WorldWideScience

Sample records for outflow simulated average

  1. Simulation of Breach Outflow for Earthfill Dam

    International Nuclear Information System (INIS)

    Razad, Azwin Zailti Abdul; Muda, Rahsidi Sabri; Sidek, Lariyah Mohd; Azia, Intan Shafilah Abdul; Mansor, Faezah Hanum; Yalit, Ruzaimei

    2013-01-01

    Dams have been built for many reasons such as irrigation, hydropower, flood mitigation, and water supply to support development for the benefit of human. However, the huge amount of water stored behind the dam can seriously pose adverse impacts to the downstream community should it be released due to unwanted dam break event. To minimise the potential loss of lives and property damages, a workable Emergency Response Plan is required to be developed. As part of a responsible dam owner and operator, TNB initiated a study on dam breach modelling for Cameron Highlands Hydroelectric Scheme to simulate the potential dam breach for Jor Dam. Prediction of dam breach parameters using the empirical equations of Froehlich and Macdonal-Langridge-Monopolis formed the basis of the modelling, coupled with MIKE 11 software to obtain the breach outflow due to Probable Maximum Flood (PMF). This paper will therefore discuss the model setup, simulation procedure and comparison of the prediction with existing equations.

  2. Simulation of California's Major Reservoirs Outflow Using Data Mining Technique

    Science.gov (United States)

    Yang, T.; Gao, X.; Sorooshian, S.

    2014-12-01

    The reservoir's outflow is controlled by reservoir operators, which is different from the upstream inflow. The outflow is more important than the reservoir's inflow for the downstream water users. In order to simulate the complicated reservoir operation and extract the outflow decision making patterns for California's 12 major reservoirs, we build a data-driven, computer-based ("artificial intelligent") reservoir decision making tool, using decision regression and classification tree approach. This is a well-developed statistical and graphical modeling methodology in the field of data mining. A shuffled cross validation approach is also employed to extract the outflow decision making patterns and rules based on the selected decision variables (inflow amount, precipitation, timing, water type year etc.). To show the accuracy of the model, a verification study is carried out comparing the model-generated outflow decisions ("artificial intelligent" decisions) with that made by reservoir operators (human decisions). The simulation results show that the machine-generated outflow decisions are very similar to the real reservoir operators' decisions. This conclusion is based on statistical evaluations using the Nash-Sutcliffe test. The proposed model is able to detect the most influential variables and their weights when the reservoir operators make an outflow decision. While the proposed approach was firstly applied and tested on California's 12 major reservoirs, the method is universally adaptable to other reservoir systems.

  3. Better Than Nothing: A Rational Approach for Minimizing the Impact of Outflow Strategy on Cerebrovascular Simulations.

    Science.gov (United States)

    Chnafa, C; Brina, O; Pereira, V M; Steinman, D A

    2018-02-01

    Computational fluid dynamics simulations of neurovascular diseases are impacted by various modeling assumptions and uncertainties, including outlet boundary conditions. Many studies of intracranial aneurysms, for example, assume zero pressure at all outlets, often the default ("do-nothing") strategy, with no physiological basis. Others divide outflow according to the outlet diameters cubed, nominally based on the more physiological Murray's law but still susceptible to subjective choices about the segmented model extent. Here we demonstrate the limitations and impact of these outflow strategies, against a novel "splitting" method introduced here. With our method, the segmented lumen is split into its constituent bifurcations, where flow divisions are estimated locally using a power law. Together these provide the global outflow rate boundary conditions. The impact of outflow strategy on flow rates was tested for 70 cases of MCA aneurysm with 0D simulations. The impact on hemodynamic indices used for rupture status assessment was tested for 10 cases with 3D simulations. Differences in flow rates among the various strategies were up to 70%, with a non-negligible impact on average and oscillatory wall shear stresses in some cases. Murray-law and splitting methods gave flow rates closest to physiological values reported in the literature; however, only the splitting method was insensitive to arbitrary truncation of the model extent. Cerebrovascular simulations can depend strongly on the outflow strategy. The default zero-pressure method should be avoided in favor of Murray-law or splitting methods, the latter being released as an open-source tool to encourage the standardization of outflow strategies. © 2018 by American Journal of Neuroradiology.

  4. Physical Processes for Driving Ionospheric Outflows in Global Simulations

    Science.gov (United States)

    Moore, Thomas Earle; Strangeway, Robert J.

    2009-01-01

    We review and assess the importance of processes thought to drive ionospheric outflows, linking them as appropriate to the solar wind and interplanetary magnetic field, and to the spatial and temporal distribution of their magnetospheric internal responses. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitating particles. Observations and simulations show that solar wind energy dissipation into the atmosphere is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma, neutral gas and by extension, the entire body " We assess the Importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multispecies global simulation codes. We complete 'he survey with an assessment of outstanding obstacles to this objective.

  5. Monte Carlo Simulations of Photospheric Emission in Relativistic Outflows

    Science.gov (United States)

    Bhattacharya, Mukul; Lu, Wenbin; Kumar, Pawan; Santana, Rodolfo

    2018-01-01

    We study the spectra of photospheric emission from highly relativistic gamma-ray burst outflows using a Monte Carlo code. We consider the Comptonization of photons with a fast-cooled synchrotron spectrum in a relativistic jet with a realistic photon-to-electron number ratio {N}γ /{N}{{e}}={10}5, using mono-energetic protons that interact with thermalized electrons through Coulomb interaction. The photons, electrons, and protons are cooled adiabatically as the jet expands outward. We find that the initial energy distributions of the protons and electrons do not have any appreciable effect on the photon peak energy {E}γ ,{peak} and the power-law spectrum above {E}γ ,{peak}. The Coulomb interaction between the electrons and the protons does not affect the output photon spectrum significantly as the energy of the electrons is elevated only marginally. {E}γ ,{peak} and the spectral indices for the low- and high-energy power-law tails of the photon spectrum remain practically unchanged even with electron-proton coupling. Increasing the initial optical depth {τ }{in} results in a slightly shallower photon spectrum below {E}γ ,{peak} and fewer photons at the high-energy tail, although {f}ν \\propto {ν }-0.5 above {E}γ ,{peak} and up to ∼1 MeV, independent of {τ }{in}. We find that {E}γ ,{peak} determines the peak energy and the shape of the output photon spectrum. Finally, we find that our simulation results are quite sensitive to {N}γ /{N}{{e}}, for {N}{{e}}=3× {10}3. For almost all our simulations, we obtain an output photon spectrum with a power-law tail above {E}γ ,{peak} extending up to ∼1 MeV.

  6. Reynolds averaged simulation of unsteady separated flow

    International Nuclear Information System (INIS)

    Iaccarino, G.; Ooi, A.; Durbin, P.A.; Behnia, M.

    2003-01-01

    The accuracy of Reynolds averaged Navier-Stokes (RANS) turbulence models in predicting complex flows with separation is examined. The unsteady flow around square cylinder and over a wall-mounted cube are simulated and compared with experimental data. For the cube case, none of the previously published numerical predictions obtained by steady-state RANS produced a good match with experimental data. However, evidence exists that coherent vortex shedding occurs in this flow. Its presence demands unsteady RANS computation because the flow is not statistically stationary. The present study demonstrates that unsteady RANS does indeed predict periodic shedding, and leads to much better concurrence with available experimental data than has been achieved with steady computation

  7. Figuring Out Gas and Galaxies in Enzo (FOGGIE): Simulating effects of feedback on galactic outflows

    Science.gov (United States)

    Morris, Melissa Elizabeth; Corlies, Lauren; Peeples, Molly; Tumlinson, Jason; O'Shea, Brian; Smith, Britton

    2018-01-01

    The circumgalactic medium (CGM) is the region beyond the galactic disk in which gas is accreted through pristine inflows from the intergalactic medium and expelled from the galaxy by stellar feedback in large outflows that can then be recycled back onto the disk. These gas cycles connect the galactic disk with its cosmic environment, making the CGM a vital component of galaxy evolution. However, the CGM is primarily observed in absorption, which can be difficult to interpret. In this study, we use high resolution cosmological hydrodynamic simulations of a Milky Way mass halo evolved with the code Enzo to aid the interpretation of these observations. In our simulations, we vary feedback strength and observe the effect it has on galactic outflows and the evolution of the galaxy’s CGM. We compare the star formation rate of the galaxy with the velocity flux and mass outflow rate as a function of height above the plane of the galaxy in order to measure the strength of the outflows and how far they extend outside of the galaxy.This work was supported by The Space Astronomy Summer Program at STScI and NSF grant AST-1517908.

  8. Flow splitting in numerical simulations of oceanic dense-water outflows

    Science.gov (United States)

    Marques, Gustavo M.; Wells, Mathew G.; Padman, Laurie; Özgökmen, Tamay M.

    2017-05-01

    Flow splitting occurs when part of a gravity current becomes neutrally buoyant and separates from the bottom-trapped plume as an interflow. This phenomenon has been previously observed in laboratory experiments, small-scale water bodies (e.g., lakes) and numerical studies of small-scale systems. Here, the potential for flow splitting in oceanic gravity currents is investigated using high-resolution (Δx = Δz = 5 m) two-dimensional numerical simulations of gravity flows into linearly stratified environments. The model is configured to solve the non-hydrostatic Boussinesq equations without rotation. A set of experiments is conducted by varying the initial buoyancy number B0 =Q0N3 /g‧2 (where Q0 is the volume flux of the dense water flow per unit width, N is the ambient stratification and g‧ is the reduced gravity), the bottom slope (α) and the turbulent Prandtl number (Pr). Regardless of α or Pr, when B0 ≤ 0.002 the outflow always reaches the deep ocean forming an underflow. Similarly, when B0 ≥ 0.13 the outflow always equilibrates at intermediate depths, forming an interflow. However, when B0 ∼ 0.016, flow splitting always occurs when Pr ≥ 10, while interflows always occur for Pr = 1. An important characteristic of simulations that result in flow splitting is the development of Holmboe-like interfacial instabilities and flow transition from a supercritical condition, where the Froude number (Fr) is greater than one, to a slower and more uniform subcritical condition (Fr internal hydraulic jump and consequent mixing enhancement. Although our experiments do not take into account three-dimensionality and rotation, which are likely to influence mixing and the transition between flow regimes, a comparison between our results and oceanic observations suggests that flow splitting may occur in dense-water outflows with weak ambient stratification, such as Antarctic outflows.

  9. Large interface simulation in an averaged two-fluid code

    International Nuclear Information System (INIS)

    Henriques, A.

    2006-01-01

    Different ranges of size of interfaces and eddies are involved in multiphase flow phenomena. Classical formalisms focus on a specific range of size. This study presents a Large Interface Simulation (LIS) two-fluid compressible formalism taking into account different sizes of interfaces. As in the single-phase Large Eddy Simulation, a filtering process is used to point out Large Interface (LI) simulation and Small interface (SI) modelization. The LI surface tension force is modelled adapting the well-known CSF method. The modelling of SI transfer terms is done calling for classical closure laws of the averaged approach. To simulate accurately LI transfer terms, we develop a LI recognition algorithm based on a dimensionless criterion. The LIS model is applied in a classical averaged two-fluid code. The LI transfer terms modelling and the LI recognition are validated on analytical and experimental tests. A square base basin excited by a horizontal periodic movement is studied with the LIS model. The capability of the model is also shown on the case of the break-up of a bubble in a turbulent liquid flow. The break-up of a large bubble at a grid impact performed regime transition between two different scales of interface from LI to SI and from PI to LI. (author) [fr

  10. Average accelerator simulation Truebeam using phase space in IAEA format

    International Nuclear Information System (INIS)

    Santana, Emico Ferreira; Milian, Felix Mas; Paixao, Paulo Oliveira; Costa, Raranna Alves da; Velasco, Fermin Garcia

    2015-01-01

    In this paper is used a computational code of radiation transport simulation based on Monte Carlo technique, in order to model a linear accelerator of treatment by Radiotherapy. This work is the initial step of future proposals which aim to study several treatment of patient by Radiotherapy, employing computational modeling in cooperation with the institutions UESC, IPEN, UFRJ e COI. The Chosen simulation code is GATE/Geant4. The average accelerator is TrueBeam of Varian Company. The geometric modeling was based in technical manuals, and radiation sources on the phase space for photons, provided by manufacturer in the IAEA (International Atomic Energy Agency) format. The simulations were carried out in equal conditions to experimental measurements. Were studied photons beams of 6MV, with 10 per 10 cm of field, focusing on a water phantom. For validation were compared dose curves in depth, lateral profiles in different depths of the simulated results and experimental data. The final modeling of this accelerator will be used in future works involving treatments and real patients. (author)

  11. Simulating and understanding the gap outflow and oceanic response over the Gulf of Tehuantepec during GOTEX

    Science.gov (United States)

    Hong, Xiaodong; Peng, Melinda; Wang, Shouping; Wang, Qing

    2018-06-01

    Tehuantepecer is a strong mountain gap wind traveling through Chivela Pass into eastern Pacific coast in southern Mexico, most commonly between October and February and brings huge impacts on local and surrounding meteorology and oceanography. Gulf of Tehuantepec EXperiment (GOTEX) was conducted in February 2004 to enhance the understanding of the strong offshore gap wind, ocean cooling, vertical circulations and interactions among them. The gap wind event during GOTEX was simulated using the U.S. Navy Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®). The simulations are compared and validated with the observations retrieved from several satellites (GOES 10-12, MODIS/Aqua/Terra, TMI, and QuikSCAT) and Airborne EXpendable BathyThermograph (AXBT). The study shows that the gap wind outflow has a fanlike pattern expending from the coast and with a strong diurnal variability. The surface wind stress and cooling along the axis of the gap wind outflow caused intense upwelling and vertical mixing in the upper ocean; both contributed to the cooling of the ocean mixed layer under the gap wind. The cooling pattern of sea surface temperature (SST) also reflects temperature advection by the nearby ocean eddies to have a crescent shape. Two sensitivity experiments were conducted to understand the relative roles of the wind stress and heat flux on the ocean cooling. The control has more cooling right under the gap flow region than either the wind-stress-only or the heat-flux-only experiment. Overall, the wind stress has a slightly larger effect in bringing down the ocean temperature near the surface and plays a more important role in local ocean circulations beneath the mixed layer. The impact of surface heat flux on the ocean is more limited to the top 30 m within the mixed layer and is symmetric to the gap flow region by cooling the ocean under the gap flow region and reducing the warming on both sides. The effect of surface wind stress is to induce more cooling

  12. Using NASA's Giovanni System to Simulate Time-Series Stations in the Outflow Region of California's Eel River

    Science.gov (United States)

    Acker, James G.; Shen, Suhung; Leptoukh, Gregory G.; Lee, Zhongping

    2012-01-01

    Oceanographic time-series stations provide vital data for the monitoring of oceanic processes, particularly those associated with trends over time and interannual variability. There are likely numerous locations where the establishment of a time-series station would be desirable, but for reasons of funding or logistics, such establishment may not be feasible. An alternative to an operational time-series station is monitoring of sites via remote sensing. In this study, the NASA Giovanni data system is employed to simulate the establishment of two time-series stations near the outflow region of California s Eel River, which carries a high sediment load. Previous time-series analysis of this location (Acker et al. 2009) indicated that remotely-sensed chl a exhibits a statistically significant increasing trend during summer (low flow) months, but no apparent trend during winter (high flow) months. Examination of several newly-available ocean data parameters in Giovanni, including 8-day resolution data, demonstrates the differences in ocean parameter trends at the two locations compared to regionally-averaged time-series. The hypothesis that the increased summer chl a values are related to increasing SST is evaluated, and the signature of the Eel River plume is defined with ocean optical parameters.

  13. Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

    Science.gov (United States)

    Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

    2017-12-01

    Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

  14. The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy

    Science.gov (United States)

    Danehkar, Ashkbiz; Nowak, Michael A.; Lee, Julia C.; Kriss, Gerard A.; Young, Andrew J.; Hardcastle, Martin J.; Chakravorty, Susmita; Fang, Taotao; Neilsen, Joseph; Rahoui, Farid; Smith, Randall K.

    2018-02-01

    We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create XSTAR photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately ‑17,300 km s‑1 (outflow redshift z out ∼ ‑0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter {log}ξ ∼ 2.9 {erg} {{{s}}}-1 {cm} and column density {log}{N}{{H}}∼ 21.5 {{cm}}-2. This corresponds to a stable region of the absorber’s thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately ‑16,980 km s‑1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.

  15. The origin of ultrafast outflows in AGN: Monte Carlo simulations of the wind in PDS 456

    Science.gov (United States)

    Hagino, Kouichi; Odaka, Hirokazu; Done, Chris; Gandhi, Poshak; Watanabe, Shin; Sako, Masao; Takahashi, Tadayuki

    2015-01-01

    Ultrafast outflows (UFOs) are seen in many AGN, giving a possible mode for AGN feedback on to the host galaxy. However, the mechanism(s) for the launch and acceleration of these outflows are currently unknown, with UV line driving apparently strongly disfavoured as the material along the line of sight is so highly ionized that it has no UV transitions. We revisit this issue using the Suzaku X-ray data from PDS 456, an AGN with the most powerful UFO seen in the local Universe. We explore conditions in the wind by developing a new 3D Monte Carlo code for radiation transport. The code only handles highly ionized ions, but the data show the ionization state of the wind is high enough that this is appropriate, and this restriction makes it fast enough to explore parameter space. We reproduce the results of earlier work, confirming that the mass-loss rate in the wind is around 30 per cent of the inferred inflow rate through the outer disc. We show for the first time that UV line driving is likely to be a major contribution to the wind acceleration. The mass-loss rate in the wind matches that predicted from a purely line driven system, and this UV absorption can take place out of the line of sight. Continuum driving should also play a role as the source is close to Eddington. This predicts that the most extreme outflows will be produced from the highest mass accretion rate flows on to high-mass black holes, as observed.

  16. GLOBAL STRUCTURE OF THREE DISTINCT ACCRETION FLOWS AND OUTFLOWS AROUND BLACK HOLES FROM TWO-DIMENSIONAL RADIATION-MAGNETOHYDRODYNAMIC SIMULATIONS

    International Nuclear Information System (INIS)

    Ohsuga, Ken; Mineshige, Shin

    2011-01-01

    We present the detailed global structure of black hole accretion flows and outflows through newly performed two-dimensional radiation-magnetohydrodynamic simulations. By starting from a torus threaded with weak toroidal magnetic fields and by controlling the central density of the initial torus, ρ 0 , we can reproduce three distinct modes of accretion flow. In model A, which has the highest central density, an optically and geometrically thick supercritical accretion disk is created. The radiation force greatly exceeds the gravity above the disk surface, thereby driving a strong outflow (or jet). Because of mild beaming, the apparent (isotropic) photon luminosity is ∼22L E (where L E is the Eddington luminosity) in the face-on view. Even higher apparent luminosity is feasible if we increase the flow density. In model B, which has moderate density, radiative cooling of the accretion flow is so efficient that a standard-type, cold, and geometrically thin disk is formed at radii greater than ∼7 R S (where R S is the Schwarzschild radius), while the flow is radiatively inefficient otherwise. The magnetic-pressure-driven disk wind appears in this model. In model C, the density is too low for the flow to be radiatively efficient. The flow thus becomes radiatively inefficient accretion flow, which is geometrically thick and optically thin. The magnetic-pressure force, together with the gas-pressure force, drives outflows from the disk surface, and the flow releases its energy via jets rather than via radiation. Observational implications are briefly discussed.

  17. A comparison study between observations and simulation results of Barghouthi model for O+ and H+ outflows in the polar wind

    Directory of Open Access Journals (Sweden)

    I. A. Barghouthi

    2011-11-01

    Full Text Available To advance our understanding of the effect of wave-particle interactions on ion outflows in the polar wind region and the resulting ion heating and escape from low altitudes to higher altitudes, we carried out a comparison between polar wind simulations obtained using Barghouthi model with corresponding observations obtained from different satellites. The Barghouthi model describes O+ and H+ outflows in the polar wind region in the range 1.7 RE to 13.7 RE, including the effects of gravity, polarization electrostatic field, diverging geomagnetic field lines, and wave-particle interactions. Wave-particle interactions were included into the model by using a particle diffusion equation, which depends on diffusion coefficients determined from estimates of the typical electric field spectral density at relevant altitudes and frequencies. We provide a formula for the velocity diffusion coefficient that depends on altitude and velocity, in which the velocity part depends on the perpendicular wavelength of the electromagnetic turbulence λ⊥. Because of the shortage of information about λ⊥, it was included into the model as a parameter. We produce different simulations (i.e. ion velocity distributions, ions density, ion drift velocity, ion parallel and perpendicular temperatures for O+ and H+ ions, and for different λ⊥. We discuss the simulations in terms of wave-particle interactions, perpendicular adiabatic cooling, parallel adiabatic cooling, mirror force, and ion potential energy. The main findings of the simulations are as follows: (1 O+ ions are highly energized at all altitudes in the simulation tube due to wave-particle interactions that heat the ions in the perpendicular direction, and part of this gained energy transfer to the parallel direction by mirror force, resulting in accelerating O+ ions along geomagnetic field lines from lower altitudes to higher altitudes. (2 The effect of wave-particle interactions is negligible for H

  18. Hybrid Reynolds-Averaged/Large Eddy Simulation of the Flow in a Model SCRamjet Cavity Flameholder

    Science.gov (United States)

    Baurle, R. A.

    2016-01-01

    Steady-state and scale-resolving simulations have been performed for flow in and around a model scramjet combustor flameholder. Experimental data available for this configuration include velocity statistics obtained from particle image velocimetry. Several turbulence models were used for the steady-state Reynolds-averaged simulations which included both linear and non-linear eddy viscosity models. The scale-resolving simulations used a hybrid Reynolds-averaged/large eddy simulation strategy that is designed to be a large eddy simulation everywhere except in the inner portion (log layer and below) of the boundary layer. Hence, this formulation can be regarded as a wall-modeled large eddy simulation. This e ort was undertaken to not only assess the performance of the hybrid Reynolds-averaged / large eddy simulation modeling approach in a flowfield of interest to the scramjet research community, but to also begin to understand how this capability can best be used to augment standard Reynolds-averaged simulations. The numerical errors were quantified for the steady-state simulations, and at least qualitatively assessed for the scale-resolving simulations prior to making any claims of predictive accuracy relative to the measurements. The steady-state Reynolds-averaged results displayed a high degree of variability when comparing the flameholder fuel distributions obtained from each turbulence model. This prompted the consideration of applying the higher-fidelity scale-resolving simulations as a surrogate "truth" model to calibrate the Reynolds-averaged closures in a non-reacting setting prior to their use for the combusting simulations. In general, the Reynolds-averaged velocity profile predictions at the lowest fueling level matched the particle imaging measurements almost as well as was observed for the non-reacting condition. However, the velocity field predictions proved to be more sensitive to the flameholder fueling rate than was indicated in the measurements.

  19. Hybrid Reynolds-Averaged/Large Eddy Simulation of a Cavity Flameholder; Assessment of Modeling Sensitivities

    Science.gov (United States)

    Baurle, R. A.

    2015-01-01

    Steady-state and scale-resolving simulations have been performed for flow in and around a model scramjet combustor flameholder. The cases simulated corresponded to those used to examine this flowfield experimentally using particle image velocimetry. A variety of turbulence models were used for the steady-state Reynolds-averaged simulations which included both linear and non-linear eddy viscosity models. The scale-resolving simulations used a hybrid Reynolds-averaged / large eddy simulation strategy that is designed to be a large eddy simulation everywhere except in the inner portion (log layer and below) of the boundary layer. Hence, this formulation can be regarded as a wall-modeled large eddy simulation. This effort was undertaken to formally assess the performance of the hybrid Reynolds-averaged / large eddy simulation modeling approach in a flowfield of interest to the scramjet research community. The numerical errors were quantified for both the steady-state and scale-resolving simulations prior to making any claims of predictive accuracy relative to the measurements. The steady-state Reynolds-averaged results showed a high degree of variability when comparing the predictions obtained from each turbulence model, with the non-linear eddy viscosity model (an explicit algebraic stress model) providing the most accurate prediction of the measured values. The hybrid Reynolds-averaged/large eddy simulation results were carefully scrutinized to ensure that even the coarsest grid had an acceptable level of resolution for large eddy simulation, and that the time-averaged statistics were acceptably accurate. The autocorrelation and its Fourier transform were the primary tools used for this assessment. The statistics extracted from the hybrid simulation strategy proved to be more accurate than the Reynolds-averaged results obtained using the linear eddy viscosity models. However, there was no predictive improvement noted over the results obtained from the explicit

  20. GALAXY OUTFLOWS WITHOUT SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Sur, Sharanya [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore 560034 (India); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 876004, Tempe-85287 (United States); Ostriker, Eve C., E-mail: sharanya.sur@iiap.res.in, E-mail: sharanya.sur@asu.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-02-10

    High surface density, rapidly star-forming galaxies are observed to have ≈50–100 km s{sup −1} line of sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds ≈35 km s{sup −1}, as occurs in the dense disks that have star-formation rate (SFR) densities above ≈0.1 M{sub ⊙} yr{sup −1} kpc{sup −2}. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the SFR density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from supernovae.

  1. Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Coaxial Supersonic Free-Jet Experiment

    Science.gov (United States)

    Baurle, Robert A.; Edwards, Jack R.

    2010-01-01

    Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment was designed to study compressible mixing flow phenomenon under conditions that are representative of those encountered in scramjet combustors. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The initial value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was observed when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid Reynolds-averaged/large-eddy simulations also over-predicted the mixing layer spreading rate for the helium case, while under-predicting the rate of mixing when argon was used as the injectant. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions were suggested as a remedy to this dilemma. Second-order turbulence statistics were also compared to their modeled Reynolds-averaged counterparts to evaluate the effectiveness of common turbulence closure

  2. Three-Dimensional General-Relativistic Magnetohydrodynamic Simulations of Remnant Accretion Disks from Neutron Star Mergers: Outflows and r-Process Nucleosynthesis.

    Science.gov (United States)

    Siegel, Daniel M; Metzger, Brian D

    2017-12-08

    The merger of binary neutron stars, or of a neutron star and a stellar-mass black hole, can result in the formation of a massive rotating torus around a spinning black hole. In addition to providing collimating media for γ-ray burst jets, unbound outflows from these disks are an important source of mass ejection and rapid neutron capture (r-process) nucleosynthesis. We present the first three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of neutrino-cooled accretion disks in neutron star mergers, including a realistic equation of state valid at low densities and temperatures, self-consistent evolution of the electron fraction, and neutrino cooling through an approximate leakage scheme. After initial magnetic field amplification by magnetic winding, we witness the vigorous onset of turbulence driven by the magnetorotational instability (MRI). The disk quickly reaches a balance between heating from MRI-driven turbulence and neutrino cooling, which regulates the midplane electron fraction to a low equilibrium value Y_{e}≈0.1. Over the 380-ms duration of the simulation, we find that a fraction ≈20% of the initial torus mass is unbound in powerful outflows with asymptotic velocities v≈0.1c and electron fractions Y_{e}≈0.1-0.25. Postprocessing the outflows through a nuclear reaction network shows the production of a robust second- and third-peak r process. Though broadly consistent with the results of previous axisymmetric hydrodynamical simulations, extrapolation of our results to late times suggests that the total ejecta mass from GRMHD disks is significantly higher. Our results provide strong evidence that postmerger disk outflows are an important site for the r process.

  3. Comparison of reynolds averaged navier stokes based simulation and large eddy simulation for one isothermal swirling flow

    DEFF Research Database (Denmark)

    Yang, Yang; Kær, Søren Knudsen

    2012-01-01

    The flow structure of one isothermal swirling case in the Sydney swirl flame database was studied using two numerical methods. Results from the Reynolds-averaged Navier-Stokes (RANS) approach and large eddy simulation (LES) were compared with experimental measurements. The simulations were applied...

  4. Hybrid Large-Eddy/Reynolds-Averaged Simulation of a Supersonic Cavity Using VULCAN

    Science.gov (United States)

    Quinlan, Jesse; McDaniel, James; Baurle, Robert A.

    2013-01-01

    Simulations of a supersonic recessed-cavity flow are performed using a hybrid large-eddy/Reynolds-averaged simulation approach utilizing an inflow turbulence recycling procedure and hybridized inviscid flux scheme. Calorically perfect air enters a three-dimensional domain at a free stream Mach number of 2.92. Simulations are performed to assess grid sensitivity of the solution, efficacy of the turbulence recycling, and the effect of the shock sensor used with the hybridized inviscid flux scheme. Analysis of the turbulent boundary layer upstream of the rearward-facing step for each case indicates excellent agreement with theoretical predictions. Mean velocity and pressure results are compared to Reynolds-averaged simulations and experimental data for each case and indicate good agreement on the finest grid. Simulations are repeated on a coarsened grid, and results indicate strong grid density sensitivity. Simulations are performed with and without inflow turbulence recycling on the coarse grid to isolate the effect of the recycling procedure, which is demonstrably critical to capturing the relevant shear layer dynamics. Shock sensor formulations of Ducros and Larsson are found to predict mean flow statistics equally well.

  5. A comparative analysis of 9 multi-model averaging approaches in hydrological continuous streamflow simulation

    Science.gov (United States)

    Arsenault, Richard; Gatien, Philippe; Renaud, Benoit; Brissette, François; Martel, Jean-Luc

    2015-10-01

    This study aims to test whether a weighted combination of several hydrological models can simulate flows more accurately than the models taken individually. In addition, the project attempts to identify the most efficient model averaging method and the optimal number of models to include in the weighting scheme. In order to address the first objective, streamflow was simulated using four lumped hydrological models (HSAMI, HMETS, MOHYSE and GR4J-6), each of which were calibrated with three different objective functions on 429 watersheds. The resulting 12 hydrographs (4 models × 3 metrics) were weighted and combined with the help of 9 averaging methods which are the simple arithmetic mean (SAM), Akaike information criterion (AICA), Bates-Granger (BGA), Bayes information criterion (BICA), Bayesian model averaging (BMA), Granger-Ramanathan average variant A, B and C (GRA, GRB and GRC) and the average by SCE-UA optimization (SCA). The same weights were then applied to the hydrographs in validation mode, and the Nash-Sutcliffe Efficiency metric was measured between the averaged and observed hydrographs. Statistical analyses were performed to compare the accuracy of weighted methods to that of individual models. A Kruskal-Wallis test and a multi-objective optimization algorithm were then used to identify the most efficient weighted method and the optimal number of models to integrate. Results suggest that the GRA, GRB, GRC and SCA weighted methods perform better than the individual members. Model averaging from these four methods were superior to the best of the individual members in 76% of the cases. Optimal combinations on all watersheds included at least one of each of the four hydrological models. None of the optimal combinations included all members of the ensemble of 12 hydrographs. The Granger-Ramanathan average variant C (GRC) is recommended as the best compromise between accuracy, speed of execution, and simplicity.

  6. Simulating lattice fermions by microcanonically averaging out the nonlocal dependence of the fermionic action

    International Nuclear Information System (INIS)

    Azcoiti, V.; Cruz, A.; Di Carlo, G.; Grillo, A.F.; Vladikas, A.

    1991-01-01

    We attempt to increase the efficiency of simulations of dynamical fermions on the lattice by calculating the fermionic determinant just once for all the values of the theory's gauge coupling and flavor number. Our proposal is based on the determination of an effective fermionic action by the calculation of the fermionic determinant averaged over configurations at fixed gauge energy. The feasibility of our method is justified by the observed volume dependence of the fluctuations of the logarithm of the determinant. The algorithm we have used in order to calculate the fermionic determinant, based on the determination of all the eigenvalues of the fermionic matrix at zero mass, also enables us to obtain results at any fermion mass, with a single fermionic simulation. We test the method by simulating compact lattice QED, finding good agreement with other standard calculations. New results on the phase transition of compact QED with massless fermions on 6 4 and 8 4 lattices are also presented

  7. Relationship Between Kinetics of Inflow and Outflow as the Basis of a Computer Simulation for Solving Compartmental Models: Example of Electrolyte Transfers in Cardiovascular Tissues

    Energy Technology Data Exchange (ETDEWEB)

    Llaurado, J. G. [Biomedical Engineering Group, Marquette University (United States); Marquette School of Medicine, Milwaukee (United States); Nuclear Medicine Service of Veterans Administration Center, Wood, WI (United States)

    1971-02-15

    A method commonly used for the study of the distribution of a substance among the different spaces ol a biological tissue is the continuous washout (outflow) and isotope counting of fragments of tissue previously incubated with a tracer. A first order kinetics compartmental system can be postulated and characterized by the transport rates (k) at which the substance of interest moves across its different compartments. Direct solution from the outflow data requires knowledge of the initial conditions for, or to have access for measurements in, each compartment. This cannot be fulfilled in most biological problems. In the course of studying {sup 22}Na distribution in segments of arteries a digital computer simulation approach was developed to solve the system. In the belief that the approach transcends this particular application, its mathematical basis is herein presented: the movement of radioactive tracer obeys Divides dq/d Divides = - Divides k Divides Divides q Divides + Divides r Divides (1) where |q| is a vector of response functions for each compartment, |k] is a square matrix of transport rate constants and |r| is a vector of input rates to the system. Solution of Eq. 1 is Divides q Divides = e{sup - Divides k Divides t} {integral}{sub 0}{sup t} e{sup Divides k Divides t} Divides r Divides dt + e{sup - Divides k Divides t} Divides q{sub 0} Divides (2) (i) For an inflow experiment, with 0 initial conditions and a constant unit input rate |r{sub u}| Divides q Divides = ( Divides I Divides - e{sup - Divides k Divides t}) Divides k Divides {sup -1} Divides r{sub u} Divides (3) as t --> {infinity}, Divides q{sub {infinity}} Divides = Divides k Divides {sup -1} Divides r{sub u} Divides , which replaced in Eq. 3, Divides q Divides = Divides q{sub {infinity}} Divides -e{sup - Divides k Divides t} Divides q{sub {infinity}} Divides (4) (ii) For an outflow experiment Divides r Divides = 0 and Eq. 2 becomes Divides q Divides = e{sup - Divides k Divides t} Divides q{sub 0

  8. Reynolds-Averaged Navier-Stokes Simulation of a 2D Circulation Control Wind Tunnel Experiment

    Science.gov (United States)

    Allan, Brian G.; Jones, Greg; Lin, John C.

    2011-01-01

    Numerical simulations are performed using a Reynolds-averaged Navier-Stokes (RANS) flow solver for a circulation control airfoil. 2D and 3D simulation results are compared to a circulation control wind tunnel test conducted at the NASA Langley Basic Aerodynamics Research Tunnel (BART). The RANS simulations are compared to a low blowing case with a jet momentum coefficient, C(sub u), of 0:047 and a higher blowing case of 0.115. Three dimensional simulations of the model and tunnel walls show wall effects on the lift and airfoil surface pressures. These wall effects include a 4% decrease of the midspan sectional lift for the C(sub u) 0.115 blowing condition. Simulations comparing the performance of the Spalart Allmaras (SA) and Shear Stress Transport (SST) turbulence models are also made, showing the SST model compares best to the experimental data. A Rotational/Curvature Correction (RCC) to the turbulence model is also evaluated demonstrating an improvement in the CFD predictions.

  9. Hybrid Large Eddy Simulation / Reynolds Averaged Navier-Stokes Modeling in Directed Energy Applications

    Science.gov (United States)

    Zilberter, Ilya Alexandrovich

    In this work, a hybrid Large Eddy Simulation / Reynolds-Averaged Navier Stokes (LES/RANS) turbulence model is applied to simulate two flows relevant to directed energy applications. The flow solver blends the Menter Baseline turbulence closure near solid boundaries with a Lenormand-type subgrid model in the free-stream with a blending function that employs the ratio of estimated inner and outer turbulent length scales. A Mach 2.2 mixing nozzle/diffuser system representative of a gas laser is simulated under a range of exit pressures to assess the ability of the model to predict the dynamics of the shock train. The simulation captures the location of the shock train responsible for pressure recovery but under-predicts the rate of pressure increase. Predicted turbulence production at the wall is found to be highly sensitive to the behavior of the RANS turbulence model. A Mach 2.3, high-Reynolds number, three-dimensional cavity flow is also simulated in order to compute the wavefront aberrations of an optical beam passing thorough the cavity. The cavity geometry is modeled using an immersed boundary method, and an auxiliary flat plate simulation is performed to replicate the effects of the wind-tunnel boundary layer on the computed optical path difference. Pressure spectra extracted on the cavity walls agree with empirical predictions based on Rossiter's formula. Proper orthogonal modes of the wavefront aberrations in a beam originating from the cavity center agree well with experimental data despite uncertainty about in flow turbulence levels and boundary layer thicknesses over the wind tunnel window. Dynamic mode decomposition of a planar wavefront spanning the cavity reveals that wavefront distortions are driven by shear layer oscillations at the Rossiter frequencies; these disturbances create eddy shocklets that propagate into the free-stream, creating additional optical wavefront distortion.

  10. Reynolds-averaged Navier-Stokes and Large-Eddy Simulation Over and Inside Inhomogeneous Forests

    DEFF Research Database (Denmark)

    Boudreault, Louis-Etienne

    the performance of wind models in such environment.A systematic method to acquire gridded input of canopy structure from aircraft based LiDAR scans of heterogeneous forests is defined. An extensive validation against ground-based measurements of the vertically summed frontal area density(or plant area index......) and tree height is performed. The method is optimized both in terms of plant area index magnitude and spatial variability. A forest grid is generated from the LiDAR method using airplane scans of a 5×5 km2 forested site in Sweden. The grid serves as the basis for Reynolds-averaged Navier-Stokes (RANS......) simulations. Wind observations from an instrumented mast are used for validation where a good correlation is found for the mean wind speed of two contrasting wind directions with different influences from the upstream forest. The effects of successive simplifications of the forest representation show...

  11. Cylinder-averaged histories of nitrogen oxide in a DI diesel with simulated turbocharging

    Science.gov (United States)

    Donahue, Ronald J.; Borman, Gary L.; Bower, Glenn R.

    1994-10-01

    An experimental study was conducted using the dumping technique (total cylinder sampling) to produce cylinder mass-averaged nitric oxide histories. Data were taken using a four stroke diesel research engine employing a quiescent chamber, high pressure direct injection fuel system, and simulated turbocharging. Two fuels were used to determine fuel cetane number effects. Two loads were run, one at an equivalence ratio of 0.5 and the other at a ratio of 0.3. The engine speed was held constant at 1500 rpm. Under the turbocharged and retarded timing conditions of this study, nitric oxide was produced up to the point of about 85% mass burned. Two different models were used to simulate the engine mn conditions: the phenomenological Hiroyasu spray-combustion model, and the three dimensional, U.W.-ERO modified KIVA-2 computational fluid dynamic code. Both of the models predicted the correct nitric oxide trend. Although the modified KIVA-2 combustion model using Zeldovich kinetics correctly predicted the shapes of the nitric oxide histories, it did not predict the exhaust concentrations without arbitrary adjustment based on experimental values.

  12. Large Eddy/Reynolds-Averaged Navier-Stokes Simulations of CUBRC Base Heating Experiments

    Science.gov (United States)

    Salazar, Giovanni; Edwards, Jack R.; Amar, Adam J.

    2012-01-01

    ven with great advances in computational techniques and computing power during recent decades, the modeling of unsteady separated flows, such as those encountered in the wake of a re-entry vehicle, continues to be one of the most challenging problems in CFD. Of most interest to the aerothermodynamics community is accurately predicting transient heating loads on the base of a blunt body, which would result in reduced uncertainties and safety margins when designing a re-entry vehicle. However, the prediction of heat transfer can vary widely depending on the turbulence model employed. Therefore, selecting a turbulence model which realistically captures as much of the flow physics as possible will result in improved results. Reynolds Averaged Navier Stokes (RANS) models have become increasingly popular due to their good performance with attached flows, and the relatively quick turnaround time to obtain results. However, RANS methods cannot accurately simulate unsteady separated wake flows, and running direct numerical simulation (DNS) on such complex flows is currently too computationally expensive. Large Eddy Simulation (LES) techniques allow for the computation of the large eddies, which contain most of the Reynolds stress, while modeling the smaller (subgrid) eddies. This results in models which are more computationally expensive than RANS methods, but not as prohibitive as DNS. By complimenting an LES approach with a RANS model, a hybrid LES/RANS method resolves the larger turbulent scales away from surfaces with LES, and switches to a RANS model inside boundary layers. As pointed out by Bertin et al., this type of hybrid approach has shown a lot of promise for predicting turbulent flows, but work is needed to verify that these models work well in hypersonic flows. The very limited amounts of flight and experimental data available presents an additional challenge for researchers. Recently, a joint study by NASA and CUBRC has focused on collecting heat transfer data

  13. Large eddy simulation in a rotary blood pump: Viscous shear stress computation and comparison with unsteady Reynolds-averaged Navier-Stokes simulation.

    Science.gov (United States)

    Torner, Benjamin; Konnigk, Lucas; Hallier, Sebastian; Kumar, Jitendra; Witte, Matthias; Wurm, Frank-Hendrik

    2018-06-01

    Numerical flow analysis (computational fluid dynamics) in combination with the prediction of blood damage is an important procedure to investigate the hemocompatibility of a blood pump, since blood trauma due to shear stresses remains a problem in these devices. Today, the numerical damage prediction is conducted using unsteady Reynolds-averaged Navier-Stokes simulations. Investigations with large eddy simulations are rarely being performed for blood pumps. Hence, the aim of the study is to examine the viscous shear stresses of a large eddy simulation in a blood pump and compare the results with an unsteady Reynolds-averaged Navier-Stokes simulation. The simulations were carried out at two operation points of a blood pump. The flow was simulated on a 100M element mesh for the large eddy simulation and a 20M element mesh for the unsteady Reynolds-averaged Navier-Stokes simulation. As a first step, the large eddy simulation was verified by analyzing internal dissipative losses within the pump. Then, the pump characteristics and mean and turbulent viscous shear stresses were compared between the two simulation methods. The verification showed that the large eddy simulation is able to reproduce the significant portion of dissipative losses, which is a global indication that the equivalent viscous shear stresses are adequately resolved. The comparison with the unsteady Reynolds-averaged Navier-Stokes simulation revealed that the hydraulic parameters were in agreement, but differences for the shear stresses were found. The results show the potential of the large eddy simulation as a high-quality comparative case to check the suitability of a chosen Reynolds-averaged Navier-Stokes setup and turbulence model. Furthermore, the results lead to suggest that large eddy simulations are superior to unsteady Reynolds-averaged Navier-Stokes simulations when instantaneous stresses are applied for the blood damage prediction.

  14. Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Co-Axial Supersonic Free-Jet Experiment

    Science.gov (United States)

    Baurle, R. A.; Edwards, J. R.

    2009-01-01

    Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The baseline value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was noted when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid simulation results showed the same trends as the baseline Reynolds-averaged predictions. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions are suggested as a remedy to this dilemma. Comparisons between resolved second-order turbulence statistics and their modeled Reynolds-averaged counterparts were also performed.

  15. Evidence for ultrafast outflows in radio-quiet AGNs - III. Location and energetics

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-05-01

    Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ˜0.0003-0.03 pc (˜ 102-104rs) from the central black hole, consistent with what is expected for accretion disc winds/outflows. The mass outflow rates are constrained between ˜0.01 and 1 M⊙ yr-1, corresponding to >rsim5-10 per cent of the accretion rates. The average lower/upper limits on the mechanical power are log? 42.6-44.6 erg s-1. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyfert galaxies.

  16. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs: III - Location and Energetics

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-01-01

    Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval approx.0.0003-0.03pc (approx.10(exp 2)-10(exp 4)tau(sub s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between approx.0.01- 1 Stellar Mass/y, corresponding to approx. or >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are logE(sub K) approx. or = 42.6-44.6 erg/s. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN r.osmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies .

  17. Low-Frequency Oscillations and Transport Processes Induced by Multiscale Transverse Structures in the Polar Wind Outflow: A Three-Dimensional Simulation

    Science.gov (United States)

    Ganguli, Supriya B.; Gavrishchaka, Valeriy V.

    1999-01-01

    Multiscale transverse structures in the magnetic-field-aligned flows have been frequently observed in the auroral region by FAST and Freja satellites. A number of multiscale processes, such as broadband low-frequency oscillations and various cross-field transport effects are well correlated with these structures. To study these effects, we have used our three-dimensional multifluid model with multiscale transverse inhomogeneities in the initial velocity profile. Self-consistent-frequency mode driven by local transverse gradients in the generation of the low field-aligned ion flow and associated transport processes were simulated. Effects of particle interaction with the self-consistent time-dependent three-dimensional wave potential have been modeled using a distribution of test particles. For typical polar wind conditions it has been found that even large-scale (approximately 50 - 100 km) transverse inhomogeneities in the flow can generate low-frequency oscillations that lead to significant flow modifications, cross-field particle diffusion, and other transport effects. It has also been shown that even small-amplitude (approximately 10 - 20%) short-scale (approximately 10 km) modulations of the original large-scale flow profile significantly increases low-frequency mode generation and associated cross-field transport, not only at the local spatial scales imposed by the modulations but also on global scales. Note that this wave-induced cross-field transport is not included in any of the global numerical models of the ionosphere, ionosphere-thermosphere, or ionosphere-polar wind. The simulation results indicate that the wave-induced cross-field transport not only affects the ion outflow rates but also leads to a significant broadening of particle phase-space distribution and transverse particle diffusion.

  18. An implementation of the maximum-caliber principle by replica-averaged time-resolved restrained simulations.

    Science.gov (United States)

    Capelli, Riccardo; Tiana, Guido; Camilloni, Carlo

    2018-05-14

    Inferential methods can be used to integrate experimental informations and molecular simulations. The maximum entropy principle provides a framework for using equilibrium experimental data, and it has been shown that replica-averaged simulations, restrained using a static potential, are a practical and powerful implementation of such a principle. Here we show that replica-averaged simulations restrained using a time-dependent potential are equivalent to the principle of maximum caliber, the dynamic version of the principle of maximum entropy, and thus may allow us to integrate time-resolved data in molecular dynamics simulations. We provide an analytical proof of the equivalence as well as a computational validation making use of simple models and synthetic data. Some limitations and possible solutions are also discussed.

  19. Bayesian model averaging using particle filtering and Gaussian mixture modeling : Theory, concepts, and simulation experiments

    NARCIS (Netherlands)

    Rings, J.; Vrugt, J.A.; Schoups, G.; Huisman, J.A.; Vereecken, H.

    2012-01-01

    Bayesian model averaging (BMA) is a standard method for combining predictive distributions from different models. In recent years, this method has enjoyed widespread application and use in many fields of study to improve the spread-skill relationship of forecast ensembles. The BMA predictive

  20. Model of averaged turbulent flow around cylindrical column for simulation of the saltation

    Czech Academy of Sciences Publication Activity Database

    Kharlamova, Irina; Kharlamov, Alexander; Vlasák, Pavel

    2014-01-01

    Roč. 21, č. 2 (2014), s. 103-110 ISSN 1802-1484 R&D Projects: GA ČR GA103/09/1718 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : sediment transport * flow around cylinder * logarithmic profile * dipole line * averaged turbulent flow Subject RIV: BK - Fluid Dynamics

  1. Implementation, Comparison and Application of an Average Simulation Model of a Wind Turbine Driven Doubly Fed Induction Generator

    Directory of Open Access Journals (Sweden)

    Lidula N. Widanagama Arachchige

    2017-10-01

    Full Text Available Wind turbine driven doubly-fed induction generators (DFIGs are widely used in the wind power industry. With the increasing penetration of wind farms, analysis of their effect on power systems has become a critical requirement. This paper presents the modeling of wind turbine driven DFIGs using the conventional vector controls in a detailed model of a DFIG that represents power electronics (PE converters with device level models and proposes an average model eliminating the PE converters. The PSCAD/EMTDC™ (4.6 electromagnetic transient simulation software is used to develop the detailed and the proposing average model of a DFIG. The comparison of the two models reveals that the designed average DFIG model is adequate for simulating and analyzing most of the transient conditions.

  2. Lattice Boltzmann simulations of the time-averaged forces on a cylinder in a sound field

    International Nuclear Information System (INIS)

    Haydock, David

    2005-01-01

    We show that lattice Boltzmann simulations can be used to model the radiation force on an object in a standing wave acoustic field and comparisons are made to theoretical predictions. We show how viscous effects change the radiation force and predict the motion of a particle placed near a boundary where viscous effects are important

  3. Lattice Boltzmann simulations of the time-averaged forces on a cylinder in a sound field

    Energy Technology Data Exchange (ETDEWEB)

    Haydock, David [Unilever R and D Colworth, Sharnbrook, Bedford MK44 1LQ (United Kingdom); Department of Physics, Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2005-04-15

    We show that lattice Boltzmann simulations can be used to model the radiation force on an object in a standing wave acoustic field and comparisons are made to theoretical predictions. We show how viscous effects change the radiation force and predict the motion of a particle placed near a boundary where viscous effects are important.

  4. F-16XL Hybrid Reynolds-Averaged Navier-Stokes/Large Eddy Simulation on Unstructured Grids

    Science.gov (United States)

    Park, Michael A.; Abdol-Hamid, Khaled S.; Elmiligui, Alaa

    2015-01-01

    This study continues the Cranked Arrow Wing Aerodynamics Program, International (CAWAPI) investigation with the FUN3D and USM3D flow solvers. CAWAPI was established to study the F-16XL, because it provides a unique opportunity to fuse fight test, wind tunnel test, and simulation to understand the aerodynamic features of swept wings. The high-lift performance of the cranked-arrow wing planform is critical for recent and past supersonic transport design concepts. Simulations of the low speed high angle of attack Flight Condition 25 are compared: Detached Eddy Simulation (DES), Modi ed Delayed Detached Eddy Simulation (MDDES), and the Spalart-Allmaras (SA) RANS model. Iso- surfaces of Q criterion show the development of coherent primary and secondary vortices on the upper surface of the wing that spiral, burst, and commingle. SA produces higher pressure peaks nearer to the leading-edge of the wing than flight test measurements. Mean DES and MDDES pressures better predict the flight test measurements, especially on the outer wing section. Vorticies and vortex-vortex interaction impact unsteady surface pressures. USM3D showed many sharp tones in volume points spectra near the wing apex with low broadband noise and FUN3D showed more broadband noise with weaker tones. Spectra of the volume points near the outer wing leading-edge was primarily broadband for both codes. Without unsteady flight measurements, the flight pressure environment can not be used to validate the simulations containing tonal or broadband spectra. Mean forces and moment are very similar between FUN3D models and between USM3D models. Spectra of the unsteady forces and moment are broadband with a few sharp peaks for USM3D.

  5. Studies of Quasar Outflows

    Science.gov (United States)

    Arav, Nahum

    2002-01-01

    The main aim of this research program is to determine the ionization equilibrium and abundances in quasar outflows. Especially in the broad absorption line QSO PG 0946+301. We find that the outflow's metalicity is consistent with being solar, while the abundance ratio of phosphorus to other metals is at least ten times solar. These findings are based on diagnostics that are not sensitive to saturation and partial covering effects in the BALs (Broad Adsorption Lines), which considerably weakened previous claims for enhanced metalicity. Ample evidence for these effects is seen in the spectrum.

  6. Ensemble averaged two-phase flow numerical simulation in vertical ducts for the void-studying behavior in BWRs

    International Nuclear Information System (INIS)

    Mohsen Sharifpur; Mahmoud Salehi; Ali Nouri Brojerdi; Ali Arefmanesh

    2003-01-01

    Investigation upon generation of vapor in the two-phase flow and predication of its behaviour is an important problem in nuclear industries. Here, the use of the ensemble averaging is to drive the governing equations for each phase in the bubbly two phase flow (two fluid model) and to simulate the water channel inside the four fuel rods along the vertical line. The governing equations will be simplified by having the experience on BWRs and data, which are obtained to find the distribution of void fraction, velocity and other parameters for each phase along the tube. Finally, we compare the results with the simulated results obtained from RELAP 5 Mode 2. The advantage of this work is to offer a new technique to solve the ensemble averaged two-phase flow by imposing the energy balance equation rather than to use the ordinary energy equations. (author)

  7. Retrospective cost adaptive Reynolds-averaged Navier-Stokes k-ω model for data-driven unsteady turbulent simulations

    Science.gov (United States)

    Li, Zhiyong; Hoagg, Jesse B.; Martin, Alexandre; Bailey, Sean C. C.

    2018-03-01

    This paper presents a data-driven computational model for simulating unsteady turbulent flows, where sparse measurement data is available. The model uses the retrospective cost adaptation (RCA) algorithm to automatically adjust the closure coefficients of the Reynolds-averaged Navier-Stokes (RANS) k- ω turbulence equations to improve agreement between the simulated flow and the measurements. The RCA-RANS k- ω model is verified for steady flow using a pipe-flow test case and for unsteady flow using a surface-mounted-cube test case. Measurements used for adaptation of the verification cases are obtained from baseline simulations with known closure coefficients. These verification test cases demonstrate that the RCA-RANS k- ω model can successfully adapt the closure coefficients to improve agreement between the simulated flow field and a set of sparse flow-field measurements. Furthermore, the RCA-RANS k- ω model improves agreement between the simulated flow and the baseline flow at locations at which measurements do not exist. The RCA-RANS k- ω model is also validated with experimental data from 2 test cases: steady pipe flow, and unsteady flow past a square cylinder. In both test cases, the adaptation improves agreement with experimental data in comparison to the results from a non-adaptive RANS k- ω model that uses the standard values of the k- ω closure coefficients. For the steady pipe flow, adaptation is driven by mean stream-wise velocity measurements at 24 locations along the pipe radius. The RCA-RANS k- ω model reduces the average velocity error at these locations by over 35%. For the unsteady flow over a square cylinder, adaptation is driven by time-varying surface pressure measurements at 2 locations on the square cylinder. The RCA-RANS k- ω model reduces the average surface-pressure error at these locations by 88.8%.

  8. Determination of averaged axisymmetric flow surfaces according to results obtained by numerical simulation of flow in turbomachinery

    Directory of Open Access Journals (Sweden)

    Bogdanović-Jovanović Jasmina B.

    2012-01-01

    Full Text Available In the increasing need for energy saving worldwide, the designing process of turbomachinery, as an essential part of thermal and hydroenergy systems, goes in the direction of enlarging efficiency. Therefore, the optimization of turbomachinery designing strongly affects the energy efficiency of the entire system. In the designing process of turbomachinery blade profiling, the model of axisymmetric fluid flows is commonly used in technical practice, even though this model suits only the profile cascades with infinite number of infinitely thin blades. The actual flow in turbomachinery profile cascades is not axisymmetric, and it can be fictively derived into the axisymmetric flow by averaging flow parameters in the blade passages according to the circular coordinate. Using numerical simulations of flow in turbomachinery runners, its operating parameters can be preliminarily determined. Furthermore, using the numerically obtained flow parameters in the blade passages, averaged axisymmetric flow surfaces in blade profile cascades can also be determined. The method of determination of averaged flow parameters and averaged meridian streamlines is presented in this paper, using the integral continuity equation for averaged flow parameters. With thus obtained results, every designer can be able to compare the obtained averaged flow surfaces with axisymmetric flow surfaces, as well as the specific work of elementary stages, which are used in the procedure of blade designing. Numerical simulations of flow in an exemplary axial flow pump, used as a part of the thermal power plant cooling system, were performed using Ansys CFX. [Projekat Ministarstva nauke Republike Srbije, br. TR33040: Revitalization of existing and designing new micro and mini hydropower plants (from 100 kW to 1000 kW in the territory of South and Southeast Serbia

  9. Large-eddy simulation/Reynolds-averaged Navier-Stokes hybrid schemes for high speed flows

    Science.gov (United States)

    Xiao, Xudong

    Three LES/RANS hybrid schemes have been proposed for the prediction of high speed separated flows. Each method couples the k-zeta (Enstrophy) BANS model with an LES subgrid scale one-equation model by using a blending function that is coordinate system independent. Two of these functions are based on turbulence dissipation length scale and grid size, while the third one has no explicit dependence on the grid. To implement the LES/RANS hybrid schemes, a new rescaling-reintroducing method is used to generate time-dependent turbulent inflow conditions. The hybrid schemes have been tested on a Mach 2.88 flow over 25 degree compression-expansion ramp and a Mach 2.79 flow over 20 degree compression ramp. A special computation procedure has been designed to prevent the separation zone from expanding upstream to the recycle-plane. The code is parallelized using Message Passing Interface (MPI) and is optimized for running on IBM-SP3 parallel machine. The scheme was validated first for a flat plate. It was shown that the blending function has to be monotonic to prevent the RANS region from appearing in the LES region. In the 25 deg ramp case, the hybrid schemes provided better agreement with experiment in the recovery region. Grid refinement studies demonstrated the importance of using a grid independent blend function and further improvement with experiment in the recovery region. In the 20 deg ramp case, with a relatively finer grid, the hybrid scheme characterized by grid independent blending function well predicted the flow field in both the separation region and the recovery region. Therefore, with "appropriately" fine grid, current hybrid schemes are promising for the simulation of shock wave/boundary layer interaction problems.

  10. Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Guobin; Wang, Tinggui; Yang, Chenwei, E-mail: gbmou@ustc.edu.cn [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026 (China)

    2017-07-20

    The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

  11. Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

    International Nuclear Information System (INIS)

    Mou, Guobin; Wang, Tinggui; Yang, Chenwei

    2017-01-01

    The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

  12. Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

    Science.gov (United States)

    Mou, Guobin; Wang, Tinggui; Yang, Chenwei

    2017-07-01

    The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

  13. PROTOSTELLAR OUTFLOW EVOLUTION IN TURBULENT ENVIRONMENTS

    International Nuclear Information System (INIS)

    Cunningham, Andrew J.; Frank, Adam; Carroll, Jonathan; Blackman, Eric G.; Quillen, Alice C.

    2009-01-01

    The link between turbulence in star-forming environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows, we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers'-type turbulence and produces a driving scale length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star-forming environments. In the last section, we contrast our work and its conclusions with previous studies which claim that jets cannot be the source of turbulence.

  14. Active galactic nucleus outflows in galaxy discs

    Science.gov (United States)

    Hartwig, Tilman; Volonteri, Marta; Dashyan, Gohar

    2018-05-01

    Galactic outflows, driven by active galactic nuclei (AGNs), play a crucial role in galaxy formation and in the self-regulated growth of supermassive black holes (BHs). AGN feedback couples to and affects gas, rather than stars, and in many, if not most, gas-rich galaxies cold gas is rotationally supported and settles in a disc. We present a 2D analytical model for AGN-driven outflows in a gaseous disc and demonstrate the main improvements, compared to existing 1D solutions. We find significant differences for the outflow dynamics and wind efficiency. The outflow is energy-driven due to inefficient cooling up to a certain AGN luminosity (˜1043 erg s-1 in our fiducial model), above which the outflow remains momentum-driven in the disc up to galactic scales. We reproduce results of 3D simulations that gas is preferentially ejected perpendicular to the disc and find that the fraction of ejected interstellar medium is lower than in 1D models. The recovery time of gas in the disc, defined as the free-fall time from the radius to which the AGN pushes the ISM at most, is remarkably short, of the order 1 Myr. This indicates that AGN-driven winds cannot suppress BH growth for long. Without the inclusion of supernova feedback, we find a scaling of the BH mass with the halo velocity dispersion of MBH ∝ σ4.8.

  15. Cellular automaton model in the fundamental diagram approach reproducing the synchronized outflow of wide moving jams

    International Nuclear Information System (INIS)

    Tian, Jun-fang; Yuan, Zhen-zhou; Jia, Bin; Fan, Hong-qiang; Wang, Tao

    2012-01-01

    Velocity effect and critical velocity are incorporated into the average space gap cellular automaton model [J.F. Tian, et al., Phys. A 391 (2012) 3129], which was able to reproduce many spatiotemporal dynamics reported by the three-phase theory except the synchronized outflow of wide moving jams. The physics of traffic breakdown has been explained. Various congested patterns induced by the on-ramp are reproduced. It is shown that the occurrence of synchronized outflow, free outflow of wide moving jams is closely related with drivers time delay in acceleration at the downstream jam front and the critical velocity, respectively. -- Highlights: ► Velocity effect is added into average space gap cellular automaton model. ► The physics of traffic breakdown has been explained. ► The probabilistic nature of traffic breakdown is simulated. ► Various congested patterns induced by the on-ramp are reproduced. ► The occurrence of synchronized outflow of jams depends on drivers time delay.

  16. Wind influence on a coastal buoyant outflow

    Science.gov (United States)

    Whitney, Michael M.; Garvine, Richard W.

    2005-03-01

    This paper investigates the interplay between river discharge and winds in forcing coastal buoyant outflows. During light winds a plume influenced by the Earth's rotation will flow down shelf (in the direction of Kelvin wave propagation) as a slender buoyancy-driven coastal current. Downwelling favorable winds augment this down-shelf flow, narrow the plume, and mix the water column. Upwelling favorable winds drive currents that counter the buoyancy-driven flow, spread plume waters offshore, and rapidly mix buoyant waters. Two criteria are developed to assess the wind influence on a buoyant outflow. The wind strength index (Ws) determines whether a plume's along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. Wind influence on across-shelf plume structure is rated with a timescale (ttilt) for the isopycnal tilting caused by wind-driven Ekman circulation. These criteria are used to characterize wind influence on the Delaware Coastal Current and can be applied to other coastal buoyant outflows. The Delaware buoyant outflow is simulated for springtime high-river discharge conditions. Simulation results and Ws values reveal that the coastal current is buoyancy-driven most of the time (∣Ws∣ Wind events, however, overwhelm the buoyancy-driven flow (∣Ws∣ > 1) several times during the high-discharge period. Strong upwelling events reverse the buoyant outflow; they constitute an important mechanism for transporting fresh water up shelf. Across-shelf plume structure is more sensitive to wind influence than the along-shelf flow. Values of ttilt indicate that moderate or strong winds persisting throughout a day can modify plume width significantly. Plume widening during upwelling events is accompanied by mixing that can erase the buoyant outflow.

  17. Relativistic Outflows from ADAFs

    Science.gov (United States)

    Becker, Peter; Subramanian, Prasad; Kazanas, Demosthenes

    2001-04-01

    Advection-dominated accretion flows (ADAFs) have a positive Bernoulli parameter, and are therefore gravitationally bound. The Newtonian ADAF model has been generalized recently to obtain the ADIOS model that includes outflows of energy and angular momentum, thereby allowing accretion to proceed self-consistently. However, the utilization of a Newtonian gravitational potential limits the ability of this model to describe the inner region of the disk, where any relativistic outflows are likely to originate. In this paper we modify the ADIOS scenario to incorporate a seudo - Newtonian potential, which approximates the effects of general relativity. The analysis yields a unique, self - similar solution for the structure of the coupled disk/wind system. Interesting features of the new solution include the relativistic character of the outflow in the vicinity of the radius of marginal stability, which represents the inner edge of the quasi-Keplerian disk in our model. Our self - similar model may therefore help to explain the origin of relativistic jets in active galaxies. At large distances the radial dependence of the accretion rate approachs the unique form dot M ∝ r^1/2, with an associated density variation given by ρ ∝ r-1. This density variation agrees with that implied by the dependence of the X-ray hard time lags on the Fourier frequency for a number of accreting galactic black hole candidates. While intriguing, the results of our self-similar model need to be confirmed in the future by incorporating a detailed physical description of the energization mechanism that drives the outflow, which is likely to be powered by the shear of the underlying accretion disk.

  18. An ensemble-based dynamic Bayesian averaging approach for discharge simulations using multiple global precipitation products and hydrological models

    Science.gov (United States)

    Qi, Wei; Liu, Junguo; Yang, Hong; Sweetapple, Chris

    2018-03-01

    Global precipitation products are very important datasets in flow simulations, especially in poorly gauged regions. Uncertainties resulting from precipitation products, hydrological models and their combinations vary with time and data magnitude, and undermine their application to flow simulations. However, previous studies have not quantified these uncertainties individually and explicitly. This study developed an ensemble-based dynamic Bayesian averaging approach (e-Bay) for deterministic discharge simulations using multiple global precipitation products and hydrological models. In this approach, the joint probability of precipitation products and hydrological models being correct is quantified based on uncertainties in maximum and mean estimation, posterior probability is quantified as functions of the magnitude and timing of discharges, and the law of total probability is implemented to calculate expected discharges. Six global fine-resolution precipitation products and two hydrological models of different complexities are included in an illustrative application. e-Bay can effectively quantify uncertainties and therefore generate better deterministic discharges than traditional approaches (weighted average methods with equal and varying weights and maximum likelihood approach). The mean Nash-Sutcliffe Efficiency values of e-Bay are up to 0.97 and 0.85 in training and validation periods respectively, which are at least 0.06 and 0.13 higher than traditional approaches. In addition, with increased training data, assessment criteria values of e-Bay show smaller fluctuations than traditional approaches and its performance becomes outstanding. The proposed e-Bay approach bridges the gap between global precipitation products and their pragmatic applications to discharge simulations, and is beneficial to water resources management in ungauged or poorly gauged regions across the world.

  19. Generation of shockwave and vortex structures at the outflow of a boiling water jet

    Science.gov (United States)

    Alekseev, M. V.; Lezhnin, S. I.; Pribaturin, N. A.; Sorokin, A. L.

    2014-12-01

    Results of numerical simulation for shock waves and generation of vortex structures during unsteady outflow of boiling liquid jet are presented. The features of evolution of shock waves and vortex structures formation during unsteady outflow of boiling water are compared with corresponding structures during unsteady gas outflow.

