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Sample records for large scale plasma

  1. Large-scale quantization from local correlations in space plasmas

    NASA Astrophysics Data System (ADS)

    Livadiotis, George; McComas, David J.

    2014-05-01

    This study examines the large-scale quantization that can characterize the phase space of certain physical systems. Plasmas are such systems where large-scale quantization, ħ*, is caused by Debye shielding that structures correlations between particles. The value of ħ* is constant—some 12 orders of magnitude larger than the Planck constant—across a wide range of space plasmas, from the solar wind in the inner heliosphere to the distant plasma in the inner heliosheath and the local interstellar medium. This paper develops the foundation and advances the understanding of the concept of plasma quantization; in particular, we (i) show the analogy of plasma to Planck quantization, (ii) show the key points of plasma quantization, (iii) construct some basic quantum mechanical concepts for the large-scale plasma quantization, (iv) investigate the correlation between plasma parameters that implies plasma quantization, when it is approximated by a relation between the magnetosonic energy and the plasma frequency, (v) analyze typical space plasmas throughout the heliosphere and show the constancy of plasma quantization over many orders of magnitude in plasma parameters, (vi) analyze Advanced Composition Explorer (ACE) solar wind measurements to develop another measurement of the value of ħ*, and (vii) apply plasma quantization to derive unknown plasma parameters when some key observable is missing.

  2. Large-Scale Structure of Magnetospheric Plasma

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Delcourt, D. C.

    1995-01-01

    Recent investigations of magnetospheric plasma structure are summarized under the broad categories of empirical models, transport across boundaries, formation, and dynamics of the plasma sheet. This report reviews work in these areas during the period 1991 to 1993. Fully three-dimensional empirical models and simulations have become important contributors to our understanding of the magnetospheric system. Some new structural concepts have appeared in the literature: the 'entry boundary' and 'geo-pause', the plasma sheet 'region 1 vortices', the 'low-energy layer', the 'adia-baticity boundary' or 'wall region', and a region in the tail to which we refer as the 'injection port'. Traditional structural concepts have also been the subject of recent study, notably the plasmapause, the magnetopause, and the plasma sheet. Significant progress has been made in understanding the nature of plasma sheet formation and dynamics, but the acceleration of electrons to high energy remains somewhat mysterious.

  3. Scaled Laboratory Collisionless Shock Experiments in the Large Plasma Device

    NASA Astrophysics Data System (ADS)

    Clark, S. E.; Schaeffer, D.; Everson, E.; Bondarenko, A.; Winske, D.; Constantin, C.; Niemann, C.

    2013-12-01

    Collisionless shocks in space plasmas have been investigated since the fifties and are typically studied via in-situ satellite observations, which are limited due to the large structure of collisionless shocks in space environments relative to the satellite observation platform. Scaled, repeatable experiments in the Large Plasma Device (LAPD) at UCLA provide a test bed for studying collisionless shocks in the laboratory, where questions of ion and electron heating and acceleration can be addressed and examined in detail. The experiments are performed by ablating a graphite or plastic target using the Raptor kilojoule-class laser facility at UCLA. The laser provides an on-target energy in the range of 100-500 J that drives a super-Alfvénic (MA > 1) debris plasma across a background magnetic field (200-800 G) into the ambient, magnetized LAPD plasma. Typical plasma parameters in the LAPD consist of a H+ or He+ ambient plasma with a core column (diameter > 20 cm ) density ni ~ 1013 cm-3 and electron temperature Te ~ 10 eV embedded in a larger plasma discharge (diameter ~ 80 cm) of density ni ~ 1012 cm-3 and Te ~ 5 eV. The ambient ion temperature is Ti ~ 1 eV. Experimental results from the latest collisionless shock campaign will be presented and compared with two dimensional hybrid simulations of the experiment. Fielded diagnostics include Thomson scattering, ion spectroscopy, magnetic flux probes, Langmuir probes, and microwave reflectometry.

  4. A model of plasma heating by large-scale flow

    NASA Astrophysics Data System (ADS)

    Pongkitiwanichakul, P.; Cattaneo, F.; Boldyrev, S.; Mason, J.; Perez, J. C.

    2015-12-01

    In this work, we study the process of energy dissipation triggered by a slow large-scale motion of a magnetized conducting fluid. Our consideration is motivated by the problem of heating the solar corona, which is believed to be governed by fast reconnection events set off by the slow motion of magnetic field lines anchored in the photospheric plasma. To elucidate the physics governing the disruption of the imposed laminar motion and the energy transfer to small scales, we propose a simplified model where the large-scale motion of magnetic field lines is prescribed not at the footpoints but rather imposed volumetrically. As a result, the problem can be treated numerically with an efficient, highly accurate spectral method, allowing us to use a resolution and statistical ensemble exceeding those of the previous work. We find that, even though the large-scale deformations are slow, they eventually lead to reconnection events that drive a turbulent state at smaller scales. The small-scale turbulence displays many of the universal features of field-guided magnetohydrodynamic turbulence like a well-developed inertial range spectrum. Based on these observations, we construct a phenomenological model that gives the scalings of the amplitude of the fluctuations and the energy-dissipation rate as functions of the input parameters. We find good agreement between the numerical results and the predictions of the model.

  5. Towards large-scale plasma-assisted synthesis of nanowires

    NASA Astrophysics Data System (ADS)

    Cvelbar, U.

    2011-05-01

    Large quantities of nanomaterials, e.g. nanowires (NWs), are needed to overcome the high market price of nanomaterials and make nanotechnology widely available for general public use and applications to numerous devices. Therefore, there is an enormous need for new methods or routes for synthesis of those nanostructures. Here plasma technologies for synthesis of NWs, nanotubes, nanoparticles or other nanostructures might play a key role in the near future. This paper presents a three-dimensional problem of large-scale synthesis connected with the time, quantity and quality of nanostructures. Herein, four different plasma methods for NW synthesis are presented in contrast to other methods, e.g. thermal processes, chemical vapour deposition or wet chemical processes. The pros and cons are discussed in detail for the case of two metal oxides: iron oxide and zinc oxide NWs, which are important for many applications.

  6. Large scale instabilities and dynamics of the magnetotail plasma sheet

    SciTech Connect

    Birn, J.; Schindler, K.

    1986-01-01

    The stability properties of the magnetotail current sheet against large scale modes is reviewed in the framework of ideal MHD, resistive MHD, and collisionless Vlasov theory. It appears that the small deviations from a plane sheet pinch (in particular a magnetic field component normal to the sheet) are important to explain the transition of the tail from a quiet stable state to an unstable dynamic state. It is found that the tail is essentially stable in ideal MHD, but unstable in resistive MHD, while both stable and unstable configurations are found within collisionless theory. The results favor an interpretation where the onset of magnetotail dyanmics leading to a sudden thinning of the plasma sheet and the ejection of a plasmoid is caused by the onset of a collisionless instability that either directly leads to the growth of a collisionless tearing mode or via microscopic turbulence to the growth of a resistive mode. The actual onset conditions are not fully explored yet by rigorous methods. The onset may be triggered by local conditions as well as by boundary conditions at the ionosphere or at the magnetopause (resulting from solar wind conditions). 53 refs., 5 figs.

  7. Sheath overlap during very large scale plasma source ion implantation

    NASA Astrophysics Data System (ADS)

    Cluggish, B. P.; Munson, C. P.

    1998-12-01

    Measurements of plasma source ion implantation have been performed on a large target of complex geometry. The target consists of 1000 aluminum, automotive piston surrogates mounted on four racks; total surface area is over 16 m2. The four racks are positioned parallel to each other, 0.25 m apart, in an 8 m3 vacuum chamber. The racks of pistons are immersed in a capacitive radio frequency plasma, with an argon gas pressure of 20-65 mPa. Langmuir probe measurements indicate that the plasma density profile is highly nonuniform, due to particle losses to the racks of pistons. The plasma ions are implanted into the pistons by pulse biasing the workpiece to negative voltages as low as -18 kV for up to 20 μs. During the voltage pulse, the high-voltage sheaths from adjacent racks of pistons converge towards each other. At plasma densities less than 109 cm-3 the sheaths are observed to overlap. Measurements of the sheath overlap time are compared with standard analytic theory and with simulations run with a two-dimensional particle-in-cell code.

  8. Generation of large-scale equatorial F-region plasma depletions during geomagnetic storms: A review

    NASA Astrophysics Data System (ADS)

    Sahai, Y.; Fagundes, P.; Bittencourt, J.; Pimenta, A.

    All-sky imaging observations of the F-region OI 630 nm nightglow emission allow us to visualize large - scale equatorial plasma depletions, generally known as transequatorial plasma bubbles. These quasi north south direction aligned- ionospheric plasma depletions are o tical signatures of strong range type equatorialp spread-F. An extensive data base of the OI 630 nm emission all-sky imaging- observations has been obtained at Cachoeira Paulista (22.7o S, 45.0 o W; dip latitude ~16o S), Brazil, between the years 1987 and 2000. An analysis of these observations revealed that normally large-scale ionospheric plasma depletions do not occur during the months of May to August (southern winter) in the Brazilian sector. However, large-scale ionospheric plasma depletions during thes e months have been observed on several occasions in association with geomagnetic storms. In this paper, a detailed analysis of the events when large - scale ionospheric plasma depletions were initiated and evolved during magnetic disturbances will be present ed and discussed.

  9. Characteristics of plasma grid bias in large-scaled negative ion source

    SciTech Connect

    Kisaki, M.; Tsumori, K.; Ikeda, K.; Nakano, H.; Osakabe, M.; Nagaoka, K.; Takeiri, Y.; Kaneko, O.

    2014-02-15

    The electron density was measured at various bias voltages to understand how the plasma grid bias affects the electron near the plasma grid in large-scaled negative ion sources. It was found that the response of the electron to the bias voltage changes depending on negative ion production processes. The electron density remarkably decreases with increasing the bias voltage in the pure-volume plasma. On the other hand, the electron density depends on the bias voltage weakly in the Cs-seeded plasma. In addition, it was observed that the response of the co-extracted electron current to the bias voltage has similar trend to that of the electron density.

  10. Three Dimensional Dynamics of Magnetic Reconnection in Large-Scale Pair Plasmas

    NASA Astrophysics Data System (ADS)

    Yin, L.; Daughton, W.; Albright, B. J.; Bowers, K. J.; Karimabad, H.; Roytershteyn, V.

    2009-05-01

    Using the largest three dimensional particle-in-cell simulations to date, collisionless magnetic reconnection in large-scale electron-positron plasmas without a guide field is shown to involve complex interaction of tearing and kink modes. The reconnection onset is patchy and occurs at multiple sites which self-organize to form a single, large diffusion region. The diffusion region further expands in both outflow direction and current direction and become unstable to secondary kinking and formation of "plasmoid-rope" structures. The secondary kink leads to folding of the reconnection current layer, while plasmoid ropes at times follow the folding of the current layer. The interplay among these secondary instabilities plays a key role in controlling the time dependent reconnection rate in large-scale systems. These dynamics found in collisionless reconnection are compared with those in the collisional regime.

  11. Three Dimensional Dynamics of Collisionless Magnetic Reconnection in Large-Scale Pair Plasmas

    NASA Astrophysics Data System (ADS)

    Yin, L.; Daughton, W.; Karimabadi, H.; Albright, B. J.; Bowers, K. J.; Margulies, J.

    2008-12-01

    Using the largest three dimensional particle-in-cell simulations to date, collisionless magnetic reconnection in large-scale electron-positron plasmas without a guide field is shown to involve complex interaction of tearing and kink modes. The reconnection onset is patchy and occurs at multiple sites which self-organize to form a single, large diffusion region. There is a basic tendency for the diffusion region to further elongate in the outflow direction and become unstable to secondary kinking and formation of "plasmoid-rope" structures with finite extent in the current direction. The secondary kink leads to folding of the reconnection current layer, while plasmoid ropes at times follow the folding of the current layer. The interplay among these secondary instabilities plays a key role in controlling the time dependent reconnection rate in large-scale systems.

  12. Advanced kinetic plasma model implementation for new large-scale investigations

    NASA Astrophysics Data System (ADS)

    Reddell, Noah; Shumlak, Uri

    2013-10-01

    A kinetic plasma model for of one or more particle species described by the Vlasov equation and coupled to fully dynamic electromagnetic forces is presented. The model is implemented as evolving continuous PDF (probability density function) in particle phase space (position-velocity) as opposed to particle-in-cell (PIC) methods which discretely sample the PDF. A new boundary condition for the truncated velocity-space edge, motivated by physical properties of the PDF tail, is introduced. The hyperbolic model is evolved using the discontinuous Galerkin numerical method, conserving system mass, momentum, and energy - an advantage compared to PIC. Simulations of two- to six-dimensional phase space are computationally expensive. To maximize performance and scaling to large simulations, a new framework, WARPM, has been developed for many-core (e.g. GPU) computing architectures. WARPM supports both multi-fluid and continuum kinetic plasma models as coupled hyperbolic systems with nearest neighbor predictable communication. Exemplary physics results and computational performance are presented.

  13. Properties of large scale plasma flow during the early stage of the plasmaspheric refilling

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Craven, P.; Torr, D. G.; Richards, P. G.

    1990-01-01

    The objective is to better characterize the macroscopic properties of the interhemisphere plasma flow by solving a more complete set of hydrodynamic equations than that solved previously. Specifically, the ion continuity, momentum and energy equations were solved for the plasma flow along the closed magnetic field lines. During the initial stage of the supersonic outflow in the equatorial region, the ions cool substantially. Using the hydrodynamic model for the large-scale plasma flow, the dynamics of shocks was examined which form in the geomagnetic flux tubes during the early stages of refilling. These shocks are more like those forming in neutral gases than the electrostatic shocks driven by microinstabilities involving ion-ion interaction. Therefore, the shocks seen in the hydrodynamic model are termed as hydrodynamic shocks. Such shocks are generally unsteady and therefore the usual shock jump conditions given by Rankine-Hugoniot relations are not strictly applicable to them. The density, flow velocity and temperature structures associated with the shocks are examined for both asymmetrical and symmetrical flows. In the asymmetrical flow the outflow from one of two conjugate ionospheres is dominant. On the other hand, in the symmetrical case outflows from the two ionospheric sources are identical. Both cases are treated by a two-stream model. In the late type of flow, the early-time refilling shows a relaxation type of oscillation, which is driven by the large-scale interactions between the two identical streams. After this early stage, the resulting temperature structure shows some interesting features. In the equatorial region the streams are isothermal, but in the off-equatorial regions the streams have quite different temperatures, and also densities and flow velocities. The dense and slow stream is found to be warmer than the low-density fast stream. In the late stage of refilling, the temperature is found to steadily increase from the conjugate

  14. Self-organization of the large-scale planetary and plasma drift vortices.

    PubMed

    Nezlin, Mikhail V.; Chernikov, Gennady P.; Rylov, Andrey Yu.; Titishov, Kirill B.

    1996-09-01

    This paper is a semi-review. A new understanding of the self-organization mechanism of solitary (i.e., long-lived and, in this sense, soliton-like) large-scale vortices in geophysical fluid dynamics, as well as that of drift vortices in the magnetized plasma is discussed. This understanding differs from that described in a review paper by Nezlin [Chaos 4, 187-202 (1994)]. Earlier it was believed that formation of the solitary Rossby (and plasma drift) vortices was a result of equilibrium between wave dispersion and KdV-type nonlinearity. Under the influence of experimental data obtained by our team [M. V. Nezlin and E. N. Snezhkin, Rossby Vortices, Spiral Structures, Solitons (Springer-Verlag, Heidelberg, 1993)], it became obvious that the self-organization of the structures inevitably includes an essential effect of other nonlinearities; first, that presented by the Jacobian in the equations. (We replace the term "Rossby soliton" by the more exact one "the Rossby solitary vortex.") It must be noted from the very beginning that the term "self-organization" is used mainly in context with an explanation which factors (dispersion and nonlinearities of different kind) condition formation of the solitary (stable, long-lived) Rossby structures. Although, the experimental fact (see below) that the size of solitary vortices turns out to be close to the Rossby-Obukhov radius, independently of the size of the vortex local source, calls to mind the formation of an attractor. In essence, the Rossby solitary vortex self-organization process (although, only for the case of anticyclones) was described by Nycander and Sutyrin [Dyn. Atmos. Oceans 16, 473-498 (1992)]. Unfortunately, however, the authors did not use the term "self-organization." Our description, being in accord with Nycander and Sutyrin, relates not only to anticyclones, but also to anticyclones and cyclones. Second, a description of the experimental discovery of "anomalous" cyclonic-anticyclonic asymmetry is given

  15. X-ray imaging of uniform large scale-length plasmas created from gas-filled targets on Nova

    SciTech Connect

    Kalantar, D.H.; MacGowan, B.J.; Bernat, T.P.

    1994-05-01

    We report on the production and characterization of large scale-length plasmas created by illuminating gas-filled thin-walled balloon-like targets using the Nova laser. The targets consisted of a 4--5000 {angstrom} skin surrounding 1 atm of neopentane which when ionized becomes a plasma with 10{sup 21} electrons/cm{sup 3}. Results are presented from x-ray imaging used to evaluate the uniformity of the plasma. The most uniform plasmas were produced by illuminating the target with large converging beams that overlapped to cover most of the surface of the gasbag. An alternate focus geometry using small beam spots resulted in a less uniform plasma with low density holes in it.

  16. Simultaneous excitation of large-scale geomagnetic field fluctuations and plasma density irregularities by powerful radio waves

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Kuo, S. P.

    1985-01-01

    The physical mechanism of thermal filamentation instability of radio waves whose frequencies can be as low as in the VLF band and as high as in the SHF band are investigated. This instability can excite large-scale magnetic and plasma density fluctuations simultaneously in the ionosphere and magnetosphere. Relevant experiments are reviewed in terms of this instability and other mechanisms.

  17. Evolution of large-scale plasma structures in comets: Kinematics and physics

    NASA Technical Reports Server (NTRS)

    Brandt, John C.

    1993-01-01

    Cometary and solar wind data from December 1985 through April 1986 are presented for the purpose of determining the solar wind conditions associated with comet plasma tail disconnection events (DE's). The cometary data are from The International Halley Watch Atlas of Large-Scale Phenomena (Brandt, Niedner, and Rahe, 1992). In addition, we present the kinematic analysis of 4 DE's, those of Dec. 13.5 and 31.2, 1985, and Feb. 21.7 and 28.7, 1986. The circumstances of these DE's clearly illustrate the need to analyze DE's in groups. In situ solar wind measurements from IMP-8, ICE, and PVO were used to construct the variation of solar wind speed, density, and dynamic pressure during this interval. Data from these same spacecraft plus Vega-1 were used to determine the time of 48 current sheet crossings. These data were fitted to heliospheric current sheet curves extrapolated from the corona into the heliosphere in order to determine the best-fit source surface radius for each Carrington rotation. Comparison of the solar wind conditions and 16 DE's in Halley's comet (the four DE's discussed in this paper and 12 DE's in the literature) leaves little doubt that DE's are associated primarily with crossings of the heliospheric current sheet and apparently not with any other property of the solar wind. If we assume that there is a single or primary physical mechanism and that Halley's DE's are representative, efforts at simulation should concentrate on conditions at current sheet crossings. The mechanisms consistent with this result are sunward magnetic reconnection and tailward magnetic reconnection, if tailward reconnection can be triggered by the sector boundary crossing.

  18. Fabrication and testing of gas-filled targets for large-scale plasma experiments on nova

    SciTech Connect

    Stone, G.F.; Rivers, C.J.; Spragge, M.R.; Wallace, R.J.

    1996-06-01

    The proposed next-generation ICF facility, the National Ignition Facility (NIF) is designed to produce energy gain from x-ray heated {open_quotes}indirect-drive{close_quotes} fuel capsules. For indirect-drive targets, laser light heats the inside of the Au hohlraum wall and produces x rays which in turn heat and implode the capsule to produce fusion conditions in the fuel. Unlike Nova targets, in NIF-scale targets laser light will propagate through several millimeters of gas, producing a plasma, before impinging upon the Au hohlraum wall. The purpose of the gas-produced plasma is to provide sufficient pressure to keep the radiating Au surface from expanding excessively into the hohlraum cavity. Excessive expansion of the Au wall interacts with the laser pulse and degrades the drive symmetry of the capsule implosion. The authors have begun an experimental campaign on the Nova laser to study the effect of hohlraum gas on both laser-plasma interaction and implosion symmetry. In their current NIF target design, the calculated plasma electron temperature is T{sub e} {approx} 3 keV and the electron density is N{sub e} {approx} 10{sup 21}cm{sup {minus}3}.

  19. Ionospheric plasma flow over large high-voltage space platforms. I - Ion-plasma-time scale interactions of a plate at zero angle of attack. II - The formation and structure of plasma wake

    NASA Technical Reports Server (NTRS)

    Wang, J.; Hastings, D. E.

    1992-01-01

    The paper presents the theory and particle simulation results for the ionospheric plasma flow over a large high-voltage space platform at a zero angle of attack and at a large angle of attack. Emphasis is placed on the structures in the large, high-voltage regime and the transient plasma response on the ion-plasma time scale. Special consideration is given to the transient formation of the space-charge wake and its steady-state structure.

  20. Spatial Structure of Large-Scale Plasma Density Perturbations HF-Induced in the Ionospheric F 2 Region

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Komrakov, G. P.; Glukhov, Ya. V.; Andreeva, E. S.; Kunitsyn, V. E.; Kurbatov, G. A.

    2016-07-01

    We consider the experimental results obtained by studying the large-scale structure of the HF-disturbed ionospheric region. The experiments were performed using the SURA heating facility. The disturbed ionospheric region was sounded by signals radiated by GPS navigation satellite beacons as well as by signals of low-orbit satellites (radio tomography). The results of the experiments show that large-scale plasma density perturbations induced at altitudes higher than the F2 layer maximum can contribute significantly to the measured variations of the total electron density and can, with a certain arrangement of the reception points, be measured by the GPS sounding method.

  1. Scattering of electromagnetic waves by vortex density structures associated with interchange instability: Analytical and large scale plasma simulation results

    SciTech Connect

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.

    2014-05-15

    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.

  2. Ionospheric plasma disturbances generated by naturally occurring large-scale anomalous heat sources

    NASA Astrophysics Data System (ADS)

    Pradipta, Rezy; Lee, Min-Chang; Coster, Anthea J.; Tepley, Craig A.; Sulzer, Michael P.; Gonzalez, Sixto A.

    2017-04-01

    We report the findings from our investigation on the possibility of large-scale anomalous thermal gradients to generate acoustic-gravity waves (AGWs) and traveling ionospheric disturbances (TIDs). In particular, here we consider the case of summer 2006 North American heat wave event as a concrete example of such large-scale natural thermal gradients. This special scenario of AGW/TID generation was formulated based on the results of our experiments at the Arecibo Observatory in July 2006, followed by a systematic monitoring/surveillance of total electron content (TEC) fluctuations over North America in 2005-2007 using the MIT Haystack Observatory's Madrigal database. The data from our Arecibo experiments indicate a continual occurrence of intense AGW/TID over the Caribbean on 21-24 July 2006, and the Madrigal TEC data analysis shows that the overall level of TID activity over North America had increased by ∼0.2 TECU during the summer 2006 heat wave event. Our proposed scenario is in agreement with these empirical observations, and is generally consistent with a number of past ionospheric HF heating experiments related to AGW/TID generation.

  3. Quenching of the beam-plasma instability by 3-D spectra of large scale density fluctuations

    NASA Technical Reports Server (NTRS)

    Muschietti, L.; Goldman, M. V.; Newman, D.

    1984-01-01

    A model is presented to explain the highly variable yet low level of Langmuir waves measured in situ by spacecraft when electron beams associated with Type III solar bursts are passing by; the low level of excited waves allows the propagation of such streams from the Sun to well past 1 AU without catastrophic energy losses. The model is based, first, on the existence of large scale density fluctuations that are able to efficiently diffuse small k beam unstable Langmuir waves in phase space, and, second, on the presence of a significantly isotropic nonthermal tail in the distribution function of the background electron population, which is capable of stabilizing larger k modes. The strength of the model lies in its ability to predict various levels of Langmuir waves depending on the parameters. This feature is consistent with the high variability actually observed in the measurements.

  4. The solar wind structure that caused a large-scale disturbance of the plasma tail of comet Austin

    NASA Technical Reports Server (NTRS)

    Kozuka, Yukio; Konno, Ichishiro; Saito, Takao; Numazawa, Shigemi

    1992-01-01

    The plasma tail of Comet Austin (1989c1) showed remarkable disturbances because of the solar maximum periods and its orbit. Figure 1 shows photographs of Comet Austin taken in Shibata, Japan, on 29 Apr. 1990 UT, during about 20 minutes with the exposure times of 90 to 120 s. There are two main features in the disturbance; one is many bowed structures, which seem to move tailwards; and the other is a large-scale wavy structure. The bowed structures can be interpreted as arcade structures brushing the surface of both sides of the cometary plasma surrounding the nucleus. We identified thirteen structures of the arcades from each of the five photographs and calculated the relation between the distance of each structure from the cometary nucleus, chi, and the velocity, upsilon. The result is shown. This indicates that the velocity of the structures increases with distance. This is consistent with the result obtained from the observation at the Kiso Observatory.

  5. Large-Scale Mini-Magnetosphere Plasma Propulsion (M2P2) Experiments

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Slough, J.; Ziemba, T.; Euripides, P.; Adrian, M. L.; Gallagher, D.; Craven, P.; Tomlinson, W.; Cravens, J.; Burch, J.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Mini-Magnetosphere Plasma Propulsion (M2P2) is an innovative plasma propulsion system that has the potential to propel spacecraft at unprecedented speeds of 50 to 80 km per second with a low-power requirement of approx. 1 kW per 100 kg of payload and approx. 1 kg of neutral gas [fuel] consumption per day of acceleration. Acceleration periods from several days to a few months are envisioned. High specific impulse and efficiency are achieved through coupling of the spacecraft to the 400 km per second solar wind through an artificial magnetosphere. The mini-magnetosphere or inflated magnetic bubble is produced by the injection of cold dense plasma into a spacecraft-generated magnetic field envelope. Magnetic bubble inflation is driven by electromagnetic processes thereby avoiding the material and deployment problems faced by mechanical solar sail designs, Here, we present the theoretical design of M2P2 as well as initial results from experimental testing of an M2P2 prototype demonstrating: 1) inflation of the dipole magnetic field geometry through the internal injection of cold plasma; and 2) deflection of and artificial solar wind by the prototype M2P2 system. In addition, we present plans for direct laboratory measurement of thrust imparted to a prototype M2P2 by an artificial solar wind during the summer of 2001.

  6. Large-Scale Mini-Magnetosphere Plasma Propulsion (M2P2) Experiments

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Slough, J.; Ziemba, T.; Euripides, P.; Gallagher, D.; Craven, P.; Adrian, M. L.; Tomlinson, W.; Cravens, J.; Burch, J.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Mini-Magnetosphere Plasma Propulsion (M2P2) is an innovative plasma propulsion system that has the potential to propel spacecraft at unprecedented speeds of 50 to 80 km/s, with a low power requirement of approx. 1 kW per 100 kg of payload and -1 kg of neutral gas [fuel] consumption per day of acceleration. Acceleration periods from several days to a few months are envisioned. High specific impulse and efficiency are achieved through coupling of the spacecraft to the 400 km/s. solar wind through an artificial magnetosphere. The mini-magnetosphere or inflated magnetic bubble is produced by the injection of cold dense plasma into a spacecraft-generated magnetic field envelope. Magnetic bubble inflation is driven by electromagnetic processes thereby avoiding the material and deployment problems faced by mechanical solar sail designs. Here, we present the theoretical design of M2P2 as well as initial results from experimental testing of an M2P2 prototype demonstrating: 1) inflation of the dipole magnetic field geometry through the internal injection of cold plasma; and 2) deflection of and artificial solar wind by the prototype M2P2 system. In addition, we present plans for direct laboratory measurement of thrust imparted to a prototype M2P2 by an artificial solar wind during the summer of 2001.

  7. Physics of the interaction of ultra intense laser pulses with cold collisional plasma using large scale kinetic simulations

    SciTech Connect

    Héron, A.; Adam, J. C.

    2015-07-15

    We present a set of 2D collisional particle-in-cell simulations of the interaction of ultra-intense laser pulses with over-dense cold collisional plasmas. The size of these simulations is about 100 times as large as those previously published. This allows studying the transport of energetic particles on time scale of the order of 400 fs without perturbations due to the influence of boundary effects and performing a very detailed analysis of the physics of the transport. We confirm the existence of a threshold in intensity close to the relativistic threshold above which the beam of energetic particles diverges when it penetrates the cold plasma. We also study the applicability of Ohm's law to compute the electric field, which is the method commonly used in hybrid codes. The heating of the cold plasma is then studied and we show that half of the heating is anomalous, i.e., not given by standard Joule effect. We discuss the previously published results in the light of these new simulations.

  8. Large-scale molecular dynamics simulations of dense plasmas: The Cimarron Project

    NASA Astrophysics Data System (ADS)

    Graziani, Frank R.; Batista, Victor S.; Benedict, Lorin X.; Castor, John I.; Chen, Hui; Chen, Sophia N.; Fichtl, Chris A.; Glosli, James N.; Grabowski, Paul E.; Graf, Alexander T.; Hau-Riege, Stefan P.; Hazi, Andrew U.; Khairallah, Saad A.; Krauss, Liam; Langdon, A. Bruce; London, Richard A.; Markmann, Andreas; Murillo, Michael S.; Richards, David F.; Scott, Howard A.; Shepherd, Ronnie; Stanton, Liam G.; Streitz, Fred H.; Surh, Michael P.; Weisheit, Jon C.; Whitley, Heather D.

    2012-03-01

    We describe the status of a new time-dependent simulation capability for dense plasmas. The backbone of this multi-institutional effort - the Cimarron Project - is the massively parallel molecular dynamics (MD) code "ddcMD," developed at Lawrence Livermore National Laboratory. The project's focus is material conditions such as exist in inertial confinement fusion experiments, and in many stellar interiors: high temperatures, high densities, significant electromagnetic fields, mixtures of high- and low- Z elements, and non-Maxwellian particle distributions. Of particular importance is our ability to incorporate into this classical MD code key atomic, radiative, and nuclear processes, so that their interacting effects under non-ideal plasma conditions can be investigated. This paper summarizes progress in computational methodology, discusses strengths and weaknesses of quantum statistical potentials as effective interactions for MD, explains the model used for quantum events possibly occurring in a collision, describes two new experimental efforts that play a central role in our validation work, highlights some significant results obtained to date, outlines concepts now being explored to deal more efficiently with the very disparate dynamical timescales that arise in fusion plasmas, and provides a careful comparison of quantum effects on electron trajectories predicted by more elaborate dynamical methods.

  9. Modeling the dynamics of a plasma bulge with a high specific energy in the upper atmosphere. 2. Numerical simulation and physical features of a large-scale plasma flow at its late development stage: A review

    NASA Astrophysics Data System (ADS)

    Stupitsky, E. L.; Kholodov, A. S.

    2012-09-01

    The results of three-dimensional calculations of a plasma flow caused by a cosmic nuclear explosion, performed in an MHD approximation, are presented. The main regularities and specific features of the development of a large-scale plasma flow have been analyzed for a later stage (up to several hundreds of seconds) depending on the altitude and plasma bulge energy.

  10. Large area plasma source

    NASA Technical Reports Server (NTRS)

    Foster, John (Inventor); Patterson, Michael (Inventor)

    2008-01-01

    An all permanent magnet Electron Cyclotron Resonance, large diameter (e.g., 40 cm) plasma source suitable for ion/plasma processing or electric propulsion, is capable of producing uniform ion current densities at its exit plane at very low power (e.g., below 200 W), and is electrodeless to avoid sputtering or contamination issues. Microwave input power is efficiently coupled with an ionizing gas without using a dielectric microwave window and without developing a throat plasma by providing a ferromagnetic cylindrical chamber wall with a conical end narrowing to an axial entrance hole for microwaves supplied on-axis from an open-ended waveguide. Permanent magnet rings are attached inside the wall with alternating polarities against the wall. An entrance magnet ring surrounding the entrance hole has a ferromagnetic pole piece that extends into the chamber from the entrance hole to a continuing second face that extends radially across an inner pole of the entrance magnet ring.

  11. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    NASA Astrophysics Data System (ADS)

    Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

    2014-01-01

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  12. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    SciTech Connect

    Li, Lee Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

    2014-01-14

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  13. Optical measurements of a large-scale laboratory Beam Plasma Discharge (BPD)

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Mantjoukis, G.; Leinbach, F. H.; Hallinan, T.

    1983-01-01

    Optical emission measurements provided information on the spatial distribution of energetic (primary and suprathermal) electrons producing the emissions; power dissipation during beam transit of the system; and modifications of the primary beam velocity distribution. The measurements were carried out for BPD's produced in a very large vacuum chamber using a 391.4 nm scanning photometer and total light (red sensitive) TV systems. Results for conditions Eb 500 to 2000 V, injection pitch angle 0 to 75 deg, and neutral density are presented. The typical power loss in ionization in transit of the 20 m pathlength during BPD is from 3 to 10% of the input power, an order of magnitude greater than attributable to collisional ionization alone. Differences between rocket observations and the laboratory results are noted.

  14. State-of-the-art for large area high resolution gray scale and full color AC plasma flat panel displays

    NASA Technical Reports Server (NTRS)

    Stoller, Ray A.; Wedding, Donald K.; Friedman, Peter S.

    1993-01-01

    A development status evaluation is presented for gas plasma display technology, noting how tradeoffs among the parameters of size, resolution, speed, portability, color, and image quality can yield cost-effective solutions for medical imaging, CAD, teleconferencing, multimedia, and both civil and military applications. Attention is given to plasma-based large-area displays' suitability for radar, sonar, and IR, due to their lack of EM susceptibility. Both monochrome and color displays are available.

  15. Large-scale synthesis of uniform hexagonal boron nitride films by plasma-enhanced atomic layer deposition

    PubMed Central

    Park, Hamin; Kim, Tae Keun; Cho, Sung Woo; Jang, Hong Seok; Lee, Sang Ick; Choi, Sung-Yool

    2017-01-01

    Hexagonal boron nitride (h-BN) has been previously manufactured using mechanical exfoliation and chemical vapor deposition methods, which make the large-scale synthesis of uniform h-BN very challenging. In this study, we produced highly uniform and scalable h-BN films by plasma-enhanced atomic layer deposition, which were characterized by various techniques including atomic force microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. The film composition studied by X-ray photoelectron spectroscopy and Auger electron spectroscopy corresponded to a B:N stoichiometric ratio close to 1:1, and the band-gap value (5.65 eV) obtained by electron energy loss spectroscopy was consistent with the dielectric properties. The h-BN-containing capacitors were characterized by highly uniform properties, a reasonable dielectric constant (3), and low leakage current density, while graphene on h-BN substrates exhibited enhanced electrical performance such as the high carrier mobility and neutral Dirac voltage, which resulted from the low density of charged impurities on the h-BN surface. PMID:28054603

  16. Large-scale synthesis of uniform hexagonal boron nitride films by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Park, Hamin; Kim, Tae Keun; Cho, Sung Woo; Jang, Hong Seok; Lee, Sang Ick; Choi, Sung-Yool

    2017-01-01

    Hexagonal boron nitride (h-BN) has been previously manufactured using mechanical exfoliation and chemical vapor deposition methods, which make the large-scale synthesis of uniform h-BN very challenging. In this study, we produced highly uniform and scalable h-BN films by plasma-enhanced atomic layer deposition, which were characterized by various techniques including atomic force microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. The film composition studied by X-ray photoelectron spectroscopy and Auger electron spectroscopy corresponded to a B:N stoichiometric ratio close to 1:1, and the band-gap value (5.65 eV) obtained by electron energy loss spectroscopy was consistent with the dielectric properties. The h-BN-containing capacitors were characterized by highly uniform properties, a reasonable dielectric constant (3), and low leakage current density, while graphene on h-BN substrates exhibited enhanced electrical performance such as the high carrier mobility and neutral Dirac voltage, which resulted from the low density of charged impurities on the h-BN surface.

  17. Large scale dynamic systems

    NASA Technical Reports Server (NTRS)

    Doolin, B. F.

    1975-01-01

    Classes of large scale dynamic systems were discussed in the context of modern control theory. Specific examples discussed were in the technical fields of aeronautics, water resources and electric power.

  18. Observations of Reduced Electron Gyro-scale Fluctuations in National Spherical Torus Experiment H-mode Plasmas with Large E × B Flow Shear

    SciTech Connect

    Smith, D. R.; Kaye, S. M.; Lee, W.; Mazzucato, E.; Park, H. K.; Bell, R. E.; Domier, C. W.; LeBlanc, B. P.; Levinton, F. M.; Luhmann, Jr., N. C.; Menard, J. E.; Yu, H.

    2009-02-13

    Electron gyro-scale fluctuation measurements in National Spherical Torus Experiment (NSTX) H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temper- ature gradient (ETG) turbulence. Large toroidal rotation in NSTX plasmas with neutral beam injection generates E × B flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the E × B flow shear rate exceeds ETG linear growth rates. The observations indicate E × B flow shear can be an effective suppression mechanism for ETG turbulence.

  19. Study of Large-Scale Wave Structure and Development of Equatorial Plasma Bubbles Using the C/NOFS Satellite

    DTIC Science & Technology

    2012-10-31

    include Kwajalein and Guam. The scientific value of the Pacific cluster is enhanced by ionograms being collected with three ionosondes (Kwajalein, Pohnpei...R.T., Multi-reflected echoes: Another ionogram signature of large-scale wave structure, Geophys. Res. Lett., 36, L01102, doi:10.1029/2008GL036221...Geophys. Res. Lett., 38, L20102, doi:10.1029/2011GL049173, 2011. Thampi, S.V., R. Tsunoda, L. Jose, and T.K. Pant, Ionogram signatures of large-scale

  20. Large-Scale Disasters

    NASA Astrophysics Data System (ADS)

    Gad-El-Hak, Mohamed

    "Extreme" events - including climatic events, such as hurricanes, tornadoes, and drought - can cause massive disruption to society, including large death tolls and property damage in the billions of dollars. Events in recent years have shown the importance of being prepared and that countries need to work together to help alleviate the resulting pain and suffering. This volume presents a review of the broad research field of large-scale disasters. It establishes a common framework for predicting, controlling and managing both manmade and natural disasters. There is a particular focus on events caused by weather and climate change. Other topics include air pollution, tsunamis, disaster modeling, the use of remote sensing and the logistics of disaster management. It will appeal to scientists, engineers, first responders and health-care professionals, in addition to graduate students and researchers who have an interest in the prediction, prevention or mitigation of large-scale disasters.

  1. The sources of super-high energetic electron at relativistic circularly-polarized laser-solid interactions in the presence of large scale pre-plasmas

    NASA Astrophysics Data System (ADS)

    Wu, D.; Krasheninnikov, S. I.; Luan, S. X.; Yu, W.

    2016-12-01

    The two stage electron acceleration model [Wu et al., Nucl. Fusion 57, 016007 (2017)] is extended to investigate the sources of super-hot electrons at intense circularly polarized (CP) laser solid interactions. It is found that in the presence of large scale pre-formed plasmas, super-high energetic electrons can be generated. For laser of intensity 1020 W /cm2 and pre-plasma of scale-length 10 μm , the cut-off energy of electrons by CP laser can be as high as 120 MeV compared with 100 MeV by linearly polarized laser. This unexpected acceleration can be also explained by the two-stage acceleration model. The envelop modulation of reflected CP laser is figured out, and a modified scaling law of the maximal-possible energy gain when including the modulation effect is obtained.

  2. Generation of large-scale, barrier-free diffuse plasmas in air at atmospheric pressure using array wire electrodes and nanosecond high-voltage pulses

    SciTech Connect

    Teng, Yun; Li, Lee Liu, Yun-Long; Liu, Lun; Liu, Minghai

    2014-10-15

    This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18 × 15 × 15 cm{sup 3}, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

  3. Generation of large-scale, barrier-free diffuse plasmas in air at atmospheric pressure using array wire electrodes and nanosecond high-voltage pulses

    NASA Astrophysics Data System (ADS)

    Teng, Yun; Li, Lee; Liu, Yun-Long; Liu, Lun; Liu, Minghai

    2014-10-01

    This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18 × 15 × 15 cm3, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

  4. In vitro Stability of Heat Shock Protein 27 in Serum and Plasma Under Different Pre-analytical Conditions: Implications for Large-Scale Clinical Studies

    PubMed Central

    Zimmermann, Matthias; Traxler, Denise; Simader, Elisabeth; Bekos, Christine; Dieplinger, Benjamin; Lainscak, Mitja; Ankersmit, Hendrik Jan

    2016-01-01

    The effects of storage temperatures, repeated freeze-thaw cycles, or delays in separating plasma or serum from blood samples are largely unknown for heat shock protein 27 (HSP27). We evaluated (1) the imprecision of the HSP27 assay used in this study; (2) the in vitro stability of HSP27 in blood samples stored at 4℃ for up to 6 hr with immediate and delayed serum/plasma separation from cells; and (3) the in vitro stability of HSP27 in blood samples stored at -80℃ after repeated freeze-thaw cycles. The ELISA to detect HSP27 in this study showed a within-run CV of <9% and a total CV of <15%. After 4-6 hr of storage at 4℃, HSP27 concentrations remained stable when using serum tubes irrespective of sample handling, but HSP27 concentrations decreased by 25-45% when using EDTA plasma tubes. Compared with baseline HSP27, one freeze-thaw cycle had no effect on serum concentrations. However, plasma concentrations increased by 3.1-fold after one freeze-thaw cycle and by 7.3-fold after five freeze-thaw cycles. In conclusion, serum is an appropriate biological sample type for use in epidemiological and large-scale clinical studies. PMID:27139608

  5. Large-scale inference of protein tissue origin in gram-positive sepsis plasma using quantitative targeted proteomics

    PubMed Central

    Malmström, Erik; Kilsgård, Ola; Hauri, Simon; Smeds, Emanuel; Herwald, Heiko; Malmström, Lars; Malmström, Johan

    2016-01-01

    The plasma proteome is highly dynamic and variable, composed of proteins derived from surrounding tissues and cells. To investigate the complex processes that control the composition of the plasma proteome, we developed a mass spectrometry-based proteomics strategy to infer the origin of proteins detected in murine plasma. The strategy relies on the construction of a comprehensive protein tissue atlas from cells and highly vascularized organs using shotgun mass spectrometry. The protein tissue atlas was transformed to a spectral library for highly reproducible quantification of tissue-specific proteins directly in plasma using SWATH-like data-independent mass spectrometry analysis. We show that the method can determine drastic changes of tissue-specific protein profiles in blood plasma from mouse animal models with sepsis. The strategy can be extended to several other species advancing our understanding of the complex processes that contribute to the plasma proteome dynamics. PMID:26732734

  6. Large-scale inference of protein tissue origin in gram-positive sepsis plasma using quantitative targeted proteomics.

    PubMed

    Malmström, Erik; Kilsgård, Ola; Hauri, Simon; Smeds, Emanuel; Herwald, Heiko; Malmström, Lars; Malmström, Johan

    2016-01-06

    The plasma proteome is highly dynamic and variable, composed of proteins derived from surrounding tissues and cells. To investigate the complex processes that control the composition of the plasma proteome, we developed a mass spectrometry-based proteomics strategy to infer the origin of proteins detected in murine plasma. The strategy relies on the construction of a comprehensive protein tissue atlas from cells and highly vascularized organs using shotgun mass spectrometry. The protein tissue atlas was transformed to a spectral library for highly reproducible quantification of tissue-specific proteins directly in plasma using SWATH-like data-independent mass spectrometry analysis. We show that the method can determine drastic changes of tissue-specific protein profiles in blood plasma from mouse animal models with sepsis. The strategy can be extended to several other species advancing our understanding of the complex processes that contribute to the plasma proteome dynamics.

  7. An interpretation of the large scale ionospheric magnetic fields and the altitude distribution of the ionospheric plasma on the dayside of Venus and Mars

    NASA Astrophysics Data System (ADS)

    Krymskii, A. M.

    Due to the sensitivity of the plasma scale height to the ability of the ionospheres of Venus and Mars to stand off the solar wind flow, as well as its sensitivity to the details of ionospheric plasma convection, the features of the magnetic field can manifest themselves in the plasma scale height. It is presently demonstrated that the scale height of the plasma is proportional to the neutral atmosphere scale height if the magnetic field pressure is low and the vertical magnetic field is small, as is typical for the 'overpressure' region where the solar wind pressure exceeds ionospheric thermal pressure. In other cases, diffusive equilibrium exists.

  8. Large scale traffic simulations

    SciTech Connect

    Nagel, K.; Barrett, C.L. |; Rickert, M. |

    1997-04-01

    Large scale microscopic (i.e. vehicle-based) traffic simulations pose high demands on computational speed in at least two application areas: (i) real-time traffic forecasting, and (ii) long-term planning applications (where repeated {open_quotes}looping{close_quotes} between the microsimulation and the simulated planning of individual person`s behavior is necessary). As a rough number, a real-time simulation of an area such as Los Angeles (ca. 1 million travellers) will need a computational speed of much higher than 1 million {open_quotes}particle{close_quotes} (= vehicle) updates per second. This paper reviews how this problem is approached in different projects and how these approaches are dependent both on the specific questions and on the prospective user community. The approaches reach from highly parallel and vectorizable, single-bit implementations on parallel supercomputers for Statistical Physics questions, via more realistic implementations on coupled workstations, to more complicated driving dynamics implemented again on parallel supercomputers. 45 refs., 9 figs., 1 tab.

  9. Large scale tracking algorithms

    SciTech Connect

    Hansen, Ross L.; Love, Joshua Alan; Melgaard, David Kennett; Karelitz, David B.; Pitts, Todd Alan; Zollweg, Joshua David; Anderson, Dylan Z.; Nandy, Prabal; Whitlow, Gary L.; Bender, Daniel A.; Byrne, Raymond Harry

    2015-01-01

    Low signal-to-noise data processing algorithms for improved detection, tracking, discrimination and situational threat assessment are a key research challenge. As sensor technologies progress, the number of pixels will increase signi cantly. This will result in increased resolution, which could improve object discrimination, but unfortunately, will also result in a significant increase in the number of potential targets to track. Many tracking techniques, like multi-hypothesis trackers, suffer from a combinatorial explosion as the number of potential targets increase. As the resolution increases, the phenomenology applied towards detection algorithms also changes. For low resolution sensors, "blob" tracking is the norm. For higher resolution data, additional information may be employed in the detection and classfication steps. The most challenging scenarios are those where the targets cannot be fully resolved, yet must be tracked and distinguished for neighboring closely spaced objects. Tracking vehicles in an urban environment is an example of such a challenging scenario. This report evaluates several potential tracking algorithms for large-scale tracking in an urban environment.

  10. Large amplitude relativistic plasma waves

    SciTech Connect

    Coffey, Timothy

    2010-05-15

    Relativistic, longitudinal plasma oscillations are studied for the case of a simple water bag distribution of electrons having cylindrical symmetry in momentum space with the axis of the cylinder parallel to the velocity of wave propagation. The plasma is required to obey the relativistic Vlasov-Poisson equations, and solutions are sought in the wave frame. An exact solution for the plasma density as a function of the electrostatic field is derived. The maximum electric field is presented in terms of an integral over the known density. It is shown that when the perpendicular momentum is neglected, the maximum electric field approaches infinity as the wave phase velocity approaches the speed of light. It is also shown that for any nonzero perpendicular momentum, the maximum electric field will remain finite as the wave phase velocity approaches the speed of light. The relationship to previously published solutions is discussed as is some recent controversy regarding the proper modeling of large amplitude relativistic plasma waves.

  11. The ion acoustic decay instability in a large scale, hot plasma relevant to direct drive laser fusion -- Application to a critical surface diagnostic. Final report

    SciTech Connect

    Mizuno, K.; DeGroot, J.S.; Drake, R.P.; Seka, W.; Craxton, R.S.; Estabrook, K.G.

    1996-08-01

    The authors have studied the ion acoustic decay instability in a large ({approximately} 1 mm) scale, hot ({approximately} 1 keV) plasma, which is relevant to a laser fusion reactor target. They have shown that the instability threshold is low. They have developed a novel collective Thomson scattering diagnostic at a 90{degree} scattering angle. The scattering is nonetheless coherent, because of the modest ratio of the frequency of the probe laser to that of the pump laser, such that even for such a large angle, (k{lambda}{sub De}){sup 2} is much less than one. With this system they have measured the electron plasma wave excited by the ion acoustic decay instability near the critical density (n{sub e} {approximately} 0.86 n{sub c}). This allows them to use the frequency of the detected wave to measure the electron temperature in the interaction region, obtaining a result reasonably close to that predicted by the SAGE computer code.

  12. X6.9-CLASS FLARE-INDUCED VERTICAL KINK OSCILLATIONS IN A LARGE-SCALE PLASMA CURTAIN AS OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Srivastava, A. K.; Goossens, M.

    2013-11-01

    We present rare observational evidence of vertical kink oscillations in a laminar and diffused large-scale plasma curtain as observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The X6.9-class flare in active region 11263 on 2011 August 9 induces a global large-scale disturbance that propagates in a narrow lane above the plasma curtain and creates a low density region that appears as a dimming in the observational image data. This large-scale propagating disturbance acts as a non-periodic driver that interacts asymmetrically and obliquely with the top of the plasma curtain and triggers the observed oscillations. In the deeper layers of the curtain, we find evidence of vertical kink oscillations with two periods (795 s and 530 s). On the magnetic surface of the curtain where the density is inhomogeneous due to coronal dimming, non-decaying vertical oscillations are also observed (period ≈ 763-896 s). We infer that the global large-scale disturbance triggers vertical kink oscillations in the deeper layers as well as on the surface of the large-scale plasma curtain. The properties of the excited waves strongly depend on the local plasma and magnetic field conditions.

  13. Very Large Scale Optimization

    NASA Technical Reports Server (NTRS)

    Vanderplaats, Garrett; Townsend, James C. (Technical Monitor)

    2002-01-01

    The purpose of this research under the NASA Small Business Innovative Research program was to develop algorithms and associated software to solve very large nonlinear, constrained optimization tasks. Key issues included efficiency, reliability, memory, and gradient calculation requirements. This report describes the general optimization problem, ten candidate methods, and detailed evaluations of four candidates. The algorithm chosen for final development is a modern recreation of a 1960s external penalty function method that uses very limited computer memory and computational time. Although of lower efficiency, the new method can solve problems orders of magnitude larger than current methods. The resulting BIGDOT software has been demonstrated on problems with 50,000 variables and about 50,000 active constraints. For unconstrained optimization, it has solved a problem in excess of 135,000 variables. The method includes a technique for solving discrete variable problems that finds a "good" design, although a theoretical optimum cannot be guaranteed. It is very scalable in that the number of function and gradient evaluations does not change significantly with increased problem size. Test cases are provided to demonstrate the efficiency and reliability of the methods and software.

  14. The ion acoustic decay instability, and anomalous laser light absorption for the OMEGA upgrade, large scale hot plasma application to a critical surface diagnostic, and instability at the quarter critical density. Final report

    SciTech Connect

    Mizuno, K.; DeGroot, J.S.; Seka, W.

    1996-11-01

    It is shown that laser light can be anomalously absorbed with a moderate intensity laster (I{lambda}{sup 2}{approx}10{sup 14} W/cm{sup 2}-{mu}m{sup 2}) in a large scale, laser produced plasma. The heating regime, which is characterized by a relatively weak instability in a large region, is different from the regime studied previously, which is characterized by a strong instability in a narrow region. The two dimensional geometrical effect (lateral heating) has an important consequence on the anomalous electron heating. The characteristics of the IADI, and the anomalous absorption of the laser light were studied in a large scale, hot plasma applicable to OMEGA upgrade plasma. These results are important for the diagnostic application of the IADI.

  15. Large-scale structural optimization

    NASA Technical Reports Server (NTRS)

    Sobieszczanski-Sobieski, J.

    1983-01-01

    Problems encountered by aerospace designers in attempting to optimize whole aircraft are discussed, along with possible solutions. Large scale optimization, as opposed to component-by-component optimization, is hindered by computational costs, software inflexibility, concentration on a single, rather than trade-off, design methodology and the incompatibility of large-scale optimization with single program, single computer methods. The software problem can be approached by placing the full analysis outside of the optimization loop. Full analysis is then performed only periodically. Problem-dependent software can be removed from the generic code using a systems programming technique, and then embody the definitions of design variables, objective function and design constraints. Trade-off algorithms can be used at the design points to obtain quantitative answers. Finally, decomposing the large-scale problem into independent subproblems allows systematic optimization of the problems by an organization of people and machines.

  16. Galaxy clustering on large scales.

    PubMed Central

    Efstathiou, G

    1993-01-01

    I describe some recent observations of large-scale structure in the galaxy distribution. The best constraints come from two-dimensional galaxy surveys and studies of angular correlation functions. Results from galaxy redshift surveys are much less precise but are consistent with the angular correlations, provided the distortions in mapping between real-space and redshift-space are relatively weak. The galaxy two-point correlation function, rich-cluster two-point correlation function, and galaxy-cluster cross-correlation function are all well described on large scales ( greater, similar 20h-1 Mpc, where the Hubble constant, H0 = 100h km.s-1.Mpc; 1 pc = 3.09 x 10(16) m) by the power spectrum of an initially scale-invariant, adiabatic, cold-dark-matter Universe with Gamma = Omegah approximately 0.2. I discuss how this fits in with the Cosmic Background Explorer (COBE) satellite detection of large-scale anisotropies in the microwave background radiation and other measures of large-scale structure in the Universe. PMID:11607400

  17. Spacecraft charging and plasma interaction implications for large space systems

    NASA Technical Reports Server (NTRS)

    Miller, E.; Stauber, M.; Rossi, M.; Fischbein, W.

    1978-01-01

    Specific discharge mechanisms, plasma interactions, and scale effects associated with very large spacecraft are studied. The large area, low density character, and extensive use of non-conducting materials is thought to have a major impact on the performance and survivability of many large space systems.

  18. Material design of plasma-enhanced chemical vapour deposition SiCH films for low-k cap layers in the further scaling of ultra-large-scale integrated devices-Cu interconnects.

    PubMed

    Shimizu, Hideharu; Nagano, Shuji; Uedono, Akira; Tajima, Nobuo; Momose, Takeshi; Shimogaki, Yukihiro

    2013-10-01

    Cap layers for Cu interconnects in ultra-large-scale integrated devices (ULSIs), with a low dielectric constant (k-value) and strong barrier properties against Cu and moisture diffusion, are required for the future further scaling of ULSIs. There is a trade-off, however, between reducing the k-value and maintaining strong barrier properties. Using quantum mechanical simulations and other theoretical computations, we have designed ideal dielectrics: SiCH films with Si-C2H4-Si networks. Such films were estimated to have low porosity and low k; thus they are the key to realizing a cap layer with a low k and strong barrier properties against diffusion. For fabricating these ideal SiCH films, we designed four novel precursors: isobutyl trimethylsilane, diisobutyl dimethylsilane, 1, 1-divinylsilacyclopentane and 5-silaspiro [4,4] noname, based on quantum chemical calculations, because such fabrication is difficult by controlling only the process conditions in plasma-enhanced chemical vapor deposition (PECVD) using conventional precursors. We demonstrated that SiCH films prepared using these newly designed precursors had large amounts of Si-C2H4-Si networks and strong barrier properties. The pore structure of these films was then analyzed by positron annihilation spectroscopy, revealing that these SiCH films actually had low porosity, as we designed. These results validate our material and precursor design concepts for developing a PECVD process capable of fabricating a low-k cap layer.

  19. Large scale cluster computing workshop

    SciTech Connect

    Dane Skow; Alan Silverman

    2002-12-23

    Recent revolutions in computer hardware and software technologies have paved the way for the large-scale deployment of clusters of commodity computers to address problems heretofore the domain of tightly coupled SMP processors. Near term projects within High Energy Physics and other computing communities will deploy clusters of scale 1000s of processors and be used by 100s to 1000s of independent users. This will expand the reach in both dimensions by an order of magnitude from the current successful production facilities. The goals of this workshop were: (1) to determine what tools exist which can scale up to the cluster sizes foreseen for the next generation of HENP experiments (several thousand nodes) and by implication to identify areas where some investment of money or effort is likely to be needed. (2) To compare and record experimences gained with such tools. (3) To produce a practical guide to all stages of planning, installing, building and operating a large computing cluster in HENP. (4) To identify and connect groups with similar interest within HENP and the larger clustering community.

