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Sample records for binary collision approximation

  1. Comparison of binary collision approximation and molecular dynamics for displacement cascades in GaAs.

    SciTech Connect

    Foiles, Stephen Martin

    2011-10-01

    The predictions of binary collision approximation (BCA) and molecular dynamics (MD) simulations of displacement cascades in GaAs are compared. There are three issues addressed in this work. The first is the optimal choice of the effective displacement threshold to use in the BCA calculations to obtain the best agreement with MD results. Second, the spatial correlations of point defects are compared. This is related to the level of clustering that occurs for different types of radiation. Finally, the size and structure of amorphous zones seen in the MD simulations is summarized. BCA simulations are not able to predict the formation of amorphous material.

  2. Extension of Binary-Collision-Approximation-Based Simulation Applicable to Any Structured Target Material

    NASA Astrophysics Data System (ADS)

    Takayama, Arimichi; Saito, Seiki; Ito, Atsushi M.; Kenmotsu, Takahiro; Nakamura, Hiroaki

    2011-01-01

    We have investigated plasma-surface interactions by performing molecular dynamics (MD) simulations. However, such simulations have a high computation cost and are limited to simulations of materials of nanometer order. In order to overcome this limitation, a complementary model based on the binary collision approximation (BCA) can be established. We employed the BCA-based simulation code ACAT and extended it to handle any crystalline or amorphous structure. The extended code, named “AC∀T”, stores the positions of all projectile and target atoms and the velocities of recoil atoms so that it can be combined with the MD code. It also has the potential to reproduce channeling phenomena. Thus, it is expected to be useful for the evaluation of channeling effects.

  3. Determination of recombination radius in Si for binary collision approximation codes

    SciTech Connect

    Vizkelethy, Gyorgy; Foiles, Stephen M.

    2015-09-11

    Displacement damage caused by ions or neutrons in microelectronic devices can have significant effect on the performance of these devices. Therefore, it is important to predict not only the displacement damage profile, but also its magnitude precisely. Analytical methods and binary collision approximation codes working with amorphous targets use the concept of displacement energy, the energy that a lattice atom has to receive to create a permanent replacement. It was found that this “displacement energy” is direction dependent; it can range from 12 to 32 eV in silicon. Obviously, this model fails in BCA codes that work with crystalline targets, such as Marlowe. Marlowe does not use displacement energy; instead, it uses lattice binding energy only and then pairs the interstitial atoms with vacancies. Then based on the configuration of the Frenkel pairs it classifies them as close, near, or distant pairs, and considers the distant pairs the permanent replacements. Unfortunately, this separation is an ad hoc assumption, and the results do not agree with molecular dynamics calculations. After irradiation, there is a prompt recombination of interstitials and vacancies if they are nearby, within a recombination radius. In order to implement this recombination radius in Marlowe, we used the comparison of MD and Marlowe calculation in a range of ion energies in single crystal silicon target. As a result, the calculations showed that a single recombination radius of ~7.4 Å in Marlowe for a range of ion energies gives an excellent agreement with MD.

  4. Determination of recombination radius in Si for binary collision approximation codes

    DOE PAGES

    Vizkelethy, Gyorgy; Foiles, Stephen M.

    2015-09-11

    Displacement damage caused by ions or neutrons in microelectronic devices can have significant effect on the performance of these devices. Therefore, it is important to predict not only the displacement damage profile, but also its magnitude precisely. Analytical methods and binary collision approximation codes working with amorphous targets use the concept of displacement energy, the energy that a lattice atom has to receive to create a permanent replacement. It was found that this “displacement energy” is direction dependent; it can range from 12 to 32 eV in silicon. Obviously, this model fails in BCA codes that work with crystalline targets,more » such as Marlowe. Marlowe does not use displacement energy; instead, it uses lattice binding energy only and then pairs the interstitial atoms with vacancies. Then based on the configuration of the Frenkel pairs it classifies them as close, near, or distant pairs, and considers the distant pairs the permanent replacements. Unfortunately, this separation is an ad hoc assumption, and the results do not agree with molecular dynamics calculations. After irradiation, there is a prompt recombination of interstitials and vacancies if they are nearby, within a recombination radius. In order to implement this recombination radius in Marlowe, we used the comparison of MD and Marlowe calculation in a range of ion energies in single crystal silicon target. As a result, the calculations showed that a single recombination radius of ~7.4 Å in Marlowe for a range of ion energies gives an excellent agreement with MD.« less

  5. Study of the fragmentation of a displacement cascade in subcascades within the Binary Collision Approximation framework

    SciTech Connect

    Luneville, Laurence; Simone, David; Weber, William J

    2011-01-01

    When a material is subjected to irradiation, many primary defects are cre- ated at the atomic level by sequences of ballistic collision events to form highly disordered regions defined as displacement cascades. The long term evolution of materials under irradiation is dictated by the number and the spatial distribution of the surviving defects in the displacement cascade. The peculiar power law shape of collision cross sections is responsible for the frag- mentation of a displacement cascade into smaller subcascades. However, it remains difficult to define a subcascade. Within the fractal geometry frame- work, we demonstrate in this work that the set of atomic trajectories in a displacement cascade exhibit a fractal behavior. From this analysis, we present a new criterion to describe the fragmentation of a displacement cas- cade and to calculate the distribution and the number of defects from this fragmentation. Such an analysis provides the natural framework to estimate the number of defects created in a displacement cascade to integrate with results of MD simulations. From this defiintion of the fragmentation of a displacement cascade, this work gives some new insights to describe both the primary defects produced in a material under irradiation and then to compare different irradiations performed with different particles.

  6. Multiscale Coupling of Monte Carlo Binary-Collision-Approximation Codes with Particle-in-Cells for Plasma-Material Interaction

    NASA Astrophysics Data System (ADS)

    Curreli, Davide; Lindquist, Kyle; Ruzic, David N.

    2013-10-01

    Techniques based on Monte Carlo Binary Collision Approximation (BCA) are widely used for the evaluation of particle interactions with matter, but rarely coupled with a consistent kinetic plasma solver like a Particle-in-Cell. The TRIM code [Eckstein; Biersack and Haggmark, 1980] and its version including dynamic-composition TRIDYN [Moller and Eckstein, 1984] are two popular implementations of BCA, where single-particle projectiles interact with a target of amorphous material according to the classical Carbon-Krypton interaction potential. The effect of surface roughness can be included as well, thanks to the Fractal-TRIM method [Ruzic and Chiu, 1989]. In the present study we couple BCA codes with Particles-in-Cells. The Lagrangian treatment of particle motion usually implemented in PiC codes suggests a natural coupling of PiC's with BCA's, even if a number of caveats has to be taken into account, related to the discrete nature of computational particles, to the difference between the two approaches and most important to the multiple spatial and temporal scales involved. The break down of BCA at low energies (unless the projectiles are channeling through an oriented crystal layer [Hobler and Betz, 2001]) has been supplemented by Yamamura's semi-empirical relations.

  7. Primary damage in tungsten using the binary collision approximation, molecular dynamic simulations and the density functional theory

    NASA Astrophysics Data System (ADS)

    De Backer, A.; Sand, A.; Ortiz, C. J.; Domain, C.; Olsson, P.; Berthod, E.; Becquart, C. S.

    2016-02-01

    The damage produced by primary knock-on atoms (PKA) in W has been investigated from the threshold displacement energy (TDE) where it produces one self interstitial atom-vacancy pair to larger energies, up to 100 keV, where a large molten volume is formed. The TDE has been determined in different crystal directions using the Born-Oppenheimer density functional molecular dynamics (DFT-MD). A significant difference has been observed without and with the semi-core electrons. Classical MD has been used with two different empirical potentials characterized as ‘soft’ and ‘hard’ to obtain statistics on TDEs. Cascades of larger energy have been calculated, with these potentials, using a model that accounts for electronic losses (Sand et al 2013 Europhys. Lett. 103 46003). Two other sets of cascades have been produced using the binary collision approximation (BCA): a Monte Carlo BCA using SDTrimSP (Eckstein et al 2011 SDTrimSP: Version 5.00. Report IPP 12/8) (similar to SRIM www.srim.org) and MARLOWE (RSICC Home Page. (https://rsicc.ornl.gov/codes/psr/psr1/psr-137.html) (accessed May, 2014)). The comparison of these sets of cascades gave a recombination distance equal to 12 Å which is significantly larger from the one we reported in Hou et al (2010 J. Nucl. Mater. 403 89) because, here, we used bulk cascades rather than surface cascades which produce more defects (Stoller 2002 J. Nucl. Mater. 307 935, Nordlund et al 1999 Nature 398 49). Investigations on the defect clustering aspect showed that the difference between BCA and MD cascades is considerably reduced after the annealing of the cascade debris at 473 K using our Object Kinetic Monte Carlo model, LAKIMOCA (Domain et al 2004 J. Nucl. Mater. 335 121).

  8. 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).

  9. Evaluation of interatomic potentials for noble gas atoms from rainbow scattering under axial channeling at Ag(1 1 1) surface by computer simulations based on binary collision approximation

    NASA Astrophysics Data System (ADS)

    Takeuchi, Wataru

    2016-01-01

    The rainbow angles corresponding to pronounced peaks in the angular distributions of scattered projectiles with small angle, attributed to rainbow scattering (RS), under axial surface channeling conditions are strongly dependent on the interatomic potentials between projectiles and target atoms. The dependence of rainbow angles on normal energy of projectile energy to the target surface that has been experimentally obtained by Schüller and Winter (SW) (2007) for RS of He, Ne and Ar atoms from a Ag(1 1 1) surface with projectile energies of 3-60 keV was evaluated by the three-dimensional computer simulations using the ACOCT code based on the binary collision approximation with interatomic pair potentials. Consequently, the ACOCT results employing the Moliere pair potential with screening length correction close to adjustable one of O'Connor and Biersack (OB) formula are almost in agreement with the experimental ones, being self-consistent with the SW's ones analyzed by computer simulations of classical trajectory calculations as RS from corrugated equipotential planes based on continuum potentials including the Moliere pair potential with screening length correction of the OB formula.

  10. 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.

  11. Solitary waves in dimer binary collision model

    NASA Astrophysics Data System (ADS)

    Ahsan, Zaid; Jayaprakash, K. R.

    2017-01-01

    Solitary wave propagation in nonlinear diatomic (dimer) chains is a very interesting topic of research in the study of nonlinear lattices. Such waves were recently found to be supported by the essentially nonlinear granular lattice and Toda lattice. An interesting aspect of this discovery is attributed to the realization of a spectrum of the mass ratio (the only system parameter governing the dynamics) that supports the propagation of such waves corresponding to the considered interaction potential. The objective of this exposition is to explore solitary wave propagation in the dimer binary collision (BC) model. Interestingly, the dimer BC model supports solitary wave propagation at a discrete spectrum of mass ratios similar to those observed in granular and Toda dimers. Further, we report a qualitative and one-to-one correspondence between the spectrum of the mass ratio corresponding to the dimer BC model and those corresponding to granular and Toda dimer chains.

  12. Lifetime of binary asteroids versus gravitational encounters and collisions

    NASA Technical Reports Server (NTRS)

    Chauvineau, Bertrand; Farinella, Paolo; Mignard, F.

    1992-01-01

    We investigate the effect on the dynamics of a binary asteroid in the case of a near encounter with a third body. The dynamics of the binary is modeled as a two-body problem perturbed by an approaching body in the following ways: near encounters and collisions with a component of the system. In each case, the typical value of the two-body energy variation is estimated, and a random walk for the cumulative effect is assumed. Results are applied to some binary asteroid candidates. The main conclusion is that the collisional disruption is the dominant effect, giving lifetimes comparable to or larger than the age of the solar system.

  13. Binary black hole evolutions of approximate puncture initial data

    SciTech Connect

    Bode, Tanja; Laguna, Pablo; Shoemaker, Deirdre M.; Hinder, Ian; Herrmann, Frank; Vaishnav, Birjoo

    2009-07-15

    Approximate solutions to the Einstein field equations are valuable tools to investigate gravitational phenomena. An important aspect of any approximation is to investigate and quantify its regime of validity. We present a study that evaluates the effects that approximate puncture initial data, based on skeleton solutions to the Einstein constraints as proposed by [G. Faye, P. Jaranowski, and G. Schaefer, Phys. Rev. D 69, 124029 (2004).], have on numerical evolutions. Using data analysis tools, we assess the effectiveness of these constraint-violating initial data for both initial and advanced LIGO and show that the matches of waveforms from skeleton data with the corresponding waveforms from constraint-satisfying initial data are > or approx. 0.97 when the total mass of the binary is > or approx. 40M{sub {center_dot}}. In addition, we demonstrate that the differences between the skeleton and the constraint-satisfying initial data evolutions, and thus waveforms, are due to negative Hamiltonian constraint violations present in the skeleton initial data located in the vicinity of the punctures. During the evolution, the skeleton data develops both Hamiltonian and momentum constraint violations that decay with time, with the binary system relaxing to a constraint-satisfying solution with black holes of smaller mass and thus different dynamics.

  14. Approximate universal relations among tidal parameters for neutron star binaries

    NASA Astrophysics Data System (ADS)

    Yagi, Kent; Yunes, Nicolás

    2017-01-01

    One of largest uncertainties in nuclear physics is the relation between the pressure and density of supranuclear matter: the equation of state. Some of this uncertainty may be removed through future gravitational wave observations of neutron star binaries by extracting the tidal deformabilities (or Love numbers) of neutron stars, a novel way to probe nuclear physics in the high-density regime. Previous studies have shown that only a certain combination of the individual (quadrupolar) deformabilities of each body (the so-called chirp tidal deformability) can be measured with second-generation, gravitational wave interferometers, such as Adv. LIGO, due to correlations between the individual deformabilities. To overcome this, we search for approximately universal (i.e. approximately equation-of-state independent) relations between two combinations of the individual tidal deformabilities, such that once one of them has been measured, the other can be automatically obtained and the individual ones decoupled through these relations. We find an approximately universal relation between the symmetric and the anti-symmetric combination of the individual tidal deformabilities that is equation-of-state-insensitive to 20 % for binaries with masses less than 1.7{{M}⊙} . We show that these relations can be used to eliminate a combination of the tidal parameters from the list of model parameters, thus breaking degeneracies and improving the accuracy in parameter estimation. A simple (Fisher) study shows that the universal binary Love relations can improve the accuracy in the extraction of the symmetric combination of tidal parameters by as much as an order of magnitude, making the overall accuracy in the extraction of this parameter slightly better than that of the chirp tidal deformability. These new universal relations and the improved measurement accuracy on tidal parameters not only are important to astrophysics and nuclear physics, but also impact our ability to probe

  15. Parameter estimates in binary black hole collisions using neural networks

    NASA Astrophysics Data System (ADS)

    Carrillo, M.; Gracia-Linares, M.; González, J. A.; Guzmán, F. S.

    2016-10-01

    We present an algorithm based on artificial neural networks (ANNs), that estimates the mass ratio in a binary black hole collision out of given gravitational wave (GW) strains. In this analysis, the ANN is trained with a sample of GW signals generated with numerical simulations. The effectiveness of the algorithm is evaluated with GWs generated also with simulations for given mass ratios unknown to the ANN. We measure the accuracy of the algorithm in the interpolation and extrapolation regimes. We present the results for noise free signals and signals contaminated with Gaussian noise, in order to foresee the dependence of the method accuracy in terms of the signal to noise ratio.

  16. Binary collision rates of relativistic thermal plasmas. I Theoretical framework

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.

    1985-01-01

    Binary collision rates for arbitrary scattering cross sections are derived in the case of a beam of particles interacting with a Maxwell-Boltzmann (MB) plasma, or in the case of two MB plasmas interacting at generally different temperatures. The expressions are valid for all beam energies and plasma temperatures, from the nonrelativistic to the extreme relativistic limits. The calculated quantities include the reaction rate, the energy exchange rate, and the average rate of change of the squared transverse momentum component of a monoenergetic particle beam as a result of scatterings with particles of a MB plasma. Results are specialized to elastic scattering processes, two-temperature reaction rates, or the cold plasma limit, reproducing previous work.

  17. A Hybrid Approximation Technique for Head-on Black-Hole-Binary Mergers

    NASA Astrophysics Data System (ADS)

    Nichols, David; Chen, Yanbei; Keppel, Drew; Lovelace, Geoffrey; Sperhake, Ulrich

    2010-02-01

    Black-hole-binary coalescence is often divided into three stages, inspiral, merger and ringdown; the post-Newtonian (PN) approximation treats the inspiral phase, black-hole perturbation (BHP) theory describes the ringdown, and the strongly nonlinear dynamics of spacetime characterize the merger. In this paper, we introduce a hybrid method that incorporates elements of PN and BHP theories, and we apply it to the head-on collision of black holes with transverse, anti-parallel spins. We compare our approximation technique with a full numerical-relativity simulation by G. Lovelace et al, and we find surprisingly good agreement between the gravitational waveforms and the radiated energy and momentum. We also apply this model to understand the flow of gravitational field momentum in the simulation, quantified by the Landau-Lifshitz pseudotensor. Our results indicate that while PN and BHP theories do not capture all the strongly nonlinear physics of the merger, they do suffice to explain the outgoing gravitational radiation for head-on mergers. )

  18. Very wide binary stars as the primary source of stellar collisions in the galaxy

    SciTech Connect

    Kaib, Nathan A.; Raymond, Sean N.

    2014-02-20

    We present numerical simulations modeling the orbital evolution of very wide binaries, pairs of stars separated by over ∼10{sup 3} AU. Due to perturbations from other passing stars and the Milky Way's tide, the orbits of very wide binary stars occasionally become extremely eccentric, which forces close encounters between the companion stars. We show that this process causes a stellar collision between very wide binary companion stars once every 1000-7500 yr on average in the Milky Way. One of the main uncertainties in this collision rate is the amount of energy dissipated by dynamic tides during close (but not collisional) periastron passages. This dissipation presents a dynamical barrier to stellar collisions and can instead transform very wide binaries into close or contact binaries. However, for any plausible tidal dissipation model, very wide binary stars are an unrealized, and potentially the dominant, source of stellar collisions in our Galaxy. Such collisions should occur throughout the thin disk of the Milky Way. Stellar collisions within very wide binaries should yield a small population of single, Li-depleted, rapidly rotating massive stars.

  19. Use of the Glauber approximation in atomic collisions - A progress report.

    NASA Technical Reports Server (NTRS)

    Gerjuoy, E.

    1972-01-01

    Recent progress in the use of the Glauber (1970) theory for estimating atomic collision cross sections is reviewed. It appears that the Glauber approximation is reliable for electron-hydrogen elastic scattering and excitation at incident energies exceeding 30 eV. For more complicated atomic collisions, the usefulness of the Glauber approximation has not yet been significantly tested.

  20. Simple model of surface roughness for binary collision sputtering simulations

    NASA Astrophysics Data System (ADS)

    Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

    2017-02-01

    It has been shown that surface roughness can strongly influence the sputtering yield - especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the "density gradient model") which imitates surface roughness effects. In the model, the target's atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient - leading to increased sputtering yields, similar in effect to surface roughness.

  1. Zero-degree binary encounter electrons in fast collisions of highly charged F and O ions with H 2 targets

    NASA Astrophysics Data System (ADS)

    Lee, D. H.; Zouros, T. J. M.; Sanders, J. M.; Hidmi, H.; Richard, P.

    1993-06-01

    Doubly differential cross sections (DDCS) for binary encounter electrons (BEe) produced by 0.5-2 MeV/u highly-charged F and O ions in collisions with H 2 gas targets have been studied at 0° with respect to the ion beam direction. The measured DDCS of the broad binary encounter peak was well described by a simple impulse approximation (IA) treatment for bare ions, and was demonstrated to provide in situ detection efficiency of the electron spectrometer. The projectile energy dependence of the BEe production for nonbare (clothed) projectiles is found to follow a scaled IA prediction, in which a BEe enhancement is consistently exhibited for the collision energy range studied.

  2. Binary and triple collisions causing instability in the free-fall three-body problem

    NASA Astrophysics Data System (ADS)

    Umehara, Hiroaki; Tanikawa, Kiyotaka

    2000-04-01

    Dominant factors for escape after the first triple-encounter are searched for in the three-body problem with zero initial velocities and equal masses. By a global numerical survey on the whole initial-value space, it is found that not only a triple-collision orbit but also a particular family of binary-collision orbits exist in the set of escape orbits. This observation is justified from various viewpoints. Binary-collision orbits experiencing close triple-encounter turn out to be close to isosceles orbits after the encounter and hence lead to escape. Except for a few cases, binary-collision orbits of near-isosceles slingshot also escape.

  3. Collisions of Halo Nuclei within a Dynamical Eikonal Approximation

    SciTech Connect

    Baye, D.; Goldstein, G.

    2005-08-19

    The dynamical eikonal approximation unifies the semiclassical time-dependent and eikonal methods. It allows calculating differential cross sections for elastic scattering and breakup in a quantal way by taking into account interference effects. Good agreement is obtained with experiment for {sup 11}Be breakup on {sup 208}Pb. Dynamical effects are weak for elastic scattering.

  4. Effect of Collision Angle on Binary Droplet Coalescence

    NASA Astrophysics Data System (ADS)

    Kim, Jungyong; Longmire, Ellen

    2006-11-01

    Drop pairs of water/glycerin solution were injected into silicone oil of lower density through opposing tubes at varying initial angles with the goal of controlling the eventual collision angles. Simultaneous dual-field PIV measurements were obtained in index-matched fluids to characterize coalescence and rebounding behavior. The larger field captured trajectories, and the smaller field captured the thin film region. Experiments were performed for Weber numbers [We] in the range of 1-50 and collision angles of 15-80 degrees below the horizontal. Above We ˜ 10, drops coalesced, with the rebounding/coalescence boundary shifting to higher We with increasing collision angle. Also, the collision angle affected the eventual location of film rupture. The rupture location moved higher in the thin film region as the collision angle increased. Interactions of vortex rings within drops and strong deformation associated with shallow collision angles and sufficient We encouraged coalescence. Details of these interactions will be discussed in the presentation. Supported by Petroleum Research Fund (42939-AC9) and NSF (CTS-0320327).

  5. Analysis of the Conformally Flat Approximation for Binary Neutron Star Initial Conditions

    NASA Astrophysics Data System (ADS)

    Suh, In-Saeng; Mathews, Grant J.; Haywood, J. Reese; Lan, N. Q.

    The spatially conformally flat approximation (CFA) is a viable method to deduce initial conditions for the subsequent evolution of binary neutron stars employing the full Einstein equations. Here we review the status of the original formulation of the CFA for the general relativistic hydrodynamic initial conditions of binary neutron stars. We illustrate the stability of the conformally flat condition on the hydrodynamics by numerically evolving ~100 quasi-circular orbits. We illustrate the use of this approximation for orbiting neutron stars in the quasi-circular orbit approximation to demonstrate the equation of state dependence of these initial conditions and how they might affect the emergent gravitational wave frequency as the stars approach the innermost stable circular orbit.

  6. Heats of Segregation of BCC Binaries from Ab Initio and Quantum Approximate Calculations

    NASA Technical Reports Server (NTRS)

    Good, Brian S.

    2003-01-01

    We compare dilute-limit segregation energies for selected BCC transition metal binaries computed using ab initio and quantum approximate energy methods. Ab initio calculations are carried out using the CASTEP plane-wave pseudopotential computer code, while quantum approximate results are computed using the Bozzolo-Ferrante-Smith (BFS) method with the most recent parameters. Quantum approximate segregation energies are computed with and without atomistic relaxation. Results are discussed within the context of segregation models driven by strain and bond-breaking effects. We compare our results with full-potential quantum calculations and with available experimental results.

  7. Heats of Segregation of BCC Binaries from ab Initio and Quantum Approximate Calculations

    NASA Technical Reports Server (NTRS)

    Good, Brian S.

    2004-01-01

    We compare dilute-limit heats of segregation for selected BCC transition metal binaries computed using ab initio and quantum approximate energy methods. Ab initio calculations are carried out using the CASTEP plane-wave pseudopotential computer code, while quantum approximate results are computed using the Bozzolo-Ferrante-Smith (BFS) method with the most recent LMTO-based parameters. Quantum approximate segregation energies are computed with and without atomistic relaxation, while the ab initio calculations are performed without relaxation. Results are discussed within the context of a segregation model driven by strain and bond-breaking effects. We compare our results with full-potential quantum calculations and with available experimental results.

  8. Surface Segregation Energies of BCC Binaries from Ab Initio and Quantum Approximate Calculations

    NASA Technical Reports Server (NTRS)

    Good, Brian S.

    2003-01-01

    We compare dilute-limit segregation energies for selected BCC transition metal binaries computed using ab initio and quantum approximate energy method. Ab initio calculations are carried out using the CASTEP plane-wave pseudopotential computer code, while quantum approximate results are computed using the Bozzolo-Ferrante-Smith (BFS) method with the most recent parameterization. Quantum approximate segregation energies are computed with and without atomistic relaxation. The ab initio calculations are performed without relaxation for the most part, but predicted relaxations from quantum approximate calculations are used in selected cases to compute approximate relaxed ab initio segregation energies. Results are discussed within the context of segregation models driven by strain and bond-breaking effects. We compare our results with other quantum approximate and ab initio theoretical work, and available experimental results.

  9. Polar pattern formation in driven filament systems requires non-binary particle collisions

    NASA Astrophysics Data System (ADS)

    Suzuki, Ryo; Weber, Christoph A.; Frey, Erwin; Bausch, Andreas R.

    2015-10-01

    From the self-organization of the cytoskeleton to the synchronous motion of bird flocks, living matter has the extraordinary ability to behave in a concerted manner. The Boltzmann equation for self-propelled particles is frequently used in silico to link a system’s meso- or macroscopic behaviour to the microscopic dynamics of its constituents. But so far such studies have relied on an assumption of simplified binary collisions owing to a lack of experimental data suggesting otherwise. We report here experimentally determined binary-collision statistics by studying a recently introduced molecular system, the high-density actomyosin motility assay. We demonstrate that the alignment induced by binary collisions is too weak to account for the observed ordering transition. The transition density for polar pattern formation decreases quadratically with filament length, indicating that multi-filament collisions drive the observed ordering phenomenon and that a gas-like picture cannot explain the transition of the system to polar order. Our findings demonstrate that the unique properties of biological active-matter systems require a description that goes well beyond that developed in the framework of kinetic theories.

  10. Lorentz invariant relative velocity and relativistic binary collisions

    NASA Astrophysics Data System (ADS)

    Cannoni, Mirco

    2017-01-01

    This paper reviews the concept of Lorentz invariant relative velocity that is often misunderstood or unknown in high energy physics literature. The properties of the relative velocity allow to formulate the invariant flux and cross-section without recurring to nonphysical velocities or any assumption about the reference frame. Applications such as the luminosity of a collider, the use as kinematic variable, and the statistical theory of collisions in a relativistic classical gas are reviewed. It is emphasized how the hyperbolic properties of the velocity space explain the peculiarities of relativistic scattering.

  11. Explosions triggered by violent binary-star collisions: application to Eta Carinae and other eruptive transients

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2011-08-01

    This paper discusses a scenario where a violent periastron collision of stars in an eccentric binary system induces an eruption or explosion seen as a brief transient source, attributed to luminous blue variables (LBVs), supernova (SN) impostors or other transients. The key ingredient is that an evolved primary increases its photospheric radius on relatively short (year to decade) time-scales, to a point where the radius is comparable to or larger than the periastron separation in an eccentric binary. In such a configuration, a violent and sudden collision would ensue, possibly leading to substantial mass ejection instead of a merger. Sudden energy deposition during the encounter could drive expansion of the optically thick envelope, causing a luminous transient source. Repeated periastral grazings in an eccentric system could quickly escalate to a catastrophic encounter. Outbursts triggered by tidal disturbances or powered by secondary accretion of the primary star's wind have been suggested previously. Instead, this paper proposes a much more violent encounter where the companion star plunges deep inside the photosphere of a bloated primary during periastron, as a result of the primary star increasing its own radius. This is motivated by the case of Eta Carinae, where such a collision must have occurred if conventional estimates of the present-day orbit are correct and where peaks in the light curve coincide with times of periastron. Stellar collisions may explain brief recurring LBV outbursts, such as SN 2000ch and SN 2009ip, and perhaps outbursts from intermediate-mass progenitor stars (i.e. collisions are not necessarily the exclusive domain of very luminous stars), but they cannot explain all non-SN transients. Finally, mass ejections induced repeatedly at periastron cause orbital evolution; this may explain the origin of eccentric Wolf-Rayet binaries such as WR 140.

  12. A local collision probability approximation for predicting momentum transfer cross sections.

    PubMed

    Bleiholder, Christian

    2015-10-21

    The local collision probability approximation (LCPA) method is introduced to compute molecular momentum transfer cross sections for comparison to ion mobility experiments. The LCPA replaces the (non-local) scattering trajectory used in the trajectory method to describe the collision process by a (local) collision probability function. This momentum transfer probability is computed using the exact same analyte-buffer interaction potential as used in the trajectory method. Subsequently, the momentum transfer cross section ΩLCPA(T) is calculated in a projection-type manner (corrected for shape effects through a shape factor). Benchmark calculations on a set of 208 carbon clusters with a range of molecular size and degree of concavity demonstrate that LCPA and trajectory calculations agree closely with one another. The results discussed here indicate that the LCPA is suitable to efficiently calculate momentum transfer cross sections for use in ion mobility spectrometry in conjunction with different buffer gases.

  13. Hierarchical approximate policy iteration with binary-tree state space decomposition.

    PubMed

    Xu, Xin; Liu, Chunming; Yang, Simon X; Hu, Dewen

    2011-12-01

    In recent years, approximate policy iteration (API) has attracted increasing attention in reinforcement learning (RL), e.g., least-squares policy iteration (LSPI) and its kernelized version, the kernel-based LSPI algorithm. However, it remains difficult for API algorithms to obtain near-optimal policies for Markov decision processes (MDPs) with large or continuous state spaces. To address this problem, this paper presents a hierarchical API (HAPI) method with binary-tree state space decomposition for RL in a class of absorbing MDPs, which can be formulated as time-optimal learning control tasks. In the proposed method, after collecting samples adaptively in the state space of the original MDP, a learning-based decomposition strategy of sample sets was designed to implement the binary-tree state space decomposition process. Then, API algorithms were used on the sample subsets to approximate local optimal policies of sub-MDPs. The original MDP was decomposed into a binary-tree structure of absorbing sub-MDPs, constructed during the learning process, thus, local near-optimal policies were approximated by API algorithms with reduced complexity and higher precision. Furthermore, because of the improved quality of local policies, the combined global policy performed better than the near-optimal policy obtained by a single API algorithm in the original MDP. Three learning control problems, including path-tracking control of a real mobile robot, were studied to evaluate the performance of the HAPI method. With the same setting for basis function selection and sample collection, the proposed HAPI obtained better near-optimal policies than previous API methods such as LSPI and KLSPI.

  14. On the Validity of the Adiabatic Approximation in Compact Binary Inspirals

    NASA Astrophysics Data System (ADS)

    Maselli, Andrea; Gualtieri, Leonardo; Ferrari, Valeria; Pannarale, Francesco

    2015-01-01

    We use the post-Newtonian-Affine model to assess the validity of the adiabatic approximation in modeling tidal effects in the phase evolution of compact binary systems. We compute the dynamical evolution of the tidal tensor, which we estimate at the 2PN order, and of the quadrupole tensor, finding that their ratio, i.e. the tidal deformability, increases in the last phases of the inspiral. We derive the gravitational wave phase corrections due to this phenomenon and quantify how they affect gravitational wave detectability.

  15. Grazing Collision of Binary Black Holes II: From Merger Towards Ringdown

    NASA Astrophysics Data System (ADS)

    Shoemaker, Deirdre

    2000-04-01

    One of the great challenges in gravitational physics is to simulate the collision of two black holes in order to study the resulting gravitational radiation. The Agave collaboration has successfully collided two spinning black holes in a grazing merger. The eventual goal of this work is to simulate the orbit, merger and ringdown stages of an astrophysical binary black hole system. The success of the grazing collision has proven to be strongly dependent on predicting the dynamics of the apparent horizons during the evolution. This is due to the fact that the region inside the apparent horizon containing the singularity is removed from the computational domain. Once the black holes have merged, one is left with a single black hole horizon. The spacetime is of a highly distorted black hole. We present results from simulations of the merged to ringdown stage in the life of a binary black hole collision. We show not only how crucial a role the dynamics of the apparent horizon plays in extending the lifetime of the simulation towards ringdown, but also the vital role the appropriate prescription of gauge conditions plays.

  16. On the quantum mechanical theory of collisional recombination rates, II. Beyond the strong collision approximation

    SciTech Connect

    Miller, W.H.

    1995-07-01

    A quantum mechanical theory of collisional recombination (within the Lindemann mechanism, A + B {leftrightarrow} AB*, AB* + M {yields} AB + M) is presented which provides a proper quantum description of the A + B collision dynamics and treats the M + AB* inelastic scattering within the impact approximation (the quantum analog of a classical master equation treatment). The most rigorous version of the theory is similar in structure to the impact theory of spectral line broadening and involves generalized (4-index) rate constants for describing M + AB* collisions. A simplified version is also presented which involves only the normal (2-index) inelastic rate constants for M + AB* scattering but which also retains a proper quantum description of the A + B dynamics.

  17. An angular momentum approximation for molecular collisions in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    Devries, P. L.; George, T. F.

    1979-01-01

    An approximation to a previously presented rigorous description of molecular (atom-atom) collisions occurring in the presence of intense radiation is investigated. This rigorous description explicitly considers the angular momentum transferred between the molecule and the radiation field in the absorption or emission of a photon, but involves a complicated system of close-coupled equations which must be solved independently for each projection M of the initial, total molecular angular momentum. (This is a direct consequence of the lack of rotational invariance in the molecule-field problem). These equations are solved for a model system which mimics the collision of a halogen with a rare gas atom. Empirical observations made in the course of performing these calculations lead to the development of an approximation which avoids the repeated calculations for each initial M. This orientational average approximation greatly reduces the effort required to describe the system, and for the model calculation, yields accurate results for field intensities as high as 10 GW/sq cm.

  18. On the validity of the adiabatic approximation in compact binary inspirals

    NASA Astrophysics Data System (ADS)

    Maselli, Andrea; Gualtieri, Leonardo; Pannarale, Francesco; Ferrari, Valeria

    2012-08-01

    Using a semianalytical approach recently developed to model the tidal deformations of neutron stars in inspiralling compact binaries, we study the dynamical evolution of the tidal tensor, which we explicitly derive at second post-Newtonian order, and of the quadrupole tensor. Since we do not assume a priori that the quadrupole tensor is proportional to the tidal tensor, i.e., the so-called “adiabatic approximation,” our approach enables us to establish to which extent such approximation is reliable. We find that the ratio between the quadrupole and tidal tensors (i.e., the Love number) increases as the inspiral progresses, but this phenomenon only marginally affects the emitted gravitational waveform. We estimate the frequency range in which the tidal component of the gravitational signal is well described using the Stationary phase approximation at next-to-leading post-Newtonian order, comparing different contributions to the tidal phase. We also derive a semianalytical expression for the Love number, which reproduces within a few percentage points the results obtained so far by numerical integrations of the relativistic equations of stellar perturbations.

  19. SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

    SciTech Connect

    Prodan, Snezana; Antonini, Fabio; Perets, Hagai B. E-mail: antonini@cita.utoronto.ca

    2015-02-01

    Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change their orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center.

  20. Coulomb explosion and binary encounter processes in collisions between slow ions and small molecules of biological interest

    SciTech Connect

    Juhasz, Z.; Sulik, B.

    2008-12-08

    In this work we study the ion impact induced fragmentation of small molecules, which are relevant for radiation damage studies in biological tissues. We present double differential ion emission yields for collisions of N{sup 6+} ions with water and methane molecules at 15 and 30 keV impact energies. The angular distribution of the fragment ions shows post-collision and nucleus-nucleus binary collision effects. In the multiple capture energy range, a strong interplay is indicated between the Coulomb explosion and the binary collision mechanisms. In the energy region, where triple capture is dominant, an unexpected angular distribution was found for water fragments, which may be attributed to orientation sensitivity of some of the capture channels. Such processes are relevant for astrophysics and radiation therapy.

  1. Computational test of the infinite order sudden approximation for excitation of linear rigid rotors by collisions with atoms

    NASA Technical Reports Server (NTRS)

    Green, S.

    1978-01-01

    The infinite order sudden approximation for excitation of linear rigid rotors by collisions with atom is tested by comparing integral state-to-state cross sections with accurate close coupling and coupled states results. The systems studied are HCl-Ar, HCl-He, CO-He, HCN-He, CS-H2 and OCS-H2. With the exception of diatomic hydrides (e.g., HCl) which have atypically large rotational constants the method is found to be very accurate to remarkably low collision energies. This approximation should generally be extremely useful for thermal energy collisions.

  2. Macroscopic Model for Head-On Binary Droplet Collisions in a Gaseous Medium

    NASA Astrophysics Data System (ADS)

    Li, Jie

    2016-11-01

    In this Letter, coalescence-bouncing transitions of head-on binary droplet collisions are predicted by a novel macroscopic model based entirely on fundamental laws of physics. By making use of the lubrication theory of Zhang and Law [Phys. Fluids 23, 042102 (2011)], we have modified the Navier-Stokes equations to accurately account for the rarefied nature of the interdroplet gas film. Through the disjoint pressure model, we have incorporated the intermolecular van der Waals forces. Our model does not use any adjustable (empirical) parameters. It therefore encompasses an extreme range of length scales (more than 5 orders of magnitude): from those of the external flow in excess of the droplet size (a few hundred μ m ) to the effective range of the van der Waals force around 10 nm. A state of the art moving adaptive mesh method, capable of resolving all the relevant length scales, has been employed. Our numerical simulations are able to capture the coalescence-bouncing and bouncing-coalescence transitions that are observed as the collision intensity increases. The predicted transition Weber numbers for tetradecane and water droplet collisions at different pressures show good agreement with published experimental values. Our study also sheds new light on the roles of gas density, droplet size, and mean free path in the rupture of the gas film.

  3. Binary-State Dynamics on Complex Networks: Pair Approximation and Beyond

    NASA Astrophysics Data System (ADS)

    Gleeson, James P.

    2013-04-01

    A wide class of binary-state dynamics on networks—including, for example, the voter model, the Bass diffusion model, and threshold models—can be described in terms of transition rates (spin-flip probabilities) that depend on the number of nearest neighbors in each of the two possible states. High-accuracy approximations for the emergent dynamics of such models on uncorrelated, infinite networks are given by recently developed compartmental models or approximate master equations (AMEs). Pair approximations (PAs) and mean-field theories can be systematically derived from the AME. We show that PA and AME solutions can coincide under certain circumstances, and numerical simulations confirm that PA is highly accurate in these cases. For monotone dynamics (where transitions out of one nodal state are impossible, e.g., susceptible-infected disease spread or Bass diffusion), PA and the AME give identical results for the fraction of nodes in the infected (active) state for all time, provided that the rate of infection depends linearly on the number of infected neighbors. In the more general nonmonotone case, we derive a condition—that proves to be equivalent to a detailed balance condition on the dynamics—for PA and AME solutions to coincide in the limit t→∞. This equivalence permits bifurcation analysis, yielding explicit expressions for the critical (ferromagnetic or paramagnetic transition) point of such dynamics, that is closely analogous to the critical temperature of the Ising spin model. Finally, the AME for threshold models of propagation is shown to reduce to just two differential equations and to give excellent agreement with numerical simulations. As part of this work, the Octave or Matlab code for implementing and solving the differential-equation systems is made available for download.

  4. Binary collision theory for thermal and nonisothermal relaxation and reaction of polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Talkner, Peter; Pollak, Eli; Berezhkovskii, Alexander M.

    1998-09-01

    Many unimolecular reactions are initiated by photoexcitation of a polyatomic molecule at room temperature from its S 0 ground state to an electronically excited S 1 state. This excitation will generally lead to a nonisothermal initial distribution of energy in the excited state. Collisions with a buffer gas at room temperature tend to reequilibrate the reacting molecule. The ensuing radiative and nonradiative decay will depend on the competition between the energy dependent unimolecular decay rate and the energy relaxation. In this paper we describe a Gaussian binary collision theory which includes all three aspects - radiative decay, nonradiative decay and relaxation. The Gaussian property is justified when the reacting species is large enough, i.e. it has a large enough number of degrees of freedom such that the equilibrium distribution of the molecule can be described by a Gaussian. Guided by experimental observation, we adapt a Gaussian transition probability, which is similar to Mel'nikov's, to describe the relaxation dynamics. An analytic solution for the Gaussian master equation is presented. We find that pressure induced decay which is faster than the initial decay rate is an experimental signature of an initial cold distribution of reactants. This signature was observed experimentally in the isomerization of trans-stilbene. Application to the decay dynamics of the trans-stilbene molecule shows that an initial temperature of 230 K for trans-stilbene in the excited S 1 state suffices for good agreement between the theoretical and experimental survival probability measured at a gas temperature of 300 K.

  5. Comparison of the binary logistic and skewed logistic (Scobit) models of injury severity in motor vehicle collisions.

    PubMed

    Tay, Richard

    2016-03-01

    The binary logistic model has been extensively used to analyze traffic collision and injury data where the outcome of interest has two categories. However, the assumption of a symmetric distribution may not be a desirable property in some cases, especially when there is a significant imbalance in the two categories of outcome. This study compares the standard binary logistic model with the skewed logistic model in two cases in which the symmetry assumption is violated in one but not the other case. The differences in the estimates, and thus the marginal effects obtained, are significant when the assumption of symmetry is violated.

  6. The Binary Collision-Induced Second Overtone Band of Gaseous Hydrogen: Modelling and Laboratory Measurements

    NASA Technical Reports Server (NTRS)

    Brodbeck, C.; Bouanich, J.-P.; Nguyen, Van Thanh; Borysow, Aleksandra

    1999-01-01

    Collision-induced absorption (CIA) is the major source of the infrared opacity of dense planetary atmospheres which are composed of nonpolar molecules. Knowledge of CIA absorption spectra of H2-H2 pairs is important for modelling the atmospheres of planets and cold stars that are mainly composed of hydrogen. The spectra of hydrogen in the region of the second overtone at 0.8 microns have been recorded at temperatures of 298 and 77.5 K for gas densities ranging from 100 to 800 amagats. By extrapolation to zero density of the absorption coefficient measured every 10 cm(exp -1) in the spectral range from 11100 to 13800 cm(exp -1), we have determined the binary absorption coefficient. These extrapolated measurements are compared with calculations based on a model that was obtained by using simple computer codes and lineshape profiles. In view of the very weak absorption of the second overtone band, we find the agreement between results of the model and experiment to be reasonable.

  7. Energy loss of ions in a magnetized plasma: conformity between linear response and binary collision treatments.

    PubMed

    Nersisyan, H B; Zwicknagel, G; Toepffer, C

    2003-02-01

    The energy loss of a heavy ion moving in a magnetized electron plasma is considered within the linear response (LR) and binary collision (BC) treatments with the purpose to look for a connection between these two models. These two complementary approaches yield close results if no magnetic field is present, but there develop discrepancies with growing magnetic field at ion velocities that are lower than, or comparable with, the thermal velocity of the electrons. We show that this is a peculiarity of the Coulomb interaction which requires cutoff procedures to account for its singularity at the origin and its infinite range. The cutoff procedures in the LR and BC treatments are different as the order of integrations in velocity and in ordinary (Fourier) spaces is reversed in both treatments. While BC involves a velocity average of Coulomb logarithms, there appear in LR Coulomb logarithms of velocity averaged cutoffs. The discrepancies between LR and BC vanish, except for small contributions of collective modes, for smoothened potentials that require no cutoffs. This is shown explicitly with the help of an improved BC in which the velocity transfer is treated up to second order in the interaction in Fourier space.

  8. Laser-assisted binary rearrangement collision: e++H-->Ps+p

    NASA Astrophysics Data System (ADS)

    Shu-Min, Li; Zi-Fang, Zhou; Jian-Ge, Zhou; Yao-Yang, Liu

    1993-06-01

    In the first Born approximation, the laser-assisted rearrangement collision between a positron and a hydrogen atom is systematically studied. In solving the dressed wave functions, the A.p gauge is adopted. To overcome the difficulty in the reduction of the S matrix, we have developed the Feynman integration technique. The scattering amplitude is reduced to one-dimensional integrals and analytical expressions. The numerical calculation is greatly simplified, which makes it possible to compute the integral cross sections for Ps formation including multiphoton processes. Our results indicate that when the laser field is presented, the cross sections for Ps formation are remarkably enhanced. This is of great importance in improving this kind of reaction.

  9. The effect of rheological approximations on the dynamics and topography in 3D subduction-collision models

    NASA Astrophysics Data System (ADS)

    Pusok, Adina E.; Kaus, Boris J. P.; Popov, Anton A.

    2016-04-01

    Most of the major mountain belts and orogenic plateaus are found within the overlying plate of active or fossil subduction and/or collision zones. Moreover, they evolve differently from one another as the result of specific combinations of surface and mantle processes. These differences arise for several reasons, such as different rheological properties, different amounts of regional isostatic compensation, and different mechanisms by which forces are applied to the convergent plates. Previous 3D geodynamic models of subduction/collision processes have used various rheological approximations, making numerical results difficult to compare, since there is no clear image on the extent of these approximations on the dynamics. Here, we employ the code LaMEM to perform high-resolution long-term 3D simulations of subduction/continental collision in an integrated lithospheric and upper-mantle scale model. We test the effect of rheological approximations on mantle and lithosphere dynamics in a geometrically simplified model setup that resembles a tectonic map of the India-Asia collision zone. We use the "sticky-air" approach to allow for the development of topography and the dynamics of subduction and collision is entirely driven by slab-pull (i.e. "free subduction"). The models exhibit a wide range of behaviours depending on the rheological law employed: from linear to temperature-dependent visco-elasto-plastic rheology that takes into account both diffusion and dislocation creep. For example, we find that slab dynamics varies drastically between end member models: in viscous approximations, slab detachment is slow following a viscous thinning, while for a non-linear visco-elasto-plastic rheology, slab detachment is relatively fast, inducing strong mantle flow in the slab window. We also examine the stress states in the subducting and overriding plates and topography evolution in the upper plate, and we discuss the implications on lithosphere dynamics at convergent margins

  10. Film model approximation for particle-diffusion-controlled binary ion exchange

    SciTech Connect

    Carta, G.; Cincotti, A.; Cao, G.

    1999-01-01

    A new rate expression for particle-diffusion-controlled ion exchange, based on an equivalent pseudosteady-state film resistance model, is developed. The rate expression approximates the electric field effects on intraparticle diffusion in spherical ion-exchangers. With regard to the prediction of batch exchange and column breakthrough curves for both irreversible and reversible processes, the model captures the essential traits of the coupled diffusion phenomenon described by the Nernst-Planck equation with results of accuracy comparable to that obtained when using the linear driving force approximation for systems with constant diffusivity. Numerical results for the exchange of two counterions of equal valence are presented as application examples for different mobility ratios and selectivity coefficients.

  11. Gravitational self-force meets the post-Newtonian approximation in extreme-mass ratio inspiral of binary black holes

    NASA Astrophysics Data System (ADS)

    Detweiler, Steven

    2010-02-01

    Post-Newtonian analysis, numerical relativity and, now, perturbation-based gravitational self-force analysis are all being used to describe various aspects of black hole binary systems. Recent comparisons between self-force analysis, with m1m2, and post-Newtonian analysis, with v/c 1 show excellent agreement in their common domain of validity. This lends credence to the two very different regularization procedures which are invoked in these approximations. When self-force analysis is able to create gravitational waveforms from extreme mass-ratio inspiral, then unprecedented cross cultural comparisons of these three distinct approaches to understanding gravitational waves will reveal the strengths and weaknesses of each. )

  12. Simulation of binary droplet collisions with the entropic lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Mazloomi Moqaddam, Ali; Chikatamarla, Shyam S.; Karlin, Ilya V.

    2016-02-01

    The recently introduced entropic lattice Boltzmann method (ELBM) for multiphase flows is extended here to simulation of droplet collisions. Thermodynamically consistent, non-linearly stable ELBM together with a novel polynomial equation of state is proposed for simulation large Weber and Reynolds number collisions of two droplets. Extensive numerical investigations show that ELBM is capable of accurately capturing the dynamics and complexity of droplet collision. Different types of the collision outcomes such as coalescence, reflexive separation, and stretching separation are identified. Partition of the parameter plane is compared to the experiments and excellent agreement is observed. Moreover, the evolution of the shape of a stable lamella film is quantitatively compared with experimental results. The end pinching and the capillary-wave instability are shown to be the main mechanisms behind formation of satellite droplets for near head-on and off-center collisions with high impact parameter, respectively. It is shown that the number of satellite drops increases with increasing Weber number, as predicted by experiments. Also, it is demonstrated that the rotational motion due to angular momentum and elongation of the merged droplet play essential roles in formation of satellite droplets in off-center collisions with an intermediate impact parameter.

  13. Charge exchange transition probability for collisions between unlike ions and atoms within the adiabatic approximation

    NASA Technical Reports Server (NTRS)

    Xu, Y. J.; Khandelwal, G. S.; Wilson, John W.

    1989-01-01

    A simple formula for the transition probability for electron exchange between unlike ions and atoms is established within the adiabatic approximation by employing the Linear Combination of Atomic Orbitals (LCAO) method. The formula also involves an adiabatic parameter, introduced by Massey, and thus the difficulties arising from the internal energy defect and the adiabatic approximation are avoided. Specific reactions Li(+++) + H to Li(++) + H(+) and Be(4+) + H to Be(3+) + H(+) are considered as examples. The calculated capture cross section results of the present work are compared with the experimental data and with the calculation of other authors over the velocity range of 10(7) cm/sec to 10(8) cm/sec.

  14. Molecular collisions. 11: Semiclassical approximation to atom-symmetric top rotational excitation

    NASA Technical Reports Server (NTRS)

    Russell, D.; Curtiss, C. F.

    1973-01-01

    In a paper of this series a distorted wave approximation to the T matrix for atom-symmetric top scattering was developed which is correct to first order in the part of the interaction potential responsible for transitions in the component of rotational angular momentum along the symmetry axis of the top. A semiclassical expression for this T matrix is derived by assuming large values of orbital and rotational angular momentum quantum numbers.

  15. Ionization collisions between two excited atoms: Application of the Glauber amplitude in the framework of the impulse approximation

    SciTech Connect

    Shirai, T.; Nakai, Y.; Nakamura, H.

    1984-10-01

    The cross-section formula of Flannery (Phys. Rev. A 22, 2408 (1980)) in the semiquantal approximation for the processes referred to in the title is rewritten so as to make it more useful in practice. The formula is shown to be further simplified by taking an average over the azimuthal quantum number of a highly excited hydrogenic atom to be ionized. Numerical applications with use of the Glauber amplitude for the electron-atom inelastic scattering are made to the ionization collisions between two excited hydrogen atoms with simultaneous excitation and deexcitation of one of the atoms. The results are compared with those obtained by using the Born amplitude, and are analyzed in terms of the Glauber generalized oscillator strengths.

  16. Hans A. Bethe Prize: Cosmic Collisions Online - Compact Binary Mergers, Gravitational Waves and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Shapiro, Stuart

    2017-01-01

    Hans A. Bethe elucidated our understanding of the fundamental forces of Nature by exploring and explaining countless phenomena occurring in nuclear laboratories and in stars. With the dawn of gravitational wave astronomy we now can probe compact binary mergers - Nature's cosmic collision experiments - to deepen our understanding, especially where strong-field gravitation is involved. In addition to gravitational waves, some mergers are likely to generate observable electromagnetic and/or neutrino radiation, heralding a new era of multimessenger astronomy. Robust numerical algorithms now allow us to simulate these events in full general relativity on supercomputers. We will describe some recent magnetohydrodynamic simulations that show how binary black hole-neutron star and neutron star-neutron star mergers can launch jets, lending support to the idea that such mergers could be the engines that power short gamma-ray bursts. We will also show how the magnetorotational collapse of very massive stars to spinning black holes immersed in magnetized accretion disks can launch jets as well, reinforcing the belief that such ``collapsars'' are the progenitors of long gamma-ray bursts. Computer-generated movies highlighting some of these simulations will be shown. We gratefully acknowledge support from NSF Grants 1300903 and 1602536 and NASA Grant NNX13AH44G.

  17. Validity of the thin viscous sheet approximation in models of continental collision

    NASA Astrophysics Data System (ADS)

    Garthwaite, Matthew C.; Houseman, Gregory A.

    2011-02-01

    The two-dimensional thin viscous sheet approximation is widely used to describe large-scale continental deformation. It treats the lithosphere as a fluid layer in which deformation results from a balance between buoyancy forces and tectonic boundary conditions. Comparisons between two-dimensional thin sheet and full three-dimensional solutions of a simple indenter model show that appreciable differences exist, especially when the indenter half width, D, is of the same order as the thickness of the deforming layer, L (i.e., D/L ≈ 1). These differences are amplified by increasing the power law exponent of the viscous constitutive law (n) but decrease as the Argand number (Ar) is increased. The greatest differences between two-dimensional and three-dimensional solutions are found at the indenter corner, where the thin sheet consistently overestimates vertical strain rates. Differences between strain rates at the corner may be 50% or greater for small Argand numbers. Other differences arise because a lithospheric root zone is formed in the three-dimensional solutions and vertically averaged strain rate is decreased in regions close to the indenter. This effect is absent from thin sheet calculations since the thickness of the load-bearing layer is assumed constant. In general, the thin viscous sheet approximation provides a reasonably accurate estimate of long wavelength deformation for D/L as low as 1 if n is less than ˜3. However, even at large D/L the solutions may be inaccurate close to strain rate concentrations at the indenter corners where horizontal gradients of deformation are large.

  18. Relativistic Brownian motion: from a microscopic binary collision model to the Langevin equation.

    PubMed

    Dunkel, Jörn; Hänggi, Peter

    2006-11-01

    The Langevin equation (LE) for the one-dimensional relativistic Brownian motion is derived from a microscopic collision model. The model assumes that a heavy pointlike Brownian particle interacts with the lighter heat bath particles via elastic hard-core collisions. First, the commonly known, nonrelativistic LE is deduced from this model, by taking into account the nonrelativistic conservation laws for momentum and kinetic energy. Subsequently, this procedure is generalized to the relativistic case. There, it is found that the relativistic stochastic force is still delta correlated (white noise) but no longer corresponds to a Gaussian white noise process. Explicit results for the friction and momentum-space diffusion coefficients are presented and discussed.

  19. Non-Hertzian behavior in binary collisions of plastic balls derived from impact acoustics.

    PubMed

    Riner, Joshua; Petculescu, Andi

    2010-07-01

    This paper presents slight deviations from Hertz's impact law, inferred from acoustic signatures of polypropylene ball collisions. An impact acoustics model is used to fit the acoustic data. The model is built upon a generalized relationship between impact force (F) and deformation (xi) of the form F=kappaxi(alpha). Agreement with experiment is reached when alpha and kappa differ from Hertz's values by -6.25% and +1%, respectively. The difference is ascribable to non-idealities such as slight material inhomogeneities, impact-point asymmetry, plasticity etc. Also, the collision energy released as sound, which is usually dismissed as negligible, is derived from data fitting. The acoustic-to-incident energy ratio, dependent on impact duration, is constrained to be on the order of 100 ppm.