  20. Large-Eddy / Reynolds-Averaged Navier-Stokes Simulations of a Dual-Mode Scramjet Combustor

    Science.gov (United States)

    Fulton, Jesse A.; Edwards, Jack R.; Hassan, Hassan A.; Rockwell, Robert; Goyne, Christopher; McDaniel, James; Smith, Chad; Cutler, Andrew; Johansen, Craig; Danehy, Paul M.; hide

    2012-01-01

    Numerical simulations of reacting and non-reacting flows within a scramjet combustor configuration experimentally mapped at the University of Virginia s Scramjet Combustion Facility (operating with Configuration A ) are described in this paper. Reynolds-Averaged Navier-Stokes (RANS) and hybrid Large Eddy Simulation / Reynolds-Averaged Navier-Stokes (LES / RANS) methods are utilized, with the intent of comparing essentially blind predictions with results from non-intrusive flow-field measurement methods including coherent anti-Stokes Raman spectroscopy (CARS), hydroxyl radical planar laser-induced fluorescence (OH-PLIF), stereoscopic particle image velocimetry (SPIV), wavelength modulation spectroscopy (WMS), and focusing Schlieren. NC State's REACTMB solver was used both for RANS and LES / RANS, along with a 9-species, 19- reaction H2-air kinetics mechanism by Jachimowski. Inviscid fluxes were evaluated using Edwards LDFSS flux-splitting scheme, and the Menter BSL turbulence model was utilized in both full-domain RANS simulations and as the unsteady RANS portion of the LES / RANS closure. Simulations were executed and compared with experiment at two equivalence ratios, PHI = 0.17 and PHI = 0.34. Results show that the PHI = 0.17 flame is hotter near the injector while the PHI = 0.34 flame is displaced further downstream in the combustor, though it is still anchored to the injector. Reactant mixing was predicted to be much better at the lower equivalence ratio. The LES / RANS model appears to predict lower overall heat release compared to RANS (at least for PHI = 0.17), and its capability to capture the direct effects of larger turbulent eddies leads to much better predictions of reactant mixing and combustion in the flame stabilization region downstream of the fuel injector. Numerical results from the LES/RANS model also show very good agreement with OH-PLIF and SPIV measurements. An un-damped long-wave oscillation of the pre-combustion shock train, which caused

  1. Molecular outflows driven by low-mass protostars. I. Correcting for underestimates when measuring outflow masses and dynamical properties

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, Michael M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138 (United States); Arce, Héctor G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States); Mardones, Diego [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Lee, Jeong-Eun [Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of); Matthews, Brenda C. [National Research Council of Canada, Herzberg Astronomy and Astrophysics, 5071 W. Saanich Road, Victoria, BC V9E 2E7 (Canada); Stutz, Amelia M. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Williams, Jonathan P., E-mail: mdunham@cfa.harvard.edu [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

    2014-03-01

    We present a survey of 28 molecular outflows driven by low-mass protostars, all of which are sufficiently isolated spatially and/or kinematically to fully separate into individual outflows. Using a combination of new and archival data from several single-dish telescopes, 17 outflows are mapped in {sup 12}CO (2-1) and 17 are mapped in {sup 12}CO (3-2), with 6 mapped in both transitions. For each outflow, we calculate and tabulate the mass (M {sub flow}), momentum (P {sub flow}), kinetic energy (E {sub flow}), mechanical luminosity (L {sub flow}), and force (F {sub flow}) assuming optically thin emission in LTE at an excitation temperature, T {sub ex}, of 50 K. We show that all of the calculated properties are underestimated when calculated under these assumptions. Taken together, the effects of opacity, outflow emission at low velocities confused with ambient cloud emission, and emission below the sensitivities of the observations increase outflow masses and dynamical properties by an order of magnitude, on average, and factors of 50-90 in the most extreme cases. Different (and non-uniform) excitation temperatures, inclination effects, and dissociation of molecular gas will all work to further increase outflow properties. Molecular outflows are thus almost certainly more massive and energetic than commonly reported. Additionally, outflow properties are lower, on average, by almost an order of magnitude when calculated from the {sup 12}CO (3-2) maps compared to the {sup 12}CO (2-1) maps, even after accounting for different opacities, map sensitivities, and possible excitation temperature variations. It has recently been argued in the literature that the {sup 12}CO (3-2) line is subthermally excited in outflows, and our results support this finding.

  2. Predictive capability of average Stokes polarimetry for simulation of phase multilevel elements onto LCoS devices.

    Science.gov (United States)

    Martínez, Francisco J; Márquez, Andrés; Gallego, Sergi; Ortuño, Manuel; Francés, Jorge; Pascual, Inmaculada; Beléndez, Augusto

    2015-02-20

    Parallel-aligned (PA) liquid-crystal on silicon (LCoS) microdisplays are especially appealing in a wide range of spatial light modulation applications since they enable phase-only operation. Recently we proposed a novel polarimetric method, based on Stokes polarimetry, enabling the characterization of their linear retardance and the magnitude of their associated phase fluctuations or flicker, exhibited by many LCoS devices. In this work we apply the calibrated values obtained with this technique to show their capability to predict the performance of spatially varying phase multilevel elements displayed onto the PA-LCoS device. Specifically we address a series of multilevel phase blazed gratings. We analyze both their average diffraction efficiency ("static" analysis) and its associated time fluctuation ("dynamic" analysis). Two different electrical configuration files with different degrees of flicker are applied in order to evaluate the actual influence of flicker on the expected performance of the diffractive optical elements addressed. We obtain a good agreement between simulation and experiment, thus demonstrating the predictive capability of the calibration provided by the average Stokes polarimetric technique. Additionally, it is obtained that for electrical configurations with less than 30° amplitude for the flicker retardance, they may not influence the performance of the blazed gratings. In general, we demonstrate that the influence of flicker greatly diminishes when the number of quantization levels in the optical element increases.

  3. Flow and transport simulation of Madeira River using three depth-averaged two-equation turbulence closure models

    Directory of Open Access Journals (Sweden)

    Li-ren Yu

    2012-03-01

    Full Text Available This paper describes a numerical simulation in the Amazon water system, aiming to develop a quasi-three-dimensional numerical tool for refined modeling of turbulent flow and passive transport of mass in natural waters. Three depth-averaged two-equation turbulence closure models, k˜−ε˜,k˜−w˜, and k˜−ω˜ , were used to close the non-simplified quasi-three dimensional hydrodynamic fundamental governing equations. The discretized equations were solved with the advanced multi-grid iterative method using non-orthogonal body-fitted coarse and fine grids with collocated variable arrangement. Except for steady flow computation, the processes of contaminant inpouring and plume development at the beginning of discharge, caused by a side-discharge of a tributary, have also been numerically investigated. The three depth-averaged two-equation closure models are all suitable for modeling strong mixing turbulence. The newly established turbulence models such as the k˜−ω˜ model, with a higher order of magnitude of the turbulence parameter, provide a possibility for improving computational precision.

  4. An investigation of the effect of pore scale flow on average geochemical reaction rates using direct numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Molins, Sergi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Trebotich, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division; Steefel, Carl I. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Shen, Chaopeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division

    2012-03-30

    The scale-dependence of geochemical reaction rates hinders their use in continuum scale models intended for the interpretation and prediction of chemical fate and transport in subsurface environments such as those considered for geologic sequestration of CO2. Processes that take place at the pore scale, especially those involving mass transport limitations to reactive surfaces, may contribute to the discrepancy commonly observed between laboratory-determined and continuum-scale or field rates. In this study we investigate the dependence of mineral dissolution rates on the pore structure of the porous media by means of pore scale modeling of flow and multicomponent reactive transport. The pore scale model is composed of high-performance simulation tools and algorithms for incompressible flow and conservative transport combined with a general-purpose multicomponent geochemical reaction code. The model performs direct numerical simulation of reactive transport based on an operator-splitting approach to coupling transport and reactions. The approach is validated with a Poiseuille flow single-pore experiment and verified with an equivalent 1-D continuum-scale model of a capillary tube packed with calcite spheres. Using the case of calcite dissolution as an example, the high-resolution model is used to demonstrate that nonuniformity in the flow field at the pore scale has the effect of decreasing the overall reactivity of the system, even when systems with identical reactive surface area are considered. In conclusion, the effect becomes more pronounced as the heterogeneity of the reactive grain packing increases, particularly where the flow slows sufficiently such that the solution approaches equilibrium locally and the average rate becomes transport-limited.

  5. Formation and spatial distribution of hypervelocity stars in AGN outflows

    Science.gov (United States)

    Wang, Xiawei; Loeb, Abraham

    2018-05-01

    We study star formation within outflows driven by active galactic nuclei (AGN) as a new source of hypervelocity stars (HVSs). Recent observations revealed active star formation inside a galactic outflow at a rate of ∼ 15M⊙yr-1 . We verify that the shells swept up by an AGN outflow are capable of cooling and fragmentation into cold clumps embedded in a hot tenuous gas via thermal instabilities. We show that cold clumps of ∼ 103 M⊙ are formed within ∼ 105 yrs. As a result, stars are produced along outflow's path, endowed with the outflow speed at their formation site. These HVSs travel through the galactic halo and eventually escape into the intergalactic medium. The expected instantaneous rate of star formation inside the outflow is ∼ 4 - 5 orders of magnitude greater than the average rate associated with previously proposed mechanisms for producing HVSs, such as the Hills mechanism and three-body interaction between a star and a black hole binary. We predict the spatial distribution of HVSs formed in AGN outflows for future observational probe.

  6. State Averages

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of a variety of averages for each state or territory as well as the national average, including each quality measure, staffing, fine amount and number of...

  7. The Mass Outflow Rate of the Milky Way

    Science.gov (United States)

    Fox, Andrew

    2017-08-01

    The balance between gaseous inflow and outflow regulates star formation in spiral galaxies. This paradigm can be tested in the Milky Way, but whereas the star formation rate and inflow rate have both been measured, the outflow rate has not. We propose an archival COS program to determine the Galactic outflow rate in cool gas ( 10^4 K) by surveying UV absorption line high-velocity clouds (HVCs). This project will make use of the newly updated Hubble Spectroscopic Legacy Archive, which contains a uniformly reduced sample of 233 COS G130M spectra of background AGN. The outflow rate will be determined by (1) searching for redshifted HVCs; (2) modeling the clouds with photoionization simulations to determine their masses and physical properties; (3) combining the cloud masses with their velocities and distances. We will measure how the outflow is distributed spatially across the sky, calculate its mass loading factor, and compare the line profiles to synthetic spectra extracted from new hydrodynamic simulations. The distribution of HVC velocities will inform us what fraction of the outflowing clouds will escape the halo and what fraction will circulate back to the disk, to better understand how and where gas enters and exits the Milky Way.

  8. Molecular outflows in protostellar evolution

    International Nuclear Information System (INIS)

    Fukui, Y.; Iwata, T.; Mizuno, A.; Ogawa, H.; Kawabata, K.; Sugitani, K.

    1989-01-01

    Molecular outflow is an energetic mass-ejection phenomenon associated with very early stage of stellar evolution. The large kinetic energy involved in the phenomenon indicates that outflow may play an essential role in the process of star formation, particularly by extracting angular momentum. Most of the previous searches have been strongly biased toward optical or near-infrared signposts of star formation. They are not able, therefore, to provide the complete database necessary for a statistical study of the evolutionary status of molecular outflow. To overcome this difficulty, it is of vital importance to make an unbiased search of single molecular clouds for molecular outflows; here we report the final result of such a survey of the Lynds 1641 dark cloud. We show that molecular outflows are characterized by a total luminosity significantly greater than that of T Tauri stars. This indicates that molecular outflow corresponds to the main accretion phase of protostellar evolution, in which the luminosity excess is due to the gravitational energy released by dynamical mass accretion onto the protostellar core. (author)

  9. THE TURBULENT ORIGIN OF OUTFLOW AND SPIN MISALIGNMENT IN MULTIPLE STAR SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Offner, Stella S. R.; Lee, Katherine I.; Arce, Héctor G.; Fielding, Drummond B. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Dunham, Michael M., E-mail: soffner@astro.umass.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2016-08-10

    The protostellar outflows of wide-separation forming binaries frequently appear misaligned. We use magneto-hydrodynamic simulations to investigate the alignment of protostellar spin and molecular outflows for forming binary pairs. We show that the protostellar pairs, which form from turbulent fragmentation within a single parent core, have randomly oriented angular momentum. Although the pairs migrate to closer separations, their spins remain partially misaligned. We produce {sup 12}CO(2-1) synthetic observations of the simulations and characterize the outflow orientation in the emission maps. The CO-identified outflows exhibit a similar random distribution and are also statistically consistent with the observed distribution of molecular outflows. We conclude that the observed misalignment provides a clear signature of binary formation via turbulent fragmentation. The persistence of misaligned outflows and stellar spins following dynamical evolution may provide a signature of binary origins for more evolved multiple star systems.

  10. THE TURBULENT ORIGIN OF OUTFLOW AND SPIN MISALIGNMENT IN MULTIPLE STAR SYSTEMS

    International Nuclear Information System (INIS)

    Offner, Stella S. R.; Lee, Katherine I.; Arce, Héctor G.; Fielding, Drummond B.; Dunham, Michael M.

    2016-01-01

    The protostellar outflows of wide-separation forming binaries frequently appear misaligned. We use magneto-hydrodynamic simulations to investigate the alignment of protostellar spin and molecular outflows for forming binary pairs. We show that the protostellar pairs, which form from turbulent fragmentation within a single parent core, have randomly oriented angular momentum. Although the pairs migrate to closer separations, their spins remain partially misaligned. We produce 12 CO(2-1) synthetic observations of the simulations and characterize the outflow orientation in the emission maps. The CO-identified outflows exhibit a similar random distribution and are also statistically consistent with the observed distribution of molecular outflows. We conclude that the observed misalignment provides a clear signature of binary formation via turbulent fragmentation. The persistence of misaligned outflows and stellar spins following dynamical evolution may provide a signature of binary origins for more evolved multiple star systems.

  11. Modeling of extreme freshwater outflow from the north-eastern Japanese river basins to western Pacific Ocean

    Science.gov (United States)

    Troselj, Josko; Sayama, Takahiro; Varlamov, Sergey M.; Sasaki, Toshiharu; Racault, Marie-Fanny; Takara, Kaoru; Miyazawa, Yasumasa; Kuroki, Ryusuke; Yamagata, Toshio; Yamashiki, Yosuke

    2017-12-01

    This study demonstrates the importance of accurate extreme discharge input in hydrological and oceanographic combined modeling by introducing two extreme typhoon events. We investigated the effects of extreme freshwater outflow events from river mouths on sea surface salinity distribution (SSS) in the coastal zone of the north-eastern Japan. Previous studies have used observed discharge at the river mouth, as well as seasonally averaged inter-annual, annual, monthly or daily simulated data. Here, we reproduced the hourly peak discharge during two typhoon events for a targeted set of nine rivers and compared their impact on SSS in the coastal zone based on observed, climatological and simulated freshwater outflows in conjunction with verification of the results using satellite remote-sensing data. We created a set of hourly simulated freshwater outflow data from nine first-class Japanese river basins flowing to the western Pacific Ocean for the two targeted typhoon events (Chataan and Roke) and used it with the integrated hydrological (CDRMV3.1.1) and oceanographic (JCOPE-T) model, to compare the case using climatological mean monthly discharges as freshwater input from rivers with the case using our hydrological model simulated discharges. By using the CDRMV model optimized with the SCE-UA method, we successfully reproduced hindcasts for peak discharges of extreme typhoon events at the river mouths and could consider multiple river basin locations. Modeled SSS results were verified by comparison with Chlorophyll-a distribution, observed by satellite remote sensing. The projection of SSS in the coastal zone became more realistic than without including extreme freshwater outflow. These results suggest that our hydrological models with optimized model parameters calibrated to the Typhoon Roke and Chataan cases can be successfully used to predict runoff values from other extreme precipitation events with similar physical characteristics. Proper simulation of extreme

  12. Knowledge Outflows from Foreign Subsidiaries

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf

    This paper analyzes the MNC subsidiaries’ trade-off between the need for knowledge creation and the need for knowledge protection, and relates it to the extent of knowledge outflows generated within the host location. Combining research in International Business with Social Theory, we find...... the value of the subsidiary’s knowledge stock is very high, the need for knowledge protection restrains reciprocity mechanisms in knowledge exchanges, thus reducing the extent of knowledge outflows to the host location. This study contributes to the literature on the firm-level antecedents of FDI...... that subsidiaries that extensively draw on external knowledge sources are also more likely to generate knowledge outflows to local firms. We argue that this may be explained by the subsidiaries’ willingness to build the trust that facilitates the establishment of reciprocal knowledge linkages. However, when...

  13. Molecular Outflows: Explosive versus Protostellar

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis A.; Rodríguez, Luis F.; Palau, Aina; Loinard, Laurent [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico); Schmid-Burgk, Johannes [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany)

    2017-02-10

    With the recent recognition of a second, distinctive class of molecular outflows, namely the explosive ones not directly connected to the accretion–ejection process in star formation, a juxtaposition of the morphological and kinematic properties of both classes is warranted. By applying the same method used in Zapata et al., and using {sup 12}CO( J = 2-1) archival data from the Submillimeter Array, we contrast two well-known explosive objects, Orion KL and DR21, to HH 211 and DG Tau B, two flows representative of classical low-mass protostellar outflows. At the moment, there are only two well-established cases of explosive outflows, but with the full availability of ALMA we expect that more examples will be found in the near future. The main results are the largely different spatial distributions of the explosive flows, consisting of numerous narrow straight filament-like ejections with different orientations and in almost an isotropic configuration, the redshifted with respect to the blueshifted components of the flows (maximally separated in protostellar, largely overlapping in explosive outflows), the very-well-defined Hubble flow-like increase of velocity with distance from the origin in the explosive filaments versus the mostly non-organized CO velocity field in protostellar objects, and huge inequalities in mass, momentum, and energy of the two classes, at least for the case of low-mass flows. Finally, all the molecular filaments in the explosive outflows point back to approximately a central position (i.e., the place where its “exciting source” was located), contrary to the bulk of the molecular material within the protostellar outflows.

  14. Unsteady Reynolds Averaged Navier-Stokes and Large Eddy Simulations of Flows across Staggered Tube Bundle for a VHTR Lower Plenum Design

    International Nuclear Information System (INIS)

    Choi, Hyeon Kyeong; Park, Jong Woon

    2013-01-01

    In this work, behavior of unsteady and oscillating flow through a typical tube bundle array are analyzed by unsteady computations: 2D unsteady Reynolds averaged Navier-Stokes (URANS) and 3D Large Eddy Simulation (LES) and the results are compared with existing experimental data. In order to confirm appropriateness and limitations of CFD applications in the Korean VHTR design, two types of unsteady computations are performed such as 2D unsteady Reynolds averaged Navier-Stokes (URANS) and 3D Large Eddy Simulation (LES) for the existing tube bundle array. The velocity component profiles are compared with the experimental data and it is concluded that the URANS with the standard k-ω model is reasonably appropriate for cost-effective VHTR lower plenum analysis. Nevertheless, if more accurate results are needed, the LES-Smagorinsky computation is recommended considering limitations in the time averaged RANS in capturing small eddies

  15. Numerical simulation of flow induced by a pitched blade turbine. Comparison of the sliding mesh technique and an averaged source term method

    Energy Technology Data Exchange (ETDEWEB)

    Majander, E.O.J.; Manninen, M.T. [VTT Energy, Espoo (Finland)

    1996-12-31

    The flow induced by a pitched blade turbine was simulated using the sliding mesh technique. The detailed geometry of the turbine was modelled in a computational mesh rotating with the turbine and the geometry of the reactor including baffles was modelled in a stationary co-ordinate system. Effects of grid density were investigated. Turbulence was modelled by using the standard k-{epsilon} model. Results were compared to experimental observations. Velocity components were found to be in good agreement with the measured values throughout the tank. Averaged source terms were calculated from the sliding mesh simulations in order to investigate the reliability of the source term approach. The flow field in the tank was then simulated in a simple grid using these source terms. Agreement with the results of the sliding mesh simulations was good. Commercial CFD-code FLUENT was used in all simulations. (author)

  16. Numerical simulation of flow induced by a pitched blade turbine. Comparison of the sliding mesh technique and an averaged source term method

    Energy Technology Data Exchange (ETDEWEB)

    Majander, E O.J.; Manninen, M T [VTT Energy, Espoo (Finland)

    1997-12-31

    The flow induced by a pitched blade turbine was simulated using the sliding mesh technique. The detailed geometry of the turbine was modelled in a computational mesh rotating with the turbine and the geometry of the reactor including baffles was modelled in a stationary co-ordinate system. Effects of grid density were investigated. Turbulence was modelled by using the standard k-{epsilon} model. Results were compared to experimental observations. Velocity components were found to be in good agreement with the measured values throughout the tank. Averaged source terms were calculated from the sliding mesh simulations in order to investigate the reliability of the source term approach. The flow field in the tank was then simulated in a simple grid using these source terms. Agreement with the results of the sliding mesh simulations was good. Commercial CFD-code FLUENT was used in all simulations. (author)

  17. Cosmic ray driven outflows in an ultraluminous galaxy

    Science.gov (United States)

    Fujita, Akimi; Mac Low, Mordecai-Mark

    2018-06-01

    In models of galaxy formation, feedback driven both by supernova (SN) and active galactic nucleus is not efficient enough to quench star formation in massive galaxies. Models of smaller galaxies have suggested that cosmic rays (CRs) play a major role in expelling material from the star-forming regions by diffusing SN energy to the lower density outskirts. We therefore run gas dynamical simulations of galactic outflows from a galaxy contained in a halo with 5 × 1012 M⊙ that resembles a local ultraluminous galaxy, including both SN thermal energy and a treatment of CRs using the same diffusion approximation as Salem & Bryan. We find that CR pressure drives a low-density bubble beyond the edge of the shell swept up by thermal pressure, but the main bubble driven by SN thermal pressure overtakes it later, which creates a large-scale biconical outflow. CRs diffusing into the disc are unable to entrain its gas in the outflows, yielding a mass-loading rate of only ˜ 0.1 per cent with varied CR diffusion coefficients. We find no significant difference in mass-loading rates in SN-driven outflows with or without CR pressure. Our simulations strongly suggest that it is hard to drive a heavily mass-loaded outflow with CRs from a massive halo potential, although more distributed star formation could lead to a different result.

  18. Toward the Validation of Depth-Averaged Three Dimensional, Rans Steady-State Simulations of Fluvial Flows at Natural Scale

    Science.gov (United States)

    Mateo Villanueva, P. A.; Hradisky, M.

    2010-12-01

    Simulations of fluvial flows are strongly influenced by geometric complexity and overall uncertainty on measured flow variables, including those assumed to be well known boundary conditions. Often, 2D steady-state models are used for computational simulations of flows at the scale of natural rivers. Such models have been successfully incorporated in iRIC (formerly MD_SWMS), one of the widely used quasi-3D CFD solvers to perform studies of environmental flows. iRIC aids in estimating such quantities as surface roughness and shear stress, which, in turn, can be used to estimate sediment transport. However, the computational results are inherently limited in accuracy because of restricting the computations to 2D, or quasi-3D, space, which can affect the values of these predictions. In the present work we perform computer-based simulations of fluvial flows using OpenFOAM, a free, open source fully 3D CFD software package, and compare our results to predictions obtained from iRIC. First, we study the suitability of OpenFOAM as the main CFD solver to analyze fluvial flows and validate our results for two well documented rectangular channel configurations: the first case consists of a large aspect-ratio channel (ratio of depth over width 0.017, ratio of depth over length 0.0019) with a rectangular obstacle mounted at the bottom wall; the second case involves a large aspect-ratio channel (ratio of depth over width 0.1, ratio of depth over length 0.0025) with cubic obstacles mounted at the lower wall (one obstacle) and upper wall (two obstacles). Secondly, we apply our model to simulation or river at natural scale and compare our results to the output obtained from iRIC to quantify the differences in velocity profiles and other flow parameters when comparable solution techniques are used. Steady-state, RANS k-epsilon models are employed for all simulations.

  19. Pressure fluctuation prediction in pump mode using large eddy simulation and unsteady Reynolds-averaged Navier–Stokes in a pump–turbine

    Directory of Open Access Journals (Sweden)

    De-You Li

    2016-06-01

    Full Text Available For pump–turbines, most of the instabilities couple with high-level pressure fluctuations, which are harmful to pump–turbines, even the whole units. In order to understand the causes of pressure fluctuations and reduce their amplitudes, proper numerical methods should be chosen to obtain the accurate results. The method of large eddy simulation with wall-adapting local eddy-viscosity model was chosen to predict the pressure fluctuations in pump mode of a pump–turbine compared with the method of unsteady Reynolds-averaged Navier–Stokes with two-equation turbulence model shear stress transport k–ω. Partial load operating point (0.91QBEP under 15-mm guide vane opening was selected to make a comparison of performance and frequency characteristics between large eddy simulation and unsteady Reynolds-averaged Navier–Stokes based on the experimental validation. Good agreement indicates that the method of large eddy simulation could be applied in the simulation of pump–turbines. Then, a detailed comparison of variation for peak-to-peak value in the whole passage was presented. Both the methods show that the highest level pressure fluctuations occur in the vaneless space. In addition, the propagation of amplitudes of blade pass frequency, 2 times of blade pass frequency, and 3 times of blade pass frequency in the circumferential and flow directions was investigated. Although the difference exists between large eddy simulation and unsteady Reynolds-averaged Navier–Stokes, the trend of variation in different parts is almost the same. Based on the analysis, using the same mesh (8 million, large eddy simulation underestimates pressure characteristics and shows a better result compared with the experiments, while unsteady Reynolds-averaged Navier–Stokes overestimates them.

  20. Galactic Outflows, Star Formation Histories, and Timescales in Starburst Dwarf Galaxies from STARBIRDS

    Science.gov (United States)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Heilman, Taryn N.; Mitchell, Noah P.; Kelley, Tyler

    2018-03-01

    Winds are predicted to be ubiquitous in low-mass, actively star-forming galaxies. Observationally, winds have been detected in relatively few local dwarf galaxies, with even fewer constraints placed on their timescales. Here, we compare galactic outflows traced by diffuse, soft X-ray emission from Chandra Space Telescope archival observations to the star formation histories derived from Hubble Space Telescope imaging of the resolved stellar populations in six starburst dwarfs. We constrain the longevity of a wind to have an upper limit of 25 Myr based on galaxies whose starburst activity has already declined, although a larger sample is needed to confirm this result. We find an average 16% efficiency for converting the mechanical energy of stellar feedback to thermal, soft X-ray emission on the 25 Myr timescale, somewhat higher than simulations predict. The outflows have likely been sustained for timescales comparable to the duration of the starbursts (i.e., 100's Myr), after taking into account the time for the development and cessation of the wind. The wind timescales imply that material is driven to larger distances in the circumgalactic medium than estimated by assuming short, 5-10 Myr starburst durations, and that less material is recycled back to the host galaxy on short timescales. In the detected outflows, the expelled hot gas shows various morphologies which are not consistent with a simple biconical outflow structure. The sample and analysis are part of a larger program, the STARBurst IRregular Dwarf Survey (STARBIRDS), aimed at understanding the lifecycle and impact of starburst activity in low-mass systems.

  1. Comparison of arma (autoregressive moving average) with mtm (markov transition matrix): modeling simulation and prediction of wind data

    International Nuclear Information System (INIS)

    Jafri, Y.Z.; Kamal, L.

    2009-01-01

    A generalized theory of ARMA modeling, covering a wide range of researches. with model identification, order determination, estimation and diagnostic checking is presented. We evolved standardization of wind data to overcome non-stationarity. With our techniques on generating synthetic values of wind series using MTM, we modeled and simulated autocorrelated function (ACF). MTM is found relatively a better simulator as compared to ARMA. We used twenty year of wind data. MTM required fast computation and suitable algorithm for backward calculations to yield ACF values. We found ARMA (p, q) model suitableble for both large range (1-6 hours) and short range (1-2 hours). This indicates that forecast values can be considered for appropriate wind energy conversion system. (author)

  2. The effect of outflowing water coolant with supercritical parameters on a barrier

    Directory of Open Access Journals (Sweden)

    Alekseev Maksim

    2017-01-01

    Full Text Available The outflow of supercritical coolant with different initial parameters and its impact on the barrier have been numerically simulated. Spatial and axial distributions of pressure and steam quality are presented. The force acting on the barrier at different parameters of the outflow has been calculated.

  3. Modeling jet and outflow feedback during star cluster formation

    Energy Technology Data Exchange (ETDEWEB)

    Federrath, Christoph [Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, VIC 3800 (Australia); Schrön, Martin [Department of Computational Hydrosystems, Helmholtz Centre for Environmental Research-UFZ, Permoserstr. 15, D-04318 Leipzig (Germany); Banerjee, Robi [Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany); Klessen, Ralf S., E-mail: christoph.federrath@monash.edu [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany)

    2014-08-01

    Powerful jets and outflows are launched from the protostellar disks around newborn stars. These outflows carry enough mass and momentum to transform the structure of their parent molecular cloud and to potentially control star formation itself. Despite their importance, we have not been able to fully quantify the impact of jets and outflows during the formation of a star cluster. The main problem lies in limited computing power. We would have to resolve the magnetic jet-launching mechanism close to the protostar and at the same time follow the evolution of a parsec-size cloud for a million years. Current computer power and codes fall orders of magnitude short of achieving this. In order to overcome this problem, we implement a subgrid-scale (SGS) model for launching jets and outflows, which demonstrably converges and reproduces the mass, linear and angular momentum transfer, and the speed of real jets, with ∼1000 times lower resolution than would be required without the SGS model. We apply the new SGS model to turbulent, magnetized star cluster formation and show that jets and outflows (1) eject about one-fourth of their parent molecular clump in high-speed jets, quickly reaching distances of more than a parsec, (2) reduce the star formation rate by about a factor of two, and (3) lead to the formation of ∼1.5 times as many stars compared to the no-outflow case. Most importantly, we find that jets and outflows reduce the average star mass by a factor of ∼ three and may thus be essential for understanding the characteristic mass of the stellar initial mass function.

  4. OUTFLOW AND HOT DUST EMISSION IN HIGH-REDSHIFT QUASARS

    International Nuclear Information System (INIS)

    Wang, Huiyuan; Xing, Feijun; Wang, Tinggui; Zhou, Hongyan; Zhang, Kai; Zhang, Shaohua

    2013-01-01

    Correlations of hot dust emission with outflow properties are investigated, based on a large z ∼ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus

  5. PROTOSTELLAR OUTFLOWS IN L1340

    Energy Technology Data Exchange (ETDEWEB)

    Walawender, Josh [W. M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Wolf-Chase, Grace [Astronomy Department, Adler Planetarium, 1300 South Lake Shore Drive, Chicago, IL 60605 (United States); Smutko, Michael [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); OLinger-Luscusk, JoAnn [California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States); Moriarty-Schieven, Gerald, E-mail: jmwalawender@keck.hawaii.edu [National Research Council—Herzberg Astronomy and Astrophysics, 5017 West Saanich Road, Victoria, BC, V9E 2E7 (Canada)

    2016-12-01

    We have searched the L1340 A, B, and C clouds for shocks from protostellar outflows using the H{sub 2} 2.122 μ m near-infrared line as a shock tracer. Substantial outflow activity has been found in each of the three regions of the cloud (L1340 A, L1340 B, and L1340 C). We find 42 distinct shock complexes (16 in L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those shock complexes into 12 distinct outflows and identify candidate source stars for each. We examine the properties ( A {sub V}, T {sub bol}, and L {sub bol}) of the source protostars and compare them to the properties of the general population of Class 0/I and flat spectral energy distribution protostars and find that there is an indication, albeit at low statistical significance, that the outflow-driving protostars are drawn from a population with lower A {sub V}, higher L {sub bol}, and lower T {sub bol} than the general population of protostars.

  6. Demonstration of two-phase Direct Numerical Simulation (DNS) methods potentiality to give information to averaged models: application to bubbles column

    International Nuclear Information System (INIS)

    Magdeleine, S.

    2009-11-01

    This work is a part of a long term project that aims at using two-phase Direct Numerical Simulation (DNS) in order to give information to averaged models. For now, it is limited to isothermal bubbly flows with no phase change. It could be subdivided in two parts: Firstly, theoretical developments are made in order to build an equivalent of Large Eddy Simulation (LES) for two phase flows called Interfaces and Sub-grid Scales (ISS). After the implementation of the ISS model in our code called Trio U , a set of various cases is used to validate this model. Then, special test are made in order to optimize the model for our particular bubbly flows. Thus we showed the capacity of the ISS model to produce a cheap pertinent solution. Secondly, we use the ISS model to perform simulations of bubbly flows in column. Results of these simulations are averaged to obtain quantities that appear in mass, momentum and interfacial area density balances. Thus, we processed to an a priori test of a complete one dimensional averaged model.We showed that this model predicts well the simplest flows (laminar and monodisperse). Moreover, the hypothesis of one pressure, which is often made in averaged model like CATHARE, NEPTUNE and RELAP5, is satisfied in such flows. At the opposite, without a polydisperse model, the drag is over-predicted and the uncorrelated A i flux needs a closure law. Finally, we showed that in turbulent flows, fluctuations of velocity and pressure in the liquid phase are not represented by the tested averaged model. (author)

  7. Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kadoura, Ahmad; Sun, Shuyu, E-mail: shuyu.sun@kaust.edu.sa; Salama, Amgad

    2014-08-01

    Accurate determination of thermodynamic properties of petroleum reservoir fluids is of great interest to many applications, especially in petroleum engineering and chemical engineering. Molecular simulation has many appealing features, especially its requirement of fewer tuned parameters but yet better predicting capability; however it is well known that molecular simulation is very CPU expensive, as compared to equation of state approaches. We have recently introduced an efficient thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up the simulation more than a million times, making the regenerated molecular simulation almost as fast as equation of state approaches. In this paper, this technique is first briefly reviewed and then numerically investigated in its capability of predicting ensemble averages of primary quantities at different neighboring thermodynamic conditions to the original simulated MCMCs. Moreover, this extrapolation technique is extended to predict second derivative properties (e.g. heat capacity and fluid compressibility). The method works by reweighting and reconstructing generated MCMCs in canonical ensemble for Lennard-Jones particles. In this paper, system's potential energy, pressure, isochoric heat capacity and isothermal compressibility along isochors, isotherms and paths of changing temperature and density from the original simulated points were extrapolated. Finally, an optimized set of Lennard-Jones parameters (ε, σ) for single site models were proposed for methane, nitrogen and carbon monoxide.

  8. Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions

    KAUST Repository

    Kadoura, Ahmad Salim

    2014-08-01

    Accurate determination of thermodynamic properties of petroleum reservoir fluids is of great interest to many applications, especially in petroleum engineering and chemical engineering. Molecular simulation has many appealing features, especially its requirement of fewer tuned parameters but yet better predicting capability; however it is well known that molecular simulation is very CPU expensive, as compared to equation of state approaches. We have recently introduced an efficient thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up the simulation more than a million times, making the regenerated molecular simulation almost as fast as equation of state approaches. In this paper, this technique is first briefly reviewed and then numerically investigated in its capability of predicting ensemble averages of primary quantities at different neighboring thermodynamic conditions to the original simulated MCMCs. Moreover, this extrapolation technique is extended to predict second derivative properties (e.g. heat capacity and fluid compressibility). The method works by reweighting and reconstructing generated MCMCs in canonical ensemble for Lennard-Jones particles. In this paper, system\\'s potential energy, pressure, isochoric heat capacity and isothermal compressibility along isochors, isotherms and paths of changing temperature and density from the original simulated points were extrapolated. Finally, an optimized set of Lennard-Jones parameters (ε, σ) for single site models were proposed for methane, nitrogen and carbon monoxide. © 2014 Elsevier Inc.

  9. Plasma Outflows: Known Knowns, Known Unknowns, and The Unknown

    Science.gov (United States)

    Moore, T. E.

    2012-01-01

    A brief summary is given of i) what we know from observing ionospheric outflows and ii) how outflow parameterizations are being used in global simulations to evaluate their effects on magnetospheric dynamics. Then, a list of unanswered questions and issues to be resolved is given, followed by a description of the known future mission plans expressed in the Heliophysics Roadmap, such as Origin of Near-Earth Plasmas (ONEP), and Ion-Neutral Coupling in the Atmosphere (INCA). Finally, a set of requirements for definitive plasma outflow observations are identified, along with possible methods for fulfilling them in future missions. Since results of the current Heliophysics Decadal Survey are expected soon, it is hoped that future plans can be summarized and discussed without speculation at the GEM 2012 meeting.

  10. Massive Outflows Associated with ATLASGAL Clumps

    Science.gov (United States)

    Yang, A. Y.; Thompson, M. A.; Urquhart, J. S.; Tian, W. W.

    2018-03-01

    We have undertaken the largest survey for outflows within the Galactic plane using simultaneously observed {}13{CO} and {{{C}}}18{{O}} data. Out of a total of 919 ATLASGAL clumps, 325 have data suitable to identify outflows, and 225 (69% ± 3%) show high-velocity outflows. The clumps with detected outflows show significantly higher clump masses ({M}clump}), bolometric luminosities ({L}bol}), luminosity-to-mass ratios ({L}bol}/{M}clump}), and peak H2 column densities ({N}{{{H}}2}) compared to those without outflows. Outflow activity has been detected within the youngest quiescent clump (i.e., 70 μ {{m}} weak) in this sample, and we find that the outflow detection rate increases with {M}clump}, {L}bol}, {L}bol}/{M}clump}, and {N}{{{H}}2}, approaching 90% in some cases (UC H II regions = 93% ± 3%; masers = 86% ± 4%; HC H II regions = 100%). This high detection rate suggests that outflows are ubiquitous phenomena of massive star formation (MSF). The mean outflow mass entrainment rate implies a mean accretion rate of ∼ {10}-4 {M}ȯ {yr}}-1, in full agreement with the accretion rate predicted by theoretical models of MSF. Outflow properties are tightly correlated with {M}clump}, {L}bol}, and {L}bol}/{M}clump} and show the strongest relation with the bolometric clump luminosity. This suggests that outflows might be driven by the most massive and luminous source within the clump. The correlations are similar for both low-mass and high-mass outflows over 7 orders of magnitude, indicating that they may share a similar outflow mechanism. Outflow energy is comparable to the turbulent energy within the clump; however, we find no evidence that outflows increase the level of clump turbulence as the clumps evolve. This implies that the origin of turbulence within clumps is fixed before the onset of star formation.

  11. Two separate outflows in the dual supermassive black hole system NGC 6240.

    Science.gov (United States)

    Müller-Sánchez, F; Nevin, R; Comerford, J M; Davies, R I; Privon, G C; Treister, E

    2018-04-01

    Theoretical models and numerical simulations have established a framework of galaxy evolution in which galaxies merge and create dual supermassive black holes (with separations of one to ten kiloparsecs), which eventually sink into the centre of the merger remnant, emit gravitational waves and coalesce. The merger also triggers star formation and supermassive black hole growth, and gas outflows regulate the stellar content 1-3 . Although this theoretical picture is supported by recent observations of starburst-driven and supermassive black hole-driven outflows 4-6 , it remains unclear how these outflows interact with the interstellar medium. Furthermore, the relative contributions of star formation and black hole activity to galactic feedback remain unknown 7-9 . Here we report observations of dual outflows in the central region of the prototypical merger NGC 6240. We find a black-hole-driven outflow of [O III] to the northeast and a starburst-driven outflow of Hα to the northwest. The orientations and positions of the outflows allow us to isolate them spatially and study their properties independently. We estimate mass outflow rates of 10 and 75 solar masses per year for the Hα bubble and the [O III] cone, respectively. Their combined mass outflow is comparable to the star formation rate 10 , suggesting that negative feedback on star formation is occurring.

  12. Initial Beam Dynamics Simulations of a High-Average-Current Field-Emission Electron Source in a Superconducting RadioFrequency Gun

    Energy Technology Data Exchange (ETDEWEB)

    Mohsen, O. [Northern Illinois U.; Gonin, I. [Fermilab; Kephart, R. [Fermilab; Khabiboulline, T. [Fermilab; Piot, P. [Northern Illinois U.; Solyak, N. [Fermilab; Thangaraj, J. C. [Fermilab; Yakovlev, V. [Fermilab

    2018-01-05

    High-power electron beams are sought-after tools in support to a wide array of societal applications. This paper investigates the production of high-power electron beams by combining a high-current field-emission electron source to a superconducting radio-frequency (SRF) cavity. We especially carry out beam-dynamics simulations that demonstrate the viability of the scheme to form $\\sim$ 300 kW average-power electron beam using a 1+1/2-cell SRF gun.

  13. Superposed epoch analysis of O+ auroral outflow during sawtooth events and substorms

    Science.gov (United States)

    Nowrouzi, N.; Kistler, L. M.; Lund, E. J.; Cai, X.

    2017-12-01

    Sawtooth events are repeated injection of energetic particles at geosynchronous orbit. Studies have shown that 94% of sawtooth events occurred during magnetic storm times. The main factor that causes a sawtooth event is still an open question. Simulations have suggested that heavy ions like O+ may play a role in triggering the injections. One of the sources of the O+ in the Earth's magnetosphere is the nightside aurora. O+ ions coming from the nightside auroral region have direct access to the near-earth magnetotail. A model (Brambles et al. 2013) for interplanetary coronal mass ejection driven sawtooth events found that nightside O+ outflow caused the subsequent teeth of the sawtooth event through a feedback mechanism. This work is a superposed epoch analysis to test whether the observed auroral outflow supports this model. Using FAST spacecraft data from 1997-2007, we examine the auroral O+ outflow as a function of time relative to an injection onset. Then we determine whether the profile of outflow flux of O+ during sawtooth events is different from the outflow observed during isolated substorms. The auroral region boundaries are estimated using the method of (Andersson et al. 2004). Subsequently the O+ outflow flux inside these boundaries are calculated and binned as a function of superposed epoch time for substorms and sawtooth "teeth". In this way, we will determine if sawtooth events do in fact have greater O+ outflow, and if that outflow is predominantly from the nightside, as suggested by the model results.

  14. Geometry of anisotropic CO outflows

    International Nuclear Information System (INIS)

    Liseau, R.; Sandell, G.; Helsinki Univ., Observatory, Finland)

    1986-01-01

    A simple geometrical model for the space motions of the bipolar high-velocity CO outflows in regions of recent, active star formation is proposed. It is assumed that the velocity field of the neutral gas component can be represented by large-scale uniform motions. From observations of the spatial distribution and from the characteristics of the line shape of the high-velocity molecular gas emission the geometry of the line-emitting regions can be inferred, i.e., the direction in space and the collimating angle of the flow. The model has been applied to regions where a check on presently obtained results is provided by independent optical determinations of the motions of Herbig-Haro objects associated with the CO flows. These two methods are in good agreement and, furthermore, the results obtained provide convincingly strong evidence for the physical association of CO outflows and Herbig-Haro objects. This also supports the common view that a young stellar central source is responsible for the active phenomena observed in its environmental neighborhood. It is noteworthy that within the framework of the model the determination of the flow geometry of the high-velocity gas from CO measurements is independent of the distance to the source and, furthermore, can be done at relatively low spatial resolution. 32 references

  15. Atmospheric transport and outflow of polycyclic aromatic hydrocarbons from China

    Energy Technology Data Exchange (ETDEWEB)

    Chang Lang; Shu Tao; Wenxin Liu; Yanxu Zhang; Staci Simonich [Peking University, Beijing (China). Laboratory for Earth Surface Processes, College of Environmental Sciences

    2008-07-15

    A potential receptor influence function (PRIF) model, based on air mass forward trajectory calculations, was applied to simulate the atmospheric transport and outflow of polycyclic aromatic hydrocarbons (PAHs) emitted from China. With a 10 day atmospheric transport time, most neighboring countries and regions, as well as remote regions, were influenced by PAH emissions from China. Of the total annual PAH emission of 114 Gg, 92.7% remained within the boundary of mainland China. The geographic distribution of PRIFs within China was similar to the geographic distribution of the source regions, with high values in the North China Plain, Sichuan Basin, Shanxi, and Guizhou province. The Tarim basin and Sichuan basin had unfavorable meteorological conditions for PAH outflow. Of the PAH outflow from China (8092 tons or 7.1% of the total annual PAH emission), approximately 69.9% (5655 tons) reached no further than the offshore environment of mainland China and the South China Sea. Approximate 227, 71, 746, and 131 tons PAHs reached North Korea, South Korea, Russia-Mongolia region, and Japan, respectively, 2-4 days after the emission. Only 1.4 tons PAHs reached North America after more than 9 days. Interannual variation in the eastward PAH outflow was positively correlated to cold episodes of El Nino/Southern Oscillation. However, trans-Pacific atmospheric transport of PAHs from China was correlated to Pacific North America index (PNA) which is associated with the strength and position of westerly winds. 38 refs., 4 figs.

  16. The theoretical strength of rubber: numerical simulations of polyisoprene networks at high tensile strains evidence the role of average chain tortuosity

    International Nuclear Information System (INIS)

    Hanson, David E; Barber, John L

    2013-01-01

    The ultimate stress and strain of polyisoprene rubber were studied by numerical simulations of three-dimensional random networks, subjected to tensile strains high enough to cause chain rupture. Previously published molecular chain force extension models and a numerical network construction procedure were used to perform the simulations for network crosslink densities between 2 × 10 19 and 1 × 10 20 cm −3 , corresponding to experimental dicumyl-peroxide concentrations of 1–5 parts per hundred. At tensile failure (defined as the point of maximum stress), we find that the fraction of network chains ruptured is between 0.1% and 1%, depending on the crosslink density. The fraction of network chains that are taut, i.e. their end-to-end distance is greater than their unstretched contour length, ranges between 10% and 15% at failure. Our model predicts that the theoretical (defect-free) failure stress should be about twice the highest experimental value reported. For extensions approaching failure, tensile stress is dominated by the network morphology and purely enthalpic bond distortion forces and, in this regime, the model has essentially no free parameters. The average initial chain tortuosity (τ) appears to be an important statistical property of rubber networks; if the stress is scaled by τ and the tensile strain is scaled by τ −1 , we obtain a master curve for stress versus strain, valid for all crosslink densities. We derive an analytic expression for the average tortuosity, which is in agreement with values calculated in the simulations. (paper)

  17. The dependence of galactic outflows on the properties and orientation of zCOSMOS galaxies at z ∼ 1

    International Nuclear Information System (INIS)

    Bordoloi, R.; Lilly, S. J.; Hardmeier, E.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Fevre, O. Le; Garilli, B.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Zamorani, G.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Caputi, K.; Cucciati, O.; De la Torre, S.; De Ravel, L.; Iovino, A.

    2014-01-01

    We present an analysis of cool outflowing gas around galaxies, traced by Mg II absorption lines in the coadded spectra of a sample of 486 zCOSMOS galaxies at 1 ≤ z ≤ 1.5. These galaxies span a range of stellar masses (9.45 ≤ log 10 [M * /M ☉ ] ≤ 10.7) and star formation rates (0.14 ≤ log 10 [SFR/M ☉ yr –1 ] ≤ 2.35). We identify the cool outflowing component in the Mg II absorption and find that the equivalent width of the outflowing component increases with stellar mass. The outflow equivalent width also increases steadily with the increasing star formation rate of the galaxies. At similar stellar masses, the blue galaxies exhibit a significantly higher outflow equivalent width as compared to red galaxies. The outflow equivalent width shows strong correlation with the star formation surface density (Σ SFR ) of the sample. For the disk galaxies, the outflow equivalent width is higher for the face-on systems as compared to the edge-on ones, indicating that for the disk galaxies, the outflowing gas is primarily bipolar in geometry. Galaxies typically exhibit outflow velocities ranging from –150 km s –1 ∼–200 km s –1 and, on average, the face-on galaxies exhibit higher outflow velocity as compared to the edge-on ones. Galaxies with irregular morphologies exhibit outflow equivalent width as well as outflow velocities comparable to face on disk galaxies. These galaxies exhibit mass outflow rates >5-7 M ☉ yr –1 and a mass loading factor (η = M-dot out /SFR) comparable to the star formation rates of the galaxies.

  18. How Feasible is Adequate Yearly Progress (AYP? Simulations of School AYP "Uniform Averaging" and "Safe Harbor" under the No Child Left Behind Act

    Directory of Open Access Journals (Sweden)

    Jaekyung Lee

    2004-04-01

    Full Text Available The No Child Left Behind Act of 2001 (NCLB requires that schools make “adequate yearly progress” (AYP towards the goal of having 100 percent of their students become proficient by year 2013-14. Through simulation analyses of Maine and Kentucky school performance data collected during the 1990s, this study investigates how feasible schools would have met the AYP targets if the mandate had been applied in the past with “uniform averaging (rolling averages” and “safe harbor” options that have potential to help reduce the number of schools needing improvement or corrective action. Contrary to some expectations, the applications of both options would do little to reduce the risk of massive school failure due to unreasonably high AYP targets for all student groups. Implications of the results for the NCLB school accountability system and possible ways to make the current AYP more feasible and fair are discussed.

  19. Large Eddy Simulation and Reynolds-Averaged Navier-Stokes modeling of flow in a realistic pharyngeal airway model: an investigation of obstructive sleep apnea.

    Science.gov (United States)

    Mihaescu, Mihai; Murugappan, Shanmugam; Kalra, Maninder; Khosla, Sid; Gutmark, Ephraim

    2008-07-19

    Computational fluid dynamics techniques employing primarily steady Reynolds-Averaged Navier-Stokes (RANS) methodology have been recently used to characterize the transitional/turbulent flow field in human airways. The use of RANS implies that flow phenomena are averaged over time, the flow dynamics not being captured. Further, RANS uses two-equation turbulence models that are not adequate for predicting anisotropic flows, flows with high streamline curvature, or flows where separation occurs. A more accurate approach for such flow situations that occur in the human airway is Large Eddy Simulation (LES). The paper considers flow modeling in a pharyngeal airway model reconstructed from cross-sectional magnetic resonance scans of a patient with obstructive sleep apnea. The airway model is characterized by a maximum narrowing at the site of retropalatal pharynx. Two flow-modeling strategies are employed: steady RANS and the LES approach. In the RANS modeling framework both k-epsilon and k-omega turbulence models are used. The paper discusses the differences between the airflow characteristics obtained from the RANS and LES calculations. The largest discrepancies were found in the axial velocity distributions downstream of the minimum cross-sectional area. This region is characterized by flow separation and large radial velocity gradients across the developed shear layers. The largest difference in static pressure distributions on the airway walls was found between the LES and the k-epsilon data at the site of maximum narrowing in the retropalatal pharynx.

  20. Simulation of planar single-gate Si tunnel FET with average subthreshold swing of less than 60 mV/decade for 0.3 V operation

    Science.gov (United States)

    Kukita, Kentaro; Uechi, Tadayoshi; Shimokawa, Junji; Goto, Masakazu; Yokota, Yoshinori; Kawanaka, Shigeru; Tanamoto, Tetsufumi; Tanimoto, Hiroyoshi; Takagi, Shinichi

    2018-04-01

    Planar single-gate (SG) silicon (Si) tunnel field effect transistors (TFETs) are attracting interest for ultra-low voltage operation and CMOS applications. For the achievement of subthreshold swing (S.S.) less than thermal limit of Si MOSFETs (S.S. = 60 mV/decade at 300 K), previous studies have proposed the formation of a pocket region, which needs very difficult implantation process. In this work, a planar SG Si TFET without pocket was proposed by using the technology computer-aided design (TCAD) simulations. An average S.S. of less than 60 mV/decade for 0.3 V (= V gs = V ds) operation was obtained. It is found that both low average S.S. (= 27.8 mV/decade) and high on-current I on (= 3.8 µA/µm) are achieved without pocket doping by scaling the equivalent oxide thickness (EOT) and increasing the gate-to-source overlap length L ov.

  1. Outflow and Accretion Physics in Active Galactic Nuclei

    Science.gov (United States)

    McGraw, Sean Michael

    2016-09-01

    This dissertation focuses on placing observational constraints on outflows and accretion disks in active galactic nuclei (AGN) for the purpose of better understanding the physics of super-massive black holes (SMBHs) and their evolution with the host galaxy over cosmic time. Quasar outflows and their importance in SMBH-host galaxy co-evolution can be further understood by analyzing broad absorption lines (BALs) in rest-frame UV spectra that trace a range of wind conditions. We quantify the properties of the flows by conducting BAL variability studies using multiple-epoch spectra acquired primarily from MDM Observatory and from the Sloan Digital Sky Survey. Iron low-ionization BALs (FeLoBALs) are a rare type of outflow that may represent a transient phase in galaxy evolution, and we analyze the variations in 12 FeLoBAL quasars with redshifts between 0.7 ≤ z ≤ 1.9 and rest frame timescales between ˜10 d to 7.6 yr. We investigate BAL variability in 71 quasar outflows that exhibit P V absorption, a tracer of high column density gas (i.e. NH ≥ 1022 cm -2), in order to quantify the energies and momenta of the flows. We also characterize the variability patterns of 26 quasars with mini-BALs, an interesting class of absorbers that may represent a distinct phase in the evolution of outflows. Low-luminosity AGN (LLAGN) are important objects to study since their prominence in the local Universe suggest a possible evolution from the quasar era, and their low radiative outputs likely indicate a distinct mode of accretion onto the SMBH. We probe the accretion conditions in the LLAGN NGC 4203 by estimating the SMBH mass, which is obtained by modeling the 2-dimensional velocity field of the nebular gas using spectra from the Hubble Space Telescope. We detect significant BAL and mini-BAL variability in a subset of quasars from each of our samples, with measured rest-frame variability time-scales from days to years and over multiple years on average. Variable wavelength

  2. Design, experimental analysis, and unsteady Reynolds-averaged Navier-Stokes simulation of laboratory-scale counter-rotating vertical-axis turbines in marine environment

    Science.gov (United States)

    Doan, Minh; Padricelli, Claudrio; Obi, Shinnosuke; Totsuka, Yoshitaka

    2017-11-01

    We present the torque and power measurement of laboratory-scale counter-rotating vertical-axis hydrokinetic turbines, built around a magnetic hysteresis brake as the speed controller and a Hall-effect sensor as the rotational speed transducer. A couple of straight-three-bladed turbines were linked through a transmission of spur gears and timing pulleys and coupled to the electronic instrumentation via flexible shaft couplers. A total of 8 experiments in 2 configurations were conducted in the water channel facility (4-m long, 0.3-m wide, and 0.15-m deep). Power generation of the turbines (0.06-m rotor diameter) was measured and compared with that of single turbines of the same size. The wakes generated by these experiments were also measured by particle image velocimetry (PIV) and numerically simulated by unsteady Reynolds-averaged Navier-Stokes (URANS) simulation using OpenFOAM. Preliminary results from wake measurement indicated the mechanism of enhanced power production behind the counter-rotating configuration of vertical-axis turbines. Current address: Politecnico di Milano.

  3. Numerical Study of Natural Gas/Diesel Reactivity Controlled Compression Ignition Combustion with Large Eddy Simulation and Reynolds-Averaged Navier–Stokes Model

    Directory of Open Access Journals (Sweden)

    Amir-Hasan Kakaee

    2018-03-01

    Full Text Available In the current study, a comparative study is performed using Large Eddy Simulation (LES and Reynolds-averaged Navier–Stokes (RANS turbulence models on a natural gas/diesel Reactivity Controlled Compression Ignition (RCCI engine. The numerical results are validated against the available research work in the literature. The RNG (Re-Normalization Group k − ε and dynamic structure models are employed to model turbulent flow for RANS and LES simulations, respectively. Parameters like the premixed natural gas mass fraction, the second start of injection timing (SOI2 of diesel and the engine speed are studied to compare performance of RANS and LES models on combustion and pollutant emissions prediction. The results obtained showed that the LES and RANS model give almost similar predictions of cylinder pressure and heat release rate at lower natural gas mass fractions and late SOI2 timings. However, the LES showed improved capability to predict the natural gas auto-ignition and pollutant emissions prediction compared to RANS model especially at higher natural gas mass fractions.

  4. THE ROLE OF COSMIC-RAY PRESSURE IN ACCELERATING GALACTIC OUTFLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Christine M.; Pakmor, Rüdiger; Pfrommer, Christoph; Springel, Volker [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Marinacci, Federico [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Glover, Simon C. O. [Zentrum für Astronomie der Universität Heidelberg, ITA, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Clark, Paul C. [School of Physics and Astronomy, Queen’s Buildings, The Parade, Cardiff University, Cardiff CF24 3AA (United Kingdom); Smith, Rowan J., E-mail: Christine.Simpson@h-its.org [Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

    2016-08-20

    We study the formation of galactic outflows from supernova (SN) explosions with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SN placement and energy feedback, including cosmic rays (CRs), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.

  5. Quantifying and reducing model-form uncertainties in Reynolds-averaged Navier–Stokes simulations: A data-driven, physics-informed Bayesian approach

    International Nuclear Information System (INIS)

    Xiao, H.; Wu, J.-L.; Wang, J.-X.; Sun, R.; Roy, C.J.

    2016-01-01

    Despite their well-known limitations, Reynolds-Averaged Navier–Stokes (RANS) models are still the workhorse tools for turbulent flow simulations in today's engineering analysis, design and optimization. While the predictive capability of RANS models depends on many factors, for many practical flows the turbulence models are by far the largest source of uncertainty. As RANS models are used in the design and safety evaluation of many mission-critical systems such as airplanes and nuclear power plants, quantifying their model-form uncertainties has significant implications in enabling risk-informed decision-making. In this work we develop a data-driven, physics-informed Bayesian framework for quantifying model-form uncertainties in RANS simulations. Uncertainties are introduced directly to the Reynolds stresses and are represented with compact parameterization accounting for empirical prior knowledge and physical constraints (e.g., realizability, smoothness, and symmetry). An iterative ensemble Kalman method is used to assimilate the prior knowledge and observation data in a Bayesian framework, and to propagate them to posterior distributions of velocities and other Quantities of Interest (QoIs). We use two representative cases, the flow over periodic hills and the flow in a square duct, to evaluate the performance of the proposed framework. Both cases are challenging for standard RANS turbulence models. Simulation results suggest that, even with very sparse observations, the obtained posterior mean velocities and other QoIs have significantly better agreement with the benchmark data compared to the baseline results. At most locations the posterior distribution adequately captures the true model error within the developed model form uncertainty bounds. The framework is a major improvement over existing black-box, physics-neutral methods for model-form uncertainty quantification, where prior knowledge and details of the models are not exploited. This approach has

  6. Quantifying and reducing model-form uncertainties in Reynolds-averaged Navier–Stokes simulations: A data-driven, physics-informed Bayesian approach

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, H., E-mail: hengxiao@vt.edu; Wu, J.-L.; Wang, J.-X.; Sun, R.; Roy, C.J.

    2016-11-01

    Despite their well-known limitations, Reynolds-Averaged Navier–Stokes (RANS) models are still the workhorse tools for turbulent flow simulations in today's engineering analysis, design and optimization. While the predictive capability of RANS models depends on many factors, for many practical flows the turbulence models are by far the largest source of uncertainty. As RANS models are used in the design and safety evaluation of many mission-critical systems such as airplanes and nuclear power plants, quantifying their model-form uncertainties has significant implications in enabling risk-informed decision-making. In this work we develop a data-driven, physics-informed Bayesian framework for quantifying model-form uncertainties in RANS simulations. Uncertainties are introduced directly to the Reynolds stresses and are represented with compact parameterization accounting for empirical prior knowledge and physical constraints (e.g., realizability, smoothness, and symmetry). An iterative ensemble Kalman method is used to assimilate the prior knowledge and observation data in a Bayesian framework, and to propagate them to posterior distributions of velocities and other Quantities of Interest (QoIs). We use two representative cases, the flow over periodic hills and the flow in a square duct, to evaluate the performance of the proposed framework. Both cases are challenging for standard RANS turbulence models. Simulation results suggest that, even with very sparse observations, the obtained posterior mean velocities and other QoIs have significantly better agreement with the benchmark data compared to the baseline results. At most locations the posterior distribution adequately captures the true model error within the developed model form uncertainty bounds. The framework is a major improvement over existing black-box, physics-neutral methods for model-form uncertainty quantification, where prior knowledge and details of the models are not exploited. This approach

  7. Numerical simulation of the transient cavitating turbulent flows around the Clark-Y hydrofoil using modified partially averaged Navier-Stokes method

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Renfang; Luo, Xianwu [Tsinghua University, Beijing (China); Ji, Bin [Wuhan University, Hubei (China)

    2017-06-15

    This paper presents the implementation and assessment of a modified Partially averaged Navier-Stokes (PANS) turbulence model which can successfully predict the transient cavitating turbulent flows. The proposed model treats the standard k-e model as the parent model, and its main distinctive features are to (1) formulate the unresolved-to-total kinetic energy ratio (f{sub k}) based on the local grid size as well as turbulence length scale, and (2) vary the f{sub k}-field both in space and time. Numerical simulation used the modified PANS model for the sheet/cloud cavitating flows around a three-dimensional Clark-Y hydrofoil. The available experimental data and calculations of the standard k-e model, the f{sub k} = 0.8 PANS model, the f{sub k} = 0.5 PANS model are also provided for comparisons. The results show that the modified PANS model accurately captures the transient cavitation features as observed in experiments, namely, the attached sheet cavity grows in the flow direction until to a maximum length and then it breaks into a highly turbulent cloud cavity with three-dimensional structures in nature. Time-averaged drag/lift coefficients together with the streamwise velocity profiles predicted by the proposed model are in good agreement with the experimental data, and improvements are shown when compared with results of the standard k-e model, the f{sub k} = 0.8 PANS model and the f{sub k} = 0.5 PANS model. Overall, the modified PANS model shows its encouraging capability of predicting the transient cavitating turbulent flows.

  8. The Role of Ionospheric Outflow Preconditioning in Determining Storm Geoeffectiveness

    Science.gov (United States)

    Welling, D. T.; Liemohn, M. W.; Ridley, A. J.

    2012-12-01

    It is now well accepted that ionospheric outflow plays an important role in the development of the plasma sheet and ring current during geomagnetic storms. Furthermore, even during quiet times, ionospheric plasma populates the magnetospheric lobes, producing a reservoir of hydrogen and oxygen ions. When the Interplanetary Magnetic Field (IMF) turns southward, this reservoir is connected to the plasma sheet and ring current through magnetospheric convection. Hence, the conditions of the ionosphere and magnetospheric lobes leading up to magnetospheric storm onset have important implications for storm development. Despite this, there has been little research on this preconditioning; most global simulations begin just before storm onset, neglecting preconditioning altogether. This work explores the role of preconditioning in determining the geoeffectiveness of storms using a coupled global model system. A model of ionospheric outflow (the Polar Wind Outflow Model, PWOM) is two-way coupled to a global magnetohydrodynamic model (the Block-Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), which in turn drives a ring current model (the Ring current Atmosphere interactions Model, RAM). This unique setup is used to simulate an idealized storm. The model is started at many different times, from 1 hour before storm onset to 12 hours before. The effects of storm preconditioning are examined by investigating the total ionospheric plasma content in the lobes just before onset, the total ionospheric contribution in the ring current just after onset, and the effects on Dst, magnetic elevation angle at geosynchronous, and total ring current energy density. This experiment is repeated for different solar activity levels as set by F10.7 flux. Finally, a synthetic double-dip storm is constructed to see how two closely spaced storms affect each other by changing the preconditioning environment. It is found that preconditioning of the magnetospheric lobes via ionospheric

  9. Unsteady Reynolds-averaged Navier-Stokes simulations of inlet distortion in the fan system of a gas-turbine aero-engine

    Science.gov (United States)

    Spotts, Nathan

    As modern trends in commercial aircraft design move toward high-bypass-ratio fan systems of increasing diameter with shorter, nonaxisymmetric nacelle geometries, inlet distortion is becoming common in all operating regimes. The distortion may induce aerodynamic instabilities within the fan system, leading to catastrophic damage to fan blades, should the surge margin be exceeded. Even in the absence of system instability, the heterogeneity of the flow affects aerodynamic performance significantly. Therefore, an understanding of fan-distortion interaction is critical to aircraft engine system design. This thesis research elucidates the complex fluid dynamics and fan-distortion interaction by means of computational fluid dynamics (CFD) modeling of a complete engine fan system; including rotor, stator, spinner, nacelle and nozzle; under conditions typical of those encountered by commercial aircraft. The CFD simulations, based on a Reynolds-averaged Navier-Stokes (RANS) approach, were unsteady, three-dimensional, and of a full-annulus geometry. A thorough, systematic validation has been performed for configurations from a single passage of a rotor to a full-annulus system by comparing the predicted flow characteristics and aerodynamic performance to those found in literature. The original contributions of this research include the integration of a complete engine fan system, based on the NASA rotor 67 transonic stage and representative of the propulsion systems in commercial aircraft, and a benchmark case for unsteady RANS simulations of distorted flow in such a geometry under realistic operating conditions. This study is unique in that the complex flow dynamics, resulting from fan-distortion interaction, were illustrated in a practical geometry under realistic operating conditions. For example, the compressive stage is shown to influence upstream static pressure distributions and thus suppress separation of flow on the nacelle. Knowledge of such flow physics is

  10. Comparison of population-averaged and cluster-specific models for the analysis of cluster randomized trials with missing binary outcomes: a simulation study

    Directory of Open Access Journals (Sweden)

    Ma Jinhui

    2013-01-01

    Full Text Available Abstracts Background The objective of this simulation study is to compare the accuracy and efficiency of population-averaged (i.e. generalized estimating equations (GEE and cluster-specific (i.e. random-effects logistic regression (RELR models for analyzing data from cluster randomized trials (CRTs with missing binary responses. Methods In this simulation study, clustered responses were generated from a beta-binomial distribution. The number of clusters per trial arm, the number of subjects per cluster, intra-cluster correlation coefficient, and the percentage of missing data were allowed to vary. Under the assumption of covariate dependent missingness, missing outcomes were handled by complete case analysis, standard multiple imputation (MI and within-cluster MI strategies. Data were analyzed using GEE and RELR. Performance of the methods was assessed using standardized bias, empirical standard error, root mean squared error (RMSE, and coverage probability. Results GEE performs well on all four measures — provided the downward bias of the standard error (when the number of clusters per arm is small is adjusted appropriately — under the following scenarios: complete case analysis for CRTs with a small amount of missing data; standard MI for CRTs with variance inflation factor (VIF 50. RELR performs well only when a small amount of data was missing, and complete case analysis was applied. Conclusion GEE performs well as long as appropriate missing data strategies are adopted based on the design of CRTs and the percentage of missing data. In contrast, RELR does not perform well when either standard or within-cluster MI strategy is applied prior to the analysis.

  11. Large-Scale Outflows in Seyfert Galaxies

    Science.gov (United States)

    Colbert, E. J. M.; Baum, S. A.