  20. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.

    1991-01-01

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

  1. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

    1991-07-16

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

  2. Large-Scale Sequence Comparison.

    PubMed

    Lal, Devi; Verma, Mansi

    2017-01-01

    There are millions of sequences deposited in genomic databases, and it is an important task to categorize them according to their structural and functional roles. Sequence comparison is a prerequisite for proper categorization of both DNA and protein sequences, and helps in assigning a putative or hypothetical structure and function to a given sequence. There are various methods available for comparing sequences, alignment being first and foremost for sequences with a small number of base pairs as well as for large-scale genome comparison. Various tools are available for performing pairwise large sequence comparison. The best known tools either perform global alignment or generate local alignments between the two sequences. In this chapter we first provide basic information regarding sequence comparison. This is followed by the description of the PAM and BLOSUM matrices that form the basis of sequence comparison. We also give a practical overview of currently available methods such as BLAST and FASTA, followed by a description and overview of tools available for genome comparison including LAGAN, MumMER, BLASTZ, and AVID.

  3. Large-scale PACS implementation.

    PubMed

    Carrino, J A; Unkel, P J; Miller, I D; Bowser, C L; Freckleton, M W; Johnson, T G

    1998-08-01

    The transition to filmless radiology is a much more formidable task than making the request for proposal to purchase a (Picture Archiving and Communications System) PACS. The Department of Defense and the Veterans Administration have been pioneers in the transformation of medical diagnostic imaging to the electronic environment. Many civilian sites are expected to implement large-scale PACS in the next five to ten years. This presentation will related the empirical insights gleaned at our institution from a large-scale PACS implementation. Our PACS integration was introduced into a fully operational department (not a new hospital) in which work flow had to continue with minimal impact. Impediments to user acceptance will be addressed. The critical components of this enormous task will be discussed. The topics covered during this session will include issues such as phased implementation, DICOM (digital imaging and communications in medicine) standard-based interaction of devices, hospital information system (HIS)/radiology information system (RIS) interface, user approval, networking, workstation deployment and backup procedures. The presentation will make specific suggestions regarding the implementation team, operating instructions, quality control (QC), training and education. The concept of identifying key functional areas is relevant to transitioning the facility to be entirely on line. Special attention must be paid to specific functional areas such as the operating rooms and trauma rooms where the clinical requirements may not match the PACS capabilities. The printing of films may be necessary for certain circumstances. The integration of teleradiology and remote clinics into a PACS is a salient topic with respect to the overall role of the radiologists providing rapid consultation. A Web-based server allows a clinician to review images and reports on a desk-top (personal) computer and thus reduce the number of dedicated PACS review workstations. This session

  4. Large-Scale Information Systems

    SciTech Connect

    D. M. Nicol; H. R. Ammerlahn; M. E. Goldsby; M. M. Johnson; D. E. Rhodes; A. S. Yoshimura

    2000-12-01

    Large enterprises are ever more dependent on their Large-Scale Information Systems (LSLS), computer systems that are distinguished architecturally by distributed components--data sources, networks, computing engines, simulations, human-in-the-loop control and remote access stations. These systems provide such capabilities as workflow, data fusion and distributed database access. The Nuclear Weapons Complex (NWC) contains many examples of LSIS components, a fact that motivates this research. However, most LSIS in use grew up from collections of separate subsystems that were not designed to be components of an integrated system. For this reason, they are often difficult to analyze and control. The problem is made more difficult by the size of a typical system, its diversity of information sources, and the institutional complexities associated with its geographic distribution across the enterprise. Moreover, there is no integrated approach for analyzing or managing such systems. Indeed, integrated development of LSIS is an active area of academic research. This work developed such an approach by simulating the various components of the LSIS and allowing the simulated components to interact with real LSIS subsystems. This research demonstrated two benefits. First, applying it to a particular LSIS provided a thorough understanding of the interfaces between the system's components. Second, it demonstrated how more rapid and detailed answers could be obtained to questions significant to the enterprise by interacting with the relevant LSIS subsystems through simulated components designed with those questions in mind. In a final, added phase of the project, investigations were made on extending this research to wireless communication networks in support of telemetry applications.

  5. Large Scale Magnetostrictive Valve Actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  6. Large area atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  7. Space-plasma campaign on UCLA's Large Plasma Device (LAPD)

    NASA Astrophysics Data System (ADS)

    Koepke, M. E.; Finnegan, S. M.; Knudsen, D. J.; Vincena, S.

    2007-05-01

    Knudsen [JGR, 1996] describes a potential role for stationary Alfvén (StA) waves in auroral arcs' frequency dependence. Magnetized plasmas are predicted to support electromagnetic perturbations that are static in a fixed frame if there is uniform background plasma convection. These stationary waves should not be confused with standing waves that oscillate in time with a fixed, spatially varying envelope. Stationary waves have no time variation in the fixed frame. In the drifting frame, there is an apparent time dependence as plasma convects past fixed electromagnetic structures. We describe early results from an experimental campaign to reproduce in the lab the basic conditions necessary for the creation of StA waves, namely quasi-steady-state convection across magnetic field-aligned current channels. We show that an off-axis, fixed channel of electron current (and depleted density) is created in the Large Plasma Device Upgrade (LAPD) at UCLA, using a small, heated, oxide-coated electrode at one plasma-column end and we show that the larger plasma column rotates about its cylindrical axis from a radial electric field imposed by a special termination electrode on the same end. Initial experimentation with plasma-rotation-inducing termination electrodes began in May 2006 in the West Virginia Q Machine, leading to two designs that, in January 2007, were tested in LAPD. The radial profile of azimuthal velocity was consistent with predictions of rigid-body rotation. Current-channel experiments in LAPD, in August 2006, showed that inertial Alfvén waves could be concentrated in an off-axis channel of electron current and depleted plasma density. These experimental results will be presented and discussed. This research is supported by DOE and NSF.

  8. New Large Diameter RF Complex Plasma Device

    NASA Astrophysics Data System (ADS)

    Meyer, John; Nosenko, Volodymyr; Thomas, Hubertus

    2016-10-01

    The Complex Plasma Research Group at the German Aerospace Center (DLR) in Oberpfaffenhofen has built a new large diameter rf plasma setup for dusty plasma experiments. The vacuum chamber is a stainless steel cylinder 0.90 m in diameter and 0.34 m in height with ports for viewing and measurement. A 0.85 m diameter plate in about the center serves as a powered electrode (13.56 MHz) with the chamber walls as the ground. It is pumped on by one of two Oerlikon turbo pumps with a pumping rate of 1100 l/s or 270 l/s. Argon gas is admitted into the chamber by an MKS mass flow meter and pumping is regulated by a butterfly valve to set pressure for experiments. A manual dropper is used to insert dust into the plasma. The dust is illuminated horizontally by a 660 nm 100 mW laser sheet and viewed from above by a Photron FASTCAM 1024 PCI camera. A vertical laser sheet of 635 nm will be used for side imaging. So far, single-layer plasma crystals of up to 15000 particles have been suspended. The particle velocity fluctuation spectra were measured and from these, the particle charge and screening length were calculated. Future experiments will explore the system-size dependence of the plasma crystal properties.

  9. Scaling of asymmetric reconnection in compressible plasmas

    SciTech Connect

    Birn, J.; Borovsky, J. E.; Hesse, M.

    2010-05-15

    The scaling of the reconnection rate with external parameters is reconsidered for antiparallel reconnection in a single-fluid magnetohydrodynamic (MHD) model, allowing for compressibility as well as asymmetry between the plasmas and magnetic fields in the two inflow regions. The results show a modest dependence of the reconnection rate on the plasma beta (ratio of plasma to magnetic pressure) in the inflow regions and demonstrate the importance of the conversion of magnetic energy to enthalpy flux (that is, convected thermal energy) in the outflow regions. The conversion of incoming magnetic to outgoing thermal energy flux remains finite even in the limit of incompressibility, while the scaling of the reconnection rate obtained earlier [P. A. Cassak and M. A. Shay, Phys. Plasmas 14, 102114 (2007)] is recovered. The assumptions entering the scaling estimates are critically investigated on the basis of two-dimensional resistive MHD simulations, confirming and even strengthening the importance of the enthalpy flux in the outflow from the reconnection site.

  10. ArI/ArII laser induced fluorescence system for measurement of neutral and ion dynamics in a large scale helicon plasma

    NASA Astrophysics Data System (ADS)

    Kelly, R. F.; Meaney, K. D.; Gilmore, M.; Desjardins, T. R.; Zhang, Y.

    2016-11-01

    In order to investigate the role of both neutral and ion dynamics in large-scale helicon discharges, a laser induced fluorescence (LIF) system capable of measuring both ArI and ArII fluorescence using a single tunable laser is being developed. The system is based on a >250 mW solid state laser. For ArI measurements, the laser pumps the metastable (2P03/2)4s level to the (2P01/2)4p level using 696.7352 nm light, and fluorescence radiation from decay to the (2P01/2)4s level at 772.6333 nm is observed. For ArII, currently in development, the metastable (3P)3d 4F7/2 level will be pumped to the (3P)4p 4D07/2 level using 688.8511 nm, and decay fluorescence to the (3P)4s 4P5/2 level at 434.9285 nm measured. Here all wavelengths are in a vacuum.

  11. Dynamics of exploding plasmas in a large magnetized plasma

    SciTech Connect

    Niemann, C.; Gekelman, W.; Constantin, C. G.; Everson, E. T.; Schaeffer, D. B.; Clark, S. E.; Zylstra, A. B.; Pribyl, P.; Tripathi, S. K. P.; Bondarenko, A. S.; Winske, D.; Larson, D.; Glenzer, S. H.

    2013-01-15

    The dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma was investigated with magnetic flux probes and Langmuir probes. Debris-ions expanding at super-Alfvenic velocity (up to M{sub A}=1.5) expel the ambient magnetic field, creating a large (>20 cm) diamagnetic cavity. We observe a field compression of up to B/B{sub 0}=1.5 as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized by the magnetic piston and swept outside the bubble volume. Nonlinear shear-Alfven waves ({delta}B/B{sub 0}>25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave.

  12. Large-Scale Interlaboratory Study to Develop, Analytically Validate and Apply Highly Multiplexed, Quantitative Peptide Assays to Measure Cancer-Relevant Proteins in Plasma*

    PubMed Central

    Abbatiello, Susan E.; Schilling, Birgit; Mani, D. R.; Zimmerman, Lisa J.; Hall, Steven C.; MacLean, Brendan; Albertolle, Matthew; Allen, Simon; Burgess, Michael; Cusack, Michael P.; Gosh, Mousumi; Hedrick, Victoria; Held, Jason M.; Inerowicz, H. Dorota; Jackson, Angela; Keshishian, Hasmik; Kinsinger, Christopher R.; Lyssand, John; Makowski, Lee; Mesri, Mehdi; Rodriguez, Henry; Rudnick, Paul; Sadowski, Pawel; Sedransk, Nell; Shaddox, Kent; Skates, Stephen J.; Kuhn, Eric; Smith, Derek; Whiteaker, Jeffery R.; Whitwell, Corbin; Zhang, Shucha; Borchers, Christoph H.; Fisher, Susan J.; Gibson, Bradford W.; Liebler, Daniel C.; MacCoss, Michael J.; Neubert, Thomas A.; Paulovich, Amanda G.; Regnier, Fred E.; Tempst, Paul; Carr, Steven A.

    2015-01-01

    There is an increasing need in biology and clinical medicine to robustly and reliably measure tens to hundreds of peptides and proteins in clinical and biological samples with high sensitivity, specificity, reproducibility, and repeatability. Previously, we demonstrated that LC-MRM-MS with isotope dilution has suitable performance for quantitative measurements of small numbers of relatively abundant proteins in human plasma and that the resulting assays can be transferred across laboratories while maintaining high reproducibility and quantitative precision. Here, we significantly extend that earlier work, demonstrating that 11 laboratories using 14 LC-MS systems can develop, determine analytical figures of merit, and apply highly multiplexed MRM-MS assays targeting 125 peptides derived from 27 cancer-relevant proteins and seven control proteins to precisely and reproducibly measure the analytes in human plasma. To ensure consistent generation of high quality data, we incorporated a system suitability protocol (SSP) into our experimental design. The SSP enabled real-time monitoring of LC-MRM-MS performance during assay development and implementation, facilitating early detection and correction of chromatographic and instrumental problems. Low to subnanogram/ml sensitivity for proteins in plasma was achieved by one-step immunoaffinity depletion of 14 abundant plasma proteins prior to analysis. Median intra- and interlaboratory reproducibility was <20%, sufficient for most biological studies and candidate protein biomarker verification. Digestion recovery of peptides was assessed and quantitative accuracy improved using heavy-isotope-labeled versions of the proteins as internal standards. Using the highly multiplexed assay, participating laboratories were able to precisely and reproducibly determine the levels of a series of analytes in blinded samples used to simulate an interlaboratory clinical study of patient samples. Our study further establishes that LC

  13. Generation of large-scale magnetic fields by small-scale dynamo in shear flows

    DOE PAGES

    Squire, J.; Bhattacharjee, A.

    2015-10-20

    We propose a new mechanism for a turbulent mean-field dynamo in which the magnetic fluctuations resulting from a small-scale dynamo drive the generation of large-scale magnetic fields. This is in stark contrast to the common idea that small-scale magnetic fields should be harmful to large-scale dynamo action. These dynamos occur in the presence of a large-scale velocity shear and do not require net helicity, resulting from off-diagonal components of the turbulent resistivity tensor as the magnetic analogue of the "shear-current" effect. Furthermore, given the inevitable existence of nonhelical small-scale magnetic fields in turbulent plasmas, as well as the generic naturemore » of velocity shear, the suggested mechanism may help explain the generation of large-scale magnetic fields across a wide range of astrophysical objects.« less

  14. Generation of large-scale magnetic fields by small-scale dynamo in shear flows

    SciTech Connect

    Squire, J.; Bhattacharjee, A.

    2015-10-20

    We propose a new mechanism for a turbulent mean-field dynamo in which the magnetic fluctuations resulting from a small-scale dynamo drive the generation of large-scale magnetic fields. This is in stark contrast to the common idea that small-scale magnetic fields should be harmful to large-scale dynamo action. These dynamos occur in the presence of a large-scale velocity shear and do not require net helicity, resulting from off-diagonal components of the turbulent resistivity tensor as the magnetic analogue of the "shear-current" effect. Furthermore, given the inevitable existence of nonhelical small-scale magnetic fields in turbulent plasmas, as well as the generic nature of velocity shear, the suggested mechanism may help explain the generation of large-scale magnetic fields across a wide range of astrophysical objects.

  15. Large-scale Digitoxin Intoxication

    PubMed Central

    Lely, A. H.; Van Enter, C. H. J.

    1970-01-01

    Because of an error in the manufacture of digoxin tablets a large number of patients took tablets that contained 0·20 mg. of digitoxin and 0·05 mg. of digoxin instead of the prescribed 0·25 mg. of digoxin. The symptoms are described of 179 patients who took these tablets and suffered from digitalis intoxication. Of these patients, 125 had taken the faultily composed tablets for more than three weeks. In 48 patients 105 separate disturbances in rhythm or in atrioventricular conduction were observed on the electrocardiogram. Extreme fatigue and serious eye conditions were observed in 95% of the patients. Twelve patients had a transient psychosis. Extensive ophthalmological observations indicated that the visual complaints were most probably caused by a transient retrobulbar neuritis. PMID:5273245

  16. Large Scale Metal Additive Techniques Review

    SciTech Connect

    Nycz, Andrzej; Adediran, Adeola I; Noakes, Mark W; Love, Lonnie J

    2016-01-01

    In recent years additive manufacturing made long strides toward becoming a main stream production technology. Particularly strong progress has been made in large-scale polymer deposition. However, large scale metal additive has not yet reached parity with large scale polymer. This paper is a review study of the metal additive techniques in the context of building large structures. Current commercial devices are capable of printing metal parts on the order of several cubic feet compared to hundreds of cubic feet for the polymer side. In order to follow the polymer progress path several factors are considered: potential to scale, economy, environment friendliness, material properties, feedstock availability, robustness of the process, quality and accuracy, potential for defects, and post processing as well as potential applications. This paper focuses on current state of art of large scale metal additive technology with a focus on expanding the geometric limits.

  17. Analysis of rapid increase in the plasma density during the ramp-up phase in a radio frequency negative ion source by large-scale particle simulation.

    PubMed

    Yasumoto, M; Ohta, M; Kawamura, Y; Hatayama, A

    2014-02-01

    Numerical simulations become useful for the developing RF-ICP (Radio Frequency Inductively Coupled Plasma) negative ion sources. We are developing and parallelizing a two-dimensional three velocity electromagnetic Particle-In-Cell code. The result shows rapid increase in the electron density during the density ramp-up phase. A radial electric field due to the space charge is produced with increase in the electron density and the electron transport in the radial direction is suppressed. As a result, electrons stay for a long period in the region where the inductive electric field is strong, and this leads efficient electron acceleration and a rapid increasing of the electron density.

  18. What is a large-scale dynamo?

    NASA Astrophysics Data System (ADS)

    Nigro, G.; Pongkitiwanichakul, P.; Cattaneo, F.; Tobias, S. M.

    2017-01-01

    We consider kinematic dynamo action in a sheared helical flow at moderate to high values of the magnetic Reynolds number (Rm). We find exponentially growing solutions which, for large enough shear, take the form of a coherent part embedded in incoherent fluctuations. We argue that at large Rm large-scale dynamo action should be identified by the presence of structures coherent in time, rather than those at large spatial scales. We further argue that although the growth rate is determined by small-scale processes, the period of the coherent structures is set by mean-field considerations.

  19. The Large-Scale Plasmaspheric Density Trough Associated With the 24 May 2000 Geomagnetic Storm: IMAGE EUV Observations and Global Core Plasma Modeling

    NASA Technical Reports Server (NTRS)

    Adrian, M. L.; Gallagher, D. L.; Green, J. L.; Sandel, B. R.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    The IMAGE EUV imager observed a plasmaspheric density, trough in association with a geomagnetically active period on 24 May 2000. In EUV, this density, trough appears as an Archimedes spiral extending from Earth's shadow to approximately 1900 MLT. We present an analysis of this density trough using simulated EUV images, Observational EUV images are subjected to edge analysis to establish the plasmapause L-shell and the location of the density trough in terms of L-shell, MLT extent, and radial width. The plasmaspheric density distribution is modeled using both static and dynamic models for the plasmasphere. The background plasmasphere is then numerically simulated using the 4-parameter plasmaspheric density model contained within the Global Core Plasma Model (GCPM) and the Dynamic Global Core Plasma Model (DGCPM). Simulated EUV images of the model plasmasphere are produced once an artificial density, depletion, matching the observed MLT extent and width, has been removed. Once the azimuthal extent and width of the trough have been simulated, the depth of the artificial density depletion is iteratively adjusted to produce simulated EUV images that approximate observation. The results of this analysis and discussion of possible origins for this density trough will be presented.

  20. Totem pole drive decks for the high-voltage, pulsed-power modulator for a large-scale plasma source ion implantation system

    SciTech Connect

    Gribble, R.J.; Reass, W.A.

    1993-07-01

    Plasma source ion implantation (PSII) is an industrially-relevant technique to change the surface composition of materials, thereby improving the mechanical, chemical, electrical, or optical properties. Pre-manufactured parts are immersed in a plasma and are pulsed with a high voltage source that accelerates the ions to the surface, where they become implanted, modifying the surface characteristics. The high voltage applied to the ``workpiece`` is supplied by a high-voltage, pulsed-power modulator capable of operating to 120 kV, with an output pulse width to 20 uS at a repetition rate of up to 2 kHz. Output currents of up to 60 A, and average powers of 225 kW (6.6 MW peak) will be the ultimate capability. Initial system start-up will be limited by a 60 kV, 1 A charging power supply. This paper describes the totem pole drive decks, the ``on`` deck and ``off`` deck, used as a pre-driver to the main high voltage switch tubes which applies power to the workpiece. The pulse length and frequency are externally controlled and then fiber-optically coupled to the modulator totem pole drive decks. The circuitry of the planar triode drivers will be presented in addition to experimental results.

  1. Scaling of the beam-plasma discharge

    NASA Technical Reports Server (NTRS)

    Rowland, H. L.; Papadopoulos, K.; Chang, C. L.

    1981-01-01

    A theoretical analysis is presented of the scaling of the critical beam current required for ignition and the narrow band emissions observed for beam currents less than critical in a beam plasma discharge experiment. The theory of the two-stream interaction between a nonrelativistic cold electron beam and a plasma in the presence of a magnetic field is developed, and conditions for the two-stream instability and the resulting amplification are derived. It is shown that the experimentally observed scaling is consistent with the assumption that the ignition triggering occurs when an instability near the electron plasma frequency is excited. Finally, it is shown that the wave emissions observed in the subthreshold range can be explained by the excitation of the kinetic instability of the upper branch and convective saturation.

  2. Development of atmospheric pressure large area plasma jet for sterilisation and investigation of molecule and plasma interaction

    NASA Astrophysics Data System (ADS)

    Zerbe, Kristina; Iberler, Marcus; Jacoby, Joachim; Wagner, Christopher

    2016-09-01

    The intention of the project is the development and improvement of an atmospheric plasma jet based on various discharge forms (e.g. DBD, RF, micro-array) for sterilisation of biomedical equipment and investigation of biomolecules under the influence of plasma stress. The major objective is to design a plasma jet with a large area and an extended length. Due to the success on small scale plasma sterilisation the request of large area plasma has increased. Many applications of chemical disinfection in environmental and medical cleaning could thereby be complemented. Subsequently, the interaction between plasma and biomolecules should be investigated to improve plasma strerilisation. Special interest will be on non equilibrium plasma electrons affecting the chemical bindings of organic molecules.

  3. Scaling laws in magnetized plasma turbulence

    SciTech Connect

    Boldyrev, Stanislav

    2015-06-28

    Interactions of plasma motion with magnetic fields occur in nature and in the laboratory in an impressively broad range of scales, from megaparsecs in astrophysical systems to centimeters in fusion devices. The fact that such an enormous array of phenomena can be effectively studied lies in the existence of fundamental scaling laws in plasma turbulence, which allow one to scale the results of analytic and numerical modeling to the sized of galaxies, velocities of supernovae explosions, or magnetic fields in fusion devices. Magnetohydrodynamics (MHD) provides the simplest framework for describing magnetic plasma turbulence. Recently, a number of new features of MHD turbulence have been discovered and an impressive array of thought-provoking phenomenological theories have been put forward. However, these theories have conflicting predictions, and the currently available numerical simulations are not able to resolve the contradictions. MHD turbulence exhibits a variety of regimes unusual in regular hydrodynamic turbulence. Depending on the strength of the guide magnetic field it can be dominated by weakly interacting Alfv\\'en waves or strongly interacting wave packets. At small scales such turbulence is locally anisotropic and imbalanced (cross-helical). In a stark contrast with hydrodynamic turbulence, which tends to ``forget'' global constrains and become uniform and isotropic at small scales, MHD turbulence becomes progressively more anisotropic and unbalanced at small scales. Magnetic field plays a fundamental role in turbulent dynamics. Even when such a field is not imposed by external sources, it is self-consistently generated by the magnetic dynamo action. This project aims at a comprehensive study of universal regimes of magnetic plasma turbulence, combining the modern analytic approaches with the state of the art numerical simulations. The proposed study focuses on the three topics: weak MHD turbulence, which is relevant for laboratory devices, the solar

  4. Survey on large scale system control methods

    NASA Technical Reports Server (NTRS)

    Mercadal, Mathieu

    1987-01-01

    The problem inherent to large scale systems such as power network, communication network and economic or ecological systems were studied. The increase in size and flexibility of future spacecraft has put those dynamical systems into the category of large scale systems, and tools specific to the class of large systems are being sought to design control systems that can guarantee more stability and better performance. Among several survey papers, reference was found to a thorough investigation on decentralized control methods. Especially helpful was the classification made of the different existing approaches to deal with large scale systems. A very similar classification is used, even though the papers surveyed are somehow different from the ones reviewed in other papers. Special attention is brought to the applicability of the existing methods to controlling large mechanical systems like large space structures. Some recent developments are added to this survey.

  5. Large-scale instabilities of helical flows

    NASA Astrophysics Data System (ADS)

    Cameron, Alexandre; Alexakis, Alexandros; Brachet, Marc-Étienne

    2016-10-01

    Large-scale hydrodynamic instabilities of periodic helical flows of a given wave number K are investigated using three-dimensional Floquet numerical computations. In the Floquet formalism the unstable field is expanded in modes of different spacial periodicity. This allows us (i) to clearly distinguish large from small scale instabilities and (ii) to study modes of wave number q of arbitrarily large-scale separation q ≪K . Different flows are examined including flows that exhibit small-scale turbulence. The growth rate σ of the most unstable mode is measured as a function of the scale separation q /K ≪1 and the Reynolds number Re. It is shown that the growth rate follows the scaling σ ∝q if an AKA effect [Frisch et al., Physica D: Nonlinear Phenomena 28, 382 (1987), 10.1016/0167-2789(87)90026-1] is present or a negative eddy viscosity scaling σ ∝q2 in its absence. This holds both for the Re≪1 regime where previously derived asymptotic results are verified but also for Re=O (1 ) that is beyond their range of validity. Furthermore, for values of Re above a critical value ReSc beyond which small-scale instabilities are present, the growth rate becomes independent of q and the energy of the perturbation at large scales decreases with scale separation. The nonlinear behavior of these large-scale instabilities is also examined in the nonlinear regime where the largest scales of the system are found to be the most dominant energetically. These results are interpreted by low-order models.

  6. Large-scale dynamics of magnetic helicity

    NASA Astrophysics Data System (ADS)

    Linkmann, Moritz; Dallas, Vassilios

    2016-11-01

    In this paper we investigate the dynamics of magnetic helicity in magnetohydrodynamic (MHD) turbulent flows focusing at scales larger than the forcing scale. Our results show a nonlocal inverse cascade of magnetic helicity, which occurs directly from the forcing scale into the largest scales of the magnetic field. We also observe that no magnetic helicity and no energy is transferred to an intermediate range of scales sufficiently smaller than the container size and larger than the forcing scale. Thus, the statistical properties of this range of scales, which increases with scale separation, is shown to be described to a large extent by the zero flux solutions of the absolute statistical equilibrium theory exhibited by the truncated ideal MHD equations.

  7. Large-scale regions of antimatter

    SciTech Connect

    Grobov, A. V. Rubin, S. G.

    2015-07-15

    Amodified mechanism of the formation of large-scale antimatter regions is proposed. Antimatter appears owing to fluctuations of a complex scalar field that carries a baryon charge in the inflation era.

  8. High-Sensitivity C-Reactive Protein Complements Plasma Epstein-Barr Virus Deoxyribonucleic Acid Prognostication in Nasopharyngeal Carcinoma: A Large-Scale Retrospective and Prospective Cohort Study

    SciTech Connect

    Tang, Lin-Quan; Li, Chao-Feng; Chen, Qiu-Yan; Zhang, Lu; Lai, Xiao-Ping; He, Yun; Xu, Yun-Xiu-Xiu; Hu, Dong-Peng; Wen, Shi-Hua; Peng, Yu-Tuan; Chen, Wen-Hui; Liu, Huai; Guo, Shan-Shan; Liu, Li-Ting; Li, Jing; Zhang, Jing-Ping; and others

    2015-02-01

    Purpose: To evaluate the effects of combining the assessment of circulating high-sensitivity C-reactive protein (hs-CRP) with that of Epstein-Barr virus DNA (EBV DNA) in the pretherapy prognostication of nasopharyngeal carcinoma (NPC). Patients and Methods: Three independent cohorts of NPC patients (training set of n=3113, internal validation set of n=1556, and prospective validation set of n=1668) were studied. Determinants of disease-free survival, distant metastasis–free survival, and overall survival were assessed by multivariate analysis. Hazard ratios and survival probabilities of the patient groups, segregated by clinical stage (T1-2N0-1M0, T3-4N0-1M0, T1-2N2-3M0, and T3-4N2-3M0) and EBV DNA load (low or high) alone, and also according to hs-CRP level (low or high), were compared. Results: Elevated hs-CRP and EBV DNA levels were significantly correlated with poor disease-free survival, distant metastasis–free survival, and overall survival in both the training and validation sets. Associations were similar and remained significant after excluding patients with cardiovascular disease, diabetes, and chronic hepatitis B. Patients with advanced-stage disease were segregated by high EBV DNA levels and high hs-CRP level into a poorest-risk group, and participants with either high EBV DNA but low hs-CRP level or high hs-CRP but low EBV DNA values had poorer survival compared with the bottom values for both biomarkers. These findings demonstrate a significant improvement in the prognostic ability of conventional advanced NPC staging. Conclusion: Baseline plasma EBV DNA and serum hs-CRP levels were significantly correlated with survival in NPC patients. The combined interpretation of EBV DNA with hs-CRP levels led to refinement of the risks for the patient subsets, with improved risk discrimination in patients with advanced-stage disease.

  9. Parametric instabilities in large nonuniform laser plasmas

    SciTech Connect

    Baldis, H.A.; Montgomery, D.S.; Moody, J.D.; Estabrook, K.G.; Berger, R.L.; Kruer, W.L.; Labaune, C.; Batha, S.H.

    1992-09-01

    The study of parametric instabilities in laser plasmas is of vital importance for inertial confinement fusion (ICF). The long scale-length plasma encountered in the corona of an ICF target provides ideal conditions for the growth of instabilities such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and filamentation. These instabilities can have detrimental effects in ICF and their characterization and understanding is of importance. Scattering instabilities are driven through a feedback loop by which the beating between the electromagnetic EM fields of the laser and the scattered light matches the frequency of a local longitudinal mode of the plasma. Any process which interferes with the coherence of this mechanism can substantially alter the behavior of the instability. Of particular interest is the study of laser beam smoothing techniques on parametric instabilities. These techniques are used to improve irradiation uniformity which can suppress hydrodynamic instabilities. Laser beam smoothing techniques have the potential to control the scattering level from parametric instabilities since they provide not only a smoother laser intensity distribution, but also reduced coherence. Beam smoothing techniques that affect the growth of parametric instabilities include spatial smoothing and temporal smoothing by laser bandwidth. Spatial smoothing modifies the phase fronts and temporal distribution of intensities in the focal volume. The transverse intensity spectrum is shifted towards higher spatial wavenumber and can significantly limit the growth of filamentation. Temporal smoothing reduces the coherence time and consequently limits the growth time. Laser bandwidth is required for most smoothing techniques, and can have an independent effect on the instabilities as well.

  10. Studies on plasma production in a large volume system using multiple compact ECR plasma sources

    NASA Astrophysics Data System (ADS)

    Tarey, R. D.; Ganguli, A.; Sahu, D.; Narayanan, R.; Arora, N.

    2017-01-01

    This paper presents a scheme for large volume plasma production using multiple highly portable compact ECR plasma sources (CEPS) (Ganguli et al 2016 Plasma Source Sci. Technol. 25 025026). The large volume plasma system (LVPS) described in the paper is a scalable, cylindrical vessel of diameter  ≈1 m, consisting of source and spacer sections with multiple CEPS mounted symmetrically on the periphery of the source sections. Scaling is achieved by altering the number of source sections/the number of sources in a source section or changing the number of spacer sections for adjusting the spacing between the source sections. A series of plasma characterization experiments using argon gas were conducted on the LVPS under different configurations of CEPS, source and spacer sections, for an operating pressure in the range 0.5-20 mTorr, and a microwave power level in the range 400-500 W per source. Using Langmuir probes (LP), it was possible to show that the plasma density (~1  -  2  ×  1011 cm-3) remains fairly uniform inside the system and decreases marginally close to the chamber wall, and this uniformity increases with an increase in the number of sources. It was seen that a warm electron population (60-80 eV) is always present and is about 0.1% of the bulk plasma density. The mechanism of plasma production is discussed in light of the results obtained for a single CEPS (Ganguli et al 2016 Plasma Source Sci. Technol. 25 025026).

  11. Evaluating Large-Scale Interactive Radio Programmes

    ERIC Educational Resources Information Center

    Potter, Charles; Naidoo, Gordon

    2009-01-01

    This article focuses on the challenges involved in conducting evaluations of interactive radio programmes in South Africa with large numbers of schools, teachers, and learners. It focuses on the role such large-scale evaluation has played during the South African radio learning programme's development stage, as well as during its subsequent…

  12. Multi-Scale Modeling of Plasma Thrusters

    NASA Astrophysics Data System (ADS)

    Batishchev, Oleg

    2004-11-01

    Plasma thrusters are characterized with multiple spatial and temporal scales, which are due to the intrinsic physical processes such as gas ionization, wall effects and plasma acceleration. Characteristic times for hot plasma and cold gas are differing by 6-7 orders of magnitude. The typical collisional mean-free-paths vary by 3-5 orders along the devices. These make questionable a true self-consistent modeling of the thrusters. The latter is vital to the understanding of complex physics, non-linear dynamics and optimization of the performance. To overcome this problem we propose the following approach. All processes are divided into two groups: fast and slow. The slow ones include gas evolution with known sources and ionization sink. The ionization rate, transport coefficients, energy sources are defined during "fast step". Both processes are linked through external iterations. Multiple spatial scales are handled using moving adaptive mesh. Development and application of this method to the VASIMR helicon plasma source and other thrusters will be discussed. Supported by NASA.

  13. Large-scale cortical networks and cognition.

    PubMed

    Bressler, S L

    1995-03-01

    The well-known parcellation of the mammalian cerebral cortex into a large number of functionally distinct cytoarchitectonic areas presents a problem for understanding the complex cortical integrative functions that underlie cognition. How do cortical areas having unique individual functional properties cooperate to accomplish these complex operations? Do neurons distributed throughout the cerebral cortex act together in large-scale functional assemblages? This review examines the substantial body of evidence supporting the view that complex integrative functions are carried out by large-scale networks of cortical areas. Pathway tracing studies in non-human primates have revealed widely distributed networks of interconnected cortical areas, providing an anatomical substrate for large-scale parallel processing of information in the cerebral cortex. Functional coactivation of multiple cortical areas has been demonstrated by neurophysiological studies in non-human primates and several different cognitive functions have been shown to depend on multiple distributed areas by human neuropsychological studies. Electrophysiological studies on interareal synchronization have provided evidence that active neurons in different cortical areas may become not only coactive, but also functionally interdependent. The computational advantages of synchronization between cortical areas in large-scale networks have been elucidated by studies using artificial neural network models. Recent observations of time-varying multi-areal cortical synchronization suggest that the functional topology of a large-scale cortical network is dynamically reorganized during visuomotor behavior.

  14. Progress in Long Scale Length Laser-Plasma Interactions

    SciTech Connect

    Glenzer, S H; Arnold, P; Bardsley, G; Berger, R L; Bonanno, G; Borger, T; Bower, D E; Bowers, M; Bryant, R; Buckman, S; Burkhart, S C; Campbell, K; Chrisp, M P; Cohen, B I; Constantin, G; Cooper, F; Cox, J; Dewald, E; Divol, L; Dixit, S; Duncan, J; Eder, D; Edwards, J; Erbert, G; Felker, B; Fornes, J; Frieders, G; Froula, D H; Gardner, S D; Gates, C; Gonzalez, M; Grace, S; Gregori, G; Greenwood, A; Griffith, R; Hall, T; Hammel, B A; Haynam, C; Heestand, G; Henesian, M; Hermes, G; Hinkel, D; Holder, J; Holdner, F; Holtmeier, G; Hsing, W; Huber, S; James, T; Johnson, S; Jones, O S; Kalantar, D; Kamperschroer, J H; Kauffman, R; Kelleher, T; Knight, J; Kirkwood, R K; Kruer, W L; Labiak, W; Landen, O L; Langdon, A B; Langer, S; Latray, D; Lee, A; Lee, F D; Lund, D; MacGowan, B; Marshall, S; McBride, J; McCarville, T; McGrew, L; Mackinnon, A J; Mahavandi, S; Manes, K; Marshall, C; Mertens, E; Meezan, N; Miller, G; Montelongo, S; Moody, J D; Moses, E; Munro, D; Murray, J; Neumann, J; Newton, M; Ng, E; Niemann, C; Nikitin, A; Opsahl, P; Padilla, E; Parham, T; Parrish, G; Petty, C; Polk, M; Powell, C; Reinbachs, I; Rekow, V; Rinnert, R; Riordan, B; Rhodes, M

    2003-11-11

    The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneously heated plasmas with densities of n{sub e} = 6 x 10{sup 20} cm{sup -3} and temperatures of T{sub e} = 2 keV. The high energy in a NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last {approx}1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 6% for the smallest length ({approx}2 mm). increasing to 12% for {approx}7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modeling of the laser-plasma interactions at ignition-size scale lengths.

  15. Large-scale nanophotonic phased array.

    PubMed

    Sun, Jie; Timurdogan, Erman; Yaacobi, Ami; Hosseini, Ehsan Shah; Watts, Michael R

    2013-01-10

    Electromagnetic phased arrays at radio frequencies are well known and have enabled applications ranging from communications to radar, broadcasting and astronomy. The ability to generate arbitrary radiation patterns with large-scale phased arrays has long been pursued. Although it is extremely expensive and cumbersome to deploy large-scale radiofrequency phased arrays, optical phased arrays have a unique advantage in that the much shorter optical wavelength holds promise for large-scale integration. However, the short optical wavelength also imposes stringent requirements on fabrication. As a consequence, although optical phased arrays have been studied with various platforms and recently with chip-scale nanophotonics, all of the demonstrations so far are restricted to one-dimensional or small-scale two-dimensional arrays. Here we report the demonstration of a large-scale two-dimensional nanophotonic phased array (NPA), in which 64 × 64 (4,096) optical nanoantennas are densely integrated on a silicon chip within a footprint of 576 μm × 576 μm with all of the nanoantennas precisely balanced in power and aligned in phase to generate a designed, sophisticated radiation pattern in the far field. We also show that active phase tunability can be realized in the proposed NPA by demonstrating dynamic beam steering and shaping with an 8 × 8 array. This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide-semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips. In turn, this enables arbitrary radiation pattern generation using NPAs and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large-scale deployment in applications such as communication, laser detection and ranging, three-dimensional holography and biomedical sciences, to name just a few.

  16. Large-scale Alfvén vortices

    SciTech Connect

    Onishchenko, O. G.; Horton, W.; Scullion, E.; Fedun, V.

    2015-12-15

    The new type of large-scale vortex structures of dispersionless Alfvén waves in collisionless plasma is investigated. It is shown that Alfvén waves can propagate in the form of Alfvén vortices of finite characteristic radius and characterised by magnetic flux ropes carrying orbital angular momentum. The structure of the toroidal and radial velocity, fluid and magnetic field vorticity, the longitudinal electric current in the plane orthogonal to the external magnetic field are discussed.

  17. "Cosmological Parameters from Large Scale Structure"

    NASA Technical Reports Server (NTRS)

    Hamilton, A. J. S.

    2005-01-01

    This grant has provided primary support for graduate student Mark Neyrinck, and some support for the PI and for colleague Nick Gnedin, who helped co-supervise Neyrinck. This award had two major goals. First, to continue to develop and apply methods for measuring galaxy power spectra on large, linear scales, with a view to constraining cosmological parameters. And second, to begin try to understand galaxy clustering at smaller. nonlinear scales well enough to constrain cosmology from those scales also. Under this grant, the PI and collaborators, notably Max Tegmark. continued to improve their technology for measuring power spectra from galaxy surveys at large, linear scales. and to apply the technology to surveys as the data become available. We believe that our methods are best in the world. These measurements become the foundation from which we and other groups measure cosmological parameters.

  18. Scaling laws for particle growth in plasma reactors

    SciTech Connect

    Lemons, D.S.; Keinigs, R.K.; Winske, D.; Jones, M.E.

    1996-01-01

    We quantify a model which incorporates observed features of contaminant particle growth in plasma processing reactors. According to the model, large {open_quote}{open_quote}predator{close_quote}{close_quote} particles grow by adsorbing smaller, typically neutral, {open_quote}{open_quote}prey{close_quote}{close_quote} protoparticles. The latter are supplied by an assumed constant mass injection of contaminant material. Scaling laws and quantitative predictions compare favorably with published experimental results. {copyright} {ital 1996 American Institute of Physics.}

  19. Magnetic Helicity and Large Scale Magnetic Fields: A Primer

    NASA Astrophysics Data System (ADS)

    Blackman, Eric G.

    2015-05-01

    Magnetic fields of laboratory, planetary, stellar, and galactic plasmas commonly exhibit significant order on large temporal or spatial scales compared to the otherwise random motions within the hosting system. Such ordered fields can be measured in the case of planets, stars, and galaxies, or inferred indirectly by the action of their dynamical influence, such as jets. Whether large scale fields are amplified in situ or a remnant from previous stages of an object's history is often debated for objects without a definitive magnetic activity cycle. Magnetic helicity, a measure of twist and linkage of magnetic field lines, is a unifying tool for understanding large scale field evolution for both mechanisms of origin. Its importance stems from its two basic properties: (1) magnetic helicity is typically better conserved than magnetic energy; and (2) the magnetic energy associated with a fixed amount of magnetic helicity is minimized when the system relaxes this helical structure to the largest scale available. Here I discuss how magnetic helicity has come to help us understand the saturation of and sustenance of large scale dynamos, the need for either local or global helicity fluxes to avoid dynamo quenching, and the associated observational consequences. I also discuss how magnetic helicity acts as a hindrance to turbulent diffusion of large scale fields, and thus a helper for fossil remnant large scale field origin models in some contexts. I briefly discuss the connection between large scale fields and accretion disk theory as well. The goal here is to provide a conceptual primer to help the reader efficiently penetrate the literature.

  20. Nusselt number scaling in tokamak plasma turbulence

    SciTech Connect

    Takeda, K.; Benkadda, S.; Hamaguchi, S.; Wakatani, M.

    2005-05-15

    Anomalous heat transport caused by ion temperature gradient (ITG) driven turbulence in tokamak plasmas is evaluated from numerical simulations of the two-dimensional (2D) partial-differential equations of the ITG model and of a reduced 1D version derived from a quasilinear approximation. In the strongly turbulent state, intermittent bursts of thermal transport are observed in both cases. In the strongly turbulent regime, the reduced model as well as the direct numerical simulation show that the Nusselt number Nu (normalized heat flux) scales with the normalized ion pressure gradient K{sub i} as Nu{proportional_to}K{sub i}{sup 1/3}. Since the Rayleigh number for ITG turbulence is proportional to K{sub i}, the Nusselt number scaling for ITG turbulence is thus similar to the classical thermal transport scaling for Rayleigh-Benard convections in neutral fluids.

  1. The large-scale distribution of galaxies

    NASA Technical Reports Server (NTRS)

    Geller, Margaret J.

    1989-01-01

    The spatial distribution of galaxies in the universe is characterized on the basis of the six completed strips of the Harvard-Smithsonian Center for Astrophysics redshift-survey extension. The design of the survey is briefly reviewed, and the results are presented graphically. Vast low-density voids similar to the void in Bootes are found, almost completely surrounded by thin sheets of galaxies. Also discussed are the implications of the results for the survey sampling problem, the two-point correlation function of the galaxy distribution, the possibility of detecting large-scale coherent flows, theoretical models of large-scale structure, and the identification of groups and clusters of galaxies.

  2. Fast figuring of large optics by reactive atom plasma

    NASA Astrophysics Data System (ADS)

    Castelli, Marco; Jourdain, Renaud; Morantz, Paul; Shore, Paul

    2012-09-01

    The next generation of ground-based astronomical observatories will require fabrication and maintenance of extremely large segmented mirrors tens of meters in diameter. At present, the large production of segments required by projects like E-ELT and TMT poses time frames and costs feasibility questions. This is principally due to a bottleneck stage in the optical fabrication chain: the final figuring step. State-of-the-art figure correction techniques, so far, have failed to meet the needs of the astronomical community for mass production of large, ultra-precise optical surfaces. In this context, Reactive Atom Plasma (RAP) is proposed as a candidate figuring process that combines nanometer level accuracy with high material removal rates. RAP is a form of plasma enhanced chemical etching at atmospheric pressure based on Inductively Coupled Plasma technology. The rapid figuring capability of the RAP process has already been proven on medium sized optical surfaces made of silicon based materials. In this paper, the figure correction of a 3 meters radius of curvature, 400 mm diameter spherical ULE mirror is presented. This work demonstrates the large scale figuring capability of the Reactive Atom Plasma process. The figuring is carried out by applying an in-house developed procedure that promotes rapid convergence. A 2.3 μm p-v initial figure error is removed within three iterations, for a total processing time of 2.5 hours. The same surface is then re-polished and the residual error corrected again down to λ/20 nm rms. These results highlight the possibility of figuring a metre-class mirror in about ten hours.

  3. Laser-plasma interactions in large gas-filled hohlraums

    SciTech Connect

    Turner, R.E.; Powers, L.V.; Berger, R.L.

    1996-06-01

    Indirect-drive targets planned for the National Ignition Facility (NIF) laser consist of spherical fuel capsules enclosed in cylindrical Au hohlraums. Laser beams, arranged in cylindrical rings, heat the inside of the Au wall to produce x rays that in turn heat and implode the capsule to produce fusion conditions in the fuel. Detailed calculations show that adequate implosion symmetry can be maintained by filling the hohlraum interior with low-density, low-Z gases. The plasma produced from the heated gas provides sufficient pressure to keep the radiating Au surface from expanding excessively. As the laser heats this gas, the gas becomes a relatively uniform plasma with small gradients in velocity and density. Such long-scale-length plasmas can be ideal mediums for stimulated Brillouin Scattering (SBS). SBS can reflect a large fraction of the incident laser light before it is absorbed by the hohlraum; therefore, it is undesirable in an inertial confinement fusion target. To examine the importance of SBS in NIF targets, the authors used Nova to measure SBS from hohlraums with plasma conditions similar to those predicted for high-gain NIF targets. The plasmas differ from the more familiar exploding foil or solid targets as follows: they are hot (3 keV); they have high electron densities (n{sub e}=10{sup 21}cm{sup {minus}3}); and they are nearly stationary, confined within an Au cylinder, and uniform over large distances (>2 mm). These hohlraums have <3% peak SBS backscatter for an interaction beam with intensities of 1-4 x 10{sup 15} W/cm{sup 2}, a laser wavelength of 0.351{micro}m, f/4 or f/8 focusing optics, and a variety of beam smoothing implementations. Based on these conditions the authors conclude that SBS does not appear to be a problem for NIF targets.

  4. Large-scale neuromorphic computing systems

    NASA Astrophysics Data System (ADS)

    Furber, Steve

    2016-10-01

    Neuromorphic computing covers a diverse range of approaches to information processing all of which demonstrate some degree of neurobiological inspiration that differentiates them from mainstream conventional computing systems. The philosophy behind neuromorphic computing has its origins in the seminal work carried out by Carver Mead at Caltech in the late 1980s. This early work influenced others to carry developments forward, and advances in VLSI technology supported steady growth in the scale and capability of neuromorphic devices. Recently, a number of large-scale neuromorphic projects have emerged, taking the approach to unprecedented scales and capabilities. These large-scale projects are associated with major new funding initiatives for brain-related research, creating a sense that the time and circumstances are right for progress in our understanding of information processing in the brain. In this review we present a brief history of neuromorphic engineering then focus on some of the principal current large-scale projects, their main features, how their approaches are complementary and distinct, their advantages and drawbacks, and highlight the sorts of capabilities that each can deliver to neural modellers.

  5. Management of large-scale technology

    NASA Technical Reports Server (NTRS)

    Levine, A.

    1985-01-01

    Two major themes are addressed in this assessment of the management of large-scale NASA programs: (1) how a high technology agency was a decade marked by a rapid expansion of funds and manpower in the first half and almost as rapid contraction in the second; and (2) how NASA combined central planning and control with decentralized project execution.

  6. Large-scale Advanced Propfan (LAP) program

    NASA Technical Reports Server (NTRS)

    Sagerser, D. A.; Ludemann, S. G.

    1985-01-01

    The propfan is an advanced propeller concept which maintains the high efficiencies traditionally associated with conventional propellers at the higher aircraft cruise speeds associated with jet transports. The large-scale advanced propfan (LAP) program extends the research done on 2 ft diameter propfan models to a 9 ft diameter article. The program includes design, fabrication, and testing of both an eight bladed, 9 ft diameter propfan, designated SR-7L, and a 2 ft diameter aeroelastically scaled model, SR-7A. The LAP program is complemented by the propfan test assessment (PTA) program, which takes the large-scale propfan and mates it with a gas generator and gearbox to form a propfan propulsion system and then flight tests this system on the wing of a Gulfstream 2 testbed aircraft.

  7. Experimental Simulations of Large-Scale Collisions

    NASA Technical Reports Server (NTRS)

    Housen, Kevin R.

    2002-01-01

    This report summarizes research on the effects of target porosity on the mechanics of impact cratering. Impact experiments conducted on a centrifuge provide direct simulations of large-scale cratering on porous asteroids. The experiments show that large craters in porous materials form mostly by compaction, with essentially no deposition of material into the ejecta blanket that is a signature of cratering in less-porous materials. The ratio of ejecta mass to crater mass is shown to decrease with increasing crater size or target porosity. These results are consistent with the observation that large closely-packed craters on asteroid Mathilde appear to have formed without degradation to earlier craters.

  8. Ferroelectric opening switches for large-scale pulsed power drivers.

    SciTech Connect

    Brennecka, Geoffrey L.; Rudys, Joseph Matthew; Reed, Kim Warren; Pena, Gary Edward; Tuttle, Bruce Andrew; Glover, Steven Frank

    2009-11-01

    Fast electrical energy storage or Voltage-Driven Technology (VDT) has dominated fast, high-voltage pulsed power systems for the past six decades. Fast magnetic energy storage or Current-Driven Technology (CDT) is characterized by 10,000 X higher energy density than VDT and has a great number of other substantial advantages, but it has all but been neglected for all of these decades. The uniform explanation for neglect of CDT technology is invariably that the industry has never been able to make an effective opening switch, which is essential for the use of CDT. Most approaches to opening switches have involved plasma of one sort or another. On a large scale, gaseous plasmas have been used as a conductor to bridge the switch electrodes that provides an opening function when the current wave front propagates through to the output end of the plasma and fully magnetizes the plasma - this is called a Plasma Opening Switch (POS). Opening can be triggered in a POS using a magnetic field to push the plasma out of the A-K gap - this is called a Magnetically Controlled Plasma Opening Switch (MCPOS). On a small scale, depletion of electron plasmas in semiconductor devices is used to affect opening switch behavior, but these devices are relatively low voltage and low current compared to the hundreds of kilo-volts and tens of kilo-amperes of interest to pulsed power. This work is an investigation into an entirely new approach to opening switch technology that utilizes new materials in new ways. The new materials are Ferroelectrics and using them as an opening switch is a stark contrast to their traditional applications in optics and transducer applications. Emphasis is on use of high performance ferroelectrics with the objective of developing an opening switch that would be suitable for large scale pulsed power applications. Over the course of exploring this new ground, we have discovered new behaviors and properties of these materials that were here to fore unknown. Some of

  9. Neutrino footprint in large scale structure

    NASA Astrophysics Data System (ADS)

    Garay, Carlos Peña; Verde, Licia; Jimenez, Raul

    2017-03-01

    Recent constrains on the sum of neutrino masses inferred by analyzing cosmological data, show that detecting a non-zero neutrino mass is within reach of forthcoming cosmological surveys. Such a measurement will imply a direct determination of the absolute neutrino mass scale. Physically, the measurement relies on constraining the shape of the matter power spectrum below the neutrino free streaming scale: massive neutrinos erase power at these scales. However, detection of a lack of small-scale power from cosmological data could also be due to a host of other effects. It is therefore of paramount importance to validate neutrinos as the source of power suppression at small scales. We show that, independent on hierarchy, neutrinos always show a footprint on large, linear scales; the exact location and properties are fully specified by the measured power suppression (an astrophysical measurement) and atmospheric neutrinos mass splitting (a neutrino oscillation experiment measurement). This feature cannot be easily mimicked by systematic uncertainties in the cosmological data analysis or modifications in the cosmological model. Therefore the measurement of such a feature, up to 1% relative change in the power spectrum for extreme differences in the mass eigenstates mass ratios, is a smoking gun for confirming the determination of the absolute neutrino mass scale from cosmological observations. It also demonstrates the synergy between astrophysics and particle physics experiments.

  10. Scale up of large ALON windows

    NASA Astrophysics Data System (ADS)

    Goldman, Lee M.; Balasubramanian, Sreeram; Kashalikar, Uday; Foti, Robyn; Sastri, Suri

    2013-06-01

    Aluminum Oxynitride (ALON® Optical Ceramic) combines broadband transparency with excellent mechanical properties. ALON's cubic structure means that it is transparent in its polycrystalline form, allowing it to be manufactured by conventional powder processing techniques. Surmet has established a robust manufacturing process, beginning with synthesis of ALON® powder, continuing through forming/heat treatment of blanks, and ending with optical fabrication of ALON® windows. Surmet has made significant progress in our production capability in recent years. Additional scale up of Surmet's manufacturing capability, for larger sizes and higher quantities, is currently underway. ALON® transparent armor represents the state of the art in protection against armor piercing threats, offering a factor of two in weight and thickness savings over conventional glass laminates. Tiled and monolithic windows have been successfully produced and tested against a range of threats. Large ALON® window are also of interest to a range of visible to Mid-Wave Infra-Red (MWIR) sensor applications. These applications often have stressing imaging requirements which in turn require that these large windows have optical characteristics including excellent homogeneity of index of refraction and very low stress birefringence. Surmet is currently scaling up its production facility to be able to make and deliver ALON® monolithic windows as large as ~19x36-in. Additionally, Surmet has plans to scale up to windows ~3ftx3ft in size in the coming years. Recent results with scale up and characterization of the resulting blanks will be presented.

  11. Large-Scale PV Integration Study

    SciTech Connect

    Lu, Shuai; Etingov, Pavel V.; Diao, Ruisheng; Ma, Jian; Samaan, Nader A.; Makarov, Yuri V.; Guo, Xinxin; Hafen, Ryan P.; Jin, Chunlian; Kirkham, Harold; Shlatz, Eugene; Frantzis, Lisa; McClive, Timothy; Karlson, Gregory; Acharya, Dhruv; Ellis, Abraham; Stein, Joshua; Hansen, Clifford; Chadliev, Vladimir; Smart, Michael; Salgo, Richard; Sorensen, Rahn; Allen, Barbara; Idelchik, Boris

    2011-07-29

    This research effort evaluates the impact of large-scale photovoltaic (PV) and distributed generation (DG) output on NV Energy’s electric grid system in southern Nevada. It analyzes the ability of NV Energy’s generation to accommodate increasing amounts of utility-scale PV and DG, and the resulting cost of integrating variable renewable resources. The study was jointly funded by the United States Department of Energy and NV Energy, and conducted by a project team comprised of industry experts and research scientists from Navigant Consulting Inc., Sandia National Laboratories, Pacific Northwest National Laboratory and NV Energy.

  12. Condition Monitoring of Large-Scale Facilities

    NASA Technical Reports Server (NTRS)

    Hall, David L.

    1999-01-01

    This document provides a summary of the research conducted for the NASA Ames Research Center under grant NAG2-1182 (Condition-Based Monitoring of Large-Scale Facilities). The information includes copies of view graphs presented at NASA Ames in the final Workshop (held during December of 1998), as well as a copy of a technical report provided to the COTR (Dr. Anne Patterson-Hine) subsequent to the workshop. The material describes the experimental design, collection of data, and analysis results associated with monitoring the health of large-scale facilities. In addition to this material, a copy of the Pennsylvania State University Applied Research Laboratory data fusion visual programming tool kit was also provided to NASA Ames researchers.

  13. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2008-09-30

    aerosol species up to six days in advance anywhere on the globe. NAAPS and COAMPS are particularly useful for forecasts of dust storms in areas...impact cloud processes globally. With increasing dust storms due to climate change and land use changes in desert regions, the impact of the...bacteria in large-scale dust storms is expected to significantly impact warm ice cloud formation, human health, and ecosystems globally. In Niemi et al

  14. Economically viable large-scale hydrogen liquefaction

    NASA Astrophysics Data System (ADS)

    Cardella, U.; Decker, L.; Klein, H.

