06-27

    A pyrolytic carbon coated nuclear fuel particle and method of making it are disclosed. The fuel particle has a core composed of a refractory compound of an actinide metal. The pyrolytic carbon coating surrounds the core so as to provide a void volume therebetween. The coating has an initial density of no greater than 1.45 grams/cm{sup 3} and an anisotropy factor than 3.0 and a final density upon heat treatment above about 2,000 C of greater than 1.7 grams/cm{sup 3} and an anisotropy factor greater than 5.

  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. Electrical Resistivity Monitoring of Voids: Results of Dynamic Modeling Experiments

    NASA Astrophysics Data System (ADS)

    Lane, J. W.; Day-Lewis, F. D.; Singha, K.

    2006-05-01

    Remote, non-invasive detection of voids is a challenging problem for environmental and engineering investigations in karst terrain. Many geophysical methods including gravity, electrical, electromagnetic, magnetic, and seismic have potential to detect voids in the subsurface; lithologic heterogeneity and method- specific sources of noise, however, can mask the geophysical signatures of voids. New developments in automated, autonomous geophysical monitoring technology now allow for void detection using differential geophysics. We propose automated collection of electrical resistivity measurements over time. This dynamic approach exploits changes in subsurface electrical properties related to void growth or water-table fluctuation in order to detect voids that would be difficult or impossible to detect using static imaging approaches. We use a series of synthetic modeling experiments to demonstrate the potential of difference electrical resistivity tomography for finding (1) voids that develop vertically upward under a survey line (e.g., an incipient sinkhole); (2) voids that develop horizontally toward a survey line (e.g., a tunnel); and (3) voids that are influenced by changing hydrologic conditions (e.g., void saturation and draining). Synthetic datasets are simulated with a 3D finite-element model, but the inversion assumes a 2D forward model to mimic conventional practice. The results of the synthetic modeling experiments provide insights useful for planning and implementing field-scale monitoring experiments using electrical methods.

  7. Nanometer voids prevent crack growth in polymer thin films

    NASA Astrophysics Data System (ADS)

    Yokoyama, Hideaki; Dutriez, Cedric; Satoh, Kotaro; Kamigaito, Masami

    2007-03-01

    Macroscopic voids initiate cracks and cause catastrophic failure in brittle materials. The effect of micrometer voids in the mechanical properties of polymeric materials was studied in 1980's and 90's with the expectation that such small voids may initiate crazing, the toughening mechanism in polymer solids, similar to dispersed rubber particles widely used in industry. However, the micrometer voids showed only limited resistance against crack growth, and it was concluded that much smaller voids are necessary for the drastic change in mechanical properties. We have recently succeeded the nondestructive introduction of nanometer voids (30--70 nm) in polymeric materials using block copolymer template and carbon dioxide (CO2) by partitioning CO2 in CO2-philic nanodomains of block copolymers. The reduction of Young's modulus with such nanometer voids was minimal (2 to 1 GPa) due to the (short-range) ordered spherical voids. While the unprocessed copolymer films failed in brittle manner at around 2 % of tensile strain, the processed copolymer films with nanometer voids did not break up to at least 60 %. A microscopic observation under strain of the crack tip revealed that the nanometer voids were deformed under strain and directly converted into the networked fibrils near the crack tip similar to crazing and thus prevented the crack growth.

  8. 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

  9. Breather mechanism of the void ordering in crystals under irradiation

    NASA Astrophysics Data System (ADS)

    Dubinko, Vladimir

    2009-09-01

    The void ordering has been observed in very different radiation environments ranging from metals to ionic crystals. In the present paper the ordering phenomenon is considered as a consequence of the energy transfer along the close packed directions provided by self-focusing discrete breathers. The self-focusing breathers are energetic, mobile and highly localized lattice excitations that propagate great distances in atomic-chain directions in crystals. This points to the possibility of atoms being ejected from the void surface by the breather-induced mechanism, which is similar to the focuson-induced mechanism of vacancy emission from voids proposed in our previous paper. The main difference between focusons and breathers is that the latter are stable against thermal motion. There is evidence that breathers can occur in various crystals, with path lengths ranging from 104 to 107 unit cells. Since the breather propagating range can be larger than the void spacing, the voids can shield each other from breather fluxes along the close packed directions, which provides a driving force for the void ordering. Namely, the vacancy emission rate for "locally ordered" voids (which have more immediate neighbors along the close packed directions) is smaller than that for the "interstitial" ones, and so they have some advantage in growth. If the void number density is sufficiently high, the competition between them makes the "interstitial" voids shrink away resulting in the void lattice formation. The void ordering is intrinsically connected with a saturation of the void swelling, which is shown to be another important consequence of the breather-induced vacancy emission from voids.

  10. 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.

  11. A Simple Gravitational Lens Model for Cosmic Voids

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu

    2015-05-01

    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 ˜10-2 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-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.

  12. Structure of void space in polymer solutions.

    PubMed

    Sung, Bong June; Yethiraj, Arun

    2010-03-01

    The structure of void space in two- and three-dimensional (3D) polymer solutions is studied using Voronoi tessellation and percolation theory. The polymer molecules are modeled as freely jointed chains of N tangent hard disks (two dimensions) or spheres (three dimensions). Polymer chains are equilibrated via Monte Carlo simulations and the pore space in configurations of equilibrated chains is mapped using Voronoi tessellation. In d dimensions a Voronoi vertex is the center of the sphere tangent to the d+1 nearest monomers. An edge of the Voronoi diagram is the shortest route between two neighboring vertices. The edge is considered connected if a monomer can pass through and disconnected otherwise. The Voronoi construction is used to calculate the percolation threshold of the void space. The most interesting result is that the polymer area fraction at the percolation threshold is a nonmonotonic function of N in two dimensions but monotonically reaches a constant value in three dimensions. The crossover behavior of the percolation threshold is also observed in pseudo-3D. The pore size distribution decreases monotonically with increasing pore size. This is markedly different from that in configurations of hard disks (monomeric fluid) where the pore size distribution is peaked at finite size. PMID:20365759

  13. Control of Urinary Drainage and Voiding

    PubMed Central

    2015-01-01

    Urine differs greatly in ion and solute composition from plasma and contains harmful and noxious substances that must be stored for hours and then eliminated when it is socially convenient to do so. The urinary tract that handles this output is composed of a series of pressurizable muscular compartments separated by sphincteric structures. With neural input, these structures coordinate the delivery, collection, and, ultimately, expulsion of urine. Despite large osmotic and chemical gradients in this waste fluid, the bladder maintains a highly impermeable surface in the face of a physically demanding biomechanical environment, which mandates recurring cycles of surface area expansion and increased wall tension during filling, followed by rapid wall compression during voiding. Afferent neuronal inflow from mucosa and submucosa communicates sensory information about bladder fullness, and voiding is initiated consciously through coordinated central and spinal efferent outflow to the detrusor, trigonal internal sphincter, and external urethral sphincter after periods of relative quiescence. Provocative new findings suggest that in some cases, lower urinary tract symptoms, such as incontinence, urgency, frequency, overactivity, and pain may be viewed as a consequence of urothelial defects (either urothelial barrier breakdown or inappropriate signaling from urothelial cells to underlying sensory afferents and potentially interstitial cells). This review describes the physiologic and anatomic mechanisms by which urine is moved from the kidney to the bladder, stored, and then released. Relevant clinical examples of urinary tract dysfunction are also discussed. PMID:24742475

  14. Early voiding dysfunction associated with prostate brachytherapy.

    PubMed

    Wagner; Nag; Young; Bahnson

    2000-12-15

    Introduction: Transperineal prostate brachytherapy is gaining popularity as a treatment for clinically localized carcinoma of the prostate. Very little prospective data exists addressing the issue of complications associated with this procedure. We present an analysis of the early voiding dysfunction associated with prostate brachytherapy. Materials and Methods: Forty-six consecutive patients who underwent Palladium-103 (Pd-103) seed placement for clinically localized prostate carcinoma were evaluated prospectively for any morbidity associated with the procedure. Twenty-three patients completed an International Prostate Symptom Score (IPSS) questionnaire preoperatively, at their first postoperative visit, and at their second postoperative visit. The total IPSS, each of the seven individual components, and the "bother" score were evaluated separately for each visit, and statistical significance was determined. Results: Urinary retention occurred in 7/46 patients (15%). Of these, 5 were able to void spontaneously after catheter removal. One patient is maintained with a suprapubic tube, and one patient is currently on continuous intermittent catheterization. Baseline IPSS was 7.1 and this went to 20.0 at the first postoperative visit (p<0.001). By the second postoperative visit, the IPSS was 8.0. Conclusions: In our experience, prostate brachytherapy for localized carcinoma of the prostate is associated with a 15% catheterization rate and a significant increase in the IPSS (7.1 to 20.0). This increase in the IPSS seems to be self-limited. Patients need to be educated on these issues prior to prostate brachytherapy. PMID:11113369

  15. An alternative void growth suppression technique in autoclave processing

    SciTech Connect

    White, S.R.; Kim, Y.K.

    1994-12-31

    Voids in composites are primarily controlled by the amount of autoclave pressure applied during the process cycle. There are two reasons that this methodology may not be feasible in all cases. First, the prescribed autoclave pressure may be excessively high and secondly, the resin pressure is not hydrostatic nor uniform throughout the composite part. An alternative method to reduce void content in polymer composites is presented using the stage curing technique. In this processing method the cure cycle is interrupted and the part is cooled down under pressure. During this cool down phase bubble dissolution occurs. Subsequently, the part is heated back up to the cure temperature without vacuum. Bubble growth rate is reduced under these conditions and the final void content is also reduced. Experimental evidence shows a 79% reduction in void content for an AS4/3510-6 composite system. A simple void growth model is used to explain the void reduction mechanism and provide quantitative verification.

  16. Void alignment and density profile applied to measuring cosmological parameters

    NASA Astrophysics Data System (ADS)

    Dai, De-Chang

    2015-12-01

    We study the orientation and density profiles of the cosmological voids with Sloan Digital Sky Survey (SDSS; Ahn et al.) 10 data. Using voids to test Alcock-Paczynski effect has been proposed and tested in both simulations and actual SDSS data. Previous observations imply that there exist an empirical stretching factor which plays an important role in the voids' orientation. Simulations indicate that this empirical stretching factor is caused by the void galaxies' peculiar velocities. Recently Hamaus et al. found that voids' density profiles are universal and their average velocities satisfy linear theory very well. In this paper, we first confirm that the stretching effect exists using independent analysis. We then apply the universal density profile to measure the cosmological parameters. We find that the void density profile can be a tool to measure the cosmological parameters.