    1995-12-01

    \\catcode`\\@=11 \\ialign{m @th#1hfil ##hfil \\crcr#2\\crcr\\sim\\crcr}}} \\catcode`\\@=12 Highly collimated outflows extend out to Mpc scales in many radio-loud active galaxies. In Seyfert galaxies, which are radio-quiet, the outflows extend out to kpc scales and do not appear to be as highly collimated. In order to study the nature of large-scale (>~1 kpc) outflows in Seyferts, we have conducted optical, radio and X-ray surveys of a distance-limited sample of 22 edge-on Seyfert galaxies. Results of the optical emission-line imaging and spectroscopic survey imply that large-scale outflows are present in >~{{1} /{4}} of all Seyferts. The radio (VLA) and X-ray (ROSAT) surveys show that large-scale radio and X-ray emission is present at about the same frequency. Kinetic luminosities of the outflows in Seyferts are comparable to those in starburst-driven superwinds. Large-scale radio sources in Seyferts appear diffuse, but do not resemble radio halos found in some edge-on starburst galaxies (e.g. M82). We discuss the feasibility of the outflows being powered by the active nucleus (e.g. a jet) or a circumnuclear starburst.

  12. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.; Korneev, Svyatoslav

    2014-01-01

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations

  13. Dissecting the Butterfly: Dual Outflows in the Dual AGN NGC 6240

    Science.gov (United States)

    Mueller Sanchez, Francisco; Comerford, Julie; Nevin, Rebecca; Davies, Richard; Treister, Ezequiel; Privon, George

    2018-01-01

    Current theories of galaxy evolution invoke some kind of feedback (from the stars or the supermassive black hole) to explain the properties of galaxies. However, numerical simulations and observations have not been able to evaluate the real impact of feedback in galaxies. This is largely because most studies have focused on studying stellar feedback or AGN feedback alone, instead of considering the combined effect of both. In fact, this is an unexplored territory for observations due to the difficulty of separating the contribution from the two sources.In this contribution I present the discovery of a dual outflow of different species of gas in the prototypical merging galaxy NGC 6240 using HST imaging, long-slit and integral-eld spectroscopy: an AGN-driven outflow of highly-ionized gas to the northeast and a starburst-driven outflow of ionized hydrogen to the northwest. The AGN outflow extends up to 4 kpc along a position angle of 56 degrees, has a conical shape with an opening angle of 52 degrees and a maximum line-of-sight velocity of 350 km/s. The WFC3 images also reveal a bubble of Halpha emission in the northwest, which has no counterpart in [O III], consistent with a scenario in which the starburst is ionizing and driving outflowing winds which inflate the bubble at an expansion velocity of 380 km/s. Assuming a spherical geometry for the starburst-driven bubble and a conical geometry for the AGN-driven outflow, we estimate mass outflow rates of 26 Msun/yr and 62 Msun/yr, respectively. We conclude that the AGN contribution to the evolution of the merger remnant and the formation of outflowing winds is signicant in the central 5 kpc of NGC 6240.

  14. Cerebral venous outflow and cerebrospinal fluid dynamics

    Directory of Open Access Journals (Sweden)

    Clive B. Beggs

    2014-12-01

    Full Text Available In this review, the impact of restricted cerebral venous outflow on the biomechanics of the intracranial fluid system is investigated. The cerebral venous drainage system is often viewed simply as a series of collecting vessels channeling blood back to the heart. However there is growing evidence that it plays an important role in regulating the intracranial fluid system. In particular, there appears to be a link between increased cerebrospinal fluid (CSF pulsatility in the Aqueduct of Sylvius and constricted venous outflow. Constricted venous outflow also appears to inhibit absorption of CSF into the superior sagittal sinus. The compliance of the cortical bridging veins appears to be critical to the behaviour of the intracranial fluid system, with abnormalities at this location implicated in normal pressure hydrocephalus. The compliance associated with these vessels appears to be functional in nature and dependent on the free egress of blood out of the cranium via the extracranial venous drainage pathways. Because constricted venous outflow appears to be linked with increased aqueductal CSF pulsatility, it suggests that inhibited venous blood outflow may be altering the compliance of the cortical bridging veins.

  15. OH outflows in star-forming regions

    International Nuclear Information System (INIS)

    Mirabel, I.F.; Ruiz, A.; Rodriguez, L.F.; Canto, J.; Universidad de Puer; Universidad de Puerto Rico, Rio Piedras; Universidad Nacional Autonoma de Mexico, Mexico City)

    1987-01-01

    The results from a survey for high-velocity OH in molecular outflows in star-forming regions are reported. High-velocity OH was detected in absorption in nine of these regions. When the telescope beam can resolve the outflows, they show similar anisotropic angular distribution as the redshifted and blueshifted CO. The OH transitions are markedly subthermal since for several sources it is found that the radiation that is being absorbed is a background continuum constituted by the cosmic component plus a small Galactic contribution. The absorbing OH appears to trace gas with higher velocities and lower densities than does the CO and, in some cases, provides information on the structure of the outflows at larger distances from the central source. At scales of 0.1 pc, the outflows are elongated in the direction of the steepest density gradient of the ambient cloud, suggesting that the large-scale collimation of the outflow is produced by the density structure of the ambient cloud. 29 references

  16. Zooplankton in the Arctic outflow

    Science.gov (United States)

    Soloviev, K. A.; Dritz, A. V.; Nikishina, A. B.

    2009-04-01

    Climate changes in the Arctic cause the changes in the current system that may have cascading effect on the structure of plankton community and consequently on the interlinked and delicately balanced food web. Zooplankton species are by definition incapable to perform horizontal moving. Their transport is connected with flowing water. There are zooplankton species specific for the definite water masses and they can be used as markers for the different currents. That allows us to consider zooplankton community composition as a result of water mixing in the studied area. Little is known however about the mechanisms by which spatial and temporal variability in advection affect dynamics of local populations. Ice conditions are also very important in the function of pelagic communities. Melting time is the trigger to all "plankton blooming" processes, and the duration of ice-free conditions determines the food web development in the future. Fram Strait is one of the key regions for the Arctic: the cold water outflow comes through it with the East Greenland Current and meets warm Atlantic water, the West Spitsbergen Current, producing complicated hydrological situation. During 2007 and 2008 we investigated the structure functional characteristics of zooplankton community in the Fram Strait region onboard KV "Svalbard" (April 2007, April and May 2008) and RV "Jan Mayen" (May 2007, August 2008). This study was conducted in frame of iAOOS Norway project "Closing the loop", which, in turn, was a part of IPY. During this cruises multidisciplinary investigations were performed, including sea-ice observations, CTD and ADCP profiling, carbon flux, nutrients and primary production measurements, phytoplankton sampling. Zooplankton was collected with the Hydro-Bios WP2 net and MultiNet Zooplankton Sampler, (mouth area 0.25 m2, mesh size 180 um).Samples were taken from the depth strata of 2000-1500, 1500-1000, 1000-500,500-200, 200-100, 100-60, 60-30, 30-0 m. Gut fluorescence

  17. Fading AGN Candidates: AGN Histories and Outflow Signatures

    Energy Technology Data Exchange (ETDEWEB)

    Keel, William C.; Maksym, W. Peter [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Lintott, Chris J. [Astrophysics, Oxford University and Adler Planetarium, 1300 S. Lakeshore Drive, Chicago, IL 60605 (United States); Bennert, Vardha N.; Scott, Bryan; Showley, Charles; Flatland, Kelsi [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Chojnowski, S. Drew [Department of Astronomy, New Mexico State University, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Moiseev, Alexei; Smirnova, Aleksandrina [Special Astrophysical Observatory, Russian Academy of Sciences, Nizhny Arkhyz, 369167 (Russian Federation); Schawinski, Kevin; Sartori, Lia F. [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Straße 27, CH-8093 Zurich (Switzerland); Urry, C. Megan [Department of Physics, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Pancoast, Anna [Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Schirmer, Mischa, E-mail: wkeel@ua.edu [Gemini Observatory, La Serena (Chile)

    2017-02-01

    We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q {sub ion} derived from photoionization balance in the brightest pixels in H α at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q {sub ion} values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2×10{sup 4} yr before the direct view of the nucleus. The e -folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and

  18. Fading AGN Candidates: AGN Histories and Outflow Signatures

    International Nuclear Information System (INIS)

    Keel, William C.; Maksym, W. Peter; Lintott, Chris J.; Bennert, Vardha N.; Scott, Bryan; Showley, Charles; Flatland, Kelsi; Chojnowski, S. Drew; Moiseev, Alexei; Smirnova, Aleksandrina; Schawinski, Kevin; Sartori, Lia F.; Urry, C. Megan; Pancoast, Anna; Schirmer, Mischa

    2017-01-01

    We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q ion derived from photoionization balance in the brightest pixels in H α at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q ion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2×10 4 yr before the direct view of the nucleus. The e -folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission

  19. Considering heterogeneities by transmissibilities averaging on adapted meshes in reservoir simulation; Prise en compte des heterogeneites par prise de moyenne des transmissivites sur maillages adaptes en simulation de reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Urgelli, D

    1998-10-16

    Reservoir heterogeneity can be described using geostatistical models. But these models generate the heterogeneity on millions of fine grid blocks, which leads to prohibitive computational costs for reservoir simulations. In order to reduce the number of grid blocks, averaging techniques are needed to up-scale the fine scale permeabilities to the larger scales appropriate for flow simulation and engineering calculations. Grid block permeability up-scaling for numerical reservoir simulations has been discussed for a long time in the literature. It is now recognized that a full permeability tensor is needed to get an accurate reservoir description. But, the equivalent permeability on coarse grid blocks cannot be used directly on the numerical scheme. Usually, the harmonic average of the coarse grid block permeability is used for the transmissibility calculation, but it might cause a loss of accuracy. The purpose of this thesis is to present a new procedure for computing the equivalent transmissibility in the discretized flow equations on Cartesian grids and Corner Point Geometry grids. An application of this technique to a finite volume type numerical scheme is detailed. The principle of this technique is to calculate a permeability term on a shifted block placed between the two adjacent blocks where the transmissibility must be determined. At the field scale, the flow region can be divided into two types : a linear flow pattern with a low pressure gradient far from the wells and a radial flow pattern with a high pressure gradient in the vicinity of the wells. The radial flow region is usually more important for the prediction of production forecast, because it is directly related to the well. This was demonstrated theoretically and numerically for 2-D problem. The transmissibility up-scaling in radial flow pattern consists to determine the transmissibilities in the vicinity of wells and the numerical Productivity Index simultaneously. This new method called `shifted

  20. Evolution of the outflow activity of protostars

    International Nuclear Information System (INIS)

    Bontemps, Sylvain

    1996-01-01

    After a first part describing the formation of low-mass stars (sites of stellar formation, protostellar evolution) and matter outflows from young objects (molecular flows and their origin, optical and radio jets, outflow mechanisms), this research thesis discusses the evolution of molecular flows by reprinting a published article (Evolution of outflow activity around low-mass embedded young stellar objects), and by outlining some remaining issues (differences between clouds of stellar formation, morphological evolution of molecular flows). The author then discusses the continuous radio centimetre emission: origin, systematic search for Class 0 objects by using the VLA (Very Large Array radio interferometer), presentation of a new Class 0 protostar (HH24MMS). The author reports the study of H_2 emission in the infrared: generalities on protostellar shocks, infrared jet by HH24MMS, H_2 emission at 10 microns by using the ISOCAM camera [fr

  1. The Upshear Environment-Outflow Interface of a Sheared, Rapidly Intensifying Tropical Cyclone

    Science.gov (United States)

    Ryglicki, D.; Doyle, J. D.; Jin, Y.; Hodyss, D.; Viner, K.

    2017-12-01

    An idealized, simulated tropical cyclone (TC) which undergoes rapid intensification in moderate vertical wind shear is shown to exhibit structural similarities to observed TCs of this class. Due to a complex vortex tilt evolution, enhanced convection causes enhanced outflow from the TC which subsequently serves to block and to divert environmental flow around the TC. This allows for the TC to come back into vertical alignment and undergo rapid intensification. A trajectory analysis indicates that blocking is limited to a narrow range of heights, indicating that the vertical profile of environmental winds is a key factor for permitting this evolution. Satellite observations indicate the presence of upper-level arcs extending upshear beyond the TC. Synthetic satellite imagery of the simulated TC indicates this is the termination of the outflow. Using a Helmholtz decomposition, it is found that the divergent component of the outflow extends 1000 km upshear into the environment, potentially explaining the 1000-km clearing seen in satellite observations.

  2. Data-Model and Inter-Model Comparisons of the GEM Outflow Events Using the Space Weather Modeling Framework

    Science.gov (United States)

    Welling, D. T.; Eccles, J. V.; Barakat, A. R.; Kistler, L. M.; Haaland, S.; Schunk, R. W.; Chappell, C. R.

    2015-12-01

    Two storm periods were selected by the Geospace Environment Modeling Ionospheric Outflow focus group for community collaborative study because of its high magnetospheric activity and extensive data coverage: the September 27 - October 4, 2002 corotating interaction region event and the October 22 - 29 coronal mass ejection event. During both events, the FAST, Polar, Cluster, and other missions made key observations, creating prime periods for data-model comparison. The GEM community has come together to simulate this period using many different methods in order to evaluate models, compare results, and expand our knowledge of ionospheric outflow and its effects on global dynamics. This paper presents Space Weather Modeling Framework (SWMF) simulations of these important periods compared against observations from the Polar TIDE, Cluster CODIF and EFW instruments. Emphasis will be given to the second event. Density and velocity of oxygen and hydrogen throughout the lobes, plasma sheet, and inner magnetosphere will be the focus of these comparisons. For these simulations, the SWMF couples the multifluid version of BATS-R-US MHD to a variety of ionospheric outflow models of varying complexity. The simplest is outflow arising from constant MHD inner boundary conditions. Two first-principles-based models are also leveraged: the Polar Wind Outflow Model (PWOM), a fluid treatment of outflow dynamics, and the Generalized Polar Wind (GPW) model, which combines fluid and particle-in-cell approaches. Each model is capable of capturing a different set of energization mechanisms, yielding different outflow results. The data-model comparisons will illustrate how well each approach captures reality and which energization mechanisms are most important. Inter-model comparisons will illustrate how the different outflow specifications affect the magnetosphere. Specifically, it is found that the GPW provides increased heavy ion outflow over a broader spatial range than the alternative

  3. Explosive Outflows from Forming Massive Stars

    OpenAIRE

    Bally, J.; Ginsburg, A.; Kasliwal, M. M.

    2016-01-01

    AO imaging of the near IR [Fe ii] and H_2 lines and ALMA CO J = 2 − 1 data confirms the explosive nature of the BN/KL outflow in Orion. N-body interactions in compact groups may be responsible for the production of powerful, explosive protostellar outflows and luminous infrared flares. The Orion event may have been triggered by a protostellar merger. First results of a search for Orion-like events in 200 nearby galaxies with the SPitzer InfraRed Intensive Transients Survey (SPIRITS) are brief...

  4. Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions

    KAUST Repository

    Kadoura, Ahmad Salim; Sun, Shuyu; Salama, Amgad

    2014-01-01

    thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up

  5. Detonation in supersonic radial outflow

    KAUST Repository

    Kasimov, Aslan R.

    2014-11-07

    We report on the structure and dynamics of gaseous detonation stabilized in a supersonic flow emanating radially from a central source. The steady-state solutions are computed and their range of existence is investigated. Two-dimensional simulations are carried out in order to explore the stability of the steady-state solutions. It is found that both collapsing and expanding two-dimensional cellular detonations exist. The latter can be stabilized by putting several rigid obstacles in the flow downstream of the steady-state sonic locus. The problem of initiation of standing detonation stabilized in the radial flow is also investigated numerically. © 2014 Cambridge University Press.

  6. Alignment between Protostellar Outflows and Filamentary Structure

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Ian W.; Dunham, Michael M.; Myers, Philip C.; Pokhrel, Riwaj; Sadavoy, Sarah I.; Lee, Katherine I.; Goodman, Alyssa A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States); Vorobyov, Eduard I. [Institute of Fluid Mechanics and Heat Transfer, TU Wien, Vienna, A-1060 (Austria); Tobin, John J. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Pineda, Jaime E. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Offner, Stella S. R. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Kristensen, Lars E. [Centre for Star and Planet Formation, Niels Bohr Institute and Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K (Denmark); Jørgensen, Jes K. [Niels Bohr Institute and Center for Star and Planet Formation, Copenhagen University, DK-1350 Copenhagen K. (Denmark); Bourke, Tyler L. [SKA Organization, Jodrell Bank Observatory, Lower Withington, Macclesfield, Cheshire SK11 9DL (United Kingdom); Arce, Héctor G. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Plunkett, Adele L., E-mail: ian.stephens@cfa.harvard.edu [European Southern Observatory, Av. Alonso de Cordova 3107, Vitacura, Santiago de Chile (Chile)

    2017-09-01

    We present new Submillimeter Array (SMA) observations of CO(2–1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus protostars, we characterize the orientation of the outflow angles and compare them with the orientation of the local filaments as derived from Herschel observations. We find that the relative angles between outflows and filaments are inconsistent with purely parallel or purely perpendicular distributions. Instead, the observed distribution of outflow-filament angles are more consistent with either randomly aligned angles or a mix of projected parallel and perpendicular angles. A mix of parallel and perpendicular angles requires perpendicular alignment to be more common by a factor of ∼3. Our results show that the observed distributions probably hold regardless of the protostar’s multiplicity, age, or the host core’s opacity. These observations indicate that the angular momentum axis of a protostar may be independent of the large-scale structure. We discuss the significance of independent protostellar rotation axes in the general picture of filament-based star formation.

  7. On the outflow of dense water from the Weddell and Ross Seas in OCCAM model

    Directory of Open Access Journals (Sweden)

    R. Kerr

    2012-06-01

    Full Text Available We describe the seasonal and interannual variability of volume transports in the Weddell and Ross Seas using the 1/12° 20-yr simulation of the OCCAM global ocean general circulation model. The average simulated full-depth cumulative volume transports were 28.5 ± 2.9 Sv (1 Sv ≡ 106 m3 s−1 and 13.4 ± 5.2 Sv, across the main export regions of the Weddell and Ross Seas, respectively. The values of mean outflow of Antarctic Bottom Water (AABW (defined by neutral density γn ≥ 28.27 kg m−3 from the Weddell and Ross Seas of 10.6 ± 3.1 Sv and 0.5 ± 0.7 Sv, respectively, agree with the range reported in historical observational studies. The export of Weddell Sea dense water in OCCAM is primarily determined by the strength of the Weddell Gyre. Variability in AABW export is predominantly at periods of ~1 yr and 2–4 yr.

  8. The Resolved Outflow from 3C 48

    Science.gov (United States)

    Shih, Hsin-Yi; Stockton, Alan

    2014-10-01

    We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the

  9. Delayed or No Feedback? Gas Outflows in Type 2 AGNs. III

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Jong-Hak; Son, Donghoon; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr, E-mail: hjbae@galaxy.yonsei.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2017-04-20

    We present gas kinematics based on the [O iii] λ 5007 line and their connection to galaxy gravitational potential, active galactic nucleus (AGN) energetics, and star formation, using a large sample of ∼110,000 AGNs and star-forming (SF) galaxies at z < 0.3. Gas and stellar velocity dispersions are comparable to each other in SF galaxies, indicating that the ionized gas kinematics can be accounted by the gravitational potential of host galaxies. In contrast, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. The [O iii] velocity–velocity dispersion (VVD) diagram dramatically expands toward high values as a function of AGN luminosity, implying that the outflows are AGN-driven, while SF galaxies do not show such a trend. We find that the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [O iii] profile. AGNs with strong outflow signatures show on average similar specific star formation rates (sSFRs) to those of star-forming galaxies. In contrast, AGNs with weak or no outflows have an order of magnitude lower sSFRs, suggesting that AGNs with current strong outflows do now show any negative AGN feedback and that it may take dynamical time to impact on star formation over galactic scales.

  10. Human cerebral venous outflow pathway depends on posture and central venous pressure

    DEFF Research Database (Denmark)

    Gisolf, J; van Lieshout, J J; van Heusden, K

    2004-01-01

    Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture...... and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R(2) = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway...

  11. A New Look at Speeding Outflows

    Science.gov (United States)

    Kohler, Susanna

    2018-02-01

    The compact centers of active galaxies known as active galactic nuclei, or AGN are known for the dynamic behavior they exhibit as the supermassive black holes at their centers accrete matter. New observations of outflows from a nearby AGN provide a more detailed look at what happens in these extreme environments.Outflows from GiantsThe powerful radio jets of Cygnus A, which extend far beyond the galaxy. [NRAO/AUI]AGN consist of a supermassive black hole of millions to tens of billions of solar masses surrounded by an accretion disk of in-falling matter. But not all the material falling toward the black hole accretes! Some of it is flung from the AGN via various types of outflows.The most well-known of these outflows are powerful radio jets collimated and incredibly fast-moving streams of particles that blast their way out of the host galaxy and into space. Only around 10% of AGN are observed to host such jets, however and theres another outflow thats more ubiquitous.Fast-Moving AbsorbersPerhaps 30% of AGN both those with and without observed radio jets host wider-angle, highly ionized gaseous outflows known as ultra-fast outflows (UFOs). Ultraviolet and X-ray radiation emitted from the AGN is absorbed by the UFO, revealing the outflows presence: absorption lines appear in the ultraviolet and X-ray spectra of the AGN, blue-shifted due to the high speeds of the absorbing gas in the outflow.Quasar PG 1211+143, indicated by the crosshairs at the center of the image, in the color context of its surroundings. [SDSS/S. Karge]But what is the nature of UFOs? Are they disk winds? Or are they somehow related to the radio jets? And what impact do they have on the AGNs host galaxy?X-ray and Ultraviolet CooperationNew observations are now providing fresh information about one particular UFO. A team of scientists led by Ashkbiz Danehkar (Harvard-Smithsonian Center for Astrophysics) recently used the Chandra and Hubble space telescopes to make the first simultaneous observations

  12. GAS OUTFLOWS IN SEYFERT GALAXIES: EFFECTS OF STAR FORMATION VERSUS AGN FEEDBACK

    Energy Technology Data Exchange (ETDEWEB)

    Melioli, C.; Pino, E. M. de Gouveia Dal, E-mail: claudio.melioli@iag.usp.br, E-mail: dalpino@iag.usp.br [Department of Astronomy (IAG-USP), University of Sao Paulo (Brazil)

    2015-10-20

    Large-scale, weakly collimated outflows are very common in galaxies with large infrared luminosities. In complex systems in particular, where intense star formation (SF) coexists with an active galactic nucleus (AGN), it is not clear yet from observations whether the SF, the AGN, or both are driving these outflows. Accreting supermassive black holes are expected to influence their host galaxies through kinetic and radiative feedback processes, but in a Seyfert galaxy, where the energy emitted in the nuclear region is comparable to that of the body of the galaxy, it is possible that stellar activity is also playing a key role in these processes. In order to achieve a better understanding of the mechanisms driving the gas evolution especially at the nuclear regions of these galaxies, we have performed high-resolution three-dimensional hydrodynamical simulations with radiative cooling considering the feedback from both SF regions, including supernova (Type I and II) explosions and an AGN jet emerging from the central region of the active spiral galaxy. We computed the gas mass lost by the system, separating the role of each of these injection energy sources on the galaxy evolution, and found that at scales within 1 kpc an outflow can be generally established considering intense nuclear SF only. The jet alone is unable to drive a massive gas outflow, although it can sporadically drag and accelerate clumps of the underlying outflow to very high velocities.

  13. Extreme Gaseous Outflows in Radio-Loud Narrow-Line Seyfert 1 Galaxies

    Science.gov (United States)

    Komossa, S.; Xu, D. W.; Wagner, A. Y.

    2018-04-01

    We present four radio-loud NLS1 galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km/s, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km/s. An ionization stratification (higher line shift at higher ionization potential) implies that we see a large-scale outflow rather than single, localized jet-cloud interactions. Similarly, the paucity of zero-velocity [OIII]λ5007 emitting gas implies the absence of a second narrow-line region (NLR) component at rest, and therefore a large part of the high-ionization NLR is affected by the outflow. Given the radio loudness of these NLS1 galaxies, the observations are consistent with a pole on view onto their central engines, so that the effects of polar outflows are maximized. In addition, a very efficient driving mechanism is required, to reach the high observed velocities. We explore implications from recent hydrodynamic simulations of the interaction between fast winds or jets with the large-scale NLR. Overall, the best agreement with observations (and especially the high outflow speeds of the [NeV] emitting gas) can be reached if the NLS1 galaxies are relatively young sources with lifetimes not much exceeding 1 Myr. These systems represent sites of strong feedback at NLR scales at work, well below redshift one.

  14. Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

    Directory of Open Access Journals (Sweden)

    H. Nakajima

    2006-01-01

    Full Text Available Centrifuge modeling of one-step outflow tests were carried out using a 2-m radius geotechnical centrifuge, and the cumulative outflow and transient pore water pressure were measured during the tests at multiple gravity levels. Based on the scaling laws of centrifuge modeling, the measurements generally showed reasonable agreement with prototype data calculated from forward simulations with input parameters determined from standard laboratory tests. The parameter optimizations were examined for three different combinations of input data sets using the test measurements. Within the gravity level examined in this study up to 40g, the optimized unsaturated parameters compared well when accurate pore water pressure measurements were included along with cumulative outflow as input data. With its capability to implement variety of instrumentations under well controlled initial and boundary conditions and to shorten testing time, the centrifuge modeling technique is attractive as an alternative experimental method that provides more freedom to set inverse problem conditions for the parameter estimation.

  15. Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

    Science.gov (United States)

    Nakajima, H.; Stadler, A. T.

    2006-10-01

    Centrifuge modeling of one-step outflow tests were carried out using a 2-m radius geotechnical centrifuge, and the cumulative outflow and transient pore water pressure were measured during the tests at multiple gravity levels. Based on the scaling laws of centrifuge modeling, the measurements generally showed reasonable agreement with prototype data calculated from forward simulations with input parameters determined from standard laboratory tests. The parameter optimizations were examined for three different combinations of input data sets using the test measurements. Within the gravity level examined in this study up to 40g, the optimized unsaturated parameters compared well when accurate pore water pressure measurements were included along with cumulative outflow as input data. With its capability to implement variety of instrumentations under well controlled initial and boundary conditions and to shorten testing time, the centrifuge modeling technique is attractive as an alternative experimental method that provides more freedom to set inverse problem conditions for the parameter estimation.

  16. The Red Sea outflow regulated by the Indian monsoon

    Science.gov (United States)

    Aiki, Hidenori; Takahashi, Keiko; Yamagata, Toshio

    2006-08-01

    To investigate why the Red Sea water overflows less in summer and more in winter, we have developed a locally high-resolution global OGCM with transposed poles in the Arabian peninsula and India. Based on a series of sensitivity experiments with different sets of idealized atmospheric forcing, the present study shows that the summer cessation of the strait outflow is remotely induced by the monsoonal wind over the Indian Ocean, in particular that over the western Arabian Sea. During the southwest monsoon (May-September), thermocline in the Gulf of Aden shoals as a result of coastal Ekman upwelling induced by the predominantly northeastward wind in the Gulf of Aden and the Arabian Sea. Because this shoaling is maximum during the southwest summer monsoon, the Red Sea water is blocked at the Bab el Mandeb Strait by upwelling of the intermediate water of the Gulf of Aden in late summer. The simulation also shows the three-dimensional evolution of the Red Sea water tongue at the mid-depths in the Gulf of Aden. While the tongue meanders, the discharged Red Sea outflow water (RSOW) (incoming Indian Ocean intermediate water (IOIW)) is always characterized by anticyclonic (cyclonic) vorticity, as suggested from the potential vorticity difference.

  17. Ultrafast Outflows: Galaxy-scale Active Galactic Nucleus Feedback

    Science.gov (United States)

    Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

    2013-01-01

    We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

  18. ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, A. Y.; Umemura, M. [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577 (Japan); Bicknell, G. V., E-mail: ayw@ccs.tsukuba.ac.jp [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

    2013-01-20

    We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

  19. ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK

    International Nuclear Information System (INIS)

    Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

    2013-01-01

    We show, using global three-dimensional grid-based hydrodynamical simulations, that ultrafast outflows (UFOs) from active galactic nuclei (AGNs) result in considerable feedback of energy and momentum into the interstellar medium (ISM) of the host galaxy. The AGN wind interacts strongly with the inhomogeneous, two-phase ISM consisting of dense clouds embedded in a tenuous, hot, hydrostatic medium. The outflow floods through the intercloud channels, sweeps up the hot ISM, and ablates and disperses the dense clouds. The momentum of the UFO is primarily transferred to the dense clouds via the ram pressure in the channel flow, and the wind-blown bubble evolves in the energy-driven regime. Any dependence on UFO opening angle disappears after the first interaction with obstructing clouds. On kpc scales, therefore, feedback by UFOs operates similarly to feedback by relativistic AGN jets. Negative feedback is significantly stronger if clouds are distributed spherically rather than in a disk. In the latter case, the turbulent backflow of the wind drives mass inflow toward the central black hole. Considering the common occurrence of UFOs in AGNs, they are likely to be important in the cosmological feedback cycles of galaxy formation.

  20. Screen Channel Liquid Acquisition Device Outflow Tests in Liquid Hydrogen

    Science.gov (United States)

    Hartwig, Jason W.; Chato, David J.; McQuillen, J. B.; Vera, J.; Kudlac, M. T.; Quinn, F. D.

    2013-01-01

    This paper presents experimental design and test results of the recently concluded 1-g inverted vertical outflow testing of two 325x2300 full scale liquid acquisition device (LAD) channels in liquid hydrogen (LH2). One of the channels had a perforated plate and internal cooling from a thermodynamic vent system (TVS) to enhance performance. The LADs were mounted in a tank to simulate 1-g outflow over a wide range of LH2 temperatures (20.3 - 24.2 K), pressures (100 - 350 kPa), and flow rates (0.010 - 0.055 kg/s). Results indicate that the breakdown point is dominated by liquid temperature, with a second order dependence on mass flow rate through the LAD. The best performance is always achieved in the coldest liquid states for both channels, consistent with bubble point theory. Higher flow rates cause the standard channel to break down relatively earlier than the TVS cooled channel. Both the internal TVS heat exchanger and subcooling the liquid in the propellant tank are shown to significantly improve LAD performance.

  1. Quenching star formation with quasar outflows launched by trapped IR radiation

    Science.gov (United States)

    Costa, Tiago; Rosdahl, Joakim; Sijacki, Debora; Haehnelt, Martin G.

    2018-06-01

    We present cosmological radiation-hydrodynamic simulations, performed with the code RAMSES-RT, of radiatively-driven outflows in a massive quasar host halo at z = 6. Our simulations include both single- and multi-scattered radiation pressure on dust from a quasar and are compared against simulations performed with thermal feedback. For radiation pressure-driving, we show that there is a critical quasar luminosity above which a galactic outflow is launched, set by the equilibrium of gravitational and radiation forces. While this critical luminosity is unrealistically high in the single-scattering limit for plausible black hole masses, it is in line with a ≈ 3 × 10^9 M_⊙ black hole accreting at its Eddington limit, if infrared (IR) multi-scattering radiation pressure is included. The outflows are fast (v ≳ 1000 km s^{-1}) and strongly mass-loaded with peak mass outflow rates ≈ 10^3 - 10^4 M_⊙ yr^{-1}, but short-lived (star formation in the bulge. We hence argue that radiation pressure-driven feedback may be an important ingredient in regulating star formation in compact starbursts, especially during the quasar's `obscured' phase.

  2. Production Planning with Respect to Uncertainties. Simulator Based Production Planning of Average Sized Combined Heat and Power Production Plants; Produktionsplanering under osaekerhet. Simulatorbaserad produktionsplanering av medelstora kraftvaermeanlaeggningar

    Energy Technology Data Exchange (ETDEWEB)

    Haeggstaahl, Daniel [Maelardalen Univ., Vaesteraas (Sweden); Dotzauer, Erik [AB Fortum, Stockholm (Sweden)

    2004-12-01

    Production planning in Combined Heat and Power (CHP) systems is considered. The focus is on development and use of mathematical models and methods. Different aspects on production planning are discussed, including weather and load predictions. Questions relevant on the different planning horizons are illuminated. The main purpose with short-term (one week) planning is to decide when to start and stop the production units, and to decide how to use the heat storage. The main conclusion from the outline of pros and cons of commercial planning software are that several are using Mixed Integer Programming (MIP). In that sense they are similar. Building a production planning model means that the planning problem is formulated as a mathematical optimization problem. The accuracy of the input data determines the practical detail level of the model. Two alternatives to the methods used in today's commercial programs are proposed: stochastic optimization and simulator-based optimization. The basic concepts of mathematical optimization are outlined. A simulator-based model for short-term planning is developed. The purpose is to minimize the production costs, depending on the heat demand in the district heating system, prices of electricity and fuels, emission taxes and fees, etc. The problem is simplified by not including any time-linking conditions. The process model is developed in IPSEpro, a heat and mass-balance software from SimTech Simulation Technology. TOMLAB, an optimization toolbox in MATLAB, is used as optimizer. Three different solvers are applied: glcFast, glcCluster and SNOPT. The link between TOMLAB and IPSEpro is accomplished using the Microsoft COM technology. MATLAB is the automation client and contains the control of IPSEpro and TOMLAB. The simulator-based model is applied to the CHP plant in Eskilstuna. Two days are chosen and analyzed. The optimized production is compared to the measured. A sensitivity analysis on how variations in outdoor

  3. Silo outflow of soft frictionless spheres

    Science.gov (United States)

    Ashour, Ahmed; Trittel, Torsten; Börzsönyi, Tamás; Stannarius, Ralf

    2017-12-01

    Outflow of granular materials from silos is a remarkably complex physical phenomenon that has been extensively studied with simple objects like monodisperse hard disks in two dimensions (2D) and hard spheres in 2D and 3D. For those materials, empirical equations were found that describe the discharge characteristics. Softness adds qualitatively new features to the dynamics and to the character of the flow. We report a study of the outflow of soft, practically frictionless hydrogel spheres from a quasi-2D bin. Prominent features are intermittent clogs, peculiar flow fields in the container, and a pronounced dependence of the flow rate and clogging statistics on the container fill height. The latter is a consequence of the ineffectiveness of Janssen's law: the pressure at the bottom of a bin containing hydrogel spheres grows linearly with the fill height.

  4. Hot Accretion onto Black Holes with Outflow

    Directory of Open Access Journals (Sweden)

    Park Myeong-Gu

    2018-01-01

    Full Text Available Classic Bondi accretion flow can be generalized to rotating viscous accretion flow. Study of hot accretion flow onto black holes show that its physical charateristics change from Bondi-like for small gas angular momentum to disk-like for Keperian gas angular momentum. Especially, the mass accretion rate divided by the Bondi accretion rate is proportional to the viscosity parameter alpha and inversely proportional to the gas angular momentum divided by the Keplerian angular momentum at the Bondi radius for gas angular momentum comparable to the Keplerian value. The possible presence of outflow will increase the mass inflow rate at the Bondi radius but decrease the mass accretion rate across the black hole horizon by many orders of magnitude. This implies that the growth history of supermassive black holes and their coevolution with host galaxies will be dramatically changed when the accreted gas has angular momentum or develops an outflow.

  5. Another piece of the puzzle: The fast H I outflow in Mrk 231

    Science.gov (United States)

    Morganti, Raffaella; Veilleux, Sylvain; Oosterloo, Tom; Teng, Stacy H.; Rupke, David

    2016-09-01

    We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast H I 21 cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow H I absorption blueshifted ~1300 km s-1 with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15 × 1018Tspin cm-2. We derive the Tspin to lie in the range 400-2000 K and the corresponding H I densities are nHI ~ 10-100 cm-3. Our results complement previous findings and confirm the multiphase nature of the outflow in Mrk 231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the H I outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by Na I and molecular gas in this source. Our results suggest that an H I component is present in fast outflows regardless of the acceleration mechanism (wind vs. jet driven) and that it must be connected with common properties of the pre-interaction gas involved. Considering the observed similarity of their column densities, the H I outflow likely represents the inner part of the broad wind identified on larger scales in atomic Na I. The mass outflow rate of the H I outflow (between 8 and 18 M⊙ yr-1) does not appear to be as large as that observed in molecular gas, partly owing to the smaller sizes of the outflowing region sampled by the H I absorption. These characteristics are commonly seen in other cases of outflows driven by the active galactic nucleus (AGN) suggesting that the H I may represent a short intermediate phase in the rapid cooling of the gas. The results further confirm H I as a good tracer for AGN-driven outflows not only in powerful radio sources. We also obtained deeper continuum

  6. Neutron resonance averaging

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs

  7. Outflow Kinematics Manifested by the Hα Line: Gas Outflows in Type 2 AGNs. IV

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Daeun; Woo, Jong-Hak; Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2017-08-20

    Energetic ionized gas outflows driven by active galactic nuclei (AGNs) have been studied as a key phenomenon related to AGN feedback. To probe the kinematics of the gas in the narrow-line region, [O iii] λ 5007 has been utilized in a number of studies showing nonvirial kinematic properties due to AGN outflows. In this paper, we statistically investigate whether the H α emission line is influenced by AGN-driven outflows by measuring the kinematic properties based on the H α line profile and comparing them with those of [O iii]. Using the spatially integrated spectra of ∼37,000 Type 2 AGNs at z < 0.3 selected from the Sloan Digital Sky Survey DR7, we find a nonlinear correlation between H α velocity dispersion and stellar velocity dispersion that reveals the presence of the nongravitational component, especially for AGNs with a wing component in H α . The large H α velocity dispersion and velocity shift of luminous AGNs are clear evidence of AGN outflow impacts on hydrogen gas, while relatively smaller kinematic properties compared to those of [O iii] imply that the observed outflow effect on the H α line is weaker than the case of [O iii].

  8. Ensemble averaged multi-phase Eulerian model for columnar/equiaxed solidification of a binary alloy: II. Simulation of the columnar-to-equiaxed transition (CET)

    International Nuclear Information System (INIS)

    Ciobanas, A I; Fautrelle, Y

    2007-01-01

    A new multi-phase Eulerian model for the columnar and equiaxed dendritic solidification has been developed. In this paper we first focus on the numerical simulation of quasi-steady solidification experiments in order to obtain corresponding CET maps. We have identified three main zones on the CET map: the pure columnar, the pure equiaxed zone and finally the mixed columnar+equiaxed zone. The mixed c/e zone was further quantified by means of a columnar fraction ε c which quantifies in a rigorous way the two coexisting structures. Since it intrinsically includes the solutal and the mechanical blocking effects, the new ensemble model unifies the semi-empirical Hunt's approach (pure mechanical blocking mechanism) and the Martorano et al approach (pure solutal blocking mechanism). Secondly the present model was used to simulate unidirectional solidification experiments. It was found that the columnar front evolved in a quasi-steady state until a time very close to the critical CET moment. It is also found that the equiaxed nucleation undercooling is close to the maximum columnar dendrite tip undercooling and that the CET is virtually independent of the equiaxed zone ahead of the columnar front. If the equiaxed zone is not taken into account it is observed that the columnar front velocity exhibits a sudden increase at the beginning of the solidification followed by a quasi-plateau corresponding to a quasi-state at the columnar tips and finally, above a critical time, an oscillatory evolution. The beginning of the oscillatory evolution of the columnar front was well correlated with the CET position measured in the experiments. We also find that this oscillatory evolution of the columnar front is very favourable for the fragmentation of the columnar dendrites and thus for the CET. In this respect, it seems that the unsteady regime of the columnar front with respect to the local cooling conditions represents the main cause for the CET phenomena, at least for the non

  9. Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Chi-Ho [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Krolik, Julian H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2017-07-01

    Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply toward the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.

  10. Supernova blast wave within a stellar cluster outflow

    Science.gov (United States)

    Rodríguez-Ramírez, J. C.; Raga, A. C.; Velázquez, P. F.; Rodríguez-González, A.; Toledo-Roy, J. C.

    2014-11-01

    In this paper, we develop a semi-analytic model of a supernova which goes off in the centre of a stellar cluster. The supernova remnant interacts with a stratified, pre-existent outflow produced by the winds of the cluster stars. We compare our semi-analytic model with numerical simulations using the spherically symmetric Euler equations with appropriate mass and energy source terms. We find good agreement between these two approaches, and we find that for typical parameters the blast wave is likely to reach the Taylor-Sedov regime outside the cluster radius. We also calculate the predicted X-ray luminosity of the flow as a function of time, and we obtain its dependence on the outer radius and the number of stars of the cluster.

  11. How to average logarithmic retrievals?

    Directory of Open Access Journals (Sweden)

    B. Funke

    2012-04-01

    Full Text Available Calculation of mean trace gas contributions from profiles obtained by retrievals of the logarithm of the abundance rather than retrievals of the abundance itself are prone to biases. By means of a system simulator, biases of linear versus logarithmic averaging were evaluated for both maximum likelihood and maximum a priori retrievals, for various signal to noise ratios and atmospheric variabilities. These biases can easily reach ten percent or more. As a rule of thumb we found for maximum likelihood retrievals that linear averaging better represents the true mean value in cases of large local natural variability and high signal to noise ratios, while for small local natural variability logarithmic averaging often is superior. In the case of maximum a posteriori retrievals, the mean is dominated by the a priori information used in the retrievals and the method of averaging is of minor concern. For larger natural variabilities, the appropriateness of the one or the other method of averaging depends on the particular case because the various biasing mechanisms partly compensate in an unpredictable manner. This complication arises mainly because of the fact that in logarithmic retrievals the weight of the prior information depends on abundance of the gas itself. No simple rule was found on which kind of averaging is superior, and instead of suggesting simple recipes we cannot do much more than to create awareness of the traps related with averaging of mixing ratios obtained from logarithmic retrievals.

  12. Analysis of Influence of the Thermal Dependence of Air Thermophysical Properties on the Accuracy of Simulation of Heat Transfer in a Turbulent Flow in Case of Applying Different Methods of Averaging Navier-Stokes Equations

    Directory of Open Access Journals (Sweden)

    A. D. Kliukvin

    2014-01-01

    Full Text Available There is theoretically investigated the influence of thermal dependence of air thermophysical properties on accuracy of heat transfer problems solution in a turbulent flow when using different methods of averaging the Navier-Stokes equations.There is analyzed the practicability of using particular method of averaging the NavierStokes equations when it’s necessary to clarify the solution of heat transfer problem taking into account the variability of air thermophysical properties.It’s shown that Reynolds and Favre averaging (the most common methods of averaging the Navier-Stokes equations are not effective in this case because these methods inaccurately describe behavior of large scale turbulent structures which strongly depends on geometry of particular flow. Thus it’s necessary to use more universal methods of turbulent flow simulation which are not based on averaging of all turbulent scales.In the article it’s shown that instead of Reynold and Favre averaging it’s possible to use large eddy simulation whereby turbulent structures are divided into small-scale and large-scale ones with subsequent modelling of small-scale ones only. But this approach leads to the necessarity of increasing the computational power by 2-3 orders.For different methods of averaging the form of additional terms of averaged Navier-Stokes equations in case of accounting pulsation of thermophysical properties of the air is obtained.On the example of a submerged heated air jet the errors (which occur when neglecting the thermal dependence of air thermophysical properties on averaged flow temperature in determination of convectional and conductive components of heat flux and viscous stresses are evaluated. It’s shown that the greatest increase of solution accuracy can be obtained in case of the flows with high temperature gradients.Finally using infinite Teylor series it’s found that underestimation of convective and conductive components of heat flux and

  13. Ergodic averages via dominating processes

    DEFF Research Database (Denmark)

    Møller, Jesper; Mengersen, Kerrie

    2006-01-01

    We show how the mean of a monotone function (defined on a state space equipped with a partial ordering) can be estimated, using ergodic averages calculated from upper and lower dominating processes of a stationary irreducible Markov chain. In particular, we do not need to simulate the stationary...... Markov chain and we eliminate the problem of whether an appropriate burn-in is determined or not. Moreover, when a central limit theorem applies, we show how confidence intervals for the mean can be estimated by bounding the asymptotic variance of the ergodic average based on the equilibrium chain....

  14. ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Lockman, F. J. [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States); Dickey, J. M. [School of Physics and Mathematics, University of Tasmania, TAS 7001 (Australia); Gaensler, B. M.; Green, A. J., E-mail: naomi.mcclure-griffiths@csiro.au [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

    2013-06-10

    We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

  15. Iodine-131 monitoring in sewage plant outflow

    International Nuclear Information System (INIS)

    McGowan, D R; Crawley, M T; Pratt, B E; Hinton, P J; Peet, D J

    2014-01-01

    Three different hospital sites (Oxford, Sutton and Guildford) have performed sampling of their local sewage plant outflow to determine levels of radioactivity resulting from iodine-131 patients undergoing radionuclide therapies. It was found that a maximum of 20% of activity discharged from the hospitals was present in the sewage plant final effluent channel. This is significantly below the level predicted by mathematical models in current use. The results further show that abatement systems to reduce public exposure are unlikely to be warranted at hospital sites. (paper)

  16. New noninvasive treatment for prostate outflow obstruction

    International Nuclear Information System (INIS)

    Richards, D.; Milroy, E.; Chapple, C.; Eldin, A.; Wallstein, H.

    1989-01-01

    Sixteen patients with prostatic outflow obstruction underwent implantation of the Wallstent endoprothesis, a woven mesh of fine stainless steel, mounted on a 9-F delivery system with an unconstrained diameter of 14 mm. The stent was inserted under local anesthesia, and placement was guided by linear transrectal US and flexible urethroscopy. In no patient was the distal sphincter mechanism compromised. In four, stent balloon dilation was needed. Urodynamic parameters (especially flow rate, voiding detrusor pressure, and postvoid residual) improved in all patients. Our experience showed the Wallstent endoprosthesis to be a safe, clinically acceptable, and minimally invasive alternative to prostatectomy

  17. Interferometric Mapping of Perseus Outflows with MASSES

    Science.gov (United States)

    Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

    2017-01-01

    The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

  18. ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

    International Nuclear Information System (INIS)

    McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S.; Lockman, F. J.; Dickey, J. M.; Gaensler, B. M.; Green, A. J.

    2013-01-01

    We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of ∼14 km s –1 , and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at ∼200 km s –1 in a Galactic wind.

  19. Inferring Polar Ion Outflows from Topside Ionograms

    Science.gov (United States)

    Sojka, J. J.; Rice, D. D.; Eccles, V.; Schunk, R. W.; David, M.; Benson, R. F.; James, H. G.

    2017-12-01

    The high-latitude topside ionosphere is dominated by O+ ions from the F-region peak around 300 km to over 1000 km altitude. The O+ profile shape provides information on the thermal structure, field aligned plasma dynamics, and outflows into the magnetosphere. Topside electron density profiles (EDP) are either obtained from topside sounders or Incoherent Scatter Radars. There is a large archive of topside sounder ionograms and hand scaled EDPs from the Alouette and ISIS satellites between 1962 and 1990. Recent NASA data enhancement efforts have augmented these EDP archives by producing digital topside ionograms both from the 7-track analog telemetry tapes and from 35 mm topside film ionograms. Rice et al [2017] in their 35 mm ionogram recovery emphasized high latitude ionograms taken during disturbed conditions. The figure below contrasts ISIS-II EDPs extracted from 35 mm films before and during a major storm (Dst -200nT) on 9 April 1972 (left panel: quiet period before the storm; right panel: during the peak of the storm). Both satellite passes used for these EDPs were centered on the Resolute Bay location that in 1972 was close to the magnetic pole. They begin at auroral latitudes around 2100 MLT and end on the dayside around 0900MLT. We will present results of how ionospheric models replicate both the quiet and disturbed conditions shown in the figure. Three types of models will be contrasted: an empirical ionosphere (IRI), a physics based ionospheric model (TDIM), and a fluid-based polar-wind model (PW). During the storm pass, when it is expected that substantial heating is present, the ISIS-II topside EDPs provide severe constraints on the usage of these models. These constraints enable estimates of the outflow fluxes as well as the heating that has occurred. The comparisons with the empirical model establish how well the pre-storm topside is modeled and identifies the challenges as the storm magnitude increases. The physics-based TDIM does have storm drivers

  20. GGD 37: AN EXTREME PROTOSTELLAR OUTFLOW

    International Nuclear Information System (INIS)

    Green, J. D.; Watson, D. M.; Forrest, W. J.; Kim, K. H.; Bergin, E.; Maret, S.; Melnick, G.; Tolls, V.; Sonnentrucker, P.; Sargent, B. A.; Raines, S. N.

    2011-01-01

    We present the first Spitzer-IRS spectral maps of the Herbig-Haro flow GGD 37 detected in lines of [Ne III], [O IV], [Ar III], and [Ne V]. The detection of extended [O IV] (55 eV) and some extended emission in [Ne V] (97 eV) indicates a shock temperature in excess of 100,000 K, in agreement with X-ray observations, and a shock speed in excess of 200 km s -1 . The presence of an extended photoionization or collisional ionization region indicates that GGD 37 is a highly unusual protostellar outflow.

  1. Compact binary merger and kilonova: outflows from remnant disc

    Science.gov (United States)

    Yi, Tuan; Gu, Wei-Min; Liu, Tong; Kumar, Rajiv; Mu, Hui-Jun; Song, Cui-Ying

    2018-05-01

    Outflows launched from a remnant disc of compact binary merger may have essential contribution to the kilonova emission. Numerical calculations are conducted in this work to study the structure of accretion flows and outflows. By the incorporation of limited-energy advection in the hyper-accretion discs, outflows occur naturally from accretion flows due to imbalance between the viscous heating and the sum of the advective and radiative cooling. Following this spirit, we revisit the properties of the merger outflow ejecta. Our results show that around 10-3 ˜ 10-1 M⊙ of the disc mass can be launched as powerful outflows. The amount of unbound mass varies with the disc mass and the viscosity. The outflow-contributed peak luminosity is around 1040 ˜ 1041 erg s-1. Such a scenario can account for the observed kilonovae associated with short gamma-ray bursts, including the recent event AT2017gfo (GW170817).

  2. Effect of clear cutting on snow accumulation and water outflow at Fraser, Colorado

    Directory of Open Access Journals (Sweden)

    C. A. Troendle

    1997-01-01

    Full Text Available This paper compares of snowpack accumulation and ablation, evapotranspiration, and water outflow from clearcut and forested plots within a high elevation (2900 m mixed conifer forest at the Fraser Experimental Forest near Fraser, Colorado, USA. Also presented is a method for defining contributing area where outflow is measured from unbounded plots. Plots were monitored from 1980 to 1990 and again in 1993. The clearcut plot was harvested in late 1984. Evapotranspiration (ET of the forested plot at zero discharge (ETo was estimated at 426 mm while the ET was 500 mm at the mean precipitation of 596 mm. ET was dependent on precipitation with about 28% of precipitation input in excess of 426 mm contributing to increased ET, while the remainder contributed to increased outflow. During the six monitored post-harvest years, Peak Water Equivalent of the snowpack averaged 36% higher on the cut plot than on the control, and the mean discharge increased from 85 mm to 356 mm. Area estimates were obtained from the slopes of the regression of outflow on precipitation inputs. Hydrologic parameters corresponded closely to those previously determined at Fraser Experimental Forest using other methods, lending credence to the validity of the area estimates.

  3. Misalignment of Magnetic Fields and Outflows in Protostellar Cores

    OpenAIRE

    Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erika; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.

    2013-01-01

    We present results of λ1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with ~2."5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotati...

  4. Molecular outflows in the L1641 region of Orion

    International Nuclear Information System (INIS)

    Morgan, J.A.

    1990-01-01

    Little is known about the interaction between molecular outflows associated with young stellar objects and the parent molecular cloud that produced them. This is because molecular outflows are a recently discovered phenomenon and, so, have not had their global properties studied in great detail and molecular clouds were not mapped to sufficiently high spatial resolution to resolve the interaction. The interaction between molecular outflows and the L1641 molecular cloud is addressed by both identifying and mapping all the molecular outflows as well as the detailed structure of the cloud. Candidate molecular outflows were found from single point 12-CO observations of young stellar objects identified from the IRAS survey data. The candidate sources were then mapped to confirm their molecular outflow nature. From these maps, molecular outflow characteristics such as their morphology, orientation, and energetics were determined. In addition, the Orion molecular cloud was mapped to compare directly with the molecular outflows. The molecular outflows identified were found to have rising infrared spectra, radio continuum emission that suggests a stellar wind or optically thick H II region, and molecular line strengths that indicate that they are embedded within a very dense environment. The lack of an optical counterpart for many molecular outflows suggests that they occur at the earliest stages of stellar evolution. The lack of an optical counterpart for many molecular outflows suggest that they occur at the earliest stages of stellar evolution. The orientations of the molecular outflows appear to lie in no preferred direction and they have shapes that indicate that the molecular cloud is responsible for determining their direction and collimation

  5. Circumstellar Disks and Outflows in Turbulent Molecular Cloud Cores: Possible Formation Mechanism for Misaligned Systems

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Tomoaki [Faculty of Sustainability Studies, Hosei University, Fujimi, Chiyoda-ku, Tokyo 102-8160 (Japan); Machida, Masahiro N. [Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Inutsuka, Shu-ichiro, E-mail: matsu@hosei.ac.jp [Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan)

    2017-04-10

    We investigate the formation of circumstellar disks and outflows subsequent to the collapse of molecular cloud cores with the magnetic field and turbulence. Numerical simulations are performed by using an adaptive mesh refinement to follow the evolution up to ∼1000 years after the formation of a protostar. In the simulations, circumstellar disks are formed around the protostars; those in magnetized models are considerably smaller than those in nonmagnetized models, but their size increases with time. The models with stronger magnetic fields tend to produce smaller disks. During evolution in the magnetized models, the mass ratios of a disk to a protostar is approximately constant at ∼1%–10%. The circumstellar disks are aligned according to their angular momentum, and the outflows accelerate along the magnetic field on the 10–100 au scale; this produces a disk that is misaligned with the outflow. The outflows are classified into two types: a magnetocentrifugal wind and a spiral flow. In the latter, because of the geometry, the axis of rotation is misaligned with the magnetic field. The magnetic field has an internal structure in the cloud cores, which also causes misalignment between the outflows and the magnetic field on the scale of the cloud core. The distribution of the angular momentum vectors in a core also has a non-monotonic internal structure. This should create a time-dependent accretion of angular momenta onto the circumstellar disk. Therefore, the circumstellar disks are expected to change their orientation as well as their sizes in the long-term evolutions.

  6. Studying the outflow-core interaction with ALMA Cycle 1 observations of the HH 46/47 molecular outflow

    Science.gov (United States)

    Zhang, Yichen; Arce, Hector G.; Mardones, Diego; Dunham, Michael; Garay, Guido; Noriega-Crespo, Alberto; Corder, Stuartt; Offner, Stella; Cabrit, Sylvie

    2016-01-01

    We present ALMA Cycle 1 observations of the HH 46/47 molecular outflow which is driven by a low-mass Class 0/I protostar. Previous ALMA Cycle 0 12CO observation showed outflow cavities produced by the entrainment of ambient gas by the protostellar jet and wide-angle wind. Here we present analysis of observation of 12CO, 13CO, C18O and other species using combined 12m array and ACA observations. The improved angular resolution and sensitivity allow us to detect details of the outflow structure. Specially, we see that the outflow cavity wall is composed of two or more layers of outflowing gas, which separately connect to different shocked regions along the outflow axis inside the cavity, suggesting the outflow cavity wall is composed of multiple shells entrained by a series of jet bow-shock events. The new 13CO and C18O data also allow us to trace relatively denser and slower outflow material than that traced by the 12CO. These species are only detected within about 1 to 2 km/s from the cloud velocity, tracing the outflow to lower velocities than what is possible using only the 12CO emission. Interestingly, the cavity wall of the red lobe appears at very low outflow velocities (as low as ~0.2 km/s). In addition, 13CO and C18O allow us to correct for the CO optical depth, allowing us to obtain more accurate estimates of the outflow mass, momentum and kinetic energy. Applying the optical depth correction significantly increases the previous mass estimate by a factor of 14. The outflow kinetic energy distribution shows that even though the red lobe is mainly entrained by jet bow-shocks, most of the outflow energy is being deposited into the cloud at the base of the outflow cavity rather than around the heads of the bow shocks. The estimated total mass, momentum, and energy of the outflow indicate that the outflow has the ability to disperse the parent core. We found possible evidence for a slowly moving rotating outflow in CS. Our 13CO and C18O observations also trace a

  7. DISCOVERY OF RELATIVISTIC OUTFLOW IN THE SEYFERT GALAXY Ark 564

    International Nuclear Information System (INIS)

    Gupta, A.; Mathur, S.; Krongold, Y.; Nicastro, F.

    2013-01-01

    We present Chandra High Energy Transmission Grating Spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low-velocity outflow components usually observed in Seyfert galaxies. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here, we present identifications of the strongest lines as Kα transitions of O VII (two lines) and O VI at outflow velocities of ∼0.1c. These lines are detected at 6.9σ, 6.2σ, and 4.7σ, respectively, and cannot be due to chance statistical fluctuations. Photoionization models with ultra-high velocity components improve the spectral fit significantly, providing further support for the presence of relativistic outflow in this source. Without knowing the location of the absorber, its mass and energy outflow rates cannot be well constrained; we find E-dot (outflow)/L bol lower limit of ≥0.006% assuming a bi-conical wind geometry. This is the first time that absorption lines with ultra-high velocities are unambiguously detected in the soft X-ray band. The presence of outflows with relativistic velocities in active galactic nuclei (AGNs) with Seyfert-type luminosities is hard to understand and provides valuable constraints to models of AGN outflows. Radiation pressure is unlikely to be the driving mechanism for such outflows and magnetohydrodynamic may be involved

  8. The energetics of AGN radiation pressure-driven outflows

    Science.gov (United States)

    Ishibashi, W.; Fabian, A. C.; Maiolino, R.

    2018-05-01

    The increasing observational evidence of galactic outflows is considered as a sign of active galactic nucleus (AGN) feedback in action. However, the physical mechanism responsible for driving the observed outflows remains unclear, and whether it is due to momentum, energy, or radiation is still a matter of debate. The observed outflow energetics, in particular the large measured values of the momentum ratio (\\dot{p}/(L/c) ˜ 10) and energy ratio (\\dot{E}_k/L ˜ 0.05), seems to favour the energy-driving mechanism; and most observational works have focused their comparison with wind energy-driven models. Here, we show that AGN radiation pressure on dust can adequately reproduce the observed outflow energetics (mass outflow rate, momentum flux, and kinetic power), as well as the scalings with luminosity, provided that the effects of radiation trapping are properly taken into account. In particular, we predict a sublinear scaling for the mass outflow rate (\\dot{M} ∝ L^{1/2}) and a superlinear scaling for the kinetic power (\\dot{E}_k ∝ L^{3/2}), in agreement with the observational scaling relations reported in the most recent compilation of AGN outflow data. We conclude that AGN radiative feedback can account for the global outflow energetics, at least equally well as the wind energy-driving mechanism, and therefore both physical models should be considered in the interpretation of future AGN outflow observations.

  9. ALMA OBSERVATIONS OF THE HH 46/47 MOLECULAR OUTFLOW

    International Nuclear Information System (INIS)

    Arce, Héctor G.; Mardones, Diego; Garay, Guido; Corder, Stuartt A.; Noriega-Crespo, Alberto; Raga, Alejandro C.

    2013-01-01

    The morphology, kinematics, and entrainment mechanism of the HH 46/47 molecular outflow were studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly different. We argue that these differences are partly due to contrasting ambient densities that result in different wind components having a distinct effect on the entrained gas in each lobe. A 29 point mosaic, covering the two lobes at an angular resolution of about 3'', detected outflow emission at much higher velocities than previous observations, resulting in significantly higher estimates of the outflow momentum and kinetic energy than previous studies of this source, using the CO(1-0) line. The morphology and the kinematics of the gas in the blue lobe are consistent with models of outflow entrainment by a wide-angle wind, and a simple model describes the observed structures in the position-velocity diagram and the velocity-integrated intensity maps. The red lobe exhibits a more complex structure, and there is evidence that this lobe is entrained by a wide-angle wind and a collimated episodic wind. Three major clumps along the outflow axis show velocity distribution consistent with prompt entrainment by different bow shocks formed by periodic mass ejection episodes which take place every few hundred years. Position-velocity cuts perpendicular to the outflow cavity show gradients where the velocity increases toward the outflow axis, inconsistent with outflow rotation. Additionally, we find evidence for the existence of a small outflow driven by a binary companion

  10. The three-dimensional properties and energetics of radio-jet-driven outflows

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Hsin-Yi; Stockton, Alan, E-mail: hsshih@ifa.hawaii.edu, E-mail: stockton@ifa.hawaii.edu [Institute for Astronomy, University of Hawai' i 2680 Woodlawn Dr, Honolulu, HI 96822 (United States)

    2014-05-01

    Extended emission-line regions (EELRs), found around radio-loud sources, are likely outflows driven by one form of powerful active galactic nucleus (AGN) feedback mechanism. We seek to constrain the three-dimensional gas properties and the outflow energetics of the EELRs in this study. We used an integral field unit to observe EELRs around two samples of radio-loud AGNs with similar radio properties, but different orientations: a sample of quasars and a sample of radio galaxies. A morphological comparison suggests a scenario where the three-dimensional EELR gas distribution follows rough biconical shapes with wide opening angles. The average extent of the EELRs is ∼18.5 kpc. The estimated average mass of the EELRs, with reasonable assumptions for gas densities, is ∼3 × 10{sup 8} M {sub ☉}, and the average mass outflow rate is ∼30 M {sub ☉} yr{sup –1}. The EELRs around quasars and radio galaxies share similar kinematic properties. Both samples have velocity structures that display a range of complexities, they do not appear to correlate with the jet orientations, and both span a similar range of velocity dispersions. Around 30% of the detected EELRs show large-scale rotational motions, which may have originated from recent mergers involving gas-rich disk galaxies.

  11. Measurement of Outflow Facility Using iPerfusion.

    Directory of Open Access Journals (Sweden)

    Joseph M Sherwood

    Full Text Available Elevated intraocular pressure (IOP is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied

  12. Energetic molecular outflow near AFGL 961: millimeter-wave and infrared observations

    International Nuclear Information System (INIS)

    Lada, C.J.; Gautier, T.N. III

    1982-01-01

    We report detailed millimeter-wave and near-infrared spectroscopy of the dynamically active region around the infrared source AFGL 961, near the Rosette nebula. Millimeter-wave 12 CO observations are used to study the high-velocity molecular flow around AFGL 961. These observations show that the high-velocity flow has a maximum extent of at least 6' or 2.9 pc at the distance of AFGL 961. The flow is found to be anisotropic, with redshifted high-velocity emission considerably more extended than blueshifted high-velocity emission. However, the flow does not appear to be as highly collimated as some other sources of high-velocity bipolar outflow. We also find the emission profiles to be asymmetric in velocity such that the integrated intensity of the redshifted high-velocity emission is on average 2.5 times greater than that of the blueshifted emission. The mass of the gas involved in the flow is determined to be approximately 19 M/sub sun/, and the kinetic energy of this gas is estimated to be about 8 x 10 46 ergs. These observations are interpreted as evidence that an energetic bipolar outflow of molecular gas is occurring near AFGL 961. The momentum of the outflowing molecular gas is large, and it is shown that this places strong constraints on possible physical mechanisms which may be driving the outflow. The near-infrared spectrum of AFGL 961 from 1.4-2.4 μm was obtained in order to study the conditions immediately around the infrared source which may be driving the molecular outflow

  13. LOW-ALTITUDE RECONNECTION INFLOW-OUTFLOW OBSERVATIONS DURING A 2010 NOVEMBER 3 SOLAR ERUPTION

    Energy Technology Data Exchange (ETDEWEB)

    Savage, Sabrina L.; Holman, Gordon; Su, Yang [NASA/Goddard Space Flight Center, Oak Ridge Associated Universities, 8800 Greenbelt Road, Code 671, Greenbelt, MD 20771 (United States); Reeves, Katharine K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS 58, Cambridge, MA 02138 (United States); Seaton, Daniel B. [Royal Observatory of Belgium-SIDC, Avenue Circulaire 3, B-1180 Brussels (Belgium); McKenzie, David E. [Department of Physics, Montana State University, P.O. Box 173840, Bozeman, MT 59717-3840 (United States)

    2012-07-20

    For a solar flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion-an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from {approx}150 to 690 km s{sup -1} with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfven speeds, we estimate the Alfvenic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal light curve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be {approx}10{sup 2} km s{sup -1} with outflow speeds ranging from {approx}10{sup 2} to 10{sup 3} km s{sup -1}-indicating acceleration during the reconnection process. The fastest of these outflows are in the form of apparently traveling density enhancements along the legs of the loops rather than the loop apexes themselves. These flows could possibly either be accelerated plasma, shocks, or waves prompted by reconnection. The measurements presented here show an order of magnitude difference between the retraction speeds of the loops and the speed of the density enhancements within the loops-presumably exiting the reconnection site.

  14. LOW-ALTITUDE RECONNECTION INFLOW-OUTFLOW OBSERVATIONS DURING A 2010 NOVEMBER 3 SOLAR ERUPTION

    International Nuclear Information System (INIS)

    Savage, Sabrina L.; Holman, Gordon; Su, Yang; Reeves, Katharine K.; Seaton, Daniel B.; McKenzie, David E.

    2012-01-01

    For a solar flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion—an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from ∼150 to 690 km s –1 with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfvén speeds, we estimate the Alfvénic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal light curve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be ∼10 2 km s –1 with outflow speeds ranging from ∼10 2 to 10 3 km s –1 —indicating acceleration during the reconnection process. The fastest of these outflows are in the form of apparently traveling density enhancements along the legs of the loops rather than the loop apexes themselves. These flows could possibly either be accelerated plasma, shocks, or waves prompted by reconnection. The measurements presented here show an order of magnitude difference between the retraction speeds of the loops and the speed of the density enhancements within the loops—presumably exiting the reconnection site.

  15. Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers

    Science.gov (United States)

    Wu, Meng-Ru; Fernández, Rodrigo; Martínez-Pinedo, Gabriel; Metzger, Brian D.

