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Sample records for ball ball lightning

  1. Ball lightning.

    OpenAIRE

    Stenhoff, Mark

    1988-01-01

    Ball lightning is alleged by some to be a rare atmospheric phenomenon usually associated with thunderstorms, while others hold that it does not exist. This controversy has continued for centuries. This study comprises a critical evaluation of evidence for the existence of ball lightning. An historical review of the controversy is first presented, giving a chronological account of developments in ball lightning theories and of important observations alleged to be of the phenomenon. Other pheno...

  2. Science of Ball Lightning (Fire Ball)

    Science.gov (United States)

    Ohtsuki, Yoshi-Hiko

    1989-08-01

    The Table of Contents for the full book PDF is as follows: * Organizing Committee * Preface * Ball Lightning -- The Continuing Challenge * Hungarian Ball Lightning Observations in 1987 * Nature of Ball Lightning in Japan * Phenomenological and Psychological Analysis of 150 Austrian Ball Lightning Reports * Physical Problems and Physical Properties of Ball Lightning * Statistical Analysis of the Ball Lightning Properties * A Fluid-Dynamical Model for Ball Lightning and Bead Lightning * The Lifetime of Hill's Vortex * Electrical and Radiative Properties of Ball Lightning * The Candle Flame as a Model of Ball Lightning * A Model for Ball Lightning * The High-Temperature Physico-Chemical Processes in the Lightning Storm Atmosphere (A Physico-Chemical Model of Ball Lightning) * New Approach to Ball Lightning * A Calculation of Electric Field of Ball Lightning * The Physical Explanation to the UFO over Xinjiang, Northern West China * Electric Reconnection, Critical Ionization Velocity, Ponderomotive Force, and Their Applications to Triggered and Ball Lightning * The PLASMAK™ Configuration and Ball Lightning * Experimental Research on Ball Lightning * Performance of High-Voltage Test Facility Designed for Investigation of Ball Lightning * List of Participants

  3. Birth of ball lightning

    Science.gov (United States)

    Lowke, J. J.; Smith, D.; Nelson, K. E.; Crompton, R. W.; Murphy, A. B.

    2012-10-01

    Many observations of ball lightning report a ball of light, about 10 cm in diameter, moving at about walking speed, lasting up to 20 s and frequently existing inside of houses and even aeroplanes. The present paper reports detailed observations of the initiation or birth of ball lightning. In two cases, navigation crew of aircraft saw ball lightning form at the windscreen inside the cockpit of their planes. In the first case, the ball lightning occurred during a thunderstorm, with much lightning activity outside of the plane. In the second case, large "horns" of electrical corona were seen outside of the plane at the surface of the radome, just prior to the formation of the ball lightning. A third case reports ball lightning formed inside of a house, during a thunderstorm, at a closed glass window. It is proposed, based on two-dimensional calculations of electron and ion transport, that ball lightning in these cases is driven and formed by atmospheric ions impinging and collecting on the insulating surface of the glass or Perspex windows. This surface charge can produce electric fields inside of the cockpit or room sufficient to sustain an electric discharge. Charges of opposite sign to those outside of the window accumulate on the inside surface of the glass, leaving a ball of net charge moving inside of the cockpit or room to produce a pulsed discharge on a microsecond time scale.

  4. Formation of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Silberg, P.A. (2833 Lawton Drive, Amarillo, Texas (USA))

    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 under 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.

  5. Ball lightning burn.

    Science.gov (United States)

    Selvaggi, Gennaro; Monstrey, Stan; von Heimburg, Dennis; Hamdi, Mustapha; Van Landuyt, Koen; Blondeel, Phillip

    2003-05-01

    Ball lightning is a rare physical phenomenon, which is not yet completely explained. It is similar to lightning but with different, peculiar characteristics. It can be considered a mix of fire and electricity, concentrated in a fireball with a diameter of 20-cm that most commonly appears suddenly, even in indoor conditions, during a thunderstorm. It moves quickly for several meters, can change direction, and ultimately disappears. During a great storm, a 28-year-old man and his 5-year-old daughter sustained burn wounds after ball lightning came from the outdoors through a chimney. These two patients demonstrated signs of fire and electrical injuries. The father, who lost consciousness, sustained superficial second-degree burn wounds bilaterally on the zygomatic area and deep second-degree burn wounds on his right hand (total body surface area, 4%). His daughter demonstrated superficial second-degree burn wounds on the left part of the face and deep second-degree and third-degree burn wounds (total body surface area, 30%) on the left neck, both upper arms, and the back. In this article, the authors report the first two cases of burn injuries resulting from ball lightning contact indoors. The literature on this rare phenomenon is reviewed to elucidate the nature of ball lightning. Emphasis is placed on the nature of injuries after ball lightning contact, the therapy used, and the long-term complications.

  6. Laboratory demonstration of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, Anton I; Stepanov, Sergei I; Shabanov, Gennadii D [B.P. Konstantinov St. Petersburg Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina, Leningrad region, Rusian Federation (Russian Federation)

    2004-01-31

    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)

  7. Ball Lightning Investigations

    Science.gov (United States)

    Bychkov, V. L.; Nikitin, A. I.; Dijkhuis, G. C.

    Ball lightning (BL) researches' review and theoretical models of three different authors are presented. The general review covers investigations from 1838 until the present day, and includes a discussion on observation data, experimental modeling, and theoretical approaches. Section 6.1 is written by Bychkov and Nikitin; authors of the sections 6.2, 6.3 and 6.4 are, respectively, Bychkov, Nikitin and Dijkhuis.

  8. Eddy Current Model of Ball Lightning

    OpenAIRE

    Shelton, J. D.

    2011-01-01

    Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.

  9. Plasma theory of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Ostapenko, V.I.; Tolpygo, K.B.

    1984-02-01

    The high-energy density inside the ball lightning is due to existence of intense plasma oscillations and high kinetic and potential energy of electron gas which form a pulsating ball vibrating relative to the nearly stationary ionic ball. At sublight velocities of electrons one can neglect the processes of their scattering and recombination. One obtains a relation between parameters of the plasma ball from the condition of equality of excess pressure of ions and that of Madelung forces. The high lifetime of the ball lighting is connected with small Landau damping for the longest wave vibrations.

  10. Unsolved Mystery of Ball Lightning

    Science.gov (United States)

    Bychkov, V. L.

    Ball lightning is an unusual phenomenon always drawing attention of people. There are still questions about its origination, features, interaction with environment, and phenomena related to it. On a way of studying this phenomenon, there are a lot of difficulties, the basic of them is insufficiency of authentic, scientific data. The chapter sets as the purpose to interest the reader in the problem, to describe conditions of ball lightning occurrence, theories, and its hypotheses explanation, to include readers in a circle of experimental searches in creation of a ball lightning and its analogues, and to describe fascination of a problem and difficulty of its solution.

  11. SECRET OF A BALL LIGHTNING

    Directory of Open Access Journals (Sweden)

    E.V. Savich

    2013-04-01

    Full Text Available A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming, in the end, the surrounding air into a steam cloud that transits into ferroelectric state under the magnetic field action.

  12. Structure of laboratory ball lightning

    Science.gov (United States)

    Ito, Tsuyohito; Tamura, Tomoya; Cappelli, Mark A.; Hamaguchi, Satoshi

    2009-12-01

    Trajectories of self-sustained laboratory ball lightning, generated by arc discharges with silicon, are investigated for understanding the possibility of buoyant flight. Extremely low apparent densities are found, nearly approaching that of standard air. The freely buoyant balls are observed to survive for about 0.1 s, with significantly buoyant balls surviving for several seconds. These ball lightning objects are found to have a density and size that can easily allow them to be carried by a gentle breeze of a few meters per second. The results are interpreted by a model that is an extension of that first proposed by Abrahamson and Dinniss [J. Abrahamson and J. Dinniss, Nature (London) 403, 519 (2000)]. The buoyant behavior of ball lightning seen in our experiments is believed to arise as a result of the formation of a nanoparticle oxide network growing from a molten silicon core.

  13. Ball lightning risk to aircraft

    Science.gov (United States)

    Doe, R.; Keul, A.

    2009-04-01

    Lightning is a rare but regular phenomenon for air traffic. Aircraft are designed to withstand lightning strikes. Research on lightning and aircraft can be called detailed and effective. In the last 57 years, 18 reported lightning aviation disasters with a fatality figure of at least 714 persons occurred. For comparison, the last JACDEC ten-year average fatality figure was 857. The majority encountered lightning in the climb, descent, approach and/or landing phase. Ball lightning, a metastable, rare lightning type, is also seen from and even within aircraft, but former research only reported individual incidents and did not generate a more detailed picture to ascertain whether it constitutes a significant threat to passenger and aircraft safety. Lacking established incident report channels, observations were often only passed on as "air-travel lore". In an effort to change this unsatisfactory condition, the authors have collected a first international dataset of 38 documented ball lightning aircraft incidents from 1938 to 2001 involving 13 reports over Europe, 13 over USA/Canada, and 7 over Russia. 18 (47%) reported ball lightning outside the aircraft, 18 (47%) inside, 2 cases lacked data. 8 objects caused minor damage, 8 major damage (total: 42%), only one a crash. No damage was reported in 18 cases. 3 objects caused minor crew injury. In most cases, ball lightning lasted several seconds. 11 (29%) incidents ended with an explosion of the object. A cloud-aircraft lightning flash was seen in only 9 cases (24%) of the data set. From the detailed accounts of air personnel in the last 70 years, it is evident that ball lightning is rarely, but consistently observed in connection with aircraft and can also occur inside the airframe. Reports often came from multiple professional witnesses and in several cases, damages were investigated by civil or military authorities. Although ball lightning is no main air traffic risk, the authors suggest that incident and accident

  14. Physical nature of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Stakhanov, I.P.

    1979-01-01

    An analysis is made of results obtained from the observations of ball lightning. Principal attention is given to data obtained during the last two decades. A brief critique is also offered on hypotheses about its origin. A more detailed presentation is made of the cluster hypothesis according to which ball lightning consists of complex compounds of ions and neutral molecules. The book is intended for a broad spectrum of readers, but is particularly directed toward those with a knowledge of physics and chemistry. 70 references, 24 figures, 17 tables.

  15. Generation of Laboratory Ball Lightning

    Energy Technology Data Exchange (ETDEWEB)

    Oreshko, A G [Moscow Aviation Institute (State Technical University), Volokolamskoe shosse 4, 125871 Moscow (Russian Federation)

    2006-07-15

    The phenomenon of energy conversion in the streams of directed electrons and ions into electromagnetic radiation was found out experimentally and proved theoretically. The direct proofs of the domain mechanism of the charged particles acceleration and mechanism of ball lightning generation were obtained and the theoretical calculations were refined.

  16. A Conjecture Concerning Ball Lightning

    OpenAIRE

    Sturrock, P. A.

    2016-01-01

    There is at present no theory that can explain the curious properties of ball lightning. This suggests that we may not be using the most appropriate concepts. The concept of a 'parallel space' may point the way to a valid theory.

  17. Laboratory-produced ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1994-05-01

    For 25 years I have actively been searching for the true nature of ball lightning and attempting to reproduce it at will in the laboratory. As one might expect, many unidentified lights in the atmosphere have been called ball lightning, including Texas Maffa lights (automobile headlights), flying saucers (UFOs), swamp gas in Ann Arbor, Michigan, etc. For 15 years I thought ball lightning was strictly a high-voltage phenomenon. It was not until 1984 when I was short-circuiting the electrical output of a diesel electric railroad locomotive that I realized that the phenomenon was related more to a high current. Although I am hoping for some other types of ball lightning to emerge such as strictly electrostatic-electromagnetic manifestations, I have been unlucky in finding laboratory provable evidence. Cavity-formed plasmodes can be made by putting a 2-inch burning candle in a home kitchen microwave oven. The plasmodes float around for as long as the microwave energy is present.

  18. Polymer-composite ball lightning.

    Science.gov (United States)

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads.

  19. How to create ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1991-01-01

    Procedures are given on how to produce ball lightning. Necessary equipment includes a transformer of 150,000 watts capable of providing approximately 10,000 amperes at 15 volts, 60 cycles; thick one inch cables of stranded wire leading into a 3 by 4 by 1 foot plastic tank; a quarter inch thick 4 by 6 inch aluminum plate to be used as one of the discharge electrodes; and another electrode of heavy copper wire with the insulation stripped back 6 inches.

  20. Electric charge of a lightning ball

    Science.gov (United States)

    Grigor'ev, A. I.; Shiryaeva, S. O.; Petrushov, N. A.

    2016-09-01

    The electric charge of a lightning ball is found by comparing the electrohydrodynamic stabilities of a charged drop in an electrostatic suspension and a lightning ball floating in a superposition of the gravitational field and the surface electric field. It has been assumed that the electric field strength at the surface is limited by a breakdown value. For a lightning ball radius of 15 cm, its charge is estimated as several microcoulombs. Accordingly, the density of electrostatic energy accumulated in the lightning ball is on the order of one-hundredth of a joule per square centimeter. The density of the material that constitutes the lightning ball has been estimated for the case when the electric field strength at the site of its origination is several times higher than that in fine weather. The density of the lightning ball turns out to differ from that of air by only a few percents.

  1. Phenomenon of ball lightning and its outgrowths

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)]. E-mail: v_torchigin@mail.ru; Torchigin, A.V. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)

    2005-03-28

    New physical phenomena deduced from properties of ball lightning are considered under assumption that ball lightning is a light bubble comprising of a thin spherical layer of compressed air where an intense light circulates in all possible directions. Explanation of behavior of autonomous luminous objects produced at gas discharge is presented.

  2. A model for ball lightning

    International Nuclear Information System (INIS)

    Fryberger, D.

    1994-10-01

    A model for ball lightning (BL) is described. It is based upon the vorton model for elementary particles, which exploits the symmetry between electricity and magnetism. The core, or driving engine, of BL in this model is comprised of a vorton-antivorton plasma. The energy of BL, which derives from nucleon decay catalyzed by this plasma, leads, through various mechanisms, to BL luminosity as well as to other BL features. It is argued that this model could also be a suitable explanation for other luminous phenomena, such as the unidentified atmospheric light phenomena seen at Hessdalen. It is predicted that BL and similar atmospheric luminous phenomena should manifest certain features unique to this model, which would be observable with suitable instrumentation

  3. Relativistic-microwave theory of ball lightning

    Science.gov (United States)

    Wu, H.-C.

    2016-06-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  4. Relativistic-microwave theory of ball lightning.

    Science.gov (United States)

    Wu, H-C

    2016-06-22

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  5. Secret of a ball lightning

    OpenAIRE

    Савич, Эдуард Владимирович

    2013-01-01

    Шаровая молния – явление природы, происходящее при ударе линейной молнии с ее воздействием тепловой и магнитной энергии, возникающей вокруг канала линейной молнии и в результате образующей из окружающего воздуха облако пара, переходящего под воздействием магнитного поля сегнетоэлектрическое состояние. A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming...

  6. Energy transfer problems of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egely, G.

    1986-04-01

    The paper analyzes the energy transport phenomenon of ball lightnings, but momentum and charge transport phenomena are considered as well. The physical properties as energy density and transfer are investigated using several observers' accounts of interactions with different objects. It is shown that contrary to previous assumptions the ball lightning has negative electric charge, and very high internal energy density. Both internal and external energy source models are analyzed, and it is shown that regardless to the details of a given model neither of them can explain actual observations. This has been validated by a well documented case study, and by several additional observations. An entirely new, testable model is suggested, which is able to stand for all observed properties of ball lightnings, and it explains the cause of rarity of ball lightnings, and the reasons of the unsuccessful experimental efforts. It is shown that the plasma sphere is just a visible side effect of a more important phenomenon.

  7. Relativistic-microwave theory of ball lightning

    OpenAIRE

    H.-C. Wu

    2016-01-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by partic...

  8. Electrostatic charge bounds for ball lightning models

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Karl D [Department of Technology, Texas State University, San Marcos, TX 78666 (United States)], E-mail: kdstephan@txstate.edu

    2008-03-15

    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. Electrostatic charge bounds for ball lightning models

    Science.gov (United States)

    Stephan, Karl D.

    2008-03-01

    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.

  10. On the energy characteristics of ball lightning.

    Science.gov (United States)

    Bychkov, A V; Bychkov, V L; Abrahamson, John

    2002-01-15

    A compilation of 17 observations of ball lightning showing the most energetic effects is presented along with estimates of their energy content. These observations were chosen from several thousand for the much stronger interaction of each ball lightning on its surroundings, and the method of energy estimation outlined. The case is put that some of the observations show a higher energy than self-contained chemical energy could provide. Comments have been added to the paper, arguing that the energy estimations themselves should be consistent with whatever model is used for ball lightning. For example, the presence of reacting nanoparticles releasing chemical energy may bring about the same observed effects with lower estimated energy.

  11. Interrelation between ball lightning and optically induced forces

    Science.gov (United States)

    Torchigin, V. P.; Torchigin, A. V.

    2013-09-01

    Optically induced forces are considered as a key factor for explaining the phenomenon of ball lightning. They can provide not only the existence of ball lightning in the form of self-confined intense white light circulating in a spherical shell of air strongly compressed by the light but also the anomalous motion of ball lightning in the terrestrial atmosphere.

  12. Burning molten metallic spheres: One class of ball lightning?

    Science.gov (United States)

    Stephan, Karl D.; Massey, Nathan

    2008-08-01

    Abrahamson and Dinniss [2000. Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil. Nature 403, 519-521] proposed a theory of ball lighting in which silicon nanoparticles undergo slow oxidation and emit light. Paiva et al. [2007. Production of ball-lightning-like luminous balls by electrical discharges in silicon. Physical Review Letters 98, 048501] reported that an electric arc to silicon produced long-lasting luminous white spheres showing many characteristics of ball lightning. We show experimentally that these consist of burning molten silicon spheres with diameters in the 0.1-1 mm range. The evidence of our experiments leads us to propose that a subset of ball lightning events may consist of macro-scale molten spheres of burning metallic materials likely to be ejected from a conventional lightning strike to earth.

  13. Production of Ball-Lightning-Like Luminous Balls by Electrical Discharges in Silicon

    Science.gov (United States)

    Paiva, Gerson Silva; Pavão, Antonio Carlos; Alpes de Vasconcelos, Elder; Mendes, Odim, Jr.; Felisberto da Silva, Eronides, Jr.

    2007-01-01

    We performed electric arc discharges in pure Si to generate luminous balls with lifetime in the order of seconds and several properties usually reported for natural ball lightning. This simple experiment does not rely on energy sources and excitation mechanisms that are improbable in the natural phenomenon and clearly demonstrates the role of vaporization and oxidation of Si, as proposed by the Abrahamson-Dinniss theory for ball-lightning formation.

  14. Production of ball-lightning-like luminous balls by electrical discharges in silicon.

    Science.gov (United States)

    Paiva, Gerson Silva; Pavão, Antonio Carlos; Alpes de Vasconcelos, Elder; Mendes, Odim; da Silva, Eronides Felisberto

    2007-01-26

    We performed electric arc discharges in pure Si to generate luminous balls with lifetime in the order of seconds and several properties usually reported for natural ball lightning. This simple experiment does not rely on energy sources and excitation mechanisms that are improbable in the natural phenomenon and clearly demonstrates the role of vaporization and oxidation of Si, as proposed by the Abrahamson-Dinniss theory for ball-lightning formation.

  15. Spherical microwave confinement and ball lightning

    Science.gov (United States)

    Robinson, William Richard

    This dissertation presents the results of research done on unconventional energy technologies from 1995 to 2009. The present civilization depends on an infrastructure that was constructed and is maintained almost entirely using concentrated fuels and ores, both of which will run out. Diffuse renewable energy sources rely on this same infrastructure, and hence face the same limitations. I first examined sonoluminescence directed toward fusion, but demonstrated theoretically that this is impossible. I next studied Low Energy Nuclear Reactions and developed methods for improving results, although these have not been implemented. In 2000, I began Spherical Microwave Confinement (SMC), which confines and heats plasma with microwaves in a spherical chamber. The reactor was designed and built to provide the data needed to investigate the possibility of achieving fusion conditions with microwave confinement. A second objective was to attempt to create ball lightning (BL). The reactor featured 20 magnetrons, which were driven by a capacitor bank and operated in a 0.2 s pulse mode at 2.45 GHz. These provided 20 kW to an icosahedral array of 20 antennas. Video of plasmas led to a redesign of the antennas to provide better coupling of the microwaves to the plasma. A second improvement was a grid at the base of the antennas, which provided corona electrons and an electric field to aid quick formation of plasmas. Although fusion conditions were never achieved and ball lightning not observed, experience gained from operating this basic, affordable system has been incorporated in a more sophisticated reactor design intended for future research. This would use magnets that were originally planned. The cusp geometry of the magnetic fields is suitable for electron cyclotron resonance in the same type of closed surface that in existing reactors has generated high-temperature plasmas. Should ball lightning be created, it could be a practical power source with nearly ideal

  16. Attempts to create ball lightning with triggered lightning

    Science.gov (United States)

    Hill, Jonathan D.; Uman, Martin A.; Stapleton, Michael; Jordan, Douglas M.; Chebaro, Alexander M.; Biagi, Christopher J.

    2010-08-01

    We describe attempts to create ball lightning by directing lightning, triggered from natural thunderclouds using the rocket-and-wire technique, through a variety of materials. Some of the observed phenomena have features in common with natural ball lightning or with laboratory attempts to create it: flame-like luminosity for up to 0.5 s above salt water; constant-luminosity silicon fragments falling for about 1 s under the influence of gravity; a 0.7 m region of stationary luminosity whose bottom was 0.3 m above a stainless steel surface to which arcing had occurred; and a glow for about 0.5 s above pine tree sections.

  17. A proposed experiment on ball lightning model

    Energy Technology Data Exchange (ETDEWEB)

    Ignatovich, Vladimir K., E-mail: v.ignatovi@gmail.com [Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Ignatovich, Filipp V. [1565 Jefferson Rd., 420, Rochester, NY 14623 (United States)

    2011-09-19

    Highlights: → We propose to put a glass sphere inside an excited gas. → Then to put a light ray inside the glass in a whispering gallery mode. → If the light is resonant to gas excitation, it will be amplified at every reflection. → In ms time the light in the glass will be amplified, and will melt the glass. → A liquid shell kept integer by electrostriction forces is the ball lightning model. -- Abstract: We propose an experiment for strong light amplification at multiple total reflections from active gaseous media.

  18. Are Perytons Signatures of Ball Lightning?

    Science.gov (United States)

    Dodin, I. Y.; Fisch, N. J.

    2014-10-01

    The enigmatic downchirped signals, called "perytons," that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures may be discarding events that have the same nature as known perytons.

  19. Ball lightning observation: an objective video-camera analysis report

    OpenAIRE

    Sello, Stefano; Viviani, Paolo; Paganini, Enrico

    2011-01-01

    In this paper we describe a video-camera recording of a (probable) ball lightning event and both the related image and signal analyses for its photometric and dynamical characterization. The results strongly support the BL nature of the recorded luminous ball object and allow the researchers to have an objective and unique video document of a possible BL event for further analyses. Some general evaluations of the obtained results considering the proposed ball lightning models conclude the paper.

  20. 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.

  1. Are perytons signatures of ball lightning?

    Energy Technology Data Exchange (ETDEWEB)

    Dodin, I. Y.; Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08543 (United States)

    2014-10-20

    The enigmatic downchirped signals, called 'perytons', that are detected by radio telescopes in the GHz frequency range may be produced by an atmospheric phenomenon known as ball lightning (BL). If BLs act as nonstationary radio frequency cavities, their characteristic emission frequencies and evolution timescales are consistent with peryton observations, and so are general patterns in which BLs are known to occur. Based on this evidence, testable predictions are made that can confirm or rule out a causal connection between perytons and BLs. In either case, how perytons are searched for in observational data may warrant reconsideration because existing procedures may be discarding events that have the same nature as known perytons.

  2. Ball lightning with the nonrelativistic electrons of the core

    Science.gov (United States)

    Shmatov, M. L.

    2015-08-01

    The lifetimes, volume densities of energy, electron and ion densities and other parameters of ball lightning cores with the nonrelativistic electrons are estimated. The model according to which the motion of the electrons of the ball lightning core is the superposition of the oscillatory motion and the thermal motion in the directions perpendicular to those of the oscillations is proposed. Some problems related to isolation of the ball lightning core from the atmosphere and the transfer of the atmospheric pressure on it are considered.

  3. Sources and components of ball lightning theory

    Science.gov (United States)

    Nikitin, A. I.; Bychkov, V. L.; Nikitina, T. F.; Velichko, A. M.; Abakumov, V. I.

    2018-03-01

    The article describes the cases when ball lightning (BL) exhibited an extremely high specific energy store (up to 1010 J/m3), a presence of uncompensated electric charge (up to 10‑3 C) and an ability to generate high frequency pulses (up to 10 MW). It is shown that the realization of a combination of these properties of BL is possible if to consider it as a heterogeneous system consisting of a unipolarly charged core and a dielectric shell. In the electric field of the core charge, arises a force owing to the polarization of the shell that opposes the Coulomb repulsion force of the charges. BL models constructed according to the indicated principle are described: the electrodynamic model and the chemical-thermal model, which treats BL as a hollow sphere filled with steam. The requirement to take into account the main three properties of BL makes it possible to reduce the number of models of this natural phenomenon. Detailed cases of observations of high-energy lightning are analyzed.

  4. The Riddle of Ball Lightning: A Review

    Directory of Open Access Journals (Sweden)

    José Donoso

    2006-01-01

    Full Text Available One of the most intriguing and enduring scientific challenges is to find an explanation for ball lightning, the shining fireballs that sometimes appear near lightning strokes. Although many theoretical ideas have been proposed and much experimental work has been performed, there is not yet an accepted explanation of their amazing properties. They are surprisingly stable, lasting up to 10 s, even minutes in some rare cases. By night, their appearance can be spectacular, but their brilliance is just similar to that of a home electric bulb. Most of the time, their motion is smooth and horizontal, but it can also be erratic and chaotic; they can penetrate indoors through window panes. We review here some of the most discussed approaches, including both theoretical models to find an explanation as well as experimental efforts to reproduce them in the laboratory. We distinguish between chemical and physical models, depending on whether their stability is mainly based on their chemical composition or on purely physical phenomena involving electromagnetic fields and plasmas.

  5. Analysis of Conditions favorable for Ball Lightning Creation

    OpenAIRE

    Boerner, H.

    2016-01-01

    This report uses a few well documented cases of Ball Lightning (or BL for short) observations to demonstrate a correlation between BL and positive lightning, especially strong positive lightning. This allows to draw conclusions and predictions about future BL observations and the pro- duction of these objects in the laboratory. Contrary to many current BL theories, these objects can be created without direct contact to a lightning channel. Very high electric fields appear to be essential for ...

  6. The fragmented science of ball lightning (with comment).

    Science.gov (United States)

    Turner, D J

    2002-01-15

    All the apparent anomalies in ball lightning behaviour seem to result from electrochemical processes which arise at the surface of a wet air plasma. The structure and stability of an established lightning ball are maintained by these processes and the ball operates as a thermochemical heat pump powered by the electric field of a thunderstorm. Movements result from asymmetries in the various fields which control the structure. In addition to electric, electromagnetic and gravitational fields, temperature, pressure and compositional gradients can be involved. Electrochemistry provides a framework within which specific properties can be considered using better developed or more appropriate disciplines. Several commonly made assumptions and approximations are identified which can be invalid under the specific conditions which favour ball lightning stability. If any of these limitations is ignored, seriously misleading conclusions may result. The range of power associated with lightning balls is ill defined but may vary continuously between that of globes which lack a bright centre and that of normal lightning. Our failure to contain plasmas electrochemically for more than a few seconds probably reflects our inability to balance (or even measure) the various fields which govern a ball's stability. All the fields may need to be controlled before electrochemistry can usefully be employed to contain plasmas.

  7. Energy density calculations for ball-lightning-like luminous silicon balls

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Gerson S; Ferreira, Joacy V; Bastos, Cristiano C; Dos Santos, Marcus V; Pavao, Antonio C [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Pernambuco (Brazil)

    2010-05-11

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m{sup -3}, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model. (methodological notes)

  8. METHODOLOGICAL NOTES: Energy density calculations for ball-lightning-like luminous silicon balls

    Science.gov (United States)

    Paiva, Gerson S.; Ferreira, Joacy V.; Bastos, Cristiano C.; dos Santos, Marcus V.; Pavão, Antonio C.

    2010-05-01

    The energy density of a luminous silicon ball [Phys. Rev. Lett. 98 048501 (2007)] is calculated for a model with a metal core surrounded by an atmosphere of silicon oxides. Experimental data combined with the molecular orbital calculations of the oxidation enthalpy lead to a mean energy density of 3.9 MJ m-3, which is within the range of estimates from other ball lightning models. This result provides good evidence to support the silicon-based model.

  9. Ball lightning from a water beaker; Kugelblitze aus dem Wasserbecher

    Energy Technology Data Exchange (ETDEWEB)

    Buehrke, T.

    2008-07-01

    The very existence of these balls of light is the subject of controversy. People who have seen them say they can move along power lines and even go through window panes. Until recently, there was no way to get closer to ball lightning by scientific means. But now, GERD FUSSMANN from the MAX PLANCK INSTITUTE FOR PLASMA PHYSICS and BERLIN'S HUMBOLDT UNIVERSITY has managed to create blazing balls of plasma in his lab - and they may just help explain the phenomenon. (orig.)

  10. Study on the luminous characteristics of a natural ball lightning

    Science.gov (United States)

    Wang, Hao; Yuan, Ping; Cen, Jianyong; Liu, Guorong

    2018-02-01

    According to the optical images of the whole process of a natural ball lightning recorded by two slit-less spectrographs in the Qinghai plateau of China, the simulated observation experiment on the luminous intensity of the spherical light source was carried out. The luminous intensity and the optical power of the natural ball lightning in the wavelength range of 400-690 nm were estimated based on the experimental data and the Lambert-Beer Law. The results show that the maximum luminous intensity was about 1.24 × 105 cd in the initial stage of the natural ball lightning, and the maximum luminous intensity and the maximum optical power in most time of its life were about 5.9 × 104 cd and 4.2 × 103 W, respectively.

  11. Evidence of microscopic ball lightning in cold fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, E.H. [PO Box 2013, Champaign, IL 61825 (United States)

    2006-07-01

    There is evidence of microscopic ball lightning in several methods of cold fusion and transmutation. Thus far the experiments of Matsumoto, Miley, Shoulders, Savvatimova, and Urutskoev et al. have shown evidence of these objects that range in size from sub-atomic to about 1 mm in diameter. This article presents pictures and evidence collected by these groups, summarizes the evidence found by other groups, and discusses the significance of microscopic ball lightning. The implications for atomic physics and physics in general are discussed. (author)

  12. Ball lightning dynamics and stability at moderate ion densities

    Science.gov (United States)

    Morrow, R.

    2017-10-01

    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 µs their influence on the ion dynamics is negligible. Further development after 1 µs 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. James L. Tuck Los Alamos ball lightning pioneer

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D.A.

    1999-07-01

    James Tuck was well known for starting the Project Sherwood group at Los Alamos Scientific Laboratory in 1952. This group was formed to study and develop concepts for controlled fusion energy. In his later years after retiring from Controlled Fusion Division, he continued research at Los Alamos on the topic of ball lightning. He traveled widely giving lectures on both observations of others and his own experimental efforts. He collected anecdotal observations obtained from those in his lecture audiences during his travels and from responses from newspaper articles where he asked for specific information from ball lightning observers. He finally cut off this collection of data when the number of responses became overwhelming. The author's primary publication on ball lightning was a short laboratory report. He planned on publishing a book on the subject but this was never completed before his death. Tuck focused his experimental effort on attempting to duplicate the production of plasma balls claimed to be observed in US Navy submarines when a switch was opened under overload conditions with battery power. During lunch breaks he made use of a Los Alamos N-division battery bank facility to mock up a submarine power pack and switch gear. This non-funded effort was abruptly terminated when an explosion occurred in the facility. An overview of Tuck's research and views will be given. The flavor Jim's personality as well as a ball produced with his experimental apparatus will be shown using video chips.

  14. Observation of the Optical and Spectral Characteristics of Ball Lightning

    Science.gov (United States)

    Cen, Jianyong; Yuan, Ping; Xue, Simin

    2014-01-01

    Ball lightning (BL) has been observed with two slitless spectrographs at a distance of 0.9 km. The BL is generated by a cloud-to-ground lightning strike. It moves horizontally during the luminous duration. The evolution of size, color, and light intensity is reported in detail. The spectral analysis indicates that the radiation from soil elements is present for the entire lifetime of the BL.

  15. Ball lightning as a force-free magnetic knot

    Science.gov (United States)

    Ranada; Soler; Trueba

    2000-11-01

    The stability of fireballs in a recent model of ball lightning is studied. It is shown that the balls shine while relaxing in an almost quiescent expansion, and that three effects contribute to their stability: (i) the formation in each one during a process of Taylor relaxation of a force-free magnetic field, a concept introduced in 1954 in order to explain the existence of large magnetic fields and currents in stable configurations of astrophysical plasmas; (ii) the so called Alfven conditions in magnetohydrodynamics; and (iii) the approximate conservation of the helicity integral. The force-free fields that appear are termed "knots" because their magnetic lines are closed and linked.

  16. Extension of Relativistic-Microwave Theory of Ball Lightning Including Long-term Losses And Stability

    OpenAIRE

    Stephan, Karl D.

    2016-01-01

    After centuries, the long-standing problem of the nature of ball lightning may be closer to a solution. The relativistic-microwave theory of ball lightning recently proposed by Wu accounts for many of the leading characteristics of ball lightning, which most previous theories have failed to do. It involves the impact of a lightning-caused relativistic electron bunch to soil, producing an EM pulse that forms a plasma bubble. While the theory presents a plausible account of ball-lightning forma...

  17. AN EXPERIMENTAL INVESTIGATION OF NEGATIVE POINT-PLANE CORONA AND ITS RELATION TO BALL LIGHTNING

    Science.gov (United States)

    Existing theories of ball lightning are briefly discussed. the corona discharge from a negative point flows in a series of regular pulses called...trichel pulses. based on the theoretical relationship between corona discharge (trichel pulses) and ball lightning , an experimental program is developed...pulse-repetition frequencies of a few mc/s have been the highest attained in the course of the experiments. the results obtained are then discussed as they concern ball lightning .

  18. 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.

  19. Investigation of polymer ball lightning objects in atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Bychkov, V.L. [Inst. for High Temperature, Moscow (Russian Federation); Klimov, A.I. [Moscow Radiotechnical Inst. (Russian Federation)

    1995-12-31

    The generation and evolution of power intensive Ball Lightning Objects (BLO) or polymer plasmoids in air were investigated. The experimental arrangement consisted of electric discharge gun (EDG), capacitor storage with energy stored up to 5.6 kJ, electron trigger, limiting inductance 100-1000 {mu}H. EDG represented cone discharge tube 5 cm length, with cone opening 30-120{degrees}. Inner wall was covered by candle wax. Diameter of tube outlet was 10-30 mm. Time of pulse was about 30 ms, its amplitude was not higher than 60 A.

  20. Possible scenarios for the initial acceleration of electrons of the core of ball lightning

    Science.gov (United States)

    Shmatov, M. L.

    2015-12-01

    > A model for the initial acceleration of electrons of the core of ball lightning is presented, according to which this acceleration occurs on screening of the strong electric field of the positive charge injected into the atmosphere. Several scenarios for such injection, the factors favourable for the formation of ball lightning and possible experiments on such formation are considered.

  1. Radio spectrum measurements of artificial ball lightning and testing the hypothesis on its plasmochemical nature

    Science.gov (United States)

    Kopeikin, V. V.

    2014-01-01

    Spectral measurements of radiowaves emitted by artificial ball lightning are presented. The measurements were carried out using two different facilities: a pulsed power generator (PPG) and a three-contour Tesla transformer. The results of these measurements confirm the hypothesis that ball lightning is a self-oscillator of high-voltage pulses in the radio range.

  2. Force-free field model of ball lightning

    Science.gov (United States)

    Tsui, K. H.

    2001-03-01

    Due to the nature that the force-free magnetic field, whose current carried by the conducting plasma is everywhere parallel to the magnetic field it generates, is the minimum energy configuration under the constraint of magnetic helicity conservation, ball lightning is considered as a self-organized phenomenon with a plasma fireball immersed in a spherical force-free magnetic field. Since this field does not exert force on the plasma, the plasma pressure, by itself, is in equilibrium with the surrounding environment, and the force-free magnetic field can take on any value without affecting the plasma. Due to this second feature, singular solutions of the magnetic field that are otherwise excluded are allowed, which enable a large amount of energy to be stored to sustain the ball lightning. The singularity is truncated only by the physical limit of current density that a plasma can carry. Scaling the customary soccer-size fireball to larger dimensions could account for day and night sightings of luminous objects in the sky.

  3. Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil

    Science.gov (United States)

    Abrahamson; Dinniss

    2000-02-03

    Observations of ball lightning have been reported for centuries, but the origin of this phenomenon remains an enigma. The 'average' ball lightning appears as a sphere with a diameter of 300 mm, a lifetime of about 10 s, and a luminosity similar to a 100-W lamp. It floats freely in the air, and ends either in an explosion, or by simply fading from view. It almost invariably occurs during stormy weather. Several energy sources have been proposed to explain the light, but none of these models has succeeded in explaining all of the observed characteristics. Here we report a model that potentially accounts for all of those properties, and which has some experimental support. When normal lightning strikes soil, chemical energy is stored in nanoparticles of Si, SiO or SiC, which are ejected into the air as a filamentary network. As the particles are slowly oxidized in air, the stored energy is released as heat and light. We investigated this basic process by exposing soil samples to a lightning-like discharge, which produced chain aggregates of nanoparticles: these particles oxidize at a rate appropriate for explaining the lifetime of ball lightning.

  4. Possible precursors of ball lightning. Observation of closed loops in high voltage discharges

    Energy Technology Data Exchange (ETDEWEB)

    Alexeff, I.; Rader, M. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-05-01

    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.

  5. Solid charged-core model of ball lightning

    Directory of Open Access Journals (Sweden)

    D. B. Muldrew

    2010-01-01

    Full Text Available In this study, ball lightning (BL is assumed to have a solid, positively-charged core. According to this underlying assumption, the core is surrounded by a thin electron layer with a charge nearly equal in magnitude to that of the core. A vacuum exists between the core and the electron layer containing an intense electromagnetic (EM field which is reflected and guided by the electron layer. The microwave EM field applies a ponderomotive force (radiation pressure to the electrons preventing them from falling into the core. The energetic electrons ionize the air next to the electron layer forming a neutral plasma layer. The electric-field distributions and their associated frequencies in the ball are determined by applying boundary conditions to a differential equation given by Stratton (1941. It is then shown that the electron and plasma layers are sufficiently thick and dense to completely trap and guide the EM field. This model of BL is exceptional in that it can explain all or nearly all of the peculiar characteristics of BL. The ES energy associated with the core charge can be extremely large which can explain the observations that occasionally BL contains enormous energy. The mass of the core prevents the BL from rising like a helium-filled balloon – a problem with most plasma and burning-gas models. The positively charged core keeps the negatively charged electron layer from diffusing away, i.e. it holds the ball together; other models do not have a mechanism to do this. The high electrical charges on the core and in the electron layer explains why some people have been electrocuted by BL. Experiments indicate that BL radiates microwaves upon exploding and this is consistent with the model. The fact that this novel model of BL can explain these and other observations is strong evidence that the model should be taken seriously.

  6. Solid charged-core model of ball lightning

    Science.gov (United States)

    Muldrew, D. B.