  17. The association of age of toilet training and dysfunctional voiding

    PubMed Central

    Hodges, Steve J; Richards, Kyle A; Gorbachinsky, Ilya; Krane, L Spencer

    2014-01-01

    Objective To determine whether age of toilet training is associated with dysfunctional voiding in children. Materials and methods We compared patients referred to the urologic clinics for voiding dysfunction with age-matched controls without urinary complaints. Characteristics including age and reason for toilet training, method of training, and encopresis or constipation were compared between both groups. Results Initiation of toilet training prior to 24 months and later than 36 months of age were associated with dysfunctional voiding. However, dysfunctional voiding due to late toilet training was also associated with constipation. Conclusion Dysfunctional voiding may be due to delayed emptying of the bowel and bladder by children. The symptoms of dysfunctional voiding are more common when toilet training early, as immature children may be less likely to empty in a timely manner, or when training late due to (or in association with) constipation. PMID:25328866

  18. Simplified High-Power Inverter

    NASA Technical Reports Server (NTRS)

    Edwards, D. B.; Rippel, W. E.

    1984-01-01

    Solid-state inverter simplified by use of single gate-turnoff device (GTO) to commutate multiple silicon controlled rectifiers (SCR's). By eliminating conventional commutation circuitry, GTO reduces cost, size and weight. GTO commutation applicable to inverters of greater than 1-kilowatt capacity. Applications include emergency power, load leveling, drives for traction and stationary polyphase motors, and photovoltaic-power conditioning.

  19. 75 FR 28223 - Simplified Proceedings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-20

    ... From the Federal Register Online via the Government Publishing Office ] FEDERAL MINE SAFETY AND HEALTH REVIEW COMMISSION 29 CFR Part 2700 Simplified Proceedings AGENCY: Federal Mine Safety and Health Review Commission. ACTION: Notice of proposed rulemaking. SUMMARY: The Federal Mine Safety and...

  20. Simplifying the Water Poverty Index

    ERIC Educational Resources Information Center

    Cho, Danny I.; Ogwang, Tomson; Opio, Christopher

    2010-01-01

    In this paper, principal components methodology is used to derive simplified and cost effective indexes of water poverty. Using a well known data set for 147 countries from which an earlier five-component water poverty index comprising of "Resources," "Access," "Capacity," "Use" and "Environment" was constructed, we find that a simplified…

  1. A hierarchy of voids: more ado about nothing

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem; Lam, Tsz Yan; Sheth, Ravi K.

    2012-02-01

    We extend earlier work on the problem of estimating the void-volume function - the abundance and evolution of large voids which grow gravitationally in an expanding universe - in two ways. The first removes an ambiguity about how the void-in-cloud process, which erases small voids, should be incorporated into the excursion set approach. The main technical change here is to think of voids within a fully Eulerian, rather than purely Lagrangian, framework. The second accounts for correlations between different spatial scales in the initial conditions. We provide numerical and analytical arguments showing how and why both changes modify the predicted abundances substantially. In particular, we show that the predicted importance of the void-in-cloud process depends strongly on whether or not one accounts for correlations between scales. With our new formulation, the void-in-cloud process dramatically reduces the predicted abundances of voids if such correlations are ignored, but only matters for the smallest voids in the more realistic case in which the spatial correlations are included.

  2. 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.

  3. Reconciling the local void with the CMB

    SciTech Connect

    Nadathur, Seshadri; Sarkar, Subir

    2011-03-15

    In the standard cosmological model, the dimming of distant Type Ia supernovae is explained by invoking the existence of repulsive ''dark energy'' which is causing the Hubble expansion to accelerate. However, this may be an artifact of interpreting the data in an (oversimplified) homogeneous model universe. In the simplest inhomogeneous model which fits the SNe Ia Hubble diagram without dark energy, we are located close to the center of a void modeled by a Lemaitre-Tolman-Bondi metric. It has been claimed that such models cannot fit the cosmic microwave background (CMB) and other cosmological data. This is, however, based on the assumption of a scale-free spectrum for the primordial density perturbation. An alternative physically motivated form for the spectrum enables a good fit to both SNe Ia (Constitution/Union2) and CMB (WMAP 7-yr) data, and to the locally measured Hubble parameter. Constraints from baryon acoustic oscillations and primordial nucleosynthesis are also satisfied.

  4. 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.

  5. The void galaxy survey: Star formation properties

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We study the star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Current star formation rates are derived from H α and recent star formation rates from near-UV imaging. In addition, infrared 3.4, 4.6, 12 and 22 μm Wide-field Infrared Survey Explorer emission is used as star formation and mass indicator. Infrared and optical colours show that the VGS sample displays a wide range of dust and metallicity properties. We combine these measurements with stellar and H I masses to measure the specific SFRs (SFR/M*) and star formation efficiencies ({SFR/{M }_H I}). We compare the star formation properties of our sample with galaxies in the more moderate density regions of the cosmic web, `the field'. We find that specific SFRs of the VGS galaxies as a function of stellar and H I mass are similar to those of the galaxies in these field regions. Their SFR α is slightly elevated than the galaxies in the field for a given total H I mass. In the global star formation picture presented by Kennicutt-Schmidt, VGS galaxies fall into the regime of low average star formation and correspondingly low H I surface density. Their mean {SFR α /{M}_{H I} and SFR α/M* are of the order of 10- 9.9 yr- 1. We conclude that while the large-scale underdense environment must play some role in galaxy formation and growth through accretion, we find that even with respect to other galaxies in the more mildly underdense regions, the increase in star formation rate is only marginal.

  6. Luminosity distance in 'Swiss cheese' cosmology with randomized voids. I. Single void size

    SciTech Connect

    Vanderveld, R. Ali; Flanagan, Eanna E.; Wasserman, Ira

    2008-10-15

    Recently, there have been suggestions that the Type Ia supernova data can be explained using only general relativity and cold dark matter with no dark energy. In 'Swiss cheese' models of the Universe, the standard Friedmann-Robertson-Walker picture is modified by the introduction of mass-compensating spherical inhomogeneities, typically described by the Lemaitre-Tolman-Bondi metric. If these inhomogeneities correspond to underdense cores surrounded by mass-compensating overdense shells, then they can modify the luminosity distance-redshift relation in a way that can mimic accelerated expansion. It has been argued that this effect could be large enough to explain the supernova data without introducing dark energy or modified gravity. We show that the large apparent acceleration seen in some models can be explained in terms of standard weak field gravitational lensing together with insufficient randomization of void locations. The underdense regions focus the light less than the homogeneous background, thus dimming supernovae in a way that can mimic the effects of acceleration. With insufficient randomization of the spatial location of the voids and of the lines of sight, coherent defocusing can lead to anomalously large demagnification effects. We show that a proper randomization of the voids and lines of sight reduces the effect to the point that it can no longer explain the supernova data.

  7. 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.

  8. Void fraction measurements by quick acting valves and capacitance measurements

    NASA Astrophysics Data System (ADS)

    Chang, Jae H.; Best, Frederick R.

    1998-01-01

    Two-phase flow systems are widely estimated to have superior capability in comparison with single-phase thermal management systems for spacecraft. However, microgravity two-phase flow technology is insufficiently advanced to allow development with acceptable risk levels. A capacitance effect, void fraction measurement sensor has been developed by Creare Inc. to begin to satisfy microgravity technology needs. Under a NASA Johnson Space Center grant, microgravity tests of the capacitance void fraction sensors were performed aboard the NASA KC-135. Twelve KC-135 flights were conducted in three series. Test points were collected over a wide range of void fractions (0%-90%). Data were collected from stratified, slug, and annular flow regimes. Void fraction measurements from the capacitance sensors were compared with the void fractions from a trapped volume in the test section between two quick acting valves. Under the annular flow regime, void fractions measured by the capacitance sensors compared well with values from the trapped volume. In slug flow regime, some discrepancies between the sensors and trapped volumes were found. However, when the working fluid (Suva) mass flow rate increased from 0.00314 kg/s to 0.007756 kg/s, the void fraction measurements between the capacitance sensors and the trapped volume had better agreement. Overall, the FRIM experimental package produced satisfactory test conditions in the microgravity conditions of the KC-135 aircraft, to validate and calibrate the Creare capacitance void fraction sensors.

  9. 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.

  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. 43 CFR 3.7 - Permit to become void.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Permit to become void. 3.7 Section 3.7 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.7 Permit to become void. Failure to begin work under a permit within 6 months after it is granted,...

  12. 43 CFR 3.7 - Permit to become void.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Permit to become void. 3.7 Section 3.7 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.7 Permit to become void. Failure to begin work under a permit within 6 months after it is granted,...

  13. 43 CFR 3.7 - Permit to become void.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Permit to become void. 3.7 Section 3.7 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.7 Permit to become void. Failure to begin work under a permit within 6 months after it is granted,...

  14. 43 CFR 3.7 - Permit to become void.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Permit to become void. 3.7 Section 3.7 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.7 Permit to become void. Failure to begin work under a permit within 6 months after it is granted,...

  15. 43 CFR 3.7 - Permit to become void.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Permit to become void. 3.7 Section 3.7 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.7 Permit to become void. Failure to begin work under a permit within 6 months after it is granted,...

  16. Warmth elevating the depths: shallower voids with warm dark matter

    NASA Astrophysics Data System (ADS)

    Yang, Lin F.; Neyrinck, Mark C.; Aragón-Calvo, Miguel A.; Falck, Bridget; Silk, Joseph

    2015-08-01

    Warm dark matter (WDM) has been proposed as an alternative to cold dark matter (CDM), to resolve issues such as the apparent lack of satellites around the Milky Way. Even if WDM is not the answer to observational issues, it is essential to constrain the nature of the dark matter. The effect of WDM on haloes has been extensively studied, but the small-scale initial smoothing in WDM also affects the present-day cosmic web and voids. It suppresses the cosmic `sub-web' inside voids, and the formation of both void haloes and subvoids. In N-body simulations run with different assumed WDM masses, we identify voids with the ZOBOV algorithm, and cosmic-web components with the ORIGAMI algorithm. As dark-matter warmth increases (i.e. particle mass decreases), void density minima grow shallower, while void edges change little. Also, the number of subvoids decreases. The density field in voids is particularly insensitive to baryonic physics, so if void density profiles and minima could be measured observationally, they would offer a valuable probe of the nature of dark matter. Furthermore, filaments and walls become cleaner, as the substructures in between have been smoothed out; this leads to a clear, mid-range peak in the density PDF.

  17. Simplifying plasma chemistry via ILDM

    NASA Astrophysics Data System (ADS)

    Rehman, T.; Kemaneci, E.; Graef, W.; van Dijk, J.