    2016-12-01

    We consider r-process nucleosynthesis in outflows from black hole accretion discs formed in double neutron star and neutron star-black hole mergers. These outflows, powered by angular momentum transport processes and nuclear recombination, represent an important - and in some cases dominant - contribution to the total mass ejected by the merger. Here we calculate the nucleosynthesis yields from disc outflows using thermodynamic trajectories from hydrodynamic simulations, coupled to a nuclear reaction network. We find that outflows produce a robust abundance pattern around the second r-process peak (mass number A ˜ 130), independent of model parameters, with significant production of A spike at A = 132 that is absent in the Solar system r-process distribution. The spike arises from convection in the disc and depends on the treatment of nuclear heating in the simulations. We conclude that disc outflows provide an important - and perhaps dominant - contribution to the r-process yields of compact binary mergers, and hence must be included when assessing the contribution of these systems to the inventory of r-process elements in the Galaxy.

  16. Average male and female virtual dummy model (BioRID and EvaRID) simulations with two seat concepts in the Euro NCAP low severity rear impact test configuration.

    Science.gov (United States)

    Linder, Astrid; Holmqvist, Kristian; Svensson, Mats Y

    2018-05-01

    Soft tissue neck injuries, also referred to as whiplash injuries, which can lead to long term suffering accounts for more than 60% of the cost of all injuries leading to permanent medical impairment for the insurance companies, with respect to injuries sustained in vehicle crashes. These injuries are sustained in all impact directions, however they are most common in rear impacts. Injury statistics have since the mid-1960s consistently shown that females are subject to a higher risk of sustaining this type of injury than males, on average twice the risk of injury. Furthermore, some recently developed anti-whiplash systems have revealed they provide less protection for females than males. The protection of both males and females should be addresses equally when designing and evaluating vehicle safety systems to ensure maximum safety for everyone. This is currently not the case. The norm for crash test dummies representing humans in crash test laboratories is an average male. The female part of the population is not represented in tests performed by consumer information organisations such as NCAP or in regulatory tests due to the absence of a physical dummy representing an average female. Recently, the world first virtual model of an average female crash test dummy was developed. In this study, simulations were run with both this model and an average male dummy model, seated in a simplified model of a vehicle seat. The results of the simulations were compared to earlier published results from simulations run in the same test set-up with a vehicle concepts seat. The three crash pulse severities of the Euro NCAP low severity rear impact test were applied. The motion of the neck, head and upper torso were analysed in addition to the accelerations and the Neck Injury Criterion (NIC). Furthermore, the response of the virtual models was compared to the response of volunteers as well as the average male model, to that of the response of a physical dummy model. Simulations

  17. Unicameral bone cyst: radiographic assessment of venous outflow by cystography as a prognostic index.

    Science.gov (United States)

    Ramirez, Ana; Abril, Juan Carlos; Touza, Alberto

    2012-11-01

    The aim of this study was to determine the benefits of cystography in the management of a simple bone cyst, its implication in the final result of the treatment after corticoid intracystic injections, and the presence of secondary effects. We retrospectively reviewed 42 patients diagnosed with a simple bone cyst. Cystography was performed before the corticoid injection. The presence or absence of loculation intracyst and the existence and number of venous outflows were determined. According to the venous drainage, cysts were classified as type 0 when a venous outflow did not exist and as type 1 when there was a rapid venous outflow (unicameral bone cyst with absent loculation in 16 cases (37.3%), whereas the lesion showed multiloculation in 26 cases (62.7%). There was no statistical difference between loculation intracyst (present or absent) and the final outcomes of the 42 cysts treated with a steroid injection (P=0.9). Cystography showed a negative venogram in 10 cases (23.8%), whereas the cysts showed a rapid venous outflow in 32 cases (76.2%). On the basis of Neer's classification, all patients with a negative venogram achieved complete healing of the cyst. Patients with a rapid venous outflow achieved complete healing in 14 cases (Neer I). In two patients, the healing was incomplete at the end of the follow-up period (Neer IV). In most cases (21 cysts), healing was partial (Neer II). Five patients showed a recurrence after initial healing of the cyst (Neer III) (P<0.05). The number or the size of veins did not affect healing of a bone cyst (P=0.6). Two patients with a rapid venous outflow showed a generalized hypertrichosis after the first injection of corticosteroids. Sex and age at the initiation of the first injection were not significant factors of healing (P=0.4). The average follow-up time was 59 months (24-60 months). Cystography provides morphological and functional information of simple bone cyst. It is a useful test before the administration of

  18. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belo...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion......In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...

  19. Enhanced ion acoustic fluctuations and ion outflows

    Directory of Open Access Journals (Sweden)

    F. R. E. Forme

    1999-02-01

    Full Text Available A number of observations showing enhanced ion acoustic echoes observed by means of incoherent scatter radars have been reported in the literature. The received power is extremely enhanced by up to 1 or 2 orders of magnitude above usual values, and it is mostly contained in one of the two ion acoustic lines. This spectral asymmetry and the intensity of the received signal cannot be resolved by the standard analysis procedure and often causes its failure. As a result, and in spite of a very clear spectral signature, the analysis is unable to fit the plasma parameters inside the regions of ion acoustic turbulence. We present European Incoherent Scatter radar (EISCAT observations of large ion outflows associated with the simultaneous occurrence of enhanced ion acoustic echoes. The ion fluxes can reach 1014 m-2 s-1 at 800 km altitude. From the very clear spectral signatures of these echoes, a method is presented to extract estimates of the electron temperature and the ion drift within the turbulent regions. It is shown that the electron gas is strongly heated up to 11 000 K. Also electron temperature gradients of about 0.02 K/m exist. Finally, the estimates of the electron temperature and of the ion drift are used to study the possible implications for the plasma transport inside turbulent regions. It is shown that strong electron temperature gradients cause enhancement of the ambipolar electric field and can account for the observed ion outflows.Key words. Ionosphere (auroral ionosphere; ionosphere · magnetosphere interactions; plasma waves and instabilities.

  20. The impact of remittances outflows on the economy of Poland

    OpenAIRE

    LASTOVETSKA ROKSOLANA ORESTIVNA

    2015-01-01

    The impact of remittances outflows on the economy of Poland is analyzed in the article. Based on historical data the vector autoregression model (VAR) was built to examine the effects of the sharp rise in the volume of remittances outflows. The model results are presented for the next macroeconomic indicators: GDP, inflation, interest rate and exchange rate.

  1. DSMC simulation of feed jet flow in gas centrifuge

    International Nuclear Information System (INIS)

    Jiang Dongjun; Zeng Shi

    2011-01-01

    Feed jet flow acts an important role for the counter-current in gas centrifuge. Direct simulation Monte-Carlo (DSMC) method was adopted to simulate the structure of the radial feed jet model. By setting the proper boundary conditions and the collision model of molecules, the flow distributions of the 2D radial feed jet were acquired under different feed conditions, including the wave structure of feed jet and the profile of the flow parameters. The analyses of the calculation results note the following flow phenomena: Near the radial outflow boundary, the obvious peaks of the flow parameters exist; higher speed of feed gas brings stronger influence on the flow field of the centrifuge; including the density, pressure and velocity of the gas, the distribution of the temperature is affected by the feed jet, at the outflow boundary, temperature to double times of the average value. (authors)

  2. Averaged RMHD equations

    International Nuclear Information System (INIS)

    Ichiguchi, Katsuji

    1998-01-01

    A new reduced set of resistive MHD equations is derived by averaging the full MHD equations on specified flux coordinates, which is consistent with 3D equilibria. It is confirmed that the total energy is conserved and the linearized equations for ideal modes are self-adjoint. (author)

  3. Determining average yarding distance.

    Science.gov (United States)

    Roger H. Twito; Charles N. Mann

    1979-01-01

    Emphasis on environmental and esthetic quality in timber harvesting has brought about increased use of complex boundaries of cutting units and a consequent need for a rapid and accurate method of determining the average yarding distance and area of these units. These values, needed for evaluation of road and landing locations in planning timber harvests, are easily and...

  4. Average Revisited in Context

    Science.gov (United States)

    Watson, Jane; Chick, Helen

    2012-01-01

    This paper analyses the responses of 247 middle school students to items requiring the concept of average in three different contexts: a city's weather reported in maximum daily temperature, the number of children in a family, and the price of houses. The mixed but overall disappointing performance on the six items in the three contexts indicates…

  5. Averaging operations on matrices

    Indian Academy of Sciences (India)

    2014-07-03

    Jul 3, 2014 ... Role of Positive Definite Matrices. • Diffusion Tensor Imaging: 3 × 3 pd matrices model water flow at each voxel of brain scan. • Elasticity: 6 × 6 pd matrices model stress tensors. • Machine Learning: n × n pd matrices occur as kernel matrices. Tanvi Jain. Averaging operations on matrices ...

  6. Average-energy games

    Directory of Open Access Journals (Sweden)

    Patricia Bouyer

    2015-09-01

    Full Text Available Two-player quantitative zero-sum games provide a natural framework to synthesize controllers with performance guarantees for reactive systems within an uncontrollable environment. Classical settings include mean-payoff games, where the objective is to optimize the long-run average gain per action, and energy games, where the system has to avoid running out of energy. We study average-energy games, where the goal is to optimize the long-run average of the accumulated energy. We show that this objective arises naturally in several applications, and that it yields interesting connections with previous concepts in the literature. We prove that deciding the winner in such games is in NP inter coNP and at least as hard as solving mean-payoff games, and we establish that memoryless strategies suffice to win. We also consider the case where the system has to minimize the average-energy while maintaining the accumulated energy within predefined bounds at all times: this corresponds to operating with a finite-capacity storage for energy. We give results for one-player and two-player games, and establish complexity bounds and memory requirements.

  7. Experimental assessment of valve performance in healthy and diseased right ventricular outflow tracts using magnetic resonance velocimetry

    Science.gov (United States)

    Schiavone, Nicole; Elkins, Christopher; McElhinney, Doff; Eaton, John K.; Marsden, Alison

    2017-11-01

    Tetralogy of Fallot (ToF), the most common type of cyanotic congenital heart defect, affects 1 in every 2500 newborns annually and typically requires surgical repair of the right ventricular outflow tract (RVOT) and placement of an artificial pulmonary valve. All artificial valves are subject to dysfunction, but their longevity is highly variable. Clinical observation reveals large variations in RVOT anatomy in ToF patients, which may affect longevity. This work aims to experimentally assess the performance of artificial pulmonary valves in anatomically realistic healthy and diseased RVOT geometries using magnetic resonance velocimetry (MRV). With MRV, we can capture 3D, three-component, phase-averaged velocity fields in 3D printed RVOT geometries. The experiment is designed to ensure physiological flow rate and pressure waveforms, while the RVOT geometries are based on anatomies seen clinically in ToF patients. Two models are used in the current work: an idealized RVOT based on healthy subjects aged eleven to thirteen and a diseased geometry with a dilation of 150% in vessel diameter downstream of the pulmonary valve. We will also present preliminary rigid-wall blood flow simulations in each model, towards the ultimate goal of experimental validation of valve simulations.

  8. The Origin of Fast Molecular Outflows in Quasars: Molecule Formation in AGN-Driven Galactic Winds

    Science.gov (United States)

    Richings, Alexander James; Faucher-Giguere, Claude-Andre

    2017-07-01

    Observations of AGN host galaxies have detected fast molecular outflows, with velocities up to 1000 km s-1. However, the origin of these molecular outflows is currently unclear. One possibility is that they are formed from molecular gas that is swept up from the host galaxy by the AGN wind. However, previous studies have suggested that molecular clouds that are swept up by an AGN wind are unlikely to survive being accelerated to such high velocities. An alternative scenario is that molecules may form within the AGN wind material itself. We present a suite of 3D hydrodynamic simulations of an idealised AGN wind that we have run to explore this scenario. These simulations are coupled to a time-dependent chemical model to follow the creation and destruction of molecules, including H2, CO, OH and HCO+. We find that molecules do form within the wind, with molecular outflow rates up to 140 M⊙ yr-1 after 1 Myr. This is sensitive to the ambient ISM density, metallicity, and AGN luminosity. We also compute observable CO emission lines from these simulations using a radiative transfer code in post-processing. The CO-derived outflow rates are comparable to those seen in observations, although the maximum line of sight velocities are a factor ≍2 lower than observed. We find a CO (1-0) to H2 conversion factor of αCO = 0.15 M⊙ (K km s-1 pc2)-1 at solar metallicity, 5 times lower than is typically assumed in observations of such systems.

  9. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    2001-01-01

    In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong ...... approximations to the Riemannian metric, and that the subsequent corrections are inherent in the least squares estimation.......In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...

  10. Forecasting Inflow and Outflow of Money Currency in East Java Using a Hybrid Exponential Smoothing and Calendar Variation Model

    Science.gov (United States)

    Susanti, Ana; Suhartono; Jati Setyadi, Hario; Taruk, Medi; Haviluddin; Pamilih Widagdo, Putut

    2018-03-01

    Money currency availability in Bank Indonesia can be examined by inflow and outflow of money currency. The objective of this research is to forecast the inflow and outflow of money currency in each Representative Office (RO) of BI in East Java by using a hybrid exponential smoothing based on state space approach and calendar variation model. Hybrid model is expected to generate more accurate forecast. There are two studies that will be discussed in this research. The first studies about hybrid model using simulation data that contain pattern of trends, seasonal and calendar variation. The second studies about the application of a hybrid model for forecasting the inflow and outflow of money currency in each RO of BI in East Java. The first of results indicate that exponential smoothing model can not capture the pattern calendar variation. It results RMSE values 10 times standard deviation of error. The second of results indicate that hybrid model can capture the pattern of trends, seasonal and calendar variation. It results RMSE values approaching the standard deviation of error. In the applied study, the hybrid model give more accurate forecast for five variables : the inflow of money currency in Surabaya, Malang, Jember and outflow of money currency in Surabaya and Kediri. Otherwise, the time series regression model yields better for three variables : outflow of money currency in Malang, Jember and inflow of money currency in Kediri.

  11. AGN outflows as neutrino sources: an observational test

    Science.gov (United States)

    Padovani, P.; Turcati, A.; Resconi, E.

    2018-04-01

    We test the recently proposed idea that outflows associated with Active Galactic Nuclei (AGN) could be neutrino emitters in two complementary ways. First, we cross-correlate a list of 94 "bona fide" AGN outflows with the most complete and updated repository of IceCube neutrinos currently publicly available, assembled by us for this purpose. It turns out that AGN with outflows matched to an IceCube neutrino have outflow and kinetic energy rates, and bolometric powers larger than those of AGN with outflows not matched to neutrinos. Second, we carry out a statistical analysis on a catalogue of [O III] λ5007 line profiles using a sample of 23,264 AGN at z values (˜6 and 18 per cent respectively, pre-trial) for relatively high velocities and luminosities. Our results are consistent with a scenario where AGN outflows are neutrino emitters but at present do not provide a significant signal. This can be tested with better statistics and source stacking. A predominant role of AGN outflows in explaining the IceCube data appears in any case to be ruled out.

  12. Density diagnostics of ionized outflows in active galacitc nuclei

    Science.gov (United States)

    Mao, J.; Kaastra, J.; Mehdipour, M.; Raassen, T.; Gu, L.

    2017-10-01

    Ionized outflows in Active Galactic Nuclei are thought to influence their nuclear and local galactic environment. However, the distance of outflows with respect to the central engine is poorly constrained, which limits our understanding of the kinetic power by the outflows. Therefore, the impact of AGN outflows on their host galaxies is uncertain. Given the density of the outflows, their distance can be immediately obtained by the definition of the ionization parameter. Here we carry out a theoretical study of density diagnostics of AGN outflows using absorption lines from metastable levels in Be-like to F-like ions. With the new self-consistent photoionization model (PION) in the SPEX code, we are able to calculate ground and metastable level populations. This enable us to determine under what physical conditions these levels are significantly populated. We then identify characteristic transitions from these metastable levels in the X-ray band. Firm detections of absorption lines from such metastable levels are challenging for current grating instruments. The next generation of spectrometers like X-IFU onboard Athena will certainly identify the presence/absence of these density- sensitive absorption lines, thus tightly constraining the location and the kinetic power of AGN outflows.

  13. A Monte Carlo simulation study comparing linear regression, beta regression, variable-dispersion beta regression and fractional logit regression at recovering average difference measures in a two sample design.

    Science.gov (United States)

    Meaney, Christopher; Moineddin, Rahim

    2014-01-24

    In biomedical research, response variables are often encountered which have bounded support on the open unit interval--(0,1). Traditionally, researchers have attempted to estimate covariate effects on these types of response data using linear regression. Alternative modelling strategies may include: beta regression, variable-dispersion beta regression, and fractional logit regression models. This study employs a Monte Carlo simulation design to compare the statistical properties of the linear regression model to that of the more novel beta regression, variable-dispersion beta regression, and fractional logit regression models. In the Monte Carlo experiment we assume a simple two sample design. We assume observations are realizations of independent draws from their respective probability models. The randomly simulated draws from the various probability models are chosen to emulate average proportion/percentage/rate differences of pre-specified magnitudes. Following simulation of the experimental data we estimate average proportion/percentage/rate differences. We compare the estimators in terms of bias, variance, type-1 error and power. Estimates of Monte Carlo error associated with these quantities are provided. If response data are beta distributed with constant dispersion parameters across the two samples, then all models are unbiased and have reasonable type-1 error rates and power profiles. If the response data in the two samples have different dispersion parameters, then the simple beta regression model is biased. When the sample size is small (N0 = N1 = 25) linear regression has superior type-1 error rates compared to the other models. Small sample type-1 error rates can be improved in beta regression models using bias correction/reduction methods. In the power experiments, variable-dispersion beta regression and fractional logit regression models have slightly elevated power compared to linear regression models. Similar results were observed if the

  14. Outflow and hot dust emission in broad absorption line quasars

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shaohua; Zhou, Hongyan [Polar Research Institute of China, 451 Jinqiao Road, Shanghai 200136 (China); Wang, Huiyuan; Wang, Tinggui; Xing, Feijun; Jiang, Peng [Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhang, Kai, E-mail: zhangshaohua@pric.gov.cn, E-mail: whywang@mail.ustc.edu.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

    2014-05-01

    We have investigated a sample of 2099 broad absorption line (BAL) quasars with z = 1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature and is refined by our new algorithm. Correlations of outflow velocity and strength with a hot dust indicator (β{sub NIR}) and other quasar physical parameters—such as an Eddington ratio, luminosity, and a UV continuum slope—are explored in order to figure out which parameters drive outflows. Here β{sub NIR} is the near-infrared continuum slope, which is a good indicator of the amount of hot dust emission relative to the accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depend on the Eddington ratio, UV slope, and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with β{sub NIR} in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasars. The statistical analysis and composite spectra study both reveal that outflow strength and velocity are more strongly correlated with β{sub NIR} than the Eddington ratio, luminosity, and UV slope. In particular, the composites show that the entire C IV absorption profile shifts blueward and broadens as β{sub NIR} increases, while the Eddington ratio and UV slope only affect the high and low velocity part of outflows, respectively. We discuss several potential processes and suggest that the dusty outflow scenario, i.e., that dust is intrinsic to outflows and may contribute to the outflow acceleration, is most likely.

  15. Average Bandwidth Allocation Model of WFQ

    Directory of Open Access Journals (Sweden)

    Tomáš Balogh

    2012-01-01

    Full Text Available We present a new iterative method for the calculation of average bandwidth assignment to traffic flows using a WFQ scheduler in IP based NGN networks. The bandwidth assignment calculation is based on the link speed, assigned weights, arrival rate, and average packet length or input rate of the traffic flows. We prove the model outcome with examples and simulation results using NS2 simulator.

  16. ALMA Studies of the Disk-Jet-Outflow Connection

    Science.gov (United States)

    Dougados, Catherine; Louvet, F.; Mardones, D.; Cabrit, S.

    2017-06-01

    I will describe in this contribution recent results obtained with ALMA on the origin of the disk/jet/outflow connexion in T Tauri stars. I will first present ALMA observations of the disk associated with the jet source Th 28, which question previous jet rotation measurements in this source and the implications drawn from them. I will then discuss Cycle 2 ALMA observations of the disk and small scale CO outflow associated with the prototypical edge-on HH 30 source. The unprecedented angular resolution of this dataset brings new constraints on the origin of the CO outflows in young stars.

  17. Average is Over

    Science.gov (United States)

    Eliazar, Iddo

    2018-02-01

    The popular perception of statistical distributions is depicted by the iconic bell curve which comprises of a massive bulk of 'middle-class' values, and two thin tails - one of small left-wing values, and one of large right-wing values. The shape of the bell curve is unimodal, and its peak represents both the mode and the mean. Thomas Friedman, the famous New York Times columnist, recently asserted that we have entered a human era in which "Average is Over" . In this paper we present mathematical models for the phenomenon that Friedman highlighted. While the models are derived via different modeling approaches, they share a common foundation. Inherent tipping points cause the models to phase-shift from a 'normal' bell-shape statistical behavior to an 'anomalous' statistical behavior: the unimodal shape changes to an unbounded monotone shape, the mode vanishes, and the mean diverges. Hence: (i) there is an explosion of small values; (ii) large values become super-large; (iii) 'middle-class' values are wiped out, leaving an infinite rift between the small and the super large values; and (iv) "Average is Over" indeed.

  18. THE BARYON CYCLE AT HIGH REDSHIFTS: EFFECTS OF GALACTIC WINDS ON GALAXY EVOLUTION IN OVERDENSE AND AVERAGE REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Sadoun, Raphael [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112-0830 (United States); Shlosman, Isaac; Choi, Jun-Hwan; Romano-Díaz, Emilio, E-mail: raphael.sadoun@utah.edu [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)

    2016-10-01

    We employ high-resolution cosmological zoom-in simulations focusing on a high-sigma peak and an average cosmological field at z ∼ 6–12 in order to investigate the influence of environment and baryonic feedback on galaxy evolution in the reionization epoch. Strong feedback, e.g., galactic winds, caused by elevated star formation rates (SFRs) is expected to play an important role in this evolution. We compare different outflow prescriptions: (i) constant wind velocity (CW), (ii) variable wind scaling with galaxy properties (VW), and (iii) no outflows (NW). The overdensity leads to accelerated evolution of dark matter and baryonic structures, absent from the “normal” region, and to shallow galaxy stellar mass functions at the low-mass end. Although CW shows little dependence on the environment, the more physically motivated VW model does exhibit this effect. In addition, VW can reproduce the observed specific SFR (sSFR) and the sSFR–stellar mass relation, which CW and NW fail to satisfy simultaneously. Winds also differ substantially in affecting the state of the intergalactic medium (IGM). The difference lies in the volume-filling factor of hot, high-metallicity gas, which is near unity for CW, while such gas remains confined in massive filaments for VW, and locked up in galaxies for NW. Such gas is nearly absent from the normal region. Although all wind models suffer from deficiencies, the VW model seems to be promising in correlating the outflow properties with those of host galaxies. Further constraints on the state of the IGM at high z are needed to separate different wind models.

  19. The combined effect of AGN and supernovae feedback in launching massive molecular outflows in high-redshift galaxies

    Science.gov (United States)

    Biernacki, Pawel; Teyssier, Romain

    2018-04-01

    We have recently improved our model of active galactic nucleus (AGN) by attaching the supermassive black hole (SMBH) to a massive nuclear star cluster (NSC). Here, we study the effects of this new model in massive, gas-rich galaxies with several simulations of different feedback recipes with the hydrodynamics code RAMSES. These simulations are compared to a reference simulation without any feedback, in which the cooling halo gas is quickly consumed in a burst of star formation. In the presence of strong supernovae (SN) feedback, we observe the formation of a galactic fountain that regulates star formation over a longer period, but without halting it. If only AGN feedback is considered, as soon as the SMBH reaches a critical mass, strong outflows of hot gas are launched and prevent the cooling halo gas from reaching the disc, thus efficiently halting star formation, leading to the so-called `quenching'. If both feedback mechanisms act in tandem, we observe a non-linear coupling, in the sense that the dense gas in the supernovae-powered galactic fountain is propelled by the hot outflow powered by the AGN at much larger radii than without AGN. We argue that these particular outflows are able to unbind dense gas from the galactic halo, thanks to the combined effect of SN and AGN feedback. We speculate that this mechanism occurs at the end of the fast growing phase of SMBH, and is at the origin of the dense molecular outflows observed in many massive high-redshift galaxies.

  20. Investigation of cerebral venous outflow in microgravity.

    Science.gov (United States)

    Taibi, A; Gadda, G; Gambaccini, M; Menegatti, E; Sisini, F; Zamboni, P

    2017-10-31

    The gravitational gradient is the major component to face when considering the physiology of venous return, and there is a growing interest in understanding the mechanisms ensuring the heart filling, in the absence of gravity, for astronauts who perform long-term space missions. The purpose of the Drain Brain project was to monitor the cerebral venous outflow of a crew member during an experiment on the International Space Station (ISS), so as to study the compensatory mechanisms that facilitate this essential physiological action in subjects living in a microgravity environment. Such venous function has been characterized by means of a novel application of strain-gauge plethysmography which uses a capacitive sensor. In this contribution, preliminary results of our investigation have been presented. In particular, comparison of plethysmography data confirmed that long duration spaceflights lead to a redistribution of venous blood volume, and showed interesting differences in the amplitude of cardiac oscillations measured at the level of the neck veins. The success of the experiment has also demonstrated that thanks to its easy portability, non-invasiveness, and non-operator dependence, the proposed device can be considered as a novel tool for use aboard the ISS. Further trials are now under way to complete the investigation on the drainage function of the neck veins in microgravity.

  1. Modeling the Quiet Time Outflow Solution in the Polar Cap

    Science.gov (United States)

    Glocer, Alex

    2011-01-01

    We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum, The PWOM solves the gyrotropic transport equations for O(+), H(+), and He(+) along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. [2011] of electron density, which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites (Kitamura et al. [2011]). The data and model agree reasonably well. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide validation of the PWOM's ability to model the quiet time ((background" solution.

  2. AGN Outflow Shocks on Bonnor–Ebert Spheres

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, Zachary; Silk, Joseph; Rahman, Mubdi [The Johns Hopkins University Department of Physics and Astronomy, Bloomberg Center for Physics and Astronomy, Room 366, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Gaibler, Volker [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Bieri, Rebekka [Institut d’Astrophysique de Paris, UMR 7095, CNRS, UPMC Univ. Paris VI, 98 bis Boulevard Arago, F-75014 Paris (France)

    2017-04-20

    Feedback from active galactic nuclei (AGNs) and subsequent jet cocoons and outflow bubbles can have a significant impact on star formation in the host galaxy. To investigate feedback physics on small scales, we perform hydrodynamic simulations of realistically fast AGN winds striking Bonnor–Ebert spheres and examine gravitational collapse and ablation. We test AGN wind velocities ranging from 300 to 3000 km s{sup −1} and wind densities ranging from 0.5 to 10 m {sub p} cm{sup −3}. We include heating and cooling of low- and high-temperature gas, self-gravity, and spatially correlated perturbations in the shock, with a maximum resolution of 0.01 pc. We find that the ram pressure is the most important factor that determines the fate of the cloud. High ram pressure winds increase fragmentation and decrease the star formation rate, but they also cause star formation to occur on a much shorter timescale and with increased velocities of the newly formed stars. We find a threshold ram pressure of ∼2 × 10{sup −8} dyn cm{sup −2} above which stars are not formed because the resulting clumps have internal velocities large enough to prevent collapse. Our results indicate that simultaneous positive and negative feedback will be possible in a single galaxy, as AGN wind parameters will vary with location within a galaxy.

  3. Average nuclear surface properties

    International Nuclear Information System (INIS)

    Groote, H. von.

    1979-01-01

    The definition of the nuclear surface energy is discussed for semi-infinite matter. This definition is extended also for the case that there is a neutron gas instead of vacuum on the one side of the plane surface. The calculations were performed with the Thomas-Fermi Model of Syler and Blanchard. The parameters of the interaction of this model were determined by a least squares fit to experimental masses. The quality of this fit is discussed with respect to nuclear masses and density distributions. The average surface properties were calculated for different particle asymmetry of the nucleon-matter ranging from symmetry beyond the neutron-drip line until the system no longer can maintain the surface boundary and becomes homogeneous. The results of the calculations are incorporated in the nuclear Droplet Model which then was fitted to experimental masses. (orig.)

  4. Americans' Average Radiation Exposure

    International Nuclear Information System (INIS)

    2000-01-01

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body

  5. Ultra-Fast Outflows in Radio-Loud AGN: New Constraints on Jet-Disk Connection

    Science.gov (United States)

    Sambruna, Rita

    There is strong observational and theoretical evidence that outflows/jets are coupled to accretion disks in black hole accreting systems, from Galactic to extragalactic sizes. While in radio-quiet AGN there is ample evidence for the presence of Ultra-Fast Outflows (UFOs) from the presence of blue-shifted absorption features in their 4-10~keV spectra, sub-relativistic winds are expected on theoretical basis in radio-loud AGN but have not been observed until now. Our recent Suzaku observations of 5 bright Broad- Line Radio Galaxies (BLRGs, the radio-loud counterparts of Seyferts) has started to change this picture. We found strong evidence for UFOs in 3 out of 5 BLRGs, with ionization parameters, column densities, and velocities of the absorber similar to Seyferts. Moreover, the outflows in BLRGs are likely to be energetically very significant: from the Suzaku data of the three sources, outflow masses similar to the accretion masses and kinetic energies of the wind similar to the X-ray luminosity and radio power of the jet are inferred. Clearly, UFOs in radio-loud AGN represent a new key ingredient to understand their central engines and in particular, the jet-disk linkage. Our discovery of UFOs in a handful of BLRGs raises the questions of how common disk winds are in radio-loud AGN, what the absorber physical and dynamical characteristics are, and what is the outflow role in broader picture of galaxy-black hole connection for radio sources, i.e., for large-scale feedback models. To address these and other issues, we propose to use archival XMM-Newton and Suzaku spectra to search for Ultra-Fast Outflows in a large number of radio sources. Over a period of two years, we will conduct a systematic, uniform analysis of the archival X-ray data, building on our extensive experience with a similar previous project for Seyferts, and using robust analysis and statistical methodologies. As an important side product, we will also obtain accurate, self- consistent measurements

  6. Cumulative neutrino background from quasar-driven outflows

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiawei; Loeb, Abraham, E-mail: xiawei.wang@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-12-01

    Quasar-driven outflows naturally account for the missing component of the extragalactic γ-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons. We study the simultaneous neutrino emission by the same protons. We adopt outflow parameters that best fit the extragalactic γ-ray background data and derive a cumulative neutrino background of ∼ 10{sup −7} GeV cm{sup −2} s{sup −1} sr{sup −1} at neutrino energies E {sub ν} ∼> 10 TeV, which naturally explains the most recent IceCube data without tuning any free parameters. The link between the γ-ray and neutrino emission from quasar outflows can be used to constrain the high-energy physics of strong shocks at cosmological distances.

  7. Characterization of molecular outflows in the substellar domain

    International Nuclear Information System (INIS)

    Phan-Bao, Ngoc; Dang-Duc, Cuong; Lee, Chin-Fei; Ho, Paul T. P.; Li, Di

    2014-01-01

    We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J = 2 → 1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M J , which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf position is detected. The redshifted gas lobe that is elongated in the northeast direction suggests a possible bipolar outflow from the source with a position angle of about 36°. Assuming that the redshifted emission is outflow emission from GM Tau, we then estimate a molecular outflow mass in the range from 1.9 × 10 –6 M ☉ to 2.9 × 10 –5 M ☉ and an outflow mass-loss rate from 2.7 × 10 –9 M ☉ yr –1 to 4.1 × 10 –8 M ☉ yr –1 . These values are comparable to those we have observed in the young brown dwarf ISO-Oph 102 of 60 M J in ρ Ophiuchi and the very low-mass star MHO 5 of 90 M J in Taurus. Our results suggest that the outflow process in very low-mass objects is episodic with a duration of a few thousand years and the outflow rate of active episodes does not significantly change for different stages of the formation process of very low-mass objects. This may provide us with important implications that clarify the formation process of brown dwarfs.

  8. Characterization of molecular outflows in the substellar domain

    Energy Technology Data Exchange (ETDEWEB)

    Phan-Bao, Ngoc; Dang-Duc, Cuong [Department of Physics, International University-Vietnam National University HCM, Block 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City (Viet Nam); Lee, Chin-Fei; Ho, Paul T. P. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Di, E-mail: pbngoc@hcmiu.edu.vn, E-mail: pbngoc@asiaa.sinica.edu.tw [National Astronomical Observatories, Chinese Academy of Science, Chaoyang District Datun Rd A20, Beijing (China)

    2014-11-01

    We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J = 2 → 1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M {sub J}, which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf position is detected. The redshifted gas lobe that is elongated in the northeast direction suggests a possible bipolar outflow from the source with a position angle of about 36°. Assuming that the redshifted emission is outflow emission from GM Tau, we then estimate a molecular outflow mass in the range from 1.9 × 10{sup –6} M {sub ☉} to 2.9 × 10{sup –5} M {sub ☉} and an outflow mass-loss rate from 2.7 × 10{sup –9} M {sub ☉} yr{sup –1} to 4.1 × 10{sup –8} M {sub ☉} yr{sup –1}. These values are comparable to those we have observed in the young brown dwarf ISO-Oph 102 of 60 M {sub J} in ρ Ophiuchi and the very low-mass star MHO 5 of 90 M {sub J} in Taurus. Our results suggest that the outflow process in very low-mass objects is episodic with a duration of a few thousand years and the outflow rate of active episodes does not significantly change for different stages of the formation process of very low-mass objects. This may provide us with important implications that clarify the formation process of brown dwarfs.

  9. Topographic control on the nascent Mediterranean outflow

    Science.gov (United States)

    Gasser, M.; Pelegrí, J. L.; Nash, J. D.; Peters, H.; García-Lafuente, J.

    2011-12-01

    Data collected during a 12-day cruise in July 2009 served to examine the structure of the nascent Mediterranean Outflow Water (MOW) immediately west of the Espartel Sill, the westernmost sill in the Strait of Gibraltar. The MOW is characterized by high salinities (>37.0 and reaching 38.3) and high velocities (exceeding 1 m s-1 at 100 m above the seafloor), and follows a submerged valley along a 30 km stretch, the natural western extension of the strait. It is approx. 150 m thick and 10 km wide, and experiences a substantial drop from 420 to 530 m over a distance of some 3 km between two relatively flat regions. Measurements indicate that the nascent MOW behaves as a gravity current with nearly maximal traveling speed; if this condition is maintained, then the maximum MOW velocity would decrease slowly with distance from the Espartel Sill, remaining significantly high until the gravity current excess density is only a small fraction of its original value. The sharp pycnocline between the Mediterranean and the overlying North Atlantic Central waters is dynamically unstable, particularly where the flow interacts with the 100 m decrease in bottom depth. Here, subcritical gradient Richardson numbers coincide with the development of large interfacial undulations and billows. The very energetic downslope flow is likely responsible for the development of a narrow V-shaped channel downstream of the seafloor drop along the axis of the submerged valley, this probably being the very first erosional scour produced by the nascent MOW. The coincidence of subcritical gradient Richardson numbers with relatively high turbidity values above the channel flanks suggests it may be undergoing upstream erosion.

  10. Quasar outflow energetics from broad absorption line variability

    Science.gov (United States)

    McGraw, S. M.; Shields, J. C.; Hamann, F. W.; Capellupo, D. M.; Herbst, H.

    2018-03-01

    Quasar outflows have long been recognized as potential contributors to the co-evolution between supermassive black holes (SMBHs) and their host galaxies. The role of outflows in active galactic nucleus (AGN) feedback processes can be better understood by placing observational constraints on wind locations and kinetic energies. We utilize broad absorption line (BAL) variability to investigate the properties of a sample of 71 BAL quasars with P V broad absorption. The presence of P V BALs indicates that other BALs like C IV are saturated, such that variability in those lines favours clouds crossing the line of sight. We use these constraints with measurements of BAL variability to estimate outflow locations and energetics. Our data set consists of multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory. We detect significant (4σ) BAL variations from 10 quasars in our sample over rest-frame time-scales between ≤0.2-3.8 yr. Our derived distances for the 10 variable outflows are nominally ≲ 1-10 pc from the SMBH using the transverse-motion scenario, and ≲ 100-1000 pc from the central source using ionization-change considerations. These distances, in combination with the estimated high outflow column densities (i.e. NH ≳ 1022 cm-2), yield outflow kinetic luminosities between ˜ 0.001 and 1 times the bolometric luminosity of the quasar, indicating that many absorber energies within our sample are viable for AGN feedback.

  11. Observations of the Evolution of Ion Outflow During a Sawtooth Event

    Science.gov (United States)

    Lund, E. J.; Nowrouzi, N.; Kistler, L. M.; Cai, X.; Frey, H. U.

    2015-12-01

    Sawtooth oscillations are one of several convection modes known to exist in the magnetosphere. Recent simulations have suggested that O+^+ ions transported from the high-latitude ionosphere to the magnetotail can drive sawtooth events. We present observational case studies of sawtooth events using data from FAST near the noon-midnight meridional plane, Cluster in the magnetotail, GOES and LANL energetic particle sensors at geosynchronous orbit, and ACE solar wind data to investigate the evolution of ion outflow during sawtooth events and the question of whether O+^+ outflow from one tooth helps to drive subsequent teeth. We find that oxygen enters the tail from the lobes after each tooth onset, the oxygen fraction in the magnetotail often increases after a tooth onset, and that the oxygen fraction of outflowing ions increases after a tooth event both in the cusp and on the nightside. However, a significant amount of low energy oxygen (≲1 keV) can end up in the dayside inner magnetosphere.

  12. A simple and efficient outflow boundary condition for the incompressible Navier–Stokes equations

    Directory of Open Access Journals (Sweden)

    Yibao Li

    2017-01-01

    Full Text Available Many researchers have proposed special treatments for outlet boundary conditions owing to lack of information at the outlet. Among them, the simplest method requires a large enough computational domain to prevent or reduce numerical errors at the boundaries. However, an efficient method generally requires special treatment to overcome the problems raised by the outlet boundary condition used. For example, mass flux is not conserved and the fluid field is not divergence-free at the outlet boundary. Overcoming these problems requires additional computational cost. In this paper, we present a simple and efficient outflow boundary condition for the incompressible Navier–Stokes equations, aiming to reduce the computational domain for simulating flow inside a long channel in the streamwise direction. The proposed outflow boundary condition is based on the transparent equation, where a weak formulation is used. The pressure boundary condition is derived by using the Navier–Stokes equations and the outlet flow boundary condition. In the numerical algorithm, a staggered marker-and-cell grid is used and temporal discretization is based on a projection method. The intermediate velocity boundary condition is consistently adopted to handle the velocity–pressure coupling. Characteristic numerical experiments are presented to demonstrate the robustness and accuracy of the proposed numerical scheme. Furthermore, the agreement of computational results from small and large domains suggests that our proposed outflow boundary condition can significantly reduce computational domain sizes.

  13. Hemodialysis Reliable Outflow (HeRO) device in end-stage dialysis access: a decision analysis model.

    Science.gov (United States)

    Dageforde, Leigh Anne; Bream, Peter R; Moore, Derek E

    2012-09-01

    The Hemodialysis Reliable Outflow (HeRO) dialysis access device is a permanent tunneled dialysis graft connected to a central venous catheter and is used in patients with end-stage dialysis access (ESDA) issues secondary to central venous stenosis. The safety and effectiveness of the HeRO device has previously been proven, but no study thus far has compared the cost of its use with tunneled dialysis catheters (TDCs) and thigh grafts in patients with ESDA. A decision analytic model was developed to simulate outcomes for patients with ESDA undergoing placement of a HeRO dialysis access device, TDC, or thigh graft. Outcomes of interest were infection, thrombosis, and ischemic events. Baseline values, ranges, and costs were determined from a systematic review of the literature. Total costs were based on 1 year of post-procedure outcomes. Sensitivity analyses were conducted to test model strength. The HeRO dialysis access device is the least costly dialysis access with an average 1-year cost of $6521. The 1-year cost for a TDC was $8477. A thigh graft accounted for $9567 in a 1-year time period. The HeRO dialysis access device is the least costly method of ESDA. The primary determinants of cost in this model are infection in TDCs and leg ischemia necessitating amputation in thigh grafts. Further study is necessary to incorporate patient preference and quality of life into the model. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. The right ventricular outflow tract in tetralogy of Fallot by preoperative cardiac angiography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Chul; Lee, Jung Sook; Yoo, Soo Woong; Yu, Hoe Sung; Kim, Han Suk [National Medical Center, Seoul (Korea, Republic of)

    1979-06-15

    The underdevelopment of the right ventricular outflow tract is the essence among the main components of the tetralogy of Fallot. The detail and exact information about the states of the outflow tract in each patients with tetralogy of Fallot are very important to cardiac surgery. Fourteen patients of tetralogy of Fallet (12 undergone open heart surgery and 2, palliative) are available for their clinical chart and for cardiac angiography reviews. Analysis of them focusing the right ventricular outflow tract discloses the following results: 1. Average ratios of the systole to diastole of the pulmonary infundibulum are 0.63 {+-} 0.03 with the range of 0.44 to 1.0 cm P-A, and 0.64 {+-} 0.12 with the range of 0.5 to 0.83 on lateral projections. These results indicate relatively fixed infundibular stenosis of TOF. 2. Average infundibular systole to pulmonary bulb ratios are 0.24 {+-} 0.05 on P-A, and 0.36 {+-} 0.17 on lateral projections, which mean the underdeveloped and narrowed infundibulum more than the pulmonary truck in TOF. 3. Average pulmonary to aortic bulb ratios are 0.59 {+-} 0.01 on P-A, 0.54 {+-} 0.01 on lateral projections. These suggest hypoplasia of the pulmonary truck and anteriorly displaced conus septum and truncus septum from a developmental point of view. 4. The overriding degree of the aorta in our series are from 25% to 50% by Kjellberg et al classification.

  15. The right ventricular outflow tract in tetralogy of Fallot by preoperative cardiac angiography

    International Nuclear Information System (INIS)

    Lee, Yong Chul; Lee, Jung Sook; Yoo, Soo Woong; Yu, Hoe Sung; Kim, Han Suk

    1979-01-01

    The underdevelopment of the right ventricular outflow tract is the essence among the main components of the tetralogy of Fallot. The detail and exact information about the states of the outflow tract in each patients with tetralogy of Fallot are very important to cardiac surgery. Fourteen patients of tetralogy of Fallet (12 undergone open heart surgery and 2, palliative) are available for their clinical chart and for cardiac angiography reviews. Analysis of them focusing the right ventricular outflow tract discloses the following results: 1. Average ratios of the systole to diastole of the pulmonary infundibulum are 0.63 ± 0.03 with the range of 0.44 to 1.0 cm P-A, and 0.64 ± 0.12 with the range of 0.5 to 0.83 on lateral projections. These results indicate relatively fixed infundibular stenosis of TOF. 2. Average infundibular systole to pulmonary bulb ratios are 0.24 ± 0.05 on P-A, and 0.36 ± 0.17 on lateral projections, which mean the underdeveloped and narrowed infundibulum more than the pulmonary truck in TOF. 3. Average pulmonary to aortic bulb ratios are 0.59 ± 0.01 on P-A, 0.54 ± 0.01 on lateral projections. These suggest hypoplasia of the pulmonary truck and anteriorly displaced conus septum and truncus septum from a developmental point of view. 4. The overriding degree of the aorta in our series are from 25% to 50% by Kjellberg et al classification.

  16. Flexible time domain averaging technique

    Science.gov (United States)

    Zhao, Ming; Lin, Jing; Lei, Yaguo; Wang, Xiufeng

    2013-09-01

    Time domain averaging(TDA) is essentially a comb filter, it cannot extract the specified harmonics which may be caused by some faults, such as gear eccentric. Meanwhile, TDA always suffers from period cutting error(PCE) to different extent. Several improved TDA methods have been proposed, however they cannot completely eliminate the waveform reconstruction error caused by PCE. In order to overcome the shortcomings of conventional methods, a flexible time domain averaging(FTDA) technique is established, which adapts to the analyzed signal through adjusting each harmonic of the comb filter. In this technique, the explicit form of FTDA is first constructed by frequency domain sampling. Subsequently, chirp Z-transform(CZT) is employed in the algorithm of FTDA, which can improve the calculating efficiency significantly. Since the signal is reconstructed in the continuous time domain, there is no PCE in the FTDA. To validate the effectiveness of FTDA in the signal de-noising, interpolation and harmonic reconstruction, a simulated multi-components periodic signal that corrupted by noise is processed by FTDA. The simulation results show that the FTDA is capable of recovering the periodic components from the background noise effectively. Moreover, it can improve the signal-to-noise ratio by 7.9 dB compared with conventional ones. Experiments are also carried out on gearbox test rigs with chipped tooth and eccentricity gear, respectively. It is shown that the FTDA can identify the direction and severity of the eccentricity gear, and further enhances the amplitudes of impulses by 35%. The proposed technique not only solves the problem of PCE, but also provides a useful tool for the fault symptom extraction of rotating machinery.

  17. Evidence for ultra-fast outflows in radio-quiet AGNs: III - location and energetics

    OpenAIRE

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-01-01

    Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultra-fast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ~0.0003-0.03pc (~10^2-10^4 r_s) from the central black hole, consistent with what is exp...

  18. The long lives of giant clumps and the birth of outflows in gas-rich galaxies at high redshift

    Energy Technology Data Exchange (ETDEWEB)

    Bournaud, Frédéric; Renaud, Florent; Daddi, Emanuele; Duc, Pierre-Alain; Elbaz, David; Gabor, Jared M.; Juneau, Stéphanie; Kraljic, Katarina; Le Floch' , Emeric [CEA, IRFU/SAp, F-91191 Gif-Sur-Yvette (France); Perret, Valentin; Amram, Philippe; Epinat, Benoit [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille), F-13388 Marseille (France); Dekel, Avishai [Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598 (United States); Elmegreen, Debra M. [Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States); Teyssier, Romain [Institute for Theoretical Physics, University of Zurich, CH-8057 Zurich (Switzerland)

    2014-01-01

    Star-forming disk galaxies at high redshift are often subject to violent disk instability, characterized by giant clumps whose fate is yet to be understood. The main question is whether the clumps disrupt within their dynamical timescale (≤50 Myr), like the molecular clouds in today's galaxies, or whether they survive stellar feedback for more than a disk orbital time (≈300 Myr) in which case they can migrate inward and help building the central bulge. We present 3.5-7 pc resolution adaptive mesh refinement simulations of high-redshift disks including photoionization, radiation pressure, and supernovae feedback. Our modeling of radiation pressure determines the mass loading and initial velocity of winds from basic physical principles. We find that the giant clumps produce steady outflow rates comparable to and sometimes somewhat larger than their star formation rate, with velocities largely sufficient to escape the galaxy. The clumps also lose mass, especially old stars, by tidal stripping, and the stellar populations contained in the clumps hence remain relatively young (≤200 Myr), as observed. The clumps survive gaseous outflows and stellar loss, because they are wandering in gas-rich turbulent disks from which they can reaccrete gas at high rates compensating for outflows and tidal stripping, overall keeping realistic and self-regulated gaseous and stellar masses. The outflow and accretion rates have specific timescales of a few 10{sup 8} yr, as opposed to rapid and repeated dispersion and reformation of clumps. Our simulations produce gaseous outflows with velocities, densities, and mass loading consistent with observations, and at the same time suggest that the giant clumps survive for hundreds of Myr and complete their migration to the center of high-redshift galaxies. These long-lived clumps are gas-dominated and contain a moderate mass fraction of stars; they drive inside-out disk evolution, thickening, spheroid growth, and fueling of the central

  19. Inversion Build-Up and Cold-Air Outflow in a Small Alpine Sinkhole

    Science.gov (United States)

    Lehner, Manuela; Whiteman, C. David; Dorninger, Manfred

    2017-06-01

    Semi-idealized model simulations are made of the nocturnal cold-air pool development in the approximately 1-km wide and 100-200-m deep Grünloch basin, Austria. The simulations show qualitatively good agreement with vertical temperature and wind profiles and surface measurements collected during a meteorological field expedition. A two-layer stable atmosphere forms in the basin, with a very strong inversion in the lowest part, below the approximate height of the lowest gap in the surrounding orography. The upper part of the stable layer is less strongly stratified and extends to the approximate height of the second-lowest gap. The basin atmosphere cools most strongly during the first few hours of the night, after which temperatures decrease only slowly. An outflow of air forms through the lowest gap in the surrounding orography. The outflow connects with a weak inflow of air through a gap on the opposite sidewall, forming a vertically and horizontally confined jet over the basin. Basin cooling shows strong sensitivity to surface-layer characteristics, highlighting the large impact of variations in vegetation and soil cover on cold-air pool development, as well as the importance of surface-layer parametrization in numerical simulations of cold-air-pool development.

  20. MAGNETIC NESTED-WIND SCENARIOS FOR BIPOLAR OUTFLOWS: PREPLANETARY AND YSO NEBULAR SHAPING

    International Nuclear Information System (INIS)

    Dennis, Timothy J.; Frank, Adam; Blackman, Eric G.; DeMarco, Orsola; Balick, Bruce; Mitran, Sorin

    2009-01-01

    We present results of a series of magnetohydrodynamic (MHD) and hydrodynamic (HD) 2.5 dimensional simulations of the morphology of outflows driven by nested wide-angle winds, i.e., winds that emanate from a central star as well as from an orbiting accretion disk. While our results are broadly relevant to nested-wind systems, we have tuned the parameters of the simulations to touch on issues in both young stellar objects and planetary nebula (PN) studies. In particular, our studies connect to open issues in the early evolution of PNs. We find that nested MHD winds exhibit marked morphological differences from the single MHD wind case along both dimensions of the flow. Nested HD winds, on the other hand, give rise mainly to geometric distortions of an outflow that is topologically similar to the flow arising from a single stellar HD wind. Our MHD results are insensitive to changes in ambient temperature between ionized and un-ionized circumstellar environments. The results are sensitive to the relative mass-loss rates and the relative speeds of the stellar and disk winds. We also present synthetic emission maps of both nested MHD and HD simulations. We find that nested MHD winds show knots of emission appearing on-axis that do not appear in the HD case.

  1. Multi-phase outflows as probes of AGN accretion history

    Science.gov (United States)

    Nardini, Emanuele; Zubovas, Kastytis

    2018-05-01

    Powerful outflows with a broad range of properties (such as velocity, ionization, radial scale and mass loss rate) represent a key feature of active galactic nuclei (AGN), even more so since they have been simultaneously revealed also in individual objects. Here we revisit in a simple analytical framework the recent remarkable cases of two ultraluminous infrared quasars, IRAS F11119+3257 and Mrk 231, which allow us to investigate the physical connection between multi-phase AGN outflows across the ladder of distance from the central supermassive black hole (SMBH). We argue that any major deviations from the standard outflow propagation models might encode unique information on the past SMBH accretion history, and briefly discuss how this could help address some controversial aspects of the current picture of AGN feedback.

  2. The outflow speed of the coma of Halley's comet

    International Nuclear Information System (INIS)

    Combi, M.R.

    1989-01-01

    Data concerning the outflow speed of the coma of Comet Halley are studied in relation to a generalization of the coupled pure-gas-dynamic/Monte Carlo model of Combi and Smyth (1988) to include the dusty-gas dynamics of the inner coma. Measurements made by the Giotto neutral-gas spectrometer, IR water observations from the Kuiper Airborne Observatory, and Doppler radio line profiles of HCN and OH are used to examine the radial dependence of the outflow speed, the asymmetry in the outflow speed, and the overall heliocentric distance dependence of the Doppler profiles, respectively. The results suggest that the model makes it possible to understand the gross long-term behavior and radial structure of the dynamics of the cometary coma. 23 refs

  3. CORONAL MASS EJECTION INDUCED OUTFLOWS OBSERVED WITH HINODE/EIS

    International Nuclear Information System (INIS)

    Jin, M.; Ding, M. D.; Chen, P. F.; Fang, C.; Imada, S.

    2009-01-01

    We investigate the outflows associated with two halo coronal mass ejections (CMEs) that occurred on 2006 December 13 and 14 in NOAA 10930, using the Hinode/EIS observations. Each CME was accompanied by an EIT wave and coronal dimmings. Dopplergrams in the dimming regions are obtained from the spectra of seven EIS lines. The results show that strong outflows are visible in the dimming regions during the CME eruption at different heights from the lower transition region to the corona. It is found that the velocity is positively correlated with the photospheric magnetic field, as well as the magnitude of the dimming. We estimate the mass loss based on height-dependent EUV dimmings and find it to be smaller than the CME mass derived from white-light observations. The mass difference is attributed partly to the uncertain atmospheric model, and partly to the transition region outflows, which refill the coronal dimmings.

  4. Computation of the bounce-average code

    International Nuclear Information System (INIS)

    Cutler, T.A.; Pearlstein, L.D.; Rensink, M.E.

    1977-01-01

    The bounce-average computer code simulates the two-dimensional velocity transport of ions in a mirror machine. The code evaluates and bounce-averages the collision operator and sources along the field line. A self-consistent equilibrium magnetic field is also computed using the long-thin approximation. Optionally included are terms that maintain μ, J invariance as the magnetic field changes in time. The assumptions and analysis that form the foundation of the bounce-average code are described. When references can be cited, the required results are merely stated and explained briefly. A listing of the code is appended

  5. Relative outflow enhancements during major geomagnetic storms – Cluster observations

    Directory of Open Access Journals (Sweden)

    A. Schillings

    2017-12-01

    Full Text Available The rate of ion outflow from the polar ionosphere is known to vary by orders of magnitude, depending on the geomagnetic activity. However, the upper limit of the outflow rate during the largest geomagnetic storms is not well constrained due to poor spatial coverage during storm events. In this paper, we analyse six major geomagnetic storms between 2001 and 2004 using Cluster data. The six major storms fulfil the criteria of Dst  < −100 nT or Kp  > 7+. Since the shape of the magnetospheric regions (plasma mantle, lobe and inner magnetosphere are distorted during large magnetic storms, we use both plasma beta (β and ion characteristics to define a spatial box where the upward O+ flux scaled to an ionospheric reference altitude for the extreme event is observed. The relative enhancement of the scaled outflow in the spatial boxes as compared to the data from the full year when the storm occurred is estimated. Only O+ data were used because H+ may have a solar wind origin. The storm time data for most cases showed up as a clearly distinguishable separate peak in the distribution toward the largest fluxes observed. The relative enhancement in the outflow region during storm time is 1 to 2 orders of magnitude higher compared to less disturbed time. The largest relative scaled outflow enhancement is 83 (7 November 2004 and the highest scaled O+ outflow observed is 2  ×  1014 m−2 s−1 (29 October 2003.

  6. Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

    International Nuclear Information System (INIS)

    Andrews, Brett H.; Weinberg, David H.; Schönrich, Ralph; Johnson, Jennifer A.

    2017-01-01

    Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatment of inflow, outflow, star formation efficiency (SFE), the stellar initial mass function, the SN Ia delay time distribution, stellar yields, and stellar population mixing. Using flexCE, a flexible one-zone chemical evolution code, we investigate the effects of and trade-offs between parameters. Two critical parameters are SFE and the outflow mass-loading parameter, which shift the knee in [O/Fe]–[Fe/H] and the equilibrium abundances that the simulations asymptotically approach, respectively. One-zone models with simple star formation histories follow narrow tracks in [O/Fe]–[Fe/H] unlike the observed bimodality (separate high- α and low- α sequences) in this plane. A mix of one-zone models with inflow timescale and outflow mass-loading parameter variations, motivated by the inside-out galaxy formation scenario with radial mixing, reproduces the two sequences better than a one-zone model with two infall epochs. We present [X/Fe]–[Fe/H] tracks for 20 elements assuming three different supernova yield models and find some significant discrepancies with solar neighborhood observations, especially for elements with strongly metallicity-dependent yields. We apply principal component abundance analysis to the simulations and existing data to reveal the main correlations among abundances and quantify their contributions to variation in abundance space. For the stellar population mixing scenario, the abundances of α -elements and elements with metallicity-dependent yields dominate the first and second principal components, respectively, and collectively explain 99% of the variance in the model. flexCE is a python package available at https://github.com/bretthandrews/flexCE.

  7. Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Brett H. [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Weinberg, David H.; Schönrich, Ralph; Johnson, Jennifer A., E-mail: andrewsb@pitt.edu [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

    2017-02-01

    Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatment of inflow, outflow, star formation efficiency (SFE), the stellar initial mass function, the SN Ia delay time distribution, stellar yields, and stellar population mixing. Using flexCE, a flexible one-zone chemical evolution code, we investigate the effects of and trade-offs between parameters. Two critical parameters are SFE and the outflow mass-loading parameter, which shift the knee in [O/Fe]–[Fe/H] and the equilibrium abundances that the simulations asymptotically approach, respectively. One-zone models with simple star formation histories follow narrow tracks in [O/Fe]–[Fe/H] unlike the observed bimodality (separate high- α and low- α sequences) in this plane. A mix of one-zone models with inflow timescale and outflow mass-loading parameter variations, motivated by the inside-out galaxy formation scenario with radial mixing, reproduces the two sequences better than a one-zone model with two infall epochs. We present [X/Fe]–[Fe/H] tracks for 20 elements assuming three different supernova yield models and find some significant discrepancies with solar neighborhood observations, especially for elements with strongly metallicity-dependent yields. We apply principal component abundance analysis to the simulations and existing data to reveal the main correlations among abundances and quantify their contributions to variation in abundance space. For the stellar population mixing scenario, the abundances of α -elements and elements with metallicity-dependent yields dominate the first and second principal components, respectively, and collectively explain 99% of the variance in the model. flexCE is a python package available at https://github.com/bretthandrews/flexCE.

  8. Simulations

    CERN Document Server

    Ngada, Narcisse

    2015-06-15

    The complexity and cost of building and running high-power electrical systems make the use of simulations unavoidable. The simulations available today provide great understanding about how systems really operate. This paper helps the reader to gain an insight into simulation in the field of power converters for particle accelerators. Starting with the definition and basic principles of simulation, two simulation types, as well as their leading tools, are presented: analog and numerical simulations. Some practical applications of each simulation type are also considered. The final conclusion then summarizes the main important items to keep in mind before opting for a simulation tool or before performing a simulation.

  9. Does the X-ray outflow quasar PDS 456 have a UV outflow at 0.3c?

    Science.gov (United States)

    Hamann, Fred; Chartas, George; Reeves, James; Nardini, Emanuele

    2018-05-01

    The quasar PDS 456 (at redshift ˜0.184) has a prototype ultra-fast outflow (UFO) measured in X-rays. This outflow is highly ionized with relativistic speeds, large total column densities log NH(cm-2) > 23, and large kinetic energies that could be important for feedback to the host galaxy. A UV spectrum of PDS 456 obtained with the Hubble Space Telescope in 2000 contains one well-measured broad absorption line (BAL) at ˜1346 Å (observed) that might be Ly α at v ≈ 0.06c or N V λ1240 at v ≈ 0.08c. However, we use photoionization models and comparisons to other outflow quasars to show that these BAL identifications are problematic because other lines that should accompany them are not detected. We argue that the UV BAL is probably C IV at v ≈ 0.30c. This would be the fastest UV outflow ever reported, but its speed is similar to the X-ray outflow and its appearance overall is similar to relativistic UV BALs observed in other quasars. The C IV BAL identification is also supported indirectly by the tentative detection of another broad C IV line at v ≈ 0.19c. The high speeds suggest that the UV outflow originates with the X-ray UFO crudely 20-30 rg from the central black hole. We speculate that the C IV BAL might form in dense clumps embedded in the X-ray UFO, requiring density enhancements of only ≳0.4 dex compared to clumpy structures already inferred for the soft X-ray absorber in PDS 456. The C IV BAL might therefore be the first detection of low-ionization clumps proposed previously to boost the opacities in UFOs for radiative driving.

  10. Average beta-beating from random errors

    CERN Document Server

    Tomas Garcia, Rogelio; Langner, Andy Sven; Malina, Lukas; Franchi, Andrea; CERN. Geneva. ATS Department

    2018-01-01

    The impact of random errors on average β-beating is studied via analytical derivations and simulations. A systematic positive β-beating is expected from random errors quadratic with the sources or, equivalently, with the rms β-beating. However, random errors do not have a systematic effect on the tune.

  11. Effects of surface-water and groundwater inflows and outflows on the hydrology of the Tsala Apopka Lake Basin in Citrus County, Florida

    Science.gov (United States)

    Sepúlveda, Nicasio; Fulkerson, Mark; Basso, Ron; Ryan, Patrick J.

    2018-05-21

    The U.S. Geological Survey, in cooperation with the Southwest Florida Water Management District, initiated a study to quantify the inflows and outflows in the Floral City, Inverness, and Hernando pools of the Tsala Apopka Lake Basin in Citrus County, Florida. This study assesses hydrologic changes in pool stages, groundwater levels, spring flows, and streamflows caused by the diversion of streamflow from the Withlacoochee River to the Tsala Apopka Lake Basin through water-control structures. A surface-water/groundwater flow model was developed using hydraulic parameters for lakes, streams, the unsaturated zone, and the underlying surficial and Upper Floridan aquifers estimated using an inverse modeling calibration technique. After calibration, the model was used to assess the relation between inflows and outflows in the Tsala Apopka Lake Basin and changes in pool stages.Simulation results using the calibrated surface-water/groundwater flow model showed that leakage rates from the pools to the Upper Floridan aquifer were largest at the deep lake cells and that these leakage rates to the Upper Floridan aquifer were the highest in the model area. Downward leakage to the Upper Floridan aquifer occurred beneath most of the extent of the Floral City, Inverness, and Hernando pools. These leakage rates depended on the lakebed leakance and the difference between lake stages and heads in the Upper Floridan aquifer. Leakage rates were higher for the Floral City pool than for the Inverness pool, and higher for the Inverness pool than for the Hernando pool. Lakebed leakance was higher for the Floral City pool than for the Hernando pool, and higher for the Hernando pool than for the Inverness pool.Simulation results showed that the average recharge rate to the surficial aquifer was 10.3 inches per year for the 2004 to 2012 simulation period. Areas that recharge the surficial aquifer covered about 86 percent of the model area. Simulations identified areas along segments of the

  12. A submillimeter galaxy illuminating its circumgalactic medium: Lyα scattering in a cold, clumpy outflow

    Energy Technology Data Exchange (ETDEWEB)

    Geach, J. E.; Coppin, K. E. K.; Smith, D. J. B. [Center for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Bower, R. G.; Alexander, D. M.; Swinbank, A. M. [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Blain, A. W. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Bremer, M. N. [School of Physics, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Chapin, E. L. [XMM SOC, ESAC, Apartado 78, E-28691 Villanueva de la Canada, Madrid (Spain); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University Halifax, NS B3H 3J5 (Canada); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Dunlop, J. S.; Koprowski, M. P.; Michałowski, M. J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Farrah, D. [Virginia Polytechnic Institute and State University Department of Physics, MC 0435, 910 Drillfield Drive, Blacksburg, VA 24061 (United States); Jenness, T. [Joint Astronomy Centre, 660 North A' ohoku Place University Park, Hilo, HI 96720 (United States); Robson, E. I. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Scott, D. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Spaans, M. [Kapteyn Institute, University of Groningen, PO Box 800, 9700 AV Groningen (Netherlands); Van der Werf, P., E-mail: j.geach@herts.ac.uk [Leiden Observatory, Leiden University, PO box 9513, 2300 RA Leiden (Netherlands)

    2014-09-20

    We report the detection at 850 μm of the central source in SSA22-LAB1, the archetypal 'Lyman-α Blob' (LAB), a 100 kpc scale radio-quiet emission-line nebula at z = 3.1. The flux density of the source, S {sub 850} = 4.6 ± 1.1 mJy, implies the presence of a galaxy or group of galaxies with a total luminosity of L {sub IR} ≈ 10{sup 12} L {sub ☉}. The position of an active source at the center of a ∼50 kpc radius ring of linearly polarized Lyα emission detected by Hayes et al. suggests that the central source is leaking Lyα photons preferentially in the plane of the sky, which undergo scattering in H I clouds at a large galactocentric radius. The Lyα morphology around the submillimeter detection is reminiscent of a biconical outflow, and the average Lyα line profiles of the two 'lobes' are dominated by a red peak, which is expected for a resonant line emerging from a medium with a bulk velocity gradient that is outflowing relative to the line center. Taken together, these observations provide compelling evidence that the central active galaxy (or galaxies) is responsible for a large fraction of the extended Lyα emission and morphology. Less clear is the history of the cold gas in the circumgalactic medium being traced by Lyα: is it mainly pristine material accreting into the halo that has not yet been processed through an interstellar medium (ISM), now being blown back as it encounters an outflow, or does it mainly comprise gas that has been swept-up within the ISM and expelled from the galaxy?.

  13. Quasar Feedback in the Ultraluminous Infrared Galaxy F11119+3257: Connecting the Accretion Disk Wind with the Large-scale Molecular Outflow

    Science.gov (United States)

    Veilleux, S.; Bolatto, A.; Tombesi, F.; Meléndez, M.; Sturm, E.; González-Alfonso, E.; Fischer, J.; Rupke, D. S. N.