    2010-01-01

    In this study, ball lightning (BL) is assumed to have a solid, positively-charged core. According to this underlying assumption, the core is surrounded by a thin electron layer with a charge nearly equal in magnitude to that of the core. A vacuum exists between the core and the electron layer containing an intense electromagnetic (EM) field which is reflected and guided by the electron layer. The microwave EM field applies a ponderomotive force (radiation pressure) to the electrons preventing them from falling into the core. The energetic electrons ionize the air next to the electron layer forming a neutral plasma layer. The electric-field distributions and their associated frequencies in the ball are determined by applying boundary conditions to a differential equation given by Stratton (1941). It is then shown that the electron and plasma layers are sufficiently thick and dense to completely trap and guide the EM field. This model of BL is exceptional in that it can explain all or nearly all of the peculiar characteristics of BL. The ES energy associated with the core charge can be extremely large which can explain the observations that occasionally BL contains enormous energy. The mass of the core prevents the BL from rising like a helium-filled balloon - a problem with most plasma and burning-gas models. The positively charged core keeps the negatively charged electron layer from diffusing away, i.e. it holds the ball together; other models do not have a mechanism to do this. The high electrical charges on the core and in the electron layer explains why some people have been electrocuted by BL. Experiments indicate that BL radiates microwaves upon exploding and this is consistent with the model. The fact that this novel model of BL can explain these and other observations is strong evidence that the model should be taken seriously.

  7. Fluorescence caused by ionizing radiation from ball lightning: Observation and quantitative analysis

    Science.gov (United States)

    Stephan, Karl D.; Krajcik, Rozlyn; Martin, Rolf J.

    2016-10-01

    Ball lightning is a rare phenomenon, typically appearing as a glowing sphere associated with thunderstorms. In 2008 one of the authors witnessed a blue ball-lightning object hover in front of a glass window that appeared to glow yellow. Calibrated quantitative fluorometry measurements of the window show that the glow was probably due to fluorescence caused by ionizing radiation (UV or possibly X rays). Based on the measurements performed, estimates of the total ionizing-radiation power emitted by the object range upward from about 10 W. These are among the most reliable semi-quantitative measurements so far of ionizing-radiation output from a ball-lightning object.

  8. Recent Lightning Experiments at the International Center for Lightning Research and Testing: From Ball Lightning to Gamma Rays

    Science.gov (United States)

    Uman, M. A.

    2008-12-01

    Recent lightning data and the instrumentation used to acquire it at the UF-FIT International Center for Lightning Research and Testing, located on about 1 square kilometer of flat ground at the Camp Blanding Army National Guard Base in north-central Florida, are discussed. The progress of several on-going studies is reviewed: (1) understanding the physics of the "classical" rocket-and-wire triggering of lightning from natural overhead thunderclouds, (2) attempting to generate ball lightning by allowing triggered-lightning to strike various materials and objects (e.g., tree-trunk sections, pools of salt water, silicon powder), (3) measuring the very close (100 m to 1 km) electric and magnetic fields of natural cloud-to-ground lightning, and (4) probing the relationship between lightning processes and the x-rays and gamma-rays associated with them.

  9. 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.

  10. Charge on luminous bodies resembling natural ball lightning produced via electrical arcs through lump silicon

    Science.gov (United States)

    Porter, Christina L.; Miley, Galen P.; Griffiths, David J.; Sánchez, Erik

    2014-12-01

    A phenomenon resembling natural ball lightning can be produced via electrical arcing through silicon. We use lump silicon instead of silicon wafers to achieve higher production rates and larger, longer-lived luminous balls than previously reported. The luminous balls consist of a silicon core surrounded by a porous network of loosely bound silicon dioxide nanoparticles. We find that the balls carry a small net charge on the order of 10-12 C and propose that the nanoparticles are electrostatically bound to the core due to this charge.

  11. An Analysis of Ball Lightning-Aircraft Incidents

    Science.gov (United States)

    Doe, R. K.; Keul, A. G.; Bychkov, V.

    2009-12-01

    Lightning is a rare but regular phenomenon for air traffic. Research and design have created aircraft that withstand average lightning strikes. Ball lightning (BL), a metastable, rare lightning type, is also observed from (and within) aircraft. Science and the media focused on individual BL incidents and did not analyze general patterns. Lacking established incident reporting channels, most BL observations are still passed on as “aviation lore”. To overcome this unsatisfactory condition, the authors collected and analyzed an international data bank of 87 BL-aircraft case histories from 1938 to 2007. 37 Russian military and civil BL reports were provided by the third author. Of the whole sample, 36 (41%) cases occurred over Russia/RF/SU, 24 (28%) over USA/Canada, 23 (26%) over Europe, and 4 (5%) over Asia/Pacific. Various types of military (US: C-54/141, B-52, KC-97/135 Stratotankers, C130, P-3 Orion, RF/SU: PO-2, IL, SU, TU, MIG; Nimrod, Saab-105) and civilian aircraft (US: DC-3/6, Metroliner, B-727/737/757/777, RF/SU: AN, TU; VC-10, Fokker F-28, CRJ-200), as well as general aviation (C-172, Falcon-20), were involved. BL reports show a flat annual April to August maximum. At BL impact, 15 aircraft were climbing, 7 descending; most were at cruising altitude. 42 (48%) reported BL outside the aircraft, 37 (43%) inside, 7 (8%) both in-and outside. No damage was reported in 34 (39%) cases, 39 objects (45%) caused minor damage, 11 major damage (13%), 3 even resulted in military aircraft losses. 3 objects caused minor, 1 major crew injury. 23 damage cases were associated with BL inside the fuselage; all 4 crew injury cases were of that BL type. Mean size is described as 25 cm, sometimes over 1 m, color 30% in the yellow-red, 10% in the blue-green spectral region, 8% white, duration around 10 seconds, sometimes over 1 minute. 33 (38%) incidents ended with an explosion of the object. Thunderstorm conditions were reported by 25 (29%) of the observers, 9 (10%) said there

  12. Formation Mechanism and Characteristics Research of Ball Lightning Based on Vortex Model

    Science.gov (United States)

    Li, Zi-Cheng; Yang, Guo-Hua

    2011-05-01

    The strange characteristics of ball lightning are considered as a question hard to explain. In order to solve the problem, in this paper a complete model of plasma vortex is presented for the ball lightning. By ideal MHD equations, through imposing disturbance to plasma column, the possibility of sausage and kink instability of the lightning channel is analyzed from the perspective the minimum potential energy. The conclusion is that the kink instability (m = 1) is most prone to occur. And when instability occurs, because of the difference of the magnetic field in the twisted area, the magnetic pressure makes the trend further and therefore forming the plasma vortex that may eventually turn into ball lightning if the energy of the vortex is large enough. The existence of the vortex makes ball lightning have a short period of time stability. By the proposed model, the ball lightning features that are hard to understand in the past are explained. In this paper, the reason for bead lightning is also explained from the perspective of the sausage instability.

  13. Ball lightning passage through a glass without breaking it

    Science.gov (United States)

    Bychkov, Vladimir L.; Nikitin, Anatoly I.; Ivanenko, Ilia P.; Nikitina, Tamara F.; Velichko, Alexander M.; Nosikov, Igor A.

    2016-12-01

    In long history of ball lightning (BL) theory development there is a struggle of two concepts. According to the first one, BL - is a high frequency electrical discharge, burning in the air due to action of alternating electric field or a continuous current generated by an external source of energy. According to the second one, the BL is a material body, storing energy within itself. Data banks of BL observations give evidence that BL can pass through glasses, leaving no traces on them. Supporters of the first concept consider this as the proof of the correctness of the "electric field" BL nature. Representation of BL as a material body with internal source of energy explains most of its features, but has difficulties in explanation of BL penetration through glasses. We describe results of research of the glass, through which BL freely passed, that was observed by one of the authors. They proved the presence of traces left by BL. With a help of optical and scanning microscopes and laser beam probing of the glass, that experienced action of 20 cm BL, we have found traces in it: in the glass we found a region of 1-2 mm, at the center of which a cavity of 0.24 mm diameter is located. This gives evidence to a "material" nature of BL. BL possibility to pass through small holes and its ability to "make" such holes poses a number of difficult issues to researchers indicated in the article.

  14. Properties of short-living ball lightning produced in the laboratory

    Science.gov (United States)

    Egorov, A. I.; Stepanov, S. I.

    2008-06-01

    An experimental setup for highly reproducible generation of artificial ball lightnings is implemented. Thousands of floating glowing plasmoids 12-20 cm in diameter are produced. Research facilities for studying the plasmoids are developed. It is found that short-lived ball lightnings live for about 1 s and carry an electric charge. The lightnings are shown to have a complex structure: a central kernel containing a rich variety of hydrated ions and aerosol of decay products is surrounded by a thin negatively charged shell.

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

    Energy Technology Data Exchange (ETDEWEB)

    Roth, J.R. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-05-01

    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{sup 3}, well above the limit of chemical energy storage of, for example, TNT at 2000 J/cm{sup 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.

  16. 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.

  17. OH Radical and a Drizzling Water Jet Production from the Ball-Lightning Discharge in Water

    Science.gov (United States)

    Maeyama, Mitsuaki; Tanaka, Yasutomo

    The ball lightning, or fireball discharge using the typical electrode configuration was reported to produce a long-living spherical plasmoid with radius exceed 10 cm at atmospheric pressure. In this study, we investigated the relationship between a optical output emitted from OH radicals and discharge conditions of the ball-lightning electrode configuration, and discussed its possibility to the water treatment process. As a results, in both polarity cases of the charged voltage V0, a ball-lightning discharge and the optical emission from OH radicals as a major radiation can be generated on the condition |V0| > 4 kV in tap water. Furthermore, an intensive upward water jet from the rod electrode is observed in case of positive polarity and in 0.2% NaCl solution, which is composed of drizzling water drops near the rod electrode.

  18. Implications of the visual appearance of ball lightning for luminosity mechanisms

    Science.gov (United States)

    Stephan, Karl D.

    2012-11-01

    Observations of ball lightning continue to pose one of the more difficult unsolved problems in atmospheric physics. Lack of quantitative data has frustrated attempts to explain how the objects emit light. We examine three leading theories for the immediate cause of light emission: excitation of plasma, small hot individual particles suspended in air, and hot fractal clusters of small particles. Using radiative transport theory, we find quantitative values for the ranges of particle density and temperature required to produce luminous intensities consistent with the bulk of reported observations, as well as estimates of power requirements for each mechanism. We conclude that all of these mechanisms are consistent with many ball-lightning observations, and that more than one of them may be involved in the luminosity of ball lightning.

  19. Extreme ball lightning event of August 6, 1868 in County Donegal, Ireland.

    Energy Technology Data Exchange (ETDEWEB)

    VanDevender, J. Pace; McGinley, Niall (Ardaturr, Donegal, Ireland); van Doorn, Peter (Tornado and Storm Research Organization, TORRO, Thelwall, Warrington, UK); Wilson, Peter (University of Ulster, Northern Ireland, UK); VanDevender, Aaron P. (National Institute of Standards and Technology, Boulder, CO)

    2008-04-01

    Although laboratory experiments have produced glowing balls of light that fade in <1 s after external power is removed and theories have been proposed to explain low-energy events, energetic ball lightning is not understood. A seminal event that illuminates the fundamental nature of ball lightning is needed to advance our understanding of the phenomenon. We report such a seminal event: the energetic ball lightning event of August 6, 1868, in County Donegal, Ireland, extensively reported to the Royal Society by M. Fitzgerald. It lasted for 20 minutes, left a 6 m square hole and a 100 m long by 1.2 m deep trench, tore away a 25 m long and 1.5 m deep stream bank that diverted the course of the stream, and terminated by producing a shallow cave in the opposite bank of the stream. We found and characterized the site and show that the geomorphology and carbon dating support the account by M. Fitzgerald. We find that the excavation is not consistent with chemical, nuclear, or electrostatic forces but is consistent with Analysis of the event and the local conditions in 2006 is consistent with magnetic induction at {approx} 1 MHz frequency expelling the moderately conductive, water saturated peat down to the underlying clay/rock layer. The 60-cm diameter--which diminished to 10 cm diameter without reducing the impact of the ball lightning on the environment--and the size of the depressions, the yield strength of the peat, and the lack of any mention of smoke or steam in Fitzgerald's report would be consistent with the core of the ball lightning being a magnetically levitated mini black hole weighing more than 20,000 kg. The results suggest that such energetic ball lightning should be detectable at great distances by its electromagnetic emissions, which might provide a characteristic signature to reveal the source of the energy and the equilibrium configuration of the contained currents. Unexplained intermittent emissions in the MHz range are necessary but not

  20. Ball lightning as a spherical plasma configuration of relevance to industrial plasma engineering

    International Nuclear Information System (INIS)

    Roth, J.R.

    1992-01-01

    One of the most interesting spherical plasma configurations found in nature is ball lightning, which has been extensively observed in atmospheric air, usually in association with thunderstorms. If the physical processes responsible for ball lightning were understood, this knowledge would have very interesting implications not only for fusion research, but also for industrial plasma engineering. The ability to create a steady-state atmospheric glow discharge would allow many surface modification and other plasma processing applications to be carried out under atmospheric conditions, rather than in expensive vacuum systems which enforce batch processing operations. The existence of ball lightning offers encouragement for the belief that a steady-state atmospheric glow discharge may be possible. Much progress has been made in theoretical attempts to understand ball lightning, perhaps the most comprehensive of which is the Koloc model. This and related models have not satisfactorily dealt with the long plasma lifetimes in the face of electron scattering at atmospheric density. This leads to an unsatisfactory aspect of the Koloc model, the requirement of a shell of relativistic electrons with very low Coulomb scattering cross sections. This last major conceptual roadblock in understanding ball lightning may have been removed by the recent suggestion of Witalis who pointed out that atmospheric gases, or their products, can exhibit the Ramsauer effect, extremely low electron scattering cross sections at low electron kinetic temperatures, on the order of one eV. This recent progress in ball lightning models has stimulated research aimed at producing a steady state glow discharge in air at atmospheric pressure. Such a glow discharge in argon with a few ppm of acetone has been reported by Kanda, et al. At the UTK Plasma Science Laboratory, the authors have generated at 2.8 liter plasma in a steady-state atmospheric pressure glow discharge in helium and other gases

  1. Ball clay

    Science.gov (United States)

    Virta, Robert L.

    2010-01-01

    The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

  2. Ball Lightning Aerosol Electrochemical Power Source or A Cloud of Batteries

    Science.gov (United States)

    Meshcheryakov, Oleg

    2007-07-01

    Despite numerous attempts, an adequate theoretical and experimental simulation of ball lightning still remains incomplete. According to the model proposed here, the processes of electrochemical oxidation within separate aerosol particles are the basis for this phenomenon, and ball lightning is a cloud of composite nano or submicron particles, where each particle is a spontaneously formed nanobattery which is short-circuited by the surface discharge because it is of such a small size. As free discharge-shorted current loops, aerosol nanobatteries are exposed to a powerful mutual magnetic dipole dipole attraction. The gaseous products and thermal energy produced by each nanobattery as a result of the intra-particle self-sustaining electrochemical reactions, cause a mutual repulsion of these particles over short distances and prevent their aggregation, while a collectivization of the current loops of separate particles, due to the electric arc overlapping between adjacent particles, weakens their mutual magnetic attraction over short distances. Discharge currents in the range of several amperes to several thousand amperes as well as the pre-explosive mega ampere currents, generated in the reduction oxidation reactions and distributed between all the aerosol particles, explain both the magnetic attraction between the elements of the ball lightning substance and the impressive electromagnetic effects of ball lightning.

  3. The Proton Conductivity of Condensed Phases of Water:. Implications on Linear and Ball Lightning

    Science.gov (United States)

    Tennakone, Kirthi

    2006-06-01

    Ice is a proton conductor, with conductivities ranging from 10-6 to 10-9 S m-1 depending on the purity of the sample. Electronically ice is highly insulating with conductivity of the order 10-12 S m-1 or below. Mobile protons in ice originate from disruption of hydrogen bonds and strong electric fields enhance bond breakage. Ice particle acquires electrification during formation of thunder clouds and ice play a crucial in role charge separation leading to lightning. It is suggested that charges of ice particles in clouds originates from inductive charge separation and transfer of the mobile positive charge to the streaming air. Thus ice particles gain a negative charge and moist air drifting upwards becomes more positive. Consequently, most thunder clouds have a negative charge in the region closer to the ground. Although many explanations are proposed, the elusive phenomenon of ball lightning continues to resist theoretical understanding and laboratory reproduction. Ball lightning originates in the electrical active atmosphere as a luminous sphere drifting in air with the capability of bouncing from walls and penetrating openings smaller than the ball. It is suggested that ball lightning is a negatively charged sphere constituted of an outer shell of ice. Water dipoles are oriented radially by the electric field and protons acquire a high mobility in the tangential direction. As the electron conductivity of the shell in radial direction is very small, the charge slowly leaks to the atmosphere as a corona discharge. Model naturally explains how the ball could penetrate a hole or bounce from a surface as a differential electrostatic stress could develop in the ball as result of the proton conductivity. Details of the models and suggestions for experimental verification of the proposed concepts will be presented.

  4. Ball lightning caused by a semi-relativistic runaway electron avalanche

    Science.gov (United States)

    Paiva, Geron S.; Taft, Carlton A.; Furtado, Nelson C. C. P.; Carvalho, Marcos C.; Hering, Eduardo N.; Vinícius, Marcus; Ronaldo, F. L.; De la Cruz, Neil M.

    2014-12-01

    Ball lightning (BL) is observed as a luminous sphere in regions of thunderstorm activity. There are many reports of BL forming in total absence of thunderclouds, associated with earthquakes and volcanoes. In this latter case, BL has been known to appear out of “nowhere”. In this work, a hypothesis on BL formation is presented involving the interaction between very low frequency (VLF) radio waves and atmospheric plasmas. High-velocity light balls are produced by ionic acoustic waves (IAWs) interacting with a stationary plasma. Several physical properties (color, velocity, and fragmentation) observed in the BL phenomenon can be explained through this model.

  5. Great balls of fire

    Science.gov (United States)

    Stenhoff, Mark; reader01; jjherrera

    2014-03-01

    In reply to the physicsworld.com news article “Burning soil fuels ball lightning” (9 January, http://ow.ly/tl8aO) on evidence that a burning core of soil acts as an energy source for ball lightning.

  6. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The state of the ball clay industry in 1999 is presented. Record highs in the sales and use of ball clay were attained in 1999 due to the continued strength of the U.S. economy. U.S. production was estimated at 1.25 million st for the year, with more than half of that amount mined in Tennessee. Details of the consumption, price, imports, and exports of ball clay in 1999 and the outlook for ball clay over the next few years are provided.

  7. Further Insight into the Nature of Ball-Lightning-Like Atmospheric Pressure Plasmoids

    Science.gov (United States)

    Friday, David M.; Broughton, Peter B.; Lee, Tanner A.; Schutz, Garrett A.; Betz, Jeremiah N.; Lindsay, C. Michael

    2013-10-01

    Known since antiquity, ball lightning is a natural, long-lived plasma-like phenomenon associated with thunderstorms and is not well understood due to its rarity and unpredictability. A recently discovered laboratory phenomenon with striking similarity to ball lightning is observed when a high-power spark is discharged from a cathode protruding from a grounded electrolyte solution. Whereas several investigations of these long-lived plasmas have been reported over the past decade, the underlying chemical and physical processes are still unknown. The present work attempts to gain further insight into this phenomenon by examining the effect of electrolyte pH on the plasmoid and observing the chemical and physical structure of the plasmoid using high-speed schlieren videography and FTIR absorption spectroscopy. The results indicate that the lifetime and size of the plasmoid slightly increase as the pH of isoohmic electrolyte solutions deviate from neutrality. The observed absorption spectra of the plasmoids exhibit absorption cross sections in the 620-700, 1500-1560, 2280-2390, and 3650-4000 cm-1 ranges, the last attributed to the presence of water clusters. Finally, schlieren images revealed a single, sharp density gradient at the boundary layer of the top and sides of the expanding ball-shaped plasmoid, and turbulent mixing below the ball.

  8. A Discussion On A Physical Model Of Ball Lightning And UFO

    Directory of Open Access Journals (Sweden)

    Ivan L. Bajak

    2017-07-01

    Full Text Available It is proposed that the ball lightning and UFO are analogous objects. The variety of different observations is explained. It is proposed on a uniform basis using a hypothesis that the ball lightning and UFO are created like a spherical capacitor filled by polar molecules mainly and in some cases by various chemicals which influence the final manifest of the object. A mechanism of a formation of the spherical capacitor is discussed. A peculiar behavior like e.g. sudden change of direction of motion shape of disc and possible penetration through wall is explained as a consequence of internal structure of the object. Finally an experimental verification of the hypothesis is suggested.

  9. A Ball Lightning Model as a Possible Explanation of Recently Reported Cavity Lights

    Energy Technology Data Exchange (ETDEWEB)

    Fryberger, David; /SLAC

    2009-08-04

    The salient features of cavity lights, in particular, mobile luminous objects (MLO's), as have been experimentally observed in superconducting accelerator cavities, are summarized. A model based upon standard electromagnetic interactions between a small particle and the 1.5 GHz cavity excitation field is described. This model can explain some features of these data, in particular, the existence of particle orbits without wall contact. While this result is an important success for the model, it is detailed why the model as it stands is incomplete. It is argued that no avenues for a suitable extension of the model through established physics appear evident, which motivates an investigation of a model based upon a more exotic object, ball lightning. As discussed, further motivation derives from the fact that there are significant similarities in many of the qualitative features of ball lightning and MLO's, even though they appear in quite different circumstances and differ in scale by orders of magnitude. The ball lightning model, which incorporates electromagnetic charges and currents, is based on a symmetrized set of Maxwell's equations in which the electromagnetic sources and fields are characterized by a process called dyality rotation. It is shown that a consistent mathematical description of dyality rotation as a physical process can be achieved by adding suitable (phenomenological) current terms to supplement the usual current terms in the symmetrized Maxwell's equations. These currents, which enable the conservation of electric and magnetic charge, are called vacuum currents. It is shown that the proposed ball lightning model offers a good qualitative explanation of the perplexing aspects of the MLO data. Avenues for further study are indicated.

  10. Micro ball lightning and its accelerator proposed to control natural phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Taka-aki [Hokkaido Univ., Sapporo (Japan)

    2002-09-01

    Micro Ball Lightning (BL) was recently discovered in laboratory. It was also observed during natural phenomena such as volcanic eruption and earthquake. This paper described a brief review of micro BL observed in laboratory as well as during two natural phenomena. Being based on a hypothesis of that those natural phenomena could have been caused by explosive reactions of micro BL, a potential accelerator of micro BL was proposed to control the natural phenomena. (author)

  11. Micro ball lightning and its accelerator proposed to control natural phenomena

    CERN Document Server

    Matsumoto, T A

    2002-01-01

    Micro Ball Lightning (BL) was recently discovered in laboratory. It was also observed during natural phenomena such as volcanic eruption and earthquake. This paper described a brief review of micro BL observed in laboratory as well as during two natural phenomena. Being based on a hypothesis of that those natural phenomena could have been caused by explosive reactions of micro BL, a potential accelerator of micro BL was proposed to control the natural phenomena. (author)

  12. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2013-01-01

    Four companies — H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co. and Unimin Corp. — mined ball clay in five U.S. states in 2012. Production, on the basis of preliminary data, was 900 kt (992,000 st), with an estimated value of $42.3 million. This was a slight increase in tonnage from 886 kt (977,000 st), with a value of $40.9 million in 2011. Tennessee was the leading ball clay producing state, with 63 percent of domestic production, followed by Texas, Mississippi, Kentucky and Indiana. Reported ball clay production from Indiana probably was fire clay rather than ball clay. About 69 percent of total ball clay production was airfloat, 20 percent was crude and 11 percent was water-slurried.

  13. Electron-Ionic Model of Ball Lightening

    OpenAIRE

    Fedosin, Sergey G.; Kim, Anatolii S.

    2001-01-01

    The model of ball lightning is presented where outside electron envelope is kept by inside volume of positive charges. The moving of electron in outside envelope is a reason of strong magnetic field, which controls the state of hot ionized air inside of ball lightning. The conditions of origins of ball lightning are investigated and the values of parameters for ball lightning of maximum power are calculated.

  14. Ball Lightning With Spiking and Cold Emission in the Maser-Caviton Interaction

    Science.gov (United States)

    Handel, P. H.; Carlson, G. A.; Leitner, J.

    2007-05-01

    The nonlinear system of maser and cold plasma caviton can sustain spiking oscillations around the stationary state. This is shown here in the linearized limit of small oscillations. The role of ionization and cold emission effects is considered, and the case of large spiking amplitudes is discussed qualitatively on this basis. This calculation allows us to predict the frequency of the often observed humming of ball lightning. Furthermore, four basic experiments are suggested, that should be performed in order to verify and further develop the present Maser-Soliton theory of ball lightning: comparative atmospheric absorption spectroscopy in thunderstorm conditions, electric field pulse experiment, wind tunnel experiment and laboratory ball lightning generation experiment. The latter experiment suggested is based on a 10-20KW Klystron amplifier with negative feedback, trying to simulate the behavior of the atmospheric maser. The klystron is connected through a directional coupler to a tuned resonator that serves as discharge chamber. From there, a wave guide completes the loop. An optical feedback strengthens the natural tendency of the klystron to spike almost instantaneously when the load decreases. The discharge sought is a glow at atmospheric pressure, at much lower temperature than the lowest temperature arch discharge ever obtained so far at normal pressure. At these low temperatures there are no electrons that could sustain the discharge. However, right when the discharge is dying, a powerful klystron spike is automatically caused by the sudden decrease of the load. This extracts electrons through cold (Fowler) emission, and rekindles the discharge. However, like in the case of the atmospheric maser, the presence of the large spike automatically stops the klystron power. The optical feedback is responsible in part for the fast reaction. Then the spiking cycle repeats itself. Our Maser-Soliton BL theory allows for the first time not only to understand the

  15. Spectroscopic Studies of a Low-Temperature Atmospheric Plasmoid Analogous to Ball Lightning

    Science.gov (United States)

    Dubowsky, Scott E.; Friday, David M.; Peters, Kevin C.; Perry, Richard H.; Zhao, Zhangji; Deutsch, Bradley; Bhargava, Rohit; Liu, Jui-Nung; McCall, Benjamin J.

    2014-06-01

    Atmospheric-pressure, low-temperature plasmas exist in nature in the form of ball lightning, and last year a natural ball lightning event was finally observed with scientific equipment. Production of ball lightning in the laboratory dates back to Tesla's work at Colorado Springs. Today, Tesla's ``fireballs" are easily produced in the laboratory by discharging kiloJoules of energy slightly above an electrolyte solution via a metal electrode. For the sake of clarity, those plasmas produced using this technique are referred to as ``plasmoids." Valuable information is obtained from previous experiments, such as the identification of water clusters and the temperature of the interior of plasmoids.c We perform mass spectrometry and Fourier-transform infrared emission spectroscopy in an effort to characterize these plasmoids. We present, to our knowledge, the first mass spectrometric data and infrared emission spectra of plasmoid discharges. Mass spectrometry reveals the presence of small protonated water clusters [H+(H_2O)_2, H+(H_2O)_3] and nitrogen-containing molecules [NO+, NO+-H_2O]. IR spectra exhibit signals observed in the water emission region (1300-2000 cm-1, 3000-4000 cm-1), and signals in several other regions of interest. Fundamental properties of these plasmoids including the electron energy distribution function, component densities, and collisional cross sections will be discussed. Cen, J.; Yuan, P.; Xue, S. Phys. Rev. Lett. 2014, 112, 035001 Tesla, N. Colorado Springs Notes 1899-1900; Marinčić, A., Ed.; Nolit: Beograd, Yugoslavia, 1978; pp 368-370 Friday, D.M.; Broughton, P.B.; Lee, T.A.; Schutz, G.A.; Betz, J.N.; Lindsay, C.M. J. Phys. Chem. A 2013, 117 (39), 9931-9940

  16. Recently reported sightings of ball lightning: observations collected by correspondence and Russian and Ukrainian sightings.

    Science.gov (United States)

    Abrahamson, John; Bychkov, A V; Bychkov, V L

    2002-01-15

    The observations in the first section of this paper were sent to John Abrahamson in response to the publication of a recent paper on ball lightning, with the correspondents either reading the original paper, or reports of it in popular science articles. A selection of the cases has been made, including those which showed interesting detail possibly useful in debating ball lightning mechanisms. Any inserted text within parenthesis is the observer's response to follow-up queries from J.A. The age of the observer (where noted) is that at the time of the observation. Three observations (1 q-s) did not show motion independent of their surroundings, but have been included because of their other similarities to ball lightning. It is interesting to note the high proportion (greater than 0.5) of scientifically or technically trained observers in this collection. The data presented in the second section of this paper come from both letters and interviews. Our interview questionnaire consisted of 46 questions and was mostly carried out in quiet conditions. Observations in 2 a, e, h, l, m, q-t were corrected during several (two or three) interviews. Heading each observation case we note the most unusual property of the object. Ball lightning appears in Russia and the Ukraine usually in summer (June-August), and more rarely in spring (March-May), or autumn (September-November). It appears usually during the daytime, 13:00-17:00 h, when most summer thunderstorms take place. Observers in their descriptions usually use the term "morning" to describe the period from 06:00 to 11:00 h, "daytime" for 12:00-18:00 h, and "evening" for 19:00-21:00 h. The term "time' means the local time, and sometimes it is difficult to compare it with the local geographic time due to frequent official state summer-winter time changes. The decree time in Russia can in general differ from the geographic time by 1-2 h.

  17. Lightning ball: experiments on creation and hypotheses (comment on 'Energy density calculations for ball-lightning-like luminous silicon balls' by G S Paiva, J V Ferreira, C C Bastos, M V P dos Santos, A C Pavao)

    Energy Technology Data Exchange (ETDEWEB)

    Shabanov, Gennadii D [B P Konstantinov St. Petersburg Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina, Leningrad region (Russian Federation)

    2010-05-11

    The problems addressed in this paper include estimating: the energy density of luminous silicon balls, the density range of a natural lightning ball, and whether and how the object created and described in the commented paper (Usp. Fiz. Nauk 180 218 (2010) [Phys. Usp. 53 (2) 209 (2010)]) corresponds to the natural phenomenon. (letters to the editors)

  18. LETTERS TO THE EDITORS: Lightning ball: experiments on creation and hypotheses(comment on "Energy density calculations for ball-lightning-like luminous silicon balls" by G S Paiva, J V Ferreira, C C Bastos, M V P dos Santos, A C Pavão)

    Science.gov (United States)

    Shabanov, Gennadii D.

    2010-05-01

    The problems addressed in this paper include estimating: the energy density of luminous silicon balls, the density range of a natural lightning ball, and whether and how the object created and described in the commented paper (Usp. Fiz. Nauk 180 218 (2010) [Phys. Usp. 53 (2) 209 (2010)]) corresponds to the natural phenomenon.

  19. The similarities between the hallucinations associated with the partial epileptic seizures of the occipital lobe and ball lightning observations

    Science.gov (United States)

    Cooray, G. K.; Cooray, V.

    2007-12-01

    Ball Lightning was seen and described since antiquity and recorded in many places. Ball lightning is usually observed during thunderstorms but large number of ball lightning observations is also reported during fine weather without any connection to thunderstorms or lightning. However, so far no one has managed to generate them in the laboratory. It is photographed very rarely and in many cases the authenticity of them is questionable. It is possible that many different phenomena are grouped together and categorized simply as ball lightning. Indeed, the visual hallucinations associated with simple partial epileptic seizures, during which the patient remains conscious, may also be categorized by a patient unaware of his or her condition as ball lightning observation. Such visual hallucinations may occur as a result of an epileptic seizure in the occipital, temporo-occipital or temporal lobes of the cerebrum [1,2,3]. In some cases the hallucination is perceived as a coloured ball moving horizontally from the periphery to the centre of the vision. The ball may appear to be rotating or spinning. The colour of the ball can be red, yellow, blue or green. Sometimes, the ball may appear to have a solid structure surrounded by a thin glow or in other cases the ball appears to generate spark like phenomena. When the ball is moving towards the centre of the vision it may increase its intensity and when it reaches the centre it can 'explode' illuminating the whole field of vision. During the hallucinations the vision is obscured only in the area occupied by the apparent object. The hallucinations may last for 5 to 30 seconds and rarely up to a minute. Occipital seizures may spread into other regions of the brain giving auditory, olfactory and sensory sensations. These sensations could be buzzing sounds, the smell of burning rubber, pain with thermal perception especially in the arms and the face, and numbness and tingling sensation. In some cases a person may experience only

  20. Drift motion of the magnetic monopole of Poljakov-'t Hooft in the air and the ball-lightning phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Korshunov, V.K. (Korshunov Valentin Konstantinovich, Krupskoy Street 78-A, 614077 PERM-77 (SU))

    1990-08-30

    In this paper by virtue of theoretical investigations of V. Rubakov on nucleons and nuclei decay with monopole-nucleon interaction, a qualitative analysis of the drift motion of the mon in the air is conducted. The physical picture obtained coincided in detail with the descriptions of the ball-lightning, for which reason ball- lightning is considered evidence for the magnetic monopole.

  1. SOME RESULTS OF EXPERIMENTAL RESEARCH ON ARTIFICIAL BALL LIGHTNING LOW-ENERGY PLASMOIDS IN A HIGH-VOLTAGE LABORATORY.

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2013-10-01

    Full Text Available First results of experimental laboratory-scale reproduction of spheroidal low-energy plasmoids of an artificial ball lightning are given. The data obtained indicate a possibility in principle of reliable generation of such plasmoids in the air atmosphere via the discharge circuit of a high-voltage installation comprising a curved arc discharge channel between a graphite electrode and technical water surface. The artificial 0.3m-diameter ball lightning plasmoid lifetime was less than 0.6 s in the experiments conducted.

  2. Some of the ball lightning observations could be phosphenes induced by energetic radiation from thunderstorms and lightning

    Science.gov (United States)

    Cooray, G. K.; Cooray, G. V.; Dwyer, J. R.

    2011-12-01

    Ball Lightning was seen and described since antiquity and recorded in many places. However, so far no one has managed to generate them in the laboratory. It is possible that many different phenomena are grouped together and categorized simply as ball lightning. One such phenomenon could be the phosphenes induced in humans by energetic radiation and particles from lightning and thunderstorms. A phosphene is a visual sensation that is characterized by perceiving luminous phenomena without light entering the eye. Phosphenes are generated when electrical signals are created in the retina or the optical nerve by other means in the absence of light stimuli. The fact that energetic radiation produced by radium can give rise to phosphenes was first noted by Giesel in 1899 [1]. A resurge of studies related to the creation of phosphenes by energetic radiation took place after the reports of phosphenes observed in space by Apollo astronauts and first reported by Buzz Aldrin after the Apollo 11 flight to the moon in 1969 [2]. The shapes of the phosphenes observed by astronauts were either rods, comet shaped, or comprised of a single dot, several dots or blobs. The colors were mostly white, but some had been colored yellow, orange, blue, green or red. The majority of the astronauts had perceived some kind of motion in association with the phosphenes. Most of the time, they were moving horizontally (from the periphery of the vision to the center) and sometimes diagonally, but never vertically. Subsequent studies conducted in space and ground confirmed the creation of phosphenes by energetic radiation. From these studies the threshold energy dissipation in the eye tissue necessary for phosphenes induction was estimated to be 10 MeV/cm. In the present study a quantitative analysis of the energetic radiation generated in the form of X-rays, Gamma rays and relativistic electrons by thunderstorms and lightning was made to investigate whether this radiation is strong enough to induce

  3. Ban Deodorant Ball Mortar.

    Science.gov (United States)

    Carpenter, D. Rae, Jr.; And Others

    1988-01-01

    Discusses a demonstration of vertical collision of two balls. Shows the theoretical height ratio using mathematical expression and diagrams. Compares it with researchers' experimental results. Expands the two-ball collision to multi-ball system. (YP)

  4. IMPROVEMENT OF A MICRODIPOLE MODEL OF A BALL LIGHTNING AND ELECTRODYNAMIC DEVELOPMENT OF THE THEORY OF THIS PHENOMENON.

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2013-06-01

    Full Text Available A new electrodynamic model of a ball lightning (BL containing an internal toroidal high-temperature energy core and an external electro-neutral highly-polarized water shell is introduced. The BL energy core is formed by electron and proton microtori with intrinsic oppositely directed elementary spiral-circular currents. The BL core spiral-circular electron currents of conductivity create an enveloping strong pulsed azimuth magnetic field and a superstrong vortex radial electrical field.

  5. FOUR BALL BEST BALL 1

    Directory of Open Access Journals (Sweden)

    Geoff Pollard

    2010-03-01

    Full Text Available In this paper a four-ball-best-ball (4BBB model for pairs of golf players is set up. The 4BBB match-play scoring system is seen to satisfy a basic requirement of fairness. It is shown that it is not strictly possible to rate individual players as 4BBB players. However, a (reasonably broad class of individual players is identified such that it is possible to rate them individually as 4BBB players. The capacity of an individual to play birdies is seen to be a very important determinant in being a successful member of a 4BBB pair, but there are other minor factors as well. Consideration is given to equal and unequal 4BBB pairs. The transitive law is seen to apply for 4BBB pairs. Thus, if pair A is better than pair B, and pair B is better than pair C, then pair A must be better than pair C. Correspondingly, if pair A is equal to pair B, and pair B is equal to pair C, then pair A is equal to pair C. Consideration is given to some strategic issues in 4BBB match-play golf. For example, the conditions under which a player should take a greater risk and have a higher probability of obtaining a bogie in order to achieve a higher probability of scoring a birdie, are determined. Also, the conditions under which a player, noting that his partner is about to have a ‘bad’ hole and score only a par or a bogie, should ‘play safe’, are determined. Thirdly, players who can interact in certain ways are seen to have an advantage over those pairs that cannot do this. Finally, one pair’s optimal strategy when they see that their opponents are about to score a par or a bogie, but not a birdie, is analyzed

  6. Observations of Ball-Lightning-Like Plasmoids Ejected from Silicon by Localized Microwaves

    Directory of Open Access Journals (Sweden)

    Michael Sztucki

    2013-09-01

    Full Text Available This paper presents experimental characterization of plasmoids (fireballs obtained by directing localized microwave power (<1 kW at 2.45 GHz onto a silicon-based substrate in a microwave cavity. The plasmoid emerges up from the hotspot created in the solid substrate into the air within the microwave cavity. The experimental diagnostics employed for the fireball characterization in this study include measurements of microwave scattering, optical spectroscopy, small-angle X-ray scattering (SAXS, scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDS. Various characteristics of these plasmoids as dusty plasma are drawn by a theoretical analysis of the experimental observations. Aggregations of dust particles within the plasmoid are detected at nanometer and micrometer scales by both in-situ SAXS and ex-situ SEM measurements. The resemblance of these plasmoids to the natural ball-lightning (BL phenomenon is discussed with regard to silicon nano-particle clustering and formation of slowly-oxidized silicon micro-spheres within the BL. Potential applications and practical derivatives of this study (e.g., direct conversion of solids to powders, material identification by breakdown spectroscopy (MIBS, thermite ignition, and combustion are discussed.

  7. Fusion characteristics of ball lighting like configurations

    Energy Technology Data Exchange (ETDEWEB)

    Sanduloviciu, M.; Lozneanu, E. [Universitatea A1. I. Cuza, Iasi (Romania)

    1997-12-31

    Assuming that an already proposed self-organization physical scenario is at the origin of both ball lightnings as well as fireballs produced in high intensity electrical discharges, we suggest a new possibility to create fusion relevant ball lightning like configurations in laboratory. Perhaps this becomes possible by prolonging in a controllable way their lifetime and energy content. (author)

  8. 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…

  9. 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)

  10. 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.

  11. The spinning ball spiral

    Science.gov (United States)

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

    2010-09-01

    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.

  12. Ball Collision Experiments

    Science.gov (United States)

    Cross, R.

    2015-01-01

    Experiments are described on collisions between two billiard balls and between a bat and a ball. The experiments are designed to extend a student's understanding of collision events and could be used either as a classroom demonstration or for a student project.

