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Sample records for collision i2-polymeric liquid

  1. Droplet Collision in Liquid Propellant Combustion.

    DTIC Science & Technology

    1995-10-25

    aims to gain fundamental understanding on the mechanisms governing the observed phenomena of permanent coalescence, bouncing , and separation upon...slight deformation, (II) bouncing , (III) coalescence with substantial deformation, (IV) coalescence followed by separation for near head-on collisions

  2. Probing the microscopic corrugation of liquid surfaces with gas-liquid collisions

    NASA Technical Reports Server (NTRS)

    King, Mackenzie E.; Nathanson, Gilbert M.; Hanning-Lee, Mark A.; Minton, Timothy K.

    1993-01-01

    We have measured the directions and velocities of Ne, Ar, and Xe atoms scattering from perfluorinated ether and hydrocarbon liquids to probe the relationship between the microscopic roughness of liquid surfaces and gas-liquid collision dynamics. Impulsive energy transfer is governed by the angle of deflection: head-on encounters deposit more energy than grazing collisions. Many atoms scatter in the forward direction, particularly at glancing incidence. These results imply that the incoming atoms recoil locally from protruding C-H and C-F groups in hard spherelike collisions.

  3. Dynamics of Non-Newtonian Liquid Droplet Collision

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Yang, Vigor

    2012-11-01

    Collision of Newtonian liquid droplets has been extensively investigated both experimentally and numerically for decades. Limited information, however, is available about non-Newtonian droplet collision dynamics. In the present work, high-fidelity numerical simulations were performed to study the situation associated with shear-thinning non-Newtonian liquids. The formulation is based on a complete set of conservation equations for the liquid and the surrounding gas phases. An improved volume-of-fluid (VOF) method, combined with an innovative topology-oriented adaptive mesh refinement (TOAMR) technique, was developed and implemented to track the interfacial dynamics. The complex evolution of the droplet surface over a broad range of length scales was treated accurately and efficiently. In particular, the thin gas film between two approaching droplets and subsequent breakup of liquid threads were well-resolved. Various types of droplet collision were obtained, including coalescence, bouncing, and reflexive and stretching separations. A regime diagram was developed and compared with that for Newtonian liquids. Fundamental mechanisms and key parameters that dictate droplet behaviors were identified. In addition, collision-induced atomization was addressed. This work was sponsored by the U.S. Army Research Office under the Multi-University Research Initiative under contract No. W911NF-08-1-0124. The support and encouragement provided by Dr. Ralph Anthenien are gratefully acknowledged.

  4. Creating The Perfect Liquid In Heavy-Ion Collisions

    SciTech Connect

    Jacak, B.; Steinberg, P.

    2010-05-01

    In 2005 the four experimental groups at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) announced that collisions of gold nuclei at ultrarelativistic energies produced a 'perfect liquid' of quarks and gluons. That's something quite different from the gaseous quark-gluon state theorists and experimenters were expecting from quantum chromodynamics, the standard theory of the strong interaction.

  5. Multiscale Simulation of Gas Film Lubrication During Liquid Droplet Collision

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Khare, Prashant; Ma, Dongjun; Yang, Vigor

    2012-02-01

    Droplet collision plays an elementary role in dense spray combustion process. When two droplets approach each other, a gas film forms in between. The pressure generated within the film prevents motion of approaching droplets. This fluid mechanics is fluid film lubrication that occurs when opposing bearing surfaces are completely separated by fluid film. The lubrication flow in gas film decides the collision outcome, coalescence or bouncing. Present study focuses on gas film drainage process over a wide range of Weber numbers during equal- and unequal-sized droplet collision. The formulation is based on complete set of conservation equations for both liquid and surrounding gas phases. An improved volume-of-fluid technique, augmented by an adaptive mesh refinement algorithm, is used to track liquid/gas interfaces. A unique thickness-based refinement algorithm based on topology of interfacial flow is developed and implemented to efficiently resolve the multiscale problem. The grid size on interface is up O(10-4) of droplet size with a max resolution of 0.015 μm. An advanced visualization technique using the Ray-tracing methodology is used to gain direct insights to detailed physics. Theories are established by analyzing the characteristics of shape changing and flow evolution.

  6. Measurement of surface tension of liquid microdroplets through observation of droplet collision

    NASA Astrophysics Data System (ADS)

    Hayakawa, Daichi; Hirano, Taichi; Mitani, Shujiro; Sakai, Keiji

    2017-07-01

    We investigate the applicability of measuring surface tension of liquid microdroplets by analyzing their oscillatory behavior induced by droplet collision. The eigenfrequency of droplet oscillation reflects surface tension for small-amplitude oscillation. In this study, the oscillation frequencies of ethanol-ethanol and water-water droplet collisions are measured by direct observation. We experimentally verify that surface tension can be measured for deformation smaller than 10% of the droplet radius. The collision between ethanol-water droplets is also analyzed. The eigenfrequency induced by unlike-droplet collision exhibits a peculiar behavior, which may be attributed to the temporal hybrid structure of a combined droplet.

  7. A stochastic, local mode study of neon-liquid surface collision dynamics.

    PubMed

    Packwood, Daniel M; Phillips, Leon F

    2011-01-14

    Equations of motion for a fast, light rare gas atom passing over a liquid surface are derived and used to infer the dynamics of neon collisions with squalane and perfluorinated polyether surfaces from experimental data. The equations incorporate the local mode model of a liquid surface via a stochastic process and explicitly account for impulsive collisional energy loss to the surface. The equations predict angular distributions for scattering of neon that are in good quantitative agreement with experimental data. Our key dynamical conclusions are that experimental angular distributions derive mainly from local mode surface topography rather than from structural features of individual surface molecules, and that the available data for these systems can be accounted for almost exclusively by single collisions between neon atoms and the liquid surface.

  8. Coloring Rate of Phenolphthalein by Reaction with Alkaline Solution Observed by Liquid-Droplet Collision.

    PubMed

    Takano, Yuuka; Kikkawa, Shigenori; Suzuki, Tomoko; Kohno, Jun-ya

    2015-06-11

    Many important chemical reactions are induced by mixing two solutions. This paper presents a new way to measure rates of rapid chemical reactions induced by mixing two reactant solutions using a liquid-droplet collision. The coloring reaction of phenolphthalein (H2PP) by a reaction with NaOH is investigated kinetically. Liquid droplets of H2PP/ethanol and NaOH/H2O solutions are made to collide, which induces a reaction that transforms H2PP into a deprotonated form (PP(2-)). The concentration of PP(2-) is evaluated from the RGB values of pixels in the colored droplet images, and is measured as a function of the elapsed time from the collision. The obtained rate constant is (2.2 ± 0.7) × 10(3) M(-1) s(-1), which is the rate constant for the rate-determining step of the coloring reaction of H2PP. This method was shown to be applicable to determine rate constants of rapid chemical reactions between two solutions.

  9. Binary collision approximations for the memory function for density fluctuations in equilibrium atomic liquids

    NASA Astrophysics Data System (ADS)

    Noah, Joyce E.

    Time correlation functions of density fluctuations of liquids at equilibrium can be used to relate the microscopic dynamics of a liquid to its macroscopic transport properties. Time correlation functions are especially useful since they can be generated in a variety of ways, from scattering experiments to computer simulation to analytic theory. The kinetic theory of fluctuations in equilibrium liquids is an analytic theory for calculating correlation functions using memory functions. In this work, we use a diagrammatic formulation of the kinetic theory to develop a series of binary collision approximations for the collisional part of the memory function. We define binary collisions as collisions between two distinct density fluctuations whose identities are fixed during the duration of a collsion. R approximations are for the short time part of the memory function, and build upon the work of Ranganathan and Andersen. These approximations have purely repulsive interactions between the fluctuations. The second type of approximation, RA approximations, is for the longer time part of the memory function, where the density fluctuations now interact via repulsive and attractive forces. Although RA approximations are a natural extension of R approximations, they permit two density fluctuations to become trapped in the wells of the interaction potential, leading to long-lived oscillatory behavior, which is unphysical. Therefore we consider S approximations which describe binary particles which experience the random effect of the surroundings while interacting via repulsive or repulsive and attractive interactions. For each of these approximations for the memory function we numerically solve the kinetic equation to generate correlation functions. These results are compared to molecular dynamics results for the correlation functions. Comparing the successes and failures of the different approximations, we conclude that R approximations give more accurate intermediate and

  10. Collision and coalescence of liquid drops in a dynamically active ambient fluid

    NASA Astrophysics Data System (ADS)

    Sambath, Krishnaraj; Subramani, Hariprasad; Basaran, Osman

    2012-11-01

    The fluid dynamics of the collision and coalescence of liquid drops has intrigued scientists and engineers for more than a century owing to its ubiquitousness in nature, e.g. raindrop coalescence, and industry, e.g. breaking of emulsions in the oil and gas industry. The complexity of the underlying dynamics, e.g. occurrence of hydrodynamic singularities, has required study of the problem at different scales - macroscopic, mesoscopic and molecular - using stochastic and deterministic methods. In this work, we adopt a multiscale, deterministic method to simulate the approach, collision, and eventual coalescence of two drops where the drops as well as the ambient fluid are incompressible, Newtonian fluids. The free boundary problem governing the dynamics consists of the Navier-Stokes system and associated initial and boundary conditions that have been augmented to account for the effects of disjoining pressure as the separation between the drops becomes of the order of a few hundred nanometers. This free boundary problem is solved by a Galerkin finite element-based algorithm. The approach and results to be reported build on earlier work by Leal and coworkers, and are used to identify conditions conducive for coalescence in terms of flow and fluid properties.

  11. Collision Dynamics and Internal Mixing of Droplets of Non-Newtonian Liquids

    NASA Astrophysics Data System (ADS)

    Sun, Kai; Zhang, Peng; Law, Chung K.; Wang, Tianyou

    2015-11-01

    The efficient internal mixing of colliding droplets upon coalescence is critical to various technological processes such as color manipulation in ink-jet printing and the initiation of the liquid-phase reaction of gelled hypergolic propellants in rocket engines. Recognizing that such processes can be optimized by varying the impact inertia as well as employing fluids of non-Newtonian rheology, the head-on collision, coalescence, and internal mixing pattern between two impacting equal-sized droplets of non-Newtonian fluids is computationally investigated by using the lattice Boltzmann method. Results show that, with increasing non-Newtonian effects, droplet deformation and separation following coalescence is promoted for shear-thinning fluids, while permanent coalescence allowing an extended duration for mixing is promoted for shear-thickening fluids. Furthermore, large-scale internal mixing is promoted for the colliding droplets with larger shear-thinning disparity, while coalescence and mixing is synergistically facilitated for the collision between a shear-thinning droplet and a shear-thickening droplet. The individual and coupled influences of viscosity on the droplet deformation and impact inertia, internal motion, viscous loss, and merging of the colliding interfaces leading to the observed outcomes are mechanistically identified and described.

  12. High velocity proton collision with liquid lithium: a time dependent density functional theory study.

    PubMed

    Bi, Gang; Kang, Jun; Wang, Lin-Wang

    2017-03-29

    Liquid lithium is often used as a coating material in fusion reaction chambers, where it is under constant bombardment from high speed neutrons and protons. However, numerous fundamental questions are unanswered, for example whether a single proton impact can cause Li atom sputtering, and what is the electron excitation energy profile after a collision particularly for extremely high energy projectiles. Herein, we use a real-time dependent density functional method to study these questions for proton energies in the range of 30 eV to 1 MeV. The calculated stopping power agrees well with experiment, and it is found that the stopping power cannot be described by the single electron exciting spectrum based on the adiabatic eigen energies, and Li atom sputtering is not observed within our simulation time.

  13. Appropriate choice of collision-induced dissociation energy for qualitative analysis of notoginsenosides based on liquid chromatography hybrid ion trap time-of-flight mass spectrometry.

    PubMed

    Wang, Guang-Ji; Fu, Han-Xu; Xiao, Jing-Cheng; Ye, Wei; Rao, Tai; Shao, Yu-Hao; Kang, Dian; Xie, Lin; Liang, Yan

    2016-04-01

    Liquid chromatography hybrid ion trap/time-of-flight mass spectrometry possessesd both the MS(n) ability of ion trap and the excellent resolution of a time-of-flight, and has been widely used to identify drug metabolites and determine trace multi-components for in natural products. Collision energy, one of the most important factors in acquiring MS(n) information, could be set freely in the range of 10%-400%. Herein, notoginsenosides were chosen as model compounds to build a novel methodology for the collision energy optimization. Firstly, the fragmental patterns of the representatives for the authentic standards of protopanaxadiol-type and protopanaxatriol-type notoginsenosides authentic standards were obtained based on accurate MS(2) and MS(3) measurements via liquid chromatography hybrid ion trap/time-of-flight mass spectrometry. Then the extracted ion chromatograms of characteristic product ions of notoginsenosides in Panax Notoginseng Extract, which were produced under a series of collision energies and, were compared to screen out the optimum collision energies values for MS(2) and MS(3). The results demonstrated that the qualitative capability of liquid chromatography hybrid ion trap/time-of-flight mass spectrometry was greatly influenced by collision energies, and 50% of MS(2) collision energy was found to produce the highest collision-induced dissociation efficiency for notoginsenosides. BesidesAddtionally, the highest collision-induced dissociation efficiency appeared when the collision energy was set at 75% in the MS(3) stage.

  14. Modeling of a hollow-cone liquid spray including droplet collisions

    NASA Astrophysics Data System (ADS)

    Asheim, J. P.; Kirwan, J. E.; Peters, J. E.

    1987-01-01

    A spray model is used to determine the characteristics of a hollow-cone water spray injected from a pressure jet swirl atomizer into uniform air flow traveling through a vertical wind tunnel. The model simulates droplets stochastically and accounts for 'drop-drop' effects by permitting droplet collisions which result in coalescence or breakup. This investigation's objectives are to study the model's droplet tracking capabilities with special emphasis placed on the effects of droplet collisions. It is concluded that the collision model's results for droplet velocities agree well with experimental measurements but that droplet trajectory angles are overpredicted. Droplet sizes which are underpredicted by the model when collisions are neglected are still underpredicted when collisions are included although some improvement is noted.

  15. Differentiation of lisinopril and its RSS diastereomer by liquid chromatography combined with collision-induced dissociation mass spectrometry.

    PubMed

    Sun, Cuirong; Zhu, Peixi; Hu, Nan; Wang, Danhua; Pan, Yuanjiang

    2010-01-01

    A simple and sensitive liquid chromatography tandem multiple-stage mass spectrometry (HPLC/MS/MS) method suitable for bulk lisinopril analysis was developed, by which lisinopril and its RSS isomer were separated and differentiated. In the collision-induced dissociation (CID) mass spectra of the [M + H](+) ions, the abundance of the fragment ion of m/z 246 for lisinopril was about two times higher than the ion of m/z 245; however, the former fragment ion was noted to be a little lower than the latter for RSS isomer at all collision energies. In the CID mass spectra of the [M + Li](+) ion, the abundance of the rearrangement ion of m/z 315 for the RSS isomer was about three times higher than that for lisinopril. Furthermore, the difference was supported by the results of energy-resolved mass spectrometry (ERMS) in the test range of collision energies. Similar differences were also observed between the CID mass spectra of lisinopril and RSS isomer methylester, which indicated that the RSS isomer could be rapidly characterized by the CID mass spectra of both the protonated and lithium adduct ion. Elemental compositions of all the ions were confirmed by Fourier Transform ion cyclotron resonance ESI mass spectrometry (FT-ICR-ESI/MS). In addition, theoretical computations were carried out to support the experimental results. Copyright 2009 John Wiley & Sons, Ltd.

  16. 200 A GeV Au + Au collisions serve a nearly perfect quark-gluon liquid.

    PubMed

    Song, Huichao; Bass, Steffen A; Heinz, Ulrich; Hirano, Tetsufumi; Shen, Chun

    2011-05-13

    A new robust method to extract the specific shear viscosity (η/s)(QGP) of a quark-gluon plasma (QGP) at temperatures T(c) < T ≲ 2T(c) from the centrality dependence of the eccentricity-scaled elliptic flow v2/ε measured in ultrarelativistic heavy-ion collisions is presented. Coupling viscous fluid dynamics for the QGP with a microscopic transport model for hadronic freeze-out we find for 200 A GeV Au + Au collisions that v2/ε is a universal function of multiplicity density (1/S)(dN(ch)/dy) that depends only on the viscosity but not on the model used for computing the initial fireball eccentricity ε. Comparing with measurements we find 1<4π(η/s)(QGP) < 2.5 where the uncertainty range is dominated by model uncertainties for the values of ε used to normalize the measured v2.

  17. Collisions of sodium atoms with liquid glycerol: insights into solvation and ionization.

    PubMed

    Wiens, Justin P; Nathanson, Gilbert M; Alexander, William A; Minton, Timothy K; Lakshmi, Sankaran; Schatz, George C

    2014-02-26

    The reactive uptake and ionization of sodium atoms in glycerol were investigated by gas-liquid scattering experiments and ab initio molecular dynamics (AIMD) simulations. A nearly effusive beam of Na atoms at 670 K was directed at liquid glycerol in vacuum, and the scattered Na atoms were detected by a rotatable mass spectrometer. The Na velocity and angular distributions imply that all impinging Na atoms that thermally equilibrate on the surface remain behind, likely ionizing to e(-) and Na(+). The reactive uptake of Na atoms into glycerol was determined to be greater than 75%. Complementary AIMD simulations of Na striking a 17-molecule glycerol cluster indicate that the glycerol hydroxyl groups reorient around the Na atom as it makes contact with the cluster and begins to ionize. Although complete ionization did not occur during the 10 ps simulation, distinct correlations among the extent of ionization, separation between Na(+) and e(-), solvent coordination, and binding energies of the Na atom and electron were observed. The combination of experiments and simulations indicates that Na-atom deposition provides a low-energy pathway for generating solvated electrons in the near-interfacial region of protic liquids.

  18. Collision-induced dissociation of sulfur-containing imidazolium ionic liquids.

    PubMed

    Lesimple, Alain; He, Xun; Chan, Tak-Hang; Mamer, Orval

    2008-01-01

    A number of 1,2-dimethylimidazole ionic liquids substituted on N(II) with alkyl chains of varying lengths terminated with sulfur-containing groups were investigated by electrospray high-resolution tandem Fourier-transform mass spectrometry. Fragmentation pathways are strongly dependent on the oxidation state of the sulfur and the alkyl chain length. The dissociations detected are rationalized by deuterium labeling, comparisons between homologous compounds and accurate mass data. Several homolytic processes are reported, leading to distonic ions and loss of hydrogen, methyl and other free radicals.

  19. Gas-phase dissociation of ionic liquid aggregates studied by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation.

    PubMed

    Fernandes, Ana M; Coutinho, João A P; Marrucho, Isabel M

    2009-01-01

    Positive singly charged ionic liquid aggregates [(C(n)mim)(m+1)(BF(4))(m)](+) (mim = 3-methylimidazolium; n = 2, 4, 8 and 10) and [(C(4)mim)(m+1)(A)(m)](+) (A = Cl(-), BF(4) (-), PF(6) (-), CF(3)SO(3) (-) and (CF(3)SO(2))(2)N(-)) were investigated by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation. The electrospray ionisation mass spectra (ESI-MS) showed the formation of an aggregate with extra stability for m = 4 for all the ionic liquids with the exception of [C(4)mim][CF(3)SO(3)]. ESI-MS-MS and breakdown curves of aggregate ions showed that their dissociation occurred by loss of neutral species ([C(n)mim][A])(a) with a >or= 1. Variable-energy collision induced dissociation of each aggregate from m = 1 to m = 8 for all the ionic liquids studied enabled the determination of E(cm, 1/2) values, whose variation with m showed that the monomers were always kinetically much more stable than the larger aggregates, independently of the nature of cation and anion. The centre-of-mass energy values correlate well with literature data on ionic volumes and interaction and hydrogen bond energies.

  20. Recent research directions in Fribourg: nuclear dynamics in resonances revealed by 2-dimensional EEL spectra, electron collisions with ionic liquids and electronic excitation of pyrimidine

    NASA Astrophysics Data System (ADS)

    Allan, Michael; Regeta, Khrystyna; Gorfinkiel, Jimena D.; Mašín, Zdeněk; Grimme, Stefan; Bannwarth, Christoph

    2016-05-01

    The article briefly reviews three subjects recently investigated in Fribourg: (i) electron collisions with surfaces of ionic liquids, (ii) two-dimensional (2D) electron energy loss spectra and (iii) resonances in absolute cross sections for electronic excitation of unsaturated compounds. Electron energy loss spectra of four ionic liquids revealed a number of excited states, including triplet states. A solution of a dye in an ionic liquid showed an energy-loss band of the solute, but not in all ionic liquids. 2D spectra reveal state-to-state information (given resonance to given final state) and are shown to be an interesting means to gain insight into dynamics of nuclear motion in resonances. Absolute cross sections for pyrimidine are reported as a function of scattering angle and as a function of electron energy. They reveal resonant structure which was reproduced very nicely by R-matrix calculations. The calculation provided an assignment of the resonances which reveals common patterns in compounds containing double bonds.

  1. 200 A GeV Au+Au Collisions Serve a Nearly Perfect Quark-Gluon Liquid

    SciTech Connect

    Song Huichao; Bass, Steffen A.; Heinz, Ulrich; Shen, Chun; Hirano, Tetsufumi

    2011-05-13

    A new robust method to extract the specific shear viscosity ({eta}/s){sub QGP} of a quark-gluon plasma (QGP) at temperatures T{sub c}collisions is presented. Coupling viscous fluid dynamics for the QGP with a microscopic transport model for hadronic freeze-out we find for 200 A GeV Au+Au collisions that v{sub 2}/{epsilon} is a universal function of multiplicity density (1/S)(dN{sub ch}/dy) that depends only on the viscosity but not on the model used for computing the initial fireball eccentricity {epsilon}. Comparing with measurements we find 1<4{pi}({eta}/s){sub QGP}<2.5 where the uncertainty range is dominated by model uncertainties for the values of {epsilon} used to normalize the measured v{sub 2}.

  2. Freeze-out temperature and density in heavy-ion collisions at liquid-gas phase transition

    SciTech Connect

    Shlomo, Shalom

    2010-08-04

    The study of properties of hot nuclei and the search for liquid-gas phase transition in nuclei have been the subjects of many investigations in recent decades. We present a short and limited review of the theoretical and experimental status of determining the temperature and density of the disassembling nucleus from ratios of the yields of emitted fragments.

  3. Collision tectonics

    SciTech Connect

    Coward, M.P.; Ries, A.C.

    1985-01-01

    The motions of lithospheric plates have produced most existing mountain ranges, but structures produced as a result of, and following the collision of continental plates need to be distinguished from those produced before by subduction. If subduction is normally only stopped when collision occurs, then most geologically ancient fold belts must be collisional, so it is essential to recognize and understand the effects of the collision process. This book consists of papers that review collision tectonics, covering tectonics, structure, geochemistry, paleomagnetism, metamorphism, and magmatism.

  4. Quantum state-resolved molecular scattering of NO (2Π1 /2) at the gas-[Cnmim][Tf2N] room temperature ionic liquid interface: Dependence on alkyl chain length, collision energy, and temperature

    NASA Astrophysics Data System (ADS)

    Zutz, Amelia; Nesbitt, David J.

    2016-10-01

    Room temperature ionic liquids (RTILs) represent a promising class of chemically tunable, low vapor pressure solvents with myriad kinetic applications that depend sensitively on the nature of gas-molecule interactions at the liquid surface. This paper reports on rovibronically inelastic dynamics at the gas-RTIL interface, colliding supersonically cooled hyperthermal molecular beams of NO (1/2 2Π, N = 0) from 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (or [Cnmim][Tf2N]) and probing the scattered NO molecules via laser induced fluorescence (LIF) from the A(2Σ ) state. Specifically, inelastic energy transfer into NO rovibrational and electronic degrees of freedom is explored as a function of RTIL alkyl chain length (n), incident collision energy (Einc) and surface temperature (Ts). At low collision energies (Einc = 2.7(9) kcal/mol), the scattered NO molecules exhibit a rotational temperature (Trot) systematically colder than Ts for all chain lengths, which signals the presence of non-equilibrium dynamics in the desorption channel. At high collision energies (Einc = 20(2) kcal/mol), microscopic branching into trapping/desorption (TD) and impulsive scattering (IS) pathways is clearly evident, with the TD fraction (α ) exhibiting a step-like increase between short (n = 2, 4) and long (n = 8, 12, 16) alkyl chains consistent with theoretical predictions. For all hydrocarbon chain lengths and RTIL temperature conditions, NO rotational excitation in the IS channel yields hyperthermal albeit Boltzmann-like distributions well described by a "temperature" (TIS = 900 -1200 K) that decreases systematically with increasing n. Non-adiabatic, collision induced hopping between ground and excited spin-orbit states is found to be independent of RTIL alkyl chain length and yet increase with collision energy. The scattering data confirm previous experimental reports of an enhanced presence of the alkyl tail at the gas-RTIL interface with increasing n, as well as

  5. Galaxy collisions.

    NASA Astrophysics Data System (ADS)

    Struck, C.

    Theories of how galaxies, the fundamental constituents of large-scale structure, form and evolve have undergone a dramatic paradigm shift in the last few decades. Earlier views were of rapid, early collapse and formation of basic structures, followed by slow evolution of the stellar populations and steady buildup of the chemical elements. Current theories emphasize hierarchical buildup via recurrent collisions and mergers, separated by long periods of relaxation and secular restructuring. Thus, collisions between galaxies are now seen as a primary process in their evolution. This article begins with a brief history of how this once peripheral subject found its way to center stage. The author then tours parts of the vast array of collisional forms that have been discovered to date. Many examples are provided to illustrate how detailed numerical models and multiwaveband observations have allowed the general chronological sequence of collisional morphologies to be deciphered, and how these forms are produced by the processes of tidal kinematics, hypersonic gas dynamics, collective dynamical friction and violent relaxation. Galaxy collisions may trigger the formation of a large fraction of all the stars ever formed, and play a key role in fueling active galactic nuclei. Current understanding of the processes involved is reviewed. The last decade has seen exciting new discoveries about how collisions are orchestrated by their environment, how collisional processes depend on environment, and how these environments depend on redshift or cosmological time. These discoveries and prospects for the future are summarized in the final sections.

  6. Liquid chromatography coupled with ultraviolet absorbance detection, electrospray ionization, collision-induced dissociation and tandem mass spectrometry on a triple quadrupole for the on-line characterization of polyphenols and methylxanthines in green coffee beans.

    PubMed

    Alonso-Salces, Rosa Maria; Guillou, Claude; Berrueta, Luis A

    2009-02-01

    Liquid chromatography coupled with a photodiode array detector, electrospray ionization, collision-induced dissociation and tandem mass spectrometry (LC-DAD/ESI-CID-MS/MS) on a triple quadrupole (QqQ) has been used to detect and characterize polyphenols and methylxanthines in green coffee beans: three phenolic acids (caffeic acid, ferulic acid and dimethoxycinnamic acid), three isomeric caffeoylquinic acids (M(r) 354), three feruloylquinic acids (M(r) 368), one p-coumaroylquinic acid (M(r) 338), three dicaffeoylquinic acids (M(r) 516), three feruloyl-caffeoylquinic acids (M(r) 530), four p-coumaroyl-caffeoylquinic acids (M(r) 500), three diferuloylquinic acids (M(r) 544), six dimethoxycinnamoyl-caffeoylquinic acids (M(r) 544), three dimethoxycinnamoyl-feruloylquinic acids (M(r) 558), six cinnamoyl-amino acid conjugates, three cinnamoyl glycosides, and three methylxanthines (caffeine, theobromine and theophylline). Dimethoxycinnamic acid, three isomers of dimethoxycinnamoyl-caffeoylquinic acids and another three of dimethoxycinnamoyl-feruloylquinic acids, as well as the three cinnamoyl glycosides, had not previously been reported in coffee beans. Structures have been assigned on the basis of the complementary information obtained from UV-visible spectra, relative hydrophobicity, scan mode MS spectra, and fragmentation patterns in MS(2) spectra (both in the positive and negative ion modes) obtained using a QqQ at different collision energies. A structure diagnosis scheme is provided for the identification of different isomers of polyphenols and methylxanthines. Copyright 2009 John Wiley & Sons, Ltd.

  7. A simultaneous determination method for 5-fluorouracil and its metabolites in human plasma with linear range adjusted by in-source collision-induced dissociation using hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry.

    PubMed

    Ishii, Hideaki; Shimada, Miki; Yamaguchi, Hiroaki; Mano, Nariyasu

    2016-11-01

    We applied a new technique for quantitative linear range shift using in-source collision-induced dissociation (CID) to complex biological fluids to demonstrate its utility. The technique was used in a simultaneous quantitative determination method of 5-fluorouracil (5-FU), an anticancer drug for various solid tumors, and its metabolites in human plasma by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). To control adverse effects after administration of 5-FU, it is important to monitor the plasma concentration of 5-FU and its metabolites; however, no simultaneous determination method has yet been reported because of vastly different physical and chemical properties of compounds. We developed a new analytical method for simultaneously determining 5-FU and its metabolites in human plasma by LC/ESI-MS/MS coupled with the technique for quantitative linear range shift using in-source CID. Hydrophilic interaction liquid chromatography using a stationary phase with zwitterionic functional groups, phosphorylcholine, was suitable for separation of 5-FU from its nucleoside and interfering endogenous materials. The addition of glycerin into acetonitrile-rich eluent after LC separation improved the ESI-MS response of high polar analytes. Based on the validation results, linear range shifts by in-source CID is the reliable technique even with complex biological samples such as plasma. Copyright © 2016 John Wiley & Sons Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Reduction of in-source collision-induced dissociation and thermolysis of sulopenem prodrugs for quantitative liquid chromatography/electrospray ionization mass spectrometric analysis by promoting sodium adduct formation.

    PubMed

    Wujcik, Chad E; Kadar, Eugene P

    2008-10-01

    Six chromatographically resolved sulopenem prodrugs were monitored for their potential to undergo both in-source collision-induced dissociation (CID) and thermolysis. Initial Q1 scans for each prodrug revealed the formation of intense [Prodrug2 + H]+, [Prodrug2 + Na]+, [Prodrug + Na]+, and [Sulopenem + Na]+ ions. Non-adduct-associated sulopenem ([Sulopenem + H]+) along with several additional lower mass ions were also observed. Product ion scans of [Prodrug3 + Na]+ showed the retention of the sodium adduct in the collision cell continuing down to opening of the beta-lactam ring. In-source CID and temperature experiments were conducted under chromatographic conditions while monitoring several of the latter ion transitions (i.e., adducts, dimers and degradants/fragments) for a given prodrug. The resulting ion profiles indicated the regions of greatest stability for temperature and declustering potential (DP) that provided the highest signal intensity for each prodrug and minimized in-source degradation. The heightened stability of adduct ions, relative to their appropriate counterpart (i.e., dimer to dimer adduct and prodrug to prodrug adduct ions), was observed under elevated temperature and DP conditions. The addition of 100 microM sodium to the mobile phase further enhanced the formation of these more stable adduct ions, yielding an optimal [Prodrug + Na]+ ion signal at temperatures from 400 to 600 degrees C. A clinical liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay for sulopenem prodrug PF-04064900 in buffered whole blood was successfully validated using sodium-fortified mobile phase and the [PF-04064900 + Na]+ ion for quantitation. A conservative five-fold increase in sensitivity from previously validated preclinical assays using the [PF-04064900 + H]+ precursor ion was achieved.

  9. Part I: Microscopic description of liquid He II. Part II: Uniformly approximated WKB method as used for the calculation of phase shifts in heavy-ion collision problems

    SciTech Connect

    Suebka, P.

    1984-01-01

    In Part I, the excitation spectrum of liquid He II is obtained using the two-body potential consists of a hardcore potential plus an outside attractive potential. The sum of two gaussian potential of Khanna and Das which is similar to the Lennard-Jones potential is chosen as the attractive potential. The t-matrix method due to Brueckner and Sawada is adopted with modifications to replace the interaction potential. The spectrum gives the phonon branch and the roton dip which resemble the excitation spectrum for liquid He II. The temperature dependence of the excitation spectrum enters into calculation through the zero-momentum state occupation number. A better approximation of thermodynamic functions is obtained by extending Landau's theory to the situation where the excitation is a function of temperature as well as of momentum. Our thermodynamic calculations also bear qualitative agreement with measurements on He II as expected.

  10. Puck collisions

    NASA Astrophysics Data System (ADS)

    Hauge, E. H.

    2012-09-01

    Collisions between two ice hockey pucks sliding on frictionless ice are studied, with both inelasticity and frictional contact between the colliding surfaces of the two pucks taken into account. The latter couples translational and rotational motion. The full solution depends on the sign and magnitude of the initial mismatch between the surface velocities at the point of contact. The initial state defines two physically distinct regimes for the friction coefficient. To illustrate the complexities, we discuss at length the typical situation (well known from curling) when puck number 1 is initially at rest, and is hit by puck number 2 with an arbitrary impact parameter, velocity and angular velocity. We find that the total outgoing angle between the pucks exceeds \\frac{1}{2}\\pi if and only if the collision leads to a net increase in the translational part of the kinetic energy. The conditions for this to happen are scrutinized, and the results are presented both analytically and numerically by a set of representative curves. This paper is written with an ambitious undergraduate, and her teacher, in mind.

  11. 'All-in-one' analysis for metabolite identification using liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry with collision energy switching.

    PubMed

    Wrona, Mark; Mauriala, Timo; Bateman, Kevin P; Mortishire-Smith, Russell J; O'Connor, Desmond

    2005-01-01

    The removal of bottlenecks in discovery stage metabolite identification studies is an ongoing challenge for the pharmaceutical industry. We describe the use of an 'All-in-One' approach to metabolite characterization that leverages the fast scanning and high mass accuracy of hybrid quadrupole time-of-flight mass spectrometry (QqToFMS) instruments. Full-scan MS and MS/MS data is acquired using collision energy switching without the preselection, either manually or in a data-dependent manner, of precursor ions. The acquisition of 'clean' MS/MS data is assisted by the use of ultrahigh-performance chromatography. Data acquired using this method can then be mined post-acquisition in a number of ways. These include using narrow window extracted ion chromatograms (nwXICs) for expected biotransformations, XICs for the product ions of the parent compound and/or expected modification of these product ions, and neutral loss chromatograms. This approach has the potential to be truly comprehensive for the determination of in vitro biotransformations in a drug discovery environment.

  12. Probing lysine acetylation with a modification-specific marker ion using high-performance liquid chromatography/electrospray-mass spectrometry with collision-induced dissociation.

    PubMed

    Kim, Jin Young; Kim, Kyoung Wook; Kwon, Ho Jeong; Lee, Dai Woon; Yoo, Jong Shin

    2002-11-01

    Posttranslational acetylation of proteins regulates many diverse functions, including DNA recognition, protein-protein interaction, and protein stability. The identification of enzymes that regulate protein acetylation has revealed broader use of this modification than was previously suspected. In this study, we describe a method for identifying protein acetylation at lysine residues by analysis of digested protein using HPLC/ESI-MS with a new modification-specific marker ion. Collision-induced dissociation with capillary or nano-LC/ESI-TOF-MS was used to obtain a fragment ion useful as a marker for acetylated lysine. Although the acetylated lysine immonium ion at m/z 143.1 has been used as a marker ion for detecting acetylated lysine, it can be confused with internal fragment ion in some peptides, producing false positive results. We have found a novel marker ion at m/z 126.1, which is a further fragment ion induced by the loss of NH3 from the acetylated lysine immonium ions at m/z 143.1. This novel marker ion was found to be more specific and approximately 9 times more sensitive than the immonium ion at m/z 143.1. In addition, no interfering ions for acetylated peptides were found in the extracted ion chromatogram at m/z 126.1. The utility of this method was demonstrated with acetylated cytochrome c as a model compound. After the modification was probed by the new marker ion, the acetylated lysine site was determined by the CID-MS spectrum. This method was applied to identify histone H4 acetylation in HeLa cells treated with trichostatin A. Three protein bands separated by acid-urea-Triton gel electrophoresis were confirmed as tetra, tri, and diacetylated histone H4 at lysines 5, 8, 12, and 16. This method may be useful for assaying for lysine acetylation, which is an important regulatory process for a range of biological functions.

  13. Rapid determination of oxidized methionine residues in recombinant human basic fibroblast growth factor by ultra-performance liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry with in-source collision-induced dissociation.

    PubMed

    Ohkubo, Tsutomu; Inagaki, Shinsuke; Min, Jun Zhe; Kamiya, Daiki; Toyo'oka, Toshimasa

    2009-07-01

    The primary structure of the deteriorated recombinant human basic fibroblast growth factor (rhbFGF) was determined by ultra-performance liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) with in-source collision-induced dissociation (CID). The rhbFGFs before and after treatment with hydrogen peroxide (H(2)O(2)) were separated using an ACQUITY UPLC BEH300 C18 column (1.7 microm, 150 mm x 2.1 mm i.d.) with a gradient elution of a mixture of water/acetonitrile containing 0.1% formic acid. The separated proteins were then detected by a SYNAPT High Definition Mass Spectrometry system (SYNAPT-MS). Two methionine (Met) residues in the rhbFGF structure were oxidized to Met-sulfoxide (Met-O) in 0.03% H(2)O(2) at pH 2.0. As the result, three peaks, except for the peak of rhbFGF, appeared on the chromatogram. The three proteins corresponding to each peak were estimated as the denatured rhbFGFs including the Met-O residue(s) with TOF-MS. Furthermore, the position of the Met-O residue(s) was efficiently identified by UPLC/ESI-QTOF-MS using the in-source CID technique. The proposed method seems to be very useful for the structural elucidation of proteins, because the oxidized Met residues in rhbFGF were easily and rapidly identified.

  14. Online immunoaffinity liquid chromatography/tandem mass spectrometry determination of a type II collagen peptide biomarker in rat urine: Investigation of the impact of collision-induced dissociation fluctuation on peptide quantitation.

    PubMed

    Berna, Michael; Schmalz, Chris; Duffin, Kevin; Mitchell, Peter; Chambers, Mark; Ackermann, Brad

    2006-09-15

    Proteolytic fragments of type II collagen, a major component of joint tissue, have recently been identified as biomarkers for osteoarthritis, a progressive disease associated with cartilage degeneration. A liquid chromatography/tandem mass spectrometry (MS/MS) assay that utilizes online immunoaffinity chromatography and column switching was developed in our laboratory for the neoepitope of type II collagen (NET2C). During method development, peptide collision-induced dissociation (CID) was found to be a significant source of assay variation, which exceeded 10% CV, despite the fact that a stable-isotope-labeled (SIL) internal standard was used to minimize imprecision. This phenomenon was studied in detail using peptides and associated SIL internal standards of varying lengths and amino acid compositions. Variability in peptide CID necessitated the monitoring of multiple MS/MS transitions to obtain acceptable assay precision. The assay was subsequently validated to measure NET2C concentrations in rat urine over the range of 0.1 to 10 ng/mL. The interday accuracy and precision ranged from 3.9 to 13.1 (%CV) and 10.7 to 5.3 (%RE), respectively, across the range of validated concentrations. A specific application of the assay is presented in which the role of estrogen deficiency in the development and progression of osteoarthritis was investigated. In this study, the effect of estrogen on lowering NET2C concentrations in urine in ovariectomized rats was demonstrated.

  15. RHIC The Perfect Liquid

    ScienceCinema

    BNL

    2016-07-12

    Evidence to date suggests that gold-gold collisions the Relativistic Heavy Ion Collider at Brookhaven are indeed creating a new state of hot, dense matter, but one quite different and even more remarkable than had been predicted. Instead of behaving like a gas of free quarks and gluons, as was expected, the matter created in RHIC's heavy ion collisions appears to be more like a "perfect" liquid.

  16. RHIC The Perfect Liquid

    SciTech Connect

    BNL

    2008-08-12

    Evidence to date suggests that gold-gold collisions the Relativistic Heavy Ion Collider at Brookhaven are indeed creating a new state of hot, dense matter, but one quite different and even more remarkable than had been predicted. Instead of behaving like a gas of free quarks and gluons, as was expected, the matter created in RHIC's heavy ion collisions appears to be more like a "perfect" liquid.

  17. Stability and Degradation of Caffeoylquinic Acids under Different Storage Conditions Studied by High-Performance Liquid Chromatography with Photo Diode Array Detection and High-Performance Liquid Chromatography with Electrospray Ionization Collision-Induced Dissociation Tandem Mass Spectrometry.

    PubMed

    Xue, Meng; Shi, Hang; Zhang, Jiao; Liu, Qing-Quan; Guan, Jun; Zhang, Jia-Yu; Ma, Qun

    2016-07-21

    Caffeoylquinic acids (CQAs) are main constituents in many herbal medicines with various biological and pharmacological effects. However, CQAs will degrade or isomerize when affected by temperature, pH, light, etc. In this study, high-performance liquid chromatography with photodiode array detection (HPLC-PDA) and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was utilized to study the stability and degradation of CQAs (three mono-acyl CQAs and four di-acyl CQAs) under various ordinary storage conditions (involving different temperatures, solvents, and light irradiation). The results indicated that the stability of CQAs was mainly affected by temperature and light irradiation, while solvents did not affect it in any obvious way under the conditions studied. Mono-acyl CQAs were generally much more stable than di-acyl CQAs under the same conditions. Meanwhile, the chemical structures of 30 degradation products were also characterized by HPLC-MS(n), inferring that isomerization, methylation, and hydrolysis were three major degradation pathways. The result provides a meaningful clue for the storage conditions of CQAs standard substances and samples.

  18. Direct comparison of capillary electrophoresis and capillary liquid chromatography hyphenated to collision-cell inductively coupled plasma mass spectrometry for the investigation of Cd-, Cu- and Zn-containing metalloproteins.

    PubMed

    Montes-Bayon, Maria; Pröfrock, Daniel; Sanz-Medel, Alfredo; Prange, Andreas

    2006-05-05

    Capillary liquid chromatography (cLC) and capillary electrophoresis (CE) have been critically compared for the separation of metalloproteins when using collision-cell inductively coupled plasma mass spectrometry (ICP-CC-MS) as detection system. For cLC separation, the selected column was a C8 (0.3 mm I.D.) and the separation conditions involved a gradient up to 80% methanol in 10mM ammonium acetate buffer (pH 7.4). The low flow rate used (3 microL min(-1)) permitted the utilization of a high methanol content maintaining the sensitivity along the whole chromatographic run. For this purpose, a new low-flow interface has been developed based on a total consumption nebulizer. Similarly, CE has been studied as separation technique using a 75 microm I.D. fused silica capillary and a running buffer of 20 mM Tris-HNO3 (pH 7.4) and working at 30 kV. Metallothionein (mixture of MT-I and -II) and superoxide dismutase (SOD) have been used as protein models in order to evaluate the separation/detection capabilities using the same injection volumes in both systems (20 nL). For both hybrid systems, separation parameters such as retention factor, numbers of theoretical plates, tailing factor and resolution have been critically compared. Also, the analytical performance characteristics of both hybrid systems have been evaluated and tested by analyzing the Cu-, Zn-species present in red blood cell extracts in order to explore more adequate separation methodology for the analysis of metalloproteins in complex matrices.

  19. Electron collisions with the HCOOH⋯(H2O)n complexes (n = 1, 2) in liquid phase: The influence of microsolvation on the π* resonance of formic acid

    NASA Astrophysics Data System (ADS)

    Freitas, T. C.; Coutinho, K.; Varella, M. T. do N.; Lima, M. A. P.; Canuto, S.; Bettega, M. H. F.

    2013-05-01

    We report momentum transfer cross sections for elastic collisions of low-energy electrons with the HCOOH⋯(H2O)n complexes, with n = 1, 2, in liquid phase. The scattering cross sections were computed using the Schwinger multichannel method with pseudopotentials in the static-exchange and static-exchange plus polarization approximations, for energies ranging from 0.5 eV to 6 eV. We considered ten different structures of HCOOH⋯H2O and six structures of HCOOH⋯(H2O)2 which were generated using classical Monte Carlo simulations of formic acid in aqueous solution at normal conditions of temperature and pressure. The aim of this work is to investigate the influence of microsolvation on the π* shape resonance of formic acid. Previous theoretical and experimental studies reported a π* shape resonance for HCOOH at around 1.9 eV. This resonance can be either more stable or less stable in comparison to the isolated molecule depending on the complex structure and the water role played in the hydrogen bond interaction. This behavior is explained in terms of (i) the polarization of the formic acid molecule due to the water molecules and (ii) the net charge of the solute. The proton donor or acceptor character of the water molecules in the hydrogen bond is important for understanding the stabilization versus destabilization of the π* resonances in the complexes. Our results indicate that the surrounding water molecules may affect the lifetime of the π* resonance and hence the processes driven by this anion state, such as the dissociative electron attachment.

  20. Collision Repair Campaign

    EPA Pesticide Factsheets

    The Collision Repair Campaign targets meaningful risk reduction in the Collision Repair source category to reduce air toxic emissions in their communities. The Campaign also helps shops to work towards early compliance with the Auto Body Rule.

  1. Probability of satellite collision

    NASA Technical Reports Server (NTRS)

    Mccarter, J. W.

    1972-01-01

    A method is presented for computing the probability of a collision between a particular artificial earth satellite and any one of the total population of earth satellites. The collision hazard incurred by the proposed modular Space Station is assessed using the technique presented. The results of a parametric study to determine what type of satellite orbits produce the greatest contribution to the total collision probability are presented. Collision probability for the Space Station is given as a function of Space Station altitude and inclination. Collision probability was also parameterized over miss distance and mission duration.

  2. Global Λ hyperon polarization in nuclear collisions

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bunzarov, I.; Butterworth, J.; Caines, H.; de La Barca Sánchez, M. Calderón; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; de Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, X.; Huang, H. Z.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kocmanek, M.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, L.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, W.; Li, Y.; Lidrych, J.; Lin, T.; Lisa, M. A.; Liu, H.; Liu, P.; Liu, Y.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, S.; Luo, X.; Ma, G. L.; Ma, L.; Ma, Y. G.; Ma, R.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Rehbein, M. J.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roth, J. D.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Saur, M.; Schambach, J.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seger, J.; Sergeeva, M.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Strikhanov, M.; Stringfellow, B.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; van Buren, G.; van Nieuwenhuizen, G.; Vasiliev, A. N.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, Y.; Wang, F.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y. F.; Xu, Z.; Yang, Y.; Yang, Q.; Yang, C.; Yang, S.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Z.; Zhang, X. P.; Zhang, J. B.; Zhang, S.; Zhang, J.; Zhang, Y.; Zhang, J.; Zhang, S.; Zhao, J.; Zhong, C.; Zhou, L.; Zhou, C.; Zhu, X.; Zhu, Z.; Zyzak, M.

    2017-08-01

    The extreme energy densities generated by ultra-relativistic collisions between heavy atomic nuclei produce a state of matter that behaves surprisingly like a fluid, with exceptionally high temperature and low viscosity. Non-central collisions have angular momenta of the order of 1,000ћ, and the resulting fluid may have a strong vortical structure that must be understood to describe the fluid properly. The vortical structure is also of particular interest because the restoration of fundamental symmetries of quantum chromodynamics is expected to produce novel physical effects in the presence of strong vorticity. However, no experimental indications of fluid vorticity in heavy ion collisions have yet been found. Since vorticity represents a local rotational structure of the fluid, spin-orbit coupling can lead to preferential orientation of particle spins along the direction of rotation. Here we present measurements of an alignment between the global angular momentum of a non-central collision and the spin of emitted particles (in this case the collision occurs between gold nuclei and produces Λ baryons), revealing that the fluid produced in heavy ion collisions is the most vortical system so far observed. (At high energies, this fluid is a quark-gluon plasma.) We find that Λ and hyperons show a positive polarization of the order of a few per cent, consistent with some hydrodynamic predictions. (A hyperon is a particle composed of three quarks, at least one of which is a strange quark; the remainder are up and down quarks, found in protons and neutrons.) A previous measurement that reported a null result, that is, zero polarization, at higher collision energies is seen to be consistent with the trend of our observations, though with larger statistical uncertainties. These data provide experimental access to the vortical structure of the nearly ideal liquid created in a heavy ion collision and should prove valuable in the development of hydrodynamic models that

  3. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  4. Ball Collision Experiments

    ERIC Educational Resources Information Center

    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.

  5. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  6. Ball Collision Experiments

    ERIC Educational Resources Information Center

    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.

  7. Bubble collision with gravitation

    SciTech Connect

    Hwang, Dong-il; Lee, Bum-Hoon; Lee, Wonwoo; Yeom, Dong-han E-mail: bhl@sogang.ac.kr E-mail: innocent.yeom@gmail.com

    2012-07-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  8. Effects of hydrogen atom spin exchange collisions on atomic hydrogen maser oscillation frequency

    NASA Technical Reports Server (NTRS)

    Crampton, S. B.

    1979-01-01

    Frequency shifts due to collisions between hydrogen atoms in an atomic hydrogen maser frequency standard are studied. Investigations of frequency shifts proportional to the spin exchange frequency shift cross section and those proportional to the duration of exchange collisions are discussed. The feasibility of operating a hydrogen frequency standard at liquid helium temperatures is examined.

  9. Asteroidal collision probabilities

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Greenberg, R.

    1993-05-01

    Several past calculations of collision probabilities between pairs of bodies on independent orbits have yielded inconsistent results. We review the methodologies and identify their various problems. Greenberg's (1982) collision probability formalism (now with a corrected symmetry assumption) is equivalent to Wetherill's (1967) approach, except that it includes a way to avoid singularities near apsides. That method shows that the procedure by Namiki and Binzel (1991) was accurate for those cases where singularities did not arise.

  10. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  11. Launch Collision Probability

    NASA Technical Reports Server (NTRS)

    Bollenbacher, Gary; Guptill, James D.

    1999-01-01

    This report analyzes the probability of a launch vehicle colliding with one of the nearly 10,000 tracked objects orbiting the Earth, given that an object on a near-collision course with the launch vehicle has been identified. Knowledge of the probability of collision throughout the launch window can be used to avoid launching at times when the probability of collision is unacceptably high. The analysis in this report assumes that the positions of the orbiting objects and the launch vehicle can be predicted as a function of time and therefore that any tracked object which comes close to the launch vehicle can be identified. The analysis further assumes that the position uncertainty of the launch vehicle and the approaching space object can be described with position covariance matrices. With these and some additional simplifying assumptions, a closed-form solution is developed using two approaches. The solution shows that the probability of collision is a function of position uncertainties, the size of the two potentially colliding objects, and the nominal separation distance at the point of closest approach. ne impact of the simplifying assumptions on the accuracy of the final result is assessed and the application of the results to the Cassini mission, launched in October 1997, is described. Other factors that affect the probability of collision are also discussed. Finally, the report offers alternative approaches that can be used to evaluate the probability of collision.

  12. Visually guided collision avoidance and collision achievement.

    PubMed

    Regan; Gray

    2000-03-01

    To survive on today's highways, a driver must have highly developed skills in visually guided collision avoidance. To play such games as cricket, tennis or baseball demands accurate, precise and reliable collision achievement. This review discusses evidence that some of these tasks are performed by predicting where an object will be at some sharply defined instant, several hundred milliseconds in the future, while other tasks are performed by utilizing the fact that some of our motor actions change what we see in ways that obey lawful relationships, and can therefore be learned. Several monocular and binocular visual correlates of the direction of an object's motion relative to the observer's head have been derived theoretically, along with visual correlates of the time to collision with an approaching object. Although laboratory psychophysics can identify putative neural mechanisms by showing which of the known correlates are processed by the human visual system independently of other visual information, it is only field research on, for example, driving, aviation and sport that can show which visual cues are actually used in these activities. This article reviews this research and describes a general psychophysically based rational approach to the design of such field studies.

  13. Binary droplet collision at high Weber number

    NASA Astrophysics Data System (ADS)

    Pan, Kuo-Long; Chou, Ping-Chung; Tseng, Yu-Jen

    2009-09-01

    By using the techniques developed for generating high-speed droplets, we have systematically investigated binary droplet collision when the Weber number (We) was increased from the range usually tested in previous studies on the order of 10 to a much larger value of about 5100 for water (a droplet at 23 m/s with a diameter of 0.7 mm). Various liquids were also used to explore the effects of viscosity and surface tension. Specifically, beyond the well-known regimes at moderate We’s, which exhibited coalescence, separation, and separation followed by satellite droplets, we found different behaviors showing a fingering lamella, separation after fingering, breakup of outer fingers, and prompt splattering into multiple secondary droplets as We was increased. The critical Weber numbers that mark the boundaries between these impact regimes are identified. The specific impact behaviors, such as fingering and prompt splattering or splashing, share essential similarity with those also observed in droplet-surface impacts, whereas substantial variations in the transition boundaries may result from the disparity of the boundary conditions at impacts. To compare the outcomes of both types of collisions, a simple model based on energy conservation was carried out to predict the maximum diameter of an expanding liquid disk for a binary droplet collision. The results oppose the dominance of viscous drag, as proposed by previous studies, as the main deceleration force to effect a Rayleigh-Taylor instability and ensuing periphery fingers, which may further lead to the formations of satellite droplets.

