WorldWideScience

Sample records for non-extendably collapsible 3-ball

  1. Quantum vacuum effects on the final fate of a collapsing ball of dust

    Energy Technology Data Exchange (ETDEWEB)

    Arfaei, Hessamaddin [Department of Physics, Sharif University of Technology,P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences(IPM),P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Noorikuhani, Milad [Department of Physics, Sharif University of Technology,P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of)

    2017-02-24

    We consider the quantum vacuum effects of the massless scalar fields that are non-minimally coupled to the background geometry of a collapsing homogeneous ball of dust. It is shown that for a definite range of coupling constants, there are repulsive quantum vacuum effects, capable of stopping the collapse process inside the black hole and precluding the formation of singularity. The final fate of the collapse will be a black hole with no singularity, inside which the matter stays balanced. The density of the final static matter will be close to the Planck density. We show that the largest possible radius of the stable static ball inside a black hole with Schwarzschild mass M is given by ((1/(90π))(M/(m{sub p}))){sup (1/3)}ℓ{sub p}. If the black hole undergoes Hawking radiation, the final state will be an extremal quantum-corrected black hole, with zero temperature, with a remnant of matter inside. We show that the resolution of singularity is not disrupted under Hawking radiation.

  2. Anti-collapse mechanism of CBM fuzzy-ball drilling fluid

    Directory of Open Access Journals (Sweden)

    Lihui Zheng

    2016-03-01

    Full Text Available Although fuzzy-ball drilling fluid has been successfully applied in CBM well drilling, it is necessary to study its anti-collapse mechanism so that adjustable coalbed sealing effects, controllable sealing strength, rational sealing cost and controllable reservoir damage degree can be realized. In this paper, laboratory measurement was performed on the uniaxial compressive strength of the plungers of No. 3 coalbed in the Qinshui Basin and the inlet pressure of Ø38 mm coal plunger displacement. The strengths of coal plungers were tested and compared after 2% potassium chloride solution, low-solids polymer drilling fluid and fuzzy-ball drilling fluid were injected into the coal plungers respectively. It is shown that coal strength rises by 38.46% after the fuzzy-ball drilling fluid is injected (in three groups; and that no fuzzy-ball drilling fluid is lost at the displacement pressures of 20.73 and 21.46 MPa, nor 2% potassium chloride solution is leaked at such pressures of 24.79 and 25.64 MPa after the plunger was sealed by the fuzzy-ball drilling fluid. This indicates that the fuzzy-ball drilling fluid can increase the formation resistance to fluid. Indoor microscopic observation was conducted on the sealing process of the fuzzy-ball drilling fluid in sand packs with coal cuttings of three grain sizes (60–80, 80–100 and 100–120 mesh. It is shown that the leakage pathways of different sizes are sealed by the vesicles in the form of accumulation, stretch and blockage. And there are vesicles at the inlet ends of the flowing pathways in the shape of beaded blanket. The impact force of drilling tools on the sidewalls is absorbed by the vesicles due to their elasticity and tenacity, so the sidewall instability caused by drilling tools is relieved. It is concluded that the main anti-collapse mechanisms of the CBM fuzzy-ball drilling fluid are to raise the coal strength, increase the formation resistance to fluid, and buffer the impact of

  3. Non-Spherical Gravitational Collapse of Strange Quark Matter

    Institute of Scientific and Technical Information of China (English)

    Zade S S; Patil K D; Mulkalwar P N

    2008-01-01

    We study the non-spherical gravitational collapse of the strange quark null fluid.The interesting feature which emerges is that the non-spherical collapse of charged strange quark matter leads to a naked singularity whereas the gravitational collapse of neutral quark matter proceeds to form a black hole.We extend the earlier work of Harko and Cheng[Phys.Lett.A 266 (2000) 249]to the non-spherical case.

  4. The dynamics of Affleck-Dine condensate collapse

    International Nuclear Information System (INIS)

    Enqvist, Kari; McDonald, John

    2000-01-01

    In the MSSM, cosmological scalar field condensates formed along flat directions of the scalar potential (Affleck-Dine condensates) are typically unstable with respect to formation of Q-balls, a type of non-topological soliton. We consider the dynamical evolution of the Affleck-Dine condensate in the MSSM. We discuss the creation and linear growth, in F- and D-term inflation models, of the quantum seed perturbations which in the non-linear regime catalyse the collapse of the condensate to non-topological soliton lumps. We study numerically the evolution of the collapsing condensate lumps and show that the solitons initially formed are not in general Q-balls, but Q-axitons, a pseudo-breather which can have very different properties from Q-balls of the same charge. We calculate the energy and charge radiated from a spherically symmetric condensate lump as it evolves into a Q-axiton. We also discuss the implications for baryogenesis and dark matter

  5. Ball Screw Actuator Including a Compliant Ball Screw Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2017-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  6. Study of film boiling collapse behavior during vapor explosion

    International Nuclear Information System (INIS)

    Yagi, Masahiro; Yamano, Norihiro; Sugimoto, Jun; Abe, Yutaka; Adachi, Hiromichi; Kobayashi, Tomoyoshi.

    1996-06-01

    Possible large scale vapor explosions are safety concern in nuclear power plants during severe accident. In order to identify the occurrence of the vapor explosion and to estimate the magnitude of the induced pressure pulse, it is necessary to investigate the triggering condition for the vapor explosion. As a first step of this study, scooping analysis was conducted with a simulation code based on thermal detonation model. It was found that the pressure at the collapse of film boiling much affects the trigger condition of vapor explosion. Based on this analytical results, basic experiments were conducted to clarify the collapse conditions of film boiling on a high temperature solid ball surface. Film boiling condition was established by flooding water onto a high temperature stainless steel ball heated by a high frequency induction heater. After the film boiling was established, the pressure pulse generated by a shock tube was applied to collapse the steam film on the ball surface. As the experimental boundary conditions, materials and size of the balls, magnitude of pressure pulse and initial temperature of the carbon and stainless steel balls were varied. The transients of pressure and surface temperature were measured. It was found that the surface temperature on the balls sharply decreased when the pressure wave passed through the film on balls. Based on the surface temperature behavior, the film boiling collapse pattern was found to be categorized into several types. Especially, the pattern for stainless steel ball was categorized into three types; no collapse, collapse and reestablishment after collapse. It was thus clarified that the film boiling collapse behavior was identified by initial conditions and that the pressure required to collapse film boiling strongly depended on the initial surface temperature. The present results will provide a useful information for the analysis of vapor explosions based on the thermal detonation model. (J.P.N.)

  7. WARM EXTENDED DENSE GAS AT THE HEART OF A COLD COLLAPSING DENSE CORE

    International Nuclear Information System (INIS)

    Shinnaga, Hiroko; Phillips, Thomas G.; Furuya, Ray S.; Kitamura, Yoshimi

    2009-01-01

    In order to investigate when and how the birth of a protostellar core occurs, we made survey observations of four well-studied dense cores in the Taurus molecular cloud using CO transitions in submillimeter bands. We report here the detection of unexpectedly warm (∼30-70 K), extended (radius of ∼2400 AU), dense (a few times 10 5 cm -3 ) gas at the heart of one of the dense cores, L1521F (MC27), within the cold dynamically collapsing components. We argue that the detected warm, extended, dense gas may originate from shock regions caused by collisions between the dynamically collapsing components and outflowing/rotating components within the dense core. We propose a new stage of star formation, 'warm-in-cold core stage (WICCS)', i.e., the cold collapsing envelope encases the warm extended dense gas at the center due to the formation of a protostellar core. WICCS would constitute a missing link in evolution between a cold quiescent starless core and a young protostar in class 0 stage that has a large-scale bipolar outflow.

  8. Collapse models with non-white noises

    International Nuclear Information System (INIS)

    Adler, Stephen L; Bassi, Angelo

    2007-01-01

    We set up a general formalism for models of spontaneous wavefunction collapse with dynamics represented by a stochastic differential equation driven by general Gaussian noises, not necessarily white in time. In particular, we show that the non-Schroedinger terms of the equation induce the collapse of the wavefunction to one of the common eigenstates of the collapsing operators, and that the collapse occurs with the correct quantum probabilities. We also develop a perturbation expansion of the solution of the equation with respect to the parameter which sets the strength of the collapse process; such an approximation allows one to compute the leading-order terms for the deviations of the predictions of collapse models with respect to those of standard quantum mechanics. This analysis shows that to leading order, the 'imaginary noise' trick can be used for non-white Gaussian noise

  9. Ceramic Rail-Race Ball Bearings

    Science.gov (United States)

    Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

    2010-01-01

    Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

  10. On the formation of ball lightning

    International Nuclear Information System (INIS)

    Silberg, P.A.

    1981-01-01

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which uner certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma. (author)

  11. Non explosive collapse of white dwarfs

    International Nuclear Information System (INIS)

    Canal, R.; Schatzmann, E.

    1976-01-01

    We show that if a sufficiently cold carbon-oxygen white dwarf, close to the critical mass, accretes matter from a companion in a binary system, the time scale of collapse is long enough to allow neutronization before the onset of pycnonuclear reactions. This can possibly lead to the formation of X-ray sources by a non explosive collapse. (orig.) [de

  12. Quantum gravitational collapse: non-singularity and non-locality

    International Nuclear Information System (INIS)

    Greenwood, Eric; Stojkovic, Dejan

    2008-01-01

    We investigate gravitational collapse in the context of quantum mechanics. We take primary interest in the behavior of the collapse near the horizon and near the origin (classical singularity) from the point of view of an infalling observer. In the absence of radiation, quantum effects near the horizon do not change the classical conclusions for an infalling observer, meaning the horizon is not an obstacle for him. However, quantum effects are able to remove the classical singularity at the origin, since the wave function is non-singular at the origin. Also, near the classical singularity, some non-local effects become important. In the Schrodinger equation describing behavior near the origin, derivatives of the wave function at one point are related to the value of the wave function at some other distant point.

  13. Optical and Acoustic Sensor-Based 3D Ball Motion Estimation for Ball Sport Simulators †

    Directory of Open Access Journals (Sweden)

    Sang-Woo Seo

    2018-04-01

    Full Text Available Estimation of the motion of ball-shaped objects is essential for the operation of ball sport simulators. In this paper, we propose an estimation system for 3D ball motion, including speed and angle of projection, by using acoustic vector and infrared (IR scanning sensors. Our system is comprised of three steps to estimate a ball motion: sound-based ball firing detection, sound source localization, and IR scanning for motion analysis. First, an impulsive sound classification based on the mel-frequency cepstrum and feed-forward neural network is introduced to detect the ball launch sound. An impulsive sound source localization using a 2D microelectromechanical system (MEMS microphones and delay-and-sum beamforming is presented to estimate the firing position. The time and position of a ball in 3D space is determined from a high-speed infrared scanning method. Our experimental results demonstrate that the estimation of ball motion based on sound allows a wider activity area than similar camera-based methods. Thus, it can be practically applied to various simulations in sports such as soccer and baseball.

  14. Non-singular Brans–Dicke collapse in deformed phase space

    Energy Technology Data Exchange (ETDEWEB)

    Rasouli, S.M.M., E-mail: mrasouli@ubi.pt [Departamento de Física, Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal); Centro de Matemática e Aplicações (CMA - UBI), Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal); Physics Group, Qazvin Branch, Islamic Azad University, Qazvin (Iran, Islamic Republic of); Ziaie, A.H., E-mail: ah_ziaie@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G. C., Evin, 19839 Tehran (Iran, Islamic Republic of); Department of Physics, Shahid Bahonar University, PO Box 76175, Kerman (Iran, Islamic Republic of); Jalalzadeh, S., E-mail: shahram.jalalzadeh@unila.edu.br [Federal University of Latin-American Integration, Technological Park of Itaipu PO box 2123, Foz do Iguaçu-PR, 85867-670 (Brazil); Moniz, P.V., E-mail: pmoniz@ubi.pt [Departamento de Física, Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal); Centro de Matemática e Aplicações (CMA - UBI), Universidade da Beira Interior, Rua Marquês d’Avila e Bolama, 6200 Covilhã (Portugal)

    2016-12-15

    We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans–Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature (Scheel, 1995), that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times.

  15. Non-singular Brans–Dicke collapse in deformed phase space

    International Nuclear Information System (INIS)

    Rasouli, S.M.M.; Ziaie, A.H.; Jalalzadeh, S.; Moniz, P.V.

    2016-01-01

    We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans–Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature (Scheel, 1995), that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times.

  16. Shock waves from non-spherically collapsing cavitation bubbles

    Science.gov (United States)

    Supponen, Outi; Obreschkow, Danail; Farhat, Mohamed

    2017-11-01

    Combining simultaneous high-speed imaging and hydrophone measurements, we uncover details of the multiple shock wave emission from laser-induced cavitation bubbles collapsing in a non-spherical way. For strongly deformed bubbles collapsing near a free surface, we identify the distinct shock waves caused by the jet impact onto the opposite bubble wall and by the individual collapses of the remaining bubble segments. The energy carried by each of these shocks depends on the level of bubble deformation, quantified by the anisotropy parameter ζ, the dimensionless equivalent of the Kelvin impulse. For jetting bubbles, at ζ water hammer as ph = 0.45 (ρc2 Δp) 1 / 2ζ-1 .

  17. A comparison of ball velocity in different kicking positions with dominant and non-dominant leg in junior soccer players

    Directory of Open Access Journals (Sweden)

    MÁRIO C. MARQUES

    2011-06-01

    Full Text Available Problem Statement: The aim of this study was to compare the ball velocity in different kicking conditions with dominant and non-dominant leg in junior soccer players.Approach: Sixteen junior soccer players (age 17.6±0.6yr, height 1.76±0.06m, and weight 67.9±5.2kg participated in this study. All participants kicked a soccer ball three times in seven conditions with the dominant and non-dominant leg. 1 Kicking the ball from 11m straight forwards, 2 and 3 kicking the ball from 11m to the left and right side of the goal, 4 and 5 kicking the ball straight forwards from 11m after a pass from the left and right side, 6 and 7 kicking the ball straight forwards from 11m after a pass that came from a diagonal position (45º from the left and right side. The highest ball velocity was used for analysis.Results: Significant differences were found in ball velocity between the dominant and non-dominant leg in all conditions (p<0.001. For the dominant leg also significant differences were found in the kicking of eleven meters (ideal conditions compared with: the perpendicular passing kick after the ball on the right (p=0.0024 and left (p=0.0080 and also with a diagonal kick after pass (45 ° of the ball on the right (p=0.0017 and left (p = 0.0381. Significant differences in the kicking with the non-dominant leg were found when kicking from eleven meters to the right side of the goal in comparison to: the kick under the same conditions, to the left side of the goal (p=0.0243 after pass and shot from the left side perpendicular (p=0.0222.Conclusions/Recommendations: kicking velocity is influenced very much under different conditions when kicking with the dominant leg while for the non-dominant leg this influence was small, because the non-dominant leg is less trained, so the values of velocity in different conditions, in addition to being the lowest, are closer than those obtained with the dominant leg

  18. Ball Screw Actuator Including an Axial Soft Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  19. Non self-similar collapses described by the non-linear Schroedinger equation

    International Nuclear Information System (INIS)

    Berge, L.; Pesme, D.

    1992-01-01

    We develop a rapid method in order to find the contraction rates of the radially symmetric collapsing solutions of the nonlinear Schroedinger equation defined for space dimensions exceeding a threshold value. We explicitly determine the asymptotic behaviour of these latter solutions by solving the non stationary linear problem relative to the nonlinear Schroedinger equation. We show that the self-similar states associated with the collapsing solutions are characterized by a spatial extent which is bounded from the top by a cut-off radius

  20. Tribological characteristics of Si3N4-based composites in unlubricated sliding against steel ball

    International Nuclear Information System (INIS)

    Liu, C.-C.; Huang, J.-L.

    2004-01-01

    The dry-sliding wear mechanism of Si 3 N 4 -based composites against AISI-52100 steel ball was studied using a ball-on-disc mode in a reciprocation motion. The addition of TiN particles can increase the fracture toughness of Si 3 N 4 -based composites. The fracture toughness of Si 3 N 4 -based composites played an important role for wear behavior. The Si 3 N 4 -based composites exhibits a small friction and wear coefficient compared to monolithic Si 3 N 4 . Atomic force microscopy (AFM) studies displayed fine wear grooves along the sliding traces. The subsurface deformation shows that the microcrack propagation extends along the TiN/Si 3 N 4 grain interface. The wear mechanisms were determined with scanning electron microscopy, transmission electron microscopy, X-ray diffraction and atomic force microscopy

  1. A comparison of static near stereo acuity in youth baseball/softball players and non-ball players.

    Science.gov (United States)

    Boden, Lauren M; Rosengren, Kenneth J; Martin, Daniel F; Boden, Scott D

    2009-03-01

    Although many aspects of vision have been investigated in professional baseball players, few studies have been performed in developing athletes. The issue of whether youth baseball players have superior stereopsis to nonplayers has not been addressed specifically. The purpose of this study was to determine if youth baseball/softball players have better stereo acuity than non-ball players. Informed consent was obtained from 51 baseball/softball players and 52 non-ball players (ages 10 to 18 years). Subjects completed a questionnaire, and their static near stereo acuity was measured using the Randot Stereotest (Stereo Optical Company, Chicago, Illinois). Stereo acuity was measured as the seconds of arc between the last pair of images correctly distinguished by the subject. The mean stereo acuity score was 25.5 +/- 1.7 seconds of arc in the baseball/softball players and 56.2 +/- 8.4 seconds of arc in the non-ball players. This difference was statistically significant (P softball players had significantly better static stereo acuity than non-ball players, comparable to professional ball players.

  2. Decay rates of Gaussian-type I-balls and Bose-enhancement effects in 3+1 dimensions

    International Nuclear Information System (INIS)

    Kawasaki, Masahiro; Yamada, Masaki

    2014-01-01

    I-balls/oscillons are long-lived spatially localized lumps of a scalar field which may be formed after inflation. In the scalar field theory with monomial potential nearly and shallower than quadratic, which is motivated by chaotic inflationary models and supersymmetric theories, the scalar field configuration of I-balls is approximately Gaussian. If the I-ball interacts with another scalar field, the I-ball eventually decays into radiation. Recently, it was pointed out that the decay rate of I-balls increases exponentially by the effects of Bose enhancement under some conditions and a non-perturbative method to compute the exponential growth rate has been derived. In this paper, we apply the method to the Gaussian-type I-ball in 3+1 dimensions assuming spherical symmetry, and calculate the partial decay rates into partial waves, labelled by the angular momentum of daughter particles. We reveal the conditions that the I-ball decays exponentially, which are found to depend on the mass and angular momentum of daughter particles and also be affected by the quantum uncertainty in the momentum of daughter particles

  3. Bifurcation of plasma balls and black holes to Lobed configurations

    International Nuclear Information System (INIS)

    Cardoso, Vitor; Dias, Oscar J.C.

    2009-01-01

    At high energy densities any quantum field theory is expected to have an effective hydrodynamic description. When combined with the gravity/gauge duality an unified picture emerges, where gravity itself can have a formal holographic hydrodynamic description. This provides a powerful tool to study black holes in a hydrodynamic setup. We study the stability of plasma balls, holographic duals of Scherck-Schwarz (SS) AdS black holes. We find that rotating plasma balls are unstable against m-lobed perturbations for rotation rates higher than a critical value. This unstable mode signals a bifurcation to a new branch of non-axisymmetric stationary solutions which resemble a 'peanut-like' rotating plasma. The gravitational dual of the rotating plasma ball must then be unstable and possibly decay to a non-axisymmetric long-lived SS AdS black hole. This instability provides therefore a mechanism that bounds the rotation of SS black holes. Our results are strictly valid for the SS AdS gravity theory dual to a SS gauge theory. The latter is particularly important because it shares common features with QCD, namely it is non-conformal, non-supersymmetric and has a confinement/deconfinement phase transition. We focus our analysis in 3-dimensional plasmas dual to SS AdS 5 black holes, but many of our results should extend to higher dimensions and to other gauge theory/gravity dualities with confined/deconfined phases and admitting a fluid description.

  4. Prevention of gravitational collapse

    International Nuclear Information System (INIS)

    Moffat, J.W.; Taylor, J.G.

    1981-01-01

    We apply a new theory of gravitation to the question of gravitational collapse to show that collapse is prevented in this theory under very reasonable conditions. This result also extends to prevent ultimate collapse of the Universe. (orig.)

  5. Effect of ball-milling to the surface morphology of CaCO3

    Science.gov (United States)

    Sulimai, N. H.; Rani, Rozina Abdul; Khusaimi, Z.; Abdullah, S.; Salifairus, M. J.; Alrokayan, Salman; Khan, Haseeb; Rusop, M.

    2018-05-01

    Calcium Carbonate can be synthesized in many approaches. This work studied on the physical changes to Calcium Carbonate (CaCO3) by ball-milling activity in different parameters; number of ball; collision duration; revolution per minute (RPM). Zirconia balls were used in the work because it has the best durability to withstand ball-milling conditions set. Industrial grade CaCO3 particles that were run in aforementioned parameters were characterized by Field Emission Scanning Electron Microscope (FE-SEM) to study the physical changes on the size and surface of the CaCO3. They were also characterized with Fourier Transform Infra-red Spectroscopy (FTIR) were fingerprint of CaCO3 regions were identified and any changes in the band position and intensity were discussed. Number of Zirconia balls and collision duration is directly proportional to the absorbance intensity whereas it is inversely proportional for the rpm. The best number of parameters producing the highest Absorbance is 100 Zirconia balls in duration of 1 hour and 100rpm.

  6. BALL - biochemical algorithms library 1.3

    Directory of Open Access Journals (Sweden)

    Stöckel Daniel

    2010-10-01

    Full Text Available Abstract Background The Biochemical Algorithms Library (BALL is a comprehensive rapid application development framework for structural bioinformatics. It provides an extensive C++ class library of data structures and algorithms for molecular modeling and structural bioinformatics. Using BALL as a programming toolbox does not only allow to greatly reduce application development times but also helps in ensuring stability and correctness by avoiding the error-prone reimplementation of complex algorithms and replacing them with calls into the library that has been well-tested by a large number of developers. In the ten years since its original publication, BALL has seen a substantial increase in functionality and numerous other improvements. Results Here, we discuss BALL's current functionality and highlight the key additions and improvements: support for additional file formats, molecular edit-functionality, new molecular mechanics force fields, novel energy minimization techniques, docking algorithms, and support for cheminformatics. Conclusions BALL is available for all major operating systems, including Linux, Windows, and MacOS X. It is available free of charge under the Lesser GNU Public License (LPGL. Parts of the code are distributed under the GNU Public License (GPL. BALL is available as source code and binary packages from the project web site at http://www.ball-project.org. Recently, it has been accepted into the debian project; integration into further distributions is currently pursued.

  7. Co-non-solvency: Mean-field polymer theory does not describe polymer collapse transition in a mixture of two competing good solvents

    Energy Technology Data Exchange (ETDEWEB)

    Mukherji, Debashish; Stuehn, Torsten; Kremer, Kurt [Max-Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany); Marques, Carlos M. [Max-Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany); Institut Charles Sadron, Université de Strasbourg, CNRS, Strasbourg (France)

    2015-03-21

    Smart polymers are a modern class of polymeric materials that often exhibit unpredictable behavior in mixtures of solvents. One such phenomenon is co-non-solvency. Co-non-solvency occurs when two (perfectly) miscible and competing good solvents, for a given polymer, are mixed together. As a result, the same polymer collapses into a compact globule within intermediate mixing ratios. More interestingly, polymer collapses when the solvent quality remains good and even gets increasingly better by the addition of the better cosolvent. This is a puzzling phenomenon that is driven by strong local concentration fluctuations. Because of the discrete particle based nature of the interactions, Flory-Huggins type mean field arguments become unsuitable. In this work, we extend the analysis of the co-non-solvency effect presented earlier [D. Mukherji et al., Nat. Commun. 5, 4882 (2014)]. We explain why co-non-solvency is a generic phenomenon, which can only be understood by the thermodynamic treatment of the competitive displacement of (co)solvent components. This competition can result in a polymer collapse upon improvement of the solvent quality. Specific chemical details are not required to understand these complex conformational transitions. Therefore, a broad range of polymers are expected to exhibit similar reentrant coil-globule-coil transitions in competing good solvents.

  8. Co-non-solvency: Mean-field polymer theory does not describe polymer collapse transition in a mixture of two competing good solvents

    International Nuclear Information System (INIS)

    Mukherji, Debashish; Stuehn, Torsten; Kremer, Kurt; Marques, Carlos M.

    2015-01-01

    Smart polymers are a modern class of polymeric materials that often exhibit unpredictable behavior in mixtures of solvents. One such phenomenon is co-non-solvency. Co-non-solvency occurs when two (perfectly) miscible and competing good solvents, for a given polymer, are mixed together. As a result, the same polymer collapses into a compact globule within intermediate mixing ratios. More interestingly, polymer collapses when the solvent quality remains good and even gets increasingly better by the addition of the better cosolvent. This is a puzzling phenomenon that is driven by strong local concentration fluctuations. Because of the discrete particle based nature of the interactions, Flory-Huggins type mean field arguments become unsuitable. In this work, we extend the analysis of the co-non-solvency effect presented earlier [D. Mukherji et al., Nat. Commun. 5, 4882 (2014)]. We explain why co-non-solvency is a generic phenomenon, which can only be understood by the thermodynamic treatment of the competitive displacement of (co)solvent components. This competition can result in a polymer collapse upon improvement of the solvent quality. Specific chemical details are not required to understand these complex conformational transitions. Therefore, a broad range of polymers are expected to exhibit similar reentrant coil-globule-coil transitions in competing good solvents

  9. Aerodynamic drag of modern soccer balls.

    Science.gov (United States)

    Asai, Takeshi; Seo, Kazuya

    2013-12-01

    Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 10(5) (drag coefficient, C d  ≈ 0.12), ~2.8 × 10(5) (C d  ≈ 0.13), ~3.3 × 10(5) (C d  ≈ 0.13), and ~2.4 × 10(5) (C d  ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces.

  10. Ball check valve

    International Nuclear Information System (INIS)

    Bevilacqua, F.

    1978-01-01

    A pressurized nuclear reactor having an instrument assembly sheathed in a metallic tube which is extended vertically upward into the reactor core by traversing a metallic guide tube which is welded to the wall of the vessel is described. Sensors in each instrument assembly are connected to instruments outside the vessel to manifest the conditions within the core. Each instrument assembly probe is moved into position within a metallic guide channel. The guide channel penetrates the wall of the vessel and forms part of the barrier to the environment within the pressure vessel. Each channel includes a ball check valve which is opened by the instrument assembly probe when the probe passes through the valve. A ball valve element is moved from its seat by the probe to a position lateral of the bore of the channel and is guided to its seat along a sloped path within the valve body when the probe is removed. 5 claims, 3 figures

  11. Compact Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D., E-mail: bazeia@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Losano, L.; Marques, M.A. [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Menezes, R. [Departamento de Ciências Exatas, Universidade Federal da Paraíba, 58297-000 Rio Tinto, PB (Brazil); Departamento de Física, Universidade Federal de Campina Grande, 58109-970 Campina Grande, PB (Brazil); Rocha, R. da [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, 09210-580 Santo André (Brazil)

    2016-07-10

    In this work we deal with non-topological solutions of the Q-ball type in two space–time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  12. Ball Screw Actuator Including a Stop with an Integral Guide

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Perek, John (Inventor); Geck, Kellan (Inventor)

    2015-01-01

    An actuator includes a housing assembly, a ball nut, a ball screw, and a ball screw stop. The ball nut is rotationally mounted in the housing assembly, is adapted to receive an input torque, and is configured, upon receipt thereof, to rotate and supply a drive force. The ball screw is mounted within the housing assembly and extends through the ball nut. The ball screw has a first end and a second end, and is coupled to receive the drive force from the ball nut. The ball screw is configured, upon receipt of the drive force, to selectively translate between a stow position and a deploy position. The ball screw stop is mounted on the ball screw to translate therewith and is configured to at selectively engage the housing assembly while the ball screw is translating, and engage the ball nut when the ball screw is in the deploy position.

  13. Two Balls' Collision of Mass Ratio 3:1

    Science.gov (United States)

    Ogawara, Yasuo; Hull, Michael M.

    2018-04-01

    Students will sometimes ask why momentum and kinetic energy concepts are both necessary. When physics teachers demonstrate situations that require both an understanding of kinetic energy and momentum, a favorite is Newton's cradle, or a comparable demonstration of two balls of equal mass hitting each other. However, in addition to the case of two balls of equal mass, if a ball hits another ball of three times the mass with equal speed, the results are also interesting, and, like the equal-mass demonstration, both kinetic energy and momentum are critical for understanding the motion.

  14. State-of-the-Art-Review of Collapsible Soils

    Directory of Open Access Journals (Sweden)

    A. A. AL-Rawas

    2000-12-01

    Full Text Available Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.

  15. Synthesis and gas-sensing characteristics of α-Fe2O3 hollow balls

    Directory of Open Access Journals (Sweden)

    Chu Manh Hung

    2016-03-01

    Full Text Available The synthesis of porous metal-oxide semiconductors for gas-sensing application is attracting increased interest. In this study, α-Fe2O3 hollow balls were synthesized using an inexpensive, scalable, and template-free hydrothermal method. The gas-sensing characteristics of the semiconductors were systematically investigated. Material characterization by XRD, SEM, HRTEM, and EDS reveals that single-phase α-Fe2O3 hollow balls with an average diameter of 1.5 μm were obtained. The hollow balls were formed by self assembly of α-Fe2O3 nanoparticles with an average diameter of 100 nm. The hollow structure and nanopores between the nanoparticles resulted in the significantly high response of the α-Fe2O3 hollow balls to ethanol at working temperatures ranging from 250 °C to 450 °C. The sensor also showed good selectivity over other gases, such as CO and NH3 promising significant application.

  16. Newton force from wave function collapse: speculation and test

    International Nuclear Information System (INIS)

    Diósi, Lajos

    2014-01-01

    The Diosi-Penrose model of quantum-classical boundary postulates gravity-related spontaneous wave function collapse of massive degrees of freedom. The decoherence effects of the collapses are in principle detectable if not masked by the overwhelming environmental decoherence. But the DP (or any other, like GRW, CSL) spontaneous collapses are not detectable themselves, they are merely the redundant formalism of spontaneous decoherence. To let DP collapses become testable physics, recently we extended the DP model and proposed that DP collapses are responsible for the emergence of the Newton gravitational force between massive objects. We identified the collapse rate, possibly of the order of 1/ms, with the rate of emergence of the Newton force. A simple heuristic emergence (delay) time was added to the Newton law of gravity. This non-relativistic delay is in peaceful coexistence with Einstein's relativistic theory of gravitation, at least no experimental evidence has so far surfaced against it. We derive new predictions of such a 'lazy' Newton law that will enable decisive laboratory tests with available technologies. The simple equation of 'lazy' Newton law deserves theoretical and experimental studies in itself, independently of the underlying quantum foundational considerations.

  17. Extended family childcare arrangements in a context of AIDS: collapse or adaptation?

    Science.gov (United States)

    Mathambo, Vuyiswa; Gibbs, Andy

    2009-01-01

    Families are subjected to a number of social, economic, political and demographic challenges. In recent years, the AIDS epidemic has constituted a major challenge for already poor families due to its wide reaching social, economic and health consequences. The devastating consequence of HIV and AIDS is being seen through the prolonged illness and death of family members of prime working age which impacts on family livelihoods and the ability to provide for and protect its members. This paper forms part of a review - commissioned by the Joint Learning Initiative on Children and HIV/AIDS - of qualitative studies of how families in southern Africa have changed, and are changing, as a result of the impact of HIV and AIDS. This paper presents results of how extended family childcare arrangements are changing as a result of the AIDS epidemic. In a southern African context, family denotes a wider array of relations than biological parents and their children - with children growing up amongst a multitude of relations sharing responsibility for their care and upbringing (Chirwa, 2002; Verhoef, 2005). Recently, there has been growing interest in the capacity of the extended family to care for the increasing number of children whose parents have died. However, literature on the role of the extended family in caring for orphaned children remains contradictory. One approach - the social rupture thesis (Chirwa, 2002) - suggests that the extended family network is collapsing under the strain of AIDS. On the other hand, families are portrayed as resilient and dynamic entities which are adapting their systems of childcare in response to the epidemic (Kuo,2007). In line with Abebe and Aase (2007) and Adams, Cekan, and Sauerborn (1998), this paper proposes a continuum of survival rather than a polarisation of extended family childcare arrangements.

  18. Non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} on dehydrogenation high-energy ball milled MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hou, Xiaojiang; Hu, Rui; Kou, Hongchao; Li, Jinshan

    2016-11-01

    MgH{sub 2}-M (M = TiF{sub 3} or Nb{sub 2}O{sub 5} or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH{sub 2} with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH{sub 2} with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF{sub 3} and Nb{sub 2}O{sub 5} evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH{sub 2} and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH{sub 2} reduce from 417 °C to 341 °C for TiF{sub 3} and from 417 °C to 336 °C for Nb{sub 2}O{sub 5}, respectively. The desorption peak temperature reaches as low as 310 °C for MgH{sub 2} catalyzed by TiF{sub 3} coupling with Nb{sub 2}O{sub 5}. The non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH{sub 2}. - Highlights: • Catalytic surface for MgH{sub 2} is achieved by high-energy ball milling. • Non-isothermal dehydrogenation behavior of MgH{sub 2} with TiF{sub 3} and/or Nb{sub 2}O{sub 5} is illustrated. • Dehydrogenation activation energies of synergetic catalyzed MgH{sub 2} are obtained. • Synergetic catalytic-dehydrogenation mechanism of TiF{sub 3} and Nb{sub 2}O{sub 5} is proposed.

  19. A self-similar magnetohydrodynamic model for ball lightnings

    International Nuclear Information System (INIS)

    Tsui, K. H.

    2006-01-01

    Ball lightning is modeled by magnetohydrodynamic (MHD) equations in two-dimensional spherical geometry with azimuthal symmetry. Dynamic evolutions in the radial direction are described by the self-similar evolution function y(t). The plasma pressure, mass density, and magnetic fields are solved in terms of the radial label η. This model gives spherical MHD plasmoids with axisymmetric force-free magnetic field, and spherically symmetric plasma pressure and mass density, which self-consistently determine the polytropic index γ. The spatially oscillating nature of the radial and meridional field structures indicate embedded regions of closed field lines. These regions are named secondary plasmoids, whereas the overall self-similar spherical structure is named the primary plasmoid. According to this model, the time evolution function allows the primary plasmoid expand outward in two modes. The corresponding ejection of the embedded secondary plasmoids results in ball lightning offering an answer as how they come into being. The first is an accelerated expanding mode. This mode appears to fit plasmoids ejected from thundercloud tops with acceleration to ionosphere seen in high altitude atmospheric observations of sprites and blue jets. It also appears to account for midair high-speed ball lightning overtaking airplanes, and ground level high-speed energetic ball lightning. The second is a decelerated expanding mode, and it appears to be compatible to slowly moving ball lightning seen near ground level. The inverse of this second mode corresponds to an accelerated inward collapse, which could bring ball lightning to an end sometimes with a cracking sound

  20. Non-stationary dynamics in the bouncing ball: A wavelet perspective

    Energy Technology Data Exchange (ETDEWEB)

    Behera, Abhinna K., E-mail: abhinna@iiserkol.ac.in; Panigrahi, Prasanta K., E-mail: pprasanta@iiserkol.ac.in [Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246 (India); Sekar Iyengar, A. N., E-mail: ansekar.iyengar@saha.ac.in [Plasma Physics Division, Saha Institute of Nuclear Physics (SINP), Sector 1, Block-AF, Bidhannagar, Kolkata 700064 (India)

    2014-12-01

    The non-stationary dynamics of a bouncing ball, comprising both periodic as well as chaotic behavior, is studied through wavelet transform. The multi-scale characterization of the time series displays clear signatures of self-similarity, complex scaling behavior, and periodicity. Self-similar behavior is quantified by the generalized Hurst exponent, obtained through both wavelet based multi-fractal detrended fluctuation analysis and Fourier methods. The scale dependent variable window size of the wavelets aptly captures both the transients and non-stationary periodic behavior, including the phase synchronization of different modes. The optimal time-frequency localization of the continuous Morlet wavelet is found to delineate the scales corresponding to neutral turbulence, viscous dissipation regions, and different time varying periodic modulations.

  1. Petrography and microanalysis of Pennsylvanian coal-ball concretions (Herrin Coal, Illinois Basin, USA): Bearing on fossil plant preservation and coal-ball origins

    Science.gov (United States)

    Siewers, Fredrick D.; Phillips, Tom L.

    2015-11-01

    Petrographic analyses of 25 coal balls from well-studied paleobotanical profiles in the Middle Pennsylvanian Herrin Coal (Westphalian D, Illinois Basin) and five select coal balls from university collections, indicate that Herrin Coal-ball peats were permineralized by fibrous and non-fibrous carbonates. Fibrous carbonates occur in fan-like to spherulitic arrays in many intracellular (within tissue) pores, and are best developed in relatively open extracellular (between plant) pore spaces. Acid etched fibrous carbonates appear white under reflected light and possess a microcrystalline texture attributable to abundant microdolomite. Scanning electron microscopy, X-ray diffraction, and electron microprobe analysis demonstrate that individual fibers have a distinct trigonal prism morphology and are notable for their magnesium content (≈ 9-15 mol% MgCO3). Non-fibrous carbonates fill intercrystalline spaces among fibers and pores within the peat as primary precipitates and neomorphic replacements. In the immediate vicinity of plant cell walls, non-fibrous carbonates cut across fibrous carbonates as a secondary, neomorphic phase attributed to coalification of plant cell walls. Dolomite occurs as diagenetic microdolomite associated with the fibrous carbonate phase, as sparite replacements, and as void-filling cement. Maximum dolomite (50-59 wt.%) is in the top-of-seam coal-ball zone at the Sahara Mine, which is overlain by the marine Anna Shale. Coal-ball formation in the Herrin Coal began with the precipitation of fibrous high magnesium calcite. The trigonal prism morphology of the carbonate fibers suggests rapid precipitation from super-saturated, meteoric pore waters. Carbonate precipitation from marine waters is discounted on the basis of stratigraphic, paleobotanical, and stable isotopic evidence. Most non-fibrous carbonate is attributable to later diagenetic events, including void-fill replacements, recrystallization, and post-depositional fracture fills. Evidence

  2. Relation Between Hertz Stress-Life Exponent, Ball-Race Conformity, and Ball Bearing Life

    Science.gov (United States)

    Zaretsky, Erwin V.; Poplawski, Joseph V.; Root, Lawrence E.

    2008-01-01

    ANSI/ABMA and ISO standards based on Lundberg-Palmgren bearing life theory are normalized for ball bearings having inner- and outerrace conformities of 52 percent (0.52) and made from pre-1940 bearing steel. The Lundberg-Palmgren theory incorporates an inverse 9th power relation between Hertz stress and fatigue life for ball bearings. The effect of race conformity on ball set life independent of race life is not incorporated into the Lundberg-Palmgren theory. In addition, post-1960 vacuum-processed bearing steel exhibits a 12th power relation between Hertz stress and life. The work reported extends the previous work of Zaretsky, Poplawski, and Root to calculate changes in bearing life--that includes the life of the ball set--caused by race conformity, Hertz stress-life exponent, ball bearing type and bearing series. The bearing fatigue life in actual application will usually be equal to or greater than that calculated using the ANSI/ABMA and ISO standards that incorporate the Lundberg-Palmgren theory. The relative fatigue life of an individual race is more sensitive to changes in race conformity for Hertz stress-life exponent n of 12 than where n = 9. However, when the effects are combined to predict actual bearing life for a specified set of conditions and bearing geometry, the predicted life of the bearing will be greater for a value of n = 12 than n = 9.

  3. FEAST 3.1: finite-element modeling of sheath deformation such as longitudinal ridging and collapse into axial gap

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Xu, Z.; Kim, Y-S.; Lai, L.; Cheng, G.; Xu, S. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada)

    2010-07-01

    During normal operation, the collapsible CANDU® fuel sheath deforms, especially, it may deform into longitudinal ridges or collapse instantaneously into the axial gaps between the end pellet and endcap or between two neighbouring pellets. These phenomena occur under certain conditions, such as the coolant pressure exceeding critical pressures for longitudinal ridging or axial collapse. Both longitudinal ridging and axial collapse phenomena result from plastic instability in the sheath under coolant pressure. Longitudinal ridging features one or multiple lobes or 'ridges' (outward from the sheath surface) formed along the sheath in the longitudinal direction. Axial collapse features a 'valley' around the sheath circumference. Both phenomena can lead to sheath overstrain, which in turn potentially leads to sheath failure. The LONGER code, which contains empirical correlations, has been used to predict the critical pressures for these two sheath deformation phenomena. To study fuel behaviour outside of the application ranges of the LONGER empirical correlations, a mechanistic model is needed. FEAST (Finite Element Analysis for Stresses) is an AECL computer code used to assess the structural integrity of the CANDU fuel element. The FEAST code has recently been developed (to Version 3.1) to model processes occurring during longitudinal ridge formation and instantaneous collapse into the axial gap. The new models include those for geometric non-linearity (large deformation, large material rotation), non-linear stress-strain curve for plastic deformation, Zr-4 sheath creep law, and variable Young’s Modulus etc. This paper describes the mechanistic model (FEAST 3.1) development for analyses of longitudinal ridging and instantaneous collapse into axial gap, and the comparison with the results from empirical correlations in LONGER. (author)

  4. FEAST 3.1: finite-element modeling of sheath deformation such as longitudinal ridging and collapse into axial gap

    International Nuclear Information System (INIS)

    Wang, X.; Xu, Z.; Kim, Y-S.; Lai, L.; Cheng, G.; Xu, S.

    2010-01-01

    During normal operation, the collapsible CANDU® fuel sheath deforms, especially, it may deform into longitudinal ridges or collapse instantaneously into the axial gaps between the end pellet and endcap or between two neighbouring pellets. These phenomena occur under certain conditions, such as the coolant pressure exceeding critical pressures for longitudinal ridging or axial collapse. Both longitudinal ridging and axial collapse phenomena result from plastic instability in the sheath under coolant pressure. Longitudinal ridging features one or multiple lobes or 'ridges' (outward from the sheath surface) formed along the sheath in the longitudinal direction. Axial collapse features a 'valley' around the sheath circumference. Both phenomena can lead to sheath overstrain, which in turn potentially leads to sheath failure. The LONGER code, which contains empirical correlations, has been used to predict the critical pressures for these two sheath deformation phenomena. To study fuel behaviour outside of the application ranges of the LONGER empirical correlations, a mechanistic model is needed. FEAST (Finite Element Analysis for Stresses) is an AECL computer code used to assess the structural integrity of the CANDU fuel element. The FEAST code has recently been developed (to Version 3.1) to model processes occurring during longitudinal ridge formation and instantaneous collapse into the axial gap. The new models include those for geometric non-linearity (large deformation, large material rotation), non-linear stress-strain curve for plastic deformation, Zr-4 sheath creep law, and variable Young’s Modulus etc. This paper describes the mechanistic model (FEAST 3.1) development for analyses of longitudinal ridging and instantaneous collapse into axial gap, and the comparison with the results from empirical correlations in LONGER. (author)

  5. The collapse of a molecular cloud core to stellar densities using radiation non-ideal magnetohydrodynamics

    Science.gov (United States)

    Wurster, James; Bate, Matthew R.; Price, Daniel J.

    2018-04-01

    We present results from radiation non-ideal magnetohydrodynamics (MHD) calculations that follow the collapse of rotating, magnetized, molecular cloud cores to stellar densities. These are the first such calculations to include all three non-ideal effects: ambipolar diffusion, Ohmic resistivity, and the Hall effect. We employ an ionization model in which cosmic ray ionization dominates at low temperatures and thermal ionization takes over at high temperatures. We explore the effects of varying the cosmic ray ionization rate from ζcr = 10-10 to 10-16 s-1. Models with ionization rates ≳10-12 s-1 produce results that are indistinguishable from ideal MHD. Decreasing the cosmic ray ionization rate extends the lifetime of the first hydrostatic core up to a factor of 2, but the lifetimes are still substantially shorter than those obtained without magnetic fields. Outflows from the first hydrostatic core phase are launched in all models, but the outflows become broader and slower as the ionization rate is reduced. The outflow morphology following stellar core formation is complex and strongly dependent on the cosmic ray ionization rate. Calculations with high ionization rates quickly produce a fast (≈14 km s-1) bipolar outflow that is distinct from the first core outflow, but with the lowest ionization rate, a slower (≈3-4 km s-1) conical outflow develops gradually and seamlessly merges into the first core outflow.

  6. Cylindrical collapse and gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)

    2005-06-21

    We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.

  7. AM06-25-004 3-D analysis of sports ball flight trajectory by high speed camera

    OpenAIRE

    溝田, 武人; 小倉, 聡樹; Taketo, MIZOTA; Satoki, OGURA; 福岡工大; 福岡工大:(現)(株)日立建機アルバ; FIT; FIT

    2006-01-01

    Outdoor experiments of valley ball and soccer ball free fall are conducted at Aso choyo big bridge. High speed camera captured these 3-D trajectories of ball fall process. Image processing of these pictures and Newton's equation of motion were available to clarify unsteady lift C_L and side force C_S. Strouhal number concerning of these sports balls, which are estimated by the unsteady air force, implies that the wavy motion of the balls are a kind of flutter phenomena by wake perturbation an...

  8. Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm2O3 Powder Mixtures during Ball Milling

    Directory of Open Access Journals (Sweden)

    Yong Luo

    2016-10-01

    Full Text Available The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt % Tm2O3 powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm2O3 was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt % Tm2O3, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O solid solution.

  9. Hermitian harmonic maps into convex balls

    International Nuclear Information System (INIS)

    Li Zhenyang; Xi Zhang

    2004-07-01

    In this paper, we consider Hermitian harmonic maps from Hermitian manifolds into convex balls. We prove that there exist no non-trivial Hermitian harmonic maps from closed Hermitian manifolds into convex balls, and we use the heat flow method to solve the Dirichlet problem for Hermitian harmonic maps when the domain is compact Hermitian manifold with non-empty boundary. The case where the domain manifold is complete(noncompact) is also studied. (author)

  10. On the quantum corrected gravitational collapse

    International Nuclear Information System (INIS)

    Torres, Ramón; Fayos, Francesc

    2015-01-01

    Based on a previously found general class of quantum improved exact solutions composed of non-interacting (dust) particles, we model the gravitational collapse of stars. As the modeled star collapses a closed apparent 3-horizon is generated due to the consideration of quantum effects. The effect of the subsequent emission of Hawking radiation related to this horizon is taken into consideration. Our computations lead us to argue that a total evaporation could be reached. The inferred global picture of the spacetime corresponding to gravitational collapse is devoid of both event horizons and shell-focusing singularities. As a consequence, there is no information paradox and no need of firewalls

  11. On the quantum corrected gravitational collapse

    Directory of Open Access Journals (Sweden)

    Ramón Torres

    2015-07-01

    Full Text Available Based on a previously found general class of quantum improved exact solutions composed of non-interacting (dust particles, we model the gravitational collapse of stars. As the modeled star collapses a closed apparent 3-horizon is generated due to the consideration of quantum effects. The effect of the subsequent emission of Hawking radiation related to this horizon is taken into consideration. Our computations lead us to argue that a total evaporation could be reached. The inferred global picture of the spacetime corresponding to gravitational collapse is devoid of both event horizons and shell-focusing singularities. As a consequence, there is no information paradox and no need of firewalls.

  12. On the quantum corrected gravitational collapse

    Science.gov (United States)

    Torres, Ramón; Fayos, Francesc

    2015-07-01

    Based on a previously found general class of quantum improved exact solutions composed of non-interacting (dust) particles, we model the gravitational collapse of stars. As the modeled star collapses a closed apparent 3-horizon is generated due to the consideration of quantum effects. The effect of the subsequent emission of Hawking radiation related to this horizon is taken into consideration. Our computations lead us to argue that a total evaporation could be reached. The inferred global picture of the spacetime corresponding to gravitational collapse is devoid of both event horizons and shell-focusing singularities. As a consequence, there is no information paradox and no need of firewalls.

  13. Magnetoresistivity and microstructure of YBa2Cu3Oy prepared using planetary ball milling

    International Nuclear Information System (INIS)

    Hamrita, A.; Ben Azzouz, F.; Madani, A.; Ben Salem, M.

    2012-01-01

    Superconducting properties of YBa 2 Cu 3 O y prepared using planetary ball milling were studied. Y-deficient YBa 2 Cu 3 O y nanoparticles are embedded in the superconducting matrix. Ball milled sample exhibits a large magnetoresistivity in weak magnetic fields at 77 K. We have studied the microstructure and the magnetoresistivity of polycrystalline YBa 2 Cu 3 O y (YBCO or Y-123 for brevity) embedded with nanoparticles of Y-deficient YBCO, generated by the planetary ball milling technique. Bulk samples were synthesized from a precursor YBCO powder, which was prepared from commercial high purity Y 2 O 3 , Ba 2 CO 3 and CuO via a one-step annealing process in air at 950 °C. After planetary ball milling of the precursor, the powder was uniaxially pressed and subsequently annealed at 950 °C in air. Phase analysis by X-ray diffraction (XRD), granular structure examination by scanning electron microscopy (SEM), microstructure investigation by transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDXS) were carried out. TEM analyses show that nanoparticles of Y-deficient YBCO, generated by ball milling, are embedded in the superconducting matrix. Electrical resistance as a function of temperature, ρ(T), revealed that the zero resistance temperature, T co , is 84.5 and 90 K for the milled and unmilled samples respectively. The milled ceramics exhibit a large magnetoresistance in weak magnetic fields at liquid nitrogen temperature. This attractive effect is of high significance as it makes these materials promising candidates for practical application in magnetic field sensor devices.

  14. Creep collapse of TAPS fuel cladding

    International Nuclear Information System (INIS)

    Chaudhry, S.M.; Anand, A.K.

    1975-01-01

    Densification of UO 2 can cause axial gaps between fuel pelets and cladding in unsupported (internally) at these regions. An analysis is carried out regarding the possibility of creep collapse in these regions. The analysis is based on Timoshenko's theory of collapse. At various times during the residence of fuel in reactor following parameters are calculated : (1) inelastic collapse of perfectly circular tubes (2) plastic instability in oval tubes (3) effect of creep on ovality. Creep is considered to be a non-linear combination of the following : (a) thermal creep (b) intresenic creep (c) stress aided radiation enhanced (d) stress free growth (4) Critical pressure ratio. The results obtained are compared with G.E. predictions. The results do not predict collapse of TAPS fuel cladding for five year residence time. (author)

  15. On the gravitational collapse of a gas cloud in the presence of bulk viscosity

    International Nuclear Information System (INIS)

    Carlevaro, Nakia; Montani, Giovanni

    2005-01-01

    We analyse the effects induced by the bulk (or second) viscosity on the dynamics associated with the extreme gravitational collapse. The aim of the work is to investigate whether the presence of viscous corrections to the evolution of a collapsing gas cloud influences the top-down fragmentation process. To this end, we generalize the approach presented by Hunter (1962 Astrophys. J. 136 594) to include in the dynamics of the (uniform and spherically symmetric) cloud the negative pressure contribution associated with the bulk viscosity phenomenology. Within the framework of a Newtonian approach (whose range of validity is outlined), we extend to the viscous case either the Lagrangian or the Eulerian motion of the system addressed in Hunter (1962 Astrophys. J. 136 594) and we treat the asymptotic evolution in correspondence with a viscosity coefficient of the form ζ = ζ 0 ρ 5/6 (ρ being the cloud density and ζ 0 = const). We show how the adiabatic-like behaviour of the gas (i.e. when the polytropic index γ takes values 4/3 < γ ≤ 5/3) is deeply influenced by viscous correction when its collapse reaches the extreme regime toward the singularity. In fact, for sufficiently large viscous contributions, density contrasts associated with a given scale of the fragmentation process acquire, asymptotically, a vanishing behaviour which prevents the formation of sub-structures. Since in the non-dissipative case density contrasts diverge (except for the purely adiabatic behaviour γ = 5/3 in which they remain constant), we can conclude that in the adiabatic-like collapse the top-down mechanism of structure formation is suppressed as soon as enough strong viscous effects are taken into account. Such a feature is not present in the isothermal-like (i.e. 1 ≤ γ < 4/3) collapse because the sub-structure formation is yet present and outlines the same behaviour as in the non-viscous case. We emphasize that in the adiabatic-like collapse the bulk viscosity is also responsible

  16. Influence of Temperature on the Performance of LiNi1/3Co1/3Mn1/3O2 Prepared by High-Temperature Ball-Milling Method

    Directory of Open Access Journals (Sweden)

    Ming Tian

    2018-01-01

    Full Text Available Aiming at the preparation of high electrochemical performance LiNi1/3Co1/3Mn1/3O2 cathode material for lithium-ion battery, LiNi1/3Co1/3Mn1/3O2 was prepared with lithium carbonate, nickel (II oxide, cobalt (II, III oxide, and manganese dioxide as raw materials by high-temperature ball-milling method. Influence of ball-milling temperature was investigated in this work. It was shown that the fine LiNi1/3Co1/3Mn1/3O2 powder with high electrochemical performance can be produced by the high-temperature ball-milling process, and the optimal ball-milling temperature obtained in the current study was 750°C. Its initial discharge capacity was 146.0 mAhg−1 at the rate of 0.1 C, and over 50 cycles its capacity retention rate was 90.2%.

  17. Explosive X-point collapse in relativistic magnetically dominated plasma

    Science.gov (United States)

    Lyutikov, Maxim; Sironi, Lorenzo; Komissarov, Serguei S.; Porth, Oliver

    2017-12-01

    The extreme properties of the gamma-ray flares in the Crab nebula present a clear challenge to our ideas on the nature of particle acceleration in relativistic astrophysical plasma. It seems highly unlikely that standard mechanisms of stochastic type are at work here and hence the attention of theorists has switched to linear acceleration in magnetic reconnection events. In this series of papers, we attempt to develop a theory of explosive magnetic reconnection in highly magnetized relativistic plasma which can explain the extreme parameters of the Crab flares. In the first paper, we focus on the properties of the X-point collapse. Using analytical and numerical methods (fluid and particle-in-cell simulations) we extend Syrovatsky's classical model of such collapse to the relativistic regime. We find that the collapse can lead to the reconnection rate approaching the speed of light on macroscopic scales. During the collapse, the plasma particles are accelerated by charge-starved electric fields, which can reach (and even exceed) values of the local magnetic field. The explosive stage of reconnection produces non-thermal power-law tails with slopes that depend on the average magnetization . For sufficiently high magnetizations and vanishing guide field, the non-thermal particle spectrum consists of two components: a low-energy population with soft spectrum that dominates the number census; and a high-energy population with hard spectrum that possesses all the properties needed to explain the Crab flares.

  18. Ball milled bauxite residue as a reinforcing filler in phosphate-based intumescent system

    Directory of Open Access Journals (Sweden)

    Adiat Ibironke Arogundade

    2018-01-01

    Full Text Available Bauxite residue (BR is an alumina refinery waste with a global disposal problem. Of the 120 MT generated annually, only 3 MT is disposed via utilization. One of the significant challenges to sustainable utilization has been found to be the cost of processing. In this work, using ball milling, we achieved material modification of bauxite residue. Spectrometric imaging with FESEM showed the transformation from an aggregate structure to nano, platy particulates, leading to particle size homogeneity. BET analysis showed surface area was increased by 23%, while pH was reduced from 10.8 to 9.1 due to collapsing of the hydroxyl surface by the fracturing action of the ball mill. Incorporation of this into a phosphate-based fire retardant, intumescent formulation led to improved material dispersion and the formation of reinforcing heat shielding char nodules. XRD revealed the formation of ceramic metal phosphates which acted as an additional heat sink to the intumescent system, thereby reducing char oxidation and heat transfer to the substrate. Steel substrate temperature from a Bunsen burner test reduced by 33%. Therefore, ball milling can serve as a simple, low-cost processing route for the reuse of bauxite residue in intumescent composites.

  19. MolPrint3D: Enhanced 3D Printing of Ball-and-Stick Molecular Models

    Science.gov (United States)

    Paukstelis, Paul J.

    2018-01-01

    The increased availability of noncommercial 3D printers has provided instructors and students improved access to printing technology. However, printing complex ball-and-stick molecular structures faces distinct challenges, including the need for support structures that increase with molecular complexity. MolPrint3D is a software add-on for the…

  20. Gravitational Waves from Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Chris L. Fryer

    2011-01-01

    Full Text Available Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  1. Gravitational waves from gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Christopher L [Los Alamos National Laboratory; New, Kimberly C [Los Alamos National Laboratory

    2008-01-01

    Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  2. Acoustic monitoring of a ball sinking in vibrated granular sediments

    Science.gov (United States)

    van den Wildenberg, Siet; Léopoldès, Julien; Tourin, Arnaud; Jia, Xiaoping

    2017-06-01

    We develop an ultrasound probing to investigate the dynamics of a high density ball sinking in 3D opaque dense granular suspensions under horizontal weak vibrations. We show that the motion of the ball in these horizontally vibrated glass bead packings saturated by water is consistent with the frictional rheology. The extracted stress-strain relation evidences an evolution of flow behaviour from frictional creep to inertial regimes. Our main finding is that weak external vibration primarily affects the yield stress and controls the depth of sinking via vibration-induced sliding at the grain contact. Also, we observe that the extracted rheological parameters depend on the size of the probing ball, suggesting thus a non-local rheology.

  3. Fe-Al2O3 nanocomposites prepared by high-energy ball milling

    DEFF Research Database (Denmark)

    Linderoth, Søren; Pedersen, M.S.

    1994-01-01

    Nanocomposites of alpha-Fe and alpha-Al2O3, prepared by high-energy ball milling, exhibit coercivities which are enhanced by about two orders of magnitude with respect to the bulk value. The degree of enhancement depends on the volume fraction (x(upsilon)) of Fe, with a maximum for x(upsilon) alm......Nanocomposites of alpha-Fe and alpha-Al2O3, prepared by high-energy ball milling, exhibit coercivities which are enhanced by about two orders of magnitude with respect to the bulk value. The degree of enhancement depends on the volume fraction (x(upsilon)) of Fe, with a maximum for x...

  4. Reviews Book: Extended Project Student Guide Book: My Inventions Book: ASE Guide to Research in Science Education Classroom Video: The Science of Starlight Software: SPARKvue Book: The Geek Manifesto Ebook: A Big Ball of Fire Apps

    Science.gov (United States)

    2014-05-01

    WE RECOMMEND Level 3 Extended Project Student Guide A non-specialist, generally useful and nicely put together guide to project work ASE Guide to Research in Science Education Few words wasted in this handy introduction and reference The Science of Starlight Slow but steady DVD covers useful ground SPARKvue Impressive software now available as an app WORTH A LOOK My Inventions and Other Writings Science, engineering, autobiography, visions and psychic phenomena mixed in a strange but revealing concoction The Geek Manifesto: Why Science Matters More enthusiasm than science, but a good motivator and interesting A Big Ball of Fire: Your questions about the Sun answered Free iTunes download made by and for students goes down well APPS Collider visualises LHC experiments ... Science Museum app enhances school trips ... useful information for the Cambridge Science Festival

  5. Investigation of Seismic Waves from Non-Natural Sources: A Case Study for Building Collapse and Surface Explosion

    Science.gov (United States)

    Houng, S.; Hong, T.

    2013-12-01

    The nature and excitation mechanism of incidents or non-natural events have been widely investigated using seismological techniques. With introduction of dense seismic networks, small-sized non-natural events such as building collapse and chemical explosions are well recorded. Two representative non-natural seismic sources are investigated. A 5-story building in South Korea, Sampoong department store, was collapsed in June 25, 1995, causing casualty of 1445. This accident is known to be the second deadliest non-terror-related building collapse in the world. The event was well recorded by a local station in ~ 9 km away. P and S waves were recorded weak, while monotonic Rayleigh waves were observed well. The origin time is determined using surface-wave arrival time. The magnitude of event is determined to be 1.2, which coincides with a theoretical estimate based on the mass and volume of building. Synthetic waveforms are modeled for various combinations of velocity structures and source time functions, which allow us to constrain the process of building collapse. It appears that the building was collapsed once within a couple of seconds. We also investigate a M2.1 chemical explosion at a fertilizer plant in Texas on April 18, 2013. It was reported that more than one hundred people were dead or injured by the explosion. Seismic waveforms for nearby stations are collected from Incorporated Research Institution of Seismology (IRIS). The event was well recorded at stations in ~500 km away from the source. Strong acoustic signals were observed at stations in a certain great-circle direction. This observation suggests preferential propagation of acoustic waves depending on atmospheric environment. Waveform cross-correlation, spectral analysis and waveform modeling are applied to understand the source physics. We discuss the nature of source and source excitation mechanism.

  6. Gravitational Waves from Gravitational Collapse.

    Science.gov (United States)

    Fryer, Chris L; New, Kimberly C B

    2011-01-01

    Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars. Supplementary material is available for this article at 10.12942/lrr-2011-1.