  13. Punjab Ball Menu

    OpenAIRE

    Hobday, E, fl. 1905, artist

    2003-01-01

    A photograph of the exterior of a menu from the 'Punjab Ball'. The menu is decorated on both the inside and outside with illustrations by 'E. Hobday'. Inside the menu, in pen, is written: 'Lahore, Ball in Montgomery Hall, Nov 30th. 1905'.

  14. Happy Balls, Unhappy Balls, and Newton's Cradle

    Science.gov (United States)

    Kagan, David

    2010-01-01

    The intricacies of Newton's Cradle are well covered in the literature going as far back as the time of Newton! These discussions generally center on the highly elastic collisions of metal spheres. Thanks to the invention of happy and unhappy balls, you can build and study the interaction of less elastic systems (see Fig. 1).

  15. 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.

  16. Ball lightning as a self-organizing process of a plasma-plasma interface and El Naschie's {epsilon}{sup ({approx})} space-time

    Energy Technology Data Exchange (ETDEWEB)

    Agop, M. [Department of Physics, Technical ' Gh. Asachi' University, Blvd. Mangeron No. 64, Iasi 700029 (Romania)]. E-mail: magop@phys.tuiasi.ro; Murgulet, C. [Faculty of Physics, ' Al.I.Cuza' University, Blvd. Carol I No. 11, Iasi 700506 (Romania)

    2007-08-15

    In the fractal space-time theories, some properties of a ball lightning (BL) are established: the oscillation regimes, the hysteresis, the distributions of the potential, field and charge etc. In such a context, the Feynman-El Naschie hypothesis on the universality of the dipole-dipole interaction is confirmed and a connection between El Naschie's {epsilon}{sup ({approx})} space-time and Feigenbaum-Goldfain conjecture is given.

  17. Fiber ball imaging.

    Science.gov (United States)

    Jensen, Jens H; Russell Glenn, G; Helpern, Joseph A

    2016-01-01

    By modeling axons as thin cylinders, it is shown that the inverse Funk transform of the diffusion MRI (dMRI) signal intensity obtained on a spherical shell in q-space gives an estimate for a fiber orientation density function (fODF), where the accuracy improves with increasing b-value provided the signal-to-noise ratio is sufficient. The method is similar to q-ball imaging, except that the Funk transform of q-ball imaging is replaced by its inverse. We call this new approach fiber ball imaging. The fiber ball method is demonstrated for healthy human brain, and fODF estimates are compared to diffusion orientation distribution function (dODF) approximations obtained with q-ball imaging. The fODFs are seen to have sharper features than the dODFs, reflecting an enhancement of the higher degree angular frequencies. The inverse Funk transform of the dMRI signal intensity data provides a simple and direct method of estimating a fODF. In addition, fiber ball imaging leads to an estimate for the ratio of the fraction of MRI visible water confined to the intra-axonal space divided by the square root of the intra-axonal diffusivity. This technique may be useful for white matter fiber tractography, as well as other types of microstructural modeling of brain tissue. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. 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...

  19. Ball game popularity

    OpenAIRE

    Gregorič, Vanja

    2011-01-01

    In the diploma thesis I present ball games and how they are popular among children of 4th and 5th form of primary school. Sport activities play an important role when growing up and it is up to adults to provide children a certain amount of exercise in the pre-school period and during their schooling. It is important that one considers child's age and that the activities are represented through playing. Ball games are included in the curriculum in one of the sets in the first three years. In ...

  20. A Model of Ball Lightning as a Formation of Water Molecules Confining an Electric Charge and the Classical Theory of the Electron

    Science.gov (United States)

    Tennakone, K.

    2012-04-01

    Ball lightning or faintly luminous floating spheres with radii of the order of ten centimeters appearing transiently in air notably during stormy weather continue to remain an unresolved phenomenon. It is suggested that these objects are organized structures constituted of an electrically charged spherical thin shell of electro-frozen dipole oriented water molecules carrying an electric charge, balanced by the internal negative pressure and outward electrostatic stress. A model presented, resembling the classical theory of the electron with Poincare stresses explain almost all observed attributes of this phenomenon. The possibility of realizing macroscopic spherical surface charge distributions in the vacuum and their implication on the problem of electron are commented.

  1. 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.)

  2. Magnetohydrodynamics equilibrium of a self-confined elliptical plasma ball

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H. (CCAST (World Laboratory) P. O. Box 8730, Beijing 100080 and Institute of Mechanics, Academia Sinica, Beijing, People' s Republic of China (CN)); Oakes, M.E. (Department of Physics, University of Texas at Austin, Austin, Texas 78712 (USA))

    1991-08-01

    A variational principle is applied to the problem of magnetohydrodynamics (MHD) equilibrium of a self-contained elliptical plasma ball, such as elliptical ball lightning. The principle is appropriate for an approximate solution of partial differential equations with arbitrary boundary shape. The method reduces the partial differential equation to a series of ordinary differential equations and is especially valuable for treating boundaries with nonlinear deformations. The calculations conclude that the pressure distribution and the poloidal current are more uniform in an oblate self-confined plasma ball than that of an elongated plasma ball. The ellipticity of the plasma ball is obviously restricted by its internal pressure, magnetic field, and ambient pressure. Qualitative evidence is presented for the absence of sighting of elongated ball lightning.

  3. 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

  4. 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.

  5. 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.

  6. Individual ball possession in soccer.

    Science.gov (United States)

    Link, Daniel; Hoernig, Martin

    2017-01-01

    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.

  7. Solving ball lightning—A reply to Stefan and Massey (2008)

    Science.gov (United States)

    Coleman, Peter Francis

    2009-06-01

    Comments are made on the ball lightning paper of Stephan and Massey [Stefan, K.D., Massey, N., 2008. Burning molten metallic sphere: One class of ball lightning? Journal of Atmospheric and Solar-Terrestrial Physics 70, 1589-1596] that describes their [`]welding drop' theory. An alternative theory is offered based on combustion inside an atmospheric vortex. The [`]vortex fireball' hypothesis has good explanatory capability in regard to published ball lightning properties.

  8. Localized plasma balls

    Energy Technology Data Exchange (ETDEWEB)

    Figueras, Pau; Tunyasuvunakool, Saran [DAMTP, Centre for Mathematical Sciences,Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2014-06-04

    In this paper we numerically construct localized black hole solutions in the IR end of the confining geometry of the AdS soliton, Witten’s early holographic model for confinement. These black holes should be thought of as finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrized by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, these these black holes spread out in the directions parallel to IR end of the space-time, whilst their extent in the holographic radial direction remains finite. In these new black hole backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy.

  9. Localized plasma balls

    International Nuclear Information System (INIS)

    Figueras, Pau; Tunyasuvunakool, Saran

    2014-01-01

    In this paper we numerically construct localized black hole solutions in the IR end of the confining geometry of the AdS soliton, Witten’s early holographic model for confinement. These black holes should be thought of as finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrized by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, these these black holes spread out in the directions parallel to IR end of the space-time, whilst their extent in the holographic radial direction remains finite. In these new black hole backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy

  10. Behaviour of a Bouncing Ball

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    The bounce of a ball is a seemingly innocuous event that can be used to illustrate many aspects of elementary and even advanced mechanics. Both normal and oblique bounces on a rigid surface are considered in this article, emphasizing qualitative features of the bounce process. If the ball bounces at an oblique angle then it can slide throughout…

  11. Reflections on a Bouncing Ball

    Science.gov (United States)

    Rohr, Jim; Lopez, Veronica; Rohr, Tyler

    2014-01-01

    While observing the bounce heights of various kinds of sports balls dropped from different heights onto a variety of surfaces, we thought of the following question: Could measurements of drop and bounce heights of balls of different diameters, but of the same material, falling from different heights, but on the same surface, be expressed by a…

  12. Prediction of tar ball formation

    International Nuclear Information System (INIS)

    Khelifa, A.; Gamble, L.

    2006-01-01

    The presence of small tar balls ranging in size from less than a millimetre to 60 centimetres have been observed during cleanup assessment operations following accidental oil spills on water. The tar balls are composed of heavy oil residues and suspended particulate matter (SPM) from the water column. They can be found on shorelines, settled on the seafloor and floating at or near the water surface. Their abundance on the shorelines varies from site to site and depends on the conditions of the spill and mixing conditions. Aggregation between SPM and micro-sized oil droplets occurs naturally in coastal waters and enhances the dispersion of spilled oil. Although tar balls are among the important end states of spilled oil in the marine environment, no model exists to estimate the percentage of the spilled oil that becomes tar balls. This paper offered some insight into the modeling of tar ball formation. Current modeling understanding of oil-SPM aggregate formation was used to predict tar ball formation. The formation of oil droplets was examined with respect to a range of conditions under which the formation of large droplets is expected. The role of aggregation was then presented to demonstrate the effects of concentration and type of SPM on the buoyancy of tar balls. Good agreement was found between modeling results and field data reported in the literature regarding the size and density of tar balls. Oil viscosity and mixing energy were found to be the main factors controlling the formation of tar balls. The aggregation of tar balls with SPM and shoreline material results in significant increases or decreases in density, depending on the type and concentration of SPM. 42 refs., 2 tabs., 6 figs

  13. Crystal Ball at PEP

    International Nuclear Information System (INIS)

    Bartel, W.; Bulos, F.; Luke, D.; Peck, C.; Strauch, K.

    1975-01-01

    The modifications to the SPEAR version of the Crystal Ball required by the higher energies at PEP are discussed. Since the hadron multiplicity is expected to rise as log s, their average energy must rise. On the other hand, if the hadrons are produced in jets, the low energy part of their spectrum is not heavily depleted. This implies that modifications for high energy particles should not deteriorate low energy performance. An external iron calorimeter for measuring the high energy hadrons, charged and neutral, is considered. To improve the angular resolution on γ's, an active internal converter has been studied, estimates have been made of its expected performance, and difficulties requiring further study have been outlined

  14. On phenomenon of light radiation from miniature balls immersed in water

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P., E-mail: v_torchigin@mail.r [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278, Moscow (Russian Federation); Torchigin, A.V. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278, Moscow (Russian Federation)

    2010-01-11

    A phenomenon of light radiation from miniature silicon balls produced at arc discharge and immersed in water is described. Video film showing shining balls in a vessel with water is presented. An explanation of this phenomenon is considered. Similarities and differences of this phenomenon with a phenomenon of ball lightning are analyzed.

  15. On phenomenon of light radiation from miniature balls immersed in water

    Science.gov (United States)

    Torchigin, V. P.; Torchigin, A. V.

    2010-01-01

    A phenomenon of light radiation from miniature silicon balls produced at arc discharge and immersed in water is described. Video film showing shining balls in a vessel with water is presented. An explanation of this phenomenon is considered. Similarities and differences of this phenomenon with a phenomenon of ball lightning are analyzed.

  16. INVESTIGATION OF ANGULAR BALL BEARING WEAR

    Directory of Open Access Journals (Sweden)

    A. L. Savchenko

    2006-01-01

    Full Text Available Wearing process of balls in an angular ball bearing has been investigated in the paper. Force affecting a separator from the side of balls is determined theoretically. Wear rate may be calculated with a formula for abrasive wear while substituting numerical parameter values of the investigated ball bearing for formula symbols.

  17. Inscribed Balls and Their Centers

    Science.gov (United States)

    Balashov, M. V.

    2017-12-01

    A ball of maximal radius inscribed in a convex closed bounded set with a nonempty interior is considered in the class of uniformly convex Banach spaces. It is shown that, under certain conditions, the centers of inscribed balls form a uniformly continuous (as a set function) set-valued mapping in the Hausdorff metric. In a finite-dimensional space of dimension n, the set of centers of balls inscribed in polyhedra with a fixed collection of normals satisfies the Lipschitz condition with respect to sets in the Hausdorff metric. A Lipschitz continuous single-valued selector of the set of centers of balls inscribed in such polyhedra can be found by solving n + 1 linear programming problems.

  18. 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...

  19. Characterization and Infrared Emission Spectroscopy of Ball Plasmoid Discharges

    Science.gov (United States)

    Dubowsky, Scott E.; McCall, Benjamin J.

    2015-06-01

    Plasmas at atmospheric pressure serve many purposes, from ionization sources for ambient mass spectrometry (AMS) to plasma-assisted wound healing. Of the many naturally occurring ambient plasmas, ball lightning is one of the least understood; there is currently no solid explanation in the literature for the formation and lifetime of natural ball lightning. With the first measurements of naturally occurring ball lightning being reported last year, we have worked to replicate the natural phenomenon in order to elucidate the physical and chemical processes by which the plasma is sustained at ambient conditions. We are able to generate ball-shaped plasmoids (self-sustaining plasmas) that are analogous to natural ball lightning using a high-voltage, high-current, pulsed DC system. Improvements to the discharge electronics used in our laboratory and characterization of the plasmoids that are generated from this system will be described. Infrared emission spectroscopy of these plasmoids reveals emission from water and hydroxyl radical -- fitting methods for these molecular species in the complex experimental spectra will be presented. Rotational temperatures for the stretching and bending modes of H2O along with that of OH will be presented, and the non-equilibrium nature of the plasmoid will be discussed in this context. Cen, J.; Yuan, P,; Xue, S. Phys. Rev. Lett. 2014, 112, 035001. Dubowsky, S.E.; Friday, D.M.; Peters, K.C.; Zhao, Z.; Perry, R.H.; McCall, B.J. Int. J. Mass Spectrom. 2015, 376, 39-45.

  20. 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

  1. MIPP Plastic Ball electronics upgrade

    Science.gov (United States)

    Baldin, Boris; MIPP Collaboration

    2009-10-01

    An upgrade electronics design for Plastic Ball detector is described. The Plastic Ball detector was a part of several experiments in the past and its back portion (proposed to be used in Main Injector Particle Production (MIPP)) consists of 340 photomultipliers equipped with a sandwich scintillator. The scintillator sandwich has fast and slow signal component with decay times 10 ns and 1 μs, respectively. The upgraded MIPP experiment will collect up to 12,000 events during each 4 s spill and read them out in ˜50 s between spills. The MIPP data acquisition system will employ deadtime-less concept successfully implemented in Muon Electronics of Dzero experiment at Fermilab An 8-channel prototype design of the Plastic Ball Front-End (PBFE) implementing these requirements is discussed. Details of the schematic design, simulation and prototype test results are discussed.

  2. Charge-Dipole Acceleration of Polar Gas Molecules towards Charged Nanoparticles: Involvement in Powerful Charge-Induced Catalysis of Heterophase Chemical Reactions and Ball Lightning Phenomenon

    Directory of Open Access Journals (Sweden)

    Oleg Meshcheryakov

    2010-01-01

    Full Text Available In humid air, the substantial charge-dipole attraction and electrostatic acceleration of surrounding water vapour molecules towards charged combustible nanoparticles cause intense electrostatic hydration and preferential oxidation of these nanoparticles by electrostatically accelerated polar water vapour molecules rather than nonaccelerated nonpolar oxygen gas molecules. Intense electrostatic hydration of charged combustible nanoparticles converts the nanoparticle's oxide-based shells into the hydroxide-based electrolyte shells, transforming these nanoparticles into reductant/air core-shell nanobatteries, periodically short-circuited by intraparticle field and thermionic emission. Partially synchronized electron emission breakdowns within trillions of nanoparticles-nanobatteries turn a cloud of charged nanoparticles-nanobatteries into a powerful radiofrequency aerosol generator. Electrostatic oxidative hydration and charge-catalyzed oxidation of charged combustible nanoparticles also contribute to a self-oscillating thermocycling process of evolution and periodic autoignition of inflammable gases near to the nanoparticle's surface. The described effects might be of interest for the improvement of certain nanotechnological heterophase processes and to better understand ball lightning phenomenon.

  3. Device Rotates Bearing Balls For Inspection

    Science.gov (United States)

    Burley, R. K.

    1988-01-01

    Entire surface of ball inspected automatically and quickly. Device holds and rotates bearing ball for inspection by optical or mechanical surface-quality probe, eddy-current probe for detection of surface or subsurface defects, or circumference-measuring tool. Ensures entire surface of ball moves past inspection head quickly. New device saves time and increases reliability of inspections of spherical surfaces. Simple to operate and provides quick and easy access for loading and unloading of balls during inspection.

  4. Reflections on a Disco Ball

    Science.gov (United States)

    Ribeiro, Jair Lúcio Prados

    2016-01-01

    A disco ball is a spherical object covered with small plane mirrors. When light reflects on these mirrors, it is scattered in many directions, producing a novel effect. The mirror globe is usually set to rotate, creating a profusion of moving spots (Fig. 1). In this article, we present a geometrical description of the movement of these spots and…

  5. LHC gets the ball rolling

    CERN Document Server

    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.

  6. Eddy-Current Inspection of Ball Bearings

    Science.gov (United States)

    Bankston, B.

    1985-01-01

    Custom eddy-current probe locates surface anomalies. Low friction air cushion within cone allows ball to roll easily. Eddy current probe reliably detects surface and near-surface cracks, voids, and material anomalies in bearing balls or other spherical objects. Defects in ball surface detected by probe displayed on CRT and recorded on strip-chart recorder.

  7. Free-floating atmospheric pressure ball plasmas

    Science.gov (United States)

    Wurden, G. A.; Ticos, C.; Wang, Z.; Wurden, C. J. V.

    2007-11-01

    A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with a weak solution of various salts in distilled water, such as CuSO4 or CuCl2, LiCl or NaCl). An underwater ring anode completes the circuit. A bubble of hot vapor from the water surface rises up in the first few milliseconds, and changes from a mushroom cloud with stalk, to a detached quasi-spherical object, finally evolving into a vortex ring. The plasma consists of ionized water vapor, with positive salts and OH- radicals, as well as molecular species, and it completely excludes nitrogen or oxygen from the rising plasma structure. A fine boundary layer is visible in orange, in contrast to a green ball interior when using Cu/CuSO4, and filamentary structures are visible at late times. Finally, a whisp of smoke ring is observed as a residue. A variety of visible and infrared imaging (both video and still cameras) are used, along with 200-800 nm time & space resolved spectroscopy, to identify features of this laboratory analog to ball lightning. Possible applications include a windowless ball- plasma powered pulsed copper vapor laser operating at 510 nm.

  8. Investigation of a Plasma Ball using a High Speed Camera

    Science.gov (United States)

    Laird, James; Zweben, Stewart; Raitses, Yevgeny; Zwicker, Andrew; Kaganovich, Igor

    2008-11-01

    The physics of how a plasma ball works is not clearly understood. A plasma ball is a commercial ``toy'' in which a center electrode is charged to a high voltage and lightning-like discharges fill the ball with many plasma filaments. The ball uses high voltage applied on the center electrode (˜5 kV) which is covered with glass and capacitively coupled to the plasma filaments. This voltage oscillates at a frequency of ˜26 kHz. A Nebula plasma ball from Edmund Scientific was filmed with a Phantom v7.3 camera, which can operate at speeds up to 150,000 frames per second (fps) with a limit of >=2 μsec exposure per frame. At 100,000 fps the filaments were only visible for ˜5 μsec every ˜40 μsec. When the plasma ball is first switched on, the filaments formed only after ˜800 μsec and initially had a much larger diameter with more chaotic behavior than when the ball reached its final plasma filament state at ˜30 msec. Measurements are also being made of the final filament diameter, the speed of the filament propagation, and the effect of thermal gradients on the filament density. An attempt will be made to explain these results from plasma theory and movies of these filaments will be shown. Possible theoretical models include streamer-like formation, thermal condensation instability, and dielectric barrier discharge instability.

  9. Improvements of condenser performance with granulate balls

    International Nuclear Information System (INIS)

    Bratthaell, L.

    1986-05-01

    At the nuclear power plant Oskarshamn has during time Nov 1983 - Apr 1985 test series been done to investigate the improvements of condensor performance with granulate balls. This type of ball is a normal sponge rubber ball coated with granulated plastic material. This material is, different from carborundum and pumice not abrasive to the tube material. The test results show that granulate balls give an improvement of the overall heat transfer coefficient of 5-7 percent compared to continous cleaning with normal sponge rubber balls. Granulate balls remove the utmost thin coating of organic material that the spong rubber balls are not able to remove and a practically metallic clean surface is established. This has been verified by laboratory inspection of tubes withdrawn from the tube bundle and site inspections of the condenser. When the condenser is cleaned by granulate balls during a period of about three days it is possible to keep the performance at a high level for a long time with continous cleaning with normal sponge rubber balls. After about three days the plastic layer on the balls is practically worned out. The balls have during that time fulfilled their function. The improvement in condenser temperature is 1,0-1,5 degree C. For the 02-turbine this means additional delivered energy of about 15000 MWh per year. (author)

  10. Ball mounting fixture for a roundness gage

    Science.gov (United States)

    Gauler, A.L.; Pasieka, D.F.

    1983-11-15

    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. 6 figs.

  11. 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

  12. Handel's Maser-Soliton Theory of ball lightning: The creation of stable three-dimensional cavitons by an atmospheric maser within an open resonator

    Science.gov (United States)

    Carlson, Glenn Andrew

    This dissertation develops details of Handel's Maser-Soliton Theory of ball lightning. The atmosphere between a thundercloud and the Earth's surface is modeled as an idealized stable open resonator with water vapor as the active medium and the thundercloud and Earth's surface as reflecting surfaces. The stable resonator generates a maser beam that narrows to the beam waist at the Earth's surface, which is assumed to be planar. Two candidate rotational transitions are identified within the ν1ν 2ν3 = 010 vibrational band of water having wavelengths of 13.9 cm and 1.12 cm, and relevant spectroscopic parameters are retrieved from the HITRAN 2008 molecular spectroscopic database. The maser is modeled as a continuously pumped four-level maser that includes the effects of nonradiative relaxation due to molecular collisions and of microwave absorption in atmospheric oxygen. Since maser spiking is highly unlikely to occur due to the high rate of collisional relaxation at normal atmospheric pressure, the electrical breakdown of air must be achieved by the steady state output of the atmospheric maser. A parametric analysis is performed to relate the size of the atmospheric maser to the pumping rate needed to create a steady state population inversion sufficient to generate maser radiation intense enough at the beam waist to result in the electrical breakdown of air. The analysis suggests that electric field intensities at the beam waist sufficient to cause electrical breakdown of air could only be created through huge pumping rates (˜105 to 107 times the critical pumping rate) and only for the most highly curved clouds (g ≈ 0) that give the narrowest beam waists.

  13. Measurements of drag and lift on smooth balls in flight

    Science.gov (United States)

    Cross, Rod; Lindsey, Crawford

    2017-07-01

    Measurements are presented on the drag and lift coefficients for three relatively smooth balls launched in air and tracked with two cameras separated horizontally by 6.4 m. The ball spin was varied in order to investigate whether the Magnus force would increase or decrease when the ball spin was increased. For one ball, the Magnus force increased. For another ball, the Magnus force decreased almost to zero after reaching a maximum. For the third ball, the Magnus force was negative at low ball spins and positive at high ball spins. For one of the balls, the ball spin increased with time as it travelled through the air.

  14. 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.

  15. Fluid Mechanics of Cricket and Tennis Balls

    Science.gov (United States)

    Mehta, Rabindra D.

    2009-11-01

    Aerodynamics plays a prominent role in defining the flight of a ball that is struck or thrown through the air in almost all ball sports. The main interest is in the fact that the ball can often deviate from its initial straight path, resulting in a curved, or sometimes an unpredictable, flight path. It is particularly fascinating that that not all the parameters that affect the flight of a ball are always under human influence. Lateral deflection in flight, commonly known as swing, swerve or curve, is well recognized in cricket and tennis. In tennis, the lateral deflection is produced by spinning the ball about an axis perpendicular to the line of flight, which gives rise to what is commonly known as the Magnus effect. It is now well recognized that the aerodynamics of sports balls are strongly dependent on the detailed development and behavior of the boundary layer on the ball's surface. A side force, which makes a ball curve through the air, can also be generated in the absence of the Magnus effect. In one of the cricket deliveries, the ball is released with the seam angled, which trips the laminar boundary layer into a turbulent state on that side. The turbulent boundary layer separates relatively late compared to the laminar layer on the other side, thereby creating a pressure difference and hence side force. The fluid mechanics of a cricket ball become very interesting at the higher Reynolds numbers and this will be discussed in detail. Of all the round sports balls, a tennis ball has the highest drag coefficient. This will be explained in terms of the contribution of the ``fuzz" drag and how that changes with Reynolds number and ball surface wear. It is particularly fascinating that, purely through historical accidents, small disturbances on the ball surface, such as the stitching on cricket balls and the felt cover on tennis balls are all about the right size to affect boundary layer transition and development in the Reynolds numbers of interest. The fluid

  16. 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.

  17. The Soccer-Ball Problem

    Science.gov (United States)

    Hossenfelder, Sabine

    2014-07-01

    The idea that Lorentz-symmetry in momentum space could be modified but still remain observer-independent has received quite some attention in the recent years. This modified Lorentz-symmetry, which has been argued to arise in Loop Quantum Gravity, is being used as a phenomenological model to test possibly observable effects of quantum gravity. The most pressing problem in these models is the treatment of multi-particle states, known as the 'soccer-ball problem'. This article briefly reviews the problem and the status of existing solution attempts.

  18. Crystal ball data acquisition system

    International Nuclear Information System (INIS)

    Chestnut, R.; Kiesling, C.; Bloom, E.; Bulos, F.; Gaiser, J.; Godfrey, G.; Oreglia, M.; Partridge, R.; Peck, C.; Porter, F.; Aschman, D.; Cavali-Sforza, M.; Coyne, D.; Sadrozinski, H.; Kollmann, W.; Richardson, M.

    1979-01-01

    The data acquisition system for the Crystal Ball project at SLAC is described. A PDP-11/t55 using RSX-11M connected to the SLAC Triplex is the basis of the system. A ''physics pipeline'' allows physicists to write their own equipment-monitoring or physics tasks which require event sampling. As well, an interactive analysis package (MULTI) is in the pipeline. Histogram collection and display on the PDP are implemented using the Triplex histogramming package. Various interactive event displays are also implemented

  19. 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

  20. A Comparative Study of Two Types of Ball-on-Ball Collision

    Science.gov (United States)

    White, Colin

    2017-01-01

    This paper describes three methods of measuring the coefficient of restitution (CoR) for two different types of ball-on-ball collision. The first collision type (for which two different CoR measurement procedures are described) is a static, hanging steel ball forming part of a Newton's cradle arrangement, which is then hit by its adjacent…

  1. 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

  2. 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…

  3. Protecting a Ball-Bearing-Deflection Monitor

    Science.gov (United States)

    Kuhr, George A.

    1987-01-01

    Deflectometer probe monitors deflection of ball-bearing race in liquid oxygen with aid of small window or diaphragm. Diaphragm or window isolates optical deflectometer from liquid oxygen or other fluid in ball bearing. At high pressures, diaphragm integral part of housing preferable to window, since there would be no leakage.

  4. Flicker Ball, Physical Education: 5551.34.

    Science.gov (United States)

    Stout, Paul L.

    This course outline is a guide for teaching skills of flicker ball in grades 7-12. The course format includes lectures, game situations, class tournaments, and tests that focus on mastery of skills, understanding of rules, and development of techniques in shooting and passing. Course content includes the following: (a) history of flicker ball, (b)…

  5. The principal time balls of New Zealand

    Science.gov (United States)

    Kinns, Roger

    2017-04-01

    Accurate time signals in New Zealand were important for navigation in the Pacific. Time balls at Wellington and Lyttelton were noted in the 1880 Admiralty list of time signals, with later addition of Otago. The time ball service at Wellington started in March 1864 using the first official observatory in New Zealand, but there was no Wellington time ball service during a long period of waterfront redevelopment during the 1880s. The time ball service restarted in November 1888 at a different harbour location. The original mechanical apparatus was used with a new ball, but the system was destroyed by fire in March 1909 and was never replaced. Instead, a time light service was inaugurated in 1912. The service at Lyttelton, near Christchurch, began in December 1876 after construction of the signal station there. It used telegraph signals from Wellington to regulate the time ball. By the end of 1909, it was the only official time ball in New Zealand, providing a service that lasted until 1934. The Lyttelton time ball tower was an iconic landmark in New Zealand that had been carefully restored. Tragically, the tower collapsed in the 2011 earthquakes and aftershocks that devastated Christchurch. A daily time ball service at Port Chalmers, near Dunedin, started in June 1867, initially using local observatory facilities. The service appears to have been discontinued in October 1877, but was re-established in April 1882 as a weekly service, with control by telegraph from Wellington. The service had been withdrawn altogether by the end of 1909. Auckland never established a reliable time ball service, despite provision of a weekly service for mariners by a public-spirited citizen between August 1864 and June 1866. A time ball was finally installed on the Harbour Board building in 1901, but the signal was unreliable and it ceased in 1902. Complaints from ships' masters led to various proposals to re-establish a service. These concluded with erection of a time ball on the new

  6. 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.

  7. La balle et la plume

    Directory of Open Access Journals (Sweden)

    Peter Marquis

    2012-06-01

    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  8. Cricket Ball Aerodynamics: Myth Versus Science

    Science.gov (United States)

    Mehta, Rabindra D.; Koga, Demmis J. (Technical Monitor)

    2000-01-01

    Aerodynamics plays a prominent role in the flight of a cricket ball released by a bowler. The main interest is in the fact that the ball can follow a curved flight path that is not always under the control of the bowler. ne basic aerodynamic principles responsible for the nonlinear flight or "swing" of a cricket ball were identified several years ago and many papers have been published on the subject. In the last 20 years or so, several experimental investigations have been conducted on cricket ball swing, which revealed the amount of attainable swing, and the parameters that affect it. A general overview of these findings is presented with emphasis on the concept of late swing and the effects of meteorological conditions on swing. In addition, the relatively new concept of "reverse" swing, how it can be achieved in practice and the role in it of ball "tampering", are discussed in detail. A discussion of the "white" cricket ball used in last year's World Cup, which supposedly possesses different swing properties compared to a conventional red ball, is also presented.

  9. 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.

  10. The ball SITE sign: Ball sports-induced targetoid erythema in a racquetball player.

    Science.gov (United States)

    Cohen, Philip R

    2015-07-01

    Cutaneous injury following impact of a high velocity ball to the skin may result in either erythema or purpura or both. The lesion typically appears as an annular ring of erythema with or without accompanying ecchymosis when the skin is contacted by a paintball, a ping pong ball, a racquetball or a squash ball. To describe a girl with targetoid erythema following impact of a racquetball on her flank and back and to review other sports associated with this response to skin injury. PubMed was used to search the following terms, separately and in combination: ball, erythema, paint, ping pong, purpura, racquetball, sign, site, sports, squash, targetoid. All papers were reviewed and relevant manuscripts, along with their reference citations, were evaluated. A 13-year-old girl developed an annular red ring surrounding a central area of normal appearing skin on her right flank and upper back where a racquetball traveling at a high velocity contacted her skin. Similar appearing lesions of targetoid erythema have been described at the cutaneous impact sites of either paintballs, ping pong balls, squash balls; in addition to erythema, purpura may also concurrently appear or subsequently develop at the contact location of the ball with the skin. Targetoid erythema is a pathognomonic cutaneous presentation resulting from the impact of either a paintball, ping pong ball, racquetball or squash ball-that is traveling at a high velocity-with a sport participant's skin. The ball SITE (sports-induced targetoid erythema) sign is suggested as a unifying nomenclature to designate this unique, ball sport-associated, cutaneous dermatosis in athletes participating in sports in which high velocity impact of the ball with the skin may occur.

  11. How Magnus Bends the Flying Ball--Experimenting and Modeling

    Science.gov (United States)

    Timková, V.; Ješková, Z.

    2017-01-01

    Students are well aware of the effect of the deflection of sports balls when they have been given a spin. A volleyball, tennis, or table tennis ball served with topspin results in an additional downward force that makes the ball difficult to catch and return. In soccer, the effect of sidespin causes the ball to curve unexpectedly sideways,…

  12. Flexible timing of eye movements when catching a ball.

    Science.gov (United States)

    López-Moliner, Joan; Brenner, Eli

    2016-01-01

    In ball games, one cannot direct ones gaze at the ball all the time because one must also judge other aspects of the game, such as other players' positions. We wanted to know whether there are times at which obtaining information about the ball is particularly beneficial for catching it. We recently found that people could catch successfully if they saw any part of the ball's flight except the very end, when sensory-motor delays make it impossible to use new information. Nevertheless, there may be a preferred time to see the ball. We examined when six catchers would choose to look at the ball if they had to both catch the ball and find out what to do with it while the ball was approaching. A catcher and a thrower continuously threw a ball back and forth. We recorded their hand movements, the catcher's eye movements, and the ball's path. While the ball was approaching the catcher, information was provided on a screen about how the catcher should throw the ball back to the thrower (its peak height). This information disappeared just before the catcher caught the ball. Initially there was a slight tendency to look at the ball before looking at the screen but, later, most catchers tended to look at the screen before looking at the ball. Rather than being particularly eager to see the ball at a certain time, people appear to adjust their eye movements to the combined requirements of the task.

  13. 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.

  14. Crystal ball single event display

    International Nuclear Information System (INIS)

    Grosnick, D.; Gibson, A.; Allgower, C.; Alyea, J.; Argonne National Lab., IL

    1997-01-01

    The Single Event Display (SED) is a routine that is designed to provide information graphically about a triggered event within the Crystal Ball. The SED is written entirely in FORTRAN and uses the CERN-based HICZ graphing package. The primary display shows the amount of energy deposited in each of the NaI crystals on a Mercator-like projection of the crystals. Ten different shades and colors correspond to varying amounts of energy deposited within a crystal. Information about energy clusters is displayed on the crystal map by outlining in red the thirteen (or twelve) crystals contained within a cluster and assigning each cluster a number. Additional information about energy clusters is provided in a series of boxes containing useful data about the energy distribution among the crystals within the cluster. Other information shown on the event display include the event trigger type and data about π o 's and η's formed from pairs of clusters as found by the analyzer. A description of the major features is given, along with some information on how to install the SED into the analyzer

  15. Middle finger and ball movements around ball release during baseball fastball pitching.

    Science.gov (United States)

    Matsuo, Tomoyuki; Jinji, Tsutomu; Hirayama, Daisaku; Nasu, Daiki; Ozaki, Hiroki; Kumagawa, Daisuke

    2017-02-28

    The objectives of this study were to investigate middle finger movements and dynamics of ball movements around the instant of ball release during baseball pitching. Baseball pitching from an indoor mound among 14 semi-professional pitchers was captured using a motion capture system with 16 high-speed cameras (1,000 Hz). Kinematics of middle finger joints, ball rotation, and force applied to the ball were calculated. The proximal and distal interphalangeal joints continued to extend until the instant of ball release, then abruptly flexed. The abrupt flexion lasted for only several milliseconds, followed by a short extension phase. The finger made a quick double cycle of extension-flexion movement, suggesting that it attained high stiffness resulting from co-contraction. The ball began to roll up to the tip of the finger 8 ± 1 ms before ball release owing to the start of extension or the increased angular velocity of extension for the proximal interphalangeal joint. A mean force of 195 ± 27 N was applied in the proximal direction of the hand at the same time as the beginning of ball rolling, and a mean force of 109 ± 22 N was applied to the throwing direction just before ball release.

  16. 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.

  17. 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.

  18. Effects of bushings characteristics on suspension ball joint travels

    Science.gov (United States)

    Yang, Xiaobo

    2011-02-01

    In this paper, a short-long arm type front suspension is represented using multi-body dynamics model established with ADAMS®, where the suspension bushings modelled as linear and nonlinear elements, respectively, are integrated with a flexible cradle and other suspension components. A ball joint travel, defined as the angular displacement between the two parts connected with the ball joint, is calculated, where the measured wheel loads and spindle accelerations from a proving ground severe durability test schedule serve as the input data. The ball joints considered in this study include lower ball joints, upper ball joints, outer tierod ball joints, and inner tierod ball joints. The results clearly illustrate that the bushing stiffness and nonlinearity are important for an accurate prediction of ball joint travels and the ball joint travel sensitivities to considered design variables are important for engineers to understand and ensure reliable designs of ball joints.

  19. 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

  20. Keeping Your Eyes Continuously on the Ball While Running for Catchable and Uncatchable Fly Balls

    NARCIS (Netherlands)

    Postma, Dees B. W.; den Otter, A. Rob; Zaal, Frank T. J. M.

    2014-01-01

    When faced with a fly ball approaching along the sagittal plane, fielders need information for the control of their running to the interception location. This information could be available in the initial part of the ball trajectory, such that the interception location can be predicted from its

  1. 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.

  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. Novel mathematical model to estimate ball impact force in soccer.

    Science.gov (United States)

    Iga, Takahito; Nunome, Hiroyuki; Sano, Shinya; Sato, Nahoko; Ikegami, Yasuo

    2017-11-22

    To assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of 'footballer's ankle'. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view.

  4. 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.

  5. 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.

  6. Soccer ball lift coefficients via trajectory analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goff, John Eric [Department of Physics, Lynchburg College, Lynchburg, VA 24501 (United States); Carre, Matt J, E-mail: goff@lynchburg.ed [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2010-07-15

    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 parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.

  7. Paddle Angle and Ball Spin in Table Tennis

    Directory of Open Access Journals (Sweden)

    Binvant Broca

    2017-01-01

    Full Text Available The relationship between the impact angle of a table tennis ball with respect to the paddle and angular velocity of the ball leaving the paddle was investigated. A table tennis ball was dropped onto a paddle oriented at impact angles ranging from 10° to 80°. It was found that the sine of the impact angle is proportional to the angular velocity of the ball as it leaves the paddle for all impact angles tested.

  8. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  9. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    theory of computation, logic, and linear algebra. He has authored three books in these areas. We present a ball game that can be continued as long as we wish. It looks as though the game would never end. But by applying a result on trees, we show that the game nonetheless ends in some finite number of moves. We then ...

  10. On the dynamics of ball bearings

    NARCIS (Netherlands)

    Wensing, J.A.

    1998-01-01

    This investigation on the dynamic behaviour of ball bearings was motivated by the demand for silent bearings in noise-sensitive applications, especially in the household appliance and automotive industry. The present investigations are intended to provide a clear understanding of the role of the

  11. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    We present a ball game that can be continued as long as wewish. It looks as though the game would never end. But byapplying a result on trees, we show that the game nonethelessends in some finite number of moves. We then point out somedeep results on the natural number system connected withthe game.

  12. Computed Tomography Analysis of NASA BSTRA Balls

    Energy Technology Data Exchange (ETDEWEB)

    Perry, R L; Schneberk, D J; Thompson, R R

    2004-10-12

    Fifteen 1.25 inch BSTRA balls were scanned with the high energy computed tomography system at LLNL. This system has a resolution limit of approximately 210 microns. A threshold of 238 microns (two voxels) was used, and no anomalies at or greater than this were observed.

  13. Renal fungus ball: a challenging clinical problem.

    Science.gov (United States)

    Tan, Wei Phin; Turba, Ulku C; Deane, Leslie A

    2017-04-28

    We describe a case of renal pelvi-ureteric fungus ball managed with placement of two nephrostomy tubes and amphotericin B irrigation through a nephrostomy tube with the other to free drain. A 46-year-old man with uncontrolled Type 2 diabetes mellitus was referred to the urology clinic for workup of recurrent urinary tract infection. Urine culture grew Candida albicans. The patient was started on oral fluconazole therapy. Cystoscopy and cystogram revealed a grade 3 left vesicoureteral reflux and right retrograde pyelogram revealed a filling defect in the right renal pelvis extending into the proximal ureter with severe hydroureteronephrosis. Two nephrostomy tubes were placed (mid-pole and lower pole) to ensure that the system was not obstructed. Amphotericin B (50 mg/1000 ml normal saline) irrigation was then instilled through the mid-pole nephrostomy tube at a rate of 30 ml/h with the lower pole nephrostomy tube to free drain. An antegrade nephrostogram was performed after 5 days of amphotericin B instillation, showing complete resolution of the fungus ball. The patient is awaiting definitive minimally invasive management of the distal ureteral narrowing. Renal and pelvi-ureteric fungus ball is a challenging clinical entity. It must be addressed promptly and efficiently to be successful. We describe a minimally invasive approach that was tolerated well and resulted in complete clearance of the fungus ball in a relatively short time frame.