  14. Analyzing cosmic bubble collisions

    SciTech Connect

    Gobbetti, Roberto; Kleban, Matthew E-mail: mk161@nyu.edu

    2012-05-01

    We develop a set of controlled, analytic approximations to study the effects of bubble collisions on cosmology. We expand the initial perturbation to the inflaton field caused by the collision in a general power series, and determine its time evolution during inflation in terms of the coefficients in the expansion. In models where the observer's bubble undergoes sufficient slow-roll inflation to solve the flatness problem, in the thin wall limit only one coefficient in the expansion is relevant to observational cosmology, allowing nearly model-independent predictions. We discuss two approaches to determining the initial perturbation to the inflaton and the implications for the sign of the effect (a hot or cold spot on the Cosmic Microwave Background temperature map). Lastly, we analyze the effects of collisions with thick-wall bubbles, i.e. away from the thin-wall limit.

  15. Microscope collision protection apparatus

    DOEpatents

    DeNure, Charles R.

    2001-10-23

    A microscope collision protection apparatus for a remote control microscope which protects the optical and associated components from damage in the event of an uncontrolled collision with a specimen, regardless of the specimen size or shape. In a preferred embodiment, the apparatus includes a counterbalanced slide for mounting the microscope's optical components. This slide replaces the rigid mounts on conventional upright microscopes with a precision ball bearing slide. As the specimen contacts an optical component, the contacting force will move the slide and the optical components mounted thereon. This movement will protect the optical and associated components from damage as the movement causes a limit switch to be actuated, thereby stopping all motors responsible for the collision.

  16. Collision of cosmic superstrings

    SciTech Connect

    Copeland, E. J.; Firouzjahi, H.; Kibble, T. W. B.; Steer, D. A.

    2008-03-15

    We study the formation of three-string junctions between (p,q)-cosmic superstrings, and collisions between such strings and show that kinematic constraints analogous to those found previously for collisions of Nambu-Goto strings apply here too, with suitable modifications to take account of the additional requirements of flux conservation. We examine in detail several examples involving collisions between strings with low values of p and q, and also examine the rates of growth or shrinkage of strings at a junction. Finally, we briefly discuss the formation of junctions for strings in a warped space, specifically with a Klebanov-Strassler throat, and show that similar constraints still apply with changes to the parameters taking account of the warping and the background flux.

  17. About the Collision Repair Campaign

    EPA Pesticide Factsheets

    EPA developed the Collision Repair Campaign to focus on meaningful risk reduction in the Collision Repair source sector to complement ongoing community air toxics work and attain reductions at a faster rate.

  18. Atomic cluster collisions

    NASA Astrophysics Data System (ADS)

    Korol, Andrey V.; Solov'yov, Andrey

    2013-01-01

    Atomic cluster collisions are a field of rapidly emerging research interest by both experimentalists and theorists. The international symposium on atomic cluster collisions (ISSAC) is the premier forum to present cutting-edge research in this field. It was established in 2003 and the most recent conference was held in Berlin, Germany in July of 2011. This Topical Issue presents original research results from some of the participants, who attended this conference. This issues specifically focuses on two research areas, namely Clusters and Fullerenes in External Fields and Nanoscale Insights in Radiation Biodamage.

  19. Ice particle collisions

    NASA Astrophysics Data System (ADS)

    Sampara, Naresh; Turnbull, Barbara; Hill, Richard; Swift, Michael

    2017-04-01

    Granular interactions of ice occur in a range of geophysical, astrophysical and industrial applications. For example, Saturn's Rings are composed of icy particles from micrometers to kilometres in size - inertial and yet too small to interact gravitationally. In clouds, ice crystals are smashed to pieces before they re-aggregate to for snow floccules in a process that is very much open to interpretation. In a granular flow of ice particles, the energy spent in collisions can lead to localized surface changes and wetting, which in turn can promote aggregation. To understand the induced wetting and its effects, we present two novel experimental methods which provide snippets of insight into the collisional behaviour of macroscopic ice particles. Experiment 1: Microgravity experiments provide minute details of the contact between the ice particles during the collision. A diamagnetic levitation technique, as alternative to the parabolic flight or falling tower experiments, was used to understand the collisional behaviour of individual macroscopic icy bodies. A refrigerated cylinder, that can control ambient conditions, was inserted into the bore of an 18 Tesla superconducting magnet and cooled to -10°C. Initial binary collisions were created, where one 4 mm ice particle was levitated in the magnet bore whilst another particle was dropped vertically from the top of the bore. The trajectories of both particles were captured by high speed video to provide the three-dimensional particle velocities and track the collision outcome. Introducing complexity, multiple particles were levitated in the bore and an azimuthal turbulent air flow introduced, allowing the particles to collide with other particles within a coherent fluid structure (mimicking Saturn's rings, or an eddy in a cloud). In these experiments, a sequence of collisions occur, each one different to the previous one due to the changes in surface characteristics created by the collisions themselves. Aggregation

  20. Spacecraft Collision Avoidance

    NASA Astrophysics Data System (ADS)

    Bussy-Virat, Charles

    The rapid increase of the number of objects in orbit around the Earth poses a serious threat to operational spacecraft and astronauts. In order to effectively avoid collisions, mission operators need to assess the risk of collision between the satellite and any other object whose orbit is likely to approach its trajectory. Several algorithms predict the probability of collision but have limitations that impair the accuracy of the prediction. An important limitation is that uncertainties in the atmospheric density are usually not taken into account in the propagation of the covariance matrix from current epoch to closest approach time. The Spacecraft Orbital Characterization Kit (SpOCK) was developed to accurately predict the positions and velocities of spacecraft. The central capability of SpOCK is a high accuracy numerical propagator of spacecraft orbits and computations of ancillary parameters. The numerical integration uses a comprehensive modeling of the dynamics of spacecraft in orbit that includes all the perturbing forces that a spacecraft is subject to in orbit. In particular, the atmospheric density is modeled by thermospheric models to allow for an accurate representation of the atmospheric drag. SpOCK predicts the probability of collision between two orbiting objects taking into account the uncertainties in the atmospheric density. Monte Carlo procedures are used to perturb the initial position and velocity of the primary and secondary spacecraft from their covariance matrices. Developed in C, SpOCK supports parallelism to quickly assess the risk of collision so it can be used operationally in real time. The upper atmosphere of the Earth is strongly driven by the solar activity. In particular, abrupt transitions from slow to fast solar wind cause important disturbances of the atmospheric density, hence of the drag acceleration that spacecraft are subject to. The Probability Distribution Function (PDF) model was developed to predict the solar wind speed

  1. Multiplicity distributions in nuclear collisions

    SciTech Connect

    Capella, A.; Casado, J.A.; Pajares, C.; Ramallo, A.V.; Tran Tranh Van, J.

    1987-05-01

    Multiplicity distributions in nuclear collisions are calculated in the framework of the dual parton model. A comparison with experimental data is performed. The multiplicity distributions for /sup 16/O-/sup 207/Pb collisions at 200 Gev/c per nucleon is predicted. The fluctuations of the energy density in the central rapidity region for such collisions are estimated.

  2. Simulation of Droplets Collisions Using Two-Phase Entropic Lattice Boltzmann Method

    NASA Astrophysics Data System (ADS)

    Mazloomi Moqaddam, A.; Chikatamarla, S. S.; Karlin, I. V.

    2015-12-01

    The recently introduced entropic lattice Boltzmann model for multiphase flows (Mazloomi et al. in Phys Rev Lett 114:174502, 2015) is used to simulate binary droplet collisions. The entropy-based stabilization, together with a new polynomial equation of state, enhances performance of the model and allow us to simulate droplet collision for various Weber and Reynolds numbers and large liquid to vapor density ratio. Different types of droplet collision outcomes, namely coalescence, stretching separation and reflexive separation are recovered in a range of impact parameter for two equal sized droplets. The results demonstrated the essential role played by the surface tension, kinematic viscosity, impact parameter and relative velocity in the droplet collision dynamics leading to coalescence or separation collision outcomes. Comparison between numerical results and experiments in both coalescence and separation collisions demonstrate viability of the presented model.

  3. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  4. Space collision threat mitigation

    NASA Astrophysics Data System (ADS)

    Zatezalo, Aleksandar; Stipanović, Dušan; Mehra, Raman K.; Pham, Khanh

    2014-06-01

    Mitigation of possible collision threats to current and future operations in space environments is an important an challenging task considering high nonlinearity of orbital dynamics and discrete measurement updates. Such discrete observations are relatively scarce with respect to space dynamics including possible unintentional or intentional rocket propulsion based maneuvers even in scenarios when measurement collections are focused to a one single target of interest. In our paper, this problem is addressed in terms of multihypothesis and multimodel estimation in conjunction with multi-agent multigoal game theoretic guaranteed evasion strategies. Collision threat estimation is formulated using conditional probabilities of time dependent hypotheses and spacecraft controls which are computed using Liapunov-like approach. Based on this formulation, time dependent functional forms of multi-objective utility functions are derived given threat collision risk levels. For demonstrating developed concepts, numerical methods are developed using nonlinear filtering methodology for updating hypothesis sets and corresponding conditional probabilities. Space platform associated sensor resources are managed using previously developed and demonstrated information-theoretic objective functions and optimization methods. Consequently, estimation and numerical methods are evaluated and demonstrated on a realistic Low Earth Orbit collision encounter.

  5. Neutrino-atom collisions

    NASA Astrophysics Data System (ADS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2016-05-01

    Neutrino-atom scattering provides a sensitive tool for probing nonstandard interactions of massive neutrinos in laboratory measurements. The ionization channel of this collision process plays an important role in experiments searching for neutrino magnetic moments. We discuss some theoretical aspects of atomic ionization by massive neutrinos. We also outline possible manifestations of neutrino electromagnetic properties in coherent elastic neutrino-nucleus scattering.

  6. Collision avoidance in space

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.; Cour-Palais, B. G.; Taylor, R. E.; Landry, P. M.

    1980-01-01

    Collisions in earth orbital space between operational payloads and various forms of space debris (nonoperational payloads, nonfunctional mission-related objects and fragments resulting from collisions and explosions) are discussed and possible means of avoiding them are considered. From 10,000 to 15,000 objects are estimated to be in earth orbital space, most of which represent spacecraft fragments and debris too small to be detected and tracked by earth-based sensors, and it is considered likely that some of them will be or have already been involved in direct collisions with the ever increasing number of operational satellites and space stations. Means of protecting proposed large space structures and smaller spacecraft from significant damage by larger space objects, particularly in the 400-4000 km altitude range where most debris occurs, include structural redundancy and the double shielding of sensitive components. Other means of collision avoidance are the collection or relocation of satellites, rocket bodies and other objects by the Space Shuttle, the prevention of explosions and the disposal of spent rocket parts by reentry. Finally, a management structure would be required to administer guidelines for the prevention and elimination of space debris.

  7. Atomic collisions, inelastic indeed

    NASA Astrophysics Data System (ADS)

    Bercegol, Herve; Ferrando, Gwenael; Lehoucq, Roland

    At the turn of the twentieth century, a hot controversy raged about the ability of Boltzmann's framework to take care of irreversibility. The so-called Loschmidt's paradox progressively faded with time during the last hundred years, due to the predictive efficiency of statistical mechanics. However, one detail at the origin of the controversy - the elasticity of atomic collisions - was not completely challenged. A semi-classical treatment of two atoms interacting with the vacuum zero-point field permits to predict a friction force acting against the rotation of the pair of atoms. By its form and its level, the calculated torque is a candidate as a physical cause for diffusion of energy and angular momentum, and consequently for entropy growth. It opens the way to a revision of the standard vision of irreversibility. This presentation will focus on two points. First we will discuss the recent result in a broader context of electromagnetic interactions during microscopic collisions. The predicted friction phenomenon can be compared to and distinguished from Collision-Induced Emission and other types of inelastic collisions. Second we will investigate the consequences of the friction torque on calculated trajectories of colliding atoms, quantifying the generation of dimers linked by dispersion forces.

  8. Surface impacts and collisions of particle-laden nanodrops

    NASA Astrophysics Data System (ADS)

    Koplik, Joel

    2015-08-01

    The surface impact and collisions of particle-laden nanodrops are studied using molecular dynamics computer simulations. The drops are composed of Lennard-Jones dimers and the particles are rigid spherical sections of a cubic lattice, with radii about 11 nm and 0.6 nm, respectively. Uniform suspensions of 21% and 42% particle concentrations and particle-coated drops are studied, and their behavior is compared to that of pure fluid drops of the same size. The relative velocities studied span the transition to splashing, and both wetting/miscible and non-wetting/immiscible cases are considered. Impacts normal to the surface and head-on collisions are studied and compared. In surface impact, the behavior of low-density suspensions and liquid marble drops is qualitatively similar to that of pure liquid, while the concentrated drops are solid-like on impact. Collisions produce a splash only at velocities significantly higher than in impact, but the resulting drop morphology shows a similar dependence on solid concentration as in impact. In all cases, the collision or impact produces a strong local enhancement in the kinetic energy density and temperature but not in the particle or potential energy densities. Mixing of the two colliding species is not enhanced by collisions, unless the velocity is so high as to cause drop disintegration.

  9. Comprehensive analysis of a multidimensional liquid chromatography mass spectrometry dataset acquired on a quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometer: I. How much of the data is theoretically interpretable by search engines?

    PubMed

    Chalkley, Robert J; Baker, Peter R; Hansen, Kirk C; Medzihradszky, Katalin F; Allen, Nadia P; Rexach, Michael; Burlingame, Alma L

    2005-08-01

    An in-depth analysis of a multidimensional chromatography-mass spectrometry dataset acquired on a quadrupole selecting, quadrupole collision cell, time-of-flight (QqTOF) geometry instrument was carried out. A total of 3269 CID spectra were acquired. Through manual verification of database search results and de novo interpretation of spectra 2368 spectra could be confidently determined as predicted tryptic peptides. A detailed analysis of the non-matching spectra was also carried out, highlighting what the non-matching spectra in a database search typically are composed of. The results of this comprehensive dataset study demonstrate that QqTOF instruments produce information-rich data of which a high percentage of the data is readily interpretable.

  10. Ultrasensitive characterization of site-specific glycosylation of affinity-purified haptoglobin from lung cancer patient plasma using 10 μm i.d. porous layer open tubular liquid chromatography-linear ion trap collision-induced dissociation/electron transfer dissociation mass spectrometry.

    PubMed

    Wang, Dongdong; Hincapie, Marina; Rejtar, Tomas; Karger, Barry L

    2011-03-15

    Site-specific analysis of protein glycosylation is important for biochemical and clinical research efforts. Glycopeptide analysis using liquid chromatography-collision-induced dissociation/electron transfer dissociation mass spectrometry (LC-CID/ETD-MS) allows simultaneous characterization of the glycan structure and attached peptide site. However, due to the low ionization efficiency of glycopeptides during electrospray ionization, 200-500 fmol of sample per injection is needed for a single LC-MS run, which makes it challenging for the analysis of limited amounts of glycoprotein purified from biological matrixes. To improve the sensitivity of LC-MS analysis for glycopeptides, an ultranarrow porous layer open tubular (PLOT) LC column (2.5 m × 10 μm i.d.) was coupled to a linear ion trap (LTQ) collision-induced dissociation/electron transfer dissociation mass spectrometer to provide sensitive analysis of N-linked protein glycosylation heterogeneity. The potential of the developed method is demonstrated by the characterization of site-specific glycosylation using haptoglobin (Hpt) as a model protein. To limit the amount of haptoglobin to low picomole amounts of protein, we affinity purified it from 1 μL of pooled lung cancer patient plasma. A total of 26 glycoforms/glycan compositions on three Hpt tryptic glycopeptides were identified and quantified from 10 LC-MS runs with a consumption of 100 fmol of Hpt digest (13 ng of protein, 10 fmol per injection). Included in this analysis was the determination of the glycan occupancy level. At this sample consumption level, the high sensitivity of the PLOT LC-LTQ-CID/ETD-MS system allowed glycopeptide identification and structure determination, along with relative quantitation of glycans presented on the same peptide backbone, even for low abundant glycopeptides at the ∼100 amol level. The PLOT LC-MS system is shown to have sufficient sensitivity to allow characterization of site-specific protein glycosylation from trace

  11. Reactive Collision Avoidance Algorithm

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

    2010-01-01

    The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on

  12. Liquid Argon Calorimetry for ATLAS

    NASA Astrophysics Data System (ADS)

    Robinson, Alan

    2008-05-01

    This summer, the largest collaborative physics project since the Manhattan project will go online. One of four experiments for the Large Hadron Collider at CERN in Geneva, ATLAS, employs over 2000 people. Canadians have helped design, construct, and calibrate the liquid argon calorimeters for ATLAS to capture the products of the high energy collisions produced by the LHC. From an undergraduate's perspective, explore how these calorimeters are made to handle their harsh requirement. From nearly a billion proton-proton collisions a second, physicists hope to discover the Higgs boson and other new fundamental particles.

  13. Collision Avoidance System

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Ames Research Center teamed with the Federal Aviation Administration (FAA) to study human performance factors associated with the use of the Traffic Alert and Collision Avoidance system (TCAS II) in an operational environment. TCAS is designed to alert pilots of the presence of other aircraft in their vicinity, to identify and track those who could be a threat, and to recommend action to avoid a collision. Ames conducted three laboratory experiments. The first showed that pilots were able to use the TCAS II correctly in the allowable time. The second tested pilots' response to changes in the avoidance advisories, and the third examined pilots' reactions to alternative displays. After a 1989 congressional mandate, the FAA ruled that TCAS would be required on all passenger carrying aircraft (to be phased in completely by 1995).

  14. Micro UAV collision avoidance

    NASA Astrophysics Data System (ADS)

    Merchant, John; Pope, Frank

    2007-04-01

    A range image for micro UAV (unmanned air vehicle) collision avoidance is derived by processing a sequence of conventional images from a single camera on board the UAV. The range image will warn of looming collisions immediately ahead and also provide the 3-D situational awareness over a wide field of view needed for semi-autonomous or autonomous operation of the UAV. This single-camera technique is potentially applicable for other robotic vehicles that may not be large enough for two-camera stereo. The range image is generated by tracking the motion of scene detail along optic flow lines. Performance is estimated in terms of the minimum and maximum ranges of scene detail that can be sensed as a function of its position within the field of view.

  15. Collision-induced dissociation of aflatoxins.

    PubMed

    Tóth, Katalin; Nagy, Lajos; Mándi, Attila; Kuki, Ákos; Mézes, Miklós; Zsuga, Miklós; Kéki, Sándor

    2013-02-28

    The aflatoxin mycotoxins are particularly hazardous to health when present in food. Therefore, from an analytical point of view, knowledge of their mass spectrometric properties is essential. The aim of the present study was to describe the collision-induced dissociation behavior of the four most common aflatoxins: B1, B2, G1 and G2. Protonated aflatoxins were produced using atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) combined with high-performance liquid chromatography (HPLC). For the tandem mass spectrometry (MS/MS) experiments nitrogen was used as the collision gas and the collision energies were varied in the range of 9-44 eV (in the laboratory frame). The major APCI-MS/MS fragmentations of protonated aflatoxins occurred at 30 eV collision energy. The main fragmentation channels were found to be the losses of a series of carbon monoxide molecules and loss of a methyl radical, leading to the formation of radical-type product ions. In addition, if the aflatoxin molecule contained an ether- or lactone-oxygen atom linked to a saturated carbon atom, loss of a water molecule was observed from the [M + H](+) ion, especially in the case of aflatoxins G1 and G2. A relatively small modification in the structure of aflatoxins dramatically altered the fragmentation pathways and this was particularly true for aflatoxins B1 and B2. Due to the presence of a C = C double bond connected to the ether group in aflatoxin B1 no elimination of water was observed but, instead, formation of radical-type product ions occurred. Fragmentation of protonated aflatoxin B1 yielded the most abundant radical-type cations. Copyright © 2013 John Wiley & Sons, Ltd.

  16. Operational Collision Avoidance

    NASA Technical Reports Server (NTRS)

    Guit, Bill

    2015-01-01

    This presentation will describe the early days of the EOS Aqua and Aura operational collision avoidance process. It will highlight EOS debris avoidance maneuvers, EOS high interest event statistic and A-Train systematic conjunctions and conclude with future challenges. This is related to earlier e-DAA (tracking number 21692) that an abstract was submitted to a different conference. Eric Moyer, ESMO Deputy Project Manager has reviewed and approved this presentation on May 6, 2015

  17. Collision Dynamics of Decimeter Bodies

    NASA Astrophysics Data System (ADS)

    Deckers, Johannes; Teiser, J.

    2013-10-01

    The collision dynamics of decimeter bodies are important for the early phase of planet formation. Planets form by accretion of km-sized objects, the so called planetesimals. These planetesimals evolve from small grains, but their formation process is not yet understood entirely. Two groups of models try to explain the formation process. Decimeter bodies and their collision behavior play a vital role in both groups. The threshold between bouncing and fragmentation is especially interesting for coagulation models, as decimeter bodies are the direct precursors to meter sized bodies. But the collision dynamics are also relevant for the models, which describe planetesimal formation by gravitational collapse in dense regions of the protoplanetary disk. We will present preliminary results of our collision experiments. Previous experiments on mutual collisions of decimeter dust agglomerates showed that the threshold between bouncing and fragmentation lies at a collision velocity of 16.2 cm/s, which corresponds to a specific kinetic energy of 5 mJ/kg. We expand these experiments to investigate the conditions for “catastrophic disruption” of decimeter dust bodies. Here, “catastrophic disruption” means that the largest fragment of a collision partner has only half the mass of the original body. Furthermore, we extend the parameter range to ice aggregates. We will present first experimental results of collisions of ice aggregates in the decimeter range. In these first experiments we will analyze the threshold conditions for solid ice. We will investigate the collision dynamics for both central and non-central collisions.

  18. Catching Collisions in the LHC

    SciTech Connect

    Fruguiele, Claudia; Hirschauer, Jim

    2015-06-16

    Now that the Large Hadron Collider has officially turned back on for its second run, within every proton collision could emerge the next new discovery in particle physics. Learn how the detectors on the Compact Muon Solenoid, or CMS, experiment capture and track particles as they are expelled from a collision. Talking us through these collisions are Claudia Fruguiele and Jim Hirschauer of Fermi National Accelerator Laboratory, the largest U.S. institution collaborating on the LHC.

  19. Catching Collisions in the LHC

    ScienceCinema

    Fruguiele, Claudia; Hirschauer, Jim

    2016-07-12

    Now that the Large Hadron Collider has officially turned back on for its second run, within every proton collision could emerge the next new discovery in particle physics. Learn how the detectors on the Compact Muon Solenoid, or CMS, experiment capture and track particles as they are expelled from a collision. Talking us through these collisions are Claudia Fruguiele and Jim Hirschauer of Fermi National Accelerator Laboratory, the largest U.S. institution collaborating on the LHC.

  20. Bubble collisions in general relativity

    NASA Astrophysics Data System (ADS)

    Sikos, S. T. C.; Wu, Z. C.

    The collision of two bubbles of true vacuum in a background of false vacuum is considered in the context of General Relativity. It is found that in the thin wall approximation, the problem can be solved exactly. The region to the future of the collision is described by the pseudo-Schwarzschild de Sitter metric. The parameters in this metric are found by solving the junction conditions at each collision.

  1. The collision hazard in space

    NASA Astrophysics Data System (ADS)

    Chobotov, V. A.

    1981-08-01

    The continuous use of space since 1957 has resulted in the buildup of a large number of space objects which represent an ever increasing collision hazard for current and future satellite systems. This study reviews the origin and distribution of the tracked and cataloged population of objects and examines the associated collision hazard at low altitudes and in the geosynchronous corridor. The effects of position uncertainty on the probability of collision between two objects at close encounter are evaluated. Representative design and operational policies which can reduce the collision hazard are discussed.

  2. Road rage and collision involvement.

    PubMed

    Mann, Robert E; Zhao, Jinhui; Stoduto, Gina; Adlaf, Edward M; Smart, Reginald G; Donovan, John E

    2007-01-01

    To assess the contribution of road rage victimization and perpetration to collision involvement. The relationship between self-reported collision involvement and road rage victimization and perpetration was examined, based on telephone interviews with a representative sample of 4897 Ontario adult drivers interviewed between 2002 and 2004. Perpetrators and victims of both any road rage and serious road rage had a significantly higher risk of collision involvement than did those without road rage experience. This study provides epidemiological evidence that both victims and perpetrators of road rage experience increased collision risk. More detailed studies of the contribution of road rage to traffic crashes are needed.

  3. D0 Detector Collision Hall Oxygen Deficiancy Hazard Analysis

    SciTech Connect

    Wu, J.; /Fermilab

    1992-08-06

    EN-258, D0 Platform ODH Analysts. provided the oxygen deficiency hazard analysts for the D0 detector in the Assembly Hall. This note covers the same analysis. but revised for the Collision Hall. Liquid cryogens. released and warming to atmosphere conditions, expand to, on average, seven hundred times their liquid volume, and displace vital atmospheric oxygen. An oxygen deficiency hazard analysis assesses the increased risk to personnel in areas containing cryogenic systems. The D0 detector Collision Hall ODH analysis has been approached five different ways using established methods. If the low beta quad magnets are powered, and the exhaust rate is below 4220 scfm, the area is ODH class 1. In any other case, the analysis shows the area to be ODH class 0 as equipped (with ventilation fans) and requiring no special safety provisions. System designers have provided for a reduced oxygen level detection and warning system as well as emergency procedures to address fault conditions.

  4. Mixing Diagnostics in Confined, High-Speed Droplet Collisions

    NASA Astrophysics Data System (ADS)

    Carroll, Brian; Hidrovo, Carlos

    2012-11-01

    Fast mixing remains a major challenge in droplet-based microfluidics. The low Reynolds number operating regime of most mixing devices signifies orderly flows that are devoid of any inertial characteristics. To increase droplet mixing rates, a novel technique is under development that uses a high Reynolds number gaseous phase for droplet generation and transport and promotes mixing through binary droplet collisions at velocities near 1m/s. Limitations in existing mixing diagnostic methodologies has persuaded cultivation of a new technique for measuring droplet collision mixing in confined microchannels. The technique employs single fluorophore laser-induced fluorescence, custom image processing, and meaningful statistical analysis for monitoring and quantifying mixing in high-speed droplet collisions. Mixing progress is revealed through two statistics that separate the roles of convective rearrangement and molecular diffusion during the mixing process. The end result is a viewing window into the rich dynamics of droplet collisions with spatial and temporal resolutions of 1 μm and 25 μs, respectively. Experimental results obtained across a decade of Reynolds and Peclet numbers reveal a direct link between droplet mixing time and the collision convective timescale. This work provides valuable insight into the emerging field of two-phase gas-liquid microfluidics and opens the door to fundamental research possibilities not offered by traditional oil-based architectures.

  5. Geochemical Interpretation of Collision Volcanism

    NASA Astrophysics Data System (ADS)

    Pearce, Julian

    2014-05-01

    Collision volcanism can be defined as volcanism that takes place during an orogeny from the moment that continental subduction starts to the end of orogenic collapse. Its importance in the Geological Record is greatly underestimated as collision volcanics are easily misinterpreted as being of volcanic arc, extensional or mantle plume origin. There are many types of collision volcanic province: continent-island arc collision (e.g. Banda arc); continent-active margin collision (e.g. Tibet, Turkey-Iran); continent-rear-arc collision (e.g. Bolivia); continent-continent collision (e.g. Tuscany); and island arc-island arc collision (e.g. Taiwan). Superimposed on this variability is the fact that every orogeny is different in detail. Nonetheless, there is a general theme of cyclicity on different time scales. This starts with syn-collision volcanism resulting from the subduction of an ocean-continent transition and continental lithosphere, and continues through post-collision volcanism. The latter can be subdivided into orogenic volcanism, which is related to thickened crust, and post-orogenic, which is related to orogenic collapse. Typically, but not always, collision volcanism is preceded by normal arc volcanism and followed by normal intraplate volcanism. Identification and interpretation of collision volcanism in the Geologic Record is greatly facilitated if a dated stratigraphic sequence is present so that the petrogenic evolution can be traced. In any case, the basis of fingerprinting collision terranes is to use geochemical proxies for mantle and subduction fluxes, slab temperatures, and depths and degrees of melting. For example, syn-collision volcanism is characterized by a high subduction flux relative to mantle flux because of the high input flux of fusible sediment and crust coupled with limited mantle flow, and because of high slab temperatures resulting from the decrease in subduction rate. The resulting geochemical patterns are similar regardless of

  6. Charge transfer during individual collisions in ice growing by riming

    NASA Technical Reports Server (NTRS)

    Avila, Eldo E.; Caranti, Giorgio M.

    1991-01-01

    The charging of a target by riming in the wind was studied in the temperature range of (-10, -18 C). For each temperature, charge transfers of both signs are observed and, according to the environmental conditions, one of them prevails. The charge is more positive as the liquid water concentration is increased at any particular temperature. It is found that even at the low impact velocities used (5 m/s) there is abundant evidence of fragmentation following the collision.

  7. Electron Collisions with Hydrogen Fluoride

    NASA Astrophysics Data System (ADS)

    Itikawa, Yukikazu

    2017-03-01

    Cross section data are reviewed for electron collisions with hydrogen fluoride. Collision processes considered are total scattering, elastic scattering, excitations of rotational, vibrational, and electronic states, ionization, and dissociative electron attachment. After a survey of the literature, recommended values of the cross sections are determined, as far as possible.

  8. Spin Changing Collisions of Hydrogen

    NASA Technical Reports Server (NTRS)

    Zygelman, Bernard

    2006-01-01

    We discuss spin changing collisions of hydrogen atoms. Employing a fully quantal theory we calculate and present new collision data. We discuss the respective roles of spin exchange and long range magnetic interactions in collisonal redistribution of sub-level populations. The calculated atomic data is needed for accurate modeling of 21 cm line emission/absorption by primordial hydrogen in the early universe.

  9. Ultracold collisions in metastable helium

    NASA Astrophysics Data System (ADS)

    Peach, G.; Cocks, D. G.; Whittingham, I. B.

    2017-02-01

    Photoassociation processes are studied in ultracold collisions between different isotopes of metastable He(23S) and He(23P) atoms; Penning and associative ionization rates for collisions between two He(23S) atoms are also obtained. Comparisons are made with data from existing experiments.

  10. Collision in space

    NASA Technical Reports Server (NTRS)

    Ellis, S. R.

    2000-01-01

    On June 25, 1997, the Russian supply spacecraft Progress 234 collided with the Mir space station, rupturing Mir's pressure hull, throwing it into an uncontrolled attitude drift, and nearly forcing evacuation of the station. Like many high-profile accidents, this collision was the consequence of a chain of events leading to the final piloting errors that were its immediate cause. The discussion in this article does not resolve the relative contributions of the actions and decisions in this chain. Neither does it suggest corrective measures, many of which are straightforward and have already been implemented by the National Aeronautics and Space Administration (NASA) and the Russian Space Agency. Rather, its purpose is to identify the human factors that played a pervasive role in the incident. Workplace stress, fatigue, and sleep deprivation were identified by NASA as contributory factors in the Mir-Progress collision (Culbertson, 1997; NASA, forthcoming), but other contributing factors, such as requiring crew to perform difficult tasks for which their training is not current, could potentially become important factors in future situations.

  11. Collision in space.

    PubMed

    Ellis, S R

    2000-01-01

    On June 25, 1997, the Russian supply spacecraft Progress 234 collided with the Mir space station, rupturing Mir's pressure hull, throwing it into an uncontrolled attitude drift, and nearly forcing evacuation of the station. Like many high-profile accidents, this collision was the consequence of a chain of events leading to the final piloting errors that were its immediate cause. The discussion in this article does not resolve the relative contributions of the actions and decisions in this chain. Neither does it suggest corrective measures, many of which are straightforward and have already been implemented by the National Aeronautics and Space Administration (NASA) and the Russian Space Agency. Rather, its purpose is to identify the human factors that played a pervasive role in the incident. Workplace stress, fatigue, and sleep deprivation were identified by NASA as contributory factors in the Mir-Progress collision (Culbertson, 1997; NASA, forthcoming), but other contributing factors, such as requiring crew to perform difficult tasks for which their training is not current, could potentially become important factors in future situations.

  12. Collision in space

    NASA Technical Reports Server (NTRS)

    Ellis, S. R.

    2000-01-01

    On June 25, 1997, the Russian supply spacecraft Progress 234 collided with the Mir space station, rupturing Mir's pressure hull, throwing it into an uncontrolled attitude drift, and nearly forcing evacuation of the station. Like many high-profile accidents, this collision was the consequence of a chain of events leading to the final piloting errors that were its immediate cause. The discussion in this article does not resolve the relative contributions of the actions and decisions in this chain. Neither does it suggest corrective measures, many of which are straightforward and have already been implemented by the National Aeronautics and Space Administration (NASA) and the Russian Space Agency. Rather, its purpose is to identify the human factors that played a pervasive role in the incident. Workplace stress, fatigue, and sleep deprivation were identified by NASA as contributory factors in the Mir-Progress collision (Culbertson, 1997; NASA, forthcoming), but other contributing factors, such as requiring crew to perform difficult tasks for which their training is not current, could potentially become important factors in future situations.

  13. Water ball collision

    NASA Technical Reports Server (NTRS)

    Fujimoto, K.

    1986-01-01

    What happens if a stainless steel ball hits a water ball in the weightless space ot the Universe? In other words, it was the objective of our experiments in the Space to observe the surface tension of liquid by means of making a solid collide with a liquid. Place a small volume of water between 2 glass sheets to make a thin water membrane: the 2 glass sheets cannot be separated unless an enormous force is applied. It is obvious from this phenomenom that the surface tension of water is far greater than presumed. On Earth, however, it is impossible in most cases to observe only the surface tension of liquid, because gravity always acts on the surface tension. Water and stainless steel balls were chosen the liquid and solids for the experiments. Because water is the liquid most familiar to us, its properties are well known. And it is also of great interest to compare its properties on the Earth with those in the weightless space.

  14. Recognition of movement object collision

    NASA Astrophysics Data System (ADS)

    Chang, Hsiao Tsu; Sun, Geng-tian; Zhang, Yan

    1991-03-01

    The paper explores the collision recognition of two objects in both crisscross and revolution motions A mathematical model has been established based on the continuation theory. The objects of any shape may be regarded as being built of many 3siniplexes or their convex hulls. Therefore the collision problem of two object in motion can be reduced to the collision of two corresponding 3siinplexes on two respective objects accordingly. Thus an optimized algorithm is developed for collision avoidance which is suitable for computer control and eliminating the need for vision aid. With this algorithm computation time has been reduced significantly. This algorithm is applicable to the path planning of mobile robots And also is applicable to collision avoidance of the anthropomorphic arms grasping two complicated shaped objects. The algorithm is realized using LISP language on a VAX8350 minicomputer.

  15. Reversible simulations of elastic collisions

    SciTech Connect

    Perumalla, Kalyan S.; Protopopescu, Vladimir A.

    2013-05-01

    Consider a system of N identical hard spherical particles moving in a d-dimensional box and undergoing elastic, possibly multi-particle, collisions. We develop a new algorithm that recovers the pre-collision state from the post-collision state of the system, across a series of consecutive collisions, \\textit{with essentially no memory overhead}. The challenge in achieving reversibility for an n-particle collision (where, in general, n<< N) arises from the presence of nd-d-1 degrees of freedom (arbitrary angles) during each collision, as well as from the complex geometrical constraints placed on the colliding particles. To reverse the collisions in a traditional simulation setting, all of the particular realizations of these degrees of freedom (angles) during the forward simulation must be tracked. This requires memory proportional to the number of collisions, which grows very fast with N and d, thereby severely limiting the \\textit{de facto} applicability of the scheme. This limitation is addressed here by first performing a pseudo-randomization of angles, which ensures determinism in the reverse path for any values of n and d. To address the more difficult problem of geometrical and dynamic constraints, a new approach is developed which correctly samples the constrained phase space. Upon combining the pseudo-randomization with correct phase space sampling, perfect reversibility of collisions is achieved, as illustrated for n<=3, d=2, and n=2, d=3. This result enables, for the first time, reversible simulations of elastic collisions with essentially zero memory accumulation. In principle, the approach presented here could be generalized to larger values of n, which would be of definite interest for molecular dynamics simulations at high densities.

  16. Sixteenth International Conference on the physics of electronic and atomic collisions

    SciTech Connect

    Dalgarno, A.; Freund, R.S.; Lubell, M.S.; Lucatorto, T.B.

    1989-01-01

    This report contains abstracts of papers on the following topics: photons, electron-atom collisions; electron-molecule collisions; electron-ion collisions; collisions involving exotic species; ion- atom collisions, ion-molecule or atom-molecule collisions; atom-atom collisions; ion-ion collisions; collisions involving rydberg atoms; field assisted collisions; collisions involving clusters and collisions involving condensed matter.

  17. Geosynchronous satellite collision avoidance

    NASA Technical Reports Server (NTRS)

    Fraser, W.

    1985-01-01

    The increases in the number of satellite systems, the growing dependency on these systems, and the potentially hazardous conjunctions in space, dictates careful management of satellite positions. The potential for satellite collision increases as more objects are placed in orbit. At geosynchronous altitudes active satellites maintain fixed longitudinal station-keeping control while inactive satellites and debris generally drift around the globe or oscillate about two geopotential stable points. Portions of the total objects in geosynchronous orbit are tracked by ground stations while a significant number of additional pieces of space debris regularly pass through geosynchronous orbit altitudes. The probability of an operational satellite colliding with another satellite or a piece of space debris will increase in the number of space objects, their sizes, and on-orbit lifetimes.

  18. Collision avoidance sensor skin

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The objective was to totally eliminate the possibility of a robot (or any mechanism for that matter) inducing a collision in space operations. We were particularly concerned that human beings were safe under all circumstances. This was apparently accomplished, and it is shown that GSFC has a system that is ready for space qualification and flight. However, it soon became apparent that much more could be accomplished with this technology. Payloads could be made invulnerable to collision avoidance and the blind spots behind them eliminated. This could be accomplished by a simple, non-imaging set of 'Capaciflector' sensors on each payload. It also is evident that this system could be used to align and dock the system with a wide margin of safety. Throughout, lighting problems could be ignored, and unexpected events and modeling errors taken in stride. At the same time, computational requirements would be reduced. This can be done in a simple, rugged, reliable manner that will not disturb the form factor of space systems. It will be practical for space applications. The lab experiments indicate we are well on the way to accomplishing this. Still, the research trail goes deeper. It now appears that the sensors can be extended to end effectors to provide precontact information and make robot docking (or any docking connection) very smooth, with minimal loads impacted back into the mating structures. This type of ability would be a major step forward in basic control techniques in space. There are, however, baseline and restructuring issues to be tackled. The payloads must get power and signals to them from the robot or from the astronaut servicing tool. This requires a standard electromechanical interface. Any of several could be used. The GSFC prototype shown in this presentation is a good one. Sensors with their attendant electronics must be added to the payloads, end effectors, and robot arms and integrated into the system.

  19. Collisions in the Oort Cloud

    SciTech Connect

    Stern, S.A.

    1988-03-01

    The present assessment of the consequentiality of physical collisions between Oort Cloud objects by a first-generation model indicates that natural power-law population structures produce significant numbers of collisions between each comet and smaller objects over the age of the solar system. These collisions are held to constitute a feedback mechanism for small debris production. The impacts yield extensive comet surface evolution in the cloud, in conditions where the number of small orbiting objects conforms to the standard power-law populations. 16 references.

  20. Theoretical studies of molecular collisions

    NASA Technical Reports Server (NTRS)

    Kouri, Donald J.

    1991-01-01

    The following subject areas are covered: (1) total integral reactive cross sections and vibrationally resolved reaction probabilities for F + H2 = HF + H; (2) a theoretical study of inelastic O + N2 collisions; (3) body frame close coupling wave packet approach to gas phase atom-rigit rotor inelastic collisions; (4) wave packet study of gas phase atom-rigit motor scattering; (5) the application of optical potentials for reactive scattering; (6) time dependent, three dimensional body frame quantal wave packet treatment of the H + H2 exchange reaction; (7) a time dependent wave packet approach to atom-diatom reactive collision probabilities; (8) time dependent wave packet for the complete determination of s-matrix elements for reactive molecular collisions in three dimensions; (9) a comparison of three time dependent wave packet methods for calculating electron-atom elastic scattering cross sections; and (10) a numerically exact full wave packet approach to molecule-surface scattering.

  1. Continental collisions and seismic signature

    NASA Astrophysics Data System (ADS)

    Meissner, R.; Wever, Th.; Sadowiak, P.

    1991-04-01

    Reflection seismics in compressional belts has revealed the structure of crustal shortening and thickening processes, showing complex patterns of indentation and interfingering of colliding crusts and subcrustal lithospheres. Generally, in the upper crust large zones of detachments develop, often showing duplexes and 'crocodile' structures. The lower crust from zones of active collision (e.g. Alps, Pyrenees) is characterized by strongly dipping reflections. The base of the crust with the Moho must be continuously equilibrating after orogenic collapse as areas of former continental collision exhibit flat Mohos and subhorizontal reflections. The depth to the Moho increases during collision and decreases after the onset of post-orogenic extension, until finally the crustal root disappears completely together with the erosion of the mountains. Processes, active during continental collisions and orogenic collapse, create distinct structures which are imaged by reflection seismic profiling. Examples are shown and discussed.

  2. Collisions of Vortex Filament Pairs

    NASA Astrophysics Data System (ADS)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  3. Robot Avoids Collisions With Obstacles

    NASA Technical Reports Server (NTRS)

    Cheung, Edward; Rosinski, Doug; Wegerif, Dan

    1993-01-01

    Developmental robot equipped with infrared sensors and control system acting in concert to enable manipulator arm to move around obstacles. Robot avoids collisions with other objects, even when moving in unpredictable ways. Control system requires no prior knowledge of environment.

  4. Milky Way's Head On Collision

    NASA Image and Video Library

    This animation depicts the collision between our Milky Way galaxy and the Andromeda galaxy. Hubble Space Telescope observations indicate that the two galaxies, pulled together by their mutual gravi...

  5. Investigation of wetted particle collisions theoretically and experimentally using a pendulum apparatus

    NASA Astrophysics Data System (ADS)

    Donahue, Carly Michelle

    The addition of a small amount of liquid to a granular system can dramatically change the flow dynamics including the flowability, tensile strength, and segregation. Such liquid-coated particles coated are common in nature (e.g. avalanches, pollen capture) and in industry (e.g. granulation, particle filtration). Despite their ubiquity, predicting macro-scale (bulk) flows of liquid-coated particles is still elusive. A microscale (particle-level) investigation of the interactions of few wetted particles will lead to the identification of the dominant physical mechanisms which feeds into the understanding and modeling of bulk flows of wetted systems. Previous micro-scale studies of wetted particles have included experimental and theoretical efforts to study particle-wall collisions (both oblique and head-on) and particle-particle collisions (head-on only). Before using such micro-scale models to describe macro-scale flows, more general cases need to be first considered such as collisions between more than two particles and the rotational motion of agglomerates. The goal of this work is to address these two issues through a combination of experiments using a pendulum apparatus and theory. To investigate collisions between more than two particles, this work focuses on the normal (head-on) collision of three spheres. The foundation for such work is provided by first investigating analogous dry (non-wetted) systems. Experimental results are compared to soft-sphere models, which simultaneously account for all collisions, and a hard-sphere model, which treats the three-body collision as a series of two-body collisions. While the soft-sphere models generally predicts the post-collisional velocities better, the hard-sphere model exhibits a good comparison overall. In the wetted three-particle collisions, the pendulum apparatus is coined Stokes's cradle for the Stokes flow in the liquid gap between the particles. In two-body collisions, only two outcomes exist, namely stick

  6. Modelling droplet collision outcomes for different substances and viscosities

    NASA Astrophysics Data System (ADS)

    Sommerfeld, Martin; Kuschel, Matthias

    2016-12-01

    The main objective of the present study is the derivation of models describing the outcome of binary droplet collisions for a wide range of dynamic viscosities in the well-known collision maps (i.e. normalised lateral droplet displacement at collision, called impact parameter, versus collision Weber number). Previous studies by Kuschel and Sommerfeld (Exp Fluids 54:1440, 2013) for different solution droplets having a range of solids contents and hence dynamic viscosities (here between 1 and 60 mPa s) revealed that the locations of the triple point (i.e. coincidence of bouncing, stretching separation and coalescence) and the critical Weber number (i.e. condition for the transition from coalescence to separation for head-on collisions) show a clear dependence on dynamic viscosity. In order to extend these findings also to pure liquids and to provide a broader data basis for modelling the viscosity effect, additional binary collision experiments were conducted for different alcohols (viscosity range 1.2-15.9 mPa s) and the FVA1 reference oil at different temperatures (viscosity range 3.0-28.2 mPa s). The droplet size for the series of alcohols was around 365 and 385 µm for the FVA1 reference oil, in each case with fixed diameter ratio at Δ= 1. The relative velocity between the droplets was varied in the range 0.5-3.5 m/s, yielding maximum Weber numbers of around 180. Individual binary droplet collisions with defined conditions were generated by two droplet chains each produced by vibrating orifice droplet generators. For recording droplet motion and the binary collision process with good spatial and temporal resolution high-speed shadow imaging was employed. The results for varied relative velocity and impact angle were assembled in impact parameter-Weber number maps. With increasing dynamic viscosity a characteristic displacement of the regimes for the different collision scenarios was also observed for pure liquids similar to that observed for solutions. This

  7. Do speed cameras reduce collisions?

    PubMed

    Skubic, Jeffrey; Johnson, Steven B; Salvino, Chris; Vanhoy, Steven; Hu, Chengcheng

    2013-01-01

    We investigated the effects of speed cameras along a 26 mile segment in metropolitan Phoenix, Arizona. Motor vehicle collisions were retrospectively identified according to three time periods - before cameras were placed, while cameras were in place and after cameras were removed. A 14 mile segment in the same area without cameras was used for control purposes. Five cofounding variables were eliminated. In this study, the placement or removal of interstate highway speed cameras did not independently affect the incidence of motor vehicle collisions.

  8. Surface Collisions Involving Particles and Moisture (SCIP'M)

    NASA Technical Reports Server (NTRS)

    Davis, Robert H.

    2005-01-01

    Experiments were performed on the collision of a solid sphere with a nearly horizontal flat surface covered with a thin layer of viscous liquid. High-speed collisions were obtained by dropping the ball onto the surface from various heights, using gravitational acceleration. Low-speed collisions were obtained using pendulums with long strings or by launching the balls at low velocities in the reduced-gravity environment of parabolic flight. The sphere bounces only when the impact velocity exceeds a critical value. The coefficient of restitution (ratio of rebound velocity to impact velocity) increases with increasing impact velocity above the critical value, indicating the increasing relative importance of elastic deformation to viscous dissipation. The critical impact velocity increases, and the coefficient of restitution decreases, with increasing viscosity or thickness of the liquid layer and with decreasing density or size of the sphere. The ratio of the wet and dry coefficients is expressed as a function of the Stokes number (ratio of particle inertia and viscous forces), showing good agreement between theory and experiment. Similar experiments were performed with the flat surface inclined at various angles to the approaching sphere. A modified Stokes number, which is a measure of the ratio of inertia of the sphere in the normal direction to the viscous forces exerted by the fluid layer, was used for the analysis of oblique collisions. Even for these oblique collisions, it was found that no rebound of the ball was observed below a certain critical Stokes number. The coefficient of normal restitution, defined as a ratio of normal rebound velocity to normal approach velocity, was found to increase beyond the critical Stokes number and even out as it approaches the value for dry restitution at high Stokes numbers. It was also found that, for smooth spheres like steel, the normal restitution at the same modified Stokes number is independent of the angle of impact

  9. Dynamics of droplet collision and flame-front motion

    NASA Astrophysics Data System (ADS)

    Pan, Kuo-Long

    Three physical phenomena were experimentally and computationally investigated in this research, namely the dynamics of head-on droplet-droplet collision, head-on droplet-film collision, and laminar premixed flames, with emphasis on the transition between bouncing and merging of the liquid surfaces for the droplet collision studies, and on the susceptibility to exhibit hydrodynamic instability for the flame dynamics. All three problems share the common feature of having an active deformable interface separating two flow regions of disparate densities, and as such can be computationally described using the adopted immersed boundary technique. Experimentally, the droplets (˜300 mum diameter) were generated using the ink jet printing technique, and imaged using stroboscopy for the droplet-droplet collision events and high-speed cine-photography for the droplet-film collision events. For the study of droplet-droplet collision, the instant of merging was experimentally determined and then used as an input in the computational simulation of the entire collision event. The simulation identified the differences between collision and merging at small and large Weber numbers, and satisfactorily described the dynamics of the inter-droplet gap including the role of the van der Waals force in effecting surface rupture. For the study of droplet-film collision, extensive experimental mapping showed that the collision dynamics is primarily affected by the droplet Weber number (We) and the film thickness scaled by the droplet radius (H), that while droplet absorption by the film is facilitated with increasing droplet Weber number, the boundary of transition is punctuated by an absorption peninsula, in the We-H space, within which absorption is further facilitated for smaller Weber numbers. Results from computation simulation revealed the essential dependence of the collision dynamics on the restraining nature of the solid surface, the energy exchange between the droplet and the

  10. Analyzing Benzene and Cyclohexane Emulsion Droplet Collisions on Ultramicroelectrodes.

    PubMed

    Li, Yan; Deng, Haiqiang; Dick, Jeffrey E; Bard, Allen J

    2015-11-03

    We report the collisions of single emulsion oil droplets with extremely low dielectric constants (e.g., benzene, ε of 2.27, or cyclohexane, ε of 2.02) as studied via emulsion droplet reactor (EDR) on an ultramicroelectrode (UME). By applying appropriate potentials to the UME, we observed the electrochemical effects of single-collision signals from the bulk electrolysis of single emulsion droplets. Different hydrophobic redox species (ferrocene, decamethyl-ferrocene, or metalloporphyrin) were trapped in a mixed benzene (or cyclohexane) oil-in-water emulsion using an ionic liquid as the supporting electrolyte and emulsifier. The emulsions were prepared using ultrasonic processing. Spike-like responses were observed in each i-t response due to the complete electrolysis of all of the above-mentioned redox species within the droplet. On the basis of these single-particle collision results, the collision frequency, size distribution, i-t decay behavior of the emulsion droplets, and possible mechanisms are analyzed and discussed. This work demonstrated that bulk electrolysis can be achieved in a few seconds in these attoliter reactors, suggesting many applications, such as analysis and electrosynthesis in low dielectric constant solvents, which have a much broader potential window.

  11. Automatic Collision Avoidance Technology (ACAT)

    NASA Technical Reports Server (NTRS)

    Swihart, Donald E.; Skoog, Mark A.

    2007-01-01

    This document represents two views of the Automatic Collision Avoidance Technology (ACAT). One viewgraph presentation reviews the development and system design of Automatic Collision Avoidance Technology (ACAT). Two types of ACAT exist: Automatic Ground Collision Avoidance (AGCAS) and Automatic Air Collision Avoidance (AACAS). The AGCAS Uses Digital Terrain Elevation Data (DTED) for mapping functions, and uses Navigation data to place aircraft on map. It then scans DTED in front of and around aircraft and uses future aircraft trajectory (5g) to provide automatic flyup maneuver when required. The AACAS uses data link to determine position and closing rate. It contains several canned maneuvers to avoid collision. Automatic maneuvers can occur at last instant and both aircraft maneuver when using data link. The system can use sensor in place of data link. The second viewgraph presentation reviews the development of a flight test and an evaluation of the test. A review of the operation and comparison of the AGCAS and a pilot's performance are given. The same review is given for the AACAS is given.

  12. Continuum and molecular-dynamics simulation of nanodroplet collisions.

    PubMed

    Bardia, Raunak; Liang, Zhi; Keblinski, Pawel; Trujillo, Mario F

    2016-05-01

    The extent to which the continuum treatment holds in binary droplet collisions is examined in the present work by using a continuum-based implicit surface capturing strategy (volume-of-fluid coupled to Navier-Stokes) and a molecular dynamics methodology. The droplet pairs are arranged in a head-on-collision configuration with an initial separation distance of 5.3 nm and a velocity of 3 ms^{-1}. The size of droplets ranges from 10-50 nm. Inspecting the results, the collision process can be described as consisting of two periods: a preimpact phase that ends with the initial contact of both droplets, and a postimpact phase characterized by the merging, deformation, and coalescence of the droplets. The largest difference between the continuum and molecular dynamics (MD) predictions is observed in the preimpact period, where the continuum-based viscous and pressure drag forces significantly overestimate the MD predictions. Due to large value of Knudsen number in the gas (Kn_{gas}=1.972), this behavior is expected. Besides the differences between continuum and MD, it is also observed that the continuum simulations do not converge for the set of grid sizes considered. This is shown to be directly related to the initial velocity profile and the minute size of the nanodroplets. For instance, for micrometer-size droplets, this numerical sensitivity is not an issue. During the postimpact period, both MD and continuum-based simulations are strikingly similar, with only a moderate difference in the peak kinetic energy recorded during the collision process. With values for the Knudsen number in the liquid (Kn_{liquid}=0.01 for D=36nm) much closer to the continuum regime, this behavior is expected. The 50 nm droplet case is sufficiently large to be predicted reasonably well with the continuum treatment. However, for droplets smaller than approximately 36 nm, the departure from continuum behavior becomes noticeably pronounced, and becomes drastically different for the 10 nm

  13. POLARIZED PROTON COLLISIONS AT RHIC.

    SciTech Connect

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; ET AL.

    2005-05-16

    The Relativistic Heavy Ion Collider provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC. In 2002, polarized proton beams were first accelerated to 100 GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. Optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limited conditions are reported.