    2017-02-01

    The liquid hydrogen demand, particularly driven by clean energy applications, will rise in the near future. As industrial large scale liquefiers will play a major role within the hydrogen supply chain, production capacity will have to increase by a multiple of today’s typical sizes. The main goal is to reduce the total cost of ownership for these plants by increasing energy efficiency with innovative and simple process designs, optimized in capital expenditure. New concepts must ensure a manageable plant complexity and flexible operability. In the phase of process development and selection, a dimensioning of key equipment for large scale liquefiers, such as turbines and compressors as well as heat exchangers, must be performed iteratively to ensure technological feasibility and maturity. Further critical aspects related to hydrogen liquefaction, e.g. fluid properties, ortho-para hydrogen conversion, and coldbox configuration, must be analysed in detail. This paper provides an overview on the approach, challenges and preliminary results in the development of efficient as well as economically viable concepts for large-scale hydrogen liquefaction.

  15. Large-Scale Visual Data Analysis

    NASA Astrophysics Data System (ADS)

    Johnson, Chris

    2014-04-01

    Modern high performance computers have speeds measured in petaflops and handle data set sizes measured in terabytes and petabytes. Although these machines offer enormous potential for solving very large-scale realistic computational problems, their effectiveness will hinge upon the ability of human experts to interact with their simulation results and extract useful information. One of the greatest scientific challenges of the 21st century is to effectively understand and make use of the vast amount of information being produced. Visual data analysis will be among our most most important tools in helping to understand such large-scale information. Our research at the Scientific Computing and Imaging (SCI) Institute at the University of Utah has focused on innovative, scalable techniques for large-scale 3D visual data analysis. In this talk, I will present state- of-the-art visualization techniques, including scalable visualization algorithms and software, cluster-based visualization methods and innovate visualization techniques applied to problems in computational science, engineering, and medicine. I will conclude with an outline for a future high performance visualization research challenges and opportunities.

  16. Large scale preparation of pure phycobiliproteins.

    PubMed

    Padgett, M P; Krogmann, D W

    1987-01-01

    This paper describes simple procedures for the purification of large amounts of phycocyanin and allophycocyanin from the cyanobacterium Microcystis aeruginosa. A homogeneous natural bloom of this organism provided hundreds of kilograms of cells. Large samples of cells were broken by freezing and thawing. Repeated extraction of the broken cells with distilled water released phycocyanin first, then allophycocyanin, and provides supporting evidence for the current models of phycobilisome structure. The very low ionic strength of the aqueous extracts allowed allophycocyanin release in a particulate form so that this protein could be easily concentrated by centrifugation. Other proteins in the extract were enriched and concentrated by large scale membrane filtration. The biliproteins were purified to homogeneity by chromatography on DEAE cellulose. Purity was established by HPLC and by N-terminal amino acid sequence analysis. The proteins were examined for stability at various pHs and exposures to visible light.

  17. Large Scale CW ECRH Systems: Some considerations

    NASA Astrophysics Data System (ADS)

    Erckmann, V.; Kasparek, W.; Plaum, B.; Lechte, C.; Petelin, M. I.; Braune, H.; Gantenbein, G.; Laqua, H. P.; Lubiako, L.; Marushchenko, N. B.; Michel, G.; Turkin, Y.; Weissgerber, M.

    2012-09-01

    Electron Cyclotron Resonance Heating (ECRH) is a key component in the heating arsenal for the next step fusion devices like W7-X and ITER. These devices are equipped with superconducting coils and are designed to operate steady state. ECRH must thus operate in CW-mode with a large flexibility to comply with various physics demands such as plasma start-up, heating and current drive, as well as configurationand MHD - control. The request for many different sophisticated applications results in a growing complexity, which is in conflict with the request for high availability, reliability, and maintainability. `Advanced' ECRH-systems must, therefore, comply with both the complex physics demands and operational robustness and reliability. The W7-X ECRH system is the first CW- facility of an ITER relevant size and is used as a test bed for advanced components. Proposals for future developments are presented together with improvements of gyrotrons, transmission components and launchers.

  18. Supporting large-scale computational science

    SciTech Connect

    Musick, R

    1998-10-01

    A study has been carried out to determine the feasibility of using commercial database management systems (DBMSs) to support large-scale computational science. Conventional wisdom in the past has been that DBMSs are too slow for such data. Several events over the past few years have muddied the clarity of this mindset: 1. 2. 3. 4. Several commercial DBMS systems have demonstrated storage and ad-hoc quer access to Terabyte data sets. Several large-scale science teams, such as EOSDIS [NAS91], high energy physics [MM97] and human genome [Kin93] have adopted (or make frequent use of) commercial DBMS systems as the central part of their data management scheme. Several major DBMS vendors have introduced their first object-relational products (ORDBMSs), which have the potential to support large, array-oriented data. In some cases, performance is a moot issue. This is true in particular if the performance of legacy applications is not reduced while new, albeit slow, capabilities are added to the system. The basic assessment is still that DBMSs do not scale to large computational data. However, many of the reasons have changed, and there is an expiration date attached to that prognosis. This document expands on this conclusion, identifies the advantages and disadvantages of various commercial approaches, and describes the studies carried out in exploring this area. The document is meant to be brief, technical and informative, rather than a motivational pitch. The conclusions within are very likely to become outdated within the next 5-7 years, as market forces will have a significant impact on the state of the art in scientific data management over the next decade.

  19. The Cosmology Large Angular Scale Surveyor

    NASA Astrophysics Data System (ADS)

    Ali, Aamir; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Dahal, Sumit; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Fluxa, Pedro; Halpern, Mark; Hilton, Gene; Hinshaw, Gary F.; Hubmayr, Johannes; Iuliano, Jeffrey; Karakla, John; Marriage, Tobias; McMahon, Jeff; Miller, Nathan; Moseley, Samuel H.; Palma, Gonzalo; Parker, Lucas; Petroff, Matthew; Pradenas, Bastián; Rostem, Karwan; Sagliocca, Marco; Valle, Deniz; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen

    2017-01-01

    The Cosmology Large Angular Scale Surveryor (CLASS) is a ground based telescope array designed to measure the large-angular scale polarization signal of the Cosmic Microwave Background (CMB). The large-angular scale CMB polarization measurement is essential for a precise determination of the optical depth to reionization (from the E-mode polarization) and a characterization of inflation from the predicted polarization pattern imprinted on the CMB by gravitational waves in the early universe (from the B-mode polarization). CLASS will characterize the primordial tensor-to-scalar ratio, r, to 0.01 (95% CL).CLASS is uniquely designed to be sensitive to the primordial B-mode signal across the entire range of angular scales where it could possibly dominate over the lensing signal that converts E-modes to B-modes while also making multi-frequency observations both high and low of the frequency where the CMB-to-foreground signal ratio is at its maximum. The design enables CLASS to make a definitive cosmic-variance-limited measurement of the optical depth to scattering from reionization.CLASS is an array of 4 telescopes operating at approximately 40, 90, 150, and 220 GHz. CLASS is located high in the Andes mountains in the Atacama Desert of northern Chile. The location of the CLASS site at high altitude near the equator minimizes atmospheric emission while allowing for daily mapping of ~70% of the sky.A rapid front end Variable-delay Polarization Modulator (VPM) and low noise Transition Edge Sensor (TES) detectors allow for a high sensitivity and low systematic error mapping of the CMB polarization at large angular scales. The VPM, detectors and their coupling structures were all uniquely designed and built for CLASS.We present here an overview of the CLASS scientific strategy, instrument design, and current progress. Particular attention is given to the development and status of the Q-band receiver currently surveying the sky from the Atacama Desert and the development of

  20. The Cosmology Large Angular Scale Surveyor (CLASS)

    NASA Technical Reports Server (NTRS)

    Harrington, Kathleen; Marriange, Tobias; Aamir, Ali; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Denis, Kevin; Moseley, Samuel H.; Rostem, Karwan; Wollack, Edward

    2016-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).

  1. The Cosmology Large Angular Scale Surveyor

    NASA Astrophysics Data System (ADS)

    Harrington, Kathleen; Marriage, Tobias; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Dahal, Sumit; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Fluxa, Pedro; Halpern, Mark; Hilton, Gene; Hinshaw, Gary F.; Hubmayr, Johannes; Iuliano, Jeffrey; Karakla, John; McMahon, Jeff; Miller, Nathan T.; Moseley, Samuel H.; Palma, Gonzalo; Parker, Lucas; Petroff, Matthew; Pradenas, Bastián.; Rostem, Karwan; Sagliocca, Marco; Valle, Deniz; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen

    2016-07-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).

  2. Suppressed ion-scale turbulence in a hot high-β plasma

    PubMed Central

    Schmitz, L.; Fulton, D. P.; Ruskov, E.; Lau, C.; Deng, B. H.; Tajima, T.; Binderbauer, M. W.; Holod, I.; Lin, Z.; Gota, H.; Tuszewski, M.; Dettrick, S. A.; Steinhauer, L. C.

    2016-01-01

    An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements. PMID:28000675

  3. Suppressed ion-scale turbulence in a hot high-β plasma.

    PubMed

    Schmitz, L; Fulton, D P; Ruskov, E; Lau, C; Deng, B H; Tajima, T; Binderbauer, M W; Holod, I; Lin, Z; Gota, H; Tuszewski, M; Dettrick, S A; Steinhauer, L C

    2016-12-21

    An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements.

  4. Suppressed ion-scale turbulence in a hot high-β plasma

    NASA Astrophysics Data System (ADS)

    Schmitz, L.; Fulton, D. P.; Ruskov, E.; Lau, C.; Deng, B. H.; Tajima, T.; Binderbauer, M. W.; Holod, I.; Lin, Z.; Gota, H.; Tuszewski, M.; Dettrick, S. A.; Steinhauer, L. C.

    2016-12-01

    An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements.

  5. Large-amplitude solitons in gravitationally balanced quantum plasmas

    SciTech Connect

    Akbari-Moghanjoughi, M.

    2014-08-15

    Using the quantum fluid model for self-gravitating quantum plasmas with the Bernoulli pseudopotential method and taking into account the relativistic degeneracy effect, it is shown that gravity-induced large-amplitude density rarefaction solitons can exist in gravitationally balanced quantum plasmas. These nonlinear solitons are generated due to the force imbalance between the gravity and the quantum fluid pressure via local density perturbations, similar to that on shallow waters. It is found that both the fluid mass-density and the atomic-number of the constituent ions have significant effect on the amplitude and width of these solitonic profiles. Existence of a large-scale gravity-induced solitonic activities on neutron-star surface, for instance, can be a possible explanation for the recently proposed resonant shattering mechanism [D. Tsang et al., Phys. Rev. Lett. 108, 011102 (2012)] causing the intense short gamma ray burst phenomenon, in which release of ≃10{sup 46}–10{sup 47} ergs would be possible from the surface. The resonant shattering of the crust in a neutron star has been previously attributed to the crust-core interface mode and the tidal surface tensions. We believe that current model can be a more natural explanation for the energy liberation by solitonic activities on the neutron star surfaces, without a requirement for external mergers like other neutron stars or black holes for the crustal shatter.

  6. Large-scale quasi-geostrophic magnetohydrodynamics

    SciTech Connect

    Balk, Alexander M.

    2014-12-01

    We consider the ideal magnetohydrodynamics (MHD) of a shallow fluid layer on a rapidly rotating planet or star. The presence of a background toroidal magnetic field is assumed, and the 'shallow water' beta-plane approximation is used. We derive a single equation for the slow large length scale dynamics. The range of validity of this equation fits the MHD of the lighter fluid at the top of Earth's outer core. The form of this equation is similar to the quasi-geostrophic (Q-G) equation (for usual ocean or atmosphere), but the parameters are essentially different. Our equation also implies the inverse cascade; but contrary to the usual Q-G situation, the energy cascades to smaller length scales, while the enstrophy cascades to the larger scales. We find the Kolmogorov-type spectrum for the inverse cascade. The spectrum indicates the energy accumulation in larger scales. In addition to the energy and enstrophy, the obtained equation possesses an extra (adiabatic-type) invariant. Its presence implies energy accumulation in the 30° sector around zonal direction. With some special energy input, the extra invariant can lead to the accumulation of energy in zonal magnetic field; this happens if the input of the extra invariant is small, while the energy input is considerable.

  7. Large-scale optimization of neuron arbors

    NASA Astrophysics Data System (ADS)

    Cherniak, Christopher; Changizi, Mark; Won Kang, Du

    1999-05-01

    At the global as well as local scales, some of the geometry of types of neuron arbors-both dendrites and axons-appears to be self-organizing: Their morphogenesis behaves like flowing water, that is, fluid dynamically; waterflow in branching networks in turn acts like a tree composed of cords under tension, that is, vector mechanically. Branch diameters and angles and junction sites conform significantly to this model. The result is that such neuron tree samples globally minimize their total volume-rather than, for example, surface area or branch length. In addition, the arbors perform well at generating the cheapest topology interconnecting their terminals: their large-scale layouts are among the best of all such possible connecting patterns, approaching 5% of optimum. This model also applies comparably to arterial and river networks.

  8. Voids in the Large-Scale Structure

    NASA Astrophysics Data System (ADS)

    El-Ad, Hagai; Piran, Tsvi

    1997-12-01

    Voids are the most prominent feature of the large-scale structure of the universe. Still, their incorporation into quantitative analysis of it has been relatively recent, owing essentially to the lack of an objective tool to identify the voids and to quantify them. To overcome this, we present here the VOID FINDER algorithm, a novel tool for objectively quantifying voids in the galaxy distribution. The algorithm first classifies galaxies as either wall galaxies or field galaxies. Then, it identifies voids in the wall-galaxy distribution. Voids are defined as continuous volumes that do not contain any wall galaxies. The voids must be thicker than an adjustable limit, which is refined in successive iterations. In this way, we identify the same regions that would be recognized as voids by the eye. Small breaches in the walls are ignored, avoiding artificial connections between neighboring voids. We test the algorithm using Voronoi tesselations. By appropriate scaling of the parameters with the selection function, we apply it to two redshift surveys, the dense SSRS2 and the full-sky IRAS 1.2 Jy. Both surveys show similar properties: ~50% of the volume is filled by voids. The voids have a scale of at least 40 h-1 Mpc and an average -0.9 underdensity. Faint galaxies do not fill the voids, but they do populate them more than bright ones. These results suggest that both optically and IRAS-selected galaxies delineate the same large-scale structure. Comparison with the recovered mass distribution further suggests that the observed voids in the galaxy distribution correspond well to underdense regions in the mass distribution. This confirms the gravitational origin of the voids.

  9. Neutrinos and large-scale structure

    SciTech Connect

    Eisenstein, Daniel J.

    2015-07-15

    I review the use of cosmological large-scale structure to measure properties of neutrinos and other relic populations of light relativistic particles. With experiments to measure the anisotropies of the cosmic microwave anisotropies and the clustering of matter at low redshift, we now have securely measured a relativistic background with density appropriate to the cosmic neutrino background. Our limits on the mass of the neutrino continue to shrink. Experiments coming in the next decade will greatly improve the available precision on searches for the energy density of novel relativistic backgrounds and the mass of neutrinos.

  10. Large-scale planar lightwave circuits

    NASA Astrophysics Data System (ADS)

    Bidnyk, Serge; Zhang, Hua; Pearson, Matt; Balakrishnan, Ashok

    2011-01-01

    By leveraging advanced wafer processing and flip-chip bonding techniques, we have succeeded in hybrid integrating a myriad of active optical components, including photodetectors and laser diodes, with our planar lightwave circuit (PLC) platform. We have combined hybrid integration of active components with monolithic integration of other critical functions, such as diffraction gratings, on-chip mirrors, mode-converters, and thermo-optic elements. Further process development has led to the integration of polarization controlling functionality. Most recently, all these technological advancements have been combined to create large-scale planar lightwave circuits that comprise hundreds of optical elements integrated on chips less than a square inch in size.

  11. Colloquium: Large scale simulations on GPU clusters

    NASA Astrophysics Data System (ADS)

    Bernaschi, Massimo; Bisson, Mauro; Fatica, Massimiliano

    2015-06-01

    Graphics processing units (GPU) are currently used as a cost-effective platform for computer simulations and big-data processing. Large scale applications require that multiple GPUs work together but the efficiency obtained with cluster of GPUs is, at times, sub-optimal because the GPU features are not exploited at their best. We describe how it is possible to achieve an excellent efficiency for applications in statistical mechanics, particle dynamics and networks analysis by using suitable memory access patterns and mechanisms like CUDA streams, profiling tools, etc. Similar concepts and techniques may be applied also to other problems like the solution of Partial Differential Equations.

  12. Large scale phononic metamaterials for seismic isolation

    SciTech Connect

    Aravantinos-Zafiris, N.; Sigalas, M. M.

    2015-08-14

    In this work, we numerically examine structures that could be characterized as large scale phononic metamaterials. These novel structures could have band gaps in the frequency spectrum of seismic waves when their dimensions are chosen appropriately, thus raising the belief that they could be serious candidates for seismic isolation structures. Different and easy to fabricate structures were examined made from construction materials such as concrete and steel. The well-known finite difference time domain method is used in our calculations in order to calculate the band structures of the proposed metamaterials.

  13. Large-scale Heterogeneous Network Data Analysis

    DTIC Science & Technology

    2012-07-31

    Data for Multi-Player Influence Maximization on Social Networks.” KDD 2012 (Demo).  Po-Tzu Chang , Yen-Chieh Huang, Cheng-Lun Yang, Shou-De Lin, Pu...Jen Cheng. “Learning-Based Time-Sensitive Re-Ranking for Web Search.” SIGIR 2012 (poster)  Hung -Che Lai, Cheng-Te Li, Yi-Chen Lo, and Shou-De Lin...Exploiting and Evaluating MapReduce for Large-Scale Graph Mining.” ASONAM 2012 (Full, 16% acceptance ratio).  Hsun-Ping Hsieh , Cheng-Te Li, and Shou

  14. Primer design for large scale sequencing.

    PubMed

    Haas, S; Vingron, M; Poustka, A; Wiemann, S

    1998-06-15

    We have developed PRIDE, a primer design program that automatically designs primers in single contigs or whole sequencing projects to extend the already known sequence and to double strand single-stranded regions. The program is fully integrated into the Staden package (GAP4) and accessible with a graphical user interface. PRIDE uses a fuzzy logic-based system to calculate primer qualities. The computational performance of PRIDE is enhanced by using suffix trees to store the huge amount of data being produced. A test set of 110 sequencing primers and 11 PCR primer pairs has been designed on genomic templates, cDNAs and sequences containing repetitive elements to analyze PRIDE's success rate. The high performance of PRIDE, combined with its minimal requirement of user interaction and its fast algorithm, make this program useful for the large scale design of primers, especially in large sequencing projects.

  15. Large-Scale Organization of Glycosylation Networks

    NASA Astrophysics Data System (ADS)

    Kim, Pan-Jun; Lee, Dong-Yup; Jeong, Hawoong

    2009-03-01

    Glycosylation is a highly complex process to produce a diverse repertoire of cellular glycans that are frequently attached to proteins and lipids. Glycans participate in fundamental biological processes including molecular trafficking and clearance, cell proliferation and apoptosis, developmental biology, immune response, and pathogenesis. N-linked glycans found on proteins are formed by sequential attachments of monosaccharides with the help of a relatively small number of enzymes. Many of these enzymes can accept multiple N-linked glycans as substrates, thus generating a large number of glycan intermediates and their intermingled pathways. Motivated by the quantitative methods developed in complex network research, we investigate the large-scale organization of such N-glycosylation pathways in a mammalian cell. The uncovered results give the experimentally-testable predictions for glycosylation process, and can be applied to the engineering of therapeutic glycoproteins.

  16. Primer design for large scale sequencing.

    PubMed Central

    Haas, S; Vingron, M; Poustka, A; Wiemann, S

    1998-01-01

    We have developed PRIDE, a primer design program that automatically designs primers in single contigs or whole sequencing projects to extend the already known sequence and to double strand single-stranded regions. The program is fully integrated into the Staden package (GAP4) and accessible with a graphical user interface. PRIDE uses a fuzzy logic-based system to calculate primer qualities. The computational performance of PRIDE is enhanced by using suffix trees to store the huge amount of data being produced. A test set of 110 sequencing primers and 11 PCR primer pairs has been designed on genomic templates, cDNAs and sequences containing repetitive elements to analyze PRIDE's success rate. The high performance of PRIDE, combined with its minimal requirement of user interaction and its fast algorithm, make this program useful for the large scale design of primers, especially in large sequencing projects. PMID:9611248

  17. Large scale study of tooth enamel

    SciTech Connect

    Bodart, F.; Deconninck, G.; Martin, M.Th.

    1981-04-01

    Human tooth enamel contains traces of foreign elements. The presence of these elements is related to the history and the environment of the human body and can be considered as the signature of perturbations which occur during the growth of a tooth. A map of the distribution of these traces on a large scale sample of the population will constitute a reference for further investigations of environmental effects. One hundred eighty samples of teeth were first analysed using PIXE, backscattering and nuclear reaction techniques. The results were analysed using statistical methods. Correlations between O, F, Na, P, Ca, Mn, Fe, Cu, Zn, Pb and Sr were observed and cluster analysis was in progress. The techniques described in the present work have been developed in order to establish a method for the exploration of very large samples of the Belgian population.

  18. Large-scale Intelligent Transporation Systems simulation

    SciTech Connect

    Ewing, T.; Canfield, T.; Hannebutte, U.; Levine, D.; Tentner, A.

    1995-06-01

    A prototype computer system has been developed which defines a high-level architecture for a large-scale, comprehensive, scalable simulation of an Intelligent Transportation System (ITS) capable of running on massively parallel computers and distributed (networked) computer systems. The prototype includes the modelling of instrumented ``smart`` vehicles with in-vehicle navigation units capable of optimal route planning and Traffic Management Centers (TMC). The TMC has probe vehicle tracking capabilities (display position and attributes of instrumented vehicles), and can provide 2-way interaction with traffic to provide advisories and link times. Both the in-vehicle navigation module and the TMC feature detailed graphical user interfaces to support human-factors studies. The prototype has been developed on a distributed system of networked UNIX computers but is designed to run on ANL`s IBM SP-X parallel computer system for large scale problems. A novel feature of our design is that vehicles will be represented by autonomus computer processes, each with a behavior model which performs independent route selection and reacts to external traffic events much like real vehicles. With this approach, one will be able to take advantage of emerging massively parallel processor (MPP) systems.

  19. Local gravity and large-scale structure

    NASA Technical Reports Server (NTRS)

    Juszkiewicz, Roman; Vittorio, Nicola; Wyse, Rosemary F. G.

    1990-01-01

    The magnitude and direction of the observed dipole anisotropy of the galaxy distribution can in principle constrain the amount of large-scale power present in the spectrum of primordial density fluctuations. This paper confronts the data, provided by a recent redshift survey of galaxies detected by the IRAS satellite, with the predictions of two cosmological models with very different levels of large-scale power: the biased Cold Dark Matter dominated model (CDM) and a baryon-dominated model (BDM) with isocurvature initial conditions. Model predictions are investigated for the Local Group peculiar velocity, v(R), induced by mass inhomogeneities distributed out to a given radius, R, for R less than about 10,000 km/s. Several convergence measures for v(R) are developed, which can become powerful cosmological tests when deep enough samples become available. For the present data sets, the CDM and BDM predictions are indistinguishable at the 2 sigma level and both are consistent with observations. A promising discriminant between cosmological models is the misalignment angle between v(R) and the apex of the dipole anisotropy of the microwave background.

  20. Large-scale Globally Propagating Coronal Waves.

    PubMed

    Warmuth, Alexander

    Large-scale, globally propagating wave-like disturbances have been observed in the solar chromosphere and by inference in the corona since the 1960s. However, detailed analysis of these phenomena has only been conducted since the late 1990s. This was prompted by the availability of high-cadence coronal imaging data from numerous spaced-based instruments, which routinely show spectacular globally propagating bright fronts. Coronal waves, as these perturbations are usually referred to, have now been observed in a wide range of spectral channels, yielding a wealth of information. Many findings have supported the "classical" interpretation of the disturbances: fast-mode MHD waves or shocks that are propagating in the solar corona. However, observations that seemed inconsistent with this picture have stimulated the development of alternative models in which "pseudo waves" are generated by magnetic reconfiguration in the framework of an expanding coronal mass ejection. This has resulted in a vigorous debate on the physical nature of these disturbances. This review focuses on demonstrating how the numerous observational findings of the last one and a half decades can be used to constrain our models of large-scale coronal waves, and how a coherent physical understanding of these disturbances is finally emerging.

  1. Territorial Polymers and Large Scale Genome Organization

    NASA Astrophysics Data System (ADS)

    Grosberg, Alexander

    2012-02-01

    Chromatin fiber in interphase nucleus represents effectively a very long polymer packed in a restricted volume. Although polymer models of chromatin organization were considered, most of them disregard the fact that DNA has to stay not too entangled in order to function properly. One polymer model with no entanglements is the melt of unknotted unconcatenated rings. Extensive simulations indicate that rings in the melt at large length (monomer numbers) N approach the compact state, with gyration radius scaling as N^1/3, suggesting every ring being compact and segregated from the surrounding rings. The segregation is consistent with the known phenomenon of chromosome territories. Surface exponent β (describing the number of contacts between neighboring rings scaling as N^β) appears only slightly below unity, β 0.95. This suggests that the loop factor (probability to meet for two monomers linear distance s apart) should decay as s^-γ, where γ= 2 - β is slightly above one. The later result is consistent with HiC data on real human interphase chromosomes, and does not contradict to the older FISH data. The dynamics of rings in the melt indicates that the motion of one ring remains subdiffusive on the time scale well above the stress relaxation time.

  2. Introducing Large-Scale Innovation in Schools

    NASA Astrophysics Data System (ADS)

    Sotiriou, Sofoklis; Riviou, Katherina; Cherouvis, Stephanos; Chelioti, Eleni; Bogner, Franz X.

    2016-08-01

    Education reform initiatives tend to promise higher effectiveness in classrooms especially when emphasis is given to e-learning and digital resources. Practical changes in classroom realities or school organization, however, are lacking. A major European initiative entitled Open Discovery Space (ODS) examined the challenge of modernizing school education via a large-scale implementation of an open-scale methodology in using technology-supported innovation. The present paper describes this innovation scheme which involved schools and teachers all over Europe, embedded technology-enhanced learning into wider school environments and provided training to teachers. Our implementation scheme consisted of three phases: (1) stimulating interest, (2) incorporating the innovation into school settings and (3) accelerating the implementation of the innovation. The scheme's impact was monitored for a school year using five indicators: leadership and vision building, ICT in the curriculum, development of ICT culture, professional development support, and school resources and infrastructure. Based on about 400 schools, our study produced four results: (1) The growth in digital maturity was substantial, even for previously high scoring schools. This was even more important for indicators such as vision and leadership" and "professional development." (2) The evolution of networking is presented graphically, showing the gradual growth of connections achieved. (3) These communities became core nodes, involving numerous teachers in sharing educational content and experiences: One out of three registered users (36 %) has shared his/her educational resources in at least one community. (4) Satisfaction scores ranged from 76 % (offer of useful support through teacher academies) to 87 % (good environment to exchange best practices). Initiatives such as ODS add substantial value to schools on a large scale.

  3. Improving Recent Large-Scale Pulsar Surveys

    NASA Astrophysics Data System (ADS)

    Cardoso, Rogerio Fernando; Ransom, S.

    2011-01-01

    Pulsars are unique in that they act as celestial laboratories for precise tests of gravity and other extreme physics (Kramer 2004). There are approximately 2000 known pulsars today, which is less than ten percent of pulsars in the Milky Way according to theoretical models (Lorimer 2004). Out of these 2000 known pulsars, approximately ten percent are known millisecond pulsars, objects used for their period stability for detailed physics tests and searches for gravitational radiation (Lorimer 2008). As the field and instrumentation progress, pulsar astronomers attempt to overcome observational biases and detect new pulsars, consequently discovering new millisecond pulsars. We attempt to improve large scale pulsar surveys by examining three recent pulsar surveys. The first, the Green Bank Telescope 350MHz Drift Scan, a low frequency isotropic survey of the northern sky, has yielded a large number of candidates that were visually inspected and identified, resulting in over 34.000 thousands candidates viewed, dozens of detections of known pulsars, and the discovery of a new low-flux pulsar, PSRJ1911+22. The second, the PALFA survey, is a high frequency survey of the galactic plane with the Arecibo telescope. We created a processing pipeline for the PALFA survey at the National Radio Astronomy Observatory in Charlottesville- VA, in addition to making needed modifications upon advice from the PALFA consortium. The third survey examined is a new GBT 820MHz survey devoted to find new millisecond pulsars by observing the target-rich environment of unidentified sources in the FERMI LAT catalogue. By approaching these three pulsar surveys at different stages, we seek to improve the success rates of large scale surveys, and hence the possibility for ground-breaking work in both basic physics and astrophysics.

  4. Research and Development of Large Area Color AC Plasma Displays

    NASA Astrophysics Data System (ADS)

    Shinoda, Tsutae

    1998-10-01

    Plasma display is essentially a gas discharge device using discharges in small cavities about 0. 1 m. The color plasma displays utilize the visible light from phosphors excited by the ultra-violet by discharge in contrast to monochrome plasma displays utilizing visible light directly from gas discharges. At the early stage of the color plasma display development, the degradation of the phosphors and unstable operating voltage prevented to realize a practical color plasma display. The introduction of the three-electrode surface-discharge technology opened the way to solve the problems. Two key technologies of a simple panel structure with a stripe rib and phosphor alignment and a full color image driving method with an address-and-display-period-separated sub-field method have realized practically available full color plasma displays. A full color plasma display has been firstly developed in 1992 with a 21-in.-diagonal PDP and then a 42-in.-diagonal PDP in 1995 Currently a 50-in.-diagonal color plasma display has been developed. The large area color plasma displays have already been put into the market and are creating new markets, such as a wall hanging TV and multimedia displays for advertisement, information, etc. This paper will show the history of the surface-discharge color plasma display technologies and current status of the color plasma display.

  5. Engineering management of large scale systems

    NASA Technical Reports Server (NTRS)

    Sanders, Serita; Gill, Tepper L.; Paul, Arthur S.

    1989-01-01

    The organization of high technology and engineering problem solving, has given rise to an emerging concept. Reasoning principles for integrating traditional engineering problem solving with system theory, management sciences, behavioral decision theory, and planning and design approaches can be incorporated into a methodological approach to solving problems with a long range perspective. Long range planning has a great potential to improve productivity by using a systematic and organized approach. Thus, efficiency and cost effectiveness are the driving forces in promoting the organization of engineering problems. Aspects of systems engineering that provide an understanding of management of large scale systems are broadly covered here. Due to the focus and application of research, other significant factors (e.g., human behavior, decision making, etc.) are not emphasized but are considered.

  6. Large-scale parametric survival analysis.

    PubMed

    Mittal, Sushil; Madigan, David; Cheng, Jerry Q; Burd, Randall S

    2013-10-15

    Survival analysis has been a topic of active statistical research in the past few decades with applications spread across several areas. Traditional applications usually consider data with only a small numbers of predictors with a few hundreds or thousands of observations. Recent advances in data acquisition techniques and computation power have led to considerable interest in analyzing very-high-dimensional data where the number of predictor variables and the number of observations range between 10(4) and 10(6). In this paper, we present a tool for performing large-scale regularized parametric survival analysis using a variant of the cyclic coordinate descent method. Through our experiments on two real data sets, we show that application of regularized models to high-dimensional data avoids overfitting and can provide improved predictive performance and calibration over corresponding low-dimensional models.

  7. Efficient, large scale separation of coal macerals

    SciTech Connect

    Dyrkacz, G.R.; Bloomquist, C.A.A.

    1988-01-01

    The authors believe that the separation of macerals by continuous flow centrifugation offers a simple technique for the large scale separation of macerals. With relatively little cost (/approximately/ $10K), it provides an opportunity for obtaining quite pure maceral fractions. Although they have not completely worked out all the nuances of this separation system, they believe that the problems they have indicated can be minimized to pose only minor inconvenience. It cannot be said that this system completely bypasses the disagreeable tedium or time involved in separating macerals, nor will it by itself overcome the mental inertia required to make maceral separation an accepted necessary fact in fundamental coal science. However, they find their particular brand of continuous flow centrifugation is considerably faster than sink/float separation, can provide a good quality product with even one separation cycle, and permits the handling of more material than a conventional sink/float centrifuge separation.

  8. Large scale cryogenic fluid systems testing

    NASA Technical Reports Server (NTRS)

    1992-01-01

    NASA Lewis Research Center's Cryogenic Fluid Systems Branch (CFSB) within the Space Propulsion Technology Division (SPTD) has the ultimate goal of enabling the long term storage and in-space fueling/resupply operations for spacecraft and reusable vehicles in support of space exploration. Using analytical modeling, ground based testing, and on-orbit experimentation, the CFSB is studying three primary categories of fluid technology: storage, supply, and transfer. The CFSB is also investigating fluid handling, advanced instrumentation, and tank structures and materials. Ground based testing of large-scale systems is done using liquid hydrogen as a test fluid at the Cryogenic Propellant Tank Facility (K-site) at Lewis' Plum Brook Station in Sandusky, Ohio. A general overview of tests involving liquid transfer, thermal control, pressure control, and pressurization is given.

  9. Grid sensitivity capability for large scale structures

    NASA Technical Reports Server (NTRS)

    Nagendra, Gopal K.; Wallerstein, David V.

    1989-01-01

    The considerations and the resultant approach used to implement design sensitivity capability for grids into a large scale, general purpose finite element system (MSC/NASTRAN) are presented. The design variables are grid perturbations with a rather general linking capability. Moreover, shape and sizing variables may be linked together. The design is general enough to facilitate geometric modeling techniques for generating design variable linking schemes in an easy and straightforward manner. Test cases have been run and validated by comparison with the overall finite difference method. The linking of a design sensitivity capability for shape variables in MSC/NASTRAN with an optimizer would give designers a powerful, automated tool to carry out practical optimization design of real life, complicated structures.

  10. Large Scale Quantum Simulations of Nuclear Pasta

    NASA Astrophysics Data System (ADS)

    Fattoyev, Farrukh J.; Horowitz, Charles J.; Schuetrumpf, Bastian

    2016-03-01

    Complex and exotic nuclear geometries collectively referred to as ``nuclear pasta'' are expected to naturally exist in the crust of neutron stars and in supernovae matter. Using a set of self-consistent microscopic nuclear energy density functionals we present the first results of large scale quantum simulations of pasta phases at baryon densities 0 . 03 < ρ < 0 . 10 fm-3, proton fractions 0 . 05

  11. Modeling the Internet's large-scale topology

    PubMed Central

    Yook, Soon-Hyung; Jeong, Hawoong; Barabási, Albert-László

    2002-01-01

    Network generators that capture the Internet's large-scale topology are crucial for the development of efficient routing protocols and modeling Internet traffic. Our ability to design realistic generators is limited by the incomplete understanding of the fundamental driving forces that affect the Internet's evolution. By combining several independent databases capturing the time evolution, topology, and physical layout of the Internet, we identify the universal mechanisms that shape the Internet's router and autonomous system level topology. We find that the physical layout of nodes form a fractal set, determined by population density patterns around the globe. The placement of links is driven by competition between preferential attachment and linear distance dependence, a marked departure from the currently used exponential laws. The universal parameters that we extract significantly restrict the class of potentially correct Internet models and indicate that the networks created by all available topology generators are fundamentally different from the current Internet. PMID:12368484

  12. Supporting large-scale computational science

    SciTech Connect

    Musick, R., LLNL

    1998-02-19

    Business needs have driven the development of commercial database systems since their inception. As a result, there has been a strong focus on supporting many users, minimizing the potential corruption or loss of data, and maximizing performance metrics like transactions per second, or TPC-C and TPC-D results. It turns out that these optimizations have little to do with the needs of the scientific community, and in particular have little impact on improving the management and use of large-scale high-dimensional data. At the same time, there is an unanswered need in the scientific community for many of the benefits offered by a robust DBMS. For example, tying an ad-hoc query language such as SQL together with a visualization toolkit would be a powerful enhancement to current capabilities. Unfortunately, there has been little emphasis or discussion in the VLDB community on this mismatch over the last decade. The goal of the paper is to identify the specific issues that need to be resolved before large-scale scientific applications can make use of DBMS products. This topic is addressed in the context of an evaluation of commercial DBMS technology applied to the exploration of data generated by the Department of Energy`s Accelerated Strategic Computing Initiative (ASCI). The paper describes the data being generated for ASCI as well as current capabilities for interacting with and exploring this data. The attraction of applying standard DBMS technology to this domain is discussed, as well as the technical and business issues that currently make this an infeasible solution.

  13. Large-scale sequential quadratic programming algorithms

    SciTech Connect

    Eldersveld, S.K.

    1992-09-01

    The problem addressed is the general nonlinear programming problem: finding a local minimizer for a nonlinear function subject to a mixture of nonlinear equality and inequality constraints. The methods studied are in the class of sequential quadratic programming (SQP) algorithms, which have previously proved successful for problems of moderate size. Our goal is to devise an SQP algorithm that is applicable to large-scale optimization problems, using sparse data structures and storing less curvature information but maintaining the property of superlinear convergence. The main features are: 1. The use of a quasi-Newton approximation to the reduced Hessian of the Lagrangian function. Only an estimate of the reduced Hessian matrix is required by our algorithm. The impact of not having available the full Hessian approximation is studied and alternative estimates are constructed. 2. The use of a transformation matrix Q. This allows the QP gradient to be computed easily when only the reduced Hessian approximation is maintained. 3. The use of a reduced-gradient form of the basis for the null space of the working set. This choice of basis is more practical than an orthogonal null-space basis for large-scale problems. The continuity condition for this choice is proven. 4. The use of incomplete solutions of quadratic programming subproblems. Certain iterates generated by an active-set method for the QP subproblem are used in place of the QP minimizer to define the search direction for the nonlinear problem. An implementation of the new algorithm has been obtained by modifying the code MINOS. Results and comparisons with MINOS and NPSOL are given for the new algorithm on a set of 92 test problems.

  14. Large scale mechanical metamaterials as seismic shields

    NASA Astrophysics Data System (ADS)

    Miniaci, Marco; Krushynska, Anastasiia; Bosia, Federico; Pugno, Nicola M.

    2016-08-01

    Earthquakes represent one of the most catastrophic natural events affecting mankind. At present, a universally accepted risk mitigation strategy for seismic events remains to be proposed. Most approaches are based on vibration isolation of structures rather than on the remote shielding of incoming waves. In this work, we propose a novel approach to the problem and discuss the feasibility of a passive isolation strategy for seismic waves based on large-scale mechanical metamaterials, including for the first time numerical analysis of both surface and guided waves, soil dissipation effects, and adopting a full 3D simulations. The study focuses on realistic structures that can be effective in frequency ranges of interest for seismic waves, and optimal design criteria are provided, exploring different metamaterial configurations, combining phononic crystals and locally resonant structures and different ranges of mechanical properties. Dispersion analysis and full-scale 3D transient wave transmission simulations are carried out on finite size systems to assess the seismic wave amplitude attenuation in realistic conditions. Results reveal that both surface and bulk seismic waves can be considerably attenuated, making this strategy viable for the protection of civil structures against seismic risk. The proposed remote shielding approach could open up new perspectives in the field of seismology and in related areas of low-frequency vibration damping or blast protection.

  15. Fully kinetic simulations of megajoule-scale dense plasma focus

    SciTech Connect

    Schmidt, A.; Link, A.; Tang, V.; Halvorson, C.; May, M.; Welch, D.; Meehan, B. T.; Hagen, E. C.

    2014-10-15

    Dense plasma focus (DPF) Z-pinch devices are sources of copious high energy electrons and ions, x-rays, and neutrons. Megajoule-scale DPFs can generate 10{sup 12} neutrons per pulse in deuterium gas through a combination of thermonuclear and beam-target fusion. However, the details of the neutron production are not fully understood and past optimization efforts of these devices have been largely empirical. Previously, we reported on the first fully kinetic simulations of a kilojoule-scale DPF and demonstrated that both kinetic ions and kinetic electrons are needed to reproduce experimentally observed features, such as charged-particle beam formation and anomalous resistivity. Here, we present the first fully kinetic simulation of a MegaJoule DPF, with predicted ion and neutron spectra, neutron anisotropy, neutron spot size, and time history of neutron production. The total yield predicted by the simulation is in agreement with measured values, validating the kinetic model in a second energy regime.

  16. Large-scale wind turbine structures

    NASA Technical Reports Server (NTRS)

    Spera, David A.

    1988-01-01

    The purpose of this presentation is to show how structural technology was applied in the design of modern wind turbines, which were recently brought to an advanced stage of development as sources of renewable power. Wind turbine structures present many difficult problems because they are relatively slender and flexible; subject to vibration and aeroelastic instabilities; acted upon by loads which are often nondeterministic; operated continuously with little maintenance in all weather; and dominated by life-cycle cost considerations. Progress in horizontal-axis wind turbines (HAWT) development was paced by progress in the understanding of structural loads, modeling of structural dynamic response, and designing of innovative structural response. During the past 15 years a series of large HAWTs was developed. This has culminated in the recent completion of the world's largest operating wind turbine, the 3.2 MW Mod-5B power plane installed on the island of Oahu, Hawaii. Some of the applications of structures technology to wind turbine will be illustrated by referring to the Mod-5B design. First, a video overview will be presented to provide familiarization with the Mod-5B project and the important components of the wind turbine system. Next, the structural requirements for large-scale wind turbines will be discussed, emphasizing the difficult fatigue-life requirements. Finally, the procedures used to design the structure will be presented, including the use of the fracture mechanics approach for determining allowable fatigue stresses.

  17. CLASS: The Cosmology Large Angular Scale Surveyor

    NASA Technical Reports Server (NTRS)

    Essinger-Hileman, Thomas; Ali, Aamir; Amiri, Mandana; Appel, John W.; Araujo, Derek; Bennett, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.; Colazo, Felipe; Crowe, Erik; Denis, Kevin; Dunner, Rolando; Eimer, Joseph; Gothe, Dominik; Halpern, Mark; Kogut, Alan J.; Miller, Nathan; Moseley, Samuel; Rostem, Karwan; Stevenson, Thomas; Towner, Deborah; U-Yen, Kongpop; Wollack, Edward

    2014-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravitational wave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array of four telescopes operating from a high-altitude site in the Atacama Desert in Chile. CLASS will survey 70% of the sky in four frequency bands centered at 38, 93, 148, and 217 GHz, which are chosen to straddle the Galactic-foreground minimum while avoiding strong atmospheric emission lines. This broad frequency coverage ensures that CLASS can distinguish Galactic emission from the CMB. The sky fraction of the CLASS survey will allow the full shape of the primordial B-mode power spectrum to be characterized, including the signal from reionization at low-length. Its unique combination of large sky coverage, control of systematic errors, and high sensitivity will allow CLASS to measure or place upper limits on the tensor-to-scalar ratio at a level of r = 0:01 and make a cosmic-variance-limited measurement of the optical depth to the surface of last scattering, tau. (c) (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  18. Large-Scale Spacecraft Fire Safety Tests

    NASA Technical Reports Server (NTRS)

    Urban, David; Ruff, Gary A.; Ferkul, Paul V.; Olson, Sandra; Fernandez-Pello, A. Carlos; T'ien, James S.; Torero, Jose L.; Cowlard, Adam J.; Rouvreau, Sebastien; Minster, Olivier; Toth, Balazs; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu; Jomaas, Grunde

    2014-01-01

    An international collaborative program is underway to address open issues in spacecraft fire safety. Because of limited access to long-term low-gravity conditions and the small volume generally allotted for these experiments, there have been relatively few experiments that directly study spacecraft fire safety under low-gravity conditions. Furthermore, none of these experiments have studied sample sizes and environment conditions typical of those expected in a spacecraft fire. The major constraint has been the size of the sample, with prior experiments limited to samples of the order of 10 cm in length and width or smaller. This lack of experimental data forces spacecraft designers to base their designs and safety precautions on 1-g understanding of flame spread, fire detection, and suppression. However, low-gravity combustion research has demonstrated substantial differences in flame behavior in low-gravity. This, combined with the differences caused by the confined spacecraft environment, necessitates practical scale spacecraft fire safety research to mitigate risks for future space missions. To address this issue, a large-scale spacecraft fire experiment is under development by NASA and an international team of investigators. This poster presents the objectives, status, and concept of this collaborative international project (Saffire). The project plan is to conduct fire safety experiments on three sequential flights of an unmanned ISS re-supply spacecraft (the Orbital Cygnus vehicle) after they have completed their delivery of cargo to the ISS and have begun their return journeys to earth. On two flights (Saffire-1 and Saffire-3), the experiment will consist of a flame spread test involving a meter-scale sample ignited in the pressurized volume of the spacecraft and allowed to burn to completion while measurements are made. On one of the flights (Saffire-2), 9 smaller (5 x 30 cm) samples will be tested to evaluate NASAs material flammability screening tests

  19. Multi-Scale Investigation of Sheared Flows In Magnetized Plasmas

    SciTech Connect

    Edward, Jr., Thomas

    2014-09-19

    Flows parallel and perpendicular to magnetic fields in a plasma are important phenomena in many areas of plasma science research. The presence of these spatially inhomogeneous flows is often associated with the stability of the plasma. In fusion plasmas, these sheared flows can be stabilizing while in space plasmas, these sheared flows can be destabilizing. Because of this, there is broad interest in understanding the coupling between plasma stability and plasma flows. This research project has engaged in a study of the plasma response to spatially inhomogeneous plasma flows using three different experimental devices: the Auburn Linear Experiment for Instability Studies (ALEXIS) and the Compact Toroidal Hybrid (CTH) stellarator devices at Auburn University, and the Space Plasma Simulation Chamber (SPSC) at the Naval Research Laboratory. This work has shown that there is a commonality of the plasma response to sheared flows across a wide range of plasma parameters and magnetic field geometries. The goal of this multi-device, multi-scale project is to understand how sheared flows established by the same underlying physical mechanisms lead to different plasma responses in fusion, laboratory, and space plasmas.

  20. Population generation for large-scale simulation

    NASA Astrophysics Data System (ADS)

    Hannon, Andrew C.; King, Gary; Morrison, Clayton; Galstyan, Aram; Cohen, Paul

    2005-05-01

    Computer simulation is used to research phenomena ranging from the structure of the space-time continuum to population genetics and future combat.1-3 Multi-agent simulations in particular are now commonplace in many fields.4, 5 By modeling populations whose complex behavior emerges from individual interactions, these simulations help to answer questions about effects where closed form solutions are difficult to solve or impossible to derive.6 To be useful, simulations must accurately model the relevant aspects of the underlying domain. In multi-agent simulation, this means that the modeling must include both the agents and their relationships. Typically, each agent can be modeled as a set of attributes drawn from various distributions (e.g., height, morale, intelligence and so forth). Though these can interact - for example, agent height is related to agent weight - they are usually independent. Modeling relations between agents, on the other hand, adds a new layer of complexity, and tools from graph theory and social network analysis are finding increasing application.7, 8 Recognizing the role and proper use of these techniques, however, remains the subject of ongoing research. We recently encountered these complexities while building large scale social simulations.9-11 One of these, the Hats Simulator, is designed to be a lightweight proxy for intelligence analysis problems. Hats models a "society in a box" consisting of many simple agents, called hats. Hats gets its name from the classic spaghetti western, in which the heroes and villains are known by the color of the hats they wear. The Hats society also has its heroes and villains, but the challenge is to identify which color hat they should be wearing based on how they behave. There are three types of hats: benign hats, known terrorists, and covert terrorists. Covert terrorists look just like benign hats but act like terrorists. Population structure can make covert hat identification significantly more

  1. Large-scale tides in general relativity

    NASA Astrophysics Data System (ADS)

    Ip, Hiu Yan; Schmidt, Fabian

    2017-02-01

    Density perturbations in cosmology, i.e. spherically symmetric adiabatic perturbations of a Friedmann-Lemaȋtre-Robertson-Walker (FLRW) spacetime, are locally exactly equivalent to a different FLRW solution, as long as their wavelength is much larger than the sound horizon of all fluid components. This fact is known as the "separate universe" paradigm. However, no such relation is known for anisotropic adiabatic perturbations, which correspond to an FLRW spacetime with large-scale tidal fields. Here, we provide a closed, fully relativistic set of evolutionary equations for the nonlinear evolution of such modes, based on the conformal Fermi (CFC) frame. We show explicitly that the tidal effects are encoded by the Weyl tensor, and are hence entirely different from an anisotropic Bianchi I spacetime, where the anisotropy is sourced by the Ricci tensor. In order to close the system, certain higher derivative terms have to be dropped. We show that this approximation is equivalent to the local tidal approximation of Hui and Bertschinger [1]. We also show that this very simple set of equations matches the exact evolution of the density field at second order, but fails at third and higher order. This provides a useful, easy-to-use framework for computing the fully relativistic growth of structure at second order.

  2. Large-scale autostereoscopic outdoor display

    NASA Astrophysics Data System (ADS)

    Reitterer, Jörg; Fidler, Franz; Saint Julien-Wallsee, Ferdinand; Schmid, Gerhard; Gartner, Wolfgang; Leeb, Walter; Schmid, Ulrich

    2013-03-01

    State-of-the-art autostereoscopic displays are often limited in size, effective brightness, number of 3D viewing zones, and maximum 3D viewing distances, all of which are mandatory requirements for large-scale outdoor displays. Conventional autostereoscopic indoor concepts like lenticular lenses or parallax barriers cannot simply be adapted for these screens due to the inherent loss of effective resolution and brightness, which would reduce both image quality and sunlight readability. We have developed a modular autostereoscopic multi-view laser display concept with sunlight readable effective brightness, theoretically up to several thousand 3D viewing zones, and maximum 3D viewing distances of up to 60 meters. For proof-of-concept purposes a prototype display with two pixels was realized. Due to various manufacturing tolerances each individual pixel has slightly different optical properties, and hence the 3D image quality of the display has to be calculated stochastically. In this paper we present the corresponding stochastic model, we evaluate the simulation and measurement results of the prototype display, and we calculate the achievable autostereoscopic image quality to be expected for our concept.

  3. Large scale digital atlases in neuroscience

    NASA Astrophysics Data System (ADS)

    Hawrylycz, M.; Feng, D.; Lau, C.; Kuan, C.; Miller, J.; Dang, C.; Ng, L.

    2014-03-01

    Imaging in neuroscience has revolutionized our current understanding of brain structure, architecture and increasingly its function. Many characteristics of morphology, cell type, and neuronal circuitry have been elucidated through methods of neuroimaging. Combining this data in a meaningful, standardized, and accessible manner is the scope and goal of the digital brain atlas. Digital brain atlases are used today in neuroscience to characterize the spatial organization of neuronal structures, for planning and guidance during neurosurgery, and as a reference for interpreting other data modalities such as gene expression and connectivity data. The field of digital atlases is extensive and in addition to atlases of the human includes high quality brain atlases of the mouse, rat, rhesus macaque, and other model organisms. Using techniques based on histology, structural and functional magnetic resonance imaging as well as gene expression data, modern digital atlases use probabilistic and multimodal techniques, as well as sophisticated visualization software to form an integrated product. Toward this goal, brain atlases form a common coordinate framework for summarizing, accessing, and organizing this knowledge and will undoubtedly remain a key technology in neuroscience in the future. Since the development of its flagship project of a genome wide image-based atlas of the mouse brain, the Allen Institute for Brain Science has used imaging as a primary data modality for many of its large scale atlas projects. We present an overview of Allen Institute digital atlases in neuroscience, with a focus on the challenges and opportunities for image processing and computation.

  4. Food appropriation through large scale land acquisitions

    NASA Astrophysics Data System (ADS)

    Rulli, Maria Cristina; D'Odorico, Paolo

    2014-05-01

    The increasing demand for agricultural products and the uncertainty of international food markets has recently drawn the attention of governments and agribusiness firms toward investments in productive agricultural land, mostly in the developing world. The targeted countries are typically located in regions that have remained only marginally utilized because of lack of modern technology. It is expected that in the long run large scale land acquisitions (LSLAs) for commercial farming will bring the technology required to close the existing crops yield gaps. While the extent of the acquired land and the associated appropriation of freshwater resources have been investigated in detail, the amount of food this land can produce and the number of people it could feed still need to be quantified. Here we use a unique dataset of land deals to provide a global quantitative assessment of the rates of crop and food appropriation potentially associated with LSLAs. We show how up to 300-550 million people could be fed by crops grown in the acquired land, should these investments in agriculture improve crop production and close the yield gap. In contrast, about 190-370 million people could be supported by this land without closing of the yield gap. These numbers raise some concern because the food produced in the acquired land is typically exported to other regions, while the target countries exhibit high levels of malnourishment. Conversely, if used for domestic consumption, the crops harvested in the acquired land could ensure food security to the local populations.

  5. Large-scale carbon fiber tests

    NASA Technical Reports Server (NTRS)

    Pride, R. A.

    1980-01-01

    A realistic release of carbon fibers was established by burning a minimum of 45 kg of carbon fiber composite aircraft structural components in each of five large scale, outdoor aviation jet fuel fire tests. This release was quantified by several independent assessments with various instruments developed specifically for these tests. The most likely values for the mass of single carbon fibers released ranged from 0.2 percent of the initial mass of carbon fiber for the source tests (zero wind velocity) to a maximum of 0.6 percent of the initial carbon fiber mass for dissemination tests (5 to 6 m/s wind velocity). Mean fiber lengths for fibers greater than 1 mm in length ranged from 2.5 to 3.5 mm. Mean diameters ranged from 3.6 to 5.3 micrometers which was indicative of significant oxidation. Footprints of downwind dissemination of the fire released fibers were measured to 19.1 km from the fire.

  6. Metal ion implantation for large scale surface modification

    SciTech Connect

    Brown, I.G.

    1992-10-01

    Intense energetic beams of metal ions can be produced by using a metal vapor vacuum arc as the plasma discharge from which the ion beam is formed. We have developed a number of ion sources of this kind and have built a metal ion implantation facility which can produce repetitively pulsed ion beams with mean ion energy up to several hundred key, pulsed beam current of more than an ampere, and time averaged current of several tens of milliamperes delivered onto a downstream target. We've also done some preliminary work on scaling up this technology to very large size. For example, a 50-cm diameter (2000 cm[sup 2]) set of beam formation electrodes was used to produce a pulsed titanium beam with ion current over 7 amperes at a mean ion energy of 100 key. Separately, a dc embodiment has been used to produce a dc titanium ion beam with current over 600 mA, power supply limited in this work, and up to 6 amperes of dc plasma ion current was maintained for over an hour. In a related program we've developed a plasma immersion method for applying thin metallic and compound films in which the added species is atomically mixed to the substrate. By adding a gas flow to the process, well-bonded compound films can also be formed; metallic films and multilayers as well as oxides and nitrides with mixed transition zones some hundreds of angstroms thick have been synthesized. Here we outline these parallel metal-plasma-based research programs and describe the hardware that we've developed and some of the surface modification research that we've done with it.

  7. Large-scale assembly of colloidal particles

    NASA Astrophysics Data System (ADS)

    Yang, Hongta

    This study reports a simple, roll-to-roll compatible coating technology for producing three-dimensional highly ordered colloidal crystal-polymer composites, colloidal crystals, and macroporous polymer membranes. A vertically beveled doctor blade is utilized to shear align silica microsphere-monomer suspensions to form large-area composites in a single step. The polymer matrix and the silica microspheres can be selectively removed to create colloidal crystals and self-standing macroporous polymer membranes. The thickness of the shear-aligned crystal is correlated with the viscosity of the colloidal suspension and the coating speed, and the correlations can be qualitatively explained by adapting the mechanisms developed for conventional doctor blade coating. Five important research topics related to the application of large-scale three-dimensional highly ordered macroporous films by doctor blade coating are covered in this study. The first topic describes the invention in large area and low cost color reflective displays. This invention is inspired by the heat pipe technology. The self-standing macroporous polymer films exhibit brilliant colors which originate from the Bragg diffractive of visible light form the three-dimensional highly ordered air cavities. The colors can be easily changed by tuning the size of the air cavities to cover the whole visible spectrum. When the air cavities are filled with a solvent which has the same refractive index as that of the polymer, the macroporous polymer films become completely transparent due to the index matching. When the solvent trapped in the cavities is evaporated by in-situ heating, the sample color changes back to brilliant color. This process is highly reversible and reproducible for thousands of cycles. The second topic reports the achievement of rapid and reversible vapor detection by using 3-D macroporous photonic crystals. Capillary condensation of a condensable vapor in the interconnected macropores leads to the

  8. Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility.