  14. 4 π physics with the plastic ball

    International Nuclear Information System (INIS)

    Gutbrod, H.H.; Loehner, H.; Poskanzer, A.M.; Renner, T.; Riedesel, H.; Ritter, H.G.; Warwick, A.; Weik, F.; Wieman, H.

    1982-10-01

    4 π data taken with the Plastic Ball show that cluster production in relativistic nuclear collisions depends on both the size of the participant volume and the finite size of the cluster. The measurement of the degree of thermalization and the search for collective flow will permit the study of the applicability of macroscopic concepts such as temperature and density

  15. Tennis Ball Flight under Strong Wind

    Indian Academy of Sciences (India)

    playing tennis ball cricket or soccer. So go out, play, learn and kick up some dust. But, make sure it does not boomerang in your face! Hurry up before television and third umpires corrupt this great IndIan pastime. Dedication: This article is dedicated to the memory of. Indian cricket legend M L Jaisimha (1939-1999).

  16. A plasma ball in the Microcosm museum

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Plasma balls, like the one shown here, are displayed in the Microcosm exhibition where families can visit to learn more about the experiments carried out in a research institute like CERN. Hands-on activities allow visitors to get a step closer to the research activities carried out at CERN.

  17. Entry Times Distribution for Dynamical Balls on Metric Spaces

    Science.gov (United States)

    Haydn, N.; Yang, F.

    2017-04-01

    We show that the entry and return times for dynamical balls (Bowen balls) is exponential for systems that have an α -mixing invariant measure with certain regularities. We also show that systems modeled by Young's tower has exponential entry time distribution for dynamical balls. We also apply the results to conformal maps and expanding maps on the interval.

  18. Flexible timing of eye movements when catching a ball

    NARCIS (Netherlands)

    López-Moliner, Joan; Brenner, Eli

    2016-01-01

    In ball games, one cannot direct ones gaze at the ball all the time because one must also judge other aspects of the game, such as other players' positions. We wanted to know whether there are times at which obtaining information about the ball is particularly beneficial for catching it. We recently

  19. Temperature and Coefficient of Restitution of a Table Tennis Ball

    Directory of Open Access Journals (Sweden)

    Yoonyoung Chang

    2016-01-01

    Full Text Available The coefficient of restitution (COR of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  20. 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…

  1. Temperature and Coefficient of Restitution of a Table Tennis Ball

    OpenAIRE

    Yoonyoung Chang

    2016-01-01

    The coefficient of restitution (COR) of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  2. 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

  3. Ball Lightning–Aerosol Electrochemical Power Source or A Cloud of Batteries

    Science.gov (United States)

    2007-01-01

    Despite numerous attempts, an adequate theoretical and experimental simulation of ball lightning still remains incomplete. According to the model proposed here, the processes of electrochemical oxidation within separate aerosol particles are the basis for this phenomenon, and ball lightning is a cloud of composite nano or submicron particles, where each particle is a spontaneously formed nanobattery which is short-circuited by the surface discharge because it is of such a small size. As free discharge-shorted current loops, aerosol nanobatteries are exposed to a powerful mutual magnetic dipole–dipole attraction. The gaseous products and thermal energy produced by each nanobattery as a result of the intra-particle self-sustaining electrochemical reactions, cause a mutual repulsion of these particles over short distances and prevent their aggregation, while a collectivization of the current loops of separate particles, due to the electric arc overlapping between adjacent particles, weakens their mutual magnetic attraction over short distances. Discharge currents in the range of several amperes to several thousand amperes as well as the pre-explosive mega ampere currents, generated in the reduction–oxidation reactions and distributed between all the aerosol particles, explain both the magnetic attraction between the elements of the ball lightning substance and the impressive electromagnetic effects of ball lightning.

  4. Ball Lightning–Aerosol Electrochemical Power Source or A Cloud of Batteries

    Directory of Open Access Journals (Sweden)

    Meshcheryakov Oleg

    2007-01-01

    Full Text Available AbstractDespite numerous attempts, an adequate theoretical and experimental simulation of ball lightning still remains incomplete. According to the model proposed here, the processes of electrochemical oxidation within separate aerosol particles are the basis for this phenomenon, and ball lightning is a cloud of composite nano or submicron particles, where each particle is a spontaneously formed nanobattery which is short-circuited by the surface discharge because it is of such a small size. As free discharge-shorted current loops, aerosol nanobatteries are exposed to a powerful mutual magnetic dipole–dipole attraction. The gaseous products and thermal energy produced by each nanobattery as a result of the intra-particle self-sustaining electrochemical reactions, cause a mutual repulsion of these particles over short distances and prevent their aggregation, while a collectivization of the current loops of separate particles, due to the electric arc overlapping between adjacent particles, weakens their mutual magnetic attraction over short distances. Discharge currents in the range of several amperes to several thousand amperes as well as the pre-explosive mega ampere currents, generated in the reduction–oxidation reactions and distributed between all the aerosol particles, explain both the magnetic attraction between the elements of the ball lightning substance and the impressive electromagnetic effects of ball lightning.

  5. Apparatus and method for inspecting a bearing ball

    Science.gov (United States)

    Bankston, B. F. (Inventor)

    1985-01-01

    A method and apparatus for inspecting the surface of a ball bearing is disclosed which includes a base having a high friction non-abrasive base scanning surface. A holding device includes a cone-shaped cup recess in which a ball element is received. Air is introduced through a passage to relieve friction between the wall of the recess and the ball element and facilitate rolling of the ball over the high friction base surface. The holding device is moved over the base scanning surface in a predetermined pattern such that the entire surface of the ball element is inspected byan eddy current probe which detects any surface defects.

  6. Aerodynamic effects of dimples on soccer ball surfaces.

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2017-10-01

    Recently, the shape and design of the panel on the official ball used in the FIFA World Cup was considerably different from that of a conventional soccer ball (having 32 pentagonal and hexagonal panels). Depending on the number of different panels and their orientation, the aerodynamic force experienced by a ball is believed to change, which in turn changes the ball trajectory. However, not much is known about the impact of the surface forms of a ball on its aerodynamics. Therefore, in the present study, 10 different types of soccer balls were produced and their aerodynamic properties were studied by wind tunnel experiments. The results confirmed that the aerodynamic force acting on the ball varied considerably depending on the existence of dimples on the ball surface. In addition, the 4 types of soccer balls, which had different kinds of roughness, revealed that even balls having the same number and shapes of panels experienced greatly varying aerodynamic forces depending on the surface form of the balls.

  7. The strange flight behaviour of slowly spinning soccer balls

    Science.gov (United States)

    Mizota, Taketo; Kurogi, Kouhei; Ohya, Yuji; Okajima, Atsushi; Naruo, Takeshi; Kawamura, Yoshiyuki

    2013-05-01

    The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.

  8. Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

    Directory of Open Access Journals (Sweden)

    Jan Carboch, Vladimir Süss, Tomas Kocib

    2014-06-01

    Full Text Available Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server. Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing.

  9. 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.

  10. From a Ball Game to Incompleteness

    Indian Academy of Sciences (India)

    tree is a tree in which each node has a finite number of children. In a rooted tree, the sequence of nodes from the root to a leaf, where the (j + 1)th node is a child of the jth node, is called a. 'path'. For instance, in the above tree, the root contains 2, and all leafs are the nodes that contain 0. Since any ball is replaced with a fi-.

  11. Testing general relativity using a bouncing ball

    Directory of Open Access Journals (Sweden)

    Shiuan-Ni Liang

    2014-01-01

    Full Text Available In a recent article (Liang and Lan, (2011, we showed that the trajectories predicted by general-relativistic and Newtonian mechanics from the same parameters and initial conditions for a low-speed weak-gravity bouncing ball system will rapidly disagree completely if the trajectories are chaotic. Here, we determine how accurate the parameters and initial conditions of the system must be known so that the two different calculated chaotic trajectories are sufficiently accurate for an empirical test.

  12. Ball-thrower's fracture of the humerus

    International Nuclear Information System (INIS)

    Callaghan, Eric B.; Bennett, D. Lee; El-Khoury, Georges Y.; Ohashi, Kenjirou

    2004-01-01

    A relatively rare case of ball-thrower's fracture of the humerus is presented. Severe muscular action is an uncommon cause of humeral fractures but has been well documented in the orthopedic literature. To our knowledge, this fracture has not been described in the radiology literature, and awareness of this entity could preclude further unnecessary workup. The mechanism of injury and its typical radiographic appearance is described. (orig.)

  13. Effect of Changing Table Tennis Ball Material from Celluloid to Plastic on the Post-Collision Ball Trajectory

    Directory of Open Access Journals (Sweden)

    Inaba Yuki

    2017-01-01

    Full Text Available The official material used in table tennis balls was changed from celluloid to plastic, a material free of celluloid, in 2014. The purpose of this study was to understand the differences and similarities in the two types of ball materials by comparing their behavior upon collision with a table. The behavior of the balls before and after collision with a table, at various initial speeds ranging from 15 to 115 km/h, was captured using high-speed cameras. Velocities and spin rates before collision and velocities after collision were computed to calculate the coefficients of restitution and friction. Based on the computed variables, the post-collision trajectories of both balls were calculated by integrating the equation of motion of the ball for simulated service, smash and drive conditions with respect to time. The coefficients of restitution were higher for the plastic balls than the celluloid ones when the initial vertical velocities were higher. The coefficients of friction were higher for plastic balls when the initial horizontal contact point velocities were slower. Because of the differences in the material characteristics, the plastic ball trajectories of services with backspin and drives with great topspin were expected to be different from those of celluloid balls. Since the extent of differences between the two ball types varied depending on the initial conditions, testing at various initial conditions was suggested for comparing and understanding the characteristics of the balls.

  14. Effect of Changing Table Tennis Ball Material from Celluloid to Plastic on the Post-Collision Ball Trajectory.

    Science.gov (United States)

    Inaba, Yuki; Tamaki, Sho; Ikebukuro, Haruhiko; Yamada, Koshi; Ozaki, Hiroki; Yoshida, Kazuto

    2017-01-01

    The official material used in table tennis balls was changed from celluloid to plastic, a material free of celluloid, in 2014. The purpose of this study was to understand the differences and similarities in the two types of ball materials by comparing their behavior upon collision with a table. The behavior of the balls before and after collision with a table, at various initial speeds ranging from 15 to 115 km/h, was captured using high-speed cameras. Velocities and spin rates before collision and velocities after collision were computed to calculate the coefficients of restitution and friction. Based on the computed variables, the post-collision trajectories of both balls were calculated by integrating the equation of motion of the ball for simulated service, smash and drive conditions with respect to time. The coefficients of restitution were higher for the plastic balls than the celluloid ones when the initial vertical velocities were higher. The coefficients of friction were higher for plastic balls when the initial horizontal contact point velocities were slower. Because of the differences in the material characteristics, the plastic ball trajectories of services with backspin and drives with great topspin were expected to be different from those of celluloid balls. Since the extent of differences between the two ball types varied depending on the initial conditions, testing at various initial conditions was suggested for comparing and understanding the characteristics of the balls.

  15. 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.

  16. Searching for Q-balls with HAWC

    Science.gov (United States)

    Karn, Peter

    2013-04-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a gamma-ray experiment currently under construction at Sierra Negra in the state of Puebla, Mexico. Once completed, it will consist of a 20,000 square meter array of 300 water Cherenkov detectors. Although the HAWC Observatory is designed to study gamma rays from galactic and extra-galactic sources, the large instrumented volume of water gives the opportunity to search for more exotic species. One such target, predicted by several varieties of supersymmetric theory, is the Q-ball. Q-balls are very massive, sub-relativistic particles that can have a large baryon number, and can be stable since their creation in the early universe. They are also an appealing candidate for the dark matter of the universe, but their large masses must mean that their flux is very low. The data acquisition system of the HAWC Observatory is flexible enough that, with a dedicated trigger algorithm for non-relativistic particles, it allows the search for Q-balls traversing the detector. The trigger algorithm and preliminary analysis will be presented.

  17. 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

  18. Modeling on the Effect of Coal Loads on Kinetic Energy of Balls for Ball Mills

    Directory of Open Access Journals (Sweden)

    Yan Bai

    2015-07-01

    Full Text Available This paper presents a solution for the detection and control of coal loads that is more accurate and convenient than those currently used. To date, no research has addressed the use of a grinding medium as the controlled parameter. To improve the accuracy of the coal load detection based on the kinetic energy of balls in a tubular ball mill, a Discrete Element Method (DEM model for ball kinematics based on coal loads is proposed. The operating process for a ball mill and the ball motion, as influenced by the coal quality and the coal load, was analyzed carefully. The relationship between the operating efficiency of a coal pulverizing system, coal loads, and the balls’ kinetic energy was obtained. Origin and Matlab were utilized to draw the variation of parameters with increasing coal loads in the projectile and cascading motion states. The parameters include the balls’ real-time kinetic energy, the friction energy consumption, and the mill’s total work. Meanwhile, a method of balanced adjacent degree and a physical experiment were proposed to verify the considerable effect of the balls’ kinetic energy on coal loads. The model and experiment results indicate that a coal load control method based on the balls’ kinetic energy is therefore feasible for the optimized operation of a coal pulverizing system.

  19. The nonlinear and ball pass effects of a ball bearing on rotor vibration

    International Nuclear Information System (INIS)

    Han, D. C.; Choi, S. H.; Lee, Y. H.; Kim, K. H.

    1998-01-01

    A ball bearing is generally assumed as a linear spring in rotor dynamic analysis. In real case, the force equilibrium of the bearing is changed as the relative position of each ball with respect to the direction of radial force. So, the stiffness of the bearing is also changed and is a function of time and position. In this study, the nonlinear characteristics of a ball bearing are considered in analyzing the vibration response of a rotating shaft due to an unbalance force. A finite element method is used to analyze the vibration characteristics of a rotor-bearing system and a direct numerical integration is performed to calculate the transient response of the rotor system. The responses are converted to the frequency domain and the effects of the parametric excitation due to a ball bearing are examined. The test rig for the investigation of the effect of a ball bearing on the rotor vibration is set up and the results are compared with those of numerical calculation. The calculation results show that the amplitudes of the nonlinear model are larger than those of the linear one. The frequencies of the calculations can be matched to the measured frequencies

  20. 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.

  1. Sitting on stability balls: biomechanics evaluation in a workplace setting.

    Science.gov (United States)

    Schult, Tamara M; Awosika, Ebi R; Schmunk, Sandra K; Hodgson, Michael J; Heymach, Bria L; Parker, Celestine Dent

    2013-01-01

    Use of a stability ball alone and stability ball chair were evaluated in the Veterans Health Administration as possible alternatives to incorporate with regular office chair use. The evaluation of stability ball use was conducted under the auspices of a work site health promotion program as a cross-over trial with participants rotating through use of the stability ball, stability ball chair, and regular office chair on a monthly basis for a total duration of 3 months. Rotations on regular office chairs served as the control. Three medical facilities participated. A total of 193 employees completed a baseline questionnaire; 159 completed at least one post-rotation questionnaire. Self-reported measures included perceived posture when sitting, perceptions of overall balance, energy levels, job performance, safety, and pain. Use was associated with improvements in perceived posture (p balance (p = 0.05) for stability ball chair users compared with the control. Use of stability balls at work decreases the likelihood of reporting pain from regular office chair use from approximately 45% to 21%. Alternatively, a high number of participants reported pain with use of the stability ball alone and stability ball chair, 42% and 45%, respectively. The perceived risks and benefits of stability ball use should be weighed when incorporating use.

  2. 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.

  3. Automatic ball bar for a coordinate measuring machine

    Science.gov (United States)

    Jostlein, Hans

    1997-01-01

    An automatic ball bar for a coordinate measuring machine determines the accuracy of a coordinate measuring machine having at least one servo drive. The apparatus comprises a first and second gauge ball connected by a telescoping rigid member. The rigid member includes a switch such that inward radial movement of the second gauge ball relative to the first gauge ball causes activation of the switch. The first gauge ball is secured in a first magnetic socket assembly in order to maintain the first gauge ball at a fixed location with respect to the coordinate measuring machine. A second magnetic socket assembly secures the second gauge ball to the arm or probe holder of the coordinate measuring machine. The second gauge ball is then directed by the coordinate measuring machine to move radially inward from a point just beyond the length of the ball bar until the switch is activated. Upon switch activation, the position of the coordinate measuring machine is determined and compared to known ball bar length such that the accuracy of the coordinate measuring machine can be determined.

  4. 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.

  5. Effect of Practicing Soccer Juggling With Different Sized Balls Upon Performance, Retention, and Transfer to Ball Reception.

    Science.gov (United States)

    Raastad, Olav; Aune, Tore Kristian; van den Tillaar, Roland

    2016-10-01

    The aim of this study was to investigate if making the skill acquisition phase more difficult or easier would enhance performance in soccer juggling, and if this practice has a positive intertask transfer effect to ball reception performance. Twenty-two adolescent soccer players were tested in juggling a soccer ball and in the control of an approaching ball at a pre, post and retention test. The participants were randomly divided in a small ball size and bigger ball size training group that both trained four times per week for 6 weeks. At the post and retention test both groups enhanced performance in soccer juggling test with no difference between groups and no increase in ball reception performance at these tests. It was concluded that about intra task transfer and retention of soccer juggling skills, it does not matter if you increase (small balls) or decrease the difficulty (larger balls) when using the same amount of practice time within the skill acquisition phase in soccer juggling. In addition that for ball juggling and ball reception (inter task) these two tasks differ too much in afferent information and movement characteristics that no positive transfer between these two skills no positive intertask transfer can be expected.

  6. The heads and tails of buoyant autocatalytic balls

    Science.gov (United States)

    Rogers, Michael C.; Morris, Stephen W.

    2012-09-01

    Buoyancy produced by autocatalytic reaction fronts can produce fluid flows that advect the front position, giving rise to interesting feedback between chemical and hydrodynamic effects. In this paper, we numerically investigate the evolution of autocatalytic iodate-arsenous acid reaction fronts initialized in spherical configurations. Deformation of these "autocatalytic balls" is driven by buoyancy produced by the reaction. In our simulations, we have found that depending on the initial ball radius, the reaction front will develop in one of three different ways. In an intermediate range of ball size, the flow can evolve much like an autocatalytic plume: the ball develops a reacting head and tail that is akin to the head and conduit of an autocatalytic plume. In the limit of large autocatalytic balls, however, growth of a reacting tail is suppressed and the resemblance to plumes disappears. Conversely, very small balls of product solution fail to initiate sustained fronts and eventually disappear.

  7. LOW COMPRESSION TENNIS BALLS AND SKILL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    John Hammond

    2006-12-01

    Full Text Available Coaching aims to improve player performance and coaches have a number of coaching methods and strategies they use to enhance this process. If new methods and ideas can be determined to improve player performance they will change coaching practices and processes. This study investigated the effects of using low compression balls (LCBs during coaching sessions with beginning tennis players. In order to assess the effectiveness of LCBs on skill learning the study employed a quasi-experimental design supported by qualitative and descriptive data. Beginner tennis players took part in coaching sessions, one group using the LCBs while the other group used standard tennis balls. Both groups were administered a skills at the beginning of a series of coaching sessions and again at the end. A statistical investigation of the difference between pre and post-test results was carried out to determine the effect of LCBs on skill learning. Additional qualitative data was obtained through interviews, video capture and the use of performance analysis of typical coaching sessions for each group. The skill test results indicated no difference in skill learning when comparing beginners using the LCBs to those using the standard balls. Coaches reported that the LCBs appeared to have a positive effect on technique development, including aspects of technique that are related to improving power of the shot. Additional benefits were that rallies went on longer and more opportunity for positive reinforcement. In order to provide a more conclusive answer to the effects of LCBs on skill learning and technique development recommendations for future research were established including a more controlled experimental environment and larger sample sizes across a longer period of time

  8. 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.

  9. Promoting ball skills in preschool-age girls.

    Science.gov (United States)

    Veldman, Sanne L C; Palmer, Kara K; Okely, Anthony D; Robinson, Leah E

    2017-01-01

    Evidence supports that girls are less proficient than boys at performing ball skills. This study examined the immediate and long-term effects of a ball skill intervention on preschool-age girls' ball skill performance. Randomized controlled trial. Girls (M age =47.24±7.38 months) were randomly assigned to a high autonomy, mastery-based 9-week motor skill intervention (the Children's Health Activity Motor Program; CHAMP, 540min; n=38) or a control group (free-play; n=16). Ball skill proficiency was assessed at pretest, posttest, and retention test (after 9 weeks) using the object control subscale of the Test of Gross Motor Development - 2nd Edition. Treatment efficacy was examined using linear mixed models. Two models were fit: one for short-term changes (pretest to posttest) and one for long-term changes (pretest to retention). Linear mixed models revealed a significantly time*treatment interaction for both models. Post hoc analysis confirmed that girls in CHAMP experienced significant gains in ball skills from pretest to posttest (p.05) but had significantly higher ball skills scores at both posttest (pball skill intervention (i.e., CHAMP) on improving girls' ball skills both short- and long-term. Findings suggest that early childhood interventions that focus on the development of ball skills in young girls might be an avenue to improve girls' ball skill performance. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. 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.

  11. Collective flow measured with the Plastic Ball

    International Nuclear Information System (INIS)

    Ritter, H.G.; Gutbrod, H.H.; Kampert, K.H.; Kolb, B.; Poskanzer, A.M.; Schicker, R.; Schmidt, H.R.; Siemiarczuk, T.

    1989-08-01

    The experimental results from the Plastic Ball detector have contributed vastly to the understanding of the reaction mechanism of nuclear collisions at several hundred MeV per nucleon. The discovery of the collective flow phenomena (bounce-off of spectator fragments, side-splash in the reaction plane, and squeeze-out out of the reaction plane), as they were predicted by hydrodynamical models, has led to the experimental observation of compressed nuclear matter, which is a necessary condition before one can study the equation of state in detail and search for phase transitions at higher energies. 39 refs., 9 figs., 1 tab

  12. Quenching simulation of steel grinding balls

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Hernandez, O.; Reyes, L. A.; Camurri, C.; Carrasco, C.; Garza-Monte-de-Oca, F.; Colas, R.

    2015-07-01

    The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses. (Author)

  13. 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).

  14. Ball Bearing Analysis with the ORBIS Tool

    Science.gov (United States)

    Halpin, Jacob D.

    2016-01-01

    Ball bearing design is critical to the success of aerospace mechanisms. Key bearing performance parameters, such as load capability, stiffness, torque, and life all depend on accurate determination of the internal load distribution. Hence, a good analytical bearing tool that provides both comprehensive capabilities and reliable results becomes a significant asset to the engineer. This paper introduces the ORBIS bearing tool. A discussion of key modeling assumptions and a technical overview is provided. Numerous validation studies and case studies using the ORBIS tool are presented. All results suggest the ORBIS code closely correlates to predictions on bearing internal load distributions, stiffness, deflection and stresses.

  15. Crystal Ball evidence for new states

    International Nuclear Information System (INIS)

    Coyne, D.G.

    1981-09-01

    Evidence for three new particles observed in the Crystal Ball detector is presented. The first particle, at 3592 MeV, is seen inclusively in γ transitions from psi', and is thus a candidate for eta/sub c/'. The other two, at 1440 and 1640 MeV, are best seen in exclusive decays of psi involving a prompt γ, and are thus candidates for bound states of two gluons. Detailed reasons are presented to support the contention that these states are distinct from previously observed candidates such as E(1420). Alternative hypotheses are discussed

  16. Tar ball Monitoring Along the Kenyan Beaches.

    OpenAIRE

    Nguta, M.

    1993-01-01

    Observations and measurements of petroleum tar balls on a number of Kenyan beaches were carried out between 1979 and 1982. A large variation in the size and amount of tar deposit at the beaches was recorded. These values ranged from very small pebbles to large lumps of 30 cm in diameter, weighing up to 1.5 kg. The average tar loading during the sampling period ranged from 0-18 g/m2. Between 25-50% by weight of the tar lumps were shell fragments, sand and other nonpetroleum debris. The chemica...

  17. RELATIONSHIP BETWEEN MEDICINE BALL EXPLOSIVE POWER TESTS, THROWING BALL VELOCITY AND JUMP PERFORMANCE IN TEAM HANDBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Mourad Fathloun

    2011-04-01

    Full Text Available In this study, the relationships between medicine ball explosive power tests, jump and handball throwing velocity performance in team handball players were investigated. Explosive test was measured by a medicine ball throw. Specific explosive strength was evaluated by making 3 types of overarm throw: standing position, using an adapted chair (without run-up, T w , a 3-step running throw (T 3-Steps and a jump shot (J S . The jump test (SJ, CMJ and FCMJ were determined using the OptoJump. The medicine ball explosive power test was closely related to T 3-Steps . Significant relationships were observed between medicine ball explosive power tests and (J S and (T w . The Medicine ball explosive power test is also positively related to vertical jump ability represented by Squat Jump (SJ and Countermovement Jump (CMJ. The results suggest an association of the medicine ball explosive power tests to performance in throwing events

  18. The information for catching fly balls : Judging and intercepting virtual balls in a CAVE

    NARCIS (Netherlands)

    Zaal, FTJM; Michaels, CF

    Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy-keeping constant the rate of change of the tangent of the elevation angle (d(tan(alpha))/dt)-leads a catcher to the right location at

  19. The information for catching fly balls: judging and intercepting virtual balls in a CAVE

    NARCIS (Netherlands)

    Zaal, F.T.J.M.; Michaels, C.F.

    2003-01-01

    Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy - keeping constant the rate of change of the tangent of the elevation angle (d(tan(α))/dt) - leads a catcher to the right location at

  20. 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.

  1. Two Cases of Hair Balls in Girls

    Directory of Open Access Journals (Sweden)

    Vladimir A. Shcherbak

    2016-01-01

    Full Text Available This article describes two cases of hair balls in girls between aged 2.5 and 12 years. The reason for this quite rare disease may be trichotillomania (compulsive desire to pull out own hair and trichophagia (compulsive or impulsive desire to pull out, and then to swallow own or someone's hair typical for Rapunzel syndrome. Initially, the children were enrolled in the Oncology Centre in view of suspected abdominal tumour. After detection of foreign bodies in the stomach, they were transferred to the Department of Clean Surgery. The following surgeries were performed: median laparotomy, gastrotomy on the front wall of the stomach, bezoar removal. Hair balls were dense felt-like conglomerates with a strong offensive odour. Bezoar dimensions of the younger girl were 855, the elder one — 20108 cm. Postoperative period was uneventful. The children were discharged in a satisfactory condition to be followed up by a surgeon, paediatrician, and psychiatrist in their community.

  2. James Moores Ball: Ophthalmologist, medical historian, bibliophile.

    Science.gov (United States)

    Feibel, Robert M

    2016-08-01

    James Moores Ball (1862-1929) was an ophthalmologist in St. Louis, Missouri, who excelled as a medical historian and collector of rare and historic books about the history of anatomy. During his lifetime, he was best known as the author of a comprehensive, authoritative, and popular textbook titled Modern Ophthalmology First published in 1904, there were five further editions. Ball was very interested in the history of anatomy and wrote two books on this subject, the first being a biography of Andreas Vesalius, one of the earliest in English, and the second a history of the resurrection men or grave robbers who sold corpses to professors of anatomy and surgery for teaching purposes. His legacy today is the 470 volumes of his personal library, which are now in the Archives and Rare Books department of the Becker Medical Library of the Washington University School of Medicine. These texts are one of their major collections, concentrating on the history of anatomy, beginning with a first edition of Vesalius's De Humani Corporis Fabrica and holding many important and beautiful landmark volumes of anatomical atlases. © The Author(s) 2016.

  3. Accuracy and Reliability of a New Tennis Ball Machine.

    Science.gov (United States)

    Brechbuhl, Cyril; Millet, Grégoire; Schmitt, Laurent

    2016-06-01

    The aim was to evaluate the reliability of a newly-developed ball machine named 'Hightof', on the field and to assess its accuracy. The experiment was conducted in the collaboration of the 'Hawk-Eye' technology. The accuracy and reliability of this ball machine were assessed during an incremental test, with 1 min of exercise and 30 sec of recovery, where the frequency of the balls increased from 10 to 30 balls·min(-1). The initial frequency was 10 and increased by 2 until 22, then by 1 until 30 balls·min(-1). The reference points for the impact were 8.39m from the net and 2.70m from lateral line for the right side and 2.83m for the left side. The precision of the machine was similar on the right and left sides (0.63 ± 0.39 vs 0.63 ± 0.34 m). The distances to the reference point were 0.52 ± 0.42, 0.26 ± 0.19, 0.52 ± 0.37, 0.28 ± 0.19 m for the Y-right, X-right, Y-left and X-left impacts. The precision was constant and did not increase with the intensity. (e.g ball frequency). The ball velocity was 86.3 ± 1.5 and 86.5 ± 1.3 km·h(-1) for the right and the left side, respectively. The coefficient of variation for the velocity ranged between 1 and 2% in all stages (ball velocity ranging from 10 to 30 balls·min(-1)). both the accuracy and the reliability of this new ball machine appear satisfying enough for field testing and training. Key pointsThe reliability and accuracy of a new ball machine named 'Hightof' were assessed.The impact point was reproducible and similar on the right and left sides (±0.63 m).The precision was constant and did not increase with the intensity (e.g ball frequency).The coefficient of variation of the ball velocity ranged between 1 and 2% in all stages (ball velocity ranging from 10 to 30 balls·min(-1)).

  4. Emission Spectroscopy of Atmospheric-Pressure Ball Plasmoids: Higher Energy Reveals a Rich Chemistry

    Science.gov (United States)

    Dubowsky, Scott E.; Rose, Amber Nicole; Glumac, Nick; McCall, Benjamin J.

    2017-06-01

    Ball plasmoids (self-sustaining spherical plasmas) are a particularly unique example of a non-equilibrium air plasma. These plasmoids have lifetimes on the order of hundreds of milliseconds without an external power source, however, current models dictate that a ball plasmoid should recombine in a millisecond or less. Ball plasmoids are considered to be a laboratory analogue of natural ball lightning, a phenomenon that has eluded scientific explanation for centuries. We are searching for the underlying physicochemical mechanism(s) by which ball plasmoids and (by extension) ball lightning are stabilized using a variety of diagnostic techniques. This presentation will focus on optical emission spectroscopy (OES) of ball plasmoid discharges between 190-850 nm. The previous generation of OES measurements of this system showed emission from only a few atomic and molecular species, however, the energy available for the discharges in these experiments was limited by the size of the capacitor banks and voltages to which the capacitor banks were charged. We are capable of generating plasmoids at much higher energies, and as a result we are the first to report a very rich chemistry previously not observed in ball plasmoids. We have identified signals from species including NO A^{2}Σ^{+}→X^{2}Π, OH A^{2}Σ^{+}→X^{2}Π, NH A^{3}Π→X^{3}Σ^{-}, AlO A^{2}Π→X^{2}Σ^{+}, NH^{+} B^{2}Δ→X^{2}Π, W I, Al I, Cu I, and H_{α}, all of which have not yet been reported for this system. Analysis of the emission spectra and fitting procedures will be discussed, rotational temperatures of constituent species will be reported, and theories of ball plasmoid stabilization based upon these new results will be presented. Versteegh, A.; Behringer, K.; Fantz, U.; Fussman, G.; Jüttner, B.; Noack, S. Plas. Sour. Sci. Technol. 2008, 17(2), 024014 Stephan, K. D.; Dumas, S.; Komala-Noor, L.; McMinn, J. Plas. Sour. Sci. Technol. 2013, 22(2), 025018

  5. 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.

  6. How Magnus Bends the Flying Ball - Experimenting and Modeling

    Science.gov (United States)

    Timková, V.; Ješková, Z.

    2017-02-01

    Students are well aware of the effect of the deflection of sports balls when they have been given a spin. A volleyball, tennis, or table tennis ball served with topspin results in an additional downward force that makes the ball difficult to catch and return. In soccer, the effect of sidespin causes the ball to curve unexpectedly sideways, resulting in a so-called banana kick that can confuse the goalkeeper. These surprising effects attract students' attention such that the motion of sports balls can be used to capture the interest of students towards the physics behind it. However, to study and analyze the motion of a real ball kicked in a playfield is not an easy task. Instead of the large-scale full-size sports ball motion, there can be designed and studied simpler experiments that can be carried out in the classroom. Moreover, digital technologies that are available at schools enable students to collect data from the experiment easily in a reasonable time. The mathematical model based on the analysis of forces acting on the ball flying in the air can be used to simulate the motion in order to understand the basic physical principles of the motion so that the best correspondence may be found.

  7. 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

  8. Physical Activity Benefits Creativity: Squeezing a Ball for Enhancing Creativity

    Science.gov (United States)

    Kim, JongHan

    2015-01-01

    Studies in embodied cognition show that physical sensations, such as touch and movement, influence cognitive processes. Two studies were conducted to test whether squeezing a soft versus a hard ball facilitates different types of creativity. Squeezing a malleable ball would increase divergent creativity by catalyzing multiple or alternative ideas,…

  9. Motion of a Ball on a Moving Surface

    Science.gov (United States)

    Cross, Rod

    2016-01-01

    A well-known physics demonstration is to pull a tablecloth rapidly from under some crockery without disturbing the crockery. An interesting question is whether the same result can be expected if the crockery is replaced by a ball, given that the ball might roll backwards on the tablecloth. Theoretical and experimental results are presented showing…

  10. Production of nano structured silicon carbide by high energy ball ...

    African Journals Online (AJOL)

    In this paper, an attempt has been made to modify the micro sized Silicon carbide powder into nano structured Silicon carbide powder using High Energy Ball Mill. Ball milling was carried out for the total duration of 50 hours. The sample was taken out after every 5 hours of milling and it was characterized for its crystallite ...

  11. Why Low Bounce Balls Exhibit High Rolling Resistance

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A simple experiment is described to measure the coefficient of rolling friction for a low bounce ball rolling on a horizontal surface. As observed previously by others, the coefficient increased with rolling speed. The energy loss due to rolling friction can be explained in terms of the measured coefficient of restitution for the ball, meaning…

  12. Between Traditions: Stephen Ball and the Critical Sociology of Education

    Science.gov (United States)

    Apple, Michael W.

    2013-01-01

    Stephen Ball's work has deservedly received a good deal of attention. In this article, I detail a number of tasks in which the critical sociologist of education--as a "public intellectual"--should engage. I then place Ball's work within these tasks and evaluate his contributions to them. In the process, I show that one of the…

  13. 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,…

  14. Exact solutions, energy, and charge of stable Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Marques, M.A. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

    2016-05-15

    In this work we deal with nontopological solutions of the Q-ball type in two spacetime dimensions. We study models of current interest, described by a Higgs-like and other, similar potentials which unveil the presence of exact solutions. We use the analytic results to investigate how to control the energy and charge to make the Q-balls stable. (orig.)

  15. 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

  16. 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.

  17. Two balls and a string: from ordered motion to chaos

    Science.gov (United States)

    Sacks, William; Mauger, Alain

    2013-11-01

    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.

  18. 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.

  19. Une balle blanche dans un roman noir

    Directory of Open Access Journals (Sweden)

    Sophie Vallas

    2012-03-01

    Full Text Available En 1982, Paul Auster fit paraître, sous le pseudonyme de Paul Benjamin, un roman noir intitulé Squeeze Play. Ce roman présente la particularité d’appartenir également au genre du baseball novel, l’intrigue se déroulant en partie dans le monde du base-ball et sa résolution intervenant grâce à une manœuvre rare et spectaculaire (un double suicide squeeze qui éclaire l’enquête sous un jour nouveau. Cet article se propose d’analyser la place du base-ball dans Squeeze Play : élément essentiel de la structuration du roman, le base-ball permet également à Auster d’étudier le mythe du héros américain déchu dans une société dont toutes les dimensions (sportive, politique, privée sont gangrenées par la corruption et la perversion. La relation particulière qu’Auster tisse entre roman noir et baseball novel est également étudiée.In 1982 Paul Auster published a roman noir entitled Squeeze Play under the pseudonym of Paul Benjamin. The novel is also a “baseball novel”: its plot essentially deals with a baseball New York team and its former, fallen star, and the final resolution of the mystery intervenes thanks to a revelation brought by a baseball game in which a rather rare and spectacular maneuver (the double suicide squeeze is used by one of the teams to turn the tables and win the game. This paper analyzes the place of baseball in Squeeze Play: it first appears as an essential element in the very structure of the plot, but it is also, for Auster, a way of questioning the myth of the hero in an American society whose main aspects (sports, politics, private life are eaten up by corruption and perversion. The links Auster establishes between roman noir and baseball novel are also dealt with.

  20. 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.

  1. ANALYSES OF VOLLEY-BALL TECHNIQUE OF BALL SHOTING AT ALOFT BOUNCE BY USING KINEMATICS METHOD

    Directory of Open Access Journals (Sweden)

    Radoslav Bubanj

    2008-08-01

    Full Text Available In the sports hall, student of Faculty of sports and physical education demonstrated technique of ball shoting at aloft bounce in volley-ball. That element of technique was recorded by using of digital camera. Video record was mistreated and prepared for further manipulating which considered admeasurement of reference points on 13-th model system withdrawal of appropriate ”Human“ software. After that, basics kinematics variables were calculated. All results were graphically presented and interpreted. Descriptive method was used as supplementary method which gave informations about impacts of single handed velocities of body segments on length of horizontally and vertically path which outpassed body gravity centre. Descriptive method also gave results about regularity of performed complex element of technique.

  2. Poincare ball embeddings of the optical geometry

    International Nuclear Information System (INIS)

    Abramowicz, M A; Bengtsson, I; Karas, V; Rosquist, K

    2002-01-01

    It is shown that the optical geometry of the Reissner-Nordstroem exterior metric can be embedded in a hyperbolic space all the way down to its outer horizon. The adopted embedding procedure removes a breakdown of flat-space embeddings which occurs outside the horizon, at and below the Buchdahl-Bondi limit (R/M=9/4 in the Schwarzschild case). In particular, the horizon can be captured in the optical geometry embedding diagram. Moreover, by using the compact Poincare ball representation of the hyperbolic space, the embedding diagram can cover the whole extent of radius from spatial infinity down to the horizon. Attention is drawn to the advantages of such embeddings in an appropriately curved space: this approach gives compact embeddings and it clearly distinguishes the case of an extremal black hole from a non-extremal one in terms of the topology of the embedded horizon

  3. Unpredictable Property of a Kicked Billiard Ball

    International Nuclear Information System (INIS)

    Shen Ying; Dai Jun; Jiang Yumei; He Yue; He Daren

    2006-01-01

    A simultaneous change in the systemic property of a kicked billiard ball is observed from an entirely smooth and conservative state to a piecewise smooth and quasi-dissipative state when a single controlling parameter has been adjusted. The transition induces a sudden change of a typical conservative stochastic web into a transient web. The iterations on the transient web eventually escape to some elliptic islands. In the meantime, a fat fractal forbidden web, which appears also at the threshold, grows up and cuts away increasingly more parts from the original conservative stochastic web. We numerically show that the initial conditions that generated different attractors are mixed in a random manner and the pattern remains unchanged even when smaller and smaller scales are used for examination, indicating a riddle-like basin structure that practically rules out the possibility of predicting the attractors from a given initial condition

  4. Theory of the Motion of Ball Lightning

    Science.gov (United States)

    Handel, Peter

    2008-04-01

    The Maser-Soliton Theory of BL predicts the dynamics of each of the harmonic waves in the wave packet that feeds and in fact defines the Langmuir plasma soliton that is observed as BL. The frequencies in the wave packet are in a narrow window f that corresponds in the case of open air BL to the diameter of the area in which the damage caused by the final explosion of the BL is observed. This is usually of the order of δx=30 m roughly, in rms. The corresponding wave vector interval is δk=(1/2)(1/30m)=0.017/m in rms. At the same time, k is of the order of 6/m, yielding k/δk=360. This pronounced line-narrowing is obtained due to the large gain of the atmospheric maser when it generates the Kapitsa standing wave. Phase differences between the waves that make up the electromagnetic field that couples with the electrostatic field of the soliton are determined by the frequency dependence of gain and dissipation. They are influenced less by the motion of the air, than by the maser dynamics and by the boundary conditions shaping the electromagnetic field, i.e. the individual photonic wave-packet. The paper presents the equations that determine the phase dynamics and therefore also the observed motion of BL. A similar phase dynamics is expected to be applicable to the special case of UFO motions.