    2016-02-01

    A plasma fluid model containing a large number of chemical species and reactions yields a high computational load. One of the methods to overcome this difficulty is to apply Chemical Reduction Techniques as used in combustion engineering. The chemical reduction technique that we study here is ILDM (Intrinsic Lower Dimensional Manifold). The ILDM method is used to simplify an argon plasma model and then a comparison is made with a CRM (Collisional Radiative Model).

  18. A Simplified Adiabatic Compression Apparatus

    NASA Astrophysics Data System (ADS)

    Moloney, Michael J.; McGarvey, Albert P.

    2007-10-01

    Mottmann described an excellent way to measure the ratio of specific heats for air (γ = Cp/Cv) by suddenly compressing a plastic 2-liter bottle. His arrangement can be simplified so that no valves are involved and only a single connection needs to be made. This is done by adapting the plastic cap of a 2-liter plastic bottle so it connects directly to a Vernier Software Gas Pressure Sensor2 and the LabPro3 interface.

  19. Dust-void formation in a dc glow discharge.

    PubMed

    Fedoseev, A V; Sukhinin, G I; Dosbolayev, M K; Ramazanov, T S

    2015-08-01

    Experimental investigations of dusty plasma parameters of a dc glow discharge were performed in a vertically oriented discharge tube. Under certain conditions, dust-free regions (voids) were formed in the center of the dust particle clouds that levitated in the strong electric field of a stratified positive column. A model for radial distribution of dusty plasma parameters of a dc glow discharge in inert gases was developed. The behavior of void formation was investigated for different discharge conditions (type of gas, discharge pressure, and discharge current) and dust particle parameters (particle radii and particle total number). It was shown that it is the ion drag force radial component that leads to the formation of voids. Both experimental and calculated results show that the higher the discharge current the wider dust-free region (void). The calculations also show that more pronounced voids are formed for dust particles with larger radii and under lower gas pressures. PMID:26382534

  20. 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.

  1. 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

    2016-04-01

    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 dependency 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 1,000 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.

  2. DYSFUNCTIONAL URINARY VOIDING IN WOMEN WITH FUNCTIONAL DEFECATORY DISORDERS

    PubMed Central

    Klingele, Christopher J.; Lightner, Deborah J.; Fletcher, J.G.; Gebhart, John B.; Bharucha, Adil E.

    2010-01-01

    Background While pelvic floor dysfunction may manifest with bladder or bowel symptoms, the relationship between functional defecatory disorders and dysfunctional voiding is unclear. Our hypothesis was that patients with defecatory disorders have generalized pelvic floor dysfunction, manifesting as dysfunctional urinary voiding. Methods Voiding was assessed by a symptom questionnaire, a voiding diary, uroflowmetry, and by measuring the postvoid residual urine volume in this case-control study of 28 patients with a functional defecatory disorder (36 ± 2 years, Mean ± SEM) and 30 healthy women (36 ± 2 years). Key Results Women with a defecatory disorder frequently reported urinary symptoms: urgency (61%), frequency (36%), straining to begin (21%), or finish (50%) voiding, and the sense of incomplete emptying (54%). Fluid intake and output, the minimum voided volume, and the shortest duration between voids measured by voiding diaries were higher (p < 0.05) in patients than in controls. Uroflowmetry revealed abnormalities in 7 controls and 22 patients. The risk of abnormal voiding by uroflowmetry was higher in patients (OR 8.0; 95% CI, 2.3–26.9) than in controls. Patients took longer than controls (p< 0.01) to attain the maximum urinary flow rate (12 ± 2 versus 4 ± 0s) and to empty the bladder (29 ± 4 versus 20 ± 2s), but the maximum urinary flow rate and postvoid residual volumes were not significantly different. Conclusions and Inferences Symptoms of dysfunctional voiding and uroflowmetric abnormalities occurred more frequently, suggesting of disordered urination, in women with a defecatory disorder than in healthy controls. PMID:20557469

  3. 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

  4. Neuron Model with Simplified Memristive Ionic Channels

    NASA Astrophysics Data System (ADS)

    Hegab, Almoatazbellah M.; Salem, Noha M.; Radwan, Ahmed G.; Chua, Leon

    2015-06-01

    A simplified neuron model is introduced to mimic the action potential generated by the famous Hodgkin-Huxley equations by using the genetic optimization algorithm. Comparison with different neuron models is investigated, and it is confirmed that the sodium and potassium channels in our simplified neuron model are made out of memristors. In addition, the channel equations in the simplified model may be adjusted to introduce a simplified memristor model that is in accordance with the theoretical conditions of the memristive systems.

  5. Simplified Model for iLIDS IDD

    NASA Technical Reports Server (NTRS)

    Lewis, James L.

    2010-01-01

    The NASA Docking System (NDS) Project has provided simplified volumetric models for use by potential hosts vehicles to assess vehicle integration. It should be noted that the JSC-65795 NDS Interface Definition Document (IDD) takes precedence over this simplified model. The simplified model serves as a graphical representation only. It is therefore important to state that dimensions and tolerances are to be taken from the IDD document and supersede any measurements derived from the provided simplified model geometry.

  6. Results of a search for faint galaxies in voids.

    NASA Astrophysics Data System (ADS)

    Kuhn, B.; Hopp, U.; Elsaesser, H.

    1997-02-01

    We present the results of a search for intrinsically faint galaxies towards three regions with known voids and the Hercules supercluster. The intention was to identify galaxies of low luminosity in order to find possibly a galaxy population in the voids. Within these selected fields we increased the range of observations in comparison with the recent large field surveys which revealed the non-uniform spatial distribution of galaxies. The limiting magnitude was raised by about 5mag, the limiting surface brightness by 2mag/sq.arcsec, and the limiting diameter reduced to less than 1/3. The individual observational data of our sample are published in the previous PaperI (Hopp et al. 1995) which describes our search strategy and contains B and R magnitudes, apparent diameters, redshifts and galaxy types of about 200 newly identified objects. Their luminosity distribution demonstrates a relatively high percentage of dwarfish galaxies. As the essential result of our survey we have to point out that no clear indication of a void-population was found. The majority of our objects lie outside voids in regions where the already known galaxies are concentrated. Some are located in the middle or near the edges of voids. They appear to be rather isolated, their distances to the nearest neighbour are quite large. Only few of our objects seem to be real void galaxies. Even in the three nearest and rather well defined voids we do not find any hitherto unknown galaxy.

  7. 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

  8. On nonlinear excitation of voids in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Nebbat, E.; Annou, R.; Bharuthram, R.

    2007-09-01

    The void, which is a dust-free region inside the dust cloud in the plasma, results from a balance of the electrostatic force and the ion-drag force on a dust particulate that has numerous forms, some of which are based on models whereas others are driven from first principles. To explain the generation of voids, K. Avinash, A. Bhattacharjee, and S. Hu [Phys. Rev. Lett. 90, 075001 (2003)] proposed a time-dependent nonlinear model that describes the void as a result of an instability. We augment this model by incorporating the grain drift and reintroducing the velocity convective term as well as by replacing the modeled ion-drag force by a more accurate one. The analysis is conducted in a spherical configuration. It is revealed that the void formation is a threshold phenomenon, i.e., it depends on the grain size. Furthermore, the void possesses a sharp boundary beyond which the dust density decreases and may present a corrugated aspect. For big size grains, the use of both ion-drag forces leads to voids of the same dimension, though for grains of small sizes, the Avinash force drives voids of a higher dimension. The model shows good agreement with the experiment.

  9. Partial discharges within two spherical voids in an epoxy resin

    NASA Astrophysics Data System (ADS)

    Illias, H. A.; Chen, G.; Bakar, A. H. A.; Mokhlis, H.; Tunio, M. A.

    2013-08-01

    A void in a dielectric insulation material may exist due to imperfection in the insulation manufacturing or long term stressing. Voids have been identified as one of the common sources of partial discharge (PD) activity within an insulation system, such as in cable insulation and power transformers. Therefore, it is important to study PD phenomenon within void cavities in insulation. In this work, a model of PD activity within two spherical voids in a homogeneous dielectric material has been developed using finite element analysis software to study the parameters affecting PD behaviour. The parameters that have been taken into account are the void surface conductivity, electron generation rate and the inception and extinction fields. Measurements of PD activity within two spherical voids in an epoxy resin under ac sinusoidal applied voltage have also been performed. The simulation results have been compared with the measurement data to validate the model and to identify the parameters affecting PD behaviour. Comparison between measurements of PD activity within single and two voids in a dielectric material have also been made to observe the difference of the results under both conditions.

  10. Void collapse under distributed dynamic loading near material interfaces

    NASA Astrophysics Data System (ADS)

    Shpuntova, Galina; Austin, Joanna

    2012-11-01

    Collapsing voids cause significant damage in diverse applications from biomedicine to underwater propulsion to explosives. While shock-induced void collapse has been studied extensively, less attention has been devoted to stress wave loading, which will occur instead if there are mechanisms for wave attenuation or if the impact velocity is relatively low. A set of dynamic experiments was carried out in a model experimental setup to investigate the effect of acoustic heterogeneities in the surrounding medium on void collapse. Two tissue-surrogate polymer materials of varying acoustic properties were used to create flowfield geometries involving a boundary and a void. A stress wave, generated by projectile impact, triggered void collapse in the gelatinous polymer medium. When the length scales of features in the flow field were on the same order of magnitude as the stress wave length scale, the presence of the boundary was found to affect the void collapse process relative to collapse in the absence of a boundary. This effect was quantified for a range of geometries and impact conditions using a two-color, single-frame particle image velocimetry technique. Research supported by NSF Award #0954769, ``CAREER: Dynamics and damage of void collapse in biological materials under stress wave loading'' with Prof. Henning Winter as Program Manager.

  11. On nonlinear excitation of voids in dusty plasmas

    SciTech Connect

    Nebbat, E.; Annou, R.; Bharuthram, R.

    2007-09-15

    The void, which is a dust-free region inside the dust cloud in the plasma, results from a balance of the electrostatic force and the ion-drag force on a dust particulate that has numerous forms, some of which are based on models whereas others are driven from first principles. To explain the generation of voids, K. Avinash, A. Bhattacharjee, and S. Hu [Phys. Rev. Lett. 90, 075001 (2003)] proposed a time-dependent nonlinear model that describes the void as a result of an instability. We augment this model by incorporating the grain drift and reintroducing the velocity convective term as well as by replacing the modeled ion-drag force by a more accurate one. The analysis is conducted in a spherical configuration. It is revealed that the void formation is a threshold phenomenon, i.e., it depends on the grain size. Furthermore, the void possesses a sharp boundary beyond which the dust density decreases and may present a corrugated aspect. For big size grains, the use of both ion-drag forces leads to voids of the same dimension, though for grains of small sizes, the Avinash force drives voids of a higher dimension. The model shows good agreement with the experiment.