  7. RadBall Technology Testing and MCNP Modeling of the Tungsten Collimator.

    Science.gov (United States)

    Farfán, Eduardo B; Foley, Trevor Q; Coleman, J Rusty; Jannik, G Timothy; Holmes, Christopher J; Oldham, Mark; Adamovics, John; Stanley, Steven J

    2010-01-01

    The United Kingdom's National Nuclear Laboratory (NNL) has developed a remote, non-electrical, radiation-mapping device known as RadBall(™), which can locate and quantify radioactive hazards within contaminated areas of the nuclear industry. RadBall(™) consists of a colander-like outer shell that houses a radiation-sensitive polymer sphere. The outer shell works to collimate radiation sources and those areas of the polymer sphere that are exposed react, becoming increasingly more opaque, in proportion to the absorbed dose. The polymer sphere is imaged in an optical-CT scanner, which produces a high resolution 3D map of optical attenuation coefficients. Subsequent analysis of the optical attenuation matrix provides information on the spatial distribution of sources in a given area forming a 3D characterization of the area of interest. RadBall(™) has no power requirements and can be positioned in tight or hard-to reach locations. The RadBall(™) technology has been deployed in a number of technology trials in nuclear waste reprocessing plants at Sellafield in the United Kingdom and facilities of the Savannah River National Laboratory (SRNL). This study focuses on the RadBall(™) testing and modeling accomplished at SRNL.

  8. Timescales of isotropic and anisotropic cluster collapse

    Science.gov (United States)

    Bartelmann, M.; Ehlers, J.; Schneider, P.

    1993-12-01

    From a simple estimate for the formation time of galaxy clusters, Richstone et al. have recently concluded that the evidence for non-virialized structures in a large fraction of observed clusters points towards a high value for the cosmological density parameter Omega0. This conclusion was based on a study of the spherical collapse of density perturbations, assumed to follow a Gaussian probability distribution. In this paper, we extend their treatment in several respects: first, we argue that the collapse does not start from a comoving motion of the perturbation, but that the continuity equation requires an initial velocity perturbation directly related to the density perturbation. This requirement modifies the initial condition for the evolution equation and has the effect that the collapse proceeds faster than in the case where the initial velocity perturbation is set to zero; the timescale is reduced by a factor of up to approximately equal 0.5. Our results thus strengthens the conclusion of Richstone et al. for a high Omega0. In addition, we study the collapse of density fluctuations in the frame of the Zel'dovich approximation, using as starting condition the analytically known probability distribution of the eigenvalues of the deformation tensor, which depends only on the (Gaussian) width of the perturbation spectrum. Finally, we consider the anisotropic collapse of density perturbations dynamically, again with initial conditions drawn from the probability distribution of the deformation tensor. We find that in both cases of anisotropic collapse, in the Zel'dovich approximation and in the dynamical calculations, the resulting distribution of collapse times agrees remarkably well with the results from spherical collapse. We discuss this agreement and conclude that it is mainly due to the properties of the probability distribution for the eigenvalues of the Zel'dovich deformation tensor. Hence, the conclusions of Richstone et al. on the value of Omega0 can be

  9. THE THREE-DIMENSIONAL EVOLUTION TO CORE COLLAPSE OF A MASSIVE STAR

    Energy Technology Data Exchange (ETDEWEB)

    Couch, Sean M. [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, CA 91125 (United States); Chatzopoulos, Emmanouil [Flash Center for Computational Science, Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Arnett, W. David [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Timmes, F. X., E-mail: smc@tapir.caltech.edu [Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)

    2015-07-20

    We present the first three-dimensional (3D) simulation of the final minutes of iron core growth in a massive star, up to and including the point of core gravitational instability and collapse. We capture the development of strong convection driven by violent Si burning in the shell surrounding the iron core. This convective burning builds the iron core to its critical mass and collapse ensues, driven by electron capture and photodisintegration. The non-spherical structure and motion generated by 3D convection is substantial at the point of collapse, with convective speeds of several hundreds of km s{sup −1}. We examine the impact of such physically realistic 3D initial conditions on the core-collapse supernova mechanism using 3D simulations including multispecies neutrino leakage and find that the enhanced post-shock turbulence resulting from 3D progenitor structure aids successful explosions. We conclude that non-spherical progenitor structure should not be ignored, and should have a significant and favorable impact on the likelihood for neutrino-driven explosions. In order to make simulating the 3D collapse of an iron core feasible, we were forced to make approximations to the nuclear network making this effort only a first step toward accurate, self-consistent 3D stellar evolution models of the end states of massive stars.

  10. THE THREE-DIMENSIONAL EVOLUTION TO CORE COLLAPSE OF A MASSIVE STAR

    International Nuclear Information System (INIS)

    Couch, Sean M.; Chatzopoulos, Emmanouil; Arnett, W. David; Timmes, F. X.

    2015-01-01

    We present the first three-dimensional (3D) simulation of the final minutes of iron core growth in a massive star, up to and including the point of core gravitational instability and collapse. We capture the development of strong convection driven by violent Si burning in the shell surrounding the iron core. This convective burning builds the iron core to its critical mass and collapse ensues, driven by electron capture and photodisintegration. The non-spherical structure and motion generated by 3D convection is substantial at the point of collapse, with convective speeds of several hundreds of km s −1 . We examine the impact of such physically realistic 3D initial conditions on the core-collapse supernova mechanism using 3D simulations including multispecies neutrino leakage and find that the enhanced post-shock turbulence resulting from 3D progenitor structure aids successful explosions. We conclude that non-spherical progenitor structure should not be ignored, and should have a significant and favorable impact on the likelihood for neutrino-driven explosions. In order to make simulating the 3D collapse of an iron core feasible, we were forced to make approximations to the nuclear network making this effort only a first step toward accurate, self-consistent 3D stellar evolution models of the end states of massive stars

  11. Research in nuclear astrophysics: Stellar collapse and supernovae

    International Nuclear Information System (INIS)

    Lattimer, J.M.; Yahil, A.

    1991-01-01

    The interaction between nuclear theory and some outstanding problems in astrophysics is examined. We are actively researching the astrophysics of gravitational collapse, neutron star birth and neutrino emission, and neutron star cooling, on the one hand, and the nuclear physics of the equation of state of hot, dense matter on the other hand. There is close coupling between nuclear theory and supernova and neutron star phenomenon; some nuclear matter properties might be best delineated by astrophysical considerations. Our research has focused on the neutrinos emitted from supernovae, since they are the only available observables of the internal supernova mechanism. We are modifying our hydrodynamical code to use implicit differencing and to include multi-group neutrino diffusion and general relativity. In parallel, we are extending calculations of core collapse supernovae to long times after collapse by using a hybrid explicit-implicit hydrodynamical code and by using simplified neutrino transport. We hope to establish the existence or non-existence of the so-called long-term supernova mechanism. We are also extending models of the neutrino emission and cooling of neutron stars to include the effects of rotation and the direct Urca process that we recently discovered to be crucial. We have developed a rapid version of the dense matter equation of state for use in hydrodynamic codes that retains essentially all the physics of earlier, more detailed equations of state. This version also has the great advantage that nuclear physics inputs, such as the nuclear incompressibility, symmetry, energy, and specific heat, can be specified

  12. The Hodge conjecture and arithmetic quotients of complex balls

    OpenAIRE

    Bergeron, Nicolas; Millson, John; Moeglin, Colette

    2013-01-01

    Let $S$ be a closed Shimura variety uniformized by the complex $n$-ball. The Hodge conjecture predicts that every Hodge class in $H^{2k} (S, \\Q)$, $k=0, \\ldots, n$, is algebraic. We show that this holds for all degree $k$ away from the neighborhood $]n/3, 2n/3[$ of the middle degree. We also address the Tate conjecture and the generalized form of the Hodge conjecture and extend most of our results to Shimura varieties associated to unitary groups of any signature. The proofs make use of the r...

  13. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

  14. Computational models of stellar collapse and core-collapse supernovae

    International Nuclear Information System (INIS)

    Ott, Christian D; O'Connor, Evan; Schnetter, Erik; Loeffler, Frank; Burrows, Adam; Livne, Eli

    2009-01-01

    Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and provides a scalable AMR approach for 3D fully general-relativistic modeling of stellar collapse, core-collapse supernovae and black hole formation on current and future massively-parallel HPC systems. We show Zelmani's scaling properties to more than 16,000 compute cores and discuss first 3D general-relativistic core-collapse results.

  15. The Efficacy of the clay meat ball as a method of traditional meat ...

    African Journals Online (AJOL)

    Keywords: meat ball, protein, mineral content. This work was carried out to determine the effectiveness of the use of clay meat balls (an African traditional method of preserving meat) in extending the shelf life of meat over a period of months against microbial (bacterial and fungal) spoilage and contamination without ...

  16. Technological Packages Extended To Farmers by Non ...

    African Journals Online (AJOL)

    Global Approaches to Extension Practice: A Journal of Agricultural Extension ... extended to farmers by Non Governmental Organizations in the Niger Delta area of Nigeria. ... Modern snailery was the only identified agro forestry technology extended, ... technologies were the significant soil management practices extended.

  17. On the implementation of the spherical collapse model for dark energy models

    Energy Technology Data Exchange (ETDEWEB)

    Pace, Francesco [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL (United Kingdom); Meyer, Sven; Bartelmann, Matthias, E-mail: francesco.pace@manchester.ac.uk, E-mail: sven.meyer@uni-heidelberg.de, E-mail: bartelmann@uni-heidelberg.de [Zentrum für Astronomie der Universität Heidelberg, Institut für theoretische Astrophysik, Philosophenweg 12, D-69120, Heidelberg (Germany)

    2017-10-01

    In this work we review the theory of the spherical collapse model and critically analyse the aspects of the numerical implementation of its fundamental equations. By extending a recent work by [1], we show how different aspects, such as the initial integration time, the definition of constant infinity and the criterion for the extrapolation method (how close the inverse of the overdensity has to be to zero at the collapse time) can lead to an erroneous estimation (a few per mill error which translates to a few percent in the mass function) of the key quantity in the spherical collapse model: the linear critical overdensity δ{sub c}, which plays a crucial role for the mass function of halos. We provide a better recipe to adopt in designing a code suitable to a generic smooth dark energy model and we compare our numerical results with analytic predictions for the EdS and the ΛCDM models. We further discuss the evolution of δ{sub c} for selected classes of dark energy models as a general test of the robustness of our implementation. We finally outline which modifications need to be taken into account to extend the code to more general classes of models, such as clustering dark energy models and non-minimally coupled models.

  18. On the implementation of the spherical collapse model for dark energy models

    Science.gov (United States)

    Pace, Francesco; Meyer, Sven; Bartelmann, Matthias

    2017-10-01

    In this work we review the theory of the spherical collapse model and critically analyse the aspects of the numerical implementation of its fundamental equations. By extending a recent work by [1], we show how different aspects, such as the initial integration time, the definition of constant infinity and the criterion for the extrapolation method (how close the inverse of the overdensity has to be to zero at the collapse time) can lead to an erroneous estimation (a few per mill error which translates to a few percent in the mass function) of the key quantity in the spherical collapse model: the linear critical overdensity δc, which plays a crucial role for the mass function of halos. We provide a better recipe to adopt in designing a code suitable to a generic smooth dark energy model and we compare our numerical results with analytic predictions for the EdS and the ΛCDM models. We further discuss the evolution of δc for selected classes of dark energy models as a general test of the robustness of our implementation. We finally outline which modifications need to be taken into account to extend the code to more general classes of models, such as clustering dark energy models and non-minimally coupled models.

  19. Types of collapse calderas

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre-Diaz, Gerardo J [Centro de Geociencias, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Queretaro, Qro., 76230 (Mexico)], E-mail: ger@geociencias.unam.mx

    2008-10-01

    Three main types of collapse calderas can be defined, 1) summit caldera: those formed at the top of large volcanoes, 2) classic caldera: semi-circular to irregular-shaped large structures, several km in diameter and related to relatively large-volume pyroclastic products, and 3) graben caldera: explosive volcano-tectonic collapse structures from which large-volume, ignimbrite-forming eruptions occurred through several fissural vents along the graben master faults and the intra-graben block faults. These in turn can collapse at least with three styles: 1) Piston: when the collapse occurs as a single crustal block; 2) Trap-door: when collapse occurs unevenly along one side while the opposite side remains with no collapse; 3) Piece-meal: when collapse occurs as broken pieces of the crust on top of the magma chamber.

  20. How does gravity save or kill Q-balls?

    International Nuclear Information System (INIS)

    Tamaki, Takashi; Sakai, Nobuyuki

    2011-01-01

    We explore stability of gravitating Q-balls with potential V 4 (φ)=(m 2 /2)φ 2 -λφ 4 +(φ 6 /M 2 ) via catastrophe theory, as an extension of our previous work on Q-balls with potential V 3 (φ)=(m 2 /2)φ 2 -μφ 3 +λφ 4 . In flat spacetime Q-balls with V 4 in the thick-wall limit are unstable and there is a minimum charge Q min , where Q-balls with Q min are nonexistent. If we take self-gravity into account, on the other hand, there exist stable Q-balls with arbitrarily small charge, no matter how weak gravity is. That is, gravity saves Q-balls with small charge. We also show how stability of Q-balls changes as gravity becomes strong.

  1. Computational models of stellar collapse and core-collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Ott, Christian D; O' Connor, Evan [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA (United States); Schnetter, Erik; Loeffler, Frank [Center for Computation and Technology, Louisiana State University, Baton Rouge, LA (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ (United States); Livne, Eli, E-mail: cott@tapir.caltech.ed [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)

    2009-07-01

    Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and provides a scalable AMR approach for 3D fully general-relativistic modeling of stellar collapse, core-collapse supernovae and black hole formation on current and future massively-parallel HPC systems. We show Zelmani's scaling properties to more than 16,000 compute cores and discuss first 3D general-relativistic core-collapse results.

  2. Effects of homogeneous geometry models in simulating the fuel balls in HTR-10

    International Nuclear Information System (INIS)

    Wang Mengjen; Liang Jenqhorng; Peir Jinnjer; Chao Dersheng

    2012-01-01

    In this study, the core geometry of HTR-10 was simulated using four different models including: (1) model 1 - an explicit double heterogeneous geometry, (2) model 2 - a mixing of UO 2 kernel and four layers in each TRISO particle into one, (3) model 3 - a mixing of 8,335 TRISO particles and the inner graphite matrix in each fuel ball into one, and (4) model 4 - a mixing of the outer graphite shell, 8,335 TRISO particles, and the inner graphite matrix in each fuel ball into one. The associated initial core computations were performed using the MCNP version 1.51 computer code. The experimental fuel loading height of 123 cm was employed for each model. The results revealed that the multiplication factors ranged from largest to smallest with model 1, model 2, model 3, and model 4. The neutron spectrum in the fuel region of each models varied from the hardest to the softest are model 1, model 2, model 3, and model 4 while the averaged neutron spectrum in fuel ball from hardest to softest are model 4, model 3, model 2, and model 1. In addition, the CPU execution times extended from longest to shortest with model 1, model 2, model 3, and model 4. (author)

  3. Experimental research on ball lightning

    International Nuclear Information System (INIS)

    Ofuruton, H.; Ohtsuki, Y.H.

    1990-01-01

    Experiments on producing ball lightning were made with discharge in flammable gas and/or aerosol. A long lifetime (2 s) ball lightning was observed in 2.7 % ethane and 100 cm 3 cotton fibers, and in 1.5 % methane and 1.9 % ethane

  4. The collapse of interstellar gas clouds

    International Nuclear Information System (INIS)

    McNally, D.; Settle, J.J.

    1980-01-01

    The stability of spherically symmetric free-fall collapse to small radial perturbations is examined for non-uniform clouds. It is concluded that fragmentation of the central region of a collapsing gas cloud is possible if: (a) the density distribution is sufficiently smooth; and (b) the collapse is nearly free fall. Generally, perturbations enjoy only finite amplification during the collapse, and the amplification tends to decrease with increasing distance from the centre of the cloud. Unlimited amplification occurs only for uniform density clouds. Fragmentation is therefore unlikely to result from dynamical instability in the outer parts of a non-uniform cloud. Isothermal clouds are also briefly considered and, while it is argued that an earlier suggestion of their instability to fragmentation is unfounded, no general conclusion on the instability of such clouds could be drawn. (author)

  5. Research on Defects Inspection of Solder Balls Based on Eddy Current Pulsed Thermography

    Directory of Open Access Journals (Sweden)

    Xiuyun Zhou

    2015-10-01

    Full Text Available In order to solve tiny defect detection for solder balls in high-density flip-chip, this paper proposed feasibility study on the effect of detectability as well as classification based on eddy current pulsed thermography (ECPT. Specifically, numerical analysis of 3D finite element inductive heat model is generated to investigate disturbance on the temperature field for different kind of defects such as cracks, voids, etc. The temperature variation between defective and non-defective solder balls is monitored for defects identification and classification. Finally, experimental study is carried on the diameter 1mm tiny solder balls by using ECPT and verify the efficacy of the technique.

  6. Collapsed Dark Matter Structures

    Science.gov (United States)

    Buckley, Matthew R.; DiFranzo, Anthony

    2018-02-01

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  7. Collapsed Dark Matter Structures.

    Science.gov (United States)

    Buckley, Matthew R; DiFranzo, Anthony

    2018-02-02

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  8. Characteristics of capacitance-micro-displacement for model of complex interior surface of the 3D Taiji ball and its applications

    Science.gov (United States)

    Zhu, Ruo-Gu; Jiang, Kun; Qing, Zhao-Bo; Liu, Yue-Hui; Yan, Jun

    2006-11-01

    Taiji image originated from ancient China. It is not only the Taoism emblem but also the ancient graphic presentation sign to everything origin. It either has a too far-reaching impact on traditional culture of China, or is influencing the development of current natural science. On the basis of analyzing the classical philosophic theory of two-dimensional (2-D) Taiji image, we developed it into the model of complex interior surface-three-dimensional (3-D) Taiji ball, and explored its possible applications. Combining modern mathematics and physics knowledge, we have studied on the physical meaning of 3-D Taiji ball, thus the plane change of original Taiji image is developed into space change which is more close to the real world. The change layers are obvious increased notably, and the amount of information included in this model increases correspondingly. We also realized a special paper 3-D Taiji ball whose surface is coved with metal foil by means of laser manufacture. A new experiment set-up for measuring micro displace has been designed and constituted thus the relation between capacitance and micro displacement for the 3-D Taiji ball has performed. Experimental and theoretical analyses are also finished. This models of 3-D Taiji ball for physical characteristics are the first time set up. Experimental data and fitting curves between capacitance and micro displacement for the special paper Taiji ball coved with metal foil are suggested. It is shown that the special Taiji ball has less leakage capacitance or more strengthen electric field than an ordinary half ball capacitance. Finally their potential applied values are explored.

  9. Reversible a-Fe2O3 to Fe3O4 transformation during ball milling

    DEFF Research Database (Denmark)

    Linderoth, Søren; Jiang, Jianzhong; Mørup, Steen

    1997-01-01

    The transformation of hematite to magnetite by high-energy ball milling in a sealed container has been studied by Mossbauer spectroscopy and x-ray diffraction. Mechanisms for this transformation are critically discussed. The dominant mechanism is concluded to be due to bond breaking during the high...... energy ball milling followed by release of the oxygen from the vial. The reverse transformation, magnetite to hematite, is demonstrated to occur by ball milling in air. Mechanisms for this reverse transformation are also put forward....

  10. Friction torque in thrust ball bearings grease lubricated

    Science.gov (United States)

    Ianuş, G.; Dumitraşcu, A. C.; Cârlescu, V.; Olaru, D. N.

    2016-08-01

    The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.

  11. Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals.

    Science.gov (United States)

    Abrahamson, John

    2002-01-15

    The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or man-made discharges. The basic model predicted the important properties of "average" observed ball lightning, and the extension in this paper also covers high-energy examples of ball lightning. Laboratory checks of the theory are described, and predictions given of what conditions are necessary for observing ball lightning in the laboratory. Key requirements of the model are a sheltered region near the strike foot and starting materials which can generate a metal vapour under intensive heating, including soil, wood or a metal structure. The evolution of hydrocarbons (often plastics) along with metal vapour can ensure the local survival of the metal vapour even in an oxidizing atmosphere. Subsequent condensation of this vapour to metallic nanoparticles in networks provides the coherence of a ball structure, which also releases light over an extended time. Also discussed is the passage of ball lightning through a sheet of building material, including glass, and its occasional charring of flesh on close contact.

  12. Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

    Science.gov (United States)

    Fleming, David P.; Poplawski, J. V.

    2002-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

  13. Ball Milling Assisted Solvent and Catalyst Free Synthesis of Benzimidazoles and Their Derivatives.

    Science.gov (United States)

    El-Sayed, Taghreed H; Aboelnaga, Asmaa; Hagar, Mohamed

    2016-08-24

    Benzoic acid and o-phenylenediamine efficiently reacted under the green solvent-free Ball Milling method. Several reaction parameters were investigated such as rotation frequency; milling balls weight and milling time. The optimum reaction condition was milling with 56.6 g weight of balls at 20 Hz frequency for one hour milling time. The study was extended for synthesis of a series of benzimidazol-2-one or benzimidazol-2-thione using different aldehydes; carboxylic acids; urea; thiourea or ammonium thiocyanate with o-phenylenediamine. Moreover; the alkylation of benzimidazolone or benzimidazolthione using ethyl chloroacetate was also studied.

  14. Ball Nut Preload Diagnosis of the Hollow Ball Screw through Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Yi-Cheng Huang

    2018-01-01

    Full Text Available This paper studies the diagnostic results of hollow ball screws with different ball nut preload through the support vector machine (SVM process. The method is testified by considering the use of ball screw pretension and different ball nut preload. SVM was used to discriminate the hollow ball screw preload status through the vibration signals and servo motor current signals. Maximum dynamic preloads of 2%, 4%, and 6% ball screws were predesigned, manufactured, and conducted experimentally. Signal patterns with different preload features are separatedby SVM. The irregularity development of the ball screw driving motion current and rolling balls vibration of the ball screw can be discriminated via SVM based on complexity perception. The experimental results successfully show that the prognostic status of ball nut preload can be envisaged by the proposed methodology. The smart reasoning for the health of the ball screw is available based on classification of SVM. This diagnostic method satisfies the purposes of prognostic effectiveness on knowing the ball nut preload status

  15. Enhanced photocatalytic activity of wool-ball-like TiO2 microspheres on carbon fabric and FTO substrates

    Science.gov (United States)

    Zhang, Yu; Gu, Jian; Zhang, Mengqi

    2018-06-01

    The wool-ball-like TiO2 microspheres on carbon fabric (TiO2-CF) and FTO substrates (TiO2-FTO) have been synthesized by a facile hydrothermal method in alkali environment, using commercial TiO2 (P25) as precursors. The XRD results indicate that the as-prepared TiO2 have good crystallinity. And the SEM images show that the wool-ball-like TiO2 microspheres with a diameter of 2-3 μm are composed of TiO2 nanowires, which have a diameter of 50 nm. The photocatalytic behavior of the wool-ball-like TiO2 microspheres, TiO2-CF and TiO2-FTO under ultraviolet light was investigated by a pseudo first-order kinetic model, using methyl orange (MO) as pollutant. The wool-ball-like TiO2 microspheres obtained a degradation rate constant (Kap) of 6.91×10-3 min-1 . The Kap values of TiO2-FTO and TiO2-CF reach 13.97×10-3 min-1 and 11.80×10-3 min-1, which are 2.0 and 1.7 times higher than that of pristine wool-ball-like TiO2 microspheres due to the "sum effect" between TiO2 and substrates. This study offers a facile hydrothermal method to prepare wool-ball-like TiO2 microspheres on CF and FTO substrates, which will improve the recyclability of phtocatalysts and can be extended to other fields.

  16. Study of soccer ball flight trajectory

    Directory of Open Access Journals (Sweden)

    Javorova Juliana

    2018-01-01

    Full Text Available In this paper the trajectories of a soccer ball for the most important kicks in the football game - a corner kick and a direct free kick are studied. The soccer ball is modelled as an ideal rigid hollow spherical body with six degrees of freedom, which performs a general motion in an immovable air environment with constant parameters. The ball 3D orientation is determined by the three Cardan angles. The aerodynamic forces and moments with which the air environment acts to the ball are taken into account. Two of the most dangerous areas of the football goal are defined. Differential equations which describe the motion of the soccer ball are solved numerically by MatLab-Simulink.

  17. Dynamic Control of Collapse in a Vortex Airy Beam

    Science.gov (United States)

    Chen, Rui-Pin; Chew, Khian-Hooi; He, Sailing

    2013-01-01

    Here we study systematically the self-focusing dynamics and collapse of vortex Airy optical beams in a Kerr medium. The collapse is suppressed compared to a non-vortex Airy beam in a Kerr medium due to the existence of vortex fields. The locations of collapse depend sensitively on the initial power, vortex order, and modulation parameters. The collapse may occur in a position where the initial field is nearly zero, while no collapse appears in the region where the initial field is mainly distributed. Compared with a non-vortex Airy beam, the collapse of a vortex Airy beam can occur at a position away from the area of the initial field distribution. Our study shows the possibility of controlling and manipulating the collapse, especially the precise position of collapse, by purposely choosing appropriate initial power, vortex order or modulation parameters of a vortex Airy beam. PMID:23518858

  18. THE EXTENDED HUBBLE SPACE TELESCOPE SUPERNOVA SURVEY: THE RATE OF CORE COLLAPSE SUPERNOVAE TO z {approx} 1

    Energy Technology Data Exchange (ETDEWEB)

    Dahlen, Tomas; Riess, Adam G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Strolger, Louis-Gregory [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY 42101 (United States); Mattila, Seppo; Kankare, Erkki [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland); Mobasher, Bahram, E-mail: dahlen@stsci.edu [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)

    2012-09-20

    We use a sample of 45 core collapse supernovae detected with the Advanced Camera for Surveys on board the Hubble Space Telescope to derive the core collapse supernova rate in the redshift range 0.1 < z < 1.3. In redshift bins centered on (z) = 0.39, (z) = 0.73, and (z) = 1.11, we find rates of 3.00{sup +1.28}{sub -0.94} {sup +1.04}{sub -0.57}, 7.39{sup +1.86}{sub -1.52} {sup +3.20}{sub -1.60}, and 9.57{sup +3.76}{sub -2.80} {sup +4.96}{sub -2.80}, respectively, given in units of yr{sup -1} Mpc{sup -3} 10{sup -4} h {sup 3}{sub 70}. The rates have been corrected for host galaxy extinction, including supernovae missed in highly dust-enshrouded environments in infrared bright galaxies. The first errors are statistical while the second ones are the estimated systematic errors. We perform a detailed discussion of possible sources of systematic errors and note that these start to dominate over statistical errors at z > 0.5, emphasizing the need to better control the systematic effects. For example, a better understanding of the amount of dust extinction in the host galaxies and knowledge of the supernova luminosity function, in particular the fraction of faint M {approx}> -15 supernovae, is needed to better constrain the rates. When comparing our results with the core collapse supernova rate based on the star formation rate, we find a good agreement, consistent with the supernova rate following the star formation rate, as expected.

  19. How does gravity save or kill Q-balls?

    OpenAIRE

    Tamaki, Takashi; Sakai, Nobuyuki

    2011-01-01

    We explore stability of gravitating Q-balls with potential $V_4(\\phi)={m^2\\over2}\\phi^2-\\lambda\\phi^4+\\frac{\\phi^6}{M^2}$ via catastrophe theory, as an extension of our previous work on Q-balls with potential $V_3(\\phi)={m^2\\over2}\\phi^2-\\mu\\phi^3+\\lambda\\phi^4$. In flat spacetime Q-balls with $V_4$ in the thick-wall limit are unstable and there is a minimum charge $Q_{{\\rm min}}$, where Q-balls with $Q

  20. Having a Ball with Fitness Balls

    Science.gov (United States)

    McNulty, Betty

    2011-01-01

    Fitness programs can be greatly enhanced with the addition of fitness balls. They are a fun, challenging, economical, and safe way to incorporate a cardiovascular, strength, and stretching program for all fitness levels in a physical education setting. The use of these balls has become more popular during the last decade, and their benefits and…

  1. 3D Printing of Ball Grid Arrays

    Science.gov (United States)

    Sinha, Shayandev; Hines, Daniel; Dasgupta, Abhijit; Das, Siddhartha

    Ball grid arrays (BGA) are interconnects between an integrated circuit (IC) and a printed circuit board (PCB), that are used for surface mounting electronic components. Typically, lead free alloys are used to make solder balls which, after a reflow process, establish a mechanical and electrical connection between the IC and the PCB. High temperature processing is required for most of these alloys leading to thermal shock causing damage to ICs. For producing flexible circuits on a polymer substrate, there is a requirement for low temperature processing capabilities (around 150 C) and for reducing strain from mechanical stresses. Additive manufacturing techniques can provide an alternative methodology for fabricating BGAs as a direct replacement for standard solder bumped BGAs. We have developed aerosol jet (AJ) printing methods to fabricate a polymer bumped BGA. As a demonstration of the process developed, a daisy chain test chip was polymer bumped using an AJ printed ultra violet (UV) curable polymer ink that was then coated with an AJ printed silver nanoparticle laden ink as a conducting layer printed over the polymer bump. The structure for the balls were achieved by printing the polymer ink using a specific toolpath coupled with in-situ UV curing of the polymer which provided good control over the shape, resulting in well-formed spherical bumps on the order of 200 um wide by 200 um tall for this initial demonstration. A detailed discussion of the AJ printing method and results from accelerated life-time testing will be presented

  2. 3D GIS spatial operation based on extended Euler operators

    Science.gov (United States)

    Xu, Hongbo; Lu, Guonian; Sheng, Yehua; Zhou, Liangchen; Guo, Fei; Shang, Zuoyan; Wang, Jing

    2008-10-01

    The implementation of 3 dimensions spatial operations, based on certain data structure, has a lack of universality and is not able to treat with non-manifold cases, at present. ISO/DIS 19107 standard just presents the definition of Boolean operators and set operators for topological relationship query, and OGC GeoXACML gives formal definitions for several set functions without implementation detail. Aiming at these problems, based mathematical foundation on cell complex theory, supported by non-manifold data structure and using relevant research in the field of non-manifold geometry modeling for reference, firstly, this paper according to non-manifold Euler-Poincaré formula constructs 6 extended Euler operators and inverse operators to carry out creating, updating and deleting 3D spatial elements, as well as several pairs of supplementary Euler operators to convenient for implementing advanced functions. Secondly, we change topological element operation sequence of Boolean operation and set operation as well as set functions defined in GeoXACML into combination of extended Euler operators, which separates the upper functions and lower data structure. Lastly, we develop underground 3D GIS prototype system, in which practicability and credibility of extended Euler operators faced to 3D GIS presented by this paper are validated.

  3. Ceramic ball grid array package stress analysis

    Science.gov (United States)

    Badri, S. H. B. S.; Aziz, M. H. A.; Ong, N. R.; Sauli, Z.; Alcain, J. B.; Retnasamy, V.

    2017-09-01

    The ball grid array (BGA), a form of chip scale package (CSP), was developed as one of the most advanced surface mount devices, which may be assembled by an ordinary surface ball bumps are used instead of plated nickel and gold (Ni/Au) bumps. Assembly and reliability of the BGA's printed circuit board (PCB), which is soldered by conventional surface mount technology is considered in this study. The Ceramic Ball Grid Array (CBGA) is a rectangular ceramic package or square-shaped that will use the solder ball for external electrical connections instead of leads or wire for connections. The solder balls will be arranged in an array or grid at the bottom of the ceramic package body. In this study, ANSYS software is used to investigate the stress on the package for 2 balls and 4 balls of the CBGA package with the various force range of 1-3 Newton applied to the top of the die, top of the substrate and side of the substrate. The highest maximum stress was analyzed and the maximum equivalent stress was observed on the solder ball and the die. From the simulation result, the CBGA package with less solder balls experience higher stress compared to the package with many solder balls. Therefore, less number of solder ball on the CBGA package results higher stress and critically affect the reliability of the solder balls itself, substrate and die which can lead to the solder crack and also die crack.

  4. Thermodynamics of Non-Topological Solitons

    CERN Document Server

    Laine, Mikko

    1998-01-01

    In theories with low energy supersymmetry breaking, the effective potential for squarks and sleptons has generically nearly flat directions, V(phi) ~ M^4 (log(phi/M))^n. This guarantees the existence of stable non-topological solitons, Q-balls, that carry large baryon number, B >> (M/m_p)^4, where m_p is the proton mass. We study the behaviour of these objects in a high temperature plasma. We show that in an infinitely extended system with a finite density of the baryon charge, the equilibrium state is not homogeneous and contains Q-balls at any temperature. In a system with a finite volume, Q-balls evaporate at a volume dependent temperature. In the cosmological context, we formulate the conditions under which Q-balls, produced in the Early Universe, survive till the present time. Finally, we estimate the baryon to cold dark matter ratio in a cosmological scenario in which Q-balls are responsible for both the net baryon number of the Universe and its dark matter. We find out naturally the correct orders of m...

  5. Scalar field collapse in Gauss-Bonnet gravity

    Science.gov (United States)

    Banerjee, Narayan; Paul, Tanmoy

    2018-02-01

    We consider a "scalar-Einstein-Gauss-Bonnet" theory in four dimension, where the scalar field couples non-minimally with the Gauss-Bonnet (GB) term. This coupling with the scalar field ensures the non-topological character of the GB term. In this scenario, we examine the possibility for collapsing of the scalar field. Our result reveals that such a collapse is possible in the presence of Gauss-Bonnet gravity for suitable choices of parametric regions. The singularity formed as a result of the collapse is found to be a curvature singularity which is hidden from the exterior by an apparent horizon.

  6. Magnetic tension and gravitational collapse

    International Nuclear Information System (INIS)

    Tsagas, Christos G

    2006-01-01

    The gravitational collapse of a magnetized medium is investigated by studying qualitatively the convergence of a timelike family of non-geodesic worldlines in the presence of a magnetic field. Focusing on the field's tension, we illustrate how the winding of the magnetic forcelines due to the fluid's rotation assists the collapse, while shear-like distortions in the distribution of the field's gradients resist contraction. We also show that the relativistic coupling between magnetism and geometry, together with the tension properties of the field, lead to a magneto-curvature stress that opposes the collapse. This tension stress grows stronger with increasing curvature distortion, which means that it could potentially dominate over the gravitational pull of the matter. If this happens, a converging family of non-geodesic worldlines can be prevented from focusing without violating the standard energy conditions

  7. A Computational Study of Re-emission Balls Proposed for the NIF Ignition Symmetry Campaign

    Science.gov (United States)

    Meeker, D. J.; Amendt, P.; Dewald, E.; Edwards, M. J.; Milovich, J.; Suter, L.

    2006-10-01

    Re-emission balls are high-Z spheres used as surrogates for ICF ignition capsules to detect and correct early-time asymmetries of radiation flux at the target. Emission from these balls mimics the incoming flux due to their high albedo, providing a useful symmetry diagnostic. Experiments on Nova by LANL [1] and LLNL used bismuth (Bi) as the surrogate, selected for its high albedo and insensitivity to the fluorescence of the gold hohlraum wall. We are studying the applicability of these capsules to the NIF symmetry campaign as a potential tuning mechanism to achieve the accuracies required for symmetric implosions. We will describe 2-D simulations that predict the emission of the Bi ball as a function of time, frequency, and spatial distribution, as well as quantifying surrogacy of re- emission balls. Using several tuning examples, we will show the resolution expected from this diagnostic. Suggestions for extending this technique to longer times will be discussed as well as describing 3-D effects from diagnostic viewing ports and an opposing hole to eliminate competing wall emission. [1] Delamater, Phys. Rev. E 53, 5240 (1996), Magelssen, Phys. Rev. E 57, 4663 (1998)

  8. Non-adiabatic radiative collapse of a relativistic star under different ...

    Indian Academy of Sciences (India)

    ditions. The collapse of a star filled with a homogeneous perfect fluid is compared with that of a star filled with ... We have examined the collapse of a relativistic star with matter density and fluid pressure decreasing ..... are invoked to extract information about the change in the equation of state of the interior matter of a ...

  9. Multi-stage volcanic island flank collapses with coeval explosive caldera-forming eruptions.

    Science.gov (United States)

    Hunt, James E; Cassidy, Michael; Talling, Peter J

    2018-01-18

    Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small (300 km 3 ), but can also occur in complex multiple stages. Here, we show that multistage retrogressive landslides on Tenerife triggered explosive caldera-forming eruptions, including the Diego Hernandez, Guajara and Ucanca caldera eruptions. Geochemical analyses were performed on volcanic glasses recovered from marine sedimentary deposits, called turbidites, associated with each individual stage of each multistage landslide. These analyses indicate only the lattermost stages of subaerial flank failure contain materials originating from respective coeval explosive eruption, suggesting that initial more voluminous submarine stages of multi-stage flank collapse induce these aforementioned explosive eruption. Furthermore, there are extended time lags identified between the individual stages of multi-stage collapse, and thus an extended time lag between the initial submarine stages of failure and the onset of subsequent explosive eruption. This time lag succeeding landslide-generated static decompression has implications for the response of magmatic systems to un-roofing and poses a significant implication for ocean island volcanism and civil emergency planning.

  10. Hydrogeologic Characterization of the U-3bl Collapse Zone

    International Nuclear Information System (INIS)

    NSTec Geotechnical Services

    2006-01-01

    The U-3bl collapse crater was formed by an underground nuclear test in August 1962. This crater and the adjoining U-3ax crater were subsequently developed and used as a bulk low-level radioactive waste disposal cell (U-3ax/bl), which is part of the Area 3 Radioactive Waste Management Site at the Nevada Test Site (NTS). Various investigations have been conducted to assess the hydrogeologic characteristics and properties in the vicinity of the U-3ax/bl waste disposal cell. This report presents data from one of these investigations, conducted in 1996. Also included in this report is a review of pertinent nuclear testing records, which shows that the testing operations and hydrogeologic setting of the U-3ax/bl site were typical for the period and location of testing. Borehole U-3bl-D2 is a 45-degree-angle hole drilled from the edge of the crater under the waste cell to intercept the U-3bl collapse zone, the disturbed alluvium between the crater (surface collapse sink) and the nuclear test cavity. A casing-advance system with an air percussion hammer was used to drill the borehole, and air was used as the drilling fluid. Properties of the U-3bl crater collapse zone were determined from cores collected within the interval, 42.1 to 96.6 meters (138 to 317 feet) below the ground surface. Selected core samples were analyzed for particle density, particle size, bulk density, water retention, hydraulic conductivity, water content, water potential, chloride, carbonate, stable isotopes, and tritium. Physical and hydraulic properties were typical of alluvial valley sediments at the NTS. No visual evidence of preferential pathways for water transport was observed in the core samples. Soil parameters showed no trends with depth. Volumetric water content values ranged from 0.08 to 0.20 cubic meters per cubic meter, and tended to increase with depth. Water-retention relations were typical for soils of similar texture. Water potentials ranged from -1.9 MegaPascals at a depth of 42

  11. Ball milling of chalcopyrite: Moessbauer spectroscopy and XRD studies

    International Nuclear Information System (INIS)

    Pollak, H.; Fernandes, M.; Levendis, D.; Schonig, L.

    1999-01-01

    The aim of this project is to study the behavior of chalcopyrite under ball milling for extended periods in order to determine how it's decompose or transform. Tests were done with chalcopyrite mixed with iron and zinc with and without surfactant. The use of surfactants has various effects such as avoiding oxidation and clustering of the fine particles. In all case magnetic chalcopyrite is transformed into a paramagnetic component showing a disordered structure, thus revealing that Cu atoms have replaced Fe atoms. In the case of ball milling in air, chalcopyrite is decomposed with the lost of iron, while in milling under surfactants, iron enters into the chalcopyrite structure. (author)

  12. Scalar field collapse in Gauss-Bonnet gravity

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Narayan [Indian Institute of Science Education and Research Kolkata, Department of Physical Sciences, Nadia, West Bengal (India); Paul, Tanmoy [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)

    2018-02-15

    We consider a ''scalar-Einstein-Gauss-Bonnet'' theory in four dimension, where the scalar field couples non-minimally with the Gauss-Bonnet (GB) term. This coupling with the scalar field ensures the non-topological character of the GB term. In this scenario, we examine the possibility for collapsing of the scalar field. Our result reveals that such a collapse is possible in the presence of Gauss-Bonnet gravity for suitable choices of parametric regions. The singularity formed as a result of the collapse is found to be a curvature singularity which is hidden from the exterior by an apparent horizon. (orig.)

  13. The incredible shrinking ball

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Maurice

    2011-12-15

    In the oil and gas industry, the implementation of fracture systems using ball and seat technology helped make multistage fracturing possible. However, frac balls can obstruct later production flow by staying in the well. Baker Hughes Inc. developed a technology to solve this problem: IN-Tallic frac balls. The unique feature of these frac balls is that they are made of an electrolytic metallic nanostructured material which is light and strong and which melts away with salt water or brine through a decomposition process governed by electrochemical reactions controlled by nanoscale coatings. These balls need to be kept away from moisture in order to prevent degradation. This technology is more expensive than traditional frac balls but it prevents the need to mill out obstructions created by the balls. The IN-Tallic frac balls are a new technology which provides operators with peace of mind.

  14. Dark matter gravitinos and baryons via Q-ball decay in the gauge-mediated MSSM

    International Nuclear Information System (INIS)

    Doddato, Francesca; McDonald, John

    2013-01-01

    We show that late Q-ball decay in the MSSM with gauge-mediated SUSY breaking can provide a natural source of non-thermal NLSPs which subsequently decay to gravitino dark matter without violating nucleosynthesis constraints. To show this, we perform a global analysis of Q-ball formation and decay in Affleck-Dine baryogenesis for a d = 6 (u c d c d c ) 2 flat direction of the gauge-mediated MSSM. A general phenomenological potential for the flat-direction is studied and the Q-ball decay properties are obtained as a function of its parameters. The corresponding gravitino mass necessary to account for dark matter is then determined for the case of stau NLSPs. The decay temperature depends on the charge of the Q-balls, which is determined by the fragmentation of the AD condensate. Different fragmentation scenarios are considered, and the final non-thermal NLSP density from Q-ball decay and NLSP annihilation is determined. Particular care is taken to establish that NLSPs from Q-ball decay become homogeneous and non-relativistic prior to annihilation. The gravitino mass necessary for dark matter is naturally consistent with the theoretical gravitino mass in the gauge-mediation model

  15. Reactive-inspired ball-milling synthesis of an ODS steel: study of the influence of ball-milling and annealing

    International Nuclear Information System (INIS)

    Brocq, M.

    2010-10-01

    In the context of the development of new ODS (Oxide Dispersion Strengthened) steels as core materials in future nuclear reactors, we investigated a new process inspired by reactive ball-milling which consists in using YFe 3 andFe 2 O 3 as starting reactants instead of Y 2 O 3 to produce a dispersion of nano-oxides in a steel matrix and the influence of synthesis conditions on the nano-oxide characteristics were studied. For that aim, ODS steels were prepared by ball-milling and then annealed. Multi-scale characterizations were performed after each synthesis step, using notably atom probe tomography and small angle neutron scattering. The process inspired by reactive ball-milling was shown to be efficient for ODS steel synthesis, but it does not modify the nano-oxide characteristics as compared to those of oxides directly incorporated in the matrix by ball-milling. Broadly speaking, the nature of the starting oxygen bearing reactants has no influence on nano-oxide formation. Moreover, we showed that the nucleation of nano-oxides nucleation can start during milling and continues during annealing with a very fast kinetic. The final characteristics of nano-oxides formed in this way can be monitored through ball-milling parameters (intensity, temperature and atmosphere) and annealing parameters (duration and temperature). (author)

  16. Hamiltonian treatment of the gravitational collapse of thin shells

    International Nuclear Information System (INIS)

    Crisostomo, Juan; Olea, Rodrigo

    2004-01-01

    A Hamiltonian treatment of the gravitational collapse of thin shells is presented. The direct integration of the canonical constraints reproduces the standard shell dynamics for a number of known cases. The formalism is applied in detail to three-dimensional spacetime and the properties of the (2+1)-dimensional charged black hole collapse are further elucidated. The procedure is also extended to deal with rotating solutions in three dimensions. The general form of the equations providing the shell dynamics implies the stability of black holes, as they cannot be converted into naked singularities by any shell collapse process

  17. Supermassive dark-matter Q-balls in galactic centers?

    Energy Technology Data Exchange (ETDEWEB)

    Troitsky, Sergey [Institute for Nuclear Research of the Russian Academy of Sciences,60th October Anniversary Prospect 7a, Moscow 117312 (Russian Federation); Moscow Institute for Physics and Technology,Institutskii per. 9, 141700, Dolgoprudny, Moscow Region (Russian Federation)

    2016-11-11

    Though widely accepted, it is not proven that supermassive compact objects (SMCOs) residing in galactic centers are black holes. In particular, the Milky Way’s SMCO can be a giant nontopological soliton, Q-ball, made of a scalar field: this fits perfectly all observational data. Similar but tiny Q-balls produced in the early Universe may constitute, partly or fully, the dark matter. This picture explains in a natural way, why our SMCO has very low accretion rate and why the observed angular size of the corresponding radio source is much smaller than expected. Interactions between dark-matter Q-balls may explain how SMCOs were seeded in galaxies and resolve well-known problems of standard (non-interacting) dark matter.

  18. On longevity of I-ball/oscillon

    Energy Technology Data Exchange (ETDEWEB)

    Mukaida, Kyohei [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Takimoto, Masahiro [Theory Center, KEK,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel); Yamada, Masaki [Institute of Cosmology, Department of Physics and Astronomy, Tufts University,Medford, MA 02155 (United States); Department of Physics, Tohoku University,Sendai, Miyagi 980-8578 (Japan)

    2017-03-23

    We study I-balls/oscillons, which are long-lived, quasi-periodic, and spatially localized solutions in real scalar field theories. Contrary to the case of Q-balls, there is no evident conserved charge that stabilizes the localized configuration. Nevertheless, in many classical numerical simulations, it has been shown that they are extremely long-lived. In this paper, we clarify the reason for the longevity, and show how the exponential separation of time scales emerges dynamically. Those solutions are time-periodic with a typical frequency of a mass scale of a scalar field. This observation implies that they can be understood by the effective theory after integrating out relativistic modes. We find that the resulting effective theory has an approximate global U(1) symmetry reflecting an approximate number conservation in the non-relativistic regime. As a result, the profile of those solutions is obtained via the bounce method, just like Q-balls, as long as the breaking of the U(1) symmetry is small enough. We then discuss the decay processes of the I-ball/oscillon by the breaking of the U(1) symmetry, namely the production of relativistic modes via number violating processes. We show that the imaginary part is exponentially suppressed, which explains the extraordinary longevity of I-ball/oscillon. In addition, we find that there are some attractor behaviors during the evolution of I-ball/oscillon that further enhance the lifetime. The validity of our effective theory is confirmed by classical numerical simulations. Our formalism may also be useful to study condensates of ultra light bosonic dark matter, such as fuzzy dark matter, and axion stars, for instance.

  19. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Golf Ball

    Science.gov (United States)

    1998-01-01

    The Ultra 500 Series golf balls, introduced in 1995 by Wilson Sporting Goods Company, has 500 dimples arranged in a pattern of 60 spherical triangles. The design employs NASA's aerodynamics technology analysis of air loads of the tank and Shuttle orbiter that was performed under the Space Shuttle External Tank program. According to Wilson, this technology provides 'the most symmetrical ball surface available, sustaining initial velocity longer and producing the most stable ball flight for unmatched accuracy and distance.' The dimples are in three sizes, shapes and depths mathematically positioned for the best effect. The selection of dimples and their placement optimizes the interaction of opposing forces of lift and drag. Large dimples reduce air drag, enhance lift, and maintain spin for distance. Small dimples prevent excessive lift that destabilizes the ball flight and the medium size dimples blend the other two.

  1. Collapsing stage of 'bosonic matter'

    International Nuclear Information System (INIS)

    Manoukian, E.B.; Muthaporn, C.; Sirininlakul, S.

    2006-01-01

    We prove rigorously that for 'bosonic matter', if deflation occurs upon collapse as more and more such matter is put together, then for a non-vanishing probability of having the negatively charged particles, with Coulomb interactions, within a sphere of radius R, the latter necessarily cannot decrease faster than N -1/3 for large N, where N denotes the number of the negatively charged particles. This is in clear distinction with matter (i.e., matter with the exclusion principle) which inflates and R necessarily increases not any slower than N 1/3 for large N

  2. 3D visualization of liquefaction-induced dune collapse in the Navajo Sandstone, Utah, USA

    Science.gov (United States)

    Ford, Colby; Nick, Kevin; Bryant, Gerald

    2015-04-01

    The eolian Navajo Sandstone outcrop on the Canyon Overlook Trail in Zion National Park in Southern Utah is dissected by modern erosion in a way which reveals a great deal of the three-dimensional architecture of a major soft-sediment deformation event. The feature is bounded below by a well-developed interdune complex made up of two superimposed carbonate lenses, above by an irregular truncational surface, and incorporates 3 - 10 m of sandstone over an approximately 2 km area. The material above the deformed interval is undeformed cross-bedded sandstone, with crossbeds downlapping onto the surface of truncation. The stratigraphic confinement of deformation and the irregularity of the upper bounding surface suggests a deformation process which created topography, which was in turn covered by the next upwind dune before it could be eroded flat. The deformed material itself is laterally segmented by a stacked succession of shear surfaces, which all strike approximately perpendicular to the paleo-wind direction and dip at decreasing angles in the down paleo-wind direction. These factors point to the collapse of a major dune into the downwind interdune area, likely initiated by liquefaction in the interdune complex. The foundering of the dune's toe into the liquefied area created a powerful lateral stress field which did not extend significantly into the subsurface. The dune collapse process has been used in the past to describe other soft-sediment deformation features in the Navajo Sandstone, but this site provides a wealth of physical details which were not previously associated with dune collapse. Shear surfaces originate in the interdune deposit as slip between laminae, then the cohesive muds provided support as they were thrust upward to angles of up to 50 degrees. The margins of the site also contain important paleoenvironmental indicators. Dinosaur tracks are exposed both at the extreme upwind and downwind margins of the interdune deposit in and slightly above

  3. The correct "ball bearings" data.

    Science.gov (United States)

    Caroni, C

    2002-12-01

    The famous data on fatigue failure times of ball bearings have been quoted incorrectly from Lieblein and Zelen's original paper. The correct data include censored values, as well as non-fatigue failures that must be handled appropriately. They could be described by a mixture of Weibull distributions, corresponding to different modes of failure.

  4. Thermal conduction and gravitational collapse

    International Nuclear Information System (INIS)

    Herrera, L.; Jimenez, J.; Esculpi, M.

    1987-01-01

    A method used to study the evolution of radiating spheres, reported some years ago by Herrera, Jimenez, and Ruggeri, is extended to the case in which thermal conduction within the sphere is taken into account. By means of an explicit example it is shown that heat flow, if present, may play an important role, affecting the final outcome of collapse

  5. Dark matter gravitinos and baryons via Q-ball decay in the gauge-mediated MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Doddato, Francesca; McDonald, John, E-mail: f.doddato@lancaster.ac.uk, E-mail: j.mcdonald@lancaster.ac.uk [Lancaster-Manchester-Sheffield Consortium for Fundamental Physics, Cosmology and Astroparticle Physics Group, Dept. of Physics, University of Lancaster, Lancaster LA1 4YB (United Kingdom)

    2013-07-01

    We show that late Q-ball decay in the MSSM with gauge-mediated SUSY breaking can provide a natural source of non-thermal NLSPs which subsequently decay to gravitino dark matter without violating nucleosynthesis constraints. To show this, we perform a global analysis of Q-ball formation and decay in Affleck-Dine baryogenesis for a d = 6 (u{sup c}d{sup c}d{sup c}){sup 2} flat direction of the gauge-mediated MSSM. A general phenomenological potential for the flat-direction is studied and the Q-ball decay properties are obtained as a function of its parameters. The corresponding gravitino mass necessary to account for dark matter is then determined for the case of stau NLSPs. The decay temperature depends on the charge of the Q-balls, which is determined by the fragmentation of the AD condensate. Different fragmentation scenarios are considered, and the final non-thermal NLSP density from Q-ball decay and NLSP annihilation is determined. Particular care is taken to establish that NLSPs from Q-ball decay become homogeneous and non-relativistic prior to annihilation. The gravitino mass necessary for dark matter is naturally consistent with the theoretical gravitino mass in the gauge-mediation model.

  6. Conceptual design of ball-screw type control element drive mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Ho; Kim, Jong In; Huh, Hyung [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-10-01

    In this report, the design features of ball-screw type CEDM with fine-step movement capability are described. The contents of this report are as follows: -Review of Design Requirements for Ball-screw type CEDM -System Description for Ball-screw type CEDM -Design of Ball Bearing and Ball-screw Assembly -Detail Design of Rotary Step Motor -Detail Design of Angular Position Indicator -Materials. The Ball-screw type CEDM described in this report is to be utilized as the starting point for design development of CEDM for SMART. 11 refs., 43 figs., 3 tabs. (Author)

  7. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  8. Structural and dynamical properties of Yukawa balls

    International Nuclear Information System (INIS)

    Block, D; Kroll, M; Arp, O; Piel, A; Kaeding, S; Ivanov, Y; Melzer, A; Henning, C; Baumgartner, H; Ludwig, P; Bonitz, M

    2007-01-01

    To study the structural and dynamical properties of finite 3D dust clouds (Yukawa balls) new diagnostic tools have been developed. This contribution describes the progress towards 3D diagnostics for measuring the particle positions. It is shown that these diagnostics are capable of investigating the structural and dynamical properties of Yukawa balls and gaining insight into their basic construction principles

  9. Homoclinic phenomena in the gravitational collapse

    International Nuclear Information System (INIS)

    Koiller, J.; Mello Neto, J.R.T. de; Soares, I.D.

    1984-01-01

    A class of Bianchi IX cosmological models is shown to have chaotic gravitational collapse, due to Poincare's homoclinic phenomena. Such models can be programmed so that for any given positive integer N (N=infinity included) the universe undergoes N non-periodic oscillations (each oscillation requiring a long time) before collapsing. For N=infinity the universe undergoes periodic oscillations. (Author) [pt

  10. Plastic collapse load of corroded steel plates

    Indian Academy of Sciences (India)

    Keywords. Corroded steel plate; plastic collapse; FEM; rough surface. ... The main aim of present work is to study plastic collapse load of corroded steel plates with irregular surfaces under tension. Non-linear finite element method ... Department of Ocean Engineering, AmirKabir University of Technology, 15914 Tehran, Iran ...

  11. Flight trajectory of a rotating golf ball with grooves

    Science.gov (United States)

    Baek, Moonheum; Kim, Jooha; Choi, Haecheon

    2014-11-01

    Dimples are known to reduce drag on a sphere by the amount of 50% as compared to a smooth surface. Despite the advantage of reducing drag, dimples deteriorate the putting accuracy owing to their sharp edges. To minimize this putting error but maintain the same flight distance, we have devised a grooved golf ball (called G ball hereafter) for several years. In this study, we modify the shape and pattern of grooves, and investigate the flow characteristics of the G ball by performing wind-tunnel experiments at the Reynolds numbers of 0 . 5 ×105 - 2 . 5 ×105 and the spin ratios (ratio of surface velocity to the free-stream velocity) of 0 - 0.6 that include the real golf-ball velocity and rotational speed. We measure the drag and lift forces on the rotating G ball and compare them with those of a smooth ball and two well-known dimpled balls. The lift-to-drag ratio of the G ball is much higher than that of a smooth ball and is in between those of the two dimpled balls. The trajectories of flying golf balls are computed. The flight distance of G ball is almost the same as that of one dimpled ball but slightly shorter than that of the other dimpled ball. The fluid-dynamic aspects of these differences will be discussed at the talk. Supported by 2011-0028032, 2014M3C1B1033980.

  12. Collapse of Non-Rectangular Channels in a Soft Elastomer

    Science.gov (United States)

    Tepayotl-Ramirez, Daniel; Park, Yong-Lae; Lu, Tong; Majidi, Carmel

    2013-03-01

    We examine the collapse of microchannels in a soft elastomer by treating the sidewalls as in- denters that penetrate the channel base. This approach leads to a closed-form algebraic mapping between applied pressure and cross-sectional deformation that are in strong agreement with ex- perimental measurements and Finite Element Analysis (FEA) simulation. Applications of this new approach to modeling soft microchannel collapse range from lab-on-a-chip microfluidics for pressure-controlled protein filtration to soft-matter pressures sensing. We demonstrate the latter by comparing theoretical predictions with experimental measurements of the pressure-controlled electrical resistance of liquid-phase Gallium alloy microchannels embedded in a soft silicone elas- tomer.

  13. Individual ball possession in soccer.

    Directory of Open Access Journals (Sweden)

    Daniel Link

    Full Text Available This paper describes models for detecting individual and team ball possession in soccer based on position data. The types of ball possession are classified as Individual Ball Possession (IBC, Individual Ball Action (IBA, Individual Ball Control (IBC, Team Ball Possession (TBP, Team Ball Control (TBC und Team Playmaking (TPM according to different starting points and endpoints and the type of ball control involved. The machine learning approach used is able to determine how long the ball spends in the sphere of influence of a player based on the distance between the players and the ball together with their direction of motion, speed and the acceleration of the ball. The degree of ball control exhibited during this phase is classified based on the spatio-temporal configuration of the player controlling the ball, the ball itself and opposing players using a Bayesian network. The evaluation and application of this approach uses data from 60 matches in the German Bundesliga season of 2013/14, including 69,667 IBA intervals. The identification rate was F = .88 for IBA and F = .83 for IBP, and the classification rate for IBC was κ = .67. Match analysis showed the following mean values per match: TBP 56:04 ± 5:12 min, TPM 50:01 ± 7:05 min and TBC 17:49 ± 8:13 min. There were 836 ± 424 IBC intervals per match and their number was significantly reduced by -5.1% from the 1st to 2nd half. The analysis of ball possession at the player level indicates shortest accumulated IBC times for the central forwards (0:49 ± 0:43 min and the longest for goalkeepers (1:38 ± 0:58 min, central defenders (1:38 ± 1:09 min and central midfielders (1:27 ± 1:08 min. The results could improve performance analysis in soccer, help to detect match events automatically, and allow discernment of higher value tactical structures, which is based on individual ball possession.

  14. Effect of ball milling time on the hydrogen storage properties of TiF{sub 3}-doped LiAlH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shu-Sheng [Materials and Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Sun, Li-Xian; Zhang, Yao; Zhang, Jian; Chu, Hai-Liang; Fan, Mei-Qiang; Zhang, Tao [Materials and Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Xu, Fen [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Song, Xiao-Yan [College of Materials Science and Engineering, Key Laboratory of Advanced Functional Materials, Chinese Education Ministry, Beijing University of Technology, Beijing 100124 (China); Grolier, Jean Pierre [Laboratory of Thermodynamics of Solutions and Polymers, Blaise Pascal University, 24 Avenue des Landais, 63177-Aubiere Cedex (France)

    2009-10-15

    In the present work, the catalytic effect of TiF{sub 3} on the dehydrogenation properties of LiAlH{sub 4} has been investigated. Decomposition of LiAlH{sub 4} occurs during ball milling in the presence of 4 mol% TiF{sub 3}. Different ball milling times have been used, from 0.5 h to 18 h. With ball milling time increasing, the crystallite sizes of LiAlH{sub 4} get smaller (from 69 nm to 43 nm) and the dehydrogenation temperature becomes lower (from 80 C to 60 C). Half an hour ball milling makes the initial dehydrogenation temperature of doped LiAlH{sub 4} reduce to 80 C, which is 70 C lower than as-received LiAlH{sub 4}. About 5.0 wt.% H{sub 2} can be released from TiF{sub 3}-doped LiAlH{sub 4} after 18 h ball milling in the range of 60 C-145 C (heating rate 2 C min{sup -1}). TiF{sub 3} probably reacts with LiAlH{sub 4} to form the catalyst, TiAl{sub 3}. The mechanochemical and thermochemical reactions have been clarified. However, the rehydrogenation of LiAlH{sub 4}/Li{sub 3}AlH{sub 6} can not be realized under 95 bar H{sub 2} in the presence of TiF{sub 3} because of their thermodynamic properties. (author)

  15. Nuclear collapse observed during the eruption of Mt. Usu

    International Nuclear Information System (INIS)

    Matsumoto, Taka-aki

    2002-01-01

    Mt. Usu which was located about 70 km southwest from Sapporo in Hokkaido (the north island of Japan) began to erupt on March 31 in 2000. A nuclear emulsion was placed on a foot of Mt. Usu to catch small atomic clusters which were expected to be emitted during the eruption. Curious atomic clusters and their reaction products were successfully observed on surfaces of the nuclear emulsion. By comparing them with similar products which were obtained in previous experiments of discharge and electrolysis, it was concluded that micro Ball Lightning was really emitted during the eruption of Mt. Usu and that explosive reactions by nuclear collapse could have been involved to contribute to energy of the eruption. (author)

  16. EXTENDING NUCLEAR ENERGY TO NON-ELECTRICAL APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    R. Boardman; M. McKellar; D. Ingersoll; Z. Houghton; , R. Bromm; C. Desportes

    2014-09-01

    Electricity represents less than half of all energy consumed in the United States and globally. Although a few commercial nuclear power plants world-wide provide energy to non-electrical applications such as district heating and water desalination, nuclear energy has been largely relegated to base-load electricity production. A new generation of smaller-sized nuclear power plants offers significant promise for extending nuclear energy to many non-electrical applications. The NuScale small modular reactor design is especially well suited for these non-traditional customers due to its small unit size, very robust reactor protection features and a highly flexible and scalable plant design. A series of technical and economic evaluation studies have been conducted to assess the practicality of using a NuScale plant to provide electricity and heat to a variety of non-electrical applications, including water desalination, oil refining, and hydrogen production. The studies serve to highlight the unique design features of the NuScale plant for these applications and provide encouraging conclusions regarding the technical and economic viability of extending clean nuclear energy to a broad range of non-electrical energy consumers.