  14. Semiholography for heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Ayan; Preis, Florian

    2017-03-01

    The formation of QGP in heavy ion collisions gives us a great opportunity for learning about nonperturbative dynamics of QCD. Semiholography provides a new consistent framework to combine perturbative and non-perturbative effects in a coherent way and can be applied to obtain an effective description for heavy ion collisions. In particular, it allows us to include nonperturbative effects in existing glasma effective theory and QCD kinetic theory for the weakly coupled saturated degrees of freedom liberated by the collisions in the initial stages in a consistent manner. We argue why the full framework should be able to confront experiments with only a few phenomenological parameters and present feasibility tests for the necessary numerical computations. Furthermore, we discuss that semiholography leads to a new description of collective flow in the form of a generalised non-Newtonian fluid. We discuss some open questions which we hope to answer in the near future.

  15. A problem of collision avoidance

    NASA Technical Reports Server (NTRS)

    Vincent, T. L.; Cliff, E. M.; Grantham, W. J.; Peng, W. Y.

    1972-01-01

    Collision avoidance between two vehicles of constant speed with limited turning radii, moving in a horizontal plane is investigated. Collision avoidance is viewed as a game by assuming that the operator of one vehicle has perfect knowledge of the state of the other, whereas the operator of the second vehicle is unaware of any impending danger. The situation envisioned is that of an encounter between a commercial aircraft and a small light aircraft. This worse case situation is examined to determine the conditions under which the commercial aircraft should execute a collision avoidance maneuver. Three different zones of vulnerability are defined and the boundaries, or barriers, between these zones are determined for a typical aircraft encounter. A discussion of the methods used to obtain the results as well as some of the salient features associated with the resultant barriers is included.

  16. Outreach Materials for the Collision Repair Campaign

    EPA Pesticide Factsheets

    The Collision Repair Campaign offers outreach materials to help collision repair shops reduce toxic air exposure. Materials include a DVD, poster, training video, and materials in Spanish (materiales del outreach en español).

  17. ACAT Ground Collision Avoidance Flight Tests Over

    NASA Image and Video Library

    NASA's Dryden Flight Research Center has concluded flight tests of an Automatic Ground Collision Avoidance System (Auto GCAS) under the joint U.S. Air Force/NASA F-16D Automatic Collision Avoidance...

  18. Atomic Collisions and Plasma Physics.

    DTIC Science & Technology

    1984-01-31

    AD-R141 320 ATOMIC COLLISIONS AND PLASMA PHYSICS(U) PITTSBURGH UNIV i/il PR DEPT OF PHYSICS AND ASTRONOMY M R BIONDI 3i JAN 84 RFGL-TR-94-044 Fi9628...OF STANDARDS t963 A % : C~44 h ’ I ATOMIC COLLISIONS AND PLASMA PHYSICS Manfred A. Biondi Department of Physics and Astronomy University of Pittsburgh... PLASMA PHYSICS Final - 11/1/80 - 12/31/83 6 PI kF%oMINC. OR. REPORT NUMA4I R 7. AUTHO R(j iS CONTRACTOR GRANT NUM8ER(. * Manfred A. Biondi Fl9628-81

  19. Multidimensional intermittency in hadronic collisions

    NASA Astrophysics Data System (ADS)

    Pan, Jicai; Hwa, Rudolph C.

    1992-12-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ecco is extended to three-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in lnpT, and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle φ. The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent ν=1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined.

  20. Multidimensional intermittency in hadronic collisions

    NASA Astrophysics Data System (ADS)

    Pan, J.; Hwa, R. C.

    1992-06-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ECCO is extended to 3-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in 1np(sub T), and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle (phi). The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent nu = 1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined.

  1. Do Speed Cameras Reduce Collisions?

    PubMed Central

    Skubic, Jeffrey; Johnson, Steven B.; Salvino, Chris; Vanhoy, Steven; Hu, Chengcheng

    2013-01-01

    We investigated the effects of speed cameras along a 26 mile segment in metropolitan Phoenix, Arizona. Motor vehicle collisions were retrospectively identified according to three time periods – before cameras were placed, while cameras were in place and after cameras were removed. A 14 mile segment in the same area without cameras was used for control purposes. Five cofounding variables were eliminated. In this study, the placement or removal of interstate highway speed cameras did not independently affect the incidence of motor vehicle collisions. PMID:24406979

  2. Signature of anisotropic bubble collisions

    SciTech Connect

    Salem, Michael P.

    2010-09-15

    Our universe may have formed via bubble nucleation in an eternally inflating background. Furthermore, the background may have a compact dimension--the modulus of which tunnels out of a metastable minimum during bubble nucleation--which subsequently grows to become one of our three large spatial dimensions. When in this scenario our bubble universe collides with other ones like it, the collision geometry is constrained by the reduced symmetry of the tunneling instanton. While the regions affected by such bubble collisions still appear (to leading order) as disks in an observer's sky, the centers of these disks all lie on a single great circle, providing a distinct signature of anisotropic bubble nucleation.

  3. Dissipative heavy-ion collisions

    SciTech Connect

    Feldmeier, H.T.

    1985-01-01

    This report is a compilation of lecture notes of a series of lectures held at Argonne National Laboratory in October and November 1984. The lectures are a discussion of dissipative phenomena as observed in collisions of atomic nuclei. The model is based on a system which has initially zero temperature and the initial energy is kinetic and binding energy. Collisions excite the nuclei, and outgoing fragments or the compound system deexcite before they are detected. Brownian motion is used to introduce the concept of dissipation. The master equation and the Fokker-Planck equation are derived. 73 refs., 59 figs. (WRF)

  4. Dynamics of Droplet Collision and Flamefront Motion

    DTIC Science & Technology

    2005-12-01

    effecting droplet bouncing versus absorption. (4) The dynamics of flame motion when it is subjected to the combined hydrodynamic and body-force instabilities...and freestream vortical motion. 15. SUBJECT TERMS Droplet collision; droplet-film collision; van der Waals force; droplet bouncing ; droplet...collision of two droplets. For example, they can either merge to form a larger droplet, or bounce away from each other. Furthermore, the collision event has

  5. 49 CFR 238.211 - Collision posts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... structural protection described in paragraph (a) of this section, either: (1) Two forward collision posts... structural protection described in paragraphs (a) and (b) of this section, two forward collision posts... body structure. (3) Prior to or during structural deformation, each collision post acting together with...

  6. 49 CFR 238.211 - Collision posts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... structural protection described in paragraph (a) of this section, either: (1) Two forward collision posts... structural protection described in paragraphs (a) and (b) of this section, two forward collision posts... body structure. (3) Prior to or during structural deformation, each collision post acting together with...

  7. 49 CFR 238.211 - Collision posts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... structural protection described in paragraph (a) of this section, either: (1) Two forward collision posts... structural protection described in paragraphs (a) and (b) of this section, two forward collision posts... body structure. (3) Prior to or during structural deformation, each collision post acting together with...

  8. LIQUID-LIQUID EXTRACTION COLUMNS

    DOEpatents

    Thornton, J.D.

    1957-12-31

    This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.

  9. Probing GPDs in ultraperipheral collisions

    SciTech Connect

    Ivanov, D.Yu.; Pire, B.; Szymanowski, L.; Wagner, J.

    2015-04-10

    Ultraperipheral collisions in hadron colliders give new opportunities to investigate the hadron structure through exclusive photoproduction processes. We describe the possibility of measuring the Generalized Parton Distributions in the Timelike Compton Scattering process and in the production of heavy vector meson.

  10. Quarkonium production in hadronic collisions

    SciTech Connect

    Gavai, R.; Schuler, G.A.; Sridhar, K.

    1995-07-01

    We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.

  11. Duration of an Elastic Collision

    ERIC Educational Resources Information Center

    de Izarra, Charles

    2012-01-01

    With a pedagogical goal, this paper deals with a study of the duration of an elastic collision of an inflatable spherical ball on a planar surface suitable for undergraduate studies. First, the force generated by the deformed spherical ball is obtained under assumptions that are discussed. The study of the motion of the spherical ball colliding…

  12. Collision Between Two Spiral Galaxies

    NASA Image and Video Library

    2008-04-24

    NGC 6050/IC 1179 Arp 272 is a remarkable collision between two spiral galaxies, NGC 6050 and IC 1179, and is part of the Hercules Galaxy Cluster, located in the constellation of Hercules. This image is from NASA Hubble Space Telescope.

  13. Duration of an Elastic Collision

    ERIC Educational Resources Information Center

    de Izarra, Charles

    2012-01-01

    With a pedagogical goal, this paper deals with a study of the duration of an elastic collision of an inflatable spherical ball on a planar surface suitable for undergraduate studies. First, the force generated by the deformed spherical ball is obtained under assumptions that are discussed. The study of the motion of the spherical ball colliding…

  14. High velocity collisions of nanoparticles

    NASA Astrophysics Data System (ADS)

    Johnson, Donald F.; Mattson, William D.

    2017-01-01

    Nanoparticles (NPs) are a unique class of material with highly functionalizable surfaces and exciting applications. With a large surface-to-volume ratio and potentially high surface tension, shocked nanoparticles might display unique materials behavior. Using density functional theory, we have simulated high-velocity NP collisions under a variety of conditions. NPs composed of diamond-C, cubic-BN, and diamond-Si were considered with particle sizes up to 3.5 nm diameter. Additional simulations involved NPs that were destabilized by incorporating internal strain. The initial spherical NP structures were carved out of bulk crystals while the NPs with internal strain were constructed as a dense core (compressive strain) encompassed by a thin shell (tensile strain). Both on-axis and off-axis collisions were simulated at 10 km/s relative velocity. The amount of internal strain was artificially increased by creating a dense inner core with bond lengths compressed up to 8%. Collision dynamics, shock propagation, and fragmentation will be analyzed, but the simulation are ongoing and results are not finalized. The effect of material properties, internal strain, and collision velocity will be discussed.

  15. Sequential binary collision ionization mechanisms

    NASA Astrophysics Data System (ADS)

    van Boeyen, R. W.; Watanabe, N.; Doering, J. P.; Moore, J. H.; Coplan, M. A.; Cooper, J. W.

    2004-03-01

    Fully differential cross sections for the electron-impact ionization of the magnesium 3s orbital have been measured in a high-momentum-transfer regime wherein the ionization mechanisms can be accurately described by simple binary collision models. Measurements where performed at incident-electron energies from 400 to 3000 eV, ejected-electron energies of 62 eV, scattering angle of 20 °, and momentum transfers of 2 to 5 a.u. In the out-of-plane geometry of the experiment the cross section is observed far off the Bethe ridge. Both first- and second-order processes can be clearly distinguished as previously observed by Murray et al [Ref. 1] and Schulz et al [Ref. 2]. Owing to the relatively large momentum of the ejected electron, the second order processes can be modeled as sequential binary collisions involving a binary elastic collision between the incident electron and ionic core and a binary knock-out collision between the incident electron and target electron. At low incident-electron energies the cross section for both first and second order processes are comparable, while at high incident energies second-order processes dominate. *Supported by NSF under grant PHY-99-87870. [1] A. J. Murray, M. B. J. Woolf, and F. H. Read J. Phys. B 25, 3021 (1992). [2] M. Schulz, R. Moshammer, D. Fischer, H. Kollmus, D. H. Madison. S. Jones and J. Ullrich, Nature 422, 48 (2003).

  16. Photonic, Electronic and Atomic Collisions

    NASA Astrophysics Data System (ADS)

    Fainstein, Pablo D.; Lima, Marco Aurelio P.; Miraglia, Jorge E.; Montenegro, Eduardo C.; Rivarola, Roberto D.

    2006-11-01

    Plenary. Electron collisions - past, present and future / J. W. McConkey. Collisions of slow highly charged ions with surfaces / J. Burgdörfer ... [et al.]. Atomic collisions studied with "reaction-microscopes" / R. Moshammer ... [et al.]. Rydberg atoms: a microscale laboratory for studying electron-molecule tnteractions / F. B. Dunning -- Collisions involvintg photons. Quantum control of photochemical reaction dynamics and molecular functions / M. Yamaki ... [et al.]. Manipulating and viewing Rydberg wavepackets / R. R. Jones. Angle-resolved photoelectrons as a probe of strong-field interactions / M. Vrakking. Ultracold Rydberg atoms in a structured environment / I. C. H. Liu and J. M. Rost. Synchrotron-radiation-based recoil ion momentum spectroscopy of laser cooled and trapped cesium atoms / L. H. Coutinho. Reconstruction of attosecond pulse trains / Y. Mairesse ... [et al.]. Selective excitation of metastable atomic states by Femto- and attosecond laser pulses / A. D. Kondorskiy. Accurate calculations of triple differential cross sections for double photoionization of the hygrogen molecule / W. Vanroose ... [et al.]. Double and triple photoionization of Li and Be / J. Colgan, M. S. Pindzola and F. Robicheaux. Few/many body dynamics in strong laser fields / J. Zanghellini and T. Brabec. Rescattering-induced effects in electron-atom scattering in the presence of a circularly polarized laser field / A. V. Flegel ... [et al.]. Multidimensional photoelectron spectroscopy / P. Lablanquie ... [et al.]. Few photon and strongly driven transitions in the XUV and beyond / P. Lambropoulos, L. A. A. Nikolopoulos and S. I. Themelis. Ionization dynamics of atomic clusters in intense laser pulses / U. Saalmann and J. M. Rost. On the second order autocorrelation of an XUV attosecond pulse train / E. P. Benis ... [et al.]. Evidence for rescattering in molecular dissociation / I. D. Williams ... [et al.]. Photoionizing ions using synchrotron radiation / R. Phaneuf. Photo double

  17. Permeability of porous materials for liquid and gases

    NASA Astrophysics Data System (ADS)

    Krainov, V. P.; Smirnov, B. M.; Tereshonok, D. V.

    2014-11-01

    It is shown that propagation of liquids and gases through a porous material has a different character, namely, the viscosity characterizes this process for liquids, whereas for gases it is determined by collisions of the gas molecules with the skeleton of the porous material. The analog of the Kozeny-Carman formula in liquids for the Darcy coefficient or the permeability coefficient is represented for gases. The transition between these limiting cases results from the relation between the mean free path of an individual molecule in a liquid or gas λ and the mean free path of this molecule with respect to its scattering on the skeleton of a porous material.

  18. A numerical study on collisions of icy bodies using SPH method combined with GRAPE

    NASA Astrophysics Data System (ADS)

    Nakajima, M.; Genda, H.; Ida, S.

    2009-12-01

    We have worked on the collisions of icy bodies using Smoothed Particles Hydrodynamics (SPH) method combined with Gravity PipE (GRAPE) in order to understand the basic behavior of icy bodies during impacts. Collisions of Mars-size rocky bodies have been investigated well, because those collisions are related to the origin of the moon and the formation of the terrestrial planets. On the other hand, collisions of icy bodies have not been studied yet, although these collisions would frequently occur in the solar and extra-solar systems, such as the formation of icy exoplanets. Through our research, we figure out the effect of ice during impact in detail. Our SPH code has two special features. First, GRAvity PipE computer (GRAPE) is used, which calculates the gravitational force of each particle up to 100 times faster than usual computers. Second, SESAME equation of state database is used to build a realistic model, taking into account the effect of phase change. In this research, we focused on differences and similarities between collisions of icy bodies and those of rocky ones, such as a merging criterion. Agnor & Asphaug (2004) have shown that a collision of rocky Mars-size protoplanets leads to an inelastic collision when its relative velocities are smaller than 1.4-1.5v, 1.1-1.2v, 1.1-1.2v when its impact angles are 30, 45, and 60 degrees, respectively. Here, v means escape velocity. The same calculations for icy bodies are performed in our numerical code. They have shown that the merging criterion of icy bodies is the same as that of rocky bodies. In addition to the merging criterion, we also clarify the relationship between impact parameters and the change of solid, liquid/vapor mass ratio due to impacts.

  19. LIQUID TARGET

    DOEpatents

    Martin, M.D.; Salsig, W.W. Jr.

    1959-01-13

    A liquid handling apparatus is presented for a liquid material which is to be irradiated. The apparatus consists essentially of a reservoir for the liquid, a target element, a drain tank and a drain lock chamber. The target is in the form of a looped tube, the upper end of which is adapted to be disposed in a beam of atomic particles. The lower end of the target tube is in communication with the liquid in the reservoir and a means is provided to continuously circulate the liquid material to be irradiated through the target tube. Means to heat the reservoir tank is provided in the event that a metal is to be used as the target material. The apparatus is provided with suitable valves and shielding to provide maximum safety in operation.

  20. COLLIDE: Collisions into Dust Experiment

    NASA Technical Reports Server (NTRS)

    Colwell, Joshua E.

    1999-01-01

    The Collisions Into Dust Experiment (COLLIDE) was completed and flew on STS-90 in April and May of 1998. After the experiment was returned to Earth, the data and experiment were analyzed. Some anomalies occurred during the flight which prevented a complete set of data from being obtained. However, the experiment did meet its criteria for scientific success and returned surprising results on the outcomes of very low energy collisions into powder. The attached publication, "Low Velocity Microgravity Impact Experiments into Simulated Regolith," describes in detail the scientific background, engineering, and scientific results of COLLIDE. Our scientific conclusions, along with a summary of the anomalies which occurred during flight, are contained in that publication. We offer it as our final report on this grant.

  1. Practical Collisions for SHAMATA-256

    NASA Astrophysics Data System (ADS)

    Indesteege, Sebastiaan; Mendel, Florian; Preneel, Bart; Schläffer, Martin

    In this paper, we present a collision attack on the SHA-3 submission SHAMATA. SHAMATA is a stream cipher-like hash function design with components of the AES, and it is one of the fastest submitted hash functions. In our attack, we show weaknesses in the message injection and state update of SHAMATA. It is possible to find certain message differences that do not get changed by the message expansion and non-linear part of the state update function. This allows us to find a differential path with a complexity of about 296 for SHAMATA-256 and about 2110 for SHAMATA-512, using a linear low-weight codeword search. Using an efficient guess-and-determine technique we can significantly improve the complexity of this differential path for SHAMATA-256. With a complexity of about 240 we are even able to construct practical collisions for the full hash function SHAMATA-256.

  2. Simulated Ten Pin Bowling Collisions

    NASA Astrophysics Data System (ADS)

    Bills, Jacob; Howald, Craig

    2011-04-01

    This work investigates the results of the dynamics in the collisions that occur in ten pin bowling. A finite element modeling system (LS-Dyna) was used to construct simplified but approximately physically realistic models and simulate collisions involving the twelve body system composed of a ball, ten pins, and a floor. The investigation focuses on the qualitative features of the map of final pin configuration as a function of the initial conditions. To appropriately limit the breadth of the initial configuration space investigated, the only variables adjusted were the position of the ball upon entering the pins and the initial angle of velocity relative to the long axis of the lane. Results concerning the size and shape of the sets of initial conditions that lead to similar final configurations, in particular those leading to none of the pins remaining standing (aka "strikes"), are shown.

  3. Newton's cradle versus nonbinary collisions.

    PubMed

    Sekimoto, Ken

    2010-03-26

    Newton's cradle is a classical example of a one-dimensional impact problem. In the early 1980s the naive perception of its behavior was corrected: For example, the impact of a particle does not exactly cause the release of the farthest particle of the target particle train, if the target particles have been just in contact with their own neighbors. It is also known that the naive picture would be correct if the whole process consisted of purely binary collisions. Our systematic study of particle systems with truncated power-law repulsive force shows that the quasibinary collision is recovered in the limit of hard core repulsion, or a very large exponent. In contrast, a discontinuous steplike repulsive force mimicking a hard contact, or a very small exponent, leads to a completely different process: the impacting cluster and the targeted cluster act, respectively, as if they were nondeformable blocks.

  4. Central collisions of heavy ions

    SciTech Connect

    Fung, Sun-yiu.

    1992-10-01

    This report describes the activities of the Heavy Ion Physics Group at the University of California, Riverside from October 1, 1991 to September 30, 1992. During this period, the program focused on particle production at AGS energies, and correlation studies at the Bevalac in nucleus-nucleus central collisions. As part of the PHENIX collaboration, contributions were made to the Preliminary Conceptual Design Report (pCDR), and work on a RHIC silicon microstrip detector R D project was performed.

  5. The onset of cavitation during the collision of a sphere with a wetted surface

    NASA Astrophysics Data System (ADS)

    Mansoor, M. M.; Uddin, J.; Marston, J. O.; Vakarelski, I. U.; Thoroddsen, S. T.

    2014-01-01

    We investigate the onset of cavitation during the collision of a sphere with a solid surface covered with a layer of Newtonian liquid. The conventional theory dictates cavitation to initiate during depressurization, i.e. when the sphere rebounds from the solid surface. Using synchronized dual-view high-speed imaging, we provide conclusive experimental evidence that confirms this scenario—namely—that cavitation occurs only after the sphere makes initial contact with the solid surface. Similar to previous experimental observations for spheres released above the liquid surface, bubbles are formed on the sphere surface during entry into the liquid layer. These were found to squeeze radially outwards with the liquid flow as the sphere approached the solid surface, producing an annular bubble structure unrelated to cavitation. In contrast, spheres released below the liquid surface did not exhibit these patterns.

  6. QCD studies in ep collisions

    SciTech Connect

    Smith, W.H.

    1997-06-01

    These lectures describe QCD physics studies over the period 1992--1996 from data taken with collisions of 27 GeV electrons and positrons with 820 GeV protons at the HERA collider at DESY by the two general-purpose detectors H1 and ZEUS. The focus of these lectures is on structure functions and jet production in deep inelastic scattering, photoproduction, and diffraction. The topics covered start with a general introduction to HERA and ep scattering. Structure functions are discussed. This includes the parton model, scaling violation, and the extraction of F{sub 2}, which is used to determine the gluon momentum distribution. Both low and high Q{sup 2} regimes are discussed. The low Q{sup 2} transition from perturbative QCD to soft hadronic physics is examined. Jet production in deep inelastic scattering to measure {alpha}{sub s}, and in photoproduction to study resolved and direct photoproduction, is also presented. This is followed by a discussion of diffraction that begins with a general introduction to diffraction in hadronic collisions and its relation to ep collisions, and moves on to deep inelastic scattering, where the structure of diffractive exchange is studied, and in photoproduction, where dijet production provides insights into the structure of the Pomeron. 95 refs., 39 figs.

  7. Single Fusion Events at Polarized Liquid-Liquid Interfaces.

    PubMed

    Laborda, Eduardo; Molina, Angela; Espín, Vanesa Fernández; Martínez-Ortiz, Francisco; García de la Torre, José; Compton, Richard G

    2017-01-16

    A new electrochemical framework for tracking individual soft particles in solution and monitoring their fusion with polarized liquid-liquid interfaces is reported. The physicochemical principle lies in the interfacial transfer of an ionic probe confined in the particles dispersed in solution and that is released upon their collision and fusion with the fluid interface. As a proof-of-concept, spike-like transients of a stochastic nature are reported in the current-time response of 1,2-dichloroethane(DCE)|water(W) submilli-interfaces after injection of DCE-in-W emulsions. The sign and potential dependence of the spikes reflect the charge and lipophilicity of the ionic load of the droplets. A comparison with dynamic light scattering measurements indicates that each spike is associated with the collision of a single sub-picoliter droplet. This opens a new framework for the study of single fusion events at the micro- and nanoscale and of ion transport across biomimetic soft interfaces.

  8. Electron capture in ion-molecule collisions at intermediate energy

    SciTech Connect

    Kumura, M.

    1986-01-01

    Recent progress of theoretical charge transfer study in ion-molecule collisions at the intermediate energy is reviewed. Concept of close and distant collisions obtained from extensive ion-atom collision studies is identified so that it can be utilized to model two distinct collision processes. For a close collision, explicit representation of the whole collision complex is necessary to describe collision dynamics correctly, while a model potential approach for molecule is appropriate for a distant collision. It is shown that these two distinct models are indeed capable of reproducing experimental charge transfer cross sections. Some remarks for further theoretical study of ion-molecule collisions are also given. 21 refs., 8 figs.

  9. Collisions Between Rods: A Visual Analysis

    NASA Astrophysics Data System (ADS)

    Roura, Pere

    2003-01-01

    One of the key subjects in introductory physics is the problem of collisions. It provides a nice example where conservation laws of energy and momentum are essential. Two extreme cases are usually solved: elastic and perfectly inelastic collisions. In the very simple one-dimensional case, velocities before and after collision are readily related through the masses of the colliding bodies. Similar solutions can be found for partially inelastic collisions, provided that the degree of energy loss is known. Otherwise, the energy balance equation cannot be written down. Usually, one can reasonably assess whether the collision is perfectly inelastic (for instance, a bullet impinging onto a piece of wood). However, it is a matter of faith to consider a priori a collision as elastic or as being in any intermediate situation. We hope this statement will become clearer to the reader by the end of this paper.

  10. Analyzing Collisions in Terms of Newton's Laws

    NASA Astrophysics Data System (ADS)

    Roeder, John L.

    2003-02-01

    Although the principle of momentum conservation is a consequence of Newton's second and third laws of motion, as recognized by Newton himself, this principle is typically applied in analyzing collisions as if it is a separate concept of its own. This year I sought to integrate my treatment of collisions with my coverage of Newton's laws by asking students to calculate the effect on the motion of two particles due to the forces they exerted for a specified time interval on each other. For example, "A 50-kg crate slides across the ice at 3 m/s and collides with a 25-kg crate at rest. During the collision process the 50-kg crate exerts a 500 N time-averaged force on the 25 kg for 0.1 s. What are the accelerations of the crates during the collision, and what are their velocities after the collision? What are the momenta of the crates before and after collision?"

  11. A Collective Collision Operator for DSMC

    SciTech Connect

    GALLIS,MICHAIL A.; TORCZYNSKI,JOHN R.

    2000-06-21

    A new scheme to simulate elastic collisions in particle simulation codes is presented. The new scheme aims at simulating the collisions in the highly collisional regime, in which particle simulation techniques typically become computationally expensive.The new scheme is based on the concept of a grid-based collision field. According to this scheme, the particles perform a single collision with the background grid during a time step. The properties of the background field are calculated from the moments of the distribution function accumulated on the grid. The collision operator is based on the Langevin equation. Based on comparisons with other methods, it is found that the Langevin method overestimates the collision frequency for dilute gases.

  12. Reactive collision terms for fluid transport theory

    NASA Technical Reports Server (NTRS)

    Eccles, J. V.; Raitt, W. J.

    1992-01-01

    A modified Bhatnagar-Gross-Krook (BGK) collision method is used for the derivation of reactive collision terms to allow for complete higher-moment approximations in fluid transport theory. The general reactive collision terms for the 8-, 10- and 13-moment approximation for binary reactions are derived. Then, reactive collision terms for specific chemistry are derived with the assumptions: (1) all reactants and products have 13-moment distribution functions; (2) simple, classical assumptions provide sufficient models for reaction dynamics; and (3) the reaction rate is energy-independent. The derived specific formulas reflect two extremes in reactive collision dynamics: direct and indirect reaction mechanisms. Finally, considerations for correct use of the reactive collision terms are discussed in the context of space plasma environments.

  13. Fraction of space debris collisions that are catastrophic

    SciTech Connect

    Canavan, G.H.

    1996-08-01

    Analytic calculations estimate the fraction of catalog collisions that are catastrophic by a modification of collision rates. Most catalog collisions are catastrophic. Impactors of 60 kg or larger participate in about half of the catastrophic collisions. Analytic estimates give accurate values for catastrophic collisions, which are complicated numerically.

  14. Liquid penetrants

    NASA Technical Reports Server (NTRS)

    Pasley, R. L.

    1973-01-01

    Liquid-penetrant inspection is discussed for surface defects in solids. The principle advantages are considered to be its simplicity and economy. The techniques and penetrants are described along with the developers. Commercially available equipment is also described.

  15. Experimental Study of the Effects of Collision of Water Droplets in a Flow of High-Temperature Gases

    NASA Astrophysics Data System (ADS)

    Antonov, D. V.; Volkov, R. S.; Kuznetsov, G. V.; Strizhak, P. A.

    2016-01-01

    Using high-speed video recording and cross-correlation "tracer" visualization, the authors have investigated the regularities of the processes of collision of water droplets (characteristic parameters: radii 0.025-0.25 mm, velocities of motion 0.5-12 m/s, and relative concentration 0.001-0.0012 m3 of liquid droplets in 1 m3 of the gas) in their motion in a flow of high-temperature (about 1100 K) gases. The characteristic effects of collision of two droplets, at which combined droplets are formed (coagulation occurs) and conditions for spreading or fragmentation of the latter are implemented, have been singled out. The values of the Weber and Reynolds numbers for droplets before and after the collisions have been established. The influences of the velocities of motion, the dimensions, and the angles of intersection of mechanical trajectories of droplets on the effects of collisions have been determined.

  16. Conservative Bin-to-Bin Fractional Collisions

    DTIC Science & Technology

    2016-06-28

    UNLIMITED; PA #16326 6 / 18 SWPM COLLISIONS Stochastic Weighted Particle Method: Developed by Rjasanow & Wagner Attempted Collisions/Cell: ν = f (2w̄...Developed by Rjasanow & Wagner Adapted as Modified NTC/MCF Attempted Collisions/Cell: ν = f (2w̄−wmin)Np(Np − 1) 〈σv〉 max dt Select Pair (i,j) if: Rand...DISTRIBUTION UNLIMITED; PA #16326 7 / 18 SWPM COLLISIONS Stochastic Weighted Particle Method: Developed by Rjasanow & Wagner Adapted as Modified NTC

  17. Telerobotics with whole arm collision avoidance

    SciTech Connect

    Wilhelmsen, K.; Strenn, S.

    1993-09-01

    The complexity of teleorbotic operations in a cluttered environment is exacerbated by the need to present collision information to the operator in an understandable fashion. In addition to preventing movements which will cause collisions, a system providing some form of virtual force reflection (VFR) is desirable. With this goal in mind, Lawrence Livermore National Laboratory (LLNL) has installed a kinematically master/slave system and developed a whole arm collision avoidance system which interacts directly with the telerobotic controller. LLNL has also provided a structure to allow for automated upgrades of workcell models and provide collision avoidance even in a dynamically changing workcell.

  18. Origin of collision-induced molecular orientation.

    PubMed

    Brouard, M; Hornung, B; Aoiz, F J

    2013-11-01

    Collision-induced rotational angular momentum orientation is a fundamental property of molecular scattering, which is sensitive to the balance between attractive and repulsive forces at play during collision. Here, we quantify a new mechanism leading to orientation, which is purely quantum mechanical in origin. Although the new mechanism is quite general, and will operate more widely in atomic and molecular scattering, it is observed here for impulsive hard shell collisions, for which the orientation vanishes classically. The quantum mechanism can thus be studied in isolation from other processes. The orientation is proposed to originate from the nonlocal nature of the quantum mechanical collision encounter.

  19. Integrated Collision Avoidance System for Air Vehicle

    NASA Technical Reports Server (NTRS)

    Lin, Ching-Fang (Inventor)

    2013-01-01

    Collision with ground/water/terrain and midair obstacles is one of the common causes of severe aircraft accidents. The various data from the coremicro AHRS/INS/GPS Integration Unit, terrain data base, and object detection sensors are processed to produce collision warning audio/visual messages and collision detection and avoidance of terrain and obstacles through generation of guidance commands in a closed-loop system. The vision sensors provide more information for the Integrated System, such as, terrain recognition and ranging of terrain and obstacles, which plays an important role to the improvement of the Integrated Collision Avoidance System.

  20. Flight Tests Validate Collision-Avoidance System

    NASA Image and Video Library

    Flights tests of a smartphone-assisted automatic ground collision avoidance system at NASA's Dryden Flight Research Center consistently commanded evasive maneuvers when it sensed that the unmanned ...

  1. PREFACE: Functionalized Liquid Liquid Interfaces

    NASA Astrophysics Data System (ADS)

    Girault, Hubert; Kornyshev, Alexei A.; Monroe, Charles W.; Urbakh, Michael

    2007-09-01

    Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a number of distinctive features. Both sides of the interface are amenable to detailed physical and chemical analysis. By chemical or electrochemical means, metal or semiconductor nanoparticles can be formed or localised at the interface. Surfactants can be used to tailor surface properties, and also to place organic molecular or supermolecular constructions at the boundary between the liquids. Electric fields can be used to drive ions from one fluid to another, or even change the shape of the interface itself. In many cases, both liquids are optically transparent, making functionalized liquid-liquid interfaces promising for various optical applications based on the transmission or reflection of light. An advantage common to most of these systems is self-assembly; because a liquid-liquid interface is not mechanically constrained like a solid-liquid interface, it can easily access its most stable state, even after it has been driven far from equilibrium. This special issue focuses on four modes of liquid-liquid interfacial functionalization: the controlled adsorption of molecules or nanoparticles, the formation of adlayers or films, electrowetting, and ion transfer or interface-localized reactions. Interfacial adsorption can be driven electrically, chemically, or mechanically. The liquid-liquid interface can be used to study how anisotropic particles orient at a surface under the influence of a field, how surfactants interact with other adsorbates, and how nanoparticles aggregate; the transparency of the interface also makes the chirality of organic adsorbates amenable to

  2. Collinear Collision Chemistry: 1. A Simple Model for Inelastic and Reactive Collision Dynamics

    ERIC Educational Resources Information Center

    Mahan, Bruce H.

    1974-01-01

    Discusses a model for the collinear collision of an atom with a diatomic molecule on a simple potential surface. Indicates that the model can provide a framework for thinking about molecular collisions and reveal many factors which affect the dynamics of reactive and inelastic collisions. (CC)

  3. An introductory analysis of satellite collision probabilities

    NASA Astrophysics Data System (ADS)

    Carlton-Wippern, Kitt C.

    This paper addresses a probailistic approach in assessing the probabilities of a satellite collision occurring due to relative trajectory analyses and probability density functions representing the satellites' position/momentum vectors. The paper is divided into 2 parts: Static and Dynamic Collision Probabilities. In the Static Collision Probability section, the basic phenomenon under study is: given the mean positions and associated position probability density functions for the two objects, calculate the probability that the two objects collide (defined as being within some distance of each other). The paper presents the classic Laplace problem of the probability of arrival, using standard uniform distribution functions. This problem is then extrapolated to show how 'arrival' can be classified as 'collision', how the arrival space geometries map to collision space geometries and how arbitrary position density functions can then be included and integrated into the analysis. In the Dynamic Collision Probability section, the nature of collisions based upon both trajectory and energy considerations is discussed, and that energy states alone cannot be used to completely describe whether or not a collision occurs. This fact invalidates some earlier work on the subject and demonstrates why Liouville's theorem cannot be used in general to describe the constant density of the position/momentum space in which a collision may occur. Future position probability density functions are then shown to be the convolution of the current position and momentum density functions (linear analysis), and the paper further demonstrates the dependency of the future position density functions on time. Strategies for assessing the collision probabilities for two point masses with uncertainties in position and momentum at some given time, and thes integrated with some arbitrary impact volume schema, are then discussed. This presentation concludes with the formulation of a high level design

  4. Liquid Crystals

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  5. Positron collisions with alkali-metal atoms

    NASA Technical Reports Server (NTRS)

    Gien, T. T.

    1990-01-01

    The total cross sections for positron and electron collisions with potassium, sodium, lithium and rubidium are calculated, employing the modified Glauber approximation. The Modified Glauber cross sections for positron collision with potassium and sodium at low intermediate energies are found to agree reasonably well with existing experimental data.

  6. Oblique and Head-On Elastic Collisions

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2008-01-01

    When a moving ball collides elastically with an identical, initially stationary ball, the incident ball will either come to rest (head-on collision; see Fig. 1) or will acquire a velocity that is perpendicular to that acquired by the target ball (oblique collision; see Fig. 2). These two possible outcomes are related in an interesting way, which…

  7. Charge exchange in H^+ + He^+ collision

    NASA Astrophysics Data System (ADS)

    Guevara Leon, Nicolais; Sabin, John R.; Deumens, Erik; Ohrn, Yngve

    2008-05-01

    Charge exchange in H^+ + He^+ collision are investigated theoretically at projectile energies below the ionization threshold at about 100 keV/amu. The electron nuclear dynamics (END) method is used to analyze the collision processes. Total charge exchange cross sections were calculated and compared with other theoretical and experimental data.

  8. 46 CFR 171.085 - Collision bulkhead.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the collision bulkhead must be at least— (1) 5 percent of the LBP from the forward perpendicular in a motor vessel; and (2) 5 feet (1.52 meters) from the forward perpendicular in a steam vessel. (d) The collision bulkhead must be no more than 10 feet (3 meters) plus 5 percent of the LBP from the forward...

  9. 46 CFR 171.085 - Collision bulkhead.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the collision bulkhead must be at least— (1) 5 percent of the LBP from the forward perpendicular in a motor vessel; and (2) 5 feet (1.52 meters) from the forward perpendicular in a steam vessel. (d) The collision bulkhead must be no more than 10 feet (3 meters) plus 5 percent of the LBP from the forward...

  10. 46 CFR 171.085 - Collision bulkhead.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the collision bulkhead must be at least— (1) 5 percent of the LBP from the forward perpendicular in a motor vessel; and (2) 5 feet (1.52 meters) from the forward perpendicular in a steam vessel. (d) The collision bulkhead must be no more than 10 feet (3 meters) plus 5 percent of the LBP from the forward...

  11. Mechanical Energy Changes in Perfectly Inelastic Collisions

    ERIC Educational Resources Information Center

    Mungan, Carl E.

    2013-01-01

    Suppose a block of mass "m"[subscript 1] traveling at speed "v"[subscript 1] makes a one-dimensional perfectly inelastic collision with another block of mass "m"[subscript 2]. What else does one need to know to calculate the fraction of the mechanical energy that is dissipated in the collision? (Contains 1 figure.)

  12. Oblique and Head-On Elastic Collisions

    ERIC Educational Resources Information Center

    Ng, Chiu-king

    2008-01-01

    When a moving ball collides elastically with an identical, initially stationary ball, the incident ball will either come to rest (head-on collision; see Fig. 1) or will acquire a velocity that is perpendicular to that acquired by the target ball (oblique collision; see Fig. 2). These two possible outcomes are related in an interesting way, which…

  13. Cultural Collisions in L2 Academic Writing.

    ERIC Educational Resources Information Center

    Steinman, Linda

    2003-01-01

    Reviews research on writing and culture, focusing on the collisions of cultures when discourse practices second language writers are expected to reproduce clash with what they know, believe, and value in their first language writing. Describes collisions of culture in writing regarding voice, organization, reader/writer responsibility, topic, and…

  14. Collision risk management in geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Jenkin, A. B.; Peterson, G. E.

    2004-01-01

    A systematic method has been developed for managing long-term collision risk posed to operational satellites in geosynchronous orbit. Long-term collision risk reduction is achieved by proper selection of local collision probability thresholds that trigger actions to reduce risk. Such actions can be requests for more accurate orbital data, special sensor tasking, or collision avoidance maneuvers. The cost of collision risk reduction is measured by the frequency of actions taken to reduce the collision risk. This action frequency is dependent on the accuracy of the orbital data and the frequency of close approaches. A case study was performed for a set of satellites. The analysis used position error models for two-line element sets. A conjunction simulation was used to process approximately three years of archived orbital data, including publicly available two-line element sets, in order to generate conjunction statistics. From these results, a graphical representation called a χ-plot was generated. This plot permits the selection of thresholds as a function of total risk reduction and tolerable action frequency. Results of the study indicate that collision risk management in geosynchronous orbit can be very costly using data of insufficiently high accuracy, because data errors induce high action frequency for even modest amounts of collision risk reduction.

  15. Mechanical Energy Changes in Perfectly Inelastic Collisions

    ERIC Educational Resources Information Center

    Mungan, Carl E.

    2013-01-01

    Suppose a block of mass "m"[subscript 1] traveling at speed "v"[subscript 1] makes a one-dimensional perfectly inelastic collision with another block of mass "m"[subscript 2]. What else does one need to know to calculate the fraction of the mechanical energy that is dissipated in the collision? (Contains 1 figure.)

  16. Fixed Target Collisions at STAR

    NASA Astrophysics Data System (ADS)

    Meehan, Kathryn C.

    2016-12-01

    The RHIC Beam Energy Scan (BES) program was proposed to look for the turn-off of signatures of the quark gluon plasma (QGP), search for a possible QCD critical point, and study the nature of the phase transition between hadronic and partonic matter. Previous results have been used to claim that the onset of deconfinement occurs at a center-of-mass energy of 7 GeV. Data from lower energies are needed to test if this onset occurs. The goal of the STAR Fixed-Target Program is to extend the collision energy range in BES II to energies that are likely below the onset of deconfinement. Currently, STAR has inserted a gold target into the beam pipe and conducted test runs at center-of-mass energies of 3.9 and 4.5 GeV. Tests have been done with both Au and Al beams. First physics results from a Coulomb potential analysis of Au + Au fixed-target collisions are presented and are found to be consistent with results from previous experiments. Furthermore, the Coulomb potential, which is sensitive to the Z of the projectile and degree of baryonic stopping, will be compared to published results from the AGS.

  17. Energy coupling in catastrophic collisions

    NASA Technical Reports Server (NTRS)

    Holsapple, K. A.; Choe, K. Y.

    1991-01-01

    The prediction of events leading to the catastrophic collisions and disruption of solar system bodies is fraught with the same difficulties as are other theories of impact events; since one simply cannot perform experiments in the regime of interest. In the catastrophic collisions of asteroids that regime involves bodies of a few tons to hundred of kilometers in diameter, and velocities of several kilometers pre second. For hundred kilometer bodies, gravitational stresses dominate material fracture strengths, but those gravitational stresses are essentially absent for laboratory experiments. Only numerical simulations using hydrocodes can in principle analyze the true problems, but they have their own major uncertainties about the correctness of the physical models and properties. The question of the measure of the impactor and its energy coupling is investigated using numerical code calculations. The material model was that of a generic silicate rock, including high pressure melt and vapor phases, and includes material nonlinearity and dissipation via a Mie-Gruniesen model. A series of calculations with various size ratios and impact velocities are reported.

  18. Simulating Collisions for Hydrokinetic Turbines

    SciTech Connect

    Richmond, Marshall C.; Romero Gomez, Pedro DJ; Rakowski, Cynthia L.

    2013-10-01

    Evaluations of blade-strike on an axial-flow Marine Hydrokinetic turbine were conducted using a conventional methodology as well as an alternative modeling approach proposed in the present document. The proposed methodology integrates the following components into a Computa- tional Fluid Dynamics (CFD) model: (i) advanced eddy-resolving flow simulations, (ii) ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimic the potential fish pathways. The sensitivity of blade-strike prob- ability to the following conditions was also evaluated: (i) to the turbulent environment, (ii) to fish size and (iii) to mean stream flow velocity. The proposed methodology provided fraction of collisions and offered the capability of analyzing the causal relationships between the flow envi- ronment and resulting strikes on rotating blades. Overall, the conventional methodology largely overestimates the probability of strike, and lacks the ability to produce potential fish and aquatic biota trajectories as they interact with the rotating turbine. By using a set of experimental corre- lations of exposure-response of living fish colliding on moving blades, the occurrence, frequency and intensity of the particle collisions was next used to calculate the survival rate of fish crossing the MHK turbine. This step indicated survival rates always greater than 98%. Although the proposed CFD framework is computationally more expensive, it provides the advantage of evaluating multiple mechanisms of stress and injury of hydrokinetic turbine devices on fish.

  19. Ground Collision Avoidance System (Igcas)

    NASA Technical Reports Server (NTRS)

    Skoog, Mark A (Inventor); Prosser, Kevin (Inventor); Hook, Loyd (Inventor)

    2017-01-01

    The present invention is a system and method for aircraft ground collision avoidance (iGCAS) comprising a modular array of software, including a sense own state module configured to gather data to compute trajectory, a sense terrain module including a digital terrain map (DTM) and map manger routine to store and retrieve terrain elevations, a predict collision threat module configured to generate an elevation profile corresponding to the terrain under the trajectory computed by said sense own state module, a predict avoidance trajectory module configured to simulate avoidance maneuvers ahead of the aircraft, a determine need to avoid module configured to determine which avoidance maneuver should be used, when it should be initiated, and when it should be terminated, a notify Module configured to display each maneuver's viability to the pilot by a colored GUI, a pilot controls module configured to turn the system on and off, and an avoid module configured to define how an aircraft will perform avoidance maneuvers through 3-dimensional space.

  20. Molecular collisions coming into focus.

    PubMed

    Onvlee, Jolijn; Vogels, Sjoerd N; von Zastrow, Alexander; Parker, David H; van de Meerakker, Sebastiaan Y T

    2014-08-14

    The Stark deceleration method exploits the concepts of charged particle accelerator physics to produce beams of neutral polar molecules with an almost perfect quantum state purity, a tunable velocity and a narrow velocity distribution. These monochromatic molecular beams offer interesting perspectives for precise studies of molecular scattering processes, in particular when used in conjunction with state-of-the-art laser-based detection techniques such as velocity map imaging. Here, we describe crossed beam scattering experiments in which the Stark deceleration method is combined with the velocity map imaging technique. The narrow velocity spread of Stark-decelerated molecular beams results in scattering images with unprecedented velocity and angular resolution. We demonstrate this by resolving quantum diffraction oscillations in state-to-state inelastic differential scattering cross sections for collisions between NO radicals and rare gas atoms. We describe the future prospects of this "best-of-two-worlds" combination, ranging from scattering studies at low collision energies to bimolecular scattering using two decelerators, and discuss the challenges that lie ahead to achieve these goals.

  1. Collisions of noble gases with supercooled sulfuric acid-water solutions.

    PubMed

    Behr, Peter; Scharfenort, Ulrich; Zellner, Reinhard

    2009-09-07

    The collisions of hyperthermal noble gases (He, Ne, Ar, Kr, Xe) with supercooled binary sulfuric acid-water mixtures (57-77 wt%) were explored in the temperature range between 210 and 240 K. The experiments were performed by directing a molecular beam of the respective gases onto a continuously renewed liquid surface and monitoring the velocity of the scattered molecules by mass spectrometry. Depending on the initial translational energies and molecular masses, we observe both inelastic scattering from the surface as well as thermalization followed by subsequent desorption. The experiments indicate that the repulsive momentum transfer in the inelastic scattering channel increases with increasing mass of the impinging gas, while it is only weakly affected by the initial velocities. The final energy of the thermally desorbing atoms can always be approximated by a Maxwell-Boltzmann distribution equal to the liquid bulk phase temperature. The influence of the binary composition of the liquid phase is only noticeable in the case of Ne, whilst this dependence diminishes for gases with molecular masses >or=40 amu. The probability of thermalisation relative to inelastic scattering increases with the bulk phase temperature, independent of the molecular masses of the colliding gas. In contrast, the fractional energy transfer during collision does not increase with temperature, except for Neon. These results can be interpreted in the model framework of hard-sphere collisions of noble gases with the surface, during which water and sulfuric acid molecules interact independently with the impinging gas.

  2. Macromolecular liquids

    SciTech Connect

    Safinya, C.R.; Safran, S.A. ); Pincus, P.A. )

    1990-01-01

    Liquids include a broad range of material systems which are of high scientific and technological interest. Generally speaking, these are partially ordered or disordered phases where the individual molecular species have organized themselves on length scales which are larger than simple fluids, typically between 10 Angstroms and several microns. The specific systems reported on in this book include membranes, microemulsions, micelles, liquid crystals, colloidal suspensions, and polymers. They have a major impact on a broad spectrum of technological industries such as displays, plastics, soap and detergents, chemicals and petroleum, and pharmaceuticals.

  3. Experiments with large diameter gravity driven impacting liquid jets

    NASA Astrophysics Data System (ADS)

    Storr, G. J.; Behnia, M.

    The phenomenon of a liquid jet released under gravity and falling through or impacting onto another liquid before colliding with an obstructing solid surface has been studied experimentally under isothermal conditions. Usually the jet diameter was sufficiently large to ensure jet coherency until collision. Direct flow visualization was used to study jets released into water pools with no air head space and jets impacting onto water pools after falling through an air head space. It is shown that distances predicting the onset of buoyancy and the entrainment of air using derivations from continuous plunging jets, are not applicable for impacting jets. The morphology of jet debris after collision with the solid surfaces correlates with the wetting properties of the jet liquid on the surface.

  4. Liquid ventilation

    PubMed Central

    Sarkar, Suman; Paswan, Anil; Prakas, S.

    2014-01-01

    Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported. PMID:25886321

  5. Basins in ARC-continental collisions

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Busby, Cathy; Azor, Antonio

    2012-01-01

    Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

  6. Stokes's Cradle: Newton's Cradle with Liquid Coating

    NASA Astrophysics Data System (ADS)

    Donahue, C. M.; Hrenya, C. M.; Davis, R. H.

    2010-07-01

    Granular flows involving liquid-coated solids are ubiquitous in nature (pollen capture, avalanches) and industry (filtration, pharmaceutical mixing). In this Letter, three-body collisions between liquid-coated spheres are investigated experimentally using a “Stokes’s cradle,” which resembles the popular desktop toy Newton’s cradle (NC). Surprisingly, previous work shows that every possible outcome was observed in the Stokes’s cradle except the traditional NC outcome. Here, we experimentally achieve NC via guidance from a theory, which revealed that controlling the liquid-bridge volume connecting two target particles is the key in attaining the NC outcome. These three-body experiments also provide direct evidence that the fluid resistance upon rebound cannot be completely neglected due to presumed cavitation; this resistance also influences two-body systems yet cannot be isolated experimentally in such systems.

  7. Stokes's cradle: Newton's cradle with liquid coating.

    PubMed

    Donahue, C M; Hrenya, C M; Davis, R H

    2010-07-16

    Granular flows involving liquid-coated solids are ubiquitous in nature (pollen capture, avalanches) and industry (filtration, pharmaceutical mixing). In this Letter, three-body collisions between liquid-coated spheres are investigated experimentally using a "Stokes's cradle," which resembles the popular desktop toy Newton's cradle (NC). Surprisingly, previous work shows that every possible outcome was observed in the Stokes's cradle except the traditional NC outcome. Here, we experimentally achieve NC via guidance from a theory, which revealed that controlling the liquid-bridge volume connecting two target particles is the key in attaining the NC outcome. These three-body experiments also provide direct evidence that the fluid resistance upon rebound cannot be completely neglected due to presumed cavitation; this resistance also influences two-body systems yet cannot be isolated experimentally in such systems.

  8. Restricted Collision List method for faster Direct Simulation Monte-Carlo (DSMC) collisions

    NASA Astrophysics Data System (ADS)

    Macrossan, Michael N.

    2016-08-01

    The 'Restricted Collision List' (RCL) method for speeding up the calculation of DSMC Variable Soft Sphere collisions, with Borgnakke-Larsen (BL) energy exchange, is presented. The method cuts down considerably on the number of random collision parameters which must be calculated (deflection and azimuthal angles, and the BL energy exchange factors). A relatively short list of these parameters is generated and the parameters required in any cell are selected from this list. The list is regenerated at intervals approximately equal to the smallest mean collision time in the flow, and the chance of any particle re-using the same collision parameters in two successive collisions is negligible. The results using this method are indistinguishable from those obtained with standard DSMC. The CPU time saving depends on how much of a DSMC calculation is devoted to collisions and how much is devoted to other tasks, such as moving particles and calculating particle interactions with flow boundaries. For 1-dimensional calculations of flow in a tube, the new method saves 20% of the CPU time per collision for VSS scattering with no energy exchange. With RCL applied to rotational energy exchange, the CPU saving can be greater; for small values of the rotational collision number, for which most collisions involve some rotational energy exchange, the CPU may be reduced by 50% or more.

  9. A method of inferring collision ratio based on maneuverability of own ship under critical collision conditions

    NASA Astrophysics Data System (ADS)

    You, Youngjun; Rhee, Key-Pyo; Ahn, Kyoungsoo

    2013-06-01

    In constructing a collision avoidance system, it is important to determine the time for starting collision avoidance maneuver. Many researchers have attempted to formulate various indices by applying a range of techniques. Among these indices, collision risk obtained by combining Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) information with fuzzy theory is mostly used. However, the collision risk has a limit, in that membership functions of DCPA and TCPA are empirically determined. In addition, the collision risk is not able to consider several critical collision conditions where the target ship fails to take appropriate actions. It is therefore necessary to design a new concept based on logical approaches. In this paper, a collision ratio is proposed, which is the expected ratio of unavoidable paths to total paths under suitably characterized operation conditions. Total paths are determined by considering categories such as action space and methodology of avoidance. The International Regulations for Preventing Collisions at Sea (1972) and collision avoidance rules (2001) are considered to solve the slower ship's dilemma. Different methods which are based on a constant speed model and simulated speed model are used to calculate the relative positions between own ship and target ship. In the simulated speed model, fuzzy control is applied to determination of command rudder angle. At various encounter situations, the time histories of the collision ratio based on the simulated speed model are compared with those based on the constant speed model.

  10. Restricted Collision List method for faster Direct Simulation Monte-Carlo (DSMC) collisions

    SciTech Connect

    Macrossan, Michael N.