  12. Local void and slip model used in BODYFIT-2PE

    SciTech Connect

    Chen, B.C.J.; Chien, T.H.; Kim, J.H.; Lellouche, G.S.

    1983-01-01

    A local void and slip model has been proposed for a two-phase flow without the need of fitting any empirical parameters. This model is based on the assumption that all bubbles have reached their terminal rise velocities in the two-phase region. This simple model seems to provide reasonable calculational results when compared with the experimental data and other void and slip models. It provides a means to account for the void and slip of a two-phase flow on a local basis. This is particularly suitable for a fine mesh thermal-hydraulic computer program such as BODYFIT-2PE.

  13. 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.

  14. Simplifying microbial electrosynthesis reactor design

    PubMed Central

    Giddings, Cloelle G. S.; Nevin, Kelly P.; Woodward, Trevor; Lovley, Derek R.; Butler, Caitlyn S.

    2015-01-01

    Microbial electrosynthesis, an artificial form of photosynthesis, can efficiently convert carbon dioxide into organic commodities; however, this process has only previously been demonstrated in reactors that have features likely to be a barrier to scale-up. Therefore, the possibility of simplifying reactor design by both eliminating potentiostatic control of the cathode and removing the membrane separating the anode and cathode was investigated with biofilms of Sporomusa ovata. S. ovata reduces carbon dioxide to acetate and acts as the microbial catalyst for plain graphite stick cathodes as the electron donor. In traditional ‘H-cell’ reactors, where the anode and cathode chambers were separated with a proton-selective membrane, the rates and columbic efficiencies of microbial electrosynthesis remained high when electron delivery at the cathode was powered with a direct current power source rather than with a potentiostat-poised cathode utilized in previous studies. A membrane-less reactor with a direct-current power source with the cathode and anode positioned to avoid oxygen exposure at the cathode, retained high rates of acetate production as well as high columbic and energetic efficiencies. The finding that microbial electrosynthesis is feasible without a membrane separating the anode from the cathode, coupled with a direct current power source supplying the energy for electron delivery, is expected to greatly simplify future reactor design and lower construction costs. PMID:26029199

  15. Simplifying microbial electrosynthesis reactor design.

    PubMed

    Giddings, Cloelle G S; Nevin, Kelly P; Woodward, Trevor; Lovley, Derek R; Butler, Caitlyn S

    2015-01-01

    Microbial electrosynthesis, an artificial form of photosynthesis, can efficiently convert carbon dioxide into organic commodities; however, this process has only previously been demonstrated in reactors that have features likely to be a barrier to scale-up. Therefore, the possibility of simplifying reactor design by both eliminating potentiostatic control of the cathode and removing the membrane separating the anode and cathode was investigated with biofilms of Sporomusa ovata. S. ovata reduces carbon dioxide to acetate and acts as the microbial catalyst for plain graphite stick cathodes as the electron donor. In traditional 'H-cell' reactors, where the anode and cathode chambers were separated with a proton-selective membrane, the rates and columbic efficiencies of microbial electrosynthesis remained high when electron delivery at the cathode was powered with a direct current power source rather than with a potentiostat-poised cathode utilized in previous studies. A membrane-less reactor with a direct-current power source with the cathode and anode positioned to avoid oxygen exposure at the cathode, retained high rates of acetate production as well as high columbic and energetic efficiencies. The finding that microbial electrosynthesis is feasible without a membrane separating the anode from the cathode, coupled with a direct current power source supplying the energy for electron delivery, is expected to greatly simplify future reactor design and lower construction costs. PMID:26029199

  16. Quantifying Void Ratio in Granular Materials Using Voronoi Tessellation

    NASA Technical Reports Server (NTRS)

    Alshibli, Khalid A.; El-Saidany, Hany A.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Voronoi technique was used to calculate the local void ratio distribution of granular materials. It was implemented in an application-oriented image processing and analysis algorithm capable of extracting object edges, separating adjacent particles, obtaining the centroid of each particle, generating Voronoi polygons, and calculating the local void ratio. Details of the algorithm capabilities and features are presented. Verification calculations included performing manual digitization of synthetic images using Oda's method and Voronoi polygon system. The developed algorithm yielded very accurate measurements of the local void ratio distribution. Voronoi tessellation has the advantage, compared to Oda's method, of offering a well-defined polygon generation criterion that can be implemented in an algorithm to automatically calculate local void ratio of particulate materials.

  17. Void Closure in Complex Plasmas under Microgravity Conditions

    SciTech Connect

    Lipaev, A. M.; Molotkov, V. I.; Fortov, V. E.; Khrapak, A. G.; Naumkin, V. N.; Khrapak, S. A.; Morfill, G. E.; Ivlev, A. V.; Thomas, H. M.; Ivanov, A. I.; Tretschev, S. E.; Padalka, G. I.

    2007-06-29

    We describe the first observation of a void closure in complex plasma experiments under microgravity conditions performed with the Plasma-Kristall (PKE-Nefedov) facility on board the International Space Station. The void--a grain-free region in the central part of the discharge where the complex plasma is generated--has been formed under most of the plasma conditions and thought to be an inevitable effect. However, we demonstrate in this Letter that an appropriate tune of the discharge parameters allows the void to close. This experimental achievement along with its theoretical interpretation opens new perspectives in engineering new experiments with large quasi-isotropic void-free complex plasma clouds in microgravity conditions.

  18. 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.

  19. 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.

  20. A dynamic void growth model governed by dislocation kinetics

    NASA Astrophysics Data System (ADS)

    Wilkerson, J. W.; Ramesh, K. T.

    2014-10-01

    Here we examine the role of dislocation kinetics and substructure evolution on the dynamic growth of voids under very high strain rates, and develop a methodology for accounting for these effects in a computationally efficient manner. In particular, we account for the combined effects of relativistic dislocation drag and an evolving mobile dislocation density on the dynamics of void growth. We compare these effects to the constraints imposed by micro-inertia and discuss the conditions under which each mechanism governs the rate of void growth. The consequences of these constraints may be seen in a number of experimental observations associated with dynamic tensile failure, including the extreme rate-sensitivity of spall strength observed in laser shock experiments, an apparent anomalous temperate dependence of spall strength, and some particular features of void size distributions on spall surfaces.

  1. Voids in neutron-irradiated metals and alloys

    SciTech Connect

    Hendricks, R.W.

    1980-01-01

    Small-angle x-ray and neutron scattering are powerful analytical tools for investigating long-range fluctuations in electron (x-rays) or magnetic moment (neutrons) densities in materials. In recent years they have yielded valuable information about voids, void size distributions, and swelling in aluminum, aluminum alloys, copper, molybdenum, nickel, nickel-aluminum, niobium and niobium alloys, stainless steels, graphite and silicon carbide. In the case of aluminum, information concerning the shape of the voids and the ratio of specific surface energies was obtained. The technique of small-angle scattering and its application to the study of voids is reviewed in the paper. Emphasis is placed on the conditions which limit the applicability of the technique, on the interpretation of the data, and on a comparison of the results obtained with companion techniques such as transmission electron microscopy and bulk density. 8 figures, 41 references.

  2. Simplified compact containment BWR plant

    SciTech Connect

    Heki, H.; Nakamaru, M.; Tsutagawa, M.; Hiraiwa, K.; Arai, K.; Hida, T.

    2004-07-01

    The reactor concept considered in this paper has a small power output, a compact containment and a simplified BWR configuration with comprehensive safety features. The Compact Containment Boiling Water Reactor (CCR), which is being developed with matured BWR technologies together with innovative systems/components, is expected to prove attractive in the world energy markets due to its flexibility in regard to both energy demands and site conditions, its high potential for reducing investment risk and its safety features facilitating public acceptance. The flexibility is achieved by CCR's small power output of 300 MWe class and capability of long operating cycle (refueling intervals). CCR is expected to be attractive from view point of investment due to its simplification/innovation in design such as natural circulation core cooling with the bottom located short core, internal upper entry control rod drives (CRDs) with ring-type dryers and simplified ECCS system with high pressure containment concept. The natural circulation core eliminates recirculation pumps and the maintenance of such pumps. The internal upper entry CRDs reduce the height of the reactor vessel (RPV) and consequently reduce the height of the primary containment vessel (PCV). The safety features mainly consist of large water inventory above the core without large penetration below the top of the core, passive cooling system by isolation condenser (IC), passive auto catalytic recombiner and in-vessel retention (IVR) capability. The large inventory increases the system response time in the case of design-base accidents, including loss of coolant accidents. The IC suppresses PCV pressure by steam condensation without any AC power. The recombiner decreases hydrogen concentration in the PCV in the case of a severe accident. Cooling the molten core inside the RPV if the core should be damaged by loss of core coolability could attain the IVR. The feasibility of CCR safety system has been confirmed by LOCA

  3. Excursion sets and non-Gaussian void statistics

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

    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. [G. D’Amico, M. Musso, J. Noreña, and A. Paranjape, arXiv:1005.1203.]. However, unlike the excursion set problem for halos which involved random walks in the presence of one barrier δc, the void excursion set problem involves two barriers δv and δc. 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.

  4. Void morphology in polyethylene/carbon black composites

    SciTech Connect

    Marr, D.W.M.; Wartenberg, M.; Schwartz, K.B.

    1996-12-31

    A combination of small angle neutron scattering (SANS) and contrast matching techniques is used to determine the size and quantity of voids incorporated during fabrication of polyethylene/carbon black composites. The analysis used to extract void morphology from SANS data is based on the three-phase model of microcrack determination via small angle x-rayscattering (SAXS) developed by W.Wu{sup 12} and applied to particulate reinforced composites.

  5. 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.

  6. 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.

  7. Simplified SIMPs and the LHC

    NASA Astrophysics Data System (ADS)

    Daci, N.; De Bruyn, I.; Lowette, S.; Tytgat, M. H. G.; Zaldivar, B.

    2015-11-01

    The existence of Dark Matter (DM) in the form of Strongly Interacting Massive Particles (SIMPs) may be motivated by astrophysical observations that challenge the classical Cold DM scenario. Other observations greatly constrain, but do not completely exclude, the SIMP alternative. The signature of SIMPs at the LHC may consist of neutral, hadron-like, trackless jets produced in pairs. We show that the absence of charged content can provide a very efficient tool to suppress dijet backgrounds at the LHC, thus enhancing the sensitivity to a potential SIMP signal. We illustrate this using a simplified SIMP model and present a detailed feasibility study based on simulations, including a dedicated detector response parametrization. We evaluate the expected sensitivity to various signal scenarios and tentatively consider the exclusion limits on the SIMP elastic cross section with nucleons.

  8. Simplified Radioimmunoassay for Diagnostic Serology

    PubMed Central

    Hutchinson, Harriet D.; Ziegler, Donald W.