  17. 3-D collapse of rotating stars to Kerr black holes

    International Nuclear Information System (INIS)

    Baiotti, L; Hawke, I; Montero, P J; Loeffler, F L; Rezzolla, L; Stergioulas, N; Font, J A; Seidel, E

    2005-01-01

    We study gravitational collapse of uniformly rotating neutron stars to Kerr black holes, using a new three-dimensional, fully general relativistic hydrodynamics code, which uses high-resolution shock-capturing techniques and a conformal traceless formulation of the Einstein equations. We investigate the gravitational collapse by carefully studying not only the dynamics of the matter, but also that of the trapped surfaces, i.e. of both the apparent and event horizons formed during the collapse. The use of these surfaces, together with the dynamical horizon framework, allows for a precise measurement of the black-hole mass and spin. The ability to successfully perform these simulations for sufficiently long times relies on excising a region of the computational domain which includes the singularity and is within the apparent horizon. The dynamics of the collapsing matter is strongly influenced by the initial amount of angular momentum in the progenitor star and, for initial models with sufficiently high angular velocities, the collapse can lead to the formation of an unstable disc in differential rotation

  18. Casimir Energies for Isorefractive or Diaphanous Balls

    Directory of Open Access Journals (Sweden)

    Kimball A. Milton

    2018-03-01

    Full Text Available It is known that the Casimir self-energy of a homogeneous dielectric ball is divergent, although a finite self-energy can be extracted through second order in the deviation of the permittivity from the vacuum value. The exception occurs when the speed of light inside the spherical boundary is the same as that outside, so the self-energy of a perfectly conducting spherical shell is finite, as is the energy of a dielectric-diamagnetic sphere with ε μ = 1 , a so-called isorefractive or diaphanous ball. Here we re-examine that example and attempt to extend it to an electromagnetic δ -function sphere, where the electric and magnetic couplings are equal and opposite. Unfortunately, although the energy expression is superficially ultraviolet finite, additional divergences appear that render it difficult to extract a meaningful result in general, but some limited results are presented.

  19. Ball-Contact Injuries in 11 National Collegiate Athletic Association Sports: The Injury Surveillance Program, 2009-2010 Through 2014-2015.

    Science.gov (United States)

    Fraser, Melissa A; Grooms, Dustin R; Guskiewicz, Kevin M; Kerr, Zachary Y

    2017-07-01

      Surveillance data regarding injuries caused by ball contact in collegiate athletes have not been well examined and are mostly limited to discussions of concussions and catastrophic injuries.   To describe the epidemiology of ball-contact injuries in 11 National Collegiate Athletic Association (NCAA) sports during the 2009-2010 through 2014-2015 academic years.   Descriptive epidemiology study.   Convenience sample of NCAA programs in 11 sports (men's football, women's field hockey, women's volleyball, men's baseball, women's softball, men's and women's basketball, men's and women's lacrosse, and men's and women's soccer) during the 2009-2010 through 2014-2015 academic years.   Collegiate student-athletes participating in 11 sports.   Ball-contact-injury rates, proportions, rate ratios, and proportion ratios with 95% confidence intervals were based on data from the NCAA Injury Surveillance Program during the 2009-2010 through 2014-2015 academic years.   During the 2009-2010 through 2014-2015 academic years, 1123 ball-contact injuries were reported, for an overall rate of 3.54/10 000 AEs. The sports with the highest rates were women's softball (8.82/10 000 AEs), women's field hockey (7.71/10 000 AEs), and men's baseball (7.20/10 000 AEs). Most ball-contact injuries were to the hand/wrist (32.7%) and head/face (27.0%) and were diagnosed as contusions (30.5%), sprains (23.1%), and concussions (16.1%). Among sex-comparable sports (ie, baseball/softball, basketball, and soccer), women had a larger proportion of ball-contact injuries diagnosed as concussions than men (injury proportion ratio = 2.33; 95% confidence interval = 1.63, 3.33). More than half (51.0%) of ball-contact injuries were non-time loss (ie, participation-restriction time common severe ball-contact injuries were concussions (n = 18) and finger fractures (n = 10).   Ball-contact-injury rates were the highest in women's softball, women's field hockey, and men's baseball. Although

  20. Two-dimensional collapse calculations of cylindrical clouds

    International Nuclear Information System (INIS)

    Bastien, P.; Mitalas, R.

    1979-01-01

    A two-dimensional hydrodynamic computer code has been extensively modified and expanded to study the collapse of non-rotating interstellar clouds. The physics and the numerical methods involved are discussed. The results are presented and discussed in terms of the Jeans number. The critical Jeans number for collapse of non-rotating cylindrical clouds whose length is the same as their diameter is 1.00. No evidence for fragmentation has been found for these clouds, but fragmentation seems quite likely for more elongated cylindrical clouds. (author)

  1. Comparison of existing plastic collapse load solutions with experimental data for 90° elbows

    International Nuclear Information System (INIS)

    Han, Jae-Jun; Lee, Kuk-Hee; Kim, Nak-Hyun; Kim, Yun-Jae; Jerng, Dong Wook; Budden, Peter J.

    2012-01-01

    This paper compares published experimental plastic collapse loads for 90° elbows with existing closed-form solutions. A total of 46 experimental data are considered, covering pure bending (in-plane closing, in-plane opening and out-of-plane bending) and combined pressure and bending loads. The plastic collapse load solutions considered are from the ASME code, the Ductile Fracture handbook of Zahoor, by Chattopadhyay and co-workers, and by Y.-J. Kim and co-workers. Comparisons with the experimental data shows that the ASME code solution is conservative by a factor of 2 on collapse load for in-plane closing bending, 2.3 for out-of-plane bending, and 3 for in-plane opening bending. The solutions given by Kim and co-workers give the least conservative estimates of plastic collapse loads, although they provide slightly non-conservative estimates for some data. - Highlights: ► We compare published 46 experimental data of plastic collapse loads for 90° elbows with existing four different plastic collapse load solutions. ► We find that the ASME code solution is conservative by a factor of 2–3, depending on the loading mode. ► We find that the solutions given by Kim and co-workers give the least conservative estimates of plastic collapse loads.

  2. Effect of a ball skill intervention on children's ball skills and cognitive functions.

    Science.gov (United States)

    Westendorp, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    2014-02-01

    This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning disorders. Ninety-one children with learning disorders (age 7-11 yr old) were recruited from six classes in a Dutch special-needs primary school. The six classes were assigned randomly either to the intervention or to the control group. The control group received the school's regular physical education lessons. In the intervention group, ball skills were practiced in relative static, simple settings as well as in more dynamic and cognitive demanding settings. Both groups received two 40-min lessons per week. Children's scores on the Test of Gross Motor Development-2 (ball skills), Tower of London (problem solving), Trail Making Test (cognitive flexibility), Dutch Analysis of Individual Word Forms (reading), and the Dutch World in Numbers test (mathematics) at pretest, posttest, and retention test were used to examine intervention effects. The results showed that the intervention group significantly improved their ball skills, whereas the control group did not. No intervention effects were found on the cognitive parameters. However, within the intervention group, a positive relationship (r = 0.41, P = 0.007) was found between the change in ball skill performance and the change in problem solving: the larger children's improvement in ball skills, the larger their improvement in problem solving. The present ball skill intervention is an effective instrument to improve the ball skills of children with learning disorders. Further research is needed to examine the effect of the ball skill intervention on the cognitive parameters in this population.

  3. Easily recycled Bi2O3 photocatalyst coatings prepared via ball milling followed by calcination

    Science.gov (United States)

    Cheng, Lijun; Hu, Xumin; Hao, Liang

    2017-06-01

    Bi2O3 photocatalyst coatings derived from Bi coatings were first prepared by a two-step method, namely ball milling followed by the calcination process. The as-prepared samples were characterized by XRD, SEM, XPS and UV-Vis spectra, respectively. The results showed that monoclinic Bi2O3 coatings were obtained after sintering Bi coatings at 673 or 773 K, while monoclinic and triclinic mixed phase Bi2O3 coatings were obtained at 873 or 973 K. The topographies of the samples were observably different, which varied from flower-like, irregular, polygonal to nanosized particles with the increase in calcination temperature. Photodegradation of malachite green under simulated solar irradiation for 180 min showed that the largest degradation efficiency of 86.2% was achieved over Bi2O3 photocatalyst coatings sintered at 873 K. The Bi2O3 photocatalyst coatings, encapsulated with Al2O3 ball with an average diameter around 1 mm, are quite easily recycled, which provides an alternative visible light-driven photocatalyst suitable for practical water treatment application.

  4. Stimulated leaks found with SmartBall tool

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-05-15

    Pure Technologies has developed a SmartBall leak detection tool which can be used in oil and gas pipelines. This tool contains acoustic sensors which listen for leaks and other problems in pipelines. Pig tracking units are used to track the tool along with receivers positioned on the pipe. With these technologies, SmartBall is able to detect small leaks that conventional methods would not detect and to assess their location accurately. Two runs on a Petrobras pipeline in Brazil highlighted the effectiveness of this technology, detecting three simulated leaks as small as 240mL/min. In addition, this system can give an estimation of the leak rate and traverse non piggable pipelines. Software is then used to analyze data and generate a report giving the size and location of the leaks identified. SmartBall is a technology capable of detecting small leaks and locating them in all sorts of oil and gas pipelines.

  5. HIERARCHICAL GRAVITATIONAL FRAGMENTATION. I. COLLAPSING CORES WITHIN COLLAPSING CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Naranjo-Romero, Raúl; Vázquez-Semadeni, Enrique; Loughnane, Robert M. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3-72, Morelia, Michoacán, 58089, México (Mexico)

    2015-11-20

    We investigate the Hierarchical Gravitational Fragmentation scenario through numerical simulations of the prestellar stages of the collapse of a marginally gravitationally unstable isothermal sphere immersed in a strongly gravitationally unstable, uniform background medium. The core developes a Bonnor–Ebert (BE)-like density profile, while at the time of singularity (the protostar) formation the envelope approaches a singular-isothermal-sphere (SIS)-like r{sup −2} density profile. However, these structures are never hydrostatic. In this case, the central flat region is characterized by an infall speed, while the envelope is characterized by a uniform speed. This implies that the hydrostatic SIS initial condition leading to Shu's classical inside-out solution is not expected to occur, and therefore neither should the inside-out solution. Instead, the solution collapses from the outside-in, naturally explaining the observation of extended infall velocities. The core, defined by the radius at which it merges with the background, has a time-variable mass, and evolves along the locus of the ensemble of observed prestellar cores in a plot of M/M{sub BE} versus M, where M is the core's mass and M{sub BE} is the critical BE mass, spanning the range from the “stable” to the “unstable” regimes, even though it is collapsing at all times. We conclude that the presence of an unstable background allows a core to evolve dynamically from the time when it first appears, even when it resembles a pressure-confined, stable BE-sphere. The core can be thought of as a ram-pressure confined BE-sphere, with an increasing mass due to the accretion from the unstable background.

  6. Self-Gravitating Stellar Collapse: Explicit Geodesics and Path Integration

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishna, Jayashree [Department of Mathematics and Natural Sciences, College of Arts and Sciences, Harris-Stowe State University, St. Louis, MO (United States); Bondarescu, Ruxandra [Department of Physics, University of Zurich, Zurich (Switzerland); Moran, Christine C., E-mail: corbett@tapir.caltech.edu [TAPIR, Department of Theoretical Astrophysics, California Institute of Technology, Pasadena, CA (United States)

    2016-11-25

    We extend the work of Oppenheimer and Synder to model the gravitational collapse of a star to a black hole by including quantum mechanical effects. We first derive closed-form solutions for classical paths followed by a particle on the surface of the collapsing star in Schwarzschild and Kruskal coordinates for space-like, time-like, and light-like geodesics. We next present an application of these paths to model the collapse of ultra-light dark matter particles, which necessitates incorporating quantum effects. To do so we treat a particle on the surface of the star as a wavepacket and integrate over all possible paths taken by the particle. The waveform is computed in Schwarzschild coordinates and found to exhibit an ingoing and an outgoing component, where the former contains the probability of collapse, while the latter contains the probability that the star will disperse. These calculations pave the way for investigating the possibility of quantum collapse that does not lead to black hole formation as well as for exploring the nature of the wavefunction inside r = 2M.

  7. Self-Gravitating Stellar Collapse: Explicit Geodesics and Path Integration

    International Nuclear Information System (INIS)

    Balakrishna, Jayashree; Bondarescu, Ruxandra; Moran, Christine C.

    2016-01-01

    We extend the work of Oppenheimer and Synder to model the gravitational collapse of a star to a black hole by including quantum mechanical effects. We first derive closed-form solutions for classical paths followed by a particle on the surface of the collapsing star in Schwarzschild and Kruskal coordinates for space-like, time-like, and light-like geodesics. We next present an application of these paths to model the collapse of ultra-light dark matter particles, which necessitates incorporating quantum effects. To do so we treat a particle on the surface of the star as a wavepacket and integrate over all possible paths taken by the particle. The waveform is computed in Schwarzschild coordinates and found to exhibit an ingoing and an outgoing component, where the former contains the probability of collapse, while the latter contains the probability that the star will disperse. These calculations pave the way for investigating the possibility of quantum collapse that does not lead to black hole formation as well as for exploring the nature of the wavefunction inside r = 2M.

  8. CT differential diagnosis of fungal ball in paranasal sinus caused by different mycotic pathogenic agents

    International Nuclear Information System (INIS)

    Chen Xiaoli; Wang Zhenchang; Lu Xinxin; Xian Junfang; Li Jing; Geng Jiajing

    2012-01-01

    Objective: To evaluate CT characteristics of fungal ball in paranasal sinus caused by different fungi and to enhance differential diagnosis. Methods: CT results and clinical data of 74 patients with fungal ball arising from the paranasal sinuses proved by histopathology from 2007 to 2009 were analyzed retrospectively. The CT characteristics of fungal ball in paranasal sinus caused by different fungi were compared using χ 2 test with P<0.05 considered statistically significant. Results: Among 74 mycotic pathogenic agents,aspergillus was found in 58 cases (including 36 cases with aspergillus flavus, 15 cases with aspergillus fumigatus and 7 with aspergillus versicolor), the others including 5 cases with penicillium, 6 cases with schizophyllum commune, and 5 cases with scedosporium apiospermum. There were significant differences in the number of sinus involved (single sinus involvement was seen in 29 cases caused by aspergillus group and 2 cases caused by non-aspergillus-group, respectively, with χ 2 =7.245, P=0.007), the incidence of fungus ball in ethmoid sinus [39.7% (23/58) of cases caused by aspergillus group and 81.3% (13/16) of cases caused by non-aspergillus-group, respectively, with χ2=8.685, P=0.003] and calcification (40 of 58 cases caused by aspergillus group and 5 of 16 cases caused by non-aspergillus-group, respectively, with χ 2 =7.485, P=0.006), the location of calcification (26 of 40 cases with central calcification and 14 of 40 cases with peripheral calcification in cases caused by aspergillus group, while all of 5 cases caused by non-aspergillus-group with peripheral calcification, χ 2 =7.697, P=0.006). However, there was no significant difference in the incidence of bilateral lesions (χ 2 =1.002, P=0.317), maxillary sinus involvement (χ 2 =0.020, P=0.888), sphenoidal sinus involvement (χ 2 =0.704, P=0.401), frontal sinus involvement (χ 2 =0.126, P=0.723), bony sclerosis (χ 2 =2.024, P=0.155), lamellar calcification (χ 2 =2.045, P=0

  9. Simulating fullerene ball bearings of ultra-low friction

    International Nuclear Information System (INIS)

    Li Xiaoyan; Yang Wei

    2007-01-01

    We report the direct molecular dynamics simulations for molecular ball bearings composed of fullerene molecules (C 60 and C 20 ) and multi-walled carbon nanotubes. The comparison of friction levels indicates that fullerene ball bearings have extremely low friction (with minimal frictional forces of 5.283 x 10 -7 and 6.768 x 10 -7 nN/atom for C 60 and C 20 bearings) and energy dissipation (lowest dissipation per cycle of 0.013 and 0.016 meV/atom for C 60 and C 20 bearings). A single fullerene inside the ball bearings exhibits various motion statuses of mixed translation and rotation. The influences of the shaft's distortion on the long-ranged potential energy and normal force are discussed. The phonic dissipation mechanism leads to a non-monotonic function between the friction and the load rate for the molecular bearings

  10. Extending nuclear energy to non-electrical applications

    Energy Technology Data Exchange (ETDEWEB)

    Ingersoll, D.; Houghton, Z. [NuScale Power, LLC, Corvallis, Oregon (United States); Bromm, R. [Fluor Corp., Greenville, SC (United States); Desportes, C. [Aquatech International, Canonsburg, PA (United States); McKellar, M.; Boardman, R. [Idaho National Laboratory, Idaho Falls, ID (United States)

    2014-07-01

    Electricity represents less than half of all energy consumed in the United States and globally. Although a few commercial nuclear power plants world-wide provide energy to non-electrical applications such as district heating and water desalination, nuclear energy has been largely relegated to base-load electricity production. A new generation of smaller-sized nuclear power plants offers significant promise for extending nuclear energy to many non-electrical applications. The NuScale small modular reactor design is especially well suited for these nontraditional customers due to its small unit size, very robust reactor protection features and a highly flexible and scalable plant design. A series of technical and economic evaluation studies have been conducted to assess the practicality of using a NuScale plant to provide electricity and heat to a variety of non-electrical applications, including water desalination, oil refining, and hydrogen production. The studies serve to highlight the unique design features of the NuScale plant for these applications and provide encouraging conclusions regarding the technical and economic viability of extending clean nuclear energy to a broad range of non-electrical energy consumers. (author)

  11. EFFECT OF CUP AND BALL TYPES ON MECHANO-CHEMICAL SYNTHES IS OF Al2O3–TiC NANOCOMPOSITE POWDER

    Directory of Open Access Journals (Sweden)

    M. Zakeri

    2012-07-01

    Full Text Available Al2O3–TiC nanocomposite powder was successfully synthesized by ball milling TiO2, Al and graphite powders. Effects of cup and ball type, milling time and annealing were investigated. XRD was used to characterize milled and annealed powders. The morphological and microstructural evolutions were studied by SEM and TEM. Results showed that the formation of this composite begins after 20 h and completes after 35 h of milling with stainless steel cup and balls. In contrast, there is no reaction during milling (up to 80 h with ZrO2 cup and balls. Fe and ZrO2 were the major impurities introduced during milling with stainless steel and ZrO2 cups, respectively. The Fe impurity was removed by leaching in 3HCl·HNO3 solution for 4 days. Mean grain size less than 7 nm was achieved at the end of milling. In spite of grain growth, this composite maintained its nanocrystalline nature after annealing at 1000°C.

  12. Evaluation of Dogs with Border Collie Collapse, Including Response to Two Standardized Strenuous Exercise Protocols.

    Science.gov (United States)

    Taylor, Susan; Shmon, Cindy; Su, Lillian; Epp, Tasha; Minor, Katie; Mickelson, James; Patterson, Edward; Shelton, G Diane

    2016-01-01

    Clinical and metabolic variables were evaluated in 13 dogs with border collie collapse (BCC) before, during, and following completion of standardized strenuous exercise protocols. Six dogs participated in a ball-retrieving protocol, and seven dogs participated in a sheep-herding protocol. Findings were compared with 16 normal border collies participating in the same exercise protocols (11 retrieving, five herding). Twelve dogs with BCC developed abnormal mentation and/or an abnormal gait during evaluation. All dogs had post-exercise elevations in rectal temperature, pulse rate, arterial blood pH, PaO2, and lactate, and decreased PaCO2 and bicarbonate, as expected with strenuous exercise, but there were no significant differences between BCC dogs and normal dogs. Electrocardiography demonstrated sinus tachycardia in all dogs following exercise. Needle electromyography was normal, and evaluation of muscle biopsy cryosections using a standard panel of histochemical stains and reactions did not reveal a reason for collapse in 10 dogs with BCC in which these tests were performed. Genetic testing excluded the dynamin-1 related exercise-induced collapse mutation and the V547A malignant hyperthermia mutation as the cause of BCC. Common reasons for exercise intolerance were eliminated. Although a genetic basis is suspected, the cause of collapse in BCC was not determined.

  13. Evaluation of possible head injuries ensuing a cricket ball impact.

    Science.gov (United States)

    Mohotti, Damith; Fernando, P L N; Zaghloul, Amir

    2018-05-01

    The aim of this research is to study the behaviour of a human head during the event of an impact of a cricket ball. While many recent incidents were reported in relation to head injuries caused by the impact of cricket balls, there is no clear information available in the published literature about the possible threat levels and the protection level of the current protective equipment. This research investigates the effects of an impact of a cricket ball on a human head and the level of protection offered by the existing standard cricket helmet. An experimental program was carried out to measure the localised pressure caused by the impact of standard cricket balls. The balls were directed at a speed of 110 km/h on a 3D printed head model, with and without a standard cricket helmet. Numerical simulations were carried out using advanced finite element package LS-DYNA to validate the experimental results. The experimental and numerical results showed approximately a 60% reduction in the pressure on the head model when the helmet was used. Both frontal and side impact resulted in head acceleration values in the range of 225-250 g at a ball speed of 110 km/h. There was a 36% reduction observed in the peak acceleration of the brain when wearing a helmet. Furthermore, numerical simulations showed a 67% reduction in the force on the skull and a 95% reduction in the skull internal energy when introducing the helmet. (1) Upon impact, high localised pressure could cause concussion for a player without helmet. (2) When a helmet was used, the acceleration of the brain observed in the numerical results was at non-critical levels according to existing standards. (3) A significant increase in the threat levels was observed for a player without helmet, based on force, pressure, acceleration and energy criteria, which resulted in recommending the compulsory use of the cricket helmet. (4) Numerical results showed a good correlation with experimental results and hence, the

  14. Numerical study of Q-ball formation in gravity mediation

    International Nuclear Information System (INIS)

    Hiramatsu, Takashi; Kawasaki, Masahiro; Takahashi, Fuminobu

    2010-01-01

    We study Q-ball formation in the expanding universe on 1D, 2D and 3D lattice simulations. We obtain detailed Q-ball charge distributions, and find that the distribution is peaked at Q 3D peak ≅ 1.9 × 10 −2 (|Φ in |/m) 2 , which is greater than the existing result by about 60%. Based on the numerical simulations, we discuss how the Q-ball formation proceeds. Also we make a comment on possible deviation of the charge distributions from what was conjectured in the past

  15. A Plastic Design Method for RC Moment Frame Buildings against Progressive Collapse

    Directory of Open Access Journals (Sweden)

    Hadi Faghihmaleki

    2017-04-01

    Full Text Available In this study, progressive collapse potential of generic 3-, 8- and 12-storey RC moment frame buildings designed based on IBC-2006 code was investigated by performing non-linear static and dynamic analyses. It was observed that the model structures had high potential for progressive collapse when the second floor column was suddenly removed. Then, the size of beams required to satisfy the failure criteria for progressive collapse was obtained by using the virtual work method; i.e., using the equilibrium of the external work done by gravity load due to loss of a column and the internal work done by plastic rotation of beams. According to the nonlinear dynamic analysis results, the model structures designed only for normal load turned out to have strong potential for progressive collapse whereas the structures designed by plastic design concept for progressive collapse satisfied the failure criterion recommended by the GSA code. 

  16. Synthesis of Ni3Ta, Ni2Ta and NiTa by high-energy ball milling and subsequent heat treatment

    International Nuclear Information System (INIS)

    Benites, H.S.N.; Silva, B.P da; Ramos, A.S.; Silva, A.A.A.P.; Coelho, G.C.; Lima, B.B. de

    2014-01-01

    The tantalum has relevance for the development of multicomponent Ni-based superalloys which are hardened by solid solution and precipitation mechanisms. Master alloys are normally used in the production step in order to produce refractory metals and alloys. The present work reports on the synthesis of Ni_3Ta, Ni_2Ta and NiTa by high-energy ball milling and subsequent heat treatment. The elemental Ni-25Ta, Ni-33Ta and Ni-50Ta (at.-%) powder mixtures were ball milled under Ar atmosphere using stainless steel balls and vials, 300 rpm and a ball-to-powder weight ratio of 10:1. Following, the as-milled samples were uniaxially compacted and heat-treated at 1100 deg C for 4h under Ar atmosphere. The characterization of as-milled and heat-treated samples was conducted by means of X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. A large amount of Ni_3Ta, Ni_2Ta and NiTa was formed in the mechanically alloyed heat-treated Ni-25Ta, Ni-33Ta and Ni-50Ta alloys. (author)

  17. Collapse of triangular channels in a soft elastomer

    Science.gov (United States)

    Tepáyotl-Ramírez, Daniel; Lu, Tong; Park, Yong-Lae; Majidi, Carmel

    2013-01-01

    We extend classical solutions in contact mechanics to examine the collapse of channels in a soft elastomer. These channels have triangular cross-section and collapse when pressure is applied to the surrounding elastomer. Treating the walls of the channel as indenters that penetrate the channel base, we derive an algebraic mapping between pressure and cross-sectional area. These theoretical predictions are in strong agreement with results that we obtain through finite element analysis and experimental measurements. This is accomplished without data fitting and suggests that the theoretical approach may be generalized to a broad range of cross-sectional geometries in soft microfluidics.

  18. Collapsing dynamics of attractive Bose-Einstein condensates

    DEFF Research Database (Denmark)

    Bergé, L.; Juul Rasmussen, J.

    2002-01-01

    The self-similar collapse of 3D and quasi-2D atom condensates with negative scattering length is examined. 3D condensates are shown to blow up following the scenario of weak collapse, for which 3-body recombination weakly dissipates the atoms. In contrast, 2D condensates undergo a strong collapse......, that absorbs a significant amount of particles. (C) 2002 Elsevier Science B.V. All rights reserved....

  19. The bowling balls

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    10 November 1972: CERN’s Bent Stumpe places an order for 12 bowling balls for a total cost of 95 US dollars. Although not evident at first sight, he is buying the heart of some of the first tracking devices to be used in the SPS control room. Today, Bent Stumpe’s device would be called a desktop mouse…   The first order for 4 bowling balls later changed to 12 balls. The bowling balls became the heart of Bent Stumpe's mouse. Almost 40 years ago, the web, Wikipedia and Google did not exist and it was much more difficult to know whether other people in other parts of the world or even in the same laboratory were facing the same problems or developing the same tools. At that time, Bent Stumpe was an electronics engineer, newly recruited to work on developments for the SPS Central Control room. One of the things his supervisor asked him to build as soon as possible was a device to control a pointer on a screen, also called a tracker ball. The heart of the device was the...

  20. Four tails problems for dynamical collapse theories

    Science.gov (United States)

    McQueen, Kelvin J.

    2015-02-01

    The primary quantum mechanical equation of motion entails that measurements typically do not have determinate outcomes, but result in superpositions of all possible outcomes. Dynamical collapse theories (e.g. GRW) supplement this equation with a stochastic Gaussian collapse function, intended to collapse the superposition of outcomes into one outcome. But the Gaussian collapses are imperfect in a way that leaves the superpositions intact. This is the tails problem. There are several ways of making this problem more precise. But many authors dismiss the problem without considering the more severe formulations. Here I distinguish four distinct tails problems. The first (bare tails problem) and second (structured tails problem) exist in the literature. I argue that while the first is a pseudo-problem, the second has not been adequately addressed. The third (multiverse tails problem) reformulates the second to account for recently discovered dynamical consequences of collapse. Finally the fourth (tails problem dilemma) shows that solving the third by replacing the Gaussian with a non-Gaussian collapse function introduces new conflict with relativity theory.

  1. The spinning ball spiral

    International Nuclear Information System (INIS)

    Dupeux, Guillaume; Le Goff, Anne; Quere, David; Clanet, Christophe

    2010-01-01

    We discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance L where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports.

  2. Non-colliding Brownian Motions and the Extended Tacnode Process

    Science.gov (United States)

    Johansson, Kurt

    2013-04-01

    We consider non-colliding Brownian motions with two starting points and two endpoints. The points are chosen so that the two groups of Brownian motions just touch each other, a situation that is referred to as a tacnode. The extended kernel for the determinantal point process at the tacnode point is computed using new methods and given in a different form from that obtained for a single time in previous work by Delvaux, Kuijlaars and Zhang. The form of the extended kernel is also different from that obtained for the extended tacnode kernel in another model by Adler, Ferrari and van Moerbeke. We also obtain the correlation kernel for a finite number of non-colliding Brownian motions starting at two points and ending at arbitrary points.

  3. HYDROGEOLOGIC CHARACTERIZATION OF THE U-3bl COLLAPSE ZONE

    International Nuclear Information System (INIS)

    Bechtel Nevada and National Security Technologies, LLC

    2006-01-01

    The U-3bl collapse crater was formed by an underground nuclear test in August 1962. This crater and the adjoining U-3ax crater were subsequently developed and used as a bulk low-level radioactive waste disposal cell (U-3ax/bl), which is part of the Area 3 Radioactive Waste Management Site at the Nevada Test Site (NTS). Various investigations have been conducted to assess the hydrogeologic characteristics and properties in the vicinity of the U-3ax/bl waste disposal cell. This report presents data from one of these investigations, conducted in 1996. Also included in this report is a review of pertinent nuclear testing records, which shows that the testing operations and hydrogeologic setting of the U-3ax/bl site were typical for the period and location of testing

  4. Inertial collapse of bubble pairs near a solid surface

    Science.gov (United States)

    Alahyari Beig, Shahaboddin; Johnsen, Eric

    2017-11-01

    Cavitation occurs in a variety of applications ranging from naval structures to biomedical ultrasound. One important consequence is structural damage to neighboring surfaces following repeated inertial collapse of vapor bubbles. Although the mechanical loading produced by the collapse of a single bubble has been widely investigated, less is known about the detailed dynamics of the collapse of multiple bubbles. In such a problem, the bubble-bubble interactions typically affect the dynamics, e.g., by increasing the non-sphericity of the bubbles and amplifying/hindering the collapse intensity depending on the flow parameters. Here, we quantify the effects of bubble-bubble interactions on the bubble dynamics, as well as the pressures/temperatures produced by the collapse of a pair of gas bubbles near a rigid surface. We perform high-resolution simulations of this problem by solving the three-dimensional compressible Navier-Stokes equations for gas/liquid flows. The results are used to investigate the non-spherical bubble dynamics and characterize the pressure and temperature fields based on the relevant parameters entering the problem: stand-off distance, geometrical configuration (angle, relative size, distance), collapse strength. This research was supported in part by ONR Grant N00014-12-1-0751 and NSF Grant CBET 1253157.

  5. Extended Galilean symmetries of non-relativistic strings

    Energy Technology Data Exchange (ETDEWEB)

    Batlle, Carles [Departament de Matemàtiques and IOC, Universitat Politècnica de Catalunya, EPSEVG,Av. V. Balaguer 1, E-08808 Vilanova i la Geltrú (Spain); Gomis, Joaquim; Not, Daniel [Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos (ICCUB),Universitat de Barcelona,Martí i Franquès 1, E-08028 Barcelona (Spain)

    2017-02-09

    We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.

  6. Poisson structures for reduced non-holonomic systems

    International Nuclear Information System (INIS)

    Ramos, Arturo

    2004-01-01

    Borisov, Mamaev and Kilin have recently found certain Poisson structures with respect to which the reduced and rescaled systems of certain non-holonomic problems, involving rolling bodies without slipping, become Hamiltonian, the Hamiltonian function being the reduced energy. We study further the algebraic origin of these Poisson structures, showing that they are of rank 2 and therefore the mentioned rescaling is not necessary. We show that they are determined, up to a non-vanishing factor function, by the existence of a system of first-order differential equations providing two integrals of motion. We generalize the form of the Poisson structures and extend their domain of definition. We apply the theory to the rolling disc, the Routh's sphere, the ball rolling on a surface of revolution, and its special case of a ball rolling inside a cylinder

  7. Direct collapse to supermassive black hole seeds: comparing the AMR and SPH approaches.

    Science.gov (United States)

    Luo, Yang; Nagamine, Kentaro; Shlosman, Isaac

    2016-07-01

    We provide detailed comparison between the adaptive mesh refinement (AMR) code enzo-2.4 and the smoothed particle hydrodynamics (SPH)/ N -body code gadget-3 in the context of isolated or cosmological direct baryonic collapse within dark matter (DM) haloes to form supermassive black holes. Gas flow is examined by following evolution of basic parameters of accretion flows. Both codes show an overall agreement in the general features of the collapse; however, many subtle differences exist. For isolated models, the codes increase their spatial and mass resolutions at different pace, which leads to substantially earlier collapse in SPH than in AMR cases due to higher gravitational resolution in gadget-3. In cosmological runs, the AMR develops a slightly higher baryonic resolution than SPH during halo growth via cold accretion permeated by mergers. Still, both codes agree in the build-up of DM and baryonic structures. However, with the onset of collapse, this difference in mass and spatial resolution is amplified, so evolution of SPH models begins to lag behind. Such a delay can have effect on formation/destruction rate of H 2 due to UV background, and on basic properties of host haloes. Finally, isolated non-cosmological models in spinning haloes, with spin parameter λ ∼ 0.01-0.07, show delayed collapse for greater λ, but pace of this increase is faster for AMR. Within our simulation set-up, gadget-3 requires significantly larger computational resources than enzo-2.4 during collapse, and needs similar resources, during the pre-collapse, cosmological structure formation phase. Yet it benefits from substantially higher gravitational force and hydrodynamic resolutions, except at the end of collapse.

  8. Formation and stabilization of multiple ball-like flames at Earth gravity

    KAUST Repository

    Zhou, Zhen

    2018-03-20

    Near-limit low-Lewis-number premixed flame behavior is studied experimentally and numerically for flames of H–CH–air mixtures that are located in a 55 mm diameter tube and below a perforated plate in a downward mixture flow. A combustion regime diagram is experimentally identified in terms of equivalence ratio and ratio of H to CH (variation of fuel Lewis number). Planar flames, cell-like flames, distorted cap-like flames, and arrays of ball-like flames are progressively observed in the experiments as the equivalence ratio is decreased. The experimentally observed ball-like lean limit flames experience chaotic motion, which is accompanied by sporadic events of flame splitting and extinction, while the total number of simultaneously burning flamelets remains approximately the same. In separate experiments, the multiple ball-like lean limit flames are stabilized by creating a slightly non-uniform mixture flow field. The CH* chemiluminescence distributions of the lean limit flames are recorded, showing that the ball-like lean limit flame front becomes more uniform in intensity and its shape approaches a spherical one with the increase of H content in the fuel. Numerical simulations are performed for single representative flames of the array of stabilized flamelets observed in the experiments. The simulated ball-like lean limit flame is further contrasted with the single ball-like flame that forms in a narrow tube (13.5 mm inner diameter) with an iso-thermal wall. The numerical results show that the ball-like lean limit flames present in the array of ball-like flames are more affected by the buoyancy-induced recirculation zone, compared with that in the narrow tube, revealing why the shape of the ball-like flame in the array deviates more from a spherical one. All in all, the wall confinement is not crucial for the formation of ball-like flames at terrestrial gravity.

  9. Failure analysis of the ball bearings of dental air turbine handpieces.

    Science.gov (United States)

    Wei, M; Dyson, J E; Darvell, B W

    2013-12-01

    The aim of this study was to identify the nature and causes of deterioration and failure in dental handpiece ball bearings and thus provide guidance for clinical handling for service longevity. The bearings of 36 turbine assemblies were dismantled for visual inspection, documented using a digital camera, and examined using scanning electron microscopy, as appropriate. For the metal parts of the ball bearing assembly, defects observed were mainly wear arising from the running load and corrosion. This was in the form of scratches and discoloured circumferential bands on the balls, and dull or worn surfaces extending around the circumference of the raceways. Cage damage including cracking, fracture, surface rubbing and distortion occurred, in varying degrees, in every failed turbine. Dental ball bearing failure modes have been identified. Cumulative effects of damage from corrosion and mechanical factors lead to handpiece deterioration. The cage was found to be very vulnerable to damage, and this may be the key limitation on bearing lifetime. Autoclaving may contribute to that, as it does to corrosion in the absence of adequate lubrication, but this seems to be minor in comparison to the effects of abuse. There is no justification for failing to observe usage and sterilization instructions. © 2013 Australian Dental Association.

  10. Electron capture and stellar collapse

    International Nuclear Information System (INIS)

    Chung, K.C.

    1979-01-01

    In order, to investigate the function of electron capture in the phenomenon of pre-supernovae gravitacional collapse, an hydrodynamic caculation was carried out, coupling capture, decay and nuclear reaction equation system. A star simplified model (homogeneous model) was adopted using fermi ideal gas approximation for tthe sea of free electrons and neutrons. The non simplified treatment from quasi-static evolution to collapse is presented. The capture and beta decay rates, as wellas neutron delayed emission, were calculated by beta decay crude theory, while the other reaction rates were determined by usual theories. The preliminary results are presented. (M.C.K.) [pt

  11. CFD Analysis of Swing of Cricket Ball and Trajectory Prediction

    Science.gov (United States)

    G, Jithin; Tom, Josin; Ruishikesh, Kamat; Jose, Jyothish; Kumar, Sanjay

    2013-11-01

    This work aims to understand the aerodynamics associated with the flight and swing of a cricket ball and predict its flight trajectory over the course of the game: at start (smooth ball) and as the game progresses (rough ball). Asymmetric airflow over the ball due to seam orientation and surface roughness can cause flight deviation (swing). The values of Drag, Lift and Side forces which are crucial for determining the trajectory of the ball were found with the help of FLUENT using the standard K- ɛ model. Analysis was done to study how the ball velocity, spin imparted to be ball and the tilt of the seam affects the movement of the ball through air. The governing force balance equations in 3 dimensions in combination a MATLAB code which used Heun's method was used for obtaining the trajectory of the ball. The conditions for the conventional swing and reverse swing to occur were deduced from the analysis and found to be in alignment with the real life situation. Critical seam angle for maximum swing and transition speed for normal to reverse swing were found out. The obtained trajectories were compared to real life hawk eye trajectories for validation. The analysis results were in good agreement with the real life situation.

  12. LHC gets the ball rolling

    CERN Multimedia

    2007-01-01

    A technique involving a small ball with a transmitter embedded inside it has been successfully tested in Sector 7-8. The ball is sent through the LHC beam pipes to check the LHC interconnections. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI). During the tests the ball is inserted very carefully into the vacuum chamber.A game of ping-pong at the LHC? On 13 September a rather unusual test was carried out in Sector 7-8 of the accelerator. A ball just a bit smaller than a ping-pong ball was carefully introduced into one of the accelerator’s two vacuum pipes, where it travelled 800 metres in the space of a few mi...

  13. Biaxial testing for nuclear grade graphite by ball on three balls assessment

    International Nuclear Information System (INIS)

    Mohd Reusmaazran Yusof; Yusof Abdullah

    2012-01-01

    Nuclear grade (high-purity) graphite for fuel element and moderator material in Advanced Gas Cooling Reactors (AGR) displays large scatter in strength and a non-linear stress-strain response from the damage accumulation. These responses can be characterized as quasi-brittle behaviour. Current assessments of fracture in core graphite components are based on the linear elastic approximation and thus represent a major assumption. The quasi-brittle behaviour gives challenge to assess the real nuclear graphite component. The selected test method would help to bridge the gap between microscale to macro-scale in real reactor component. The small scale tests presented here can contribute some statistical data to manifests the failure in real component. The evaluation and choice of different solution design of biaxial test will be discussed in this paper. The ball on-three ball test method was used for assessment test follows by numerous of analytical method. The results shown that biaxial strength of the EY9 grade graphite depends on the method used for evaluation. Some of the analytical methods use to calculate biaxial strength were found not to be valid and therefore should not be used to assess the mechanical properties of nuclear graphite. (author)

  14. Gas-discharge particle detector with ball-tipped anodes

    International Nuclear Information System (INIS)

    Travkin, V.I.; Khazins, D.M.

    1987-01-01

    A new gas-discharge particle detector, whose anode is a set of balls 2mm in diameter is investigated. The chamber is blowing down by the argon-methane-methylal gas mixture with the ratio 3:1:1. The detector operates in the self-quenching streamer mode, has high efficiency and a wide counting characteristic plateau. The maximum counting rate of particles at one ball is ∼ 2.5x10 4 s -1 . The ball-tipped anodes allow making reliable complex-shaped detectors. Two-coordinate detection of multiparticle events can be naturally organized in detectors like that

  15. Physical and Tribological Properties of Nitrided AISI 316 Stainless Steel Balls

    Directory of Open Access Journals (Sweden)

    Yang Shicai

    2016-01-01

    Full Text Available AISI 316 austenitic stainless steel balls (diameters 5.0 and 12.0 mm, typical hardness 250 HV0.3 and flat samples (20×20×2.0 mm were nitrided by a pulsed glow discharge Ar/N2 plasma. Hardness of the ball surfaces was analysed using Vickers indentation. Thermal stability of the nitrided balls (diameter 12.0 mm was studied using a furnace to heat them in air for 8 hours at temperatures up to 700.0°C and then, after cooling to room temperature, the surface hardness of the heated balls was re-measured. Scanning electron microscopy and X-ray diffraction were used to study the microstructures, composition and phase formation of the nitrided sublayers. Unlubricated pin-on-disc wear testing was used to evaluate the wear resistance of nitrided stainless steel balls (5.0 mm diameter and the results were compared with similar testing on hardened Cr-Steel balls (5 mm diameter with hardness of about 650 HV0.3. All the test results indicated that the nitrided AISI 316 austenitic stainless steel balls have advantages over the hardened Cr-Steel balls in terms of retaining high hardness after heat treatment and high resistance to sliding wear at room temperature under higher counterpart stress. These properties are expected to be beneficial for wide range of bearing applications.

  16. New Q-ball solutions in gauge-mediation, Affleck-Dine baryogenesis and gravitino dark matter

    International Nuclear Information System (INIS)

    Doddato, Francesca; McDonald, John

    2012-01-01

    Affleck-Dine (AD) baryogenesis along a d = 6 flat direction in gauge-mediated supersymmetry-breaking (GMSB) models can produce unstable Q-balls which naturally have field strength similar to the messenger scale. In this case a new kind of Q-ball is formed, intermediate between the gravity-mediated and gauge-mediated types. We study in detail these new Q-ball solutions, showing how their properties interpolate between standard gravity-mediated and gauge-mediated Q-balls as the AD field becomes larger than the messenger scale. It is shown that E/Q for the Q-balls can be greater than the nucleon mass but less than the MSSM-LSP mass, leading to Q-ball decay primarily to Standard Model fermions. More significantly, if E/Q is greater than the MSSM-LSP mass, decaying Q-balls can provide a natural source of non-thermal MSSM-LSPs, which can subsequently decay to gravitino dark matter without violating nucleosynthesis constraints. The model therefore provides a minimal scenario for baryogenesis and gravitino dark matter in the gauge-mediated MSSM, requiring no new fields

  17. Two Balls' Collision of Mass Ratio 3:1

    Science.gov (United States)

    Ogawara, Yasuo; Hull, Michael M.

    2018-01-01

    Students will sometimes ask why momentum and kinetic energy concepts are both necessary. When physics teachers demonstrate situations that require both an understanding of kinetic energy and momentum, a favorite is Newton's cradle, or a comparable demonstration of two balls of equal mass hitting each other. However, in addition to the case of two…

  18. On the Kalman Filter error covariance collapse into the unstable subspace

    Directory of Open Access Journals (Sweden)

    A. Trevisan

    2011-03-01

    Full Text Available When the Extended Kalman Filter is applied to a chaotic system, the rank of the error covariance matrices, after a sufficiently large number of iterations, reduces to N+ + N0 where N+ and N0 are the number of positive and null Lyapunov exponents. This is due to the collapse into the unstable and neutral tangent subspace of the solution of the full Extended Kalman Filter. Therefore the solution is the same as the solution obtained by confining the assimilation to the space spanned by the Lyapunov vectors with non-negative Lyapunov exponents. Theoretical arguments and numerical verification are provided to show that the asymptotic state and covariance estimates of the full EKF and of its reduced form, with assimilation in the unstable and neutral subspace (EKF-AUS are the same. The consequences of these findings on applications of Kalman type Filters to chaotic models are discussed.

  19. Prediction of the wetting-induced collapse behaviour using the soil-water characteristic curve

    Science.gov (United States)

    Xie, Wan-Li; Li, Ping; Vanapalli, Sai K.; Wang, Jia-Ding

    2018-01-01

    Collapsible soils go through three distinct phases in response to matric suction decrease during wetting: pre-collapse phase, collapse phase and post-collapse phase. It is reasonable and conservative to consider a strain path that includes a pre-collapse phase in which constant volume is maintained and a collapse phase that extends to the final matric suction to be experienced by collapsible soils during wetting. Upon this assumption, a method is proposed for predicting the collapse behaviour due to wetting. To use the proposed method, two parameters, critical suction and collapse rate, are required. The former is the suction value below which significant collapse deformations take place in response to matric suction decease, and the later is the rate at which void ratio reduces with matric suction in the collapse phase. The value of critical suction can be estimated from the water-entry value taking account of both the microstructure characteristics and collapse mechanism of fine-grained collapsible soils; the wetting soil-water characteristic curve thus can be used as a tool. Five sets of data of wetting tests on both compacted and natural collapsible soils reported in the literature were used to validate the proposed method. The critical suction values were estimated from the water-entry value with parameter a that is suggested to vary between 0.10 and 0.25 for compacted soils and to be lower for natural collapsible soils. The results of a field permeation test in collapsible loess soils were also used to validate the proposed method. The relatively good agreement between the measured and estimated collapse deformations suggests that the proposed method can provide reasonable prediction of the collapse behaviour due to wetting.

  20. Collapse mechanisms and strength prediction of reinforced concrete pile caps

    DEFF Research Database (Denmark)

    Jensen, Uffe G.; Hoang, Linh Cao

    2012-01-01

    . Calculations have been compared with nearly 200 test results found in the literature. Satisfactory agreement has been found. The analyses are conducted on concentrically loaded caps supported by four piles. The paper briefly outlines how the approach may be extended to more complicated loadings and geometries......This paper describes an upper bound plasticity approach for strength prediction of reinforced concrete pile caps. A number of collapse mechanisms are identified and analysed. The procedure leads to an estimate of the load-carrying capacity and an identification of the critical collapse mechanism...

  1. Asymmetric explosion of core-collapse supernovae

    International Nuclear Information System (INIS)

    Kazeroni, Remi

    2016-01-01

    A core-collapse supernova represents the ultimate stage of the evolution of massive stars.The iron core contraction may be followed by a gigantic explosion which gives birth to a neutron star.The multidimensional dynamics of the innermost region, during the first hundreds milliseconds, plays a decisive role on the explosion success because hydrodynamical instabilities are able to break the spherical symmetry of the collapse. Large scale transverse motions generated by two instabilities, the neutrino-driven convection and the Standing Accretion Shock Instability (SASI),increase the heating efficiency up to the point of launching an asymmetric explosion and influencing the birth properties of the neutron star. In this thesis, hydrodynamical instabilities are studied using numerical simulations of simplified models. These models enable a wide exploration of the parameter space and a better physical understanding of the instabilities, generally inaccessible to realistic models.The non-linear regime of SASI is analysed to characterize the conditions under which a spiral mode prevails and to assess its ability to redistribute angular momentum radially.The influence of rotation on the shock dynamics is also addressed. For fast enough rotation rates, a corotation instability overlaps with SASI and greatly impacts the dynamics. The simulations enable to better constrain the effect of non-axisymmetric modes on the angular momentum budget of the iron core collapsing into a neutron star. SASI may under specific conditions spin up or down the pulsar born during the explosion. Finally, an idealised model of the heating region is studied to characterize the non-linear onset of convection by perturbations such as those produced by SASI or pre-collapse combustion inhomogeneities. The dimensionality issue is examined to stress the beneficial consequences of the three-dimensional dynamics on the onset of the explosion. (author) [fr

  2. CT of lobar collapse

    International Nuclear Information System (INIS)

    Suh, D. C.; Im, J. G.; Park, J. H.; Han, M. C.

    1987-01-01

    The computed tomographic (CT) findings of labor collapse are analysed in an attempt to evaluate the patterns of labor collapse and to get the helpful signs in differentiation between benign and malignant causes of collapse. 43 cases of labor collapse with or without endobronchial obstruction were reviewed. In 29 of 43 cases the collapses were caused by lung cancer. Benign causes of labor collapse included tuberculosis(10), broncholith(2), organizing pneumonia(1) and hamartoma(1). The helpful signs favoring malignant cause of the labor collapse were proximal bulging of the collapsed lobe, low density mass within the collapsed lung, and endobronchial lesion. Above described differential findings were especially applicable in cases of upper lobe collapse

  3. A novel cell growth-promoting factor identified in a B cell leukemia cell line, BALL-1

    International Nuclear Information System (INIS)

    Dao, T.; Holan, V.; Minowada, J.

    1993-01-01

    A novel leukemia cell growth-promoting activity has been identified in the culture supernatant from a human B cell leukemia cell line, BALL-1. The supernatant from unstimulated cultures of the BALL-1 cells significantly promoted the growth of 16 out of 24 leukemia/lymphoma cell lines of different lineages (T, B and non-lymphoid) in a minimal concentration of fetal bovine serum (FBS), and 5 out of 12 cases of fresh leukemia cells in FBS-free medium. The growth-promoting sieve filtration and dialysis. The MW of the factor was less than 10 kDa. The growth-promoting activity was heat and acid stable and resistant to trypsin treatment. The factor isolated from the BALL-1 supernatant was distinct from known polypeptide growth factors with MW below 10 kDa, such as epidermal growth factor, transforming growth factor α, insulin-like growth factor I (IGF-I), IGF-II and insulin, as determine by specific antibodies and by cell-growth-promoting tests. The factor is the BALL-1 supernatant did not promote the proliferation of normal human fresh peripheral blood lymphocytes or mouse fibroblast cell line, BALB/C 3T3. In addition to the BALL-1 supernatant, a similar growth-promoting activity was found in the culture supernatant from 13 of 17 leukemia/lymphoma cell lines tested. The activity in these culture supernatant promoted the growth of leukemia/lymphoma cell lines in autocrine and/or paracrine fashions. These observations suggest that the low MW cell growth-promoting activity found in the BALL-1 culture supernatant is mediated by a novel factor which may be responsible for the clonal expansion of particular leukemic clones. (author)

  4. The Goldenrod Ball Gall

    Science.gov (United States)

    Fischer, Richard B.

    1974-01-01

    The paper presents a generalized life history of the goldenrod ball gall, a ball-shaped swelling found almost exclusively on the Canada goldenrod, Solidago canadensis, and caused by a peacock fly know as Eurosta soldiaginis. (KM)

  5. DIRECTED SEARCHES FOR BROADBAND EXTENDED GRAVITATIONAL WAVE EMISSION IN NEARBY ENERGETIC CORE-COLLAPSE SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Van Putten, Maurice H. P. M., E-mail: mvp@sejong.ac.kr [Room 614, Astronomy and Space Science, Sejong University, 98 Gunja-Dong Gwangin-gu, Seoul 143-747 (Korea, Republic of)

    2016-03-10

    Core-collapse supernovae (CC-SNe) are factories of neutron stars and stellar-mass black holes. SNe Ib/c stand out as potentially originating in relatively compact stellar binaries and they have a branching ratio of about 1% into long gamma-ray bursts. The most energetic events probably derive from central engines harboring rapidly rotating black holes, wherein the accretion of fall-back matter down to the innermost stable circular orbit (ISCO) offers a window into broadband extended gravitational wave emission (BEGE). To search for BEGE, we introduce a butterfly filter in time–frequency space by time-sliced matched filtering. To analyze long epochs of data, we propose using coarse-grained searches followed by high-resolution searches on events of interest. We illustrate our proposed coarse-grained search on two weeks of LIGO S6 data prior to SN 2010br (z = 0.002339) using a bank of up to 64,000 templates of one-second duration covering a broad range in chirp frequencies and bandwidth. Correlating events with signal-to-noise ratios > 6 from the LIGO L1 and H1 detectors reduces the total to a few events of interest. Lacking any further properties reflecting a common excitation by broadband gravitational radiation, we disregarded these as spurious. This new pipeline may be used to systematically search for long-duration chirps in nearby CC-SNe from robotic optical transient surveys using embarrassingly parallel computing.

  6. Radiologic evaluation of right middle lobe collapse

    International Nuclear Information System (INIS)

    Kwun, Dae Young; Kim, Jong Deok; Kim, Jong Chul

    1989-01-01

    There are many pathogenetic factors for collapse of right middle lobe; profuse peribronchial clustering of lymph nodes about the right middle lobe bronchus, poor drainage of the bronchus because of its acute angle of take-off from the intermediate bronchus, and the isolation of this small lobe from the right upper and lower lobes, and thus from the aerating effects of collateral ventilation. Retrospectively we reviewed 36 cases of right of right middle lobe collapse of which causes were confirmed by histopathologic or bronchographic findings during the recent 6 years from March 1983 to February 1988 at Inje College Pusan Paik Hospital, and obtained the following results: 1. Male to female ratio was 1:1:4,and peak incidence (64%) was in the fifth and sixth decades with the mean age of 51.1 years. 2. Bronchiectasis was the most common cause (30.6%), and the others were chronic bronchitis (25.0%), pulmonary tuberculosis (19.4%), lung cancer (16.7%), and non-specific inflammatory disease (8.3%). This suggests benign disease is 5 times more common cause of right middle lobe collapse than lung cancer. 3. Among the plain chest radiolograph findings, obliteration of right cardiac border and triangular radiopaque density were the most frequent findings(77.8% in each) and the next was downward and anterior displacement of minor and major fissures (55.6%) 4. Bronchography was done in 11 cases; bronchiectasis was found in 8 cases and chronic bronchitis in 3 cases. Right middle lobe bronchus was obstructed in 2 cases of chronic bronchitis. 5. Chest CT scan was performed in 4 cases of lung cancer, 2 of non-specific inflammatory disease, and 1 of pulmonary tuberculosis: all of lung cancer revealed hilar mass, budged or lobulated fissures, in homogenous density, and mediastinal lymph node enlargement, and all benign disease showed homogenous density and flat to concave fissures. Right middle lobar bronchus narrowing was seen in 5 cases and its obstruction in 2 cases

  7. Dynamics of a Bouncing Ball

    Science.gov (United States)

    Liang, Shiuan-Ni; Lan, Boon Leong

    The dynamics of a bouncing ball undergoing repeated inelastic impacts with a table oscillating vertically in a sinusoidal fashion is studied using Newtonian mechanics and general relativistic mechanics. An exact mapping describes the bouncing ball dynamics in each theory. We show, contrary to expectation, that the trajectories predicted by Newtonian mechanics and general relativistic mechanics from the same parameters and initial conditions for the ball bouncing at low speed in a weak gravitational field can rapidly disagree completely. The bouncing ball system could be realized experimentally to test which of the two different predicted trajectories is correct.

  8. Simulation of ball motion and energy transfer in a planetary ball mill

    International Nuclear Information System (INIS)

    Lu Sheng-Yong; Mao Qiong-Jing; Li Xiao-Dong; Yan Jian-Hua; Peng Zheng

    2012-01-01

    A kinetic model is proposed for simulating the trajectory of a single milling ball in a planetary ball mill, and a model is also proposed for simulating the local energy transfer during the ball milling process under no-slip conditions. Based on the kinematics of ball motion, the collision frequency and power are described, and the normal impact forces and effective power are derived from analyses of collision geometry. The Hertzian impact theory is applied to formulate these models after having established some relationships among the geometric, dynamic, and thermophysical parameters. Simulation is carried out based on two models, and the effects of the rotation velocity of the planetary disk Ω and the vial-to-disk speed ratio ω/Ω on other kinetic parameters is investigated. As a result, the optimal ratio ω/Ω to obtain high impact energy in the standard operating condition at Ω = 800 rpm is estimated, and is equal to 1.15. (interdisciplinary physics and related areas of science and technology)

  9. On the isoperimetric rigidity of extrinsic minimal balls

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, V.

    2003-01-01

    We consider an m-dimensional minimal submanifold P and a metric R-sphere in the Euclidean space R-n. If the sphere has its center p on P, then it will cut out a well defined connected component of P which contains this center point. We call this connected component an extrinsic minimal R-ball of P....... The quotient of the volume of the extrinsic ball and the volume of its boundary is not larger than the corresponding quotient obtained in the space form standard situation, where the minimal submanifold is the totally geodesic linear subspace R-m. Here we show that if the minimal submanifold has dimension...... larger than 3, if P is not too curved along the boundary of an extrinsic minimal R-ball, and if the inequality alluded to above is an equality for the extrinsic minimal ball, then the minimal submanifold is totally geodesic....

  10. Moment tensor analysis of the 3 September 2017 DPRK announced nuclear explosion and collapse aftershock

    Science.gov (United States)

    Ichinose, G. A.; Ford, S. R.; Chiang, A.; Walter, W. R.; Dreger, D. S.

    2017-12-01

    The Democratic People's Republic of Korea (DPRK) conducted its sixth announced nuclear test on 3 September 2017, 03:30:00 with a magnitude of 6.1 (IDC mb). At 03:38:27, there was an aftershock of magnitude 4.1 (IDC mb). Moment tensor analysis using regional long-period surface waves was performed to identify the source type of these two events. The first event was an explosive isotropic source with total seismic moment magnitude of Mw 5.34 (Mo=1.16e+17 Nm) with strong 66% isotropic component (eigenvalues: 1.30e+17, 0.75e+17, 0.44e+17 Nm). The second event was a closing crack source with an Mw 4.64 (Mo=1.04e+17 Nm) also with a strong 68% isotropic component (eigenvalues: -4.82e+16, -5.33e+16, -10.93e+16 Nm). We used the same stations within 360-1140 km for inversion of both events (stations: IC.MDJ, IC.BJT, IC.HIA) and predict the long-period displacements at KG.TJN and IU.INCN. We used a 1-D velocity model appropriate for active tectonic regions and band pass the data between periods of 20 and 100 sec. Waveform time-shifts were incorporated from previous event-station pairs to account for velocity model inadequacies. Both DPRK events source-types plot within the population of other NNSS nuclear and western US collapse events (Ford et al., 2009) on the fundamental lune (Tape and Tape, 2012). The DPRK collapse event is similar to the hole collapse 0h21m26s after the 5 September 1982 Atrisco shot at NNSS (Springer et al., 2002; DOE NV-209). The DPRK collapse could be explained by a complete or partial apical cavity collapse. The estimated collapse volume is 122000-277000 m3 and crack radius is 30-40 m given the seismic moment, elastic moduli for granite and a closing crack model (Mueller, 2001). In comparison to Denny and Johnson (1994) cavity-yield scaling in granite, the cavity radius ranges from 40 to 60 m given an explosion yield range of 140-400 kT. This collapse event is noteworthy because large aftershocks are rare in nuclear testing and even more rare are

  11. Neutrons and the crystal ball experiments

    International Nuclear Information System (INIS)

    Alyea, J.; Grosnick, D.; Koetke, D.; Manweiler, R.; Spinka, H.; Stanislaus, S.

    1997-01-01

    The Crystal Ball detector, as originally constructed, consisted of a set of 672 optically-isolated NaI crystals, forming an approximately spherical shell and each crystal viewed by a photomultiplier, a charged-particle tracker within the NaI shell, and two endcaps to cover angles close to two colliding beams. The detector geometry subtends a solid angle of about 93% of 4π st (20 degree le θ le 160degree and 0degree le φ le 360degree) from the center. The Crystal Ball detector was used for two long series of experiments at the e + e - colliding beam accelerators SPEAR [1, 2, 3, 4] at SLAC and DORIS [5, 6, 7, 8] at DESY. A new set of measurements using the Crystal Ball detector is planned at the Brookhaven National Laboratory Alternating Gradient Synchrotrons (BNL AGS). These new experiments will use the 672 NaI crystals from the original detector, but neither the tracker nor endcaps. The ''Crystal Ball'' in this note will refer only to the set of NaI crystals. Initially, the reactions to be studied will include π - pr a rrow neutrals with pion beam momenta approximately400-750 MeV/c and K - pr a rrow neutrals with kaon beam momenta approximately600-750 MeV/c. Each of these reactions will include a neutron in the final state. whereas the fraction of e + e - interactions with neutrons at SLAC or DESY was quite small. Consequently, there is relatively little experience understanding the behavior of neutrons in the Crystal Ball

  12. 2012 Problem 15: Frustrating Golf Ball

    Science.gov (United States)

    Huang, Shan; Zhu, Zheyuan; Gao, Wenli; Wang, Sihui

    2015-10-01

    This paper studies the condition for a golf ball to escape from a hole. The two determining factors are the ball's initial velocity v0 and its deviation from the center of the hole d. There is a critical escaping velocity vc for every deviation d. The ball's motion is analyzed by calculating the change of velocity whenever the ball collides with the hole. The critical conditions predicted by our theory are verified through experiment.