    2017-07-01

    In Tombesi et al., we reported the first direct evidence for a quasar accretion disk wind driving a massive (>100 M ⊙ yr-1) molecular outflow. The target was F11119+3257, an ultraluminous infrared galaxy (ULIRG) with unambiguous type 1 quasar optical broad emission lines. The energetics of the accretion disk wind and molecular outflow were found to be consistent with the predictions of quasar feedback models where the molecular outflow is driven by a hot energy-conserving bubble inflated by the inner quasar accretion disk wind. However, this conclusion was uncertain because the mass outflow rate, momentum flux, and mechanical power of the outflowing molecular gas were estimated from the optically thick OH 119 μm transition profile observed with Herschel. Here, we independently confirm the presence of the molecular outflow in F11119+3257, based on the detection of ˜±1000 km s-1 blue- and redshifted wings in the CO(1-0) emission line profile derived from deep ALMA observations obtained in the compact array configuration (˜2.″8 resolution). The broad CO(1-0) line emission appears to be spatially extended on a scale of at least ˜7 kpc from the center. Mass outflow rate, momentum flux, and mechanical power of (80-200) {R}7-1 M ⊙ yr-1, (1.5-3.0) {R}7-1 L AGN/c, and (0.15-0.40)% {R}7-1 {L}{AGN}, respectively, are inferred from these data, assuming a CO-to-H2 conversion factor appropriate for a ULIRG (R 7 is the radius of the outflow normalized to 7 kpc, and L AGN is the AGN luminosity). These rates are time-averaged over a flow timescale of 7 × 106 yr. They are similar to the OH-based rates time-averaged over a flow timescale of 4 × 105 yr, but about a factor of 4 smaller than the local (“instantaneous” ≲105 yr) OH-based estimates cited in Tombesi et al. The implications of these new results are discussed in the context of time-variable quasar-mode feedback and galaxy evolution. The need for an energy-conserving bubble to explain the molecular outflow

  14. Misalignment of magnetic fields and outflows in protostellar cores

    NARCIS (Netherlands)

    Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erica; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.; Looney, Leslie W.; Matthews, Brenda C.; Mundy, Lee; Pillai, Thushara; Pound, Marc W.; Stephens, Ian W.; Tobin, John J.; Vaillancourt, John E.; Volgenau, N. H.; Wright, Melvyn C. H.

    2013-01-01

    We present results of lambda 1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with similar to 2 ''.5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of similar to 1000 AU are not tightly aligned with outflows from the

  15. Cardiac outflow tract malformations in chick embryos exposed to homocysteine

    NARCIS (Netherlands)

    M.J. Boot (Marit); R.P.M. Steegers-Theunissen (Régine); R.E. Poelmann (Robert); L. van Iperen (Liesbeth); A.C. Gittenberger-De Groot (Adriana)

    2004-01-01

    textabstractIncreased homocysteine concentrations have been associated with cardiac outflow tract defects. It has been hypothesized that cardiac neural crest cells were the target cells in these malformations. Cardiac neural crest cells migrate from the neural tube and contribute to the condensed

  16. Standing Shocks around Black Holes and Estimation of Outflow ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. We self-consistently obtain shock locations in an accretion flow by using an analytical method. One can obtain the spectral properties, quasi-periodic oscillation frequencies and the outflow rates when the inflow parameters are known. Since temperature of the CENBOL decides the spectral states of the black hole, ...

  17. PROTOSTELLAR OUTFLOW HEATING IN A GROWING MASSIVE PROTOCLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ke; Wu Yuefang; Zhang Huawei [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Zhang Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Li Huabai, E-mail: kwang@cfa.harvard.edu [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2012-02-15

    The dense molecular clump P1 in the infrared dark cloud complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here, we present the Expanded Very Large Array spectral line observations toward P1 in the NH{sub 3} (J,K) = (1,1), (2,2), (3,3) lines, as well as H{sub 2}O and class I CH{sub 3}OH masers. Multiple NH{sub 3} transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH{sub 3} (3,3) emission features are also found coincident with the outflows. A weak NH{sub 3} (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may not be effective in suppressing fragmentation during the formation of massive cores.

  18. PROTOSTELLAR OUTFLOW HEATING IN A GROWING MASSIVE PROTOCLUSTER

    International Nuclear Information System (INIS)

    Wang Ke; Wu Yuefang; Zhang Huawei; Zhang Qizhou; Li Huabai

    2012-01-01

    The dense molecular clump P1 in the infrared dark cloud complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here, we present the Expanded Very Large Array spectral line observations toward P1 in the NH 3 (J,K) = (1,1), (2,2), (3,3) lines, as well as H 2 O and class I CH 3 OH masers. Multiple NH 3 transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH 3 (3,3) emission features are also found coincident with the outflows. A weak NH 3 (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may not be effective in suppressing fragmentation during the formation of massive cores.

  19. Quenching of Star Formation in Molecular Outflow Host NGC 1266

    NARCIS (Netherlands)

    Alatalo, K.; Nyland, K. E.; Graves, G.; Deustua, S.; Young, L. M.; Davis, T. A.; Crocker, A. F.; Bureau, M.; Bayet, E.; Blitz, L.; Bois, M.; Bournaud, F.; Cappellari, M.; Davies, R. L.; de Zeeuw, P. T.; Emsellem, E.; Khochfar, S.; Krajnovic, D.; Kuntschner, H.; McDermid, R. M.; Morganti, R.; Naab, T.; Oosterloo, T.; Sarzi, M.; Scott, N.; Serra, P.; Weijmans, A.; Wong, Tony; Ott, Jürgen

    We detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS3D survey (Cappellari et al. 2011) and how it plays host to an AGN-driven molecular outflow, potentially quenching all of its star formation (SF) within the next 100 Myr. While major mergers appear to play a

  20. Reconstructing Global-scale Ionospheric Outflow With a Satellite Constellation

    Science.gov (United States)

    Liemohn, M. W.; Welling, D. T.; Jahn, J. M.; Valek, P. W.; Elliott, H. A.; Ilie, R.; Khazanov, G. V.; Glocer, A.; Ganushkina, N. Y.; Zou, S.

    2017-12-01

    The question of how many satellites it would take to accurately map the spatial distribution of ionospheric outflow is addressed in this study. Given an outflow spatial map, this image is then reconstructed from a limited number virtual satellite pass extractions from the original values. An assessment is conducted of the goodness of fit as a function of number of satellites in the reconstruction, placement of the satellite trajectories relative to the polar cap and auroral oval, season and universal time (i.e., dipole tilt relative to the Sun), geomagnetic activity level, and interpolation technique. It is found that the accuracy of the reconstructions increases sharply from one to a few satellites, but then improves only marginally with additional spacecraft beyond 4. Increased dwell time of the satellite trajectories in the auroral zone improves the reconstruction, therefore a high-but-not-exactly-polar orbit is most effective for this task. Local time coverage is also an important factor, shifting the auroral zone to different locations relative to the virtual satellite orbit paths. The expansion and contraction of the polar cap and auroral zone with geomagnetic activity influences the coverage of the key outflow regions, with different optimal orbit configurations for each level of activity. Finally, it is found that reconstructing each magnetic latitude band individually produces a better fit to the original image than 2-D image reconstruction method (e.g., triangulation). A high-latitude, high-altitude constellation mission concept is presented that achieves acceptably accurate outflow reconstructions.

  1. Efficient cold outflows driven by cosmic rays in high-redshift galaxies and their global effects on the IGM

    Science.gov (United States)

    Samui, Saumyadip; Subramanian, Kandaswamy; Srianand, Raghunathan

    2018-05-01

    We present semi-analytical models of galactic outflows in high-redshift galaxies driven by both hot thermal gas and non-thermal cosmic rays. Thermal pressure alone may not sustain a large-scale outflow in low-mass galaxies (i.e. M ˜ 108 M⊙), in the presence of supernovae feedback with large mass loading. We show that inclusion of cosmic ray pressure allows outflow solutions even in these galaxies. In massive galaxies for the same energy efficiency, cosmic ray-driven winds can propagate to larger distances compared to pure thermally driven winds. On an average gas in the cosmic ray-driven winds has a lower temperature which could aid detecting it through absorption lines in the spectra of background sources. Using our constrained semi-analytical models of galaxy formation (that explains the observed ultraviolet luminosity functions of galaxies), we study the influence of cosmic ray-driven winds on the properties of the intergalactic medium (IGM) at different redshifts. In particular, we study the volume filling factor, average metallicity, cosmic ray and magnetic field energy densities for models invoking atomic cooled and molecular cooled haloes. We show that the cosmic rays in the IGM could have enough energy that can be transferred to the thermal gas in presence of magnetic fields to influence the thermal history of the IGM. The significant volume filling and resulting strength of IGM magnetic fields can also account for recent γ-ray observations of blazars.

  2. Improving consensus structure by eliminating averaging artifacts

    Directory of Open Access Journals (Sweden)

    KC Dukka B

    2009-03-01

    Full Text Available Abstract Background Common structural biology methods (i.e., NMR and molecular dynamics often produce ensembles of molecular structures. Consequently, averaging of 3D coordinates of molecular structures (proteins and RNA is a frequent approach to obtain a consensus structure that is representative of the ensemble. However, when the structures are averaged, artifacts can result in unrealistic local geometries, including unphysical bond lengths and angles. Results Herein, we describe a method to derive representative structures while limiting the number of artifacts. Our approach is based on a Monte Carlo simulation technique that drives a starting structure (an extended or a 'close-by' structure towards the 'averaged structure' using a harmonic pseudo energy function. To assess the performance of the algorithm, we applied our approach to Cα models of 1364 proteins generated by the TASSER structure prediction algorithm. The average RMSD of the refined model from the native structure for the set becomes worse by a mere 0.08 Å compared to the average RMSD of the averaged structures from the native structure (3.28 Å for refined structures and 3.36 A for the averaged structures. However, the percentage of atoms involved in clashes is greatly reduced (from 63% to 1%; in fact, the majority of the refined proteins had zero clashes. Moreover, a small number (38 of refined structures resulted in lower RMSD to the native protein versus the averaged structure. Finally, compared to PULCHRA 1, our approach produces representative structure of similar RMSD quality, but with much fewer clashes. Conclusion The benchmarking results demonstrate that our approach for removing averaging artifacts can be very beneficial for the structural biology community. Furthermore, the same approach can be applied to almost any problem where averaging of 3D coordinates is performed. Namely, structure averaging is also commonly performed in RNA secondary prediction 2, which

  3. The difference between alternative averages

    Directory of Open Access Journals (Sweden)

    James Vaupel

    2012-09-01

    Full Text Available BACKGROUND Demographers have long been interested in how compositional change, e.g., change in age structure, affects population averages. OBJECTIVE We want to deepen understanding of how compositional change affects population averages. RESULTS The difference between two averages of a variable, calculated using alternative weighting functions, equals the covariance between the variable and the ratio of the weighting functions, divided by the average of the ratio. We compare weighted and unweighted averages and also provide examples of use of the relationship in analyses of fertility and mortality. COMMENTS Other uses of covariances in formal demography are worth exploring.

  4. Ionized and Neutral Outflows in the QUEST QSOs

    Science.gov (United States)

    Veilleux, Sylvain

    2011-10-01

    The role of galactic winds in gas-rich mergers is of crucial importance to understand galaxy and SMBH evolution. In recent months, our group has had three major scientific breakthroughs in this area: {1} The discovery with Herschel of massive molecular {OH-absorbing} outflows in several ULIRGs, including the nearest quasar, Mrk 231. {2} The independent discovery from mm-wave interferometric observations in the same object of a spatially resolved molecular {CO-emitting} wind with estimated mass outflow rate 3x larger than the star formation rate and spatially coincident with blueshifted neutral {Na ID-absorbing} gas in optical long-slit spectra. {3} The unambiguous determination from recent Gemini/IFU observations that the Na ID outflow in this object is wide-angle, thus driven by a QSO wind rather than a jet. This powerful outflow may be the long-sought "smoking gun" of quasar mechanical feedback purported to transform gas-rich mergers. However, our Herschel survey excludes all FIR-faint {UV-bright} "classic" QSOs by necessity. So here we propose a complementary FUV absorption-line survey of all FIR-bright -and- FIR-faint QSOs from the same parent sample. New {19 targets} and archival {11} spectra will be used to study, for the first time, the gaseous environments of QSOs as a function of host properties and age across the merger sequence ULIRG -> QSO. These data will allow us to distinguish between ionized & neutral quasar-driven outflows, starburst-driven winds, and tidal debris around the mergers. They will also be uniquely suited for a shallow but broad study of the warm & warm-hot intergalactic media, complementary to on-going surveys that are deeper but narrower.

  5. Atmospheric outflow of nutrients to the Bay of Bengal: Impact of anthropogenic sources..

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, B.; Sarin, M.M.; Sarma, V.V.S.S.

    outflow show pronounced temporal variability. The inorganic nitrogen (NH4 + -N: ~90% of NInorg) dominates the total soluble nitrogen (NTot). Although the contribution of organic nitrogen is not significant, the mass ratio of NOrg/NTotin the outflow varied...

  6. Human cerebral venous outflow pathway depends on posture and central venous pressure

    Science.gov (United States)

    Gisolf, J; van Lieshout, J J; van Heusden, K; Pott, F; Stok, W J; Karemaker, J M

    2004-01-01

    Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R2 = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins. PMID:15284348

  7. A young bipolar outflow from IRAS 15398-3359

    Science.gov (United States)

    Bjerkeli, P.; Jørgensen, J. K.; Brinch, C.

    2016-03-01

    Context. Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry as well as the kinematical information, allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. Aims: We aim to determine the spatial distribution of different species that are of different chemical origin. This is to examine the physical processes in play in the observed region. From the kinematical information of the emission lines we aim to determine the nature of the infalling and outflowing gas in the system. We also aim to determine the physical properties of the outflow. Methods: Maps from the Submillimeter Array (SMA) reveal the spatial distribution of the gaseous emission towards IRAS 15398-3359. The line radiative transfer code LIME is used to construct a full 3D model of the system taking all relevant components and scales into account. Results: CO, HCO+, and N2H+ are detected and shown to trace the motions of the outflow. For CO, the circumstellar envelope and the surrounding cloud also have a profound impact on the observed line profiles. N2H+ is detected in the outflow, but is suppressed towards the central region, perhaps because of the competing reaction between CO and H3+ in the densest regions as well as the destruction of N2H+ by CO. N2D+ is detected in a ridge south-west of the protostellar condensation and is not associated with the outflow. The morphology and kinematics of the CO emission suggests that the source is younger than ~1000 years. The mass, momentum, momentum rate, mechanical luminosity, kinetic energy, and mass-loss rate are also all estimated to be low. A full 3D radiative transfer model of the system can explain all the kinematical and morphological features in the system.

  8. The Gaseous Environments of Quasars: Outflows, Feedback & Cold Mode Accretion

    Science.gov (United States)

    Chen, Chen; Hamann, Fred

    2018-06-01

    The early stages of massive galaxy evolution can involve galaxy-scale outflows driven by a starburst or a central quasar and cold-mode accretion (infall) that adds to the mass buildup in the galaxies. I will describe three related studies that use quasar absorption lines to measure outflows, infall, and the general gaseous environments of quasars across a range of spatial scales. The three studies are: 1) High-resolution spectroscopy with Keck-HIRES and VLT-UVES to study associated absorption lines (AALs) that have redshifts greater than the emission redshifts indicating infall and/or rich multi-component AAL complexes that might be interstellar clouds in the host galaxies that have been shredded and dispersed by a fast unseen quasar-driven wind. The data provide strong constraints on the gas kinematics, spatial structure, column densities, metallicities, and energetics. 2) A complete inventory of high-velocity CIV 1548,1550 mini-BAL outflows in quasars using high-resolution high signal-to-noise spectra in the public VLT-UVES and Keck-HIRES archives. This sensitive mini-BAL survey fills an important niche between previous work on narrow absorption lines (NALs) and the much-studied broad absorption lines (BALs) to build a more complete picture of quasar outflows. I will report of the mini-BAL statistics, the diversity of lines detected, and some tests for correlations with the quasar properties. We find, for example, that mini-BALs at v > 4000 km/s in at least 10% of 511 quasars studied, including 1% at v > 0.1 c. Finally, 3) Use the much larger database of NALs measured in 262,449 BOSS quasars by York et al. (in prep.) to study their potential relationships to the quasars and, specifically, their origins in quasar outflows. This involves primarily comparisons of the incidence and properties of NALs at different velocity shifts to other measured properties of the quasars such as BAL outflows, emission line characteristics, radio-loudness, and red colors. We find

  9. Character and dynamics of the Red Sea and Persian Gulf outflows

    Science.gov (United States)

    Bower, Amy S.; Hunt, Heather D.; Price, James F.

    2000-03-01

    Historical hydrographic data and a numerical plume model are used to investigate the initial transformation, dynamics, and spreading pathways of Red Sea and Persian Gulf outflow waters where they enter the Indian Ocean. The annual mean transport of these outflows is relatively small (outflows in that they flow over very shallow sills (depth Red Sea outflow exhibits strong seasonal variability in transport. The four main results of this study are as follows. First, on the basis of observed temperature-salinity (T-S) characteristics of the outflow source and product waters we estimate that the Red Sea and Persian Gulf outflows are diluted by factors of ˜2.5 and 4, respectively, as they descend from sill depth to their depth of neutral buoyancy. The high-dilution factor for the Persian Gulf outflow results from the combined effects of large initial density difference between the outflow source water and oceanic water and low outflow transport. Second, the combination of low latitude and low outflow transport (and associated low outflow thickness) results in Ekman numbers for both outflows that are O(1). This indicates that they should be thought of as frictional density currents modified by rotation rather than geostrophic density currents modified by friction. Third, different mixing histories along the two channels that direct Red Sea outflow water into the open ocean result in product waters with significantly different densities, which probably contributes to the multilayered structure of the Red Sea product waters. In both outflows, seasonal variations in source water and oceanic properties have some effect on the T-S of the product waters, but they have only a minor impact on equilibrium depth. Fourth, product waters from both outflows are advected away from the sill region in narrow boundary currents, at least during part of the year. At other times, the product water appears more in isolated patches.

  10. A young bipolar outflow from IRAS 15398-3359

    DEFF Research Database (Denmark)

    Bjerkeli, Per; Jørgensen, Jes Kristian; Brinch, Christian

    2016-01-01

    emission towards IRAS 15398-3359. The lineradiative transfer code LIME is used to construct a full 3D model of thesystem taking all relevant components and scales into account. Results: CO, HCO+, and N2H+ aredetected and shown to trace the motions of the outflow. For CO, thecircumstellar envelope...... and the surrounding cloud also have a profoundimpact on the observed line profiles. N2H+ isdetected in the outflow, but is suppressed towards the central region,perhaps because of the competing reaction between CO andH3+ in the densest regions as well as thedestruction of N2H+ by CO.N2D+ is detected in a ridge south...

  11. FOREIGN DIRECT INVESTMENT OUTFLOWS FROM CHINA AND INDIA

    OpenAIRE

    K. C. FUNG; ALICIA GARCIA-HERRERO

    2012-01-01

    In this paper, we examine the determinants of Indian and Chinese FDI outflows. There are three sets of results. First, Chinese investment is attracted to more corrupt countries, while India is attracted to economies with better rule of law. Further analysis suggests that our result of China investing in more corrupt destinations is mostly driven by Chinese investment in the sub-sample of African countries. While we do not conduct economic welfare analysis, several studies in the literature re...

  12. Effects of Energetic Ion Outflow on Magnetospheric Dynamics

    Science.gov (United States)

    Kistler, L. M.; Mouikis, C.; Lund, E. J.; Menz, A.; Nowrouzi, N.

    2016-12-01

    There are two dominant regions of energetic ion outflow: the nightside auroral region and the dayside cusp. Processes in these regions can accelerate ions up to keV energies. Outflow from the nightside has direct access to the plasma sheet, while outflow from the cusp is convected over the polar cap and into the lobes. The cusp population can enter the plasma sheet from the lobe, with higher energy ions entering further down the tail than lower energy ions. During storm times, the O+ enhanced plasma sheet population is convected into the inner magnetosphere. The plasma that does not get trapped in the inner magnetosphere convects to the magnetopause where reconnection is taking place. An enhanced O+ population can change the plasma mass density, which may have the effect of decreasing the reconnection rate. In addition O+ has a larger gyroradius than H+ at the same velocity or energy. Because of this, there are larger regions where the O+ is demagnetized, which can lead to larger acceleration because the O+ can move farther in the direction of the electric field. In this talk we will review results from Cluster, Van Allen Probes, and MMS, on how outflow from the two locations affects magnetospheric dynamics. We will discuss whether enhanced O+ from either population has an effect on the reconnection rate in the tail or at the magnetopause. We will discuss how the two populations impact the inner magnetosphere during storm times. And finally, we will discuss whether either population plays a role in triggering substorms, particularly during sawtooth events.

  13. MULTIPLE OUTFLOWS IN THE GIANT ERUPTION OF A MASSIVE STAR

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, Roberta M.; Gordon, Michael S.; Jones, Terry J. [Minnesota Institute for Astrophysics, 116 Church St. SE, University of Minnesota, Minneapolis, MN 55455 (United States); Martin, John C., E-mail: roberta@umn.edu [University of Illinois Springfield, Springfield, IL 62703 (United States)

    2016-08-01

    The supernova impostor PSN J09132750+7627410 in NGC 2748 reached a maximum luminosity of ≈−14 mag. It was quickly realized that it was not a true supernova, but another example of a nonterminal giant eruption. PSN J09132750+7627410 is distinguished by multiple P Cygni absorption minima in the Balmer emission lines that correspond to outflow velocities of −400, −1100, and −1600 km s{sup −1}. Multiple outflows have been observed in only a few other objects. In this paper we describe the evolution of the spectrum and the P Cygni profiles for 3 months past maximum, the post-maximum formation of a cool, dense wind, and the identification of a possible progenitor. One of the possible progenitors is an infrared source. Its pre-eruption spectral energy distribution suggests a bolometric luminosity of −8.3 mag and a dust temperature of 780 K. If it is the progenitor, it is above the AGB limit, unlike the intermediate-luminosity red transients. The three P Cygni profiles could be due to ejecta from the current eruption, the wind of the progenitor, or previous mass-loss events. We suggest that they were all formed as part of the same high-mass-loss event and are due to material ejected at different velocities or energies. We also suggest that multiple outflows during giant eruptions may be more common than reported.

  14. CLUSTERED STAR FORMATION AND OUTFLOWS IN AFGL 2591

    International Nuclear Information System (INIS)

    Sanna, A.; Carrasco-González, C.; Menten, K. M.; Brunthaler, A.; Reid, M. J.; Moscadelli, L.; Rygl, K. L. J.

    2012-01-01

    We report on a detailed study of the water maser kinematics and radio continuum emission toward the most massive and young object in the star-forming region AFGL 2591. Our analysis shows at least two spatial scales of multiple star formation, one projected across 0.1 pc on the sky and another one at about 2000 AU from a ZAMS star of about 38 M ☉ . This young stellar object drives a powerful jet- and wind-driven outflow system with the water masers associated to the outflow walls, previously detected as a limb-brightened cavity in the NIR band. At about 1300 AU to the north of this object a younger protostar drives two bow shocks, outlined by arc-like water maser emission, at 200 AU either side of the source. We have traced the velocity profile of the gas that expands along these arc-like maser structures and compared it with the jet-driven outflow model. This analysis suggests that the ambient medium around the northern protostar is swept up by a jet-driven shock (>66 km s –1 ) and perhaps a lower-velocity (∼10 km s –1 ) wind with an opening angle of about 20° from the jet axis.

  15. CLUSTERED STAR FORMATION AND OUTFLOWS IN AFGL 2591

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, A.; Carrasco-Gonzalez, C.; Menten, K. M.; Brunthaler, A. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Reid, M. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Moscadelli, L. [INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze (Italy); Rygl, K. L. J., E-mail: asanna@mpifr-bonn.mpg.de [IFSI-INAF, Istituto di Fisica dello Spazio Interplanetario, Via del Fosso del Cavaliere 100, 00133 Roma (Italy)

    2012-02-01

    We report on a detailed study of the water maser kinematics and radio continuum emission toward the most massive and young object in the star-forming region AFGL 2591. Our analysis shows at least two spatial scales of multiple star formation, one projected across 0.1 pc on the sky and another one at about 2000 AU from a ZAMS star of about 38 M{sub Sun }. This young stellar object drives a powerful jet- and wind-driven outflow system with the water masers associated to the outflow walls, previously detected as a limb-brightened cavity in the NIR band. At about 1300 AU to the north of this object a younger protostar drives two bow shocks, outlined by arc-like water maser emission, at 200 AU either side of the source. We have traced the velocity profile of the gas that expands along these arc-like maser structures and compared it with the jet-driven outflow model. This analysis suggests that the ambient medium around the northern protostar is swept up by a jet-driven shock (>66 km s{sup -1}) and perhaps a lower-velocity ({approx}10 km s{sup -1}) wind with an opening angle of about 20 Degree-Sign from the jet axis.

  16. VY Canis Majoris: Observational Studies of the Outflow

    Science.gov (United States)

    Harwit, M.

    2001-12-01

    A number of recent studies carried out with the Infrared Space Observatory, ISO, and the Submillimeter Wave Astronomy Satellite, SWAS, provide new information on the chemical composition of the dust and the geometry of the outflow. With ISO, we have obtained a near-, mid-, and far-infrared spectrum of VY CMa that shows the strong preponderance of amorphous, as contrasted to crystalline, silicates. The sharp spectral slope in the near-infrared suggests the presence also of iron grains. While an excellent theoretical fit to the data is obtained, we emphasize that this is far from unique. A resolution of ambiguities will require a self-consistent model that considers not only radiative transfer, but also plausible elemental abundances, laboratory studies of chemical condensation sequences, and gas dynamics. With SWAS we have obtained a high-resolution spectrum of the 557GHz ground state transition of ortho-water. The spectral profile enables us to rule out a number of outflow geometries proposed in the literature. With ISO we also obtained the intensities and velocity structure of several other spectral lines of water. Most of these lines must be optically thick but effectively thin, a circumstance that permits us to make use of recent gas-dynamic models to locate the radial position in the outflow where individual lines are emitted.

  17. Large sea ice outflow into the Nares Strait in 2007

    DEFF Research Database (Denmark)

    Kwok, R.; Pedersen, L.T.; Gudmandsen, Preben

    2010-01-01

    Sea ice flux through the Nares Strait is most active during the fall and early winter, ceases in mid- to late winter after the formation of ice arches along the strait, and re-commences after breakup in summer. In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea...... at Fram Strait. Clearly, the ice arches control Arctic sea ice outflow. The duration of unobstructed flow explains more than 84% of the variance in the annual area flux. In our record, seasonal stoppages are always associated with the formation of an arch near the same location in the southern Kane Basin...... ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 x 10(3) km(2) and 254 km(3) are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents similar to 10% of our estimates of the mean ice export...

  18. Ultrafast outflows disappear in high-radiation fields

    Science.gov (United States)

    Pinto, C.; Alston, W.; Parker, M. L.; Fabian, A. C.; Gallo, L. C.; Buisson, D. J. K.; Walton, D. J.; Kara, E.; Jiang, J.; Lohfink, A.; Reynolds, C. S.

    2018-05-01

    Ultrafast outflows (UFOs) are the most extreme winds launched by active galactic nuclei (AGN) due to their mildly relativistic speeds (˜0.1-0.3c) and are thought to significantly contribute to galactic evolution via AGN feedback. Their nature and launching mechanism are however not well understood. Recently, we have discovered the presence of a variable UFO in the narrow-line Seyfert 1 IRAS 13224-3809. The UFO varies in response to the brightness of the source. In this work we perform flux-resolved X-ray spectroscopy to study the variability of the UFO and found that the ionization parameter is correlated with the luminosity. In the brightest states the gas is almost completely ionized by the powerful radiation field and the UFO is hardly detected. This agrees with our recent results obtained with principal component analysis. We might have found the tip of the iceberg: the high ionization of the outflowing gas may explain why it is commonly difficult to detect UFOs in AGN and possibly suggest that we may underestimate their actual feedback. We have also found a tentative correlation between the outflow velocity and the luminosity, which is expected from theoretical predictions of radiation-pressure-driven winds. This trend is rather marginal due to the Fe XXV-XXVI degeneracy. Further work is needed to break such degeneracy through time-resolved spectroscopy.

  19. Fluid outflows from Venus impact craters - Analysis from Magellan data

    Science.gov (United States)

    Asimow, Paul D.; Wood, John A.

    1992-01-01

    Many impact craters on Venus have unusual outflow features originating in or under the continuous ejecta blankets and continuing downhill into the surrounding terrain. These features clearly resulted from flow of low-viscosity fluids, but the identity of those fluids is not clear. In particular, it should not be assumed a priori that the fluid is an impact melt. A number of candidate processes by which impact events might generate the observed features are considered, and predictions are made concerning the rheological character of flows produce by each mechanism. A sample of outflows was analyzed using Magellan images and a model of unconstrained Bingham plastic flow on inclined planes, leading to estimates of viscosity and yield strength for the flow materials. It is argued that at least two different mechanisms have produced outflows on Venus: an erosive, channel-forming process and a depositional process. The erosive fluid is probably an impact melt, but the depositional fluid may consist of fluidized solid debris, vaporized material, and/or melt.

  20. Lagrangian averaging with geodesic mean.

    Science.gov (United States)

    Oliver, Marcel

    2017-11-01

    This paper revisits the derivation of the Lagrangian averaged Euler (LAE), or Euler- α equations in the light of an intrinsic definition of the averaged flow map as the geodesic mean on the volume-preserving diffeomorphism group. Under the additional assumption that first-order fluctuations are statistically isotropic and transported by the mean flow as a vector field, averaging of the kinetic energy Lagrangian of an ideal fluid yields the LAE Lagrangian. The derivation presented here assumes a Euclidean spatial domain without boundaries.

  1. Determinants of Foreign Direct Investments Outflow From a Developing Country: the Case of Turkey

    Directory of Open Access Journals (Sweden)

    Gokhan Onder

    2013-09-01

    Full Text Available Foreign direct investments (FDI outflows of Turkey have remarkably been raising over the last decade. This rapid increase brings about the need for questioning the determinants of FDI outflows. The aim of this paper is to estimate the factors affecting outflow FDI from Turkey from 2002 to 2011 by using Prais-Winsten regression analysis. According to estimation results, population, infrastructure, percapita gross domestic product of the host country, and home country exports to the host country are the factors having positive effects on outflow FDI. We found, on the other hand, that the annual inflation rate of the host country, its tax rate collected from commercial profit, and its distance from Turkey have a negative relation with investment outflows. Moreover our results show that while investment outflows to developed countries are in the form of horizontal investments, investment outflows to developing countries are in the form of vertical investments.

  2. Averaging in spherically symmetric cosmology

    International Nuclear Information System (INIS)

    Coley, A. A.; Pelavas, N.

    2007-01-01

    The averaging problem in cosmology is of fundamental importance. When applied to study cosmological evolution, the theory of macroscopic gravity (MG) can be regarded as a long-distance modification of general relativity. In the MG approach to the averaging problem in cosmology, the Einstein field equations on cosmological scales are modified by appropriate gravitational correlation terms. We study the averaging problem within the class of spherically symmetric cosmological models. That is, we shall take the microscopic equations and effect the averaging procedure to determine the precise form of the correlation tensor in this case. In particular, by working in volume-preserving coordinates, we calculate the form of the correlation tensor under some reasonable assumptions on the form for the inhomogeneous gravitational field and matter distribution. We find that the correlation tensor in a Friedmann-Lemaitre-Robertson-Walker (FLRW) background must be of the form of a spatial curvature. Inhomogeneities and spatial averaging, through this spatial curvature correction term, can have a very significant dynamical effect on the dynamics of the Universe and cosmological observations; in particular, we discuss whether spatial averaging might lead to a more conservative explanation of the observed acceleration of the Universe (without the introduction of exotic dark matter fields). We also find that the correlation tensor for a non-FLRW background can be interpreted as the sum of a spatial curvature and an anisotropic fluid. This may lead to interesting effects of averaging on astrophysical scales. We also discuss the results of averaging an inhomogeneous Lemaitre-Tolman-Bondi solution as well as calculations of linear perturbations (that is, the backreaction) in an FLRW background, which support the main conclusions of the analysis

  3. Magnetic Topology and Ion Outflow in Mars' Magnetotail

    Science.gov (United States)

    Mitchell, D. L.; Xu, S.; McFadden, J. P.; Hara, T.; Luhmann, J. G.; Mazelle, C. X.; Andersson, L.; DiBraccio, G. A.; Connerney, J. E. P.

    2017-12-01

    Planetary ion outflow down the Martian magnetotail could be an important atmospheric loss mechanism. This process depends on magnetic connectivity to the day-side ionosphere and on acceleration of ions to escape velocity. The Mars Atmosphere and Volatile Evolution (MAVEN) mission has obtained comprehensive ion, electron, and magnetic field data in Mars' magnetotail. The spacecraft is in a 75°-inclination, elliptical orbit that samples altitudes from 150 to 6200 km. As the orbit precesses, it sweeps through the tail at a variety of altitudes in this range. Data from the Solar Wind Electron Analyzer (SWEA) and Magnetometer (MAG) are used to determine the magnetic field topology in the tail at high cadence (every 2-4 seconds), and in particular whether field lines are open, closed, or draped, and if open whether they have access to the day-side or night-side ionosphere. Simultaneous observations by the Supra-Thermal and Thermal Ion Composition (STATIC) instrument and the Langmuir Probe and Waves (LPW) experiment are used to measure the density, composition, and velocity of planetary plasma on these field lines. We find that magnetic topology in the tail is complex and variable, and is influenced by the IMF polarity and the orientation of Mars' crustal magnetic fields with respect to the Sun. We find that planetary ion outflow occurs on both open and draped field lines. On open field lines, outflow tends to occur parallel to the field line, with colder, denser, and slower outflow on field lines connected to the day-side ionosphere (Fig. 1). On these same field lines (after correction for the spacecraft potential) a shift in the position of the He-II photoelectron feature indicates a 1-Volt parallel electric potential directed away from the planet. Except for H+ and occasionally O+, this potential is insufficient by itself to accelerate planetary ions to escape velocity. Outflow is warmer, less dense, and faster moving on draped field lines. In this case, the ion bulk

  4. Averaging models: parameters estimation with the R-Average procedure

    Directory of Open Access Journals (Sweden)

    S. Noventa

    2010-01-01

    Full Text Available The Functional Measurement approach, proposed within the theoretical framework of Information Integration Theory (Anderson, 1981, 1982, can be a useful multi-attribute analysis tool. Compared to the majority of statistical models, the averaging model can account for interaction effects without adding complexity. The R-Average method (Vidotto & Vicentini, 2007 can be used to estimate the parameters of these models. By the use of multiple information criteria in the model selection procedure, R-Average allows for the identification of the best subset of parameters that account for the data. After a review of the general method, we present an implementation of the procedure in the framework of R-project, followed by some experiments using a Monte Carlo method.

  5. Variability of cirrus clouds in a convective outflow during the Hibiscus campaign

    Science.gov (United States)

    Fierli, F.; di Donfrancesco, G.; Cairo, F.; Marécal, V.; Zampieri, M.; Orlandi, E.; Durry, G.

    2008-08-01

    Light-weight microlidar and water vapour measurements were taken on-board a stratospheric balloon during the HIBISCUS 2004 campaign, held in Bauru, Brazil (49° W, 22° S). Cirrus clouds were observed throughout the flight between 12 and 15 km height with a high mesoscale variability in optical and microphysical properties. It was found that the cirrus clouds were composed of different layers characterized by marked differences in height, thickness and optical properties. Simultaneous water vapour observations show that the different layers are characterized by different values of the saturation with respect to ice. A mesoscale simulation and a trajectory analysis clearly revealed that the clouds had formed in the outflow of a large and persistent convective region and that the observed variability of the optical properties and of the cloud structure is likely linked to the different residence times of the convectively-processed air in the upper troposphere.

  6. DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITH SUZAKU

    International Nuclear Information System (INIS)

    Tombesi, F.; Sambruna, R. M.; Mushotzky, R. F.; Reeves, J. N.; Gofford, J.; Braito, V.; Ballo, L.; Cappi, M.

    2010-01-01

    We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v ≅ 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log ξ ≅ 4-5.6 erg s -1 cm and column densities of N H ≅ 10 22 -10 23 cm -2 . These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within ∼0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

  7. Evaluations of average level spacings

    International Nuclear Information System (INIS)

    Liou, H.I.

    1980-01-01

    The average level spacing for highly excited nuclei is a key parameter in cross section formulas based on statistical nuclear models, and also plays an important role in determining many physics quantities. Various methods to evaluate average level spacings are reviewed. Because of the finite experimental resolution, to detect a complete sequence of levels without mixing other parities is extremely difficult, if not totally impossible. Most methods derive the average level spacings by applying a fit, with different degrees of generality, to the truncated Porter-Thomas distribution for reduced neutron widths. A method that tests both distributions of level widths and positions is discussed extensivey with an example of 168 Er data. 19 figures, 2 tables

  8. High average power supercontinuum sources

    Indian Academy of Sciences (India)

    The physical mechanisms and basic experimental techniques for the creation of high average spectral power supercontinuum sources is briefly reviewed. We focus on the use of high-power ytterbium-doped fibre lasers as pump sources, and the use of highly nonlinear photonic crystal fibres as the nonlinear medium.

  9. Simulation

    DEFF Research Database (Denmark)

    Gould, Derek A; Chalmers, Nicholas; Johnson, Sheena J

    2012-01-01

    Recognition of the many limitations of traditional apprenticeship training is driving new approaches to learning medical procedural skills. Among simulation technologies and methods available today, computer-based systems are topical and bring the benefits of automated, repeatable, and reliable p...... performance assessments. Human factors research is central to simulator model development that is relevant to real-world imaging-guided interventional tasks and to the credentialing programs in which it would be used....

  10. ERUPTIVE VARIABLE STARS AND OUTFLOWS IN SERPENS NW

    Energy Technology Data Exchange (ETDEWEB)

    Hodapp, Klaus W. [Institute for Astronomy, University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720 (United States); Chini, Rolf; Watermann, Ramon; Lemke, Roland, E-mail: hodapp@ifa.hawaii.edu [Ruhr Universitaet Bochum, Astronomisches Institut, Universitaetsstrasse 150, D-44801 Bochum (Germany)

    2012-01-01

    We study the outflow activity, photometric variability, and morphology of three very young stellar objects in the Serpens NW star-forming region: OO Serpentis, EC 37 (V370 Ser), and EC 53 (V371 Ser). High spatial resolution Keck/NIRC2 laser guide star adaptive optics images obtained in 2007 and 2009 in broadband K and in a narrowband filter centered on the 1-0 S(1) emission line of H{sub 2} allow us to identify the outflows from all three objects. We also present new, seeing-limited data on the photometric evolution of the OO Ser reflection nebula and re-analyze previously published data. We find that OO Ser declined in brightness from its outburst peak in 1995 to about 2003, but that this decline has recently stopped and actually reversed itself in some areas of the reflection nebula. The morphology and proper motions of the shock fronts MHO 2218 near EC 37 suggest that they all originate in EC 37 and that this is an outflow seen nearly along its axis. We identify an H{sub 2} jet emerging from the cometary nebula EC 53. The star illuminating EC 53 is periodically variable with a period of 543 days and has a close-by, non-variable companion at a projected distance of 92 AU. We argue that the periodic variability is the result of accretion instabilities triggered by another very close, not directly observable, binary companion and that EC 53 can be understood in the model of a multiple system developing into a hierarchical configuration.

  11. DENSE CLUMPS AND CANDIDATES FOR MOLECULAR OUTFLOWS IN W40

    Energy Technology Data Exchange (ETDEWEB)

    Shimoikura, Tomomi; Dobashi, Kazuhito [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Nakamura, Fumitaka; Hara, Chihomi; Kawabe, Ryohei [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Tanaka, Tomohiro [Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Shimajiri, Yoshito [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Sugitani, Kouji, E-mail: ikura@u-gakugei.ac.jp [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501 (Japan)

    2015-06-20

    We report the results of the {sup 12}CO (J = 3−2) and HCO{sup +} (J = 4−3) observations of the W40 H ii region with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope (HPBW ≃ 22″) to search for molecular outflows and dense clumps. We found that the velocity field in the region is highly complex, consisting of at least four distinct velocity components at V{sub LSR} ≃ 3, 5, 7, and 10 km s{sup −1}. The ∼7 km s{sup −1} component represents the systemic velocity of cold gas surrounding the entire region, and causes heavy absorption in the {sup 12}CO spectra over the velocity range 6 ≲ V{sub LSR} ≲ 9 km s{sup −1}. The ∼5 and ∼10 km s{sup −1} components exhibit high {sup 12}CO temperature (≳40 K) and are found mostly around the H ii region, suggesting that these components are likely to be tracing dense gas interacting with the expanding shell around the H ii region. Based on the {sup 12}CO data, we identified 13 regions of high velocity gas, which we interpret as candidate outflow lobes. Using the HCO{sup +} data, we also identified six clumps and estimated their physical parameters. On the basis of the ASTE data and near-infrared images from 2MASS, we present an updated three-dimensional model of this region. In order to investigate molecular outflows in W40, the SiO (J = 1−0, v = 0) emission line and some other emission lines at 40 GHz were also observed with the 45 m telescope at the Nobeyama Radio Observatory, but they were not detected at the present sensitivity.

  12. Atmospheric pollutant outflow from southern Asia: a review

    Directory of Open Access Journals (Sweden)

    M. G. Lawrence

    2010-11-01

    Full Text Available Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ, located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern Asian atmospheric pollutant outflow and its large scale

  13. Atmospheric pollutant outflow from southern Asia: a review

    Science.gov (United States)

    Lawrence, M. G.; Lelieveld, J.

    2010-11-01

    Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ), located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern Asian atmospheric pollutant outflow and its large scale effects. An outlook

  14. Negative and Positive Outflow-Feedback in Nearby (U)LIRGs

    Energy Technology Data Exchange (ETDEWEB)

    Cazzoli, Sara, E-mail: sara@iaa.es [Instituto de Astrofisica de Andalucia (CSIC), Granada (Spain)

    2017-12-15

    The starburst-AGN coexistence in local (U)LIRGs makes these galaxies excellent laboratories for the study of stellar and AGN outflows and feedback. Outflows regulate star formation and AGN activity, redistributing gas, dust and metals over large scales in the interstellar and intergalactic media (negative feedback) being also considered to be able to undergo vigorous star formation (positive feedback). In this contribution, I will summarize the results from a search for outflows in a sample of nearby 38 local (U)LIRG systems observed with VIMOS/VLT integral field unit. For two galaxies of the sample I will detail the outflow properties and discuss the observational evidence for negative and positive outflow-feedback. The assessment of both negative and positive feedback effects represent a novel approach toward a comprehensive understanding of the impact of outflow feedback in the galaxy evolution.

  15. Statistics on exponential averaging of periodograms

    Energy Technology Data Exchange (ETDEWEB)

    Peeters, T.T.J.M. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Ciftcioglu, Oe. [Istanbul Technical Univ. (Turkey). Dept. of Electrical Engineering

    1994-11-01

    The algorithm of exponential averaging applied to subsequent periodograms of a stochastic process is used to estimate the power spectral density (PSD). For an independent process, assuming the periodogram estimates to be distributed according to a {chi}{sup 2} distribution with 2 degrees of freedom, the probability density function (PDF) of the PSD estimate is derived. A closed expression is obtained for the moments of the distribution. Surprisingly, the proof of this expression features some new insights into the partitions and Eulers infinite product. For large values of the time constant of the averaging process, examination of the cumulant generating function shows that the PDF approximates the Gaussian distribution. Although restrictions for the statistics are seemingly tight, simulation of a real process indicates a wider applicability of the theory. (orig.).

  16. Statistics on exponential averaging of periodograms

    International Nuclear Information System (INIS)

    Peeters, T.T.J.M.; Ciftcioglu, Oe.

    1994-11-01

    The algorithm of exponential averaging applied to subsequent periodograms of a stochastic process is used to estimate the power spectral density (PSD). For an independent process, assuming the periodogram estimates to be distributed according to a χ 2 distribution with 2 degrees of freedom, the probability density function (PDF) of the PSD estimate is derived. A closed expression is obtained for the moments of the distribution. Surprisingly, the proof of this expression features some new insights into the partitions and Eulers infinite product. For large values of the time constant of the averaging process, examination of the cumulant generating function shows that the PDF approximates the Gaussian distribution. Although restrictions for the statistics are seemingly tight, simulation of a real process indicates a wider applicability of the theory. (orig.)

  17. When good = better than average

    Directory of Open Access Journals (Sweden)

    Don A. Moore

    2007-10-01

    Full Text Available People report themselves to be above average on simple tasks and below average on difficult tasks. This paper proposes an explanation for this effect that is simpler than prior explanations. The new explanation is that people conflate relative with absolute evaluation, especially on subjective measures. The paper then presents a series of four studies that test this conflation explanation. These tests distinguish conflation from other explanations, such as differential weighting and selecting the wrong referent. The results suggest that conflation occurs at the response stage during which people attempt to disambiguate subjective response scales in order to choose an answer. This is because conflation has little effect on objective measures, which would be equally affected if the conflation occurred at encoding.

  18. TETHER-CUTTING RECONNECTION BETWEEN TWO SOLAR FILAMENTS TRIGGERING OUTFLOWS AND A CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Huadong; Zhang, Jun; Li, Leping [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ma, Suli, E-mail: hdchen@nao.cas.cn [College of Science, China University of Petroleum, Qingdao 266580 (China)

    2016-02-20

    Triggering mechanisms of solar eruptions have long been a challenge. A few previous case studies have indicated that preceding gentle filament merging via magnetic reconnection may launch following intense eruption, according to the tether-cutting (TC) model. However, the detailed process of TC reconnection between filaments has not been exhibited yet. In this work, we report the high-resolution observations from the Interface Region Imaging Spectrometer (IRIS) of TC reconnection between two sheared filaments in NOAA active region 12146. The TC reconnection commenced on ∼15:35 UT on 2014 August 29 and triggered an eruptive GOES C4.3-class flare ∼8 minutes later. An associated coronal mass ejection appeared in the field of view of the Solar and Heliospheric Observatory/LASCO C2 about 40 minutes later. Thanks to the high spatial resolution of IRIS data, bright plasma outflows generated by the TC reconnection are clearly observed, which moved along the subarcsecond fine-scale flux tube structures in the erupting filament. Based on the imaging and spectral observations, the mean plane-of-sky and line-of-sight velocities of the TC reconnection outflows are separately measured to be ∼79 and 86 km s{sup −1}, which derives an average real speed of ∼120 km s{sup −1}. In addition, it is found that spectral features, such as peak intensities, Doppler shifts, and line widths in the TC reconnection region are evidently enhanced compared to those in the nearby region just before the flare.

  19. Blowing in the Milky Way Wind: Neutral Hydrogen Clouds Tracing the Galactic Nuclear Outflow

    Science.gov (United States)

    Di Teodoro, Enrico M.; McClure-Griffiths, N. M.; Lockman, Felix J.; Denbo, Sara R.; Endsley, Ryan; Ford, H. Alyson; Harrington, Kevin

    2018-03-01

    We present the results of a new sensitive survey of neutral hydrogen above and below the Galactic Center with the Green Bank Telescope. The observations extend up to Galactic latitude | b| resolution of 9.‧5 and an average rms brightness temperature noise of 40 mK in a 1 {km} {{{s}}}-1 channel. The survey reveals the existence of a population of anomalous high-velocity clouds extending up to heights of about 1.5 kpc from the Galactic plane and showing no signature of Galactic rotation. These clouds have local standard of rest velocities | {V}LSR}| ≲ 360 {km} {{{s}}}-1, and assuming a Galactic Center origin, they have sizes of a few tens of parsec and neutral hydrogen masses spanning 10{--}{10}5 {M}ȯ . Accounting for selection effects, the cloud population is symmetric in longitude, latitude, and V LSR. We model the cloud kinematics in terms of an outflow expanding from the Galactic Center and find the population consistent with being material moving with radial velocity {V}{{w}}≃ 330 {km} {{{s}}}-1 distributed throughout a bicone with opening angle α > 140^\\circ . This simple model implies an outflow luminosity {L}{{w}}> 3× {10}40 erg s‑1 over the past 10 Myr, consistent with star formation feedback in the inner region of the Milky Way, with a cold gas mass-loss rate ≲ 0.1 {{M}ȯ {yr}}-1. These clouds may represent the cold gas component accelerated in the nuclear wind driven by our Galaxy, although some of the derived properties challenge current theoretical models of the entrainment process.

  20. Autoregressive Moving Average Graph Filtering

    OpenAIRE

    Isufi, Elvin; Loukas, Andreas; Simonetto, Andrea; Leus, Geert

    2016-01-01

    One of the cornerstones of the field of signal processing on graphs are graph filters, direct analogues of classical filters, but intended for signals defined on graphs. This work brings forth new insights on the distributed graph filtering problem. We design a family of autoregressive moving average (ARMA) recursions, which (i) are able to approximate any desired graph frequency response, and (ii) give exact solutions for tasks such as graph signal denoising and interpolation. The design phi...

  1. Averaging Robertson-Walker cosmologies

    International Nuclear Information System (INIS)

    Brown, Iain A.; Robbers, Georg; Behrend, Juliane

    2009-01-01

    The cosmological backreaction arises when one directly averages the Einstein equations to recover an effective Robertson-Walker cosmology, rather than assuming a background a priori. While usually discussed in the context of dark energy, strictly speaking any cosmological model should be recovered from such a procedure. We apply the scalar spatial averaging formalism for the first time to linear Robertson-Walker universes containing matter, radiation and dark energy. The formalism employed is general and incorporates systems of multiple fluids with ease, allowing us to consider quantitatively the universe from deep radiation domination up to the present day in a natural, unified manner. Employing modified Boltzmann codes we evaluate numerically the discrepancies between the assumed and the averaged behaviour arising from the quadratic terms, finding the largest deviations for an Einstein-de Sitter universe, increasing rapidly with Hubble rate to a 0.01% effect for h = 0.701. For the ΛCDM concordance model, the backreaction is of the order of Ω eff 0 ≈ 4 × 10 −6 , with those for dark energy models being within a factor of two or three. The impacts at recombination are of the order of 10 −8 and those in deep radiation domination asymptote to a constant value. While the effective equations of state of the backreactions in Einstein-de Sitter, concordance and quintessence models are generally dust-like, a backreaction with an equation of state w eff < −1/3 can be found for strongly phantom models

  2. Baseline-dependent averaging in radio interferometry

    Science.gov (United States)

    Wijnholds, S. J.; Willis, A. G.; Salvini, S.

    2018-05-01

    This paper presents a detailed analysis of the applicability and benefits of baseline-dependent averaging (BDA) in modern radio interferometers and in particular the Square Kilometre Array. We demonstrate that BDA does not affect the information content of the data other than a well-defined decorrelation loss for which closed form expressions are readily available. We verify these theoretical findings using simulations. We therefore conclude that BDA can be used reliably in modern radio interferometry allowing a reduction of visibility data volume (and hence processing costs for handling visibility data) by more than 80 per cent.

  3. The digital aqueous humor outflow meter: an alternative tool for screening of the human eye outflow facility

    Directory of Open Access Journals (Sweden)

    Vassilios P Kozobolis

    2010-08-01

    Full Text Available Vassilios P Kozobolis, Eleftherios I Paschalis, Nikitas C Foudoulakis, Stavrenia C Koukoula, Georgios LabirisDepartment of Ophthalmology and Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, GreecePurpose: To develop, characterize, and validate a prototype digital aqueous humor outflow tonographer (DAHOM.Material and methods: The DAHOM was developed, characterized, and validated in three phases. Phase 1 involved construction of the sensor. This was broadly based on the fundamental design of a typical Schiotz tonographer with a series of improvements, including corneal indentation, which was converted to an electrical signal via a linear variable differential transducer, an analog signal which was converted to digital via ADC circuitry, and digital data acquisition and processing which was made possible by a serial port interface. Phase 2 comprised development of software for automated assessment of the outflow facility. Automated outflow facility assessment incorporated a series of fundamental improvements in comparison with traditional techniques, including software-based filtering of ripple noise and extreme variations, rigidity impact analysis, and evaluation of the impact of patient age, central corneal thickness, and ocular axial length. Phase 3 comprised characterization and validation of DAHOM, for which we developed an experimental setup using porcine cadaver eyes. DAHOM’s repeatability was evaluated by means of Cronbach’s alpha and intraclass correlation coefficient. The level of agreement with a standard Schiotz tonographer was evaluated by means of paired t-tests and Bland-Altman analysis in human eyes.Results: The experimental setup provided the necessary data for the characterization of DAHOM. A fourth order polynomial equation provided excellent fit (R square >0.999. DAHOM demonstrated high repeatability (Cronbach’s alpha ≥0.997; intraclass correlation coefficient ≥0.987 and an adequate level of

  4. Simulation

    CERN Document Server

    Ross, Sheldon

    2006-01-01

    Ross's Simulation, Fourth Edition introduces aspiring and practicing actuaries, engineers, computer scientists and others to the practical aspects of constructing computerized simulation studies to analyze and interpret real phenomena. Readers learn to apply results of these analyses to problems in a wide variety of fields to obtain effective, accurate solutions and make predictions about future outcomes. This text explains how a computer can be used to generate random numbers, and how to use these random numbers to generate the behavior of a stochastic model over time. It presents the statist

  5. Device for preventing coolant outflow in a reactor

    International Nuclear Information System (INIS)

    Nemoto, Kiyomitsu; Mochizuki, Keiichi.

    1975-01-01

    Object: To prevent outflow of coolant from a reactor vessel even in an occurrence of leaking trouble at a low position in a primary cooling system or the like in the reactor vessel. Structure: An inlet at the foremost end of a coolant inlet pipe inserted into a reactor vessel is arranged at a level lower than a core, and a check valve is positioned at a level higher than the core in a rising portion of the inlet. In normal condition, the check valve is pushed up by discharge pressure of a main circulating pump and remains closed, and hence, producing no flow loss of coolant, sodium. However, when a trouble such as rupture occurs at the lower position in the primary cooling system, the attractive force for allowing the coolant to back-flow outside the reactor vessel and the load force of the coolant within the reactor vessel cause the check valve to actuate, as a consequence of which a liquid level of the coolant downwardly moves to the position of the check valve to intake the cover gases into a gas intake, thereby cutting off a flow passage of the coolant to stop outflow thereof. (Kamimura, M.)

  6. The sacral autonomic outflow is parasympathetic: Langley got it right.

    Science.gov (United States)

    Horn, John P

    2018-04-01

    A recent developmental study of gene expression by Espinosa-Medina, Brunet and colleagues sparked controversy by asserting a revised nomenclature for divisions of the autonomic motor system. Should we re-classify the sacral autonomic outflow as sympathetic, as now suggested, or does it rightly belong to the parasympathetic system, as defined by Langley nearly 100 years ago? Arguments for rejecting Espinosa-Medina, Brunet et al.'s scheme subsequently appeared in e-letters and brief reviews. A more recent commentary in this journal by Brunet and colleagues responded to these criticisms by labeling Langley's scheme as a historical myth perpetuated by ignorance. In reaction to this heated exchange, I now examine both sides to the controversy, together with purported errors by the pioneers in the field. I then explain, once more, why the sacral outflow should remain known as parasympathetic, and outline suggestions for future experimentation to advance the understanding of cellular identity in the autonomic motor system.

  7. Advection-dominated Inflow/Outflows from Evaporating Accretion Disks.

    Science.gov (United States)

    Turolla; Dullemond

    2000-03-01

    In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture, the ADAF fills the central cavity evacuated by the SSD and extends beyond the transition radius into a coronal region. We find that, because of global angular momentum conservation, a significant fraction of the hot gas flows away from the black hole, forming a transsonic wind, unless the injection rate depends only weakly on radius (if r2sigma&d2;~r-xi, xiBernoulli number of the inflowing gas is negative if the transition radius is less, similar100 Schwarzschild radii, so matter falling into the hole is gravitationally bound. The ratio of inflowing to outflowing mass is approximately 1/2, so in these solutions the accretion rate is of the same order as in standard ADAFs and much larger than in advection-dominated inflow/outflow models. The possible relevance of evaporation-fed solutions to accretion flows in black hole X-ray binaries is briefly discussed.

  8. Burst Activity and Heart Rhythm Modulation in the Sympathetic Outflow to the Heart

    National Research Council Canada - National Science Library

    Baselli, G

    2001-01-01

    In 13 decerebrate, artificially ventilated cats preganglionic sympathetic outflow to the heart was recorded with ECG and ventilation signal, A novel algorithm was implemented that extracts weighted...

  9. Low-redshift Lyman limit systems as diagnostics of cosmological inflows and outflows

    Science.gov (United States)

    Hafen, Zachary; Faucher-Giguère, Claude-André; Anglés-Alcázar, Daniel; Kereš, Dušan; Feldmann, Robert; Chan, T. K.; Quataert, Eliot; Murray, Norman; Hopkins, Philip F.

    2017-08-01

    We use cosmological hydrodynamic simulations with stellar feedback from the FIRE (Feedback In Realistic Environments) project to study the physical nature of Lyman limit systems (LLSs) at z ≤ 1. At these low redshifts, LLSs are closely associated with dense gas structures surrounding galaxies, such as galactic winds, dwarf satellites and cool inflows from the intergalactic medium. Our analysis is based on 14 zoom-in simulations covering the halo mass range Mh ≈ 109-1013 M⊙ at z = 0, which we convolve with the dark matter halo mass function to produce cosmological statistics. We find that the majority of cosmologically selected LLSs are associated with haloes in the mass range 1010 ≲ Mh ≲ 1012 M⊙. The incidence and H I column density distribution of simulated absorbers with columns in the range 10^{16.2} ≤ N_{H I} ≤ 2× 10^{20} cm-2 are consistent with observations. High-velocity outflows (with radial velocity exceeding the halo circular velocity by a factor of ≳ 2) tend to have higher metallicities ([X/H] ˜ -0.5) while very low metallicity ([X/H] standard deviation) [X/H] = -0.9 (0.4) and does not show significant evidence for bimodality, in contrast to recent observational studies, but consistent with LLSs arising from haloes with a broad range of masses and metallicities.

  10. Compact Starburst Galaxies with Fast Outflows: Spatially Resolved Stellar Mass Profiles

    Science.gov (United States)

    Gottlieb, Sophia; Diamond-Stanic, Aleksandar; Lipscomb, Charles; Ohene, Senyo; Rines, Josh; Moustakas, John; Sell, Paul; Tremonti, Christy; Coil, Alison; Rudnick, Gregory; Hickox, Ryan C.; Geach, James; Kepley, Amanda

    2018-01-01

    Powerful galactic winds driven by stellar feedback and black hole accretion are thought to play an important role in regulating star formation in galaxies. In particular, strong stellar feedback from supernovae, stellar winds, radiation pressure, and cosmic rays is required by simulations of star-forming galaxies to prevent the vast majority of baryons from cooling and collapsing to form stars. However, it remains unclear whether these stellar processes play a significant role in expelling gas and shutting down star formation in massive progenitors of quiescent galaxies. What are the limits of stellar feedback? We present multi-band photometry with HST/WFC3 (F475W, F814W, F160W) for a dozen compact starburst galaxies at z~0.6 with half-light radii that suggest incredibly large central escape velocities. These massive galaxies are driving fast (>1000 km/s) outflows that have been previously attributed to stellar feedback associated with the compact (r~100 pc) starburst. But how compact is the stellar mass? In the context of the stellar feedback hypothesis, it is unclear whether these fast outflows are being driven at velocities comparable to the escape velocity of an incredibly dense stellar system (as predicted by some models of radiation-pressure winds) or at velocities that exceed the central escape velocity by large factor. Our spatially resolved measurements with HST show that the stellar mass is more extended than the light, and this requires that the physical mechanism responsible for driving the winds must be able to launch gas at velocities that are factors of 5-10 beyond the central escape velocity.

  11. Lagrangian Photochemical Box-Model Calculations of Asian Pacific Rim Outflow During TRACE-P

    Science.gov (United States)

    Hamlin, A.; Crawford, J.; Olson, J.; Avery, M.; Sachse, G.; Barrick, J.; Blake, D.; Tan, D.; Sandholm, S.; Kondo, Y.; Singh, H.; Eisele, F.; Zondlo, M.; Flocke, F.; Talbot, R.

    2006-12-01

    NASA's TRACE-P (TRAnsport and Chemical Evolution over the Pacific) mission was conducted over the northwestern Pacific February-April, 2001. During two transit flights across the Pacific, extensive pollution was observed from an Asian outflow event that split into two branches over the central Pacific, one subsiding and moving southward over the central Pacific and the other continuing eastward in the upper troposphere. The subsiding branch was observed as a widespread stagnant pollution layer between 2 and 4 km over the central Pacific during transit flights from Kona, HI to Guam. In this region, high levels of O3 (70 ppbv), CO (217 ppbv), and NOx (114 pptv) were well in excess of typical values observed during TRACE-P along the Asian coast. Evidence suggests that the subsiding branch experienced extensive photochemical processing compared to the branch that remained at altitude. To examine the processes controlling the chemical evolution of ozone and its precursors in this outflow event, data collected during the TRACE-P mission have been combined with lagrangian photochemical box model calculations. One of the largest sources of uncertainty in these calculations was associated with predicted water vapor levels along the transport trajectories calculated using the HYSPLIT model. Water vapor levels predicted by HYSPLIT trajectory calculations in the subsiding layer ranged from 3390 to 4880 ppm, while the median level observed in the pollution layer was only 637 ppm. Simulations of ozone production and associated radical chemistry differed dramatically when using water vapor levels based on trajectory calculations versus observed water vapor levels. Levels of PAN and HO2NO2, NOx reservoir species, are also influenced by uncertainties in temperature along the trajectories. These results highlight the importance of accurately representing the humidification and warming of subsiding air masses in 3-D chemical- transport models.

  12. The launch region of the SVS 13 outflow and jet

    Energy Technology Data Exchange (ETDEWEB)

    Hodapp, Klaus W. [Institute for Astronomy, University of Hawaii, 640 North Aohoku Place, Hilo, HI 96720 (United States); Chini, Rolf, E-mail: hodapp@ifa.hawaii.edu, E-mail: rolf.chini@astro.ruhr-uni-bochum.de [Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150, D-44801 Bochum (Germany)

    2014-10-20

    We present the results of Keck telescope laser adaptive-optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.''2 long microjet traced by the emission of shock-excited [Fe II]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H{sub 2} 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (P.A. ≈ 145°) to the southeast of SVS 13, there is clear indication that prior bubble ejections were pointed in different directions. Within these variations, a clear connection between the newly observed bubble ejection events and the well-known, poorly collimated HH 7-11 system of Herbig-Haro objects is established. The astrometry of the youngest of the expanding shock fronts at three epochs, covering a timespan of over 2 yr, gives kinematic ages for two of these bubbles. The kinematic age of the youngest bubble is slightly older than the historically observed last photometric outburst of SVS 13 in 1990, consistent with that event, launching the bubble and some deceleration of its expansion. A re-evaluation of historic infrared photometry and new data show that SVS 13 has not yet returned to its brightness before that outburst and thus reveal behavior similar to FUor outbursts, albeit with a smaller amplitude. We postulate that the creation of a series of bubbles and the changes in outflow direction are indicative of a precessing disk and accretion events triggered by a repetitive phenomenon possibly linked to the orbit of a close binary companion. However, our high-resolution images in the H and K bands do not directly detect any companion object. We have tried, but failed, to detect the kinematic rotation signature of the microjet in the [Fe II] emission line at 1.644 μm.

  13. The Launch Region of the SVS 13 Outflow and Jet

    Science.gov (United States)

    Hodapp, Klaus W.; Chini, Rolf

    2014-10-01

    We present the results of Keck telescope laser adaptive-optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.''2 long microjet traced by the emission of shock-excited [Fe II]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H2 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (P.A. ≈ 145°) to the southeast of SVS 13, there is clear indication that prior bubble ejections were pointed in different directions. Within these variations, a clear connection between the newly observed bubble ejection events and the well-known, poorly collimated HH 7-11 system of Herbig-Haro objects is established. The astrometry of the youngest of the expanding shock fronts at three epochs, covering a timespan of over 2 yr, gives kinematic ages for two of these bubbles. The kinematic age of the youngest bubble is slightly older than the historically observed last photometric outburst of SVS 13 in 1990, consistent with that event, launching the bubble and some deceleration of its expansion. A re-evaluation of historic infrared photometry and new data show that SVS 13 has not yet returned to its brightness before that outburst and thus reveal behavior similar to FUor outbursts, albeit with a smaller amplitude. We postulate that the creation of a series of bubbles and the changes in outflow direction are indicative of a precessing disk and accretion events triggered by a repetitive phenomenon possibly linked to the orbit of a close binary companion. However, our high-resolution images in the H and K bands do not directly detect any companion object. We have tried, but failed, to detect the kinematic rotation signature of the microjet in the [Fe II] emission line at 1.644 μm.

  14. The launch region of the SVS 13 outflow and jet

    International Nuclear Information System (INIS)

    Hodapp, Klaus W.; Chini, Rolf

    2014-01-01

    We present the results of Keck telescope laser adaptive-optics integral field spectroscopy with OSIRIS of the innermost regions of the NGC 1333 SVS 13 outflow that forms the system of Herbig-Haro objects 7-11. We find a bright 0.''2 long microjet traced by the emission of shock-excited [Fe II]. Beyond the extent of this jet, we find a series of bubbles and fragments of bubbles that are traced in the lower excitation H 2 1-0 S(1) line. While the most recent outflow activity is directed almost precisely (P.A. ≈ 145°) to the southeast of SVS 13, there is clear indication that prior bubble ejections were pointed in different directions. Within these variations, a clear connection between the newly observed bubble ejection events and the well-known, poorly collimated HH 7-11 system of Herbig-Haro objects is established. The astrometry of the youngest of the expanding shock fronts at three epochs, covering a timespan of over 2 yr, gives kinematic ages for two of these bubbles. The kinematic age of the youngest bubble is slightly older than the historically observed last photometric outburst of SVS 13 in 1990, consistent with that event, launching the bubble and some deceleration of its expansion. A re-evaluation of historic infrared photometry and new data show that SVS 13 has not yet returned to its brightness before that outburst and thus reveal behavior similar to FUor outbursts, albeit with a smaller amplitude. We postulate that the creation of a series of bubbles and the changes in outflow direction are indicative of a precessing disk and accretion events triggered by a repetitive phenomenon possibly linked to the orbit of a close binary companion. However, our high-resolution images in the H and K bands do not directly detect any companion object. We have tried, but failed, to detect the kinematic rotation signature of the microjet in the [Fe II] emission line at 1.644 μm.