  5. 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

  6. Do we hear size or sound? Balls dropped on plates.

    Science.gov (United States)

    Grassi, Massimo

    2005-02-01

    The aim of this study is to examine whether it is possible to recover directly the size of an object from the sound of an impact. Specifically, the study is designed to investigate whether listeners can tell the size of a ball from the sound when it is dropped on plates of different diameters (on one, two, or three plates in Experiments 1, 2, and 3, respectively). In this paradigm, most of the sound produced is from the plate rather than the ball. Listeners were told neither how many different balls or plates were used nor the materials of the balls and plates. Although listeners provided reasonable ball size estimates, their judgments were influenced by the size of the plate: Balls were judged to be larger when dropped on larger plates. Moreover, listeners were generally unable to recognize either ball and plate materials or the number of plates used in Experiments 2 and 3. Finally, various acoustic properties of the sounds are shown to be correlated with listeners' judgments.

  7. THEORETICAL ANALYSIS OF THE FORGING PROCESS FOR PRODUCING HOLLOW BALLS

    Directory of Open Access Journals (Sweden)

    Grzegorz Winiarski

    2013-06-01

    Full Text Available Hollow balls are used in the production of various machines and devices. The technology for producing hollow balls by metal forming technologies poses numerous difficulties connected with the forming of a hollow billet. The billet, which is usually in a form of a rod, is a subject to such processes as forging, helical rolling or cross-wedge rolling. The paper discusses a new method and conditions for producing a hollow ball. It was assumed that the ball would be produced in two forging operations: an initial forging operation and finishing forging operation. The presented results are based on the FEM numerical analysis conducted using DEFORM-3D. It was assumed that the billet material was made of AISI 304 stainless steel used to produce balls for ball valves. Both the shape progression during the forging process and variations in the forming force were analyzed. Based on the conducted analyses, it can be claimed that hollow balls can be produced using the proposed forging method.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Defects Detection on Silicon Nitride Balls by Laser Ultrasonics

    International Nuclear Information System (INIS)

    Lemaire, M.; Ouaftouh, M.; Duquennoy, M.; Jenot, F.; Ourak, M.

    2005-01-01

    In this work, we study the generation and the detection of surface waves on silicon nitride balls a few millimetres in diameter. The excitation of these waves is carried out thanks to a pulsed laser YAG and their detection is achieved with a laser interferometric probe. The whole of the device requires neither coupling nor direct contact with the balls. These waves are then used for the analysis of defects close to the surface of the balls. Several measurements are carried out on samples presenting various defects. Correlation attempts are also carried out between some ultrasonic parameters and some characteristics of defects

  13. Einleitung der Bibliografie "Fußball als Kulturgut"

    OpenAIRE

    Schiffer, Jürgen

    2006-01-01

    "Die Auffassung, dass 'Fußball auch ein Stück Kultur' sei (Beckenbauer zit. von Adelmann et al. 2003), ist alles andere als eine Selbstverständlichkeit. Lange Zeit wurde das Fußballspiel als geistloser 'Proletensport' geschmäht (Herzog 2002). Insbesondere in seinen Anfangszeiten, Ende des 19. Jahrhunderts, sah sich der in Deutschland aufkommende Fußball zahlreichen Attacken ausgesetzt. So beschrieb Karl Planck (1898, repr. 1982) den Fußball in seiner polemischen Schrift, die gegen dieses von ...

  14. 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.

  15. 78 FR 29702 - Ball Bearings and Parts Thereof From Germany: Final Results of Antidumping Duty Administrative...

    Science.gov (United States)

    2013-05-21

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-428-801] Ball Bearings and Parts... administrative review of the antidumping duty order on ball bearings and parts thereof from Germany. The period... ball bearings and parts thereof from Germany as the conclusion of a sunset review. See Ball Bearings...

  16. 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

  17. Effects of Varying Ball Bearing Cleaning Processes on Lubricant Life

    National Research Council Canada - National Science Library

    Didziulis, S

    1998-01-01

    The processes used to clean ball bearings and other components in precision spacecraft mechanisms have undergone significant changes to eliminate the use of ozone depleting chemicals, such as Freon TF...

  18. Pink Cricket Balls May Be Visually Challenging at Sunset

    Directory of Open Access Journals (Sweden)

    Joshua M. Adie

    2017-02-01

    Full Text Available Cricket is one of the world’s most popular sports, followed by hundreds of millions of people. It can be dangerous, played with a hard ball flying at great velocities, and accidents have occasionally been fatal. Traditionally, cricket has been played during the day, using a dark red ball. Since the late 1970s, a shorter form of one-day cricket has been played both during the day and at night under floodlights. To overcome visibility issues, one-day cricket uses a white ball, and players wear coloured clothing. There is now a desire to play a traditional form of cricket during the day and at night, using a ‘pink’ ball while players wear white clothing. Concerns regarding visibility, and player and umpire safety, have been raised in this context. Here, we report that these concerns have a sound basis.

  19. Mechanisms of dry ball milling in MOX fabrication

    International Nuclear Information System (INIS)

    Warin, D.; Bauer, M.; Seiss, M.; Lorenzelli, R.

    1997-01-01

    An important stage of MOX fuel pellets fabrication is the blending process of the nuclear powders which is carried out in the French plants in a ball milling and under dry conditions in order to avoid any criticality related difficulties. The milled powders must present a sufficiently intimate distribution of the UO 2 and PuO 2 particles which is necessary to synthesize the homogeneous (UPu)O 2 solid solution during the subsequent reactive sintering; the homogeneity of the UP 2 /PuO 2 fuels is important in relation both to uniform irradiation performance and to solubility during reprocessing. This study is related to the mechanisms which take place inside the ball mill as a function of the nature and size of the balls, the rotation speed, the milling time and the mill-to-ball charge-to-powder volume ratios. 4 refs, 3 figs

  20. 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....

  1. 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.

  2. Confirming a case of ball lightening production

    Energy Technology Data Exchange (ETDEWEB)

    Balyberdin, V.V.

    1975-01-01

    Model confirmation of ball lightening production was carried out on a three-cascade unit having a working voltage of 150 kV in an air atmosphere at a pressure of 730 to 750 mg Hg std. with C-shaped bending of the lightening drawoff. The electrical discharge parameters were held constant as follows: maximum current amplitude of 7 kA, oscillatory period of the quenched discharge of 6.5 x 10/sup -6/ sec, and energy used up in the unit approximately 2.2 k joules. Moving pictures are presented of the generation of one long luminous bundle displaced from a solid with a velocity up to 240 m/sec, whose luminosity was observed over a period of approximately 3 x 10/sup -3/ sec. Analysis of the experimental results showed that the appearance of plasma bundles is associated with the development of turbulent flows of a low-temperature plasma near the tip of a solid. (SJR)

  3. Nano-porous calcium phosphate balls.

    Science.gov (United States)

    Kovach, Ildyko; Kosmella, Sabine; Prietzel, Claudia; Bagdahn, Christian; Koetz, Joachim

    2015-08-01

    By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Data interpolation using rational cubic Ball spline with three parameters

    Science.gov (United States)

    Karim, Samsul Ariffin Abdul

    2016-11-01

    Data interpolation is an important task for scientific visualization. This research introduces new rational cubic Ball spline scheme with three parameters. The rational cubic Ball will be used for data interpolation with or without true derivative values. Error estimation show that the proposed scheme works well and is a very good interpolant to approximate the function. All graphical examples are presented by using Mathematica software.

  5. A dynamic styrofoam-ball model for simulating molecular motion

    Science.gov (United States)

    Mak, Se-yuen; Cheung, Derek

    2001-01-01

    In this paper we introduce a simple styrofoam-ball model that can be used for simulating molecular motion in all three states. As the foam balls are driven by a vibrator that is in turn driven by a signal generator, the frequency and the amplitude of vibration can be adjusted independently. Thus, the model is appropriate for simulating molecular motion in the liquid state, which is a combination of vibration and meandering motion.

  6. Attempted - to -Phase Conversion of Croconic Acid via Ball Milling

    Science.gov (United States)

    2017-05-18

    CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 16 19a. NAME OF RESPONSIBLE PERSON Steven W...stainless steel ball and vessel. ................ 6 Fig. 6 Representative heat flow traces for milled CA samples. Curves have been offset to enhance...stainless steel . The ball has a diameter of 6.35 mm and a mass of 1 g; the vessel outer diameter is 12.7 mm, and the vessel length is 27.7 mm. A series

  7. Linearly convergent stochastic heavy ball method for minimizing generalization error

    KAUST Repository

    Loizou, Nicolas

    2017-10-30

    In this work we establish the first linear convergence result for the stochastic heavy ball method. The method performs SGD steps with a fixed stepsize, amended by a heavy ball momentum term. In the analysis, we focus on minimizing the expected loss and not on finite-sum minimization, which is typically a much harder problem. While in the analysis we constrain ourselves to quadratic loss, the overall objective is not necessarily strongly convex.

  8. Brown carbon in tar balls from smoldering biomass combustion

    OpenAIRE

    R. K. Chakrabarty; H. Moosmüller; L.-W. A. Chen; K. Lewis; W. P. Arnott; C. Mazzolen; M. Dubey; C. E. Wold; W. M. Hao; S. M. Kreidenweis

    2010-01-01

    We report the direct observation of laboratory production of spherical, carbonaceous particles – "tar balls" – from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Ångström coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent imaginary part of its refractive index – optically defined as "brown carbon" – is an important component of tar balls. The spectrum of the...

  9. Atmospheric tar balls: aged primary droplets from biomass burning?

    OpenAIRE

    Tóth, A.; Hoffer, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2014-01-01

    Atmospheric tar balls are particles of special morphology and composition that are fairly abundant in the plumes of biomass smoke. These particles form a specific subset of brown carbon (BrC) which has been shown to play a significant role in atmospheric shortwave absorption and, by extension, climate forcing. Here we suggest that tar balls are produced by the direct emission of liquid tar droplets followed by heat transformation upon biomass burning. For the first time in a...

  10. Effect of Hoop Stress on Ball Bearing Life Prediction

    Science.gov (United States)

    Zaretsky, Erwin V.; August, Richard; Coe, Harold H.

    1995-01-01

    A finite-element analysis (FEA) of a generic, dimensionally normalized inner race of an angular-contact ball bearing was performed under varying conditions of speed and the press (or interference) fit of the inner-race bore on a journal. The FEA results at the ball-race contact were used to derive an equation from which was obtained the radius of an equivalent cylindrical bearing race with the same or similar hoop stress. The radius of the equivalent cylinder was used to obtain a generalized closed-form approximation of the hoop stresses at the ball-inner-race contact in an angular-contact ball bearing. A life analysis was performed on both a 45- and a 120-mm-bore, angular-contact ball bearing. The predicted lives with and without hoop stress were compared with experimental endurance results obtained at 12000 and 25000 rpm with the 120-mm-bore ball bearing. A life factor equation based on hoop stress is presented.

  11. Automatic optical inspection system design for golf ball

    Science.gov (United States)

    Wu, Hsien-Huang; Su, Jyun-Wei; Chen, Chih-Lin

    2016-09-01

    ith the growing popularity of golf sport all over the world, the quantities of relevant products are increasing year by year. To create innovation and improvement in quality while reducing production cost, automation of manufacturing become a necessary and important issue. This paper reflect the trend of this production automa- tion. It uses the AOI (Automated Optical Inspection) technology to develop a system which can automatically detect defects on the golf ball. The current manual quality-inspection is not only error-prone but also very man- power demanding. Taking into consideration the competition of this industry in the near future, the development of related AOI equipment must be conducted as soon as possible. Due to the strong reflective property of the ball surface, as well as its surface dimples and subtle flaws, it is very difficult to take good quality image for automatic inspection. Based on the surface properties and shape of the ball, lighting has been properly design for image-taking environment and structure. Area-scan cameras have been used to acquire images with good contrast between defects and background to assure the achievement of the goal of automatic defect detection on the golf ball. The result obtained is that more than 973 of the NG balls have be detected, and system maintains less than 103 false alarm rate. The balls which are determined by the system to be NG will be inspected by human eye again. Therefore, the manpower spent in the inspection has been reduced by 903.

  12. Atmospheric tar balls: Particles from biomass and biofuel burning

    Science.gov (United States)

    Pósfai, MiháLy; GelencséR, AndráS.; Simonics, RenáTa; Arató, Krisztina; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2004-03-01

    "Tar balls" are amorphous, carbonaceous spherules that occur in the tropospheric aerosol as a result of biomass and biofuel burning. They form a distinct group of particles with diameters typically between 30 and 500 nm and readily identifiable with electron microscopy. Their lack of a turbostratic microstructure distinguishes them from soot, and their morphology and composition (˜90 mol % carbon) renders them distinct from other carbonaceous particles. Tar balls are particularly abundant in slightly aged (minutes to hours old) biomass smoke, indicating that they likely form by gas-to-particle conversion within smoke plumes. The material of tar balls is initially hygroscopic; however, the particles become largely insoluble as a result of free radical polymerization of their organic molecules. Consequently, tar balls are primarily externally mixed with other particle types, and they do not appreciably increase in size during aging. When tar balls coagulate with water-bearing particles, their material may partly dissolve and no longer be recognizable as distinct particles. Tar balls may contain organic compounds that absorb sunlight. They are an important, previously unrecognized type of carbonaceous (organic) atmospheric particle.

  13. Theory of operation for the ball rheometer

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, C.L.; Colson, J.B. [Pacific Northwest Lab., Richland, WA (United States); Pasamehmetoglu, K.O.; Unal, C.; Edwards, J.N.; Abbott, J. [Los Alamos National Lab., NM (United States)

    1994-12-01

    The Hanford Site contains over 100 high-volume tanks containing high-level radioactive wastes. The tank which has received the most attention is Tank 101-SY, which is a double shell tank containing a caustic mixed-waste slurry. The ball rheometer developed in this work is intended at least initially for application in this tank. Tank 101-SY is known to periodically release flammable and toxic gases during events known as rollovers. The tank waste is largely made up of two layers, a supernatant liquid layer underneath which is a thick sludge layer. The two layers are called the convective (C) and the nonconvective (NC) regions, so called because of the thermal transport properties ascribed to each. Although they have significant uncertainty, the current theology data suggest the existence of a yield stress in the highly viscous nonconvective layer. Gas generated in the waste can be held in the NC layer if the material yield strength or its viscosity is high enough. Gas cannot be held in the C layer to any appreciable extent unless it is in solution. As gas continues to be generated by chemical or other processes, the number of gas bubbles and/or their sizes increases in the NC layer. A rollover occurs when the amount of gas trapped in the nonconvective region becomes great enough to overcome forces holding it in place. These forces are believed to be dependent on the theology of the nonconvective region and perhaps the bubble surface tension. The buoyancy forces on the bubbles exceed the restraining forces arising from the yield stress and the viscosity of the NC layer. Theology is then seen to be quite important in determining the nature of gas release events in this tank.

  14. Quenching simulation of steel grinding balls

    Directory of Open Access Journals (Sweden)

    Zapata-Hernández, Oscar

    2015-09-01

    Full Text Available The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.Las transformaciones de fase en aceros de alto carbono durante su temple y un posterior periodo de estabilización fueron modelizadas por medio del uso de paquetes computacionales basados en el método del elemento finito y de la transformación cinética de los aceros. El modelo se usó para predecir los cambios de temperatura y microestructura que se presentan en bolas de dos diferentes tamaños empleadas en estaciones de molienda de minerales. Se encontró una buena correlación entre las temperaturas medidas mediante la inserción de termopares y aquellas predichas por el modelo una vez que se modificó la conductividad térmica del acero en el intervalo mixto de fases. La predicción de las transformaciones de fase se confirmó a través del análisis metalográfico.

  15. 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.

  16. Grounding, Bonding, Shielding, and Lightning Bibliography 1972 to 1979

    Science.gov (United States)

    1981-02-01

    channel. The interaction of lightning and aircraft is included. A discussion of ball lightning is included. H. H. Hoshiko, "Helical Channel Multiplier...project Telsa which produced artificial ball lightning with potentials as large as 20 million volts and provides a brief explanation of the hazards of... ball lightning . S. Stoller, "In-Plant Generation-Design Considerations for Industrial Facilities," IEEE Transactions on Industry Applications, vol. IA-12

  17. 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.

  18. 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.

  19. Reliability of a New Medicine Ball Throw Power Test.

    Science.gov (United States)

    Sayers, Mark G L; Bishop, Stephen

    2017-08-01

    The purpose of this study was to examine the reliability of a new upper body medicine ball push-press (MBP-P) test. Twenty-three strength trained volunteers performed a series of supine MBP-P throws using loads representing 5% and10% of their 5RM bench press (5 repetitions at each load). Throws were performed on a force platform (2000 Hz), with medicine ball kinematic data collected using a high-speed motion capture (500 Hz). Testing was repeated after 7-10 days to quantify intertest reliability. Maximal force (F max ), impulse at F max , time to F max , and maximum rate of force development (RFD max ) were all calculated from the force platform outputs, with maximum ball velocity (Vel max ) and maximum ball acceleration (Accel max ) developed from the kinematic data. Reliability was assessed using intraclass correlation (ICC), coefficient of variation (%CV), and typical error. Medicine ball kinematic variables were more reliable (CV% = 2.6-5.3, ICC = 0.87-0.95) than the various force platform derived power variables (CV% = 7.9-26.7, ICC = 0.51-0.90). The MBP-P test produces reliable data and can be used to quantify many standard power based measures, with the key findings have implications for athletic populations requiring high velocity, light load upper body pushing power.

  20. New data on the formation of Carboniferous coal balls

    Energy Technology Data Exchange (ETDEWEB)

    Scott, A.C.; Mattey, D.P.; Howard, R. [University of London, Egham (United Kingdom). Royal Holloway and Bedford New College, Dept. of Geology

    1996-10-01

    Coal balls are formed from the precipitation of carbonate minerals, predominantly calcite, from water during or immediately post-peat formation. Previous petrological studies suggest permineralization occurred at various stages during the peatificiation process by precipitation from a mixture of marine and meteoric freshwater. The geochemical studies reported here aimed to test previous theories of coal ball formation. The coal balls studied are from Upper Carboniferous and Carboniferous/Permian coal seams in Britain, United States of America, Belgium and China. Stable carbon isotopic values of calcites range from {delta}{sup 13}C of -5 to -35 parts per thousand indicating highly variable contribution of decayed organic matter to the carbonate cement. Oxygen isotopic values of delta({sup 18}) range from -3 to -15 parts per thousand suggest both marine and meteoric freshwater sources. The range, in the British coal balls in particular, with {delta}{sup 13}C ranging from -7 to -25 parts per thousand indicates the complexity of carbonate generation. Isotopic data support at least four theories of carbonate coal ball formation. This makes their absence from post-Permian coals the more puzzling and it is suggested that the overall structure of the peat may play a role.

  1. 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

  2. Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-07-01

    Full Text Available Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization of heavy metals in municipal solid waste incineration (MSWI fly ash. Three heavy metals (Cu, Cr, Pb loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

  3. Atmospheric tar balls: aged primary droplets from biomass burning?

    Science.gov (United States)

    Tóth, A.; Hoffer, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2014-07-01

    Atmospheric tar balls are particles of special morphology and composition that are fairly abundant in the plumes of biomass smoke. These particles form a specific subset of brown carbon (BrC) which has been shown to play a significant role in atmospheric shortwave absorption and, by extension, climate forcing. Here we suggest that tar balls are produced by the direct emission of liquid tar droplets followed by heat transformation upon biomass burning. For the first time in atmospheric chemistry we generated tar-ball particles from liquid tar obtained previously by dry distillation of wood in an all-glass apparatus in the laboratory with the total exclusion of flame processes. The particles were perfectly spherical with a mean optical diameter of 300 nm, refractory, externally mixed, and homogeneous in the contrast of the transmission electron microscopy (TEM) images. They lacked any graphene-like microstructure and exhibited a mean carbon-to-oxygen ratio of 10. All of the observed characteristics of laboratory-generated particles were very similar to those reported for atmospheric tar-ball particles in the literature, strongly supporting our hypothesis regarding the formation mechanism of atmospheric tar-ball particles.

  4. Rotating and rolling rigid bodies and the "hairy ball" theorem

    Science.gov (United States)

    Bormashenko, Edward; Kazachkov, Alexander

    2017-06-01

    Rotating and rolling rigid bodies exemplify a fascinating theorem of topology, jokingly called the "hairy ball" theorem, which demands that any continuous tangent vector field on the sphere has at least one point where the field is zero. We demonstrate via a gedanken experiment how drilling through a rotating ball, thereby converting it into a torus, leads to the elimination of zero-velocity points on the ball surface. Using the same reasoning, zero-velocity points can be removed from the surface of a drilled spinning top. We discuss the location of zero-velocity points on the surfaces of rigid bodies rolling with no slip and with slip. Observations made from different reference frames identify various zero-velocity points. Illustrative experiments visualizing zero-velocity points are presented.

  5. Durability Tests of Ball Valve Prototype with Flowmeter Operation

    Science.gov (United States)

    Rogula, J.; Romanik, G.

    2018-02-01

    The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

  6. 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.

  7. 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

  8. A Case of Lung Lesions Induced by a soccer Ball

    Directory of Open Access Journals (Sweden)

    Masaaki Takemoto

    2013-01-01

    Full Text Available An 18-year-old youth soccer forward received a direct hit from a kicked soccer ball on the anterior right chest when the goal keeper kicked the ball from a distance of 1 meter. Immediately following the hit, the subject experienced dypnea, chest pain and had a cough, with several milliliters of hemoptysis. His symptoms subsided after 20 minutes of rest. However, he still felt mild discomfort and was taken to our department for evaluation. On examination, all vital signs were normal. A computed tomography scan of the chest was obtained, and revealed a small area of opacification in the right lung field suggesting a pulmonary contusion or traumatic lung edema. Ten days after the initial injury, he was cleared for full participation. We herein reported the first case of a lung lesion induced by a soccer ball. Conservative treatment resulted in a favorable outcome.

  9. 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.

  10. Comparison of exit time moment spectra for extrinsic metric balls

    DEFF Research Database (Denmark)

    Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente

    2012-01-01

    We prove explicit upper and lower bounds for the $L^1$-moment spectra for the Brownian motion exit time from extrinsic metric balls of submanifolds $P^m$ in ambient Riemannian spaces $N^n$. We assume that $P$ and $N$ both have controlled radial curvatures (mean curvature and sectional curvature......, respectively) as viewed from a pole in $N$. The bounds for the exit moment spectra are given in terms of the corresponding spectra for geodesic metric balls in suitably warped product model spaces. The bounds are sharp in the sense that equalities are obtained in characteristic cases. As a corollary we also...... obtain new intrinsic comparison results for the exit time spectra for metric balls in the ambient manifolds $N^n$ themselves....

  11. 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.

  12. Note: A 1-m Foucault pendulum rolling on a ball

    Science.gov (United States)

    Salva, H. R.; Benavides, R. E.; Venturino, J. A.; Cuscueta, D. J.; Ghilarducci, A. A.

    2013-10-01

    We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.

  13. Field-ball milling induced anisotropy in magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Poudyal, Narayan [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Altuncevahir, Baki [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chakka, Vamsi [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chen Kanghua [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Black, Truman D [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Liu, J Ping [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Ding, Yong [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2004-12-21

    Nd{sub 2}Fe{sub 14}B and Sm{sub 2}Co{sub 17} particles of submicrometre sizes have been prepared by ball milling in a magnetic field. Structural and magnetic characterization reveal that these submicrometre particles milled in a magnetic field, consisting of nanosize grains, exhibit strong magnetic anisotropy compared with the particles milled without a magnetic field. Based on in situ observations of the field-ball milling in a transparent container, the mechanism of field-induced anisotropy in the nanostructured hard magnetic particles is discussed. (rapid communication)

  14. Spin Rate and Deflection Ratio of a Ping Pong Ball

    Directory of Open Access Journals (Sweden)

    Byung Joon Ahn

    2013-12-01

    Full Text Available To investigate the effects of a spherical object’s spin rate on the curvature of its flight, Ping Pong balls, of varying spin rates, were hit horizontally and recorded from above with a high-speed camera. It was shown that there was a proportional relationship between the ball’s spin rate and deflection ratio. Additionally, using the results of the analyzed data, a coefficient of skin friction of the Ping Pong ball was found to be approximately 0.2 under the specific conditions of this investigation.

  15. Spin Rate and Deflection Ratio of a Ping Pong Ball

    Directory of Open Access Journals (Sweden)

    Byung Joon Ahn

    2013-01-01

    Full Text Available To investigate the effects of a spherical object’s spin rate on the curvature of its flight, Ping Pong balls, of varying spin rates, were hit horizontally and recorded from above with a high-speed camera. It was shown that there was a proportional relationship between the ball’s spin rate and deflection ratio. Additionally, using the results of the analyzed data, a coefficient of skin friction of the Ping Pong ball was found to be approximately 0.2 under the specific conditions of this investigation.

  16. Ball Lens Fiber Optic Sensor based Smart Handheld Microsurgical Instrument.

    Science.gov (United States)

    Song, Cheol; Gehlbach, Peter L; Kang, Jin U

    2013-03-20

    During freehand performance of vitreoretinal microsurgery the surgeon must perform precise and stable maneuvers that achieve surgical objectives and avoid surgical risk. Here, we present an improved smart handheld microsurgical tool which is based on a ball lens fiber optic sensor that utilizes common path swept source optical coherence tomography. Improvements include incorporation of a ball lens single mode fiber optic probe that increases the working angle of the tool to greater than 45 degrees; and increases the magnitude of the distance sensing signal through water. Also presented is a cutting function with an improved ergonomic design.

  17. Image enlargement using biharmonic Said-Ball surface

    Science.gov (United States)

    Saaban, A.; Kherd, A.; Jameel, A. F.; Akhadkulov, H.; Alipiah, F. M.

    2017-09-01

    This paper discusses the use of biharmonic cubic Said-Ball surfaces in image enlargement area. Resizing an image through up sampling or down sampling is generally common for making smaller image fit a bigger screen in full screen mode or reducing a higher resolution image to a smaller resolution. However due to some limitation, this paper will focus on image enlargement based on scaling factor of two. We use biharmonic cubic Said-Ball subject to a given four boundary curves condition respectively. We implement and evaluate the performance of the proposed method based on peak signal to noise ratio (PSNR) indicator using well-known gray-scale test images.

  18. Note: A 1-m Foucault pendulum rolling on a ball.

    Science.gov (United States)

    Salva, H R; Benavides, R E; Venturino, J A; Cuscueta, D J; Ghilarducci, A A

    2013-10-01

    We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.

  19. 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.

  20. Identification of sources of tar balls deposited along the Goa coast, India, using fingerprinting techniques

    Digital Repository Service at National Institute of Oceanography (India)

    Suneel, V.; Vethamony, P.; Zakaria, M.P.; Naik, B.G.; Prasad, K.V.

    Deposition of tar balls along the coast of Goa, India is a common phenomenon during the southwest monsoon. Representative tar ball samples collected from various beaches of Goa and one Bombay High (BH) crude oil sample were subjected to fingerprint...

  1. Noninvasive medical management of fungus ball uropathy in a premature infant.

    Science.gov (United States)

    Alkalay, A L; Srugo, I; Blifeld, C; Komaiko, M S; Pomerance, J J

    1991-09-01

    Unilateral renal obstruction secondary to fungus balls is described in a premature infant. Noninvasive medical management, which included amphotericin B and 5-flucytosine therapy and forced diuresis, resulted in disappearance of fungus balls and resolution of the obstruction.

  2. THE EFFECT OF GAMES AND TRAINING PROGRAMS OFFERED AT BALL SCHOOL (BALSCHULE, ON BALL-COORDINATION AMONG FIRST AND SECOND GRADE STUDENTS

    Directory of Open Access Journals (Sweden)

    Behrooz Ebrahimi

    2013-06-01

    Full Text Available The aim of this study is to investigate the effect of games and training programs offered at the Ball school (Ballschule Heidelberg, on ball-coordination among first and second grade students. For this purpose, 38 students from 13 schools covered by the Ball school (Heidelberg Balschule, were chosen as the experimental group (non-random ; in the meantime the consent of the students’ parents were also received. Forty students as well as a control group (non-random of eight normal schools were selected with parental consents. Then through using ball-coordination tests [BKT (BallKoordinationstests. Ball Coordination’s Tests], the level of the ball skills among both groups were measured in the pre-test and Post-test. Tests included kicking ball against the wall (under five conditions. The research methods were semi-experimental with experimental and control groups. Independent variables were also applied to the experimental group and the means and standard deviations were calculated through descriptive statistics. And then, a T-test for statistical analysis of data in related groups were applied. The results showed a significant effect of games and training programs offered at the school ball in the ball-coordination of subjects.

  3. A jelly model for a ball of an extremely hot plasma

    OpenAIRE

    Kornyushin, Yuri

    2007-01-01

    A simple model is applied to study a high temperature rather dense plasma ball. It is assumed that the ions and delocalized electrons are distributed uniformly throughout the ball, and extra/missing charge is found in a thin layer on the surface of a ball. It is shown in the framework of this model that regarded plasma ball can be relatively stable as a metastable state. Calculations show that electrostatic forces, repulsive forces between the ions, and atmospheric pressure can provide stabil...

  4. Multiple collisions of two steel balls in a Newton’s cradle

    Science.gov (United States)

    Cross, Rod

    2018-03-01

    Multiple collisions of two steel balls in a Newton’s cradle were filmed in order to measure the coefficient of restitution of the balls. Two different initial conditions were examined, one where the balls approached each other at about the same speed, and one where one ball was initially at rest. In theory, the fractional energy loss per collision is different in each case, but the experimental results indicated that the overall energy loss was about the same in both cases.

  5. Consumer Acceptance of Seaweed Ball (Eucheuma Cottonii) Fortified with Catfish Protein Concentrate (Pangasius Hypophthalmus)

    OpenAIRE

    Naibaho, Marianche F; ', Dewita; ', Edison

    2014-01-01

    The study was conducted to evaluate consumer acceptance of seaweed ball fortified with catfish protein concentrate . About 5 kg seaweed was taken from a fish market in Pekanbaru. Three types of seaweed balls were prepared from seaweed flour which was fortificated respectively with 5%, 10%, and 15% catfish protein concentrate. The seaweed balls were evaluated for consumer acceptance and chemical composition. The results indicate that the seaweed balls added with 15% catfish protein concentrate...

  6. Ball milling and annealing of Co-50 at% W Powders

    CSIR Research Space (South Africa)

    Bolokang, AS

    2013-04-01

    Full Text Available annealing of unmilled compacts yielded metastable phases. Upon 10 and 20 h ball milling of Co-W powder, no alloying was obtained. Although milling did not yield significant crystal changes in W and Co ground state struc- tures, its effect is evident during...

  7. Catching fly balls: a simulation study of the Chapman strategy

    NARCIS (Netherlands)

    Kistemaker, D.A.; Faber, H.; Beek, P.J.

    2009-01-01

    Chapman [Chapman, S. (1968). Catching a baseball. American Journal of Physics, 36, 868-870] showed that a catcher may be guided to the landing spot of a fly ball by zeroing out its optical acceleration. Subsequently, various studies have provided evidence for what is now known as the Chapman

  8. Ball game watching theory in the teaching site

    Science.gov (United States)

    Liu, Shugang; Li, Xiufang; Chuang, Chin-Jung

    2017-08-01

    Lecturing is a common approach in the traditional teaching site. In this paper, we bring a modern model "ball game watching theory" to explain the situation in the classroom. The reason why the audiences going to the court is to enjoy the atmosphere, and it is also the reason why student joining to the class. A successful class running is to create studious atmosphere. However, once the teacher does the demo in the class, the multimedia tool must be used to show the details, as the big display working in the court. The key moment is recorded and the details are magnified. when teaching aids are demonstrated, the multimedia tool plays an important role. The attention of students walks between the teacher and the display. In this ball game watching theory, the demonstrate experience is like the ball game, and the teacher works as an anchor. By following the demonstration proceeding, students build the knowledge by themselves. In addition, the demonstration must be designed to be interesting in order to make the class proceed fluently. The similarity between the ball game watching and the class will be discussed. Finally we suggest a modern class design which can raise learner motivation and achievement.

  9. Fuzzy controller for better tennis ball robot | Nguyen | Journal of ...

    African Journals Online (AJOL)

    This paper aims at designing a tennis ball robot as a training facility for tennis players. The robot is built with fuzzy controller which provides proper techniques for the players to gain practical experience as well as technical skills; thus, it can effectively serve the community and train athletes in the high-performance sport.

  10. Preliminary Studies on the Development of Meat Balls | Igene ...

    African Journals Online (AJOL)

    The UUFB sample was rated highest in terms of overall likeness and may economically complement some of the existing popular meat-based snacks in Nigeria. The significance of the study is discussed. @JASEM Keyterms: Meat, Meat ball, Quality, Product development. J. Appl. Sci. Environ. Manage. June, 2012, Vol.

  11. The spectacle of the ball python (Python regius)

    DEFF Research Database (Denmark)

    Da Silva, Mari-Ann Otkjær; Heegaard, Steffen; Wang, Tobias

    2014-01-01

    A detailed morphological description of the spectacle of the ball python (Python regius) is provided. The eyes of 21 snakes were examined by light microscopy and/or transmission electron microscopy. Additionally, eyes of nine live snakes were examined using optical coherence tomography (OCT) and ...

  12. Severe wear behaviour of alumina balls sliding against diamond ...

    Indian Academy of Sciences (India)

    Alumina balls worn out ( 14.2 × 10 − 1 mm 3 ) very rapidly with zero wear for diamond ceramic coatings. Since the generation of wear particle is the main problem for load-bearing prosthetic joints, it was concluded that the PCD material can potentially replace existing alumina bio-ceramic for their bettertribological properties ...

  13. Preparation of iron sulphides by high energy ball milling

    DEFF Research Database (Denmark)

    Lin, R.; Jiang, Jianzhong; Larsen, R.K.

    1998-01-01

    The reaction of a powder mixture consisting of 50 a.% Fe and 50 a.% S during high energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. After around 19 h of milling FeS2 and FeS havebeen formed. By further milling the FeS compound becomes dominating and only Fe...

  14. 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 ca...

  15. Precession of a Spinning Ball Rolling down an Inclined Plane

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A routine problem in an introductory physics course considers a rectangular block at rest on a plane inclined at angle a to the horizontal. In order for the block not to slide down the incline, the coefficient of sliding friction, µ, must be at least tan a. The situation is similar for the case of a ball rolling down an inclined plane. In order…

  16. Rock Characteristics and Ball Mill Energy Requirements at ...

    African Journals Online (AJOL)

    Michael

    2015-06-01

    Jun 1, 2015 ... rate, power draw and ball mill performance. The rock types identified were conglomerate and quartzite and the main minerals were quartz, feldspars, iron oxides and sulphides. Mineralogical analysis classified the ores into hard, medium and soft. There were little differences in the mineral constituents of the ...

  17. 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.

  18. 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.

  19. High-Energy Ball-Milling of Alloys and Compounds

    International Nuclear Information System (INIS)

    Le Caer, G.; Delcroix, P.; Begin-Colin, S.; Ziller, T.

    2002-01-01

    After outlining some characteristics of high-energy ball-milling, we discuss selected examples of phase transformation and of alloy synthesis which focus on deviations from archetypal behaviours and throw light on the milling mechanisms. Some contributions of Moessbauer spectrometry to the characterization of ground materials are described.

  20. Design optimization of deep groove ball bearings using crowding ...

    Indian Academy of Sciences (India)

    Aparna Duggirala

    2018-02-07

    Feb 7, 2018 ... Abstract. This paper presents a crowding distance particle swarm optimization technique to optimize the design parameters of deep groove ball bearings. The design optimization problem is multi-objective in nature. The considered objectives are maximizing dynamic and static load bearing capacities and ...

  1. Differential effects of thermal and chemical stressors on tissue balls ...

    African Journals Online (AJOL)

    Coral cell aggregates (tissue balls) from four species (Acropora muricata, Fungia repanda, Pavona cactus and Pocillopora damicornis) were used as an indicator to investigate the effects on the corals of thermal stress and of chemical extracts from three sponges (Adocia sp., Haliclona sp. and Lissodendoryx sp.) and one ...

  2. Eric Cantona: Fußball-Ikone der modernen Medienwelt

    Directory of Open Access Journals (Sweden)

    Martin Wassermair

    2010-03-01

    Full Text Available In Unterhaltungsindustrie und Massenmedien nimmt der Sport eine im wahrsten Sinne des Wortes bewegende Rolle ein. Er ist zugleich Wettkampf-Arena und Wunschmaschine, Werbefläche und Starproduktion. Dass die Erscheinungsformen des Sports in der modernen Medienwelt einer rasanten Dynamik und Wechselbeziehung unterliegen, ist am Beispiel des Massenphänomens Fußballs vielleicht am deutlichsten abzulesen.

  3. Development of Microcontroller-Based Ball and Beam Trainer Kit

    Directory of Open Access Journals (Sweden)

    Gunawan Dewantoro

    2015-03-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE A ball and beam trainer kit based on microcontroller was developed for teaching control system course for the sophomore students. This specially-purposed kit consists of a ball located on a beam with a fixed axle at one of its end. At the other end, a servomotor was employed to control the position of the ball by adjusting the rotation angle of the servomotor. Seven predetermined positions were set to 10, 20, 30, 40, 50, 60, and 70 cm relative to the fixed axle of the beam. The Proportional-Integral-Derivative (PID scheme was then used to compensate the error. This kit is equipped with a user interface to configure controller coefficients, select the set points, plot the actual ball position, and display parameter values. The user interface program runs on PC or notebook connected to microcontroller via serial communications. A questionnaire-based assessment about the use of this kit was conducted by 17 students taking the course, giving a rating value of 94.12%.

  4. Brown carbon in tar balls from smoldering biomass combustion

    Science.gov (United States)

    R. K. Chakrabarty; H. Moosmuller; L.-W. A. Chen; K. Lewis; W. P. Arnott; C. Mazzoleni; M. K. Dubey; C. E. Wold; W. M. Hao; S. M. Kreidenweis

    2010-01-01

    We report the direct observation of laboratory production of spherical, carbonaceous particles - "tar balls" - from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Angstrom coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent...

  5. An earthworm-like robot using origami-ball structures

    Science.gov (United States)

    Fang, Hongbin; Zhang, Yetong; Wang, K. W.

    2017-04-01

    Earthworms possess extraordinary on-ground and underground mobility, which inspired researchers to mimic their morphology characteristics and locomotion mechanisms to develop crawling robots. One of the bottlenecks that constrain the development and wide-spread application of earthworm-like robots is the process of design, fabrication and assembly of the robot frameworks. Here we present a new earthworm-like robot design and prototype by exploring and utilizing origami ball structures. The origami ball is able to antagonistically output both axial and radial deformations, similar as an earthworm's body segment. The origami folding techniques also introduce many advantages to the robot development, including precise and low cost fabrication and high customizability. Starting from a flat polymer film, we adopt laser machining technique to engrave the crease pattern and manually fold the patterned flat film into an origami ball. Coupling the ball with a servomotor-driven linkage yields a robot segment. Connecting six segments in series, we obtain an earthworm-like origami robot prototype. The prototype is tested in a tube to evaluate its locomotion performance. It shows that the robot could crawl effectively in the tube, manifesting the feasibility of the origami-based design. In addition, test results indicate that the robot's locomotion could be tailored by employing different peristalsis-wave based gaits. The robot design and prototype reported in this paper could foster a new breed of crawling robots with simply design, fabrication, and assemble processes, and improved locomotion performance.