  20. Hydrodynamics of passing-over motion during binary droplet collision in shear flow

    NASA Astrophysics Data System (ADS)

    Wang, Cheng-Yao; Zhang, Cheng-Bin; Huang, Xiang-Yong; Liu, Xiang-Dong; Chen, Yong-Ping

    2016-10-01

    A combined experimental and numerical study is undertaken to investigate the hydrodynamic characteristics of single-phase droplet collision in a shear flow. The passing-over motion of interactive droplets is observed, and the underlying hydrodynamic mechanisms are elucidated by the analysis of the motion trajectory, transient droplet deformation and detailed hydrodynamic information (e.g., pressure and flow fields). The results indicate that the hydrodynamic interaction process under shear could be divided into three stages: approaching, colliding, and separating. With the increasing confinement, the interaction time for the passing-over process is shorter and the droplet processes one higher curvature tip and more stretched profile. Furthermore, the lateral separation Δy/R 1 exhibits larger decrease in the approaching stage and the thickness of the lubrication film is decreased during the interaction. As the initial lateral separation increases, the maximum trajectory shift by the collision interaction is getting smaller. During the collision between two droplets with different sizes, the amplitude of the deformation oscillation of the larger droplet is decreased by reducing the size ratio of the smaller droplet to the bigger one. Project supported by the NSAF (Grants No. U1530260), the National Natural Science Foundation of China (Grant No. 51306158), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20130621), and the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase).

  1. Analyzing the delta Sco Binary in Anticipation of a Disk-Star Collision

    DTIC Science & Technology

    2011-01-01

    Tango et al. 2009). The goal for this project is to refine the orbit of the secondary with respect to the primary and test for the possibility of a...to the primary. The NPOI observations were compared to orbits based on parameters from Mason et al. (2009), Tango et al. (2009), and Miroshnichenko et...date has been 278 δ Sco binary 279 Table 1. The orbital elements for δ Sco. Element Mason et al. Miroshnichenko Tango et al. This Work (2009) et al

  2. Uranyl(VI) nitrate salts: modeling thermodynamic properties using the binding mean spherical approximation theory and determination of "fictive" binary data.

    PubMed

    Ruas, Alexandre; Bernard, Olivier; Caniffi, Barbara; Simonin, Jean-Pierre; Turq, Pierre; Blum, Lesser; Moisy, Philippe

    2006-02-23

    This work is aimed at a description of the thermodynamic properties of highly concentrated aqueous solutions of uranyl nitrate at 25 degrees C. A new resolution of the binding mean spherical approximation (BIMSA) theory, taking into account 1-1 and also 1-2 complex formation, is developed and used to reproduce, from a simple procedure, experimental uranyl nitrate osmotic coefficient variation with concentration. For better consistency of the theory, binary uranyl perchlorate and chloride osmotic coefficients are also calculated. Comparison of calculated and experimental values is made. The possibility of regarding the ternary system UO(2)(NO(3))(2)/HNO(3)/H(2)O as a "simple" solution (in the sense of Zdanovskii, Stokes, and Robinson) is examined from water activity and density measurements. Also, an analysis of existing uranyl nitrate binary data is proposed and compared with our obtained data. On the basis of the concept of "simple" solution, values for density and water activity for the binary system UO(2)(NO(3))(2)/H(2)O are proposed in a concentration range on which uranyl nitrate precipitates from measurements on concentrated solutions of the ternary system UO(2)(NO(3))(2)/HNO(3)/H(2)O. This new set of binary data is "fictive" in the sense that the real binary system is not stable chemically. Finally, a new, interesting predictive capability of the BIMSA theory is shown.

  3. Single differential electron impact ionization cross sections in the binary-encounter-Bethe approximation for the low binding energy regime

    NASA Astrophysics Data System (ADS)

    Guerra, M.; Amaro, P.; Machado, J.; Santos, J. P.

    2015-09-01

    An analytical expression based on the binary-encounter-Bethe model for energy differential cross sections in the low binding energy regime is presented. Both the binary-encounter-Bethe model and its modified counterpart are extended to shells with very low binding energy by removing the constraints in the interference term of the Mott cross section, originally introduced by Kim et al. The influence of the ionic factor is also studied for such targets. All the binary-encounter-Bethe based models presented here are checked against experimental results of low binding energy targets, such as the total ionization cross sections of alkali metals. The energy differential cross sections for H and He, at several incident energies, are also compared to available experimental and theoretical values.

  4. Simulating the ballistic effects of ion irradiation in the binary collision approximation: A first step toward the ion mixing framework

    NASA Astrophysics Data System (ADS)

    Demange, G.; Antoshchenkova, E.; Hayoun, M.; Lunéville, L.; Simeone, D.

    2017-04-01

    Understanding ballistic effects induced by ion beam irradiation can be a key point for controlling and predicting the microstructure of irradiated materials. Meanwhile, the ion mixing framework suggests an average description of displacement cascades may be sufficient to estimate the influence of ballistic relocations on the microstructure. In this work, the BCA code MARLOWE was chosen for its ability to account for the crystal structure of irradiated materials. A first set of simulations was performed on pure copper for energies ranging from 0.5 keV to 20 keV. These simulations were validated using molecular dynamics (MD). A second set of simulations on AgCu irradiated by 1 MeV krypton ions was then carried out using MARLOWE only, as such energy is beyond reach for molecular dynamics. MARLOWE simulations are found to be in good agreement with experimental results, which suggests the predictive potential of the method.

  5. Non-equilibrium of charged particles in swarms and plasmas—from binary collisions to plasma effects

    NASA Astrophysics Data System (ADS)

    Petrović, Z. Lj; Simonović, I.; Marjanović, S.; Bošnjaković, D.; Marić, D.; Malović, G.; Dujko, S.

    2017-01-01

    In this article we show three quite different examples of low-temperature plasmas, where one can follow the connection of the elementary binary processes (occurring at the nanoscopic scale) to the macroscopic discharge behavior and to its application. The first example is on the nature of the higher-order transport coefficient (second-order diffusion or skewness); how it may be used to improve the modelling of plasmas and also on how it may be used to discern details of the relevant cross sections. A prerequisite for such modeling and use of transport data is that the hydrodynamic approximation is applicable. In the second example, we show the actual development of avalanches in a resistive plate chamber particle detector by conducting kinetic modelling (although it may also be achieved by using swarm data). The current and deposited charge waveforms may be predicted accurately showing temporal resolution, which allows us to optimize detectors by adjusting the gas mixture composition and external fields. Here kinetic modeling is necessary to establish high accuracy and the details of the physics that supports fluid models that allows us to follow the transition to streamers. Finally, we show an example of positron traps filled with gas that, for all practical purposes, are a weakly ionized gas akin to swarms, and may be modelled in that fashion. However, low pressures dictate the need to apply full kinetic modelling and use the energy distribution function to explain the kinetics of the system. In this way, it is possible to confirm a well established phenomenology, but in a manner that allows precise quantitative comparisons and description, and thus open doors to a possible optimization.

  6. Experimental determination of water activity for binary aqueous cerium(III) ionic solutions: application to an assessment of the predictive capability of the binding mean spherical approximation model.

    PubMed

    Ruas, Alexandre; Simonin, Jean-Pierre; Turq, Pierre; Moisy, Philippe

    2005-12-08

    This work is aimed at a description of the thermodynamic properties of actinide salt solutions at high concentration. The predictive capability of the binding mean spherical approximation (BIMSA) theory to describe the thermodynamic properties of electrolytes is assessed in the case of aqueous solutions of lanthanide(III) nitrate and chloride salts. Osmotic coefficients of cerium(III) nitrate and chloride were calculated from other lanthanide(III) salts properties. In parallel, concentrated binary solutions of cerium nitrate were prepared in order to measure experimentally its water activity and density as a function of concentration, at 25 degrees C. Water activities of several binary solutions of cerium chloride were also measured to check existing data on this salt. Then, the properties of cerium chloride and cerium nitrate solutions were compared within the BIMSA model. Osmotic coefficient values for promethium nitrate and promethium chloride given by this theory are proposed. Finally, water activity measurements were made to examine the fact that the ternary system Ce(NO3)3/HNO3/H2O and the quaternary system Ce(NO3)3/HNO3/N2H5NO3/H2O may be regarded as "simple solutions" (in the sense of Zdanovskii and Mikulin).

  7. A 8.9-ENOB 2.5-εW 150-KS/s non-binary redundant successive approximation ADC in 0.18-microm CMOS for bio-implanted devices.

    PubMed

    Chan, Kok Lim; Lee, Andreas Astuti; Yuan, Xiaojun; Krishna, Kotlanka R; Je, Minkyu

    2010-01-01

    A successive approximation analog-to-digital converter (SAR ADC) with a split-capacitor switching scheme implementing the generalized non-binary redundant SAR algorithm and an energy efficient level shifter is proposed for bio-implanted applications. The generalized non-binary redundant SAR algorithm removes the radix constraint in conventional non-binary redundant SAR algorithm, and the energy efficient level shifter allows optimal power supplies to be chosen independently for the analog and digital blocks. A FOM of 34.7fJ/step has been achieved.

  8. The Wind-Wind Collision Region of the Wolf-Rayet Binary V444 Cygni: How Much Optical Line Emission Does It Produce?

    NASA Astrophysics Data System (ADS)

    Flores, Aaron; Auer, Lawrence H.; Koenigsberger, Gloria; Cardona, Octavio

    2001-12-01

    We model the emission-line profile variations that are expected to be produced by physical and wind eclipses in the Wolf-Rayet (W-R+O) binary system V444 Cyg. A comparison of the theoretical profiles with the He II 4686 Å line observed in V444 Cyg allows us to isolate the effects that are likely to be due to the wind-wind collision region in this particular line. We estimate that the wind-wind collision region contributes no more than ~12% of the equivalent width of the emission line, with smaller values during elongations, when part of the shock cone is being eclipsed by the O star. The upper limit implies a maximum contribution from the wind-wind collision region of ~1×1035 ergs s-1 to the total luminosity of He II 4686 Å line. Using the analytical solution of Cantó et al., we find that the bulk of this emission arises along the shock cone walls where the flow velocity is ~800 km s-1, at a distance of ~8 Rsolar from the O star's surface, and at θ=65°-75° from the line joining the centers of the two stars, with origin in the O star. The derived surface density of this region is σ=0.22 g cm-2, which, together with the He II 4686 Å luminosity, indicates that the thickness of the shock lies in the range 2-10×1010 cm and the total density is 1-6×1012 cm-3.

  9. Constraining the minute amount of audible energy radiated from binary collisions of light plastic spheres in conditions of incomplete angular coverage of the measured pressure.

    PubMed

    Petculescu, Andi; Riner, Joshua

    2010-10-01

    Usually, the energy released as air-coupled sound following a collision is dismissed as negligible. The goal of this Letter is to quantify the value of this small but measurable quantity, since it can be useful to impact studies. Measurements of sound radiation from binary collisions of polypropylene balls were performed in order to constrain the fraction of incident energy radiated as sound in air. In the experiments, one ball is released from rest, directly above a stationary target ball. The transient acoustic waveforms are detected by a microphone rotated about the impact point at a radius of 10 cm. The sound pressure was measured as a function of the polar angle θ (the azimuthal symmetry of the problem was verified by rotating the microphone in the horizontal plane). The angular pattern has two main lobes that are asymmetric with respect to the impact plane. This asymmetry is ascribable to interference and/or scattering effects. Gaps in the acoustic measurements at the "poles" (i.e., around 0° and 180°) pose a challenge similar to that of extrapolating the cosmic microwave background in the galactic "cut." The data was continued in the gaps by polynomial interpolation rather than least-squares fitting, a choice dictated by the accuracy of the reconstructed pattern. The acoustic energy radiated during the impact, estimated by multiplying the collision time by the sound intensity integrated over a spherical surface centered at the impact point, is calculated as four orders of magnitude smaller than the incident energy (0.23 μJ versus 1.6 mJ).

  10. The Wind-Wind Collision Region of the Wolf-Rayet Binary V444 Cyg: How much optical line emission does it produce ?

    NASA Astrophysics Data System (ADS)

    Flores, A.; Auer, L. H.; Koenigsberger, G.; Cardona, O.

    2001-12-01

    We model the emission line profile variations that are expected to be produced by physical and wind eclipses in the Wolf-Rayet (WR+O) binary system V444 Cyg. A comparison of the theoretical profiles with the He II 4686 Å line observed in V444 Cyg allows us to isolate the effects that are likely to be due to the wind-wind collision region, in this particular line. We estimate that the WWC region contributes no more than ~ 12% of the equivalent width of the emission line, with smaller values during elongations, when part of the shock cone is being eclipsed by the O-star. The upper limit implies a maximum contribution from the wind-wind collision region of ~ 1.*E35 ergs s-1 to the total luminosity of He II 4686 Å line. Using the analytical solution of Cantó et al. (1996), we find that the bulk of this emission seems to be arising along the shock cone walls where the flow velocity is ~ 800 km s-1, at a distance of ~ 8 {Rsun }\\> from the O-star's surface, and at Θ =60-70o from the line joining the centers of the two stars, with origin in the O-star. The derived surface density of this region is σ =0.22 gr cm-2, which together with the He II 4686 Å luminosity, indicates that the thickness of the shock lies in the range 2-10 x 1010 cm and the total density is 1-6 x 1012 cm-3.

  11. Heavy ion collisions with A = 10/sup 57/: Aspects of nuclear stability and the nuclear equation of state in coalescing neutron-star binary systems

    SciTech Connect

    Mathews, G.J.; Wilson, J.R.; Evans, C.R.; Detweiler, S.L.

    1987-12-01

    The dynamics of the final stages of the coalescence of two neturon stars (such as the binary pulsar PSR 1913+16) is an unsolved problem in astrophysics. Such systems are probably efficient generators of gravitational radiation, and may be significant contributors to heavy-element nucleosynthesis. The input physics for the study of such systems is similar to that required for the strudy of heavy-ion collision hydrodynamics; e.g., a finite temperature nuclear equation of state, properties of nuclei away from stability, etc. We discuss the development of a relativistic hydrodynamics code in three spatial dimensions for the purpose of studying such neutron-star systems. The properties of the mass-radius relation (determined by the nuclear equation of state) may lead to a proposed mechanism by which hot, highly neutronized matter is ejected from the coalescing stars. This material is photodisintegrated into a free (mostly) neutron gas which may subsequently experience rapid-neutron capture (r-process) nucleosynthesis. 15 refs., 4 figs.

  12. Systematic approach for simultaneously correcting the band-gap andp-dseparation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

    DOE PAGES

    Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

    2015-07-31

    We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X = N,P,As,Sb, and II-VI compounds, (Zn or Cd)X, with X = O,S,Se,Te. By correcting (1) the binary band gaps at high-symmetry points , L, X, (2) the separation of p-and d-orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles methodmore » can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.« less

  13. Kuang's Semi-Classical Formalism for Electron Capture Cross-Sections in Ion-Ion Collisions at Approximately to MeV/amu: Application to ENA Modeling

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2012-01-01

    Recent discovery by STEREO A/B of energetic neutral hydrogen is spurring an interest and need for reliable estimates of electron capture cross sections at few MeVs per nucleon as well as for multi-electron ions. Required accuracy in such estimates necessitates detailed and involved quantum-mechanical calculations or expensive numerical simulations. For ENA modeling and similar purposes, a semi-classical approach offers a middle-ground approach. Kuang's semiclassical formalism to calculate electron-capture cross sections for single and multi-electron ions is an elegant and efficient method, but has so far been applied to limited and specific laboratory measurements and at somewhat lower energies. Our goals are to test and extend Kuang s method to all ion-atom and ion-ion collisions relevant to ENA modeling, including multi-electron ions and for K-shell to K-shell transitions.

  14. Discovery of Nearly Coherent Oscillations with a Frequency of approximately 567 Hz During Type I X-ray Bursts of the X-ray Transient and Eclipsing Binary X1658-298

    NASA Technical Reports Server (NTRS)

    Wijnands, Rudy; Strohmayer, Tod; Franco, Lucia M.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    We report the discovery of nearly coherent oscillations with a frequency of approximately 567 Hz during type I X-ray bursts from the X-ray transient and eclipsing binary X1658-298. If these oscillations are directly related to the neutron star rotation, then the spin period of the neutron star in X1658-298 is approximately 1.8 ms. The oscillations can be present during the rise or decay phase of the bursts. Oscillations during the decay phase of the bursts show an increase in frequency of approximately 0.5-1 Hz. However, in one particular burst the oscillations reappear at the end of the decay phase at about 571.5 Hz. This represents an increase in oscillation frequency of about 5 Hz, which is the largest frequency change seen so far in a burst oscillation. It is unclear if such a large change can be accommodated by present models used to explain the frequency evolution of the oscillations. The oscillations at 571.5 Hz are unusually soft compared to the oscillations found at 567 Hz. We also observed several bursts during which the oscillations are detected at much lower significance or not at all. Most of these bursts happen during periods of X-ray dipping behavior, suggesting that the X-ray dipping might decrease the amplitude of the oscillations (although several complications exist with this simple picture). We discuss our discovery in the framework of the neutron star spin interpretation.

  15. Fully converged integral cross sections of collision induced dissociation, four-center, and single exchange reactions, and accuracy of the centrifugal sudden approximation in H2 + D2 reaction.

    PubMed

    Song, Hongwei; Lu, Yunpeng; Lee, Soo-Y

    2012-03-21

    The initial state selected time-dependent wave packet method was employed to calculate the integral cross sections for the H(2) + D(2) reaction with and without the centrifugal sudden (CS) approximation by including all important K (the projection of the total angular momentum on the body-fixed axis) blocks. With a full-dimensional model, the first fully converged coupled-channel (CC) cross sections for different competitive processes from the ground rotational state were obtained: collision induced dissociation (CID), four-center (4C) reaction and single exchange (SE) reaction. The effect of the total angular momentum J on the reaction dynamics of H(2) + D(2) and the accuracy of the CS approximation have also been studied. It was found that the CID and SE processes occur in a wide range of J values while the 4C process can only take place in a narrow window of J values. For this reason, the CC cross section for the 4C channel is merely comparable to the SE channel. A comparison of the integral cross sections from CC and CS calculations showed that the CS approximation works well for the CID process but not for the 4C and SE processes, and the discrepancy between the CC and CS cross sections grows larger as the translational energy and/or the vibrational energy increase(s).

  16. 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.

  17. OBSERVED BINARY FRACTION SETS LIMITS ON THE EXTENT OF COLLISIONAL GRINDING IN THE KUIPER BELT

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David; Bottke, William F.; Levison, Harold F.; Noll, Keith

    2011-05-15

    The size distribution in the cold classical Kuiper Belt (KB) can be approximated by two idealized power laws: one with steep slope for radii R > R* and one with shallow slope for R < R*, where R* {approx} 25-50 km. Previous works suggested that the size frequency distribution (SFD) rollover at R* can be the result of extensive collisional grinding in the KB that led to the catastrophic disruption of most bodies with R < R*. Here, we use a new code to test the effect of collisions in the KB. We find that the observed rollover could indeed be explained by collisional grinding provided that the initial mass in large bodies was much larger than the one in the present KB and was dynamically depleted. In addition to the size distribution changes, our code also tracks the effects of collisions on binary systems. We find that it is generally easier to dissolve wide binary systems, such as the ones existing in the cold KB today, than to catastrophically disrupt objects with R {approx} R*. Thus, the binary survival sets important limits on the extent of collisional grinding in the KB. We find that the extensive collisional grinding required to produce the SFD rollover at R* would imply a strong gradient of the binary fraction with R and separation, because it is generally easier to dissolve binaries with small components and/or those with wide orbits. The expected binary fraction for R {approx}< R* is {approx}<0.1. The present observational data do not show such a gradient. Instead, they suggest a large binary fraction of {approx}0.4 for R = 30-40 km. This may indicate that the rollover was not produced by disruptive collisions, but is instead a fossil remnant of the KB object formation process.

  18. A Search for Collision Orbits in the Free-Fall Three-Body Problem. I. Numerical Procedure

    NASA Astrophysics Data System (ADS)

    Tanikawa, Kiyotaka; Umehara, Hiroaki; Abe, Hiroshi

    1995-12-01

    A numerical procedure is devised to find binary collision orbits in the free-fall three-body problem. Applying this procedure, families of binary collision orbits are found and a sequence of triple collision orbits are positioned. A property of sets of binary collision orbits which is convenient to search triple collision orbits is found. Important numerical results are formulated and summarized in the final section.

  19. Application of Time Dependent Probabilistic Collision State Checkers in Highly Dynamic Environments

    PubMed Central

    Hernández-Aceituno, Javier; Acosta, Leopoldo; Piñeiro, José D.

    2015-01-01

    When computing the trajectory of an autonomous vehicle, inevitable collision states must be avoided at all costs, so no harm comes to the device or pedestrians around it. In dynamic environments, considering collisions as binary events is risky and inefficient, as the future position of moving obstacles is unknown. We introduce a time-dependent probabilistic collision state checker system, which traces a safe route with a minimum collision probability for a robot. We apply a sequential Bayesian model to calculate approximate predictions of the movement patterns of the obstacles, and define a time-dependent variation of the Dijkstra algorithm to compute statistically safe trajectories through a crowded area. We prove the efficiency of our methods through experimentation, using a self-guided robotic device. PMID:25799557

  20. Scattering from binary optics

    NASA Technical Reports Server (NTRS)

    Ricks, Douglas W.

    1993-01-01

    There are a number of sources of scattering in binary optics: etch depth errors, line edge errors, quantization errors, roughness, and the binary approximation to the ideal surface. These sources of scattering can be systematic (deterministic) or random. In this paper, scattering formulas for both systematic and random errors are derived using Fourier optics. These formulas can be used to explain the results of scattering measurements and computer simulations.

  1. Learning to assign binary weights to binary descriptor

    NASA Astrophysics Data System (ADS)

    Huang, Zhoudi; Wei, Zhenzhong; Zhang, Guangjun

    2016-10-01

    Constructing robust binary local feature descriptors are receiving increasing interest due to their binary nature, which can enable fast processing while requiring significantly less memory than their floating-point competitors. To bridge the performance gap between the binary and floating-point descriptors without increasing the computational cost of computing and matching, optimal binary weights are learning to assign to binary descriptor for considering each bit might contribute differently to the distinctiveness and robustness. Technically, a large-scale regularized optimization method is applied to learn float weights for each bit of the binary descriptor. Furthermore, binary approximation for the float weights is performed by utilizing an efficient alternatively greedy strategy, which can significantly improve the discriminative power while preserve fast matching advantage. Extensive experimental results on two challenging datasets (Brown dataset and Oxford dataset) demonstrate the effectiveness and efficiency of the proposed method.

  2. Solar System binaries

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    The discovery of binaries in each of the major populations of minor bodies in the solar system is propelling a rapid growth of heretofore unattainable physical information. The availability of mass and density constraints for minor bodies opens the door to studies of internal structure, comparisons with meteorite samples, and correlations between bulk-physical and surface-spectral properties. The number of known binaries is now more than 70 and is growing rapidly. A smaller number have had the extensive followup observations needed to derive mass and albedo information, but this list is growing as well. It will soon be the case that we will know more about the physical parameters of objects in the Kuiper Belt than has been known about asteroids in the Main Belt for the last 200 years. Another important aspect of binaries is understanding the mechanisms that lead to their formation and survival. The relative sizes and separations of binaries in the different minor body populations point to more than one mechanism for forming bound pairs. Collisions appear to play a major role in the Main Belt. Rotational and/or tidal fission may be important in the Near Earth population. For the Kuiper Belt, capture in multi-body interactions may be the preferred formation mechanism. However, all of these conclusions remain tentative and limited by observational and theoretical incompleteness. Observational techniques for identifying binaries are equally varied. High angular resolution observations from space and from the ground are critical for detection of the relatively distant binaries in the Main Belt and the Kuiper Belt. Radar has been the most productive method for detection of Near Earth binaries. Lightcurve analysis is an independent technique that is capable of exploring phase space inaccessible to direct observations. Finally, spacecraft flybys have played a crucial paradigm-changing role with discoveries that unlocked this now-burgeoning field.

  3. 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.

  4. 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

  5. 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.

  6. Binary Plutinos

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    2015-08-01

    The Pluto-Charon binary was the first trans-neptunian binary to be identified in 1978. Pluto-Charon is a true binary with both components orbiting a barycenter located between them. The Pluto system is also the first, and to date only, known binary with a satellite system consisting of four small satellites in near-resonant orbits around the common center of mass. Seven other Plutinos, objects in 3:2 mean motion resonance with Neptune, have orbital companions including 2004 KB19 reported here for the first time. Compared to the Cold Classical population, the Plutinos differ in the frequency of binaries, the relative sizes of the components, and their inclination distribution. These differences point to distinct dynamical histories and binary formation processes encountered by Plutinos.

  7. Temperature-Induced Coalescence of Colliding Binary Droplets on Superhydrophobic Surface

    PubMed Central

    Yi, Nan; Huang, Bin; Dong, Lining; Quan, Xiaojun; Hong, Fangjun; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2014-01-01

    This report investigates the impact of droplet temperature on the head-on collision of binary droplets on a superhydrophobic surface. Understanding droplet collision is critical to many fundamental processes and industrial applications. There are many factors, including collision speed, collision angle, and droplet composition, that influence the outcome of the collision between binary droplets. This work provides the first experimental study of the influence of droplet temperature on the collision of binary droplets. As the droplet temperature increases, the possibility increases for the two droplets to coalesce after collision. The findings in this study can be extended to collision of droplets under other conditions where control of the droplet temperature is feasible. Such findings will also be beneficial to applications that involve droplet collision, such as in ink-jet printing, steam turbines, engine ignition, and spraying cooling. PMID:24603362

  8. Temperature-Induced Coalescence of Colliding Binary Droplets on Superhydrophobic Surface

    NASA Astrophysics Data System (ADS)

    Yi, Nan; Huang, Bin; Dong, Lining; Quan, Xiaojun; Hong, Fangjun; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2014-03-01

    This report investigates the impact of droplet temperature on the head-on collision of binary droplets on a superhydrophobic surface. Understanding droplet collision is critical to many fundamental processes and industrial applications. There are many factors, including collision speed, collision angle, and droplet composition, that influence the outcome of the collision between binary droplets. This work provides the first experimental study of the influence of droplet temperature on the collision of binary droplets. As the droplet temperature increases, the possibility increases for the two droplets to coalesce after collision. The findings in this study can be extended to collision of droplets under other conditions where control of the droplet temperature is feasible. Such findings will also be beneficial to applications that involve droplet collision, such as in ink-jet printing, steam turbines, engine ignition, and spraying cooling.

  9. Temperature-induced coalescence of colliding binary droplets on superhydrophobic surface.

    PubMed

    Yi, Nan; Huang, Bin; Dong, Lining; Quan, Xiaojun; Hong, Fangjun; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2014-03-07

    This report investigates the impact of droplet temperature on the head-on collision of binary droplets on a superhydrophobic surface. Understanding droplet collision is critical to many fundamental processes and industrial applications. There are many factors, including collision speed, collision angle, and droplet composition, that influence the outcome of the collision between binary droplets. This work provides the first experimental study of the influence of droplet temperature on the collision of binary droplets. As the droplet temperature increases, the possibility increases for the two droplets to coalesce after collision. The findings in this study can be extended to collision of droplets under other conditions where control of the droplet temperature is feasible. Such findings will also be beneficial to applications that involve droplet collision, such as in ink-jet printing, steam turbines, engine ignition, and spraying cooling.

  10. Identification list of binaries

    NASA Astrophysics Data System (ADS)

    Malkov,, O.; Karchevsky,, A.; Kaygorodov, P.; Kovaleva, D.

    The Identification List of Binaries (ILB) is a star catalogue constructed to facilitate cross-referencing between different catalogues of binary stars. As of 2015, it comprises designations for approximately 120,000 double/multiple systems. ILB contains star coordinates and cross-references to the Bayer/Flemsteed, DM (BD/CD/CPD), HD, HIP, ADS, WDS, CCDM, TDSC, GCVS, SBC9, IGR (and some other X-ray catalogues), PSR designations, as well as identifications in the recently developed BSDB system. ILB eventually became a part of the BDB stellar database.

  11. Systematic approach for simultaneously correcting the band-gap andp-dseparation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

    SciTech Connect

    Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

    2015-07-31

    We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X = N,P,As,Sb, and II-VI compounds, (Zn or Cd)X, with X = O,S,Se,Te. By correcting (1) the binary band gaps at high-symmetry points , L, X, (2) the separation of p-and d-orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles method can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.

  12. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars.

  13. Kinetic Models with Randomly Perturbed Binary Collisions

    NASA Astrophysics Data System (ADS)

    Bassetti, Federico; Ladelli, Lucia; Toscani, Giuseppe

    2011-02-01

    We introduce a class of Kac-like kinetic equations on the real line, with general random collisional rules which, in some special cases, identify models for granular gases with a background heat bath (Carrillo et al. in Discrete Contin. Dyn. Syst. 24(1):59-81, 2009), and models for wealth redistribution in an agent-based market (Bisi et al. in Commun. Math. Sci. 7:901-916, 2009). Conditions on these collisional rules which guarantee both the existence and uniqueness of equilibrium profiles and their main properties are found. The characterization of these stationary states is of independent interest, since we show that they are stationary solutions of different evolution problems, both in the kinetic theory of rarefied gases (Cercignani et al. in J. Stat. Phys. 105:337-352, 2001; Villani in J. Stat. Phys. 124:781-822, 2006) and in the econophysical context (Bisi et al. in Commun. Math. Sci. 7:901-916, 2009).

  14. Approximation algorithms

    PubMed Central

    Schulz, Andreas S.; Shmoys, David B.; Williamson, David P.

    1997-01-01

    Increasing global competition, rapidly changing markets, and greater consumer awareness have altered the way in which corporations do business. To become more efficient, many industries have sought to model some operational aspects by gigantic optimization problems. It is not atypical to encounter models that capture 106 separate “yes” or “no” decisions to be made. Although one could, in principle, try all 2106 possible solutions to find the optimal one, such a method would be impractically slow. Unfortunately, for most of these models, no algorithms are known that find optimal solutions with reasonable computation times. Typically, industry must rely on solutions of unguaranteed quality that are constructed in an ad hoc manner. Fortunately, for some of these models there are good approximation algorithms: algorithms that produce solutions quickly that are provably close to optimal. Over the past 6 years, there has been a sequence of major breakthroughs in our understanding of the design of approximation algorithms and of limits to obtaining such performance guarantees; this area has been one of the most flourishing areas of discrete mathematics and theoretical computer science. PMID:9370525

  15. Modified evolution of stellar binaries from supermassive black hole binaries

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Wang, Yi-Han; Yuan, Ye-Fei

    2017-04-01

    The evolution of main-sequence binaries resided in the galactic centre is influenced a lot by the central supermassive black hole (SMBH). Due to this perturbation, the stars in a dense environment are likely to experience mergers or collisions through secular or non-secular interactions. In this work, we study the dynamics of the stellar binaries at galactic centre, perturbed by another distant SMBH. Geometrically, such a four-body system is supposed to be decomposed into the inner triple (SMBH-star-star) and the outer triple (SMBH-stellar binary-SMBH). We survey the parameter space and determine the criteria analytically for the stellar mergers and the tidal disruption events (TDEs). For a relative distant and equal masses SMBH binary, the stars have more opportunities to merge as a result from the Lidov-Kozai (LK) oscillations in the inner triple. With a sample of tight stellar binaries, our numerical experiments reveal that a significant fraction of the binaries, ∼70 per cent, experience merger eventually. Whereas the majority of the stellar TDEs are likely to occur at a close periapses to the SMBH, induced by the outer Kozai effect. The tidal disruptions are found numerically as many as ∼10 per cent for a close SMBH binary that is enhanced significantly than the one without the external SMBH. These effects require the outer perturber to have an inclined orbit (≥40°) relatively to the inner orbital plane and may lead to a burst of the extremely astronomical events associated with the detection of the SMBH binary.

  16. 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.

  17. NEA rotations and binaries

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Harris, A. W.; Warner, B. D.

    2007-05-01

    Of nearly 3900 near-Earth asteroids known in June 2006, 325 have got estimated rotation periods. NEAs with sizes down to 10 meters have been sampled. Observed spin distribution shows a major changing point around D=200 m. Larger NEAs show a barrier against spin rates >11 d-1 (period P~2.2 h) that shifts to slower rates with increasing equatorial elongation. The spin barrier is interpreted as a critical spin rate for bodies held together by self-gravitation only, suggesting that NEAs larger than 200 m are mostly strenghtless bodies (i.e., with zero tensile strength), so called `rubble piles'. The barrier disappears at D<200 m where most objects rotate too fast to be held together by self-gravitation only, so a non-zero cohesion is implied in the smaller NEAs. The distribution of NEA spin rates in the `rubble pile' range (D>0.2 km) is non-Maxwellian, suggesting that other mechanisms than just collisions worked there. There is a pile up in front of the barrier (P of 2-3 h). It may be related to a spin up mechanism crowding asteroids to the barrier. An excess of slow rotators is seen at P>30 h. The spin-down mechanism has no clear lower limit on spin rate; periods as long as tens of days occur. Most NEAs appear to be in basic spin states with rotation around the principal axis. Excited rotations are present among and actually dominate in slow rotators with damping timescales >4.5 byr. A few tumblers observed among fast rotating coherent objects consistently appear to be more rigid or younger than the larger, rubble-pile tumblers. An abundant population of binary systems among NEAs has been found. The fraction of binaries among NEAs larger than 0.3 km has been estimated to be 15 +/-4%. Primaries of the binary systems concentrate at fast spin rates (periods 2-3 h) and low amplitudes, i.e., they lie just below the spin barrier. The total angular momentum content in the binary systems suggests that they formed at the critical spin rate, and that little or no angular

  18. Asteroid Systems: Binaries, Triples, and Pairs

    NASA Astrophysics Data System (ADS)

    Margot, J.-L.; Pravec, P.; Taylor, P.; Carry, B.; Jacobson, S.

    In the past decade, the number of known binary near-Earth asteroids has more than quadrupled and the number of known large main-belt asteroids with satellites has doubled. Half a dozen triple asteroids have been discovered, and the previously unrecognized populations of asteroid pairs and small main-belt binaries have been identified. The current observational evidence confirms that small (≲20 km) binaries form by rotational fission and establishes that the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect powers the spin-up process. A unifying paradigm based on rotational fission and post-fission dynamics can explain the formation of small binaries, triples, and pairs. Large (>~20 km) binaries with small satellites are most likely created during large collisions.

  19. Modeling defect production in high energy collision cascades

    SciTech Connect

    Heinisch, H.L.; Singh, B.N.; Diaz de la Rubia, T.

    1993-12-01

    A multi-model approach roach (MMA) to simulating defect production processes at the atomic scale is described that incorporates molecular dynamics (MD), binary collision approximation (BCA) calculations and stochastic annealing simulations. The central hypothesis of the MMA is that the simple, fast computer codes capable of simulating large numbers of high energy cascades (e.g., BCA codes) can be made to yield the correct defect configurations when their parameters are calibrated using the results of the more physically realistic MD simulations. The calibration procedure is investigated using results of MD simulations of 25 keV cascades in copper. The configurations of point defects are extracted from the MD cascade simulations at the end of the collisional phase, similar to the information obtained with a binary collision model. The MD collisional phase defect configurations are used as input to the ALSOME annealing simulation code, and values of the ALSOME quenching parameters are determined that yield the best fit to the post-quenching defect configurations of the MD simulations.

  20. Bethe binary-encounter peaks in the double-differential cross sections for high-energy electron-impact ionization of H2 and He

    NASA Astrophysics Data System (ADS)

    Chatterjee, S.; Agnihotri, A. N.; Stia, C. R.; Fojón, O. A.; Rivarola, R. D.; Tribedi, L. C.

    2010-11-01

    We study the Bethe binary-encounter (BE) region in the ejected-electron double-differential emission spectrum of H2 and He targets in collisions with 8-keV electrons. We compare the absolute cross sections for these isoelectronic systems at high emission energies. The experimental data are analyzed in terms of a state-of-the-art theoretical model based on a two-effective-center approximation. In the case of the H2 molecule the binary peak in the double-differential cross sections (DDCS) is enhanced due to the two-center Young-type interference. The observed undulation in the DDCS ratio is explained in terms of the combined contributions of the Compton profile mismatch and the interference effect. The influence of the interference effect is thus observed for higher-energy electrons compared to most of the earlier studies which focused on low-energy electrons produced in soft collisions.

  1. Bethe binary-encounter peaks in the double-differential cross sections for high-energy electron-impact ionization of H{sub 2} and He

    SciTech Connect

    Chatterjee, S.; Agnihotri, A. N.; Tribedi, L. C.; Stia, C. R.; Fojon, O. A.; Rivarola, R. D.

    2010-11-15

    We study the Bethe binary-encounter (BE) region in the ejected-electron double-differential emission spectrum of H{sub 2} and He targets in collisions with 8-keV electrons. We compare the absolute cross sections for these isoelectronic systems at high emission energies. The experimental data are analyzed in terms of a state-of-the-art theoretical model based on a two-effective-center approximation. In the case of the H{sub 2} molecule the binary peak in the double-differential cross sections (DDCS) is enhanced due to the two-center Young-type interference. The observed undulation in the DDCS ratio is explained in terms of the combined contributions of the Compton profile mismatch and the interference effect. The influence of the interference effect is thus observed for higher-energy electrons compared to most of the earlier studies which focused on low-energy electrons produced in soft collisions.

  2. 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.

  3. A Monte Carlo model for determination of binary diffusion coefficients in gases

    SciTech Connect

    Panarese, A.; Bruno, D.; Colonna, G.; Diomede, P.; Laricchiuta, A.; Longo, S.; Capitelli, M.

    2011-06-20

    A Monte Carlo method has been developed for the calculation of binary diffusion coefficients in gas mixtures. The method is based on the stochastic solution of the linear Boltzmann equation obtained for the transport of one component in a thermal bath of the second one. Anisotropic scattering is included by calculating the classical deflection angle in binary collisions under isotropic potential. Model results are compared to accurate solutions of the Chapman-Enskog equation in the first and higher orders. We have selected two different cases, H{sub 2} in H{sub 2} and O in O{sub 2}, assuming rigid spheres or using a model phenomenological potential. Diffusion coefficients, calculated in the proposed approach, are found in close agreement with Chapman-Enskog results in all the cases considered, the deviations being reduced using higher order approximations.

  4. First known Terrestrial Impact of a Binary Asteroid from a Main Belt Breakup Event

    PubMed Central

    Ormö, Jens; Sturkell, Erik; Alwmark, Carl; Melosh, Jay

    2014-01-01

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably ‘rubble pile’ asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids. PMID:25340551

  5. First known terrestrial impact of a binary asteroid from a main belt breakup event.

    PubMed

    Ormö, Jens; Sturkell, Erik; Alwmark, Carl; Melosh, Jay

    2014-10-23

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably 'rubble pile' asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids.

  6. DSMC simulation of Rayleigh-Brillouin scattering in binary mixtures

    NASA Astrophysics Data System (ADS)

    Bruno, Domenico; Frezzotti, Aldo; Ghiroldi, Gian Pietro

    2016-11-01

    Rayleigh-Brillouin scattering spectra (RBS) in dilute gas mixtures have been simulated by the Direct Simulation Monte Carlo method (DSMC). Different noble gas binary mixtures have been considered and the spectra have been simulated adopting the hard sphere collision model. It is suggested that DSMC simulations can be used in the interpretation of light scattering experiments in place of approximate kinetic models. Actually, the former have a firmer physical ground and can be readily extended to treat gas mixtures of arbitrary complexity. The results obtained confirm the capability of DSMC to predict experimental spectra and clears the way towards the simulation of polyatomic gas mixtures of interest for actual application (notably, air) where tractable kinetic model equations are still lacking.

  7. Total Born approximation cross sections for single electron loss by atoms and ions colliding with atoms

    NASA Technical Reports Server (NTRS)

    Rule, D. W.

    1977-01-01

    The first born approximation (FBA) is applied to the calculation of single electron loss cross sections for various ions and atoms containing from one to seven electrons. Screened hydrogenic wave functions were used for the states of the electron ejected from the projectile, and Hartree-Fock elastic and incoherent scattering factors were used to describe the target. The effect of the target atom on the scaling of projectile ionization cross sections with respect to the projectile nuclear charge was explored in the case of hydrogen-like ions. Scaling of the cross section with respect to the target nuclear charge for electron loss by Fe (+25) in collision with neutral atoms ranging from H to Fe is also examined. These results were compared to those of the binary encounter approximation and to the FBA for the case of ionization by completely stripped target ions.

  8. NEAs' Binaries and Planetary Close Encounters -Stability and Lifetime

    NASA Astrophysics Data System (ADS)

    Araujo, Rosana; Winter, O.

    2013-05-01

    Abstract (2,250 Maximum Characters): In the present work we considered the effects of close encounters, suffered by hypothetical NEAs binaries, with Earth, Mercury and Venus, in order to determine the stability of their satellites as a function of the encounter conditions. In addition, knowing the conditions that leads to the loss (by ejection or collisions) of the most internal satellites, we are able to estimate the frequency of such encounters, and thus, determine the expected lifetime of the NEAs binaries. The methodology consisted on numerically simulate a system composed by the Sun, the planets of the Solar System, and a sample of 2100 NEAs, for a period of 10 Myr (predict NEAs' lifetime). All close encounters with the planets closer than 100 planet's radius were registered. The next step consisted on simulate a representative sample of those registered close encounters, through numerical integration, considering the planet, the asteroid that perform the close encounter, and a cloud of satellites around the asteroid. The largest radial distance for which all the satellites survive (no collision or ejection) was defined as the critical radius - Rc, given as a function of the encounter parameters (relative velocity and impact parameter). For the Earth, we found that the close encounters with impact parameter and relative velocity capable to remove the most internal satellites of the NEAs (Rc < 5 km), are very frequent. We found that 93% of the asteroids of the group Atens suffer an encounter within this limit in 10 Myrs, and that 50% of these encounters happen in approximately 330.000 years. For the Apollos we found that 60% of the asteroids suffer such encounters, and that 50% of then happen in approximately 700.000 years. Such results indicate that, in fact, the lifetime of the binaries is strongly influencied by the planetary close encounters, proving to be significantly shorter than the predicted lifetime of the NEAs. The contribution of the planets Mercury

  9. Astrometric Binaries: White Dwarfs?

    NASA Astrophysics Data System (ADS)

    Oliversen, Nancy A.

    We propose to observe a selection of astrometric or spectroscopicastrometric binaries nearer than about 20 pc with unseen low mass companions. Systems of this type are important for determining the luminosity function of low mass stars (white dwarfs and very late main sequence M stars), and their contribution to the total mass of the galaxy. Systems of this type are also important because the low mass, invisible companions are potential candidates in the search for planets. Our target list is selected primarily from the list of 31 astrometric binaries near the sun by Lippincott (1978, Space Sci. Rev., 22, 153), with additional candidates from recent observations by Kamper. The elimination of stars with previous IUE observations, red companions resolved by infrared speckle interferometry, or primaries later than M1 (because if white dwarf companions are present they should have been detected in the visible region) reduces the list to 5 targets which need further information. IUE SWP low dispersion observations of these targets will show clearly whether the remaining unseen companions are white dwarfs, thus eliminating very cool main sequence stars or planets. This is also important in providing complete statistical information about the nearest stars. The discovery of a white dwarf in such a nearby system would provide important additional information about the masses of white dwarfs. Recent results by Greenstein (1986, A. J., 92, 859) from binary systems containing white dwarfs imply that 80% of such systems are as yet undetected. The preference of binaries for companions of approximately equal mass makes the Lippincott-Kamper list of A through K primaries with unseen companions a good one to use to search for white dwarfs. The mass and light dominance of the current primary over the white dwarf in the visible makes ultraviolet observations essential to obtain an accurate census of white dwarf binaries.

  10. Binary Formation in Planetesimal Disks. I. Equal Mass Planetesimals

    NASA Astrophysics Data System (ADS)

    Kominami, Junko D.; Makino, Junichiro; Daisaka, Hiroshi

    2011-12-01

    As of April 2010, 48 TNO (trans-Neptunian Object) binaries have been found. This is about 6% of known TNOs. However, in previous theoretical studies of planetary formation in the TNO region, the effect of binary formation has been neglected. TNO binaries can be formed through a variety of mechanisms, such as a three-body process, dynamical friction on two massive bodies, inelastic collisions between two bodies etc. Most of these mechanisms become more effective as the distance from the Sun increases. In this paper, we describe our study on three-body process using direct N-body simulations. We found that chaos-assisted-capture (CAC) is the dominant channel of binary formation. We systematically changed the distance from the Sun, the number density of planetesimals, and the radius of the planetesimals and studied the effect of the binaries on the collision rate of planetesimals. In the TNO region, binaries are involved in 1/3-1/2 of collisions, and the collision rate increases by a factor of a few compared to the theoretical estimate for direct two-body collisions. Thus, it is possible that the binaries significantly enhance the collision rate and reduce the growth timescale. In the terrestrial planet region, binaries are less important, because the ratio between the Hill radius and the physical size of the planetesimals is relatively small. Although the time scale of our simulations is short, they clearly demonstrated that the accretion process in the TNO region is quite different from that in the terrestrial planet region.

  11. Kinetic theory of binary particles with unequal mean velocities and non-equipartition energies

    NASA Astrophysics Data System (ADS)

    Chen, Yanpei; Mei, Yifeng; Wang, Wei

    2017-03-01

    The hydrodynamic conservation equations and constitutive relations for a binary granular mixture composed of smooth, nearly elastic spheres with non-equipartition energies and different mean velocities are derived. This research is aimed to build three-dimensional kinetic theory to characterize the behaviors of two species of particles suffering different forces. The standard Enskog method is employed assuming a Maxwell velocity distribution for each species of particles. The collision components of the stress tensor and the other parameters are calculated from the zeroth- and first-order approximation. Our results demonstrate that three factors, namely the differences between two granular masses, temperatures and mean velocities all play important roles in the stress-strain relation of the binary mixture, indicating that the assumption of energy equipartition and the same mean velocity may not be acceptable. The collision frequency and the solid viscosity increase monotonously with each granular temperature. The zeroth-order approximation to the energy dissipation varies greatly with the mean velocities of both species of spheres, reaching its peak value at the maximum of their relative velocity.

  12. The Lockne - Målingen doublet impacts, the result of a binary asteroid from the 470 Ma Main Asteroid Belt event

    NASA Astrophysics Data System (ADS)

    Sturkell, E. C.; Ormo, J.; Alwmark, C.; Melosh, H., IV

    2015-12-01

    Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt (MAB), which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. The 600 m large Lockne asteroid was a binary and had a companion in space by a smaller 150 m satellite. The recent discovery of the nearby, 0.7-km diameter, synchronous Målingen crater suggests it to form a doublet impact structure together with the larger Lockne crater, and as we will show here, most likely by a binary, 'rubble pile' asteroid. Despite observational evidence that about 16% of the Near Earth Asteroids (NEA's) are binary, only a handful of the approximately 188 known craters on Earth have been suggested as potential doublets. The stratigraphic and geographic relationship with Lockne suggests the Lockne and Målingen craters to be the first described doublet impact structure by a binary asteroid into a marine-target setting. In addition, the precise dating of the Lockne-Målingen impact in relation to the MAB breakup event provides a hands-on reference for studies of the formation of binaries from asteroid breakup events.

  13. Studies of Fluctuation Processes in Nuclear Collisions

    SciTech Connect

    Ayik, Sakir

    2016-04-14

    The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and

  14. The Binary Mass Transfer Origin of the Red Blue Straggler Sequence in M30

    NASA Astrophysics Data System (ADS)

    Xin, Y.; Ferraro, F. R.; Lu, P.; Deng, L.; Lanzoni, B.; Dalessandro, E.; Beccari, G.

    2015-03-01

    Two separated sequences of blue straggler stars (BSSs) have been revealed by Ferraro et al. in the color-magnitude diagram (CMD) of the Milky Way globular cluster M30. Their presence has been suggested to be related to the two BSS formation channels (namely, collisions and mass transfer in close binaries) operating within the same stellar system. The blue sequence was indeed found to be well reproduced by collisional BSS models. In contrast, no specific models for mass-transfer BSSs were available for an old stellar system like M30. Here we present binary evolution models, including case-B mass transfer and binary merging, specifically calculated for this cluster. We discuss in detail the evolutionary track of a 0.9 + 0.5 M ⊙ binary, which spends approximately 4 Gyr in the BSS region of the CMD of a 13 Gyr old cluster. We also run Monte Carlo simulations to study the distribution of mass-transfer BSSs in the CMD and to compare it with the observational data. Our results show that (1) the color and magnitude distribution of synthetic mass-transfer BSSs defines a strip in the CMD that nicely matches the observed red-BSS sequence, thus providing strong support to the mass-transfer origin for these stars; (2) the CMD distribution of synthetic BSSs never attains the observed location of the blue-BSS sequence, thus reinforcing the hypothesis that the latter formed through a different channel (likely collisions); (3) most (~60%) of the synthetic BSSs are produced by mass-transfer models, while the remaining <40% requires the contribution from merger models.

  15. Identified baryon and meson distributions at large transverse momenta from Au + Au collisions at square root sNN=200 GeV.

    PubMed

    Abelev, B I; Aggarwal, M M; Ahammed, Z; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellingeri-Laurikainen, A; Bellwied, R; Benedosso, F; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, S-L; Bonner, B E; Botje, M; Bouchet, J; Brandin, A V; Bravar, A; Burton, T P; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Castillo, J; Catu, O; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Das, S; Dash, S; Daugherity, M; de Moura, M M; Dedovich, T G; Dephillips, M; Derevschikov, A A; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, W J; Dong, X; Draper, J E; Du, F; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Fatemi, R; Fedorisin, J; Filip, P; Finch, E; Fine, V; Fisyak, Y; Fu, J; Gagliardi, C A; Gaillard, L; Ganti, M S; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Gorbunov, Y G; Gos, H; Grebenyuk, O; Grosnick, D; Guertin, S M; Guimaraes, K S F F; Gupta, N; Gutierrez, T D; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Hepplemann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffman, A M; Hoffmann, G W; Horner, M J; Huang, H Z; Huang, S L; Hughes, E W; Humanic, T J; Igo, G; Jacobs, P; Jacobs, W W; Jakl, P; Jia, F; Jiang, H; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Khodyrev, V Yu; Kim, B C; Kiryluk, J; Kisiel, A; Kislov, E M; Klein, S R; Kocoloski, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lapointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lehocka, S; Levine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lin, X; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Liu, Z; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Magestro, D; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Melnick, Yu; Meschanin, A; Millane, J; Miller, M L; Minaev, N G; Mioduszewski, S; Mironov, C; Mischke, A; Mishra, D K; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Nepali, N S; Netrakanti, P K; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Poljak, N; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rakness, G; Raniwala, R; Raniwala, S; Ray, R L; Razin, S V; Reinnarth, J; Relyea, D; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shen, W Q; Shimanskiy, S S; Sichtermann, E P; Simon, F; Singaraju, R N; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Suaide, A A P; Subba, N L; Sugarbaker, E; Sumbera, M; Sun, Z; Surrow, B; Swanger, M; Symons, T J M; Szanto de Toledo, A; Tai, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thein, D; Thomas, J H; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van der Kolk, N; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, X L; Wang, Y; Watson, J W; Webb, J C; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yurevich, V I; Zhan, W; Zhang, H; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N; Zuo, J X

    2006-10-13

    Transverse momentum spectra of pi+/-, p, and p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at square root sNN=200 GeV are presented. In central Au + Au collisions, both pi +/- and p(p) show significant suppression with respect to binary scaling at pT approximately >4 GeV/c. Protons and antiprotons are less suppressed than pi+/-, in the range 1.5 approximately < pT approximately < 6 GeV/c. The pi-/pi+ and p/p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at pT approximately >5 GeV/c. The results at high pT indicate that the partonic sources of pi+/-, p, and p have similar energy loss when traversing the nuclear medium.

  16. 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

  17. 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.

  18. Approximation methods in gravitational-radiation theory

    NASA Astrophysics Data System (ADS)

    Will, C. M.

    1986-02-01

    The observation of gravitational-radiation damping in the binary pulsar PSR 1913+16 and the ongoing experimental search for gravitational waves of extraterrestrial origin have made the theory of gravitational radiation an active branch of classical general relativity. In calculations of gravitational radiation, approximation methods play a crucial role. The author summarizes recent developments in two areas in which approximations are important: (1) the quadrupole approximation, which determines the energy flux and the radiation reaction forces in weak-field, slow-motion, source-within-the-near-zone systems such as the binary pulsar; and (2) the normal modes of oscillation of black holes, where the Wentzel-Kramers-Brillouin approximation gives accurate estimates of the complex frequencies of the modes.

  19. STAR HOPPERS: PLANET INSTABILITY AND CAPTURE IN EVOLVING BINARY SYSTEMS

    SciTech Connect

    Kratter, Kaitlin M.; Perets, Hagai B.

    2012-07-01

    Many planets are observed in stellar binary systems, and their frequency may be comparable to that of planetary systems around single stars. Binary stellar evolution in such systems influences the dynamical evolution of the resident planets. Here, we study the evolution of a single planet orbiting one star in an evolving binary system. We find that stellar evolution can trigger dynamical instabilities that drive planets into chaotic orbits. This instability leads to planet-star collisions, exchange of the planet between the binary stars ('star hoppers'), and ejection of the planet from the system. The means by which planets can be recaptured is similar to the pull-down capture mechanism for irregular solar system satellites. Because planets often suffer close encounters with the primary on the asymptotic giant branch, captures during a collision with the stellar envelope are also possible for more massive planets. Such capture could populate the habitable zone around white dwarfs.

  20. 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.

  1. Quickly Approximating the Distance Between Two Objects

    NASA Technical Reports Server (NTRS)

    Hammen, David

    2009-01-01

    A method of quickly approximating the distance between two objects (one smaller, regarded as a point; the other larger and complexly shaped) has been devised for use in computationally simulating motions of the objects for the purpose of planning the motions to prevent collisions.

  2. The Binary Temperature-Composition Phase Diagram

    ERIC Educational Resources Information Center

    Sanders, Philip C.; Reeves, James H.; Messina, Michael

    2006-01-01

    The equations for the liquid and gas lines in the binary temperature-composition phase diagram are derived by approximating that delta(H)[subscript vap] of the two liquids are equal. It is shown that within this approximation, the resulting equations are not too difficult to present in an undergraduate physical chemistry lecture.

  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. TOPICAL REVIEW: Coalescing binary neutron stars

    NASA Astrophysics Data System (ADS)

    Rasio, Frederic A.; Shapiro, Stuart L.