    1972-01-01

    A simplified, indirect radioimmunoassay is described for Escherichia coli, vaccinia virus, and herpesvirus. The antigens were affixed to glass cover slips; thus both the primary and secondary reactions take place on the cover slips, and the unbound antiserum is easily separated from the bound antiserum by rinsing. Rabbit or human immune sera were reacted with the antigens, and the primary immune complex was quantitated by a secondary reaction with 125I-indicator globulin (anti-rabbit or anti-human). A direct relationship between the antiserum concentration and the 125I absorption was established. Variations in titers were detectable, and the titers were comparable to complement fixation titers. Homologous and heterologous reactions were distinguishable. The method affords an objective, quantitative, and qualitative evaluation of antibody, and results are reproducible. PMID:4344958

  9. 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

  10. Irradiation creep relaxation of void swelling-driven stresses

    NASA Astrophysics Data System (ADS)

    Hall, M. M.

    2013-01-01

    Swelling-driven-creep test specimens are used to measure the compressive stresses that develop due to constraint of irradiation void swelling. These specimens use a previously non-irradiated 20% CW Type 316 stainless steel holder to axially restrain two Type 304 stainless steel tubular specimens that were previously irradiated in the US Experimental Breeder Reactor (EBR-II) at 490 °C. One specimen was previously irradiated to fluence levels in the void nucleation regime (9 dpa) and the other in the quasi-steady void growth regime (28 dpa). A lift-off compliance measurement technique was used post-irradiation to determine compressive stresses developed during reirradiation of the two specimen assemblies in Row 7 of EBR-II at temperatures of 547 °C and 504 °C, respectively, to additional damage levels each of about 5 dpa. Results obtained on the higher fluence swelling-driven-creep specimen show that compressive stress due to constraint of swelling retards void swelling to a degree that is consistent with active load uniaxial compression specimens that were irradiated as part of a previously reported multiaxial in-reactor creep experiment. Swelling results obtained on the lower fluence swelling-driven creep specimen show a much larger effect of compressive stress in reducing swelling, demonstrating that the larger effect of stress on swelling is on void nucleation as compared to void growth. Test results are analyzed using a recently proposed multiaxial creep-swelling model.

  11. 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.

  12. 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.

  13. 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...

  14. 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...

  15. 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...

  16. 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.

  17. Automated air-void system characterization of hardened concrete: Helping computers to count air-voids like people count air-voids---Methods for flatbed scanner calibration

    NASA Astrophysics Data System (ADS)

    Peterson, Karl

    Since the discovery in the late 1930s that air entrainment can improve the durability of concrete, it has been important for people to know the quantity, spacial distribution, and size distribution of the air-voids in their concrete mixes in order to ensure a durable final product. The task of air-void system characterization has fallen on the microscopist, who, according to a standard test method laid forth by the American Society of Testing and Materials, must meticulously count or measure about a thousand air-voids per sample as exposed on a cut and polished cross-section of concrete. The equipment used to perform this task has traditionally included a stereomicroscope, a mechanical stage, and a tally counter. Over the past 30 years, with the availability of computers and digital imaging, automated methods have been introduced to perform the same task, but using the same basic equipment. The method described here replaces the microscope and mechanical stage with an ordinary flatbed desktop scanner, and replaces the microscopist and tally counter with a personal computer; two pieces of equipment much more readily available than a microscope with a mechanical stage, and certainly easier to find than a person willing to sit for extended periods of time counting air-voids. Most laboratories that perform air-void system characterization typically have cabinets full of prepared samples with corresponding results from manual operators. Proponents of automated methods often take advantage of this fact by analyzing the same samples and comparing the results. A similar iterative approach is described here where scanned images collected from a significant number of samples are analyzed, the results compared to those of the manual operator, and the settings optimized to best approximate the results of the manual operator. The results of this calibration procedure are compared to an alternative calibration procedure based on the more rigorous digital image accuracy

  18. Macroscopic shock plasticity of brittle material through designed void patterns

    NASA Astrophysics Data System (ADS)

    Jiang, Tailong; Yu, Yin; He, Hongliang; Li, Yongqiang; Huan, Qiang; Wu, Jiankui

    2016-03-01

    The rapid propagation and coalescence of cracks and catastrophic fractures, which occur often under shock compression, compromise a brittle material's design function and restrict its scope of practical application. The shock plasticity of brittle materials can be improved significantly by introducing and designing its microstructure, which can help reduce or delay failure. We used a lattice-spring model, which can describe elastic deformation and brittle fracture of modeled material accurately, to study the influence of void distributions (random, square, hexagonal, and triangular void patterns) on the macroscopic shock response and the mesoscopic deformation feature of brittle materials. Calculated results indicate that the void patterns dominate two inelastic deformation stages on the Hugoniot stress-strain curves (the collapse deformation stage and the slippage deformation stage). It shows that the strain localization is not strong and that the broken media are closer to a round bulk when the samples exist in random and triangular void patterns. This favors an increase in deformation during the slippage deformation stage. For the samples with square and hexagonal void patterns, the strain localization is strong and the broken media are closer to columnar bulks, which favors an increase in deformation during the collapse deformation stage.

  19. 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.

  20. On the origin of the voids in the galaxy distribution

    NASA Astrophysics Data System (ADS)

    Hoffman, Y.; Shaham, J.

    1982-11-01

    The distribution of galaxies on scales larger than approximately 10 Mpc/h seems to be characterized by large voids, (20-40) Mpc/h in diameter and of amplitude delta approximately -(0.7-0.8). It was previously argued that the mere existence of such voids poses a severe problem to all dissipationless clustering theories. Here it is shown that the voids may, in fact, be a natural outcome of a dissipationless clustering scenario if both adiabatic and isothermal density perturbations exist primordially. When the nonlinear evolution of spherical voids of this type is followed for adiabatic perturbations with an index n greater than -1, it is seen that they become surrounded by a shell of positive density contrast. Their structure is insensitive to Omega 0 while their dynamics is quite sensitive to it. The maximum peculiar velocity (relative to Hubble flow) within the void is found to be: v(p)/v(H) approximately (0.4-0.5) for Omega 0 = 1.0, approximately (0.2-0.25) for Omega 0 = 0.45, and approximately equal to or less than 0.09 for Omega 0 = 0.1.

  1. Magnetic pattern at supergranulation scale: the void size distribution

    NASA Astrophysics Data System (ADS)

    Berrilli, F.; Scardigli, S.; Del Moro, D.

    2014-08-01

    The large-scale magnetic pattern observed in the photosphere of the quiet Sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large-scale cells of overturning plasma and exhibits "voids" in magnetic organization. These voids include internetwork fields, which are mixed-polarity sparse magnetic fields that populate the inner part of network cells. To single out voids and to quantify their intrinsic pattern we applied a fast circle-packing-based algorithm to 511 SOHO/MDI high-resolution magnetograms acquired during the unusually long solar activity minimum between cycles 23 and 24. The computed void distribution function shows a quasi-exponential decay behavior in the range 10-60 Mm. The lack of distinct flow scales in this range corroborates the hypothesis of multi-scale motion flows at the solar surface. In addition to the quasi-exponential decay, we have found that the voids depart from a simple exponential decay at about 35 Mm.

  2. Surveying for Dwarf Galaxies Within Void FN8

    NASA Astrophysics Data System (ADS)

    McNeil, Stephen R.

    2016-06-01

    The dwarf galaxy population in low density volumes, or voids, is a test of galaxy formation models and how they treat dark matter; some models say dwarf galaxies cannot be in void centers while others say they can. Since it appears many dwarf galaxies are H-alpha emitters, a well-designed deep survey through a nearby void center will either find nothing, and thus constrain the population there to be at some percentage below the mean, or it will find H-alpha emitters and significantly challenge several otherwise successful theories. Either result is a significant step in better understanding galaxy formation and large-scale structure. In 2013, a redshifted H-alpha imaging survey was begun for dwarf galaxies with ‑14.0 ≤ Mr ≤ ‑12.0 in the heart and back of the void FN8. Our first results have been surprising, furnishing significantly more candidate objects than anticipated. Through the Gemini Fast Turnaround Program, seven spectrum have been obtained, with one spectrum being a strong candidate for habitation within the center of the void.

  3. 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.

  4. The persistent percolation of single-stream voids

    NASA Astrophysics Data System (ADS)

    Falck, B.; Neyrinck, M. C.

    2015-07-01

    We study the nature of voids defined as single-stream regions that have not undergone shell-crossing. We use ORIGAMI to determine the cosmic web morphology of each dark matter particle in a suite of cosmological N-body simulations, which explicitly calculates whether a particle has crossed paths with others along multiple sets of axes and does not depend on a parameter or smoothing scale. The theoretical picture of voids is that of expanding underdensities with borders defined by shell-crossing. We find instead that locally underdense single-stream regions are not bounded on all sides by multi-stream regions, thus they percolate, filling the simulation volume; we show that the set of multi-stream particles also percolates. This percolation persists to high resolution, where the mass fraction of single-stream voids is low, because the volume fraction remains high; we speculate on the fraction of collapsed mass in the continuum limit of infinite resolution. By introducing a volume threshold parameter to define underdense void `cores', we create a catalogue of ORIGAMI voids which consist entirely of single-stream particles and measure their percolation properties, volume functions, and average densities.

  5. Discussion of Void nucleation in constrained silver interlayers'' and Void growth and coalescence in constrained silver interlayers''

    SciTech Connect

    Kassner, M.E.; Tolle, M.C. . Dept. of Mechanical Engineering); Rosen, R.S.; Henshall, G.A.; Elmer, J.W. )

    1993-08-01

    The authors have read with some concern the two articles by Klassen, Weatherly, and Ramaswami (KWR) entitled Void Nucleation in Constrained Silver Interlayers'' and Void Growth and Coalescence in Constrained Silver Interlayers'' published recently in this journal. They have several comments to these articles. First, substantial portions of these articles appear to closely reaffirm experiments and stress analyses on fracture and other mechanical behavior of constrained silver interlayers already published. KWR appeared to be unaware of (or disregarded) much of these works and this communication is partly intended to direct KWR and perhaps others to these works. Next, although there are many scientific aspects of the articles that warrant discussion, they have focused on two principal points. First, there appear to be some odd aspects of the Nucleation (KWR) article. The authors suggest nucleation and unstable growth occur only near the fracture stress (S[sub f]). This clearly is in contradiction to their careful work, where nucleation is shown to occur at very low stress (S[sub f]/5), just above the uniaxial yield stress of the interlayer silver. Second, and more importantly, KWR do not report any void growth. This, also, is in contradiction to earlier work on void growth in constrained silver interlayers. In the case of brazed silver joints, the shrinkage voids are observed to grow until a critical void separation is reached and instability occurs. In their work, voids appear to grow from small to larger cavities with small overall plastic strain in the interlayer, including at the base-metal/silver interface. In summary, although the KWR articles reasonably reproduced some established experimental trends for constrained interlayers and observed some other phenomena particularly relevant to the case with a substantial volume fraction of dispersions, other more basic conclusions relating to final fracture do not appear to consider more reasonable approaches.