    PubMed

    Woo, Hyun-Jong; Chung, Kyu-Sun; You, Hyun-Jong; Lee, Myoung-Jae; Lho, Taihyeop; Choh, Kwon Kook; Yoon, Jung-Sik; Jung, Yong Ho; Lee, Bongju; Yoo, Suk Jae; Kwon, Myeon

    2007-10-01

    A Multi-Purpose Plasma (MP(2)) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB(6) (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB(6) (HLA-LaB(6)) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB(6) cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6 x 10(12) cm(-3), while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB(6) cathode with 4 in. diameter in DiPS.

  9. Extreme Scale Computing for First-Principles Plasma Physics Research

    SciTech Connect

    Chang, Choogn-Seock

    2011-10-12

    World superpowers are in the middle of the “Computnik” race. US Department of Energy (and National Nuclear Security Administration) wishes to launch exascale computer systems into the scientific (and national security) world by 2018. The objective is to solve important scientific problems and to predict the outcomes using the most fundamental scientific laws, which would not be possible otherwise. Being chosen into the next “frontier” group can be of great benefit to a scientific discipline. An extreme scale computer system requires different types of algorithms and programming philosophy from those we have been accustomed to. Only a handful of scientific codes are blessed to be capable of scalable usage of today’s largest computers in operation at petascale (using more than 100,000 cores concurrently). Fortunately, a few magnetic fusion codes are competing well in this race using the “first principles” gyrokinetic equations.These codes are beginning to study the fusion plasma dynamics in full-scale realistic diverted device geometry in natural nonlinear multiscale, including the large scale neoclassical and small scale turbulence physics, but excluding some ultra fast dynamics. In this talk, most of the above mentioned topics will be introduced at executive level. Representative properties of the extreme scale computers, modern programming exercises to take advantage of them, and different philosophies in the data flows and analyses will be presented. Examples of the multi-scale multi-physics scientific discoveries made possible by solving the gyrokinetic equations on extreme scale computers will be described. Future directions into “virtual tokamak experiments” will also be discussed.

  10. Scaled-Up Nonequilibrium Air Plasmas

    DTIC Science & Technology

    2009-10-01

    electrode pairs will be tested to increase the plasma volume. In addition, thermionic cathodes (LaCrO3, LaB6) will be examined to enhance the electron...measure the cathode fall in the glow discharge regime. Current density, electric field strength and other important plasma parameters will be...thermal nonequilibrium, and together with electrical discharge characteristics, estimating the electron density and reduced electric field strength (E/N

  11. Analysis of plasma instabilities and verification of the BOUT code for the Large Plasma Device

    SciTech Connect

    Popovich, P.; Carter, T. A.; Friedman, B.; Umansky, M. V.

    2010-10-15

    The properties of linear instabilities in the Large Plasma Device [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] are studied both through analytic calculations and solving numerically a system of linearized collisional plasma fluid equations using the three-dimensional fluid code BOUT[M. Umansky et al., Contrib. Plasma Phys. 180, 887 (2009)], which has been successfully modified to treat cylindrical geometry. Instability drive from plasma pressure gradients and flows is considered, focusing on resistive drift waves and the Kelvin-Helmholtz and rotational interchange instabilities. A general linear dispersion relation for partially ionized collisional plasmas including these modes is derived and analyzed. For Large Plasma Device relevant profiles including strongly driven flows, it is found that all three modes can have comparable growth rates and frequencies. Detailed comparison with solutions of the analytic dispersion relation demonstrates that BOUT accurately reproduces all characteristics of linear modes in this system.

  12. Sensitivity technologies for large scale simulation.

    SciTech Connect

    Collis, Samuel Scott; Bartlett, Roscoe Ainsworth; Smith, Thomas Michael; Heinkenschloss, Matthias; Wilcox, Lucas C.; Hill, Judith C.; Ghattas, Omar; Berggren, Martin Olof; Akcelik, Volkan; Ober, Curtis Curry; van Bloemen Waanders, Bart Gustaaf; Keiter, Eric Richard

    2005-01-01

    Sensitivity analysis is critically important to numerous analysis algorithms, including large scale optimization, uncertainty quantification,reduced order modeling, and error estimation. Our research focused on developing tools, algorithms and standard interfaces to facilitate the implementation of sensitivity type analysis into existing code and equally important, the work was focused on ways to increase the visibility of sensitivity analysis. We attempt to accomplish the first objective through the development of hybrid automatic differentiation tools, standard linear algebra interfaces for numerical algorithms, time domain decomposition algorithms and two level Newton methods. We attempt to accomplish the second goal by presenting the results of several case studies in which direct sensitivities and adjoint methods have been effectively applied, in addition to an investigation of h-p adaptivity using adjoint based a posteriori error estimation. A mathematical overview is provided of direct sensitivities and adjoint methods for both steady state and transient simulations. Two case studies are presented to demonstrate the utility of these methods. A direct sensitivity method is implemented to solve a source inversion problem for steady state internal flows subject to convection diffusion. Real time performance is achieved using novel decomposition into offline and online calculations. Adjoint methods are used to reconstruct initial conditions of a contamination event in an external flow. We demonstrate an adjoint based transient solution. In addition, we investigated time domain decomposition algorithms in an attempt to improve the efficiency of transient simulations. Because derivative calculations are at the root of sensitivity calculations, we have developed hybrid automatic differentiation methods and implemented this approach for shape optimization for gas dynamics using the Euler equations. The hybrid automatic differentiation method was applied to a first

  13. Large Scale, High Resolution, Mantle Dynamics Modeling

    NASA Astrophysics Data System (ADS)

    Geenen, T.; Berg, A. V.; Spakman, W.

    2007-12-01

    To model the geodynamic evolution of plate convergence, subduction and collision and to allow for a connection to various types of observational data, geophysical, geodetical and geological, we developed a 4D (space-time) numerical mantle convection code. The model is based on a spherical 3D Eulerian fem model, with quadratic elements, on top of which we constructed a 3D Lagrangian particle in cell(PIC) method. We use the PIC method to transport material properties and to incorporate a viscoelastic rheology. Since capturing small scale processes associated with localization phenomena require a high resolution, we spend a considerable effort on implementing solvers suitable to solve for models with over 100 million degrees of freedom. We implemented Additive Schwartz type ILU based methods in combination with a Krylov solver, GMRES. However we found that for problems with over 500 thousend degrees of freedom the convergence of the solver degraded severely. This observation is known from the literature [Saad, 2003] and results from the local character of the ILU preconditioner resulting in a poor approximation of the inverse of A for large A. The size of A for which ILU is no longer usable depends on the condition of A and on the amount of fill in allowed for the ILU preconditioner. We found that for our problems with over 5×105 degrees of freedom convergence became to slow to solve the system within an acceptable amount of walltime, one minute, even when allowing for considerable amount of fill in. We also implemented MUMPS and found good scaling results for problems up to 107 degrees of freedom for up to 32 CPU¡¯s. For problems with over 100 million degrees of freedom we implemented Algebraic Multigrid type methods (AMG) from the ML library [Sala, 2006]. Since multigrid methods are most effective for single parameter problems, we rebuild our model to use the SIMPLE method in the Stokes solver [Patankar, 1980]. We present scaling results from these solvers for 3D

  14. Large Scale Flame Spread Environmental Characterization Testing

    NASA Technical Reports Server (NTRS)

    Clayman, Lauren K.; Olson, Sandra L.; Gokoghi, Suleyman A.; Brooker, John E.; Ferkul, Paul V.; Kacher, Henry F.

    2013-01-01

    Under the Advanced Exploration Systems (AES) Spacecraft Fire Safety Demonstration Project (SFSDP), as a risk mitigation activity in support of the development of a large-scale fire demonstration experiment in microgravity, flame-spread tests were conducted in normal gravity on thin, cellulose-based fuels in a sealed chamber. The primary objective of the tests was to measure pressure rise in a chamber as sample material, burning direction (upward/downward), total heat release, heat release rate, and heat loss mechanisms were varied between tests. A Design of Experiments (DOE) method was imposed to produce an array of tests from a fixed set of constraints and a coupled response model was developed. Supplementary tests were run without experimental design to additionally vary select parameters such as initial chamber pressure. The starting chamber pressure for each test was set below atmospheric to prevent chamber overpressure. Bottom ignition, or upward propagating burns, produced rapid acceleratory turbulent flame spread. Pressure rise in the chamber increases as the amount of fuel burned increases mainly because of the larger amount of heat generation and, to a much smaller extent, due to the increase in gaseous number of moles. Top ignition, or downward propagating burns, produced a steady flame spread with a very small flat flame across the burning edge. Steady-state pressure is achieved during downward flame spread as the pressure rises and plateaus. This indicates that the heat generation by the flame matches the heat loss to surroundings during the longer, slower downward burns. One heat loss mechanism included mounting a heat exchanger directly above the burning sample in the path of the plume to act as a heat sink and more efficiently dissipate the heat due to the combustion event. This proved an effective means for chamber overpressure mitigation for those tests producing the most total heat release and thusly was determined to be a feasible mitigation

  15. Synchronization of coupled large-scale Boolean networks

    NASA Astrophysics Data System (ADS)

    Li, Fangfei

    2014-03-01

    This paper investigates the complete synchronization and partial synchronization of two large-scale Boolean networks. First, the aggregation algorithm towards large-scale Boolean network is reviewed. Second, the aggregation algorithm is applied to study the complete synchronization and partial synchronization of large-scale Boolean networks. Finally, an illustrative example is presented to show the efficiency of the proposed results.

  16. Synchronization of coupled large-scale Boolean networks

    SciTech Connect

    Li, Fangfei

    2014-03-15

    This paper investigates the complete synchronization and partial synchronization of two large-scale Boolean networks. First, the aggregation algorithm towards large-scale Boolean network is reviewed. Second, the aggregation algorithm is applied to study the complete synchronization and partial synchronization of large-scale Boolean networks. Finally, an illustrative example is presented to show the efficiency of the proposed results.

  17. Automated workflow for large-scale selected reaction monitoring experiments.

    PubMed

    Malmström, Lars; Malmström, Johan; Selevsek, Nathalie; Rosenberger, George; Aebersold, Ruedi

    2012-03-02

    Targeted proteomics allows researchers to study proteins of interest without being drowned in data from other, less interesting proteins or from redundant or uninformative peptides. While the technique is mostly used for smaller, focused studies, there are several reasons to conduct larger targeted experiments. Automated, highly robust software becomes more important in such experiments. In addition, larger experiments are carried out over longer periods of time, requiring strategies to handle the sometimes large shift in retention time often observed. We present a complete proof-of-principle software stack that automates most aspects of selected reaction monitoring workflows, a targeted proteomics technology. The software allows experiments to be easily designed and carried out. The steps automated are the generation of assays, generation of mass spectrometry driver files and methods files, and the import and analysis of the data. All data are normalized to a common retention time scale, the data are then scored using a novel score model, and the error is subsequently estimated. We also show that selected reaction monitoring can be used for label-free quantification. All data generated are stored in a relational database, and the growing resource further facilitates the design of new experiments. We apply the technology to a large-scale experiment studying how Streptococcus pyogenes remodels its proteome under stimulation of human plasma.

  18. Multitree Algorithms for Large-Scale Astrostatistics

    NASA Astrophysics Data System (ADS)

    March, William B.; Ozakin, Arkadas; Lee, Dongryeol; Riegel, Ryan; Gray, Alexander G.

    2012-03-01

    Common astrostatistical operations. A number of common "subroutines" occur over and over again in the statistical analysis of astronomical data. Some of the most powerful, and computationally expensive, of these additionally share the common trait that they involve distance comparisons between all pairs of data points—or in some cases, all triplets or worse. These include: * All Nearest Neighbors (AllNN): For each query point in a dataset, find the k-nearest neighbors among the points in another dataset—naively O(N2) to compute, for O(N) data points. * n-Point Correlation Functions: The main spatial statistic used for comparing two datasets in various ways—naively O(N2) for the 2-point correlation, O(N3) for the 3-point correlation, etc. * Euclidean Minimum Spanning Tree (EMST): The basis for "single-linkage hierarchical clustering,"the main procedure for generating a hierarchical grouping of the data points at all scales, aka "friends-of-friends"—naively O(N2). * Kernel Density Estimation (KDE): The main method for estimating the probability density function of the data, nonparametrically (i.e., with virtually no assumptions on the functional form of the pdf)—naively O(N2). * Kernel Regression: A powerful nonparametric method for regression, or predicting a continuous target value—naively O(N2). * Kernel Discriminant Analysis (KDA): A powerful nonparametric method for classification, or predicting a discrete class label—naively O(N2). (Note that the "two datasets" may in fact be the same dataset, as in two-point autocorrelations, or the so-called monochromatic AllNN problem, or the leave-one-out cross-validation needed in kernel estimation.) The need for fast algorithms for such analysis subroutines is particularly acute in the modern age of exploding dataset sizes in astronomy. The Sloan Digital Sky Survey yielded hundreds of millions of objects, and the next generation of instruments such as the Large Synoptic Survey Telescope will yield roughly

  19. Inductively coupled plasmas: Optimizing the inductive-coupling efficiency for large-area source design

    SciTech Connect

    Colpo, P.; Meziani, T.; Rossi, F.

    2005-03-01

    An inductively coupled plasma (ICP) source enabling high-density plasma generation was developed for large area processing. Technological difficulties related to the scaling up of the coil antenna, dielectric vacuum window, and gas distribution have been addressed. The proposed solution consists in using a magnetic core to concentrate the magnetic field produced by the antenna. Both are placed within the plasma chamber, and the gas injection is done through the magnetic pole. A 75x72- cm{sup 2} plasma source has been designed based on this solution. First, the electrical operation and coil geometries were optimized. The results show that the use of a low excitation frequency (2 MHz) increases the electrical efficiency of the magnetic core, enabling a higher plasma-density generation than at the classical radio frequency of 13.56 MHz. The antenna configuration providing the better uniformity is composed of three loops connected in parallel. Some tuning inductances in series with each loop were added to balance the rf power, i.e., the plasma density over the reactor area. Deviation from plasma uniformities better than 12% over 60x60 cm{sup 2} were achieved. Preliminary SiO{sub 2} etching experiments with CF{sub 4} gas show that the etching uniformity deviation reaches 7% over 60x60 cm{sup 2} with etching rates larger than 150 nm/min. These results are very promising and open the way to the successful scale-up of ICP sources to large areas.

  20. Plasma response to electron energy filter in large volume plasma device

    SciTech Connect

    Sanyasi, A. K.; Awasthi, L. M.; Mattoo, S. K.; Srivastava, P. K.; Singh, S. K.; Singh, R.; Kaw, P. K.

    2013-12-15

    An electron energy filter (EEF) is embedded in the Large Volume Plasma Device plasma for carrying out studies on excitation of plasma turbulence by a gradient in electron temperature (ETG) described in the paper of Mattoo et al. [S. K. Mattoo et al., Phys. Rev. Lett. 108, 255007 (2012)]. In this paper, we report results on the response of the plasma to the EEF. It is shown that inhomogeneity in the magnetic field of the EEF switches on several physical phenomena resulting in plasma regions with different characteristics, including a plasma region free from energetic electrons, suitable for the study of ETG turbulence. Specifically, we report that localized structures of plasma density, potential, electron temperature, and plasma turbulence are excited in the EEF plasma. It is shown that structures of electron temperature and potential are created due to energy dependence of the electron transport in the filter region. On the other hand, although structure of plasma density has origin in the particle transport but two distinct steps of the density structure emerge from dominance of collisionality in the source-EEF region and of the Bohm diffusion in the EEF-target region. It is argued and experimental evidence is provided for existence of drift like flute Rayleigh-Taylor in the EEF plasma.

  1. Probing large-scale structure with radio observations

    NASA Astrophysics Data System (ADS)

    Brown, Shea D.

    This thesis focuses on detecting magnetized relativistic plasma in the intergalactic medium (IGM) of filamentary large-scale structure (LSS) by observing synchrotron emission emitted by structure formation shocks. Little is known about the IGM beyond the largest clusters of galaxies, and synchrotron emission holds enormous promise as a means of probing magnetic fields and relativistic particle populations in these low density regions. I'll first report on observations taken at the Very Large Array and the Westerbork Synthesis Radio Telescope of the diffuse radio source 0809+39. I use these observations to demonstrate that 0809+39 is likely the first "radio relic" discovered that is not associated with a rich |"X-ray emitting cluster of galaxies. I then demonstrate that an unconventional reprocessing of the NVSS polarization survey can reveal structures on scales from 15' to hundreds of degrees, far larger than the nominal shortest-baseline scale. This yields hundreds of new diffuse sources as well as the identification of a new nearby galactic loop . These observations also highlight the major obstacle that diffuse galactic foreground emission poses for any search for large-scale, low surface- brightness extragalactic emission. I therefore explore the cross-correlation of diffuse radio emission with optical tracers of LSS as a means of statistically detecting the presence of magnetic fields in the low-density regions of the cosmic web. This initial study with the Bonn 1.4 GHz radio survey yields an upper limit of 0.2 mG for large-scale filament magnetic fields. Finally, I report on new Green Bank Telescope and Westerbork Synthesis Radio Telescope observations of the famous Coma cluster of galaxies. Major findings include an extension to the Coma cluster radio relic source 1253+275 which makes its total extent ~2 Mpc, as well as a sharp edge, or "front", on the Western side of the radio halo which shows a strong correlation with merger activity associated with an

  2. Generation of large sheet-like ionospheric plasma irregularities at Arecibo

    NASA Astrophysics Data System (ADS)

    Lee, M. C.; Riddolls, R. J.; Burke, W. J.; Sulzer, M. P.; Kuo, S. P.; Klien, E. M. C.

    Large-scale ionospheric plasma irregularities, generated by O-mode heater waves at Arecibo, are shown for the first time to have “sheet-like” structures. The irregularities are aligned with the magnetic meridional plane and have scale sizes ranging from a few hundred meters to a few kilometers. This interpretation is based on detailed considerations of sequential measurements of radar backscatter power, the controlling magnetic field geometry, and the deduced E × B plasma drift. The alignment of O-mode-generated irregularities with the magnetic meridional plane, and their disappearance during X-mode heating intervals are consistent with predictions of the thermal filamentation instability model.

  3. Investigation of large-area multicoil inductively coupled plasma sources using three-dimensional fluid model

    NASA Astrophysics Data System (ADS)

    Brcka, Jozef

    2016-07-01

    A multi inductively coupled plasma (ICP) system can be used to maintain the plasma uniformity and increase the area processed by a high-density plasma. This article presents a source in two different configurations. The distributed planar multi ICP (DM-ICP) source comprises individual ICP sources that are not overlapped and produce plasma independently. Mutual coupling of the ICPs may affect the distribution of the produced plasma. The integrated multicoil ICP (IMC-ICP) source consists of four low-inductance ICP antennas that are superimposed in an azimuthal manner. The identical geometry of the ICP coils was assumed in this work. Both configurations have highly asymmetric components. A three-dimensional (3D) plasma model of the multicoil ICP configurations with asymmetric features is used to investigate the plasma characteristics in a large chamber and the operation of the sources in inert and reactive gases. The feasibility of the computational calculation, the speed, and the computational resources of the coupled multiphysics solver are investigated in the framework of a large realistic geometry and complex reaction processes. It was determined that additional variables can be used to control large-area plasmas. Both configurations can form a plasma, that azimuthally moves in a controlled manner, the so-called “sweeping mode” (SM) or “polyphase mode” (PPM), and thus they have the potential for large-area and high-density plasma applications. The operation in the azimuthal mode has the potential to adjust the plasma distribution, the reaction chemistry, and increase or modulate the production of the radicals. The intrinsic asymmetry of the individual coils and their combined operation were investigated within a source assembly primarily in argon and CO gases. Limited investigations were also performed on operation in CH4 gas. The plasma parameters and the resulting chemistry are affected by the geometrical relation between individual antennas. The aim of

  4. Validating Large Scale Networks Using Temporary Local Scale Networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA NRCS Soil Climate Analysis Network and NOAA Climate Reference Networks are nationwide meteorological and land surface data networks with soil moisture measurements in the top layers of soil. There is considerable interest in scaling these point measurements to larger scales for validating ...

  5. Large-Scale Processing of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Finn, John; Sridhar, K. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Scale-up difficulties and high energy costs are two of the more important factors that limit the availability of various types of nanotube carbon. While several approaches are known for producing nanotube carbon, the high-powered reactors typically produce nanotubes at rates measured in only grams per hour and operate at temperatures in excess of 1000 C. These scale-up and energy challenges must be overcome before nanotube carbon can become practical for high-consumption structural and mechanical applications. This presentation examines the issues associated with using various nanotube production methods at larger scales, and discusses research being performed at NASA Ames Research Center on carbon nanotube reactor technology.

  6. MicroScale - Atmospheric Pressure Plasmas

    SciTech Connect

    Sankaran, Mohan

    2012-01-25

    Low-temperature plasmas play an essential role in the manufacturing of integrated circuits which are ubiquitous in modern society. In recent years, these top-down approaches to materials processing have reached a physical limit. As a result, alternative approaches to materials processing are being developed that will allow the fabrication of nanoscale materials from the bottom up. The aim of our research is to develop a new class of plasmas, termed “microplasmas” for nanomaterials synthesis. Microplasmas are a special class of plasmas formed in geometries where at least one dimension is less than 1 mm. Plasma confinement leads to several unique properties including high-pressure stability and non-equilibrium that make microplasams suitable for nanomaterials synthesis. Vapor-phase precursors can be dissociated to homogeneously nucleate nanometer-sized metal and alloyed nanoparticles. Alternatively, metal salts dispersed in liquids or polymer films can be electrochemically reduced to form metal nanoparticles. In this talk, I will discuss these topics in detail, highlighting the advantages of microplasma-based systems for the synthesis of well-defined nanomaterials.

  7. Two-fluid biasing simulations of the large plasma device

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin M.; Rogers, Barrett N.

    2017-02-01

    External biasing of the Large Plasma Device (LAPD) and its impact on plasma flows and turbulence are explored for the first time in 3D simulations using the Global Braginskii Solver code. Without external biasing, the LAPD plasma spontaneously rotates in the ion diamagnetic direction. The application of a positive bias increases the plasma rotation in the simulations, which show the emergence of a coherent Kelvin Helmholtz (KH) mode outside of the cathode edge with poloidal mode number m ≃ 6 . Negative biasing reduces the rotation in the simulations, which exhibit KH turbulence modestly weaker than but otherwise similar to unbiased simulations. Biasing either way, but especially positively, forces the plasma potential inside the cathode edge to a spatially constant, KH-stable profile, leading to a more quiescent core plasma than the unbiased case. A moderate increase in plasma confinement and an associated steepening of the profiles are seen in the biasing runs. The simulations thus show that the application of external biasing can improve confinement while also driving a Kelvin-Helmholtz instability. Ion-neutral collisions have only a weak effect in the biased or unbiased simulations.

  8. Large scale structure from viscous dark matter

    SciTech Connect

    Blas, Diego; Floerchinger, Stefan; Garny, Mathias; Tetradis, Nikolaos; Wiedemann, Urs Achim E-mail: stefan.floerchinger@cern.ch E-mail: ntetrad@phys.uoa.gr

    2015-11-01

    Cosmological perturbations of sufficiently long wavelength admit a fluid dynamic description. We consider modes with wavevectors below a scale k{sub m} for which the dynamics is only mildly non-linear. The leading effect of modes above that scale can be accounted for by effective non-equilibrium viscosity and pressure terms. For mildly non-linear scales, these mainly arise from momentum transport within the ideal and cold but inhomogeneous fluid, while momentum transport due to more microscopic degrees of freedom is suppressed. As a consequence, concrete expressions with no free parameters, except the matching scale k{sub m}, can be derived from matching evolution equations to standard cosmological perturbation theory. Two-loop calculations of the matter power spectrum in the viscous theory lead to excellent agreement with N-body simulations up to scales k=0.2 h/Mpc. The convergence properties in the ultraviolet are better than for standard perturbation theory and the results are robust with respect to variations of the matching scale.

  9. Large scale structure from viscous dark matter

    NASA Astrophysics Data System (ADS)

    Blas, Diego; Floerchinger, Stefan; Garny, Mathias; Tetradis, Nikolaos; Wiedemann, Urs Achim

    2015-11-01

    Cosmological perturbations of sufficiently long wavelength admit a fluid dynamic description. We consider modes with wavevectors below a scale km for which the dynamics is only mildly non-linear. The leading effect of modes above that scale can be accounted for by effective non-equilibrium viscosity and pressure terms. For mildly non-linear scales, these mainly arise from momentum transport within the ideal and cold but inhomogeneous fluid, while momentum transport due to more microscopic degrees of freedom is suppressed. As a consequence, concrete expressions with no free parameters, except the matching scale km, can be derived from matching evolution equations to standard cosmological perturbation theory. Two-loop calculations of the matter power spectrum in the viscous theory lead to excellent agreement with N-body simulations up to scales k=0.2 h/Mpc. The convergence properties in the ultraviolet are better than for standard perturbation theory and the results are robust with respect to variations of the matching scale.

  10. Global Behavior in Large Scale Systems

    DTIC Science & Technology

    2013-12-05

    Sinopoli, and J. Moura, “ Distributed detection over time varying networks: Large deviations analysis,” in Communication, Control , and Computing...and J. Moura, “ Distributed detection via gaussian running consensus : Large deviations asymptotic analysis,” Signal Processing, IEEE Transactions on... Distributed detection via Gaussian running consensus : large deviations asymptotic analysis,” IEEE Transactions on Signal Processing, vol. 59, no. 9, pp

  11. Long-pulse plasma discharge on the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Kumazawa, R.; Mutoh, T.; Saito, K.; Seki, T.; Nakamura, Y.; Kubo, S.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Ohkubo, K.; Takeiri, Y.; Oka, Y.; Tsumori, K.; Osakabe, M.; Ikeda, K.; Nagaoka, K.; Kaneko, O.; Miyazawa, J.; Morita, S.; Narihara, K.; Shoji, M.; Masuzaki, S.; Kobayashi, M.; Ogawa, H.; Goto, M.; Morisaki, T.; Peterson, B. J.; Sato, K.; Tokuzawa, T.; Ashikawa, N.; Nishimura, K.; Funaba, H.; Chikaraishi, H.; Watari, T.; Watanabe, T.; Sakamoto, M.; Ichimura, M.; Takase, Y.; Notake, T.; Takeuchi, N.; Torii, Y.; Shimpo, F.; Nomura, G.; Takahashi, C.; Yokota, M.; Kato, A.; Zhao, Y.; Kwak, J. G.; Yoon, J. S.; Yamada, H.; Kawahata, K.; Ohyabu, N.; Ida, K.; Nagayama, Y.; Noda, N.; Komori, A.; Sudo, S.; Motojima, O.; LHD experiment Group

    2006-03-01

    A long-pulse plasma discharge of more than 30 min duration was achieved on the Large Helical Device (LHD). A plasma of ne = 0.8 × 1019 m-3 and Ti0 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. The total injected heating energy was 1.3 GJ. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by sweeping the magnetic axis inward and outward. Causes limiting the long pulse plasma discharge are discussed. An ion impurity penetration limited further long-pulse discharge in the 8th experimental campaign (2004).

  12. Subgrid-scale modeling for the study of compressible magnetohydrodynamic turbulence in space plasmas

    NASA Astrophysics Data System (ADS)

    Chernyshov, A. A.; Karelsky, K. V.; Petrosyan, A. S.

    2014-05-01

    A state-of-the-art review is given of research by computing physics methods on compressible magnetohydrodynamic turbulence in space plasmas. The presence of magnetic fields and compressibility in this case makes space plasma turbulence much less amenable to direct numerical simulations than a neutral incompressible fluid. The large eddy simulation method is discussed, which was developed as an alternative to direct modeling and which filters the initial magnetohydrodynamic equations and uses the subgrid-scale modeling of universal small-scale turbulence. A detailed analysis is made of both the method itself and different subgrid-scale parametrizations for compressible magnetohydrodynamic turbulent flows in polytropic and heat-conducting plasmas. The application of subgrid-scale modeling to study turbulence in the local interstellar medium and the scale-invariant spectra of magnetohydrodynamic turbulence are discussed.

  13. On the scaling of small-scale jet noise to large scale

    NASA Astrophysics Data System (ADS)

    Soderman, Paul T.; Allen, Christopher S.

    An examination was made of several published jet noise studies for the purpose of evaluating scale effects important to the simulation of jet aeroacoustics. Several studies confirmed that small conical jets, one as small as 59 mm diameter, could be used to correctly simulate the overall or PNL noise of large jets dominated by mixing noise. However, the detailed acoustic spectra of large jets are more difficult to simulate because of the lack of broad-band turbulence spectra in small jets. One study indicated that a jet Reynolds number of 5 x 10 exp 6 based on exhaust diameter enabled the generation of broad-band noise representative of large jet mixing noise. Jet suppressor aeroacoustics is even more difficult to simulate at small scale because of the small mixer nozzles with flows sensitive to Reynolds number. Likewise, one study showed incorrect ejector mixing and entrainment using small-scale, short ejector that led to poor acoustic scaling. Conversely, fairly good results were found with a longer ejector and, in a different study, with a 32-chute suppressor nozzle. Finally, it was found that small-scale aeroacoustic resonance produced by jets impacting ground boards does not reproduce at large scale.

  14. On the scaling of small-scale jet noise to large scale

    NASA Astrophysics Data System (ADS)

    Soderman, Paul T.; Allen, Christopher S.

    1992-05-01

    An examination was made of several published jet noise studies for the purpose of evaluating scale effects important to the simulation of jet aeroacoustics. Several studies confirmed that small conical jets, one as small as 59 mm diameter, could be used to correctly simulate the overall or perceived noise level (PNL) noise of large jets dominated by mixing noise. However, the detailed acoustic spectra of large jets are more difficult to simulate because of the lack of broad-band turbulence spectra in small jets. One study indicated that a jet Reynolds number of 5 x 10(exp 6) based on exhaust diameter enabled the generation of broad-band noise representative of large jet mixing noise. Jet suppressor aeroacoustics is even more difficult to simulate at small scale because of the small mixer nozzles with flows sensitive to Reynolds number. Likewise, one study showed incorrect ejector mixing and entrainment using a small-scale, short ejector that led to poor acoustic scaling. Conversely, fairly good results were found with a longer ejector and, in a different study, with a 32-chute suppressor nozzle. Finally, it was found that small-scale aeroacoustic resonance produced by jets impacting ground boards does not reproduce at large scale.

  15. On the scaling of small-scale jet noise to large scale

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Allen, Christopher S.

    1992-01-01

    An examination was made of several published jet noise studies for the purpose of evaluating scale effects important to the simulation of jet aeroacoustics. Several studies confirmed that small conical jets, one as small as 59 mm diameter, could be used to correctly simulate the overall or PNL noise of large jets dominated by mixing noise. However, the detailed acoustic spectra of large jets are more difficult to simulate because of the lack of broad-band turbulence spectra in small jets. One study indicated that a jet Reynolds number of 5 x 10 exp 6 based on exhaust diameter enabled the generation of broad-band noise representative of large jet mixing noise. Jet suppressor aeroacoustics is even more difficult to simulate at small scale because of the small mixer nozzles with flows sensitive to Reynolds number. Likewise, one study showed incorrect ejector mixing and entrainment using small-scale, short ejector that led to poor acoustic scaling. Conversely, fairly good results were found with a longer ejector and, in a different study, with a 32-chute suppressor nozzle. Finally, it was found that small-scale aeroacoustic resonance produced by jets impacting ground boards does not reproduce at large scale.

  16. On the scaling of small-scale jet noise to large scale

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Allen, Christopher S.

    1992-01-01

    An examination was made of several published jet noise studies for the purpose of evaluating scale effects important to the simulation of jet aeroacoustics. Several studies confirmed that small conical jets, one as small as 59 mm diameter, could be used to correctly simulate the overall or perceived noise level (PNL) noise of large jets dominated by mixing noise. However, the detailed acoustic spectra of large jets are more difficult to simulate because of the lack of broad-band turbulence spectra in small jets. One study indicated that a jet Reynolds number of 5 x 10(exp 6) based on exhaust diameter enabled the generation of broad-band noise representative of large jet mixing noise. Jet suppressor aeroacoustics is even more difficult to simulate at small scale because of the small mixer nozzles with flows sensitive to Reynolds number. Likewise, one study showed incorrect ejector mixing and entrainment using a small-scale, short ejector that led to poor acoustic scaling. Conversely, fairly good results were found with a longer ejector and, in a different study, with a 32-chute suppressor nozzle. Finally, it was found that small-scale aeroacoustic resonance produced by jets impacting ground boards does not reproduce at large scale.

  17. A large volume uniform plasma generator for the experiments of electromagnetic wave propagation in plasma

    SciTech Connect

    Yang Min; Li Xiaoping; Xie Kai; Liu Donglin; Liu Yanming

    2013-01-15

    A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a 'black out' phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm Multiplication-Sign 260 mm Multiplication-Sign 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.

  18. Plasma graviton production in TeV-scale gravity

    NASA Astrophysics Data System (ADS)

    Melkumova, E. Yu

    2010-11-01

    We develop the theory of interaction of classical plasma with Kaluza-Klein (KK) gravitons in the ADD model of TeV-scale gravity. Plasma is described within the kinetic approach as the system of charged particles and Maxwell field both confined on the brane. Interaction with multidimensional gravity living in the bulk with n compact extra dimensions is introduced within the linearized theory. The KK gravitons emission rates are computed taking into account plasma collective effects through the two-point correlation functions of the fluctuations of the plasma energy-momentum tensor. Apart from known mechanisms (such as bremsstrahlung and gravi-Primakoff effect) we find essentially collective channels such as the coalescence of plasma waves into gravitons which may be manifest in turbulent plasmas. Our results indicate that commonly used rates of the KK gravitons production in stars and supernovae may be underestimated.

  19. Plasma deposited diamond-like carbon films for large neutralarrays

    SciTech Connect

    Brown, I.G.; Blakely, E.A.; Bjornstad, K.A.; Galvin, J.E.; Monteiro, O.R.; Sangyuenyongpipat, S.

    2004-07-15

    To understand how large systems of neurons communicate, we need to develop methods for growing patterned networks of large numbers of neurons. We have found that diamond-like carbon thin films formed by energetic deposition from a filtered vacuum arc carbon plasma can serve as ''neuron friendly'' substrates for the growth of large neural arrays. Lithographic masks can be used to form patterns of diamond-like carbon, and regions of selective neuronal attachment can form patterned neural arrays. In the work described here, we used glass microscope slides as substrates on which diamond-like carbon was deposited. PC-12 rat neurons were then cultured on the treated substrates and cell growth monitored. Neuron growth showed excellent contrast, with prolific growth on the treated surfaces and very low growth on the untreated surfaces. Here we describe the vacuum arc plasma deposition technique employed, and summarize results demonstrating that the approach can be used to form large patterns of neurons.

  20. Very large array faraday rotation studies of the coronal plasma

    NASA Astrophysics Data System (ADS)

    Kooi, Jason Earl

    Knowledge of the coronal magnetic field is crucial for understanding (1) the heating mechanism(s) of the solar corona, (2) the acceleration of the fast solar wind, and (3) the structure and dynamics of coronal mass ejections (CMEs). Observation of Faraday rotation (FR) is one of the best remote-sensing techniques for determining plasma properties in the corona and can provide information on the plasma structure of a CME shortly after launch, shedding light on the initiation process. I used the Karl G. Jansky Very Large Array (VLA) to make sensitive Faraday rotation measurements to investigate the general plasma structure of the corona, properties of coronal plasma inhomogeneities and waves, and transients associated with coronal mass ejections. To enhance my measurements of FR transients, I also developed an algorithm in the Common Astronomy Software Applications (CASA) package to mitigate ionospheric Faraday rotation. In August, 2011, I made FR observations at 5.0 and 6.1 GHz of the radio galaxy 3C 228 through the solar corona at heliocentric distances of 4.6-5.0 solar radii using the VLA. Observations at 5.0 GHz permit measurements deeper in the corona than previous VLA observations at 1.4 and 1.7 GHz. These FR observations provided unique information on the magnetic field in this region of the corona. My data on 3C 228 provide two lines of sight (separated by 46 arcseconds, 33,000 km in the corona). I detected three periods during which there appeared to be a difference in the Faraday rotation measure between these two closely spaced lines of sight, which I used to estimate coronal currents; these values (ranging from 2.6 to 4.1 GA) are several orders of magnitude below that which is necessary for significant coronal heating (assuming the Spitzer resistivity). I also used the data to determine upper limits (3.3 and 6.4 rad/m2 along the two lines of sight) on FR fluctuations caused by coronal waves. These upper limits are comparable to and, thus, not inconsistent

  1. Real or virtual large-scale structure?

    PubMed Central

    Evrard, August E.

    1999-01-01

    Modeling the development of structure in the universe on galactic and larger scales is the challenge that drives the field of computational cosmology. Here, photorealism is used as a simple, yet expert, means of assessing the degree to which virtual worlds succeed in replicating our own. PMID:10200243

  2. Algorithms for Large-Scale Astronomical Problems

    DTIC Science & Technology

    2013-08-01

    release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Modern astronomical datasets are getting larger and larger, which already include...of data, which raises the following question: How can we use modern computer science techniques to help astronomers better analyze large datasets? To...indexing and sorting further reduce the processing time of user queries.  We processed large data using modern distributed computing frameworks

  3. Plasma Sources for Medical Applications - A Comparison of Spot Like Plasmas and Large Area Plasmas

    NASA Astrophysics Data System (ADS)

    Weltmann, Klaus-Dieter

    2015-09-01

    Plasma applications in life science are currently emerging worldwide. Whereas today's commercially available plasma surgical technologies such as argon plasma coagulation (APC) or ablation are mainly based on lethal plasma effects on living systems, the newly emerging therapeutic applications will be based on selective, at least partially non-lethal, possibly stimulating plasma effects on living cells and tissue. Promising results could be obtained by different research groups worldwide revealing a huge potential for the application of low temperature atmospheric pressure plasma in fields such as tissue engineering, healing of chronic wounds, treatment of skin diseases, tumor treatment based on specific induction of apoptotic processes, inhibition of biofilm formation and direct action on biofilms or treatment of dental diseases. The development of suitable and reliable plasma sources for the different therapies requires an in-depth knowledge of their physics, chemistry and parameters. Therefore much basic research still needs to be conducted to minimize risk and to provide a scientific fundament for new plasma-based medical therapies. It is essential to perform a comprehensive assessment of physical and biological experiments to clarify minimum standards for plasma sources for applications in life science and for comparison of different sources. One result is the DIN-SPEC 91315, which is now open for further improvements. This contribution intends to give an overview on the status of commercial cold plasma sources as well as cold plasma sources still under development for medical use. It will discuss needs, prospects and approaches for the characterization of plasmas from different points of view. Regarding the manageability in everyday medical life, atmospheric pressure plasma jets (APPJ) and dielectric barrier discharges (DBD) are of special interest. A comprehensive risk-benefit assessment including the state of the art of commercial sources for medical use

  4. Small-scale plasma irregularities produced during electron attachment chemical releases

    NASA Technical Reports Server (NTRS)

    Scales, W. A.; Bernhardt, P. A.; Ganguli, G.; Siefring, C. L.; Rodriguez, P.

    1994-01-01

    In situ measurements of small-scale plasma density irregularities made during sounding rocket experiments that released electron attachment materials into the ionosphere are presented. A 2D electrostatic simulation model that includes attachment chemistry is used to study the source and evolution of these irregularities. The simulation shows (1) that large electron flow velocity shears develop on the boundary of the electron depletion and (2) these shears drive a plasma instability that is the likely source of the irregularities.

  5. Density profile control in a large diameter, helicon plasma

    SciTech Connect

    Cluggish, B.P.; Anderegg, F.A.; Freeman, R.L.; Gilleland, J.; Hilsabeck, T.J.; Isler, R.C.; Lee, W.D.; Litvak, A.A.; Miller, R.L.; Ohkawa, T.; Putvinski, S.; Umstadter, K.R.; Winslow, D.L.

    2005-05-15

    Plasmas with peaked radial density profiles have been generated in the world's largest helicon device, with plasma diameters of over 70 cm. The density profiles can be manipulated by controlling the phase of the current in each strap of two multistrap antenna arrays. Phase settings that excite long axial wavelengths create hollow density profiles, whereas settings that excite short axial wavelengths create peaked density profiles. This change in density profile is consistent with the cold-plasma dispersion relation for helicon modes, which predicts a strong increase in the effective skin depth of the rf fields as the wavelength decreases. Scaling of the density with magnetic field, gas pressure, and rf power is also presented.

  6. Current Scientific Issues in Large Scale Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Miller, T. L. (Compiler)

    1986-01-01

    Topics in large scale atmospheric dynamics are discussed. Aspects of atmospheric blocking, the influence of transient baroclinic eddies on planetary-scale waves, cyclogenesis, the effects of orography on planetary scale flow, small scale frontal structure, and simulations of gravity waves in frontal zones are discussed.

  7. Large-scale sparse singular value computations

    NASA Technical Reports Server (NTRS)

    Berry, Michael W.

    1992-01-01

    Four numerical methods for computing the singular value decomposition (SVD) of large sparse matrices on a multiprocessor architecture are presented. Lanczos and subspace iteration-based methods for determining several of the largest singular triplets (singular values and corresponding left and right-singular vectors) for sparse matrices arising from two practical applications: information retrieval and seismic reflection tomography are emphasized. The target architectures for implementations are the CRAY-2S/4-128 and Alliant FX/80. The sparse SVD problem is well motivated by recent information-retrieval techniques in which dominant singular values and their corresponding singular vectors of large sparse term-document matrices are desired, and by nonlinear inverse problems from seismic tomography applications which require approximate pseudo-inverses of large sparse Jacobian matrices.

  8. Modified gravity and large scale flows, a review

    NASA Astrophysics Data System (ADS)

    Mould, Jeremy

    2017-02-01

    Large scale flows have been a challenging feature of cosmography ever since galaxy scaling relations came on the scene 40 years ago. The next generation of surveys will offer a serious test of the standard cosmology.

  9. Large-Area Permanent-Magnet ECR Plasma Source

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [<10(exp -4) torr (less than about 1.3 10(exp -2) Pa)] and input power <200 W at a frequency of 2.45 GHz. Though the prototype model operates at 2.45 GHz, operation at higher frequencies can be achieved by straightforward modification to the input microwave waveguide. Higher frequency operation may be desirable in those applications that require even higher background plasma densities. In the design of this ECR plasma source, there are no cumbersome, power-hungry electromagnets. The magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired

  10. Timing signatures of large scale solar eruptions

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Hock-Mysliwiec, Rachel; Henry, Timothy; Kirk, Michael S.

    2016-05-01

    We examine the timing signatures of large solar eruptions resulting in flares, CMEs and Solar Energetic Particle events. We probe solar active regions from the chromosphere through the corona, using data from space and ground-based observations, including ISOON, SDO, GONG, and GOES. Our studies include a number of flares and CMEs of mostly the M- and X-strengths as categorized by GOES. We find that the chromospheric signatures of these large eruptions occur 5-30 minutes in advance of coronal high temperature signatures. These timing measurements are then used as inputs to models and reconstruct the eruptive nature of these systems, and explore their utility in forecasts.

  11. Analyzing large-scale proteomics projects with latent semantic indexing.

    PubMed

    Klie, Sebastian; Martens, Lennart; Vizcaíno, Juan Antonio; Côté, Richard; Jones, Phil; Apweiler, Rolf; Hinneburg, Alexander; Hermjakob, Henning

    2008-01-01

    Since the advent of public data repositories for proteomics data, readily accessible results from high-throughput experiments have been accumulating steadily. Several large-scale projects in particular have contributed substantially to the amount of identifications available to the community. Despite the considerable body of information amassed, very few successful analyses have been performed and published on this data, leveling off the ultimate value of these projects far below their potential. A prominent reason published proteomics data is seldom reanalyzed lies in the heterogeneous nature of the original sample collection and the subsequent data recording and processing. To illustrate that at least part of this heterogeneity can be compensated for, we here apply a latent semantic analysis to the data contributed by the Human Proteome Organization's Plasma Proteome Project (HUPO PPP). Interestingly, despite the broad spectrum of instruments and methodologies applied in the HUPO PPP, our analysis reveals several obvious patterns that can be used to formulate concrete recommendations for optimizing proteomics project planning as well as the choice of technologies used in future experiments. It is clear from these results that the analysis of large bodies of publicly available proteomics data by noise-tolerant algorithms such as the latent semantic analysis holds great promise and is currently underexploited.

  12. Numerically modelling the large scale coronal magnetic field

    NASA Astrophysics Data System (ADS)

    Panja, Mayukh; Nandi, Dibyendu

    2016-07-01

    The solar corona spews out vast amounts of magnetized plasma into the heliosphere which has a direct impact on the Earth's magnetosphere. Thus it is important that we develop an understanding of the dynamics of the solar corona. With our present technology it has not been possible to generate 3D magnetic maps of the solar corona; this warrants the use of numerical simulations to study the coronal magnetic field. A very popular method of doing this, is to extrapolate the photospheric magnetic field using NLFF or PFSS codes. However the extrapolations at different time intervals are completely independent of each other and do not capture the temporal evolution of magnetic fields. On the other hand full MHD simulations of the global coronal field, apart from being computationally very expensive would be physically less transparent, owing to the large number of free parameters that are typically used in such codes. This brings us to the Magneto-frictional model which is relatively simpler and computationally more economic. We have developed a Magnetofrictional Model, in 3D spherical polar co-ordinates to study the large scale global coronal field. Here we present studies of changing connectivities between active regions, in response to photospheric motions.

  13. Cross-scale energy transport in space plasmas

    NASA Astrophysics Data System (ADS)

    Moore, T. W.; Nykyri, K.; Dimmock, A. P.

    2016-12-01

    The solar wind is a supersonic magnetized plasma streaming far into the heliosphere. Although cooling as it flows, it is rapidly heated upon encountering planetary obstacles. At Earth, this interaction forms the magnetosphere and its sub-regions. The present paper focuses on particle heating across the boundary separating the shocked solar wind and magnetospheric plasma, which is driven by mechanisms operating on fluid, ion and electron scales. The cross-scale energy transport between these scales is a compelling and fundamental problem of plasma physics. Here, we present evidence of the energy transport between fluid and ion scales: free energy is provided in terms of a velocity shear generating fluid-scale Kelvin-Helmholtz instability. We show the unambiguous observation of an ion-scale magnetosonic wave packet, inside a Kelvin-Helmholtz vortex, with sufficient energy to account for observed ion heating. The present finding has universal consequences in understanding cross-scale energy transport, applicable to environments experiencing velocity shears during comparable plasma regimes.

  14. Plasma and Ion Sources in Large Area Coatings: A Review

    SciTech Connect

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  15. Linking Large-Scale Reading Assessments: Comment

    ERIC Educational Resources Information Center

    Hanushek, Eric A.

    2016-01-01

    E. A. Hanushek points out in this commentary that applied researchers in education have only recently begun to appreciate the value of international assessments, even though there are now 50 years of experience with these. Until recently, these assessments have been stand-alone surveys that have not been linked, and analysis has largely focused on…

  16. Large scale scientific computing - future directions

    NASA Astrophysics Data System (ADS)

    Patterson, G. S.

    1982-06-01

    Every new generation of scientific computers has opened up new areas of science for exploration through the use of more realistic numerical models or the ability to process ever larger amounts of data. Concomitantly, scientists, because of the success of past models and the wide range of physical phenomena left unexplored, have pressed computer designers to strive for the maximum performance that current technology will permit. This encompasses not only increased processor speed, but also substantial improvements in processor memory, I/O bandwidth, secondary storage and facilities to augment the scientist's ability both to program and to understand the results of a computation. Over the past decade, performance improvements for scientific calculations have come from algoeithm development and a major change in the underlying architecture of the hardware, not from significantly faster circuitry. It appears that this trend will continue for another decade. A future archetectural change for improved performance will most likely be multiple processors coupled together in some fashion. Because the demand for a significantly more powerful computer system comes from users with single large applications, it is essential that an application be efficiently partitionable over a set of processors; otherwise, a multiprocessor system will not be effective. This paper explores some of the constraints on multiple processor architecture posed by these large applications. In particular, the trade-offs between large numbers of slow processors and small numbers of fast processors is examined. Strategies for partitioning range from partitioning at the language statement level (in-the-small) and at the program module level (in-the-large). Some examples of partitioning in-the-large are given and a strategy for efficiently executing a partitioned program is explored.

  17. Mechanisms for multi-scale structures in dense degenerate astrophysical plasmas

    NASA Astrophysics Data System (ADS)

    Shatashvili, N. L.; Mahajan, S. M.; Berezhiani, V. I.

    2016-02-01

    Two distinct routes lead to the creation of multi-scale equilibrium structures in dense degenerate plasmas, often met in astrophysical conditions. By analyzing an e-p-i plasma consisting of degenerate electrons and positrons with a small contamination of mobile classical ions, we show the creation of a new macro scale L_{macro} (controlled by ion concentration). The temperature and degeneracy enhancement effective inertia of bulk e-p components also makes the effective skin depths larger (much larger) than the standard skin depth. The emergence of these intermediate and macro scales lends immense richness to the process of structure formation, and vastly increases the channels for energy transformations. The possible role played by this mechanism in explaining the existence of large-scale structures in astrophysical objects with degenerate plasmas, is examined.

  18. Large-scale preparation of plasmid DNA.

    PubMed

    Heilig, J S; Elbing, K L; Brent, R

    2001-05-01

    Although the need for large quantities of plasmid DNA has diminished as techniques for manipulating small quantities of DNA have improved, occasionally large amounts of high-quality plasmid DNA are desired. This unit describes the preparation of milligram quantities of highly purified plasmid DNA. The first part of the unit describes three methods for preparing crude lysates enriched in plasmid DNA from bacterial cells grown in liquid culture: alkaline lysis, boiling, and Triton lysis. The second part describes four methods for purifying plasmid DNA in such lysates away from contaminating RNA and protein: CsCl/ethidium bromide density gradient centrifugation, polyethylene glycol (PEG) precipitation, anion-exchange chromatography, and size-exclusion chromatography.

  19. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2009-09-30

    9 October and lasting until 1500 UTC, 11 October. (bottom) COAMPS forecast of visibility for the same period showing a dust storm with a similar...starting time and an ending time of 0900 UTC 12 October. (Walker et al., 2009.) 6 7 Figure 3. Comparison of COAMPS dust storm forecast...forecasts of dust storms in areas downwind of the large deserts of the world: Arabian Gulf, Sea of Japan, China Sea, Mediterranean Sea, and the Tropical

  20. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2010-09-30

    advance anywhere on the globe. NAAPS and COAMPS are particularly useful for forecasts of dust storms in areas downwind of the large deserts of the world... dust source regions in NAAPS. The DSD has been crucial for high-resolution dust forecasting in SW Asia using COAMPS (Walker et al., 2009). Dust ...6 Figure 2. Four-panel product used to compare multiple model forecasts of visibility in SW Asia dust storms . On the web the product is

  1. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2007-09-30

    to six days in advance anywhere on the globe. NAAPS and COAMPS are particularly useful for forecasts of dust storms in areas downwind of the large...in FY08. NAAPS forecasts of CONUS dust storms and long-range dust transport to CONUS were further evaluated in collaboration with CSU. These...visibility. The regional model ( COAMPS /Aerosol) became operational during OIF. The global model Navy Aerosol Analysis and Prediction System (NAAPS

  2. The upgraded Large Plasma Device, a machine for studying frontier basic plasma physics.

    PubMed

    Gekelman, W; Pribyl, P; Lucky, Z; Drandell, M; Leneman, D; Maggs, J; Vincena, S; Van Compernolle, B; Tripathi, S K P; Morales, G; Carter, T A; Wang, Y; DeHaas, T

    2016-02-01

    In 1991 a manuscript describing an instrument for studying magnetized plasmas was published in this journal. The Large Plasma Device (LAPD) was upgraded in 2001 and has become a national user facility for the study of basic plasma physics. The upgrade as well as diagnostics introduced since then has significantly changed the capabilities of the device. All references to the machine still quote the original RSI paper, which at this time is not appropriate. In this work, the properties of the updated LAPD are presented. The strategy of the machine construction, the available diagnostics, the parameters available for experiments, as well as illustrations of several experiments are presented here.

  3. On uniform plasma generation for the large area plasma processing in intermediate pressures

    SciTech Connect

    Kim, Hyun Jun; Hwang, Hye-Ju; Cho, Jeong Hee; Chae, Hee Sun; Kim, Dong Hwan; Chung, Chin-Wook

    2015-04-21

    Radial plasma discharge characteristics in the range of 450 mm were studied in a dual inductively coupled plasma (ICP) source, which consisted of a helical ICP and the side type ferrite ICPs. Since the energy relaxation length is shorter than the distance between each of the ferrite ICPs in an intermediate pressure (600 mTorr), local difference in the plasma ignition along the antenna position were observed. In addition, large voltage drop in the discharge of the ferrite ICPs causes an increase in the displacement current to the plasma, and separate discharge mode (E and H mode) according to the antenna position was observed. This results in non-uniform plasma distribution. For the improvement in the discharge of the ferrite ICPs, a capacitor which is placed between the ends of antenna and the ground is adjusted to minimize the displacement current to the plasma. As a result, coincident transitions from E to H mode were observed along the antenna position, and radially concave density profile (edge focused) was measured. For the uniform density distribution, a helical ICP, which located at the center of the discharge chamber, was simultaneously discharged with the ferrite ICPs. Due to the plasma potential variation through the simultaneous discharge of helical ICP and ferrite ICPs, uniform radial distribution in both plasma density and electron temperature are achieved.

  4. Global scale deposition of radioactivity from a large scale exchange

    SciTech Connect

    Knox, J.B.

    1983-10-01

    The global impact of radioactivity pertains to the continental scale and planetary scale deposition of the radioactivity in a delayed mode; it affects all peoples. Global deposition is distinct and separate from close-in fallout. Close-in fallout is delivered in a matter of a few days or less and is much studied in the literature of civilian defense. But much less studied is the matter of global deposition. The global deposition of radioactivity from the reference strategic exchange (5300 MT) leads to an estimated average whole body, total integrated dose of 20 rem for the latitudes of 30 to 50/sup 0/ in the Northern Hemisphere. Hotspots of deposited radioactivity can occur with doses of about 70 rem (winter) to 40 to 110 rem (summer) in regions like Europe, western Asia, western North Pacific, southeastern US, northeastern US, and Canada. The neighboring countries within a few hundred kilometers of areas under strategic nuclear attack can be impacted by the normal (termal close-in) fallout due to gravitational sedimentation with lethal radiation doses to unsheltered populations. In regard to the strategic scenario about 40% of the megatonage is assumed to be in a surface burst mode and the rest in the free air burst mode.

  5. Toward Increasing Fairness in Score Scale Calibrations Employed in International Large-Scale Assessments

    ERIC Educational Resources Information Center

    Oliveri, Maria Elena; von Davier, Matthias

    2014-01-01

    In this article, we investigate the creation of comparable score scales across countries in international assessments. We examine potential improvements to current score scale calibration procedures used in international large-scale assessments. Our approach seeks to improve fairness in scoring international large-scale assessments, which often…

  6. Large-scale GW software development

    NASA Astrophysics Data System (ADS)

    Kim, Minjung; Mandal, Subhasish; Mikida, Eric; Jindal, Prateek; Bohm, Eric; Jain, Nikhil; Kale, Laxmikant; Martyna, Glenn; Ismail-Beigi, Sohrab

    Electronic excitations are important in understanding and designing many functional materials. In terms of ab initio methods, the GW and Bethe-Saltpeter Equation (GW-BSE) beyond DFT methods have proved successful in describing excited states in many materials. However, the heavy computational loads and large memory requirements have hindered their routine applicability by the materials physics community. We summarize some of our collaborative efforts to develop a new software framework designed for GW calculations on massively parallel supercomputers. Our GW code is interfaced with the plane-wave pseudopotential ab initio molecular dynamics software ``OpenAtom'' which is based on the Charm++ parallel library. The computation of the electronic polarizability is one of the most expensive parts of any GW calculation. We describe our strategy that uses a real-space representation to avoid the large number of fast Fourier transforms (FFTs) common to most GW methods. We also describe an eigendecomposition of the plasmon modes from the resulting dielectric matrix that enhances efficiency. This work is supported by NSF through Grant ACI-1339804.