  15. Topological quantization of ensemble averages

    International Nuclear Information System (INIS)

    Prodan, Emil

    2009-01-01

    We define the current of a quantum observable and, under well-defined conditions, we connect its ensemble average to the index of a Fredholm operator. The present work builds on a formalism developed by Kellendonk and Schulz-Baldes (2004 J. Funct. Anal. 209 388) to study the quantization of edge currents for continuous magnetic Schroedinger operators. The generalization given here may be a useful tool to scientists looking for novel manifestations of the topological quantization. As a new application, we show that the differential conductance of atomic wires is given by the index of a certain operator. We also comment on how the formalism can be used to probe the existence of edge states

  16. Inflammatory Pseudotumor Originating from the Right Ventricular Outflow Tract

    Directory of Open Access Journals (Sweden)

    Mohita Singh

    2016-01-01

    Full Text Available Introduction. Inflammatory pseudotumor is an uncommon entity, and its cardiac origin is exceedingly rare. Case History. A previously healthy 27-year-old man was found to have a systolic murmur during preemployment screening evaluation. A transthoracic echocardiogram revealed a 4 × 2.5 cm mass originating from the right ventricle (RV outflow tract extending into the aortic root. A computed tomography guided biopsy confirmed an IgG4-related inflammatory pseudotumor. Patient was started on oral prednisone with subsequent reduction in mass size. Conclusion. Cardiac inflammatory pseudotumors are markedly rare tumors that should be considered in the differential of intracardiac tumors which otherwise includes cardiac fibromas, myxomas, and sarcomas.

  17. Calculating Free Energies Using Average Force

    Science.gov (United States)

    Darve, Eric; Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    A new, general formula that connects the derivatives of the free energy along the selected, generalized coordinates of the system with the instantaneous force acting on these coordinates is derived. The instantaneous force is defined as the force acting on the coordinate of interest so that when it is subtracted from the equations of motion the acceleration along this coordinate is zero. The formula applies to simulations in which the selected coordinates are either unconstrained or constrained to fixed values. It is shown that in the latter case the formula reduces to the expression previously derived by den Otter and Briels. If simulations are carried out without constraining the coordinates of interest, the formula leads to a new method for calculating the free energy changes along these coordinates. This method is tested in two examples - rotation around the C-C bond of 1,2-dichloroethane immersed in water and transfer of fluoromethane across the water-hexane interface. The calculated free energies are compared with those obtained by two commonly used methods. One of them relies on determining the probability density function of finding the system at different values of the selected coordinate and the other requires calculating the average force at discrete locations along this coordinate in a series of constrained simulations. The free energies calculated by these three methods are in excellent agreement. The relative advantages of each method are discussed.

  18. SPITZER OBSERVATIONS OF BOW SHOCKS AND OUTFLOWS IN RCW 38

    Energy Technology Data Exchange (ETDEWEB)

    Winston, E. [ESA-ESTEC (SRE-SA), Keplerlaan 1, 2201 AZ Noordwijk ZH (Netherlands); Wolk, S. J.; Bourke, T. L.; Spitzbart, B. [Harvard Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Megeath, S. T. [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft Ave., Toledo, OH 43606 (United States); Gutermuth, R., E-mail: ewinston@rssd.esa.int [Five Colleges Astronomy Department, Smith College, Northampton, MA 01027 (United States)

    2012-01-10

    We report Spitzer observations of five newly identified bow shocks in the massive star-forming region RCW 38. Four are visible at Infrared Array Camera (IRAC) wavelengths, the fifth is only visible at 24 {mu}m. Chandra X-ray emission indicates that winds from the central O5.5 binary, IRS 2, have caused an outflow to the northeast and southwest of the central subcluster. The southern lobe of hot ionized gas is detected in X-rays; shocked gas and heated dust from the shock front are detected with Spitzer at 4.5 and 24 {mu}m. The northern outflow may have initiated the present generation of star formation, based on the filamentary distribution of the protostars in the central subcluster. Further, the bow-shock driving star, YSO 129, is photo-evaporating a pillar of gas and dust. No point sources are identified within this pillar at near- to mid-IR wavelengths. We also report on IRAC 3.6 and 5.8 {mu}m observations of the cluster DBS2003-124, northeast of RCW 38, where 33 candidate young stellar objects (YSOs) are identified. One star associated with the cluster drives a parsec-scale jet. Two Herbig-Haro objects associated with the jet are visible at IRAC and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. The jet extends over a distance of {approx}3 pc. Assuming a velocity of 100 km s{sup -1} for the jet material gives an age of 3 Multiplication-Sign 10{sup 4} yr, indicating that the star (and cluster) are likely to be very young, with a similar or possibly younger age than RCW 38, and that star formation is ongoing in the extended RCW 38 region.

  19. SPITZER OBSERVATIONS OF BOW SHOCKS AND OUTFLOWS IN RCW 38

    International Nuclear Information System (INIS)

    Winston, E.; Wolk, S. J.; Bourke, T. L.; Spitzbart, B.; Megeath, S. T.; Gutermuth, R.

    2012-01-01

    We report Spitzer observations of five newly identified bow shocks in the massive star-forming region RCW 38. Four are visible at Infrared Array Camera (IRAC) wavelengths, the fifth is only visible at 24 μm. Chandra X-ray emission indicates that winds from the central O5.5 binary, IRS 2, have caused an outflow to the northeast and southwest of the central subcluster. The southern lobe of hot ionized gas is detected in X-rays; shocked gas and heated dust from the shock front are detected with Spitzer at 4.5 and 24 μm. The northern outflow may have initiated the present generation of star formation, based on the filamentary distribution of the protostars in the central subcluster. Further, the bow-shock driving star, YSO 129, is photo-evaporating a pillar of gas and dust. No point sources are identified within this pillar at near- to mid-IR wavelengths. We also report on IRAC 3.6 and 5.8 μm observations of the cluster DBS2003-124, northeast of RCW 38, where 33 candidate young stellar objects (YSOs) are identified. One star associated with the cluster drives a parsec-scale jet. Two Herbig-Haro objects associated with the jet are visible at IRAC and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. The jet extends over a distance of ∼3 pc. Assuming a velocity of 100 km s –1 for the jet material gives an age of 3 × 10 4 yr, indicating that the star (and cluster) are likely to be very young, with a similar or possibly younger age than RCW 38, and that star formation is ongoing in the extended RCW 38 region.

  20. Modeling the outflow of liquid with initial supercritical parameters using the relaxation model for condensation

    Directory of Open Access Journals (Sweden)

    Lezhnin Sergey

    2017-01-01

    Full Text Available The two-temperature model of the outflow from a vessel with initial supercritical parameters of medium has been realized. The model uses thermodynamic non-equilibrium relaxation approach to describe phase transitions. Based on a new asymptotic model for computing the relaxation time, the outflow of water with supercritical initial pressure and super- and subcritical temperatures has been calculated.

  1. Coastal circulations driven by river outflow in a variable-density 1.5-layer model

    Digital Repository Service at National Institute of Oceanography (India)

    McCreary, J.P.; Zhang, S.; Shetye, S.R.

    A variable-density, 1.5-layer model is used to investigate the dynamics of the fresher-water plumes generated by river outflow. Solutions are found in a north-south channel, and the transport M sub(tau) and salinity S sub(tau) of the outflow...

  2. Radio Jets as Driving Mechanism of Fast Outflows: The HI View

    NARCIS (Netherlands)

    Morganti, Raffaella; Maccagni, Filippo; Oosterloo, Tom; Schulz, Robert; Santoro, Francesco

    2017-01-01

    The complex and multi-phase nature of gas outflows is one of the properties highlighted by the work in recent years on AGN-driven outflows. In particular, the cold gas is found to play a more important role than previously expected. Surprisingly, HI has been shown to be a good tracer of fast

  3. Financial Crisis, Capital Outflows, and Policy Responses: Examples from East Asia

    Science.gov (United States)

    Rajan, Ramkishen S.

    2007-01-01

    Financial crises seem to have become the norm rather than the exception since 1992. The author examines the impact of a crisis of confidence and resultant capital outflows from a small and open economy and the possible policy options in response to such outflows, using simple tools and definitions that will be familiar to any money and banking or…

  4. Misalignment of outflow axes in the proto-multiple systems in Perseus

    DEFF Research Database (Denmark)

    Lee, Katherine I.; Dunham, Michael M.; Myers, Philip C.

    2016-01-01

    We investigate the alignment between outflow axes in nine of the youngest binary/multiple systems in the Perseus Molecular Cloud. These systems have typical member spacing larger than 1000 au. For outflow identification, we use 12CO(2-1) and 12CO(3-2) data from a large survey with the Submillimet...

  5. Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows.

    Science.gov (United States)

    Governato, F; Brook, C; Mayer, L; Brooks, A; Rhee, G; Wadsley, J; Jonsson, P; Willman, B; Stinson, G; Quinn, T; Madau, P

    2010-01-14

    For almost two decades the properties of 'dwarf' galaxies have challenged the cold dark matter (CDM) model of galaxy formation. Most observed dwarf galaxies consist of a rotating stellar disk embedded in a massive dark-matter halo with a near-constant-density core. Models based on the dominance of CDM, however, invariably form galaxies with dense spheroidal stellar bulges and steep central dark-matter profiles, because low-angular-momentum baryons and dark matter sink to the centres of galaxies through accretion and repeated mergers. Processes that decrease the central density of CDM halos have been identified, but have not yet reconciled theory with observations of present-day dwarfs. This failure is potentially catastrophic for the CDM model, possibly requiring a different dark-matter particle candidate. Here we report hydrodynamical simulations (in a framework assuming the presence of CDM and a cosmological constant) in which the inhomogeneous interstellar medium is resolved. Strong outflows from supernovae remove low-angular-momentum gas, which inhibits the formation of bulges and decreases the dark-matter density to less than half of what it would otherwise be within the central kiloparsec. The analogues of dwarf galaxies-bulgeless and with shallow central dark-matter profiles-arise naturally in these simulations.

  6. Modeling investigation of the nutrient and phytoplankton variability in the Chesapeake Bay outflow plume

    Science.gov (United States)

    Jiang, Long; Xia, Meng

    2018-03-01

    The Chesapeake Bay outflow plume (CBOP) is the mixing zone between Chesapeake Bay and less eutrophic continental shelf waters. Variations in phytoplankton distribution in the CBOP are critical to the fish nursery habitat quality and ecosystem health; thus, an existing hydrodynamic-biogeochemical model for the bay and the adjacent coastal ocean was applied to understand the nutrient and phytoplankton variability in the plume and the dominant environmental drivers. The simulated nutrient and chlorophyll a distribution agreed well with field data and real-time satellite imagery. Based on the model calculation, the net dissolved inorganic nitrogen (DIN) and phosphorus (DIP) flux at the bay mouth was seaward and landward during 2003-2012, respectively. The CBOP was mostly nitrogen-limited because of the relatively low estuarine DIN export. The highest simulated phytoplankton biomass generally occurred in spring in the near field of the plume. Streamflow variations could regulate the estuarine residence time, and thus modulate nutrient export and phytoplankton biomass in the plume area; in comparison, changing nutrient loading with fixed streamflow had a less extensive impact, especially in the offshore and far-field regions. Correlation analyses and numerical experiments revealed that southerly winds on the shelf were effective in promoting the offshore plume expansion and phytoplankton accumulation. Climate change including precipitation and wind pattern shifts is likely to complicate the driving mechanisms of phytoplankton variability in the plume region.

  7. HIERARCHICAL FRAGMENTATION AND JET-LIKE OUTFLOWS IN IRDC G28.34+0.06: A GROWING MASSIVE PROTOSTAR CLUSTER

    International Nuclear Information System (INIS)

    Wang Ke; Wu Yuefang; Zhang Huawei; Zhang Qizhou

    2011-01-01

    We present Submillimeter Array (SMA) λ = 0.88 mm observations of an infrared dark cloud G28.34+0.06. Located in the quiescent southern part of the G28.34 cloud, the region of interest is a massive (>10 3 M sun ) molecular clump P1 with a luminosity of ∼10 3 L sun , where our previous SMA observations at 1.3 mm have revealed a string of five dust cores of 22-64 M sun along the 1 pc IR-dark filament. The cores are well aligned at a position angle (P.A.) of 48 deg. and regularly spaced at an average projected separation of 0.16 pc. The new high-resolution, high-sensitivity 0.88 mm image further resolves the five cores into 10 compact condensations of 1.4-10.6 M sun , with sizes of a few thousand AU. The spatial structure at clump (∼1 pc) and core (∼0.1 pc) scales indicates a hierarchical fragmentation. While the clump fragmentation is consistent with a cylindrical collapse, the observed fragment masses are much larger than the expected thermal Jeans masses. All the cores are driving CO (3-2) outflows up to 38 km s -1 , the majority of which are bipolar, jet-like outflows. The moderate luminosity of the P1 clump sets a limit on the mass of protostars of 3-7 M sun . Because of the large reservoir of dense molecular gas in the immediate medium and ongoing accretion as evident by the jet-like outflows, we speculate that P1 will grow and eventually form a massive star cluster. This study provides a first glimpse of massive, clustered star formation that currently undergoes through an intermediate-mass stage.

  8. Unveiling the molecular bipolar outflow of the peculiar red supergiant VY Canis Majoris

    Science.gov (United States)

    Shinnaga, Hiroko; Claussen, Mark J.; Lim, Jeremy; Dinh-van-Trung; Tsuboi, Masato

    2003-04-01

    We carried out polarimetric spectral-line imaging of the molecular outflow of the peculiar red supergiant VY Canis Majoris in SiO J=1-0 line in the ground vibrational state, which contains highly linearly-polarized velocity components, using the Very Large Array. We succeeded in unveiling the highly linearly polarized bipolar outflow for the first time at subarcsecond spatial resolution. The results clearly show that the direction of linear polarization of the brightest maser components is parallel to the outflow axis. The results strongly suggest that the linear polarization of the SiO maser is closely related to the outflow phenomena of the star. Furthermore, the results indicate that the linear polarization observed in the optical and infrared also occur due to the outflow phenomena.

  9. The Simbol-X Perspective on the Physics of Quasar Outflows

    Science.gov (United States)

    Giustini, M.; Cappi, M.; Vignali, C.; Palumbo, G. G. C.; Fiore, F.; Malaguti, G.

    2009-05-01

    There is increasing evidence that quasar outflows may play a key role in providing the feedback between AGN/QSOs and their surrounding (and feeding) media, in regulating the central supermassive black hole growth and the galaxy formation and, on larger scales, in shaping the growth of cosmic structures (see e.g. [1]). X-ray observations of quasar outflows are crucial to probe their innermost parts and assess the global energetics entrained in the outflow by studying its most extreme (in terms of velocity, ionization state, mass outflow rate) phases. Simbol-X-with its high effective area in the Fe K energy band and above-will allow the detection and the characterization of powerful outflows in bright, nearby AGN and notably also in moderately faint AGN, thus shedding light on feedback processes in these objects.

  10. Quantitation of uveoscleral outflow in normotensive and glaucomatous Beagles by 3H-labeled dextran

    International Nuclear Information System (INIS)

    Barrie, K.P.; Gum, G.G.; Samuelson, D.A.; Gelatt, K.N.

    1985-01-01

    In uveoscleral outflow, aqueous humor leaves the anterior chamber and passes caudally through the trabecular meshwork and the sclerociliary cleft to enter the supraciliary and suprachoroidal spaces. The fluid is then absorbed by choroidal and scleral circulations. Using 3 H-labeled dextran, uveoscleral outflow was quantitated in normotensive and glaucomatous Beagles under general anesthesia. The intrascleral plexus was isolated and 3 H-labeled dextran was injected into the anterior chamber. Intrascleral plexus contents were sampled every 5 minutes over a 30- to 60-minute period. The eyes were enucleated, sectioned, and prepared for scintillation counting. Uveoscleral outflow accounted for 15% and 3% of the total aqueous humor outflow in the normotensive dogs and in the advanced glaucomatous dogs, respectively. In the advanced glaucomatous Beagle, conventional and uveoscleral outflow pathways were reduced and contributed to the etiopathogenesis of glaucoma

  11. The average Indian female nose.

    Science.gov (United States)

    Patil, Surendra B; Kale, Satish M; Jaiswal, Sumeet; Khare, Nishant; Math, Mahantesh

    2011-12-01

    This study aimed to delineate the anthropometric measurements of the noses of young women of an Indian population and to compare them with the published ideals and average measurements for white women. This anthropometric survey included a volunteer sample of 100 young Indian women ages 18 to 35 years with Indian parents and no history of previous surgery or trauma to the nose. Standardized frontal, lateral, oblique, and basal photographs of the subjects' noses were taken, and 12 standard anthropometric measurements of the nose were determined. The results were compared with published standards for North American white women. In addition, nine nasal indices were calculated and compared with the standards for North American white women. The nose of Indian women differs significantly from the white nose. All the nasal measurements for the Indian women were found to be significantly different from those for North American white women. Seven of the nine nasal indices also differed significantly. Anthropometric analysis suggests differences between the Indian female nose and the North American white nose. Thus, a single aesthetic ideal is inadequate. Noses of Indian women are smaller and wider, with a less projected and rounded tip than the noses of white women. This study established the nasal anthropometric norms for nasal parameters, which will serve as a guide for cosmetic and reconstructive surgery in Indian women.

  12. Isotropic averaging for cell-dynamical-system simulation of spinodal ...

    Indian Academy of Sciences (India)

    HOT stands for higher order terms. Substituting the above in (1) we get. ¯ψ0 =ψ0 + 1. 2 n. ∑ i 1. ∂2ψ. ∂x2 i. 0. Á. ∂Ω x2 i ds. Á. ∂Ω. ds+HOT. In order to evaluate the integral in the above equation, we express the variables x1,x2, ...,xn on the surface of the 'sphere' in terms of the angles θ1,θ2, ...,θn 1, by x1 =ε cosθ1.

  13. Trajectory averaging for stochastic approximation MCMC algorithms

    KAUST Repository

    Liang, Faming

    2010-10-01

    The subject of stochastic approximation was founded by Robbins and Monro [Ann. Math. Statist. 22 (1951) 400-407]. After five decades of continual development, it has developed into an important area in systems control and optimization, and it has also served as a prototype for the development of adaptive algorithms for on-line estimation and control of stochastic systems. Recently, it has been used in statistics with Markov chain Monte Carlo for solving maximum likelihood estimation problems and for general simulation and optimizations. In this paper, we first show that the trajectory averaging estimator is asymptotically efficient for the stochastic approximation MCMC (SAMCMC) algorithm under mild conditions, and then apply this result to the stochastic approximation Monte Carlo algorithm [Liang, Liu and Carroll J. Amer. Statist. Assoc. 102 (2007) 305-320]. The application of the trajectory averaging estimator to other stochastic approximationMCMC algorithms, for example, a stochastic approximation MLE algorithm for missing data problems, is also considered in the paper. © Institute of Mathematical Statistics, 2010.

  14. THE ORION FINGERS: NEAR-IR SPECTRAL IMAGING OF AN EXPLOSIVE OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, Allison; Bally, John [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Ginsburg, Adam, E-mail: allison.youngblood@colorado.edu [ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany)

    2016-06-01

    We present near-IR (1.1–2.4 μ m) position–position–velocity cubes of the 500 year old Orion BN/KL explosive outflow with spatial resolution 1″ and spectral resolution 86 km s{sup −1}. We construct integrated intensity maps free of continuum sources of 15 H{sub 2} and [Fe ii] lines while preserving kinematic information of individual outflow features. Included in the detected H{sub 2} lines are the 1-0 S(1) and 1-0 Q(3) transitions, allowing extinction measurements across the outflow. Additionally, we present dereddened flux ratios for over two dozen outflow features to allow for the characterization of the true excitation conditions of the BN/KL outflow. All of the ratios show the dominance of the shock excitation of the H{sub 2} emission, although some features exhibit signs of fluorescent excitation from stellar radiation or J-type shocks. We also detect tracers of the PDR/ionization front north of the Trapezium stars in [O i] and [Fe ii] and analyze other observed outflows not associated with the BN/KL outflow.

  15. UNRAVELLING THE COMPLEX STRUCTURE OF AGN-DRIVEN OUTFLOWS. II. PHOTOIONIZATION AND ENERGETICS

    Energy Technology Data Exchange (ETDEWEB)

    Karouzos, Marios; Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Bae, Hyun-Jin, E-mail: woo@astro.snu.ac.kr [Department of Astronomy and Center for Galaxy EVolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2016-12-20

    Outflows have been shown to be prevalent in galaxies hosting luminous active galactic nuclei (AGNs); they present a physically plausible way to couple the AGN energy output with the interstellar medium of their hosts. Despite their prevalence, accurate characterization of these outflows has been challenging. In the second of a series of papers, we use Gemini Multi-Object Spectrograph integral field unit (IFU) data of six local ( z  < 0.1) and moderate-luminosity Type 2 AGNs to study the ionization properties and energetics of AGN-driven outflows. We find strong evidence connecting the extreme kinematics of the ionized gas to the AGN photoionization. The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as virial motions or rotation, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that 30 to 90% of the total mass and kinetic energy of the outflow is contained within the central kpc of the galaxy. The spatially integrated mass and kinetic energy of the gas entrained in the outflow correlate well with the AGN bolometric luminosity and results in energy conversion efficiencies between 0.01% and 1%. Intriguingly, we detect ubiquitous signs of ongoing circumnuclear star formation. Their small size, the centrally contained mass and energy, and the universally detected circumnuclear star formation cast doubts on the potency of these AGN-driven outflows as agents of galaxy-scale negative feedback.

  16. Multipoint analysis of the spatio-temporal coherence of dayside O+ outflows with Cluster

    Directory of Open Access Journals (Sweden)

    P. Puhl-Quinn

    2004-07-01

    Full Text Available The spatial distribution of ionospheric ion outflow from the dayside cusp/cleft has previously been studied in great detail with numerous satellite missions, but only statistically. Between July and November 2001, the orbit configuration of the Cluster multi-satellite system close to its perigee (4 Earth radii allows for delay times between spacecraft of about 4 and 35min in crossing the cusp/cleft. This enables for the first time to assess the spatial and temporal coherence of O+ ion outflow on time scales of the order of the satellite time lag. After presenting two contrasting events in detail, O+ velocities and outflow intensities from three spacecraft, available on 18 events, all with a similar orbit, have been cross-correlated to quantify the degree of coherence in the outflow. The main result from the analysis is that, although dayside outflows are a permanent feature, steady-state conditions are surprisingly never achieved. In particular, a significant variability is found for convection drift and local outflow intensities on small time scales. This variability of local intensities is not found to depend on the total strenghth of the outflow, which is much more stable and increases with the dynamic solar wind pressure.

  17. AGN feedback in action? - outflows and star formation in type 2 AGNs

    Science.gov (United States)

    Woo, Jong-Hak

    2017-01-01

    We present the statistical constraints on the ionized gas outflows and their connection to star formation, using a large sample of ~110,000 AGNs and star-forming galaxies at z dispersion of star forming galaxies can be entirely accounted by the gravitational potential of host galaxies, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. Second, the distribution in the [OIII] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the outflows are AGN-driven. Third, the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [OIII] profile. Interestingly, we find that the specific star formation of non-outflow AGNs is much lower than that of strong outflow AGNs, while the star formation rate of strong outflow AGNs is comparable to that of star forming galaxies. We interpret this trend as a delayed AGN feedback as it takes dynamical time for the outflows to suppress star formation in galactic scales.

  18. MULTIPLE FAST MOLECULAR OUTFLOWS IN THE PRE-PLANETARY NEBULA CRL 618

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chin-Fei; Huang, Po-Sheng [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Sahai, Raghvendra [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States); Sánchez Contreras, Carmen [Astrobiology Center (CSIC-INTA), ESAC Campus, E-28691 Villanueva de la Canada, Madrid (Spain); Tay, Jeremy Jian Hao [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2013-11-01

    CRL 618 is a well-studied pre-planetary nebula. It has multiple highly collimated optical lobes, fast molecular outflows along the optical lobes, and an extended molecular envelope that consists of a dense torus in the equator and a tenuous round halo. Here we present our observations of this source in CO J = 3-2 and HCN J = 4-3 obtained with the Submillimeter Array at up to ∼0.''3 resolutions. We spatially resolve the fast molecular outflow region previously detected in CO near the central star and find it to be composed of multiple outflows that have similar dynamical ages and are oriented along the different optical lobes. We also detect fast molecular outflows further away from the central star near the tips of the extended optical lobes and a pair of equatorial outflows inside the dense torus. We find that two episodes of bullet ejections in different directions are needed, one producing the fast molecular outflows near the central star and one producing the fast molecular outflows near the tips of the extended optical lobes. One possibility to launch these bullets is a magneto-rotational explosion of the stellar envelope.

  19. Transport pathways for Asian pollution outflow over the Pacific: Interannual and seasonal variations

    Science.gov (United States)

    Liu, Hongyu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.; Duncan, Bryan N.; Sachse, Glen W.

    2003-10-01

    The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February-April 2001). The model is used also to place the TRACE-P observations in an interannual (1994-2001) and seasonal context. The major process driving Asian pollution outflow in spring is frontal lifting ahead of southeastward-moving cold fronts (the leading edge of cold surges) and transport in the boundary layer behind the cold fronts. Orographic lifting over central and eastern China combines with the cold fronts to promote the transport of Chinese pollution to the free troposphere. Outflow of seasonal biomass burning in Southeast Asia during spring takes place mostly by deep convection but also by northeastward transport and frontal lifting, mixing with the anthropogenic outflow. Boundary layer outflow over the western Pacific is largely devoid of biomass burning influence. European and African (biomass burning) plumes in Asian outflow during TRACE-P were weak (pollution signal. Spring 2001 (La Niña) was characterized by unusually frequent cold surge events in the Asian Pacific rim and strong convection in Southeast Asia, leading to unusually strong boundary layer outflow of anthropogenic emissions and convective outflow of biomass burning emissions in the upper troposphere. The Asian outflow flux of CO to the Pacific is found to vary seasonally by a factor of 3-4 (maximum in March and minimum in summer). The March maximum results from frequent cold surge events and seasonal biomass burning emissions.

  20. A SEARCH FOR 95 GHz CLASS I METHANOL MASERS IN MOLECULAR OUTFLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Cong-Gui; Chen, Xi; Shen, Zhi-Qiang [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan RD, Shanghai 200030 (China); Xu, Ye; Ju, Bing-Gang, E-mail: cggan@shao.ac.cn [Key Laboratory of Radio Astronomy, Chinese Academy of Sciences (China)

    2013-01-20

    We have observed a sample of 288 molecular outflow sources including 123 high-mass and 165 low-mass sources in order to search for class I methanol masers at the 95 GHz transition and to investigate the relationship between outflow characteristics and class I methanol maser emission with the Purple Mountain Observatory 13.7 m radio telescope. Our survey detected 62 sources with 95 GHz methanol masers above a 3{sigma} detection limit, which includes 47 high-mass sources and 15 low-mass sources. Therefore, the detection rate is 38% for high-mass outflow sources and 9% for low-mass outflow sources, suggesting that class I methanol masers are relatively easily excited in high-mass sources. There are 37 newly detected 95 GHz methanol masers (including 27 high-mass and 10 low-mass sources), 19 of which are newly identified (i.e., first identification) class I methanol masers (including 13 high-mass and 6 low-mass sources). A statistical analysis of the distributions of maser detections with the outflow parameters reveals that the maser detection efficiency increases with the outflow properties (e.g., mass, momentum, kinetic energy, mechanical luminosity of outflows, etc.). Systematic investigations of the relationships between the intrinsic luminosity of methanol masers and the outflow properties (including mass, momentum, kinetic energy, bolometric luminosity, and mass-loss rate of the central stellar sources) indicate a positive correlation. This further supports the theory that class I methanol masers are collisionally pumped and associated with shocks when outflows interact with the surrounding ambient medium.

  1. [Surgical treatment of congenital obstruction of the left ventricular outflow tract].

    Science.gov (United States)

    Biocina, B; Sutlić, Z; Husedinović, I; Letica, D; Sokolić, J

    1993-01-01

    This report presents the classification and all types of left ventricular outflow tract obstructions. The possibilities of operative therapies are surveyed as well. Results of surgical treatment in 34 patients with obstruction to left ventricular outflow are shown. The majority of patients underwent operation under extracorporeal circulation (84.4%), while the rest were operated by means of the inflow occlusion technique (14.7%). The obtained results were compared with those from the literature. The importance of echocardiographic evaluation of location of the left ventricular outflow tract obstruction and the appropriate choice of a surgical technique according to the patient's age are emphasized.

  2. Fast Molecular Outflows in Luminous Galaxy Mergers: Evidence for Quasar Feedback from Herschel

    Science.gov (United States)

    Veilleux, S.; Melendez, M.; Sturm, E.; Garcia-Carpio, J.; Fischer, J.; Gonzalez-Alfonso, E.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.; hide

    2013-01-01

    We report the results from a systematic search for molecular (OH 119 micron) outflows with Herschel/PACS in a sample of 43 nearby (z 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. However, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  3. Estimation of future outflows of e-waste in India

    International Nuclear Information System (INIS)

    Dwivedy, Maheshwar; Mittal, R.K.

    2010-01-01

    The purpose of this study is to construct an approach and a methodology to estimate the future outflows of electronic waste (e-waste) in India. Consequently, the study utilizes a time-series multiple lifespan end-of-life model proposed by Peralta and Fontanos for estimating the current and future quantities of e-waste in India. The model estimates future e-waste generation quantities by modeling their usage and disposal. The present work considers two scenarios for the approximation of e-waste generation based on user preferences to store or to recycle the e-waste. This model will help formal recyclers in India to make strategic decisions in planning for appropriate recycling infrastructure and institutional capacity building. Also an extension of the model proposed by Peralta and Fontanos is developed with the objective of helping decision makers to conduct WEEE estimates under a variety of assumptions to suit their region of study. During 2007-2011, the total WEEE estimates will be around 2.5 million metric tons which include waste from personal computers (PC), television, refrigerators and washing machines. During the said period, the waste from PC will account for 30% of total units of WEEE generated.

  4. Physical Conditions in Ultra-fast Outflows in AGN

    Science.gov (United States)

    Kraemer, S. B.; Tombesi, F.; Bottorff, M. C.

    2018-01-01

    XMM-Newton and Suzaku spectra of Active Galactic Nuclei (AGN) have revealed highly ionized gas, in the form of absorption lines from H-like and He-like Fe. Some of these absorbers, ultra-fast outflows (UFOs), have radial velocities of up to 0.25c. We have undertaken a detailed photoionization study of high-ionization Fe absorbers, both UFOs and non-UFOs, in a sample of AGN observed by XMM-Newton. We find that the heating and cooling processes in UFOs are Compton-dominated, unlike the non-UFOs. Both types are characterized by force multipliers on the order of unity, which suggest that they cannot be radiatively accelerated in sub-Eddington AGN, unless they were much less ionized at their point of origin. However, such highly ionized gas can be accelerated via a magneto-hydrodynamic (MHD) wind. We explore this possibility by applying a cold MHD flow model to the UFO in the well-studied Seyfert galaxy, NGC 4151. We find that the UFO can be accelerated along magnetic streamlines anchored in the accretion disk. In the process, we have been able to constrain the magnetic field strength and the magnetic pressure in the UFO and have determined that the system is not in magnetic/gravitational equipartition. Open questions include the variability of the UFOs and the apparent lack of non-UFOs in UFO sources.

  5. Strong Stellar-driven Outflows Shape the Evolution of Galaxies at Cosmic Dawn

    Energy Technology Data Exchange (ETDEWEB)

    Fontanot, Fabio; De Lucia, Gabriella [INAF—Astronomical Observatory of Trieste, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Hirschmann, Michaela [Sorbonne Universités, UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, F-75014 Paris (France)

    2017-06-20

    We study galaxy mass assembly and cosmic star formation rate (SFR) at high redshift (z ≳ 4), by comparing data from multiwavelength surveys with predictions from the GAlaxy Evolution and Assembly (gaea) model. gaea implements a stellar feedback scheme partially based on cosmological hydrodynamical simulations, which features strong stellar-driven outflows and mass-dependent timescales for the re-accretion of ejected gas. In previous work, we have shown that this scheme is able to correctly reproduce the evolution of the galaxy stellar mass function (GSMF) up to z ∼ 3. We contrast model predictions with both rest-frame ultraviolet (UV) and optical luminosity functions (LFs), which are mostly sensitive to the SFR and stellar mass, respectively. We show that gaea is able to reproduce the shape and redshift evolution of both sets of LFs. We study the impact of dust on the predicted LFs, and we find that the required level of dust attenuation is in qualitative agreement with recent estimates based on the UV continuum slope. The consistency between data and model predictions holds for the redshift evolution of the physical quantities well beyond the redshift range considered for the calibration of the original model. In particular, we show that gaea is able to recover the evolution of the GSMF up to z ∼ 7 and the cosmic SFR density up to z ∼ 10.

  6. Strong Stellar-driven Outflows Shape the Evolution of Galaxies at Cosmic Dawn

    International Nuclear Information System (INIS)

    Fontanot, Fabio; De Lucia, Gabriella; Hirschmann, Michaela

    2017-01-01

    We study galaxy mass assembly and cosmic star formation rate (SFR) at high redshift (z ≳ 4), by comparing data from multiwavelength surveys with predictions from the GAlaxy Evolution and Assembly (gaea) model. gaea implements a stellar feedback scheme partially based on cosmological hydrodynamical simulations, which features strong stellar-driven outflows and mass-dependent timescales for the re-accretion of ejected gas. In previous work, we have shown that this scheme is able to correctly reproduce the evolution of the galaxy stellar mass function (GSMF) up to z ∼ 3. We contrast model predictions with both rest-frame ultraviolet (UV) and optical luminosity functions (LFs), which are mostly sensitive to the SFR and stellar mass, respectively. We show that gaea is able to reproduce the shape and redshift evolution of both sets of LFs. We study the impact of dust on the predicted LFs, and we find that the required level of dust attenuation is in qualitative agreement with recent estimates based on the UV continuum slope. The consistency between data and model predictions holds for the redshift evolution of the physical quantities well beyond the redshift range considered for the calibration of the original model. In particular, we show that gaea is able to recover the evolution of the GSMF up to z ∼ 7 and the cosmic SFR density up to z ∼ 10.

  7. Upwelling to Outflowing Oxygen Ions at Auroral Latitudes during Quiet Times: Exploiting a New Satellite Database

    Science.gov (United States)

    Redmon, Robert J.

    The mechanisms by which thermal O+ escapes from the top of the ionosphere and into the magnetosphere are not fully understood even with 30 years of active research. This thesis introduces a new database, builds a simulation framework around a thermospheric model and exploits these tools to gain new insights into the study of O+ ion outflows. A dynamic auroral boundary identification system is developed using Defense Meteorological Satellite Program (DMSP) spacecraft observations at 850 km to build a database characterizing the oxygen source region. This database resolves the ambiguity of the expansion and contraction of the auroral zone. Mining this new dataset, new understanding is revealed. We describe the statistical trajectory of the cleft ion fountain return flows over the polar cap as a function of activity and the orientation of the interplanetary magnetic field y-component. A substantial peak in upward moving O+ in the morning hours is discovered. Using published high altitude data we demonstrate that between 850 and 6000 km altitude, O+ is energized predominantly through transverse heating; and acceleration in this altitude region is relatively more important in the cusp than at midnight. We compare data with a thermospheric model to study the effects of solar irradiance, electron precipitation and neutral wind on the distribution of upward O+ at auroral latitudes. EUV irradiance is shown to play a dominant role in establishing a dawn-focused source population of upwelling O+ that is responsible for a pre-noon feature in escaping O+ fluxes. This feature has been corroborated by observations on platforms including the Dynamics Explorer 1 (DE-1), Polar, and Fast Auroral Snapshot SnapshoT (FAST) spacecraft. During quiet times our analysis shows that the neutral wind is more important than electron precipitation in establishing the dayside O+ upwelling distribution. Electron precipitation is found to play a relatively modest role in controlling dayside, and a

  8. Nonradial and nonpolytropic astrophysical outflows. X. Relativistic MHD rotating spine jets in Kerr metric

    Science.gov (United States)

    Chantry, L.; Cayatte, V.; Sauty, C.; Vlahakis, N.; Tsinganos, K.

    2018-04-01

    Context. High-resolution radio imaging of active galactic nuclei (AGN) has revealed that the jets of some sources present superluminal knots and transverse stratification. Recent observational projects, such as ALMA and γ-ray telescopes, such as HESS and HESS2 have provided new observational constraints on the central regions of rotating black holes in AGN, suggesting that there is an inner- or spine-jet surrounded by a disk wind. This relativistic spine-jet is likely to be composed of electron-positron pairs extracting energy from the black hole and will be explored by the future γ-ray telescope CTA. Aims: In this article we present an extension to and generalization of relativistic jets in Kerr metric of the Newtonian meridional self-similar mechanism. We aim at modeling the inner spine-jet of AGN as a relativistic light outflow emerging from a spherical corona surrounding a Kerr black hole and its inner accretion disk. Methods: The model is built by expanding the metric and the forces with colatitude to first order in the magnetic flux function. As a result of the expansion, all colatitudinal variations of the physical quantities are quantified by a unique parameter. Unlike previous models, effects of the light cylinder are not neglected. Results: Solutions with high Lorentz factors are obtained and provide spine-jet models up to the polar axis. As in previous publications, we calculate the magnetic collimation efficiency parameter, which measures the variation of the available energy across the field lines. This collimation efficiency is an integral part of the model, generalizing the classical magnetic rotator efficiency criterion to Kerr metric. We study the variation of the magnetic efficiency and acceleration with the spin of the black hole and show their high sensitivity to this integral. Conclusions: These new solutions model collimated or radial, relativistic or ultra-relativistic outflows in AGN or γ-ray bursts. In particular, we discuss the

  9. Bivariate copulas on the exponentially weighted moving average control chart

    Directory of Open Access Journals (Sweden)

    Sasigarn Kuvattana

    2016-10-01

    Full Text Available This paper proposes four types of copulas on the Exponentially Weighted Moving Average (EWMA control chart when observations are from an exponential distribution using a Monte Carlo simulation approach. The performance of the control chart is based on the Average Run Length (ARL which is compared for each copula. Copula functions for specifying dependence between random variables are used and measured by Kendall’s tau. The results show that the Normal copula can be used for almost all shifts.

  10. Averaging Bias Correction for Future IPDA Lidar Mission MERLIN

    Directory of Open Access Journals (Sweden)

    Tellier Yoann

    2018-01-01

    Full Text Available The CNES/DLR MERLIN satellite mission aims at measuring methane dry-air mixing ratio column (XCH4 and thus improving surface flux estimates. In order to get a 1% precision on XCH4 measurements, MERLIN signal processing assumes an averaging of data over 50 km. The induced biases due to the non-linear IPDA lidar equation are not compliant with accuracy requirements. This paper analyzes averaging biases issues and suggests correction algorithms tested on realistic simulated scenes.

  11. Averaging Bias Correction for Future IPDA Lidar Mission MERLIN

    Science.gov (United States)

    Tellier, Yoann; Pierangelo, Clémence; Wirth, Martin; Gibert, Fabien

    2018-04-01

    The CNES/DLR MERLIN satellite mission aims at measuring methane dry-air mixing ratio column (XCH4) and thus improving surface flux estimates. In order to get a 1% precision on XCH4 measurements, MERLIN signal processing assumes an averaging of data over 50 km. The induced biases due to the non-linear IPDA lidar equation are not compliant with accuracy requirements. This paper analyzes averaging biases issues and suggests correction algorithms tested on realistic simulated scenes.

  12. Recognition and treatment of outflow tract stenosis during and after endovascular exclusion for abdominal aortic aneurysm

    International Nuclear Information System (INIS)

    Lu Qingsheng; Jing Zaiping; Zhao Zhiqing; Bao Junmin; Zhao Jun; Feng Xiang; Feng Rui; Huang Sheng

    2003-01-01

    Objective: To study the cognition and treatment of outflow tract stenosis in and after endovascular exclusion for abdominal aortic aneurysm. Methods: From Mar 1997 to Oct 2002, in 136 patients undergoing abdominal aortic aneurysm endovascular exclusion, 8 patients had outflow tract stenosis during the operation, and 3 patients had outflow tract stenosis after operation. The stenosis of 5 patients occurred at the crotch of the graft-stent. PTA was done in 7 patients and stents were placed in stenotic segment in 2 patients. 2 patients were treated with crossover operation. Results: Following up 1 month to 2 years, all patients have no lower limbs ischemia. Conclusions: The diagnosis of outflow tract stenosis during and after abdominal endovascular exclusion for aortic aneurysm must be in time. The treatment should be according to the different causes of stenosis

  13. Low-energy ion outflow modulated by the solar wind energy input

    Science.gov (United States)

    Li, Kun; Wei, Yong; Andre, Mats; Eriksson, Anders; Haaland, Stein; Kronberg, Elena; Nilsson, Hans; Maes, Lukas

    2017-04-01

    Due to the spacecraft charging issue, it has been difficult to measure low-energy ions of ionospheric origin in the magnetosphere. A recent study taking advantage of the spacecraft electric potential has found that the previously 'hidden' low-energy ions is dominant in the magnetosphere. This comprehensive dataset of low-energy ions allows us to study the relationship between the ionospheric outflow and energy input from the solar wind (ɛ). In this study, we discuss the ratios of the solar wind energy input to the energy of the ionospheric outflow. We show that the ɛ controls the ionospheric outflow when the ɛ is high, while the ionospheric outflow does not systematically change with the ɛ when the ɛ is low.

  14. Dysregulated endocardial TGFβ signaling and mesenchymal transformation result in heart outflow tract septation failure.

    Science.gov (United States)

    Ma, Mancheong; Li, Peng; Shen, Hua; Estrada, Kristine D; Xu, Jian; Kumar, S Ram; Sucov, Henry M

    2016-01-01

    Heart outflow tract septation in mouse embryos carrying mutations in retinoic acid receptor genes fails with complete penetrance. In this mutant background, ectopic TGFβ signaling in the distal outflow tract is responsible for septation failure, but it was uncertain what tissue was responsive to ectopic TGFβ and why this response interfered with septation. By combining RAR gene mutation with tissue-specific Cre drivers and a conditional type II TGFβ receptor (Tgfbr2) allele, we determined that ectopic activation of TGFβ signaling in the endocardium is responsible for septation defects. Ectopic TGFβ signaling results in ectopic mesenchymal transformation of the endocardium and thereby in improperly constituted distal OFT cushions. Our analysis highlights the interactions between myocardium, endocardium, and neural crest cells in outflow tract morphogenesis, and demonstrates the requirement for proper TGFβ signaling in outflow tract cushion organization and septation. Copyright © 2015. Published by Elsevier Inc.

  15. A 3D view of the outflow in the Orion Molecular Cloud 1 (OMC-1)

    DEFF Research Database (Denmark)

    Nissen, H.D.; Cunningham, N.J.; Sherson, Maiken Gustafsson

    2012-01-01

    and proper motion data for near-IR emission of molecular hydrogen to obtain the first 3-dimensional (3D) structure of the OMC-1 outflow. Our work illustrates a new diagnostic tool for studies of star formation that will be exploited in the near future with the advent of high spatial resolution spectro...... Observatory, the Anglo-Australian Observatory and the Subaru Telescope. These data give the 3D velocity of ejecta yielding a 3D reconstruction of the outflows. This allows one to view the material from different vantage points in space giving considerable insight into the geometry. Our analysis indicates......The fast outflow emerging from a region associated with massive star formation in the Orion Molecular Cloud 1 (OMC-1), located behind the Orion Nebula, appears to have been set in motion by an explosive event. Here we study the structure and dynamics of outflows in OMC-1. We combine radial velocity...

  16. Averaging of nonlinearity-managed pulses

    International Nuclear Information System (INIS)

    Zharnitsky, Vadim; Pelinovsky, Dmitry

    2005-01-01

    We consider the nonlinear Schroedinger equation with the nonlinearity management which describes Bose-Einstein condensates under Feshbach resonance. By using an averaging theory, we derive the Hamiltonian averaged equation and compare it with other averaging methods developed for this problem. The averaged equation is used for analytical approximations of nonlinearity-managed solitons

  17. Study of Outflow and Molecular Lines from the Observations of BHR71 by The Herschel Key Program,``Dust, Ice, and Gas In Time" (DIGIT)

    Science.gov (United States)

    Yang, Yao-Lun; Green, Joel D.

    2014-07-01

    The infall and outflow processes initiated by the collapse a dense core are widely observed in Class 0 protostars, and significantly change the density and temperature structure of the prestellar core as well as the following disk and envelope evolution. Since the Class 0 protostars are usually embedded in the cold molecular envelope preventing them from being observed at visible or near-IR wavelengths, the spectral analyses of the far-IR spectra provide us a window to look through the envelope and constrain the physical properties of the envelope and the core. BHR71, a Class 0 embedded protostar, is located in an isolated neighborhood with a collimated bipolar outflow and shows a rich far-IR spectrum as observed in the DIGIT program (PI: Neal Evans) with Herschel. It has numerous molecular and atomic features that can constrain its physical properties and the density structure well. In this research, we developed a robust data reduction (Green et al. 2013a, b) and automatic line fitting package that ensures all of the molecular and atomic lines are extracted to the same standard and it can be easily used for any other protostars observed by Herschel as well. We found 44 and 28 emission lines in the central spaxel in the PACS and the SPIRE bands respectively, including CO, 13CO, OH, and H2O. The extended feature observed at low-J CO and several H2O lines are consistent to the outflow direction but less collimated and a heterogeneous environment is concluded from the rotational diagram analysis. A dust Monte Carlo radiative transfer simulation using RADMC-3D will reveal the embedded structure with a dust density profile of a flared disk and a spherical envelope with bipolar outflow cavity. We will use a line radiative transfer simulation for multiple species to constrain the chemical abundance distributions and their temperature profiles.With high sensitivity spatial resolved spectra and simulated internal structure analysis of BHR71 will provide a good test of

  18. The [O III] Profiles of Infrared-selected Active Galactic Nuclei: More Powerful Outflows in the Obscured Population

    Science.gov (United States)

    DiPompeo, M. A.; Hickox, R. C.; Carroll, C. M.; Runnoe, J. C.; Mullaney, J. R.; Fischer, T. C.

    2018-03-01

    We explore the kinematics of ionized gas via the [O III] λ5007 emission lines in active galactic nuclei (AGNs) selected on the basis of their mid-infrared (IR) emission, and split into obscured and unobscured populations based on their optical‑IR colors. After correcting for differences in redshift distributions, we provide composite spectra of spectroscopically and photometrically defined obscured/Type 2 and unobscured/Type 1 AGNs from 3500 to 7000 Å. The IR-selected obscured sources contain a mixture of narrow-lined Type 2 AGNs and intermediate sources that have broad Hα emission and significantly narrower Hβ. Using both [O III] luminosities and AGN luminosities derived from optical‑IR spectral energy distribution fitting, we find evidence for enhanced large-scale obscuration in the obscured sources. In matched bins of luminosity we find that the obscured population typically has broader, more blueshifted [O III] emission than in the unobscured sample, suggestive of more powerful AGN-driven outflows. This trend is not seen in spectroscopically classified samples, and is unlikely to be entirely explained by orientation effects. In addition, outflow velocities increase from small to moderate AGN E(B ‑ V) values, before flattening out (as traced by FWHM) and even decreasing (as traced by blueshift). While difficult to fully interpret in a single physical model, due to both the averaging over populations and the spatially averaged spectra, these results agree with previous findings that simple geometric unification models are insufficient for the IR-selected AGN population, and may fit into an evolutionary model for obscured and unobscured AGNs.

  19. Primary cardiac tumor presenting as left ventricular outflow tract obstruction and complex arrhythmia.

    Science.gov (United States)

    Fries, R; Achen, S; O'Brien, M T; Jackson, N D; Gordon, S

    2017-10-01

    An adult female mixed breed dog presented for recurrent collapsing episodes over several weeks. Holter evaluation revealed periods of sinus arrest and echocardiography identified a soft tissue mass with subsequent severe dynamic obstruction of the left ventricular outflow tract. The patient was euthanized five days after presentation for severe dyspnea. Necropsy revealed an irregular mass circumferentially lining the left ventricular outflow tract as well as multiple myocardial metastases. The final diagnosis was an undifferentiated pleomorphic endocardial sarcoma. Published by Elsevier B.V.

  20. ON THE ORIGIN OF THE MOLECULAR OUTFLOWS IN IRAS 16293–2422

    Energy Technology Data Exchange (ETDEWEB)

    Girart, Josep M.; Palau, Aina; Torrelles, José M. [Institut de Ciències de l' Espai, (CSIC-IEEC), Campus UAB, Facultat de Ciències, C5p 2, E-08193 Bellaterra, Catalonia (Spain); Estalella, Robert [Departament d' Astronomia i Meteorologia, Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès, Universitat de Barcelona, E-08028 Barcelona, Catalonia (Spain); Rao, Ramprasad, E-mail: girart@ice.cat [Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. Aohoku Pl., Hilo, HI 96720 (United States)

    2014-01-01

    We present CO 3-2, SiO 8-7, C{sup 34}S 7-6, and 878 μm dust continuum subarcsecond angular resolution observations with the Submillimeter Array (SMA) toward the IRAS 16293–2422 (I16293) multiple low-mass protostellar system. The C{sup 34}S emission traces the 878 μm dust continuum well, and in addition clearly shows a smooth velocity gradient along the major axis of component I16293A. CO shows emission at moderate high velocities arising from two bipolar outflows, which appear to be perpendicular with respect to each other. The high sensitivity and higher angular resolution of these observations allows us to pinpoint well the origin of these two outflows at the center of component I16293A. Interestingly, the most compact outflow appears to point toward I16293B. Our data show that the previously reported monopolar blueshifted CO outflow associated with component I16293B seems to be part of the compact outflow arising from component I16293A. In addition, the SiO emission is also tracing this compact outflow: on the one hand, the SiO emission appears to have a jet-like morphology along the southern redshifted lobe; on the other hand, the SiO emission associated with the blueshifted northern lobe traces a well-defined arc on the border of component I16293B facing I16293A. The blueshifted CO lobe of the compact outflow splits into two lobes around the position of this SiO arc. All these results lead us to propose that the compact outflow from component I16293A is impacting on the circumstellar gas around component I16293B, possibly being diverged as a consequence of the interaction.

  1. FEATURES OF OUTFLOW OF INTRAOCULAR LIQUID AFTER AN EKSIMERLAZER SKLEREKTOMY (PILOT STUDY)

    OpenAIRE

    E. A. Korchuganova; O. A. Rumyantseva; S. B. Gudkova

    2017-01-01

    Modern approaches to surgical glaucoma treatment is based on the safe and effective methods. In recent years, great attention is paid to the techniques of stimulating uveoscleral path outtake aqueous humor from the eye. Uveoscleral space in the extended outflow pathways is dominant and constitutes about 72%. Sclera is a field of the greatest interest, as the end stages of the outflow of aqueous humor via the uveoscleral path. The aim of the study was to investigate the influence of excimer la...

  2. THE SINS/zC-SINF SURVEY of z {approx} 2 GALAXY KINEMATICS: OUTFLOW PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Sarah F.; Genzel, Reinhard [Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States); Foerster-Schreiber, Natascha M.; Buschkamp, Peter; Davies, Ric; Eisenhauer, Frank; Kurk, Jaron; Lutz, Dieter [Max-Planck-Institut fuer extraterrestrische Physik (MPE), Giessenbachstr.1, D-85748 Garching (Germany); Griffin, Kristen Shapiro [Space Sciences Research Group, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); Mancini, Chiara; Renzini, Alvio [Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, Padova, I-35122 (Italy); Lilly, Simon J.; Carollo, C. Marcella; Peng, Yingjie [Institute of Astronomy, Department of Physics, Eidgenoessische Technische Hochschule, ETH Zuerich, CH-8093 (Switzerland); Bouche, Nicolas [Institut de Recherche en Astrophysique et Planetologie (IRAP), Universite de Toulouse, UPS-OMP, IRAP, 14, avenue Edouard Berlin, F-31400 Toulouse (France); Burkert, Andreas [Department fuer Physik, Universitaets-Sternwarte Ludwig-Maximilians-Universitaet (USM), Scheinerstr. 1, Muenchen, D-81679 (Germany); Cresci, Giovanni [Istituto Nazionale di AstrofisicaOsservatorio Astronomico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy); Genel, Shy [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hicks, Erin K. S. [Department of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195-1580 (United States); Naab, Thorsten, E-mail: sfnewman@berkeley.edu [Max-Planck Institute for Astrophysics, Karl Schwarzschildstrasse 1, D-85748 Garching (Germany); and others

    2012-12-10

    Using SINFONI H{alpha}, [N II], and [S II] AO data of 27 z {approx} 2 star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, we explore the dependence of outflow strength (via the broad flux fraction) on various galaxy parameters. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to at least the half-light radius ({approx}a few kpc). Decomposition of the [S II] doublet into broad and narrow components suggests that this outflowing gas probably has a density of {approx}10-100 cm{sup -3}, less than that of the star-forming gas (600 cm{sup -3}). There is a strong correlation of the H{alpha} broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 M{sub Sun} yr{sup -1} kpc{sup -2}. Above this threshold, we find that SFGs with log m{sub *} > 10 have similar or perhaps greater wind mass-loading factors ({eta} = M-dot{sub out}/SFR) and faster outflow velocities than lower mass SFGs, suggesting that the majority of outflowing gas at z {approx} 2 may derive from high-mass SFGs. The mass-loading factor is also correlated with the star formation rate (SFR), galaxy size, and inclination, such that smaller, more star-forming, and face-on galaxies launch more powerful outflows. We propose that the observed threshold for strong outflows and the observed mass loading of these winds can be explained by a simple model wherein break-out of winds is governed by pressure balance in the disk.

  3. MASS OUTFLOW IN THE SEYFERT 1 GALAXY NGC 5548

    International Nuclear Information System (INIS)

    Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Kaastra, J. S.; Arav, N.; Gabel, J. R.; Korista, K. T.

    2009-01-01

    We present a study of the intrinsic UV absorption and emission lines in an historically low-state spectrum of the Seyfert 1 galaxy NGC 5548, which we obtained in 2004 February at high spatial and spectral resolution with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. We isolate a component of emission with a width of 680 km s -1 that arises from an 'intermediate-line region' (ILR), similar to that we discovered in NGC 4151, at a distance of ∼1 pc from the central continuum source. From a detailed analysis of the five intrinsic absorption components in NGC 5548 and their behavior over a span of eight years, we present evidence that most of the UV absorbers only partially cover the ILR and do not cover an extended region of UV continuum emission, most likely from hot stars in the circumnuclear region. We also find that four of the UV absorbers are at much greater distances (greater than 70 pc) than the ILR, and none have sufficient N V or C IV column densities to be the ILR in absorption. At least a portion of the UV absorption component 3, at a radial velocity of -530 km s -1 , is likely responsible for most of the X-ray absorption, at a distance less than 7 pc from the central source. The fact that we see the ILR in absorption in NGC 4151 and not in NGC 5548 suggests that the ILR is located at a relatively large polar angle (∼45 deg.) with respect to the narrow-line region outflow axis.

  4. Regulation of Breathing and Autonomic Outflows by Chemoreceptors

    Science.gov (United States)

    Guyenet, Patrice G.

    2016-01-01

    Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes. PMID:25428853

  5. Saturated Pool Boiling in Vertical Annulus with Reduced Outflow Area

    International Nuclear Information System (INIS)

    Kang, Myeong Gie

    2012-01-01

    The mechanisms of pool boiling heat transfer have been studied extensively to design efficient heat transfer devices or to assure the integrity of safety related systems. However, knowledge on pool boiling heat transfer in a confined space is still quite limited. The confined nucleate boiling is an effective technique to enhance heat transfer. Improved heat transfer might be attributed to an increase in the heat transfer coefficient due to vaporization from the thin liquid film on the heating surface or increased bubble activity. According to Cornwell and Houston, the bubbles sliding on the heated surface agitate environmental liquid. In a confined space a kind of pulsating flow due to the bubbles is created and, as a result very active liquid agitation is generated. The increase in the intensity of liquid agitation results in heat transfer enhancement. Sometimes a deterioration of heat transfer appears at high heat fluxes for confined boiling. The cause of the deterioration is suggested as active bubble coalescence. Recently, Kang published inflow effects on pool boiling heat transfer in a vertical annulus with closed bottoms. Kang regulated the gap size at the upper regions of the annulus and identified that effects of the reduced gaps on heat transfer become evident as the heat flux increases. This kind of geometry is found in an in-pile test section. Since more detailed analysis is necessary, effects of the outflow area on nucleate pool boiling heat transfer are investigated in this study. Up to the author's knowledge, no previous results concerning to this effect have been published yet

  6. Self-similarity of higher-order moving averages

    Science.gov (United States)

    Arianos, Sergio; Carbone, Anna; Türk, Christian

    2011-10-01

    In this work, higher-order moving average polynomials are defined by straightforward generalization of the standard moving average. The self-similarity of the polynomials is analyzed for fractional Brownian series and quantified in terms of the Hurst exponent H by using the detrending moving average method. We prove that the exponent H of the fractional Brownian series and of the detrending moving average variance asymptotically agree for the first-order polynomial. Such asymptotic values are compared with the results obtained by the simulations. The higher-order polynomials correspond to trend estimates at shorter time scales as the degree of the polynomial increases. Importantly, the increase of polynomial degree does not require to change the moving average window. Thus trends at different time scales can be obtained on data sets with the same size. These polynomials could be interesting for those applications relying on trend estimates over different time horizons (financial markets) or on filtering at different frequencies (image analysis).

  7. Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

    Science.gov (United States)

    Rodriguez, J Alexis P; Kargel, Jeffrey S; Baker, Victor R; Gulick, Virginia C; Berman, Daniel C; Fairén, Alberto G; Linares, Rogelio; Zarroca, Mario; Yan, Jianguo; Miyamoto, Hideaki; Glines, Natalie

    2015-09-08

    Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

  8. Multiple monopolar outflows driven by massive protostars in IRAS 18162-2048

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-López, M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Girart, J. M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell 2, E-08193 Bellaterra, Catalunya (Spain); Curiel, S.; Fonfría, J. P. [Instituto de Astronomía, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-264, 04510 México, DF (Mexico); Zapata, L. A. [Centro de Radioastronomía y Astrofísica, UNAM, Apartado Postal 3-72, Morelia, Michoacán 58089 (Mexico); Qiu, K., E-mail: manferna@illinois.edu, E-mail: girart@ieec.cat [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-11-20

    In this article, we present Combined Array for Research in Millimeter-wave Astronomy (CARMA) 3.5 mm observations and SubMillimeter Array (SMA) 870 μm observations toward the high-mass star-forming region IRAS 18162-2048, which is the core of the HH 80/81/80N system. Molecular emission from HCN, HCO{sup +}, and SiO traces two molecular outflows (the so-called northeast and northwest outflows). These outflows have their origin in a region close to the position of MM2, a millimeter source known to harbor two protostars. For the first time we estimate the physical characteristics of these molecular outflows, which are similar to those of 10{sup 3}-5 × 10{sup 3} L {sub ☉} protostars, and suggest that MM2 harbors high-mass protostars. High-angular resolution CO observations show an additional outflow due southeast. Also for the first time, we identify its driving source, MM2(E), and see evidence of precession. All three outflows have a monopolar appearance, but we link the NW and SE lobes, and explain their asymmetric shape as being a consequence of possible deflection.

  9. GSTAR-SUR Modeling With Calendar Variations And Intervention To Forecast Outflow Of Currencies In Java Indonesia

    Science.gov (United States)

    Akbar, M. S.; Setiawan; Suhartono; Ruchjana, B. N.; Riyadi, M. A. A.

    2018-03-01

    Ordinary Least Squares (OLS) is general method to estimates Generalized Space Time Autoregressive (GSTAR) parameters. But in some cases, the residuals of GSTAR are correlated between location. If OLS is applied to this case, then the estimators are inefficient. Generalized Least Squares (GLS) is a method used in Seemingly Unrelated Regression (SUR) model. This method estimated parameters of some models with residuals between equations are correlated. Simulation study shows that GSTAR with GLS method for estimating parameters (GSTAR-SUR) is more efficient than GSTAR-OLS method. The purpose of this research is to apply GSTAR-SUR with calendar variation and intervention as exogenous variable (GSTARX-SUR) for forecast outflow of currency in Java, Indonesia. As a result, GSTARX-SUR provides better performance than GSTARX-OLS.

  10. Gas flows in the circumgalactic medium around simulated high-redshift galaxies

    Science.gov (United States)

    Mitchell, Peter D.; Blaizot, Jérémy; Devriendt, Julien; Kimm, Taysun; Michel-Dansac, Léo; Rosdahl, Joakim; Slyz, Adrianne

    2018-03-01

    We analyse the properties of circumgalactic gas around simulated galaxies in the redshift range z ≥ 3, utilizing a new sample of cosmological zoom simulations. These simulations are intended to be representative of the observed samples of Lyman α (Ly α) emitters recently obtained with the multi unit spectroscopic explorer (MUSE) instrument (halo masses ˜1010-1011 M⊙). We show that supernova feedback has a significant impact on both the inflowing and outflowing circumgalactic medium (CGM) by driving outflows, reducing diffuse inflow rates, and by increasing the neutral fraction of inflowing gas. By temporally stacking simulation outputs, we find that significant net mass exchange occurs between inflowing and outflowing phases: none of the phases are mass-conserving. In particular, we find that the mass in neutral outflowing hydrogen declines exponentially with radius as gas flows outwards from the halo centre. This is likely caused by a combination of both fountain-like cycling processes and gradual photoionization/collisional ionization of outflowing gas. Our simulations do not predict the presence of fast-moving neutral outflows in the CGM. Neutral outflows instead move with modest radial velocities (˜50 km s-1), and the majority of the kinetic energy is associated with tangential rather than radial motion.

  11. Multi-fluid simulations of the coupled solar wind-magnetosphere-ionsphere system

    Science.gov (United States)

    Lyon, J.

    2011-12-01

    This paper will review recent work done with the multi-fluid version of the Lyon-Fedder-Mobarry (MF-LFM) global MHD simulation code. We will concentrate on O+ outflow from the ionosphere and its importance for magnetosphere-ionosphere (MI) coupling and also the importance of ionospheric conditions in determining the outflow. While the predominant method of coupling between the magnetosphere and ionosphere is electrodynamic, it has become apparent the mass flows from the ionosphere into the magnetosphere can have profound effects on both systems. The earliest models to attempt to incorporate this effect used very crude clouds of plasma near the Earth. The earliest MF-LFM results showed that depending on the details of the outflow - where, how much, how fast - very different magnetospheric responses could be found. Two approaches to causally driven models for the outflow have been developed for use in global simulations, the Polar Wind Outflow Model (PWOM), started at the Univ. of Michigan, and the model used by Bill Lotko and co-workers at Dartmouth. We will give a quick review of this model which is based on the empirical relation between outflow fluence and Poynting flux discovered by Strangeway. An additional factor used in this model is the precipitating flux of electrons, which is presumed to correlate with the scale height of the upwelling ions. parameters such as outflow speed and density are constrained by the total fluence. The effects of the outflow depend on the speed. Slower outflow tends to land in the inner magnetosphere increasing the strength of the ring current. Higher speed flow out in the tail. Using this model, simulations have shown that solar wind dynamic pressure has a profound effect on the amount of fluence. The most striking result has been the simulation of magnetospheric sawtooth events. We will discuss future directions for this research, emphasizing the need for better physical models for the outflow process and its coupling to the

  12. How does the Red Sea outflow water interact with Gulf of Aden Eddies?

    Science.gov (United States)

    Ilıcak, Mehmet; Özgökmen, Tamay M.; Johns, William E.

    As the Red Sea overflow water (RSOW) enters the Gulf of Aden (GOA), it interacts with a sequence of nearly barotropic, mesoscale eddies originating in the Indian Ocean. To investigate how these eddies impact the dispersal and eastward transport of the RSOW toward the Indian Ocean, a high resolution 3D regional model is employed to explore systematically the interaction between the RSOW and mesoscale eddies. Two types of experiments are conducted. In the first set, we simulate the behavior of RSOW in the presence of an idealized cyclone and an idealized anticyclone. The second type of simulation involves nesting of the regional model (ROMS) within a data-assimilating global model (HYCOM), in which a sequence of mesoscale eddies entering the Gulf of Aden is realistically captured. This simulation is integrated for one year, and includes a simple representation of the seasonality of the RSOW. Bower et al. (2002) suggest that the Red Sea overflow might be a western boundary undercurrent. Consistent with these expectations, the idealized simulations show that the preferred pathway of the RSOW in the absence of eddies is along the coast of Somalia (southern continental shelf) as a western boundary undercurrent. Simultaneously, a cyclonic circulation is generated in the far western GOA due to vortex stretching by the descending outflow. The presence of a cyclone in the western GOA increases the peak RSOW transport, but the cyclone itself rapidly loses its coherence after interacting with the rough topography in the western GOA. The presence of an anticyclone tends to block the preferred boundary pathway and inhibits the eastward transport of the RSOW. The eddies also result in substantially increased mixing of the RSOW in the western GOA. On the basis of the more realistic ROMS experiment, it is found that the modeled RSOW leaves the western part of the Gulf of Aden in short episodic bursts with transports that are an order of magnitude greater than that associated with

  13. Object detection by correlation coefficients using azimuthally averaged reference projections.

    Science.gov (United States)

    Nicholson, William V

    2004-11-01

    A method of computing correlation coefficients for object detection that takes advantage of using azimuthally averaged reference projections is described and compared with two alternative methods-computing a cross-correlation function or a local correlation coefficient versus the azimuthally averaged reference projections. Two examples of an application from structural biology involving the detection of projection views of biological macromolecules in electron micrographs are discussed. It is found that a novel approach to computing a local correlation coefficient versus azimuthally averaged reference projections, using a rotational correlation coefficient, outperforms using a cross-correlation function and a local correlation coefficient in object detection from simulated images with a range of levels of simulated additive noise. The three approaches perform similarly in detecting macromolecular views in electron microscope images of a globular macrolecular complex (the ribosome). The rotational correlation coefficient outperforms the other methods in detection of keyhole limpet hemocyanin macromolecular views in electron micrographs.

  14. Structure of Ion Outflow in the Martian Magnetotail

    Science.gov (United States)

    McFadden, J. P.; Mitchell, D.; Luhmann, J. G.; Connerney, J. E. P.; Jakosky, B. M.