  6. 48 CFR 453.213 - Simplified Acquisition and other simplified purchase procedures (AD-838).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... other simplified purchase procedures (AD-838). 453.213 Section 453.213 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE CLAUSES AND FORMS FORMS Prescription of Forms 453.213 Simplified Acquisition and other simplified purchase procedures (AD-838). Form AD-838, Purchase Order, is prescribed...

  7. 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.

  8. 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.

  9. Voronoi and void statistics for superhomogeneous point processes.

    PubMed

    Gabrielli, Andrea; Torquato, Salvatore

    2004-10-01

    We study the Voronoi and void statistics of superhomogeneous (or hyperuniform) point patterns in which the infinite-wavelength density fluctuations vanish. Superhomogeneous or hyperuniform point patterns arise in one-component plasmas, primordial density fluctuations in the Universe, and jammed hard-particle packings. We specifically analyze a certain one-dimensional model by studying size fluctuations and correlations of the associated Voronoi cells. We derive exact results for the complete joint statistics of the size of two Voronoi cells. We also provide a sum rule that the correlation matrix for the Voronoi cells must obey in any space dimension. In contrast to the conventional picture of superhomogeneous systems, we show that infinitely large Voronoi cells or voids can exist in superhomogeneous point processes in any dimension. We also present two heuristic conditions to identify and classify any superhomogeneous point process in terms of the asymptotic behavior of the void size distribution. PMID:15600395

  10. 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.

  11. 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.

  12. Only the Lonely: H I Imaging of Void Galaxies

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

    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 × 108 to 3.8 × 109 M sun, with one nondetection with an upper limit of 2.1 × 108 M 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.

  13. 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.

  14. Three-dimensional micromechanical modeling of voided polymeric materials

    NASA Astrophysics Data System (ADS)

    Danielsson, M.; Parks, D. M.; Boyce, M. C.

    2002-02-01

    A three-dimensional micromechanical unit cell model for particle-filled materials is presented. The cell model is based on a Voronoi tessellation of particles arranged on a body-centered cubic (BCC) array. The three-dimensionality of the present cell model enables the study of several deformation modes, including uniaxial, plane strain and simple shear deformations, as well as arbitrary principal stress states. The unit cell model is applied to studies on the micromechanical and macromechanical behavior of rubber-toughened polycarbonate. Different load cases are examined, including plane strain deformation, simple shear deformation and principal stress states. For a constant macroscopic strain rate, the different load cases show that the macroscopic flow strength of the blend decreases with an increase in void volume fraction, as expected. The main mechanism for plastic deformation is broad shear banding across inter-particle ligaments. The distributed nature of plastic straining acts to reduce the amount of macroscopic strain softening in the blend as the initial void volume fraction is increased. In the case of plane strain deformation, the plastic flow is observed to initiate across inter-particle ligaments in the direction of constraint. This particular mode of deformation could not have been captured using a two-dimensional, plane strain idealization of cylindrical voids in a matrix. The potential for localized crazing and/or cavitation in the matrix is addressed. It is observed that the introduction of voids acts to relieve hydrostatic stress in the matrix material, compared to the homopolymer. It is also seen that the predicted peak hydrostatic stress in the matrix is higher under plane strain deformation than under triaxial tension (with equal lateral stresses), for the same macroscopic stress triaxiality. The effect of void volume fraction on the macroscopic uniaxial tension behavior of the different blends is examined using a Considère construction for

  15. 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

  16. 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

  17. Evaluation and management of voiding dysfunction after midurethral sling procedures

    PubMed Central

    Çelik, Hatice; Harmanlı, Özgür

    2012-01-01

    Midurethral slings have become the most popular surgical procedure for the correction of stress urinary incontinence in women. Urinary retention or obstructive voiding symptoms may arise from partial urethral obstruction as a result of oversuspension of the urethra or exaggerated tension. Fortunately, most cases of voiding dysfunction are transient and resolve spontaneously within days. Clean intermittent self-catheterization is the mainstay of conservative treatment. If symptoms persist, tape mobilization, incision or urethrolysis may be performed. Recurrent stress urinary incontinence may occur in a small group of patients, who may benefit from another incontinence treatment. PMID:24592021

  18. 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.

  19. Dimensionality effects in void-induced explosive sensitivity

    DOE PAGESBeta

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

    2016-07-06

    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.

  20. Voiding Dysfunction Induced by Tetanus: A Case Report

    PubMed Central

    Kira, Satoru; Sawada, Norifumi; Aoki, Tadashi; Kobayashi, Hideki; Takeda, Masayuki

    2016-01-01

    A 34-year-old man presented with sudden voiding dysfunction and lower limb paraplegia. As a central nervous system disorder was suspected, he was referred to the neurology department. Under the diagnosis of neurosarcoidosis, steroid pulse therapy was initiated. To ensure the effect of this therapy, the patient was referred back for urodynamic testing. Urodynamic testing indicated that the urethral sphincter was not relaxed and could not void. Due to the sudden appearance of repeated and refractory opisthotonus, tetanus was strongly suspected. After administration of antibiotics and tetanus immune globulin, those symptoms disappeared. PMID:26793588

  1. Voids within the two-component dust model

    NASA Astrophysics Data System (ADS)

    Haager, Gernot

    1998-11-01

    A new family within the spherically symmetric two-component dust metrics (Haager G 1997 Class. Quantum Grav. 14 2219) with an additional homothetic vector is investigated in detail. These metrics are regular except for a big bang singularity and can be given by an asymptotic expansion of the metric coefficients for large times after the big bang. Using this family, voids can be described whose edge is not comoving in comparison with its surroundings. A concrete example is given where the edge of the void is contracting, while the dust background is expanding.

  2. Simplified method for nonlinear structural analysis

    NASA Technical Reports Server (NTRS)

    Kaufman, A.

    1983-01-01

    A simplified inelastic analysis computer program was developed for predicting the stress-strain history of a thermomechanically cycled structure from an elastic solution. The program uses an iterative and incremental procedure to estimate the plastic strains from the material stress-strain properties and a simulated plasticity hardening model. The simplified method was exercised on a number of problems involving uniaxial and multiaxial loading, isothermal and nonisothermal conditions, and different materials and plasticity models. Good agreement was found between these analytical results and nonlinear finite element solutions for these problems. The simplified analysis program used less than 1 percent of the CPU time required for a nonlinear finite element analysis.

  3. Experimental demonstration of simplified quantum process tomography.

    PubMed

    Wu, Z; Li, S; Zheng, W; Peng, X; Feng, M

    2013-01-14

    The essential tool to characterize dynamics of an open quantum system is quantum process tomography (QPT). Although standard QPT methods are hard to be scalable, simplified QPT approach is available if we have the prior knowledge that the system Hamiltonian commutes with the system-environment interaction Hamiltonian. Using a nuclear magnetic resonance (NMR) quantum simulator, we experimentally simulate dephasing channels to demonstrate the simplified QPT as well as the standard QPT method as a comparison. The experimental results agree well with our predictions which confirm the validity and better efficiency of the simplified QPT. PMID:23320694

  4. Voiding postponement in children-a systematic review.

    PubMed

    von Gontard, Alexander; Niemczyk, Justine; Wagner, Catharina; Equit, Monika

    2016-08-01

    Voiding postponement (VP) has been defined as a habitual postponement of micturition using holding maneuvers. VP can represent both a symptom, as well as a condition. As divergent definitions are used internationally, the aim was to review the current state of knowledge on VP and provide recommendations for assessment, diagnosis and treatment. A Scopus and a Pubmed search was conducted, entering the terms 'voiding postponement' without any restrictions or specifications. Other publications relevant to the topic were added. VP can represent a symptom in healthy children. As a condition, VP in combination with nocturnal enuresis (NE) is a subtype of non-monosymptomatic NE. Most studies have focused on daytime urinary incontinence (DUI) with VP, or more aptly termed voiding postponement incontinence (VPI). It is a behaviorally defined syndrome, i.e., by the habitual deferral of micturition and DUI. VPI is associated with a low micturition frequency, urgency and behavioral problems. The most common comorbid disorder is oppositional defiant disorder (ODD). VP as a symptom and VPI as a condition should be differentiated. VPI is a common disorder with many associated problems and disorders. Urotherapy and timed voiding are the main treatment approaches. Due to the high rate of comorbid ODD, other forms of treatment, especially cognitive behavioral therapy, are often needed. PMID:26781489

  5. Low-void polyimide resins for autoclave processing

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Vaughan, R. W.

    1972-01-01

    Development of an advanced A-type polyimide, which can be used to produce autoclave molded, low-void content composites suitable for use at temperatures up to 316 C is reported. It consists of a mixture of methyl nadic anhydride, an 80:20 molar ratio of methylene dianaline and thiodianilene, and pyromellitic dianhydride.

  6. Voids in Jovian magnetosphere revisited - Evidence of spacecraft charging

    NASA Technical Reports Server (NTRS)

    Khurana, K. K.; Kivelson, M. G.; Walker, R. J.; Armstrong, T. P.

    1987-01-01

    The Voyager 2 Plasma Science Instrument (PLS) measuring cold plasma number density observed about a dozen 'voids', lasting from a few minutes to 20 min, in the vicinity of the Ganymede-orbit crossing, when the low-energy ion and electron fluxes recorded fell to very low levels. Original interpretations associated these 'voids' with Ganymede wake effects. In the present study, the PLS data are reexamined, in conjunction with data from the magnetic field experiment and the low-energy charged particle (LECP) experiment. The LECP data showed that the PLS voids were accompanied by large enhancements of the flux of energetic electrons and ions, while the magnetic data exhibited no systematic signatures. It is suggested that increased energetic electron fluxes in the void regions intermittently charged the spacecraft negatively to values between a few kV and a few tens of kV, and that spacecraft charging could have produce dropouts in the measured cold ion and electron fluxes and enhancements in the measured fluxes of hot particles consistent with the observations.

  7. Kinetic Monte Carlo Simulations of Void Lattice Formation During Irradiation

    SciTech Connect

    Heinisch, Howard L.; Singh, Bachu N.