  6. Thump, ring: the sound of a bouncing ball

    Energy Technology Data Exchange (ETDEWEB)

    Katz, J I, E-mail: katz@wuphys.wustl.ed [Department of Physics and McDonnell Center for the Space Sciences, Washington University, St Louis, MO 63130 (United States)

    2010-07-15

    A basketball bounced on a stiff surface produces a characteristic loud thump, followed by a high-pitched ringing. Describing the ball as an inextensible but flexible membrane containing compressed air, I formulate an approximate theory of the generation of these sounds and predict their amplitudes and waveforms.

  7. Application of the Blobo bluetooth ball in wrist rehabilitation training.

    Science.gov (United States)

    Hsieh, Wei-Min; Hwang, Yuh-Shyan; Chen, Shih-Ching; Tan, Sun-Yen; Chen, Chih-Chen; Chen, Yu-Luen

    2016-01-01

    [Purpose] The introduction of emerging technologies such as the wireless Blobo bluetooth ball with multimedia features can enhance wrist physical therapy training, making it more fun and enhancing its effects. [Methods] Wrist injuries caused by fatigue at work, improper exercise, and other conditions are very common. Therefore, the reconstruction of wrist joint function is an important issue. The efficacy of a newly developed integrated wrist joint rehabilitation game using a Blobo bluetooth ball with C# software installed was tested in wrist rehabilitation (Flexion, Extension, Ulnar Deviation, Radial Deviation). [Results] Eight subjects with normal wrist function participated in a test of the system's stability and repeatability. After performing the Blobo bluetooth ball wrist physical therapy training, eight patients with wrist dysfunction experienced approximately 10° improvements in range of motion (ROM) of flexion extension, and ulnar deviation and about 6° ROM improvement in radial deviation. The subjects showed progress in important indicators of wrist function. [Conclusion] This study used the Blobo bluetooth ball in wrist physical therapy training and the preliminary results were encouraging. In the future, more diverse wrist or limb rehabilitation games should be developed to meet the needs of physical therapy training.

  8. Visual strategies underpinning the development of visual-motor expertise when hitting a ball

    NARCIS (Netherlands)

    Sarpeshkar, Vishnu; Abernethy, B.; Mann, D.L.

    2017-01-01

    It is well known that skilled batters in fast-ball sports do not align their gaze with the ball throughout ball-flight, but instead adopt a unique sequence of eye and head movements that contribute toward their skill. However, much of what we know about visual-motor behavior in hitting is based on

  9. Rolling Motion of a Ball Spinning about a Near-Vertical Axis

    Science.gov (United States)

    Cross, Rod

    2012-01-01

    A ball that is projected forward without spin on a horizontal surface will slide for a short distance before it starts rolling. Sliding friction acts to decrease the translation speed v and it acts to increase the rotation speed [omega]. When v = R[omega], where R is the ball radius, the ball will start rolling and the friction force drops almost…

  10. 78 FR 33975 - Safety Zone; Flagship Niagara Mariners Ball Fireworks, Presque Isle Bay, Erie, PA

    Science.gov (United States)

    2013-06-06

    ...-AA00 Safety Zone; Flagship Niagara Mariners Ball Fireworks, Presque Isle Bay, Erie, PA AGENCY: Coast... Presque Isle Bay during the Flagship Niagara Mariners Ball Fireworks display. This temporary safety zone... the Flagship Niagara Mariners Ball Fireworks. This zone will be effective and enforced from 9:30 p.m...

  11. 78 FR 9674 - Ball Bearings and Parts Thereof From Germany: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2013-02-11

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-428-801] Ball Bearings and Parts... antidumping duty order on ball bearings and parts thereof from Germany. The period of review (POR) is May 1... at less than normal value. \\1\\ On September 15, 2011, the Department revoked the order on ball...

  12. 27 CFR 25.293 - Record of ballings and alcohol content.

    Science.gov (United States)

    2010-04-01

    ... TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Records and Reports § 25.293 Record of ballings... the ballings and the alcohol content of beer and cereal beverage transferred for bottling and racking, between breweries in bulk conveyances, and to pilot brewing plants. Records showing ballings and alcohol...

  13. Effects of Caffeine Supplementation on Performance in Ball Games.

    Science.gov (United States)

    Chia, Jingyi Shannon; Barrett, Laura Ann; Chow, Jia Yi; Burns, Stephen Francis

    2017-12-01

    Although a large body of evidence exists documenting the ergogenic properties of caffeine, most studies have focused on endurance performance. However, findings from endurance sports cannot be generalized to performance in ball games where, apart from having a high level of endurance, successful athletic performances require a combination of physiological, technical and cognitive capabilities. The purpose of this review was to critically evaluate studies that have examined the effect of a single dose of caffeine in isolation on one or more of the following performance measures: total distance, sprint performance, agility, vertical jump performance and accuracy in ball games. Searches of three major databases resulted in 19 studies (invasion games: 13; net-barrier games: 6) that evaluated the acute effects of caffeine on human participants, provided the caffeine dose administered, and included a ball games specific task or simulated match. Improvements in sprint performance were observed in 8 of 10 studies (80%), and vertical jump in 7 of 8 studies (88%). Equivocal results were reported for distance covered, agility and accuracy. Minor side effects were reported in 4 of 19 studies reviewed. Pre-exercise caffeine ingestion between 3.0 and 6.0 mg/kg of body mass appears to be a safe ergogenic aid for athletes in ball games. However, the efficacy of caffeine varies depending on various factors, including, but not limited to, the nature of the game, physical status and caffeine habituation. More research is warranted to clarify the effects of caffeine on performance measures unique to ball games, such as agility and accuracy. It is essential that athletes, coaches and practitioners evaluate the risk-benefit ratio of caffeine ingestion strategies on an individual case-by-case basis.

  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. Ball-milled sulfur-doped graphene materials contain metallic impurities originating from ball-milling apparatus: their influence on the catalytic properties.

    Science.gov (United States)

    Chua, Chun Kiang; Sofer, Zdeněk; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2016-07-21

    Graphene materials have found applications in a wide range of devices over the past decade. In order to meet the demand for graphene materials, various synthesis methods are constantly being improved or invented. Ball-milling of graphite to obtain graphene materials is one of the many versatile methods to easily obtain bulk quantities. In this work, we show that the graphene materials produced by ball-milling are spontaneously contaminated with metallic impurities originating from the grinding bowls and balls. Ball-milled sulfur-doped graphene materials obtained from two types of ball-milling apparatus, specifically made up of stainless steel and zirconium dioxide, were investigated. Zirconium dioxide-based ball-milled sulfur-doped graphene materials contain a drastically lower amount of metallic impurities than stainless steel-based ball-milled sulfur-doped graphene materials. The presence of metallic impurities is demonstrated by their catalytic effects toward the electrochemical catalysis of hydrazine and cumene hydroperoxide. The general impression toward ball-milling of graphite as a versatile method for the bulk production of 'metal-free' graphene materials without the need for post-processing and the selection of ball-milling tools should be cautioned. These findings would have wide-reaching implications for graphene research.

  16. Characterization of Ball Milled Al-Al2O3 sub-micron Composites

    Science.gov (United States)

    Dagasan, E.; Gercekcioglu, E.; Unalan, S.

    2018-01-01

    The purpose of this study is to investigate properties of the composite powders produced by ball milling process. Different weight ratio of high purity Al2O3 powders were added to the Al matrix as reinforcing element. Ball milling process was conducted by a planetary type ball mill with WC milling balls and vial at constant parameters like rotating speed, time, Ball-to-Powder ratio and Process Control Agent. Samples that taken from the powder mixtureby various time intervals were analyzed by SEM, XRD and BET surface area and porosity measurement systems.

  17. Analysis on Sealing Reliability of Bolted Joint Ball Head Component of Satellite Propulsion System

    Science.gov (United States)

    Guo, Tao; Fan, Yougao; Gao, Feng; Gu, Shixin; Wang, Wei

    2018-01-01

    Propulsion system is one of the important subsystems of satellite, and its performance directly affects the service life, attitude control and reliability of the satellite. The Paper analyzes the sealing principle of bolted joint ball head component of satellite propulsion system and discuss from the compatibility of hydrazine anhydrous and bolted joint ball head component, influence of ground environment on the sealing performance of bolted joint ball heads, and material failure caused by environment, showing that the sealing reliability of bolted joint ball head component is good and the influence of above three aspects on sealing of bolted joint ball head component can be ignored.

  18. Acoustic evaluation of concrete delaminations using ball-chain impact excitation.

    Science.gov (United States)

    Sun, Hongbin; Zhu, Jinying; Ham, Suyun

    2017-05-01

    This letter presents an automated acoustic sensing device for rapid detection of delamination in concrete. The device consists of ball-chains for continual impact excitation and multi-channel microphones for acoustic sensing. A ball-chain is formed by multiple metal balls connected by flexible ropes and is dragged on concrete surface to excite vibration of delaminations. Compared to the conventional chain drag test, the ball-chain generates acoustic signals with higher signal-to-noise ratio (S/N) because the balls give isolated but continual impacts on concrete surface during dragging. The proposed method was validated on a concrete specimen with artificial delaminations.

  19. Fuzzy Logic Control of a Ball on Sphere System

    Directory of Open Access Journals (Sweden)

    Seyed Alireza Moezi

    2014-01-01

    Full Text Available The scope of this paper is to present a fuzzy logic control of a class of multi-input multioutput (MIMO nonlinear systems called “system of ball on a sphere,” such an inherently nonlinear, unstable, and underactuated system, considered truly to be two independent ball and wheel systems around its equilibrium point. In this work, Sugeno method is investigated as a fuzzy controller method, so it works in a good state with optimization and adaptive techniques, which makes it very attractive in control problems, particularly for such nonlinear dynamic systems. The system’s dynamic is described and the equations are illustrated. The outputs are shown in different figures so as to be compared. Finally, these simulation results show the exactness of the controller’s performance.

  20. Coefficient of restitution of sports balls: A normal drop test

    Science.gov (United States)

    Haron, Adli; Ismail, K. A.

    2012-09-01

    Dynamic behaviour of bodies during impact is investigated through impact experiment, the simplest being a normal drop test. Normally, a drop test impact experiment involves measurement of kinematic data; this includes measurement of incident and rebound velocity in order to calculate a coefficient of restitution (COR). A high speed video camera is employed for measuring the kinematic data where speed is calculated from displacement of the bodies. Alternatively, sensors can be employed to measure speeds, especially for a normal impact where there is no spin of the bodies. This paper compares experimental coefficients of restitution (COR) for various sports balls, namely golf, table tennis, hockey and cricket. The energy loss in term of measured COR and effects of target plate are discussed in relation to the material and construction of these sports balls.

  1. Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling.

    Science.gov (United States)

    Jicsinszky, László; Caporaso, Marina; Calcio Gaudino, Emanuela; Giovannoli, Cristina; Cravotto, Giancarlo

    2017-03-19

    A number of influencing factors mean that the random substitution of cyclodextrins (CD) in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent's hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS) with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

  2. Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling

    Directory of Open Access Journals (Sweden)

    László Jicsinszky

    2017-03-01

    Full Text Available A number of influencing factors mean that the random substitution of cyclodextrins (CD in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent’s hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

  3. Magnet balls stuck to the frenulum of the lip.

    Science.gov (United States)

    Kondamudi, Noah P; Ayush Gupta; Kaur, Ranbir

    2014-03-01

    Accidents associated with magnets as foreign bodies pose a serious threat to the health of children and adolescents. Prompt management and removal of the magnet is important to avoid life-threatening complications. Our aim was to highlight an unusual health hazard associated with magnets in children. We report on a unique case of an adolescent girl who presented with two magnet balls stuck to the frenulum of her upper lip, resulting in intense pain and discomfort. The magnets were removed painlessly by induced magnetism through metallic mosquito forceps. As children experiment with toys and products containing detachable magnetic balls, more cases will likely present to emergency departments. Increased awareness and preventive measures should be undertaken to reduce the morbidity and mortality associated with magnets. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Sir Robert Ball: Victorian Astronomer and Lecturer par excellence

    Science.gov (United States)

    Jones, R. I. G.

    2005-12-01

    Between 1875 and 1910 Sir Robert Stawell Ball gave an estimated 2,500 lectures in towns and cities all over the British Isles and abroad. This paper traces his lecturing career from its beginnings in Ireland to the triumphs of the Royal Institution, and on lecture tours in the United States of America. After a period in mathematics and mechanics, he became a populariser of science, especially astronomy, and found fame and fortune among the working classes and the aristocracy. What motivated him to tireless travels is uncertain, but it might have been that it was rewarding, financially and to his reputation. Whatever his motives, contemporary accounts are clear that BallÕs lectures were extremely popular and well-received.

  5. Coefficient of restitution of sports balls: A normal drop test

    International Nuclear Information System (INIS)

    Haron, Adli; Ismail, K A

    2012-01-01

    Dynamic behaviour of bodies during impact is investigated through impact experiment, the simplest being a normal drop test. Normally, a drop test impact experiment involves measurement of kinematic data; this includes measurement of incident and rebound velocity in order to calculate a coefficient of restitution (COR). A high speed video camera is employed for measuring the kinematic data where speed is calculated from displacement of the bodies. Alternatively, sensors can be employed to measure speeds, especially for a normal impact where there is no spin of the bodies. This paper compares experimental coefficients of restitution (COR) for various sports balls, namely golf, table tennis, hockey and cricket. The energy loss in term of measured COR and effects of target plate are discussed in relation to the material and construction of these sports balls.

  6. Characterizations of Sobolev spaces via averages on balls

    Czech Academy of Sciences Publication Activity Database

    Dai, F.; Gogatishvili, Amiran; Yang, D.; Yuan, W.

    2015-01-01

    Roč. 128, November (2015), s. 86-99 ISSN 0362-546X R&D Projects: GA ČR GA13-14743S Institutional support: RVO:67985840 Keywords : Sobolev space * average on ball * difference * Euclidean space * space of homogeneous type Subject RIV: BA - General Math ematics Impact factor: 1.125, year: 2015 http://www.sciencedirect.com/science/article/pii/S0362546X15002618

  7. Unexpected Expectations The Curiosities of a Mathematical Crystal Ball

    CERN Document Server

    Wapner, Leonard M

    2012-01-01

    Unexpected Expectations: The Curiosities of a Mathematical Crystal Ball explores how paradoxical challenges involving mathematical expectation often necessitate a reexamination of basic premises. The author takes you through mathematical paradoxes associated with seemingly straightforward applications of mathematical expectation and shows how these unexpected contradictions may push you to reconsider the legitimacy of the applications. The book requires only an understanding of basic algebraic operations and includes supplemental mathematical background in chapter appendices. After a history o

  8. Tracking of Ball and Players in Beach Volleyball Videos

    OpenAIRE

    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, respec...

  9. Condition monitoring of thrust ball bearings using continuous AE

    Czech Academy of Sciences Publication Activity Database

    Chlada, Milan; Nohal, L.; Převorovský, Zdeněk

    2016-01-01

    Roč. 26, č. 2 (2016), A14-A14 ISSN 1213-3825. [Europen Conference on Acoustic Emission Testing /32./. 07.09.2016-09.09.2016, Praha] Grant - others:NETME Centre Plus - národní program udržitelnosti(CZ) LO1202 Institutional support: RVO:61388998 Keywords : continuous acoustic emission * rolling contact fatigue * thrust ball bearing * histogram of counting periods * wavelet analysis Subject RIV: BI - Acoustics

  10. Efficacy of birth ball exercises on labour pain management.

    Science.gov (United States)

    Leung, R W C; Li, J F P; Leung, M K M; Fung, B K Y; Fung, L C W; Tai, S M; Sing, C; Leung, W C

    2013-10-01

    To evaluate the efficacy of a birth ball exercise programme conducted by physiotherapists on pain relief, psychological care, and facilitation of the labour process at a labour ward in a regional hospital. Case series with before-after comparisons. Kwong Wah Hospital, Hong Kong. Chinese women admitted to the labour ward for spontaneous vaginal delivery between April and August 2012 were recruited. Physiotherapists taught birth ball exercises in groups or individually for 30 minutes. Labour pain intensity, back pain intensity, frequency of labour pain, stress and anxiety levels, and subjective pressure level over the lower abdomen were captured before and after birth ball exercises. Most of the parameters were measured using self-reported visual analogue scales. After the exercise session, physiotherapists measured the women's satisfaction level. Midwives recorded pethidine usage. A total of 203 pregnant women participated in this programme; 181 were in the latent phase group, whereas 22 were categorised into the no-labour-pain group. In both groups, there were statistically and clinically significant differences in back pain level, stress and anxiety levels, as well as pressure level over the lower abdomen before and after the exercise (Plabour pain and frequency of labour pain were demonstrated. Mean satisfaction scores were high, with visual analogue scale scores higher than 8.2 in both groups. Pethidine usage showed a further decreasing trend (6.4%) compared with the past 2 years. Birth ball exercise could be an alternative means of relieving back pain and labour pain in the labour ward, and could decrease pethidine consumption in labouring women.

  11. Spatiotemporal characteristics of muscle patterns for ball catching

    Directory of Open Access Journals (Sweden)

    Mattia eD'Andola

    2013-08-01

    Full Text Available What sources of information and what control strategies the CNS uses to perform movements that require accurate sensorimotor coordination, such as catching a flying ball, is still debated. Here we analyzed the EMG waveforms recorded from 16 shoulder and elbow muscles in six subjects during catching of balls projected frontally from a distance of 6 m and arriving at two different heights and with three different flight times (550, 650, 750 ms. We found that a large fraction of the variation in the muscle patterns was captured by two time-varying muscle synergies, coordinated recruitment of groups of muscles with specific activation waveforms, modulated in amplitude and shifted in time according to the ball’s arrival height and flight duration. One synergy was recruited with a short and fixed delay from launch time. Remarkably, a second synergy was recruited at a fixed time before impact, suggesting that it is timed according to an accurate time-to-contact estimation. These results suggest that the control of interceptive movements relies on a combination of reactive and predictive processes through the intermittent recruitment of time-varying muscle synergies. Knowledge of the dynamic effect of gravity and drag on the ball may be then implicitly incorporated in a direct mapping of visual information into a small number of synergy recruitment parameters.

  12. Experimental Study on Voided Reinforced Concrete Beams with Polythene Balls

    Science.gov (United States)

    Sivaneshan, P.; Harishankar, S.

    2017-07-01

    The primary component in any structure is concrete, that exist in buildings and bridges. In present situation, a serious problems faced by construction industry is exhaustive use of raw materials. Recent times, various methods are being adopted to limit the use of concrete. In structural elements like beams, polythene balls can be induced to reduce the usage of concrete. A simply supported reinforced concrete beam has two zones, one above neutral axis and other below neutral axis. The region below neutral axis is in tension and above neutral axis is in compression. As concrete is weak in tension, steel reinforcements are provided in tension zone. The concrete below the neutral axis acts as a stress transfer medium between the compression zone and tension zone. The concrete above the neutral axis takes minimum stress so that we could partially replace the concrete above neutral axis by creating air voids using recycled polythene balls. Polythene balls of varying diameters of 75 mm, 65 mm and 35 mm were partially replaced in compression zone. Hence the usage of concrete in beams and self-weight of the beams got reduced considerably. The Load carrying capacity, Deflection of beams and crack patterns were studied and compared with conventional reinforced concrete beams.

  13. Finite element analysis of thrust angle contact ball slewing bearing

    Science.gov (United States)

    Deng, Biao; Guo, Yuan; Zhang, An; Tang, Shengjin

    2017-12-01

    In view of the large heavy slewing bearing no longer follows the rigid ring hupothesis under the load condition, the entity finite element model of thrust angular contact ball bearing was established by using finite element analysis software ANSYS. The boundary conditions of the model were set according to the actual condition of slewing bearing, the internal stress state of the slewing bearing was obtained by solving and calculation, and the calculated results were compared with the numerical results based on the rigid ring assumption. The results show that more balls are loaded in the result of finite element method, and the maximum contact stresses between the ball and raceway have some reductions. This is because the finite element method considers the ferrule as an elastic body. The ring will produce structure deformation in the radial plane when the heavy load slewing bearings are subjected to external loads. The results of the finite element method are more in line with the actual situation of the slewing bearing in the engineering.

  14. Abstract of reports on operating experiences with ball kilns

    Energy Technology Data Exchange (ETDEWEB)

    1943-11-05

    The first items discussed were the drums and this included discussion of linings, outlet-opening sizes and shapes, and the filling of the drum. The drum drive was recommended to be a high-speed squirrel cage motor with a Cycle-drive with a flanged-on-motor as an emergency drive. A discharge device, cranes, drum heating, preheating, steam superheater, temperatures, condensation, and disposal of the residue were also topics of discussion. Me 884 produced about 2000 tons of desanding residue monthly with 25% to 30% heavy oil. This heavy oil went to the dump with the sand. About 80% of this heavy oil could be recovered by carbonization. For this purpose, a kiln with the necessary conveying equipment was necessary. A description of this process was given. A flow sheet of processing filter residue from desanding was also given. Sludge carbonization in the ball kiln was also necessary. The ball kilns, as well as the screw kilns, were intended for the carbonization of the coal stall sludge and the residue from the carbonization centrifuges. The plant consisted of three main parts: the kiln, the discharge equipment for the carbonized residue, and the condensation for the oil and water vapors produced. A flow sheet of sludge carbonization in a ball kiln was given. 2 sketches.

  15. Decomposition of intermetallics during high-energy ball-milling

    International Nuclear Information System (INIS)

    Kwon, Y.S.; Choi, P.P.; Kim, J.S.; Kwon, D.H.; Gerasimov, K.B.

    2007-01-01

    The decomposition behavior of FeSn, CoSn and CoIn 2 intermetallics under high-energy ball-milling has been investigated using X-ray diffraction, calorimetric and magnetization measurements. Upon milling a large amount of the FeSn intermetallic decomposes into Fe 5 Sn 3 and FeSn 2 , where the average grain size of the product phases stays nearly constant with milling-time. Similar observations are made for the CoSn intermetallic, which decomposes into Co 3 Sn 2 and Sn. It is suggested that the mechanically driven decomposition of FeSn and CoSn results from local melting of powder particles due to high temperature pulses during ball collisions. In contrast to FeSn and CoSn, CoIn 2 does not undergo decomposition upon milling. The different decomposition behaviors of the studied intermetallics may be attributed to the volume changes occurring with a decomposition process. Whereas a negative volume change is associated with the decomposition of FeSn and CoSn into their product phases, the decomposition of CoIn 2 leads to an increase in volume. Hence, high local stresses under ball collisions are expected to make the mechanically induced decomposition of FeSn and CoSn favorable but rather hinder the decomposition of CoIn 2

  16. Lift crisis of a spinning table tennis ball

    Science.gov (United States)

    Miyazaki, T.; Sakai, W.; Komatsu, T.; Takahashi, N.; Himeno, R.

    2017-03-01

    The aerodynamic properties of a spinning table tennis ball were investigated using flight experiments. Using high-speed video cameras, the trajectory and rotation of an official ball (Nittaku 3-Star Premium), which was launched by a three rotor machine, were recorded. The drag and lift coefficients (C D and C L) were determined by analysing the video images. The measurements covered the speed and rotation range of typical table tennis shots in the form of the Reynolds number (Re) and dimensionless spin rate (SP), i.e. 3.0 × 104 < Re < 9.0 × 104 and 0 < SP < 1.0, and C D and C L were obtained as functions of Re and SP. We determined that the lift coefficient C L is not a monotonically increasing function of SP. A deep valley of C L was found around SP = 0.5, and the lift force exerted on a spinning ball almost vanished at Re = 9.0 × 104 and 0.48 < SP < 0.5. These results qualitatively agree with the results from recent wind tunnel tests, but quantitative differences owing to the unsteady nature of the flight experiments remain. This anomaly in the lift coefficient should be called the ‘lift crisis’.

  17. Brown carbon in tar balls from smoldering biomass combustion

    Science.gov (United States)

    Chakrabarty, R. K.; Moosmüller, H.; Chen, L.-W. A.; Lewis, K.; Arnott, W. P.; Mazzoleni, C.; Dubey, M. K.; Wold, C. E.; Hao, W. M.; Kreidenweis, S. M.

    2010-07-01

    We report the direct observation of laboratory production of spherical, carbonaceous particles - "tar balls" - from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Ångström coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent imaginary part of its refractive index - optically defined as "brown carbon" - is an important component of tar balls. The spectrum of the imaginary parts of their complex refractive indices can be described with a Lorentzian-like model with an effective resonance wavelength in the ultraviolet (UV) spectral region. Sensitivity calculations for aerosols containing traditional OC (no absorption at visible and UV wavelengths) and brown carbon suggest that accounting for near-UV absorption by brown carbon leads to an increase in aerosol radiative forcing efficiency and increased light absorption. Since particles from smoldering combustion account for nearly three-fourths of the total carbonaceous aerosol mass emitted globally, inclusion of the optical properties of tar balls into radiative forcing models has significance for the Earth's radiation budget, optical remote sensing, and understanding of anomalous UV absorption in the troposphere.

  18. Brown carbon in tar balls from smoldering biomass combustion

    Directory of Open Access Journals (Sweden)

    R. K. Chakrabarty

    2010-07-01

    Full Text Available We report the direct observation of laboratory production of spherical, carbonaceous particles – "tar balls" – from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption Ångström coefficients (AAC indicate that a class of light absorbing organic carbon (OC with wavelength dependent imaginary part of its refractive index – optically defined as "brown carbon" – is an important component of tar balls. The spectrum of the imaginary parts of their complex refractive indices can be described with a Lorentzian-like model with an effective resonance wavelength in the ultraviolet (UV spectral region. Sensitivity calculations for aerosols containing traditional OC (no absorption at visible and UV wavelengths and brown carbon suggest that accounting for near-UV absorption by brown carbon leads to an increase in aerosol radiative forcing efficiency and increased light absorption. Since particles from smoldering combustion account for nearly three-fourths of the total carbonaceous aerosol mass emitted globally, inclusion of the optical properties of tar balls into radiative forcing models has significance for the Earth's radiation budget, optical remote sensing, and understanding of anomalous UV absorption in the troposphere.

  19. Ultrasonic friction power during thermosonic Au and Cu ball bonding

    International Nuclear Information System (INIS)

    Shah, A; Mayer, M; Zhou, Y; Qin, I; Huynh, C; Meyer, M

    2010-01-01

    The ultrasonic friction power during thermosonic ball bonding with Au and Cu wires, both 25 μm in diameter, is derived with an improved method from experimental measurements during the bonding process. Experimental data include the current delivered to the ultrasonic transducer and the tangential force measured using piezoresistive microsensors integrated close to the Al bonding pad. The improvement results from a new, more accurate method to derive the mechanical compliance of the ultrasonic system. The method employs a bond process modification in which the ultrasonic current is ramped up sequentially in three steps. In the first two steps, the ultrasonic current is set to levels that are too low to cause sliding. The bonding takes place during the third step, when the current is ramped up to the optimum value required for making good quality bonds. The ultrasonic compliance values are derived from the first two steps and are 8.2 ± 0.5 μm N -1 and 7.7 ± 0.5 μm N -1 for the Au and Cu processes, respectively. These values are determined within an average error estimate of ±6%, substantially lower than the ±10% estimated with a previously reported method. The ultrasonic compliance in the case of Au is 6% higher due to the lower elastic modulus of Au compared with that of Cu. Typical maximum values of relative sliding amplitude of ultrasonic friction at the interface are 655 nm and 766 nm for the Au and Cu processes. These values are 81% of the free-air vibration amplitude of the bonding capillary tip for the respective ultrasonic current settings. Due to bond growth, which damps relative motion between the ball and the pad, the final relative amplitude at the bond interface is reduced to 4% of the equivalent free-air amplitude. Even though the maximum value of relative amplitude is 17% higher in the Cu process compared with the Au process, the average total interfacial sliding is 519 μm in the Cu process, which is 31% lower than that in the Au process (759

  20. The effect of ball compression on the match-play characteristics of elite junior tennis players.

    Science.gov (United States)

    Kachel, Kim; Buszard, Tim; Reid, Machar

    2015-01-01

    The purpose of this article was to examine the effect of equipment scaling, through the modification of tennis ball compression, on elite junior tennis players (aged 10 years) within a match-play context. The two types of ball compressions that were compared were the standard compression (the normal ball) and 75% compression (termed the modified ball). Ten boys and 10 girls participated in the study. Participants were stratified into pairs based on their Australian Age Ranking and gender. Each pair played two two-set matches: one match with standard compression balls and one match with modified balls. The characteristics of each match were analysed and compared. The results showed that the use of the modified ball increased rally speed, allowed players to strike the ball at a lower (more comfortable) height on their groundstrokes and increased the number of balls played at the net. Ball compression had no effect on the relative number of winners, forehands, backhands, first serves in and double faults. The results are discussed in relation to skill acquisition for skilled junior tennis players.

  1. An improved effective microorganism (EM) soil ball-making method for water quality restoration.

    Science.gov (United States)

    Park, Gun-Seok; Khan, Abdur Rahim; Kwak, Yunyoung; Hong, Sung-Jun; Jung, ByungKwon; Ullah, Ihsan; Kim, Jong-Guk; Shin, Jae-Ho

    2016-01-01

    Soil balls containing the so-called effective microorganisms (EM) have been applied to improve water quality of small ponds, lakes, and streams worldwide. However, neither the physical conditions facilitating their proper application nor the diversity of microbial community in such soil balls have been investigated. In this study, the application of 0.75% of hardener to the soil balls exerted almost neutral pH (pH 7.3) which caused up to a fourfold increased hardness of the soil ball. Moreover, the 0.75% of hardener in the soil ball also improved the water quality due to a significant reduction in dissolved oxygen, total phosphorus, and total nitrogen contents. Metagenomic analysis of the microbial community in the soil ball with 0.75% hardener was compared with control (traditional soil ball) through next-generation sequencing. The traditional soil ball microbial community comprised 96.1% bacteria, 2.7% eukaryota, and 1% archaea, whereas the soil ball with 0.75% hardener comprised 71.4% bacteria, 27.9% eukaryota, and 0.2% viruses. Additionally, metagenomic profiles for both traditional and improved soil balls revealed that the various xenobiotic biodegradation, such as those for caprolactam, atrazine, xylene, toluene, styrene, bisphenol, and chlorocyclohexane might be responsible for organic waste cleanup.

  2. 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.

  3. A Method to Determine the Ball Filling, in Miduk Copper Concentrator SAG Mill

    Directory of Open Access Journals (Sweden)

    Ali Kamali Moaveni

    2012-12-01

    Full Text Available The aim of this research work was to investigate on the ball filling estimation of Miduk semi-autogenous (SAG Mill via an utilized method. Miduk copper concentrator is located in Kerman Province, Iran, and its size reduction stage includes one gyratory crusher which feeds one SAG mill (9.75 dia.(m*3.88 length(m following two parallel ball mills (5dia.(m*7lenght(m. After SAG mill, a trommel screen produces two over and under size materials which the oversize part is circulated into SAG mill and undersize reports to hydrocyclone for further process. Ball filling identify was implemented in this work using mill`s load sampling and ball abrasion test.These methods could estimate ball filling variation with easy, undeniable, and useful tests. Also, these tests have shown the digression of operating ball filling amount and its manual designed. To make more homogenous load, mill load samplings were carried out from 6 points after whirling the mill via inching motor. Acquired load sampling results were compared with ball abrasion tests. Ball abrasion tests were calculated for 3 different conditions include maximum, average, and minimum ball abrasion. However, the calculated maximum and minimum conditions never occurred. However, these are just for obtaining to ball filling variation in the mill. The results obtained from this work show, the ball filling percentage variation is between 1.2– 3.7% which is lower than mill ball filling percentage, according to the designed conditions (15%. In addition, acquired load samplings result for mill ball filling was 1.3%.

  4. Ball Throwing Without a Ball: Pantomimed Motor Execution Primes the Imagination That an Object is Traveling the Required Distance.

    Science.gov (United States)

    Tanaka, Hideyuki; Mizuno, Wataru; Iwami, Masato

    2016-10-01

    This study used a pantomime paradigm to investigate whether simulated motor actions are generally effective in estimating the force necessary to accurately drive an object toward the required target. Eleven subjects were asked to vertically throw a rubber ball toward three different targets and then catch it, all while sitting in a chair (ACT). In addition, they performed the same task under a condition whereby mechanical interactions with the rubber ball were minimized. This condition encompassed two different modes: pantomime (PANTO) and imagination without swings (IMAGE). PANTO reproduced the motor patterns observed during ACT. The maximum amplitudes and maximum accelerations of the upward swing movements scaled well in linear proportion to the target distances, although the maximum accelerations were significantly smaller than those in the ACT trials. IMAGE led to the overestimation of the ball's flight time, which is represented by the release-catch intervals. PANTO significantly reduced this tendency. These results suggest that pantomimed motor execution can prime more realistic mental simulations of object motion when compared with purely imagined motor execution.

  5. Kicking velocity and effect on match performance when using a smaller, lighter ball in women's football

    DEFF Research Database (Denmark)

    Andersen, Thomas B.; Krustrup, Peter; Bendiksen, Mads

    2016-01-01

    in passing success rate (NB: 68±1% and SB: 68±1%, p>0.05). In conclusion, high-level adult female footballers had a higher kicking speed when using a smaller, lighter ball, but no differences were observed during match-play with the 2 ball types in respect of technical-tactical and physical match performance......The present study evaluated the effect of a smaller, lighter ball on kicking speed and technical-tactical and physical match performance in high-level adult female footballers. In the laboratory test setting, the peak ball velocity was 6% higher with the new ball (NB) than the standard ball (SB.......08±0.42 and 1.94±0.38 km; p>0.05) and match-induced decrement in Yo-Yo IR1 performance (28 vs. 31%, respectively, p

  6. Ball-on-DiscTribometers Protocol Development: Loss of Lubrication Evaluation

    Science.gov (United States)

    2016-02-01

    average of the ball’s and disc’s linear velocities. The slip percentage is shown in Eq. 1. The ball thermocouple (Tb) and disc thermocouple ( Td ...surfaces rubbed against each other until the head of the bolt was caught on the top of the oil slinger and broke the screw at its connection to the spindle...single-tooth load capacity Tb ball thermocouple TC thermocouple Td disc thermocouple Ub ball linear velocity Ud disc linear velocity Ue

  7. Biomechanical predictors of ball velocity during punt kicking in elite rugby league kickers

    OpenAIRE

    Sinclair, Jonathan Kenneth; Taylor, Paul John; Atkins, Stephen; Hobbs, Sarah Jane

    2016-01-01

    Punt kicking is integral to the attacking and defensive elements of rugby league and the ability to kick the ball with high\\ud velocity is desirable. This study aimed to identify important technical aspects of kicking linked to the generation of ball\\ud velocity. Maximal punt kicks were obtained from six elite rugby league kickers using a 10-camera motion capture system.\\ud Three-dimensional kinematics of the lower extremities was obtained. Regression analysis with ball velocity as criterion\\...

  8. On the stability of a very dense deuterium-tritium plasma ball

    OpenAIRE

    Kornyushin, Yuri

    2010-01-01

    General conditions of stability of a very dense deuterium-tritium plasma ball are discussed. It is shown that the decrease in the size of a plasma ball (increase in the plasma density) can be expected only when the temperature and the pressure in the plasma ball are kept high enough for all the particles, the nuclei and the delocalized electrons, to be described by classical statistics.

  9. Pengaruh Slot Rugby Ball Terhadap Antena Mikrostrip Sehingga Dapat Bekerja Pada Ultra Wideband (UWB)

    OpenAIRE

    M. Fauzan Edy Purnomo, ST., MT., Prilla Ayu Wendaria., Rudy Yuwono, ST., M.Sc

    2013-01-01

    Penelitian ini membahas tentang pengaruh slot rugby ball pada antena mikrostrip annular ring sehingga dapat bekerja pada ultra wideband (UWB). Antena mikrostrip annular ring dengan slot rugby ball ini dirancang dengan menggunakan feed line sebagai metode pencatuannya. Dimensi antena diperoleh melalui perhitungan dan optimasi serta dilakukan simulasi dengan menggunakan software HFSS AnsoftTM versi 13. Hasil simulasi antena mikrostrip annular ring dengan slot rugby ball menunjukkan frekuensi ...

  10. Sports selection of volley-ball players: genetic criteria to define motor endowments (information 2)

    OpenAIRE

    Ablikovа, Alisa; Serhiyenko, Leonid

    2016-01-01

    Purpose: to define genetic criteria which can be used while selecting gifted volley-ball players. Material & Methods: the study involved 50 high class volley-ball players and 50 women at the age of 20–29 years old. There were used methods of theoretical analysis and general conclusion, systematic analysis, genealogic methods of genetics, methods of dermatoglyphic and serologic analyses. Results: family gift for going in for sport was detected. At was revealed that gifted volley-ball playe...

  11. Radiologic characteristics of sinonasal fungus ball: an analysis of 119 cases

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Young-Joon; Kim, Kyubo (Dept. of Otorhinolaryngology, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)); Kim, Jinna (Dept. of Radiology, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)); Lee, Jeung-Gweon; Kim, Chang-Hoon (Dept. of Otorhinolaryngology, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of); The Airway Mucus Institute, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)), email: entman@yuhs.ac; Yoon, Joo-Heon (Dept. of Otorhinolaryngology, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of); The Airway Mucus Institute, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of); Research Center for Human Natural Defense System, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of); BK21 Project for Medical Science, Yonsei Univ. College of Medicine, Seoul (Korea, Republic of))

    2011-09-15

    Background. It is important to differentiate sinonasal fungus ball from non-fungal sinusitis and other forms of fungal sinusitis in order to determine the optimal treatment. In particular, a sinonasal fungus ball, a non-invasive fungal sinusitis, can be characterized by radiologic findings before surgery. Purpose. To differentiate a sinonasal fungus ball from other types of sinusitis and determine optimal treatment on the basis of radiologic findings before surgery. Material and Methods. We studied 119 patients with clinically and pathologically proven sinonasal fungus balls. Their condition was evaluated radiologically with contrast-enhanced CT (99 patients), non-contrast CT (18 patients) and/or MRI (17 patients) prior to sinonasal surgery. Results. Calcifications were found in 78 of 116 (67.2%) patients who underwent CT scans for fungus ball. As opposed to non-contrast CT scans, contrast CT scans revealed hyper attenuating fungal ball in 82.8% and enhanced inflamed mucosa in 65.5% of the patients, respectively. On MRI, most sinonasal fungal balls showed iso- or hypointensity on T1-weighted images and marked hypointensity on T2-weighted images. Inflamed mucosal membranes were noted and appeared as hypointense on T1-weighted images (64.7%) and hyperintense on T2-weighted images (88.2%). Conclusion. When there are no calcifications visible on the CT scan, a hyper attenuating fungal ball located in the central area of the sinus with mucosal thickening on enhanced CT scans is an important feature of a non-invasive sinonasal fungus ball. On MRI, a sinonasal fungus ball has typical features of a marked hypointense fungus ball with a hyperintense mucosal membrane in T2-weighted images. A contrast-enhanced CT scan or MRI provides sufficient information for the preoperative differentiation of a sinonasal fungus ball from other forms of sinusitis

  12. Fabrication and Study of Micro Monolithic Tungsten Ball Tips for Micro/Nano-CMM Probes

    OpenAIRE

    Ruijun Li; Chen Chen; Kuangchao Fan; Zhiwei Wang; Fangfang Liu; Qiangxian Huang

    2018-01-01

    Micro ball tips with high precision, small diameter, and high stiffness stems are required to measure microstructures with high aspect ratio. Existing ball tips cannot meet such demands because of their weak qualities. This study used an arc-discharge melting method to fabricate a micro monolithic tungsten ball tip on a tungsten stylus. The principles of arc discharge and surface tension phenomenon were introduced. The experimental setup was designed and established. Appropriate process param...