  13. Effects of processing parameters on the synthesis of (K0.5Na0.5)NbO3 nanopowders by reactive high-energy ball milling method.

    Science.gov (United States)

    Nguyen, Duc Van

    2014-01-01

    The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C.

  14. Birth ball or heat therapy? A randomized controlled trial to compare the effectiveness of birth ball usage with sacrum-perineal heat therapy in labor pain management.

    Science.gov (United States)

    Taavoni, Simin; Sheikhan, Fatemeh; Abdolahian, Somayeh; Ghavi, Fatemeh

    2016-08-01

    Labor pain and its management is a major concern for childbearing women, their families and health care providers. This study aimed to investigate the effects of two non-pharmacological methods such as birth ball and heat therapy on labor pain relief. This randomized control trial was undertaken on 90 primiparous women aged 18-35 years old who were randomly assigned to two intervention (birth ball and heat) and control groups. The pain score was recorded by using Visual Analogue Scale (VAS) before the intervention and every 30 min in three groups until cervical dilatation reached 8 cm. The mean pain severity score in the heat therapy group was less than that of in control group at 60 and 90 min after intervention (p pain scores in the birth ball group after all three investigated times in comparison to control group. Both heat therapy and birth ball can use as inexpensive complementary and low risk treatment for labor pain. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Gravitational Collapse of Radiating Dyon Solution and Cosmic Censorship Hypothesis

    International Nuclear Information System (INIS)

    Patil, K. D.; Zade, S. S.; Mohod, A. N.

    2008-01-01

    We investigate the possibility of cosmic censorship violation in the gravitational collapse of radiating dyon solution. It is shown that the final outcome of the collapse depends sensitively on the electric and magnetic charge parameters. The graphs of the outer apparent horizon, inner Cauchy horizon for different values of parameters are drawn. It is found that the electric and magnetic components push the apparent horizon towards the retarded time-coordinate axis, which in turn reduces the radius of the apparent horizon in Vaidya spacetime. Also, we extend the earlier work of Chamorro and Virbhadra [Pramana, J. Phys. 45 (1995) 181

  16. Neural extrapolation of motion for a ball rolling down an inclined plane.

    Science.gov (United States)

    La Scaleia, Barbara; Lacquaniti, Francesco; Zago, Myrka

    2014-01-01

    It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions) and slope (30°, 45° or 60°). In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1). However, even when participants punched an imaginary moving ball (Experiment 2) or drew in air the imaginary trajectory (Experiment 3), they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

  17. Neural extrapolation of motion for a ball rolling down an inclined plane.

    Directory of Open Access Journals (Sweden)

    Barbara La Scaleia

    Full Text Available It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions and slope (30°, 45° or 60°. In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1. However, even when participants punched an imaginary moving ball (Experiment 2 or drew in air the imaginary trajectory (Experiment 3, they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

  18. Extended non-local games and monogamy-of-entanglement games.

    Science.gov (United States)

    Johnston, Nathaniel; Mittal, Rajat; Russo, Vincent; Watrous, John

    2016-05-01

    We study a generalization of non-local games-which we call extended non-local games -in which the players, Alice and Bob, initially share a tripartite quantum state with the referee. In such games, the winning conditions for Alice and Bob may depend on the outcomes of measurements made by the referee, on its part of the shared quantum state, in addition to Alice and Bob's answers to randomly selected questions. Our study of this class of games was inspired by the monogamy-of-entanglement games introduced by Tomamichel, Fehr, Kaniewski and Wehner, which they also generalize. We prove that a natural extension of the Navascués-Pironio-Acín hierarchy of semidefinite programmes converges to the optimal commuting measurement value of extended non-local games, and we prove two extensions of results of Tomamichel et al.  concerning monogamy-of-entanglement games.

  19. Karst collapse in cities and mining areas, China

    International Nuclear Information System (INIS)

    Jian Chen

    1988-01-01

    Karst collapse is a dynamic geological phenomenon, in which the rock mass or deposits overlying the karstified zone subsides down along the karst cavity, resulting in a collapse pit or sinkhole. After discussing the typical examples of collapse emerging in the karst cities and mines in provinces and regions of South China, such as Guangdong, Guangxi, Hunan, Hubei, Zhejiang, Yunnan, Guizhou, and Jiangxi, it is considered that human activities of economy and production have become a major effect in causing karst collapse. Man-made collapses make 66.4 percent of the total, whereas natural ones 33.6 percent. Most of the collapses occurred to the area with soil overburden (96.7 percent), only a few in areas of bedrock overburden (3.3 percent). The karst collapses have a close relationship with the extent of karst development, the character and the thickness of overburden, and the dynamic condition of underground water. Collapse usually occurs in those parts of an area that are more intensely karstified, with soil thickness less than 5 m and a high amplitude of water table fluctuation. Many kinds of mechanical effects are caused by pumping or draining on the over-burden and destroying its equilibrium, leading to the collapse. These effects included the support loss and load-added effect, penetrating suffusion, gas explosion, water-hammer, suction pressure erosion, and liquefaction effects. The collapses are the result of varied comprehensive effects, particularly the support loss and load-added, and penetrating suffusion

  20. Neutrinos and supernova collapse

    International Nuclear Information System (INIS)

    Colgate, S.A.; Petschek, A.G.

    1980-01-01

    The neutrino emission resulting from stellar collapse and supernova formation is reviewed. The electron capture and consequent neutronization of the collapsing stellar matter at the end of evolution determines both the initial adiabat of core collapse as well as the trapped lepton fraction. The initial lepton fraction, Y/sub l/ = .48 supplies the pressure for neutral support of the star at the Chandrasekhar limit. High trapping values, Y/sub l/ = .4, lead to soft core collapses; low values to harder collapses. The value of Y/sub l/ is presently in dispute. The neutrino emission from initial electron capture is relatively small. A strong core-bounce shock releases both electron neutrino as well as thermal muon and tau neutrinos. Subsequent neutrino emission and cooling can sometimes lead to an unstable buoyancy gradient in the core in which case unstable core overturn is expected. Calculations have already shown the importance of the largest possible eddy or equivalently the lowest mode of overturn. Present models of low lepton trapping ratio lead to high entropy creation by the reflected shock and the stabilization of the core matter against overturn. In such cases the exterior matter must cool below an entropy of approximately s/k approx. = 2 to become unstable. This may require too long a time approximately one second for neutrino cooling from a neutrinosphere at rho approx. = 2 x 10 12 g cm -3 . On the other hand, high values of Y/sub l/ such as .4 lead to softer bounces at lower density and values of the critical stabilizing entropy of 3 or higher. Under such circumstances, core overturn can still occur

  1. Therapeutic CPAP Level Predicts Upper Airway Collapsibility in Patients With Obstructive Sleep Apnea.

    Science.gov (United States)

    Landry, Shane A; Joosten, Simon A; Eckert, Danny J; Jordan, Amy S; Sands, Scott A; White, David P; Malhotra, Atul; Wellman, Andrew; Hamilton, Garun S; Edwards, Bradley A

    2017-06-01

    Upper airway collapsibility is a key determinant of obstructive sleep apnea (OSA) which can influence the efficacy of certain non-continuous positive airway pressure (CPAP) treatments for OSA. However, there is no simple way to measure this variable clinically. The present study aimed to develop a clinically implementable tool to evaluate the collapsibility of a patient's upper airway. Collapsibility, as characterized by the passive pharyngeal critical closing pressure (Pcrit), was measured in 46 patients with OSA. Associations were investigated between Pcrit and data extracted from patient history and routine polysomnography, including CPAP titration. Therapeutic CPAP level, demonstrated the strongest relationship to Pcrit (r2=0.51, p CPAP level (6.2 ± 0.6 vs. 10.3 ± 0.4 cmH2O, p -2 cmH2O). A therapeutic CPAP level ≤8.0 cmH2O was sensitive (89%) and specific (84%) for detecting a mildly collapsible upper airway. When applied to the independent validation data set (n = 74), this threshold maintained high specificity (91%) but reduced sensitivity (75%). Our data demonstrate that a patient's therapeutic CPAP requirement shares a strong predictive relationship with their Pcrit and may be used to accurately differentiate OSA patients with mild airway collapsibility from those with moderate-to-severe collapsibility. Although this relationship needs to be confirmed prospectively, our findings may provide clinicians with better understanding of an individual patient's OSA phenotype, which ultimately could assist in determining which patients are most likely to respond to non-CPAP therapies. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  2. Effect of a ball skill intervention on children's ball skills and cognitive functions

    NARCIS (Netherlands)

    Westendorp-Haverdings, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

    Purpose: This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning

  3. Numerical simulation and analysis of ball valve three-dimensional flow based on CFD

    International Nuclear Information System (INIS)

    Zhang, S C; Zhang, Y L; Fang, Z M

    2012-01-01

    The new rotor oil-gas mixture pump that added ball valves in its export is a kind of innovative products, which can better adapt to the oil and gas mixed condition. In order to explore the rule of flow field in the export ball valve of new rotor oil-gas mixture pump, established the 3 d model of ball valve flow field was established. Using the FLUENT software, combining the standard k-ε turbulent model with multiphase flow technology and adopting the SIMPLE algorithm to simulate the 3 d gas-liquid two phase flow field in export ball valve of new rotor oil-gas mixture pump. In the different conditions that the volume of gas rate was 25%, 50%, 75%, through analyzing the velocity field, stress field and the distribution of the liquid and gas with the ball valve open height respectively at 3mm, 5mm, 7mm. Discussed how open height and different volume of gas rate to influence the field in export ball valve in the process of gas-liquid mixing was discussed. The simulation results showed that the greater the open height, the smaller the difference pressure of ball valve; the gap velocity decreasing with the open height increasing. The gas is mainly distributed in the vicinity of the valve ball in the process of gas-liquid mixing. The gas liquid ratio has a little effect on the gap velocity in the same open height. The results showed the flow field forms in the ball valve directly, to a certain degree, it had released the rules of gas-liquid flow in the valve and provided the theoretical guidance for design and optimization of the new rotor oil-gas mixture pump export ball valve.

  4. Ball mounting fixture for a roundness gage

    Science.gov (United States)

    Gauler, Allen L.; Pasieka, Donald F.

    1983-01-01

    A ball mounting fixture for a roundness gage is disclosed. The fixture includes a pair of chuck assemblies oriented substantially transversely with respect to one another and mounted on a common base. Each chuck assembly preferably includes a rotary stage and a wobble plate affixed thereto. A ball chuck affixed to each wobble plate is operable to selectively support a ball to be measured for roundness, with the wobble plate permitting the ball chuck to be tilted to center the ball on the axis of rotation of the rotary stage. In a preferred embodiment, each chuck assembly includes a vacuum chuck operable to selectively support the ball to be measured for roundness. The mounting fixture enables a series of roundness measurements to be taken with a conventional rotating gagehead roundness instrument, which measurements can be utilized to determine the sphericity of the ball.

  5. Some results on rotating fluid balls of Petrov type D

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, M [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); Eriksson, D [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); Fodor, G [KFKI Research Institute for Particle and Nuclear Physics, H-1525, Budapest 114, P.O.B. 49 (Hungary); Racz, I [KFKI Research Institute for Particle and Nuclear Physics, H-1525, Budapest 114, P.O.B. 49 (Hungary)

    2007-05-15

    The second order perturbative field equations for slowly and rigidly rotating perfect fluid balls of Petrov type D are solved numerically. It is found that all the slowly and rigidly rotating perfect fluid balls up to second order, irrespective of Petrov type, may be matched to a possibly non-asymptotically flat stationary axisymmetric vacuum exterior. A subspace of the parameter space is identified for which the solutions can be matched to an asymptotically flat exterior vacuum region. The physical properties like equations of state, shapes and speeds of sound are determined for a number of solutions.

  6. DRG axon elongation and growth cone collapse rate induced by Sema3A are differently dependent on NGF concentration.

    Science.gov (United States)

    Kaselis, Andrius; Treinys, Rimantas; Vosyliūtė, Rūta; Šatkauskas, Saulius

    2014-03-01

    Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon's regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate.

  7. Structure and magnetism of SmCo5 nanoflakes prepared by surfactant-assisted ball milling with different ball sizes

    International Nuclear Information System (INIS)

    Nie, Junwu; Han, Xianghua; Du, Juan; Xia, Weixing; Zhang, Jian; Guo, Zhaohui; Yan, Aru; Li, Wei; Ping Liu, J.

    2013-01-01

    Anisotropic magnetic SmCo 5 nanoflakes have been fabricated by surfactant-assisted ball milling (SABM) using hardened steel balls of one of the following sizes: 4, 6.5, 9.5 and 12.7 mm in diameters. The magnetic properties of SmCo 5 particles prepared by SABM with different milling ball sizes in diameters were investigated systematically. It was showed that the nanoflakes milled by amount of small size balls had a higher coercivity and lower anisotropy, i.e., worse grain orientation although in a short milling time while the nanoflakes prepared with same weight of big balls tend to have a lower coercivity, better grain orientation. The coercivity mechanism of the nanoflake was studied and it was mainly dominated with the domain-wall pinning. The SEM analysis shows that the morphology of nanoflakes prepared with different ball sizes are almost the same when the balls to powder weight ratio is fixed. The different magnetic properties caused by different ball sizes are mainly due to the different microstructure changes, i.e, grain refinement and c-axis orientation, which are demonstrated by X-ray diffraction (XRD) analysis and transmission electron microscope (TEM). Based on the experiments above, a combined milling process was suggested and done to improve magnetic properties as your need. - Highlights: • We fabricated anisotropic magnetic SmCo 5 nanoflakes by surfactant-assisted ball milling (SABM). • We investigated the magnetic properties of SmCo 5 particles systematically. It was showed that the coercivity, high or low, and grain orientation, good or bad, were influenced strongly by balls size. The different magnetisms caused by different ball sizes is mainly due to the different microstructure changes. • The coercivity mechanism of the nanoflake was studied and it was mainly dominated with the domain-wall pinning

  8. Electrostatic charge bounds for ball lightning models

    International Nuclear Information System (INIS)

    Stephan, Karl D

    2008-01-01

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings

  9. Respiratory disease in ball pythons (Python regius) experimentally infected with ball python nidovirus.

    Science.gov (United States)

    Hoon-Hanks, Laura L; Layton, Marylee L; Ossiboff, Robert J; Parker, John S L; Dubovi, Edward J; Stenglein, Mark D

    2018-04-01

    Circumstantial evidence has linked a new group of nidoviruses with respiratory disease in pythons, lizards, and cattle. We conducted experimental infections in ball pythons (Python regius) to test the hypothesis that ball python nidovirus (BPNV) infection results in respiratory disease. Three ball pythons were inoculated orally and intratracheally with cell culture isolated BPNV and two were sham inoculated. Antemortem choanal, oroesophageal, and cloacal swabs and postmortem tissues of infected snakes were positive for viral RNA, protein, and infectious virus by qRT-PCR, immunohistochemistry, western blot and virus isolation. Clinical signs included oral mucosal reddening, abundant mucus secretions, open-mouthed breathing, and anorexia. Histologic lesions included chronic-active mucinous rhinitis, stomatitis, tracheitis, esophagitis and proliferative interstitial pneumonia. Control snakes remained negative and free of clinical signs throughout the experiment. Our findings establish a causal relationship between nidovirus infection and respiratory disease in ball pythons and shed light on disease progression and transmission. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Extended solid solubility of a Co–Cr system by mechanical alloying

    International Nuclear Information System (INIS)

    Betancourt-Cantera, J.A.; Sánchez-De Jesús, F.; Torres-Villaseñor, G.; Bolarín-Miró, A.M.; Cortés-Escobedo, C.A.

    2012-01-01

    Highlights: ► Solubility of the Co–Cr system is modified by means of Mechanical Alloying (MA). ► MA induces the formation of new solid solutions of Co–Cr system in non-equilibrium. ► MA promote the formation of metastable Co–Cr phases with greater solubility. - Abstract: Mechanical alloying, MA, has been successfully used to extend the limits of solid solubility in many commercially important metallic systems. The aim of this work is to demonstrate that MA modifies the solid solubility of the Co–Cr system. Co and Cr elemental powders were used as precursors and mixed in an adequate weight ratio to obtain Co 100−x Cr x (0 ≤ x ≤ 100, Δx = 10) to study the effect of mechanical processing in the solubility of the Co–Cr system. Processing was carried out at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media with a ball:powder weight ratio of 10:1. Crystalline structure characterization of the milled powders was conducted using X-ray diffraction, and phase transformations as a function of composition were analyzed. Thermal analysis confirmed structural changes occurred in the mechanically alloyed powders. The evolution of the phase transformations with composition is reported for each composition. The results showed that after high energy ball milling for 7 h, the solid solubility between Co and Cr could be evidently extended, despite the low solid solubility at the equilibrium conditions of this system. Additionally, the micrographs of the milled powders showed that increasing composition of chromium changes the shape and size of the particles while simultaneously reducing their agglomeration; this effect is possibly attributed to the brittleness of elemental chrome.

  11. Extended solid solubility of a Co-Cr system by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Betancourt-Cantera, J.A. [Area Academica de Ciencias de la Tierra y Materiales, UAEH Carr. Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Sanchez-De Jesus, F., E-mail: fsanchez@uaeh.edu.mx [Area Academica de Ciencias de la Tierra y Materiales, UAEH Carr. Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Torres-Villasenor, G. [Instituto de Investigaciones en Materiales-UNAM, Apdo. Postal 70-360, 04510 Mexico, DF (Mexico); Bolarin-Miro, A.M. [Area Academica de Ciencias de la Tierra y Materiales, UAEH Carr. Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Cortes-Escobedo, C.A. [Centro de Investigacion e Innovacion Tecnologica del IPN Cda. CECATI S/N, Col. Sta. Catarina, Azcapotzalco, 02250 Mexico, DF (Mexico)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer Solubility of the Co-Cr system is modified by means of Mechanical Alloying (MA). Black-Right-Pointing-Pointer MA induces the formation of new solid solutions of Co-Cr system in non-equilibrium. Black-Right-Pointing-Pointer MA promote the formation of metastable Co-Cr phases with greater solubility. - Abstract: Mechanical alloying, MA, has been successfully used to extend the limits of solid solubility in many commercially important metallic systems. The aim of this work is to demonstrate that MA modifies the solid solubility of the Co-Cr system. Co and Cr elemental powders were used as precursors and mixed in an adequate weight ratio to obtain Co{sub 100-x}Cr{sub x} (0 {<=} x {<=} 100, {Delta}x = 10) to study the effect of mechanical processing in the solubility of the Co-Cr system. Processing was carried out at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media with a ball:powder weight ratio of 10:1. Crystalline structure characterization of the milled powders was conducted using X-ray diffraction, and phase transformations as a function of composition were analyzed. Thermal analysis confirmed structural changes occurred in the mechanically alloyed powders. The evolution of the phase transformations with composition is reported for each composition. The results showed that after high energy ball milling for 7 h, the solid solubility between Co and Cr could be evidently extended, despite the low solid solubility at the equilibrium conditions of this system. Additionally, the micrographs of the milled powders showed that increasing composition of chromium changes the shape and size of the particles while simultaneously reducing their agglomeration; this effect is possibly attributed to the brittleness of elemental chrome.

  12. A SPECT reconstruction method for extending parallel to non-parallel geometries

    International Nuclear Information System (INIS)

    Wen Junhai; Liang Zhengrong

    2010-01-01

    Due to its simplicity, parallel-beam geometry is usually assumed for the development of image reconstruction algorithms. The established reconstruction methodologies are then extended to fan-beam, cone-beam and other non-parallel geometries for practical application. This situation occurs for quantitative SPECT (single photon emission computed tomography) imaging in inverting the attenuated Radon transform. Novikov reported an explicit parallel-beam formula for the inversion of the attenuated Radon transform in 2000. Thereafter, a formula for fan-beam geometry was reported by Bukhgeim and Kazantsev (2002 Preprint N. 99 Sobolev Institute of Mathematics). At the same time, we presented a formula for varying focal-length fan-beam geometry. Sometimes, the reconstruction formula is so implicit that we cannot obtain the explicit reconstruction formula in the non-parallel geometries. In this work, we propose a unified reconstruction framework for extending parallel-beam geometry to any non-parallel geometry using ray-driven techniques. Studies by computer simulations demonstrated the accuracy of the presented unified reconstruction framework for extending parallel-beam to non-parallel geometries in inverting the attenuated Radon transform.

  13. Collapse postulate for observables with continuous area

    International Nuclear Information System (INIS)

    Srinivas, M.D.

    1979-03-01

    In order to provide a mathematical framework for discussing the statistical correlations between the outcomes, when an arbitrary sequence of observables are measured, it is necessary to generalize the conventional von Neumann-Lueders collapse postulate to observables with a continuous spectrum. It is shown that the standard prescription in conventional quantum theory for the joint probabilities of compatible observables is sufficient to characterize, more or less completely, the appropriate ''generalized collapse postulate'' which associates with each observable a unique ''finitely additive expectation valued measure''. An interesting feature of the collapse associated with observables with continuous spectra, which again follows from the basic principles of conventional quantum theory, is that it must be formulated in terms of the so-called non-normal conditional expectations, which implies that the joint probabilities associated with successive observations of such observables are not in general σ-additive. The implications of this non-σ-additivity on the determination of expectation values, correlation functions etc., are also investigated. It is demonstrated that the basic prescriptions introduced in this paper constitute a natural completion of the framework of conventional quantum theory for discussing the statistics of an arbitrary sequence of observations

  14. Collapse postulate for observables with continuous spectra

    International Nuclear Information System (INIS)

    Srinivas, M.D.; Madras Univ.

    1980-01-01

    In order to provide a mathematical framework for discussing the statistical correlations between the outcomes, when an arbitrary sequence of observables are measured, it is necessary to generalize the conventional von Neumann-Lueders collapse postulate to observables with a continuous spectrum. It is shown that the standard prescription in conventional quantum theory for the joint probabilities of compatible observables is sufficient to characterize, more or less completely, the appropriate 'generalized collapse postulate' which associates with each observable a unique 'finitely additive expectation valued measure'. An interesting feature of the collapse associated with observables with continuous spectra, which again follows from the basic principles of conventional quantum theory, is that it must be formulated in terms of the so-called non-normal conditional expectations, which implies that the joint probabilities associated with successive observations of such observables are not in general sigma-additive. The implications of this non-sigma-additivity on the determination of expectation values, correlation functions etc., are also investigated. It is demonstrated that the basic prescriptions introduced in this paper constitute a natural completion of the framework of conventional quantum theory for discussing the statistics of an arbitrary sequence of observations. (orig.) 891 HJ/orig. 892 CKA

  15. Supersymmetric Q-balls theory and cosmology

    CERN Document Server

    Kusenko, A

    1999-01-01

    MSSM predicts the existence of Q-balls, some of which can be entirely stable. Both stable and unstable Q-balls can play an important role in cosmology. In particular, Affleck-Dine baryogenesis can result in a copious production of stable baryonic Q-balls, which can presently exist as a form of dark matter.

  16. Multigroup cross section collapsing optimization of a He-3 detector assembly model using deterministic transport techniques

    International Nuclear Information System (INIS)

    Huang, Mi; Yi, Ce; Manalo, Kevin L.; Sjoden, Glenn E.

    2011-01-01

    Multigroup optimization is performed on a neutron detector assembly to examine the validity of transport response in forward and adjoint modes. For SN transport simulations, we discuss the multigroup collapse of an 80 group library to 40, 30, and 16 groups, constructed from using the 3-D parallel PENTRAN and macroscopic cross section collapsing with YGROUP contribution weighting. The difference in using P_1 and P_3 Legendre order in scattering cross sections is investigated; also, associated forward and adjoint transport responses are calculated. We conclude that for the block analyzed, a 30 group cross section optimizes both computation time and accuracy relative to the 80 group transport calculations. (author)

  17. The relationships between impact location and post-impact ball speed, bat torsion, and ball direction in cricket batting.

    Science.gov (United States)

    Peploe, C; McErlain-Naylor, S A; Harland, A R; King, M A

    2018-06-01

    Three-dimensional kinematic data of bat and ball were recorded for 239 individual shots performed by twenty batsmen ranging from club to international standard. The impact location of the ball on the bat face was determined and assessed against the resultant instantaneous post-impact ball speed and measures of post-impact bat torsion and ball direction. Significant negative linear relationships were found between post-impact ball speed and the absolute distance of impact from the midline medio-laterally and sweetspot longitudinally. Significant cubic relationships were found between the distance of impact from the midline of the bat medio-laterally and both a measure of bat torsion and the post-impact ball direction. A "sweet region" on the bat face was identified whereby impacts within 2 cm of the sweetspot in the medio-lateral direction, and 4.5 cm in the longitudinal direction, caused reductions in ball speed of less than 6% from the optimal value, and deviations in ball direction of less than 10° from the intended target. This study provides a greater understanding of the margin for error afforded to batsmen, allowing researchers to assess shot success in more detail, and highlights the importance of players generating consistently central impact locations when hitting for optimal performance.

  18. Non-adiabatic radiative collapse of a relativistic star under different

    Indian Academy of Sciences (India)

    The collapse of a star filled with a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid under anisotropic ... Department of Physics, P.D. Women's College, Jalpaiguri 735 101, India; Department of Mathematics, Sardar Patel University, Vallabh Vidyanagar 388 120, India ...

  19. Laboratory demonstration of ball lightning

    International Nuclear Information System (INIS)

    Egorov, Anton I; Stepanov, Sergei I; Shabanov, Gennadii D

    2004-01-01

    A common laboratory facility for creating glowing flying plasmoids akin to a natural ball lightning, allowing a number of experiments to be performed to investigate the main properties of ball lightning, is described. (methodological notes)

  20. Relationship between collapse history and ore distribution in Sage Breccia pipe, northwestern Arizona

    International Nuclear Information System (INIS)

    Brown, N.A.; Mead, R.H.; McMurray, J.M.

    1989-01-01

    The Sage pipe is similar to other collapse breccia pipes in northern Arizona which have their beginnings in cave systems in the Redwall Limestone. Stoping of successively younger units caused the upward propagation of the pipe and provided the pipe-filling breccia. The Sage pipe extends at least 2,500 ft (762 m) vertically; the horizontal dimensions range from 100 to 300 ft (30.5-91 m), depending on variations in the adjoining host stratigraphy. The composition and distribution of breccia facies suggest a complex collapse history and variability in the mechanics of collapse. Rock failure took place both by block stoping and by decementation of sandstone and siltstone followed by flow of unconsolidated grains. The resulting breccias range from matrix to fragment-dominated, to sand flow breccia resulting from flow of individual grains. Episodic secondary collapse or readjustment within the breccia pile complicated facies distribution. Paragenetic studies indicate multiple periods of mineralization at Sage resulting in enrichment in an extensive suite of elements. Ore-grade uranium mineralization extends vertically for nearly 700 ft (213 m). Lateral distribution of the ore is variable and is directly related to breccia facies distribution. In generally, the more permeable breccias tend to be the most highly mineralized. Fracture, intergranular, and interfragment permeability were important to mineral distribution. Breccia continuity or plumbing was also important to lateral and vertical mineral distribution

  1. Research in nuclear astrophysics: stellar collapse and supernovae. Progress report and renewal proposal

    International Nuclear Information System (INIS)

    Lattimer, J.M.; Yahil, A.

    1982-01-01

    The interaction between nuclear theory and the problem of stellar collapse and supernovae is examined. Experimentally determined nuclear parameters (compressibility, symmetry energies, level densities) are being used to determine a finite temperature equation of state. Detailed studies of shock propagation, neutrino transport and electron capture in stellar collapse are continued. The long-term evolution of collapsed stars (hot proto-neutron stars) is extended to find characteristic signatures of the neutrino spectrum, important for the experiments that can detect extraterrestrial neutrinos. A novel, conservative hydrodynamical code is used to alleviate the requirement of using artificial viscosity to follow shocks. This is coupled with a new, fast numerical scheme for the equation of state

  2. Review of collapse triggering mechanism of collapsible soils due to wetting

    Directory of Open Access Journals (Sweden)

    Ping Li

    2016-04-01

    Full Text Available Loess soil deposits are widely distributed in arid and semi-arid regions and constitute about 10% of land area of the world. These soils typically have a loose honeycomb-type meta-stable structure that is susceptible to a large reduction in total volume or collapse upon wetting. Collapse characteristics contribute to various problems to infrastructures that are constructed on loess soils. For this reason, collapse triggering mechanism for loess soils has been of significant interest for researchers and practitioners all over the world. This paper aims at providing a state-of-the-art review on collapse mechanism with special reference to loess soil deposits. The collapse mechanism studies are summarized under three different categories, i.e. traditional approaches, microstructure approach, and soil mechanics-based approaches. The traditional and microstructure approaches for interpreting the collapse behavior are comprehensively summarized and critically reviewed based on the experimental results from the literature. The soil mechanics-based approaches proposed based on the experimental results of both compacted soils and natural loess soils are reviewed highlighting their strengths and limitations for estimating the collapse behavior. Simpler soil mechanics-based approaches with less parameters or parameters that are easy-to-determine from conventional tests are suggested for future research to better understand the collapse behavior of natural loess soils. Such studies would be more valuable for use in conventional geotechnical engineering practice applications.

  3. Application of Silicon Nitride (Si3N4 Ceramics in Ball Bearing

    Directory of Open Access Journals (Sweden)

    Wijianto Wijianto

    2016-08-01

    operation up to 1000°C, greater thermal shock resistance, lower density and low thermal expansion. This properties gives some benefit for ball bearing material such as higher running speed, reduce vibration of the shaft, will improve the life time and maintenance cost, lower heat generated, less energy consumption, lower wear rate, reducing noise level and reduce of using lubricant. The sintering methods are used to produce ball bearing from silicon nitride. Some techniques can be applied to increase ceramics strength which are reduce porosity, reduce grain size, reduce surface flaw and proof stressing. The surface finishing of the ceramic bearing is very important because silicon nitride as a brittle material, its strength is limited to the flaw sizes especially the flaw at the surface.

  4. A systematic study of ball passing frequencies based on dynamic modeling of rolling ball bearings with localized surface defects

    Science.gov (United States)

    Niu, Linkai; Cao, Hongrui; He, Zhengjia; Li, Yamin

    2015-11-01

    Ball passing frequencies (BPFs) are very important features for condition monitoring and fault diagnosis of rolling ball bearings. The ball passing frequency on outer raceway (BPFO) and the ball passing frequency on inner raceway (BPFI) are usually calculated by two well-known kinematics equations. In this paper, a systematic study of BPFs of rolling ball bearings is carried out. A novel method for accurately calculating BPFs based on a complete dynamic model of rolling ball bearings with localized surface defects is proposed. In the used dynamic model, three-dimensional motions, relative slippage, cage effects and localized surface defects are all considered. Moreover, localized surface defects are modeled accurately with consideration of the finite size of the ball, the additional clearance due to material absence, and changes of contact force directions. The reasonability of the proposed method for the prediction of dynamic behaviors of actual ball bearings with localized surface defects and for the calculation of BPFs is discussed by investigating the motion characteristics of a ball when it rolls through a defect. Parametric investigation shows that the shaft speed, external loads, the friction coefficient, raceway groove curvature factors, the initial contact angle, and defect sizes have great effects on BPFs. For a loaded ball bearing, the combination of rolling and sliding in contact region occurs, and the BPFs calculated by simple kinematical relationships are inaccurate, especially for high speed, low external load, and large initial contact angle conditions where severe skidding occurs. The hypothesis that the percentage variation of the spacing between impulses in a defective ball bearing was about 1-2% reported in previous investigations can be satisfied only for the conditions where the skidding effect in a bearing is slight. Finally, the proposed method is verified with two experiments.

  5. Wave function collapse implies divergence of average displacement

    OpenAIRE

    Marchewka, A.; Schuss, Z.

    2005-01-01

    We show that propagating a truncated discontinuous wave function by Schr\\"odinger's equation, as asserted by the collapse axiom, gives rise to non-existence of the average displacement of the particle on the line. It also implies that there is no Zeno effect. On the other hand, if the truncation is done so that the reduced wave function is continuous, the average coordinate is finite and there is a Zeno effect. Therefore the collapse axiom of measurement needs to be revised.

  6. A closed solution for the collapse load of pressurized pipelines in free spans

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Luciano M. [Brasilia Univ., DF (Brazil). Dept. de Engenharia Civil; Murray, David W.; Xuejun Song [University of Alberta (Canada). Civil Engineering Dept.

    2005-07-01

    Submarine pipelines for oil exploitation, generally, are under internal pressure and compressive thermal loading. Due to rough see-bottom terrains, these pipelines may be supported only intermittently and span freely. The collapse of such pipelines may produce oil leakage to the environment. A common engineering practice for the determination of the collapse load of such pipelines is the use of finite element modeling. This paper presents an analytical method for the determination of the collapse load of pressurized pipelines extended over free spans. The formulation also takes into account the internal pressure and initial imperfection, generally present in these pipelines. Collapse load is determined from a deduced transcendental equation. Results of the presented formulation are compared with sophisticated finite element analyses. While sophisticated finite element analysis requires hours of computer processing, the present formulation takes practically no time to assess a good approximation for the collapse load of pressurized free span pipelines under compression. The present paper is not intended to substitute the more precise finite element analyses but to provide an easier, faster, and practical way to determine a first approximation of the collapse load of pressurized free span pipelines. (author)

  7. Encapsulated Ball Bearings for Rotary Micro Machines

    Science.gov (United States)

    2007-01-01

    occurrence as well as the overall tribological properties of the bearing mechanism. Firstly, the number of stainless steel balls influences not only the load...stacks.iop.org/JMM/17/S224 Abstract We report on the first encapsulated rotary ball bearing mechanism using silicon microfabrication and stainless steel balls...The method of capturing stainless steel balls within a silicon race to support a silicon rotor both axially and radially is developed for rotary micro

  8. Mandibular Denture Base Deformation with Locator and Ball Attachments of Implant-Retained Overdentures.

    Science.gov (United States)

    ELsyad, Moustafa Abdou; Errabti, Hatem Mokhtar; Mustafa, Aisha Zakaria

    2016-12-01

    The aim of this in vitro study was to evaluate and compare mandibular denture base deformation between ball and Locator attachments of implant-retained overdentures. An experimental acrylic model covered with resilient silicone mucosal simulation was constructed. Two laboratory implants were placed in the canine areas of the model. Two duplicate experimental overdentures were constructed and connected to the implants with either ball (GI) or Locator (GII) attachments. To measure overdenture strain around the attachments, 3 strain gauges were attached to the lingual polished surface of the overdentures opposite to the right implant (loading side) 2 mm above the attachment level (Ch1), at the attachment level (Ch2), and 2 mm below the attachment level (Ch3). Another 3 gauges were bonded opposite to the left implant (non-loading side) in the same manner (Ch6, Ch7, and Ch8). To measure strain at the midline of the overdentures, two strain gauges were attached in the midline at 5 mm intervals (Ch4 and Ch5). A universal testing device was used to deliver vertical static load of 50 N unilaterally and bilaterally to the first molar area to measure strain using a multi-channel digital strain meter. During bilateral load application, GII recorded higher compressive strains than GI at the majority of channels. During unilateral load application, GI recorded higher tensile strains at Ch1, Ch2, and Ch3, and GII recorded higher strains than GI at Ch6, Ch7, and Ch8. During bilateral loading the highest strain was concentrated at Ch5 for both groups. During unilateral loading, the highest strain was concentrated at Ch2 for GI, and at Ch5 for GII. Ball attachments for implant-retained overdentures were associated with significant mandibular denture base deformation over the implants compared to Locator attachments. Therefore, denture base reinforcement may be recommended with ball attachmentz to increase fracture resistance of the base. © 2015 by the American College of

  9. Geophysical observations at cavity collapse

    Science.gov (United States)

    Jousset, Philippe; Bazargan-Sabet, Behrooz; Lebert, François; Bernardie, Séverine; Gourry, Jean-Christophe

    2010-05-01

    In Lorraine region (France) salt layers at about 200 meters depth are exploited by Solvay using solution mining methodology which consists in extracting the salt by dissolution, collapsing the cavern overburden during the exploitation phase and finally reclaiming the landscape by creating a water area. In this process, one of the main challenges for the exploiting company is to control the initial 120-m diameter collapse so as to minimize possible damages. In order to detect potential precursors and understand processes associated with such collapses, a wide series of monitoring techniques including micro seismics, broad-band seismology, hydro-acoustic, electromagnetism, gas probing, automatic leveling, continuous GPS, continuous gravity and borehole extensometry was set-up in the frame of an in-situ study carried out by the "Research Group for the Impact and Safety of Underground Works" (GISOS, France). Equipments were set-up well before the final collapse, giving a unique opportunity to analyze a great deal of information prior to and during the collapse process which has been successfully achieved on February the 13th, 2009 by controlling the cavity internal pressure. In this work, we present the results of data recorded by a network of 3 broadband seismometers, 2 accelerometers, 2 tilt-meters and a continuously gravity meter. We relate the variations of the brine pumping rate with the evolutions of the induced geophysical signals and finally we propose a first mechanical model for describing the controlled collapse. Beyond the studied case, extrapolation of the results obtained might contribute to the understanding of uncontrolled cavity collapses, such as pit-craters or calderas at volcanoes.

  10. Ball lightning. What nature is trying to tell the plasma research community

    International Nuclear Information System (INIS)

    Roth, J.R.

    1995-01-01

    Ball lightning has been extensively observed in atmospheric air, usually in association with thunderstorms, by untrained observers who were not in a position to make careful observations. These chance sightings have been documented by polling observers, who constitute perhaps 5% of the adult U.S. population. Unfortunately, ball lightning is not accessible to scientific analysis because it cannot be reproduced in the laboratory under controlled conditions. Natural ball lightning has been observed to last longer than 90 s and to have diameters from 1 cm to several meters. The energy density of a few lightning balls has been observed to be as high as 20000 J/cm 3 , well above the limit of chemical energy storage of, for example, TNT at 2000 J/cm 3 . Such observations suggest a plasma-related phenomenon with significant magnetic energy storage. If this is the case, ball lightning should have very interesting implications for fusion research, industrial plasma engineering, and military applications, as well as being of great theoretical and practical interest to the plasma research community. 20 refs., 15 figs., 2 tabs

  11. Spherical collapse in quintessence models with zero speed of sound

    CERN Document Server

    Creminelli, Paolo; Noreña, Jorge; Senatore, Leonardo; Vernizzi, Filippo

    2010-01-01

    We study the spherical collapse model in the presence of quintessence with zero speed of sound. This case is particularly motivated for w<-1 as it is required by stability. As pressure gradients are negligible, quintessence follows dark matter during the collapse. The spherical overdensity behaves as a separate closed FLRW universe, so that its evolution can be studied exactly. We derive the critical overdensity for collapse and we use the extended Press-Schechter theory to study how the clustering of quintessence affects the dark matter mass function. The effect is dominated by the modification of the linear dark matter growth function. A larger effect occurs on the total mass function, which includes the quintessence overdensities. Indeed, here quintessence constitutes a third component of virialized objects, together with baryons and dark matter, and contributes to the total halo mass by a fraction ~ (1+w) Omega_Q / Omega_m. This gives a distinctive modification of the total mass function at low redshif...

  12. Initial non-weight-bearing therapy is important for preventing vertebral body collapse in elderly patients with clinical vertebral fractures

    Directory of Open Access Journals (Sweden)

    Kishikawa Y

    2012-04-01

    Full Text Available Yoichi KishikawaKishikawa Orthopaedic Clinic, Saga City, Saga, JapanPurpose: The aim of the present conventional observational study was to compare the clinical outcomes of initial non-weight-bearing therapy and conventional relative rest therapy among elderly patients with clinical vertebral fractures.Methods: In total, 196 consecutive patients with clinical vertebral fractures (mean age: 78 years who were hospitalized for treatment between January 1999 and March 2007 were analyzed. Initial non-weight-bearing therapy consisted of complete bed rest allowing rolling on the bed without any weight-bearing to the spine for 2 weeks, followed by rehabilitation wearing a soft brace. The indications for initial non-weight-bearing therapy were vertebral fracture involving the posterior portion of the vertebral body at the thoraco-lumbar spine, mild neurological deficit, instability of the fracture site, severe pain, multiple vertebral fractures arising from trauma, malalignment at the fracture site, and mild spinal canal stenosis caused by the fracture. Patients who met the indication criteria were treated with initial non-weight-bearing therapy (n = 103, while the other patients were treated with conventional relative rest (n = 93. All the patients were uniformly treated with intramuscular elcatonin to relieve pain. The primary endpoint was progression of the vertebral fracture. The secondary endpoints included bony union and subjective back pain. The follow-up period was 12 weeks.Results: Compared with the conventional relative rest group, the collapse rate of the anterior and posterior portions of the vertebral body was significantly smaller in the initial non-weight-bearing group. The bony union rate was 100% in the initial non-weight-bearing group and 97% in the conventional relative rest group. The number of patients who experienced back pain was significantly lower in the initial non-weight-bearing group than in the conventional relative rest

  13. Automatic lung segmentation in the presence of alveolar collapse

    Directory of Open Access Journals (Sweden)

    Noshadi Areg

    2017-09-01

    Full Text Available Lung ventilation and perfusion analyses using chest imaging methods require a correct segmentation of the lung to offer anatomical landmarks for the physiological data. An automatic segmentation approach simplifies and accelerates the analysis. However, the segmentation of the lungs has shown to be difficult if collapsed areas are present that tend to share similar gray values with surrounding non-pulmonary tissue. Our goal was to develop an automatic segmentation algorithm that is able to approximate dorsal lung boundaries even if alveolar collapse is present in the dependent lung areas adjacent to the pleura. Computed tomography data acquired in five supine pigs with injured lungs were used for this purpose. First, healthy lung tissue was segmented using a standard 3D region growing algorithm. Further, the bones in the chest wall surrounding the lungs were segmented to find the contact points of ribs and pleura. Artificial boundaries of the dorsal lung were set by spline interpolation through these contact points. Segmentation masks of the entire lung including the collapsed regions were created by combining the splines with the segmentation masks of the healthy lung tissue through multiple morphological operations. The automatically segmented images were then evaluated by comparing them to manual segmentations and determining the Dice similarity coefficients (DSC as a similarity measure. The developed method was able to accurately segment the lungs including the collapsed regions (DSCs over 0.96.

  14. Entanglement and the three-dimensionality of the Bloch ball

    Energy Technology Data Exchange (ETDEWEB)

    Masanes, Ll., E-mail: ll.masanes@gmail.com [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Müller, M. P. [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany); Pérez-García, D. [Departamento de Analisis Matematico and IMI, Universidad Complutense de Madrid, 28040 Madrid (Spain); Augusiak, R. [ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona (Spain)

    2014-12-15

    We consider a very natural generalization of quantum theory by letting the dimension of the Bloch ball be not necessarily three. We analyze bipartite state spaces where each of the components has a d-dimensional Euclidean ball as state space. In addition to this, we impose two very natural assumptions: the continuity and reversibility of dynamics and the possibility of characterizing bipartite states by local measurements. We classify all these bipartite state spaces and prove that, except for the quantum two-qubit state space, none of them contains entangled states. Equivalently, in any of these non-quantum theories, interacting dynamics is impossible. This result reveals that “existence of entanglement” is the requirement with minimal logical content which singles out quantum theory from our family of theories.

  15. Current status of relativistic core collapse simulations

    Energy Technology Data Exchange (ETDEWEB)

    Font, Jose A [Departamento de Astronomia y Astrofisica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot (Valencia) (Spain)

    2007-05-15

    With the first generation of ground-based gravitational wave laser interferometers already taking data, the availability of reliable waveform templates from astrophysical sources, which may help extract the signal from the anticipated noisy data, is urgently required. Gravitational stellar core collapse supernova has traditionally been considered among the most important astrophysical sources of potentially detectable gravitational radiation. Only very recently the first multidimensional simulations of relativistic rotational core collapse have been possible (albeit for models with simplified input physics), thanks to the use of conservative formulations of the hydrodynamics equations and advanced numerical methodology, as well as stable formulations of Einstein's equations. In this paper, the current status of relativistic core collapse simulations is discussed, with the emphasis given to the modelling of the collapse dynamics and to the computation of the gravitational radiation in the existing numerical approaches. Work employing the conformally-flat approximation (CFC) of the 3+1 Einstein's equations is reported, as well as extensions of this approximation (CFC+) and investigations within the framework of the so-called BSSN formulation of the 3+1 gravitational field equations (with no approximation for the spacetime dynamics). On the other hand, the incorporation of magnetic fields and the MHD equations in numerical codes to improve the realism of core collapse simulations in general relativity, is currently an emerging field where significant progress is bound to be soon achieved. The paper also contains a brief discussion of magneto-rotational simulations of core collapse, aiming at addressing the effects of magnetic fields on the collapse dynamics and on the gravitational waveforms.

  16. Current status of relativistic core collapse simulations

    International Nuclear Information System (INIS)

    Font, Jose A

    2007-01-01

    With the first generation of ground-based gravitational wave laser interferometers already taking data, the availability of reliable waveform templates from astrophysical sources, which may help extract the signal from the anticipated noisy data, is urgently required. Gravitational stellar core collapse supernova has traditionally been considered among the most important astrophysical sources of potentially detectable gravitational radiation. Only very recently the first multidimensional simulations of relativistic rotational core collapse have been possible (albeit for models with simplified input physics), thanks to the use of conservative formulations of the hydrodynamics equations and advanced numerical methodology, as well as stable formulations of Einstein's equations. In this paper, the current status of relativistic core collapse simulations is discussed, with the emphasis given to the modelling of the collapse dynamics and to the computation of the gravitational radiation in the existing numerical approaches. Work employing the conformally-flat approximation (CFC) of the 3+1 Einstein's equations is reported, as well as extensions of this approximation (CFC+) and investigations within the framework of the so-called BSSN formulation of the 3+1 gravitational field equations (with no approximation for the spacetime dynamics). On the other hand, the incorporation of magnetic fields and the MHD equations in numerical codes to improve the realism of core collapse simulations in general relativity, is currently an emerging field where significant progress is bound to be soon achieved. The paper also contains a brief discussion of magneto-rotational simulations of core collapse, aiming at addressing the effects of magnetic fields on the collapse dynamics and on the gravitational waveforms

  17. Inter and Intra Positional Differences in Ball Kicking Between U-16 Croatian Soccer Players

    Directory of Open Access Journals (Sweden)

    Ante Rađa

    2016-09-01

    Full Text Available The main goal of this research was to determine inter and intra positional differences in ball kicking speed between U-16 Croatian soccer players. 44 young soccer players (15.7 ± 1.5 years were tested with 8 specific soccer field tests that evaluate kicking velocity by using Pocket radar that was reading the ball velocity in km/h. The tests took place two days in a row; beginning at 8 A.M. Prior to the tests, players warmed up and stretched for 20 minutes (13 minutes of running with and without the ball, 7 minutes of dynamic stretching. Inter positional differences were significant (p ≤ 0.05 between midfielders and defenders in all tests and in one test midfielders scored better than strikers. The fastest kicks were instep kicks when stationary and non-stationary ball was kicked. Shots were taken by midfielders with 106.94±7.07 and 101.61±7.88 km/h respectively. Similar to dominant leg, midfielders also achieved the fastest instep kicks with non-dominant leg (91.44±9.56 km/h. Intra positional differences revealed that soccer kick velocity is one of possible selection tools, because more efficient players in all playing lines shoot faster kicks than less efficient players.

  18. Generalized isoperimetric inequalities for extrinsic balls in minimal submanifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, Vicente

    2002-01-01

    The volume of an extrinsic ball in a minimal submanifold has a well defined lower bound when the ambient manifold has an upper bound on its sectional curvatures, see e.g. [2] and [10]. When this upper bound is non-positive, the second named author has shown an isoperimetric inequality for such do...

  19. Coal ball formation and a soil extinction near the P-Tr boundary

    Science.gov (United States)

    Breecker, D.; Royer, D. L.

    2017-12-01

    Coal balls are calcium carbonate accumulations that commonly permineralize paleotropical PermoCarboniferous coal deposits and preserve exceptional specimens of the coal swamp flora. A widely applicable model for the origin of coal balls is lacking despite the study of these deposits for over a century. Two characteristics of coal balls have been particularly challenging to explain: 1) their temporal range is restricted to the PermoCarboniferous and 2) their typical oxygen isotope and elemental compositions paradoxically indicate freshwater and marine origins, respectively. We propose a new model for coal ball formation. The first step in our model is the episodic delivery of seawater and marine carbonate sediment to coastal mires. Next, these waters are diluted by freshwater and the carbonates dissolve at the elevated pCO2 of the mire subsurface. Finally, as waters flow laterally through stands of arborescent lycopsids, aqueous CO2 in the pore spaces of the peat escapes by diffusion through the air-filled lycopsid rootlets into the overlying water column, where some rootlets are thought to have extended. The CO2 escape drives calcite precipitation in the soil zone. This model explains the narrow temporal occurrence of coal balls, which coincides with the peak diversity of arborescent lycopsids. It also resolves the geochemical conundrum; dilution by freshwater can result in relatively low pore water δ18O values without preventing high-Mg calcite formation. Furthermore, we show mathematically that for published densities of arborescent lycopsid root mats and for reasonable rates of lateral water flow and vertical peat accumulation, CO2 could escape rapidly enough through the rootlets to fill >35% of the porosity with calcite before substantial burial (top several decimeters of peat), explaining the exceptional preservation of coal swamp flora. Therefore, we suggest that coal balls are pedogenic in origin and that their disappearance from the rock record represents

  20. Q-balls in flat potentials

    International Nuclear Information System (INIS)

    Copeland, Edmund J.; Tsumagari, Mitsuo I.

    2009-01-01

    We study the classical and absolute stability of Q-balls in scalar field theories with flat potentials arising in both gravity-mediated and gauge-mediated models. We show that the associated Q-matter formed in gravity-mediated potentials can be stable against decay into their own free particles as long as the coupling constant of the nonrenormalizable term is small, and that all of the possible three-dimensional Q-ball configurations are classically stable against linear fluctuations. Three-dimensional gauge-mediated Q-balls can be absolutely stable in the thin-wall limit, but are completely unstable in the thick-wall limit.

  1. PSI collapse and relativistic covariance

    International Nuclear Information System (INIS)

    Costa de Beauregard, Olivier

    1980-01-01

    We call macrorelativistic a theory invariant under the orthochronous Lorentz group and obeying the 'factlike' principle of retarded causality, and microrelativistic a theory invariant under the full Lorentz group and CPT symmetric. The Einstein correlations either direct (non-separability of measurements issuing from a common preparation) or reversed (non-separability of preparations producing a common measurement) are incompatible with the macro-, but compatible with the microrelativity. We assume that fundamental physics is fully Lorentz and CPT invariant (the transition to macrophysics introducing a 'factlike asymmetry) and consequently define the collapse-and-retrocollapse concept [fr

  2. Sonographic Analysis of the Collapsed Gall Bladder

    International Nuclear Information System (INIS)

    Han, Sang Suk; Choi, Jae Young; Choi, Seok Jin; Eun, Chung Ki; Nam, Kyung Jin; Lee, Jeong Mi

    1996-01-01

    This study was done to find answers for further following questions in cases of the collapsed gallbladder (GB) : What is the probability of the presence of stone when stony echo is visible in GB area? What is the probability of the presence of stone when only acoustic shadow is visible from GB area? What are the associated GB pathologies except stone or cholecystitis in previously mentioned situations and is it possible to differentiate them? What are the underlying pathologies of GB collapse without stony echo or acoustic shadow and is it possible to differentiate them sonographic ally? What are the rate and causes of re-expansion of the collapsed GB on follow-up study? Prospective study was done in 157 cases of collapsed GB with no visible or nearly no visible bile filled lumen in recent 3 years. Sonographic analysis for GB lesions was done in 61 confirmed cases. Changing pattern of GB lumen on follow-up study and their underlying pathologies were analyzed in 28 cases. Initial sonographic examination was done with 3 or 3.5 MHz transducer. No other transducer was used in cases showing stony echo or acoustic shadow in GB area, but additional examination was done with 5 or 7-4 MHz transducer in cases without stony echo or acoustic shadow. Among 31 cases, which showed stony echo, stone was found in 30 cases and milk of calcium bile in one case. Stone was present in all of the 11 cases which showed only acoustic shadow from the collapsed GB without stony echo. GB cancer was accompanied in 2 cases among upper 42 cases, and its possibility could be suspected sonographic ally. Underlying pathologies of the 19cases without stony echo or acoustic shadow were as follows : GB stone (3), cholecystitis (6), GB cancer (1), bile plug syndrome (1), hepatitis (5), and ascites (3). And sonographic differentiation of the underlying causes for the collapse was possible in only 1 case of GB cancer. Among 28 cases of the follow-up study, 20 cases showed re-expansion of the GB lumen and

  3. Anomalous polymer collapse winding angle distributions

    Science.gov (United States)

    Narros, A.; Owczarek, A. L.; Prellberg, T.

    2018-03-01

    In two dimensions polymer collapse has been shown to be complex with multiple low temperature states and multi-critical points. Recently, strong numerical evidence has been provided for a long-standing prediction of universal scaling of winding angle distributions, where simulations of interacting self-avoiding walks show that the winding angle distribution for N-step walks is compatible with the theoretical prediction of a Gaussian with a variance growing asymptotically as Clog N . Here we extend this work by considering interacting self-avoiding trails which are believed to be a model representative of some of the more complex behaviour. We provide robust evidence that, while the high temperature swollen state of this model has a winding angle distribution that is also Gaussian, this breaks down at the polymer collapse point and at low temperatures. Moreover, we provide some evidence that the distributions are well modelled by stretched/compressed exponentials, in contradistinction to the behaviour found in interacting self-avoiding walks. Dedicated to Professor Stu Whittington on the occasion of his 75th birthday.

  4. Workplace safety in Bangladesh ready-made garment sector: 3 years after the Rana Plaza collapse.

    Science.gov (United States)

    Barua, Uttama; Ansary, Mehedi Ahmed

    2017-12-01

    Workplace safety is one of the most important issues in industries worldwide, and is endangered by industrial accidents. Different industrial disasters have resulted in several initiatives worldwide to protect human life and reduce material damage, both nationally and internationally. In Bangladesh, the ready-made garment (RMG) industry is one of the most important export-oriented business sectors, which is facing challenges to ensure workplace safety. The Rana Plaza collapse in Bangladesh is the consequence of such non-compliance. The accident resulted in different local and global initiatives to address the challenges. This article reviews progress and achievement of the initiatives to reduce vulnerability in the Bangladesh RMG industry within 3 years after the deadly accident. In the long run, the challenge is to maintain momentum already created for achieving sustainability in the RMG sector in Bangladesh and maintaining compliance even after the end of support from external partners.

  5. 2D and 3D core-collapse supernovae simulation results obtained with the CHIMERA code

    Energy Technology Data Exchange (ETDEWEB)

    Bruenn, S W; Marronetti, P; Dirk, C J [Physics Department, Florida Atlantic University, 777 W. Glades Road, Boca Raton, FL 33431-0991 (United States); Mezzacappa, A; Hix, W R [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 (United States); Blondin, J M [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Messer, O E B [Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 (United States); Yoshida, S, E-mail: bruenn@fau.ed [Max-Planck-Institut fur Gravitationsphysik, Albert Einstein Institut, Golm (Germany)

    2009-07-01

    Much progress in realistic modeling of core-collapse supernovae has occurred recently through the availability of multi-teraflop machines and the increasing sophistication of supernova codes. These improvements are enabling simulations with enough realism that the explosion mechanism, long a mystery, may soon be delineated. We briefly describe the CHIMERA code, a supernova code we have developed to simulate core-collapse supernovae in 1, 2, and 3 spatial dimensions. We then describe the results of an ongoing suite of 2D simulations initiated from a 12, 15, 20, and 25 M{sub o-dot} progenitor. These have all exhibited explosions and are currently in the expanding phase with the shock at between 5,000 and 20,000 km. We also briefly describe an ongoing simulation in 3 spatial dimensions initiated from the 15 M{sub o-dot} progenitor.

  6. A study on a new algorithm to optimize ball mill system based on modeling and GA

    International Nuclear Information System (INIS)

    Wang Heng; Jia Minping; Huang Peng; Chen Zuoliang

    2010-01-01

    Aiming at the disadvantage of conventional optimization method for ball mill pulverizing system, a novel approach based on RBF neural network and genetic algorithm was proposed in the present paper. Firstly, the experiments and measurement for fill level based on vibration signals of mill shell was introduced. Then, main factors which affected the power consumption of ball mill pulverizing system were analyzed, and the input variables of RBF neural network were determined. RBF neural network was used to map the complex non-linear relationship between the electric consumption and process parameters and the non-linear model of power consumption was built. Finally, the model was optimized by genetic algorithm and the optimal work conditions of ball mill pulverizing system were determined. The results demonstrate that the method is reliable and practical, and can reduce the electric consumption obviously and effectively.

  7. Reverse martensitic transformation in alumina-15 vol% zirconia nanostructured powder synthesized by high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Maneshian, M.H. [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)], E-mail: mh_maneshian@yahoo.com; Banerjee, M.K. [National Institute of Foundry and Forge Technology, Hatia, Ranchi 834003 (India)

    2008-07-14

    In the present work, three alumina-15 vol% zirconia composites with Y{sub 2}O{sub 3}, MgO as dopants and without oxide as dopant have been investigated. High energy ball milling (HEBM) provides the positive thermodynamic driving force for monoclinic to tetragonal transformation and it reduces starting temperature for the reverse martensitic transformation, meanwhile mobility of zirconium cations and oxygen anions are enhanced in zirconia by HEBM. The general, albeit heuristic, reasoning is corroborated by nanocrystallity, particle size and also the retained monoclinic seem to play an important role. After 10 h HEBM, approximately 28% zirconia tetragonal phase is achieved. Non-stoichiometric tetragonal zirconia phase; Zr{sub 0.95}O{sub 2} is seen to have been achieved by high energy ball milling (HEBM). The structural and compositional evolutions during HEBM have been investigated using X-ray diffraction method (XRD) and scanning electron microscopy (SEM). High resolution transmission electron microscope (TEM) is also used for further understanding about the phenomenological changes taking place during high energy ball milling.

  8. LHC gets the ball rolling

    CERN Multimedia

    2007-01-01

    1. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI).2. During the tests the ball is inserted very carefully into the vacuum chamber.1. Le groupe pluridisciplinaire qui a mené le projet de balle RF pour vérifier les interconnexions avec, de gauche à droite, Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS) et Marek Gasior (AB/BI).2. Lors des tests, la balle est insérée dans la chambre à vide avec beaucoup de précaution.

  9. Collapse of white dwarfs in low mass binary systems

    International Nuclear Information System (INIS)

    Isern, J.; Canal, R.; Garcia-Berro, E.; Hernanz, M.; Labay, J.

    1987-01-01

    Low-mass binary X-ray sources and cataclysmic variables are composed of a compact star plus a non-degenerate star with a mass of the order of 1 M sun . In the first case, the degenerate star is a neutron star. In the second case, the star is a white dwarf. The similarities of both systems are so high that it is worthwhile to look for the possibility of obtaining a neutron star from the collapse of a white dwarf that accretes matter. The present work shows that massive, initially cold white dwarfs can collapse non-explosively if they accrete mass at a rate greater than 1.0E-7 M sun per year. (Author)

  10. Interfacial free energy governs single polystyrene chain collapse in water and aqueous solutions.

    Science.gov (United States)

    Li, Isaac T S; Walker, Gilbert C

    2010-05-12

    The hydrophobic interaction is significantly responsible for driving protein folding and self-assembly. To understand it, the thermodynamics, the role of water structure, the dewetting process surrounding hydrophobes, and related aspects have undergone extensive investigations. Here, we examine the hypothesis that polymer-solvent interfacial free energy is adequate to describe the energetics of the collapse of a hydrophobic homopolymer chain at fixed temperature, which serves as a much simplified model for studying the hydrophobic collapse of a protein. This implies that changes in polymer-solvent interfacial free energy should be directly proportional to the force to extend a collapsed polymer into a bad solvent. To test this hypothesis, we undertook single-molecule force spectroscopy on a collapsed, single, polystyrene chain in water-ethanol and water-salt mixtures where we measured the monomer solvation free energy from an ensemble average conformations. Different proportions within the binary mixture were used to create solvents with different interfacial free energies with polystyrene. In these mixed solvents, we observed a linear correlation between the interfacial free energy and the force required to extend the chain into solution, which is a direct measure of the solvation free energy per monomer on a single chain at room temperature. A simple analytical model compares favorably with the experimental results. This knowledge supports a common assumption that explicit water solvent may not be necessary for cases whose primary concerns are hydrophobic interactions and hydrophobic hydration.

  11. General relativistic collapse of rotating stars

    International Nuclear Information System (INIS)

    Nakamura, T.