    1999-06-01

    Coalescing compact binaries with neutron star or black hole components provide the most promising sources of gravitational radiation for detection by the LIGO/VIRGO/GEO/TAMA laser interferometers now under construction. This fact has motivated several different theoretical studies of the inspiral and hydrodynamic merging of compact binaries. Analytic analyses of the inspiral waveforms have been performed in the post-Newtonian approximation. Analytic and numerical treatments of the coalescence waveforms from binary neutron stars have been performed using Newtonian hydrodynamics and the quadrupole radiation approximation. Numerical simulations of coalescing black hole and neutron star binaries are also underway in full general relativity. Recent results from each of these approaches will be described and their virtues and limitations summarized.

  5. Electron excitation after plasmon decay in proton-aluminum collisions

    SciTech Connect

    Bocan, G.; Miraglia, J.E.

    2003-03-01

    When a projectile travels inside a metal, it interacts with the electron gas, producing both binary and collective excitations (plasmons). Within the nearly-free-electron-gas scheme, Roesler and co-workers showed that plasmons decay in first order and a conduction electron is emitted (interband transition). Working within the frame of atomic collisions, we develop a simple model to describe this decay. The first-order Born expansion is used to approximate the electron wave functions. The influence of the lattice potential on the excited electron is considered in the calculations in order to balance the momentum-conservation equation. It gives contributions associated with sites of the reciprocal lattice. The potential expansion coefficients are obtained following Animalu and co-workers [Philos. Mag. 9, 451 (1964)]. First- and second-differential spectra (in energy and angle) are analyzed discriminating contributions due to different lattice momenta. In all cases, contributions due to binary excitations of the valence electrons and inner-shell ionization are presented to establish a comparison.

  6. A binary star fraction of 76 per cent and unusual orbit parameters for the blue stragglers of NGC 188.

    PubMed

    Mathieu, Robert D; Geller, Aaron M

    2009-12-24

    Blue straggler stars lie on or near the main sequences of star clusters (all members of which formed around the same time), but typically are more luminous than the turn-off stars and therefore long ago should have evolved off the main sequence to become giants and white dwarfs. They are thought to derive from normal main-sequence stars that have undergone a recent increase in mass. Statistical evidence indicates that in globular star clusters the blue stragglers probably form from binary stars. The specific formation processes, such as mass transfer, mergers or stellar collisions during dynamical encounters of binary stars, remain unresolved. Here we report that 16 of the 21 blue stragglers (76 per cent) in the old (7-Gyr; ref. 2) open cluster NGC 188 are currently in binary systems, a frequency three times that found among normal solar-type main-sequence stars. These blue straggler binaries have a remarkable period-eccentricity distribution, with all but three having orbital periods of approximately 1,000 days. Moreover, these stars are rotating faster than normal main-sequence stars of the same surface temperatures. These data show that most, and possibly all, blue stragglers derive from multiple-star systems, and indicate that the several formation processes operate simultaneously. We suggest that rapid rotation of blue stragglers may place upper limits on their ages.

  7. Widths and Shifts of Isolated Lines of Neutral and Ionized Atoms Perturbed by Collisions With Electrons and Ions: An Outline of the Semiclassical Perturbation (SCP) Method and of the Approximations Used for the Calculations

    NASA Astrophysics Data System (ADS)

    Sahal-Bréchot, Sylvie; Dimitrijević, Milan; Nessib, Nabil

    2014-06-01

    "Stark broadening" theory and calculations have been extensively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modeling, in astrophysics, laboratory plasma physics and technological plasmas, as well. This requires the knowledge of numerous collisional line profiles. In order to meet these needs, the "SCP" (semiclassical perturbation) method and numerical code were created and developed. The SCP code is now extensively used for the needs of spectroscopic diagnostics and modeling, and the results of the published calculations are displayed in the STARK-B database. The aim of the present paper is to introduce the main approximations leading to the impact of semiclassical perturbation method and to give formulae entering the numerical SCP code, in order to understand the validity conditions of the method and of the results; and also to understand some regularities and systematic trends. This would also allow one to compare the method and its results to those of other methods and codes.

  8. Convoy electron production in heavy-ion-solid collisions

    SciTech Connect

    Sellin, I.A.; Breinig, M.; Brandt, W.; Laubert, R.

    1981-01-01

    The properties of the sharp v vector/sub e/ approx. = v vector cusps observed in the velocity spectrum of convoy electrons (v vector/sub e/) ejected in heavy ion-solid collisions in the ion velocity range (v vector) 6 to 18 au are compared to the properties of analogous cusps observed in binary electron capture to the continuum (ECC) and electron loss to the continuum (ELC) collisions in gases. Apart from a skew toward v vector/sub e/ > v vector, the v-independent convoy distributions observed are very similar to those for ELC and the cusp widths are the same in both cases. While the shape of convoy peaks is approximately independent of projectile Z, v, and of target material, yields in polycrystalline targets (C, Al, Ag, Au) exhibit a strong dependence on Z and v. Coincidence experiments in which convoy electrons are allocated according to emergent ion charge-state q/sub e/ show a surprising independence of q/sub e/, mirroring the unweighted statistical emergent charge-state fraction. Coincidence experiments of O/sup 6 +/ /sup 7 +/ /sup 8 +/ ions traversing < 110 > and < 100 > channels in Au show a strong yield suppression and a dependence of yield on the channel chosen. Interpretation of these observations, comparisons to convoy production studies using protons, and a discussion of remaining puzzles is given. The history of ECC, ELC, and wake-riding models of convoy electron production is also reviewed.

  9. Approximate formula for recalescence in binary eutectic alloys

    NASA Technical Reports Server (NTRS)

    Ohsaka, K.; Trinh, E. H.

    1993-01-01

    Supercooling of a liquid prior to the nucleation of a solid and the subsequent rapid growth are necessary conditions for producing novel microstructures including metastable phases which are not formed by conventional solidification processes. Since containerless techniques, such as levitation and free fall of a sample, are capable of achieving a significant supercooling level of liquids, they are under consideration as possible techniques for material processing on earth and in space.

  10. An approximate formula for recalescence in binary eutectic alloys

    SciTech Connect

    Ohsaka, K.; Trinh, E.H. . Jet Propulsion Lab.)

    1993-09-01

    Supercooling of a liquid prior to the nucleation of a solid and the subsequent rapid growth are necessary conditions for producing novel microstructures including metastable phases which are not formed by conventional solidification processes. Since containerless techniques, such as levitation and free fall of a sample, are capable of achieving a significant supercooling level of liquids, they are under consideration as possible techniques for material processing on earth and in space. It is known, however, that the supercooling level rapidly diminishes as solidification proceeds because the heat released on the phase transformation is mainly absorbed by the supercooled liquid. This self-heating process termed recalescence is a result of insufficient heat dissipation by radiation or convection in container less solidification. As a consequence, the rapid growth of the solid comes to a halt and the rest of the solidification is controlled by the heat dissipation rate to the surroundings. The extent of the solid formed during recalescence is proportional to the initial supercooling level. It is of interest to estimate the fraction of the solid from the thermodynamic information of the material.

  11. Approximation methods in gravitational-radiation theory

    NASA Technical Reports Server (NTRS)

    Will, C. M.

    1986-01-01

    The observation of gravitational-radiation damping in the binary pulsar PSR 1913 + 16 and the ongoing experimental search for gravitational waves of extraterrestrial origin have made the theory of gravitational radiation an active branch of classical general relativity. In calculations of gravitational radiation, approximation methods play a crucial role. Recent developments are summarized in two areas in which approximations are important: (a) the quadrupole approxiamtion, which determines the energy flux and the radiation reaction forces in weak-field, slow-motion, source-within-the-near-zone systems such as the binary pulsar; and (b) the normal modes of oscillation of black holes, where the Wentzel-Kramers-Brillouin approximation gives accurate estimates of the complex frequencies of the modes.

  12. DPI: Symplectic mapping for binary star systems for the Mercury software package

    NASA Astrophysics Data System (ADS)

    Turrini, D.

    2015-04-01

    DPI is a FORTRAN77 library that supplies the symplectic mapping method for binary star systems for the Mercury N-Body software package (ascl:1201.008). The binary symplectic mapping is implemented as a hybrid symplectic method that allows close encounters and collisions between massive bodies and is therefore suitable for planetary accretion simulations.

  13. A Galactic Binary Detection Pipeline

    NASA Technical Reports Server (NTRS)

    Littenberg, Tyson B.

    2011-01-01

    The Galaxy is suspected to contain hundreds of millions of binary white dwarf systems, a large fraction of which will have sufficiently small orbital period to emit gravitational radiation in band for space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA). LISA's main science goal is the detection of cosmological events (supermassive black hole mergers, etc.) however the gravitational signal from the galaxy will be the dominant contribution to the data - including instrumental noise over approximately two decades in frequency. The catalogue of detectable binary systems will serve as an unparalleled means of studying the Galaxy. Furthermore, to maximize the scientific return from the mission, the data must be "cleansed" of the galactic foreground. We will present an algorithm that can accurately resolve and subtract 2:: 10000 of these sources from simulated data supplied by the Mock LISA Data Challenge Task Force. Using the time evolution of the gravitational wave frequency, we will reconstruct the position of the recovered binaries and show how LISA will sample the entire compact binary population in the Galaxy.

  14. Interpolation and Approximation Theory.

    ERIC Educational Resources Information Center

    Kaijser, Sten

    1991-01-01

    Introduced are the basic ideas of interpolation and approximation theory through a combination of theory and exercises written for extramural education at the university level. Topics treated are spline methods, Lagrange interpolation, trigonometric approximation, Fourier series, and polynomial approximation. (MDH)

  15. 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.

  16. Evolution of a Ring around the Pluto-Charon Binary

    NASA Astrophysics Data System (ADS)

    Bromley, Benjamin C.; Kenyon, Scott J.

    2015-08-01

    We consider the formation of satellites around the Pluto-Charon binary. An early collision between the two partners likely produced the binary and a narrow ring of debris, out of which arose the moons Styx, Nix, Kerberos, and Hydra. How the satellites emerged from the compact ring is uncertain. Here we show that a particle ring spreads from physical collisions and collective gravitational scattering, similar to migration. Around a binary, these processes take place in the reference frames of “most circular” orbits, akin to circular ones in a Keplerian potential. Ring particles damp to these orbits and avoid destructive collisions. Damping and diffusion also help particles survive dynamical instabilities driven by resonances with the binary. In some situations, particles become trapped near resonances that sweep outward with the tidal evolution of the Pluto-Charon binary. With simple models and numerical experiments, we show how the Pluto-Charon impact ring may have expanded into a broad disk, out of which grew the circumbinary moons. In some scenarios, the ring can spread well beyond the orbit of Hydra, the most distant moon, to form a handful of smaller satellites. If these small moons exist, New Horizons will find them.

  17. EVOLUTION OF A RING AROUND THE PLUTO–CHARON BINARY

    SciTech Connect

    Bromley, Benjamin C.; Kenyon, Scott J. E-mail: skenyon@cfa.harvard.edu

    2015-08-10

    We consider the formation of satellites around the Pluto–Charon binary. An early collision between the two partners likely produced the binary and a narrow ring of debris, out of which arose the moons Styx, Nix, Kerberos, and Hydra. How the satellites emerged from the compact ring is uncertain. Here we show that a particle ring spreads from physical collisions and collective gravitational scattering, similar to migration. Around a binary, these processes take place in the reference frames of “most circular” orbits, akin to circular ones in a Keplerian potential. Ring particles damp to these orbits and avoid destructive collisions. Damping and diffusion also help particles survive dynamical instabilities driven by resonances with the binary. In some situations, particles become trapped near resonances that sweep outward with the tidal evolution of the Pluto–Charon binary. With simple models and numerical experiments, we show how the Pluto–Charon impact ring may have expanded into a broad disk, out of which grew the circumbinary moons. In some scenarios, the ring can spread well beyond the orbit of Hydra, the most distant moon, to form a handful of smaller satellites. If these small moons exist, New Horizons will find them.

  18. Birth of Massive Black Hole Binaries

    SciTech Connect

    Colpi, M.; Dotti, M.; Mayer, L.; Kazantzidis, S.; /KIPAC, Menlo Park

    2007-11-19

    If massive black holes (BHs) are ubiquitous in galaxies and galaxies experience multiple mergers during their cosmic assembly, then BH binaries should be common albeit temporary features of most galactic bulges. Observationally, the paucity of active BH pairs points toward binary lifetimes far shorter than the Hubble time, indicating rapid inspiral of the BHs down to the domain where gravitational waves lead to their coalescence. Here, we review a series of studies on the dynamics of massive BHs in gas-rich galaxy mergers that underscore the vital role played by a cool, gaseous component in promoting the rapid formation of the BH binary. The BH binary is found to reside at the center of a massive self-gravitating nuclear disc resulting from the collision of the two gaseous discs present in the mother galaxies. Hardening by gravitational torques against gas in this grand disc is found to continue down to sub-parsec scales. The eccentricity decreases with time to zero and when the binary is circular, accretion sets in around the two BHs. When this occurs, each BH is endowed with it own small-size ({approx}< 0.01 pc) accretion disc comprising a few percent of the BH mass. Double AGN activity is expected to occur on an estimated timescale of {approx}< 1 Myr. The double nuclear point-like sources that may appear have typical separation of {approx}< 10 pc, and are likely to be embedded in the still ongoing starburst. We note that a potential threat of binary stalling, in a gaseous environment, may come from radiation and/or mechanical energy injections by the BHs. Only short-lived or sub-Eddington accretion episodes can guarantee the persistence of a dense cool gas structure around the binary necessary for continuing BH inspiral.

  19. Centrality dependence of particle production in p - Pb collisions at s NN = 5.02 TeV

    DOE PAGES

    Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

    2015-06-08

    We report measurements of the primary charged-particle pseudorapidity density and transverse momentum distributions in p-Pb collisions at √sNN=5.02TeV and investigate their correlation with experimental observables sensitive to the centrality of the collision. Centrality classes are defined by using different event-activity estimators, i.e., charged-particle multiplicities measured in three different pseudorapidity regions as well as the energy measured at beam rapidity (zero degree). The procedures to determine the centrality, quantified by the number of participants (Npart) or the number of nucleon-nucleon binary collisions (Ncoll) are described. We show that, in contrast to Pb-Pb collisions, in p-Pb collisions large multiplicity fluctuations together withmore » the small range of participants available generate a dynamical bias in centrality classes based on particle multiplicity. We propose to use the zero-degree energy, which we expect not to introduce a dynamical bias, as an alternative event-centrality estimator. Based on zero-degree energy-centrality classes, the Npart dependence of particle production is studied. Under the assumption that the multiplicity measured in the Pb-going rapidity region scales with the number of Pb participants, an approximate independence of the multiplicity per participating nucleon measured at mid-rapidity of the number of participating nucleons is observed. Furthermore, at high-pT the p-Pb spectra are found to be consistent with the pp spectra scaled by Ncoll for all centrality classes. Our results represent valuable input for the study of the event-activity dependence of hard probes in p-Pb collisions and, hence, help to establish baselines for the interpretation of the Pb-Pb data.« less

  20. Centrality dependence of particle production in p -Pb collisions at √{sNN}=5.02 TeV

    NASA Astrophysics Data System (ADS)

    Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agostinelli, A.; Agrawal, N.; Ahammed, Z.; Ahmed, I.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, S.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Catanescu, V.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deloff, A.; Dénes, E.; D'Erasmo, G.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Dutta Majumdar, A. K.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdal, H. A.; Eschweiler, D.; Espagnon, B.; Esposito, M.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghidini, B.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J.; Grosse-Oetringhaus, J. F.; Grosso, R.; Grossiord, J.-Y.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Innocenti, G. M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Jachołkowski, A.; Jacobs, P. M.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kadyshevskiy, V.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Ketzer, B.; Khan, K. H.; Khan, M. M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kovalenko, V.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kucheriaev, Y.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, J.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Legrand, I.; Lehnert, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Lohner, D.; Loizides, C.; Lokesh, K.; Lopez, X.; López Torres, E.; Lowe, A.; Lu, X.-G.; Luettig, P.; Lunardon, M.; Luparello, G.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martashvili, I.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mlynarz, J.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira de Godoy, D. A.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Müller, H.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Nilsen, B. S.; Noferini, F.; Nomokonov, P.; Nooren, G.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Onderwaater, J.; Oppedisano, C.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Patalakha, D. I.; Paticchio, V.; Paul, B.; Pawlak, T.; Peitzmann, T.; Pereira da Costa, H.; Pereira de Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petris, M.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Pohjoisaho, E. H. O.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Rauf, A. W.; Razazi, V.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reicher, M.; Reidt, F.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohni, S.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seeder, K. S.; Segato, G.; Seger, J. E.; Sekiguchi, Y.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabetai, A.; Shabratova, G.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Skjerdal, K.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tanaka, N.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yano, S.; Yasnopolskiy, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

    2015-06-01

    We report measurements of the primary charged-particle pseudorapidity density and transverse momentum distributions in p -Pb collisions at √{sNN}=5.02 TeV and investigate their correlation with experimental observables sensitive to the centrality of the collision. Centrality classes are defined by using different event-activity estimators, i.e., charged-particle multiplicities measured in three different pseudorapidity regions as well as the energy measured at beam rapidity (zero degree). The procedures to determine the centrality, quantified by the number of participants (Npart) or the number of nucleon-nucleon binary collisions (Ncoll) are described. We show that, in contrast to Pb-Pb collisions, in p -Pb collisions large multiplicity fluctuations together with the small range of participants available generate a dynamical bias in centrality classes based on particle multiplicity. We propose to use the zero-degree energy, which we expect not to introduce a dynamical bias, as an alternative event-centrality estimator. Based on zero-degree energy-centrality classes, the Npart dependence of particle production is studied. Under the assumption that the multiplicity measured in the Pb-going rapidity region scales with the number of Pb participants, an approximate independence of the multiplicity per participating nucleon measured at mid-rapidity of the number of participating nucleons is observed. Furthermore, at high-pT the p -Pb spectra are found to be consistent with the p p spectra scaled by Ncoll for all centrality classes. Our results represent valuable input for the study of the event-activity dependence of hard probes in p -Pb collisions and, hence, help to establish baselines for the interpretation of the Pb-Pb data.

  1. Capacitor-Chain Successive-Approximation ADC

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas

    2003-01-01

    A proposed successive-approximation analog-to-digital converter (ADC) would contain a capacitively terminated chain of identical capacitor cells. Like a conventional successive-approximation ADC containing a bank of binary-scaled capacitors, the proposed ADC would store an input voltage on a sample-and-hold capacitor and would digitize the stored input voltage by finding the closest match between this voltage and a capacitively generated sum of binary fractions of a reference voltage (Vref). However, the proposed capacitor-chain ADC would offer two major advantages over a conventional binary-scaled-capacitor ADC: (1) In a conventional ADC that digitizes to n bits, the largest capacitor (representing the most significant bit) must have 2(exp n-1) times as much capacitance, and hence, approximately 2(exp n-1) times as much area as does the smallest capacitor (representing the least significant bit), so that the total capacitor area must be 2(exp n) times that of the smallest capacitor. In the proposed capacitor-chain ADC, there would be three capacitors per cell, each approximately equal to the smallest capacitor in the conventional ADC, and there would be one cell per bit. Therefore, the total capacitor area would be only about 3(exp n) times that of the smallest capacitor. The net result would be that the proposed ADC could be considerably smaller than the conventional ADC. (2) Because of edge effects, parasitic capacitances, and manufacturing tolerances, it is difficult to make capacitor banks in which the values of capacitance are scaled by powers of 2 to the required precision. In contrast, because all the capacitors in the proposed ADC would be identical, the problem of precise binary scaling would not arise.

  2. Collision orbits and chaos in the free-fall three-body problem.

    NASA Astrophysics Data System (ADS)

    Tanikawa, K.; Umehara, H.

    In this short report, the authors want to stress the chaotic nature of the final motions of the problem with reference to the distribution of binary collision curves and triple collision points. The calculation extends to the escapes at the first three collapses of the triple system. The Aarseth code to obtain the final motions is used.

  3. 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.

  4. 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.

  5. Ionization Cross Sections and Dissociation Channels of DNA Bases by Electron Collisions

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.; Dateo, Christopher E.; Fletcher, Graham D.

    2004-01-01

    Free secondary electrons are the most abundant secondary species in ionizing radiation. Their role in DNA damage, both direct and indirect, is an active area of research. While indirect damage by free radicals, particularly by the hydroxyl radical generated by electron collision with water. is relatively well studied, damage by direct electron collision with DNA is less well understood. Only recently Boudaiffa et al. demonstrated that electrons at energies well below ionization thresholds can induce substantial yields of single- and double-strand breaks in DNA by a resonant, dissociative attachment process. This study attracted renewed interest in electron collisions with DNA, especially in the low energy region. At higher energies ionization becomes important. While Monte Carlo track simulations of radiation damage always include ionization, the probability of dissociative ionization, i.e., simultaneous ionization and dissociation, is ignored. Just like dissociative attachment, dissociative ionization may be an important contributor to double-strand breaks since the radicals and ions produced by dissociative ionization, located in the vicinity of the DNA coil, can readily interact with other parts of the DNA. Using the improved binary-encounter dipole (iBED) formulation, we calculated the ionization cross sections of the four DNA bases, adenine, cytosine, guanine, and thymine, by electrons at energies from threshold to 1 KeV. The present calculation gives cross sections approximately 20% lower than the results by Bemhardt and Paretzke using the Deutsch-Mark and Binary-Encounter-Bethe (BEB) formalisms. The difference is most likely due to the lack of a shielding term in the dipole potential used in the Deutsch-Mark and BEB formalisms. The dissociation channels of ionization for the bases are currently being studied.

  6. Approximate learning algorithm in Boltzmann machines.

    PubMed

    Yasuda, Muneki; Tanaka, Kazuyuki

    2009-11-01

    Boltzmann machines can be regarded as Markov random fields. For binary cases, they are equivalent to the Ising spin model in statistical mechanics. Learning systems in Boltzmann machines are one of the NP-hard problems. Thus, in general we have to use approximate methods to construct practical learning algorithms in this context. In this letter, we propose new and practical learning algorithms for Boltzmann machines by using the belief propagation algorithm and the linear response approximation, which are often referred as advanced mean field methods. Finally, we show the validity of our algorithm using numerical experiments.

  7. 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.

  8. Suppression of hadrons with large transverse momentum in central Au+Au collisions at root square[s(NN)] = 130 GeV.

    PubMed

    Adcox, K; Adler, S S; Ajitanand, N N; Akiba, Y; Alexander, J; Aphecetche, L; Arai, Y; Aronson, S H; Averbeck, R; Awes, T C; Barish, K N; Barnes, P D; Barrette, J; Bassalleck, B; Bathe, S; Baublis, V; Bazilevsky, A; Belikov, S; Bellaiche, F G; Belyaev, S T; Bennett, M J; Berdnikov, Y; Botelho, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J; Butsyk, S; Carey, T A; Chand, P; Chang, J; Chang, W C; Chavez, L L; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choudhury, R K; Christ, T; Chujo, T; Chung, M S; Chung, P; Cianciolo, V; Cole, B A; D'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dinesh, B V; Drees, A; Durum, A; Dutta, D; Ebisu, K; Efremenko, Y V; El Chenawi, K; En'yo, H; Esumi, S; Ewell, L; Ferdousi, T; Fields, D E; Fokin, S L; Fraenkel, Z; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Godoi, A L; Goto, Y; Greene, S V; Grosse Perdekamp, M; Gupta, S K; Guryn, W; Gustafsson, H-A; Haggerty, J S; Hamagaki, H; Hansen, A G; Hara, H; Hartouni, E P; Hayano, R; Hayashi, N; He, X; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Ho, D S; Homma, K; Hong, B; Hoover, A; Ichihara, T; Imai, K; Ippolitov, M S; Ishihara, M; Jacak, B V; Jang, W Y; Jia, J; Johnson, B M; Johnson, S C; Joo, K S; Kametani, S; Kang, J H; Kann, M; Kapoor, S S; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, H J; Kim, S Y; Kim, Y G; Kinnison, W W; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Klinksiek, S; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kotchetkov, D; Kozlov, A; Kroon, P J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lauret, J; Lebedev, A; Lee, D M; Leitch, M J; Li, X H; Li, Z; Lim, D J; Liu, M X; Liu, X; Liu, Z; Maguire, C F; Mahon, J; Makdisi, Y I; Manko, V I; Mao, Y; Mark, S K; Markacs, S; Martinez, G; Marx, M D; Masaike, A; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Merschmeyer, M; Messer, F; Messer, M; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagasaka, Y; Nagle, J L; Nakada, Y; Nandi, B K; Newby, J; Nikkinen, L; Nilsson, P; Nishimura, S; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Ono, M; Onuchin, V; Oskarsson, A; Osterman, L; Otterlund, I; Oyama, K; Paffrath, L; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Pate, S F; Peitzmann, T; Petridis, A N; Pinkenburg, C; Pisani, R P; Pitukhin, P; Plasil, F; Pollack, M; Pope, K; Purschke, M L; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Rosati, M; Rose, A A; Ryu, S S; Saito, N; Sakaguchi, A; Sakaguchi, T; Sako, H; Sakuma, T; Samsonov, V; Sangster, T C; Santo, R; Sato, H D; Sato, S; Sawada, S; Schlei, B R; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shiina, T; Shin, Y H; Sibiriak, I G; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sorensen, S; Stankus, P W; Starinsky, N; Steinberg, P; Stenlund, E; Ster, A; Stoll, S P; Sugioka, M; Sugitate, T; Sullivan, J P; Sumi, Y; Sun, Z; Suzuki, M; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Taniguchi, E; Tannenbaum, M J; Thomas, J; Thomas, J H; Thomas, T L; Tian, W; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tsvetkov, A A; Tuli, S K; Tydesjö, H; Tyurin, N; Ushiroda, T; van Hecke, H W; Velissaris, C; Velkovska, J; Velkovsky, M; Vinogradov, A A; Volkov, M A; Vorobyov, A; Vznuzdaev, E; Wang, H; Watanabe, Y; White, S N; Witzig, C; Wohn, F K; Woody, C L; Xie, W; Yagi, K; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, Z; Zhou, S

    2002-01-14

    Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 GeV/ccollisions at root square[s(NN)] = 130 GeV. At high p(T) the spectra from peripheral nuclear collisions are consistent with scaling the spectra from p+p collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled p+p expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies.

  9. X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Lewin, Walter H. G.; van Paradijs, Jan; van den Heuvel, Edward Peter Jacobus

    1997-01-01

    Preface; 1. The properties of X-ray binaries, N. E. White, F. Nagase and A. N. Parmar; 2. Optical and ultraviolet observations of X-ray binaries J. van Paradijs and J. E. McClintock; 3. Black-hole binaries Y. Tanaka and W. H. G. Lewin; 4. X-ray bursts Walter H. G. Lewin, Jan Van Paradijs and Ronald E. Taam; 5. Millisecond pulsars D. Bhattacharya; 6. Rapid aperiodic variability in binaries M. van der Klis; 7. Radio properties of X-ray binaries R. M. Hjellming and X. Han; 8. Cataclysmic variable stars France Anne-Dominic Córdova; 9. Normal galaxies and their X-ray binary populations G. Fabbiano; 10. Accretion in close binaries Andrew King; 11. Formation and evolution of neutron stars and black holes in binaries F. Verbunt and E. P. J. van den Heuvel; 12. The magnetic fields of neutron stars and their evolution D. Bhattacharya and G. Srinivasan; 13. Cosmic gamma-ray bursts K. Hurley; 14. A catalogue of X-ray binaries Jan van Paradijs; 15. A compilation of cataclysmic binaries with known or suspected orbital periods Hans Ritter and Ulrich Kolb; References; Index.

  10. Approximate flavor symmetries

    SciTech Connect

    Rasin, A.

    1994-04-01

    We discuss the idea of approximate flavor symmetries. Relations between approximate flavor symmetries and natural flavor conservation and democracy models is explored. Implications for neutrino physics are also discussed.

  11. Life and Death of Binaries Near the Galactic Center

    NASA Astrophysics Data System (ADS)

    Hills, J. G.

    2002-09-01

    On any astronomical timescale, binaries near the Galactic Center are strongly affected by interactions with their environment. We shall consider these processes. The high density of stars and possibly WIMPS (weakly interacting, massive particles) cause interactions that change the semimajor axes and eccentricities of the binaries. Interactions with more massive stars may, through exchange collisions, lead to a progressive increase in the masses of the binary components. Some binaries are destroyed through the coalescence of their components due to the high eccentricity that they attain. Others will be destroyed by encounters with energetic intruders that are capable of dissociating the binaries. The binaries that most easily surivive in this hostile environment have small semimajor axes and only white dwarf, neutron star, or black hole components,as such objects have little chance of coalescence under normal circumstances. These compact objects are also massive enough compared to the mass of the average star near the Galactic center that there is much less danger of their binary being disrupted in an encounter. Even binaries with compact companions have short lifetimes if their semimajor axes are less than 2 A.U. because they are forced into coalescence by the emission of gravitational radiation. The tidal field of the central black hole will distrupt binaries that pass close enough to it. If WIMPS make up any sizeable fraction of the mass density at the Galactic Center, they will cause a steady contraction of the semimajor axes of the binaries that may be measurable if one binary component is a pulsar.

  12. Energy and angular distributions of detached electrons in a solvable model of ion-atom collisions

    SciTech Connect

    Macek, J.H.; Ovchinnikov, S.Y. |; Solovev, E.A.

    1999-08-01

    Electron energy and angular distributions are computed for a model of atom{endash}negative-ion collisions. In this model, electron-atom interactions are represented by zero-range potentials in an approximation where two identical atoms move along straight-line classical trajectories in head-on collisions. Analytic expressions for the ionization amplitudes are interpreted in terms of Sturmian eigenvalues and eigenfunctions. At high velocity, the computed distributions exhibit direct excitation and continuum capture cusps in addition to the binary encounter ridge. At low velocities, a single feature corresponding to an electron distribution centered midway between the target and projectile emerges. For initial conditions corresponding to gerade symmetry a single broad peak appears, while for ungerade symmetry there is a node at the midpoint so that the peak splits into two parts. It is confirmed that the advanced adiabatic approximation gives an accurate description of the ungerade distribution at low and intermediate velocities. {copyright} {ital 1999} {ital The American Physical Society}

  13. Energy and angular distributions of detached electrons in a solvable model of ion-atom collisions

    SciTech Connect

    Macek, J.H.; Ovchinnikov, S.Y. Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 ); Solovev, E.A. )

    1999-08-01

    Electron energy and angular distributions are computed for a model of atom[endash]negative-ion collisions. In this model, electron-atom interactions are represented by zero-range potentials in an approximation where two identical atoms move along straight-line classical trajectories in head-on collisions. Analytic expressions for the ionization amplitudes are interpreted in terms of Sturmian eigenvalues and eigenfunctions. At high velocity, the computed distributions exhibit direct excitation and continuum capture cusps in addition to the binary encounter ridge. At low velocities, a single feature corresponding to an electron distribution centered midway between the target and projectile emerges. For initial conditions corresponding to gerade symmetry a single broad peak appears, while for ungerade symmetry there is a node at the midpoint so that the peak splits into two parts. It is confirmed that the advanced adiabatic approximation gives an accurate description of the ungerade distribution at low and intermediate velocities. [copyright] [ital 1999] [ital The American Physical Society

  14. Irradiation-induced composition patterns in binary solid solutions

    SciTech Connect

    Dubey, Santosh; El-Azab, Anter

    2013-09-28

    A theoretical/computational model for the irradiation-driven compositional instabilities in binary solid solutions has been developed. The model is suitable for investigating the behavior of structural alloys and metallic nuclear fuels in a reactor environment as well as the response of alloy thin films to ion beam irradiation. The model is based on a set of reaction-diffusion equations for the dynamics of vacancies, interstitials, and lattice atoms under irradiation. The dynamics of these species includes the stochastic generation of defects by collision cascades as well as the defect reactions and diffusion. The atomic fluxes in this model are derived based on the transitions of lattice defects. The set of reaction-diffusion equations are stiff, hence a stiffly stable method, also known as the Gear method, has been used to numerically approximate the equations. For the Cu-Au alloy in the solid solution regime, the model results demonstrate the formation of compositional patterns under high-temperature particle irradiation, with Fourier space properties (Fourier spectrum, average wavelength, and wavevector) depending on the cascade damage characteristics, average composition, and irradiation temperature.

  15. Approximation of Laws

    NASA Astrophysics Data System (ADS)

    Niiniluoto, Ilkka

    2014-03-01

    Approximation of laws is an important theme in the philosophy of science. If we can make sense of the idea that two scientific laws are "close" to each other, then we can also analyze such methodological notions as approximate explanation of laws, approximate reduction of theories, approximate empirical success of theories, and approximate truth of laws. Proposals for measuring the distance between quantitative scientific laws were given in Niiniluoto (1982, 1987). In this paper, these definitions are reconsidered as a response to the interesting critical remarks by Liu (1999).

  16. Massive Stars in Interactive Binaries

    NASA Astrophysics Data System (ADS)

    St.-Louis, Nicole; Moffat, Anthony F. J.

    Massive stars start their lives above a mass of ~8 time solar, finally exploding after a few million years as core-collapse or pair-production supernovae. Above ~15 solar masses, they also spend most of their lives driving especially strong, hot winds due to their extreme luminosities. All of these aspects dominate the ecology of the Universe, from element enrichment to stirring up and ionizing the interstellar medium. But when they occur in close pairs or groups separated by less than a parsec, the interaction of massive stars can lead to various exotic phenomena which would not be seen if there were no binaries. These depend on the actual separation, and going from wie to close including colliding winds (with non-thermal radio emission and Wolf-Rayet dust spirals), cluster dynamics, X-ray binaries, Roche-lobe overflow (with inverse mass-ratios and rapid spin up), collisions, merging, rejuventation and massive blue stragglers, black-hole formation, runaways and gamma-ray bursts. Also, one wonders whether the fact that a massive star is in a binary affects its parameters compared to its isolated equivalent. These proceedings deal with all of these phenomena, plus binary statistics and determination of general physical properties of massive stars, that would not be possible with their single cousins. The 77 articles published in these proceedings, all based on oral talks, vary from broad revies to the lates developments in the field. About a third of the time was spent in open discussion of all participants, both for ~5 minutes after each talk and 8 half-hour long general dialogues, all audio-recorded, transcribed and only moderately edited to yield a real flavour of the meeting. The candid information in these discussions is sometimes more revealing than the article(s) that preceded them and also provide entertaining reading. The book is suitable for researchers and graduate students interested in stellar astrophysics and in various physical processes involved when

  17. THE ROLE OF KOZAI CYCLES IN NEAR-EARTH BINARY ASTEROIDS

    SciTech Connect

    Fang, Julia; Margot, Jean-Luc

    2012-03-15

    We investigate the Kozai mechanism in the context of near-Earth binaries and the Sun. The Kozai effect can lead to changes in eccentricity and inclination of the binary orbit, but it can be weakened or completely suppressed by other sources of pericenter precession, such as the oblateness of the primary body. Through numerical integrations including primary oblateness and three bodies (the two binary components and the Sun), we show that Kozai cycles cannot occur for the closely separated near-Earth binaries in our sample. We demonstrate that this is due to pericenter precession around the oblate primary, even for very small oblateness values. Since the majority of observed near-Earth binaries are not well separated, we predict that Kozai cycles do not play an important role in the orbital evolution of most near-Earth binaries. For a hypothetical wide binary modeled after 1998 ST27, the separation is large at 16 primary radii and so the orbital effects of primary oblateness are lessened. For this wide binary, we illustrate the possible excursions in eccentricity and inclination due to Kozai cycles as well as depict stable orientations for the binary's orbital plane. Unstable orientations lead to collisions between binary components, and we suggest that the Kozai effect acting in wide binaries may be a route to the formation of near-Earth contact binaries.

  18. The extreme Kuiper Belt binary 2001 QW322.

    PubMed

    Petit, J-M; Kavelaars, J J; Gladman, B J; Margot, J L; Nicholson, P D; Jones, R L; Parker, J Wm; Ashby, M L N; Bagatin, A Campo; Benavidez, P; Coffey, J; Rousselot, P; Mousis, O; Taylor, P A

    2008-10-17

    The study of binary Kuiper Belt objects helps to probe the dynamic conditions present during planet formation in the solar system. We report on the mutual-orbit determination of 2001 QW322, a Kuiper Belt binary with a very large separation whose properties challenge binary-formation and -evolution theories. Six years of tracking indicate that the binary's mutual-orbit period is approximately 25 to 30 years, that the orbit pole is retrograde and inclined 50 degrees to 62 degrees from the ecliptic plane, and, most surprisingly, that the mutual orbital eccentricity is <0.4. The semimajor axis of 105,000 to 135,000 kilometers is 10 times that of other near-equal-mass binaries. Because this weakly bound binary is prone to orbital disruption by interlopers, its lifetime in its present state is probably less than 1 billion years.

  19. The formation of eccentric compact binary inspirals and the role of gravitational wave emission in binary-single stellar encounters

    SciTech Connect

    Samsing, Johan; MacLeod, Morgan; Ramirez-Ruiz, Enrico

    2014-03-20

    The inspiral and merger of eccentric binaries leads to gravitational waveforms distinct from those generated by circularly merging binaries. Dynamical environments can assemble binaries with high eccentricity and peak frequencies within the LIGO band. In this paper, we study binary-single stellar scatterings occurring in dense stellar systems as a source of eccentrically inspiraling binaries. Many interactions between compact binaries and single objects are characterized by chaotic resonances in which the binary-single system undergoes many exchanges before reaching a final state. During these chaotic resonances, a pair of objects has a non-negligible probability of experiencing a very close passage. Significant orbital energy and angular momentum are carried away from the system by gravitational wave (GW) radiation in these close passages, and in some cases this implies an inspiral time shorter than the orbital period of the bound third body. We derive the cross section for such dynamical inspiral outcomes through analytical arguments and through numerical scattering experiments including GW losses. We show that the cross section for dynamical inspirals grows with increasing target binary semi-major axis a and that for equal-mass binaries it scales as a {sup 2/7}. Thus, we expect wide target binaries to predominantly contribute to the production of these relativistic outcomes. We estimate that eccentric inspirals account for approximately 1% of dynamically assembled non-eccentric merging binaries. While these events are rare, we show that binary-single scatterings are a more effective formation channel than single-single captures for the production of eccentrically inspiraling binaries, even given modest binary fractions.

  20. Cool Star Binaries with ALEXIS

    NASA Technical Reports Server (NTRS)

    Stern, Robert A.

    1998-01-01

    We proposed to search for high-temperature, flare-produced Fe XXIII line emission from active cool star binary systems using the ALEXIS all-sky survey. Previous X-ray transient searches with ARIEL V and HEAO-1, and subsequent shorter duration monitoring with the GINGA and EXOSAT satellites demonstrated that active binaries can produce large (EM approximately equals 10(exp 55-56/cu cm) X-ray flares lasting several hours or longer. Hot plasma from these flares at temperatures of 10(exp 7)K or more should produce Fe XXIII line emission at lambda = 132.8 A, very near the peak response of ALEXIS telescopes 1A and 2A. Our primary goals were to estimate flare frequency for the largest flares in the active binary systems, and, if the data permitted, to derive a distribution of flare energy vs. frequency for the sample as a whole. After a long delay due to the initial problems with the ALEXIS attitude control, the heroic efforts on the part of the ALEXIS satellite team enabled us to carry out this survey. However, the combination of the higher than expected and variable background in the ALEXIS detectors, and the lower throughput of the ALEXIS telescopes resulted in no convincing detections of large flares from the active binary systems. In addition, vignetting-corrected effective exposure times from the ALEXIS aspect solution were not available prior to the end of this contract; therefore, we were unable to convert upper limits measured in ALEXIS counts to the equivalent L(sub EUV).

  1. Case A Binary Evolution

    SciTech Connect

    Nelson, C A; Eggleton, P P

    2001-03-28

    We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M{sub 10}, mass ratio q{sub 0}, and period P{sub 0}, designed to sample the phase-space of Case A binaries in the range -0.10 {le} log M{sub 10} {le} 1.7. Each binary is evolved using a standard code with the assumption that both total mass and orbital angular momentum are conserved. This code follows the evolution of both stars until the point where contact or reverse mass transfer occurs. The resulting binary tracks show a rich variety of behavior which we sort into several subclasses of Case A and Case B. We present the results of this classification, the final mass ratio and the fraction of time spent in Roche Lobe overflow for each binary system. The conservative assumption under which we created this library is expected to hold for a broad range of binaries, where both components have spectra in the range G0 to B1 and luminosity class III - V. We gather a list of relatively well-determined observed hot Algol-type binaries meeting this criterion, as well as a list of cooler Algol-type binaries where we expect significant dynamo-driven mass loss and angular momentum loss. We fit each observed binary to our library of tracks using a {chi}{sup 2}-minimizing procedure. We find that the hot Algols display overall acceptable {chi}{sup 2}, confirming the conservative assumption, while the cool Algols show much less acceptable {chi}{sup 2} suggesting the need for more free parameters, such as mass and angular momentum loss.

  2. FORMATION OF BLACK HOLE X-RAY BINARIES IN GLOBULAR CLUSTERS

    SciTech Connect

    Ivanova, N.; Heinke, C. O.; Woods, T. E.; Chaichenets, S.; Fregeau, J.; Lombardi, J. C.

    2010-07-10

    Inspired by the recent identification in extragalactic globular clusters of the first candidate black hole-white dwarf (BH-WD) X-ray binaries, where the compact accretors may be stellar-mass black holes (BHs), we explore how such binaries could be formed in a dynamical environment. We provide analyses of the formation rates via well-known formation channels like binary exchange and physical collisions and propose that the only possibility of forming BH-WD binaries is via coupling these usual formation channels with subsequent hardening and/or triple formation. In particular, we find that the most important mechanism for the creation of a BH-WD X-ray binary from an initially dynamically formed BH-WD binary is mass transfer induced in a triple system via the Kozai mechanism. Furthermore, we find that BH-WD binaries that evolve into X-ray sources can be formed by exchanges of a BH into a WD-WD binary or possibly by collisions of a BH and a giant star. If BHs undergo significant evaporation from the cluster or form a completely detached subcluster of BHs, then we cannot match the observationally inferred production rates even using the most optimistic estimates of formation rates. To explain the observations with stellar-mass BH-WD binaries, at least 1% of all formed BHs, or presumably 10% of the BHs present in the core now, must be involved in interactions with the rest of the core stellar population.

  3. PLANET FORMATION IN HIGHLY INCLINED BINARY SYSTEMS. I. PLANETESIMALS JUMP INWARD AND PILE UP

    SciTech Connect

    Xie Jiwei; Zhou Jilin; Payne, Matthew J.; Ge Jian; Thebault, Philippe

    2011-07-01

    Most detected planet-bearing binaries are in wide orbits, for which a high inclination, i{sub B} , between the binary orbital plane and the plane of the planetary disk around the primary is likely to be common. In this paper, we investigate the intermediate stages-from planetesimals to planetary embryos/cores-of planet formation in such highly inclined cases. Our focus is on the effects of gas drag on the planetesimals' orbital evolution, in particular on the evolution of the planetesimals' semimajor axis distribution and their mutual relative velocities. We first demonstrate that a non-evolving axisymmetric disk model is a good approximation for studying the effects of gas drag on a planetesimal in the highly inclined case (30 deg. < i{sub B} < 150 deg.). We then find that gas drag plays a crucial role, and the results can be generally divided into two categories, i.e., the Kozai-on regime and the Kozai-off regime, depending on the specific value of i{sub B} . For both regimes, a robust outcome over a wide range of parameters is that planetesimals migrate/jump inward and pile up, leading to a severely truncated and dense planetesimal disk around the primary. In this compact and dense disk, collision rates are high but relative velocities are low, providing conditions that are favorable for planetesimal growth and potentially allow for the subsequent formation of planets.

  4. 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.

  5. Approximate spatial reasoning

    NASA Technical Reports Server (NTRS)

    Dutta, Soumitra

    1988-01-01

    A model for approximate spatial reasoning using fuzzy logic to represent the uncertainty in the environment is presented. Algorithms are developed which can be used to reason about spatial information expressed in the form of approximate linguistic descriptions similar to the kind of spatial information processed by humans. Particular attention is given to static spatial reasoning.

  6. Azimuthal Anisotropy in U +U and Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; 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.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, H. Z.; Huang, B.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, W.; Li, Y.; Li, C.; Li, Z. M.; Li, X.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, L.; Ma, R.; Ma, Y. G.; Ma, G. L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; 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.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, Y.; Wang, H.; Wang, J. S.; Wang, Y.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, Y. F.; Xu, N.; Xu, Z.; Xu, Q. H.; Xu, H.; Yang, Y.; Yang, Y.; Yang, C.; Yang, S.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, J. B.; Zhang, J.; Zhang, Z.; Zhang, S.; Zhang, Y.; Zhang, J. L.; Zhao, F.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-11-01

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2 } and v2{4 }, for charged hadrons from U +U collisions at √{sNN }=193 GeV and Au +Au collisions at √{sNN}=200 GeV . Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2 } on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U +U collisions. We also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  7. Green Ampt approximations

    NASA Astrophysics Data System (ADS)

    Barry, D. A.; Parlange, J.-Y.; Li, L.; Jeng, D.-S.; Crapper, M.

    2005-10-01

    The solution to the Green and Ampt infiltration equation is expressible in terms of the Lambert W-1 function. Approximations for Green and Ampt infiltration are thus derivable from approximations for the W-1 function and vice versa. An infinite family of asymptotic expansions to W-1 is presented. Although these expansions do not converge near the branch point of the W function (corresponds to Green-Ampt infiltration with immediate ponding), a method is presented for approximating W-1 that is exact at the branch point and asymptotically, with interpolation between these limits. Some existing and several new simple and compact yet robust approximations applicable to Green-Ampt infiltration and flux are presented, the most accurate of which has a maximum relative error of 5 × 10 -5%. This error is orders of magnitude lower than any existing analytical approximations.

  8. Forward electron production in heavy ion-atom and ion-solid collisions

    SciTech Connect

    Sellin, I.A.

    1984-01-01

    A sharp cusp in the velocity spectrum of electrons, ejected in ion-atom and ion-solid collisions, is observed when the ejected electron velocity vector v/sub e/ matches that of the emergent ion vector v/sub p/ in both speed and direction. In ion-atom collisions, the electrons originate from capture to low-lying, projectile-centered continuum states (ECC) for fast bare or nearly bare projectiles, and from loss to those low-lying continuum states (ELC) when loosely bound projectile electrons are available. Most investigators now agree that ECC cusps are strongly skewed toward lower velocities, and exhibit full widths half maxima roughly proportional to v/sub p/ (neglecting target-shell effects, which are sometimes strong). A close examination of recent ELC data shows that ELC cusps are instead nearly symmetric, with widths nearly independent on v/sub p/ in the velocity range 6 to 18 a.u., a result only recently predicted by theory. Convoy electron cusps produced in heavy ion-solid collisions at MeV/u energies exhibit approximately velocity-independent widths very similar to ELC cusp widths. While the shape of the convoy peaks is approximately independent of projectile Z, velocity, and of target material, it is found that the yields in polycrystalline targets exhibit a strong dependence on projectile Z and velocity. While attempts have been made to link convoy electron production to binary ECC or ELC processes, sometimes at the last layer, or alternatively to a solid-state wake-riding model, our measured dependences of cusp shape and yield on projectile charge state and energy are inconsistent with the predictions of available theories. 10 references, 8 figures, 1 table.

  9. Tidal torques on infrequently colliding particle disks in binary systems and the truncation of the asteroid belt

    NASA Technical Reports Server (NTRS)

    Franklin, F. A.; Lecar, M.; Lin, D. N. C.; Papaloizou, J.

    1980-01-01

    Conditions leading to the truncation, at the 2:1 resonance, of a disk of infrequently colliding particles surrounding the primary of a binary system are studied numerically and analytically. Attention is given to the case in which the mass ratio, q, is sufficiently small (less than about 0.1) and the radius of the disk centered on the primary allowably larger, so that first-order orbit-orbit resonances between ring material and the secondary can lie within it. Collisions are found to be less frequent than q to the -2/3 power orbital periods (the period of the forced eccentricity at the 2:1 resonance), and truncation occurs and Kirkwood gaps are produced only if the particle eccentricity is less than some critical value, estimated to be of order q to the 5/9 power, or approximately 0.02 for the sun-Jupiter case having q equal to 10 to the -3rd power.

  10. Toward a Physical Characterization of Raindrop Collision Outcome Regimes

    NASA Technical Reports Server (NTRS)

    Testik, F. Y.; Barros, Ana P.; Bilven, Francis L.

    2011-01-01

    A comprehensive raindrop collision outcome regime diagram that delineates the physical conditions associated with the outcome regimes (i.e., bounce, coalescence, and different breakup types) of binary raindrop collisions is proposed. The proposed diagram builds on a theoretical regime diagram defined in the phase space of collision Weber numbers We and the drop diameter ratio p by including critical angle of impact considerations. In this study, the theoretical regime diagram is first evaluated against a comprehensive dataset for drop collision experiments representative of raindrop collisions in nature. Subsequently, the theoretical regime diagram is modified to explicitly describe the dominant regimes of raindrop interactions in (We, p) by delineating the physical conditions necessary for the occurrence of distinct types of collision-induced breakup (neck/filament, sheet, disk, and crown breakups) based on critical angle of impact consideration. Crown breakup is a subtype of disk breakup for lower collision kinetic energy that presents distinctive morphology. Finally, the experimental results are analyzed in the context of the comprehensive collision regime diagram, and conditional probabilities that can be used in the parameterization of breakup kernels in stochastic models of raindrop dynamics are provided.

  11. Taming the binaries

    NASA Astrophysics Data System (ADS)

    Pourbaix, D.

    2008-07-01

    Astrometric binaries are both a gold mine and a nightmare. They are a gold mine because they are sometimes the unique source of orbital inclination for spectroscopic binaries, thus making it possible for astrophysicists to get some clues about the mass of the often invisible secondary. However, this is an ideal situation in the sense that one benefits from the additional knowledge that it is a binary for which some orbital parameters are somehow secured (e.g. the orbital period). On the other hand, binaries are a nightmare, especially when their binary nature is not established yet. Indeed, in such cases, depending on the time interval covered by the observations compared to the orbital period, either the parallax or the proper motion can be severely biased if the successive positions of the binary are modelled assuming it is a single star. With large survey campaigns sometimes monitoring some stars for the first time ever, it is therefore crucial to design robust reduction pipelines in which such troublesome objects are quickly identified and either removed or processed accordingly. Finally, even if an object is known not to be a single star, the binary model might turn out not to be the most appropriate for describing the observations. These different situations will be covered.

  12. 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.

  13. 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.

  14. Intrinsic Nilpotent Approximation.

    DTIC Science & Technology

    1985-06-01

    RD-A1II58 265 INTRINSIC NILPOTENT APPROXIMATION(U) MASSACHUSETTS INST 1/2 OF TECH CAMBRIDGE LAB FOR INFORMATION AND, DECISION UMCLRSSI SYSTEMS C...TYPE OF REPORT & PERIOD COVERED Intrinsic Nilpotent Approximation Technical Report 6. PERFORMING ORG. REPORT NUMBER LIDS-R-1482 7. AUTHOR(.) S...certain infinite-dimensional filtered Lie algebras L by (finite-dimensional) graded nilpotent Lie algebras or g . where x E M, (x,,Z) E T*M/O. It

  15. Anomalous diffraction approximation limits

    NASA Astrophysics Data System (ADS)

    Videen, Gorden; Chýlek, Petr

    It has been reported in a recent article [Liu, C., Jonas, P.R., Saunders, C.P.R., 1996. Accuracy of the anomalous diffraction approximation to light scattering by column-like ice crystals. Atmos. Res., 41, pp. 63-69] that the anomalous diffraction approximation (ADA) accuracy does not depend on particle refractive index, but instead is dependent on the particle size parameter. Since this is at odds with previous research, we thought these results warranted further discussion.

  16. Approximate spatial reasoning

    NASA Technical Reports Server (NTRS)

    Dutta, Soumitra

    1988-01-01

    Much of human reasoning is approximate in nature. Formal models of reasoning traditionally try to be precise and reject the fuzziness of concepts in natural use and replace them with non-fuzzy scientific explicata by a process of precisiation. As an alternate to this approach, it has been suggested that rather than regard human reasoning processes as themselves approximating to some more refined and exact logical process that can be carried out with mathematical precision, the essence and power of human reasoning is in its capability to grasp and use inexact concepts directly. This view is supported by the widespread fuzziness of simple everyday terms (e.g., near tall) and the complexity of ordinary tasks (e.g., cleaning a room). Spatial reasoning is an area where humans consistently reason approximately with demonstrably good results. Consider the case of crossing a traffic intersection. We have only an approximate idea of the locations and speeds of various obstacles (e.g., persons and vehicles), but we nevertheless manage to cross such traffic intersections without any harm. The details of our mental processes which enable us to carry out such intricate tasks in such apparently simple manner are not well understood. However, it is that we try to incorporate such approximate reasoning techniques in our computer systems. Approximate spatial reasoning is very important for intelligent mobile agents (e.g., robots), specially for those operating in uncertain or unknown or dynamic domains.

  17. Approximate kernel competitive learning.

    PubMed

    Wu, Jian-Sheng; Zheng, Wei-Shi; Lai, Jian-Huang

    2015-03-01

    Kernel competitive learning has been successfully used to achieve robust clustering. However, kernel competitive learning (KCL) is not scalable for large scale data processing, because (1) it has to calculate and store the full kernel matrix that is too large to be calculated and kept in the memory and (2) it cannot be computed in parallel. In this paper we develop a framework of approximate kernel competitive learning for processing large scale dataset. The proposed framework consists of two parts. First, it derives an approximate kernel competitive learning (AKCL), which learns kernel competitive learning in a subspace via sampling. We provide solid theoretical analysis on why the proposed approximation modelling would work for kernel competitive learning, and furthermore, we show that the computational complexity of AKCL is largely reduced. Second, we propose a pseudo-parallelled approximate kernel competitive learning (PAKCL) based on a set-based kernel competitive learning strategy, which overcomes the obstacle of using parallel programming in kernel competitive learning and significantly accelerates the approximate kernel competitive learning for large scale clustering. The empirical evaluation on publicly available datasets shows that the proposed AKCL and PAKCL can perform comparably as KCL, with a large reduction on computational cost. Also, the proposed methods achieve more effective clustering performance in terms of clustering precision against related approximate clustering approaches.

  18. The monoenergetic approximation in stellarator neoclassical calculations

    NASA Astrophysics Data System (ADS)

    Landreman, Matt

    2011-08-01

    In 'monoenergetic' stellarator neoclassical calculations, to expedite computation, ad hoc changes are made to the kinetic equation so speed enters only as a parameter. Here we examine the validity of this approach by considering the effective particle trajectories in a model magnetic field. We find monoenergetic codes systematically under-predict the true trapped particle fraction. The error in the trapped ion fraction can be of order unity for large but experimentally realizable values of the radial electric field, suggesting some results of these codes may be unreliable in this regime. This inaccuracy is independent of any errors introduced by approximation of the collision operator.