    2016-08-15

    The ‘Restricted Collision List’ (RCL) method for speeding up the calculation of DSMC Variable Soft Sphere collisions, with Borgnakke–Larsen (BL) energy exchange, is presented. The method cuts down considerably on the number of random collision parameters which must be calculated (deflection and azimuthal angles, and the BL energy exchange factors). A relatively short list of these parameters is generated and the parameters required in any cell are selected from this list. The list is regenerated at intervals approximately equal to the smallest mean collision time in the flow, and the chance of any particle re-using the same collision parameters in two successive collisions is negligible. The results using this method are indistinguishable from those obtained with standard DSMC. The CPU time saving depends on how much of a DSMC calculation is devoted to collisions and how much is devoted to other tasks, such as moving particles and calculating particle interactions with flow boundaries. For 1-dimensional calculations of flow in a tube, the new method saves 20% of the CPU time per collision for VSS scattering with no energy exchange. With RCL applied to rotational energy exchange, the CPU saving can be greater; for small values of the rotational collision number, for which most collisions involve some rotational energy exchange, the CPU may be reduced by 50% or more.

  11. Maxillofacial injuries in moose-motor vehicle collisions versus other high-speed motor vehicle collisions

    PubMed Central

    Kim, Sharon; Harrop, A Robertson

    2005-01-01

    BACKGROUND: Anecdotal experience has suggested that there is a higher frequency of maxillofacial injuries among motor vehicle collisions involving moose. OBJECTIVES: A retrospective cohort study design was used to investigate the incidence of various injuries resulting from moose-motor vehicle collisions versus other high-speed motor vehicle collisions. METHODS: A chart review was conducted among patients presenting to a Canadian regional trauma centre during the five-year period from 1996 to 2000. RESULTS: Fifty-seven moose-motor vehicle collisions were identified; 121 high-speed collisions were randomly selected as a control group. Demographic, collision and injury data were collected from these charts and statistically analyzed. The general demographic features of the two groups were similar. Moose collisions were typically frontal impact resulting in windshield damage. The overall injury severity was similar in both groups. Likewise, the frequency of intracranial, spinal, thoracic and extremity injuries was similar for both groups. The group involved in collisions with moose, however, was 1.8 times more likely then controls to sustain a maxillofacial injury (P=0.004) and four times more likely to sustain a maxillofacial fracture (P=0.006). CONCLUSIONS: Occupants of motor vehicles colliding with moose are more likely to sustain maxillofacial injuries than those involved in other types of motor vehicle collisions. It is speculated that this distribution of injuries relates to the mechanism of collision with these large mammals with a high centre of gravity. PMID:24227930

  12. Continuum modeling of catastrophic collisions

    NASA Technical Reports Server (NTRS)

    Ryan, Eileen V.; Aspaug, Erik; Melosh, H. J.

    1991-01-01

    A two dimensional hydrocode based on 2-D SALE was modified to include strength effects and fragmentation equations for fracture resulting from tensile stress in one dimension. Output from this code includes a complete fragmentation summary for each cell of the modeled object: fragment size (mass) distribution, vector velocities of particles, peak values of pressure and tensile stress, and peak strain rates associated with fragmentation. Contour plots showing pressure and temperature at given times within the object are also produced. By invoking axial symmetry, three dimensional events can be modeled such as zero impact parameter collisions between asteroids. The code was tested against the one dimensional model and the analytical solution for a linearly increasing tensile stress under constant strain rate.

  13. Heavy ion collisions and cosmology

    NASA Astrophysics Data System (ADS)

    Floerchinger, Stefan

    2016-12-01

    There are interesting parallels between the physics of heavy ion collisions and cosmology. Both systems are out-of-equilibrium and relativistic fluid dynamics plays an important role for their theoretical description. From a comparison one can draw interesting conclusions for both sides. For heavy ion physics it could be rewarding to attempt a theoretical description of fluid perturbations similar to cosmological perturbation theory. In the context of late time cosmology, it could be interesting to study dissipative properties such as shear and bulk viscosity and corresponding relaxation times in more detail. Knowledge and experience from heavy ion physics could help to constrain the microscopic properties of dark matter from observational knowledge of the cosmological fluid properties.

  14. Data for modeling of positron collisions and transport in gases

    NASA Astrophysics Data System (ADS)

    Petrović, Z. Lj.; Banković, A.; Dujko, S.; Marjanović, S.; Malović, G.; Sullivan, J. P.; Buckman, S. J.

    2013-07-01

    We review the current status of positron cross sections for collisions with atoms and molecules from the viewpoint of their use in studies of positron transport processes in gases, liquids and human tissue. The data include cross sections for positron scattering in rare gases, molecular gases (eg., for N2, H2, CO2, CF4) and in particular for organic molecules and those relevant for applications in medicine (e.g. formic acid and water vapor). The cross sections were taken from an assessment of previously published positron-target cross sections. All of the cross sections are based on binary collision measurements and theoretical calculations, and they were not explicitly modified according to the standard swarm analysis. The main reason for this is systematic lack of experimental data for positron transport properties in gases. However, we believe that our compiled sets of cross sections are at level of sophistication, and of sufficient accuracy, to provide correct interpretation of future positron-based experiments. Using these cross sections as an input in our Monte Carlo simulations and Boltzmann equation treatment, we review some interesting points observed in the profiles of various transport coefficients for positrons in gases. Particular emphasis is placed upon the analysis of kinetic phenomena generated by the explicit influence of Ps formation.

  15. Thermally induced collision of droplets in an immiscible outer fluid

    NASA Astrophysics Data System (ADS)

    Davanlou, Ashkan; Kumar, Ranganathan

    2015-05-01

    Micro-total analysis systems (μTAS) have attracted wide attention and are identified as a promising solution for sample transport, filtration, chemical reactions, separation and detection. Despite their popularity, the selection of an appropriate mechanism for droplet transport and coalescence has always been a challenge. This paper investigates the use of Marangoni flow as a mechanism for levitating and transporting droplets on immiscible liquid films at higher speeds than is possible currently. For the first time, we show that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of shape and size on collision outcome are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. In addition, the effect of viscosity on post collision regimes is studied. The findings in this fundamental study can be beneficial to many applications such as welding, drug delivery and microfluidics devices in controlling small droplets and targeting them to various locations.

  16. Thermally induced collision of droplets in an immiscible outer fluid.

    PubMed

    Davanlou, Ashkan; Kumar, Ranganathan

    2015-05-07

    Micro-total analysis systems (μTAS) have attracted wide attention and are identified as a promising solution for sample transport, filtration, chemical reactions, separation and detection. Despite their popularity, the selection of an appropriate mechanism for droplet transport and coalescence has always been a challenge. This paper investigates the use of Marangoni flow as a mechanism for levitating and transporting droplets on immiscible liquid films at higher speeds than is possible currently. For the first time, we show that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of shape and size on collision outcome are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. In addition, the effect of viscosity on post collision regimes is studied. The findings in this fundamental study can be beneficial to many applications such as welding, drug delivery and microfluidics devices in controlling small droplets and targeting them to various locations.

  17. Thermally induced collision of droplets in an immiscible outer fluid

    PubMed Central

    Davanlou, Ashkan; Kumar, Ranganathan

    2015-01-01

    Micro-total analysis systems (μTAS) have attracted wide attention and are identified as a promising solution for sample transport, filtration, chemical reactions, separation and detection. Despite their popularity, the selection of an appropriate mechanism for droplet transport and coalescence has always been a challenge. This paper investigates the use of Marangoni flow as a mechanism for levitating and transporting droplets on immiscible liquid films at higher speeds than is possible currently. For the first time, we show that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of shape and size on collision outcome are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. In addition, the effect of viscosity on post collision regimes is studied. The findings in this fundamental study can be beneficial to many applications such as welding, drug delivery and microfluidics devices in controlling small droplets and targeting them to various locations. PMID:25948547

  18. CHARACTERIZATION OF WILD PIG VEHICLE COLLISIONS

    SciTech Connect

    Mayer, J; Paul E. Johns, P

    2007-05-23

    Wild pig (Sus scrofa) collisions with vehicles are known to occur in the United States, but only minimal information describing these accidents has been reported. In an effort to better characterize these accidents, data were collected from 179 wild pig-vehicle collisions from a location in west central South Carolina. Data included accident parameters pertaining to the animals involved, time, location, and human impacts. The age structure of the animals involved was significantly older than that found in the population. Most collisions involved single animals; however, up to seven animals were involved in individual accidents. As the number of animals per collision increased, the age and body mass of the individuals involved decreased. The percentage of males was significantly higher in the single-animal accidents. Annual attrition due to vehicle collisions averaged 0.8 percent of the population. Wild pig-vehicle collisions occurred year-round and throughout the 24-hour daily time period. Most accidents were at night. The presence of lateral barriers was significantly more frequent at the collision locations. Human injuries were infrequent but potentially serious. The mean vehicle damage estimate was $1,173.

  19. Uranus' Unstable Moons: Collision Outcomes and Implications

    NASA Astrophysics Data System (ADS)

    Cave, Rosemary; Agnor, Craig B.

    2017-06-01

    Orbital integrations of the Uranian satellite system demonstrate that the closest groups of satellites (Cressida-Desdemona and Cupid-Belinda-Perdita) will evolve to crossing orbits on timescales of 103 - 107 years (Duncan and Lissauer 1997, French and Showalter 2012). Thus, collisions between neighbouring Uranian satellites appear to be an inevitable aspect of the system's evolution.For low-velocity collisions in free space, simple mergers are a plausible outcome. However, when impacts occur near a primary's Roche zone, strong tidal forces complicate the outcomes. Previous analytic work, examining collisions of two solid spheres in a strong tidal field, demonstrates that accretion may be constrained by the mass ratio and bulk density of the impacting bodies (Ohtsuki 1993, Canup and Esposito 1995). Further, direct modelling of collisions between gravitational aggregates near Saturn's F-ring shows complex non-merging outcomes (Karjalainen 2007, Hyodo and Ohtsuki 2014).We are examining the outcomes of collisions between Uranus' unstable satellites. We are using the Rebound N-body code to conduct direct simulations of collisions in the tidal field of Uranus, treating satellites as gravitationally bound rubble piles. These models include a range of satellite densities, impact velocities and orientations appropriate to the most unstable satellites. At the meeting we shall present our model results, and discuss how collision outcomes constrain the bulk composition and interior structure of these satellites, and how these outcomes may inform the past and future evolution of the system.

  20. Radii broadening due to molecular collision in focused ion beams

    NASA Astrophysics Data System (ADS)

    Komuro, Masanori

    1988-01-01

    Point exposures of poly(methyl methacrylate) resist are carried out with focused ion beams of Si++ and Au++ from a liquid AuSi ion source in order to obtain a current density distribution in the probe. All the distributions are composed of a main Gaussian distribution and a long tail dependent on r-3.3 (r means radial distance). The magnitude of this tail increases with the increase in ambient pressure of the ion-drifting space. When the probe is steered at the corner of deflection field, two types of clear ghost patterns appear: (1) circular patterns and (2) lines trailing from the main spot toward the deflection center. It is revealed that they are produced by exposures to ions or energetic neutrals generated with charge transfer collision of the primary ions with residual gas molecules. It is shown that the long tail in the current density distribution is also due to scattering with the residual gas molecules.

  1. Antiproton production in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Jacak, B. V.

    In high energy p-p and alpha-alpha collisions, baryons are observed predominantly at rapidities near those of target and projectile; the mean rapidity shift of projectile and target nucleons is approximately one unit. In the central rapidity region, the number of baryons is quite small. In fact, the number of baryons and antibaryons is rather similar, indicating that most of these baryons are CREATED particles rather than projectile and target fragments. Antibaryon production is of interest in heavy ion collisions as enhanced antiquark production has been predicted as a potential signature of quark-gluon plasma formation. Antibaryons also provide a sensitive probe of the hadronic environment, via annihilation and/or mean field effects upon their final distributions. However, the collision dynamics also affect the baryon and antibaryon distributions. Baryons are more shifted toward midrapidity in nucleus-nucleus and p-p nucleus collisions than in p-p collisions, increasing the probability of annihilating the antibaryons. The interpretation of antibaryon yields is further complicated by collective processes which may take place in the dense hadronic medium formed in nucleus-nucleus collisions. Jahns and coworkers have shown that multistep processes can increase antibaryon production near threshold. Antiproton production is clearly very interesting, but is sensitive to a combination of processes taking place in the collision. The final number of observed antiprotons depends on the balance between mechanisms for extra antiproton production beyond those from the individual nucleon-nucleon collisions and annihilation with surrounding baryons. We can hope to sort out these things by systematic studies, varying the system size and beam energy. I will review what is known about antiproton production at both the AGS and SPS, and look at trends going from p-p to p-nucleus to nucleus-nucleus collisions.

  2. Vorticity in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Deng, Wei-Tian; Huang, Xu-Guang

    2016-06-01

    We study the event-by-event generation of flow vorticity in the BNL Relativistic Heavy Ion Collider Au +Au collisions and CERN Large Hadron Collider Pb +Pb collisions by using the hijing model. Different definitions of the vorticity field and velocity field are considered. A variety of properties of the vorticity are explored, including the impact parameter dependence, the collision energy dependence, the spatial distribution, the event-by-event fluctuation of the magnitude and azimuthal direction, and the time evolution. In addition, the spatial distribution of the flow helicity is also studied.

  3. Holographic heavy ion collisions with baryon charge

    SciTech Connect

    Casalderrey-Solana, Jorge; Mateos, David; van der Schee, Wilke; Triana, Miquel

    2016-09-19

    We numerically simulate collisions of charged shockwaves in Einstein-Maxwell theory in anti-de Sitter space as a toy model of heavy ion collisions with non-zero baryon charge. The stress tensor and the baryon current become well described by charged hydrodynamics at roughly the same time. The effect of the charge density on generic observables is typically no larger than 15%. Finally, we find significant stopping of the baryon charge and compare our results with those in heavy ion collision experiments.

  4. Reactive collisions of atoms with diatomic molecules

    NASA Astrophysics Data System (ADS)

    Wolniewicz, L.; Hinze, Juergen; Alijah, Alexander

    1993-08-01

    The theory of the reactive collision of an atom with a diatomic molecule is formulated in 'democratic' hyperspherical coordinates. An adiabatic ansatz is used to separate the distance coordinate from the angular coordinates. The angular eigenvalue problem is solved, using the hyperspherical harmonics as basis functions, while the R-matrix propagation method is used to integrate the resulting coupled equations along the distance coordinate. As an example, reactive collision probabilities for H + H2 are computed, using the Porter-Karplus surface. The symmetry requirements, when dealing with three identical Fermions in the collision, are considered explicitly.

  5. Antioscillons from bubble collisions at finite temperature

    NASA Astrophysics Data System (ADS)

    Mersini-Houghton, Laura

    2014-04-01

    We study the role of the topology of bubbles at finite temperatures plays on collisions and the existence of new field configurations. We show that in the case of false vacuum decay at finite temperature, the cylindrical symmetry of bubbles admits a new exotic field with negative energies, the antiperiodic "twisted" field. New field configurations arise generically, not only at finite temperatures but whenever a cluster of bubbles resulting from collisions form nontrivial topologies. The interaction of both configurations induces instabilites on the bubble. Collisions of bubbles occupied by the new fields can lead to the emergence of new structures, named antioscillons.

  6. Collisions between quasi-parallel shocks

    NASA Technical Reports Server (NTRS)

    Cargill, Peter J.

    1991-01-01

    The collision between pairs of quasi-parallel shocks is examined using hybrid numerical simulations. In the interaction, the two shocks are transmitted through each other leaving behind a hot plasma with a population of particles with energies in excess of 40 E0, where E0 is the kinetic energy of particles in the shock frame prior to the collision. The energization is more efficient for quasi-parallel shocks than parallel shocks. Collisions between shocks of equal strengths are more efficient than those that are unequal. The results are of importance for phenomena during the impulsive phase of solar flares, in the distant solar wind and at planetary bow shocks.

  7. Low Energy Inelastic Atomic and Molecular Collisions.

    DTIC Science & Technology

    1981-04-15

    oemey A 17 mca mem ewa) atomic collisions deuterium molecular Collisions hydrogen argon .. excitation C argon Ions Ion beams LU & AinVIACt~ re- o sed a...1981). The intent of this work., described in our proposal, was toI obtain sufficient resolution of phosphorus, sulfur and argon L-x rays under single...collision, there are other intense VUV lines as well: the dominant ones observed in the 500-1100 A range were emission from the 2p excitation of neutral He

  8. A collision avoidance system for workpiece protection

    SciTech Connect

    Schmitt, D.J.; Weber, T.M.; Novak, J.L.; Maslakowski, J.E.

    1995-04-01

    This paper describes an application of Sandia`s non-contact capacitive sensing technology for collision avoidance during the manufacturing of rocket engine thrust chambers. The collision avoidance system consists of an octagon shaped collar with a capacitive proximity sensor mounted on each face. The sensors produced electric fields which extend several inches from the face of the collar and detect potential collisions between the robot and the workpiece. A signal conditioning system processes the sensor output and provides varying voltage signals to the robot controller for stopping the robot.

  9. Injuries in Near-Side Collisions

    PubMed Central

    Augenstein, J.; Perdeck, E.; Bowen, J.; Stratton, J.; Singer, M.; Horton, T.; Rao, A.; Digges, K.; Malliaris, A.; Steps, J.

    1999-01-01

    This paper examines crash characteristics and the resulting injuries to occupants whose seat position is on the side of impact in a vehicle exposed to a side collision. The databases of the 1988–96 NASS/CDS and the 1995–98 William Lehman Injury Research Center (WLIRC) are examined in this study. The subset of cases analyzed is those in which there is a vehicle-to-vehicle near-side collision, occupant compartment damage and no subsequent collision or rollover. The WLIRC data contains highly detailed occupant injury data not available in NASS.

  10. Holographic heavy ion collisions with baryon charge

    NASA Astrophysics Data System (ADS)

    Casalderrey-Solana, Jorge; Mateos, David; van der Schee, Wilke; Triana, Miquel

    2016-09-01

    We numerically simulate collisions of charged shockwaves in Einstein-Maxwell theory in anti-de Sitter space as a toy model of heavy ion collisions with non-zero baryon charge. The stress tensor and the baryon current become well described by charged hydrodynamics at roughly the same time. The effect of the charge density on generic observables is typically no larger than 15%. We find significant stopping of the baryon charge and compare our results with those in heavy ion collision experiments.

  11. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  12. Liquid electrolytes

    SciTech Connect

    Nagai, J.; Mizuhashi, M.; Kamimori, T.

    1990-12-31

    In contrast to lithium batteries, the electrochromic windows are used under the sunlight, which requires the stability against UV-light, in addition to the usual electrochemical and thermal stabilities. Thus, the selection of the electrode materials and the combination with the electrolytes should be carefully performed in terms of stability requirements. Recently many reports in relation to those subjects were published. Therefore only fundamental properties of liquid electrolytes required for the electrochromic research are reviewed in this chapter.

  13. Collision experiments between centimeter-sized protoplanetesimals in microgravity

    NASA Astrophysics Data System (ADS)

    Whizin, Akbar; Colwell, Joshua E.; Dove, Adrienne; Brisset, Julie; Cruz, Roberto; Foster, Zach

    2016-10-01

    In the early stages of planet formation in a protoplanetary disk the first coalescing bodies are weakly bound. Conditions in the disk, such as the presence of gas (drag), make further growth through centimeter and meter sized bodies difficult. For centimeter-sized aggregates self-gravity is almost non-existent and electrostatic surface forces such as van der Waals-type forces play a critical role in holding loosely bound rubble-piles together during their early formation. In order to understand how aggregates of this size grow we study the mechanical strengths, material, and collisional properties of cm-sized aggregates. The collisional outcomes between two aggregates can be determined by a set of definable collision parameters and experimental constraints on these parameters will aid in astrophysical models of planet formation. We have carried out a series of microgravity laboratory experiments in which we collide a pair of weakly bound aggregates together. In our free-fall chamber we collide two 3-cm aggregates together at collision velocities ranging from 50 to 220 cm/s and with pressure ~1 mbar. The aggregates are made of mm-sized silica bead particles and require internal cohesion to avoid fragmentation above modest collision speeds, which is supplied by adding H2O (later dehydrated) and between 0 - 0.1 g of a well-mixed liquid adhesive to simulate surface forces and bonds between particles. We measure the compressive strengths of the aggregates (0.5 - 10 kPa), find their coefficients of restitution (CoR), and determine their bouncing and fragmentation thresholds, over a range of velocities and internal strengths. We observed collisional outcomes such as bouncing, erosion (mass-loss), and fragmentation of the aggregates. We find the CoR of the aggregates to have a mean of 0.11 ± 0.1 with no dependence on velocity or strength. Impact velocities above ~2 m/s resulted in fragmentation of our aggregates, higher than the ~1 m/s threshold for porous dust aggregates

  14. Mean field and collisions in hot nuclei

    SciTech Connect

    K /umlt o/hler, H.S.

    1989-06-01

    Collisions between heavy nuclei produce nuclear matter of high density and excitation. Brueckner methods are used to calculate the momentum and temperature dependent mean field for nucleons propagating through nuclear matter during these collisions. The mean field is complex and the imaginary part is related to the ''two-body'' collision, while the real part relates to ''one-body'' collisions. A potential model for the N-N interactions is avoided by calculating the Reaction matrix directly from the T-matrix (i.e., N-N phase shifts) using a version of Brueckner theory previously published by the author. Results are presented for nuclear matter at normal and twice normal density and for temperatures up to 50 MeV. 23 refs., 7 figs.

  15. Efficient DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-05-01

    The effect of collision-partner selection schemes on the accuracy and the efficiency of the Direct Simulation Monte Carlo (DSMC) method of Bird is investigated. Several schemes to reduce the total discretization error as a function of the mean collision separation and the mean collision time are examined. These include the historically first sub-cell scheme, the more recent nearest-neighbor scheme, and various near-neighbor schemes, which are evaluated for their effect on the thermal conductivity for Fourier flow. Their convergence characteristics as a function of spatial and temporal discretization and the number of simulators per cell are compared to the convergence characteristics of the sophisticated and standard DSMC algorithms. Improved performance is obtained if the population from which possible collision partners are selected is an appropriate fraction of the population of the cell.

  16. Efficient DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-07-01

    The effect of collision-partner selection schemes on the accuracy and the efficiency of the Direct Simulation Monte Carlo (DSMC) method of Bird is investigated. Several schemes to reduce the total discretization error as a function of the mean collision separation and the mean collision time are examined. These include the historically first sub-cell scheme, the more recent nearest-neighbor scheme, and various near-neighbor schemes, which are evaluated for their effect on the thermal conductivity for Fourier flow. Their convergence characteristics as a function of spatial and temporal discretization and the number of simulators per cell are compared to the convergence characteristics of the sophisticated and standard DSMC algorithms. Improved performance is obtained if the population from which possible collision partners are selected is an appropriate fraction of the population of the cell.

  17. Resonance formation in photon-photon collisions

    SciTech Connect

    Gidal, G.

    1988-08-01

    Recent experimental progress on resonance formation in photon-photon collisions is reviewed with particular emphasis on the pseudoscalar and tensor nonents and on the ..gamma gamma..* production of spin-one resonances. 37 refs., 17 figs., 5 tabs.

  18. Traffic collision during the breakup of an aqueous viscous compound jet

    NASA Astrophysics Data System (ADS)

    Doméjean, Hugo; Bibette, Jérôme; Bremond, Nicolas

    2016-10-01

    Liquid jets ultimately break up into droplets through an instability driven by surface tension. For highly viscous liquids, drops are connected by cylindrical liquid filaments whose radii linearly decrease with time, thus forming drops on a string structure. For a jet composed of two aqueous phases made in air by coaxial extrusion, we observe that, for moderate Weber and capillary numbers, drops slow down with different velocities, leading to drop coalescence. The origin of the traffic collision is linked to the spatial feature of the capillary instability where capillary and viscous forces acting on the drops evolve along the jet and ultimately amplify small velocity fluctuations. The emergence of such fluctuations is related to the unstable nature of the annular coflow of liquids having contrasting viscoelastic properties. From a practical point of view, flow and actuation conditions can be adjusted to inhibit drop collision and thus drop coalescence. These findings allow then the fabrication of monodisperse submillimeter core-shell objects based on the fragmentation of compound jets made of polymer solutions that find applications for three-dimensional cell culture.

  19. Central collisions-The general case

    NASA Astrophysics Data System (ADS)

    Lyublinskaya, Irina E.

    1998-01-01

    The central elastic and inelastic collisions have been analyzed in general vector form. The proposed analysis results in equations, which have simple physical interpretation and can be easily applied to different special cases. The mathematical basis needed for the analysis includes only vector addition and dot-product of vectors. It allows teachers to introduce proposed approach to collisions already in trigonometry-based physic courses.

  20. Atomic and Molecular Depolarizing Collision Rates

    NASA Astrophysics Data System (ADS)

    Bommier, V.

    2009-06-01

    This paper is divided in three parts: after having recalled the different types of collisions with the different types of perturbers and having provided rough orders of magnitude of the collision rates, three cases are discussed. Although the most frequent type of depolarizing collision is the one of the collisions with the surrounding Hydrogen atoms, we discuss in the first part a particular case where the depolarizing collision effect is due to collisions with electrons and protons. This is the case of the Hydrogen lines observed in solar prominences. We recall how the interpretation of polarization observations in two lines has led to the joint determination of the magnetic field vector and the electron and proton density, and we show that this density determination gives results in agreement with the densities determined by interpretation of the Stark effect, provided that this last effect be evaluated in the impact approximation scheme which is indeed more valid than the quasistatic approach at these densities. In the second part, we describe a method that has been recently developed for the computation of the depolarizing rates in the case of collisions with the neutral Hydrogen atom. The case of molecular lines is less favourable, because, even if depolarizing collision rates computation may be soon expected and begin to be done inside the ground level of the molecule, calculations inside the excited states are far from the present ability. In the third part, we present an example where the excited state depolarizing rates were evaluated together with the magnetic field through the differential Hanle effect interpretation, based on the fact that the molecule provides a series of lines of different sensitivities that can be compared. This led to an experimental/observational determination of these rates, waiting for future theoretical computations for comparison.

  1. Molecular vibrational states during a collision

    NASA Technical Reports Server (NTRS)

    Recamier, Jose A.; Jauregui, Rocio

    1995-01-01

    Alternative algebraic techniques to approximate a given Hamiltonian by a harmonic oscillator are described both for time-independent and time-dependent systems. We apply them to the description of a one dimensional atom-diatom collision. From the resulting evolution operator, we evaluate vibrational transition probabilities as well as other time-dependent properties. As expected, the ground vibrational state becomes a squeezed state during the collision.

  2. Collision avoidance in computer optimized treatment planning.

    PubMed

    Humm, J L

    1994-07-01

    Of major concern in fully automated computerized treatment delivery is the possibility of gantry/couch or gantry/patient collisions. In this work, software has been developed to detect collisions between gantry and couch or patient for both transaxial and noncoplanar treatment fields during the treatment planning process. The code uses the gantry angles, turntable angles, and position of the couch surface relative to the isocenter supplied by the planner for the prescribed radiation fields. In addition, the maximum patient anterior-posterior and lateral separations are entered in order to model the patient outline by a conservative cylindrical ellipse. By accessing a database containing the precise mechanical dimensions of the therapy equipment, 3D analytical geometry is used to test for collisions between gantry/patient and gantry/couch for each treatment field. When collisions are detected, the software inspects the use of an extended distance treatment, by recalculating and testing for collisions, with the couch at a greater distance from the collimator along the direction of the central axis. If a collision is avoided at extended distance, the lateral, longitudinal, and vertical motions of the couch are recorded for entry into the treatment plan, or else a warning message is printed, together with the nearest permissible collision-free gantry angle. Upon inspection, the planner can either elect to use the calculated closest permissible gantry angle or reject the plan. The software verifies that each proposed treatment field is safe, but also that the transition between fields is collision-free. This requires that the sequence of the treatment fields be ordered, preferably into a sequence which minimizes the delivery time compatible with patient safety.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Low Noise Fractional NTC Collisions for DSMC

    DTIC Science & Technology

    2012-05-01

    post-collision number of macro particles. Figure 3 shows the effect of varying the number of particles on the RMS error. The variance in temperature...Consideration of effective -Coulomb collisions is considered later. Figure 4 shows that the variable soft sphere (VSS) thermalization of the oscillating beams...particles in every timestep, the merging algorithm effectively maintains the target number of computational particles preventing runaway growth. Figure 5

  4. Collision integrals for isotopic hydrogen molecules.

    NASA Technical Reports Server (NTRS)

    Brown, N. J.; Munn, R. J.

    1972-01-01

    The study was undertaken to determine the effects of reduced mass and differences in asymmetry on the collision integrals and thermal diffusion factors of isotopic hydrogen systems. Each system selected for study consisted of two diatoms, one in the j = 0 rotation state and the other in the j = 1 state. The molecules interacted with a Lennard-Jones type potential modified to include angular terms. A set of cross sections and collision integrals were obtained for each system.

  5. Coulomb collision effects on linear Landau damping

    SciTech Connect

    Callen, J. D.

    2014-05-15

    Coulomb collisions at rate ν produce slightly probabilistic rather than fully deterministic charged particle trajectories in weakly collisional plasmas. Their diffusive velocity scattering effects on the response to a wave yield an effective collision rate ν{sub eff} ≫ ν and a narrow dissipative boundary layer for particles with velocities near the wave phase velocity. These dissipative effects produce temporal irreversibility for times t ≳ 1/ν{sub eff} during Landau damping of a small amplitude Langmuir wave.

  6. Jets in relativistic heavy ion collisions

    SciTech Connect

    Wang, Xin-Nian; Gyulassy, M.

    1990-09-01

    Several aspects of hard and semihard QCD jets in relativistic heavy ion collisions are discussed, including multiproduction of minijets and the interaction of a jet with dense nuclear matter. The reduction of jet quenching effect in deconfined phase of nuclear matter is speculated to provide a signature of the formation of quark gluon plasma. HIJING Monte Carlo program which can simulate events of jets production and quenching in heavy ion collisions is briefly described. 35 refs., 13 figs.

  7. Nuclear collisions at the Future Circular Collider

    NASA Astrophysics Data System (ADS)

    Armesto, N.; Dainese, A.; d'Enterria, D.; Masciocchi, S.; Roland, C.; Salgado, C. A.; van Leeuwen, M.; Wiedemann, U. A.

    2016-12-01

    The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.

  8. Collision integrals for isotopic hydrogen molecules.

    NASA Technical Reports Server (NTRS)

    Brown, N. J.; Munn, R. J.

    1972-01-01

    The study was undertaken to determine the effects of reduced mass and differences in asymmetry on the collision integrals and thermal diffusion factors of isotopic hydrogen systems. Each system selected for study consisted of two diatoms, one in the j = 0 rotation state and the other in the j = 1 state. The molecules interacted with a Lennard-Jones type potential modified to include angular terms. A set of cross sections and collision integrals were obtained for each system.

  9. Collisions with passenger cars and moose, Sweden.

    PubMed Central

    Björnstig, U; Eriksson, A; Thorson, J; Bylund, P O

    1986-01-01

    The number of collisions between motor vehicles and moose is increasing in many countries. Collisions with large, high animals such as moose cause typical rear- and downward deformation of the windshield pillars and front roof, most pronounced for small passenger cars; the injury risk increases with the deformation of the car. A strengthening of the windshield pillars and front roof and the use of antilacerative windshields would reduce the injury risk to car occupants. PMID:3953927

  10. Theoretical Studies of Rydberg Atom Collisions.

    DTIC Science & Technology

    1984-11-28

    capture cross section shoved considerable enhancement if the Rydberg electron was oriented in a plane parallel to the direction of the incident...Astronomy Rice Univesity Theoretical approaches to low-energy collisions of Rydberg atoms with atoms and Ions A. P. HICKMAN, R. E. OLSON, AND J. PASCALE... parallel to the direction of the incident projectile. Laser-assisted charge-transfer collisions: K~ + Na T. P. an. K. Kimura ad 1. E. Olson Dept. of

  11. Icy Collisions - Planet Building beyond the snowline

    NASA Astrophysics Data System (ADS)

    Gaertner, Sabrina; Hill, Catherine; Heisselmann, Daniel; Blum, Juergen; Fraser, Helen

    2015-11-01

    Collisions of small icy and dust particles beyond the “snow-line” are a key step in planet formation. Whilst the physical forces that underpin the aggregation of the smallest grains (van der Waals) and the largest planetessimals (gravity) are well understood, the processes involving mm - cm sized particles remain a mystery.In a unique set of experiments, we investigated low velocity collisions of dust and icy particles in this size range under microgravity conditions - utilizing parabolic flight (e.g. Salter 2009, Hill 2015 (a) & (b)). Experiments were performed at cryogenic temperatures (below 140 K) for icy aggregates and ambient as well as cryogenic temperatures (80 - 220 K) for dust aggregates.The kinetic analysis of the observed collisions of different aggregate types in different shapes and sizes revealed astonishing results - as the collisional properties of all investigated particles differ strongly from the usual assumptions in models of planet formation.Here, we present a summary of the results on the collisions of icy particles as well as first results on the collisions of dust aggregates. Focus will be on the coefficient of restitution, which measures the loss of translational energy in bouncing collisions and is a key parameter in models of planet formation.

  12. Planetesimal Collisions as a Chondrule Forming Event

    NASA Astrophysics Data System (ADS)

    Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi; Hasegawa, Yasuhiro

    2017-01-01

    Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of the chondrule forming processes—planetesimal collisions. Previous studies have found that impact jetting via protoplanet–planetesimal collisions can make chondrules with 1% of the impactors’ mass, when the impact velocity exceeds 2.5 km s‑1. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal–planetesimal collisions using a shock physics code and find two things: one is that planetesimal–planetesimal collisions produce nearly the same amount of chondrules as protoplanet–planetesimal collisions (∼1%). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find that progenitors of chondrules can originate from deeper regions of large targets (planetesimals or protoplanets) than small impactors (planetesimals). The composition of targets is therefore important, to fully account for the mineralogical data of currently sampled chondrules.

  13. The Underlying Physics in Wetted Particle Collisions

    NASA Astrophysics Data System (ADS)

    Donahue, Carly; Hrenya, Christine; Davis, Robert

    2008-11-01

    Wetted granular particles are relevant in many industries including the pharmaceutical and chemical industries and has applications to granulation, filtration, coagulation, spray coating, drying and pneumatic transport. In our current focus, we investigate the dynamics of a three-body normal wetted particle collision. In order to conduct collisions we use an apparatus called a ``Stokes Cradle,'' similar to the Newton's Cradle (desktop toy) except that the target particles are covered with oil. Here, we are able to vary the oil thickness, oil viscosity, and material properties. With a three particle collision there are four possible outcomes: fully agglomerated (FA); Newton's Cradle (NC), the striker and the first target ball are agglomerated and the last target ball is separated; Reverse Newton's Cradle (RNC), the striker is separated and the two targets are agglomerated; and fully separated (FS). Varying the properties of the collisions, we have observed all four outcomes. We use elastohydrodynamics as a theoretical basis for modeling the system. We also have considered the glass transition of the oil as the pressure increases upon impact and the cavitation of the oil as the pressure drops below the vapor pressure upon rebound. A toy model has been developed where the collision is modeled as a series of two-body collisions. A qualitative agreement between the toy model and experiments gives insight into the underlying physics.

  14. Current transients in single nanoparticle collision events.

    PubMed

    Xiao, Xiaoyin; Fan, Fu-Ren F; Zhou, Jiping; Bard, Allen J

    2008-12-10

    Electrochemical hydrazine oxidation and proton reduction occur at a significantly higher rate at Pt than at Au or C electrodes. Thus, the collision and adhesion of a Pt particle on a less active Au or C electrode leads to a large current amplification by electrocatalysis at single nanoparticles (NPs). At low particle concentrations, the collision of Pt NPs was characterized by current transients composed of individual current profiles that rapidly attained a steady state, signaling single NP collisions. The characteristic steady-state current was used to estimate the particle size. The fluctuation in collision frequency with time indicates that the collision of NPs at the detector electrodes occurs in a statistically random manner, with the average frequency a function of particle concentration and diffusion coefficient. A longer term current decay in single current transients, as opposed to the expected steady-state behavior, was more pronounced for proton reduction than for hydrazine oxidation, revealing microscopic details of the nature of the particle interaction with the detector electrode and the kinetics of electrocatalysis at single NPs. The study of single NP collisions allows one to screen particle size distributions and estimate NP concentrations and diffusion coefficients.

  15. Collision induced migration of adsorbates on surfaces

    NASA Astrophysics Data System (ADS)

    Romm, L.; Asscher, M.; Zeiri, Y.

    1999-06-01

    Collision induced migration (CIM) has been identified as a new surface phenomenon and has been studied for the first time using molecular dynamics simulations. The CIM process was represented by an energetic gas phase argon atom, striking an adsorbed nitrogen molecule on Ru(001). The efficiency of CIM was investigated as a function of the collider initial kinetic energy and angle of incidence. It was found that at low coverages an adsorbed molecule can migrate more than 150 Å following collisions at high energies and grazing angles of incidence. As coverage increases, inter-adsorbate collisions result in significant reduction of migration distances. At high energies, the competing process of collision induced desorption becomes dominant, leaving behind molecules which migrate shorter distances. These competing channels lead to a collision energy for which CIM is maximized. For the N2/Ru system, the CIM process is most effective near collider energy of 2.0 eV. This new surface phenomenon of CIM has to be considered for better understanding the full range of surface processes which govern industrial high pressure catalysis. At the tail of the thermal kinetic energy distribution, energetic colliders from the gas phase lead to CIM and generate high energy inter-adsorbate collisions, sometimes discussed in terms of "hot-particle" chemistry.

  16. Estimating collision efficiencies from contact freezing experiments

    NASA Astrophysics Data System (ADS)

    Nagare, B.; Marcolli, C.; Stetzer, O.; Lohmann, U.

    2015-04-01

    Interactions of atmospheric aerosols with clouds influence cloud properties and modify the aerosol life cycle. Aerosol particles act as cloud condensation nuclei and ice nucleating particles or become incorporated into cloud droplets by scavenging. For an accurate description of aerosol scavenging and ice nucleation in contact mode, collision efficiency between droplets and aerosol particles needs to be known. This study derives the collision rate from experimental contact freezing data obtained with the ETH Collision Ice Nucleation Chamber CLINCH. Freely falling 80 μm water droplets are exposed to an aerosol consisting of 200 nm diameter silver iodide particles of concentrations from 500-5000 cm-3, which act as ice nucleating particles in contact mode. The chamber is kept at ice saturation in the temperature range from 236-261 K leading to slow evaporation of water droplets giving rise to thermophoresis and diffusiophoresis. Droplets and particles bear charges inducing electrophoresis. The experimentally derived collision efficiency of 0.13 is around one order of magnitude higher than theoretical formulations which include Brownian diffusion, impaction, interception, thermophoretic, diffusiophoretic and electric forces. This discrepancy is most probably due to uncertainties and inaccuracies in the description of thermophoretic and diffusiophoretic processes acting together. This is to the authors knowledge the first dataset of collision efficiencies acquired below 273 K. More such experiments with different droplet and particle diameters are needed to improve our understanding of collision processes acting together.

  17. Liquid air mixing system

    NASA Technical Reports Server (NTRS)

    Martin, Robert B. (Inventor)

    1997-01-01

    A device for mixing liquid nitrogen and liquid oxygen to form liquid air. The mixing device consists of a tube for transferring liquid oxygen positioned within a tube for transferring liquid nitrogen. Supply vessels for liquid oxygen and liquid nitrogen are equally pressurized and connected to the appropriate tubes. Liquid oxygen and nitrogen flow from the supply vessels through the respective tubes and are mixed to form liquid air upon exiting the outlets of the tube. The resulting liquid air is transferred to a holding vessel.

  18. Gas-Microjet Reactive Scattering: Collisions of HCl and DCl with Cool Salty Water.

    PubMed

    Faust, Jennifer A; Sobyra, Thomas B; Nathanson, Gilbert M

    2016-02-18

    Liquid microjets provide a powerful means to investigate reactions of gases with salty water in vacuum while minimizing gas-vapor collisions. We use this technique to explore the fate of gaseous HCl and DCl molecules impinging on 8 molal LiCl and LiBr solutions at 238 K. The experiments reveal that HCl or DCl evaporate infrequently if they become thermally accommodated at the surface of either solution. In particular, we observe minimal thermal desorption of HCl following HCl collisions and no distinct evidence for rapid, interfacial DCl→HCl exchange following DCl collisions. These results imply that surface thermal motions are not generally strong enough to propel momentarily trapped HCl or DCl back into the gas phase before they ionize and disappear into solution. Instead, only HCl and DCl molecules that scatter directly from the surface escape entry. These recoiling molecules transfer less energy upon collision to LiBr/H2O than to LiCl/H2O, reflecting the heavier mass of Br(-) than of Cl(-) in the interfacial region.

  19. Time ordering in atomic collisions

    NASA Astrophysics Data System (ADS)

    McGuire, J. H.; Godunov, A. L.; Shakov, Kh Kh; Kaplan, L.; Burin, A.; Uskov, D.

    2007-06-01

    Time ordering constrains interactions to occur in increasing (or decreasing) order. This places a constraint on the time evolution of the system and can lead to correlations in time of different particles in a few/many body system. Unlike overall time reversal, time ordering is not a conserved symmetry of the atomic system. A number of examples of observable effects of time ordering are presented. A convenient way to describe time ordering is to define the limit of no time ordering by replacing the instantaneous interaction by its time average. This is similar to the way in which spatial correlation is defined. Like spatial correlation, time ordering is usually formulated in the interaction representation. The effects of time ordering can differ in different representations. In energy space, conjugate to time space, time ordering is imposed as the i ɛ term in the Greens' function that corresponds to an initial condition (usually incoming plane waves and outgoing scattered waves). This permits off-energy-shell (energy non- conserving) fluctuations during the collision consistent with the Uncertainty Principle.

  20. Impulsive model for reactive collisions

    NASA Technical Reports Server (NTRS)

    Marron, M. T.; Bernstein, R. B.

    1972-01-01

    A simple classical mechanical model of the reactive scattering of a structureless atom A and a quasi-diatomic BC is developed which takes full advantage of energy, linear and angular momentum conservation relations but introduces a minimum of further assumptions. These are as follows: (1) the vibrational degree of freedom of the reactant (BC) and product (AB) molecules is suppressed, so the change in vibrational energy is simply a parameter; (2) straight-line trajectories are assumed outside of a reaction shell; (3) within this zone, momentum transfer occurs impulsively (essentially instantaneously) following mass transfer; (4) the impulse, which may be either positive or negative, is directed along the BC axis, which may, however, assume all orientations with respect to the incident relative velocity. The model yields differential and total cross sections and product rotational energy distributions for a given collision exoergicity Q, or for any known distribution over Q. Numerical results are presented for several prototype reactions whose dynamics have been well-studied.

  1. GALAXY COLLISIONS IN DISTANT CLUSTER

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The group of galaxies -- or 'galaxy cluster' -- catalogued as MS1054-03 is 8 billion light-years away, one of the most distant known so far. Although hundreds of galaxies appear in the NASA/ESA Hubble Space Telescope image, a European-led team of astronomers has studied in detail 81 galaxies that certainly belong to the cluster, 13 of which are remnants of recent collisions or pairs of colliding galaxies. This is by far the largest number of colliding galaxies ever found in a cluster. The picture is actually a 'mosaic' of images, so that astronomers can have a much wider view of the distant cluster. This is why the colliding galaxies, mostly located in clumps in the outskirts of the cluster, had not been discovered so far. In the image, streams of stars can be seen being pulled out of the galaxies, a consequence of the huge tidal forces in action. The red color of most of the merger remnants means that the stars are old and not much star formation has 'recently' taken place. The observations with the Hubble were made in May 1998. The 10-meter Keck telescope in Hawaii was used to confirm that the colliding galaxies were part of the cluster. Photo Credits: Pieter van Dokkum, Marijn Franx (University of Groningen/Leiden), ESA and NASA

  2. RELATIVISTIC HEAVY ION COLLISIONS: EXPERIMENT

    SciTech Connect

    Friedlander, Erwin M.; Heckman, Harry H.

    1982-04-01

    Relativistic heavy ion physics began as a 'no man's land' between particle and nuclear physics, with both sides frowning upon it as 'unclean', because on one hand, hadronic interactions and particle production cloud nuclear structure effects, while on the other, the baryonic environment complicates the interpretation of production experiments. They have attempted to review here the experimental evidence on RHI collisions from the point of view that it represents a new endeavor in the understanding of strong interaction physics. Such an approach appears increasingly justified; first, by the accumulation of data and observations of new features of hadronic interactions that could not have been detected outside a baryonic environment; second, by the maturation of the field owing to the advances made over the past several years in experimental inquiries on particle production by RHI, including pions, kaons, hyperons, and searches for antiprotons; and third, by the steady and progressive increase in the energy and mass ranges of light nuclear beams that have become available to the experiment; indeed the energy range has widened from the {approx} 0.2 to 2 AGeV at the Bevalac to {approx}4 AGeV at Dubna and recently, to the quantum jump in energies to {approx} 1000 equivalent AGeV at the CERN PS-ISR. Accompanying these expansions in the energy frontier are the immediate prospects for very heavy ion beams at the Bevalac up to, and including, 1 AGeV {sup 238}U, thereby extending the 'mass frontier' to its ultimate extent.

  3. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  4. A zero-gravity demonstration of the collision and coalescence of water droplets

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Vaughan, O. H.; Smith, R. E.

    1974-01-01

    The mechanics of the collision and coalescence of liquid droplets is one of the main research areas in the fields of nuclear physics, astrophysics, meteorology and fluid mechanics. The crew members on the Skylab 3 and 4 missions were requested to perform demonstrations of the collision and coalescence of water droplets under the low gravity environment at orbital altitude. In Skylab 4 two water droplets with equal volumes, 30 cu cm each, were used. A dark colored droplet (contaminated with grape drink) moving with a velocity of 3.14 cm/sec collided with a stationary pink colored droplet (contaminated with strawberry drink) and coalescence occurred. Theoretical models are proposed to study the various stages of the collision-coalescence processes. Special considerations are concentrated in the investigation of the bounce-coalescence and coalescence-instability processes. The surface tension of the coalesced droplets was calculated to be 52 dynes/cm in perfect agreement with laboratory measurements made after the flight using a reproduction of the liquids.

  5. Surfactant effect on interaction of rising bubble and particle in a liquid subjected to vibrations

    NASA Astrophysics Data System (ADS)

    Lyubimov, D. V.; Klimenko, L. S.; Lyubimova, T. P.; Filippov, L. O.

    2017-07-01

    The paper investigates the surfactant effect on the interaction of solid particle and gas bubble in a liquid subjected to vibrations. Surfactant transport between the bubble surface and the surrounding liquid is limited by the adsorption-desorption process. The particle is subjected to the Stokes, Basset and buoyancy forces, and average force related to the inhomogeneity of the pulsational field. The problem is solved numerically. It is found that in the presence of surfactant, the impact of vibrations on the particle-bubble collision is weaker than in the absence of surfactant. Thus, higher vibrations intensity is needed for increasing the collision efficiency, together with a higher consumption in energy.

  6. Extremely-efficient, miniaturized, long-lived alpha-voltaic power source using liquid gallium

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey (Inventor); Patel, Jagdishbhai (Inventor); Fleurial, Jean-Pierre (Inventor)

    2004-01-01

    A power source converts .alpha.-particle energy to electricity for use in electrical systems. Liquid gallium or other liquid medium is subjected to .alpha.-particle emissions. Electrons are freed by collision from neutral gallium atoms to provide gallium ions. The electrons migrate to a cathode while the gallium ions migrate to an anode. A current and/or voltage difference then arises between the cathode and anode because of the work function difference of the cathode and anode. Gallium atoms are regenerated by the receiving of electrons from the anode enabling the generation of additional electrons from additional .alpha.-particle collisions.

  7. Collision prediction software for radiotherapy treatments.

    PubMed

    Padilla, Laura; Pearson, Erik A; Pelizzari, Charles A

    2015-11-01

    This work presents a method of collision predictions for external beam radiotherapy using surface imaging. The present methodology focuses on collision prediction during treatment simulation to evaluate the clearance of a patient's treatment position and allow for its modification if necessary. A Kinect camera (Microsoft, Redmond, WA) is used to scan the patient and immobilization devices in the treatment position at the simulator. The surface is reconstructed using the skanect software (Occipital, Inc., San Francisco, CA). The treatment isocenter is marked using simulated orthogonal lasers projected on the surface scan. The point cloud of this surface is then shifted to isocenter and converted from Cartesian to cylindrical coordinates. A slab models the treatment couch. A cylinder with a radius equal to the normal distance from isocenter to the collimator plate, and a height defined by the collimator diameter is used to estimate collisions. Points within the cylinder clear through a full gantry rotation with the treatment couch at 0°, while points outside of it collide. The angles of collision are reported. This methodology was experimentally verified using a mannequin positioned in an alpha cradle with both arms up. A planning CT scan of the mannequin was performed, two isocenters were marked in pinnacle, and this information was exported to AlignRT (VisionRT, London, UK)--a surface imaging system for patient positioning. This was used to ensure accurate positioning of the mannequin in the treatment room, when available. Collision calculations were performed for the two treatment isocenters and the results compared to the collisions detected the room. The accuracy of the Kinect-Skanect surface was evaluated by comparing it to the external surface of the planning CT scan. Experimental verification results showed that the predicted angles of collision matched those recorded in the room within 0.5°, in most cases (largest deviation -1.2°). The accuracy study for

  8. A numerical investigation of continental collision styles

    NASA Astrophysics Data System (ADS)

    Ghazian, Reza Khabbaz; Buiter, Susanne J. H.

    2013-06-01

    Continental collision after closure of an ocean can lead to different deformation styles: subduction of continental crust and lithosphere, lithospheric thickening, folding of the unsubducted continents, Rayleigh-Taylor (RT) instabilities and/or slab break-off. We use 2-D thermomechanical models of oceanic subduction followed by continental collision to investigate the sensitivity of these collision styles to driving velocity, crustal and lithospheric temperature, continental rheology and the initial density difference between the oceanic lithosphere and the asthenosphere. We find that these parameters influence the collision system, but that driving velocity, rheology and lithospheric (rather than Moho and mantle) temperature can be classified as important controls, whereas reasonable variations in the initial density contrast between oceanic lithosphere and asthenosphere are not necessarily important. Stable continental subduction occurs over a relatively large range of values of driving velocity and lithospheric temperature. Fast and cold systems are more likely to show folding, whereas slow and warm systems can experience RT-type dripping. Our results show that a continent with a strong upper crust can experience subduction of the entire crust and is more likely to fold. Accretion of the upper crust at the trench is feasible when the upper crust has a moderate to weak strength, whereas the entire crust can be scraped-off in the case of a weak lower crust. We also illustrate that weakening of the lithospheric mantle promotes RT-type of dripping in a collision system. We use a dynamic collision model, in which collision is driven by slab pull only, to illustrate that adjacent plates can play an important role in continental collision systems. In dynamic collision models, exhumation of subducted continental material and sediments is triggered by slab retreat and opening of a subduction channel, which allows upward flow of buoyant materials. Exhumation continues

  9. Collision prediction software for radiotherapy treatments

    SciTech Connect

    Padilla, Laura; Pearson, Erik A.; Pelizzari, Charles A.

    2015-11-15

    Purpose: This work presents a method of collision predictions for external beam radiotherapy using surface imaging. The present methodology focuses on collision prediction during treatment simulation to evaluate the clearance of a patient’s treatment position and allow for its modification if necessary. Methods: A Kinect camera (Microsoft, Redmond, WA) is used to scan the patient and immobilization devices in the treatment position at the simulator. The surface is reconstructed using the SKANECT software (Occipital, Inc., San Francisco, CA). The treatment isocenter is marked using simulated orthogonal lasers projected on the surface scan. The point cloud of this surface is then shifted to isocenter and converted from Cartesian to cylindrical coordinates. A slab models the treatment couch. A cylinder with a radius equal to the normal distance from isocenter to the collimator plate, and a height defined by the collimator diameter is used to estimate collisions. Points within the cylinder clear through a full gantry rotation with the treatment couch at 0° , while points outside of it collide. The angles of collision are reported. This methodology was experimentally verified using a mannequin positioned in an alpha cradle with both arms up. A planning CT scan of the mannequin was performed, two isocenters were marked in PINNACLE, and this information was exported to AlignRT (VisionRT, London, UK)—a surface imaging system for patient positioning. This was used to ensure accurate positioning of the mannequin in the treatment room, when available. Collision calculations were performed for the two treatment isocenters and the results compared to the collisions detected the room. The accuracy of the Kinect-Skanect surface was evaluated by comparing it to the external surface of the planning CT scan. Results: Experimental verification results showed that the predicted angles of collision matched those recorded in the room within 0.5°, in most cases (largest deviation

  10. Stimulated Heterogeneous Nucleation of Supercooled Liquid H2 Droplets

    NASA Astrophysics Data System (ADS)

    Knuth, E. L.; Schaper, S.; Toennies, J. P.

    2000-07-01

    The properties of H(2) droplets formed by condensation in a supersonic freejet were probed by the capture and coagulation of CO molecules for the purpose of determining whether the droplets are liquid or solid. The CO was introduced into the H(2) droplets by passing the droplet beam through a scattering chamber containing CO at room temperature and various pressures. Reduction of droplet size as a result of droplet collisions with CO molecules was determined by measuring the droplet size downstream from the scattering region for several different values of the CO pressure. The size of the embedded clusters formed by coagulation of the captured CO molecules was determined from the mass spectra measured for several values of CO pressure in the scattering chamber. A comparison of (a) the observed dramatic loss of about 7% of the H(2) molecules from a droplet after between 2 and 8 collisions with (b) the loss predicted due to evaporation/sublimation in the event of solidification is taken to be compelling evidence that the H(2) droplets were liquid prior to their collisions with the CO scattering gas. The observed dependence of the maximum CO cluster size on the collision frequency appears to indicate that a sufficiently high collision frequency will liquify a droplet which otherwise would be solid. This observation supports the conclusion that the H(2) droplets are solidified as a consequence of heterogeneous nucleation induced by the captured CO molecules. The evidence in favor of a liquid state. coupled with the estimated 4K droplet temperature, suggest strongly that the supercooled H(2) droplets are superfluid.