    2003-12-01

    Within the last decade molecular dynamics simulations of displacement cascades have revealed that glissile clusters of self-interstitial crowdions are formed directly in cascades and that they migrate one-dimensionally along close-packed directions with extremely low activation energies. Occasionally, under various conditions, a crowdion cluster can change its Burgers vector and glide along a different close-packed direction. The recently developed Production Bias Model (PBM) of microstructure evolution under irradiation has been structured to specifically take into account the unique properties of the vacancy and interstitial clusters produced in the cascades. Atomic-scale kinetic Monte Carlo (KMC) simulations have played a useful role in understanding the defect reaction kinetics of one-dimensionally migrating crowdion clusters as a function of the frequency of direction changes. This has made it possible to incorporate the migration properties of crowdion clusters and changes in reaction kinetics into the PBM. In the present paper we utilize similar KMC simulations to investigate the significant role crowdion clusters can play in the formation and stability of void lattices. The creation of stable void lattices, starting from a random distribution of voids, is simulated by a KMC model in which vacancies migrate three-dimensionally and SIA clusters migrate one-dimensionally, interrupted by directional changes. The necessity of both one-dimensional migration and Burgers vectors changes of SIA clusters for the production of stable void lattices is demonstrated, and the effects of the frequency of Burgers vector changes are described.

  8. 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.

  9. 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.

  10. 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.

  11. 3D optical tomography in the presence of void regions

    NASA Astrophysics Data System (ADS)

    Riley, J.; Dehghani, Hamid; Schweiger, Martin; Arridge, Simon R.; Ripoll, Jorge; Nieto-Vesperinas, Manuel

    2000-12-01

    We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example.

  12. 3D optical tomography in the presence of void regions.

    PubMed

    Riley, J; Dehghani, H; Schweiger, M; Arridge, S; Ripoll, J; Nieto-Vesperinas, M

    2000-12-18

    We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example. PMID:19407898

  13. 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. PMID:27610841

  14. 3. 6 simplified methods for design

    SciTech Connect

    Nickell, R.E.; Yahr, G.T.

    1981-01-01

    Simplified design analysis methods for elevated temperature construction are classified and reviewed. Because the major impetus for developing elevated temperature design methodology during the past ten years has been the LMFBR program, considerable emphasis is placed upon results from this source. The operating characteristics of the LMFBR are such that cycles of severe transient thermal stresses can be interspersed with normal elevated temperature operational periods of significant duration, leading to a combination of plastic and creep deformation. The various simplified methods are organized into two general categories, depending upon whether it is the material, or constitutive, model that is reduced, or the geometric modeling that is simplified. Because the elastic representation of material behavior is so prevalent, an entire section is devoted to elastic analysis methods. Finally, the validation of the simplified procedures is discussed.

  15. Three-Dimensional Molecular Dynamics Simulations of Void Coalescence during Dynamic Fracture of Ductile Metals

    SciTech Connect

    Seppala, E T; Belak, J; Rudd, R E

    2004-09-02

    Void coalescence and interaction in dynamic fracture of ductile metals have been investigated using three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. The interaction of the voids is not reflected in the volumetric asymptotic growth rate of the voids, as demonstrated here. Finally, the practice of using a single void and periodic boundary conditions to study coalescence is examined critically and shown to produce results markedly different than the coalescence of a pair of isolated voids.

  16. 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.

  17. Simplified models for LHC new physics searches

    NASA Astrophysics Data System (ADS)

    Alves, Daniele; Arkani-Hamed, Nima; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua; Buckley, Matthew; Butler, Bart; Chang, Spencer; Cheng, Hsin-Chia; Cheung, Clifford; Sekhar Chivukula, R.; Cho, Won Sang; Cotta, Randy; D'Alfonso, Mariarosaria; El Hedri, Sonia; Essig (Editor, Rouven; Evans, Jared A.; Fitzpatrick, Liam; Fox, Patrick; Franceschini, Roberto; Freitas, Ayres; Gainer, James S.; Gershtein, Yuri; Gray, Richard; Gregoire, Thomas; Gripaios, Ben; Gunion, Jack; Han, Tao; Haas, Andy; Hansson, Per; Hewett, JoAnne; Hits, Dmitry; Hubisz, Jay; Izaguirre, Eder; Kaplan, Jared; Katz, Emanuel; Kilic, Can; Kim, Hyung-Do; Kitano, Ryuichiro; Koay, Sue Ann; Ko, Pyungwon; Krohn, David; Kuflik, Eric; Lewis, Ian; Lisanti (Editor, Mariangela; Liu, Tao; Liu, Zhen; Lu, Ran; Luty, Markus; Meade, Patrick; Morrissey, David; Mrenna, Stephen; Nojiri, Mihoko; Okui, Takemichi; Padhi, Sanjay; Papucci, Michele; Park, Michael; Park, Myeonghun; Perelstein, Maxim; Peskin, Michael; Phalen, Daniel; Rehermann, Keith; Rentala, Vikram; Roy, Tuhin; Ruderman, Joshua T.; Sanz, Veronica; Schmaltz, Martin; Schnetzer, Stephen; Schuster (Editor, Philip; Schwaller, Pedro; Schwartz, Matthew D.; Schwartzman, Ariel; Shao, Jing; Shelton, Jessie; Shih, David; Shu, Jing; Silverstein, Daniel; Simmons, Elizabeth; Somalwar, Sunil; Spannowsky, Michael; Spethmann, Christian; Strassler, Matthew; Su, Shufang; Tait (Editor, Tim; Thomas, Brooks; Thomas, Scott; Toro (Editor, Natalia; Volansky, Tomer; Wacker (Editor, Jay; Waltenberger, Wolfgang; Yavin, Itay; Yu, Felix; Zhao, Yue; Zurek, Kathryn; LHC New Physics Working Group

    2012-10-01

    This document proposes a collection of simplified models relevant to the design of new-physics searches at the Large Hadron Collider (LHC) and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the ‘Topologies for Early LHC Searches’ workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ˜50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.

  18. Simplified Models for LHC New Physics Searches

    SciTech Connect

    Alves, Daniele; Arkani-Hamed, Nima; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua; Buckley, Matthew; Butler, Bart; Chang, Spencer; Cheng, Hsin-Chia; Cheung, Clifford; Chivukula, R.Sekhar; Cho, Won Sang; Cotta, Randy; D'Alfonso, Mariarosaria; El Hedri, Sonia; Essig, Rouven,; Evans, Jared A.; Fitzpatrick, Liam; Fox, Patrick; Franceschini, Roberto; /more authors..

    2012-06-01

    This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the 'Topologies for Early LHC Searches' workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first {approx} 50-500 pb{sup -1} of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.

  19. Molecular dynamics simulations of void coalescence in monocrystalline copper under loading and unloading

    NASA Astrophysics Data System (ADS)

    Peng, Xiaojuan; Zhu, Wenjun; Chen, Kaiguo; Deng, Xiaoliang; Wei, Yongkai

    2016-04-01

    Molecular dynamic calculations are used to examine the anisotropy of voids coalescence under loading and unloading conditions in monocrystalline coppers. In this paper, three typical orientations are investigated, including [100], [110], and [111]. The study shows that voids collapse after the shock loading, leaving two disordered regions at the initial voids sites. Voids re-nucleate in the disordered regions and grow by the emission of dislocations on various slip planes. The dislocation motion contributes to local stress relaxation, which causes the voids to expand to certain radius and then coalesce with each other by dislocation emission. Due to the influence of the anisotropy shear field and different slip systems around the voids, the dislocations emit more easily at specific position, which lead to the anisotropy of void coalescence. A two-dimensional analysis model based on a shear dislocation is proposed and it explains the phenomena of void coalescence in the simulations quite well.

  20. Hypobaric Conditions Within Rock Void Spaces on Mars will Likely Inhibit the Replication of Terrestrial Microorganisms

    NASA Astrophysics Data System (ADS)

    Schuerger, A. C.; Britt, D.

    2011-03-01

    Internal void spaces within rocks outgas rapidly under simulated martian conditions. Water activity and pressure within rock void spaces are not sufficient to permit the replication of terrestrial microorganisms from spacecraft on Mars.

  1. 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,...

  2. 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.

  3. 42 CFR 457.216 - Treatment of uncashed or canceled (voided) CHIP checks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Treatment of uncashed or canceled (voided) CHIP... canceled (voided) CHIP checks. (a) Purpose. This section provides rules to ensure that States refund the... section— Canceled (voided) check means an CHIP check issued by a State or fiscal agent that prior to...

  4. 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,...

  5. 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,...

  6. 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,...

  7. 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,...

  8. Advanced modeling of electron avalanche process in polymeric dielectric voids: Simulations and experimental validation

    NASA Astrophysics Data System (ADS)

    Testa, L.; Serra, S.; Montanari, G. C.

    2010-08-01

    This paper deals with aging phenomena in polymers under electric stress. In particular, we focus our efforts on the development of a novel theoretical method accounting for the discharge process (partial discharge) in well known defects present in polymers, which are essentially tiny air gaps embedded in a polymeric matrix. Such defects are believed to act as trigger points for the partial discharges and their induced aging process. The model accounts for the amplitude as well as the energy distribution of the electrons during their motion, particularly at the time in which they impact on the polymer surface. The knowledge of the number of generated electrons and of their energy distributions is fundamental to evaluate the amount of damage caused by an avalanche on the polymer-void interface and get novel insights of the basic phenomena underlying the relevant aging processes. The calculation of such quantities would require generally the combined solution of the Boltzmann equation in the energy and space/time domains. The proposed method simplifies the problem, taking into account only the main phenomena involved in the process and provides a partial discharge (PD) model virtually free of adjustable parameters. This model is validated by an accurate experimental procedure aimed at reproducing the same conditions of the simulations and regarding air gaps embedded in polymeric dielectrics. The experimental results confirm the validity and accuracy of the proposed approach.

  9. Shock wave induced damage of a protein by void collapse

    DOE PAGESBeta

    Lau, Edmond Y.; Berkowitz, Max L.; Schwegler, Eric R.

    2016-01-05

    In this study, we report on a series of molecular dynamics simulations that were used to examine the effects of shockwaves on a membrane bound ion channel. A planar shockwave was found to compress the ion channel upon impact but the protein geometry resembles the initial structure as soon as the solvent density begins to dissipate. When a void was placed in close proximity to the membrane, the shockwave proved to be much more destructive to the protein due to formation of a nanojet that results from the asymmetric collapse of the void. The nanojet was able to cause significantmore » structural changes to the protein even at low particle velocities that are not able to directly cause poration of the membrane.« less

  10. On the void explanation of the Cold Spot

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  11. 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.