    2017-12-01

    The Suprathermal And Thermal Ion Composition (STATIC) sensor on the MAVEN spacecraft provides a detailed look at the structure of ion outflow in the Martian magnetotail including ion composition, energization, and flow. Mars' magnetotail contains a mixture of cold (multi-species ions, tailward-moving cold multi-species ions, suprathermal ions of a few tens of eV, warm (about 100 eV) proton populations, and heavy (primarily O+) pickup ions at energies from 1 to 10 keV which may display several simultaneous peaks in energy flux. The cold tailward-moving ions represent a significant fraction of the Martian ion loss, perhaps comparable to loses from molecular oxygen dissociation. The suprathermal tail that accompanies the cold ions varies greatly and provides clues to ion escape. The warm protons, on first examination, appear to be of sheath origin, displaying a similar energy distribution and accompanied by a tenuous warm population at M/Q=2 (which could be either solar wind alphas or molecular hydrogen ions of ionospheric origin). STATIC produces a weak ghost peak at M/Q=11-12 when observing molecular hydrogen ions, but not alphas, often allowing the instrument to distinguish the source of protons. Measurements show the warm protons are of ionospheric origin in the central tail and transition to sheath plasma in the umbra. Energetic (1-10 keV) pickup oxygen in the magnetotail is produced on the nightside, near the pole where the IMF convection electric field points toward the planet, the same hemisphere where sputtering occurs. When two spectral peaks are observed, these tailward-moving ions differ in direction by relatively small angles (about 20 degrees). These peaks can persist for tens of minutes indicating approximately time-stationary acceleration, and therefore acceleration in potential fields. Magnetotail structure and geometry can be inferred not only from the local magnetic field, but also from the measured electron distributions which indicate source

  15. Maximal venous outflow velocity: an index for iliac vein obstruction.

    Science.gov (United States)

    Jones, T Matthew; Cassada, David C; Heidel, R Eric; Grandas, Oscar G; Stevens, Scott L; Freeman, Michael B; Edmondson, James D; Goldman, Mitchell H

    2012-11-01

    Leg swelling is a common cause for vascular surgical evaluation, and iliocaval obstruction due to May-Thurner syndrome (MTS) can be difficult to diagnose. Physical examination and planar radiographic imaging give anatomic information but may miss the fundamental pathophysiology of MTS. Similarly, duplex ultrasonographic examination of the legs gives little information about central impedance of venous return above the inguinal ligament. We have modified the technique of duplex ultrasonography to evaluate the flow characteristics of the leg after tourniquet-induced venous engorgement, with the objective of revealing iliocaval obstruction characteristic of MTS. Twelve patients with signs and symptoms of MTS were compared with healthy control subjects for duplex-derived maximal venous outflow velocity (MVOV) after tourniquet-induced venous engorgement of the leg. The data for healthy control subjects were obtained from a previous study of asymptomatic volunteers using the same MVOV maneuvers. The tourniquet-induced venous engorgement mimics that caused during vigorous exercise. A right-to-left ratio of MVOV was generated for patient comparisons. Patients with clinical evidence of MTS had a mean right-to-left MVOV ratio of 2.0, asymptomatic control subjects had a mean ratio of 1.3, and MTS patients who had undergone endovascular treatment had a poststent mean ratio of 1.2 (P = 0.011). Interestingly, computed tomography and magnetic resonance imaging results, when available, were interpreted as positive in only 53% of the patients with MTS according to both our MVOV criteria and confirmatory venography. After intervention, the right-to-left MVOV ratio in the MTS patients was found to be reduced similar to asymptomatic control subjects, indicating a relief of central venous obstruction by stenting the compressive MTS anatomy. Duplex-derived MVOV measurements are helpful for detection of iliocaval venous obstruction, such as MTS. Right-to-left MVOV ratios and

  16. CLASSICAL T TAURI-LIKE OUTFLOW ACTIVITY IN THE BROWN DWARF MASS REGIME

    International Nuclear Information System (INIS)

    Whelan, E. T.; Ray, T. P.; Podio, L.; Bacciotti, F.; Randich, S.

    2009-01-01

    Over the last number of years, spectroscopic studies have strongly supported the assertion that protostellar accretion and outflow activity persist to the lowest masses. Indeed, previous to this work, the existence of three brown dwarf (BD) outflows had been confirmed by us. In this paper, we present the results of our latest investigation of BD outflow activity and report on the discovery of two new outflows. Observations to date have concentrated on studying the forbidden emission line (FEL) regions of young BDs and in all cases data have been collected using the UV-Visual Echelle Spectrometer (UVES) on the ESO Very Large Telescope. Offsets in the FEL regions are recovered using spectro-astrometry. Here, ISO-Oph 32 is shown to drive a blueshifted outflow with a radial velocity of 10-20 km s -1 and spectro-astrometric analysis constrains the position angle of this outflow to 240 0 ± 7 0 . The BD candidate, ISO-ChaI 217 is found to have a bipolar outflow bright in several key forbidden lines (V RAD = -20 km s -1 , +40 km s -1 ) and with a P.A. of 193 0 -209 0 . A striking feature of the ISO-ChaI 217 outflow is the strong asymmetry between the red- and blueshifted lobes. This asymmetry is revealed in the relative brightness of the two lobes (redshifted lobe is brighter), the factor of 2 difference in radial velocity (the redshifted lobe is faster) and the difference in the electron density (again higher in the red lobe). Such asymmetries are common in jets from low-mass protostars and the observation of a marked asymmetry at such a low mass ( sun ) supports the idea that BD outflow activity is scaled down from low-mass protostellar activity. Also note that although asymmetries are unexceptional, it is uncommon for the redshifted lobe to be the brightest as some obscuration by the accretion disk is assumed. This phenomenon has only been observed in one other source, the classical T Tauri (CTTS) star RW Aur. The physical mechanism responsible for the brightening of

  17. The average size of ordered binary subgraphs

    NARCIS (Netherlands)

    van Leeuwen, J.; Hartel, Pieter H.

    To analyse the demands made on the garbage collector in a graph reduction system, the change in size of an average graph is studied when an arbitrary edge is removed. In ordered binary trees the average number of deleted nodes as a result of cutting a single edge is equal to the average size of a

  18. Outflows, dusty cores, and a burst of star formation in the North America and Pelican nebulae

    Energy Technology Data Exchange (ETDEWEB)

    Bally, John [Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Ginsburg, Adam [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Munchen (Germany); Probst, Ron [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Reipurth, Bo [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii at Manoa, 640 North A' ohoku Place, Hilo, HI 96720 (United States); Shirley, Yancy L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Stringfellow, Guy S., E-mail: John.Bally@colorado.edu, E-mail: aginsburg@eso.org, E-mail: probst@noao.edu, E-mail: reipurth@ifa.hawaii.edu, E-mail: yshirley@as.arizona.edu, E-mail: Guy.Stringfellow@colorado.edu [Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 80309 (United States)

    2014-12-01

    We present observations of near-infrared 2.12 μm molecular hydrogen outflows emerging from 1.1 mm dust continuum clumps in the North America and Pelican Nebula (NAP) complex selected from the Bolocam Galactic Plane Survey (BGPS). Hundreds of individual shocks powered by over 50 outflows from young stars are identified, indicating that the dusty molecular clumps surrounding the NGC 7000/IC 5070/W80 H II region are among the most active sites of ongoing star formation in the solar vicinity. A spectacular X-shaped outflow, MHO 3400, emerges from a young star system embedded in a dense clump more than a parsec from the ionization front associated with the Pelican Nebula (IC 5070). Suspected to be a binary, the source drives a pair of outflows with orientations differing by 80°. Each flow exhibits S-shaped symmetry and multiple shocks indicating a pulsed and precessing jet. The 'Gulf of Mexico', located south of the North America Nebula (NGC 7000), contains a dense cluster of molecular hydrogen objects (MHOs), Herbig-Haro (HH) objects, and over 300 young stellar objects (YSOs), indicating a recent burst of star formation. The largest outflow detected thus far in the North America and Pelican Nebula complex, the 1.6 parsec long MHO 3417 flow, emerges from a 500 M {sub ☉} BGPS clump and may be powered by a forming massive star. Several prominent outflows such as MHO 3427 appear to be powered by highly embedded YSOs only visible at λ > 70 μm. An 'activity index' formed by dividing the number of shocks by the mass of the cloud containing their source stars is used to estimate the relative evolutionary states of Bolocam clumps. Outflows can be used as indicators of the evolutionary state of clumps detected in millimeter and submillimeter dust continuum surveys.

  19. An X-Ray/SDSS Sample: Observational Characterization of The Outflowing Gas

    Science.gov (United States)

    Perna, Michele; Brusa, M.; Lanzuisi, G.; Mignoli, M.

    2016-10-01

    Powerful ionised AGN-driven outflows, commonly detected both locally and at high redshift, are invoked to contribute to the co-evolution of SMBH and galaxies through feedback phenomena. Our recent works (Brusa+2015; 2016; Perna+2015a,b) have shown that the XMM-COSMOS targets with evidence of outflows collected so far ( 10 sources) appear to be associated with low X-ray kbol corrections (Lbol /LX ˜ 18), in spite of their spread in obscuration, in the locations on the SFR-Mstar diagram, in their radio emission. A higher statistical significance is required to validate a connection between outflow phenomena and a X-ray loudness. Moreover, in order to validate their binding nature to the galaxy fate, it is crucial to correctly determine the outflow energetics. This requires time consuming integral field spectroscopic (IFS) observations, which are, at present, mostly limited to high luminosity objectsThe study of SDSS data offers a complementary strategy to IFS efforts. I will present physical and demographic characterization of the AGN-galaxy system during the feedback phase obtained studying a sample of 500 X-ray/SDSS AGNs, at zdispersion) and X-ray properties (intrinsic X-ray luminosity, obscuration and X-ray kbol correction), to determine what drives ionised winds. Several diagnostic line ratios have been used to infer the physical properties of the ionised outflowing gas. The knowledge of these properties can reduce the actual uncertainties in the outflow energetics by a factor of ten, pointing to improve our understanding of the AGN outflow phenomenon and its impact on galaxy evolution.

  20. Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City

    Directory of Open Access Journals (Sweden)

    L. Molina

    2009-08-01

    Full Text Available We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2 kg/s of HCHO and 4.4 (4.0–5.0 kg/s of NO2 using the UV instrument and 3.66 (3.63–3.73 kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.

  1. PROPER MOTIONS OF YOUNG STELLAR OUTFLOWS IN THE MID-INFRARED WITH SPITZER (IRAC). I. THE NGC 1333 REGION

    International Nuclear Information System (INIS)

    Raga, A. C.; Noriega-Crespo, A.; Carey, S. J.; Arce, H. G.

    2013-01-01

    We use two 4.5 μm Spitzer (IRAC) maps of the NGC 1333 region taken over a ∼7 yr interval to determine proper motions of its associated outflows. This is a first successful attempt at obtaining proper motions of stellars' outflow from Spitzer observations. For the outflow formed by the Herbig-Haro objects HH7, 8, and 10, we find proper motions of ∼9-13 km s –1 , which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of eight outflows, ranging from ∼10 to 100 km s –1 . The derived proper motions show that out of these eight outflows, three have tangential velocities ≤20 km s –1 . This result shows that a large fraction of the observed outflows have low intrinsic velocities and that the low proper motions are not merely a projection effect.

  2. Reproducing multi-model ensemble average with Ensemble-averaged Reconstructed Forcings (ERF) in regional climate modeling

    Science.gov (United States)

    Erfanian, A.; Fomenko, L.; Wang, G.

    2016-12-01

    Multi-model ensemble (MME) average is considered the most reliable for simulating both present-day and future climates. It has been a primary reference for making conclusions in major coordinated studies i.e. IPCC Assessment Reports and CORDEX. The biases of individual models cancel out each other in MME average, enabling the ensemble mean to outperform individual members in simulating the mean climate. This enhancement however comes with tremendous computational cost, which is especially inhibiting for regional climate modeling as model uncertainties can originate from both RCMs and the driving GCMs. Here we propose the Ensemble-based Reconstructed Forcings (ERF) approach to regional climate modeling that achieves a similar level of bias reduction at a fraction of cost compared with the conventional MME approach. The new method constructs a single set of initial and boundary conditions (IBCs) by averaging the IBCs of multiple GCMs, and drives the RCM with this ensemble average of IBCs to conduct a single run. Using a regional climate model (RegCM4.3.4-CLM4.5), we tested the method over West Africa for multiple combination of (up to six) GCMs. Our results indicate that the performance of the ERF method is comparable to that of the MME average in simulating the mean climate. The bias reduction seen in ERF simulations is achieved by using more realistic IBCs in solving the system of equations underlying the RCM physics and dynamics. This endows the new method with a theoretical advantage in addition to reducing computational cost. The ERF output is an unaltered solution of the RCM as opposed to a climate state that might not be physically plausible due to the averaging of multiple solutions with the conventional MME approach. The ERF approach should be considered for use in major international efforts such as CORDEX. Key words: Multi-model ensemble, ensemble analysis, ERF, regional climate modeling

  3. Imaging the Aqueous Humor Outflow Pathway in Human Eyes by Three-dimensional Micro-computed Tomography (3D micro-CT)

    Energy Technology Data Exchange (ETDEWEB)

    C Hann; M Bentley; A Vercnocke; E Ritman; M Fautsch

    2011-12-31

    The site of outflow resistance leading to elevated intraocular pressure in primary open-angle glaucoma is believed to be located in the region of Schlemm's canal inner wall endothelium, its basement membrane and the adjacent juxtacanalicular tissue. Evidence also suggests collector channels and intrascleral vessels may have a role in intraocular pressure in both normal and glaucoma eyes. Traditional imaging modalities limit the ability to view both proximal and distal portions of the trabecular outflow pathway as a single unit. In this study, we examined the effectiveness of three-dimensional micro-computed tomography (3D micro-CT) as a potential method to view the trabecular outflow pathway. Two normal human eyes were used: one immersion fixed in 4% paraformaldehyde and one with anterior chamber perfusion at 10 mmHg followed by perfusion fixation in 4% paraformaldehyde/2% glutaraldehyde. Both eyes were postfixed in 1% osmium tetroxide and scanned with 3D micro-CT at 2 {mu}m or 5 {mu}m voxel resolution. In the immersion fixed eye, 24 collector channels were identified with an average orifice size of 27.5 {+-} 5 {mu}m. In comparison, the perfusion fixed eye had 29 collector channels with a mean orifice size of 40.5 {+-} 13 {mu}m. Collector channels were not evenly dispersed around the circumference of the eye. There was no significant difference in the length of Schlemm's canal in the immersed versus the perfused eye (33.2 versus 35.1 mm). Structures, locations and size measurements identified by 3D micro-CT were confirmed by correlative light microscopy. These findings confirm 3D micro-CT can be used effectively for the non-invasive examination of the trabecular meshwork, Schlemm's canal, collector channels and intrascleral vasculature that comprise the distal outflow pathway. This imaging modality will be useful for non-invasive study of the role of the trabecular outflow pathway as a whole unit.

  4. Aqueous Angiography: Real-Time and Physiologic Aqueous Humor Outflow Imaging.

    Directory of Open Access Journals (Sweden)

    Sindhu Saraswathy

    Full Text Available Trabecular meshwork (TM bypass surgeries attempt to enhance aqueous humor outflow (AHO to lower intraocular pressure (IOP. While TM bypass results are promising, inconsistent success is seen. One hypothesis for this variability rests upon segmental (non-360 degrees uniform AHO. We describe aqueous angiography as a real-time and physiologic AHO imaging technique in model eyes as a way to simulate live AHO imaging.Pig (n = 46 and human (n = 6 enucleated eyes were obtained, orientated based upon inferior oblique insertion, and pre-perfused with balanced salt solution via a Lewicky AC maintainer through a 1mm side-port. Fluorescein (2.5% was introduced intracamerally at 10 or 30 mm Hg. With an angiographer, infrared and fluorescent (486 nm images were acquired. Image processing allowed for collection of pixel information based on intensity or location for statistical analyses. Concurrent OCT was performed, and fixable fluorescent dextrans were introduced into the eye for histological analysis of angiographically active areas.Aqueous angiography yielded high quality images with segmental patterns (p<0.0001; Kruskal-Wallis test. No single quadrant was consistently identified as the primary quadrant of angiographic signal (p = 0.06-0.86; Kruskal-Wallis test. Regions of high proximal signal did not necessarily correlate with regions of high distal signal. Angiographically positive but not negative areas demonstrated intrascleral lumens on OCT images. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways.Aqueous angiography is a real-time and physiologic AHO imaging technique in model eyes.

  5. The mass-metallicity relations for gas and stars in star-forming galaxies: strong outflow versus variable IMF

    Science.gov (United States)

    Lian, Jianhui; Thomas, Daniel; Maraston, Claudia; Goddard, Daniel; Comparat, Johan; Gonzalez-Perez, Violeta; Ventura, Paolo

    2018-02-01

    We investigate the mass-metallicity relations for the gaseous (MZRgas) and stellar components (MZRstar) of local star-forming galaxies based on a representative sample from Sloan Digital Sky Survey Data Release 12. The mass-weighted average stellar metallicities are systematically lower than the gas metallicities. This difference in metallicity increases towards galaxies with lower masses and reaches 0.4-0.8 dex at 109 M⊙ (depending on the gas metallicity calibration). As a result, the MZRstar is much steeper than the MZRgas. The much lower metallicities in stars compared to the gas in low-mass galaxies imply dramatic metallicity evolution with suppressed metal enrichment at early times. The aim of this paper is to explain the observed large difference in gas and stellar metallicity and to infer the origin of the mass-metallicity relations. To this end we develop a galactic chemical evolution model accounting for star formation, gas inflow and outflow. By combining the observed mass-metallicity relation for both gas and stellar components to constrain the models, we find that only two scenarios are able to reproduce the observations. Either strong metal outflow or a steep initial mass function (IMF) slope at early epochs of galaxy evolution is needed. Based on these two scenarios, for the first time we successfully reproduce the observed MZRgas and MZRstar simultaneously, together with other independent observational constraints in the local Universe. Our model also naturally reproduces the flattening of the MZRgas at the high-mass end leaving the MZRstar intact, as seen in observational data.

  6. Ionized Gas Outflows from the MAGNUM Survey: NGC 1365 and NGC 4945

    Energy Technology Data Exchange (ETDEWEB)

    Venturi, Giacomo; Marconi, Alessandro [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino (Italy); Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Mingozzi, Matilde [Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); Carniani, Stefano [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge (United Kingdom); Kavli Institute for Cosmology, University of Cambridge, Cambridge (United Kingdom); Cresci, Giovanni [Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Risaliti, Guido [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino (Italy); Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy); Mannucci, Filippo, E-mail: gventuri@arcetri.astro.it [Osservatorio Astrofisico di Arcetri (INAF), Firenze (Italy)

    2017-11-24

    AGN feedback, acting through strong outflows accelerated in the nuclear region of AGN hosts, is invoked as a key ingredient for galaxy evolution by many models to explain the observed BH-galaxy scaling relations. Recently, some direct observational evidence of radiative mode feedback in action has been finally found in quasars at z >1.5. However, it is not possible to study outflows in quasars at those redshifts on small scales (≲100 pc), as spatial information is limited by angular resolution. This is instead feasible in nearby active galaxies, which are ideal laboratories to explore outflow structure and properties, as well as the effects of AGN on their host galaxies. In this proceeding we present preliminary results from the MAGNUM survey, which comprises nearby Seyfert galaxies observed with the integral field spectrograph VLT/MUSE. We focus on two sources, NGC 1365 and NGC 4945, that exhibit double conical outflows extending on distances >1 kpc. We disentangle the dominant contributions to ionization of the various gas components observed in the central ~5.3 kpc of NGC 1365. An attempt to infer outflow 3D structure in NGC 4945 is made via simple kinematic modeling, suggesting a hollow cone geometry.

  7. Differential Canalograms Detect Outflow Changes from Trabecular Micro-Bypass Stents and Ab Interno Trabeculectomy.

    Science.gov (United States)

    Parikh, Hardik A; Loewen, Ralitsa T; Roy, Pritha; Schuman, Joel S; Lathrop, Kira L; Loewen, Nils A

    2016-11-04

    Recently introduced microincisional glaucoma surgeries that enhance conventional outflow offer a favorable risk profile over traditional surgeries, but can be unpredictable. Two paramount challenges are the lack of an adequate training model for angle surgeries and the absence of an intraoperative quantification of surgical success. To address both, we developed an ex vivo training system and a differential, quantitative canalography method that uses slope-adjusted fluorescence intensities of two different chromophores to avoid quenching. We assessed outflow enhancement by trabecular micro-bypass (TMB) implantation or by ab interno trabeculectomy (AIT). In this porcine model, TMB resulted in an insignificant (p > 0.05) outflow increase of 13 ± 5%, 14 ± 8%, 9 ± 3%, and 24 ± 9% in the inferonasal, superonasal, superotemporal, and inferotemporal quadrant, respectively. AIT caused a 100 ± 50% (p = 0.002), 75 ± 28% (p = 0.002), 19 ± 8%, and 40 ± 21% increase in those quadrants. The direct gonioscopy and tactile feedback provided a surgical experience that was very similar to that in human patients. Despite the more narrow and discontinuous circumferential drainage elements in the pig with potential for underperformance or partial stent obstruction, unequivocal patterns of focal outflow enhancement by TMB were seen in this training model. AIT achieved extensive access to outflow pathways beyond the surgical site itself.

  8. Characterizing the origin and impact of the most extreme molecular outflows in the nearby universe

    Science.gov (United States)

    Gowardhan, Avani; Riechers, Dominik A.; Spoon, Henrik; Farrah, Duncan

    2018-01-01

    Observations over the last decade have revealed that feedback in the form of molecular gas outflows is ubiquitous in local ultra luminous infrared galaxies (ULIRGs). Such outflows can clear the nuclear environments of gas and dust, quench star formation and active galactic nuclei (AGN) growth, and they are a key step in the evolution of dust-obscured AGN to optically luminous quasars. We here present multi-spectral line observations of feedback in the two most powerful molecular gas outflows in the local universe. We spatially resolve the outflows to determine their kinematics and structure and find that they can drive out the molecular gas and quench star formation within ~ few Myr. Applying mid-IR diagnostics to constrain the relative contributions of AGN and nuclear starburst activity, we find that starburst activity plays a significant role in driving the outflow. We discuss the implications for future studies of feedback in the local universe and obscured AGN at high redshift, which is a key target population for JWST and ALMA over the next decade.

  9. Mass outflow in the nearby proto-planetary system, Beta Pictoris

    International Nuclear Information System (INIS)

    Bruhweiler, F.C.; Grady, C.A.; Kondo, Yoji

    1991-01-01

    Previous spectral studies of circumstallar dust around the nearby, candidate proto-planetary system, Beta Pictoris, has detected only infalling gas. The lack of detectable mass outflow has been critical in the interpretation of the origin of the circumstellar gas and in our understanding of the evolutionary status of the Beta Pictoris system. IUE high-dispersion spectra are presented which show, in addition to infall, the presence of mass outflow, with a maximum observed outflow velocity of -60 km/s, and a corresponding instantaneous outflow rate of 1.1 x 10 to the -14th solar mass/yr, or 1.1 x 10 to the -11th Jupiter mass/yr. This mass outflow rate and terminal velocity are comparable to the magnitudes of mass infall rates and terminal velocities observed from late 1986 through early 1988. The implications of these observations on our understanding of the mechanisms producing infall from the surrounding circumstellar disk are discussed, as are the implications for our understanding of the evolutionary status of the Beta Pic system. 23 refs

  10. Turbulent mixing layers in supersonic protostellar outflows, with application to DG Tauri

    Science.gov (United States)

    White, M. C.; Bicknell, G. V.; Sutherland, R. S.; Salmeron, R.; McGregor, P. J.

    2016-01-01

    Turbulent entrainment processes may play an important role in the outflows from young stellar objects at all stages of their evolution. In particular, lateral entrainment of ambient material by high-velocity, well-collimated protostellar jets may be the cause of the multiple emission-line velocity components observed in the microjet-scale outflows driven by classical T Tauri stars. Intermediate-velocity outflow components may be emitted by a turbulent, shock-excited mixing layer along the boundaries of the jet. We present a formalism for describing such a mixing layer based on Reynolds decomposition of quantities measuring fundamental properties of the gas. In this model, the molecular wind from large disc radii provides a continual supply of material for entrainment. We calculate the total stress profile in the mixing layer, which allows us to estimate the dissipation of turbulent energy, and hence the luminosity of the layer. We utilize MAPPINGS IV shock models to determine the fraction of total emission that occurs in [Fe II] 1.644 μm line emission in order to facilitate comparison to previous observations of the young stellar object DG Tauri. Our model accurately estimates the luminosity and changes in mass outflow rate of the intermediate-velocity component of the DG Tau approaching outflow. Therefore, we propose that this component represents a turbulent mixing layer surrounding the well-collimated jet in this object. Finally, we compare and contrast our model to previous work in the field.

  11. Brain Circuitry Supporting Multi-Organ Autonomic Outflow in Response to Nausea.

    Science.gov (United States)

    Sclocco, Roberta; Kim, Jieun; Garcia, Ronald G; Sheehan, James D; Beissner, Florian; Bianchi, Anna M; Cerutti, Sergio; Kuo, Braden; Barbieri, Riccardo; Napadow, Vitaly

    2016-02-01

    While autonomic outflow is an important co-factor of nausea physiology, central control of this outflow is poorly understood. We evaluated sympathetic (skin conductance level) and cardiovagal (high-frequency heart rate variability) modulation, collected synchronously with functional MRI (fMRI) data during nauseogenic visual stimulation aimed to induce vection in susceptible individuals. Autonomic data guided analysis of neuroimaging data, using a stimulus-based (analysis windows set by visual stimulation protocol) and percept-based (windows set by subjects' ratings) approach. Increased sympathetic and decreased parasympathetic modulation was associated with robust and anti-correlated brain activity in response to nausea. Specifically, greater autonomic response was associated with reduced fMRI signal in brain regions such as the insula, suggesting an inhibitory relationship with premotor brainstem nuclei. Interestingly, some sympathetic/parasympathetic specificity was noted. Activity in default mode network and visual motion areas was anti-correlated with parasympathetic outflow at peak nausea. In contrast, lateral prefrontal cortical activity was anti-correlated with sympathetic outflow during recovery, soon after cessation of nauseogenic stimulation. These results suggest divergent central autonomic control for sympathetic and parasympathetic response to nausea. Autonomic outflow and the central autonomic network underlying ANS response to nausea may be an important determinant of overall nausea intensity and, ultimately, a potential therapeutic target. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  12. Ionized Gas Outflows from the MAGNUM Survey: NGC 1365 and NGC 4945

    Directory of Open Access Journals (Sweden)

    Giacomo Venturi

    2017-11-01

    Full Text Available AGN feedback, acting through strong outflows accelerated in the nuclear region of AGN hosts, is invoked as a key ingredient for galaxy evolution by many models to explain the observed BH-galaxy scaling relations. Recently, some direct observational evidence of radiative mode feedback in action has been finally found in quasars at z >1.5. However, it is not possible to study outflows in quasars at those redshifts on small scales (≲100 pc, as spatial information is limited by angular resolution. This is instead feasible in nearby active galaxies, which are ideal laboratories to explore outflow structure and properties, as well as the effects of AGN on their host galaxies. In this proceeding we present preliminary results from the MAGNUM survey, which comprises nearby Seyfert galaxies observed with the integral field spectrograph VLT/MUSE. We focus on two sources, NGC 1365 and NGC 4945, that exhibit double conical outflows extending on distances >1 kpc. We disentangle the dominant contributions to ionization of the various gas components observed in the central ~5.3 kpc of NGC 1365. An attempt to infer outflow 3D structure in NGC 4945 is made via simple kinematic modeling, suggesting a hollow cone geometry.

  13. Soft X-ray Emission from Large-Scale Galactic Outflows in Seyfert Galaxies

    Science.gov (United States)

    Colbert, E. J. M.; Baum, S.; O'Dea, C.; Veilleux, S.

    1998-01-01

    Kiloparsec-scale soft X-ray nebulae extend along the galaxy minor axes in several Seyfert galaxies, including NGC 2992, NGC 4388 and NGC 5506. In these three galaxies, the extended X-ray emission observed in ROSAT HRI images has 0.2-2.4 keV X-ray luminosities of 0.4-3.5 x 10(40) erg s(-1) . The X-ray nebulae are roughly co-spatial with the large-scale radio emission, suggesting that both are produced by large-scale galactic outflows. Assuming pressure balance between the radio and X-ray plasmas, the X-ray filling factor is >~ 10(4) times as large as the radio plasma filling factor, suggesting that large-scale outflows in Seyfert galaxies are predominantly winds of thermal X-ray emitting gas. We favor an interpretation in which large-scale outflows originate as AGN-driven jets that entrain and heat gas on kpc scales as they make their way out of the galaxy. AGN- and starburst-driven winds are also possible explanations if the winds are oriented along the rotation axis of the galaxy disk. Since large-scale outflows are present in at least 50 percent of Seyfert galaxies, the soft X-ray emission from the outflowing gas may, in many cases, explain the ``soft excess" X-ray feature observed below 2 keV in X-ray spectra of many Seyfert 2 galaxies.

  14. Herbig-haro objects and mid-infrared outflows in the VELA C molecular cloud

    International Nuclear Information System (INIS)

    Zhang, Miaomiao; Wang, Hongchi; Henning, Thomas

    2014-01-01

    We have performed a deep [S II] λλ6717/6731 wide field Herbig-Haro (HH) object survey toward the Vela C molecular cloud with a sky coverage of about 2 deg 2 . In total, 18 new HH objects, HH 1090-1107, are discovered and the two previously known HH objects, HH 73-74, are also detected in our [S II] images. We also present an investigation of mid-infrared outflows in the Vela C molecular cloud using the Wide-field Infrared Survey Explorer images taken from AllWISE data release. Using the method suggested by Zhang and Wang, 11 extended green objects (EGOs) are identified to be the mid-infrared outflows, including 6 new mid-infrared outflows that have not been detected previously at other wavelengths and 5 mid-infrared counterparts of the HH objects detected in this work. Using the AllWISE Source Catalog and the source classification scheme suggested by Koenig et al., we have identified 56 young stellar object (YSO) candidates in the Vela C molecular cloud. The possible driving sources of the HH objects and EGOs are discussed based on the morphology of HH objects and EGOs and the locations of HH objects, EGOs and YSO candidates. Finally we associate 12 HH objects and 5 EGOs with 10 YSOs and YSO candidates. The median length of the outflows in Vela C is 0.35 pc and the outflows seem to be oriented randomly.

  15. A SYSTEMATIC SEARCH FOR MOLECULAR OUTFLOWS TOWARD CANDIDATE LOW-LUMINOSITY PROTOSTARS AND VERY LOW LUMINOSITY OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Kamber R.; Shirley, Yancy L. [Steward Observatory, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Dunham, Michael M. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

    2012-10-01

    We present a systematic single-dish search for molecular outflows toward a sample of nine candidate low-luminosity protostars and 30 candidate very low luminosity objects (VeLLOs; L{sub int} {<=} 0.1 L{sub Sun }). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D < 400 pc) star-forming regions. Each object was observed in {sup 12}CO and {sup 13}CO J = 2 {yields} 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30'' resolution. Using five-point grid maps, we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A-IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A-IRS3 outflow is detected but not re-mapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with the kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.

  16. A SYSTEMATIC SEARCH FOR MOLECULAR OUTFLOWS TOWARD CANDIDATE LOW-LUMINOSITY PROTOSTARS AND VERY LOW LUMINOSITY OBJECTS

    International Nuclear Information System (INIS)

    Schwarz, Kamber R.; Shirley, Yancy L.; Dunham, Michael M.

    2012-01-01

    We present a systematic single-dish search for molecular outflows toward a sample of nine candidate low-luminosity protostars and 30 candidate very low luminosity objects (VeLLOs; L int ≤ 0.1 L ☉ ). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D 12 CO and 13 CO J = 2 → 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30'' resolution. Using five-point grid maps, we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A-IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A-IRS3 outflow is detected but not re-mapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with the kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.

  17. Influence of surgical implantation angle of left ventricular assist device outflow graft and management of aortic valve opening on the risk of stroke in heart failure patients

    Science.gov (United States)

    Chivukula, V. Keshav; McGah, Patrick; Prisco, Anthony; Beckman, Jennifer; Mokadam, Nanush; Mahr, Claudius; Aliseda, Alberto

    2016-11-01

    Flow in the aortic vasculature may impact stroke risk in patients with left ventricular assist devices (LVAD) due to severely altered hemodynamics. Patient-specific 3D models of the aortic arch and great vessels were created with an LVAD outflow graft at 45, 60 and 90° from centerline of the ascending aorta, in order to understand the effect of surgical placement on hemodynamics and thrombotic risk. Intermittent aortic valve opening (once every five cardiac cycles) was simulated and the impact of this residual native output investigated for the potential to wash out stagnant flow in the aortic root region. Unsteady CFD simulations with patient-specific boundary conditions were performed. Particle tracking for 10 cardiac cycles was used to determine platelet residence times and shear stress histories. Thrombosis risk was assessed by a combination of Eulerian and Lagrangian metrics and a newly developed thrombogenic potential metric. Results show a strong influence of LVAD outflow graft angle on hemodynamics in the ascending aorta and consequently on stroke risk, with a highly positive impact of aortic valve opening, even at low frequencies. Optimization of LVAD implantation and management strategies based on patient-specific simulations to minimize stroke risk will be presented

  18. Averaging for solitons with nonlinearity management

    International Nuclear Information System (INIS)

    Pelinovsky, D.E.; Kevrekidis, P.G.; Frantzeskakis, D.J.

    2003-01-01

    We develop an averaging method for solitons of the nonlinear Schroedinger equation with a periodically varying nonlinearity coefficient, which is used to effectively describe solitons in Bose-Einstein condensates, in the context of the recently proposed technique of Feshbach resonance management. Using the derived local averaged equation, we study matter-wave bright and dark solitons and demonstrate a very good agreement between solutions of the averaged and full equations

  19. DSCOVR Magnetometer Level 2 One Minute Averages

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Interplanetary magnetic field observations collected from magnetometer on DSCOVR satellite - 1-minute average of Level 1 data

  20. DSCOVR Magnetometer Level 2 One Second Averages

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Interplanetary magnetic field observations collected from magnetometer on DSCOVR satellite - 1-second average of Level 1 data

  1. Spacetime averaging of exotic singularity universes

    International Nuclear Information System (INIS)

    Dabrowski, Mariusz P.

    2011-01-01

    Taking a spacetime average as a measure of the strength of singularities we show that big-rips (type I) are stronger than big-bangs. The former have infinite spacetime averages while the latter have them equal to zero. The sudden future singularities (type II) and w-singularities (type V) have finite spacetime averages. The finite scale factor (type III) singularities for some values of the parameters may have an infinite average and in that sense they may be considered stronger than big-bangs.

  2. NOAA Average Annual Salinity (3-Zone)

    Data.gov (United States)

    California Natural Resource Agency — The 3-Zone Average Annual Salinity Digital Geography is a digital spatial framework developed using geographic information system (GIS) technology. These salinity...

  3. Rapid growth of black holes accompanied with hot or warm outflows exposed to anisotropic super-Eddington radiation

    Science.gov (United States)

    Takeo, Eishun; Inayoshi, Kohei; Ohsuga, Ken; Takahashi, Hiroyuki R.; Mineshige, Shin

    2018-05-01

    We perform two-dimensional radiation hydrodynamical simulations of accretion flows on to a black hole (BH) with a mass of 103 ≤ MBH/ M⊙ ≲ 106 in order to study rapid growth of BHs in the early Universe. For spherically symmetric flows, hyper-Eddington accretion from outside the Bondi radius can occur unimpeded by radiation feedback when MBH ≳ 104 M⊙(n∞/105 cm - 3) - 1(T∞/104 K)3/2, where the density and temperature of ambient gas are initially set to n∞ = 105 cm-3 and T∞ = 104 K. Here, we study accretion flows exposed to anisotropic radiation from a nuclear accretion disc with a luminosity higher than the Eddington value (LEdd) due to collimation towards the bipolar directions. We find that, unlike the spherically symmetric case, even less massive BHs with MBH ionized regions expand towards the poles producing hot outflows with T ˜ 105 K. For more massive BHs with MBH ≳ 5 × 105 M⊙, intense inflows of neutral gas through the equator totally cover the central radiating region due to the non-radial gas motions. Because of efficient recombination by hydrogen, the entire flow settles in neutral and warm gas with T ≃ 8000 K. The BH is fed at a rate of ˜5 × 104LEdd/c2 (a half of the inflow rate from the Bondi radius). Moreover, radiation momentum absorbed by neutral hydrogen produces warm outflows towards the bipolar directions at ˜ 10 per cent of the BH feeding rate and with a velocity several times higher than the escaping value.

  4. From bipolar to quadrupolar - The collimation processes of the Cepheus A outflow

    Science.gov (United States)

    Torrelles, Jose M.; Verdes-Montenegro, Lourdes; Ho, Paul T. P.; Rodriguez, Luis F.; Canto, Jorge

    1993-01-01

    Results of new K-band observations of the (1, 1) and (2, 2) ammonia lines toward Cepheus A are reported. The lines are mapped with approximately 2 arcsec of angular resolution and 0.3 km/s of velocity resolution. A sensitivity of 10 mJy has been achieved. The observations reveal details of the spatial and kinematics structure of the ambient high-density gas. It is suggested that the interstellar high-density gas is diverting and redirecting the outflow in the sense that the quadrupolar structure of the molecular outflow is produced by the interaction with the ammonia condensationss, with Cep A-1 and Cep A-3 splitting in two halves, respectively the blue- and redshifted lobes of an east-west bipolar molecular outflow.

  5. Dependence of Ca outflow and depression of frog myocardium contraction on ryodipine concentration.

    Science.gov (United States)

    Narusevicius, E; Gendviliene, V; Macianskiene, R; Hmelj-Dunai, G; Velena, A; Duburs, G

    1988-02-01

    The effect of ryodipine on calcium outflow from tissues, on contraction force, the duration of action potentials and the relaxation phase time-constant in the contraction cycles of myocardial strips was studied using frog heart preparations. It was found that calcium outflow (delta Ca) as a function on ryodipine concentration can be represented as: (formula; see text) A linear correlation exists between Ca2+, contraction blocking and the shortening of the action potential in the presence of various ryodipine concentrations. Ryodipine (10(-5) mol/l) decreased the relaxation time-constant by about 20% as compared to controls. It was concluded that calcium outflow from myocardial tissues in response to ryodipine is due to blockade of calcium entry into the cells and their output through the Na+--Ca2+ exchange system. Frog heart myocardial contractions are essentially under the control of calcium entry through sarcolemmal calcium channels.

  6. Cloud Formation and Water Transport on Mars after Major Outflow Events

    Science.gov (United States)

    Santiago, D. L.; Colaprete, A.; Kreslavsky, M.; Kahre, M. A.; Asphaug, E.

    2012-01-01

    The triggering of a robust water cycle on Mars might have been caused by the gigantic flooding events evidenced by outflow channels. We use the Ames Mars General Circulation Model (MGCM) to test this hypothesis, studying how these presumably abrupt eruptions of water might have affected the climate of Mars in the past. We model where the water ultimately went as part of a transient atmospheric water cycle, to answer questions including: (1) Can sudden introductions of large amounts of water on the Martian surface lead to a new equilibrated water cycle? (2) What are the roles of water vapor and water ice clouds to sudden changes in the water cycle on Mars? (3) How are radiative feedbacks involved with this? (4) What is the ultimate fate of the outflow water? (5) Can we tie certain geological features to outflow water redistributed by the atmosphere?

  7. Systemic Embolization from an Unusual Intracardiac Mass in the Left Ventricular Outflow Tract

    Directory of Open Access Journals (Sweden)

    Kelechukwu U. Okoro

    2017-01-01

    Full Text Available Endocarditis can affect any endocardial surface; in the vast majority of cases, the cardiac valves are involved. It is exceedingly rare to develop infective endocarditis on the endocardium of the left ventricular outflow tract due to the high velocity of blood that traverses this area. Herein, we present a rare case of left ventricular outflow tract endocarditis that likely occurred secondary to damage to the aortic valve leaflets (from healed prior aortic valve endocarditis causing a high velocity aortic valve regurgitant jet that impinged upon the interventricular septum which damaged the endocardium and resulted in a fibrotic “jet lesion.” This fibrous jet lesion served as a nidus for bacterial proliferation and vegetation formation. The high shear stress (due to high blood flow velocity through the left ventricular outflow tract likely promoted the multiple embolic events observed in this case. Our patient was successfully treated with aortic valve replacement, vegetation resection, and antibiotics.

  8. Human cerebral venous outflow pathway depends on posture and central venous pressure

    DEFF Research Database (Denmark)

    Gisolf, J; van Lieshout, J J; van Heusden, K

    2004-01-01

    and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest......Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture...... and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position...

  9. The outflows accelerated by the magnetic fields and radiation force of accretion disks

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xinwu, E-mail: cxw@shao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 (China)

    2014-03-01

    The inner region of a luminous accretion disk is radiation-pressure-dominated. We estimate the surface temperature of a radiation-pressure-dominated accretion disk, Θ=c{sub s}{sup 2}/r{sup 2}Ω{sub K}{sup 2}≪(H/r){sup 2}, which is significantly lower than that of a gas-pressure-dominated disk, Θ ∼ (H/r){sup 2}. This means that the outflow can be launched magnetically from the photosphere of the radiation-pressure-dominated disk only if the effective potential barrier along the magnetic field line is extremely shallow or no potential barrier is present. For the latter case, the slow sonic point in the outflow will probably be in the disk, which leads to a slow circular dense flow above the disk. This implies that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated disk, which provides a natural explanation for the observational evidence that the relativistic jets are related to hot plasma in some X-ray binaries and active galactic nuclei. We investigate the outflows accelerated from the hot corona above the disk by the magnetic field and radiation force of the accretion disk. We find that with the help of the radiation force, the mass loss rate in the outflow is high, which leads to a slow outflow. This may be why the jets in radio-loud narrow-line Seyfert galaxies are in general mildly relativistic compared with those in blazars.

  10. DISCOVERY OF AN EXTREMELY WIDE-ANGLE BIPOLAR OUTFLOW IN AFGL 5142

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tie; Kim, Kee-Tae; Lee, Chang-Won; Cho, Se-Hyung [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wu, Yuefang [Department of Astronomy, Peking University, Beijing 100871 (China); Goldsmith, Paul F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Li, Di [National Astronomical Observatories, Chinese Academy of Science, A20 Datun Road, Chaoyang District, Beijing 100012 (China); Liu, Sheng-Yuan; Chen, Huei-Ru [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan (China); Tatematsu, Ken’ichi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Wang, Ke [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany); Lee, Jeong-Eun [School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Qin, Sheng-Li [Department of Astronomy, Yunnan University, and Key Laboratory of Astroparticle Physics of Yunnan Province, Kunming 650091 (China); Mardones, Diego, E-mail: liutiepku@gmail.com [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)

    2016-06-10

    Most bipolar outflows are associated with individual young stellar objects and have small opening angles. Here we report the discovery of an extremely wide-angle (∼180°) bipolar outflow (“EWBO”) in a cluster forming region AFGL 5142 from low-velocity emission of the HCN (3–2) and HCO{sup +} (3–2) lines. This bipolar outflow is along a north-west to south-east direction with a line of sight flow velocity of about 3 km s{sup −1} and is spatially connected to the high-velocity jet-like outflows. It seems to be a collection of low-velocity material entrained by the high-velocity outflows due to momentum feedback. The total ejected mass and mass loss rate due to both high-velocity jet-like outflows and the “EWBO” are ∼24.5 M {sub ⊙} and ∼1.7 × 10{sup −3} M {sub ⊙} yr{sup −1}, respectively. Global collapse of the clump is revealed by the “blue profile” in the HCO{sup +} (1–0) line. A hierarchical network of filaments was identified in NH{sub 3} (1, 1) emission. Clear velocity gradients of the order of 10 km s{sup −1} pc{sup −1} are found along filaments, indicating gas inflow along the filaments. The sum of the accretion rate along filaments and mass infall rate along the line of sight is ∼3.1 × 10{sup −3} M {sub ⊙} yr{sup −1}, which exceeds the total mass loss rate, indicating that the central cluster is probably still gaining mass. The central cluster is highly fragmented and 22 condensations are identified in 1.1 mm continuum emission. The fragmentation process seems to be determined by thermal pressure and turbulence. The magnetic field may not play an important role in fragmentation.

  11. Investigations of Short-Timescale Outflow Variability in Quasars of the Sloan Digital Sky Survey

    Science.gov (United States)

    Hemler, Zachary; Grier, Catherine; Brandt, William; Hall, Patrick; Schneider, Donald; Shen, Yue; Fernandez-Trincado, Jose; SDSS-RM Collaboration

    2018-01-01

    Quasar outflows are hypothesized to regulate the growth of a quasar's host galaxy and the supermassive black hole (SMBH) itself. Thus, understanding the physics of these outflows is imperative to understanding galactic evolution. The physical properties of these outflows, such as density, radial distance from the SMBH, and kinetic energy can be investigated by measuring both the strength and shape variability of broad absorption lines (BALs) in quasar spectra. However, the accuracy of physical properties calculated using BAL variability methods is limited by the time resolution of the observations. Recent spectral data from the Sloan Digital Sky Survey Reverberation Mapping program (SDSS-RM) provides a novel opportunity to investigate the short-term BAL variability of many quasars at many epochs. The SDSS-RM program took many epochs of spectra for a large sample of quasars over a period of several years, many of which exhibit BALs. The median rest-frame time resolution of these observations is roughly 2 days, in contrast to previous large-sample studies, which typically have time spacing on the order of hundred of days. We are using the SDSS-RM dataset to conduct a BAL variability study that will further constrain outflow properties and provide significant insights into the variability mechanisms of quasar outflows. We are searching for variability in BALs on timescales of less than 2 days among our sample of 22 quasars and determining whether this behavior is common among quasars. We are also investigating the general short-term (less than 10 days) variability characteristics of the entire sample. We will present preliminary results from this study and the possible implications to our understanding of quasar outflows.

  12. Outflows in the narrow-line region of bright Seyfert galaxies - I. GMOS-IFU data

    Science.gov (United States)

    Freitas, I. C.; Riffel, R. A.; Storchi-Bergmann, T.; Elvis, M.; Robinson, A.; Crenshaw, D. M.; Nagar, N. M.; Lena, D.; Schmitt, H. R.; Kraemer, S. B.

    2018-05-01

    We present two-dimensional maps of emission-line fluxes and kinematics, as well as of the stellar kinematics of the central few kpc of five bright nearby Seyfert galaxies - Mrk 6, Mrk 79, Mrk 348, Mrk 607, and Mrk 1058 - obtained from observations with the Gemini Multi-Object Spectrograph Integral Field Unit on the Gemini North Telescope. The data cover the inner 3.5 arcsec × 5.0 arcsec - corresponding to physical scales in the range 0.6 × 0.9-1.5 × 2.2 kpc2 - at a spatial resolution ranging from 110 to 280 pc with a spectral coverage of 4300-7100 Å and velocity resolution of ≈90 km s-1. The gas excitation is Seyfert like everywhere but show excitation gradients that are correlated with the gas kinematics, reddening and/or the gas density. The gas kinematics show in all cases two components: a rotation one similar to that observed in the stellar velocity field, and an outflow component. In the case of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas velocity dispersion is observed in association with the outflows according to two patterns: at the locations of the highest outflow velocities along the ionization axis or perpendicularly to it in a strip centred at the nucleus that we attribute to an equatorial outflow. Bipolar outflows are observed in Mrk 348 and Mrk 79, while in Mrk 1058 only the blueshifted part is clearly observed, while in cases of Mrk 6 and Mrk 607, the geometry of the outflow needs further constraints from modelling to be presented in a forthcoming study, where the mass flow rate and powers will also be obtained.

  13. The HST-pNFL program: Mapping the Fluorescent Emission of Galactic Outflows

    Science.gov (United States)

    Heckman, Timothy

    2017-08-01

    Galactic outflows associated with star formation are believed to play a crucial role in the evolution of galaxies and the IGM. Most of our knowledge about outflows has come from down-the-barrel UV absorption spectroscopy of star-forming galaxies. However, absorption-line data alone provide only indirect information about the radial structure of the gas flows, which introduces large systematic uncertainties in some of the most important quantities, such as the outflow rate, the mass loading factor, and the momentum, metal, and energy fluxes. Recent spectroscopic observations of star-forming galaxies with large (projected physical) apertures have revealed non-resonant (fluorescent) emission in the UV, e.g., FeII* and SiII*, that can be naturally produced by spatially extended emission from the same outflowing material traced in absorption. Encouraged by the most recent observations of FeII* emission by the SDSS-IV/eBOSS survey (Zhu et al. 2015), we propose a pilot program to use narrow-band filter UVIS F280N images to map the extended FeII* 2626 and 2613 fluorescent emission in a carefully-chosen sample of 4 starburst galaxies at z=0.065, and COS G130M to obtain down-the- barrel spectra for SiII absorption and SiII* emission. This HST pilot program can provide unique information about the spatial structure of galactic outflows and can potentially lead to a revolution in our understanding of outflow physics and its impact on galaxies and the IGM.

  14. Incision of the Jezero Crater Outflow Channel by Fluvial Sediment Transport

    Science.gov (United States)

    Holo, S.; Kite, E. S.

    2017-12-01

    Jezero crater, the top candidate landing site for the Mars 2020 rover, once possessed a lake that over-spilled and eroded a large outflow channel into the Eastern rim. The Western deltaic sediments that would be the primary science target of the rover record a history of lake level, which is modulated by the inflow and outflow channels. While formative discharges for the Western delta exist ( 500 m3/s), little work has been done to see if these flows are the same responsible for outflow channel incision. Other models of the Jezero outflow channel incision assume that a single rapid flood (incision timescales of weeks), with unknown initial hydraulic head and no discharge into the lake (e.g. from the inflow channels or the subsurface), incised an open channel with discharge modulated by flow over a weir. We present an alternate model where, due to an instability at the threshold of sediment motion, the incision of the outflow channel occurs in concert with lake filling. In particular, we assume a simplified lake-channel-valley system geometry and that the channel is hydraulically connected to the filling/draining crater lake. Bed load sediment transport and water discharge through the channel are quantified using the Meyer-Peter and Mueller relation and Manning's law respectively. Mass is conserved for both water and sediment as the lake level rises/falls and the channel incises. This model does not resolve backwater effects or concavity in the alluvial system, but it does capture the non-linear feedbacks between lake draining, erosion rate, channel flow rate, and slope relaxation. We identify controls on incision of the outflow channel and estimate the time scale of outflow channel formation through a simple dynamical model. We find that the observed 300m of channel erosion can be reproduced in decades to centuries of progressive bed load as the delta forming flows fill the lake. This corresponds to time scales on the order of or smaller than the time scale

  15. 40 CFR 76.11 - Emissions averaging.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Emissions averaging. 76.11 Section 76.11 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.11 Emissions averaging. (a) General...

  16. Determinants of College Grade Point Averages

    Science.gov (United States)

    Bailey, Paul Dean

    2012-01-01

    Chapter 2: The Role of Class Difficulty in College Grade Point Averages. Grade Point Averages (GPAs) are widely used as a measure of college students' ability. Low GPAs can remove a students from eligibility for scholarships, and even continued enrollment at a university. However, GPAs are determined not only by student ability but also by the…

  17. Near-ground ozone source attributions and outflow in central eastern China during MTX2006

    Science.gov (United States)

    Li, J.; Wang, Z.; Akimoto, H.; Yamaji, K.; Takigawa, M.; Pochanart, P.; Liu, Y.; Tanimoto, H.; Kanaya, Y.

    2008-12-01

    A 3-D regional chemical transport model, the Nested Air Quality Prediction Model System (NAQPMS), with an on-line tracer tagging module was used to study the source of the near-ground (pollutants, and it captured highly polluted and clean cases well. The simulated near-ground ozone level over CEC was 60-85 ppbv (parts per billion by volume), which was higher than values in Japan and over the North Pacific (20-50 ppbv). The simulated tagged tracer data indicated that the regional-scale transport of chemically produced ozone over other areas in CEC contributed to the greatest fraction (49%) of the near-ground mean ozone at Mt. Tai in June; in situ photochemistry contributed only 12%. Due to high anthropogenic and biomass burning emissions that occurred in the southern part of the CEC, the contribution to ground ozone levels from this area played the most important role (32.4 ppbv, 37.9% of total ozone) in the monthly mean ozone concentration at Mt. Tai; values reached 59 ppbv (62%) on 6-7 June 2006. The monthly mean horizontal distribution of chemically produced ozone from various ozone production regions indicated that photochemical reactions controlled the spatial distribution of O3 over CEC. The regional-scale transport of pollutants also played an important role in the spatial and temporal distribution of ozone over CEC. Chemically produced ozone from the southern part of the study region can be transported northeastwardly to the northern rim of CEC; the mean contribution was 5-10 ppbv, and it reached 25 ppbv during high ozone events. Studies of the outflow of CEC ozone and its precursors, as well as their influences and contributions to the ozone level over adjacent regions/countries, revealed that the contribution of CEC ozone to mean ozone mixing ratios over the Korean Peninsula and Japan was 5-15 ppbv, of which about half was due to the direct transport of ozone from CEC and half was produced locally by ozone precursors transported from CEC.

  18. Partial Averaged Navier-Stokes approach for cavitating flow

    International Nuclear Information System (INIS)

    Zhang, L; Zhang, Y N

    2015-01-01

    Partial Averaged Navier Stokes (PANS) is a numerical approach developed for studying practical engineering problems (e.g. cavitating flow inside hydroturbines) with a resonance cost and accuracy. One of the advantages of PANS is that it is suitable for any filter width, leading a bridging method from traditional Reynolds Averaged Navier-Stokes (RANS) to direct numerical simulations by choosing appropriate parameters. Comparing with RANS, the PANS model will inherit many physical nature from parent RANS but further resolve more scales of motion in great details, leading to PANS superior to RANS. As an important step for PANS approach, one need to identify appropriate physical filter-width control parameters e.g. ratios of unresolved-to-total kinetic energy and dissipation. In present paper, recent studies of cavitating flow based on PANS approach are introduced with a focus on the influences of filter-width control parameters on the simulation results

  19. Average contraction and synchronization of complex switched networks

    International Nuclear Information System (INIS)

    Wang Lei; Wang Qingguo

    2012-01-01

    This paper introduces an average contraction analysis for nonlinear switched systems and applies it to investigating the synchronization of complex networks of coupled systems with switching topology. For a general nonlinear system with a time-dependent switching law, a basic convergence result is presented according to average contraction analysis, and a special case where trajectories of a distributed switched system converge to a linear subspace is then investigated. Synchronization is viewed as the special case with all trajectories approaching the synchronization manifold, and is thus studied for complex networks of coupled oscillators with switching topology. It is shown that the synchronization of a complex switched network can be evaluated by the dynamics of an isolated node, the coupling strength and the time average of the smallest eigenvalue associated with the Laplacians of switching topology and the coupling fashion. Finally, numerical simulations illustrate the effectiveness of the proposed methods. (paper)

  20. SPECTROSCOPIC OBSERVATIONS OF CONTINUOUS OUTFLOWS AND PROPAGATING WAVES FROM NOAA 10942 WITH EXTREME ULTRAVIOLET IMAGING SPECTROMETER/HINODE

    International Nuclear Information System (INIS)

    Nishizuka, N.; Hara, H.

    2011-01-01

    We focused on 'sit-and-stare' observations of an outflow region at the edge of active region NOAA 10942 on 2007 February 20 obtained by the Extreme ultraviolet Imaging Spectrometer on board Hinode. We analyzed the data above the base of the outflow and found both continuous outflows and waves, which propagate from the base of the outflow. The spectra at the base of the outflow and at higher locations show different properties. The line profiles show blue-side asymmetry at the base of the outflow where nonthermal broadening becomes large because of fast upflows generated by heating events. On the other hand, at higher locations line profiles are symmetric and the intensity disturbances vary in phase with the velocity disturbances. The correlations between the intensity and velocity disturbances become noticeable at higher locations, so this indicates evidence of (at least locally) upward propagating slow-mode waves along the outflow. We also found a transient oscillation of different period in the wavelet spectrum. This indicates that a different wave is additionally observed during a limited period. High cadence spectroscopic observations revealed intermittent signatures of nonthermal velocities. Each of them seems to correspond to the base of the propagating disturbances. Furthermore, a jet was captured by the sit-and-stare observations across the slit. The similarity of line profiles of the outflow and the jet may indicate that the flows and waves originate in unresolved explosive events in the lower atmosphere of the corona.

  1. Foreign direct investment outflows in the forest products industry: the case of the United States and Japan

    Science.gov (United States)

    R.V. Nagubadi; D. Zhang

    2008-01-01

    This paper investigates the determinants of foreign direct investment (FDI) outflows from two major forest product importing countries: the U.S. and Japan. Exchange rate, per capita income, cost of capital, and cost of labour in host countries have significant impacts on the FDI outflows from these two countries. A complementary relationship is found between forest...

  2. Rotational averaging of multiphoton absorption cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Friese, Daniel H., E-mail: daniel.h.friese@uit.no; Beerepoot, Maarten T. P.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, University of Tromsø — The Arctic University of Norway, N-9037 Tromsø (Norway)

    2014-11-28

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  3. Sea Surface Temperature Average_SST_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea surface temperature collected via satellite imagery from http://www.esrl.noaa.gov/psd/data/gridded/data.noaa.ersst.html and averaged for each region using ArcGIS...

  4. Trajectory averaging for stochastic approximation MCMC algorithms

    KAUST Repository

    Liang, Faming

    2010-01-01

    to the stochastic approximation Monte Carlo algorithm [Liang, Liu and Carroll J. Amer. Statist. Assoc. 102 (2007) 305-320]. The application of the trajectory averaging estimator to other stochastic approximationMCMC algorithms, for example, a stochastic

  5. Should the average tax rate be marginalized?

    Czech Academy of Sciences Publication Activity Database

    Feldman, N. E.; Katuščák, Peter

    -, č. 304 (2006), s. 1-65 ISSN 1211-3298 Institutional research plan: CEZ:MSM0021620846 Keywords : tax * labor supply * average tax Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp304.pdf

  6. A practical guide to averaging functions

    CERN Document Server

    Beliakov, Gleb; Calvo Sánchez, Tomasa

    2016-01-01

    This book offers an easy-to-use and practice-oriented reference guide to mathematical averages. It presents different ways of aggregating input values given on a numerical scale, and of choosing and/or constructing aggregating functions for specific applications. Building on a previous monograph by Beliakov et al. published by Springer in 2007, it outlines new aggregation methods developed in the interim, with a special focus on the topic of averaging aggregation functions. It examines recent advances in the field, such as aggregation on lattices, penalty-based aggregation and weakly monotone averaging, and extends many of the already existing methods, such as: ordered weighted averaging (OWA), fuzzy integrals and mixture functions. A substantial mathematical background is not called for, as all the relevant mathematical notions are explained here and reported on together with a wealth of graphical illustrations of distinct families of aggregation functions. The authors mainly focus on practical applications ...

  7. MN Temperature Average (1961-1990) - Line

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data set depicts 30-year averages (1961-1990) of monthly and annual temperatures for Minnesota. Isolines and regions were created using kriging and...

  8. MN Temperature Average (1961-1990) - Polygon

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data set depicts 30-year averages (1961-1990) of monthly and annual temperatures for Minnesota. Isolines and regions were created using kriging and...

  9. Nonequilibrium statistical averages and thermo field dynamics

    International Nuclear Information System (INIS)

    Marinaro, A.; Scarpetta, Q.

    1984-01-01

    An extension of thermo field dynamics is proposed, which permits the computation of nonequilibrium statistical averages. The Brownian motion of a quantum oscillator is treated as an example. In conclusion it is pointed out that the procedure proposed to computation of time-dependent statistical average gives the correct two-point Green function for the damped oscillator. A simple extension can be used to compute two-point Green functions of free particles

  10. An approximate analytical approach to resampling averages

    DEFF Research Database (Denmark)

    Malzahn, Dorthe; Opper, M.

    2004-01-01

    Using a novel reformulation, we develop a framework to compute approximate resampling data averages analytically. The method avoids multiple retraining of statistical models on the samples. Our approach uses a combination of the replica "trick" of statistical physics and the TAP approach for appr...... for approximate Bayesian inference. We demonstrate our approach on regression with Gaussian processes. A comparison with averages obtained by Monte-Carlo sampling shows that our method achieves good accuracy....

  11. What's in the Wind? Determining the Properties of Outflowing Gas in Powerful Broad Absorption Line Quasars

    Science.gov (United States)

    Leighly, Karen

    2017-08-01

    A significant fraction of quasars exhibits blueshifted broadabsorption lines (BALs) in their rest-UV spectra, indicating powerfuloutflows emerging from the central engine. These outflows may removeangular momentum to enable black hole growth, enrich the intergalacticmedium with metals, and trigger quenching of star formation ingalaxies. Despite years of study, the physical conditions of theoutflowing gas are poorly understood. The handful of objects that havebeen subjected to detailed analysis are atypical and characterized byrelatively narrow lines where blending is unimportant. However,investigating more powerful BAL quasars will give us better insightinto the types of outflows much more likely to impact galaxyevolution.SimBAL is a novel spectral synthesis fitting method for BAL quasarsthat uses Bayesian model calibration to compare synthetic to observedspectra. With the model inputs of ionization parameter, columndensity, and covering fraction specified, the gas properties givingrise to the BAL features can be determined. We propose to applySimBAL to archival spectra of a sample of 14 luminous BAL quasars to characterize their bulk outflow properties as a function of velocityfor the first time. Our results will show the range of parameterstypical of powerful outflows, an essential step towards constrainingthe physics behind quasar winds and thus their impact on theirenvironments.

  12. X-ray evidence for ultra-fast outflows in Seyfert galaxies

    Science.gov (United States)

    Tombesi, Francesco; Braito, Valentina; Reeves, James; Cappi, Massimo; Dadina, Mauro

    2012-07-01

    X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts observed with XMM-Newton. Similar results are also obtained from a Suzaku analysis of 5 radio galaxies. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1}. The associated mechanical power is also high, in the range ˜10^{43}--10^{45} erg/s, which indicates that UFOs are capable to provide a significant contribution to the AGN cosmological feedback.

  13. Knowledge Outflows from Foreign Subsidiaries and the Tension Between Knowledge Creation and Knowledge Protection

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf

    2014-01-01

    This paper analyzes the MNC subsidiaries' trade-off between the need for knowledge creation and the need for knowledge protection, and relates it to the extent of knowledge outflows generated within the host location. Combining research in International Business with Social Theory, we build a con...

  14. THE NATURE AND FREQUENCY OF OUTFLOWS FROM STARS IN THE CENTRAL ORION NEBULA CLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    O’Dell, C. R. [Department of Physics and Astronomy, Vanderbilt University, Box 1807-B, Nashville, TN 37235 (United States); Ferland, G. J. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Henney, W. J. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apartado Postal 3-72, 58090 Morelia, Michoacán, México (Mexico); Peimbert, M. [Instituto de Astronomia, Universidad Nacional Autónoma de México, Apdo, Postal 70-264, 04510 México D. F., México (Mexico); García-Díaz, Ma. T. [Instituto de Astronomia, Universidad Nacional Autónoma de México, Km 103 Carretera Tijuana-Ensenada, 22860 Ensenada, B.C., México (Mexico); Rubin, Robert H., E-mail: cr.odell@vanderbilt.edu [NASA/Ames Research Center, Moffett Field, CA 94035-0001 (United States)

    2015-10-15

    Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database.

  15. Stent migration after right ventricular outflow tract stenting in the severe cyanotic Tetralogy of Fallot case

    Directory of Open Access Journals (Sweden)

    Tamaki Hayashi

    2017-01-01

    Full Text Available We report our experience with a stent migration after right ventricle outflow tract stenting and converted to patent ductus arteriosus stenting in Tetralogy of Fallot (TOF with severe infundibular stenosis. Finally, the patient achieved to TOF repair, and the migrated stent was removed without any complication.

  16. Launching Cosmic-Ray-Driven Outflows from The Magnetized Interstellar Medium

    Czech Academy of Sciences Publication Activity Database

    Girichidis, P.; Naab, T.; Walch, S.; Hanasz, M.; Mac Low, M.-M.; Ostriker, J.P.; Gatto, A.; Peters, T.; Wünsch, Richard; Glover, S.C.O.; Klessen, R.S.; Clark, P.C.; Baczynski, C.

    2016-01-01

    Roč. 816, č. 2 (2016), L19/1-L19/6 ISSN 2041-8205 R&D Projects: GA ČR GAP209/12/1795 Institutional support: RVO:67985815 Keywords : cosmic rays * diffusion * jets and outflows Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.522, year: 2016

  17. Liquid Acquisition Device Hydrogen Outflow Testing on the Cryogenic Propellant Storage and Transfer Engineering Design Unit

    Science.gov (United States)

    Zimmerli, Greg; Statham, Geoff; Garces, Rachel; Cartagena, Will

    2015-01-01

    As part of the NASA Cryogenic Propellant Storage and Transfer (CPST) Engineering Design Unit (EDU) testing with liquid hydrogen, screen-channel liquid acquisition devices (LADs) were tested during liquid hydrogen outflow from the EDU tank. A stainless steel screen mesh (325x2300 Dutch T will weave) was welded to a rectangular cross-section channel to form the basic LAD channel. Three LAD channels were tested, each having unique variations in the basic design. The LADs fed a common outflow sump at the aft end of the 151 cu. ft. volume aluminum tank, and included a curved section along the aft end and a straight section along the barrel section of the tank. Wet-dry sensors were mounted inside the LAD channels to detect when vapor was ingested into the LADs during outflow. The use of warm helium pressurant during liquid hydrogen outflow, supplied through a diffuser at the top of the tank, always led to early breakdown of the liquid column. When the tank was pressurized through an aft diffuser, resulting in cold helium in the ullage, LAD column hold-times as long as 60 minutes were achieved, which was the longest duration tested. The highest liquid column height at breakdown was 58 cm, which is 23 less than the isothermal bubble-point model value of 75 cm. This paper discusses details of the design, construction, operation and analysis of LAD test data from the CPST EDU liquid hydrogen test.