  11. Stimulated heterogeneous nucleation of supercooled liquid H2 droplets

    NASA Astrophysics Data System (ADS)

    Knuth, E. L.; Schaper, S.; Toennies, J. P.

    2001-08-01

    The properties of H2 droplets formed by condensation in a supersonic freejet were probed by the capture and coagulation of CO molecules for the purpose of determining whether the droplets are liquid or solid. The CO was introduced into the H2 droplets by passing the droplet beam through a scattering chamber containing CO at room temperature and various pressures. Reduction of droplet size as a result of droplet collisions with CO molecules was determined by measuring the droplet size downstream from the scattering region for several different values of the CO pressure. The size of the embedded clusters formed by coagulation of the captured CO molecules was determined from the mass spectra measured for several values of CO pressure in the scattering chamber. A comparison of (a) the observed dramatic loss of about 7% of the H2 molecules from a droplet after between 2 and 8 collisions with (b) the loss predicted due to evaporation/sublimation in the event of solidification is taken to be compelling evidence that the H2 droplets were liquid prior to their collisions with the CO scattering gas. The observed dependence of the maximum CO cluster size on the collision frequency appears to indicate that a sufficiently high collision frequency will liquify a droplet which otherwise would be solid. This observation supports the conclusion that the H2 droplets are solidified as a consequence of heterogeneous nucleation induced by the captured CO molecules. The evidence in favor of a liquid state, coupled with the estimated 4K droplet temperature, suggest strongly that the supercooled H2 droplets are superfluid.

  12. A new method for determining hydrodynamic effects on the collision of two spheres

    SciTech Connect

    Gelbard, F.; Mondy, L.A.; Ohrt, S. )

    1991-03-01

    A sphere falling in a fluid may collide with another sphere falling more slowly if, when the spheres are far apart vertically, the horizontal distance between their centers is less than or equal to a critical radius. Accurate prediction of aerosol particle coagulation requires a good understanding of this process. Previously reported optical techniques for measuring hydrodynamic effects on this phenomenon have inherent difficulties detecting grazing collisions and hence in determining the critical radius. In this work, a novel detection technique is demonstrated and it is shown that the critical radius may be determined from the sound generated by the collision of two spheres in a viscous liquid. The technique is shown to provide a more precise and decisive indication of when hard spheres collide.

  13. Modelling of a collision between two smartphones

    NASA Astrophysics Data System (ADS)

    de Jesus, V. L. B.; Sasaki, D. G. G.

    2016-09-01

    In the predominant approach in physics textbooks, the collision between particles is treated as a black box, where no physical quantity can be measured. This approach becomes even more evident in experimental classes where collisions are the simplest and most common way of applying the theorem of conservation of linear momentum in the asymptotic behavior. In this paper we develop and analyse an experiment on collisions using only two smartphones. The experimental setup is amazingly simple; the two devices are aligned on a horizontal table of lacquered wood, in order to slide more easily. At the edge of one of them a piece of common sponge is glued using double-sided tape. By using a free smartphone application, the values generated by the accelerometer of the two devices in full motion are measured and tabulated. Through numerical iteration, the speed graphs of the smartphones before, during, and after the collision are obtained. The main conclusions were: (i) the demonstration of the feasibility of using smartphones as an alternative to air tracks and electronic sensors employed in a teaching lab, (ii) the possibility of investigating the collision itself, its characteristics and effects; this is the great advantage of the use of smartphones over traditional experiments, (iii) the compatibility of the results with the impulse-momentum theorem, within the margin of uncertainty.

  14. Underactuated spacecraft formation reconfiguration with collision avoidance

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Yan, Ye; Zhou, Yang

    2017-02-01

    Underactuated collision-free controllers are proposed in this paper for multiple spacecraft formation reconfiguration in circular orbits with the loss of either the radial or in-track thrust. A nonlinear dynamical model of underactuated formation flying is introduced, which is then linearized about circular orbits for controllability and feasibility analyses on underactuated formation reconfiguration. By using the inherent dynamics coupling of system states, reduced-order sliding mode controllers are then designed for either case to indirectly stabilize the system trajectories to the desired formations. In consideration of the collision-avoidance requirement, the artificial potential function method is then employed to design novel underactuated collision-avoidance maneuvers. Rigorous proof substantiates the capabilities of such maneuvers in preventing collisions even in the absence of radial or in-track thrust. Furthermore, a Lyapunov-based analysis ensures the asymptotic stability of the overall closed-loop system. Numerical simulations are performed in a J2-perturbed environment to verify the validity of the proposed underactuated control schemes for collision-free reconfiguration.

  15. Characteristics of Unequal Size Drop Collisions

    NASA Astrophysics Data System (ADS)

    Kim, Jungyong; Longmire, Ellen; Kim, Man Sik

    2009-11-01

    Pairs of water/glycerin drops were injected into silicone oil and traveled on downward trajectories before colliding. Unequal size drop collisions with drop size ratios (Ds/DL) of 0.7 and 0.5 were investigated. Simultaneous dual-field PIV measurements were obtained to characterize coalescence and rebounding behavior. The initial injection angle and tube height were adjusted to access appropriate impact parameters. In the current study, the collision angle of the large drop was, in general, shallower than that of the small drop, and a range of velocity ratios and impact parameters was examined. Coalescence occurs above We* = 11 similar to collision outcomes for equal size drops. As drop size ratio decreases, the intervening film deforms more. If the velocity ratio uL/us < 1, the interface remains deformed at coalescence, but if uL/us > 1, the interface flattens before coalescence. The rupture location varies due to the asymmetry of the drops. As collision offset increases (B > 0), the film rupture time is shortened and mixing of the fluid within the drops is enhanced after coalescence. These results will be compared with the behavior observed previously for equal size drop collisions.

  16. Collisions of solid ice in planetesimal formation

    NASA Astrophysics Data System (ADS)

    Deckers, J.; Teiser, J.

    2016-03-01

    We present collision experiments of centimetre projectiles on to decimetre targets, both made up of solid ice, at velocities of 15-45 m s-1 at an average temperature of {T_{avg}}=255.8 ± 0.7 K. In these collisions, the centimetre body gets disrupted and part of it sticks to the target. This behaviour can be observed up to an upper threshold, that depends on the projectile size, beyond which there is no mass transfer. In collisions of small particles, as produced by the disruption of the centimetre projectiles, we also find mass transfer to the target. In this way, the larger body can gain mass, although the efficiency of the initial mass transfer is rather low. These collision results can be applied to planetesimal formation near the snowline, where evaporation and condensation is expected to produce solid ice. In free fall collisions at velocities up to about 7 m s-1, we investigated the threshold to fragmentation and coefficient of restitution of centimetre ice spheres.

  17. Variational collision integrator for polymer chains

    NASA Astrophysics Data System (ADS)

    Leyendecker, Sigrid; Hartmann, Carsten; Koch, Michael

    2012-05-01

    The numerical simulation of many-particle systems (e.g. in molecular dynamics) often involves constraints of various forms. We present a symplectic integrator for mechanical systems with holonomic (bilateral) and unilateral contact constraints, the latter being in the form of a non-penetration condition. The scheme is based on a discrete variant of Hamilton's principle in which both the discrete trajectory and the unknown collision time are varied (cf. [R. Fetecau, J. Marsden, M. Ortiz, M. West, Nonsmooth Lagrangian mechanics and variational collision integrators, SIAM J. Appl. Dyn. Syst. 2 (2003) 381-416]). As a consequence, the collision event enters the discrete equations of motion as an unknown that has to be computed on-the-fly whenever a collision is imminent. The additional bilateral constraints are efficiently dealt with employing a discrete null space reduction (including a projection and a local reparametrisation step) which considerably reduces the number of unknowns and improves the condition number during each time-step as compared to a standard treatment with Lagrange multipliers. We illustrate the numerical scheme with a simple example from polymer dynamics, a linear chain of beads, and test it against other standard numerical schemes for collision problems.

  18. High energy hadron-hadron collisions

    NASA Astrophysics Data System (ADS)

    Chou, T. T.

    Results of a study on high energy collisions with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) e(sup +)e(sup (minus)) annihilation. For elastic scattering, a modified form for the hadronic matter form factor of the proton was proposed which is still dipole in form but contains an energy-dependent range parameter. This new expression of the opacity function fits the elastic (bar p)p scattering very well from the ISR to S(bar p)pS energies. Extrapolation of this theory also yielded results in good agreement with the (bar p)p differential cross section measured at the Tevatron. For inelastic hadron-hadron collisions, we have made a systematic investigation of the single-particle momentum spectra in the entire S(bar p)pS energy region. Results are useful for the extrapolation of angular distribution to the higher SSC energies. In e(sup +)e(sup (minus)) annihilation, a detailed analysis of all available experimental multiplicity data from PETRA to LEP energies has been performed. The cluster size of emitted hadrons increases gradually with energy. Aside from high-energy collisions, the giant fullerene molecules were studied and precise algebraic eigenvalue expressions of the Hueckel problem for carbon-240 were obtained.

  19. High energy hadron-hadron collisions

    SciTech Connect

    Chou, T.T.

    1990-11-01

    Results of a study on high energy collision with the geometrical model are summarized in three parts: (i) the elastic hadron-hadron collision, (ii) the inelastic hadron-hadron collision, and (iii) the e{sup +}e{sup {minus}} annihilation. For elastic collisions, a simple expression for the proton matter distribution is proposed which fits well the elastic {bar p}p scattering from ISR to S{bar p}pS energies within the geometrical model. The proton form factor is of the dipole form with an energy-dependent range parameter. The {bar p}p elastic differential cross section at Tevatron energies obtained by extrapolation is in good agreement with experiments. For multiparticle emission processes a unified physical picture for hadron-hadron and e{sup +}e{sup {minus}} collisions was proposed. A number of predictions were made, including the one that KNO-scaling does not obtain for e{sup +}e{sup {minus}} two-jet events. An extension of the considerations within the geometrical model led to a theory of the momentum distributions of the outgoing particles which are found in good agreement with current experimental data. Extrapolations of results to higher energies have been made. The cluster size of hadrons produced in e{sup +}e{sup {minus}} annihilation is found to increase slowly with energy.

  20. Measurements of Correlation-Enhanced Collision Rates

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Dubin, D. H. E.; O'Neil, T. M.; Driscoll, C. F.

    2008-11-01

    We measure the perp-to-parallel collision rate ν| in laser-cooled Magnesium ion plasmas in the strongly-magnetized and correlated regime; and obtain close agreement with the ``Salpeter correlation enhancement'' first studied for fusion in dense plasmas such as stars. The cyclotron energy, like nuclear energy, is released only through rare close-range collisions. These close collisions are suppressed by strong magnetization, because collisional impact distances are rarely as small as a cyclotron radius rc. However, theory predicts that particle correlations reduce this suppression of collisionality, enhancing the rare close collisions by e^γ, where γ≡e^2 / aT is the correlation parameter. We control the plasma temperature over the range 4 0-6 < T < 1eV, giving correlation parameters up to γ 0, with measured collision rates 2 < ν| 2 10^4 sec-1. At low temperatures, the measured ν| are enhanced by up to 10^9 compared to uncorrelated theory, consistent with the predicted correlation enhancement. When the plasma density is reduced from 2 to 0.12 x10^7cm-3, the correlations are eliminated and the measured ν| agree with uncorrelated theory. E.E. Salpeter and H.M. Van Horn, Astrophys. J. 155, 183 (1969). D.H.E. Dubin, Phys. Rev. Lett. 94, 025002 (2005).

  1. Bouncing and Merging of Liquid Jets

    NASA Astrophysics Data System (ADS)

    Saha, Abhishek; Li, Minglei; Law, Chung K.

    2014-11-01

    Collision of two fluid jets is a technique that is utilized in many industrial applications, such as in rocket engines, to achieve controlled mixing, atomization and sometimes liquid phase reactions. Thus, the dynamics of colliding jets have direct impact on the performance, efficiency and reliability of such applications. In analogy with the dynamics of droplet-droplet collision, in this work we have experimentally demonstrated, for n-alkane hydrocarbons as well as water, that with increasing impact inertia obliquely colliding jets also exhibit the same nonmonotonic responses of merging, bouncing, merging again, and merging followed by disintegration; and that the continuous entrainment of the boundary layer air over the jet surface into the colliding interfacial region leads to two distinguishing features of jet collision, namely: there exists a maximum impact angle beyond which merging is always possible, and that merging is inhibited and then promoted with increasing pressure. These distinct response regimes were mapped and explained on the bases of impact inertia, deformation of the jet surface, viscous loss within the jet interior, and the thickness and pressure build-up within the interfacial region in order to activate the attractive surface van der Waals force to effect merging.

  2. Liquid-liquid-solid transition in viscoelastic liquids

    PubMed Central

    Zubelewicz, Aleksander

    2013-01-01

    Liquid-liquid-solid transitions (LLST) are known to occur in confined liquids, exist in supercooled liquids and emerge in liquids driven from equilibrium. Molecular dynamics (MD) simulations claim many successes in forecasting the phenomena. The transitions are also studied in the framework of thermodynamics based methods and minimalistic models. In here, the proposed approach is derived in the framework of continuum and includes spatial and temporal dynamic heterogeneities; the approach is meant to capture the material behavior at small scales. We conjecture that the liquid-like and solid-like behaviors are dissimilar enough for the two to be governed by different constitutive relations. In this way, we gain additional degree of freedom, which is found essential when predicting the transitional phenomena. As a result, we derive the LLST criteria for liquids in equilibrium, during steady flow and at transient conditions. Lastly, we forecast short-lived LLSTs in human blood during cardiac cycle. PMID:23429528

  3. Viscous magnetoresistance of correlated electron liquids

    NASA Astrophysics Data System (ADS)

    Levchenko, Alex; Xie, Hong-Yi; Andreev, A. V.

    2017-03-01

    We develop a theory of magnetoresistance of two-dimensional electron systems in a smooth disorder potential in the hydrodynamic regime. Our theory applies to two-dimensional semiconductor structures with strongly correlated carriers when the mean free path due to electron-electron collisions is sufficiently short. The dominant contribution to magnetoresistance arises from the modification of the flow pattern by the Lorentz force, rather than the magnetic field dependence of the kinetic coefficients of the electron liquid. The resulting magnetoresistance is positive and quadratic at weak fields. Although the resistivity is governed by both the viscosity and thermal conductivity of the electron fluid, the magnetoresistance is controlled by the viscosity only. This enables the extraction of viscosity of the electron liquid from magnetotransport measurements.

  4. Liquid Crystal Devices.

    ERIC Educational Resources Information Center

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  5. Liquid Crystal Inquiries.

    ERIC Educational Resources Information Center

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  6. Thermal Conductivity of Spin-Polarized Liquid {sup 3}He

    SciTech Connect

    Sawkey, D.; Puech, L.; Wolf, P.E.

    2006-06-02

    We present the first measurements of the thermal conductivity of spin-polarized normal liquid {sup 3}He. Using the rapid melting technique to produce nuclear polarizations up to 0.7, and a vibrating wire both as a heater and a thermometer, we show that, unlike the viscosity, the conductivity increases much less than predicted for s-wave scattering. We suggest that this might be due to a small probability for head-on collisions between quasiparticles.

  7. Neutrino quantum kinetic equations: The collision term

    DOE PAGES

    Blaschke, Daniel N.; Cirigliano, Vincenzo

    2016-08-01

    We derive the collision term relevant for neutrino quantum kinetic equations in the early universe and compact astrophysical objects, displaying its full matrix structure in both flavor and spin degrees of freedom. We include in our analysis neutrino-neutrino processes, scattering and annihilation with electrons and positrons, and neutrino scattering off nucleons (the latter in the low-density limit). After presenting the general structure of the collision terms, we take two instructive limiting cases. The one-flavor limit highlights the structure in helicity space and allows for a straightforward interpretation of the off-diagonal entries in terms of the product of scattering amplitudes ofmore » the two helicity states. As a result, the isotropic limit is relevant for studies of the early universe: in this case the terms involving spin coherence vanish and the collision term can be expressed in terms of two-dimensional integrals, suitable for computational implementation.« less

  8. Chiral Magnetic Effect in Heavy Ion Collisions

    SciTech Connect

    Liao, Jinfeng

    2016-12-01

    The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. We show it is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields |Β|~m2π are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. Lastly, in this contribution we give a brief overview on the status of such efforts.

  9. Chiral Magnetic Effect in Heavy Ion Collisions

    DOE PAGES

    Liao, Jinfeng

    2016-12-01

    The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. We show it is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields |Β→|~m2π are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. Lastly, in this contribution we give a brief overview onmore » the status of such efforts.« less

  10. Collision-spike sputtering of Au nanoparticles

    SciTech Connect

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. As a result, the sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.

  11. Collision-spike sputtering of Au nanoparticles

    DOE PAGES

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; themore » remainder is transported away by the transmitted projectile and the ejecta. As a result, the sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.« less

  12. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

    We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

  13. Computations of Drop Collision and Coalescence

    NASA Technical Reports Server (NTRS)

    Tryggvason, Gretar; Juric, Damir; Nas, Selman; Mortazavi, Saeed

    1996-01-01

    Computations of drops collisions, coalescence, and other problems involving drops are presented. The computations are made possible by a finite difference/front tracking technique that allows direct solutions of the Navier-Stokes equations for a multi-fluid system with complex, unsteady internal boundaries. This method has been used to examine the various collision modes for binary collisions of drops of equal size, mixing of two drops of unequal size, behavior of a suspension of drops in linear and parabolic shear flows, and the thermal migration of several drops. The key results from these simulations are reviewed. Extensions of the method to phase change problems and preliminary results for boiling are also shown.

  14. Neutrino quantum kinetic equations: The collision term

    SciTech Connect

    Blaschke, Daniel N.; Cirigliano, Vincenzo

    2016-08-01

    We derive the collision term relevant for neutrino quantum kinetic equations in the early universe and compact astrophysical objects, displaying its full matrix structure in both flavor and spin degrees of freedom. We include in our analysis neutrino-neutrino processes, scattering and annihilation with electrons and positrons, and neutrino scattering off nucleons (the latter in the low-density limit). After presenting the general structure of the collision terms, we take two instructive limiting cases. The one-flavor limit highlights the structure in helicity space and allows for a straightforward interpretation of the off-diagonal entries in terms of the product of scattering amplitudes of the two helicity states. As a result, the isotropic limit is relevant for studies of the early universe: in this case the terms involving spin coherence vanish and the collision term can be expressed in terms of two-dimensional integrals, suitable for computational implementation.

  15. Hit-and-run planetary collisions.

    PubMed

    Asphaug, Erik; Agnor, Craig B; Williams, Quentin

    2006-01-12

    Terrestrial planet formation is believed to have concluded in our Solar System with about 10 million to 100 million years of giant impacts, where hundreds of Moon- to Mars-sized planetary embryos acquired random velocities through gravitational encounters and resonances with one another and with Jupiter. This led to planet-crossing orbits and collisions that produced the four terrestrial planets, the Moon and asteroids. But here we show that colliding planets do not simply merge, as is commonly assumed. In many cases, the smaller planet escapes from the collision highly deformed, spun up, depressurized from equilibrium, stripped of its outer layers, and sometimes pulled apart into a chain of diverse objects. Remnants of these 'hit-and-run' collisions are predicted to be common among remnant planet-forming populations, and thus to be relevant to asteroid formation and meteorite petrogenesis.

  16. Simulating Coulomb collisions in a magnetized plasma

    SciTech Connect

    Hinton, Fred L.

    2008-04-15

    The problem of simulating ion-ion Coulomb collisions in a plasma in a strong magnetic field is considered. No assumption is made about the ion distribution function except that it is independent of the gyrophase angle, consistent with the assumption that the ion gyrofrequency is much larger than the ion-ion collision frequency. A Langevin method is presented which time-advances the components of a particle's velocity parallel and perpendicular to the magnetic field, without following the rapidly changing gyrophase. Although the standard Monte Carlo procedure, which uses random sampling, can be used, it is also possible to use a deterministic sampling procedure, where the samples are determined by the points which would be used in a numerical quadrature formula for moments of the Fokker-Planck Green's function. This should reduce the sampling noise compared with the Monte Carlo collision method.

  17. Coefficient of restitution for a superelastic collision

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2017-03-01

    A simple experiment is described where the tip of a metal ruler is used to strike a 50 g mass. Since the ruler is very flexible, the impact duration is much longer than usual, giving the impression that the ruler simply pushes the mass forward at low speed over a long distance. The tip of the ruler remains in contact with the mass throughout the impact. However, the impact is best described as a long duration collision with a coefficient of restitution (COR) greater than zero, despite the fact that the relative speed during and at the end of the collision is zero. If the mass rests on a table and if the ruler strikes the table before striking the mass, then the ruler bends and stores elastic energy. The result is a superelastic collision where the COR is greater than unity.

  18. Active Collision Avoidance for Planetary Landers

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Hannan, Mike; Srinivasan, Karthik

    2014-01-01

    Present day robotic missions to other planets require precise, a priori knowledge of the terrain to pre-determine a landing spot that is safe. Landing sites can be miles from the mission objective, or, mission objectives may be tailored to suit landing sites. Future robotic exploration missions should be capable of autonomously identifying a safe landing target within a specified target area selected by mission requirements. Such autonomous landing sites must (1) 'see' the surface, (2) identify a target, and (3) land the vehicle. Recent advances in radar technology have resulted in small, lightweight, low power radars that are used for collision avoidance and cruise control systems in automobiles. Such radar systems can be adapted for use as active hazard avoidance systems for planetary landers. The focus of this CIF proposal is to leverage earlier work on collision avoidance systems for MSFC's Mighty Eagle lander and evaluate the use of automotive radar systems for collision avoidance in planetary landers.

  19. Rapidity dependence in holographic heavy ion collisions

    DOE PAGES

    Wilke van der Schee; Schenke, Bjorn

    2015-12-11

    We present an attempt to closely mimic the initial stage of heavy ion collisions within holography, assuming a decoupling of longitudinal and transverse dynamics in the very early stage. We subsequently evolve the obtained initial state using state-of-the-art hydrodynamic simulations and compare results with experimental data. We present results for charged hadron pseudorapidity spectra and directed and elliptic flow as functions of pseudorapidity for √sNN = 200GeV Au-Au and 2.76TeV Pb-Pb collisions. As a result, the directed flow interestingly turns out to be quite sensitive to the viscosity. The results can explain qualitative features of the collisions, but the rapiditymore » spectra in our current model is narrower than the experimental data.« less

  20. Rapidity dependence in holographic heavy ion collisions

    SciTech Connect

    Wilke van der Schee; Schenke, Bjorn

    2015-12-11

    We present an attempt to closely mimic the initial stage of heavy ion collisions within holography, assuming a decoupling of longitudinal and transverse dynamics in the very early stage. We subsequently evolve the obtained initial state using state-of-the-art hydrodynamic simulations and compare results with experimental data. We present results for charged hadron pseudorapidity spectra and directed and elliptic flow as functions of pseudorapidity for √sNN = 200GeV Au-Au and 2.76TeV Pb-Pb collisions. As a result, the directed flow interestingly turns out to be quite sensitive to the viscosity. The results can explain qualitative features of the collisions, but the rapidity spectra in our current model is narrower than the experimental data.

  1. Neutrino quantum kinetic equations: The collision term

    SciTech Connect

    Blaschke, Daniel N.; Cirigliano, Vincenzo

    2016-08-01

    We derive the collision term relevant for neutrino quantum kinetic equations in the early universe and compact astrophysical objects, displaying its full matrix structure in both flavor and spin degrees of freedom. We include in our analysis neutrino-neutrino processes, scattering and annihilation with electrons and positrons, and neutrino scattering off nucleons (the latter in the low-density limit). After presenting the general structure of the collision terms, we take two instructive limiting cases. The one-flavor limit highlights the structure in helicity space and allows for a straightforward interpretation of the off-diagonal entries in terms of the product of scattering amplitudes of the two helicity states. As a result, the isotropic limit is relevant for studies of the early universe: in this case the terms involving spin coherence vanish and the collision term can be expressed in terms of two-dimensional integrals, suitable for computational implementation.

  2. Collision-spike Sputtering of Au Nanoparticles.

    PubMed

    Sandoval, Luis; Urbassek, Herbert M

    2015-12-01

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.

  3. Tilting Uranus without a Collision

    NASA Astrophysics Data System (ADS)

    Rogoszinski, Zeeve; Hamilton, Douglas P.

    2016-10-01

    The most accepted hypothesis for the origin of Uranus' 98° obliquity is a giant collision during the late stages of planetary accretion. This model requires a single Earth mass object striking Uranus at high latitudes; such events occur with a probability of about 10%. Alternatively, Uranus' obliquity may have arisen from a sequence of smaller impactors which lead to a uniform distribution of obliquities. Here we explore a third model for tilting Uranus using secular spin-orbit resonance theory. We investigate early Solar System configurations in which a secular resonance between Uranus' axial precession frequency and another planet's orbital node precession frequency might occur.Thommes et al. (1999) hypothesized that Uranus and Neptune initially formed between Jupiter and Saturn, and were then kicked outward. In our scenario, Neptune leaves first while Uranus remains behind. As an exterior Neptune slowly migrates outward, it picks up both Uranus and Saturn in spin-orbit resonances (Ward and Hamilton 2004; Hamilton and Ward 2004). Only a distant Neptune has a nodal frequency slow enough to resonate with Uranus' axial precession.This scenario, with diverging orbits, results in resonance capture. As Neptune migrates outward its nodal precession slows. While in resonance, Uranus and Saturn each tilt a bit further, slowing their axial precession rates to continually match Neptune's nodal precession rate. Tilting Uranus to high obliquities takes a few 100 Myrs. This timescale may be too long to hold Uranus captive between Jupiter and Saturn, and we are investigating how to reduce it. We also find that resonance capture is rare if Uranus' initial obliquity is greater than about 10°, as the probability of capture decreases as the planet's initial obliquity increases. We will refine this estimate by quantifying capture statistics, and running accretion simulations to test the likelihood of a low early obliquity. Our preliminary findings show that most assumptions about

  4. Modeling of collision and coalescence of droplets during microgravity processing of Zn-Bi immiscible alloys

    NASA Technical Reports Server (NTRS)

    Davis, R. H.; Rogers, J. R.

    1990-01-01

    A population balance model is presented for the coarsening of the dispersed phase of liquid-liquid two-phase mixtures in microgravity due to gravity sedimentation and Marangoni migration, which lead to the collision and coalescence of droplets. The model is used to predict the evolution of the size distribution of the dispersed phase in a liquid-phase miscibility gap system, Zn-Bi, which has been used in a number of experimental microgravity processing studies in which significant phase segregation has been observed. The analysis shows that increasing the temperature gradient, gravity level, volume fraction of the dispersed phase, initial average drop radius, initial standard deviation of droplet radii, or the temperature coefficient of the interfacial tension leads to an increase in the rate of droplet growth due to collision and coalescence. Comparison of the distribution evolutions for unimodal and bimodal initial distributions shows that the latter yield significantly more rapid droplet growth. Finally, it is shown that droplet growth can be dramatically reduced with antiparallel orientation of the gravity vector and the temperature gradient, provided that the relative magnitude of these two vectors is properly chosen.

  5. Coincidence studies of ion-molecule collisions

    NASA Astrophysics Data System (ADS)

    Ben-Itzhak, Itzik

    1998-05-01

    Two of the simplest collision systems one can imagine are H^+ + H(1s) and H^+ + D(1s). Electron transfer is resonant in the first and nearly resonant in the latter because of the 3.7 meV gap between the H(1s) and D(1s). Once the collision velocity becomes small enough quantum effects become more pronounced and the electron transfer rate as a function of collision energy exhibits many resonances(G. Hunter and M. Kuriyan, Proc. Roy. Soc. Lond. A 358), 321 (1977).^,(J.P. Davis and W.R. Thorson, Can. J. Phys. 56), 996 (1978).. However, most of the interesting features appear at very low energies, of a few meV, and these collision systems which are the ``theorist's dream'' become a nightmare to experimentalists. Nevertheless, we are undertaking the challenging measurement of near resonant electron transfer in the H^+ + D(1s) collision system. When a HD molecule is ionized quickly, such that the transition to the HD^+ molecular ion is vertical, about 1% of the HD^+(1sσ) is in the vibrational continuum. The transition probability falls off approximately exponentially above threshold and its width is about 200 meV. During the dissociation, the electron initially centered on the D core can make a transition to the H core when the 2pσ and 1sσ potential energy curves associated with the two dissociation limits get close to each other. It is important to note that during molecular dissociation the ``avoided crossing'' is crossed only once in contrast to twice during a full collision. Using a localized cold HD target and 3D imaging of the low energy H^+ and D^+ dissociation fragments one can experimentally determine the transition probability between these two states as a function of the dissociation energy. Clearly, a recoil energy resolution of the order of a meV is necessary, which is the primary experimental challenge.

  6. Early hydrodynamic evolution of a stellar collision

    SciTech Connect

    Kushnir, Doron; Katz, Boaz

    2014-04-20

    The early phase of the hydrodynamic evolution following the collision of two stars is analyzed. Two strong shocks propagate from the contact surface and move toward the center of each star at a velocity that is a small fraction of the velocity of the approaching stars. The shocked region near the contact surface has a planar symmetry and a uniform pressure. The density vanishes at the (Lagrangian) surface of contact, and the speed of sound diverges there. The temperature, however, reaches a finite value, since as the density vanishes, the finite pressure is radiation dominated. For carbon-oxygen white dwarf (CO WD) collisions, this temperature is too low for any appreciable nuclear burning shortly after the collision, which allows for a significant fraction of the mass to be highly compressed to the density required for efficient {sup 56}Ni production in the detonation wave that follows. This property is crucial for the viability of collisions of typical CO WD as progenitors of type Ia supernovae, since otherwise only massive (>0.9 M {sub ☉}) CO WDs would have led to such explosions (as required by all other progenitor models). The divergence of the speed of sound limits numerical studies of stellar collisions, as it makes convergence tests exceedingly expensive unless dedicated schemes are used. We provide a new one-dimensional Lagrangian numerical scheme to achieve this. A self-similar planar solution is derived for zero-impact parameter collisions between two identical stars, under some simplifying assumptions (including a power-law density profile), which is the planar version of previous piston problems that were studied in cylindrical and spherical symmetries.

  7. Collision statistics in sheared inelastic hard spheres.

    PubMed

    Bannerman, Marcus N; Green, Thomas E; Grassia, Paul; Lue, Leo

    2009-04-01

    The dynamics of sheared inelastic-hard-sphere systems is studied using nonequilibrium molecular-dynamics simulations and direct simulation Monte Carlo. In the molecular-dynamics simulations Lees-Edwards boundary conditions are used to impose the shear. The dimensions of the simulation box are chosen to ensure that the systems are homogeneous and that the shear is applied uniformly. Various system properties are monitored, including the one-particle velocity distribution, granular temperature, stress tensor, collision rates, and time between collisions. The one-particle velocity distribution is found to agree reasonably well with an anisotropic Gaussian distribution, with only a slight overpopulation of the high-velocity tails. The velocity distribution is strongly anisotropic, especially at lower densities and lower values of the coefficient of restitution, with the largest variance in the direction of shear. The density dependence of the compressibility factor of the sheared inelastic-hard-sphere system is quite similar to that of elastic-hard-sphere fluids. As the systems become more inelastic, the glancing collisions begin to dominate over more direct, head-on collisions. Examination of the distribution of the times between collisions indicates that the collisions experienced by the particles are strongly correlated in the highly inelastic systems. A comparison of the simulation data is made with direct Monte Carlo simulation of the Enskog equation. Results of the kinetic model of Montanero [J. Fluid Mech. 389, 391 (1999)] based on the Enskog equation are also included. In general, good agreement is found for high-density, weakly inelastic systems.

  8. Affordable MMW aircraft collision avoidance system

    NASA Astrophysics Data System (ADS)

    Almsted, Larry D.; Becker, Robert C.; Zelenka, Richard E.

    1997-06-01

    Collision avoidance is of concern to all aircraft, requiring the detection and identification of hazardous terrain or obstacles in sufficient time for clearance maneuvers. The collision avoidance requirement is even more demanding for helicopters, as their unique capabilities result in extensive operations at low-altitude, near to terrain and other hazardous obstacles. TO augment the pilot's visual collision avoidance abilities, some aircraft are equipped with 'enhanced-vision' systems or terrain collision warning systems. Enhanced-vision systems are typically very large and costly systems that are not very covert and are also difficult to install in a helicopter. The display is typically raw images from infrared or radar sensors, and can require a high degree of pilot interpretation and attention. Terrain collision warning system that rely on stored terrain maps are often of low resolution and accuracy and do not represent hazards to the aircraft placed after map sampling. Such hazards could include aircraft parked on runway, man- made towers or buildings and hills. In this paper, a low cost dual-function scanning pencil-beam, millimeter-wave radar forward sensor is used to determine whether an aircraft's flight path is clear of obstructions. Due to the limited space and weight budget in helicopters, the system is a dual function system that is substituted in place of the existing radar altimeter. The system combines a 35 GHz forward looking obstacle avoidance radar and a 4.3 GHz radar altimeter. The forward looking 35 GHz 3D radar's returns are used to construct a terrain and obstruction database surrounding an aircraft, which is presented to the pilot as a synthetic perspective display. The 35 GHz forward looking radar and the associated display was evaluated in a joint NASA Honeywell flight test program in 1996. The tests were conducted on a NASA/Army test helicopter. The test program clearly demonstrated the systems potential usefulness for collision avoidance.

  9. REDISTRIBUTOR FOR LIQUID-LIQUID EXTRACTION COLUMNS

    DOEpatents

    Bradley, J.G.

    1957-10-29

    An improved baffle plate construction to intimately mix immiscible liquid solvents for solvent extraction processes in a liquid-liquid pulse column is described. To prevent the light and heavy liquids from forming separate continuous homogeneous vertical channels through sections of the column, a baffle having radially placed rectangular louvers with deflection plates opening upon alternate sides of the baffle is placed in the column, normal to the axis. This improvement substantially completely reduces strippiig losses due to poor mixing.

  10. Newton's cradle undone: Experiments and collision models for the normal collision of three solid spheres

    NASA Astrophysics Data System (ADS)

    Donahue, C. M.; Hrenya, C. M.; Zelinskaya, A. P.; Nakagawa, K. J.

    2008-11-01

    Using an apparatus inspired by Newton's cradle, the simultaneous, normal collision between three solid spheres is examined. Namely, an initially touching, motionless pair of "target" particles (doublet) is impacted on one end by a third "striker" particle. Measurements of postcollisional velocities and collision durations are obtained via high-speed photography and an electrical circuit, respectively. Contrary to intuition, the expected Newton's cradle outcome of a motionless, touching particle pair at the bottom of the pendulum arc is not observed in either case. Instead, the striker particle reverses its direction and separates from the middle particle after collision. This reversal is not observed, however, if the target particles are separated by a small distance (not in contact) initially, although a separation still occurs between the striker and middle particle after the collision, with both particles traveling in the same direction. For the case of initially touching target particles, contact duration measurements indicate that the striker separates from the three particles before the two target particles separate. However, when the targets are slightly separated, a three-particle collision is never observed, and the collision is, in fact, a series of two-body collisions. A subsequent implementation of a variety of hard-sphere and soft-sphere collision models indicates that a three-body (soft-sphere) treatment is essential for predicting the velocity reversal, consistent with the experimental findings. Finally, a direct comparison between model predictions and measurements of postcollisional velocities and contact durations provides a gauge of the relative merits of existing collision models for three-body interactions.

  11. Partial coalescence of sessile drops with different liquids

    NASA Astrophysics Data System (ADS)

    Borcia, Rodica; Bestehorn, Michael

    2014-11-01

    We examine numerically the interaction between two deformable drops consisting of two perfectly miscible liquids sitting on a solid substrate under a given contact angle. Driven by solutal Marangoni forces, several distinct coalescence regimes are achieved after the droplets collision. Phase diagrams for different control parameters are emphasized, which give predictions about drop behavior along the solid substrates, control of various interfacial effects, manipulations of tiny droplets in micro- and nano-fluidic devices without power supply, design of droplets or cleaning surfaces. This work was partially supported by Deutsche Forschungsgemeinschaft (DFG) under the project ``Dynamics of interfaces between drops with miscible liquids''.

  12. Collision detection and untangling for surgical robotic manipulators.

    PubMed

    Morvan, Tangui; Martinsen, Magnar; Reimers, Martin; Samset, Eigil; Elle, Ole Jakob

    2009-09-01

    Robotic-assisted minimally invasive surgery provides several advantages over traditional surgery; however, it also has several drawbacks, such as possible collisions between the robotic arms and a limited field of view. A generic method for tracking the configuration of a surgical manipulator in real time is presented. It is coupled with a collision detection and dynamic simulation algorithm, allowing the operator to detect collisions between robotic arms before they happen and presenting the best possible untangling direction to get out of collisions. Our algorithm successfully tracks the configuration of the Zeus surgical system and accurately detects possible collisions in real time. A pilot study on our system proved its efficiency in reducing the duration and severity of collisions, at the price of longer completion times. Our system helps alleviate the collision problem by reducing the time in collision.

  13. GEO Collision Avoidance using a Service Vehicle

    NASA Astrophysics Data System (ADS)

    Duncan, M.; Concha, M.

    2013-09-01

    Space Situational Awareness (SSA) is defined as the knowledge and characterization of all aspects of space. SSA is now a fundamental and critical component of space operations. The increased dependence on our space assets has in turn lead to a greater need for accurate, near real-time knowledge of all space activities. Key areas of SSA include improved tracking of small objects, determining the intent of maneuvering spacecraft, identifying all potential high risk conjunction events, and leveraging non-traditional sensors in support of the SSA mission. As the size of the space object population grows, the number of collision avoidance maneuvers grows. Moreover, as the SSA mission evolves to near real-time assessment and analysis, the need for new, more sophisticated collision avoidance methods are required. This paper demonstrates the utility of using a service vehicle to perform collision avoidance maneuver for GEO satellites. We present the planning and execution details required to successfully execute a maneuver; given the traditional conjunction analysis timelines. Various operational constraints and scenarios are considered as part of the demonstration. Development of the collision avoidance strategy is created using SpaceNav's collision risk management tool suite. This study aims to determine the agility required of any proposed servicing capability to provide collision avoidance within traditional conjunction analysis and collision avoidance operations timelines. Key trades and analysis items are given to be: 1. How do we fuse the spacecraft state data with the tracking data collected from the proximity sensor that resides on the servicing spacecraft? 2. How do we deal with the possibility that the collision threat for the event may change as the time to close approach is reduced? 3. Perform trade space of maneuver/thrust time versus achievable change in the spacecraft's orbit. 4. Perform trade space of proximity of service vehicle to spacecraft versus time

  14. Intelligent Sensor Tasking for Space Collision Mitigation

    SciTech Connect

    Olivier, S S; Pertica, A J; Henderson, J R

    2010-04-01

    Orbital collisions pose a hazard to space operations. Using a high performance computer modeling and simulation environment for space situational awareness, we explore a new paradigm for improving satellite conjunction analysis by obtaining more precise orbital information only for those objects that pose a collision risk greater than a defined threshold to a specific set of satellites during a specified time interval. In particular, we assess the improvement in the quality of the conjunction analysis that can be achieved using a distributed network of ground-based telescopes.

  15. High energy particle collisions near black holes

    NASA Astrophysics Data System (ADS)

    Zaslavskii, O. B.

    2016-10-01

    If two geodesic particles collide near a rotating black hole, their energy in the centre of mass frame Ec.m. can become unbound under certain conditions (the so-called BSW effect). The special role is played here by so-called critical geodesics when one of particles has fine-tuned energy and angular momentum. The nature of geodesics reveals itself also in fate of the debris after collisions. One of particles moving to a remote observer is necessarily near-critical. We discuss, when such a collision can give rise not only unboud Ec.m. but also unbound Killing energy E (so-called super-Penrose process).

  16. Angular spectrum analysis in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Llanes-Estrada, Felipe J.; Muñoz Martínez, Jose L.

    2017-01-01

    Heavy Ion Collisions serve to study some features of early-universe cosmology. In this contribution we adapt data analysis frequently used to understand the Cosmic Microwave Background anisotropies (such as the Mollweide projection and the angular power spectrum) to heavy ion collisions at the LHC. We examine a few publicly available events of the ALICE collaboration under this light. Because the ALICE time projection chamber has limited coverage in rapidity and some blind angles in the transverse plane, the angular spectrum seems very influenced by the detector's acceptance.

  17. Collision avoidance for CTV: Requirements and capabilities

    NASA Technical Reports Server (NTRS)

    Nosek, Thomas; Rourke, Kenneth

    1991-01-01

    Collision avoidance must be ensured during Cargo Transfer Vehicle (CTV) operations near the space station. The design of the Collision Avoidance Maneuver (CAM) will involve analysis of CTV failure modes during rendezvous and proximity operations as well as analysis of possible problems external to the CTV, but that would require CTV to execute a CAM. In considering the requirements and design of the CAM for the CTV, the CAM design for the Orbital Maneuvering Vehicle (OMV) is a useful reference point from which some lessons can be learned and many CTV design options can be set forth.

  18. Collision avoidance for CTV: Requirements and capabilities

    NASA Astrophysics Data System (ADS)

    Nosek, Thomas; Rourke, Kenneth

    Collision avoidance must be ensured during Cargo Transfer Vehicle (CTV) operations near the space station. The design of the Collision Avoidance Maneuver (CAM) will involve analysis of CTV failure modes during rendezvous and proximity operations as well as analysis of possible problems external to the CTV, but that would require CTV to execute a CAM. In considering the requirements and design of the CAM for the CTV, the CAM design for the Orbital Maneuvering Vehicle (OMV) is a useful reference point from which some lessons can be learned and many CTV design options can be set forth.

  19. Automobile Collisions, Kinematics and Related Injury Patterns

    PubMed Central

    Siegel, A. W.

    1972-01-01

    It has been determined clinically that fatalities and injury severity resulting from automobile collisions have decreased during the last five years for low impact speeds. This reduction is a direct result of the application of biomechanics and occupant kinematics, as well as changes in automobile design. The paper defines terminology used in the field of mechanics and develops examples and illustrations of the physical concepts of acceleration, force strength, magnitude duration, rate of onset and others, as they apply to collision phenomena and injury. The mechanism of injury pattern reduction through the use of restraint systems is illustrated. PMID:5059661

  20. A numerical 4D Collision Risk Model

    NASA Astrophysics Data System (ADS)

    Schmitt, Pal; Culloch, Ross; Lieber, Lilian; Kregting, Louise

    2017-04-01

    With the growing number of marine renewable energy (MRE) devices being installed across the world, some concern has been raised about the possibility of harming mobile, marine fauna by collision. Although physical contact between a MRE device and an organism has not been reported to date, these novel sub-sea structures pose a challenge for accurately estimating collision risks as part of environmental impact assessments. Even if the animal motion is simplified to linear translation, ignoring likely evasive behaviour, the mathematical problem of establishing an impact probability is not trivial. We present a numerical algorithm to obtain such probability distributions using transient, four-dimensional simulations of a novel marine renewable device concept, Deep Green, Minesto's power plant and hereafter referred to as the 'kite' that flies in a figure-of-eight configuration. Simulations were carried out altering several configurations including kite depth, kite speed and kite trajectory while keeping the speed of the moving object constant. Since the kite assembly is defined as two parts in the model, a tether (attached to the seabed) and the kite, collision risk of each part is reported independently. By comparing the number of collisions with the number of collision-free simulations, a probability of impact for each simulated position in the cross- section of the area is considered. Results suggest that close to the bottom, where the tether amplitude is small, the path is always blocked and the impact probability is 100% as expected. However, higher up in the water column, the collision probability is twice as high in the mid line, where the tether passes twice per period than at the extremes of its trajectory. The collision probability distribution is much more complex in the upper end of the water column, where the kite and tether can simultaneously collide with the object. Results demonstrate the viability of such models, which can also incorporate empirical

  1. Nonrelativistic theory of heavy-ion collisions

    SciTech Connect

    Bertsch, G.

    1984-07-17

    A wide range of phenomena is observed in heavy-ion collisions, calling for a comprehensive theory based on fundamental principles of many-particle quantum mechanics. At low energies, the nuclear dynamics is controlled by the mean field, as we know from spectroscopic nuclear physics. We therefore expect the comprehensive theory of collisions to contain mean-field theory at low energies. The mean-field theory is the subject of the first lectures in this chapter. This theory can be studied quantum mechanically, in which form it is called TDHF (time-dependent Hartree-Fock), or classically, where the equation is called the Vlasov equation. 25 references, 14 figures.

  2. Simplest piston problem. II. Inelastic collisions.

    PubMed

    Hurtado, Pablo I; Redner, S

    2006-01-01

    We study the dynamics of three particles in a finite interval, in which two light particles are separated by a heavy "piston," with elastic collisions between particles but inelastic collisions between the light particles and the interval ends. A symmetry breaking occurs in which the piston migrates near one end of the interval and performs small-amplitude periodic oscillations on a logarithmic time scale. The properties of this dissipative limit cycle can be understood simply in terms of a effective restitution coefficient picture. Many dynamical features of the three-particle system closely resemble those of the many-body inelastic piston problem.

  3. Holographic collisions in non-conformal theories

    NASA Astrophysics Data System (ADS)

    Attems, Maximilian; Casalderrey-Solana, Jorge; Mateos, David; Santos-Oliván, Daniel; Sopuerta, Carlos F.; Triana, Miquel; Zilhão, Miguel

    2017-01-01

    We numerically simulate gravitational shock wave collisions in a holographic model dual to a non-conformal four-dimensional gauge theory. We find two novel effects associated to the non-zero bulk viscosity of the resulting plasma. First, the hydrodynamization time increases. Second, if the bulk viscosity is large enough then the plasma becomes well described by hydrodynamics before the energy density and the average pressure begin to obey the equilibrium equation of state. We discuss implications for the quark-gluon plasma created in heavy ion collision experiments.

  4. Isotope effect in ion-atom collisions

    SciTech Connect

    Barragan, P.; Errea, L. F.; Mendez, L.; Rabadan, I.

    2010-09-15

    We explain the origin of the unusual large isotopic dependence found in charge-transfer cross sections for H(D,T){sup +}+Be collisions. We show that this large effect appears in a semiclassical treatment as a consequence of the mass dependence of the charge-transfer transition probabilities, which is due to the variation of the radial velocity in the region where the nonadiabatic transitions take place. The possibility of finding such a large isotope effect in other collision systems is discussed.

  5. Sodiation-based in-source collision for profiling of pyranocoumarins in Radix Peucedani (Qianhu): utility of sodium adducts' stability with in-source collision.

    PubMed

    Yang, W; Li, Y; Kang, C; Zhao, H; Xiang, L; Li, C; Wang, Q

    2017-03-01

    Full scan mode of liquid chromatography-mass spectrometry equipped with an electrospray ionization source offers a chance on global detection of complicated components; however, the scan mode carries significant challenges in rapidly capturing information of analysts. Sodiation-based in-source collision was proposed here, as a technique for rapid detecting untargeted analytes in full scan analysis, which was based on the stability of sodium adducts and the nonselectivity of in-source collision. Then the technique was applied to profile of angular-type pyranocoumarins (APs) in Radix Peucedani, with full scan analysis performed at two specific in-source collision energy: a high energy 50 V that is tolerated by the sodium adducts of APs, and a low energy 10 V, at which abundant adducts were offered. The spectra list of two average mass spectra was exported, and stable ions were selected based on the intensity ratio of standards at the two collision energy. Then 27 plausible [M + Na](+) m/z values of APs were acquired after filtering the fragment ion and isotope ions and validating with [M + NH4 ](+) . Eighty-two APs finally were tentatively identified based on their accurate spectral data of MS(n) , fragmentation rules, and elution order regardless of their absolute configuration, which included 25 reported APs from Peucedanum praeruptorum Dunn. The technique provided a novel application of sodium adduct in qualitative analysis. And it was valuable for rapidly capturing information of analytes in full scan analysis, not only for APs but also for other compounds that could form sodium adducts. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Octree Bin-to-Bin Fractional-NTC Collisions

    DTIC Science & Technology

    2015-09-17

    Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 OCTREE BIN-TO-BIN FRACTIONAL-NTC COLLISIONS Robert Martin ERC INC., SPACECRAFT PROPULSION ...Important Collisions in Spacecraft Propulsion : Discharge and Breakdown in FRC Collisional Radiative Cooling/Ionization Combustion Chemistry Common Features...PUBLIC RELEASE 3 / 15 IMPORTANCE OF COLLISION PHYSICS Important Collisions in Spacecraft Propulsion : Discharge and Breakdown in FRC Collisional

  7. Fluid Dynamics of Bubbly Liquids

    NASA Technical Reports Server (NTRS)

    Tsang, Y. H.; Koch, D. L.; Zenit, R.; Sangani, A.; Kushch, V. I.; Spelt, P. D. M.; Hoffman, M.; Nahra, H.; Fritz, C.; Dolesh, R.

    2002-01-01

    Experiments have been performed to study the average flow properties of inertially dominated bubbly liquids which may be described by a novel analysis. Bubbles with high Reynolds number and low Weber number may produce a fluid velocity disturbance that can be approximated by a potential flow. We studied the behavior of suspensions of bubbles of about 1.5 mm diameter in vertical and inclined channels. The suspension was produced using a bank of 900 glass capillaries with inner diameter of about 100 microns in a quasi-steady fashion. In addition, salt was added to the suspension to prevent bubble-bubble coalescence. As a result, a nearly monodisperse suspension of bubble was produced. By increasing the inclination angle, we were able to explore an increasing amount of shear to buoyancy motion. A pipe flow experiment with the liquid being recirculated is under construction. This will provide an even larger range of shear to buoyancy motion. We are planning a microgravity experiment in which a bubble suspension is subjected to shearing in a couette cell in the absence of a buoyancy-driven relative motion of the two phases. By employing a single-wire, hot film anemometer, we were able to obtain the liquid velocity fluctuations. The shear stress at the wall was measured using a hot film probe flush mounted on the wall. The gas volume fraction, bubble velocity, and bubble velocity fluctuations were measured using a homemade, dual impedance probe. In addition, we also employed a high-speed camera to obtain the bubble size distribution and bubble shape in a dilute suspension. A rapid decrease in bubble velocity for a dilute bubble suspension is attributed to the effects of bubble-wall collisions. The more gradual decrease of bubble velocity as gas volume fraction increases, due to subsequent hindering of bubble motion, is in qualitative agreement with the predictions of Spelt and Sangani for the effects of potential-flow bubble-bubble interactions on the mean velocity. The

  8. Fluid Dynamics of Bubbly Liquids

    NASA Technical Reports Server (NTRS)

    Tsang, Y. H.; Koch, D. L.; Zenit, R.; Sangani, A.; Kushch, V. I.; Spelt, P. D. M.; Hoffman, M.; Nahra, H.; Fritz, C.; Dolesh, R.

    2002-01-01

    Experiments have been performed to study the average flow properties of inertially dominated bubbly liquids which may be described by a novel analysis. Bubbles with high Reynolds number and low Weber number may produce a fluid velocity disturbance that can be approximated by a potential flow. We studied the behavior of suspensions of bubbles of about 1.5 mm diameter in vertical and inclined channels. The suspension was produced using a bank of 900 glass capillaries with inner diameter of about 100 microns in a quasi-steady fashion. In addition, salt was added to the suspension to prevent bubble-bubble coalescence. As a result, a nearly monodisperse suspension of bubble was produced. By increasing the inclination angle, we were able to explore an increasing amount of shear to buoyancy motion. A pipe flow experiment with the liquid being recirculated is under construction. This will provide an even larger range of shear to buoyancy motion. We are planning a microgravity experiment in which a bubble suspension is subjected to shearing in a couette cell in the absence of a buoyancy-driven relative motion of the two phases. By employing a single-wire, hot film anemometer, we were able to obtain the liquid velocity fluctuations. The shear stress at the wall was measured using a hot film probe flush mounted on the wall. The gas volume fraction, bubble velocity, and bubble velocity fluctuations were measured using a homemade, dual impedance probe. In addition, we also employed a high-speed camera to obtain the bubble size distribution and bubble shape in a dilute suspension. A rapid decrease in bubble velocity for a dilute bubble suspension is attributed to the effects of bubble-wall collisions. The more gradual decrease of bubble velocity as gas volume fraction increases, due to subsequent hindering of bubble motion, is in qualitative agreement with the predictions of Spelt and Sangani for the effects of potential-flow bubble-bubble interactions on the mean velocity. The

  9. Analysing Collisions Using Minkowski Diagrams in Momentum Space

    ERIC Educational Resources Information Center

    Bokor, Nandor

    2011-01-01

    Momentum space and Minkowski diagrams are powerful tools for interpreting and analysing relativistic collisions in one or two spatial dimensions. All relevant quantities that characterize a collision, including the mass, velocity, momentum and energy of the interacting particles, both before and after collision, can be directly seen from a single…

  10. 14 CFR 121.356 - Collision avoidance system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Collision avoidance system. 121.356 Section... Collision avoidance system. Effective January 1, 2005, any airplane you operate under this part must be equipped and operated according to the following table: Collision Avoidance Systems If you operate...