  13. Radiologic characteristics of sinonasal fungus ball: an analysis of 119 cases

    International Nuclear Information System (INIS)

    Seo, Young-Joon; Kim, Kyubo; Kim, Jinna; Lee, Jeung-Gweon; Kim, Chang-Hoon; Yoon, Joo-Heon

    2011-01-01

    Background. It is important to differentiate sinonasal fungus ball from non-fungal sinusitis and other forms of fungal sinusitis in order to determine the optimal treatment. In particular, a sinonasal fungus ball, a non-invasive fungal sinusitis, can be characterized by radiologic findings before surgery. Purpose. To differentiate a sinonasal fungus ball from other types of sinusitis and determine optimal treatment on the basis of radiologic findings before surgery. Material and Methods. We studied 119 patients with clinically and pathologically proven sinonasal fungus balls. Their condition was evaluated radiologically with contrast-enhanced CT (99 patients), non-contrast CT (18 patients) and/or MRI (17 patients) prior to sinonasal surgery. Results. Calcifications were found in 78 of 116 (67.2%) patients who underwent CT scans for fungus ball. As opposed to non-contrast CT scans, contrast CT scans revealed hyper attenuating fungal ball in 82.8% and enhanced inflamed mucosa in 65.5% of the patients, respectively. On MRI, most sinonasal fungal balls showed iso- or hypointensity on T1-weighted images and marked hypointensity on T2-weighted images. Inflamed mucosal membranes were noted and appeared as hypointense on T1-weighted images (64.7%) and hyperintense on T2-weighted images (88.2%). Conclusion. When there are no calcifications visible on the CT scan, a hyper attenuating fungal ball located in the central area of the sinus with mucosal thickening on enhanced CT scans is an important feature of a non-invasive sinonasal fungus ball. On MRI, a sinonasal fungus ball has typical features of a marked hypointense fungus ball with a hyperintense mucosal membrane in T2-weighted images. A contrast-enhanced CT scan or MRI provides sufficient information for the preoperative differentiation of a sinonasal fungus ball from other forms of sinusitis

  14. The gym ball as a chair for the back pain patient: A two case report

    OpenAIRE

    Merritt, Larry G; Merritt, Celynne M

    2007-01-01

    The popularity of the gym ball has led to its increased use in programs designed for fitness, rehabilitation and prevention. Some people are using the gym ball to replace the office chair and others are sitting on it at home, which has created some controversy among therapists, researchers, ergonomics experts and the general public. The controversy is due in part to a lack of knowledge and experience with this application for the gym ball. Both patients in this report were suffering with low ...

  15. Dual PD Control Regulation with Nonlinear Compensation for a Ball and Plate System

    Directory of Open Access Journals (Sweden)

    Sergio Galvan-Colmenares

    2014-01-01

    Full Text Available The normal proportional derivative (PD control is modified to a new dual form for the regulation of a ball and plate system. First, to analyze this controller, a novel complete nonlinear model of the ball and plate system is obtained. Second, an asymptotic stable dual PD control with a nonlinear compensation is developed. Finally, the experimental results of ball and plate system are provided to verify the effectiveness of the proposed methodology.

  16. Computed tomography of ball pythons (Python regius) in curled recumbency.

    Science.gov (United States)

    Hedley, Joanna; Eatwell, Kevin; Schwarz, Tobias

    2014-01-01

    Anesthesia and tube restraint methods are often required for computed tomography (CT) of snakes due to their natural tendency to curl up. However, these restraint methods may cause animal stress. The aim of this study was to determine whether the CT appearance of the lungs differs for ball pythons in a curled position vs. tube restraint. Whole body CT was performed on ten clinically healthy ball pythons, first in curled and then in straight positions restrained in a tube. Curved multiplanar reformatted (MPR) lung images from curled position scans were compared with standard MPR lung images from straight position scans. Lung attenuation and thickness were measured at three locations for each scan. Time for positioning and scanning was 12 ± 5 min shorter for curled snakes compared to tube restraint. Lung parenchyma thickness and attenuation declined from cranial to caudal on both straight and curled position images. Mean lung parenchyma thickness was greater in curled images at locations 1 (P = 0.048) and 3 (P = 0.044). Mean lung parenchyma thickness decreased between location 1 and 2 by 86-87% (straight: curled) and between location 1 and 3 by 51-50% (straight: curled). Mean lung attenuation at location 1 was significantly greater on curled position images than tube restraint images (P = 0.043). Findings indicated that CT evaluation of the lungs is feasible for ball pythons positioned in curled recumbency if curved MPR is available. However, lung parenchyma thickness and attenuation in some locations may vary from those acquired using tube restraint. © 2014 American College of Veterinary Radiology.

  17. Development of a steel ball center alignment device based on Michelson interference concept.

    Science.gov (United States)

    Lee, Hau-Wei; Liu, Chien-Hung

    2014-09-01

    This study presents a ball center alignment method based on the Michelson interferometer where one of the reflecting mirrors is replaced by a lens and steel ball. By locating the ball away from the focal length of the lens, the beam is reflected as a spherical wave. The interference ring formed by the planar and spherical waves can be clearly observed using a camera without a lens. The distance of the offset of the ball center can be enhanced by more than 140% using this method. A fast ring profile fitting method can reduce circle fitting time to around a third of that needed for Hough transformation.

  18. Effects of Sprint Training With or Without Ball Carry in Elite Rugby Players.

    Science.gov (United States)

    Seitz, Laurent B; Barr, Matt; Haff, G Gregory

    2015-09-01

    To compare the effects of sprint training with or without ball carry on the sprint performance of elite rugby league players. Twenty-four elite rugby league players were divided into a ball-carry group (BC; n = 12) and a no-ball-carry group (NBC; n = 12). The players of the BC group were required to catch and carry the ball under 1 arm during each sprint, whereas the NBC group performed sprints without carrying a ball. The 8-wk training intervention took place during the precompetitive phase of the season and consisted of 2 sessions/wk. Sprint performance was measured before and after the training intervention with 40-m linear sprints performed under 2 conditions: with and without ball carry. Split times of 10, 20, and 40 m were recorded for further analysis. A 3-way (group × time × condition) factorial ANOVA was performed to compare changes in sprint performance with and without the ball, before and after the training intervention for both BC and NBC training groups Results: The BC and NBC groups experienced similar improvements in 10-, 20-, and 40-m sprint times and accelerations, regardless of the condition under which the sprint tests were performed (P = .19). Sprint training while carrying a rugby ball is as effective as sprint training without carrying a rugby ball for improving the sprint performance of elite rugby league players.

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

    Science.gov (United States)

    Higuchi, Takatoshi; Nagami, Tomoyuki; Nakata, Hiroki; Watanabe, Masakazu; Isaka, Tadao; Kanosue, Kazuyuki

    2016-01-01

    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 ball trajectory for improving hitting accuracy, which is likely due to visuo-motor delay.

  20. Training Level Does Not Affect Auditory Perception of The Magnitude of Ball Spin in Table Tennis.

    Science.gov (United States)

    Santos, Daniel P R; Barbosa, Roberto N; Vieira, Luiz H P; Santiago, Paulo R P; Zagatto, Alessandro M; Gomes, Matheus M

    2017-01-01

    Identifying the trajectory and spin of the ball with speed and accuracy is critical for good performance in table tennis. The aim of this study was to analyze the ability of table tennis players presenting different levels of training/experience to identify the magnitude of the ball spin from the sound produced when the racket hit the ball. Four types of "forehand" contact sounds were collected in the laboratory, defined as: Fast Spin (spinning ball forward at 140 r/s); Medium Spin (105 r/s); Slow Spin (84 r/s); and Flat Hit (less than 60 r/s). Thirty-four table tennis players of both sexes (24 men and 10 women) aged 18-40 years listened to the sounds and tried to identify the magnitude of the ball spin. The results revealed that in 50.9% of the cases the table tennis players were able to identify the ball spin and the observed number of correct answers (10.2) was significantly higher (χ 2 = 270.4, p ball spin. This indicates that auditory information contributes to identification of the magnitude of the ball spin, however, it also reveals that, in table tennis, the level of training does not interfere with the auditory perception of the ball spin.

  1. Comminution-amorphisation relationships during ball milling of lactose at different milling conditions.

    Science.gov (United States)

    Pazesh, Samaneh; Gråsjö, Johan; Berggren, Jonas; Alderborn, Göran

    2017-08-07

    The purpose of the study was to investigate the relationship between comminution and amorphisation of α-lactose monohydrate particles during ball milling under different milling conditions, including ball-to-powder mass ratio, milling time and ball diameter. The results revealed that at a constant ball filling ratio, ball-to-powder mass ratio of 25:1 resulted in the lowest minimum particle diameter of ∼5μm and the highest degree of apparent amorphous content of 82%. The rate of comminution was high during early stage of milling whereas the degree of apparent amorphous content increased gradually at a slow rate. An increased ball-to-powder mass ratio during milling increased both the rate of comminution and the rate of amorphisation. Using a given ball-to-powder mass ratio, the ball diameter affected the degree of apparent amorphous content of the particles while the particle diameter remained unchanged. The relationship between comminution and amorphisation could be described as consisting of two stages, i.e. comminution dominated and amorphisation dominated stage. It was proposed that the rate constant of comminution and amorphisation are controlled by stress energy distribution in the milling jar and the stress energy distribution is regulated by the ball motion pattern that can be affected by the process parameter used. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  2. IceCube potential for detecting Q-ball dark matter in gauge mediation

    International Nuclear Information System (INIS)

    Kasuya, Shinta; Kawasaki, Masahiro; Yanagida, Tsutomu T.

    2015-01-01

    We study Q-ball dark matter in gauge-mediated supersymmetry breaking, and seek the possibility of detection in the IceCube experiment. We find that the Q balls would be the dark matter in the parameter region different from that for gravitino dark matter. In particular, the Q ball is a good dark matter candidate for low reheating temperature, which may be suitable for the Affleck–Dine baryogenesis and/or nonthermal leptogenesis. Dark matter Q balls are detectable by IceCube-like experiments in the future, which is a peculiar feature compared to the case of gravitino dark matter

  3. Motion of a Probe Ball in the Fluid under Centrifugal Acceleration

    OpenAIRE

    Nyrkova , I.; Semenov , A.; Khokhlov , A.; Linliu , K.; Chu , B.

    1997-01-01

    The viscosity of a fluid can be measured by observing the motion of a probe sphere (or ball) in a centrifuge tube filled with this fluid. The hydrodynamic behavior of the probe ball moving in the centrifuge tube has been solved theoretically. We have got the universal relationship (for balls of a given material and size in a given tube) between the terminal ball velocity, the fluid viscosity and the centrifuge acceleration using the only adjustable parameter — the rotational friction coeffici...

  4. 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.

  5. 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.

  6. Statics and dynamics of a self-bound matter-wave quantum ball

    Science.gov (United States)

    Adhikari, S. K.

    2017-02-01

    We study the statics and dynamics of a stable, mobile, three-dimensional matter-wave spherical quantum ball created in the presence of an attractive two-body and a very small repulsive three-body interaction. The quantum ball can propagate with a constant velocity in any direction in free space and its stability under a small perturbation is established numerically and variationally. In frontal head-on and angular collisions at large velocities two quantum balls behave like quantum solitons. Such collision is found to be quasielastic and the quantum balls emerge after collision without any change of direction of motion and velocity and with practically no deformation in shape. When reflected by a hard impenetrable plane, the quantum ball bounces off like a wave obeying the law of reflection without any change of shape or speed. However, in a collision at small velocities two quantum balls coalesce to form a larger ball which we call a quantum-ball breather. We point out the similarity and difference between the collision of two quantum and classical balls. The present study is based on an analytic variational approximation and a full numerical solution of the mean-field Gross-Pitaevskii equation using the parameters of 7Li atoms.

  7. Tuned rolling-ball dampers for vibration control in wind turbines

    DEFF Research Database (Denmark)

    Chen, Junling; Georgakis, Christos T.

    2013-01-01

    -ball damper characterized by single or multiple steel balls rolling in a spherical container is proposed to be mounted on the top of wind turbines to reduce the wind-induced vibration. A 1/20 scale shaking table model was developed to evaluate the control effectiveness of the damper. The wind-induced dynamic...... that with only one ball because of the impact effect and the rolling friction. The control effectiveness of the damper cannot be improved further when the number of balls is increased beyond a certain point....

  8. 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)

  9. 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.

  10. Identification of sources of tar balls deposited along the Goa coast, India, using fingerprinting techniques

    International Nuclear Information System (INIS)

    Suneel, V.; Vethamony, P.; Zakaria, M.P.; Naik, B.G.; Prasad, K.V.S.R.

    2013-01-01

    Highlights: ► This is first fingerprinting study in India on identification of source of tar balls. ► Tar balls were formed from tanker-wash spills and they resemble floating tar ball. ► δ 13 C values of Bombay High crude oil and the present tar balls do not match. ► Compound specific stable carbon isotope analysis confirmed the source of tar balls. ► Source is confirmed as the South East Asian Crude Oil and not the Bombay High crude. -- Abstract: Deposition of tar balls along the coast of Goa, India is a common phenomenon during the southwest monsoon. Representative tar ball samples collected from various beaches of Goa and one Bombay High (BH) crude oil sample were subjected to fingerprint analysis based on diagnostic ratios of n-alkane, biomarkers of pentacyclic tri-terpanes and compound specific stable carbon isotope (δ 13 C) analysis to confirm the source. The results were compared with the published data of Middle East Crude Oil (MECO) and South East Asian Crude Oil (SEACO). The results revealed that the tar balls were from tanker-wash derived spills. The study also confirmed that the source is not the BH, but SEACO. The present study suggests that the biomarkers of alkanes and hopanes coupled with stable carbon isotope analysis act as a powerful tool for tracing the source of tar balls, particularly when the source specific biomarkers fail to distinguish the source

  11. Sports injuries in adolescents' ball games: soccer, handball and basketball.

    OpenAIRE

    Yde, J; Nielsen, A B

    1990-01-01

    In a prospective study of 302 adolescent players in three ball games (soccer, handball and basketball), 119 incurred injuries. The injury incidence (number of injuries per 1000 playing hours) was 5.6 in soccer, 4.1 in handball and 3.0 in basketball. Ankle sprains accounted for 25 per cent of the injuries, finger sprains 32 per cent, strains in the thigh and leg 10 per cent, and tendinitis/apophysitis 12 per cent. The most serious injuries were four fractures, one anterior cruciate ligament ru...

  12. Formation of ball-milled Fe-Mo nanostructured powders

    Energy Technology Data Exchange (ETDEWEB)

    Moumeni, H. [Laboratoire de Magnetisme et de Spectroscopie des Solides, LM2S, Departement de Physique, Faculte des Sciences, Universite de Annaba, B.P. 12, 23000 Annaba-Algerie (Algeria) and Departement de Physique, Faculte des Sciences et de l' Ingenierie, Universite de Guelma, B.P. 401, 24000 Guelma-Algerie (Algeria)]. E-mail: hmoumeni@yahoo.fr; Alleg, S. [Laboratoire de Magnetisme et de Spectroscopie des Solides, LM2S, Departement de Physique, Faculte des Sciences, Universite de Annaba, B.P. 12, 23000 Annaba-Algerie (Algeria); Greneche, J.M. [Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087, Universite du Maine, Faculte des Sciences, F-72085, Le Mans Cedex 9 (France)

    2006-08-10

    Nanostructured Fe-6 wt.%Mo powders were prepared by mechanical alloying in a high-energy planetary ball-mill. The structural changes and the kinetics of Mo dissolution were studied by using X-ray diffraction. The crystallite size reduction down to about 11 nm is accompanied by the introduction of internal strains up to 1.1% (root-mean square strain, rms). After 24 h of milling, a bcc Fe(Mo) solid solution is formed. The kinetics of Mo dissolution into the Fe matrix during the milling process can be described by two regimes characterized by small values of Avrami parameter which do not exceed unit.

  13. Casimir entropy for a ball in front of a plane

    Science.gov (United States)

    Bordag, M.; Pirozhenko, I. G.

    2010-12-01

    The violation of the third law of thermodynamics for metals described by the Drude model and for dielectrics with finite dc conductivity is one of the most interesting problems in the field of the Casimir effect. It manifests itself as a nonvanishing of the entropy for vanishing temperature. We review the relevant calculations for plane surfaces and calculate the corresponding contributions for a ball in front of a plane. In this geometry, these appear in much the same way as for parallel planes. We conclude that the violation of the 3rd law is not related to the infinite size of the planes.

  14. Analysis of the ball-plate laser fusion target experiments

    International Nuclear Information System (INIS)

    Pan, Y.L.

    1975-01-01

    Two dimensional computer simulation results of the two exploding pusher ball-plate targets are in approximate agreement with the experimental space and time integrated x-ray spectra, x-ray microscope data, neutron yields, and laser energy absorptions. Three parameters were used to characterize the laser absorption due to plasma instabilities. Two dumpall parameters were used to model the energy absorption and a single variable was used to define the electron temperature. The values, as well as the selection procedure for these parameters are discussed

  15. Tungsten-nanodiamond composite powders produced by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, D., E-mail: daniela.nunes@ist.utl.pt [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); ICEMS, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Livramento, V. [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); Mardolcar, U.V. [Departamento de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Centro de Ciencias Moleculares e Materiais, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Correia, J.B. [LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); Carvalho, P.A. [ICEMS, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Departamento de Bioengenharia, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2012-07-15

    The major challenge in producing tungsten-nanodiamond composites by ball milling lies in successfully dispersing carbon nanoparticles in the metallic matrix while keeping carbide formation at a minimum. Processing windows for carbide minimization have been established through systematic variation of the nanodiamond fraction, milling energy and milling time. Materials characterization has been carried out by X-ray diffraction, scanning and transmission electron microscopy and microhardness testing. Nanostructured matrices with homogeneously dispersed particles that preserved the diamond structure have been produced. Differential thermal analysis has been used to evaluate the composites thermal stability.

  16. On the origin of the drag force on golf balls

    Science.gov (United States)

    Balaras, Elias; Beratlis, Nikolaos; Squires, Kyle

    2017-11-01

    It is well establised that dimples accelerate the drag-crisis on a sphere. The result of the early drag-crisis is a reduction of the drag coefficient by more than a factor of two when compared to a smooth sphere at the same Reynolds number. However, when the drag coefficients for smooth and dimpled spheres in the supercritical regime are compared, the latter is higher by a factor of two to three. To understand the origin of this behavior we conducted direct numerical simulations of the flow around a dimpled sphere, which is similar to commercially available golf balls, in the supercritical regime. By comparing the results to those for a smooth sphere it is found that dimples, although effective in accelerating the drag crisis, impose a local drag-penalty, which contributes significantly to the overall drag force. This finding challenges the broadly accepted view, that the dimples only indirectly affect the drag force on a golf ball by manipulating the structure of the turbulent boundary layer near the wall and consequently affect global separation. Within this view, typically the penalty on the drag force imposed by the dimples is assumed to be small and coming primarily from skin friction. The direct numerical simulations we will report reveal a very different picture.

  17. Ball-grid array architecture for microfabricated ion traps

    Science.gov (United States)

    Guise, Nicholas D.; Fallek, Spencer D.; Stevens, Kelly E.; Brown, K. R.; Volin, Curtis; Harter, Alexa W.; Amini, Jason M.; Higashi, Robert E.; Lu, Son Thai; Chanhvongsak, Helen M.; Nguyen, Thi A.; Marcus, Matthew S.; Ohnstein, Thomas R.; Youngner, Daniel W.

    2015-05-01

    State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensive surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with 40Ca+ ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with 171Yb+ ions in a second BGA trap.

  18. Ball-grid array architecture for microfabricated ion traps

    International Nuclear Information System (INIS)

    Guise, Nicholas D.; Fallek, Spencer D.; Stevens, Kelly E.; Brown, K. R.; Volin, Curtis; Harter, Alexa W.; Amini, Jason M.; Higashi, Robert E.; Lu, Son Thai; Chanhvongsak, Helen M.; Nguyen, Thi A.; Marcus, Matthew S.; Ohnstein, Thomas R.; Youngner, Daniel W.

    2015-01-01

    State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensive surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with 40 Ca + ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with 171 Yb + ions in a second BGA trap

  19. MODELLING OF HEAT CONDUCTIVITY OF COMPOSITE MATERIALS WITH BALL INCLUSIONS

    Directory of Open Access Journals (Sweden)

    V. Pugachev Oleg

    2017-01-01

    Full Text Available A number of papers deals with the heat conductivity of composite materials: Zarubin et al used new approaches to the problem of evaluation of the effective heat conductivity coefficients of composite material with ball inclusions. We used variational analysis for a simplified model in a vicinity of inclusion. Contemporary computers allow implementing another approach to solving the problem of the effective heat conductivity: it may be modelled by the Brownian motion of virtual heat particles. The main idea is to obtain the exact formula for the heat conductivity for a homogeneous material and subsequently obtain a statistical evaluation of this formula for a composite material.In the present paper we compare two methods for finding the effective heat conductivity coefficients of composite materials by modeling the process of heat conduction via the Brownian motion of virtual heat particles. We consider a composite with ball inclusions of a material with heat conductivity and heat capacity coefficientsdiffering from those of the matrix material. In a computational experiment, we simulate the process of heatconduction through a flat layer of the composite material, which has been heated on one side at the initial moment. In order to find the confidence interval for the effective heat conductivity coefficient, we find, by means of statistics, either the displacement of the center of heat energy, or the probability of a virtual particle to pass through the layer during a certain time. We compare our results with theoretical assessments suggested by other authors.

  20. Finite element modelling of the dynamics of groovy ball bearings

    Directory of Open Access Journals (Sweden)

    Ajala Olamide

    2018-01-01

    Full Text Available Geometry modified thrust bearings exposed to rolling and sliding contact are subjected to wear and localized frictional heating caused by relative slip between the two sliding surfaces. This leads to a rise in temperature, thermal stresses and changes in the elastic and plastic strength and physical properties of the material. The changes in the properties in turn alter the stress state, the displacement field, life and reliability of the bearing. Hence, a finite-element model is created to study the dynamics of groovy thrust bearing. In this paper, Hertz contact theory and numerical method are used to simulate the dynamics and kinematics of groovy ball bearings. The optimal loading parameters are identified in this study based on the analysis of the system responses and properties. The results of the numerical analysis and validation are presented. The numerical analysis proves the concept of transforming rotational motion into axial oscillation and demonstrates the capabilities of the numerical simulation to accurately model the dynamics of the groovy ball bearing.

  1. Rheological characterization of nuclear waste using falling-ball rheometry

    International Nuclear Information System (INIS)

    Abbott, J.R.; Unal, C.; Stephens, T.; Pasamehmetoglu, K.O.; Graham, A.L.; Edwards, J.N.

    1994-01-01

    Knowledge of the rheological properties of saturated solutions containing solid particles is very important in nuclear waste management technology. For example, the nuclear waste in the Hanford Site high-level radioactive waste tanks contains strong electrolyte solutions with a high concentration of solids. Previous attempt using rotational viscometers to determine the rheology has shown unusual thixotropic and shear thinning behaviors with a lack of reproducibility. Using falling-ball rheometry, the rheology of the undisturbed simulant may be determined with much better reproducibility. In this study, a well-mixed simulant which has similar chemical composition to the actual waste will be tested. Falling-ball size and density will be varied to get data in a wide range of shear rates. To determine the rheogram, several methods will be tried to match the observed data. Based on these tests, a rheogram can be determined from the model and its best-fit parameters. The simulant shows shear-thinning behavior and a yield stress. This would suggest a H-B model. But when fitting to one of the simulants which showed a very low yield stress, the predictions assuming no yield and assuming yield resulted in no improvement in the fit when assuming yield

  2. Lubrication of an 85-mm ball bearing with RP-1

    Science.gov (United States)

    Addy, Harold E., Jr.; Schuller, Fredrick T.

    1993-01-01

    A parametric experimental investigation of an 85 millimeter bore angular contact ball bearing running in RP-1 fuel was performed at speeds of 10,000 to 24,000 rpm. Thrust loads were varied from 4450 to 17,800 Newtons (1000 to 4000 lbs.). Radial loads were varied from 1335 to 13,350 Newtons (300 to 3000 lbs.). RP-1 lubrication for the bearing was provided through a stationary jet ring located adjacent to the test bearing outer ring. Increases in both the thrust and radial loads resulted in increased bearing temperature, while increases in shaft speed resulted in much more dramatic increases in bearing temperature. These trends are typical for ball bearings operating under these types of conditions. Results are given for outer ring temperatures of the test bearing at the various test conditions employed. In addition, the heat energy removed from the bearing by the RP-1 was determined by measuring the increase in temperature as the RP-1 passed through the bearing. Results showed that the amount of heat energy removed by the RP-1 increased with both shaft speed and RP-1 flow rate to the bearing.

  3. Critical flaw size in silicon nitride ball bearings

    Science.gov (United States)

    Levesque, George Arthur

    Aircraft engine and bearing manufacturers have been aggressively pursuing advanced materials technology systems solutions to meet main shaft-bearing needs of advanced military aircraft engines. Ceramic silicon nitride hybrid bearings are being developed for such high performance applications. Though silicon nitride exhibits many favorable properties such as high compressive strength, high hardness, a third of the density of steel, low coefficient of thermal expansion, and high corrosion and temperature resistance, they also have low fracture toughness and are susceptible to failure from fatigue spalls emanating from pre-existing surface flaws that can grow under rolling contact fatigue (RCF). Rolling elements and raceways are among the most demanding components in aircraft engines due to a combination of high cyclic contact stresses, long expected component lifetimes, corrosive environment, and the high consequence of fatigue failure. The cost of these rolling elements increases exponentially with the decrease in allowable flaw size for service applications. Hence the range of 3D non-planar surface flaw geometries subject to RCF is simulated to determine the critical flaw size (CFS) or the largest allowable flaw that does not grow under service conditions. This dissertation is a numerical and experimental investigation of surface flaws in ceramic balls subjected to RCF and has resulted in the following analyses: Crack Shape Determination: the nucleation of surface flaws from ball impact that occurs during the manufacturing process is simulated. By examining the subsurface Hertzian stresses between contacting spheres, their applicability to predicting and characterizing crack size and shape is established. It is demonstrated that a wide range of cone and partial cone cracks, observed in practice, can be generated using the proposed approaches. RCF Simulation: the procedure and concerns in modeling nonplanar 3D cracks subject to RCF using FEA for stress intensity

  4. Further reply to remarks of R Cross on ‘A comparative study of two types of ball-on-ball collision’

    Science.gov (United States)

    White, Colin

    2018-03-01

    In this letter, I show how a perceived approximation error in my first letter, White (2017 Phys. Ed. 53 016502) concerning my explanation of the dynamic motion of two interacting Newtons Cradle balls, proves to me insignificant. Although these second and third order errors described are shown to be minimal, they do raise the opportunity to discuss the precise and more intricate ball interactions in finer detail.

  5. Bringing the Community to Campus: An Oral History of Women's Week at Ball State University

    Science.gov (United States)

    Jarrett, Courtney

    2012-01-01

    This dissertation examined the annual Women's Week events hosted by Ball State's Women's and Gender Studies Program. It served to paint a historical picture of how the local Muncie community has been linked with the academic community at Ball State through events about women's issues. The program began when a group of people wanting to broaden the…

  6. The small displacement elastic solution to the ball-on-ring testing method

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund

    2012-01-01

    The ball-on-ring experiment is used for testing of the biaxial strength of ceramics. In this work the solution for the stress distribution and displacements of the disc specimen in the ball-on-ring experiment are determined on closed form. The solution comprises the displacement field and its...

  7. Randomized Controlled Trial of Use of the Peanut Ball During Labor.

    Science.gov (United States)

    Roth, Cheryl; Dent, Sarah A; Parfitt, Sheryl E; Hering, Sandra L; Bay, R Curtis

    2016-01-01

    The purpose of this study was to evaluate the efficacy of peanut ball use on duration of first stage labor and pushing time in women who were scheduled for elective induction of labor at ≥39 weeks gestation and planning an epidural. In this randomized controlled trial, women having labor induction and planning a labor epidural were assigned (1:1) to one of two groups: one group used a peanut ball and one group did not. Outcome variables were time spent in first stage labor and time spent pushing. Factors included group assignment (peanut ball, no peanut ball), parity (primiparous, multiparous), and race. Age and maximum oxytocin dose served as covariates. Among women having elective induction with epidural analgesia, use of a peanut ball reduced first stage labor duration for primiparous patients significantly more than multiparous patients, p = 0.018. There was no significant difference in the reduction of length of first stage labor for multiparous women, p = 0.057 with use of the peanut ball. Peanut ball use did not alter length of pushing time for either group, p > 0.05. Use of peanut balls may reduce total labor time to a greater degree in primiparous patients than multiparous patients having elective induction at ≥39 weeks with epidural analgesia.

  8. Method and apparatus for jetting, manufacturing and attaching uniform solder balls

    Science.gov (United States)

    Yost, F.G.; Frear, D.R.; Schmale, D.T.

    1999-01-05

    An apparatus and process are disclosed for jetting molten solder in the form of balls directly onto all the metallized interconnects lands for a ball grid array package in one step with no solder paste required. Molten solder is jetted out of a grid of holes using a piston attached to a piezoelectric crystal. When voltage is applied to the crystal it expands forcing the piston to extrude a desired volume of solder through holes in the aperture plate. When the voltage is decreased the piston reverses motion creating an instability in the molten solder at the aperture plate surface and thereby forming spherical solder balls that fall onto a metallized substrate. The molten solder balls land on the substrate and form a metallurgical bond with the metallized lands. The size of the solder balls is determined by a combination of the size of the holes in the aperture plate, the duration of the piston pulse, and the displacement of the piston. The layout of the balls is dictated by the location of the hooks in the grid. Changes in ball size and layout can be easily accomplished by changing the grid plate. This invention also allows simple preparation of uniform balls for subsequent supply to BGA users. 7 figs.

  9. 75 FR 38019 - Safety Zone; Fixed Mooring Balls, South of Barbers Pt. Harbor Channel, Oahu, HI

    Science.gov (United States)

    2010-07-01

    ... DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 165 [Docket No. USCG-2010-0457] RIN 1625-AA00 Safety Zone; Fixed Mooring Balls, South of Barbers Pt. Harbor Channel, Oahu, HI AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: Due to the placement of six fixed mooring balls in an...

  10. Social Media and Big Data – Cracks in the Crystal Ball?

    NARCIS (Netherlands)

    Westera, Wim

    2013-01-01

    Westera, W. (2013, 14 October). Social Media and Big Data – Cracks in the Crystal Ball? Invited e-paper at ESOMAR RW Connect. http://rwconnect.esomar.org/using-social-media-for-market-analysis-cracks-in-the-alleged-crystal-ball/

  11. 48 CFR 252.225-7016 - Restriction on acquisition of ball and roller bearings.

    Science.gov (United States)

    2010-10-01

    ... of ball and roller bearings. 252.225-7016 Section 252.225-7016 Federal Acquisition Regulations System... and roller bearings. As prescribed in 225.7009-5, use the following clause: Restriction on Acquisition of Ball and Roller Bearings (MAR 2006) (a) Definitions. As used in this clause' (1) Bearing...

  12. 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.

  13. Wiffle Ball: Turning a Backyard Favorite into an Appropriate Physical Education Unit

    Science.gov (United States)

    Layne, Todd E.

    2017-01-01

    Wiffle ball is a game that has been played for many years (Santora, 2003). Unfortunately, implementation in physical education has been inconsistent at best. The sport education model outlined in this article provides an appropriate method for teaching skills associated with wiffle ball for a variety of ages. Students can develop appropriate…

  14. Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection.

    Science.gov (United States)

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

    2017-12-05

    Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball's outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified.

  15. Ball flight kinematics, release variability and in-season performance in elite baseball pitching.

    Science.gov (United States)

    Whiteside, D; McGinnis, R S; Deneweth, J M; Zernicke, R F; Goulet, G C

    2016-03-01

    The purpose of this study was to quantify ball flight kinematics (ball speed, spin rate, spin axis orientation, seam orientation) and release location variability in the four most common pitch types in baseball and relate them to in-season pitching performance. Nine NCAA Division I pitchers threw four pitching variations (fastball, changeup, curveball, and slider) while a radar gun measured ball speed and a 600-Hz video camera recorded the ball trajectory. Marks on the ball were digitized to measure ball flight kinematics and release location. Ball speed was highest in the fastball, though spin rate was similar in the fastball and breaking pitches. Two distinct spin axis orientations were noted: one characterizing the fastball and changeup, and another, the curveball and slider. The horizontal release location was significantly more variable than the vertical release location. In-season pitching success was not correlated to any of the measured variables. These findings are instructive for inferring appropriate hand mechanics and spin types in each of the four pitches. Coaches should also be aware that ball flight kinematics might not directly relate to pitching success at the collegiate level. Therefore, talent identification and pitching evaluations should encompass other (e.g., cognitive, psychological, and physiological) factors. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Clinical outcomes of ceramicized ball heads in total hip replacement bearings: a literature review.

    Science.gov (United States)

    Piconi, Corrado; De Santis, Vincenzo; Maccauro, Giulio

    2017-01-26

    Metallic ball heads for total hip replacement (THR) bearings with ceramicized surfaces were introduced in orthopedics during the second half of the 1980s, with the aim of decreasing the wear of polyethylene cups. An analysis was made of the literature regarding outcomes for metallic ball heads with ceramicized surfaces now in clinical use (TiN, TiNbN, ZrN, monoclinic ZrO2), as well as carbon coatings (pyrolytic carbon, diamond-like carbon) and silicon nitride as coatings in ball heads for THR bearings. Notwithstanding the diffusion of ceramicized ball heads in THRs, there are few reports about their clinical outcomes in hip arthroplasty. In addition, several clinical studies and some registry data are putting under scrutiny the clinical advantages of ceramicized ball heads over cobalt chrome (CoCr) alloy and ceramic ball heads. The wear of THR bearings with ceramicized ball heads looks like it depends more on the behavior of the polyethylene cups than on the treatment of the ball head surface. The risk of coating damage and of its consequences has to be taken into account in selecting this type of bearing.

  17. Maxillary sinus volume: new physiopathological data in fungal ball genesis? A retrospective study.

    Science.gov (United States)

    Michel, J; Radulesco, T; Mancini, J; Paganelli, A; Varoquaux, A; Adalian, P; Ranque, S; Dessi, P

    2017-08-01

    The goal of this study was to compare maxillary sinus (MS) volume in patients with, or without, maxillary fungal ball. Monocentric retrospective study performed on 115 patient CT scans. We defined two groups of patients according to the absence (control group) or the presence (fungal ball group) of unilateral fungal ball in the MS. Sinus 3D reconstruction was created from CT scan. Control group: 71 patients (36 women - 50.7%); mean age was 51 years. Fungal ball group: 44 patients (29 women - 65.9%); mean age was 54.5 years. The univariate association between MS volume and sinus covariates was tested by anova. Multivariate analysis was made including all variables statistically significant in univariate analysis. In the control group, mean MS volume was 14 766 mm 3 . The volumes of the two MSs were not statistically different in the control group (P = 0.145). In the fungal ball group, mean MS volume was 15 982 mm 3 . Fungal ball was found in the smallest MS in 41 of 44 cases. Univariate analysis showed a statistical difference between the pathological and the non-pathological MS volumes (P ball (P ball is associated with a smaller size of the affected MS. © 2017 John Wiley & Sons Ltd.

  18. Contributions of Stephen J. Ball to the Research on Educational and Curriculum Policies in Brazil

    Science.gov (United States)

    Mainardes, Jefferson; Gandin, Luis Armando

    2013-01-01

    This article aims at showcasing the main contributions of Stephen J. Ball to educational research in Brazil, particularly to the study of educational and curriculum policies. We also highlight some of the limitations in the incorporation of Ball's ideas in Brazil as well as some of the challenges that these author's ideas pose to Brazilian…

  19. Illustrating the Basic Functioning of Mass Analyzers in Mass Spectrometers with Ball-Rolling Mechanisms

    Science.gov (United States)

    Horikoshi, Ryo; Takeiri, Fumitaka; Mikita, Riho; Kobayashi, Yoji; Kageyama, Hiroshi

    2017-01-01

    A unique demonstration with ball-rolling mechanisms has been developed to illustrate the basic principles of mass analyzers as components of mass spectrometers. Three ball-rolling mechanisms mimicking the currently used mass analyzers (i.e., a quadrupole mass filter, a magnetic sector, and a time-of- flight) have been constructed. Each mechanism…

  20. Sport-Based Youth and Community Development: Beyond the Ball in Chicago

    Science.gov (United States)

    Jacobs, Jennifer M.; Castañeda, Amy; Castañeda, Rob

    2016-01-01

    Rob and Amy Castañeda, the co-founders of a sports/play-based youth and community development organization called Beyond the Ball (www.beyondtheball.org), cite the collaborative and dynamic nature of the TPSR Alliance as an important influence for their work. Beyond the Ball serves individuals between kindergarten and post-college, in the North…

  1. On Not Researching School Leadership: The Contribution of S. J. Ball

    Science.gov (United States)

    Gunter, Helen M.

    2013-01-01

    Stephen Ball's research continues to make a contribution to describing, understanding and explaining the political, social, economic and cultural context in which educational professionals locate their practices. Therefore, Ball engages with issues about school leadership, but he does not set out to present solutions for school leaders. Based…

  2. Simulating Army-Relevant Spur Gear Contacts with a Ball-on-Disc Tribometer

    Science.gov (United States)

    2015-09-01

    ARL-TR-7492 ● SEP 2015 US Army Research Laboratory Simulating Army-Relevant Spur Gear Contacts with a Ball -on-Disc Tribometer...Research Laboratory Simulating Army-Relevant Spur Gear Contacts with a Ball -on-Disc Tribometer by Mark R Riggs, Stephen P Berkebile, Adrian A...

  3. Impact Velocity and Coefficient of Restitution for a Tennis Ball Impacting a Tennis Racquet

    Directory of Open Access Journals (Sweden)

    Mongkol Sukpraprut

    2015-01-01

    Full Text Available The impact and exit velocities of a tennis ball impacting on a fixed tennis racquet were measured with high speed video analysis to determine the coefficient of restitution (COR. It was found that there is a negative linear relationship between the COR and the impact velocity of the ball for velocities between 13 and 36 m/s.

  4. Determining the Viscosity of Liquids Using an Extended Falling Ball Method

    Science.gov (United States)

    Houari, Ahmed

    2011-01-01

    In this article, I will extend the falling ball method to measure the viscosity of liquids regardless of the degree of their viscosity. For this, I will show that one can obtain a measurement of the terminal velocity of a falling spherical ball in a viscous liquid by solving numerically the equation of motion which describes the dynamics of the…

  5. 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 ...

  6. Collision of a Ball with a Barbell and Related Impulse Problems

    Science.gov (United States)

    Mungan, Carl E.

    2007-01-01

    The collision of a ball with the end of a barbell illustrates the combined conservation laws of linear and angular momentum. This paper considers the instructive but unfamiliar case where the ball's incident direction of travel makes an acute angle with the barbell's connecting rod. The analysis uses the coefficient of restitution generalized to…

  7. Space Shuttle Orbital Maneuvering Subsystem (OMS) Engine Propellant Leakage Ball-Valve Shaft Seals

    Science.gov (United States)

    Lueders, Kathy; Buntain, Nick; Fries, Joseph (Technical Monitor)

    1999-01-01

    Evidence of propellant leakage across ball-valve shaft seals has been noted during the disassembly of five flight engines and one test engine at the NASA Lyndon B. Johnson Space Center, White Sands Test Facility. Based on data collected during the disassembly of these five engines, the consequences of propellant leakage across the ball-valve shaft seals can be divided into four primary areas of concern: Damage to the ball-valve pinion shafts, damage to sleeved bearings inside the ball-valve and actuator assemblies, degradation of the synthetic rubber o-rings used in the actuator assemblies, and corrosion and degradation to the interior of the actuator assemblies. The exact time at which leakage across the ball-valve shaft seals occurs has not been determined, however, the leakage most likely occurs during engine firings when, depending on the specification used, ball-valve cavity pressures range as high as 453 to 550 psia. This potential pressure range for the ball-valve cavities greatly exceeds the acceptance leakage test pressure of 332 psia. Since redesign and replacement of the ball-valve shaft seals is unlikely, the near term solution to prevent damage that occurs from shaft-seal leakage is to implement a routine overhaul and maintenance program for engines in the fleet. Recommended repair, verification, and possible preventative maintenance measures are discussed in the paper.