  19. Kepler Eclipsing Binary Stars. VIII. Identification of False Positive Eclipsing Binaries and Re-extraction of New Light Curves

    NASA Astrophysics Data System (ADS)

    Abdul-Masih, Michael; Prša, Andrej; Conroy, Kyle; Bloemen, Steven; Boyajian, Tabetha; Doyle, Laurance R.; Johnston, Cole; Kostov, Veselin; Latham, David W.; Matijevič, Gal; Shporer, Avi; Southworth, John

    2016-04-01

    The Kepler mission has provided unprecedented, nearly continuous photometric data of ∼200,000 objects in the ∼105 deg2 field of view (FOV) from the beginning of science operations in May of 2009 until the loss of the second reaction wheel in May of 2013. The Kepler Eclipsing Binary Catalog contains information including but not limited to ephemerides, stellar parameters, and analytical approximation fits for every known eclipsing binary system in the Kepler FOV. Using target pixel level data collected from Kepler in conjunction with the Kepler Eclipsing Binary Catalog, we identify false positives among eclipsing binaries, i.e., targets that are not eclipsing binaries themselves, but are instead contaminated by eclipsing binary sources nearby on the sky and show eclipsing binary signatures in their light curves. We present methods for identifying these false positives and for extracting new light curves for the true source of the observed binary signal. For each source, we extract three separate light curves for each quarter of available data by optimizing the signal-to-noise ratio, the relative percent eclipse depth, and the flux eclipse depth. We present 289 new eclipsing binaries in the Kepler FOV that were not targets for observation, and these have been added to the catalog. An online version of this catalog with downloadable content and visualization tools is maintained at http://keplerEBs.villanova.edu.

  20. From Binaries to Triples

    NASA Astrophysics Data System (ADS)

    Freismuth, T.; Tokovinin, A.

    2002-12-01

    About 10% of all binary systems are close binaries (P<1000 days). Among those with P<10d, over 40% are known to belong to higher-multiplicity systems (triples, quadruples, etc.). Do ALL close systems have tertiary companions? For a selection of 12 nearby, and apparently "single" close binaries with solar-mass dwarf primary components from the 8-th catalogue of spectroscopic binary orbits, images in the B and R filters were taken at the CTIO 0.9m telescope and suitable tertiary candidates were be identified on color-magnitude diagrams (CMDs). Of the 12 SBs, four were found to have tertiary candidates: HD 67084, HD 120734, HD 93486, and VV Mon. However, none of these candidates were found to be common proper motion companions. Follow up observations using adaptive optics reveal a companion to HD 148704. Future observations are planned.

  1. Double Degenerate Binary Systems

    SciTech Connect

    Yakut, K.

    2011-09-21

    In this study, angular momentum loss via gravitational radiation in double degenerate binary (DDB)systems (NS + NS, NS + WD, WD + WD, and AM CVn) is studied. Energy loss by gravitational waves has been estimated for each type of systems.

  2. Binary Minor Planets

    NASA Astrophysics Data System (ADS)

    Richardson, Derek C.; Walsh, Kevin J.

    2006-05-01

    A review of observations and theories regarding binary asteroids and binary trans-Neptunian objects [collectively, binary minor planets (BMPs)] is presented. To date, these objects have been discovered using a combination of direct imaging, lightcurve analysis, and radar. They are found throughout the Solar System, and present a challenge for theorists modeling their formation in the context of Solar System evolution. The most promising models invoke rotational disruption for the smallest, shortest-lived objects (the asteroids nearest to Earth), consistent with the observed fast rotation of these bodies; impacts for the larger, longer-lived asteroids in the main belt, consistent with the range of size ratios of their components and slower rotation rates; and mutual capture for the distant, icy, trans-Neptunian objects, consistent with their large component separations and near-equal sizes. Numerical simulations have successfully reproduced key features of the binaries in the first two categories; the third remains to be investigated in detail.

  3. Binaries in globular clusters

    NASA Technical Reports Server (NTRS)

    Hut, Piet; Mcmillan, Steve; Goodman, Jeremy; Mateo, Mario; Phinney, E. S.; Pryor, Carlton; Richer, Harvey B.; Verbunt, Frank; Weinberg, Martin

    1992-01-01

    Recent observations have shown that globular clusters contain a substantial number of binaries most of which are believed to be primordial. We discuss different successful optical search techniques, based on radial-velocity variables, photometric variables, and the positions of stars in the color-magnitude diagram. In addition, we review searches in other wavelengths, which have turned up low-mass X-ray binaries and more recently a variety of radio pulsars. On the theoretical side, we give an overview of the different physical mechanisms through which individual binaries evolve. We discuss the various simulation techniques which recently have been employed to study the effects of a primordial binary population, and the fascinating interplay between stellar evolution and stellar dynamics which drives globular-cluster evolution.

  4. Last orbits of binary strange quark stars

    SciTech Connect

    Limousin, Francois; Gourgoulhon, Eric; Gondek-Rosinska, Dorota

    2005-03-15

    We present the first relativistic calculations of the final phase of inspiral of a binary system consisting of two stars built predominantly of strange quark matter (strange quark stars). We study the precoalescing stage within the Isenberg-Wilson-Mathews approximation of general relativity using a multidomain spectral method. A hydrodynamical treatment is performed under the assumption that the flow is either rigidly rotating or irrotational, taking into account the finite density at the stellar surface--a distinctive feature with respect to the neutron star case. The gravitational-radiation driven evolution of the binary system is approximated by a sequence of quasiequilibrium configurations at fixed baryon number and decreasing separation. We find that the innermost stable circular orbit (ISCO) is given by an orbital instability both for synchronized and irrotational systems. This contrasts with neutron stars for which the ISCO is given by the mass-shedding limit in the irrotational case. The gravitational wave frequency at the ISCO, which marks the end of the inspiral phase, is found to be {approx}1400 Hz for two irrotational 1.35 M{sub {center_dot}} strange stars and for the MIT bag model of strange matter with massless quarks and a bag constant B=60 MeV fm{sup -3}. Detailed comparisons with binary neutrons star models, as well as with third order post-Newtonian point-mass binaries are given.

  5. Binary technetium halides

    NASA Astrophysics Data System (ADS)

    Johnstone, Erik Vaughan

    In this work, the synthetic and coordination chemistry as well as the physico-chemical properties of binary technetium (Tc) chlorides, bromides, and iodides were investigated. Resulting from these studies was the discovery of five new binary Tc halide phases: alpha/beta-TcCl3, alpha/beta-TcCl 2, and TcI3, and the reinvestigation of the chemistries of TcBr3 and TcX4 (X = Cl, Br). Prior to 2009, the chemistry of binary Tc halides was poorly studied and defined by only three compounds, i.e., TcF6, TcF5, and TcCl4. Today, ten phases are known (i.e., TcF6, TcF5, TcCl4, TcBr 4, TcBr3, TcI3, alpha/beta-TcCl3 and alpha/beta-TcCl2) making the binary halide system of Tc comparable to those of its neighboring elements. Technetium binary halides were synthesized using three methods: reactions of the elements in sealed tubes, reactions of flowing HX(g) (X = Cl, Br, and I) with Tc2(O2CCH3)4Cl2, and thermal decompositions of TcX4 (X = Cl, Br) and alpha-TcCl 3 in sealed tubes under vacuum. Binary Tc halides can be found in various dimensionalities such as molecular solids (TcF6), extended chains (TcF5, TcCl4, alpha/beta-TcCl2, TcBr 3, TcI3), infinite layers (beta-TcCl3), and bidimensional networks of clusters (alpha-TcCl3); eight structure-types with varying degrees of metal-metal interactions are now known. The coordination chemistry of Tc binary halides can resemble that of the adjacent elements: molybdenum and ruthenium (beta-TcCl3, TcBr3, TcI 3), rhenium (TcF5, alpha-TcCl3), platinum (TcCl 4, TcBr4), or can be unique (alpha-TcCl2 and beta-TcCl 2) in respect to other known transition metal binary halides. Technetium binary halides display a range of interesting physical properties that are manifested from their electronic and structural configurations. The thermochemistry of binary Tc halides is extensive. These compounds can selectively volatilize, decompose, disproportionate, or convert to other phases. Ultimately, binary Tc halides may find application in the nuclear fuel

  6. Binary-Symmetry Detection

    NASA Technical Reports Server (NTRS)

    Lopez, Hiram

    1987-01-01

    Transmission errors for zeros and ones tabulated separately. Binary-symmetry detector employs psuedo-random data pattern used as test message coming through channel. Message then modulo-2 added to locally generated and synchronized version of test data pattern in same manner found in manufactured test sets of today. Binary symmetrical channel shows nearly 50-percent ones to 50-percent zeroes correspondence. Degree of asymmetry represents imbalances due to either modulation, transmission, or demodulation processes of system when perturbed by noise.

  7. X-ray binaries

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

  8. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  9. The X-ray binary, UW CMa

    NASA Technical Reports Server (NTRS)

    Heap, S. R.

    1982-01-01

    The UW CMa is a close, eclipsing binary composed of an O7f primary with a stron wind and a less luminous O-type companion. It was found that UW CMa a variable X-ray source, whose X-ray variations are in phase with its optical light curve. Since both components of the binary system are O stars, accretion by a compact object is ruled out as a mechanism for generating X-rays. The UW CMa represents a new class of X-ray binaries, in which X-rays result from the collision of a wind from one star with the surface or wind of the other star. It is hypothesised that the impact of a wind against a star generates a shock wave about 0.25 stellar radii above the stellar surface, and material behind the shock front, heated to bout 10 million degrees, radiates the X-ray apparent X-ray variability is due to its location between the two stars, where it undergoes eclipses. The high temperature region maintains an ionization cavity in the wind, as detected with IUE. The ionization cavity is the source of depletion of absorbing ions in the wind between the two stars.

  10. STELLAR COLLISIONS AND BLUE STRAGGLER STARS IN DENSE GLOBULAR CLUSTERS

    SciTech Connect

    Chatterjee, Sourav; Rasio, Frederic A.; Sills, Alison; Glebbeek, Evert

    2013-11-10

    Blue straggler stars (BSSs) are abundantly observed in all Galactic globular clusters (GGCs) where data exist. However, observations alone cannot reveal the relative importance of various formation channels or the typical formation times for this well-studied population of anomalous stars. Using a state-of-the-art Hénon-type Monte Carlo code that includes all relevant physical processes, we create 128 models with properties typical of the observed GGCs. These models include realistic numbers of single and binary stars, use observationally motivated initial conditions, and span large ranges in central density, concentration, binary fraction, and mass. Their properties can be directly compared with those of observed GGCs. We can easily identify the BSSs in our models and determine their formation channels and birth times. We find that for central densities above ∼10{sup 3} M{sub ☉} pc{sup –3}, the dominant formation channel is stellar collisions, while for lower density clusters, mass transfer in binaries provides a significant contribution (up to 60% in our models). The majority of these collisions are binary-mediated, occurring during three-body and four-body interactions. As a result, a strong correlation between the specific frequency of BSSs and the binary fraction in a cluster can be seen in our models. We find that the number of BSSs in the core shows only a weak correlation with the collision rate estimator Γ traditionally used by observers, in agreement with the latest Hubble Space Telescope Advanced Camera for Surveys data. Using an idealized 'full mixing' prescription for collision products, our models indicate that the BSSs observed today may have formed several Gyr ago. However, denser clusters tend to have younger (∼1 Gyr) BSSs.

  11. Stellar Collisions and Blue Straggler Stars in Dense Globular Clusters

    NASA Astrophysics Data System (ADS)

    Chatterjee, Sourav; Rasio, Frederic A.; Sills, Alison; Glebbeek, Evert

    2013-11-01

    Blue straggler stars (BSSs) are abundantly observed in all Galactic globular clusters (GGCs) where data exist. However, observations alone cannot reveal the relative importance of various formation channels or the typical formation times for this well-studied population of anomalous stars. Using a state-of-the-art Hénon-type Monte Carlo code that includes all relevant physical processes, we create 128 models with properties typical of the observed GGCs. These models include realistic numbers of single and binary stars, use observationally motivated initial conditions, and span large ranges in central density, concentration, binary fraction, and mass. Their properties can be directly compared with those of observed GGCs. We can easily identify the BSSs in our models and determine their formation channels and birth times. We find that for central densities above ~103 M ⊙ pc-3, the dominant formation channel is stellar collisions, while for lower density clusters, mass transfer in binaries provides a significant contribution (up to 60% in our models). The majority of these collisions are binary-mediated, occurring during three-body and four-body interactions. As a result, a strong correlation between the specific frequency of BSSs and the binary fraction in a cluster can be seen in our models. We find that the number of BSSs in the core shows only a weak correlation with the collision rate estimator Γ traditionally used by observers, in agreement with the latest Hubble Space Telescope Advanced Camera for Surveys data. Using an idealized "full mixing" prescription for collision products, our models indicate that the BSSs observed today may have formed several Gyr ago. However, denser clusters tend to have younger (~1 Gyr) BSSs.

  12. Template bank for gravitational waveforms from coalescing binary black holes: Nonspinning binaries

    SciTech Connect

    Ajith, P.; Hewitson, M.; Babak, S.; Chen, Y.; Krishnan, B.; Whelan, J. T.; Dorband, N.; Pollney, D.; Rezzolla, L.; Sintes, A. M.; Bruegmann, B.; Hannam, M.; Husa, S.; Sperhake, U.; Diener, P.; Gonzalez, J.; Santamaria, L.; Thornburg, J.

    2008-05-15

    Gravitational waveforms from the inspiral and ring-down stages of the binary black-hole coalescences can be modeled accurately by approximation/perturbation techniques in general relativity. Recent progress in numerical relativity has enabled us to model also the nonperturbative merger phase of the binary black-hole coalescence problem. This enables us to coherently search for all three stages of the coalescence of nonspinning binary black holes using a single template bank. Taking our motivation from these results, we propose a family of template waveforms which can model the inspiral, merger, and ring-down stages of the coalescence of nonspinning binary black holes that follow quasicircular inspiral. This two-dimensional template family is explicitly parametrized by the physical parameters of the binary. We show that the template family is not only effectual in detecting the signals from black-hole coalescences, but also faithful in estimating the parameters of the binary. We compare the sensitivity of a search (in the context of different ground-based interferometers) using all three stages of the black-hole coalescence with other template-based searches which look for individual stages separately. We find that the proposed search is significantly more sensitive than other template-based searches for a substantial mass range, potentially bringing about remarkable improvement in the event rate of ground-based interferometers. As part of this work, we also prescribe a general procedure to construct interpolated template banks using nonspinning black-hole waveforms produced by numerical relativity.

  13. Molecular dynamics simulation of energy exchanges during hydrogen collision with graphite sheets

    SciTech Connect

    Sun Jizhong; Li Shouyang; Wang Dezhen; Stirner, Thomas; Chen Junlin

    2010-06-15

    Experiments show that the energy of particles incident on divertor plates in fusion devices seldom exceeds 100 eV. Trim code and its variants are not suitable to predict the sputtering yield of carbon-based divertor plates for this energy range and, therefore, a dynamic model, taking into account the C-H bond formation and breaking, and the structure of carbon, is needed. In this paper, the molecular dynamics method is employed to investigate collision processes between incident hydrogen atoms and a graphene sheet. The simulation results demonstrate that the collision processes cannot be adequately described by a simple binary approximation. The energy transfer from the projectile to the graphite sheet exhibits a very complicated behavior when the kinetic energy of the incident hydrogen atom is below 30 eV, strongly depending on the impact position. When its kinetic energy is lower than 0.35 eV, the incident hydrogen is always reflected back from the single, perfect graphite sheet; when its kinetic energy is higher than 0.35 eV, then whether the incident particle penetrates the graphite sheet, is reflected back or is adsorbed depends on the impact position. In certain areas of the graphite sheet, either adsorption or reflection of an incident hydrogen atom can occur in two different energy ranges.

  14. 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.

  15. Inelastic transitions in slow heavy-particle atomic collisions

    SciTech Connect

    Krstic, P. S.; Reinhold, C. O.; Burgdo''rfer, J.

    2001-05-01

    It is a generally held belief that inelastic transition probabilities and cross sections in slow, nearly adiabatic atomic collisions decrease exponentially with the inverse of the collision velocity v [i.e., {sigma}{proportional_to}exp(-const/v)]. This notion is supported by the Landau-Zener approximation and the hidden crossings approximation. We revisit the adiabatic limit of ion-atom collisions and show that for very slow collisions radial transitions are dominated by the topology of the branch points of the radial velocity rather than the branch points of the energy eigensurface. This can lead to a dominant power-law dependence of inelastic cross sections, {sigma}{proportional_to}v{sup n}. We illustrate the interplay between different contributions to the transition probabilities in a one-dimensional collision system for which the exact probabilities can be obtained from a direct numerical solution of the time-dependent Scho''dinger equation.

  16. Deconfinement phase transition in an expanding quark system in the relaxation time approximation

    NASA Astrophysics Data System (ADS)

    Yang, Zhenwei; Zhuang, Pengfei

    2004-03-01

    We investigated the effects of nonequilibrium and collision terms on the deconfinement phase transition of an expanding quark system in Friedberg-Lee model in relaxation time approximation. By calculating the effective quark potential, the critical temperature of the phase transition is dominated by the mean field, while the collisions among quarks and mesons change the time structure of the phase transition significantly.

  17. A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, Delta Orionis Aa. II. X-Ray Variability

    NASA Technical Reports Server (NTRS)

    Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Naze, Y.; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.; Hamaguchi, K.; Gull, T.

    2015-01-01

    We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral data set of the delta Ori Aa binary system. The four observations, obtained with Chandra ACIS (Advanced CCD Imaging Spectrometer) HETGS (High Energy Transmission Grating), have a total exposure time approximately equal to 479 kiloseconds and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range of 5-25 angstroms is confirmed, with a maximum amplitude of about plus or minus15 percent within a single approximately equal to125 kiloseconds observation. Periods of 4.76 and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in the flux level throughout the nine-day observational campaign. Using 40 kiloseconds contiguous spectra derived from the original observations, we investigate the variability of emission line parameters and ratios. Several emission lines are shown to be variable, including S (sub XV), Si (sub XIII), and Ne (sub IX). For the first time, variations of the X-ray emission line widths as a function of the binary phase are found in a binary system, with the smallest widths at phi = 0.0 when the secondary delta Ori Aa2 is at the inferior conjunction. Using 3D hydrodynamic modeling of the interacting winds, we relate the emission line width variability to the presence of a wind cavity created by a wind-wind collision, which is effectively void of embedded wind shocks and is carved out of the X-ray-producing primary wind, thus producing phase-locked X-ray variability.

  18. Multicriteria approximation through decomposition

    SciTech Connect

    Burch, C.; Krumke, S.; Marathe, M.; Phillips, C.; Sundberg, E.

    1998-06-01

    The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of their technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. Their method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) the authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing; (2) they also show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.

  19. Multicriteria approximation through decomposition

    SciTech Connect

    Burch, C. |; Krumke, S.; Marathe, M.; Phillips, C.; Sundberg, E. |

    1997-12-01

    The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of the technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. The method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) The authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing. (2) They show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.

  20. On Stochastic Approximation.

    ERIC Educational Resources Information Center

    Wolff, Hans

    This paper deals with a stochastic process for the approximation of the root of a regression equation. This process was first suggested by Robbins and Monro. The main result here is a necessary and sufficient condition on the iteration coefficients for convergence of the process (convergence with probability one and convergence in the quadratic…

  1. Approximating Integrals Using Probability

    ERIC Educational Resources Information Center

    Maruszewski, Richard F., Jr.; Caudle, Kyle A.

    2005-01-01

    As part of a discussion on Monte Carlo methods, which outlines how to use probability expectations to approximate the value of a definite integral. The purpose of this paper is to elaborate on this technique and then to show several examples using visual basic as a programming tool. It is an interesting method because it combines two branches of…

  2. First law of mechanics for compact binaries on eccentric orbits

    NASA Astrophysics Data System (ADS)

    Le Tiec, Alexandre

    2015-10-01

    Using the canonical Arnowitt-Deser-Misner Hamiltonian formalism, a "first law of mechanics" is established for binary systems of point masses moving along generic stable bound (eccentric) orbits. This relationship is checked to hold within the post-Newtonian approximation to general relativity, up to third order. Several applications are discussed, including the use of gravitational self-force results to inform post-Newtonian theory and the effective one-body model for eccentric-orbit compact binaries.

  3. Planetary Formation and Dynamics in Binary Systems

    NASA Astrophysics Data System (ADS)

    Xie, J. W.

    2013-01-01

    As of today, over 500 exoplanets have been detected since the first exoplanet was discovered around a solar-like star in 1995. The planets in binaries could be common as stars are usually born in binary or multiple star systems. Although current observations show that the planet host rate in multiple star systems is around 17%, this fraction should be considered as a lower limit because of noticeable selection effects against binaries in planet searches. Most of the current known planet-bearing binary systems are S-types, meaning the companion star acts as a distant satellite, typically orbiting the inner star-planet system over 100 AU away. Nevertheless, there are four systems with a smaller separation of 20 AU, including the Gamma Cephei, GJ 86, HD 41004, and HD 196885. In addition to the planets in circumprimary (S-type) orbits discussed above, planets in circumbinary (P-type) orbits have been found in only two systems. In this thesis, we mainly study the planet formation in the S-type binary systems. In chapter 1, we first summarize current observational facts of exoplanets both in single-star and binary systems, then review the theoretical models of planet formation, with special attention to the application in binary systems. Perturbative effects from stellar companions render the planet formation process in binary systems even more complex than that in single-star systems. The perturbations from a binary companion can excite planetesimal orbits, and increase their mutual impact velocities to the values that might exceed their escape velocity or even the critical velocity for the onset of eroding collisions. The intermediate stage of the formation process---from planetesimals to planetary embryos---is thus the most problematic. In the following chapters, we investigate whether and how the planet formation goes through such a problematic stage. In chapter 2, we study the effects of gas dissipation on the planetesimals' mutual accretion. We find that in a

  4. Formation of Short-Period Binary Pulsars in Globular Clusters.

    PubMed

    Rasio; Pfahl; Rappaport

    2000-03-20

    We present a new dynamical scenario for the formation of short-period binary millisecond pulsars in globular clusters. Our work is motivated by the recent observations of 20 radio pulsars in 47 Tuc. In a dense cluster such as 47 Tuc, most neutron stars acquire binary companions through exchange interactions with primordial binaries. The resulting systems have semimajor axes in the range approximately 0.1-1 AU and neutron star companion masses approximately 1-3 M middle dot in circle. For many of these systems, we find that when the companion evolves off the main sequence and fills its Roche lobe, the subsequent mass transfer is dynamically unstable. This leads to a common envelope phase and the formation of short-period neutron star-white dwarf binaries. For a significant fraction of these binaries, the decay of the orbit due to gravitational radiation will be followed by a period of stable mass transfer driven by a combination of gravitational radiation and tidal heating of the companion. The properties of the resulting short-period binaries match well those of observed binary pulsars in 47 Tuc.

  5. Dynamics of Compact Binaries in Effective Field Theory Formalism

    NASA Astrophysics Data System (ADS)

    Perrodin, Delphine

    2010-02-01

    Coalescing compact binaries are predicted to be powerful emitters of gravitational waves, and provide a strong gravity environment ideal for the testing of gravity theories. We study the gravitational dynamics in the early inspiral phase of coalescing compact binaries using Non-Relativistic General Relativity (NRGR) - an effective field theory formalism based on the Post-Newtonian approximation to General Relativity, but which provides a consistent lagrangian framework and a systematic way in which to study binary dynamics and gravitational wave emission. We calculate in this framework the spin-orbit correction to the newtonian potential at 2.5 PN. )

  6. CIRCUMBINARY MAGNETOHYDRODYNAMIC ACCRETION INTO INSPIRALING BINARY BLACK HOLES

    SciTech Connect

    Noble, Scott C.; Mundim, Bruno C.; Nakano, Hiroyuki; Campanelli, Manuela; Zlochower, Yosef; Krolik, Julian H.; Yunes, Nicolas

    2012-08-10

    We have simulated the magnetohydrodynamic evolution of a circumbinary disk surrounding an equal-mass binary comprising two non-spinning black holes during the period in which the disk inflow time is comparable to the binary evolution time due to gravitational radiation. Both the changing spacetime and the binary orbital evolution are described by an innovative technique utilizing high-order post-Newtonian approximations. Prior to the beginning of the inspiral, the structure of the circumbinary disk is predicted well by extrapolation from Newtonian results: a gap of roughly two binary separation radii is cleared, and matter piles up at the outer edge of this gap as inflow is retarded by torques exerted by the binary; the accretion rate is roughly half its value at large radius. During inspiral, the inner edge of the disk initially moves inward in coordination with the shrinking binary, but-as the orbital evolution accelerates-the inward motion of the disk edge falls behind the rate of binary compression. In this stage, the binary torque falls substantially, but the accretion rate decreases by only 10%-20%. When the binary separation is tens of gravitational radii, the rest-mass efficiency of disk radiation is a few percent, suggesting that supermassive binary black holes could be very luminous at this stage of their evolution. Inner disk heating is modulated at a beat frequency comparable to the binary orbital frequency. However, a disk with sufficient surface density to be luminous may be optically thick, suppressing periodic modulation of the luminosity.

  7. 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.

  8. Optimizing the Zeldovich approximation

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.; Pellman, Todd F.; Shandarin, Sergei F.

    1994-01-01

    We have recently learned that the Zeldovich approximation can be successfully used for a far wider range of gravitational instability scenarios than formerly proposed; we study here how to extend this range. In previous work (Coles, Melott and Shandarin 1993, hereafter CMS) we studied the accuracy of several analytic approximations to gravitational clustering in the mildly nonlinear regime. We found that what we called the 'truncated Zeldovich approximation' (TZA) was better than any other (except in one case the ordinary Zeldovich approximation) over a wide range from linear to mildly nonlinear (sigma approximately 3) regimes. TZA was specified by setting Fourier amplitudes equal to zero for all wavenumbers greater than k(sub nl), where k(sub nl) marks the transition to the nonlinear regime. Here, we study the cross correlation of generalized TZA with a group of n-body simulations for three shapes of window function: sharp k-truncation (as in CMS), a tophat in coordinate space, or a Gaussian. We also study the variation in the crosscorrelation as a function of initial truncation scale within each type. We find that k-truncation, which was so much better than other things tried in CMS, is the worst of these three window shapes. We find that a Gaussian window e(exp(-k(exp 2)/2k(exp 2, sub G))) applied to the initial Fourier amplitudes is the best choice. It produces a greatly improved crosscorrelation in those cases which most needed improvement, e.g. those with more small-scale power in the initial conditions. The optimum choice of kG for the Gaussian window is (a somewhat spectrum-dependent) 1 to 1.5 times k(sub nl). Although all three windows produce similar power spectra and density distribution functions after application of the Zeldovich approximation, the agreement of the phases of the Fourier components with the n-body simulation is better for the Gaussian window. We therefore ascribe the success of the best-choice Gaussian window to its superior treatment

  9. Applied Routh approximation

    NASA Technical Reports Server (NTRS)

    Merrill, W. C.

    1978-01-01

    The Routh approximation technique for reducing the complexity of system models was applied in the frequency domain to a 16th order, state variable model of the F100 engine and to a 43d order, transfer function model of a launch vehicle boost pump pressure regulator. The results motivate extending the frequency domain formulation of the Routh method to the time domain in order to handle the state variable formulation directly. The time domain formulation was derived and a characterization that specifies all possible Routh similarity transformations was given. The characterization was computed by solving two eigenvalue-eigenvector problems. The application of the time domain Routh technique to the state variable engine model is described, and some results are given. Additional computational problems are discussed, including an optimization procedure that can improve the approximation accuracy by taking advantage of the transformation characterization.

  10. Topics in Metric Approximation

    NASA Astrophysics Data System (ADS)

    Leeb, William Edward

    This thesis develops effective approximations of certain metrics that occur frequently in pure and applied mathematics. We show that distances that often arise in applications, such as the Earth Mover's Distance between two probability measures, can be approximated by easily computed formulas for a wide variety of ground distances. We develop simple and easily computed characterizations both of norms measuring a function's regularity -- such as the Lipschitz norm -- and of their duals. We are particularly concerned with the tensor product of metric spaces, where the natural notion of regularity is not the Lipschitz condition but the mixed Lipschitz condition. A theme that runs throughout this thesis is that snowflake metrics (metrics raised to a power less than 1) are often better-behaved than ordinary metrics. For example, we show that snowflake metrics on finite spaces can be approximated by the average of tree metrics with a distortion bounded by intrinsic geometric characteristics of the space and not the number of points. Many of the metrics for which we characterize the Lipschitz space and its dual are snowflake metrics. We also present applications of the characterization of certain regularity norms to the problem of recovering a matrix that has been corrupted by noise. We are able to achieve an optimal rate of recovery for certain families of matrices by exploiting the relationship between mixed-variable regularity conditions and the decay of a function's coefficients in a certain orthonormal basis.

  11. First-principles binary diffusion coefficients for H, H₂, and four normal alkanes + N₂.

    PubMed

    Jasper, Ahren W; Kamarchik, Eugene; Miller, James A; Klippenstein, Stephen J

    2014-09-28

    Collision integrals related to binary (dilute gas) diffusion are calculated classically for six species colliding with N2. The most detailed calculations make no assumptions regarding the complexity of the potential energy surface, and the resulting classical collision integrals are in excellent agreement with previous semiclassical results for H + N2 and H2 + N2 and with recent experimental results for CnH(2n+2) + N2, n = 2-4. The detailed classical results are used to test the accuracy of three simplifying assumptions typically made when calculating collision integrals: (1) approximating the intermolecular potential as isotropic, (2) neglecting the internal structure of the colliders (i.e., neglecting inelasticity), and (3) employing unphysical R(-12) repulsive interactions. The effect of anisotropy is found to be negligible for H + N2 and H2 + N2 (in agreement with previous quantum mechanical and semiclassical results for systems involving atomic and diatomic species) but is more significant for larger species at low temperatures. For example, the neglect of anisotropy decreases the diffusion coefficient for butane + N2 by 15% at 300 K. The neglect of inelasticity, in contrast, introduces only very small errors. Approximating the repulsive wall as an unphysical R(-12) interaction is a significant source of error at all temperatures for the weakly interacting systems H + N2 and H2 + N2, with errors as large as 40%. For the normal alkanes in N2, which feature stronger interactions, the 12/6 Lennard-Jones approximation is found to be accurate, particularly at temperatures above ∼700 K where it predicts the full-dimensional result to within 5% (although with somewhat different temperature dependence). Overall, the typical practical approach of assuming isotropic 12/6 Lennard-Jones interactions is confirmed to be suitable for combustion applications except for weakly interacting systems, such as H + N2. For these systems, anisotropy and inelasticity can safely be

  12. First-principles binary diffusion coefficients for H, H2 and four normal alkanes + N2

    DOE PAGES

    Jasper, Ahren W.; Kamarchik, Eugene; Miller, James A.; ...

    2014-09-30

    Collision integrals related to binary (dilute gas) diffusion are calculated classically for six species colliding with N2. The most detailed calculations make no assumptions regarding the complexity of the potential energy surface, and the resulting classical collision integrals are in excellent agreement with previous semiclassical results for H + N2 and H2 + N2 and with recent experimental results for C n H2n+2 + N2, n = 2–4. The detailed classical results are used to test the accuracy of three simplifying assumptions typically made when calculating collision integrals: (1) approximating the intermolecular potential as isotropic, (2) neglecting the internal structuremore » of the colliders (i.e., neglecting inelasticity), and (3) employing unphysical R–12 repulsive interactions. The effect of anisotropy is found to be negligible for H + N2 and H2 + N2 (in agreement with previous quantum mechanical and semiclassical results for systems involving atomic and diatomic species) but is more significant for larger species at low temperatures. For example, the neglect of anisotropy decreases the diffusion coefficient for butane + N2 by 15% at 300 K. The neglect of inelasticity, in contrast, introduces only very small errors. Approximating the repulsive wall as an unphysical R–12 interaction is a significant source of error at all temperatures for the weakly interacting systems H + N2 and H2 + N2, with errors as large as 40%. For the normal alkanes in N2, which feature stronger interactions, the 12/6 Lennard–Jones approximation is found to be accurate, particularly at temperatures above –700 K where it predicts the full-dimensional result to within 5% (although with somewhat different temperature dependence). Overall, the typical practical approach of assuming isotropic 12/6 Lennard–Jones interactions is confirmed to be suitable for combustion applications except for weakly interacting systems, such as H + N2. For these systems, anisotropy and inelasticity

  13. Binary and Millisecond Pulsars.

    PubMed

    Lorimer, Duncan R

    2008-01-01

    We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1800. There are now 83 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 140 pulsars in 26 of the Galactic globular clusters. Recent highlights include the discovery of the young relativistic binary system PSR J1906+0746, a rejuvination in globular cluster pulsar research including growing numbers of pulsars with masses in excess of 1.5 M⊙, a precise measurement of relativistic spin precession in the double pulsar system and a Galactic millisecond pulsar in an eccentric (e = 0.44) orbit around an unevolved companion.

  14. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, G.P.; Zhao, J.; Feng, Z.

    1996-12-03

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered. 3 figs.

  15. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, Gerald P.; Zhao, Jianmin; Feng, Zhen

    1996-01-01

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered.

  16. Measured and calculated SF-6 collision and swarm ion transport data in SF6 -Ar and SF6 -Xe mixtures.

    PubMed

    Benhenni, M; de Urquijo, J; Yousfi, M; Hernandez-Avila, J L; Merbahi, N; Hinojosa, G; Eichwald, O

    2005-03-01

    The measurement of the mobility of SF-6 in the mixtures SF6 -Ar and SF6 -Xe is reported over the density-reduced electric field strength E/N 1-180 Td (1 Townsend = 10(-17) V cm(2)), from a time-resolved pulsed Townsend technique. Simultaneously, the mobility of SF-6 in the same binary mixtures has been calculated from a set of collision cross sections for SF-6 -Ar, SF-6 -Xe, and SF-6 - SF6 using a Monte Carlo simulation procedure for ion transport. The good agreement between measured and calculated mobilities in these gas mixtures has led us to conclude that the validation of our cross section sets is confirmed. The elastic collision cross section, a predominant process for ion energies lower than about 10 eV, was determined from a semiclassical JWKB approximation using a rigid core potential model for the ion-neutral systems under consideration. This elastic cross section was then added to several other inelastic collision cross sections found in the literature for ion conversion, electron detachment of SF-6 and charge transfer. Moreover, the calculations of the mobility and the ratios of the transverse and longitudinal diffusion coefficients to the mobility were extended into a much wider E/N range from 1 to 4000 Td. Additionally, we have also calculated the energy distribution functions and the reaction coefficients for ion conversion and electron detachment. Finally, we have shown that the range of validity for the calculation of the mobility in gas mixtures from Blanc's law is only valid for the low E/N region, where the interaction is dominated by elastic collisions and the ion distribution function remains essentially Maxwellian.

  17. On Filtered Binary Processes.

    DTIC Science & Technology

    1984-11-01

    BINARY PROCESSES 12. PERSONAL AUTHOR(S) R.F. Pawula and S.O. Rice 13s. TYPE OF REPORT 13b. TIME COVERED.!14 DATE OF REPORT MY,, o.. Day) 15. PAGE COUNT...APR EDITION OF I JAN 73 IS OBSOLETE. UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE eO R.TR. 85-0055 On Filtered Binary Processes R . F. Pawula ...is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation ",."/ hereon. R. F. Pawula is with

  18. Binary and Millisecond Pulsars.

    PubMed

    Lorimer, Duncan R

    2005-01-01

    We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1700. There are now 80 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 103 pulsars in 24 of the Galactic globular clusters. Recent highlights have been the discovery of the first ever double pulsar system and a recent flurry of discoveries in globular clusters, in particular Terzan 5.

  19. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1996-01-01

    We present preliminary results of our implementation of a novel electrophoresis separation technique: Binary Oscillatory Cross flow Electrophoresis (BOCE). The technique utilizes the interaction of two driving forces, an oscillatory electric field and an oscillatory shear flow, to create an active binary filter for the separation of charged species. Analytical and numerical studies have indicated that this technique is capable of separating proteins with electrophoretic mobilities differing by less than 10%. With an experimental device containing a separation chamber 20 cm long, 5 cm wide, and 1 mm thick, an order of magnitude increase in throughput over commercially available electrophoresis devices is theoretically possible.

  20. Light-assisted collisions in ultracold Tm atoms

    NASA Astrophysics Data System (ADS)

    Cojocaru, I. S.; Pyatchenkov, S. V.; Snigirev, S. A.; Luchnikov, I. A.; Kalganova, E. S.; Vishnyakova, G. A.; Kublikova, D. N.; Bushmakin, V. S.; Davletov, E. T.; Tsyganok, V. V.; Belyaeva, O. V.; Khoroshilov, A.; Sorokin, V. N.; Sukachev, D. D.; Akimov, A. V.

    2017-01-01

    We studied light-assisted collisions of Tm atoms in a magneto-optical trap (MOT), working on a weak cooling transition at 530.7 nm [4 f13(F2o) 6 s2,J =7 /2 ,F =4 to 4 f12(H36) 5 d5 /26 s2,J =9 /2 ,F =5 ]. We observed a strong influence from radiation trapping and light-assisted collisions on the dynamics of this trap. We carefully separated these two contributions and measured the binary loss rate constant at different laser powers and detuning frequencies near the cooling transition. Analyzing losses from the MOT, we found the light-assisted inelastic binary loss rate constant to reach values of up to β =10-9c m3/s and gave the upper bound on a branching ratio k <0.8 ×10-6 for the 530.7 nm transition.

  1. Workshop on Colliding Winds in Binary Stars to Honor Jorge Sahade

    NASA Astrophysics Data System (ADS)

    Niemela, Virpi; Morrell, Nidia; Pismis, Paris; Torres-Peimbert, Silvia

    1996-12-01

    Topics considered include: the beginning of the story; mass flow in and out of close binaries; winds of massive, main sequence close binaries; chromospheric activity, stellar winds and red stragglers; uv observations of mass transfer in algols; the circumstellar matter in pre-supernovae of type Ia; observations of colliding winds in O-type binaries; colliding winds in massive binaries involving Wolf-Rayet stars; episodic dust formation by Wolf-Rayet stars: smoke signals from colliding winds; x-ray emission from colliding wind binaries; colliding stellar winds: a new method of determining mass-loss rates via x-ray spectroscopy; sudden radiative braking in colliding hot-star winds; optical observations of colliding winds in gamma2 velorum; left overs for dinner; HD 5980: the Wolf-Rayet binary that became a luminous blue variable; the erupting Wolf-Rayet binary HD 5980 in the small magellanic cloud: spectral transition from B1.5Ia(+) to WN6 and the accompanying light curve; the elliptic orbit of the WR binary system CV serpentis; evidence for colliding winds in WR 146; is there wind-wind collision in WR 141 (HD 193928)?; search for interacting winds in the WN7 + O binary; line formation in CH Cyg: a symbiotic binary; period analysis of radial velocity of pleione; H(alpha) detection of colliding winds in O-type binaries; HD 5980 in the infrared; photometric and polarimetric observations of the Wolf-Rayet eclipsing binary HD 5980 in the small magellanic cloud, and analysis of linear polarization in two Wolf-Rayet binary systems.

  2. Compact Collision Kernels for Hard Sphere and Coulomb Cross Sections; Fokker-Planck Coefficients

    SciTech Connect

    Chang Yongbin; Shizgal, Bernie D.

    2008-12-31

    A compact collision kernel is derived for both hard sphere and Coulomb cross sections. The difference between hard sphere interaction and Coulomb interaction is characterized by a parameter {eta}. With this compact collision kernel, the calculation of Fokker-Planck coefficients can be done for both the Coulomb and hard sphere interactions. The results for arbitrary order Fokker-Planck coefficients are greatly simplified. An alternate form for the Coulomb logarithm is derived with concern to the temperature relaxation in a binary plasma.

  3. Approximate option pricing

    SciTech Connect

    Chalasani, P.; Saias, I.; Jha, S.

    1996-04-08

    As increasingly large volumes of sophisticated options (called derivative securities) are traded in world financial markets, determining a fair price for these options has become an important and difficult computational problem. Many valuation codes use the binomial pricing model, in which the stock price is driven by a random walk. In this model, the value of an n-period option on a stock is the expected time-discounted value of the future cash flow on an n-period stock price path. Path-dependent options are particularly difficult to value since the future cash flow depends on the entire stock price path rather than on just the final stock price. Currently such options are approximately priced by Monte carlo methods with error bounds that hold only with high probability and which are reduced by increasing the number of simulation runs. In this paper the authors show that pricing an arbitrary path-dependent option is {number_sign}-P hard. They show that certain types f path-dependent options can be valued exactly in polynomial time. Asian options are path-dependent options that are particularly hard to price, and for these they design deterministic polynomial-time approximate algorithms. They show that the value of a perpetual American put option (which can be computed in constant time) is in many cases a good approximation to the value of an otherwise identical n-period American put option. In contrast to Monte Carlo methods, the algorithms have guaranteed error bounds that are polynormally small (and in some cases exponentially small) in the maturity n. For the error analysis they derive large-deviation results for random walks that may be of independent interest.

  4. Approximate Qualitative Temporal Reasoning

    DTIC Science & Technology

    2001-01-01

    i.e., their boundaries can be placed in such a way that they coincide with the cell boundaries of the appropriate partition of the time-line. (Think of...respect to some appropriate partition of the time-line. For example, I felt well on Saturday. When I measured my temperature I had a fever on Monday and on...Bittner / Approximate Qualitative Temporal Reasoning 49 [27] I. A. Goralwalla, Y. Leontiev , M. T. Özsu, D. Szafron, and C. Combi. Temporal granularity for

  5. 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.

  6. 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…

  7. Binary coding for hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chang, Chein-I.; Chang, Chein-Chi; Lin, Chinsu

    2004-10-01

    Binary coding is one of simplest ways to characterize spectral features. One commonly used method is a binary coding-based image software system, called Spectral Analysis Manager (SPAM) for remotely sensed imagery developed by Mazer et al. For a given spectral signature, the SPAM calculates its spectral mean and inter-band spectral difference and uses them as thresholds to generate a binary code word for this particular spectral signature. Such coding scheme is generally effective and also very simple to implement. This paper revisits the SPAM and further develops three new SPAM-based binary coding methods, called equal probability partition (EPP) binary coding, halfway partition (HP) binary coding and median partition (MP) binary coding. These three binary coding methods along with the SPAM well be evaluated for spectral discrimination and identification. In doing so, a new criterion, called a posteriori discrimination probability (APDP) is also introduced for performance measure.

  8. Eclipsing Binary Update, No. 2.

    NASA Astrophysics Data System (ADS)

    Williams, D. B.

    1996-01-01

    Contents: 1. Wrong again! The elusive period of DHK 41. 2. Stars observed and not observed. 3. Eclipsing binary chart information. 4. Eclipsing binary news and notes. 5. A note on SS Arietis. 6. Featured star: TX Ursae Majoris.

  9. 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.

  10. SELF-REGULATED SHOCKS IN MASSIVE STAR BINARY SYSTEMS

    SciTech Connect

    Parkin, E. R.; Sim, S. A. E-mail: s.sim@qub.ac.uk

    2013-04-20

    In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady-state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, L{sub X}, remains largely unaltered, with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind driving, we term this scenario as self-regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the momenta of the two winds are significantly different. Furthermore, the excessive levels of X-ray ionization close to the shocks completely suppress the line force, and we suggest that this may render radiative braking less effective. Comparisons of model results against observations reveal reasonable agreement in terms of log (L{sub X}/L{sub bol}). The inclusion of self-regulated shocks improves the match for kT values in roughly equal wind momenta systems, but there is a systematic offset for systems with unequal wind momenta (if considered to be a wind-photosphere collision).

  11. 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.

  12. Binary stars - Formation by fragmentation

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.

    1988-01-01

    Theories of binary star formation by capture, separate nuclei, fission and fragmentation are compared, assessing the success of theoretical attempts to explain the observed properties of main-sequence binary stars. The theory of formation by fragmentation is examined, discussing the prospects for checking the theory against observations of binary premain-sequence stars. It is concluded that formation by fragmentation is successful at explaining many of the key properties of main-sequence binary stars.

  13. Orbits For Sixteen Binaries

    NASA Astrophysics Data System (ADS)

    Cvetkovic, Z.; Novakovic, B.

    2006-12-01

    In this paper orbits for 13 binaries are recalculated and presented. The reason is that recent observations show higher residuals than the corresponding ephemerides calculated by using the orbital elements given in the Sixth Catalog of Orbits of Visual Binary Stars. The binaries studied were: WDS 00182+7257 = A 803, WDS 00335+4006 = HO 3, WDS 00583+2124 = BU 302, WDS 01011+6022 = A 926, WDS 01014+1155 = BU 867, WDS 01112+4113 = A 655, WDS 01361-2954 + HJ 3447, WDS 02333+5219 = STT 42 AB, WDS 04362+0814 = A 1840 AB, WDS 08017-0836 = A 1580, WDS 08277-0425 = A 550, WDS 17471+1742 = STF 2215 and WDS 18025+4414 = BU 1127 Aa-B. In addition, for three binaries - WDS 01532+1526 = BU 260, WDS 02563+7253 =STF 312 AB and WDS 05003+3924 = STT 92 AB - the orbital elements are calculated for the first time. In this paper the authors present not only the orbital elements, but the masses, dynamical parallaxes, absolute magnitudes and ephemerides for the next five years, as well.

  14. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  15. Numerically Solvable Model for Resonant Collisions of Electronswith Diatomic Molecules

    SciTech Connect

    Houfek, Karel; Rescigno, T.N.; McCurdy, C.W.

    2006-01-27

    We describe a simple model for electron-molecule collisions that has one nuclear and one electronic degree of freedom and that can be solved to arbitrarily high precision, without making the Born-Oppenheimer approximation, by employing a combination of the exterior complex scaling method and a finite-element implementation of the discrete variable representation. We compare exact cross sections for vibrational excitation and dissociative attachment with results obtained using the local complex potential approximation as commonly applied in the ''boomerang'' model, and suggest how this two-dimensional model can be used to test the underpinnings of contemporary nonlocal approximations to resonant collisions.

  16. Accreting Binary Populations in the Earlier Universe

    NASA Technical Reports Server (NTRS)

    Hornschemeier, Ann

    2010-01-01

    It is now understood that X-ray binaries dominate the hard X-ray emission from normal star-forming galaxies. Thanks to the deepest (2-4 Ms) Chandra surveys, such galaxies are now being studied in X-rays out to z approximates 4. Interesting X-ray stacking results (based on 30+ galaxies per redshift bin) suggest that the mean rest-frame 2-10 keV luminosity from z=3-4 Lyman break galaxies (LBGs), is comparable to the most powerful starburst galaxies in the local Universe. This result possibly indicates a similar production mechanism for accreting binaries over large cosmological timescales. To understand and constrain better the production of X-ray binaries in high-redshift LBGs, we have utilized XMM-Newton observations of a small sample of z approximates 0.1 GALEX-selected Ultraviolet-Luminous Galaxies (UVLGs); local analogs to high-redshift LBGs. Our observations enable us to study the X-ray emission from LBG-like galaxies on an individual basis, thus allowing us to constrain object-to-object variances in this population. We supplement these results with X-ray stacking constraints using the new 3.2 Ms Chandra Deep Field-South (completed spring 2010) and LBG candidates selected from HST, Swift UVOT, and ground-based data. These measurements provide new X-ray constraints that sample well the entire z=0-4 baseline

  17. Hierarchical Approximate Bayesian Computation

    PubMed Central

    Turner, Brandon M.; Van Zandt, Trisha

    2013-01-01

    Approximate Bayesian computation (ABC) is a powerful technique for estimating the posterior distribution of a model’s parameters. It is especially important when the model to be fit has no explicit likelihood function, which happens for computational (or simulation-based) models such as those that are popular in cognitive neuroscience and other areas in psychology. However, ABC is usually applied only to models with few parameters. Extending ABC to hierarchical models has been difficult because high-dimensional hierarchical models add computational complexity that conventional ABC cannot accommodate. In this paper we summarize some current approaches for performing hierarchical ABC and introduce a new algorithm called Gibbs ABC. This new algorithm incorporates well-known Bayesian techniques to improve the accuracy and efficiency of the ABC approach for estimation of hierarchical models. We then use the Gibbs ABC algorithm to estimate the parameters of two models of signal detection, one with and one without a tractable likelihood function. PMID:24297436

  18. Maximum noise-immunity of a digital communications channel with binary coding

    NASA Astrophysics Data System (ADS)

    Senderskii, V. A.; Strokov, V. V.

    1987-07-01

    The maximum noise-immunity of a digital comunications channel with binary coding is analyzed as a function of the coding rate. The investigation is carried out for two limiting cases: binary-continuous and binary symmetric channels. It is concluded that the results obtained can be used to estimate the degree to which the noise-immunity values of actual digital channels approximate the maximally possible values.

  19. Formation of Binaries at the Stage of Rarefied Preplanetesimals

    NASA Astrophysics Data System (ADS)

    Ipatov, Sergei I.

    2009-05-01

    Last years, new arguments in favor of the model of rarefied preplanetesimals - clumps have been found by several scientists. The models of binary formation due to the gravitational interactions or collisions of future binary components with an object (or objects) that were inside their Hill sphere, which were considered by several authors for solid objects, could be more effective for rarefied preplanetesimals. For example, due to almost circular heliocentric orbits, duration of their motion inside the Hill sphere could be longer and minimum distances could be smaller than for solid bodies. Some collided rarefied preplanetesimals had a greater density at distances closer to their centers, and sometimes there could be two centers of contraction inside the rotating preplanetesimal formed as a result of a collision of two rarefied preplanetesimals. The observed separation distance can characterize the sizes of contracted preplanetesimals. In particular, binaries with close masses separated by a large distance and with any value of the eccentricity of the orbit of the secondary component relative to the primary component could be formed. Most of rarefied preasteroids could contract into solid asteroids before they collided with other preasteroids. Formation of some binaries could be caused by that the angular momentum that they obtained at the stage of rarefied preplanetesimals was greater than that could exist for solid bodies. During contraction of a rotating rarefied preplanetesimal, some material could form a cloud (that transformed into a disk) of material moving around the contracting primary. One or several satellites of the primary could be formed from this cloud. The angular momentum of a discovered trans-Neptunian or asteroidal binary is smaller than the typical angular momentum of two identical rarefied preplanetesimals having the same total mass and encountering to the Hill sphere from circular heliocentric orbits (Ipatov S.I. 2009, LPSC XL, #1021).

  20. Redshift Factor and the First Law of Binary Black Hole Mechanics in Numerical Simulations.

    PubMed

    Zimmerman, Aaron; Lewis, Adam G M; Pfeiffer, Harald P

    2016-11-04

    The redshift factor z is an invariant quantity of fundamental interest in post-Newtonian and self-force descriptions of compact binaries. It connects different approximation schemes, and plays a central role in the first law of binary black hole mechanics, which links local quantities to asymptotic measures of energy and angular momentum in these systems. Through this law, the redshift factor is conjectured to have a close relation to the surface gravity of the event horizons of black holes in circular orbits. We propose and implement a novel method for extracting the redshift factor on apparent horizons in numerical simulations of quasicircular binary inspirals. Our results confirm the conjectured relationship between z and the surface gravity of the holes and that the first law holds to a remarkable degree for binary inspirals. The redshift factor enables tests of analytic predictions for z in spacetimes where the binary is only approximately circular, giving a new connection between analytic approximations and numerical simulations.

  1. Redshift Factor and the First Law of Binary Black Hole Mechanics in Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Zimmerman, Aaron; Lewis, Adam G. M.; Pfeiffer, Harald P.

    2016-11-01

    The redshift factor z is an invariant quantity of fundamental interest in post-Newtonian and self-force descriptions of compact binaries. It connects different approximation schemes, and plays a central role in the first law of binary black hole mechanics, which links local quantities to asymptotic measures of energy and angular momentum in these systems. Through this law, the redshift factor is conjectured to have a close relation to the surface gravity of the event horizons of black holes in circular orbits. We propose and implement a novel method for extracting the redshift factor on apparent horizons in numerical simulations of quasicircular binary inspirals. Our results confirm the conjectured relationship between z and the surface gravity of the holes and that the first law holds to a remarkable degree for binary inspirals. The redshift factor enables tests of analytic predictions for z in spacetimes where the binary is only approximately circular, giving a new connection between analytic approximations and numerical simulations.

  2. Entropy production in collisions of gravitational shock waves and of heavy ions

    SciTech Connect

    Gubser, Steven S.; Pufu, Silviu S.; Yarom, Amos

    2008-09-15

    We calculate the area of a marginally trapped surface formed by a head-on collision of gravitational shock waves in AdS{sub D}. We use this to obtain a lower bound on the entropy produced after the collision. A comparison to entropy production in heavy-ion collisions is included. We also discuss an O(D-2) remnant of conformal symmetry, which is present in a class of gravitational shockwave collisions in AdS{sub D} and which might be approximately realized (with D=5) in central heavy-ion collisions.

  3. Encoding of multi-alphabet sources by binary arithmetic coding

    NASA Astrophysics Data System (ADS)

    Guo, Muling; Oka, Takahumi; Kato, Shigeo; Kajiwara, Hiroshi; Kawamura, Naoto

    1998-12-01

    In case of encoding a multi-alphabet source, the multi- alphabet symbol sequence can be encoded directly by a multi- alphabet arithmetic encoder, or the sequence can be first converted into several binary sequences and then each binary sequence is encoded by binary arithmetic encoder, such as the L-R arithmetic coder. Arithmetic coding, however, requires arithmetic operations for each symbol and is computationally heavy. In this paper, a binary representation method using Huffman tree is introduced to reduce the number of arithmetic operations, and a new probability approximation for L-R arithmetic coding is further proposed to improve the coding efficiency when the probability of LPS (Least Probable Symbol) is near 0.5. Simulation results show that our proposed scheme has high coding efficacy and can reduce the number of coding symbols.

  4. Reading Watermarks from Printed Binary Images with a Camera Phone

    NASA Astrophysics Data System (ADS)

    Pramila, Anu; Keskinarkaus, Anja; Seppänen, Tapio

    In this paper, we propose a method for reading a watermark from a printed binary image with a camera phone. The watermark is a small binary image which is protected with (15, 11) Hamming error coding and embedded in the binary image by utilizing flippability scores of the pixels and block based relationships. The binary image is divided into blocks and fixed number of bits is embedded in each block. A frame is added around the image in order to overcome 3D distortions and lens distortions are corrected by calibrating the camera. The results obtained are encouraging and when the images were captured freehandedly by rotating the camera approximately -2 - 2 degrees, the amount of fully recovered watermarks was 96.3%.