  11. 14 CFR 125.224 - Collision avoidance system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Collision avoidance system. 125.224 Section... Requirements § 125.224 Collision avoidance system. Effective January 1, 2005, any airplane you operate under this part 125 must be equipped and operated according to the following table: Collision...

  12. 14 CFR 417.231 - Collision avoidance analysis.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Collision avoidance analysis. 417.231..., DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.231 Collision avoidance analysis. (a) General. A flight safety analysis must include a collision avoidance analysis...

  13. 14 CFR 437.65 - Collision avoidance analysis.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Collision avoidance analysis. 437.65..., DEPARTMENT OF TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Safety Requirements § 437.65 Collision avoidance... permittee must obtain a collision avoidance analysis from United States Strategic Command. (b) The...

  14. Meson multiplicity versus energy in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Atwater, T. W.; Freier, P. S.

    1986-01-01

    A systematic study of meson multiplicity as a function of energy at energies up to 100 GeV/u in nucleus-nucleus collisions has been made, using cosmic-ray data in nuclear emulsion. The data are consistent with simple nucleon-nucleon superposition models. Multiplicity per interacting nucleon in AA collisions does not appear to differ significantly from pp collisions.

  15. Analysing Collisions Using Minkowski Diagrams in Momentum Space

    ERIC Educational Resources Information Center

    Bokor, Nandor

    2011-01-01

    Momentum space and Minkowski diagrams are powerful tools for interpreting and analysing relativistic collisions in one or two spatial dimensions. All relevant quantities that characterize a collision, including the mass, velocity, momentum and energy of the interacting particles, both before and after collision, can be directly seen from a single…

  16. Do nuclear collisions create a locally equilibrated quark–gluon plasma?

    DOE PAGES

    Romatschke, P.

    2017-01-10

    Experimental results on azimuthal correlations in high energy nuclear collisions (nucleus–nucleus, proton–nucleus, and proton–proton) seem to be well described by viscous hydrodynamics. It is often argued that this agreement implies either local thermal equilibrium or at least local isotropy. In this note, I present arguments why this is not the case. Neither local near-equilibrium nor near-isotropy are required in order for hydrodynamics to offer a successful and accurate description of experimental results. However, I predict the breakdown of hydrodynamics at momenta of order seven times the temperature, corresponding to a smallest possible QCD liquid drop size of 0.15 fm.

  17. High energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Wosiek, B.

    1986-01-01

    Experimental results on high energy nucleus-nucleus interactions are presented. The data are discussed within the framework of standard super-position models and from the point-of-view of the possible formation of new states of matter in heavy ion collisions.

  18. High energy photon-photon collisions

    SciTech Connect

    Brodsky, S.J.; Zerwas, P.M.

    1994-07-01

    The collisions of high energy photons produced at a electron-positron collider provide a comprehensive laboratory for testing QCD, electroweak interactions and extensions of the standard model. The luminosity and energy of the colliding photons produced by back-scattering laser beams is expected to be comparable to that of the primary e{sup +}e{sup {minus}} collisions. In this overview, we shall focus on tests of electroweak theory in photon-photon annihilation, particularly {gamma}{gamma} {yields} W{sup +}W{sup {minus}}, {gamma}{gamma} {yields} Higgs bosons, and higher-order loop processes, such as {gamma}{gamma} {yields} {gamma}{gamma}, Z{gamma} and ZZ. Since each photon can be resolved into a W{sup +}W{sup minus} pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. We also review high energy {gamma}{gamma} tests of quantum chromodynamics, such as the scaling of the photon structure function, t{bar t} production, mini-jet processes, and diffractive reactions.

  19. Super high energy heavy ion collisions

    SciTech Connect

    Geist, W.M.

    1987-12-01

    Basic theoretical ideas on a phase transition to a plasma of free quarks and gluons in heavy ion collisions are outlined. First results from experiments with oxygen beams at 14.5 GeV/c/N (BNL), 60 and 200 GeV/c/N (CERN) are discussed. 30 refs., 9 figs.

  20. Sudden Hadronization in Relativistic Nuclear Collisions

    SciTech Connect

    Rafelski, Johann; Letessier, Jean

    2000-11-27

    We formulate and study a mechanical instability criterion for sudden hadronization of dense matter fireballs formed in 158A GeV Pb-Pb collisions. Considering properties of quark-gluon matter and hadron gas we obtain the phase boundary between these two phases and demonstrate that the required deep quark-gluon-plasma supercooling prior to sudden hadronization has occurred.

  1. Heavy quark production in pp collisions

    SciTech Connect

    McGaughey, P.L.; Quack, E.; Ruuskanen, P.V. |

    1995-07-01

    A systematic study of the inclusive single heavy quark and heavy-quark pair production cross sections in pp collisions is presented for RHIC and LHC energies. We compare with existing data when possible. The dependence of the rates on the renormalization and factorization scales is discussed. Predictions of the cross sections are given for two different sets of parton distribution functions.

  2. High-Velocity Collisions of Nanoparticles

    NASA Astrophysics Data System (ADS)

    Johnson, Donald; Mattson, William

    Nanoparticles (NPs) are interesting materials with exciting applications due to their large surface-to-volume ratio and functionalizable surfaces. The large surface area and potentially high surface tension might result in unique materials behavior when subject to shock loading. Using density functional theory, we have simulated high-velocity NP collisions producing high-pressure, high-temperature, and extreme shock conditions. NPs composed of diamond-C, cubic-BN, and diamond-Si were considered with particle sizes up to 3.5 nm diameter. Some simulations involved NPs that were destabilized by incorporating internal strain. Normal, spherical NPs were carved out of bulk crystals and structurally optimized while the NPs with internal strain were constructed as a dense core (compressive strain) encompassed by a thin shell (tensile strain). Both on-axis and off-axis collisions were simulated at various speeds. Collision dynamics, shock propagation, and fragmentation will be presented and analyzed. The effect of material properties, internal strain, and collision velocity on the final temperature of the fragments will be discussed.

  3. Computations of drop collision and coalescence

    NASA Technical Reports Server (NTRS)

    Tryggvason, Gretar; Juric, Damir; Nobari, Mohammed H. R.; Nas, Selman

    1994-01-01

    Computations of drops collision and coalescence are presented. The computations are made possible by a recently developed finite difference/front tracking technique that allows direct solutions of the Navier-Stokes equations for a multi-fluid system with complex, unsteady internal boundaries. This method has been used to examine the boundaries between the various collision modes for drops of equal size and two examples, one of a 'reflective' collision and another of a 'grazing' collision is shown. From drops of unequal size, coalescence can result in considerable mixing between the fluid from the small and the large drop. This problem is discussed and one example showed. In many cases it is necessary to account also for heat transfer along with the fluid mechanics. We show two preliminary results where we are using extensions of the method to simulate such a problem. One example shows pattern formation among many drops moving due to thermal migration, the other shows unstable evolution of a solidification front.

  4. Highway Collision Investigation Training Program. Final Report.

    ERIC Educational Resources Information Center

    Garrett, John W.

    The report was prepared for the National Highway Traffic Safety Administration (NHTSA) of the U.S. Department of Transportation. The report briefly reviews the appropriate literature, then describes the one-year program which involved planning and organization of a Highway Collision Investigation Training Program, preparing a course syllabus, and…

  5. Fan Affinity Laws from a Collision Model

    ERIC Educational Resources Information Center

    Bhattacharjee, Shayak

    2012-01-01

    The performance of a fan is usually estimated using hydrodynamical considerations. The calculations are long and involved and the results are expressed in terms of three affinity laws. In this paper we use kinetic theory to attack this problem. A hard sphere collision model is used, and subsequently a correction to account for the flow behaviour…

  6. Cell Biology: Microtubule Collisions to the Rescue.

    PubMed

    Gardner, Melissa K

    2016-12-19

    The proper regulation of microtubule lengths is fundamental to their cellular function. New work now reports that the collision of a growing microtubule end with another object, such as a microtubule, can contribute to the regulation of microtubule lengths by leaving behind damage that ultimately acts to stabilize the microtubule network.

  7. Electron-Atom Collisions in Gases

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  8. Relativistic Hydrodynamics for Heavy-Ion Collisions

    ERIC Educational Resources Information Center

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  9. Collision avoidance for CTV: Requirements and capabilities

    NASA Technical Reports Server (NTRS)

    Nosek, Thomas P.

    1991-01-01

    Cargo transfer vehicle (CTV) operations near Space Station Freedom will require positive collision avoidance maneuver (CAM) capability to preclude any change of collision, even in the event of CTV failures. The requirements for CAM are discussed, and the CAM design approach and design of the Orbiting Maneuvering Vehicle (OMV) are reviewed; this design met requirements for OMV operation near the Space Station, provided a redundant collision avoidance maneuver capability. Significant portions of the OMV CAM design should be applicable to CTV. The key features of the OMV design are summarized and related to the CTV mission design to that of OMV's. CAM is a defined sequence of events executed by the CTV to place the vehicle in a safe position relative to a target such as the Space Station. CAM can be performed through software commands to the propulsion system, or through commands pre-stored in hardware. Various techniques for triggering CAM are considered, and the risks associated with CAM enable and execution in phases are considered. OMV CAM design features both hardware and software CAM capability, with analyses conducted to assess the ability to meet the collision-free requirement during all phases of the mission.

  10. Collision avoidance for CTV: Requirements and capabilities

    NASA Astrophysics Data System (ADS)

    Nosek, Thomas P.

    Cargo transfer vehicle (CTV) operations near Space Station Freedom will require positive collision avoidance maneuver (CAM) capability to preclude any change of collision, even in the event of CTV failures. The requirements for CAM are discussed, and the CAM design approach and design of the Orbiting Maneuvering Vehicle (OMV) are reviewed; this design met requirements for OMV operation near the Space Station, provided a redundant collision avoidance maneuver capability. Significant portions of the OMV CAM design should be applicable to CTV. The key features of the OMV design are summarized and related to the CTV mission design to that of OMV's. CAM is a defined sequence of events executed by the CTV to place the vehicle in a safe position relative to a target such as the Space Station. CAM can be performed through software commands to the propulsion system, or through commands pre-stored in hardware. Various techniques for triggering CAM are considered, and the risks associated with CAM enable and execution in phases are considered. OMV CAM design features both hardware and software CAM capability, with analyses conducted to assess the ability to meet the collision-free requirement during all phases of the mission.

  11. Conservative discretization of the Landau collision integral

    DOE PAGES

    Hirvijoki, E.; Adams, M. F.

    2017-03-28

    Here we describe a density, momentum-, and energy-conserving discretization of the nonlinear Landau collision integral. The method is suitable for both the finite-element and discontinuous Galerkin methods and does not require structured meshes. The conservation laws for the discretization are proven algebraically and demonstrated numerically for an axially symmetric nonlinear relaxation problem using a finite-element implementation.

  12. The bouncing threshold in silica nanograin collisions.

    PubMed

    Nietiadi, Maureen L; Umstätter, Philipp; Tjong, Tiffany; Rosandi, Yudi; Millán, Emmanuel N; Bringa, Eduardo M; Urbassek, Herbert M

    2017-06-28

    Using molecular dynamics simulations, we study collisions between amorphous silica nanoparticles. Our silica model contains uncontaminated surfaces, that is, the effect of surface hydroxylation or of adsorbed water layers is excluded. For central collisions, we characterize the boundary between sticking and bouncing collisions as a function of impact velocity and particle size and quantify the coefficient of restitution. We show that the traditional Johnson-Kendall-Roberts (JKR) model provides a valid description of the ingoing trajectory of two grains up to the moment of maximum compression. The distance of closest approach is slightly underestimated by the JKR model, due to the appearance of plasticity in the grains, which shows up in the form of localized shear transformation zones. The JKR model strongly underestimates the contact radius and the collision duration during the outgoing trajectory, evidencing that the breaking of covalent bonds during grain separation is not well described by this model. The adhesive neck formed between the two grains finally collapses while creating narrow filaments joining the grains, which eventually tear.

  13. Fan Affinity Laws from a Collision Model

    ERIC Educational Resources Information Center

    Bhattacharjee, Shayak

    2012-01-01

    The performance of a fan is usually estimated using hydrodynamical considerations. The calculations are long and involved and the results are expressed in terms of three affinity laws. In this paper we use kinetic theory to attack this problem. A hard sphere collision model is used, and subsequently a correction to account for the flow behaviour…

  14. Chemical activation through super energy transfer collisions.

    PubMed

    Smith, Jonathan M; Nikow, Matthew; Ma, Jianqiang; Wilhelm, Michael J; Han, Yong-Chang; Sharma, Amit R; Bowman, Joel M; Dai, Hai-Lung

    2014-02-05

    Can a molecule be efficiently activated with a large amount of energy in a single collision with a fast atom? If so, this type of collision will greatly affect molecular reactivity and equilibrium in systems where abundant hot atoms exist. Conventional expectation of molecular energy transfer (ET) is that the probability decreases exponentially with the amount of energy transferred, hence the probability of what we label "super energy transfer" is negligible. We show, however, that in collisions between an atom and a molecule for which chemical reactions may occur, such as those between a translationally hot H atom and an ambient acetylene (HCCH) or sulfur dioxide, ET of chemically significant amounts of energy commences with surprisingly high efficiency through chemical complex formation. Time-resolved infrared emission observations are supported by quasi-classical trajectory calculations on a global ab initio potential energy surface. Results show that ∼10% of collisions between H atoms moving with ∼60 kcal/mol energy and HCCH result in transfer of up to 70% of this energy to activate internal degrees of freedom.

  15. Origin of the moon - The collision hypothesis

    NASA Astrophysics Data System (ADS)

    Stevenson, D. J.

    By the impact or collision hypothesis, the author means any theory that seeks to derive the Moon-forming material from the outcome of one or more collisions between the Earth and other Sun-orbiting bodies. The impacting body or bodies must be large - larger than the Moon and perhaps even larger than Mars. This definition does not assume that the formation of the Moon was necessarily a singular event. Among proponents of the collision hypothesis, there are those who think that a single event overwhelmingly dominated and those who think that a few (or even many) impact events were needed. There are even versions of the collision hypothesis that are not very different from extreme versions of one of the alternative origin scenarios of capture, fission, and binary accretion! This review proceeds by advancing 10 propositions that the author believes embody the most important issues confronting the theory. These propositions may or may not be true, but they form a framework for asking the right questions.

  16. AN AIRBORNE COLLISION-WARNING DEVICE,

    DTIC Science & Technology

    A simplified airborne collision- warning device is suggested in which each aircraft transmits its barometric altitude by radio. The likelihood of...signals into ’near’ and ’far’ categories would have to be determined by flight tests, it is felt that the low cost and early availability of the system justifies its consideration. (Author)

  17. Rapidity Correlation Structure in Nuclear Collisions

    NASA Astrophysics Data System (ADS)

    Zin, Christopher; Gavin, Sean; Moschelli, George

    2016-09-01

    The forces that drive the nuclear collision system towards local thermal equilibrium leave few observable traces. Heavy ion experiments report a range of features widely attributed to the hydrodynamic flow of a near-equilibrium quark gluon plasma. In particular, measurements of azimuthal anisotropy provide the most comprehensive support for the hydrodynamic description of these systems. In search of the source of this flow, we turned to smaller proton-proton, proton-nucleus and deuterium-nucleus collisions, expecting to find this effect absent. Instead, these collisions show an azimuthal anisotropy that is comparable to the larger ion-ion systems. How can we learn about the mechanisms that give rise to hydrodynamics if every available collision system exhibits flow? We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time τπ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity ν = η / sT . We formulate methods for computing these correlations using second order dissipative hydrodynamics with noise. Current data are consistent with τπ / ν 10 but targeted measurements can improve this precision. NSF PHY-1207687.

  18. Electron-Atom Collisions in Gases

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  19. Relativistic Hydrodynamics for Heavy-Ion Collisions

    ERIC Educational Resources Information Center

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  20. Collision-based mechanics of bipedal hopping.

    PubMed

    Gutmann, Anne K; Lee, David V; McGowan, Craig P

    2013-08-23

    The muscle work required to sustain steady-speed locomotion depends largely upon the mechanical energy needed to redirect the centre of mass and the degree to which this energy can be stored and returned elastically. Previous studies have found that large bipedal hoppers can elastically store and return a large fraction of the energy required to hop, whereas small bipedal hoppers can only elastically store and return a relatively small fraction. Here, we consider the extent to which large and small bipedal hoppers (tammar wallabies, approx. 7 kg, and desert kangaroo rats, approx. 0.1 kg) reduce the mechanical energy needed to redirect the centre of mass by reducing collisions. We hypothesize that kangaroo rats will reduce collisions to a greater extent than wallabies since kangaroo rats cannot elastically store and return as high a fraction of the mechanical energy of hopping as wallabies. We find that kangaroo rats use a significantly smaller collision angle than wallabies by employing ground reaction force vectors that are more vertical and center of mass velocity vectors that are more horizontal and thereby reduce their mechanical cost of transport. A collision-based approach paired with tendon morphometry may reveal this effect more generally among bipedal runners and quadrupedal trotters.

  1. Collision-based mechanics of bipedal hopping

    PubMed Central

    Gutmann, Anne K.; Lee, David V.; McGowan, Craig P.

    2013-01-01

    The muscle work required to sustain steady-speed locomotion depends largely upon the mechanical energy needed to redirect the centre of mass and the degree to which this energy can be stored and returned elastically. Previous studies have found that large bipedal hoppers can elastically store and return a large fraction of the energy required to hop, whereas small bipedal hoppers can only elastically store and return a relatively small fraction. Here, we consider the extent to which large and small bipedal hoppers (tammar wallabies, approx. 7 kg, and desert kangaroo rats, approx. 0.1 kg) reduce the mechanical energy needed to redirect the centre of mass by reducing collisions. We hypothesize that kangaroo rats will reduce collisions to a greater extent than wallabies since kangaroo rats cannot elastically store and return as high a fraction of the mechanical energy of hopping as wallabies. We find that kangaroo rats use a significantly smaller collision angle than wallabies by employing ground reaction force vectors that are more vertical and center of mass velocity vectors that are more horizontal and thereby reduce their mechanical cost of transport. A collision-based approach paired with tendon morphometry may reveal this effect more generally among bipedal runners and quadrupedal trotters. PMID:23843217

  2. (Atomic collisions in solid and plasma physics)

    SciTech Connect

    Robinson, M.T.

    1989-09-05

    The author visited the Max-Planck-Institut for Plasma Physics, Garching, FRG, to continue collaborative research activities in the area of sputtering and plasma-wall interactions. He then attended the Thirteenth International Conference on Atomic Collisions in Solids, where he presented a paper on recent research at ORNL. A few remarks about cold fusion'' are appended.

  3. Networks based on collisions among mobile agents

    NASA Astrophysics Data System (ADS)

    González, Marta C.; Lind, Pedro G.; Herrmann, Hans J.

    2006-12-01

    We investigate in detail a recent model of colliding mobile agents [M.C. González, P.G. Lind, H.J. Herrmann, Phys. Rev. Lett. 96 (2006) 088702. cond-mat/0602091], used as an alternative approach for constructing evolving networks of interactions formed by collisions governed by suitable dynamical rules. The system of mobile agents evolves towards a quasi-stationary state which is, apart from small fluctuations, well characterized by the density of the system and the residence time of the agents. The residence time defines a collision rate, and by varying this collision rate, the system percolates at a critical value, with the emergence of a giant cluster whose critical exponents are the ones of two-dimensional percolation. Further, the degree and clustering coefficient distributions, and the average path length, show that the network associated with such a system presents non-trivial features which, depending on the collision rules, enables one not only to recover the main properties of standard networks, such as exponential, random and scale-free networks, but also to obtain other topological structures. To illustrate, we show a specific example where the obtained structure has topological features which characterize the structure and evolution of social networks accurately in different contexts, ranging from networks of acquaintances to networks of sexual contacts.

  4. Primordial Particles; Collisions of Inelastic Particles

    NASA Astrophysics Data System (ADS)

    Sagi, George

    2011-03-01

    Three-dimensional matter is not defined by Euclidian or Cartesian geometries. Newton's and Einstein's laws are related to the motions of elastic masses. The study of collisions of inelastic particles opens up new vistas in physics. The present article reveals how such particles create clusters composed of various numbers of particles. The Probability of each formation, duplets, triplets, etc. can be calculated. The particles are held together by a binding force, and depending upon the angles of collisions they may also rotate around their center of geometry. Because of these unique properties such inelastic particles are referred to as primordial particles, Pp. When a given density of Pp per cubic space is given, then random collisions create a field. The calculation of the properties of such primordial field is very complex and beyond the present study. However, the angles of collisions are infinite in principle, but the probabilities of various cluster sizes are quantum dependent. Consequently, field calculations will require new complex mathematical methods to be discovered yet.

  5. On wounded constituents in nuclear collisions

    NASA Astrophysics Data System (ADS)

    Bożek, Piotr; Broniowski, Wojciech; Rybczyński, Maciej

    2017-04-01

    In this talk we summarize the main results of our recent paper [1], where we explore predictions of the wounded quark model for particle production and the properties of the initial state formed in ultra-relativistic collisions of atomic nuclei. Presented by M. Rybczyński

  6. QCD in hadron-hadron collisions

    SciTech Connect

    Albrow, M.

    1997-03-01

    Quantum Chromodynamics provides a good description of many aspects of high energy hadron-hadron collisions, and this will be described, along with some aspects that are not yet understood in QCD. Topics include high E{sub T} jet production, direct photon, W, Z and heavy flavor production, rapidity gaps and hard diffraction.

  7. Strangeness production in AA and pp collisions

    NASA Astrophysics Data System (ADS)

    Castorina, Paolo; Satz, Helmut

    2016-07-01

    Boost-invariant hadron production in high-energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions ( pp , e^+e^- below LHC energies. In contrast, the space-time superposition of individual collisions in high-energy heavy-ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we determine the collision energies needed for that; we also estimate when pp collisions reach comparable hadronization volumes and thus determine when strangeness suppression should disappear there as well.

  8. Collision of Bose Condensate Dark Matter structures

    SciTech Connect

    Guzman, F. S.

    2008-12-04

    The status of the scalar field or Bose condensate dark matter model is presented. Results about the solitonic behavior in collision of structures is presented as a possible explanation to the recent-possibly-solitonic behavior in the bullet cluster merger. Some estimates about the possibility to simulate the bullet cluster under the Bose Condensate dark matter model are indicated.

  9. A Liquid Sodium α ω Dynamo Experiment

    NASA Astrophysics Data System (ADS)

    Colgate, Stirling; Beckley, Howard; Li, Hui; Sonnenfield, Richard; Westpfahl, Dave; Bentley, Ian; Ginanni, Rocky; McKinnly, Travis; Pariev, Valadimir

    2004-11-01

    A Liquid Sodium α ω Dynamo Experiment; Stirling Colgate, Howard Beckley, Hui Li, Richard Sonnenfeld, Dave Westpfahl, Ian Bentley, Rocky Ginanni, Travis Mckinnly, and Valadimir Pariev, LANL, NMIMT, & Univ. of Rochester. A liquid sodium α ω dynamo experiment has been constructed at NMIMT to simulate MRI, dynamo gain, and feed back in liquid sodium (r1 = 15 cm,; r2 = 30 cm,; L=30 cm,; f1 = 120 Hz,; f2 = 30 Hz ). It is designed to simulate the generation of large scale magnetic fields in massive black hole accretion disks, galaxies, and stars. The omega gain is due to the shear flow of differential rotation of Couette flow between two differentially rotating co-axial cylinders. Differential rotation in a conducting fluid twists a radial or quadrupole magnetic flux into a greatly enhanced toroidal flux. A large coherent helicity is produced by driven plumes and astrophisically by star-disk collisions, supernova explosions, or large scale plume convection respectively. We have rotated the apparatus with water and hot oil and demonstrated stable Couette flow with only Ekman-flow-induced torque. We will report on the ω gain with liquid sodium. This Work has been supported by NMIMT, EMRTC, NSF, & LDRD of LANL.

  10. Modeling collisions in circumstellar debris disks

    NASA Astrophysics Data System (ADS)

    Nesvold, Erika

    2015-10-01

    Observations of resolved debris disks show a spectacular variety of features and asymmetries, including inner cavities and gaps, inclined secondary disks or warps, and eccentric, sharp-edged rings. Embedded exoplanets could create many of these features via gravitational perturbations, which sculpt the disk directly and by generating planetesimal collisions. In this thesis, I present the Superparticle Model/Algorithm for Collisions in Kuiper belts and debris disks (SMACK), a new method for simultaneously modeling, in 3-D, the collisional and dynamical evolution of planetesimals in a debris disk with planets. SMACK can simulate azimuthal asymmetries and how these asymmetries evolve over time. I show that SMACK is stable to numerical viscosity and numerical heating over 107 yr, and that it can reproduce analytic models of disk evolution. As an example of the algorithm's capabilities, I use SMACK to model the evolution of a debris ring containing a planet on an eccentric orbit and demonstrate that differential precession creates a spiral structure as the ring evolves, but collisions subsequently break up the spiral, leaving a narrower eccentric ring. To demonstrate SMACK's utility in studying debris disk physics, I apply SMACK to simulate a planet on a circular orbit near a ring of planetesimals that are experiencing destructive collisions. Previous simulations of a planet opening a gap in a collisionless debris disk have found that the width of the gap scales as the planet mass to the 2/7th power (alpha = 2/7). I find that gap sizes in a collisional disk still obey a power law scaling with planet mass, but that the index alpha of the power law depends on the age of the system t relative to the collisional timescale t coll of the disk by alpha = 0.32(t/ tcoll)-0.04, with inferred planet masses up to five times smaller than those predicted by the classical gap law. The increased gap sizes likely stem from the interaction between collisions and the mean motion

  11. Ionic Liquids Database- (ILThermo)

    National Institute of Standards and Technology Data Gateway

    SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

  12. On the quantum Landau collision operator and electron collisions in dense plasmas

    SciTech Connect

    Daligault, Jérôme

    2016-03-15

    The quantum Landau collision operator, which extends the widely used Landau/Fokker-Planck collision operator to include quantum statistical effects, is discussed. The quantum extension can serve as a reference model for including electron collisions in non-equilibrium dense plasmas, in which the quantum nature of electrons cannot be neglected. In this paper, the properties of the Landau collision operator that have been useful in traditional plasma kinetic theory and plasma transport theory are extended to the quantum case. We outline basic properties in connection with the conservation laws, the H-theorem, and the global and local equilibrium distributions. We discuss the Fokker-Planck form of the operator in terms of three potentials that extend the usual two Rosenbluth potentials. We establish practical closed-form expressions for these potentials under local thermal equilibrium conditions in terms of Fermi-Dirac and Bose-Einstein integrals. We study the properties of linearized quantum Landau operator, and extend two popular approximations used in plasma physics to include collisions in kinetic simulations. We apply the quantum Landau operator to the classic test-particle problem to illustrate the physical effects embodied in the quantum extension. We present useful closed-form expressions for the electron-ion momentum and energy transfer rates. Throughout the paper, similarities and differences between the quantum and classical Landau collision operators are emphasized.

  13. Viscosity of a classical gas: The rare-collision versus the frequent-collision regime

    NASA Astrophysics Data System (ADS)

    Magner, A. G.; Gorenstein, M. I.; Grygoriev, U. V.

    2017-05-01

    The shear viscosity η for a dilute classical gas of hard-sphere particles is calculated by solving the Boltzmann kinetic equation in terms of the weakly absorbed plane waves. For the rare-collision regime, the viscosity η as a function of the equilibrium gas parameters—temperature T , particle number density n , particle mass m , and hard-core particle diameter d —is quite different from that of the frequent-collision regime, e.g., from the well-known result of Chapman and Enskog. An important property of the rare-collision regime is the dependence of η on the external ("nonequilibrium") parameter ω , frequency of the sound plane wave, that is absent in the frequent-collision regime at leading order of the corresponding perturbation expansion. A transition from the frequent to the rare-collision regime takes place when the dimensionless parameter n d2(T/m ) 1 /2ω-1 goes to zero. The scaled absorption coefficient for sound waves calculated in the rare and frequent-collision regimes is found to be in qualitative agreement with the experimental data.

  14. Atom trap loss, elastic collisions, and technology

    NASA Astrophysics Data System (ADS)

    Booth, James

    2012-10-01

    The study of collisions and scattering has been one of the most productive approaches for modern physics, illuminating the fundamental structure of crystals, surfaces, atoms, and sub-atomic particles. In the field of cold atoms, this is no less true: studies of cold atom collisions were essential to the production of quantum degenerate matter, the formation of cold molecules, and so on. Over the past few years it has been my delight to investigate elastic collisions between cold atoms trapped in either a magneto-optical trap (MOT) or a magnetic trap with hot, background gas in the vacuum environment through the measurement of the loss of atoms from the trap. Motivated by the goal of creating cold atom-based technology, we are deciphering what the trapped atoms are communicating about their environment through the observed loss rate. These measurements have the advantages of being straightforward to implement and they provide information about the underlying, fundamental inter-atomic processes. In this talk I will present some of our recent work, including the observation of the trap depth dependence on loss rate for argon-rubidium collisions. The data follow the computed loss rate curve based on the long-range Van der Waals interaction between the two species. The implications of these findings are exciting: trap depths can be determined from the trap loss measurement under controlled background density conditions; observation of trap loss rate in comparison to models for elastic, inelastic, and chemical processes can lead to improved understanding and characterization of these fundamental interactions; finally the marriage of cold atoms with collision modeling offers the promise of creating a novel pressure sensor and pressure standard for the high and ultra-high vacuum regime.

  15. Molecular Dissociation Induced by Electron Collisions

    NASA Astrophysics Data System (ADS)

    Wolf, Andreas

    2009-05-01

    Free electrons can efficiently break molecules or molecular ions in low-energy collisions by the processes of dissociative recombination or attachment. These processes make slow electrons efficient chemical agents in many environments. For dissociative recombination, in particular, studies of the underlying reaction paths and mechanisms have become possible on a uniquely elementary level in recent years both for theory and experiment. On the experimental side, collisions can be prepared at resolved collision energies down to the meV (10 Kelvin) level, increasingly gaining control also over the initial molecular quantum level, and individual events are detected and kinematically analyzed by fast-beam coincidence fragment imaging. Experiments are reported from the ion cooler ring TSR in Heidelberg. Stored beams of molecular ions cooled in their external and internal degrees of freedom are collinearly merged with intense and cold electron beams from cryogenic GaAs photocathodes, recently shown to yield fast cooling of the center-of-mass motion also for heavy and correspondingly slow molecular ion beams. To reconstruct the molecular fragmentation events multiparticle imaging can now be used systematically with collision energies set a wide range, especially aiming at specific electron capture resonances. Thus, for CF^+ it is found that the electronic state of the C fragment (^3P or ^1D) switches resonantly when the collision energy is changed by only a small fraction. As a new powerful tool, an energy-sensitive multi-strip surface-barrier detector (EMU) has been set up to measure with near-unity efficiency the masses of all fragments together with their hit positions in high-multiplicity events. Among many uses, this device allows internal molecular excitations to be derived for individual chemical channels in polyatomic fragmentation. New results will be presented in particular on the breakup of the hydronium ion (D3O^+).

  16. Collision Tumor Composed of Meningioma and Cavernoma

    PubMed Central

    Weigel, Jens; Neher, Markus; Schrey, Michael; Wünsch, Peter H.; Steiner, Hans-Herbert

    2017-01-01

    A true collision tumor is a rare entity composed of two histologically distinct neoplasms coinciding in the same organ. This paper reports a unique case of cerebral collision tumor consisting of two benign components. On the first hand, meningioma which is usually a benign lesion arising from the meningothelial cell in the arachnoidal membrane. On the other, cerebral cavernoma which is a well-circumscribed, benign vascular hamartoma within the brain. To our knowledge, there is no previously documented case of cerebral collision tumor consisting of two benign components. A 56-year-old Caucasian male suffered in 2002 from an atypical meningioma WHO II° located in the left lateral ventricle. Three years after the tumor extirpation, the patient suffered from a hematoma in the fourth ventricle due to a recurrently haemorrhaged cavernoma. In 2008, a recurrence of the tumor in the left lateral ventricle was discovered. Additionally, another tumor located in the quadrigeminal lamina was detected. After surgical resection of the tumor in the left lateral ventricle, the pathological examination confirmed the diagnosis of a collision tumor consisting of components of a meningioma WHO II° and a cavernoma. Postoperatively, no adjuvant treatment was needed and no tumor recurrence is discovered up to the present. A possible explanation for the collision of those two different tumors may be migration of tumor cells mediated by the cerebrospinal fluid. After 5-years of follow-up, there is no sign of any tumor recurrence; therefore, surgical tumor removal without adjuvant therapy seems to be the treatment of choice. PMID:28061500

  17. Simulations of collision of ice particles

    NASA Astrophysics Data System (ADS)

    Zamankhan, Piroz

    2010-06-01

    The objective of this paper is to develop a realistic model for ice-structure interaction. To this end, the experiments made by Bridges et al. [Bridges FG, Hatzes A, Liu DNC. Structure, stability and evolution of Saturn's rings. Nature 1984;309:333-5] in order to measure the coefficient of restitution for ice particles are thoroughly analyzed. One particularly troublesome aspect of the aforementioned experiments is fracture of the ice particles during a collision. In the present effort, the collisional properties of the ice particles are investigated using a Finite Element approach. It is found that a major challenge in modeling collision of the ice balls is the prediction of the onset of fracture and crack propagation in them. In simulations of a block of ice collision to a structure, it is crucial that fracture is determined correctly, as it will influence the collisional properties of the ice particles. The results of the simulation, considering fracture criterion implemented into the Finite Element Model [Zamankhan P, Bordbar M-H. Complex flow dynamics in dense granular flows. Part I: experimentation. J Appl Mech (T-ASME) 2006;73:648-57; Zamankhan P, Huang J. Complex flow dynamics in dense granular flows. Part II: simulations. J Appl Mech (T-ASME) 2007;74:691-702] together with a material model for the ice, imply that most of the kinetic energy dissipation occurs as a result of fracturing at the contact surface of the ice particles. The results obtained in the present study suggest that constitutive models such as those proposed by Brilliantov et al. [Brilliantov NV, Spahn F, Hertzsch JM, Poschel T. Model for collisions in granular gases. Phys Rev E;1996;53:5382-92] for collisions of ice particles are highly questionable.

  18. Collision tumors: pancreatic adenocarcinoma and mantle cell lymphoma.

    PubMed

    Dasanu, Constantin A; Shimanovsky, Alexei; Rotundo, Edyta K; Posteraro, Anthony F; Cooper, Dennis L; Atienza, Jonessa A

    2013-07-10

    Collision tumors are very rare entities composed of two or more distinct tumor components, each separated by normal tissue. Perhaps due to technical advances in the last decade, the incidence of collision tumors has been on the rise. To the best of our knowledge, collision tumors featuring mantle cell lymphoma and pancreatic adenocarcinoma have not been previously described in the scientific literature. For the first time, we describe herein the clinical course of a collision tumor between pancreatic adenocarcinoma and mantle cell lymphoma. We hypothesize several aspects in the pathogenesis of a such event and review the existing literature on collision tumors.

  19. Total Probability of Collision as a Metric for Finite Conjunction Assessment and Collision Risk Management

    NASA Astrophysics Data System (ADS)

    Frigm, R.; Johnson, L.

    The Probability of Collision (Pc) has become a universal metric and statement of on-orbit collision risk. Although several flavors of the computation exist and are well-documented in the literature, the basic calculation requires the same input: estimates for the position, position uncertainty, and sizes of the two objects involved. The Pc is used operationally to make decisions on whether a given conjunction poses significant collision risk to the primary object (or space asset of concern). It is also used to determine necessity and degree of mitigative action (typically in the form of an orbital maneuver) to be performed. The predicted post-maneuver Pc also informs the maneuver planning process into regarding the timing, direction, and magnitude of the maneuver needed to mitigate the collision risk. Although the data sources, techniques, decision calculus, and workflows vary for different agencies and organizations, they all have a common thread. The standard conjunction assessment and collision risk concept of operations (CONOPS) predicts conjunctions, assesses the collision risk (typically, via the Pc), and plans and executes avoidance activities for conjunctions as a discrete events. As the space debris environment continues to increase and improvements are made to remote sensing capabilities and sensitivities to detect, track, and predict smaller debris objects, the number of conjunctions will in turn continue to increase. The expected order-of-magnitude increase in the number of predicted conjunctions will challenge the paradigm of treating each conjunction as a discrete event. The challenge will not be limited to workload issues, such as manpower and computing performance, but also the ability for satellite owner/operators to successfully execute their mission while also managing on-orbit collision risk. Executing a propulsive maneuver occasionally can easily be absorbed into the mission planning and operations tempo; whereas, continuously planning evasive

  20. How Tiny Collisions Shape Mercury

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-07-01

    If space rocks are unpleasant to encounter, space dust isnt much better. Mercurys cratered surface tells of billions of years of meteoroid impacts but its thin atmosphere is what reveals its collisional history with smaller impactors. Now new research is providing a better understanding of what were seeing.Micrometeoroids Ho!The inner solar system is bombarded by micrometeoroids, tiny particles of dust (on the scale of a tenth of a millimeter) emitted by asteroids and comets as they make their closest approach to the Sun. This dust doesnt penetrateEarths layers of atmosphere, but the innermost planet of our solar system, Mercury, doesnt have this convenient cushioning.Just as Mercury is affected by the impacts of large meteoroids, its also shaped by the many smaller-scale impacts it experiences. These tiny collisions are thought to vaporize atoms and molecules from the planets surface, which quickly dissociate. This process adds metals to Mercurys exosphere, the planets extremely tenuous atmosphere.Modeling PopulationsDistribution of the directions from which meteoroids originate before impacting Mercurys surface, as averaged over its entire orbit. Local time of 12 hr corresponds to the Sun-facing side. A significant asymmetry is seen between the dawn (6 hrs) and dusk (18 hrs) rates. [Pokorn et al. 2017]The metal distribution in the exosphere provides a way for us to measure the effect of micrometeoroid impacts on Mercury but this only works if we have accurate models of the process. A team of scientists led by Petr Pokorn (The Catholic University of America and NASA Goddard SFC) has now worked to improve our picture of micrometeoroid impact vaporization on Mercury.Pokorn and collaborators argue that two meteoroid populations Jupiter-family comets (short-period) and Halley-type comets (long-period) contribute the dust for the majority of micrometeoroid impacts on Mercury. The authors model the dynamics and evolution of these two populations, reproducing the

  1. Experimental Investigation on Liquid Behaviors in Nanopores

    NASA Astrophysics Data System (ADS)

    Lu, Weiyi

    Nanoporous materials are involved in many industrial processes such as catalysis, filtration, chromatography, etc. Recently, they are applied to absorb or capture the energy associated with blast, collision, and impact attacks. In such applications, the nanoporous materials are immersed in liquids or gels. The inner surfaces of nanopores are usually modified to increase the degree of hydrophobicity. When an external pressure is applied on the system, the liquid phase can be compressed into the nanoporous space. The liquid infiltration behavior in the nanopores becomes significantly different from that of untreated material. The effective interfacial tension and viscosity of the confined liquid are investigated. While the simple superposition principle can be employed for the analysis of interfacial tension, in a nanopore the effective liquid viscosity is no longer a material constant. It is highly dependent on the pore size and the loading rate, much smaller than its bulk counterpart. In addition, the influence of electrolyte concentration as well as its dependence on temperature are analyzed in detail. As the electrolyte concentration varies, the effective interfacial tension changes rapidly. The testing data show that, the pressure-induced infiltration behavior is not only determined by the cations, but also highly dependent on the anion species. The transport behaviors of solvated ions in nanopores can be field responsive, providing a novel method to develop interactive protection systems. As an external electric field is applied, the observed change in effective solid-liquid interfacial tension is contradictory to the prediction of classic electrochemistry theory. To simplify the materials handling, a polypropylene-matrix composite material is produced. When the temperature is relatively low, the matrix dominates the system behavior. When the temperature is relatively high, with a sufficiently large external pressure the polymer phase can be intruded into the

  2. Geometrical methods in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Taliotis, Anastasios

    Currently there exists no known way to construct the Stress-Energy tensor (Tmunu) of the medium produced in heavy ion collisions at strong coupling from purely theoretical grounds. In this work, some steps are taken in that direction. In particular, the evolution of Tmunu at strong coupling and at high energies is being studied for early proper times (tau). This is achieved in the context of the AdS/CFT duality by constructing the evolution of the dual geometry in an AdS5 background. We consider high energy collisions of two shock waves in AdS5 as a model of ultra-relativistic nucleus-nucleus collisions in the boundary theory. We first calculate the graviton field produced in the collisions in the LO, NLO and NNLO approximations, corresponding to two, three and four-graviton exchanges with the shock waves. We use this model to study Tmunu and in particular the energy density of the strongly-coupled matter created immediately after the collision because as we argue, the expansion of the energy density (epsilon) in the powers of proper time tau squared corresponds on the gravity side to a perturbative expansion of the metric in graviton exchanges. We point out that shock waves corresponding to physical energy-momentum tensors of the nuclei is likely to completely stop after the collision; on the field theory side, this corresponds to complete nuclear stopping due to strong coupling effects, likely leading to Landau hydrodynamics. This motivates a more detailed investigation. For this reason we consider the asymmetric limit where the energy density in one shock wave is much higher than in the other one. In the boundary theory this setup corresponds to proton-nucleus collisions. Employing the eikonal approximation we find the exact high energy analytic solution for the metric in AdS5 for the asymmetric collision of two delta-function shock waves. The solution resums all-order graviton exchanges with the nucleus-shock wave and a single-graviton exchange with the proton

  3. Final Report for Project ``Theory of ultra-relativistic heavy-ion collisions''

    SciTech Connect

    Ulrich W. Heinz

    2012-11-09

    In the course of this project the Ohio State University group led by the PI, Professor Ulrich Heinz, developed a comprehensive theoretical picture of the dynamical evolution of ultra-relativistic heavy-ion collisions and of the numerous experimental observables that can be used to diagnose the evolving and short-lived hot and dense fireball created in such collisions. Starting from a qualitative understanding of the main features based on earlier research during the last decade of the twentieth century on collisions at lower energies, the group exploited newly developed theoretical tools and the stream of new high-quality data from the Relativistic Heavy Ion Collider at Brookhaven National Laboratory (which started operations in the summer of the year 2000) to arrive at an increasingly quantitative description of the experimentally observed phenomena. Work done at Ohio State University (OSU) was instrumental in the discovery during the years 2001-2003 that quark-gluon plasma (QGP) created in nuclear collisions at RHIC behaves like an almost perfect liquid with minimal viscosity. The tool of relativistic fluid dynamics for viscous liquids developed at OSU in the years 2005-2007 opened the possibility to quantitatively determine the value of the QGP viscosity empirically from experimental measurements of the collective flow patterns established in the collisions. A first quantitative extraction of the QGP shear viscosity, with controlled theoretical uncertainty estimates, was achieved during the last year of this project in 2010. OSU has paved the way for a transition of the field of relativistic heavy-ion physics from a qualitative discovery stage to a new stage of quantitative precision in the description of quark-gluon plasma properties. To gain confidence in the precision of our theoretical understanding of quark-gluon plasma dynamics, one must test it on a large set of experimentally measured observables. This achievement report demonstrates that we have, at

  4. Exotic hadrons from heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Cho, Sungtae; Hyodo, Tetsuo; Jido, Daisuke; Ko, Che Ming; Lee, Su Houng; Maeda, Saori; Miyahara, Kenta; Morita, Kenji; Nielsen, Marina; Ohnishi, Akira; Sekihara, Takayasu; Song, Taesoo; Yasui, Shigehiro; Yazaki, Koichi

    2017-07-01

    High energy heavy ion collisions are excellent ways for producing heavy hadrons and composite particles, including the light (anti)nuclei. With upgraded detectors at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), it has become possible to measure hadrons beyond their ground states. Therefore, heavy ion collisions provide a new method for studying exotic hadrons that are either molecular states made of various hadrons or compact system consisting of multiquarks. Because their structures are related to the fundamental properties of Quantum Chromodynamics (QCD), studying exotic hadrons is currently one of the most active areas of research in hadron physics. Experiments carried out at various accelerator facilities have indicated that some exotic hadrons may have already been produced. The present review is a summary of the current understanding of a selected set of exotic particle candidates that can be potentially measured in heavy ion collisions. It also includes discussions on the production of resonances, exotics and hadronic molecular states in these collisions based on the coalescence model and the statistical model. A more detailed discussion is given on the results from these models, leading to the conclusion that the yield of a hadron that is a compact multiquark state is typically an order of magnitude smaller than if it is an excited hadronic state with normal quark numbers or a loosely bound hadronic molecule. Attention is also given to some of the proposed heavy exotic hadrons that could be produced with sufficient abundance in heavy ion collisions because of the significant numbers of charm and bottom quarks that are produced at RHIC and even larger numbers at LHC, making it possible to study them in these experiments. Further included in the discussion are the general formalism for the coalescence model that involves resonance particles and its implication on the present estimated yield for resonance production. Finally

  5. Measurements of Correlation-Enhanced Collision Rates

    NASA Astrophysics Data System (ADS)

    Driscoll, C. Fred

    2009-11-01

    This talk presents the first detailed experimental measurements of the Salpeter collisional enhancement factor g ( γ) in strongly correlated plasmas. This factor is predicted to enhance the nuclear reaction rate in dense strongly-correlated plasmas, such as in giant planet interiors, brown dwarfs and degenerate stars;footnotetextE.E. Salpeter and H.M. Van Horn, Astrophys. J. 155, 183 (1969). and recent theory establishes that it also applies to the perpendicular-to-parallel collisions in magnetized plasmas described here.footnotetextD.H.E. Dubin, Phys. Rev. Lett. 94, 025002 (2005). The enhancement is caused by plasma screening of the repulsive Coulomb potential between charges, allowing closer collisions for a given particle energy. The enhancement factor is predicted to be large when the plasma correlation parameter γ≡e^2 /aT is larger than unity, scaling as g ( γ) ˜e^γ. The perp-to-parallel collision rate is then ν|= n v b^2 ,( κ ) ,( γ), where I ( κ ) decreases precipitously below ( 8 √π / 15 ) λ in the highly magnetized regime of κ ≡√2 ,/ rc1. Our measurementsfootnotetextF. Anderegg et al., Phys. Rev. Lett. 102, 185001 (2009); F. Anderegg et al., Phys. Plasmas 16, 055705 (2009). of ν| in Mg^+ pure ion plasmas are consistent with the predicted Salpeter correlation enhancement, with the comparison limited mainly by systematic spatial variations in the plasma temperature. The plasma temperatures are controlled over the range 4 x10-6 < T < 1eV, with the outer radii being up to 2x hotter. Bulk-averaged collision rates of 1 < ν|< 2 x10^4 sec-1 are measured by 2 techniques: for slow collisions, T| is heated or cooled, and the subsequent relaxation is directly observed; for rapid collisions, sinusoidal modulation of the plasma length at frequency fmod gives maximal heating when fmod = ν|/ 2 πc (γ), where c ( γ) is the specific heat. Two densities are used, 2.0 and 0.12 x10^7 cm-3; the lower density has ˜2.5 x less correlation at any

  6. Ion mobility derived collision cross sections to support metabolomics applications.

    PubMed

    Paglia, Giuseppe; Williams, Jonathan P; Menikarachchi, Lochana; Thompson, J Will; Tyldesley-Worster, Richard; Halldórsson, Skarphédinn; Rolfsson, Ottar; Moseley, Arthur; Grant, David; Langridge, James; Palsson, Bernhard O; Astarita, Giuseppe

    2014-04-15

    Metabolomics is a rapidly evolving analytical approach in life and health sciences. The structural elucidation of the metabolites of interest remains a major analytical challenge in the metabolomics workflow. Here, we investigate the use of ion mobility as a tool to aid metabolite identification. Ion mobility allows for the measurement of the rotationally averaged collision cross-section (CCS), which gives information about the ionic shape of a molecule in the gas phase. We measured the CCSs of 125 common metabolites using traveling-wave ion mobility-mass spectrometry (TW-IM-MS). CCS measurements were highly reproducible on instruments located in three independent laboratories (RSD < 5% for 99%). We also determined the reproducibility of CCS measurements in various biological matrixes including urine, plasma, platelets, and red blood cells using ultra performance liquid chromatography (UPLC) coupled with TW-IM-MS. The mean RSD was < 2% for 97% of the CCS values, compared to 80% of retention times. Finally, as proof of concept, we used UPLC-TW-IM-MS to compare the cellular metabolome of epithelial and mesenchymal cells, an in vitro model used to study cancer development. Experimentally determined and computationally derived CCS values were used as orthogonal analytical parameters in combination with retention time and accurate mass information to confirm the identity of key metabolites potentially involved in cancer. Thus, our results indicate that adding CCS data to searchable databases and to routine metabolomics workflows will increase the identification confidence compared to traditional analytical approaches.

  7. Collision lifetimes of polyatomic molecules at low temperatures: Benzene–benzene vs benzene–rare gas atom collisions

    SciTech Connect

    Cui, Jie; Krems, Roman V.; Li, Zhiying

    2014-10-28

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom–molecule interaction. We then compare the results of the atom–benzene calculations with those for benzene–benzene collisions. The comparison illustrates that the mean lifetimes of the benzene–benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene–benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene.

  8. Collision lifetimes of polyatomic molecules at low temperatures: Benzene-benzene vs benzene-rare gas atom collisions

    NASA Astrophysics Data System (ADS)

    Cui, Jie; Li, Zhiying; Krems, Roman V.

    2014-10-01

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom-molecule interaction. We then compare the results of the atom-benzene calculations with those for benzene-benzene collisions. The comparison illustrates that the mean lifetimes of the benzene-benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene-benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene.

  9. Collision lifetimes of polyatomic molecules at low temperatures: benzene-benzene vs benzene-rare gas atom collisions.

    PubMed

    Cui, Jie; Li, Zhiying; Krems, Roman V

    2014-10-28

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom-molecule interaction. We then compare the results of the atom-benzene calculations with those for benzene-benzene collisions. The comparison illustrates that the mean lifetimes of the benzene-benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene-benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene.

  10. Structural correlations and cooperative dynamics in supercooled liquids.

    PubMed

    Singh, Murari; Agarwal, Manish; Dhabal, Debdas; Chakravarty, Charusita

    2012-07-14

    The relationships between diffusivity and the excess, pair and residual multiparticle contributions to the entropy are examined for Lennard-Jones liquids and binary glassformers, in the context of approximate inverse power law mappings of simple liquids. In the dense liquid where diffusivities are controlled by collisions and cage relaxations, Rosenfeld-type excess entropy scaling of diffusivities is found to hold for both crystallizing as well as vitrifying liquids. The crucial differences between the two categories of liquids emerge only when local cooperative effects in the dynamics result in significant caging effects in the time-dependent behaviour of the single-particle mean square displacement. In the case of glassformers, onset of such local cooperativity coincides with onset of deviations from Rosenfeld-type excess entropy scaling of diffusivities and increasing spatiotemporal heterogeneity. In contrast, for two- and three-dimensional liquids with a propensity to crystallise, the onset of local cooperative dynamics is sufficient to trigger crystallization provided that the liquid is sufficiently supercooled that the free energy barrier to nucleation of the solid phase is negligible. The state points corresponding to onset of transient caging effects can be associated with typical values, within reasonable bounds, of the excess, pair, and residual multiparticle entropy as a consequence of the isomorph-invariant character of the excess entropy, diffusivity and related static and dynamic correlation functions.

  11. Coulomb-influenced collisions in aerosols and dusty plasmas

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Ranganathan; Hogan, Christopher J., Jr.

    2012-02-01

    In aerosol and dusty plasma systems, the behavior of suspended particles (grains) is often strongly influenced by collisions occurring between ions and particles, as well as between particles themselves. In determining the collision kernel or collision rate coefficient for such charged entities, complications arise in that the collision process can be completely described neither by continuum transport mechanics nor by free molecular (ballistic) mechanics; that is, collisions are transition regime processes. Further, both the thermal energy and the potential energy between colliding entities can strongly influence the collision rate and must be considered. Flux-matching theory, originally developed by Fuchs, is frequently applied for calculation of collision rate coefficients under these circumstances. However, recent work suggests that crucial assumptions in flux-matching theory are not appropriate to describe transition regime collisions in the presence of potential interactions. Here, we combine dimensional analysis and mean first passage time calculations to infer the collision kernel between dilute charged entities suspended in a light background gas at thermal equilibrium. The motion of colliding entities is described by a Langevin equation, and Coulombic interactions are considered. It is found that the dimensionless collision kernel for these conditions, H, is a function of the diffusive Knudsen number, KnD (in contrast to the traditional Knudsen number), and the potential energy to thermal energy ratio, ΨE. For small and large KnD, it is found that the dimensionless collision kernels inferred from mean first passage time calculations collapse to the appropriate continuum and free molecular limiting forms, respectively. Further, for repulsive collisions (ΨE negative) or attractive collisions with ΨE<0.5, calculated results are in excellent agreement with flux-matching theory predictions, and the dimensionless collision kernel can be determined

  12. Fluid dynamical description of relativistic nuclear collisions

    NASA Technical Reports Server (NTRS)

    Nix, J. R.; Strottman, D.