    1984-01-01

    When a rotating star begins to collapse, the gravity becomes so strong that there appears a region from which even a photon cannot escape. After the distortion of space-time is radiated as gravitational waves, a Kerr black hole is formed finally. One of the main goals for numerical relativity is to simulate the collapse of a rotating star under realistic conditions. However, to know both the dynamics of matter and the propagation of gravitational radiation seems to be very difficult. Therefore, in this paper the problem is divided into 4 stages. They are: (1) The time evolution of pure gravitational waves is calculated in a 2-D code. (2) In this stage, the author tries to understand the dynamics of a collapsing, rotating star in 2D code. (3) Combining the techniques from stages 1, 2, the author tries to know both the dynamics of matter and the propagation of gravitational waves generated by the nonspherical motion of matter. (4) The author simulates the gravitational collapse of a rotating star to a black hole in 3D. 25 references, 12 figures, 1 table

  12. Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

    Energy Technology Data Exchange (ETDEWEB)

    Boss, Alan P., E-mail: aboss@carnegiescience.edu [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

    2017-08-01

    Recent meteoritical analyses support an initial abundance of the short-lived radioisotope (SLRI) {sup 60}Fe that may be high enough to require nucleosynthesis in a core-collapse supernova, followed by rapid incorporation into primitive meteoritical components, rather than a scenario where such isotopes were inherited from a well-mixed region of a giant molecular cloud polluted by a variety of supernovae remnants and massive star winds. This paper continues to explore the former scenario, by calculating three-dimensional, adaptive mesh refinement, hydrodynamical code (FLASH 2.5) models of the self-gravitational, dynamical collapse of a molecular cloud core that has been struck by a thin shock front with a speed of 40 km s{sup −1}, leading to the injection of shock front matter into the collapsing cloud through the formation of Rayleigh–Taylor fingers at the shock–cloud intersection. These models extend the previous work into the nonisothermal collapse regime using a polytropic approximation to represent compressional heating in the optically thick protostar. The models show that the injection efficiencies of shock front materials are enhanced compared to previous models, which were not carried into the nonisothermal regime, and so did not reach such high densities. The new models, combined with the recent estimates of initial {sup 60}Fe abundances, imply that the supernova triggering and injection scenario remains a plausible explanation for the origin of the SLRIs involved in the formation of our solar system.

  13. Influence of cation disorder on the magnetic properties of ball-milled ilmenite (FeTiO3)

    DEFF Research Database (Denmark)

    Mørup, Steen; Rasmussen, Helge Kildahl; Brok, Erik

    2012-01-01

    We have investigated the evolution of crystal structure, cation disorder and magnetic properties of ilmenite (FeTiO3) after increasing time of high-energy ball-milling in an inert atmosphere. Refinement of X-ray diffraction data show that the hexagonal crystal structure of ilmenite is maintained...

  14. Physics of collapses. Probabilistic occurrence of ELMs and crashes

    International Nuclear Information System (INIS)

    Itoh, S.-I.; Toda, S.; Yagi, M.; Itoh, K.; Fukuyama, A.

    1997-01-01

    Statistical picture for the collapse is proposed. The physics picture of the crash phenomena, which is based on the turbulence-turbulence transition, is extended to include the statistical variance of observables. The dynamics of the plasma gradient and the turbulence level is studied, with the hysteresis nature in the flux-gradient relation. The probabilistic excitation is predicted. The critical condition is described by the statistical probability. (author)

  15. COLLAPSE AND FRAGMENTATION OF MAGNETIC MOLECULAR CLOUD CORES WITH THE ENZO AMR MHD CODE. I. UNIFORM DENSITY SPHERES

    International Nuclear Information System (INIS)

    Boss, Alan P.; Keiser, Sandra A.

    2013-01-01

    Magnetic fields are important contributors to the dynamics of collapsing molecular cloud cores, and can have a major effect on whether collapse results in a single protostar or fragmentation into a binary or multiple protostar system. New models are presented of the collapse of magnetic cloud cores using the adaptive mesh refinement code Enzo2.0. The code was used to calculate the ideal magnetohydrodynamics (MHD) of initially spherical, uniform density, and rotation clouds with density perturbations, i.e., the Boss and Bodenheimer standard isothermal test case for three-dimensional (3D) hydrodynamics codes. After first verifying that Enzo reproduces the binary fragmentation expected for the non-magnetic test case, a large set of models was computed with varied initial magnetic field strengths and directions with respect to the cloud core axis of rotation (parallel or perpendicular), density perturbation amplitudes, and equations of state. Three significantly different outcomes resulted: (1) contraction without sustained collapse, forming a denser cloud core; (2) collapse to form a single protostar with significant spiral arms; and (3) collapse and fragmentation into binary or multiple protostar systems, with multiple spiral arms. Comparisons are also made with previous MHD calculations of similar clouds with a barotropic equations of state. These results for the collapse of initially uniform density spheres illustrate the central importance of both magnetic field direction and field strength for determining the outcome of dynamic protostellar collapse.

  16. Static Load Distribution in Ball Bearings

    Science.gov (United States)

    Ricci, Mario

    2010-01-01

    A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

  17. Development of hemipenes in the ball python snake Python regius.

    Science.gov (United States)

    Leal, Francisca; Cohn, Martin J

    2015-01-01

    Within amniotes, external copulatory organs have undergone extensive morphological diversification. One of the most extreme examples is squamate (lizards and snakes) hemipenes, which are paired copulatory organs that extend from the lateral margins of the cloaca. Here, we describe the development of hemipenes in a basal snake, the ball python (Python regius). Snake hemipenes arise as a pair of lateral swellings on either side of the caudal part of the cloaca, and these paired outgrowths persist to form the left and right hemipenes. In non-squamate amniotes, external genitalia form from paired swellings that arise on the anterior side of the cloaca, which then fuse medially to form a single genital tubercle, the anlagen of the penis or clitoris. Whereas in non-squamate amniotes, Sonic hedgehog (Shh)-expressing cells of the cloacal endoderm form the urethral or sulcus epithelium and are required for phallus outgrowth, the hemipenes of squamates lack an endodermal contribution, and the sulcus does not express Shh. Thus, snake hemipenes differ from the genital tubercles of non-squamate amniotes both in their embryonic origins and in at least part of patterning mechanisms, which raises the possibility that hemipenes may not be direct homologs of the unpaired amniote penis. Nonetheless, we find that some developmental genes show similar expression patterns in snake hemipenes buds and non-squamate genital tubercles, suggesting that homologous developmental mechanisms are involved in aspects of external genital development across amniotes, even when these structures may have different developmental origins and may have arisen independently during evolution.

  18. Multifractal properties of ball milling dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Budroni, M. A., E-mail: mabudroni@uniss.it; Pilosu, V.; Rustici, M. [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, Via Vienna 2, Sassari 07100 (Italy); Delogu, F. [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, Cagliari 09123 (Italy)

    2014-06-15

    This work focuses on the dynamics of a ball inside the reactor of a ball mill. We show that the distribution of collisions at the reactor walls exhibits multifractal properties in a wide region of the parameter space defining the geometrical characteristics of the reactor and the collision elasticity. This feature points to the presence of restricted self-organized zones of the reactor walls where the ball preferentially collides and the mechanical energy is mainly dissipated.

  19. Optimum condition determination of Rirang uranium ores grinding using ball mill

    International Nuclear Information System (INIS)

    Affandi, Kosim; Waluyo, Sugeng; Sarono, Budi; Sujono; Muhammad

    2002-01-01

    The grinding experiment on Rirang Uranium ore has been carried out with the aim is to find out the optimum condition of wet grinding using ball mill to produce particle size -325, -200 and -100 mesh. This will be used for decomposition feed the test was done by examine the parameters comparison of ore's weight against ball's weight and time of grinding. The test shown that the product of particle size -325 meshes was achieved optimum condition at the comparison ore's weight: ball = 1:3, grinding time 150 minutes, % solid 60, speed rotation of ball mill 60 rpm and recovery of grinding was 93.51 % of -325 mesh. The product of particle size -200 mesh was achieved optimum condition at comparison ore's weight: ball = 1:2, time of grinding 60 minutes, the fraction of + 200 mesh was regrind, the recovery of grinding 6.82% at particle size of (-200 + 250) mesh, 5.75 % at (-250 + 325)m mesh and, 47.93 % -325 mesh. The product of particle size -100 mesh was achieved the optimum condition at comparison ore's weight: ball = 1:2, time of grinding at 30 minutes particle size +100 mesh regrinding using mortar grinder, recovery of grinding 30.10% at particle size (-100 + 150) m, 12.28 % at (-150 + 200) mesh, 15.92 % at (-200 + 250) mesh, 12.44 % at (-250 + 325) mesh and 29.26 % -325 mesh. The determination of specific gravity of Rirang uranium ore was between 4.15 - 4.55 g/cm 3

  20. Gravitational radiation from stellar collapse: The initial burst

    International Nuclear Information System (INIS)

    Shapiro, S.L.

    1977-01-01

    The burst of gravitational radiation emitted during the initial collapse and rebound of a homogeneous, uniformly rotating spheroid with internal pressure is analyzed numerically. The surface of the collapsing spheroid is assumed to start at rest from infinity with negligible eccentricity (''zero-energy collapse''). The adopted internal pressure function is constant on self-similar spheroidal surfaces, and its central value is described by a polytropic law with index n< or =3. The Newtonian equations of motion are integrated numerically to follow the initial collapse and rebound of the configuration for the special case in which the collapse is time-reversal invariant about the moment of maximum compression, and the total energy and frequency spectrum of the emitted quadrupole radiation are computed. The results are employed to estimate the (approx.minimum) total energy and frequency distribution of the initial burst of gravitational radiation emitted during the formation of low-mass (Mapproximately-less-thanM/sub sun/) neutron stars and during the collapse of supermassive gas clouds

  1. Contribution of Visual Information about Ball Trajectory to Baseball Hitting Accuracy.

    Directory of Open Access Journals (Sweden)

    Takatoshi Higuchi

    Full Text Available The contribution of visual information about a pitched ball to the accuracy of baseball-bat contact may vary depending on the part of trajectory seen. The purpose of the present study was to examine the relationship between hitting accuracy and the segment of the trajectory of the flying ball that can be seen by the batter. Ten college baseball field players participated in the study. The systematic error and standardized variability of ball-bat contact on the bat coordinate system and pitcher-to-catcher direction when hitting a ball launched from a pitching machine were measured with or without visual occlusion and analyzed using analysis of variance. The visual occlusion timing included occlusion from 150 milliseconds (ms after the ball release (R+150, occlusion from 150 ms before the expected arrival of the launched ball at the home plate (A-150, and a condition with no occlusion (NO. Twelve trials in each condition were performed using two ball speeds (31.9 m·s-1 and 40.3 m·s-1. Visual occlusion did not affect the mean location of ball-bat contact in the bat's long axis, short axis, and pitcher-to-catcher directions. Although the magnitude of standardized variability was significantly smaller in the bat's short axis direction than in the bat's long axis and pitcher-to-catcher directions (p < 0.001, additional visible time from the R+150 condition to the A-150 and NO conditions resulted in a further decrease in standardized variability only in the bat's short axis direction (p < 0.05. The results suggested that there is directional specificity in the magnitude of standardized variability with different visible time. The present study also confirmed the limitation to visual information is the later part of the ball trajectory for improving hitting accuracy, which is likely due to visuo-motor delay.

  2. Non-Fermi liquid behaviour in an extended Anderson model

    International Nuclear Information System (INIS)

    Liu Yuliang; Su Zhaobin; Yu Lu.

    1996-08-01

    An extended Anderson model, including screening channels (non-hybridizing, but interacting with the local orbit), is studied within the Anderson-Yuval approach, originally devised for the single-chanell Kondo problem. By comparing the perturbation expansions of this model and a generalized resonant level model, the spin-spin correlation functions are calculated which show non-Fermi liquid exponent depending on the strength of the scattering potential. The relevance of this result to experiments in some heavy fermion systems is briefly discussed. (author). 31 refs

  3. Preparation of tungsten-iron carbide by ball milling

    International Nuclear Information System (INIS)

    Wang, G.M.; Campbell, S.J.; Calka, A.; Kaczmarek, W.A.

    1996-01-01

    Several sets of elemental powder mixtures of Fe-W-C (W 46 Fe 46 C 8 , W 60 Fe 20 C 20 and W 34 Fe 33 C 33 ) were ball milled using Uni-Ball mill for periods of up to 550 h in vacuum with a ball - to - powder ratio of about 35:1. Depending on the milling time, the main component of the as-milled materials was found to be solid solutions of Fe-W-C or Fe-C. Ternary phase W 3 Fe 3 C was obtained on annealing the as-milled materials at about 700 deg C. This product was then found to transfer to (FeW) 6 C on heat treatment at about 800 deg C. The resultant products of the annealing processes were found to depend not only on the annealing temperature, but also the starting composition, especially the initial carbon concentration. Detailed information on the structural and phase evolution during thermal treatment as measured using x-ray diffraction, Moessbauer spectroscopy and thermal analysis is presented. Special interest is focused on the competition for formation in this system between the Fe-C, W-Fe and W-C phases

  4. Three-dimensional simulations of rapidly rotating core-collapse supernovae: finding a neutrino-powered explosion aided by non-axisymmetric flows

    Science.gov (United States)

    Takiwaki, Tomoya; Kotake, Kei; Suwa, Yudai

    2016-09-01

    We report results from a series of three-dimensional (3D) rotational core-collapse simulations for 11.2 and 27 M⊙ stars employing neutrino transport scheme by the isotropic diffusion source approximation. By changing the initial strength of rotation systematically, we find a rotation-assisted explosion for the 27 M⊙ progenitor , which fails in the absence of rotation. The unique feature was not captured in previous two-dimensional (2D) self-consistent rotating models because the growing non-axisymmetric instabilities play a key role. In the rapidly rotating case, strong spiral flows generated by the so-called low T/|W| instability enhance the energy transport from the proto-neutron star (PNS) to the gain region, which makes the shock expansion more energetic. The explosion occurs more strongly in the direction perpendicular to the rotational axis, which is different from previous 2D predictions.

  5. 3D Results in VTK with data for gravitational collapse of a molecular hydrogen cloud

    International Nuclear Information System (INIS)

    Duarte P, R.; Klapp E, J.

    2007-01-01

    With the objective of using free software for visualization, we experience with VTK (Visualization Toolkit) system guided to objects, using a VTK classes library, Tcl languages and PV-WAVE, to create an application and to produce some images in 3D with data of 3D coordinated points, in this case of a gravitational collapse of a cloud of molecular hydrogen. (Author)

  6. Apparatus Would Measure Temperatures Of Ball Bearings

    Science.gov (United States)

    Gibson, John C.; Fredricks, Thomas H.

    1995-01-01

    Rig for testing ball bearings under radial and axial loads and measuring surface temperatures undergoing development. Includes extensible thermocouples: by means of bellows as longitudinal positioners, thermocouples driven into contact with bearing balls to sense temperatures immediately after test run. Not necessary to disassemble rig or to section balls to obtain indirect indications of maximum temperatures reached. Thermocouple measurements indicate temperatures better than temperature-sensitive paints.

  7. Extended Life Testing of Duplex Ball Bearings

    Science.gov (United States)

    Mobley, Jeffrey; Robertson, Michael; Hodges, Charles

    2016-01-01

    Sierra Nevada Corporation’s Space Systems performed bearing life testing for the Scan Mirror Motor/Encoder Assembly (SMMA), part of the Scan Mirror Assembly on-board the Aerosol Polarimetry Sensor (APS) on the NASA Glory Spacecraft. The baseline bearing life test duration extended beyond the launch date for the Glory Spacecraft; a risk that the program was willing to undertake with the understanding that if any anomalies or failures occurred before the required life was achieved, then the mission objectives or operating profile could be modified on orbit to take those results into account. Even though the Glory Spacecraft failed to reach orbit during its launch in March of 2011, the bearing life testing was continued through a mutual understanding of value between Sierra Nevada Corporation and our customer; with a revised goal of testing to failure rather than completing a required number of life cycles. Life testing thus far has not only exceeded the original mission required life, but has also exceeded the published test data for Cumulative Degradation Factor (CDF) from NASA/CR-2009-215681. Many lessons were learned along the way regarding long life testing. The bearing life test has been temporarily suspended due to test support equipment issues.

  8. 3D-printed silicate porous bioceramics using a non-sacrificial preceramic polymer binder.

    Science.gov (United States)

    Zocca, A; Elsayed, H; Bernardo, E; Gomes, C M; Lopez-Heredia, M A; Knabe, C; Colombo, P; Günster, J

    2015-05-22

    Silicate bioceramics possess an excellent bioactivity; however, shaping them into complex geometries is still challenging. Therefore, this paper aims to present a new strategy for the shaping of a bioglass-ceramic with controlled geometry and properties starting from a glass powder combined with a preceramic polymer, i.e. a silicon resin, and reactive fillers. The powder-based three-dimensional (3D)-printing of wollastonite (CaSiO3)-based silicate bioceramic parts was demonstrated in this work. The resin plays a dual role, as it not only acts as a non-sacrificial binder for the filler powders in the printing process but it also reacts with the fillers to generate the desired bioceramic phases. The mechanical and physical properties, i.e. ball-on-three-balls test, density, porosity and morphology, were evaluated in 3D-printed discs. These samples possessed a total porosity around 64 vol% and a biaxial flexural strength around 6 MPa. The raw materials used in this work also enabled the 3D-printing of scaffolds possessing a designed multi-scale porosity, suitable bioceramic phase assemblage and a compressive strength of 1 MPa (for cylindrical scaffolds with total porosity ~80 vol%). Solubility in TRIS/HCl and in vitro assays, i.e. viability, cytotoxicity and apoptosis assays, were also performed. In vitro tests indicated good cell viability and no cytotoxicity effect on the cells.

  9. Extended irreversible thermodynamics and non-equilibrium temperature

    Directory of Open Access Journals (Sweden)

    Casas-Vazquez, Jose'

    2008-02-01

    Full Text Available We briefly review the concept of non-equilibrium temperature from the perspectives of extended irreversible thermodynamics, fluctuation theory, and statistical mechanics. The relations between different proposals are explicitly examined in two especially simple systems: an ideal gas in steady shear flow and a forced harmonic oscillator in a thermal bath. We examine with special detail temperatures related to the average molecular kinetic energy along different spatial directions, to the average configurational energy, to the derivative of the entropy with respect to internal energy, to fluctuation-dissipation relation and discuss their measurement.

  10. Berkeley High-Resolution Ball

    International Nuclear Information System (INIS)

    Diamond, R.M.

    1984-10-01

    Criteria for a high-resolution γ-ray system are discussed. Desirable properties are high resolution, good response function, and moderate solid angle so as to achieve not only double- but triple-coincidences with good statistics. The Berkeley High-Resolution Ball involved the first use of bismuth germanate (BGO) for anti-Compton shield for Ge detectors. The resulting compact shield permitted rather close packing of 21 detectors around a target. In addition, a small central BGO ball gives the total γ-ray energy and multiplicity, as well as the angular pattern of the γ rays. The 21-detector array is nearly complete, and the central ball has been designed, but not yet constructed. First results taken with 9 detector modules are shown for the nucleus 156 Er. The complex decay scheme indicates a transition from collective rotation (prolate shape) to single- particle states (possibly oblate) near spin 30 h, and has other interesting features

  11. Subsurface offset behaviour in velocity analysis with extended reflectivity images

    NARCIS (Netherlands)

    Mulder, W.A.

    2012-01-01

    Migration velocity analysis with the wave equation can be accomplished by focusing of extended migration images, obtained by introducing a subsurface offset or shift. A reflector in the wrong velocity model will show up as a curve in the extended image. In the correct model, it should collapse to a

  12. Texture collapse

    International Nuclear Information System (INIS)

    Prokopec, T.; Sornborger, A.; Brandenberger, R.H.

    1992-01-01

    We study single-texture collapse using a leapfrog discretization method on a 30x30x30 spatial lattice. We investigate the influence of boundary conditions, physical size of the lattice, type of space-time background (flat, i.e., nonexpanding, vs radiation-dominated and matter-dominated universes), and spatial distribution of the initial texture configuration on collapse time and critical winding. For a spherically symmetric initial configuration of size equal to the horizon size on a lattice containing 12 (30) horizon volumes, the critical winding is found to be 0.621±0.001 (0.602±0.003) (flat case), 0.624±0.002 (0.604±0.005) (radiation era), 0.628±0.002 (0.612±0.003) (matter era). The larger the physical size of the lattice (in units of the horizon size), the smaller is the critical winding, and in the limit of an infinite lattice, we argue that the critical winding approaches 0.5. For radially asymmetric cases, contraction of one axis ( /Ipancake case) slightly reduces collapse time and critical winding, and contraction of two axes (d/Icigar case) reduces collapse time and critical winding significantly

  13. Investigation of karst collapse based on 3-D seismic technique and DDA method at Xieqiao coal mine, China

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Jian-Ping; Chen, Zhong-Hui [State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083 (China); Institute of Rock Mechanical and Fractals, China University of Mining and Technology, Beijing 100083 (China); Peng, Su-Ping; Li, Yong-Jun [State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083 (China); Xie, He-Ping [Institute of Rock Mechanical and Fractals, China University of Mining and Technology, Beijing 100083 (China)

    2009-06-01

    Karst collapse is a serious geological problem in most of the coal mines in the north of China, but recently it has been found in the south as well. The present study is aimed at investigating subsidence mechanism and deformation field of a karst collapse column at Xieqiao, in the south of China. A method of three-dimensional (3-D) seismic technique has been successful in exploring the spatial morphology of the karst collapse at Xieqiao, and the discontinuous deformation analysis (DDA) method is used to calculate the deformation field and analyze the subsidence mechanism. The results indicated that DDA could approximately simulate and back analyze the subsidence process and strata deformation fields. The subsidence processes of the collapse column depend on the sizes of the karst caves. With the continuous expansion of the karst caves, a semi-elliptic stress field, local separation strata and fracture zone will be formed around the karst cave. Moreover, they will gradually expand upwards along the vertical direction. The paper also indicates that the subsidence failure stage may trigger a sudden collapse of the karst column because of the sudden energy release. Also, it will make a great impact on the vicinity working face so as to cause a rock burst. The effects of the friction angle of rock strata on the subsidence mechanism were reported firstly based on DDA. (author)

  14. Modeling and Analyzing the Slipping of the Ball Screw

    Directory of Open Access Journals (Sweden)

    Nannan Xu

    Full Text Available AbstractThis paper aims to set up the ball systematic slipping model and analyze the slipping characteristics caused by different factors for a ball screw operating at high speeds. To investigate the ball screw slipping mechanism, transformed coordinate system should be established firstly. Then it is used to set up mathematical modeling for the ball slipping caused by the three main reasons and the speed of slipping can be calculated. Later, the influence of the contact angle, helix angle and screw diameter for ball screw slipping will be analyzed according to the ball slipping model and slipping speeds equation and the slipping analysis will be obtained. Finally, curve of slipping analysis and that of mechanical efficiency of the ball screw analysis by Lin are compared, which will indirectly verify the correctness of the slipping model. The slipping model and the curve of slipping analysis established in this paper will provide theory basis for reducing slipping and improving the mechanical efficiency of a ball screw operating at high speeds.

  15. Mucormycosis (Mucor fungus ball) of the maxillary sinus.

    Science.gov (United States)

    Cho, Hang Sun; Yang, Hoon Shik; Kim, Kyung Soo

    2014-01-01

    A fungus ball is an extramucosal fungal proliferation that completely fills one or more paranasal sinuses and usually occurs as a unilateral infection. It is mainly caused by Aspergillus spp in an immunocompetent host, but some cases of paranasal fungal balls reportedly have been caused by Mucor spp. A Mucor fungus ball is usually found in the maxillary sinus and/or the sphenoid sinus and may be black in color. Patients with mucormycosis, or a Mucor fungal ball infection, usually present with facial pain or headache. On computed tomography, there are no pathognomonic findings that are conclusive for a diagnosis of mucormycosis. In this article we report a case of mucormycosis in a 56-year-old woman and provide a comprehensive review of the literature on the "Mucor fungus ball." To the best of our knowledge, 5 case reports (8 patients) have been published in which the fungus ball was thought to be caused by Mucor spp.

  16. Superspace action for a 6-dimensional non-extended supersymmetric Yang-Mills theory

    International Nuclear Information System (INIS)

    Nilsson, B.E.W.

    1980-01-01

    The ordinary N = 2 extended (abelian) gauge theory is written in the framework of a non-extended theory in 6-dimensional superspace. Graded differential geometry and superfield technique is used to construct a superspace action. The x-space lagrangian arises as the term of second order in theta of the superspace lagrangian. (orig.)

  17. Aerodynamics in the classroom and at the ball park

    Science.gov (United States)

    Cross, Rod

    2012-04-01

    Experiments suitable for classroom projects or demonstrations are described concerning the aerodynamics of polystyrene balls. A light ball with sufficient backspin can curve vertically upward through the air, defying gravity and providing a dramatic visual demonstration of the Magnus effect. A ball projected with backspin can also curve downward with a vertical acceleration greater than that due to gravity if the Magnus force is negative. These effects were investigated by filming the flight of balls projected in an approximately horizontal direction so that the lift and drag forces could be easily measured. The balls were also fitted with artificial raised seams and projected with backspin toward a vertical target in order to measure the sideways deflection over a known horizontal distance. It was found that (a) a ball with a seam on one side can deflect either left or right depending on its launch speed and (b) a ball with a baseball seam can also deflect sideways even when there is no sideways component of the drag or lift forces acting on the ball. Depending on the orientations of the seam and the spin axis, a sideways force on a baseball can arise either if there is rough patch on one side of the ball or if there is a smooth patch. A scuff ball with a rough patch on one side is illegal in baseball. The effect of a smooth patch is a surprising new observation.

  18. Effect of soccer shoe upper on ball behaviour in curve kicks

    Science.gov (United States)

    Ishii, Hideyuki; Sakurai, Yoshihisa; Maruyama, Takeo

    2014-08-01

    New soccer shoes have been developed by considering various concepts related to kicking, such as curving a soccer ball. However, the effects of shoes on ball behaviour remain unclear. In this study, by using a finite element simulation, we investigated the factors that affect ball behaviour immediately after impact in a curve kick. Five experienced male university soccer players performed one curve kick. We developed a finite element model of the foot and ball and evaluated the validity of the model by comparing the finite element results for the ball behaviour immediately after impact with the experimental results. The launch angle, ball velocity, and ball rotation in the finite element analysis were all in general agreement with the experimental results. Using the validated finite element model, we simulated the ball behaviour. The simulation results indicated that the larger the foot velocity immediately before impact, the larger the ball velocity and ball rotation. Furthermore, the Young's modulus of the shoe upper and the coefficient of friction between the shoe upper and the ball had little effect on the launch angle, ball velocity, and ball rotation. The results of this study suggest that the shoe upper does not significantly influence ball behaviour.

  19. Determination of area reduction rate by continuous ball indentation test

    International Nuclear Information System (INIS)

    Zou, Bin; Guan, Kai Shu; Wu, Sheng Bao

    2016-01-01

    Rate of area reduction is an important mechanical property to appraise the plasticity of metals, which is always obtained from the uniaxial tensile test. A methodology is proposed to determine the area reduction rate by continuous ball indentation test technique. The continuum damage accumulation theory has been adopted in this work to identify the failure point in the indentation. The corresponding indentation depth of this point can be obtained and used to estimate the area reduction rate. The local strain limit criterion proposed in the ASME VIII-2 2007 alternative rules is also adopted in this research to convert the multiaxial strain of indentation test to uniaxial strain of tensile test. The pile-up and sink-in phenomenon which can affect the result significantly is also discussed in this paper. This method can be useful in engineering practice to evaluate the material degradation under severe working condition due to the non-destructive nature of ball indentation test. In order to validate the method, continuous ball indentation test is performed on ferritic steel 16MnR and ASTM (A193B16), then the results are compared with that got from the traditional uniaxial tensile test.

  20. Laser Sintering Technology and Balling Phenomenon.

    Science.gov (United States)

    Oyar, Perihan

    2018-02-01

    The aim of this review was to evaluate the balling phenomenon which occurs typically in Selective Laser Sintering (SLS). The balling phenomenon is a typical SLS defect, and observed in laser sintered powder, significantly reduces the quality of SLS, and hinders the further development of SLS Technology. Electronic database searches were performed using Google Scholar. The keywords "laser sintering, selective laser sintering, direct metal laser melting, and balling phenomenon" were searched in title/abstract of publications, limited to December 31, 2016. The inclusion criteria were SLS, balling phenomenon, some alloys (such as Cr-Co, iron, stainless steel, and Cu-based alloys) mechanical properties, microstructure and bond strength between metal-ceramic crown, laboratory studies, full text, and in English language. A total of 100 articles were found the initial search and yielded a total of 50 studies, 30 of which did not fulfill the inclusion criteria and were therefore excluded. In addition, 20 studies were found by screening the reference list of all included publications. Finally, 40 studies were selected for this review. The method in question is regulated by powder material characteristics and the conditions of laser processing. The procedure of formation, affecting factors, and the mechanism of the balling effect are very complex.

  1. Mechanically Induced Graphite-Nanodiamonds-Phase Transformations During High-Energy Ball Milling

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2017-05-01

    Due to their unusual mechanical, chemical, physical, optical, and biological properties, nearly spherical-like nanodiamonds have received much attention as desirable advanced nanomaterials for use in a wide spectrum of applications. Although, nanodiamonds can be successfully synthesized by several approaches, applications of high temperature and/or high pressure may restrict the real applications of such strategic nanomaterials. Distinct from the current preparation approaches used for nanodiamonds preparation, here we show a new process for preparing ultrafine nanodiamonds (3-5 nm) embedded in a homogeneous amorphous-carbon matrix. Our process started from high-energy ball milling of commercial graphite powders at ambient temperature under normal atmospheric helium gas pressure. The results have demonstrated graphite-single wall carbon nanotubes-amorphous-carbon-nanodiamonds phase transformations carried out through three subsequent stages of ball milling. Based on XRD and RAMAN analyses, the percentage of nanodiamond phase + C60 (crystalline phase) produced by ball milling was approximately 81%, while the amorphous phase amount was 19%. The pressure generated on the powder together the with temperature increase upon the ball-powder-ball collision is responsible for the phase transformations occurring in graphite powders.

  2. THE BEHAVIOURAL REACTION OF WEANERS TO HANGING TOYS: WOODEN BALL AND AROMATIZED WOODEN BALL – WAY TO REDUCE AGGRESSION AFTER MIXING

    Directory of Open Access Journals (Sweden)

    Jacek NOWICKI

    2008-05-01

    Full Text Available The behaviour of weaners after mixing housed in pens equipped with hanging wooden ball, aromatized with vanilla fluid hanging wooden ball and without enrichment was evaluated. It was found that both enrichments reduced aggression, however the most interesting for weaners was the aromatized wooden ball.

  3. Kinase inhibition by the Jamaican ball moss, Tillandsia recurvata L.

    Science.gov (United States)

    Lowe, Henry I C; Watson, Charah T; Badal, Simone; Toyang, Ngeh J; Bryant, Joseph

    2012-10-01

    This research was undertaken in order to investigate the inhibitory potential of the Jamaican ball moss, Tillandsia recurvata against several kinases. The inhibition of these kinases has emerged as a potential solution to restoring the tight regulation of normal cellular growth, the loss of which leads to cancer cell formation. Kinase inhibition was investigated using competition binding (to the ATP sites) assays, which have been previously established and authenticated. Four hundred and fifty one kinases were tested against the Jamaican ball moss extract and a dose-response was tested on 40 kinases, which were inhibited by more than 35% compared to the control. Out of the 40 kinases, the Jamaican ball moss selectively inhibited 5 (CSNK2A2, MEK5, GAK, FLT and DRAK1) and obtained Kd(50)s were below 20 μg/ml. Since MEK5 and GAK kinases have been associated with aggressive prostate cancer, the inhibitory properties of the ball moss against them, coupled with its previously found bioactivity towards the PC-3 cell line, makes it promising in the arena of drug discovery towards prostate cancer.

  4. Development of Stick and Ball Sports on Gateball

    Directory of Open Access Journals (Sweden)

    Indriyanti

    2017-10-01

    Full Text Available The purpose of this research is to make product design development of stick and ball sports in gateball. The approach used in this study is a method of Research and Development. The subject of this research is the Central Java on gateball club event gateball in Semarang and Yogyakarta. Experts and expert expert gateball expert in mechanical engineering. The data analysis phase the work field, and the data analysis stage include observation, observation, interviews, and documentation of the test kefektifan products, expert judgment expert expert gateball and expert mechanical engineering expert. The results of this research are stick and ball exercise for beginner players gateball gateball. The result of the validator 3 expert expert from the expert gateball and expert mechanical engineering product validation data beginning the first phase obtained a score above 73 definitions of the criteria of “good”, on the second stage of the product validation data obtained a score above the 81 criteria for “excellent”. The results of the interviews to the development of gateball players 19 stick and ball gateball can not be used to play in a match and can be used for subsequent exercises but for beginners a product development tool model stick and ball gateball “ INC. “can be used to enhance the ability of basic techniques in motion game for players, gateball.

  5. Rolling Friction Torque in Ball-Race Contacts Operating in Mixed Lubrication Conditions

    Directory of Open Access Journals (Sweden)

    Mihaela Rodica D. Bălan

    2015-04-01

    Full Text Available Based on a theoretical model and an experimental methodology for defining the friction torque for lubricated conditions in a modified thrust ball bearing having only three balls, the authors experimentally investigated the influence of the lubricant parameter Λ on friction torque for mixed IVR (isoviscous rigid and EHL (elastohydrodynamic lubrication conditions. The experiments were conducted using ball diameters of 3 mm, 3.97 mm and 6.35 mm loaded at 0.125 N, 0.400 N and 0.633 N. Two oils of viscosity 0.08 Pa·s and 0.05 Pa·s were used and rotational speed was varied in the range 60–210 rpm to obtain a lubricant parameter Λ varying between 0.3 and 3.2. The experiments confirmed that the measured friction torque can be explained using hydrodynamic rolling force relationships respecting the transition from an IVR to an EHL lubrication regime.

  6. Indicators of collapse in systems undergoing unsustainable growth.

    Science.gov (United States)

    Ridolfi, Luca; D'Odorico, Paolo; Laio, Francesco

    2015-02-01

    Unsustainable growth is typical of systems that rely on a finite pool of non-renewable resources that are tapped until they are depleted. The decrease in resource availability eventually leads these systems to a decline. Here we investigate the dynamics of systems that exhibit unsustainable growth and are prone to a collapse to an alternative ("degraded") state. For these systems the possible imminent occurrence of a collapse is difficult to avert because they keep growing as they approach the transition point. It is therefore important to identify some early warning signs that can be used to predict whether the system is approaching a critical and likely irreversible transition to an undesired and degraded state. This study evaluates whether existing theories of precursors of phase transitions based on the critical slowing down phenomenon are applicable as leading indicators of state shift in unsustainable growth dynamics. It is found that such indicators fail to serve as reliable early warning signs of the system's collapse.

  7. Biomechanics of Heading a Soccer Ball: Implications for Player Safety

    Directory of Open Access Journals (Sweden)

    Charles F. Babbs

    2001-01-01

    Full Text Available To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton�s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumably safe daily activities of jumping, dancing, and head nodding and also were related to established criteria for serious head injury from the motor vehicle crash literature. The results suggest heading is usually safe but occasionally dangerous, depending on key characteristics of both the player and the ball. Safety is greatly improved when players head the ball with greater effective body mass, which is determined by a player�s size, strength, and technique. Smaller youth players, because of their lesser body mass, are more at risk of potentially dangerous headers than are adults, even when using current youth size balls. Lower ball inflation pressure reduces risk of dangerous head accelerations. Lower pressure balls also have greater “touch” and “playability”, measured in terms of contact time and contact area between foot and ball during a kick. Focus on teaching proper technique, the re-design of age-appropriate balls for young players with reduced weight and inflation pressure, and avoidance of head contact with fast, rising balls kicked at close range can substantially reduce risk of subtle brain injury in players who head soccer balls.

  8. Rotating collapse of stellar iron cores in general relativity

    International Nuclear Information System (INIS)

    Ott, C D; Dimmelmeier, H; Marek, A; Janka, H-T; Zink, B; Hawke, I; Schnetter, E

    2007-01-01

    We present results from the first 2 + 1 and 3 + 1 simulations of the collapse of rotating stellar iron cores in general relativity employing a finite-temperature equation of state and an approximate treatment of deleptonization during collapse. We compare full 3 + 1 and conformally-flat spacetime evolution methods and find that the conformally-flat treatment is sufficiently accurate for the core-collapse supernova problem. We focus on the gravitational wave (GW) emission from rotating collapse, core bounce and early postbounce phases. Our results indicate that the GW signature of these phases is much more generic than previously estimated. In addition, we track the growth of a nonaxisymmetric instability of dominant m = 1 character in two of our models that leads to prolonged narrow-band GW emission at ∼920-930 Hz over several tens of milliseconds

  9. Hydrodynamical equations for spherical gravitational collapse in terms of a generalized theory of gravitation with higher derivatives

    International Nuclear Information System (INIS)

    Nariai, Hidekazu.

    1986-06-01

    In similar to Misner and Sharp's formalism in general relativity for a spherical gravitational collapse, a formalism for the spherical gravitational collapse is presented on the basis of a generalized theory of gravitation in the sense of Utiyama-DeWitt (which was later extended by Parker's school and Zel'dovich's one). The resulted formalism is somewhat similar to that developed by me in 1972 based on the scalar-tensor theory of gravity. (author)

  10. Infrared Thermographic Diagnosis Mechanism for Fault Detection of Ball Bearing under Dynamic Loading Conditions

    International Nuclear Information System (INIS)

    Seo, Jin Ju; Yoon, Hanvit; Kim, Dong Yeon; Hong, Dong Pyo; Kim, Won Tae

    2011-01-01

    Fault detection for dynamic loading conditions of rotational machineries was considered from the contactless, non-destructive infrared thermographic method, rather than the traditional diagnosis method. In this paper, by applying a rotating deep-grooved ball bearing, passive thermographic experiment was performed as an alternative way proceeding the traditional fault monitoring. In addition, the thermographic experiments were compared with the vibration spectrum analysis to evaluate the efficiency of the proposed method. Based on the results, it was concluded the temperature characteristics of the ball bearing under dynamic loading conditions were analyzed thoroughly

  11. Ear canal collapse prevalence and associated factors among users of a center of prevention and rehabilitation for disabilities

    Directory of Open Access Journals (Sweden)

    Elisana Costa Dourado

    Full Text Available ABSTRACT Purpose: to investigate the prevalence of the ear canal collapse when using supra-aural earphones and to verify if this event is influenced by sex, age, color of the skin and prominent ear. Methods: the collapse was assessed by a visual inspection after the positioning of a detached cushion, pressured against the external ear. Results: a total of 436 individuals, aged 3 to 97 years, participated in the study. Ear canal collapse was observed in 11.4% of the subjects, being mostly bilateral (90.0%. The prevalence ranged from 6.3% to 36.6% across age groups. Males, aged 65 years or above and presence of prominent ear were independently identified as associated factors for the occurrence of ear canal collapse (p<0.05. Despite a higher prevalence for those self-identified as white skinned when compared to non-whites, the difference was not statistically significant. Conclusion: the ear canal collapse, when supra-aural earphones are used, is more likely to occur in men, in elderly people, and among those with prominent ears. The prevalence of the event in this population raises the necessity of a careful examination, previous to any evaluation using supra-aural earphones.

  12. Quasi-stationary gravitational collapse of slowly rotating bodies in general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J C [Oxford Univ. (UK). Dept. of Astrophysics

    1977-05-01

    This paper presents results of quasi-stationary collapse calculations for a class of slowly rotating non-homogeneous bodies in general relativity. The results are qualitatively similar to those obtained previously for homogeneous models indicating that the effects described for the homogeneous models are likely to have some relevance for the gravitational collapse of real stars towards the black hole state. There is also a discussion of some basic questions associated with such calculations.

  13. A general theory for ball lightning structure and light output

    Science.gov (United States)

    Morrow, R.

    2018-03-01

    A general theory for free-floating ball lightning is presented which unifies the phantom plasma ball theory involving the production of very little light, with theories for ball lightning involving light output produced by burning particles from the soil. The mechanism for the formation of plasma balls is shown to be quite general, producing very similar plasma balls independent of initial ion densities over four orders of magnitude. All that is required is an excess of positive ions in the initial ball of ions. The central plasma density after 1 s is shown to be the reciprocal of the ion neutralization coefficient for all cases, both analytically and computationally. Further, the plasma region has zero electric field in all cases. Surrounding the plasma ball is a sphere of positive ions moving away from the centre via their own space-charge field; this space-charge field, which is the same in all cases near the plasma ball, drives negative ions and negative particles towards the plasma centre. The connection with burning particle theories is the proposition that the burning particles are highly-charged which is very likely after a lightning strike. Burning negatively charged particles would be driven into the plasma ball region and trapped while any positively charged particles would be driven away. The plasma ball structure is shown to last more than 10 s and the ‘burnout time’ for a typical coal particle (as an example) has been measured at 5-10 s this is comparable with the lifetimes observed for ball lightning. The light output from a few hundred particles is estimated to be ~1 W, a typical output for ball lightning. Finally, suggestions are made for the generation of ball lightning in the laboratory.

  14. Estimating Wear Of Installed Ball Bearings

    Science.gov (United States)

    Keba, John E.; Mcvey, Scott E.

    1993-01-01

    Simple inspection and measurement technique makes possible to estimate wear of balls in ball bearing, without removing bearing from shaft on which installed. To perform measurement, one observes bearing cage while turning shaft by hand to obtain integral number of cage rotations and to measure, to nearest 2 degrees, number of shaft rotations producing cage rotations. Ratio between numbers of cages and shaft rotations depends only on internal geometry of bearing and applied load. Changes in turns ratio reflect changes in internal geometry of bearing provided measurements made with similar bearing loads. By assuming all wear occurs on balls, one computes effective value for this wear from change in turns ratio.

  15. Algebraic collapsing acceleration of the characteristics method with anisotropic scattering

    International Nuclear Information System (INIS)

    Le Tellier, R.; Hebert, A.; Roy, R.

    2004-01-01

    In this paper, the characteristics solvers implemented in the lattice code Dragon are extended to allow a complete anisotropic treatment of the collision operator. An efficient synthetic acceleration method, called Algebraic Collapsing Acceleration (ACA), is presented. Tests show that this method can substantially speed up the convergence of scattering source iterations. The effect of boundary conditions, either specular or white reflections, on anisotropic scattering lattice-cell problems is also considered. (author)

  16. The f electron collapse revisited

    International Nuclear Information System (INIS)

    Bennett, B.I.

    1987-03-01

    A reexamination of the collapse of 4f and 5f electrons in the lanthanide and actinide series is presented. The calculations show the well-known collapse of the f electron density at the thresholds of these series along with an f 2 collapse between thorium and protactinium. The collapse is sensitive to the choice of model for the exchange-correlation potential and the behavior of the potential at large radius

  17. C, N co-doped TiO_2/TiC_0_._7N_0_._3 composite coatings prepared from TiC_0_._7N_0_._3 powder using ball milling followed by oxidation

    International Nuclear Information System (INIS)

    Hao, Liang; Wang, Zhenwei; Zheng, Yaoqing; Li, Qianqian; Guan, Sujun; Zhao, Qian; Cheng, Lijun; Lu, Yun; Liu, Jizi

    2017-01-01

    Highlights: • TiO_2/TiC_0_._7N_0_._3 coatings were prepared by ball milling followed by oxidation. • In situ co-doping of C and N with simultaneous TiO_2 formation was observed. • Improved photocatalytic activity under UV/visible light was noticed. • Synergism in co-doping and heterojunction formation promoted carrier separation. - Abstract: Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO_2 coatings on the surfaces of Al_2O_3 balls from TiC_0_._7N_0_._3 powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV–vis). The results show that continuous TiC_0_._7N_0_._3 coatings were formed after ball milling. C, N co-doped TiO_2/TiC_0_._7N_0_._3 composite coatings were prepared after the direct oxidization of TiC_0_._7N_0_._3 coatings in the atmosphere. However, TiO_2 was hardly formed in the surface layer of TiC_0_._7N_0_._3 coatings within a depth less than 10 nm during the heat oxidation of TiC_0_._7N_0_._3 coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO_2/TiC_0_._7N_0_._3 composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO_2/TiC_0_._7N_0_._3 composite microstructure.

  18. Ball tip method for thoracic pedicle screw placement in patients with adolescent idiopathic scoliosis

    International Nuclear Information System (INIS)

    Watanabe, Kota; Matsumoto, Morio; Iizuka, Shingo

    2008-01-01

    The purpose of this study was to evaluate the efficacy of ball tip method for thoracic pedicle screw placements in idiopathic scoliosis patients. 24 patients with adolescent idiopathic scoliosis were included in this study. Conventional method was performed in 12 patients. Ball tip method was performed in 12 patients. Accuracy of the pedicle screw placement was evaluated based on the postoperative CT. In the ball tip method, a probe which was consisted of ball tip with flexible shaft was used. After removing of cortical bone at a starting point, the probe was inserted manually or sometimes with gently tapping by hammer. During the maneuver, the probe will gradually progress into cancellous bone in the pedicle, without perforating cortical bone in the pedicle. Following expansion of the hole by a rigid gear shift probe, screw was placed in the pedicle. 65.1% of screws were located within pedicle in the conventional group and 86.5% in the ball tip group. 5.3% of screws were located out of pedicle within 2 mm in the conventional group and 8.2% in the ball tip group. 15.8% of screws were located out of pedicle beyond 2 mm and 1.8% in the ball tip group. The ball tip method enhanced the accuracy of thoracic pedicle screw placements in adolescent idiopathic scoliosis patients. The ball tip method may be effective for accurate pedicle screw placement in patients with adolescent idiopathic scoliosis. (author)

  19. Ball-and-socket ankle joint

    International Nuclear Information System (INIS)

    Pistoia, F.; Ozonoff, M.B.; Wintz, P.; Hartford Hospital, CT

    1987-01-01

    The ball-and-socket ankle joint is a malformation of the ankle in which the articular surface of the talus is hemispherical in both the anteroposterior and lateral projections and has a congruent, concave tibial articular surface. Fourteen patients with this condition were identified retrospectively. Thirteen patients were thought to have the congenital type of ball-and-socket ankle joint which in many was associated with tarsal coalition, short limb, and ray fusion and deletion anomalies. One case of the acquired type, demonstrating less geometric rounding of the talar margins, was seen in a patient with myelomeningocele, probably resulting from sensory and motor deficits. Although the exact etiology of the congenital type is unknown, its association with other malformations suggests that the ball-and-socket ankle joint results from an overall maldevelopment of the ankle and foot. (orig.)

  20. Reduced graphene oxide synthesis by high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, O. [Department of Physics, M.U.C Women' s College, Burdwan 713104 (India); Mitra, S. [MLS Prof' s Unit, Indian Association for the Cultivation of Science, Kolkata 700032 (India); Pal, M. [CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India); Datta, A. [University School of Basic and Applied Science (USBAS), Guru Gobind Singh Indraprastha University, New Delhi 110075 (India); Dhara, S. [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Chakravorty, D., E-mail: mlsdc@iacs.res.in [MLS Prof' s Unit, Indian Association for the Cultivation of Science, Kolkata 700032 (India)

    2015-07-01

    Graphene oxide is transformed to reduced graphene oxide by high energy ball milling in inert atmosphere. The process of ball milling introduces defects and removes oxygen functional groups, thereby creating the possibility of fine tuning the band gap of all intermediate stages of the structural evolution. A limit of the backbone sp{sup 2} network structure has been found which should be able to accommodate defects, before amorphization sets in. The amorphization of graphene oxide is achieved rather quickly in comparison to that of graphite. From thermogravimetric and differential scanning calorimetric analysis along with Fourier transform infrared (FTIR) and Raman spectroscopic studies, it is found that the number of oxygen-containing groups decreases at a faster rate than that of aromatic double bonds with increasing ball milling time with a maximum limit of 3 h. Several characterization techniques (FTIR, Raman, UV–Visible and X-ray photoelectron spectroscopy) have confirmed that the material synthesized is, indeed, reduced graphene oxide. - Highlights: • Graphene oxide is transformed to reduced graphene oxide by high energy ball milling in inert atmosphere. • Fine tuning the band gap by introducing defects and removing oxygen functional groups. • Introduction of excess defects leads to amorphization. • Photoluminescence has been observed in the UV-blue region.

  1. Extending Femtosecond Filamentation of High Power Laser Propagating in the Atmosphere

    Science.gov (United States)

    Eisenmann, Shmuel; Sivan, Yonatan; Fibich, Gadi; Zigler, Arie

    2008-06-01

    We show experimentally for ultrashort laser pulses propagating in air, that the filamentation distance of intense laser pulses in the atmosphere can be extended and controlled with a simple double-lens setup. Using this method we were able to achieve a 20-fold delay of the filamentation distance of non-chirped 120 fs pulses propagating in air, from 16 m to 330 m. At 330 m, the collapsing pulse is sufficiently powerful to create plasma filaments. We also show that the scatter of the filaments at 330 m can be significantly reduced by tilting the second lens. We derive a simple formula for the filamentation distance, and confirm its agreement with the experimental results. We also observe that delaying the onset of filamentation increases the filament length. To the best of our knowledge, this is the longest distance reported in the literature at which plasma filaments were created and controlled. Finally, we show that the peak power at the onset of collapse is significantly higher with the double-lens setup, compared with the standard negative chirping approach.

  2. Three-dimensional simulations of void collapse in energetic materials

    Science.gov (United States)

    Rai, Nirmal Kumar; Udaykumar, H. S.

    2018-03-01

    The collapse of voids in porous energetic materials leads to hot-spot formation and reaction initiation. This work advances the current knowledge of the dynamics of void collapse and hot-spot formation using 3D reactive void collapse simulations in HMX. Four different void shapes, i.e., sphere, cylinder, plate, and ellipsoid, are studied. For all four shapes, collapse generates complex three-dimensional (3D) baroclinic vortical structures. The hot spots are collocated with regions of intense vorticity. The differences in the vortical structures for the different void shapes are shown to significantly impact the relative sensitivity of the voids. Voids of high surface area generate hot spots of greater intensity; intricate, highly contorted vortical structures lead to hot spots of corresponding tortuosity and therefore enhanced growth rates of reaction fronts. In addition, all 3D voids are shown to be more sensitive than their two-dimensional (2D) counterparts. The results provide physical insights into hot-spot formation and growth and point to the limitations of 2D analyses of hot-spot formation.

  3. Collapsed state of polyglutamic acid results in amyloid spherulite formation.

    Science.gov (United States)

    Stehli, Daniel; Mulaj, Mentor; Miti, Tatiana; Traina, Joshua; Foley, Joseph; Muschol, Martin

    2015-01-01

    Self-assembly of proteins and peptides into amyloid fibrils involves multiple distinct intermediates and late-stage fibrillar polymorphs. Understanding the conditions and mechanisms that promote the formation of one type of intermediate and polymorph over the other represents a fundamental challenge. Answers to this question are also of immediate biomedical relevance since different amyloid aggregate species have been shown to have distinct pathogenic potencies. One amyloid polymorph that has received comparatively little attention are amyloid spherulites. Here we report that self-assembly of the intrinsically disordered polymer poly(L-glutamic) acid (PLE) can generate amyloid spherulites. We characterize spherulite growth kinetics, as well as the morphological, optical and tinctorial features of this amyloid polymorph previously unreported for PLE. We find that PLE spherulites share both tinctorial and structural characteristics with their amyloid fibril counterparts. Differences in PLE's molecular weight, polydispersity or chemistry could not explain the selective propensity toward either fibril or spherulite formation. Instead, we provide evidence that PLE polymers can exist in either a collapsed globule or an extended random coil conformation. The collapsed globule consistently produces spherulites while the extended coil assembles into disordered fibril bundles. This results suggests that these 2 PLE conformers directly affect the morphology of the resulting macroscopic amyloid assembly.

  4. Collapsed state of polyglutamic acid results in amyloid spherulite formation

    Science.gov (United States)

    Stehli, Daniel; Mulaj, Mentor; Miti, Tatiana; Traina, Joshua; Foley, Joseph; Muschol, Martin

    2015-01-01

    Self-assembly of proteins and peptides into amyloid fibrils involves multiple distinct intermediates and late-stage fibrillar polymorphs. Understanding the conditions and mechanisms that promote the formation of one type of intermediate and polymorph over the other represents a fundamental challenge. Answers to this question are also of immediate biomedical relevance since different amyloid aggregate species have been shown to have distinct pathogenic potencies. One amyloid polymorph that has received comparatively little attention are amyloid spherulites. Here we report that self-assembly of the intrinsically disordered polymer poly(L-glutamic) acid (PLE) can generate amyloid spherulites. We characterize spherulite growth kinetics, as well as the morphological, optical and tinctorial features of this amyloid polymorph previously unreported for PLE. We find that PLE spherulites share both tinctorial and structural characteristics with their amyloid fibril counterparts. Differences in PLE's molecular weight, polydispersity or chemistry could not explain the selective propensity toward either fibril or spherulite formation. Instead, we provide evidence that PLE polymers can exist in either a collapsed globule or an extended random coil conformation. The collapsed globule consistently produces spherulites while the extended coil assembles into disordered fibril bundles. This results suggests that these 2 PLE conformers directly affect the morphology of the resulting macroscopic amyloid assembly. PMID:28232889

  5. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al2O3 Nanocomposite Synthesized by Ball Milling and Powder Metallurgy

    Science.gov (United States)

    Matori, Khamirul Amin; Ostovan, Farhad; Abdul Aziz, Sidek; Mamat, Md Shuhazlly

    2017-01-01

    The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3) has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV), nano-hardness (HN), and Young’s modulus (E) of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively. PMID:29072632

  6. Effect of Milling Time on the Microstructure, Physical and Mechanical Properties of Al-Al2O3 Nanocomposite Synthesized by Ball Milling and Powder Metallurgy

    Directory of Open Access Journals (Sweden)

    Meysam Toozandehjani

    2017-10-01

    Full Text Available The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3 has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV, nano-hardness (HN, and Young’s modulus (E of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.

  7. Collapse above the world's largest potash mine (Ural, Russia.

    Directory of Open Access Journals (Sweden)

    Andrejchuk Vjacheslav

    2002-01-01

    Full Text Available This paper reports the results of the study of a huge collapse that occurred in June 1986 within the area of the 3rd Berezniki potash mine (the Verkhnekamsky potash deposit, Ural. Processes that took place between the first appearance of a water inflow through the mine roof and the eventual collapse are reconstructed in detail. The origin and development of a cavity that induced the collapse are revealed. Two factors played a major role in the formation of the collapse: the presence of a tectonic fold/rupture zone with in both the salt sequence and the overburden (the zone of crush and enhanced permeability, and the ductile pillars mining system.

  8. Geotechnical properties of Egyptian collapsible soils

    Directory of Open Access Journals (Sweden)

    Khaled E. Gaaver

    2012-09-01

    Full Text Available The risk of constructing structures on collapsible soils presents significant challenges to geotechnical engineers due to sudden reduction in volume upon wetting. Identifying collapsible soils when encountered in the field and taking the needed precautions should substantially reduce the risk of such problems usually reported in buildings and highways. Collapsible soils are those unsaturated soils that can withstand relatively high pressure without showing significant change in volume, however upon wetting; they are susceptible to a large and sudden reduction in volume. Collapsible soils cover significant areas around the world. In Egypt, collapsible soils were observed within the northern portion of the western desert including Borg El-Arab region, and around the city of Cairo in Six-of-October plateau, and Tenth-of-Ramadan city. Settlements associated with development on untreated collapsible soils usually lead to expensive repairs. One method for treating collapsible soils is to densify their structure by compaction. The ongoing study presents the effect of compaction on the geotechnical properties of the collapsible soils. Undisturbed block samples were recovered from test pits at four sites in Borg El-Arab district, located at about 20 km west of the city of Alexandria, Egypt. The samples were tested in both unsoaked and soaked conditions. Influence of water inundation on the geotechnical properties of collapsible soils was demonstrated. A comparative study between natural undisturbed and compacted samples of collapsible soils was performed. An attempt was made to relate the collapse potential to the initial moisture content. An empirical correlation between California Bearing Ratio of the compacted collapsible soils and liquid limit was adopted. The presented simple relationships should enable the geotechnical engineers to estimate the complex parameters of collapsible soils using simple laboratory tests with a reasonable accuracy.

  9. Gap junctions are selectively associated with interlocking ball-and-sockets but not protrusions in the lens.

    Science.gov (United States)

    Biswas, Sondip K; Lee, Jai Eun; Brako, Lawrence; Jiang, Jean X; Lo, Woo-Kuen

    2010-11-09

    Ball-and-sockets and protrusions are specialized interlocking membrane domains between lens fibers of all species studied. Ball-and-sockets and protrusions are similar in their shape, size, and surface morphology, and are traditionally believed to play a key role in maintaining fiber-to-fiber stability. Here, we evaluate the hypothesis that ball-and-sockets and protrusions possess important structural and functional differences during fiber cell differentiation and maturation. Intact lenses of leghorn chickens (E7 days to P62 weeks old) and rhesus monkeys (1.5-20 years old) were studied with SEM, freeze-fracture TEM, freeze-fracture immunogold labeling (FRIL), and filipin cytochemistry for membrane cholesterol detection. SEM showed that ball-and-sockets were distributed along the long and short sides of hexagonal fiber cells, whereas protrusions were located along the cell corners, from superficial to deep cortical regions in both chicken and monkey lenses. Importantly, by freeze-fracture TEM, we discovered the selective association of gap junctions with all ball-and-sockets examined, but not with protrusions, in both species. In the embryonic chicken lens (E18), the abundant distribution of ball-and-socket gap junctions was regularly found in an approximate zone extending at least 300 μm deep from the equatorial surface of the superficial cortical fibers. Many ball-and-socket gap junctions often protruded deeply into neighboring cells. However, in the mature fibers of monkey lenses, several ball-and-sockets exhibited only partial occupancy of gap junctions with disorganized connexons, possibly due to degradation of gap junctions during fiber maturation and aging. FRIL analysis confirmed that both connexin46 (Cx46) and connexin50 (Cx50) antibodies specifically labeled ball-and-socket gap junctions, but not protrusions. Furthermore, filipin cytochemistry revealed that the ball-and-socket gap junctions contained different amounts of cholesterol (i.e., cholesterol

  10. A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor.

    Science.gov (United States)

    Zhang, Huayu; Xie, Fengqin; Cao, Maoyong; Zhong, Mingming

    2017-07-01

    To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.

  11. Radar speed gun true velocity measurements of sports-balls in flight: application to tennis

    International Nuclear Information System (INIS)

    Robinson, Garry; Robinson, Ian

    2016-01-01

    Spectators of ball-games often seem to be fascinated by the speed of delivery of the ball. They appear to be less interested in or even oblivious to the mechanism and accuracy of the measurement or where in the flight path of the ball the measurement is actually made. Radar speed guns using the Doppler effect are often employed for such speed measurements. It is well known that such guns virtually always measure the line-of-sight or radial velocity of the ball and as such will return a reading less than or equal to the true speed of the ball. In this paper, using only basic physics principles we investigate such measurements, in particular those associated with the service stroke in tennis. For the service trajectories employed here, a single radar gun located in line with the centre-line of the court in fact under-estimates the speed of a wide serve by about 3.4% at the point of delivery, and by about 14.3% on impact with the court. However, we demonstrate that both the magnitude and direction of the true velocity of the ball throughout its entire flight path may be obtained, at least in principle, by the use of four suitably placed radar speed guns. These four guns must be able to measure the ‘range’ to the ball, enabling its position in flight to be determined, and three of them must be able to measure the radial velocity of the ball. Restrictions on the locations of the speed guns are discussed. Such restrictions are quite liberal, although there are certain configurations of the radar gun positions which cannot be used. Importantly, with the one proviso that no speed gun can be directly in the path of the ball (not only for the obvious reasons), we find that if the speed of the ball can be determined for one point in the trajectory, it can also be determined for all points. The accuracy of the range and radial velocity measurements required to give meaningful results for the true velocity are also briefly discussed. It is found that the accuracy required

  12. CVD carbon powders modified by ball milling

    Directory of Open Access Journals (Sweden)

    Kazmierczak Tomasz

    2015-09-01

    Full Text Available Carbon powders produced using a plasma assisted chemical vapor deposition (CVD methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

  13. New topological invariants for non-abelian antisymmetric tensor fields from extended BRS algebra

    International Nuclear Information System (INIS)

    Boukraa, S.; Maillet, J.M.; Nijhoff, F.

    1988-09-01

    Extended non-linear BRS and Gauge transformations containing Lie algebra cocycles, and acting on non-abelian antisymmetric tensor fields are constructed in the context of free differential algebras. New topological invariants are given in this framework. 6 refs

  14. Mechanisms of cascade collapse

    International Nuclear Information System (INIS)

    Diaz de la Rubia, T.; Smalinskas, K.; Averback, R.S.; Robertson, I.M.; Hseih, H.; Benedek, R.

    1988-12-01

    The spontaneous collapse of energetic displacement cascades in metals into vacancy dislocation loops has been investigated by molecular dynamics (MD) computer simulation and transmission electron microscopy (TEM). Simulations of 5 keV recoil events in Cu and Ni provide the following scenario of cascade collapse: atoms are ejected from the central region of the cascade by replacement collision sequences; the central region subsequently melts; vacancies are driven to the center of the cascade during resolidification where they may collapse into loops. Whether or not collapse occurs depends critically on the melting temperature of the metal and the energy density and total energy in the cascade. Results of TEM are presented in support of this mechanism. 14 refs., 4 figs., 1 tab

  15. Induced Matter Theory of gravity from a Weitzenboeck 5D vacuum and pre-big bang collapse of the universe

    International Nuclear Information System (INIS)

    Romero, Jesus Martin; Bellini, Mauricio

    2013-01-01

    We extend the Induced Matter Theory of gravity (IMT) to 5D curved spacetimes by using the Weitzenboeck representation of connections on a 5D curved spacetime. In this representation the 5D curvature tensor becomes null, so that we can make a static foliation on the extra non-compact coordinate to induce in the Weitzenboeck representation the Einstein equations. Once we have done it, we can rewrite the effective 4D Einstein equations in the Levi-Civita representation. This generalization of IMT opens a huge window of possible applications for this theory. A pre-big bang collapsing scenario is explored as an example. (orig.)