  18. Further studies of the role of dense molecular clouds around outflow sources

    International Nuclear Information System (INIS)

    Verdes-Montenegro, L.; Torrelles, J.M.; Rodriguez, L.F.; Anglada, G.; Lopez, R.

    1989-01-01

    The (J,K) = (1,1) and (2,2) ammonia inversion transitions toward six regions with active star formation and evidence of gas outflows have been observed. Ammonia emission has been detected and mapped in five of these regions: AFGL 5142, AFGL 5157, AFGL 6366S, HHL 73, and S140N. NH3 (2,2) emission was detected toward the peak of the NH3 (1,1) core of AFGL 5157 and S140N. A rotational temperature of T(R) (2,2;1,1) = about 16 K was estimated for the two regions. Two new H2O masers of intense emission, S(nu) greater or equal 40 Jy, were detected toward the ammonia cores of AFGL 5142 and AFGL 5157. It is clear that the dense NH3 gas is closely associated with the star formation activities, since the ammonia cores in all peak close to the centers of activity. In particular, the AFGL 5157 ammonia condensation coincides with the geometrical center of a bipolar molecular outflow, suggesting that the exciting source is embedded in the ammonia core. In contrast, the molecular outflow in the AFGL 6366S region is located at the southeast edge of the NH3 condensation, suggesting that the exciting source is outside the ammonia core and that the morphology of the outflow may be influenced by the interaction with the dense ambient gas. 52 refs

  19. Mediterranean Outflow Water dynamics during the past ~570 kyr : Regional and global implications

    NARCIS (Netherlands)

    Kaboth, Stefanie; de Boer, Bas; Bahr, André; Zeeden, Christiaan; Lourens, Lucas J.

    The Gulf of Cadiz constitutes a prime area to study teleconnections between the North Atlantic Ocean and climate change in the Mediterranean realm. In particular, the highly saline Mediterranean Outflow Water (MOW) is an important modulator of the North Atlantic salt budget on intermediate water

  20. A Massive X-ray Outflow From The Quasar PDS 456

    Science.gov (United States)

    Reeves, J. N.; O'Brien, P. T.; Ward, M. J.

    2003-01-01

    We report on XMM-Newton spectroscopic observations of the luminous, radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deep absorption trough (constituting 50% of the continuum) at energies above 7 keV in the quasar rest frame, which can be attributed to a series of blue-shifted K-shell absorption edges due to highly ionized iron. The higher resolution soft X-ray grating RGS spectrum exhibits a broad absorption line feature near 1 keV, which can be modeled by a blend of L-shell transitions from highly ionized iron (Fe XVII - XXIV). An extreme outflow velocity of approx. 50000 km/s is required to model the K and L shell iron absorption present in the XMM-Newton data. Overall, a large column density (N(sub H) = 5 x 10(exp 23)/sq cm) of highly ionized gas (log xi = 2.5) is required in PDS 456. A large mass outflow rate of approx. 10 solar mass/year (assuming a conservative outflow covering factor of 0.1 steradian) is derived, which is of the same order as the overall mass accretion rate in PDS 456. This represents a substantial fraction (approx. 10%) of the quasar energy budget, whilst the large column and outflow velocity place PDS 456 towards the extreme end of the broad absorption line quasar population.

  1. On the hydrogen neutral outflowing disks of B[e] supergiants

    Czech Academy of Sciences Publication Activity Database

    Kraus, Michaela; Borges Fernandes, M.; de Araújo, F. X.

    2007-01-01

    Roč. 463, č. 2 (2007), s. 627-634 ISSN 0004-6361 R&D Projects: GA ČR GA205/04/1267 Institutional research plan: CEZ:AV0Z10030501 Keywords : supergiants * winds * outflows Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.259, year: 2007

  2. Investigating the Influence of Technology Inflows on Technology Outflows in Open Innovation Processes : A Longitudinal Analysis

    NARCIS (Netherlands)

    Sikimic, U.; Chiesa, V.; Frattini, F.; Scalera, V.G.

    2016-01-01

    The open innovation (OI) paradigm emphasizes the importance of integrating inbound and outbound flows of technology to increase a firm's innovation performance. While the synergies between technology inflows and outflows have been discussed in conceptual OI articles, the majority of empirical

  3. Champagne flutes and brandy snifters: modelling protostellar outflow-cloud chemical interfaces

    Science.gov (United States)

    Rollins, R. P.; Rawlings, J. M. C.; Williams, D. A.; Redman, M. P.

    2014-10-01

    A rich variety of molecular species has now been observed towards hot cores in star-forming regions and in the interstellar medium. An increasing body of evidence from millimetre interferometers suggests that many of these form at the interfaces between protostellar outflows and their natal molecular clouds. However, current models have remained unable to explain the origin of the observational bias towards wide-angled `brandy snifter' shaped outflows over narrower `champagne flute' shapes in carbon monoxide imaging. Furthermore, these wide-angled systems exhibit unusually high abundances of the molecular ion HCO+. We present results from a chemodynamic model of such regions where a rich chemistry arises naturally as a result of turbulent mixing between cold, dense molecular gas and the hot, ionized outflow material. The injecta drives a rich and rapid ion-neutral chemistry in qualitative and quantitative agreement with the observations. The observational bias towards wide-angled outflows is explained naturally by the geometry-dependent ion injection rate causing rapid dissociation of CO in the younger systems.

  4. THE NATURE AND FREQUENCY OF OUTFLOWS FROM STARS IN THE CENTRAL ORION NEBULA CLUSTER

    International Nuclear Information System (INIS)

    O’Dell, C. R.; Ferland, G. J.; Henney, W. J.; Peimbert, M.; García-Díaz, Ma. T.; Rubin, Robert H.

    2015-01-01

    Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database

  5. Ammonia toroid aligned perpendicular to the HH 1 and HH 2 bipolar outflow

    International Nuclear Information System (INIS)

    Torrelles, J.M.; Canto, J.; Rodriguez, L.F.; Ho, P.T.P.; Moran, J.M.; Universidad Nacional Autonoma de Mexico, Mexico City)

    1985-01-01

    The ammonia emission from the region containing the Herbig-Haro objects 1 and 2, which mark the presence of a bipolar outflow, was mapped. The ammonia observations delineate an elongated structure aligned perpendicular to the bipolar outflow. This ammonia condensation is centered between HH 1 and HH 2 and coincides with the recently discovered central radio continuum source. This continuum source has no optical counterpart. The ammonia spectrum at the position of the continuum source shows a remarkable splitting. Based on the orientation of the bipolar outflow, which is known to be oriented nearly perpendicular to the line of sight, and on theoretical considerations, it is concluded that the ammonia source is part of a toroid, viewed edge-on, in slow expansion driven by the wind pressure of the central source. This toroid may be the focusing mechanism for the bipolar outflow. Searches for ammonia condensations in the vicinity of other HH objects may help localize the energy sources of these systems. 26 references

  6. The role of hemodynamics in the development of the outflow tract of the heart

    NARCIS (Netherlands)

    Loots, Erwin; Hillen, Berend; Veldman, Arthur E.P.

    The question whether, and if so to what extent, hemodynamic forces and mechanical stimuli do modulate the morphogenesis of the vascular system is a century-old problem. It is important especially in the outflow tract where a spiraling septum develops in and after a strong bend in the tube. Spiraling

  7. The response of relativistic outflowing gas to the inner accretion disk of a black hole.

    Science.gov (United States)

    Parker, Michael L; Pinto, Ciro; Fabian, Andrew C; Lohfink, Anne; Buisson, Douglas J K; Alston, William N; Kara, Erin; Cackett, Edward M; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C; Garcia, Javier; Harrison, Fiona A; King, Ashley L; Middleton, Matthew J; Miller, Jon M; Miniutti, Giovanni; Reynolds, Christopher S; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J; Wilkins, Daniel R; Zoghbi, Abderahmen

    2017-03-01

    The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different

  8. FEATURES OF OUTFLOW OF INTRAOCULAR LIQUID AFTER AN EKSIMERLAZER SKLEREKTOMY (PILOT STUDY

    Directory of Open Access Journals (Sweden)

    E. A. Korchuganova

    2017-01-01

    Full Text Available Modern approaches to surgical glaucoma treatment is based on the safe and effective methods. In recent years, great attention is paid to the techniques of stimulating uveoscleral path outtake aqueous humor from the eye. Uveoscleral space in the extended outflow pathways is dominant and constitutes about 72%. Sclera is a field of the greatest interest, as the end stages of the outflow of aqueous humor via the uveoscleral path. The aim of the study was to investigate the influence of excimer laser sclerectomy on the drainage function of the eye and development of a mathematical model based on the permeability of the sclera of the amount of laser ablation at a defined area of laser exposure and the level of IOP. Studies were conducted on 12 human cadaver eyes isolated person. The domestic excimer laser “MicroScan Vizum” with a wavelength of 193нм (0,193 µm was used for the thinning of sclera. In the experiment used a special computer program provided ablation of scleral tissue, the scleral bed forming a rectangular shape with a size 7,0x5,0 mm. the Depth of influence started from 100 microns to 600 microns in increments of 50 µn. The exposure was carried out at a constant perfusion pressure of 25 mm Hg After each impact was measured of the coefficient ease the outflow. A correlation was established between the factor and effective features, i.e., between the excimer laser deep sclerectomy (µm and ratio of lightness outflow (mm3/min/mm Hg.St. Thinning of the sclera leads to an improvement of its permeability and increasing the coefficient ease the outflow. A mathematical model, allowing to achieve the desired ratio of lightness outflow experiment by excimer laser sclerectomy was developed. The mathematical model has the form of the regression equation.The sclera is a promising object for further developments in the surgical treatment of glaucoma. Laser ablation of the sclera leads to an improvement of outflow via the uveoscleral path and

  9. SPATIALLY RESOLVED OBSERVATIONS OF THE BIPOLAR OPTICAL OUTFLOW FROM THE BROWN DWARF 2MASS J12073347–3932540

    International Nuclear Information System (INIS)

    Whelan, E. T.; Ray, T. P.; Comeron, F.; Bacciotti, F.; Kavanagh, P. J.

    2012-01-01

    Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M JUP BD 2MASS J12073347–3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [O I]λ6300 emission line. Follow-up observations consisting of spectra and [S II], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow position angle (P.A.) at ∼65°. The [O I]λ6300 emission line region is spatially resolved and the outflow is detected in the [S II] images. The detection is firstly in the form of an elongation of the point-spread function (PSF) along the direction of the outflow P.A. Four faint knot-like features (labeled A-D) are also observed to the southwest of 2MASS J12073347–3932540 along the same P.A. suggested by the spectra and the elongation in the PSF. Interestingly, D, the feature furthest from the source, is bow shaped with the apex pointing away from 2MASS J12073347–3932540. A color-color analysis allows us to conclude that at least feature D is part of the outflow under investigation while A is likely a star or galaxy. Follow-up observations are needed to confirm the origin of B and C. This is a first for a BD, as BD optical outflows have to date only been detected using spectro-astrometry. This result also demonstrates for the first time that BD outflows can be collimated and episodic.

  10. Long-Term Results of Stent Placement in Patients with Outflow Block After Living-Donor-Liver Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Fujimori, Masashi, E-mail: fujimorim@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Department of Radiology (Japan); Yamakado, Koichiro, E-mail: yamakado47@gmail.com; Takaki, Haruyuki, E-mail: takaki-h@clin.medic.mie-u.ac.jp [Hyogo College of Medicine, Department of Radiology (Japan); Nakatsuka, Atsuhiro, E-mail: nakatuka@clin.medic.mie-u.ac.jp; Uraki, Junji, E-mail: junji@clin.medic.mie-u.ac.jp; Yamanaka, Takashi, E-mail: t-yama@clin.medic.mie-u.ac.jp; Hasegawa, Takaaki, E-mail: hasegawat@clin.medic.mie-u.ac.jp; Sugino, Yuichi, E-mail: ysugino23@clin.medic.mie-u.ac.jp; Nakajima, Ken, E-mail: k-nakajima@clin.medic.mie-u.ac.jp; Matsushita, Naritaka, E-mail: n-matsushita@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Department of Radiology (Japan); Mizuno, Shugo, E-mail: mizunos@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Hepatobiliary Pancreatic and Transplant Surgery (Japan); Sakuma, Hajime, E-mail: sakuma.mie@gmail.com [Mie University School of Medicine, Department of Radiology (Japan); Isaji, Shuji, E-mail: isaji-s@clin.medic.mie-u.ac.jp [Mie University School of Medicine, Hepatobiliary Pancreatic and Transplant Surgery (Japan)

    2016-04-15

    PurposeTo evaluate long-term results of stent placement retrospectively in patients with outflow block after living-donor-liver transplantation (LDLT).Materials and MethodsFor this institutional review board approved retrospective study conducted during 2002–2012, stents were placed in outflow veins in 15 patients (11.3 %, 15/133) (12 men; 3 female) in whom outflow block developed after LDLT. Their mean age was 52.3 years ± 15.3 (SD) (range, 4–69 years). Venous stenosis with a pressure gradient ≥5 mmHg (outflow block) was observed in the inferior vena cava in seven patients, hepatic vein in seven patients, and both in one patient. Technical success, change in a pressure gradient and clinical manifestations, and complications were evaluated. Overall survival of 15 patients undergoing outflow block stenting was compared with that of 116 patients without outflow block after LDLT.ResultsStents were placed across the outflow block veins without complications, lowering the pressure gradient ≤ 3 mmHg in all patients (100 %, 15/15). Clinical manifestations improved in 11 patients (73.3 %, 11/15), and all were discharged from the hospital. However, they did not improve in the other 4 patients (26.7 %, 4/15) who died in the hospital 1.0–3.7 months after stenting (mean, 2.0 ± 1.2 months). No significant difference in 5-year survival rates was found between patients with and without outflow block after LDLT (61.1 vs. 72.2 %, p = .405).ConclusionStenting is a feasible, safe, and useful therapeutic option to resolve outflow block following LDLT, providing equal survival to that of patients without outflow block.

  11. Kinetic modeling of auroral ion outflows observed by the VISIONS sounding rocket

    Science.gov (United States)

    Albarran, R. M.; Zettergren, M. D.

    2017-12-01

    The VISIONS (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of the ion outflow below 1000km. Energetic ion data from the VISIONS polar cap boundary crossing show evidence of an ion "pressure cooker" effect whereby ions energized via transverse heating in the topside ionosphere travel upward and are impeded by a parallel potential structure at higher altitudes. VISIONS was also instrumented with an energetic neutral atom (ENA) detector which measured neutral particles ( 50-100 eV energy) presumably produced by charge-exchange with the energized outflowing ions. Hence, inferences about ion outflow may be made via remotely-sensing measurements of ENAs. This investigation focuses on modeling energetic outflowing ion distributions observed by VISIONS using a kinetic model. This kinetic model traces large numbers of individual particles, using a guiding-center approximation, in order to allow calculation of ion distribution functions and moments. For the present study we include mirror and parallel electric field forces, and a source of ion cyclotron resonance (ICR) wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady-state ion density altitude profile and Maxwellian velocity distribution characterizing the initial phase-space conditions for multiple particle trajectories. This project serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere and to improve data analysis methods for future sounding rocket and satellite missions.

  12. Discrete potentials guided radiofrequency ablation for idiopathic outflow tract ventricular arrhythmias.

    Science.gov (United States)

    Liu, Enzhao; Xu, Gang; Liu, Tong; Ye, Lan; Zhang, Qitong; Zhao, Yanshu; Li, Guangping

    2015-03-01

    Discrete potentials (DPs) have been recorded and targeted as the site of ablation of the outflow tract arrhythmias. The aim of the present study was to investigate the significance of DPs with respect to mapping and ablation for idiopathic outflow tract premature ventricular contractions (PVCs) or ventricular tachycardias (VTs). Seventeen consecutive patients with idiopathic right or left ventricular outflow tract PVCs/VTs who underwent radiofrequency catheter ablation were included. Intracardiac electrograms during the mapping and ablation were analysed. During sinus rhythm, sharp high-frequency DPs that displayed double or multiple components were recorded following or buried in the local ventricular electrograms in all of the 17 patients, peak amplitude 0.51 ± 0.21 mV. The same potential was recorded prior to the local ventricular potential of the PVCs/VTs. Spontaneous reversal of the relationship of the DPs to the local ventricular electrogram during the arrhythmias was noted. The DPs were related to a region of low voltage showed by intracardiac high-density contact mapping. At the sites with DPs, lower unipolar and bipolar ventricular voltage of sinus beats were noted compared with the adjacent regions without DPs (unipolar: 6.1 ± 1.8 vs. 8.3 ± 2.3 mV, P Discrete potentials were not present in seven controls. Discrete potentials and related low-voltage regions were common in idiopathic outflow tract ventricular arrhythmias. Discrete potential- and substrate-guided ablation strategy will help to reduce the recurrence of idiopathic outflow tract arrhythmias. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  13. Does an Intrinsic Magnetic Field Inhibit or Enhance Planetary Ionosphere Outflow and Loss?

    Science.gov (United States)

    Strangeway, R. J.; Russell, C. T.; Luhmann, J. G.; Moore, T. E.; Foster, J. C.; Barabash, S. V.; Nilsson, H.

    2017-12-01

    A characteristic feature of the planets Earth, Venus and Mars is the observation of the outflow of ionospheric ions, most notably oxygen. The oxygen ion outflow is frequently assumed to be a proxy for the loss of water from the planetary atmosphere. In terms of global outflow rates for the Earth the rate varies from 1025 to 1026 s-1, depending on geomagnetic activity. For both Venus and Mars global rates of the order 5x1024 s-1 have been reported. Venus and Mars do not have a large-scale intrinsic magnetic field, and there are several pathways for atmospheric and ionospheric loss. At Mars, because of its low gravity, neutral oxygen can escape through dissociative recombination. At Venus only processes related to the solar wind interaction with the planet such as sputtering and direct scavenging of the ionosphere by the solar wind can result in oxygen escape. At the Earth the intrinsic magnetic field forms a barrier to the solar wind, but reconnection of the Earth's magnetic field with the Interplanetary Magnetic Field allows solar wind energy and momentum to be transferred into the magnetosphere, resulting in ionospheric outflows. Observations of oxygen ions at the dayside magnetopause suggest that at least some of these ions escape. In terms of the evolution of planetary atmospheres how the solar-wind driven escape rates vary for magnetized versus umagnetized planets is also not clear. An enhanced solar wind dynamic pressure will increase escape from the unmagnetized planets, but it may also result in enhanced reconnection at the Earth, increasing outflow and loss rates for the Earth as well. Continued improvement in our understanding of the different pathways for ionospheric and atmospheric loss will allow us to determine how effective an intrinsic planetary field is in preserving a planetary atmosphere, or if we have to look for other explanations as to why the atmospheres of Venus and Mars have evolved to their desiccated state.

  14. Accurate phenotyping: Reconciling approaches through Bayesian model averaging.

    Directory of Open Access Journals (Sweden)

    Carla Chia-Ming Chen

    Full Text Available Genetic research into complex diseases is frequently hindered by a lack of clear biomarkers for phenotype ascertainment. Phenotypes for such diseases are often identified on the basis of clinically defined criteria; however such criteria may not be suitable for understanding the genetic composition of the diseases. Various statistical approaches have been proposed for phenotype definition; however our previous studies have shown that differences in phenotypes estimated using different approaches have substantial impact on subsequent analyses. Instead of obtaining results based upon a single model, we propose a new method, using Bayesian model averaging to overcome problems associated with phenotype definition. Although Bayesian model averaging has been used in other fields of research, this is the first study that uses Bayesian model averaging to reconcile phenotypes obtained using multiple models. We illustrate the new method by applying it to simulated genetic and phenotypic data for Kofendred personality disorder-an imaginary disease with several sub-types. Two separate statistical methods were used to identify clusters of individuals with distinct phenotypes: latent class analysis and grade of membership. Bayesian model averaging was then used to combine the two clusterings for the purpose of subsequent linkage analyses. We found that causative genetic loci for the disease produced higher LOD scores using model averaging than under either individual model separately. We attribute this improvement to consolidation of the cores of phenotype clusters identified using each individual method.

  15. Improved averaging for non-null interferometry

    Science.gov (United States)

    Fleig, Jon F.; Murphy, Paul E.

    2013-09-01

    Arithmetic averaging of interferometric phase measurements is a well-established method for reducing the effects of time varying disturbances, such as air turbulence and vibration. Calculating a map of the standard deviation for each pixel in the average map can provide a useful estimate of its variability. However, phase maps of complex and/or high density fringe fields frequently contain defects that severely impair the effectiveness of simple phase averaging and bias the variability estimate. These defects include large or small-area phase unwrapping artifacts, large alignment components, and voids that change in number, location, or size. Inclusion of a single phase map with a large area defect into the average is usually sufficient to spoil the entire result. Small-area phase unwrapping and void defects may not render the average map metrologically useless, but they pessimistically bias the variance estimate for the overwhelming majority of the data. We present an algorithm that obtains phase average and variance estimates that are robust against both large and small-area phase defects. It identifies and rejects phase maps containing large area voids or unwrapping artifacts. It also identifies and prunes the unreliable areas of otherwise useful phase maps, and removes the effect of alignment drift from the variance estimate. The algorithm has several run-time adjustable parameters to adjust the rejection criteria for bad data. However, a single nominal setting has been effective over a wide range of conditions. This enhanced averaging algorithm can be efficiently integrated with the phase map acquisition process to minimize the number of phase samples required to approach the practical noise floor of the metrology environment.

  16. High-altitude and high-latitude O+ and H+ outflows: the effect of finite electromagnetic turbulence wavelength

    Directory of Open Access Journals (Sweden)

    I. A. Barghouthi

    2007-11-01

    Full Text Available The energization of ions, due to interaction with electromagnetic turbulence (i.e. wave-particle interactions, has an important influence on H+ and O+ ions outflows in the polar region. The effects of altitude and velocity dependent wave-particle interaction on H+ and O+ ions outflows in the auroral region were investigated by using Monte Carlo method. The Monte Carlo simulation included the effects of altitude and velocity dependent wave-particle interaction, gravity, polarization electrostatic field, and divergence of auroral geomagnetic field within the simulation tube (1.2–10 earth radii, RE. As the ions are heated due to wave-particle interactions (i.e. ion interactions with electromagnetic turbulence and move to higher altitudes, the ion gyroradius ρi may become comparable to the electromagnetic turbulence wavelength λ⊥ and consequently (k⊥ρi becomes larger than unity. This turns the heating rate to be negligible and the motion of the ions is described by using Liouville theorem. The main conclusions are as follows: (1 the formation of H+ and O+ conics at lower altitudes and for all values of λ⊥; (2 O+ toroids appear at 3.72 RE, 2.76 RE and 2 RE, for λ⊥=100, 10, and 1 km, respectively; however, H+ toroids appear at 6.6 RE, 4.4 RE and 3 RE, for λ⊥=100, 10, and 1 km, respectively; and H+ and O+ ion toroids did not appear for the case λ⊥ goes to infinity, i.e. when the effect of velocity dependent wave-particle interaction was not included; (3 As λ⊥ decreases, H+ and O+ ion drift velocity decreases, H+ and O+ ion density increases, H+ and O+ ion perpendicular temperature and H+ and O+ ion parallel temperature decrease; (4 Finally, including the effect of finite electromagnetic turbulence wavelength, i.e. the effect of velocity dependent diffusion coefficient and consequently, the velocity dependent wave-particle interactions produce realistic H+ and O+ ion temperatures and H+ and O+ toroids, and this is, qualitatively

  17. Asynchronous Gossip for Averaging and Spectral Ranking

    Science.gov (United States)

    Borkar, Vivek S.; Makhijani, Rahul; Sundaresan, Rajesh

    2014-08-01

    We consider two variants of the classical gossip algorithm. The first variant is a version of asynchronous stochastic approximation. We highlight a fundamental difficulty associated with the classical asynchronous gossip scheme, viz., that it may not converge to a desired average, and suggest an alternative scheme based on reinforcement learning that has guaranteed convergence to the desired average. We then discuss a potential application to a wireless network setting with simultaneous link activation constraints. The second variant is a gossip algorithm for distributed computation of the Perron-Frobenius eigenvector of a nonnegative matrix. While the first variant draws upon a reinforcement learning algorithm for an average cost controlled Markov decision problem, the second variant draws upon a reinforcement learning algorithm for risk-sensitive control. We then discuss potential applications of the second variant to ranking schemes, reputation networks, and principal component analysis.

  18. Benchmarking statistical averaging of spectra with HULLAC

    Science.gov (United States)

    Klapisch, Marcel; Busquet, Michel

    2008-11-01

    Knowledge of radiative properties of hot plasmas is important for ICF, astrophysics, etc When mid-Z or high-Z elements are present, the spectra are so complex that one commonly uses statistically averaged description of atomic systems [1]. In a recent experiment on Fe[2], performed under controlled conditions, high resolution transmission spectra were obtained. The new version of HULLAC [3] allows the use of the same model with different levels of details/averaging. We will take advantage of this feature to check the effect of averaging with comparison with experiment. [1] A Bar-Shalom, J Oreg, and M Klapisch, J. Quant. Spectros. Rad. Transf. 65, 43 (2000). [2] J. E. Bailey, G. A. Rochau, C. A. Iglesias et al., Phys. Rev. Lett. 99, 265002-4 (2007). [3]. M. Klapisch, M. Busquet, and A. Bar-Shalom, AIP Conference Proceedings 926, 206-15 (2007).

  19. An approach to averaging digitized plantagram curves.

    Science.gov (United States)

    Hawes, M R; Heinemeyer, R; Sovak, D; Tory, B

    1994-07-01

    The averaging of outline shapes of the human foot for the purposes of determining information concerning foot shape and dimension within the context of comfort of fit of sport shoes is approached as a mathematical problem. An outline of the human footprint is obtained by standard procedures and the curvature is traced with a Hewlett Packard Digitizer. The paper describes the determination of an alignment axis, the identification of two ray centres and the division of the total curve into two overlapping arcs. Each arc is divided by equiangular rays which intersect chords between digitized points describing the arc. The radial distance of each ray is averaged within groups of foot lengths which vary by +/- 2.25 mm (approximately equal to 1/2 shoe size). The method has been used to determine average plantar curves in a study of 1197 North American males (Hawes and Sovak 1993).

  20. Books average previous decade of economic misery.

    Science.gov (United States)

    Bentley, R Alexander; Acerbi, Alberto; Ormerod, Paul; Lampos, Vasileios

    2014-01-01

    For the 20(th) century since the Depression, we find a strong correlation between a 'literary misery index' derived from English language books and a moving average of the previous decade of the annual U.S. economic misery index, which is the sum of inflation and unemployment rates. We find a peak in the goodness of fit at 11 years for the moving average. The fit between the two misery indices holds when using different techniques to measure the literary misery index, and this fit is significantly better than other possible correlations with different emotion indices. To check the robustness of the results, we also analysed books written in German language and obtained very similar correlations with the German economic misery index. The results suggest that millions of books published every year average the authors' shared economic experiences over the past decade.

  1. Books Average Previous Decade of Economic Misery

    Science.gov (United States)

    Bentley, R. Alexander; Acerbi, Alberto; Ormerod, Paul; Lampos, Vasileios

    2014-01-01

    For the 20th century since the Depression, we find a strong correlation between a ‘literary misery index’ derived from English language books and a moving average of the previous decade of the annual U.S. economic misery index, which is the sum of inflation and unemployment rates. We find a peak in the goodness of fit at 11 years for the moving average. The fit between the two misery indices holds when using different techniques to measure the literary misery index, and this fit is significantly better than other possible correlations with different emotion indices. To check the robustness of the results, we also analysed books written in German language and obtained very similar correlations with the German economic misery index. The results suggest that millions of books published every year average the authors' shared economic experiences over the past decade. PMID:24416159

  2. Exploiting scale dependence in cosmological averaging

    International Nuclear Information System (INIS)

    Mattsson, Teppo; Ronkainen, Maria

    2008-01-01

    We study the role of scale dependence in the Buchert averaging method, using the flat Lemaitre–Tolman–Bondi model as a testing ground. Within this model, a single averaging scale gives predictions that are too coarse, but by replacing it with the distance of the objects R(z) for each redshift z, we find an O(1%) precision at z<2 in the averaged luminosity and angular diameter distances compared to their exact expressions. At low redshifts, we show the improvement for generic inhomogeneity profiles, and our numerical computations further verify it up to redshifts z∼2. At higher redshifts, the method breaks down due to its inability to capture the time evolution of the inhomogeneities. We also demonstrate that the running smoothing scale R(z) can mimic acceleration, suggesting that it could be at least as important as the backreaction in explaining dark energy as an inhomogeneity induced illusion

  3. Stochastic Averaging and Stochastic Extremum Seeking

    CERN Document Server

    Liu, Shu-Jun

    2012-01-01

    Stochastic Averaging and Stochastic Extremum Seeking develops methods of mathematical analysis inspired by the interest in reverse engineering  and analysis of bacterial  convergence by chemotaxis and to apply similar stochastic optimization techniques in other environments. The first half of the text presents significant advances in stochastic averaging theory, necessitated by the fact that existing theorems are restricted to systems with linear growth, globally exponentially stable average models, vanishing stochastic perturbations, and prevent analysis over infinite time horizon. The second half of the text introduces stochastic extremum seeking algorithms for model-free optimization of systems in real time using stochastic perturbations for estimation of their gradients. Both gradient- and Newton-based algorithms are presented, offering the user the choice between the simplicity of implementation (gradient) and the ability to achieve a known, arbitrary convergence rate (Newton). The design of algorithms...

  4. Aperture averaging in strong oceanic turbulence

    Science.gov (United States)

    Gökçe, Muhsin Caner; Baykal, Yahya

    2018-04-01

    Receiver aperture averaging technique is employed in underwater wireless optical communication (UWOC) systems to mitigate the effects of oceanic turbulence, thus to improve the system performance. The irradiance flux variance is a measure of the intensity fluctuations on a lens of the receiver aperture. Using the modified Rytov theory which uses the small-scale and large-scale spatial filters, and our previously presented expression that shows the atmospheric structure constant in terms of oceanic turbulence parameters, we evaluate the irradiance flux variance and the aperture averaging factor of a spherical wave in strong oceanic turbulence. Irradiance flux variance variations are examined versus the oceanic turbulence parameters and the receiver aperture diameter are examined in strong oceanic turbulence. Also, the effect of the receiver aperture diameter on the aperture averaging factor is presented in strong oceanic turbulence.

  5. Regional averaging and scaling in relativistic cosmology

    International Nuclear Information System (INIS)

    Buchert, Thomas; Carfora, Mauro

    2002-01-01

    Averaged inhomogeneous cosmologies lie at the forefront of interest, since cosmological parameters such as the rate of expansion or the mass density are to be considered as volume-averaged quantities and only these can be compared with observations. For this reason the relevant parameters are intrinsically scale-dependent and one wishes to control this dependence without restricting the cosmological model by unphysical assumptions. In the latter respect we contrast our way to approach the averaging problem in relativistic cosmology with shortcomings of averaged Newtonian models. Explicitly, we investigate the scale-dependence of Eulerian volume averages of scalar functions on Riemannian three-manifolds. We propose a complementary view of a Lagrangian smoothing of (tensorial) variables as opposed to their Eulerian averaging on spatial domains. This programme is realized with the help of a global Ricci deformation flow for the metric. We explain rigorously the origin of the Ricci flow which, on heuristic grounds, has already been suggested as a possible candidate for smoothing the initial dataset for cosmological spacetimes. The smoothing of geometry implies a renormalization of averaged spatial variables. We discuss the results in terms of effective cosmological parameters that would be assigned to the smoothed cosmological spacetime. In particular, we find that on the smoothed spatial domain B-bar evaluated cosmological parameters obey Ω-bar B-bar m + Ω-bar B-bar R + Ω-bar B-bar A + Ω-bar B-bar Q 1, where Ω-bar B-bar m , Ω-bar B-bar R and Ω-bar B-bar A correspond to the standard Friedmannian parameters, while Ω-bar B-bar Q is a remnant of cosmic variance of expansion and shear fluctuations on the averaging domain. All these parameters are 'dressed' after smoothing out the geometrical fluctuations, and we give the relations of the 'dressed' to the 'bare' parameters. While the former provide the framework of interpreting observations with a 'Friedmannian bias

  6. Average: the juxtaposition of procedure and context

    Science.gov (United States)

    Watson, Jane; Chick, Helen; Callingham, Rosemary

    2014-09-01

    This paper presents recent data on the performance of 247 middle school students on questions concerning average in three contexts. Analysis includes considering levels of understanding linking definition and context, performance across contexts, the relative difficulty of tasks, and difference in performance for male and female students. The outcomes lead to a discussion of the expectations of the curriculum and its implementation, as well as assessment, in relation to students' skills in carrying out procedures and their understanding about the meaning of average in context.

  7. Average-case analysis of numerical problems

    CERN Document Server

    2000-01-01

    The average-case analysis of numerical problems is the counterpart of the more traditional worst-case approach. The analysis of average error and cost leads to new insight on numerical problems as well as to new algorithms. The book provides a survey of results that were mainly obtained during the last 10 years and also contains new results. The problems under consideration include approximation/optimal recovery and numerical integration of univariate and multivariate functions as well as zero-finding and global optimization. Background material, e.g. on reproducing kernel Hilbert spaces and random fields, is provided.

  8. Grassmann Averages for Scalable Robust PCA

    DEFF Research Database (Denmark)

    Hauberg, Søren; Feragen, Aasa; Black, Michael J.

    2014-01-01

    As the collection of large datasets becomes increasingly automated, the occurrence of outliers will increase—“big data” implies “big outliers”. While principal component analysis (PCA) is often used to reduce the size of data, and scalable solutions exist, it is well-known that outliers can...... to vectors (subspaces) or elements of vectors; we focus on the latter and use a trimmed average. The resulting Trimmed Grassmann Average (TGA) is particularly appropriate for computer vision because it is robust to pixel outliers. The algorithm has low computational complexity and minimal memory requirements...

  9. EVIDENCE FOR ULTRA-FAST OUTFLOWS IN RADIO-QUIET ACTIVE GALACTIC NUCLEI. II. DETAILED PHOTOIONIZATION MODELING OF Fe K-SHELL ABSORPTION LINES

    International Nuclear Information System (INIS)

    Tombesi, F.; Cappi, M.; Dadina, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s –1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ∼10,000 km s –1 (∼0.03c) up to ∼100,000 km s –1 (∼0.3c), with a peak and mean value of ∼42,000 km s –1 (∼0.14c). The ionization parameter is very high and in the range log ξ ∼ 3-6 erg s –1 cm, with a mean value of log ξ ∼ 4.2 erg s –1 cm. The associated column densities are also large, in the range N H ∼ 10 22 -10 24 cm –2 , with a mean value of N H ∼ 10 23 cm –2 . We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected

  10. THE SPITZER c2d SURVEY OF NEARBY DENSE CORES: JET AND MOLECULAR OUTFLOW ASSOCIATED WITH A YOUNG STELLAR OBJECT IN CORE A OF L1251

    International Nuclear Information System (INIS)

    Lee, Jeong-Eun; Kim, Il-Suk; Choi, Yunhee; Lee, Ho-Gyu; Shinn, Jong-Ho; Dunham, Michael M.; Evans, Neal J.; Kim, Chang Hee; Bourke, Tyler L.

    2010-01-01

    A long infrared jet has been discovered by the Spitzer c2d Legacy Program in core A of L1251. It is associated with a very embedded Class 0 object with an accretion luminosity of about 0.9 L sun derived by radiative transfer model fitting to the observed spectral energy distribution. Comparing the observed Infrared Array Camera colors along the infrared jet with those calculated from a model of an admixture of gas with a power-law temperature distribution indicates that the jet is possibly created by a paraboloidal bow shock propagating into the ambient medium of n(H 2 ) = 10 5 cm -3 . In addition, the variation of the power-law index along the jet suggests that the portion of hot gas decreases with distance from the jet engine. The molecular outflow in this region has been mapped for the first time using CO data. From the calculated outflow momentum flux, a very strong lower limit to the average accretion luminosity is 3.6 sin i/cos 3 i L sun , indicative of a decrease in the accretion rate with time.

  11. Simulation of water movement and isoproturon behaviour in a heavy clay soil using the MACRO model

    Directory of Open Access Journals (Sweden)

    T. J. Besien

    1997-01-01

    Full Text Available In this paper, the dual-porosity MACRO model has been used to investigate methods of reducing leaching of isoproturon from a structured heavy clay soil. The MACRO model was applied to a pesticide leaching data-set generated from a plot scale experiment on a heavy clay soil at the Oxford University Farm, Wytham, England. The field drain was found to be the most important outflow from the plot in terms of pesticide removal. Therefore, this modelling exercise concentrated on simulating field drain flow. With calibration of field-saturated and micropore saturated hydraulic conductivity, the drain flow hydrographs were simulated during extended periods of above average rainfall, with both the hydrograph shape and peak flows agreeing well. Over the whole field season, the observed drain flow water budget was well simulated. However, the first and second drain flow events after pesticide application were not simulated satisfactorily. This is believed to be due to a poor simulation of evapotranspiration during a period of low rainfall around the pesticide application day. Apart from an initial rapid drop in the observed isoproturon soil residue, the model simulated isoproturon residues during the 100 days after pesticide application reasonably well. Finally, the calibrated model was used to show that changes in agricultural practice (deep ploughing, creating fine consolidated seed beds and organic matter applications could potentially reduce pesticide leaching to surface waters by up to 60%.

  12. Model averaging, optimal inference and habit formation

    Directory of Open Access Journals (Sweden)

    Thomas H B FitzGerald

    2014-06-01

    Full Text Available Postulating that the brain performs approximate Bayesian inference generates principled and empirically testable models of neuronal function – the subject of much current interest in neuroscience and related disciplines. Current formulations address inference and learning under some assumed and particular model. In reality, organisms are often faced with an additional challenge – that of determining which model or models of their environment are the best for guiding behaviour. Bayesian model averaging – which says that an agent should weight the predictions of different models according to their evidence – provides a principled way to solve this problem. Importantly, because model evidence is determined by both the accuracy and complexity of the model, optimal inference requires that these be traded off against one another. This means an agent’s behaviour should show an equivalent balance. We hypothesise that Bayesian model averaging plays an important role in cognition, given that it is both optimal and realisable within a plausible neuronal architecture. We outline model averaging and how it might be implemented, and then explore a number of implications for brain and behaviour. In particular, we propose that model averaging can explain a number of apparently suboptimal phenomena within the framework of approximate (bounded Bayesian inference, focussing particularly upon the relationship between goal-directed and habitual behaviour.

  13. Generalized Jackknife Estimators of Weighted Average Derivatives

    DEFF Research Database (Denmark)

    Cattaneo, Matias D.; Crump, Richard K.; Jansson, Michael

    With the aim of improving the quality of asymptotic distributional approximations for nonlinear functionals of nonparametric estimators, this paper revisits the large-sample properties of an important member of that class, namely a kernel-based weighted average derivative estimator. Asymptotic...

  14. Average beta measurement in EXTRAP T1

    International Nuclear Information System (INIS)

    Hedin, E.R.

    1988-12-01

    Beginning with the ideal MHD pressure balance equation, an expression for the average poloidal beta, Β Θ , is derived. A method for unobtrusively measuring the quantities used to evaluate Β Θ in Extrap T1 is described. The results if a series of measurements yielding Β Θ as a function of externally applied toroidal field are presented. (author)

  15. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS

    International Nuclear Information System (INIS)

    2005-01-01

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department

  16. Bayesian Averaging is Well-Temperated

    DEFF Research Database (Denmark)

    Hansen, Lars Kai

    2000-01-01

    Bayesian predictions are stochastic just like predictions of any other inference scheme that generalize from a finite sample. While a simple variational argument shows that Bayes averaging is generalization optimal given that the prior matches the teacher parameter distribution the situation is l...

  17. Gibbs equilibrium averages and Bogolyubov measure

    International Nuclear Information System (INIS)

    Sankovich, D.P.

    2011-01-01

    Application of the functional integration methods in equilibrium statistical mechanics of quantum Bose-systems is considered. We show that Gibbs equilibrium averages of Bose-operators can be represented as path integrals over a special Gauss measure defined in the corresponding space of continuous functions. We consider some problems related to integration with respect to this measure

  18. High average-power induction linacs

    International Nuclear Information System (INIS)

    Prono, D.S.; Barrett, D.; Bowles, E.; Caporaso, G.J.; Chen, Yu-Jiuan; Clark, J.C.; Coffield, F.; Newton, M.A.; Nexsen, W.; Ravenscroft, D.; Turner, W.C.; Watson, J.A.

    1989-01-01

    Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of ∼ 50-ns duration pulses to > 100 MeV. In this paper the authors report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs

  19. Function reconstruction from noisy local averages

    International Nuclear Information System (INIS)

    Chen Yu; Huang Jianguo; Han Weimin

    2008-01-01

    A regularization method is proposed for the function reconstruction from noisy local averages in any dimension. Error bounds for the approximate solution in L 2 -norm are derived. A number of numerical examples are provided to show computational performance of the method, with the regularization parameters selected by different strategies

  20. A singularity theorem based on spatial averages

    Indian Academy of Sciences (India)

    journal of. July 2007 physics pp. 31–47. A singularity theorem based on spatial ... In this paper I would like to present a result which confirms – at least partially – ... A detailed analysis of how the model fits in with the .... Further, the statement that the spatial average ...... Financial support under grants FIS2004-01626 and no.

  1. Multiphase averaging of periodic soliton equations

    International Nuclear Information System (INIS)

    Forest, M.G.

    1979-01-01

    The multiphase averaging of periodic soliton equations is considered. Particular attention is given to the periodic sine-Gordon and Korteweg-deVries (KdV) equations. The periodic sine-Gordon equation and its associated inverse spectral theory are analyzed, including a discussion of the spectral representations of exact, N-phase sine-Gordon solutions. The emphasis is on physical characteristics of the periodic waves, with a motivation from the well-known whole-line solitons. A canonical Hamiltonian approach for the modulational theory of N-phase waves is prescribed. A concrete illustration of this averaging method is provided with the periodic sine-Gordon equation; explicit averaging results are given only for the N = 1 case, laying a foundation for a more thorough treatment of the general N-phase problem. For the KdV equation, very general results are given for multiphase averaging of the N-phase waves. The single-phase results of Whitham are extended to general N phases, and more importantly, an invariant representation in terms of Abelian differentials on a Riemann surface is provided. Several consequences of this invariant representation are deduced, including strong evidence for the Hamiltonian structure of N-phase modulational equations

  2. A dynamic analysis of moving average rules

    NARCIS (Netherlands)

    Chiarella, C.; He, X.Z.; Hommes, C.H.

    2006-01-01

    The use of various moving average (MA) rules remains popular with financial market practitioners. These rules have recently become the focus of a number empirical studies, but there have been very few studies of financial market models where some agents employ technical trading rules of the type

  3. Essays on model averaging and political economics

    NARCIS (Netherlands)

    Wang, W.

    2013-01-01

    This thesis first investigates various issues related with model averaging, and then evaluates two policies, i.e. West Development Drive in China and fiscal decentralization in U.S, using econometric tools. Chapter 2 proposes a hierarchical weighted least squares (HWALS) method to address multiple

  4. 7 CFR 1209.12 - On average.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false On average. 1209.12 Section 1209.12 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... CONSUMER INFORMATION ORDER Mushroom Promotion, Research, and Consumer Information Order Definitions § 1209...

  5. High average-power induction linacs

    International Nuclear Information System (INIS)

    Prono, D.S.; Barrett, D.; Bowles, E.

    1989-01-01

    Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of /approximately/ 50-ns duration pulses to > 100 MeV. In this paper we report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs

  6. Average Costs versus Net Present Value

    NARCIS (Netherlands)

    E.A. van der Laan (Erwin); R.H. Teunter (Ruud)

    2000-01-01

    textabstractWhile the net present value (NPV) approach is widely accepted as the right framework for studying production and inventory control systems, average cost (AC) models are more widely used. For the well known EOQ model it can be verified that (under certain conditions) the AC approach gives

  7. Reliability Estimates for Undergraduate Grade Point Average

    Science.gov (United States)

    Westrick, Paul A.

    2017-01-01

    Undergraduate grade point average (GPA) is a commonly employed measure in educational research, serving as a criterion or as a predictor depending on the research question. Over the decades, researchers have used a variety of reliability coefficients to estimate the reliability of undergraduate GPA, which suggests that there has been no consensus…

  8. Configuring calendar variation based on time series regression method for forecasting of monthly currency inflow and outflow in Central Java

    Science.gov (United States)

    Setiawan, Suhartono, Ahmad, Imam Safawi; Rahmawati, Noorgam Ika

    2015-12-01

    Bank Indonesia (BI) as the central bank of Republic Indonesiahas a single overarching objective to establish and maintain rupiah stability. This objective could be achieved by monitoring traffic of inflow and outflow money currency. Inflow and outflow are related to stock and distribution of money currency around Indonesia territory. It will effect of economic activities. Economic activities of Indonesia,as one of Moslem country, absolutely related to Islamic Calendar (lunar calendar), that different with Gregorian calendar. This research aims to forecast the inflow and outflow money currency of Representative Office (RO) of BI Semarang Central Java region. The results of the analysis shows that the characteristics of inflow and outflow money currency influenced by the effects of the calendar variations, that is the day of Eid al-Fitr (moslem holyday) as well as seasonal patterns. In addition, the period of a certain week during Eid al-Fitr also affect the increase of inflow and outflow money currency. The best model based on the value of the smallestRoot Mean Square Error (RMSE) for inflow data is ARIMA model. While the best model for predicting the outflow data in RO of BI Semarang is ARIMAX model or Time Series Regression, because both of them have the same model. The results forecast in a period of 2015 shows an increase of inflow money currency happened in August, while the increase in outflow money currency happened in July.

  9. Tendon surveillance requirements - average tendon force

    International Nuclear Information System (INIS)

    Fulton, J.F.

    1982-01-01

    Proposed Rev. 3 to USNRC Reg. Guide 1.35 discusses the need for comparing, for individual tendons, the measured and predicted lift-off forces. Such a comparison is intended to detect any abnormal tendon force loss which might occur. Recognizing that there are uncertainties in the prediction of tendon losses, proposed Guide 1.35.1 has allowed specific tolerances on the fundamental losses. Thus, the lift-off force acceptance criteria for individual tendons appearing in Reg. Guide 1.35, Proposed Rev. 3, is stated relative to a lower bound predicted tendon force, which is obtained using the 'plus' tolerances on the fundamental losses. There is an additional acceptance criterion for the lift-off forces which is not specifically addressed in these two Reg. Guides; however, it is included in a proposed Subsection IWX to ASME Code Section XI. This criterion is based on the overriding requirement that the magnitude of prestress in the containment structure be sufficeint to meet the minimum prestress design requirements. This design requirement can be expressed as an average tendon force for each group of vertical hoop, or dome tendons. For the purpose of comparing the actual tendon forces with the required average tendon force, the lift-off forces measured for a sample of tendons within each group can be averaged to construct the average force for the entire group. However, the individual lift-off forces must be 'corrected' (normalized) prior to obtaining the sample average. This paper derives the correction factor to be used for this purpose. (orig./RW)

  10. Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart

    Directory of Open Access Journals (Sweden)

    Robert E. Poelmann

    2017-05-01

    Full Text Available Abstract Background Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. Results We studied embryonic stages of reptile hearts (lizard, turtle and crocodile and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard or it is vestigial (turtle. Crocodiles

  11. Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart.

    Science.gov (United States)

    Poelmann, Robert E; Gittenberger-de Groot, Adriana C; Biermans, Marcel W M; Dolfing, Anne I; Jagessar, Armand; van Hattum, Sam; Hoogenboom, Amanda; Wisse, Lambertus J; Vicente-Steijn, Rebecca; de Bakker, Merijn A G; Vonk, Freek J; Hirasawa, Tatsuya; Kuratani, Shigeru; Richardson, Michael K

    2017-01-01

    Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. We studied embryonic stages of reptile hearts (lizard, turtle and crocodile) and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population) forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard) or it is vestigial (turtle). Crocodiles are unique in bearing a central shunt, the

  12. Cloud Spirals and Outflow in Tropical Storm Katrina

    Science.gov (United States)

    2005-01-01

    On Tuesday, August 30, 2005, NASA's Multi-angle Imaging SpectroRadiometer retrieved cloud-top heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee valley. At this time Katrina was weakening and no longer classified as a hurricane, and would soon become an extratropical depression. Measurements such as these can help atmospheric scientists compare results of computer-generated hurricane simulations with observed conditions, ultimately allowing them to better represent and understand physical processes occurring in hurricanes. Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are characterized by an inward counterclockwise (cyclonic) rotation towards the center. It is less widely known that, at high altitudes, outward-spreading bands of cloud rotate in a clockwise (anticyclonic) direction. The image on the left shows the retrieved cloud-tracked winds as red arrows superimposed across the natural color view from MISR's nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper clouds are apparent in these images. The speeds for the clockwise upper level winds have typical values between 40 and 45 m/s (144-162 km/hr). The low level counterclockwise winds have typical values between 7 and 24 m/s (25-86 km/hr), weakening with distance from the storm center. The image on the right displays the cloud-top height retrievals. Areas where cloud heights could not be retrieved are shown in dark gray. Both the wind velocity vectors and the cloud-top height field were produced by automated computer recognition of displacements in spatial features within successive MISR images acquired at different view angles and at slightly different times. The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe

  13. Post-model selection inference and model averaging

    Directory of Open Access Journals (Sweden)

    Georges Nguefack-Tsague

    2011-07-01

    Full Text Available Although model selection is routinely used in practice nowadays, little is known about its precise effects on any subsequent inference that is carried out. The same goes for the effects induced by the closely related technique of model averaging. This paper is concerned with the use of the same data first to select a model and then to carry out inference, in particular point estimation and point prediction. The properties of the resulting estimator, called a post-model-selection estimator (PMSE, are hard to derive. Using selection criteria such as hypothesis testing, AIC, BIC, HQ and Cp, we illustrate that, in terms of risk function, no single PMSE dominates the others. The same conclusion holds more generally for any penalised likelihood information criterion. We also compare various model averaging schemes and show that no single one dominates the others in terms of risk function. Since PMSEs can be regarded as a special case of model averaging, with 0-1 random-weights, we propose a connection between the two theories, in the frequentist approach, by taking account of the selection procedure when performing model averaging. We illustrate the point by simulating a simple linear regression model.

  14. Fluid mechanical consequences of pendular activity, segmentation and pyloric outflow in the proximal duodenum of the rat and the guinea pig.

    Science.gov (United States)

    de Loubens, Clément; Lentle, Roger G; Love, Richard J; Hulls, Corrin; Janssen, Patrick W M

    2013-06-06

    We conducted numerical experiments to study the influence of non-propagating longitudinal and circular contractions, i.e. pendular activity and segmentation, respectively, on flow and mixing in the proximal duodenum. A lattice-Boltzmann numerical method was developed to simulate the fluid mechanical consequences for each of 22 randomly selected sequences of high-definition video of real longitudinal and radial contractile activity in the isolated proximal duodenum of the rat and guinea pig. During pendular activity in the rat duodenum, the flow was characterized by regions of high shear rate. Mixing was so governed by shearing deformation of the fluid that increased the interface between adjacent domains and accelerated their inter-diffusion (for diffusion coefficients approx. less than 10(-8) m² s(-1)). When pendular activity was associated with a slow gastric outflow characteristic of post-prandial period, the dispersion was also improved, especially near the walls. Mixing was not promoted by isolated segmentative contractions in the guinea pig duodenum and not notably influenced by pylorus outflow. We concluded that pendular activity generates mixing of viscous fluids 'in situ' and accelerates the diffusive mass transfer, whereas segmentation may be more important in mixing particulate suspensions with high solid volume ratios.

  15. Fluid mechanical consequences of pendular activity, segmentation and pyloric outflow in the proximal duodenum of the rat and the guinea pig

    Science.gov (United States)

    de Loubens, Clément; Lentle, Roger G.; Love, Richard J.; Hulls, Corrin; Janssen, Patrick W. M.

    2013-01-01

    We conducted numerical experiments to study the influence of non-propagating longitudinal and circular contractions, i.e. pendular activity and segmentation, respectively, on flow and mixing in the proximal duodenum. A lattice-Boltzmann numerical method was developed to simulate the fluid mechanical consequences for each of 22 randomly selected sequences of high-definition video of real longitudinal and radial contractile activity in the isolated proximal duodenum of the rat and guinea pig. During pendular activity in the rat duodenum, the flow was characterized by regions of high shear rate. Mixing was so governed by shearing deformation of the fluid that increased the interface between adjacent domains and accelerated their inter-diffusion (for diffusion coefficients approx. less than 10−8 m² s−1). When pendular activity was associated with a slow gastric outflow characteristic of post-prandial period, the dispersion was also improved, especially near the walls. Mixing was not promoted by isolated segmentative contractions in the guinea pig duodenum and not notably influenced by pylorus outflow. We concluded that pendular activity generates mixing of viscous fluids ‘in situ’ and accelerates the diffusive mass transfer, whereas segmentation may be more important in mixing particulate suspensions with high solid volume ratios. PMID:23536539

  16. ANALYSIS OF THE FACTORS AFFECTING THE AVERAGE

    Directory of Open Access Journals (Sweden)

    Carmen BOGHEAN

    2013-12-01

    Full Text Available Productivity in agriculture most relevantly and concisely expresses the economic efficiency of using the factors of production. Labour productivity is affected by a considerable number of variables (including the relationship system and interdependence between factors, which differ in each economic sector and influence it, giving rise to a series of technical, economic and organizational idiosyncrasies. The purpose of this paper is to analyse the underlying factors of the average work productivity in agriculture, forestry and fishing. The analysis will take into account the data concerning the economically active population and the gross added value in agriculture, forestry and fishing in Romania during 2008-2011. The distribution of the average work productivity per factors affecting it is conducted by means of the u-substitution method.

  17. Weighted estimates for the averaging integral operator

    Czech Academy of Sciences Publication Activity Database

    Opic, Bohumír; Rákosník, Jiří

    2010-01-01

    Roč. 61, č. 3 (2010), s. 253-262 ISSN 0010-0757 R&D Projects: GA ČR GA201/05/2033; GA ČR GA201/08/0383 Institutional research plan: CEZ:AV0Z10190503 Keywords : averaging integral operator * weighted Lebesgue spaces * weights Subject RIV: BA - General Mathematics Impact factor: 0.474, year: 2010 http://link.springer.com/article/10.1007%2FBF03191231

  18. Average Transverse Momentum Quantities Approaching the Lightfront

    OpenAIRE

    Boer, Daniel

    2015-01-01

    In this contribution to Light Cone 2014, three average transverse momentum quantities are discussed: the Sivers shift, the dijet imbalance, and the $p_T$ broadening. The definitions of these quantities involve integrals over all transverse momenta that are overly sensitive to the region of large transverse momenta, which conveys little information about the transverse momentum distributions of quarks and gluons inside hadrons. TMD factorization naturally suggests alternative definitions of su...

  19. Time-averaged MSD of Brownian motion

    OpenAIRE

    Andreanov, Alexei; Grebenkov, Denis

    2012-01-01

    We study the statistical properties of the time-averaged mean-square displacements (TAMSD). This is a standard non-local quadratic functional for inferring the diffusion coefficient from an individual random trajectory of a diffusing tracer in single-particle tracking experiments. For Brownian motion, we derive an exact formula for the Laplace transform of the probability density of the TAMSD by mapping the original problem onto chains of coupled harmonic oscillators. From this formula, we de...

  20. FROM THE CONVERGENCE OF FILAMENTS TO DISK-OUTFLOW ACCRETION: MASSIVE STAR FORMATION IN W33A

    International Nuclear Information System (INIS)

    Galvan-Madrid, Roberto; Zhang Qizhou; Keto, Eric; Ho, Paul T. P.; Pineda, Jaime E.; Zapata, Luis A.; RodrIguez, Luis F.; Vazquez-Semadeni, Enrique

    2010-01-01

    Interferometric observations of the W33A massive star formation region, performed with the Submillimeter Array and the Very Large Array at resolutions from 5'' (0.1 pc) to 0.''5 (0.01 pc), are presented. Our three main findings are: (1) parsec-scale, filamentary structures of cold molecular gas are detected. Two filaments at different velocities intersect in the zone where the star formation is occurring. This is consistent with triggering of the star formation activity by the convergence of such filaments, as predicted by numerical simulations of star formation initiated by converging flows. (2) The two dusty cores (MM1 and MM2) at the intersection of the filaments are found to be at different evolutionary stages, and each of them is resolved into multiple condensations. MM1 and MM2 have markedly different temperatures, continuum spectral indices, molecular-line spectra, and masses of both stars and gas. (3) The dynamics of the 'hot-core' MM1 indicates the presence of a rotating disk in its center (MM1-Main) around a faint free-free source. The stellar mass is estimated to be ∼10 M sun . A massive molecular outflow is observed along the rotation axis of the disk.

  1. Mathematical and physical model of gravity-fed infusion outflow: application to soft-bag-packed solutions.

    Science.gov (United States)

    Simon, N; Décaudin, B; Lannoy, D; Barthélémy, C; Lemdani, M; Odou, P

    2011-12-01

    Gravity-fed infusion (GFI) systems are acknowledged as being unable to keep their flow-rate constant. This may affect drug plasma levels such as aminoglycosides. Numerous factors have previously been cited, but their relative importance has never been quantified so far. The objective of this work is to identify the main factors that influence GFI in vitro outflow and to propose a mathematical model of flow-rate evolution as a function of time. In this model, pressure loss and infusion device creep have been considered as the main variation factors. Concomitantly, two experiments were undertaken. Firstly, the flow-rate evolution of an in vitro infusion of 250 mL of dextrose 5% was assessed. Secondly, the creep occurring on an infusion device was measured through a stress relaxation experiment. The experimental infusion flow-rate decreased by as much as 28.5% over 1 h. Simulated and experimental data are well correlated (r = 0.987; P model should help to explain the differences observed in drug plasma levels with gravity-fed devices.

  2. Prediction of rumen microbial outflow based on urinary excretion of purine derivatives

    International Nuclear Information System (INIS)

    Nolan, J.V.

    1999-01-01

    The method for predicting microbial protein outflow from the rumen based on the excretion of purine derivatives (PD) in the urine is being increasingly used by nutritionists. In contrast to methods that depend on estimates of digesta flow, the PD method does not require animals to be fitted surgically with cannulae into the gut, and studies can be performed with minimal disturbance to the experimental animals. Methods of analysis of PD have been improved and standardized. Certain assumptions, however, are required that could lead to errors when this method is used to predict microbial protein outflow from the rumen. The need for further investigation of these assumptions by means of isotopic tracers and other techniques is examined. (author)

  3. Acromegaly-induced cardiomyopathy with dobutamine-induced outflow tract obstruction.

    Science.gov (United States)

    Abdelsalam, Mahmoud A; Nippoldt, Todd B; Geske, Jeffrey B

    2016-03-09

    A 50-year-old man with a history of acromegaly was referred for preoperative cardiac evaluation preceding trans-sphenoidal resection of a pituitary macroadenoma. Dobutamine stress echocardiography was negative for myocardial ischaemia. Resting left ventricular (LV) LV ejection fraction (LVEF) was 64% and there was hypertrophy of ventricular septum (18 mm) without resting LV outflow tract obstruction. With 40 µg/kg/min of dobutamine, the LVEF became hyperdynamic at 80%, and there was a maximal instantaneous LV outflow tract gradient of 77 mm Hg. There was no delayed myocardial enhancement on cardiac MRI and the pattern of hypertrophy was concentric. Acromegaly-induced cardiomyopathy can mimic hypertrophic cardiomyopathy in the setting of dobutamine provocation. Because cardiomyopathy is an important cause of mortality in acromegaly, diagnosis and appropriate management are critical to improve survival. 2016 BMJ Publishing Group Ltd.

  4. A Model of Silicate Grain Nucleation and Growth in Circumstellar Outflows

    Science.gov (United States)

    Paquette, John A.; Ferguson, Frank T.; Nuth, Joseph A., III

    2011-01-01

    Based on its abundance, high bond energy, and recent measurements of its vapor pressure SiO is a natural candidate for dust nucleation in circumstellar outflows around asymptotic giant branch stars. In this paper, we describe a model of the nucleation and growth of silicate dust in such outflows. The sensitivity of the model to varying choices of poorly constrained chemical parameters is explored, and the merits of using scaled rather than classical nucleation theory are briefly considered, An elaboration of the model that includes magnesium and iron as growth species is then presented and discussed. The composition of the bulk of the grains derived from the model is consistent with olivines and pyroxenes, but somewhat metal-rich grains and very small, nearly pure SiO grains are also produced,

  5. Model for collimated outflows in molecular clouds and the case of HH 7-11

    Energy Technology Data Exchange (ETDEWEB)

    Silvestro, G; Ferrari, A; Rosner, R; Trussoni, E; Tsinganos, K

    1987-01-15

    Modelling is carried out for collimated outflows of high-velocity gas in molecular clouds, which is often observed to be associated with linear chains of optical emission knots. A wind-flow model is proposed to account for the phenomenon, based on the structural similarities between the outflows and jets from active galactic nuclei and quasars. The chain of Herbig-Haro objects HH7-11 is used to illustrate the proposal. The model is based on flows in a channel of variable cross-sectional area due to Kelvin-Helmholtz instabilities between the flow and the ambient medium. Solutions of the Mach number equation for such a channel are presented, which possess multiple critical points and shocks identified with observed optical knots. (U.K.).

  6. Transcatheter Pulmonary Valve Replacement for Right Ventricular Outflow Tract Conduit Dysfunction After the Ross Procedure

    DEFF Research Database (Denmark)

    Gillespie, Matthew J; McElhinney, Doff B; Kreutzer, Jacqueline

    2015-01-01

    BACKGROUND: Right ventricular outflow tract (RVOT) conduit dysfunction is a limitation of the Ross procedure. Transcatheter pulmonary valve replacement (TPVR) could alter the impact of conduit dysfunction and the risk-benefit balance for the Ross procedure. METHODS: Retrospective review of databa......BACKGROUND: Right ventricular outflow tract (RVOT) conduit dysfunction is a limitation of the Ross procedure. Transcatheter pulmonary valve replacement (TPVR) could alter the impact of conduit dysfunction and the risk-benefit balance for the Ross procedure. METHODS: Retrospective review....... Of these, 56 (84%) received a Melody valve; in 5 of the 11 patients who did not, the implant was aborted due to concern for coronary artery compression, and 1 implanted patient required emergent surgery for left coronary compression. The RVOT gradient decreased from a median 38 mm Hg to 13.5 mm Hg (p

  7. Probing the connection between the accretion disk, outflows and the jet in 3C111

    Science.gov (United States)

    Tombesi, Francesco

    2011-10-01

    Recent XMM-Newton and Suzaku observations of 3C111 demonstrated the presence of ultra-fast outflows (UFOs) with v~0.1c and their relation with the accretion disk. Independent studies found that X-ray dips are followed by ejection of superluminal radio knots, therefore providing a proof of the disk-jet connection. We acquired evidence that UFOs are preferentially present between X-ray dips and new knots, possibly indicating also a link between disk outflows and the jet. The goal of this XMM-Newton proposal is to confirm this evidence. Given the strong correlation with X-rays, we will use an ongoing optical monitoring campaign to trigger a 90ks observation within two days of a dip to detect a UFO and we request a possible additional 60ks >15 days after to compare with the non-dipped state.

  8. [The reasonable use of right ventricular protection strategy in right ventricular outflow tract reconstruction].

    Science.gov (United States)

    Zhang, Y; Yuan, H Y; Liu, X B; Wen, S S; Xu, G; Cui, H J; Zhuang, J; Chen, J M

    2018-06-01

    As a result of right ventricular outflow tract reconstruction, which is the important and basic step of complex cardiac surgery, the blood flow of right ventricular outflow tract is unobstructed, while pulmonary valve regurgitation and right heart dysfunction could be happened. These problems are often ignored in early days, more and more cases of right heart dysfunction need clinical intervention, which is quite difficult and less effective. How to protect effectively the right ventricular function is the focus. At present main methods to protect the right ventricular function include trying to avoid or reduce length of right ventricular incision, reserving or rebuilding the function of the pulmonary valve, using growth potential material for surgery. The protection of the right ventricular function is a systemic project, it involves many aspects, single measures is difficult to provide complete protection, only the comprehensive use of various protection strategy, can help to improve the long-term prognosis.

  9. Particulate waste outflow from fish-farming cages. How much is uneaten feed?

    Science.gov (United States)

    Ballester-Moltó, M; Sanchez-Jerez, P; Cerezo-Valverde, J; Aguado-Giménez, F

    2017-06-15

    Particulate wastes drive benthic organic enrichment from cage fish farming. Differentiation between faeces and uneaten feed estimates at cage level are of great value to both economize the feeding process and reduce waste. This study estimates the particulate waste outflowing cages at different depths and orientations, and the wasted feed component by combining in situ measurements and modelling. Particulate matter flux (PMF) was greater vertically through the cage bottoms (60.89%), but lateral outflow was also substantial (39.11%). PMF occurs all around the cages, and the influence of the mainstream current was low. Wasted feed was greatly variable, reaching high values (about 50% of supplied feed. The self-application of feed wastage monitoring and estimates by fish farmers is recommended to improve sustainability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Compact radio and infrared sources near the centre of the bipolar outflow NGC 2264D

    International Nuclear Information System (INIS)

    Mendoza, E.E.; Rodriguez, L.F.; Chavarria-K, C.; Neri, L.

    1990-01-01

    A multi-frequency study of the central region of the bipolar outflow NGC 2264D in the Monoceros OB1 molecular cloud has been made in an attempt to localize and understand its driving source. We have detected a weak (≅ 0.6 mJy) radio continuum source at 6 cm, using the VLA; a bright (≅ 270 Jy) H 2 O maser, using the Haystack Observatory telescope; and near-infrared counterparts to these sources at San Pedro Martir Observatory. Stromgren and JHKL'M photometry of stellar objects in the region was also carried out at this observatory. The star-like object W166, a probable Herbig Be/Ae star, which has strong Hα emission and a near-infrared excess, is located closest to the centroid of the bipolar outflow and is probably its driving source. (author)

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