  7. Large-scale profiling of metabolic dysregulation in ovarian cancer.

    PubMed

    Ke, Chaofu; Hou, Yan; Zhang, Haiyu; Fan, Lijun; Ge, Tingting; Guo, Bing; Zhang, Fan; Yang, Kai; Wang, Jingtao; Lou, Ge; Li, Kang

    2015-02-01

    Ovarian cancer is the leading cause of death in gynecologic malignancies. Profiling of endogenous metabolites has potential to identify changes caused by cancer and provide inspiring insights into cancer metabolism. To systematically investigate ovarian cancer metabolism, we performed metabolic profiling of 448 plasma samples related to epithelial ovarian cancer (EOC) based on ultra-performance liquid chromatography mass spectrometry in both positive and negative modes. These unbiased metabolomic profiles could well distinguish EOC from benign ovarian tumor (BOT) and uterine fibroid (UF). Fifty-three metabolites were identified as specific biomarkers for EOC, and this is the first report of piperine, 3-indolepropionic acid, 5-hydroxyindoleacetaldehyde and hydroxyphenyllactate as metabolic biomarkers of EOC. The AUC values of these metabolites for discriminating EOC from BOT/UF and early-stage EOC from BOT/UF were 0.9100/0.9428 and 0.8385/0.8624, respectively. Meanwhile, our metabolites were able to distinguish early-stage EOC from late-stage EOC with an AUC of 0.8801. Importantly, analysis of dysregulated metabolic pathways extends our current understanding of EOC metabolism. Metabolic pathways in EOC patients are mainly characterized by abnormal phospholipid metabolism, altered l-tryptophan catabolism, aggressive fatty acid β-oxidation and aberrant metabolism of piperidine derivatives. Together, these metabolic pathways provide a foundation to support cancer development and progression. In conclusion, our large-scale plasma metabolomics study yielded fundamental insights into dysregulated metabolism in ovarian cancer, which could facilitate clinical diagnosis, therapy, prognosis and shed new lights on ovarian cancer pathogenesis.

  8. Goethite Bench-scale and Large-scale Preparation Tests

    SciTech Connect

    Josephson, Gary B.; Westsik, Joseph H.

    2011-10-23

    The Hanford Waste Treatment and Immobilization Plant (WTP) is the keystone for cleanup of high-level radioactive waste from our nation's nuclear defense program. The WTP will process high-level waste from the Hanford tanks and produce immobilized high-level waste glass for disposal at a national repository, low activity waste (LAW) glass, and liquid effluent from the vitrification off-gas scrubbers. The liquid effluent will be stabilized into a secondary waste form (e.g. grout-like material) and disposed on the Hanford site in the Integrated Disposal Facility (IDF) along with the low-activity waste glass. The major long-term environmental impact at Hanford results from technetium that volatilizes from the WTP melters and finally resides in the secondary waste. Laboratory studies have indicated that pertechnetate ({sup 99}TcO{sub 4}{sup -}) can be reduced and captured into a solid solution of {alpha}-FeOOH, goethite (Um 2010). Goethite is a stable mineral and can significantly retard the release of technetium to the environment from the IDF. The laboratory studies were conducted using reaction times of many days, which is typical of environmental subsurface reactions that were the genesis of this new process. This study was the first step in considering adaptation of the slow laboratory steps to a larger-scale and faster process that could be conducted either within the WTP or within the effluent treatment facility (ETF). Two levels of scale-up tests were conducted (25x and 400x). The largest scale-up produced slurries of Fe-rich precipitates that contained rhenium as a nonradioactive surrogate for {sup 99}Tc. The slurries were used in melter tests at Vitreous State Laboratory (VSL) to determine whether captured rhenium was less volatile in the vitrification process than rhenium in an unmodified feed. A critical step in the technetium immobilization process is to chemically reduce Tc(VII) in the pertechnetate (TcO{sub 4}{sup -}) to Tc(Iv)by reaction with the ferrous

  9. Large Scale Experiments on Spacecraft Fire Safety

    NASA Technical Reports Server (NTRS)

    Urban, David; Ruff, Gary A.; Minster, Olivier; Fernandez-Pello, A. Carlos; Tien, James S.; Torero, Jose L.; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu; Cowlard, Adam J.; Rouvreau, Sebastien; Toth, Balazs; Jomaas, Grunde

    2012-01-01

    Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due to the complexity, cost and risk associated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground-based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame structure. As a result, the prediction of the behaviour of fires in reduced gravity is at present not validated. To address this gap in knowledge, a collaborative international project, Spacecraft Fire Safety, has been established with its cornerstone being the development of an experiment (Fire Safety 1) to be conducted on an ISS resupply vehicle, such as the Automated Transfer Vehicle (ATV) or Orbital Cygnus after it leaves the ISS and before it enters the atmosphere. A computer modelling effort will complement the experimental effort. Although the experiment will need to meet rigorous safety requirements to ensure the carrier vehicle does not sustain damage, the absence of a crew removes the need for strict containment of combustion products. This will facilitate the possibility of examining fire behaviour on a scale that is relevant to spacecraft fire safety and will provide unique data for fire model validation. This unprecedented opportunity will expand the understanding of the fundamentals of fire behaviour in spacecraft. The experiment is being

  10. Large Scale Experiments on Spacecraft Fire Safety

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Ruff, Gary A.; Minster, Olivier; Toth, Balazs; Fernandez-Pello, A. Carlos; T'ien, James S.; Torero, Jose L.; Cowlard, Adam J.; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu; Rouvreau, Sebastien; Jomaas, Grunde

    2012-01-01

    Full scale fire testing complemented by computer modelling has provided significant know how about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due to the complexity, cost and risk associated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground-based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal-gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame structure. As a result, the prediction of the behaviour of fires in reduced gravity is at present not validated. To address this gap in knowledge, a collaborative international project, Spacecraft Fire Safety, has been established with its cornerstone being the development of an experiment (Fire Safety 1) to be conducted on an ISS resupply vehicle, such as the Automated Transfer Vehicle (ATV) or Orbital Cygnus after it leaves the ISS and before it enters the atmosphere. A computer modelling effort will complement the experimental effort. Although the experiment will need to meet rigorous safety requirements to ensure the carrier vehicle does not sustain damage, the absence of a crew removes the need for strict containment of combustion products. This will facilitate the possibility of examining fire behaviour on a scale that is relevant to spacecraft fire safety and will provide unique data for fire model validation. This unprecedented opportunity will expand the understanding of the fundamentals of fire behaviour in spacecraft. The experiment is being

  11. Scaling of the beam plasma discharge for low magnetic fields

    NASA Technical Reports Server (NTRS)

    Papadopoulos, K.

    1986-01-01

    A theoretical analysis of the scaling law and the value of the threshold current for beam plasma discharge (BPD) is presented, based on the requirement for an absolute instability near the plasma frequency. It is shown that both the scaling law as well as the numerical values of Ic are consistent with the experimental data, in the low pressure regimes and for weak magnetic field experiments if the dominant particle loss mechanism is due to Bohm diffusion. The implications of the findings to electron injection in space are discussed.

  12. Relatively scaled ECE temperature profiles of KSTAR plasmas.

    PubMed

    Choi, M J; Yun, G S; Park, H K; Jeon, Y M; Jeong, S H

    2010-10-01

    A scheme to obtain relatively scaled profiles of electron cyclotron emission (ECE) temperature directly from uncalibrated raw radiometer data is proposed and has been tested for the 2009 campaign KSTAR plasmas. The proposed method utilizes a position controlled system to move the plasma adiabatically and compares ECE radiometer channels at the same relative radial positions assuming the profile consistency during the adiabatic change. This scaling method is an alternative solution when an absolute calibration is unreliable or too time consuming. The application to the two dimensional ECE imaging data, wherein calibration is extremely difficult, may also prove to be useful.

  13. Relatively scaled ECE temperature profiles of KSTAR plasmas

    SciTech Connect

    Choi, M. J.; Yun, G. S.; Park, H. K.; Jeon, Y. M.; Jeong, S. H.

    2010-10-15

    A scheme to obtain relatively scaled profiles of electron cyclotron emission (ECE) temperature directly from uncalibrated raw radiometer data is proposed and has been tested for the 2009 campaign KSTAR plasmas. The proposed method utilizes a position controlled system to move the plasma adiabatically and compares ECE radiometer channels at the same relative radial positions assuming the profile consistency during the adiabatic change. This scaling method is an alternative solution when an absolute calibration is unreliable or too time consuming. The application to the two dimensional ECE imaging data, wherein calibration is extremely difficult, may also prove to be useful.

  14. Python for large-scale electrophysiology.

    PubMed

    Spacek, Martin; Blanche, Tim; Swindale, Nicholas

    2008-01-01

    Electrophysiology is increasingly moving towards highly parallel recording techniques which generate large data sets. We record extracellularly in vivo in cat and rat visual cortex with 54-channel silicon polytrodes, under time-locked visual stimulation, from localized neuronal populations within a cortical column. To help deal with the complexity of generating and analysing these data, we used the Python programming language to develop three software projects: one for temporally precise visual stimulus generation ("dimstim"); one for electrophysiological waveform visualization and spike sorting ("spyke"); and one for spike train and stimulus analysis ("neuropy"). All three are open source and available for download (http://swindale.ecc.ubc.ca/code). The requirements and solutions for these projects differed greatly, yet we found Python to be well suited for all three. Here we present our software as a showcase of the extensive capabilities of Python in neuroscience.

  15. Large-Scale Pattern Discovery in Music

    NASA Astrophysics Data System (ADS)

    Bertin-Mahieux, Thierry

    This work focuses on extracting patterns in musical data from very large collections. The problem is split in two parts. First, we build such a large collection, the Million Song Dataset, to provide researchers access to commercial-size datasets. Second, we use this collection to study cover song recognition which involves finding harmonic patterns from audio features. Regarding the Million Song Dataset, we detail how we built the original collection from an online API, and how we encouraged other organizations to participate in the project. The result is the largest research dataset with heterogeneous sources of data available to music technology researchers. We demonstrate some of its potential and discuss the impact it already has on the field. On cover song recognition, we must revisit the existing literature since there are no publicly available results on a dataset of more than a few thousand entries. We present two solutions to tackle the problem, one using a hashing method, and one using a higher-level feature computed from the chromagram (dubbed the 2DFTM). We further investigate the 2DFTM since it has potential to be a relevant representation for any task involving audio harmonic content. Finally, we discuss the future of the dataset and the hope of seeing more work making use of the different sources of data that are linked in the Million Song Dataset. Regarding cover songs, we explain how this might be a first step towards defining a harmonic manifold of music, a space where harmonic similarities between songs would be more apparent.

  16. Large-Scale Structures of Planetary Systems

    NASA Astrophysics Data System (ADS)

    Murray-Clay, Ruth; Rogers, Leslie A.

    2015-12-01

    A class of solar system analogs has yet to be identified among the large crop of planetary systems now observed. However, since most observed worlds are more easily detectable than direct analogs of the Sun's planets, the frequency of systems with structures similar to our own remains unknown. Identifying the range of possible planetary system architectures is complicated by the large number of physical processes that affect the formation and dynamical evolution of planets. I will present two ways of organizing planetary system structures. First, I will suggest that relatively few physical parameters are likely to differentiate the qualitative architectures of different systems. Solid mass in a protoplanetary disk is perhaps the most obvious possible controlling parameter, and I will give predictions for correlations between planetary system properties that we would expect to be present if this is the case. In particular, I will suggest that the solar system's structure is representative of low-metallicity systems that nevertheless host giant planets. Second, the disk structures produced as young stars are fed by their host clouds may play a crucial role. Using the observed distribution of RV giant planets as a function of stellar mass, I will demonstrate that invoking ice lines to determine where gas giants can form requires fine tuning. I will suggest that instead, disk structures built during early accretion have lasting impacts on giant planet distributions, and disk clean-up differentially affects the orbital distributions of giant and lower-mass planets. These two organizational hypotheses have different implications for the solar system's context, and I will suggest observational tests that may allow them to be validated or falsified.

  17. Information Tailoring Enhancements for Large-Scale Social Data

    DTIC Science & Technology

    2016-06-15

    Intelligent Automation Incorporated Information Tailoring Enhancements for Large-Scale...Automation Incorporated Progress Report No. 3 Information Tailoring Enhancements for Large-Scale Social Data Submitted in accordance with...also gathers information about entities from all news articles and displays it on over one million entity pages [5][6], and the information is made

  18. Large-scale societal changes and intentionality - an uneasy marriage.

    PubMed

    Bodor, Péter; Fokas, Nikos

    2014-08-01

    Our commentary focuses on juxtaposing the proposed science of intentional change with facts and concepts pertaining to the level of large populations or changes on a worldwide scale. Although we find a unified evolutionary theory promising, we think that long-term and large-scale, scientifically guided - that is, intentional - social change is not only impossible, but also undesirable.

  19. Large scale static and dynamic friction experiments

    SciTech Connect

    Bakhtar, K.; Barton, N.

    1984-12-31

    A series of nineteen shear tests were performed on fractures 1 m/sup 2/ in area, generated in blocks of sandstone, granite, tuff, hydrostone and concrete. The tests were conducted under quasi-static and dynamic loading conditions. A vertical stress assisted fracturing technique was developed to create the fractures through the large test blocks. Prior to testing, the fractured surface of each block was characterized using the Barton JRC-JCS concept. the results of characterization were used to generate the peak strength envelope for each fractured surface. Attempts were made to model the stress path based on the classical transformation equations which assumes a theoretical plane, elastic isotropic properties, and therefore no slip. However, this approach gave rise to a stress path passing above the strength envelope which is clearly unacceptable. The results of the experimental investigations indicated that actual stress path is affected by the dilatancy due to fracture roughness, as well as by the side friction imposed by the boundary conditions. By introducing the corrections due to the dilation and boundary conditions into the stress transformation equation, the fully corrected stress paths for predicting the strength of fractured blocks were obtained.

  20. Superconducting materials for large scale applications

    SciTech Connect

    Scanlan, Ronald M.; Malozemoff, Alexis P.; Larbalestier, David C.

    2004-05-06

    Significant improvements in the properties ofsuperconducting materials have occurred recently. These improvements arebeing incorporated into the latest generation of wires, cables, and tapesthat are being used in a broad range of prototype devices. These devicesinclude new, high field accelerator and NMR magnets, magnets for fusionpower experiments, motors, generators, and power transmission lines.These prototype magnets are joining a wide array of existing applicationsthat utilize the unique capabilities of superconducting magnets:accelerators such as the Large Hadron Collider, fusion experiments suchas ITER, 930 MHz NMR, and 4 Tesla MRI. In addition, promising newmaterials such as MgB2 have been discovered and are being studied inorder to assess their potential for new applications. In this paper, wewill review the key developments that are leading to these newapplications for superconducting materials. In some cases, the key factoris improved understanding or development of materials with significantlyimproved properties. An example of the former is the development of Nb3Snfor use in high field magnets for accelerators. In other cases, thedevelopment is being driven by the application. The aggressive effort todevelop HTS tapes is being driven primarily by the need for materialsthat can operate at temperatures of 50 K and higher. The implications ofthese two drivers for further developments will be discussed. Finally, wewill discuss the areas where further improvements are needed in order fornew applications to be realized.

  1. Nonlinear large-scale optimization with WORHP

    NASA Astrophysics Data System (ADS)

    Nikolayzik, Tim; Büskens, Christof; Gerdts, Matthias

    Nonlinear optimization has grown to a key technology in many areas of aerospace industry, e.g. satellite control, shape-optimization, aerodynamamics, trajectory planning, reentry prob-lems, interplanetary flights. One of the most extensive areas is the optimization of trajectories for aerospace applications. These problems typically are discretized optimal control problems, which leads to large sparse nonlinear optimization problems. In the end all these different problems from different areas can be described in the general formulation as a nonlinear opti-mization problem. WORHP is designed to solve nonlinear optimization problems with more then one million variables and one million constraints. WORHP uses a lot of different advanced techniques, e.g. reverse communication, to organize the optimization process as efficient and controllable by the user as possible. The solver has nine different interfaces, e.g. to MAT-LAB/SIMULINK and AMPL. Tests of WORHP had shown that WORHP is a very robust and promising solver. Several examples from space applications will be presented.

  2. A Large Scale Virtual Gas Sensor Array

    NASA Astrophysics Data System (ADS)

    Ziyatdinov, Andrey; Fernández-Diaz, Eduard; Chaudry, A.; Marco, Santiago; Persaud, Krishna; Perera, Alexandre

    2011-09-01

    This paper depicts a virtual sensor array that allows the user to generate gas sensor synthetic data while controlling a wide variety of the characteristics of the sensor array response: arbitrary number of sensors, support for multi-component gas mixtures and full control of the noise in the system such as sensor drift or sensor aging. The artificial sensor array response is inspired on the response of 17 polymeric sensors for three analytes during 7 month. The main trends in the synthetic gas sensor array, such as sensitivity, diversity, drift and sensor noise, are user controlled. Sensor sensitivity is modeled by an optionally linear or nonlinear method (spline based). The toolbox on data generation is implemented in open source R language for statistical computing and can be freely accessed as an educational resource or benchmarking reference. The software package permits the design of scenarios with a very large number of sensors (over 10000 sensels), which are employed in the test and benchmarking of neuromorphic models in the Bio-ICT European project NEUROCHEM.

  3. Large-scale structural monitoring systems

    NASA Astrophysics Data System (ADS)

    Solomon, Ian; Cunnane, James; Stevenson, Paul

    2000-06-01

    Extensive structural health instrumentation systems have been installed on three long-span cable-supported bridges in Hong Kong. The quantities measured include environment and applied loads (such as wind, temperature, seismic and traffic loads) and the bridge response to these loadings (accelerations, displacements, and strains). Measurements from over 1000 individual sensors are transmitted to central computing facilities via local data acquisition stations and a fault- tolerant fiber-optic network, and are acquired and processed continuously. The data from the systems is used to provide information on structural load and response characteristics, comparison with design, optimization of inspection, and assurance of continued bridge health. Automated data processing and analysis provides information on important structural and operational parameters. Abnormal events are noted and logged automatically. Information of interest is automatically archived for post-processing. Novel aspects of the instrumentation system include a fluid-based high-accuracy long-span Level Sensing System to measure bridge deck profile and tower settlement. This paper provides an outline of the design and implementation of the instrumentation system. A description of the design and implementation of the data acquisition and processing procedures is also given. Examples of the use of similar systems in monitoring other large structures are discussed.

  4. Large-Scale Magnetic Connectivity in CMEs

    NASA Astrophysics Data System (ADS)

    Zhang, Yuzong; Wang, Jingxiu; Attrill, Gemma; Harra, Louise K.

    Five flare/CME events were selected in this study. One is on May 12, 1997, for which there is only two active regions on the visible solar disc, and the magnetic configuration is rather simple. For other cases, many active regions were visible. They are the flare/CME events that occurred on Bastille Day of 2000, Oct. 28, 2003, Nov. 7, 2004 and Jan. 20, 2005. By tracing the spread of EUV dimming, which was obtained by SOHO/EIT 195 Å fixed-difference images, we studied the CME initiation and development on the solar disc. At the same time we reconstructed the 3D magnetic structure of coronal magnetic fields, extrapolated from the observed photospheric magnetograms by SOHO/MDI. In scrutinizing the EUV brightening and dimming propagation from CME initiation sites to large areas with different magnetic connectivities, we determine the overall coupling and interacting of multiple flux systems in the CME processes. Several typical patterns of magnetic connectivity are described and discussed in the view of CME initiation mechanism or mechanisms.

  5. Impact Cratering Physics al Large Planetary Scales

    NASA Astrophysics Data System (ADS)

    Ahrens, Thomas J.

    2007-06-01

    Present understanding of the physics controlling formation of ˜10^3 km diameter, multi-ringed impact structures on planets were derived from the ideas of Scripps oceanographer, W. Van Dorn, University of London's, W, Murray, and, Caltech's, D. O'Keefe who modeled the vertical oscillations (gravity and elasticity restoring forces) of shock-induced melt and damaged rock within the transient crater immediately after the downward propagating hemispheric shock has processed rock (both lining, and substantially below, the transient cavity crater). The resulting very large surface wave displacements produce the characteristic concentric, multi-ringed basins, as stored energy is radiated away and also dissipated upon inducing further cracking. Initial calculational description, of the above oscillation scenario, has focused upon on properly predicting the resulting density of cracks, and, their orientations. A new numerical version of the Ashby--Sammis crack damage model is coupled to an existing shock hydrodynamics code to predict impact induced damage distributions in a series of 15--70 cm rock targets from high speed impact experiments for a range of impactor type and velocity. These are compared to results of crack damage distributions induced in crustal rocks with small arms impactors and mapped ultrasonically in recent Caltech experiments (Ai and Ahrens, 2006).

  6. Large-scale dynamo growth rates from numerical simulations and implications for mean-field theories.

    PubMed

    Park, Kiwan; Blackman, Eric G; Subramanian, Kandaswamy

    2013-05-01

    Understanding large-scale magnetic field growth in turbulent plasmas in the magnetohydrodynamic limit is a goal of magnetic dynamo theory. In particular, assessing how well large-scale helical field growth and saturation in simulations match those predicted by existing theories is important for progress. Using numerical simulations of isotropically forced turbulence without large-scale shear with its implications, we focus on several additional aspects of this comparison: (1) Leading mean-field dynamo theories which break the field into large and small scales predict that large-scale helical field growth rates are determined by the difference between kinetic helicity and current helicity with no dependence on the nonhelical energy in small-scale magnetic fields. Our simulations show that the growth rate of the large-scale field from fully helical forcing is indeed unaffected by the presence or absence of small-scale magnetic fields amplified in a precursor nonhelical dynamo. However, because the precursor nonhelical dynamo in our simulations produced fields that were strongly subequipartition with respect to the kinetic energy, we cannot yet rule out the potential influence of stronger nonhelical small-scale fields. (2) We have identified two features in our simulations which cannot be explained by the most minimalist versions of two-scale mean-field theory: (i) fully helical small-scale forcing produces significant nonhelical large-scale magnetic energy and (ii) the saturation of the large-scale field growth is time delayed with respect to what minimalist theory predicts. We comment on desirable generalizations to the theory in this context and future desired work.

  7. Large Scale Interconnections Using Dynamic Gratings

    NASA Astrophysics Data System (ADS)

    Pauliat, Gilles; Roosen, Gerald

    1987-01-01

    Optics is attractive for interconnects because the possibility of crossing without any interaction multiple light beams. A crossbar network can be achieved using holographic elements which permit to connect independently all inputs and all outputs. The incorporation of dynamic holographic materials is enticing as this will render the interconnection changeable. However, it is necessary to find first a passive method permitting to achieve beam deflection and secondly a photosensitive material of high optical quality requiring low power levels to optically induce the refractive index changes. We first describe an optical method allowing to produce very large deflections of light beams thus enabling to randomly address any spot on a plane. Such a technique appears applicable to both interconnections of VLSI chips and random access of optical memories. Our scheme for realizing dynamic optical interconnects is based on Bragg diffraction of the beam to steer by a dynamic phase grating which spacing and orientation are changeable in real time. This is achieved in a passive way by acting on the optical frequency of the control beams used to record the dynamic grating. Deflection angles of 15° have been experimentally demonstrated for a 27 nm shift in the control wavelength. For a larger wavelength scanning (50 nm), 28° deflections are anticipated while maintaining the Bragg condition satisfied. We then discuss some issues related to photosensitive materials able to dynamically record the optically induced refractive index change. The specific example of Bi12 Si 020 or Bi12 Ge 020 photorefractive crystals is presented. Indeed these materials are very attractive as they require low driving energy and exhibit a memory effect. This latter property permits to achieve numerous iterations between computing cells before reconfiguration of the interconnect network.

  8. White-Light Polarization and Large-Scale Coronal Structures

    NASA Astrophysics Data System (ADS)

    Badalyan, O. G.; Livshits, M. A.; Sýkora, J.

    1997-06-01

    The results of the white-light polarization measurements performed during three solar eclipses (1973, 1980, 1991) are presented. The eclipse images were processed and analysed by the same technique and method and, consequently, the distributions of the polarization and coronal intensity around the Sun were obtained in unified form for all three solar eclipses. The mutual comparisons of our results, and their comparison with the distributions found by other authors, allowed the real accuracy of the current measurements of the white-light corona polarization, which is not worse than +/-5%, to be estimated. We have investigated the behaviour of the polarization in dependence on heliocentric distance in helmet streamers and coronal holes. Simultaneous interpretation of the data on polarization and intensity in white-light helmet streamers is only possible if a considerable concentration of coronal matter (plasma) towards the plane of the sky is assumed. The values obtained for the coronal hole regions can be understood within the framework of a spherically symmetrical model of the low density solar atmosphere. A tendency towards increasing polarization in coronal holes, connected with the decrease of the hole's size and with the transition from the minimum to the maximum of the solar cycle, was noticed. The problem of how the peculiarities of the large-scale coronal structures are related to the orientation of the global (dipole) solar magnetic field and to the degree of the goffer character of the coronal and interplanetary current sheet is discussed briefly.

  9. Big Data Archives: Replication and synchronizing on a large scale

    NASA Astrophysics Data System (ADS)

    King, T. A.; Walker, R. J.

    2015-12-01

    Modern data archives provide unique challenges to replication and synchronization because of their large size. We collect more digital information today than any time before and the volume of data collected is continuously increasing. Some of these data are from unique observations, like those from planetary missions that should be preserved for use by future generations. In addition data from NASA missions are considered federal records and must be retained. While the data may be stored on resilient hardware (i.e. RAID systems) they also must be protected from local or regional disasters. Meeting this challenge requires creating multiple copies. This task is complicated by the fact that new data are constantly being added creating what are called "active archives". Having reliable, high performance tools for replicating and synchronizing active archives in a timely fashion is critical to preservation of the data. When archives were smaller using tools like bbcp, rsync and rcp worked fairly well. While these tools are affective they are not optimized for synchronizing big data archives and their poor performance at scale lead us to develop a new tool designed specifically for big data archives. It combines the best features of git, bbcp, rsync and rcp. We call this tool "Mimic" and we discuss the design of the tool, performance comparisons and its use at NASA's Planetary Plasma Interactions (PPI) Node of the Planetary Data System (PDS).

  10. Investigation of Coronal Large Scale Structures Utilizing Spartan 201 Data

    NASA Technical Reports Server (NTRS)

    Guhathakurta, Madhulika

    1998-01-01

    Two telescopes aboard Spartan 201, a small satellite has been launched from the Space Shuttles, on April 8th, 1993, September 8th, 1994, September 7th, 1995 and November 20th, 1997. The main objective of the mission was to answer some of the most fundamental unanswered questions of solar physics-What accelerates the solar wind and what heats the corona? The two telescopes are 1) Ultraviolet Coronal Spectrometer (UVCS) provided by the Smithsonian Astrophysical Observatory which uses ultraviolet emissions from neutral hydrogen and ions in the corona to determine velocities of the coronal plasma within the solar wind source region, and the temperature and density distributions of protons and 2) White Light Coronagraph (WLC) provided by NASA's Goddard Space Flight Center which measures visible light to determine the density distribution of coronal electrons within the same region. The PI has had the primary responsibility in the development and application of computer codes necessary for scientific data analysis activities, end instrument calibration for the white-light coronagraph for the entire Spartan mission. The PI was responsible for the science output from the WLC instrument. PI has also been involved in the investigation of coronal density distributions in large-scale structures by use of numerical models which are (mathematically) sufficient to reproduce the details of the observed brightness and polarized brightness distributions found in SPARTAN 201 data.

  11. The energetic coupling of scales in gyrokinetic plasma turbulence

    NASA Astrophysics Data System (ADS)

    Teaca, Bogdan; Navarro, Alejandro Bañón; Jenko, Frank

    2014-07-01

    In magnetized plasma turbulence, the couplings of perpendicular spatial scales that arise due to the nonlinear interactions are analyzed from the perspective of the free-energy exchanges. The plasmas considered here, with appropriate ion or electron adiabatic electro-neutrality responses, are described by the gyrokinetic formalism in a toroidal magnetic geometry. Turbulence develops due to the electrostatic fluctuations driven by temperature gradient instabilities, either ion temperature gradient (ITG) or electron temperature gradient (ETG). The analysis consists in decomposing the system into a series of scale structures, while accounting separately for contributions made by modes possessing special symmetries (e.g., the zonal flow modes). The interaction of these scales is analyzed using the energy transfer functions, including a forward and backward decomposition, scale fluxes, and locality functions. The comparison between the ITG and ETG cases shows that ETG turbulence has a more pronounced classical turbulent behavior, exhibiting a stronger energy cascade, with implications for gyrokinetic turbulence modeling.

  12. The energetic coupling of scales in gyrokinetic plasma turbulence

    SciTech Connect

    Teaca, Bogdan; Jenko, Frank

    2014-07-15

    In magnetized plasma turbulence, the couplings of perpendicular spatial scales that arise due to the nonlinear interactions are analyzed from the perspective of the free-energy exchanges. The plasmas considered here, with appropriate ion or electron adiabatic electro-neutrality responses, are described by the gyrokinetic formalism in a toroidal magnetic geometry. Turbulence develops due to the electrostatic fluctuations driven by temperature gradient instabilities, either ion temperature gradient (ITG) or electron temperature gradient (ETG). The analysis consists in decomposing the system into a series of scale structures, while accounting separately for contributions made by modes possessing special symmetries (e.g., the zonal flow modes). The interaction of these scales is analyzed using the energy transfer functions, including a forward and backward decomposition, scale fluxes, and locality functions. The comparison between the ITG and ETG cases shows that ETG turbulence has a more pronounced classical turbulent behavior, exhibiting a stronger energy cascade, with implications for gyrokinetic turbulence modeling.

  13. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  14. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis Bumpy Torus plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of the NASA Lewis Bumpy Torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power-law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of the potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied include the type of gas, the polarity of the midplane electrode rings (and hence the direction of the radial electric field), the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  15. Large Scale Turbulent Structures in Supersonic Jets

    NASA Technical Reports Server (NTRS)

    Rao, Ram Mohan; Lundgren, Thomas S.

    1997-01-01

    Jet noise is a major concern in the design of commercial aircraft. Studies by various researchers suggest that aerodynamic noise is a major contributor to jet noise. Some of these studies indicate that most of the aerodynamic jet noise due to turbulent mixing occurs when there is a rapid variation in turbulent structure, i.e. rapidly growing or decaying vortices. The objective of this research was to simulate a compressible round jet to study the non-linear evolution of vortices and the resulting acoustic radiations. In particular, to understand the effect of turbulence structure on the noise. An ideal technique to study this problem is Direct Numerical Simulations(DNS), because it provides precise control on the initial and boundary conditions that lead to the turbulent structures studied. It also provides complete 3-dimensional time dependent data. Since the dynamics of a temporally evolving jet are not greatly different from those, of a spatially evolving jet, a temporal jet problem was solved, using periodicity ill the direction of the jet axis. This enables the application of Fourier spectral methods in the streamwise direction. Physically this means that turbulent structures in the jet are repeated in successive downstream cells instead of being gradually modified downstream into a jet plume. The DNS jet simulation helps us understand the various turbulent scales and mechanisms of turbulence generation in the evolution of a compressible round jet. These accurate flow solutions will be used in future research to estimate near-field acoustic radiation by computing the total outward flux across a surface and determine how it is related to the evolution of the turbulent solutions. Furthermore, these simulations allow us to investigate the sensitivity of acoustic radiations to inlet/boundary conditions, with possible application to active noise suppression. In addition, the data generated can be used to compute various turbulence quantities such as mean velocities

  16. Large Scale Turbulent Structures in Supersonic Jets

    NASA Technical Reports Server (NTRS)

    Rao, Ram Mohan; Lundgren, Thomas S.

    1997-01-01

    Jet noise is a major concern in the design of commercial aircraft. Studies by various researchers suggest that aerodynamic noise is a major contributor to jet noise. Some of these studies indicate that most of the aerodynamic jet noise due to turbulent mixing occurs when there is a rapid variation in turbulent structure, i.e. rapidly growing or decaying vortices. The objective of this research was to simulate a compressible round jet to study the non-linear evolution of vortices and the resulting acoustic radiations. In particular, to understand the effect of turbulence structure on the noise. An ideal technique to study this problem is Direct Numerical Simulations (DNS), because it provides precise control on the initial and boundary conditions that lead to the turbulent structures studied. It also provides complete 3-dimensional time dependent data. Since the dynamics of a temporally evolving jet are not greatly different from those of a spatially evolving jet, a temporal jet problem was solved, using periodicity in the direction of the jet axis. This enables the application of Fourier spectral methods in the streamwise direction. Physically this means that turbulent structures in the jet are repeated in successive downstream cells instead of being gradually modified downstream into a jet plume. The DNS jet simulation helps us understand the various turbulent scales and mechanisms of turbulence generation in the evolution of a compressible round jet. These accurate flow solutions will be used in future research to estimate near-field acoustic radiation by computing the total outward flux across a surface and determine how it is related to the evolution of the turbulent solutions. Furthermore, these simulations allow us to investigate the sensitivity of acoustic radiations to inlet/boundary conditions, with possible appli(,a- tion to active noise suppression. In addition, the data generated can be used to compute, various turbulence quantities such as mean

  17. Von-Karman scaling of proton and electron heating in turbulent plasma

    NASA Astrophysics Data System (ADS)

    Parashar, T. N.; Matthaeus, W. H.; Wan, M.; Shay, M. A.

    2015-12-01

    Abstract: A self consistent description of plasma dissipation requires fully kinetic treatment. In recent publications, we have addressed how proton heating depends on large scale parameters [1,2] and how the system size simulated affects the plasma energetics [3]. Here, we study the relative heating of protons and electrons as it depends on large scale parameters. We also discuss the dependence of this relative heating on von-Karman decay rates, along with implications for turbulent dissipation challenge. An interesting possibility is that turbulent heating and heating in reconnection might be understood in a unified way [4]. [1] Wu et al, PRL, 111,121105 (2013) [2] Matthaeus et al, ApJ, 790, 155 (2014) [3] Parashar et al, ApJ (under review)[4] Shay et al, Physics of Plasmas, 21, 122902 (2014)

  18. Distribution probability of large-scale landslides in central Nepal

    NASA Astrophysics Data System (ADS)

    Timilsina, Manita; Bhandary, Netra P.; Dahal, Ranjan Kumar; Yatabe, Ryuichi

    2014-12-01

    Large-scale landslides in the Himalaya are defined as huge, deep-seated landslide masses that occurred in the geological past. They are widely distributed in the Nepal Himalaya. The steep topography and high local relief provide high potential for such failures, whereas the dynamic geology and adverse climatic conditions play a key role in the occurrence and reactivation of such landslides. The major geoscientific problems related with such large-scale landslides are 1) difficulties in their identification and delineation, 2) sources of small-scale failures, and 3) reactivation. Only a few scientific publications have been published concerning large-scale landslides in Nepal. In this context, the identification and quantification of large-scale landslides and their potential distribution are crucial. Therefore, this study explores the distribution of large-scale landslides in the Lesser Himalaya. It provides simple guidelines to identify large-scale landslides based on their typical characteristics and using a 3D schematic diagram. Based on the spatial distribution of landslides, geomorphological/geological parameters and logistic regression, an equation of large-scale landslide distribution is also derived. The equation is validated by applying it to another area. For the new area, the area under the receiver operating curve of the landslide distribution probability in the new area is 0.699, and a distribution probability value could explain > 65% of existing landslides. Therefore, the regression equation can be applied to areas of the Lesser Himalaya of central Nepal with similar geological and geomorphological conditions.

  19. Transport scaling in interchange-driven toroidal plasmas

    SciTech Connect

    Ricci, Paolo; Rogers, B. N.

    2009-06-15

    Two-dimensional fluid simulations of a simple magnetized torus are presented, in which the vertical and toroidal components of the magnetic field create helicoidal field lines that terminate on the upper and lower walls of the plasma chamber. The simulations self-consistently evolve the full radial profiles of the electric potential, density, and electron temperature in the presence of three competing effects: the cross-field turbulent transport driven by the interchange instability, parallel losses to the upper and lower walls, and the input of particles and heat by external plasma sources. Considering parameter regimes in which equilibrium ExB shear flow effects are weak, we study the dependence of the plasma profiles--in particular the pressure profile scale length--on the parameters of the system. Analytical scalings are obtained that show remarkable agreement with the simulations.

  20. Radially dependent large-scale dynamos in global cylindrical shear flows and the local cartesian limit

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Blackman, E. G.

    2016-06-01

    For cylindrical differentially rotating plasmas, we study large-scale magnetic field generation from finite amplitude non-axisymmetric perturbations by comparing numerical simulations with quasi-linear analytic theory. When initiated with a vertical magnetic field of either zero or finite net flux, our global cylindrical simulations exhibit the magnetorotational instability (MRI) and large-scale dynamo growth of radially alternating mean fields, averaged over height and azimuth. This dynamo growth is explained by our analytic calculations of a non-axisymmetric fluctuation-induced electromotive force that is sustained by azimuthal shear of the fluctuating fields. The standard `Ω effect' (shear of the mean field by differential rotation) is unimportant. For the MRI case, we express the large-scale dynamo field as a function of differential rotation. The resulting radially alternating large-scale fields may have implications for angular momentum transport in discs and corona. To connect with previous work on large-scale dynamos with local linear shear and identify the minimum conditions needed for large-scale field growth, we also solve our equations in local Cartesian coordinates. We find that large-scale dynamo growth in a linear shear flow without rotation can be sustained by shear plus non-axisymmetric fluctuations - even if not helical, a seemingly previously unidentified distinction. The linear shear flow dynamo emerges as a more restricted version of our more general new global cylindrical calculations.

  1. A study of MLFMA for large-scale scattering problems

    NASA Astrophysics Data System (ADS)

    Hastriter, Michael Larkin

    This research is centered in computational electromagnetics with a focus on solving large-scale problems accurately in a timely fashion using first principle physics. Error control of the translation operator in 3-D is shown. A parallel implementation of the multilevel fast multipole algorithm (MLFMA) was studied as far as parallel efficiency and scaling. The large-scale scattering program (LSSP), based on the ScaleME library, was used to solve ultra-large-scale problems including a 200lambda sphere with 20 million unknowns. As these large-scale problems were solved, techniques were developed to accurately estimate the memory requirements. Careful memory management is needed in order to solve these massive problems. The study of MLFMA in large-scale problems revealed significant errors that stemmed from inconsistencies in constants used by different parts of the algorithm. These were fixed to produce the most accurate data possible for large-scale surface scattering problems. Data was calculated on a missile-like target using both high frequency methods and MLFMA. This data was compared and analyzed to determine possible strategies to increase data acquisition speed and accuracy through multiple computation method hybridization.

  2. A bibliographical surveys of large-scale systems

    NASA Technical Reports Server (NTRS)

    Corliss, W. R.

    1970-01-01

    A limited, partly annotated bibliography was prepared on the subject of large-scale system control. Approximately 400 references are divided into thirteen application areas, such as large societal systems and large communication systems. A first-author index is provided.

  3. Arc plasma simulation of the KAERI large ion source.

    PubMed

    In, S R; Jeong, S H; Kim, T S

    2008-02-01

    The KAERI large ion source, developed for the KSTAR NBI system, recently produced ion beams of 100 keV, 50 A levels in the first half campaign of 2007. These results seem to be the best performance of the present ion source at a maximum available input power of 145 kW. A slight improvement in the ion source is certainly necessary to attain the final goal of an 8 MW ion beam. Firstly, the experimental results were analyzed to differentiate the cause and effect for the insufficient beam currents. Secondly, a zero dimensional simulation was carried out on the ion source plasma to identify which factors control the arc plasma and to find out what improvements can be expected.

  4. Large-scale velocity structures in turbulent thermal convection.

    PubMed

    Qiu, X L; Tong, P

    2001-09-01

    A systematic study of large-scale velocity structures in turbulent thermal convection is carried out in three different aspect-ratio cells filled with water. Laser Doppler velocimetry is used to measure the velocity profiles and statistics over varying Rayleigh numbers Ra and at various spatial positions across the whole convection cell. Large velocity fluctuations are found both in the central region and near the cell boundary. Despite the large velocity fluctuations, the flow field still maintains a large-scale quasi-two-dimensional structure, which rotates in a coherent manner. This coherent single-roll structure scales with Ra and can be divided into three regions in the rotation plane: (1) a thin viscous boundary layer, (2) a fully mixed central core region with a constant mean velocity gradient, and (3) an intermediate plume-dominated buffer region. The experiment reveals a unique driving mechanism for the large-scale coherent rotation in turbulent convection.

  5. Needs, opportunities, and options for large scale systems research

    SciTech Connect

    Thompson, G.L.

    1984-10-01

    The Office of Energy Research was recently asked to perform a study of Large Scale Systems in order to facilitate the development of a true large systems theory. It was decided to ask experts in the fields of electrical engineering, chemical engineering and manufacturing/operations research for their ideas concerning large scale systems research. The author was asked to distribute a questionnaire among these experts to find out their opinions concerning recent accomplishments and future research directions in large scale systems research. He was also requested to convene a conference which included three experts in each area as panel members to discuss the general area of large scale systems research. The conference was held on March 26--27, 1984 in Pittsburgh with nine panel members, and 15 other attendees. The present report is a summary of the ideas presented and the recommendations proposed by the attendees.

  6. The cold and atmospheric-pressure air surface barrier discharge plasma for large-area sterilization applications

    SciTech Connect

    Wang Dacheng; Zhao Di; Feng Kecheng; Zhang Xianhui; Liu Dongping; Yang Size

    2011-04-18

    This letter reports a stable air surface barrier discharge device for large-area sterilization applications at room temperature. This design may result in visually uniform plasmas with the electrode area scaled up (or down) to the required size. A comparison for the survival rates of Escherichia coli from air, N{sub 2} and O{sub 2} surface barrier discharge plasmas is presented, and the air surface plasma consisting of strong filamentary discharges can efficiently kill Escherichia coli. Optical emission measurements indicate that reactive species such as O and OH generated in the room temperature air plasmas play a significant role in the sterilization process.

  7. Relativistic thermal electron scale instabilities in sheared flow plasma

    NASA Astrophysics Data System (ADS)

    Miller, Evan D.; Rogers, Barrett N.

    2016-04-01

    > The linear dispersion relation obeyed by finite-temperature, non-magnetized, relativistic two-fluid plasmas is presented, in the special case of a discontinuous bulk velocity profile and parallel wave vectors. It is found that such flows become universally unstable at the collisionless electron skin-depth scale. Further analyses are performed in the limits of either free-streaming ions or ultra-hot plasmas. In these limits, the system is highly unstable in the parameter regimes associated with either the electron scale Kelvin-Helmholtz instability (ESKHI) or the relativistic electron scale sheared flow instability (RESI) recently highlighted by Gruzinov. Coupling between these modes provides further instability throughout the remaining parameter space, provided both shear flow and temperature are finite. An explicit parameter space bound on the highly unstable region is found.

  8. Scale analysis of equatorial plasma irregularities derived from Swarm constellation

    NASA Astrophysics Data System (ADS)

    Xiong, Chao; Stolle, Claudia; Lühr, Hermann; Park, Jaeheung; Fejer, Bela G.; Kervalishvili, Guram N.

    2016-07-01

    In this study, we investigated the scale sizes of equatorial plasma irregularities (EPIs) using measurements from the Swarm satellites during its early mission and final constellation phases. We found that with longitudinal separation between Swarm satellites larger than 0.4°, no significant correlation was found any more. This result suggests that EPI structures include plasma density scale sizes less than 44 km in the zonal direction. During the Swarm earlier mission phase, clearly better EPI correlations are obtained in the northern hemisphere, implying more fragmented irregularities in the southern hemisphere where the ambient magnetic field is low. The previously reported inverted-C shell structure of EPIs is generally confirmed by the Swarm observations in the northern hemisphere, but with various tilt angles. From the Swarm spacecrafts with zonal separations of about 150 km, we conclude that larger zonal scale sizes of irregularities exist during the early evening hours (around 1900 LT).

  9. Nonlinear Generation of shear flows and large scale magnetic fields by small scale

    NASA Astrophysics Data System (ADS)

    Aburjania, G.

    2009-04-01

    EGU2009-233 Nonlinear Generation of shear flows and large scale magnetic fields by small scale turbulence in the ionosphere by G. Aburjania Contact: George Aburjania, g.aburjania@gmail.com,aburj@mymail.ge

  10. Large scale purification of RNA nanoparticles by preparative ultracentrifugation.

    PubMed

    Jasinski, Daniel L; Schwartz, Chad T; Haque, Farzin; Guo, Peixuan

    2015-01-01

    Purification of large quantities of supramolecular RNA complexes is of paramount importance due to the large quantities of RNA needed and the purity requirements for in vitro and in vivo assays. Purification is generally carried out by liquid chromatography (HPLC), polyacrylamide gel electrophoresis (PAGE), or agarose gel electrophoresis (AGE). Here, we describe an efficient method for the large-scale purification of RNA prepared by in vitro transcription using T7 RNA polymerase by cesium chloride (CsCl) equilibrium density gradient ultracentrifugation and the large-scale purification of RNA nanoparticles by sucrose gradient rate-zonal ultracentrifugation or cushioned sucrose gradient rate-zonal ultracentrifugation.

  11. Learning networks for sustainable, large-scale improvement.

    PubMed

    McCannon, C Joseph; Perla, Rocco J

    2009-05-01

    Large-scale improvement efforts known as improvement networks offer structured opportunities for exchange of information and insights into the adaptation of clinical protocols to a variety of settings.

  12. Interpretation of plasma diagnostics package results in terms of large space structure plasma interactions

    NASA Technical Reports Server (NTRS)

    Kurth, William S.

    1991-01-01

    The Plasma Diagnostics Package (PDP) is a spacecraft which was designed and built at The University of Iowa and which contained several scientific instruments. These instruments were used for measuring Space Shuttle Orbiter environmental parameters and plasma parameters. The PDP flew on two Space Shuttle flights. The first flight of the PDP was on Space Shuttle Mission STS-3 and was a part of the NASA/Office of Space Science payload (OSS-1). The second flight of the PDP was on Space Shuttle Mission STS/51F and was a part of Spacelab 2. The interpretation of both the OSS-1 and Spacelab 2 PDP results in terms of large space structure plasma interactions is emphasized.

  13. A unified large/small-scale dynamo in helical turbulence

    NASA Astrophysics Data System (ADS)

    Bhat, Pallavi; Subramanian, Kandaswamy; Brandenburg, Axel

    2016-09-01

    We use high resolution direct numerical simulations (DNS) to show that helical turbulence can generate significant large-scale fields even in the presence of strong small-scale dynamo action. During the kinematic stage, the unified large/small-scale dynamo grows fields with a shape-invariant eigenfunction, with most power peaked at small scales or large k, as in Subramanian & Brandenburg. Nevertheless, the large-scale field can be clearly detected as an excess power at small k in the negatively polarized component of the energy spectrum for a forcing with positively polarized waves. Its strength overline{B}, relative to the total rms field Brms, decreases with increasing magnetic Reynolds number, ReM. However, as the Lorentz force becomes important, the field generated by the unified dynamo orders itself by saturating on successively larger scales. The magnetic integral scale for the positively polarized waves, characterizing the small-scale field, increases significantly from the kinematic stage to saturation. This implies that the small-scale field becomes as coherent as possible for a given forcing scale, which averts the ReM-dependent quenching of overline{B}/B_rms. These results are obtained for 10243 DNS with magnetic Prandtl numbers of PrM = 0.1 and 10. For PrM = 0.1, overline{B}/B_rms grows from about 0.04 to about 0.4 at saturation, aided in the final stages by helicity dissipation. For PrM = 10, overline{B}/B_rms grows from much less than 0.01 to values of the order the 0.2. Our results confirm that there is a unified large/small-scale dynamo in helical turbulence.

  14. Bayesian hierarchical model for large-scale covariance matrix estimation.

    PubMed

    Zhu, Dongxiao; Hero, Alfred O

    2007-12-01

    Many bioinformatics problems implicitly depend on estimating large-scale covariance matrix. The traditional approaches tend to give rise to high variance and low accuracy due to "overfitting." We cast the large-scale covariance matrix estimation problem into the Bayesian hierarchical model framework, and introduce dependency between covariance parameters. We demonstrate the advantages of our approaches over the traditional approaches using simulations and OMICS data analysis.

  15. Turbulent amplification of large-scale magnetic fields

    NASA Technical Reports Server (NTRS)

    Montgomery, D.; Chen, H.

    1984-01-01

    Previously-introduced methods for analytically estimating the effects of small-scale turbulent fluctuations on large-scale dynamics are extended to fully three-dimensional magnetohydrodynamics. The problem becomes algebraically tractable in the presence of sufficiently large spectral gaps. The calculation generalizes 'alpha dynamo' calculations, except that the velocity fluctuations and magnetic fluctuations are treated on an independent and equal footing. Earlier expressions for the 'alpha coefficients' of turbulent magnetic field amplification are recovered as a special case.

  16. A Cloud Computing Platform for Large-Scale Forensic Computing

    NASA Astrophysics Data System (ADS)

    Roussev, Vassil; Wang, Liqiang; Richard, Golden; Marziale, Lodovico

    The timely processing of massive digital forensic collections demands the use of large-scale distributed computing resources and the flexibility to customize the processing performed on the collections. This paper describes MPI MapReduce (MMR), an open implementation of the MapReduce processing model that outperforms traditional forensic computing techniques. MMR provides linear scaling for CPU-intensive processing and super-linear scaling for indexing-related workloads.

  17. Large-scale microwave anisotropy from gravitating seeds

    NASA Technical Reports Server (NTRS)

    Veeraraghavan, Shoba; Stebbins, Albert

    1992-01-01

    Topological defects could have seeded primordial inhomogeneities in cosmological matter. We examine the horizon-scale matter and geometry perturbations generated by such seeds in an expanding homogeneous and isotropic universe. Evolving particle horizons generally lead to perturbations around motionless seeds, even when there are compensating initial underdensities in the matter. We describe the pattern of the resulting large angular scale microwave anisotropy.

  18. Efficient On-Demand Operations in Large-Scale Infrastructures

    ERIC Educational Resources Information Center

    Ko, Steven Y.

    2009-01-01

    In large-scale distributed infrastructures such as clouds, Grids, peer-to-peer systems, and wide-area testbeds, users and administrators typically desire to perform "on-demand operations" that deal with the most up-to-date state of the infrastructure. However, the scale and dynamism present in the operating environment make it challenging to…

  19. Gas-filled targets for large scalelength plasma interaction experiments on Nova

    SciTech Connect

    Powers, L.V.; Berger, R.L.; Munro, D.H.

    1994-11-01

    Stimulated Brillouin backscatter from large scale length gas-filled targets has been measured on Nova. These targets were designed to approximate conditions in indirect drive ignition target designs in underdense plasma electron density (n{sub e}{approximately}10{sup 21}/cm{sup 3}), temperature (T{sub e}>3 keV), and gradient scale lengths (L{sub n}{approximately} mm, L{sub v}>6 mm) as well as calculated gain for stimulated Brillouin scattering (SBS). The targets used in these experiments were gas-filled balloons with polyimide walls (gasbags) and gas-filled hohlraums. Detailed characterization using x-ray imaging and x-ray and optical spectroscopy verifies that the calculated plasma conditions are achieved. Time-resolved SBS backscatter from these targets is <3% for conditions similar to ignition target designs.

  20. Recursive architecture for large-scale adaptive system

    NASA Astrophysics Data System (ADS)

    Hanahara, Kazuyuki; Sugiyama, Yoshihiko

    1994-09-01

    'Large scale' is one of major trends in the research and development of recent engineering, especially in the field of aerospace structural system. This term expresses the large scale of an artifact in general, however, it also implies the large number of the components which make up the artifact in usual. Considering a large scale system which is especially used in remote space or deep-sea, such a system should be adaptive as well as robust by itself, because its control as well as maintenance by human operators are not easy due to the remoteness. An approach to realizing this large scale, adaptive and robust system is to build the system as an assemblage of components which are respectively adaptive by themselves. In this case, the robustness of the system can be achieved by using a large number of such components and suitable adaptation as well as maintenance strategies. Such a system gathers many research's interest and their studies such as decentralized motion control, configurating algorithm and characteristics of structural elements are reported. In this article, a recursive architecture concept is developed and discussed towards the realization of large scale system which consists of a number of uniform adaptive components. We propose an adaptation strategy based on the architecture and its implementation by means of hierarchically connected processing units. The robustness and the restoration from degeneration of the processing unit are also discussed. Two- and three-dimensional adaptive truss structures are conceptually designed based on the recursive architecture.

  1. Theory of coherent electron-scale magnetic structures in space plasma turbulence

    NASA Astrophysics Data System (ADS)

    Jovanović, Dušan; Alexandrova, Olga; Maksimović, Milan

    2015-08-01

    Recent spacecraft observations in the solar wind and in the Earth’s magnetosheath indicate that the dissipation range of magnetic turbulence probably takes place at electron scales. Here, we derive nonlinear electron magnetohydrodynamic (EMHD) equations for warm plasma, i.e. with the ratio of thermodynamic and magnetic pressures, β ∼ 1. This model describes plasma turbulence under the solar wind and magnetosheath conditions on the electron spatial scales and with the characteristic frequency that does not exceed the electron gyrofrequency. We show that at electron scales and in the presence of a sufficiently large temperature anisotropy {T}{e\\perp }/{T}{e\\parallel }\\gt 1, there exist self-organized, coherent, nonlinear dipole vortex structures associated with obliquely propagating whistler waves. These can be visualized as pairs of counterstreaming helicoidal currents that produce both the compressional and torsional perturbations of the magnetic field. In contrast to the previously known long-range EMHD dipolar vortices in a cold plasma, this novel solution is an evanescent mode, strongly localized in space (with wave numbers {k}\\perp \\gg {k}\\parallel ). It can constitute a building block for the plasma turbulence at short scales and provide a possible scenario of turbulence dissipation at electron scales.

  2. Large-Scale Hybrid Motor Testing. Chapter 10

    NASA Technical Reports Server (NTRS)

    Story, George

    2006-01-01

    Hybrid rocket motors can be successfully demonstrated at a small scale virtually anywhere. There have been many suitcase sized portable test stands assembled for demonstration of hybrids. They show the safety of hybrid rockets to the audiences. These small show motors and small laboratory scale motors can give comparative burn rate data for development of different fuel/oxidizer combinations, however questions that are always asked when hybrids are mentioned for large scale applications are - how do they scale and has it been shown in a large motor? To answer those questions, large scale motor testing is required to verify the hybrid motor at its true size. The necessity to conduct large-scale hybrid rocket motor tests to validate the burn rate from the small motors to application size has been documented in several place^'^^.^. Comparison of small scale hybrid data to that of larger scale data indicates that the fuel burn rate goes down with increasing port size, even with the same oxidizer flux. This trend holds for conventional hybrid motors with forward oxidizer injection and HTPB based fuels. While the reason this is occurring would make a great paper or study or thesis, it is not thoroughly understood at this time. Potential causes include the fact that since hybrid combustion is boundary layer driven, the larger port sizes reduce the interaction (radiation, mixing and heat transfer) from the core region of the port. This chapter focuses on some of the large, prototype sized testing of hybrid motors. The largest motors tested have been AMROC s 250K-lbf thrust motor at Edwards Air Force Base and the Hybrid Propulsion Demonstration Program s 250K-lbf thrust motor at Stennis Space Center. Numerous smaller tests were performed to support the burn rate, stability and scaling concepts that went into the development of those large motors.

  3. Clearing and Labeling Techniques for Large-Scale Biological Tissues

    PubMed Central

    Seo, Jinyoung; Choe, Minjin; Kim, Sung-Yon

    2016-01-01

    Clearing and labeling techniques for large-scale biological tissues enable simultaneous extraction of molecular and structural information with minimal disassembly of the sample, facilitating the integration of molecular, cellular and systems biology across different scales. Recent years have witnessed an explosive increase in the number of such methods and their applications, reflecting heightened interest in organ-wide clearing and labeling across many fields of biology and medicine. In this review, we provide an overview and comparison of existing clearing and labeling techniques and discuss challenges and opportunities in the investigations of large-scale biological systems. PMID:27239813

  4. Scaling of Magnetic Reconnection in Relativistic Collisionless Pair Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, Yi-Hsin; Guo, Fan; Daughton, William; Li, Hui; Hesse, Michael

    2015-01-01

    Using fully kinetic simulations, we study the scaling of the inflow speed of collisionless magnetic reconnection in electron-positron plasmas from the non-relativistic to ultra-relativistic limit. In the anti-parallel configuration, the inflow speed increases with the upstream magnetization parameter sigma and approaches the speed of light when sigma is greater than O(100), leading to an enhanced reconnection rate. In all regimes, the divergence of the pressure tensor is the dominant term responsible for breaking the frozen-in condition at the x-line. The observed scaling agrees well with a simple model that accounts for the Lorentz contraction of the plasma passing through the diffusion region. The results demonstrate that the aspect ratio of the diffusion region, modified by the compression factor of proper density, remains approximately 0.1 in both the non-relativistic and relativistic limits.