  16. Induced Matter Theory of gravity from a Weitzenboeck 5D vacuum and pre-big bang collapse of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Jesus Martin [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Mar del Plata (Argentina); Bellini, Mauricio [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Mar del Plata (Argentina); Universidad Nacional de Mar del Plata, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Funes 3350, C.P. 7600, Mar del Plata (Argentina)

    2013-02-15

    We extend the Induced Matter Theory of gravity (IMT) to 5D curved spacetimes by using the Weitzenboeck representation of connections on a 5D curved spacetime. In this representation the 5D curvature tensor becomes null, so that we can make a static foliation on the extra non-compact coordinate to induce in the Weitzenboeck representation the Einstein equations. Once we have done it, we can rewrite the effective 4D Einstein equations in the Levi-Civita representation. This generalization of IMT opens a huge window of possible applications for this theory. A pre-big bang collapsing scenario is explored as an example. (orig.)

  17. The evolution of the temperature field during cavity collapse in liquid nitromethane. Part II: reactive case

    Science.gov (United States)

    Michael, L.; Nikiforakis, N.

    2018-02-01

    This work is concerned with the effect of cavity collapse in non-ideal explosives as a means of controlling their sensitivity. The main objective is to understand the origin of localised temperature peaks (hot spots) which play a leading order role at the early stages of ignition. To this end, we perform two- and three-dimensional numerical simulations of shock-induced single gas-cavity collapse in liquid nitromethane. Ignition is the result of a complex interplay between fluid dynamics and exothermic chemical reaction. In the first part of this work, we focused on the hydrodynamic effects in the collapse process by switching off the reaction terms in the mathematical formulation. In this part, we reinstate the reactive terms and study the collapse of the cavity in the presence of chemical reactions. By using a multi-phase formulation which overcomes current challenges of cavity collapse modelling in reactive media, we account for the large density difference across the material interface without generating spurious temperature peaks, thus allowing the use of a temperature-based reaction rate law. The mathematical and physical models are validated against experimental and analytic data. In Part I, we demonstrated that, compared to experiments, the generated hot spots have a more complex topological structure and that additional hot spots arise in regions away from the cavity centreline. Here, we extend this by identifying which of the previously determined high-temperature regions in fact lead to ignition and comment on the reactive strength and reaction growth rate in the distinct hot spots. We demonstrate and quantify the sensitisation of nitromethane by the collapse of the isolated cavity by comparing the ignition times of nitromethane due to cavity collapse and the ignition time of the neat material. The ignition in both the centreline hot spots and the hot spots generated by Mach stems occurs in less than half the ignition time of the neat material. We compare

  18. Training simulator for teaching a technique to the long transmission of ball in basket-ball by a method by an arcuated hand from above with threaten

    Directory of Open Access Journals (Sweden)

    Charikova K.M.

    2012-03-01

    Full Text Available Technical devices which used in basket-ball are considered. The features of constructing of trainers and method of their application are selected in a training process. A trainer is offered for teaching a technique to the long transmission of ball in basket-ball. A trainer is a moving on a rope imitator of basket-ball ball. This construction allows to design initial position, замах for implementation of transmission and line of acceleration of ball in the final phase of motion. The method of the use of trainer is developed in an educational process.

  19. The Final Stage of Gravitationally Collapsed Thick Matter Layers

    Directory of Open Access Journals (Sweden)

    Piero Nicolini

    2013-01-01

    Full Text Available In the presence of a minimal length, physical objects cannot collapse to an infinite density, singular, matter point. In this paper, we consider the possible final stage of the gravitational collapse of “thick” matter layers. The energy momentum tensor we choose to model these shell-like objects is a proper modification of the source for “noncommutative geometry inspired,” regular black holes. By using higher momenta of Gaussian distribution to localize matter at finite distance from the origin, we obtain new solutions of the Einstein equation which smoothly interpolates between Minkowski’s geometry near the center of the shell and Schwarzschild’s spacetime far away from the matter layer. The metric is curvature singularity free. Black hole type solutions exist only for “heavy” shells; that is, M ≥Me, where Me is the mass of the extremal configuration. We determine the Hawking temperature and a modified area law taking into account the extended nature of the source.

  20. Magnetic properties of ball-milled Fe0.6Mn0.1Al0.3 alloys

    International Nuclear Information System (INIS)

    Rebolledo, A.F.; Romero, J.J.; Cuadrado, R.; Gonzalez, J.M.; Pigazo, F.; Palomares, F.J.; Medina, M.H.; Perez Alcazar, G.A.

    2007-01-01

    The FeMnAl-disordered alloy system exhibits, depending on the composition and the temperature, a rich variety of magnetic phases including the occurrence of ferromagnetism, antiferromagnetism, paramagnetism and spin-glass and reentrant spin glass behaviors. These latter phases result from the presence of atomic disorder and magnetic dilution and from the competing exchange interactions taking place between an Fe atom and its Mn and Fe first neighbors. The use of mechanical alloying in order to prepare these alloys is specially interesting since it allows to introduce in a progressive way large amounts of disorder. In this work, we describe the evolution with the milling time of the temperature dependence of the magnetic properties of mechanically alloyed Fe 0.6 Mn 0.1 Al 0.3 samples. The materials were prepared in a planetary ball mill using a balls-to-powder mass ratio of 15:1 and pure (99.95 at%) Fe, Mn and Al powders for times up to 19 h. The X-rays diffraction (XRD) spectra show the coexistence of three phases at short milling times. For milling times over 6 h, only the FeMnAl ternary alloy BCC phase is observed. Moesbauer spectroscopy reveals the complete formation of the FeMnAl alloy after 9 h milling time. The magnetic characterization showed that all the samples were ferromagnetic at room temperature with coercivities decreasing from 105 Oe (3 h milled sample) down to 5 Oe in the case of the sample milled for 19 h

  1. Non-linear realization of α0 -extended supersymmetry

    International Nuclear Information System (INIS)

    Nishino, Hitoshi

    2000-01-01

    As generalizations of the original Volkov-Akulov action in four-dimensions, actions are found for all space-time dimensions D invariant under N non-linear realized global supersymmetries. We also give other such actions invariant under the global non-linear supersymmetry. As an interesting consequence, we find a non-linear supersymmetric Born-Infeld action for a non-Abelian gauge group for arbitrary D and N , which coincides with the linearly supersymmetric Born-Infeld action in D=10 at the lowest order. For the gauge group U(N) for M(atrix)-theory, this model has N 2 -extended non-linear supersymmetries, so that its large N limit corresponds to the infinitely many (α 0 ) supersymmetries. We also perform a duality transformation from F μν into its Hodge dual N μ 1 ctdot μD-2 . We next point out that any Chern-Simons action for any (super)groups has the non-linear supersymmetry as a hidden symmetry. Subsequently, we present a superspace formulation for the component results. We further find that as long as superspace supergravity is consistent, this generalized Volkov-Akulov action can further accommodate such curved superspace backgrounds with local supersymmetry, as a super p -brane action with fermionic kappa-symmetry. We further elaborate these results to what we call 'simplified' (Supersymmetry) 2 -models, with both linear and non-linear representations of supersymmetries in superspace at the same time. Our result gives a proof that there is no restriction on D or N for global non-linear supersymmetry. We also see that the non-linear realization of supersymmetry in 'curved' space-time can be interpreted as 'non-perturbative' effect starting with the 'flat' space-time

  2. On the role of the magnetic tension during the gravitational collapse of a magnetised fluid

    International Nuclear Information System (INIS)

    Tsagas, Christos G

    2005-01-01

    We investigate the physics of magnetised gravitational collapse by studying the behaviour of a timelike congruence of non-geodesic worldlines in the presence of a magnetic field. We show that the general relativistic coupling between magnetism and geometry, and the tension properties of the field, lead to magneto-curvature stresses that resist the collapse. When these tension stresses dominate, they can prevent an initially converging family of non-geodesic worldlines from focusing without violating the standard energy conditions

  3. Ball lightning as a route to fusion energy

    International Nuclear Information System (INIS)

    Roth, J.R.

    1989-01-01

    The reality of ball lightning is attested to by observations reported in surveys of large populations, which are the subject of several books. These observations indicate that its characteristics may be relevant to fusion energy applications. Ball lightning can have a diameter up to several meters, a lifetime of over 100 seconds, an energy content in excess of 10 megajoules, and an energy density and a kinetic pressure greater than that of a reacting DT plasma. This paper reviews some of the properties of ball lightning which commend it to the attention of the fusion community, and it discusses some potential advantages and applications of ball lightning fusion reactors. 11 refs., 6 figs., 1 tab

  4. Endograft Collapse After Endovascular Treatment for Thoracic Aortic Disease

    International Nuclear Information System (INIS)

    Bandorski, Dirk; Brueck, Martin; Guenther, Hans-Ulrich; Manke, Christoph

    2010-01-01

    Endovascular treatment is an established therapy for thoracic aortic disease. Collapse of the endograft is a potentially fatal complication. We reviewed 16 patients with a thoracic endograft between 2001 and 2006. Medical records of the treated patients were studied. Data collected include age, gender, diagnosis, indication for endoluminal treatment, type of endograft, and time of follow up. All patients (n = 16; mean age, 61 years; range, 21-82 years) underwent computed tomography (CT) for location of the lesion and planning of the intervention. Time of follow-up with CT scan ranged from 1 to 61 months. Indications for endovascular treatment were degenerative aneurysm (n = 7; 44%), aortic dissection (n = 2; 12%), perforated aortic ulcer (n = 4; 25%), and traumatic aortic injury (n = 3; 19%). Three patients suffered from a collapse of the endograft (one patient distal, two patients proximal) between 3 and 8 days after endovascular treatment. These patients were younger (mean age, 37 ± 25 years vs. 67 ± 16 years; P 0.05]; distal, 45 ± 23.5% vs. 38 ± 21.7% [P > 0.05]). Proximal collapse was corrected by placing a bare stent. In conclusion, risk factors for stent-graft collapse are a small lumen of the aorta and a small radius of the aortic arch curvature (young patients), as well as oversizing, which is an important risk factor and is described for different types of endografts and protheses (Gore TAG and Cook Zenith). Dilatation of the collapsed stent-graft is not sufficient. Following therapy implantation of a second stent or surgery is necessary in patients with a proximal endograft collapse. Distal endograft collapse can possibly be treated conservatively under close follow-up.

  5. Fast-ball sports experts depend on an inhibitory strategy to reprogram their movement timing.

    Science.gov (United States)

    Nakamoto, Hiroki; Ikudome, Sachi; Yotani, Kengo; Maruyama, Atsuo; Mori, Shiro

    2013-07-01

    The purpose of our study was to clarify whether an inhibitory strategy is used for reprogramming of movement timing by experts in fast-ball sports when they correct their movement timing due to unexpected environmental changes. We evaluated the influence of disruption of inhibitory function of the right inferior frontal gyrus (rIFG) on reprogramming of movement timing of experts and non-experts in fast-ball sports. The task was to manually press a button to coincide with the arrival of a moving target. The target moved at a constant velocity, and its velocity was suddenly either increased or decreased in some trials. The task was performed either with or without transcranial magnetic stimulation (TMS), which was delivered to the region of the rIFG. Under velocity change conditions without TMS, the experts showed significantly smaller timing errors and a higher rate of reprogramming of movement timing than the non-experts. Moreover, TMS application during the task significantly diminished the expert group's performance, but not the control group, particularly in the condition where the target velocity decreases. These results suggest that experts use an inhibitory strategy for reprogramming of movement timing. In addition, the rIFG inhibitory function contributes to the superior movement correction of experts in fast-ball sports.

  6. Tunneling into microstate geometries: quantum effects stop gravitational collapse

    International Nuclear Information System (INIS)

    Bena, Iosif; Mayerson, Daniel R.; Puhm, Andrea; Vercnocke, Bert

    2016-01-01

    Collapsing shells form horizons, and when the curvature is small classical general relativity is believed to describe this process arbitrarily well. On the other hand, quantum information theory based (fuzzball/firewall) arguments suggest the existence of some structure at the black hole horizon. This structure can only form if classical general relativity stops being the correct description of the collapsing shell before it reaches the horizon size. We present strong evidence that classical general relativity can indeed break down prematurely, by explicitly computing the quantum tunneling amplitude of a collapsing shell of branes into smooth horizonless microstate geometries. We show that the amplitude for tunneling into microstate geometries with a large number of topologically non-trivial cycles is parametrically larger than e −S BH , which indicates that the shell can tunnel into a horizonless configuration long before the horizon has any chance to form. We also use this technology to investigate the tunneling of M2 branes into LLM bubbling geometries.

  7. Effect of panel shape of soccer ball on its flight characteristics

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2014-05-01

    Soccer balls are typically constructed from 32 pentagonal and hexagonal panels. Recently, however, newer balls named Cafusa, Teamgeist 2, and Jabulani were respectively produced from 32, 14, and 8 panels with shapes and designs dramatically different from those of conventional balls. The newest type of ball, named Brazuca, was produced from six panels and will be used in the 2014 FIFA World Cup in Brazil. There have, however, been few studies on the aerodynamic properties of balls constructed from different numbers and shapes of panels. Hence, we used wind tunnel tests and a kick-robot to examine the relationship between the panel shape and orientation of modern soccer balls and their aerodynamic and flight characteristics. We observed a correlation between the wind tunnel test results and the actual ball trajectories, and also clarified how the panel characteristics affected the flight of the ball, which enabled prediction of the trajectory.

  8. An early record of ball lightning: Oliva (Spain), 1619

    Science.gov (United States)

    Domínguez-Castro, Fernando

    2018-05-01

    In a primary documentary source we found an early record of ball lightning (BL), which was observed in the monastery of Pi (Oliva, southeastern Spain) on 18 October 1619. The ball lightning was observed by at least three people and was described as a rolling burning vessel and a ball of fire. The ball lightning appeared following a lightning flash, showed a mainly horizontal motion, crossed a wall, smudged an image of the Lady of Rebollet (then known as Lady of Pi) and burnt her ruff, and overturned a cross.

  9. Collapse and bounce of null fluids

    OpenAIRE

    Creelman, Bradley; Booth, Ivan

    2016-01-01

    Exact solutions describing the spherical collapse of null fluids can contain regions which violate the energy conditions. Physically the violations occur when the infalling matter continues to move inwards even when non-gravitational repulsive forces become stronger than gravity. In 1991 Ori proposed a resolution for these violations: spacetime surgery should be used to replace the energy condition violating region with an outgoing solution. The matter bounces. We revisit and implement this p...

  10. Collapse and dispersal of a homogeneous spin fluid in Einstein-Cartan theory

    Science.gov (United States)

    Hashemi, M.; Jalalzadeh, S.; Ziaie, A. H.

    2015-02-01

    In the present work, we revisit the process of gravitational collapse of a spherically symmetric homogeneous dust fluid which is described by the Oppenheimer-Snyder (OS) model (Oppenheimer and Snyder in Phys Rev D 56:455, 1939). We show that such a scenario would not end in a spacetime singularity when the spin degrees of freedom of fermionic particles within the collapsing cloud are taken into account. To this purpose, we take the matter content of the stellar object as a homogeneous Weyssenhoff fluid. Employing the homogeneous and isotropic FLRW metric for the interior spacetime setup, it is shown that the spin of matter, in the context of a negative pressure, acts against the pull of gravity and decelerates the dynamical evolution of the collapse in its later stages. Our results show a picture of gravitational collapse in which the collapse process halts at a finite radius, whose value depends on the initial configuration. We thus show that the spacetime singularity that occurs in the OS model is replaced by a non-singular bounce beyond which the collapsing cloud re-expands to infinity. Depending on the model parameters, one can find a minimum value for the boundary of the collapsing cloud or correspondingly a threshold value for the mass content below which the horizon formation can be avoided. Our results are supported by a thorough numerical analysis.

  11. Collapse and dispersal of a homogeneous spin fluid in Einstein-Cartan theory

    International Nuclear Information System (INIS)

    Hashemi, M.; Jalalzadeh, S.; Ziaie, A.H.

    2015-01-01

    In the present work, we revisit the process of gravitational collapse of a spherically symmetric homogeneous dust fluid which is described by the Oppenheimer-Snyder (OS) model (Oppenheimer and Snyder in Phys Rev D 56:455, 1939). We show that such a scenario would not end in a spacetime singularity when the spin degrees of freedom of fermionic particles within the collapsing cloud are taken into account. To this purpose, we take the matter content of the stellar object as a homogeneous Weyssenhoff fluid. Employing the homogeneous and isotropic FLRW metric for the interior spacetime setup, it is shown that the spin of matter, in the context of a negative pressure, acts against the pull of gravity and decelerates the dynamical evolution of the collapse in its later stages. Our results show a picture of gravitational collapse in which the collapse process halts at a finite radius, whose value depends on the initial configuration. We thus show that the spacetime singularity that occurs in the OS model is replaced by a non-singular bounce beyond which the collapsing cloud re-expands to infinity. Depending on the model parameters, one can find a minimum value for the boundary of the collapsing cloud or correspondingly a threshold value for the mass content below which the horizon formation can be avoided. Our results are supported by a thorough numerical analysis. (orig.)

  12. A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor

    Directory of Open Access Journals (Sweden)

    Huayu Zhang

    2017-07-01

    Full Text Available To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor, magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.

  13. Tracking of ball and players in beach volleyball videos.

    Directory of Open Access Journals (Sweden)

    Gabriel Gomez

    Full Text Available This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points.

  14. Tracking of Ball and Players in Beach Volleyball Videos

    Science.gov (United States)

    Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

    2014-01-01

    This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. PMID:25426936

  15. Supersymmetric dark-matter Q-balls and their interactions in matter

    International Nuclear Information System (INIS)

    Kusenko, Alexander; Loveridge, Lee C.; Shaposhnikov, Mikhail

    2005-01-01

    Supersymmetric extensions of the Standard Model contain nontopological solitons, Q-balls, which can be stable and can be a form of cosmological dark matter. Understanding the interaction of SUSY Q-balls with matter fermions is important for both astrophysical limits and laboratory searches for these dark-matter candidates. We show that a baryon scattering off a baryonic SUSY Q-ball can convert into its antiparticle with a high probability, while the baryon number of the Q-ball is increased by two units. For a SUSY Q-ball interacting with matter, this process dominates over those previously discussed in the literature

  16. Spherical dust collapse in higher dimensions

    International Nuclear Information System (INIS)

    Goswami, Rituparno; Joshi, Pankaj S.

    2004-01-01

    We consider here whether it is possible to recover cosmic censorship when a transition is made to higher-dimensional spacetimes, by studying the spherically symmetric dust collapse in an arbitrary higher spacetime dimension. It is pointed out that if only black holes are to result as the end state of a continual gravitational collapse, several conditions must be imposed on the collapsing configuration, some of which may appear to be restrictive, and we need to study carefully if these can be suitably motivated physically in a realistic collapse scenario. It would appear, that, in a generic higher-dimensional dust collapse, both black holes and naked singularities would develop as end states as indicated by the results here. The mathematical approach developed here generalizes and unifies the earlier available results on higher-dimensional dust collapse as we point out. Further, the dependence of black hole or naked singularity end states as collapse outcomes on the nature of the initial data from which the collapse develops is brought out explicitly and in a transparent manner as we show here. Our method also allows us to consider here in some detail the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse

  17. Spherically symmetric radiation in gravitational collapse

    International Nuclear Information System (INIS)

    Bridy, D.J.

    1983-01-01

    This paper investigates a previously neglected mode by which a star may lose energy in the late stages of gravitational collapse to the black hole state. A model consisting of a Schwarzschild exterior matched to a Friedman interior of collapsing pressureless dust is studied. The matter of the collapsing star is taken as the source of a massive vector boson field and a detailed boundary value problem is carried out. Vector mesons are strongly coupled to all nucleons and will be radiated by ordinary matter during the collapse. The time dependent coupling between interior and exterior modes matched across the moving boundary of the collapsing star and the presence of the gravitational fields and their gradients in the field equations may give rise to a parametric amplification mechanism and permit the gravitational field to pump energy into the boson field, greatly enhancing the amount of boson radiation. The significance of a radiative mechanism driven by collapse is that it can react back upon the collapsing source and deprive it of some of the very mass that drives the collapse via its self gravitation. If the mass loss is great enough, this may provide a mechanism to slow or even halt gravitational collapse in some cases

  18. Spherical Collapse in Chameleon Models

    CERN Document Server

    Brax, Ph; Steer, D A

    2010-01-01

    We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse depends on the initial comoving size of the inhomogeneity.

  19. Spherical collapse in chameleon models

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Ph. [Institut de Physique Théorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Rosenfeld, R. [Instituto de Física Teórica, Universidade Estadual Paulista, Rua Dr. Bento T. Ferraz, 271, 01140-070, São Paulo (Brazil); Steer, D.A., E-mail: brax@spht.saclay.cea.fr, E-mail: rosenfel@ift.unesp.br, E-mail: daniele.steer@apc.univ-paris7.fr [APC, UMR 7164, CNRS, Université Paris 7, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France)

    2010-08-01

    We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse in principle depends on the initial comoving size of the inhomogeneity.

  20. Spherical collapse in chameleon models

    International Nuclear Information System (INIS)

    Brax, Ph.; Rosenfeld, R.; Steer, D.A.

    2010-01-01

    We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse in principle depends on the initial comoving size of the inhomogeneity

  1. Pilot study of ice-ball cryotherapy for radiation-induced oral mucositis

    International Nuclear Information System (INIS)

    Ohyama, Waichiro; Ebihara, Satoshi

    1996-01-01

    Oral mucositis caused by radiotherapy is intractable and may worsen the patient's nutritional condition and interrupt treatment. To reduce the incidence and severity of oral mucositis induced by cancer therapy and promote early improvement of its symptoms, we devised cryotherapy by ice balls using Elase (fibrinolysin and deoxyribonuclease, combined). The therapeutic effect of ice-ball cryotherapy was evaluated in 10 patients with carcinoma of the oral cavity and pharynx who were undergoing radiotherapy. Cryotherapy was continued from the development of oral mucositis until its disappearance. The severity of various symptoms of mucositis were reduced by cryotherapy. Healing required 3 to 16 days (median, 7 days) after the end of radiotherapy. Radiotherapy was not interrupted in any cases. This preliminary report suggests that ice-ball cryotherapy is an effective treatment for radiation-induced oral mucositis. (author)

  2. Micro structrual characterization and analysis of ball milled silicon carbide

    Science.gov (United States)

    Madhusudan, B. M.; Raju, H. P.; Ghanaraja., S.

    2018-04-01

    Mechanical alloying has been one of the prominent methods of powder synthesis technique in solid state involving cyclic deformation, cold welding and fracturing of powder particles. Powder particles in this method are subjected to greater mechanical deformation due to the impact of ball-powder-ball and ball-powder-container collisions that occurs during mechanical alloying. Strain hardening and fracture of particles decreases the size of the particles and creates new surfaces. The objective of this Present work is to use ball milling of SiC powder for different duration of 5, 10, 15 and 20 hours by High energy planetary ball milling machine and to evaluate the effect of ball milling on SiC powder. Micro structural Studies using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and EDAX has been investigated.

  3. Formation and collapse of internal transport barrier

    International Nuclear Information System (INIS)

    Fukuyama, A.; Itoh, K.; Itoh, S.I.; Yagi, M.

    1999-01-01

    A theoretical model of internal transport barrier (ITB) is developed. The transport model based on the self-sustained turbulence theory of the current-diffusive ballooning mode is extended to include the effects of ExB rotation shear. Delayed formation of ITB is observed in transport simulations. The influence of finite gyroradius is also discussed. Simulation of the current ramp-up experiment successfully described the radial profile of density, temperature and safety factor. A model of ITB collapse due to magnetic braiding is proposed. Sudden enhancement of transport triggered by overlapping of magnetic islands terminates ITB. The possibility of destabilizing global low-n modes is also discussed. (author)

  4. Formation and collapse of internal transport barrier

    International Nuclear Information System (INIS)

    Fukuyama, A.; Itoh, K.; Itoh, S.-I.; Yagi, M.

    2001-01-01

    A theoretical model of internal transport barrier (ITB) is developed. The transport model based on the self-sustained turbulence theory of the current-diffusive ballooning mode is extended to include the effects of ExB rotation shear. Delayed formation of ITB is observed in transport simulations. The influence of finite gyroradius is also discussed. Simulation of the current ramp-up experiment successfully described the radial profile of density, temperature and safety factor. A model of ITB collapse due to magnetic braiding is proposed. Sudden enhancement of transport triggered by overlaping of magnetic islands terminates ITB. The possibility of destabilizing global low-n modes is also discussed. (author)

  5. Water Bouncing Balls: how material stiffness affects water entry

    Science.gov (United States)

    Truscott, Tadd

    2014-03-01

    It is well known that one can skip a stone across the water surface, but less well known that a ball can also be skipped on water. Even though 17th century ship gunners were aware that cannonballs could be skipped on the water surface, they did not know that using elastic spheres rather than rigid ones could greatly improve skipping performance (yet would have made for more peaceful volleys). The water bouncing ball (Waboba®) is an elastic ball used in a game of aquatic keep away in which players pass the ball by skipping it along the water surface. The ball skips easily along the surface creating a sense that breaking the world record for number of skips could easily be achieved (51 rock skips Russell Byers 2007). We investigate the physics of skipping elastic balls to elucidate the mechanisms by which they bounce off of the water. High-speed video reveals that, upon impact with the water, the balls create a cavity and deform significantly due to the extreme elasticity; the flattened spheres resemble skipping stones. With an increased wetted surface area, a large hydrodynamic lift force is generated causing the ball to launch back into the air. Unlike stone skipping, the elasticity of the ball plays an important roll in determining the success of the skip. Through experimentation, we demonstrate that the deformation timescale during impact must be longer than the collision time in order to achieve a successful skip. Further, several material deformation modes can be excited upon free surface impact. The effect of impact velocity and angle on the two governing timescales and material wave modes are also experimentally investigated. Scaling for the deformation and collision times are derived and used to establish criteria for skipping in terms of relevant physical parameters.

  6. Tracheal collapse in two cats

    International Nuclear Information System (INIS)

    Hendricks, J.C.; O'Brien, J.A.

    1985-01-01

    Two cats examined bronchoscopically to discover the cause of tracheal collapse were found to have tracheal obstruction cranial to the collapse. Cats with this unusual sign should be examined bronchoscopically to ascertain whether there is an obstruction, as the cause in these 2 cats was distinct from the diffuse airway abnormality that causes tracheal collapse in dogs

  7. Evaluation of rolling contact fatigue of induction heated 13Cr-2Ni-2Mo Stainless steel bar with Si3N4-ball

    Science.gov (United States)

    Yadoiwa, Ariyasu; Mizobe, Koshiro; Kida, Katsuyuki

    2018-03-01

    13Cr % martensitic stainless steels were used in various industry, because they have excellent corrosion resistance and high hardness among other stainless steels. They are also expected as a bearing material, however, the research on rolling contact fatigue (RCF) is not enough. In this study, 13Cr-2Ni-2Mo stainless steels were quenched by induction heating and their RCF lives were evaluated. A Si3N4-ball was used in order to apply higher stress (Pmax = 5.6 GPa) than our previous tests (Pmax=5.3 GPa), in a single-ball RCF testing machine. It was found that the basic life (L10) was 2.20×106 cycles and Median life (L50) was 6.04×106 cycles. In addition, Weibull modulus became higher than the previous tests.

  8. BALL KINEMATICS IN FINE POLISHING BETWEEN MISALIGNED DISKS IN CONIC OPENINGS

    Directory of Open Access Journals (Sweden)

    K. G. Shchetnikovich

    2009-01-01

    Full Text Available The paper considers ball kinematics in polishing between misaligned disks rotating with equal angular velocity; one of these disks has conic openings. Analytical dependences have been obtained for calculation of an angular velocity and ball sliding speed in the conic opening. It has been revealed that at a constant contact of a ball with elastic coating of a flat disk and absence of vibrations in the technological system an instantaneous axis of ball rotation does not change its position in the moving ball. It has been ascertained that when a ball is in contact with a flat disk having elastic coating with grooves changes in the position of ball rotation instantaneous axis have a regular character and do not depend on vibrations in the technological system.

  9. The effect of social exclusion on state paranoia and explicit and implicit self-esteem in a non-clinical sample

    OpenAIRE

    Stewart, C.; Rogers, F.; Pilch, M.; Stewart, I.; Barnes-Holmes, Y.; Westermann, S.

    2017-01-01

    Background and objectives:\\ud The relationship between self-esteem and paranoia may be influenced by social stress. This study aimed to replicate previous research on the impact ofsocial exclusion on paranoia and self-esteem in a non-clinical sample and to extend this work by examining the effect of exclusion on self-esteem at the ‘implicit’ level.\\ud \\ud Methods:\\ud Non-clinical participants (N = 85) were randomly allocated to the Inclusion or Exclusion condition of a virtual ball-toss game ...

  10. Anthropometric, biomechanical, and isokinetic strength predictors of ball release speed in high-performance cricket fast bowlers.

    Science.gov (United States)

    Wormgoor, Shohn; Harden, Lois; Mckinon, Warrick

    2010-07-01

    Fast bowling is fundamental to all forms of cricket. The purpose of this study was to identify parameters that contribute to high ball release speeds in cricket fast bowlers. We assessed anthropometric dimensions, concentric and eccentric isokinetic strength of selected knee and shoulder muscle groups, and specific aspects of technique from a single delivery in 28 high-performance fast bowlers (age 22.0 +/- 3.0 years, ball release speed 34.0 +/- 1.3 m s(-1)). Six 50-Hz cameras and the Ariel Performance Analysis System software were used to analyse the fast and accurate deliveries. Using Pearson's correlation, parameters that showed significant associations with ball release speed were identified. The findings suggest that greater front leg knee extension at ball release (r=0.52), shoulder alignment in the transverse plane rotated further away from the batsman at front foot strike (r=0.47), greater ankle height during the delivery stride (r=0.44), and greater shoulder extension strength (r=0.39) contribute significantly to higher ball release speeds. Predictor variables failed to allow their incorporation into a multivariate model, which is known to exist in less accomplished bowlers, suggesting that factors that determine ball release speed found in other groups may not apply to high-performance fast bowlers.

  11. NON-TRADITIONAL SPORTS AT SCHOOL. BENEFITS FOR PHYSICAL AND MOTOR DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    AMADOR J. LARA-SÁNCHEZ

    2010-12-01

    Full Text Available Physical Education teachers have been using some very classic team sports, like football, basketball, handball, volleyball, etc. for many years in order to develop their education work at school. As a consequence of this, the benefits of this kind of activities on Physical Education lessons have not been as notable as we mighthave expected, since, even if they are increasing, their development and application are still low. There are many and very varied new non-traditional sports that have emerged and extended across Spain in recent years. To mention an example, we could refer to a newly created non-traditional sport such as kin-ball. This sport wascreated for the purpose of achieving a way to combine several factors such as health, team-work and competitiveness. Three teams of four players each participate. This way, every player can participate to a great extent in all the moves of the match, for each of them must defend one area of their half in order to achieve a common objective. Besides, kin-ball helps to develop motor skills at school in an easy way; that is, coordination, balance and perception. There is a large variety of non-traditional games and sports that are similar to kin-ball, such as floorball, intercrosse, mazaball, tchoukball, ultimate, indiaca, shuttleball... All of them show many physical, psychic and social advantages, and can help us to make the Physical Education teaching-learning process more motivating, acquiring the recreational component that it showed some years ago and which hasnow disappeared

  12. Multi-stage volcanic island flank collapses with coeval explosive caldera-forming eruptions

    OpenAIRE

    Hunt, James E.; Cassidy, Michael; Talling, Peter J.

    2018-01-01

    Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small (<5 km3) flank collapse on a terrestrial volcano could immediately precede a devastating eruption. The lateral collapse of volcanic island flanks, such as in the Canary Islands, can be far larger (>300 km3), but can also occur in complex multiple stages. Here, we show that multistage retrogressive lands...

  13. Spherical top-hat collapse of a viscous unified dark fluid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei [Bohai University, Department of Physics, Jinzhou (China); Dalian University of Technology, Institute of Theoretical Physics, Dalian (China); Xu, Lixin [Dalian University of Technology, Institute of Theoretical Physics, Dalian (China)

    2014-05-15

    In this paper, we test the spherical collapse of a viscous unified dark fluid (VUDF) which has constant adiabatic sound speed and show the nonlinear collapse for VUDF, baryons, and darkmatter, which are important in forming the large-scale structure of our Universe. By varying the values of the model parameters α and ζ{sub 0}, we discuss their effects on the nonlinear collapse of the VUDF model, and we compare its result to the ΛCDM model. The results of the analysis show that, within the spherical top-hat collapse framework, larger values of α and smaller values of ζ{sub 0} make the structure formation earlier and faster, and the other collapse curves are almost distinguished with the curve of ΛCDM model if the bulk viscosity coefficient ζ{sub 0} is less than 10{sup -3}. (orig.)

  14. Evaluation of the release of dioxins and PCBs during kiln-firing of ball clay.

    Science.gov (United States)

    Broadwater, Kendra; Meeker, John D; Luksemburg, William; Maier, Martha; Garabrant, David; Demond, Avery; Franzblau, Alfred

    2014-01-01

    Ball clay is known to be naturally contaminated with high levels of polychlorinated di-benzo-p-dioxins (PCDDs). This study evaluated the potential for PCDD, polychlorinated dibenzofuran (PCDF) and polychlorinated biphenyl (PCB) release during the kiln firing of ball clay in an art studio. Toxic equivalence (TEQ) were calculated using World Health Organization (WHO) 2005 toxic equivalence factors (TEF) and congener concentrations. Ten bags of commercial ball clay were found to have an average TEQ of 1,370 nanograms/kilogram (ng kg(-1)) dry weight (dw), almost exclusively due to PCDDs (99.98% of TEQ). After firing, none of the 29 dioxin-like analytes was measured above the limits of detection (LOD) in the clay samples. Air samples were taken during firings using both low-flow and high-flow air samplers. Few low-flow air samples contained measurable levels of dioxin congeners above the LOD. The mean TEQ in the high volume air samples ranged from 0.07 pg m(-3) to 0.21 pg m(-3) when firing ball clay, and was 0.11 pg m(-3) when no clay was fired. These concentrations are within the range measured in typical residences and well-controlled industrial settings. The congener profiles in the high-flow air samples differed from the unfired clay; the air samples had a considerable contribution to the TEQ from PCDFs and PCBs. Given that the TEQs of all air samples were very low and the profiles differed from the unfired clay, it is likely that the PCDDs in dry ball clay were destroyed during kiln firing. These results suggest that inhalation of volatilized dioxins during kiln firing of dry ball clay is an unlikely source of exposure for vocational and art ceramicists. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. THE INFLUENCE OF BALL VELOCITY AND COURT ILLUMINATION ON REACTION TIME FOR TENNIS VOLLEY

    Directory of Open Access Journals (Sweden)

    Jui-hung Tu

    2010-03-01

    Full Text Available The he purpose of this study is to examine the effects of ball velocity, court illumination, and volley type on the reaction time (RT of a tennis athlete for a volley stroke. Eights cases with two different ball velocities (high and low, two volley types (forehand and backhand and two court illumination levels (dark and bright were studied. The 30 participating subjects consisted of 18 male and 12 female college tennis athletes (age: 24 ± 3.2 yr, with a United States Tennis Association (USTA ranking above 2.5. In order to ensure the validity of real-world correlations, the experiments were designed to simulate real competition situations. Reaction times were measured for volley strokes in response to different approaching ball velocities (high: 25.05 ± 0.37 m/s and low: 17.56 ± 0.92 m·s-1 for several volley types (forehand and backhand and court illumination levels (55649 ± 4292 lux and 363.24 ± 6.53 lux on the court. During the tests, the signals from an electromyogram sensor and a 3-axis accelerometer (± 50 g were recorded using an NI DAQ card (NI PXI-6251 and then analyzed to determine reaction time (RT, premotor reaction time (PRT, and motor reaction time (MRT through the LabVIEW system. Subsequent 3-way ANOVA analysis indicated no RT, PRT, or MRT interaction between ball velocity, volley type and illumination. The ball velocity and illumination parameters did affect RT and PRT values significantly with p < 0.05, no significant variation in MRT was observed across any implemented experimental conditions. All experimental results indicate that ball velocity and illumination levels strongly affect the value of PRT, but have no significant effect on the value of MRT, the changes in RT were dominated by PRT

  16. Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Li

    2011-05-04

    In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

  17. A comparison of plastic collapse and limit loads for single mitred pipe bends under in-plane bending

    International Nuclear Information System (INIS)

    Neilson, R.; Wood, J.; Hamilton, R.; Li, H.

    2010-01-01

    This paper presents a comparison of the plastic collapse loads from experimental in-plane bending tests on three 90 o single un-reinforced mitred pipe bends, with the results from various 3D solid finite element models. The bending load applied reduced the bend angle and in turn, the resulting cross-sectional ovalisation led to a recognised weakening mechanism. In addition, at maximum load there was a reversal in stiffness, characteristic of buckling. This reversal in stiffness was accompanied by significant ovalisation and plasticity at the mitre intersection. Both the weakening mechanism and the post-buckling behaviour are only observable by testing or by including large displacement effects in the plastic finite element solution. A small displacement limit solution with an elastic-perfectly plastic material model overestimated the collapse load by more than 40% and could not reproduce the buckling behaviour. The plastic collapse finite element solution, with large displacements, produced excellent agreement with the experiment. Sufficient experimental detail is presented for these results to be used as a benchmark for analysts in this area. Given the robustness of non-linear solutions in commercial finite element codes and the ready availability of computing resources, it is argued that pressure vessel code developers should now be recommending large displacement analysis as the default position for limit and plastic collapse analyses, rather than expecting engineers to anticipate weakening mechanisms and related non-linear phenomena.

  18. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  19. Static end-expiratory and dynamic forced expiratory tracheal collapse in COPD

    International Nuclear Information System (INIS)

    O'Donnell, C.R.; Bankier, A.A.; O'Donnell, D.H.; Loring, S.H.; Boiselle, P.M.

    2014-01-01

    Aim: To determine the range of tracheal collapse at end-expiration among chronic obstructive pulmonary disease (COPD) patients and to compare the extent of tracheal collapse between static end-expiratory and dynamic forced-expiratory multidetector-row computed tomography (MDCT). Materials and methods: After institutional review board approval and obtaining informed consent, 67 patients meeting the National Heart, Lung, and Blood Institute (NHLBI)/World Health Organization (WHO) Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD were sequentially imaged using a 64-detector-row CT machine at end-inspiration, during forced expiration, and at end-expiration. Standardized respiratory coaching and spirometric monitoring were employed. Mean percentage tracheal collapse at end-expiration and forced expiration were compared using correlation analysis, and the power of end-expiratory cross-sectional area to predict excessive forced-expiratory tracheal collapse was computed following construction of receiver operating characteristic (ROC) curves. Results: Mean percentage expiratory collapse among COPD patients was 17 ± 18% at end-expiration compared to 62 ± 16% during forced expiration. Over the observed range of end-expiratory tracheal collapse (approximately 10–50%), the positive predictive value of end-expiratory collapse to predict excessive (≥80%) forced expiratory tracheal collapse was <0.3. Conclusion: COPD patients demonstrate a wide range of end-expiratory tracheal collapse. The magnitude of static end-expiratory tracheal collapse does not predict excessive dynamic expiratory tracheal collapse

  20. Micro sized implantable ball lens-based fiber optic probe design

    Science.gov (United States)

    Cha, Jaepyeong; Kang, Jin U.

    2014-02-01

    A micro sized implantable ball lens-based fiber optic probe design is described for continuous monitoring of brain activity in freely behaving mice. A prototype uses a 500-micron ball lens and a highly flexible 350-micron-diameter fiber bundle, which are enclosed by a 21G stainless steel sheath. Several types and thickness of brain tissue, consisting of fluorescent probes such as GFP, GCaMP3 calcium indicator, are used to evaluate the performance of the imaging probe. Measured working distance is approximately 400-μm, but is long enough to detect neural activities from cortical and cerebellar tissues of mice brain.

  1. Pilot study of ice-ball cryotherapy for radiation-induced oral mucositis

    Energy Technology Data Exchange (ETDEWEB)

    Ohyama, Waichiro; Ebihara, Satoshi [National Cancer Center Hospital, Tokyo (Japan)

    1996-02-01

    Oral mucositis caused by radiotherapy is intractable and may worsen the patient`s nutritional condition and interrupt treatment. To reduce the incidence and severity of oral mucositis induced by cancer therapy and promote early improvement of its symptoms, we devised cryotherapy by ice balls using Elase (fibrinolysin and deoxyribonuclease, combined). The therapeutic effect of ice-ball cryotherapy was evaluated in 10 patients with carcinoma of the oral cavity and pharynx who were undergoing radiotherapy. Cryotherapy was continued from the development of oral mucositis until its disappearance. The severity of various symptoms of mucositis were reduced by cryotherapy. Healing required 3 to 16 days (median, 7 days) after the end of radiotherapy. Radiotherapy was not interrupted in any cases. This preliminary report suggests that ice-ball cryotherapy is an effective treatment for radiation-induced oral mucositis. (author).

  2. Collapse of large extra dimensions

    International Nuclear Information System (INIS)

    Geddes, James

    2002-01-01

    In models of spacetime that are the product of a four-dimensional spacetime with an 'extra' dimension, there is the possibility that the extra dimension will collapse to zero size, forming a singularity. We ask whether this collapse is likely to destroy the spacetime. We argue, by an appeal to the four-dimensional cosmic censorship conjecture, that--at least in the case when the extra dimension is homogeneous--such a collapse will lead to a singularity hidden within a black string. We also construct explicit initial data for a spacetime in which such a collapse is guaranteed to occur and show how the formation of a naked singularity is likely avoided

  3. Structural and magnetic properties of ball milled copper ferrite

    DEFF Research Database (Denmark)

    Goya, G.F.; Rechenberg, H.R.; Jiang, Jianzhong

    1998-01-01

    The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces....... The canted spin configuration is also suggested by the observed reduction in magnetization of particles in the blocked state. Upon increasing the milling time, nanometer-sized CuFe2O4 particles decompose, forming alpha-Fe2O3 and other phases, causing a further decrease of magnetization. After a milling time...... of 98 h, alpha-Fe2O3 is reduced to Fe3O4, and magnetization increases accordingly to the higher saturation magnetization value of magnetite. Three sequential processes during high-energy ball milling are established: (a) the synthesis of partially inverted CuFe2O4 particles with a noncollinear spin...

  4. Evaluation of safety balls and faceguards for prevention of injuries in youth baseball.

    Science.gov (United States)

    Marshall, Stephen W; Mueller, Frederick O; Kirby, Daniel P; Yang, Jingzhen

    2003-02-05

    Safety balls and faceguards are widely used in youth baseball, but their effectiveness in reducing injury is unknown. To evaluate the association of the use of faceguards and safety balls and injuries in youth baseball. Ecological study using a national database of compensated insurance claims maintained by Little League Baseball Incorporated, combined with data on the number of participants in Little League and data from a census of protective equipment usage for youth aged 5 to 18 years participating in Little League Baseball in the United States during 1997-1999. Rate of injury and injury rate ratio comparing users with nonusers of protective equipment. A total of 6 744 240 player-seasons of follow-up and 4233 compensated injury claims were available for analysis. The absolute incidence of compensated injury per 100 000 player-seasons was 28.02 (95% confidence interval [CI], 26.76-29.29) for ball-related injury and 2.71 (95% CI, 2.32-3.11) for facial injury. Overall, use of safety balls was associated with a reduced risk of ball-related injury (adjusted rate ratio, 0.77; 95% CI, 0.64-0.93). This reduction was essentially due to 1 type of safety ball, known as the reduced-impact ball (adjusted rate ratio, 0.72; 95% CI, 0.57-0.91). Use of faceguards reduced the risk of facial injury (adjusted rate ratio, 0.65; 95% CI, 0.43-0.98). Metal and plastic guards appeared to be equally effective. Safety balls appeared to be more effective in the minor division (ages 7-12 years) than in the regular division (ages 9-12 years). Reduced-impact balls and faceguards were associated with a reduced risk of injury in youth baseball. These findings support increased usage of these items; however, it should be noted that the absolute incidence of injury in youth baseball is low and that these equipment items do not prevent all injuries.

  5. Non-destructive examinations of D247.01 SiC-ball. Gamma scan wires 1 and 2 and SiC-ball 1 through 7

    Energy Technology Data Exchange (ETDEWEB)

    Dassel, G.; Buurveld, H.A.; Plakman, J.C.

    1996-07-01

    In the frame of the KFA programme on Innovative Nuclear Technology SiC-coated graphite spheres have been irradiated in the HFR Petten. With this irradiation two stainless steel gamma scan wires have been irradiated to be able to reconstruct the neutron flux profile during the irradiation and to calculate the absorption of neutrons in the spheres. This report presents the results from the gamma scanning of the two gamma scan wires. Appended are the results from dose rate measurements and weighing of the spheres and gamma spectrometric results from balls 5 and 6. (orig.).

  6. Non-destructive examinations of D247.01 SiC-ball. Gamma scan wires 1 and 2 and SiC-ball 1 through 7

    International Nuclear Information System (INIS)

    Dassel, G.; Buurveld, H.A.; Plakman, J.C.

    1996-07-01

    In the frame of the KFA programme on Innovative Nuclear Technology SiC-coated graphite spheres have been irradiated in the HFR Petten. With this irradiation two stainless steel gamma scan wires have been irradiated to be able to reconstruct the neutron flux profile during the irradiation and to calculate the absorption of neutrons in the spheres. This report presents the results from the gamma scanning of the two gamma scan wires. Appended are the results from dose rate measurements and weighing of the spheres and gamma spectrometric results from balls 5 and 6. (orig.)

  7. Stability of a Fermi ball against deformation from spherical shape

    International Nuclear Information System (INIS)

    Yoshida, T.; Ogure, K.; Arafune, J.

    2003-01-01

    The stability of a Fermi ball (F ball), which is a kind of nontopological soliton accompanying the breakdown of the approximate Z 2 symmetry, is investigated in three situations: when it is electrically neutral, when it is electrically charged and unscreened, and when it is electrically charged and screened. We argue only that the third case is physically meaningful since the neutral F ball is unstable and the case of an unscreened charged F ball is observationally excluded when it has a sizable contribution to CDM. We find that the energy scale of the breakdown of the approximate Z 2 symmetry v should satisfy v 6 GeV if the F ball is the main component of CDM

  8. Soccer Ball Lift Coefficients via Trajectory Analysis

    Science.gov (United States)

    Goff, John Eric; Carre, Matt J.

    2010-01-01

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…

  9. The effect of intermediate stop and ball size in fabrication of recycled steel powder using ball milling from machining steel chips

    International Nuclear Information System (INIS)

    Fitri, M.W.M.; Shun, C.H.; Rizam, S.S.; Shamsul, J.B.

    2007-01-01

    A feasibility study for producing recycled steel powder from steel scrap by ball milling was carried out. Steel scrap from machining was used as a raw material and was milled using planetary ball milling. Three samples were prepared in order to study the effect of intermediate stop and ball size. Sample with intermediate stop during milling process showed finer particle size compared to the sample with continuous milling. Decrease in the temperature of the vial during the intermediate stop milling gives less ductile behaviour to the steel powder, which is then easily work-hardened and fragmented to fine powder. Mixed small and big size ball give the best production of recycled steel powder where it gives higher impact force to the scrap and accelerate the fragmentation of the steel scrap into powder. (author)

  10. Influence of Tennis Racquet Kinematics on Ball Topspin Angular Velocity and Accuracy during the Forehand Groundstroke.

    Science.gov (United States)

    Kwon, Sunku; Pfister, Robin; Hager, Ronald L; Hunter, Iain; Seeley, Matthew K

    2017-12-01

    Forehand groundstroke effectiveness is important for tennis success. Ball topspin angular velocity (TAV) and accuracy are important for forehand groundstroke effectiveness, and have been extensively studied, previously; despite previous, quality studies, it was unclear whether certain racquet kinematics relate to ball TAV and shot accuracy during the forehand groundstroke. This study evaluated potential relationships between (1) ball TAV and (2) forehand accuracy, and five measures of racquet kinematics: racquet head impact angle (i.e., closed or open face), horizontal and vertical racquet head velocity before impact, racquet head trajectory (resultant velocity direction, relative to horizontal) before impact, and hitting zone length (quasi-linear displacement, immediately before and after impact). Thirteen collegiate-level tennis players hit forehand groundstrokes in a biomechanics laboratory, where racquet kinematics and ball TAV were measured, and on a tennis court, to assess accuracy. Correlational statistics were used to evaluate potential relationships between racquet kinematics, and ball TAV (mixed model) and forehand accuracy (between-subjects model; α = 0.05). We observed an average (1) racquet head impact angle, (2) racquet head trajectory before impact, relative to horizontal, (3) racquet head horizontal velocity before impact, (4) racquet head vertical velocity before impact, and (5) hitting zone length of 80.4 ± 3.6˚, 18.6 ± 4.3˚, 15.4 ± 1.4 m·s -1 , 6.6 ± 2.2 m·s -1 , and 79.8 ± 8.6 mm, respectively; and an average ball TAV of 969 ± 375 revolutions per minute. Only racquet head impact angle and racquet head vertical velocity, before impact, significantly correlated with ball TAV (p < 0.01). None of the observed racquet kinematics significantly correlated to the measures of forehand accuracy. These results confirmed mechanical logic and indicate that increased ball TAV is associated with a more closed racquet head impact angle (ranging from

  11. Influence of Tennis Racquet Kinematics on Ball Topspin Angular Velocity and Accuracy during the Forehand Groundstroke

    Directory of Open Access Journals (Sweden)

    Sunku Kwon, Robin Pfister, Ronald L. Hager, Iain Hunter, Matthew K. Seeley

    2017-12-01

    Full Text Available Forehand groundstroke effectiveness is important for tennis success. Ball topspin angular velocity (TAV and accuracy are important for forehand groundstroke effectiveness, and have been extensively studied, previously; despite previous, quality studies, it was unclear whether certain racquet kinematics relate to ball TAV and shot accuracy during the forehand groundstroke. This study evaluated potential relationships between (1 ball TAV and (2 forehand accuracy, and five measures of racquet kinematics: racquet head impact angle (i.e., closed or open face, horizontal and vertical racquet head velocity before impact, racquet head trajectory (resultant velocity direction, relative to horizontal before impact, and hitting zone length (quasi-linear displacement, immediately before and after impact. Thirteen collegiate-level tennis players hit forehand groundstrokes in a biomechanics laboratory, where racquet kinematics and ball TAV were measured, and on a tennis court, to assess accuracy. Correlational statistics were used to evaluate potential relationships between racquet kinematics, and ball TAV (mixed model and forehand accuracy (between-subjects model; α = 0.05. We observed an average (1 racquet head impact angle, (2 racquet head trajectory before impact, relative to horizontal, (3 racquet head horizontal velocity before impact, (4 racquet head vertical velocity before impact, and (5 hitting zone length of 80.4 ± 3.6˚, 18.6 ± 4.3˚, 15.4 ± 1.4 m·s-1, 6.6 ± 2.2 m·s-1, and 79.8 ± 8.6 mm, respectively; and an average ball TAV of 969 ± 375 revolutions per minute. Only racquet head impact angle and racquet head vertical velocity, before impact, significantly correlated with ball TAV (p < 0.01. None of the observed racquet kinematics significantly correlated to the measures of forehand accuracy. These results confirmed mechanical logic and indicate that increased ball TAV is associated with a more closed racquet head impact angle (ranging

  12. Health and Physiological Adaptations of Small-Sided Ball Games in Untrained Older Adults Aged 65-93 Years

    DEFF Research Database (Denmark)

    Vorup Petersen, Jacob

    function, and 3) the feasibility, motivation and injury rate of regular small-sided ball games in untrained elderly. Purpose. The overall aims of the present thesis were to examine physiological adaptations important for health after a period of small-sided ball game training and protein ingestion...... adults, 16 weeks of small-sided soccer was shown to improve physical function and exercise capacity, whereas muscle mass was unaffected by the training despite a high intake of daily protein. However, a number of questions still need to be answered regarding small-sided ball game training in untrained...... elderly: 1) The effect of other small-sided ball games, e.g. floorball training and cone ball, on physiological adaptations important for health as well as the effect of combined protein intake, 2) the effect of regular small-sided ball games in older adults with a more advanced age and low physical...

  13. Effect of Ball Weight on Speed, Accuracy, and Mechanics in Cricket Fast Bowling

    Directory of Open Access Journals (Sweden)

    Katharine L. Wickington

    2017-02-01

    Full Text Available The aims of this study were: (1 to quantify the acute effects of ball weight on ball release speed, accuracy, and mechanics in cricket fast bowling; and (2 to test whether a period of sustained training with underweight and overweight balls is effective in increasing a player’s ball release speed. Ten well-trained adult male cricket players performed maximum-effort deliveries using balls ranging in weight from 46% to 137% of the standard ball weight (156 g. A radar gun, bowling target, and 2D video analysis were used to obtain measures of ball speed, accuracy, and mechanics. The participants were assigned to either an intervention group, who trained with underweight and overweight balls, or to a control group, who trained with standard-weight balls. We found that ball speed decreased at a rate of about 1.1 m/s per 100 g increase in ball weight. Accuracy and bowling mechanics were not adversely affected by changes in ball weight. There was evidence that training with underweight and overweight balls might have produced a practically meaningful increase in bowling speed (>1.5 m/s in some players without compromising accuracy or increasing their risk of injury through inducing poor bowling mechanics. In cricket fast bowling, a wide range of ball weight might be necessary to produce an effective modified-implement training program.

  14. 48 CFR 225.7009 - Restriction on ball and roller bearings.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Restriction on ball and roller bearings. 225.7009 Section 225.7009 Federal Acquisition Regulations System DEFENSE ACQUISITION... roller bearings. ...

  15. Visualization of air flow around soccer ball using a particle image velocimetry

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi; Seo, Kazuya

    2015-10-01

    A traditional soccer ball is constructed using 32 pentagonal and hexagonal panels. In recent years, however, the likes of the Teamgeist and Jabulani balls, constructed from 14 and 8 panels, respectively, have entered the field, marking a significant departure from conventionality in terms of shape and design. Moreover, the recently introduced Brazuca ball features a new 6-panel design and has already been adopted by many soccer leagues. However, the shapes of the constituent panels of these balls differ substantially from those of conventional balls. Therefore, this study set out to investigate the flight and aerodynamic characteristics of different orientations of the soccer ball, which is constructed from panels of different shapes. A wind tunnel test showed substantial differences in the aerodynamic forces acting on the ball, depending on its orientation. Substantial differences were also observed in the aerodynamic forces acting on the ball in different directions, corresponding to its orientation and rotation. Moreover, two-dimensional particle image velocimetry (2D-PIV) measurements showed that the boundary separation varies depending on the orientation of the ball. Based on these results, we can conclude that the shape of the panels of a soccer ball substantially affects its flight trajectory.

  16. The effect of extreme ionization rates during the initial collapse of a molecular cloud core

    Science.gov (United States)

    Wurster, James; Bate, Matthew R.; Price, Daniel J.

    2018-05-01

    What cosmic ray ionization rate is required such that a non-ideal magnetohydrodynamics (MHD) simulation of a collapsing molecular cloud will follow the same evolutionary path as an ideal MHD simulation or as a purely hydrodynamics simulation? To investigate this question, we perform three-dimensional smoothed particle non-ideal MHD simulations of the gravitational collapse of rotating, one solar mass, magnetized molecular cloud cores, which include Ohmic resistivity, ambipolar diffusion, and the Hall effect. We assume a uniform grain size of ag = 0.1 μm, and our free parameter is the cosmic ray ionization rate, ζcr. We evolve our models, where possible, until they have produced a first hydrostatic core. Models with ζcr ≳ 10-13 s-1 are indistinguishable from ideal MHD models, and the evolution of the model with ζcr = 10-14 s-1 matches the evolution of the ideal MHD model within 1 per cent when considering maximum density, magnetic energy, and maximum magnetic field strength as a function of time; these results are independent of ag. Models with very low ionization rates (ζcr ≲ 10-24 s-1) are required to approach hydrodynamical collapse, and even lower ionization rates may be required for larger ag. Thus, it is possible to reproduce ideal MHD and purely hydrodynamical collapses using non-ideal MHD given an appropriate cosmic ray ionization rate. However, realistic cosmic ray ionization rates approach neither limit; thus, non-ideal MHD cannot be neglected in star formation simulations.

  17. The synthesis of Cu/Fe/Fe3O4 catalyst through the aqueous solution ball milling method assisted by high-frequency electromagnetic field

    Science.gov (United States)

    Yingzhe, Zhang; Yuxing, He; Qingdong, Qin; Fuchun, Wang; Wankun, Wang; Yongmei, Luo

    2018-06-01

    In this paper, nano-magnetic Cu/Fe/Fe3O4 catalyst was prepared by a new aqueous solution ball milling method assisted by high-frequency electromagnetic field at room temperature. The products were characterized by means of X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and vibrating sample magnetometer (VSM). Microwave induced catalytic degradation of methylene blue (MB) was carried out in the presence of Cu/Fe/Fe3O4. The concentration of methylene blue was determined by UV-Vis spectrophotometry. The solid catalyst showed high catalytic activity of degrade MB and considerable saturation magnetization, lower remanence and coercivity. It indicate that the catalyst can be effectively separated for reuse by simply applying an external magnetic field and it can greatly promote their potential industrial application to eliminate organic pollutants from waste-water. Finally, we found that it is the non-thermal effect of microwave that activated the catalytic activity of Cu/Fe/Fe3O4 to degrade MB.

  18. Multidimensional simulations of core-collapse supernovae with CHIMERA

    Science.gov (United States)

    Lentz, Eric J.; Bruenn, S. W.; Yakunin, K.; Endeve, E.; Blondin, J. M.; Harris, J. A.; Hix, W. R.; Marronetti, P.; Messer, O. B.; Mezzacappa, A.

    2014-01-01

    Core-collapse supernovae are driven by a multidimensional neutrino radiation hydrodynamic (RHD) engine, and full simulation requires at least axisymmetric (2D) and ultimately symmetry-free 3D RHD simulation. We present recent and ongoing work with our multidimensional RHD supernova code CHIMERA to understand the nature of the core-collapse explosion mechanism and its consequences. Recently completed simulations of 12-25 solar mass progenitors(Woosley & Heger 2007) in well resolved (0.7 degrees in latitude) 2D simulations exhibit robust explosions meeting the observationally expected explosion energy. We examine the role of hydrodynamic instabilities (standing accretion shock instability, neutrino driven convection, etc.) on the explosion dynamics and the development of the explosion energy. Ongoing 3D and 2D simulations examine the role that simulation resolution and the removal of the imposed axisymmetry have in the triggering and development of an explosion from stellar core collapse. Companion posters will explore the gravitational wave signals (Yakunin et al.) and nucleosynthesis (Harris et al.) of our simulations.

  19. Fabrication of lanthanum-doped thorium dioxide by high-energy ball milling and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Spencer M.; Yao, Tiankai [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Lu, Fengyuan [Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Xin, Guoqing; Zhu, Weiguang [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Lian, Jie, E-mail: lianj@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States)

    2017-03-15

    Abstract: High-energy ball milling was used to synthesize Th{sub 1-x}La{sub x}O{sub 2-0.5x} (x = 0.09, 0.23) solid solutions, as well as improve the sinterability of ThO{sub 2} powders. Dense La-doped ThO{sub 2} pellets with theoretical density above 94% were consolidated by spark plasma sintering at temperatures above 1400 °C for 20 min, and the densification behavior and the non-equilibrium effects on phase and structure were investigated. A lattice contraction of the SPS-densified pellets occurred with increasing ball milling duration, and a secondary phase with increased La-content was observed in La-doped pellets. A dependence on the La-content and sintering duration for the onset of localized phase segregation has been proposed. The effects of high-energy ball milling, La-content, and phase formation on the thermal diffusivity were also studied for La-doped ThO{sub 2} pellets by laser flash measurement. Increasing La-content and high energy ball milling time decreases thermal diffusivity; while the sintering peak temperature and holding time beyond 1600 °C dramatically altered the temperature dependence of the thermal diffusivity beyond 600 °C. - Highlights: • Lanthanum incorporation into ThO{sub 2} by high energy ball milling and rapid consolidation by spark plasma sintering. • Elucidation of phase behavior of the La-doped ThO{sub 2} and the contributions of La incorporation and SPS sintering conditions. • Investigation of the effects of La incorporation and high energy ball milling on the thermal behavior of La-doped ThO{sub 2}.

  20. A study on the noise characteristics of polymer ball bearings under various lubrication conditions

    Science.gov (United States)

    Dinç, S. K.; Temiz, V.; Kamburoǧlu, E.