  5. Countably QC-Approximating Posets

    PubMed Central

    Mao, Xuxin; Xu, Luoshan

    2014-01-01

    As a generalization of countably C-approximating posets, the concept of countably QC-approximating posets is introduced. With the countably QC-approximating property, some characterizations of generalized completely distributive lattices and generalized countably approximating posets are given. The main results are as follows: (1) a complete lattice is generalized completely distributive if and only if it is countably QC-approximating and weakly generalized countably approximating; (2) a poset L having countably directed joins is generalized countably approximating if and only if the lattice σc(L)op of all σ-Scott-closed subsets of L is weakly generalized countably approximating. PMID:25165730

  6. Planetesimal Accretion in Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Marzari, F.; Scholl, H.

    2000-11-01

    Planetesimal accretion in close binary systems is a complex process for the gravitational perturbations of the companion star on the planetesimal orbits. These perturbations excite high eccentricities that can halt the accumulation process of planetesimals into planets also in those regions around the star where stable planetary orbits would eventually be possible. However, the evolution of a planetesimal swarm is also affected by collisions and gas drag. In particular, gas drag combined with the secular perturbations of the secondary star forces a strong alignment of all the planetesimal periastra. Since periastra are also coupled to eccentricities via the secular perturbations of the companion, the orbits of the planetesimals, besides all being aligned, also have very close values of eccentricity. This orbital ``phasing'' strongly reduces the contribution of the eccentricity to the relative velocities between planetesimals, and the impact speeds are dominated by the Keplerian shear: accretion becomes possible. This behavior is not limited to small planetesimals but also affects bodies as large as 100 km in diameter. The effects of gas drag are in fact enhanced by the presence of the constant forced component in the orbital eccentricity of the planetesimals. We describe analytically the periastron alignment by using the secular equations developed by Heppenheimer, and we test the prediction of the theory with a numerical code that integrates the orbits of a swarm of planetesimals perturbed by gas drag and collisions. The gas density is assumed to decrease outward, and the collisions are modeled as inelastic. Our computations are focused on the α Centauri system, which is a good candidate for terrestrial planets as we will show. The impact velocities between planetesimals of different sizes are computed at progressively increasing distances from the primary star and are compared with estimates for the maximum velocity for accretion. According to our simulations in

  7. Microfluidic binary phase flow

    NASA Astrophysics Data System (ADS)

    Angelescu, Dan; Menetrier, Laure; Wong, Joyce; Tabeling, Patrick; Salamitou, Philippe

    2004-03-01

    We present a novel binary phase flow regime where the two phases differ substantially in both their wetting and viscous properties. Optical tracking particles are used in order to investigate the details of such multiphase flow inside capillary channels. We also describe microfluidic filters we have developed, capable of separating the two phases based on capillary pressure. The performance of the filters in separating oil-water emulsions is discussed. Binary phase flow has been previously used in microchannels in applications such as emulsion generation, enhancement of mixing and assembly of custom colloidal paticles. Such microfluidic systems are increasingly used in a number of applications spanning a diverse range of industries, such as biotech, pharmaceuticals and more recently the oil industry.

  8. Processing Of Binary Images

    NASA Astrophysics Data System (ADS)

    Hou, H. S.

    1985-07-01

    An overview of the recent progress in the area of digital processing of binary images in the context of document processing is presented here. The topics covered include input scan, adaptive thresholding, halftoning, scaling and resolution conversion, data compression, character recognition, electronic mail, digital typography, and output scan. Emphasis has been placed on illustrating the basic principles rather than descriptions of a particular system. Recent technology advances and research in this field are also mentioned.

  9. Binary image classification

    NASA Technical Reports Server (NTRS)

    Morris, Carl N.

    1987-01-01

    Motivated by the LANDSAT problem of estimating the probability of crop or geological types based on multi-channel satellite imagery data, Morris and Kostal (1983), Hill, Hinkley, Kostal, and Morris (1984), and Morris, Hinkley, and Johnston (1985) developed an empirical Bayes approach to this problem. Here, researchers return to those developments, making certain improvements and extensions, but restricting attention to the binary case of only two attributes.

  10. Double Eclipsing Binary Fitting

    NASA Astrophysics Data System (ADS)

    Cagas, P.; Pejcha, O.

    2012-06-01

    The parameters of the mutual orbit of eclipsing binaries that are physically connected can be obtained by precision timing of minima over time through light travel time effect, apsidal motion or orbital precession. This, however, requires joint analysis of data from different sources obtained through various techniques and with insufficiently quantified uncertainties. In particular, photometric uncertainties are often underestimated, which yields too small uncertainties in minima timings if determined through analysis of a χ2 surface. The task is even more difficult for double eclipsing binaries, especially those with periods close to a resonance such as CzeV344, where minima get often blended with each other. This code solves the double binary parameters simultaneously and then uses these parameters to determine minima timings (or more specifically O-C values) for individual datasets. In both cases, the uncertainties (or more precisely confidence intervals) are determined through bootstrap resampling of the original data. This procedure to a large extent alleviates the common problem with underestimated photometric uncertainties and provides a check on possible degeneracies in the parameters and the stability of the results. While there are shortcomings to this method as well when compared to Markov Chain Monte Carlo methods, the ease of the implementation of bootstrapping is a significant advantage.

  11. 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.

  12. 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.

  13. Exact linearized Coulomb collision operator in the moment expansion

    DOE PAGES

    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 collisionmore » 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.« less

  14. Properties of the Boltzmann equation in the classical approximation

    DOE PAGES

    Epelbaum, Thomas; Gelis, François; Tanji, Naoto; ...

    2014-12-30

    We examine the Boltzmann equation with elastic point-like scalar interactions in two different versions of the the classical approximation. Although solving numerically the Boltzmann equation with the unapproximated collision term poses no problem, this allows one to study the effect of the ultraviolet cutoff in these approximations. This cutoff dependence in the classical approximations of the Boltzmann equation is closely related to the non-renormalizability of the classical statistical approximation of the underlying quantum field theory. The kinetic theory setup that we consider here allows one to study in a much simpler way the dependence on the ultraviolet cutoff, since onemore » has also access to the non-approximated result for comparison.« less

  15. Properties of the Boltzmann equation in the classical approximation

    SciTech Connect

    Epelbaum, Thomas; Gelis, François; Tanji, Naoto; Wu, Bin

    2014-12-30

    We examine the Boltzmann equation with elastic point-like scalar interactions in two different versions of the the classical approximation. Although solving numerically the Boltzmann equation with the unapproximated collision term poses no problem, this allows one to study the effect of the ultraviolet cutoff in these approximations. This cutoff dependence in the classical approximations of the Boltzmann equation is closely related to the non-renormalizability of the classical statistical approximation of the underlying quantum field theory. The kinetic theory setup that we consider here allows one to study in a much simpler way the dependence on the ultraviolet cutoff, since one has also access to the non-approximated result for comparison.

  16. Binary asteroids in the near-Earth object population.

    PubMed

    Margot, J L; Nolan, M C; Benner, L A M; Ostro, S J; Jurgens, R F; Giorgini, J D; Slade, M A; Campbell, D B

    2002-05-24

    Radar images of near-Earth asteroid 2000 DP107 show that it is composed of an approximately 800-meter-diameter primary and an approximately 300-meter-diameter secondary revolving around their common center of mass. The orbital period of 1.755 +/- 0.007 days and semimajor axis of 2620 +/- 160 meters constrain the total mass of the system to 4.6 +/- 0.5 x 10(11) kilograms and the bulk density of the primary to 1.7 +/- 1.1 grams per cubic centimeter. This system and other binary near-Earth asteroids have spheroidal primaries spinning near the breakup point for strengthless bodies, suggesting that the binaries formed by spin-up and fission, probably as a result of tidal disruption during close planetary encounters. About 16% of near-Earth asteroids larger than 200 meters in diameter may be binary systems.

  17. 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.

  18. Binary-Signal Recovery

    NASA Technical Reports Server (NTRS)

    Griebeler, Elmer L.

    2011-01-01

    Binary communication through long cables, opto-isolators, isolating transformers, or repeaters can become distorted in characteristic ways. The usual solution is to slow the communication rate, change to a different method, or improve the communication media. It would help if the characteristic distortions could be accommodated at the receiving end to ease the communication problem. The distortions come from loss of the high-frequency content, which adds slopes to the transitions from ones to zeroes and zeroes to ones. This weakens the definition of the ones and zeroes in the time domain. The other major distortion is the reduction of low frequency, which causes the voltage that defines the ones or zeroes to drift out of recognizable range. This development describes a method for recovering a binary data stream from a signal that has been subjected to a loss of both higher-frequency content and low-frequency content that is essential to define the difference between ones and zeroes. The method makes use of the frequency structure of the waveform created by the data stream, and then enhances the characteristics related to the data to reconstruct the binary switching pattern. A major issue is simplicity. The approach taken here is to take the first derivative of the signal and then feed it to a hysteresis switch. This is equivalent in practice to using a non-resonant band pass filter feeding a Schmitt trigger. Obviously, the derivative signal needs to be offset to halfway between the thresholds of the hysteresis switch, and amplified so that the derivatives reliably exceed the thresholds. A transition from a zero to a one is the most substantial, fastest plus movement of voltage, and therefore will create the largest plus first derivative pulse. Since the quiet state of the derivative is sitting between the hysteresis thresholds, the plus pulse exceeds the plus threshold, switching the hysteresis switch plus, which re-establishes the data zero to one transition

  19. Ultracold sodium and rubidium mixtures: collisions, interactions and heteronuclear molecule formation

    SciTech Connect

    Raman, Chandra S

    2013-02-06

    This program centers on quantum gases of 23Na and 87Rb, with the goal of observing collisions and interactions in binary mixtures. In the current period our research has focused on single species interactions and dynamics with a 23Na Bose-Einstein condensate.

  20. VizieR Online Data Catalog: Statistical test on binary stars non-coevality (Valle+, 2016)

    NASA Astrophysics Data System (ADS)

    Valle, G.; Dell'Omodarme, M.; Valle, G.; Prada Moroni, P. G.; Degl'Innocenti, S.

    2016-01-01

    The table contains the W0.95 critical values, for the 1087 binary systems considered in the paper. Tha table also lists the parameters of the beta distributions approximating the empirical W distributions. (1 data file).

  1. Visual binary stars: data to investigate formation of binaries

    NASA Astrophysics Data System (ADS)

    Kovaleva,, D.; Malkov,, O.; Yungelson, L.; Chulkov, D.

    Statistics of orbital parameters of binary stars as well as statistics of their physical characteristics bear traces of star formation history. However, statistical investigations of binaries are complicated by incomplete or missing observational data and by a number of observational selection effects. Visual binaries are the most common type of observed binary stars, with the number of pairs exceeding 130 000. The most complete list of presently known visual binary stars was compiled by cross-matching objects and combining data of the three largest catalogues of visual binaries. This list was supplemented by the data on parallaxes, multicolor photometry, and spectral characteristics taken from other catalogues. This allowed us to compensate partly for the lack of observational data for these objects. The combined data allowed us to check the validity of observational values and to investigate statistics of the orbital and physical parameters of visual binaries. Corrections for incompleteness of observational data are discussed. The datasets obtained, together with modern distributions of binary parameters, will be used to reconstruct the initial distributions and parameters of the function of star formation for binary systems.

  2. 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.

  3. Electron Ionization Cross Sections in the Distorted-Wave Approximation.

    DTIC Science & Technology

    1980-06-18

    solution T(rl, r2 ) of the Schr ~ dinger equation is not known. Moreover, it is difficult to satisfy condition (9) for effective charges Z and Z’ as... computing time . It is therefore suitable for a production of large number of data needed in the analysis and interpretation of hot plasmas in laboratory...goal was to develop an approximation based on the quantum-mechanical approach to the collision problem, simple enough so that it would be suitable

  4. Bowen-York-type initial data for binaries with neutron stars

    NASA Astrophysics Data System (ADS)

    Clark, Michael; Laguna, Pablo

    2016-09-01

    A new approach to construct initial data for binary systems with neutron star components is introduced. The approach is a generalization of the puncture initial data method for binary black holes based on Bowen-York solutions to the momentum constraint. As with binary black holes, the method allows setting orbital configurations with direct input from post-Newtonian approximations and involves solving only the Hamiltonian constraint. The effectiveness of the method is demonstrated with evolutions of double neutron star and black hole-neutron star binaries in quasicircular orbits.

  5. Probability Quantization for Multiplication-Free Binary Arithmetic Coding

    NASA Technical Reports Server (NTRS)

    Cheung, K. -M.

    1995-01-01

    A method has been developed to improve on Witten's binary arithmetic coding procedure of tracking a high value and a low value. The new method approximates the probability of the less probable symbol, which improves the worst-case coding efficiency.

  6. Wide- and contact-binary formation in substructured young stellar clusters

    NASA Astrophysics Data System (ADS)

    Dorval, J.; Boily, C. M.; Moraux, E.; Roos, O.

    2017-02-01

    We explore with collisional gravitational N-body models the evolution of binary stars in initially fragmented and globally subvirial clusters of stars. Binaries are inserted in the (initially) clumpy configurations so as to match the observed distributions of the field-binary-stars' semimajor axes a and binary fraction versus primary mass. The dissolution rate of wide binaries is very high at the start of the simulations, and is much reduced once the clumps are eroded by the global infall. The transition between the two regimes is sharper as the number of stars N is increased, from N = 1.5 k up to 80 k. The fraction of dissolved binary stars increases only mildly with N, from ≈15 per cent to ≈25 per cent for the same range in N. We repeated the calculation for two initial system mean number densities of 6 per pc3 (low) and 400 per pc3 (high). We found that the longer free-fall time of the low-density runs allows for prolonged binary-binary interactions inside clumps and the formation of very tight (a ≈ 0.01 au) binaries by exchange collisions. This is an indication that the statistics of such compact binaries bear a direct link to their environment at birth. We also explore the formation of wide (a ≳ 5 × 104 au) binaries and find a low (≈0.01 per cent) fraction mildly bound to the central star cluster. The high-precision astrometric mission Gaia could identify them as outflowing shells or streams.

  7. Conservative Analytical Collision Probability for Design of Orbital Formations

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell

    2004-01-01

    The literature offers a number of approximations for analytically and/or efficiently computing the probability of collision between two space objects. However, only one of these techniques is a completely analytical approximation that is suitable for use in the preliminary design phase, when it is more important to quickly analyze a large segment of the trade space than it is to precisely compute collision probabilities. Unfortunately, among the types of formations that one might consider, some combine a range of conditions for which this analytical method is less suitable. This work proposes a simple, conservative approximation that produces reasonable upper bounds on the collision probability in such conditions. Although its estimates are much too conservative under other conditions, such conditions are typically well suited for use of the existing method.

  8. Conservative Analytical Collision Probabilities for Orbital Formation Flying

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell

    2004-01-01

    The literature offers a number of approximations for analytically and/or efficiently computing the probability of collision between two space objects. However, only one of these techniques is a completely analytical approximation that is suitable for use in the preliminary design phase, when it is more important to quickly analyze a large segment of the trade space than it is to precisely compute collision probabilities. Unfortunately, among the types of formations that one might consider, some combine a range of conditions for which this analytical method is less suitable. This work proposes a simple, conservative approximation that produces reasonable upper bounds on the collision probability in such conditions. Although its estimates are much too conservative under other conditions, such conditions are typically well suited for use of the existing method.

  9. Pycnonuclear reaction rates for binary ionic mixtures

    NASA Technical Reports Server (NTRS)

    Ichimaru, S.; Ogata, S.; Van Horn, H. M.

    1992-01-01

    Through a combination of compositional scaling arguments and examinations of Monte Carlo simulation results for the interparticle separations in binary-ionic mixture (BIM) solids, we have derived parameterized expressions for the BIM pycnonuclear rates as generalizations of those in one-component solids obtained previously by Salpeter and Van Horn and by Ogata et al. We have thereby discovered a catalyzing effect of the heavier elements, which enhances the rates of reactions among the lighter elements when the charge ratio exceeds a critical value of approximately 2.3.

  10. Elliptic waveforms for inspiralling compact binaries

    NASA Astrophysics Data System (ADS)

    Mikóczi, Balázs

    2010-03-01

    The inspiral of supermassive black hole binary systems with high orbital eccentricity are the most promising sources for the gravitational wave observatories. The importance of elliptic gravitational waveforms in various physical scenarios has been emphasized by several authors (Wahlquist 1987, Moreno-Garrido, Buitrago and Mediavilla 1994, Martel and Poisson 1999). Taking into account the eccentricity of the orbit in the total waveform improves the parameter estimation for these sources, as it is shown by the construction and analyzation of the Fisher information matrix. In our work we use the Fourier-Bessel analysis of the Kepler motion and the stationary phase approximation of time-depend waveforms.

  11. Binary optics: Trends and limitations

    NASA Astrophysics Data System (ADS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-08-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  12. Binary optics: Trends and limitations

    NASA Technical Reports Server (NTRS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-01-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  13. Shear viscosity for a heated granular binary mixture at low density.

    PubMed

    Montanero, José María; Garzó, Vicente

    2003-02-01

    The shear viscosity for a heated granular binary mixture of smooth hard spheres at low density is analyzed. The mixture is heated by the action of an external driving force (Gaussian thermostat) that exactly compensates for cooling effects associated with the dissipation of collisions. The study is made from the Boltzmann kinetic theory, which is solved by using two complementary approaches. First, a normal solution of the Boltzmann equation via the Chapman-Enskog method is obtained up to first order in the spatial gradients. The mass, heat, and momentum fluxes are determined and the corresponding transport coefficients identified. As in the free cooling case [V. Garzó and J. W. Dufty, Phys. Fluids 14, 1476 (2002)], practical evaluation requires a Sonine polynomial approximation, and here it is mainly illustrated in the case of the shear viscosity. Second, to check the accuracy of the Chapman-Enskog results, the Boltzmann equation is numerically solved by means of the direct simulation Monte Carlo method. The simulation is performed for a system under uniform shear flow, using the Gaussian thermostat to control inelastic cooling. The comparison shows an excellent agreement between theory and simulation over a wide range of values of the restitution coefficients and the parameters of the mixture (masses, concentrations, and sizes).

  14. Initial results of a full kinetic simulation of RF H{sup −} source including Coulomb collision process

    SciTech Connect

    Mochizuki, S.; Shibata, T.; Nishida, K.; Hatayama, A.; Mattei, S.; Lettry, J.

    2015-04-08

    In order to evaluate Electron Energy Distribution Function (EEDF) more correctly for radio frequency inductively coupled plasma (RF-ICP) in hydrogen negative ion sources, the Electromagnetic Particle-In-Cell (EM-PIC) simulation code has been improved by taking into account electron-electron Coulomb collision. Binary collision model is employed to model Coulomb collision process and we have successfully modeled it. The preliminary calculation including Coulomb collision has been done and it is shown that Coulomb collision doesn’t have significant effects under the condition: electron density n{sub e} ∼ 10{sup 18} m{sup −3} and high gas pressure p{sub H{sub 2}} = 3 Pa, while it is necessary to include Coulomb collision under high electron density and low gas pressure conditions.

  15. Binary module test. Final report

    SciTech Connect

    Schilling, J.R.; Colley, T.C.; Pundyk, J.

    1980-12-01

    The objective of this project was to design and test a binary loop module representative of and scaleable to commercial size units. The design was based on state-of-the-art heat exchanger technology, and the purpose of the tests was to confirm performance of a supercritical boiling cycle using isobutane and a mixture of isobutane and isopentane as the secondary working fluid. The module was designed as one percent of a 50 MW unit. It was installed at Magma Power's East Mesa geothermal field and tested over a period of approximately 4 months. Most of the test runs were with isobutane but some data were collected for hydrocarbon mixtures. The results of the field tests are reported. In general these results indicate reasonably good heat balances and agreement with overall heat transfer coefficients calculated by current stream analysis methods and available fluid property data; however, measured pressure drops across the heat exchangers were 20 percent higher than estimated. System operation was stable under all conditions tested.

  16. COLLISIONAL EVOLUTION OF ULTRA-WIDE TRANS-NEPTUNIAN BINARIES

    SciTech Connect

    Parker, Alex H.; Kavelaars, J. J.

    2012-01-10

    The widely separated, near-equal mass binaries hosted by the cold classical Kuiper Belt are delicately bound and subject to disruption by many perturbing processes. We use analytical arguments and numerical simulations to determine their collisional lifetimes given various impactor size distributions and include the effects of mass loss and multiple impacts over the lifetime of each system. These collisional lifetimes constrain the population of small (R {approx}> 1 km) objects currently residing in the Kuiper Belt and confirm that the size distribution slope at small size cannot be excessively steep-likely q {approx}< 3.5. We track mutual semimajor axis, inclination, and eccentricity evolution through our simulations and show that it is unlikely that the wide binary population represents an evolved tail of the primordially tight binary population. We find that if the wide binaries are a collisionally eroded population, their primordial mutual orbit planes must have preferred to lie in the plane of the solar system. Finally, we find that current limits on the size distribution at small radii remain high enough that the prospect of detecting dust-producing collisions in real time in the Kuiper Belt with future optical surveys is feasible.

  17. Evolution of Close Binary Systems

    SciTech Connect

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  18. Multiwavelength Studies of gamma-ray Binaries

    NASA Astrophysics Data System (ADS)

    Aragona, Christina

    2011-01-01

    High mass X-ray binaries (HMXBs) consist of an O or B star orbited by either a neutron star or a black hole. Of the 114 known Galactic HMXBs, a handful of these objects, dubbed gamma-ray binaries, have been observed to produce MeV-TeV emission. The very high energy emission can be produced either by accretion from the stellar wind onto a black hole or a collision between the stellar wind and a relativistic pulsar wind. Both these scenarios make gamma-ray binaries valuable nearby systems for studying the physics of shocks and jets. Currently, the nature of the compact object and the high energy production mechanism is unknown or unconfirmed in over half of these systems. My goal for this dissertation is to constrain the parameters describing two of these systems: LS 5039 and HD 259440. LS 5039 exhibits gamma-ray emission modulated with its orbital period. The system consists of an ON6.5V((f)) star and an unidentified compact companion. Using optical spectra from the CTIO 1.5m telescope, we found LS 5039 to have an orbital period of 3.90608 d and an eccentricity of 0.337. Spectra of the Halpha line observed with SOAR indicate a mass loss rate of ˜ 1.9x10 -8 M yr-1. Observations taken with ATCA at 13 cm, 6 cm, and 3 cm indicate radio fluxes between 10--40 mJy. The measurements show variability with time, indicating a source other than thermal emission from the stellar wind. HD 259440 is a B0pe star that was proposed as the optical counterpart to the gamma-ray source HESS J0632+057. Using optical spectra from the KPNO CF, KPNO 2.1m, and OHP telescopes, we find a best fit stellar effective temperature of 27500--30000 K, a log surface gravity of 3.75--4.0, a mass of 13.2--19.0 Msolar, and a radius of 6.0--9.6 Rsolar. By fitting the spectral energy distribution, we find a distance between 1.1--1.7 kpc. We do not detect any significant radial velocity shifts in our data, ruling out orbital periods shorter than one month. If HD 259440 is a binary, it is likely a long

  19. Black-hole binary evolutions with the LEAN code

    NASA Astrophysics Data System (ADS)

    Sperhake, Ulrich

    2007-05-01

    Numerical simulations of black-hole binaries, obtained with the Lean code, are presented. The code is demonstrated to produce state-of-the-art evolutions of inspiralling and merging black holes with convergent waveforms. We further compare results from head-on collisions of Brill-Lindquist and Kerr-Schild data to study the dependency of the waveforms on the choice of initial data type. In this comparison we find good qualitative agreement between the results of both data types, but observe a systematic discrepancy of about 10% in the wave amplitudes. Several attempts to explain the observed discrepancy are discussed.

  20. 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.

  1. Uniform Approximation of a Maxwellian Thermostat by Finite Reservoirs

    NASA Astrophysics Data System (ADS)

    Bonetto, F.; Loss, M.; Tossounian, H.; Vaidyanathan, R.

    2017-04-01

    We study a system of M particles in contact with a large but finite reservoir of {N ≫ M} particles within the framework of the Kac master equation modeling random collisions. The reservoir is initially in equilibrium at temperature {T=β^{-1}}. We show that for large N, this evolution can be approximated by an effective equation in which the reservoir is described by a Maxwellian thermostat at temperature T. This approximation is proven for a suitable {L^2} norm as well as for the Gabetta-Toscani-Wennberg (GTW) distance and is uniform in time.

  2. BINARY STORAGE ELEMENT

    DOEpatents

    Chu, J.C.

    1958-06-10

    A binary storage device is described comprising a toggle provided with associsted improved driver circuits adapted to produce reliable action of the toggle during clearing of the toggle to one of its two states. or transferring information into and out of the toggle. The invention resides in the development of a self-regulating driver circuit to minimize the fluctuation of the driving voltages for the toggle. The disclosed driver circuit produces two pulses in response to an input pulse: a first or ''clear'' pulse beginning nt substantially the same time but endlrg slightly sooner than the second or ''transfer'' output pulse.

  3. Low autocorrelation binary sequences

    NASA Astrophysics Data System (ADS)

    Packebusch, Tom; Mertens, Stephan

    2016-04-01

    Binary sequences with minimal autocorrelations have applications in communication engineering, mathematics and computer science. In statistical physics they appear as groundstates of the Bernasconi model. Finding these sequences is a notoriously hard problem, that so far can be solved only by exhaustive search. We review recent algorithms and present a new algorithm that finds optimal sequences of length N in time O(N {1.73}N). We computed all optimal sequences for N≤slant 66 and all optimal skewsymmetric sequences for N≤slant 119.

  4. Some (Apparently) Very Wide Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Stephens, Robert D.

    2016-10-01

    We present lightcurves for some of the approximately one dozen asteroids that appear to be very widely-separated binaries. Jacobsen et al. (2014, ApJ 780) attribute their formation to a somewhat complex series of events involving BYORP.The lightcurves consist of two components: Period 1 (P1) is very long, P1 = 50-600 h, with amplitudes of A1 = 0.23-1.0 mag. The second period and amplitudes are similar to the primaries of close binary systems, i.e., P2 = 2.2-3.6 h, A2 ~ 0.10 mag. Two candidates have secondary periods in the range of 5-7 hours. The most exceptional example is (19204) Joshuatree, which has values of P1 = 480 h, A1 = 0.25 mag and P2 = 21.25 h, A2 = 0.08 mag. Based on Jacobson et al. (2014, ApJ 780) and Pravec et al. (2016, Icarus 267), we suggest that P1 represents the primary (larger) body of the system and P2 represents the spin rate of the satellite.Supporting this supposition is that the large amplitude (A1) must be from the larger body, otherwise the dilution of amplitude would require the smaller body to be unreasonably elongate. The limiting size ratio for binaries is around 0.6 (see Pravec et al. 2010, Nature 466, Fig. 1), or a magnitude difference of about 1.0. For a secondary 1.0 mag fainter than the primary to produce a combined lightcurve amplitude of ~0.4 mag would require that the secondary undiluted amplitude to be several magnitudes (near-infinite elongation) and also a near equatorial aspect. This is not likely.Given the lack of mutual events, these can be considered to be only possible binaries. Since the orbital period is probably very long, it seems extremely unlikely that mutual events will ever be seen.The changing landscape of binary asteroid discoveries and theories calls for something beyond descriptive terms such as "suspicious", "possible", "likely", and "confirmed" in order to allow more accurate statistical studies. To this end, we are introducing a new "B" rating in the asteroid lightcurve database (Warner et al., 2009

  5. The binary Kuiper-belt object 1998 WW31.

    PubMed

    Veillet, Christian; Parker, Joel Wm; Griffin, Ian; Marsden, Brian; Doressoundiram, Alain; Buie, Marc; Tholen, David J; Connelley, Michael; Holman, Matthew J

    2002-04-18

    The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan asteroids have subsequently been discovered. The Kuiper belt-the region of space extending from Neptune (at 30 astronomical units) to well over 100 AU and believed to be the source of new short-period comets-has become a fascinating new window onto the formation of our Solar System since the first member object, not counting Pluto, was discovered in 1992 (ref. 13). Here we report that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e approximately 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in the Kuiper belt. Assuming a density in the range of 1 to 2 g cm-3, the albedo of the binary components is between 0.05 and 0.08, close to the value of 0.04 generally assumed for Kuiper-belt objects.

  6. Multi-Messenger Astronomy: White Dwarf Binaries, LISA and GAIA

    NASA Astrophysics Data System (ADS)

    Bueno, Michael; Breivik, Katelyn; Larson, Shane L.

    2017-01-01

    The discovery of gravitational waves has ushered in a new era in astronomy. The low-frequency band covered by the future LISA detector provides unprecedented opportunities for multi-messenger astronomy. With the Global Astrometric Interferometer for Astrophysics (GAIA) mission, we expect to discover about 1,000 eclipsing binary systems composed of a WD and a main sequence star - a sizeable increase from the approximately 34 currently known binaries of this type. In advance of the first GAIA data release and the launch of LISA within the next decade, we used the Binary Stellar Evolution (BSE) code simulate the evolution of White Dwarf Binaries (WDB) in a fixed galaxy population of about 196,000 sources. Our goal is to assess the detectability of a WDB by LISA and GAIA using the parameters from our population synthesis, we calculate GW strength h, and apparent GAIA magnitude G. We can then use a scale factor to make a prediction of how many multi- messenger sources we expect to be detectable by both LISA and GAIA in a galaxy the size of the Milky Way. We create binaries 10 times to ensure randomness in distance assignment and average our results. We then determined whether or not astronomical chirp is the difference between the total chirp and the GW chirp. With Astronomical chirp and simulations of mass transfer and tides, we can gather more information about the internal astrophysics of stars in ultra-compact binary systems.

  7. DALI: Derivative Approximation for LIkelihoods

    NASA Astrophysics Data System (ADS)

    Sellentin, Elena

    2015-07-01

    DALI (Derivative Approximation for LIkelihoods) is a fast approximation of non-Gaussian likelihoods. It extends the Fisher Matrix in a straightforward way and allows for a wider range of posterior shapes. The code is written in C/C++.

  8. First-principles binary diffusion coefficients for H, H{sub 2}, and four normal alkanes + N{sub 2}

    SciTech Connect

    Jasper, Ahren W. Kamarchik, Eugene; Miller, James A.; Klippenstein, Stephen J.

    2014-09-28

    Collision integrals related to binary (dilute gas) diffusion are calculated classically for six species colliding with N{sub 2}. The most detailed calculations make no assumptions regarding the complexity of the potential energy surface, and the resulting classical collision integrals are in excellent agreement with previous semiclassical results for H + N{sub 2} and H{sub 2} + N{sub 2} and with recent experimental results for C{sub n}H{sub 2n+2} + N{sub 2}, n = 2–4. The detailed classical results are used to test the accuracy of three simplifying assumptions typically made when calculating collision integrals: (1) approximating the intermolecular potential as isotropic, (2) neglecting the internal structure of the colliders (i.e., neglecting inelasticity), and (3) employing unphysical R{sup −12} repulsive interactions. The effect of anisotropy is found to be negligible for H + N{sub 2} and H{sub 2} + N{sub 2} (in agreement with previous quantum mechanical and semiclassical results for systems involving atomic and diatomic species) but is more significant for larger species at low temperatures. For example, the neglect of anisotropy decreases the diffusion coefficient for butane + N{sub 2} by 15% at 300 K. The neglect of inelasticity, in contrast, introduces only very small errors. Approximating the repulsive wall as an unphysical R{sup −12} interaction is a significant source of error at all temperatures for the weakly interacting systems H + N{sub 2} and H{sub 2} + N{sub 2}, with errors as large as 40%. For the normal alkanes in N{sub 2}, which feature stronger interactions, the 12/6 Lennard–Jones approximation is found to be accurate, particularly at temperatures above ∼700 K where it predicts the full-dimensional result to within 5% (although with somewhat different temperature dependence). Overall, the typical practical approach of assuming isotropic 12/6 Lennard–Jones interactions is confirmed to be suitable for combustion applications except for

  9. Taylor Approximations and Definite Integrals

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.

    2007-01-01

    We investigate the possibility of approximating the value of a definite integral by approximating the integrand rather than using numerical methods to approximate the value of the definite integral. Particular cases considered include examples where the integral is improper, such as an elliptic integral. (Contains 4 tables and 2 figures.)

  10. 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.

  11. Vacancy-rearrangement theory in the first Magnus approximation

    SciTech Connect

    Becker, R.L.

    1984-01-01

    In the present paper we employ the first Magnus approximation (M1A), a unitarized Born approximation, in semiclassical collision theory. We have found previously that the M1A gives a substantial improvement over the first Born approximation (B1A) and can give a good approximation to a full coupled channels calculation of the mean L-shell vacancy probability per electron, p/sub L/, when the L-vacancies are accompanied by a K-shell vacancy (p/sub L/ is obtained experimentally from measurements of K/sub ..cap alpha../-satellite intensities). For sufficiently strong projectile-electron interactions (sufficiently large Z/sub p/ or small v) the M1A ceases to reproduce the coupled channels results, but it is accurate over a much wider range of Z/sub p/ and v than the B1A. 27 references.

  12. Time-step Considerations in Particle Simulation Algorithms for Coulomb Collisions in Plasmas

    SciTech Connect

    Cohen, B I; Dimits, A; Friedman, A; Caflisch, R

    2009-10-29

    The accuracy of first-order Euler and higher-order time-integration algorithms for grid-based Langevin equations collision models in a specific relaxation test problem is assessed. We show that statistical noise errors can overshadow time-step errors and argue that statistical noise errors can be conflated with time-step effects. Using a higher-order integration scheme may not achieve any benefit in accuracy for examples of practical interest. We also investigate the collisional relaxation of an initial electron-ion relative drift and the collisional relaxation to a resistive steady-state in which a quasi-steady current is driven by a constant applied electric field, as functions of the time step used to resolve the collision processes using binary and grid-based, test-particle Langevin equations models. We compare results from two grid-based Langevin equations collision algorithms to results from a binary collision algorithm for modeling electronion collisions. Some guidance is provided regarding how large a time step can be used compared to the inverse of the characteristic collision frequency for specific relaxation processes.

  13. Interparticle collision mechanism in turbulence.

    PubMed

    Choi, Jung-Il; Park, Yongnam; Kwon, Ohjoon; Lee, Changhoon

    2016-01-01

    Direct numerical simulations of particle-laden homogeneous isotropic turbulence are performed to investigate interparticle collisions in a wide range of Stokes numbers. Dynamics of the particles are described by Stokes drag including particle-particle interactions via hard-sphere collisions, while fluid turbulence is solved using a pseudospectral method. Particular emphasis is placed on interparticle-collision-based conditional statistics of rotation and dissipation rates of the fluid experienced by heavy particles, which provide essential information on the collision process. We also investigate the collision statistics of collision time interval and angle. Based on a Lamb vortex model for a vortex structure, we claim that collision events occur in the edge region for vortical structures in the intermediate-Stokes-number regime, suggesting that the sling effect enhances collision as well as clustering.

  14. J/psi production at high transverse momenta in p+p and Cu+Cu collisions at sqrt sNN = 200 GeV

    SciTech Connect

    STAR Collaboration; Abelev, B. I.

    2009-10-27

    The STAR collaboration at RHIC presents measurements of J/{psi} {yields} e{sup +}e{sup -} at mid-rapidity and high transverse momentum (p{sub T} > 5 GeV/c) in p+p and central Cu+Cu collisions at {radical}sNN = 200 GeV. The inclusive J/{psi} production cross section for Cu+Cu collisions is found to be consistent at high p{sub T} with the binary collision-scaled cross section for p+p collisions, in contrast to previous measurements at lower p{sub T}, where a suppression of J/{psi} production is observed relative to the expectation from binary scaling. Azimuthal correlations of J/{psi} with charged hadrons in p+p collisions provide an estimate of the contribution of B-meson decays to J/{psi} production of 13% {+-} 5%.

  15. 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.

  16. 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.

  17. Novel ID-based anti-collision approach for RFID

    NASA Astrophysics Data System (ADS)

    Zhang, De-Gan; Li, Wen-Bin

    2016-09-01

    Novel correlation ID-based (CID) anti-collision approach for RFID under the banner of the Internet of Things (IOT) has been presented in this paper. The key insights are as follows: according to the deterministic algorithms which are based on the binary search tree, we propose a method to increase the association between tags so that tags can initiatively send their own ID under certain trigger conditions, at the same time, we present a multi-tree search method for querying. When the number of tags is small, by replacing the actual ID with the temporary ID, it can greatly reduce the number of times that the reader reads and writes to tag's ID. Active tags send data to the reader by the way of modulation binary pulses. When applying this method to the uncertain ALOHA algorithms, the reader can determine the locations of the empty slots according to the position of the binary pulse, so it can avoid the decrease in efficiency which is caused by reading empty slots when reading slots. Theory and experiment show that this method can greatly improve the recognition efficiency of the system when applied to either the search tree or the ALOHA anti-collision algorithms.

  18. Relativistic Binaries in Globular Clusters.

    PubMed

    Benacquista, Matthew J; Downing, Jonathan M B

    2013-01-01

    Galactic globular clusters are old, dense star systems typically containing 10(4)-10(6) stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of tight binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker-Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.

  19. Multilevel Models for Binary Data

    ERIC Educational Resources Information Center

    Powers, Daniel A.

    2012-01-01

    The methods and models for categorical data analysis cover considerable ground, ranging from regression-type models for binary and binomial data, count data, to ordered and unordered polytomous variables, as well as regression models that mix qualitative and continuous data. This article focuses on methods for binary or binomial data, which are…

  20. Treatment of Ion-Atom Collisions Using a Partial-Wave Expansion of the Projectile Wavefunction

    ERIC Educational Resources Information Center

    Wong, T. G.; Foster, M.; Colgan, J.; Madison, D. H.

    2009-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge…

  1. Formation of Kuiper-belt binaries by dynamical friction and three-body encounters.

    PubMed

    Goldreich, Peter; Lithwick, Yoram; Sari, Re'em

    2002-12-12

    The Kuiper belt is a disk of icy bodies that orbit the Sun beyond Neptune; the largest known members are Pluto and its companion Charon. A few per cent of Kuiper-belt bodies have recently been found to be binaries with wide separations and mass ratios of the order of unity. Collisions were too infrequent to account for the observed number of binaries, implying that these binaries formed through collisionless interactions mediated by gravity. These interactions are likely to have been most effective during the period of runaway accretion, early in the Solar System's history. Here we show that a transient binary forms when two large bodies penetrate one another's Hill sphere (the region where their mutual forces are larger than the tidal force of the Sun). The loss of energy needed to stabilize the binary orbit can then occur either through dynamical friction from surrounding small bodies, or through the gravitational scattering of a third large body. Our estimates slightly favour the former mechanism. We predict that five per cent of Kuiper-belt objects are binaries with apparent separations greater than 0.2 arcsec, and that most are in tighter binaries or systems of higher multiplicity.

  2. Planning 3-D collision-free paths using spheres

    NASA Technical Reports Server (NTRS)

    Bonner, Susan; Kelley, Robert B.

    1989-01-01

    A scheme for the representation of objects, the Successive Spherical Approximation (SSA), facilitates the rapid planning of collision-free paths in a 3-D, dynamic environment. The hierarchical nature of the SSA allows collision-free paths to be determined efficiently while still providing for the exact representation of dynamic objects. The concept of a freespace cell is introduced to allow human 3-D conceptual knowledge to be used in facilitating satisfying choices for paths. Collisions can be detected at a rate better than 1 second per environment object per path. This speed enables the path planning process to apply a hierarchy of rules to create a heuristically satisfying collision-free path.

  3. Signature Visualization of Software Binaries

    SciTech Connect

    Panas, T

    2008-07-01

    In this paper we present work on the visualization of software binaries. In particular, we utilize ROSE, an open source compiler infrastructure, to pre-process software binaries, and we apply a landscape metaphor to visualize the signature of each binary (malware). We define the signature of a binary as a metric-based layout of the functions contained in the binary. In our initial experiment, we visualize the signatures of a series of computer worms that all originate from the same line. These visualizations are useful for a number of reasons. First, the images reveal how the archetype has evolved over a series of versions of one worm. Second, one can see the distinct changes between version. This allows the viewer to form conclusions about the development cycle of a particular worm.

  4. 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

  5. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    SciTech Connect

    Sajadian, Sedighe

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth due to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.

  6. Evolution of Small Binary Asteroids with the Binary YORP Effect

    NASA Astrophysics Data System (ADS)

    Frouard, Julien

    2013-05-01

    Abstract (2,250 Maximum Characters): Small, Near-Earth binaries are believed to be created following the fission of an asteroid spun up by the YORP effect. It is then believed that the YORP effect acting on the secondary (Binary YORP) increases or decreases the binary mutual distance on 10^5 yr timescales. How long this mechanism can apply is not yet fully understood. We investigate the binary orbital and rotational dynamics by using non-averaged, direct numerical simulations, taking into account the relative motion of two ellipsoids (primary and secondary) and the solar perturbation. We add the YORP force and torque on the orbital and rotational motion of the secondary. As a check of our code we obtain a ~ 7.2 cm/yr drift in semi-major axis for 1999 KW4 beta, consistent with the values obtained with former analytical studies. The synchronous rotation of the secondary is required for the Binary YORP to be effective. We investigate the synchronous lock of the secondary in function of different parameters ; mutual distance, shape of the secondary, and heliocentric orbit. For example we show that the secondary of 1999 KW4 can be synchronous only up to 7 Rp (primary radius), where the resonance becomes completely chaotic even for very small eccentricities. We use Gaussian Random Spheres to obtain various secondary shapes, and check the evolution of the binaries with the Binary YORP effect.

  7. Binary rototranslational hyper-Rayleigh spectra of H(2)-He gas mixture.

    PubMed

    Godet, J-L; Bancewicz, T; Głaz, W; Maroulis, G; Haskopoulos, A

    2009-11-28

    The collision-induced rototranslational hyper-Rayleigh spectra of gaseous H(2)-He mixture are computed and discussed in the binary regime. As the input data we use our ab initio computed H(2)-He collision-induced first dipole hyperpolarizability tensor Deltabeta(R). Both the vector and the septor part of the H(2)-He hyper-Rayleigh spectra are evaluated at room temperature (T=295 K). The spectra are calculated assuming the full quantum computations based on the Schrödinger equation of the relative translational motion in the isotropic H(2)-He potential as well as using semiclassical methods.

  8. VLTI-AMBER Velocity-Resolved Aperture-Synthesis Imaging of Eta Carinae with a Spectral Resolution of 12 000: Studies of the Primary Star Wind and Innermost Wind-Wind Collision Zone

    NASA Technical Reports Server (NTRS)

    Weigelt, G.; Hofmann, K.-H.; Schertl, D.; Clementel, N.; Corcoran, M. F.; Damineli, A.; de Wit, W.-J.; Grellmann, R.; Groh, J.; Guieu, S.; Gull, T.; Heininger, M.; Hillier, D. J.; Hummel, C. A.; Kraus, S.; Madura, T.; Mehner, A.; Merand, A.; Millour, F.; Moffat, A. F. J.; Ohnaka, K.; Patru, F.; Petrov, R. G.; Rengaswamy, S.; Richardson, N. D.; Rivinius, T.; Schoeller, M.; Teodoro, M.; Wittkowski, M.

    2016-01-01

    The mass loss from massive stars is not understood well. Eta Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Aims. We want to investigate the structure and kinematics of Car's primary star wind and wind-wind collision zone with a high spatial resolution of approx.6 mas (approx.14 au) and high spectral resolution of R = 12 000. Methods. Observations of Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision. Results. We present velocity-resolved aperture-synthesis images reconstructed in more than 100 di erent spectral channels distributed across the Br(gamma) 2.166 micron emission line. The intensity distribution of the images strongly depends on wavelength. At wavelengths corresponding to radial velocities of approximately -140 to -376 km/s measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of -277 km/s, the position angle of the symmetry axis of the fan is 126. The fan-shaped structure extends approximately 8.0 mas (approx.18:8 au) to the southeast and 5.8 mas (approx.13:6 au) to the northwest, measured along the symmetry axis at the 16% intensity contour. The shape of the intensity distributions suggests that the obtained images are the first direct images of the innermost wind-wind collision zone. Therefore, the observations provide velocity-dependent image structures that can be used to test three

  9. VLTI-AMBER velocity-resolved aperture-synthesis imaging of η Carinae with a spectral resolution of 12 000. Studies of the primary star wind and innermost wind-wind collision zone

    NASA Astrophysics Data System (ADS)

    Weigelt, G.; Hofmann, K.-H.; Schertl, D.; Clementel, N.; Corcoran, M. F.; Damineli, A.; de Wit, W.-J.; Grellmann, R.; Groh, J.; Guieu, S.; Gull, T.; Heininger, M.; Hillier, D. J.; Hummel, C. A.; Kraus, S.; Madura, T.; Mehner, A.; Mérand, A.; Millour, F.; Moffat, A. F. J.; Ohnaka, K.; Patru, F.; Petrov, R. G.; Rengaswamy, S.; Richardson, N. D.; Rivinius, T.; Schöller, M.; Teodoro, M.; Wittkowski, M.

    2016-10-01

    Context. The mass loss from massive stars is not understood well. η Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Aims: We want to investigate the structure and kinematics of η Car's primary star wind and wind-wind collision zone with a high spatial resolution of ~6 mas (~14 au) and high spectral resolution of R = 12 000. Methods: Observations of η Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision. Results: We present velocity-resolved aperture-synthesis images reconstructed in more than 100 different spectral channels distributed across the Brγ 2.166 μm emission line. The intensity distribution of the images strongly depends on wavelength. At wavelengths corresponding to radial velocities of approximately -140 to - 376 km s-1 measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of - 277 km s-1, the position angle of the symmetry axis of the fan is ~126°. The fan-shaped structure extends approximately 8.0 mas (~18.8 au) to the southeast and 5.8 mas (~13.6 au) to the northwest, measured along the symmetry axis at the 16% intensity contour. The shape of the intensity distributions suggests that the obtained images are the first direct images of the innermost wind-wind collision zone. Therefore, the observations provide velocity-dependent image structures that can be used to test three

  10. 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.

  11. 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.

  12. Effective potential theory for diffusion in binary ionic mixtures.

    PubMed

    Shaffer, Nathaniel R; Baalrud, Scott D; Daligault, Jérôme

    2017-01-01

    Self-diffusion and interdiffusion coefficients of binary ionic mixtures are evaluated using the effective potential theory (EPT), and the predictions are compared with the results of molecular dynamics simulations. We find that EPT agrees with molecular dynamics from weak coupling well into the strong-coupling regime, which is a similar range of coupling strengths as previously observed in comparisons with the one-component plasma. Within this range, typical relative errors of approximately 20% and worst-case relative errors of approximately 40% are observed. We also examine the Darken model, which approximates the interdiffusion coefficients based on the self-diffusion coefficients.

  13. Effective potential theory for diffusion in binary ionic mixtures

    NASA Astrophysics Data System (ADS)

    Shaffer, Nathaniel R.; Baalrud, Scott D.; Daligault, Jérôme

    2017-01-01

    Self-diffusion and interdiffusion coefficients of binary ionic mixtures are evaluated using the effective potential theory (EPT), and the predictions are compared with the results of molecular dynamics simulations. We find that EPT agrees with molecular dynamics from weak coupling well into the strong-coupling regime, which is a similar range of coupling strengths as previously observed in comparisons with the one-component plasma. Within this range, typical relative errors of approximately 20% and worst-case relative errors of approximately 40% are observed. We also examine the Darken model, which approximates the interdiffusion coefficients based on the self-diffusion coefficients.

  14. Combining global and local approximations

    NASA Technical Reports Server (NTRS)

    Haftka, Raphael T.

    1991-01-01

    A method based on a linear approximation to a scaling factor, designated the 'global-local approximation' (GLA) method, is presented and shown capable of extending the range of usefulness of derivative-based approximations to a more refined model. The GLA approach refines the conventional scaling factor by means of a linearly varying, rather than constant, scaling factor. The capabilities of the method are demonstrated for a simple beam example with a crude and more refined FEM model.

  15. Combining global and local approximations

    SciTech Connect

    Haftka, R.T. )

    1991-09-01

    A method based on a linear approximation to a scaling factor, designated the 'global-local approximation' (GLA) method, is presented and shown capable of extending the range of usefulness of derivative-based approximations to a more refined model. The GLA approach refines the conventional scaling factor by means of a linearly varying, rather than constant, scaling factor. The capabilities of the method are demonstrated for a simple beam example with a crude and more refined FEM model. 6 refs.

  16. CHARACTERIZATION OF SEVEN ULTRA-WIDE TRANS-NEPTUNIAN BINARIES

    SciTech Connect

    Parker, Alex H.; Kavelaars, J. J.; Petit, Jean-Marc; Jones, Lynne; Gladman, Brett; Parker, Joel

    2011-12-10

    The low-inclination component of the Classical Kuiper Belt is host to a population of extremely widely separated binaries. These systems are similar to other trans-Neptunian binaries (TNBs) in that the primary and secondary components of each system are of roughly equal size. We have performed an astrometric monitoring campaign of a sample of seven wide-separation, long-period TNBs and present the first-ever well-characterized mutual orbits for each system. The sample contains the most eccentric (2006 CH{sub 69}, e{sub m} = 0.9) and the most widely separated, weakly bound (2001 QW{sub 322}, a/R{sub H} {approx_equal} 0.22) binary minor planets known, and also contains the system with lowest-measured mass of any TNB (2000 CF{sub 105}, M{sub sys} {approx_equal} 1.85 Multiplication-Sign 10{sup 17} kg). Four systems orbit in a prograde sense, and three in a retrograde sense. They have a different mutual inclination distribution compared to all other TNBs, preferring low mutual-inclination orbits. These systems have geometric r-band albedos in the range of 0.09-0.3, consistent with radiometric albedo estimates for larger solitary low-inclination Classical Kuiper Belt objects, and we limit the plausible distribution of albedos in this region of the Kuiper Belt. We find that gravitational collapse binary formation models produce an orbital distribution similar to that currently observed, which along with a confluence of other factors supports formation of the cold Classical Kuiper Belt in situ through relatively rapid gravitational collapse rather than slow hierarchical accretion. We show that these binary systems are sensitive to disruption via collisions, and their existence suggests that the size distribution of TNOs at small sizes remains relatively shallow.

  17. Phenomenological applications of rational approximants

    NASA Astrophysics Data System (ADS)

    Gonzàlez-Solís, Sergi; Masjuan, Pere

    2016-08-01

    We illustrate the powerfulness of Padé approximants (PAs) as a summation method and explore one of their extensions, the so-called quadratic approximant (QAs), to access both space- and (low-energy) time-like (TL) regions. As an introductory and pedagogical exercise, the function 1 zln(1 + z) is approximated by both kind of approximants. Then, PAs are applied to predict pseudoscalar meson Dalitz decays and to extract Vub from the semileptonic B → πℓνℓ decays. Finally, the π vector form factor in the TL region is explored using QAs.

  18. Automatic Aircraft Collision Avoidance System and Method

    NASA Technical Reports Server (NTRS)

    Skoog, Mark (Inventor); Hook, Loyd (Inventor); McWherter, Shaun (Inventor); Willhite, Jaimie (Inventor)

    2014-01-01

    The invention is a system and method of compressing a DTM to be used in an Auto-GCAS system using a semi-regular geometric compression algorithm. In general, the invention operates by first selecting the boundaries of the three dimensional map to be compressed and dividing the three dimensional map data into regular areas. Next, a type of free-edged, flat geometric surface is selected which will be used to approximate terrain data of the three dimensional map data. The flat geometric surface is used to approximate terrain data for each regular area. The approximations are checked to determine if they fall within selected tolerances. If the approximation for a specific regular area is within specified tolerance, the data is saved for that specific regular area. If the approximation for a specific area falls outside the specified tolerances, the regular area is divided and a flat geometric surface approximation is made for each of the divided areas. This process is recursively repeated until all of the regular areas are approximated by flat geometric surfaces. Finally, the compressed three dimensional map data is provided to the automatic ground collision system for an aircraft.

  19. Shock Reflection in a Binary Mixture of Noble Gases

    NASA Astrophysics Data System (ADS)

    Whitlock, S. T.; Baganoff, D.

    1996-11-01

    The standard implementation of Bird's Direct Simulation Monte Carlo (DSMC) method for the simulation of multiple-specie flows uses single-specie transport data as input to an ad hoc combining formula to define parameters used in binary collisions between non-like species. To ascertain the suitability of this approach, we focus on the details of translational nonequilibrium in the flow of a binary mixture of noble gases. Existing experimental results for the one-dimensional reflection of a shock wave in a mixture of helium (He) and xenon (Xe) yield a standard of comparison. The molecular weight and diameter of He:Xe are sufficiently disparate so that the relevant time scales of the reflection process are distinct. Simulations are performed on the Intel Paragon using an adaptation of the DSMC method suitable for the parallel computing environment. Using the best characterizations of noble gas intermolecular potentials that have been published to date, we are able to produce simulations of the reflection process which compare favorably with experiment over a range of Xe concentrations. Investigations of various combining rules to arrive at non-like specie collision parameters indicate that any reasonable combining rule works provided that the single-specie data is physically realistic.

  20. The orbital eccentricities of binary millisecond pulsars in globular clusters

    NASA Technical Reports Server (NTRS)

    Rasio, Frederic A.; Heggie, Douglas C.

    1995-01-01

    Low-mass binary millisecond pulsars (LMBPs) are born with very small orbital eccentricities, typically of order e(sub i) approximately 10(exp -6) to 10(exp -3). In globular clusters, however, higher eccentricities e(sub f) much greater than e(sub i) can be induced by dynamical interactions with passing stars. Here we show that the cross section for this process is much larger than previously estimated. This is becuse, even for initially circular binaries, the induced eccentricity e(sub f) for an encounter with pericenter separation r(sub p) beyond a few times the binary semimajor axis a declines only as a power law (e(sub f) varies as (r(sub p)/a)(exp -5/2), and not as an exponential. We find that all currently known LMBPs in clusters were probably affected by interactions, with their current eccentricities typically greater than at birth by an order of magnitude or more.

  1. Contamination of RR Lyrae stars from Binary Evolution Pulsators

    NASA Astrophysics Data System (ADS)

    Karczmarek, P.

    2015-09-01

    A Binary Evolution Pulsator (BEP) is a low-mass (0.26 M_⊙) member of a binary system, which pulsates as a result of a former mass transfer to its companion. The BEP mimics RR~Lyrae-type pulsations, but has completely different internal structure and evolution history. Although there is only one known BEP (OGLE-BLG-RRLYR-02792), it has been estimated that approximately 0.2% of objects classified as RR Lyrae stars can be undetected Binary Evolution Pulsators. In the present work, this contamination value is re-evaluated using the population synthesis method. The output falls inside a range of values dependent on tuning the parameters in the StarTrack code, and varies from 0.06% to 0.43%.

  2. BINARIES AMONG DEBRIS DISK STARS

    SciTech Connect

    Rodriguez, David R.; Zuckerman, B.

    2012-02-01

    We have gathered a sample of 112 main-sequence stars with known debris disks. We collected published information and performed adaptive optics observations at Lick Observatory to determine if these debris disks are associated with binary or multiple stars. We discovered a previously unknown M-star companion to HD 1051 at a projected separation of 628 AU. We found that 25% {+-} 4% of our debris disk systems are binary or triple star systems, substantially less than the expected {approx}50%. The period distribution for these suggests a relative lack of systems with 1-100 AU separations. Only a few systems have blackbody disk radii comparable to the binary/triple separation. Together, these two characteristics suggest that binaries with intermediate separations of 1-100 AU readily clear out their disks. We find that the fractional disk luminosity, as a proxy for disk mass, is generally lower for multiple systems than for single stars at any given age. Hence, for a binary to possess a disk (or form planets) it must either be a very widely separated binary with disk particles orbiting a single star or it must be a small separation binary with a circumbinary disk.

  3. A possible mechanism to explain the lack of binary asteroids among the Plutinos

    NASA Astrophysics Data System (ADS)

    Compère, A.; Farrelly, D.; Lemaître, A.; Hestroffer, D.

    2013-10-01

    Context. Binary asteroids are common in the solar system, including in the Kuiper belt. However, there seems to be a marked disparity between the binary populations in the classical part of the Kuiper belt and the part of the belt in the 3:2 resonance with Neptune - i.e., the region inhabited by the Plutinos. In particular, binary Plutinos are extremely rare. Aims: We study the impact of the 3:2 resonance on the formation of Kuiper belt binaries, according to the Nice model, in order to explain such phenomenon. Methods: Numerical simulations are performed within the 2 + 2 body approximation (Sun/Neptune + binary partners). The MEGNO chaos indicator is used to map out regular and chaotic regions of phase space. Residence times of test (binary) particles within the Hill sphere are compared inside and outside of the 3:2 resonance. The effect of increasing the heliocentric eccentricity of the centre of mass of the binary system is studied. This is done because mean-motion resonances between a planet and an asteroid usually have the effect of increasing the eccentricity of the asteroid. Results: The stable zones in the MEGNO maps are mainly disrupted in the resonant, eccentric case: the number of binary asteroids created in this case is significantly lower than outside the 3:2 resonance. Conclusions: In the 2 + 2 body approximation, the pumping of the eccentricity of the centre of mass of a potential binary destabilises the formation of binaries. This may be a factor in explaining the scarcity of binaries in the Plutino population.

  4. Transverse momentum dependence of inclusive primary charged-particle production in p-Pb collisions at

    NASA Astrophysics Data System (ADS)

    Abelev, B.; Adam, J.; Adamová, D.; Aggarwal, M. M.; Agnello, M.; Agostinelli, A.; Agrawal, N.; Ahammed, Z.; Ahmad, N.; Ahmed, I.; Ahn, S. U.; Ahn, S. A.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Baumann, C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Belmont, R.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Berger, M. E.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Böhmer, F. V.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Casula, E. A. R.; Catanescu, V.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortese, P.; Cortés Maldonado, I.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dainese, A.; Dang, R.; Danu, A.; Das, D.; Das, I.; Das, K.; Das, S.; Dash, A.; Dash, S.; De, S.; Delagrange, H.; Deloff, A.; Dénes, E.; D'Erasmo, G.; De Caro, A.; de Cataldo, G.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; de Rooij, R.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Di Bari, D.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dørheim, S.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Dutta Majumdar, A. K.; Hilden, T. E.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdal, H. A.; Eschweiler, D.; Espagnon, B.; Esposito, M.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Fasel, M.; Fehlker, D.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floratos, E.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Garishvili, I.; Gerhard, J.; Germain, M.; Gheata, A.; Gheata, M.; Ghidini, B.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Graczykowski, L. K.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Guilbaud, M.; Gulbrandsen, K.; Gulkanyan, H.; Gumbo, M.; Gunji, T.; Gupta, A.; Gupta, R.; Khan, K. H.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hippolyte, B.; Hladky, J.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Innocenti, G. M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Jachołkowski, A.; Jacobs, P. M.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kadyshevskiy, V.; Kalcher, S.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Khan, M. M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Konevskikh, A.; Kovalenko, V.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kramer, F.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kučera, V.; Kucheriaev, Y.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, J.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; La Pointe, S. L.; La Rocca, P.; Lea, R.; Leardini, L.; Lee, G. R.; Legrand, I.; Lehnert, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; Leoncino, M.; León Monzón, I.; Lévai, P.; Li, S.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Lohner, D.; Loizides, C.; Lopez, X.; López Torres, E.; Lu, X.-G.; Luettig, P.; Lunardon, M.; Luparello, G.; Ma, R.; Maevskaya, A.; Mager, M.; Mahapatra, D. P.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Marín, A.; Markert, C.; Marquard, M.; Martashvili, I.; Martin, N. A.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martin Blanco, J.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Meddi, F.; Menchaca-Rocha, A.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mlynarz, J.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira De Godoy, D. A.; Moretto, S.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Müller, H.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nicassio, M.; Niculescu, M.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Nilsen, B. S.; Noferini, F.; Nomokonov, P.; Nooren, G.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Okatan, A.; Olah, L.; Oleniacz, J.; Oliveira Da Silva, A. C.; Onderwaater, J.; Oppedisano, C.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Sahoo, P.; Pachmayer, Y.; Pachr, M.; Pagano, P.; Paić, G.; Painke, F.; Pajares, C.; Pal, S. K.; Palmeri, A.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Patalakha, D. I.; Paticchio, V.; Paul, B.; Pawlak, T.; Peitzmann, T.; Pereira Da Costa, H.; Pereira De Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Pesci, A.; Peskov, V.; Pestov, Y.; Petráček, V.; Petran, M.; Petris, M.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Pohjoisaho, E. H. O.; Polichtchouk, B.; Poljak, N.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Potukuchi, B.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Rauf, A. W.; Razazi, V.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reicher, M.; Reidt, F.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohni, S.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, R.; Sahu, P. K.; Saini, J.; Sakai, S.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Sánchez Rodríguez, F. J.; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Segato, G.; Seger, J. E.; Sekiguchi, Y.; Selyuzhenkov, I.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabetai, A.; Shabratova, G.; Shahoyan, R.; Shangaraev, A.; Sharma, N.; Sharma, S.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Skjerdal, K.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Stolpovskiy, M.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Susa, T.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tarazona Martinez, A.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terrevoli, C.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; Vande Vyvre, P.; Van Der Maarel, J.; Van Hoorne, J. W.; van Leeuwen, M.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vechernin, V.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wagner, V.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yang, S.; Yano, S.; Yasnopolskiy, S.; Yi, J.; Yin, Z.; Yoo, I.-K.; Yushmanov, I.; Zaccolo, V.; Zach, C.; Zaman, A.; Zampolli, C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, F.; Zhou, Y.; Zhuo, Zhou; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zoccarato, Y.; Zyzak, M.

    2014-09-01

    The transverse momentum ($p_{\\mathrm T}$) distribution of primary charged particles is measured at midrapidity in minimum-bias p-Pb collisions at $\\sqrt{s_{\\mathrm{NN}}}=5.02$ TeV with the ALICE detector at the LHC in the range $0.15binary collision scaling of particle production in pp collisions, leading to a nuclear modification factor consistent with unity for $p_{\\mathrm T}$ larger than 2 GeV/$c$, with a weak indication of a Cronin-like enhancement for $p_{\\rm T}$ around 4 GeV/$c$. The measurement is compared to theoretical calculations and to data in Pb-Pb collisions at $\\sqrt{s_{\\mathrm{NN}}}=2.76$ TeV.

  5. The coupled states approximation for scattering of two diatoms

    NASA Technical Reports Server (NTRS)

    Heil, T. G.; Kouri, D. J.; Green, S.

    1978-01-01

    The paper presents a detailed development of the coupled-states approximation for the general case of two colliding diatomic molecules. The high-energy limit of the exact Lippman-Schwinger equation is applied, and the analysis follows the Shimoni and Kouri (1977) treatment of atom-diatom collisions where the coupled rotor angular momentum and projection replace the single diatom angular momentum and projection. Parallels to the expression for the differential scattering amplitude, the opacity function, and the nondiagonality of the T matrix are reported. Symmetrized expressions and symmetrized coupled equations are derived. The present correctly labeled coupled-states theory is tested by comparing its calculated results with other computed results for three cases: H2-H2 collisions, ortho-para H2-H2 scattering, and H2-HCl.

  6. Binary star formation: gravitational fragmentation followed by capture

    NASA Astrophysics Data System (ADS)

    Turner, J. A.; Chapman, S. J.; Bhattal, A. S.; Disney, M. J.; Pongracic, H.; Whitworth, A. P.

    1995-11-01

    We describe in detail one of a sequence of numerical simulations which realize the mechanism of binary star formation proposed by Pringle. In these simulations, collisions between stable molecular cloud clumps produce dense shocked layers, which cool radiatively and fragment gravitationally. The resulting fragments then condense to form protostellar discs, which at the same time fall together and, as a result of tidal and viscous interactions, capture one another to form binary systems. We refer to this mechanism as shock-induced gravitational fragmentation followed by capture, or SGF+C. When the initial clumps are sufficiently massive and/or the Mach number of the collision is sufficiently high, a large number (>~10) of protostellar discs is produced; under these circumstances, the layer fragments first into filaments, and then into beads along the filaments. The marriage of two protostellar discs in this way is `arranged' in the sense that the protostellar discs involved do not form independently. First, they both condense out of the same layer, and probably also out of the same filament within this layer; this significantly increases the likelihood of them interacting dynamically. Secondly, there tends to be alignment between the orbital and spin angular momenta of the interacting protostellar discs, reflecting the fact that these angular momenta derive mainly from the systematic global angular momentum of the off-axis collision which produced the layer; this alignment of the various angular momenta pre-disposes the discs to very dissipative interactions, thereby increasing the probability of producing a strongly bound, long-lasting union. It is a marriage because the binary orbit stabilizes itself rather quickly. Any subsequent orbit evolution, as the protostellar discs `mop up' the surrounding residual gas and interact tidally, tends to harden the orbit. Therefore, as long as a third body does not intervene, the union is binding. Even if a third body does

  7. Binary nucleation kinetics. I. Self-consistent size distribution

    SciTech Connect

    Wilemski, G.; Wyslouzil, B.E. ||

    1995-07-15

    Using the principle of detailed balance, we derive a new self-consistency requirement, termed the kinetic product rule, relating the evaporation coefficients and equilibrium cluster distribution for a binary system. We use this result to demonstrate and resolve an inconsistency for an idealized Kelvin model of nucleation in a simple binary mixture. We next examine several common forms for the equilibrium distribution of binary clusters based on the capillarity approximation and ideal vapor behavior. We point out fundamental deficiencies for each expression. We also show that each distribution yields evaporation coefficients that formally satisfy the new kinetic product rule but are physically unsatisfactory because they depend on the monomer vapor concentrations. We then propose a new form of the binary distribution function that is free of the deficiencies of the previous functions except for its reliance on the capillarity approximation. This new self-consistent classical (SCC) size distribution for binary clusters has the following properties: It satisfies the law of mass action; it reduces to an SCC unary distribution for clusters of a single component; and it produces physically acceptable evaporation rate coefficients that also satisfy the new kinetic product rule. Since it is possible to construct other examples of similarly well-behaved distributions, our result is not unique in this respect, but it does give reasonable predictions. As an illustration, we calculate binary nucleation rates and vapor activities for the ethanol--hexanol system at 260 K using the new SCC distribution and compare them to experimental results. The theoretical rates are uniformly higher than the experimental values over the entire vapor composition range. Although the predicted activities are lower, we find good agreement between the measured and theoretical slope of the critical vapor activity curve at a constant nucleation rate of 10{sup 7} cm{sup {minus}3} s{sup {minus}2}.

  8. Approximating Functions with Exponential Functions

    ERIC Educational Resources Information Center

    Gordon, Sheldon P.

    2005-01-01

    The possibility of approximating a function with a linear combination of exponential functions of the form e[superscript x], e[superscript 2x], ... is considered as a parallel development to the notion of Taylor polynomials which approximate a function with a linear combination of power function terms. The sinusoidal functions sin "x" and cos "x"…

  9. 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

  10. Algorithm Plans Collision-Free Path for Robotic Manipulator

    NASA Technical Reports Server (NTRS)

    Backes, Paul; Diaz-Calderon, Antonio

    2007-01-01

    An algorithm has been developed to enable a computer aboard a robot to autonomously plan the path of the manipulator arm of the robot to avoid collisions between the arm and any obstacle, which could be another part of the robot or an external object in the vicinity of the robot. In simplified terms, the algorithm generates trial path segments and tests each segment for potential collisions in an iterative process that ends when a sequence of collision-free segments reaches from the starting point to the destination. The main advantage of this algorithm, relative to prior such algorithms, is computational efficiency: the algorithm is designed to make minimal demands upon the limited computational resources available aboard a robot. This path-planning algorithm utilizes a modified version of the collision-detection method described in "Improved Collision-Detection Method for Robotic Manipulator" (NPO-30356), NASA Tech Briefs, Vol. 27, No. 3 (June 2003), page 72. The method involves utilization of mathematical models of the robot constructed prior to operation and similar models of external objects constructed automatically from sensory data acquired during operation. This method incorporates a previously developed method, known in the art as the method of oriented bounding boxes (OBBs), in which an object is represented approximately, for computational purposes, by a box that encloses its outer boundary. Because many parts of a robotic manipulator are cylindrical, the OBB method has been extended in this method to enable the approximate representation of cylindrical parts by use of octagonal or other multiple-OBB assemblies denoted oriented bounding prisms (OBPs). A multiresolution OBB/OBP representation of the robot and its manipulator arm and a multiresolution OBB representation of external objects (including terrain) are constructed and used in a process in which collisions at successively finer resolutions are detected through computational detection of overlaps

  11. Examining the exobase approximation: DSMC models of Titan's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Tucker, Orenthal J.; Waalkes, William; Tenishev, Valeriy M.; Johnson, Robert E.; Bieler, Andre; Combi, Michael R.; Nagy, Andrew F.

    2016-07-01

    Chamberlain ([1963] Planet. Space Sci., 11, 901-960) described the use of the exobase layer to determine escape from planetary atmospheres, below which it is assumed that molecular collisions maintain thermal equilibrium and above which collisions are deemed negligible. De La Haye et al. ([2007] Icarus., 191, 236-250) used this approximation to extract the energy deposition and non-thermal escape rates for Titan's atmosphere by fitting the Cassini Ion Neutral Mass Spectrometer (INMS) density data. De La Haye et al. assumed the gas distributions were composed of an enhanced population of super-thermal molecules (E >> kT) that could be described by a kappa energy distribution function (EDF), and they fit the data using the Liouville theorem. Here we fitted the data again, but we used the conventional form of the kappa EDF. The extracted kappa EDFs were then used with the Direct Simulation Monte Carlo (DSMC) technique (Bird [1994] Molecular Gas Dynamics and the Direct Simulation of Gas Flows) to evaluate the effect of collisions on the exospheric profiles. The INMS density data can be fit reasonably well with thermal and various non-thermal EDFs. However, the extracted energy deposition and escape rates are shown to depend significantly on the assumed exobase altitude, and the usefulness of such fits without directly modeling the collisions is unclear. Our DSMC results indicate that the kappa EDFs used in the Chamberlain approximation can lead to errors in determining the atmospheric temperature profiles and escape rates. Gas kinetic simulations are needed to accurately model measured exospheric density profiles, and to determine the altitude ranges where the Liouville method might be applicable.

  12. Approximate circuits for increased reliability

    DOEpatents

    Hamlet, Jason R.; Mayo, Jackson R.

    2015-12-22

    Embodiments of the invention describe a Boolean circuit having a voter circuit and a plurality of approximate circuits each based, at least in part, on a reference circuit. The approximate circuits are each to generate one or more output signals based on values of received input signals. The voter circuit is to receive the one or more output signals generated by each of the approximate circuits, and is to output one or more signals corresponding to a majority value of the received signals. At least some of the approximate circuits are to generate an output value different than the reference circuit for one or more input signal values; however, for each possible input signal value, the majority values of the one or more output signals generated by the approximate circuits and received by the voter circuit correspond to output signal result values of the reference circuit.

  13. Approximate circuits for increased reliability

    SciTech Connect

    Hamlet, Jason R.; Mayo, Jackson R.

    2015-08-18

    Embodiments of the invention describe a Boolean circuit having a voter circuit and a plurality of approximate circuits each based, at least in part, on a reference circuit. The approximate circuits are each to generate one or more output signals based on values of received input signals. The voter circuit is to receive the one or more output signals generated by each of the approximate circuits, and is to output one or more signals corresponding to a majority value of the received signals. At least some of the approximate circuits are to generate an output value different than the reference circuit for one or more input signal values; however, for each possible input signal value, the majority values of the one or more output signals generated by the approximate circuits and received by the voter circuit correspond to output signal result values of the reference circuit.

  14. A Coulomb collision algorithm for weighted particle simulations

    NASA Technical Reports Server (NTRS)

    Miller, Ronald H.; Combi, Michael R.

    1994-01-01

    A binary Coulomb collision algorithm is developed for weighted particle simulations employing Monte Carlo techniques. Charged particles within a given spatial grid cell are pair-wise scattered, explicitly conserving momentum and implicitly conserving energy. A similar algorithm developed by Takizuka and Abe (1977) conserves momentum and energy provided the particles are unweighted (each particle representing equal fractions of the total particle density). If applied as is to simulations incorporating weighted particles, the plasma temperatures equilibrate to an incorrect temperature, as compared to theory. Using the appropriate pairing statistics, a Coulomb collision algorithm is developed for weighted particles. The algorithm conserves energy and momentum and produces the appropriate relaxation time scales as compared to theoretical predictions. Such an algorithm is necessary for future work studying self-consistent multi-species kinetic transport.

  15. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1997-01-01

    Electrophoresis has long been recognized as an effective analytic technique for the separation of proteins and other charged species, however attempts at scaling up to accommodate commercial volumes have met with limited success. In this report we describe a novel electrophoretic separation technique - Binary Oscillatory Crossflow Electrophoresis (BOCE). Numerical simulations indicate that the technique has the potential for preparative scale throughputs with high resolution, while simultaneously avoiding many problems common to conventional electrophoresis. The technique utilizes the interaction of an oscillatory electric field and a transverse oscillatory shear flow to create an active binary filter for the separation of charged protein species. An oscillatory electric field is applied across the narrow gap of a rectangular channel inducing a periodic motion of charged protein species. The amplitude of this motion depends on the dimensionless electrophoretic mobility, alpha = E(sub o)mu/(omega)d, where E(sub o) is the amplitude of the electric field oscillations, mu is the dimensional mobility, omega is the angular frequency of oscillation and d is the channel gap width. An oscillatory shear flow is induced along the length of the channel resulting in the separation of species with different mobilities. We present a model that predicts the oscillatory behavior of charged species and allows estimation of both the magnitude of the induced convective velocity and the effective diffusivity as a function of a in infinitely long channels. Numerical results indicate that in addition to the mobility dependence, the steady state behavior of solute species may be strongly affected by oscillating fluid into and out of the active electric field region at the ends of the cell. The effect is most pronounced using time dependent shear flows of the same frequency (cos((omega)t)) flow mode) as the electric field oscillations. Under such conditions, experiments indicate that

  16. USING KUIPER BELT BINARIES TO CONSTRAIN NEPTUNE'S MIGRATION HISTORY

    SciTech Connect

    Murray-Clay, Ruth A.; Schlichting, Hilke E.

    2011-04-01

    Approximately 10%-20% of all Kuiper Belt objects (KBOs) occupy mean-motion resonances with Neptune. This dynamical configuration likely resulted from resonance capture as Neptune migrated outward during the late stages of planet formation. The details of Neptune's planetesimal-driven migration, including its radial extent and the concurrent eccentricity evolution of the planet, are the subject of considerable debate. Two qualitatively different proposals for resonance capture have been proposed-migration-induced capture driven by smooth outward evolution of Neptune's orbit and chaotic capture driven by damping of the planet's eccentricity near its current semi-major axis. We demonstrate that the distribution of comparable-mass, wide-separation binaries occupying resonant orbits can differentiate between these two scenarios. If migration-induced capture occurred, this fraction records information about the formation locations of different populations of KBOs. Chaotic capture, in contrast, randomizes the orbits of bodies as they are placed in resonance. In particular, if KBO binaries are formed by dynamical capture in a protoplanetary disk with a surface mass density typical of observed extrasolar disks, then migration-induced capture produces the following signatures. The 2:1 resonance should contain a dynamically cold component, with inclinations less than 5{sup 0}-10{sup 0}, having a binary fraction comparable to that among cold classical KBOs. If the 3:2 resonance also hosts a cold component, its binary fraction should be 20%-30% lower than in the cold classical belt. Among cold 2:1 (and if present 3:2) KBOs, objects with eccentricities e < 0.2 should have a binary fraction {approx}20% larger than those with e>0.2. Other binary formation scenarios and disk surface density profiles can generate analogous signatures but produce quantitatively different results. Searches for cold components in the binary fractions of resonant KBOs are currently practical. The

  17. 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

  18. Stability of binaries. Part II: Rubble-pile binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2016-10-01

    We consider the stability of the binary asteroids whose members are granular aggregates held together by self-gravity alone. A binary is said to be stable whenever both its members are orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability analysis of Sharma (Sharma [2015] Icarus, 258, 438-453), that is applicable to binaries with rigid members, to the case of binary systems with rubble members. We employ volume averaging (Sharma et al. [2009] Icarus, 200, 304-322), which was inspired by past work on elastic/fluid, rotating and gravitating ellipsoids. This technique has shown promise when applied to rubble-pile ellipsoids, but requires further work to settle some of its underlying assumptions. The stability test is finally applied to some suspected binary systems, viz., 216 Kleopatra, 624 Hektor and 90 Antiope. We also see that equilibrated binaries that are close to mobilizing their maximum friction can sustain only a narrow range of shapes and, generally, congruent shapes are preferred.

  19. Binary star database: binaries discovered in non-optical bands

    NASA Astrophysics Data System (ADS)

    Malkov, Oleg Yu.; Tessema, Solomon B.; Kniazev, Alexei Yu.

    The Binary star Database (BDB) is the world's principal database of binary and multiple systems of all observational types. In particular, it should contain data on binaries discovered in non-optical bands, X-ray binaries (XRBs) and radio pulsars in binaries. The goal of the present study was to compile complete lists of such objects. Due to the lack of a unified identification system for XRBs, we had to select them from five principal catalogues of X-ray sources. After cross-identification and positional cross-matching, a general catalogue of 373 XRBs was constructed for the first time. It contains coordinates, indication of photometric and spectroscopic binarity, and extensive cross-identification. In the preparation of the catalogue, a number of XRB classification disagreements were resolved, some catalogued identifiers and coordinates were corrected, and duplicated entries in the original catalogues were found. We have also compiled a general list of 239 radio pulsars in binary systems. The list is supplied with indication of photometric, spectroscopic or X-ray binarity, and with cross-identification data.

  20. Binary Cepheids: Separations and Mass Ratios in 5 Solar Mass Binaries

    DTIC Science & Technology

    2013-10-01

    material: color figures 1. INTRODUCTION Binary-star studies are valuable for what they provide directly (e.g., stellar masses), as well as for the...the high stellar density in the cluster, this could be a chance alignment. 3.2.2. Approximate Orbital Periods We used the angular separations in Table...subsequent evolution of the system will be drastically altered. For Cepheids we have a good estimation of where this effect sets in. Z Lac—not in our sample

  1. Binary black hole spectroscopy

    NASA Astrophysics Data System (ADS)

    Van Den Broeck, Chris; Sengupta, Anand S.

    2007-03-01

    We study parameter estimation with post-Newtonian (PN) gravitational waveforms for the quasi-circular, adiabatic inspiral of spinning binary compact objects. In particular, the performance of amplitude-corrected waveforms is compared with that of the more commonly used restricted waveforms, in Advanced LIGO and EGO. With restricted waveforms, the properties of the source can only be extracted from the phasing. In the case of amplitude-corrected waveforms, the spectrum encodes a wealth of additional information, which leads to dramatic improvements in parameter estimation. At distances of ~100 Mpc, the full PN waveforms allow for high-accuracy parameter extraction for total mass up to several hundred solar masses, while with the restricted ones the errors are steep functions of mass, and accurate parameter estimation is only possible for relatively light stellar mass binaries. At the low-mass end, the inclusion of amplitude corrections reduces the error on the time of coalescence by an order of magnitude in Advanced LIGO and a factor of 5 in EGO compared to the restricted waveforms; at higher masses these differences are much larger. The individual component masses, which are very poorly determined with restricted waveforms, become measurable with high accuracy if amplitude-corrected waveforms are used, with errors as low as a few per cent in Advanced LIGO and a few tenths of a per cent in EGO. The usual spin orbit parameter β is also poorly determined with restricted waveforms (except for low-mass systems in EGO), but the full waveforms give errors that are small compared to the largest possible value consistent with the Kerr bound. This suggests a way of finding out if one or both of the component objects violate this bound. On the other hand, we find that the spin spin parameter σ remains poorly determined even when the full waveform is used. Generally, all errors have but a weak dependence on the magnitudes and orientations of the spins. We also briefly

  2. Binary black hole coalescence in semianalytic puncture evolution

    SciTech Connect

    Gopakumar, Achamveedu; Schaefer, Gerhard

    2008-05-15

    Binary black hole coalescence is treated semianalytically by a novel approach. Our prescription employs the conservative Skeleton Hamiltonian that describes orbiting Brill-Lindquist wormholes (termed punctures in numerical relativity) within a waveless truncation to the Einstein field equations [G. Faye, P. Jaranowski, and G. Schaefer, Phys. Rev. D 69, 124029 (2004)]. We incorporate, in a transparent Hamiltonian way and in Burke-Thorne gauge structure, the effects of gravitational radiation reaction into the above Skeleton dynamics with the help of 3.5PN accurate angular momentum flux for compact binaries in quasicircular orbits to obtain a semianalytic puncture evolution to model merging black hole binaries. With the help of the TaylorT4 approximant at 3.5PN order, we perform a first-order comparison between gravitational-wave phase evolutions in numerical relativity and our approach for equal-mass binary black holes. This comparison reveals that a modified Skeletonian reactive dynamics that employs flexible parameters will be required to prevent the dephasing between our scheme and numerical relativity, similar to what is pursued in the effective one-body approach. A rough estimate for the gravitational waveform associated with the binary black hole coalescence in our approach is also provided.

  3. Domain walls and bubble droplets in immiscible binary Bose gases

    NASA Astrophysics Data System (ADS)

    Filatrella, G.; Malomed, Boris A.; Salerno, Mario

    2014-10-01

    The existence and stability of domain walls (DWs) and bubble-droplet (BD) states in binary mixtures of quasi-one-dimensional ultracold Bose gases with inter- and intraspecies repulsive interactions is considered. Previously, DWs were studied by means of coupled systems of Gross-Pitaevskii equations (GPEs) with cubic terms, which model immiscible binary Bose-Einstein condensates (BECs). We address immiscible BECs with two- and three-body repulsive interactions, as well as binary Tonks-Girardeau (TG) gases, using systems of GPEs with cubic and quintic nonlinearities for the binary BEC, and coupled nonlinear Schrödinger equations with quintic terms for the TG gases. Exact DW solutions are found for the symmetric BEC mixture, with equal intraspecies scattering lengths. Stable asymmetric DWs in the BEC mixtures with dissimilar interactions in the two components, as well as of symmetric and asymmetric DWs in the binary TG gas, are found by means of numerical and approximate analytical methods. In the BEC system, DWs can be easily put in motion by phase imprinting. Combining a DW and anti-DW on a ring, we construct BD states for both the BEC and TG models. These consist of a dark soliton in one component (the "bubble"), and a bright soliton (the "droplet") in the other. In the BEC system, these composite states are mobile, too.

  4. Extrasolar binary planets. I. Formation by tidal capture during planet-planet scattering

    SciTech Connect

    Ochiai, H.; Nagasawa, M.; Ida, S.

    2014-08-01

    We have investigated (1) the formation of gravitationally bounded pairs of gas-giant planets (which we call 'binary planets') from capturing each other through planet-planet dynamical tide during their close encounters and (2) the subsequent long-term orbital evolution due to planet-planet and planet-star quasi-static tides. For the initial evolution in phase 1, we carried out N-body simulations of the systems consisting of three Jupiter-mass planets taking into account the dynamical tide. The formation rate of the binary planets is as much as 10% of the systems that undergo orbital crossing, and this fraction is almost independent of the initial stellarcentric semimajor axes of the planets, while ejection and merging rates sensitively depend on the semimajor axes. As a result of circularization by the planet-planet dynamical tide, typical binary separations are a few times the sum of the physical radii of the planets. After the orbital circularization, the evolution of the binary system is governed by long-term quasi-static tide. We analytically calculated the quasi-static tidal evolution in phase 2. The binary planets first enter the spin-orbit synchronous state by the planet-planet tide. The planet-star tide removes angular momentum of the binary motion, eventually resulting in a collision between the planets. However, we found that the binary planets survive the tidal decay for the main-sequence lifetime of solar-type stars (∼10 Gyr), if the binary planets are beyond ∼0.3 AU from the central stars. These results suggest that the binary planets can be detected by transit observations at ≳ 0.3 AU.

  5. Modeling collisions in circumstellar debris disks

    NASA Astrophysics Data System (ADS)

    Nesvold, Erika

    2015-10-01

    resonances near the chaotic zone. I investigate the effects of the initial eccentricity distribution of the disk particles and find a negligible effect on the gap size at Jovian planet masses, since collisions tend to erase memory of the initial particle eccentricity distributions. I also find that the presence of Trojan analogs is a potentially powerful diagnostic of planets in the mass range ˜1--10MJup. I apply my model to place new upper limits on planets around Fomalhaut, HR 4796 A, HD 202628, HD 181327, and beta Pictoris. Finally, to show how SMACK can be used to analyze a single debris disk in detail, I present a new model of the beta Pictoris disk and planet system that, for the first time, combines simulations of the colliding planetesimals and the dynamics of the dust grains, allowing me to model features and asymmetries in both submillimeter and scattered light images of the disk. I combine a 100,000 superparticle SMACK simulation with N-body integrations of the dust produced by the simulated collisions. I find that secular perturbations of the planet's measured inclination and eccentricity can explain the observed warp and planetesimal ring, while collisions between planetesimals shape the disk by eroding close-in material. The complex 3D structure of the disk due to the perturbations from the planet creates an azimuthally asymmetric spatial distribution of collisions, which could contribute to the observed azimuthal clump of CO gas seen with ALMA. My simulations of the small dust grains produced by collisions demonstrate that the "birth ring" approximation for beta Pictoris fails to account for the ˜54% of dust mass produced outside of the planetesimal ring. I also reproduce the gross morphology of high-resolution scattered light images of the disk, including the two-disk "x"-pattern seen in scattered light, which has not been replicated by previous dust dynamics models.

  6. Observation of D0 Meson Nuclear Modifications in Au +Au Collisions at √sNN =200 GeV

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2014-10-01

    We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K-+π+) in Au +Au collisions at √sNN =200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p +p to central Au +Au collisions. The D0 meson yields in central Au +Au collisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT>3 GeV /c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate pT is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.

  7. Separation in 5 Msun Binaries

    NASA Astrophysics Data System (ADS)

    Evans, Nancy R.; Bond, H. E.; Schaefer, G.; Mason, B. D.; Karovska, M.; Tingle, E.

    2013-01-01

    Cepheids (5 Msun stars) provide an excellent sample for determining the binary properties of fairly massive stars. International Ultraviolet Explorer (IUE) observations of Cepheids brighter than 8th magnitude resulted in a list of ALL companions more massive than 2.0 Msun uniformly sensitive to all separations. Hubble Space Telescope Wide Field Camera 3 (WFC3) has resolved three of these binaries (Eta Aql, S Nor, and V659 Cen). Combining these separations with orbital data in the literature, we derive an unbiased distribution of binary separations for a sample of 18 Cepheids, and also a distribution of mass ratios. The distribution of orbital periods shows that the 5 Msun binaries prefer shorter periods than 1 Msun stars, reflecting differences in star formation processes.

  8. CHAOTIC ZONES AROUND GRAVITATING BINARIES

    SciTech Connect

    Shevchenko, Ivan I.

    2015-01-20

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound primaries of comparable masses (a binary star, a binary black hole, a binary asteroid, etc.) is estimated analytically, as a function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges (above a threshold in the primaries' mass ratio) due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the central binary periods. In this zone, the unlimited chaotic orbital diffusion of the tertiary takes place, up to its ejection from the system. The primaries' mass ratio, above which such a chaotic zone is universally present at all initial eccentricities of the tertiary, is estimated. The diversity of the observed orbital configurations of biplanetary and circumbinary exosystems is shown to be in accord with the existence of the primaries' mass parameter threshold.

  9. Cryptography with DNA binary strands.

    PubMed

    Leier, A; Richter, C; Banzhaf, W; Rauhe, H

    2000-06-01

    Biotechnological methods can be used for cryptography. Here two different cryptographic approaches based on DNA binary strands are shown. The first approach shows how DNA binary strands can be used for steganography, a technique of encryption by information hiding, to provide rapid encryption and decryption. It is shown that DNA steganography based on DNA binary strands is secure under the assumption that an interceptor has the same technological capabilities as sender and receiver of encrypted messages. The second approach shown here is based on steganography and a method of graphical subtraction of binary gel-images. It can be used to constitute a molecular checksum and can be combined with the first approach to support encryption. DNA cryptography might become of practical relevance in the context of labelling organic and inorganic materials with DNA 'barcodes'.

  10. An adaptable binary entropy coder

    NASA Technical Reports Server (NTRS)

    Kiely, A.; Klimesh, M.

    2001-01-01

    We present a novel entropy coding technique which is based on recursive interleaving of variable-to-variable length binary source codes. We discuss code design and performance estimation methods, as well as practical encoding and decoding algorithms.

  11. Vibrational and rotational transitions in low-energy electron-diatomic-molecule collisions. I - Close-coupling theory in the moving body-fixed frame. II - Hybrid theory and close-coupling theory: An /l subscript z-prime/-conserving close-coupling approximation

    NASA Technical Reports Server (NTRS)

    Choi, B. H.; Poe, R. T.

    1977-01-01

    A detailed vibrational-rotational (V-R) close-coupling formulation of electron-diatomic-molecule scattering is developed in which the target molecular axis is chosen to be the z-axis and the resulting coupled differential equation is solved in the moving body-fixed frame throughout the entire interaction region. The coupled differential equation and asymptotic boundary conditions in the body-fixed frame are given for each parity, and procedures are outlined for evaluating V-R transition cross sections on the basis of the body-fixed transition and reactance matrix elements. Conditions are discussed for obtaining identical results from the space-fixed and body-fixed formulations in the case where a finite truncated basis set is used. The hybrid theory of Chandra and Temkin (1976) is then reformulated, relevant expressions and formulas for the simultaneous V-R transitions of the hybrid theory are obtained in the same forms as those of the V-R close-coupling theory, and distorted-wave Born-approximation expressions for the cross sections of the hybrid theory are presented. A close-coupling approximation that conserves the internuclear axis component of the incident electronic angular momentum (l subscript z-prime) is derived from the V-R close-coupling formulation in the moving body-fixed frame.

  12. 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.

  13. 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

  14. The fixation probability of a beneficial allele in a population dividing by binary fission.

    PubMed

    Johnson, Toby; Gerrish, Philip J

    2002-08-01

    We derive formulae for the fixation probability, P, of a rare benefical allele segregating in a population of fixed size which reproduces by binary fission, in terms of the selection coefficient for the beneficial allele, s. We find that an earlier result P approximately = 4s does not depend on the assumption of binary fission, but depends on an assumption about the ordering of events in the life cycle. We find that P approximately = 2s for mutations occurring during chromosome replication and P approximately = 2.8s for mutations occurring at random times between replication events.

  15. Approximating subtree distances between phylogenies.

    PubMed

    Bonet, Maria Luisa; St John, Katherine; Mahindru, Ruchi; Amenta, Nina

    2006-10-01

    We give a 5-approximation algorithm to the rooted Subtree-Prune-and-Regraft (rSPR) distance between two phylogenies, which was recently shown to be NP-complete. This paper presents the first approximation result for this important tree distance. The algorithm follows a standard format for tree distances. The novel ideas are in the analysis. In the analysis, the cost of the algorithm uses a "cascading" scheme that accounts for possible wrong moves. This accounting is missing from previous analysis of tree distance approximation algorithms. Further, we show how all algorithms of this type can be implemented in linear time and give experimental results.

  16. Hybrid Long-Range Collision Avoidance for Crowd Simulation.

    PubMed

    Golas, Abhinav; Narain, Rahul; Curtis, Sean; Lin, Ming C

    2014-07-01

    Local collision avoidance algorithms in crowd simulation often ignore agents beyond a neighborhood of a certain size. This cutoff can result in sharp changes in trajectory when large groups of agents enter or exit these neighborhoods. In this work, we exploit the insight that exact collision avoidance is not necessary between agents at such large distances, and propose a novel algorithm for extending existing collision avoidance algorithms to perform approximate, long-range collision avoidance. Our formulation performs long-range collision avoidance for distant agent groups to efficiently compute trajectories that are smoother than those obtained with state-of-the-art techniques and at faster rates. Comparison to real-world data demonstrates that crowds simulated with our algorithm exhibit an improved speed sensitivity to density similar to human crowds. Another issue often sidestepped in existing work is that discrete and continuum collision avoidance algorithms have different regions of applicability. For example, low-density crowds cannot be modeled as a continuum, while high-density crowds can be expensive to model using discrete methods. We formulate a hybrid technique for crowd simulation which can accurately and efficiently simulate crowds at any density with seamless transitions between continuum and discrete representations. Our approach blends results from continuum and discrete algorithms, based on local density and velocity variance. In addition to being robust across a variety of group scenarios, it is also highly efficient, running at interactive rates for thousands of agents on portable systems.

  17. Hybrid Long-Range Collision Avoidance for Crowd Simulation.

    PubMed

    Golas, Abhinav; Narain, Rahul; Curtis, Sean; Lin, Ming C

    2013-09-26

    Local collision avoidance algorithms in crowd simulation often ignore agents beyond a neighborhood of a certain size. This cutoff can result in sharp changes in trajectory when large groups of agents enter or exit these neighborhoods. In this work, we exploit the insight that exact collision avoidance is not necessary between agents at such large distances, and propose a novel algorithm for extending existing collision avoidance algorithms to perform approximate, long-range collision avoidance. Our formulation performs long-range collision avoidance for distant agent groups to efficiently compute trajectories that are smoother than those obtained with state-of-the-art techniques and at faster rates. Another issue often sidestepped in existing work is that discrete and continuum collision avoidance algorithms have different regions of applicability. For example, low-density crowds cannot be modeled as a continuum, while high-density crowds can be expensive to model using discrete methods. We formulate a hybrid technique for crowd simulation which can accurately and efficiently simulate crowds at any density with seamless transitions between continuum and discrete representations. Our approach blends results from continuum and discrete algorithms, based on local density and velocity variance. In addition to being robust across a variety of group scenarios, it is also highly efficient, running at interactive rates for thousands of agents on portable systems.

  18. Development of an in-vehicle intersection collision countermeasure

    NASA Astrophysics Data System (ADS)

    Pierowicz, John

    1997-02-01

    Intersection collisions constitute approximately twenty-six percent of all accidents in the United States. Because of their complexity, and demands on the perceptual and decision making abilities of the driver, intersections present an increased risk of collisions between automobiles. This situation provides an opportunity to apply advanced sensor and processing capabilities to prevent these collisions. A program to determine the characteristics of intersection collisions and identify potential countermeasures will be described. This program, sponsored by the National Highway Traffic Safety Administration, utilized accident data to develop a taxonomy of intersection crashes. This taxonomy was used to develop a concept for an intersection collision avoidance countermeasure. The concept utilizes in-vehicle position, dynamic status, and millimeter wave radar system and an in-vehicle computer system to provide inputs to an intersection collision avoidance algorithm. Detection of potential violation of traffic control device, or proceeding into the intersection with inadequate gap will lead to the presentation of a warning to the driver. These warnings are presented to the driver primarily via a head-up display and haptic feedback. Roadside to vehicle communication provides information regarding phased traffic signal information. Active control of the vehicle's brake and steering systems are described. Progress in the development of the systems will be presented along with the schedule of future activities.

  19. Ionization Phenomena in Ion-Atom Collisions

    NASA Astrophysics Data System (ADS)

    Deveney, Edward Francis

    Two many-electron ion-atom collision systems are used to investigate atomic and molecular structure and collisional interactions. Electrons emitted from MeV/u C^{3+} projectile target -atom collisions were measured with a high-resolution position -sensitive electron spectrometer at Oak Ridge National Laboratory. The electrons are predominantly ionized by direct projectile -target interactions or autoionizing (AI) from doubly excited AI levels of the ion which were excited in the collision. The energy dependence of directly scattered target electrons, binary-encounter electrons (BEE), is investigated and compared with theory. AI levels of the projectile 1s to nl single electron excited series, (1s2snl) n = 2,3,4,....infty, including the series limit are identified uniquely using energy level calculations. Original Auger yield calculations using a code by Cowan were used to discover a 1/{n^3} scaling in intensities of Auger peaks in the aforementioned series. This is explained using scattering theory. A nonstatistical population of the terms in the (1s2s2l) configuration was identified and investigated as a function of the beam energy and for four different target atoms. Two electron excited configurations are identified and investigated. The angular distribution of a correlated transfer and excitation AI state is measured and compared to theory. The final scattered charge state distributions of Kr^ {n+}, n = 1, 2, 3, 4, 5, projectiles are measured following collisions with Kr targets in the Van de Graaff Laboratory here at The University of Connecticut. Average scattered charge states as high as 12 are observed. It appears that these electrons are ionized during the lifetime of the quasimolecular state but a complete picture of the ionization mechanism(s) is not known. Calculations using a statistical model of ionization, modified in several ways, are compared with the experimental results to see if it is possible to isolate whether or not the electrons originate

  20. γ-ray Binaries : A Bridge Between Be Stars and High Energy Astrophysics Invited Review

    NASA Astrophysics Data System (ADS)

    Lamberts, A.

    2016-11-01

    Advances in X-ray and gamma-ray astronomy have opened a new window on our universe and revealed a wide variety of binaries composed of a compact object and a Be star. In Be X-ray binaries, a neutron star accretes the Be disk and truncates it through tidal interactions. Such systems have important X-ray outbursts, some related to the disk structure. In other systems, strong gamma-ray emission is observed. In γ-ray binaries, the neutron star is not accreting but driving a highly relativistic wind. The wind collision region presents similarities to colliding wind binaries composed of massive stars. The high energy emission is coming from particles being accelerated at the relativistic shock. I will review the physics of X-ray and gamma-ray binaries, focusing particularly on the recent developments on gamma-ray binaries. I will describe physical mechanisms such as relativistic hydrodynamics, tidal forces and non thermal emission. I will highlight how high energy astrophysics can shed a new light on Be star physics and vice-versa.

  1. 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.

  2. 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.

  3. 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.

  4. Dual approximations in optimal control

    NASA Technical Reports Server (NTRS)

    Hager, W. W.; Ianculescu, G. D.

    1984-01-01

    A dual approximation for the solution to an optimal control problem is analyzed. The differential equation is handled with a Lagrange multiplier while other constraints are treated explicitly. An algorithm for solving the dual problem is presented.

  5. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    SciTech Connect

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  6. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    DOE PAGES

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we alsomore » show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.« less

  7. Azimuthal Anisotropy in U+U and Au+Au Collisions at RHIC.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandin, A V; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Cervantes, M C; Chakaberia, I; Chaloupka, P; Chang, Z; Chattopadhyay, S; 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; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, H Z; Huang, B; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Kosarzewski, L K; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, W; Li, Y; Li, C; Li, Z M; Li, X; Li, X; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, L; Ma, R; Ma, Y G; Ma, G L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; Meehan, K; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V; Olvitt, D L; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Peterson, A; Pile, P; Planinic, M; Pluta, J; Poljak, N; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Sharma, M K; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Skoby, M J; Smirnov, D; Smirnov, N; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B J; Sun, X; Sun, X M; Sun, Z; Sun, Y; Surrow, B; Svirida, D N; Szelezniak, M A; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A N; Thomas, J H; Timmins, A R; Tlusty, D; 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; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbaek, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, Y; Wang, H; Wang, J S; Wang, Y; Wang, G; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, Y F; Xu, N; Xu, Z; Xu, Q H; Xu, H; Yang, Y; Yang, Y; Yang, C; Yang, S; Yang, Q; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, J B; Zhang, J; Zhang, Z; Zhang, S; Zhang, Y; Zhang, J L; Zhao, F; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M

    2015-11-27

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v_{2}{2} and v_{2}{4}, for charged hadrons from U+U collisions at sqrt[s_{NN}]=193  GeV and Au+Au collisions at sqrt[s_{NN}]=200  GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v_{2}{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. We also show that v_{2} vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  8. Mathematical algorithms for approximate reasoning

    NASA Technical Reports Server (NTRS)

    Murphy, John H.; Chay, Seung C.; Downs, Mary M.

    1988-01-01

    Most state of the art expert system environments contain a single and often ad hoc strategy for approximate reasoning. Some environments provide facilities to program the approximate reasoning algorithms. However, the next generation of expert systems should have an environment which contain a choice of several mathematical algorithms for approximate reasoning. To meet the need for validatable and verifiable coding, the expert system environment must no longer depend upon ad hoc reasoning techniques but instead must include mathematically rigorous techniques for approximate reasoning. Popular approximate reasoning techniques are reviewed, including: certainty factors, belief measures, Bayesian probabilities, fuzzy logic, and Shafer-Dempster techniques for reasoning. A group of mathematically rigorous algorithms for approximate reasoning are focused on that could form the basis of a next generation expert system environment. These algorithms are based upon the axioms of set theory and probability theory. To separate these algorithms for approximate reasoning various conditions of mutual exclusivity and independence are imposed upon the assertions. Approximate reasoning algorithms presented include: reasoning with statistically independent assertions, reasoning with mutually exclusive assertions, reasoning with assertions that exhibit minimum overlay within the state space, reasoning with assertions that exhibit maximum overlay within the state space (i.e. fuzzy logic), pessimistic reasoning (i.e. worst case analysis), optimistic reasoning (i.e. best case analysis), and reasoning with assertions with absolutely no knowledge of the possible dependency among the assertions. A robust environment for expert system construction should include the two modes of inference: modus ponens and modus tollens. Modus ponens inference is based upon reasoning towards the conclusion in a statement of logical implication, whereas modus tollens inference is based upon reasoning away

  9. Exponential approximations in optimal design

    NASA Technical Reports Server (NTRS)

    Belegundu, A. D.; Rajan, S. D.; Rajgopal, J.

    1990-01-01

    One-point and two-point exponential functions have been developed and proved to be very effective approximations of structural response. The exponential has been compared to the linear, reciprocal and quadratic fit methods. Four test problems in structural analysis have been selected. The use of such approximations is attractive in structural optimization to reduce the numbers of exact analyses which involve computationally expensive finite element analysis.

  10. A candidate sub-parsec supermassive binary black hole system.

    PubMed

    Boroson, Todd A; Lauer, Tod R

    2009-03-05

    The role of mergers in producing galaxies, together with the finding that most large galaxies harbour black holes in their nuclei, implies that binary supermassive black hole systems should be common. Here we report that the quasar SDSS J153636.22+044127.0 is a plausible example of such a system. This quasar shows two broad-line emission systems, separated in velocity by 3,500 km s(-1). A third system of unresolved absorption lines has an intermediate velocity. These characteristics are unique among known quasars. We interpret this object as a binary system of two black holes, having masses of 10(7.3) and 10(8.9) solar masses separated by approximately 0.1 parsec with an orbital period of approximately 100 years.

  11. Approximating random quantum optimization problems

    NASA Astrophysics Data System (ADS)

    Hsu, B.; Laumann, C. R.; Läuchli, A. M.; Moessner, R.; Sondhi, S. L.

    2013-06-01

    We report a cluster of results regarding the difficulty of finding approximate ground states to typical instances of the quantum satisfiability problem k-body quantum satisfiability (k-QSAT) on large random graphs. As an approximation strategy, we optimize the solution space over “classical” product states, which in turn introduces a novel autonomous classical optimization problem, PSAT, over a space of continuous degrees of freedom rather than discrete bits. Our central results are (i) the derivation of a set of bounds and approximations in various limits of the problem, several of which we believe may be amenable to a rigorous treatment; (ii) a demonstration that an approximation based on a greedy algorithm borrowed from the study of frustrated magnetism performs well over a wide range in parameter space, and its performance reflects the structure of the solution space of random k-QSAT. Simulated annealing exhibits metastability in similar “hard” regions of parameter space; and (iii) a generalization of belief propagation algorithms introduced for classical problems to the case of continuous spins. This yields both approximate solutions, as well as insights into the free energy “landscape” of the approximation problem, including a so-called dynamical transition near the satisfiability threshold. Taken together, these results allow us to elucidate the phase diagram of random k-QSAT in a two-dimensional energy-density-clause-density space.

  12. Neutrino Transport in Black Hole-Neutron Star Binaries: Dynamical Mass Ejection and Neutrino-Driven Wind

    NASA Astrophysics Data System (ADS)

    Kyutoku, K.; Kiuchi, K.; Sekiguchi, Y.; Shibata, M.; Taniguchi, K.

    2016-10-01

    We present our recent results of numerical-relativity simulations of black hole-neutron star binary mergers incorporating approximate neutrino transport. We in particular discuss dynamical mass ejection and neutrino-driven wind.

  13. Can binary stars test solar models?

    NASA Technical Reports Server (NTRS)

    Popper, D. M.; Ulrich, R. K.

    1986-01-01

    The position in the H-R diagram of the approximately solar-mass component of the Hyades eclipsing binary, HD 27130, is compared with the predictions of stellar structure theory. The stellar models are calibrated by matching a model with the solar heavy element composition and age to the solar radius and luminosity. The comparison to the Hyades binary then is a test of the prediction that the initial solar luminosity was only about 0.7 times the present solar luminosity. The agreement is satisfactory, lending a measure of confidence to the solar model employed, provided that the initial helium abundance of the Hyades stars is not greater than that of the sun and is not less by more than about 0.03 in Y. Unless the model is grossly incorrect, the inference of Stromgren, Olsen, and Gustafsson (1982) from the 'Hyades anomaly' in intermediate-band photometry that Y(Hyades) is less than Y(solar) by 0.1 or 0.15 is rejected by the observed properties of HD 27130.

  14. Analysis of the Interferometric Binary Finsen 332

    NASA Astrophysics Data System (ADS)

    Mason, Brian D.; Hartkopf, W. I.; McAlister, H. A.

    2010-01-01

    Two of the most challenging objects for optical interferometry in the middle of the last century were the close components (FIN 332) of the wide visual binary STF2375 (= WDS 18455+0530 = HIP 92027 = ADS 11640). Each component of the wide pair was found to have subcomponents of approximately the same magnitude, position angle and separation and, hence, were designated by the tongue in cheek monikers "Tweedledum and Tweedledee" by the great visual interferometrist William S. Finsen in 1953. They were later included in a list of "Double Stars that Vex the Observer" by W.H. van den Bos. While speckle interferometry has reaped a rich harvest investigating the close inteferometric binaries of Finsen, the "Tweedles" have continued to both fascinate and exasperate due to both the great similarity of the close pairs as well as the inherent 180 degree ambiguity associated with interferometry. Detailed analysis of all published observations of the system have revealed several errors which are here corrected, allowing for determination of these orbital elements which resolve the quadrant ambiguity. A unique software filter was developed which allowed subarrays from archival ICCD speckle data from 1982 to be re-reduced. Those data, combined with new and unpublished observations obtained in 2001-9 from NOAO 4m telescopes, the Mt. Wilson 100in telescope and the NOFS 61in telescope as well as high quality unresolved measures all allow for the correct orbits to be determined. Co-planarity of the multiple system is also investigated.

  15. 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.

  16. 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.

  17. Rapid formation of supermassive black hole binaries in galaxy mergers with gas.

    PubMed

    Mayer, L; Kazantzidis, S; Madau, P; Colpi, M; Quinn, T; Wadsley, J

    2007-06-29

    Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that after the merger of two massive galaxies, a SMBH binary will form, shrink because of stellar or gas dynamical processes, and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two SMBHs bind during a galaxy merger with gas because of the difficulty of modeling a wide range of spatial scales. Here we report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years after the collision between two spiral galaxies. A massive, turbulent, nuclear gaseous disk arises as a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than 1 million years as a result of the gravitational drag from the gas rather than from the stars.

  18. Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers with Gas

    SciTech Connect

    Mayer, L.; Kazantzidis, S.; Madau, P.; Colpi, M.; Quinn, T.; Wadsley, J.; /McMaster U.

    2008-03-24

    Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that, following the merger of two massive galaxies, a SMBH binary will form, shrink due to stellar or gas dynamical processes and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two SMBHs bind during a galaxy merger with gas due to the difficulty of modeling a wide range of spatial scales. Here we report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years following the collision between two spiral galaxies. A massive, turbulent nuclear gaseous disk arises as a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than a million years as a result of the gravitational drag from the gas rather than from the stars.

  19. The evolution of highly compact binary stellar systems in globular clusters

    NASA Technical Reports Server (NTRS)

    Krolik, J. H.; Meiksin, A.; Joss, P. C.

    1984-01-01

    A highly compact binary represents a system which is composed of a collapsed object (degenerate dwarf, neutron star, or black hole) in orbit with a low-mass (equal to or less than 0.5 solar mass) secondary star. Matter may be transferred from the secondary to the collapsed star due to the decay of the orbit resulting from the emission of gravitational radiation. The present investigation has the objective to study quantitatively the evolution of highly compact binaries in globular cluster cores, subject to the interplay of gravitational radiation and collisions with field stars. The investigation is exploratory in nature. The numerical methods employed are based on the techniques developed by Rappaport et al. (1982). It is found that occasional close encounters with field stars strongly dominate the evolution of highly compact binaries in dense globular cluster cores. Attention is given to the applicability of the findings to observations of X-ray sources and cataclysmic variables.

  20. Electron-Electron Interaction in Ion-Atom Collisions Studied by Projectile State-Resolved Auger Electron Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Lee, Do-Hyung

    1990-01-01

    This dissertation addresses the problem of dynamic electron-electron interactions in fast ion-atom collisions using projectile Auger electron spectroscopy. The study was carried out by measuring high-resolution projectile KLL Auger electron spectra as a function of projectile energy for the various collision systems of 0.25-2 MeV/u O^{q+} and F^ {q+} incident on H_2 and He targets. The electrons were detected in the beam direction, where the kinematic broadening is minimized. A zero-degree tandem electron spectrometer system was developed and showed the versatility of zero-degree measurements of collisionally-produced atomic states. The zero-degree binary encounter electrons (BEe), quasifree target electrons ionized by the projectiles in head-on collisions, were observed as a strong background in the KLL Auger electron spectrum. They were studied by treating the target ionization as 180^circ Rutherford elastic scattering in the projectile frame, and resulted in a validity test of the impulse approximation (IA) and a way to determine the spectrometer efficiency. An anomalous q-dependence, in which the zero-degree BEe yields increase with decreasing projectile charge state (q), was observed. State-resolved KLL Auger cross sections were determined by using the BEe normalization and thus the cross sections of the electron -electron interactions such as resonant transfer-excitation (RTE), electron-electron excitation (eeE), and electron -electron ionization (eeI) were determined. Projectile 2l capture with 1s to 2p excitation by the captured target electron was observed as an RTE process with Li-like and He-like projectiles and the measured RTEA (RTE followed by Auger decay) cross sections showed good agreement with an RTE-IA treatment and RTE alignment theory. Projectile 1s to 2p excitation by a target electron was observed an an eeE process with Li-like projectiles. Projectile 1s ionization by a target electron was observed as an eeI process with Be-like projectiles

  1. Evidence from d+Au measurements for final-state suppression of high-p(T) hadrons in Au+Au collisions at RHIC.

    PubMed

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-08-15

    We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions.

  2. J/ψ suppression at forward rapidity in Pb-Pb collisions at √s(NN) = 2.76 TeV.

    PubMed

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Scomparin, E; Scott, P A; Scott, R; Segato, G; Selyuzhenkov, I; Senyukov, S; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Sgura, I; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, N; Sharma, S; Shigaki, K; Shimomura, M; Shtejer, K; Sibiriak, Y; Siciliano, M; Sicking, E; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Sinha, T; Sinha, B C; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Son, H; Song, M; Song, J; Soos, C; Soramel, F; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stan, I; Stefanek, G; Stefanini, G; Steinbeck, T; Steinpreis, M; Stenlund, E; Steyn, G; Stocco, D; Stolpovskiy, M; Strabykin, K; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Sukhorukov, M; Sultanov, R; Sumbera, M; Susa, T; Szanto de Toledo, A; Szarka, I; Szostak, A; Tagridis, C; Takahashi, J; Tapia Takaki, J D; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Tlusty, D; Toia, A; Torii, H; Toscano, L; Tosello, F; Truesdale, D; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urbán, J; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vallero, S; van der Kolk, N; Vande Vyvre, P; van Leeuwen, M; Vannucci, L; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernekohl, D C; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Vikhlyantsev, O; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, Y; Vinogradov, L; Virgili, T; Viyogi, Y P; Vodopyanov, A; Voloshin, S; Voloshin, K; Volpe, G; von Haller, B; Vranic, D; Ovrebekk, G; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, B; Wagner, V; Wan, R; Wang, Y; Wang, D; Wang, Y; Wang, M; Watanabe, K; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, G; Wilk, A; Williams, M C S; Windelband, B; Xaplanteris Karampatsos, L; Yang, H; Yang, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yokoyama, H; Yoo, I-K; Yoon, J; Yu, W; Yuan, X; Yushmanov, I; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, X; Zhou, D; Zhou, Y; Zhou, F; Zhu, X; Zichichi, A; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M

    2012-08-17

    The ALICE experiment has measured the inclusive J/ψ production in Pb-Pb collisions at √s(NN) = 2.76 TeV down to zero transverse momentum in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/ψ yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%-80% most central collisions, is 0.545 ± 0.032(stat) ± 0.083(syst) and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/ψ production from charm quarks in a deconfined partonic phase can describe our data.

  3. Some Dynamic Characteristics of Binary Near-Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Ivanenko, N. V.; Bazyey, O. A.

    2017-02-01

    Tidal acceleration exerted by the terrestrial planets and Jupiter's are determined, orbital resonances to evaluate the motion stability in binary asteroid systems are calculated. Radius of the Hill sphere surrounding the main component in approximation of the planetary three-body problem - the Sun-main component-satellite is calculated. Escape velocities from the surface of the asteroid satellites are found and the conclusion on the possibility of substance loss is made.

  4. Approximate hard-sphere method for densely packed granular flows.

    PubMed

    Guttenberg, Nicholas

    2011-05-01

    The simulation of granular media is usually done either with event-driven codes that treat collisions as instantaneous but have difficulty with very dense packings, or with molecular dynamics (MD) methods that approximate rigid grains using a stiff viscoelastic spring. There is a little-known method that combines several collision events into a single timestep to retain the instantaneous collisions of event-driven dynamics, but also be able to handle dense packings. However, it is poorly characterized as to its regime of validity and failure modes. We present a modification of this method to reduce the introduction of overlap error, and test it using the problem of two-dimensional (2D) granular Couette flow, a densely packed system that has been well characterized by previous work. We find that this method can successfully replicate the results of previous work up to the point of jamming, and that it can do so a factor of 10 faster than comparable MD methods.

  5. Approximate hard-sphere method for densely packed granular flows

    NASA Astrophysics Data System (ADS)

    Guttenberg, Nicholas

    2011-05-01

    The simulation of granular media is usually done either with event-driven codes that treat collisions as instantaneous but have difficulty with very dense packings, or with molecular dynamics (MD) methods that approximate rigid grains using a stiff viscoelastic spring. There is a little-known method that combines several collision events into a single timestep to retain the instantaneous collisions of event-driven dynamics, but also be able to handle dense packings. However, it is poorly characterized as to its regime of validity and failure modes. We present a modification of this method to reduce the introduction of overlap error, and test it using the problem of two-dimensional (2D) granular Couette flow, a densely packed system that has been well characterized by previous work. We find that this method can successfully replicate the results of previous work up to the point of jamming, and that it can do so a factor of 10 faster than comparable MD methods.

  6. Vibrationally resolved charge transfer for proton collisions with CO and H collisions with CO{sup +}

    SciTech Connect

    Lin, C. Y.; Stancil, P. C.; Li, Y.; Gu, J. P.; Liebermann, H. P.; Buenker, R. J.; Kimura, M.

    2007-07-15

    Electron capture by protons following collisions with carbon monoxide, and the reverse process, is studied with a quantal molecular-orbital coupled-channel method utilizing the infinite order sudden approximation for collision energies between 0.5 and 1000 eV/u. The potential surfaces and couplings, computed with the multireference single- and double-excitation method for a range of H{sup +}-CO orientation angles and C-O separations, are adopted in the scattering calculations. Results including vibrationally resolved and orientation-angle-dependent cross sections are presented for a range of CO and CO{sup +} vibrational levels. Comparison with experiment is made where possible and the relevance of the reaction in astrophysics and atmospheric physics is discussed.

  7. Rational approximations for tomographic reconstructions

    NASA Astrophysics Data System (ADS)

    Reynolds, Matthew; Beylkin, Gregory; Monzón, Lucas

    2013-06-01

    We use optimal rational approximations of projection data collected in x-ray tomography to improve image resolution. Under the assumption that the object of interest is described by functions with jump discontinuities, for each projection we construct its rational approximation with a small (near optimal) number of terms for a given accuracy threshold. This allows us to augment the measured data, i.e., double the number of available samples in each projection or, equivalently, extend (double) the domain of their Fourier transform. We also develop a new, fast, polar coordinate Fourier domain algorithm which uses our nonlinear approximation of projection data in a natural way. Using augmented projections of the Shepp-Logan phantom, we provide a comparison between the new algorithm and the standard filtered back-projection algorithm. We demonstrate that the reconstructed image has improved resolution without additional artifacts near sharp transitions in the image.

  8. Gadgets, approximation, and linear programming

    SciTech Connect

    Trevisan, L.; Sudan, M.; Sorkin, G.B.; Williamson, D.P.

    1996-12-31

    We present a linear-programming based method for finding {open_quotes}gadgets{close_quotes}, i.e., combinatorial structures reducing constraints of one optimization problems to constraints of another. A key step in this method is a simple observation which limits the search space to a finite one. Using this new method we present a number of new, computer-constructed gadgets for several different reductions. This method also answers a question posed by on how to prove the optimality of gadgets-we show how LP duality gives such proofs. The new gadgets improve hardness results for MAX CUT and MAX DICUT, showing that approximating these problems to within factors of 60/61 and 44/45 respectively is N P-hard. We also use the gadgets to obtain an improved approximation algorithm for MAX 3SAT which guarantees an approximation ratio of .801. This improves upon the previous best bound of .7704.

  9. Learning Discriminative Binary Codes for Large-scale Cross-modal Retrieval.

    PubMed

    Xu, Xing; Shen, Fumin; Yang, Yang; Shen, Heng Tao; Li, Xuelong

    2017-05-01

    Hashing based methods have attracted considerable attention for efficient cross-modal retrieval on large-scale multimedia data. The core problem of cross-modal hashing is how to learn compact binary codes that construct the underlying correlations between heterogeneous features from different modalities. A majority of recent approaches aim at learning hash functions to preserve the pairwise similarities defined by given class labels. However, these methods fail to explicitly explore the discriminative property of class labels during hash function learning. In addition, they usually discard the discrete constraints imposed on the to-be-learned binary codes, and compromise to solve a relaxed problem with quantization to obtain the approximate binary solution. Therefore, the binary codes generated by these methods are suboptimal and less discriminative to different classes. To overcome these drawbacks, we propose a novel cross-modal hashing method, termed discrete cross-modal hashing (DCH), which directly learns discriminative binary codes while retaining the discrete constraints. Specifically, DCH learns modality-specific hash functions for generating unified binary codes, and these binary codes are viewed as representative features for discriminative classification with class labels. An effective discrete optimization algorithm is developed for DCH to jointly learn the modality-specific hash function and the unified binary codes. Extensive experiments on three benchmark data sets highlight the superiority of DCH under various cross-modal scenarios and show its state-of-the-art performance.

  10. The Michigan Binary Star Program

    NASA Astrophysics Data System (ADS)

    Lindner, Rudi P.

    2007-07-01

    At the end of the nineteenth century, William J. Hussey and Robert G. Aitken, both at Lick Observatory, began a systematic search for unrecorded binary stars with the aid of the 12" and 36" refracting telescopes at Lick Observatory. Aitken's work (and book on binary stars) are well known, Hussey's contributions less so. In 1905 Hussey, a Michigan engineering graduate, returned to direct the Ann Arbor astronomy program, and immediately he began to design new instrumentation for the study of binary stars and to train potential observers. For a time, he spent six months a year at the La Plata Observatory, where he discovered a number of new pairs and decided upon a major southern hemisphere campaign. He spent a decade obtaining the lenses for a large refractor, through the vicissitudes of war and depression. Finally, he obtained a site in South Africa, a 26" refractor, and a small corps of observers, but he died in London en route to fulfill his dream. His right hand man, Richard Rossiter, established the observatory and spent the next thirty years discovering and measuring binary stars: his personal total is a record for the field. This talk is an account of the methods, results, and utility of the extraordinary binary star factory in the veldt.

  11. Formation and Evolution of Planets in and Around Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Haghighipour, N.

    2015-07-01

    The discovery of planets in and around binary stars (also known as circumprimary and circumbinary planets) has opened a new chapter in the studies of the formation and dynamical evolution of planetary systems. Computational simulations indicate that in binaries with separations smaller than ˜50 au, the perturbation of the secondary star can have profound effects on the dynamics of solid bodies around the primary, prohibiting their collisions to result in coalescence and growth to larger objects. However, several circumprimary planets are known to exist in binaries with separations of ˜20 au raising questions about how these planets formed and acquired their final orbital architecture. Also, a survey of the currently known circumbinary planets (CBPs) points to several interesting characteristics of these bodies. The detection of multiple transits in these systems points to the (almost) co-planarity of the planet-binary orbits, giving strong support to the idea that these planets formed in circumbinary protoplanetary disks. The proximity of some of these planets to the boundary of orbital instability around the binary suggests an evolutionary scenario in which planets form at large distances and either migrate to their present orbits, or are scattered to their current locations. Surprisingly, all currently known CBPs are Neptune-sized or smaller, and no CBP seems to exist around very short-period binaries. These specific characteristics of binary-planetary systems have raised many questions regarding the formation, dynamical evolution, and orbital architecture of these objects. I will review the current state of research on the formation of planets in and around binary stars, and discuss the new developments on the understanding of their dynamical evolution.

  12. Soliton collisions in the discrete nonlinear Schrödinger equation.

    PubMed

    Papacharalampous, I E; Kevrekidis, P G; Malomed, B A; Frantzeskakis, D J

    2003-10-01

    We report analytical and numerical results for on-site and intersite collisions between solitons in the discrete nonlinear Schrödinger model. A semianalytical variational approximation correctly predicts gross features of the collision, viz., merger or bounce. We systematically examine the dependence of the collision outcome on initial velocity and amplitude of the solitons, as well as on the phase shift between them, and location of the collision point relative to the lattice; in some cases, the dependences are very intricate. In particular, merger of the solitons into a single one, and bounce after multiple collisions are found. Situations with a complicated system of alternating transmission and merger windows are identified too. The merger is often followed by symmetry breaking (SB), when the single soliton moves to the left or to the right, which implies momentum nonconservation. Two different types of the SB are identified, deterministic and spontaneous. The former one is accounted for by the location of the collision point relative to the lattice, and/or the phase shift between the solitons; the momentum generated during the collision due to the phase shift is calculated in an analytical approximation, its dependence on the solitons' velocities comparing well with numerical results. The spontaneous SB is explained by the modulational instability of a quasiflat plateau temporarily formed in the course of the collision.

  13. Evolution of Binary Supermassive Black Holes in Rotating Nuclei

    NASA Astrophysics Data System (ADS)

    Rasskazov, Alexander; Merritt, David

    2017-03-01

    The interaction of a binary supermassive black hole with stars in a galactic nucleus can result in changes to all the elements of the binary’s orbit, including the angles that define its orientation. If the nucleus is rotating, the orientation changes can be large, causing large changes in the binary’s orbital eccentricity as well. We present a general treatment of this problem based on the Fokker–Planck equation for f, defined as the probability distribution for the binary’s orbital elements. First- and second-order diffusion coefficients are derived for the orbital elements of the binary using numerical scattering experiments, and analytic approximations are presented for some of these coefficients. Solutions of the Fokker–Planck equation are then derived under various assumptions about the initial rotational state of the nucleus and the binary hardening rate. We find that the evolution of the orbital elements can become qualitatively different when we introduce nuclear rotation: (1) the orientation of the binary’s orbit evolves toward alignment with the plane of rotation of the nucleus and (2) binary orbital eccentricity decreases for aligned binaries and increases for counteraligned ones. We find that the diffusive (random-walk) component of a binary’s evolution is small in nuclei with non-negligible rotation, and we derive the time-evolution equations for the semimajor axis, eccentricity, and inclination in that approximation. The aforementioned effects could influence gravitational wave production as well as the relative orientation of host galaxies and radio jets.

  14. Adaptive approximation models in optimization

    SciTech Connect

    Voronin, A.N.

    1995-05-01

    The paper proposes a method for optimization of functions of several variables that substantially reduces the number of objective function evaluations compared to traditional methods. The method is based on the property of iterative refinement of approximation models of the optimand function in approximation domains that contract to the extremum point. It does not require subjective specification of the starting point, step length, or other parameters of the search procedure. The method is designed for efficient optimization of unimodal functions of several (not more than 10-15) variables and can be applied to find the global extremum of polymodal functions and also for optimization of scalarized forms of vector objective functions.

  15. Approximating spatially exclusive invasion processes

    NASA Astrophysics Data System (ADS)

    Ross, Joshua V.; Binder, Benjamin J.

    2014-05-01

    A number of biological processes, such as invasive plant species and cell migration, are composed of two key mechanisms: motility and reproduction. Due to the spatially exclusive interacting behavior of these processes a cellular automata (CA) model is specified to simulate a one-dimensional invasion process. Three (independence, Poisson, and 2D-Markov chain) approximations are considered that attempt to capture the average behavior of the CA. We show that our 2D-Markov chain approximation accurately predicts the state of the CA for a wide range of motility and reproduction rates.

  16. Heat pipe transient response approximation.

    SciTech Connect

    Reid, R. S.

    2001-01-01

    A simple and concise routine that approximates the response of an alkali metal heat pipe to changes in evaporator heat transfer rate is described. This analytically based routine is compared with data from a cylindrical heat pipe with a crescent-annular wick that undergoes gradual (quasi-steady) transitions through the viscous and condenser boundary heat transfer limits. The sonic heat transfer limit can also be incorporated into this routine for heat pipes with more closely coupled condensers. The advantages and obvious limitations of this approach are discussed. For reference, a source code listing for the approximation appears at the end of this paper.

  17. Second Approximation to Conical Flows

    DTIC Science & Technology

    1950-12-01

    Public Release WRIGHT AIR DEVELOPMENT CENTER AF-WP-(B)-O-29 JUL 53 100 NOTICES ’When Government drawings, specifications, or other data are used V...so that the X, the approximation always depends on the ( "/)th, etc. Here the second approximation, i.e., the terms in C and 62, are computed and...the scheme shown in Fig. 1, the isentropic equations of motion are (cV-X2) +~X~C 6 +- 4= -x- 1 It is assumed that + Ux !E . $O’/ + (8) Introducing Eqs

  18. Observing Massive Black Hole Binary Coalescences with LISA

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2005-01-01

    Massive black hole binary coalescences are among the most important astrophysical sources of gravitational waves to be observed by LISA. The ability to observe and characterize such sources with masses approximately equal to 105 M/odot and larger at high redshifts is strongly dependent on the sensitivity of LISA in the low frequency (0.1 mHz and below) regime. We examine LISA's ability to observe these systems at redshifts up to z approximately equal to 10 for various proposed values of the low frequency sensitivity, under current assumptions about the merger rates. The discussion will focus on the astrophysical information that can be gained by these observations.

  19. 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

  20. Observation of the emission of positive and negative ions in triple and quadruple collisions in a solid under bombardment with keV argon ions

    NASA Astrophysics Data System (ADS)

    Babenko, P. Yu.; Shergin, A. P.

    2006-12-01

    Particles that leave a solid as a result of several consecutive binary collisions are detected in the energy spectra of positive and negative ions emitted upon the irradiation of C, Si, Ge, and In targets with 2-to 5-keV Ar+ ions. The appearance of a spectral structure due to the sequence of three and four collisions in the solid can be attributed to the selective role of the surface, which is similar to the channeling effect in crystals.

  1. First-principles binary diffusion coefficients for H, H2 and four normal alkanes + N2

    SciTech Connect

    Jasper, Ahren W.; Kamarchik, Eugene; Miller, James A.; Klippenstein, Stephen J.

    2014-09-30

    Collision integrals related to binary (dilute gas) diffusion are calculated classically for six species colliding with N2. The most detailed calculations make no assumptions regarding the complexity of the potential energy surface, and the resulting classical collision integrals are in excellent agreement with previous semiclassical results for H + N2 and H2 + N2 and with recent experimental results for C n H2n+2 + N2, n = 2–4. The detailed classical results are used to test the accuracy of three simplifying assumptions typically made when calculating collision integrals: (1) approximating the intermolecular potential as isotropic, (2) neglecting the internal structure of the colliders (i.e., neglecting inelasticity), and (3) employing unphysical R–12 repulsive interactions. The effect of anisotropy is found to be negligible for H + N2 and H2 + N2 (in agreement with previous quantum mechanical and semiclassical results for systems involving atomic and diatomic species) but is more significant for larger species at low temperatures. For example, the neglect of anisotropy decreases the diffusion coefficient for butane + N2 by 15% at 300 K. The neglect of inelasticity, in contrast, introduces only very small errors. Approximating the repulsive wall as an unphysical R–12 interaction is a significant source of error at all temperatures for the weakly interacting systems H + N2 and H2 + N2, with errors as large as 40%. For the normal alkanes in N2, which feature stronger interactions, the 12/6 Lennard–Jones approximation is found to be accurate, particularly at temperatures above –700 K where it predicts the full-dimensional result to within 5% (although with somewhat different temperature dependence). Overall, the typical practical approach of assuming isotropic 12/6 Lennard

  2. Experience with parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.

    1993-01-01

    Parametric Binary Dissection (PBD) is a new algorithm that can be used for partitioning graphs embedded in 2- or 3-dimensional space. It partitions explicitly on the basis of nodes + (lambda)x(edges cut), where lambda is the ratio of time to communicate over an edge to the time to compute at a node. The new algorithm is faster than the original binary dissection algorithm and attempts to obtain better partitions than the older algorithm, which only takes nodes into account. The performance of parametric dissection with plain binary dissection on 3 large unstructured 3-d meshes obtained from computational fluid dynamics and on 2 random graphs were compared. It was showm that the new algorithm can usually yield partitions that are substantially superior, but that its performance is heavily dependent on the input data.

  3. Post-Newtonian approximation in Maxwell-like form

    SciTech Connect

    Kaplan, Jeffrey D.; Nichols, David A.; Thorne, Kip S.

    2009-12-15

    The equations of the linearized first post-Newtonian approximation to general relativity are often written in 'gravitoelectromagnetic' Maxwell-like form, since that facilitates physical intuition. Damour, Soffel, and Xu (DSX) (as a side issue in their complex but elegant papers on relativistic celestial mechanics) have expressed the first post-Newtonian approximation, including all nonlinearities, in Maxwell-like form. This paper summarizes that DSX Maxwell-like formalism (which is not easily extracted from their celestial mechanics papers), and then extends it to include the post-Newtonian (Landau-Lifshitz-based) gravitational momentum density, momentum flux (i.e. gravitational stress tensor), and law of momentum conservation in Maxwell-like form. The authors and their colleagues have found these Maxwell-like momentum tools useful for developing physical intuition into numerical-relativity simulations of compact binaries with spin.

  4. Pythagorean Approximations and Continued Fractions

    ERIC Educational Resources Information Center

    Peralta, Javier

    2008-01-01

    In this article, we will show that the Pythagorean approximations of [the square root of] 2 coincide with those achieved in the 16th century by means of continued fractions. Assuming this fact and the known relation that connects the Fibonacci sequence with the golden section, we shall establish a procedure to obtain sequences of rational numbers…

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Effect of collisions on photoelectron sheath in a gas

    NASA Astrophysics Data System (ADS)

    Sodha, Mahendra Singh; Mishra, S. K.

    2016-02-01

    This paper presents a study of the effect of the collision of electrons with atoms/molecules on the structure of a photoelectron sheath. Considering the half Fermi-Dirac distribution of photo-emitted electrons, an expression for the electron density in the sheath has been derived in terms of the electric potential and the structure of the sheath has been investigated by incorporating Poisson's equation in the analysis. The method of successive approximations has been used to solve Poisson's equation with the solution for the electric potential in the case of vacuum, obtained earlier [Sodha and Mishra, Phys. Plasmas 21, 093704 (2014)], being used as the zeroth order solution for the present analysis. The inclusion of collisions influences the photoelectron sheath structure significantly; a reduction in the sheath width with increasing collisions is obtained.

  10. Protocols for quantum binary voting

    NASA Astrophysics Data System (ADS)

    Thapliyal, Kishore; Sharma, Rishi Dutt; Pathak, Anirban

    Two new protocols for quantum binary voting are proposed. One of the proposed protocols is designed using a standard scheme for controlled deterministic secure quantum communication (CDSQC), and the other one is designed using the idea of quantum cryptographic switch, which uses a technique known as permutation of particles. A few possible alternative approaches to accomplish the same task (quantum binary voting) have also been discussed. Security of the proposed protocols is analyzed. Further, the efficiencies of the proposed protocols are computed, and are compared with that of the existing protocols. The comparison has established that the proposed protocols are more efficient than the existing protocols.

  11. Mental Effort in Binary Categorization Aided by Binary Cues

    ERIC Educational Resources Information Center

    Botzer, Assaf; Meyer, Joachim; Parmet, Yisrael

    2013-01-01

    Binary cueing systems assist in many tasks, often alerting people about potential hazards (such as alarms and alerts). We investigate whether cues, besides possibly improving decision accuracy, also affect the effort users invest in tasks and whether the required effort in tasks affects the responses to cues. We developed a novel experimental tool…

  12. 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

  13. A Detection Pipeline for Galactic Binaries in LISA Data

    NASA Technical Reports Server (NTRS)

    Littenberg, Tyson B.

    2012-01-01

    The Galaxy is suspected to contain hundreds of millions of binary white dwarf systems, a large fraction of which will have sufficiently small orbital period to emit gravitational radiation in band for space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA). LISA's main science goal is the detection of cosmological events (supermassive black hole mergers) etc.) however the gravitational signal from the galaxy will be the dominant contribution to the data - including instrumental noise - over approximately two decades in frequency. The catalogue of detectable binary systems will serve as an unparalleled means of studying the Galaxy. Furthermore, to maximize the scientific return from the mission, the data must be "cleansed" of the galactic foreground. We will present an algorithm that can accurately resolve and subtract greater than or equal to 10000 of these sources from simulated data supplied by the Mock LISA Data Challenge Task Force. Using the time evolution of the gravitational wave frequency, we will reconstruct the position of the recovered binaries and show how LISA will sample the entire compact binary population in the Galaxy.

  14. Segregation of Fluidized Binary Hard-Sphere Systems Under Gravity

    NASA Astrophysics Data System (ADS)

    Kim, Soon-Chul

    We have derived an analytic expression for the contact value of the local density of binary hard-sphere systems under gravity. We have obtained the crossover conditions for the Brazil-nut type segregation of binary hard-sphere mixtures and binary hard-sphere chain mixtures from the segregation criterion, where the segregation occurs when the density (or the pressure) of the small spheres at the bottom is higher than that of the large spheres, or vice versa. For the binary hard-sphere chain mixtures, the crossover condition for the segregation depends on the number of monomers composed of hard-sphere chains as well as the mass and the diameter of each species. The fundamental-measure theories (FMTs) and local density approximation (LDA) are employed to examine the crossover condition for the segregation of the gravity-induced hard-sphere mixtures. The calculated results show that the LDA does not explain the density oscillation near the bottom, whereas the modified fundamental-measure theory (MFMT) compares with molecular dynamics simulations.

  15. The Relativitic Evolution of Black Hole-Neutron Star Binaries

    NASA Astrophysics Data System (ADS)

    Faber, J. A.; Baumgarte, T. W.; Shapiro, S. L.; Taniguchi, K.

    2004-12-01

    We report results from our new relativistic evolution calculations of black hole-neutron star (BH-NS) binaries. The evolution equations of general relativity are treated in the conformally flat (CF) approximation. Assuming that the BH mass is significantly larger than that of the NS allows us to simplify the field equations for the NS, which we solve self-consistently in a fixed BH background spacetime. This approach guarantees that self-gravity is fully included. The NS fluid, assumed here to follow a gamma-law equation of state (EOS), is evolved using a Lagrangian SPH method. The field equations are solved by spectral methods in spheroidal coordinates. The code has been tested by comparing our results to previously computed quasi-equilibrium sequences, showing good agreement. Our results are a crucial first step in evaluating the stability of mass transfer in extremely close BH-NS binaries. They will allow us to describe quantitatively the dynamical tidal disruption of the NS, and to determine the dependence on the initial binary parameters, including the mass ratio and assumed NS EOS. We will also discuss the implications for detecting gravitational waves from the merger of these systems, about which, in contrast to NS-NS binaries, little is currently known for systems with components of comparable mass. JAF is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0401533.

  16. Determination of the Period of Binary Asteroid Systems

    NASA Astrophysics Data System (ADS)

    Lust, Nathaniel B.; Britt, D. T.

    2008-09-01

    In the study of asteroids, binary pairs offer a unique window of study. By observing these systems and determining the period of the secondary, it is possible to determine system mass (e.g. Pravec and Hahn 1997; Ryan et al., 2004). With mass and volume, properties such as bulk density and porosity can be derived. At the University of Central Florida we have begun a binary asteroid hunt, in conjunction with the Prague consortium, in order to identify new binary candidates and to better constrain data on known pairs. All of the observations are collected on campus using a 0.5meter f/8.1 Ritchey-Chretien telescope with a SBIG STL-6303E detector. For our first test target we observed the known binary asteroid 107 Camila over a period of six days for approximately six to eight hours a night. The data is then processed using an open source python algorithm developed by Nate Lust. The data is read in, reduced, and compared to a standard star. Once the light curve was generated we make use of the CLEAN algorithm, originally developed by Hogbom (1974), to extract meaningful periods from the light curve.

  17. BINARY YORP EFFECT AND EVOLUTION OF BINARY ASTEROIDS

    SciTech Connect

    Steinberg, Elad; Sari, Re'em

    2011-02-15

    The rotation states of kilometer-sized near-Earth asteroids are known to be affected by the Yarkevsky O'Keefe-Radzievskii-Paddack (YORP) effect. In a related effect, binary YORP (BYORP), the orbital properties of a binary asteroid evolve under a radiation effect mostly acting on a tidally locked secondary. The BYORP effect can alter the orbital elements over {approx}10{sup 4}-10{sup 5} years for a D{sub p} = 2 km primary with a D{sub s} = 0.4 km secondary at 1 AU. It can either separate the binary components or cause them to collide. In this paper, we devise a simple approach to calculate the YORP effect on asteroids and the BYORP effect on binaries including J{sub 2} effects due to primary oblateness and the Sun. We apply this to asteroids with known shapes as well as a set of randomly generated bodies with various degrees of smoothness. We find a strong correlation between the strengths of an asteroid's YORP and BYORP effects. Therefore, statistical knowledge of one could be used to estimate the effect of the other. We show that the action of BYORP preferentially shrinks rather than expands the binary orbit and that YORP preferentially slows down asteroids. This conclusion holds for the two extremes of thermal conductivities studied in this work and the assumption that the asteroid reaches a stable point, but may break down for moderate thermal conductivity. The YORP and BYORP effects are shown to be smaller than could be naively expected due to near cancellation of the effects at small scales. Taking this near cancellation into account, a simple order-of-magnitude estimate of the YORP and BYORP effects as a function of the sizes and smoothness of the bodies is calculated. Finally, we provide a simple proof showing that there is no secular effect due to absorption of radiation in BYORP.

  18. KEPLER ECLIPSING BINARIES WITH STELLAR COMPANIONS

    SciTech Connect

    Gies, D. R.; Matson, R. A.; Guo, Z.; Lester, K. V.; Orosz, J. A.; Peters, G. J. E-mail: rmatson@chara.gsu.edu E-mail: lester@chara.gsu.edu E-mail: gjpeters@mucen.usc.edu

    2015-12-15

    Many short-period binary stars have distant orbiting companions that have played a role in driving the binary components into close separation. Indirect detection of a tertiary star is possible by measuring apparent changes in eclipse times of eclipsing binaries as the binary orbits the common center of mass. Here we present an analysis of the eclipse timings of 41 eclipsing binaries observed throughout the NASA Kepler mission of long duration and precise photometry. This subset of binaries is characterized by relatively deep and frequent eclipses of both stellar components. We present preliminary orbital elements for seven probable triple stars among this sample, and we discuss apparent period changes in seven additional eclipsing binaries that may be related to motion about a tertiary in a long period orbit. The results will be used in ongoing investigations of the spectra and light curves of these binaries for further evidence of the presence of third stars.

  19. Study of bottleneck effect at an emergency evacuation exit using cellular automata model, mean field approximation analysis, and game theory

    NASA Astrophysics Data System (ADS)

    Tanimoto, Jun; Hagishima, Aya; Tanaka, Yasukaka

    2010-12-01

    An improved cellular automaton model for pedestrian dynamics was established, where both static floor field and collision effect derived from game theory were considered. Several model parameters were carefully determined by previous studies. Results obtained through model-based simulation and analytical approach (derived from mean field approximation) proved that outflow rate from an evacuation exit, which is usually estimated using outflow coefficient in building codes in Japan, can be improved by placing an appropriate obstacle in front of the exit. This can reduce collision probability at the exit by increasing collisions around the obstacles ahead of the exit.

  20. Testing the frozen flow approximation

    NASA Technical Reports Server (NTRS)

    Lucchin, Francesco; Matarrese, Sabino; Melott, Adrian L.; Moscardini, Lauro

    1993-01-01

    We investigate the accuracy of the frozen-flow approximation (FFA), recently proposed by Matarrese, et al. (1992), for following the nonlinear evolution of cosmological density fluctuations under gravitational instability. We compare a number of statistics between results of the FFA and n-body simulations, including those used by Melott, Pellman & Shandarin (1993) to test the Zel'dovich approximation. The FFA performs reasonably well in a statistical sense, e.g. in reproducing the counts-in-cell distribution, at small scales, but it does poorly in the crosscorrelation with n-body which means it is generally not moving mass to the right place, especially in models with high small-scale power.

  1. Ab initio dynamical vertex approximation

    NASA Astrophysics Data System (ADS)

    Galler, Anna; Thunström, Patrik; Gunacker, Patrik; Tomczak, Jan M.; Held, Karsten

    2017-03-01

    Diagrammatic extensions of dynamical mean-field theory (DMFT) such as the dynamical vertex approximation (DΓ A) allow us to include nonlocal correlations beyond DMFT on all length scales and proved their worth for model calculations. Here, we develop and implement an Ab initio DΓ A approach (AbinitioDΓ A ) for electronic structure calculations of materials. The starting point is the two-particle irreducible vertex in the two particle-hole channels which is approximated by the bare nonlocal Coulomb interaction and all local vertex corrections. From this, we calculate the full nonlocal vertex and the nonlocal self-energy through the Bethe-Salpeter equation. The AbinitioDΓ A approach naturally generates all local DMFT correlations and all nonlocal G W contributions, but also further nonlocal correlations beyond: mixed terms of the former two and nonlocal spin fluctuations. We apply this new methodology to the prototypical correlated metal SrVO3.

  2. Potential of the approximation method

    SciTech Connect

    Amano, K.; Maruoka, A.

    1996-12-31

    Developing some techniques for the approximation method, we establish precise versions of the following statements concerning lower bounds for circuits that detect cliques of size s in a graph with m vertices: For 5 {le} s {le} m/4, a monotone circuit computing CLIQUE(m, s) contains at least (1/2)1.8{sup min}({radical}s-1/2,m/(4s)) gates: If a non-monotone circuit computes CLIQUE using a {open_quotes}small{close_quotes} amount of negation, then the circuit contains an exponential number of gates. The former is proved very simply using so called bottleneck counting argument within the framework of approximation, whereas the latter is verified introducing a notion of restricting negation and generalizing the sunflower contraction.

  3. On some electrodynamic properties of binary pulsars

    NASA Astrophysics Data System (ADS)

    Sironi, Lorenzo

    2006-07-01

    The main purpose of my thesis is to examine some electrodynamic properties of binary pulsars, trying to understand the peculiar physical processes that can happen in their magnetospheres; the ultimate aim is to discuss if such systems can be the source of the observed flux of cosmic rays between the knee and the ankle, since the mechanisms of acceleration for the cosmic rays in this range of energies are still unknown. Attention around binary pulsars has arisen after the recent discovery (December 2003) of the first double neutron star system in which both the stars are visible as pulsars (PSR J0737-3039); the inspection of the physical features of this binary pulsar has led to some intriguing possibilities up to now unexplored. In this thesis I will first of all review what is already known about the main properties of this binary system. I will describe in particular the possibility to go further in the verification of the predictions of general relativity with the so-called post-Keplerian parameters; I will discuss the possibility of studying the optical properties of the magnetospheres, since the inclination angle of the orbit is nearly 90° and some orbital phases show an eclipse of the light from one pulsar due to absorption by the magnetosphere of the companion; I will rapidly summarize how the discovery of that binary pulsar can enlarge our knowledge about the origin and evolution of double neutron star systems; lastly, I will examine the increase in the estimate of the Galactic double neutron star merger rate due to the discovery of PSR J0737-3039. I will then summarize the current knowledge about the magnetosphere of a single pulsar. After describing the Gold-Pacini model for the energy loss of the oblique rotator (in which the magnetic and rotational axes are not parallel), I will discuss the Goldreich-Julian model for the aligned axisymmetric rotator in the force-free approximation in which the inertial and gravitational forces are neglected with

  4. Nonlinear Filtering and Approximation Techniques

    DTIC Science & Technology

    1991-09-01

    Shwartz), Academic Press (1991). [191 M.Cl. ROUTBAUD, Fiting lindairc par morceaux avec petit bruit d’obserration, These. Universit6 de Provence ( 1990...Kernel System (GKS), Academic Press (1983). 181 H.J. KUSHNER, Probability methods for approximations in stochastic control and for elliptic equations... Academic Press (1977). [9] F. LE GLAND, Time discretization of nonlinear filtering equations, in: 28th. IEEE CDC, Tampa, pp. 2601-2606. IEEE Press (1989

  5. Reliable Function Approximation and Estimation

    DTIC Science & Technology

    2016-08-16

    Journal on Mathematical Analysis 47 (6), 2015. 4606-4629. (P3) The Sample Complexity of Weighted Sparse Approximation. B. Bah and R. Ward. IEEE...solving systems of quadratic equations. S. Sanghavi, C. White, and R. Ward. Results in Mathematics , 2016. (O5) Relax, no need to round: Integrality of...Theoretical Computer Science. (O6) A unified framework for linear dimensionality reduction in L1. F Krahmer and R Ward. Results in Mathematics , 2014. 1-23

  6. 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.

  7. Approximate Counting of Graphical Realizations.

    PubMed

    Erdős, Péter L; Kiss, Sándor Z; Miklós, István; Soukup, Lajos

    2015-01-01

    In 1999 Kannan, Tetali and Vempala proposed a MCMC method to uniformly sample all possible realizations of a given graphical degree sequence and conjectured its rapidly mixing nature. Recently their conjecture was proved affirmative for regular graphs (by Cooper, Dyer and Greenhill, 2007), for regular directed graphs (by Greenhill, 2011) and for half-regular bipartite graphs (by Miklós, Erdős and Soukup, 2013). Several heuristics on counting the number of possible realizations exist (via sampling processes), and while they work well in practice, so far no approximation guarantees exist for such an approach. This paper is the first to develop a method for counting realizations with provable approximation guarantee. In fact, we solve a slightly more general problem; besides the graphical degree sequence a small set of forbidden edges is also given. We show that for the general problem (which contains the Greenhill problem and the Miklós, Erdős and Soukup problem as special cases) the derived MCMC process is rapidly mixing. Further, we show that this new problem is self-reducible therefore it provides a fully polynomial randomized approximation scheme (a.k.a. FPRAS) for counting of all realizations.

  8. Approximate Counting of Graphical Realizations

    PubMed Central

    2015-01-01

    In 1999 Kannan, Tetali and Vempala proposed a MCMC method to uniformly sample all possible realizations of a given graphical degree sequence and conjectured its rapidly mixing nature. Recently their conjecture was proved affirmative for regular graphs (by Cooper, Dyer and Greenhill, 2007), for regular directed graphs (by Greenhill, 2011) and for half-regular bipartite graphs (by Miklós, Erdős and Soukup, 2013). Several heuristics on counting the number of possible realizations exist (via sampling processes), and while they work well in practice, so far no approximation guarantees exist for such an approach. This paper is the first to develop a method for counting realizations with provable approximation guarantee. In fact, we solve a slightly more general problem; besides the graphical degree sequence a small set of forbidden edges is also given. We show that for the general problem (which contains the Greenhill problem and the Miklós, Erdős and Soukup problem as special cases) the derived MCMC process is rapidly mixing. Further, we show that this new problem is self-reducible therefore it provides a fully polynomial randomized approximation scheme (a.k.a. FPRAS) for counting of all realizations. PMID:26161994

  9. Computer Experiments for Function Approximations

    SciTech Connect

    Chang, A; Izmailov, I; Rizzo, S; Wynter, S; Alexandrov, O; Tong, C

    2007-10-15

    This research project falls in the domain of response surface methodology, which seeks cost-effective ways to accurately fit an approximate function to experimental data. Modeling and computer simulation are essential tools in modern science and engineering. A computer simulation can be viewed as a function that receives input from a given parameter space and produces an output. Running the simulation repeatedly amounts to an equivalent number of function evaluations, and for complex models, such function evaluations can be very time-consuming. It is then of paramount importance to intelligently choose a relatively small set of sample points in the parameter space at which to evaluate the given function, and then use this information to construct a surrogate function that is close to the original function and takes little time to evaluate. This study was divided into two parts. The first part consisted of comparing four sampling methods and two function approximation methods in terms of efficiency and accuracy for simple test functions. The sampling methods used were Monte Carlo, Quasi-Random LP{sub {tau}}, Maximin Latin Hypercubes, and Orthogonal-Array-Based Latin Hypercubes. The function approximation methods utilized were Multivariate Adaptive Regression Splines (MARS) and Support Vector Machines (SVM). The second part of the study concerned adaptive sampling methods with a focus on creating useful sets of sample points specifically for monotonic functions, functions with a single minimum and functions with a bounded first derivative.

  10. Approximate reasoning using terminological models

    NASA Technical Reports Server (NTRS)

    Yen, John; Vaidya, Nitin

    1992-01-01

    Term Subsumption Systems (TSS) form a knowledge-representation scheme in AI that can express the defining characteristics of concepts through a formal language that has a well-defined semantics and incorporates a reasoning mechanism that can deduce whether one concept subsumes another. However, TSS's have very limited ability to deal with the issue of uncertainty in knowledge bases. The objective of this research is to address issues in combining approximate reasoning with term subsumption systems. To do this, we have extended an existing AI architecture (CLASP) that is built on the top of a term subsumption system (LOOM). First, the assertional component of LOOM has been extended for asserting and representing uncertain propositions. Second, we have extended the pattern matcher of CLASP for plausible rule-based inferences. Third, an approximate reasoning model has been added to facilitate various kinds of approximate reasoning. And finally, the issue of inconsistency in truth values due to inheritance is addressed using justification of those values. This architecture enhances the reasoning capabilities of expert systems by providing support for reasoning under uncertainty using knowledge captured in TSS. Also, as definitional knowledge is explicit and separate from heuristic knowledge for plausible inferences, the maintainability of expert systems could be improved.

  11. Recommended direct simulation Monte Carlo collision model parameters for modeling ionized air transport processes

    SciTech Connect

    Swaminathan-Gopalan, Krishnan; Stephani, Kelly A.

    2016-02-15

    A systematic approach for calibrating the direct simulation Monte Carlo (DSMC) collision model parameters to achieve consistency in the transport processes is presented. The DSMC collision cross section model parameters are calibrated for high temperature atmospheric conditions by matching the collision integrals from DSMC against ab initio based collision integrals that are currently employed in the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) and Data Parallel Line Relaxation (DPLR) high temperature computational fluid dynamics solvers. The DSMC parameter values are computed for the widely used Variable Hard Sphere (VHS) and the Variable Soft Sphere (VSS) models using the collision-specific pairing approach. The recommended best-fit VHS/VSS parameter values are provided over a temperature range of 1000-20 000 K for a thirteen-species ionized air mixture. Use of the VSS model is necessary to achieve consistency in transport processes of ionized gases. The agreement of the VSS model transport properties with the transport properties as determined by the ab initio collision integral fits was found to be within 6% in the entire temperature range, regardless of the composition of the mixture. The recommended model parameter values can be readily applied to any gas mixture involving binary collisional interactions between the chemical species presented for the specified temperature range.

  12. W and Z bosons with CMS in pp, pPb and PbPb collisions

    NASA Astrophysics Data System (ADS)

    Chapon, Émilien

    2016-12-01

    Electroweak boson production is an important benchmark process in high-energy heavy-ion collisions at the LHC. W and Z bosons do not participate in the strong interaction and their leptonic decays provide medium-blind probes of the initial state of the collisions. The final results on the W and Z production in pPb collisions at 5.02 TeV, combining both the muon and electron channels, will be presented. When compared to theory calculations that include nuclear modifications to the parton distributions, data show a clear sensitivity to this type of effects. The final results in PbPb collisions at 2.76 TeV, compared to pp collisions at the same centre of mass energy, will also be presented. The centrality dependence confirms the binary scaling of hard probes in heavy-ion collisions, while the differential cross sections points to initial state effects small compared to the statistical precision of the available data.

  13. Generating Constant Weight Binary Codes

    ERIC Educational Resources Information Center

    Knight, D.G.

    2008-01-01

    The determination of bounds for A(n, d, w), the maximum possible number of binary vectors of length n, weight w, and pairwise Hamming distance no less than d, is a classic problem in coding theory. Such sets of vectors have many applications. A description is given of how the problem can be used in a first-year undergraduate computational…

  14. Binary logic is rich enough

    SciTech Connect

    Zapatrin, R.R.

    1992-02-01

    Given a finite ortholattice L, the *-semigroup is explicitly built whose annihilator ortholattice is isomorphic to L. Thus, it is shown that any finite quantum logic is the additive part of a binary logic. Some areas of possible applications are outlined. 7 refs.

  15. The Outcome of Supernovae in Massive Binaries; Removed Mass, and its Separation Dependence

    NASA Astrophysics Data System (ADS)

    Hirai, Ryosuke; Sawai, Hidetomo; Yamada, Shoichi

    2014-09-01

    The majority of massive stars are formed in binary systems. It is hence reasonable to expect that most core-collapse supernovae (CCSNe) take place in binaries and the existence of a companion star may leave some imprints in observed features. Having this in mind, we have conducted two-dimensional hydrodynamical simulations of the collisions of CCSNe ejecta with the companion star in an almost-equal-mass (~10 M ⊙) binary to find out possible consequences of such events. In particular we pay attention to the amount of mass removed and its dependence on the binary separation. In contrast to the previous surmise, we find that the companion mass is stripped not by momentum transfer but by shock heating. Up to 25% of the original mass can be removed for the closest separations and the removed mass decreases as M ubvpropa -4.3 with the binary separation a. By performing some experimental computations with artificially modified densities of incident ejecta, we show that if the velocity of ejecta is fixed, the density of incident ejecta is the single important parameter that actually determines the removed mass as Mub \\propto ρ ej 1.4. On the other hand, another set of simulations with modified velocities of incident ejecta demonstrate that the strength of the forward shock, which heats up the stellar material and causes the mass loss of the companion star, is actually the key parameter for the removed mass.

  16. Light assisted collisions in ultra cold Tm atom

    NASA Astrophysics Data System (ADS)

    Akimov, Alexey; Cojocaru, Ivan; Pyatchenkov, Sergey; Snigirev, Stepan; Luchnokov, Ilia; Sukachev, Denis; Kalganova, Elena; Sorokin, Vadim

    2016-05-01

    Recently laser cooled rare earth elements attracted considerable attention due to the high orbital and magnetic moments. Such a systems allow low-field Feshabach resonances enabling tunable in wide range interactions. In particular, thulium atom has one hole in 4f shell therefore having orbital moment of 3 in the ground state, magnetic moment of 4 Bohr magnetons in ground state. While magnetic moment of the thulium atom is less than that of Erbium or Dysprosium simpler level structure, possibility to capture thulium atoms and the dipole trap at 532 nm make thulium atom an extremely attractive subject for quantum simulations. Nevertheless collisional properties of thulium atom are not yet explored in details, in particular light assisted collision of thulium atom were not yet investigated. In this contribution, we performed studies of light assisted collisions near in Magneto optical trap operating on narrow 530.7 nm transition. We found, that light assisted inelastic binary collisions losses rate is around β ~10-9cm3cm3s s . Possible mechanism of losses from the trap are discussed

  17. The effect of inelastic collisions on the transport of alpha particles in ITER-like plasmas

    NASA Astrophysics Data System (ADS)

    Clauser, C. F.; Farengo, R.

    2017-04-01

    The effect of charge changes on the transport of alpha particles in ITER-like plasmas is studied with a numerical code that follows the exact particle trajectories and includes the effect of elastic and inelastic collisions. It is shown that charge changing processes can produce significant changes in the transport of alpha particles in the edge-SOL region. The addition of inelastic collisions actually reduces the alpha particle loss rate below the level obtained when only elastic (Coulomb) collisions are included. This is due to the inward flux produced by the neutral density gradient. Power losses, on the other hand, remain at approximately the same level because the average energy of the lost particles is higher when inelastic collisions are included. Finally, the spatial distribution of the lost particles changes significantly when inelastic collisions are added, with a larger fraction of the lost particles reaching the wall.

  18. A deterministic-stochastic approach to compute the Boltzmann collision integral in O(MN) operations

    NASA Astrophysics Data System (ADS)

    Alekseenko, Alexander; Nguyen, Truong; Wood, Aihua

    2016-11-01

    We developed and implemented a numerical algorithm for evaluating the Boltzmann collision operator with O(MN) operations, where N is the number of the discrete velocity points and M < N. The approach is formulated using a bilinear convolution form of the Galerkin projection of the collision operator and discontinuous Galerkin (DG) discretizations of the collision operator. Key ingredients of the new approach are singular value decomposition (SVD) compression of the collision kernel and approximations of the solution by a sum of Maxwellian streams using a stochastic likelihood maximization algorithm. The developed method is significantly faster than the full deterministic DG velocity discretization of the collision integral. Accuracy of the method is established on solutions to the problem of spatially homogeneous relaxation.

  19. Anisotropic mechanoresponse of energetic crystallites: a quantum molecular dynamics study of nano-collision

    NASA Astrophysics Data System (ADS)

    Li, Ying; Kalia, Rajiv K.; Misawa, Masaaki; Nakano, Aiichiro; Nomura, Ken-Ichi; Shimamura, Kohei; Shimojo, Fuyuki; Vashishta, Priya

    2016-05-01

    At the nanoscale, chemistry can happen quite differently due to mechanical forces selectively breaking the chemical bonds of materials. The interaction between chemistry and mechanical forces can be classified as mechanochemistry. An example of archetypal mechanochemistry occurs at the nanoscale in anisotropic detonating of a broad class of layered energetic molecular crystals bonded by inter-layer van der Waals (vdW) interactions. Here, we introduce an ab initio study of the collision, in which quantum molecular dynamic simulations of binary collisions between energetic vdW crystallites, TATB molecules, reveal atomistic mechanisms of anisotropic shock sensitivity. The highly sensitive lateral collision was found to originate from the twisting and bending to breaking of nitro-groups mediated by strong intra-layer hydrogen bonds. This causes the closing of the electronic energy gap due to an inverse Jahn-Teller effect. On the other hand, the insensitive collisions normal to multilayers are accomplished by more delocalized molecular deformations mediated by inter-layer interactions. Our nano-collision studies provide a much needed atomistic understanding for the rational design of insensitive energetic nanomaterials and the detonation synthesis of novel nanomaterials.At the nanoscale, chemistry can happen quite differently due to mechanical forces selectively breaking the chemical bonds of materials. The interaction between chemistry and mechanical forces can be classified as mechanochemistry. An example of archetypal mechanochemistry occurs at the nanoscale in anisotropic detonating of a broad class of layered energetic molecular crystals bonded by inter-layer van der Waals (vdW) interactions. Here, we introduce an ab initio study of the collision, in which quantum molecular dynamic simulations of binary collisions between energetic vdW crystallites, TATB molecules, reveal atomistic mechanisms of anisotropic shock sensitivity. The highly sensitive lateral collision

  20. Production of trans-Neptunian binaries through chaos-assisted capture

    NASA Astrophysics Data System (ADS)

    Lee, Ernestine A.; Astakhov, Sergey A.; Farrelly, David

    2007-07-01

    The recent discovery of binary objects in the Kuiper Belt opens an invaluable window into past and present conditions in the trans-Neptunian part of the Solar System. For example, knowledge of how these objects formed can be used to impose constraints on planetary formation theories. We have recently proposed a binary object formation model based on the notion of chaos-assisted capture (CAC). In this model two potential binary partners may become trapped for long times inside chaotic layers within their mutual Hill sphere. The binary may then be captured permanently through gravitational scattering with a third `intruder' body. The creation of binaries having similarly sized partners is an ab initio prediction of the model which also predicts large binary semimajor axes and moderately eccentric mutual orbits similar to those observed. Here we present a more detailed analysis with calculations performed in the spatial (three-dimensional) three- and four-body Hill approximations. It is assumed that the potential binary partners are initially following heliocentric Keplerian orbits and that their relative motion becomes perturbed as these objects undergo close encounters. First, the mass, velocity and orbital element distributions which favour binary formation are identified in the circular and elliptical Hill limits. We then consider intruder scattering to the circular Hill four-body problem and find that the CAC mechanism is consistent with observed, apparently randomly distributed, binary mutual orbit inclinations. It also predicts asymmetric distributions of retrograde versus prograde orbits. The time-delay induced by chaos on particle transport through the Hill sphere is analogous to the formation of a resonance in a chemical reaction. Implications for binary formation rates are considered and the `fine-tuning' problem recently identified by Noll et al. is also addressed.

  1. Coevolution of binaries and circumbinary gaseous discs

    NASA Astrophysics Data System (ADS)

    Fleming, David P.; Quinn, Thomas R.

    2017-01-01

    The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disc and how the disc and binary interact and change as a result. The central binary excites resonances in the surrounding protoplanetary disc which drive evolution in both the binary orbital elements and in the disc. To probe how these interactions impact binary eccentricity and disc structure evolution, N-body smooth particle hydrodynamics simulations of gaseous protoplanetary discs surrounding binaries based on Kepler 38 were run for 104 binary periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disc via a parametric instability and excite disc eccentricity growth. Eccentric binaries strongly couple to the disc causing eccentricity growth for both the disc and binary. Discs around sufficiently eccentric binaries which strongly couple to the disc develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance which corresponds to an alignment of gas particle longitude of periastrons. All systems display binary semimajor axis decay due to dissipation from the viscous disc.

  2. 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.

  3. A Novel Method of the Generalized Interval-Valued Fuzzy Rough Approximation Operators

    PubMed Central

    Xue, Tianyu; Xue, Zhan'ao; Cheng, Huiru; Liu, Jie; Zhu, Tailong

    2014-01-01

    Rough set theory is a suitable tool for dealing with the imprecision, uncertainty, incompleteness, and vagueness of knowledge. In this paper, new lower and upper approximation operators for generalized fuzzy rough sets are constructed, and their definitions are expanded to the interval-valued environment. Furthermore, the properties of this type of rough sets are analyzed. These operators are shown to be equivalent to the generalized interval fuzzy rough approximation operators introduced by Dubois, which are determined by any interval-valued fuzzy binary relation expressed in a generalized approximation space. Main properties of these operators are discussed under different interval-valued fuzzy binary relations, and the illustrative examples are given to demonstrate the main features of the proposed operators. PMID:25162065

  4. Refinements of universal approximation results for deep belief networks and restricted Boltzmann machines.

    PubMed

    Montufar, Guido; Ay, Nihat

    2011-05-01

    We improve recently published results about resources of restricted Boltzmann machines (RBM) and deep belief networks (DBN)required to make them universal approximators. We show that any distribution pon the set {0,1}(n) of binary vectors of length n can be arbitrarily well approximated by an RBM with k-1 hidden units, where k is the minimal number of pairs of binary vectors differing in only one entry such that their union contains the support set of p. In important cases this number is half the cardinality of the support set of p (given in Le Roux & Bengio, 2008). We construct a DBN with 2n/ 2(n-b) , b ∼ log n, hidden layers of width n that is capable of approximating any distribution on {0,1}(n) arbitrarily well. This confirms a conjecture presented in Le Roux and Bengio (2010).

  5. Simulating binary inspirals in a corotating spherical coordinate system

    NASA Astrophysics Data System (ADS)

    Garrett, Travis Marshall

    The gravitational waves produced by the inspiral and merger of two black holes are expected to be the first detected by the newly constructed gravitational wave observatories. Accurate theoretical models that describe the generation and shape of these gravitational waves need to be constructed. These theoretical waveforms will aid in the detection of astrophysical wave sources, and will allow us to test general relativity in the strong field regime. Numerical relativity is the leading candidate for constructing accurate waveforms, and in this thesis we develop methods to help advance the field. In particular we use a corotating spherical coordinate system to simulate the evolution of a compact binary system as it produces gravitational radiation. We combine this method with both the Weak Radiation Reaction and Hydro-without- Hydro approximations to produce stable dynamical evolutions. We also utilize Nordström's conformally flat theory of gravitation as a relativistic laboratory during the development process. Additionally we perform semi-analytic calculations to determine the approximate way in which binaries decay in Nordström's theory. We find an excellent agreement between our semi-analytic calculations and the orbital evolutions produced by the code, and thus conclude that these methods form a solid basis for simulating binary inspirals and the gravitational waves they produce in general relativity.

  6. Observation of D0 meson nuclear modifications in Au+Au collisions at sNN=200 GeV

    DOE PAGES

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

    2014-09-30

    We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K-+π+) in Au+Au collisions at √sNN=200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p+p to central Au+Au collisions. The D0 meson yields in central Au+Aucollisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT>3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate pT is also observed. Model calculations including strong charm-medium interactions andmore » coalescence hadronization describe our measurements.« less

  7. 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.

  8. A collision tumor of esophagus.

    PubMed

    Yao, Bin; Guan, Shanghui; Huang, Xiaochen; Su, Peng; Song, Qingxu; Cheng, Yufeng

    2015-01-01

    The collision tumor is defined by Meyer as that arisen from the accidental meeting and eventual intermingling of two independent neoplasms, which is quite rare. Most of them occur in the junction of different epithelial types of tissue such as oral cavity, esophagogastric junction, anorectaljunction and cervix, while collision tumors occurring in the liver, gallbladder, pancreatic, urinary bladder also have been reported. Here we present a case of 55-year-old Chinese man diagnosed as a collision tumor composed of leiomyosarcoma and squamous cell carcinoma (SqCC) in the lower third part of esophagus with 6 years survival after surgery and radiotherapy.

  9. Fermion tunneling beyond semiclassical approximation

    SciTech Connect

    Majhi, Bibhas Ranjan

    2009-02-15

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in R. Banerjee and B. R. Majhi, J. High Energy Phys. 06 (2008) 095 for the scalar particle, Hawking radiation as tunneling of the Dirac particle through an event horizon is analyzed. We show that, as before, all quantum corrections in the single particle action are proportional to the usual semiclassical contribution. We also compute the modifications to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. Finally, the coefficient of the logarithmic correction to entropy is shown to be related with the trace anomaly.

  10. Improved non-approximability results

    SciTech Connect

    Bellare, M.; Sudan, M.

    1994-12-31

    We indicate strong non-approximability factors for central problems: N{sup 1/4} for Max Clique; N{sup 1/10} for Chromatic Number; and 66/65 for Max 3SAT. Underlying the Max Clique result is a proof system in which the verifier examines only three {open_quotes}free bits{close_quotes} to attain an error of 1/2. Underlying the Chromatic Number result is a reduction from Max Clique which is more efficient than previous ones.

  11. Generalized Gradient Approximation Made Simple

    SciTech Connect

    Perdew, J.P.; Burke, K.; Ernzerhof, M.

    1996-10-01

    Generalized gradient approximations (GGA{close_quote}s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. {copyright} {ital 1996 The American Physical Society.}

  12. Approximate transferability in conjugated polyalkenes

    NASA Astrophysics Data System (ADS)

    Eskandari, Keiamars; Mandado, Marcos; Mosquera, Ricardo A.

    2007-03-01

    QTAIM computed atomic and bond properties, as well as delocalization indices (obtained from electron densities computed at HF, MP2 and B3LYP levels) of several linear and branched conjugated polyalkenes and O- and N-containing conjugated polyenes have been employed to assess approximate transferable CH groups. The values of these properties indicate the effects of the functional group extend to four CH groups, whereas those of the terminal carbon affect up to three carbons. Ternary carbons also modify significantly the properties of atoms in α, β and γ.

  13. Oscillator strengths and collision strengths for S v

    NASA Technical Reports Server (NTRS)

    Van Wyngaarden, W. L.; Henry, R. J. W.

    1981-01-01

    Observations of the optical extreme-ultraviolet spectrum of the Jupiter planetary system during the Voyager space mission revealed bright emission lines of some sulfur ions. The spectra of the torus at the orbit of Io are likely to contain S V lines. The described investigation provides oscillator strengths and collision strengths for the first four UV lines. The collision strengths from the ground state to four other excited states are also obtained. Use is made of a two-state calculation which is checked for convergence for some transitions by employing a three-state or a four-state approximation. Target wave functions for S V are calculated so that the oscillator strengths calculated in dipole length and dipole velocity approximations agree within 5%.

  14. Quantum mechanical calculation of the collision-induced absorption spectra of N{sub 2}–N{sub 2} with anisotropic interactions

    SciTech Connect

    Karman, Tijs; Groenenboom, Gerrit C.; Avoird, Ad van der; Miliordos, Evangelos; Hunt, Katharine L. C.

    2015-02-28

    We present quantum mechanical calculations of the collision-induced absorption spectra of nitrogen molecules, using ab initio dipole moment and potential energy surfaces. Collision-induced spectra are first calculated using the isotropic interaction approximation. Then, we improve upon these results by considering the full anisotropic interaction potential. We also develop the computationally less expensive coupled-states approximation for calculating collision-induced spectra and validate this approximation by comparing the results to numerically exact close-coupling calculations for low energies. Angular localization of the scattering wave functions due to anisotropic interactions affects the line strength at low energies by two orders of magnitude. The effect of anisotropy decreases at higher energy, which validates the isotropic interaction approximation as a high-temperature approximation for calculating collision-induced spectra. Agreement with experimental data is reasonable in the isotropic interaction approximation, and improves when the full anisotropic potential is considered. Calculated absorption coefficients are tabulated for application in atmospheric modeling.

  15. Airborne Collision Detection and Avoidance for Small UAS Sense and Avoid Systems

    NASA Astrophysics Data System (ADS)

    Sahawneh, Laith Rasmi

    The increasing demand to integrate unmanned aircraft systems (UAS) into the national airspace is motivated by the rapid growth of the UAS industry, especially small UAS weighing less than 55 pounds. Their use however has been limited by the Federal Aviation Administration regulations due to collision risk they pose, safety and regulatory concerns. Therefore, before civil aviation authorities can approve routine UAS flight operations, UAS must be equipped with sense-and-avoid technology comparable to the see-and-avoid requirements for manned aircraft. The sense-and-avoid problem includes several important aspects including regulatory and system-level requirements, design specifications and performance standards, intruder detecting and tracking, collision risk assessment, and finally path planning and collision avoidance. In this dissertation, our primary focus is on developing an collision detection, risk assessment and avoidance framework that is computationally affordable and suitable to run on-board small UAS. To begin with, we address the minimum sensing range for the sense-and-avoid (SAA) system. We present an approximate close form analytical solution to compute the minimum sensing range to safely avoid an imminent collision. The approach is then demonstrated using a radar sensor prototype that achieves the required minimum sensing range. In the area of collision risk assessment and collision prediction, we present two approaches to estimate the collision risk of an encounter scenario. The first is a deterministic approach similar to those been developed for Traffic Alert and Collision Avoidance (TCAS) in manned aviation. We extend the approach to account for uncertainties of state estimates by deriving an analytic expression to propagate the error variance using Taylor series approximation. To address unanticipated intruders maneuvers, we propose an innovative probabilistic approach to quantify likely intruder trajectories and estimate the probability of

  16. Merger of white dwarf-neutron star binaries: Prelude to hydrodynamic simulations in general relativity

    SciTech Connect

    Paschalidis, Vasileios; MacLeod, Morgan; Baumgarte, Thomas W.; Shapiro, Stuart L.

    2009-07-15

    White dwarf-neutron star binaries generate detectable gravitational radiation. We construct Newtonian equilibrium models of corotational white dwarf-neutron star (WDNS) binaries in circular orbit and find that these models terminate at the Roche limit. At this point the binary will undergo either stable mass transfer (SMT) and evolve on a secular time scale, or unstable mass transfer (UMT), which results in the tidal disruption of the WD. The path a given binary will follow depends primarily on its mass ratio. We analyze the fate of known WDNS binaries and use population synthesis results to estimate the number of LISA-resolved galactic binaries that will undergo either SMT or UMT. We model the quasistationary SMT epoch by solving a set of simple ordinary differential equations and compute the corresponding gravitational waveforms. Finally, we discuss in general terms the possible fate of binaries that undergo UMT and construct approximate Newtonian equilibrium configurations of merged WDNS remnants. We use these configurations to assess plausible outcomes of our future, fully relativistic simulations of these systems. If sufficient WD debris lands on the NS, the remnant may collapse, whereby the gravitational waves from the inspiral, merger, and collapse phases will sweep from LISA through LIGO frequency bands. If the debris forms a disk about the NS, it may fragment and form planets.

  17. Spectral formulation and WKB approximation for rare-event statistics in reaction systems.

    PubMed

    Assaf, Michael; Meerson, Baruch

    2006-10-01

    We develop a spectral formulation and a stationary WKB approximation for calculating the probabilities of rare events (large deviations from the mean) in systems of reacting particles with infinite-range interaction, describable by a master equation. We compare the stationary WKB approximation to a recent time-dependent semiclassical approximation developed, for the same class of problems, by Elgart and Kamenev [Phys. Rev. E 70, 41106 (2004)]. As a benchmark we use an exactly solvable problem of the binary annihilation reaction 2A-->0.

  18. The evolution of highly compact binary stellar systems

    NASA Technical Reports Server (NTRS)

    Rappaport, S.; Joss, P. C.; Webbink, R. F.

    1982-01-01

    A new theoretical treatment of the evolution of highly compact binary systems is presented. The evolution is calculated until almost the entire mass of the secondary has been transferred to the primary or lost from the system. It is assumed that gravitational radiation from the system is the cause of mass transfer. It is found that the structure of the mass-losing star can be approximated by an n = 3/2 polytrope, and as a result a relatively large number of different cases can be explored and some general conclusions drawn. An explanation is found for the existence of a cutoff in the orbital period distribution among the cataclysmic variables and light is shed upon the possible generic relationships among cataclysmic variables, the low-mass X-ray binaries, and the spectrally soft transient X-ray sources.

  19. Wavelet Approximation in Data Assimilation

    NASA Technical Reports Server (NTRS)

    Tangborn, Andrew; Atlas, Robert (Technical Monitor)

    2002-01-01

    Estimation of the state of the atmosphere with the Kalman filter remains a distant goal because of high computational cost of evolving the error covariance for both linear and nonlinear systems. Wavelet approximation is presented here as a possible solution that efficiently compresses both global and local covariance information. We demonstrate the compression characteristics on the the error correlation field from a global two-dimensional chemical constituent assimilation, and implement an adaptive wavelet approximation scheme on the assimilation of the one-dimensional Burger's equation. In the former problem, we show that 99%, of the error correlation can be represented by just 3% of the wavelet coefficients, with good representation of localized features. In the Burger's equation assimilation, the discrete linearized equations (tangent linear model) and analysis covariance are projected onto a wavelet basis and truncated to just 6%, of the coefficients. A nearly optimal forecast is achieved and we show that errors due to truncation of the dynamics are no greater than the errors due to covariance truncation.

  20. Laguerre approximation of random foams

    NASA Astrophysics Data System (ADS)

    Liebscher, André

    2015-09-01

    Stochastic models for the microstructure of foams are valuable tools to study the relations between microstructure characteristics and macroscopic properties. Owing to the physical laws behind the formation of foams, Laguerre tessellations have turned out to be suitable models for foams. Laguerre tessellations are weighted generalizations of Voronoi tessellations, where polyhedral cells are formed through the interaction of weighted generator points. While both share the same topology, the cell curvature of foams allows only an approximation by Laguerre tessellations. This makes the model fitting a challenging task, especially when the preservation of the local topology is required. In this work, we propose an inversion-based approach to fit a Laguerre tessellation model to a foam. The idea is to find a set of generator points whose tessellation best fits the foam's cell system. For this purpose, we transform the model fitting into a minimization problem that can be solved by gradient descent-based optimization. The proposed algorithm restores the generators of a tessellation if it is known to be Laguerre. If, as in the case of foams, no exact solution is possible, an approximative solution is obtained that maintains the local topology.

  1. Main Sequence Binary Fraction in Globular Cluster NGC 6397

    NASA Astrophysics Data System (ADS)

    Srinath, Srikar; Cool, A. M.; Anderson, J.

    2011-01-01

    We report preliminary results from a study of main-sequence binaries (MSBs) in the core-collapsed globular cluster NGC 6397 using the Hubble Space Telescope (HST) Advanced Camera for Surveys. We analyze images of the central regions of the cluster extending out to approximately one half-mass radius (rhm = 2.33') taken with the Wide Field Channel in the F435W and F625W filters. After removing non-members using proper motions, we construct a color-magnitude diagram (CMD) containing 15578 cluster stars. Model cluster CMDs indicate that in the range 16 < R < 22, MSBs with mass ratio (q=M2/M1) > 0.6 appear sufficiently far above and redward of the main sequence ridge line to be distinguishable from the single-star sequence. Out of 10835 stars in this magnitude range, we identify an initial set of 137 stars (with primary masses in the range 0.4-0.7 Msun) whose offset from the single-star sequence is statistically significant. A check of quality of fit to the PSF combined with close visual inspection of the images shows that 85 of these stars are well measured and unresolved and are thus good MSB candidates. The resulting upper limit on the fraction of MSBs with q > 0.6 and primaries in the range 0.4-0.7 Msun is 0.8%. We compare our measured fraction and the radial distribution of the MSB candidates to earlier findings based on HST/WFPC2 imaging and explore the significance of the results for the total binary population in NGC 6397. Keywords: binaries: general - globular clusters: individual(NGC 6397) - binary fraction - stars: main sequence binary

  2. Forecast Modelling via Variations in Binary Image-Encoded Information Exploited by Deep Learning Neural Networks

    PubMed Central

    Xu, Ming; Niu, Dongxiao; Wang, Shoukai; Liang, Sai

    2016-01-01

    Traditional forecasting models fit a function approximation from dependent invariables to independent variables. However, they usually get into trouble when date are presented in various formats, such as text, voice and image. This study proposes a novel image-encoded forecasting method that input and output binary digital two-dimensional (2D) images are transformed from decimal data. Omitting any data analysis or cleansing steps for simplicity, all raw variables were selected and converted to binary digital images as the input of a deep learning model, convolutional neural network (CNN). Using shared weights, pooling and multiple-layer back-propagation techniques, the CNN was adopted to locate the nexus among variations in local binary digital images. Due to the computing capability that was originally developed for binary digital bitmap manipulation, this model has significant potential for forecasting with vast volume of data. The model was validated by a power loads predicting dataset from the Global Energy Forecasting Competition 2012. PMID:27281032

  3. Search for gravitational waves from binary black hole inspiral, merger, and ringdown

    NASA Astrophysics Data System (ADS)

    Abadie, J.; Abbott, B. P.; Abbott, R.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Ajith, P.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Antonucci, F.; Arain, M. A.; Araya, M. C.; Aronsson, M.; Aso, Y.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Babak, S.; Baker, P.; Ballardin, G.; Ballinger, T.; Ballmer, S.; Barker, D.; Barnum, S.; Barone, F.; Barr, B.; Barriga, P.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Bauchrowitz, J.; Bauer, Th. S.; Behnke, B.; Beker, M. G.; Belletoile, A.; Benacquista, M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birindelli, S.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Boccara, C.; Bock, O.; Bodiya, T. P.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Boyle, M.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Budzyński, R.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Burmeister, O.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cain, J.; Calloni, E.; Camp, J. B.; Campagna, E.; Campsie, P.; Cannizzo, J.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chaibi, O.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chassande-Mottin, E.; Chelkowski, S.; Chen, Y.; Chincarini, A.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Clark, D.; Clark, J.; Clayton, J. H.; Cleva, F.; Coccia, E.; Colacino, C. N.; Colas, J.; Colla, A.; Colombini, M.; Conte, R.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coulon, J.-P.; Coward, D. M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Culter, R. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Danilishin, S. L.; Dannenberg, R.; D'Antonio, S.; Danzmann, K.; Das, K.; Dattilo, V.; Daudert, B.; Davier, M.; Davies, G.; Davis, A.; Daw, E. J.; Day, R.; Dayanga, T.; Derosa, R.; Debra, D.; Debreczeni, G.; Degallaix, J.; Del Prete, M.; Dergachev, V.; de Rosa, R.; Desalvo, R.; Devanka, P.; Dhurandhar, S.; di Fiore, L.; di Lieto, A.; di Palma, I.; di Paolo Emilio, M.; di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doomes, E. E.; Dorsher, S.; Douglas, E. S. D.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Dueck, J.; Dumas, J.-C.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Ely, G.; Engel, R.; Etzel, T.; Evans, M.; Evans, T.; Fafone, V.; Fairhurst, S.; Fan, Y.; Farr, B. F.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Flaminio, R.; Flanigan, M.; Flasch, K.; Foley, S.; Forrest, C.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Galimberti, M.; Gammaitoni, L.; Garofoli, J. A.; Garufi, F.; Gáspár, M. E.; Gemme, G.; Genin, E.; Gennai, A.; Gholami, I.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gill, C.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Greverie, C.; Grosso, R.; Grote, H.; Grunewald, S.; Guidi, G. M.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hall, P.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Hayler, T.; Heefner, J.; Heitmann, H.; Hello, P.; Heng, I. S.; Heptonstall, A. W.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hodge, K. A.; Holt, K.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hoyland, D.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Jaranowski, P.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kanner, J. B.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, H.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Kowalska, I.; Kozak, D.; Krause, T.; Kringel, V.; Krishnamurthy, S.; Krishnan, B.; Królak, A.; Kuehn, G.; Kullman, J.; Kumar, R.; Kwee, P.; Landry, M.; Lang, M.; Lantz, B.; Lastzka, N.; Lazzarini, A.; Leaci, P.; Leong, J.; Leonor, I.; Leroy, N.; Letendre, N.; Li, J.; Li, T. G. F.; Liguori, N.; Lin, H.; Lindquist, P. E.; Lockerbie, N. A.; Lodhia, D.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lu, P.; Luan, J.; Lubiński, M.; Lucianetti, A.; Lück, H.; Lundgren, A. D.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Mak, C.; Maksimovic, I.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIvor, G.; McKechan, D. J. A.; Meadors, G.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menéndez, D. F.; Mercer, R. A.; Merill, L.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mino, Y.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohanty, S. D.; Mohapatra, S. R. P.; Moraru, D.; Moreau, J.; Moreno, G.; Morgado, N.; Morgia, A.; Morioka, T.; Mors, K.; Mosca, S.; Moscatelli, V.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murray, P. G.; Nash, T.; Nawrodt, R.; Nelson, J.; Neri, I.; Newton, G.; Nishizawa, A.; Nocera, F.; Nolting, D.; Ochsner, E.; O'Dell, J.; Ogin, G. H.; Oldenburg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Pagliaroli, G.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Papa, M. A.; Pardi, S.; Pareja, M.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patel, P.; Pathak, D.; Pedraza, M.; Pekowsky, L.; Penn, S.; Peralta, C.; Perreca, A.; Persichetti, G.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pietka, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Poggiani, R.; Postiglione, F.; Prato, M.; Predoi, V.; Price, L. R.; Prijatelj, M.; Principe, M.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radke, T.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, P.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rolland, L.; Rollins, J.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sakata, S.; Sakosky, M.; Salemi, F.; Sammut, L.; Sancho de La Jordana, L.; Sandberg, V.; Sannibale, V.; Santamaría, L.; Santostasi, G.; Saraf, S.; Sassolas, B.; Sathyaprakash, B. S.; Sato, S.; Satterthwaite, M.; Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Searle, A. C.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Singer, A.; Sintes, A. M.; Skelton, G.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, N. D.; Somiya, K.; Sorazu, B.; Speirits, F. C.; Sperandio, L.; Stein, A. J.; Stein, L. C.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szokoly, G. P.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, J. R.; Taylor, R.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Trias, M.; Tseng, K.; Turner, L.; Ugolini, D.; Urbanek, K.; Vahlbruch, H.; Vaishnav, B.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; van den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Veltkamp, C.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vocca, H.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Wanner, A.; Ward, R. L.; Was, M.; Wei, P.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wen, S.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, L.; Willke, B.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Woan, G.; Wooley, R.; Worden, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yeaton-Massey, D.; Yoshida, S.; Yu, P.; Yvert, M.; Zanolin, M.; Zhang, L.; Zhang, Z.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration

    2011-06-01

    We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99M⊙ and total masses of 25-100M⊙. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19M⊙≤m1, m2≤28M⊙ binary black-hole systems with negligible spin to be no more than 2.0Mpc-3Myr-1 at 90% confidence.

  4. Remnant massive neutron stars of binary neutron star mergers: Evolution process and gravitational waveform

    NASA Astrophysics Data System (ADS)

    Hotokezaka, Kenta; Kiuchi, Kenta; Kyutoku, Koutarou; Muranushi, Takayuki; Sekiguchi, Yu-ichiro; Shibata, Masaru; Taniguchi, Keisuke

    2013-08-01

    Massive (hypermassive and supramassive) neutron stars are likely to be often formed after the merger of binary neutron stars. We explore the evolution process of the remnant massive neutron stars and gravitational waves emitted by them, based on numerical-relativity simulations for binary neutron star mergers employing a variety of equations of state and choosing a plausible range of the neutron star mass of binaries. We show that the lifetime of remnant hypermassive neutron stars depends strongly on the total binary mass and also on the equations of state. Gravitational waves emitted by the remnant massive neutron stars universally have a quasiperiodic nature of an approximately constant frequency although the frequency varies with time. We also show that the frequency and time-variation feature of gravitational waves depend strongly on the equations of state. We derive a fitting formula for the quasiperiodic gravitational waveforms, which may be used for the data analysis of a gravitational-wave signal.

  5. Monte Carlo next-event estimates from thermal collisions

    SciTech Connect

    Hendricks, J.S.; Prael, R.E.

    1990-01-01

    A new approximate method has been developed by Richard E. Prael to allow S({alpha},{beta}) thermal collision contributions to next-event estimators in Monte Carlo calculations. The new technique is generally applicable to next-event estimator contributions from any discrete probability distribution. The method has been incorporated into Version 4 of the production Monte Carlo neutron and photon radiation transport code MCNP. 9 refs.

  6. Inelastic collisions of positrons with one-valence-electron targets

    NASA Technical Reports Server (NTRS)

    Abdel-Raouf, Mohamed Assad

    1990-01-01

    The total elastic and positronium formation cross sections of the inelastic collisions between positrons and various one-valence-electron atoms, (namely hydrogen, lithium, sodium, potassium and rubidium), and one-valence-electron ions, (namely hydrogen-like, lithium-like and alkaline-earth positive ions) are determined using an elaborate modified coupled-static approximation. Special attention is devoted to the behavior of the Ps cross sections at the energy regions lying above the Ps formation thresholds.

  7. Bremsstrahlung background in inelastic electron–nucleus collisions

    NASA Astrophysics Data System (ADS)

    Jakubassa-Amundsen, D. H.; Krugmann, A.

    2017-04-01

    Bremsstrahlung emission by relativistic electrons in collisions with medium heavy spin-zero nuclei is calculated within the plane-wave Born approximation. Coulomb distortion is estimated by a comparison with the Dirac partial-wave theory at energies up to 20 MeV. When integrated over the photon emission angle, the bremsstrahlung spectra help to explain the background of the nuclear excitation spectra in 150Nd (e,e\\prime ) reactions which were recently measured on an absolute scale.

  8. 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.

  9. 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.

  10. 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.

  11. Milky Way's Head On Collision

    NASA Video Gallery

    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...

  12. On the unreasonable effectiveness of the post-Newtonian approximation in gravitational physics

    PubMed Central

    Will, Clifford M.

    2011-01-01

    The post-Newtonian approximation is a method for solving Einstein’s field equations for physical systems in which motions are slow compared to the speed of light and where gravitational fields are weak. Yet it has proven to be remarkably effective in describing certain strong-field, fast-motion systems, including binary pulsars containing dense neutron stars and binary black hole systems inspiraling toward a final merger. The reasons for this effectiveness are largely unknown. When carried to high orders in the post-Newtonian sequence, predictions for the gravitational-wave signal from inspiraling compact binaries will play a key role in gravitational-wave detection by laser-interferometric observatories. PMID:21447714

  13. Observation of D0 meson nuclear modifications in Au+Au collisions at sqrt[s(NN)] = 200 GeV.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-10-03

    We report the first measurement of charmed-hadron (D(0)) production via the hadronic decay channel (D(0) → K(-) + π(+)) in Au+Au collisions at sqrt[s(NN)] = 200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, N(bin), from p+p to central Au+Au collisions. The D(0) meson yields in central Au + Au collisions are strongly suppressed compared to those in p+p scaled by N(bin), for transverse momenta p(T) > 3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate p(T) is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.

  14. Airborne Collision Avoidance System X

    DTIC Science & Technology

    2015-06-01

    avoidance system on behalf of the Federal Aviation Adminis- tration (FAA). The current Traffic Alert and Collision Avoidance System II (TCAS II...which are used on board an aircraft. The tables provide a cost for each action—no alert , a traffic advisory alerting pilots about nearby aircraft, or a...suitabil- ity than does TCAS II; studies show that ACAS X reduces mid-air collision risk by 59% and unnecessary disruptive alerts by 25% when

  15. 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.

  16. Injuries from motor-vehicle collisions with moose--Maine, 2000-2004.

    PubMed

    2006-12-01

    Moose are among the largest mammals in North America. Standing up to 7.5 feet at the shoulder and weighing up to 1,600 lbs, they are the largest members of the deer family. Maine's moose population (approximately 29,000) is the biggest in the United States outside of Alaska. During a collision with a motor vehicle, a moose usually is struck in the legs, causing its body to roll onto the hood of the vehicle, often collapsing the windshield and roof. As a result, motor-vehicle collisions involving moose are capable of causing substantial injury to vehicle occupants. To assess motor-vehicle collisions with moose in Maine and evaluate risk factors for injuries from these types of collisions, the Maine Department of Health and Human Services studied collision reports from 2000--2004. The results of that study indicated that collision rates varied by county but had clear patterns by season and time of day. Variables associated with risk for injury were posted speed limit, type of vehicle, and sex and age of the driver. Measures to reduce collisions with moose should focus on improving driver education programs and developing better engineering controls (e.g., removing roadside vegetation to improve visibility for drivers). In addition, herd management (i.e., decreasing moose population size through hunting) is currently being used in areas of Maine with high numbers of collisions, although studies are needed to assess its effectiveness.

  17. General theory of electron detachment in negative ion collisions

    SciTech Connect

    Wang, T.S.

    1983-01-01

    In this thesis a general theory of electron detachment in slow collisions of negative ions with atoms is presented. The theory is based upon a semiclassical close-coupling framework, following the work of Taylor and Delos. The Schrodinger equation is reduced, under certain assumptions, to a non-denumerably infinite set of coupled equations. A new method for solving these equations is developed that is more general than the methods used by Taylor and Delos. A zero-order approximation of the solution is applied to the case of H-(D-) on Ne collisions, the results are compared with the experimental data, and good agreement between theory and experiment, particularly with regard to the isotope effect, is found. A first-order approximation of the solution is proved to be very close to the exact solution, and it is applied to the case of H-(D-) on He collisions. Quadratic and quartic approximations are used for the energy gap ..delta..(t) to calculate, among other things, the survival probability and electron energy spectrum. There are some interesting results of the electron energy spectrum which have not yet been observed in experiments.

  18. Analytical approximations for spiral waves

    SciTech Connect

    Löber, Jakob Engel, Harald

    2013-12-15

    We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency Ω and core radius R{sub 0}. For free, rigidly rotating spiral waves our analytical prediction is in good agreement with numerical solutions of the linear eikonal equation not only for very large but also for intermediate and small values of the core radius. An equivalent Ω(R{sub +}) dependence improves the result by Keener and Tyson for spiral waves pinned to a circular defect of radius R{sub +} with Neumann boundaries at the periphery. Simultaneously, analytical approximations for the shape of free and pinned spirals are given. We discuss the reasons why the ansatz fails to correctly describe the dependence of the rotation frequency on the excitability of the medium.

  19. Approximating metal-insulator transitions

    NASA Astrophysics Data System (ADS)

    Danieli, Carlo; Rayanov, Kristian; Pavlov, Boris; Martin, Gaven; Flach, Sergej

    2015-12-01

    We consider quantum wave propagation in one-dimensional quasiperiodic lattices. We propose an iterative construction of quasiperiodic potentials from sequences of potentials with increasing spatial period. At each finite iteration step, the eigenstates reflect the properties of the limiting quasiperiodic potential properties up to a controlled maximum system size. We then observe approximate Metal-Insulator Transitions (MIT) at the finite iteration steps. We also report evidence on mobility edges, which are at variance to the celebrated Aubry-André model. The dynamics near the MIT shows a critical slowing down of the ballistic group velocity in the metallic phase, similar to the divergence of the localization length in the insulating phase.

  20. Analytical approximations for spiral waves.

    PubMed

    Löber, Jakob; Engel, Harald

    2013-12-01

    We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency Ω and core radius R(0). For free, rigidly rotating spiral waves our analytical prediction is in good agreement with numerical solutions of the linear eikonal equation not only for very large but also for intermediate and small values of the core radius. An equivalent Ω(R(+)) dependence improves the result by Keener and Tyson for spiral waves pinned to a circular defect of radius R(+) with Neumann boundaries at the periphery. Simultaneously, analytical approximations for the shape of free and pinned spirals are given. We discuss the reasons why the ansatz fails to correctly describe the dependence of the rotation frequency on the excitability of the medium.

  1. Indexing the approximate number system.

    PubMed

    Inglis, Matthew; Gilmore, Camilla

    2014-01-01

    Much recent research attention has focused on understanding individual differences in the approximate number system, a cognitive system believed to underlie human mathematical competence. To date researchers have used four main indices of ANS acuity, and have typically assumed that they measure similar properties. Here we report a study which questions this assumption. We demonstrate that the numerical ratio effect has poor test-retest reliability and that it does not relate to either Weber fractions or accuracy on nonsymbolic comparison tasks. Furthermore, we show that Weber fractions follow a strongly skewed distribution and that they have lower test-retest reliability than a simple accuracy measure. We conclude by arguing that in the future researchers interested in indexing individual differences in ANS acuity should use accuracy figures, not Weber fractions or numerical ratio effects.

  2. Binary nucleation at low temperatures

    NASA Technical Reports Server (NTRS)

    Zahoransky, R. A.; Peters, F.

    1985-01-01

    The onset of homogeneous condensation of binary vapors in the supersaturated state is studied in ethanol/n-propanol and water/ethanol via their unsteady expansion in a shock tube at temperatures below 273 K. Ethanol/n-propanol forms a nearly ideal solution, whereas water/ethanol is an example of a strongly nonideal mixture. Vapor mixtures of various compositions are diluted in dry air at small mole fractions and expanded in the driver section from room temperature. The onset of homogeneous condensation is detected optically and the corresponding thermodynamic state is evaluated. The experimental results are compared with the binary nucleation theory, and the particular problems of theoretical evaluation at low temperatures are discussed.

  3. Binary Stars in SBS Survey

    NASA Astrophysics Data System (ADS)

    Erastova, L. K.

    2016-06-01

    Thirty spectroscopic binary stars were found in the Second Byurakan Survey (SBS). They show composite spectra - WD(DA)+dM or dC (for example Liebert et al. 1994). They may have red color, if the radiation of the red star dominates, and blue one, if the blue star is brighter and have peculiar spectrum in our survey plate. We obtained slit spectra for most of such objects. But we often see the spectrum of one component, because our slit spectra did not cover all optical range. We examine by eye the slit spectra of all SBS stellar objects (˜700) in SDSS DR7, DR8 or DR9 independent on our observations. We confirmed or discovered the duplicity of 30 stars. Usually they are spectroscopic binaries, where one component is WD (DA) and the second one is a red star with or without emission. There also are other components combinations. Sometimes there are emission lines, probably, indicating variable ones.

  4. Mass transfer between binary stars

    NASA Technical Reports Server (NTRS)

    Modisette, J. L.; Kondo, Y.

    1980-01-01

    The transfer of mass from one component of a binary system to another by mass ejection is analyzed through a stellar wind mechanism, using a model which integrates the equations of motion, including the energy equation, with an initial static atmosphere and various temperature fluctuations imposed at the base of the star's corona. The model is applied to several situations and the energy flow is calculated along the line of centers between the two binary components, in the rotating frame of the system, thereby incorporating the centrifugal force. It is shown that relatively small disturbances in the lower chromosphere or photosphere can produce mass loss through a stellar wind mechanism, due to the amplification of the disturbance propagating into the thinner atmosphere. Since there are many possible sources of the disturbance, the model can be used to explain many mass ejection phenomena.

  5. Close supermassive binary black holes.

    PubMed

    Gaskell, C Martin

    2010-01-07

    It has been proposed that when the peaks of the broad emission lines in active galactic nuclei (AGNs) are significantly blueshifted or redshifted from the systemic velocity of the host galaxy, this could be a consequence of orbital motion of a supermassive black-hole binary (SMBB). The AGN J1536+0441 ( = SDSS J153636.22+044127.0) has recently been proposed as an example of this phenomenon. It is proposed here instead that J1536+0441 is an example of line emission from a disk. If this is correct, the lack of clear optical spectral evidence for close SMBBs is significant, and argues either that the merging of close SMBBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted.

  6. Approximate analytic solutions to the NPDD: Short exposure approximations

    NASA Astrophysics Data System (ADS)

    Close, Ciara E.; Sheridan, John T.

    2014-04-01

    There have been many attempts to accurately describe the photochemical processes that take places in photopolymer materials. As the models have become more accurate, solving them has become more numerically intensive and more 'opaque'. Recent models incorporate the major photochemical reactions taking place as well as the diffusion effects resulting from the photo-polymerisation process, and have accurately described these processes in a number of different materials. It is our aim to develop accessible mathematical expressions which provide physical insights and simple quantitative predictions of practical value to material designers and users. In this paper, starting with the Non-Local Photo-Polymerisation Driven Diffusion (NPDD) model coupled integro-differential equations, we first simplify these equations and validate the accuracy of the resulting approximate model. This new set of governing equations are then used to produce accurate analytic solutions (polynomials) describing the evolution of the monomer and polymer concentrations, and the grating refractive index modulation, in the case of short low intensity sinusoidal exposures. The physical significance of the results and their consequences for holographic data storage (HDS) are then discussed.

  7. EQUILIBRIUM CONFIGURATIONS OF SYNCHRONOUS BINARIES: NUMERICAL SOLUTIONS AND APPLICATION TO KUIPER BELT BINARY 2001 QG{sub 298}

    SciTech Connect

    Gnat, Orly; Sari, Re'em

    2010-08-20

    We present numerical computations of the equilibrium configurations of tidally locked homogeneous binaries rotating in circular orbits. Unlike the classical Roche approximations, we self-consistently account for the tidal and rotational deformations of both components, and relax the assumptions of ellipsoidal configurations and Keplerian rotation. We find numerical solutions for mass ratios q between 10{sup -3} and 1, starting at a small angular velocity for which tidal and rotational deformations are small, and following a sequence of increasing angular velocities. Each series terminates at an appropriate 'Roche limit', above which no equilibrium solution can be found. Even though the Roche limit is crossed before the 'Roche lobe' is filled, any further increase in the angular velocity will result in mass-loss. For close, comparable-mass binaries, we find that local deviations from ellipsoidal forms may be as large as 10%-20%, and departures from Keplerian rotation are significant. We compute the light curves that arise from our equilibrium configurations, assuming their distance is >>1 AU (e.g., in the Kuiper Belt). We consider both backscatter (proportional to the projected area) and diffuse (Lambert) reflections. Backscatter reflection always yields two minima of equal depths. Diffuse reflection, which is sensitive to the surface curvature, generally gives rise to unequal minima. We find detectable intensity differences of up to 10% between our light curves and those arising from the Roche approximations. Finally, we apply our models to Kuiper Belt binary 2001 QG{sub 298}, and find a nearly edge-on binary with a mass ratio q = 0.93{sup +0.07}{sub -0.03}, angular velocity {omega}{sup 2}/G{rho} = 0.333 {+-} 0.001 (statistical errors only), and pure diffuse reflection. For the observed period of 2001 QG{sub 298}, these parameters imply a bulk density {rho} = 0.72 {+-} 0.04 g cm{sup -3}.

  8. Collision-induced gas phase dissociation rates

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1990-01-01

    The Landau-Zener theory of reactive cross sections was applied to diatomic molecules dissociating from a ladder of vibrational states. The result predicts a dissociation rate that is quite well duplicated by an Arrhenius function having a preexponential temperature dependence of about T(sub -1/2), at least for inert collision partners. This relation fits experimental data reasonably well. The theory is then used to calculate the effect of vibrational nonequilibrium on dissociation rate. For Morse oscillators, the results are about the same as given by Hammerling, Kivel, and Teare in their analytic approximation for harmonic oscillators, though at very high temperature a correction for the partition function limit is included. The empirical correction for vibration nonequilibrium proposed by Park, which is a convenient algorithm for CFD calculations, is modified to prevent a drastic underestimation of dissociation rates that occurs with this method when vibrational temperature is much smaller than the kinetic temperature of the gas.

  9. Saturation Effect of Projectile Excitation in Ion-Atom Collisions

    NASA Astrophysics Data System (ADS)

    Mukoyama, Takeshi; Lin, Chii-Dong

    Calculations of projectile K-shell electron excitation cross sections for He-like ions during ion-atom collisions have been performed in the distortion approximation by the use of Herman-Skillman wave functions. The calculated results are compared with the experimental data for several targets. The excitation cross sections deviate from the first-Born approximation and show the saturation effect as a function of target atomic number. This effect can be explained as the distortion of the projectile electronic states by the target nucleus.

  10. Semiclassical theory of inelastic collisions. II - Momentum-space formulation.

    NASA Technical Reports Server (NTRS)

    Delos, J. B.; Thorson, W. R.

    1972-01-01

    The time-dependent equations of the classical picture of inelastic collisions (classical-trajectory equations) are derived using the momentum-space semiclassical approximation. Thereby it is shown that the classical-trajectory equations remain valid in the vicinity of classical turning points provided that (a) the momentum-space semiclassical approximation is valid, (b) the trajectories for elastic scattering in the various internal states differ only slightly, and (c) the slopes of the elastic scattering potentials have the same sign. A brief review of the existing derivations of the classical-trajectory equations is given, and the general conditions for their validity are discussed.

  11. Υ production in U + U collisions at sNN=193 GeV measured with the STAR experiment

    DOE PAGES

    Adamczyk, L.

    2016-12-15

    We present a measurement of the inclusive production of ¡ mesons in U+U collisions at √sNN = 193 GeV at mid-rapidity (|y| < 1). Previous studies in central Au+Au collisions at √sNN = 200 GeV show a suppression of ¡(1S+2S+3S) production relative to expectations from the ¡ yield in p+p collisions scaled by the number of binary nucleon-nucleon collisions (Ncoll), with an indication that the ¡(1S) state is also suppressed. The present measurement extends the number of participant nucleons in the collision (Npart) by 20% compared to Au+Au collisions, and allows us to study a system with higher energy density.more » We observe a suppression in both the ¡(1S+2S+3S) and ¡(1S) yields in central U+U data, which consolidates and extends the previously observed suppression trend in Au+Au collisions.« less

  12. Modeling and Simulation of an UAS Collision Avoidance Systems

    NASA Technical Reports Server (NTRS)

    Oliveros, Edgardo V.; Murray, A. Jennifer

    2010-01-01

    This paper describes a Modeling and Simulation of an Unmanned Aircraft Systems (UAS) Collision Avoidance System, capable of representing different types of scenarios for UAS collision avoidance. Commercial and military piloted aircraft currently utilize various systems for collision avoidance such as Traffic Alert and Collision A voidance System (TCAS), Automatic Dependent Surveillance-Broadcast (ADS-B), Radar and ElectroOptical and Infrared Sensors (EO-IR). The integration of information from these systems is done by the pilot in the aircraft to determine the best course of action. In order to operate optimally in the National Airspace System (NAS) UAS have to work in a similar or equivalent manner to a piloted aircraft by applying the principle of "detect-see and avoid" (DSA) to other air traffic. Hence, we have taken these existing sensor technologies into consideration in order to meet the challenge of researching the modeling and simulation of an approximated DSA system. A Schematic Model for a UAS Collision Avoidance System (CAS) has been developed ina closed loop block diagram for that purpose. We have found that the most suitable software to carry out this task is the Satellite Tool Kit (STK) from Analytical Graphics Inc. (AGI). We have used the Aircraft Mission Modeler (AMM) for modeling and simulation of a scenario where a UAS is placed on a possible collision path with an initial intruder and then with a second intruder, but is able to avoid them by executing a right tum maneuver and then climbing. Radars have also been modeled with specific characteristics for the UAS and both intruders. The software provides analytical, graphical user interfaces and data controlling tools which allow the operator to simulate different conditions. Extensive simulations have been carried out which returned excellent results.

  13. Hints for Hidden Planetary Companions to Hot Jupiters in Stellar Binaries

    NASA Astrophysics Data System (ADS)

    Hamers, Adrian S.

    2017-02-01

    Searches for stellar companions to hot Jupiters (HJs) have revealed that planetary systems hosting an HJ are approximately three times more likely to have a stellar companion with a semimajor axis between 50 and 2000 au, compared to field stars. This correlation suggests that HJ formation is affected by the stellar binary companion. A potential model is high-eccentricity migration, in which the binary companion induces high-eccentricity Lidov–Kozai (LK) oscillations in the proto-HJ orbit, triggering orbital migration driven by tides. A pitfall of this “binary-LK” model is that the observed stellar binaries hosting HJs are typically too wide to produce HJs in sufficient numbers because of suppression by short-range forces. We propose a modification to the binary-LK model in which there is a second giant planet orbiting the proto-HJ at a semimajor axis of several tens of au. Such companions are currently hidden to observations, but their presence could be manifested by a propagation of the perturbation of the stellar binary companion inward to the proto-HJ, thereby overcoming the barrier imposed by short-range forces. Our model does not require the planetary companion orbit to be eccentric and/or inclined with respect to the proto-HJ, but its semimajor axis should lie in a specific range given the planetary mass and binary semimajor axis, and the inclination with respect to the binary should be near 40° or 140°. Our prediction for planetary companions to HJs in stellar binaries should be testable by future observations.

  14. Forward J/ψ production in U + U collisions at sNN=193 GeV

    DOE PAGES

    Adare, A.; Aidala, C.; Ajitanand, N. N.; ...

    2016-03-03

    We measured the invariant yields, dN/dy, for J/psi production at forward rapidity (1.2 < |y| < 2.2) in U + U collisions at √SNN = 193 GeV as a function of collision centrality. The invariant yields and nuclear-modification factor R-AA are presented and compared with those from Au + Au collisions in the same rapidity range. In addition, the direct ratio of the invariant yields from U + U and Au + Au collisions within the same centrality class is presented, and used to investigate the role of cmore » $$\\bar{c}$$ over bar coalescence. Two different parametrizations of the deformed Woods-Saxon distribution were used in Glauber calculations to determine the values of the number of nucleon-nucleon collisions in each centrality class, N-coll, and these were found to give significantly different Ncoll values. Our results, using Ncoll values from both deformed Woods-Saxon distributions are presented. The measured ratios show that the J/psi suppression, relative to binary collision scaling, is similar in U + U and Au + Au for peripheral and midcentral collisions, but that J/psi show less suppression for the most central U + U collisions. The results are consistent with a picture in which, for central collisions, increase in the J/psi yield due to c $$\\bar{c}$$) over bar coalescence becomes more important than the decrease in yield due to increased energy density. Finally, for midcentral collisions, the conclusions about the balance between c $$\\bar{c}$$ over bar coalescence and suppression depend on which deformed Woods-Saxon distribution is used to determine Ncoll.« less

  15. Forward J /ψ production in U + U collisions at √{sN N}=193 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Asano, H.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bai, X.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bathe, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Christiansen, P.; Chujo, T.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Cronin, N.; Crossette, N.; Csanád, M.; Csörgő, T.; Danley, T. W.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Diss, P. B.; Do, J. H.; D'Orazio, L.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Engelmore, T.; Enokizono, A.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; Hashimoto, K.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Ichihara, T.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Isinhue, A.; Ivanishchev, D.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Kawall, D.; Kazantsev, A. V.; Key, J. A.; Khachatryan, V.; Khandai, P. K.; Khanzadeev, A.; Kijima, K. M.; Kim, C.; Kim, D. J.; Kim, E.-J.; Kim, G. W.; Kim, M.; Kim, Y.-J.; Kim, Y. K.; Kimelman, B.; Kistenev, E.; Kitamura, R.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Krizek, F.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, G. H.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S.; Lee, S. H.; Leitch, M. J.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Liu, M. X.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Maruyama, T.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Mohapatra, S.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagashima, K.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nishimura, S.; Nouicer, R.; Novák, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Oide, H.; Okada, K.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J. S.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Peng, J.-C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Qu, H.; Rak, J.; Ramson, B. J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Rinn, T.; Riveli, N.; Roach, D.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Ryu, M. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sekiguchi, Y.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shaver, A.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Skolnik, M.; Slunečka, M.; Snowball, M.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Steinberg, P.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Stone, M. R.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takahara, A.; Taketani, A.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, C. L.

    2016-03-01

    The invariant yields, d N /d y , for J /ψ production at forward rapidity (1.2 <|y |<2.2 ) in U +U collisions at √{sNN}=193 GeV have been measured as a function of collision centrality. The invariant yields and nuclear-modification factor RA A are presented and compared with those from Au +Au collisions in the same rapidity range. Additionally, the direct ratio of the invariant yields from U +U and Au +Au collisions within the same centrality class is presented, and used to investigate the role of c c ¯ coalescence. Two different parametrizations of the deformed Woods-Saxon distribution were used in Glauber calculations to determine the values of the number of nucleon-nucleon collisions in each centrality class, Ncoll, and these were found to give significantly different Ncoll values. Results using Ncoll values from both deformed Woods-Saxon distributions are presented. The measured ratios show that the J /ψ suppression, relative to binary collision scaling, is similar in U +U and Au +Au for peripheral and midcentral collisions, but that J /ψ show less suppression for the most central U +U collisions. The results are consistent with a picture in which, for central collisions, increase in the J /ψ yield due to c c ¯ coalescence becomes more important than the decrease in yield due to increased energy density. For midcentral collisions, the conclusions about the balance between c c ¯ coalescence and suppression depend on which deformed Woods-Saxon distribution is used to determine Ncoll.

  16. Compact Objects In Binary Systems: Formation and Evolution of X-ray Binaries and Tides in Double White Dwarfs

    NASA Astrophysics Data System (ADS)

    Valsecchi, Francesca

    Binary star systems hosting black holes, neutron stars, and white dwarfs are unique laboratories for investigating both extreme physical conditions, and stellar and binary evolution. Black holes and neutron stars are observed in X-ray binaries, where mass accretion from a stellar companion renders them X-ray bright. Although instruments like Chandra have revolutionized the field of X-ray binaries, our theoretical understanding of their origin and formation lags behind. Progress can be made by unravelling the evolutionary history of observed systems. As part of my thesis work, I have developed an analysis method that uses detailed stellar models and all the observational constraints of a system to reconstruct its evolutionary path. This analysis models the orbital evolution from compact-object formation to the present time, the binary orbital dynamics due to explosive mass loss and a possible kick at core collapse, and the evolution from the progenitor's Zero Age Main Sequence to compact-object formation. This method led to a theoretical model for M33 X-7, one of the most massive X-ray binaries known and originally marked as an evolutionary challenge. Compact objects are also expected gravitational wave (GW) sources. In particular, double white dwarfs are both guaranteed GW sources and observed electromagnetically. Although known systems show evidence of tidal deformation and a successful GW astronomy requires realistic models of the sources, detached double white dwarfs are generally approximated to point masses. For the first time, I used realistic models to study tidally-driven periastron precession in eccentric binaries. I demonstrated that its imprint on the GW signal yields constrains on the components' masses and that the source would be misclassified if tides are neglected. Beyond this adiabatic precession, tidal dissipation creates a sink of orbital angular momentum. Its efficiency is strongest when tides are dynamic and excite the components' free

  17. Post-common envelope binaries from SDSS - VII. A catalogue of white dwarf-main sequence binaries

    NASA Astrophysics Data System (ADS)

    Rebassa-Mansergas, A.; Gänsicke, B. T.; Schreiber, M. R.; Koester, D.; Rodríguez-Gil, P.

    2010-02-01

    We present a catalogue of 1602 white-dwarf-main-sequence (WDMS) binaries from the spectroscopic Sloan Digital Sky Survey Data Release 6 (SDSS DR6). Among these, we identify 440 as new WDMS binaries. We select WDMS binary candidates by template fitting all 1.27 million DR6 spectra, using combined constraints in both χ2 and signal-to-noise ratio. In addition, we use Galaxy Evolution Explorer (GALEX) and UKIRT Infrared Sky Survey (UKIDSS) magnitudes to search for objects in which one of the two components dominates the SDSS spectrum. We use a decomposition/fitting technique to measure the effective temperatures, surface gravities, masses and distances to the white dwarfs, as well as the spectral types and distances to the companions in our catalogue. Distributions and density maps obtained from these stellar parameters are then used to study both the general properties and the selection effects of WDMS binaries in the SDSS. A comparison between the distances measured to the white dwarfs and the main-sequence companions shows dsec > dwd for approximately one-fifth of the systems, a tendency already found in our previous work. The hypothesis that magnetic activity raises the temperature of the inter-spot regions in active stars that are heavily covered by cool spots, leading to a bluer optical colour compared to inactive stars, remains the best explanation for this behaviour. We also make use of SDSS-GALEX-UKIDSS magnitudes to investigate the distribution of WDMS binaries, as well as their white-dwarf effective temperatures and companion star spectral types, in ultraviolet to infrared colour space. We show that WDMS binaries can be very efficiently separated from single main-sequence stars and white dwarfs when using a combined ultraviolet, optical and infrared colour selection. Finally, we also provide radial velocities for 1068 systems measured from the NaI λλ8183.27, 8194.81 absorption doublet and/or the Hα emission line. Among the systems with multiple SDSS

  18. Pulsed Accretion onto Eccentric and Circular Binaries

    NASA Astrophysics Data System (ADS)

    Muñoz, Diego J.; Lai, Dong

    2016-08-01

    We present numerical simulations of circumbinary accretion onto eccentric and circular binaries using the moving-mesh code AREPO. This is the first set of simulations to tackle the problem of binary accretion using a finite-volume scheme on a freely moving mesh, which allows for accurate measurements of accretion onto individual stars for arbitrary binary eccentricity. While accretion onto a circular binary shows bursts with period of ˜ 5 times the binary period P b, accretion onto an eccentric binary is predominantly modulated at the period ˜ 1{P}{{b}}. For an equal-mass circular binary, the accretion rates onto individual stars are quite similar to each other, following the same variable pattern in time. By contrast, for eccentric binaries, one of the stars can accrete at a rate 10-20 times larger than its companion. This “symmetry breaking” between the stars, however, alternates over timescales of order 200P b and can be attributed to a slowly precessing, eccentric circumbinary disk. Over longer timescales, the net accretion rates onto individual stars are the same, reaching a quasi-steady state with the circumbinary disk. These results have important implications for the accretion behavior of binary T Tauri stars and supermassive binary black holes.

  19. GALAXY ROTATION AND RAPID SUPERMASSIVE BINARY COALESCENCE

    SciTech Connect

    Holley-Bockelmann, Kelly; Khan, Fazeel Mahmood

    2015-09-10

    Galaxy mergers usher the supermassive black hole (SMBH) in each galaxy to the center of the potential, where they form an SMBH binary. The binary orbit shrinks by ejecting stars via three-body scattering, but ample work has shown that in spherical galaxy models, the binary separation stalls after ejecting all the stars in its loss cone—this is the well-known final parsec problem. However, it has been shown that SMBH binaries in non-spherical galactic nuclei harden at a nearly constant rate until reaching the gravitational wave regime. Here we use a suite of direct N-body simulations to follow SMBH binary evolution in both corotating and counterrotating flattened galaxy models. For N > 500 K, we find that the evolution of the SMBH binary is convergent and is independent of the particle number. Rotation in general increases the hardening rate of SMBH binaries even more effectively than galaxy geometry alone. SMBH binary hardening rates are similar for co- and counterrotating galaxies. In the corotating case, the center of mass of the SMBH binary settles into an orbit that is in corotation resonance with the background rotating model, and the coalescence time is roughly a few 100 Myr faster than a non-rotating flattened model. We find that counterrotation drives SMBHs to coalesce on a nearly radial orbit promptly after forming a hard binary. We discuss the implications for gravitational wave astronomy, hypervelocity star production, and the effect on the structure of the host galaxy.

  20. All Bright Cold Classical KBOs are Binary

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Parker, Alex H.; Grundy, William M.

    2014-11-01

    When sorted by absolute magnitude as seen in ground based observations, an extremely high fraction of the brightest Cold Classical (CC) Kuiper Belt objects (KBO) are, in fact resolved as binaries when observed at higher angular resolution. Of the 22 CCs brighter than H=6.1 observed by HST, 16 have been found to be binary yielding a binary fraction of 73±10%. When low inclination interlopers from the hot population and close binaries are considered, this very high fraction is consistent with 100% of bright CCs being binary. At fainter absolute magnitudes, this fraction drops to ~20%. Such a situation is a natural outcome of a broken size distribution with a steep drop-off in the number of CCs with individual component diameters larger than 150 km (for an assumed albedo of 0.15). A sharp cutoff in the size distribution for CCs is consistent with formation models that suggest that most planetesimals form at a preferred modal size of order 100 km.The very high fraction of binaries among the largest CCs also serves to limit the separation distribution of KBO binaries. At most, 27% of the brightest CCs are possible unresolved binaries. The apparent power law distribution of binary separation must cut off near the current observational limits of HST ( 1800 km at 43 AU). It is worth noting, however, that this observation does not constrain how many components of resolved binaries may themselves be unresolved multiples like 47171 1999 TC36. Finally, it is important to point out that, when sorted by the size of the primary rather than absolute magnitude of the unresolved pair, the fraction of binaries is relatively constant with size (Nesvorny et al. 2011, AJ 141, 159) eliminating observational bias as cause of the pile up of binaries among the brightest Cold Classical Kuiper Belt objects.The very high fraction of binaries among the brightest CCs appears to be an effect of the underlying CC size distribution.