  5. Lessons from Large-Scale Renewable Energy Integration Studies: Preprint

    SciTech Connect

    Bird, L.; Milligan, M.

    2012-06-01

    In general, large-scale integration studies in Europe and the United States find that high penetrations of renewable generation are technically feasible with operational changes and increased access to transmission. This paper describes other key findings such as the need for fast markets, large balancing areas, system flexibility, and the use of advanced forecasting.

  6. Large Scale Survey Data in Career Development Research

    ERIC Educational Resources Information Center

    Diemer, Matthew A.

    2008-01-01

    Large scale survey datasets have been underutilized but offer numerous advantages for career development scholars, as they contain numerous career development constructs with large and diverse samples that are followed longitudinally. Constructs such as work salience, vocational expectations, educational expectations, work satisfaction, and…

  7. A relativistic signature in large-scale structure

    NASA Astrophysics Data System (ADS)

    Bartolo, Nicola; Bertacca, Daniele; Bruni, Marco; Koyama, Kazuya; Maartens, Roy; Matarrese, Sabino; Sasaki, Misao; Verde, Licia; Wands, David

    2016-09-01

    In General Relativity, the constraint equation relating metric and density perturbations is inherently nonlinear, leading to an effective non-Gaussianity in the dark matter density field on large scales-even if the primordial metric perturbation is Gaussian. Intrinsic non-Gaussianity in the large-scale dark matter overdensity in GR is real and physical. However, the variance smoothed on a local physical scale is not correlated with the large-scale curvature perturbation, so that there is no relativistic signature in the galaxy bias when using the simplest model of bias. It is an open question whether the observable mass proxies such as luminosity or weak lensing correspond directly to the physical mass in the simple halo bias model. If not, there may be observables that encode this relativistic signature.

  8. Electrolyte and plasma enzyme analyses during large-volume liposuction.

    PubMed

    Lipschitz, Avron H; Kenkel, Jeffrey M; Luby, Maureen; Sorokin, Evan; Rohrich, Rod J; Brown, Spencer A

    2004-09-01

    Substantial fluid shifts occur during liposuction as wetting solution is infiltrated subcutaneously and fat is evacuated, causing potential electrolyte imbalances. In the porcine model for large-volume liposuction, plasma aspartate aminotransferase and alanine transaminase levels were elevated following liposuction. These results raised concerns for possible mechanical injury and/or lidocaine-induced hepatocellular toxicity in a clinical setting. The first objective of this human model study was to explore the effect of the liposuction procedure on electrolyte balance. The second objective was to determine whether elevated plasma aminotransferase levels were observed subsequent to large-volume liposuction. Five female volunteers underwent three-stage, ultrasound-assisted liposuction. Blood samples were collected perioperatively. Plasma levels of sodium, potassium, venous carbon dioxide, blood urea nitrogen, chloride, and creatinine were determined. Liver function analyte levels were measured, including albumin, total protein, aspartate aminotransferase, and alanine transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, and total bilirubin. To further define intracellular enzyme release, creatine kinase levels were measured. Mild hyponatremia was evident postoperatively (134 to 136 mmol/liter) in four patients. Hypokalemia was evident intraoperatively in all subjects (mean +/- SEM; 3.3 +/- 0.16 mmol/liter; range, 3.0 to 3.4 mmol/liter). Hypoalbuminemia and hypoproteinemia were observed throughout the study (baseline: 2.9 +/- 0.2 g/dl; range, 2.6 to 3.5 g/dl), decreasing to 10 to 40 percent 24 hours postoperatively (2.0 +/- 0.2 g/dl; range, 1.7 to 2.1 g/dl). Aspartate aminotransferase, alanine transaminase, and creatine kinase levels were significantly elevated after the procedure (190 +/- 47.1 U/liter, 50 +/- 7.7 U/liter, and 11,219 +/- 2556.7 U/liter, respectively) (p < 0.01). Release of antidiuretic hormone and even mildly hypotonic intravenous fluid

  9. Gyrokinetic simulation of isotope scaling in tokamak plasmas

    SciTech Connect

    Lee, W.W.; Santoro, R.A.

    1995-07-01

    A three-dimensional global gyrokinetic particle code in toroidal geometry has been used for investigating the transport properties of ion temperature gradient (ITG) drift instabilities in tokamak plasmas. Using the isotopes of hydrogen (H{sup +}), deuterium (D{sup +}) and tritium (T{sup +}), we have found that, under otherwise identical conditions, there exists a favorable isotope scaling for the ion thermal diffusivity, i.e., Xi decreases with mass. Such a scaling, which exists both at the saturation of the instability and also at the nonlinear steady state, can be understood from the resulting wavenumber and frequency spectra.

  10. Large-Scale Graph Processing Analysis using Supercomputer Cluster

    NASA Astrophysics Data System (ADS)

    Vildario, Alfrido; Fitriyani; Nugraha Nurkahfi, Galih

    2017-01-01

    Graph implementation is widely use in various sector such as automotive, traffic, image processing and many more. They produce graph in large-scale dimension, cause the processing need long computational time and high specification resources. This research addressed the analysis of implementation large-scale graph using supercomputer cluster. We impelemented graph processing by using Breadth-First Search (BFS) algorithm with single destination shortest path problem. Parallel BFS implementation with Message Passing Interface (MPI) used supercomputer cluster at High Performance Computing Laboratory Computational Science Telkom University and Stanford Large Network Dataset Collection. The result showed that the implementation give the speed up averages more than 30 times and eficiency almost 90%.

  11. Moon-based Earth Observation for Large Scale Geoscience Phenomena

    NASA Astrophysics Data System (ADS)

    Guo, Huadong; Liu, Guang; Ding, Yixing

    2016-07-01

    The capability of Earth observation for large-global-scale natural phenomena needs to be improved and new observing platform are expected. We have studied the concept of Moon as an Earth observation in these years. Comparing with manmade satellite platform, Moon-based Earth observation can obtain multi-spherical, full-band, active and passive information,which is of following advantages: large observation range, variable view angle, long-term continuous observation, extra-long life cycle, with the characteristics of longevity ,consistency, integrity, stability and uniqueness. Moon-based Earth observation is suitable for monitoring the large scale geoscience phenomena including large scale atmosphere change, large scale ocean change,large scale land surface dynamic change,solid earth dynamic change,etc. For the purpose of establishing a Moon-based Earth observation platform, we already have a plan to study the five aspects as follows: mechanism and models of moon-based observing earth sciences macroscopic phenomena; sensors' parameters optimization and methods of moon-based Earth observation; site selection and environment of moon-based Earth observation; Moon-based Earth observation platform; and Moon-based Earth observation fundamental scientific framework.

  12. Prototype Vector Machine for Large Scale Semi-Supervised Learning

    SciTech Connect

    Zhang, Kai; Kwok, James T.; Parvin, Bahram

    2009-04-29

    Practicaldataminingrarelyfalls exactlyinto the supervisedlearning scenario. Rather, the growing amount of unlabeled data poses a big challenge to large-scale semi-supervised learning (SSL). We note that the computationalintensivenessofgraph-based SSLarises largely from the manifold or graph regularization, which in turn lead to large models that are dificult to handle. To alleviate this, we proposed the prototype vector machine (PVM), a highlyscalable,graph-based algorithm for large-scale SSL. Our key innovation is the use of"prototypes vectors" for effcient approximation on both the graph-based regularizer and model representation. The choice of prototypes are grounded upon two important criteria: they not only perform effective low-rank approximation of the kernel matrix, but also span a model suffering the minimum information loss compared with the complete model. We demonstrate encouraging performance and appealing scaling properties of the PVM on a number of machine learning benchmark data sets.

  13. Acoustic Studies of the Large Scale Ocean Circulation

    NASA Technical Reports Server (NTRS)

    Menemenlis, Dimitris

    1999-01-01

    Detailed knowledge of ocean circulation and its transport properties is prerequisite to an understanding of the earth's climate and of important biological and chemical cycles. Results from two recent experiments, THETIS-2 in the Western Mediterranean and ATOC in the North Pacific, illustrate the use of ocean acoustic tomography for studies of the large scale circulation. The attraction of acoustic tomography is its ability to sample and average the large-scale oceanic thermal structure, synoptically, along several sections, and at regular intervals. In both studies, the acoustic data are compared to, and then combined with, general circulation models, meteorological analyses, satellite altimetry, and direct measurements from ships. Both studies provide complete regional descriptions of the time-evolving, three-dimensional, large scale circulation, albeit with large uncertainties. The studies raise serious issues about existing ocean observing capability and provide guidelines for future efforts.

  14. Toward Improved Support for Loosely Coupled Large Scale Simulation Workflows

    SciTech Connect

    Boehm, Swen; Elwasif, Wael R; Naughton, III, Thomas J; Vallee, Geoffroy R

    2014-01-01

    High-performance computing (HPC) workloads are increasingly leveraging loosely coupled large scale simula- tions. Unfortunately, most large-scale HPC platforms, including Cray/ALPS environments, are designed for the execution of long-running jobs based on coarse-grained launch capabilities (e.g., one MPI rank per core on all allocated compute nodes). This assumption limits capability-class workload campaigns that require large numbers of discrete or loosely coupled simulations, and where time-to-solution is an untenable pacing issue. This paper describes the challenges related to the support of fine-grained launch capabilities that are necessary for the execution of loosely coupled large scale simulations on Cray/ALPS platforms. More precisely, we present the details of an enhanced runtime system to support this use case, and report on initial results from early testing on systems at Oak Ridge National Laboratory.

  15. Measurement of high-frequency, small scale density fluctuations in improved confinement RFP plasmas

    NASA Astrophysics Data System (ADS)

    Duff, J. R.; Chapman, B. E.; Sarff, J. S.; Carmody, D.; Terry, P. W.; den Hartog, D. J.; Morton, L. A.; Lin, L.; Ding, W. X.; Brower, D. L.; MST Team

    2014-10-01

    In standard MST RFP plasmas, core transport is governed by magnetic fluctuations associated with global tearing modes. Using pulsed parallel current drive, tearing is significantly reduced and smaller-scale fluctuations are likely important to electron particle and heat transport for these improved confinement plasmas. On MST, an 11-chord FIR laser-based interferometry diagnostic, with ~ 8 cm chord spacing, is used to measure electron density fluctuations with wavenumbers k < 1-2 cm-1. An upgrade underway will allow resolution up to k ~ 15 cm-1. A fast magnetic coil array is employed for magnetic fluctuations. High-frequency (>50 kHz) small-scale (n > 15) density and magnetic fluctuations have been observed in the edge plasma, where density and temperature gradients are largest. These fluctuations are distinct from tearing and have amplitudes that correlate with the density gradient and electron beta. The MST is well suited to explore beta scaling given the large dynamic range (9-26%) found in the device. Correlation of the measured density fluctuations with plasma parameters in high beta plasmas will serve to identify the drive and contribute to validation of gyrokinetic codes. Work supported by DOE and NSF.

  16. Numerical methods for large-scale, time-dependent partial differential equations

    NASA Technical Reports Server (NTRS)

    Turkel, E.

    1979-01-01

    A survey of numerical methods for time dependent partial differential equations is presented. The emphasis is on practical applications to large scale problems. A discussion of new developments in high order methods and moving grids is given. The importance of boundary conditions is stressed for both internal and external flows. A description of implicit methods is presented including generalizations to multidimensions. Shocks, aerodynamics, meteorology, plasma physics and combustion applications are also briefly described.

  17. The effect of microscale random Alfven waves on the propagation of large-scale Alfven waves

    NASA Astrophysics Data System (ADS)

    Namikawa, T.; Hamabata, H.

    1983-04-01

    The ponderomotive force generated by random Alfven waves in a collisionless plasma is evaluated taking into account mean magnetic and velocity shear and is expressed as a series involving spatial derivatives of mean magnetic and velocity fields whose coefficients are associated with the helicity spectrum function of random velocity field. The effect of microscale random Alfven waves through ponderomotive and mean electromotive forces generated by them on the propagation of large-scale Alfven waves is also investigated.

  18. Large-scale silicon optical switches for optical interconnection

    NASA Astrophysics Data System (ADS)

    Qiao, Lei; Tang, Weijie; Chu, Tao

    2016-11-01

    Large-scale optical switches are greatly demanded in building optical interconnections in data centers and high performance computers (HPCs). Silicon optical switches have advantages of being compact and CMOS process compatible, which can be easily monolithically integrated. However, there are difficulties to construct large ports silicon optical switches. One of them is the non-uniformity of the switch units in large scale silicon optical switches, which arises from the fabrication error and causes confusion in finding the unit optimum operation points. In this paper, we proposed a method to detect the optimum operating point in large scale switch with limited build-in power monitors. We also propose methods for improving the unbalanced crosstalk of cross/bar states in silicon electro-optical MZI switches and insertion losses. Our recent progress in large scale silicon optical switches, including 64 × 64 thermal-optical and 32 × 32 electro-optical switches will be introduced. To the best our knowledge, both of them are the largest scale silicon optical switches in their sections, respectively. The switches were fabricated on 340-nm SOI substrates with CMOS 180- nm processes. The crosstalk of the 32 × 32 electro-optic switch was -19.2dB to -25.1 dB, while the value of the 64 × 64 thermal-optic switch was -30 dB to -48.3 dB.

  19. EINSTEIN'S SIGNATURE IN COSMOLOGICAL LARGE-SCALE STRUCTURE

    SciTech Connect

    Bruni, Marco; Hidalgo, Juan Carlos; Wands, David

    2014-10-10

    We show how the nonlinearity of general relativity generates a characteristic nonGaussian signal in cosmological large-scale structure that we calculate at all perturbative orders in a large-scale limit. Newtonian gravity and general relativity provide complementary theoretical frameworks for modeling large-scale structure in ΛCDM cosmology; a relativistic approach is essential to determine initial conditions, which can then be used in Newtonian simulations studying the nonlinear evolution of the matter density. Most inflationary models in the very early universe predict an almost Gaussian distribution for the primordial metric perturbation, ζ. However, we argue that it is the Ricci curvature of comoving-orthogonal spatial hypersurfaces, R, that drives structure formation at large scales. We show how the nonlinear relation between the spatial curvature, R, and the metric perturbation, ζ, translates into a specific nonGaussian contribution to the initial comoving matter density that we calculate for the simple case of an initially Gaussian ζ. Our analysis shows the nonlinear signature of Einstein's gravity in large-scale structure.

  20. The Phoenix series large scale LNG pool fire experiments.

    SciTech Connect

    Simpson, Richard B.; Jensen, Richard Pearson; Demosthenous, Byron; Luketa, Anay Josephine; Ricks, Allen Joseph; Hightower, Marion Michael; Blanchat, Thomas K.; Helmick, Paul H.; Tieszen, Sheldon Robert; Deola, Regina Anne; Mercier, Jeffrey Alan; Suo-Anttila, Jill Marie; Miller, Timothy J.

    2010-12-01

    The increasing demand for natural gas could increase the number and frequency of Liquefied Natural Gas (LNG) tanker deliveries to ports across the United States. Because of the increasing number of shipments and the number of possible new facilities, concerns about the potential safety of the public and property from an accidental, and even more importantly intentional spills, have increased. While improvements have been made over the past decade in assessing hazards from LNG spills, the existing experimental data is much smaller in size and scale than many postulated large accidental and intentional spills. Since the physics and hazards from a fire change with fire size, there are concerns about the adequacy of current hazard prediction techniques for large LNG spills and fires. To address these concerns, Congress funded the Department of Energy (DOE) in 2008 to conduct a series of laboratory and large-scale LNG pool fire experiments at Sandia National Laboratories (Sandia) in Albuquerque, New Mexico. This report presents the test data and results of both sets of fire experiments. A series of five reduced-scale (gas burner) tests (yielding 27 sets of data) were conducted in 2007 and 2008 at Sandia's Thermal Test Complex (TTC) to assess flame height to fire diameter ratios as a function of nondimensional heat release rates for extrapolation to large-scale LNG fires. The large-scale LNG pool fire experiments were conducted in a 120 m diameter pond specially designed and constructed in Sandia's Area III large-scale test complex. Two fire tests of LNG spills of 21 and 81 m in diameter were conducted in 2009 to improve the understanding of flame height, smoke production, and burn rate and therefore the physics and hazards of large LNG spills and fires.

  1. Measurement of the effects of large scale anisotropy on the small scales of turbulence

    NASA Astrophysics Data System (ADS)

    Wijesinghe, Susantha W. A.

    This thesis reports measurements of anisotropy in a laboratory turbulent flow generated by two oscillating grids. It has recently been identified that SO(3) decomposition of Eulerian structure functions provides a powerful tool for analyzing anisotropy in turbulence. From 3D particle tracks obtained with stereoscpic high speed video, we measure the longitudinal Eulerian structure functions for which SO(3) decomposition becomes a spherical harmonic decomposition. This method allows us to measure the anisotropy in different sectors, specified by j and m of the spherical harmonics Yjm (theta, φ). In order to acquire huge data sets required for the full 3D measurement of anisotropy as a function of scale, we have upgraded the optical tracking system to four high speed cameras with a new real-time image compression system. We achieved compression ratios of 154--614 depending on the number of particles appearing in an image. Anisotropy measurements are performed at three different detection volumes in the tank for two grid frequencies where Reynolds numbers vary from Relambda = 132 to Relambda = 277. Increasing j sectors show faster decay of anisotropy as scale decreases, consistent with the idea that the small scales should become isotropic at very high Reynolds number. Measured anisotropic scaling exponents are also consistent with previous studies performed with numerical simulations and hot wire anemometry. By conditioning the different j sectors on the instantaneous large scale velocity, we are able to quantify the dependence of the anisotropy on the state of the large scales. The isotropic sector shows a strong dependence on the state of the large scales. For the isotropic sector, this strong dependence is the same at all length scales showing that the small scales do not become independent of the large scales and confirms previous work by Blum et al. However, for a given state of the large scales, the anisotropic sector diminishes toward smaller length scales

  2. Dynamic properties of small-scale solar wind plasma fluctuations.

    PubMed

    Riazantseva, M O; Budaev, V P; Zelenyi, L M; Zastenker, G N; Pavlos, G P; Safrankova, J; Nemecek, Z; Prech, L; Nemec, F

    2015-05-13

    The paper presents the latest results of the studies of small-scale fluctuations in a turbulent flow of solar wind (SW) using measurements with extremely high temporal resolution (up to 0.03 s) of the bright monitor of SW (BMSW) plasma spectrometer operating on astrophysical SPECTR-R spacecraft at distances up to 350,000 km from the Earth. The spectra of SW ion flux fluctuations in the range of scales between 0.03 and 100 s are systematically analysed. The difference of slopes in low- and high-frequency parts of spectra and the frequency of the break point between these two characteristic slopes was analysed for different conditions in the SW. The statistical properties of the SW ion flux fluctuations were thoroughly analysed on scales less than 10 s. A high level of intermittency is demonstrated. The extended self-similarity of SW ion flux turbulent flow is constantly observed. The approximation of non-Gaussian probability distribution function of ion flux fluctuations by the Tsallis statistics shows the non-extensive character of SW fluctuations. Statistical characteristics of ion flux fluctuations are compared with the predictions of a log-Poisson model. The log-Poisson parametrization of the structure function scaling has shown that well-defined filament-like plasma structures are, as a rule, observed in the turbulent SW flows.

  3. High Density And High Temperature Plasmas In Large Helical Device

    NASA Astrophysics Data System (ADS)

    Komori, A.

    2010-07-01

    For the realization of the fusion reactor, it is necessary to confine high density and high temperature plasma for a time, which is well known as the Lawson criterion. To improve the plasma or confinement performance, vigorous experiments have been performed in the Large Helical Device (LHD) in National Institute for Fusion Science, which is the largest superconducting heliotron device with R = 3.9 m r = 0.6 m, Bt = 3 T. Recently a promising confinement regime called Super Dense Core (SDC) mode was discovered. An extremely high density core region with more than ~ 1 × 10^20 m-3 is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB (? = 0.6) is very high and the particle confinement in the core region is ~ 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. The IDB-SDC mode is also favorable from the engineering point of view since one can moderate demands for heating devices and plasma facing components. In order to achieve the IDB-SDC mode, the central fuelling with the pellet injection and the low recycling condition are essential. A repetitive pellet injector was newly developed to continuously feed the particle source to the central region. For the recycling control, the effective divertor system should be employed to control the edge plasma. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature more than 10 keV with the formation of the internal transport barrier (ITB). In the core region, the heat conductivity is improved to the neoclassical level, while no clear ITB for electron was seen. Another interesting phenomenon called "impurity hole" was observed inside the ITB. During the high ion temperature discharge, the im- purity density in the core region becomes

  4. Modulation analysis of large-scale discrete vortices.

    PubMed

    Cisneros, Luis A; Minzoni, Antonmaria A; Panayotaros, Panayotis; Smyth, Noel F

    2008-09-01

    The behavior of large-scale vortices governed by the discrete nonlinear Schrödinger equation is studied. Using a discrete version of modulation theory, it is shown how vortices are trapped and stabilized by the self-consistent Peierls-Nabarro potential that they generate in the lattice. Large-scale circular and polygonal vortices are studied away from the anticontinuum limit, which is the limit considered in previous studies. In addition numerical studies are performed on large-scale, straight structures, and it is found that they are stabilized by a nonconstant mean level produced by standing waves generated at the ends of the structure. Finally, numerical evidence is produced for long-lived, localized, quasiperiodic structures.

  5. Large-scale simulations of complex physical systems

    NASA Astrophysics Data System (ADS)

    Belić, A.

    2007-04-01

    Scientific computing has become a tool as vital as experimentation and theory for dealing with scientific challenges of the twenty-first century. Large scale simulations and modelling serve as heuristic tools in a broad problem-solving process. High-performance computing facilities make possible the first step in this process - a view of new and previously inaccessible domains in science and the building up of intuition regarding the new phenomenology. The final goal of this process is to translate this newly found intuition into better algorithms and new analytical results. In this presentation we give an outline of the research themes pursued at the Scientific Computing Laboratory of the Institute of Physics in Belgrade regarding large-scale simulations of complex classical and quantum physical systems, and present recent results obtained in the large-scale simulations of granular materials and path integrals.

  6. PKI security in large-scale healthcare networks.

    PubMed

    Mantas, Georgios; Lymberopoulos, Dimitrios; Komninos, Nikos

    2012-06-01

    During the past few years a lot of PKI (Public Key Infrastructures) infrastructures have been proposed for healthcare networks in order to ensure secure communication services and exchange of data among healthcare professionals. However, there is a plethora of challenges in these healthcare PKI infrastructures. Especially, there are a lot of challenges for PKI infrastructures deployed over large-scale healthcare networks. In this paper, we propose a PKI infrastructure to ensure security in a large-scale Internet-based healthcare network connecting a wide spectrum of healthcare units geographically distributed within a wide region. Furthermore, the proposed PKI infrastructure facilitates the trust issues that arise in a large-scale healthcare network including multi-domain PKI infrastructures.

  7. Space transportation booster engine thrust chamber technology, large scale injector

    NASA Technical Reports Server (NTRS)

    Schneider, J. A.

    1993-01-01

    The objective of the Large Scale Injector (LSI) program was to deliver a 21 inch diameter, 600,000 lbf thrust class injector to NASA/MSFC for hot fire testing. The hot fire test program would demonstrate the feasibility and integrity of the full scale injector, including combustion stability, chamber wall compatibility (thermal management), and injector performance. The 21 inch diameter injector was delivered in September of 1991.

  8. Scalable WIM: effective exploration in large-scale astrophysical environments.

    PubMed

    Li, Yinggang; Fu, Chi-Wing; Hanson, Andrew J

    2006-01-01

    Navigating through large-scale virtual environments such as simulations of the astrophysical Universe is difficult. The huge spatial range of astronomical models and the dominance of empty space make it hard for users to travel across cosmological scales effectively, and the problem of wayfinding further impedes the user's ability to acquire reliable spatial knowledge of astronomical contexts. We introduce a new technique called the scalable world-in-miniature (WIM) map as a unifying interface to facilitate travel and wayfinding in a virtual environment spanning gigantic spatial scales: Power-law spatial scaling enables rapid and accurate transitions among widely separated regions; logarithmically mapped miniature spaces offer a global overview mode when the full context is too large; 3D landmarks represented in the WIM are enhanced by scale, positional, and directional cues to augment spatial context awareness; a series of navigation models are incorporated into the scalable WIM to improve the performance of travel tasks posed by the unique characteristics of virtual cosmic exploration. The scalable WIM user interface supports an improved physical navigation experience and assists pragmatic cognitive understanding of a visualization context that incorporates the features of large-scale astronomy.

  9. Laser-plasma interactions in NIF-scale plasmas (HLP5 and HLP6)

    SciTech Connect

    MacGowan, B.; Berger, R.; Fernandez, J.

    1996-06-01

    The understanding of laser-plasma interactions in ignition-scale inertial confinement fusion (ICF) hohlraum targets is important for the success of the proposed National Ignition Facility (NIF). The success of an indirect-drive ICF ignition experiment depends on the ability to predict and control the history and spatial distribution of the x-radiation produced by the laser beams that are absorbed by the inside of the hohlraum wall. Only by controlling the symmetry of this x-ray drive is it possible to obtain the implosion symmetry in the fusion pellet necessary for ignition. The larger hohlraums and longer time scales required for ignition-scale targets result in the presence of several millimeters of plasma (electron density n{sub e} {approximately} 0.1 n{sub c} {approximately} 10{sup 21} cm{sup {minus}3}), through which the 3{omega} (351-nm) laser beams must propagate before they are absorbed at the hohlraum wall. Hydrodynamic simulations show this plasma to be very uniform [density-gradient scalelength L{sub n} = n{sub e}(dn{sub e}/dx){sup {minus}1}{approximately} 2mm] and to exhibit low velocity gradients [velocity-gradient scale-length L{sub v} = c{sub s}(dv/dx){sup {minus}1} > 6 mm].

  10. The Evolution of Baryons in Cosmic Large Scale Structure

    NASA Astrophysics Data System (ADS)

    Snedden, Ali; Arielle Phillips, Lara; Mathews, Grant James; Coughlin, Jared; Suh, In-Saeng; Bhattacharya, Aparna

    2015-01-01

    The environments of galaxies play a critical role in their formation and evolution. We study these environments using cosmological simulations with star formation and supernova feedback included. From these simulations, we parse the large scale structure into clusters, filaments and voids using a segmentation algorithm adapted from medical imaging. We trace the star formation history, gas phase and metal evolution of the baryons in the intergalactic medium as function of structure. We find that our algorithm reproduces the baryon fraction in the intracluster medium and that the majority of star formation occurs in cold, dense filaments. We present the consequences this large scale environment has for galactic halos and galaxy evolution.

  11. [Issues of large scale tissue culture of medicinal plant].

    PubMed

    Lv, Dong-Mei; Yuan, Yuan; Zhan, Zhi-Lai

    2014-09-01

    In order to increase the yield and quality of the medicinal plant and enhance the competitive power of industry of medicinal plant in our country, this paper analyzed the status, problem and countermeasure of the tissue culture of medicinal plant on large scale. Although the biotechnology is one of the most efficient and promising means in production of medicinal plant, it still has problems such as stability of the material, safety of the transgenic medicinal plant and optimization of cultured condition. Establishing perfect evaluation system according to the characteristic of the medicinal plant is the key measures to assure the sustainable development of the tissue culture of medicinal plant on large scale.

  12. Corridors Increase Plant Species Richness at Large Scales

    SciTech Connect

    Damschen, Ellen I.; Haddad, Nick M.; Orrock,John L.; Tewksbury, Joshua J.; Levey, Douglas J.

    2006-09-01

    Habitat fragmentation is one of the largest threats to biodiversity. Landscape corridors, which are hypothesized to reduce the negative consequences of fragmentation, have become common features of ecological management plans worldwide. Despite their popularity, there is little evidence documenting the effectiveness of corridors in preserving biodiversity at large scales. Using a large-scale replicated experiment, we showed that habitat patches connected by corridors retain more native plant species than do isolated patches, that this difference increases over time, and that corridors do not promote invasion by exotic species. Our results support the use of corridors in biodiversity conservation.

  13. Large-scale structure from wiggly cosmic strings

    NASA Astrophysics Data System (ADS)

    Vachaspati, Tanmay; Vilenkin, Alexander

    1991-08-01

    Recent simulations of the evolution of cosmic strings indicate the presence of small-scale structure on the strings. It is shown that wakes produced by such 'wiggly' cosmic strings can result in the efficient formation of large-scale structure and large streaming velocities in the universe without significantly affecting the microwave-background isotropy. It is also argued that the motion of strings will lead to the generation of a primordial magnetic field. The most promising version of this scenario appears to be the one in which the universe is dominated by light neutrinos.

  14. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    SciTech Connect

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 [times] 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V[sub x] ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V[sub x], the polarization of an incoming, linearly polarized, laser beam is rotated by 90[degree]. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 [times] 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches.

  15. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    SciTech Connect

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 {times} 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V{sub x} ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V{sub x}, the polarization of an incoming, linearly polarized, laser beam is rotated by 90{degree}. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 {times} 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches.

  16. Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet

    NASA Astrophysics Data System (ADS)

    Hamrin, M.; Norqvist, P.; Marghitu, O.; Vaivads, A.; Klecker, B.; Kistler, L. M.; Dandouras, I.

    2009-11-01

    In this article, and in a companion paper by Hamrin et al. (2009) [Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs) in Earth's plasma sheet. From more than 80 Cluster plasma sheet crossings (660 h data) at the altitude of about 15-20 RE in the summer and fall of 2001, we have identified 116 Concentrated Load Regions (CLRs) and 35 Concentrated Generator Regions (CGRs). By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have estimated typical values of the scale size and life time of the CLRs and the CGRs. We find that a majority of the observed ECRs are rather stationary in space, but varying in time. Assuming that the ECRs are cylindrically shaped and equal in size, we conclude that the typical scale size of the ECRs is 2 RE≲ΔSECR≲5 RE. The ECRs hence occupy a significant portion of the mid altitude plasma sheet. Moreover, the CLRs appear to be somewhat larger than the CGRs. The life time of the ECRs are of the order of 1-10 min, consistent with the large scale magnetotail MHD simulations of Birn and Hesse (2005). The life time of the CGRs is somewhat shorter than for the CLRs. On time scales of 1-10 min, we believe that ECRs rise and vanish in significant regions of the plasma sheet, possibly oscillating between load and generator character. It is probable that at least some of the observed ECRs oscillate energy back and forth in the plasma sheet instead of channeling it to the ionosphere.

  17. Resonant plankton patchiness induced by large-scale turbulent flow

    NASA Astrophysics Data System (ADS)

    McKiver, William J.; Neufeld, Zoltán

    2011-01-01

    Here we study how large-scale variability of oceanic plankton is affected by mesoscale turbulence in a spatially heterogeneous environment. We consider a phytoplankton-zooplankton (PZ) ecosystem model, with different types of zooplankton grazing functions, coupled to a turbulent flow described by the two-dimensional Navier-Stokes equations, representing large-scale horizontal transport in the ocean. We characterize the system using a dimensionless parameter, γ=TB/TF, which is the ratio of the ecosystem biological time scale TB and the flow time scale TF. Through numerical simulations, we examine how the PZ system depends on the time-scale ratio γ and find that the variance of both species changes significantly, with maximum phytoplankton variability at intermediate mixing rates. Through an analysis of the linearized population dynamics, we find an analytical solution based on the forced harmonic oscillator, which explains the behavior of the ecosystem, where there is resonance between the advection and the ecosystem predator-prey dynamics when the forcing time scales match the ecosystem time scales. We also examine the dependence of the power spectra on γ and find that the resonance behavior leads to different spectral slopes for phytoplankton and zooplankton, in agreement with observations.

  18. Resonant plankton patchiness induced by large-scale turbulent flow.

    PubMed

    McKiver, William J; Neufeld, Zoltán

    2011-01-01

    Here we study how large-scale variability of oceanic plankton is affected by mesoscale turbulence in a spatially heterogeneous environment. We consider a phytoplankton-zooplankton (PZ) ecosystem model, with different types of zooplankton grazing functions, coupled to a turbulent flow described by the two-dimensional Navier-Stokes equations, representing large-scale horizontal transport in the ocean. We characterize the system using a dimensionless parameter, γ=T(B)/T(F), which is the ratio of the ecosystem biological time scale T(B) and the flow time scale T(F). Through numerical simulations, we examine how the PZ system depends on the time-scale ratio γ and find that the variance of both species changes significantly, with maximum phytoplankton variability at intermediate mixing rates. Through an analysis of the linearized population dynamics, we find an analytical solution based on the forced harmonic oscillator, which explains the behavior of the ecosystem, where there is resonance between the advection and the ecosystem predator-prey dynamics when the forcing time scales match the ecosystem time scales. We also examine the dependence of the power spectra on γ and find that the resonance behavior leads to different spectral slopes for phytoplankton and zooplankton, in agreement with observations.

  19. Large-scale anisotropy in stably stratified rotating flows

    SciTech Connect

    Marino, R.; Mininni, P. D.; Rosenberg, D. L.; Pouquet, A.

    2014-08-28

    We present results from direct numerical simulations of the Boussinesq equations in the presence of rotation and/or stratification, both in the vertical direction. The runs are forced isotropically and randomly at small scales and have spatial resolutions of up to $1024^3$ grid points and Reynolds numbers of $\\approx 1000$. We first show that solutions with negative energy flux and inverse cascades develop in rotating turbulence, whether or not stratification is present. However, the purely stratified case is characterized instead by an early-time, highly anisotropic transfer to large scales with almost zero net isotropic energy flux. This is consistent with previous studies that observed the development of vertically sheared horizontal winds, although only at substantially later times. However, and unlike previous works, when sufficient scale separation is allowed between the forcing scale and the domain size, the total energy displays a perpendicular (horizontal) spectrum with power law behavior compatible with $\\sim k_\\perp^{-5/3}$, including in the absence of rotation. In this latter purely stratified case, such a spectrum is the result of a direct cascade of the energy contained in the large-scale horizontal wind, as is evidenced by a strong positive flux of energy in the parallel direction at all scales including the largest resolved scales.

  20. Large-scale anisotropy in stably stratified rotating flows

    DOE PAGES

    Marino, R.; Mininni, P. D.; Rosenberg, D. L.; ...

    2014-08-28

    We present results from direct numerical simulations of the Boussinesq equations in the presence of rotation and/or stratification, both in the vertical direction. The runs are forced isotropically and randomly at small scales and have spatial resolutions of up tomore » $1024^3$ grid points and Reynolds numbers of $$\\approx 1000$$. We first show that solutions with negative energy flux and inverse cascades develop in rotating turbulence, whether or not stratification is present. However, the purely stratified case is characterized instead by an early-time, highly anisotropic transfer to large scales with almost zero net isotropic energy flux. This is consistent with previous studies that observed the development of vertically sheared horizontal winds, although only at substantially later times. However, and unlike previous works, when sufficient scale separation is allowed between the forcing scale and the domain size, the total energy displays a perpendicular (horizontal) spectrum with power law behavior compatible with $$\\sim k_\\perp^{-5/3}$$, including in the absence of rotation. In this latter purely stratified case, such a spectrum is the result of a direct cascade of the energy contained in the large-scale horizontal wind, as is evidenced by a strong positive flux of energy in the parallel direction at all scales including the largest resolved scales.« less

  1. Laser-Plasma Interactions in NIF Direct-Drive-Scale Plasmas

    NASA Astrophysics Data System (ADS)

    Regan, S. P.

    1998-11-01

    Laser-plasma interactions have been carried out on OMEGA under plasma conditions representative of the peak of the NIF direct-drive laser pulse. This pulse, for a 1.5 MJ, α = 3 design, has a peak intensity of 2 × 10^15 W/cm^2 (summed over all beams) and a foot intensity of 4 × 10^13 W/cm^2. The coronal plasmas predicted for these implosions have Te ~ 4 keV and a ~1-mm density scale length at the peak of the laser pulse, and Te ~ 600 eV and a ~0.25-mm density scale length during the foot. In the OMEGA experiments, exploding foil plasmas with a maximum on-axis density of n_c/5 have been produced by irradiating mass-limited, 18- to 20-μm-thick CH foils on both sides with a total of 20 kJ of laser energy from 38 beams. In addition, NIF direct-drive scale plasmas including a critical density have been created by irradiating solid CH targets on one side with 10 kJ of laser energy from 19 beams. All of the experiments were carried out with distributed phase plates (DPP's) and 2-D SSD ( ~0.25 THz). The electron temperature and density of exploding-foil plasmas have been diagnosed using time-resolved x-ray spectroscopy and stimulated Raman scattering (SRS) measurements and are consistent with SAGE code predictions. Temperatures increasing with time up to 4 keV have been found. When these plasmas were irradiated with our interaction beam at ~1.5 × 10^15 W/cm^2, stimulated Brillouin backscattering (SBS) was found to be completely inhibited when DPP's were used. Without a DPP in the interaction beam, the SBS reflectivity can exceed 10%. Future experiments on OMEGA will address the parametric instabilities of the coronal plasmas in the foot and transition regions of the NIF laser pulse. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460. *In collaboration with D.K. Bradley^a, J.J. Carroll III^b, A.V. Chirokikh^a, R.S. Craxton^a, R.P. Drake^b, D.D. Meyerhofer^a, W. Seka^a, R

  2. New probes of Cosmic Microwave Background large-scale anomalies

    NASA Astrophysics Data System (ADS)

    Aiola, Simone

    Fifty years of Cosmic Microwave Background (CMB) data played a crucial role in constraining the parameters of the LambdaCDM model, where Dark Energy, Dark Matter, and Inflation are the three most important pillars not yet understood. Inflation prescribes an isotropic universe on large scales, and it generates spatially-correlated density fluctuations over the whole Hubble volume. CMB temperature fluctuations on scales bigger than a degree in the sky, affected by modes on super-horizon scale at the time of recombination, are a clean snapshot of the universe after inflation. In addition, the accelerated expansion of the universe, driven by Dark Energy, leaves a hardly detectable imprint in the large-scale temperature sky at late times. Such fundamental predictions have been tested with current CMB data and found to be in tension with what we expect from our simple LambdaCDM model. Is this tension just a random fluke or a fundamental issue with the present model? In this thesis, we present a new framework to probe the lack of large-scale correlations in the temperature sky using CMB polarization data. Our analysis shows that if a suppression in the CMB polarization correlations is detected, it will provide compelling evidence for new physics on super-horizon scale. To further analyze the statistical properties of the CMB temperature sky, we constrain the degree of statistical anisotropy of the CMB in the context of the observed large-scale dipole power asymmetry. We find evidence for a scale-dependent dipolar modulation at 2.5sigma. To isolate late-time signals from the primordial ones, we test the anomalously high Integrated Sachs-Wolfe effect signal generated by superstructures in the universe. We find that the detected signal is in tension with the expectations from LambdaCDM at the 2.5sigma level, which is somewhat smaller than what has been previously argued. To conclude, we describe the current status of CMB observations on small scales, highlighting the

  3. Local and Regional Impacts of Large Scale Wind Energy Deployment

    NASA Astrophysics Data System (ADS)

    Michalakes, J.; Hammond, S.; Lundquist, J. K.; Moriarty, P.; Robinson, M.

    2010-12-01

    The U.S. is currently on a path to produce 20% of its electricity from wind energy by 2030, almost a 10-fold increase over present levels of electricity generated from wind. Such high-penetration wind energy deployment will entail extracting elevated energy levels from the planetary boundary layer and preliminary studies indicate that this will have significant but uncertain impacts on the local and regional environment. State and federal regulators have raised serious concerns regarding potential agricultural impacts from large farms deployed throughout the Midwest where agriculture is the basis of the local economy. The effects of large wind farms have been proposed to be both beneficial (drying crops to reduce occurrences of fungal diseases, avoiding late spring freezes, enhancing pollen viability, reducing dew duration) and detrimental (accelerating moisture loss during drought) with no conclusive investigations thus far. As both wind and solar technologies are deployed at scales required to replace conventional technologies, there must be reasonable certainty that the potential environmental impacts at the micro, macro, regional and global scale do not exceed those anticipated from carbon emissions. Largely because of computational limits, the role of large wind farms in affecting regional-scale weather patterns has only been investigated in coarse simulations and modeling tools do not yet exist which are capable of assessing the downwind affects of large wind farms may have on microclimatology. In this presentation, we will outline the vision for and discuss technical and scientific challenges in developing a multi-model high-performance simulation capability covering the range of mesoscale to sub-millimeter scales appropriate for assessing local, regional, and ultimately global environmental impacts and quantifying uncertainties of large scale wind energy deployment scenarios. Such a system will allow continuous downscaling of atmospheric processes on wind

  4. Large-scale smart passive system for civil engineering applications

    NASA Astrophysics Data System (ADS)

    Jung, Hyung-Jo; Jang, Dong-Doo; Lee, Heon-Jae; Cho, Sang-Won

    2008-03-01

    The smart passive system consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) part has been recently proposed. An EMI part can generate the input current for an MR damper from vibration of a structure according to Faraday's law of electromagnetic induction. The control performance of the smart passive system has been demonstrated mainly by numerical simulations. It was verified from the numerical results that the system could be effective to reduce the structural responses in the cases of civil engineering structures such as buildings and bridges. On the other hand, the experimental validation of the system is not sufficiently conducted yet. In this paper, the feasibility of the smart passive system to real-scale structures is investigated. To do this, the large-scale smart passive system is designed, manufactured, and tested. The system consists of the large-capacity MR damper, which has a maximum force level of approximately +/-10,000N, a maximum stroke level of +/-35mm and the maximum current level of 3 A, and the large-scale EMI part, which is designed to generate sufficient induced current for the damper. The applicability of the smart passive system to large real-scale structures is examined through a series of shaking table tests. The magnitudes of the induced current of the EMI part with various sinusoidal excitation inputs are measured. According to the test results, the large-scale EMI part shows the possibility that it could generate the sufficient current or power for changing the damping characteristics of the large-capacity MR damper.

  5. Homogenization of Large-Scale Movement Models in Ecology

    USGS Publications Warehouse

    Garlick, M.J.; Powell, J.A.; Hooten, M.B.; McFarlane, L.R.

    2011-01-01

    A difficulty in using diffusion models to predict large scale animal population dispersal is that individuals move differently based on local information (as opposed to gradients) in differing habitat types. This can be accommodated by using ecological diffusion. However, real environments are often spatially complex, limiting application of a direct approach. Homogenization for partial differential equations has long been applied to Fickian diffusion (in which average individual movement is organized along gradients of habitat and population density). We derive a homogenization procedure for ecological diffusion and apply it to a simple model for chronic wasting disease in mule deer. Homogenization allows us to determine the impact of small scale (10-100 m) habitat variability on large scale (10-100 km) movement. The procedure generates asymptotic equations for solutions on the large scale with parameters defined by small-scale variation. The simplicity of this homogenization procedure is striking when compared to the multi-dimensional homogenization procedure for Fickian diffusion,and the method will be equally straightforward for more complex models. ?? 2010 Society for Mathematical Biology.

  6. The effective field theory of cosmological large scale structures

    SciTech Connect

    Carrasco, John Joseph M.; Hertzberg, Mark P.; Senatore, Leonardo

    2012-09-20

    Large scale structure surveys will likely become the next leading cosmological probe. In our universe, matter perturbations are large on short distances and small at long scales, i.e. strongly coupled in the UV and weakly coupled in the IR. To make precise analytical predictions on large scales, we develop an effective field theory formulated in terms of an IR effective fluid characterized by several parameters, such as speed of sound and viscosity. These parameters, determined by the UV physics described by the Boltzmann equation, are measured from N-body simulations. We find that the speed of sound of the effective fluid is c2s ≈ 10–6c2 and that the viscosity contributions are of the same order. The fluid describes all the relevant physics at long scales k and permits a manifestly convergent perturbative expansion in the size of the matter perturbations δ(k) for all the observables. As an example, we calculate the correction to the power spectrum at order δ(k)4. As a result, the predictions of the effective field theory are found to be in much better agreement with observation than standard cosmological perturbation theory, already reaching percent precision at this order up to a relatively short scale k ≃ 0.24h Mpc–1.

  7. Large eddy simulation of the atmosphere on various scales.

    PubMed

    Cullen, M J P; Brown, A R

    2009-07-28

    Numerical simulations of the atmosphere are routinely carried out on various scales for purposes ranging from weather forecasts for local areas a few hours ahead to forecasts of climate change over periods of hundreds of years. Almost without exception, these forecasts are made with space/time-averaged versions of the governing Navier-Stokes equations and laws of thermodynamics, together with additional terms representing internal and boundary forcing. The calculations are a form of large eddy modelling, because the subgrid-scale processes have to be modelled. In the global atmospheric models used for long-term predictions, the primary method is implicit large eddy modelling, using discretization to perform the averaging, supplemented by specialized subgrid models, where there is organized small-scale activity, such as in the lower boundary layer and near active convection. Smaller scale models used for local or short-range forecasts can use a much smaller averaging scale. This allows some of the specialized subgrid models to be dropped in favour of direct simulations. In research mode, the same models can be run as a conventional large eddy simulation only a few orders of magnitude away from a direct simulation. These simulations can then be used in the development of the subgrid models for coarser resolution models.

  8. Energy transfers in large-scale and small-scale dynamos

    NASA Astrophysics Data System (ADS)

    Samtaney, Ravi; Kumar, Rohit; Verma, Mahendra

    2015-11-01

    We present the energy transfers, mainly energy fluxes and shell-to-shell energy transfers in small-scale dynamo (SSD) and large-scale dynamo (LSD) using numerical simulations of MHD turbulence for Pm = 20 (SSD) and for Pm = 0.2 on 10243 grid. For SSD, we demonstrate that the magnetic energy growth is caused by nonlocal energy transfers from the large-scale or forcing-scale velocity field to small-scale magnetic field. The peak of these energy transfers move towards lower wavenumbers as dynamo evolves, which is the reason for the growth of the magnetic fields at the large scales. The energy transfers U2U (velocity to velocity) and B2B (magnetic to magnetic) are forward and local. For LSD, we show that the magnetic energy growth takes place via energy transfers from large-scale velocity field to large-scale magnetic field. We observe forward U2U and B2B energy flux, similar to SSD.

  9. Research on 2x1 plasma electrode electro-optical switch with large aperture

    NASA Astrophysics Data System (ADS)

    Zhang, Xiong Jun; Zheng, Kui Xing; Feng, B.; Wu, D. S.; Lu, J. P.; Tian, X. L.; Jin, F.; Sui, Zhan; Wei, Xiaofeng; Zhang, Xiaomin

    2005-01-01

    In conceptual design of the prototype for SG-III facility, a full aperture electro-optical switch was placed between the cavity mirror and the main amplifier to isolate the reflected beams. The beam on the cavity mirror is 240mm×240mm square. Pockells cells of conversional design with coaxial ring electrodes can not scale to such large square aperture. In the 1980s, a plasma electrode Pockels cell (PEPC) concept was invented at LLNL. It uses transparent plasma electrode formed through gas discharge as the electrodes to apply the voltage across switching crystal to rotate the polarization of a transmitted laser beam. And it can be scaled to large aperture with thin crystal. So the switch which would be used in SG-III is based on this technology. The technical integration line as a prototype of SG-III laser is actually a 4×2 beam bundle. And the full aperture optical switch is mechanically designed four apertures as a removable unit, and electrically two 2×1 PEPC putting together. So we built a 2×1 PEPC to develop the technology first. The 2×1 PEPC is a sandwich structure made of an insulating mid plane between a pair of plasma chambers. The frame of both plasma chambers are machining in duralumin. Each chamber is installed with a planar magnetic cathode and four segments spherical anodes made from stainless steel. The cathode and anode are insulated from the housing with a special shell made from plastic, and plasma is insulated from the housing by an 80-μm-thick anodic coating on the duralumin. The two plasma chambers are separated by a mid plane of glass frame with two square holes. The two holes are filled by two electro-optical crystals with a 240-mm square aperture. With the optimized operating pressure and the electrical parameters, a very good homogeneity and low resistivity plasma electrode is obtained. Finally we tested its switching performance to simulate the case that it will be used in the SG-III prototype facility. It works with a quarter wave

  10. Large-scale search for dark-matter axions

    SciTech Connect

    Kinion, D; van Bibber, K

    2000-08-30

    We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a ''second-generation'' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.

  11. Measurement, Sampling, and Equating Errors in Large-Scale Assessments

    ERIC Educational Resources Information Center

    Wu, Margaret

    2010-01-01

    In large-scale assessments, such as state-wide testing programs, national sample-based assessments, and international comparative studies, there are many steps involved in the measurement and reporting of student achievement. There are always sources of inaccuracies in each of the steps. It is of interest to identify the source and magnitude of…

  12. Resilience of Florida Keys coral communities following large scale disturbances

    EPA Science Inventory

    The decline of coral reefs in the Caribbean over the last 40 years has been attributed to multiple chronic stressors and episodic large-scale disturbances. This study assessed the resilience of coral communities in two different regions of the Florida Keys reef system between 199...

  13. Large-Scale Machine Learning for Classification and Search

    ERIC Educational Resources Information Center

    Liu, Wei

    2012-01-01

    With the rapid development of the Internet, nowadays tremendous amounts of data including images and videos, up to millions or billions, can be collected for training machine learning models. Inspired by this trend, this thesis is dedicated to developing large-scale machine learning techniques for the purpose of making classification and nearest…

  14. The Cosmology Large Angular Scale Surveyor (CLASS) Telescope Architecture

    NASA Technical Reports Server (NTRS)

    Chuss, David T.; Ali, Aamir; Amiri, Mandana; Appel, John W.; Araujo, Derek; Bennett, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Colazo, Felipe; Crowe, Erik; Denis, Kevin L.; Dunner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Gothe, Dominik; Halpern, Mark; Harrington, Kathleen; Hilton, Gene; Hinshaw, Gary F.; Huang, Caroline; Irwin, Kent; Jones, Glenn; Karakla, John; Kogut, Alan J.; Larson, David; Limon, Michele; Lowry, Lindsay; Marriage, Tobias; Mehrle, Nicholas; Stevenson, Thomas; Miller, Nathan J.; Moseley, Samuel H.; U-Yen, Kongpop; Wollack, Edward

    2014-01-01

    We describe the instrument architecture of the Johns Hopkins University-led CLASS instrument, a groundbased cosmic microwave background (CMB) polarimeter that will measure the large-scale polarization of the CMB in several frequency bands to search for evidence of inflation.

  15. Assuring Quality in Large-Scale Online Course Development

    ERIC Educational Resources Information Center

    Parscal, Tina; Riemer, Deborah

    2010-01-01

    Student demand for online education requires colleges and universities to rapidly expand the number of courses and programs offered online while maintaining high quality. This paper outlines two universities respective processes to assure quality in large-scale online programs that integrate instructional design, eBook custom publishing, Quality…

  16. Sparse approximation through boosting for learning large scale kernel machines.

    PubMed

    Sun, Ping; Yao, Xin

    2010-06-01

    Recently, sparse approximation has become a preferred method for learning large scale kernel machines. This technique attempts to represent the solution with only a subset of original data points also known as basis vectors, which are usually chosen one by one with a forward selection procedure based on some selection criteria. The computational complexity of several resultant algorithms scales as O(NM(2)) in time and O(NM) in memory, where N is the number of training points and M is the number of basis vectors as well as the steps of forward selection. For some large scale data sets, to obtain a better solution, we are sometimes required to include more basis vectors, which means that M is not trivial in this situation. However, the limited computational resource (e.g., memory) prevents us from including too many vectors. To handle this dilemma, we propose to add an ensemble of basis vectors instead of only one at each forward step. The proposed method, closely related to gradient boosting, could decrease the required number M of forward steps significantly and thus a large fraction of computational cost is saved. Numerical experiments on three large scale regression tasks and a classification problem demonstrate the effectiveness of the proposed approach.

  17. Large-Scale Assessments and Educational Policies in Italy

    ERIC Educational Resources Information Center

    Damiani, Valeria

    2016-01-01

    Despite Italy's extensive participation in most large-scale assessments, their actual influence on Italian educational policies is less easy to identify. The present contribution aims at highlighting and explaining reasons for the weak and often inconsistent relationship between international surveys and policy-making processes in Italy.…

  18. Improving the Utility of Large-Scale Assessments in Canada

    ERIC Educational Resources Information Center

    Rogers, W. Todd

    2014-01-01

    Principals and teachers do not use large-scale assessment results because the lack of distinct and reliable subtests prevents identifying strengths and weaknesses of students and instruction, the results arrive too late to be used, and principals and teachers need assistance to use the results to improve instruction so as to improve student…

  19. Large-Scale Innovation and Change in UK Higher Education

    ERIC Educational Resources Information Center

    Brown, Stephen

    2013-01-01

    This paper reflects on challenges universities face as they respond to change. It reviews current theories and models of change management, discusses why universities are particularly difficult environments in which to achieve large scale, lasting change and reports on a recent attempt by the UK JISC to enable a range of UK universities to employ…

  20. Mixing Metaphors: Building Infrastructure for Large Scale School Turnaround

    ERIC Educational Resources Information Center

    Peurach, Donald J.; Neumerski, Christine M.

    2015-01-01

    The purpose of this analysis is to increase understanding of the possibilities and challenges of building educational infrastructure--the basic, foundational structures, systems, and resources--to support large-scale school turnaround. Building educational infrastructure often exceeds the capacity of schools, districts, and state education…

  1. Large-Scale Environmental Influences on Aquatic Animal Health

    EPA Science Inventory

    In the latter portion of the 20th century, North America experienced numerous large-scale mortality events affecting a broad diversity of aquatic animals. Short-term forensic investigations of these events have sometimes characterized a causative agent or condition, but have rare...

  2. Probabilistic Cuing in Large-Scale Environmental Search

    ERIC Educational Resources Information Center

    Smith, Alastair D.; Hood, Bruce M.; Gilchrist, Iain D.

    2010-01-01

    Finding an object in our environment is an important human ability that also represents a critical component of human foraging behavior. One type of information that aids efficient large-scale search is the likelihood of the object being in one location over another. In this study we investigated the conditions under which individuals respond to…

  3. Newton Methods for Large Scale Problems in Machine Learning

    ERIC Educational Resources Information Center

    Hansen, Samantha Leigh

    2014-01-01

    The focus of this thesis is on practical ways of designing optimization algorithms for minimizing large-scale nonlinear functions with applications in machine learning. Chapter 1 introduces the overarching ideas in the thesis. Chapters 2 and 3 are geared towards supervised machine learning applications that involve minimizing a sum of loss…

  4. Large-Scale Physical Separation of Depleted Uranium from Soil

    DTIC Science & Technology

    2012-09-01

    ER D C/ EL T R -1 2 - 2 5 Army Range Technology Program Large-Scale Physical Separation of Depleted Uranium from Soil E nv ir on m en ta l...Separation ................................................................................................................ 2   Project Background...5  2   Materials and Methods

  5. Computational Complexity, Efficiency and Accountability in Large Scale Teleprocessing Systems.

    DTIC Science & Technology

    1980-12-01

    COMPLEXITY, EFFICIENCY AND ACCOUNTABILITY IN LARGE SCALE TELEPROCESSING SYSTEMS DAAG29-78-C-0036 STANFORD UNIVERSITY JOHN T. GILL MARTIN E. BELLMAN...solve but easy to check. Ve have also suggested howy sucb random tapes can be simulated by determin- istically generating "pseudorandom" numbers by a

  6. The large scale microwave background anisotropy in decaying particle cosmology

    SciTech Connect

    Panek, M.

    1987-06-01

    We investigate the large-scale anisotropy of the microwave background radiation in cosmological models with decaying particles. The observed value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z/sub d/ < 3-5. 12 refs., 2 figs.