    2013-12-01

    Polymer bearings are generally praised by the manufacturers for running silently. However such statements never go beyond qualitative assumptions. Therefore, studying polymer ball bearing noise would have been meaningful solely on the perspective of silent running machinery. On the other hand, the service life of a polymer ball bearing is unpredictable and there's no preventive maintenance practice that provides data regarding the condition of a polymer ball bearing. In this study, we assume that an investigation of their noise characteristics could also reveal clues concerning their performances. The main objective of this study is to determine the noise characteristics of polymer ball bearings lubricated with different lubricant greases of varying viscosity grades through experimental means. Sound pressure level measurements of SKF brand polymer bearings with polypropylene rings, polypropylene cage and glass balls were made with a 1/2 inch microphone in 1/3-octave bands, at frequencies up to 12.5 kHz, under various radial loads and rotational speeds. The bearings were mounted on a shaft driven by an AC motor with stepless speed control, adjustable between 0 - 1400 rpm. The ball bearings were running inside an acoustic chamber designed for the insulation of environmental noise and the noise of the motor at target frequencies. The resulting sound pressure level spectra were evaluated and the effects of the lubrication conditions on the noise of the ball bearing and possible diagnostic insight that could be gained through studying bearing noise characteristics were discussed.

  1. Assessment of head injury of children due to golf ball impact.

    Science.gov (United States)

    Lee, Heow Pueh; Wang, Fang

    2010-10-01

    Head trauma injury due to impact by a flying golf ball is one of the most severe possible injury accidents on the golf course. Numerical simulations based on the finite element method are presented to investigate head injury in children due to impact by a flying golf ball. The stress and energy flow patterns in a head model during the golf ball impact are computed for various combinations of striking speed, falling angle of the golf ball before impact, and impact location. It is found that a child is more prone to head injury due to golf ball impact on the frontal and side/temporal areas. The simulated results are found to conform to the clinical reports on children's head injuries from flying golf balls.

  2. Gravitational collapse and evolution of holographic black holes

    Energy Technology Data Exchange (ETDEWEB)

    Casadio, R [Dipartimento di Fisica, Universita di Bologna and I.N.F.N., Sezione di Bologna, via Irnerio 46, 40126 Bologna (Italy); Germani, C [D.A.M.T.P., Centre for Mathematical Sciences, University of Cambridge, Wilberforce road, Cambridge CB3 0WA (United Kingdom)

    2006-03-01

    Gravitational collapse is analyzed in the Brane-World by arguing that regularity of five-dimensional geodesics require that stars on the brane have an atmosphere. For the simple case of a spherically symmetric cloud of non-dissipating dust, conditions are found for which the collapsing star evaporates and approaches the Hawking behavior as the (apparent) horizon is being formed. The effective energy of the star vanishes at a finite radius and the star afterwards re-expands and 'anti-evaporates'. Israel junction conditions across the brane (holographically related to the matter trace anomaly) and the projection of the Weyl tensor on the brane (holographically interpreted as the quantum back-reaction on the brane metric) contribute to the total energy as, respectively, an 'anti-evaporation' and an 'evaporation' term.

  3. High-resolution simulations of cylindrical void collapse in energetic materials: Effect of primary and secondary collapse on initiation thresholds

    Science.gov (United States)

    Rai, Nirmal Kumar; Schmidt, Martin J.; Udaykumar, H. S.

    2017-04-01

    Void collapse in energetic materials leads to hot spot formation and enhanced sensitivity. Much recent work has been directed towards simulation of collapse-generated reactive hot spots. The resolution of voids in calculations to date has varied as have the resulting predictions of hot spot intensity. Here we determine the required resolution for reliable cylindrical void collapse calculations leading to initiation of chemical reactions. High-resolution simulations of collapse provide new insights into the mechanism of hot spot generation. It is found that initiation can occur in two different modes depending on the loading intensity: Either the initiation occurs due to jet impact at the first collapse instant or it can occur at secondary lobes at the periphery of the collapsed void. A key observation is that secondary lobe collapse leads to large local temperatures that initiate reactions. This is due to a combination of a strong blast wave from the site of primary void collapse and strong colliding jets and vortical flows generated during the collapse of the secondary lobes. The secondary lobe collapse results in a significant lowering of the predicted threshold for ignition of the energetic material. The results suggest that mesoscale simulations of void fields may suffer from significant uncertainty in threshold predictions because unresolved calculations cannot capture the secondary lobe collapse phenomenon. The implications of this uncertainty for mesoscale simulations are discussed in this paper.

  4. The development of cobalt-base alloy ball bearing

    International Nuclear Information System (INIS)

    Yu Xinshui; Chen Jianting; Wang Zaishu; Wang Ximei; Huang Chongming.

    1986-01-01

    The main technologies and experiences in developing a Cobalt-base alloy ball bearing are described. In the hardfacing of bearing races, a lower-hardness alloy of type St-6 is used rather than an alloy with hardness similar to that of the ball and finally the hardness of race is increased to match that of the ball by heat treatment. This improvement has certain advantages. The experience of whole developing technology indicates that strict control of the technology in the bearing-race hardfacing is the key problem in the quality assurance of bearings

  5. Velocity structure of protostellar envelopes: gravitational collapse and rotation

    International Nuclear Information System (INIS)

    Belloche, Arnaud

    2002-01-01

    Stars form from the gravitational collapse of pre-stellar condensations in molecular clouds. The major aim of this thesis is to compare the predictions of collapse models with observations of both very young (class 0) protostars and starless condensations in millimeter molecular lines. We wish to understand what determines the masses of forming stars and whether the initial conditions have an effect on the dynamical evolution of a condensation. Using a Monte-Carlo radiative transfer code, we analyze rotation and infall spectroscopic signatures to study the velocity structure of a sample of protostellar condensations. We show that the envelope of the class 0 protostar IRAM 04191 in the Taurus molecular cloud is undergoing both extended, subsonic infall and fast, differential rotation. We propose that the inner part of the envelope is a magnetically supercritical core in the process of decoupling from the ambient cloud still supported by the magnetic field. We suggest that the kinematical properties observed for IRAM 04191 are representative of the physical conditions characterizing isolated protostars shortly after point mass formation. On the other hand, a similar study for the pre-stellar condensations of the Rho Ophiuchi proto-cluster yields mass accretion rates that are an order of magnitude higher than in IRAM 04191. This suggests that individual protostellar collapse in clusters is induced by external disturbances. Moreover, we show that the condensations do not have time to orbit significantly through the proto-cluster gas before evolving into protostars and pre-main-sequence stars. This seems inconsistent with models which resort to dynamical interactions and competitive accretion to build up a mass spectrum comparable to the stellar initial mass function. We conclude that protostellar collapse is nearly spontaneous in regions of isolated star formation such as the Taurus cloud but probably strongly induced in proto-clusters. (author) [fr

  6. Predicting mining collapse: Superjerks and the appearance of record-breaking events in coal as collapse precursors

    Science.gov (United States)

    Jiang, Xiang; Liu, Hanlong; Main, Ian G.; Salje, Ekhard K. H.

    2017-08-01

    The quest for predictive indicators for the collapse of coal mines has led to a robust criterion from scale-model tests in the laboratory. Mechanical collapse under uniaxial stress forms avalanches with a power-law probability distribution function of radiated energy P ˜E-ɛ , with exponent ɛ =1.5 . Impending major collapse is preceded by a reduction of the energy exponent to the mean-field value ɛ =1.32 . Concurrently, the crackling noise increases in intensity and the waiting time between avalanches is reduced when the major collapse is approaching. These latter criteria were so-far deemed too unreliable for safety assessments in coal mines. We report a reassessment of previously collected extensive collapse data sets using "record-breaking analysis," based on the statistical appearance of "superjerks" within a smaller spectrum of collapse events. Superjerks are defined as avalanche signals with energies that surpass those of all previous events. The final major collapse is one such superjerk but other "near collapse" events equally qualify. In this way a very large data set of events is reduced to a sparse sequence of superjerks (21 in our coal sample). The main collapse can be anticipated from the sequence of energies and waiting times of superjerks, ignoring all weaker events. Superjerks are excellent indicators for the temporal evolution, and reveal clear nonstationarity of the crackling noise at constant loading rate, as well as self-similarity in the energy distribution of superjerks as a function of the number of events so far in the sequence Es j˜nδ with δ =1.79 . They are less robust in identifying the precise time of the final collapse, however, than the shift of the energy exponents in the whole data set which occurs only over a short time interval just before the major event. Nevertheless, they provide additional diagnostics that may increase the reliability of such forecasts.

  7. Collapse and equilibrium of rotating, adiabatic clouds

    International Nuclear Information System (INIS)

    Boss, A.P.

    1980-01-01

    A numerical hydrodynamics computer code has been used to follow the collapse and establishment of equilibrium of adiabatic gas clouds restricted to axial symmetry. The clouds are initially uniform in density and rotation, with adiabatic exponents γ=5/3 and 7/5. The numerical technique allows, for the first time, a direct comparison to be made between the dynamic collapse and approach to equilibrium of unconstrained clouds on the one hand, and the results for incompressible, uniformly rotating equilibrium clouds, and the equilibrium structures of differentially rotating polytropes, on the other hand

  8. Postmatch recovery of physical performance and biochemical markers in team ball sports : a systematic review

    NARCIS (Netherlands)

    Doeven, Steven H; Brink, Michel S; Kosse, Silke J; Lemmink, Koen A P M

    2018-01-01

    Background: Insufficient postmatch recovery in elite players may cause an increased risk of injuries, illnesses and non-functional over-reaching. Objective: To evaluate postmatch recovery time courses of physical performance and biochemical markers in team ball sport players. Study design:

  9. Math Academy: Play Ball! Explorations in Data Analysis & Statistics. Book 3: Supplemental Math Materials for Grades 3-8

    Science.gov (United States)

    Rimbey, Kimberly

    2008-01-01

    Created by teachers for teachers, the Math Academy tools and activities included in this booklet were designed to create hands-on activities and a fun learning environment for the teaching of mathematics to the students. This booklet contains the "Math Academy--Play Ball! Explorations in Data Analysis & Statistics," which teachers can use to…

  10. Launch Creativity with Ping-Pong Ball Challenge

    Science.gov (United States)

    Kornoelje, Joanne; Roman, Harry T.

    2011-01-01

    Educators at Thomas A. Edison Middle School have worked together to bring invention information and activities to life. One activity in particular, Ping-Pong Ball Invention Challenge, has proven a great success. The Ping-Pong Ball Invention Challenge was inspired by the basic rules for PBS's "Design Squad"'s "Pop Fly" activity. In this article,…

  11. Nonlinear dynamic model for skidding behavior of angular contact ball bearings

    Science.gov (United States)

    Han, Qinkai; Chu, Fulei

    2015-10-01

    A three-dimensional nonlinear dynamic model is proposed to predict the skidding behavior of angular contact ball bearings under combined load condition. The centrifugal and gyroscopic effects induced by ball rotation and revolution, Hertz contact between the ball and inner/outer races, discontinuous contact between the ball and cage and elastohydrodynamic lubrication are considered in the model. Through comparisons with the tested results of the reference, the dynamic model is verified. Based upon these, variations of ball slipping speed with time and space are discussed for the bearing under combined load condition. It is shown that radial load leads to the fluctuations in the slipping velocity of the ball contacting with inner/outer races, especially for the ball in load-decreasing regions. Adding the radial load would significantly increase the amplitude and range of slipping velocity, indicating that the skidding becomes more serious. As the ball still withstands contact load in the load-decreasing region, large slipping velocity would increase the temperature of both bearing and lubricant oil, intensify the wear and then might shorten the bearing service life. Therefore, the radial load should be considered carefully in the design and monitoring of rotating machinery.

  12. Stress evolution during caldera collapse

    Science.gov (United States)

    Holohan, E. P.; Schöpfer, M. P. J.; Walsh, J. J.

    2015-07-01

    The mechanics of caldera collapse are subject of long-running debate. Particular uncertainties concern how stresses around a magma reservoir relate to fracturing as the reservoir roof collapses, and how roof collapse in turn impacts upon the reservoir. We used two-dimensional Distinct Element Method models to characterise the evolution of stress around a depleting sub-surface magma body during gravity-driven collapse of its roof. These models illustrate how principal stress orientations rotate during progressive deformation so that roof fracturing transitions from initial reverse faulting to later normal faulting. They also reveal four end-member stress paths to fracture, each corresponding to a particular location within the roof. Analysis of these paths indicates that fractures associated with ultimate roof failure initiate in compression (i.e. as shear fractures). We also report on how mechanical and geometric conditions in the roof affect pre-failure unloading and post-failure reloading of the reservoir. In particular, the models show how residual friction within a failed roof could, without friction reduction mechanisms or fluid-derived counter-effects, inhibit a return to a lithostatically equilibrated pressure in the magma reservoir. Many of these findings should be transferable to other gravity-driven collapse processes, such as sinkhole formation, mine collapse and subsidence above hydrocarbon reservoirs.

  13. Random power series in the unit ball of Cn

    International Nuclear Information System (INIS)

    Shi Jihuai.

    1989-07-01

    The random power series in the unit disc has been studied by many authors. In this paper, we studied the random power series in the unit ball of C n and generalized some results in the unit disc to the unit ball, in particular, the result obtained recently by Duren has been generalized to the unit ball. The main tool used here is the generalized Salem-Zygmund's theorem. (author). 12 refs

  14. The spectral appearance of solar-type collapsing protostellar clouds

    International Nuclear Information System (INIS)

    Bertout, C.; Yorke, H.W.

    1978-04-01

    In this paper, we review the spectral properties of collapsing protostellar clouds, based on radiative transfer computations in hydrodynamic protostar models. In the first section, the basic results of protostar evolution computations in spherically symmetric and axially symmetry geometries, as they pertain to the appearance of protostars, are briefly reviewed. In the second section, we discuss the continuum appearance of spherically symmetric protostars with various masses. Also, we present recent results for the continuum appearance of an axially symmetric protostellar cloud. The third section deals with the line formation problem and describes preliminary results for a OH molecule in an axially symmetric collapsing cloud. Then we review recent theoretical and observational results obtained for the last evolutionary phase of protostars, known as the YY Orionis phase, when the stellar core first becomes visible in the optical range. Some of the new results and conclusions presented here can be summarized as follows: Rotating collapsing clouds are in general less luminous and cooler than corresponding non-rotating clouds - due to the longer evolutionary time scale. Nevertheless, high resolution studies (resolution [de

  15. Thermoelastoplastic Deformation of a Multilayer Ball

    Science.gov (United States)

    Murashkin, E. V.; Dats, E. P.

    2017-09-01

    The problem of centrally symmetric deformation of a multilayer elastoplastic ball in the process of successive accretion of preheated layers to its outer surface is considered in the framework of small elastoplastic deformations. The problems of residual stress formation in the elastoplastic ball with an inclusion and a cavity are solved under various mechanical boundary conditions on the inner surface and for prescribed thermal compression distributions. The graphs of residual stress and displacement fields are constructed.

  16. The collapse of the columnar spatial topology of pseudogap excitations in the underdoped-overdoped transition of cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Roehler, Juergen [Universitaet zu Koeln, 50937 Koeln (Germany)

    2016-07-01

    The intensity I{sub Q{sub 0}} of the Q=0 nematic pseudogap excitations in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} was found to increase between p ≥ 0.06 and 0.14 and to collapse at p{sub opt}=0.16, reaching zero at p=0.2. Evidentially it maps the growth and the collapse of the bulge in the doping dependence of the basal-plane area (ab) of p-type cuprates. The nematic topology of the pseudogap excitations results from the non-occupancy constraint for nn ZR-holes excluding 1a dimerization, but favoring 3a pair states with inequivalent O{sub x,y} sites. 3a pair states have hard core properties, yield d-type CDW excitations, and inflate the basal-plane area by a columnar topology against covalency-driven contraction. We show that optimal delocalization of ZR-holes at p{sub opt}=1/6 ≅ 0.17, tantamount to maximal connectedness of 3a pair states, will transform the columnar nematic pattern into isotropic tweedy striations, hence collapses I{sub Q{sub 0}}, and the bulge.

  17. Forecasting giant, catastrophic slope collapse: lessons from Vajont, Northern Italy

    Science.gov (United States)

    Kilburn, Christopher R. J.; Petley, David N.

    2003-08-01

    Rapid, giant landslides, or sturzstroms, are among the most powerful natural hazards on Earth. They have minimum volumes of ˜10 6-10 7 m 3 and, normally preceded by prolonged intervals of accelerating creep, are produced by catastrophic and deep-seated slope collapse (loads ˜1-10 MPa). Conventional analyses attribute rapid collapse to unusual mechanisms, such as the vaporization of ground water during sliding. Here, catastrophic collapse is related to self-accelerating rock fracture, common in crustal rocks at loads ˜1-10 MPa and readily catalysed by circulating fluids. Fracturing produces an abrupt drop in resisting stress. Measured stress drops in crustal rock account for minimum sturzstrom volumes and rapid collapse accelerations. Fracturing also provides a physical basis for quantitatively forecasting catastrophic slope failure.

  18. Nano-oxide nucleation in a 14Cr-ODS steel elaborated by reactive-inspired ball-milling: Multiscale characterizations

    International Nuclear Information System (INIS)

    Brocq, M.; Legendre, F.; Sakasegawa, H.; Radiguet, B.; Cuvilly, F.; Pareige, P.; Mathon, M.H.

    2009-01-01

    Oxide dispersion strengthened (ODS) steels are promising structural materials for both fusion and fission Generation IV reactors. Indeed, they exhibit excellent mechanical and creep properties and radiation resistance thanks to a fine and dense dispersion of complex nanometric oxides. ODS steels are usually elaborated by ball-milling iron based and yttrium oxide powders and then by thermomechanical treatments. It is expected that ball-milling dissolves yttrium oxides in the metallic matrix and that annealing induces nano-oxide precipitation. However the formation mechanism remains unclear and as a consequence the process is still uncontrolled. In this context, we proposed a new approach based on reactive ball milling of iron oxide (Fe 2 O 3 ), yttria (YFe 3 ) and iron based alloy in a dedicated instrumented ball-milling device. Also, a fine scale characterization, after each step of the process including ball-milling, is performed. A Fe-14Cr-2W-1Ti-0.8Y-0.2O (%wt) ODS steel was synthesized by reactive ball-milling and was characterized at very fine scale in both as-milled and as-annealed state. Atom Probe Tomography (APT) and Small Angle Neutron Scattering (SANS) were combined. After ballmilling, most of Y and O were, as expected, in solution in the ferritic matrix but some complex Y-Ti nano-oxides were also observed, indicating that oxide nucleation can start during ball-milling. With annealing the number of nano-oxides increases. In this presentation, experimental results of APT and SANS will be detailed and compared with what is usually observed in ODS steels elaborated by conventional ball milling. Finally, a formation mechanism of nano-oxides deduced from these results will be proposed. (author)

  19. Fire-induced collapses of steel structures

    DEFF Research Database (Denmark)

    Dondera, Alexandru; Giuliani, Luisa

    Single-story steel buildings such as car parks and industrial halls are often characterised by stiff beams and flexible columns and may experience an outward (sway) collapse during a fire, endangering people and properties outside the building. It is therefore a current interest of the research...... to investigate the collapse behaviour of single-story steel frames and identify relevant structural characteristics that influence the collapse mode. In this paper, a parametric study on the collapse a steel beam-column assembly with beam hinged connection and fixed column support is carried out under...... on the beam. By means of those tables, a simple method for the assessment and the countermeasure of unsafe collapse mode of single-story steel buildings can be derived....

  20. Granular Silo collapse: an experimental study

    Science.gov (United States)

    Clement, Eric; Gutierriez, Gustavo; Boltenhagen, Philippe; Lanuza, Jose

    2008-03-01

    We present an experimental work that develop some basic insight into the pre-buckling behavior and the buckling transition toward plastic collapse of a granular silo. We study different patterns of deformation generated on thin paper cylindrical shells during granular discharge. We study the collapse threshold for different bed height, flow rates and grain sizes. We compare the patterns that appear during the discharge of spherical beads, with those obtained in the axially compressed cylindrical shells. When the height of the granular column is close to the collapse threshold, we describe a ladder like pattern that rises around the cylinder surface in a spiral path of diamond shaped localizations, and develops into a plastic collapsing fold that grows around the collapsing silo.

  1. Validity and Reliability of a Medicine Ball Explosive Power Test.

    Science.gov (United States)

    Stockbrugger, Barry A.; Haennel, Robert G.

    2001-01-01

    Evaluated the validity and reliability of a medicine ball throw test to evaluate explosive power. Data on competitive sand volleyball players who performed a medicine ball throw and a standard countermovement jump indicated that the medicine ball throw test was a valid and reliable way to assess explosive power for an analogous total-body movement…

  2. De Novo Collapsing Glomerulopathy in a Renal Allograft Recipient

    Directory of Open Access Journals (Sweden)

    Kanodia K

    2008-01-01

    Full Text Available Collapsing glomerulopathy (CG, characterized histologically by segmental/global glomerular capillary collapse, podocyte hypertrophy and hypercellularity and tubulo-interstitial injury; is characterized clinically by massive proteinuria and rapid progressive renal failure. CG is known to recur in renal allograft and rarely de novo. We report de novo CG 3 years post-transplant in a patient who received renal allograft from haplo-identical type donor.

  3. Post-collapse perturbation theory in 1D cosmology - beyond shell-crossing

    Science.gov (United States)

    Taruya, Atsushi; Colombi, Stéphane

    2017-10-01

    We develop a new perturbation theory (PT) treatment that can describe gravitational dynamics of large-scale structure after shell-crossing in the one-dimensional cosmological case. Starting with cold initial conditions, the motion of matter distribution follows at early stages the single-stream regime, which can, in one dimension, be described exactly by the first-order Lagrangian perturbation, I.e. the Zel'dovich solution. However, the single-stream flow no longer holds after shell-crossing and a proper account of the multistream flow is essential for post-collapse dynamics. In this paper, extending previous work by Colombi, we present a perturbative description for the multistream flow after shell-crossing in a cosmological setup. In addition, we introduce an adaptive smoothing scheme to deal with the bulk properties of phase-space structures. The filtering scales in this scheme are linked to the next-crossing time in the post-collapse region, estimated from our PT calculations. Our PT treatment combined with adaptive smoothing is illustrated in several cases. Predictions are compared to simulations and we find that post-collapse PT with adaptive smoothing reproduces the power spectrum and phase-space structures remarkably well even at small scales, where Zel'dovich solution substantially deviates from simulations.

  4. Upper limits on gravitational-wave bursts radiated from stellar-core collapses in our galaxy

    International Nuclear Information System (INIS)

    Ando, Masaki; Akutsu, Tomomi; Akutsu, Tomotada

    2005-01-01

    We present the results of observations with the TAMA300 gravitational-wave detector, targeting burst signals from stellar-core collapse events. We used an excess-power filter to extract gravitational-wave candidates, and developed two methods to reduce fake events caused by non-stationary noises of the detector. These analysis methods were applied to real data from the TAMA300 interferometric gravitational wave detector. We compared the data-processed results with those of a Monte Carlo simulation with an assumed galactic-event distribution model and with burst waveforms expected from numerical simulations of stellar-core collapses, in order to interpret the event candidates from an astronomical viewpoint. We set an upper limit of 5.0 x 10 3 events s -1 on the burst gravitational-wave event rate in our galaxy with a confidence level of 90%

  5. Real-time detecting and tracking ball with OpenCV and Kinect

    Science.gov (United States)

    Osiecki, Tomasz; Jankowski, Stanislaw

    2016-09-01

    This paper presents a way to detect and track ball with using the OpenCV and Kinect. Object and people recognition, tracking are more and more popular topics nowadays. Described solution makes it possible to detect ball based on the range, which is set by the user and capture information about ball position in three dimensions. It can be store in the computer and use for example to display trajectory of the ball.

  6. Estructura temporal y gestual del kin-ball

    Directory of Open Access Journals (Sweden)

    Rafael Díaz Amate

    2015-06-01

    Full Text Available El objetivo de este estudio es analizar la estructura temporal del kin-ball y cuantificar el número de golpeos, jugadas, puntos y los tipos de contacto utilizados, en cada período y partido. Se han analizado un total de 13 partidos, correspondientes a la fase de grupos, semifinales y final del VII Campeonato de España de Kin-ball. Es un deporte caracterizado por la realización de esfuerzos interválicos de intensidad media-alta y de corta duración. Un partido de kin-ball tiene una duración media de 46 min aproximadamente, siendo el ratio tiempo de trabajo y tiempo de descanso de 1:1,51 y la duración media por punto de 12,07 s. Así, un partido de kin-ball tiene un volumen de 73 puntos con un total de 390 golpeos. Los tipos de golpeos utilizados determinan que es un deporte defensivo. Todos estos análisis ayudan a tener un mayor conocimiento de esta disciplina deportiva por parte de los entrenadores y jugadores para tener un entrenamiento más específico.

  7. Template-free synthesis of fully collapsed carbon nanotubes and graphene nanoribbons by chemical vapor deposition

    International Nuclear Information System (INIS)

    Zhang, Yong-Xing; Jia, Yong

    2015-01-01

    Highlights: • Commercial Fe 2 O 3 and Al 2 O 3 powders were chosen to prepare Fe 2 O 3 /Al 2 O 3 catalyst. • Fully collapsed carbon nanotubes and graphene nanoribbons were synthesized through the catalytic decomposition of methane at 900 °C. • The formation mechanism of the fully collapsed carbon nanotubes was revealed. - Abstract: Fe 2 O 3 /Al 2 O 3 catalyst was prepared by simply calcining the mixture of commercial Fe 2 O 3 and Al 2 O 3 powders at 1000 °C. The obtained Fe 2 O 3 /Al 2 O 3 catalyst shows high efficiency for the synthesis of fully collapsed carbon nanotubes and graphene nanoribbons through the catalytic decomposition of methane at 900 °C. The yield of the fully collapsed carbon nanotubes and graphene nanoribbons was 19.5 wt%. Field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and thermal gravimetric analysis were used to characterize the products. A tip-growth mechanism for the fully collapsed carbon nanotubes was suggested based on the SEM and TEM images of products produced at the initial stage. The break through of the catalyst particle from graphite layers resulted in the crack and then cut open of the fully collapsed carbon nanotubes, which further resulted in the formation of the graphene nanoribbons.

  8. Characterizing the collapse of a cavitation bubble cloud in a focused ultrasound field

    Science.gov (United States)

    Maeda, Kazuki; Colonius, Tim

    2017-11-01

    We study the coherent collapse of clouds of cavitation bubbles generated by the passage of a pulse of ultrasound. In order to characterize such collapse, we conduct a parametric study on the dynamics of a spherical bubble cloud with a radius of r = O(1) mm interacting with traveling ultrasound waves with an amplitude of pa = O(102 -106) Pa and a wavelength of λ = O(1 - 10) mm in water. Bubbles with a radius of O(10) um are treated as spherical, radially oscillating cavities dispersed in continuous liquid phase. The volume of Lagrangian point bubbles is mapped with a regularization kernel as void fraction onto Cartesian grids that defines the Eulerian liquid phase. The flow field is solved using a WENO-based compressible flow solver. We identified that coherent collapse occurs when λ >> r , regardless of the value of pa, while it only occurs for sufficiently high pa when λ r . For the long wavelength case, the results agree with the theory on linearized dynamics of d'Agostino and Brennen (1989). We extend the theory to short wave length case. Finally, we analyze the far-field acoustics scattered by individual bubbles and correlate them with the cloud collapse, for applications to acoustic imaging of bubble cloud dynamics. Funding supported by NIH P01-DK043881.

  9. Effect of ball milling time on thermoelectric properties of bismuth telluride nanomaterials

    Science.gov (United States)

    Khade, Poonam; Bagwaiya, Toshi; Bhattacharaya, Shovit; Singh, Ajay; Jha, Purushottam; Shelke, Vilas

    2018-04-01

    The effect of different milling time on thermoelectric properties of bismuth telluride (Bi2Te3) was investigated. The nanomaterial was prepared by varying the ball milling time and followed by hot press sintering. The crystal structure and phase formation were verified by X-ray diffraction and Raman Spectroscopy. The experimental results show that electrical conductivity increases whereas thermal conductivity decreases with increasing milling time. The negative sign of seebeck coefficient indicate the n-type nature with majority charge carriers of electrons. A maximum figure of merit about 0.55 is achieved for l5hr ball milled Bi2Te3 sample. The present study demonstrates the simple and cost-effective method for synthesis of Bi2Te3 thermoelectric material at large scale thermoelectric applications.

  10. Probabilistic Modeling of Landfill Subsidence Introduced by Buried Structure Collapse - 13229

    International Nuclear Information System (INIS)

    Foye, Kevin; Soong, Te-Yang

    2013-01-01

    The long-term reliability of land disposal facility final cover systems - and therefore the overall waste containment - depends on the distortions imposed on these systems by differential settlement/subsidence. The evaluation of differential settlement is challenging because of the heterogeneity of the waste mass and buried structure placement. Deterministic approaches to long-term final cover settlement prediction are not able to capture the spatial variability in the waste mass and sub-grade properties, especially discontinuous inclusions, which control differential settlement. An alternative is to use a probabilistic model to capture the non-uniform collapse of cover soils and buried structures and the subsequent effect of that collapse on the final cover system. Both techniques are applied to the problem of two side-by-side waste trenches with collapsible voids. The results show how this analytical technique can be used to connect a metric of final cover performance (inundation area) to the susceptibility of the sub-grade to collapse and the effective thickness of the cover soils. This approach allows designers to specify cover thickness, reinforcement, and slope to meet the demands imposed by the settlement of the underlying waste trenches. (authors)

  11. Influence of external magnetic field on the etching of a steel ball in an aqueous solution of nitric acid

    International Nuclear Information System (INIS)

    Yu, Ilchenko M.; Yu, Gorobets O.; Bondar, I.A.; Gaponov, A.M.

    2010-01-01

    The effect of change of shape of a steel ball was revealed as a result of its etching in an aqueous solution of nitric acid under influence of an external magnetic field. The elongation of a ferromagnetic ball was observed along the direction of an external magnetic field while etching took place uniformly in all the directions without magnetic field application. The steel ball etching in a magnetic field is characterized by formation of three cylindrically symmetric regions with different etching rates and surface structures, divided from each other by clear borders (namely, the pole, equator and transition regions are formed). The non-monotone dependences of etching rate, surface structure of a sample and sample shape after etching on an external magnetic field are observed.

  12. A novel animal model for hyperdynamic airway collapse.

    Science.gov (United States)

    Tsukada, Hisashi; O'Donnell, Carl R; Garland, Robert; Herth, Felix; Decamp, Malcolm; Ernst, Armin

    2010-12-01

    Tracheobronchomalacia (TBM) is increasingly recognized as a condition associated with significant pulmonary morbidity. However, treatment is invasive and complex, and because there is no appropriate animal model, novel diagnostic and treatment strategies are difficult to evaluate. We endeavored to develop a reliable airway model to simulate hyperdynamic airway collapse in humans. Seven 20-kg male sheep were enrolled in this study. Tracheomalacia was created by submucosal resection of > 50% of the circumference of 10 consecutive cervical tracheal cartilage rings through a midline cervical incision. A silicone stent was placed in the trachea to prevent airway collapse during recovery. Tracheal collapsibility was assessed at protocol-specific time points by bronchoscopy and multidetector CT imaging while temporarily removing the stent. Esophageal pressure and flow data were collected to assess flow limitation during spontaneous breathing. All animals tolerated the surgical procedure well and were stented without complications. One sheep died at 2 weeks because of respiratory failure related to stent migration. In all sheep, near-total forced inspiratory airway collapse was observed up to 3 months postprocedure. Esophageal manometry demonstrated flow limitation associated with large negative pleural pressure swings during rapid spontaneous inhalation. Hyperdynamic airway collapse can reliably be induced with this technique. It may serve as a model for evaluation of novel diagnostic and therapeutic strategies for TBM.

  13. Long-Term Effects on Graphene Supercapacitors of Using a Zirconia Bowl and Zirconia Balls for Ball-Mill mixing of Active Materials

    Science.gov (United States)

    Song, Dae-Hoon; Kim, Jin-Young; Kahng, Yung Ho; Cho, Hoonsung; Kim, Eung-Sam

    2018-04-01

    Improving the energy storage performance of supercapacitor electrodes based on reduced graphene oxide (RGO) is one of the main subjects in this research field. However, when a zirconia bowl and zirconia balls were used for ball-mill mixing of the active materials for RGO supercapacitors, the energy storage performance deteriorated over time. Our study revealed that the source of the problem was the inclusion of zirconia bits from abrasion of the bowl and the balls during the ballmill mixing, which increased during a period of 1 year. We probed two solutions to this problem: 1) hydrofluoric (HF) acid treatment of the RGO supercapacitors and 2) use of a tempered steel bowl and tempered steel balls for the mixing. For both cases, the energy storage performance was restored to near the initial level, showing a specific capacitance ( C sp ) of 200 F/g. Our results should lead to progress in research on RGO supercapacitors.

  14. Unifying Research on Social-Ecological Resilience and Collapse.

    Science.gov (United States)

    Cumming, Graeme S; Peterson, Garry D

    2017-09-01

    Ecosystems influence human societies, leading people to manage ecosystems for human benefit. Poor environmental management can lead to reduced ecological resilience and social-ecological collapse. We review research on resilience and collapse across different systems and propose a unifying social-ecological framework based on (i) a clear definition of system identity; (ii) the use of quantitative thresholds to define collapse; (iii) relating collapse processes to system structure; and (iv) explicit comparison of alternative hypotheses and models of collapse. Analysis of 17 representative cases identified 14 mechanisms, in five classes, that explain social-ecological collapse. System structure influences the kind of collapse a system may experience. Mechanistic theories of collapse that unite structure and process can make fundamental contributions to solving global environmental problems. Copyright © 2017. Published by Elsevier Ltd.

  15. Ambipolar diffusion regulated collapse of filaments threaded by perpendicular magnetic fields

    Science.gov (United States)

    Burge, C. A.; Van Loo, S.; Falle, S. A. E. G.; Hartquist, T. W.

    2016-11-01

    Context. In giant molecular clouds (GMCs), the fractional ionisation is low enough that the neutral and charged particles are weakly coupled. A consequence of this is that the magnetic flux redistributes within the cloud, allowing an initially magnetically supported region to collapse. Aims: We aim to elucidate the effects of ambipolar diffusion on the evolution of infinitely long filaments and the effect of decaying turbulence on that evolution. Methods: First, in ideal magnetohydrodynamics (MHD), a two-dimensional cylinder of an isothermal magnetised plasma with initially uniform density was allowed to evolve to an equilibrium state. Then, the response of the filament to ambipolar diffusion was followed using an adaptive mesh refinement multifluid MHD code. Various ambipolar resistivities were chosen to reflect different ratios of Jeans length to ambipolar diffusion length scale. To study the effect of turbulence on the ambipolar diffusion rate, we perturbed the equilibrium filament with a turbulent velocity field quantified by a rms sonic Mach number, Mrms, of 10, 3 or 1. Results: We numerically reproduce the density profiles for filaments that are in magnetohydrostatic and pressure equilibrium with their surroundings obtained in a published model and show that these equilibria are dynamically stable. If the effect of ambipolar diffusion is considered, these filaments lose magnetic support initiating cloud collapse. The filaments do not lose magnetic flux. Rather the magnetic flux is redistributed within the filament from the dense centre towards the diffuse envelope. The rate of the collapse is inversely proportional to the fractional ionisation and two gravitationally-driven ambipolar diffusion regimes for the collapse are observed as predicted in a published model. For high values of the ionisation coefficient, that is X ≥ 10-7, the gas is strongly coupled to the magnetic field and the Jeans length is larger than the ambipolar diffusion length scale. Then

  16. Pressure and tension waves from bubble collapse near a solid boundary: A numerical approach.

    Science.gov (United States)

    Lechner, Christiane; Koch, Max; Lauterborn, Werner; Mettin, Robert

    2017-12-01

    The acoustic waves being generated during the motion of a bubble in water near a solid boundary are calculated numerically. The open source package OpenFOAM is used for solving the Navier-Stokes equation and extended to include nonlinear acoustic wave effects via the Tait equation for water. A bubble model with a small amount of gas is chosen, the gas obeying an adiabatic law. A bubble starting from a small size with high internal pressure near a flat, solid boundary is studied. The sequence of events from bubble growth via axial microjet formation, jet impact, annular nanojet formation, torus-bubble collapse, and bubble rebound to second collapse is described. The different pressure and tension waves with their propagation properties are demonstrated.

  17. The Tool Life of Ball Nose end Mill Depending on the Different Types of Ramping

    Science.gov (United States)

    Vopát, Tomáš; Peterka, Jozef; Kováč, Martin

    2014-12-01

    The article deals with the cutting tool wear measurement process and tool life of ball nose end mill depending on upward ramping and downward ramping. The aim was to determine and compare the wear (tool life) of ball nose end mill for different types of copy milling operations, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. For tool life test, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, cutting speed, feed rate, axial depth of cut and radial depth of cut were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different tool life of ball nose end mills depending on the copy milling strategy.

  18. Collapse settlement in compacted soils

    CSIR Research Space (South Africa)

    Booth, AR

    1977-01-01

    Full Text Available Research into collapse settlement in compacted soils is described, with special reference to recent cases in Southern Africa where collapse settlement occurred in road embankments following wetting of the soil. The laboratory work described...

  19. Two-phase, reciprocal, double trapdoor collapse at Hannegan caldera, North Cascades, Washington, USA

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, David S [Mount Baker Volcano Research Center Geology Department Western Washington University 516 High Street Bellingham, Washington 98225-9080 (United States)], E-mail: DaveTucker@mbvo.wwu.edu

    2008-10-01

    The intracaldera Hannegan volcanics were erupted during two collapse episodes of the Hannegan caldera in the North Cascade mountains of Washington State. The first eruption yielded a down-to-the-north trapdoor style collapse at 3.722 {+-} 0.020 Ma (40Ar/39Ar) that is bounded by a horseshoe-shaped ring fault. The second collapse, most probably also trapdoor style, followed a short period of sedimentation, and completed the elliptical ring fault around the southern margin of the caldera. Post caldera plutons, with U-Pb ages of 3.42 {+-} 0.10 and 3.36 {+-} 0.20 Ma, intruded the intracaldera ignimbrite.

  20. Wear numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in

  1. Standard Test Method for Determining Resistance of Photovoltaic Modules to Hail by Impact with Propelled Ice Balls

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method provides a procedure for determining the ability of photovoltaic modules to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. 1.2 This test method defines test specimens and methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, provides a method for determining changes in electrical performance, and specifies parameters that must be recorded and reported. 1.3 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice ball impact resistance is beyond the scope of this test method. 1.4 The size of the ice ball to be used in conducting this test is not specified. This test method can be used with various sizes of ice balls. 1.5 This test method may be applied to concentrator and nonconcentrator modules. 1.6 The v...

  2. Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1992-01-01

    1.1 This practice covers a procedure for determining the ability of cover plates for flat-plate solar collectors to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. This practice is not intended to apply to photovoltaic cells or arrays. 1.2 This practice defines two types of test specimens, describes methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, and specifies parameters that must be recorded and reported. 1.3 This practice does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice-ball impact resistance is beyond the scope of this practice. 1.4 The size of ice ball to be used in conducting this test is not specified in this practice. This practice can be used with various sizes of ice balls. 1.5 The categories of solar collector cover plat...

  3. Two balls and a string: from ordered motion to chaos

    International Nuclear Information System (INIS)

    Sacks, William; Mauger, Alain

    2013-01-01

    Two spherical balls are connected by a taught string passing through a small hole in a perfectly planar table: the first ball, subject to a central force, moves without friction on a two-dimensional plane, while the second ball moves only along the vertical axis directly below the hole. The pedagogical aspects of this novel two-body problem are given particular attention: Newton’s laws, central force motion, conservation laws, angular momentum, constraints, etc. The dynamics of the system is considered under various initial conditions wherein the ball on the table moves qualitatively in rotating ellipses or hypotrochoids. The conditions for closed or periodic orbits are examined. The more complex case of the inclined plane is then considered, revealing a rich variety of periodic, aperiodic and chaotic solutions as a function of the ball mass ratio and the plane inclination angle. The associated Poincaré phase-space maps are discussed. (paper)

  4. Spherically symmetric scalar field collapse

    Indian Academy of Sciences (India)

    2013-03-01

    Mar 1, 2013 ... The very recent interest in scalar field collapse stems from a cosmological ... The objective of the present investigation is to explore the collapsing modes of a simple ..... The authors thank the BRNS (DAE) for financial support.

  5. Behavior of hollow balls containing granules bouncing repeatedly off the ground

    Science.gov (United States)

    Hu, Min; Mu, Qing-song; Luo, Ning; Li, Gang; Peng, Ning-bo

    2013-07-01

    An experimental study of the behavior of hollow balls filled with some granules (mung beans or millets) bouncing repeatedly off a static flat horizontal surface is presented. We observed that the bounce number of the ball is limited and decreases regularly with an increasing number of granules. Moreover, for two balls containing a different kind of granules, their bounce numbers are basically equal when the two balls have the same mass of granules. While there is no clear relationship between the first rebound height of one ball and the number of granules, there appears an exponential decay of the second rebound height with an increase of the granule number. Furthermore, a two-dimensional numerical model has been created to find out the law of the ball's rebound height and the dissipation law of the granule nested system. A generalized prediction equation to reasonably explain the law of the bounce number has also been proposed.

  6. Forensic Fluid Dynamics and the Indian Spring (1991) cave collapse problem

    Science.gov (United States)

    Nof, D.

    2013-05-01

    The collapse of the Indian spring cave (Florida) in 1991 was unique because it occurred while cave divers were in the cave. For the most part, the submerged cave is large enough to accommodate a passing truck so the cave divers were not in touch with its walls and it is hard to imagine why would it naturally collapse just when the divers were in it. Recently, Nof and Paldor (2010) resolved this apparent paradox by suggesting that resonance in the air pockets in the cavern, created by breathing (open circuit) divers, may have contributed to the collapse. In this scenario, divers present in the cavern during the dive may have (unknowingly) caused the collapse through the pressurized air/gas that they release with each breath. When the breathing period of the diver(s) matches the natural oscillations period of the "cave oscillator", the ensuing resonance causes the air pressure in the pockets to increase uncontrollably. Here, we place the above theory on a more solid ground. To do so, we first extended the resonance theory from our original two-pockets, symmetrical U-tube model (with two identical branches that were not specifically identified within the cave system) to a one (identified) pocket in the cavern and a very broad basin (identified, of course) that serves as the other branch of the U-tube. Our methodology is to apply familiar fluid dynamics principles to the situation that occurred in the cave. We did so, step-by-step, on the basis of our interviews with four out of the five surviving cave-divers. Namely, we dissected their testimonies to arrive at a physically plausible scenario determined on basis of a fluid dynamics application to the natural flow in the cave and the flow induced by the compressed air released by the divers as well as the collapsed mud. We found that the oscillation period was larger than what we earlier calculated (still relevant to the case, nevertheless), and that, in contrast to what most cave divers believe, there was a temporary

  7. Dry grinding of talc in a stirred ball mill

    Directory of Open Access Journals (Sweden)

    Cayirli Serkan

    2016-01-01

    Full Text Available The aim of this work was to investigate micro fine size dry grindability of talc in a stirred ball mill. The effects of various parameters such as grinding time, stirrer speed, powder filling ratio and ball filling ratio were investigated. Alumina balls were used as grinding media. Experiments were carried out using the 24 full factorial design. The main and interaction effects were evaluated using the Yates method. Test results were evaluated on the basis of product size and surface area.

  8. Ball-milling-induced crystallization and ball-milling effect on thermal crystallization kinetics in an amorphous FeMoSiB alloy

    International Nuclear Information System (INIS)

    Guo, F.Q.; Lu, K.

    1997-01-01

    Microstructure evolution in a melt-spun amorphous Fe 77.2 Mo 0.8 Si 9 B 13 alloy subjected to high-energy ball milling was investigated by means of X-ray diffraction (XRD), a transmission electron microscope (TEM), and a differential scanning calorimeter (DSC). It was found that during ball milling, crystallization occurs in the amorphous ribbon sample with precipitation of an α-Fe solid solution, and the amorphous sample crystallizes completely into a single α-Fe nanostructure (rather than α-Fe and borides as in the usual thermal crystallization products) when the milling time exceeds 135 hours. The volume fraction of material crystallized was found to be approximately proportional to the milling time. The fully crystallized sample with a single α-Fe nanophase exhibits an intrinsic thermal stability against phase separation upon annealing at high temperatures. The ball-milling effect on the subsequent thermal crystallization of the amorphous phase in an as-milled sample was studied by comparison of the crystallization products and kinetic parameters between the as-quenched amorphous sample and the as-milled sample was studied by comparison of the crystallization products and kinetic parameters between the as-quenched amorphous sample and the as-milled partially crystallized samples. The crystallization temperatures and activation energies for the crystallization processes of the residual amorphous phase were considerably decreased due to ball milling, indicating that ball milling has a significant effect on the depression of thermal stability of the residual amorphous phase

  9. Progressive Collapse of High-Rise Buildings from Fire

    Directory of Open Access Journals (Sweden)

    Pershakov Valerii

    2016-01-01

    Full Text Available Considers ensuring the stability of structures of high-rise buildings against progressive collapse due to fire, proposed measures to ensure the stability of high-rise buildings due to progressive collapse. The analysis of large fires in high-rise buildings with progressive collapse and review of the literature on the issue of progressive collapse. The analysis of the Ukrainian normative documents on progressive collapse resistance.

  10. a Uav Based 3-D Positioning Framework for Detecting Locations of Buried Persons in Collapsed Disaster Area

    Science.gov (United States)

    Moon, H.; Kim, C.; Lee, W.

    2016-06-01

    Regarding spatial location positioning, indoor location positioning theories based on wireless communication techniques such as Wi-Fi, beacon, UWB and Bluetooth has widely been developing across the world. These techniques are mainly focusing on spatial location detection of customers using fixed wireless APs and unique Tags in the indoor environment. Besides, since existing detection equipment and techniques using ultrasound or sound etc. to detect buried persons and identify survival status for them cause 2nd damages on the collapsed debris for rescuers. In addition, it might take time to check the buried persons. However, the collapsed disaster sites should consider both outdoor and indoor environments because empty spaces under collapsed debris exists. In order to detect buried persons from the empty spaces, we should collect wireless signals with Wi-Fi from their mobile phone. Basically, the Wi-Fi signal measure 2-D location. However, since the buried persons have Z value with burial depth, we also should collect barometer sensor data from their mobile phones in order to measure Z values according to weather conditions. Specially, for quick accessibility to the disaster area, a drone (UAV; Unmanned Arial Vehicle) system, which is equipped with a wireless detection module, was introduced. Using these framework, this study aims to provide the rescuers with effective rescue information by calculating 3-D location for buried persons based on the wireless and barometer sensor fusion.

  11. Towards asteroseismology of core-collapse supernovae with gravitational-wave observations - I. Cowling approximation

    Science.gov (United States)

    Torres-Forné, Alejandro; Cerdá-Durán, Pablo; Passamonti, Andrea; Font, José A.

    2018-03-01

    Gravitational waves from core-collapse supernovae are produced by the excitation of different oscillation modes in the protoneutron star (PNS) and its surroundings, including the shock. In this work we study the relationship between the post-bounce oscillation spectrum of the PNS-shock system and the characteristic frequencies observed in gravitational-wave signals from core-collapse simulations. This is a fundamental first step in order to develop a procedure to infer astrophysical parameters of the PNS formed in core-collapse supernovae. Our method combines information from the oscillation spectrum of the PNS, obtained through linear perturbation analysis in general relativity of a background physical system, with information from the gravitational-wave spectrum of the corresponding non-linear, core-collapse simulation. Using results from the simulation of the collapse of a 35 M⊙ pre-supernova progenitor we show that both types of spectra are indeed related and we are able to identify the modes of oscillation of the PNS, namely g-modes, p-modes, hybrid modes, and standing accretion shock instability (SASI) modes, obtaining a remarkably close correspondence with the time-frequency distribution of the gravitational-wave modes. The analysis presented in this paper provides a proof of concept that asteroseismology is indeed possible in the core-collapse scenario, and it may serve as a basis for future work on PNS parameter inference based on gravitational-wave observations.

  12. Template-free synthesis of fully collapsed carbon nanotubes and graphene nanoribbons by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong-Xing [School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Jia, Yong, E-mail: yjiaahedu@163.com [School of Pharmacy, Anhui University of Chinese Medicine, Hefei 230012 (China)

    2015-12-01

    Highlights: • Commercial Fe{sub 2}O{sub 3} and Al{sub 2}O{sub 3} powders were chosen to prepare Fe{sub 2}O{sub 3}/Al{sub 2}O{sub 3} catalyst. • Fully collapsed carbon nanotubes and graphene nanoribbons were synthesized through the catalytic decomposition of methane at 900 °C. • The formation mechanism of the fully collapsed carbon nanotubes was revealed. - Abstract: Fe{sub 2}O{sub 3}/Al{sub 2}O{sub 3} catalyst was prepared by simply calcining the mixture of commercial Fe{sub 2}O{sub 3} and Al{sub 2}O{sub 3} powders at 1000 °C. The obtained Fe{sub 2}O{sub 3}/Al{sub 2}O{sub 3} catalyst shows high efficiency for the synthesis of fully collapsed carbon nanotubes and graphene nanoribbons through the catalytic decomposition of methane at 900 °C. The yield of the fully collapsed carbon nanotubes and graphene nanoribbons was 19.5 wt%. Field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and thermal gravimetric analysis were used to characterize the products. A tip-growth mechanism for the fully collapsed carbon nanotubes was suggested based on the SEM and TEM images of products produced at the initial stage. The break through of the catalyst particle from graphite layers resulted in the crack and then cut open of the fully collapsed carbon nanotubes, which further resulted in the formation of the graphene nanoribbons.

  13. Determination of the boundary conditions of the grinding load in ball mills

    Science.gov (United States)

    Sharapov, Rashid R.

    2018-02-01

    The prospects of application in ball mills for grinding cement clinker with inclined partitions are shown. It is noted that ball mills with inclined partitions are more effective. An algorithm is proposed for calculating the power consumed by a ball mill with inclined inter-chamber partitions in which an axial movement of the ball load takes place. The boundary conditions in which the ball load is located are determined. The equations of bounding the grinding load are determined. The behavior of a grinding load is considered in view of the characteristic cross sections. The coordinates of the centers of gravity of the grinding load with a definite step and the shape of the cross sections are determined. It is theoretically shown that grinding load in some parts of the ball mill not only consumes, but also helps to rotate the ball mill. Methods for calculating complex analytical expressions for determining the coordinates of the centers of gravity of the grinding load under the conditions of its longitudinal motion have developed. The carried out researches allow to approach from the general positions to research of behavior of a grinding load in the ball mills equipped with various in-mill devices.

  14. Historiografia del “Ball de Torrent”: De la moixiganga barroca al quadre de balls populars valencians (1692-1929

    Directory of Open Access Journals (Sweden)

    Raül Sanchis Francés

    2013-06-01

    Full Text Available Resum: El Ball de Torrent és una moixiganga dramàtica popular escenificada a la ciutat de València i altres indrets del País Valencià des de finals del segle XVII fins a principis del segle XX. Estava organitzada per agrupacions gremials, juntes d’hospitals o clavaris de festes i protagonitzada per personatges agrupats en comparses que representaven una paròdia sobre les relacions entre les estructures de poder i les classes populars. Tot i la variabilitat segons el moment històric, es conforma com una mescla de quadres amb danses, música i jocs teatrals. El ball interacciona de diverses formes amb algunes festes valencianes i és, probablement, una de les mostres de teatre de carrer més nostrades i menys estudiades de la València Moderna. En aquest article es realitza una revisió bibliogràfica crítica i una primera anàlisi historiogràfica.Paraules clau: Ball de Torrent, Dansa i música tradicional, Teatre, Moixiganga, Festa valencianaAbstract: Ball de Torrent (Dance of Torrent is a popular dramatic masquerade staged in Valencia since the late seventeenth century to the early twentieth. It was organized by guilds, hospital managements or festival organizers. The actors were grouped in associations representing a parody on the relationships between power structures and popular classes. Despite the variability depending on the historical period, it consisted of a mixture of episodes or scenes with dance, music and theatre games. Any Festivals in Valencia are connected with the Ball de Torrent. It’s probably one of the most interesting samples of street theatre and studied under of the Modern Valencia. This paper analyses historical sources to review and critique bibliography.Keywords: Dance of Torrent, Traditional Dance and Music, Theatre, Masquerade, Feasts of Valencia

  15. Thermal Analysis of Ball screw Systems by Explicit Finite Difference Method

    Energy Technology Data Exchange (ETDEWEB)

    Min, Bog Ki [Hanyang Univ., Seoul (Korea, Republic of); Park, Chun Hong; Chung, Sung Chong [KIMM, Daejeon (Korea, Republic of)

    2016-01-15

    Friction generated from balls and grooves incurs temperature rise in the ball screw system. Thermal deformation due to the heat degrades positioning accuracy of the feed drive system. To compensate for the thermal error, accurate prediction of the temperature distribution is required first. In this paper, to predict the temperature distribution according to the rotational speed, solid and hollow cylinders are applied for analysis of the ball screw shaft and nut, respectively. Boundary conditions such as the convective heat transfer coefficient, friction torque, and thermal contact conductance (TCC) between balls and grooves are formulated according to operating and fabrication conditions of the ball screw. Explicit FDM (finite difference method) is studied for development of a temperature prediction simulator. Its effectiveness is verified through numerical analysis.

  16. Physical abrasion method using submerged spike balls to remove algal biofilm from photobioreactors.

    Science.gov (United States)

    Nawar, Azra; Khoja, Asif Hussain; Akbar, Naveed; Ansari, Abeera Ayaz; Qayyum, Muneeb; Ali, Ehsan

    2017-12-02

    A major factor in practical application of photobioreactors (PBR) is the adhesion of algal cells onto their inner walls. Optimized algal growth requires an adequate sunlight for the photosynthesis and cell growth. Limitation in light exposure adversely affects the algal biomass yield. The removal of the biofilm from PBR is a challenging and expansive task. This study was designed to develop an inexpensive technique to prevent adhesion of algal biofilm on tubular PBR to ensure high efficiency of light utilization. Rubber balls with surface projections were introduced into the reactor, to remove the adherent biofilm by physical abrasion technique. The floatation of spike balls created a turbulent flow, thereby inhibiting further biofilm formation. The parameters such as, specific growth rate and doubling time of the algae before introducing the balls were 0.451 day -1 and 1.5 days respectively. Visible biofilm impeding light transmission was formed by 15-20 days. The removal of the biofilm commenced immediately after the introduction of the spike balls with visibly reduced deposits in 3 days. This was also validated by enhance cell count (6.95 × 106 cells mL -1 ) in the medium. The employment of spike balls in PBR is an environmental friendly and economical method for the removal of biofilm.

  17. Gravitational collapse with rotating thin shells and cosmic censorship

    International Nuclear Information System (INIS)

    Delsate, Térence; Rocha, Jorge V; Santarelli, Raphael

    2015-01-01

    The study of gravitational collapse is a subject of great importance, both from an astrophysical and a holographic point of view. In this respect, exact solutions can be very helpful but known solutions are very scarce, especially when considering dynamical processes with rotation. We describe a setup in which gravitational collapse of rotating matter shells can be addressed with analytic tools, at the expense of going to higher dimensions and considering equal angular momenta spacetimes. The framework for an exact treatment of the dynamics, relying on a thin shell approximation, is developed. Our analysis allows the inclusion of a non-vanishing cosmological constant. Finally, we discuss applications of this machinery to the construction of stationary solutions describing matter around rotating black holes and to the cosmic censorship conjecture. (paper)

  18. The goalkeeper influence on ball possession effectiveness in futsal

    Directory of Open Access Journals (Sweden)

    Vicente-Vila Pedro

    2016-06-01

    Full Text Available The aim of this study was to identify which variables were the best predictors of success in futsal ball possession when controlling for space and task related indicators, situational variables and the participation of the goalkeeper as a regular field player or not (5 vs. 4 or 4 vs. 4. The sample consisted of 326 situations of ball possession corresponding to 31 matches played by a team from the Spanish Futsal League during the 2010–2011, 2011–2012 and 2012–2013 seasons. Multidimensional qualitative data obtained from 10 ordered categorical variables were used. Data were analysed using chi-square analysis and multiple logistic regression analysis. Overall, the highest ball possession effectiveness was achieved when the goalkeeper participated as a regular field player (p<0.01, the duration of the ball possession was less than 10 s (p<0.01, the ball possession ended in the penalty area (p<0.01 and the defensive pressure was low (p<0.01. The information obtained on the relative effectiveness of offensive playing tactics can be used to improve team’s goal-scoring and goal preventing abilities.

  19. An investigation of the generation and properties of laboratory-produced ball lightning

    Science.gov (United States)

    Oreshko, A. G.

    2015-06-01

    The experiments revealed that ball lightning is a self-confining quasi-neutral in a whole plasma system that rotates around its axis. Ball lightning has a structure of a spherical electric domain, consisting of a kernel with excess negative charge and an external spherical layer with excess positive charge. The excess of charges of one sort and the lack of charges of the other sort in the kernel or in the external spherical layer significantly reduces the possibility of electron capture by means of an electric field, created by the nearest ions and leads to a drastic slowdown of recombination process. Direct proof has been obtained that inside of ball lightning - in an external spherical layer that rotates around the axis - there is a circular current of sub-relativistic particles. This current creates and maintains its own poloidal magnetic field of ball lightning, i.e. it carries out the function of magnetic dynamo. The kernel of ball lightning is situated in a region with minimum values of induction of the magnetic field. The inequality of positive and negative charges in elements of ball lightning also significantly reduces losses of the charged plasma on bremsstrahlung. Ball lightning generation occurs in a plasmic vortex. The ball lightning energy in the region of its generation significantly differs from the ball lightning energy, which is drifting in space. The axial component of kinetic energy of particles slightly exceeds 100 keV and the rotational component of the ions energy is a bit greater than 1 MeV. Ball lightning is `embedded' in atmosphere autonomous accelerator of charged particles of a cyclotron type due to self-generation of strong crossed electric and magnetic fields. A discussion of the conditions of stability and long-term existence of ball lightning is given.

  20. An aerodynamic analysis of recent FIFA world cup balls

    Science.gov (United States)

    Kiratidis, Adrian L.; Leinweber, Derek B.

    2018-05-01

    Drag and lift coefficients of recent FIFA world cup balls are examined. We fit a novel functional form to drag coefficient curves and in the absence of empirical data provide estimates of lift coefficient behaviour via a consideration of the physics of the boundary layer. Differences in both these coefficients for recent balls, which result from surface texture modification, can significantly alter trajectories. Numerical simulations are used to quantify the effect these changes have on the flight paths of various balls. Altitude and temperature variations at recent world cup events are also discussed. We conclude by quantifying the influence these variations have on the three most recent world cup balls, the Brazuca, the Jabulani and the Teamgeist. While our paper presents findings of interest to the professional sports scientist, it remains accessible to students at the undergraduate level.

  1. Correlation of gas sensitivite properties with microstructure of Fe2O3-SnO2 ceramics prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lu, S.W.; Zhou, Y.X.

    1997-01-01

    A remarkable gas sensitivity to ethnaol gas has been observed in nanostructured Fe2O3-SnO2 materials with a composition of 6.4 mol% SnO2 prepared by high energy ball milling. The microstructure of the materials has been examined by x-ray diffraction (XRD) and Mossbauer spectroscopy. It was found...

  2. Lower bounds of collapse loads in axisymmetrical vessels

    International Nuclear Information System (INIS)

    Fonseca Neto, J. de D.; Ebecken, N.F.F.

    1981-01-01

    The rigid-plastic limit analysis of shells of revolution subject to rotationally symmetric loadings, is presented. After assembling the finite elements, the limit analysis program is reduced to a simple application of the non-linear programming technique, where the sequential unconstrained minimization technique (SUMT) is utilized for the statically admissible approach. Lower bounds of the collapse loads are presented and compared with the results described in the literature. (Author) [pt

  3. Possible precursors of ball lightning. Observation of closed loops in high voltage discharges

    International Nuclear Information System (INIS)

    Alexeff, I.; Rader, M.

    1995-01-01

    Several hundred photographs of ultrahigh voltage discharges have been obtained that show closed current loops. These closed current loops may be precursors of ball lightning. One feature of these discharges may explain why observations of ball lightning may be infrequent; that is, there is a distinct threshold in voltage and/or current below which the closed loops do not occur. This threshold current fits other experimental data but is well above the usually observed currents in natural lightning. 10 refs., 3 figs

  4. Results from the crystal ball detector at SPEAR

    International Nuclear Information System (INIS)

    Bloom, E.D.