    1982-01-01

    On the basis of both a conventional relativistic nuclear fluid dynamic model and a two fluid generalization that takes into account the interpenetration of the target and projectile upon contact, collisions between heavy nuclei moving at relativistic speeds are calculated. This is done by solving the relevant equations of motion numerically in three spatial dimensions by use of particle in cell finite difference computing techniques. The effect of incorporating a density isomer, or quasistable state, in the nuclear equation of state at three times normal nuclear density, and the effect of doubling the nuclear compressibility coefficient are studied. For the reaction 20Ne + 238U at a laboratory bombarding energy per nucleon of 393 MeV, the calculated distributions in energy and angle of outgoing charged particles are compared with recent experimental data both integrated over all impact parameters and for nearly central collisions.

  13. US Coast Guard collision at sea.

    PubMed

    McCaughey, B G

    1985-01-01

    The collision between the USCGC Cuyahoga and the motor vessel Santa Cruz II resulted in psychological distress among the Coast Guard crewmen. The US Navy Special Psychiatric Rapid Intervention Team (SPRINT) was activated to provide mental health services to the Coast Guard survivors and others who had been affected by the disaster. The psychiatric records of the 18 survivors were examined and summarized, and combined with anecdotal comments made by SPRINT members. The most prominent psychological reactions among the survivors were shock, anger, sadness, and guilt. Spouses of the survivors dealt with bereavement and strove to understand their husbands' reactions. Variables identified by the SPRINT as being important to their success were communication with and support from the training center command, assurances of confidentiality to the survivors, and commencement of their work almost immediately following the collision.

  14. Collision of two rotating Hayward black holes

    NASA Astrophysics Data System (ADS)

    Gwak, Bogeun

    2017-07-01

    We investigate the spin interaction and the gravitational radiation thermally allowed in a head-on collision of two rotating Hayward black holes. The Hayward black hole is a regular black hole in a modified Einstein equation, and hence it can be an appropriate model to describe the extent to which the regularity effect in the near-horizon region affects the interaction and the radiation. If one black hole is assumed to be considerably smaller than the other, the potential of the spin interaction can be analytically obtained and is dependent on the alignment of angular momenta of the black holes. For the collision of massive black holes, the gravitational radiation is numerically obtained as the upper bound by using the laws of thermodynamics. The effect of the Hayward black hole tends to increase the radiation energy, but we can limit the effect by comparing the radiation energy with the gravitational waves GW150914 and GW151226.

  15. Munroe effect based on detonation wave collision

    NASA Astrophysics Data System (ADS)

    Miao, Yusong; Li, Xiaojie; Wang, Xiaohong; Yan, Honghao; Chen, Xiang

    2017-05-01

    Munroe effect has been more and more used in blasting engineering and most assembling energy technologies use a shaped charge device. In this paper, a new method is used to achieve detonation wave collision by detonating cord initiation system. A numerical simulation using LS-DYNA on detonation wave propagation and collision process caused by different initiation forms is implemented. Numerical results show that peak pressure by this new method can reach 2.42 times than the traditional method, and the growth of specific impulse at the explosive bottom is 49% compared to early results. Based on this numerical simulation, an experiment of explosive-determination of power be implemented, the experiment result can verify the simulation result well.

  16. Long-range consequences of interplanetary collisions

    NASA Technical Reports Server (NTRS)

    Sagan, Carl; Ostro, Steven J.

    1994-01-01

    As Comet Shoemaker-Levy 9 races toward its mid-July collision with the planet Jupiter, considerable public attention is focused on catastrophic impacts with the Earth -- in the past and in the future. In recent years calls have been made to develop technologies that could deflect any asteroid or comet on a collision course. Careful consideration must be given to the nature and time scale of the risk and to the cost-effectiveness and possible problems in the suggested solutions. Risk assessment, threat removal, and resources misuse are examined. The greatest concern is to have a poorly informed public -- exerting pressure for means to mitigate even non-existent threats. The only foreseeable solution is a combination of accurate orbit estimation, realistic threat assessment, and effective public education.

  17. Theory of Electron-Ion Collisions

    SciTech Connect

    Griffin, Donald C

    2009-10-02

    Collisions of electrons with atoms and ions play a crucial role in the modeling and diagnostics of fusion plasmas. In the edge and divertor regions of magnetically confined plasmas, data for the collisions of electrons with neutral atoms and low charge-state ions are of particular importance, while in the inner region, data on highly ionized species are needed. Since experimental measurements for these collisional processes remain very limited, data for such processes depend primarily on the results of theoretical calculations. Over the period of the present grant (January 2006 - August 2009), we have made additional improvements in our parallel scattering programs, generated data of direct fusion interest and made these data available on The Controlled Fusion Atomic Data Center Web site at Oak Ridge National Laboratory. In addition, we have employed these data to do collsional-radiative modeling studies in support of a variety of experiments with magnetically confined fusion plasmas.

  18. Path Integral Approach to Atomic Collisions

    NASA Astrophysics Data System (ADS)

    Harris, Allison

    2016-09-01

    The Path Integral technique is an alternative formulation of quantum mechanics that is based on a Lagrangian approach. In its exact form, it is completely equivalent to the Hamiltonian-based Schrödinger equation approach. Developed by Feynman in the 1940's, following inspiration from Dirac, the path integral approach has been widely used in high energy physics, quantum field theory, and statistical mechanics. However, only in limited cases has the path integral approach been applied to quantum mechanical few-body scattering. We present a theoretical and computational development of the path integral method for use in the study of atomic collisions. Preliminary results are presented for some simple systems. Ultimately, this approach will be applied to few-body ion-atom collisions. Work supported by NSF grant PHY-1505217.

  19. Active Collision Avoidance for Planetary Landers

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Hannan, Mike; Srinivasan, Karthik

    2015-01-01

    The use of automotive radar systems are being evaluated for collision avoidance in planetary landers. Our focus is to develop a low-cost, light-weight collision avoidance system that overcomes the drawbacks identified with optical-based systems. We also seek to complement the Autonomous Landing and Hazard Avoidance Technology system by providing mission planners an alternative system that can be used on low-cost, small robotic missions and in close approach. Our approach takes advantage of how electromagnetic radiation interacts with solids. As the wavelength increases, the sensitivity of the radiation to isolated solids of a specific particle size decreases. Thus, rocket exhaust-blown dust particles, which have major significance in visible wavelengths, have much less significance at radar wavelengths.

  20. Anomalons, honey, and glue in nuclear collisions

    SciTech Connect

    Gyulassy, M.

    1982-12-01

    In these lectures, selected topics in nuclear collisions in the energy range 10/sup -1/ to 10/sup 3/ GeV per nucleon are discussed. The evidence for anomalous projectile fragments with short mean free paths is presented. Theoretical speculations on novel topological nuclear excitation and on quark-nuclear complexes in connection with anomalons are discussed. Recent tests for pion field instabilities are presented. Then evidence for collective nuclear flow phenomena are reviewed. Global event analysis and cascade simulations are presented. We address the question of whether nuclear flow is like viscous honey. Finally, the criteria for the production of a quark-gluon plasma are discussed. Nuclear stopping power and longitudinal growth at high energies are considered. Results from cosmic ray data show that nuclear collision at TeV per nucleon energies are likely to product a plasma.

  1. Threat detection system for intersection collision avoidance

    NASA Astrophysics Data System (ADS)

    Jocoy, Edward H.; Pierowicz, John A.

    1998-01-01

    Calspan SRL Corporation is currently developing an on- vehicle threat detection system for intersection collision avoidance (ICA) as part of its ICA program with the National Highway Transportation Safety Administration. Crash scenarios were previously defined and an on-board radar sensor was designed. This paper describes recent efforts that include the development of a simulation of a multitarget tracker and collision avoidance algorithm used to predict system performance in a variety of target configurations in the various ICA crash scenarios. In addition, a current headway radar was mounted on the Calspan Instrumented Vehicle and in-traffic data were recorded for two limited crash scenarios. Warning functions were developed through the simulation and applied to the recorded data.

  2. A simple collision model for small bubbles

    NASA Astrophysics Data System (ADS)

    Heitkam, Sascha; Sommer, Anna-Elisabeth; Drenckhan, Wiebke; Fröhlich, Jochen

    2017-03-01

    In this work, a model for the interaction force between a small bubble and a wall or another bubble is presented. The formulation is especially designed for Lagrangian calculations of bubble or soft sphere trajectories, with or without resolution of the continuous fluid. The force only relies on position and velocity of the bubble. The model does not include any empirical parameter that would have to be calibrated. Therefore, this force model is easy to implement. The formulation of the force is explicit, which means low computational effort. The collision of a small bubble with an inclined top wall is investigated numerically and experimentally. The computational results achieved with the new collision model show good agreement with the experiment.

  3. Kinetic simulation of a plasma collision experiment

    NASA Astrophysics Data System (ADS)

    Larroche, Olivier

    1993-08-01

    The ionic Fokker-Planck code which was written for describing plasma shock wave fronts [M. Casanova et al. Phys. Rev. Lett. 67, 2143 (1991)] is applied to model the collision of two plasmas in plane geometry. Improvements brought to the code for that purpose are described. The initial phase of the experiment during which the plasmas interpenetrate is accounted for by a simple fluid model, which yields qualitative insight into the phenomena at play as well as an initial condition to start the kinetic simulation. The kinetic results obtained in the stagnation and thermalization phases are discussed with respect to a specific laser-produced plasma collision experiment, as well as to existing fluid and kinetic (``particle-in-cell'') simulations.

  4. Collision zone magmatism aids continental crustal growth

    NASA Astrophysics Data System (ADS)

    Savov, Ivan; Meliksetian, Khachatur; Ralf, Halama; Gevorg, Navasardian; Chuck, Connor; Massimo, D'Antonio; Samuele, Agostini; Osamu, Ishizuka; Sergei, Karapetian; Arkadi, Karakhanian

    2014-05-01

    The continental crust has a broadly andesitic bulk composition and is predominantly generated at convergent margins. However, estimates of the bulk composition of oceanic arcs indicate a bulk composition closer to basalt than to andesite. Hence, reworking processes that transform basaltic island arc crust into andesitic continental crust are essential[1] and explaining growth of andesitic continental crust via accretion of arc crustal fragments remains problematic. Recent studies of magmatism in the Great Tibetan Plateau[2], as site of multiple and still active continent-continent collisions, have proposed that andesitic CC is generated via amalgamation of large volumes of collision-related felsic magmas generated by melting of hydrated oceanic crust with mantle geochemical signatures. We aim to test this hypothesis by evaluating geochemical data from the volcanically and tectonically active Lesser Caucasus region (Armenia, Azerbaijan, Georgia and E. Turkey), as the only other region where active continent-continent collision takes place. We will benefit from the newly compiled volcano-tectonic database of collision-related volcanic and plutonic rocks of Armenia that is comparable in quality and detail to the one available on Tibet. Our dataset combines several detailed studies from the large Aragats shield volcano[3] and associated monogenetic volcanic fields (near the capital city of Yerevan), as well as > 500 Quaternary to Holocene volcanoes from Gegham, Vardenis and Syunik volcanic highlands (toward Armenia-Nagorno-Karabakh-Azerbaijan-Iran border). The Armenian collision-related magmatism is diverse in volume, composition, eruption style and volatile contents. Interestingly, the majority of exposed volcanics are andesitic in composition. Nearly all collision-related volcanic rocks, even the highly differentiated dacite and rhyolite ignimbrites, have elevated Sr concentrations and 87Sr/86Sr and 143Nd/144Nd ratios varying only little (average ~ 0.7043 and ~ 0

  5. Benchmark Calculations of Atomic Collision Processes

    NASA Astrophysics Data System (ADS)

    Bartschat, Klaus

    2012-02-01

    The rapid development of computational resources has resulted in enormous improvements in the accuracy of numerical calculations of atomic collision processes. This talk will concentrate on recent advances in the computational treatment of charged-particle and intense short-pulse laser interactions with atoms, ions, and small molecules. Examples include electron collisions with heavy complex targets that are of significant importance in many modelling applications in plasma and astrophysics, fundamental studies of highly correlated 4-body Coulomb processes such as simultaneous ionization with excitation, and the accurate solution of the time-dependent Schr"odinger equation in the presence of intense femto/attosecond laser fields, which paves the way for quantum dynamic imaging and coherent control.

  6. Long-range consequences of interplanetary collisions

    NASA Technical Reports Server (NTRS)

    Sagan, Carl; Ostro, Steven J.

    1994-01-01

    As Comet Shoemaker-Levy 9 races toward its mid-July collision with the planet Jupiter, considerable public attention is focused on catastrophic impacts with the Earth -- in the past and in the future. In recent years calls have been made to develop technologies that could deflect any asteroid or comet on a collision course. Careful consideration must be given to the nature and time scale of the risk and to the cost-effectiveness and possible problems in the suggested solutions. Risk assessment, threat removal, and resources misuse are examined. The greatest concern is to have a poorly informed public -- exerting pressure for means to mitigate even non-existent threats. The only foreseeable solution is a combination of accurate orbit estimation, realistic threat assessment, and effective public education.

  7. Liquid level detector

    DOEpatents

    Grasso, Albert P.

    1986-01-01

    A liquid level detector for low pressure boilers. A boiler tank, from which apor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

  8. Liquid level detector

    DOEpatents

    Grasso, A.P.

    1984-02-21

    A liquid level detector for low pressure boilers. A boiler tank, from which vapor, such as steam, normally exits via a main vent, is provided with a vertical side tube connected to the tank at the desired low liquid level. When the liquid level falls to the level of the side tube vapor escapes therethrough causing heating of a temperature sensitive device located in the side tube, which, for example, may activate a liquid supply means for adding liquid to the boiler tank. High liquid level in the boiler tank blocks entry of vapor into the side tube, allowing the temperature sensitive device to cool, for example, to ambient temperature.

  9. Effect of viscosity on droplet-droplet collision outcome: Experimental study and numerical comparison

    NASA Astrophysics Data System (ADS)

    Gotaas, Cecilie; Havelka, Pavel; Jakobsen, Hugo A.; Svendsen, Hallvard F.; Hase, Matthias; Roth, Norbert; Weigand, Bernhard

    2007-10-01

    The influence of viscosity on droplet-droplet collision behavior at ambient conditions was studied experimentally and numerically. N-decane, monoethyleneglycol (MEG), diethyleneglycol (DEG), and triethyleneglycol were used as liquid phase providing viscosities in the range from 0.9to48mPas. Collision Weber numbers ranged approximately from 10 to 420. A direct numerical simulation code, based on the volume-of-fluid concept, was used for the simulations. Experimentally, observations of two droplet streams using a modified stroboscopic technique (aliasing method) were used to investigate the whole range of impact parameters during one experimental run. The experimental method has previously been verified for the water/air system [C. Gotaas et al., Phys. Fluids 19, 102105 (2007)]. In the present work, it was tested and validated for the n-decane/air system. Measured data agree well with those published in the literature. Well-defined regions of stretching separation and coalescence were identified, while reflexive separation regions were not found by using a single sinusoidal disturbance. However, the onset of reflexive separation was identified for MEG and DEG using an amplitude modulation technique. The results show that the criteria for onset of reflexive separation for viscous fluids provided by Y. I. Jiang et al. [J. Fluid Mech. 234, 177 (1992)] are not valid. This is consistent with the results given by K. D. Willis and M. Orme [Exp. Fluids 34, 28 (2003)]. A new empirical correlation for the onset of reflexive separation for high viscosity fluids is presented. The borders between coalescing and stretching separation were shifted toward higher Weber numbers with increasing viscosity. The lack of occurrence of reflexive separation for the single sinusoidal disturbance (small droplets), as well as the stretching separation boundary shift, can be explained by dissipation of collision kinetic energy in viscous flows inside the merged droplet after collision. Results

  10. Dirac R-matrix collision strengths and effective collision strengths for transitions of Ni xvii

    NASA Astrophysics Data System (ADS)

    Hudson, C. E.; Norrington, P. H.; Ramsbottom, C. A.; Scott, M. P.

    2012-01-01

    Context. Electron impact excitation collision strengths are required for the analysis and interpretation of stellar observations. Aims: This calculation aims to provide fine structure effective collision strengths for the Ni xvii ion using a method which includes contributions from resonances. Methods: A fully relativistic R-matrix calculation has been performed using the DARC code. In the structure part of our calculation 141 fine-structure levels are employed and 37 of these are used in the scattering calculation. Results: Collision strengths have been determined for 666 fine-structure transitions arising from the 37 lowest j-levels involving configurations 3s2, 3p2, 3d2, 3s3p, 3s3d, 3p3d and 3s4s. The effective collision strengths for these transitions have been calculated for electron temperatures (Te) in the range log 10Te(K) = 4.5 - 8.0. Effective collision strengths are tabulated for transitions between the first ten fine structure levels, arising from the 3s2, 3s3p and 3p2 configurations. The remaining transitions are available at the CDS as well as via the author's website. Tables 2 and 5 are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A12

  11. Three-body collision contributions to recombination and collision-induced dissociation. 1: Cross sections

    SciTech Connect

    Pack, R.T.; Walker, R.B.; Kendrick, B.K.

    1998-04-10

    Atomic and molecular recombination and collision-induced dissociation (CID) reactions comprise two of the most fundamental types of chemical reactions. They are important in all gas phase chemistry; for example, about half of the 196 reactions identified as important in combustion chemistry are recombination or CID reactions. Many of the current chemical kinetics textbooks and kinetics papers treat atomic and molecular recombination and CID as occurring only via sequences of two-body collisions. Actually, there is considerable evidence from experiment and classical trajectory calculations for contributions by true three-body collisions to the recombination of atomic and diatomic radicals, and that evidence is reviewed. Then, an approximate quantum method treating both two-body and three-body collisions simultaneously and on equal footing is used to calculate cross sections for the reaction Ne{sub 2} + H {rightleftharpoons} Ne + Ne + H. The results provide clear quantum evidence that direct three-body collisions do contribute significantly to recombination and CID.

  12. Collision of BEC dark matter structures and comparison with the collision of ideal gas structures

    SciTech Connect

    Guzman, F. S.; Gonzalez, J. A.

    2010-12-07

    In this work we present an important feature of the Bose Einstein Condensate (BEC) dark matter model, that is, the head-on collision of BEC dark matter virialized structures. This model of dark matter is assumed to be ruled by the Schroedinger-Poisson system of equations, which is interpreted as the Gross-Pitaevskii equation with a gravitational potential sourced by the density of probability. It has been shown recently that during the collision of two structures a pattern formation in the density of probability appears. We explore the pattern formation for various initial dynamical conditions during the collision. In order to know whether or not the pattern formation is a particular property of the BEC dark matter, we compare with the collision of two structures of virialized ideal gas under similar dynamical initial conditions, which is a model more consistent with usual models of dark matter. In order to do so, we also solve Euler's equations using a smoothed particle hydrodynamics approach. We found that the collision of the ideal gas structures does not show interference patterns, which in turn implies that the pattern formation is a property of the BEC dark matter.

  13. Collisions of Planetesimals and Formation of Planets

    NASA Astrophysics Data System (ADS)

    Dvorak, Rudolf; Maindl, Thomas I.; Süli, Áron; Schäfer, Christoph M.; Speith, Roland; Burger, Christoph

    2016-01-01

    We present preliminary results of models of terrestrial planet formation using on the one hand classical numerical integration of hundreds of small bodies on CPUs and on the other hand-for comparison-the results of our GPU code with thousands of small bodies which then merge to larger ones. To be able to determine the outcome of collision events we use our smooth particle hydrodynamics (SPH) code which tracks how water is lost during such events.

  14. Cross Sections for Electron Collisions with Acetylene

    NASA Astrophysics Data System (ADS)

    Song, Mi-Young; Yoon, Jung-Sik; Cho, Hyuck; Karwasz, Grzegorz P.; Kokoouline, Viatcheslav; Nakamura, Yoshiharu; Tennyson, Jonathan

    2017-03-01

    Cross section data are compiled from the literature for electron collisions with the acetylene (HCCH) molecule. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2016.

  15. Hadron thermodynamics in relativistic nuclear collisions

    NASA Technical Reports Server (NTRS)

    Ammiraju, P.

    1985-01-01

    Various phenomenological models based on statistical thermodynamical considerations were used to fit the experimental data at high P sub T to a two temperature distribution. Whether this implies that the two temperatures belong to two different reaction mechanisms, or consequences of Lorentz-contraction factor, or related in a fundamental way to the intrinsic thermodynamics of Space-Time can only be revealed by further theoretical and experimental investigations of high P sub T phenomena in extremely energetic hadron-hadron collisions.

  16. Cross Sections for Electron Collisions with Methane

    SciTech Connect

    Song, Mi-Young Yoon, Jung-Sik; Cho, Hyuck; Itikawa, Yukikazu; Karwasz, Grzegorz P.; Kokoouline, Viatcheslav; Nakamura, Yoshiharu; Tennyson, Jonathan

    2015-06-15

    Cross section data are compiled from the literature for electron collisions with methane (CH{sub 4}) molecules. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2014.

  17. Recommended Screening Practices for Launch Collision Aviodance

    NASA Technical Reports Server (NTRS)

    Beaver, Brian A.; Hametz, Mark E.; Ollivierre, Jarmaine C.; Newman, Lauri K.; Hejduk, Matthew D.

    2015-01-01

    The objective of this document is to assess the value of launch collision avoidance (COLA) practices and provide recommendations regarding its implementation for NASA robotic missions. The scope of this effort is limited to launch COLA screens against catalog objects that are either spacecraft or debris. No modifications to manned safety COLA practices are considered in this effort. An assessment of the value of launch COLA can be broken down into two fundamental questions: 1) Does collision during launch represent a significant risk to either the payload being launched or the space environment? 2) Can launch collision mitigation be performed in a manner that provides meaningful risk reduction at an acceptable level of operational impact? While it has been possible to piece together partial answers to these questions for some time, the first attempt to comprehensively address them is documented in reference (a), Launch COLA Operations: an Examination of Data Products, Procedures, and Thresholds, Revision A. This report is the product of an extensive study that addressed fundamental technical questions surrounding launch collision avoidance analysis and practice. The results provided in reference (a) will be cited throughout this document as these two questions are addressed. The premise of this assessment is that in order to conclude that launch COLA is a value-added activity, the answer to both of these questions must be affirmative. A "no" answer to either of these questions points toward the conclusion that launch COLA provides little or no risk mitigation benefit. The remainder of this assessment will focus on addressing these two questions.

  18. Accessory deep peroneal neuropathy: collision technique diagnosis.

    PubMed

    Sander, H W; Quinto, C; Chokroverty, S

    1998-01-01

    Accessory deep peroneal nerve (ADPN), a common anatomic variant, is traditionally suspected when common peroneal nerve stimulation evokes a greater amplitude extensor digitorum brevis compound muscle action potential than deep peroneal nerve (DPN) stimulation. Posterolateral ankle stimulation over the ADPN is confirmatory. We report a rare patient with ADPN neuropathy in whom the collision technique was necessary to confirm the presence of an ADPN and to distinguish between neuropathy of the ADPN and the DPN.

  19. Catalytic reactions in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Kolomeitsev, E. E.; Tomášik, B.

    2012-06-01

    We discuss a new type of reactions of a ϕ-meson production on hyperons, πY → ϕY and antikaons -KN → ϕY. These reactions are not suppressed according to Okubo-Zweig-Iizuka rule and can be a new efficient source of ϕ mesons in a nucleus-nucleus collision. We discuss how these reactions can affect the centrality dependence and the rapidity distributions of the ϕ yield.

  20. Femtoscopy in Relativistic Heavy Ion Collisions

    SciTech Connect

    Lisa, M; Pratt, S; Soltz, R A; Wiedemann, U

    2005-07-29

    Analyses of two-particle correlations have provided the chief means for determining spatio-temporal characteristics of relativistic heavy ion collisions. We discuss the theoretical formalism behind these studies and the experimental methods used in carrying them out. Recent results from RHIC are put into context in a systematic review of correlation measurements performed over the past two decades. The current understanding of these results are discussed in terms of model comparisons and overall trends.

  1. Backward charmonium production in π N collisions

    NASA Astrophysics Data System (ADS)

    Pire, B.; Semenov-Tian-Shansky, K.; Szymanowski, L.

    2017-02-01

    The QCD collinear factorization framework allows one to describe exclusive backward production of a J /ψ meson in pion-nucleon collisions in terms of pion-to-nucleon transition distribution amplitudes. We calculate the scattering amplitude at the leading order in the strong coupling constant and estimate the cross section of this reaction in the backward kinematical region for a medium energy pion beam available at the J-Parc experimental facility.

  2. Gravity waves from cosmic bubble collisions

    SciTech Connect

    Salem, Michael P.; Saraswat, Prashant; Shaghoulian, Edgar E-mail: ps88@stanford.edu

    2013-02-01

    Our local Hubble volume might be contained within a bubble that nucleated in a false vacuum with only two large spatial dimensions. We study bubble collisions in this scenario and find that they generate gravity waves, which are made possible in this context by the reduced symmetry of the global geometry. These gravity waves would produce B-mode polarization in the cosmic microwave background, which could in principle dominate over the inflationary background.

  3. Optically controlled collisions of biological objects

    NASA Astrophysics Data System (ADS)

    Davies, Benjamin J.; Kishore, Rani; Mammen, Mathai; Helmerson, Kristian; Choi, Seok-Ki; Phillips, William D.; Whitesides, George M.

    1998-04-01

    We have developed a new assay in which two mesoscale particles are caused to collide using two independently controlled optical tweezers. This assay involves the measurement of the adhesion probability following a collision. Since the relative orientation, impact parameter (i.e., distance of closest approach), and collision velocity of the particles, as well as the components of the solution, are all under the user's control, this assay can mimic a wide range of biologically relevant collisions. We illustrate the utility of our assay by evaluating the adhesion probability of a single erythrocyte (red blood cell) to an influenza virus-coated microsphere, in the presence of sialic acid-bearing inhibitors of adhesion. This probability as a function of inhibitor concentration yields a measure of the effectiveness of the inhibitor for blocking viral adhesion. Most of the inhibition constants obtained using the tweezers agree well with those obtained from other techniques, although the inhibition constants for the best of the inhibitors were beyond the limited resolution of conventional assays. They were readily evaluated using our tweezers-based assay, however, and prove to be the most potent inhibitors of adhesion between influenza virus and erythrocytes ever measured. Further studies are underway to investigate the effect of collision velocity on the adhesion probability, with the eventual goal of understanding the various mechanisms of inhibition (direct competition for viral binding sites versus steric stabilization). Analysis of these data also provide evidence that the density of binding sites may be a crucial parameter in the application of this assay and polymeric inhibition in general.

  4. Meson interferometry in relativistic heavy ion collisions

    SciTech Connect

    Not Available

    1993-05-01

    This report contains discussions on the following topics: Recent HBT results form CERN experiment NA44; interferometry results from E802/E859/E866; recent results on two particle correlations from E814; source sizes from CERN data; intermittency and interferometry; Bose-Einstein correlations in 200A GeV S+Au collisions; HBT correlations at STAR; HBT interferometry with PHENIX; HBT calculations from ARC; three pion correlations; and pion correlations in proton-induced reactions.

  5. Novel QCD effects in nuclear collisions

    SciTech Connect

    Brodsky, S.J.

    1991-12-01

    Heavy ion collisions can provide a novel environment for testing fundamental dynamical processes in QCD, including minijet formation and interactions, formation zone phenomena, color filtering, coherent co-mover interactions, and new higher twist mechanisms which could account for the observed excess production and anomalous nuclear target dependence of heavy flavor production. The possibility of using light-cone thermodynamics and a corresponding covariant temperature to describe the QCD phases of the nuclear fragmentation region is also briefly discussed.

  6. Hyperons polarization in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Baznat, Mircea; Gudima, Konstantin; Sorin, Alexander; Teryaev, Oleg

    2017-03-01

    We study the structure of vorticity and hydrodynamic helicity fields in peripheral heavy-ion collisions using the kinetic Quark-Gluon Strings Model. The angular momentum which is a source of P-odd observables is preserved within this model with a good accuracy. We observe the formation of specific toroidal structures of vorticity field. Their existence is mirrored in the polarization of hyperons of the percent order. The observed qualitative energy dependence of polarization was predicted earlier and is quantified now.

  7. Heavy-ion collisions at the LHC

    NASA Astrophysics Data System (ADS)

    Roland, G.; Šafařík, K.; Steinberg, P.

    2014-07-01

    A new era in the study of high-energy nuclear collisions began when the CERN Large Hadron Collider (LHC) provided the first collisions of lead nuclei in late 2010. In the first three years of operation the ALICE, ATLAS and CMS experiments each collected Pb-Pb data samples of more than 50 μb at √{sNN}=2.76 TeV, exceeding the previously studied collision energies by more than an order of magnitude. These data have provided new insights into the properties of QCD matter under extreme conditions, with extensive measurements of soft particle production and newly accessible hard probes of the hot and dense medium. In this review, we provide a comprehensive overview of the results obtained in heavy-ion collisions at the LHC so far, with particular emphasis on the complementary nature of the observations by the three experiments. In particular, the combination of ALICE’s strengths at hadron identification, the strengths of ATLAS and CMS to make precise measurements of high pT probes, and the resourceful measurements of collective flow by all of the experiments have provided a rich and diverse dataset in only a few years. While the basic paradigm established at RHIC - that of a hot, dense medium that flows with a viscosity to shear-entropy ratio near the predicted lower bound, and which degrades the energy of probes, such as jets, heavy-flavours and J/ψ - is confirmed at the LHC, the new data suggest many new avenues for extracting its properties in detail.

  8. Oscillating collision of the granular chain on static wall

    NASA Astrophysics Data System (ADS)

    Ma, Liang; Huang, Decai; Chen, Weizhong; Jiao, Tengfei; Sun, Min; Hu, Fenglan; Su, Jiaye

    2017-02-01

    Collision of the granular chain on static wall is investigated by discrete element method. Collision time and traveling time are proposed on the basis of the characteristics of the collision of a single grain with a wall and the propagation of interaction force wave in a granular chain to explain the collision process. Simulation results show that an oscillating collision force is generated when the force waves successively arrive at the wall. For the collision of a mono-dispersed chain, the simulation data are in good agreement with the predicted relationship between the maximum chain length of nmax and the first maximum collision force FA. Rigid wall and soft wall are defined as nmax = 1 and nmax ≥ 2, respectively. Two similar processes of oscillating collisions occur when a light or a heavy impure grain is introduced. In these processes, two maximum collision forces, namely, FA and FB, are observed, respectively. The simulation results about the influence of the mass and position of light impure grain on the collision force FB further confirm our theoretical predictions.

  9. First in situ observations of binary raindrop collisions

    NASA Astrophysics Data System (ADS)

    Testik, F. Y.; Rahman, M. K.

    2017-01-01

    In this article, we present the first-time observations of binary raindrop collisions in rainfall events. These observations constitute a critical step in concluding a long-standing debate on the controlling physical process, binary raindrop collision versus spontaneous raindrop breakup, for the raindrop size distribution (DSD) evolution from cloud to ground level. Our raindrop collision observations were made possible by a new instrument called the High-speed Optical Disdrometer (HOD) that we recently developed for precipitation microphysics investigations. Our approximately 1 year long field campaign that covered 33 rainfall events provided 11 observations of binary raindrop collisions and outcomes but no spontaneous breakup observation. The field-observed collision rate (i.e., number of raindrop collisions within the measurement volume of the HOD per unit time) showed an increasing trend with increasing rain rate as expected from the theoretical collision rate predictions. Furthermore, the field-observed collision rates were (i) comparable (for rain rates less than approximately 50 mm/h) and (ii) significantly larger (for larger rain rates) than the theoretically predicted rates that have been used in various numerical investigations that suggest the controlling role of raindrop collisions in DSD evolution. Our observations, yet to be supplemented with observations from comprehensive field campaigns at different geographic locations and rainfall events for a definitive conclusion, support the collision-driven DSD evolution hypothesis.

  10. SPH simulations of high-speed collisions

    NASA Astrophysics Data System (ADS)

    Rozehnal, Jakub; Broz, Miroslav

    2016-10-01

    Our work is devoted to a comparison of: i) asteroid-asteroid collisions occurring at lower velocities (about 5 km/s in the Main Belt), and ii) mutual collisions of asteroids and cometary nuclei usually occurring at significantly higher relative velocities (> 10 km/s).We focus on differences in the propagation of the shock wave, ejection of the fragments and possible differences in the resultingsize-frequency distributions of synthetic asteroid families. We also discuss scaling with respect to the "nominal" target diameter D = 100 km, projectile velocity 3-7 km/s, for which a number of simulations were done so far (Durda et al. 2007, Benavidez et al. 2012).In the latter case of asteroid-comet collisions, we simulate the impacts of brittle or pre-damaged impactors onto solid monolithic targets at high velocities, ranging from 10 to 15 km/s. The purpose of this numerical experiment is to better understand impact processes shaping the early Solar System, namely the primordial asteroid belt during during the (late) heavy bombardment (as a continuation of Broz et al. 2013).For all hydrodynamical simulations we use a smoothed-particle hydrodynamics method (SPH), namely the lagrangian SPH3D code (Benz & Asphaug 1994, 1995). The gravitational interactions between fragments (re-accumulation) is simulated with the Pkdgrav tree-code (Richardson et al. 2000).

  11. Dynamics of the baseball-bat collision

    NASA Astrophysics Data System (ADS)

    Nathan, Alan M.

    2000-11-01

    A model is developed for the collision between the baseball and bat, taking into account the transverse bending vibrations of the bat. By coupling the flexible bat to the ball via a parametrized force that each mutually exerts on the other, a complete description of the collision process is obtained, including the exit speed of the ball vf. It is shown that vibrations play an important role in determining vf. The model is in excellent agreement with experimental data at low impact velocities. At the higher velocities more appropriate to the game of baseball, vf is shown to coincide with the rigid-body value only over a very small region in the barrel of the bat and to drop off sharply for impacts removed from that region. Some interesting insights into the collision process are obtained, including the observation that for impacts in the barrel of the bat, the momentum transferred to the ball is essentially complete by the time the elastic wave first arrives at the handle and that any clamping action of the hands will affect the bat at the impact point only after the ball and bat have separated. This suggests that vf is independent of the size, shape, and method of support of the bat at distances far from the impact location.

  12. Progress in Computational Electron-Molecule Collisions

    NASA Astrophysics Data System (ADS)

    Rescigno, Tn

    1997-10-01

    The past few years have witnessed tremendous progress in the development of sophisticated ab initio methods for treating collisions of slow electrons with isolated small molecules. Researchers in this area have benefited greatly from advances in computer technology; indeed, the advent of parallel computers has made it possible to carry out calculations at a level of sophistication inconceivable a decade ago. But bigger and faster computers are only part of the picture. Even with today's computers, the practical need to study electron collisions with the kinds of complex molecules and fragments encountered in real-world plasma processing environments is taxing present methods beyond their current capabilities. Since extrapolation of existing methods to handle increasingly larger targets will ultimately fail as it would require computational resources beyond any imagined, continued progress must also be linked to new theoretical developments. Some of the techniques recently introduced to address these problems will be discussed and illustrated with examples of electron-molecule collision calculations we have carried out on some fairly complex target gases encountered in processing plasmas. Electron-molecule scattering continues to pose many formidable theoretical and computational challenges. I will touch on some of the outstanding open questions.

  13. About morphological findings in fatal railway collisions.

    PubMed

    Driever, Frank; Schmidt, Peter; Madea, Burkhard

    2002-04-18

    The autopsy findings in fatal cases of railway collisions of the Bonn Institute of Legal Medicine in 1992-1999 were investigated and compared to the statements in the investigation files of the public prosecutor with regard to classification as accident or suicide as well as with regard to type and speed of collision. Of the 38 deaths, 10 were hit in an upright position, 11 fatal collisions affected persons lying outside the track and 13 were hit and overrun lying inside the track. According to the investigation classification 21 persons committed suicide (56%), while 10 died in an accident (26%). Our survey confirmed the leading role of being over-rolled in a lying position as an indication for suicides, while in accidents the upright hit was most important. With exception of the persons primarily affected between the rails in upright position and over-rolled consecutively an unequivocal assignment of injury patterns to the hit categories was possible. In cases of persons being primarily over-rolled in a lying position especially the criteria (i) opening of body cavities, (ii) organ injuries and (iii) loss of parts of the body allowed for careful conclusion on hit, respectively, overrunning speed.

  14. Multilevel Monte Carlo simulation of Coulomb collisions

    DOE PAGES

    Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; ...

    2014-05-29

    We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε , the computational cost of the method is O(ε–2) or (ε–2(lnε)2), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε–3) for direct simulation Monte Carlo or binary collision methods.more » We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10–5. Lastly, we discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.« less

  15. Multilevel Monte Carlo simulation of Coulomb collisions

    SciTech Connect

    Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; Caflisch, R. E.; Cohen, B. I.

    2014-05-29

    We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε , the computational cost of the method is O(ε–2) or (ε–2(lnε)2), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε–3) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10–5. Lastly, we discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.

  16. Initial data for black hole collisions

    NASA Astrophysics Data System (ADS)

    Rauber, J. D.

    A problem of considerable interest in relativistic astrophysics is to determine the gravitational radiation produced by collisions of compact objects, such as black holes. Such collisions may occur, for example, in the nuclei of galaxies. This problem requires that one solve the Einstein equation without limiting approximations, for example, as a Cauchy problem. Therefore, one must first construct the initial data. The extrinsic curvature on an initial spacelike hypersurface of two black holes with asisymmetric parallel spins is derived in terms of an analytic infinite series. Other two body configurations are also considered. The extrinsic curvature is constructed so that the resulting spacetime will have the topology of two Einstein-Rosen bridges; a physical equivalence of the top and bottom sheets of the initial hypersurface is also built in. It is shown that one may a priori specify the spins of the two black holes. The extrinsic curvature, so constructed, is not derivable from a potential. An appropriate numerical problem for the conformal factor is posed and examined in the above configurations. Efforts at using multi-grid differencing schemes for solving the differential equations are discussed. In order to time evolve ablack hole interaction or collision, the extrinsic curvature and conformal factor must be completely specified on an initial slice of spacetime.

  17. Initial Data for Black Hole Collisions

    NASA Astrophysics Data System (ADS)

    Rauber, Joel David

    A problem of considerable interest in relativistic astrophysics is to determine the gravitational radiation produced by collisions of compact objects, such as black holes. Such collisions may occur, for example, in the nuclei of galaxies. This problem requires that one solve the Einstein equation without limiting approximations, for example, as a Cauchy problem. Therefore, one must first construct the initial data. The extrinsic curvature on an initial spacelike hypersurface of two black holes with axisymmetric parallel spins is derived in terms of an analytic infinite series. Other two body configurations are also considered. The extrinsic curvature is constructed so that the resulting spacetime will have the topology of two Einstein-Rosen bridges; a physical equivalence of the top and bottom sheets of the initial hypersurface is also built in. It is shown that one may a priori specify the spins of the two black holes. The extrinsic curvature, so constructed, is not derivable from a potential. An appropriate numerical problem for the conformal factor is posed and examined in the above configurations. Efforts at using multi-grid differencing schemes for solving the differential equations are discussed. In order to time evolve a black hole interaction or collision, the extrinsic curvature and conformal factor must be completely specified on an initial slice of spacetime.

  18. Magmatic record of India-Asia collision

    NASA Astrophysics Data System (ADS)

    Zhu, Di-Cheng; Wang, Qing; Zhao, Zhi-Dan; Chung, Sun-Lin; Cawood, Peter A.; Niu, Yaoling; Liu, Sheng-Ao; Wu, Fu-Yuan; Mo, Xuan-Xue

    2015-09-01

    New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80-40 Ma migrated from south to north and then back to south with significant mantle input at 70-43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52-51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma.

  19. Magmatic record of India-Asia collision

    PubMed Central

    Zhu, Di-Cheng; Wang, Qing; Zhao, Zhi-Dan; Chung, Sun-Lin; Cawood, Peter A.; Niu, Yaoling; Liu, Sheng-Ao; Wu, Fu-Yuan; Mo, Xuan-Xue

    2015-01-01

    New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80–40 Ma migrated from south to north and then back to south with significant mantle input at 70–43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52–51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma. PMID:26395973

  20. Optimal filters for detecting cosmic bubble collisions

    NASA Astrophysics Data System (ADS)

    McEwen, J. D.; Feeney, S. M.; Johnson, M. C.; Peiris, H. V.

    2012-05-01

    A number of well-motivated extensions of the ΛCDM concordance cosmological model postulate the existence of a population of sources embedded in the cosmic microwave background. One such example is the signature of cosmic bubble collisions which arise in models of eternal inflation. The most unambiguous way to test these scenarios is to evaluate the full posterior probability distribution of the global parameters defining the theory; however, a direct evaluation is computationally impractical on large datasets, such as those obtained by the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck. A method to approximate the full posterior has been developed recently, which requires as an input a set of candidate sources which are most likely to give the largest contribution to the likelihood. In this article, we present an improved algorithm for detecting candidate sources using optimal filters, and apply it to detect candidate bubble collision signatures in WMAP 7-year observations. We show both theoretically and through simulations that this algorithm provides an enhancement in sensitivity over previous methods by a factor of approximately two. Moreover, no other filter-based approach can provide a superior enhancement of these signatures. Applying our algorithm to WMAP 7-year observations, we detect eight new candidate bubble collision signatures for follow-up analysis.

  1. Impulse formalism for atom-diatom collisions

    SciTech Connect

    Sharma, R.D. ); Bakshi, P.M. ); Sindoni, J.M. )

    1991-01-01

    An exact formulation of the impulse approach (IA), or quantum-mechanical spectator model, is applied to atom-diatom collisions. Results are compared with previous work on the IA, which has always involved the peaking approximation (PA). The PA is seen to overestimate (underestimate) differential cross sections for processes involving projectile atom energy loss (gain). The internal consistency of the IA is explored by subjecting it to semidetailed balancing. For small scattering angles the IA is seen to be an inadequate theory, probably due to the neglect of double- and higher-collision terms in the multiple-collision expansion of the three-body {ital T} matrix. For large scattering angles, where the IA does appear to describe the scattering process accurately, the exact calculation is shown to give the same results as when only the energy-conserving on-the-energy-shell two-body processes are considered. An accurate approximation method is also developed for rapid computation of inelastic differential cross sections. Finally, the calculated results are compared with the experimental measurements, and the need to explore two-body potentials more complicated than the hard-core potential is pointed out.

  2. New results for ultraperipheral heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Szczurek, Antoni; Kłusek-Gawenda, Mariola; Lebiedowicz, Piotr; Schäfer, Wolfgang

    2017-03-01

    We discuss diphoton semi(exclusive) production in ultraperipheral PbPb collisions at energy of √{sN N }=5.5 TeV (LHC). The nuclear calculations are based on equivalent photon approximation in the impact parameter space. The cross sections for elementary γγ → γγ subprocess are calculated including three different mechanisms: box diagrams with leptons and quarks in the loops, a VDM-Regge contribution with virtual intermediate hadronic excitations of the photons and the two-gluon exchange contribution (formally three-loops). We got relatively high cross sections in PbPb collisions. This opens a possibility to study the γγ → γγ (quasi)elastic scattering at the LHC. We find that the cross section for elastic γγ scattering could be measured in the lead-lead collisions for the diphoton invariant mass up to Wγγ ≈ 15 - 20 GeV. We identify region(s) of phase space where the two-gluon exchange contribution becomes important ingredient compared to box and nonperturbative VDM-Regge mechanisms. We discuss also first results concerning production of two e+e- pairs in UPCs of heavy ions. We considered only double scattering mechanism.

  3. RNA Polymerase II Collision Interrupts Convergent Transcription

    PubMed Central

    Hobson, David J.; Wei, Wu; Steinmetz, Lars M.; Svejstrup, Jesper Q.

    2012-01-01

    Summary Antisense noncoding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo also results in RNAPII stopping, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII polyubiquitylation, the half-life of collided polymerases increases, so that they can be detected between convergent genes. These results provide insight into fundamental mechanisms of gene traffic control and point to an unexplored effect of antisense transcription on gene regulation via polymerase collision. PMID:23041286

  4. Multilevel Monte Carlo simulation of Coulomb collisions

    SciTech Connect

    Rosin, M.S.; Ricketson, L.F.; Dimits, A.M.; Caflisch, R.E.; Cohen, B.I.

    2014-10-01

    We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε, the computational cost of the method is O(ε{sup −2}) or O(ε{sup −2}(lnε){sup 2}), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε{sup −3}) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10{sup −5}. We discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.

  5. Collisions of Rydberg Atoms with Charged Particles

    NASA Astrophysics Data System (ADS)

    MacAdam, Keith B.

    2000-10-01

    The long range of Coulomb interactions, together with the large size, long radiative lifetimes and high state densities of highly excited Rydberg atoms, results in inelastic collision cross sections of prodigious size -- often large enough to outweigh small number densities in astrophysica and cool laboratory plasmas -- and in other unusual features. This talk will provide: (a) a brief survey of the significant features of collisions between electron or positive ions and state-selected Rydberg atoms and of recent experiments( O. Makarov and K.B. MacAdam, Phys. Rev. A 60), 2131-8 (1999); and K.B. MacAdam, J.C. Day and D.M. Homan, Comm. At. Mol. Phys./Comm. Mod. Phys. 1(2), Part D, 57-73 (1999). to investigate them; (b) an introduction to some of the special techniques that have been developed(J.L. Horn, D.M. Homan, C.S. Hwang, W.L. Fuqua III and K.B. MacAdam, Rev. Sci. Instrum. 69), 4086-93 (1998). for preparation, manipulation and detection of Rydberg atoms; and (c) a glimpse at new directions in Rydberg atom collision research.

  6. Collisions of Biological Objects Using Optical Tweezers

    NASA Astrophysics Data System (ADS)

    Helmerson, K.; Davies, B. J.; Kishore, R.; Phillips, W. D.; Mammen, M.; Choi, S.-K.; Whitesides, G. M.

    1997-04-01

    We have developed a new functional assay in which two mesoscale particles are caused to collide using two independently controlled optical tweezers. This assay involved measurement of the probability of adhesion on collision. Since the components of the solution, the orientation, and the relative collision velocity are all under the user's control, this assay can mimic closely a range of types of collisions involving biological objects. We illustrate the utility of our assay by evaluating the probability of adhesion of a single erythrocyte to a virus-coated microsphere, in the presence of a sialic acid-bearing inhibitor(M. Mammen, et al., Chemistry and Biology 3: 757-63 (1996).). This probability as a function of the concentration of the inhibitor is a measure of the effectiveness of the inhibitor; most of the inhibition constants obtained using optical tweezers agree well with those obtained from other techniques. Inhibition constants for the most effective inhibitors could not be measured using other types of assays; however, they were readily obtained using our optical tweezers based assay. The best inhibitor is the most potent inhibitor of attachment of influenza virus to erythrocytes ever measured.

  7. Hard hadronic collisions: extrapolation of standard effects

    SciTech Connect

    Ali, A.; Aurenche, P.; Baier, R.; Berger, E.; Douiri, A.; Fontannaz, M.; Humpert, B.; Ingelman, G.; Kinnunen, R.; Pietarinen, E.

    1984-01-01

    We study hard hadronic collisions for the proton-proton (pp) and the proton-antiproton (p anti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN p anti p Collider, and with the help of quantum chromodynamics (QCD), we extrapolate to the next generation of hadron colliders with a centre-of-mass energy E/sub cm/ = 10 to 20 TeV. We estimate various signatures, trigger rates, event topologies, and associated distributions for a variety of old and new physical processes, involving prompt photons, leptons, jets, W/sup + -/ and Z bosons in the final state. We also calculate the maximum fermion and boson masses accessible at the LEP Hadron Collider. The standard QCD and electroweak processes studied here, being the main body of standard hard collisions, quantify the challenge of extracting new physics with hadron colliders. We hope that our estimates will provide a useful profile of the final states, and that our experimental physics colleagues will find this of use in the design of their detectors. 84 references.

  8. Magmatic record of India-Asia collision.

    PubMed

    Zhu, Di-Cheng; Wang, Qing; Zhao, Zhi-Dan; Chung, Sun-Lin; Cawood, Peter A; Niu, Yaoling; Liu, Sheng-Ao; Wu, Fu-Yuan; Mo, Xuan-Xue

    2015-09-23

    New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80-40 Ma migrated from south to north and then back to south with significant mantle input at 70-43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52-51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma.

  9. Effects of overlapping strings in pp collisions

    DOE PAGES

    Bierlich, Christian; Gustafson, Gösta; Lönnblad, Leif; ...

    2015-03-26

    In models for hadron collisions based on string hadronization, the strings are usually treated as independent, allowing no interaction between the confined colour fields. In studies of nucleus collisions it has been suggested that strings close in space can fuse to form "colour ropes." Such ropes are expected to give more strange particles and baryons, which also has been suggested as a signal for plasma formation. Overlapping strings can also be expected in pp collisions, where usually no phase transition is expected. In particular at the high LHC energies the expected density of strings is quite high. To investigate possiblemore » effects of rope formation, we present a model in which strings are allowed to combine into higher multiplets, giving rise to increased production of baryons and strangeness, or recombine into singlet structures and vanish. Also a crude model for strings recombining into junction structures is considered, again giving rise to increased baryon production. The models are implemented in the DIPSY MC event generator, using PYTHIA8 for hadronization, and comparison to pp minimum bias data, reveals improvement in the description of identified particle spectra.« less

  10. High gluon densities in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Blaizot, Jean-Paul

    2017-03-01

    The early stages of heavy ion collisions are dominated by high density systems of gluons that carry each a small fraction x of the momenta of the colliding nucleons. A distinguishing feature of such systems is the phenomenon of ‘saturation’ which tames the expected growth of the gluon density as the energy of the collision increases. The onset of saturation occurs at a particular transverse momentum scale, the ‘saturation momentum’, that emerges dynamically and that marks the onset of non-linear gluon interactions. At high energy, and for large nuclei, the saturation momentum is large compared to the typical hadronic scale, making high density gluons amenable to a description with weak coupling techniques. This paper reviews some of the challenges faced in the study of such dense systems of small x gluons, and of the progress made in addressing them. The focus is on conceptual issues, and the presentation is both pedagogical, and critical. Examples where high gluon density could play a visible role in heavy ion collisions are briefly discussed at the end, for illustration purpose.

  11. Half collision resonance phenomena in molecules

    SciTech Connect

    Maximo Garcia-Sucre ); Raseev, G. ); Ross, S.C. )

    1991-01-01

    The Escuela Latinoamericana de Fisica (ELAF) is a series of meeting s that for 28 years has played an important role in research-level teaching of physics in Latin America. This book contains the proceedings of ELAF 90 which was held at the Instituto Venezolano de Investigaciones Cientificas (IVIC) in Caracas, Venezuela from July 23 to August 3, 1990, as part of the commemoration of the 30th anniversary of IVIC. In contrast to previous ELAF's that were of general scope, ELAF 90 centered on a particular subject matter: Half Collisional Resonance Phenomena in Molecules, Experimental and Theoretical Approaches. The term Half Collision'' refers to the fragmentation of a molecular system following is excitation by light. The lack of an incident fragmentation of a molecular system following is excitation by light. The lack of an incident particle (other than the photon) in the fragmentation process is what leads to the term. The purpose of this volume is to present current results in the experimental and theoretical study of half collisions and also to include pedagogical papers at an introductory or intermediate level. The contributions are grouped into several sections; light sources; ionization; dissociation-experimental; dissociation-theory; competition between ionization and dissociation; and particle-molecule collisions.

  12. Convolution Inequalities for the Boltzmann Collision Operator

    NASA Astrophysics Data System (ADS)

    Alonso, Ricardo J.; Carneiro, Emanuel; Gamba, Irene M.

    2010-09-01

    We study integrability properties of a general version of the Boltzmann collision operator for hard and soft potentials in n-dimensions. A reformulation of the collisional integrals allows us to write the weak form of the collision operator as a weighted convolution, where the weight is given by an operator invariant under rotations. Using a symmetrization technique in L p we prove a Young’s inequality for hard potentials, which is sharp for Maxwell molecules in the L 2 case. Further, we find a new Hardy-Littlewood-Sobolev type of inequality for Boltzmann collision integrals with soft potentials. The same method extends to radially symmetric, non-increasing potentials that lie in some {Ls_{weak}} or L s . The method we use resembles a Brascamp, Lieb and Luttinger approach for multilinear weighted convolution inequalities and follows a weak formulation setting. Consequently, it is closely connected to the classical analysis of Young and Hardy-Littlewood-Sobolev inequalities. In all cases, the inequality constants are explicitly given by formulas depending on integrability conditions of the angular cross section (in the spirit of Grad cut-off). As an additional application of the technique we also obtain estimates with exponential weights for hard potentials in both conservative and dissipative interactions.

  13. Effects of overlapping strings in pp collisions

    SciTech Connect

    Bierlich, Christian; Gustafson, Gösta; Lönnblad, Leif; Tarasov, Andrey

    2015-03-26

    In models for hadron collisions based on string hadronization, the strings are usually treated as independent, allowing no interaction between the confined colour fields. In studies of nucleus collisions it has been suggested that strings close in space can fuse to form "colour ropes." Such ropes are expected to give more strange particles and baryons, which also has been suggested as a signal for plasma formation. Overlapping strings can also be expected in pp collisions, where usually no phase transition is expected. In particular at the high LHC energies the expected density of strings is quite high. To investigate possible effects of rope formation, we present a model in which strings are allowed to combine into higher multiplets, giving rise to increased production of baryons and strangeness, or recombine into singlet structures and vanish. Also a crude model for strings recombining into junction structures is considered, again giving rise to increased baryon production. The models are implemented in the DIPSY MC event generator, using PYTHIA8 for hadronization, and comparison to pp minimum bias data, reveals improvement in the description of identified particle spectra.