  7. DESIGN OF LARGE-SCALE AIR MONITORING NETWORKS

    EPA Science Inventory

    The potential effects of air pollution on human health have received much attention in recent years. In the U.S. and other countries, there are extensive large-scale monitoring networks designed to collect data to inform the public of exposure risks to air pollution. A major crit...

  8. The Large-Scale Structure of Scientific Method

    ERIC Educational Resources Information Center

    Kosso, Peter

    2009-01-01

    The standard textbook description of the nature of science describes the proposal, testing, and acceptance of a theoretical idea almost entirely in isolation from other theories. The resulting model of science is a kind of piecemeal empiricism that misses the important network structure of scientific knowledge. Only the large-scale description of…

  9. Ecosystem resilience despite large-scale altered hydro climatic conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological paradigm for many regions. Large-scale, warm droughts have recently impacted North America, Africa, Europe, Amazonia, and Australia result...

  10. US National Large-scale City Orthoimage Standard Initiative

    USGS Publications Warehouse

    Zhou, G.; Song, C.; Benjamin, S.; Schickler, W.

    2003-01-01

    The early procedures and algorithms for National digital orthophoto generation in National Digital Orthophoto Program (NDOP) were based on earlier USGS mapping operations, such as field control, aerotriangulation (derived in the early 1920's), the quarter-quadrangle-centered (3.75 minutes of longitude and latitude in geographic extent), 1:40,000 aerial photographs, and 2.5 D digital elevation models. However, large-scale city orthophotos using early procedures have disclosed many shortcomings, e.g., ghost image, occlusion, shadow. Thus, to provide the technical base (algorithms, procedure) and experience needed for city large-scale digital orthophoto creation is essential for the near future national large-scale digital orthophoto deployment and the revision of the Standards for National Large-scale City Digital Orthophoto in National Digital Orthophoto Program (NDOP). This paper will report our initial research results as follows: (1) High-precision 3D city DSM generation through LIDAR data processing, (2) Spatial objects/features extraction through surface material information and high-accuracy 3D DSM data, (3) 3D city model development, (4) Algorithm development for generation of DTM-based orthophoto, and DBM-based orthophoto, (5) True orthophoto generation by merging DBM-based orthophoto and DTM-based orthophoto, and (6) Automatic mosaic by optimizing and combining imagery from many perspectives.

  11. Developing and Understanding Methods for Large-Scale Nonlinear Optimization

    DTIC Science & Technology

    2006-07-24

    algorithms for large-scale uncon- strained and constrained optimization problems, including limited-memory methods for problems with -2- many thousands...34Published in peer-reviewed journals" E. Eskow, B. Bader, R. Byrd, S. Crivelli, T. Head-Gordon, V. Lamberti and R. Schnabel, "An optimization approach to the

  12. International Large-Scale Assessments: What Uses, What Consequences?

    ERIC Educational Resources Information Center

    Johansson, Stefan

    2016-01-01

    Background: International large-scale assessments (ILSAs) are a much-debated phenomenon in education. Increasingly, their outcomes attract considerable media attention and influence educational policies in many jurisdictions worldwide. The relevance, uses and consequences of these assessments are often the focus of research scrutiny. Whilst some…

  13. Extracting Useful Semantic Information from Large Scale Corpora of Text

    ERIC Educational Resources Information Center

    Mendoza, Ray Padilla, Jr.

    2012-01-01

    Extracting and representing semantic information from large scale corpora is at the crux of computer-assisted knowledge generation. Semantic information depends on collocation extraction methods, mathematical models used to represent distributional information, and weighting functions which transform the space. This dissertation provides a…

  14. Large scale structure of the sun's radio corona

    NASA Technical Reports Server (NTRS)

    Kundu, M. R.

    1986-01-01

    Results of studies of large scale structures of the corona at long radio wavelengths are presented, using data obtained with the multifrequency radioheliograph of the Clark Lake Radio Observatory. It is shown that features corresponding to coronal streamers and coronal holes are readily apparent in the Clark Lake maps.

  15. Large-scale screening by the automated Wassermann reaction

    PubMed Central

    Wagstaff, W.; Firth, R.; Booth, J. R.; Bowley, C. C.

    1969-01-01

    In view of the drawbacks in the use of the Kahn test for large-scale screening of blood donors, mainly those of human error through work overload and fatiguability, an attempt was made to adapt an existing automated complement-fixation technique for this purpose. This paper reports the successful results of that adaptation. PMID:5776559

  16. Two-fluid effects and shear in large-scale dynamos

    NASA Astrophysics Data System (ADS)

    Lingam, Manasvi; Bhattacharjee, Amitava

    2016-10-01

    In recent times, two-fluid effects (especially the Hall term) have been increasingly explored in space and astrophysical plasmas. The large-scale and small-scale dynamos with the Hall term were explored in and. Here, we consider the role of shear (and rotation) in conjunction with the Hall term. It was recently shown, by means of a resistive MHD analysis, that the turbulent resistivity becomes tensorial in nature with negative off-diagonal components. However, the Hall term leads to additional couplings, and introduces on-diagonal contributions which can make the diagonal terms negative and drive dynamo growth. Lastly, electron inertia (a hitherto unconsidered two-fluid effect) is shown to further enhance the possibility of a turbulent anti-diffusivity, and thereby drive the large-scale dynamo. DOE Grant No. DE-AC02-09CH-11466 and NSF Grant No. AGS-1338944.

  17. Characteristics of Turbulence-driven Plasma Flow and Origin of Experimental Empirical Scalings of Intrinsic Rotation

    SciTech Connect

    Wang, W. X.; Hahm, T. S.; Ethier, S.; Rewoldt, G.; Tang, W. M.; Lee, W. W.; Diamond, P. H.

    2011-03-20

    Toroidal plasma flow driven by turbulent torque associated with nonlinear residual stress generation is shown to recover the observed key features of intrinsic rotation in experiments. Specifically, the turbulence-driven intrinsic rotation scales close to linearly with plasma gradients and the inverse of the plasma current, qualitatively reproducing empirical scalings obtained from a large experimental data base. The effect of magnetic shear on the symmetry breaking in the parallel wavenumber spectrum is identified. The origin of the current scaling is found to be the enhanced kll symmetry breaking induced by increased radial variation of the safety factor as the current decreases. The physics origin for the linear dependence of intrinsic rotation on the pressure gradient comes from the fact that both turbulence intensity and the zonal flow shear, which are two key ingredients for driving the residual stress, are increased with the strength of the turbulence drives, which are R/LTe and R/Lne for the collisionless trapped electron mode (CTEM). Highlighted results also include robust radial pinches in toroidal flow, heat and particle transport driven by CTEM turbulence, which emerge "in phase", and are shown to play important roles in determining plasma profiles. Also discussed are experimental tests proposed to validate findings from these gyrokinetic simulations.

  18. Ecohydrological modeling for large-scale environmental impact assessment.

    PubMed

    Woznicki, Sean A; Nejadhashemi, A Pouyan; Abouali, Mohammad; Herman, Matthew R; Esfahanian, Elaheh; Hamaamin, Yaseen A; Zhang, Zhen

    2016-02-01

    Ecohydrological models are frequently used to assess the biological integrity of unsampled streams. These models vary in complexity and scale, and their utility depends on their final application. Tradeoffs are usually made in model scale, where large-scale models are useful for determining broad impacts of human activities on biological conditions, and regional-scale (e.g. watershed or ecoregion) models provide stakeholders greater detail at the individual stream reach level. Given these tradeoffs, the objective of this study was to develop large-scale stream health models with reach level accuracy similar to regional-scale models thereby allowing for impacts assessments and improved decision-making capabilities. To accomplish this, four measures of biological integrity (Ephemeroptera, Plecoptera, and Trichoptera taxa (EPT), Family Index of Biotic Integrity (FIBI), Hilsenhoff Biotic Index (HBI), and fish Index of Biotic Integrity (IBI)) were modeled based on four thermal classes (cold, cold-transitional, cool, and warm) of streams that broadly dictate the distribution of aquatic biota in Michigan. The Soil and Water Assessment Tool (SWAT) was used to simulate streamflow and water quality in seven watersheds and the Hydrologic Index Tool was used to calculate 171 ecologically relevant flow regime variables. Unique variables were selected for each thermal class using a Bayesian variable selection method. The variables were then used in development of adaptive neuro-fuzzy inference systems (ANFIS) models of EPT, FIBI, HBI, and IBI. ANFIS model accuracy improved when accounting for stream thermal class rather than developing a global model.

  19. Honeycomb: Visual Analysis of Large Scale Social Networks

    NASA Astrophysics Data System (ADS)

    van Ham, Frank; Schulz, Hans-Jörg; Dimicco, Joan M.

    The rise in the use of social network sites allows us to collect large amounts of user reported data on social structures and analysis of this data could provide useful insights for many of the social sciences. This analysis is typically the domain of Social Network Analysis, and visualization of these structures often proves invaluable in understanding them. However, currently available visual analysis tools are not very well suited to handle the massive scale of this network data, and often resolve to displaying small ego networks or heavily abstracted networks. In this paper, we present Honeycomb, a visualization tool that is able to deal with much larger scale data (with millions of connections), which we illustrate by using a large scale corporate social networking site as an example. Additionally, we introduce a new probability based network metric to guide users to potentially interesting or anomalous patterns and discuss lessons learned during design and implementation.

  20. Performance Health Monitoring of Large-Scale Systems

    SciTech Connect

    Rajamony, Ram

    2014-11-20

    This report details the progress made on the ASCR funded project Performance Health Monitoring for Large Scale Systems. A large-­scale application may not achieve its full performance potential due to degraded performance of even a single subsystem. Detecting performance faults, isolating them, and taking remedial action is critical for the scale of systems on the horizon. PHM aims to develop techniques and tools that can be used to identify and mitigate such performance problems. We accomplish this through two main aspects. The PHM framework encompasses diagnostics, system monitoring, fault isolation, and performance evaluation capabilities that indicates when a performance fault has been detected, either due to an anomaly present in the system itself or due to contention for shared resources between concurrently executing jobs. Software components called the PHM Control system then build upon the capabilities provided by the PHM framework to mitigate degradation caused by performance problems.

  1. Long gradient mode and large-scale structure observables

    NASA Astrophysics Data System (ADS)

    Allahyari, Alireza; Firouzjaee, Javad T.

    2017-03-01

    We extend the study of long-mode perturbations to other large-scale observables such as cosmic rulers, galaxy-number counts, and halo bias. The long mode is a pure gradient mode that is still outside an observer's horizon. We insist that gradient-mode effects on observables vanish. It is also crucial that the expressions for observables are relativistic. This allows us to show that the effects of a gradient mode on the large-scale observables vanish identically in a relativistic framework. To study the potential modulation effect of the gradient mode on halo bias, we derive a consistency condition to the first order in gradient expansion. We find that the matter variance at a fixed physical scale is not modulated by the long gradient mode perturbations when the consistency condition holds. This shows that the contribution of long gradient modes to bias vanishes in this framework.

  2. Large-scale structure in f(T) gravity

    SciTech Connect

    Li Baojiu; Sotiriou, Thomas P.; Barrow, John D.

    2011-05-15

    In this work we study the cosmology of the general f(T) gravity theory. We express the modified Einstein equations using covariant quantities, and derive the gauge-invariant perturbation equations in covariant form. We consider a specific choice of f(T), designed to explain the observed late-time accelerating cosmic expansion without including an exotic dark energy component. Our numerical solution shows that the extra degree of freedom of such f(T) gravity models generally decays as one goes to smaller scales, and consequently its effects on scales such as galaxies and galaxies clusters are small. But on large scales, this degree of freedom can produce large deviations from the standard {Lambda}CDM scenario, leading to severe constraints on the f(T) gravity models as an explanation to the cosmic acceleration.

  3. LARGE-SCALE MOTIONS IN THE PERSEUS GALAXY CLUSTER

    SciTech Connect

    Simionescu, A.; Werner, N.; Urban, O.; Allen, S. W.; Fabian, A. C.; Sanders, J. S.; Mantz, A.; Nulsen, P. E. J.; Takei, Y.

    2012-10-01

    By combining large-scale mosaics of ROSAT PSPC, XMM-Newton, and Suzaku X-ray observations, we present evidence for large-scale motions in the intracluster medium of the nearby, X-ray bright Perseus Cluster. These motions are suggested by several alternating and interleaved X-ray bright, low-temperature, low-entropy arcs located along the east-west axis, at radii ranging from {approx}10 kpc to over a Mpc. Thermodynamic features qualitatively similar to these have previously been observed in the centers of cool-core clusters, and were successfully modeled as a consequence of the gas sloshing/swirling motions induced by minor mergers. Our observations indicate that such sloshing/swirling can extend out to larger radii than previously thought, on scales approaching the virial radius.

  4. Application of Proton Deflectometry to Z-Pinch Plasma Systems at the Mega-Ampere Scale

    NASA Astrophysics Data System (ADS)

    Mariscal, Derek; McGuffey, Chris; Valenzuela, Julio; Wei, Mingsheng; Beg, Farhat; Presura, Radu; Haque, Showera; Arias, Angel; Covington, Aaron; Sawada, Hiroshi; Chittenden, Jeremy

    2013-10-01

    Measuring magnetic fields in z-pinch plasmas is challenging. Typical laser-probing diagnostics are limited by the critical density and large density gradients, while electrical diagnostics have limited spatial resolution. We report the first demonstration of proton deflectometry of z-pinch plasma systems at the mega-ampere scale. The proton beam was produced using the 10J 0.3ps Leopard laser and coupled to z-pinch plasma produced by Zebra, a 1MA pulsed-power driver at the Nevada Terawatt Facility. The magnetic field distorted the proton beam profile, which was recorded on radiochromic film. The experimental data was compared against integrated modeling using the resistive MHD code, Gorgon, for Z-pinch plasmas, in combination with the hybrid PIC code, LSP, for proton-beam trajectory tracking. This comparison provided the field and current configuration for various plasma loads, including wire and foil z-pinches. Funded by the NSF/DoE Partnership in Basic Plasma Scienceand En- gineering under contracts DE-SC-0001992 / PHY-0903876. Use of the Nevada Terawatt Facility was supported by the US DOE, NNSA, under Contract No. DE-FC52-06NA27616.

  5. Large-scale data mining pilot project in human genome

    SciTech Connect

    Musick, R.; Fidelis, R.; Slezak, T.

    1997-05-01

    This whitepaper briefly describes a new, aggressive effort in large- scale data Livermore National Labs. The implications of `large- scale` will be clarified Section. In the short term, this effort will focus on several @ssion-critical questions of Genome project. We will adapt current data mining techniques to the Genome domain, to quantify the accuracy of inference results, and lay the groundwork for a more extensive effort in large-scale data mining. A major aspect of the approach is that we will be fully-staffed data warehousing effort in the human Genome area. The long term goal is strong applications- oriented research program in large-@e data mining. The tools, skill set gained will be directly applicable to a wide spectrum of tasks involving a for large spatial and multidimensional data. This includes applications in ensuring non-proliferation, stockpile stewardship, enabling Global Ecology (Materials Database Industrial Ecology), advancing the Biosciences (Human Genome Project), and supporting data for others (Battlefield Management, Health Care).

  6. Effects of running the Bostom Marathon on plasma concentrations of large neutral amino acids

    NASA Technical Reports Server (NTRS)

    Conlay, L. A.; Wurtman, R. J.; Lopez G-Coviella, I.; Blusztajn, J. K.; Vacanti, C. A.; Logue, M.; During, M.; Caballero, B.; Maher, T. J.; Evoniuk, G.

    1989-01-01

    Plasma large neutral amino acid concentrations were measured in thirty-seven subjects before and after completing the Boston Marathon. Concentrations of tyrosine, phenylalanine, and methionine increased, as did their 'plasma ratios' (i.e., the ratio of each amino acid's concentration to the summed plasma concentrations of the other large neutral amino acids which compete with it for brain uptake). No changes were noted in the plasma concentrations of tryptophan, leucine, isoleucine, nor valine; however, the 'plasma ratios' of valine, leucine, and isoleucine all decreased. These changes in plasma amino acid patterns may influence neurotransmitter synthesis.

  7. Large Scale Deformation of the Western US Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2001-01-01

    Destructive earthquakes occur throughout the western US Cordillera (WUSC), not just within the San Andreas fault zone. But because we do not understand the present-day large-scale deformations of the crust throughout the WUSC, our ability to assess the potential for seismic hazards in this region remains severely limited. To address this problem, we are using a large collection of Global Positioning System (GPS) networks which spans the WUSC to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work can roughly be divided into an analysis of the GPS observations to infer the deformation field across and within the entire plate boundary zone and an investigation of the implications of this deformation field regarding plate boundary dynamics.

  8. Large scale anisotropic bias from primordial non-Gaussianity

    SciTech Connect

    Baghram, Shant; Firouzjahi, Hassan; Namjoo, Mohammad Hossein E-mail: mh.namjoo@ipm.ir

    2013-08-01

    In this work we study the large scale structure bias in models of anisotropic inflation. We use the Peak Background Splitting method in Excursion Set Theory to find the scale-dependent bias. We show that the amplitude of the bias is modified by a direction-dependent factor. In the specific anisotropic inflation model which we study, the scale-dependent bias vanishes at leading order when the long wavelength mode in squeezed limit is aligned with the anisotropic direction in the sky. We also extend the scale-dependent bias formulation to the general situations with primordial anisotropy. We find some selection rules indicating that some specific parts of a generic anisotropic bispectrum is picked up by the bias parameter. We argue that the anisotropic bias is mainly sourced by the angle between the anisotropic direction and the long wavelength mode in the squeezed limit.

  9. Research on the mechanism of multiple inductively coupled plasma source for large area processing

    NASA Astrophysics Data System (ADS)

    Lee, Jangjae; Kim, Sijun; Kim, Daewoong; Kim, Kwangki; Lee, Youngseok; You, Shinjae

    2016-09-01

    In the plasma processing, inductively coupled plasma having the high-density is often used for high productivity. In large area plasma processing, the plasma can be generated by using the multi-pole connected in parallel. However, in case of this, it is difficult for power to be transferred to plasma uniformly. To solve the problem, we studied the mechanism of inductively coupled plasma connected in parallel. By using the transformer model, the multiple ICP source is treated. We also studied about the change of the plasma parameters over the time through the power balance equation and particle balance equation. Corresponding author.

  10. Variability in large-scale wind power generation: Variability in large-scale wind power generation

    SciTech Connect

    Kiviluoma, Juha; Holttinen, Hannele; Weir, David; Scharff, Richard; Söder, Lennart; Menemenlis, Nickie; Cutululis, Nicolaos A.; Danti Lopez, Irene; Lannoye, Eamonn; Estanqueiro, Ana; Gomez-Lazaro, Emilio; Bai, Jianhua; Wan, Yih-Huei; Milligan, Michael

    2015-10-25

    The paper demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability and low net load events. The comparison shows regions with low variability (Sweden, Spain and Germany), medium variability (Portugal, Ireland, Finland and Denmark) and regions with higher variability (Quebec, Bonneville Power Administration and Electric Reliability Council of Texas in North America; Gansu, Jilin and Liaoning in China; and Norway and offshore wind power in Denmark). For regions with low variability, the maximum 1 h wind ramps are below 10% of nominal capacity, and for regions with high variability, they may be close to 30%. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are autocorrelated and dependent on the operating output level. When wind power was concentrated in smaller area, there were outliers with high changes in wind output, which were not present in large areas with well-dispersed wind power.

  11. Impact of Large-scale Geological Architectures On Recharge

    NASA Astrophysics Data System (ADS)

    Troldborg, L.; Refsgaard, J. C.; Engesgaard, P.; Jensen, K. H.

    Geological and hydrogeological data constitutes the basis for assessment of ground- water flow pattern and recharge zones. The accessibility and applicability of hard ge- ological data is often a major obstacle in deriving plausible conceptual models. Nev- ertheless focus is often on parameter uncertainty caused by the effect of geological heterogeneity due to lack of hard geological data, thus neglecting the possibility of alternative conceptualizations of the large-scale geological architecture. For a catchment in the eastern part of Denmark we have constructed different geologi- cal models based on different conceptualization of the major geological trends and fa- cies architecture. The geological models are equally plausible in a conceptually sense and they are all calibrated to well head and river flow measurements. Comparison of differences in recharge zones and subsequently well protection zones emphasize the importance of assessing large-scale geological architecture in hydrological modeling on regional scale in a non-deterministic way. Geostatistical modeling carried out in a transitional probability framework shows the possibility of assessing multiple re- alizations of large-scale geological architecture from a combination of soft and hard geological information.

  12. Channel capacity of next generation large scale MIMO systems

    NASA Astrophysics Data System (ADS)

    Alshammari, A.; Albdran, S.; Matin, M.

    2016-09-01

    Information rate that can be transferred over a given bandwidth is limited by the information theory. Capacity depends on many factors such as the signal to noise ratio (SNR), channel state information (CSI) and the spatial correlation in the propagation environment. It is very important to increase spectral efficiency in order to meet the growing demand for wireless services. Thus, Multiple input multiple output (MIMO) technology has been developed and applied in most of the wireless standards and it has been very successful in increasing capacity and reliability. As the demand is still increasing, attention now is shifting towards large scale multiple input multiple output (MIMO) which has a potential of bringing orders of magnitude of improvement in spectral and energy efficiency. It has been shown that users channels decorrelate after increasing the number of antennas. As a result, inter-user interference can be avoided since energy can be focused on precise directions. This paper investigates the limits of channel capacity for large scale MIMO. We study the relation between spectral efficiency and the number of antenna N. We use time division duplex (TDD) system in order to obtain CSI using training sequence in the uplink. The same CSI is used for the downlink because the channel is reciprocal. Spectral efficiency is measured for channel model that account for small scale fading while ignoring the effect of large scale fading. It is shown the spectral efficiency can be improved significantly when compared to single antenna systems in ideal circumstances.

  13. Geospatial Optimization of Siting Large-Scale Solar Projects

    SciTech Connect

    Macknick, J.; Quinby, T.; Caulfield, E.; Gerritsen, M.; Diffendorfer, J.; Haines, S.

    2014-03-01

    Recent policy and economic conditions have encouraged a renewed interest in developing large-scale solar projects in the U.S. Southwest. However, siting large-scale solar projects is complex. In addition to the quality of the solar resource, solar developers must take into consideration many environmental, social, and economic factors when evaluating a potential site. This report describes a proof-of-concept, Web-based Geographical Information Systems (GIS) tool that evaluates multiple user-defined criteria in an optimization algorithm to inform discussions and decisions regarding the locations of utility-scale solar projects. Existing siting recommendations for large-scale solar projects from governmental and non-governmental organizations are not consistent with each other, are often not transparent in methods, and do not take into consideration the differing priorities of stakeholders. The siting assistance GIS tool we have developed improves upon the existing siting guidelines by being user-driven, transparent, interactive, capable of incorporating multiple criteria, and flexible. This work provides the foundation for a dynamic siting assistance tool that can greatly facilitate siting decisions among multiple stakeholders.

  14. Large-Scale Weather Disturbances in Mars’ Southern Extratropics

    NASA Astrophysics Data System (ADS)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2015-11-01

    Between late autumn and early spring, Mars’ middle and high latitudes within its atmosphere support strong mean thermal gradients between the tropics and poles. Observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). These extratropical weather disturbances are key components of the global circulation. Such wave-like disturbances act as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively lifted and radiatively active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are examined. Simulations that adapt Mars’ full topography compared to simulations that utilize synthetic topographies emulating key large-scale features of the southern middle latitudes indicate that Mars’ transient barotropic/baroclinic eddies are highly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). The occurrence of a southern storm zone in late winter and early spring appears to be anchored to the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre

  15. Solving large scale structure in ten easy steps with COLA

    SciTech Connect

    Tassev, Svetlin; Zaldarriaga, Matias; Eisenstein, Daniel J. E-mail: matiasz@ias.edu

    2013-06-01

    We present the COmoving Lagrangian Acceleration (COLA) method: an N-body method for solving for Large Scale Structure (LSS) in a frame that is comoving with observers following trajectories calculated in Lagrangian Perturbation Theory (LPT). Unlike standard N-body methods, the COLA method can straightforwardly trade accuracy at small-scales in order to gain computational speed without sacrificing accuracy at large scales. This is especially useful for cheaply generating large ensembles of accurate mock halo catalogs required to study galaxy clustering and weak lensing, as those catalogs are essential for performing detailed error analysis for ongoing and future surveys of LSS. As an illustration, we ran a COLA-based N-body code on a box of size 100 Mpc/h with particles of mass ≈ 5 × 10{sup 9}M{sub s}un/h. Running the code with only 10 timesteps was sufficient to obtain an accurate description of halo statistics down to halo masses of at least 10{sup 11}M{sub s}un/h. This is only at a modest speed penalty when compared to mocks obtained with LPT. A standard detailed N-body run is orders of magnitude slower than our COLA-based code. The speed-up we obtain with COLA is due to the fact that we calculate the large-scale dynamics exactly using LPT, while letting the N-body code solve for the small scales, without requiring it to capture exactly the internal dynamics of halos. Achieving a similar level of accuracy in halo statistics without the COLA method requires at least 3 times more timesteps than when COLA is employed.

  16. Solving large scale structure in ten easy steps with COLA

    NASA Astrophysics Data System (ADS)

    Tassev, Svetlin; Zaldarriaga, Matias; Eisenstein, Daniel J.

    2013-06-01

    We present the COmoving Lagrangian Acceleration (COLA) method: an N-body method for solving for Large Scale Structure (LSS) in a frame that is comoving with observers following trajectories calculated in Lagrangian Perturbation Theory (LPT). Unlike standard N-body methods, the COLA method can straightforwardly trade accuracy at small-scales in order to gain computational speed without sacrificing accuracy at large scales. This is especially useful for cheaply generating large ensembles of accurate mock halo catalogs required to study galaxy clustering and weak lensing, as those catalogs are essential for performing detailed error analysis for ongoing and future surveys of LSS. As an illustration, we ran a COLA-based N-body code on a box of size 100 Mpc/h with particles of mass ≈ 5 × 109Msolar/h. Running the code with only 10 timesteps was sufficient to obtain an accurate description of halo statistics down to halo masses of at least 1011Msolar/h. This is only at a modest speed penalty when compared to mocks obtained with LPT. A standard detailed N-body run is orders of magnitude slower than our COLA-based code. The speed-up we obtain with COLA is due to the fact that we calculate the large-scale dynamics exactly using LPT, while letting the N-body code solve for the small scales, without requiring it to capture exactly the internal dynamics of halos. Achieving a similar level of accuracy in halo statistics without the COLA method requires at least 3 times more timesteps than when COLA is employed.

  17. Laser Plasma Particle Accelerators: Large Fields for Smaller Facility Sources

    SciTech Connect

    Geddes, Cameron G.R.; Cormier-Michel, Estelle; Esarey, Eric H.; Schroeder, Carl B.; Vay, Jean-Luc; Leemans, Wim P.; Bruhwiler, David L.; Cary, John R.; Cowan, Ben; Durant, Marc; Hamill, Paul; Messmer, Peter; Mullowney, Paul; Nieter, Chet; Paul, Kevin; Shasharina, Svetlana; Veitzer, Seth; Weber, Gunther; Rubel, Oliver; Ushizima, Daniela; Bethel, Wes; Wu, John

    2009-03-20

    Compared to conventional particle accelerators, plasmas can sustain accelerating fields that are thousands of times higher. To exploit this ability, massively parallel SciDAC particle simulations provide physical insight into the development of next-generation accelerators that use laser-driven plasma waves. These plasma-based accelerators offer a path to more compact, ultra-fast particle and radiation sources for probing the subatomic world, for studying new materials and new technologies, and for medical applications.

  18. Intensive agriculture erodes β-diversity at large scales.

    PubMed

    Karp, Daniel S; Rominger, Andrew J; Zook, Jim; Ranganathan, Jai; Ehrlich, Paul R; Daily, Gretchen C

    2012-09-01

    Biodiversity is declining from unprecedented land conversions that replace diverse, low-intensity agriculture with vast expanses under homogeneous, intensive production. Despite documented losses of species richness, consequences for β-diversity, changes in community composition between sites, are largely unknown, especially in the tropics. Using a 10-year data set on Costa Rican birds, we find that low-intensity agriculture sustained β-diversity across large scales on a par with forest. In high-intensity agriculture, low local (α) diversity inflated β-diversity as a statistical artefact. Therefore, at small spatial scales, intensive agriculture appeared to retain β-diversity. Unlike in forest or low-intensity systems, however, high-intensity agriculture also homogenised vegetation structure over large distances, thereby decoupling the fundamental ecological pattern of bird communities changing with geographical distance. This ~40% decline in species turnover indicates a significant decline in β-diversity at large spatial scales. These findings point the way towards multi-functional agricultural systems that maintain agricultural productivity while simultaneously conserving biodiversity.

  19. Alteration of Large-Scale Chromatin Structure by Estrogen Receptor

    PubMed Central

    Nye, Anne C.; Rajendran, Ramji R.; Stenoien, David L.; Mancini, Michael A.; Katzenellenbogen, Benita S.; Belmont, Andrew S.

    2002-01-01

    The estrogen receptor (ER), a member of the nuclear hormone receptor superfamily important in human physiology and disease, recruits coactivators which modify local chromatin structure. Here we describe effects of ER on large-scale chromatin structure as visualized in live cells. We targeted ER to gene-amplified chromosome arms containing large numbers of lac operator sites either directly, through a lac repressor-ER fusion protein (lac rep-ER), or indirectly, by fusing lac repressor with the ER interaction domain of the coactivator steroid receptor coactivator 1. Significant decondensation of large-scale chromatin structure, comparable to that produced by the ∼150-fold-stronger viral protein 16 (VP16) transcriptional activator, was produced by ER in the absence of estradiol using both approaches. Addition of estradiol induced a partial reversal of this unfolding by green fluorescent protein-lac rep-ER but not by wild-type ER recruited by a lac repressor-SRC570-780 fusion protein. The chromatin decondensation activity did not require transcriptional activation by ER nor did it require ligand-induced coactivator interactions, and unfolding did not correlate with histone hyperacetylation. Ligand-induced coactivator interactions with helix 12 of ER were necessary for the partial refolding of chromatin in response to estradiol using the lac rep-ER tethering system. This work demonstrates that when tethered or recruited to DNA, ER possesses a novel large-scale chromatin unfolding activity. PMID:11971975

  20. Assessing salivary cortisol in large-scale, epidemiological research.

    PubMed

    Adam, Emma K; Kumari, Meena

    2009-11-01

    Salivary cortisol measures are increasingly being incorporated into large-scale, population-based, or epidemiological research, in which participants are selected to be representative of particular communities or populations of interest, and sample sizes are in the order of hundreds to tens of thousands of participants. These approaches to studying salivary cortisol provide important advantages but pose a set of challenges. The representative nature of sampling, and large samples sizes associated with population-based research offer high generalizability and power, and the ability to examine cortisol functioning in relation to: (a) a wide range of social environments; (b) a diverse array individuals and groups; and (c) a broad set of pre-disease and disease outcomes. The greater importance of high response rates (to maintain generalizability) and higher costs associated with this type of large-scale research, however, requires special adaptations of existing ambulatory cortisol protocols. These include: using the most efficient sample collection protocol possible that still adequately address the specific cortisol-related questions at hand, and ensuring the highest possible response and compliance rates among those individuals invited to participate. Examples of choices made, response rates obtained, and examples of results obtained from existing epidemiological cortisol studies are offered, as are suggestions for the modeling and interpretation of salivary cortisol data obtained in large-scale epidemiological research.

  1. Large-scale biodiversity patterns in freshwater phytoplankton.

    PubMed

    Stomp, Maayke; Huisman, Jef; Mittelbach, Gary G; Litchman, Elena; Klausmeier, Christopher A

    2011-11-01

    Our planet shows striking gradients in the species richness of plants and animals, from high biodiversity in the tropics to low biodiversity in polar and high-mountain regions. Recently, similar patterns have been described for some groups of microorganisms, but the large-scale biogeographical distribution of freshwater phytoplankton diversity is still largely unknown. We examined the species diversity of freshwater phytoplankton sampled from 540 lakes and reservoirs distributed across the continental United States and found strong latitudinal, longitudinal, and altitudinal gradients in phytoplankton biodiversity, demonstrating that microorganisms can show substantial geographic variation in biodiversity. Detailed analysis using structural equation models indicated that these large-scale biodiversity gradients in freshwater phytoplankton diversity were mainly driven by local environmental factors, although there were residual direct effects of latitude, longitude, and altitude as well. Specifically, we found that phytoplankton species richness was an increasing saturating function of lake chlorophyll a concentration, increased with lake surface area and possibly increased with water temperature, resembling effects of productivity, habitat area, and temperature on diversity patterns commonly observed for macroorganisms. In turn, these local environmental factors varied along latitudinal, longitudinal, and altitudinal gradients. These results imply that changes in land use or climate that affect these local environmental factors are likely to have major impacts on large-scale biodiversity patterns of freshwater phytoplankton.

  2. Clusters as cornerstones of large-scale structure.

    NASA Astrophysics Data System (ADS)

    Gottlöber, S.; Retzlaff, J.; Turchaninov, V.

    1997-04-01

    Galaxy clusters are one of the best tracers of large-scale structure in the Universe on scales well above 100 Mpc. The authors investigate here the clustering properties of a redshift sample of Abell/ACO clusters and compare the observational sample with mock samples constructed from N-body simulations on the basis of four different cosmological models. The authors discuss the power spectrum, the Minkowski functionals and the void statistics of these samples and conclude, that the SCDM and TCDM models are ruled out whereas the ACDM and BSI models are in agreement with the observational data.

  3. Large-Scale Patterns of Filament Channels and Filaments

    NASA Astrophysics Data System (ADS)

    Mackay, Duncan

    2016-07-01

    In this review the properties and large-scale patterns of filament channels and filaments will be considered. Initially, the global formation locations of filament channels and filaments are discussed, along with their hemispheric pattern. Next, observations of the formation of filament channels and filaments are described where two opposing views are considered. Finally, the wide range of models that have been constructed to consider the formation of filament channels and filaments over long time-scales are described, along with the origin of the hemispheric pattern of filaments.

  4. Large-Scale Optimization for Bayesian Inference in Complex Systems

    SciTech Connect

    Willcox, Karen; Marzouk, Youssef

    2013-11-12

    The SAGUARO (Scalable Algorithms for Groundwater Uncertainty Analysis and Robust Optimization) Project focused on the development of scalable numerical algorithms for large-scale Bayesian inversion in complex systems that capitalize on advances in large-scale simulation-based optimization and inversion methods. The project was a collaborative effort among MIT, the University of Texas at Austin, Georgia Institute of Technology, and Sandia National Laboratories. The research was directed in three complementary areas: efficient approximations of the Hessian operator, reductions in complexity of forward simulations via stochastic spectral approximations and model reduction, and employing large-scale optimization concepts to accelerate sampling. The MIT--Sandia component of the SAGUARO Project addressed the intractability of conventional sampling methods for large-scale statistical inverse problems by devising reduced-order models that are faithful to the full-order model over a wide range of parameter values; sampling then employs the reduced model rather than the full model, resulting in very large computational savings. Results indicate little effect on the computed posterior distribution. On the other hand, in the Texas--Georgia Tech component of the project, we retain the full-order model, but exploit inverse problem structure (adjoint-based gradients and partial Hessian information of the parameter-to-observation map) to implicitly extract lower dimensional information on the posterior distribution; this greatly speeds up sampling methods, so that fewer sampling points are needed. We can think of these two approaches as ``reduce then sample'' and ``sample then reduce.'' In fact, these two approaches are complementary, and can be used in conjunction with each other. Moreover, they both exploit deterministic inverse problem structure, in the form of adjoint-based gradient and Hessian information of the underlying parameter-to-observation map, to achieve their

  5. Large- to small-scale dynamo in domains of large aspect ratio: kinematic regime

    NASA Astrophysics Data System (ADS)

    Shumaylova, Valeria; Teed, Robert J.; Proctor, Michael R. E.

    2017-04-01

    The Sun's magnetic field exhibits coherence in space and time on much larger scales than the turbulent convection that ultimately powers the dynamo. In this work, we look for numerical evidence of a large-scale magnetic field as the magnetic Reynolds number, Rm, is increased. The investigation is based on the simulations of the induction equation in elongated periodic boxes. The imposed flows considered are the standard ABC flow (named after Arnold, Beltrami & Childress) with wavenumber ku = 1 (small-scale) and a modulated ABC flow with wavenumbers ku = m, 1, 1 ± m, where m is the wavenumber corresponding to the long-wavelength perturbation on the scale of the box. The critical magnetic Reynolds number R_m^{crit} decreases as the permitted scale separation in the system increases, such that R_m^{crit} ∝ [L_x/L_z]^{-1/2}. The results show that the α-effect derived from the mean-field theory ansatz is valid for a small range of Rm after which small scale dynamo instability occurs and the mean-field approximation is no longer valid. The transition from large- to small-scale dynamo is smooth and takes place in two stages: a fast transition into a predominantly small-scale magnetic energy state and a slower transition into even smaller scales. In the range of Rm considered, the most energetic Fourier component corresponding to the structure in the long x-direction has twice the length-scale of the forcing scale. The long-wavelength perturbation imposed on the ABC flow in the modulated case is not preserved in the eigenmodes of the magnetic field.

  6. Modelling large-scale halo bias using the bispectrum

    NASA Astrophysics Data System (ADS)

    Pollack, Jennifer E.; Smith, Robert E.; Porciani, Cristiano

    2012-03-01

    We study the relation between the density distribution of tracers for large-scale structure and the underlying matter distribution - commonly termed bias - in the Λ cold dark matter framework. In particular, we examine the validity of the local model of biasing at quadratic order in the matter density. This model is characterized by parameters b1 and b2. Using an ensemble of N-body simulations, we apply several statistical methods to estimate the parameters. We measure halo and matter fluctuations smoothed on various scales. We find that, whilst the fits are reasonably good, the parameters vary with smoothing scale. We argue that, for real-space measurements, owing to the mixing of wavemodes, no smoothing scale can be found for which the parameters are independent of smoothing. However, this is not the case in Fourier space. We measure halo and halo-mass power spectra and from these construct estimates of the effective large-scale bias as a guide for b1. We measure the configuration dependence of the halo bispectra Bhhh and reduced bispectra Qhhh for very large-scale k-space triangles. From these data, we constrain b1 and b2, taking into account the full bispectrum covariance matrix. Using the lowest order perturbation theory, we find that for Bhhh the best-fitting parameters are in reasonable agreement with one another as the triangle scale is varied, although the fits become poor as smaller scales are included. The same is true for Qhhh. The best-fitting values were found to depend on the discreteness correction. This led us to consider halo-mass cross-bispectra. The results from these statistics supported our earlier findings. We then developed a test to explore whether the inconsistency in the recovered bias parameters could be attributed to missing higher order corrections in the models. We prove that low-order expansions are not sufficiently accurate to model the data, even on scales k1˜ 0.04 h Mpc-1. If robust inferences concerning bias are to be drawn

  7. Large scale rigidity-based flexibility analysis of biomolecules

    PubMed Central

    Streinu, Ileana

    2016-01-01

    KINematics And RIgidity (KINARI) is an on-going project for in silico flexibility analysis of proteins. The new version of the software, Kinari-2, extends the functionality of our free web server KinariWeb, incorporates advanced web technologies, emphasizes the reproducibility of its experiments, and makes substantially improved tools available to the user. It is designed specifically for large scale experiments, in particular, for (a) very large molecules, including bioassemblies with high degree of symmetry such as viruses and crystals, (b) large collections of related biomolecules, such as those obtained through simulated dilutions, mutations, or conformational changes from various types of dynamics simulations, and (c) is intended to work as seemlessly as possible on the large, idiosyncratic, publicly available repository of biomolecules, the Protein Data Bank. We describe the system design, along with the main data processing, computational, mathematical, and validation challenges underlying this phase of the KINARI project. PMID:26958583

  8. Scale-Similar Models for Large-Eddy Simulations

    NASA Technical Reports Server (NTRS)

    Sarghini, F.

    1999-01-01

    Scale-similar models employ multiple filtering operations to identify the smallest resolved scales, which have been shown to be the most active in the interaction with the unresolved subgrid scales. They do not assume that the principal axes of the strain-rate tensor are aligned with those of the subgrid-scale stress (SGS) tensor, and allow the explicit calculation of the SGS energy. They can provide backscatter in a numerically stable and physically realistic manner, and predict SGS stresses in regions that are well correlated with the locations where large Reynolds stress occurs. In this paper, eddy viscosity and mixed models, which include an eddy-viscosity part as well as a scale-similar contribution, are applied to the simulation of two flows, a high Reynolds number plane channel flow, and a three-dimensional, nonequilibrium flow. The results show that simulations without models or with the Smagorinsky model are unable to predict nonequilibrium effects. Dynamic models provide an improvement of the results: the adjustment of the coefficient results in more accurate prediction of the perturbation from equilibrium. The Lagrangian-ensemble approach [Meneveau et al., J. Fluid Mech. 319, 353 (1996)] is found to be very beneficial. Models that included a scale-similar term and a dissipative one, as well as the Lagrangian ensemble averaging, gave results in the best agreement with the direct simulation and experimental data.

  9. Resolving the paradox of oceanic large-scale balance and small-scale mixing.

    PubMed

    Marino, R; Pouquet, A; Rosenberg, D

    2015-03-20

    A puzzle of oceanic dynamics is the contrast between the observed geostrophic balance, involving gravity, pressure gradient, and Coriolis forces, and the necessary turbulent transport: in the former case, energy flows to large scales, leading to spectral condensation, whereas in the latter, it is transferred to small scales, where dissipation prevails. The known bidirectional constant-flux energy cascade maintaining both geostrophic balance and mixing tends towards flux equilibration as turbulence strengthens, contradicting models and recent observations which find a dominant large-scale flux. Analyzing a large ensemble of high-resolution direct numerical simulations of the Boussinesq equations in the presence of rotation and no salinity, we show that the ratio of the dual energy flux to large and to small scales agrees with observations, and we predict that it scales with the inverse of the Froude and Rossby numbers when stratification is (realistically) stronger than rotation. Furthermore, we show that the kinetic and potential energies separately undergo a bidirectional transfer to larger and smaller scales. Altogether, this allows for small-scale mixing which drives the global oceanic circulation and will thus potentially lead to more accurate modeling of climate dynamics.

  10. Electrostatic Equations for Large Scale Plasma Simulation Studies.

    DTIC Science & Technology

    1984-07-19

    iv i/Xj- v~d 1- vb)1X + g /X)I +L diSevb g/X) x~ 9 (7) and (~d v/X -vb Xv ) d v~ex0 Yn D ein en e + d bJ -X2 ~vd /X 2 + Svb X - +~ vbJ ~tXg + X -12~ d...ahIE x /B BV) +~{S~2~ven -s i~i/A + V(Se - S1)A - + S~fX) x(10) e4 e S Oi5 0-7 where S a e D -e .2£𔃼 sI = -D- (d e+ vbj 2 2= o/B AS v x2 + e en 1 VinJ

  11. Large-scale genotoxicity assessments in the marine environment.

    PubMed Central

    Hose, J E

    1994-01-01

    There are a number of techniques for detecting genotoxicity in the marine environment, and many are applicable to large-scale field assessments. Certain tests can be used to evaluate responses in target organisms in situ while others utilize surrogate organisms exposed to field samples in short-term laboratory bioassays. Genotoxicity endpoints appear distinct from traditional toxicity endpoints, but some have chemical or ecotoxicologic correlates. One versatile end point, the frequency of anaphase aberrations, has been used in several large marine assessments to evaluate genotoxicity in the New York Bight, in sediment from San Francisco Bay, and following the Exxon Valdez oil spill. PMID:7713029

  12. Large Scale Composite Manufacturing for Heavy Lift Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Stavana, Jacob; Cohen, Leslie J.; Houseal, Keth; Pelham, Larry; Lort, Richard; Zimmerman, Thomas; Sutter, James; Western, Mike; Harper, Robert; Stuart, Michael

    2012-01-01

    Risk reduction for the large scale composite manufacturing is an important goal to produce light weight components for heavy lift launch vehicles. NASA and an industry team successfully employed a building block approach using low-cost Automated Tape Layup (ATL) of autoclave and Out-of-Autoclave (OoA) prepregs. Several large, curved sandwich panels were fabricated at HITCO Carbon Composites. The aluminum honeycomb core sandwich panels are segments of a 1/16th arc from a 10 meter cylindrical barrel. Lessons learned highlight the manufacturing challenges required to produce light weight composite structures such as fairings for heavy lift launch vehicles.

  13. Large-scale genotoxicity assessments in the marine environment

    SciTech Connect

    Hose, J.E.

    1994-12-01

    There are a number of techniques for detecting genotoxicity in the marine environment, and many are applicable to large-scale field assessments. Certain tests can be used to evaluate responses in target organisms in situ while others utilize surrogate organisms exposed to field samples in short-term laboratory bioassays. Genotoxicity endpoints appear distinct from traditional toxicity endpoints, but some have chemical or ecotoxicologic correlates. One versatile end point, the frequency of anaphase aberrations, has been used in several large marine assessments to evaluate genotoxicity in the New York Bight, in sediment from San Francisco Bay, and following the Exxon Valdez oil spill. 31 refs., 2 tabs.

  14. Frequency domain multiplexing for large-scale bolometer arrays

    SciTech Connect

    Spieler, Helmuth

    2002-05-31

    The development of planar fabrication techniques for superconducting transition-edge sensors has brought large-scale arrays of 1000 pixels or more to the realm of practicality. This raises the problem of reading out a large number of sensors with a tractable number of connections. A possible solution is frequency-domain multiplexing. I summarize basic principles, present various circuit topologies, and discuss design trade-offs, noise performance, cross-talk and dynamic range. The design of a practical device and its readout system is described with a discussion of fabrication issues, practical limits and future prospects.

  15. Decentrally stabilizable linear and bilinear large-scale systems

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.; Vukcevic, M. B.

    1977-01-01

    Two classes of large-scale systems are identified, which can always be stabilized by decentralized feedback control. For the class of systems composed of interconnected linear subsystems, we can choose local controllers for the subsystems to achieve stability of the overall system. The same linear feedback scheme can be used to stabilize a class of linear systems with bilinear interconnections. In this case, however, the scheme is used to establish a finite region of stability for the overall system. The stabilization algorithm is applied to the design of a control system for the Large-Space Telescope.

  16. Large-scale Observations of the Magnetopause by Cluster

    NASA Astrophysics Data System (ADS)

    Foullon, Claire

    2014-05-01

    The magnetopause and its adjacent boundary layers are a key science target for many satellite missions. They have been sampled, at the same time, either locally by a maximum of 4 to 5 closely spaced spacecraft (from the Cluster constellation and the Double Star TC-1 satellite) or on larger scales by missions such as Geotail, Cluster and THEMIS. Unfortunately, none of the spacecraft configurations has so far permitted the 'evolution' of perturbations along their main direction of propagation to be tracked. The study of the evolution of magnetic field and plasma perturbations, such as Kelvin-Helmholtz (KH) waves or Flux Transfer Events (FTEs), together with the (associated or not) generation of Kinetic Alfvén Waves (KAWs) and the turbulence developing at the flank magnetopause boundary layer, is important for our understanding of the mechanisms that mediate solar wind plasma entry into the magnetosphere, i.e. magnetic reconnection and diffusive processes. The Cluster Guest Investigator (GI) proposal implemented in November 2012 targeted inter-spacecraft separations of ~1 RE necessary to relate disturbances and deduce their evolution. It resulted in separations of up to 36,000 km across the constellation at the magnetopause and was the largest separation ever for the Cluster mission. In this invited talk, I will present the first results from the Cluster GI observations of magnetopause boundary layer.

  17. Large-scale Observations of the Magnetopause by Cluster (Invited)

    NASA Astrophysics Data System (ADS)

    Foullon, C.

    2013-12-01

    The magnetopause and its adjacent boundary layers are a key science target for many satellite missions. They have been sampled, at the same time, either locally by a maximum of 4 to 5 closely spaced spacecraft (from the Cluster constellation and the Double Star TC-1 satellite) or on larger scales by missions such as Geotail, Cluster and THEMIS. Unfortunately, none of the spacecraft configurations has so far permitted the 'evolution' of perturbations along their main direction of propagation to be tracked. The study of the evolution of magnetic field and plasma perturbations, such as Kelvin-Helmholtz (KH) waves or Flux Transfer Events (FTEs), together with the (associated or not) generation of Kinetic Alfvén Waves (KAWs) and the turbulence developing at the flank magnetopause boundary layer, is important for our understanding of the mechanisms that mediate solar wind plasma entry into the magnetosphere, i.e. magnetic reconnection and diffusive processes. The Cluster Guest Investigator (GI) proposal implemented in November 2012 targeted inter-spacecraft separations of ~1 RE necessary to relate disturbances and deduce their evolution. It resulted in separations of up to 36,000 km across the constellation at the magnetopause and was the largest separation ever for the Cluster mission. In this invited talk, I will present the first results from the Cluster GI observations of magnetopause boundary layer.

  18. Anisotropy and nonuniversality in scaling laws of the large-scale energy spectrum in rotating turbulence.

    PubMed

    Sen, Amrik; Mininni, Pablo D; Rosenberg, Duane; Pouquet, Annick

    2012-09-01

    Rapidly rotating turbulent flow is characterized by the emergence of columnar structures that are representative of quasi-two-dimensional behavior of the flow. It is known that when energy is injected into the fluid at an intermediate scale Lf, it cascades towards smaller as well as larger scales. In this paper we analyze the flow in the inverse cascade range at a small but fixed Rossby number, Rof≈0.05. Several numerical simulations with helical and nonhelical forcing functions are considered in periodic boxes with unit aspect ratio. In order to resolve the inverse cascade range with reasonably large Reynolds number, the analysis is based on large eddy simulations which include the effect of helicity on eddy viscosity and eddy noise. Thus, we model the small scales and resolve explicitly the large scales. We show that the large-scale energy spectrum has at least two solutions: one that is consistent with Kolmogorov-Kraichnan-Batchelor-Leith phenomenology for the inverse cascade of energy in two-dimensional (2D) turbulence with a ∼k⊥-5/3 scaling, and the other that corresponds to a steeper ∼k⊥-3 spectrum in which the three-dimensional (3D) modes release a substantial fraction of their energy per unit time to the 2D modes. The spectrum that emerges depends on the anisotropy of the forcing function, the former solution prevailing for forcings in which more energy is injected into the 2D modes while the latter prevails for isotropic forcing. In the case of anisotropic forcing, whence the energy goes from the 2D to the 3D modes at low wave numbers, large-scale shear is created, resulting in a time scale τsh, associated with shear, thereby producing a ∼k-1 spectrum for the total energy with the horizontal energy of the 2D modes still following a ∼k⊥-5/3 scaling.

  19. A first large-scale flood inundation forecasting model

    SciTech Connect

    Schumann, Guy J-P; Neal, Jeffrey C.; Voisin, Nathalie; Andreadis, Konstantinos M.; Pappenberger, Florian; Phanthuwongpakdee, Kay; Hall, Amanda C.; Bates, Paul D.

    2013-11-04

    At present continental to global scale flood forecasting focusses on predicting at a point discharge, with little attention to the detail and accuracy of local scale inundation predictions. Yet, inundation is actually the variable of interest and all flood impacts are inherently local in nature. This paper proposes a first large scale flood inundation ensemble forecasting model that uses best available data and modeling approaches in data scarce areas and at continental scales. The model was built for the Lower Zambezi River in southeast Africa to demonstrate current flood inundation forecasting capabilities in large data-scarce regions. The inundation model domain has a surface area of approximately 170k km2. ECMWF meteorological data were used to force the VIC (Variable Infiltration Capacity) macro-scale hydrological model which simulated and routed daily flows to the input boundary locations of the 2-D hydrodynamic model. Efficient hydrodynamic modeling over large areas still requires model grid resolutions that are typically larger than the width of many river channels that play a key a role in flood wave propagation. We therefore employed a novel sub-grid channel scheme to describe the river network in detail whilst at the same time representing the floodplain at an appropriate and efficient scale. The modeling system was first calibrated using water levels on the main channel from the ICESat (Ice, Cloud, and land Elevation Satellite) laser altimeter and then applied to predict the February 2007 Mozambique floods. Model evaluation showed that simulated flood edge cells were within a distance of about 1 km (one model resolution) compared to an observed flood edge of the event. Our study highlights that physically plausible parameter values and satisfactory performance can be achieved at spatial scales ranging from tens to several hundreds of thousands of km2 and at model grid resolutions up to several km2. However, initial model test runs in forecast mode

  20. The Large Scale Synthesis of Aligned Plate Nanostructures

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Nash, Philip; Liu, Tian; Zhao, Naiqin; Zhu, Shengli

    2016-07-01

    We propose a novel technique for the large-scale synthesis of aligned-plate nanostructures that are self-assembled and self-supporting. The synthesis technique involves developing nanoscale two-phase microstructures through discontinuous precipitation followed by selective etching to remove one of the phases. The method may be applied to any alloy system in which the discontinuous precipitation transformation goes to completion. The resulting structure may have many applications in catalysis, filtering and thermal management depending on the phase selection and added functionality through chemical reaction with the retained phase. The synthesis technique is demonstrated using the discontinuous precipitation of a γ‧ phase, (Ni, Co)3Al, followed by selective dissolution of the γ matrix phase. The production of the nanostructure requires heat treatments on the order of minutes and can be performed on a large scale making this synthesis technique of great economic potential.

  1. Large-scale quantum networks based on graphs

    NASA Astrophysics Data System (ADS)

    Epping, Michael; Kampermann, Hermann; Bruß, Dagmar

    2016-05-01

    Society relies and depends increasingly on information exchange and communication. In the quantum world, security and privacy is a built-in feature for information processing. The essential ingredient for exploiting these quantum advantages is the resource of entanglement, which can be shared between two or more parties. The distribution of entanglement over large distances constitutes a key challenge for current research and development. Due to losses of the transmitted quantum particles, which typically scale exponentially with the distance, intermediate quantum repeater stations are needed. Here we show how to generalise the quantum repeater concept to the multipartite case, by describing large-scale quantum networks, i.e. network nodes and their long-distance links, consistently in the language of graphs and graph states. This unifying approach comprises both the distribution of multipartite entanglement across the network, and the protection against errors via encoding. The correspondence to graph states also provides a tool for optimising the architecture of quantum networks.

  2. Large-scale linear nonparallel support vector machine solver.

    PubMed

    Tian, Yingjie; Ping, Yuan

    2014-02-01

    Twin support vector machines (TWSVMs), as the representative nonparallel hyperplane classifiers, have shown the effectiveness over standard SVMs from some aspects. However, they still have some serious defects restricting their further study and real applications: (1) They have to compute and store the inverse matrices before training, it is intractable for many applications where data appear with a huge number of instances as well as features; (2) TWSVMs lost the sparseness by using a quadratic loss function making the proximal hyperplane close enough to the class itself. This paper proposes a Sparse Linear Nonparallel Support Vector Machine, termed as L1-NPSVM, to deal with large-scale data based on an efficient solver-dual coordinate descent (DCD) method. Both theoretical analysis and experiments indicate that our method is not only suitable for large scale problems, but also performs as good as TWSVMs and SVMs.

  3. Electron drift in a large scale solid xenon

    SciTech Connect

    Yoo, J.; Jaskierny, W. F.

    2015-08-21

    A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7 cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163 K), the drift speed is 0.193 ± 0.003 cm/μs while the drift speed in the solid phase (157 K) is 0.397 ± 0.006 cm/μs at 900 V/cm over 8.0 cm of uniform electric fields. Furthermore, it is demonstrated that a factor two faster electron drift speed in solid phase xenon compared to that in liquid in a large scale solid xenon.

  4. Instrumentation Development for Large Scale Hypersonic Inflatable Aerodynamic Decelerator Characterization

    NASA Technical Reports Server (NTRS)

    Swanson, Gregory T.; Cassell, Alan M.

    2011-01-01

    Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology is currently being considered for multiple atmospheric entry applications as the limitations of traditional entry vehicles have been reached. The Inflatable Re-entry Vehicle Experiment (IRVE) has successfully demonstrated this technology as a viable candidate with a 3.0 m diameter vehicle sub-orbital flight. To further this technology, large scale HIADs (6.0 8.5 m) must be developed and tested. To characterize the performance of large scale HIAD technology new instrumentation concepts must be developed to accommodate the flexible nature inflatable aeroshell. Many of the concepts that are under consideration for the HIAD FY12 subsonic wind tunnel test series are discussed below.