    1979-11-01

    The Crystal Ball detector is a device particularly suited to the measurement of photons with energies lower than 1 GeV. The detector has as its principal component a 16 radiation length thick, highly segmented shell of NaI(Tl) surrounding cylindrical, proportional, and magnetostrictive spark chambers. The main Ball and various elements of the central chambers cover 94% of 4π sr. Segmented endcap NaI(Tl) detectors of 20 radiation lengths behind magneto strictive spark chambers supplement the main Ball. The Ball and endcaps close the solid angle for charged particle and photon detection to 98% of 4π sr. In addition, detectors of interspersed iron and proportional tubes provide for μ-π separation over 15% of 4π sr, about theta/sub CM/ = 90 0 . In this report preliminary results are presented from the data obtained. In particular, QED at E/sub CM/ = 6.5 GeV, R/sub hadron/ and related inclusive distributions, eta branching fractions at J/psi and psi'', and a detailed study of the psionium system are discussed

  5. The Tool Life of Ball Nose end Mill Depending on the Different Types of Ramping

    Directory of Open Access Journals (Sweden)

    Vopát Tomáš

    2014-12-01

    Full Text Available The article deals with the cutting tool wear measurement process and tool life of ball nose end mill depending on upward ramping and downward ramping. The aim was to determine and compare the wear (tool life of ball nose end mill for different types of copy milling operations, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. For tool life test, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, cutting speed, feed rate, axial depth of cut and radial depth of cut were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different tool life of ball nose end mills depending on the copy milling strategy.

  6. Measurements of the Motion of Plasma Filaments in a Plasma Ball

    International Nuclear Information System (INIS)

    Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S.J.

    2010-01-01

    Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ∼106 cm/sec at the driving frequency of ∼26 kHz, and drift upward through the ball at ∼1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

  7. Measurements of the Motion of Plasma Filaments in a Plasma Ball

    Energy Technology Data Exchange (ETDEWEB)

    Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S. J.

    2010-01-26

    Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ~106 cm/sec at the driving frequency of ~26 kHz, and drift upward through the ball at ~1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

  8. Results on charmonium from the Crystal Ball

    CERN Document Server

    Partridge, R; Bloom, Elliott D; Bulos, F; Burnett, T; Cavalli-Sforza, M; Chestnut, R; Coyne, D; Gaiser, J; Godfrey, G; Hofstadter, R; Kiesling, C; Kirkbride, I; Kolanoski, H; Kollmann, W; Liberman, A; O'Reilly, J; Oreglia, M J; Peck, C; Porter, F; Richardson, M; Sadrozinski, H F W; Strauch, K; Tompkins, J; Wacker, K

    1979-01-01

    Results from the Crystal Ball experiment at SPEAR are presented. A preliminary analysis of the 3 photon final state from the J/ psi (3095) and of the cascade decays of the psi '(3684) yield new upper limits on the controversial states X(2820), chi (3455) and the even C- parity state at 3.59 GeV. From inclusive gamma -ray spectra of the J/ psi and psi ' preliminary branching ratios for psi ' to chi states and upper limits for J/ psi , psi ' to eta /sub c/, eta /sub c/' are given. (15 refs).

  9. Structure Design and Performance Analysis of High-Speed Miniature Ball Bearing

    Science.gov (United States)

    Li, Songsheng; Zhang, Guoye; Chen, Bin; Shen, Yuan

    2017-07-01

    The working performances of miniature ball bearings are obviously affected by its’ geometric structure parameters. In this paper, quasi-static analysis theory is applied in the design of miniature ball bearings. Firstly, it is studied the influence of geometry structure, preload and rotating speed on the dynamic performance of bearing. Secondly, bearing dynamic characteristics are analyzed which include the bearing stiffness and Spin to roll Ratio. Lastly, the contact stress and bearing life are calculated. The results indicate that structure parameters play an importance role in bearing’s dynamic performances. Miniature ball bearings which have lager ball number, bigger ball diameter and smaller inner race groove radius can get better performances while velocity and preload have great impact on the bearing life. So that parameters of miniature bearing should be chosen cautiously.

  10. Innovative Laundering and Sanitization System to Extend Duration of Crew Clothing Wear, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation will refresh crew clothing to extend the duration of wear. It is a collapsible or portable light-weight cleaning sanitizing and deodorizing...

  11. Black hole formation in perfect fluid collapse

    International Nuclear Information System (INIS)

    Goswami, Rituparno; Joshi, Pankaj S

    2004-01-01

    We construct here a special class of perfect fluid collapse models which generalizes the homogeneous dust collapse solution in order to include nonzero pressures and inhomogeneities into evolution. It is shown that a black hole is necessarily generated as the end product of continued gravitational collapse, rather than a naked singularity. We examine the nature of the central singularity forming as a result of endless collapse and it is shown that no nonspacelike trajectories can escape from the central singularity. Our results provide some insights into how the dynamical collapse works and into the possible formulations of the cosmic censorship hypothesis, which is as yet a major unsolved problem in black hole physics

  12. Ball lightning dynamics and stability at moderate ion densities

    International Nuclear Information System (INIS)

    Morrow, R

    2017-01-01

    A general mechanism is presented for the dynamics and structure of ball lightning and for the maintenance of the ball lightning structure for several seconds. Results are obtained using a spherical geometry for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions and negative ions coupled with Poisson’s equation. A lightning strike can generate conditions in the lightning channel with a majority of positive nitrogen ions, and a minority of negative oxygen ions and electrons. The calculations are initiated with electrons included; however, at the moderate ion densities chosen the electrons are rapidly lost to form negative ions, and after 1 µ s their influence on the ion dynamics is negligible. Further development after 1 µ s is followed using a simpler set of equations involving only positive ions and negative ions, but including ion diffusion. The space-charge electric field generated by the majority positive ions drives them from the centre of the distribution and drives the minority negative ions and electrons towards the centre of the distribution. In the central region the positive and negative ion distributions eventually overlap exactly and their space-charge fields cancel resulting in zero electric field, and the plasma ball formed is quite stable for a number of seconds. The formation of such plasma balls is not critically dependent on the initial diameter of the ion distributions, or the initial density of minority negative ions. The ion densities decrease relatively slowly due to mutual neutralization of positive and negative ions. The radiation from this neutralization process involving positive nitrogen ions and negative oxygen ions is not sufficient to account for the reported luminosity of ball lightning and some other source of luminosity is shown to be required; the plasma ball model used could readily incorporate other ions in order to account for the luminosity and range of colours reported for ball

  13. Collapse and revival of entanglement between qubits coupled to a spin coherent state

    Science.gov (United States)

    Bahari, Iskandar; Spiller, Timothy P.; Dooley, Shane; Hayes, Anthony; McCrossan, Francis

    We extend the study of the Jayne-Cummings (JC) model involving a pair of identical two-level atoms (or qubits) interacting with a single mode quantized field. We investigate the effects of replacing the radiation field mode with a composite spin, comprising N qubits, or spin-1/2 particles. This model is relevant for physical implementations in superconducting circuit QED, ion trap and molecular systems. For the case of the composite spin prepared in a spin coherent state, we demonstrate the similarities of this set-up to the qubits-field model in terms of the time evolution, attractor states and in particular the collapse and revival of the entanglement between the two qubits. We extend our analysis by taking into account an effect due to qubit imperfections. We consider a difference (or “mismatch”) in the dipole interaction strengths of the two qubits, for both the field mode and composite spin cases. To address decoherence due to this mismatch, we then average over this coupling strength difference with distributions of varying width. We demonstrate in both the field mode and the composite spin scenarios that increasing the width of the “error” distribution increases suppression of the coherent dynamics of the coupled system, including the collapse and revival of the entanglement between the qubits.

  14. Gravitational collapse and the vacuum energy

    International Nuclear Information System (INIS)

    Campos, M

    2014-01-01

    To explain the accelerated expansion of the universe, models with interacting dark components (dark energy and dark matter) have been considered recently in the literature. Generally, the dark energy component is physically interpreted as the vacuum energy of the all fields that fill the universe. As the other side of the same coin, the influence of the vacuum energy on the gravitational collapse is of great interest. We study such collapse adopting different parameterizations for the evolution of the vacuum energy. We discuss the homogeneous collapsing star fluid, that interacts with a vacuum energy component, using the stiff matter case as example. We conclude this work with a discussion of the Cahill-McVittie mass for the collapsed object.

  15. Simple Analytic Models of Gravitational Collapse

    Energy Technology Data Exchange (ETDEWEB)

    Adler, R.

    2005-02-09

    Most general relativity textbooks devote considerable space to the simplest example of a black hole containing a singularity, the Schwarzschild geometry. However only a few discuss the dynamical process of gravitational collapse, by which black holes and singularities form. We present here two types of analytic models for this process, which we believe are the simplest available; the first involves collapsing spherical shells of light, analyzed mainly in Eddington-Finkelstein coordinates; the second involves collapsing spheres filled with a perfect fluid, analyzed mainly in Painleve-Gullstrand coordinates. Our main goal is pedagogical simplicity and algebraic completeness, but we also present some results that we believe are new, such as the collapse of a light shell in Kruskal-Szekeres coordinates.

  16. Bounds on quantum collapse models from matter-wave interferometry: calculational details

    Science.gov (United States)

    Toroš, Marko; Bassi, Angelo

    2018-03-01

    We present a simple derivation of the interference pattern in matter-wave interferometry predicted by a class of quantum master equations. We apply the obtained formulae to the following collapse models: the Ghirardi-Rimini-Weber (GRW) model, the continuous spontaneous localization (CSL) model together with its dissipative (dCSL) and non-Markovian generalizations (cCSL), the quantum mechanics with universal position localization (QMUPL), and the Diósi-Penrose (DP) model. We discuss the separability of the dynamics of the collapse models along the three spatial directions, the validity of the paraxial approximation, and the amplification mechanism. We obtain analytical expressions both in the far field and near field limits. These results agree with those already derived in the Wigner function formalism. We compare the theoretical predictions with the experimental data from two recent matter-wave experiments: the 2012 far-field experiment of Juffmann T et al (2012 Nat. Nanotechnol. 7 297-300) and the 2013 Kapitza-Dirac-Talbot-Lau (KDTL) near-field experiment of Eibenberger et al (2013 Phys. Chem. Chem. Phys. 15 14696-700). We show the region of the parameter space for each collapse model that is excluded by these experiments. We show that matter-wave experiments provide model-insensitive bounds that are valid for a wide family of dissipative and non-Markovian generalizations.

  17. Refinement of Crystalline Boron and the Superconducting Properties of MgB2 by Attrition Ball Milling

    International Nuclear Information System (INIS)

    Lee, J. H.; Shin, S. Y.; Park, H. W.; Jun, B. H.; Kim, C. J.

    2008-01-01

    We report refinement of crystalline boron by an attrition ball milling system and the superconducting properties of the MgB 2 pellets prepared from the refined boron. In this work, we have conducted the ball milling with only crystalline boron powder, in order to improve homogeneity and control the grain size of the MgB 2 that is formed from it. We observed that the crystalline responses in the ball-milled boron became broader and weaker when the ball-milling time was further increased. On the other hand, the B 2 O 3 peak became stronger in the powders, resulting in an increase in the amount of MgO within the MgB 2 volume. The main reason for this is a greater oxygen uptake. From the perspective of the superconducting properties, however, the sample prepared from boron that was ball milled for 5 hours showed an improvement of critical current density (J c ), even with increased MgO phase, under an external magnetic field at 5 and 20 K.

  18. Asymmetric core collapse of rapidly rotating massive star

    Science.gov (United States)

    Gilkis, Avishai

    2018-02-01

    Non-axisymmetric features are found in the core collapse of a rapidly rotating massive star, which might have important implications for magnetic field amplification and production of a bipolar outflow that can explode the star, as well as for r-process nucleosynthesis and natal kicks. The collapse of an evolved rapidly rotating MZAMS = 54 M⊙ star is followed in three-dimensional hydrodynamic simulations using the FLASH code with neutrino leakage. A rotating proto-neutron star (PNS) forms with a non-zero linear velocity. This can contribute to the natal kick of the remnant compact object. The PNS is surrounded by a turbulent medium, where high shearing is likely to amplify magnetic fields, which in turn can drive a bipolar outflow. Neutron-rich material in the PNS vicinity might induce strong r-process nucleosynthesis. The rapidly rotating PNS possesses a rotational energy of E_rot ≳ 10^{52} erg. Magnetar formation proceeding in a similar fashion will be able to deposit a portion of this energy later on in the supernova ejecta through a spin-down mechanism. These processes can be important for rare supernovae generated by rapidly rotating progenitors, even though a complete explosion is not simulated in the present study.

  19. On the Induced Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    M. Becerra Laura

    2018-01-01

    Full Text Available The induced gravitational collapse (IGC paradigm has been applied to explain the long gamma ray burst (GRB associated with type Ic supernova, and recently the Xray flashes (XRFs. The progenitor is a binary systems of a carbon-oxygen core (CO and a neutron star (NS. The CO core collapses and undergoes a supernova explosion which triggers the hypercritical accretion onto the NS companion (up to 10-2 M⊙s-1. For the binary driven hypernova (BdHNe, the binary system is enough bound, the NS reach its critical mass, and collapse to a black hole (BH with a GRB emission characterized by an isotropic energy Eiso > 1052 erg. Otherwise, for binary systems with larger binary separations, the hypercritical accretion onto the NS is not sufficient to induced its gravitational collapse, a X-ray flash is produced with Eiso < 1052 erg. We’re going to focus in identify the binary parameters that limits the BdHNe systems with the XRFs systems.

  20. Gravity induced wave function collapse

    Science.gov (United States)

    Gasbarri, G.; Toroš, M.; Donadi, S.; Bassi, A.

    2017-11-01

    Starting from an idea of S. L. Adler [in Quantum Nonlocality and Reality: 50 Years of Bell's Theorem, edited by M. Bell and S. Gao (Cambridge University Press, Cambridge, England 2016)], we develop a novel model of gravity induced spontaneous wave function collapse. The collapse is driven by complex stochastic fluctuations of the spacetime metric. After deriving the fundamental equations, we prove the collapse and amplification mechanism, the two most important features of a consistent collapse model. Under reasonable simplifying assumptions, we constrain the strength ξ of the complex metric fluctuations with available experimental data. We show that ξ ≥10-26 in order for the model to guarantee classicality of macro-objects, and at the same time ξ ≤10-20 in order not to contradict experimental evidence. As a comparison, in the recent discovery of gravitational waves in the frequency range 35 to 250 Hz, the (real) metric fluctuations reach a peak of ξ ˜10-21.

  1. Knee Angle and Stride Length in Association with Ball Speed in Youth Baseball Pitchers

    Directory of Open Access Journals (Sweden)

    Bart van Trigt

    2018-05-01

    Full Text Available The purpose of this study was to determine whether stride length and knee angle of the leading leg at foot contact, at the instant of maximal external rotation of the shoulder, and at ball release are associated with ball speed in elite youth baseball pitchers. In this study, fifty-two elite youth baseball pitchers (mean age 15.2 SD (standard deviation 1.7 years pitched ten fastballs. Data were collected with three high-speed video cameras at a frequency of 240 Hz. Stride length and knee angle of the leading leg were calculated at foot contact, maximal external rotation, and ball release. The associations between these kinematic variables and ball speed were separately determined using generalized estimating equations. Stride length as percentage of body height and knee angle at foot contact were not significantly associated with ball speed. However, knee angles at maximal external rotation and ball release were significantly associated with ball speed. Ball speed increased by 0.45 m/s (1 mph with an increase in knee extension of 18 degrees at maximal external rotation and 19.5 degrees at ball release. In conclusion, more knee extension of the leading leg at maximal external rotation and ball release is associated with higher ball speeds in elite youth baseball pitchers.

  2. Nonlinear wave collapse and strong turbulence

    International Nuclear Information System (INIS)

    Robinson, P.A.

    1997-01-01

    The theory and applications of wave self-focusing, collapse, and strongly nonlinear wave turbulence are reviewed. In the last decade, the theory of these phenomena and experimental realizations have progressed rapidly. Various nonlinear wave systems are discussed, but the simplest case of collapse and strong turbulence of Langmuir waves in an unmagnetized plasma is primarily used in explaining the theory and illustrating the main ideas. First, an overview of the basic physics of linear waves and nonlinear wave-wave interactions is given from an introductory perspective. Wave-wave processes are then considered in more detail. Next, an introductory overview of the physics of wave collapse and strong turbulence is provided, followed by a more detailed theoretical treatment. Later sections cover numerical simulations of Langmuir collapse and strong turbulence and experimental applications to space, ionospheric, and laboratory plasmas, including laser-plasma and beam-plasma interactions. Generalizations to self-focusing, collapse, and strong turbulence of waves in other systems are also discussed, including nonlinear optics, solid-state systems, magnetized auroral and astrophysical plasmas, and deep-water waves. The review ends with a summary of the main ideas of wave collapse and strong-turbulence theory, a collection of open questions in the field, and a brief discussion of possible future research directions. copyright 1997 The American Physical Society

  3. 3D Seismic Imaging over a Potential Collapse Structure

    Science.gov (United States)

    Gritto, Roland; O'Connell, Daniel; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

    2016-04-01

    The Middle-East has seen a recent boom in construction including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, however, the development areas need to be investigated to determine their suitability for the planned project. Subsurface parameters such as the type of material (soil/rock), thickness of top soil or rock layers, depth and elastic parameters of basement, for example, comprise important information needed before a decision concerning the suitability of the site for construction can be made. A similar problem arises in environmental impact studies, when subsurface parameters are needed to assess the geological heterogeneity of the subsurface. Environmental impact studies are typically required for each construction project, particularly for the scale of the aforementioned building boom in the Middle East. The current study was conducted in Qatar at the location of a future highway interchange to evaluate a suite of 3D seismic techniques in their effectiveness to interrogate the subsurface for the presence of karst-like collapse structures. The survey comprised an area of approximately 10,000 m2 and consisted of 550 source- and 192 receiver locations. The seismic source was an accelerated weight drop while the geophones consisted of 3-component 10 Hz velocity sensors. At present, we analyzed over 100,000 P-wave phase arrivals and performed high-resolution 3-D tomographic imaging of the shallow subsurface. Furthermore, dispersion analysis of recorded surface waves will be performed to obtain S-wave velocity profiles of the subsurface. Both results, in conjunction with density estimates, will be utilized to determine the elastic moduli of the subsurface rock layers.

  4. Dynamic analysis of double-row self-aligning ball bearings due to applied loads, internal clearance, surface waviness and number of balls

    Science.gov (United States)

    Zhuo, Yaobin; Zhou, Xiaojun; Yang, Chenlong

    2014-11-01

    In this paper, a three degrees of freedom (dof) model was established for a double-row self-aligning ball bearing (SABB) system, and was applied to study the dynamic behavior of the system during starting process and constant speed rotating process. A mathematical model was developed concerning stiffness and damping characteristics of the bearing, as well as three-dimensional applied load, rotor centrifugal force, etc. Balls and races were all considered as nonlinear springs, and the contact force between ball and race was calculated based on classic Hertzian elastic contact deformation theory and deformation compatibility theory. The changes of each ball's contact force and loaded angle of each row were taken into account. In order to solve the nonlinear dynamical equilibrium equations of the system, these equations were rewritten as differential equations and the fourth order Runge-Kutta method was used to solve the equations iteratively. In order to verify accuracy of the dynamical model and correctness of the numerical solution method, a kind of SABB-BRF30 was chosen for case studies. The effects of several important governing parameters, such as radial and axial applied loads, normal internal, inner and outer races waviness, and number of balls were investigated. These parametric studies led to a complete characterization of the shaft-bearing system vibration transmission. The research provided a theoretical reference for new type bearing design, shaft-bearing system kinetic analysis, optimal design, etc.

  5. An overview of Ball Aerospace cryogen storage and delivery systems

    International Nuclear Information System (INIS)

    Marquardt, J; Keller, J; Mills, G; Schmidt, J

    2015-01-01

    Starting on the Gemini program in the 1960s, Beech Aircraft (now Ball Aerospace) has been designing and manufacturing dewars for a variety of cryogens including liquid hydrogen and oxygen. These dewars flew on the Apollo, Skylab and Space Shuttle spacecraft providing fuel cell reactants resulting in over 150 manned spaceflights. Since Space Shuttle, Ball has also built the liquid hydrogen fuel tanks for the Boeing Phantom Eye unmanned aerial vehicle. Returning back to its fuel cell days, Ball has designed, built and tested a volume-constrained liquid hydrogen and oxygen tank system for reactant delivery to fuel cells on unmanned undersea vehicles (UUVs). Herein past history of Ball technology is described. Testing has been completed on the UUV specific design, which will be described. (paper)

  6. Z(λ) model and flows: subgraph break-collapse method

    International Nuclear Information System (INIS)

    Essam, J.W.; Magalhaes, A.C.N. de.

    1988-01-01

    A recursive algorithm previously developed for the λ-state Potts model is generalised to the Z(λ) model. The relations used are based on an expression we derive for the pair correlation function in terms of mod-λ flows, which represents an extension of a similar result for the partition function previously obtained by Biggs. The use of flows enables us to prove and extend the formulae which appear in the break-collapse method of Mariz and coworkers. It is argued that the use of of fixed-flow bonds rather than the precollapsed bonds used by the latter authors leads to a more efficient algorithm. (author) [pt

  7. A Novel Generic Ball Recognition Algorithm Based on Omnidirectional Vision for Soccer Robots

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2013-11-01

    Full Text Available It is significant for the final goal of RoboCup to realize the recognition of generic balls for soccer robots. In this paper, a novel generic ball recognition algorithm based on omnidirectional vision is proposed by combining the modified Haar-like features and AdaBoost learning algorithm. The algorithm is divided into offline training and online recognition. During the phase of offline training, numerous sub-images are acquired from various panoramic images, including generic balls, and then the modified Haar-like features are extracted from them and used as the input of the AdaBoost learning algorithm to obtain a classifier. During the phase of online recognition, and according to the imaging characteristics of our omnidirectional vision system, rectangular windows are defined to search for the generic ball along the rotary and radial directions in the panoramic image, and the learned classifier is used to judge whether a ball is included in the window. After the ball has been recognized globally, ball tracking is realized by integrating a ball velocity estimation algorithm to reduce the computational cost. The experimental results show that good performance can be achieved using our algorithm, and that the generic ball can be recognized and tracked effectively.

  8. Effect of Kinesiotape Applications on Ball Velocity and Accuracy in Amateur Soccer and Handball.

    Science.gov (United States)

    Müller, Carsten; Brandes, Mirko

    2015-12-22

    Evidence supporting performance enhancing effects of kinesiotape in sports is missing. The aims of this study were to evaluate effects of kinesiotape applications with regard to shooting and throwing performance in 26 amateur soccer and 32 handball players, and to further investigate if these effects were influenced by the players' level of performance. Ball speed as the primary outcome and accuracy of soccer kicks and handball throws were analyzed with and without kinesiotape by means of radar units and video recordings. The application of kinesiotapes significantly increased ball speed in soccer by 1.4 km/h (p=0.047) and accuracy with a lesser distance from the target by -6.9 cm (p=0.039). Ball velocity in handball throws also significantly increased by 1.2 km/h (p=0.013), while accuracy was deteriorated with a greater distance from the target by 3.4 cm (p=0.005). Larger effects with respect to ball speed were found in players with a lower performance level in kicking (1.7 km/h, p=0.028) and throwing (1.8 km/h, p=0.001) compared with higher level soccer and handball players (1.2 km/h, p=0.346 and 0.5 km/h, p=0.511, respectively). In conclusion, the applications of kinesiotape used in this study might have beneficial effects on performance in amateur soccer, but the gain in ball speed in handball is counteracted by a significant deterioration of accuracy. Subgroup analyses indicate that kinesiotape may yield larger effects on ball velocity in athletes with lower kicking and throwing skills.

  9. Collapse dynamics of ultrasound contrast agent microbubbles

    Science.gov (United States)

    King, Daniel Alan

    the size distributions of these UCAs, it is shown that the shell material has a large influence on the occurrence of postexcitation rebound at all tested frequencies while moderate alteration of the size distribution may only play a significant role within certain frequency ranges. Finally, the conditions which generate the experimental postexcitation signal are examined theoretically using several forms of single bubble models. Evidence is provided for the usefulness of modeling this large amplitude UCA behavior with a size-varying surface tension as described in the Marmottant model; better agreement for lipid-shelled Definity UCAs is obtained by considering the dynamic response with a rupturing shell rather than either a non-rupturing or nonexistent shell. Moreover, the modeling indicates that maximum radial expansion from the initial UCA size is a suitable metric to predict postexcitation collapse, and that both shell rupture and inertial cavitation are necessary conditions to generate this behavior. Postexcitation analysis is found to be a beneficial characterization metric for studying the destruction behaviors of single UCAs when measured with the double PCD setup. This work provides quantitative documentation of UCA collapse, exploration into UCA material properties which affect this collapse, and comparison of existing single bubble models with experimentally measured postexcitation signals.

  10. A UAV BASED 3-D POSITIONING FRAMEWORK FOR DETECTING LOCATIONS OF BURIED PERSONS IN COLLAPSED DISASTER AREA

    Directory of Open Access Journals (Sweden)

    H. Moon

    2016-06-01

    Full Text Available Regarding spatial location positioning, indoor location positioning theories based on wireless communication techniques such as Wi-Fi, beacon, UWB and Bluetooth has widely been developing across the world. These techniques are mainly focusing on spatial location detection of customers using fixed wireless APs and unique Tags in the indoor environment. Besides, since existing detection equipment and techniques using ultrasound or sound etc. to detect buried persons and identify survival status for them cause 2nd damages on the collapsed debris for rescuers. In addition, it might take time to check the buried persons. However, the collapsed disaster sites should consider both outdoor and indoor environments because empty spaces under collapsed debris exists. In order to detect buried persons from the empty spaces, we should collect wireless signals with Wi-Fi from their mobile phone. Basically, the Wi-Fi signal measure 2-D location. However, since the buried persons have Z value with burial depth, we also should collect barometer sensor data from their mobile phones in order to measure Z values according to weather conditions. Specially, for quick accessibility to the disaster area, a drone (UAV; Unmanned Arial Vehicle system, which is equipped with a wireless detection module, was introduced. Using these framework, this study aims to provide the rescuers with effective rescue information by calculating 3-D location for buried persons based on the wireless and barometer sensor fusion.

  11. Ball Games of Native American Women of the Plains.

    Science.gov (United States)

    Pesavento, Wilma J.

    The problem under investigation concerned (1) determining the ball games of Native American girls and women of the Great Plains, (2) determining the geographical spread of the games within the culture area, and (3) determining the characteristics of the various games. Data for this investigation were obtained from the 48 "Annual Reports of the…

  12. Is intrathoracic tracheal collapsibility correlated to clinical phenotypes and sex in patients with COPD?

    Directory of Open Access Journals (Sweden)

    Camiciottoli G

    2015-04-01

    Full Text Available Gianna Camiciottoli,1 Stefano Diciotti,2 Francesca Bigazzi,1 Simone Lombardo,3 Maurizio Bartolucci,4 Matteo Paoletti,1 Mario Mascalchi,3 Massimo Pistolesi1 1Section of Respiratory Medicine, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy; 2Department of Electrical, Electronic, and Information Engineering “Guglielmo Marconi,” University of Bologna, Cesena, Italy; 3Radiodiagnostic Section, Department of Clinical and Experimental Biomedical Sciences, University of Florence, Florence, Italy; 4Department of Diagnostic Imaging, Careggi University Hospital, Florence, Italy Abstract: A substantial proportion of patients with chronic obstructive pulmonary disease (COPD develops various degree of intrathoracic tracheal collapsibility. We studied whether the magnitude of intrathoracic tracheal collapsibility could be different across clinical phenotypes and sex in COPD. Intrathoracic tracheal collapsibility measured at paired inspiratory–expiratory low dose computed tomography (CT and its correlation with clinical, functional, and CT-densitometric data were investigated in 69 patients with COPD according to their predominant conductive airway or emphysema phenotypes and according to sex. Intrathoracic tracheal collapsibility was higher in patients with predominant conductive airway disease (n=28 and in females (n=27. Women with a predominant conductive airway phenotype (n=10 showed a significantly greater degree of collapsibility than women with predominant emphysema (28.9%±4% versus 11.6%±2%; P<0.001. Intrathoracic tracheal collapsibility was directly correlated with inspiratory–expiratory volume variation at CT and with forced expiratory volume (1 second, and inversely correlated with reduced CT lung density and functional residual capacity. Intrathoracic tracheal collapsibility was not correlated with cough and wheezing; however, intrathoracic tracheal collapsibility and clinical phenotypes of COPD

  13. The head tracks and gaze predicts: how the world's best batters hit a ball.

    Directory of Open Access Journals (Sweden)

    David L Mann

    Full Text Available Hitters in fast ball-sports do not align their gaze with the ball throughout ball-flight; rather, they use predictive eye movement strategies that contribute towards their level of interceptive skill. Existing studies claim that (i baseball and cricket batters cannot track the ball because it moves too quickly to be tracked by the eyes, and that consequently (ii batters do not - and possibly cannot - watch the ball at the moment they hit it. However, to date no studies have examined the gaze of truly elite batters. We examined the eye and head movements of two of the world's best cricket batters and found both claims do not apply to these batters. Remarkably, the batters coupled the rotation of their head to the movement of the ball, ensuring the ball remained in a consistent direction relative to their head. To this end, the ball could be followed if the batters simply moved their head and kept their eyes still. Instead of doing so, we show the elite batters used distinctive eye movement strategies, usually relying on two predictive saccades to anticipate (i the location of ball-bounce, and (ii the location of bat-ball contact, ensuring they could direct their gaze towards the ball as they hit it. These specific head and eye movement strategies play important functional roles in contributing towards interceptive expertise.

  14. Micro-ball lens structure fabrication based on drop on demand printing the liquid mold

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyang, E-mail: zhuxy1026@163.com; Zhu, Li, E-mail: zhuli@njust.edu.cn; Chen, Hejuan; Yang, Lijun; Zhang, Weiyi

    2016-01-15

    Graphical abstract: - Highlights: • The glycerol micro-ball droplet was introduced to be as liquid mold to fabricate micro-ball lens. • A molding process was used to fabricate the micro-ball lens and the scales of them can be controlled. • The accurate molding process is mainly attributed to the ultrahigh adhesion of the treated substrate. • The micro-ball lenses with contact angle of 120° and 150° were fabricated, analyzed and discussed. - Abstract: In this paper, we demonstrated a simple micro-ball lens array (MBLA) fabrication method using a drop-on-demand (DOD) droplet printing technique and liquid mold. The micro-ball droplet array on the hydrophobic surface is used as the liquid mold to fabricate the MBLA. The ultrahigh adhesion force between the micro-ball droplet and the substrate is ascribed to the Wenzel state of the micro-ball droplet, while the replication process with low position error is attributed to the ultrahigh adhesion force between the micro-ball droplet and the substrate and the high viscosity of the micro-ball droplet and polydimethylsiloxane (PDMS) liquid. The micro-ball lenses (MBLs) with a contact angle of 120° and 150° were fabricated and the important fabrication details were discussed. The optical performance and scanning electron microscope (SEM) data of the MBLs showed that the MBLs had high quality surface morphology and good optical performance.

  15. 32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry.

    Science.gov (United States)

    Wiggins, G C; Triantafyllou, C; Potthast, A; Reykowski, A; Nittka, M; Wald, L L

    2006-07-01

    A 32-channel 3T receive-only phased-array head coil was developed for human brain imaging. The helmet-shaped array was designed to closely fit the head with individual overlapping circular elements arranged in patterns of hexagonal and pentagonal symmetry similar to that of a soccer ball. The signal-to-noise ratio (SNR) and noise amplification (g-factor) in accelerated imaging applications were quantitatively evaluated in phantom and human images and compared with commercially available head coils. The 32-channel coil showed SNR gains of up to 3.5-fold in the cortex and 1.4-fold in the corpus callosum compared to a (larger) commercial eight-channel head coil. The experimentally measured g-factor performance of the helmet array showed significant improvement compared to the eight-channel array (peak g-factor 59% and 26% of the eight-channel values for four- and fivefold acceleration). The performance of the arrays is demonstrated in high-resolution and highly accelerated brain images. Copyright (c) 2006 Wiley-Liss, Inc.

  16. Predicting brain acceleration during heading of soccer ball

    Science.gov (United States)

    Taha, Zahari; Hasnun Arif Hassan, Mohd; Azri Aris, Mohd; Anuar, Zulfika

    2013-12-01

    There has been a long debate whether purposeful heading could cause harm to the brain. Studies have shown that repetitive heading could lead to degeneration of brain cells, which is similarly found in patients with mild traumatic brain injury. A two-degree of freedom linear mathematical model was developed to study the impact of soccer ball to the brain during ball-to-head impact in soccer. From the model, the acceleration of the brain upon impact can be obtained. The model is a mass-spring-damper system, in which the skull is modelled as a mass and the neck is modelled as a spring-damper system. The brain is a mass with suspension characteristics that are also defined by a spring and a damper. The model was validated by experiment, in which a ball was dropped from different heights onto an instrumented dummy skull. The validation shows that the results obtained from the model are in a good agreement with the brain acceleration measured from the experiment. This findings show that a simple linear mathematical model can be useful in giving a preliminary insight on what human brain endures during a ball-to-head impact.

  17. Cross-class resistance to non-beta-lactam antimicrobials in extended-spectrum beta-lactamase-producing Klebsiella pneumoniae.

    Science.gov (United States)

    Procop, Gary W; Tuohy, Marion J; Wilson, Deborah A; Williams, Delisa; Hadziyannis, Emilia; Hall, Gerri S

    2003-08-01

    Extended spectrum beta-lactamases are modified beta-lactamase enzymes that impart resistance to third-generation cephalosporins and make all beta-lactam antibiotics and cephalosporins useless for therapy. We compared the antimicrobial susceptibility profiles of extended-spectrum beta-lactamase (ESBL)-producing and non-ESBL-producing isolates of Klebsiella pneumoniae. The ESBL producers had significantly diminished susceptibility compared with the non-ESBL producers for gentamicin (P < .001), tobramycin (P < .001), amikacin (P < .005), trimethoprim-sulfamethoxazole (P < .01), ciprofloxacin (P < .001), and nitrofurantoin (P < .001). All isolates were susceptible to imipenem. ESBL-producing K pneumoniae may also be resistant to non-beta-lactam antibiotics. Therefore, susceptibility testing of these isolates is critical for guiding therapy.

  18. Distinct Element modeling of geophysical signatures during sinkhole collapse

    Science.gov (United States)

    Al-Halbouni, Djamil; Holohan, Eoghan P.; Taheri, Abbas; Dahm, Torsten

    2017-04-01

    A sinkhole forms due to the collapse of rocks or soil near the Earth's surface into an underground cavity. Such cavities represent large secondary pore spaces derived by dissolution and subrosion in the underground. By changing the stress field in the surrounding material, the growth of cavities can lead to a positive feedback, in which expansion and mechanical instability in the surrounding material increases or generates new secondary pore space (e.g. by fracturing), which in turn increases the cavity size, etc. A sinkhole forms due to the eventual subsidence or collapse of the overburden that becomes destabilized and fails all the way to the Earth's surface. Both natural processes like (sub)surface water movement and earthquakes, and human activities, such as mining, construction and groundwater extraction, intensify such feedbacks. The development of models for the mechanical interaction of a growing cavity and fracturing of its surrounding material, thus capturing related precursory geophysical signatures, has been limited, however. Here we report on the advances of a general, simplified approach to simulating cavity growth and sinkhole formation by using 2D Distinct Element Modeling (DEM) PFC5.0 software and thereby constraining pre-, syn- and post-collapse geophysical and geodetic signatures. This physically realistic approach allows for spontaneous cavity development and dislocation of rock mass to be simulated by bonded particle formulation of DEM. First, we present calibration and validation of our model. Surface subsidence above an instantaneously excavated circular cavity is tracked and compared with an incrementally increasing dissolution zone both for purely elastic and non-elastic material.This validation is important for the optimal choice of model dimensions and particles size with respect to simulation time. Second, a cavity growth approach is presented and compared to a well-documented case study, the deliberately intensified sinkhole collapse at

  19. The methodology of composing the exercises system with fit balls.

    Directory of Open Access Journals (Sweden)

    Voronov N.P.

    2011-02-01

    Full Text Available The original methodology of composing the exercises system with fit balls was considered. More than 10 publications were analysed. On the lesson with fit balls the problem was revealed. In the experiment took part 30 students at the age from 18 till 21. All the famous exercises were systematized. As a result, a big attractiveness and assimilability of the proposed complex was revealed. The effectiveness of the complex of physical exercises with fit balls for students was proved.

  20. Degeneration of articular cartilage in osteonecrosis of the femoral head begins at the necrotic region after collapse: a preliminary study using T1 rho MRI

    Energy Technology Data Exchange (ETDEWEB)

    Sonoda, Kazuhiko; Motomura, Goro; Nakashima, Yasuharu [Kyushu University, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Higashi-ku, Fukuoka (Japan); Kawanami, Satoshi; Takayama, Yukihisa; Honda, Hiroshi [Kyushu University, Department of Clinical Radiology, Graduate School of Medical Sciences, Higashi-ku, Fukuoka (Japan); Yamamoto, Takuaki [Fukuoka University, Department of Orthopaedic Surgery, Faculty of Medicine, Jonan-ku, Fukuoka (Japan)

    2017-04-15

    The purpose of this study is to evaluate the role of collapse on the degeneration of articular cartilage in patients with osteonecrosis of the femoral head (ONFH). Sixteen hips in 12 patients (four men, eight women; mean age, 34.8 years) with a history of systemic corticosteroid treatment were studied using T1 rho magnetic resonance imaging (MRI). Six hips had collapsed ONFH, five had non-collapsed ONFH, and five had no osteonecrosis (controls). Using oblique coronal images, we divided the articular surface of necrotic femoral heads into a region just above the necrotic bone (necrotic zone) and another above the living bone (living zone). T1 rho value was evaluated for each zone. The mean T1 rho value in the necrotic zone was significantly higher in the collapsed ONFH group (48.4 ± 2.7 ms) than in the non-collapsed ONFH group (41.0 ± 0.9 ms). In the collapsed ONFH group, the mean T1 rho value was significantly higher in the necrotic zone (48.4 ± 2.7 ms) than in the living zone (43.5 ± 2.5 ms). In the non-collapsed ONFH group, there was no significant difference between the mean T1 rho values of the necrotic and living zones. In the collapsed ONFH group, the mean T1 rho value of the necrotic zone and the interval from pain onset to the MRI examination were positively correlated. The current T1 rho MRI study suggested that the degeneration of articular cartilage in ONFH begins at the necrotic region after collapse. (orig.)

  1. C, N co-doped TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite coatings prepared from TiC{sub 0.7}N{sub 0.3} powder using ball milling followed by oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Liang, E-mail: haoliang@tust.edu.cn [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Wang, Zhenwei, E-mail: 1004329228@qq.com [School of Naval Architecture and Ocean Engineering, Harbin Institute of Technology, Weihai, No. 2, Wenhua West Road, Weihai 264209 (China); Zheng, Yaoqing, E-mail: 13612177268@163.com [College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Li, Qianqian, E-mail: 1482471595@qq.com [College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Guan, Sujun, E-mail: sujunguan1221@gmail.com [College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Zhao, Qian, E-mail: zhaoqian@tust.edu.cn [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Cheng, Lijun, E-mail: chenglijun@tust.edu.cn [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); Lu, Yun, E-mail: luyun@faculty.chiba-u.jp [College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Liu, Jizi, E-mail: jzliu@njust.edu.cn [Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, No. 200, Xiaolingwei Street, Nanjing 210094 (China)

    2017-01-01

    Highlights: • TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} coatings were prepared by ball milling followed by oxidation. • In situ co-doping of C and N with simultaneous TiO{sub 2} formation was observed. • Improved photocatalytic activity under UV/visible light was noticed. • Synergism in co-doping and heterojunction formation promoted carrier separation. - Abstract: Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO{sub 2} coatings on the surfaces of Al{sub 2}O{sub 3} balls from TiC{sub 0.7}N{sub 0.3} powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV–vis). The results show that continuous TiC{sub 0.7}N{sub 0.3} coatings were formed after ball milling. C, N co-doped TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite coatings were prepared after the direct oxidization of TiC{sub 0.7}N{sub 0.3} coatings in the atmosphere. However, TiO{sub 2} was hardly formed in the surface layer of TiC{sub 0.7}N{sub 0.3} coatings within a depth less than 10 nm during the heat oxidation of TiC{sub 0.7}N{sub 0.3} coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO{sub 2}/TiC{sub 0.7}N{sub 0.3} composite microstructure.

  2. Neutrinos from gravitational collapse

    International Nuclear Information System (INIS)

    Mayle, R.; Wilson, J.R.; Schramm, D.N.

    1986-05-01

    Detailed calculations are made of the neutrino spectra emitted during gravitational collapse events (Type II supernovae). Those aspects of the neutrino signal which are relatively independent of the collapse model and those aspects which are sensitive to model details are discussed. The easier-to-detect high energy tail of the emitted neutrinos has been calculated using the Boltzmann equation which is compared with the result of the traditional multi-group flux limited diffusion calculations. 8 figs., 28 refs

  3. Developing empirical collapse fragility functions for global building types

    Science.gov (United States)

    Jaiswal, K.; Wald, D.; D'Ayala, D.

    2011-01-01

    Building collapse is the dominant cause of casualties during earthquakes. In order to better predict human fatalities, the U.S. Geological Survey’s Prompt Assessment of Global Earthquakes for Response (PAGER) program requires collapse fragility functions for global building types. The collapse fragility is expressed as the probability of collapse at discrete levels of the input hazard defined in terms of macroseismic intensity. This article provides a simple procedure for quantifying collapse fragility using vulnerability criteria based on the European Macroseismic Scale (1998) for selected European building types. In addition, the collapse fragility functions are developed for global building types by fitting the beta distribution to the multiple experts’ estimates for the same building type (obtained from EERI’s World Housing Encyclopedia (WHE)-PAGER survey). Finally, using the collapse probability distributions at each shaking intensity level as a prior and field-based collapse-rate observations as likelihood, it is possible to update the collapse fragility functions for global building types using the Bayesian procedure.

  4. PARAMETER DETERMINATION FOR ADDITIONAL OPERATING FORCE MECHANISM IN DEVICE FOR PNEUMO-CENTRIFUGAL MACHINING OF BALL-SHAPED WORKPIECES

    Directory of Open Access Journals (Sweden)

    A. A. Sukhotsky

    2014-01-01

    Full Text Available The paper describes development of the methodology for optimization of parameters for an additional operating force mechanism in a device for pneumo-centrifugal machining of glass balls. Specific feature in manufacturing glass balls for micro-optics in accordance with technological process for obtaining ball-shaped workpieces is grinding and polishing of spherical surface in a free state. In this case component billets of future balls are made in the form of cubes and the billets are given preliminary a form of ball with the help of rough grinding. An advanced method for obtaining ball-shaped work-pieces from brittle materials is a pneumocentrifugal machining. This method presupposes an application of two conic rings with abrasive working surfaces which are set coaxially with large diameters to each other and the billets are rolled along these rings. Rotation of the billets is conveyed by means of pressure medium.The present devices for pneumo-centrifugal machining are suitable for obtaining balls up to 6 mm. Machining of the work-pieces with full spherical surfaces and large diameter is non-productive due to impossibility to ensure a sufficient force on the billet in the working zone. For this reason the paper proposes a modified device where an additional force on the machined billet is created by upper working disc that is making a reciprocating motion along an axis of abrasive conic rings. The motion is realized with the help of a cylindrical camshaft mechanism in the form of a ring with a profile working end face and the purpose of present paper is to optimize parameters of the proposed device.The paper presents expressions for calculation of constitutive parameters of the additional operating force mechanism including parameters of loading element motion, main dimensions of the additional operating force mechanism and parameters of a profile element in the additional operating force mechanism.Investigation method is a mathematical

  5. Effects of Hemibridge with Ball and Balloon Exercise on Forced Expiratory Volume and Pain in Patients with Chronic Low Back Pain: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Jorida Fernandes

    2017-08-01

    Full Text Available Background and objectives: Suboptimal breathing patterns and impairments of posture and trunk stability are often associated with musculoskeletal complaints such as low back pain. Respiration is also affected by poor neuromuscular control of core muscles. Immediate effects of hemibridge with ball and balloon exercise has been studied on chronic pain in athlete population. Objective: To evaluate the effects of hemibridge with ball and balloon exercise on pain, forced expiratory volume and functional abilities in patients with chronic low back pain using Visual Analogue Scale (VAS, Forced Expiratory Volume (FEV and Modified Oswestry Disability Questionnaire (MODQ. Methods: The present experimental study was conducted among 30 participants between the age of 21 to 55 years with chronic non-specific LBP. The participants were given a hemibridge with ball and balloon exercise. Pre-interventional and 3rd day Post-interventional outcome measurements were taken using VAS, FEV1 and FEV6 and MODQ. Results: The difference between pre-and post of VAS was statistically highly significant (p=0.0001. The p value of FEV6 and MODQ by paired t test was statistically significant with p value of 0.02 and 0.0007 respectively. Conclusion: The study concludes that there is an immediate effect of hemibridge with ball and balloon exercise on pain, FEV6 and functional ability in patients with chronic LBP.

  6. Extended supersymmetric BMS{sub 3} algebras and their free field realisations

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Nabamita [Indian Institute of Science Education and Research,Homi Bhabha Road, Pashan, Pune 411 008 (India); Jatkar, Dileep P. [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad, 211019 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India); Lodato, Ivano; Mukhi, Sunil; Neogi, Turmoli [Indian Institute of Science Education and Research,Homi Bhabha Road, Pashan, Pune 411 008 (India)

    2016-11-09

    We study N=(2,4,8) supersymmetric extensions of the three dimensional BMS algebra (BMS{sub 3}) with most generic possible central extensions. We find that N-extended supersymmetric BMS{sub 3} algebras can be derived by a suitable contraction of two copies of the extended superconformal algebras. Extended algebras from all the consistent contractions are obtained by scaling left-moving and right-moving supersymmetry generators symmetrically, while Virasoro and R-symmetry generators are scaled asymmetrically. On the way, we find that the BMS/GCA correspondence does not in general hold for supersymmetric systems. Using the β-γ and the b-c systems, we construct free field realisations of all the extended super-BMS{sub 3} algebras.

  7. O(d, - Collapse/inflation in Colliding Superstring Waves

    Science.gov (United States)

    Bozza, V.; Veneziano, G.

    2002-12-01

    The present formulation of pre-big bang cosmology relies on the principle of asymptotic past triviality (APT)1 , i.e. on the assumption that, in its initial state, the Universe was in a low-curvature, small-coupling regime and was thus adequately described in terms of the low-energy, tree-level effective action of string theory. The early universe can thus be visualized as a chaotic superposition of massless waves, seen as excitations over a trivial Minkowski background. The superposition of these perturbations can eventually lead to the gravitational collapse of the interaction region. Measuring distances in string units, such a collapse can become an inflationary, dilaton-driven, expansion. According to the scenario depicted in Ref. 1, the collapse/inflation of sufficiently large regions could then evolve in a universe resembling our own. An explicit example of this phenomenon was given by Feinstein, Kunze & Vázquez-Mozo2 who studied a particular exact solution of the field equations describing the collision of two four-dimensional gravi-dilatonic plane waves. In our work3, including from the start the Kalb-Ramond Bμν 2-form in an arbitrary number D of space-time dimensions we recover their result in a more general O(d, d)-invariant formulation, allowing a full investigation of a wider class of solutions. The two plane waves are taken to travel in opposite directions along the same axis, so that, assuming plane symmetry, all fields are functions of the time coordinate and the common direction of propagation z. The problem is thus endowed with d = D - 2 abelian isometries, the action being invariant for translations along the transverse directions. In this situation, it is possible to write the action in terms of the restriction of the metric on the non-trivial coordinates (t, z), the shifted dilaton and a 2d × 2d matrix M built by combining the remaining components of the metric and the antisymmetric field...

  8. The head tracks and gaze predicts: how the world's best batters hit the ball

    NARCIS (Netherlands)

    Mann, D.L.; Spratford, W.; Abernethy, B.

    2013-01-01

    Hitters in fast ball-sports do not align their gaze with the ball throughout ball-flight; rather, they use predictive eye movement strategies that contribute towards their level of interceptive skill. Existing studies claim that (i) baseball and cricket batters cannot track the ball because it moves

  9. Kicking velocity and physical, technical, tactical match performance for U18 female football players - effect of a new ball

    DEFF Research Database (Denmark)

    Andersen, Thomas B; Bendiksen, Mads; Pedersen, Jens M

    2012-01-01

    the new ball (NB) compared with the standard ball (SB) in a laboratory testing situation (23.2±0.4 vs. 22.4±0.3 ms(-1); p.05), but lower-limb muscular RPE was lower with NB (4.2±0.4 vs. 5.2±0.3; p.05). High-intensity running decreased (p.05). In conclusion, physiological demands were high in youth female...... football games, and decrements in running performance occurred towards the end of games. The players kicked faster and reported lower muscular exertion during games played with a lighter smaller ball, but locomotor activities, heart rate and overall technical-tactical game performance remained unaffected....

  10. Collapse of nonlinear Langmuir waves

    International Nuclear Information System (INIS)

    Malkin, V.M.

    1986-01-01

    The dispersion of sufficiently intensive Langmuir waves is determined by intrinsic (electron) nonlinearity. During Langmuir collapse the wave energy density required for the appearance of electron nonlinearity is attained, generally speaking, prior to the development of dissipative processes. Up to now, the effect of electron nonlinearity on the collapse dynamics and spectrum of strong Langmuir turbulence ( which may be very appreciable ) has not been studied extensively because of the difficulty of describing nonlinear Langmuir waves. In the present paper the positive determinacy of the electron nonlinear hamiltonian is proven, the increment of modulation instability of a nonlinear Langmuir wave cluster localized in a cavity is calculated, and the universal law of their collapse is found

  11. Size, but not experience, affects the ontogeny of constriction performance in ball pythons (Python regius).

    Science.gov (United States)

    Penning, David A; Dartez, Schuyler F

    2016-03-01

    Constriction is a prey-immobilization technique used by many snakes and is hypothesized to have been important to the evolution and diversification of snakes. However, very few studies have examined the factors that affect constriction performance. We investigated constriction performance in ball pythons (Python regius) by evaluating how peak constriction pressure is affected by snake size, sex, and experience. In one experiment, we tested the ontogenetic scaling of constriction performance and found that snake diameter was the only significant factor determining peak constriction pressure. The number of loops applied in a coil and its interaction with snake diameter did not significantly affect constriction performance. Constriction performance in ball pythons scaled differently than in other snakes that have been studied, and medium to large ball pythons are capable of exerting significantly higher pressures than those shown to cause circulatory arrest in prey. In a second experiment, we tested the effects of experience on constriction performance in hatchling ball pythons over 10 feeding events. By allowing snakes in one test group to gain constriction experience, and manually feeding snakes under sedation in another test group, we showed that experience did not affect constriction performance. During their final (10th) feedings, all pythons constricted similarly and with sufficiently high pressures to kill prey rapidly. At the end of the 10 feeding trials, snakes that were allowed to constrict were significantly smaller than their non-constricting counterparts. © 2016 Wiley Periodicals, Inc.

  12. THREE-DIMENSIONAL BOLTZMANN HYDRO CODE FOR CORE COLLAPSE IN MASSIVE STARS. I. SPECIAL RELATIVISTIC TREATMENTS

    International Nuclear Information System (INIS)

    Nagakura, Hiroki; Sumiyoshi, Kohsuke; Yamada, Shoichi

    2014-01-01

    We propose a novel numerical method for solving multi-dimensional, special relativistic Boltzmann equations for neutrinos coupled with hydrodynamics equations. This method is meant to be applied to simulations of core-collapse supernovae. We handle special relativity in a non-conventional way, taking account of all orders of v/c. Consistent treatment of the advection and collision terms in the Boltzmann equations has been a challenge, which we overcome by employing two different energy grids: Lagrangian remapped and laboratory fixed grids. We conduct a series of basic tests and perform a one-dimensional simulation of core-collapse, bounce, and shock-stall for a 15 M ☉ progenitor model with a minimum but essential set of microphysics. We demonstrate in the latter simulation that our new code is capable of handling all phases in core-collapse supernova. For comparison, a non-relativistic simulation is also conducted with the same code, and we show that they produce qualitatively wrong results in neutrino transfer. Finally, we discuss a possible incorporation of general relativistic effects into our method

  13. Models of collapsing and expanding anisotropic gravitating source in f(R, T) theory of gravity

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, G. [The Islamia University of Bahawalpur, Department of Mathematics, Bahawalpur (Pakistan); Ahmed, Riaz [The Islamia University of Bahawalpur, Department of Mathematics, Bahawalpur (Pakistan); University of the Central Punjab, Department of Mathematics, Lahore (Pakistan)

    2017-07-15

    In this paper, we have formulated the exact solutions of the non-static anisotropic gravitating source in f(R, T) gravity which may lead to expansion and collapse. By assuming there to be no thermal conduction in gravitating source, we have determined parametric solutions in f(R, T) gravity with a non-static spherical geometry filled using an anisotropic fluid. We have examined the ranges of the parameters for which the expansion scalar becomes negative and positive, leading to collapse and expansion, respectively. Further, using the definition of the mass function, the conditions for the trapped surface have been explored, and it has been investigated that there exists a single horizon in this case. The impact of the coupling parameter λ has been discussed in detail in both cases. For the various values of the coupling parameter λ, we have plotted the energy density, anisotropic pressure and anisotropy parameter in the cases of collapse and expansion. The physical significance of the graphs has been explained in detail. (orig.)

  14. Six collapses

    International Nuclear Information System (INIS)

    Miller, R.H.; Smith, B.F.

    1979-01-01

    The self-consistent dynamical development of six stellar systems, started from rotating spherical configurations, has been studied by means of a fully three-dimensional n-body integration. The six examples had different initial angular velocities and velocity dispersions. All settled down into prolate bars rotating about a short axis within two initial rotation periods. The bars are long-lived, robust, and stable. Bars are the natural form toward which rapidly rotating stellar dynamical systems develop, instead of the flattened axisymmetric disks that had been expected.The early stages of each collapse are reasonably well described by a theoretical model according to which a collapse passes through a sequence of rigidly rotating, uniform-density spheroids. The first significant departures from spheroidal form were axisymmetric in all cases. Rings formed in some examples, sheets in others, with transition cases between these extremes. Nonaxisymmetry forms developed from these intermediate stages

  15. The Energy Cost of Running with the Ball in Soccer.

    Science.gov (United States)

    Piras, Alessandro; Raffi, Milena; Atmatzidis, Charalampos; Merni, Franco; Di Michele, Rocco

    2017-11-01

    Running with the ball is a soccer-specific activity frequently used by players during match play and training drills. Nevertheless, the energy cost (EC) of on-grass running with the ball has not yet been determined. The purpose of this study was therefore to assess the EC of constant-speed running with the ball, and to compare it with the EC of normal running. Eight amateur soccer players performed two 6- min runs at 10 km/h on artificial turf, respectively with and without the ball. EC was measured with indirect calorimetry and, furthermore, estimated with a method based on players' accelerations measured with a GPS receiver. The EC measured with indirect calorimetry was higher in running with the ball (4.60±0.42 J/kg/m) than in normal running (4.19±0.33 J/kg/m), with a very likely moderate difference between conditions. Instead, a likely small difference was observed between conditions for EC estimated from GPS data (4.87±0.07 vs. 4.83±0.08 J/kg/m). This study sheds light on the energy expenditure of playing soccer, providing relevant data about the EC of a typical soccer-specific activity. These findings may be a reference for coaches to precisely determine the training load in drills with the ball, such as soccer-specific circuits or small-sided games. © Georg Thieme Verlag KG Stuttgart · New York.

  16. The coefficient of restitution of pressurized balls: a mechanistic model

    Science.gov (United States)

    Georgallas, Alex; Landry, Gaëtan

    2016-01-01

    Pressurized, inflated balls used in professional sports are regulated so that their behaviour upon impact can be anticipated and allow the game to have its distinctive character. However, the dynamics governing the impacts of such balls, even on stationary hard surfaces, can be extremely complex. The energy transformations, which arise from the compression of the gas within the ball and from the shear forces associated with the deformation of the wall, are examined in this paper. We develop a simple mechanistic model of the dependence of the coefficient of restitution, e, upon both the gauge pressure, P_G, of the gas and the shear modulus, G, of the wall. The model is validated using the results from a simple series of experiments using three different sports balls. The fits to the data are extremely good for P_G > 25 kPa and consistent values are obtained for the value of G for the wall material. As far as the authors can tell, this simple, mechanistic model of the pressure dependence of the coefficient of restitution is the first in the literature. *%K Coefficient of Restitution, Dynamics, Inflated Balls, Pressure, Impact Model

  17. Survival probability of a local excitation in a non-Markovian environment: Survival collapse, Zeno and anti-Zeno effects

    International Nuclear Information System (INIS)

    Rufeil-Fiori, E.; Pastawski, H.M.

    2009-01-01

    The decay dynamics of a local excitation interacting with a non-Markovian environment, modeled by a semi-infinite tight-binding chain, is exactly evaluated. We identify distinctive regimes for the dynamics. Sequentially: (i) early quadratic decay of the initial-state survival probability, up to a spreading time t S , (ii) exponential decay described by a self-consistent Fermi Golden Rule, and (iii) asymptotic behavior governed by quantum diffusion through the return processes, leading to an inverse power law decay. At this last cross-over time t R a survival collapse becomes possible. This could reduce the survival probability by several orders of magnitude. The cross-over times t S and t R allow to assess the range of applicability of the Fermi Golden Rule and give the conditions for the observation of the Zeno and anti-Zeno effect.

  18. In Vitro Antimicrobial Activity of Gel Containing the Herbal Ball Extract against Propionibacterium acnes

    Directory of Open Access Journals (Sweden)

    Chutima Jantarat

    2018-02-01

    Full Text Available The herbal ball has been used as a Thai traditional medicine for relieving many diseases including acne. However, the application process of the herbal ball in practice is complicated and time consuming. The objective of this work was to utilize an herbal ball extract to formulate a gel to reach a more favorable use of the herbal ball for acne treatment. An herbal ball consisting of Andrographis paniculata, Centella asiatica, the Benchalokawichian remedy and the stem bark powder of Hesperethusa crenulata was prepared. The obtained herbal ball was steamed and squeezed to obtain the extract. Gel formulations containing the herbal ball extract at concentrations of 0.1, 1 and 5% w/w were prepared based on a carbomer gel. The herbal ball extract had antioxidant (EC50 = 219.27 ± 36.98 μg/mL and anti Propionibacterium acnes activities (minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC = 31.25 μg/mL. The 5% w/w gel formulation had antimicrobial activity against P. acnes, showing an inhibition zone value of 10.00 ± 1.00 mm. This indicates that the developed gel formulation has potential for acne treatment. In comparison to the traditional method of herbal ball usage, the application of herbal ball extract in the form of gel should be more convenient to use.

  19. Prospective versus predictive control in timing of hitting a falling ball.

    Science.gov (United States)

    Katsumata, Hiromu; Russell, Daniel M

    2012-02-01

    Debate exists as to whether humans use prospective or predictive control to intercept an object falling under gravity (Baurès et al. in Vis Res 47:2982-2991, 2007; Zago et al. in Vis Res 48:1532-1538, 2008). Prospective control involves using continuous information to regulate action. τ, the ratio of the size of the gap to the rate of gap closure, has been proposed as the information used in guiding interceptive actions prospectively (Lee in Ecol Psychol 10:221-250, 1998). This form of control is expected to generate movement modulation, where variability decreases over the course of an action based upon more accurate timing information. In contrast, predictive control assumes that a pre-programmed movement is triggered at an appropriate criterion timing variable. For a falling object it is commonly argued that an internal model of gravitational acceleration is used to predict the motion of the object and determine movement initiation. This form of control predicts fixed duration movements initiated at consistent time-to-contact (TTC), either across conditions (constant criterion operational timing) or within conditions (variable criterion operational timing). The current study sought to test predictive and prospective control hypotheses by disrupting continuous visual information of a falling ball and examining consistency in movement initiation and duration, and evidence for movement modulation. Participants (n = 12) batted a ball dropped from three different heights (1, 1.3 and 1.5 m), under both full-vision and partial occlusion conditions. In the occlusion condition, only the initial ball drop and the final 200 ms of ball flight to the interception point could be observed. The initiation of the swing did not occur at a consistent TTC, τ, or any other timing variable across drop heights, in contrast with previous research. However, movement onset was not impacted by occluding the ball flight for 280-380 ms. This finding indicates that humans did not

  20. Microstructural and Material Quality Effects on Rolling Contact Fatigue of Highly Elastic Intermetallic Ball Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Howard, S. Adam; Thomas, Fransua; Stanford, Malcolm K.

    2016-01-01

    Rolling element bearings made from highly-elastic intermetallic materials (HIM)s, such as 60NiTi, are under development for applications that require superior corrosion and shock resistance. Compared to steel, intermetallics have been shown to have much lower rolling contact fatigue (RCF) stress capability in simplified 3-ball on rod (ASTM STP 771) fatigue tests. In the 3-ball tests, poor material quality and microstructural flaws negatively affect fatigue life but such relationships have not been established for full-scale 60NiTi bearings. In this paper, 3-ball-on-rod fatigue behavior of two quality grades of 60NiTi are compared to the fatigue life of full-scale 50mm bore ball bearings made from the same materials. 60NiTi RCF rods with material or microstructural flaws suffered from infant mortality failures at all tested stress levels while high quality 60NiTi rods exhibited no failures at lower stress levels. Similarly, tests of full-scale bearings made from flawed materials exhibited early surface fatigue and through crack type failures while bearings made from high quality material did not fail even in long-term tests. Though the full-scale bearing test data is yet preliminary, the results suggest that the simplified RCF test is a good qualitative predictor of bearing performance. These results provide guidance for materials development and to establish minimum quality levels required for successful bearing operation and life.