  12. Anterior vaginal wall prolapse and voiding dysfunction in urogynecology patients.

    PubMed

    Schimpf, Megan O; O'Sullivan, David M; LaSala, Christine A; Tulikangas, Paul K

    2007-07-01

    We investigated whether women with and without anterior vaginal wall prolapse have voiding differences. Women (n=109) who presented to a urogynecology practice were categorized into two groups based on anterior vaginal wall prolapse: stages 0 and 1 and stages 2, 3, and 4. Women with prolapse were older than the women without prolapse but the groups were otherwise similar demographically. There was a higher rate of activity-related urine loss and use of wetness protection amongst women without prolapse. There was no significant difference for urgency symptoms or urge incontinence. Urodynamic testing found no significant differences for maximal flow rate or maximal urethral closing pressures. Postvoid residual volume and detrusor overactivity were not different but approached significance. Anterior vaginal wall prolapse of stage 2 or greater was not associated with urge incontinence or voiding function in this population. Women without prolapse were more likely to report stress incontinence. PMID:17031486

  13. 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)

  14. A halo bias function measured deeply into voids without stochasticity

    NASA Astrophysics Data System (ADS)

    Neyrinck, Mark C.; Aragón-Calvo, Miguel A.; Jeong, Donghui; Wang, Xin

    2014-06-01

    We study the relationship between dark-matter haloes and matter in the MIP (multum in parvo) N-body simulation ensemble, which allows precision measurements of this relationship, even deeply into voids. What enables this is a lack of discreteness, stochasticity, and exclusion, achieved by averaging over hundreds of possible sets of initial small-scale modes, while holding fixed large-scale modes that give the cosmic web. We find (i) that dark-matter-halo formation is greatly suppressed in voids; there is an exponential downturn at low densities in the otherwise power-law matter-to-halo density bias function. Thus, the rarity of haloes in voids is akin to the rarity of the largest clusters, and their abundance is quite sensitive to cosmological parameters. The exponential downturn appears both in an excursion-set model, and in a model in which fluctuations evolve in voids as in an open universe with an effective Ωm proportional to a large-scale density. We also find that (ii) haloes typically populate the average halo-density field in a super-Poisson way, i.e. with a variance exceeding the mean; and (iii) the rank-order-Gaussianized halo and dark-matter fields are impressively similar in Fourier space. We compare both their power spectra and cross-correlation, supporting the conclusion that one is roughly a strictly increasing mapping of the other. The MIP ensemble especially reveals how halo abundance varies with `environmental' quantities beyond the local matter density; (iv) we find a visual suggestion that at fixed matter density, filaments are more populated by haloes than clusters.

  15. The Dynamic Response of Energetic Formulations to Embedded Voids.

    NASA Astrophysics Data System (ADS)

    Glenn, Gregg; Yasuyuki, Horie; Gunger, Michael

    2007-06-01

    Programs are underway at AFRL and other labs to investigate the phenomenology of the response of energetic materials to long duration (>1 ms) loading environments. As part of these efforts, the effect of a defect, primarily in the form of a void, is the focus of the investigation. This paper will present a combined test and analytical study of multiple composite energetic formulations and will include a significant amount of test data. The primary variables associated with the loading environment are pressure, duration and loading rate. The energetic formulations primarily consist of ammonium perchlorate (AP), RDX, aluminum flake and HTPB binder. Void size and peak pressure were varied to determine safe loading margins. Post-test observations of reacted material were performed using a scanning electron microscope (SEM) to determine damage, crystal response and reaction locations within the sample. X-ray analysis was performed on unreacted samples to compare with reacted samples. The results are providing critical information on the sensitivity of an explosive formulation to void compression as a function of formulation, loading rate, peak pressure and duration. The results of these tests can be used in simulations to develop an improved understanding of mechanical and thermal initiation of energetic materials.

  16. 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.

  17. 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.

  18. 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.

  19. Nebular metallicities in two isolated local void dwarf galaxies

    SciTech Connect

    Nicholls, David C.; Jerjen, Helmut; Dopita, Michael A.; Basurah, Hassan

    2014-01-01

    Isolated dwarf galaxies, especially those situated in voids, may provide insight into primordial conditions in the universe and the physical processes that govern star formation in undisturbed stellar systems. The metallicity of H II regions in such galaxies is key to investigating this possibility. From the SIGRID sample of isolated dwarf galaxies, we have identified two exceptionally isolated objects, the Local Void galaxy [KK98]246 (ESO 461-G036) and another somewhat larger dwarf irregular on the edge of the Local Void, MCG-01-41-006 (HIPASS J1609-04). We report our measurements of the nebular metallicities in these objects. The first object has a single low luminosity H II region, while the second is in a more vigorous star forming phase with several bright H II regions. We find that the metallicities in both galaxies are typical for galaxies of this size, and do not indicate the presence of any primordial gas, despite (for [KK98]246) the known surrounding large reservoir of neutral hydrogen.

  20. Λ effect in the cosmological expansion of void

    SciTech Connect

    Fliche, Henri-Hugues; Triay, Roland E-mail: triay@cpt.univ-mrs.fr

    2010-11-01

    We investigate the dynamical effect of the cosmological constant Λ on a single spherical vacuum void evolving in the universe within a global solution of Newton-Friedmann models. As a result, the main characteristic is that the void expands with a huge initial burst up to match asymptotically the Hubble flow. The size of voids increases with Ω{sub o} and with Λ, which is interpreted as respectively by the gravitational attraction of borders from outside regions and by the gravitational repulsion of vacuum from the inner region. The Λ-effect on the kinematics intervenes significantly by amplifying the expansion rate at redshift z ∼ 1.7 for a background density parameter Ω{sub o} ∼ 0.3. For a class of parameters values, which corresponds in GR to spatially closed Friedmann models, it is interesting to note that a test particle in the inner region moves toward the border. Such a peculiar feature shows that the empty regions are swept out; which stands as a stability criterion.

  1. Void-containing materials with tailored Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Goussev, Olga A.; Richner, Peter; Rozman, Michael G.; Gusev, Andrei A.

    2000-10-01

    Assuming square, hexagonal, and random packed arrays of nonoverlapping identical parallel cylindrical voids dispersed in an aluminum matrix, we have calculated numerically the concentration dependence of the transverse Poisson's ratios. It was shown that the transverse Poisson's ratio of the hexagonal and random packed arrays approached 1 upon increasing the concentration of voids while the ratio of the square packed array along the principal continuation directions approached 0. Experimental measurements were carried out on rectangular aluminum bricks with identical cylindrical holes drilled in square and hexagonal packed arrays. Experimental results were in good agreement with numerical predictions. We then demonstrated, based on the numerical and experimental results, that by varying the spatial arrangement of the holes and their volume fraction, one can design and manufacture voided materials with a tailored Poisson's ratio between 0 and 1. In practice, those with a high Poisson's ratio, i.e., close to 1, can be used to amplify the lateral responses of the structures while those with a low one, i.e., close to 0, can largely attenuate the lateral responses and can therefore be used in situations where stringent lateral stability is needed.

  2. 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.

  3. Development of long operating cycle simplified BWR

    SciTech Connect

    Heki, H.; Nakamaru, M.; Maruya, T.; Hiraiwa, K.; Arai, K.; Narabayash, T.; Aritomi, M.

    2002-07-01

    This paper describes an innovative plant concept for long operating cycle simplified BWR (LSBWR) In this plant concept, 1) Long operating cycle ( 3 to 15 years), 2) Simplified systems and building, 3) Factory fabrication in module are discussed. Designing long operating core is based on medium enriched U-235 with burnable poison. Simplified systems and building are realized by using natural circulation with bottom located core, internal CRD and PCV with passive system and an integrated reactor and turbine building. This LSBWR concept will have make high degree of safety by IVR (In Vessel Retention) capability, large water inventory above the core region and no PCV vent to the environment due to PCCS (Passive Containment Cooling System) and internal vent tank. Integrated building concept could realize highly modular arrangement in hull structure (ship frame structure), ease of seismic isolation capability and high applicability of standardization and factory fabrication. (authors)

  4. Simplified models for exotic BSM searches

    NASA Astrophysics Data System (ADS)

    Heisig, Jan; Lessa, Andre; Quertenmont, Loic

    2015-12-01

    Simplified models are a successful way of interpreting current LHC searches for models beyond the standard model (BSM). So far simplified models have focused on topologies featuring a missing transverse energy (MET) signature. However, in some BSM theories other, more exotic, signatures occur. If a charged particle becomes long-lived on collider time scales — as it is the case in parts of the SUSY parameter space — it leads to a very distinct signature. We present an extension of the computer package SModelS which includes simplified models for heavy stable charged particles (HSCP). As a physical application we investigate the CMSSM stau co-annihilation strip containing long-lived staus, which presents a potential solution to the Lithium problem. Applying both MET and HSCP constraints we show that, for low values of tan β, all this region of parameter space either violates Dark Matter constraints or is excluded by LHC searches.

  5. Hypersonic Vehicle Propulsion System Simplified Model Development

    NASA Technical Reports Server (NTRS)

    Stueber, Thomas J.; Raitano, Paul; Le, Dzu K.; Ouzts, Peter

    2007-01-01

    This document addresses the modeling task plan for the hypersonic GN&C GRC team members. The overall propulsion system modeling task plan is a multi-step process and the task plan identified in this document addresses the first steps (short term modeling goals). The procedures and tools produced from this effort will be useful for creating simplified dynamic models applicable to a hypersonic vehicle propulsion system. The document continues with the GRC short term modeling goal. Next, a general description of the desired simplified model is presented along with simulations that are available to varying degrees. The simulations may be available in electronic form (FORTRAN, CFD, MatLab,...) or in paper form in published documents. Finally, roadmaps outlining possible avenues towards realizing simplified model are presented.

  6. 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

  7. A simplified model for glass formation

    NASA Technical Reports Server (NTRS)

    Uhlmann, D. R.; Onorato, P. I. K.; Scherer, G. W.

    1979-01-01

    A simplified model of glass formation based on the formal theory of transformation kinetics is presented, which describes the critical cooling rates implied by the occurrence of glassy or partly crystalline bodies. In addition, an approach based on the nose of the time-temperature-transformation (TTT) curve as an extremum in temperature and time has provided a relatively simple relation between the activation energy for viscous flow in the undercooled region and the temperature of the nose of the TTT curve. Using this relation together with the simplified model, it now seems possible to predict cooling rates using only the liquidus temperature, glass transition temperature, and heat of fusion.

  8. Heavy Flavor Simplified Models at the LHC

    SciTech Connect

    Essig, Rouven; Izaguirre, Eder; Kaplan, Jared; Wacker, Jay G.; /SLAC

    2012-04-03

    We consider a comprehensive set of simplified models that contribute to final states with top and bottom quarks at the LHC. These simplified models are used to create minimal search strategies that ensure optimal coverage of new heavy flavor physics involving the pair production of color octets and triplets. We provide a set of benchmarks that are representative of model space, which can be used by experimentalists to perform their own optimization of search strategies. For data sets larger than 1 fb{sup -1}, same-sign dilepton and 3b search regions become very powerful. Expected sensitivities from existing and optimized searches are given.

  9. 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.

  10. 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.