  14. Liquid droplet radiator development status

    NASA Technical Reports Server (NTRS)

    White, K. Alan, III

    1987-01-01

    Development of the Liquid Droplet Radiator (LDR) is described. Significant published results of previous investigators are presented, and work currently in progress is discussed. Several proposed LDR configurations are described, and the rectangular and triangular configurations currently of most interest are examined. Development of the droplet generator, collector, and auxiliary components are discussed. Radiative performance of a droplet sheet is considered, and experimental results are seen to be in very good agreement with analytical predictions. The collision of droplets in the droplet sheet, the charging of droplets by the space plasma, and the effect of atmospheric drag on the droplet sheet are shown to be of little consequence, or can be minimized by proper design. The LDR is seen to be less susceptible than conventional technology to the effects of micrometeoroids or hostile threats. The identification of working fluids which are stable in the orbital environments of interest is also made. Methods for reducing spacecraft contamination from an LDR to an acceptable level are discussed. Preliminary results of microgravity testing of the droplet generator are presented. Possible future NASA and Air Force missions enhanced or enabled by a LDR are also discussed. System studies indicate that the LDR is potentially less massive than heat pipe radiators. Planned microgravity testing aboard the Shuttle or space station is seen to be a logical next step in LDR development.

  15. Melting and burning solids into liquids and gases.

    PubMed

    Losasso, Frank; Irving, Geoffrey; Guendelman, Eran; Fedkiw, Ron

    2006-01-01

    We propose a novel technique for melting and burning solid materials, including the simulation of the resulting liquid and gas. The solid is simulated with traditional mesh-based techniques (triangles or tetrahedra) which enable robust handling of both deformable and rigid objects, collision and self-collision, rolling, friction, stacking, etc. The subsequently created liquid or gas is simulated with modern grid-based techniques, including vorticity confinement and the particle level set method. The main advantage of our method is that state-of-the-art techniques are used for both the solid and the fluid without compromising simulation quality when coupling them together or converting one into the other. For example, we avoid modeling solids as Eulerian grid-based fluids with high viscosity or viscoelasticity, which would preclude the handling of thin shells, self-collision, rolling, etc. Thus, our method allows one to achieve new effects while still using their favorite algorithms (and implementations) for simulating both solids and fluids, whereas other coupling algorithms require major algorithm and implementation overhauls and still fail to produce rich coupling effects (e.g., melting and burning solids).

  16. Dynamics of liquid-liquid displacement.

    PubMed

    Fetzer, Renate; Ramiasa, Melanie; Ralston, John

    2009-07-21

    Capillary driven liquid-liquid displacement in a system with two immiscible liquids of comparable viscosity was investigated by means of optical high speed video microscopy. For the first time, the impact of substrate wettability on contact line dynamics in liquid-liquid systems was studied. On all substrates, qualitatively different dynamics, in two distinct velocity regimes, were found. Hydrodynamic models apply to the fast stage of initial spreading, while nonhydrodynamic dissipation dominates contact line motion in a final stage at low speed, where the molecular kinetic theory (MKT) successfully captured the dynamics. The MKT model parameter values showed no systematic dependence on substrate wettability. This unexpected result is interpreted in terms of local contact line pinning.

  17. Critical condition in gravitational shock wave collision and heavy ion collisions

    SciTech Connect

    Lin Shu; Shuryak, Edward

    2011-02-15

    In this paper, we derive a critical condition for matter equilibration in heavy ion collisions using a holographic approach. Gravitational shock waves with infinite transverse extension are used to model an infinite nucleus. We construct the trapped surface in the collision of two asymmetric planar shock waves with sources at different depth in the bulk AdS and formulate a critical condition for matter equilibration in the collision of ''nuclei'' in the dual gauge theory. We find the critical condition is insensitive to the depth of the source closer to the AdS boundary. To understand the origin of the critical condition, we compute the Next-to-Leading Order stress tensor in the boundary field theory due to the interaction of the nuclei and find that the critical condition corresponds to the breaking down of the perturbative expansion. We expect nonperturbative effects are needed to describe black hole formation.

  18. Precision liquid level sensor

    DOEpatents

    Field, M.E.; Sullivan, W.H.

    A precision liquid level sensor utilizes a balanced bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

  19. Liquid medication administration

    MedlinePlus

    ... easily. Oral syringes have some advantages for giving liquid medicines. They are accurate. They are easy to ... cups are also a handy way to give liquid medicines. However, dosing errors have occurred with them. ...

  20. Contributions of collision rate and collision efficiency to erythrocyte aggregation in postcapillary venules at low flow rates.

    PubMed

    Kim, Sangho; Zhen, Janet; Popel, Aleksander S; Intaglietta, Marcos; Johnson, Paul C

    2007-09-01

    Red blood cell aggregation at low flow rates increases venous vascular resistance, but the process of aggregate formation in these vessels is not well understood. We previously reported that aggregate formation in postcapillary venules of the rat spinotrapezius muscle mainly occurs in a middle region between 15 and 30 microm downstream from the entrance. In light of the findings in that study, the main purpose of this study was to test two hypotheses by measuring collision frequency along the length of the venules during low flow. We tested the hypothesis that aggregation rarely occurs in the initial 15-microm region of the venule because collision frequency is very low. We found that collision frequency was lower than in other regions, but collision efficiency (the ratio of aggregate formation to collisions) was almost nil in this region, most likely because of entrance effects and time required for aggregation. Radial migration of red blood cells and Dextran 500 had no effect on collision frequency. We also tested the hypothesis that aggregation was reduced in the distal venule region because of the low aggregability of remaining nonaggregated cells. Our findings support this hypothesis, since a simple model based on the ratio of aggregatable to nonaggregatable red blood cells predicts the time course of collision efficiency in this region. Collision efficiency averaged 18% overall but varied from 0 to 52% and was highest in the middle region. We conclude that while collision frequency influences red blood cell aggregate formation in postcapillary venules, collision efficiency is more important.

  1. Coastal river plumes: Collisions and coalescence

    USGS Publications Warehouse

    Warrick, Jonathan; Farnsworth, Katherine L

    2017-01-01

    Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world’s coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas < 10,000 km2), such as found along most active geologic coastal margins, were much more likely to have river plumes that collide and interact than coastal settings with large rivers (watershed areas > 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world’s smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and

  2. Coastal river plumes: Collisions and coalescence

    NASA Astrophysics Data System (ADS)

    Warrick, Jonathan A.; Farnsworth, Katherine L.

    2017-02-01

    Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world's coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas < 10,000 km2), such as found along most active geologic coastal margins, were much more likely to have river plumes that collide and interact than coastal settings with large rivers (watershed areas > 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world's smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of

  3. Conservative bin-to-bin fractional collisions

    NASA Astrophysics Data System (ADS)

    Martin, Robert

    2016-11-01

    Particle methods such as direct simulation Monte Carlo (DSMC) and particle-in-cell (PIC) are commonly used to model rarefied kinetic flows for engineering applications because of their ability to efficiently capture non-equilibrium behavior. The primary drawback to these methods relates to the poor convergence properties due to the stochastic nature of the methods which typically rely heavily on high degrees of non-equilibrium and time averaging to compensate for poor signal to noise ratios. For standard implementations, each computational particle represents many physical particles which further exacerbate statistical noise problems for flow with large species density variation such as encountered in flow expansions and chemical reactions. The stochastic weighted particle method (SWPM) introduced by Rjasanow and Wagner overcome this difficulty by allowing the ratio of real to computational particles to vary on a per particle basis throughout the flow. The DSMC procedure must also be slightly modified to properly sample the Boltzmann collision integral accounting for the variable particle weights and to avoid the creation of additional particles with negative weight. In this work, the SWPM with necessary modification to incorporate the variable hard sphere (VHS) collision cross section model commonly used in engineering applications is first incorporated into an existing engineering code, the Thermophysics Universal Research Framework. The results and computational efficiency are compared to a few simple test cases using a standard validated implementation of the DSMC method along with the adapted SWPM/VHS collision using an octree based conservative phase space reconstruction. The SWPM method is then further extended to combine the collision and phase space reconstruction into a single step which avoids the need to create additional computational particles only to destroy them again during the particle merge. This is particularly helpful when oversampling the

  4. Conjunctions and Collision Avoidance with Electrodynamic Tethers

    NASA Astrophysics Data System (ADS)

    Levin, E.

    2013-09-01

    Electrodynamic propulsion technology is currently in development by NASA, ESA, and JAXA for the purpose of affordable removal of large debris objects from LEO. At the same time, the Naval Research Laboratory is preparing a 3U CubeSat with a 1-km electrodynamic tether for a flight demonstration of electrodynamic propulsion. This type of propulsion does not require fuel. The electrodynamic thrust is the Lorentz force acting on the electric current in a long conductor (tether) in the geomagnetic field. Electrons are collected from the ambient plasma on one end and emitted back into the plasma from the other end. The electric current loop is closed through the ionosphere, as demonstrated in two previous flights. The vehicle is solar powered. To support safe navigation of electrodynamic tethers, proper conjunction analysis and collision avoidance strategies are needed. The typical lengths of electrodynamic tethers for near-term applications are measured in kilometers, and the conjunction geometry is very different from the geometry of conjunctions between compact objects. It is commonly thought that the collision cross-section in a conjunction between a tether and a compact object is represented by the product of the tether length and the size of the object. However, rigorous analysis shows that this is not the case, and that the above assumption leads to grossly overestimated collision probabilities. The paper will present the results of a detailed mathematical analysis of the conjunction geometry and collision probabilities in close approaches between electrodynamic tethers and compact objects, such as satellites, rocket bodies, and debris fragments. Electrodynamic spacecraft will not require fuel, and therefore, can thrust constantly. Their orbit transfers can take many days, but can result in major orbit changes, including large rotations of the orbital plane, both in the inclination and the node. During these orbit transfers, the electrodynamic spacecraft will

  5. Passenger car collision fatalities--with special emphasis on collisions with heavy vehicles.

    PubMed

    Björnstig, Ulf; Björnstig, Johanna; Eriksson, Anders

    2008-01-01

    Between 1995 and 2004, 293 passenger car occupants died in collisions with other vehicles in northern Sweden (annual incidence: 3.3 per 100,000 inhabitants, 6.9 per 100,000 cars, or 4.8 per 10(9)km driven); half of these deaths involved heavy vehicles. The annual number of passenger car occupant deaths per 100,000 cars in car-truck/bus collisions has remained unchanged since the 1980s, but in car-car collisions it has decreased to one third of its former level. As crash objects, trucks and buses killed five times as many car occupants per truck/bus kilometer driven as did cars. The collisions were characterized by crashes in the oncoming vehicle's lane, under icy, snowy, or wet conditions; crashes into heavy vehicles generally occurred in daylight, on workdays, in winter, and on 90 and 70 km/h two-lane roads. Head and chest injuries accounted for most of the fatal injuries. Multiple fatal injuries and critical and deadly head injuries characterized the deaths in collisions with heavy vehicles. An indication of suicide was present in 4% of the deaths; for those who crashed into trucks, this percentage was doubled. Among the driver victims, 4% had blood alcohol levels above the legal limit of 0.2g/L. Frontal collision risks might be reduced by a mid-barrier, by building less injurious fronts on trucks and buses, by efficient skid prevention, and by use of flexible speed limits varying with road and light conditions.

  6. Liquid level sensing device

    DOEpatents

    Tokarz, Richard D.

    1983-01-01

    A liquid level sensing device comprising a load cell supporting a column or stack of segments freely resting on one another. The density of each element is substantially identical to that of the surrounding liquid. The elements are freely guided within a surrounding tube. As each element is exposed above the liquid level, its weight will be impressed through the column to the load cell, thereby providing a signal at the load cell directly proportional to the liquid level elevation.

  7. Lambda Polarization in Lead-Lead Collisions

    NASA Astrophysics Data System (ADS)

    Schillings, Eelco

    2003-05-01

    In this thesis the production and polarization of Lambda particles produced in Pb-Pb collisions at a beam energy of 158 GeV/c per nucleon are studied. In these collisions nuclear matter is compressed and heated and under these conditions it is possible that a quark-gluon plasma (QGP) is created. In a QGP the boundaries between individual particles disappear and the quarks and gluons can move around freely. One of the probes to study the creation of the QGP is the so-called Strangeness Enhancement, which is the enhanced production of strange particles, with respect to the production in proton-induced collisions. Another proposed signature of the QGP is the disappearance of transverse Lambda polarization around mid-rapidity. Transverse Lambda polarization can occur when the spin of the produced Lambda has its preferred direction perpendicular to the production plane. In proton-proton and proton-nucleus collisions a negative transverse polarization has been observed and its magnitude was largest for the Lambdas produced in the direction of the beam (i.e. at high xF). This is an indication that the projectile plays an important role and in semi-classical models the following picture is assumed: in the interaction region a spin-zero ud-diquark from the projectile recombines with a negatively polarized s-quark from the sea. This s-quark also gives transverse momentum (pT) to the Lambda and as a result the polarization is dependent on pT. Recently it has been shown that also in nucleus-nucleus collisions a negative transverse polarization occurs, so even in large interaction regions the information on the nature of the projectile is kept. In a QGP however this information is lost and no production plane can be defined. This will cause the transverse polarization of the Lambdas produced in this region to disappear. The transverse polarization of the produced Lambdas has been measured in the NA57 experiment at CERN around two values of xF: for xF = 0.09 a value of +0.6 +7

  8. Factorization, the Glasma and the Ridge in heavy ion collisions

    SciTech Connect

    Venugopalan, Raju

    2008-10-13

    High energy heavy ion collisions can be efficiently described as the collision of two sheets of Color Glass Condensate. The dynamics of the collision can be studied ab initio in a systematic effective field theory approach. This requires factorization theorems that separate the initial state evolution of the wave functions with energy from the final state interactions that produce matter with high energy densities called the Glasma. We discuss how this matter is formed, its remarkable properties and its relevance for understanding thermalization of the Quark Gluon Plasma in heavy ion collisions. Long range rapidity correlations in the collision that have a remarkable ridge like structure may allow us to probe early times in the collision and infer directly the properties of the Glasma.

  9. UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS.

    SciTech Connect

    STEINBERG,P.A.FOR THE PHOBOS COLLABORATION

    2002-07-24

    The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at {radical}(s{sub NN}) = 19.6, 130 and 200 GeV. Two observations indicate universal behavior of charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/{bar p}p and e{sup +}e{sup -} data. / in nuclear collisions at high energy scales with {radical}s in a similar way as N{sub ch} in e{sup +}e{sup -} collisions and has a very weak centrality dependence. These features may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.

  10. Macroscopic liquid-state molecular hydrodynamics

    PubMed Central

    Keanini, R. G.; Tkacik, Peter T.; Fleischhauer, Eric; Shahinian, Hossein; Sholar, Jodie; Azimi, Farzad; Mullany, Brid

    2017-01-01

    Experimental evidence and theoretical modeling suggest that piles of confined, high-restitution grains, subject to low-amplitude vibration, can serve as experimentally-accessible analogs for studying a range of liquid-state molecular hydrodynamic processes. Experiments expose single-grain and multiple-grain, collective dynamic features that mimic those either observed or predicted in molecular-scale, liquid state systems, including: (i) near-collision-time-scale hydrodynamic organization of single-molecule dynamics, (ii) nonequilibrium, long-time-scale excitation of collective/hydrodynamic modes, and (iii) long-time-scale emergence of continuum, viscous flow. In order to connect directly observable macroscale granular dynamics to inaccessible and/or indirectly measured molecular hydrodynamic processes, we recast traditional microscale equilibrium and nonequilibrium statistical mechanics for dense, interacting microscale systems into self-consistent, macroscale form. The proposed macroscopic models, which appear to be new with respect to granular physics, and which differ significantly from traditional kinetic-theory-based, macroscale statistical mechanics models, are used to rigorously derive the continuum equations governing viscous, liquid-like granular flow. The models allow physically-consistent interpretation and prediction of observed equilibrium and non-equilibrium, single-grain, and collective, multiple-grain dynamics. PMID:28139711

  11. Macroscopic liquid-state molecular hydrodynamics

    NASA Astrophysics Data System (ADS)

    Keanini, R. G.; Tkacik, Peter T.; Fleischhauer, Eric; Shahinian, Hossein; Sholar, Jodie; Azimi, Farzad; Mullany, Brid

    2017-01-01

    Experimental evidence and theoretical modeling suggest that piles of confined, high-restitution grains, subject to low-amplitude vibration, can serve as experimentally-accessible analogs for studying a range of liquid-state molecular hydrodynamic processes. Experiments expose single-grain and multiple-grain, collective dynamic features that mimic those either observed or predicted in molecular-scale, liquid state systems, including: (i) near-collision-time-scale hydrodynamic organization of single-molecule dynamics, (ii) nonequilibrium, long-time-scale excitation of collective/hydrodynamic modes, and (iii) long-time-scale emergence of continuum, viscous flow. In order to connect directly observable macroscale granular dynamics to inaccessible and/or indirectly measured molecular hydrodynamic processes, we recast traditional microscale equilibrium and nonequilibrium statistical mechanics for dense, interacting microscale systems into self-consistent, macroscale form. The proposed macroscopic models, which appear to be new with respect to granular physics, and which differ significantly from traditional kinetic-theory-based, macroscale statistical mechanics models, are used to rigorously derive the continuum equations governing viscous, liquid-like granular flow. The models allow physically-consistent interpretation and prediction of observed equilibrium and non-equilibrium, single-grain, and collective, multiple-grain dynamics.

  12. Liquid detection circuit

    DOEpatents

    Regan, Thomas O.

    1987-01-01

    Herein is a circuit which is capable of detecting the presence of liquids, especially cryogenic liquids, and whose sensor will not overheat in a vacuum. The circuit parameters, however, can be adjusted to work with any liquid over a wide range of temperatures.

  13. Renewable liquid reflection grating

    DOEpatents

    Ryutov, Dmitri D.; Toor, Arthur

    2003-10-07

    A renewable liquid reflection grating. Electrodes are operatively connected to a conducting liquid in an arrangement that produces a reflection grating and driven by a current with a resonance frequency. In another embodiment, the electrodes create the grating by a resonant electrostatic force acting on a dielectric liquid.

  14. Liquid metal cold trap

    DOEpatents

    Hundal, Rolv

    1976-01-01

    A cold trap assembly for removing impurities from a liquid metal being provided with a hole between the incoming impure liquid metal and purified outgoing liquid metal which acts as a continuous bleed means and thus prevents the accumulation of cover gases within the cold trap assembly.

  15. Multiplicity and theremalization time in heavy-ions collisions

    NASA Astrophysics Data System (ADS)

    Aref'eva, Irina

    2016-10-01

    We present a concise review of quark-gluon plasma formation in heavy-ions collisions within the holographic approach. In particular, we discuss how to get the total multiplicity in heavy ions collision to fit the recent experimental data. We also discuss theoretical estimations of time formation of QGP in heavy ions collision and show that different observables can give the different times of QGP formation.

  16. Onset of deconfinement in nucleus-nucleus collisions

    SciTech Connect

    Gazdzicki, M.; Gorenstein, M. I.; Seyboth, P.

    2012-05-15

    The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals anomalies-the kink, horn, and step. They were predicted as signals of the deconfinement phase transition and observed by the NA49 Collaboration in central PbPb collisions at the CERN SPS. This indicates the onset of the deconfinement in nucleus-nucleus collisions at about 30 A GeV.

  17. On the orbital dependence of the asteroidal collision process

    NASA Technical Reports Server (NTRS)

    Ip, W.-H.

    1977-01-01

    Collision of asteroids with the main-belt asteroid population is considered with the effect of the impact kinetic energy taken into account. It is found that objects in eccentric orbits have a larger probability of destructive collision as compared to objects in orbits with mean values of eccentricity (equal to 0.15) and inclination (equal to 10 deg); also orbits with small semimajor axes (about 2.3 AU) are found to have peak values of the probability of destructive collision.

  18. Differential form of the collision integral for a relativistic plasma

    SciTech Connect

    Braams, B.J.; Karney, C.F.F.

    1987-08-01

    A differential formulation for the Beliaev and Budker relativistic collision integral is presented. This permits the rapid numerical evaluation of the collision integral. The decomposition into spherical harmonics allows the collision operator to be expressed in terms of one-dimensional integrals for simple background distributions. This is useful in carrying out analytical work. It also provides a convenient method for calculating the boundary conditions for the potentials. 6 refs.

  19. High baryon density from relativistic heavy ion collisions

    SciTech Connect

    Pang, Y.; Kahana, S.H.; Schlagel, T.J. |

    1993-10-01

    A quantitative model, based on hadronic physics, is developed and applied to heavy ion collisions at BNL-AGS energies. This model is in excellent agreement with observed particle spectra in heavy ion collisions using Si beams, where baryon densities of three and four times the normal nuclear matter density ({rho}{sub 0}) are reached. For Au on Au collisions, the authors predict the formation of matter at very high densities (up to 10 {rho}{sub 0}).

  20. Traffic volume and collisions involving transit and nontransit vehicles.

    PubMed

    Ragland, D R; Hundenski, R J; Holman, B L; Fisher, J M

    1992-10-01

    This study reports an analysis of collisions occurring between public transit vehicles operated by the San Francisco Municipal Railway System (Muni), the public transit agency for the City of San Francisco, and nontransit vehicles. The analysis, focusing on weekday collisions during 1987, demonstrated a strong association between hourly transit collisions rates and hourly traffic volume. The collision rate varied from 0.01 per 1,000 Muni vehicle-hours of operation during the interval 5 A.M. to 6 A.M., a time of very low traffic volume, to 0.93 (approximately 1 collision per 1,000 Muni vehicle-hours of operation) during the interval 5 P.M. to 6 P.M., a time of very high traffic volume. Using a power function to predict either the total number of collisions, or the rate of collisions per 1,000 Muni vehicle-hours, almost 90% of total variation was accounted for by traffic volume. A very similar pattern was found for collisions judged either avoidable or unavoidable. A peak in the collision rate between 2 A.M. and 3 A.M. could not be accounted for by traffic volume alone. That peak occurred in the one-hour interval following the 2 A.M. closing of bars in San Francisco, and was composed entirely of a sharp increase in unavoidable collisions. Increasing traffic volume appeared to operate through two mechanisms: (i) an increase in the number of opportunities for a collision, defined as a quantity proportional to the product of the number of Muni and non-Muni vehicles; (ii) an increase in the probability of a collision occurring between any given pair of vehicles.

  1. Introduction to the study of collisions between heavy nuclei

    SciTech Connect

    Bayman, B.F.

    1980-01-01

    Current investigations concerning the collisions of nuclei governed by small de Broglie wavelengths are reviewed. The wave packets localize nuclei in regions small compared to their diameters. Cross sections are examined for potential scattering, elastic scattering, quasi-molecular states, peripheral particle-transfer reactions, fusion, and deep inelastic collisions. Theories of fusion and deep inelastic collisions are summarized. This paper is in the nature of a review-tutorial. 45 references, 51 figures, 2 tables. (RWR)

  2. Exact linearized Coulomb collision operator in the moment expansion

    SciTech Connect

    Ji, Jeong -Young; Held, Eric D.

    2006-10-05

    In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collision operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Furthermore, useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.

  3. Squeezed States and Particle Production in High Energy Collisions

    NASA Technical Reports Server (NTRS)

    Bambah, Bindu A.

    1996-01-01

    Using the 'quantum optical approach' we propose a model of multiplicity distributions in high energy collisions based on squeezed coherent states. We show that the k-mode squeezed coherent state is the most general one in describing hadronic multiplicity distributions in particle collision processes, describing not only p(bar-p) collisions but e(+)e(-), vp and diffractive collisions as well. The reason for this phenomenological fit has been gained by working out a microscopic theory in which the squeezed coherent sources arise naturally if one considers the Lorentz squeezing of hadrons and works in the covariant phase space formalism.

  4. New Caledonia a classic example of an arc continent collision

    NASA Astrophysics Data System (ADS)

    Aitchison, J.

    2011-12-01

    The SW Pacific island of New Caledonia presents a classic example of an arc-continent collision. This event occurred in the Late Eocene when elements of an intra-oceanic island arc system, the Loyalty-D'Entrecasteaux arc, which stretched SSE from near Papua New Guinea east of New Caledonia to offshore New Zealand, collided with micro-continental fragments that had rifted off eastern Gondwana (Australia) in the late Cretaceous. Intervening Late Cretaceous to Paleogene oceanic crust of the South Loyalty Basin was eliminated through eastward subduction beneath this west-facing intra-oceanic island arc. As with many arc-continent collisions elsewhere collision was accompanied by ophiolite emplacement. The erosional remnants of which are extensive in New Caledonia. Collision led to subduction flip, followed by extensive rollback in front of the newly established east-facing Vitiaz arc. Post-collisional magmatism occurred after slab break-off and is represented by small-scale granitoid intrusions. Additional important features of New Caledonia include the presence of a regionally extensive UHP metamorphic terrain consisting of blueschists and eclogites that formed during the subduction process and were rapidly exhumed as a result of the collision Not only was collision and associated orogeny short-lived this collision system has not been overprinted by any major subsequent collision. New Caledonia thus provides an exceptional location for the study of processes related to arc-continent collision in general.

  5. A new technique for predicting geosynchronous satellite collision probability

    NASA Technical Reports Server (NTRS)

    Mccormick, B.

    1986-01-01

    A new technique has been developed to predict the probability of an expired geosynchronous satellite colliding with an active satellite. This new technique employs deterministic methods for modeling the motion of satellites and applies statistical techniques to estimate the collision probability. The collision probability is used to estimate the expected time between collisions based on realistic distributions of expired and active satellites. The primary advantage of this new technique is that realistic distributions can be used in the prediction process instead of uniform distributions as has been used in previous techniques. The expected time between collisions based on a current NORAD database is estimated to be in the hundreds of years.

  6. Improved intra-species collision models for PIC simulations

    SciTech Connect

    Jones, M.E.; Lemons, D.S.; Winske, D.

    1998-07-01

    In recent years, the authors have investigated methods to improve the effectiveness of modeling collisional processes in particle-in-cell codes. Through the use of generalized collision models, plasma dynamics can be followed both in the regime of nearly collisionless plasmas as well as in the hydrodynamic limit of collisional plasmas. They have developed a collision-field method to treat both the case of collisions between unlike plasma species (inter-species collisions), through the use of a deterministic, grid-based force, and between particles of the same species (intra-species collisions), through the use of a Langevin equation. While the approach used for inter-species collisions is noise-free in that the collision experienced by a particle does not require any random numbers, such random numbers are used for intra-species collisions. This gives rise to a stochastic cooling effect inherent in the Langevin approach. In this paper, the authors concentrate on intra-species collisions and describe how the accuracy of the model can be improved by appropriate corrections to velocity and spatial moments.

  7. Exact linearized Coulomb collision operator in the moment expansion

    SciTech Connect

    Ji, Jeong-Young; Held, Eric D.

    2006-10-15

    In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collision operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.

  8. A New Aloha Anti-Collision Algorithm Based on CDMA

    NASA Astrophysics Data System (ADS)

    Bai, Enjian; Feng, Zhu

    The tags' collision is a common problem in RFID (radio frequency identification) system. The problem has affected the integrity of the data transmission during the process of communication in the RFID system. Based on analysis of the existing anti-collision algorithm, a novel anti-collision algorithm is presented. The new algorithm combines the group dynamic frame slotted Aloha algorithm with code division multiple access technology. The algorithm can effectively reduce the collision probability between tags. Under the same number of tags, the algorithm is effective in reducing the reader recognition time and improve overall system throughput rate.

  9. Pedestrian Oriented Vehicular Collision Avoidance Support System: P-VCASS

    NASA Astrophysics Data System (ADS)

    Wada, Tomotaka; Nakanishi, Yuki; Yamaguchi, Ryohta; Fujimoto, Kazushi; Okada, Hiromi

    In recent years, researchers have studied extensively about vehicle collision avoidance. The authors have developed Vehicular Collision Avoidance Support System (VCASS) based on IVC in order to prevent a vehicular collision beforehand. The system grasps the relative locations of vehicles by exchanging the GPS information in each vehicle. Then the system warns drivers if it detects some danger of collision. VCASS can drastically reduce the potential accidents of vehicular collisions. However, VCASS can not avoid collisions between vehicles and pedestrians, but avoid collisions just between vehicles. About 30% of fatal accidents by vehicles are happened with pedestrians in Japan. So it is necessary to develop a new system for pedestrians. This paper deals with collision avoidance between pedestrians and vehicles. There are two problems to develop such system. First it is necessary to reduce the power consumption of the pedestrian terminal, because pedestrian terminals have small-sized battery compared with vehicles. Second it is necessary to consider the movement characteristic of the pedestrian. In this paper, we propose a new Pedestrian-Vehicular Collision Avoidance Support System (P-VCASS) which extends VCASS. P-VCASS solves above two problems. We show the validity of the proposed system by experiments using some vehicles.

  10. Hydrodynamic evolution and jet energy loss in Cu + Cu collisions

    SciTech Connect

    Schenke, Bjoern; Jeon, Sangyong; Gale, Charles

    2011-04-15

    We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.

  11. Turbulent collision statistics of cloud droplets at low dissipation rates

    NASA Astrophysics Data System (ADS)

    Banerjee, Sandipan

    Collisions of sedimenting droplets in a turbulent flow is of great importance in cloud physics. Collision efficiency and collision enhancement over gravitational collision by air turbulence govern the growth of the cloud droplets leading to warm rain initiation and precipitation dynamics. In this thesis we present direct numerical simulation (DNS) results for collision statistics of droplets in turbulent flows of low dissipation rates (in the range of 3 cm2/s3-100 cm2/s3) relevant to strato-cumulus clouds. First, we revisit the case of gravitational collision in still fluid to validate the details of the collision detection algorithm used in our code. We compare the collision statistics with either new analytical predictions regarding the percentages of different collision types, or results from published papers. The effect of initial conditions on the collision statistics and statistical uncertainties are analyzed both analytically and through the simulation data. Second, we consider the case of weak turbulence (as in strato-cumulus clouds). In this case the particle motion is mainly driven by gravity. The standard deviation (or the uncertainty) of the average collision statistics is examined analytically in terms of time correlation function of the data. We then report new DNS results of collision statistics in a turbulent flow, showing how air turbulence increases the geometric colli- sion statistics and the collision efficiency. We find that the collision-rate enhancement due to turbulence depends nonlinearly on the flow dissipation rate. This result calls for a more careful parameterization of the collision statistics in strato-cumulus clouds. Due to the low flow dissipation rate in stratocumulus clouds, a related challenge is low droplet Stokes number. Here the Stokes number is the ratio of droplet inertial response time to the flow Kolmogorov time. A very low Stokes number implies that the numerical integration time step is now governed by the droplet

  12. Exchange effects and collision mechanisms in (e, 2e) processes

    NASA Astrophysics Data System (ADS)

    Zhang-jin, Chen; Zhi-xiang, Ni; Qi-cun, Shi; Ke-zun, Xu

    1998-07-01

    In this work the triple differential cross sections for electron impact ionization of helium at an incident energy of 64.6 eV is considered in the coplanar symmetric energy-sharing and fixed relative angles of the two out-going electrons kinematics. A new collision process called triple-binary collision is identified. It has been shown that the ordinary double-binary collision process is excluded from the collision kinematics considered here. It has also been shown how the exchange effects symmetrically contribute to the peaks in the cross sections.

  13. A new technique for predicting geosynchronous satellite collision probability

    NASA Technical Reports Server (NTRS)

    Mccormick, B.

    1986-01-01

    A new technique has been developed to predict the probability of an expired geosynchronous satellite colliding with an active satellite. This new technique employs deterministic methods for modeling the motion of satellites and applies statistical techniques to estimate the collision probability. The collision probability is used to estimate the expected time between collisions based on realistic distributions of expired and active satellites. The primary advantage of this new technique is that realistic distributions can be used in the prediction process instead of uniform distributions as has been used in previous techniques. The expected time between collisions based on a current NORAD database is estimated to be in the hundreds of years.

  14. Scientists Track Collision of Powerful Stellar Winds

    NASA Astrophysics Data System (ADS)

    2005-04-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have tracked the motion of a violent region where the powerful winds of two giant stars slam into each other. The collision region moves as the stars, part of a binary pair, orbit each other, and the precise measurement of its motion was the key to unlocking vital new information about the stars and their winds. WR 140 Image Sequence Motion of Wind Collision Region Graphic superimposes VLBA images of wind collision region on diagram of orbit of Wolf-Rayet (WR) star and its giant (O) companion. Click on image for larger version (412K) CREDIT: Dougherty et al., NRAO/AUI/NSF In Motion: Shockwave File Animated Gif File AVI file Both stars are much more massive than the Sun -- one about 20 times the mass of the Sun and the other about 50 times the Sun's mass. The 20-solar-mass star is a type called a Wolf-Rayet star, characterized by a very strong wind of particles propelled outward from its surface. The more massive star also has a strong outward wind, but one less intense than that of the Wolf-Rayet star. The two stars, part of a system named WR 140, circle each other in an elliptical orbit roughly the size of our Solar System. "The spectacular feature of this system is the region where the stars' winds collide, producing bright radio emission. We have been able to track this collision region as it moves with the orbits of the stars," said Sean Dougherty, an astronomer at the Herzberg Institute for Astrophysics in Canada. Dougherty and his colleagues presented their findings in the April 10 edition of the Astrophysical Journal. The supersharp radio "vision" of the continent-wide VLBA allowed the scientists to measure the motion of the wind collision region and then to determine the details of the stars' orbits and an accurate distance to the system. "Our new calculations of the orbital details and the distance are vitally important to understanding the nature of these

  15. Liquid/liquid/solid contact angles

    NASA Astrophysics Data System (ADS)

    Borocco, Marine; Pellet, Charlotte; Authelin, Jean-René; Clanet, Christophe; Quéré, David; Compagnie des Interfaces Team

    2016-11-01

    Many studies have investigated solid/liquid/air interfaces and their corresponding wetting properties. We discuss what happens in less-studied liquid/liquid/solid systems, and focus on questions of dynamical wetting in a tube, having in mind applications in detergency. We use a capillary tube filled with water and containing a slug of silicone oil (or vice-versa), and present a series of experiments to determine static and dynamic wetting properties corresponding to this situation. We also discuss interfacial aging of such systems.

  16. Propagation of a liquid-liquid explosion

    SciTech Connect

    Harlow, F.H.; Ruppel, H.M.

    1981-08-01

    Direct contact between two liquids, one cold and the other hot, may be precluded by the presence of a vapor film. Bridging of this film by one or both fluids results in rapid local boiling, which may initiate a propagating liquid-liquid explosion. A mechanism is discussed for the propagation that involves implosion of the film, rapid mixing of the fluids, heat exchange to warm the cold fluid above the temperature for spontaneous nucleation, and the explosive generation of vapor, which in turn continues to sustain the film implosion. Plausibility for the model is demonstrated by means of numerical studies by high-speed computer.

  17. Radiation monitor for liquids

    DOEpatents

    Koster, James E.; Bolton, Richard D.

    1999-01-01

    A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans.

  18. Radiation monitor for liquids

    DOEpatents

    Koster, J.E.; Bolton, R.D.

    1999-03-02

    A radiation monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans. 4 figs.

  19. Collision-induced stimulated photon echo at the transition 0-1 in ytterbium: application to depolarizing collisions

    NASA Astrophysics Data System (ADS)

    Rubtsova, N. N.; Gol'dort, V. G.; Khvorostov, E. B.; Kochubei, S. A.; Reshetov, V. A.

    2017-02-01

    A new idea based on the collision-induced stimulated photon echo in the presence of weak longitudinal magnetic field is applied to the depolarizing collisions research in a gaseous mixture of ytterbium vapour with xenon. Comparison of experimental data with theoretical prediction for the collision-induced stimulated photon echo in the weak magnetic field shows that the alignment decay rate of state 3P1 in 174Yb is higher than the orientation decay rate.

  20. Liquid Wall Chambers

    SciTech Connect

    Meier, W R

    2011-02-24

    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

  1. Sliding Luttinger liquid phases

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Ranjan; Kane, C. L.; Lubensky, T. C.

    2001-07-01

    We study systems of coupled spin-gapped and gapless Luttinger liquids. First, we establish the existence of a sliding Luttinger liquid phase for a system of weakly coupled parallel quantum wires, with and without disorder. It is shown that the coupling can stabilize a Luttinger liquid phase in the presence of disorder. We then extend our analysis to a system of crossed Luttinger liquids and establish the stability of a non-Fermi-liquid state: the crossed sliding Luttinger liquid phase. In this phase the system exhibits a finite-temperature, long-wavelength, isotropic electric conductivity that diverges as a power law in temperature T as T-->0. This two-dimensional system has many properties of a true isotropic Luttinger liquid, though at zero temperature it becomes anisotropic. An extension of this model to a three-dimensional stack exhibits a much higher in-plane conductivity than the conductivity in a perpendicular direction.

  2. Liquid Propellant Manipulated Acoustically

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.; Chato, David J.; Mann, Adin, III

    2003-01-01

    Fluids are difficult to manage in the space environment. Without gravity, the liquid and gas do not always remain separated as they do in the 1g environment of Earth. Instead the liquid and gas volumes mix and migrate under the influence of surface tension, thermodynamic forces, and external disturbances. As a result, liquid propellants may not be in a useable location or may even form a chaotic mix of liquid and gas bubbles. In the past, mechanical pumps, baffles, and a variety of specialized passive devices have been used to control the liquid and gas volumes. These methods need to be carefully tuned to a specific configuration to be effective. With increasing emphasis on long-term human activity in space there is a trend toward liquid systems that are more flexible and provide greater control. We are exploring new methods of manipulating liquids by using the nonlinear acoustic effects achieved by using beams of highly directed high-intensity acoustic waves.

  3. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition.

  4. Origin of abnormally sharp features in collision-induced spectra of cryosolutions.

    PubMed

    Herrebout, W A; van der Veken, B J; Kouzov, A P; Filippov, N N

    2015-07-28

    A weak, paradoxically narrow resonance feature (shortly, the r-line) near the O2 fundamental frequency in the collision-induced absorption spectrum of oxygen dissolved in liquid argon and liquid nitrogen (T = 89 K) is resolved for the first time. An accurate band shape fitting routine to separate the r-line from the by-far more intense diffuse background and to study its behavior versus the oxygen mole fraction x which ranged from 0.03 up to 0.23 has been elaborated. At small x (≲0.07), the r-line intensity was found to scale as x(2) leaving no doubt that it is due to the solute-solute (O2-O2) interactions. In line with our results on the pH2-LNe cryosystem [Herrebout, Phys. Rev. Lett. 101, 093001 (2008)], the Lorentzian r-line shape and its extraordinary sharpness (half width at half height ≈ 1 cm(-1)) are indicative of the motional narrowing of the relative solute-solute translational spectrum. As x is further raised, ternary solute-solute interactions impede the r-line growth in the O2-LAr spectrum because of the cancellation effect [J. Van Kranendonk, Physica 23, 825 (1957)]. Theoretical arguments are given that multiple interactions between the solutes should finally destroy the solute-solute induced r-line when the mixed solution approaches the limit of the pure liquid (x = 1). Interestingly, the nonbinary effects are too weak to appreciably affect the quadratic r-line scaling in the O2-LN2 cryosystem which persists up to x = 0.23. It is emphasized that studies of the resonant features in the collision-induced spectra of binary cryosolutions open up unique opportunities to spectroscopically trace the microscopic-scale diffusion.

  5. Origin of abnormally sharp features in collision-induced spectra of cryosolutions

    NASA Astrophysics Data System (ADS)

    Herrebout, W. A.; van der Veken, B. J.; Kouzov, A. P.; Filippov, N. N.

    2015-07-01

    A weak, paradoxically narrow resonance feature (shortly, the r-line) near the O2 fundamental frequency in the collision-induced absorption spectrum of oxygen dissolved in liquid argon and liquid nitrogen (T = 89 K) is resolved for the first time. An accurate band shape fitting routine to separate the r-line from the by-far more intense diffuse background and to study its behavior versus the oxygen mole fraction x which ranged from 0.03 up to 0.23 has been elaborated. At small x (≲0.07), the r-line intensity was found to scale as x2 leaving no doubt that it is due to the solute-solute (O2-O2) interactions. In line with our results on the pH2-LNe cryosystem [Herrebout, Phys. Rev. Lett. 101, 093001 (2008)], the Lorentzian r-line shape and its extraordinary sharpness (half width at half height ≈ 1 cm-1) are indicative of the motional narrowing of the relative solute-solute translational spectrum. As x is further raised, ternary solute-solute interactions impede the r-line growth in the O2-LAr spectrum because of the cancellation effect [J. Van Kranendonk, Physica 23, 825 (1957)]. Theoretical arguments are given that multiple interactions between the solutes should finally destroy the solute-solute induced r-line when the mixed solution approaches the limit of the pure liquid (x = 1). Interestingly, the nonbinary effects are too weak to appreciably affect the quadratic r-line scaling in the O2-LN2 cryosystem which persists up to x = 0.23. It is emphasized that studies of the resonant features in the collision-induced spectra of binary cryosolutions open up unique opportunities to spectroscopically trace the microscopic-scale diffusion.

  6. Binary Collision Density in a Non-Ideal Gas as a Function of Particle Density, Collision Diameter, and Temperature

    NASA Astrophysics Data System (ADS)

    Mohazzabi, Pirooz

    2017-09-01

    Using molecular dynamics simulations, binary collision density in a dense non-ideal gas with Lennard-Jones interactions is investigated. It is shown that the functional form of the dependence of collision density on particle density and collision diameter remains the same as that for an ideal gas. The temperature dependence of the collision density, however, has a very different form at low temperatures, where it decreases as temperature increases. But at higher temperatures the functional form becomes the same as that for an ideal gas.

  7. Radiative Association in Li+ + H- collisions

    NASA Astrophysics Data System (ADS)

    Dickinson, A. S.; Gadéa, F. X.

    Radiative association is one of the ways of forming LiH in low density environments. Its formation in collisions of Li(2p) +H(1s) has been shown to be about five orders of magnitude faster than for Li(2s) + H(1s) [1]. We investigate LiH formation in Li+ + H- collisions, considering association on both the C and D Σ states as about 96% of the mutual neutralization is to these states at low energy [2]. A quantal description of the process [3] has been used. The potentials are from ref. [4] and the dipole moments from ref. [5]. Similar results were obtained from both the C and D states. At 1000 K the total radiative association rate coefficient from the D state is 9.2× 10-15 cm3/s, compared to 2.1 × 10-20 cm3/s in Li(2s) + H(1s) collisions [6]. British Council support is gratefully acknowledged. {[1]} Gianturco F.A., Gori Giorgi P., 1996, Phys. Rev. A 54, 4073 {[2]} Croft H., Dickinson A.S., Gadéa F. X., 1999, MNRAS 304, 327 {[3]} Babb J.F., Kirby K.P., 1998, in The Molecular Astrophysics of Stars and Galaxies, Clarendon Press, Oxford, p. 11 {[4]} Gadéa F. X., Boutalib A., 1993, J. Phys. B 26, 61 {[5]} Berriche H., Gadéa F. X., 1995, Chem. Phys. Letts. 247 85 {[6]} Stancil P. C., Dalgarno A., 1997, ApJ 479, 543

  8. Exposure assessment in auto collision repair shops.

    PubMed

    Bejan, Anca; Brosseau, Lisa M; Parker, David L

    2011-07-01

    Workers in auto collision shops are exposed to a variety of chemical and physical hazards. Previous studies have focused on measuring levels of isocyanates, but little is known about exposures to dust, noise, and solvents. In preparation for an intervention effectiveness study in small collision repair businesses, sampling was conducted on 3 consecutive days in four representative businesses with three to seven employees. Full-shift and task-specific exposures were measured for dust and solvents (for operations other than painting and spray gun cleaning). Full-shift personal exposures and tool-specific noise levels were also evaluated. Samples of banded earplugs were distributed to employees and feedback was collected after 1 week of wear time. Dust and solvent exposures did not exceed the OSHA PELs. Noise exposure doses were below the OSHA PEL; however, 4 of the 18 measurements were in excess of the ACGIH® threshold limit value. The majority of tools generated noise levels above 85 dBA. Air guns, wrenches, cutoff wheels, and air drills generated noise levels with the 5th percentile above 90 dBA. Mean noise levels generated by hammers, grinders, and ratchets were also above 95 dBA. Three pairs of banded earplugs had the best reviews in terms of comfort of use. This study was conducted during a time when all shops reported relatively low production levels. Noise exposure results suggest that it is likely that technicians' 8-hr time-weighted average exposures may be in excess of 85 dBA during periods of higher production, but exposures to dust and solvents are unlikely to approach OSHA exposure limits. These pilot test results will be useful when developing recommendations and technical assistance materials for health and safety interventions in auto collision repair businesses.

  9. Collision-geometry fluctuations and triangular flow in heavy-ion collisions

    SciTech Connect

    Alver, B.; Roland, G.

    2010-05-15

    We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multiphase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  10. Influence of pre-collision occupant parameters on injury outcome in a frontal collision.

    PubMed

    Bose, D; Crandall, J R; Untaroiu, C D; Maslen, E H

    2010-07-01

    Optimal performance of adaptive restraint systems in the vehicle requires an accurate assessment of occupant characteristics including physical properties and pre-collision response of the occupant. To provide a feasible framework for incorporating occupant characteristics into adaptive restraint schemes, this study evaluates the sensitivity of injury risk in frontal collisions to four occupant parameters: mass, stature, posture and bracing level. The numerical approach includes using commercial multi-body software to develop occupant models that span a range of occupant parameters representative of the real-world driver population. Coupled with a multi-body model of the vehicle interior and standard restraint system, risk of occupant injuries within specific body regions are predicted through numerical simulations in conjunction with established injury risk functions. The results show occupant posture to be the most significant parameter affecting the overall risk of injury in frontal collisions. The causal relationship as predicted using the numerical model has been compared to the traffic injury epidemiology findings, and the feasibility of an analytical methodology to provide real-time estimates of injury severity has been discussed. Preliminary estimates from the study indicate that the proposed methodology will provide a framework to optimize restraint performance and potentially reduce the risk of injuries up to 35% (based on parameter-specific optimization), using accurate information regarding the pre-collision occupant characteristics. Copyright 2010 Elsevier Ltd. All rights reserved.

  11. High energy hadron-hadron collisions. [Dept. of Physics and Astronomy, Univ. of Georgia, Athens, Georgia

    SciTech Connect

    Chou, T.T.

    1992-01-01

    Results of a study on high energy collisions with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) e[sup +]e[sup [minus

  12. Physics of Nuclear Collisions at High Energy

    SciTech Connect

    Hwa, Rudolph C.

    2012-05-01

    A wide range of problems has been investigated in the research program during the period of this grant. Although the major effort has been in the subject of heavy-ion collisions, we have also studied problems in biological and other physical systems. The method of analysis used in reducing complex data in multiparticle production to simple descriptions can also be applied to the study of complex systems of very different nature. Phase transition is an important phenomenon in many areas of physics, and for heavy-ion collisions we study the fluctuations of multiplicities at the critical point. Human brain activities as revealed in EEG also involve fluctuations in time series, and we have found that our experience enables us to find the appropriate quantification of the fluctuations in ways that can differentiate stroke and normal subjects. The main topic that characterizes the research at Oregon in heavy-ion collisions is the recombination model for the treatment of the hadronization process. We have avoided the hydrodynamical model partly because there is already a large community engaged in it, but more significantly we have found the assumption of rapid thermalization unconvincing. Recent results in studying LHC physics lead us to provide more evidence that shower partons are very important even at low p_T, but are ignored by hydro. It is not easy to work in an environment where the conventional wisdom regards our approach as being incorrect because it does not adhere to the standard paradigm. But that is just what a vibrant research community needs: unconventional approach may find evidences that can challenge the orthodoxy. An example is the usual belief that elliptic flow in fluid dynamics gives rise to azimuthal anisotropy. We claim that it is only sufficient but not necessary. With more data from LHC and more independent thinkers working on the subject what is sufficient as a theory may turn out to be incorrect in reality. Another area of investigation that

  13. Two-Dimensional Distributed Velocity Collision Avoidance

    DTIC Science & Technology

    2014-02-11

    trigonometry . For convex polygon agents, the tangents are found by iterating over each point, calculating the z-component of the cross product between a...the modifications to the basic VO to favor the source bot’s current velocity (i.e., encourage the bot to change course as little as possible). To...the source agent on a collision course . However, if ignore factors are used, then A2 is more important (i.e., has a lower ignore factor), and so the

  14. Global Λ polarization in high energy collisions

    NASA Astrophysics Data System (ADS)

    Xie, Yilong; Wang, Dujuan; Csernai, László P.

    2017-03-01

    With a Yang-Mills flux-tube initial state and a high-resolution (3+1)D particle-in-cell relativistic (PICR) hydrodynamics simulation, we calculate the Λ polarization for different energies. The origination of polarization in high energy collisions is discussed, and we find linear impact parameter dependence of the global Λ polarization. Furthermore, the global Λ polarization in our model decreases very quickly in the low energy domain, and the decline curve fits well the recent results of Beam Energy Scan (BES) program launched by the STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC). The time evolution of polarization is also discussed.

  15. RHIC operation with asymmetric collisions in 2015

    SciTech Connect

    Liu, C.; Aschenauer, C.; Atoian, G.; Blaskiewicz, M.; Brown, K. A.; Bruno, D.; Connolly, R.; Ottavio, T. D.; Drees, K. A.; Fischer, W.; Gardner, C. J.; Gu, X.; Hayes, T.; Huang, H.; Laster, J. S.; Luo, Y.; Makdisi, Y.; Marr, G.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Morris, J.; Narayan, G.; Nayak, S.; Nemesure, S.; Pile, P.; Poblaguev, A.; Ranjbar, V.; Robert-Demolaize, G.; Roser, T.; Schmidke, B.; Schoefer, V.; Severino, F.; Shrey, T.; Smith, K.; Steski, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Wang, G.; White, S.; Yip, K.; Zaltsman, A.; Zeno, K.; Zhang, S. Y.

    2015-08-07

    To study low-x shadowing/saturation physics as well as other nuclear effects [1], [2], proton-gold (p-Au, for 5 weeks) and proton-Aluminum (p-Al, for 2 weeks) collisions were provided for experiments in 2015 at the Relativistic Heavy Ion Collider (RHIC), with polarized proton beam in the Blue ring and Au/Al beam in the Yellow ring. The special features of the asymmetric run in 2015 will be introduced. The operation experience will be reviewed as well in the report.

  16. Leading neutrons from polarized pp collisions

    SciTech Connect

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Soffer, J.

    2008-10-13

    We calculate the cross section and single-spin azimuthal asymmetry, A{sub n}(t) for inclusive neutron production in pp collisions at forward rapidities relative to the polarized proton. Absorptive corrections to the pion pole generate a relative phase between the spin-flip and non-flip amplitudes, which leads to an appreciable spin asymmetry. However, the asymmetry observed recently in the PHENIX experiment at RHIC at very small |t|{approx}0.01 GeV{sup 2} cannot be explained by this mechanism.

  17. Dynamical phase trajectories for relativistic nuclear collisions

    SciTech Connect

    Arsene, I. C.; Bravina, L. V.; Cassing, W.; Ivanov, Yu. B.; Russkikh, V. N.; Larionov, A.; Randrup, J.; Toneev, V. D.; Zeeb, G.; Zschiesche, D.

    2007-03-15

    Central collisions of gold nuclei are simulated by several existing models and the central net baryon density {rho} and the energy density {epsilon} are extracted at successive times for beam kinetic energies of 5-40 GeV/nucleon. The resulting trajectories in the ({rho},{epsilon}) phase plane are discussed from the perspective of experimentally exploring the expected first-order hadronization phase transition with the planned FAIR at GSI or in a low-energy campaign at the Relativistic Heavy Ion Collider.

  18. Multiverse rate equation including bubble collisions

    NASA Astrophysics Data System (ADS)

    Salem, Michael P.

    2013-03-01

    The volume fractions of vacua in an eternally inflating multiverse are described by a coarse-grain rate equation, which accounts for volume expansion and vacuum transitions via bubble formation. We generalize the rate equation to account for bubble collisions, including the possibility of classical transitions. Classical transitions can modify the details of the hierarchical structure among the volume fractions, with potential implications for the staggering and Boltzmann-brain issues. Whether or not our vacuum is likely to have been established by a classical transition depends on the detailed relationships among transition rates in the landscape.

  19. Jets In Heavy Ion Collisions with CMS

    NASA Astrophysics Data System (ADS)

    Salur, Sevil

    2016-08-01

    Jet physics in heavy ion collisions is a rich field which has been rapidly evolving since the first observations of medium interactions at RHIC through back-to-back hadron correlations and at LHC via reconstructed jets. In order to completely characterize the final state via jet-medium interactions and distinguish between competing energy loss mechanisms, complementary and robust jet observables are investigated. Latest developments of jet finding techniques and their applications to heavy ion environments are discussed with an emphasis given on experimental results from CMS experiment.

  20. Action principle for Coulomb collisions in plasmas

    NASA Astrophysics Data System (ADS)

    Hirvijoki, Eero

    2016-09-01

    An action principle for Coulomb collisions in plasmas is proposed. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth-MacDonald-Judd potentials. Conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles.