Modeling perspectives on echolocation strategies inspired by bats flying in groups.

PubMed

Lin, Yuan; Abaid, Nicole

2015-12-21

Bats navigating with echolocation - which is a type of active sensing achieved by interpreting echoes resulting from self-generated ultrasonic pulses - exhibit unique behaviors during group flight. While bats may benefit from eavesdropping on their peers׳ echolocation, they also potentially suffer from confusion between their own and peers׳ pulses, caused by an effect called frequency jamming. This hardship of group flight is supported by experimental observations of bats simplifying their sound-scape by shifting their pulse frequencies or suppressing echolocation altogether. Here, we investigate eavesdropping and varying pulse emission rate from a modeling perspective to understand these behaviors׳ potential benefits and detriments. We define an agent-based model of echolocating bats avoiding collisions in a three-dimensional tunnel. Through simulation, we show that bats with reasonably accurate eavesdropping can reduce collisions compared to those neglecting information from peers. In large populations, bats minimize frequency jamming by decreasing pulse emission rate, while collision risk increases; conversely, increasing pulse emission rate minimizes collisions by allowing more sensing information generated per bat. These strategies offer benefits for both biological and engineered systems, since frequency jamming is a concern in systems using active sensing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Configuration-specific kinetic theory applied to an ideal binary gas mixture.

PubMed

Wiseman, Floyd L

2006-10-05

This paper is the second in a two-part series dealing with the configuration-specific analyses for molecular collision events of hard, spherical molecules at thermal equilibrium. The first paper analyzed a single-component system, and the reader is referred to it for the fundamental concepts. In this paper, the expressions for the configuration-specific collision frequencies and the average line-of-centers collision angles and speeds are derived for an ideal binary gas mixture. The analyses show that the average line-of-centers quantities are all dependent upon the ratio of the masses of the two components, but not upon molecular size. Of course, the configuration-specific collision frequencies do depend on molecular size. The expression for the overall binary collision frequency is a simple sum of the configuration-specific collision frequencies and is identical to the conventional expression.

Research on the FDTD method of scattering effects of obliquely incident electromagnetic waves in time-varying plasma sheath on collision and plasma frequencies

NASA Astrophysics Data System (ADS)

Chen, Wei; Guo, Li-xin; Li, Jiang-ting

2017-04-01

This study analyzes the scattering characteristics of obliquely incident electromagnetic (EM) waves in a time-varying plasma sheath. The finite-difference time-domain algorithm is applied. According to the empirical formula of the collision frequency in a plasma sheath, the plasma frequency, temperature, and pressure are assumed to vary with time in the form of exponential rise. Some scattering problems of EM waves are discussed by calculating the radar cross section (RCS) of the time-varying plasma. The laws of the RCS varying with time are summarized at the L and S wave bands.

Electron-ion collision rates in noble gas clusters irradiated by femtosecond laser pulse

NASA Astrophysics Data System (ADS)

Dey, R.; Roy, A. C.

2012-05-01

We report a theoretical analysis of electron-ion collision rates in xenon gas clusters irradiated by femtosecond laser pulses. The present analysis is based on the eikonal approximation (EA), the first Born approximation (FBA) and the classical (CL) methods. The calculations are performed using the plasma-screened Rogers potential introduced by Moll et al. [J. Phys. B. 43, 135103 (2010)] as well as the Debye potential for a wide range of experimental parameters. We find that the magnitudes of electron-ion collision frequency obtained in the EA do not fall as rapidly with the kinetic energy of electrons as in the FBA and CL methods for higher charge states of xenon ion (Xe8+ and Xe14+). Furthermore, EA shows that the effect of the inner structure of ion is most dominant for the lowest charge state of xenon ion (Xe1+). In the case of the present effective potential, FBA overestimates the CL results for all three different charge states of xenon, whereas for the Debye potential, both the FBA and CL methods predict collision frequencies which are nearly close to each other.

A rapid method of estimating the collision frequencies between the earth and the earth-crossing bodies

NASA Technical Reports Server (NTRS)

Su, Shin-Yi; Kessler, Donald J.

1991-01-01

The present study examines a very fast method of calculating the collision frequency between two low-eccentricity orbiting bodies for evaluating the evolution of earth-orbiting objects such as space debris. The results are very accurate and the required computer time is negligible. The method is now applied without modification to calculate the collision frequencies for moderately and highly eccentric orbits.

Modeling Forces and Moments at the Base of a Rat Vibrissa during Noncontact Whisking and Whisking against an Object

PubMed Central

Quist, Brian W.; Seghete, Vlad; Huet, Lucie A.; Murphey, Todd D.

2014-01-01

During exploratory behavior, rats brush and tap their whiskers against objects, and the mechanical signals so generated constitute the primary sensory variables upon which these animals base their vibrissotactile perception of the world. To date, however, we lack a general dynamic model of the vibrissa that includes the effects of inertia, damping, and collisions. We simulated vibrissal dynamics to compute the time-varying forces and bending moment at the vibrissa base during both noncontact (free-air) whisking and whisking against an object (collision). Results show the following: (1) during noncontact whisking, mechanical signals contain components at both the whisking frequency and also twice the whisking frequency (the latter could code whisking speed); (2) when rats whisk rhythmically against an object, the intrinsic dynamics of the vibrissa can be as large as many of the mechanical effects of the collision, however, the axial force could still generate responses that reliably indicate collision based on thresholding; and (3) whisking velocity will have only a small effect on the transient response generated during a whisker–object collision. Instead, the transient response will depend in large part on how the rat chooses to decelerate its vibrissae after the collision. The model allows experimentalists to estimate error bounds on quasi-static descriptions of vibrissal shape, and its predictions can be used to bound realistic expectations from neurons that code vibrissal sensing. We discuss the implications of these results under the assumption that primary sensory neurons of the trigeminal ganglion are sensitive to various combinations of mechanical signals. PMID:25057187

Frequency of extreme weather events and increased risk of motor vehicle collision in Maryland.

PubMed

Liu, Ann; Soneja, Sutyajeet I; Jiang, Chengsheng; Huang, Chanjuan; Kerns, Timothy; Beck, Kenneth; Mitchell, Clifford; Sapkota, Amir

2017-02-15

Previous studies have shown increased precipitation to be associated with higher frequency of traffic collisions. However, data regarding how extreme weather events, projected to grow in frequency, intensity, and duration in response to a changing climate, might affect the risk of motor vehicle collisions is particularly limited. We investigated the association between frequency of extreme heat and precipitation events and risk of motor vehicle collision in Maryland between 2000 and 2012. Motor vehicle collision data was obtained from the Maryland Automated Accident Reporting System. Each observation in the data set corresponded to a unique collision event. This data was linked to extreme heat and precipitation events that were calculated using location and calendar day specific thresholds. A time-stratified case-crossover analysis was utilized to assess the association between exposure to extreme heat and precipitation events and risk of motor vehicle collision. Additional stratified analyses examined risk by road condition, season, and collisions involving only one vehicle. Overall, there were over 1.28 million motor vehicle collisions recorded in Maryland between 2000 and 2012, of which 461,009 involved injuries or death. There was a 23% increase in risk of collision for every 1-day increase in extreme precipitation event (Odds Ratios (OR) 1.23, 95% Confidence Interval (CI): 1.22, 1.27). This risk was considerably higher for collisions on roads with a defect or obstruction (OR: 1.46, 95% CI: 1.40, 1.52) and those involving a single vehicle (OR: 1.41, 95% CI: 1.39, 1.43). Change in risk associated with extreme heat events was marginal at best. Extreme precipitation events are associated with an increased risk of motor vehicle collisions in Maryland. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of YORP-induced rotational fission on the small size end of the Main Belt asteroid size distribution

NASA Astrophysics Data System (ADS)

Rossi, Alessandro; Jacobson, S.; Marzari, F.; Scheeres, D.; Davis, D. R.

2013-10-01

From the results of a comprehensive asteroid population evolution model, we conclude that the YORP-induced rotational fission hypothesis has strong repercussions for the small size end of the Main Belt asteroid size frequency distribution. These results are consistent with observed asteroid population statistics. The foundation of this model is the asteroid rotation model of Marzari et al. (2011), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur). The YORP effect timescale for large asteroids with diameters D > ~6 km is longer than the collision timescale in the Main Belt, thus the frequency of large asteroids is determined by a collisional equilibrium (e.g. Bottke 2005), but for small asteroids with diameters D < ~6 km, the asteroid population evolution model confirms that YORP-induced rotational fission destroys small asteroids more frequently than collisions. Therefore, the frequency of these small asteroids is determined by an equilibrium between the creation of new asteroids out of the impact debris of larger asteroids and the destruction of these asteroids by YORP-induced rotational fission. By introducing a new source of destruction that varies strongly with size, YORP-induced rotational fission alters the slope of the size frequency distribution. Using the outputs of the asteroid population evolution model and a 1-D collision evolution model, we can generate this new size frequency distribution and it matches the change in slope observed by the SKADS survey (Gladman 2009). This agreement is achieved with both an accretional power-law or a truncated “Asteroids were Born Big” size frequency distribution (Weidenschilling 2010, Morbidelli 2009).

Patterns of bird-window collisions inform mitigation on a university campus

PubMed Central

Winton, R. Scott; Wu, Charlene J.; Zambello, Erika; Wittig, Thomas W.; Cagle, Nicolette L.

2016-01-01

Bird-window collisions cause an estimated one billion bird deaths annually in the United States. Building characteristics and surrounding habitat affect collision frequency. Given the importance of collisions as an anthropogenic threat to birds, mitigation is essential. Patterned glass and UV-reflective films have been proven to prevent collisions. At Duke University’s West campus in Durham, North Carolina, we set out to identify the buildings and building characteristics associated with the highest frequencies of collisions in order to propose a mitigation strategy. We surveyed six buildings, stratified by size, and measured architectural characteristics and surrounding area variables. During 21 consecutive days in spring and fall 2014, and spring 2015, we conducted carcass surveys to document collisions. In addition, we also collected ad hoc collision data year-round and recorded the data using the app iNaturalist. Consistent with previous studies, we found a positive relationship between glass area and collisions. Fitzpatrick, the building with the most window area, caused the most collisions. Schwartz and the Perk, the two small buildings with small window areas, had the lowest collision frequencies. Penn, the only building with bird deterrent pattern, caused just two collisions, despite being almost completely made out of glass. Unlike many research projects, our data collection led to mitigation action. A resolution supported by the student government, including news stories in the local media, resulted in the application of a bird deterrent film to the building with the most collisions: Fitzpatrick. We present our collision data and mitigation result to inspire other researchers and organizations to prevent bird-window collisions. PMID:26855877

Using GPS telemetry to determine roadways most susceptible to deer-vehicle collisions

USGS Publications Warehouse

Kramer, David W.; Prebyl, Thomas J.; Stickles, James H.; Osborn, David A.; Irwin, Brian J.; Nibbelink, Nathan P.; Warren, Robert J.; Miller, Karl V.

2016-01-01

More than 1 million wildlife-vehicle collisions occur annually in the United States. The majority of these accidents involve white-tailed deer (Odocoileus virginianus) and result in >US $4.6 billion in damage and >200 human fatalities. Prior research has used collision locations to assess sitespecific as well as landscape features that contribute to risk of deer-vehicle collisions. As an alternative approach, we calculated road-crossing locations from 25 GPS-instrumented white-tailed deer near Madison, Georgia (n=154,131 hourly locations). We identified crossing locations by creating movement paths between subsequent GPS points and then intersecting the paths with road locations. Using AIC model selection, we determined whether 10 local and landscape variables were successful at identifying areas where higher frequencies of deer crossings were likely to occur. Our findings indicate that traffic volume, distance to riparian areas, and the amount of forested area influenced the frequency of road crossings. Roadways that were predominately located in wooded landscapes and 200–300 m from riparian areas were crossed frequently. Additionally, we found that areas of low traffic volume (e.g., county roads) had the highest frequencies of deer crossings. Analyses utilizing only records of deer-vehicle collision locations cannot separate the relative contribution of deer crossing rates and traffic volume. Increased frequency of road crossings by deer in low-traffic, forested areas may lead to a greater risk of deer-vehicle collision than suggested by evaluations of deer-vehicle collision frequency alone.

Electronic transport coefficients in plasmas using an effective energy-dependent electron-ion collision-frequency

NASA Astrophysics Data System (ADS)

Faussurier, G.; Blancard, C.; Combis, P.; Decoster, A.; Videau, L.

2017-10-01

We present a model to calculate the electrical and thermal electronic conductivities in plasmas using the Chester-Thellung-Kubo-Greenwood approach coupled with the Kramers approximation. The divergence in photon energy at low values is eliminated using a regularization scheme with an effective energy-dependent electron-ion collision-frequency. Doing so, we interpolate smoothly between the Drude-like and the Spitzer-like regularizations. The model still satisfies the well-known sum rule over the electrical conductivity. Such kind of approximation is also naturally extended to the average-atom model. A particular attention is paid to the Lorenz number. Its nondegenerate and degenerate limits are given and the transition towards the Drude-like limit is proved in the Kramers approximation.

Super-resolution imaging based on the temperature-dependent electron-phonon collision frequency effect of metal thin films

NASA Astrophysics Data System (ADS)

Ding, Chenliang; Wei, Jingsong; Xiao, Mufei

2018-05-01

We herein propose a far-field super-resolution imaging with metal thin films based on the temperature-dependent electron-phonon collision frequency effect. In the proposed method, neither fluorescence labeling nor any special properties are required for the samples. The 100 nm lands and 200 nm grooves on the Blu-ray disk substrates were clearly resolved and imaged through a laser scanning microscope of wavelength 405 nm. The spot size was approximately 0.80 μm , and the imaging resolution of 1/8 of the laser spot size was experimentally obtained. This work can be applied to the far-field super-resolution imaging of samples with neither fluorescence labeling nor any special properties.

Effects of velocity-changing collisions on two-photon and stepwise-absorption spectroscopic line shapes

NASA Astrophysics Data System (ADS)

Liao, P. F.; Bjorkholm, J. E.; Berman, P. R.

1980-06-01

We report the results of an experimental study of the effects of velocity-changing collisions on two-photon and stepwise-absorption line shapes. Excitation spectra for the 3S12-->3P12-->4D12 transitions of sodium atoms undergoing collisions with foreign gas perturbers are obtained. These spectra are obtained with two cw dye lasers. One laser, the pump laser, is tuned 1.6 GHz below the 3S12-->3P12 transition frequency and excites a nonthermal longitudinal velocity distribution of excited 3P12 atoms in the vapor. Absorption of the second (probe) laser is used to monitor the steady-state excited-state distribution which is a result of collisions with rare gas atoms. The spectra are obtained for various pressures of He, Ne, and Kr gases and are fit to a theoretical model which utilizes either the phenomenological Keilson-Störer or the classical hardsphere collision kernel. The theoretical model includes the effects of collisionally aided excitation of the 3P12 state as well as effects due to fine-structure state-changing collisions. Although both kernels are found to predict line shapes which are in reasonable agreement with the experimental results, the hard-sphere kernel is found superior as it gives a better description of the effects of large-angle scattering for heavy perturbers. Neither kernel provides a fully adequate description over the entire line profile. The experimental data is used to extract effective hard-sphere collision cross sections for collisions between sodium 3P12 atoms and helium, neon, and krypton perturbers.

2005 annual state highway collision data summary

DOT National Transportation Integrated Search

2006-01-01

This report covers collisions on all State Highways in Washington State for the year 2005. Tables and charts will be used to show frequency and rate of : collisions, multi-year trends, collision types, contributing circumstances and other factors. : ...

2004 annual state highway collision data summary

DOT National Transportation Integrated Search

2006-01-01

This report covers collisions on all State Highways in Washington State for the year 2004. Tables and charts will be used to show frequency and rate of : collisions, multi-year trends, collision types, contributing circumstances and other factors. : ...

2006 Washington State collision data summary : highways only

DOT National Transportation Integrated Search

2007-01-01

This report covers collisions on all State Highways (includes Interstates and State Highways only) in Washington State for the year 2006. : Tables and charts show frequency and rate of collisions, multi-year trends, collision types, contributing circ...

Mathematical Model for Collision-Coalescence Among Inclusions in the Bloom Continuous Caster with M-EMS

NASA Astrophysics Data System (ADS)

Lei, Hong; Jiang, Jimin; Yang, Bin; Zhao, Yan; Zhang, Hongwei; Wang, Weixian; Dong, Guiwen

2018-04-01

Mathematical simulation is an effective tool to analyze the fluid flow and the inclusion behavior in the bloom continuous caster with mold electromagnetic stirring (M-EMS). The mathematical model is applied to the modeling of magnetic field, flow field, and inclusion field. Due to the introduction of Archimedes force, the collision mechanism and inclusion's slipping velocity should be modified in the inclusion mass and population conservation model. Numerically predicted magnetic field, flow field, and the inclusion spatial distribution conform to the experimental results in the existing literature. Lorentz force plays an important role in the fluid flow, and Archimedes force plays an important role in the inclusion distribution in the continuous caster. Due to Brownian collision, Stokes collision, Archimedes collision, and turbulent collision, the coalescence among inclusions occurs in the bloom continuous caster with M-EMS. Among the four types of collisions, turbulent collision occurs most frequently, followed by Archimedes collision and Stokes collision. The frequency of Brownian collision is several orders of magnitudes smaller and is therefore negligible. The inclusion volume concentration, number density, and characteristic radius exhibit a U-shape in the continuous caster without M-EMS. However, with M-EMS, they exhibit an inverted U-shape.

Radio Frequency Electromagnetic Radiation From Streamer Collisions

NASA Astrophysics Data System (ADS)

Luque, Alejandro

2017-10-01

We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz. We also investigate the fast penetration, after a collision, of electromagnetic fields into the streamer heads and show that these fields are capable of accelerating electrons up to about 100 keV. By substantiating the link between X-rays and high-frequency radio emissions and by describing a mechanism for the early acceleration of runaway electrons, our results support the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges.

Radio Frequency Electromagnetic Radiation From Streamer Collisions.

PubMed

Luque, Alejandro

2017-10-16

We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz. We also investigate the fast penetration, after a collision, of electromagnetic fields into the streamer heads and show that these fields are capable of accelerating electrons up to about 100 keV. By substantiating the link between X-rays and high-frequency radio emissions and by describing a mechanism for the early acceleration of runaway electrons, our results support the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges.

Analytical Proof That There is no Effect of Confinement or Curvature on the Maxwell-Boltzmann Collision Frequency

NASA Astrophysics Data System (ADS)

Carnio, Brett N.; Elliott, Janet A. W.

2014-08-01

The number of Maxwell-Boltzmann particles that hit a flat wall in infinite space per unit area per unit time is a well-known result. As new applications are arising in micro and nanotechnologies there are a number of situations in which a rarefied gas interacts with either a flat or curved surface in a small confined geometry. Thus, it is necessary to prove that the Maxwell-Boltzmann collision frequency result holds even if a container's dimensions are on the order of nanometers and also that this result is valid for both a finite container with flat walls (a rectangular container) and a finite container with a curved wall (a cylindrical container). An analytical proof confirms that the Maxwell-Boltzmann collision frequencies for either a finite rectangular container or a finite cylindrical container are both equal to the well-known result obtained for a flat wall in infinite space. A major aspect of this paper is the introduction of a mathematical technique to solve the arising infinite sum of integrals whose integrands depend on the Maxwell-Boltzmann velocity distribution.

Instantaneous polarization statistic property of EM waves incident on time-varying reentry plasma

NASA Astrophysics Data System (ADS)

Bai, Bowen; Liu, Yanming; Li, Xiaoping; Yao, Bo; Shi, Lei

2018-06-01

An analytical method is proposed in this paper to study the effect of time-varying reentry plasma sheath on the instantaneous polarization statistic property of electromagnetic (EM) waves. Based on the disturbance property of the hypersonic fluid, the spatial-temporal model of the time-varying reentry plasma sheath is established. An analytical technique referred to as transmission line analogy is developed to calculate the instantaneous transmission coefficient of EM wave propagation in time-varying plasma. Then, the instantaneous polarization statistic theory of EM wave propagation in the time-varying plasma sheath is developed. Taking the S-band telemetry right hand circularly polarized wave as an example, effects of incident angle and plasma parameters, including the electron density and the collision frequency on the EM wave's polarization statistic property are studied systematically. Statistical results indicate that the lower the collision frequency and the larger the electron density and incident angle is, the worse the deterioration of the polarization property is. Meanwhile, in conditions of critical parameters of certain electron density, collision frequency, and incident angle, the transmitted waves have both the right and left hand polarization mode, and the polarization mode will reverse. The calculation results could provide useful information for adaptive polarization receiving of the spacecraft's reentry communication.

Collision frequency of artificial satellites - The creation of a debris belt

NASA Technical Reports Server (NTRS)

Kessler, D. J.; Cour-Palais, B. G.

1978-01-01

The probability of satellite collisions increases with the number of satellites. In the present paper, possible time scales for the growth of a debris belt from collision fragments are determined, and possible consequences of continued unrestrained launch activities are examined. Use is made of techniques formerly developed for studying the evolution (growth) of the asteroid belt. A model describing the flux from the known earth-orbiting satellites is developed, and the results from this model are extrapolated in time to predict the collision frequency between satellites. Hypervelocity impact phenomena are then examined to predict the debris flux resulting from collisions. The results are applied to design requirements for three types of future space missions.

TURBULENCE-INDUCED RELATIVE VELOCITY OF DUST PARTICLES. IV. THE COLLISION KERNEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Liubin; Padoan, Paolo, E-mail: lpan@cfa.harvard.edu, E-mail: ppadoan@icc.ub.edu

Motivated by its importance for modeling dust particle growth in protoplanetary disks, we study turbulence-induced collision statistics of inertial particles as a function of the particle friction time, τ{sub p}. We show that turbulent clustering significantly enhances the collision rate for particles of similar sizes with τ{sub p} corresponding to the inertial range of the flow. If the friction time, τ{sub p,} {sub h}, of the larger particle is in the inertial range, the collision kernel per unit cross section increases with increasing friction time, τ{sub p,} {sub l}, of the smaller particle and reaches the maximum at τ{sub p,}more » {sub l} = τ{sub p,} {sub h}, where the clustering effect peaks. This feature is not captured by the commonly used kernel formula, which neglects the effect of clustering. We argue that turbulent clustering helps alleviate the bouncing barrier problem for planetesimal formation. We also investigate the collision velocity statistics using a collision-rate weighting factor to account for higher collision frequency for particle pairs with larger relative velocity. For τ{sub p,} {sub h} in the inertial range, the rms relative velocity with collision-rate weighting is found to be invariant with τ{sub p,} {sub l} and scales with τ{sub p,} {sub h} roughly as ∝ τ{sub p,h}{sup 1/2}. The weighting factor favors collisions with larger relative velocity, and including it leads to more destructive and less sticking collisions. We compare two collision kernel formulations based on spherical and cylindrical geometries. The two formulations give consistent results for the collision rate and the collision-rate weighted statistics, except that the spherical formulation predicts more head-on collisions than the cylindrical formulation.« less

Nonextensive statistics and skin depth of transverse wave in collisional plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashemzadeh, M., E-mail: hashemzade@gmail.com

Skin depth of transverse wave in a collisional plasma is studied taking into account the nonextensive electron distribution function. Considering the kinetic theory for charge particles and using the Bhatnagar-Gross-Krook collision model, a generalized transverse dielectric permittivity is obtained. The transverse dispersion relation in different frequency ranges is investigated. Obtaining the imaginary part of the wave vector from the dispersion relation, the skin depth for these frequency ranges is also achieved. Profiles of the skin depth show that by increasing the q parameter, the penetration depth decreases. In addition, the skin depth increases by increasing the electron temperature. Finally, itmore » is found that in the high frequency range and high electron temperature, the penetration depth decreases by increasing the collision frequency. In contrast, by increasing the collision frequency in a highly collisional frequency range, the skin depth of transverse wave increases.« less

Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

DOE PAGES

Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; ...

2015-08-04

Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Importantmore » swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections.« less

Power Dependence of the Electron Mobility Profile in a Hall Thruster

NASA Technical Reports Server (NTRS)

Jorns, Benjamin A.; Hofery, Richard H.; Mikellides, Ioannis G.

2014-01-01

The electron mobility profile is estimated in a 4.5 kW commercial Hall thruster as a function of discharge power. Internal measurements of plasma potential and electron temperature are made in the thruster channel with a high-speed translating probe. These measurements are presented for a range of throttling conditions from 150 - 400 V and 0.6 - 4.5 kW. The fluid-based solver, Hall2De, is used in conjunction with these internal plasma parameters to estimate the anomalous collision frequency profile at fixed voltage, 300 V, and three power levels. It is found that the anomalous collision frequency profile does not change significantly upstream of the location of the magnetic field peak but that the extent and magnitude of the anomalous collision frequency downstream of the magnetic peak does change with thruster power. These results are discussed in the context of developing phenomenological models for how the collision frequency profile depends on thruster operating conditions.

Nonlinear regime of electrostatic waves propagation in presence of electron-electron collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezzi, Oreste; Valentini, Francesco; Veltri, Pierluigi

2015-04-15

The effects are presented of including electron-electron collisions in self-consistent Eulerian simulations of electrostatic wave propagation in nonlinear regime. The electron-electron collisions are approximately modeled through the full three-dimensional Dougherty collisional operator [J. P. Dougherty, Phys. Fluids 7, 1788 (1964)]; this allows the elimination of unphysical byproducts due to reduced dimensionality in velocity space. The effects of non-zero collisionality are discussed in the nonlinear regime of the symmetric bump-on-tail instability and in the propagation of the so-called kinetic electrostatic electron nonlinear (KEEN) waves [T. W. Johnston et al., Phys. Plasmas 16, 042105 (2009)]. For both cases, it is shown howmore » collisions work to destroy the phase-space structures created by particle trapping effects and to damp the wave amplitude, as the system returns to the thermal equilibrium. In particular, for the case of the KEEN waves, once collisions have smoothed out the trapped particle population which sustains the KEEN fluctuations, additional oscillations at the Langmuir frequency are observed on the fundamental electric field spectral component, whose amplitude decays in time at the usual collisionless linear Landau damping rate.« less

Analytic non-Maxwellian electron velocity distribution function in a Hall discharge plasma

NASA Astrophysics Data System (ADS)

Shagayda, Andrey; Tarasov, Alexey

2017-10-01

The electron velocity distribution function in the low-pressure discharges with the crossed electric and magnetic fields, which occur in magnetrons, plasma accelerators, and Hall thrusters with a closed electron drift, is not Maxwellian. A deviation from equilibrium is caused by a large electron mean free path relative to the Larmor radius and the size of the discharge channel. In this study, we derived in the relaxation approximation the analytical expression of the electron velocity distribution function in a weakly ionized Lorentz plasma with the crossed electric and magnetic fields in the presence of the electron density and temperature gradients in the direction of the electric field. The solution was obtained in the stationary approximation far from boundary surfaces, when diffusion and mobility are determined by the classical effective collision frequency of electrons with ions and atoms. The moments of the distribution function including the average velocity, the stress tensor, and the heat flux were calculated and compared with the classical hydrodynamic expressions. It was shown that a kinetic correction to the drift velocity stems from a contribution of the off-diagonal component of the stress tensor. This correction becomes essential if the drift velocity in the crossed electric and magnetic fields would be comparable to the thermal velocity of electrons. The electron temperature has three different components at a nonzero effective collision frequency and two different components in the limit when the collision frequency tends to zero. It is shown that, in the presence of ionization collisions, the components of the heat flux have additives that are not related to the temperature gradient, and arise because of the electron drift.

Electromagnetic wave energy flow control with a tunable and reconfigurable coupled plasma split-ring resonator metamaterial: A study of basic conditions and configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kourtzanidis, Konstantinos, E-mail: kkourt@utexas.edu; Pederson, Dylan M.; Raja, Laxminarayan L.

2016-05-28

We propose and study numerically a tunable and reconfigurable metamaterial based on coupled split-ring resonators (SRRs) and plasma discharges. The metamaterial couples the magnetic-electric response of the SRR structure with the electric response of a controllable plasma slab discharge that occupies a volume of the metamaterial. Because the electric response of a plasma depends on its constitutive parameters (electron density and collision frequency), the plasma-based metamaterial is tunable and active. Using three-dimensional numerical simulations, we analyze the coupled plasma-SRR metamaterial in terms of transmittance, performing parametric studies on the effects of electron density, collisional frequency, and the position of themore » plasma slab with respect to the SRR array. We find that the resonance frequency can be controlled by the plasma position or the plasma-to-collision frequency ratio, while transmittance is highly dependent on the latter.« less

Radio-Frequency-Controlled Cold Collisions and Universal Properties of Unitary Bose Gases

NASA Astrophysics Data System (ADS)

Ding, Yijue

This thesis investigates two topics: ultracold atomic collisions in a radio-frequency field and universal properties of a degenerate unitary Bose gas. One interesting point of the unitary Bose gas is that the system has only one length scale, that is, the average interparticle distance. This single parameter determines all properties of the gas, which is called the universality of the system. We first introduce a renormalized contact interaction to extend the validity of the zero-range interaction to large scattering lengths. Then this renormalized interaction is applied to many-body theories to determined those universal relations of the system. From the few-body perspective, we discuss the scattering between atoms in a single-color radio-frequency field. Our motivation is proposing the radio-frequency field as an effective tool to control interactions between cold atoms. Such a technique may be useful in future experiments such as creating phase transitions in spinor condensates. We also discuss the formation of ultracold molecules using radio-freqency fields from a time-dependent approach.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bondarenko, A. S., E-mail: AntonBondarenko@ymail.com; Schaeffer, D. B.; Everson, E. T.

The collision-less transfer of momentum and energy from explosive debris plasma to magnetized background plasma is a salient feature of various astrophysical and space environments. While much theoretical and computational work has investigated collision-less coupling mechanisms and relevant parameters, an experimental validation of the results demands the measurement of the complex, collective electric fields associated with debris-background plasma interaction. Emission spectroscopy offers a non-interfering diagnostic of electric fields via the Stark effect. A unique experiment at the University of California, Los Angeles, that combines the Large Plasma Device (LAPD) and the Phoenix laser facility has investigated the marginally super-Alfvénic, quasi-perpendicularmore » expansion of a laser-produced carbon (C) debris plasma through a preformed, magnetized helium (He) background plasma via emission spectroscopy. Spectral profiles of the He II 468.6 nm line measured at the maximum extent of the diamagnetic cavity are observed to intensify, broaden, and develop equally spaced modulations in response to the explosive C debris, indicative of an energetic electron population and strong oscillatory electric fields. The profiles are analyzed via time-dependent Stark effect models corresponding to single-mode and multi-mode monochromatic (single frequency) electric fields, yielding temporally resolved magnitudes and frequencies. The proximity of the measured frequencies to the expected electron plasma frequency suggests the development of the electron beam-plasma instability, and a simple saturation model demonstrates that the measured magnitudes are feasible provided that a sufficiently fast electron population is generated during C debris–He background interaction. Potential sources of the fast electrons, which likely correspond to collision-less coupling mechanisms, are briefly considered.« less

Collision attack against Tav-128 hash function

NASA Astrophysics Data System (ADS)

Hariyanto, Fajar; Hayat Susanti, Bety

2017-10-01

Tav-128 is a hash function which is designed for Radio Frequency Identification (RFID) authentication protocol. Tav-128 is expected to be a cryptographically secure hash function which meets collision resistance properties. In this research, a collision attack is done to prove whether Tav-128 is a collision resistant hash function. The results show that collisions can be obtained in Tav-128 hash function which means in other word, Tav-128 is not a collision resistant hash function.

Temporal characteristics of electrostatic surface waves in a cold complex plasma containing collision-dominated ion flow

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-03-01

The influence of electron-ion collision frequency and dust charge on the growth rate of two-stream instability of the electrostatic surface wave propagating at the interface of semi-infinite complex plasma whose constituents are electrons, negatively charged dust, and streaming ions. It is found that the surface wave can be unstable if the multiplication of wave number and ion flow velocity is greater than the total plasma frequency of electrons and dusts. The analytical solution of the growth rate is derived as a function of collision frequency, dust charge, and ion-to-electron density ratio. It is found that the growth rate is inversely proportional to the collision rate, but it is enhanced as the number of electrons residing on the dust grain surface is increased. The growth rate of surface wave is compared to that of the bulk wave.

Comparison of collision operators for the geodesic acoustic mode

NASA Astrophysics Data System (ADS)

Li, Yang; Gao, Zhe

2015-04-01

The collisional damping rate and real frequency of the geodesic acoustic mode (GAM) are solved from a drift kinetic model with different collision operators. As the ion collision rate increases, the damping rate increases at low collision rate but decays at high ion collision rate. Different collision operators do not change the overall trend but influence the magnitude of the damping rate. The collision damping is much overestimated with the number-conserving-only Krook operator; on the other hand, using the Lorentz operator with a constant collision rate, the damping is overestimated at low collision rate but underestimated at high collision rate. The results from the Krook operator with both number and energy conservation terms, the Lorentz operator with an energy-dependent collision rate and the full Hirshman-Sigmar-Clarke collision operator are very close. Meanwhile, as the ion collision rate increases, the GAM frequency decreases from the collisionless value, \\sqrt {7/4+τ} {vti}/R , to \\sqrt {1+τ} {vti}/R for the number-conserving-only Krook operator, but to \\sqrt {5/3+τ} {vti}/R for the other four operators, which conserve both number and energy, where τ, vti and R are the ratio of electron temperature to ion temperature, the ion thermal velocity and the major radius, respectively. The results imply that the property of energy conservation of the collision operator is important to the dynamics of the GAM as well as that of number conservation, which may provide guidance in choosing collision operators in further study of the zonal flow (ZF) dynamics, such as the nonlinear simulation of the ZF-turbulence system.

Low-frequency Carbon Radio Recombination Lines. I. Calculations of Departure Coefficients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salgado, F.; Morabito, L. K.; Oonk, J. B. R.

In the first paper of this series, we study the level population problem of recombining carbon ions. We focus our study on high quantum numbers, anticipating observations of carbon radio recombination lines to be carried out by the Low Frequency Array. We solve the level population equation including angular momentum levels with updated collision rates up to high principal quantum numbers. We derive departure coefficients by solving the level population equation in the hydrogenic approximation and including low-temperature dielectronic capture effects. Our results in the hydrogenic approximation agree well with those of previous works. When comparing our results including dielectronicmore » capture, we find differences that we ascribe to updates in the atomic physics (e.g., collision rates) and to the approximate solution method of the statistical equilibrium equations adopted in previous studies. A comparison with observations is discussed in an accompanying article, as radiative transfer effects need to be considered.« less

Effects of Ion-ion Collisions and Inhomogeneity in Two-dimensional Simulations of Stimulated Brillouin Backscattering*

NASA Astrophysics Data System (ADS)

Cohen, B. I.

2005-10-01

Two-dimensional simulations of stimulated Brillouin backscattering (SBBS) with the BZOHAR^1 code have been extended to include ion-ion collisions and spatial nonuniformity in the mean ion flow. BZOHAR hybrid simulations (particle-in-cell kinetic ions and Boltzmann fluid electrons) have shown^2 that SBBS saturation is dominated by ion trapping effects and secondary instability of the primary ion wave (decay into subharmonic ion waves and ion quasi-modes). Here we address the effects of ion collisions^3 on SBBS saturation and employ the efficient Langevin ion collision algorithm of Ref. 4 and the Fokker-Planck collision operator of Ref. 5. We also report simulations of SBBS with a linear gradient in the mean ion drift, which in conjunction with the nonlinear frequency shift due to ion trapping can introduce auto-resonance effects that may enhance reflectivities.^6 For SBBS in a high-gain limit with ion collisions or inhomogeneity, we find that ion trapping and secondary ion wave instabilities are robust saturation mechanisms. *Work performed for US DOE by UC LLNL under Contr. W-7405-ENG-48. ^1B.I. Cohen, et al., Phys. Plasmas 4, 956 (1997). ^2B.I. Cohen, et al., Phys. Plasmas, 12, 052703 (2005),. ^ 3P.W. Rambo, et al., Phys. Rev. Lett. 79, 83 (1997). ^ 4M.E. Jones, et al., J. Comp. Phys. 123, 169, (1996). ^ 5W. M. Manheimer, et al., J. Comp. Phys. 138, 563 (1997). ^ 6E.A. Williams, et al., Phys. Plasmas 11, 231 (2004).

Sweet's mechanism in the solar wind

NASA Technical Reports Server (NTRS)

Burlaga, L. F.; Scudder, J. D.

1974-01-01

Sweet's mechanism occurs in the solar wind, at D-sheets near 1 AU. Conductivities on the order of 10,000 esu are obtained, which is on the order of the local plasma frequency. This implies that the effective collision frequency is on the order of the plasma frequency. The lateral extent of D-sheets is approximately 0.01 AU to 0.001 AU. Hundreds of such D-sheets are probably present between the orbits of Venus and Earth at any instant.

Proton stopping using a full conserving dielectric function in plasmas at any degeneracy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barriga-Carrasco, Manuel D.

2010-10-15

In this work, we present a dielectric function including the three conservation laws (density, momentum and energy) when we take into account electron-electron collisions in a plasma at any degeneracy. This full conserving dielectric function (FCDF) reproduces the random phase approximation (RPA) and Mermin ones, which confirms this outcome. The FCDF is applied to the determination of the proton stopping power. Differences among diverse dielectric functions in the proton stopping calculation are minimal if the plasma electron collision frequency is not high enough. These discrepancies can rise up to 2% between RPA values and the FCDF ones, and to 8%more » between the Mermin ones and FCDF ones. The similarity between RPA and FCDF results is not surprising, as all conservation laws are also considered in RPA dielectric function. Even for plasmas with low collision frequencies, those discrepancies follow the same behavior as for plasmas with higher frequencies. Then, discrepancies do not depend on the plasma degeneracy but essentially do on the value of the plasma collision frequency.« less

Collisions of ideal gas molecules with a rough/fractal surface. A computational study.

PubMed

Panczyk, Tomasz

2007-02-01

The frequency of collisions of ideal gas molecules (argon) with a rough surface has been studied. The rough/fractal surface was created using random deposition technique. By applying various depositions, the roughness of the surface was controlled and, as a measure of the irregularity, the fractal dimensions of the surfaces were determined. The surfaces were next immersed in argon (under pressures 2 x 10(3) to 2 x 10(5) Pa) and the numbers of collisions with these surfaces were counted. The calculations were carried out using a simplified molecular dynamics simulation technique (only hard core repulsions were assumed). As a result, it was stated that the frequency of collisions is a linear function of pressure for all fractal dimensions studied (D = 2, ..., 2.5). The frequency per unit pressure is quite complex function of the fractal dimension; however, the changes of that frequency with the fractal dimension are not strong. It was found that the frequency of collisions is controlled by the number of weakly folded sites on the surfaces and there is some mapping between the shape of adsorption energy distribution functions and this number of weakly folded sites. The results for the rough/fractal surfaces were compared with the prediction given by the Langmuir-Hertz equation (valid for smooth surface), generally the departure from the Langmuir-Hertz equation is not higher than 48% for the studied systems (i.e. for the surfaces created using the random deposition technique).

Carbon Kinetic Isotope Effects in the Oxidation of Atmospheric Alkane and Aromatic Hydrocarbons by Hydroxyl Radicals

NASA Astrophysics Data System (ADS)

Anderson, R. S.; Thompson, A. E.; Rudolph, J.; Huang, L.

2001-12-01

To interpret measurements of stable carbon isotope ratios of ambient NMHC, we need to understand the isotopic composition of the emissions, and the isotope fractionation associated with the removal of NMHC from the atmosphere. Oxidation by OH-radicals is by far the most important atmospheric process for removal of NMHC. In this presentation measurements of the kinetic isotope effects (KIEs) for the reactions of hydroxyl radicals with several C5-C8 alkanes, including cyclic, branched and straight-chain alkanes, as well as C6-C9 aromatics are presented. All KIEs are positive: compounds containing only 12C atoms react faster than 13C labelled compounds. KIEs for light n-alkanes are typically between 1.5-4‰ and are larger than mass dependent collision frequencies, deviating from the collision frequency as carbon number increases. For n-alkanes there is no statistically significant difference between the KIEs of structural isomers. KIEs for the reactions of light alkenes and aromatics with OH-radicals are considerably higher than for alkane reactions, ranging from 3-18‰ . The KIEs for the aromatic reactions can be described by a 33.3+/-2.0‰ fractionation for the addition of an OH-radical to the aromatic ring and an inverse dependency on the number of carbon atoms, added to the mass dependent collision frequency. There are indications for minor structure specific effects, however the deviations from the idealised inverse carbon number dependence is relatively small and the limited number of studied alkyl benzenes does not yet allow the identification of systematic dependencies.

On the nature of intramolecular vibrational energy transfer in dense molecular environments

NASA Astrophysics Data System (ADS)

von Benten, Rebekka S.; Abel, Bernd

2010-12-01

Transient femtosecond-IR-pump-UV-absorption probe-spectroscopy has been employed to shed light on the nature of intramolecular vibrational energy transfer (IVR) in dense molecular environments ranging from the diluted gas phase to the liquid. A general feature in our experiments and those of others is that IVR proceeds via multiple timescales if overtones or combination vibrations of high frequency modes are excited. It has been found that collisions enhance IVR if its (slower) timescales can compete with collisions. This enhancement is, however, much more weaker and rather inefficient as opposed to the effect of collisions on intermolecular energy transfer which is well known. In a series of experiments we found that IVR depends not significantly on the average energy transferred in a collision but rather on the number of collisions. The collisions are much less efficient in affecting IVR than VET. We conclude that collision induced broadening of vibrational energy levels reduces the energy gaps and enhances existing couplings between tiers. The present results are an important step forward to rationalize and understand apparently different and not consistent results from different groups on different molecular systems between gas and liquid phases.

Three species one-dimensional kinetic model for weakly ionized plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez, J., E-mail: jorge.gonzalez@upm.es; Donoso, J. M.; Tierno, S. P.

2016-06-15

A three species one-dimensional kinetic model is presented for a spatially homogeneous weakly ionized plasma subjected to the action of a time varying electric field. Planar geometry is assumed, which means that the plasma evolves in the privileged direction of the field. The energy transmitted to the electric charges is channelized to the neutrals thanks to collisions, a mechanism that influences the plasma dynamics. Charge-charge interactions have been designed as a one-dimensional collision term equivalent to the Landau operator used for fully ionized plasmas. Charge-neutral collisions are modelled by a conservative drift-diffusion operator in the Dougherty's form. The resulting setmore » of coupled integro-differential equations is solved with the stable and robust propagator integral method. This semi–analytical method feasibility accounts for non–linear effects without appealing to linearisation or simplifications, providing conservative physically meaningful solutions even for initial or emerging sharp velocity distribution function profiles. It is found that charge-neutral collisions exert a significant effect since a quite different plasma evolution arises if compared to the collisionless limit. In addition, substantial differences in the system motion are found for constant and temperature dependent collision frequencies cases.« less

Computer simulation of the Farley-Buneman instability and anomalous electron heating in the auroral ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Machida, S.; Goertz, C.K.

1988-09-01

We study the nonlinear saturation of the Farley-Buneman instability in a collisional plasma by a 2 1/2 dimensional electrostatic particle simulation which includes inelastic and elastic collisions of electrons and elastic collision of ions with neutrals. In our simulation, a uniform convection electric field is applied externally so that the relative velocity between the electrons and ions is greater than the ion sound speed and destabilizes the instability. We find a nonlinear frequency shift from higher to lower frequencies and diffusion of the wave spectrum in two dimensional wave number space. We are especially interested in finding whether the saturatedmore » wave turbulence can account for the anomalous heating rates observed in the polar ionosphere by Schlegel and St.-Maurice (1981). We find that the dominant mechanism for electron heating is due to an enhanced effective electron collision frequency and hence enhanced resistive heating as suggested by Primdahl (1986) and Robinson (1986) and not due to the heating of electrons by the electric field of the waves parallel to the magnetic field. For the ionospheric conditions discussed by Schlegel and St.-Maurice (1981) we find an anomalous heating rate of about 4 x 10/sup -7/ W/m/sup 3/. copyright American Geophysical Union 1988« less

Measurement of Biocolloid Collision Efficiencies for Granular Activated Carbon by Use of a Two-Layer Filtration Model

PubMed Central

Paramonova, Ekaterina; Zerfoss, Erica L.; Logan, Bruce E.

2006-01-01

Point-of-use filters containing granular activated carbon (GAC) are an effective method for removing certain chemicals from water, but their ability to remove bacteria and viruses has been relatively untested. Collision efficiencies (α) were determined using clean-bed filtration theory for two bacteria (Raoutella terrigena 33257 and Escherichia coli 25922), a bacteriophage (MS2), and latex microspheres for four GAC samples. These GAC samples had particle size distributions that were bimodal, but only a single particle diameter can be used in the filtration equation. Therefore, consistent with previous reports, we used a particle diameter based on the smallest diameter of the particles (derived from the projected areas of 10% of the smallest particles). The bacterial collision efficiencies calculated using the filtration model were high (0.8 ≤ α ≤ 4.9), indicating that GAC was an effective capture material. Collision efficiencies greater than unity reflect an underestimation of the collision frequency, likely as a result of particle roughness and wide GAC size distributions. The collision efficiencies for microspheres (0.7 ≤ α ≤ 3.5) were similar to those obtained for bacteria, suggesting that the microspheres were a reasonable surrogate for the bacteria. The bacteriophage collision efficiencies ranged from ≥0.2 to ≤0.4. The predicted levels of removal for 1-cm-thick carbon beds ranged from 0.8 to 3 log for the bacteria and from 0.3 to 1.0 log for the phage. These tests demonstrated that GAC can be an effective material for removal of bacteria and phage and that GAC particle size is a more important factor than relative stickiness for effective particle removal. PMID:16885264

Interference-free gas-phase thermometry at elevated pressure using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering.

PubMed

Miller, Joseph D; Dedic, Chloe E; Roy, Sukesh; Gord, James R; Meyer, Terrence R

2012-02-27

Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, low-temperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N2 and O2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, thereby improving thermometric accuracy with a time- and frequency-resolved theoretical model.

Effect of the radio frequency discharge on the dust charging process in a weakly collisional and fully ionized plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Motie, Iman; Bokaeeyan, Mahyar, E-mail: Mehyar9798@gmail.com

2015-02-15

A close analysis of dust charging process in the presence of radio frequency (RF) discharge on low pressure and fully ionized plasma for both weak and strong discharge's electric field is considered. When the electromagnetic waves pass throughout fully ionized plasma, the collision frequency of the plasma is derived. Moreover, the disturbed distribution function of plasma particles in the presence of the RF discharge is obtained. In this article, by using the Krook model, we separate the distribution function in two parts, the Maxwellian part and the perturbed part. The perturbed part of distribution can make an extra current, so-calledmore » the accretion rate of electron (or ion) current, towards a dust particle as a function of the average electron-ion collision frequency. It is proven that when the potential of dust grains increases, the accretion rate of electron current experiences an exponential reduction. Furthermore, the accretion rate of electron current for a strong electric field is relatively smaller than that for a weak electric field. The reasons are elaborated.« less

Electrostatic ion instabilities in the presence of parallel currents and transverse electric fields

NASA Technical Reports Server (NTRS)

Ganguli, G.; Palmadesso, P. J.

1988-01-01

The electrostatic ion instabilities are studied for oblique propagation in the presence of magnetic field-aligned currents and transverse localized electric fields in a weakly collisional plasma. The presence of transverse electric fields result in mode excitation for magnetic field aligned current values that are otherwise stable. The electron collisions enhance the growth while ion collisions have a damping effect. These results are discussed in the context of observations of low frequency ion modes in the auroral ionosphere by radar and rocket experiments.

Propagation of an ultrawideband electromagnetic signal in ionospheric plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soldatov, A. V., E-mail: av-soldatov@vniief.ru; Terekhin, V. A.

2016-10-15

The propagation of an ultrawideband electromagnetic signal in the ionosphere—a plasma medium with spatially nonuniform characteristics—is studied analytically in the high-frequency approximation. The effect of the plasma dielectric properties and angular divergence on the shape and frequency spectrum of the propagating signal is investigated. It is shown that the spectral energy density of the signal is preserved if collisions of ionospheric plasma electrons are neglected.

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

NASA Astrophysics Data System (ADS)

Grishkov, V. E.; Uryupin, S. A.

2017-03-01

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron-ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

Lesser prairie-chicken fence collision risk across its northern distribution

USGS Publications Warehouse

Robinson, Samantha G.; Haukos, David A.; Plumb, Reid T.; Hagen, Christian A.; Pitman, James C.; Lautenbach, Joseph M.; Sullins, Daniel S.; Kraft, John D.; Lautenbach, Jonathan D.

2016-01-01

Livestock fences have been hypothesized to significantly contribute to mortality of lesser prairie-chickens (Tympanuchus pallidicinctus); however, quantification of mortality due to fence collisions is lacking across their current distribution. Variation in fence density, landscape composition and configuration, and land use could influence collision risk of lesser prairie-chickens. We monitored fences within 3 km of known leks during spring and fall and surveyed for signs of collision occurrence within 20 m of fences in 6 study sites in Kansas and Colorado, USA during 2013 and 2014. We assessed mortality locations of radio-tagged birds (n = 286) for evidence of fence collisions and compared distance to fence relative to random points. Additionally, we quantified locations, propensity, and frequency of fences crossed by lesser prairie-chickens. We tested for landscape and vegetative characteristics that influenced fence-cross propensity and frequency of global positioning system (GPS)-marked birds. A minimum of 12,706 fence crossings occurred by GPS-marked lesser prairie-chickens. We found 3 carcasses and 12 additional possible instances of evidence of collision during >2,800 km of surveyed fences. We found evidence for a single suspected collision based on carcass evidence for 148 mortalities of transmittered birds. Mortality locations of transmittered birds were located at distances from fences 15% farther than expected at random. Our data suggested minimal biological significance and indicated that propensity and frequency of fence crossings were random processes. Lesser prairie-chickens do not appear to be experiencing significant mortality risk due to fence collisions in Kansas and Colorado. Focusing resources on other limiting factors (i.e., habitat quality) has greater potential for impact on population demography than fence marking and removal.

Effect of micellar collisions and polyvinylpyrrolidone confinement on the electrical conductivity percolation parameters of water/AOT/isooctane reverse micelles

NASA Astrophysics Data System (ADS)

Guettari, Moez; Aferni, Ahmed E. L.; Tajouri, Tahar

2017-12-01

The main aim of this paper is the analysis of micellar collisions and polymer confinement effects on the electrical conductivity percolative behavior of water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles. Firstly, we have performed conductance measurements of the system for three AOT to isooctane volume ratio, φm = 0.1 , 0.15 and 0.2 to examine the influence of micellar collisions on the percolation parameters. All the measurements were carried out over the 298.15 K-333.15 K temperature range at a fixed water to AOT molar ratio, W0 = 45 . We have assessed that the rise of micellar collisions frequency enhances the conductance percolation. Secondly, the confinement effect of a water-soluble polymer, polyvinylpyrrolidone (PVP), on the reverse micelles conductance behavior was investigated. Temperature-induced percolation, Tp , have shown a dependence on the polymer concentration, CPVP . It was also observed that for various PVP concentrations, the activation energy of percolation decreases. Finally, the values of the critical exponents determined in the presence and absence of PVP prove that the polymer affects the dynamic of percolation.

Transport and collision dynamics in periodic asymmetric obstacle arrays: Rational design of microfluidic rare-cell immunocapture devices

NASA Astrophysics Data System (ADS)

Gleghorn, Jason P.; Smith, James P.; Kirby, Brian J.

2013-09-01

Microfluidic obstacle arrays have been used in numerous applications, and their ability to sort particles or capture rare cells from complex samples has broad and impactful applications in biology and medicine. We have investigated the transport and collision dynamics of particles in periodic obstacle arrays to guide the design of convective, rather than diffusive, transport-based immunocapture microdevices. Ballistic and full computational fluid dynamics simulations are used to understand the collision modes that evolve in cylindrical obstacle arrays with various geometries. We identify previously unrecognized collision mode structures and differential size-based collision frequencies that emerge from these arrays. Previous descriptions of transverse displacements that assume unidirectional flow in these obstacle arrays cannot capture mode transitions properly as these descriptions fail to capture the dependence of the mode transitions on column spacing and the attendant change in the flow field. Using these analytical and computational simulations, we elucidate design parameters that induce high collision rates for all particles larger than a threshold size or selectively increase collision frequencies for a narrow range of particle sizes within a polydisperse population. Furthermore, we investigate how the particle Péclet number affects collision dynamics and mode transitions and demonstrate that experimental observations from various obstacle array geometries are well described by our computational model.

The Effect of a Low-Speed Automatic Brake System Estimated From Real Life Data

PubMed Central

Isaksson-Hellman, Irene; Lindman, Magdalena

2012-01-01

A substantial part of all traffic accidents involving passenger cars are rear-end collisions and most of them occur at low speed. Auto Brake is a feature that has been launched in several passenger car models during the last few years. City Safety is a technology designed to help the driver mitigate, and in certain situations avoid, rear-end collisions at low speed by automatically braking the vehicle. Studies have been presented that predict promising benefits from these kinds of systems, but few attempts have been made to show the actual effect of Auto Brake. In this study, the effect of City Safety, a standard feature on the Volvo XC60 model, is calculated based on insurance claims data from cars in real traffic crashes in Sweden. The estimated claim frequency of rear-end frontal collisions measured in claims per 1,000 insured vehicle years was 23% lower for the City Safety equipped XC60 model than for other Volvo models without the system. PMID:23169133

The effect of a low-speed automatic brake system estimated from real life data.

PubMed

Isaksson-Hellman, Irene; Lindman, Magdalena

2012-01-01

A substantial part of all traffic accidents involving passenger cars are rear-end collisions and most of them occur at low speed. Auto Brake is a feature that has been launched in several passenger car models during the last few years. City Safety is a technology designed to help the driver mitigate, and in certain situations avoid, rear-end collisions at low speed by automatically braking the vehicle.Studies have been presented that predict promising benefits from these kinds of systems, but few attempts have been made to show the actual effect of Auto Brake. In this study, the effect of City Safety, a standard feature on the Volvo XC60 model, is calculated based on insurance claims data from cars in real traffic crashes in Sweden. The estimated claim frequency of rear-end frontal collisions measured in claims per 1,000 insured vehicle years was 23% lower for the City Safety equipped XC60 model than for other Volvo models without the system.

Scattering characteristics of electromagnetic waves in time and space inhomogeneous weakly ionized dusty plasma sheath

NASA Astrophysics Data System (ADS)

Guo, Li-xin; Chen, Wei; Li, Jiang-ting; Ren, Yi; Liu, Song-hua

2018-05-01

The dielectric coefficient of a weakly ionised dusty plasma is used to establish a three-dimensional time and space inhomogeneous dusty plasma sheath. The effects of scattering on electromagnetic (EM) waves in this dusty plasma sheath are investigated using the auxiliary differential equation finite-difference time-domain method. Backward radar cross-sectional values of various parameters, including the dust particle radius, charging frequency of dust particles, dust particle concentration, effective collision frequency, rate of the electron density variation with time, angle of EM wave incidence, and plasma frequency, are analysed within the time and space inhomogeneous plasma sheath. The results show the noticeable effects of dusty plasma parameters on EM waves.

Design study of general aviation collision avoidance system

NASA Technical Reports Server (NTRS)

Bates, M. R.; Moore, L. D.; Scott, W. V.

1972-01-01

The selection and design of a time/frequency collision avoidance system for use in general aviation aircraft is discussed. The modifications to airline transport collision avoidance equipment which were made to produce the simpler general aviation system are described. The threat determination capabilities and operating principles of the general aviation system are illustrated.

Vlasov Simulation of the Effects of Collisions on the Damping of Electron Plasma Waves

NASA Astrophysics Data System (ADS)

Banks, Jeff; Berger, Richard; Chapman, Thomas; Brunner, Stephan; Tran, T.

2015-11-01

Kinetic simulation of two dimensional plasma waves through direct discretization of the Vlasov equation may be particularly attractive for situations where minimal numerical fluctuation levels are desired, such as when measuring growth rates of plasma wave instabilities. In many cases collisional effects can be important to the evolution of plasma waves because they both set a minimum damping rate for plasma waves and can scatter particles out of resonance through pitch angle scattering. Here we present Vlasov simulations of evolving electron plasma waves (EPWs) in plasmas of varying collisionality. We consider first the effects of electron-ion pitch angle collisions on the frequency and damping, Landau and collisional, of small-amplitude EPWs for a range of collision rates. In addition, the wave phase velocities are extracted from the simulation results and compared with theory. For this study we use the Eulerian-based kinetic code LOKI that evolves the Vlasov-Poisson system in 2+2-dimensional phase space. We then discuss extensions of the collision operator to include thermalization. Discretization of these collision operators using 4th order accurate conservative finite-differencing will be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the LDRD program at LLNL under project tracking code 15-ERD-038.

Electron-Impact Excitation and Ionization in Air

DTIC Science & Technology

2009-09-01

average collision frequency, is more than 100 times larger. Even in the slightly ionized regime with only 1% electrons, the frequency of electron...information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and...physics-based model of nonequilibrium chemistry and radiation in hypersonic flow, it is timely to investigate and update the electron collision cross

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Young-Dae

The plasmon and screening effects on the entanglement fidelity for the elastic electron-ion collision are investigated in hot quantum plasmas. The partial wave analysis and effective interaction including the plasmon couplings are employed to obtain the entanglement fidelity function in hot quantum plasmas. It is shown that the plasmon effect enhances the entanglement fidelity in quantum plasmas for 0<{beta}({identical_to}({Dirac_h}/2{pi}){omega}{sub p}/k{sub B}T)<0.8 and, however, suppresses the entanglement fidelity for 0.8<{beta}<1, where {omega}{sub p} is the plasmon frequency, k{sub B} is the Boltzmann constant, and T is the plasma temperature. It is also found that the entanglement fidelity decreases with increasing Debyemore » length and collision energy.« less

Predicting deer-vehicle collisions in an urban area.

PubMed

Found, Rob; Boyce, Mark S

2011-10-01

Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Damping of Bernstein-Greene-Kruskal modes in collisional plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valentini, Francesco

2008-02-15

In this paper, the effect of Coulomb collisions on the stability of Bernstein-Greene-Kruskal (BGK) modes [I. B. Bernstein, J. M. Greene, and M. D. Krukal, Phys. Rev. 108, 546 (1957)] is analyzed by comparing the numerical results of collisional particle-in-cell (PIC) simulations with the theoretical predictions by Zakharov and Karpman [V. E. Zakharov and V. I. Karpman, Sov. Phys. JETP 16, 351 (1963)], for the collisional damping of nonlinear plasma waves. In the absence of collisions, BGK modes are undamped nonlinear electrostatic oscillations, solutions of the Vlasov-Poisson equations; in these structures nonlinearity manifests as the formation of a plateau inmore » the resonant region of the particle distribution function, due to trapping of resonant particles, thus preventing linear Landau damping. When particle-particle Coulomb collisions are effective, this plateau is smoothed out since collisions drive the velocity distribution towards the Maxwellian shape, thus destroying the BGK structure. As shown by Zakharov and Karpman in 1963, under certain assumptions, an exponential time decay with constant damping rate is predicted for the electric field amplitude and a linear dependence of the damping rate on the collision frequency is found. In this paper, the theory by Zakharov and Karpman is revisited and the effects of collisions on the stability of BGK modes and on the long time evolution of nonlinear Landau damping are numerically investigated. The numerical results are obtained through a collisional PIC code that reproduces a physical phenomenology also observed in recent experiments with trapped pure electron plasmas.« less

Comparison of DNA decatenation by Escherichia coli topoisomerase IV and topoisomerase III: implications for non-equilibrium topology simplification

PubMed Central

Seol, Yeonee; Hardin, Ashley H.; Strub, Marie-Paule; Charvin, Gilles; Neuman, Keir C.

2013-01-01

Type II topoisomerases are essential enzymes that regulate DNA topology through a strand-passage mechanism. Some type II topoisomerases relax supercoils, unknot and decatenate DNA to below thermodynamic equilibrium. Several models of this non-equilibrium topology simplification phenomenon have been proposed. The kinetic proofreading (KPR) model postulates that strand passage requires a DNA-bound topoisomerase to collide twice in rapid succession with a second DNA segment, implying a quadratic relationship between DNA collision frequency and relaxation rate. To test this model, we used a single-molecule assay to measure the unlinking rate as a function of DNA collision frequency for Escherichia coli topoisomerase IV (topo IV) that displays efficient non-equilibrium topology simplification activity, and for E. coli topoisomerase III (topo III), a type IA topoisomerase that unlinks and unknots DNA to equilibrium levels. Contrary to the predictions of the KPR model, topo IV and topo III unlinking rates were linearly related to the DNA collision frequency. Furthermore, topo III exhibited decatenation activity comparable with that of topo IV, supporting proposed roles for topo III in DNA segregation. This study enables us to rule out the KPR model for non-equilibrium topology simplification. More generally, we establish an experimental approach to systematically control DNA collision frequency. PMID:23460205

Exploring the effects of roadway characteristics on the frequency and severity of head-on crashes: case studies from Malaysian federal roads.

PubMed

Hosseinpour, Mehdi; Yahaya, Ahmad Shukri; Sadullah, Ahmad Farhan

2014-01-01

Head-on crashes are among the most severe collision types and of great concern to road safety authorities. Therefore, it justifies more efforts to reduce both the frequency and severity of this collision type. To this end, it is necessary to first identify factors associating with the crash occurrence. This can be done by developing crash prediction models that relate crash outcomes to a set of contributing factors. This study intends to identify the factors affecting both the frequency and severity of head-on crashes that occurred on 448 segments of five federal roads in Malaysia. Data on road characteristics and crash history were collected on the study segments during a 4-year period between 2007 and 2010. The frequency of head-on crashes were fitted by developing and comparing seven count-data models including Poisson, standard negative binomial (NB), random-effect negative binomial, hurdle Poisson, hurdle negative binomial, zero-inflated Poisson, and zero-inflated negative binomial models. To model crash severity, a random-effect generalized ordered probit model (REGOPM) was used given a head-on crash had occurred. With respect to the crash frequency, the random-effect negative binomial (RENB) model was found to outperform the other models according to goodness of fit measures. Based on the results of the model, the variables horizontal curvature, terrain type, heavy-vehicle traffic, and access points were found to be positively related to the frequency of head-on crashes, while posted speed limit and shoulder width decreased the crash frequency. With regard to the crash severity, the results of REGOPM showed that horizontal curvature, paved shoulder width, terrain type, and side friction were associated with more severe crashes, whereas land use, access points, and presence of median reduced the probability of severe crashes. Based on the results of this study, some potential countermeasures were proposed to minimize the risk of head-on crashes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of electromagnetic wave scattering from an inhomogeneous plasma layer using Green's function volume integral equation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soltanmoradi, Elmira; Shokri, Babak, E-mail: b-shokri@sbu.ac.ir; Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19839-63113

Gigahertz electromagnetic wave scattering from an inhomogeneous collisional plasma layer with bell-like and Epstein electron density distributions is studied by the Green's function volume integral equation method to find the reflectance, transmittance, and absorbance coefficients of this inhomogeneous plasma. Also, the effects of the frequency of the electromagnetic wave, plasma parameters, such as collision frequency, electron density, and plasma thickness, and the effects of the profile of the electron density on the electromagnetic wave scattering from this plasma slab are investigated. According to the results, when the electron density, collision frequency, and plasma thickness are increased, collisional absorbance is enhanced,more » and as a result, the absorbance bandwidth of plasma is broadened. Moreover, this broadening is more evident for plasma with bell-like electron density profile. Also, the bandwidth of the frequency and the range of pressure in which plasma behaves as a good reflector are determined in this article. According to the results, the bandwidth of the frequency is decreased for thicker plasma with bell-like profile, while it does not vary for a different plasma thickness with Epstein profile. Moreover, the range of the pressure is decreased for bell-like profile in comparison with Epstein profile. Furthermore, due to the sharp inhomogeneity of the Epstein profile, the coefficients of plasma that are uniform for plasma with bell-like profile are changed for plasma with Epstein profile, and some perturbations are seen.« less

Brake reactions of distracted drivers to pedestrian Forward Collision Warning systems.

PubMed

Lubbe, Nils

2017-06-01

Forward Collision Warning (FCW) can be effective in directing driver attention towards a conflict and thereby aid in preventing or mitigating collisions. FCW systems aiming at pedestrian protection have been introduced onto the market, yet an assessment of their safety benefits depends on the accurate modeling of driver reactions when the system is activated. This study contributes by quantifying brake reaction time and brake behavior (deceleration levels and jerk) to compare the effectiveness of an audio-visual warning only, an added haptic brake pulse warning, and an added Head-Up Display in reducing the frequency of collisions with pedestrians. Further, this study provides a detailed data set suited for the design of assessment methods for car-to-pedestrian FCW systems. Brake response characteristics were measured for heavily distracted drivers who were subjected to a single FCW event in a high-fidelity driving simulator. The drivers maintained a self-regulated speed of 30km/h in an urban area, with gaze direction diverted from the forward roadway by a secondary task. Collision rates and brake reaction times differed significantly across FCW settings. Brake pulse warnings resulted in the lowest number of collisions and the shortest brake reaction times (mean 0.8s, SD 0.29s). Brake jerk and deceleration were independent of warning type. Ninety percent of drivers exceeded a maximum deceleration of 3.6m/s 2 and a jerk of 5.3m/s 3 . Brake pulse warning was the most effective FCW interface for preventing collisions. In addition, this study presents the data required for driver modeling for car-to-pedestrian FCW similar to Euro NCAP's 2015 car-to-car FCW assessment. Practical applications: Vehicle manufacturers should consider the introduction of brake pulse warnings to their FCW systems. Euro NCAP could introduce an assessment that quantifies the safety benefits of pedestrian FCW systems and thereby aid the proliferation of effective systems. Copyright © 2017 National Safety Council and Elsevier Ltd. All rights reserved.

Electrostatic wave modulation in collisional pair-ion plasmas

NASA Astrophysics Data System (ADS)

Sikdar, Arnab; Adak, Ashish; Ghosh, Samiran; Khan, Manoranjan

2018-05-01

The effects of ion-neutral collision on the electrostatic wave packets in the absence of the magnetic field in a pair-ion plasma have been investigated. Considering a two-fluid plasma model with the help of the standard perturbation technique, two distinct electrostatic modes have been observed, namely, a low-frequency ion acoustic mode and a high-frequency ion plasma mode. The dynamics of the modulated wave is governed by a damped nonlinear Schrödinger equation. Damping of the soliton occurs due to the ion-neutral collision. The analytical and numerical investigation reveals that the ion acoustic mode is both stable and unstable, which propagates in the form of dark solitons and bright solitons, respectively, whereas the ion plasma mode is unstable, propagating in the form of a bright soliton. Results are discussed in the context of the fullerene pair-ion plasma experiments.

A Propagator Expansion Method for Solving Linearized Plasma Kinetic Equations with Collisions.

DTIC Science & Technology

1984-06-25

of the collision frequency. For the linearized Balescu -Lenard collision * operator and for the zero-order distribution function Maxwellian, we obtain...Rev. 94:511. 3. Lenard, A. , and Bernstein, 1. 13. (1958) Phys. Rev. 112:1456. 4. Dougherty, J. P. (1964) Phys. Fluids 7:1788. 5. Balescu , R. (1960...long wavelength limit for the linearized Balescu - Lenard collision operator and for f0 Maxwellian. We obLain the total L damping rate 1 jry which is

Transport in sheared stochastic magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanden Eijnden, E.; Balescu, R.

1997-02-01

The transport of test particles in a stochastic magnetic field with a sheared component is studied. Two stages in the particle dynamics are distinguished depending on whether the collisional effects perpendicular to the main field are negligible or not. Whenever the perpendicular collisions are unimportant, the particles show a subdiffusive behavior which is slower in the presence of shear. The particle dynamics is then inhomogeneous and non-Markovian and no diffusion coefficient may be properly defined. When the perpendicular collision frequency is small, this subdiffusive stage may be very long. In the truly asymptotic stage, however, the perpendicular collisions must bemore » accounted for and the particle motion eventually becomes diffusive. Here again, however, the shear is shown to reduce the anomalous diffusion coefficient of the system. {copyright} {ital 1997 American Institute of Physics.}« less

Wireless SAW passive tag temperature measurement in the collision case

NASA Astrophysics Data System (ADS)

Sorokin, A.; Shepeta, A.; Wattimena, M.

2018-04-01

This paper describes temperature measurement in the multisensor systems based on the radio-frequency identification SAW passive tags which are currently applied in the electric power systems and the switchgears. Different approaches of temperature measurement in the collision case are shown here. The study is based on the tag model with specific topology, which allows us to determine temperature through the response signal with time-frequency information. This research considers the collision case for several passive tags as the temperature sensors which are placed in the switchgear. This research proposal is to analyze the possibility of using several SAW passive sensors in the collision case. We consider the using of the different typical elements for passive surface acoustic wave tag which applies as an anticollision passive sensor. These wireless sensors based on the surface acoustic waves tags contain specifically coded structures. This topology makes possible the reliability of increasing tag identification and the temperature measurement in the collision case. As the results for this case we illustrate simultaneous measurement of at least six sensors.

Electron-ion collision-frequency for x-ray Thomson scattering in dense plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faussurier, Gérald, E-mail: gerald.faussurier@cea.fr; Blancard, Christophe

2016-01-15

Two methods are presented to calculate the electron-ion collision-frequency in dense plasmas using an average-atom model. The first one is based on the Kubo-Greenwood approach. The second one uses the Born and Lenard-Balescu approximations. The two methods are used to calculate x-ray Thomson scattering spectra. Illustrations are shown for dense beryllium and aluminum plasmas. Comparisons with experiment are presented in the case of an x-ray Thomson scattering spectrum.

Wave modeling in a cylindrical non-uniform helicon discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, L.; Hole, M. J.; Caneses, J. F.

2012-08-15

A radio frequency field solver based on Maxwell's equations and a cold plasma dielectric tensor is employed to describe wave phenomena observed in a cylindrical non-uniform helicon discharge. The experiment is carried out on a recently built linear plasma-material interaction machine: The magnetized plasma interaction experiment [Blackwell et al., Plasma Sources Sci. Technol. (submitted)], in which both plasma density and static magnetic field are functions of axial position. The field strength increases by a factor of 15 from source to target plate, and the plasma density and electron temperature are radially non-uniform. With an enhancement factor of 9.5 to themore » electron-ion Coulomb collision frequency, a 12% reduction in the antenna radius, and the same other conditions as employed in the experiment, the solver produces axial and radial profiles of wave amplitude and phase that are consistent with measurements. A numerical study on the effects of axial gradient in plasma density and static magnetic field on wave propagations is performed, revealing that the helicon wave has weaker attenuation away from the antenna in a focused field compared to a uniform field. This may be consistent with observations of increased ionization efficiency and plasma production in a non-uniform field. We find that the relationship between plasma density, static magnetic field strength, and axial wavelength agrees well with a simple theory developed previously. A numerical scan of the enhancement factor to the electron-ion Coulomb collision frequency from 1 to 15 shows that the wave amplitude is lowered and the power deposited into the core plasma decreases as the enhancement factor increases, possibly due to the stronger edge heating for higher collision frequencies.« less

Anti-collision radio-frequency identification system using passive SAW tags

NASA Astrophysics Data System (ADS)

Sorokin, A. V.; Shepeta, A. P.

2017-06-01

Modern multi sensor systems should have high operating speed and resistance to climate impacts. Radiofrequency systems use passive SAW tags for identification items and vehicles. These tags find application in industry, traffic remote control systems, and railway remote traffic control systems for identification and speed measuring. However, collision of the passive SAW RFID tags hinders development passive RFID SAW technology in Industry. The collision problem for passive SAW tags leads for incorrect identification and encoding each tag. In our researching, we suggest approach for identification of several passive SAW tags in collision case.

Vibrational and Electronic Energy Transfer and Dissociation of Diatomic Molecules by Electron Collisions

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Langhoff, Stephen R. (Technical Monitor)

1995-01-01

At high altitudes and velocities equal to or greater than the geosynchronous return velocity (10 kilometers per second), the shock layer of a hypersonic flight will be in thermochemical nonequilibrium and partially ionized. The amount of ionization is determined by the velocity. For a trans atmospheric flight of 10 kilometers per second and at an altitude of 80 kilometers, a maximum of 1% ionization is expected. At a velocity of 12 - 17 kilometer per second, such as a Mars return mission, up to 30% of the atoms and molecules in the flow field will be ionized. Under those circumstances, electrons play an important role in determining the internal states of atoms and molecules in the flow field and hence the amount of radiative heat load and the distance it takes for the flow field to re-establish equilibrium. Electron collisions provide an effective means of transferring energy even when the electron number density is as low as 1%. Because the mass of an electron is 12,760 times smaller than the reduced mass of N2, its average speed, and hence its average collision frequency, is more than 100 times larger. Even in the slightly ionized regime with only 1% electrons, the frequency of electron-molecule collisions is equal to or larger than that of molecule-molecule collisions, an important consideration in the low density part of the atmosphere. Three electron-molecule collision processes relevant to hypersonic flows will be considered: (1) vibrational excitation/de-excitation of a diatomic molecule by electron impact, (2) electronic excitation/de-excitation, and (3) dissociative recombination in electron-diatomic ion collisions. A review of available data, both theory and experiment, will be given. Particular attention will be paid to tailoring the molecular physics to the condition of hypersonic flows. For example, the high rotational temperatures in a hypersonic flow field means that most experimental data carried out under room temperatures are not applicable. Also, the average electron temperature is expected to be between 10,000 and 20,000 K. Thus only data for low energy electrons are relevant to the model.

Using collisions and resonances to tilting Uranus

NASA Astrophysics Data System (ADS)

Rogoszinski, Zeeve; Hamilton, Douglas

2018-01-01

Uranus’ large obliquity (98°) is widely thought to have occurred from a polar strike with an Earth sized object. Morbidelli et al. (2012) argue that two or more collisions are required in order to explain the prograde motion of Uranus’ satellites. These impactors could have been less massive by about a factor of ten, but multiple polar strikes are still improbable as even larger mass impactors would be needed for more equatorial collisions. Here we explore an alternative non-collisional model inspired by the explanation to Saturn’s significant tilt (27°). Ward and Hamilton (2004) & Hamilton and Ward (2004) argue that a secular resonance currently between Saturn’s spin axis and Neptune’s orbital pole is responsible for Saturn’s large obliquity. Unfortunately, Uranus’ axial precession frequency today is too long to match any of the current planets’ fundamental frequencies. Boué and Laskar (2010) explain that Uranus may have harbored an improbably large moon in the past which could have sped up the planet’s axial precession frequency enough to resonate with the regression of its own orbital pole. We explore another scenario which requires only the interactions between the giant planets.Thommes et al. (1999, 2002, 2003) argue that at least the cores of Uranus and Neptune were formed in between Jupiter and Saturn, as the density of the protoplanetary disk was greater there. If Neptune was scattered outward before Uranus, then a secular spin-orbit resonance between the two planets is possible. However, driving Uranus’ obliquity to near 90° with a resonance capture requires a timescale on the order of 100 Myr. If Neptune migrated out quicker or its orbital inclination was initially larger, then we find that the resulting resonance kick can tilt Uranus more than 40° in a reasonable timespan. This could replace one of the impactors required in the collisional scenario described by Morbidelli et al. (2012), but in most situations the effect of such a kick is only about 10°. Since collisions are therefore necessary to explain at least part of the tilting, we are now considering hybrid models that involve combinations of resonance captures and kicks, and collisions.

An electrostatic charge measurement of blowing snow particles focusing on collision frequency to the snow surface

NASA Astrophysics Data System (ADS)

Omiya, S.; Sato, A.

2010-12-01

Blowing snow particles are known to have an electrostatic charge. This charge may be a contributing factor in the formation of snow drifts and snow cornices and changing of the trajectory of blowing snow particles. These formations and phenomena can cause natural disaster such as an avalanche and a visibility deterioration, and obstruct transportation during winter season. Therefore, charging phenomenon of the blowing snow particles is an important issue in terms of not only precise understanding of the particle motion but disaster prevention. The primary factor of charge accumulation to the blowing snow particles is thought to be due to “saltation” of them. The “saltation” is one of movement forms of blowing snow: when the snow particles are transported by the wind, they repeat frictional collisions with the snow surface. In previous studies, charge-to-mass ratios measured in the field were approximately -50 to -10 μC/kg, and in the wind tunnel were approximately -0.8 to -0.1 μC/kg. While there were qualitatively consistent in sign, negative, there were huge gaps quantitatively between them. One reason of those gaps is speculated to be due to differences in fetch. In other words, the difference of the collision frequency of snow particles to the snow surface has caused the gaps. But it is merely a suggestion and that has not been confirmed. The purpose of this experiment is to measure the charge of blowing snow particles focusing on the collision frequency and clarify the relationship between them. Experiments were carried out in the cryogenic wind tunnel of Snow and Ice Research Center (NIED, JAPAN). A Faraday cage and an electrometer were used to measure the charge of snow particles. These experiments were conducted over the hard snow surface condition to prevent the erosion of the snow surface and the generation of new snow particles from the surface. The collision frequency of particle was controlled by changing the wind velocity (4.5 to 7 m/s) under the fixed fetch (12m). The number of collisions of particle was converted from the wind velocity using an equation obtained by Kosugi et al. (2004). Blowing snow particles tend to accumulate negative charges gradually with increase of the number of collisions to the snow surface. As a result, it is demonstrated that the gaps between the field values and the wind tunnel ones were due to difference of the collision frequency of snow particles. Assuming a logarithmic relationship as first approximation between the measured charges and the number of collisions, the charge-to-mass ratios will reach roughly the same value which was obtained in the field with several hundreds collisions. For instance, fetch is needed roughly 200m for blowing snow particles to gain -30 μC/kg under the following conditions: air temperature -20 degrees Celsius, wind velocity 7m/s and hard snow surface. REFERENCE: Kosugi et al., (2004): Dependence of drifting snow saltation length on snow surface hardness. Cold Reg. Sci. Technol., 39, 133-139.

Measurements and modeling of radio frequency field structures in a helicon plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, C. A.; Chen, Guangye; Arefiev, A. V.

2011-01-01

Measurements of the radio frequency (rf) field structure, plasma density, and electron temperature are presented for a 1 kW argon helicon plasma source. The measured profiles change considerably when the equilibrium magnetic field is reversed. The measured rf fields are identified as fields of radially localized helicon waves, which propagate in the axial direction. The rf field structure is compared to the results of two-dimensional cold plasma full-wave simulations for the measured density profiles. Electron collision frequency is adjusted in the simulations to match the simulated and measured field profiles. The resulting frequency is anomalously high, which is attributed tomore » the excitation of an ion-acoustic instability. The calculated power deposition is insensitive to the collision frequency and accounts for most of the power supplied by the rf-generator.« less

Self-similar space-time evolution of an initial density discontinuity

NASA Astrophysics Data System (ADS)

Rekaa, V. L.; Pécseli, H. L.; Trulsen, J. K.

2013-07-01

The space-time evolution of an initial step-like plasma density variation is studied. We give particular attention to formulate the problem in a way that opens for the possibility of realizing the conditions experimentally. After a short transient time interval of the order of the electron plasma period, the solution is self-similar as illustrated by a video where the space-time evolution is reduced to be a function of the ratio x/t. Solutions of this form are usually found for problems without characteristic length and time scales, in our case the quasi-neutral limit. By introducing ion collisions with neutrals into the numerical analysis, we introduce a length scale, the collisional mean free path. We study the breakdown of the self-similarity of the solution as the mean free path is made shorter than the system length. Analytical results are presented for charge exchange collisions, demonstrating a short time collisionless evolution with an ensuing long time diffusive relaxation of the initial perturbation. For large times, we find a diffusion equation as the limiting analytical form for a charge-exchange collisional plasma, with a diffusion coefficient defined as the square of the ion sound speed divided by the (constant) ion collision frequency. The ion-neutral collision frequency acts as a parameter that allows a collisionless result to be obtained in one limit, while the solution of a diffusion equation is recovered in the opposite limit of large collision frequencies.

An evaluation of a mitigation strategy for deer-vehicle collisions

USGS Publications Warehouse

Bissonette, John A.; Rosa, Silvia

2012-01-01

High mule deer Odocoileus hemionus mortality in southwestern Utah led to the establishment of a mitigation strategy with two major objectives: 1) reduction of wildlife-vehicle collisions and 2) restoration of landscape connectivity to facilitate wildlife movement across the roaded landscape. During our study, we assessed the effectiveness of the mitigation measures in reducing mule deer mortality in the following ways: 1) we compared the number of deer-vehicle collisions in the newly fenced area with a control area without fencing; 2) we analyzed the ‘end-of-the-fence’ problem, defined here as increased mortality of mule deer at the ends of the 2.4-m high exclusion fences; and 3) we evaluated the frequency of animal crossings of the new underpasses using remotely-sensed cameras and compared them with crossing frequency rates for a 20-year-old control underpass. We compared six years of pre-construction mortality (during 1998-2003) with two years of post-construction data on mortality (during 2005-2006) and found a 98.5% decline in deer mortalities in the treatment (i.e. fenced, jump-outs and underpasses) vs a 2.9% decline in the control (i.e. no fences, no jump-outs and no underpasses). We detected no end-of-the-fence problems related to deer mortality. Migratory movements during fall and spring were clearly reflected in the use of underpass. Overall results demonstrated that the mitigation strategy was effective and reduced the number of deer-vehicle accidents, while allowing wildlife movement across the landscape.

Theory of plasma contactors in ground-based experiments and low Earth orbit

NASA Technical Reports Server (NTRS)

Gerver, M. J.; Hastings, Daniel E.; Oberhardt, M. R.

1990-01-01

Previous theoretical work on plasma contactors as current collectors has fallen into two categories: collisionless double layer theory (describing space charge limited contactor clouds) and collisional quasineutral theory. Ground based experiments at low current are well explained by double layer theory, but this theory does not scale well to power generation by electrodynamic tethers in space, since very high anode potentials are needed to draw a substantial ambient electron current across the magnetic field in the absence of collisions (or effective collisions due to turbulence). Isotropic quasineutral models of contactor clouds, extending over a region where the effective collision frequency upsilon sub e exceeds the electron cyclotron frequency omega sub ce, have low anode potentials, but would collect very little ambient electron current, much less than the emitted ion current. A new model is presented, for an anisotropic contactor cloud oriented along the magnetic field, with upsilon sub e less than omega sub ce. The electron motion along the magnetic field is nearly collisionless, forming double layers in that direction, while across the magnetic field the electrons diffuse collisionally and the potential profile is determined by quasineutrality. Using a simplified expression for upsilon sub e due to ion acoustic turbulence, an analytic solution has been found for this model, which should be applicable to current collection in space. The anode potential is low and the collected ambient electron current can be several times the emitted ion current.

Design and evaluation of safety operation VR training system for robotic catheter surgery.

PubMed

Wang, Yu; Guo, Shuxiang; Li, Yaxin; Tamiya, Takashi; Song, Yu

2018-01-01

A number of remote robotic catheter systems have been developed to protect physicians from X-ray exposure in endovascular surgery. However, the teleoperation prevents the physicians sensing the force directly which may easily result in healthy vessels injured. To realize the safe operation, a tissue protection-based VR training system has been developed in this paper to prevent collateral damage by collision. The integrated VR simulator cannot only remind the novice possible collisions by visual signs, but also cooperate with the newly designed tissue protection mechanism to remit collision trauma beforehand. Such mechanism exploits the diameter variable pulley in order to implement the safe interaction between catheter and vasculature. To testify the effectiveness of the tissue protection in training system, we invited four non-medical students to participate the successive 5 days training session. The evaluation results show that the average impingement distance (representing tissue damage) to vascular wall has been reduced to 0.6 mm, and the collision frequency is greatly decreased which implies the realization of relative safe catheterization.

Parametric Excitation of Electrostatic Dust-Modes by Ion-Cyclotron Waves in a Dusty Plasma

NASA Astrophysics Data System (ADS)

Islam, M. K.; Salahuddin, M.; Ferdous, T.; Salimullah, M.

A large amplitude electrostatic ion-cyclotron wave propagating through a magnetized and collisional dusty plasma undergoes strong parametric instability off the low-frequency dust-modes. The presence of the dust-component has effect on the nonlinear coupling via the dust-modes. The ion-neutral collisions are seen to have significant effect on the damping and consequent overall growth of the parametric excitation process.

Nonlinear electromagnetic propagation in ionosphere: Inclusion of electron temperature dependence of the collision parameter (δ)

NASA Astrophysics Data System (ADS)

Sodha, Mahendra Singh; Verma, R. K.

2018-02-01

In this paper, the authors have taken into account the electron temperature dependence of δ, the fraction of excess energy of an electron over that of a neutral particle which is exchanged in an elastic collision. The dependence of electron temperature, electron collision frequency, and refractive index/absorption coefficient, corresponding to different frequencies, on the intensity of the wave (specifically square of the amplitude of electric vector) at heights of 90 km, 100 km, and 110 km in the ionosphere, has been evaluated. The results have been discussed and graphically illustrated. The derived dependence of n and k on Eo 2 has been used to study the nonlinear horizontal propagation of electromagnetic waves at the heights of 90 km, 100 km, and 110 km in the ionosphere.

Influence of damping on proton energy loss in plasmas of all degeneracies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barriga-Carrasco, Manuel D.

2007-07-15

The purpose of the present paper is to describe the effects of electron-electron collisions on the stopping power of plasmas of any degeneracy. Plasma targets are considered fully ionized so electronic stopping is only due to the free electrons. We focus our analysis on plasmas which electronic density is around solid values n{sub e}{approx_equal}10{sup 23} cm{sup -3} and which temperature is around T{approx_equal}10 eV; these plasmas are in the limit of weakly coupled plasmas. This type of plasma has not been studied extensively though it is very important for inertial confinement fusion. The electronic stopping is obtained from an exactmore » quantum mechanical evaluation, which takes into account the degeneracy of the target plasma, and later it is compared with common classical and degenerate approximations. Differences are around 30% in some cases which can produce bigger mistakes in further energy deposition and projectile range studies. Then we consider electron-electron collisions in the exact quantum mechanical electronic stopping calculation. Now the maximum stopping occurs at velocities smaller than for the calculations without considering collisions for all kinds of plasmas analyzed. The energy loss enhances for velocities smaller than the velocity at maximum while decreases for higher velocities. Latter effects are magnified with increasing collision frequency. Differences with the same results for the case of not taking into account collisions are around 20% in the analyzed cases.« less

The impact of pedestrian countdown signals on pedestrian-motor vehicle collisions: a reanalysis of data from a quasi-experimental study.

PubMed

Richmond, Sarah A; Willan, Andrew R; Rothman, Linda; Camden, Andi; Buliung, Ron; Macarthur, Colin; Howard, Andrew

2014-06-01

To perform a more sophisticated analysis of previously published data that advances the understanding of the efficacy of pedestrian countdown signal (PCS) installation on pedestrian-motor vehicle collisions (PMVCs), in the city of Toronto, Canada. This is an updated analysis of the same dataset from Camden et al. A quasi-experimental design was used to evaluate the effect of PCS on PMVC. A Poisson regression analysis, using a one-group comparison of PMVC, pre-PCS installation to post-PCS installation was used, controlling for season and temporal effects. The outcome was the frequency of reported PMVC (January 2000-December 2009). Similar models were used to analyse specific types of collisions defined by age of pedestrian, injury severity, and pedestrian and vehicle action. Incidence rate ratios with 95% CI are presented. This analysis included 9262 PMVC, 2760 during or after PCS installation, at 1965 intersections. There was a 26% increase in the rate of collisions, pre to post-PCS installation (incidence rate ratio=1.26, 95% CI 1.11 to 1.42). The installation of PCS at 1965 signalised intersections in the city of Toronto resulted in an increase in PMVC rates post-PCS installation. PCSs may have an unintended consequence of increasing pedestrian-motor vehicle collisions in some settings. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Numerical study of low-frequency discharge oscillations in a 5 kW Hall thruster

NASA Astrophysics Data System (ADS)

Le, YANG; Tianping, ZHANG; Juanjuan, CHEN; Yanhui, JIA

2018-07-01

A two-dimensional particle-in-cell plasma model is built in the R–Z plane to investigate the low-frequency plasma oscillations in the discharge channel of a 5 kW LHT-140 Hall thruster. In addition to the elastic, excitation, and ionization collisions between neutral atoms and electrons, the Coulomb collisions between electrons and electrons and between electrons and ions are analyzed. The sheath characteristic distortion is also corrected. Simulation results indicate the capability of the built model to reproduce the low-frequency oscillation with high accuracy. The oscillations of the discharge current and ion density produced by the model are consistent with the existing conclusions. The model predicts a frequency that is consistent with that calculated by the zero-dimensional theoretical model.

A computational study of systemic hydration in vocal fold collision.

PubMed

Bhattacharya, Pinaki; Siegmund, Thomas

2014-01-01

Mechanical stresses develop within vocal fold (VF) soft tissues due to phonation-associated vibration and collision. These stresses in turn affect the hydration of VF tissue and thus influence voice health. In this paper, high-fidelity numerical computations are described, taking into account fully 3D geometry, realistic tissue and air properties, and high-amplitude vibration and collision. A segregated solver approach is employed, using sophisticated commercial solvers for both the VF tissue and glottal airflow domains. The tissue viscoelastic properties were derived from a biphasic formulation. Two cases were considered, whereby the tissue viscoelastic properties corresponded to two different volume fractions of the fluid phase of the VF tissue. For each case, hydrostatic stresses occurring as a result of vibration and collision were investigated. Assuming the VF tissue to be poroelastic, interstitial fluid movement within VF tissue was estimated from the hydrostatic stress gradient. Computed measures of overall VF dynamics (peak airflow velocity, magnitude of VF deformation, frequency of vibration and contact pressure) were well within the range of experimentally observed values. The VF motion leading to mechanical stresses within the VFs and their effect on the interstitial fluid flux is detailed. It is found that average deformation and vibration of VFs tend to increase the state of hydration of the VF tissue, whereas VF collision works to reduce hydration.

Constraining the sensitivity of iodide adduct chemical ionization mass spectrometry to multifunctional organic molecules using the collision limit and thermodynamic stability of iodide ion adducts

DOE PAGES

Lopez-Hilfiker, Felipe D.; Iyer, Siddarth; Mohr, Claudia; ...

2016-04-06

The sensitivity of a chemical ionization mass spectrometer (ions formed per number density of analytes) is fundamentally limited by the collision frequency between reagent ions and analytes, known as the collision limit, the ion–molecule reaction time, and the transmission efficiency of product ions to the detector. We use the response of a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) to N 2O 5, known to react with iodide at the collision limit, to constrain the combined effects of ion–molecule reaction time, which is strongly influenced by mixing and ion losses in the ion–molecule reaction drift tube. A mass spectrometric voltage scanningmore » procedure elucidates the relative binding energies of the ion adducts, which influence the transmission efficiency of molecular ions through the electric fields within the vacuum chamber. Together, this information provides a critical constraint on the sensitivity of a ToF-CIMS towards a wide suite of routinely detected multifunctional organic molecules for which no calibration standards exist. Lastly, we describe the scanning procedure and collision limit determination, and we show results from the application of these constraints to the measurement of organic aerosol composition at two different field locations.« less

The slow collisional E×B ion drift characterized as the major instability mechanism of a poorly magnetized plasma column with an inward-directed radial electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierre, Thiéry

2016-04-15

The low-frequency instability of a cylindrical poorly magnetized plasma with an inward-directed radial electric field is studied changing the gas pressure and the ion cyclotron frequency. The unstable frequency always decreases when the gas pressure is increased indicating collisional effects. At a fixed pressure, the unstable frequency increases with the magnetic field when the B-field is low and decreases at larger magnetic field strength. We find that the transition between these two regimes is obtained when the ion cyclotron frequency equals the ion-neutrals collision frequency. This is in agreement with the theory of the slow-ion drift instability induced by themore » collisional slowing of the electric ion drift [A. Simon, Phys. Fluids 6, 382 (1963)].« less

Asteroid collisions, craters, regoliths, and lifetimes

NASA Technical Reports Server (NTRS)

Chapman, C. R.

1978-01-01

Laboratory experiments and computer modeling are used to predict the development of regoliths on all asteroids more than a few tens of kilometers in diameter, allowing for a wide range in the intrinsic strength of asteroidal surface materials. The high frequency of interasteroid collisions requires nearly all asteroids to be fragments of precursors.

Both size-frequency distribution and sub-populations of the main-belt asteroid population are consistent with YORP-induced rotational fission

NASA Astrophysics Data System (ADS)

Jacobson, S.; Scheeres, D.; Rossi, A.; Marzari, F.; Davis, D.

2014-07-01

From the results of a comprehensive asteroid-population-evolution model, we conclude that the YORP-induced rotational-fission hypothesis has strong repercussions for the small size end of the main-belt asteroid size-frequency distribution and is consistent with observed asteroid-population statistics and with the observed sub-populations of binary asteroids, asteroid pairs and contact binaries. The foundation of this model is the asteroid-rotation model of Marzari et al. (2011) and Rossi et al. (2009), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur; Scheeres 2007) and binary-asteroid evolution (Jacobson & Scheeres, 2011). The YORP-effect timescale for large asteroids with diameters D > ˜ 6 km is longer than the collision timescale in the main belt, thus the frequency of large asteroids is determined by a collisional equilibrium (e.g. Bottke 2005), but for small asteroids with diameters D < ˜ 6 km, the asteroid-population evolution model confirms that YORP-induced rotational fission destroys small asteroids more frequently than collisions. Therefore, the frequency of these small asteroids is determined by an equilibrium between the creation of new asteroids out of the impact debris of larger asteroids and the destruction of these asteroids by YORP-induced rotational fission. By introducing a new source of destruction that varies strongly with size, YORP-induced rotational fission alters the slope of the size-frequency distribution. Using the outputs of the asteroid-population evolution model and a 1-D collision evolution model, we can generate this new size-frequency distribution and it matches the change in slope observed by the SKADS survey (Gladman 2009). This agreement is achieved with both an accretional power-law or a truncated ''Asteroids were Born Big'' size-frequency distribution (Weidenschilling 2010, Morbidelli 2009). The binary-asteroid evolution model is highly constrained by the modeling done in Jacobson & Scheeres, and therefore the asteroid-population evolution model has only two significant free parameters: the ratio of low-to-high-mass-ratio binaries formed after rotational fission events and the mean strength of the binary YORP (BYORP) effect. Using this model, we successfully reproduce the observed small-asteroid sub-populations, which orthogonally constrain the two free parameters. We find the outcome of rotational fission most likely produces an initial mass-ratio fraction that is four to eight times as likely to produce high-mass-ratio systems as low-mass-ratio systems, which is consistent with rotational fission creating binary systems in a flat distribution with respect to mass ratio. We also find that the mean of the log-normal BYORP coefficient distribution B ≈ 10^{-2}.

InChIKey collision resistance: an experimental testing

PubMed Central

2012-01-01

InChIKey is a 27-character compacted (hashed) version of InChI which is intended for Internet and database searching/indexing and is based on an SHA-256 hash of the InChI character string. The first block of InChIKey encodes molecular skeleton while the second block represents various kinds of isomerism (stereo, tautomeric, etc.). InChIKey is designed to be a nearly unique substitute for the parent InChI. However, a single InChIKey may occasionally map to two or more InChI strings (collision). The appearance of collision itself does not compromise the signature as collision-free hashing is impossible; the only viable approach is to set and keep a reasonable level of collision resistance which is sufficient for typical applications. We tested, in computational experiments, how well the real-life InChIKey collision resistance corresponds to the theoretical estimates expected by design. For this purpose, we analyzed the statistical characteristics of InChIKey for datasets of variable size in comparison to the theoretical statistical frequencies. For the relatively short second block, an exhaustive direct testing was performed. We computed and compared to theory the numbers of collisions for the stereoisomers of Spongistatin I (using the whole set of 67,108,864 isomers and its subsets). For the longer first block, we generated, using custom-made software, InChIKeys for more than 3 × 1010 chemical structures. The statistical behavior of this block was tested by comparison of experimental and theoretical frequencies for the various four-letter sequences which may appear in the first block body. From the results of our computational experiments we conclude that the observed characteristics of InChIKey collision resistance are in good agreement with theoretical expectations. PMID:23256896

InChIKey collision resistance: an experimental testing.

PubMed

Pletnev, Igor; Erin, Andrey; McNaught, Alan; Blinov, Kirill; Tchekhovskoi, Dmitrii; Heller, Steve

2012-12-20

InChIKey is a 27-character compacted (hashed) version of InChI which is intended for Internet and database searching/indexing and is based on an SHA-256 hash of the InChI character string. The first block of InChIKey encodes molecular skeleton while the second block represents various kinds of isomerism (stereo, tautomeric, etc.). InChIKey is designed to be a nearly unique substitute for the parent InChI. However, a single InChIKey may occasionally map to two or more InChI strings (collision). The appearance of collision itself does not compromise the signature as collision-free hashing is impossible; the only viable approach is to set and keep a reasonable level of collision resistance which is sufficient for typical applications.We tested, in computational experiments, how well the real-life InChIKey collision resistance corresponds to the theoretical estimates expected by design. For this purpose, we analyzed the statistical characteristics of InChIKey for datasets of variable size in comparison to the theoretical statistical frequencies. For the relatively short second block, an exhaustive direct testing was performed. We computed and compared to theory the numbers of collisions for the stereoisomers of Spongistatin I (using the whole set of 67,108,864 isomers and its subsets). For the longer first block, we generated, using custom-made software, InChIKeys for more than 3 × 1010 chemical structures. The statistical behavior of this block was tested by comparison of experimental and theoretical frequencies for the various four-letter sequences which may appear in the first block body.From the results of our computational experiments we conclude that the observed characteristics of InChIKey collision resistance are in good agreement with theoretical expectations.

Enhancement of ohmic and stochastic heating by resonance effects in capacitive radio frequency discharges: a theoretical approach.

PubMed

Mussenbrock, T; Brinkmann, R P; Lieberman, M A; Lichtenberg, A J; Kawamura, E

2008-08-22

In low-pressure capacitive radio frequency discharges, two mechanisms of electron heating are dominant: (i) Ohmic heating due to collisions of electrons with neutrals of the background gas and (ii) stochastic heating due to momentum transfer from the oscillating boundary sheath. In this work we show by means of a nonlinear global model that the self-excitation of the plasma series resonance which arises in asymmetric capacitive discharges due to nonlinear interaction of plasma bulk and sheath significantly affects both Ohmic heating and stochastic heating. We observe that the series resonance effect increases the dissipation by factors of 2-5. We conclude that the nonlinear plasma dynamics should be taken into account in order to describe quantitatively correct electron heating in asymmetric capacitive radio frequency discharges.

Simulation of deterministic energy-balance particle agglomeration in turbulent liquid-solid flows

NASA Astrophysics Data System (ADS)

Njobuenwu, Derrick O.; Fairweather, Michael

2017-08-01

An efficient technique to simulate turbulent particle-laden flow at high mass loadings within the four-way coupled simulation regime is presented. The technique implements large-eddy simulation, discrete particle simulation, a deterministic treatment of inter-particle collisions, and an energy-balanced particle agglomeration model. The algorithm to detect inter-particle collisions is such that the computational costs scale linearly with the number of particles present in the computational domain. On detection of a collision, particle agglomeration is tested based on the pre-collision kinetic energy, restitution coefficient, and van der Waals' interactions. The performance of the technique developed is tested by performing parametric studies on the influence of the restitution coefficient (en = 0.2, 0.4, 0.6, and 0.8), particle size (dp = 60, 120, 200, and 316 μm), Reynolds number (Reτ = 150, 300, and 590), and particle concentration (αp = 5.0 × 10-4, 1.0 × 10-3, and 5.0 × 10-3) on particle-particle interaction events (collision and agglomeration). The results demonstrate that the collision frequency shows a linear dependency on the restitution coefficient, while the agglomeration rate shows an inverse dependence. Collisions among smaller particles are more frequent and efficient in forming agglomerates than those of coarser particles. The particle-particle interaction events show a strong dependency on the shear Reynolds number Reτ, while increasing the particle concentration effectively enhances particle collision and agglomeration whilst having only a minor influence on the agglomeration rate. Overall, the sensitivity of the particle-particle interaction events to the selected simulation parameters is found to influence the population and distribution of the primary particles and agglomerates formed.

Combining electromagnetic gyro-kinetic particle-in-cell simulations with collisions

NASA Astrophysics Data System (ADS)

Slaby, Christoph; Kleiber, Ralf; Könies, Axel

2017-09-01

It has been an open question whether for electromagnetic gyro-kinetic particle-in-cell (PIC) simulations pitch-angle collisions and the recently introduced pullback transformation scheme (Mishchenko et al., 2014; Kleiber et al., 2016) are consistent. This question is positively answered by comparing the PIC code EUTERPE with an approach based on an expansion of the perturbed distribution function in eigenfunctions of the pitch-angle collision operator (Legendre polynomials) to solve the electromagnetic drift-kinetic equation with collisions in slab geometry. It is shown how both approaches yield the same results for the frequency and damping rate of a kinetic Alfvén wave and how the perturbed distribution function is substantially changed by the presence of pitch-angle collisions.

Division III Collision Sports Are Not Associated with Neurobehavioral Quality of Life.

PubMed

Meehan, William P; Taylor, Alex M; Berkner, Paul; Sandstrom, Noah J; Peluso, Mark W; Kurtz, Matthew M; Pascual-Leone, Alvaro; Mannix, Rebekah

2016-01-15

We sought to determine whether the exposure to the sub-concussive blows that occur during division III collegiate collision sports affect later life neurobehavioral quality-of-life measures. We conducted a cross-sectional study of alumni from four division III colleges, targeting those between the ages of 40-70 years, using several well-validated quality-of-life measures for executive function, general concerns, anxiety, depression, emotional and behavior dyscontrol, fatigue, positive affect, sleep disturbance, and negative consequences of alcohol use. We used multivariable linear regression to assess for associations between collision sport participation and quality-of-life measures while adjusting for covariates including age, gender, race, annual income, highest educational degree, college grades, exercise frequency, and common medical conditions. We obtained data from 3702 alumni, more than half of whom (2132) had participated in collegiate sports, 23% in collision sports, 23% in non-contact sports. Respondents with a history of concussion had worse self-reported health on several measures. When subjects with a history of concussion were removed from the analyses in order to assess for any potential effect of sub-concussive blows alone, negative consequences of alcohol use remained higher among collision sport athletes (β-coefficient 1.957, 95% CI 0.827-3.086). There were, however, no other significant associations between exposure to collision sports during college and any other quality-of-life measures. Our results suggest that, in the absence of a history of concussions, participation in collision sports at the Division III collegiate level is not a risk factor for worse long-term neurobehavioral outcomes, despite exposure to repeated sub-concussive blows.

A Photographic Study of Freezing of Water Droplets Falling Freely in Air

NASA Technical Reports Server (NTRS)

Dorsch, Robert G.; Levine, Joseph

1952-01-01

A photographic technique for investigating water droplets of diameter less than 200 microns falling freely in air at temperatures between 0 C and -50 C has been devised and used to determine: (i) The shape of frozen droplets (2) The occurrence of collisions of partly frozen or of frozen and liquid droplets (3) The statistics on the freezing temperatures of individual free-falling droplets A considerable number of droplets were found to have a nonspherical shape after freezing because of various protuberances and frost growth, and droplet aggregates formed by collision. The observed frequency of collision of partly frozen droplets showed good order of magnitude agreement with the frequency computed from theoretical collection efficiencies. The freezing temperature statistics indicated a general similarity of the data to those obtained for droplets frozen on a metallic surface in previous experiments.

Alcohol Effects on Simulated Driving in Frequent and Infrequent Binge Drinkers

PubMed Central

Bernosky-Smith, Kimberly A.; Shannon, Erin E.; Roth, Alicia J.; Liguori, Anthony

2011-01-01

Objective Compared to non-bingers, binge drinkers are more likely to drive while intoxicated. The extent to which binge frequency impacts confidence in driving and subsequent driving impairment is unknown. This study compared the effects of an experimenter-delivered alcohol binge on subjective impairment and simulated driving ability in female High and Low Frequency bingers. Methods Female drinkers were assigned to High Frequency (n=30) or Low Frequency (n=30) binge groups based on their Alcohol Use Questionnaire responses. At 30-minute intervals within a two-hour period, participants received either a placebo drink (n=15 per group) or a 0.2 g/kg dose of alcohol (n=15 per group; cumulative dose 0.8 g/kg). Self-reported impairment, driving confidence, and simulated driving were then measured. Results Self-reported confidence in driving was significantly lower after alcohol than after placebo in Low Frequency but not High Frequency bingers. Self-reported impairment and collisions during simulated driving were significantly greater after alcohol than after placebo in both Low Frequency and High Frequency bingers. Conclusions The impairing effects of a single alcohol binge on driving ability in females are not influenced by binge frequency. However, high binge frequency may be associated with a less cautious approach to post-binge driving. PMID:21542027

Ion acoustic turbulence in a 100-A LaB6 hollow cathode

NASA Astrophysics Data System (ADS)

Jorns, Benjamin A.; Mikellides, Ioannis G.; Goebel, Dan M.

2014-12-01

The temporal fluctuations in the near plume of a 100-A LaB6 hollow cathode are experimentally investigated. A probe array is employed to measure the amplitude and dispersion of axial modes in the plume, and these properties are examined parametrically as a function of cathode operating conditions. The onset of ion acoustic turbulence is observed at high current and is characterized by a power spectrum that exhibits a cutoff at low frequency and an inverse dependence on frequency at high values. The amplitude of the turbulence is found to decrease with flow rate but to depend nonmonotonically on discharge current. Estimates of the anomalous collision frequency based on experimental measurements indicate that the ion acoustic turbulence collision frequency can exceed the classical rate at high discharge current densities by nearly two orders of magnitude.

Study of a contracted glow in low-frequency plasma-jet discharges operating with argon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minotti, F.; Giuliani, L.; Xaubet, M.

2015-11-15

In this work, we present an experimental and theoretical study of a low frequency, atmospheric plasma-jet discharge in argon. The discharge has the characteristics of a contracted glow with a current channel of submillimeter diameter and a relatively high voltage cathode layer. In order to interpret the measurements, we consider the separate modeling of each region of the discharge: main channel and cathode layer, which must then be properly matched together. The main current channel was modeled, extending a previous work, as similar to an arc in which joule heating is balanced by lateral heat conduction, without thermal equilibrium betweenmore » electrons and heavy species. The cathode layer model, on the other hand, includes the emission of secondary electrons by ion impact and by additional mechanisms, of which we considered emission due to collision of atoms excited at metastable levels, and field-enhanced thermionic emission (Schottky effect). The comparison of model and experiment indicates that the discharge can be effectively sustained in its contracted form by the secondary electrons emitted by collision of excited argon atoms, whereas thermionic emission is by far insufficient to provide the necessary electrons.« less

Digital-Difference Processing For Collision Avoidance.

NASA Technical Reports Server (NTRS)

Shores, Paul; Lichtenberg, Chris; Kobayashi, Herbert S.; Cunningham, Allen R.

1988-01-01

Digital system for automotive crash avoidance measures and displays difference in frequency between two sinusoidal input signals of slightly different frequencies. Designed for use with Doppler radars. Characterized as digital mixer coupled to frequency counter measuring difference frequency in mixer output. Technique determines target path mathematically. Used for tracking cars, missiles, bullets, baseballs, and other fast-moving objects.

Nonlinear optical conductivity and subharmonic instabilities of graphene in a strong electromagnetic field

NASA Astrophysics Data System (ADS)

Sun, Zhiyuan; Basov, Dimitri; Fogler, Michael

We study theoretically the second-order nonlinear optical conductivity σ (2) of graphene as a function of frequency and momentum. We distinguish two regimes. At frequencies ω higher than the temperature-dependent electron-electron collision rate γee- 1 , the conductivity σ (2) can be derived from the semiclassical kinetic equation. The calculation requires taking into account the photon drag (Lorentz force) due to the ac magnetic field. In the low-frequency hydrodynamic regime ω <<γee- 1 , the nonlinear conductivity has a different form and the photon drag effect is suppressed. As a consequence of the nonlinearity, a strong enough photoexcitation can cause spontaneous generation of collective modes in a graphene strip: plasmons in the high-frequency regime and energy waves (demons) in the hydrodynamic one. The dominant instability occurs at frequency ω / 2 .

Hydrodynamic-to-ballistic crossover in Dirac materials

NASA Astrophysics Data System (ADS)

Svintsov, D.

2018-03-01

We develop an analytically solvable classical kinetic model of spatially dispersive transport in Dirac materials accounting for strong electron-electron (e-e) and electron-hole (e-h) collisions. We use this model to track the evolution of graphene conductivity and properties of its collective excitations across the hydrodynamic-to-ballistic crossover. We find the relaxation rate of electric current by e-e collisions that is possible due to the lack of Galilean invariance and introduce a universal numerical measure of this noninvariance. We find the two branches of collective excitations in the Dirac fluid: plasmons and electron-hole sound. The sound waves persist at frequencies exceeding the e-e collision frequency, have a small viscous damping at the neutrality point, but acquire large damping due to e-h friction even at slight doping. On the contrary, plasmons acquire strong frictional damping at the neutrality point and become well defined in doped samples.

On the stability of the internal kink mode in the banana regime

NASA Astrophysics Data System (ADS)

Fogaccia, G.; Romanelli, F.

1995-01-01

The stability of the internal kink mode is investigated taking into account the kinetic response associated to the trapped thermal ions. Ion-ion collisions and diamagnetic effects in the layer are also considered. A significant stabilizing contribution is obtained, even at low-β values, on the mode, which might be stable, on present experiments, even though predicted unstable according to the Bussac criterion [Bussac et al., Phys. Rev. Lett. 35, 1638 (1975)]. In addition, a trapped-ion instability is found, characterized by mode frequency of the order of the trapped-ion bounce-averaged magnetic drift frequency.

A Computational Study of Systemic Hydration in Vocal Fold Collision

PubMed Central

Bhattacharya, Pinaki; Siegmund, Thomas

2013-01-01

Mechanical stresses develop within vocal fold (VF) soft tissues, due to phonation-associated vibration and collision. These stresses in turn affect the hydration of VF tissue and thus influence voice health. In this paper, high-fidelty numerical computations are described taking into account fully three-dimensional geometry, realistic tissue and air properties, and high-amplitude vibration and collision. A segregated solver approach is employed, using sophisticated commercial solvers for both the VF tissue and glottal airflow domains. The tissue viscoelastic properties were derived from a biphasic formulation. Two cases were considered, whereby the tissue viscoelastic properties corresponded to two different volume fractions of the fluid phase of the VF tissue. For each case, hydrostatic stresses occurring as a result of vibration and collision were investigated. Assuming the VF tissue to be poroelastic, interstitial fluid movement within VF tissue was estimated from the hydrostatic stress gradient. Computed measures of overall VF dynamics (peak air-flow velocity, magnitude of VF deformation, frequency of vibration and contact pressure) were well within the range of experimentally observed values. The VF motion leading to mechanical stresses within the VFs and their effect on the interstitial fluid flux is detailed. It is found that average deformation and vibration of VFs tends to increase the state of hydration of the VF tissue whereas VF collision works to reduce hydration. PMID:23531170

Advances in 133Cs Fountains: Control of the Cold Collision Shift and Observation of Feshbach Resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bize, S.; Marion, H.; Cacciapuoti, L.

2005-05-05

This paper describes the work performed at BNM-SYRTE (Observatoire de Paris) over the past few years toward the improvement and the use of microwave frequency standards using laser-cooled atoms. First, recent improvements of the 133Cs and 87Rb atomic fountains are described. An important advance is the achievement of a fractional frequency instability of 1.6 x 10-14{tau}-1/2 where {tau} is the measurement time in seconds, thanks to the routine use of a cryogenic sapphire oscillator as an ultra-stable local frequency reference. The second advance is a powerful method to control the frequency shift due to cold collisions. These two advances leadmore » to a frequency stability of 2 x 10-16 at 50,000 s for the first time for primary standards. In addition, these clocks realize the SI second with an accuracy of 7 x 10-16, one order of magnitude below that of uncooled devices.« less

Magnetic Field Effects and Electromagnetic Wave Propagation in Highly Collisional Plasmas.

NASA Astrophysics Data System (ADS)

Bozeman, Steven Paul

The homogeneity and size of radio frequency (RF) and microwave driven plasmas are often limited by insufficient penetration of the electromagnetic radiation. To investigate increasing the skin depth of the radiation, we consider the propagation of electromagnetic waves in a weakly ionized plasma immersed in a steady magnetic field where the dominant collision processes are electron-neutral and ion-neutral collisions. Retaining both the electron and ion dynamics, we have adapted the theory for cold collisionless plasmas to include the effects of these collisions and obtained the dispersion relation at arbitrary frequency omega for plane waves propagating at arbitrary angles with respect to the magnetic field. We discuss in particular the cases of magnetic field enhanced wave penetration for parallel and perpendicular propagation, examining the experimental parameters which lead to electromagnetic wave propagation beyond the collisional skin depth. Our theory predicts that the most favorable scaling of skin depth with magnetic field occurs for waves propagating nearly parallel to B and for omega << Omega_{rm e} where Omega_{rm e} is the electron cyclotron frequency. The scaling is less favorable for propagation perpendicular to B, but the skin depth does increase for this case as well. Still, to achieve optimal wave penetration, we find that one must design the plasma configuration and antenna geometry so that one generates primarily the appropriate angles of propagation. We have measured plasma wave amplitudes and phases using an RF magnetic probe and densities using Stark line broadening. These measurements were performed in inductively coupled plasmas (ICP's) driven with a standard helical coil, a reverse turn (Stix) coil, and a flat spiral coil. Density measurements were also made in a microwave generated plasma. The RF magnetic probe measurements of wave propagation in a conventional ICP with wave propagation approximately perpendicular to B show an increase in skin depth with magnetic field and a damping of the effect of B with pressure. The flat coil geometry which launches waves more nearly parallel to B allows enhanced wave penetration at higher pressures than the standard helical coil.

Division III Collision Sports Are Not Associated with Neurobehavioral Quality of Life

PubMed Central

Taylor, Alex M.; Berkner, Paul; Sandstrom, Noah J.; Peluso, Mark W.; Kurtz, Matthew M.; Pascual-Leone, Alvaro; Mannix, Rebekah

2016-01-01

Abstract We sought to determine whether the exposure to the sub-concussive blows that occur during division III collegiate collision sports affect later life neurobehavioral quality-of-life measures. We conducted a cross-sectional study of alumni from four division III colleges, targeting those between the ages of 40–70 years, using several well-validated quality-of-life measures for executive function, general concerns, anxiety, depression, emotional and behavior dyscontrol, fatigue, positive affect, sleep disturbance, and negative consequences of alcohol use. We used multivariable linear regression to assess for associations between collision sport participation and quality-of-life measures while adjusting for covariates including age, gender, race, annual income, highest educational degree, college grades, exercise frequency, and common medical conditions. We obtained data from 3702 alumni, more than half of whom (2132) had participated in collegiate sports, 23% in collision sports, 23% in non-contact sports. Respondents with a history of concussion had worse self-reported health on several measures. When subjects with a history of concussion were removed from the analyses in order to assess for any potential effect of sub-concussive blows alone, negative consequences of alcohol use remained higher among collision sport athletes (β-coefficient 1.957, 95% CI 0.827-3.086). There were, however, no other significant associations between exposure to collision sports during college and any other quality-of-life measures. Our results suggest that, in the absence of a history of concussions, participation in collision sports at the Division III collegiate level is not a risk factor for worse long-term neurobehavioral outcomes, despite exposure to repeated sub-concussive blows. PMID:26193380

Local shear instabilities in weakly ionized, weakly magnetized disks

NASA Technical Reports Server (NTRS)

Blaes, Omer M.; Balbus, Steven A.

1994-01-01

We extend the analysis of axisymmetric magnetic shear instabilities from ideal magnetohydrodynamic (MHD) flows to weakly ionized plasmas with coupling between ions and neutrals caused by collisions, ionization, and recombination. As part of the analysis, we derive the single-fluid MHD dispersion relation without invoking the Boussinesq approximation. This work expands the range of applications of these instabilities from fully ionized accretion disks to molecular disks in galaxies and, with somewhat more uncertainty, to protostellar disks. Instability generally requires the angular velocity to decrease outward, the magnetic field strengths to be subthermal, and the ions and neutrals to be sufficiently well coupled. If ionization and recombination processes can be neglected on an orbital timescale, adequate coupling is achieved when the collision frequency of a given neutral with the ions exceeds the local epicyclic freqency. When ionization equilibrium is maintained on an orbital timescale, a new feature is present in the disk dynamics: in contrast to a single-fluid system, subthermal azimuthal fields can affect the axisymmetric stability of weakly ionized two-fluid systems. We discuss the underlying causes for this behavior. Azimuthal fields tend to be stabilizing under these circumstances, and good coupling between the neutrals and ions requires the collision frequency to exceed the epicyclic frequency by a potentially large secant factor related to the magnetic field geometry. When the instability is present, subthermal azimuthal fields may also reduce the growth rate unless the collision frequency is high, but this is important only if the field strengths are very subthermal and/or the azimuthal field is the dominant field component. We briefly discuss our results in the context of the Galactic center circumnuclear disk, and suggest that the shear instability might be present there, and be responsible for the observed turbulent motions.

Manipulating ion-atom collisions with coherent electromagnetic radiation.

PubMed

Kirchner, Tom

2002-08-26

Laser-assisted ion-atom collisions are considered in terms of a nonperturbative quantum mechanical description of the electronic motion. It is shown for the system He(2+) - H at 2 keV/amu that the collision dynamics depend strongly on the initial phase of the laser field and the applied wavelength. Whereas electronic transitions are caused by the concurrent action of the field and the projectile ion at relatively low frequencies, they can be separated into modified collisional capture and field ionization events in the region above the one-photon ionization threshold.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laskin, Julia

In this work, resonant ejection coupled with surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer is used to examine fragmentation kinetics of two singly protonated hexapeptides, RYGGFL and KYGGFL, containing the basic arginine residue and less basic lysine residue at the N-terminus. The kinetics of individual reaction channels at different collision energies are probed by applying a short ejection pulse (1 ms) in resonance with the cyclotron frequency of a selected fragment ion and varying the delay time between ion-surface collision and resonant ejection while keeping total reaction delay time constant. Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of themore » experimental data provides accurate threshold energies and activation entropies of individual reaction channels. Substitution of arginine with less basic lysine has a pronounced effect on the observed fragmentation kinetics of several pathways, including the b2 ion formation, but has little or no effect on formation of the b5+H2O fragment ion. The combination of resonant ejection SID, time- and collision energy-resolved SID, and RRKM modeling of both types of experimental data provides a detailed mechanistic understanding of the primary dissociation pathways of complex gaseous ions.« less

Effects of magnetic field on the interaction between terahertz wave and non-uniform plasma slab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Yuan; Han, YiPing; Guo, LiXin

2015-10-15

In this paper, the interaction between terahertz electromagnetic wave and a non-uniform magnetized plasma slab is investigated. Different from most of the published literatures, the plasma employed in this work is inhomogeneous in both collision frequency and electron density. Profiles are introduced to describe the non-uniformity of the plasma slab. At the same time, magnetic field is applied to the background of the plasma slab. It came out with an interesting phenomenon that there would be a valley in the absorption band as the plasma's electromagnetic characteristic is affected by the magnetic field. In addition, the valley located just nearmore » the middle of the absorption peak. The cause of the valley's appearance is inferred in this paper. And the influences of the variables, such as magnetic field strength, electron density, and collision frequency, are discussed in detail. The objective of this work is also pointed out, such as the applications in flight communication, stealth, emissivity, plasma diagnose, and other areas of plasma.« less

The link between texting and motor vehicle collision frequency in the orthopaedic trauma population

PubMed Central

Issar, Neil M.; Kadakia, Rishin J.; Tsahakis, James M.; Yoneda, Zachary T.; Sethi, Manish K.; Mir, Hassan R.; Archer, Kristin; Obremskey, William T.; Jahangir, Amir A.

2013-01-01

Abstract: Background: This study will evaluate whether or not texting frequency while driving and/or texting frequency in general are associated with an increased risk of incurring a motor vehicle collision (MVC) resulting in orthopaedic trauma injuries. Methods: All patients who presented to the Vanderbilt University Medical Center Orthopaedic Trauma Clinic were administered a questionnaire to determine background information, mean phone use, texting frequency, texting frequency while driving, and whether or not the injury was the result of an MVC in which the patient was driving. Results: 237 questionnaires were collected. 60 were excluded due to incomplete date, leaving 57 questionnaires in the MVC group and 120 from patients with non-MVC injuries. Patients who sent more than 30 texts per week (“heavy texters”) were 2.22 times more likely to be involved in an MVC than those who texted less frequently. 84% of respondents claimed to never text while driving. Dividing the sample into subsets on the basis of age (25 years of age or below considered “young adult,” and above 25 years of age considered “adult”),young, heavy texters were 6.76 times more likely to be involved in an MVC than adult non-heavy texters (p = 0.000). Similarly, young adult, non-heavy texters were 6.65 (p = 0.005) times more likely to be involved in an MVC, and adult, heavy texters were 1.72 (p = 0.186) times more likely to be involved in an MVC. Conclusions: Patients injured in an MVC sent more text messages per week than non-MVC patients. Additionally, controlling for age demonstrated that young age and heavy general texting frequency combined had the highest increase in MVC risk, with the former being the variable of greatest effect. PMID:23416747

The link between texting and motor vehicle collision frequency in the orthopaedic trauma population.

PubMed

Issar, Neil M; Kadakia, Rishin J; Tsahakis, James M; Yoneda, Zachary T; Sethi, Manish K; Mir, Hassan R; Archer, Kristin; Obremskey, William T; Jahangir, Amir A

2013-07-01

This study will evaluate whether or not texting frequency while driving and/or texting frequency in general are associated with an increased risk of incurring a motor vehicle collision (MVC) resulting in orthopaedic trauma injuries. All patients who presented to the Vanderbilt University Medical Center Orthopaedic Trauma Clinic were administered a questionnaire to determine background information, mean phone use, texting frequency, texting frequency while driving, and whether or not the injury was the result of an MVC in which the patient was driving. 237 questionnaires were collected. 60 were excluded due to incomplete date, leaving 57 questionnaires in the MVC group and 120 from patients with non-MVC injuries. Patients who sent more than 30 texts per week ("heavy texters") were 2.22 times more likely to be involved in an MVC than those who texted less frequently. 84% of respondents claimed to never text while driving. Dividing the sample into subsets on the basis of age (25 years of age or below considered "young adult," and above 25 years of age considered "adult"),young, heavy texters were 6.76 times more likely to be involved in an MVC than adult non-heavy texters (p = 0.000). Similarly, young adult, non-heavy texters were 6.65 (p = 0.005) times more likely to be involved in an MVC, and adult, heavy texters were 1.72 (p = 0.186) times more likely to be involved in an MVC. Patients injured in an MVC sent more text messages per week than non-MVC patients. Additionally, controlling for age demonstrated that young age and heavy general texting frequency combined had the highest increase in MVC risk, with the former being the variable of greatest effect.

Gyrokinetics with Advanced Collision Operators

NASA Astrophysics Data System (ADS)

Belli, E. A.; Candy, J.

2014-10-01

For gyrokinetic studies in the pedestal region, collisions are expected to play a more critical role than in the core and there is concern that more advanced collision operators, as well as numerical methods optimized for the strong collisionality regime, are needed. For this purpose, a new gyrokinetic solver CGYRO has been developed for precise studies of high collisionality regimes. Building on GYRO and NEO, CGYRO uses the NEO pitch angle and energy velocity-space coordinate system to optimize the accuracy of the collision dynamics, particularly for multi-species collisions and including energy diffusion. With implementation of the reduced Hirshman-Sigmar collision operator with full cross-species coupling, CGYRO recovers linear ITG growth rates and the collisional GAM test at moderate collision frequency. Methods to improve the behavior in the collisionless regime, particularly for the trapped/passing particle boundary physics for kinetic electrons, are studied. Extensions to advanced model operators with finite-k⊥ corrections, e.g., the Sugama operator, and the impact of high collisionality on linear gyrokinetic stability in the edge are explored. Work supported by the US DOE under DE-FG02-95ER54309.

Numerical analysis of deposition frequency for successive droplets coalescence dynamics

NASA Astrophysics Data System (ADS)

Cheng, Xiaoding; Zhu, Yunlong; Zhang, Lei; Zhang, Dingyi; Ku, Tao

2018-04-01

A pseudopotential based multi-relaxation-time lattice Boltzmann model is employed to investigate the dynamic behaviors of successive droplets' impact and coalescence on a solid surface. The effects of deposition frequency on the morphology of the formed line are investigated with a zero receding contact angle by analyzing the droplet-to-droplet coalescence dynamics. Two collision modes (in-phase mode and out-of-phase mode) between the pre-deposited bead and the subsequent droplet are identified depending on the deposition frequency. A uniform line can be obtained at the optimal droplet spacing in the in-phase mode (Δt* < 1.875). However, a scalloped line pattern is formed in the out-of-phase mode (Δt* > 1.875). It is found that decreasing the droplet spacing or advancing contact angle can improve the smoothness of line in the out-of-phase mode. Furthermore, the effects of deposition frequency on the morphology of the formed lines are validated to be applicable to cases with a finite receding contact angle.

Edge-to-center plasma density ratios in two-dimensional plasma discharges

NASA Astrophysics Data System (ADS)

Lucken, R.; Croes, V.; Lafleur, T.; Raimbault, J.-L.; Bourdon, A.; Chabert, P.

2018-03-01

Edge-to-center plasma density ratios—so-called h factors—are important parameters for global models of plasma discharges as they are used to calculate the plasma losses at the reactor walls. There are well-established theories for h factors in the one-dimensional (1D) case. The purpose of this paper is to establish h factors in two-dimensional (2D) systems, with guidance from a 2D particle-in-cell (PIC) simulation. We derive analytical solutions of a 2D fluid theory that includes the effect of ion inertia, but assumes a constant (independent of space) ion collision frequency (using an average ion velocity) across the discharge. Predicted h factors from this 2D fluid theory have the same order of magnitude and the same trends as the PIC simulations when the average ion velocity used in the collision frequency is set equal to the ion thermal velocity. The best agreement is obtained when the average ion velocity varies with pressure (but remains independent of space), going from half the Bohm velocity at low pressure, to the thermal velocity at high pressure. The analysis also shows that a simple correction of the widely-used 1D heuristic formula may be proposed to accurately incorporate 2D effects.

Collisions between ultracold metastable He atoms

NASA Astrophysics Data System (ADS)

Woestenenk, G.; Mastwijk, H. C.; Thomsen, J. W.; vna der Straten, P.; Pieksma, M.; van Rijnbach, M.; Niehaus, A.

1999-06-01

We present experimental data on collisions between excited He-atoms occurring in a magneto-optical trap (MOT) at a temperature of 1.1 mK. He(2 3S)-atoms produced in a discharge are pre-cooled and trapped using the He(2 3S)-He(2 3P 2) transition for laser manipulation. Measurements of the Penning ionization rate as a function of the MOT-laser frequency are presented and theoretically analyzed. The analysis, based on a model which is presented in detail for the first time, leads to a good understanding of the complex nature of optical collisions. Further, first and preliminary measurements of the kinetic energy distributions of He 2+- and He +-ions formed by Penning ionization in optical collisions are presented.

Determination of plasma density from data on the ion current to cylindrical and planar probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voloshin, D. G., E-mail: dvoloshin@mics.msu.su; Vasil’eva, A. N.; Kovalev, A. S.

2016-12-15

To improve probe methods of plasma diagnostics, special probe measurements were performed and numerical models describing ion transport to a probe with allowance for collisions were developed. The current–voltage characteristics of cylindrical and planar probes were measured in an RF capacitive discharge in argon at a frequency of 81 MHz and plasma densities of 10{sup 10}–10{sup 11} cm{sup –3}, typical of modern RF reactors. 1D and 2D numerical models based on the particle-in-cell method with Monte Carlo collisions for simulating ion motion and the Boltzmann equilibrium for electrons are developed to describe current collection by a probe. The models weremore » used to find the plasma density from the ion part of the current–voltage characteristic, study the effect of ion collisions, and verify simplified approaches to determining the plasma density. A 1D hydrodynamic model of the ion current to a cylindrical probe with allowance for ion collisions is proposed. For a planar probe, a method to determine the plasma density from the averaged numerical results is developed. A comparative analysis of different approaches to calculating the plasma density from the ion current to a probe is performed.« less

Vibration parameters affecting vibration-induced reflex muscle activity.

PubMed

Cidem, Muharrem; Karacan, Ilhan; Cakar, Halil Ibrahim; Cidem, Mehmet; Sebik, Oguz; Yilmaz, Gizem; Turker, Kemal Sitki; Karamehmetoglu, Safak Sahir

2017-03-01

To determine vibration parameters affecting the amplitude of the reflex activity of soleus muscle during low-amplitude whole-body vibration (WBV). This study was conducted on 19 participants. Vibration frequencies of 25, 30, 35, 40, 45, and 50 Hz were used. Surface electromyography, collision force between vibration platform and participant's heel measured using a force sensor, and acceleration measured using an accelerometer fixed to the vibration platform were simultaneously recorded. The collision force was the main independent predictor of electromyographic amplitude. The essential parameter of vibration affecting the amplitude of the reflex muscle activity is the collision force.

Kinetic theory of Jeans instability of a dusty plasma.

PubMed

Pandey, B P; Lakhina, G S; Krishan, V

1999-12-01

A kinetic theory of the Jeans instability of a dusty plasma has been developed in the present work. The effect of grain charge fluctuations due to the attachment of electrons and ions to the grain surface has been considered in the framework of Krook's collisional model. We demonstrate that the grain charge fluctuations alter the growth rate of the gravitational collapse of the dusty plasma. The Jeans length has been derived under limiting cases, and its dependence on the attachment frequency is shown. In the absence of gravity, we see that the damping rate of the dust acoustic mode is proportional to the electron-dust collision frequency.

Adaptive time-stepping Monte Carlo integration of Coulomb collisions

NASA Astrophysics Data System (ADS)

Särkimäki, K.; Hirvijoki, E.; Terävä, J.

2018-01-01

We report an accessible and robust tool for evaluating the effects of Coulomb collisions on a test particle in a plasma that obeys Maxwell-Jüttner statistics. The implementation is based on the Beliaev-Budker collision integral which allows both the test particle and the background plasma to be relativistic. The integration method supports adaptive time stepping, which is shown to greatly improve the computational efficiency. The Monte Carlo method is implemented for both the three-dimensional particle momentum space and the five-dimensional guiding center phase space. Detailed description is provided for both the physics and implementation of the operator. The focus is in adaptive integration of stochastic differential equations, which is an overlooked aspect among existing Monte Carlo implementations of Coulomb collision operators. We verify that our operator converges to known analytical results and demonstrate that careless implementation of the adaptive time step can lead to severely erroneous results. The operator is provided as a self-contained Fortran 95 module and can be included into existing orbit-following tools that trace either the full Larmor motion or the guiding center dynamics. The adaptive time-stepping algorithm is expected to be useful in situations where the collision frequencies vary greatly over the course of a simulation. Examples include the slowing-down of fusion products or other fast ions, and the Dreicer generation of runaway electrons as well as the generation of fast ions or electrons with ion or electron cyclotron resonance heating.

On singlet metastable states, ion flux and ion energy in single and dual frequency capacitively coupled oxygen discharges

NASA Astrophysics Data System (ADS)

Hannesdottir, H.; Gudmundsson, J. T.

2017-05-01

We apply particle-in-cell simulations with Monte Carlo collisions to study the influence of the singlet metastable states on the ion energy distribution in single and dual frequency capacitively coupled oxygen discharges. For this purpose, the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is used, in which the discharge model includes the following nine species: electrons, the neutrals O(3P) and O{{}2}≤ft({{\\text{X}}3} Σ g-\\right. ), the negative ions O-, the positive ions O+ and O2+ , and the metastables O(1D), O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right) and O2(b{{}1} Σ g+ ). Earlier, we have explored the effects of adding the species O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ), and an energy-dependent secondary electron emission yield for oxygen ions and neutrals, to the discharge model. We found that including the two molecular singlet metastable states decreases the ohmic heating and the effective electron temperature in the bulk region (the electronegative core). Here we explore how these metastable states influence dual frequency discharges consisting of a fundamental frequency and the lowest even harmonics. Including or excluding the detachment reactions of the metastables O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ) can shift the peak electron temperature from the grounded to the powered electrode or vice versa, depending on the phase difference of the two applied frequencies. These metastable states can furthermore significantly influence the peak of the ion energy distribution for O2+ -ions bombarding the powered electrode, and hence the average ion energy upon bombardment of the electrode, and lower the ion flux.

Ion-Flow-Induced Excitation of Electrostatic Cyclotron Mode in Magnetized Dusty Plasma

NASA Astrophysics Data System (ADS)

Bezbaruah, P.; Das, N.

2018-05-01

The stability of electrostatic cyclotron mode is investigated in a flowing magnetized dusty plasma in the presence of strong ion-neutral collisions. In the high magnetic field limit, when the dust magnetization becomes important, it is expected that the collective behavior of magnetized dust grains suspended in the near-sheath region substantially influences the dispersion properties of electrostatic modes. The growth/damping of the collective excitation is significantly controlled by such parameters as the ion-neutral collision frequency, Mach number, and magnetic field strength. In our case, the explicit dependence of the Mach number on the magnetic field and collision frequency has been taken into account and possible implications on the stability of the mode is analyzed. Streaming instability of cyclotron modes may be important to understand issues related to the interaction mechanism between dust grains and other associated phenomena like Coulomb crystallization, phase behavior, transport properties, etc., in the relatively strong magnetic field limit, which is currently accessible in the DPD (Kiel University) and MDPX (PSL, Auburn University) experiments.

Modification of electromagnetic fields and plasma resistance by thermal effects in helicon plasmas

NASA Astrophysics Data System (ADS)

Kabir, M.; Niknam, A. R.

2017-05-01

The effects of the thermal motion of charged particles on physical characteristics of collisional helicon plasmas are investigated. First, the dielectric permittivity tensor of a helicon plasma is obtained by considering the thermal and collisional effects in the kinetic theory. Then, the electromagnetic wave and plasma resistance equations are presented and solved in a helicon plasma source with a Nagoya type III antenna. It is shown that by increasing the temperature of plasma electrons, the effective collision frequency is increased, and consequently, the peaks of resistance profiles are lowered and broadened.

Emission characteristics of 6.78-MHz radio-frequency glow discharge plasma in a pulsed mode

NASA Astrophysics Data System (ADS)

Zhang, Xinyue; Wagatsuma, Kazuaki

2017-07-01

This paper investigated Boltzmann plots for both atomic and ionic emission lines of iron in an argon glow discharge plasma driven by 6.78-MHz radio-frequency (RF) voltage in a pulsed operation, in order to discuss how the excitation/ionization process was affected by the pulsation. For this purpose, a pulse frequency as well as a duty ratio of the pulsed RF voltage was selected as the experimenter parameters. A Grimm-style radiation source was employed at a forward RF power of 70 W and at an argon pressures of 670 Pa. The Boltzmann plot for low-lying excited levels of iron atom was on a linear relationship, which was probably attributed to thermal collisions with ultimate electrons in the negative glow region; in this case, the excitation temperature was obtained in a narrow range of 3300-3400 K, which was hardly affected by the duty ratio as well as the pulse frequency of the pulsed RF glow discharge plasma. This observation suggested that the RF plasma could be supported by a self-stabilized negative glow region, where the kinetic energy distribution of the electrons would be changed to a lesser extent. Additional non-thermal excitation processes, such as a Penning-type collision and a charge-transfer collision, led to deviations (overpopulation) of particular energy levels of iron atom or iron ion from the normal Boltzmann distribution. However, their contributions to the overall excitation/ionization were not altered so greatly, when the pulse frequency or the duty ratio was varied in the pulsed RF glow discharge plasma.

Calculation of far wing of allowed spectra: The water continuum

NASA Technical Reports Server (NTRS)

Tipping, R. H.; Ma, Q.

1995-01-01

A far-wing line shape theory based on the binary collision and quasistatic approximations that is applicable for both the low- and high-frequency wings of allowed vibrational-rotational lines has been developed. This theory has been applied in order to calculate the frequency and temperature dependence of the continuous absorption coefficient for frequencies up to 10,000 cm(exp -1) for pure H2O and for H2O-N2 mixtures. The calculations are made assuming an interaction potential consisting of an isotropic Lennard-Jones part and the leading long-range anisotropic part, and utilizing the measured line strengths and transition frequencies. The results compare well with existing data, both in magnitude and in temperature dependence. This leads us to the conclusion that although dimer and collision-induced absorptions are present, the primary mechanism responsible for the observed water continuum is the far-wing absorption of allowed lines. Recent progress on near-wing corrections to the theory and validations with recent laboratory measurements are discussed briefly.

ECRH and its effects on neoclassical transport in a stellarator

NASA Astrophysics Data System (ADS)

Seol, Jaechun

The banana center orbit deviates significantly from the magnetic surface due to the symmetry-breaking term in the magnetic field configuration. Energetic electrons can escape the plasma without collision, since the drift speed is proportional to the perpendicular energy of electron and the collision frequency is reduced as the electron energy goes up. A direct loss flux can be generated from energetic electron population in a stellarator. Thus energetic electron populations can substantially modify the neoclassical transport properties in stellarators. A model accounting for this change in transport is developed assuming the presence of electron cyclotron resonance heating (ECRH). The quasilinear diffusion coefficient for second harmonic X-mode ECRH is developed for a bumpy stellarator. Care is taken in accounting for the pitch-angle dependence of the quasilinear diffusion coefficient since application to experiments with narrow resonance zones is of interest. Weakly relativistic effects are considered through the mass effect on the cyclotron frequency. For trapped particles in a three dimensional configuration, collisionless loss zones exist in velocity space. Radio-frequency (rf) waves accelerate trapped electrons into the direct loss zone in bumpy stellarators and produce a direct loss flux. An analytic expression for this loss flux is derived; it is proportional to the rf field strength and the value of the zeroth order distribution function at the minimum speed for collisionless loss. The direct loss flux of electrons is another source of a non-ambipolar particle flux in bumpy stellarators. This additional non-ambipolar flux modifies the ambipolarity equation which generally has multiple roots for the radial electric field. An electron root (large positive Er) is easily obtained if the electrons are in the 1/nu regime and the ions are in the nu regime.

Ion acoustic shock wave in collisional equal mass plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adak, Ashish, E-mail: ashish-adak@yahoo.com; Ghosh, Samiran, E-mail: sran-g@yahoo.com; Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in

The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipationmore » that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.« less

Collision-induced rotation in an arc-continent collision: Constrained by continuous GPS observations in Mindoro, Philippines

NASA Astrophysics Data System (ADS)

Rau, R.; Hung, H.; Yang, C.; Tsai, M.; Ching, K.; Bacolcol, T.; Solidum, R.; Chang, W.

2012-12-01

The Mindoro Island, situated at the southern end of the Manila trench, is a modern arc-continent collision. Seismic activity in Mindoro concentrates mainly in the northern segment of the island as part of the Manila subduction processes; in contrast, seismicity in the middle and the southern parts of the island is rather diffuse. Although the Mindoro Island has been experiencing intense seismic activities and is a type example of arc-continent collision, the modern mode of deformation of the Mindoro collision remains unclear. We have installed eight dual-frequency continuous GPS stations in the island since May 2010. The questions we want to address by using continuous GPS observations are (1) if there are still compressions within the Mindoro collision? Have they ceased as seen by the diffuse seismicity, or are the thrust faults locked? (2) What is the mode of deformation in the Mindoro collision and what are the roles of thrust and strike-slip faults playing in the collision? (3) How does the Mindoro collision compare with the other collision, such as the Taiwan orogen? Do they share similar characteristics for the subduction-collision transition zone? For the results of the first two years GPS measurements, if we take the Sablayan site near the southern end of the Manila trench as the reference station, a large counterclockwise rotation from south to north, with horizontal velocities of 1.9-31.1 mm/yr from 165 to 277 degrees, are found in the island. The deformation of the Mindoro is similar to the pattern of the transition zone from collision to subduction in northeastern Taiwan. This result suggests that collision-induced rotation is occurring in the Mindoro Island and the Mindoro arc-continent collision is still active.

Hydrodynamic effects and receptor interactions of platelets and their aggregates in linear shear flow.

PubMed Central

Tandon, P; Diamond, S L

1997-01-01

We have modeled platelet aggregation in a linear shear flow by accounting for two body collision hydrodynamics, platelet activation and receptor biology. Considering platelets and their aggregates as unequal-sized spheres with DLVO interactions (psi(platelet) = -15 mV, Hamaker constant = 10(-19) J), detailed hydrodynamics provided the flow field around the colliding platelets. Trajectory calculations were performed to obtain the far upstream cross-sectional area and the particle flux through this area provided the collision frequency. Only a fraction of platelets brought together by a shearing fluid flow were held together if successfully bound by fibrinogen cross-bridging GPIIb/IIIa receptors on the platelet surfaces. This fraction was calculated by modeling receptor-mediated aggregation using the formalism of Bell (Bell, G. I. 1979. A theoretical model for adhesion between cells mediated by multivalent ligands. Cell Biophys. 1:133-147) where the forward rate of bond formation dictated aggregation during collision and was estimated from the diffusional limited rate of lateral association of receptors multiplied by an effectiveness factor, eta, to give an apparent rate. For a value of eta = 0.0178, we calculated the overall efficiency (including both receptor binding and hydrodynamics effects) for equal-sized platelets with 50,000 receptors/platelet to be 0.206 for G = 41.9 s(-1), 0.05 for G = 335 s(-1), and 0.0086 for G = 1920 s(-1), values which are in agreement with efficiencies determined from initial platelet singlet consumption rates in flow through a tube. From our analysis, we predict that bond formation proceeds at a rate of approximately 0.1925 bonds/microm2 per ms, which is approximately 50-fold slower than the diffusion limited rate of association. This value of eta is also consistent with a colloidal stability of unactivated platelets at low shear rates. Fibrinogen was calculated to mediate aggregation quite efficiently at low shear rates but not at high shear rates. Although secondary collisions (an orbitlike trajectory) form only a small fraction of the total number of collisions, they become important at high shear rates (>750 s(-1)), as these are the only collisions that provide enough time to result in successful aggregate formation mediated by fibrinogen. The overall method provides a hydrodynamic and receptor correction of the Smoluchowski collision kernel and gives a first estimate of eta for the fibrinogen-GPIIb/IIIa cross-bridging of platelets. We also predict that secondary collisions extend the shear rate range at which fibrinogen can mediate successful aggregation. Images FIGURE 2 PMID:9370476

Is there a link between motor vehicle collisions and being a cigarette smoker in Canada? Analysis of survey data from Ontario from 2002 to 2014.

PubMed

Vingilis, Evelyn; Pederson, Linda L; Seeley, Jane; Ialomiteanu, Anca R; Wickens, Christine M; Ferrence, Roberta; Mann, Robert E

2018-05-19

Although most research on drugs and driving has focused on the use of alcohol and cannabis, research that has been conducted on cigarette smoking and collisions has found that smokers have an increased collision involvement. Studies dating from 1967 through 2013 have shown a crude relative risk of about 1.5 among smokers compared to nonsmokers. In Canada, the association between smoking and collisions has not been recently investigated. Studies that have examined the association between smoking and collisions often did not control for all confounding factors, such as alcohol use and driving exposure, which have been associated with increased collision rates. Additionally, a number of these studies were examined in countries and at times when prevalence of smoking was much higher than is currently the case in Canada. The purpose of this research is to examine the association between self-reported current smoking and past-year collision involvement, controlling for confounding factors, in a large representative sample of adult drivers in Ontario, Canada, from 2002 and 2014. Data are based on the Centre for Addiction and Mental Health (CAMH) Monitor, an ongoing, rolling telephone survey of Ontario adults that provides epidemiological surveillance of indicators related to alcohol, tobacco, and other drug use, as well as physical and mental health. The survey uses random-digit-dialing methods via Computer-Assisted Telephone Interview, with response rates over 50%. Prevalence of self-reported collision involvement within the past year for 2002-2014 was 8.6% among those who currently smoke compared to 6.5% of nonsmokers. Logistic regression analysis, controlling for the potential confounding effects of sociodemographics, driving exposure measures, drinking frequency, and hazardous alcohol use, found that the overall odds for collision involvement in the preceding year among current smokers for 2002-2014 was 1.27 (95% confidence interval [CI], 1.06-1.53) times that of nonsmokers. These findings indicate that despite a substantial reduction in overall prevalence of smoking in Canada, smokers still have a significantly increased odds of collision involvement, even when controlling for alcohol and exposure. Additionally, the results are consistent with the increased odds/risks of motor vehicle collisions found in other countries.

Sonic Simulation of Near Projectile Hits

NASA Technical Reports Server (NTRS)

Statman, J. I.; Rodemich, E. R.

1988-01-01

Measured frequencies identify projectiles and indicate miss distances. Developmental battlefield-simulation system for training soldiers uses sounds emitted by incoming projectiles to identify projectiles and indicate miss distances. Depending on projectile type and closeness of each hit, system generates "kill" or "near-kill" indication. Artillery shell simulated by lightweight plastic projectile launched by compressed air. Flow of air through groove in nose of projectile generates acoustic tone. Each participant carries audio receiver measure and process tone signal. System performs fast Fourier transforms of received tone to obtain dominant frequency during each succeeding interval of approximately 40 ms (an interval determined from practical signal-processing requirements). With modifications, system concept applicable to collision-warning or collision-avoidance systems.

Coagulation processes of kaolinite and montmorillonite in calm, saline water

NASA Astrophysics Data System (ADS)

Zhang, Jin-Feng; Zhang, Qing-He; Maa, Jerome P.-Y.

2018-03-01

A three dimensional numerical model for simulating the coagulation processes of colloids has been performed by monitoring the time evolution of particle number concentration, the size distribution of aggregates, the averaged settling velocity, the collision frequency, and the collision efficiency in quiescent water with selected salinities. This model directly simulates all interaction forces between particles based on the lattice Boltzmann method (LBM) and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and thus, can reveal the collision and coagulation processes of colloidal suspensions. Although using perfect spherical particles in the modeling, the results were compared with those for kaolinite and montmorillonite suspensions to demonstrate the capability of simulating the responses of these particles with highly irregular shape. The averaged settling velocity of kaolinite aggregates in quiescent saline water reached a maximum of 0.16 mm/s when the salinity increasing to about 3, and then, exhibited little dependence on salinity thereafter. Model simulations results (by choosing specific values that represent kaolinite's characteristics) indicate a similar trend: rapid decrease of the particle number concentration (i.e., rapidly flocculated, and thus, settling velocity also increases rapidly) when salinity increases from 0 to 2, and then, only increased slightly when salinity was further increased from 5 to 20. The collision frequency for kaolinite only decreases slightly with increasing salinity because that the fluid density and viscosity increase slightly in sea water. It suggests that the collision efficiency for kaolinite rises rapidly at low salinities and levels off at high salinity. For montmorillonite, the settling velocity of aggregates in quiescent saline water continuedly increases to 0.022 mm/s over the whole salinity range 0-20, and the collision efficiency for montmorillonite rises with increasing salinities.

47 CFR 87.349 - Frequencies.

Code of Federal Regulations, 2014 CFR

2014-10-01

... for ground vehicle identification and collision avoidance; (3) No more than two hundred 1090 MHz... utility station at an airport served by a control tower, RCO or FAA flight service station is the frequency used by the control tower for ground traffic control or by the flight service station for...

Development of a fluidized bed agglomeration modeling methodology to include particle-level heterogeneities in ash chemistry and granular physics

NASA Astrophysics Data System (ADS)

Khadilkar, Aditi B.

The utility of fluidized bed reactors for combustion and gasification can be enhanced if operational issues such as agglomeration are mitigated. The monetary and efficiency losses could be avoided through a mechanistic understanding of the agglomeration process and prediction of operational conditions that promote agglomeration. Pilot-scale experimentation prior to operation for each specific condition can be cumbersome and expensive. So the development of a mathematical model would aid predictions. With this motivation, the study comprised of the following model development stages- 1) development of an agglomeration modeling methodology based on binary particle collisions, 2) study of heterogeneities in ash chemical composition and gaseous atmosphere, 3) computation of a distribution of particle collision frequencies based on granular physics for a poly-disperse particle size distribution, 4) combining the ash chemistry and granular physics inputs to obtain agglomerate growth probabilities and 5) validation of the modeling methodology. The modeling methodology comprised of testing every binary particle collision in the system for sticking, based on the extent of dissipation of the particles' kinetic energy through viscous dissipation by slag-liquid (molten ash) covering the particles. In the modeling methodology developed in this study, thermodynamic equilibrium calculations are used to estimate the amount of slag-liquid in the system, and the changes in particle collision frequencies are accounted for by continuously tracking the number density of the various particle sizes. In this study, the heterogeneities in chemical composition of fuel ash were studied by separating the bulk fuel into particle classes that are rich in specific minerals. FactSage simulations were performed on two bituminous coals and an anthracite to understand the effect of particle-level heterogeneities on agglomeration. The mineral matter behavior of these constituent classes was studied. Each particle class undergoes distinct transformations of mineral matter at fluidized bed operating temperatures, as determined by using high temperature X-ray diffraction, thermo-mechanical analysis and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). For the incorporation of a particle size distribution, bottom ash from an operating plant was divided into four size intervals and the system granular temperatures and dynamic bed height were computed using MFIX, a CFD simulation software. The kinetic theory of granular flow was used to obtain a distribution of binary collision frequencies for the entire particle size distribution. With this distribution of collision frequencies, which is computed based on hydrodynamics and granular physics of the poly-disperse system, as the particles grow, defluidize and decrease in number, the collision frequency also decreases. Under the conditions studied, the growth rate in the latter half of the run decreased to almost 1/5th the initial rate, with this decrease in collision frequency. This interdependent effect of chemistry and physics-based parameters, at the particle-level, was used to predict the agglomerate growth probabilities of Pittsburgh No. 8, Illinois No. 6 and Skidmore anthracite coals in this study, to illustrate the utility of the modeling methodology. The study also showed that agglomerate growth probability significantly increased above 15 to 20 wt. % slag. It was limited by ash chemistry at levels below this amount. Ash agglomerates were generated in a laboratory-scale fluidized bed combustor at Penn State to support the proposed agglomerate growth mechanism. This study also attempted to gain a mechanistic understanding of agglomerate growth with particle-level initiation occurring at the relatively low operating temperatures of about 950 °C, found in some fluidized beds. The results of this study indicated that, for the materials examined, agglomerate growth in fluidized bed combustors and gasifiers is initiated at the particle-level by low-melting components rich in iron- and calcium-based minerals. Although the bulk ash chemical composition does not indicate potential for agglomeration, study of particle-level heterogeneities revealed that agglomeration can begin at lower temperatures than the fluidized bed operating temperatures of 850 °C. After initiation at the particle-level, more slag is observed to form from alumino-silicate components at about 50 to 100 °C higher temperatures caused by changes in the system, and agglomerate growth propagates in the bed. A post-mortem study of ash agglomerates using SEM-EDX helped to identify stages of agglomerate growth. Additionally, the modeling methodology developed was used to simulate agglomerate growth in a laboratory-scale fluidized bed combustor firing palm shells (biomass), reported in the literature. A comparison of the defluidization time obtained by simulations to the experimental values reported in the case-study was made for the different operating conditions studied. This indicated that although the simulation results were comparable to those reported in the case study, modifications such as inclusion of heat transfer calculations to determine particle temperature resulting from carbon conversion would improve the predictive capabilities. (Abstract shortened by ProQuest.).

Hybrid Alfven resonant mode generation in the magnetosphere-ionosphere coupling system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiraki, Yasutaka; Watanabe, Tomo-Hiko

2012-10-15

Feedback unstable Alfven waves involving global field-line oscillations and the ionospheric Alfven resonator (IAR) were comprehensively studied to clarify their properties of frequency dispersion, growth rate, and eigenfunctions. It is discovered that a new mode called here the hybrid Alfven resonant (HAR) mode can be destabilized in the magnetosphere-ionosphere coupling system with a realistic Alfven velocity profile. The HAR mode found in a high frequency range over 0.3 Hz is caused by coupling of IAR modes with strong dispersion and magnetospheric cavity resonances. The harmonic relation of HAR eigenfrequencies is characterized by a constant frequency shift from those of IARmore » modes. The three modes are robustly found even if effects of two-fluid process and ionospheric collision are taken into account and thus are anticipated to be detected by magnetic field observations in a frequency range of 0.3-1 Hz in auroral and polar-cap regions.« less

Highly Efficient Transmitter for High Peak to Average Power Ratio (PAPR) Waveforms

DTIC Science & Technology

2011-01-19

on the modulated signal topology. N00039-10-C-0071 Page 1 ACRONYM DESCRIPTION FREQUENCY Lower Upper MHz MHz ACAS Avionics Identification ...450 GSM Global Mobile Communications 380 921 HAVE QUICK Military Aircraft Radio 225 400 IFF Avionics Identification . Collision Avoidance and...Channel Ground Air Radio System 30 88 TCAS Avionics Identification , Collision Avoidance and Traffic Alert 1030 1090 VIII Air Traffic Control (Civilian

Survival condition for low-frequency quasi-one-dimensional breathers in a two-dimensional strongly anisotropic crystal

NASA Astrophysics Data System (ADS)

Savin, A. V.; Zubova, E. A.; Manevitch, L. I.

2005-06-01

We investigate a two-dimensional (2D) strongly anisotropic crystal (2D SAC) on substrate: 2D system of coupled linear chains of particles with strong intrachain and weak interchain interactions, each chain being subjected to the sine background potential. Nonlinear dynamics of one of these chains when the rest of them are fixed is reduced to the well known Frenkel-Kontorova (FK) model. Depending on strengh of the substrate, the 2D SAC models a variety of physical systems: polymer crystals with identical chains having light side groups, an array of inductively coupled long Josephson junctions, anisotropic crystals having light and heavy sublattices. Continuum limit of the FK model, the sine-Gordon (sG) equation, allows two types of soliton solutions: topological solitons and breathers. It is known that the quasi-one-dimensional topological solitons can propagate also in a chain of 2D system of coupled chains and even in a helix chain in a three-dimensional model of polymer crystal. In contrast to this, numerical simulation shows that the long-living breathers inherent to the FK model do not exist in the 2D SAC with weak background potential. The effect changes scenario of kink-antikink collision with small relative velocity: at weak background potential the collision always results only in intensive phonon radiation while kink-antikink recombination in the FK model results in long-living low-frequency sG breather creation. We found the survival condition for breathers in the 2D SAC on substrate depending on breather frequency and strength of the background potential. The survival condition bears no relation to resonances between breather frequency and frequencies of phonon band—contrary to the case of the FK model.

Mid-IR femtosecond frequency conversion by soliton-probe collision in phase-mismatched quadratic nonlinear crystals.

PubMed

Liu, Xing; Zhou, Binbin; Guo, Hairun; Bache, Morten

2015-08-15

We show numerically that ultrashort self-defocusing temporal solitons colliding with a weak pulsed probe in the near-IR can convert the probe to the mid-IR. A near-perfect conversion efficiency is possible for a high effective soliton order. The near-IR self-defocusing soliton can form in a quadratic nonlinear crystal (beta-barium borate) in the normal dispersion regime due to cascaded (phase-mismatched) second-harmonic generation, and the mid-IR converted wave is formed in the anomalous dispersion regime between λ=2.2-2.4  μm as a resonant dispersive wave. This process relies on nondegenerate four-wave mixing mediated by an effective negative cross-phase modulation term caused by cascaded soliton-probe sum-frequency generation.

A review of tags anti-collision and localization protocols in RFID networks.

PubMed

Ullah, S; Alsalih, W; Alsehaim, A; Alsadhan, N

2012-12-01

Radio Frequency IDentification (RFID) has allowed the realization of ubiquitous tracking and monitoring of physical objects wirelessly with minimum human interactions. It plays a key role in a wide range of applications including asset tracking, contactless payment, access control, transportation and logistics, and other industrial applications. On the other side, RFID systems face several technical challenges that need to be overcome in order to achieve their potential benefits; tags collisions and localization of tagged objects are two important challenges. Numerous anti-collision and localization protocols have been proposed to address these challenges. This paper reviews the state-of-art tags' anti-collision and localization protocols, and provides a deep insight into technical issues of these protocols. The probabilistic and deterministic anti-collision protocols are critically studied and compared in terms of different parameters. We further review distance estimation, scene analysis, and proximity localization schemes and provide useful suggestions. We also introduce a new hybrid direction that utilizes power control to spatially partition the interrogation range of a reader for more efficient anti-collision and localization. Finally, we present the applications of RFID systems in healthcare sectors.

Secondary Collisions Following a Traffic Barrier Impact: Frequency, Factors, and Occupant Risk

PubMed Central

Gabauer, Douglas J.

2010-01-01

This study has investigated secondary collisions following an initial barrier impact in tow-away level crashes. The analysis included 2026 barrier impact cases that were selected from 12-years of in-depth crash data available through the National Automotive Sampling System (NASS) / Crashworthiness Data System (CDS). Secondary collisions were found to occur in approximately one-third of tow-away level crashes where a traffic barrier was the first object struck. Secondary crashes were found to primarily involve an impact to another vehicle, an impact to another barrier, or a rollover; tree and pole impacts were found to represent a much smaller proportion of secondary impacts. Through a detailed analysis of vehicle trajectory, this study supports previous research suggesting secondary collision risk is substantial even for vehicles not ultimately involved in a secondary collision. Compared to a single barrier impact, the occurrence of a secondary collision was found to increase the risk of serious occupant injury by a factor of 3.5, equivalent to the serious injury risk difference found between a belted and unbelted occupant in a traffic barrier crash. PMID:21050605

Electrochemical detection of a single cytomegalovirus at an ultramicroelectrode and its antibody anchoring

PubMed Central

Dick, Jeffrey E.; Hilterbrand, Adam T.; Boika, Aliaksei; Upton, Jason W.; Bard, Allen J.

2015-01-01

We report observations of stochastic collisions of murine cytomegalovirus (MCMV) on ultramicroelectrodes (UMEs), extending the observation of discrete collision events on UMEs to biologically relevant analytes. Adsorption of an antibody specific for a virion surface glycoprotein allowed differentiation of MCMV from MCMV bound by antibody from the collision frequency decrease and current magnitudes in the electrochemical collision experiments, which shows the efficacy of the method to size viral samples. To add selectivity to the technique, interactions between MCMV, a glycoprotein-specific primary antibody to MCMV, and polystyrene bead “anchors,” which were functionalized with a secondary antibody specific to the Fc region of the primary antibody, were used to affect virus mobility. Bead aggregation was observed, and the extent of aggregation was measured using the electrochemical collision technique. Scanning electron microscopy and optical microscopy further supported aggregate shape and extent of aggregation with and without MCMV. This work extends the field of collisions to biologically relevant antigens and provides a novel foundation upon which qualitative sensor technology might be built for selective detection of viruses and other biologically relevant analytes. PMID:25870261

Doppler extraction with a digital VCO

NASA Technical Reports Server (NTRS)

Starner, E. R.; Nossen, E. J.

1977-01-01

Digitally controlled oscillator in phased-locked loop may be useful for data communications systems, or may be modified to serve as information extraction component of microwave or optical system for collision avoidance or automatic braking. Instrument is frequency-synthesizing device with output specified precisely by digital number programmed into frequency register.

High Energy Research and Applications (HERA) Pulsed Power and Pulsed Power Systems R&D for Magnetized Target Fusion Using Field Reversed Configurations (MTF-FRC)

DTIC Science & Technology

2013-03-12

electron collision frequency, given, in cgs units, by [17] ( ) 4 23 4 3 en kTm ee e λπ τ = . (2) Here, Te is the electron temperature, in eV, k = 1.6x10...acceleration, in the absence of collisions, is given by - eE /me. To take electron-neutral collisions into account20, we note that the average time between...time being, the continuity equation is 298 Approved for public release; distribution is unlimited. eee nDt n 2∇= ∂ ∂ , (21) which is the

Daylight saving time can decrease the frequency of wildlife–vehicle collisions

PubMed Central

Ellis, William A.; FitzGibbon, Sean I.; Barth, Benjamin J.; Niehaus, Amanda C.; David, Gwendolyn K.; Taylor, Brendan D.; Matsushige, Helena; Melzer, Alistair; Bercovitch, Fred B.; Carrick, Frank; Jones, Darryl N.; Dexter, Cathryn; Gillett, Amber; Predavec, Martin; Lunney, Dan

2016-01-01

Daylight saving time (DST) could reduce collisions with wildlife by changing the timing of commuter traffic relative to the behaviour of nocturnal animals. To test this idea, we tracked wild koalas (Phascolarctos cinereus) in southeast Queensland, where koalas have declined by 80% in the last 20 years, and compared their movements with traffic patterns along roads where they are often killed. Using a simple model, we found that DST could decrease collisions with koalas by 8% on weekdays and 11% at weekends, simply by shifting the timing of traffic relative to darkness. Wildlife conservation and road safety should become part of the debate on DST. PMID:27881767

Effect of velocity-dependent friction on multiple-vehicle collisions in traffic flow

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

2017-01-01

We present the dynamic model for the multiple-vehicle collisions to take into account the velocity-dependent friction force. We study the effect of the velocity-dependent friction on the chain-reaction crash on a road. In the traffic situation, drivers brake according to taillights of the forward vehicle and the friction force depends highly on the vehicular speed. The first crash may induce more collisions. We investigate whether or not the first collision induces the multiple-vehicle collisions, numerically and analytically. The dynamic transitions occur from no collisions, through a single collision and double collisions, to multiple collisions with decreasing the headway. We explore the effect of the velocity-dependent friction on the dynamic transitions and the region maps in the multiple-vehicle collisions.

Exploring the impact of a dedicated streetcar right-of-way on pedestrian motor vehicle collisions: a quasi experimental design.

PubMed

Richmond, Sarah A; Rothman, Linda; Buliung, Ron; Schwartz, Naomi; Larsen, Kristian; Howard, Andrew

2014-10-01

The frequency of pedestrian collisions is strongly influenced by the built environment, including road width, street connectivity and public transit design. In 2010, 2159 pedestrian collisions were reported in the City of Toronto, Canada with 20 fatalities. Previous studies have reported that streetcars operating in mixed traffic pose safety risks to pedestrians; however, few studies evaluate the effects on pedestrian-motor vehicle collisions (PMVC). The objective of this study was to examine changes in the rate and spatial patterning of PMVC, pre to post right-of-way (ROW) installation of the St. Clair Avenue West streetcar in the City of Toronto, Canada. A quasi-experimental design was used to evaluate changes in PMVC rate, following implementation of a streetcar ROW. Collision data were extracted from all police-reported PMVC, complied and verified by the City of Toronto, from January 1, 2000 to December 31, 2011. A zero-inflated Poisson regression analysis estimated the change in PMVC, pre to post ROW. Age and injury severity were also examined. Changes in the spatial pattern of collisions were examined by applying the G function to describe the proportion of collision events that shared a nearest neighbor distance less than or equal to a threshold distance. A total of 23,607 PMVC occurred on roadways during the study period; 441 occurring on St. Clair Ave, 153 during the period of analysis. There was a 48% decrease in the rate of collisions on St. Clair [Incidence rate ratio (IRR)=0.52, 95% CI: 0.37-0.74], post ROW installation. There were also decreases noted for children (IRR=0.13, 95% CI: 0.04-0.44), adults (IRR=0.61, 95% CI: 0.38-0.97), and minor injuries (IRR=0.56, 95% CI: 0.40-0.80). Spatial analyses indicated increased dispersion of collision events across each redeveloped route segment following the changes in ROW design. Construction of a raised ROW operating on St. Clair Ave. was associated with a reduction in the rate of collisions. Differences in pre- and post collision spatial structure indicated changes in collision locations. Results from this study suggest that a streetcar ROW may be a safer alternative for pedestrians compared to a mixed traffic streetcar route and should be considered by city planners where appropriate to the street environment. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

The effect of zero-point energy differences on the isotope dependence of the formation of ozone: a classical trajectory study.

PubMed

Schinke, Reinhard; Fleurat-Lessard, Paul

2005-03-01

The effect of zero-point energy differences (DeltaZPE) between the possible fragmentation channels of highly excited O(3) complexes on the isotope dependence of the formation of ozone is investigated by means of classical trajectory calculations and a strong-collision model. DeltaZPE is incorporated in the calculations in a phenomenological way by adjusting the potential energy surface in the product channels so that the correct exothermicities and endothermicities are matched. The model contains two parameters, the frequency of stabilizing collisions omega and an energy dependent parameter Delta(damp), which favors the lower energies in the Maxwell-Boltzmann distribution. The stabilization frequency is used to adjust the pressure dependence of the absolute formation rate while Delta(damp) is utilized to control its isotope dependence. The calculations for several isotope combinations of oxygen atoms show a clear dependence of relative formation rates on DeltaZPE. The results are similar to those of Gao and Marcus [J. Chem. Phys. 116, 137 (2002)] obtained within a statistical model. In particular, like in the statistical approach an ad hoc parameter eta approximately 1.14, which effectively reduces the formation rates of the symmetric ABA ozone molecules, has to be introduced in order to obtain good agreement with the measured relative rates of Janssen et al. [Phys. Chem. Chem. Phys. 3, 4718 (2001)]. The temperature dependence of the recombination rate is also addressed.

Studies of Inelastic Collisions of NaK and NaCs Molecules with Atomic Perturbers

NASA Astrophysics Data System (ADS)

Jones, Joshua A.

We have investigated collisions of NaK molecules in the first excited state [2(A)1Sigma+], with Ar and He collision partners using laser-induced fluorescence spectroscopy (LIF) and polarization-labeling (PL) spectroscopy in a two-step excitation scheme. Additionally, we have investigated collisions of NaCs molecules in the first excited state [2(A)1Sigma +] with Ar and He perturbers using the LIF technique. We use a pump-probe, two-step excitation process. The pump laser prepares the molecule in a particular ro-vibrational (v, J) level in the A state. The probe laser frequency is scanned over transitions to the 31Π in NaK or to the 53Π in NaCs. In addition to observing strong direct lines, we also see weak collisional satellite lines that arise from collisions in the intermediate state that take the molecule from the prepared level (v, J) to level (v, J + Delta J). The ratio of the intensity of the collisional line to the intensity of the direct line in LIF and PL yield information about population and orientation transfer. Our results show a propensity for DeltaJ=even collisions of NaK with Ar and an even stronger propensity for collisions with He. Collisions of NaCs with Ar do not show any such J=even propensity. Preliminary investigations of collisions of NaCs with He seem to indicate a slight J=even propensity. In addition, we observe that rotationally inelastic collisions of excited NaK molecules with potassium atoms destroy almost all of the orientation, while collisions with argon destroy about one third to two thirds and collisions with helium destroy only about zero to one third of the initial orientation.

Electrical Characteristics, Electrode Sheath and Contamination Layer Behavior of a Meso-Scale Premixed Methane-Air Flame Under AC/DC Electric Fields

NASA Astrophysics Data System (ADS)

Chen, Qi; Yan, Limin; Zhang, Hao; Li, Guoxiu

2016-05-01

Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC (0-4300 V, 0-500 Hz) and DC (0-3300 V) electric fields were studied. I-V curves were measured under different experimental conditions to estimate the magnitude of the total current 100-102 μA, the electron density 1015-1016 m-3 and further the power dissipation ≤ 0.7 W in the reaction zone. At the same time, the meso-scale premixed flame conductivity 10-4-10-3 Ω-1·m-1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitude estimate. Moreover, the influence of the collision sheath relating to Debye length (31-98 μm) and the contamination layer of an active electrode on measurements was discussed, based on the combination of simulation and theoretical analysis. As a result, the electrode sheath dimension was evaluated to less than 0.5 mm, which indicated a complex effect of the collision sheath on the current measurements. The surface contamination effect of an active electrode was further analyzed using the SEM imaging method, which showed elements immigration during the contamination layer formation process. supported by National Natural Science Foundation of China (No. 51376021), and the Fundamental Research Fund for Major Universities (No. 2013JBM079)

Thermal Ion Upwelling in the High-Altitude Ionosphere

DTIC Science & Technology

1990-01-01

hard sphere collisions) while Vst is the momentum transfer collision frequency between all the other species t and a single s species particle. For... angular dimensions of day side entrance region off of Od degrees towards evening Od angular dimensions of day side entrance region off of 0d...degrees towards morning + angular dimensions of night side exit region off of on towards degrees On degre morning On angular dimensions of night side exit

Probe-controlled soliton frequency shift in the regime of optical event horizon.

PubMed

Gu, Jie; Guo, Hairun; Wang, Shaofei; Zeng, Xianglong

2015-08-24

In optical analogy of the event horizon, temporal pulse collision and mutual interactions are mainly between an intense solitary wave (soliton) and a dispersive probe wave. In such a regime, here we numerically investigate the probe-controlled soliton frequency shift as well as the soliton self-compression. In particular, in the dispersion landscape with multiple zero dispersion wavelengths, bi-directional soliton spectral tunneling effects is possible. Moreover, we propose a mid-infrared soliton self-compression to the generation of few-cycle ultrashort pulses, in a bulk of quadratic nonlinear crystals in contrast to optical fibers or cubic nonlinear media, which could contribute to the community with a simple and flexible method to experimental implementations.

On nonlinear evolution of low-frequency Alfvén waves in weakly-expanding solar wind plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nariyuki, Y.

A multi-dimensional nonlinear evolution equation for Alfvén waves in weakly-expanding solar wind plasmas is derived by using the reductive perturbation method. The expansion of solar wind plasma parcels is modeled by an expanding box model, which includes the accelerating expansion. It is shown that the resultant equation agrees with the Wentzel-Kramers-Brillouin prediction of the low-frequency Alfvén waves in the linear limit. In the cold and one-dimensional limit, a modified derivative nonlinear Schrodinger equation is obtained. Direct numerical simulations are carried out to discuss the effect of the expansion on the modulational instability of monochromatic Alfvén waves and the propagation ofmore » Alfvén solitons. By using the instantaneous frequency, it is quantitatively shown that as far as the expansion rate is much smaller than wave frequencies, effects of the expansion are almost adiabatic. It is also confirmed that while shapes of Alfvén solitons temporally change due to the expansion, some of them can stably propagate after their collision in weakly-expanding plasmas.« less

Polarization of Sunyaev-Zel'dovich signal due to electron pressure anisotropy in galaxy clusters

NASA Astrophysics Data System (ADS)

Khabibullin, I.; Komarov, S.; Churazov, E.; Schekochihin, A.

2018-02-01

We describe polarization of the Sunyaev-Zel'dovich (SZ) effect associated with electron pressure anisotropy likely present in the intracluster medium (ICM). The ICM is an astrophysical example of a weakly collisional plasma where the Larmor frequencies of charged particles greatly exceed their collision frequencies. This permits formation of pressure anisotropies, driven by evolving magnetic fields via adiabatic invariance, or by heat fluxes. SZ polarization arises in the process of Compton scattering of the cosmic microwave background (CMB) photons off the thermal ICM electrons due to the difference in the characteristic thermal velocities of the electrons along two mutually orthogonal directions in the sky plane. The signal scales linearly with the optical depth of the region containing large-scale correlated anisotropy, and with the degree of anisotropy itself. It has the same spectral dependence as the polarization induced by cluster motion with respect to the CMB frame (kinematic SZ effect polarization), but can be distinguished by its spatial pattern. For the illustrative case of a galaxy cluster with a cold front, where electron transport is mediated by Coulomb collisions, we estimate the CMB polarization degree at the level of 10-8 (˜10 nK). An increase of the effective electron collisionality due to plasma instabilities will reduce the effect. Such polarization, therefore, may be an independent probe of the electron collisionality in the ICM, which is one of the key properties of a high-β weakly collisional plasma from the point of view of both astrophysics and plasma theory.

An investigation of Ar metastable state density in low pressure dual-frequency capacitively coupled argon and argon-diluted plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wen-Yao; Xu, Yong, E-mail: yongxu@dlut.edu.cn; Peng, Fei

2015-01-14

An tunable diode laser absorption spectroscopy has been used to determine the Ar*({sup 3}P{sub 2}) and Ar*({sup 3}P{sub 0}) metastable atoms densities in dual-frequency capacitively coupled plasmas. The effects of different control parameters, such as high-frequency power, gas pressure and content of Ar, on the densities of two metastable atoms and electron density were discussed in single-frequency and dual-frequency Ar discharges, respectively. Particularly, the effects of the pressure on the axial profile of the electron and Ar metastable state densities were also discussed. Furthermore, a simple rate model was employed and its results were compared with experiments to analyze themore » main production and loss processes of Ar metastable states. It is found that Ar metastable state is mainly produced by electron impact excitation from the ground state, and decayed by diffusion and collision quenching with electrons and neutral molecules. Besides, the addition of CF{sub 4} was found to significantly increase the metastable destruction rate by the CF{sub 4} quenching, especially for large CF{sub 4} content and high pressure, it becomes the dominant depopulation process.« less

Frequency of anti-collision observing responses by solo pilots as a function of traffic density, ATC traffic warnings, and competing behavior.

DOT National Transportation Integrated Search

1973-04-01

Eighteen instrument-rated pilots were flown in two-hour simulated solo missions during which the frequency of traffic, ATC warnings, and ATC clearances were varied, while the visibility of the target was held constant at 100%. : In order to observe t...

A model for the kinetics of homotypic cellular aggregation under static conditions

NASA Technical Reports Server (NTRS)

Neelamegham, S.; Munn, L. L.; Zygourakis, K.; McIntire, L. V. (Principal Investigator)

1997-01-01

We present the formulation and testing of a mathematical model for the kinetics of homotypic cellular aggregation. The model considers cellular aggregation under no-flow conditions as a two-step process. Individual cells and cell aggregates 1) move on the tissue culture surface and 2) collide with other cells (or aggregates). These collisions lead to the formation of intercellular bonds. The aggregation kinetics are described by a system of coupled, nonlinear ordinary differential equations, and the collision frequency kernel is derived by extending Smoluchowski's colloidal flocculation theory to cell migration and aggregation on a two-dimensional surface. Our results indicate that aggregation rates strongly depend upon the motility of cells and cell aggregates, the frequency of cell-cell collisions, and the strength of intercellular bonds. Model predictions agree well with data from homotypic lymphocyte aggregation experiments using Jurkat cells activated by 33B6, an antibody to the beta 1 integrin. Since cell migration speeds and all the other model parameters can be independently measured, the aggregation model provides a quantitative methodology by which we can accurately evaluate the adhesivity and aggregation behavior of cells.

A generalized form of the Bernoulli Trial collision scheme in DSMC: Derivation and evaluation

NASA Astrophysics Data System (ADS)

Roohi, Ehsan; Stefanov, Stefan; Shoja-Sani, Ahmad; Ejraei, Hossein

2018-02-01

The impetus of this research is to present a generalized Bernoulli Trial collision scheme in the context of the direct simulation Monte Carlo (DSMC) method. Previously, a subsequent of several collision schemes have been put forward, which were mathematically based on the Kac stochastic model. These include Bernoulli Trial (BT), Ballot Box (BB), Simplified Bernoulli Trial (SBT) and Intelligent Simplified Bernoulli Trial (ISBT) schemes. The number of considered pairs for a possible collision in the above-mentioned schemes varies between N (l) (N (l) - 1) / 2 in BT, 1 in BB, and (N (l) - 1) in SBT or ISBT, where N (l) is the instantaneous number of particles in the lth cell. Here, we derive a generalized form of the Bernoulli Trial collision scheme (GBT) where the number of selected pairs is any desired value smaller than (N (l) - 1), i.e., Nsel < (N (l) - 1), keeping the same the collision frequency and accuracy of the solution as the original SBT and BT models. We derive two distinct formulas for the GBT scheme, where both formula recover BB and SBT limits if Nsel is set as 1 and N (l) - 1, respectively, and provide accurate solutions for a wide set of test cases. The present generalization further improves the computational efficiency of the BT-based collision models compared to the standard no time counter (NTC) and nearest neighbor (NN) collision models.

Daylight saving time can decrease the frequency of wildlife-vehicle collisions.

PubMed

Ellis, William A; FitzGibbon, Sean I; Barth, Benjamin J; Niehaus, Amanda C; David, Gwendolyn K; Taylor, Brendan D; Matsushige, Helena; Melzer, Alistair; Bercovitch, Fred B; Carrick, Frank; Jones, Darryl N; Dexter, Cathryn; Gillett, Amber; Predavec, Martin; Lunney, Dan; Wilson, Robbie S

2016-11-01

Daylight saving time (DST) could reduce collisions with wildlife by changing the timing of commuter traffic relative to the behaviour of nocturnal animals. To test this idea, we tracked wild koalas (Phascolarctos cinereus) in southeast Queensland, where koalas have declined by 80% in the last 20 years, and compared their movements with traffic patterns along roads where they are often killed. Using a simple model, we found that DST could decrease collisions with koalas by 8% on weekdays and 11% at weekends, simply by shifting the timing of traffic relative to darkness. Wildlife conservation and road safety should become part of the debate on DST. © 2016 The Author(s).

Influence of the Distribution of Tag IDs on RFID Memoryless Anti-Collision Protocols

PubMed Central

Cmiljanic, Nikola; Landaluce, Hugo; Perallos, Asier; Arjona, Laura

2017-01-01

In recent years, Radio Frequency Identification (RFID) has become very popular. The main feature of this technology is that RFID tags do not require close handling and no line of sight is required between the reader and the tags. RFID is a technology that uses radio frequencies in order to identify tags, which do not need to be positioned accurately relative to the reader. Tags share the communication channel, increasing the likelihood of causing a problem, viz., a message collision. Tree based protocols can resolve these collisions, but require a uniform tag ID distribution. This means they are very dependent of the distribution of the IDs of the tags. Tag IDs are written in the tag and contain a predefined bit string of data. A study of the influence of the tag ID distribution on the protocols’ behaviour is proposed here. A new protocol, called the Flexible Query window Tree (FQwT) is presented to estimate the tag ID distribution, taking into consideration the type of distribution. The aim is to create a flexible anti-collision protocol in order to identify a set of tags that constitute an ID distribution. As a result, the reader classifies tags into groups determined by using a distribution estimator. Simulations show that the FQwT protocol contributes to significant reductions in identification time and energy consumption regardless of the type of ID distribution. PMID:28817070

Influence of the Distribution of Tag IDs on RFID Memoryless Anti-Collision Protocols.

PubMed

Cmiljanic, Nikola; Landaluce, Hugo; Perallos, Asier; Arjona, Laura

2017-08-17

In recent years, Radio Frequency Identification (RFID) has become very popular. The main feature of this technology is that RFID tags do not require close handling and no line of sight is required between the reader and the tags. RFID is a technology that uses radio frequencies in order to identify tags, which do not need to be positioned accurately relative to the reader. Tags share the communication channel, increasing the likelihood of causing a problem, viz., a message collision. Tree based protocols can resolve these collisions, but require a uniform tag ID distribution. This means they are very dependent of the distribution of the IDs of the tags. Tag IDs are written in the tag and contain a predefined bit string of data. A study of the influence of the tag ID distribution on the protocols' behaviour is proposed here. A new protocol, called the Flexible Query window Tree (FQwT) is presented to estimate the tag ID distribution, taking into consideration the type of distribution. The aim is to create a flexible anti-collision protocol in order to identify a set of tags that constitute an ID distribution. As a result, the reader classifies tags into groups determined by using a distribution estimator. Simulations show that the FQwT protocol contributes to significant reductions in identification time and energy consumption regardless of the type of ID distribution.

Electromagnetic dip and hump solitary structures in oxygen-hydrogen dissipative plasmas

NASA Astrophysics Data System (ADS)

Hussain, S.; Haseeb, Mahnaz Q.; Hasnain, H.

2017-10-01

The excitation of low frequency magnetosonic waves in O + - H + - e - and O + - H - - e - collisional plasmas is studied. The light ions (hydrogen) may be positive as well as negative and are warm, and the heavy ions (oxygen) are considered as the cold species. The inertia of isothermal electrons is also considered. The collisions of ions and electrons with neutrals are taken into account. The hydrodynamic equations represent the dynamics of positive ions, negative ions, and isothermal electrons along with Maxwell's equations. The damped Korteweg de Vries equation is derived by employing the reductive perturbation technique and its time dependent solution is presented. Dip magnetosonic solitary structures are observed when both ions are positive and hump structures are seen in the presence of negative ions. The effects of variations of different plasma parameters on magnetosonic solitary structures in the presence of collisions are discussed.

Non-linear effects of the built environment on automobile-involved pedestrian crash frequency: A machine learning approach.

PubMed

Ding, Chuan; Chen, Peng; Jiao, Junfeng

2018-03-01

Although a growing body of literature focuses on the relationship between the built environment and pedestrian crashes, limited evidence is provided about the relative importance of many built environment attributes by accounting for their mutual interaction effects and their non-linear effects on automobile-involved pedestrian crashes. This study adopts the approach of Multiple Additive Poisson Regression Trees (MAPRT) to fill such gaps using pedestrian collision data collected from Seattle, Washington. Traffic analysis zones are chosen as the analytical unit. The effects of various factors on pedestrian crash frequency investigated include characteristics the of road network, street elements, land use patterns, and traffic demand. Density and the degree of mixed land use have major effects on pedestrian crash frequency, accounting for approximately 66% of the effects in total. More importantly, some factors show clear non-linear relationships with pedestrian crash frequency, challenging the linearity assumption commonly used in existing studies which employ statistical models. With various accurately identified non-linear relationships between the built environment and pedestrian crashes, this study suggests local agencies to adopt geo-spatial differentiated policies to establish a safe walking environment. These findings, especially the effective ranges of the built environment, provide evidence to support for transport and land use planning, policy recommendations, and road safety programs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electric Field Strength Of Coherent Radio Emission In Rock Salt Concerning Ultra High-Energy Neutrino Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Y.; Chiba, M.; Yasuda, O.

2006-07-12

Detection possibility of ultra high-energy (UHE) neutrino (E >1015 eV) in natural huge rock salt formation has been studied. Collision between the UHE neutrino and the rock salt produces electromagnetic (EM) shower. Charge difference (excess electrons) between electrons and positrons in EM shower radiates radio wave coherently (Askar'yan effect). Angular distribution and frequency spectrum of electric field strength of radio wave radiated from 3-dimensional EM shower in rock salt are presented.

A model of fast radio bursts: collisions between episodic magnetic blobs

NASA Astrophysics Data System (ADS)

Li, Long-Biao; Huang, Yong-Feng; Geng, Jin-Jun; Li, Bing

2018-06-01

Fast radio bursts (FRBs) are bright radio pulses from the sky with millisecond durations and Jansky-level flux densities. Their origins are still largely uncertain. Here we suggest a new model for FRBs. We argue that the collision of a white dwarf with a black hole can generate a transient accretion disk, from which powerful episodicmagnetic blobs will be launched. The collision between two consecutive magnetic blobs can result in a catastrophic magnetic reconnection, which releases a large amount of free magnetic energy and forms a forward shock. The shock propagates through the cold magnetized plasma within the blob in the collision region, radiating through the synchrotron maser mechanism, which is responsible for a non-repeating FRB signal. Our calculations show that the theoretical energetics, radiation frequency, duration timescale and event rate can be very consistent with the observational characteristics of FRBs.

Accurate deuterium spectroscopy for fundamental studies

NASA Astrophysics Data System (ADS)

Wcisło, P.; Thibault, F.; Zaborowski, M.; Wójtewicz, S.; Cygan, A.; Kowzan, G.; Masłowski, P.; Komasa, J.; Puchalski, M.; Pachucki, K.; Ciuryło, R.; Lisak, D.

2018-07-01

We present an accurate measurement of the weak quadrupole S(2) 2-0 line in self-perturbed D2 and theoretical ab initio calculations of both collisional line-shape effects and energy of this rovibrational transition. The spectra were collected at the 247-984 Torr pressure range with a frequency-stabilized cavity ring-down spectrometer linked to an optical frequency comb (OFC) referenced to a primary time standard. Our line-shape modeling employed quantum calculations of molecular scattering (the pressure broadening and shift and their speed dependencies were calculated, while the complex frequency of optical velocity-changing collisions was fitted to experimental spectra). The velocity-changing collisions are handled with the hard-sphere collisional kernel. The experimental and theoretical pressure broadening and shift are consistent within 5% and 27%, respectively (the discrepancy for shift is 8% when referred not to the speed averaged value, which is close to zero, but to the range of variability of the speed-dependent shift). We use our high pressure measurement to determine the energy, ν0, of the S(2) 2-0 transition. The ab initio line-shape calculations allowed us to mitigate the expected collisional systematics reaching the 410 kHz accuracy of ν0. We report theoretical determination of ν0 taking into account relativistic and QED corrections up to α5. Our estimation of the accuracy of the theoretical ν0 is 1.3 MHz. We observe 3.4σ discrepancy between experimental and theoretical ν0.

Tailored-waveform Collisional Activation of Peptide Ion Electron Transfer Survivor Ions in Cation Transmission Mode Ion/Ion Reaction Experiments

PubMed Central

Han, Hongling; Londry, Frank A.; Erickson, David E.; McLuckey, Scott A.

2010-01-01

SUMMARY Broad-band resonance excitation via a tailored waveform in a high pressure collision cell (Q2) on a hybrid quadrupole/time-of-flight (QqTOF) tandem mass spectrometer has been implemented for cation transmission mode electron transfer ion/ion reactions of tryptic polypeptides. The frequency components in the broadband waveform were defined to excite the first generation intact electron transfer products for relatively large tryptic peptides. The optimum amplitude of the arbitrary waveform applied has been determined empirically to be 3.0 Vp-p, which is effective for relatively high mass-to-charge (m/z) ratio precursor ions with little elimination of sequence information for low m/z ions. The application of broadband activation during the transmission mode ion/ion reaction obviates frequency and amplitude tuning normally associated with ion trap collision induced dissociation (CID). This approach has been demonstrated with triply and doubly charged tryptic peptides with and without post-translational modifications. Enhanced structural information was achieved by production of a larger number of informative c- and z-type fragments using the tailored waveform on unmodified and modified (phosphorylated and glycosylated) peptides when the first generation intact electron transfer products fell into the defined frequency range. This approach can be applied to a wide range of tryptic peptide ions, making it attractive as a rapid and general approach for ETD LC-MS/MS of tryptic peptides in a QqTOF instrument. PMID:19305916

Visually guided locomotion and computation of time-to-collision in the mongolian gerbil (Meriones unguiculatus): the effects of frontal and visual cortical lesions.

PubMed

Shankar, S; Ellard, C

2000-02-01

Past research has indicated that many species use the time-to-collision variable but little is known about its neural underpinnings in rodents. In a set of three experiments we set out to replicate and extend the findings of Sun et al. (Sun H-J, Carey DP, Goodale MA. Exp Brain Res 1992;91:171-175) in a visually guided task in Mongolian gerbils, and then investigated the effects of lesions to different cortical areas. We trained Mongolian gerbils to run in the dark toward a target on a computer screen. In some trials the target changed in size as the animal ran toward it in such a way as to produce 'virtual targets' if the animals were using time-to-collision or contact information. In experiment 1 we confirmed that gerbils use time-to-contact information to modulate their speed of running toward a target. In experiment 2 we established that visual cortex lesions attenuate the ability of lesioned animals to use information from the visual target to guide their run, while frontal cortex lesioned animals are not as severely affected. In experiment 3 we found that small radio-frequency lesions, of either area VI or of the lateral extrastriate regions of the visual cortex also affected the use of information from the target to modulate locomotion.

Safety diagnosis: are we doing a good job?

PubMed

Park, Peter Y; Sahaji, Rajib

2013-03-01

Collision diagnosis is the second step in the six-step road safety management process described in the AASHTO Highway Safety Manual (HSM). Diagnosis is designed to identify a dominant or abnormally high proportion of particular collision configurations (e.g., rear end, right angle, etc.) at a target location. The primary diagnosis method suggested in the HSM is descriptive data analysis. This type of analysis relies on, for example, pie charts, histograms, and/or collision diagrams. Using location specific collision data (e.g., collision frequency per collision configuration for a target location), safety engineers identify (the most) frequent collision configurations. Safety countermeasures are then likely to concentrate on preventing the selected collision configurations. Although its real-world application in engineering practice is limited, an additional collision diagnosis method, known as the beta-binomial (BB) test, is also presented as the secondary diagnosis tool in the HSM. The BB test compares the proportion of a particular collision configuration observed at one location with the proportion of the same collision configuration found at other reference locations which are similar to the target location in terms of selected traffic and roadway characteristics (e.g., traffic volume, traffic control, and number of lanes). This study compared the outcomes obtained from descriptive data analysis and the BB test, and investigates two questions: (1) Do descriptive data analysis and the BB tests produce the same results (i.e., do they select the same collision configurations at the same locations)? and (2) If the tests produce different results, which result should be adopted in engineering practice? This study's analysis was based on a sample of the most recent five years (2005-2009) of collision and roadway configuration data for 143 signalized intersections in the City of Saskatoon, Saskatchewan. The study results show that the BB test's role in diagnosing safety concerns in road safety engineering projects such as safety review projects for existing roadways may be just as important as the descriptive data analysis method. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of convection electric field on upwelling and escape of ionospheric O(+)

NASA Technical Reports Server (NTRS)

Cladis, J. B.; Chiu, Yam T.; Peterson, William K.

1992-01-01

A Monte Carlo code is used to explore the full effects of the convection electric field on distributions of upflowing O(+) ions from the cusp/cleft ionosphere. Trajectories of individual ions/neutrals are computed as they undergo multiple charge-exchange collisions. In the ion state, the trajectories are computed in realistic models of the magnetic field and the convection, corotation, and ambipolar electric fields. The effects of ion-ion collisions are included, and the trajectories are computed with and without simultaneous stochastic heating perpendicular to the magnetic field by a realistic model of broadband, low frequency waves. In the neutral state, ballistic trajectories in the gravitational field are computed. The initial conditions of the ions, in addition to ambipolar electric field and the number densities and temperatures of O(+), H(+), and electrons as a function of height in the cusp/cleft region were obtained from the results of Gombosi and Killeen (1987), who used a hydrodynamic code to simulate the time-dependent frictional-heating effects in a magnetic tube during its motion though the convection throat. The distribution of the ion fluxes as a function of height are constructed from the case histories.

Finite-Frequency Seismic Imaging of Upper-Mantle Velocity Structures Beneath the South China Continent

NASA Astrophysics Data System (ADS)

Qu, P.; Chen, Y. J.; Yu, Y.

2017-12-01

South China Continent is major formed from the Paleo-South China plate. The continent has experienced complicated tectonic history after Neoproterozoic. Previous studies suggested some possible model for the collision between South China Continent and North China Continent. Body wave tomography and surface wave tomography are widely used to inverse upper mantle velocity structure. In our study, finite frequency tomography were carried on to get explanation more correctly. We gathered nearly 60000 pieces of teleseismic event records by 166 broad band seismic stations with Mw > 5.5. Here sensitive kernel of ak135 velocity structure was calculated, which is based on Born approximation, and then we applied multi-channel cross-correlation to pick arrival time difference under 3 frequency band. Combining with crust thickness correct from receiver function, we solve the inversion matrix by LSQR method, and get accurate upper mantle structure of P, S velocity. For more accurate results, we apply a method to calculate Vp/Vs ratio, to help to verify the velocity anomaly. The result in this research shows: 1. A strong velocity anomaly exists in the northern of South China Continent, in an area 31°N between 112°-118°E. The anomaly is about . We suggest that, this anomaly is related to the collision from North China Continent. It implies the collision underthrusted to southward. 2. A clearly slow velocity anomaly exists in the northern of Cathaysia block. This low velocity anomaly exist on the boundary of Yangtz block and Cathysian block, it is related to the left over of block collision in early phanerozoic. 3. We recognized some little velocity anomaly exit in the research area. Comparing these velocity anomaly with U-Pb zircon ages, we suggest complicated orogenesis in Phanerozoic is the cause of the formation of these little anomaly. The result in our study support the collision model, which shows the underthrust direction is southward, on the south of Qinling-Dabie Orogen. The anomaly mass is larger than the composite orogenic in Yangtze block.

Do school crossing guards make crossing roads safer? A quasi-experimental study of pedestrian-motor vehicle collisions in Toronto, Canada.

PubMed

Rothman, Linda; Perry, Daniel; Buliung, Ron; Macarthur, Colin; To, Teresa; Macpherson, Alison; Larsen, Kristian; Howard, Andrew

2015-07-31

The presence of school crossing guards has been associated with more walking and more pedestrian-motor vehicle collisions (PMVCs) in area-level cross-sectional analyses. The objectives of the study were to (1) Determine the effect on PMVC rates of newly implemented crossing guards in Toronto, Canada (2) Determine where collisions were located in relation to crossing guards throughout the city, and whether they occurred during school travel times. School crossing guards with 50 m buffers were mapped along with police-reported child PMVCs from 2000-2011. (1) A quasi-experimental study identified all age collision counts near newly implemented guards before and after implementation, modeled using repeated measures Poisson regression adjusted for season and built environment variables. (2) A retrospective cohort study of all child PMVCS throughout the city to determine the proportions of child PMVCs which occurred during school travel times and at guard locations. There were 27,827 PMVCs, with 260 PMVCs at the locations of 58 newly implemented guards. Repeated measures adjusted Poisson regression found PMVCs rates remained unchanged at guard locations after implementation (IRR 1.02, 95 % CI 0.74, 1.39). There were 568 guards citywide with 1850 child PMVCs that occurred at guard locations. The majority of child PMVCs occurred outside school travel times (n = 1155, 62 %) and of those that occurred during school travel times, only 95 (13.7 %) were at a guard location. School crossing guards are a simple roadway modification to increase walking to school without apparent detrimental safety effects. Other more permanent interventions are necessary to address the frequency of child PMVCs occurring away from the location of crossing guards, and outside of school travel times.

An Analysis of Information Assurance Relating to the Department of Defense Radio Frequency Identification (RFID) Passive Network

DTIC Science & Technology

2005-03-01

codes speed up consumer shopping, package shipping, and inventory tracking. RFID offers many advantages over bar codes, as the table below shows...sunlight” (Accenture, 2001, p. 4). Finally, one of the most significant advantages of RFID is the advent of anti-collision. Anti-collision allows an...RFID reader to read and/or write to multiple tags at one time, which is not possible for bar codes. Despite the many advantages RFID over bar codes

Development of Fast Deterministic Physically Accurate Solvers for Kinetic Collision Integral for Applications of Near Space Flight and Control Devices

DTIC Science & Technology

2015-08-31

following functions were used: where are the Legendre polynomials of degree . It is assumed that the coefficient standing with has the form...enforce relaxation rates of high order moments, higher order polynomial basis functions are used. The use of high order polynomials results in strong...enforced while only polynomials up to second degree were used in the representation of the collision frequency. It can be seen that the new model

Solution of non-continuum flows using BGK-type model with enforced relaxation of moments

NASA Astrophysics Data System (ADS)

Alekseenko, Alexander; Gimelshein, Sergey; Nguyen, Truong; Vedula, Prakash

2016-11-01

A BGK-type model with velocity dependent collision frequency and enforced relaxation rates for selected moments is applied to simulation of one- and two-dimensional super sonic flows. Relaxation rates of the moments are estimated by evaluating the full Boltzmann collision integral several times during the simulation. The solutions show improvements in velocity and temperature profiles as compared to the classical ES-BGK model. However, enforcement of relaxation rates for high order moments increases stiffness of the model.

- and Frequency-Domain Signatures of Velocity Changing Collisions in Sub-Doppler Saturation Spectra and Pressure Broadening

NASA Astrophysics Data System (ADS)

Hall, Gregory; Xu, Hong; Forthomme, Damien; Dagdigian, Paul; Sears, Trevor

2017-06-01

We have combined experimental and theoretical approaches to the competition between elastic and inelastic collisions of CN radicals with Ar, and how this competition influences time-resolved saturation spectra. Experimentally, we have measured transient, two-color sub-Doppler saturation spectra of CN radicals with an amplitude chopped saturation laser tuned to selected Doppler offsets within rotational lines of the A-X (2-0) band, while scanning a frequency modulated probe laser across the hyperfine-resolved saturation features of corresponding rotational lines of the A-X (1-0) band. A steady-state depletion spectrum includes off-resonant contributions ascribed to velocity diffusion, and the saturation recovery rates depend on the sub-Doppler detuning. The experimental results are compared with Monte Carlo solutions to the Boltzmann equation for the collisional evolution of the velocity distributions of CN radicals, combined with a pressure-dependent and speed-dependent lifetime broadening. Velocity changing collisions are included by appropriately sampling the energy resolved differential cross sections for elastic scattering of selected rotational states of CN (X). The velocity space diffusion of Doppler tagged molecules proceeds through a series of small-angle scattering events, eventually terminating in an inelastic collision that removes the molecule from the coherently driven ensemble of interest. Collision energy-dependent total cross sections and differential cross sections for elastic scattering of selected CN rotational states with Ar were computed with Hibridon quantum scattering calculations, and used for sampling in the Monte Carlo modeling. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-SC0012704 with the U.S. Department of Energy, Office of Science, and supported by its Division of Chemical Sciences, Geosciences and Biosciences within the Office of Basic Energy Sciences.

Particle behavior simulation in thermophoresis phenomena by direct simulation Monte Carlo method

NASA Astrophysics Data System (ADS)

Wada, Takao

2014-07-01

A particle motion considering thermophoretic force is simulated by using direct simulation Monte Carlo (DSMC) method. Thermophoresis phenomena, which occur for a particle size of 1 μm, are treated in this paper. The problem of thermophoresis simulation is computation time which is proportional to the collision frequency. Note that the time step interval becomes much small for the simulation considering the motion of large size particle. Thermophoretic forces calculated by DSMC method were reported, but the particle motion was not computed because of the small time step interval. In this paper, the molecule-particle collision model, which computes the collision between a particle and multi molecules in a collision event, is considered. The momentum transfer to the particle is computed with a collision weight factor, where the collision weight factor means the number of molecules colliding with a particle in a collision event. The large time step interval is adopted by considering the collision weight factor. Furthermore, the large time step interval is about million times longer than the conventional time step interval of the DSMC method when a particle size is 1 μm. Therefore, the computation time becomes about one-millionth. We simulate the graphite particle motion considering thermophoretic force by DSMC-Neutrals (Particle-PLUS neutral module) with above the collision weight factor, where DSMC-Neutrals is commercial software adopting DSMC method. The size and the shape of the particle are 1 μm and a sphere, respectively. The particle-particle collision is ignored. We compute the thermophoretic forces in Ar and H2 gases of a pressure range from 0.1 to 100 mTorr. The results agree well with Gallis' analytical results. Note that Gallis' analytical result for continuum limit is the same as Waldmann's result.

The Effect of the Spin-Forbidden Co((sup 1) Sigma plus) plus O((sup 3) P) Yields CO2 (1 Sigma (sub G) plus) Recombination Reaction on Afterbody Heating of Mars Entry Vehicles

NASA Technical Reports Server (NTRS)

Xu, Lu T.; Jaffe, Richard L.; Schwenke, David W.; Panesi, Marco

2017-01-01

Vibrationally excited CO2, formed by two-body recombination from CO((sup 1) sigma plus) and O((sup 3) P) in the wake behind spacecraft entering the Martian atmosphere reaction, is potentially responsible for the higher than anticipated radiative heating of the backshell, compared to pre-flight predictions. This process involves a spin-forbidden transition of the transient triplet CO2 molecule to the longer-lived singlet. To accurately predict the singlet-triplet transition probability and estimate the thermal rate coefficient of the recombination reaction, ab initio methods were used to compute the first singlet and three lowest triplet CO2 potential energy surfaces and the spin-orbit coupling matrix elements between these states. Analytical fits to these four potential energy surfaces were generated for surface hopping trajectory calculations, using Tully's fewest switches surface hopping algorithm. Preliminary results for the trajectory calculations are presented. The calculated probability of a CO((sup 1) sigma plus) and O((sup 3) P) collision leading to singlet CO2 formation is on the order of 10 (sup -4). The predicted flowfield conditions for various Mars entry scenarios predict temperatures in the range of 1000 degrees Kelvin - 4000 degrees Kelvin and pressures in the range of 300-2500 pascals at the shoulder and in the wake, which is consistent with a heavy-particle collision frequency of 10 (sup 6) to 10 (sup 7) per second. Owing to this low collision frequency, it is likely that CO((sup 1) sigma plus) molecules formed by this mechanism will mostly be frozen in a highly nonequilibrium rovibrational energy state until they relax by photoemission.

Impact-based piezoelectric energy harvester for multidimensional, low-level, broadband, and low-frequency vibrations

NASA Astrophysics Data System (ADS)

Zhang, Hongjiang; Jiang, Senlin; He, Xuefeng

2017-05-01

This letter proposes an impact-based piezoelectric energy harvester that uses a rolling bead contained in a bracket that is supported by a spring. Under either translational or rotational base excitation, the bead moves within the bracket and collides with piezoelectric cantilevers that are located around the bracket; these collisions cause the piezoelectric beams to vibrate and thus produce electrical outputs. The low rolling friction and the motion amplification effect of the spring make the resulting device suitable for collection of low-level vibration energy. Experiments show that the proposed harvester is promising for use in scavenging of energy from the multidimensional, low-level, broadband, and low-frequency vibrations that occur in natural environments.

Improved momentum-transfer theory for ion mobility. 1. Derivation of the fundamental equation.

PubMed

Siems, William F; Viehland, Larry A; Hill, Herbert H

2012-11-20

For the first time the fundamental ion mobility equation is derived by a bottom-up procedure, with N real atomic ion-atomic neutral collisions replaced by N repetitions of an average collision. Ion drift velocity is identified as the average of all pre- and postcollision velocities in the field direction. To facilitate velocity averaging, collisions are sorted into classes that "cool" and "heat" the ion. Averaging over scattering angles establishes mass-dependent relationships between pre- and postcollision velocities for the cooling and heating classes, and a combined expression for drift velocity is obtained by weighted addition according to relative frequencies of the cooling and heating encounters. At zero field this expression becomes identical to the fundamental low-field ion mobility equation. The bottom-up derivation identifies the low-field drift velocity as 3/4 of the average precollision ion velocity in the field direction and associates the passage from low-field to high-field conditions with the increasing dominance of "cooling" collisions over "heating" collisions. Most significantly, the analysis provides a direct path for generalization to fields of arbitrary strength.

Collision Models for Particle Orbit Code on SSX

NASA Astrophysics Data System (ADS)

Fisher, M. W.; Dandurand, D.; Gray, T.; Brown, M. R.; Lukin, V. S.

2011-10-01

Coulomb collision models are being developed and incorporated into the Hamiltonian particle pushing code (PPC) for applications to the Swarthmore Spheromak eXperiment (SSX). A Monte Carlo model based on that of Takizuka and Abe [JCP 25, 205 (1977)] performs binary collisions between test particles and thermal plasma field particles randomly drawn from a stationary Maxwellian distribution. A field-based electrostatic fluctuation model scatters particles from a spatially uniform random distribution of positive and negative spherical potentials generated throughout the plasma volume. The number, radii, and amplitude of these potentials are chosen to mimic the correct particle diffusion statistics without the use of random particle draws or collision frequencies. An electromagnetic fluctuating field model will be presented, if available. These numerical collision models will be benchmarked against known analytical solutions, including beam diffusion rates and Spitzer resistivity, as well as each other. The resulting collisional particle orbit models will be used to simulate particle collection with electrostatic probes in the SSX wind tunnel, as well as particle confinement in typical SSX fields. This work has been supported by US DOE, NSF and ONR.

53rd Course Molecular Physics and Plasmas in Hypersonics 2

DTIC Science & Technology

2013-09-09

between CO2 symmetric and bending modes ( 11 ) proceeds fast due to the Fermi resonance between the frequencies of these modes and can be considered as...of local maximization of the collision frequency given by Eq. ( 11 ) allows a strong reduction of the computational cost and it is verified a...called arc-jets or DC-Plasmatron [25, 26]. PWTs using Inductively Coupled Plasma (ICP) torch, based on Radio - Frequency (RF) discharge, are so- called

Characteristics of Polarisation in the Ramsauer-Townsend Minima in Strongly Coupled Semiclassic Plasmas

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-10-01

The influence of quantum shielding on the Ramsauer-Townsend phenomena for the total electron-atom polarisation collision cross-section is investigated in partially ionised strongly coupled semiclassic plasmas. The result shows that the quantum shielding effect changes the position of the Ramsauer energy in partially ionised strongly coupled plasmas. It is also found that the quantum shielding effect enhances the total electron-atom collision cross-section when the collision energy is greater than the Ramsauer energy; however, it suppresses the collision cross-section when the collision energy is smaller than the Ramsauer energy. In addition, it is shown that the plasma screening effect significantly changes the position of the Ramsauer energy and the influence of plasma screening on the magnitude of the collision cross-section is more significant near the Ramsauer energy domain. The variations of the Ramsauer energy and the collision cross-section due to the quantum shielding effect are also discussed.

Safety effects of low-cost engineering measures. An observational study in a Portuguese multilane road.

PubMed

Vieira Gomes, Sandra; Cardoso, João Lourenço

2012-09-01

Single carriageway multilane roads are not, in general, a very safe type of road, mainly because of the high number of seriously injured victims in head-on collisions, when compared with dual carriageway multilane roads, with a median barrier. In this paper the results of a study on the effect of the application of several low cost engineering measures, aimed at road infrastructure correction and road safety improvement on a multilane road (EN6), are presented. The study was developed by the National Laboratory of Civil Engineering (LNEC) for the Portuguese Road Administration and involved a comparison of selected aspects of motorized traffic behaviour (traffic volumes and speeds) measured in several sections of EN6, as well as monitoring of road safety developments in the same road. The applied low cost engineering measures allowed a reduction of 10% in the expected annual number of personal injury accidents and a 70% decrease in the expected annual number of head-on collisions; the expected annual frequency of accidents involving killed and seriously injured persons was reduced by 26%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Radio-Frequency Emissions from Streamer Collisions: Implications for High-Energy Processes.

NASA Astrophysics Data System (ADS)

Luque, A.

2017-12-01

The production of energetic particles in a discharge corona is possibly linked to the collision of streamers of opposite polarities [Cooray et al. (2009), Kochkin et al. (2012), Østgaard et al. (2016)]. There is also experimental evidence linking it to radio-frequency emissions in the UHF frequency range (300 MHz-3 GHz) [Montanyà et al. (2015), Petersen and Beasley (2014)]. Here we investigate these two links by modeling the radio-frequency emissions emanating from an encounter between two counter-propagating streamers. Our numerical model combines self-consistently a conservative, high-order Finite-Volume scheme for electron transport with a Finite-Difference Time-Domain (FDTD) method for electromagnetic propagation. We also include the most relevant reactions for streamer propagation: impact ionization, dissociative attachment and photo-ionization. Our implementation benefits from massive parallelization by running on a General-Purpose Graphical Processing Unit (GPGPU). With this code we found that streamer encounters emit electromagnetic waves predominantly in the UHF range, supporting the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges. References Cooray, V., et al., J. Atm. Sol.-Terr. Phys., 71, 1890, doi:10.1016/j.jastp.2009.07.010 (2009). Kochkin, P. O., et al., J. Phys. D, 45, 425202, doi: 10.1088/0022-3727/45/42/425202 (2012). Montanyà, J., et al., J. Atm. Sol.-Terr. Phys., 136, 94, doi:10.1016/j.jastp.2015.06.009, (2015). Østgaard, N., et al., J. Geophys. Res. (Atmos.), 121, 2939, doi:10.1002/2015JD024394 (2016). Petersen, D., and W. Beasley, Atmospheric Research, 135, 314, doi:10.1016/j.atmosres.2013.02.006 (2014).

On a method computing transient wave propagation in ionospheric regions

NASA Technical Reports Server (NTRS)

Gray, K. G.; Bowhill, S. A.

1978-01-01

A consequence of an exoatmospheric nuclear burst is an electromagnetic pulse (EMP) radiated from it. In a region far enough away from the burst, where nonlinear effects can be ignored, the EMP can be represented by a large-amplitude narrow-time-width plane-wave pulse. If the ionosphere intervenes the origin and destination of the EMP, frequency dispersion can cause significant changes in the original pulse upon reception. A method of computing these dispersive effects of transient wave propagation is summarized. The method described is different from the standard transform techniques and provides physical insight into the transient wave process. The method, although exact, can be used in approximating the early-time transient response of an ionospheric region by a simple integration with only explicit knowledge of the electron density, electron collision frequency, and electron gyrofrequency required. As an illustration of the method, it is applied to a simple example and contrasted with the corresponding transform solution.

Theory of plasma contractors for electrodynamic tethered satellite systems

NASA Technical Reports Server (NTRS)

Parks, D. E.; Katz, I.

1986-01-01

Recent data from ground and space experiments indicate that plasma releases from an object dramatically reduce the sheath impedance between the object and the ambient plasma surrounding it. Available data is in qualitative accord with the theory developed to quantify the flow of current in the sheath. Electron transport in the theory is based on a fluid model of a collisionless plasma with an effective collision frequency comparable to frequencies of plasma oscillations. The theory leads to low effective impedances varying inversely with the square root of the injected plasma density. To support such a low impedance mode of operation using an argon plasma source for example requires that only one argon ion be injected for each thirty electrons extracted from the ambient plasma. The required plasma flow rates are quite low; to extract one ampere of electron current requires a mass flow rate of about one gram of argon per day.

Reducing road traffic injuries: effectiveness of speed cameras in an urban setting.

PubMed

Pérez, Katherine; Marí-Dell'Olmo, Marc; Tobias, Aurelio; Borrell, Carme

2007-09-01

We assessed the effectiveness of speed cameras on Barcelona's beltway in reducing the numbers of road collisions and injuries and the number of vehicles involved in collisions. We designed a time-series study with a comparison group to assess the effects of the speed cameras. The "intervention group" was the beltway, and the comparison group consisted of arterial roads on which no fixed speed cameras had been installed. The outcome measures were number of road collisions, number of people injured, and number of vehicles involved in collisions. We fit the data to Poisson regression models that were adjusted according to trends and seasonality. The relative risk (RR) of a road collision occurring on the beltway after (vs before) installation of speed cameras was 0.73 (95% confidence interval [CI]=0.63, 0.85). This protective effect was greater during weekend periods. No differences were observed for arterial roads (RR=0.99; 95% CI=0.90, 1.10). Attributable fraction estimates for the 2 years of the study intervention showed 364 collisions prevented, 507 fewer people injured, and 789 fewer vehicles involved in collisions. Speed cameras installed in an urban setting are effective in reducing the numbers of road collisions and, consequently, the numbers of injured people and vehicles involved in collisions.

Surface acoustic wave coding for orthogonal frequency coded devices

NASA Technical Reports Server (NTRS)

Malocha, Donald (Inventor); Kozlovski, Nikolai (Inventor)

2011-01-01

Methods and systems for coding SAW OFC devices to mitigate code collisions in a wireless multi-tag system. Each device producing plural stepped frequencies as an OFC signal with a chip offset delay to increase code diversity. A method for assigning a different OCF to each device includes using a matrix based on the number of OFCs needed and the number chips per code, populating each matrix cell with OFC chip, and assigning the codes from the matrix to the devices. The asynchronous passive multi-tag system includes plural surface acoustic wave devices each producing a different OFC signal having the same number of chips and including a chip offset time delay, an algorithm for assigning OFCs to each device, and a transceiver to transmit an interrogation signal and receive OFC signals in response with minimal code collisions during transmission.

Code-division multiple-access protocol for active RFID systems

NASA Astrophysics Data System (ADS)

Mazurek, Gustaw; Szabatin, Jerzy

2008-01-01

Most of the Radio Frequency Identification (RFID) systems operating in HF and UHF bands employ narrowband modulations (FSK or ASK) with Manchester coding. However, these simple transmission schemes are vulnerable to narrowband interference (NBI) generated by other radio systems working in the same frequency band, and also suffer from collision problem and need special anti-collision procedures. This becomes especially important when operating in a noisy, crowded industrial environment. In this paper we show the performance of RFID system with DS-CDMA transmission in comparison to a standard system with FSK modulation defined in ISO 18000-7. Our simulation results show that without any bandwidth expansion the immunity against NBI can be improved by 8 dB and the system capacity can be 7 times higher when using DS-CDMA transmission instead of FSK modulation with Manchester coding.

Effect of a Dusty Layer on Surface-Wave Produced Plasmas

NASA Astrophysics Data System (ADS)

Ostrikov, Kostyantyn; Yu, Ming; Xu, Shuyan

2000-10-01

The effect of near-sheath dusts on the RF power loss in a surface-wave sustained gas discharge is studied. The planar plasma is bounded by a dielectric and consists of an inhomogeneous near-wall transition layer (sheath), a dusty plasma layer, and the outer dust-free plasma. The discharge is maintained by high-frequency axially-symmetric surface waves. The surface-wave power loss from the most relevant dissipative mechanisms in typical discharge plasmas is analyzed. Our model allows one to consider the main effects of dust particles on surface-wave produced discharge plasmas. We demonstrate that the dusts released in the discharge can strongly modify the plasma conductivity and lead to a significant redistribution of the total charge. They affect the electron quasi-momenta, but do not absorb the energy transmitted to the plasma through elastic collisions, and therefore they remain cold at the room temperature. It is shown that the improvement of the efficiency of energy transfer from the wave source to the plasma can be achieved by selecting operation regimes when the efficiency of the power loss in the plasma through electron-neutral collisions is higher than that through electron-dust interactions.

Collision partner selection schemes in DSMC: From micro/nano flows to hypersonic flows

NASA Astrophysics Data System (ADS)

Roohi, Ehsan; Stefanov, Stefan

2016-10-01

The motivation of this review paper is to present a detailed summary of different collision models developed in the framework of the direct simulation Monte Carlo (DSMC) method. The emphasis is put on a newly developed collision model, i.e., the Simplified Bernoulli trial (SBT), which permits efficient low-memory simulation of rarefied gas flows. The paper starts with a brief review of the governing equations of the rarefied gas dynamics including Boltzmann and Kac master equations and reiterates that the linear Kac equation reduces to a non-linear Boltzmann equation under the assumption of molecular chaos. An introduction to the DSMC method is provided, and principles of collision algorithms in the DSMC are discussed. A distinction is made between those collision models that are based on classical kinetic theory (time counter, no time counter (NTC), and nearest neighbor (NN)) and the other class that could be derived mathematically from the Kac master equation (pseudo-Poisson process, ballot box, majorant frequency, null collision, Bernoulli trials scheme and its variants). To provide a deeper insight, the derivation of both collision models, either from the principles of the kinetic theory or the Kac master equation, is provided with sufficient details. Some discussions on the importance of subcells in the DSMC collision procedure are also provided and different types of subcells are presented. The paper then focuses on the simplified version of the Bernoulli trials algorithm (SBT) and presents a detailed summary of validation of the SBT family collision schemes (SBT on transient adaptive subcells: SBT-TAS, and intelligent SBT: ISBT) in a broad spectrum of rarefied gas-flow test cases, ranging from low speed, internal micro and nano flows to external hypersonic flow, emphasizing first the accuracy of these new collision models and second, demonstrating that the SBT family scheme, if compared to other conventional and recent collision models, requires smaller number of particles per cell to obtain sufficiently accurate solutions.

Probability Forecasting Using Monte Carlo Simulation

NASA Astrophysics Data System (ADS)

Duncan, M.; Frisbee, J.; Wysack, J.

2014-09-01

Space Situational Awareness (SSA) is defined as the knowledge and characterization of all aspects of space. SSA is now a fundamental and critical component of space operations. Increased dependence on our space assets has in turn lead to a greater need for accurate, near real-time knowledge of all space activities. With the growth of the orbital debris population, satellite operators are performing collision avoidance maneuvers more frequently. Frequent maneuver execution expends fuel and reduces the operational lifetime of the spacecraft. Thus the need for new, more sophisticated collision threat characterization methods must be implemented. The collision probability metric is used operationally to quantify the collision risk. The collision probability is typically calculated days into the future, so that high risk and potential high risk conjunction events are identified early enough to develop an appropriate course of action. As the time horizon to the conjunction event is reduced, the collision probability changes. A significant change in the collision probability will change the satellite mission stakeholder's course of action. So constructing a method for estimating how the collision probability will evolve improves operations by providing satellite operators with a new piece of information, namely an estimate or 'forecast' of how the risk will change as time to the event is reduced. Collision probability forecasting is a predictive process where the future risk of a conjunction event is estimated. The method utilizes a Monte Carlo simulation that produces a likelihood distribution for a given collision threshold. Using known state and state uncertainty information, the simulation generates a set possible trajectories for a given space object pair. Each new trajectory produces a unique event geometry at the time of close approach. Given state uncertainty information for both objects, a collision probability value can be computed for every trail. This yields a collision probability distribution given known, predicted uncertainty. This paper presents the details of the collision probability forecasting method. We examine various conjunction event scenarios and numerically demonstrate the utility of this approach in typical event scenarios. We explore the utility of a probability-based track scenario simulation that models expected tracking data frequency as the tasking levels are increased. The resulting orbital uncertainty is subsequently used in the forecasting algorithm.

Neural hijacking: action of high-frequency electrical stimulation on cortical circuits.

PubMed

Cheney, P D; Griffin, D M; Van Acker, G M

2013-10-01

Electrical stimulation of the brain was one of the first experimental methods applied to understanding brain organization and function and it continues as a highly useful method both in research and clinical applications. Intracortical microstimulation (ICMS) involves applying electrical stimuli through a microelectrode suitable for recording the action potentials of single neurons. ICMS can be categorized into single-pulse stimulation; high-frequency, short-duration stimulation; and high-frequency, long-duration stimulation. For clinical and experimental reasons, considerable interest focuses on the mechanism of neural activation by electrical stimuli. In this article, we discuss recent results suggesting that action potentials evoked in cortical neurons by high-frequency electrical stimulation do not sum with the natural, behaviorally related background activity; rather, high-frequency stimulation eliminates and replaces natural activity. We refer to this as neural hijacking. We propose that a major component of the mechanism underlying neural hijacking is excitation of axons by ICMS and elimination of natural spikes by antidromic collision with stimulus-driven spikes evoked at high frequency. Evidence also supports neural hijacking as an important mechanism underlying the action of deep brain stimulation in the subthalamic nucleus and its therapeutic effect in treating Parkinson's disease.

Enhanced TDMA Based Anti-Collision Algorithm with a Dynamic Frame Size Adjustment Strategy for Mobile RFID Readers

PubMed Central

Shin, Kwang Cheol; Park, Seung Bo; Jo, Geun Sik

2009-01-01

In the fields of production, manufacturing and supply chain management, Radio Frequency Identification (RFID) is regarded as one of the most important technologies. Nowadays, Mobile RFID, which is often installed in carts or forklift trucks, is increasingly being applied to the search for and checkout of items in warehouses, supermarkets, libraries and other industrial fields. In using Mobile RFID, since the readers are continuously moving, they can interfere with each other when they attempt to read the tags. In this study, we suggest a Time Division Multiple Access (TDMA) based anti-collision algorithm for Mobile RFID readers. Our algorithm automatically adjusts the frame size of each reader without using manual parameters by adopting the dynamic frame size adjustment strategy when collisions occur at a reader. Through experiments on a simulated environment for Mobile RFID readers, we show that the proposed method improves the number of successful transmissions by about 228% on average, compared with Colorwave, a representative TDMA based anti-collision algorithm. PMID:22399942

Enhanced TDMA Based Anti-Collision Algorithm with a Dynamic Frame Size Adjustment Strategy for Mobile RFID Readers.

PubMed

Shin, Kwang Cheol; Park, Seung Bo; Jo, Geun Sik

2009-01-01

In the fields of production, manufacturing and supply chain management, Radio Frequency Identification (RFID) is regarded as one of the most important technologies. Nowadays, Mobile RFID, which is often installed in carts or forklift trucks, is increasingly being applied to the search for and checkout of items in warehouses, supermarkets, libraries and other industrial fields. In using Mobile RFID, since the readers are continuously moving, they can interfere with each other when they attempt to read the tags. In this study, we suggest a Time Division Multiple Access (TDMA) based anti-collision algorithm for Mobile RFID readers. Our algorithm automatically adjusts the frame size of each reader without using manual parameters by adopting the dynamic frame size adjustment strategy when collisions occur at a reader. Through experiments on a simulated environment for Mobile RFID readers, we show that the proposed method improves the number of successful transmissions by about 228% on average, compared with Colorwave, a representative TDMA based anti-collision algorithm.

Extending birthday paradox theory to estimate the number of tags in RFID systems.

PubMed

Shakiba, Masoud; Singh, Mandeep Jit; Sundararajan, Elankovan; Zavvari, Azam; Islam, Mohammad Tariqul

2014-01-01

The main objective of Radio Frequency Identification systems is to provide fast identification for tagged objects. However, there is always a chance of collision, when tags transmit their data to the reader simultaneously. Collision is a time-consuming event that reduces the performance of RFID systems. Consequently, several anti-collision algorithms have been proposed in the literature. Dynamic Framed Slotted ALOHA (DFSA) is one of the most popular of these algorithms. DFSA dynamically modifies the frame size based on the number of tags. Since the real number of tags is unknown, it needs to be estimated. Therefore, an accurate tag estimation method has an important role in increasing the efficiency and overall performance of the tag identification process. In this paper, we propose a novel estimation technique for DFSA anti-collision algorithms that applies birthday paradox theory to estimate the number of tags accurately. The analytical discussion and simulation results prove that the proposed method increases the accuracy of tag estimation and, consequently, outperforms previous schemes.

Extending Birthday Paradox Theory to Estimate the Number of Tags in RFID Systems

PubMed Central

Shakiba, Masoud; Singh, Mandeep Jit; Sundararajan, Elankovan; Zavvari, Azam; Islam, Mohammad Tariqul

2014-01-01

The main objective of Radio Frequency Identification systems is to provide fast identification for tagged objects. However, there is always a chance of collision, when tags transmit their data to the reader simultaneously. Collision is a time-consuming event that reduces the performance of RFID systems. Consequently, several anti-collision algorithms have been proposed in the literature. Dynamic Framed Slotted ALOHA (DFSA) is one of the most popular of these algorithms. DFSA dynamically modifies the frame size based on the number of tags. Since the real number of tags is unknown, it needs to be estimated. Therefore, an accurate tag estimation method has an important role in increasing the efficiency and overall performance of the tag identification process. In this paper, we propose a novel estimation technique for DFSA anti-collision algorithms that applies birthday paradox theory to estimate the number of tags accurately. The analytical discussion and simulation results prove that the proposed method increases the accuracy of tag estimation and, consequently, outperforms previous schemes. PMID:24752285

Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

NASA Astrophysics Data System (ADS)

Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P. K.

2007-09-01

The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO2 dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of ∂ω/∂k<0 are identified as signatures of dust dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.

FDTD Simulation on Terahertz Waves Propagation Through a Dusty Plasma

NASA Astrophysics Data System (ADS)

Wang, Maoyan; Zhang, Meng; Li, Guiping; Jiang, Baojun; Zhang, Xiaochuan; Xu, Jun

2016-08-01

The frequency dependent permittivity for dusty plasmas is provided by introducing the charging response factor and charge relaxation rate of airborne particles. The field equations that describe the characteristics of Terahertz (THz) waves propagation in a dusty plasma sheath are derived and discretized on the basis of the auxiliary differential equation (ADE) in the finite difference time domain (FDTD) method. Compared with numerical solutions in reference, the accuracy for the ADE FDTD method is validated. The reflection property of the metal Aluminum interlayer of the sheath at THz frequencies is discussed. The effects of the thickness, effective collision frequency, airborne particle density, and charge relaxation rate of airborne particles on the electromagnetic properties of Terahertz waves through a dusty plasma slab are investigated. Finally, some potential applications for Terahertz waves in information and communication are analyzed. supported by National Natural Science Foundation of China (Nos. 41104097, 11504252, 61201007, 41304119), the Fundamental Research Funds for the Central Universities (Nos. ZYGX2015J039, ZYGX2015J041), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120185120012)

Highway-rail intersection crash taxonomy for connected vehicle safety research

DOT National Transportation Integrated Search

2015-05-01

This report characterizes the frequency, severity, and costs of highway-rail intersection (HRI) collisions, and the estimated potential reductions in these metrics resulting from the implementation of Connected Vehicle HRI safety applications. Multip...

T-2 in Coherent Optics: Collision, Dephasing Time, or Reciprocal Linewidth.

ERIC Educational Resources Information Center

Nettel, Stephen J.; Lempicki, Alexander

1979-01-01

Discusses how the frequency domain (line widths) and time domain (coherent optical transients) are related to the concept of transverse relaxation time in the study of high resolution optical spectroscopy. (HM)

Monte-Carlo Orbit/Full Wave Simulation of Fast Alfvén Wave (FW) Damping on Resonant Ions in Tokamaks

NASA Astrophysics Data System (ADS)

Choi, M.; Chan, V. S.; Tang, V.; Bonoli, P.; Pinsker, R. I.; Wright, J.

2005-09-01

To simulate the resonant interaction of fast Alfvén wave (FW) heating and Coulomb collisions on energetic ions, including finite orbit effects, a Monte-Carlo code ORBIT-RF has been coupled with a 2D full wave code TORIC4. ORBIT-RF solves Hamiltonian guiding center drift equations to follow trajectories of test ions in 2D axisymmetric numerical magnetic equilibrium under Coulomb collisions and ion cyclotron radio frequency quasi-linear heating. Monte-Carlo operators for pitch-angle scattering and drag calculate the changes of test ions in velocity and pitch angle due to Coulomb collisions. A rf-induced random walk model describing fast ion stochastic interaction with FW reproduces quasi-linear diffusion in velocity space. FW fields and its wave numbers from TORIC are passed on to ORBIT-RF to calculate perpendicular rf kicks of resonant ions valid for arbitrary cyclotron harmonics. ORBIT-RF coupled with TORIC using a single dominant toroidal and poloidal wave number has demonstrated consistency of simulations with recent DIII-D FW experimental results for interaction between injected neutral-beam ions and FW, including measured neutron enhancement and enhanced high energy tail. Comparison with C-Mod fundamental heating discharges also yielded reasonable agreement.

Influence of quantum diffraction and shielding on electron-ion collision in two-component semiclassical plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Woo-Pyo; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791

2015-01-15

The influence of quantum diffraction and shielding on the electron-ion collision process is investigated in two-component semiclassical plasmas. The eikonal method and micropotential taking into account the quantum diffraction and shielding are used to obtain the eikonal scattering phase shift and the eikonal collision cross section as functions of the collision energy, density parameter, Debye length, electron de Broglie wavelength, and the impact parameter. The result shows that the quantum diffraction and shielding effects suppress the eikonal scattering phase shift as well as the differential eikonal collision cross section, especially, in small-impact parameter regions. It is also shown that themore » quantum shielding effect on the eikonal collision cross section is more important in low-collision energies. In addition, it is found that the eikonal collision cross section increases with an increase in the density parameter. The variations of the eikonal cross section due to the quantum diffraction and shielding effects are also discussed.« less

Investigation of the performance characteristics of Doppler radar technique for aircraft collision hazard warning, phase 3

NASA Technical Reports Server (NTRS)

1972-01-01

System studies, equipment simulation, hardware development and flight tests which were conducted during the development of aircraft collision hazard warning system are discussed. The system uses a cooperative, continuous wave Doppler radar principle with pseudo-random frequency modulation. The report presents a description of the system operation and deals at length with the use of pseudo-random coding techniques. In addition, the use of mathematical modeling and computer simulation to determine the alarm statistics and system saturation characteristics in terminal area traffic of variable density is discussed.

The Effect of Intense Laser Radiation on Atomic Collisions

NASA Astrophysics Data System (ADS)

Young, Stephen Michael Radley

1991-02-01

Available from UMI in association with The British Library. Requires signed TDF. We have carried out theoretical and experimental studies into the effect of intense laser radiation on atomic collisions. The first experiment used neon. Excitation by electron impact in a gas discharge demanded a pressure of at least 0.075 Torr. Measurement of the intensity of 3^1S_0to 3^1P_1 fluorescence has been made for the case where high intensity ASE wings in the laser profile and background laser scatter are unimportant, with the laser tuned to resonance. The field intensity required to produce strong field fluorescence (exemplified by the Mollow triplet) was found to give rise to complications capable of screening the effects sought. Our theoretical model has suggested that at finite detunings, line-centre fluorescence will dominate Rayleigh scatter and omega_3 fluorescence. Our measurements provide information on the saturation of neon fluorescence but not of the variation of the intense field collision rate. Absorption of weak field 253.7 nm laser photons by ground state mercury atoms yielded a high 6 ^3P_1 population at a lower pressure of 0.02 Torr. The Mollow triplet has been observed in the self-broadened mercury system. Dressing of the upper transition (6^3P_1rightarrow 7^3S_1) by an intense laser close to 435.8 nm yielded the strong field signal. Polarisation studies were made possible by the 3-level mercury system (radiation trapping in a 2-level system would depolarise fluorescence) perturbed by argon. The studies yielded results that were explainable in terms of the selective population of Stark shifted dressed states by a detuned, weak probe field. Use has been made of the electric-dipole radiation selection rule m_{J}=0 rightarrow m_{J^' } = 0 unless J=J^' to devise a 'Stark shift collision switch'. The competition between collision and radiation induced transitions within the mercury atom has then been studied. The resonant, strong lambda 435.8 nm field was used in conjunction with the weak lambda 253.7 nm field detuned by 0 to 6 cm^ {-1}. Measurement of fluorescence intensity in two perpendicular planes of polarisation has revealed the dominant | e_1> to | e_2> excitation channel as a function of the Stark shift by way of the U.V. detuning. Competition between the channels was dependent on the generalised Rabi frequency. However, we could only monitor the relative strength of the channels and were thus unable to say that the Stark shift switched collisions off. (Abstract shortened by UMI.).

Superdiffusion revisited in view of collisionless reconnection

NASA Astrophysics Data System (ADS)

Treumann, R. A.; Baumjohann, W.

2014-06-01

The concept of diffusion in collisionless space plasmas like those near the magnetopause and in the geomagnetic tail during reconnection is reexamined making use of the division of particle orbits into waiting orbits and break-outs into ballistic motion lying at the bottom, for instance, of Lévy flights. The rms average displacement in this case increases with time, describing superdiffusion, though faster than classical, is still a weak process, being however strong enough to support fast reconnection. Referring to two kinds of numerical particle-in-cell simulations we determine the anomalous diffusion coefficient, the anomalous collision frequency on which the diffusion process is based, and construct a relation between the diffusion coefficients and the resistive scale. The anomalous collision frequency from electron pseudo-viscosity in reconnection turns out to be of the order of the lower-hybrid frequency with the latter providing a lower limit, thus making similar assumptions physically meaningful. Tentative though not completely justified use of the κ distribution yields κ ≈ 6 in the reconnection diffusion region and, for the anomalous diffusion coefficient, the order of several times Bohm diffusivity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansson, Karl Wahlberg; Johansen, Anders; Syed, Mohtashim Bukhari

Some scenarios for planetesimal formation go through a phase of collapse of gravitationally bound clouds of millimeter- to centimeter-size pebbles. Such clouds can form, for example, through the streaming instability in protoplanetary disks. We model the collapse process with a statistical model to obtain the internal structure of planetesimals with solid radii between 10 and 1000 km. During the collapse, pebbles collide, and depending on their relative speeds, collisions have different outcomes. A mixture of particle sizes inside a planetesimal leads to better packing capabilities and higher densities. In this paper we apply results from new laboratory experiments of dustmore » aggregate collisions (presented in a companion paper) to model collision outcomes. We find that the internal structure of a planetesimal is strongly dependent on both its mass and the applied fragmentation model. Low-mass planetesimals have no/few fragmenting pebble collisions in the collapse phase and end up as porous pebble piles. The number of fragmenting collisions increases with increasing cloud mass, resulting in wider particle size distributions and higher density. The collapse is nevertheless “cold” in the sense that collision speeds are damped by the high collision frequency. This ensures that a significant fraction of large pebbles survive the collapse in all but the most massive clouds. Our results are in broad agreement with the observed increase in density of Kuiper Belt objects with increasing size, as exemplified by the recent characterization of the highly porous comet 67P/Churyumov–Gerasimenko.« less

Medication and Driving-Appropriate Interventions.

PubMed

Hitosugi, Masahito

2017-01-01

Sudden illness while driving has been identified as a major cause of vehicle collisions, accounting for approximately 1 in 10 collisions. Because most drivers who experience sudden illnesses while driving do not perform avoidance maneuvers, the improvement of drivers' health is being promoted as a traffic safety strategy. Although stroke, heart disease, and epilepsy are common causes of sudden illness, common symptoms, such as abdominal cramps, vertigo, and syncope can also cause problems during driving. We found that regular referral to physicians was significantly less common among drivers who experienced health-related vehicle collisions or incidents. Inadequate control of chronic disease might lead to unusual symptoms and the onset of major attacks. Medications are prescribed to patients to relieve their symptoms and/or bring their diseases under control. However, pharmacists and doctors should ensure that patients are treated with appropriate medications to avoid drivers being distracted due to adverse reactions to medications. The author suggests that it is important to keep drivers in good health and administer appropriate medications if necessary. Both pharmacists and doctors should warn drivers that sudden illness or medication-associated distractions can cause vehicle collisions. Such interventions might contribute to reducing the frequency of sudden illness-related vehicle collisions.

Coalescence Effects on Neutron Production in High Energy Nucleus-Nucleus Collisions

DTIC Science & Technology

2001-08-01

25/Jun/2001 THESIS 1 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER COALESCENCE EFFECTS ON NEUTRON PRODUCTION IN HIGH- ENERGY NUCLEUS-NUCLEUS COLLISIONS 5b... Energy Nucleus-Nucleus Collisions." I have examined the final copy of this thesis for form and content and recommend that it be accepted in partial...School COALESCENCE EFFECTS ON NEUTRON PRODUCTION IN HIGH ENERGY NUCLEUS-NUCLEUS COLLISIONS A Thesis Presented for the Master of Science Degree The

Theoretical investigation of exchange and recombination reactions in O(3P)+NO(2Π) collisions

NASA Astrophysics Data System (ADS)

Ivanov, M. V.; Zhu, H.; Schinke, R.

2007-02-01

We present a detailed dynamical study of the kinetics of O(P3)+NO(Π2) collisions including O atom exchange reactions and the recombination of NO2. The classical trajectory calculations are performed on the lowest A'2 and A″2 potential energy surfaces, which were calculated by ab initio methods. The calculated room temperature exchange reaction rate coefficient, kex, is in very good agreement with the measured one. The high-pressure recombination rate coefficient, which is given by the formation rate coefficient and to a good approximation equals 2kex, overestimates the experimental data by merely 20%. The pressure dependence of the recombination rate, kr, is described within the strong-collision model by assigning a stabilization probability to each individual trajectory. The measured falloff curve is well reproduced over five orders of magnitude by a single parameter, i.e., the strong-collision stabilization frequency. The calculations also yield the correct temperature dependence, kr∝T-1.5, of the low-pressure recombination rate coefficient. The dependence of the rate coefficients on the oxygen isotopes are investigated by incorporating the difference of the zero-point energies between the reactant and product NO radicals, ΔZPE, into the potential energy surface. Similar isotope effects as for ozone are predicted for both the exchange reaction and the recombination. Finally, we estimate that the chaperon mechanism is not important for the recombination of NO2, which is in accord with the overall T-1.4 dependence of the measured recombination rate even in the low temperature range.

ALMA Images of the Host Cloud of the Intermediate-mass Black Hole Candidate CO‑0.40–0.22*: No Evidence for Cloud–Black Hole Interaction, but Evidence for a Cloud–Cloud Collision

NASA Astrophysics Data System (ADS)

Tanaka, Kunihiko

2018-06-01

This paper reports a reanalysis of archival ALMA data of the high velocity(-width) compact cloud CO‑0.40–0.22, which has recently been hypothesized to host an intermediate-mass black hole (IMBH). If beam-smearing effects, difference in beam sizes among frequency bands, and Doppler shift due to the motion of the Earth are considered accurately, none of the features reported as evidence for an IMBH in previous studies are confirmed in the reanalyzed ALMA images. Instead, through analysis of the position–velocity structure of the HCN J = 3–2 data cube, we have found kinematics typical of a cloud–cloud collision (CCC), namely, two distinct velocity components bridged by broad emission features with elevated temperatures and/or densities. One velocity component has a straight filamentary shape with approximately constant centroid velocities along its length but with a steep, V-shaped velocity gradient across its width. This contradicts the IMBH scenario but is consistent with a collision between two dissimilar-sized clouds. From a non-LTE analysis of the multitransition methanol lines, the volume density of the post-shock gas has been measured to be ≳106 cm‑3, indicating that the CCC shock can compress gas in a short timescale to densities typical of star-forming regions. Evidence for star formation has not been found, possibly because the cloud is in an early phase of CCC-triggered star formation or because the collision is nonproductive.

Effect of vehicular size on chain-reaction crash

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

2015-11-01

We present the dynamic model of the chain-reaction crash to take account of the vehicular size. Drivers brake according to taillights of the forward vehicle. We investigate the effect of the vehicular size on the chain-reaction crash (multiple-vehicle collision) in the traffic flow controlled by taillights. In the multiple-vehicle collision, the first crash induces more collisions. We investigate how the first collision induces the chain-reaction crash numerically. We derive, analytically, the transition points and the region maps for the chain-reaction crash in the traffic flow of vehicles with finite sizes. We clarify the effect of the vehicular size on the multiple-vehicle collision.

Effect of collision duration on the chaotic dynamics of a ball bouncing on a vertically vibrating plate

NASA Astrophysics Data System (ADS)

Jiang, Z. H.; Liang, Z. J.; Wu, A. C.; Zheng, R. H.

2018-03-01

Experiments have been performed to study the chaotic dynamics of a ball bouncing on a vertically vibrating plate. The velocity dependence of collision duration and coefficient of restitution is determined, and phase portraits of chaotic structures for the flight time and the relative collision velocities are obtained. Numerical calculations are carried out to examine the effects of velocity-dependent collision duration on the ball dynamics. It is revealed that when the collision is instantaneous, sticking solutions are always observed, whereas when the collision duration is taken into account, sticking solutions are destroyed and thereby chaos behaviors are induced.

Macroscopic descriptions of rarefied gases from the elimination of fast variables

NASA Astrophysics Data System (ADS)

Dellar, Paul J.

2007-10-01

The Boltzmann equation describing a dilute monatomic gas is equivalent to an infinite hierarchy of evolution equations for successive moments of the distribution function. The five moments giving the macroscopic mass, momentum, and energy densities are unaffected by collisions between atoms, while all other moments naturally evolve on a fast collisional time scale. We show that the macroscopic equations of Chen, Rao, and Spiegel [Phys. Lett. A 271, 87 (2000)], like the familiar Navier-Stokes-Fourier equations, emerge from using a systematic procedure to eliminate the higher moments, leaving closed evolution equations for the five moments unaffected by collisions. The two equation sets differ through their treatment of contributions from the temperature to the momentum and energy fluxes. Using moment equations offers a definitive treatment of the Prandtl number problem using model collision operators, greatly reduces the labor of deriving equations for different collision operators, and clarifies the role of solvability conditions applied to the distribution function. The original Chen-Rao-Spiegel approach offers greatly improved agreement with experiments for the phase speed of ultrasound, but when corrected to match the Navier-Stokes-Fourier equations at low frequencies, it then underestimates the phase speed at high frequencies. Our introduction of a translational temperature, as in the kinetic theory of polyatomic gases, motivates a distinction in the energy flux between advection of internal energy and the work done by the pressure. Exploiting this distinction yields macroscopic equations that offer further improvement in agreement with experimental data, and arise more naturally as an approximation to the infinite hierarchy of evolution equations for moments.

Investigation of the magnetic neutral line region with the frame of two-fluid equations: A possibility of anomalous resistivity inferred from MMS observations

NASA Astrophysics Data System (ADS)

Kobayashi, Y.; Kitamura, N.; Ieda, A.; Yoshizumi, M.; Imada, S.; Tsugawa, Y.; Burch, J. L.; Russell, C. T.; Moore, T. E.; Giles, B. L.; Paterson, W.; Torbert, R. B.; Ergun, R.; Saito, Y.; Yokota, S.; Machida, S.

2017-12-01

Magnetic reconnection is a basic physical process by which energy of magnetic field is converted into the kinetic energy of plasmas. In recent years, MMS missionconsisting of four spacecraft has been conducted aiming at elucidating the physical mechanism of merging themagnetic fields in the vicinity of the magnetic neutral linethat exists in the central part of the structure. In this paper, we examine the magnetic field frozen-in relation near the magnetic neutral line as well as the causal relationship between electron and ion dynamics in the frame of two fluid equations.Theoretically, it is shown that electrons are frozen-in to the magnetic fields while ion's frozen-in relation is broken in the ion dissipation region. However, when we examined the observational data around 1307 UT on October 16, 2015 when MMS spacecraft passed through the vicinity of the magnetic neutral line [Burch et al., Science 2016] , it was confirmed that the frozen-ion relation was not established for electrons in the ion dissipation region. In addition, we found that intense wave electric fields in this region. From the spectral analysis of the waves, it turned out that their characteristic frequencies are the lower-hybrid and electron cyclotron frequencies.In the framework of the two-fluid equation, we can evaluate the values of each term of the equations of motion for both ions and electrons except for the collision term from MMS spacecraft data. Therefore, it is possible to obtain collision terms for both species. Since magnetospheric plasma is basically collisionless, it is considered that the collision term is due to anomalous resistivity associated with the excited waves . On the other hand, in the two-fluid equation system, the two vectors corresponding to the collision terms of ions and electrons have the same absolute value. Because the force exerted between the two is the internal force, they should face in the opposite direction. However, the vectors corresponding to the collision terms obtained by using the actual data did not satisfy such a condition. One of the possible reasons is that the momentum carried by the waves cannot be neglected. After careful examination, we conclude that the effect of the anomalous resistivity in the ion dissipation region acts to some degree that cannot be ignored in the equation of motion of the two-fluid system.

Energy-Aware RFID Anti-Collision Protocol.

PubMed

Arjona, Laura; Simon, Hugo Landaluce; Ruiz, Asier Perallos

2018-06-11

The growing interest in mobile devices is transforming wireless identification technologies. Mobile and battery-powered Radio Frequency Identification (RFID) readers, such as hand readers and smart phones, are are becoming increasingly attractive. These RFID readers require energy-efficient anti-collision protocols to minimize the tag collisions and to expand the reader's battery life. Furthermore, there is an increasing interest in RFID sensor networks with a growing number of RFID sensor tags. Thus, RFID application developers must be mindful of tag anti-collision protocols. Energy-efficient protocols involve a low reader energy consumption per tag. This work presents a thorough study of the reader energy consumption per tag and analyzes the main factor that affects this metric: the frame size update strategy. Using the conclusion of this analysis, the anti-collision protocol Energy-Aware Slotted Aloha (EASA) is presented to decrease the energy consumption per tag. The frame size update strategy of EASA is configured to minimize the energy consumption per tag. As a result, EASA presents an energy-aware frame. The performance of the proposed protocol is evaluated and compared with several state of the art Aloha-based anti-collision protocols based on the current RFID standard. Simulation results show that EASA, with an average of 15 mJ consumed per tag identified, achieves a 6% average improvement in the energy consumption per tag in relation to the strategies of the comparison.

Traumatic fractures resulting from collisions in children and adolescents: A retrospective observational study.

PubMed

Wang, Hongwei; Liu, Huan; Zhang, Song; Li, Changqing; Zhou, Yue; Liu, Jun; Ou, Lan; Xiang, Liangbi

2018-05-01

To investigate the incidence and pattern of child and adolescent (≤18 years old) traumatic fractures (TFs) as a result of collisions.We retrospectively reviewed 270 child and adolescent patients (228 males and 42 females aged 12.8 ± 5.1 years old) with TFs as a result of collisions admitted to our university-affiliated hospitals from 2001 to 2010. The incidence and patterns were summarized with respect to different age groups, sex, etiology, and whether the patient presented with nerve injury.The most common etiologies were struck by object (105, 38.9%) and wounded by person (74, 27.4%). The most common fracture sites were upper limb fractures (126, 46.7%) and craniofacial fractures (82, 30.4%). A total of 65 (24.1%) patients suffered a nerve injury. The frequency of early and late complications/associated injuries was 35.6% (n = 96) and 8.5% (n = 23), respectively. The mean age (P = .001) and frequency of wounded by person (P = .038) was significantly larger in male than in female patients. The frequency of earthquake injury (P < .001) and lower limb fractures (P = .002) was significantly larger in females than in male patients. The frequency of upper limb fracture was significantly higher in the wounded by machine group (83.3%) than in the other groups (all P < .05). The frequency of lower limb fractures was significantly higher in the earthquake injury group (64.7%) than in the other groups (all P < .05). The frequency of craniofacial fracture was significantly higher in the wounded by person group (54.1%) than in the other groups (all P < .05). The emergency admission rate (P = .047), frequency of wounded by person (P < .001), craniofacial fracture (P < .001), and early complications/associated injuries (P < .001) were significantly larger in patients with nerve injury than in other patients.Struck by object and upper limb fractures were the most common etiology and site, respectively. Wounded by person and craniofacial fractures were risk factors for nerve injury. Therefore, we should pay more attention to patients wounded by person, presenting with craniofacial fracture, to find whether there is nerve injury.

Vehicle manoeuvers as surrogate safety measures: Extracting data from the gps-enabled smartphones of regular drivers.

PubMed

Stipancic, Joshua; Miranda-Moreno, Luis; Saunier, Nicolas

2018-06-01

Network screening is a key element in identifying and prioritizing hazardous sites for engineering treatment. Traditional screening methods have used observed crash frequency or severity ranking criteria and statistical modelling approaches, despite the fact that crash-based methods are reactive. Alternatively, surrogate safety measures (SSMs) have become popular, making use of new data sources including video and, more rarely, GPS data. The purpose of this study is to examine vehicle manoeuvres of braking and accelerating extracted from a large quantity of GPS data collected using the smartphones of regular drivers, and to explore their potential as SSMs through correlation with historical collision frequency and severity across different facility types. GPS travel data was collected in Quebec City, Canada in 2014. The sample for this study contained over 4000 drivers and 21,000 trips. Hard braking (HBEs) and accelerating events (HAEs) were extracted and compared to historical crash data using Spearman's correlation coefficient and pairwise Kolmogorov-Smirnov tests. Both manoeuvres were shown to be positively correlated with crash frequency at the link and intersection levels, though correlations were much stronger when considering intersections. Locations with more braking and accelerating also tend to have more collisions. Concerning severity, higher numbers of vehicle manoeuvres were also related to increased collision severity, though this relationship was not always statistically significant. The inclusion of severity testing, which is an independent dimension of safety, represents a substantial contribution to the existing literature. Future work will focus on developing a network screening model that incorporates these SSMs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Injury pattern in lethal motorbikes-pedestrian collisions, in the area of Barcelona, Spain.

PubMed

Rebollo-Soria, M Carmen; Arregui-Dalmases, Carlos; Sánchez-Molina, David; Velázquez-Ameijide, Juan; Galtés, Ignasi

2016-10-01

There are several studies about M1 type vehicle-pedestrian collision injury pattern, and based on them, there has been several changes in automobiles for pedestrian protection. However, the lack of sufficient studies about injury pattern in motorbikes-pedestrian collisions leads to a lack of optimization design of these vehicles. The objective of this research is to study the injury pattern of pedestrians involved in collisions with motorized two-wheeled vehicles. A retrospective descriptive study of pedestrian's deaths after collisions with motorcycles in an urban area, like Barcelona was performed. The cases were collected from the Forensic Pathology Service database of the Institute of Legal Medicine of Catalonia. The selected cases were categorized as pedestrian-motorcycle collision, between January 1st, 2005 and December 31st, 2014. Data were collected from the autopsy, medical, and police report. The collected information was then analyzed using Microsoft Excel statistical functions. Traumatic Brain Injury is the main cause of death in pedestrian hit by motorized two-wheeled vehicles (62.85%). The most frequent injury was the subarachnoid hemorrhage, in 71.4% of cases, followed by cerebral contusions and skull base fractures (65.7%). By contrast, pelvic fractures and tibia fractures only appeared in 28.6%. The study characterizes the injury pattern of pedestrians involved in a collision with motorized two-wheeled vehicles in an urban area, like Barcelona, which has been found to be different from other vehicle-pedestrian collisions, with a higher incidence of brain injuries and minor frequency of lower extremities fractures in pelvis, tibia and fibula. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Effect of frequency on the uniformity of symmetrical RF CCP discharges

NASA Astrophysics Data System (ADS)

Liu, Yue; Booth, Jean-Paul; Chabert, Pascal

2018-05-01

A 2D Cartesian electrostatic particle-in-cell/Monte Carlo collision (PIC/MCC) model presented previously (Liu et al 2018 Plasma Sources Sci. Technol. 27 025006) is used to investigate the effect of the driving frequency (over the range of 15–45 MHz) on the plasma uniformity in radio frequency (RF) capacitively coupled plasma (CCP) discharges in a geometrically symmetric reactor with a dielectric side wall in argon gas. The reactor size (12 cm electrode length, 2.5 cm gap) and driving frequency are sufficiently small that electromagnetic effects can be ignored. Previously, we showed (Liu et al 2018 Plasma Sources Sci. Technol. 27 025006) that for 15 MHz excitation, Ohmic heating of electrons by the electric field perpendicular to the electrodes is enhanced in a region in front of the dielectric side wall, leading to a maximum in electron density there. In this work we show that increasing the excitation frequency (at constant applied voltage amplitude) not only increases the overall electron heating and density but also causes a stronger, narrower peak in electron heating closer to the dielectric wall, improving the plasma uniformity along the electrodes. This heating peak comes both from enhanced perpendicular electron heating and from the appearance at high frequency of significant parallel heating. The latter is caused by the presence of a significant parallel-direction RF oscillating electric field in the corners. Whereas at the reactor center the sheaths oscillate perpendicularly to the electrodes, near the dielectric edge they move in and out of the corners and must be treated in two dimensions.

Ungulate Vehicle Collisions in a Peri-Urban Environment: Consequences of Transportation Infrastructures Planned Assuming the Absence of Ungulates

PubMed Central

Zuberogoitia, Iñigo; del Real, Javier; Torres, Juan José; Rodríguez, Luis; Alonso, María; Zabala, Jabi

2014-01-01

Ungulate vehicle collisions (UVC) provoke serious damage, including human casualties, and a large number of measures have been developed around the world to avoid collisions. We analyse the main factors involved in UVC in a road network built in the absence of ungulates, where mitigation structures to avoid UVC were not adequately considered. Ungulate population greatly increased during the last two decades and now Roe Deer and Wild Boars are widely distributed over the study area, but even after this increase, the road network was not adapted to avoid UVC. A total of 235 Roe Deer (RDVC) and 153 Wild Boar vehicle collisions (WBVC) were recorded between January 2008 and December 2011. We randomly selected 289 sample points (87 RDVC, 60 WBVC and 142 controls) separated by at least 500 metres from the next closest point and measured 19 variables that could potentially influence the vehicle collisions. We detected variations in the frequency of RDVC on a monthly basis, and WBVC was higher at weekends but no significant differences were detected on a monthly basis. UVC were more likely to occur at locations where sinuosity of the road, velocity, surface of shrub and deciduous forest area were greater, the presence of fences entered with positive relationship and distance to the nearest building was less. RDVC were more likely to occur at locations where timber forest area increased and distance to the nearest building decreased and WBVC was related to open fields cover and also to the presence of fences. Sinuosity and velocity entered in both cases as significant factors. Major roads, in which the traffic volume is greater and faster, caused more accidents with ungulates than secondary roads. Nowadays, the high frequency of ungulate road-kills deserves a new strategy in order to adapt infrastructure and adopt mitigation measures. PMID:25251376

Ungulate vehicle collisions in a peri-urban environment: consequences of transportation infrastructures planned assuming the absence of ungulates.

PubMed

Zuberogoitia, Iñigo; del Real, Javier; Torres, Juan José; Rodríguez, Luis; Alonso, María; Zabala, Jabi

2014-01-01

Ungulate vehicle collisions (UVC) provoke serious damage, including human casualties, and a large number of measures have been developed around the world to avoid collisions. We analyse the main factors involved in UVC in a road network built in the absence of ungulates, where mitigation structures to avoid UVC were not adequately considered. Ungulate population greatly increased during the last two decades and now Roe Deer and Wild Boars are widely distributed over the study area, but even after this increase, the road network was not adapted to avoid UVC. A total of 235 Roe Deer (RDVC) and 153 Wild Boar vehicle collisions (WBVC) were recorded between January 2008 and December 2011. We randomly selected 289 sample points (87 RDVC, 60 WBVC and 142 controls) separated by at least 500 metres from the next closest point and measured 19 variables that could potentially influence the vehicle collisions. We detected variations in the frequency of RDVC on a monthly basis, and WBVC was higher at weekends but no significant differences were detected on a monthly basis. UVC were more likely to occur at locations where sinuosity of the road, velocity, surface of shrub and deciduous forest area were greater, the presence of fences entered with positive relationship and distance to the nearest building was less. RDVC were more likely to occur at locations where timber forest area increased and distance to the nearest building decreased and WBVC was related to open fields cover and also to the presence of fences. Sinuosity and velocity entered in both cases as significant factors. Major roads, in which the traffic volume is greater and faster, caused more accidents with ungulates than secondary roads. Nowadays, the high frequency of ungulate road-kills deserves a new strategy in order to adapt infrastructure and adopt mitigation measures.

Control of Rotational Energy and Angular Momentum Orientation with an Optical Centrifuge

NASA Astrophysics Data System (ADS)

Ogden, Hannah M.; Murray, Matthew J.; Mullin, Amy S.

2017-04-01

We use an optical centrifuge to trap and spin molecules to an angular frequency of 30 THz with oriented angular momenta and extremely high rotational energy and then investigate their subsequent collision dynamics with transient high resolution IR spectroscopy. The optical centrifuge is formed by combining oppositely-chirped pulses of 800 nm light, and overlapping them spatially and temporally. Polarization-sensitive Doppler-broadened line profiles characterize the anisotropic kinetic energy release of the super rotor molecules, showing that they behave like molecular gyroscopes. Studies are reported for collisions of CO2 super rotors with CO2, He and Ar. These studies reveal how mass, velocity and rotational adiabaticity impact the angular momentum relaxation and reorientation. Quantum scattering calculations provide insight into the J-specific collision cross sections that control the relaxation. NSF-CHE 105 8721.

Decoherence and Collisional Frequency Shifts of Trapped Bosons and Fermions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibble, Kurt; LNE-SYRTE, Observatoire de Paris, 75014 Paris

2009-09-11

We perform exact calculations of collisional frequency shifts for several fermions or bosons using a singlet and triplet basis for pairs of particles. The 'factor of 2 controversy' for bosons becomes clear - the factor is always 2. Decoherence is described by singlet states and they are unaffected by spatially uniform clock fields. Spatial variations are critical, especially for fermions which were previously thought to be immune to collision shifts. The spatial variations lead to decoherence and a novel frequency shift that is not proportional to the partial density of internal states.

Ridge-trench collision in Archean and Post-Archean crustal growth: Evidence from southern Chile

NASA Technical Reports Server (NTRS)

Nelson, E. P.; Forsythe, R. D.

1988-01-01

The growth of continental crust at convergent plate margins involves both continuous and episodic processes. Ridge-trench collision is one episodic process that can cause significant magmatic and tectonic effects on convergent plate margins. Because the sites of ridge collision (ridge-trench triple junctions) generally migrate along convergent plate boundaries, the effects of ridge collision will be highly diachronous in Andean-type orogenic belts and may not be adequately recognized in the geologic record. The Chile margin triple junction (CMTJ, 46 deg S), where the actively spreading Chile rise is colliding with the sediment-filled Peru-Chile trench, is geometrically and kinematically the simplest modern example of ridge collision. The south Chile margin illustrates the importance of the ridge-collision tectonic setting in crustal evolution at convergent margins. Similarities between ridge-collision features in southern Chile and features of Archean greenstone belts raise the question of the importance of ridge collision in Archean crustal growth. Archean plate tectonic processes were probably different than today; these differences may have affected the nature and importance of ridge collision during Archean crustal growth. In conclusion, it is suggested that smaller plates, greater ridge length, and/or faster spreading all point to the likelihood that ridge collision played a greater role in crustal growth and development of the greenstone-granite terranes during the Archean. However, the effects of modern ridge collision, and the processes involved, are not well enough known to develop specific models for the Archean ridge collison.

Are There Frame-Distortion Contributions to Collision-Induced Absorption and Collision-Induced Light Scattering?

NASA Astrophysics Data System (ADS)

Hohm, Uwe

2007-12-01

Collision-induced spectroscopy, such as collision-induced absorption (CIA) and collision-induced light scattering (CILS), can give valuable information on permanent electric moments, polarizabilities and intermolecular-interaction potentials. In general the collision-induced spectra of the pure rare-gases and their binary mixtures are understood fairly well. However if at least one of the collision partners is a molecule then in some cases the spectra show features which can hardly be explained by current theories which deal with the case of undistorted molecules. Here we discuss the possibility of collision-induced frame distortion as an additional effect to be considered in collision-induced spectroscopy.

On the relativistic large-angle electron collision operator for runaway avalanches in plasmas

NASA Astrophysics Data System (ADS)

Embréus, O.; Stahl, A.; Fülöp, T.

2018-02-01

Large-angle Coulomb collisions lead to an avalanching generation of runaway electrons in a plasma. We present the first fully conservative large-angle collision operator, derived from the relativistic Boltzmann operator. The relation to previous models for large-angle collisions is investigated, and their validity assessed. We present a form of the generalized collision operator which is suitable for implementation in a numerical kinetic equation solver, and demonstrate the effect on the runaway-electron growth rate. Finally we consider the reverse avalanche effect, where runaways are slowed down by large-angle collisions, and show that the choice of operator is important if the electric field is close to the avalanche threshold.

Predicting crash frequency for multi-vehicle collision types using multivariate Poisson-lognormal spatial model: A comparative analysis.

PubMed

Hosseinpour, Mehdi; Sahebi, Sina; Zamzuri, Zamira Hasanah; Yahaya, Ahmad Shukri; Ismail, Noriszura

2018-06-01

According to crash configuration and pre-crash conditions, traffic crashes are classified into different collision types. Based on the literature, multi-vehicle crashes, such as head-on, rear-end, and angle crashes, are more frequent than single-vehicle crashes, and most often result in serious consequences. From a methodological point of view, the majority of prior studies focused on multivehicle collisions have employed univariate count models to estimate crash counts separately by collision type. However, univariate models fail to account for correlations which may exist between different collision types. Among others, multivariate Poisson lognormal (MVPLN) model with spatial correlation is a promising multivariate specification because it not only allows for unobserved heterogeneity (extra-Poisson variation) and dependencies between collision types, but also spatial correlation between adjacent sites. However, the MVPLN spatial model has rarely been applied in previous research for simultaneously modelling crash counts by collision type. Therefore, this study aims at utilizing a MVPLN spatial model to estimate crash counts for four different multi-vehicle collision types, including head-on, rear-end, angle, and sideswipe collisions. To investigate the performance of the MVPLN spatial model, a two-stage model and a univariate Poisson lognormal model (UNPLN) spatial model were also developed in this study. Detailed information on roadway characteristics, traffic volume, and crash history were collected on 407 homogeneous segments from Malaysian federal roads. The results indicate that the MVPLN spatial model outperforms the other comparing models in terms of goodness-of-fit measures. The results also show that the inclusion of spatial heterogeneity in the multivariate model significantly improves the model fit, as indicated by the Deviance Information Criterion (DIC). The correlation between crash types is high and positive, implying that the occurrence of a specific collision type is highly associated with the occurrence of other crash types on the same road segment. These results support the utilization of the MVPLN spatial model when predicting crash counts by collision manner. In terms of contributing factors, the results show that distinct crash types are attributed to different subsets of explanatory variables. Copyright © 2018 Elsevier Ltd. All rights reserved.

Application of RFID in the area of agricultural products quality traceability and tracking and the anti-collision algorithm

NASA Astrophysics Data System (ADS)

Wang, Zu-liang; Zhang, Ting; Xie, Shi-yang

2017-01-01

In order to improve the agricultural tracing efficiency and reduce tracking and monitoring cost, agricultural products quality tracking and tracing based on Radio-Frequency Identification(RFID) technology is studied, then tracing and tracking model is set up. Three-layer structure model is established to realize the high quality of agricultural products traceability and tracking. To solve the collision problems between multiple RFID tags and improve the identification efficiency a new reservation slot allocation mechanism is proposed. And then we analyze and optimize the parameter by numerical simulation method.

Occupant injury protection in automobile collisions.

PubMed

Peters, G A; Peters, B J

1999-12-01

Modern technology has produced automotive vehicles that have become both a luxury and a necessity in modern civilization. They have become highly useful, even more varied in form and function, and capable of high speeds on crowded roadways. One unfortunate consequence is the high frequency of accidents and the greater severity of injuries when collisions do occur. In response, modern technology has produced a variety of safety and health features, devices and designs intended for better occupant protection on in high speed vehicles. Injury reduction has become a prime design objective, but there are residual risks, which, as technology evolves, require effective communication to those risk. There can be little risk avoidance behavior without awareness of the hazards and effective communication to the vehicle occupant, as to what could and should be done for self-protection. For example, one out of three drivers apparently fails to understand the function of head restraints, few understand the 'safe zone' posture required for air bags and many believe safety features should be adjusted only for comfort. Some of the current residual injury producing problems in occupant systems are specifically described here in order to illustrate what is needed in terms of both design remedies and health promotion activities.

Ion temperature profiles in front of a negative planar electrode studied by a one-dimensional two-fluid model

NASA Astrophysics Data System (ADS)

Gyergyek, T.; Kovačič, J.

2016-06-01

Plasma-wall transition is studied by a one-dimensional steady state two-fluid model. Continuity and momentum exchange equations are used for the electrons, while the continuity, momentum exchange, and energy transport equation are used for the ions. Electrons are assumed to be isothermal. The closure of ion equations is made by the assumption that the heat flux is zero. The model equations are solved for potential, ion and electron density, and velocity and ion temperature as independent variables. The model includes coulomb collisions between ions and electrons and charge exchange collisions between ions and neutral atoms of the same species and same mass. The neutral atoms are assumed to be essentially at rest. The model is solved for finite ratio ɛ = /λ D L between the Debye length and λD and ionization length L in the pre-sheath and in the sheath at the same time. Charge exchange collisions heat the ions in the sheath and the pre-sheath. Even a small increase of the frequency of charge exchange collisions causes a substantial increase of ion temperature. Coulomb collisions have negligible effect on ion temperature in the pre-sheath, while in the sheath they cause a small cooling of ions. The increase of ɛ causes the increase of ion temperature. From the ion density and temperature profiles, the polytropic function κ is calculated according to its definition given by Kuhn et al. [Phys. Plasmas 13, 013503 (2006)]. The obtained profiles of κ indicate that the ion flow is isothermal only in a relatively narrow region in the pre-sheath, while close to the sheath edge and in the sheath it is closer to adiabatic. The ion sound velocity is space dependent and exhibits a maximum. This maximum indicates the location of the sheath edge only in the limit ɛ → 0 .

Frankfurt, Germany: 1030/1090 MegaHertz Signal Analysis

DOT National Transportation Integrated Search

1996-07-01

The Data Link Test Analysis System (DATAS) was used in the Frankfort, Germany : to collect data in the frequency band used by Air Traffic Control Radar : Beacon (ATCRBS), Mode Select (Mode S), and Traffic Alert and Collision : Avoidance (TCAS). Data ...

Effect of viscosity on droplet-droplet collisional interaction

NASA Astrophysics Data System (ADS)

Finotello, Giulia; Padding, Johan T.; Deen, Niels G.; Jongsma, Alfred; Innings, Fredrik; Kuipers, J. A. M.

2017-06-01

A complete knowledge of the effect of droplet viscosity on droplet-droplet collision outcomes is essential for industrial processes such as spray drying. When droplets with dispersed solids are dried, the apparent viscosity of the dispersed phase increases by many orders of magnitude, which drastically changes the outcome of a droplet-droplet collision. However, the effect of viscosity on the droplet collision regime boundaries demarcating coalescence and reflexive and stretching separation is still not entirely understood and a general model for collision outcome boundaries is not available. In this work, the effect of viscosity on the droplet-droplet collision outcome is studied using direct numerical simulations employing the volume of fluid method. The role of viscous energy dissipation is analysed in collisions of droplets with different sizes and different physical properties. From the simulations results, a general phenomenological model depending on the capillary number (Ca, accounting for viscosity), the impact parameter (B), the Weber number (We), and the size ratio (Δ) is proposed.

Method and apparatus for measuring frequency and phase difference

NASA Technical Reports Server (NTRS)

Shores, Paul (Inventor); Lichtenberg, Christopher (Inventor); Kobayashi, Herbert S. (Inventor); Cunningham, Allen R. (Inventor)

1986-01-01

The present invention is a system for deriving direct digital indications of frequency and phase difference between two incoming pulse trains adaptable for collision avoidance systems or the like. A pair of radar beams are directed toward a target and corresponding beams returning therefrom are detected. A digital difference circuit forms a pulse train from the Doppler shift frequencies of each beam pair having a repetition rate functionally related to the difference in magnitude of the shift frequencies. Pulses from the pulse train are counted as a function of time. Visual indications thereof on display are correlative to target position relative to beams.

Damping of gravitational waves by matter

NASA Astrophysics Data System (ADS)

Baym, Gordon; Patil, Subodh P.; Pethick, C. J.

2017-10-01

We develop a unified description, via the Boltzmann equation, of damping of gravitational waves by matter, incorporating collisions. We identify two physically distinct damping mechanisms—collisional and Landau damping. We first consider damping in flat spacetime, and then generalize the results to allow for cosmological expansion. In the first regime, maximal collisional damping of a gravitational wave, independent of the details of the collisions in the matter is, as we show, significant only when its wavelength is comparable to the size of the horizon. Thus damping by intergalactic or interstellar matter for all but primordial gravitational radiation can be neglected. Although collisions in matter lead to a shear viscosity, they also act to erase anisotropic stresses, thus suppressing the damping of gravitational waves. Damping of primordial gravitational waves remains possible. We generalize Weinberg's calculation of gravitational wave damping, now including collisions and particles of finite mass, and interpret the collisionless limit in terms of Landau damping. While Landau damping of gravitational waves cannot occur in flat spacetime, the expansion of the universe allows such damping by spreading the frequency of a gravitational wave of given wave vector.

Particle in cell/Monte Carlo collision analysis of the problem of identification of impurities in the gas by the plasma electron spectroscopy method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kusoglu Sarikaya, C.; Rafatov, I., E-mail: rafatov@metu.edu.tr; Kudryavtsev, A. A.

2016-06-15

The work deals with the Particle in Cell/Monte Carlo Collision (PIC/MCC) analysis of the problem of detection and identification of impurities in the nonlocal plasma of gas discharge using the Plasma Electron Spectroscopy (PLES) method. For this purpose, 1d3v PIC/MCC code for numerical simulation of glow discharge with nonlocal electron energy distribution function is developed. The elastic, excitation, and ionization collisions between electron-neutral pairs and isotropic scattering and charge exchange collisions between ion-neutral pairs and Penning ionizations are taken into account. Applicability of the numerical code is verified under the Radio-Frequency capacitively coupled discharge conditions. The efficiency of the codemore » is increased by its parallelization using Open Message Passing Interface. As a demonstration of the PLES method, parallel PIC/MCC code is applied to the direct current glow discharge in helium doped with a small amount of argon. Numerical results are consistent with the theoretical analysis of formation of nonlocal EEDF and existing experimental data.« less

A Study of Alfven Wave Propagation and Heating the Chromosphere

NASA Astrophysics Data System (ADS)

Tu, J.; Song, P.

2013-12-01

Alfven wave propagation, reflection and heating of the solar atmosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma and neutral fluid equations and Maxwell's equations with incorporation of the Hall effect, strong electron-neutral, electron-ion, and ion-neutral collisions. The governing equations are very stiff because of the strong coupling between the charged and neutral fluids. We have developed a numerical model based on an implicit backward difference formula (BDF2) of second order accuracy both in time and space to overcome the stiffness. A non-reflecting boundary condition is applied to the top boundary of the simulation domain so that the wave reflection within the domain due to the density gradient can be unambiguously determined. It is shown that the Alfven waves are partially reflected throughout the chromosphere. The reflection is increasingly stronger at higher altitudes and the strongest reflection occurs at the transition region. The waves are damped in the lower chromosphere dominantly through Joule dissipation due to electron collisions with neutrals and ions. The heating resulting from the wave damping is strong enough to balance the radiation energy loss for the quiet chromosphere. The collisional dissipation of the Alfven waves in the weakly collisional corona is negligible. The heating rates are larger for weaker background magnetic fields. In addition, higher frequency waves are subject to heavier damping. There is an upper cutoff frequency, depending on the background magnetic field, above which the waves are completely damped. At the frequencies below which the waves are not strongly damped, the waves may be strongly reflected at the transition region. The reflected waves interacting with the upward propagating waves may produce power at their double frequencies, which leads to more damping. Due to the reflection and damping, the energy flux of the waves transmitted to the corona is one order of magnitude smaller than that of the driving source.

Collision Avoidance W-Band FMCW Radars in an Altimeter Application

DTIC Science & Technology

2006-08-01

underground mining applications. Potentially, a small low– powered downward looking aerial radar employing Frequency Modulated Continuous Wave (FMCW) ranging...frequency [1]. 3 Figure 3: Epsilon Lambda ELF 171-1A radar. Model and System block diagram [2]. 4 Figure 4: Beam limited resolution cell (after [3]). 6...Figure 5: (black curves) Projected SNR variation of clutter return with range for ELF 171-1A type system in different weather conditions. Clutter-to

TacSats for Surveillance, Verification and C3I

DTIC Science & Technology

1993-02-01

a single significant fraction of the L.V. payload satellite of an identical total mass. and will reduce, in proportion , the Assuming the availability...power limited proportional to gas pressure; F= frequency lightsats: of the applied RF field. - small ion thrusters for drag At resonance F=Fc, and the...thrusters ir also the collision frequency proportional to required. Full thrust control, over a 30% the operating gas pressure. to 120 % range of the design

Evolution of Cometary Dust Particles to the Orbit of the Earth: Particle Size, Shape, and Mutual Collisions

NASA Astrophysics Data System (ADS)

Yang, Hongu; Ishiguro, Masateru

2018-02-01

In this study, we numerically investigated the orbital evolution of cometary dust particles, with special consideration of the initial size–frequency distribution (SFD) and different evolutionary tracks according to the initial orbit and particle shape. We found that close encounters with planets (mostly Jupiter) are the dominating factor determining the orbital evolution of dust particles. Therefore, the lifetimes of cometary dust particles (∼250,000 yr) are shorter than the Poynting–Robertson lifetime, and only a small fraction of large cometary dust particles can be transferred into orbits with small semimajor axes. The exceptions are dust particles from 2P/Encke and, potentially, active asteroids that have little interaction with Jupiter. We also found that the effects of dust shape, mass density, and SFD were not critical in the total mass supply rate to the interplanetary dust particle (IDP) cloud complex when these quantities are confined by observations of zodiacal light brightness and SFD around the Earth’s orbit. When we incorporate a population of fluffy aggregates discovered in the Earth’s stratosphere and the coma of 67P/Churyumov–Gerasimenko within the initial ejection, the initial SFD measured at the comae of comets (67P and 81P/Wild 2) can produce the observed SFD around the Earth’s orbit. Considering the above effects, we derived the probability of mutual collisions among dust particles within the IDP cloud for the first time in a direct manner via numerical simulation and concluded that mutual collisions can mostly be ignored.

Recent progress on the cold atoms clocks at BNM-LPTF

NASA Astrophysics Data System (ADS)

Abgrall, M.; Lemonde, P.; Bize, S.; Sortais, Y.; Zhang, S.; Santarelli, G.; Laurent, P.; Clairon, A.; Salomon, C.

We present recent results on microwave frequency standards using cold atoms. Two cesium fountains have been built and exhibit a frequency accuracy of 1×10-15. Though quite different in their design, both fountains are found to give the same frequency within the error bars of the measurements. One of the fountains is transportable. It was moved to Germany and used as a reference for a phase coherent measurement of the 1S-2S transition of hydrogen with a 2×10-14 accuracy. When using a cryogenic sapphire oscillator as an interrogation oscillator, the frequency stability reaches the fundamental limit set by the quantum projection noise. A short term stability of 4×10-14 τ-1/2 has been obtained. One limitation to the performances of cesium fountains is the frequency shift due to collisions between cold atoms. We show that with rubidium atoms, this effect can be decreased by two orders of magnitude. This feature should allow to vastly improve both the stability and accuracy of microwave fountains. Finally by tracking the frequency between rubidium and cesium fountains, we test the stability of the fine structure constant α with a few 10-15 resolution. We also present the status of the ACES space project.

A THEORETICAL TREATMENT OF THE STEADY-FLOW, LINEAR, CROSSED-FIELD, DIRECT- CURRENT PLASMA ACCELERATOR FOR INVISCID, ADIABATIC, ISOTHERMAL, CONSTANTAREA FLOW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, G.P.; Carter, A.F.; Lintz, H.K.

1961-01-01

The theory is developed from the individual equations fo motion of the three componenets of the plasma. The effect of the ion cyclotron angle omega tau, which is the product of the ion cyclotron frequency and the ion mean free time between collisions with neutral particles and which is proportional to the axial component of the ion slip velocity, on both Joule heating rate and accelerator length is included in the results and is shown to be small only for values of about 10/sup -3/ radian or less. (auth)

2D scanning Rotman lens structure for smart collision avoidance sensors

NASA Astrophysics Data System (ADS)

Hall, Leonard T.; Hansen, Hedley J.; Abbott, Derek

2004-03-01

Although electronically scanned antenna arrays can provide effective mm-wave search radar sensors, their high cost and complexity are leading to the consideration of alternative beam-forming arrangements. Rotman lenses offer a compact, rugged, reliable, alternative solution. This paper considers the design of a microstrip based Rotman lens for high-resolution, frequency-controlled scanning applications. Its implementation in microstrip is attractive because this technology is low-cost, conformal, and lightweight. A sensor designed for operation at 77 GHz is presented and an ~80° azimuthal scan over a 30 GHz bandwidth is demonstrated.

Dark soliton interaction of spinor Bose-Einstein condensates in an optical lattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Zaidong; Li Qiuyan

2007-08-15

We study the magnetic soliton dynamics of spinor Bose-Einstein condensates in an optical lattice which results in an effective Hamiltonian of anisotropic pseudospin chain. An equation of nonlinear Schroedinger type is derived and exact magnetic soliton solutions are obtained analytically by means of Hirota method. Our results show that the critical external field is needed for creating the magnetic soliton in spinor Bose-Einstein condensates. The soliton size, velocity and shape frequency can be controlled in practical experiment by adjusting the magnetic field. Moreover, the elastic collision of two solitons is investigated in detail.

A Theoretical Treatment of the Steady-Flow, Linear, Crossed-Field, Direct-Current Plasma Accelerator for Inviscid, Adiabatic, Isothermal, Constant-Area Flow

NASA Technical Reports Server (NTRS)

Wood, George P.; Carter, Arlen F.; Lintz, Hubert K.; Pennington, J. Byron

1961-01-01

The theory is developed from the individual equations of motion of the three components of the plasma. The effect of the ion cyclotron angle (omega tau), which is the product of the ion cyclotron frequency and the ion mean free time between collisions with neutral particles and which is proportional to the axial component of the ion slip velocity, on both Joule heating rate and accelerator length is included in the results and is shown to be small only for values of about 10(exp -3) radian or less.

Quantified Energy Dissipation Rates in the Terrestrial Bow Shock. 2; Waves and Dissipation

NASA Technical Reports Server (NTRS)

Wilson, L. B., III; Sibeck, D. G.; Breneman, A. W.; Le Contel, O.; Cully, C.; Turner, D. L.; Angelopoulos, V.; Malaspina, D. M.

2014-01-01

We present the first quantified measure of the energy dissipation rates, due to wave-particle interactions, in the transition region of the Earth's collision-less bow shock using data from the Time History of Events and Macro-Scale Interactions during Sub-Storms spacecraft. Our results show that wave-particle interactions can regulate the global structure and dominate the energy dissipation of collision-less shocks. In every bow shock crossing examined, we observed both low-frequency (less than 10 hertz) and high-frequency (approximately or greater than10 hertz) electromagnetic waves throughout the entire transition region and into the magnetosheath. The low-frequency waves were consistent with magnetosonic-whistler waves. The high-frequency waves were combinations of ion-acoustic waves, electron cyclotron drift instability driven waves, electrostatic solitary waves, and whistler mode waves. The high-frequency waves had the following: (1) peak amplitudes exceeding delta B approximately equal to 10 nanoteslas and delta E approximately equal to 300 millivolts per meter, though more typical values were delta B approximately equal to 0.1-1.0 nanoteslas and delta E approximately equal to 10-50 millivolts per meter (2) Poynting fluxes in excess of 2000 microWm(sup -2) (micro-waves per square meter) (typical values were approximately 1-10 microWm(sup -2) (micro-waves per square meter); (3) resistivities greater than 9000 omega meters; and (4) associated energy dissipation rates greater than 10 microWm(sup -3) (micro-waves per cubic meter). The dissipation rates due to wave-particle interactions exceeded rates necessary to explain the increase in entropy across the shock ramps for approximately 90 percent of the wave burst durations. For approximately 22 percent of these times, the wave-particle interactions needed to only be less than or equal to 0.1 percent efficient to balance the nonlinear wave steepening that produced the shock waves. These results show that wave-particle interactions have the capacity to regulate the global structure and dominate the energy dissipation of collision-less shocks.

How did the rings of Uranus form?

NASA Astrophysics Data System (ADS)

Griv, E.

2007-08-01

Uranus is encircled by at least ten narrow, dense, and widely separated rings with a typical optical depth ∼ 0.3, the first nine of which (6, 5, 4, ?, ?, ?, , ?, and ? rings as seen going outward from Uranus) were discovered from the ground during observations of the planet's atmosphere in 1977. In this work, a fairly uniform, rapidly and differentially rotating disk of rarely colliding particles (when the frequency of interparticle collisions is much smaller than the local orbital frequency) in a planet- moon system is considered. A moon causes a number of orbital resonant effects in this continuous viscous (through ordinary collisions) disk. In the frame of hydrodynamical theory, the gravitational torques exerted by an exterior moon on particles at an inner Lindblad horizontal resonance and corresponding vertical resonance are estimated. It is shown that the torques are negative at these resonances, so gaps in the disk near each resonance may be created. The latter result can be used to provide a viable clue to solving of the puzzle of narrow, dense, and widely separated rings of Uranus. The model is advocated which suggests that the Uranian ring orbits have a close connection with small moons of the planet interior to the orbit of Miranda, from Cordelia to Mab discovered by VOYAGER 2 imaging observations in 1986. As angular momentum is transferred outward to the moon, material in the close vicinity of the resonances falls to the inner part of the system under study. On the other hand, in a collision disk the angular momentum is steadily concentrated onto a fraction of the mass which is spiraling away. In Uranus' system, this viscous radial spreading of the disk (and associated outward flow of angular momentum) may be terminated by the torque exerted by the moon via the low-order orbital resonance. This work was jointly supported by the Israel Science Foundation, the Binational U.S.-Israel Science Foundation, and the Israeli Ministry of Immigrant Absorption in the framework of the program "KAMEA."

Thermally assisted infrared multiphoton photodissociation in a quadrupole ion trap.

PubMed

Payne, A H; Glish, G L

2001-08-01

Thermally assisted infrared multiphoton photodissociation (TA-IRMPD) provides an effective means to dissociate ions in the quadrupole ion trap mass spectrometer (QITMS) without detrimentally affecting the performance of the instrument. IRMPD can offer advantages over collision-induced dissociation (CID). However, collisions with the QITMS bath gas at the standard pressure and ambient temperature cause IR-irradiated ions to lose energy faster than photons can be absorbed to induce dissociation. The low pressure required for IRMPD (< or = 10(-5) Torr) is not that required for optimal performance of the QITMS (10(-3) Torr), and sensitivity and resolution suffer. TA-IRMPD is performed with the bath gas at an elevated temperature. The higher temperature of the bath gas results in less energy lost in collisions of the IR-excited ions with the bath gas. Thermal assistance allows IRMPD to be used at or near optimal pressures, which results in an approximately 1 order of magnitude increase in signal intensity. Unlike CID, IRMPD allows small product ions, those less than about one-third the m/z of the parent ion, to be observed. IRMPD should also be more easily paired with fluctuating ion sources, as the corresponding fluctuations in resonant frequencies do not affect IRMPD. Finally, while IR irradiation nonselectively causes dissociation of all ions, TA-IRMPD can be made selective by using axial expansion to move ions away from the path of the laser beam.

\\psi (2S) enhancement in p-Pb collision as an indication of quark-gluon plasma formation at the Large Hadron Collider

NASA Astrophysics Data System (ADS)

Ganesh, S.; Singh, R., Captain; Mishra, M.

2018-03-01

Proton-nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus-nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and Relativistic Heavy-Ion Collider energies for the past several years, as it was thought that quark-gluon plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton-lead (p-Pb) collisions. In this work, we have derived an expression for gluon induced excitation of J/\\psi to \\psi (2S), using pNRQCD, and show that the relative enhancement of \\psi (2S) vis-à-vis J/\\psi , especially at high p T , gives further indication that the QGP is indeed formed in p-Pb collisions at the most central collisions at LHC energy. J/\\psi and \\psi (2S) suppression effects seen at ALICE are also qualitatively explained.

A Monte Carlo simulation of the effect of ion self-collisions on the ion velocity distribution function in the high-latitude F-region

NASA Technical Reports Server (NTRS)

Barghouthi, I. A.; Barakat, A. R.; Schunk, R. W.

1994-01-01

Non-Maxwellian ion velocity distribution functions have been theoretically predicted and confirmed by observations, to occur at high latitudes. These distributions deviate from Maxwellian due to the combined effect of the E x B drift and ion-neutral collisions. At high altitude and/or for solar maximum conditions, the ion-to-neutral density ratio increases and, hence, the role of ion self-collisions becomes appreciable. A Monte Carlo simulation was used to investigate the behavior of O(+) ions that are E x B-drifting through a background of neutral O, with the effect of O(+) (Coulomb) self-collisions included. Wide ranges of the ion-to-neutral density ratio n(sub i)/n(sub n) and the electrostatic field E were considered in order to investigate the change of ion behavior with solar cycle and with altitude. For low altitudes and/or solar minimum (n(sub i)/n(sub n) less than or equal to 10(exp -5)), the effect of self-collisions is negligible. For higher values of n(sub i)/n(sub n), the effect of self-collisions becomes significant and, hence, the non-Maxwellian features of the O(+) distribution are reduced. The Monte Carlo results were compared to those that used simplified collision models in order to assess their validity. In general, the simple collision models tend to be more accurate for low E and for high n(sub i)/n(sub n).

Effectiveness of light-reflecting devices: A systematic reanalysis of animal-vehicle collision data.

PubMed

Brieger, Falko; Hagen, Robert; Vetter, Daniela; Dormann, Carsten F; Storch, Ilse

2016-12-01

Every year, approximately 500 human fatalities occur due to animal-vehicle collisions in the United States and Europe. Especially heavy-bodied animals affect road safety. For more than 50 years, light-reflecting devices such as wildlife warning reflectors have been employed to alert animals to traffic when crossing roads during twilight and night. Numerous studies addressed the effectiveness of light-reflecting devices in reducing collisions with animals in past decades, but yielded contradictory results. In this study, we conducted a systematic literature review to investigate whether light-reflecting devices contribute to an effective prevention of animal-vehicle collisions. We reviewed 53 references and reanalyzed original data of animal-vehicle collisions with meta-analytical methods. We calculated an effect size based on the annual number of animal-vehicle collisions per kilometer of road to compare segments with and without the installation of light-reflecting devices for 185 roads in Europe and North America. Our results indicate that light-reflecting devices did not significantly reduce the number of animal-vehicle collisions. However, we observed considerable differences of effect sizes with respect to study duration, study design, and country. Our results suggest that length of the road segment studied, study duration, study design and public attitude (preconception) to the functioning of devices may affect whether the documented number of animal-vehicle collisions in- or decrease and might in turn influence whether results obtained were published. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electron impact collision strengths in Ne VII

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di, L.; Shi, J.R.; Zhao, G., E-mail: gzhao@bao.ac.cn

2012-07-15

The lines of Ne VII have been observed in many astronomical objects, and some transitions from high energy levels were observed both in Seyfert galaxies and stellar coronae. Thus, the atomic data for these transitions are important for modeling. Using the code FAC we calculated the collision strengths based on the distorted-wave method with large configuration interactions included. The Maxwellian averaged effective collision strengths covering the typical temperature range of astronomical and laboratory hot plasmas are presented. We extend the calculation of the energy levels to n=4 and 5. The energy levels, wavelengths, spontaneous transition rates, weighted oscillator strengths, andmore » effective collision strengths were reported. Compared with the results from experiment or previous theoretical calculations a general agreement is found. It is found that the resonance effects are important in calculating the effective collision strengths.« less

Strong Lg-wave attenuation in the Middle East continental collision orogenic belt

NASA Astrophysics Data System (ADS)

Zhao, Lian-Feng; Xie, Xiao-Bi

2016-04-01

Using Lg-wave Q tomography, we construct a broadband crustal attenuation model for the Middle East. The QLg images reveal a relationship between attenuation and geological structures. Strong attenuation is found in the continental collision orogenic belt that extends from the Turkish and Iranian plateau to the Pamir plateau. We investigate the frequency dependence of QLg in different geologic formations. The results illustrate that QLg values generally increase with increasing frequency but exhibit complex relationships both with frequency and between regions. An average QLg value between 0.2 and 2.0 Hz, QLg (0.2-2.0 Hz), may be a critical index for crustal attenuation and is used to infer the regional geology. Low-QLg anomalies are present in the eastern Turkish plateau and correlate well with low Pn-velocities and Cenozoic volcanic activity, thus indicating possible partial melting within the crust in this region. Very strong attenuation is also observed in central Iran, the Afghanistan block, and the southern Caspian Sea. This in line with the previously observed high crustal temperature, high-conductivity layers, and thick marine sediments in these areas, suggests the high Lg attenuation is caused by abnormally high tectonic and thermal activities.

Shadowing effects on J/ψ and Υ production at energies available at the CERN Large Hadron Collider

DOE PAGES

Vogt, R.

2015-09-17

Proton-nucleus collisions have been used as a intermediate baseline for the determination of cold medium effects. They lie between proton-proton collisions in vacuum and nucleus-nucleus collisions which are expected to be dominated by hot matter effects. Modifications of the quark densities in nuclei relative to those of the proton are well established although those of the gluons in the nucleus are not well understood. We focus on the effect of these on quarkonium production in proton-lead collisions at the LHC at a center of mass energy of 5.02 TeV.

Can-Filled Crash Barrier

NASA Technical Reports Server (NTRS)

Wilson, A. H.

1983-01-01

Crash barrier composed largely of used aluminum beverage cans protects occupants of cars in collisions with poles or trees. Lightweight, can-filled barrier very effective in softening impact of an automobile in head-on and off-angle collisions. Preliminary results indicate barrier is effective in collisions up to 40 mi/h (64 km/h).

Frequency of distracting tasks people do while driving : an analysis of the ACAS FOT data.

DOT National Transportation Integrated Search

2007-06-01

This report describes further analysis of data from the advanced collision avoidance system (ACAS) field operational test, a naturalistic driving study. To determine how distracted and nondistracted driving differ, a stratified sample of 2,914 video ...

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Efficiencies of state and velocity-changing collisions of superthermal CN A(2)Pi with He, Ar, N(2) and O(2).

PubMed

Alagappan, Azhagammai; Ballingall, Iain; Costen, Matthew L; McKendrick, Kenneth G; Paterson, Grant

2007-02-14

Polarized laser photolysis of ICN is combined with saturated optical pumping to prepare state-selected CN Alpha(2)Pi (nu' = 4, J = 0.5, F(2), f) with a well-defined anisotropic superthermal speed distribution. The collisional evolution of the prepared state is observed by Doppler-resolved Frequency Modulated (FM) spectroscopy via stimulated emission on the CN Alpha(2)Pi-Chi(2)Sigma(+) (4,2) band. The phenomenological rate constants for removal of the prepared state in collisions with He, Ar, N(2) and O(2) are reported. The observed collision cross-sections are consistent with attractive forces contributing significantly for all the colliders with the exception of He. The collisional evolution of the prepared velocity distribution demonstrates that no significant back-transfer into the prepared level occurs, and that any elastic scattering is strongly in the forward hemisphere.

Absolute frequency of cesium 6S-8S 822 nm two-photon transition by a high-resolution scheme.

PubMed

Wu, Chien-Ming; Liu, Tze-Wei; Wu, Ming-Hsuan; Lee, Ray-Kuang; Cheng, Wang-Yau

2013-08-15

We present an alternative scheme for determining the frequencies of cesium (Cs) atom 6S-8S Doppler-free transitions. With the use of a single electro-optical crystal, we simultaneously narrow the laser linewidth, lock the laser frequency, and resolve a narrow spectrum point by point. The error budget for this scheme is presented, and we prove that the transition frequency obtained from the Cs cell at room temperature and with one-layer μ-metal shielding is already very near that for the condition of zero collision and zero magnetic field. We point out that a sophisticated linewidth measurement could be a good guidance for choosing a suitable Cs cell for better frequency accuracy.

Analysis of electromagnetic scattering characteristics of plasma sheath surrounding a hypersonic aerocraft based on high-order auxiliary differential equation finite-difference time-domain

NASA Astrophysics Data System (ADS)

Sun, Hao-yu; Cui, Zhiwei; Wang, Jiajie; Han, Yiping; Sun, Peng; Shi, Xiaowei

2018-06-01

A numerical analysis of electromagnetic (EM) scattering characteristics of a hypersonic aerocraft enveloped by a plasma sheath is presented. The flow field parameters around a hypersonic aerocraft are derived by numerically solving the Navier-Stokes equations. Through multiphysics coupling of flow field and electromagnetic field, distributions of plasma frequency and collision frequency in plasma sheaths are obtained. A high-order auxiliary differential equation finite-difference time-domain algorithm is employed to investigate the EM wave scattering properties of the aerocraft covered by a plasma sheath. The backward radar cross sections (RCSs) of a blunt cone in the hypersonic flows at different velocities and altitudes with frequencies from 0.1 GHz to 18 GHz are studied. Numerical results show that, for the cases of altitude ranging from 50 km to 55 km and velocity ranging from 18 Ma to 20 Ma, the plasma sheath enhances the backscattering of the blunt cone when frequencies are below 1.5 GHz, and it reduces the backward RCSs of the blunt cone as frequency ranges from 1.5 GHz to 13.5 GHz. The plasma sheath has a larger attenuation effect for frequency lying in the range of 2 GHz to 6 GHz, but it has little influence on the backward electromagnetic scattering characteristics when frequencies are above 14 GHz.

Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nunomura, Shota; Kondo, Michio; Shiratani, Masaharu

2008-08-15

The kinetics of nanoparticle coagulation has been studied in fractionally charged and charge fluctuating dusty plasmas. The coagulation occurs when the mutual collision frequency among nanoparticles exceeds their charging and decharging/neutralization frequency. Interestingly, the coagulation is suppressed while a fraction (several percent) of nanoparticles are negatively charged in a plasma, in which stochastic charging plays an important role. A model is developed to predict a phase diagram of the coagulation and its suppression.

Test and Evaluation of the Time/Frequency Collision Avoidance System Concept.

DTIC Science & Technology

1973-09-01

cumulative distributions were then plotted on “normal” graph paper , i.e., graph paper on whit..h a normal distribution will plot as a straight line...apparent problems. 6-8 _ _ _ _ _ _ _ _ _ _ _ _ _ CIMP TER SEVEN CONCLUSIONS AND RECOMMENDAT IONS 7. 1 CONCLUSIONS The time/frequency technique for...instrumentation due to waiting for an event that will not occur , there are time—outs that cause the process to step past the event in questions . In this

Influence of Kohn singularity on the occurrence scattering time in degenerate quantum collisional plasmas

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-10-01

The influence of Kohn singularity on the occurrence scattering time for the electron-ion interaction is investigated in degenerate quantum collisional plasmas. The first-order eikonal analysis is used to obtain the scattering amplitude and the occurrence scattering time. The result shows that the Friedel oscillation due to the Kohn singularity suppresses the advance phenomena of occurrence scattering time in both forward and backward scattering domains. It is shown that the increase of plasmon energy would reduce the time advance for both forward and backward scattering domains. However, the increase of Fermi energy would enhance the phenomena of time advance. It is also found that the time advance with high collision frequency is larger than that with low collision frequency for the forward scattering domain and vice versa for the backward scattering domain. We have shown that the time advance is stronger in general for the forward scattering domain than that for the backward scattering domain.

Collision-induced Absorption in the Infrared: A Data Base for Modelling Planetary and Stellar Atmospheres

NASA Technical Reports Server (NTRS)

Borysow, Aleksandra

1998-01-01

Accurate knowledge of certain collision-induced absorption continua of molecular pairs such as H2-H2, H2-He, H2-CH4, CO2-CO2, etc., is a prerequisite for most spectral analyses and modelling attempts of atmospheres of planets and cold stars. We collect and regularly update simple, state of the art computer programs for the calculation of the absorption coefficient of such molecular pairs over a broad range of temperatures and frequencies, for the various rotovibrational bands. The computational results are in agreement with the existing laboratory measurements of such absorption continua, recorded with a spectral resolution of a few wavenumbers, but reliable computational results may be expected even in the far wings, and at temperatures for which laboratory measurements do not exist. Detailed information is given concerning the systems thus studied, the temperature and frequency ranges considered, the rotovibrational bands thus modelled, and how one may obtain copies of the FORTRAN77 computer programs by e-mail.

Transport and equilibrium in field-reversed mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyd, J.K.

Two plasma models relevant to compact torus research have been developed to study transport and equilibrium in field reversed mirrors. In the first model for small Larmor radius and large collision frequency, the plasma is described as an adiabatic hydromagnetic fluid. In the second model for large Larmor radius and small collision frequency, a kinetic theory description has been developed. Various aspects of the two models have been studied in five computer codes ADB, AV, NEO, OHK, RES. The ADB code computes two dimensional equilibrium and one dimensional transport in a flux coordinate. The AV code calculates orbit average integralsmore » in a harmonic oscillator potential. The NEO code follows particle trajectories in a Hill's vortex magnetic field to study stochasticity, invariants of the motion, and orbit average formulas. The OHK code displays analytic psi(r), B/sub Z/(r), phi(r), E/sub r/(r) formulas developed for the kinetic theory description. The RES code calculates resonance curves to consider overlap regions relevant to stochastic orbit behavior.« less

Measurement of Electron Density and Ion Collision Frequency with Dual Assisted Grounded Electrode DBD in Atmospheric Pressure Helium Plasma Jet

NASA Astrophysics Data System (ADS)

Zhou, Qiujiao; Qi, Bing; Huang, Jianjun; Pan, Lizhu; Liu, Ying

2016-04-01

The properties of a helium atmospheric-pressure plasma jet (APPJ) are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device. In the glow discharge, we captured the current waveforms at the positions of the three grounded rings. From the current waveforms, the time delay between the adjacent positions of the rings is employed to calculate the plasma bullet velocity of the helium APPJ. Moreover, the electron density is deduced from a model combining with the time delay and current intensity, which is about 1011 cm-3. In addition, The ion-neutral particles collision frequency in the radial direction is calculated from the current phase difference between two rings, which is on the order of 107 Hz. The results are helpful for understanding the basic properties of APPJs. supported by National Natural Science Foundation of China (No. 11105093), the Technological Project of Shenzhen, China (No. JC201005280485A), and the Planned S&T Program of Shenzhen, China (No. JC201105170703A)

Effect of the fluctuating proton size on the study of the chiral magnetic effect in proton-nucleus collisions

NASA Astrophysics Data System (ADS)

Kharzeev, Dmitri; Tu, Zhoudunming; Zhang, Aobo; Li, Wei

2018-02-01

High energy proton-nucleus (pA) collisions provide an important constraint on the study of the chiral magnetic effect in QCD matter. Naively, in pA collisions one expects no correlation between the orientation of the event plane as reconstructed from the azimuthal distribution of produced hadrons and the orientation of the magnetic field. If this is the case, any charge-dependent hadron correlations can only result from the background. Nevertheless, in this paper we point out that in high multiplicity pA collisions a correlation between the magnetic field and the event plane can appear. This is because triggering on the high hadron multiplicity amounts to selecting Fock components of the incident proton with a large number of partons that are expected to have a transverse size much larger than the average proton size. We introduce the effect of the fluctuating proton size in the Monte Carlo Glauber model and evaluate the resulting correlation between the magnetic field and the second-order event plane in both pA and nucleus-nucleus (AA) collisions. The fluctuating proton size is found to result in a significant correlation between the magnetic field and the event plane in pA collisions, even though the magnitude of the correlation is still much smaller than in AA collisions. This result opens a possibility of studying the chiral magnetic effect in small systems.

The dynamical evolution of transiting planetary systems including a realistic collision prescription

NASA Astrophysics Data System (ADS)

Mustill, Alexander J.; Davies, Melvyn B.; Johansen, Anders

2018-05-01

Planet-planet collisions are a common outcome of instability in systems of transiting planets close to the star, as well as occurring during in-situ formation of such planets from embryos. Previous N-body studies of instability amongst transiting planets have assumed that collisions result in perfect merging. Here, we explore the effects of implementing a more realistic collision prescription on the outcomes of instability and in-situ formation at orbital radii of a few tenths of an au. There is a strong effect on the outcome of the growth of planetary embryos, so long as the debris thrown off in collisions is rapidly removed from the system (which happens by collisional processing to dust, and then removal by radiation forces) and embryos are small (<0.1 M⊕). If this is the case, then systems form fewer detectable (≥1 M⊕) planets than systems evolved under the assumption of perfect merging in collisions. This provides some contribution to the "Kepler Dichotomy": the observed over-abundance of single-planet systems. The effects of changing the collision prescription on unstable mature systems of super-Earths are less pronounced. Perfect mergers only account for a minority of collision outcomes in such systems, but most collisions resulting in mass loss are grazing impacts in which only a few per cent. of mass is lost. As a result, there is little impact on the final masses and multiplicities of the systems after instability when compared to systems evolved under the assumption that collisions always result in perfect merging.

Gamma ray bursts from extragalactic sources

NASA Technical Reports Server (NTRS)

Hoyle, Fred; Burbidge, Geoffrey

1992-01-01

The properties of gamma ray bursts of classical type are found to be explicable in terms of high speed collisions between stars. A model is proposed in which the frequency of such collisions can be calculated. The model is then applied to the nuclei of galaxies in general on the basis that galaxies, or at least some fraction of them, originate in the expulsion of stars from creation centers. Evidence that low level activity of this kind is also taking place at the center of our own Galaxy is discussed. The implications for galactic evolution are discussed and a negative view of black holes is taken.

Power coupling mode transitions induced by tailored voltage waveforms in capacitive oxygen discharges

NASA Astrophysics Data System (ADS)

Derzsi, Aranka; Bruneau, Bastien; Gibson, Andrew Robert; Johnson, Erik; O'Connell, Deborah; Gans, Timo; Booth, Jean-Paul; Donkó, Zoltán

2017-03-01

Low-pressure capacitively coupled radio frequency discharges operated in O2 and driven by tailored voltage waveforms are investigated experimentally and by means of kinetic simulations. Pulse-type (peaks/valleys) and sawtooth-type voltage waveforms that consist of up to four consecutive harmonics of the fundamental frequency are used to study the amplitude asymmetry effect as well as the slope asymmetry effect at different fundamental frequencies (5, 10, and 15 MHz) and at different pressures (50-700 mTorr). Values of the DC self-bias determined experimentally and spatio-temporal excitation rates derived from phase resolved optical emission spectroscopy measurements are compared with particle-in-cell/Monte Carlo collisions simulations. The spatio-temporal distributions of the excitation rate obtained from experiments are well reproduced by the simulations. Transitions of the discharge electron heating mode from the drift-ambipolar mode to the α-mode are induced by changing the number of consecutive harmonics included in the driving voltage waveform or by changing the gas pressure. Changing the number of harmonics in the waveform has a strong effect on the electronegativity of the discharge, on the generation of the DC self-bias and on the control of ion properties at the electrodes, both for pulse-type, as well as sawtooth-type driving voltage waveforms The effect of the surface quenching rate of oxygen singlet delta metastable molecules on the spatio-temporal excitation patterns is also investigated.

Alkylation effects on the energy transfer of highly vibrationally excited naphthalene.

PubMed

Hsu, Hsu Chen; Tsai, Ming-Tsang; Dyakov, Yuri A; Ni, Chi-Kung

2011-11-04

The energy transfer of highly vibrationally excited isomers of dimethylnaphthalene and 2-ethylnaphthalene in collisions with krypton were investigated using crossed molecular beam/time-of-flight mass spectrometer/time-sliced velocity map ion imaging techniques at a collision energy of approximately 300 cm(-1). Angular-resolved energy-transfer distribution functions were obtained directly from the images of inelastic scattering. The results show that alkyl-substituted naphthalenes transfer more vibrational energy to translational energy than unsubstituted naphthalene. Alkylation enhances the V→T energy transfer in the range -ΔE(d)=-100~-1500 cm(-1) by approximately a factor of 2. However, the maximum values of V→T energy transfer for alkyl-substituted naphthalenes are about 1500~2000 cm(-1), which is similar to that of naphthalene. The lack of rotation-like wide-angle motion of the aromatic ring and no enhancement in very large V→T energy transfer, like supercollisions, indicates that very large V→T energy transfer requires special vibrational motions. This transfer cannot be achieved by the low-frequency vibrational motions of alkyl groups. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improving Optical Absorption Models for Harsh Planetary Atmospheres: Laboratory Spectroscopy at Venus Surface Conditions

NASA Astrophysics Data System (ADS)

Cole, Ryan Kenneth; Schroeder, Paul James; Diego Draper, Anthony; Rieker, Gregory Brian

2018-06-01

Modelling absorption spectra in high pressure, high temperature environments is complicated by the increased relevance of higher order collisional phenomena (e.g. line mixing, collision-induced absorption, finite duration of collisions) that alter the spectral lineshape. Accurate reference spectroscopy in these conditions is of interest for mineralogy and radiative transfer studies of Venus as well as other dense planetary atmospheres. We present a new, high pressure, high temperature absorption spectroscopy facility at the University of Colorado Boulder. This facility employs a dual frequency comb absorption spectrometer to record broadband (500nm), high resolution (~0.002nm) spectra in conditions comparable to the Venus surface (730K, 90bar). Measurements of the near-infrared spectrum of carbon dioxide at high pressure and temperature will be compared to modeled spectra extrapolated from the HITRAN 2016 database as well as other published models that include additional collisional physics. This comparison gives insight into the effectiveness of existing absorption databases for modeling the lower Venus atmosphere as well as the need to expand absorption models to suit these conditions.

Cumulative Interference to Aircraft Radios from Multiple Portable Electronic Devices

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.

2005-01-01

Cumulative interference effects from portable electronic devices (PEDs) located inside a passenger cabin are conservatively estimated for aircraft radio receivers. PEDs' emission powers in an aircraft radio frequency band are first scaled according to their locations' interference path loss (IPL) values, and the results are summed to determine the total interference power. The multiple-equipment-factor (MEF) is determined by normalizing the result against the worst case contribution from a single device. Conservative assumptions were made and MEF calculations were performed for Boeing 737's Localizer, Glide-slope, Traffic Collision Avoidance System, and Very High Frequency Communication radio systems where full-aircraft IPL data were available. The results show MEF for the systems to vary between 10 and 14 dB. The same process was also used on the more popular window/door IPL data, and the comparison show the multiple-equipment-factor results came within one decibel (dB) of each other.

Conjunction Assessment Late-Notice High-Interest Event Investigation: Space Weather Aspects

NASA Technical Reports Server (NTRS)

Pachura, D.; Hejduk, M. D.

2016-01-01

Late-notice events usually driven by large changes in primary (protected) object or secondary object state. Main parameter to represent size of state change is component position difference divided by associated standard deviation (epsilon divided by sigma) from covariance. Investigation determined actual frequency of large state changes, in both individual and combined states. Compared them to theoretically expected frequencies. Found that large changes ( (epsilon divided by sigma) is greater than 3) in individual object states occur much more frequently than theory dictates. Effect is less pronounced in radial components and in events with probability of collision (Pc) greater than 1 (sup -5) (1e-5). Found combined state matched much closer to theoretical expectation, especially for radial and cross-track. In-track is expected to be the most vulnerable to modeling errors, so not surprising that non-compliance largest in this component.

Airborne Lidar measurements of the atmospheric pressure profile with tunable Alexandrite lasers

NASA Technical Reports Server (NTRS)

Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Milrod, J.; Walden, H.

1986-01-01

The first remote measurements of the atmospheric pressure profile made from an airborne platform are described. The measurements utilize a differential absorption lidar and tunable solid state Alexandrite lasers. The pressure measurement technique uses a high resolution oxygen A band where the absorption is highly pressure sensitive due to collision broadening. Absorption troughs and regions of minimum absorption were used between pairs of stongly absorption lines for these measurements. The trough technique allows the measurement to be greatly desensitized to the effects of laser frequency instabilities. The lidar system was set up to measure pressure with the on-line laser tuned to the absorption trough at 13147.3/cm and with the reference laser tuned to a nonabsorbing frequency near 13170.0/cm. The lidar signal returns were sampled with a 200 range gate (30 vertical resoltion) and averaged over 100 shots.

The Physics of Marine Fog

NASA Astrophysics Data System (ADS)

Browning, David; Scheifele, Peter

2002-04-01

The "fog-bound" coast of New England has posed a hazard to all forms of transportation for centuries, yet relatively little study, especially in recent times, has been done on the physics of fog. The singular study of sound propagation, conducted in 1959, found no apparent increase over the normal frequency dependent absorption in air. However, a recent text (W. Binhua, SEA FOG, Springer-Verlag, 1985) indicates that this was only a moderate fog and not the much more intense ("killer") fogs. For these the aggregaton of water droplets may lead to increased low frequency absorption thus reducing the effective range of existing foghorns. On land, advances in light scattering might be applied to provide a simple mobile means (mounted on a police car, for example) to quickly identify extreme conditions and take precautionary action on the highway to prevent the horrific multi-car collisions that can occur.

On the Transport and Radiative Properties of Plasmas with Small-Scale Electromagnetic Fluctuations

NASA Astrophysics Data System (ADS)

Keenan, Brett D.

Plasmas with sub-Larmor-scale ("small-scale") electromagnetic fluctuations are a feature of a wide variety of high-energy-density environments, and are essential to the description of many astrophysical/laboratory plasma phenomena. Radiation from particles, whether they be relativistic or non-relativistic, moving through small-scale electromagnetic turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation. The radiation, carrying information on the statistical properties of the turbulence, is also intimately related to the particle diffusive transport. We investigate, both theoretically and numerically, the transport of non-relativistic and transrelativistic particles in plasmas with high-amplitude isotropic sub-Larmor-scale magnetic turbulence---both with and without a mean field component---and its relation to the spectra of radiation simultaneously produced by these particles. Furthermore, the transport of particles through small-scale electromagnetic turbulence---under certain conditions---resembles the random transport of particles---via Coulomb collisions---in collisional plasmas. The pitch-angle diffusion coefficient, which acts as an effective "collision" frequency, may be substantial in these, otherwise, collisionless environments. We show that this effect, colloquially referred to as the plasma "quasi-collisionality", may radically alter the expected radiative transport properties of candidate plasmas. We argue that the modified magneto-optic effects in these plasmas provide an attractive, novel, diagnostic tool for the exploration and characterization of small-scale electromagnetic turbulence. Lastly, we speculate upon the manner in which quasi-collisions may affect inertial confinement fusion (ICF), and other laser-plasma experiments. Finally, we show that mildly relativistic jitter radiation, from laser-produced plasmas, may offer insight into the underlying electromagnetic turbulence. Here we investigate the prospects for, and demonstrate the feasibility of, such direct radiative diagnostics for mildly relativistic, solid-density laser plasmas produced in lab experiments. In effect, we demonstrate how the diffusive and radiative properties of plasmas with small-scale, turbulent, electromagnetic fluctuations may serve as a powerful tool for the diagnosis of laboratory, astrophysical, and space plasmas.

Random parameter models of interstate crash frequencies by severity, number of vehicles involved, collision and location type.

PubMed

Venkataraman, Narayan; Ulfarsson, Gudmundur F; Shankar, Venky N

2013-10-01

A nine-year (1999-2007) continuous panel of crash histories on interstates in Washington State, USA, was used to estimate random parameter negative binomial (RPNB) models for various aggregations of crashes. A total of 21 different models were assessed in terms of four ways to aggregate crashes, by: (a) severity, (b) number of vehicles involved, (c) crash type, and by (d) location characteristics. The models within these aggregations include specifications for all severities (property damage only, possible injury, evident injury, disabling injury, and fatality), number of vehicles involved (one-vehicle to five-or-more-vehicle), crash type (sideswipe, same direction, overturn, head-on, fixed object, rear-end, and other), and location types (urban interchange, rural interchange, urban non-interchange, rural non-interchange). A total of 1153 directional road segments comprising of the seven Washington State interstates were analyzed, yielding statistical models of crash frequency based on 10,377 observations. These results suggest that in general there was a significant improvement in log-likelihood when using RPNB compared to a fixed parameter negative binomial baseline model. Heterogeneity effects are most noticeable for lighting type, road curvature, and traffic volume (ADT). Median lighting or right-side lighting are linked to increased crash frequencies in many models for more than half of the road segments compared to both-sides lighting. Both-sides lighting thereby appears to generally lead to a safety improvement. Traffic volume has a random parameter but the effect is always toward increasing crash frequencies as expected. However that the effect is random shows that the effect of traffic volume on crash frequency is complex and varies by road segment. The number of lanes has a random parameter effect only in the interchange type models. The results show that road segment-specific insights into crash frequency occurrence can lead to improved design policy and project prioritization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Calculation of ground state rotational populations for kinetic gas homonuclear diatomic molecules including electron-impact excitation and wall collisions.

PubMed

Farley, David R

2010-09-07

A model has been developed to calculate the ground state rotational populations of homonuclear diatomic molecules in kinetic gases, including the effects of electron-impact excitation, wall collisions, and gas feed rate. The equations are exact within the accuracy of the cross sections used and of the assumed equilibrating effect of wall collisions. It is found that the inflow of feed gas and equilibrating wall collisions can significantly affect the rotational distribution in competition with nonequilibrating electron-impact effects. The resulting steady-state rotational distributions are generally Boltzmann for N≥3, with a rotational temperature between the wall and feed gas temperatures. The N=0,1,2 rotational level populations depend sensitively on the relative rates of electron-impact excitation versus wall collision and gas feed rates.

Gaze movements and spatial working memory in collision avoidance: a traffic intersection task

PubMed Central

Hardiess, Gregor; Hansmann-Roth, Sabrina; Mallot, Hanspeter A.

2013-01-01

Street crossing under traffic is an everyday activity including collision detection as well as avoidance of objects in the path of motion. Such tasks demand extraction and representation of spatio-temporal information about relevant obstacles in an optimized format. Relevant task information is extracted visually by the use of gaze movements and represented in spatial working memory. In a virtual reality traffic intersection task, subjects are confronted with a two-lane intersection where cars are appearing with different frequencies, corresponding to high and low traffic densities. Under free observation and exploration of the scenery (using unrestricted eye and head movements) the overall task for the subjects was to predict the potential-of-collision (POC) of the cars or to adjust an adequate driving speed in order to cross the intersection without collision (i.e., to find the free space for crossing). In a series of experiments, gaze movement parameters, task performance, and the representation of car positions within working memory at distinct time points were assessed in normal subjects as well as in neurological patients suffering from homonymous hemianopia. In the following, we review the findings of these experiments together with other studies and provide a new perspective of the role of gaze behavior and spatial memory in collision detection and avoidance, focusing on the following questions: (1) which sensory variables can be identified supporting adequate collision detection? (2) How do gaze movements and working memory contribute to collision avoidance when multiple moving objects are present and (3) how do they correlate with task performance? (4) How do patients with homonymous visual field defects (HVFDs) use gaze movements and working memory to compensate for visual field loss? In conclusion, we extend the theory of collision detection and avoidance in the case of multiple moving objects and provide a new perspective on the combined operation of external (bottom-up) and internal (top-down) cues in a traffic intersection task. PMID:23760667

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/c

Design and operation specifications of an active monitoring system for detecting southern resident killer whales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Zhiqun; Carlson, Thomas J.; Xu, Jinshan

2011-09-30

Before final approval is given to the Snohomish County Public Utility District No. 1 for deploying the first tidal power devices in the United States in an open water environment, a system to manage the potential risk of injury to killer whales due to collision with moving turbine blades must be demonstrated. The Pacific Northwest National Laboratory (PNNL) is tasked with establishing the performance requirements for, constructing, and testing a prototype marine animal alert system for triggering temporary turbine shutdown when there is risk of collision with a killer whale. To develop a system that relies on active sonar twomore » critical areas must be investigated - the target strength of killer whales and the frequency content of commercially available active sonar units. PNNL studied three target strength models: a simple model, the Fourier matching model, and the Kirchoff-ray mode model. Using target strength measurements of bottlenose dolphins obtained by previous researchers and assuming killer whales share similar morphology and structure, PNNL extrapolated the target strength of an adult killer whale 7.5 m in length at a frequency of 67 kHz. To study the frequency content of a commercially available sonar unit, direct measurements of the signal transmitted by the sonar were obtained by using a hydrophone connected to a data acquisition system in both laboratory and field conditions. The measurements revealed that in addition to the primary frequency of 200 kHz, there is a secondary frequency component at 90 kHz, which is within the hearing range of killer whales. The amplitude of the 90-kHz frequency component is above the hearing threshold of killer whales but below the threshold for potential injuries.« less

Trajectory study of supercollision relaxation in highly vibrationally excited pyrazine and CO2.

PubMed

Li, Ziman; Sansom, Rebecca; Bonella, Sara; Coker, David F; Mullin, Amy S

2005-09-01

Classical trajectory calculations were performed to simulate state-resolved energy transfer experiments of highly vibrationally excited pyrazine (E(vib) = 37,900 cm(-1)) and CO(2), which were conducted using a high-resolution transient infrared absorption spectrometer. The goal here is to use classical trajectories to simulate the supercollision energy transfer pathway wherein large amounts of energy are transferred in single collisions in order to compare with experimental results. In the trajectory calculations, Newton's laws of motion are used for the molecular motion, isolated molecules are treated as collections of harmonic oscillators, and intermolecular potentials are formed by pairwise Lennard-Jones potentials. The calculations qualitatively reproduce the observed energy partitioning in the scattered CO(2) molecules and show that the relative partitioning between bath rotation and translation is dependent on the moment of inertia of the bath molecule. The simulations show that the low-frequency modes of the vibrationally excited pyrazine contribute most to the strong collisions. The majority of collisions lead to small DeltaE values and primarily involve single encounters between the energy donor and acceptor. The large DeltaE exchanges result from both single impulsive encounters and chattering collisions that involve multiple encounters.

Electron Transport and Ion Acceleration in a Low-power Cylindrical Hall Thruster

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. Smirnov; Y. Raitses; N.J. Fisch

2004-06-24

Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are therefore more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. Electron cross-field transport in a 2.6 cm miniaturized cylindrical Hall thruster (100 W power level) has been studied through the analysis of experimental data and Monte Carlo simulations of electron dynamics in the thruster channel. The numerical model takes into account elastic and inelastic electron collisions with atoms, electron-wall collisions, including secondary electron emission, and Bohm diffusion. We show that in order to explainmore » the observed discharge current, the electron anomalous collision frequency {nu}{sub B} has to be on the order of the Bohm value, {nu}{sub B} {approx} {omega}{sub c}/16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant. The plasma density peak observed at the axis of the 2.6 cm cylindrical Hall thruster is likely to be due to the convergent flux of ions, which are born in the annular part of the channel and accelerated towards the thruster axis.« less

Continuous-Time Random Walk Models of DNA Electrophoresis in a Post Array: II. Mobility and Sources of Band Broadening

PubMed Central

Olson, Daniel W.; Dutta, Sarit; Laachi, Nabil; Tian, Mingwei; Dorfman, Kevin D.

2011-01-01

Using the two-state, continuous-time random walk model, we develop expressions for the mobility and the plate height during DNA electrophoresis in an ordered post array that delineate the contributions due to (i) the random distance between collisions and (ii) the random duration of a collision. These contributions are expressed in terms of the means and variances of the underlying stochastic processes, which we evaluate from a large ensemble of Brownian dynamics simulations performed using different electric fields and molecular weights in a hexagonal array of 1 μm posts with a 3 μm center-to-center distance. If we fix the molecular weight, we find that the collision frequency governs the mobility. In contrast, the average collision duration is the most important factor for predicting the mobility as a function of DNA size at constant Péclet number. The plate height is reasonably well-described by a single post rope-over-pulley model, provided that the extension of the molecule is small. Our results only account for dispersion inside the post array and thus represent a theoretical lower bound on the plate height in an actual device. PMID:21290387

The frequency and nature of `cloud-cloud collisions' in galaxies

NASA Astrophysics Data System (ADS)

Dobbs, C. L.; Pringle, J. E.; Duarte-Cabral, A.

2015-02-01

We investigate cloud-cloud collisions and giant molecular cloud evolution in hydrodynamic simulations of isolated galaxies. The simulations include heating and cooling of the interstellar medium (ISM), self-gravity and stellar feedback. Over time-scales <5 Myr most clouds undergo no change, and mergers and splits are found to be typically two-body processes, but evolution over longer time-scales is more complex and involves a greater fraction of intercloud material. We find that mergers or collisions occur every 8-10 Myr (1/15th of an orbit) in a simulation with spiral arms, and once every 28 Myr (1/5th of an orbit) with no imposed spiral arms. Both figures are higher than expected from analytic estimates, as clouds are not uniformly distributed in the galaxy. Thus, clouds can be expected to undergo between zero and a few collisions over their lifetime. We present specific examples of cloud-cloud interactions in our results, including synthetic CO maps. We would expect cloud-cloud interactions to be observable, but find they appear to have little or no impact on the ISM. Due to a combination of the clouds' typical geometries, and moderate velocity dispersions, cloud-cloud interactions often better resemble a smaller cloud nudging a larger cloud. Our findings are consistent with the view that spiral arms make little difference to overall star formation rates in galaxies, and we see no evidence that collisions likely produce massive clusters. However, to confirm the outcome of such massive cloud collisions we ideally need higher resolution simulations.

Eccentricity fluctuation effects on elliptic flow in relativistic heavy ion collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirano, Tetsufumi; Nara, Yasushi

2009-06-15

We study effects of eccentricity fluctuations on the elliptic flow coefficient v{sub 2} at midrapidity in both Au+Au and Cu+Cu collisions at {radical}(s{sub NN})=200 GeV by using a hybrid model that combines ideal hydrodynamics for space-time evolution of the quark gluon plasma phase and a hadronic transport model for the hadronic matter. For initial conditions in hydrodynamic simulations, both the Glauber model and the color glass condensate model are employed to demonstrate the effect of initial eccentricity fluctuations originating from the nucleon position inside a colliding nucleus. The effect of eccentricity fluctuations is modest in semicentral Au+Au collisions, but significantlymore » enhances v{sub 2} in Cu+Cu collisions.« less

Collision effects of wind-power generators and other obstacles on birds.

PubMed

Drewitt, Allan L; Langston, Rowena H W

2008-01-01

There is extensive literature on avian mortality due to collision with man-made structures, including wind turbines, communication masts, tall buildings and windows, power lines, and fences. Many studies describe the consequences of bird-strike rather than address the causes, and there is little data based on long-term, standardized, and systematic assessments. Despite these limitations, it is apparent that bird-strike is a significant cause of mortality. It is therefore important to understand the effects of this mortality on bird populations. The factors which determine avian collision risk are described, including location, structural attributes, such as height and the use of lighting, weather conditions, and bird morphology and behavior. The results of incidental and more systematic observations of bird-strike due to a range of structures are presented and the implications of collision mortality for bird populations, particularly those of scarce and threatened species susceptible to collisions, are discussed. Existing measures for reducing collision mortality are described, both generally and specifically for each type of structure. It is concluded that, in some circumstances, collision mortality can adversely affect bird populations, and that greater effort is needed to derive accurate estimates of mortality levels locally, regionally, and nationally to better assess impacts on avian populations. Priority areas for future work are suggested, including further development of remote technology to monitor collisions, research into the causes of bird-strike, and the design of new, effective mitigation measures.

Effect of the fluctuating proton size on the study of the chiral magnetic effect in proton-nucleus collisions

DOE PAGES

Kharzeev, Dmitri; Tu, Zhoudunming; Zhang, Aobo; ...

2018-02-12

High energy proton-nucleus (pA) collisions provide an important constraint on the study of the chiral magnetic effect in QCD matter. Naively, in pA collisions one expects no correlation between the orientation of event plane as reconstructed from the azimuthal distribution of produced hadrons and the orientation of magnetic field. If this is the case, any charge-dependent hadron correlations can only result from the background. Nevertheless, in this paper we point out that in high multiplicity pA collisions a correlation between the magnetic field and the event plane can appear. This is because triggering on the high hadron multiplicity amounts tomore » selecting Fock components of the incident proton with a large number of partons that are expected to have a transverse size much larger than the average proton size. We introduce the effect of the fluctuating proton size in the Monte Carlo Glauber model and evaluate the resulting correlation between the magnetic field and the second-order event plane in both pA and nucleus-nucleus (AA) collisions. The fluctuating proton size is found to result in a significant correlation between magnetic field and the event plane in pA collisions, even though the magnitude of the correlation is still much smaller than in AA collisions. Here, this result opens a possibility of studying the chiral magnetic effect in small systems.« less

Effect of the fluctuating proton size on the study of the chiral magnetic effect in proton-nucleus collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kharzeev, Dmitri; Tu, Zhoudunming; Zhang, Aobo

High energy proton-nucleus (pA) collisions provide an important constraint on the study of the chiral magnetic effect in QCD matter. Naively, in pA collisions one expects no correlation between the orientation of event plane as reconstructed from the azimuthal distribution of produced hadrons and the orientation of magnetic field. If this is the case, any charge-dependent hadron correlations can only result from the background. Nevertheless, in this paper we point out that in high multiplicity pA collisions a correlation between the magnetic field and the event plane can appear. This is because triggering on the high hadron multiplicity amounts tomore » selecting Fock components of the incident proton with a large number of partons that are expected to have a transverse size much larger than the average proton size. We introduce the effect of the fluctuating proton size in the Monte Carlo Glauber model and evaluate the resulting correlation between the magnetic field and the second-order event plane in both pA and nucleus-nucleus (AA) collisions. The fluctuating proton size is found to result in a significant correlation between magnetic field and the event plane in pA collisions, even though the magnitude of the correlation is still much smaller than in AA collisions. Here, this result opens a possibility of studying the chiral magnetic effect in small systems.« less

Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

NASA Astrophysics Data System (ADS)

Baudrenghien, P.; Mastoridis, T.

2015-10-01

The high-luminosity LHC (HiLumi LHC) upgrade with planned operation from 2025 onward has a goal of achieving a tenfold increase in the number of recorded collisions thanks to a doubling of the intensity per bunch (2.2e11 protons) and a reduction of β* to 15 cm. Such an increase would significantly expedite new discoveries and exploration. To avoid detrimental effects from long-range beam-beam interactions, the half crossing angle must be increased to 295 microrad. Without bunch crabbing, this large crossing angle and small transverse beam size would result in a luminosity reduction factor of 0.3 (Piwinski angle). Therefore, crab cavities are an important component of the LHC upgrade, and will contribute strongly to achieving an increase in the number of recorded collisions. The proposed crab cavities are electromagnetic devices with a resonance in the radio frequency (rf) region of the spectrum (400.789 MHz). They cause a kick perpendicular to the direction of motion (transverse kick) to restore an effective head-on collision between the particle beams, thereby restoring the geometric factor to 0.8 [K. Oide and K. Yokoya, Phys. Rev. A 40, 315 (1989).]. Noise injected through the rf/low level rf (llrf) system could cause significant transverse emittance growth and limit luminosity lifetime. In this work, a theoretical relationship between the phase and amplitude rf noise spectrum and the transverse emittance growth rate is derived, for a hadron machine assuming zero synchrotron radiation damping and broadband rf noise, excluding infinitely narrow spectral lines. This derivation is for a single beam. Both amplitude and phase noise are investigated. The potential improvement in the presence of the transverse damper is also investigated.

Superconducting micro-resonator arrays with ideal frequency spacing

NASA Astrophysics Data System (ADS)

Liu, X.; Guo, W.; Wang, Y.; Dai, M.; Wei, L. F.; Dober, B.; McKenney, C. M.; Hilton, G. C.; Hubmayr, J.; Austermann, J. E.; Ullom, J. N.; Gao, J.; Vissers, M. R.

2017-12-01

We present a wafer trimming technique for producing superconducting micro-resonator arrays with highly uniform frequency spacing. With the light-emitting diode mapper technique demonstrated previously, we first map the measured resonance frequencies to the physical resonators. Then, we fine-tune each resonator's frequency by lithographically trimming a small length, calculated from the deviation of the measured frequency from its design value, from the interdigitated capacitor. We demonstrate this technique on a 127-resonator array made from titanium-nitride and show that the uniformity of frequency spacing is greatly improved. The array yield in terms of frequency collisions improves from 84% to 97%, while the quality factors and noise properties are unaffected. The wafer trimming technique provides an easy-to-implement tool to improve the yield and multiplexing density of large resonator arrays, which is important for various applications in photon detection and quantum computing.

Bridging the condensation-collision size gap: a direct numerical simulation of continuous droplet growth in turbulent clouds

NASA Astrophysics Data System (ADS)

Chen, Sisi; Yau, Man-Kong; Bartello, Peter; Xue, Lulin

2018-05-01

In most previous direct numerical simulation (DNS) studies on droplet growth in turbulence, condensational growth and collisional growth were treated separately. Studies in recent decades have postulated that small-scale turbulence may accelerate droplet collisions when droplets are still small when condensational growth is effective. This implies that both processes should be considered simultaneously to unveil the full history of droplet growth and rain formation. This paper introduces the first direct numerical simulation approach to explicitly study the continuous droplet growth by condensation and collisions inside an adiabatic ascending cloud parcel. Results from the condensation-only, collision-only, and condensation-collision experiments are compared to examine the contribution to the broadening of droplet size distribution (DSD) by the individual process and by the combined processes. Simulations of different turbulent intensities are conducted to investigate the impact of turbulence on each process and on the condensation-induced collisions. The results show that the condensational process promotes the collisions in a turbulent environment and reduces the collisions when in still air, indicating a positive impact of condensation on turbulent collisions. This work suggests the necessity of including both processes simultaneously when studying droplet-turbulence interaction to quantify the turbulence effect on the evolution of cloud droplet spectrum and rain formation.

Effects of lead time of verbal collision warning messages on driving behavior in connected vehicle settings.

PubMed

Wan, Jingyan; Wu, Changxu; Zhang, Yiqi

2016-09-01

Under the connected vehicle environment, vehicles will be able to exchange traffic information with roadway infrastructure and other vehicles. With such information, collision warning systems (CWSs) will be able to warn drivers with potentially hazardous situations within or out of sight and reduce collision accidents. The lead time of warning messages is a crucial factor in determining the effectiveness of CWSs in the prevention of traffic accidents. Accordingly, it is necessary to understand the effects of lead time on driving behaviors and explore the optimal lead time in various collision scenarios. The present driving simulator experiment studied the effects of controlled lead time at 16 levels (predetermined time headway from the subject vehicle to the collision location when the warning message broadcasted to a driver) on driving behaviors in various collision scenarios. Maximum effectiveness of warning messages was achieved when the controlled lead time was within the range of 5s to 8s. Specifically, the controlled lead time ranging from 4s to 8s led to the optimal safety benefit; and the controlled lead time ranging from 5s to 8s led to more gradual braking and shorter reaction time. Furthermore, a trapezoidal distribution of warning effectiveness was found by building a statistic model using curve estimation considering lead time, lifetime driving experience, and driving speed. The results indicated that the controlled lead time significantly affected driver performance. The findings have implications for the design of collision warning systems. Copyright © 2016 Elsevier Ltd and National Safety Council. All rights reserved.

Self-diffusion in a stochastically heated two-dimensional dusty plasma

NASA Astrophysics Data System (ADS)

Sheridan, T. E.

2016-09-01

Diffusion in a two-dimensional dusty plasma liquid (i.e., a Yukawa liquid) is studied experimentally. The dusty plasma liquid is heated stochastically by a surrounding three-dimensional toroidal dusty plasma gas which acts as a thermal reservoir. The measured dust velocity distribution functions are isotropic Maxwellians, giving a well-defined kinetic temperature. The mean-square displacement for dust particles is found to increase linearly with time, indicating normal diffusion. The measured diffusion coefficients increase approximately linearly with temperature. The effective collision rate is dominated by collective dust-dust interactions rather than neutral gas drag, and is comparable to the dusty-plasma frequency.

Arthroscopic Stabilization After a First-Time Dislocation: Collision Versus Contact Athletes

PubMed Central

Ranalletta, Maximiliano; Rossi, Luciano A.; Alonso Hidalgo, Ignacio; Sirio, Adrian; Puig Dubois, Julieta; Maignon, Gastón D.; Bongiovanni, Santiago L.

2017-01-01

Background: There is no universally accepted definition of “contact” or “collision” sports in the literature. The few available studies evaluating contact and collision sports consider them to be synonymous. However, athletes in collision sports purposely hit or collide with each other or with inanimate objects with greater force and frequency than in contact sports, which could jeopardize functional outcomes. Purpose: To compare the functional outcomes, return to sports, and recurrences in a series of contact and collision athletes with a first-time anterior shoulder dislocation treated using arthroscopic stabilization with suture anchors. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 56 athletes were enrolled in this study, including 22 contact athletes and 34 collision athletes. All athletes underwent arthroscopic shoulder stabilization using suture anchors. Range of motion, the Rowe score, a visual analog scale (VAS) for pain, and the Athletic Shoulder Outcome Scoring System (ASOSS) were used to assess functional outcomes. Return to sports and recurrences were also evaluated. Results: The mean age at the time of surgery was 22.2 years, and the mean follow-up was 62.4 months (range, 36-94 months). No significant difference in shoulder motion was found between preoperative and postoperative results or between the contact and collision groups. The Rowe, VAS, and ASOSS scores showed statistical improvement in both groups after surgery (P = .001). Patients in the contact group returned to sports significantly faster than those in the collision group (5.2 vs 6.9 months, respectively; P = .01). In all, 43 athletes (76.8%) returned to near-preinjury sports activity levels (≥90% recovery) after surgery: 86.4% of patients in the contact group and 70.6% in the collision group (P = .04). The total recurrence rate was 8.9%. There were 5 recurrences (14.7%) in the collision group and no recurrences in the contact group (P < .01). Conclusion: Arthroscopic stabilization for anterior instability of the shoulder is a reliable procedure with respect to shoulder function, range of motion, and postoperative return to sports in contact and collision athletes. Compared with the contact group (0%), the collision group yielded a higher failure rate (14.7%). Moreover, patients in the contact group returned significantly faster (5.2 vs 6.9 months, respectively) and to and more returned to preinjury or near-preinjury activity levels (86.4% vs 70.6% of patients, respectively) than patients in the collision group. PMID:28979919

The COLA Collision Avoidance Method

NASA Astrophysics Data System (ADS)

Assmann, K.; Berger, J.; Grothkopp, S.

2009-03-01

In the following we present a collision avoidance method named COLA. The method has been designed to predict collisions for Earth orbiting spacecraft on any orbits, including orbit changes, with other space-born objects. The point in time of a collision and the collision probability are determined. To guarantee effective processing the COLA method uses a modular design and is composed of several components which are either developed within this work or deduced from existing algorithms: A filtering module, the close approach determination, the collision detection and the collision probability calculation. A software tool which implements the COLA method has been verified using various test cases built from sample missions. This software has been implemented in the C++ programming language and serves as a universal collision detection tool at LSE Space Engineering & Operations AG.

Effective collision strengths for the electron impact excitation of Mg

NASA Astrophysics Data System (ADS)

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

2008-05-01

Electron impact excitation collision strengths for fine structure transitions of Mg,have been determined by a Breit-Pauli R-matrix calculation. The target states are represented by configuration interaction wavefunctions and consist of the 19 lowest LS states, having configurations 2s^22p^4, 2s2p^5, 2p^6, 2s^22p^33s and 2s^22p^33p. These target states give rise to 37 fine structure levels and 666 possible transitions. The effective collision strengths are calculated by averaging the electron collision strengths over a Maxwellian distribution of electron velocities. Effective collision strengths for transitions between the fine structure levels are given for electron temperatures in the range 10Te(K) = 3.0 - 7.0. Results are compared with the previous R-matrix calculation of Butler & Zeippen (AASS, 1994) and the recent Distorted Wave evaluations of Bhatia, Landi & Eissner (ADNDT, 2006).

Crystal nucleation initiated by transient ion-surface interactions at aerosol interfaces

PubMed Central

Davis, Ryan D.; Tolbert, Margaret A.

2017-01-01

Particle collisions are a common occurrence in the atmosphere, but no empirical observations exist to fully predict the potential effects of these collisions on air quality and climate projections. The current consensus of heterogeneous crystal nucleation pathways relevant to the atmosphere dictates that collisions with amorphous particles have no effect on the crystallization relative humidity (RH) of aqueous inorganic aerosols because there is no stabilizing ion-surface interaction to facilitate the formation of crystal nuclei. In contrast to this view of heterogeneous nucleation, we report laboratory observations demonstrating that collisions with hydrophobic amorphous organic aerosols induced crystallization of aqueous inorganic microdroplets at high RH, the effect of which was correlated with destabilizing water-mediated ion-specific surface interactions. These same organic aerosols did not induce crystallization once internally mixed in the droplet, pointing toward a previously unconsidered transient ion-specific crystal nucleation pathway that can promote aerosol crystallization via particle collisions. PMID:28776032

Crystal nucleation initiated by transient ion-surface interactions at aerosol interfaces.

PubMed

Davis, Ryan D; Tolbert, Margaret A

2017-07-01

Particle collisions are a common occurrence in the atmosphere, but no empirical observations exist to fully predict the potential effects of these collisions on air quality and climate projections. The current consensus of heterogeneous crystal nucleation pathways relevant to the atmosphere dictates that collisions with amorphous particles have no effect on the crystallization relative humidity (RH) of aqueous inorganic aerosols because there is no stabilizing ion-surface interaction to facilitate the formation of crystal nuclei. In contrast to this view of heterogeneous nucleation, we report laboratory observations demonstrating that collisions with hydrophobic amorphous organic aerosols induced crystallization of aqueous inorganic microdroplets at high RH, the effect of which was correlated with destabilizing water-mediated ion-specific surface interactions. These same organic aerosols did not induce crystallization once internally mixed in the droplet, pointing toward a previously unconsidered transient ion-specific crystal nucleation pathway that can promote aerosol crystallization via particle collisions.

Features of HF Radio Wave Attenuation in the Midlatitude Ionosphere Near the Skip Zone Boundary

NASA Astrophysics Data System (ADS)

Denisenko, P. F.; Skazik, A. I.

2017-06-01

We briefly describe the history of studying the decameter radio wave attenuation by different methods in the midlatitude ionosphere. A new method of estimating the attenuation of HF radio waves in the ionospheric F region near the skip zone boundary is presented. This method is based on an analysis of the time structure of the interference field generated by highly stable monochromatic X-mode radio waves at the observation point. The main parameter is the effective electron collision frequency νeff, which allows for all energy losses in the form of equivalent heat loss. The frequency νeff is estimated by matching the assumed (model) and the experimentally observed structures. Model calculations are performed using the geometrical-optics approximation. The spatial attenuation caused by the influence of the medium-scale traveling ionospheric disturbances is taken into account. Spherical shape of the ionosphere and the Earth's magnetic field are roughly allowed for. The results of recording of the level of signals from the RWM (Moscow) station at a frequency of 9.996 MHz at point Rostov are used.

Numerical Evaluation of Parameter Correlation in the Hartmann-Tran Line Profile

NASA Astrophysics Data System (ADS)

Adkins, Erin M.; Reed, Zachary; Hodges, Joseph T.

2017-06-01

The partially correlated quadratic, speed-dependent hard-collision profile (pCqSDHCP), for simplicity referred to as the Hartmann-Tran profile (HTP), has been recommended as a generalized lineshape for high resolution spectroscopy. The HTP parameterizes complex collisional effects such as Dicke narrowing, speed dependent narrowing, and correlations between velocity-changing and dephasing collisions, while also simplifying to simpler profiles that are widely used, such as the Voigt profile. As advanced lineshape profiles are adopted by more researchers, it is important to understand the limitations that data quality has on the ability to retrieve physically meaningful parameters using sophisticated lineshapes that are fit to spectra of finite signal-to-noise ratio. In this work, spectra were simulated using the HITRAN Application Programming Interface (HAPI) across a full range of line parameters. Simulated spectra were evaluated to quantify the precision with which fitted lineshape parameters can be determined at a given signal-to-noise ratio, focusing on the numerical correlation between the retrieved Dicke narrowing frequency and the velocity-changing and dephasing collisions correlation parameter. Tran, H., N. Ngo, and J.-M. Hartmann, Journal of Quantitative Spectroscopy and Radiative Transfer 2013. 129: p. 89-100. Tennyson, et al., Pure Appl. Chem. 2014, 86: p. 1931-1943. Kochanov, R.V., et al., Journal of Quantitative Spectroscopy and Radiative Transfer 2016. 177: p. 15-30. Tran, H., N. Ngo, and J.-M. Hartmann, Journal of Quantitative Spectroscopy and Radiative Transfer 2013. 129: p. 199-203.

The method of impedance transformation for electromagnetic waves propagating in one-dimension plasma photonic crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Jingfeng; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn; Gao, Ruilin

2016-08-15

This study focuses on the transmission of normal-incidence electromagnetic waves in one-dimensional plasma photonic crystals. Using the Maxwell's equations in a medium, a method that is based on the concept of impendence is employed to perform the simulation. The accuracy of the method was evaluated by simulating a one-layer plasma and conventional photonic crystal. In frequency-domain, the transmission and reflection coefficients in the unmagnetized plasma photonic crystal were calculated, and the influence factors on plasma photonic crystals including dielectric constants of dielectric, spatial period, filling factor, plasma frequency, and collision frequency were studied.

Effect of an anisotropic escape mechanism on elliptic flow in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Jaiswal, Amaresh; Bhaduri, Partha Pratim

2018-04-01

We study the effect of an anisotropic escape mechanism on elliptic flow in relativistic heavy-ion collisions. We use the Glauber model to generate initial conditions and ignore hydrodynamic expansion in the transverse direction. We employ the Beer-Lambert law to allow for the transmittance of produced hadrons in the medium and calculate the anisotropy generated due to the suppression of particles traversing through the medium. To separate non-flow contribution due to surface bias effects, we ignore hydrodynamic expansion in the transverse direction and consider purely longitudinal boost-invariant expansion. We calculate the transverse momentum dependence of elliptic flow, generated from an anisotropic escape mechanism due to surface bias effects, for various centralities in √{sN N}=200 GeV Au +Au collisions at the Relativistic Heavy Ion Collider and √{sN N}=2.76 TeV Pb +Pb collisions at the Large Hadron Collider. We find that the surface bias effects make a sizable contribution to the total elliptic flow observed in heavy-ion collisions, indicating that the viscosity of the QCD matter extracted from hydrodynamic simulations may be underestimated.

Electromagnetic drift waves dispersion for arbitrarily collisional plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Wonjae, E-mail: wol023@ucsd.edu; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu; Angus, J. R.

2015-07-15

The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionlessmore » and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.« less

Bi-stable frequency up-conversion piezoelectric energy harvester driven by non-contact magnetic repulsion

NASA Astrophysics Data System (ADS)

Tang, Q. C.; Yang, Y. L.; Li, Xinxin

2011-12-01

This paper presents miniaturized energy harvesters, where the frequency up-conversion technique is used to improve the bandwidth of vibration energy harvesters. The proposed and developed miniature piezoelectric energy harvester utilizes magnetic repulsion forces to achieve non-contact frequency up-conversion, thereby avoiding mechanical collision and wear for long-term working durability. A pair of piezoelectric resonant cantilevers is micro-fabricated to generate electric power. A simplified model involving linear oscillators and magnetic interaction is deployed to demonstrate the feasibility of the device design. A bench-top harvester has been fabricated and characterized, resulting in average power generation of over 10 µW within a broad frequency range of 10-22 Hz under 1g acceleration.

Thermal Effects for Quark and Gluon Distributions in Heavy-Ion Collisions at Nica

NASA Astrophysics Data System (ADS)

Lykasov, G. I.; Sissakian, A. N.; Sorin, A. S.; Teryaev, O. V.

2011-10-01

In-medium effects for distributions of quarks and gluons in central A+A collisions are considered. We suggest a duality principle, which means similarity of thermal spectra of hadrons produced in heavy-ion collisions and inclusive spectra which can be obtained within the dynamic quantum scattering theory. Within the suggested approach we show that the mean square of the transverse momentum for these partons grows and then saturates when the initial energy increases. It leads to the energy dependence of hadron transverse mass spectra which is similar to that observed in heavy ion collisions.

Survival of the impactor during hypervelocity collisions - II. An analogue for high-porosity targets

NASA Astrophysics Data System (ADS)

Avdellidou, C.; Price, M. C.; Delbo, M.; Cole, M. J.

2017-01-01

We investigated how a target's porosity affects the outcome of a collision, with respect to the impactor's fate. Laboratory impact experiments using peridot projectiles were performed at a speed range between 0.3 and 3.0 km s-1, on to high-porosity water-ice (40 per cent) and fine-grained calcium carbonate (70 per cent) targets. We report that the amount of implanted material in the target body increases with increasing target's porosity, while the size frequency distribution of the projectile's ejecta fragments becomes steeper. A supplementary Raman study showed no sign of change of the Raman spectra of the recovered olivine projectile fragments indicate minimal physical change.

Collisional redistribution of radiation. III - The equation of motion for the correlation function and the scattered spectrum

NASA Technical Reports Server (NTRS)

Burnett, K.; Cooper, J.

1980-01-01

Computations were made of the scattering of monochromatic radiation by a degenerate atom in the binary-collision approximation for field strengths whose products of the Rabi frequency for atomic transition and the duration of a strong collision are much less than 1. An expression of motion for the correlation function is derived which does not exclude the region where thermal correlations may be neglected; the equation is valid outside the quantum-regression regime, and has a straightforward solution for practical cases. Solutions for the weak-field linear response regime are presented in terms of generalized absorption and emission profiles which depend on the indices of the atomic multipoles.

Intersection collision avoidance using ITS countermeasures. Task 9, Intersection collision avoidance system performance guidelines

DOT National Transportation Integrated Search

2000-09-01

Phase III of the Intersection Collision Avoidance Using ITS Countermeasures program developed testbed systems, implemented the systems on a vehicle, and performed testing to determine the potential effectiveness of this system in preventing intersect...

A fully-implicit Particle-In-Cell Monte Carlo Collision code for the simulation of inductively coupled plasmas

NASA Astrophysics Data System (ADS)

Mattei, S.; Nishida, K.; Onai, M.; Lettry, J.; Tran, M. Q.; Hatayama, A.

2017-12-01

We present a fully-implicit electromagnetic Particle-In-Cell Monte Carlo collision code, called NINJA, written for the simulation of inductively coupled plasmas. NINJA employs a kinetic enslaved Jacobian-Free Newton Krylov method to solve self-consistently the interaction between the electromagnetic field generated by the radio-frequency coil and the plasma response. The simulated plasma includes a kinetic description of charged and neutral species as well as the collision processes between them. The algorithm allows simulations with cell sizes much larger than the Debye length and time steps in excess of the Courant-Friedrichs-Lewy condition whilst preserving the conservation of the total energy. The code is applied to the simulation of the plasma discharge of the Linac4 H- ion source at CERN. Simulation results of plasma density, temperature and EEDF are discussed and compared with optical emission spectroscopy measurements. A systematic study of the energy conservation as a function of the numerical parameters is presented.

Influence of local-field corrections on Thomson scattering in collision-dominated two-component plasmas.

PubMed

Fortmann, Carsten; Wierling, August; Röpke, Gerd

2010-02-01

The dynamic structure factor, which determines the Thomson scattering spectrum, is calculated via an extended Mermin approach. It incorporates the dynamical collision frequency as well as the local-field correction factor. This allows to study systematically the impact of electron-ion collisions as well as electron-electron correlations due to degeneracy and short-range interaction on the characteristics of the Thomson scattering signal. As such, the plasmon dispersion and damping width is calculated for a two-component plasma, where the electron subsystem is completely degenerate. Strong deviations of the plasmon resonance position due to the electron-electron correlations are observed at increasing Brueckner parameters r(s). These results are of paramount importance for the interpretation of collective Thomson scattering spectra, as the determination of the free electron density from the plasmon resonance position requires a precise theory of the plasmon dispersion. Implications due to different approximations for the electron-electron correlation, i.e., different forms of the one-component local-field correction, are discussed.

Spectral shapes of rovibrational lines of CO broadened by He, Ar, Kr and SF6: A test case of the Hartmann-Tran profile

NASA Astrophysics Data System (ADS)

Ngo, N. H.; Lin, H.; Hodges, J. T.; Tran, H.

2017-12-01

High signal-to-noise ratio spectra of the (3-0) band P(1) and P(17) lines of CO broadened by He, Ar, Kr and SF6 were measured with a frequency-stabilized cavity ring-down spectroscopy system. For each collision-partner and both lines, multiple spectra were measured over pressures spanning nearly three decades up to 130 kPa. These data were analyzed with a multispectrum fitting procedure. Line shapes were modeled using the Hartmann-Tran (HT) profile with first-order line mixing as well as several other simplified profiles. The results show that for all considered collision partners (with the exception of SF6), the HT profile captures the measured line shapes with maximum absolute residuals that are within 0.1% of the peak absorption. In the case of SF6, which is the heaviest perturber investigated here, the maximum residuals for the HT profile are twice as large as for the other collision partners.

Intermolecular dynamics of substitued benzene and cyclohexane liquids, studied by femtosecond nonlinear-optical polarization spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Y.J.; Castner, E.W. Jr.

Femtosecond time-resolved optical-heterodyne detected Raman-induced Kerr effect spectroscopy (OHD-RIKES) is shown to be a powerful and comprehensive tool for studying the intermolecular dynamics occurring in liquids. The observed dynamics include both the underdamped or coherent inertial motions, and the longer time scale diffusive relaxation. The inertial dynamics include phonon-like intermolecular vibrations, intermolecular collisions, and librational caging motions. Data are presented and analyzed for a series of five liquids: cyclohexane, methylcyclohexane, toluene, benzyl alcohol, and benzonitrile, listed in order of increasing polarity. We explore the effects of aromaticity (e.g., methylcyclohexane vs toluene), symmetry reduction (cyclohexane vs methylcyclohexane), and substitution effects (e.g.,more » substituted benzene series) on the ultrafast intermolecular dynamics, for a group of molecular liquids of similar size and volume. We analyze the intermolecular dynamics in both the time and frequency domains by means of Fourier transformations. When Fourier-transformed into the frequency domain, the OHD-RIKES ultrafast transients of the intermolecular dynamics can be directly compared with the frequency domain spectra obtained from the far-infrared absorption and depolarized Raman techniques. This is done using the Gaussian librational caging model of Lynden-Bell and Steele, which results in a power-law scaling relation between dipole and polarizability time correlation functions. 122 refs., 7 figs., 7 tabs.« less

Effects of the major sudden stratospheric warming event of 2009 on the subionospheric very low frequency/low frequency radio signals

NASA Astrophysics Data System (ADS)

Pal, S.; Hobara, Y.; Chakrabarti, S. K.; Schnoor, P. W.

2017-07-01

This paper presents effects of the major sudden stratospheric warming (SSW) event of 2009 on the subionospheric very low frequency/low frequency (VLF/LF) radio signals propagating in the Earth-ionosphere waveguide. Signal amplitudes from four transmitters received by VLF/LF radio networks of Germany and Japan corresponding to the major SSW event are investigated for possible anomalies and atmospheric influence on the high- to middle-latitude ionosphere. Significant anomalous increase or decrease of nighttime and daytime amplitudes of VLF/LF signals by ˜3-5 dB during the SSW event have been found for all propagation paths associated with stratospheric temperature rise at 10 hPa level. Increase or decrease in VLF/LF amplitudes during daytime and nighttime is actually due to the modification of the lower ionospheric boundary conditions in terms of electron density and electron-neutral collision frequency profiles and associated modal interference effects between the different propagating waveguide modes during the SSW period. TIMED/SABER mission data are also used to investigate the upper mesospheric conditions over the VLF/LF propagation path during the same time period. We observe a decrease in neutral temperature and an increase in pressure at the height of 75-80 km around the peak time of the event. VLF/LF anomalies are correlated and in phase with the stratospheric temperature and mesospheric pressure variation, while minimum of mesospheric cooling shows a 2-3 day delay with maximum VLF/LF anomalies. Simulations of VLF/LF diurnal variation are performed using the well-known Long Wave Propagating Capability (LWPC) code within the Earth-ionosphere waveguide to explain the VLF/LF anomalies qualitatively.

Incoherent radar spectra in the auroral ionosphere in the presence of a large electric field: The effect of O+-O+ Coulomb collisions

NASA Astrophysics Data System (ADS)

Barghouthi, I. A.

2005-06-01

We have used Monte Carlo simulations of O+ velocity distributions in the high latitude F- region to improve the calculation of incoherent radar spectra in auroral ionosphere. The Monte Carlo simulation includes ionneutral, O+-O collisions (resonant charge exchange and polarization interaction) as well as O+-O+ Coulomb self-collisions. At high altitudes, atomic oxygen O and atomic oxygen ion O+ dominate the composition of the auroral ionosphere and consequently, the influence of O+-O+ Coulomb collisions becomes significant. In this study we consider the effect of O+-O+ Coulomb collisions on the incoherent radar spectra in the presence of large electric field (100 mVm-1). As altitude increases (i.e. the ion-to-neutral density ratio increases) the role of O+-O+ Coulomb self-collisions becomes significant, therefore, the one-dimensional, 1-D, O+ ion velocity distribution function becomes more Maxwellian and the features of the radar spectrum corresponding to non-Maxwellian ion velocity distribution (e.g. baby bottle and triple hump shapes) evolve to Maxwellian ion velocity distribution (single and double hump shapes). Therefore, O+-O+ Coulomb self-collisions act to isotropize the 1-D O+ velocity distribution by transferring thermal energy from the perpendicular direction to the parallel direction, however the convection electric field acts to drive the O+ ions away from equilibrium and consequently, non-Maxwellian O+ ion velocity distributions appeared. Therefore, neglecting O+-O+ Coulomb self-collisions overestimates the effect of convection electric field.

Navigational Traffic Conflict Technique: A Proactive Approach to Quantitative Measurement of Collision Risks in Port Waters

NASA Astrophysics Data System (ADS)

Debnath, Ashim Kumar; Chin, Hoong Chor

Navigational safety analysis relying on collision statistics is often hampered because of the low number of observations. A promising alternative approach that overcomes this problem is proposed in this paper. By analyzing critical vessel interactions this approach proactively measures collision risk in port waters. The proposed method is illustrated for quantitative measurement of collision risks in Singapore port fairways, and validated by examining correlations between the measured risks with those perceived by pilots. This method is an ethically appealing alternative to the collision-based analysis for fast, reliable and effective safety assessment, thus possessing great potential for managing collision risks in port waters.

Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

NASA Astrophysics Data System (ADS)

Singh, S. C.; Fallon, C.; Hayden, P.; Mujawar, M.; Yeates, P.; Costello, J. T.

2014-09-01

Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

Propagation velocity of Alfven wave packets in a dissipative plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amagishi, Y.; Nakagawa, H.; Tanaka, M.

1994-09-01

We have experimentally studied the behavior of Alfven wave packets in a dissipative plasma due to ion--neutral-atom collisions. It is urged that the central frequency of the packet is observed to gradually decrease with traveling distance in the absorption range of frequencies because of a differential damping among the Fourier components, and that the measured average velocity of its peak amplitude is not accounted for by the conventional group velocity, but by the prediction derived by Tanaka, Fujiwara, and Ikegami [Phys. Rev. A 34, 4851 (1986)]. Furthermore, when the initial central frequency is close to the critical frequency in themore » anomalous dispersion, the wave packet apparently collapses when traveling along the magnetic field; however, we have found that it is decomposed into another two wave packets with the central frequencies being higher or lower than the critical frequency.« less

Propagation velocity of Alfvén wave packets in a dissipative plasma

NASA Astrophysics Data System (ADS)

Amagishi, Yoshimitsu; Nakagawa, Hiroyuki; Tanaka, Masayoshi

1994-09-01

We have experimentally studied the behavior of Alfvén wave packets in a dissipative plasma due to ion-neutral-atom collisions. It is urged that the central frequency of the packet is observed to gradually decrease with traveling distance in the absorption range of frequencies because of a differential damping among the Fourier components, and that the measured average velocity of its peak amplitude is not accounted for by the conventional group velocity, but by the prediction derived by Tanaka, Fujiwara, and Ikegami [Phys. Rev. A 34, 4851 (1986)]. Furthermore, when the initial central frequency is close to the critical frequency in the anomalous dispersion, the wave packet apparently collapses when traveling along the magnetic field; however, we have found that it is decomposed into another two wave packets with the central frequencies being higher or lower than the critical frequency.

Effect of perception irregularity on chain-reaction crash in low visibility

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

2015-06-01

We present the dynamic model of the chain-reaction crash to take into account the irregularity of the perception-reaction time. When a driver brakes according to taillights of the forward vehicle, the perception-reaction time varies from driver to driver. We study the effect of the perception irregularity on the chain-reaction crash (multiple-vehicle collision) in low-visibility condition. The first crash may induce more collisions. We investigate how the first collision induces the chain-reaction crash numerically. We derive, analytically, the transition points and the region maps for the chain-reaction crash in traffic flow of vehicles with irregular perception times. We clarify the effect of the perception irregularity on the multiple-vehicle collision.

Mass and Size Frequency Distribution of the Impact Debris from Disruption of Chondritic Meteorites

NASA Technical Reports Server (NTRS)

VanVeghten, T. W.; Flynn, G. J.; Durda, D. D.; Hart, S.; Asphaug, E.

2003-01-01

Since direct observation of the collision of asteroids in space is not always convenient for earthbound observers, we have undertaken simulations of these collisions using the NASA Ames Vertical Gun Range (AVGR). To simulate the collision of asteroids in space, and aluminum projectiles with velocities ranging from approx.1 to approx.6 km/sec were fired at 70g to approx.200 g fragments of chondritic meteorites. The target meteorite was placed in an evacuated chamber at the AVGR. Detectors, usually four, were set up around the target meteorite. These detectors consisted of aerogel and aluminum foil of varying thickness. The aerogel's purpose was to catch debris after the collision, and the aluminum foil.s purpose was to show the size of the debris particles through the size of the holes in the aluminum foil. Outside the chamber, a camera was set up to record high-speed film of the collision. This camera recorded at either 500 frames per second or 1000 frames per second. Three different types of targets were used for these tests. The first were actual meteorites, which varied in mineralogical composition, density, and porosity. The second type of target was a Hawaiian basalt, consisting of olivine phenocrysts in a porous matrix, which we thought might be similar to the chondritic meteorites, thus providing data for comparison. The final type was made out of Styrofoam. The Styrofoam was thought to simulate very low-density asteroids and comets.

D -meson production in p -Pb collisions at √{sNN}=5.02 TeV and in p p collisions at √{s }=7 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Albuquerque, D. S. D.; 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.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; 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.; Beltran, L. G. 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.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Bonora, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Cabala, J.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; 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.; Crkovska, J.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; de Souza, R. D.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; di Ruzza, B.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Gallio, M.; Galvan, C. D.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, A. S.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosa, F.; Grosse-Oetringhaus, J. F.; Grosso, R.; Gruber, L.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Hellbär, E.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Horak, D.; Hosokawa, R.; Hristov, P.; Hughes, C.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Incani, E.; Ippolitov, M.; Irfan, M.; Isakov, V.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacak, B.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Khatun, A.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, J.; 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.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lapidus, K.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, S.; Lehas, F.; Lehner, S.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; 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.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lupi, M.; Lutz, T. H.; 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.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Mhlanga, S.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Mohler, C.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Münning, K.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Negrao de Oliveira, R. A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Oravec, M.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, D.; Pagano, P.; Paić, G.; Pal, S. K.; Palni, P.; Pan, J.; Pandey, A. K.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Peng, X.; Pereira da Costa, H.; Peresunko, D.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Poppenborg, H.; 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.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Ravasenga, I.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; 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.; Saarinen, S.; Sadhu, S.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarkar, N.; Sarma, P.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schmidt, M.; Schuchmann, S.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Sheikh, A. I.; Shigaki, K.; Shou, Q.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singhal, V.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stankus, P.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Sumowidagdo, S.; Szabo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thakur, D.; Thomas, D.; Tieulent, R.; Tikhonov, A.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vala, M.; Valencia Palomo, L.; 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.; Vauthier, A.; Vázquez Doce, O.; Vechernin, V.; Veen, A. M.; Velure, A.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Vickovic, L.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; 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.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Willems, G. A.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yalcin, S.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

2016-11-01

Background: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton-proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton-nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclear-matter effects. Most of these effects are expected to modify open-charm production at low transverse momenta (pT) and, so far, no measurement of D -meson production down to zero transverse momentum was available at mid-rapidity at the energies attained at the CERN Large Hadron Collider (LHC). Purpose: The measurements of the production cross sections of promptly produced charmed mesons in p -Pb collisions at the LHC down to pT=0 and the comparison to the results from p p interactions are aimed at the assessment of cold-nuclear-matter effects on open-charm production, which is crucial for the interpretation of the results from Pb-Pb collisions. Methods: The prompt charmed mesons D0,D+,D*+, and Ds+ were measured at mid-rapidity in p -Pb collisions at a center-of-mass energy per nucleon pair √{sN N}=5.02 TeV with the ALICE detector at the LHC. D mesons were reconstructed from their decays D0→K-π+ ,D+→K-π+π+, D*+→D0π+ ,Ds+→ϕ π+→K-K+π+ , and their charge conjugates, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. In addition, the prompt D0 production cross section was measured in p p collisions at √{s }=7 TeV and p -Pb collisions at √{sN N}=5.02 TeV down to pT=0 using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the D0 decay vertex. Results: The production cross section in p p collisions is described within uncertainties by different implementations of pQCD calculations down to pT=0 . This allowed also a determination of the total c c ¯ production cross section in p p collisions, which is more precise than previous ALICE measurements because it is not affected by uncertainties owing to the extrapolation to pT=0 . The nuclear modification factor Rp Pb(pT) , defined as the ratio of the pT-differential D meson cross section in p -Pb collisions and that in p p collisions scaled by the mass number of the Pb nucleus, was calculated for the four D -meson species and found to be compatible with unity within uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium. Conclusions: These measurements add experimental evidence that the modification of the D -meson transverse momentum distributions observed in Pb-Pb collisions with respect to p p interactions is due to strong final-state effects induced by the interactions of the charm quarks with the hot and dense partonic medium created in ultrarelativistic heavy-ion collisions. The current precision of the measurement does not allow us to draw conclusions on the role of the different cold-nuclear-matter effects and on the possible presence of additional hot-medium effects in p -Pb collisions. However, the analysis technique without decay-vertex reconstruction, applied on future larger data samples, should provide access to the physics-rich range down to pT=0 .

D -meson production in p -Pb collisions at s NN = 5.02 TeV and in p p collisions at s = 7 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Bmore » ackground: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton-proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton-nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclear-matter effects. Most of these effects are expected to modify open-charm production at low transverse momenta (pT) and, so far, no measurement of D-meson production down to zero transverse momentum was available at mid-rapidity at the energies attained at the CERN Large Hadron Collider (LHC). Purpose: The measurements of the production cross sections of promptly produced charmed mesons in p-Pb collisions at the LHC down to pT=0 and the comparison to the results from pp interactions are aimed at the assessment of cold-nuclear-matter effects on open-charm production, which is crucial for the interpretation of the results from Pb-Pb collisions. Methods: The prompt charmed mesons D 0,D +,D⁺+, and D S + were measured at mid-rapidity in p-Pb collisions at a center-of-mass energy per nucleon pair s NN =5.02 TeV with the ALICE detector at the LHC. D mesons were reconstructed from their decays D0→K-π+,D+→K-π+π+, D⁺+→D0π+,Ds+→φπ+→K-K+π+, and their charge conjugates, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. In addition, the prompt D0 production cross section was measured in pp collisions at s NN =7 TeV and p-Pb collisions at s NN =5.02 TeV down to pT=0 using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the D0 decay vertex. Results: The production cross section in pp collisions is described within uncertainties by different implementations of pQCD calculations down to pT=0. This allowed also a determination of the total cc production cross section in pp collisions, which is more precise than previous ALICE measurements because it is not affected by uncertainties owing to the extrapolation to pT=0. The nuclear modification factor RpPb(pT), defined as the ratio of the pT-differential D meson cross section in p-Pb collisions and that in pp collisions scaled by the mass number of the Pb nucleus, was calculated for the four D-meson species and found to be compatible with unity within uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium. Conclusions: These measurements add experimental evidence that the modification of the D-meson transverse momentum distributions observed in Pb-Pb collisions with respect to pp interactions is due to strong final-state effects induced by the interactions of the charm quarks with the hot and dense partonic medium created in ultrarelativistic heavy-ion collisions. The current precision of the measurement does not allow us to draw conclusions on the role of the different cold-nuclear-matter effects and on the possible presence of additional hot-medium effects in p-Pb collisions. However, the analysis technique without decay-vertex reconstruction, applied on future larger data samples, should provide access to the physics-rich range down to pT=0.« less

D -meson production in p -Pb collisions at s NN = 5.02 TeV and in p p collisions at s = 7 TeV

DOE PAGES

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

2016-11-23

Bmore » ackground: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton-proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton-nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclear-matter effects. Most of these effects are expected to modify open-charm production at low transverse momenta (pT) and, so far, no measurement of D-meson production down to zero transverse momentum was available at mid-rapidity at the energies attained at the CERN Large Hadron Collider (LHC). Purpose: The measurements of the production cross sections of promptly produced charmed mesons in p-Pb collisions at the LHC down to pT=0 and the comparison to the results from pp interactions are aimed at the assessment of cold-nuclear-matter effects on open-charm production, which is crucial for the interpretation of the results from Pb-Pb collisions. Methods: The prompt charmed mesons D 0,D +,D⁺+, and D S + were measured at mid-rapidity in p-Pb collisions at a center-of-mass energy per nucleon pair s NN =5.02 TeV with the ALICE detector at the LHC. D mesons were reconstructed from their decays D0→K-π+,D+→K-π+π+, D⁺+→D0π+,Ds+→φπ+→K-K+π+, and their charge conjugates, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. In addition, the prompt D0 production cross section was measured in pp collisions at s NN =7 TeV and p-Pb collisions at s NN =5.02 TeV down to pT=0 using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the D0 decay vertex. Results: The production cross section in pp collisions is described within uncertainties by different implementations of pQCD calculations down to pT=0. This allowed also a determination of the total cc production cross section in pp collisions, which is more precise than previous ALICE measurements because it is not affected by uncertainties owing to the extrapolation to pT=0. The nuclear modification factor RpPb(pT), defined as the ratio of the pT-differential D meson cross section in p-Pb collisions and that in pp collisions scaled by the mass number of the Pb nucleus, was calculated for the four D-meson species and found to be compatible with unity within uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium. Conclusions: These measurements add experimental evidence that the modification of the D-meson transverse momentum distributions observed in Pb-Pb collisions with respect to pp interactions is due to strong final-state effects induced by the interactions of the charm quarks with the hot and dense partonic medium created in ultrarelativistic heavy-ion collisions. The current precision of the measurement does not allow us to draw conclusions on the role of the different cold-nuclear-matter effects and on the possible presence of additional hot-medium effects in p-Pb collisions. However, the analysis technique without decay-vertex reconstruction, applied on future larger data samples, should provide access to the physics-rich range down to pT=0.« less

Collinear collision chemistry. II. Energy disposition in reactive collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahan, B.H.

1974-06-01

A model describing the mechanics of collinear atom-diatom collisions and previously reported by the author is extended to describe reactive collisions. The model indicates the effects of such factors as the mass distribution and potential energy barriers and wells on the reaction probability and on the distribution of energy among the modes of motion of the products. Simple geometry and trigonometry are sufficient to solve the model.

Evaluation of Intersection Collision Warning Systems in Minnesota

DOT National Transportation Integrated Search

2017-10-01

The Minnesota Department of Transportation (MnDOT) is investing significant resources in intersection collision warning systems (ICWS) based on early indications of effectiveness. However, the effectiveness is not well documented, and negative change...

LS Channel Estimation and Signal Separation for UHF RFID Tag Collision Recovery on the Physical Layer.

PubMed

Duan, Hanjun; Wu, Haifeng; Zeng, Yu; Chen, Yuebin

2016-03-26

In a passive ultra-high frequency (UHF) radio-frequency identification (RFID) system, tag collision is generally resolved on a medium access control (MAC) layer. However, some of collided tag signals could be recovered on a physical (PHY) layer and, thus, enhance the identification efficiency of the RFID system. For the recovery on the PHY layer, channel estimation is a critical issue. Good channel estimation will help to recover the collided signals. Existing channel estimates work well for two collided tags. When the number of collided tags is beyond two, however, the existing estimates have more estimation errors. In this paper, we propose a novel channel estimate for the UHF RFID system. It adopts an orthogonal matrix based on the information of preambles which is known for a reader and applies a minimum-mean-square-error (MMSE) criterion to estimate channels. From the estimated channel, we could accurately separate the collided signals and recover them. By means of numerical results, we show that the proposed estimate has lower estimation errors and higher separation efficiency than the existing estimates.

Dipolar collisions of ultracold 23Na87Rb molecules.

NASA Astrophysics Data System (ADS)

Guo, Mingyang; Ye, Xin; He, Junyu; Quéméner, Goulven; González-Martínez, Maykel; Dulieu, Olivier; Wang, Dajun

2017-04-01

Although ultracold polar molecules have long been proposed as a primary candidate for investigating dipolar many body physics, many of their basic properties, like their collisions in external electric fields, are still largely unknown. In fact, despite the successful production of several new ultracold molecular species in the last two years, so far the only available dipolar collision data is still from JILA's fermionic 40K87Rb experiment in 2010. In this talk, we will describe our investigation on dipolar collisions of ultracold bosonic and chemically stable 23Na87Rb molecules which possess a large permanent electric dipole moment. With a moderate electric field, an effective dipole moment large enough to strongly couple higher partial waves into the collisions can be achieved. We will report the influence of this effect on the molecular collisions observed in our experiment. Our theoretical model for understanding these observations will also be presented. This work is supported by the Hong Kong RGC CUHK404712 and the ANR/RGC Joint Research Scheme ACUHK403/13.

Charmonium production in pPb and PbPb collisions at 5.02 TeV with CMS

NASA Astrophysics Data System (ADS)

Martín Blanco, Javier

2018-02-01

Charmonium states, such as the J/ψ and ψ(2S) mesons, are excellent probes of the deconfined state of matter, the Quark-Gluon Plasma (QGP) created in heavy ion collisions. In addition, the measurements in pPb collisions allow to study the cold nuclear matter effects, being crucial to disentangle these from the QGP-related effects in PbPb collisions. In this talk the new nuclear modification factor RAA of prompt and nonprompt J/ψ in PbPb collisions at = 5.02 TeV were presented over a wide kinematic range (3 < pT < 50 GeV/c, |y| < 2.4), and fine event-centrality intervals. The results were compared to those at 2.76 TeV over a similar kinematic range. In addition, new prompt ψ(2S) RAA results at 5.02 TeV were reported. Finally the final prompt and nonprompt J/ψ results, as well as preliminary ψ(2S) results, in pPb collisions at 5.02 TeV, were discussed.

Optical antenna enhanced spontaneous emission

PubMed Central

Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C.

2015-01-01

Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼200 THz optical frequency show a spontaneous emission intensity enhancement of 35× corresponding to a spontaneous emission rate speedup ∼115×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼2,500× spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d2. Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = qω|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

Optical antenna enhanced spontaneous emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eggleston, Michael S.; Messer, Kevin; Zhang, Liming

Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ~200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ~115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ~2,500 × spontaneous emission speedup at d ~10 nm, proportional to 1/d 2. Unfortunately, at dmore » < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Additionally, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.« less

Optical antenna enhanced spontaneous emission.

PubMed

Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C

2015-02-10

Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼ 200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ∼ 115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼ 2,500 × spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d(2). Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.

Optical antenna enhanced spontaneous emission

DOE PAGES

Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; ...

2015-01-26

Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ~200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ~115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ~2,500 × spontaneous emission speedup at d ~10 nm, proportional to 1/d 2. Unfortunately, at dmore » < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Additionally, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.« less

Effects on RCS of a perfect electromagnetic conductor sphere in the presence of anisotropic plasma layer

NASA Astrophysics Data System (ADS)

Ghaffar, A.; Hussan, M. M.; Illahi, A.; Alkanhal, Majeed A. S.; Ur Rehman, Sajjad; Naz, M. Y.

2018-01-01

Effects on RCS of perfect electromagnetic conductor (PEMC) sphere by coating with anisotropic plasma layer are studied in this paper. The incident, scattered and transmitted electromagnetic fields are expanded in term of spherical vector wave functions using extended classical theory of scattering. Co and cross-polarized scattered field coefficients are obtained at the interface of free space-anisotropic plasma and at anisotropic plasma-PEMC sphere core by scattering matrices method. The presented analytical expressions are general for any perfect conducting sphere (PMC, PEC, or PEMC) with general anisotropic/isotropic material coatings that include plasma and metamaterials. The behavior of the forward and backscattered radar cross section of PEMC sphere with the variation of the magnetic field strength, incident frequency, plasma density, and effective collision frequency for the co-polarized and the cross polarized fields are investigated. It is also observed from the obtained results that anisotropic layer on PEMC sphere shows reciprocal behavior as compared to isotopic plasma layer on PEMC sphere. The comparisons of the numerical results of the presented analytical expressions with available results of some special cases show the correctness of the analysis.

Fish Passage though Hydropower Turbines: Simulating Blade Strike using the Discrete Element Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richmond, Marshall C.; Romero Gomez, Pedro DJ

mong the hazardous hydraulic conditions affecting anadromous and resident fish during their passage though turbine flows, two are believed to cause considerable injury and mortality: collision on moving blades and decompression. Several methods are currently available to evaluate these stressors in installed turbines, i.e. using live fish or autonomous sensor devices, and in reduced-scale physical models, i.e. registering collisions from plastic beads. However, a priori estimates with computational modeling approaches applied early in the process of turbine design can facilitate the development of fish-friendly turbines. In the present study, we evaluated the frequency of blade strike and nadir pressure environmentmore » by modeling potential fish trajectories with the Discrete Element Method (DEM) applied to fish-like composite particles. In the DEM approach, particles are subjected to realistic hydraulic conditions simulated with computational fluid dynamics (CFD), and particle-structure interactions—representing fish collisions with turbine blades—are explicitly recorded and accounted for in the calculation of particle trajectories. We conducted transient CFD simulations by setting the runner in motion and allowing for better turbulence resolution, a modeling improvement over the conventional practice of simulating the system in steady state which was also done here. While both schemes yielded comparable bulk hydraulic performance, transient conditions exhibited a visual improvement in describing flow variability. We released streamtraces (steady flow solution) and DEM particles (transient solution) at the same location from where sensor fish (SF) have been released in field studies of the modeled turbine unit. The streamtrace-based results showed a better agreement with SF data than the DEM-based nadir pressures did because the former accounted for the turbulent dispersion at the intake but the latter did not. However, the DEM-based strike frequency is more representative of blade-strike probability than the steady solution is, mainly because DEM particles accounted for the full fish length, thus resolving (instead of modeling) the collision event.« less

Collision cross section measurements for biomolecules within a high-resolution FT-ICR cell: theory.

PubMed

Guo, Dan; Xin, Yi; Li, Dayu; Xu, Wei

2015-04-14

In this study, an energetic hard-sphere ion-neutral collision model was proposed to bridge-link ion collision cross section (CCS) with the image current collected from a high-resolution Fourier transform ion cyclotron resonance (FT-ICR) cell. By investigating the nonlinear effects induced by high-order electric fields and image charge forces, the energetic hard-sphere collision model was validated through experiments. Suitable application regions for the energetic hard-sphere collision model, as well as for the conventional Langevin and hard-sphere collision models, were also discussed. The energetic hard-sphere collision model was applied in the extraction of ion CCSs from high-resolution FT-ICR mass spectra. Discussions in the present study also apply to FT-Orbitraps and FT-quadrupole ion traps.

Cold-nuclear-matter effects on heavy-quark production at forward and backward rapidity in d + Au collisions at √sNN = 200  GeV.

PubMed

Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Akimoto, R; Al-Bataineh, H; Al-Ta'ani, H; Alexander, J; Andrews, K R; Angerami, A; Aoki, K; Apadula, N; Appelt, E; Aramaki, Y; Armendariz, R; Aschenauer, E C; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Bannier, B; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Ben-Benjamin, J; Bennett, R; Bhom, J H; Blau, D S; Bok, J S; Boyle, K; Brooks, M L; Broxmeyer, D; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Caringi, A; Castera, P; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Conesa Del Valle, Z; Connors, M; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Gal, C; Garishvili, I; Glenn, A; Gong, H; Gong, X; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grim, G; Grosse Perdekamp, M; Gunji, T; Guo, L; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Harper, C; Hashimoto, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Hollis, R S; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Issah, M; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; John, D; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kamin, J; Kaneti, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D J; Kim, E-J; Kim, Y-J; Kim, Y K; Kinney, E; Kiss, A; Kistenev, E; Kleinjan, D; Kline, P; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotov, D; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, S H; Lee, S R; Leitch, M J; Leite, M A L; Li, X; Lichtenwalner, P; Liebing, P; Lim, S H; Linden Levy, L A; Liška, T; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malik, M D; Manion, A; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Means, N; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Miki, K; Milov, A; Mitchell, J T; Miyachi, Y; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, B H; Park, I H; Park, S K; Park, W J; Pate, S F; Patel, L; Pei, H; Peng, J-C; Pereira, H; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sarsour, M; Sato, T; Savastio, M; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shim, H H; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Sodre, T; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Tomášek, M; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Utsunomiya, K; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Woody, C L; Wright, R M; Wysocki, M; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; Yoo, J S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zelenski, A; Zhou, S

2014-06-27

The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1 < p(T) < 6  GeV/c at forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p + p collisions at √sNN = 200  GeV. In central d+Au collisions, relative to the yield in p + p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-p(T) broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d + Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radiom, Milad, E-mail: milad.radiom@unige.ch; Ducker, William, E-mail: wducker@vt.edu; Robbins, Brian

The hydrodynamic interaction of two closely spaced micron-scale spheres undergoing Brownian motion was measured as a function of their separation. Each sphere was attached to the distal end of a different atomic force microscopy cantilever, placing each sphere in a stiff one-dimensional potential (0.08 Nm{sup −1}) with a high frequency of thermal oscillations (resonance at 4 kHz). As a result, the sphere’s inertial and restoring forces were significant when compared to the force due to viscous drag. We explored interparticle gap regions where there was overlap between the two Stokes layers surrounding each sphere. Our experimental measurements are the firstmore » of their kind in this parameter regime. The high frequency of oscillation of the spheres means that an analysis of the fluid dynamics would include the effects of fluid inertia, as described by the unsteady Stokes equation. However, we find that, for interparticle separations less than twice the thickness of the wake of the unsteady viscous boundary layer (the Stokes layer), the hydrodynamic interaction between the Brownian particles is well-approximated by analytical expressions that neglect the inertia of the fluid. This is because elevated frictional forces at narrow gaps dominate fluid inertial effects. The significance is that interparticle collisions and concentrated suspensions at this condition can be modeled without the need to incorporate fluid inertia. We suggest a way to predict when fluid inertial effects can be ignored by including the gap-width dependence into the frequency number. We also show that low frequency number analysis can be used to determine the microrheology of mixtures at interfaces.« less

The effect of realistic heavy particle induced secondary electron emission coefficients on the electron power absorption dynamics in single- and dual-frequency capacitively coupled plasmas

NASA Astrophysics Data System (ADS)

Daksha, M.; Derzsi, A.; Wilczek, S.; Trieschmann, J.; Mussenbrock, T.; Awakowicz, P.; Donkó, Z.; Schulze, J.

2017-08-01

In particle-in-cell/Monte Carlo collisions (PIC/MCC) simulations of capacitively coupled plasmas (CCPs), the plasma-surface interaction is generally described by a simple model in which a constant secondary electron emission coefficient (SEEC) is assumed for ions bombarding the electrodes. In most PIC/MCC studies of CCPs, this coefficient is set to γ = 0.1, independent of the energy of the incident particle, the electrode material, and the surface conditions. Here, the effects of implementing energy-dependent secondary electron yields for ions, fast neutrals, and taking surface conditions into account in PIC/MCC simulations is investigated. Simulations are performed using self-consistently calculated effective SEECs, {γ }* , for ‘clean’ (e.g., heavily sputtered) and ‘dirty’ (e.g., oxidized) metal surfaces in single- and dual-frequency discharges in argon and the results are compared to those obtained by assuming a constant secondary electron yield of γ =0.1 for ions. In single-frequency (13.56 MHz) discharges operated under conditions of low heavy particle energies at the electrodes, the pressure and voltage at which the transition between the α- and γ-mode electron power absorption occurs are found to strongly depend on the surface conditions. For ‘dirty’ surfaces, the discharge operates in α-mode for all conditions investigated due to a low effective SEEC. In classical dual-frequency (1.937 MHz + 27.12 MHz) discharges {γ }* significantly increases with increasing low-frequency voltage amplitude, {V}{LF}, for dirty surfaces. This is due to the effect of {V}{LF} on the heavy particle energies at the electrodes, which negatively influences the quality of the separate control of ion properties at the electrodes. The new results on the separate control of ion properties in such discharges indicate significant differences compared to previous results obtained with different constant values of γ.

Gyrokinetic-water-bag modeling of low-frequency instabilities in a laboratory magnetized plasma column

NASA Astrophysics Data System (ADS)

Gravier, E.; Klein, R.; Morel, P.; Besse, N.; Bertrand, P.

2008-12-01

A new model is presented, named collisional-gyro-water-bag (CGWB), which describes the collisional drift waves and ion-temperature-gradient (ITG) instabilities in a plasma column. This model is based on the kinetic gyro-water-bag approach recently developed [P. Morel et al., Phys. Plasmas 14, 112109 (2007)] to investigate ion-temperature-gradient modes. In CGWB electron-neutral collisions have been introduced and are now taken into account. The model has been validated by comparing CGWB linear analysis with other models previously proposed and experimental results as well. Kinetic effects on collisional drift waves are investigated, resulting in a less effective growth rate, and the transition from collisional drift waves to ITG instability depending on the ion temperature gradient is studied.

Acoustic emission monitoring from a lab scale high shear granulator--a novel approach.

PubMed

Watson, N J; Povey, M J W; Reynolds, G K; Xu, B H; Ding, Y

2014-04-25

A new approach to the monitoring of granulation processes using passive acoustics together with precise control over the granulation process has highlighted the importance of particle-particle and particle-bowl collisions in acoustic emission. The results have shown that repeatable acoustic results could be obtained but only when a spray nozzle water addition system was used. Acoustic emissions were recorded from a transducer attached to the bowl and an airborne transducer. It was found that the airborne transducer detected very little from the granulation and only experienced small changes throughout the process. The results from the bowl transducer showed that during granulation the frequency content of the acoustic emission shifted towards the lower frequencies. Results from the discrete element model indicate that when larger particles are used the number of collisions the particles experience reduces. This is a result of the volume conservation methodology used in this study, therefore larger particles results in less particles. These simulation results coupled with previous theoretical work on the frequency content of an impacting sphere explain why the frequency content of the acoustic emissions reduces during granule growth. The acoustic system used was also clearly able to identify when large over-wetted granules were present in the system, highlighting its benefit for detecting undesirable operational conditions. High-speed photography was used to study if visual changes in the granule properties could be linked with the changing acoustic emissions. The high speed photography was only possible towards the latter stages of the granulation process and it was found that larger granules produced a higher magnitude of acoustic emission across a broader frequency range. Copyright © 2014 Elsevier B.V. All rights reserved.

Signatures of α clustering in ultrarelativistic collisions with light nuclei

NASA Astrophysics Data System (ADS)

Rybczyński, Maciej; Piotrowska, Milena; Broniowski, Wojciech

2018-03-01

We explore possible observable signatures of α clustering of light nuclei in ultrarelativistic nuclear collisions involving Be,97, 12C, and 16O. The clustering leads to specific spatial correlations of the nucleon distributions in the ground state, which are manifest in the earliest stage of the ultrahigh energy reaction. The formed initial state of the fireball is sensitive to these correlations, and the effect influences, after the collective evolution of the system, the hadron production in the final stage. Specifically, we study effects on the harmonic flow in collisions of light clustered nuclei with a heavy target (208Pb), showing that measures of the elliptic flow are sensitive to clusterization in Be,97, whereas triangular flow is sensitive to clusterization in 12C and 16O. Specific predictions are made for model collisions at energies available at the CERN Super Proton Synchrotron. In another exploratory development we also examine proton-beryllium collisions, where the 3 /2- ground state of Be,97 nuclei is polarized by an external magnetic field. Clusterization leads to multiplicity distributions of participant nucleons which depend on the orientation of the polarization with respect to the collision axis, as well as on the magnetic number of the state. The obtained effects on multiplicities reach a factor of a few for collisions with a large number of participant nucleons.

Comparing transverse momentum balance of b jet pairs in pp and PbPb collisions at $$\\sqrt{s_\\mathrm{NN}} =$$ 5.02 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, Albert M.

The transverse momentum balance of pairs of back-to-back b quark jets in PbPb and pp collisions recorded with the CMS detector at the LHC is reported. The center-of-mass energy in both collision systems is 5.02 TeV per nucleon pair. Compared to the pp collision baseline, b quark jets have a larger imbalance in the most central PbPb collisions, as expected from the jet quenching effect. The data are also compared to the corresponding measurement with inclusive dijets. In the most central collisions, the imbalance of b quark dijets is comparable to that of inclusive dijets.

Comparing transverse momentum balance of b jet pairs in pp and PbPb collisions at $$\\sqrt{s_\\mathrm{NN}} =$$ 5.02 TeV

DOE PAGES

Sirunyan, Albert M.

2018-03-29

The transverse momentum balance of pairs of back-to-back b quark jets in PbPb and pp collisions recorded with the CMS detector at the LHC is reported. The center-of-mass energy in both collision systems is 5.02 TeV per nucleon pair. Compared to the pp collision baseline, b quark jets have a larger imbalance in the most central PbPb collisions, as expected from the jet quenching effect. The data are also compared to the corresponding measurement with inclusive dijets. In the most central collisions, the imbalance of b quark dijets is comparable to that of inclusive dijets.

Evaluation of Deer Mirrors for Reducing Deer-Vehicle Collisions

DOT National Transportation Integrated Search

1982-05-01

Deer mirrors were placed in 12 random 0.5-mile test sections along 14.8 miles of I-95 between Topsham and Gardiner, Maine, to test the effectiveness of the mirrors in reducing deer-vehicle collisions. In nearly 4 years, 11 deer-vehicle collisions wer...

SPH simulations of high-speed collisions

NASA Astrophysics Data System (ADS)

Rozehnal, Jakub; Broz, Miroslav

2016-10-01

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

Parameterization of In-Cloud Aerosol Scavenging Due To Atmospheric Ionization: 2. Effects of Varying Particle Density

NASA Astrophysics Data System (ADS)

Zhang, Liang; Tinsley, Brian A.

2018-03-01

Simulations and parameterization of collision rate coefficients for aerosol particles with 3 μm radius droplets have been extended to a range of particle densities up to 2,000 kg m-3 for midtropospheric ( 5 km) conditions (540 hPa, -17°C). The increasing weight has no effect on collisions for particle radii less than 0.2 μm, but for greater radii the weight effect becomes significant and usually decreases the collision rate coefficient. When increasing size and density of particles make the fall speed of the particle relative to undisturbed air approach to that of the droplet, the effect of the particle falling away in the stagnation region ahead of the droplet becomes important, and the probability of frontside collisions can decrease to zero. Collisions on the rear side of the droplet can be enhanced as particle weight increases, and for this the weight effect tends to increase the rate coefficients. For charges on the droplet and for large particles with density ρ < 1,000 kg m-3 the predominant effect increases in rate coefficient due to the short-range attractive image electric force. With density ρ above about 1,000 kg m-3, the stagnation region prevents particles moving close to the droplet and reduces the effect of these short-range forces. Together with previous work, it is now possible to obtain collision rate coefficients for realistic combinations of droplet charge, particle charge, droplet radius, particle radius, particle density, and relative humidity in clouds. The parameterization allows rapid access to these values for use in cloud models.

Measurement of prompt D -meson production in p – Pb collisions at s N N = 5.02 TeV

DOE PAGES

Abelev, B.; Adam, J.; Adamová, D.; ...

2014-12-04

The p T-differential production cross sections of the prompt charmed mesons D 0, D +, D *+, and D + s and their charge conjugate in the rapidity interval –0.96 < y cms < 0.04 were measured in p–Pb collisions at a center-of-mass energy √s NN = 5.02 TeV with the ALICE detector at the LHC. The nuclear modification factor R pPb, quantifying the D-meson yield in p–Pb collisions relative to the yield in pp collisions scaled by the number of binary nucleon-nucleon collisions, is compatible within the 15%–20% uncertainties with unity in the transverse momentum interval 1 < pmore » T < 24 GeV/c. No significant difference among the R pPb of the four D-meson species is observed. The results are described within uncertainties by theoretical calculations that include initial-state effects. In conclusion, the measurement adds experimental evidence that the modification of the momentum spectrum of D mesons observed in Pb-Pb collisions with respect to pp collisions is due to strong final-state effects induced by hot partonic matter.« less

Measurement of prompt D-meson production in p-Pb collisions at √(s(NN))=5.02 TeV.

PubMed

Abelev, B; Adam, J; Adamová, D; Aggarwal, M M; Aglieri Rinella, G; 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; 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; 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; 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; Luzzi, C; 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; Meninno, E; 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; 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; 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; Ozdemir, M; 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; Zhou, Z; Zhu, H; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zimmermann, M B; Zinovjev, G; Zoccarato, Y; Zyzak, M

2014-12-05

The p_{T}-differential production cross sections of the prompt charmed mesons D^{0}, D^{+}, D^{*+}, and D_{s}^{+} and their charge conjugate in the rapidity interval -0.96

Omnidirectional photonic band gap enlarged by one-dimensional ternary unmagnetized plasma photonic crystals based on a new Fibonacci quasiperiodic structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Haifeng; Nanjing Artillery Academy, Nanjing 211132; Liu Shaobin

2012-11-15

In this paper, an omnidirectional photonic band gap realized by one-dimensional ternary unmagnetized plasma photonic crystals based on a new Fibonacci quasiperiodic structure, which is composed of homogeneous unmagnetized plasma and two kinds of isotropic dielectric, is theoretically studied by the transfer matrix method. It has been shown that such an omnidirectional photonic band gap originates from Bragg gap in contrast to zero-n gap or single negative (negative permittivity or negative permeability) gap, and it is insensitive to the incidence angle and the polarization of electromagnetic wave. From the numerical results, the frequency range and central frequency of omnidirectional photonicmore » band gap can be tuned by the thickness and density of the plasma but cease to change with increasing Fibonacci order. The bandwidth of omnidirectional photonic band gap can be notably enlarged. Moreover, the plasma collision frequency has no effect on the bandwidth of omnidirectional photonic band gap. It is shown that such new structure Fibonacci quasiperiodic one-dimensional ternary plasma photonic crystals have a superior feature in the enhancement of frequency range of omnidirectional photonic band gap compared with the conventional ternary and conventional Fibonacci quasiperiodic ternary plasma photonic crystals.« less

Tag-to-Tag Interference Suppression Technique Based on Time Division for RFID.

PubMed

Khadka, Grishma; Hwang, Suk-Seung

2017-01-01

Radio-frequency identification (RFID) is a tracking technology that enables immediate automatic object identification and rapid data sharing for a wide variety of modern applications using radio waves for data transmission from a tag to a reader. RFID is already well established in technical areas, and many companies have developed corresponding standards and measurement techniques. In the construction industry, effective monitoring of materials and equipment is an important task, and RFID helps to improve monitoring and controlling capabilities, in addition to enabling automation for construction projects. However, on construction sites, there are many tagged objects and multiple RFID tags that may interfere with each other's communications. This reduces the reliability and efficiency of the RFID system. In this paper, we propose an anti-collision algorithm for communication between multiple tags and a reader. In order to suppress interference signals from multiple neighboring tags, the proposed algorithm employs the time-division (TD) technique, where tags in the interrogation zone are assigned a specific time slot so that at every instance in time, a reader communicates with tags using the specific time slot. We present representative computer simulation examples to illustrate the performance of the proposed anti-collision technique for multiple RFID tags.

Chiral magnetic currents with QGP medium response in heavy-ion collisions at RHIC and LHC energies

NASA Astrophysics Data System (ADS)

She, Duan; Feng, Sheng-Qin; Zhong, Yang; Yin, Zhong-Bao

2018-03-01

We calculate the electromagnetic current with a more realistic approach in the RHIC and LHC energy regions in the article. We take the partons formation time as the initial time of the magnetic field response of QGP medium. The maximum electromagnetic current and the time-integrated current are two important characteristics of the chiral magnetic effect (CME), which can characterize the intensity and duration of fluctuations of CME. We consider the finite frequency response of CME to a time-varying magnetic field, find a significant impact from QGP medium feedback, and estimate the generated electromagnetic current as a function of time, beam energy and impact parameter.

A comparison of the temperature and density structure in high and low speed thermal proton flows

NASA Technical Reports Server (NTRS)

Raitt, W. J.; Schunk, R. W.; Banks, P. M.

1975-01-01

Steady-state altitude profiles of H(+) density, drift velocity, and temperature and O(+) density and temperature were deduced for a wide range of H(+) outflow velocities from subsonic to supersonic flow for plasma densities typical of both undisturbed and trough regions of the ionsophere. Allowance was made for the effects of inertia, parallel stress, and the velocity dependence of the H(+) collision frequencies. It was found that at supersonic outflow velocities there is a decrease in H(+) temperature with increasing outflow velocity. The H(+) temperatures are substantially increased above the O(+) temperatures when H(+) is flowing, with T(H+)/T(O+) reaching a maximum ratio of about 3:1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopeliovich, B. Z.; Institut fuer Theoretische Physik der Universitaet, Philosophenweg 19, D-69120 Heidelberg; Potashnikova, I. K.

Two novel QCD effects, double-color filtering and mutual boosting of the saturation scales in colliding nuclei, affect the transparency of the nuclei for quark dipoles in comparison with proton-nucleus collisions. The former effect increases the survival probability of the dipoles, since color filtering in one nucleus makes the other one more transparent. The second effect acts in the opposite direction and is stronger; it makes the colliding nuclei more opaque than in the case of pA collisions. As a result of parton saturation in nuclei the effective scale is shifted upward, which leads to an increase of the gluon densitymore » at small x. This in turn leads to a stronger transverse momentum broadening in AA compared with pA collisions, i.e., to an additional growth of the saturation momentum. Such a mutual boosting leads to a system of reciprocity equations, which result in a saturation scale, a few times higher in AA than in pA collisions at the energies of the large hadron collider (LHC). Since the dipole cross section is proportional to the saturation momentum squared, the nuclei become much more opaque for dipoles in AA than in pA collisions. For the same reason gluon shadowing turns out to be boosted to a larger magnitude compared with the product of the gluon shadowing factors in each of the colliding nuclei. All these effects make it more difficult to establish a baseline for anomalous J/{Psi} suppression in heavy ion collisions at high energies.« less

Damped Kadomtsev-Petviashvili Equation for Weakly Dissipative Solitons in Dense Relativistic Degenerate Plasmas

NASA Astrophysics Data System (ADS)

Ahmad, S.; Ata-ur-Rahman; Khan, S. A.; Hadi, F.

2017-12-01

We have investigated the properties of three-dimensional electrostatic ion solitary structures in highly dense collisional plasma composed of ultra-relativistically degenerate electrons and non-relativistic degenerate ions. In the limit of low ion-neutral collision rate, we have derived a damped Kadomtsev-Petviashvili (KP) equation using perturbation analysis. Supplemented by vanishing boundary conditions, the time varying solution of damped KP equation leads to a weakly dissipative compressive soliton. The real frequency behavior and linear damping of solitary pulse due to ion-neutral collisions is discussed. In the presence of weak transverse perturbations, soliton evolution with damping parameter and plasma density is delineated pointing out the extent of propagation using typical parameters of dense plasma in the interior of white dwarfs.

Gluon Shadowing Effects on J / ψ and Υ Production in p + P b Collisions at s N N = 115 GeV and P b + p Collisions at s N N = 72 GeV at AFTER@LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogt, R.

We exploremore » the effects of shadowing on inclusive J / ψ and Υ ( 1 S ) production at AFTER@LHC. We also present the rates as a function of p T and rapidity for p + Pb and Pb + p collisions in the proposed AFTER@LHC rapidity acceptance.« less

Gluon Shadowing Effects on J / ψ and Υ Production in p + P b Collisions at s N N = 115 GeV and P b + p Collisions at s N N = 72 GeV at AFTER@LHC

DOE PAGES

Vogt, R.

2015-01-01

We exploremore » the effects of shadowing on inclusive J / ψ and Υ ( 1 S ) production at AFTER@LHC. We also present the rates as a function of p T and rapidity for p + Pb and Pb + p collisions in the proposed AFTER@LHC rapidity acceptance.« less

Barrier-relevant crash modification factors and average costs of crashes on arterial roads in Indiana.

PubMed

Zou, Yaotian; Tarko, Andrew P

2018-02-01

The objective of this study was to develop crash modification factors (CMFs) and estimate the average crash costs applicable to a wide range of road-barrier scenarios that involved three types of road barriers (concrete barriers, W-beam guardrails, and high-tension cable barriers) to produce a suitable basis for comparing barrier-oriented design alternatives and road improvements. The intention was to perform the most comprehensive and in-depth analysis allowed by the cross-sectional method and the crash data available in Indiana. To accomplish this objective and to use the available data efficiently, the effects of barrier were estimated on the frequency of barrier-relevant (BR) crashes, the types of harmful events and their occurrence during a BR crash, and the severity of BR crash outcomes. The harmful events component added depth to the analysis by connecting the crash onset with its outcome. Further improvement of the analysis was accomplished by considering the crash outcome severity of all the individuals involved in a crash and not just drivers, utilizing hospital data, and pairing the observations with and without road barriers along same or similar road segments to better control the unobserved heterogeneity. This study confirmed that the total number of BR crashes tended to be higher where medians had installed barriers, mainly due to collisions with barriers and, in some cases, with other vehicles after redirecting vehicles back to traffic. These undesirable effects of barriers were surpassed by the positive results of reducing cross-median crashes, rollover events, and collisions with roadside hazards. The average cost of a crash (unit cost) was reduced by 50% with cable barriers installed in medians wider than 50ft. A similar effect was concluded for concrete barriers and guardrails installed in medians narrower than 50ft. The studied roadside guardrails also reduced the unit cost by 20%-30%. Median cable barriers were found to be the most effective among all the studied barriers due to the smaller increase in the crash frequency caused by these barriers and the less severe injury outcomes. More specifically, the occupants of vehicles colliding with near-side cable barriers tended to have less severe injuries than occupants of vehicles entering the median from median's farther side. The near-side cable barriers provided protection against rollover inside the median and against a potentially dangerous collision with or running over the median drain; therefore, the greatest safety benefit can be expected where cable barriers are installed at both edges of the median. The CMFs and unit crash costs for 48 road-barrier scenarios produced in this study are included in this paper. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chiral Magnetic Effect in Heavy Ion Collisions

DOE PAGES

Liao, Jinfeng

2016-12-01

The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. We show it is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields |Β →|~m 2 π are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. Lastly, in this contribution we give amore » brief overview on the status of such efforts.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daligault, Jérôme, E-mail: daligaul@lanl.gov

2016-03-15

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

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

NASA Astrophysics Data System (ADS)

Daligault, Jérôme

2016-03-01

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

Comparing transverse momentum balance of b jet pairs in pp and PbPb collisions at √{s_{NN}}=5.02 TeV

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Grossmann, J.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; Pree, E.; Rad, N.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Spanring, M.; Spitzbart, D.; Taurok, A.; Waltenberger, W.; Wittmann, J.; Wulz, C.-E.; Zarucki, M.; Chekhovsky, V.; Mossolov, V.; Suarez Gonzalez, J.; De Wolf, E. A.; Di Croce, D.; Janssen, X.; Lauwers, J.; Pieters, M.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; De Bruyn, I.; De Clercq, J.; Deroover, K.; Flouris, G.; Lontkovskyi, D.; Lowette, S.; Marchesini, I.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Beghin, D.; Bilin, B.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Dorney, B.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Kalsi, A. K.; Lenzi, T.; Luetic, J.; Seva, T.; Starling, E.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Roskas, C.; Trocino, D.; Tytgat, M.; Verbeke, W.; Vermassen, B.; Vit, M.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caputo, C.; Caudron, A.; David, P.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Saggio, A.; Vidal Marono, M.; Wertz, S.; Zobec, J.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correia Silva, G.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Coelho, E.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; Fonseca De Souza, S.; Malbouisson, H.; Medina Jaime, M.; Melo De Almeida, M.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Sanchez Rosas, L. 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S.; Oh, Y. D.; Sekmen, S.; Son, D. C.; Yang, Y. C.; Kim, H.; Moon, D. H.; Oh, G.; Brochero Cifuentes, J. A.; Goh, J.; Kim, T. J.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Ha, S.; Hong, B.; Jo, Y.; Kim, Y.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Almond, J.; Kim, J.; Kim, J. S.; Lee, H.; Lee, K.; Nam, K.; Oh, S. B.; Radburn-Smith, B. C.; Seo, S. h.; Yang, U. K.; Yoo, H. D.; Yu, G. B.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Choi, Y.; Hwang, C.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Reyes-Almanza, R.; Ramirez-Sanchez, G.; Duran-Osuna, M. C.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-De La Cruz, I.; Rabadan-Trejo, R. I.; Lopez-Fernandez, R.; Mejia Guisao, J.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Oropeza Barrera, C.; Vazquez Valencia, F.; Eysermans, J.; Pedraza, I.; Salazar Ibarguen, H. A.; Uribe Estrada, C.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Saddique, A.; Shah, M. A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Szleper, M.; Traczyk, P.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Pyskir, A.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Di Francesco, A.; Faccioli, P.; Galinhas, B.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. V.; Seixas, J.; Strong, G.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Afanasiev, S.; Bunin, P.; Gavrilenko, M.; Golutvin, I.; Gorbunov, I.; Kamenev, A.; Karjavin, V.; Lanev, A.; Malakhov, A.; Matveev, V.; Moisenz, P.; Palichik, V.; Perelygin, V.; Shmatov, S.; Shulha, S.; Skatchkov, N.; Smirnov, V.; Voytishin, N.; Zarubin, A.; Ivanov, Y.; Kim, V.; Kuznetsova, E.; Levchenko, P.; Murzin, V.; Oreshkin, V.; Smirnov, I.; Sosnov, D.; Sulimov, V.; Uvarov, L.; Vavilov, S.; Vorobyev, A.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Karneyeu, A.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Spiridonov, A.; Stepennov, A.; Stolin, V.; Toms, M.; Vlasov, E.; Zhokin, A.; Aushev, T.; Bylinkin, A.; Chistov, R.; Danilov, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Tarkovskii, E.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Rusakov, S. V.; Terkulov, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Demiyanov, A.; Ershov, A.; Gribushin, A.; Kodolova, O.; Korotkikh, V.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Vardanyan, I.; Blinov, V.; Shtol, D.; Skovpen, Y.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Elumakhov, D.; Godizov, A.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Mandrik, P.; Petrov, V.; Ryutin, R.; Sobol, A.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Babaev, A.; Adzic, P.; Cirkovic, P.; Devetak, D.; Dordevic, M.; Milosevic, J.; Alcaraz Maestre, J.; Bachiller, I.; Barrio Luna, M.; Cerrada, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Moran, D.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Redondo, I.; Romero, L.; Soares, M. S.; Triossi, A.; Álvarez Fernández, A.; Albajar, C.; de Trocóniz, J. F.; Cuevas, J.; Erice, C.; Fernandez Menendez, J.; Folgueras, S.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Vischia, P.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Chazin Quero, B.; Duarte Campderros, J.; Fernandez, M.; Fernández Manteca, P. J.; Garcia-Ferrero, J.; García Alonso, A.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Martinez Ruiz del Arbol, P.; Matorras, F.; Piedra Gomez, J.; Prieels, C.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Akgun, B.; Auffray, E.; Baillon, P.; Ball, A. H.; Barney, D.; Bendavid, J.; Bianco, M.; Bocci, A.; Botta, C.; Camporesi, T.; Cepeda, M.; Cerminara, G.; Chapon, E.; Chen, Y.; d'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; De Gruttola, M.; De Roeck, A.; Deelen, N.; Dobson, M.; du Pree, T.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Everaerts, P.; Fallavollita, F.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gilbert, A.; Gill, K.; Glege, F.; Gulhan, D.; Hegeman, J.; Innocente, V.; Jafari, A.; Janot, P.; Karacheban, O.; Kieseler, J.; Knünz, V.; Kornmayer, A.; Krammer, M.; Lange, C.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Malgeri, L.; Mannelli, M.; Martelli, A.; Meijers, F.; Merlin, J. A.; Mersi, S.; Meschi, E.; Milenovic, P.; Moortgat, F.; Mulders, M.; Neugebauer, H.; Ngadiuba, J.; Orfanelli, S.; Orsini, L.; Pantaleo, F.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Pitters, F. M.; Rabady, D.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Sakulin, H.; Schäfer, C.; Schwick, C.; Seidel, M.; Selvaggi, M.; Sharma, A.; Silva, P.; Sphicas, P.; Stakia, A.; Steggemann, J.; Stoye, M.; Tosi, M.; Treille, D.; Tsirou, A.; Veckalns, V.; Verweij, M.; Zeuner, W. D.; Bertl, W.; Caminada, L.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Wiederkehr, S. A.; Backhaus, M.; Bäni, L.; Berger, P.; Casal, B.; Chernyavskaya, N.; Dissertori, G.; Dittmar, M.; Donegà, M.; Dorfer, C.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Klijnsma, T.; Lustermann, W.; Marionneau, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; NessiTedaldi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Reichmann, M.; Ruini, D.; Sanz Becerra, D. A.; Schönenberger, M.; Shchutska, L.; Tavolaro, V. R.; Theofilatos, K.; Vesterbacka Olsson, M. L.; Wallny, R.; Zhu, D. H.; Aarrestad, T. K.; Amsler, C.; Brzhechko, D.; Canelli, M. F.; De Cosa, A.; Del Burgo, R.; Donato, S.; Galloni, C.; Hreus, T.; Kilminster, B.; Neutelings, I.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Schweiger, K.; Seitz, C.; Takahashi, Y.; Zucchetta, A.; Candelise, V.; Chang, Y. H.; Cheng, K. y.; Doan, T. H.; Jain, Sh.; Khurana, R.; Kuo, C. M.; Lin, W.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chao, Y.; Chen, K. F.; Chen, P. H.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Paganis, E.; Psallidas, A.; Steen, A.; Tsai, J. f.; Asavapibhop, B.; Kovitanggoon, K.; Singh, G.; Srimanobhas, N.; Bat, A.; Boran, F.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. E.; Kara, O.; Kayis Topaksu, A.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Sunar Cerci, D.; Tok, U. G.; Topakli, H.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Karapinar, G.; Ocalan, K.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Tekten, S.; Yetkin, E. A.; Agaras, M. N.; Atay, S.; Cakir, A.; Cankocak, K.; Komurcu, Y.; Grynyov, B.; Levchuk, L.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Davignon, O.; Flacher, H.; Goldstein, J.; Heath, G. P.; Heath, H. F.; Kreczko, L.; Newbold, D. M.; Paramesvaran, S.; Sakuma, T.; Seif El Nasr-storey, S.; Smith, D.; Smith, V. J.; Belyaev, A.; Brew, C.; Brown, R. M.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Linacre, J.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Womersley, W. J.; Auzinger, G.; Bainbridge, R.; Bloch, P.; Borg, J.; Breeze, S.; Buchmuller, O.; Bundock, A.; Casasso, S.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; Della Negra, M.; Di Maria, R.; Elwood, A.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Komm, M.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Matsushita, T.; Nash, J.; Nikitenko, A.; Palladino, V.; Pesaresi, M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Shtipliyski, A.; Strebler, T.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wardle, N.; Winterbottom, D.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Morton, A.; Reid, I. D.; Teodorescu, L.; Zahid, S.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Smith, C.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Hadley, M.; Hakala, J.; Heintz, U.; Hogan, J. M.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Lee, J.; Mao, Z.; Narain, M.; Pazzini, J.; Piperov, S.; Sagir, S.; Syarif, R.; Yu, D.; Band, R.; Brainerd, C.; Breedon, R.; Burns, D.; Calderon De La Barca Sanchez, M.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Stolp, D.; Taylor, D.; Tos, K.; Tripathi, M.; Wang, Z.; Zhang, F.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Regnard, S.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Karapostoli, G.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Si, W.; Wang, L.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Gilbert, D.; Hashemi, B.; Holzner, A.; Klein, D.; Kole, G.; Krutelyov, V.; Letts, J.; Masciovecchio, M.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Citron, M.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; Gouskos, L.; Heller, R.; Incandela, J.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bornheim, A.; Bunn, J.; Lawhorn, J. M.; Newman, H. B.; Nguyen, T. Q.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Wilkinson, R.; Xie, S.; Zhang, Z.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Mudholkar, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; MacDonald, E.; Mulholland, T.; Stenson, K.; Ulmer, K. A.; Wagner, S. R.; Alexander, J.; Chaves, J.; Cheng, Y.; Chu, J.; Datta, A.; Mcdermott, K.; Mirman, N.; Patterson, J. R.; Quach, D.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Abdullin, S.; Albrow, M.; Alyari, M.; Apollinari, G.; Apresyan, A.; Apyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cerati, G. B.; Cheung, H. W. K.; Chlebana, F.; Cremonesi, M.; Duarte, J.; Elvira, V. D.; Freeman, J.; Gecse, Z.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hanlon, J.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kortelainen, M. J.; Kreis, B.; Lammel, S.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Savoy-Navarro, A.; Schneider, B.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Wu, W.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Field, R. D.; Furic, I. K.; Gleyzer, S. V.; Joshi, B. M.; Konigsberg, J.; Korytov, A.; Kotov, K.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Shi, K.; Sperka, D.; Terentyev, N.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Joshi, Y. R.; Linn, S.; Markowitz, P.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Martinez, G.; Perry, T.; Prosper, H.; Saha, A.; Santra, A.; Sharma, V.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Dittmer, S.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Tonjes, M. B.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Khalil, S.; Kropivnit-skaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Rogan, C.; Royon, C.; Sanders, S.; Schmitz, E.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Modak, A.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Rebassoo, F.; Wright, D.; Baden, A.; Baron, O.; Belloni, A.; Eno, S. C.; Feng, Y.; Ferraioli, C.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Azzolini, V.; Barbieri, R.; Baty, A.; Bauer, G.; Bi, R.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Harris, P.; Hsu, D.; Hu, M.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Stephans, G. S. F.; Sumorok, K.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Zhaozhong, S.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Turkewitz, J.; Wadud, M. A.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Golf, F.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Godshalk, A.; Harrington, C.; Iashvili, I.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Freer, C.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Orimoto, T.; Teixeira De Lima, R.; Wamorkar, T.; Wang, B.; Wisecarver, A.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Bucci, R.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Li, W.; Loukas, N.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Siddireddy, P.; Smith, G.; Taroni, S.; Wayne, M.; Wightman, A.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Ling, T. Y.; Luo, W.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Higginbotham, S.; Kalogeropoulos, A.; Lange, D.; Luo, J.; Marlow, D.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Salfeld-Nebgen, J.; Stickland, D.; Tully, C.; Malik, S.; Norberg, S.; Barker, A.; Barnes, V. E.; Das, S.; Gutay, L.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Peng, C. C.; Qiu, H.; Schulte, J. F.; Sun, J.; Wang, F.; Xiao, R.; Xie, W.; Cheng, T.; Dolen, J.; Parashar, N.; Chen, Z.; Ecklund, K. M.; Freed, S.; Geurts, F. J. M.; Guilbaud, M.; Kilpatrick, M.; Li, W.; Michlin, B.; Padley, B. P.; Roberts, J.; Rorie, J.; Shi, W.; Tu, Z.; Zabel, J.; Zhang, A.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Ciesielski, R.; Goulianos, K.; Mesropian, C.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Mengke, T.; Muthumuni, S.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Padeken, K.; Ruiz Alvarez, J. D.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Joyce, M.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Wang, Y.; Wolfe, E.; Xia, F.; Harr, R.; Karchin, P. E.; Poudyal, N.; Sturdy, J.; Thapa, P.; Zaleski, S.; Brodski, M.; Buchanan, J.; Caillol, C.; Carlsmith, D.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Rekovic, V.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Woods, N.

2018-03-01

The transverse momentum balance of pairs of back-to-back b quark jets in PbPb and pp collisions recorded with the CMS detector at the LHC is reported. The center-of-mass energy in both collision systems is 5.02 TeV per nucleon pair. Compared to the pp collision baseline, b quark jets have a larger imbalance in the most central PbPb collisions, as expected from the jet quenching effect. The data are also compared to the corresponding measurement with inclusive dijets. In the most central collisions, the imbalance of b quark dijets is comparable to that of inclusive dijets. [Figure not available: see fulltext.

Motorcyclists safety system to avoid rear end collisions based on acoustic signatures

NASA Astrophysics Data System (ADS)

Muzammel, M.; Yusoff, M. Zuki; Malik, A. Saeed; Mohamad Saad, M. Naufal; Meriaudeau, F.

2017-03-01

In many Asian countries, motorcyclists have a higher fatality rate as compared to other vehicles. Among many other factors, rear end collisions are also contributing for these fatalities. Collision detection systems can be useful to minimize these accidents. However, the designing of efficient and cost effective collision detection system for motorcyclist is still a major challenge. In this paper, an acoustic information based, cost effective and efficient collision detection system is proposed for motorcycle applications. The proposed technique uses the Short time Fourier Transform (STFT) to extract the features from the audio signal and Principal component analysis (PCA) has been used to reduce the feature vector length. The reduction of feature length, further increases the performance of this technique. The proposed technique has been tested on self recorded dataset and gives accuracy of 97.87%. We believe that this method can help to reduce a significant number of motorcycle accidents.

The effect of electron collisions on rotational excitation of cometary water

NASA Technical Reports Server (NTRS)

Xie, Xingfa; Mumma, Michael J.

1991-01-01

The e-H2O collisional rate for exciting rotational transitions in cometary water is evaluated for conditions found in Comet Halley. The e-H2O collisional rate exceeds that for excitation by neutral-neutral collisions at distances exceeding 3000 km from the cometary nucleus, in the case of the O sub 00 yields 1 sub 11 transition. The estimates are based on theoretical and experimental studies of e-H2O collisions, on ion and electron parameters acquired in-situ by instruments on the Giotto and Vega spacecraft, and on results obtained from models of the cometary ionosphere. The contribution of electron collisions may explain the need for large water-water cross-sections in models which neglect the effect of electrons. The importance of electron collisions is enhanced for populations of water molecules in regions where their rotational lines are optically thick.

Importance of non-flow in mixed-harmonic multi-particle correlations in small collision systems

NASA Astrophysics Data System (ADS)

Huo, Peng; Gajdošová, Katarína; Jia, Jiangyong; Zhou, You

2018-02-01

Recently CMS Collaboration measured mixed-harmonic four-particle azimuthal correlations, known as symmetric cumulants SC (n , m), in pp and p+Pb collisions, and interpreted the non-zero SC (n , m) as evidence for long-range collectivity in these small collision systems. Using the PYTHIA and HIJING models which do not have genuine long-range collectivity, we show that the CMS results, obtained with standard cumulant method, could be dominated by non-flow effects associated with jet and dijets, especially in pp collisions. We show that the non-flow effects are largely suppressed using the recently proposed subevent cumulant methods by requiring azimuthal correlation between two or more pseudorapidity ranges. We argue that the reanalysis of SC (n , m) using the subevent method in experiments is necessary before they can used to provide further evidences for a long-range multi-particle collectivity and constraints on theoretical models in small collision systems.

Flavor-dependent eigenvolume interactions in a hadron resonance gas

NASA Astrophysics Data System (ADS)

Alba, P.; Vovchenko, V.; Gorenstein, M. I.; Stoecker, H.

2018-06-01

Eigenvolume effects in the hadron resonance gas (HRG) model are studied for experimental hadronic yields in nucleus-nucleus collisions. If particle eigenvolumes are different for different hadron species, the excluded volume HRG (EV-HRG) improves fits to multiplicity data. In particular, using different mass-volume relations for strange and non-strange hadrons we observe a remarkable improvement in the quality of the fits. This effect appears to be rather insensitive to other details in the schemes employed in the EV-HRG. We show that the parameters found from fitting the data of the ALICE Collaboration in central Pb+Pb collisions at the collision energy √{sNN } = 2.76 TeV entail the same improvement for all centralities at the same collision energy, and for the RHIC and SPS data at lower collision energies. Our findings are put in the context of recent fits of lattice QCD results.

Measurements of J/ψ Production and Polarization in p+p and p+Au Collisions at s NN = 200 GeV with the STAR Experiment

NASA Astrophysics Data System (ADS)

Liu, Zhen

We present the measurements of J/ψ production at mid-rapidity via the di-muon decay channel in p+p and p+Au collisions at s NN = 200 GeV by the STAR experiment at RHIC. In p+p collisions, the measured inclusive J/ψ cross section can be qualitatively described by model calculations. The J/ψ polarization parameters, λ𝜃, λϕ as well as the frame-invariant quantity λinv, are presented as a function of transverse momentum in both the helicity and Collins-Soper frames. No significant polarization is observed. In addition, the nuclear modification factor for inclusive J/ψ in p+Au collisions is similar to that measured in d+Au collisions and favors an additional nuclear absorption effect on top of the nuclear PDF effect.

Giant Primeval Magnetic Dipoles

NASA Astrophysics Data System (ADS)

Thompson, Christopher

2017-07-01

Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.

How Hot are Your Ions Really? A Threshold Collision-Induced Dissociation Study of Substituted Benzylpyridinium "Thermometer" Ions

NASA Astrophysics Data System (ADS)

Carpenter, John E.; McNary, Christopher P.; Furin, April; Sweeney, Andrew F.; Armentrout, P. B.

2017-09-01

The first absolute experimental bond dissociation energies (BDEs) for the main heterolytic bond cleavages of four benzylpyridinium "thermometer" ions are measured using threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. In this experiment, substituted benzylpyridinium ions are introduced into the apparatus using an electrospray ionization source, thermalized, and collided with Xe at varied kinetic energies to determine absolute cross-sections for these reactions. Various effects are accounted for, including kinetic shifts, multiple collisions, and internal and kinetic energy distributions. These experimentally measured 0 K BDEs are compared with computationally predicted values at the B3LYP-GD3BJ, M06-GD3, and MP2(full) levels of theory with a 6-311+G(2d,2p) basis set using vibrational frequencies and geometries determined at the B3LYP/6-311+G(d,p) level. Additional dissociation pathways are observed for nitrobenzylpyridinium experimentally and investigated using these same levels of theory. Experimental BDEs are also compared against values in the literature at the AM1, HF, B3LYP, B3P86, and CCSD(T) levels of theory. Of the calculated values obtained in this work, the MP2(full) level of theory with counterpoise corrections best reproduces the experimental results, as do the similar literature CCSD(T) values. Lastly, the survival yield method is used to determine the characteristic temperature (Tchar) of the electrospray source prior to the thermalization region and to confirm efficient thermalization. [Figure not available: see fulltext.

Recent Development on O(+) - O Collision Frequency and Ionosphere-Thermosphere Coupling

NASA Technical Reports Server (NTRS)

Omidvar, K.; Menard, R.

1999-01-01

The collision frequency between an oxygen atom and its singly charged ion controls the momentum transfer between the ionosphere and the thermosphere. There has been a long standing discrepancy, extending over a decade, between the theoretical and empirical determination of this frequency: the empirical value of this frequency exceeded the theoretical value by a factor of 1.7. Recent improvements in theory were obtained by using accurate oxygen ion-oxygen atom potential energy curves, and partial wave quantum mechanical calculations. We now have applied three independent statistical methods to the observational data, obtained at the MIT/Millstone Hill Observatory, consisting of two sets A and B. These methods give results consistent with each other, and together with the recent theoretical improvements, bring the ratio close to unity, as it should be. The three statistical methods lead to an average for the ratio of the empirical to the theoretical values equal to 0.98, with an uncertainty of +/-8%, resolving the old discrepancy between theory and observation. The Hines statistics, and the lognormal distribution statistics, both give lower and upper bounds for the Set A equal to 0.89 and 1.02, respectively. The related bounds for the Set B are 1.06 and 1.17. The average values of these bounds thus bracket the ideal value of the ratio which should be equal to unity. The main source of uncertainties are errors in the profile of the oxygen atom density, which is of the order of 11%. An alternative method to find the oxygen atom density is being suggested.

Target Strength of Southern Resident Killer Whales (Orcinus orca): Measurement and Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Jinshan; Deng, Zhiqun; Carlson, Thomas J.

2012-04-04

A major criterion for tidal power licensing in Washington’s Puget Sound is the management of the risk of injury to killer whales due to collision with moving turbine blades. An active monitoring system is being proposed for killer whale detection, tracking, and alerting that links to and triggers temporary turbine shutdown when there is risk of collision. Target strength (TS) modeling of the killer whale is critical to the design and application of any active monitoring system. A 1996 study performed a high-resolution measurement of acoustic reflectivity as a function of frequency of a female bottlenose dolphin (2.2 m length)more » at broadside aspect and TS as a function of incident angle at 67 kHz frequency. Assuming that killer whales share similar morphology structure with the bottlenose dolphin, we extrapolated the TS of an adult killer whale 7.5 m in length at 67 kHz frequency with -8 dB at broadside aspect and -28 dB at tail side. The backscattering data from three Southern Resident killer whales were analyzed to obtain the TS measurement. These data were collected at Lime Kiln State Park using a split-beam system deployed from a boat. The TS of the killer whale at higher frequency (200 kHz) was estimated based on a three-layer model for plane wave reflection from the lung of the whale. The TS data of killer whales were in good agreement with our model. In this paper, we also discuss and explain possible causes for measurement estimation error.« less

Equiparatition of energy for turbulent astrophysical fluids: Accounting for the unseen energy in molecular clouds

NASA Technical Reports Server (NTRS)

Zweibel, Ellen G.; Mckee, Christopher F.

1995-01-01

Molecular clouds are observed to be partially supported by turbulent pressure. The kinetic energy of the turbulence is directly measurable, but the potential energy, which consists of magnetic, thermal, and gravitational potential energy, is largly unseen. We have extended previous results on equipartition between kinetic and potential energy to show that it is likely to be a very good approximation in molecular clouds. We have used two separate approaches to demonstrate this result: For small-amplitude perturbations of a static equilibrium, we have used the energy principle analysis of Bernstein et al. (1958); this derivation applies to perturbations of arbitary wavelength. To treat perturbations of a nonstatic equilibrium, we have used the Lagrangian analysis of Dewar (1970); this analysis applies only to short-wavelength perturbations. Both analysis assume conservation of energy. Wave damping has only a small effect on equipartition if the wave frequency is small compared to the neutral-ion collision frequency; for the particular case we considered, radiative losses have no effect on equipartition. These results are then incorporated in a simple way into analyses of cloud equilibrium and global stability. We discuss the effect of Alfvenic turbulence on the Jeans mass and show that it has little effect on the magnetic critical mass.

Implications of p +Pb measurements on the chiral magnetic effect in heavy ion collisions

NASA Astrophysics Data System (ADS)

Belmont, R.; Nagle, J. L.

2017-08-01

The chiral magnetic effect (CME) is a fundamental prediction of QCD, and various observables have been proposed in heavy ion collisions to access this physics. Recently the CMS Collaboration [V. Khachatryan et al., Phys. Rev. Lett. 118, 122301 (2017), 10.1103/PhysRevLett.118.122301] has reported results from p +Pb collisions at 5.02 TeV on one such observable, the three-point correlator. The results are strikingly similar to those measured at the same particle multiplicity in Pb +Pb collisions, which have been attributed to the CME. This similarity, combined with two key assumptions about the magnetic field in p +Pb collisions, presents a major challenge to the CME picture. These two assumptions as stated in the CMS paper are (i) that the magnetic field in p +Pb collisions is smaller than that in Pb +Pb collisions and (ii) that the magnetic field direction is uncorrelated with the flow angle. We test these two postulates in the Monte Carlo-Glauber framework and find that the magnetic fields are not significantly smaller in central p +Pb collisions; however the magnetic field direction and the flow angle are indeed uncorrelated. The second finding alone gives strong evidence that the three-point correlator signal in Pb +Pb and p +Pb collisions is not an indication of the CME. Similar measurements in d +Au over a range of energies accessible at the BNL Relativistic Heavy Ion Collider would be elucidating. In the same calculational framework, we find that even in Pb +Pb collisions, where the magnetic field direction and the flow angle are correlated, there exist large inhomogeneities that are on the size scale of topological domains. These inhomogeneities need to be incorporated in any detailed CME calculation.

An Approach Toward Understanding Wildlife-Vehicle Collisions

NASA Astrophysics Data System (ADS)

Litvaitis, John A.; Tash, Jeffrey P.

2008-10-01

Among the most conspicuous environmental effects of roads are vehicle-related mortalities of wildlife. Research to understand the factors that contribute to wildlife-vehicle collisions can be partitioned into several major themes, including (i) characteristics associated with roadkill hot spots, (ii) identification of road-density thresholds that limit wildlife populations, and (iii) species-specific models of vehicle collision rates that incorporate information on roads (e.g., proximity, width, and traffic volume) and animal movements. We suggest that collision models offer substantial opportunities to understand the effects of roads on a diverse suite of species. We conducted simulations using collision models and information on Blanding’s turtles ( Emydoidea blandingii), bobcats ( Lynx rufus), and moose ( Alces alces), species endemic to the northeastern United States that are of particular concern relative to collisions with vehicles. Results revealed important species-specific differences, with traffic volume and rate of movement by candidate species having the greatest influence on collision rates. We recommend that future efforts to reduce wildlife-vehicle collisions be more proactive and suggest the following protocol. For species that pose hazards to drivers (e.g., ungulates), identify collision hot spots and implement suitable mitigation to redirect animal movements (e.g., underpasses, fencing, and habitat modification), reduce populations of problematic game species via hunting, or modify driver behavior (e.g., dynamic signage that warns drivers when animals are near roads). Next, identify those species that are likely to experience additive (as opposed to compensatory) mortality from vehicle collisions and rank them according to vulnerability to extirpation. Then combine information on the distribution of at-risk species with information on existing road networks to identify areas where immediate actions are warranted.

Rotation Studies of Jovian Trojan Asteroids

NASA Astrophysics Data System (ADS)

French, Linda M.; Stephens, Robert D.; Wasserman, Lawrence H.; Lederer, Susan M.; Rohl, Derrick A.

2011-08-01

The Jovian Trojan asteroids appear to be fundamentally different from main belt asteroids. They formed further from the sun, they are of different composition, and their collisional history is different. Lightcurve studies provide information about the distribution of rotation frequencies of a group of asteroids. For main belt asteroids larger than about 40 km in diameter, the distribution of rotation frequencies is Maxwellian (Pravec et al. 2000). This suggests that collisions determine their rotation properties. Smaller main belt asteroids, however, show a predominance of both fast and slow rotators, with the observed spin distribution apparently controlled by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect (Pravec et al. 2008). The Trojans larger than 100 km in diameter have been almost completely sampled, but lightcurves for smaller Trojans have been less well studied due to their low albedos and greater solar distances. We propose to investigate the rotation periods of 4-6 small (D < 50 km) Trojan asteroids and 6-9 Trojans in the 50-100 km size range.

Multi-fluid Approach to High-frequency Waves in Plasmas. III. Nonlinear Regime and Plasma Heating

NASA Astrophysics Data System (ADS)

Martínez-Gómez, David; Soler, Roberto; Terradas, Jaume

2018-03-01

The multi-fluid modeling of high-frequency waves in partially ionized plasmas has shown that the behavior of magnetohydrodynamic waves in the linear regime is heavily influenced by the collisional interaction between the different species that form the plasma. Here, we go beyond linear theory and study large-amplitude waves in partially ionized plasmas using a nonlinear multi-fluid code. It is known that in fully ionized plasmas, nonlinear Alfvén waves generate density and pressure perturbations. Those nonlinear effects are more pronounced for standing oscillations than for propagating waves. By means of numerical simulations and analytical approximations, we examine how the collisional interaction between ions and neutrals affects the nonlinear evolution. The friction due to collisions dissipates a fraction of the wave energy, which is transformed into heat and consequently raises the temperature of the plasma. As an application, we investigate frictional heating in a plasma with physical conditions akin to those in a quiescent solar prominence.

Evidence of final-state suppression of high-p{_ T} hadrons in Au + Au collisions using d + Au measurements at RHIC

NASA Astrophysics Data System (ADS)

Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.; Zhang, J.

Transverse momentum spectra of charged hadrons with pT < 6 GeV/c have been measured near mid-rapidity (0.2 < ɛ < 1.4) by the PHOBOS experiment at RHIC in Au + Au and d + Au collisions at {√ {s{NN}} = {200 GeV}}. The spectra for different collision centralities are compared to {p + ¯ {p}} collisions at the same energy. The resulting nuclear modification factor for central Au + Au collisions shows evidence of strong suppression of charged hadrons in the high-pT region (>2 GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-pT yields. These measurements suggest a large energy loss of the high-pT particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions. PACS: 25.75.-q

Driver responses to differing urban work zone configurations.

PubMed

Morgan, J F; Duley, A R; Hancock, P A

2010-05-01

This study reports the results of a simulator-based assessment of driver response to two different urban highway work zone configurations. One configuration represented an existing design which was contrasted with a second configuration that presented a reduced taper length prototype work zone design. Twenty-one drivers navigated the two different work zones in two different conditions, one with and one without a lead vehicle; in this case a bus. Measures of driver speed, braking, travel path, and collision frequency were recorded. Drivers navigated significantly closer to the boundary of the work area in the reduced taper length design. This proximity effect was moderated by the significant interaction between lead vehicle and taper length and such interactive effects were also observed for driver speed at the end of the work zone and the number of collisions observed within the work zone itself. These results suggest that reduced taper length poses an increase in risk to both drivers and work zone personnel, primarily when driver anticipation is reduced by foreshortened viewing distances. Increase in such risk is to a degree offset by the reduction of overall exposure to the work zone that a foreshortened taper creates. The benefits and limitations to a simulation-based approach to the assessment and prediction of driver behavior in different work zone configurations are also discussed. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Neutron lifetime measurements with a large gravitational trap for ultracold neutrons

NASA Astrophysics Data System (ADS)

Serebrov, A. P.; Kolomensky, E. A.; Fomin, A. K.; Krasnoshchekova, I. A.; Vassiljev, A. V.; Prudnikov, D. M.; Shoka, I. V.; Chechkin, A. V.; Chaikovskiy, M. E.; Varlamov, V. E.; Ivanov, S. N.; Pirozhkov, A. N.; Geltenbort, P.; Zimmer, O.; Jenke, T.; Van der Grinten, M.; Tucker, M.

2018-05-01

Neutron lifetime is one of the most important physical constants: it determines parameters of the weak interaction and predictions of primordial nucleosynthesis theory. There remains the unsolved problem of a 3.9σ discrepancy between measurements of this lifetime using neutrons in beams and those with stored ultracold neutrons (UCN). In our experiment we measure the lifetime of neutrons trapped by Earth's gravity in an open-topped vessel. Two configurations of the trap geometry are used to change the mean frequency of UCN collisions with the surfaces; this is achieved by plunging an additional surface into the trap without breaking the vacuum. The trap walls are coated with a hydrogen-less fluorine-containing polymer to reduce losses of UCN. The stability of this coating over multiple thermal cycles between 80 and 300 K was tested. At 80 K, the probability of UCN loss due to collisions with the trap walls is just 1.5% of the probability of β decay. The free neutron lifetime is determined by extrapolation to an infinitely large trap with zero collision frequency. The result of these measurements is τn=881.5 ±0 .7stat ±0 .6syst s which is consistent with the conventional value of 880.2 ± 1.0 s presented by the Particle Data Group. Future prospects for this experiment are in further cooling to 10 K, which will lead to an improved accuracy of measurement. In conclusion we present an analysis of currently available data on various measurements of the neutron lifetime.

Evaluating the impact of bike network indicators on cyclist safety using macro-level collision prediction models.

PubMed

Osama, Ahmed; Sayed, Tarek

2016-12-01

Many cities worldwide are recognizing the important role that cycling plays in creating green and livable communities. However, vulnerable road users such as cyclists are usually subjected to an elevated level of injury risk which discourages many road users to cycle. This paper studies cyclist-vehicle collisions at 134 traffic analysis zones in the city of Vancouver to assess the impact of bike network structure on cyclist safety. Several network indicators were developed using Graph theory and their effect on cyclist safety was investigated. The indicators included measures of connectivity, directness, and topography of the bike network. The study developed several macro-level (zonal) collision prediction models that explicitly incorporated bike network indicators as explanatory variables. As well, the models incorporated the actual cyclist exposure (bike kilometers travelled) as opposed to relying on proxies such as population or bike network length. The macro-level collision prediction models were developed using generalized linear regression and full Bayesian techniques, with and without spatial effects. The models showed that cyclist collisions were positively associated with bike and vehicle exposure. The exponents of the exposure variables were less than one which supports the "safety in numbers" hypothesis. Moreover, the models showed positive associations between cyclist collisions and the bike network connectivity and linearity indicators. In contrast, negative associations were found between cyclist collisions and the bike network continuity and topography indicators. The spatial effects were statistically significant in all of the developed models. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flavors in the soup: An overview of heavy-flavored jet energy loss at CMS

NASA Astrophysics Data System (ADS)

Jung, Kurt E.

The energy loss of jets in heavy-ion collisions is expected to depend on the flavor of the fragmenting parton. Thus, measurements of jet quenching as a function of flavor place powerful constraints on the thermodynamical and transport properties of the hot and dense medium. Measurements of the nuclear modification factors of the heavy flavor tagged jets from charm and bottom quarks in both PbPb and pPb collisions can quantify such energy loss effects. Specifically, pPb measurements provide crucial insights into the behavior of the cold nuclear matter effect, which is required to fully understand the hot and dense medium effects on jets in PbPb collisions. This dissertation presents the energy modification of b-jets in PbPb at √sNN = 2.76 TeV and pPb collisions at √sNN = 5.02 TeV, along with the first ever measurements of charm jets in pPb collisions at √s NN =5.02 TeV and in pp collisions at √s = 2.76 TeV. Measurements of b-jet and c-jet spectra are compared to pp data at √s = 2.76 TeV and to PYTHIA predictions at both 2.76 and 5.02 TeV. We observe a centrality-dependent suppression for b-jets in PbPb and a result that is consistent with PYTHIA for both charm and bottom jets in pPb collisions.

Numerical analysis of effects of ion-neutral collision processes on RF ICP discharge

NASA Astrophysics Data System (ADS)

Nishida, K.; Mattei, S.; Lettry, J.; Hatayama, A.

2018-01-01

The discharge process of a radiofrequency (RF) inductively coupled plasma (ICP) has been modeled by an ElectroMagnetic Particle-in-Cell Monte Carlo Collision method (EM PIC-MCC). Although the simulation had been performed by our previous model to investigate the discharge mode transition of the RF ICP from a kinetic point of view, the model neglected the collision processes of ions (H+ and H2+) with neutral particles. In this study, the RF ICP discharge process has been investigated by the latest version of the model which takes the ion-neutral collision processes into account. The basic characteristics of the discharge mode transition provided by the previous model have been verified by the comparison between the previous and present results. As for the H-mode discharge regime, on the other hand, the ion-neutral collisions play an important role in evaluating the growth of the plasma. Also, the effect of the ion-neutral collisions on the kinetic feature of the plasma has been investigated, which has highlighted the importance of kinetic perspective for modeling the RF ICP discharge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Gyeong Won; Shim, Jaewon; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr

The influence of renormalization plasma screening on the entanglement fidelity for the elastic electron-atom scattering is investigated in partially ionized dense hydrogen plasmas. The partial wave analysis and effective interaction potential are employed to obtain the scattering entanglement fidelity in dense hydrogen plasmas as functions of the collision energy, the Debye length, and the renormalization parameter. It is found that the renormalization plasma shielding enhances the scattering entanglement fidelity. Hence, we show that the transmission of the quantum information can be increased about 10% due to the renormalization shielding effect in dense hydrogen plasmas. It is also found that themore » renormalization shielding effect on the entanglement fidelity for the electron-atom collision increases with an increase of the collision energy. In addition, the renormalization shielding function increases with increasing collision energy and saturates to the unity with an increase of the Debye length.« less

Measurement of electrons from beauty-hadron decays in p-Pb collisions at √{s_{NN}}=5.02 TeV and Pb-Pb collisions at √{s_{NN}}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Albuquerque, D. S. D.; 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.; An, M.; Andrei, C.; Andrews, H. A.; Andronic, A.; Anguelov, V.; Anson, C.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; 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-Moreno, E.; Beltran, L. G. 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.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Bonora, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buhler, P.; Buitron, S. A. I.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Cabala, J.; Caffarri, D.; Cai, X.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; 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.; Crkovská, J.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; De Souza, R. D.; Deisting, A.; Deloff, A.; Deplano, C.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Di Ruzza, B.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Duggal, A. K.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eulisse, G.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; 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.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Gallio, M.; Galvan, C. D.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Garg, K.; Garg, P.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, A. S.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grosso, R.; Gruber, L.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Guzman, I. B.; Haake, R.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Hellbär, E.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Herrmann, F.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Horak, D.; Hosokawa, R.; Hristov, P.; Hughes, C.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Incani, E.; Ippolitov, M.; Irfan, M.; Isakov, V.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacak, B.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Khatun, A.; Khuntia, A.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, J.; 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.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kundu, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lapidus, K.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lazaridis, L.; Lea, R.; Leardini, L.; Lee, S.; Lehas, F.; Lehner, S.; Lehrbach, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; 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.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lupi, M.; Lutz, T. H.; 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.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzilli, M.; Mazzoni, M. A.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Mhlanga, S.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milosevic, J.; Mischke, A.; Mishra, A. N.; Mishra, T.; Miskowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montes, E.; Moreira De Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Münning, K.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Negrao De Oliveira, R. A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira Da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Oravec, M.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, D.; Pagano, P.; Paić, G.; Pal, S. K.; Palni, P.; Pan, J.; Pandey, A. K.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, J.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Peng, X.; Pereira Da Costa, H.; Peresunko, D.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Ploskon, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Poppenborg, H.; 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.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Ratza, V.; Ravasenga, I.; Read, K. F.; Redlich, K.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rodríguez Cahuantzi, M.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; 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.; Saarinen, S.; Sadhu, S.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarkar, N.; Sarma, P.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schmidt, M.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Sheikh, A. I.; Shigaki, K.; Shou, Q.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singhal, V.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stankus, P.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Sumowidagdo, S.; Suzuki, K.; Swain, S.; Szabo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thakur, D.; Thomas, D.; Tieulent, R.; Tikhonov, A.; Timmins, A. R.; Toia, A.; Tripathy, S.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vala, M.; 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.; Vauthier, A.; Vázquez Doce, O.; Vechernin, V.; Veen, A. M.; Velure, A.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Vértesi, R.; Vickovic, L.; Vigolo, S.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Virgili, T.; Vislavicius, V.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Voscek, D.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Willems, G. A.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yalcin, S.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zmeskal, J.

2017-07-01

The production of beauty hadrons was measured via semi-leptonic decays at mid-rapidity with the ALICE detector at the LHC in the transverse momentum interval 1

Centrality categorization for Rp (d)+A in high-energy collisions

NASA Astrophysics Data System (ADS)

Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Bhom, J. H.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Campbell, S.; Caringi, A.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grim, G.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Issah, M.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, A.; Kim, B. I.; Kim, D. J.; Kim, E.-J.; Kim, Y.-J.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kleinjan, D.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Li, X.; Lichtenwalner, P.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; Means, N.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miki, K.; Milov, A.; Mitchell, J. T.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nam, S.; Newby, J.; Nguyen, M.; Nihashi, M.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Orjuela Koop, J. D.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Perepelitsa, D.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Ružička, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Themann, H.; Thomas, D.; Thomas, T. L.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zhou, S.; Phenix Collaboration

2014-09-01

High-energy proton- and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and hadronization in a nuclear environment, among others. All of these effects are expected to have a significant dependence on the size of the nuclear target and the impact parameter of the collision, also known as the collision centrality. In this article, we detail a method for determining centrality classes in p (d)+A collisions via cuts on the multiplicity at backward rapidity (i.e., the nucleus-going direction) and for determining systematic uncertainties in this procedure. For d +Au collisions at √sNN =200 GeV we find that the connection to geometry is confirmed by measuring the fraction of events in which a neutron from the deuteron does not interact with the nucleus. As an application, we consider the nuclear modification factors Rp (d)+A, for which there is a bias in the measured centrality-dependent yields owing to auto correlations between the process of interest and the backward-rapidity multiplicity. We determine the bias-correction factors within this framework. This method is further tested using the hijing Monte Carlo generator. We find that for d +Au collisions at √sNN =200 GeV, these bias corrections are small and vary by less than 5% (10%) up to pT=10 (20) GeV/c. In contrast, for p +Pb collisions at √sNN =5.02 TeV we find that these bias factors are an order of magnitude larger and strongly pT dependent, likely attributable to the larger effect of multiparton interactions.

The propagation characteristics of electromagnetic waves through plasma in the near-field region of low-frequency loop antenna

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, DongLin, E-mail: donglinliu@stu.xidian.edu.cn; Li, XiaoPing; Xie, Kai

2015-10-15

A high-speed vehicle flying through the atmosphere between 100 and 20 km may suffer from a “communication blackout.” In this paper, a low frequency system with an on-board loop antenna to receive signals is presented as a potential blackout mitigation method. Because the plasma sheath is in the near-field region of the loop antenna, the traditional scattering matrix method that is developed for the far-field region may overestimate the electromagnetic (EM) wave's attenuation. To estimate the EM wave's attenuation in the near-field region, EM interference (EMI) shielding theory is introduced. Experiments are conducted, and the results verify the EMI shielding theory'smore » effectiveness. Simulations are also conducted with different plasma parameters, and the results obtained show that the EM wave's attenuation in the near-field region is far below than that in the far-field region. The EM wave's attenuation increases with the increase in electron density and decreases with the increase in collision frequency. The higher the frequency, the larger is the EM wave's attenuation. During the entire re-entry phase of a RAM-C module, the EM wave's attenuations are below 10 dB for EM waves with a frequency of 1 MHz and below 1 dB for EM waves with a frequency of 100 kHz. Therefore, the low frequency systems (e.g., Loran-C) may provide a way to transmit some key information to high-speed vehicles even during the communication “blackout” period.« less

Development of 3 DOF manipulator using ER fluid clutches for reduction of collision force

NASA Astrophysics Data System (ADS)

Boku, Kazuhiko; Nakamura, Taro

2009-02-01

.With robots and users more commonly sharing space such as in the fields of medicine and home automation, the possibility of a physical collision has increased, even though many robots use actuators with high-ratio gear trains to minimize the effects of impact. We developed a 3-DOF manipulator having a smart flexible joint using an ER fluid and a sensor-equipped pneumatic cushion. Results of position control and collision experiments using the manipulator demonstrated its effectiveness.

Initial state nuclear effects for jet production measured in s=200GeV d+Au collisions by STAR

NASA Astrophysics Data System (ADS)

STAR Collaboration; Kapitán, Jan; STAR Collaboration

2009-11-01

Full jet reconstruction in heavy-ion collisions is a promising tool for quantitative study of properties of the dense medium produced at RHIC. Measurements of d+Au collisions are important to disentangle initial state nuclear effects from medium-induced k broadening and jet quenching. We report measurements of mid-rapidity (|η|<0.4|) di-jet correlations in d+Au using high-statistics run 8 RHIC data at s=200GeV.

Identity method to study chemical fluctuations in relativistic heavy-ion collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gazdzicki, Marek; Grebieszkow, Katarzyna; Mackowiak, Maja

Event-by-event fluctuations of the chemical composition of the hadronic final state of relativistic heavy-ion collisions carry valuable information on the properties of strongly interacting matter produced in the collisions. However, in experiments incomplete particle identification distorts the observed fluctuation signals. The effect is quantitatively studied and a new technique for measuring chemical fluctuations, the identity method, is proposed. The method fully eliminates the effect of incomplete particle identification. The application of the identity method to experimental data is explained.

Energy behavior on side structure in event of ship collision subjected to external parameters.

PubMed

Prabowo, Aditya Rio; Bae, Dong Myung; Sohn, Jung Min; Cao, Bo

2016-11-01

The safety of ships in regards to collisions and groundings, as well as the navigational and structural aspects of ships, has been improved and developed up to this day by technical, administrative and nautical parties. The damage resulting from collisions could be reduced through several techniques such as designing appropriate hull structures, ensuring tightness of cargo tanks as well as observation and review on structural behaviors, whilst accounting for all involved parameters. The position during a collision can be influenced by the collisions' location and angle as these parts are included in the external dynamics of ship collisions. In this paper, the results of several collision analyses using the finite element method were used and reviewed regarding the effect of location and angle on energy characteristic. Firstly, the capabilities of the structure and its ability to resist destruction in a collision process were presented and comparisons were made to other collision cases. Three types of collisions were identified based on the relative location of contact points to each other. From the results, it was found that the estimation of internal energy by the damaged ships differed in range from 12%-24%. In the second stage, the results showed that a collision between 30 to 60 degrees produced higher level energy than a collision in the perpendicular position. Furthermore, it was concluded that striking and struck objects in collision contributed to energy and damage shape.

Effects of perturbations on space debris in supersynchronous storage orbits

NASA Astrophysics Data System (ADS)

Luu, Khanh Kim

1998-12-01

Accumulation of space debris in the geosynchronous region (GEO) has raised attention among spacefaring nations. The current mitigation measure supported is to boost satellites into supersynchronous orbits in the time before station-keeping fuel is expected to be exhausted. Because this solution does not remove mass from space, debris generation by fragmentation events remains a possibility. The collision hazard between inactive satellites in the supersynchronous region raises questions about the consequences of collisions in this regime and possible interaction with GEO. In considering the use of supersynchronous orbits for satellite disposal, the first concern is to determine the minimum safe distance above GEO such that objects in the disposal orbits will not interfere with the GEO population in the future. This involves defining the useful GEO area and studying the perturbation effects on objects in supersynchronous orbits. Thus far, research has focused on propagating the orbits of intact objects. However, in the aftermath of a collision, pieces of varying sizes and shapes can be found in orbits quite different from the parent objects' orbits. This document summarizes background information on debris in the GEO region, sources and management strategies, and then addresses the problem: Will orbits of fragments from a collision in a storage orbit occupy GEO altitudes at some time after the collision? If so, at what altitude should the storage orbit occupy such that collision fragments will not interfere with the GEO population? The methods and tools by which the effects of collisions in the supersynchronous region can be analyzed are discussed. A low-velocity collision model is employed to provide delta-velocities imparted to the fragments. An analytical study of perturbation effects, including solar and lunar third body gravitation, Earth oblateness through degree and order four, and solar radiation pressure, follows in order to evaluate the magnitude of these disturbing forces on the fragmentation debris. Validation of these results by numerical analysis using proven numerical and semianalytical orbit propagators is discussed. The results show that currently practiced reorbiting distances above GEO do not isolate debris from GEO after the occurrence of collisions in the storage orbit.

Collisions of Ir Oxide Nanoparticles with Carbon Nanopipettes: Experiments with One Nanoparticle.

PubMed

Zhou, Min; Yu, Yun; Hu, Keke; Xin, Huolin L; Mirkin, Michael V

2017-03-07

Investigating the collisions of individual metal nanoparticles (NPs) with electrodes can provide new insights into their electrocatalytic behavior, mass transport, and interactions with surfaces. Here we report a new experimental setup for studying NP collisions based on the use of carbon nanopipettes to enable monitoring multiple collision events involving the same NP captured inside the pipet cavity. A patch clamp amplifier capable of measuring pA-range currents on the microsecond time scale with a very low noise and stable background was used to record the collision transients. The analysis of current transients produced by oxidation of hydrogen peroxide at one IrO x NP provided information about the origins of deactivation of catalytic NPs and the effects of various experimental conditions on the collision dynamics. High-resolution TEM of carbon pipettes was used to attain better understanding of the NP capture and collisions.

Collisions of Ir oxide nanoparticles with carbon nanopipettes: Experiments with one nanoparticle

DOE PAGES

Zhou, Min; Yu, Yun; Hu, Keke; ...

2017-02-03

Investigating the collisions of individual metal nanoparticles (NPs) with electrodes can provide new insights into their electrocatalytic behavior, mass transport, and interactions with surfaces. Here we report a new experimental setup for studying NP collisions based on the use of carbon nanopipettes to enable monitoring multiple collision events involving the same NP captured inside the pipet cavity. A patch clamp amplifier capable of measuring pA-range currents on the microsecond time scale with a very low noise and stable background was used to record the collision transients. The analysis of current transients produced by oxidation of hydrogen peroxide at one IrOxmore » NP provided information about the origins of deactivation of catalytic NPs and the effects of various experimental conditions on the collision dynamics. Lastly, high-resolution TEM of carbon pipettes was used to attain better understanding of the NP capture and collisions.« less

Universal behavior of charged particle production in heavy ion collisions

NASA Astrophysics Data System (ADS)

Phobos Collaboration; Steinberg, Peter A.; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

2003-03-01

The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at sqrt(s_NN) = 19.6, 130 and 200 GeV. Two kinds of universal behavior are observed in charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/pbar-p and e+e- data. N_tot/(N_part/2) in nuclear collisions at high energy scales with sqrt(s) in a similar way as N_tot in e+e- collisions and has a very weak centrality dependence. This feature may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.

Universal behavior of charged particle production in heavy ion collisions at RHIC energies

NASA Astrophysics Data System (ADS)

Steinberg, Peter A.; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Phobos Collaboration

2003-04-01

The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at √ SNN = 19.6, 130 and 200 GeV. Two kinds of universal behavior are observed in charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/ overlinepp and e +e - data. < Nch>/< Npart/2> in nuclear collisions at high energy scales with √ s in a similar way as Nch in e +e - collisions and has a very weak centrality dependence. This feature may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.

Commuter motorcycle crashes in Malaysia: An understanding of contributing factors

PubMed Central

Oxley, Jennifer; Yuen, Jeremy; Ravi, Mano Deepa; Hoareau, Effie; Mohammed, Mohammed Azman Aziz; Bakar, Harun; Venkataraman, Saraswathy; Nair, Prame Kumar

2013-01-01

In Malaysia, two-thirds of reported workplace-related fatal and serious injury incidents are the result of commuting crashes (especially those involving motorcyclists), however, little is known about the contributing factors to these collisions. A telephone survey of 1,750 motorcyclists (1,004 adults who had been involved in a motorcycle commuting crash in the last 2 years and 746 adult motorcyclists who had not been involved in a motorcycle crash in the last 2 years) was undertaken. The contributions of a range of behavioural, attitudinal, employment and travel pattern factors to collision involvement were examined. The findings revealed that the majority of participants were licensed riders, rode substantial distances (most often for work purposes), and reported adopting safe riding practices (helmet wearing and buckling). However, there were some concerning findings regarding speeding behaviour, use of mobile phones while riding, and engaging in other risky behaviours. Participants who had been involved in a collision were younger (aged 25–29 years), had higher exposure (measured by distances travelled, frequency of riding, and riding on high volume and higher speed roads), reported higher rates of riding for work purposes, worked more shift hours and had a higher likelihood of riding at relatively high speeds compared with participants who had not been involved in a collision. Collisions generally occurred during morning and early evening hours, striking another vehicles, and during normal traffic flow. The implications of these findings for policy decisions and development of evidence-based behavioural/training interventions addressing key contributing factors are discussed. PMID:24406945

Holographic heavy ion collisions with baryon charge

DOE PAGES

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

2016-09-19

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

Multicharmed Baryon Production in High Energy Nuclear Collisions

NASA Astrophysics Data System (ADS)

Zhao, Jiaxing; Zhuang, Pengfei

2017-03-01

We study nuclear medium effect on multicharmed baryon production in relativistic heavy ion collisions. By solving the three-quark Schroedinger equation at finite temperature, we calculate the wave functions and Wigner functions for doubly and triply charmed baryons Ξ_{cc} and Ω_{ccc}. Their production in nuclear collisions is largely enhanced due to the combination of uncorrelated charm quarks in the quark-gluon plasma. It is most probable to discover these new particles in heavy ion collisions at the RHIC and LHC energies.

Quantum Shielding Effects on the Eikonal Collision Cross Section in Strongly Coupled Two-temperature Plasmas

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-05-01

The influence of nonisothermal and quantum shielding on the electron-ion collision process is investigated in strongly coupled two-temperature plasmas. The eikonal method is employed to obtain the eikonal scattering phase shift and eikonal cross section as functions of the impact parameter, collision energy, electron temperature, ion temperature, Debye length, and de Broglie wavelength. The results show that the quantum effect suppresses the eikonal scattering phase shift for the electron-ion collision in two-temperature dense plasmas. It is also found that the differential eikonal cross section decreases for small impact parameters. However, it increases for large impact parameters with increasing de Broglie wavelength. It is also found that the maximum position of the differential eikonal cross section is receded from the collision center with an increase in the nonisothermal character of the plasma. In addition, it is found that the total eikonal cross sections in isothermal plasmas are always greater than those in two-temperature plasmas. The variations of the eikonal cross section due to the two-temperature and quantum shielding effects are also discussed.

Large and Small Cars in Real-World Crashes -Patterns of Use, Collision Types and Injury Outcomes

PubMed Central

Thomas, Pete; Frampton, Richard

1999-01-01

Previous work examining the effect of vehicle mass has demonstrated the link with occupant injury severity. The principal factor has been related to Newtonian mechanics. This paper analyses data from the UK Co-operative Crash Injury Study and identifies other factors associated with car size. The mass of the car is found to have a predominant effect on injury outcome in frontal collisions only where the effect is seen most in injuries to the head, face and chest. Most fatal casualties in small cars die when in collision with another car in front or side collisions while the key group for large cars is frontal collisions with road-side objects. There are several characteristics of small car occupants that differ from those in large cars including gender, age and vehicle occupancy. New information in the analysis concerns the priorities in casualty reduction between small and large car occupants and the paper argues that vehicle design should take account of this variation to produce vehicles optimised for the complete range of crashes and car occupants.

ϕ Meson Production at Forward Rapidity with the PHENIX Detector at RHIC

NASA Astrophysics Data System (ADS)

Sarsour, Murad

2017-12-01

The ϕ meson production in p+p collisions is an important tool to study QCD, providing data to tune phenomenological QCD models, while in high-energy heavy-ion collisions it provides key information on the hot and dense state of the strongly interacting matter produced in such collisions. It is sensitive to the medium-induced effects such as strangeness enhancement, a phenomenon associated with soft particles in bulk matter. Measurements in the dilepton channels are especially interesting since leptons interact only electromagnetically, thus carrying the information from their production phase directly to the detector. Measurements in different nucleus-nucleus collisions allow us to perform a systematic study of the nuclear medium effects on ϕ meson production. The PHENIX detector provides the capabilities to measure the ϕ meson production in a wide range of transverse momentum and rapidity to study various cold nuclear effects such as soft multiple parton rescattering and modification of the parton distribution functions in nuclei. In this proceeding, we report the most recent PHENIX results on ϕ meson production in p+p, d+Au and Cu+Au collisions.

Methylation effects in state resolved quenching of highly vibrationally excited azabenzenes (Evib˜38 500 cm-1). I. Collisions with water

NASA Astrophysics Data System (ADS)

Elioff, Michael S.; Fang, Maosen; Mullin, Amy S.

2001-10-01

To investigate the role of molecular structure in collisions that quench highly vibrationally excited molecules, we have performed state resolved transient infrared absorption studies of energy gain in a number of rotational levels of H2O(000) resulting from collisions of water with vibrationally excited 2-methylpyridine (2-picoline) and 2,6-dimethylpyridine (2,6-lutidine) in a low-pressure gas-phase environment at 298 K. Vibrationally excited methylpyridines were prepared with ˜38 500 cm-1 of internal energy using 266 nm ultraviolet excitation to an S1 electronic state followed by rapid radiationless decay to the S0 electronic state. Collisions that populate rotationally excited states of H2O(000) were investigated with infrared absorption by monitoring the appearance of individual rotational states of H2O(000) with energies between 1000 and 2000 cm-1. Rotational state distributions for recoiling water molecules were characterized by Boltzmann temperatures of Trot=590±90 K for quenching of hot picoline and Trot=490±80 K for lutidine quenching. Doppler-broadened transient absorption line profiles show that the scattered H2O(000) molecules have laboratory-frame translational energy distributions corresponding to Ttrans≈600 K for deactivation of picoline and Ttrans≈590 K for lutidine. Energy transfer rate constant measurements indicate that rotational excitation of H2O(000) with Evib>1000 cm-1 occurs for one in 31 picoline/water collisions and one in 17 lutidine/water collisions. Comparison with earlier quenching studies on pyrazine [M. Fraelich, M. S. Elioff, and A. S. Mullin, J. Phys. Chem. 102, 9761 (1998)] and pyridine [M. S. Elioff, M. Fraelich, R. L. Sansom, and A. S. Mullin, J. Chem. Phys. 111, 3517 (1999)] indicate that, for the same initial internal energy in the hot donor, the extent of rotational excitation in water is diminished as the number of vibrational modes in the donor increases. The energy transfer probability for this pathway exhibits opposite behavior, with the larger donor molecules being more likely to excite the high energy rotations in water. These results are interpreted using a statistical description of the high energy donors and highlight the role of low frequency vibrational modes in the vibrationally hot donor molecules. A Fermi's golden rule approach is successful at explaining differences in the observed scattering dynamics for the various donor molecules.

Holography and hydrodynamics in small systems

NASA Astrophysics Data System (ADS)

Chesler, Paul M.

2016-12-01

Using holographic duality, we present results for the off-center collision of Gaussian wave packets in strongly coupled N = 4 supersymmetric Yang-Mills theory. The wave packets are thin along the collision axis and superficially at least resemble Lorentz contracted colliding protons. The collision results in the formation of a droplet of liquid of size R ∼ 1 /Teff where Teff is the effective temperature, which is the characteristic microscopic scale in strongly coupled plasma. These results demonstrate the applicability of hydrodynamics to microscopically small systems and bolster the notion that hydrodynamics can be applied to heavy-light ion collisions as well as proton-proton collisions.

Photon Shot Noise Limited Radio Frequency Electric Field Sensing Using Rydberg Atoms in Vapor Cells

NASA Astrophysics Data System (ADS)

Kumar, Santosh; Jahangiri, Akbar J.; Fan, Haoquan; Kuebler, Harald; Shaffer, James P.

2017-04-01

We report Rydberg atom-based radio frequency (RF) electrometry measurements at a sensitivity limited by probe laser photon shot noise. By utilizing the phenomena of electromagnetically induced transparency (EIT) in room temperature atomic vapor cells, Rydberg atoms can be used for absolute electric field measurements that significantly surpass conventional methods in utility, sensitivity and accuracy. We show that by using a Mach-Zehnder interferometer with homodyne detection or using frequency modulation spectroscopy with active control of residual amplitude modulation we can achieve a RF electric field detection sensitivity of 3 μVcm-1Hz/2. The sensitivity is limited by photon shot noise on the detector used to readout the probe laser of the EIT scheme. We suggest a new multi-photon scheme that can mitigate the effect of photon shot noise. The multi-photon approach allows an increase in probe laser power without decreasing atomic coherence times that result from collisions caused by an increase in Rydberg atom excitation. The multi-photon scheme also reduces Residual Doppler broadening enabling more accurate measurements to be carried out. This work is supported by DARPA, and NRO.

Interface-Resolving Simulation of Collision Efficiency of Cloud Droplets

NASA Astrophysics Data System (ADS)

Wang, Lian-Ping; Peng, Cheng; Rosa, Bodgan; Onishi, Ryo

2017-11-01

Small-scale air turbulence could enhance the geometric collision rate of cloud droplets while large-scale air turbulence could augment the diffusional growth of cloud droplets. Air turbulence could also enhance the collision efficiency of cloud droplets. Accurate simulation of collision efficiency, however, requires capture of the multi-scale droplet-turbulence and droplet-droplet interactions, which has only been partially achieved in the recent past using the hybrid direct numerical simulation (HDNS) approach. % where Stokes disturbance flow is assumed. The HDNS approach has two major drawbacks: (1) the short-range droplet-droplet interaction is not treated rigorously; (2) the finite-Reynolds number correction to the collision efficiency is not included. In this talk, using two independent numerical methods, we will develop an interface-resolved simulation approach in which the disturbance flows are directly resolved numerically, combined with a rigorous lubrication correction model for near-field droplet-droplet interaction. This multi-scale approach is first used to study the effect of finite flow Reynolds numbers on the droplet collision efficiency in still air. Our simulation results show a significant finite-Re effect on collision efficiency when the droplets are of similar sizes. Preliminary results on integrating this approach in a turbulent flow laden with droplets will also be presented. This work is partially supported by the National Science Foundation.

Heating rates in collisionally opaque alkali-metal atom traps: Role of secondary collisions

NASA Astrophysics Data System (ADS)

Beijerinck, H. C. W.

2000-12-01

Grazing collisions with background gas are the major cause of trap loss and trap heating in atom traps. To first order, these effects do not depend on the trap density. In collisionally opaque trapped atom clouds, however, scattered atoms with an energy E larger than the effective trap depth Eeff, which are destined to escape from the atom cloud, will have a finite probability for a secondary collision. This results in a contribution to the heating rate that depends on the column density of the trapped atoms, i.e., the product of density and characteristic size of the trap. For alkali-metal atom traps, secondary collisions are quite important due to the strong long-range interaction with like atoms. We derive a simple analytical expression for the secondary heating rate, showing a dependency proportional to E1/2eff. When extrapolating to a vanishing column density, only primary collisions with the background gas will contribute to the heating rate. This contribution is rather small, due to the weak long-range interaction of the usual background gas species in an ultrahigh-vacuum system-He, Ne, or Ar-with the trapped alkali-metal atoms. We conclude that the transition between trap-loss collisions and heating collisions is determined by a cutoff energy 200 μK<=Eeff<=400 μK, much smaller than the actual trap depth E in most magnetic traps. Atoms with an energy Eeff

Methods for Processing and Interpretation of AIS Signals Corrupted by Noise and Packet Collisions

NASA Astrophysics Data System (ADS)

Poļevskis, J.; Krastiņš, M.; Korāts, G.; Skorodumovs, A.; Trokšs, J.

2012-01-01

The authors deal with the operation of Automatic Identification System (AIS) used in the marine traffic monitoring to broadcast messages containing information about the vessel: id, payload, size, speed, destination etc., meant primarily for avoidance of ship collisions. To extend the radius of AIS operation, it is envisaged to dispose its receivers on satellites. However, in space, due to a large coverage area, interfering factors are especially pronounced - such as packet collision, Doppler's shift and noise impact on AIS message receiving, pre-processing and decoding. To assess the quality of an AIS receiver's operation, a test was carried out in which, varying automatically frequency, amplitude, noise, and other parameters, the data on the ability of the receiver's ability to decode AIS signals are collected. In the work, both hardware- and software-based AIS decoders were tested. As a result, quite satisfactory statistics has been gathered - both on the common and the differing features of such decoders when operating in space. To obtain reliable data on the software-defined radio AIS receivers, further research is envisaged.

Experimental study of the reactive processes in the gas phase K{sup +}+i-C{sub 3}H{sub 7}Cl collisions: A comparison with Li and Na ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguilar, J.; Lucas, J. M.; Andres, J. de

2013-05-14

Reactive collisions between alkali ions (Li{sup +}, Na{sup +}, and K{sup +}) and halogenated hydrocarbon molecules have been studied recently in our research group. In this paper, we have reported on the K{sup +}+i-C{sub 3}H{sub 7}Cl system in the 0.20-14.00 eV center-of-mass energy range using a radio frequency guided-ion beam apparatus developed in our laboratory. Aiming at increasing our knowledge about this kind of reactions, we compare our latest results for K{sup +} with those obtained previously for Li{sup +} and Na{sup +}. While the reaction channels are the same in all three cases, their energy profiles, reactivity, measured reactivemore » cross-section energy dependences, and even their reaction mechanisms, differ widely. By comparing experimentally measured reactive cross-sections as a function of the collision energy with the ab initio calculations for the different potential energy surfaces, a qualitative interpretation of the dynamics of the three reactive systems is presented in the present work.« less

Plasma non-uniformity in a symmetric radiofrequency capacitively-coupled reactor with dielectric side-wall: a two dimensional particle-in-cell/Monte Carlo collision simulation

NASA Astrophysics Data System (ADS)

Liu, Yue; Booth, Jean-Paul; Chabert, Pascal

2018-02-01

A Cartesian-coordinate two-dimensional electrostatic particle-in-cell/Monte Carlo collision (PIC/MCC) plasma simulation code is presented, including a new treatment of charge balance at dielectric boundaries. It is used to simulate an Ar plasma in a symmetric radiofrequency capacitively-coupled parallel-plate reactor with a thick (3.5 cm) dielectric side-wall. The reactor size (12 cm electrode width, 2.5 cm electrode spacing) and frequency (15 MHz) are such that electromagnetic effects can be ignored. The dielectric side-wall effectively shields the plasma from the enhanced electric field at the powered-grounded electrode junction, which has previously been shown to produce locally enhanced plasma density (Dalvie et al 1993 Appl. Phys. Lett. 62 3207-9 Overzet and Hopkins 1993 Appl. Phys. Lett. 63 2484-6 Boeuf and Pitchford 1995 Phys. Rev. E 51 1376-90). Nevertheless, enhanced electron heating is observed in a region adjacent to the dielectric boundary, leading to maxima in ionization rate, plasma density and ion flux to the electrodes in this region, and not at the reactor centre as would otherwise be expected. The axially-integrated electron power deposition peaks closer to the dielectric edge than the electron density. The electron heating components are derived from the PIC/MCC simulations and show that this enhanced electron heating results from increased Ohmic heating in the axial direction as the electron density decreases towards the side-wall. We investigated the validity of different analytical formulas to estimate the Ohmic heating by comparing them to the PIC results. The widespread assumption that a time-averaged momentum transfer frequency, v m , can be used to estimate the momentum change can cause large errors, since it neglects both phase and amplitude information. Furthermore, the classical relationship between the total electron current and the electric field must be used with caution, particularly close to the dielectric edge where the (neglected) pressure gradient term becomes significant.

Study of Z boson production in pPb collisions at √{sNN} = 5.02TeV

NASA Astrophysics Data System (ADS)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Knünz, V.; König, A.; Krammer, M.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Cornelis, T.; de Wolf, E. A.; Janssen, X.; Knutsson, A.; Lauwers, J.; Luyckx, S.; van de Klundert, M.; van Haevermaet, H.; van Mechelen, P.; van Remortel, N.; van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; de Bruyn, I.; Deroover, K.; Heracleous, N.; Keaveney, J.; Lowette, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; van Doninck, W.; van Mulders, P.; van Onsem, G. P.; van Parijs, I.; Barria, P.; Brun, H.; Caillol, C.; Clerbaux, B.; de Lentdecker, G.; Fang, W.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Maerschalk, T.; Marinov, A.; Perniè, L.; Randle-Conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Yonamine, R.; Zenoni, F.; Zhang, F.; Beernaert, K.; Benucci, L.; Cimmino, A.; Crucy, S.; Dobur, D.; Fagot, A.; Garcia, G.; Gul, M.; McCartin, J.; Ocampo Rios, A. A.; Poyraz, D.; Ryckbosch, D.; Salva, S.; Sigamani, M.; Tytgat, M.; van Driessche, W.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; Ceard, L.; Delaere, C.; Delcourt, M.; Favart, D.; Forthomme, L.; Giammanco, A.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Mertens, A.; Musich, M.; Nuttens, C.; Perrini, L.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Beliy, N.; Hammad, G. H.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Hamer, M.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; da Costa, E. M.; de Jesus Damiao, D.; de Oliveira Martins, C.; Fonseca de Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; de Souza Santos, A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Cheng, T.; Du, R.; Jiang, C. H.; Leggat, D.; Plestina, R.; Romeo, F.; Shaheen, S. 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F.; Verlage, T.; Weber, H.; Zhukov, V.; Ata, M.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Kreuzer, P.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Papacz, P.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Erdogan, Y.; Flügge, G.; Geenen, H.; Geisler, M.; Hoehle, F.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Nehrkorn, A.; Nowack, A.; Nugent, I. M.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Asin, I.; Bartosik, N.; Behnke, O.; Behrens, U.; Borras, K.; Burgmeier, A.; Campbell, A.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Gunnellini, P.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Katsas, P.; Kieseler, J.; Kleinwort, C.; Korol, I.; Lange, W.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Nayak, A.; Ntomari, E.; Perrey, H.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Seitz, C.; Spannagel, S.; Stefaniuk, N.; Trippkewitz, K. D.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Erfle, J.; Garutti, E.; Goebel, K.; Gonzalez, D.; Görner, M.; Haller, J.; Hoffmann, M.; Höing, R. S.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Lapsien, T.; Lenz, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Nowatschin, D.; Ott, J.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Pietsch, N.; Poehlsen, J.; Rathjens, D.; Sander, C.; Scharf, C.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sola, V.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Barth, C.; Baus, C.; Berger, J.; Böser, C.; Butz, E.; Chwalek, T.; Colombo, F.; de Boer, W.; Descroix, A.; Dierlamm, A.; Fink, S.; Frensch, F.; Friese, R.; Giffels, M.; Gilbert, A.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Katkov, I.; Kornmayer, A.; Lobelle Pardo, P.; Maier, B.; Mildner, H.; Mozer, M. U.; Müller, T.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Psallidas, A.; Topsis-Giotis, I.; Agapitos, A.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Strologas, J.; Bencze, G.; Hajdu, C.; Hazi, A.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Molnar, J.; Szillasi, Z.; Bartók, M.; Makovec, A.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Choudhury, S.; Mal, P.; Mandal, K.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Gupta, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Malhotra, S.; Naimuddin, M.; Nishu, N.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutta, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Banerjee, S.; Bhowmik, S.; Chatterjee, R. M.; Dewanjee, R. K.; Dugad, S.; Ganguly, S.; Ghosh, S.; Guchait, M.; Gurtu, A.; Jain, Sa.; Kole, G.; Kumar, S.; Mahakud, B.; Maity, M.; Majumder, G.; Mazumdar, K.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sarkar, T.; Sur, N.; Sutar, B.; Wickramage, N.; Chauhan, S.; Dube, S.; Kapoor, A.; Kothekar, K.; Sharma, S.; Bakhshiansohi, H.; Behnamian, H.; Etesami, S. M.; Fahim, A.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Colaleo, A.; Creanza, D.; Cristella, L.; de Filippis, N.; de Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Silvestris, L.; Venditti, R.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Cappello, G.; Chiorboli, M.; Costa, S.; di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Gori, V.; Lenzi, P.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Lo Vetere, M.; Monge, M. R.; Robutti, E.; Tosi, S.; Brianza, L.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Gerosa, R.; Ghezzi, A.; Govoni, P.; Malvezzi, S.; Manzoni, R. A.; Marzocchi, B.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Ragazzi, S.; Redaelli, N.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; di Guida, S.; Esposito, M.; Fabozzi, F.; Iorio, A. O. M.; Lanza, G.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Checchia, P.; Dall'Osso, M.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Passaseo, M.; Pazzini, J.; Pegoraro, M.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Tosi, M.; Ventura, S.; Zanetti, M.; Zotto, P.; Zucchetta, A.; Zumerle, G.; Braghieri, A.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Foà, L.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Serban, A. T.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; D'Imperio, G.; Del Re, D.; Diemoz, M.; Gelli, S.; Jorda, C.; Longo, E.; Margaroli, F.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Traczyk, P.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bellan, R.; Biino, C.; Cartiglia, N.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Finco, L.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Belforte, S.; Candelise, V.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Gobbo, B.; La Licata, C.; Marone, M.; Schizzi, A.; Zanetti, A.; Kropivnitskaya, A.; Nam, S. K.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Kong, D. J.; Lee, S.; Oh, Y. D.; Sakharov, A.; Son, D. C.; Brochero Cifuentes, J. A.; Kim, H.; Kim, T. J.; Song, S.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Hong, B.; Kim, H.; Kim, Y.; Lee, B.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Yoo, H. D.; Choi, M.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Ryu, G.; Ryu, M. S.; Choi, Y.; Goh, J.; Kim, D.; Kwon, E.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Komaragiri, J. R.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Casimiro Linares, E.; Castilla-Valdez, H.; de La Cruz-Burelo, E.; Heredia-de La Cruz, I.; Hernandez-Almada, A.; Lopez-Fernandez, R.; Mejia Guisao, J.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Vazquez Valencia, F.; Pedraza, I.; Salazar Ibarguen, H. A.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Khan, W. A.; Khurshid, T.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Romanowska-Rybinska, K.; Szleper, M.; Zalewski, P.; Brona, G.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Walczak, M.; Bargassa, P.; Beirão da Cruz E Silva, C.; di Francesco, A.; Faccioli, P.; Ferreira Parracho, P. G.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nguyen, F.; Rodrigues Antunes, J.; Seixas, J.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Vischia, P.; Afanasiev, S.; Bunin, P.; Gavrilenko, M.; Golutvin, I.; Gorbunov, I.; Kamenev, A.; Karjavin, V.; Lanev, A.; Malakhov, A.; Matveev, V.; Moisenz, P.; Palichik, V.; Perelygin, V.; Shmatov, S.; Shulha, S.; Skatchkov, N.; Smirnov, V.; Zarubin, A.; Golovtsov, V.; Ivanov, Y.; Kim, V.; Kuznetsova, E.; Levchenko, P.; Murzin, V.; Oreshkin, V.; Smirnov, I.; Sulimov, V.; Uvarov, L.; Vavilov, S.; Vorobyev, A.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Karneyeu, A.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Spiridonov, A.; Vlasov, E.; Zhokin, A.; Chadeeva, M.; Chistov, R.; Danilov, M.; Rusinov, V.; Tarkovskii, E.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Mesyats, G.; Rusakov, S. V.; Baskakov, A.; Belyaev, A.; Boos, E.; Ershov, A.; Gribushin, A.; Kaminskiy, A.; Kodolova, O.; Korotkikh, V.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Vardanyan, I.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Cirkovic, P.; Devetak, D.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; de La Cruz, B.; Delgado Peris, A.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro de Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Albajar, C.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Cuevas, J.; Fernandez Menendez, J.; Folgueras, S.; Gonzalez Caballero, I.; Palencia Cortezon, E.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Castiñeiras de Saa, J. R.; Curras, E.; de Castro Manzano, P.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Marco, R.; Martinez Rivero, C.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Rodríguez-Marrero, A. Y.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Bachtis, M.; Baillon, P.; Ball, A. H.; Barney, D.; Benaglia, A.; Bendavid, J.; Benhabib, L.; Berruti, G. M.; Bloch, P.; Bocci, A.; Bonato, A.; Botta, C.; Breuker, H.; Camporesi, T.; Castello, R.; Cepeda, M.; Cerminara, G.; D'Alfonso, M.; D'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; de Gruttola, M.; de Guio, F.; de Roeck, A.; de Visscher, S.; di Marco, E.; Dobson, M.; Dordevic, M.; Dorney, B.; Du Pree, T.; Duggan, D.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gill, K.; Giordano, D.; Girone, M.; Glege, F.; Guida, R.; Gundacker, S.; Guthoff, M.; Hammer, J.; Harris, P.; Hegeman, J.; Innocente, V.; Janot, P.; Kirschenmann, H.; Kortelainen, M. J.; Kousouris, K.; Krajczar, K.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Magini, N.; Malgeri, L.; Mannelli, M.; Martelli, A.; Masetti, L.; Meijers, F.; Mersi, S.; Meschi, E.; Moortgat, F.; Morovic, S.; Mulders, M.; Nemallapudi, M. V.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Piparo, D.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Ruan, M.; Sakulin, H.; Schäfer, C.; Schwick, C.; Seidel, M.; Sharma, A.; Silva, P.; Simon, M.; Sphicas, P.; Steggemann, J.; Stieger, B.; Stoye, M.; Takahashi, Y.; Treille, D.; Triossi, A.; Tsirou, A.; Veres, G. I.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Bachmair, F.; Bäni, L.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Eller, P.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lecomte, P.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz Del Arbol, P.; Masciovecchio, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Rossini, M.; Schönenberger, M.; Starodumov, A.; Takahashi, M.; Tavolaro, V. R.; Theofilatos, K.; Wallny, R.; Aarrestad, T. K.; Amsler, C.; Caminada, L.; Canelli, M. F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Lange, C.; Ngadiuba, J.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Yang, Y.; Chen, K. H.; Doan, T. H.; Jain, Sh.; Khurana, R.; Konyushikhin, M.; Kuo, C. M.; Lin, W.; Lu, Y. J.; Pozdnyakov, A.; Tseng, S. Y.; Yu, S. S.; Kumar, Arun; Chang, P.; Chang, Y. H.; Chang, Y. W.; Chao, Y.; Chen, K. F.; Chen, P. H.; Dietz, C.; Fiori, F.; Grundler, U.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Petrakou, E.; Tsai, J. F.; Tzeng, Y. M.; Asavapibhop, B.; Kovitanggoon, K.; Singh, G.; Srimanobhas, N.; Suwonjandee, N.; Adiguzel, A.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Gurpinar, E.; Hos, I.; Kangal, E. E.; Kayis Topaksu, A.; Onengut, G.; Ozdemir, K.; Ozturk, S.; Tali, B.; Topakli, H.; Zorbilmez, C.; Bilin, B.; Bilmis, S.; Isildak, B.; Karapinar, G.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Yetkin, E. A.; Yetkin, T.; Cakir, A.; Cankocak, K.; Sen, S.; Vardarlı, F. I.; Grynyov, B.; Levchuk, L.; Sorokin, P.; Aggleton, R.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Jacob, J.; Kreczko, L.; Lucas, C.; Meng, Z.; Newbold, D. M.; Paramesvaran, S.; Poll, A.; Sakuma, T.; Seif El Nasr-Storey, S.; Senkin, S.; Smith, D.; Smith, V. J.; Belyaev, A.; Brew, C.; Brown, R. M.; Calligaris, L.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Worm, S. D.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Bundock, A.; Burton, D.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; de Wit, A.; Della Negra, M.; Dunne, P.; Elwood, A.; Futyan, D.; Hall, G.; Iles, G.; Lane, R.; Lucas, R.; Lyons, L.; Magnan, A.-M.; Malik, S.; Nash, J.; Nikitenko, A.; Pela, J.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Seez, C.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leslie, D.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Charaf, O.; Cooper, S. I.; Henderson, C.; Rumerio, P.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Alimena, J.; Benelli, G.; Berry, E.; Cutts, D.; Ferapontov, A.; Garabedian, A.; Hakala, J.; Heintz, U.; Jesus, O.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Piperov, S.; Sagir, S.; Syarif, R.; Breedon, R.; Breto, G.; Calderon de La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; McLean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Ricci-Tam, F.; Shalhout, S.; Smith, J.; Squires, M.; Stolp, D.; Tripathi, M.; Wilbur, S.; Yohay, R.; Cousins, R.; Everaerts, P.; Florent, A.; Hauser, J.; Ignatenko, M.; Saltzberg, D.; Takasugi, E.; Valuev, V.; Weber, M.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Hanson, G.; Heilman, J.; Ivova Paneva, M.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Malberti, M.; Olmedo Negrete, M.; Shrinivas, A.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; D'Agnolo, R. T.; Derdzinski, M.; Holzner, A.; Kelley, R.; Klein, D.; Letts, J.; MacNeill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Welke, C.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Flowers, K.; Franco Sevilla, M.; Geffert, P.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Incandela, J.; McColl, N.; Mullin, S. D.; Richman, J.; Stuart, D.; Suarez, I.; West, C.; Yoo, J.; Anderson, D.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Mott, A.; Newman, H. B.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Andrews, M. B.; Azzolini, V.; Calamba, A.; Carlson, B.; Ferguson, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Ford, W. T.; Gaz, A.; Jensen, F.; Johnson, A.; Krohn, M.; Mulholland, T.; Nauenberg, U.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chatterjee, A.; Chaves, J.; Chu, J.; Dittmer, S.; Eggert, N.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Sun, W.; Tan, S. M.; Teo, W. D.; Thom, J.; Thompson, J.; Tucker, J.; Weng, Y.; Wittich, P.; Abdullin, S.; Albrow, M.; Apollinari, G.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hanlon, J.; Hare, D.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Lewis, J.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, T.; Lopes de Sá, R.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Kotov, K.; Ma, P.; Matchev, K.; Mei, H.; Milenovic, P.; Mitselmakher, G.; Rank, D.; Rossin, R.; Shchutska, L.; Snowball, M.; Sperka, D.; Terentyev, N.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Hewamanage, S.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, J. R.; Adams, T.; Askew, A.; Bein, S.; Bochenek, J.; Diamond, B.; Haas, J.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Khatiwada, A.; Prosper, H.; Weinberg, M.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Kalakhety, H.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Kurt, P.; O'Brien, C.; Sandoval Gonzalez, I. D.; Turner, P.; Varelas, N.; Wu, Z.; Zakaria, M.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Anderson, I.; Barnett, B. A.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Osherson, M.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; Xin, Y.; You, C.; Baringer, P.; Bean, A.; Bruner, C.; Kenny, R. P., III; Majumder, D.; Malek, M.; McBrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Wang, Q.; Ivanov, A.; Kaadze, K.; Khalil, S.; Makouski, M.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Lange, D.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Kellogg, R. G.; Kolberg, T.; Kunkle, J.; Lu, Y.; Mignerey, A. C.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Baty, A.; Bi, R.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; Demiragli, Z.; Di Matteo, L.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Marini, A. C.; McGinn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Sumorok, K.; Tatar, K.; Varma, M.; Velicanu, D.; Veverka, J.; Wang, J.; Wang, T. W.; Wyslouch, B.; Yang, M.; Zhukova, V.; Benvenuti, A. C.; Dahmes, B.; Evans, A.; Finkel, A.; Gude, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bartek, R.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Knowlton, D.; Kravchenko, I.; Meier, F.; Monroy, J.; Ratnikov, F.; Siado, J. E.; Snow, G. R.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira de Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Zhang, J.; Bhattacharya, S.; Hahn, K. A.; Kubik, A.; Low, J. F.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Hart, A.; Hill, C.; Hughes, R.; Ji, W.; Ling, T. Y.; Liu, B.; Luo, W.; Puigh, D.; Rodenburg, M.; Winer, B. L.; Wulsin, H. W.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Koay, S. A.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Zuranski, A.; Malik, S.; Barker, A.; Barnes, V. E.; Benedetti, D.; Bortoletto, D.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Jung, K.; Kumar, A.; Miller, D. H.; Neumeister, N.; Radburn-Smith, B. C.; Shi, X.; Shipsey, I.; Silvers, D.; Sun, J.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Chou, J. P.; Contreras-Campana, E.; Ferencek, D.; Gershtein, Y.; Halkiadakis, E.; Heindl, M.; Hidas, D.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Lath, A.; Nash, K.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Foerster, M.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; de Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Kamon, T.; Krutelyov, V.; Mueller, R.; Osipenkov, I.; Pakhotin, Y.; Patel, R.; Perloff, A.; Rose, A.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Undleeb, S.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Lin, C.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Wood, J.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Carlsmith, D.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ruggles, T.; Sarangi, T.; Savin, A.; Sharma, A.; Smith, N.; Smith, W. H.; Taylor, D.; Verwilligen, P.; Woods, N.

2016-08-01

The production of Z bosons in pPb collisions at √{sNN} = 5.02 TeV is studied by the CMS experiment via the electron and muon decay channels. The inclusive cross section is compared to pp collision predictions, and found to scale with the number of elementary nucleon-nucleon collisions. The differential cross sections as a function of the Z boson rapidity and transverse momentum are measured. Though they are found to be consistent within uncertainty with theoretical predictions both with and without nuclear effects, the forward-backward asymmetry suggests the presence of nuclear effects at large rapidities. These results provide new data for constraining nuclear parton distribution functions.

Tunable angle absorption of hyperbolic metamaterials based on plasma photonic crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Zheng; Ning, Renxia, E-mail: nrxxiner@hsu.edu.cn; Xu, Yuan

2016-06-15

We present the design of a multilayer structure of hyperbolic metamaterials based on plasma photonic crystals which composed of two kinds of traditional dielectric and plasma. The relative permittivity of hyperbolic metamaterials has been studied at certain frequency range. The absorption and reflection of the multilayer period structure at normal and oblique incident have been investigated by the transfer matrix method. We discussed that the absorption is affected by the thickness of material and the electron collision frequency γ of the plasma. The results show that an absorption band at the low frequency can be obtained at normal incident anglemore » and another absorption band at the high frequency can be found at a large incident angle. The results may be applied by logical gate, stealth, tunable angle absorber, and large angle filter.« less

Cooperation of sperm in two dimensions: synchronization, attraction, and aggregation through hydrodynamic interactions.

PubMed

Yang, Yingzi; Elgeti, Jens; Gompper, Gerhard

2008-12-01

Sperm swimming at low Reynolds number have strong hydrodynamic interactions when their concentration is high in vivo or near substrates in vitro. The beating tails not only propel the sperm through a fluid, but also create flow fields through which sperm interact with each other. We study the hydrodynamic interaction and cooperation of sperm embedded in a two-dimensional fluid by using a particle-based mesoscopic simulation method, multiparticle collision dynamics. We analyze the sperm behavior by investigating the relationship between the beating-phase difference and the relative sperm position, as well as the energy consumption. Two effects of hydrodynamic interaction are found, synchronization and attraction. With these hydrodynamic effects, a multisperm system shows swarm behavior with a power-law dependence of the average cluster size on the width of the distribution of beating frequencies.

Pinning in the flux-line-cutting regime of Bi 2Sr 2Ca 1Cu 2O 8 single crystals at high field

NASA Astrophysics Data System (ADS)

D'Anna, G.; André, M.-O.; Indenbom, M. V.; Benoit, W.

1994-09-01

Using a low-frequency torsion pendulum we show that in a Bi 2Sr 2Ca 1Cu 2O 8 single crystal the irreversibility line Birr( T) is frequency dependent down to 10 -5 Hz in the high-field regime. The activation energy has a logarithmic field dependence, U0( B)= U∗ 1n( B∗/ B). A microscopic model for flux-line-cutting and pancake collision yields quantitative expressions for U0 and for Birr( T)= B∗ exp(- T/T∗), which reproduce the experimental data very well.

Ion Cyclotron Resonant Heating (ICRH) system used on the Tandem Mirror Experiment-Upgrade (TMX-U)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferguson, S.W.; Maxwell, T.M.; Antelman, D.R.

1985-11-11

Ion Cyclotron Resonant Heating (ICRH) is part of the plasma heating system used on the TMX-U experiment. Radio frequency (RF) energy is injected into the TMX-U plasma at a frequency near the fundamental ion resonance (2 to 5 MHz). The RF fields impart high velocities to the ions in a direction perpendicular to the TMX-U magnetic field. Particle collision then converts this perpendicular heating to uniform plasma heating. This paper describes the various aspects of the ICRH system: antennas, power supplies, computer control, and data acquisition. 4 refs., 10 figs.

Evidence for transverse momentum and pseudorapidity dependent event plane fluctuations in PbPb and pPb collisions

DOE PAGES

Khachatryan, Vardan

2015-09-22

A systematic study of the factorization of long-range azimuthal two-particle correlations into a product of single-particle anisotropies is presented as a function of p T and η of both particles and as a function of the particle multiplicity in PbPb and pPb collisions. The data were taken with the CMS detector for PbPb collisions at √s NN=2.76 TeV and pPb collisions at √s NN=5.02 TeV, covering a very wide range of multiplicity. Factorization is observed to be broken as a function of both particle p T and η. When measured with particles of different p T, the magnitude of themore » factorization breakdown for the second Fourier harmonic reaches 20% for very central PbPb collisions but decreases rapidly as the multiplicity decreases. The data are consistent with viscous hydrodynamic predictions, which suggest that the effect of factorization breaking is mainly sensitive to the initial-state conditions rather than to the transport properties (e.g., shear viscosity) of the medium. The factorization breakdown is also computed with particles of different η. The effect is found to be weakest for mid-central PbPb events but becomes larger for more central or peripheral PbPb collisions, and also for very-high-multiplicity pPb collisions. The η-dependent factorization data provide new insights to the longitudinal evolution of the medium formed in heavy ion collisions.« less

Light flash observations during Apollo-Soyuz

NASA Technical Reports Server (NTRS)

Budinger, T. F.; Tobias, C. A.; Huesman, R. H.; Upham, F. T.; Wieskamp, T. F.; Schott, J. U.; Schopper, E.

1976-01-01

A total of 82 visual events was reported by two dark-adapted astronauts during a 90-minute orbit at 225 km altitude. Silver chloride crystal events for that orbit totaled 69 stopping protons and alphas per sq cm and 304 heavy ions with stopping power of 150 MeV sq cm/g or greater. The frequency of visual observations near the geomagnetic poles corresponds to calculated abundances of ions with LET greater than 5 keV per micrometer in tissue. Nuclear collisions of fast protons on C, N, and O in the retina or the abundance of stopping protons can explain the low frequency of events in the SAA for this mission in comparison with the high frequency during Skylab IV at 443 km altitude.

Effectiveness and driver acceptance of a semi-autonomous forward obstacle collision avoidance system.

PubMed

Itoh, Makoto; Horikome, Tatsuya; Inagaki, Toshiyuki

2013-09-01

This paper proposes a semi-autonomous collision avoidance system for the prevention of collisions between vehicles and pedestrians and objects on a road. The system is designed to be compatible with the human-centered automation principle, i.e., the decision to perform a maneuver to avoid a collision is made by the driver. However, the system is partly autonomous in that it turns the steering wheel independently when the driver only applies the brake, indicating his or her intent to avoid the obstacle. With a medium-fidelity driving simulator, we conducted an experiment to investigate the effectiveness of this system for improving safety in emergency situations, as well as its acceptance by drivers. The results indicate that the system effectively improves safety in emergency situations, and the semi-autonomous characteristic of the system was found to be acceptable to drivers. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

DOE PAGES

Cirigliano, Vincenzo; Paris, Mark W.; Shalgar, Shashank

2017-09-25

We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we also observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. Furthermore, we consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavormore » instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength.« less

Effects of the inner droplet of double emulsions on the film drainage during a head-on collision

NASA Astrophysics Data System (ADS)

Wang, Jingtao; Jing, Hefeng; Xu, Genmiao; Wang, Xiaoyong; Duan, Zhenya

2015-07-01

As a critical stage which severely affects the final coalescence of droplets, film drainage in the collision process of two simple droplets has been deeply studied for many years. However, the collision of multiple emulsions which contain other phases (like daughter droplets or particles) has never been studied although multiple emulsions are very important in emulsion industries nowadays. In this paper, the head-on collision of two core-shell double emulsions with equal sizes is investigated through a boundary integral method to disclose the effects of the inner droplet on the film drainage. When capillary number Ca is relatively high, due to the effect of the inner droplet on the inner circulation of mother droplets, the film drainage of double emulsions includes three stages: drainage, drainage halt, and second drainage, instead of two stages for that of simple droplets: drainage and drainage halt.

Evaluation of a Portable Collision Warning Device for Patients With Peripheral Vision Loss in an Obstacle Course.

PubMed

Pundlik, Shrinivas; Tomasi, Matteo; Luo, Gang

2015-04-01

A pocket-sized collision warning device equipped with a video camera was developed to predict impending collisions based on time to collision rather than proximity. A study was conducted in a high-density obstacle course to evaluate the effect of the device on collision avoidance in people with peripheral field loss (PFL). The 41-meter-long loop-shaped obstacle course consisted of 46 stationary obstacles from floor to head level and oncoming pedestrians. Twenty-five patients with tunnel vision (n = 13) or hemianopia (n = 12) completed four consecutive loops with and without the device, while not using any other habitual mobility aid. Walking direction and device usage order were counterbalanced. Number of collisions and preferred percentage of walking speed (PPWS) were compared within subjects. Collisions were reduced significantly by approximately 37% (P < 0.001) with the device (floor-level obstacles were excluded because the device was not designed for them). No patient had more collisions when using the device. Although the PPWS were also reduced with the device from 52% to 49% (P = 0.053), this did not account for the lower number of collisions, as the changes in collisions and PPWS were not correlated (P = 0.516). The device may help patients with a wide range of PFL avoid collisions with high-level obstacles while barely affecting their walking speed.

A novel method to study contact inhibition of locomotion using micropatterned substrates

PubMed Central

Scarpa, Elena; Roycroft, Alice; Theveneau, Eric; Terriac, Emmanuel; Piel, Matthieu; Mayor, Roberto

2013-01-01

Summary The concept of contact inhibition of locomotion (CIL) describes the ability of a cell to change the direction of its movement after contact with another cell. It has been shown to be responsible for physiological and developmental processes such as wound healing, macrophage dispersion and neural crest cell migration; whereas its loss facilitates cancer cell invasion and metastatic dissemination. Different assays have been developed to analyze CIL in tissue culture models. However, these methods have several caveats. Collisions happen at low frequency between freely migrating cells and the orientation of the cells at the time of contact is not predictable. Moreover, the computational analysis required by these assays is often complicated and it retains a certain degree of discretion. Here, we show that confinement of neural crest cell migration on a single dimension by using a micropatterned substrate allows standardized and predictable cell–cell collision. CIL can thus easily be quantified by direct measurement of simple cellular parameters such as the distance between nuclei after collision. We tested some of the signaling pathways previously identified as involved in CIL, such as small GTPases and non-canonical Wnt signaling, using this new method for CIL analysis. The restricted directionality of migration of cells in lines is a powerful strategy to obtain higher predictability and higher efficiency of the CIL response upon cell–cell collisions. PMID:24143276

The effects of in-vehicle and infrastructure-based collision warnings at signalized intersections

DOT National Transportation Integrated Search

2009-12-01

The potential effectiveness of warnings to drivers of the imminent threat of a collision with a red light violator was evaluated in an experiment that used a driving simulator. Three warnings were tested: (1) an infrastructure-based warning that imme...

Collision-induced absorption with exchange effects and anisotropic interactions: theory and application to H2 - H2.

PubMed

Karman, Tijs; van der Avoird, Ad; Groenenboom, Gerrit C

2015-02-28

We discuss three quantum mechanical formalisms for calculating collision-induced absorption spectra. First, we revisit the established theory of collision-induced absorption, assuming distinguishable molecules which interact isotropically. Then, the theory is rederived incorporating exchange effects between indistinguishable molecules. It is shown that the spectrum can no longer be written as an incoherent sum of the contributions of the different spherical components of the dipole moment. Finally, we derive an efficient method to include the effects of anisotropic interactions in the computation of the absorption spectrum. This method calculates the dipole coupling on-the-fly, which allows for the uncoupled treatment of the initial and final states without the explicit reconstruction of the many-component wave functions. The three formalisms are applied to the collision-induced rotation-translation spectra of hydrogen molecules in the far-infrared. Good agreement with experimental data is obtained. Significant effects of anisotropic interactions are observed in the far wing.

A collision model for safety evaluation of autonomous intelligent cruise control.

PubMed

Touran, A; Brackstone, M A; McDonald, M

1999-09-01

This paper describes a general framework for safety evaluation of autonomous intelligent cruise control in rear-end collisions. Using data and specifications from prototype devices, two collision models are developed. One model considers a train of four cars, one of which is equipped with autonomous intelligent cruise control. This model considers the car in front and two cars following the equipped car. In the second model, none of the cars is equipped with the device. Each model can predict the possibility of rear-end collision between cars under various conditions by calculating the remaining distance between cars after the front car brakes. Comparing the two collision models allows one to evaluate the effectiveness of autonomous intelligent cruise control in preventing collisions. The models are then subjected to Monte Carlo simulation to calculate the probability of collision. Based on crash probabilities, an expected value is calculated for the number of cars involved in any collision. It is found that given the model assumptions, while equipping a car with autonomous intelligent cruise control can significantly reduce the probability of the collision with the car ahead, it may adversely affect the situation for the following cars.

Statistics on the parameters of nonisothermal ionospheric plasma in large mesospheric electric fields

NASA Astrophysics Data System (ADS)

Martynenko, S.; Rozumenko, V.; Tyrnov, O.; Manson, A.; Meek, C.

The large V/m electric fields inherent in the mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency at D region altitudes, and consequently the ionospheric plasma in the lower part of the D region undergoes a transition into a nonisothermal state. This study is based on the databases on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude) and with the 2.3-MHz radar of the Kharkiv V. Karazin National University (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented in Meek, C. E., A. H. Manson, S. I. Martynenko, V. T. Rozumenko, O. F. Tyrnov, Remote sensing of mesospheric electric fields using MF radars, Journal of Atmospheric and Solar-Terrestrial Physics, in press. The large mesospheric electric fields is experimentally established to follow a Rayleigh distribution in the interval 0

Statistical parameters of nonisothermal lower ionospheric plasma in the electrically active mesosphere

NASA Astrophysics Data System (ADS)

Martynenko, S. I.; Rozumenko, V. T.; Tyrnov, O. F.; Manson, A. H.; Meek, C. E.

The large V/m electric fields inherent in the lower mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency and consequently of the transition of the ionospheric plasma in the lower part of the D region into a nonisothermal state. This study is based on the datasets on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude), and with the 2.3-MHz radar of the Kharkiv V. Karazin National University, Ukraine (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented by [Meek, C.E., Manson, A.H., Martynenko, S.I., Rozumenko, V.T., Tyrnov, O.F. Remote sensing of mesospheric electric fields using MF radars. J. Atmos. Solar-Terr. Phys. 66, 881-890, 2004. 10.1016/j.jastp.2004.02.002]. The large mesospheric electric fields in the 60-67-km altitude range are experimentally established to follow a Rayleigh distribution in the 0 < E < 2.5 V/m interval. These data have permitted the resulting differential distributions of relative disturbances in the electron temperature, θ, and the effective electron collision frequency, η, to be determined. The most probable θ and η values are found to be in the 1.4-2.2 interval, and hence the nonstationary state of the lower part of the D region needs to be accounted for in studying processes coupling the electrically active mesosphere and the lower ionospheric plasma.

Bird-Window Collisions at a West-Coast Urban Park Museum: Analyses of Bird Biology and Window Attributes from Golden Gate Park, San Francisco.

PubMed

Kahle, Logan Q; Flannery, Maureen E; Dumbacher, John P

2016-01-01

Bird-window collisions are a major and poorly-understood generator of bird mortality. In North America, studies of this topic tend to be focused east of the Mississippi River, resulting in a paucity of data from the Western flyways. Additionally, few available data can critically evaluate factors such as time of day, sex and age bias, and effect of window pane size on collisions. We collected and analyzed 5 years of window strike data from a 3-story building in a large urban park in San Francisco, California. To evaluate our window collision data in context, we collected weekly data on local bird abundance in the adjacent parkland. Our study asks two overarching questions: first-what aspects of a bird's biology might make them more likely to fatally strike windows; and second, what characteristics of a building's design contribute to bird-window collisions. We used a dataset of 308 fatal bird strikes to examine the relationships of strikes relative to age, sex, time of day, time of year, and a variety of other factors, including mitigation efforts. We found that actively migrating birds may not be major contributors to collisions as has been found elsewhere. We found that males and young birds were both significantly overrepresented relative to their abundance in the habitat surrounding the building. We also analyzed the effect of external window shades as mitigation, finding that an overall reduction in large panes, whether covered or in some way broken up with mullions, effectively reduced window collisions. We conclude that effective mitigation or design will be required in all seasons, but that breeding seasons and migratory seasons are most critical, especially for low-rise buildings and other sites away from urban migrant traps. Finally, strikes occur throughout the day, but mitigation may be most effective in the morning and midday.

Bird-Window Collisions at a West-Coast Urban Park Museum: Analyses of Bird Biology and Window Attributes from Golden Gate Park, San Francisco

PubMed Central

Kahle, Logan Q.; Flannery, Maureen E.; Dumbacher, John P.

2016-01-01

Bird-window collisions are a major and poorly-understood generator of bird mortality. In North America, studies of this topic tend to be focused east of the Mississippi River, resulting in a paucity of data from the Western flyways. Additionally, few available data can critically evaluate factors such as time of day, sex and age bias, and effect of window pane size on collisions. We collected and analyzed 5 years of window strike data from a 3-story building in a large urban park in San Francisco, California. To evaluate our window collision data in context, we collected weekly data on local bird abundance in the adjacent parkland. Our study asks two overarching questions: first–what aspects of a bird’s biology might make them more likely to fatally strike windows; and second, what characteristics of a building’s design contribute to bird-window collisions. We used a dataset of 308 fatal bird strikes to examine the relationships of strikes relative to age, sex, time of day, time of year, and a variety of other factors, including mitigation efforts. We found that actively migrating birds may not be major contributors to collisions as has been found elsewhere. We found that males and young birds were both significantly overrepresented relative to their abundance in the habitat surrounding the building. We also analyzed the effect of external window shades as mitigation, finding that an overall reduction in large panes, whether covered or in some way broken up with mullions, effectively reduced window collisions. We conclude that effective mitigation or design will be required in all seasons, but that breeding seasons and migratory seasons are most critical, especially for low-rise buildings and other sites away from urban migrant traps. Finally, strikes occur throughout the day, but mitigation may be most effective in the morning and midday. PMID:26731417

The Importance of the Cathode Plume and Its Interactions with the Ion Beam in Numerical Simulations of Hall Thrusters

NASA Technical Reports Server (NTRS)

Lopez Ortega, Alejandro; Mikellides, Ioannis G.

2015-01-01

Hall2De is a first-principles, 2-D axisymmetric code that solves the equations of motion for ions, electrons, and neutrals on a magnetic-field-aligned grid. The computational domain downstream of the acceleration channel exit plane is large enough to include self-consistently the cathode boundary. In this paper, we present results from numerical simulations of the H6 laboratory thruster with an internally mounted cathode, with the aim of highlighting the importance of properly accounting for the interactions between the ion beam and cathode plume. The anomalous transport of electrons across magnetic field lines in Hall2De is modelled using an anomalous collision frequency, ?anom, yielding ?anom approximately equal to omega ce (i.e., the electron cyclotron frequency) in the plume. We first show that restricting the anomalous collision frequency to only regions where the current density of ions is large does not alter the plasma discharge in the Hall thruster as long as the interaction between the ion beam and the cathode plume is captured properly in the computational domain. This implies that the boundary conditions must be placed sufficiently far as to not interfere with the electron transport in this region. These simulation results suggest that electron transport across magnetic field lines occurs largely inside the beam and may be driven by the interactions between beam ions and electrons. A second finding that puts in relevance the importance of including the cathode plume in numerical simulations is on the significance of accounting for the ion acoustic turbulence (IAT), now known to occur in the vicinity of the cathode exit. We have included in the Hall2De simulations a model of the IAT-driven anomalous collision frequency based on Sagdeev's model for saturation of the ion-acoustic instability. This implementation has allowed us to achieve excellent agreement with experimental measurements in the near plume obtained during the operation of the H6 thruster at nominal conditions (300V, 20A) and chamber background pressure of approximately 1.5 x 10(exp -5) Torr. In addition, the numerical results obtained with the latter approach exhibit less sensitivity to background pressure than previous attempts at explaining the features of the plasma properties in the near plume.

Survey of Collision Avoidance and Ranging Sensors for Mobile Robots. Revision 1

DTIC Science & Technology

1992-12-01

diagram of the Hamamatsu’s Range-Finder Chip Set, which applies the principle of triangulation (Hamamatsu Corporation, 1990) ....................... 37...platform (Courtesy Transitions Research Company ) . ............................................ 68 37. The Sensus 300 configured for 360-degree coverage... applied to the detection of metal objects located at short-range. Typical inductive sensors generate an oscillatory radio-frequency (RF) field around a

Dynamic Spectrum Management for Military Wireless Networks

DTIC Science & Technology

2010-09-01

auctions, and protocols and etiquettes . Command and control assignments are provided by the regulatory agency by reviewing specific licensing...devices and amateur licensees do not have specific frequency assignments. The Protocols and Etiquettes methods allow these devices to operate within a...with Collision Avoidance (CSMA/CA) a protocol . Etiquettes are rules that are followed without explicit interaction between devices. Simple etiquettes

Analysis of energy relaxation kinetics for control of the electron energy distributions in capacitively coupled RF discharges

NASA Astrophysics Data System (ADS)

Lee, Jung Yeol; Verboncoeur, John P.; Lee, Hae June

2018-04-01

The transition of electron energy probability functions (EEPFs) through the change of heating mode is an important issue in plasma science. A well-known example is that the increase of gas pressure, which was analyzed in terms of the ratio of the energy relaxation mean free path to the electrode gap distance, changes the EEPF from bi-Maxwellian to Maxwellian or Druyvesteyn. In this study, a new aspect of the temporal decay of kinetic energy during the energy relaxation time is theoretically analyzed and compared with a particle-in-cell Monte Carlo collision simulation of capacitively coupled plasmas. A fully kinetic description of electron transport and collisions shows drastic changes of EEPFs with the variation of the driving frequency due to the heating mode transition.

35-GHz radar sensor for automotive collision avoidance

NASA Astrophysics Data System (ADS)

Zhang, Jun

1999-07-01

This paper describes the development of a radar sensor system used for automotive collision avoidance. Because the heavy truck may have great larger radar cross section than a motorcyclist has, the radar receiver may have a large dynamic range. And multi-targets at different speed may confuse the echo spectrum causing the ambiguity between range and speed of target. To get more information about target and background and to adapt to the large dynamic range and multi-targets, a frequency modulated and pseudo- random binary sequences phase modulated continuous wave radar system is described. The analysis of this double- modulation system is given. A high-speed signal processing and data processing component are used to process and combine the data and information from echo at different direction and at every moment.

A thermal oscillating two-stream instability

NASA Technical Reports Server (NTRS)

Dysthe, K. B.; Mjolhus, E.; Rypdal, K.; Pecseli, H. L.

1983-01-01

A theory for the oscillating two-stream instability, in which the Ohmic heating of the electrons constitutes the nonlinearity, is developed for an inhomogeneous and magnetized plasma. Its possible role in explaining short-scale, field-aligned irregularities observed in ionospheric heating experiments is emphasized. The theory predicts that the initial growth of such irregularities is centered around the level of upper hybrid resonance. Furthermore, plane disturbances nearly parallel to the magnetic meridian plane have the largest growth rates. Expressions for threshold, growth rate, and transverse scale of maximum growth are obtained. Special attention is paid to the transport theory, since the physical picture depends heavily on the kind of electron collisions which dominate. This is due to the velocity dependence of collision frequencies, which gives rise to the thermal forces

Asteroid rotation. I - Tabulation and analysis of rates, pole positions and shapes. II - A theory for the collisional evolution of rotation rates

NASA Technical Reports Server (NTRS)

Harris, A. W.; Burns, J. A.

1979-01-01

Rotation properties and shape data for 182 asteroids are compiled and analyzed, and a collisional model for the evolution of the mean rotation rate of asteroids is proposed. Tabulations of asteroid rotation rates, taxonomic types, pole positions, sizes and shapes and plots of rotation frequency and light curve amplitude against size indicate that asteroid rotational frequency increases with decreasing size for all asteroids except those of the C or S classes. Light curve data also indicate that small asteroids are more irregular in shape than large asteroids. The dispersion in rotation rates observed is well represented by a three dimensional Maxwellian distribution, suggestive of collisional encounters between asteroids. In the proposed model, the rotation rate is found to tend toward an equilibrium value, at which spin-up due to infrequent, large collisions is balanced by a drag due to the larger number of small collisions. The lower mean rotation rate of C-type asteroids is attributed to a lower means density of that class, and the increase in rotation rate with decreasing size is interpreted as indicative of a substantial population of strong asteroids.

Discrete Kinetic Eigenmode Spectra of Electron Plasma Oscillations in Weakly Collisional Plasma: A Numerical Study

NASA Technical Reports Server (NTRS)

Black, Carrie; Germaschewski, Kai; Bhattacharjee, Amitava; Ng, C. S.

2013-01-01

It has been demonstrated that in the presence of weak collisions, described by the Lenard-Bernstein collision operator, the Landau-damped solutions become true eigenmodes of the system and constitute a complete set. We present numerical results from an Eulerian Vlasov code that incorporates the Lenard-Bernstein collision operator. The effect of the collisions on the numerical recursion phenomenon seen in Vlasov codes is discussed. The code is benchmarked against exact linear eigenmode solutions in the presence of weak collisions, and a spectrum of Landau-damped solutions is determined within the limits of numerical resolution. Tests of the orthogonality and the completeness relation are presented.

Do Young Drivers Become Safer After Being Involved in a Collision?

PubMed Central

O’Brien, Fearghal; Bible, Joe; Liu, Danping; Simons-Morton, Bruce G.

2017-01-01

As drivers age, their risk of being involved in a car collision decreases. The present study investigated if this trend is due, in part, to some risky drivers having a collision early in their driving lives and subsequently reducing their risky driving after that negative experience. Accelerometers and video cameras were installed in the vehicles of 16- to 17-year-old drivers (N = 254), allowing coders to measure the number of g-force events (i.e., events in which a threshold acceleration level was exceeded) per 1,000 miles and the number of collisions. Among the 41 participants who experienced a severe collision, the rate of g-force events dropped significantly in the 1st month after the collision, remained unchanged for the 2nd month, and increased significantly in the 3rd month. There were no changes in the rate of g-force events at comparable time points for the drivers not involved in a collision. Being involved in a collision led to a decrease in risky driving, but this may have been a temporary effect. PMID:28406372

Defining acute aortic syndrome after trauma: Are Abbreviated Injury Scale codes a useful surrogate descriptor?

PubMed

Leach, R; McNally, Donal; Bashir, Mohamad; Sastry, Priya; Cuerden, Richard; Richens, David; Field, Mark

2012-10-01

The severity and location of injuries resulting from vehicular collisions are normally recorded in Abbreviated Injury Scale (AIS) code; we propose a system to link AIS code to a description of acute aortic syndrome (AAS), thus allowing the hypothesis that aortic injury is progressive with collision kinematics to be tested. Standard AIS codes were matched with a clinical description of AAS. A total of 199 collisions that resulted in aortic injury were extracted from a national automotive collision database and the outcomes mapped onto AAS descriptions. The severity of aortic injury (AIS severity score) and stage of AAS progression were compared with collision kinematics and occupant demographics. Post hoc power analyses were used to estimate maximum effect size. The general demographic distribution of the sample represented that of the UK population in regard to sex and age. No significant relationship was observed between estimated test speed, collision direction, occupant location or seat belt use and clinical progression of aortic injury (once initiated). Power analysis confirmed that a suitable sample size was used to observe a medium effect in most of the cases. Similarly, no association was observed between injury severity and collision kinematics. There is sufficient information on AIS severity and location codes to map onto the clinical AAS spectrum. It was not possible, with this data set, to consider the influence of collision kinematics on aortic injury initiation. However, it was demonstrated that after initiation, further progression along the AAS pathway was not influenced by collision kinematics. This might be because the injury is not progressive, because the vehicle kinematics studied do not fully represent the kinematics of the occupants, or because an unknown factor, such as stage of cardiac cycle, dominates. Epidemiologic/prognostic study, level IV.

Energy levels, radiative rates and electron impact excitation rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV

NASA Astrophysics Data System (ADS)

Aggarwal, Kanti M.; Keenan, Francis P.

2013-04-01

We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths, and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Additionally, theoretical lifetimes are provided for all 49 levels of the above five ions. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 108 K. Comparisons are made with similar data obtained using the flexible atomic code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for some forbidden transitions, are also discussed. Finally, discrepancies between the present results for effective collision strengths with the darc code and earlier semi-relativistic R-matrix data are noted over a wide range of electron temperatures for many transitions in all ions.

Magnetic field effect on charmonium formation in high energy nuclear collisions

DOE PAGES

Guo, Xingyu; Shi, Shuzhe; Xu, Nu; ...

2015-10-23

It is important to understand the strong external magnetic field generated at the very beginning of heavy ion collisions. We study the effect of the magnetic field on the anisotropic charmonium formation in Pb + Pb collisions at the LHC energy. The time dependent Schrödinger equation is employed to describe the motion ofmore » $$c\\bar{c}$$ pairs. We compare our model prediction of the non-collective anisotropic parameter v 2 of J/ψ with CMS data at high transverse momentum.« less

Small collision systems: Theory overview on cold nuclear matter effects

NASA Astrophysics Data System (ADS)

Armesto, Néstor

2018-02-01

Many observables measured at the Relativistic Heavy Ion Collider and the Large Hadron Collider show a smooth transition between proton-proton and protonnucleus collisions (small systems), and nucleus-nucleus collisions (large systems), when represented versus some variable like the multiplicity in the event. In this contribution I review some of the physics mechanisms, named cold nuclear matter effects, that may lead to a collective-like behaviour in small systems beyond the macroscopic description provided by relativistic hydrodynamics. I focus on the nuclear modification of parton densities, single inclusive particle production and correlations.

Phenomenology of anomalous chiral transports in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Huang, Xu-Guang

2018-01-01

High-energy Heavy-ion collisions can generate extremely hot quark-gluon matter and also extremely strong magnetic fields and fluid vorticity. Once coupled to chiral anomaly, the magnetic fields and fluid vorticity can induce a variety of novel transport phenomena, including the chiral magnetic effect, chiral vortical effect, etc. Some of them require the environmental violation of parity and thus provide a means to test the possible parity violation in hot strongly interacting matter. We will discuss the underlying mechanism and implications of these anomalous chiral transports in heavy-ion collisions.

Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters

NASA Astrophysics Data System (ADS)

Tran, Jonathan

Plasma turbulence and the resulting anomalous electron transport due to azimuthal current driven instabilities in Hall-effect thrusters is a promising candidate for developing predictive models for the observed anomalous transport. A theory for anomalous electron transport and current driven instabilities has been recently studied by [Lafluer et al., 2016a]. Due to the extreme cost of fully resolving the Debye length and plasma frequency, hybrid plasma simulations utilizing kinetic ions and quasi-steady state fluid electrons have long been the principle workhorse methodology for Hall-effect thruster modeling. Using a reduced dimension particle in cell simulation implemented in the Thermophysics Universal Research Framework developed by the Air Force Research Lab, we show collective electron-wave scattering due to large amplitude azimuthal fluctuations of the electric field and the plasma density. These high-frequency and short wavelength fluctuations can lead to an effective cross-field mobility many orders of magnitude larger than what is expected from classical electron-neutral momentum collisions in the low neutral density regime. We further adapt the previous study by [Lampe et al., 1971] and [Stringer, 1964] for related current driven instabilities to electric propulsion relevant mass ratios and conditions. Finally, we conduct a preliminary study of resolving this instability with a modified hybrid simulation with the hope of integration with established hybrid Hall-effect thruster simulations.

Resolved Dual-Frequency Observations of the Debris Disk Around AU Mic: Strengths of Bodies in the Collisional Cascade

NASA Astrophysics Data System (ADS)

Carter, Evan; Hughes, A. Meredith; Daley, Cail; Flaherty, Kevin; Pan, Margaret; Schlichting, Hilke; Chiang, Eugene; MacGregor, Meredith Ann; Wilner, David; Dent, Bill; Carpenter, John; Andrews, Sean; Moor, Attila; Kospal, Agnes

2018-01-01

Debris disks are hallmarks of mature planetary systems, with second-generation dust produced via collisions between pluto-like planetesimals. The vertical structure of a debris disk encodes unique information about the dynamical state of the system, particularly at millimeter wavelengths where gravitational effects dominate over the effects of stellar radiation. We present 450 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the edge-on debris disk around AU Mic, a nearby (d = 9.91 ± 0.10 pc) M1-type star. The 0.3'' angular resolution of the data allows us to spatially resolve the scale height of the disk, complementing previous observations at a wavelength of 1.3 mm. By resolving the vertical structure of the disk at these two widely-separated frequencies, we are able to spatially resolve the spectral index and study variations in the grain size distribution as a function of disk radius. The comparison of scale heights for two different wavelengths and therefore particle sizes also constrains the velocity dispersion as a function of grain size, which allows us to probe the strengths of bodies in the collisional cascade for the first time outside the Solar System.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Min; Yu, Yun; Hu, Keke

Investigating the collisions of individual metal nanoparticles (NPs) with electrodes can provide new insights into their electrocatalytic behavior, mass transport, and interactions with surfaces. Here we report a new experimental setup for studying NP collisions based on the use of carbon nanopipettes to enable monitoring multiple collision events involving the same NP captured inside the pipet cavity. A patch clamp amplifier capable of measuring pA-range currents on the microsecond time scale with a very low noise and stable background was used to record the collision transients. The analysis of current transients produced by oxidation of hydrogen peroxide at one IrOxmore » NP provided information about the origins of deactivation of catalytic NPs and the effects of various experimental conditions on the collision dynamics. Lastly, high-resolution TEM of carbon pipettes was used to attain better understanding of the NP capture and collisions.« less

Importance of non-flow in mixed-harmonic multi-particle correlations in small collision systems

DOE PAGES

Huo, Peng; Gajdosova, Katarina; Jia, Jiangyong; ...

2017-12-18

Recently CMS Collaboration measured mixed-harmonic four-particle azimuthal correlations, known as symmetric cumulants SC(n, m), in pp and p+Pb collisions, and interpreted the non-zero SC(n, m) as evidence for long-range collectivity in these small collision systems. Using the PYTHIA and HIJING models which do not have genuine long-range collectivity, we show that the CMS results, obtained with standard cumulant method, could be dominated by non-flow effects associated with jet and dijets, especially in pp collisions. We show that the non-flow effects are largely suppressed using the recently proposed subevent cumulant methods by requiring azimuthal correlation between two or more pseudorapidity ranges.more » As a result, we argue that the reanalysis of SC(n, m) using the subevent method in experiments is necessary before they can used to provide further evidences for a long-range multi-particle collectivity and constraints on theoretical models in small collision systems.« less

Study on collision resistance characteristics of the side tanks with water inside

NASA Astrophysics Data System (ADS)

Liu, Yuxi; Hu, Jinwen; Liu, Ting; Wu, Can

2018-05-01

When we evaluate the safety performance of ships against external events, one of the most important indicator is the collision resistance to which water inside the side tanks also make some contributions because of the water effect. To further analyze the interaction mechanism, different collision velocities and side tank waterlines are set for the analysis model. Results indicate the outside shell and the inner shell of the side structure significantly enhanced the collision resistance performance to a certain extension. The water effect on the failure of the outside shell is unobvious, while, it performs a great influence on the destructive reaction force of the inner shell. When the velocity of the coming bulbous bow gradually increases, the destructive reaction forces of the outside shell and the inner shell increase with a decreasing rate. Besides, water influence the collision characteristics of the inner shell a lot when the waterlines are below the upper rib of the strong frame.

Importance of non-flow in mixed-harmonic multi-particle correlations in small collision systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huo, Peng; Gajdosova, Katarina; Jia, Jiangyong

Recently CMS Collaboration measured mixed-harmonic four-particle azimuthal correlations, known as symmetric cumulants SC(n, m), in pp and p+Pb collisions, and interpreted the non-zero SC(n, m) as evidence for long-range collectivity in these small collision systems. Using the PYTHIA and HIJING models which do not have genuine long-range collectivity, we show that the CMS results, obtained with standard cumulant method, could be dominated by non-flow effects associated with jet and dijets, especially in pp collisions. We show that the non-flow effects are largely suppressed using the recently proposed subevent cumulant methods by requiring azimuthal correlation between two or more pseudorapidity ranges.more » As a result, we argue that the reanalysis of SC(n, m) using the subevent method in experiments is necessary before they can used to provide further evidences for a long-range multi-particle collectivity and constraints on theoretical models in small collision systems.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leitner, Peter; Heyn, Martin F.; Kernbichler, Winfried

In this paper, the impact of momentum and energy conservation of the collision operator in the kinetic description for Resonant Magnetic Perturbations (RMPs) in a tokamak is studied. The particle conserving differential collision operator of Ornstein-Uhlenbeck type is supplemented with integral parts such that energy and momentum are conserved. The application to RMP penetration in a tokamak shows that energy conservation in the electron collision operator is important for the quantitative description of plasma shielding effects at the resonant surface. On the other hand, momentum conservation in the ion collision operator does not significantly change the results.

Nuclear modification factor RCP for φ meson production in d+Au collisions at √SNN=200 GeV measured by the PHENIX experiment at RHIC

NASA Astrophysics Data System (ADS)

Guo, Lei

2009-10-01

In d+Au collisions, vector mesons produced in hard scattering are sensitive to various nuclear effects such as parton shadowing/saturation in the small x region (forward rapidity) leading to suppression, and antishadowing (large x region, backward rapidity) or the Cronin effect which both can produce enhancement. Since approaches such as the Color Glass Condensate (CGC) and pQCD-based Glauber-Eikonal models do not agree on the nature of these nuclear effects on particle production at large rapidity, it is essential that they be tested with experimental data in this kinematic regime. Knowledge of the difference between the forward and backward rapidity regions, in d+Au collisions, could also be used to separate the initial-state nuclear wave function modifications and final state in-medium effects in Au+Au collisions. In addition, the relative ratio for the production of ρ, φ and φ can provide information on the production mechanisms of light vector mesons. The PHENIX collaboration at RHIC has recently collected data in d+Au collisions at √s=200 GeV during the 2008 run. The latest work on the RCP measurements of φ, through the di-muon decays at forward and backward rapidities (1.2<η<2.2), will be discussed.

Directed flow in asymmetric nucleus-nucleus collisions and the inverse Landau-Pomeranchuk-Migdal effect

NASA Astrophysics Data System (ADS)

Toneev, V. D.; Voronyuk, V.; Kolomeitsev, E. E.; Cassing, W.

2017-03-01

It is proposed to identify a strong electric field—created during relativistic collisions of asymmetric nuclei—via the observation of pseudorapidity and transverse momentum distributions of hadrons with the same mass but opposite charge. The results of detailed calculations within the parton-hadron string dynamics (PHSD) approach for the charge-dependent directed flow v1 are presented for semicentral Cu+Au collision at √{sN N}=200 GeV incorporating the inverse Landau-Pomeranchuk-Migdal (iLPM) effect, which accounts for a delay in the electromagnetic interaction with the charged degrees of freedom. By including the iLPM effect, we achieve a reasonable agreement of the PHSD results for the charge splitting in v1(pT) in line with the recent measurements by the STAR Collaboration for Cu+Au collisions at √{sN N}=200 GeV while an instant appearance and coupling of electric charges at the hard collision vertex overestimates the splitting by about a factor of 10. We predict that the iLPM effect should practically disappear at energies of √{sN N}≈ 9 GeV, which should lead to a significantly larger charge splitting of v1 at the future FAIR/NICA facilities.

Ion-neutral potential models in atmospheric pressure ion mobility time-of-flight mass spectrometry IM(tof)MS.

PubMed

Steiner, Wes E; English, William A; Hill, Herbert H

2006-02-09

The ion mobilities and their respective masses of several classes of amines (primary, secondary, and tertiary) were measured by electrospray ionization atmospheric pressure ion mobility time-of-flight mass spectrometry IM(tof)MS. The experimental data obtained were comparatively analyzed by the one-temperature kinetic theory of Chapman-Enskog. Several theoretical models were used to estimate the collision cross-sections; they include the rigid-sphere, polarization-limit, 12-6-4, and 12-4 potential models. These models were investigated to represent the interaction potentials contained within the collision integral that occurs between the polyatomic ions and the neutral drift gas molecules. The effectiveness of these collision cross-section models on predicting the mobility of these amine ions was explored. Moreover, the effects of drift gas selectivity on the reduced-mass term and in the collision cross-section term was examined. Use of a series of drift gases, namely, helium, neon, argon, nitrogen, and carbon dioxide, made it possible to distinguish between mass effects and polarizability effects. It was found that the modified 12-4 potential that compensates for the center of charge not being at the same location as the centers of mass showed improved agreement over the other collision cross-section models with respect to experimental data.

Collision-avoidance behaviors of minimally restrained flying locusts to looming stimuli

PubMed Central

Chan, R. WM.; Gabbiani, F.

2013-01-01

SUMMARY Visually guided collision avoidance is of paramount importance in flight, for instance to allow escape from potential predators. Yet, little is known about the types of collision-avoidance behaviors that may be generated by flying animals in response to an impending visual threat. We studied the behavior of minimally restrained locusts flying in a wind tunnel as they were subjected to looming stimuli presented to the side of the animal, simulating the approach of an object on a collision course. Using high-speed movie recordings, we observed a wide variety of collision-avoidance behaviors including climbs and dives away from – but also towards – the stimulus. In a more restrained setting, we were able to relate kinematic parameters of the flapping wings with yaw changes in the trajectory of the animal. Asymmetric wing flapping was most strongly correlated with changes in yaw, but we also observed a substantial effect of wing deformations. Additionally, the effect of wing deformations on yaw was relatively independent of that of wing asymmetries. Thus, flying locusts exhibit a rich range of collision-avoidance behaviors that depend on several distinct aerodynamic characteristics of wing flapping flight. PMID:23364572

The effect on collisions with injuries of a reduction in traffic citations issued by police officers.

PubMed

Blais, Etienne; Gagné, Marie-Pier

2010-12-01

To assess the effect on collisions with injuries of a 61% reduction in the number of traffic citations issued by police officers over a 21-month period. Using descriptive analyses as well as ARIMA intervention time-series analyses, this study estimated the impact of this reduction in citations issued for traffic violations on the monthly number of collisions with injuries. Simple descriptive analysis reveals that the 61% reduction in the number of citations issued for traffic violations during the experimental period coincided with an increase in collisions with injuries. Results from the interrupted time-series analyses reveal that, on average, eight additional collisions with injuries occurred every month during which the number of tickets issued for traffic violations was lower than normal. As this pressure tactic was applied for 21 months, it is estimated that this situation was associated with approximately 184 additional collisions with injuries: equivalent to 239 traffic injuries (either deaths, minor or serious injuries). In the province of Quebec, police officers are an important component of road safety policy. Issuing citations prevents drivers from adopting reckless driving habits such as speeding, running red lights and failing to fasten their seat belt.

Pion Condensation by Rotation in a Magnetic Field

NASA Astrophysics Data System (ADS)

Liu, Yizhuang; Zahed, Ismail

2018-01-01

We show that the combined effects of a rotation plus a magnetic field can cause charged pion condensation. We suggest that this phenomenon may yield to observable effects in current heavy ion collisions at collider energies, where large magnetism and rotations are expected in off-central collisions.

Predicting Space Weather Effects on Close Approach Events

NASA Technical Reports Server (NTRS)

Hejduk, Matthew D.; Newman, Lauri K.; Besser, Rebecca L.; Pachura, Daniel A.

2015-01-01

The NASA Robotic Conjunction Assessment Risk Analysis (CARA) team sends ephemeris data to the Joint Space Operations Center (JSpOC) for conjunction assessment screening against the JSpOC high accuracy catalog and then assesses risk posed to protected assets from predicted close approaches. Since most spacecraft supported by the CARA team are located in LEO orbits, atmospheric drag is the primary source of state estimate uncertainty. Drag magnitude and uncertainty is directly governed by atmospheric density and thus space weather. At present the actual effect of space weather on atmospheric density cannot be accurately predicted because most atmospheric density models are empirical in nature, which do not perform well in prediction. The Jacchia-Bowman-HASDM 2009 (JBH09) atmospheric density model used at the JSpOC employs a solar storm active compensation feature that predicts storm sizes and arrival times and thus the resulting neutral density alterations. With this feature, estimation errors can occur in either direction (i.e., over- or under-estimation of density and thus drag). Although the exact effect of a solar storm on atmospheric drag cannot be determined, one can explore the effects of JBH09 model error on conjuncting objects' trajectories to determine if a conjunction is likely to become riskier, less risky, or pass unaffected. The CARA team has constructed a Space Weather Trade-Space tool that systematically alters the drag situation for the conjuncting objects and recalculates the probability of collision for each case to determine the range of possible effects on the collision risk. In addition to a review of the theory and the particulars of the tool, the different types of observed output will be explained, along with statistics of their frequency.

A 3He-129Xe co-magnetometer probed by a Rb magnetometer with Ramsey-pulse technique

NASA Astrophysics Data System (ADS)

Sheng, Dong; Kabcenell, Aaron; Romalis, Michael

2013-05-01

We report the recent progress in development of a new kind of co-magnetometer, benifiting from both the long spin coherence time of a noble gas and a highly sensitive alkali metal magnetometer. Due to the Fermi-contact interaction between alkali metal electron spin and noble gas nuclear spin the effective magnetization of the noble gas is enhanced by a factor of 6 to 600, allowing near quantum-limited detection of nuclear spins. Collisions between polarized alkali atoms and noble gas also introduce a large shift to the nuclear spin precession frequency. We reduce this effect by using Ramsey pulse techniques to measure the noble gas spin precession frequency ``in the dark'' by turning off the pumping laser between Ramsey pulses. A furthur reduction of the back-hyperpolarization from the noble gas can be achieved by controlling the cell temperature on short time scale. We showed that a 3He-129Xe Ramsey co-magnetometer is effective in cancelling fluctuations of external magnetic fields and gradients and developed cells with sufficient 129Xe T2 time without surface coatings. The new co-magnetometer has potential applications for many precision measurements, such as searches for spin-gravity couplings, electric dipole moments, and nuclear spin gyroscopes. Supported by DARPA.

Threshold collision-induced dissociation of diatomic molecules: a case study of the energetics and dynamics of O2- collisions with Ar and Xe.

PubMed

Ahu Akin, F; Ree, Jongbaik; Ervin, Kent M; Kyu Shin, Hyung

2005-08-08

The energetics and dynamics of collision-induced dissociation of O2- with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O2- bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of ArXe to the molecular axis of O2-, while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects.

Collision warning and avoidance considerations for the Space Shuttle and Space Station Freedom

NASA Technical Reports Server (NTRS)

Vilas, Faith; Collins, Michael F.; Kramer, Paul C.; Arndt, G. Dickey; Suddath, Jerry H.

1990-01-01

The increasing hazard of manmade debris in low earth orbit (LEO) has focused attention on the requirement for collision detection, warning and avoidance systems to be developed in order to protect manned (and unmanned) spacecraft. With the number of debris objects expected to be increasing with time, the impact hazard will also be increasing. The safety of the Space Shuttle and the Space Station Freedom from destructive or catastrophic collision resulting from the hypervelocity impact of a LEO object is of increasing concern to NASA. A number of approaches to this problem are in effect or under development. The collision avoidance procedures now in effect for the Shuttle are described, and detection and avoidance procedures presently being developed at the Johnson Space Center for the Space Station Freedom are discussed.

New experimental constrains on chiral magnetic effect using charge-dependent azimuthal correlation in pPb and PbPb collisions at the LHC

NASA Astrophysics Data System (ADS)

Tu, Zhoudunming

2018-01-01

Studies of charge-dependent azimuthal correlations for the same- and oppositesign particle pairs are presented in PbPb collisions at 5 TeV and pPb collisions at 5 and 8.16 TeV, with the CMS experiment at the LHC. The azimuthal correlations are evaluated with respect to the second- and also higher-order event planes, as a function of particle pseudorapidity and transverse momentum, and event multiplicity. By employing an event-shape engineering technique, the dependence of correlations on azimuthal anisotropy flow is investigated. Results presented provide new insights to the origin of observed charge-dependent azimuthal correlations, and have important implications to the search for the chiral magnetic effect in heavy ion collisions.

Nuclear matter effects on J /ψ production in asymmetric Cu + Au collisions at √{sNN}=200 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.; Aramaki, Y.; 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.; Bing, X.; 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.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Do, J. H.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Engelmore, T.; Enokizono, A.; En'yo, H.; 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.; 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.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Hashimoto, K.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; 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, E.; 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.; Kihara, K.; Kijima, K. M.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.-J.; Kim, H.-J.; Kim, M.; Kim, Y.-J.; Kim, Y. K.; Kistenev, E.; 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. 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.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; 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.; Nouicer, R.; Novak, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Oide, H.; Okada, K.; Orjuela Koop, J. D.; Oskarsson, A.; Ozaki, H.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; 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.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; 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.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; 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.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Whitaker, S.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yanovich, A.; Yokkaichi, S.; Yoon, I.; You, Z.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Phenix Collaboration

2014-12-01

We report on J /ψ production from asymmetric Cu + Au heavy-ion collisions at √{sNN}=200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J /ψ yields in Cu + Au collisions in the Au-going direction is found to be comparable to that in Au + Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J /ψ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in the larger Au nucleus.

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.

Detection of Orbital Debris Collision Risks for the Automated Transfer Vehicle

NASA Technical Reports Server (NTRS)

Peret, L.; Legendre, P.; Delavault, S.; Martin, T.

2007-01-01

In this paper, we present a general collision risk assessment method, which has been applied through numerical simulations to the Automated Transfer Vehicle (ATV) case. During ATV ascent towards the International Space Station, close approaches between the ATV and objects of the USSTRACOM catalog will be monitored through collision rosk assessment. Usually, collision risk assessment relies on an exclusion volume or a probability threshold method. Probability methods are more effective than exclusion volumes but require accurate covariance data. In this work, we propose to use a criterion defined by an adaptive exclusion area. This criterion does not require any probability calculation but is more effective than exclusion volume methods as demonstrated by our numerical experiments. The results of these studies, when confirmed and finalized, will be used for the ATV operations.

Relativistic longitudinal self-compression of ultrashort time-domain hollow Gaussian pulses in plasma

NASA Astrophysics Data System (ADS)

Cao, Xiaochao; Fang, Feiyun; Wang, Zhaoying; Lin, Qiang

2017-10-01

We report a study on dynamical evolution of the ultrashort time-domain dark hollow Gaussian (TDHG) pulses beyond the slowly varying envelope approximation in homogenous plasma. Using the complex-source-point model, an analytical formula is proposed for describing TDHG pulses based on the oscillating electric dipoles, which is the exact solution of the Maxwell's equations. The numerical simulations show the relativistic longitudinal self-compression (RSC) due to the relativistic mass variation of moving electrons. The influences of plasma oscillation frequency and collision effect on dynamics of the TDHG pulses in plasma have been considered. Furthermore, we analyze the evolution of instantaneous energy density of the TDHG pulses on axis as well as the off axis condition.

Cascaded interactions between Raman induced solitons and dispersive waves in photonic crystal fibers at the advanced stage of supercontinuum generation.

PubMed

Driben, Rodislav; Mitschke, Fedor; Zhavoronkov, Nickolai

2010-12-06

The complex mechanism of multiple interactions between solitary and dispersive waves at the advanced stage of supercontinuum generation in photonic crystal fiber is studied in experiment and numerical simulations. Injection of high power negatively chirped pulses near zero dispersion frequency results in an effective soliton fission process with multiple interactions between red shifted Raman solitons and dispersive waves. These interactions may result in relative acceleration of solitons with further collisions between them of quasi-elastic or quasi-plastic kinds. In the spectral domain these processes result in enhancement of certain wavelength regions within the spectrum or development of a new significant band at the long wavelength side of the spectrum.

Collective modes of a two-dimensional spin-1/2 Fermi gas in a harmonic trap

NASA Astrophysics Data System (ADS)

Baur, Stefan K.; Vogt, Enrico; Köhl, Michael; Bruun, Georg M.

2013-04-01

We derive analytical expressions for the frequency and damping of the lowest collective modes of a two-dimensional Fermi gas using kinetic theory. For strong coupling, we furthermore show that pairing correlations overcompensate the effects of Pauli blocking on the collision rate for a large range of temperatures, resulting in a rate which is larger than that of a classical gas. Our results agree well with experimental data, and they recover the observed crossover from collisionless to hydrodynamic behavior with increasing coupling for the quadruple mode. Finally, we show that a trap anisotropy within the experimental bounds results in a damping of the breathing mode which is comparable to what is observed, even for a scale-invariant system.

Study on statistical breakdown delay time in argon gas using a W-band millimeter-wave gyrotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dongsung; Yu, Dongho; Choe, MunSeok

2016-04-15

In this study, we investigated plasma initiation delay times for argon volume breakdown at the W-band frequency regime. The threshold electric field is defined as the minimum electric field amplitude needed for plasma breakdown at various pressures. The measured statistical delay time showed an excellent agreement with the theoretical Gaussian distribution and the theoretically estimated formative delay time. Also, we demonstrated that the normalized effective electric field as a function of the product of pressure and formative time shows an outstanding agreement to that of 1D particle-in-cell simulation coupled with a Monte Carlo collision model [H. C. Kim and J.more » P. Verboncoeur, Phys. Plasmas 13, 123506 (2006)].« less

Dissipation of ionospheric irregularities by wave-particle and collisional interactions

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Pongratz, M. B.; Gray, S. P.; Thomsen, M. F.

1982-01-01

The nonlinear dissipation of plasma irregularities aligned parallel to an ambient magnetic field is studied numerically using a model which employs both wave-particle and collisional diffusion. A wave-particle diffusion coefficient derived from a local theory of the universal drift instability is used. This coefficient is effective in regions of nonzero plasma gradients and produces triangular-shaped irregularities with spectra which vary as f to the -4th, where f is the spatial frequency. Collisional diffusion acts rapidly on the vertices of the irregularities to reduce their amplitude. The simultaneous action of the two dissipative processes is more efficient than collisions acting alone. In this model, wave-particle diffusion mimics the forward cascade process of wave-wave coupling.

D-region differential-phase measurements and ionization variability studies

NASA Technical Reports Server (NTRS)

Weiland, R. M.; Bowhill, S. A.

1978-01-01

Measurements of electron densities in the D region are made by the partial-reflection differential-absorption and differential-phase techniques. The differential-phase data are obtained by a hard-wired phase-measuring system. Electron-sensity profiles obtained by the two techniques on six occasions are plotted and compared. Electron-density profiles obtained at the same time on 30 occasions during the years 1975 through 1977 are averaged to form a single profile for each technique. The effect of varying the assumed collision-frequency profile on these averaged profiles is studied. Time series of D-region electron-sensity data obtained by 3.4 minute intervals on six days during the summer of 1977 are examined for wave-like disturbances and tidal oscillations.

Charge-dependent azimuthal correlations in pPb collisions with CMS experiment

NASA Astrophysics Data System (ADS)

Tu, Zhoudunming; CMS Collaboration

2017-11-01

Charge-dependent azimuthal correlations relative to the event plane in AA collisions have been suggested as providing evidence for the chiral magnetic effect (CME) caused by local strong parity violation. However, the observation of the CME remains inconclusive because of several possible sources of background correlations that may account for part or all of the observed signals. This talk will present the first application of three-particle, charge-dependent azimuthal correlation analysis in proton-nucleus collisions, using pPb data collected with the CMS experiment at the LHC at √{sNN} = 5.02 TeV. The differences found in comparing same and opposite sign correlations are studied as a function of event multiplicity and the pseudorapidity gap between two of the particles detected in the CMS tracker detector. After selecting events with comparable charge-particle multiplicities, the results for pPb collisions are found to be similar to those for PbPb collisions collected at the same collision energy. With a reduced magnetic field strength and a random field orientation in high multiplicity pPb events, the CME contribution to any charge separation signal is expected to be much smaller than found in peripheral PbPb events. These results pose a challenge for the interpretation of charge-dependent azimuthal correlations in heavy ion collisions in terms of the chiral magnetic effect.

Nonlinear energy transfer and current sheet development in localized Alfvén wavepacket collisions in the strong turbulence limit

NASA Astrophysics Data System (ADS)

Verniero, J. L.; Howes, G. G.; Klein, K. G.

2018-02-01

In space and astrophysical plasmas, turbulence is responsible for transferring energy from large scales driven by violent events or instabilities, to smaller scales where turbulent energy is ultimately converted into plasma heat by dissipative mechanisms. The nonlinear interaction between counterpropagating Alfvén waves, denoted Alfvén wave collisions, drives this turbulent energy cascade, as recognized by early work with incompressible magnetohydrodynamic (MHD) equations. Recent work employing analytical calculations and nonlinear gyrokinetic simulations of Alfvén wave collisions in an idealized periodic initial state have demonstrated the key properties that strong Alfvén wave collisions mediate effectively the transfer of energy to smaller perpendicular scales and self-consistently generate current sheets. For the more realistic case of the collision between two initially separated Alfvén wavepackets, we use a nonlinear gyrokinetic simulation to show here that these key properties persist: strong Alfvén wavepacket collisions indeed facilitate the perpendicular cascade of energy and give rise to current sheets. Furthermore, the evolution shows that nonlinear interactions occur only while the wavepackets overlap, followed by a clean separation of the wavepackets with straight uniform magnetic fields and the cessation of nonlinear evolution in between collisions, even in the gyrokinetic simulation presented here which resolves dispersive and kinetic effects beyond the reach of the MHD theory.

Association of main driver-dependent risk factors with the risk of causing a vehicle collision in Spain, 1990-1999.

PubMed

Lardelli-Claret, Pablo; Luna-Del-Castillo, Juan de Dios; Jiménez-Moleón, José Juan; Rueda-Domínguez, Trinidad; García-Martín, Miguel; Femia-Marzo, Pedro; Bueno-Cavanillas, Aurora

2003-08-01

To assess the strength of association of main driver-dependent risk factors with the risk of causing a collision between vehicles in Spain, from 1990 to 1999. The data for this paired-by-collision, case-control study were obtained from the Spanish Dirección General de Tráfico traffic crash database. The study included all 220284 collisions involving two or more vehicles with four or more wheels, in which only one of the drivers involved committed an infraction. Infractor drivers comprised the case group; noninfractor drivers involved in the same collision were their corresponding paired controls. All driver-dependent factors were associated with the risk of causing a collision. The highest adjusted odds ratio estimates were obtained for sleepiness (64.35; CI, 45.12-91.79), inappropriate speed (28.33; CI, 26.37-30.44), and driving under the influence of alcohol with a positive breath test (22.32; CI, 19.64-25.37). An increase in the number of years in possession of a driving license showed a protective effect, albeit the strength of the effect decreased as age increased. Our results emphasize the urgent need to implement strategies aimed mainly at controlling speeding, sleepiness, and alcohol consumption before driving-the main driver-dependent risk factors for causing a vehicle collision.

Are school zones effective? An examination of motor vehicle versus child pedestrian crashes near schools.

PubMed

Warsh, J; Rothman, L; Slater, M; Steverango, C; Howard, A

2009-08-01

To analyse the relationships between factors related to school location and motor vehicle versus child pedestrian collisions. Data on all police-reported motor vehicle collisions involving pedestrians less than 18 years of age that occurred in Toronto, Canada, between 2000 and 2005 were analysed. Geographic information systems (GIS) software was used to assess the distance of each collision relative to school location. The relationships between distance from school and collision-related factors such as temporal patterns of school travel times and crossing locations were analysed. Study data showed a total of 2717 motor vehicle versus child (<18) pedestrian collisions. The area density of collisions (collisions/area), particularly fatal collisions, was highest in school zones and decreased as distance from schools increased. The highest proportion of collisions (37.3%) occurred among 10-14-year-olds. Within school zones, collisions were more likely to occur among 5-9-year-old children as they travelled to and from school during months when school was in session. Most collisions within school zones occurred at midblock locations versus intersections. Focusing interventions around schools with attention to age, travel times, and crossing location will reduce the burden of injury in children. Future studies that take into account traffic and pedestrian volume surrounding schools would be useful for prevention efforts as well as for promotion of walking. These results will help identify priorities and emphasise the importance of considering spatial and temporal patterns in child pedestrian research.

K(892)* resonance production in Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV at RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, J.; Aggarwal, M.M.; Ahammed, Z.

2004-12-09

The short-lived K(892)* resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of K* in {radical}s{sub NN} = 200 GeV Au+Au and p+p collisions reconstructed via its hadronic decay channels K(892)*{sup 0} {yields} K{pi} and K(892)*{sup +-} {yields} K{sub S}{sup 0}{pi}{sup +-} using the STAR detector at RHIC. The K*{sup 0} mass has been studied as function of p{sub T} in minimum bias p + p and central Au+Au collisions. The K* p{sub T} spectra for minimum bias p + p interactions and for Au+Au collisions inmore » different centralities are presented. The K*/K ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias p + p collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. The nuclear modification factor of K* at intermediate p{sub T} is similar to that of K{sub S}{sup 0}, but different from {Lambda}. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate p{sub T} (2 < p{sub T} {le} 4 GeV/c). A significant non-zero K*{sup 0} elliptic flow (v{sub 2}) is observed in Au+Au collisions and compared to the K{sub S}{sup 0} and {Lambda} v{sub 2}.« less

Collision recognition and direction changes for small scale fish robots by acceleration sensors

NASA Astrophysics Data System (ADS)

Na, Seung Y.; Shin, Daejung; Kim, Jin Y.; Lee, Bae-Ho

2005-05-01

Typical obstacles are walls, rocks, water plants and other nearby robots for a group of small scale fish robots and submersibles that have been constructed in our lab. Sonar sensors are not employed to make the robot structure simple enough. All of circuits, sensors and processor cards are contained in a box of 9 x 7 x 4 cm dimension except motors, fins and external covers. Therefore, image processing results are applied to avoid collisions. However, it is useful only when the obstacles are located far enough to give images processing time for detecting them. Otherwise, acceleration sensors are used to detect collision immediately after it happens. Two of 2-axes acceleration sensors are employed to measure the three components of collision angles, collision magnitudes, and the angles of robot propulsion. These data are integrated to calculate the amount of propulsion direction change. The angle of a collision incident upon an obstacle is the fundamental value to obtain a direction change needed to design a following path. But there is a significant amount of noise due to a caudal fin motor. Because caudal fin provides the main propulsion for a fish robot, there is a periodic swinging noise at the head of a robot. This noise provides a random acceleration effect on the measured acceleration data at the collision. We propose an algorithm which shows that the MEMS-type accelerometers are very effective to provide information for direction changes in spite of the intrinsic noise after the small scale fish robots have made obstacle collision.

On RF heating of inhomogeneous collisional plasma under ion-cyclotron resonance conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timofeev, A. V., E-mail: Timofeev-AV@nrcki.ru

2015-11-15

During ion-cyclotron resonance (ICR) heating of plasma by the magnetic beach method, as well as in some other versions of ICR heating, it is necessary to excite Alfvén oscillations. In this case, it is difficult to avoid the phenomenon of the Alfvén resonance, in which Alfvén oscillations transform into lower hybrid oscillations. The latter efficiently interact with electrons, due to which most of the deposited RF energy is spent on electron (rather than ion) heating. The Alfvén resonance takes place due to plasma inhomogeneity across the external magnetic field. Therefore, it could be expected that variations in the plasma densitymore » profile would substantially affect the efficiency of the interaction of RF fields with charged particles. However, the results obtained for different plasma density profiles proved to be nearly the same. In the present work, a plasma is considered the parameters of which correspond to those planned in future ICR plasma heating experiments on the PS-1 facility at the Kurchatov Institute. When analyzing the interaction of RF fields with charged particles, both the collisionless resonance interaction and the interaction caused by Coulomb collisions are taken into account, because, in those experiments, the Coulomb collision frequency will be comparable with the frequency of the heating field. Antennas used for ICR heating excite RF oscillations with a wide spectrum of wavenumbers along the magnetic field. After averaging over the spectrum, the absorbed RF energy calculated with allowance for collisions turns out to be close to that absorbed in collisionless plasma, the energy fraction absorbed by electrons being substantially larger than that absorbed by ions.« less