  8. Simulation of Trajectories of Tar Ball Transport to the Goa Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Suneel, V.; Vethamony, P.; VinodKumar, K.; Babu, M.T.; Prasad, V.S.R.

    reasonably well with the observations. The present study confirms our view that the source of these tar balls is the accidental spills or tanker-wash along the international oil tanker route in the AS. A review of the global scenario of tar ball study is also...

  9. Parched elasto hydrodynamic lubrication film thickness measurement in an instrument ball bearing

    Science.gov (United States)

    Kingsbury, E.; Schritz, B.; Prahl, J.

    1988-01-01

    Parched Elasto Hydrodynamic Lubricant (PEHL) film thickness in a large instrument ball bearing is measured by electrical capacitance across its ball set. Correlation is shown between changes in film thickness and changes in Basic Speed Ratio (BSR) measured at the same time. BSR is confirmed as a sensitive, non-intrusive measure of transients in film thickness in a real bearing.

  10. Ammonia synthesis over multi-promoted iron catalysts obtained by high-energy ball-milling

    DEFF Research Database (Denmark)

    Jacobsen, C.J.H.; Jiang, Jianzhong; Mørup, Steen

    1999-01-01

    The feasibility of producing ammonia synthesis catalysts from high-energy ball-milling of a simple mixture of the constituent oxides has been investigated. The effect of ball-milling the fused oxidic precursor of the industrial KM1 ammonia synthesis catalyst has also been studied. The results show...

  11. 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.

  12. Survival of Phytophthora ramorum in Rhododendron root balls and in rootless substrates

    Science.gov (United States)

    A. Vercauteren; M. Riedel; M. Maes; S. Werres; K. Heungens

    2013-01-01

    This study assesses the survival of Phytophthora ramorum in the root ball of Rhododendron container plants as well as in different rootless forest substrates and a horticultural potting medium. Following inoculation of the root balls, the aboveground plant parts stayed symptomless, whilst the pathogen could be recovered with a...

  13. Simulation for grinding balls production using sand mold-gravity casting

    Science.gov (United States)

    Nurjaman, F.; Shofi, A.; Herlina, U.; Prilitasari, N. M.; Triapriani, Y.

    2018-01-01

    In this present work, the grinding balls from high chromium white cast iron (ASTM A-532) were produced by using sand mold-gravity casting. The simulation casting process was conducted before making these grinding balls by using SOLIDCast™ version 8.2.0. The gating system design and the pouring temperature of hot metal were investigated clearly to obtain grinding balls with no-defect. The sound casting of grinding balls was resulted by using the proper gating system with the addition of vent air on the top of each grinding ball’s mold. The dimension of vent air was reduced by the increasing of pouring temperature, thus it resulted on the increasing of the yield production of grinding balls.

  14. Regularity and mechanism of wheat straw properties change in ball milling process at cellular scale.

    Science.gov (United States)

    Gao, Chongfeng; Xiao, Weihua; Ji, Guanya; Zhang, Yang; Cao, Yaoyao; Han, Lujia

    2017-10-01

    To investigate the change of structure and physicochemical properties of wheat straw in ball milling process at cellular scale, a series of wheat straws samples with different milling time were produced using an ultrafine vibration ball mill. A multitechnique approach was used to analyze the variation of wheat straw properties. The results showed that the characteristics of wheat straw powder displayed regular changes as a function of the milling time, i.e., the powder underwent the inversion of breakage to agglomerative regime during wheat straw ball milling process. The crystallinity index, bulk density and water retention capacity of wheat straw were exponential relation with ball milling time. Moreover, ball milling continually converted macromolecules of wheat straw cell wall into water-soluble substances resulting in the water extractives proportional to milling time. Copyright © 2017. Published by Elsevier Ltd.

  15. 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.

  16. Numerical simulation of bearing balls in the plasma immersion ion implantation process

    International Nuclear Information System (INIS)

    Yu Yonghao; Wang Langping; Wang Xiaofeng; Tang Baoyin; Gan Kongyin; Liu Hongxi; Wang Yuhang; Wang Songyan

    2004-01-01

    The process of bearing balls in the plasma immersion ion implantation (PIII) was simulated using a 2-dimensional particle-in-cell (PIC) model. The distributions of normalized potential and dose were studied. In order to avoid overlap of sheaths between different balls in batch process, the minimum distance between two neighboring balls was calculated. When the voltage is -40 kV, plasma density is 4.8 x 10 9 cm -3 and pulse width is 10 μs, the minimum distance between two balls should be 34.18 cm. In addition, the dose distribution along the circumference of the ball is non-uniform. Consequently, a revolving substrate was used to improve the uniformity. Furthermore, to evaluate the model, the expansion process of sheath was measured using a Langmuir probe. Experimental results agree with the calculated value, and the maximum relative error is less than 8.4%. (authors)

  17. 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.

  18. 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.

  19. Development of a table tennis robot for ball interception using visual feedback

    Science.gov (United States)

    Parnichkun, Manukid; Thalagoda, Janitha A.

    2016-07-01

    This paper presents a concept of intercepting a moving table tennis ball using a robot. The robot has four degrees of freedom(DOF) which are simplified in such a way that The system is able to perform the task within the bounded limit. It employs computer vision to localize the ball. For ball identification, Colour Based Threshold Segmentation(CBTS) and Background Subtraction(BS) methodologies are used. Coordinate Transformation(CT) is employed to transform the data, which is taken based on camera coordinate frame to the general coordinate frame. The sensory system consisted of two HD Web Cameras. The computation time of image processing from web cameras is long .it is not possible to intercept table tennis ball using only image processing. Therefore the projectile motion model is employed to predict the final destination of the ball.

  20. Effective Heat Conductivity of Composite Materials with Ball Inclusions

    Directory of Open Access Journals (Sweden)

    O. V. Pugachev

    2015-01-01

    Full Text Available The process of heat conduction can be modeled via random motion of particles of heat energy, although these particles do not physically exist: they are considered as special formal objects. The speed of diffusion of heat particles in each material is proportional to its temperature conductivity coefficient. This mathematical model underlying the method of obtaining the effective heat conductivity coefficient of a composite material described in the previous paper \\Heat conductivity of composite materials with included balls of zero heat conductivity" now is being modified in order to deal with materials with various nonzero heat conductivity and capacity coefficients. Namely, when a particle passes from one material to another one, having smaller heat conductivity, it is reflected from the frontier with a certain probability.As a criterion of heat conductivity, we consider the probability that a heat particle starting on one surface of a composite layer, goes to its other surface in a time shorter than T. For a homogeneous material, this probability is calculated theoretically.For a layer of a composite, we perform a multiple computational experiment modeling heat conduction, and for the desired probability we find the confidence interval, wherefrom we obtain the confidence interval for the effective temperature conductivity coefficient, and, finally, calculate the effective heat conductivity coefficient.We have considered inclusions of materials with heat conductivity and volume heat capacity coefficients differing from those of the matrix in 3 times up or down. Ball inclusions of equal size were situated in a cubic order or chaotically. The ratio of the ball radius to the size of cubes was 0.2, 0.3, or 0.4.In series of 4300 randomly moving particles, in all cases considered, the difference between the effective heat conductivity coefficients and those calculated by other methods does not exceed a statistical error.The developed method makes

  1. Core muscle activation during Swiss ball and traditional abdominal exercises.

    Science.gov (United States)

    Escamilla, Rafael F; Lewis, Clare; Bell, Duncan; Bramblet, Gwen; Daffron, Jason; Lambert, Steve; Pecson, Amanda; Imamura, Rodney; Paulos, Lonnie; Andrews, James R

    2010-05-01

    Controlled laboratory study using a repeated-measures, counterbalanced design. To test the ability of 8 Swiss ball exercises (roll-out, pike, knee-up, skier, hip extension right, hip extension left, decline push-up, and sitting march right) and 2 traditional abdominal exercises (crunch and bent-knee sit-up) on activating core (lumbopelvic hip complex) musculature. Numerous Swiss ball abdominal exercises are employed for core muscle strengthening during training and rehabilitation, but there are minimal data to substantiate the ability of these exercises to recruit core muscles. It is also unknown how core muscle recruitment in many of these Swiss ball exercises compares to core muscle recruitment in traditional abdominal exercises such as the crunch and bent-knee sit-up. A convenience sample of 18 subjects performed 5 repetitions for each exercise. Electromyographic (EMG) data were recorded on the right side for upper and lower rectus abdominis, external and internal oblique, latissimus dorsi, lumbar paraspinals, and rectus femoris, and then normalized using maximum voluntary isometric contractions (MVICs). EMG signals during the roll-out and pike exercises for the upper rectus abdominis (63% and 46% MVIC, respectively), lower rectus abdominis (53% and 55% MVIC, respectively), external oblique (46% and 84% MVIC, respectively), and internal oblique (46% and 56% MVIC, respectively) were significantly greater compared to most other exercises, where EMG signals ranged between 7% to 53% MVIC for the upper rectus abdominis, 7% to 44% MVIC for the lower rectus abdominis, 14% to 73% MVIC for the external oblique, and 16% to 47% MVIC for the internal oblique. The lowest EMG signals were consistently found in the sitting march right exercise. Latissimus dorsi EMG signals were greatest in the pike, knee-up, skier, hip extension right and left, and decline push-up (17%-25% MVIC), and least with the sitting march right, crunch, and bent-knee sit-up exercises (7%-8% MVIC

  2. 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.

  3. The formation of collective silk balls in the spider mite Tetranychus urticae Koch.

    Directory of Open Access Journals (Sweden)

    Gwendoline Clotuche

    2011-04-01

    Full Text Available Tetranychus urticae is a phytophagous mite that forms colonies of several thousand individuals. These mites construct a common web to protect the colony. When plants become overcrowded and food resources become scarce, individuals gather at the plant apex to form a ball composed of mites and their silk threads. This ball is a structure facilitating group dispersal by wind or animal transport. Until now, no quantitative study had been done on this collective form of migration. This is the first attempt to understand the mechanisms that underlie the emergence and growth of the ball. We studied this collective behaviour under laboratory conditions on standardized infested plants. Our results show that the collective displacement and the formation of balls result from a recruitment process: by depositing silk threads on their way up to the plant apex, mites favour and amplify the recruitment toward the balls. A critical threshold (quorum response in the cumulative flow of mites must be reached to observe the emergence of a ball. At the beginning of the balls formation, mites form an aggregate. After 24 hours, the aggregated mites are trapped inside the silk balls by the complex network of silk threads and finally die, except for recently arrived individuals. The balls are mainly composed of immature stages. Our study reconstructs the key events that lead to the formation of silk balls. They suggest that the interplay between mites' density, plant morphology and plant density lead to different modes of dispersions (individual or collective and under what conditions populations might adopt a collective strategy rather than one that is individually oriented. Moreover, our results lead to discuss two aspects of the cooperation and altruism: the importance of Allee effects during colonization of new plants and the importance of the size of a founding group.

  4. Percutaneous Renal Cryoablation: Short-Axis Ice-Ball Margin as a Predictor of Outcome.

    Science.gov (United States)

    Ge, Benjamin H; Guzzo, Thomas J; Nadolski, Gregory J; Soulen, Michael C; Clark, Timothy W I; Malkowicz, Stanley B; Wein, Alan J; Hunt, Stephen J; Stavropoulos, S William

    2016-03-01

    To determine if CT characteristics of intraprocedural ice balls correlate with outcomes after cryoablation. A retrospective review was performed on 63 consecutive patients treated with renal cryoablation. Preprocedural and intraprocedural images were used to identify the size and location of renal tumors and ice balls as well as the tumor coverage and ice-ball margins. Review of follow-up imaging (1 mo and then 3-6-mo intervals) distinguished successful ablations from cases of residual tumor. Patients who underwent successful ablation (n = 50; 79%) had a mean tumor diameter of 2.5 cm (range, 0.9-4.3 cm) and mean ice-ball margin of 0.4 cm (range, 0.2-1.2 cm). Patients with residual tumor (n = 13; 21%) had a mean tumor diameter of 3.8 cm (range, 1.8-4.5 cm) and mean ice-ball margin of -0.4 cm (range, -0.9 to 0.4 cm). Residual and undertreated tumors were larger and had smaller ice-ball margins than successfully treated tumors (P ball diameters were significantly smaller after image reformatting (P ball margins of 0.15 cm had 90% sensitivity, 92% specificity, and 98% positive predictive value for successful ablation. Success was independent of tumor location or number of cryoprobes. Ice-ball margin and real-time intraprocedural reformatting could be helpful in predicting renal cryoablation outcomes. Although a 0.5-cm margin is preferred, a well-centered ice ball with a short-axis margin greater than 0.15 cm strongly correlated with successful ablation. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

  5. « Penser base-ball »

    Directory of Open Access Journals (Sweden)

    Peter Marquis

    2012-06-01

    Full Text Available Vers 1900, les grandes villes américaines se dotèrent d’associations caritatives qui firent du sport l’instrument d’une revitalisation de la nation. Fruit de divers courants intellectuels, cette sportisation des œuvres de bienfaisance toucha directement Brooklyn et « ses » Dodgers. Dès l’inauguration du stade Ebbets Field en 1913 et plus encore à partir de 1943 durant la présidence de Branch Rickey, le club des Dodgers tissa des relations intimes avec les associations caritatives du borough, notamment via sa « Fondation pour le base-ball amateur ». Les œuvres qu’elle supervisait vantaient la pratique du base-ball pour ses bénéfices physiques, mais surtout pour la socialisation qu’elle offrait, perçue comme un antidote aux inquiétudes de l’époque. « Penser base-ball » signifiait bien plus que se concentrer sur les subtilités du jeu. Arme contre la « délinquance juvénile » et le communisme, le base-ball formait l’esprit de futurs citoyens et portait les valeurs que le pays, en recomposition après 1945, célébrait alors. Cette croyance, partagée par un entre-soi d’experts brooklynois de la jeunesse, reflétait et façonnait tout à la fois les attitudes et les représentations, notamment à l’égard des jeunes Africains-Américains, premiers oubliés de l’action caritative du club.Around 1900, large American cities saw the rise of charity organizations that instrumentalized sports to revitalize the nation. An outgrowth of various intellectual movements, the sportization of voluntary organizations directly affected Brooklyn and “its” Dodgers. From the opening of Ebbets Field in 1913, but especially from 1943 during the presidency of Branch Rickey, the Dodgers front-office cultivated strong ties with the borough’s charities via its own Brooklyn Amateur Baseball Foundation. The organizations it supervised lauded baseball for its physical benefits but especially for the socialization it

  6. Singularities at the contact point of two kissing Neumann balls

    Science.gov (United States)

    Nazarov, Sergey A.; Taskinen, Jari

    2018-02-01

    We investigate eigenfunctions of the Neumann Laplacian in a bounded domain Ω ⊂Rd, where a cuspidal singularity is caused by a cavity consisting of two touching balls, or discs in the planar case. We prove that the eigenfunctions with all of their derivatives are bounded in Ω ‾, if the dimension d equals 2, but in dimension d ≥ 3 their gradients have a strong singularity O (| x - O|-α), α ∈ (0 , 2 -√{ 2 } ] at the point of tangency O. Our study is based on dimension reduction and other asymptotic procedures, as well as the Kondratiev theory applied to the limit differential equation in the punctured hyperplane R d - 1 ∖ O. We also discuss other shapes producing thinning gaps between touching cavities.

  7. Highly sensitive straightness measurement system using a ball-lens

    International Nuclear Information System (INIS)

    Lee, Minho; Yang, Hyun-Ik; Cho, Nahm-Gyoo

    2016-01-01

    In this paper, a new and simple optical technique to accurately measure the straightness errors of a linear stage is proposed. To improve the performance, including the measurement sensitivity and resolution of the measurement system, and to simultaneously measure two-dimensional straightness errors (2D straightness errors), an optical system was designed using a laser, a retro-reflector, a ball-lens, and a two-dimensional position sensitive detector (2D PSD). The characteristics of the measurement system were analytically and experimentally investigated. A prototype measurement system was manufactured based on the investigated results, and the performances of this system have been tested. The measuring performance of the system was easily improved by about 12 times using the proposed technique and it can be further improved. It is shown that the proposed technique can easily and effectively improve the performance of a conventional straightness measurement system based on the geometric optical method using a PSD. (paper)

  8. Social forces for team coordination in ball possession game

    Science.gov (United States)

    Yokoyama, Keiko; Shima, Hiroyuki; Fujii, Keisuke; Tabuchi, Noriyuki; Yamamoto, Yuji

    2018-02-01

    Team coordination is a basic human behavioral trait observed in many real-life communities. To promote teamwork, it is important to cultivate social skills that elicit team coordination. In the present work, we consider which social skills are indispensable for individuals performing a ball possession game in soccer. We develop a simple social force model that describes the synchronized motion of offensive players. Comparing the simulation results with experimental observations, we uncovered that the cooperative social force, a measure of perception skill, has the most important role in reproducing the harmonized collective motion of experienced players in the task. We further developed an experimental tool that facilitates real players' perceptions of interpersonal distance, revealing that the tool improves novice players' motions as if the cooperative social force were imposed.

  9. Building micro-soccer-balls with evaporating colloidal fakir drops

    Science.gov (United States)

    Gelderblom, Hanneke; Marín, Álvaro G.; Susarrey-Arce, Arturo; van Housselt, Arie; Lefferts, Leon; Gardeniers, Han; Lohse, Detlef; Snoeijer, Jacco H.

    2013-11-01

    Drop evaporation can be used to self-assemble particles into three-dimensional microstructures on a scale where direct manipulation is impossible. We present a unique method to create highly-ordered colloidal microstructures in which we can control the amount of particles and their packing fraction. To this end, we evaporate colloidal dispersion drops from a special type of superhydrophobic microstructured surface, on which the drop remains in Cassie-Baxter state during the entire evaporative process. The remainders of the drop consist of a massive spherical cluster of the microspheres, with diameters ranging from a few tens up to several hundreds of microns. We present scaling arguments to show how the final particle packing fraction of these balls depends on the drop evaporation dynamics, particle size, and number of particles in the system.

  10. Oscillating shells and oscillating balls in AdS

    Science.gov (United States)

    Banerjee, Avik; Kundu, Arnab; Roy, Pratik; Virmani, Amitabh

    2017-07-01

    It has recently been reported that certain thin timelike shells undergo oscillatory motion in AdS. In this paper, we compute two-point function of a probe field in the geodesic approximation in such an oscillating shell background. We confirm that the two-point function exhibits an oscillatory behaviour following the motion of the shell. We show that similar oscillatory dynamics is possible when the perfect fluid on the shell has a polytropic equation of state. Moreover, we show that certain ball like configurations in AdS also exhibit oscillatory motion and comment on how such a solution can be smoothly matched to an appropriate exterior solution. We also demonstrate that the weak energy condition is satisfied for these oscillatory configurations.

  11. Innovative in Situ Ball Mill for X-ray Diffraction.

    Science.gov (United States)

    Ban, Voraksmy; Sadikin, Yolanda; Lange, Michael; Tumanov, Nikolay; Filinchuk, Yaroslav; Černý, Radovan; Casati, Nicola

    2017-12-19

    The renewed interest of mechanochemistry as an ecofriendly synthetic route has inspired original methodologies to probe reactions, with the aim to rationalize unknown mechanisms. Recently, Friščić et al. ( Nat. Chem. 2013 , 5 , 66 - 73 , DOI: 10.1038/nchem.1505 ) monitored the progress of milling reactions by synchrotron X-ray powder diffraction (XRPD). For the first time, it was possible to acquire directly information during a mechanochemical process. This new methodology is still in its early stages, and its development will definitively transform the fundamental understanding of mechanochemistry. A new type of in situ ball mill setup has been developed at the Materials Science beamline (Swiss Light Source, Paul Scherrer Institute, Switzerland). Its particular geometry, described here in detail, results in XRPD data displaying significantly lower background and much sharper Bragg peaks, which in turn allow more sophisticated analysis of mechanochemical processes, extending the limits of the technique.

  12. [Hematologic features of olympic volley-ball athletes].

    Science.gov (United States)

    Faintuch, J J; Lotufo, P A; Gilberto, J

    1994-01-01

    Athletes tend to have lower hemoglobin concentrations than sedentary counterparts. Sports anemia is used to describe both pseudodilutional anemia and the true anemia of athletes. Pseudodilutional anemia is a beneficial adaptation to endurance training; the two most common causes of true anemia are iron deficiency and intravascular hemolysis. We used questionnaires, physical examination and laboratory investigation to study 16 volley-ball highly trained athletes and 23 outpatients with the same ages and gender that have not had any significant disease. All athletes and patients had Hb > 13 g/dl; the athletes hab Hb and hematocrit lower than the control patients; 25% of the athletes had both total and indirect bilirubin increased. Seven patients and only one athlete had intestinal parasitic infestation. These data support the idea that in São Paulo-Brazil among athletes overt anemia is uncommon but the volleyball athletes are in a borderline anemic state.

  13. 76 FR 22372 - Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United Kingdom...

    Science.gov (United States)

    2011-04-21

    ...-804, A-412-801] Ball Bearings and Parts Thereof From France, Germany, Italy, Japan, and the United... administrative reviews of the antidumping duty orders on ball bearings and parts thereof from France, Germany...- in-interest to Schaeffler KG with respect to the order on ball bearings and parts thereof from...

  14. 76 FR 35401 - Ball Bearings and Parts Thereof From Japan and the United Kingdom: Notice of Court Decision Not...

    Science.gov (United States)

    2011-06-17

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-588-804, A-412-801] Ball Bearings and... orders on ball bearings and parts thereof from Japan and the United Kingdom. On April 20, [[Page 35402... redetermination that revocation of the antidumping duty orders on ball bearings and parts thereof from Japan and...

  15. 76 FR 41761 - Ball Bearings and Parts Thereof From Japan and the United Kingdom: Revocation of Antidumping Duty...

    Science.gov (United States)

    2011-07-15

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-588-804, A-412-801] Ball Bearings and... Commerce (the Department) is revoking the antidumping duty orders on ball bearings and parts thereof from...: Background On May 15, 1989, the Department published the antidumping duty orders on ball bearings and parts...

  16. 75 FR 41435 - Ball Bearings and Parts Thereof From Germany: Notice of Court Decision Not in Harmony With Final...

    Science.gov (United States)

    2010-07-16

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-428-801] Ball Bearings and Parts... antidumping duty order on ball bearings and parts thereof from Germany. See SKF USA Inc., v. United States... administrative reviews of the antidumping duty orders on ball bearings and parts thereof from France, Germany...

  17. Real-Time Visual Feedback of Airflow in Voice Training: Aerodynamic Properties of Two Flow Ball Devices.

    Science.gov (United States)

    Lã, Filipa M B; Wistbacka, Greta; Andrade, Pedro Amarante; Granqvist, Svante

    2017-05-01

    Flow ball devices have been used as teaching tools to provide visual real-time feedback of airflow during singing. This study aims at exploring static back pressure and ball height as function of flow for two devices, marketed as flow ball and floating ball game. This is a comparative descriptive study. A flow-driven vocal tract simulator was used to investigate the aerodynamic properties of these two devices, testing them for four different ball sizes. The flow range investigated was between 0 and 0.5 L/s. Audio, flow, pressure, and ball height were recorded. The flow pressure profiles for both tested devices were similar to those observed in previous studies on narrow tubes. For lifting the ball, both devices had a flow and a pressure threshold. The tested floating ball game required considerably higher back pressure for a given flow as compared with the flow ball. Both tested devices have similar effects on back pressure as straws of 3.7 and 3.0 mm in diameter for the flow ball and the floating ball game, respectively. One might argue that both devices could be used as tools for practicing semi-occluded vocal tract exercises, with the additional benefit of providing real-time visual feedback of airflow during phonation. The flow threshold, combined with the flow feedback, would increase awareness of flow, rather than of pressure, during exercises using a flow ball device. Published by Elsevier Inc.

  18. Do the ball-ended probe cause less damage than sharp explorers?—An ultrastructural analysis

    OpenAIRE

    Mattos-Silveira, Juliana; Oliveira, Marina Monreal; Matos, Ronilza; Moura-Netto, Cacio; Mendes, Fausto Medeiros; Fraga, Mariana Minatel Braga

    2016-01-01

    Abstract Background No evidence about damage caused by ball-ended probes on tooth is available. No study compared probing defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. This exploratory study aimed to compare ultrastructural defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. Me...

  19. KINEMATICS AND DYNAMICS OF BALLS WHILE BEING POLISHED BETWEEN MISALIGNED DISKS IN DRIVEN SEPARATOR

    Directory of Open Access Journals (Sweden)

    K. G. Schetnikovich

    2007-01-01

    Full Text Available The paper contains description of tool design which is used for rough polishing of balls made of brittle materials. This tool consists of top disk, which is fi-eely set on pouring bearing of the separator shaft, and a bottom disk with elastic coating. Theoretical investigations of ball kinematics have permitted to determine an angular velocity of the balls in the machining zone, value and direction oi slipping speed with respect to the tool.it has been determined that even change of the position of bail rotation instantaneous axis relative to the separator is reached at equality of angular velocities of the bottom disk and the separator. When the top disk is freely set slipping speed is equal for all the balls of the machined lot. When the top disk is stationary slipping speed is significantly increasing however its value becomes variable and depends on ball distance to separator rotation axis.The presented equations of ball dynamics in the machining zone have made it possible to detennine a cohesive force with the bottom disk, frictional forces against the top disk and separator. Recommendations on selection of machining modes at initial and final stages of ball polishing are given in the paper.

  20. Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Ning, Rong [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Chen, Ding, E-mail: ma97chen@hotmail.com [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Qianxia [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Bian, Zhibing; Dai, Haixiong; Zhang, Chi [Jiangsu Jinling Special Paint Co., Ltd., Yangzhou 225212 (China)

    2014-10-15

    Highlights: • TiH{sub 2} was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH{sub 2} with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process.

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

    Science.gov (United States)

    Luo, Yong; Ran, Guang; Chen, Nanjun; Shen, Qiang; Zhang, Yaoli

    2016-10-15

    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.

  2. Fabrication and Study of Micro Monolithic Tungsten Ball Tips for Micro/Nano-CMM Probes

    Directory of Open Access Journals (Sweden)

    Ruijun Li

    2018-03-01

    Full Text Available Micro ball tips with high precision, small diameter, and high stiffness stems are required to measure microstructures with high aspect ratio. Existing ball tips cannot meet such demands because of their weak qualities. This study used an arc-discharge melting method to fabricate a micro monolithic tungsten ball tip on a tungsten stylus. The principles of arc discharge and surface tension phenomenon were introduced. The experimental setup was designed and established. Appropriate process parameters, such as impulse voltage, electro discharge time, and discharge gap were determined. Experimental results showed that a ball tip of approximately 60 µm in diameter with less than 0.6 µm roundness error and 0.6 µm center offset could be realized on a 100 µm-diameter tungsten wire. The fabricated micro ball tip was installed on a homemade probe, touched by high-precision gauge blocks in different directions. A repeatability of 41 nm (K = 2 was obtained. Several interesting phenomena in the ball-forming process were also discussed. The proposed method could be used to fabricate a monolithic probe ball tip, which is necessary for measuring microstructures.

  3. Do the ball-ended probe cause less damage than sharp explorers?-An ultrastructural analysis.

    Science.gov (United States)

    Mattos-Silveira, Juliana; Oliveira, Marina Monreal; Matos, Ronilza; Moura-Netto, Cacio; Mendes, Fausto Medeiros; Braga, Mariana Minatel

    2016-03-22

    No evidence about damage caused by ball-ended probes on tooth is available. No study compared probing defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. This exploratory study aimed to compare ultrastructural defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. Forty-nine primary extracted teeth were tactile examined as performed for caries activity assessment. Surfaces were randomly divided into groups based on probe type (ball-ended probe or sharp explorer). Two examiners probed different surfaces using the sharp explorer and the ball-ended probe. The order for examination was randomly determined. Images were captured using environmental scanning electron microscopy (ESEM) before and after probing. Two external examiners evaluated independently the ESEM images and scored them as: 0) no damage, 1) slight marks, 2) distinct marks, 3) marks with discontinuity, 4) enamel break-offs. Multilevel Poisson regression models were used to analyze associations between probing ultrastructural damage and surface type, baseline condition and probe type. Prevalence ratios (PR) were calculated with 95 % confidence interval (CI). The most common defects observed on the dental surfaces were probing marks without discontinuity (scores 1 and 2). Ball-ended probes caused significantly less severe damage than sharp explorers (PR: 0.28; CI: 0.11-0.76, p = 0.01). Ball-ended probes cause less damage than sharp explorers when probing gently dental surfaces of primary teeth.

  4. Analysis of grease contamination influence on the internal radial clearance of ball bearings by thermographic inspection

    Directory of Open Access Journals (Sweden)

    Mišković Žarko Z.

    2016-01-01

    Full Text Available One of the most important factors influencing ball bearings service life is its internal radial clearance. However, this parameter is also very complex because it depends on applied radial load and ball bearings dimensions, surface finish and manufacturing materials. Thermal condition of ball bearings also significantly affects internal radial clearance. Despite many researches performed in order to find out relevant facts about different aspects of ball bearings thermal behaviour, only few of them are dealing with the real working conditions, where high concentration of solid contaminant particles is present. That’s why the main goal of research presented in this paper was to establish statistically significant correlation between ball bearings temperatures, their working time and concentration of contaminant particles in their grease. Because of especially difficult working conditions, the typical conveyor idlers bearings were selected as representative test samples and appropriate solid particles from open pit coal mines were used as artificial contaminants. Applied experimental methodology included thermographic inspection, as well as usage of custom designed test rig for ball bearings service life testing. Finally, by obtained experimental data processing in advanced software, statistically significant mathematical correlation between mentioned bearings characteristics was determined and applied in commonly used internal radial clearance equation. That is the most important contribution of performed research - the new equation and methodology for ball bearings internal clearance determination which could be used for eventual improvement of existing bearings service life equations. [Projekat Ministarstva nauke Republike Srbije, br. TR35029 i br. TR14033

  5. A Tsunami Ball Approach to Storm Surge and Inundation: Application to Hurricane Katrina, 2005

    Directory of Open Access Journals (Sweden)

    Steven N. Ward

    2009-01-01

    Full Text Available Most analyses of storm surge and inundation solve equations of continuity and momentum on fixed finite-difference/finite-element meshes. I develop a completely new approach that uses a momentum equation to accelerate bits or balls of water over variable depth topography. The thickness of the water column at any point equals the volume density of balls there. In addition to being more intuitive than traditional methods, the tsunami ball approach has several advantages. (a By tracking water balls of fixed volume, the continuity equation is satisfied automatically and the advection term in the momentum equation becomes unnecessary. (b The procedure is meshless in the finite-difference/finite-element sense. (c Tsunami balls care little if they find themselves in the ocean or inundating land. (d Tsunami ball calculations of storm surge can be done on a laptop computer. I demonstrate and calibrate the method by simulating storm surge and inundation around New Orleans, Louisiana caused by Hurricane Katrina in 2005 and by comparing model predictions with field observations. To illustrate the flexibility of the tsunami ball technique, I run two “What If” hurricane scenarios—Katrina over Savannah, Georgia and Katrina over Cape Cod, Massachusetts.

  6. Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

    International Nuclear Information System (INIS)

    Ning, Rong; Chen, Ding; Zhang, Qianxia; Bian, Zhibing; Dai, Haixiong; Zhang, Chi

    2014-01-01

    Highlights: • TiH 2 was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH 2 with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process

  7. Pink Cricket Balls Through Rose-Tinted Glasses: Enhancing Interceptive Timing.

    Science.gov (United States)

    Adie, Joshua M; Arnold, Derek H

    2017-01-01

    Cricket is a popular but potentially dangerous sport. It is played with a hard ball that can travel at great speeds. Serious injuries, including fatalities, have occurred when balls have struck participants. The game is traditionally played during daylight with a dark red ball, but recent games have been played during the day and at night using a 'pink' ball. We have reported data that seemed to justify concerns raised regarding the visibility of these new pink balls, as they were revealed to have a very low luminance contrast against pertinent backgrounds during twilight. Here, we report on the findings of a psychophysical experiment, wherein we mimicked twilight lighting conditions in an interceptive timing experiment using a pink moving disc as an analogue for pink cricket balls. We show that interceptive timing performance is diminished in conditions that mimic twilight. More importantly, we show that wearing glasses with a rose-tinted filter can alleviate this adverse impact by enhancing the luminance contrast of the pink 'ball' relative to pertinent backgrounds.

  8. 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.

  9. Training Level Does Not Affect Auditory Perception of The Magnitude of Ball Spin in Table Tennis

    Directory of Open Access Journals (Sweden)

    Santos Daniel P. R.

    2017-01-01

    Full Text Available Identifying the trajectory and spin of the ball with speed and accuracy is critical for good performance in table tennis. The aim of this study was to analyze the ability of table tennis players presenting different levels of training/experience to identify the magnitude of the ball spin from the sound produced when the racket hit the ball. Four types of “forehand” contact sounds were collected in the laboratory, defined as: Fast Spin (spinning ball forward at 140 r/s; Medium Spin (105 r/s; Slow Spin (84 r/s; and Flat Hit (less than 60 r/s. Thirty-four table tennis players of both sexes (24 men and 10 women aged 18-40 years listened to the sounds and tried to identify the magnitude of the ball spin. The results revealed that in 50.9% of the cases the table tennis players were able to identify the ball spin and the observed number of correct answers (10.2 was significantly higher (χ2 = 270.4, p <0.05 than the number of correct answers that could occur by chance. On the other hand, the results did not show any relationship between the level of training/experience and auditory perception of the ball spin. This indicates that auditory information contributes to identification of the magnitude of the ball spin, however, it also reveals that, in table tennis, the level of training does not interfere with the auditory perception of the ball spin.

  10. Influence of the cage on friction torque in low loaded thrust ball bearing operating in dry conditions

    Science.gov (United States)

    Olaru, D.; Balan, M. R.; Tufescu, A.

    2016-08-01

    The authors investigated analytically and experimentally the friction torque in a modified thrust ball bearing operating at very low axial load in dry conditions by using only three balls and a cage. The experiments were conducted by using spin-down methodology. The results evidenced the influence of the sliding friction between the cage and the balls on the total friction torque. It was concluded that at very low loads the friction between cage and balls in a thrust ball bearing has an important contribution on total friction torque.

  11. 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...

  12. 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.

  13. Pengaruh Ball Peening terhadap Kekerasan Baja Tahan Karat AISI 316L

    Directory of Open Access Journals (Sweden)

    Teguh Dwi Widodo

    2017-03-01

    Full Text Available In this work, ball peening was performed in order to evaluate its effect on the AISI 316L hardness. The process was conducted by employing AISI E52100 Chrome Steel ball which has hardness 752 HVN as bomber. In this research ball peening process was performed at three different nozzle pressure (6, 7, and 8 bar for 5 minutes. Vickers Micro Hardness Tester and Digital Optical Microscope was used to characterize the samples hardness and grains structure respectively. The results showed that the hardness of AISI 316L was improved. It may due to plastic deformation which toke places on its grains.

  14. The construction design of ball bearings used in the control rod driving mechanisms of PWRs

    International Nuclear Information System (INIS)

    Leng Chengmu; Huang Chongming; Chen Jianting.

    1986-01-01

    According to the operation conditions of ball bearings used in the control rod driving mechanisms of PWRs, this paper has analysed and discussed the problems that must be taken into account in the construction design of this ball bearing. It includes: a discussion about the reasonable selection of construction parameters of the bearing, deduction of the relationship between bearing clearance and contact angle, and the emphasis on the significance of assembling accuracy and torque measurement in the assurance of operational performance of the bearings. These experiences may be somewhat valuable for the design and application of this kind of ball bearing

  15. Ball tip technique for thoracic pedicle screw placement in patients with adolescent idiopathic scoliosis.

    Science.gov (United States)

    Watanabe, Kota; Matsumoto, Morio; Tsuji, Takashi; Ishii, Ken; Takaishi, Hironari; Nakamura, Masaya; Toyama, Yoshiaki; Chiba, Kazuhiro

    2010-08-01

    The aim in this study was to evaluate the efficacy of the ball tip technique in placing thoracic pedicle screws (TPSs), as compared with the conventional freehand technique, in both a cadaveric study and a clinical study of patients with adolescent idiopathic scoliosis. Although posterior spinal surgery using TPSs has been widely applied, these screws are associated with the potential risk of vascular, pulmonary, or neurological complications. To further enhance the accuracy and safety of TPS placement, the authors developed the ball tip technique. After creating an appropriate starting point for probe insertion, a specially designed ball tip probe consisting of a ball-shaped tip with a flexible metal shaft is used to make a guide hole into the pedicle. Holding the probe with the fingertips while using an appropriate amount of pressure or by tapping it gently and continuously with a hammer, one can safely insert the ball tip probe into the cancellous channel in the pedicle. In a cadaveric study, 5 spine fellows with similar levels of experience in placing TPSs applied the ball tip or the conventional technique to place screws in 5 cadavers with no spinal deformities. The incidence of misplaced screws was evaluated by dissecting the spines. In a clinical study, 40 patients with adolescent idiopathic scoliosis underwent posterior surgery with TPS placement via the ball tip or conventional technique (20 patients in each treatment group). The accuracy of the TPS placements was evaluated on postoperative axial CT scanning. In the cadaveric study, 100 TPSs were evaluated, and the incidence of misplaced screws was 14% in the ball tip group and 34% in the conventional group (p = 0.0192). In the clinical study, 574 TPSs were evaluated. One hundred seventy-one intrapedicular screws (67%) were recognized in the conventional group and 288 (90%) in the ball tip group (p ball tip groups, the respective numbers of TPSs with a pedicle breach of 2 mm were 32 (13%) and 9 (3%; p ball

  16. Golf Balls, Boomerangs and Asteroids The Impact of Missiles on Society

    CERN Document Server

    Kaye, Brian H

    1996-01-01

    Exciting reading for anyone with a curious mind!. 'Walking one day by a golf course in Wisconsin, I was startled to hear a sharp bang as a golf ball narrowly missed my head and hit a tree. My companion cheerfully remarked, 'That could have killed you, you know.' I picked up the innocent looking little white ball and looked at it with new respect.'. Prompted by this perilous experience, Brian Kaye has written a delightful and informative book on the design and behavior of different kinds of missiles from golf balls, arrows, and slingshots to comets and rockets to outer space. You'll learn about

  17. Use of Ball Blanket in attention-deficit/hyperactivity disorder sleeping problems

    DEFF Research Database (Denmark)

    Hvolby, Allan; Bilenberg, Niels

    2011-01-01

    Objectives: Based on actigraphic surveillance, attention-deficit/hyperactivity disorder (ADHD) symptom rating and sleep diary, this study will evaluate the effect of Ball Blanket on sleep for a sample of 8-13-year-old children with ADHD. Design: Case-control study. Setting: A child and adolescent...... Blanket. The time it takes to fall asleep when using the Ball Blanket is found to be at the same level as the healthy control subjects. Teacher rating of symptoms show an improvement in both activity levels and attention span of approximately 10% after using the Ball Blankets. Conclusions: The results...

  18. An analytical model for force prediction in ball nose micro milling of inclined surfaces

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2010-01-01

    Ball nose micro milling is a key process for the generation of free form surfaces and inclined surfaces often present in mould inserts for micro replication. This paper presents a new cutting force model for ball nose micro milling that is capable of taking into account the effect of the edge rad...... radius and the effect of the surface topography due to the previous milling passes. The model is completely analytical can be applied to ball end micro milling of slanted surfaces for any value of the surface inclination angle relative to the tool axis....

  19. 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

  20. Low-temperature radiation-resistant material for ball-bearing retainers

    Science.gov (United States)

    Desau, P. O.; Emmons, W. F.

    1970-01-01

    Radiation resistant material, made of polyimide polymers and S-glass cloth, is used in ball bearing retainers for extreme environments. Material displays satisfactory wear resistance, lubricity, and stability. Results of comparative tests with fluorocarbon materials are given.