  5. The workshop on iterative methods for large scale nonlinear problems

    SciTech Connect

    Walker, H.F.; Pernice, M.

    1995-12-01

    The aim of the workshop was to bring together researchers working on large scale applications with numerical specialists of various kinds. Applications that were addressed included reactive flows (combustion and other chemically reacting flows, tokamak modeling), porous media flows, cardiac modeling, chemical vapor deposition, image restoration, macromolecular modeling, and population dynamics. Numerical areas included Newton iterative (truncated Newton) methods, Krylov subspace methods, domain decomposition and other preconditioning methods, large scale optimization and optimal control, and parallel implementations and software. This report offers a brief summary of workshop activities and information about the participants. Interested readers are encouraged to look into an online proceedings available at http://www.usi.utah.edu/logan.proceedings. In this, the material offered here is augmented with hypertext abstracts that include links to locations such as speakers` home pages, PostScript copies of talks and papers, cross-references to related talks, and other information about topics addresses at the workshop.

  6. GAIA: A WINDOW TO LARGE-SCALE MOTIONS

    SciTech Connect

    Nusser, Adi; Branchini, Enzo; Davis, Marc E-mail: branchin@fis.uniroma3.it

    2012-08-10

    Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, because of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.

  7. The Large Scale Synthesis of Aligned Plate Nanostructures

    PubMed Central

    Zhou, Yang; Nash, Philip; Liu, Tian; Zhao, Naiqin; Zhu, Shengli

    2016-01-01

    We propose a novel technique for the large-scale synthesis of aligned-plate nanostructures that are self-assembled and self-supporting. The synthesis technique involves developing nanoscale two-phase microstructures through discontinuous precipitation followed by selective etching to remove one of the phases. The method may be applied to any alloy system in which the discontinuous precipitation transformation goes to completion. The resulting structure may have many applications in catalysis, filtering and thermal management depending on the phase selection and added functionality through chemical reaction with the retained phase. The synthesis technique is demonstrated using the discontinuous precipitation of a γ′ phase, (Ni, Co)3Al, followed by selective dissolution of the γ matrix phase. The production of the nanostructure requires heat treatments on the order of minutes and can be performed on a large scale making this synthesis technique of great economic potential. PMID:27439672

  8. Lagrangian space consistency relation for large scale structure

    SciTech Connect

    Horn, Bart; Hui, Lam; Xiao, Xiao E-mail: lh399@columbia.edu

    2015-09-01

    Consistency relations, which relate the squeezed limit of an (N+1)-point correlation function to an N-point function, are non-perturbative symmetry statements that hold even if the associated high momentum modes are deep in the nonlinear regime and astrophysically complex. Recently, Kehagias and Riotto and Peloso and Pietroni discovered a consistency relation applicable to large scale structure. We show that this can be recast into a simple physical statement in Lagrangian space: that the squeezed correlation function (suitably normalized) vanishes. This holds regardless of whether the correlation observables are at the same time or not, and regardless of whether multiple-streaming is present. The simplicity of this statement suggests that an analytic understanding of large scale structure in the nonlinear regime may be particularly promising in Lagrangian space.

  9. Unstable `black branes' from scaled membranes at large D

    NASA Astrophysics Data System (ADS)

    Dandekar, Yogesh; Mazumdar, Subhajit; Minwalla, Shiraz; Saha, Arunabha

    2016-12-01

    It has recently been demonstrated that the dynamics of black holes at large D can be recast as a set of non gravitational membrane equations. These membrane equations admit a simple static solution with shape S D- p-2× R p,1. In this note we study the equations for small fluctuations about this solution in a limit in which amplitude and length scale of the fluctuations are simultaneously scaled to zero as D is taken to infinity. We demonstrate that the resultant nonlinear equations, which capture the Gregory-Laflamme instability and its end point, exactly agree with the effective dynamical `black brane' equations of Emparan Suzuki and Tanabe. Our results thus identify the `black brane' equations as a special limit of the membrane equations and so unify these approaches to large D black hole dynamics.

  10. In the fast lane: large-scale bacterial genome engineering.

    PubMed

    Fehér, Tamás; Burland, Valerie; Pósfai, György

    2012-07-31

    The last few years have witnessed rapid progress in bacterial genome engineering. The long-established, standard ways of DNA synthesis, modification, transfer into living cells, and incorporation into genomes have given way to more effective, large-scale, robust genome modification protocols. Expansion of these engineering capabilities is due to several factors. Key advances include: (i) progress in oligonucleotide synthesis and in vitro and in vivo assembly methods, (ii) optimization of recombineering techniques, (iii) introduction of parallel, large-scale, combinatorial, and automated genome modification procedures, and (iv) rapid identification of the modifications by barcode-based analysis and sequencing. Combination of the brute force of these techniques with sophisticated bioinformatic design and modeling opens up new avenues for the analysis of gene functions and cellular network interactions, but also in engineering more effective producer strains. This review presents a summary of recent technological advances in bacterial genome engineering.

  11. Electron drift in a large scale solid xenon

    DOE PAGES

    Yoo, J.; Jaskierny, W. F.

    2015-08-21

    A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7 cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163 K), the drift speed is 0.193 ± 0.003 cm/μs while the drift speed in the solid phase (157 K) is 0.397 ± 0.006 cm/μs at 900 V/cm over 8.0 cm of uniform electric fields. Furthermore, it is demonstrated that a factor twomore » faster electron drift speed in solid phase xenon compared to that in liquid in a large scale solid xenon.« less

  12. Applications of large-scale density functional theory in biology

    NASA Astrophysics Data System (ADS)

    Cole, Daniel J.; Hine, Nicholas D. M.

    2016-10-01

    Density functional theory (DFT) has become a routine tool for the computation of electronic structure in the physics, materials and chemistry fields. Yet the application of traditional DFT to problems in the biological sciences is hindered, to a large extent, by the unfavourable scaling of the computational effort with system size. Here, we review some of the major software and functionality advances that enable insightful electronic structure calculations to be performed on systems comprising many thousands of atoms. We describe some of the early applications of large-scale DFT to the computation of the electronic properties and structure of biomolecules, as well as to paradigmatic problems in enzymology, metalloproteins, photosynthesis and computer-aided drug design. With this review, we hope to demonstrate that first principles modelling of biological structure-function relationships are approaching a reality.

  13. The CLASSgal code for relativistic cosmological large scale structure

    SciTech Connect

    Dio, Enea Di; Montanari, Francesco; Durrer, Ruth; Lesgourgues, Julien E-mail: Francesco.Montanari@unige.ch E-mail: Ruth.Durrer@unige.ch

    2013-11-01

    We present accurate and efficient computations of large scale structure observables, obtained with a modified version of the CLASS code which is made publicly available. This code includes all relativistic corrections and computes both the power spectrum C{sub ℓ}(z{sub 1},z{sub 2}) and the corresponding correlation function ξ(θ,z{sub 1},z{sub 2}) of the matter density and the galaxy number fluctuations in linear perturbation theory. For Gaussian initial perturbations, these quantities contain the full information encoded in the large scale matter distribution at the level of linear perturbation theory. We illustrate the usefulness of our code for cosmological parameter estimation through a few simple examples.

  14. Measurement of Two-Plasmon-Decay Dependence on Plasma Density Scale Length

    NASA Astrophysics Data System (ADS)

    Haberberger, D.

    2013-10-01

    An accurate understanding of the plasma scale-length (Lq) conditions near quarter-critical density is important in quantifying the hot electrons generated by the two-plasmon-decay (TPD) instability in long-scale-length plasmas. A novel target platform was developed to vary the density scale length and an innovative diagnostic was implemented to measure the density profiles above 1021 cm-3 where TPD is expected to have the largest growth. A series of experiments was performed using the four UV (351-nm) beams on OMEGA EP that varied the Lq by changing the radius of curvature of the target while maintaining a constant Iq/Tq. The fraction of laser energy converted to hot electrons (fhot) was observed to increase rapidly from 0.005% to 1% by increasing the plasma scale length from 130 μm to 300 μm, corresponding to target diameters of 0.4 mm to 8 mm. A new diagnostic was developed based on refractometry using angular spectral filters to overcome the large phase accumulation in standard interferometric techniques. The angular filter refractometer measures the refraction angles of a 10-ps, 263-nm probe laser after propagating through the plasma. An angular spectral filter is used in the Fourier plane of the probe beam, where the refractive angles of the rays are mapped to space. The edges of the filter are present in the image plane and represent contours of constant refraction angle. These contours are used to infer the phase of the probe beam, which are used to calculate the plasma density profile. In long-scale-length plasmas, the diagnostic currently measures plasma densities from ~1019 cm-3 to ~2 × 1021 cm-3. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. In collaboration with D. H. Edgell, S. X. Hu, S. Ivancic, R. Boni, C. Dorrer, and D. H. Froula (Laboratory for Laser Energetics, U. of Rochester).

  15. Large-scale interaction of the solar wind with comets Halley and Giacobini-Zinner

    NASA Technical Reports Server (NTRS)

    Brandt, John C.; Niedner, Malcolm B., Jr.

    1987-01-01

    In-situ measurements of comets Halley and Giacobini-Zinner have confirmed the accepted basic physics of comet/solar wind interaction. The solar wind magnetic field is captured by the comet through the mechanism of field-line loading by cometary ions and the field lines drape around the cometary ionosphere. With this basic model in hand, the large-scale structure of the plasma tail as revealed by submissions to the Large Scale Phenomena Network of the International Halley Watch is reviewed. The turn-on and turn-off of plasma activity seem consistent with theory. Some 16 obvious disconnection events (DEs) have been recorded. Preliminary results showed agreement with the sector-boundary model; a detailed analysis of all DEs will be required in order to make a definitive statement. A study of plasma activity around the time of the VEGA encounters provides strong support for the sector-boundary model and illustrates once again the power of simultaneous remote and in-situ measurements.

  16. Stability of large scale chromomagnetic fields in the early universe

    NASA Astrophysics Data System (ADS)

    Elmfors, Per; Persson, David

    1999-01-01

    It is well known that Yang-Mills theory in vacuum has a perturbative instability to spontaneously form a large scale magnetic field (the Savvidy mechanism) and that a constant field is unstable so that a possible ground state has to be inhomogenous over the non-perturbative scale Λ (the Copenhagen vacuum). We argue that this spontaneous instability does not occur at high temperature when the induced field strength gB~Λ2 is much weaker than the magnetic mass squared (g2T)2. At high temperature, oscillations of gauge fields acquire a thermal mass M~gT and we show that this mass stabilizes a magnetic field which is constant over length scales shorter than the magnetic screening length (g2T)-1. We therefore conclude that there is no indication for any spontaneous generation of weak non-abelian magnetic fields in the early universe.

  17. Tools for Large-Scale Mobile Malware Analysis

    SciTech Connect

    Bierma, Michael

    2014-01-01

    Analyzing mobile applications for malicious behavior is an important area of re- search, and is made di cult, in part, by the increasingly large number of appli- cations available for the major operating systems. There are currently over 1.2 million apps available in both the Google Play and Apple App stores (the respec- tive o cial marketplaces for the Android and iOS operating systems)[1, 2]. Our research provides two large-scale analysis tools to aid in the detection and analysis of mobile malware. The rst tool we present, Andlantis, is a scalable dynamic analysis system capa- ble of processing over 3000 Android applications per hour. Traditionally, Android dynamic analysis techniques have been relatively limited in scale due to the compu- tational resources required to emulate the full Android system to achieve accurate execution. Andlantis is the most scalable Android dynamic analysis framework to date, and is able to collect valuable forensic data, which helps reverse-engineers and malware researchers identify and understand anomalous application behavior. We discuss the results of running 1261 malware samples through the system, and provide examples of malware analysis performed with the resulting data. While techniques exist to perform static analysis on a large number of appli- cations, large-scale analysis of iOS applications has been relatively small scale due to the closed nature of the iOS ecosystem, and the di culty of acquiring appli- cations for analysis. The second tool we present, iClone, addresses the challenges associated with iOS research in order to detect application clones within a dataset of over 20,000 iOS applications.

  18. Electrochemical cells for medium- and large-scale energy storage

    SciTech Connect

    Wang, Wei; Wei, Xiaoliang; Choi, Daiwon; Lu, Xiaochuan; Yang, G.; Sun, C.

    2014-12-12

    This is one of the chapters in the book titled “Advances in batteries for large- and medium-scale energy storage: Applications in power systems and electric vehicles” that will be published by the Woodhead Publishing Limited. The chapter discusses the basic electrochemical fundamentals of electrochemical energy storage devices with a focus on the rechargeable batteries. Several practical secondary battery systems are also discussed as examples

  19. Health-Terrain: Visualizing Large Scale Health Data

    DTIC Science & Technology

    2015-04-01

    Award Number: W81XWH-13-1-0020 TITLE: Health-Terrain: Visualizing Large Scale Health Data PRINCIPAL INVESTIGATOR: Ph.D. Fang, Shiaofen...ADDRESS. 1. REPORT DATE April 2015 2. REPORT TYPE Annual 3. DATES COVERED 7 MAR 2014 – 6 MAR 2015 4. TITLE AND SUBTITLE Health-Terrain: Visualizing ...1) creating a concept space data model, which represents a schema tailored to support diverse visualizations and provides a uniform ontology that

  20. A Holistic Management Architecture for Large-Scale Adaptive Networks

    DTIC Science & Technology

    2007-09-01

    MANAGEMENT ARCHITECTURE FOR LARGE-SCALE ADAPTIVE NETWORKS by Michael R. Clement September 2007 Thesis Advisor: Alex Bordetsky Second Reader...TECHNOLOGY MANAGEMENT from the NAVAL POSTGRADUATE SCHOOL September 2007 Author: Michael R. Clement Approved by: Dr. Alex ...achieve in life is by His will. Ad Majorem Dei Gloriam. To my parents, my family, and Caitlin: For supporting me, listening to me when I got

  1. Large-scale detection of recombination in nucleotide sequences

    NASA Astrophysics Data System (ADS)

    Chan, Cheong Xin; Beiko, Robert G.; Ragan, Mark A.

    2008-01-01

    Genetic recombination following a genetic transfer event can produce heterogeneous phylogenetic histories within sets of genes that share a common ancestral origin. Delineating recombination events will enhance our understanding in genome evolution. However, the task of detecting recombination is not trivial due to effect of more-recent evolutionary changes that can obscure such event from detection. In this paper, we demonstrate the use of a two-phase strategy for detecting recombination events on a large-scale dataset.

  2. Multimodel Design of Large Scale Systems with Multiple Decision Makers.

    DTIC Science & Technology

    1982-08-01

    virtue. 5- , Lead me from darkneu to light. - Lead me from death to eternal Life. ( Vedic Payer) p. I, MULTIMODEL DESIGN OF LARGE SCALE SYSTEMS WITH...guidance during the course of *: this research . He would also like to thank Professors W. R. Perkins, P. V. Kokotovic, T. Basar, and T. N. Trick for...thesis concludes with Chapter 7 where we summarize the results obtained, outline the main contributions, and indicate directions for future research . 7- I

  3. Relic vector field and CMB large scale anomalies

    SciTech Connect

    Chen, Xingang; Wang, Yi E-mail: yw366@cam.ac.uk

    2014-10-01

    We study the most general effects of relic vector fields on the inflationary background and density perturbations. Such effects are observable if the number of inflationary e-folds is close to the minimum requirement to solve the horizon problem. We show that this can potentially explain two CMB large scale anomalies: the quadrupole-octopole alignment and the quadrupole power suppression. We discuss its effect on the parity anomaly. We also provide analytical template for more detailed data comparison.

  4. The large-scale anisotropy with the PAMELA calorimeter

    NASA Astrophysics Data System (ADS)

    Karelin, A.; Adriani, O.; Barbarino, G.; Bazilevskaya, G.; Bellotti, R.; Boezio, M.; Bogomolov, E.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carbone, R.; Carlson, P.; Casolino, M.; Castellini, G.; De Donato, C.; De Santis, C.; De Simone, N.; Di Felice, V.; Formato, V.; Galper, A.; Koldashov, S.; Koldobskiy, S.; Krut'kov, S.; Kvashnin, A.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A.; Menn, W.; Mergé, M.; Mikhailov, V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S.; Sarkar, R.; Simon, M.; Scotti, V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y.; Vacchi, A.; Vannuccini, E.; Vasilyev, G.; Voronov, S.; Yurkin, Y.; Zampa, G.; Zampa, N.

    2015-10-01

    The large-scale anisotropy (or the so-called star-diurnal wave) has been studied using the calorimeter of the space-born experiment PAMELA. The cosmic ray anisotropy has been obtained for the Southern and Northern hemispheres simultaneously in the equatorial coordinate system for the time period 2006-2014. The dipole amplitude and phase have been measured for energies 1-20 TeV n-1.

  5. Large Scale Density Estimation of Blue and Fin Whales (LSD)

    DTIC Science & Technology

    2014-09-30

    interactions with human activity requires knowledge of how many animals are present in an area during a specific time period. Many marine mammal species...assumptions about animal distribution around the sensors, or both. The goal of this research is to develop and implement a new method for...estimating blue and fin whale density that is effective over large spatial scales and is designed to cope with spatial variation in animal density utilizing

  6. Supporting large scale applications on networks of workstations

    NASA Technical Reports Server (NTRS)

    Cooper, Robert; Birman, Kenneth P.

    1989-01-01

    Distributed applications on networks of workstations are an increasingly common way to satisfy computing needs. However, existing mechanisms for distributed programming exhibit poor performance and reliability as application size increases. Extension of the ISIS distributed programming system to support large scale distributed applications by providing hierarchical process groups is discussed. Incorporation of hierarchy in the program structure and exploitation of this to limit the communication and storage required in any one component of the distributed system is examined.

  7. Improving Design Efficiency for Large-Scale Heterogeneous Circuits

    NASA Astrophysics Data System (ADS)

    Gregerson, Anthony

    Despite increases in logic density, many Big Data applications must still be partitioned across multiple computing devices in order to meet their strict performance requirements. Among the most demanding of these applications is high-energy physics (HEP), which uses complex computing systems consisting of thousands of FPGAs and ASICs to process the sensor data created by experiments at particles accelerators such as the Large Hadron Collider (LHC). Designing such computing systems is challenging due to the scale of the systems, the exceptionally high-throughput and low-latency performance constraints that necessitate application-specific hardware implementations, the requirement that algorithms are efficiently partitioned across many devices, and the possible need to update the implemented algorithms during the lifetime of the system. In this work, we describe our research to develop flexible architectures for implementing such large-scale circuits on FPGAs. In particular, this work is motivated by (but not limited in scope to) high-energy physics algorithms for the Compact Muon Solenoid (CMS) experiment at the LHC. To make efficient use of logic resources in multi-FPGA systems, we introduce Multi-Personality Partitioning, a novel form of the graph partitioning problem, and present partitioning algorithms that can significantly improve resource utilization on heterogeneous devices while also reducing inter-chip connections. To reduce the high communication costs of Big Data applications, we also introduce Information-Aware Partitioning, a partitioning method that analyzes the data content of application-specific circuits, characterizes their entropy, and selects circuit partitions that enable efficient compression of data between chips. We employ our information-aware partitioning method to improve the performance of the hardware validation platform for evaluating new algorithms for the CMS experiment. Together, these research efforts help to improve the efficiency

  8. Information Tailoring Enhancements for Large Scale Social Data

    DTIC Science & Technology

    2016-03-15

    Social Data Progress Report No. 2 Reporting Period: December 16, 2015 – March 15, 2016 Contract No. N00014-15-P-5138 Sponsored by ONR...Intelligent Automation Incorporated Progress Report No. 2 Information Tailoring Enhancements for Large-Scale Social Data Submitted in accordance with...robustness. We imporoved the (i) messaging architecture, (ii) data redundancy, and (iii) service availability of Scraawl computational framework

  9. Host Immunity via Mutable Virtualized Large-Scale Network Containers

    DTIC Science & Technology

    2016-07-25

    system for host immunity that combines virtualization , emulation, and mutable network configurations. This system is deployed on a single host, and...entire !Pv4 address space within 5 Host Immunity via Mutable Virtualized Large-Scale Network Containers 45 minutes from a single machine. Second, when...URL, and we call it URL marker. A URL marker records the information about its parent web page’s URL and the user ID who collects the URL. Thus, when

  10. Concurrent Programming Using Actors: Exploiting Large-Scale Parallelism,

    DTIC Science & Technology

    1985-10-07

    ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK* Artificial Inteligence Laboratory AREA Is WORK UNIT NUMBERS 545 Technology Square...D-R162 422 CONCURRENT PROGRMMIZNG USING f"OS XL?ITP TEH l’ LARGE-SCALE PARALLELISH(U) NASI AC E Al CAMBRIDGE ARTIFICIAL INTELLIGENCE L. G AGHA ET AL...RESOLUTION TEST CHART N~ATIONAL BUREAU OF STANDA.RDS - -96 A -E. __ _ __ __’ .,*- - -- •. - MASSACHUSETTS INSTITUTE OF TECHNOLOGY ARTIFICIAL

  11. An economy of scale system's mensuration of large spacecraft

    NASA Technical Reports Server (NTRS)

    Deryder, L. J.

    1981-01-01

    The systems technology and cost particulars of using multipurpose platforms versus several sizes of bus type free flyer spacecraft to accomplish the same space experiment missions. Computer models of these spacecraft bus designs were created to obtain data relative to size, weight, power, performance, and cost. To answer the question of whether or not large scale does produce economy, the dominant cost factors were determined and the programmatic effect on individual experiment costs were evaluated.

  12. Developing and Understanding Methods for Large Scale Nonlinear Optimization

    DTIC Science & Technology

    2001-12-01

    development of new algorithms for large-scale uncon- strained and constrained optimization problems, including limited-memory methods for problems with...analysis of tensor and SQP methods for singular con- strained optimization", to appear in SIAM Journal on Optimization. Published in peer-reviewed...Mathematica, Vol III, Journal der Deutschen Mathematiker-Vereinigung, 1998. S. Crivelli, B. Bader, R. Byrd, E. Eskow, V. Lamberti , R.Schnabel and T

  13. Analysis plan for 1985 large-scale tests. Technical report

    SciTech Connect

    McMullan, F.W.

    1983-01-01

    The purpose of this effort is to assist DNA in planning for large-scale (upwards of 5000 tons) detonations of conventional explosives in the 1985 and beyond time frame. Primary research objectives were to investigate potential means to increase blast duration and peak pressures. This report identifies and analyzes several candidate explosives. It examines several charge designs and identifies advantages and disadvantages of each. Other factors including terrain and multiburst techniques are addressed as are test site considerations.

  14. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

    NASA Technical Reports Server (NTRS)

    Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dunner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.

    2015-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe approx.70% of the sky. A variable-delay polarization modulator provides modulation of the polarization at approx.10Hz to suppress the 1/f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.

  15. High Speed Networking and Large-scale Simulation in Geodynamics

    NASA Technical Reports Server (NTRS)

    Kuang, Weijia; Gary, Patrick; Seablom, Michael; Truszkowski, Walt; Odubiyi, Jide; Jiang, Weiyuan; Liu, Dong

    2004-01-01

    Large-scale numerical simulation has been one of the most important approaches for understanding global geodynamical processes. In this approach, peta-scale floating point operations (pflops) are often required to carry out a single physically-meaningful numerical experiment. For example, to model convective flow in the Earth's core and generation of the geomagnetic field (geodynamo), simulation for one magnetic free-decay time (approximately 15000 years) with a modest resolution of 150 in three spatial dimensions would require approximately 0.2 pflops. If such a numerical model is used to predict geomagnetic secular variation over decades and longer, with e.g. an ensemble Kalman filter assimilation approach, approximately 30 (and perhaps more) independent simulations of similar scales would be needed for one data assimilation analysis. Obviously, such a simulation would require an enormous computing resource that exceeds the capacity of a single facility currently available at our disposal. One solution is to utilize a very fast network (e.g. 10Gb optical networks) and available middleware (e.g. Globus Toolkit) to allocate available but often heterogeneous resources for such large-scale computing efforts. At NASA GSFC, we are experimenting with such an approach by networking several clusters for geomagnetic data assimilation research. We shall present our initial testing results in the meeting.

  16. Domain nesting for multi-scale large eddy simulation

    NASA Astrophysics Data System (ADS)

    Fuka, Vladimir; Xie, Zheng-Tong

    2016-04-01

    The need to simulate city scale areas (O(10 km)) with high resolution within street canyons in certain areas of interests necessitates different grid resolutions in different part of the simulated area. General purpose computational fluid dynamics codes typically employ unstructured refined grids while mesoscale meteorological models more often employ nesting of computational domains. ELMM is a large eddy simulation model for the atmospheric boundary layer. It employs orthogonal uniform grids and for this reason domain nesting was chosen as the approach for simulations in multiple scales. Domains are implemented as sets of MPI processes which communicate with each other as in a normal non-nested run, but also with processes from another (outer/inner) domain. It should stressed that the duration of solution of time-steps in the outer and in the inner domain must be synchronized, so that the processes do not have to wait for the completion of their boundary conditions. This can achieved by assigning an appropriate number of CPUs to each domain, and to gain high efficiency. When nesting is applied for large eddy simulation, the inner domain receives inflow boundary conditions which lack turbulent motions not represented by the outer grid. ELMM remedies this by optional adding of turbulent fluctuations to the inflow using the efficient method of Xie and Castro (2008). The spatial scale of these fluctuations is in the subgrid-scale of the outer grid and their intensity will be estimated from the subgrid turbulent kinetic energy in the outer grid.

  17. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

    NASA Astrophysics Data System (ADS)

    Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dünner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-Yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.

    2016-08-01

    The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe ˜ 70 % of the sky. A variable-delay polarization modulator provides modulation of the polarization at ˜ 10 Hz to suppress the 1/ f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.

  18. Equivalent common path method in large-scale laser comparator

    NASA Astrophysics Data System (ADS)

    He, Mingzhao; Li, Jianshuang; Miao, Dongjing

    2015-02-01

    Large-scale laser comparator is main standard device that providing accurate, reliable and traceable measurements for high precision large-scale line and 3D measurement instruments. It mainly composed of guide rail, motion control system, environmental parameters monitoring system and displacement measurement system. In the laser comparator, the main error sources are temperature distribution, straightness of guide rail and pitch and yaw of measuring carriage. To minimize the measurement uncertainty, an equivalent common optical path scheme is proposed and implemented. Three laser interferometers are adjusted to parallel with the guide rail. The displacement in an arbitrary virtual optical path is calculated using three displacements without the knowledge of carriage orientations at start and end positions. The orientation of air floating carriage is calculated with displacements of three optical path and position of three retroreflectors which are precisely measured by Laser Tracker. A 4th laser interferometer is used in the virtual optical path as reference to verify this compensation method. This paper analyzes the effect of rail straightness on the displacement measurement. The proposed method, through experimental verification, can improve the measurement uncertainty of large-scale laser comparator.

  19. Dispersal Mutualism Incorporated into Large-Scale, Infrequent Disturbances

    PubMed Central

    Parker, V. Thomas

    2015-01-01

    Because of their influence on succession and other community interactions, large-scale, infrequent natural disturbances also should play a major role in mutualistic interactions. Using field data and experiments, I test whether mutualisms have been incorporated into large-scale wildfire by whether the outcomes of a mutualism depend on disturbance. In this study a seed dispersal mutualism is shown to depend on infrequent, large-scale disturbances. A dominant shrubland plant (Arctostaphylos species) produces seeds that make up a persistent soil seed bank and requires fire to germinate. In post-fire stands, I show that seedlings emerging from rodent caches dominate sites experiencing higher fire intensity. Field experiments show that rodents (Perimyscus californicus, P. boylii) do cache Arctostaphylos fruit and bury most seed caches to a sufficient depth to survive a killing heat pulse that a fire might drive into the soil. While the rodent dispersal and caching behavior itself has not changed compared to other habitats, the environmental transformation caused by wildfire converts the caching burial of seed from a dispersal process to a plant fire adaptive trait, and provides the context for stimulating subsequent life history evolution in the plant host. PMID:26151560

  20. Power suppression at large scales in string inflation

    SciTech Connect

    Cicoli, Michele; Downes, Sean; Dutta, Bhaskar E-mail: sddownes@physics.tamu.edu

    2013-12-01

    We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters.

  1. An Emerging Infectious Disease Triggering Large-Scale Hyperpredation

    PubMed Central

    Moleón, Marcos; Almaraz, Pablo; Sánchez-Zapata, José A.

    2008-01-01

    Hyperpredation refers to an enhanced predation pressure on a secondary prey due to either an increase in the abundance of a predator population or a sudden drop in the abundance of the main prey. This scarcely documented mechanism has been previously studied in scenarios in which the introduction of a feral prey caused overexploitation of native prey. Here we provide evidence of a previously unreported link between Emergent Infectious Diseases (EIDs) and hyperpredation on a predator-prey community. We show how a viral outbreak caused the population collapse of a host prey at a large spatial scale, which subsequently promoted higher-than-normal predation intensity on a second prey from shared predators. Thus, the disease left a population dynamic fingerprint both in the primary host prey, through direct mortality from the disease, and indirectly in the secondary prey, through hyperpredation. This resulted in synchronized prey population dynamics at a large spatio-temporal scale. We therefore provide evidence for a novel mechanism by which EIDs can disrupt a predator-prey interaction from the individual behavior to the population dynamics. This mechanism can pose a further threat to biodiversity through the human-aided disruption of ecological interactions at large spatial and temporal scales. PMID:18523587

  2. Line segment extraction for large scale unorganized point clouds

    NASA Astrophysics Data System (ADS)

    Lin, Yangbin; Wang, Cheng; Cheng, Jun; Chen, Bili; Jia, Fukai; Chen, Zhonggui; Li, Jonathan

    2015-04-01

    Line segment detection in images is already a well-investigated topic, although it has received considerably less attention in 3D point clouds. Benefiting from current LiDAR devices, large-scale point clouds are becoming increasingly common. Most human-made objects have flat surfaces. Line segments that occur where pairs of planes intersect give important information regarding the geometric content of point clouds, which is especially useful for automatic building reconstruction and segmentation. This paper proposes a novel method that is capable of accurately extracting plane intersection line segments from large-scale raw scan points. The 3D line-support region, namely, a point set near a straight linear structure, is extracted simultaneously. The 3D line-support region is fitted by our Line-Segment-Half-Planes (LSHP) structure, which provides a geometric constraint for a line segment, making the line segment more reliable and accurate. We demonstrate our method on the point clouds of large-scale, complex, real-world scenes acquired by LiDAR devices. We also demonstrate the application of 3D line-support regions and their LSHP structures on urban scene abstraction.

  3. Reliability assessment for components of large scale photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Ahadi, Amir; Ghadimi, Noradin; Mirabbasi, Davar

    2014-10-01

    Photovoltaic (PV) systems have significantly shifted from independent power generation systems to a large-scale grid-connected generation systems in recent years. The power output of PV systems is affected by the reliability of various components in the system. This study proposes an analytical approach to evaluate the reliability of large-scale, grid-connected PV systems. The fault tree method with an exponential probability distribution function is used to analyze the components of large-scale PV systems. The system is considered in the various sequential and parallel fault combinations in order to find all realistic ways in which the top or undesired events can occur. Additionally, it can identify areas that the planned maintenance should focus on. By monitoring the critical components of a PV system, it is possible not only to improve the reliability of the system, but also to optimize the maintenance costs. The latter is achieved by informing the operators about the system component's status. This approach can be used to ensure secure operation of the system by its flexibility in monitoring system applications. The implementation demonstrates that the proposed method is effective and efficient and can conveniently incorporate more system maintenance plans and diagnostic strategies.

  4. Learning Short Binary Codes for Large-scale Image Retrieval.

    PubMed

    Liu, Li; Yu, Mengyang; Shao, Ling

    2017-03-01

    Large-scale visual information retrieval has become an active research area in this big data era. Recently, hashing/binary coding algorithms prove to be effective for scalable retrieval applications. Most existing hashing methods require relatively long binary codes (i.e., over hundreds of bits, sometimes even thousands of bits) to achieve reasonable retrieval accuracies. However, for some realistic and unique applications, such as on wearable or mobile devices, only short binary codes can be used for efficient image retrieval due to the limitation of computational resources or bandwidth on these devices. In this paper, we propose a novel unsupervised hashing approach called min-cost ranking (MCR) specifically for learning powerful short binary codes (i.e., usually the code length shorter than 100 b) for scalable image retrieval tasks. By exploring the discriminative ability of each dimension of data, MCR can generate one bit binary code for each dimension and simultaneously rank the discriminative separability of each bit according to the proposed cost function. Only top-ranked bits with minimum cost-values are then selected and grouped together to compose the final salient binary codes. Extensive experimental results on large-scale retrieval demonstrate that MCR can achieve comparative performance as the state-of-the-art hashing algorithms but with significantly shorter codes, leading to much faster large-scale retrieval.

  5. Large-scale columnar vortices in rotating turbulence

    NASA Astrophysics Data System (ADS)

    Yokoyama, Naoto; Takaoka, Masanori

    2016-11-01

    In the rotating turbulence, flow structures are affected by the angular velocity of the system's rotation. When the angular velocity is small, three-dimensional statistically-isotropic flow, which has the Kolmogorov spectrum all over the inertial subrange, is formed. When the angular velocity increases, the flow becomes two-dimensional anisotropic, and the energy spectrum has a power law k-2 in the small wavenumbers in addition to the Kolmogorov spectrum in the large wavenumbers. When the angular velocity decreases, the flow returns to the isotropic one. It is numerically found that the transition between the isotropic and anisotropic flows is hysteretic; the critical angular velocity at which the flow transitions from the anisotropic one to the isotropic one, and that of the reverse transition are different. It is also observed that the large-scale columnar structures in the anisotropic flow depends on the external force which maintains a statistically-steady state. In some cases, small-scale anticyclonic structures are aligned in a columnar structure apart from the cyclonic Taylor column. The formation mechanism of the large-scale columnar structures will be discussed. This work was partially supported by JSPS KAKENHI.

  6. Large scale CMB anomalies from thawing cosmic strings

    SciTech Connect

    Ringeval, Christophe; Yamauchi, Daisuke; Yokoyama, Jun'ichi; Bouchet, François R. E-mail: yamauchi@resceu.s.u-tokyo.ac.jp E-mail: bouchet@iap.fr

    2016-02-01

    Cosmic strings formed during inflation are expected to be either diluted over super-Hubble distances, i.e., invisible today, or to have crossed our past light cone very recently. We discuss the latter situation in which a few strings imprint their signature in the Cosmic Microwave Background (CMB) Anisotropies after recombination. Being almost frozen in the Hubble flow, these strings are quasi static and evade almost all of the previously derived constraints on their tension while being able to source large scale anisotropies in the CMB sky. Using a local variance estimator on thousand of numerically simulated Nambu-Goto all sky maps, we compute the expected signal and show that it can mimic a dipole modulation at large angular scales while being negligible at small angles. Interestingly, such a scenario generically produces one cold spot from the thawing of a cosmic string loop. Mixed with anisotropies of inflationary origin, we find that a few strings of tension GU = O(1) × 10{sup −6} match the amplitude of the dipole modulation reported in the Planck satellite measurements and could be at the origin of other large scale anomalies.

  7. Origin of the large scale structures of the universe

    SciTech Connect

    Oaknin, David H.

    2004-11-15

    We revise the statistical properties of the primordial cosmological density anisotropies that, at the time of matter-radiation equality, seeded the gravitational development of large scale structures in the otherwise homogeneous and isotropic Friedmann-Robertson-Walker flat universe. Our analysis shows that random fluctuations of the density field at the same instant of equality and with comoving wavelength shorter than the causal horizon at that time can naturally account, when globally constrained to conserve the total mass (energy) of the system, for the observed scale invariance of the anisotropies over cosmologically large comoving volumes. Statistical systems with similar features are generically known as glasslike or latticelike. Obviously, these conclusions conflict with the widely accepted understanding of the primordial structures reported in the literature, which requires an epoch of inflationary cosmology to precede the standard expansion of the universe. The origin of the conflict must be found in the widespread, but unjustified, claim that scale invariant mass (energy) anisotropies at the instant of equality over comoving volumes of cosmological size, larger than the causal horizon at the time, must be generated by fluctuations in the density field with comparably large comoving wavelength.

  8. Large-scale investigation of genomic markers for severe periodontitis.

    PubMed

    Suzuki, Asami; Ji, Guijin; Numabe, Yukihiro; Ishii, Keisuke; Muramatsu, Masaaki; Kamoi, Kyuichi

    2004-09-01

    The purpose of the present study was to investigate the genomic markers for periodontitis, using large-scale single-nucleotide polymorphism (SNP) association studies comparing healthy volunteers and patients with periodontitis. Genomic DNA was obtained from 19 healthy volunteers and 22 patients with severe periodontitis, all of whom were Japanese. The subjects were genotyped at 637 SNPs in 244 genes on a large scale, using the TaqMan polymerase chain reaction (PCR) system. Statistically significant differences in allele and genotype frequencies were analyzed with Fisher's exact test. We found statistically significant differences (P < 0.01) between the healthy volunteers and patients with severe periodontitis in the following genes; gonadotropin-releasing hormone 1 (GNRH1), phosphatidylinositol 3-kinase regulatory 1 (PIK3R1), dipeptidylpeptidase 4 (DPP4), fibrinogen-like 2 (FGL2), and calcitonin receptor (CALCR). These results suggest that SNPs in the GNRH1, PIK3R1, DPP4, FGL2, and CALCR genes are genomic markers for severe periodontitis. Our findings indicate the necessity of analyzing SNPs in genes on a large scale (i.e., genome-wide approach), to identify genomic markers for periodontitis.

  9. Large-scale flow generation by inhomogeneous helicity.

    PubMed

    Yokoi, N; Brandenburg, A

    2016-03-01

    The effect of kinetic helicity (velocity-vorticity correlation) on turbulent momentum transport is investigated. The turbulent kinetic helicity (pseudoscalar) enters the Reynolds stress (mirror-symmetric tensor) expression in the form of a helicity gradient as the coupling coefficient for the mean vorticity and/or the angular velocity (axial vector), which suggests the possibility of mean-flow generation in the presence of inhomogeneous helicity. This inhomogeneous helicity effect, which was previously confirmed at the level of a turbulence- or closure-model simulation, is examined with the aid of direct numerical simulations of rotating turbulence with nonuniform helicity sustained by an external forcing. The numerical simulations show that the spatial distribution of the Reynolds stress is in agreement with the helicity-related term coupled with the angular velocity, and that a large-scale flow is generated in the direction of angular velocity. Such a large-scale flow is not induced in the case of homogeneous turbulent helicity. This result confirms the validity of the inhomogeneous helicity effect in large-scale flow generation and suggests that a vortex dynamo is possible even in incompressible turbulence where there is no baroclinicity effect.

  10. Large-scale flow experiments for managing river systems

    USGS Publications Warehouse

    Konrad, Christopher P.; Olden, Julian D.; Lytle, David A.; Melis, Theodore S.; Schmidt, John C.; Bray, Erin N.; Freeman, Mary C.; Gido, Keith B.; Hemphill, Nina P.; Kennard, Mark J.; McMullen, Laura E.; Mims, Meryl C.; Pyron, Mark; Robinson, Christopher T.; Williams, John G.

    2011-01-01

    Experimental manipulations of streamflow have been used globally in recent decades to mitigate the impacts of dam operations on river systems. Rivers are challenging subjects for experimentation, because they are open systems that cannot be isolated from their social context. We identify principles to address the challenges of conducting effective large-scale flow experiments. Flow experiments have both scientific and social value when they help to resolve specific questions about the ecological action of flow with a clear nexus to water policies and decisions. Water managers must integrate new information into operating policies for large-scale experiments to be effective. Modeling and monitoring can be integrated with experiments to analyze long-term ecological responses. Experimental design should include spatially extensive observations and well-defined, repeated treatments. Large-scale flow manipulations are only a part of dam operations that affect river systems. Scientists can ensure that experimental manipulations continue to be a valuable approach for the scientifically based management of river systems.

  11. Large scale stochastic spatio-temporal modelling with PCRaster

    NASA Astrophysics Data System (ADS)

    Karssenberg, Derek; Drost, Niels; Schmitz, Oliver; de Jong, Kor; Bierkens, Marc F. P.

    2013-04-01

    software from the eScience Technology Platform (eSTeP), developed at the Netherlands eScience Center. This will allow us to scale up to hundreds of machines, with thousands of compute cores. A key requirement is not to change the user experience of the software. PCRaster operations and the use of the Python framework classes should work in a similar manner on machines ranging from a laptop to a supercomputer. This enables a seamless transfer of models from small machines, where model development is done, to large machines used for large-scale model runs. Domain specialists from a large range of disciplines, including hydrology, ecology, sedimentology, and land use change studies, currently use the PCRaster Python software within research projects. Applications include global scale hydrological modelling and error propagation in large-scale land use change models. The software runs on MS Windows, Linux operating systems, and OS X.

  12. A new large-scale manufacturing platform for complex biopharmaceuticals.

    PubMed

    Vogel, Jens H; Nguyen, Huong; Giovannini, Roberto; Ignowski, Jolene; Garger, Steve; Salgotra, Anil; Tom, Jennifer

    2012-12-01

    Complex biopharmaceuticals, such as recombinant blood coagulation factors, are addressing critical medical needs and represent a growing multibillion-dollar market. For commercial manufacturing of such, sometimes inherently unstable, molecules it is important to minimize product residence time in non-ideal milieu in order to obtain acceptable yields and consistently high product quality. Continuous perfusion cell culture allows minimization of residence time in the bioreactor, but also brings unique challenges in product recovery, which requires innovative solutions. In order to maximize yield, process efficiency, facility and equipment utilization, we have developed, scaled-up and successfully implemented a new integrated manufacturing platform in commercial scale. This platform consists of a (semi-)continuous cell separation process based on a disposable flow path and integrated with the upstream perfusion operation, followed by membrane chromatography on large-scale adsorber capsules in rapid cycling mode. Implementation of the platform at commercial scale for a new product candidate led to a yield improvement of 40% compared to the conventional process technology, while product quality has been shown to be more consistently high. Over 1,000,000 L of cell culture harvest have been processed with 100% success rate to date, demonstrating the robustness of the new platform process in GMP manufacturing. While membrane chromatography is well established for polishing in flow-through mode, this is its first commercial-scale application for bind/elute chromatography in the biopharmaceutical industry and demonstrates its potential in particular for manufacturing of potent, low-dose biopharmaceuticals.

  13. Robust large-scale parallel nonlinear solvers for simulations.

    SciTech Connect

    Bader, Brett William; Pawlowski, Roger Patrick; Kolda, Tamara Gibson

    2005-11-01

    This report documents research to develop robust and efficient solution techniques for solving large-scale systems of nonlinear equations. The most widely used method for solving systems of nonlinear equations is Newton's method. While much research has been devoted to augmenting Newton-based solvers (usually with globalization techniques), little has been devoted to exploring the application of different models. Our research has been directed at evaluating techniques using different models than Newton's method: a lower order model, Broyden's method, and a higher order model, the tensor method. We have developed large-scale versions of each of these models and have demonstrated their use in important applications at Sandia. Broyden's method replaces the Jacobian with an approximation, allowing codes that cannot evaluate a Jacobian or have an inaccurate Jacobian to converge to a solution. Limited-memory methods, which have been successful in optimization, allow us to extend this approach to large-scale problems. We compare the robustness and efficiency of Newton's method, modified Newton's method, Jacobian-free Newton-Krylov method, and our limited-memory Broyden method. Comparisons are carried out for large-scale applications of fluid flow simulations and electronic circuit simulations. Results show that, in cases where the Jacobian was inaccurate or could not be computed, Broyden's method converged in some cases where Newton's method failed to converge. We identify conditions where Broyden's method can be more efficient than Newton's method. We also present modifications to a large-scale tensor method, originally proposed by Bouaricha, for greater efficiency, better robustness, and wider applicability. Tensor methods are an alternative to Newton-based methods and are based on computing a step based on a local quadratic model rather than a linear model. The advantage of Bouaricha's method is that it can use any existing linear solver, which makes it simple to write

  14. Foundational perspectives on causality in large-scale brain networks.

    PubMed

    Mannino, Michael; Bressler, Steven L

    2015-12-01

    A profusion of recent work in cognitive neuroscience has been concerned with the endeavor to uncover causal influences in large-scale brain networks. However, despite the fact that many papers give a nod to the important theoretical challenges posed by the concept of causality, this explosion of research has generally not been accompanied by a rigorous conceptual analysis of the nature of causality in the brain. This review provides both a descriptive and prescriptive account of the nature of causality as found within and between large-scale brain networks. In short, it seeks to clarify the concept of causality in large-scale brain networks both philosophically and scientifically. This is accomplished by briefly reviewing the rich philosophical history of work on causality, especially focusing on contributions by David Hume, Immanuel Kant, Bertrand Russell, and Christopher Hitchcock. We go on to discuss the impact that various interpretations of modern physics have had on our understanding of causality. Throughout all this, a central focus is the distinction between theories of deterministic causality (DC), whereby causes uniquely determine their effects, and probabilistic causality (PC), whereby causes change the probability of occurrence of their effects. We argue that, given the topological complexity of its large-scale connectivity, the brain should be considered as a complex system and its causal influences treated as probabilistic in nature. We conclude that PC is well suited for explaining causality in the brain for three reasons: (1) brain causality is often mutual; (2) connectional convergence dictates that only rarely is the activity of one neuronal population uniquely determined by another one; and (3) the causal influences exerted between neuronal populations may not have observable effects. A number of different techniques are currently available to characterize causal influence in the brain. Typically, these techniques quantify the statistical

  15. Foundational perspectives on causality in large-scale brain networks

    NASA Astrophysics Data System (ADS)

    Mannino, Michael; Bressler, Steven L.

    2015-12-01

    A profusion of recent work in cognitive neuroscience has been concerned with the endeavor to uncover causal influences in large-scale brain networks. However, despite the fact that many papers give a nod to the important theoretical challenges posed by the concept of causality, this explosion of research has generally not been accompanied by a rigorous conceptual analysis of the nature of causality in the brain. This review provides both a descriptive and prescriptive account of the nature of causality as found within and between large-scale brain networks. In short, it seeks to clarify the concept of causality in large-scale brain networks both philosophically and scientifically. This is accomplished by briefly reviewing the rich philosophical history of work on causality, especially focusing on contributions by David Hume, Immanuel Kant, Bertrand Russell, and Christopher Hitchcock. We go on to discuss the impact that various interpretations of modern physics have had on our understanding of causality. Throughout all this, a central focus is the distinction between theories of deterministic causality (DC), whereby causes uniquely determine their effects, and probabilistic causality (PC), whereby causes change the probability of occurrence of their effects. We argue that, given the topological complexity of its large-scale connectivity, the brain should be considered as a complex system and its causal influences treated as probabilistic in nature. We conclude that PC is well suited for explaining causality in the brain for three reasons: (1) brain causality is often mutual; (2) connectional convergence dictates that only rarely is the activity of one neuronal population uniquely determined by another one; and (3) the causal influences exerted between neuronal populations may not have observable effects. A number of different techniques are currently available to characterize causal influence in the brain. Typically, these techniques quantify the statistical

  16. The Impact of Large Scale Environments on Cluster Entropy Profiles

    NASA Astrophysics Data System (ADS)

    Trierweiler, Isabella; Su, Yuanyuan

    2017-01-01

    We perform a systematic analysis of 21 clusters imaged by the Suzaku satellite to determine the relation between the richness of cluster environments and entropy at large radii. Entropy profiles for clusters are expected to follow a power-law, but Suzaku observations show that the entropy profiles of many clusters are significantly flattened beyond 0.3 Rvir. While the entropy at the outskirts of clusters is thought to be highly dependent on the large scale cluster environment, the exact nature of the environment/entropy relation is unclear. Using the Sloan Digital Sky Survey and 6dF Galaxy Survey, we study the 20 Mpc large scale environment for all clusters in our sample. We find no strong relation between the entropy deviations at the virial radius and the total luminosity of the cluster surroundings, indicating that accretion and mergers have a more complex and indirect influence on the properties of the gas at large radii. We see a possible anti-correlation between virial temperature and richness of the cluster environment and find that density excess appears to play a larger role in the entropy flattening than temperature, suggesting that clumps of gas can lower entropy.

  17. The effect of large-scale tropospheric storms on the ionospheres of giant planets

    NASA Astrophysics Data System (ADS)

    Matcheva, Katia

    2015-11-01

    It is well recognized that large-scale storms in the Earth troposphere can leave observable signatures in the structure of the ionosphere in terms of local electron density distribution. Terrestrial numerical models indicate that thunderstorms can change the electron density by more than an order of magnitude (Shao et al. 2012). The atmospheres of Jupiter and Saturn are riddled by atmospheric storms of all scales. Lightning has been successfully detected in optical images in the tropospheres of both planets. Our work presents a theoretical study of the dynamical and electromagnetic effects of large thunderstorms on the vertical plasma distribution in the ionospheres of Jupiter and Saturn and compares the predicted signatures with the available electron density profiles from the Galileo and the Cassini missions.

  18. Nuclear-pumped lasers for large-scale applications

    SciTech Connect

    Anderson, R.E.; Leonard, E.M.; Shea, R.E.; Berggren, R.R.

    1988-01-01

    Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficient short initiation pulse may be possible. Proof-of-principle experiments are planned to demonstrate lasing in a direct nuclear-pumped large-volume system: to study the effects of various neutron absorbing materials on laser performance; to study the effects of long initiation pulse lengths; to determine the performance of large-scale optics and the beam quality that may bo obtained; and to assess the performance of alternative designs of burst systems that increase the neutron output and burst repetition rate. 21 refs., 7 figs., 5 tabs.

  19. Self-* and Adaptive Mechanisms for Large Scale Distributed Systems

    NASA Astrophysics Data System (ADS)

    Fragopoulou, P.; Mastroianni, C.; Montero, R.; Andrjezak, A.; Kondo, D.

    Large-scale distributed computing systems and infrastructure, such as Grids, P2P systems and desktop Grid platforms, are decentralized, pervasive, and composed of a large number of autonomous entities. The complexity of these systems is such that human administration is nearly impossible and centralized or hierarchical control is highly inefficient. These systems need to run on highly dynamic environments, where content, network topologies and workloads are continuously changing. Moreover, they are characterized by the high degree of volatility of their components and the need to provide efficient service management and to handle efficiently large amounts of data. This paper describes some of the areas for which adaptation emerges as a key feature, namely, the management of computational Grids, the self-management of desktop Grid platforms and the monitoring and healing of complex applications. It also elaborates on the use of bio-inspired algorithms to achieve self-management. Related future trends and challenges are described.

  20. Turbulence and entrainment length scales in large wind farms.

    PubMed

    Andersen, Søren J; Sørensen, Jens N; Mikkelsen, Robert F

    2017-04-13

    A number of large wind farms are modelled using large eddy simulations to elucidate the entrainment process. A reference simulation without turbines and three farm simulations with different degrees of imposed atmospheric turbulence are presented. The entrainment process is assessed using proper orthogonal decomposition, which is employed to detect the largest and most energetic coherent turbulent structures. The dominant length scales responsible for the entrainment process are shown to grow further into the wind farm, but to be limited in extent by the streamwise turbine spacing, which could be taken into account when developing farm layouts. The self-organized motion or large coherent structures also yield high correlations between the power productions of consecutive turbines, which can be exploited through dynamic farm control.This article is part of the themed issue 'Wind energy in complex terrains'.

  1. Drive of parallel flows by turbulence and large-scale E × B transverse transport in divertor geometry

    NASA Astrophysics Data System (ADS)

    Galassi, D.; Tamain, P.; Bufferand, H.; Ciraolo, G.; Ghendrih, Ph.; Baudoin, C.; Colin, C.; Fedorczak, N.; Nace, N.; Serre, E.

    2017-03-01

    The poloidal asymmetries of parallel flows in edge plasmas are investigated by the 3D fluid turbulence code TOKAM3X. A diverted COMPASS-like magnetic equilibrium is used for the simulations. The measurements and simulations of parallel Mach numbers are compared, and exhibit good qualitative agreement. Small-scale turbulent transport is observed to dominate near the low field side midplane, even though it co-exists with significant large-scale cross-field fluxes. Despite the turbulent nature of the plasma in the divertor region, simulations show the low effectiveness of turbulence for the cross-field transport towards the private flux region. Nevertheless, a complex pattern of fluxes associated with the average field components are found to cross the separatrix in the divertor region. Large-scale and small-scale turbulent E× B transport, along with the \

  2. 75 FR 51843 - In the Matter of Certain Large Scale Integrated Circuit Semiconductor Chips and Products...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... Matter of Certain Large Scale Integrated Circuit Semiconductor Chips and Products Containing the Same... certain large scale integrated circuit semiconductor chips and products containing same by reason...

  3. LARGE-SCALE CO2 TRANSPORTATION AND DEEP OCEAN SEQUESTRATION

    SciTech Connect

    Hamid Sarv

    1999-03-01

    Technical and economical feasibility of large-scale CO{sub 2} transportation and ocean sequestration at depths of 3000 meters or grater was investigated. Two options were examined for transporting and disposing the captured CO{sub 2}. In one case, CO{sub 2} was pumped from a land-based collection center through long pipelines laid on the ocean floor. Another case considered oceanic tanker transport of liquid carbon dioxide to an offshore floating structure for vertical injection to the ocean floor. In the latter case, a novel concept based on subsurface towing of a 3000-meter pipe, and attaching it to the offshore structure was considered. Budgetary cost estimates indicate that for distances greater than 400 km, tanker transportation and offshore injection through a 3000-meter vertical pipe provides the best method for delivering liquid CO{sub 2} to deep ocean floor depressions. For shorter distances, CO{sub 2} delivery by parallel-laid, subsea pipelines is more cost-effective. Estimated costs for 500-km transport and storage at a depth of 3000 meters by subsea pipelines and tankers were 1.5 and 1.4 dollars per ton of stored CO{sub 2}, respectively. At these prices, economics of ocean disposal are highly favorable. Future work should focus on addressing technical issues that are critical to the deployment of a large-scale CO{sub 2} transportation and disposal system. Pipe corrosion, structural design of the transport pipe, and dispersion characteristics of sinking CO{sub 2} effluent plumes have been identified as areas that require further attention. Our planned activities in the next Phase include laboratory-scale corrosion testing, structural analysis of the pipeline, analytical and experimental simulations of CO{sub 2} discharge and dispersion, and the conceptual economic and engineering evaluation of large-scale implementation.

  4. Large and small color differences: predicting them from hue scaling

    NASA Astrophysics Data System (ADS)

    Chan, Hoover; Abramov, Israel; Gordon, James

    1991-06-01

    Color appearance can be specified by a procedure of direct hue scaling. In this procedure, subjects look at a stimulus and then simply state the proportions of their sensations using the four unique hue names red, yellow, green, and blue; to completeness, they also state the apparent saturation. Observers can scale stimuli quickly and reliably, and this is true even if they are relatively inexperienced. Thus stimuli can be rescaled whenever viewing conditions change such that a new specification of appearance is required. The scaled sensory values elicited by a set of stimuli are used to derive the locations of the stimuli on a color diagram that is based on appearance and which we term a Uniform Appearance Diagram (UAD). The orthogonal axes of these space are red-green and yellow-blue; the location of a stimulus specifies its hue and its distance from the origin specifies its apparent saturation. We have investigated the uniformity of this space by using a subject's UAD, for a particular set of viewing conditions, to predict both small and large color differences under comparable viewing conditions. For small-scale differences we compared wavelength discrimination functions derived from UADs with those obtained by direct adjustment of a bipartite field. For large-scale differences, subjects rated the degree of similarity of pairs of different wavelengths; these ratings were compared with the distances separating the same pairs of wavelengths on a UAD. In both cases, the agreements were very good, implying that UAD's are metrically uniform. Thus, UADs could be used to adjust the hues in a pseudo-color display so that all transitions would be equally perceptible or would differ by specified amounts.

  5. Large- and Small-Scale Ring Current Electrodynamic Coupling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2003-01-01

    In this talk we will address the two primary issues of ring current (RC) electrodynamic coupling: 1. RC self-consistent magnetosphere-ionosphere coupling that includes calculation of the magnetospheric electric field (large scale electrodynamic coupling); and 2. RC self-consistent coupling with electromagnetic ion cyclotron (EMIC) waves (small scale electrodynamic coupling). Our study will be based on two RC models that we have recently developed in our group. The first model by Khazanov et al. [2002] couples the system of two kinetic equations: one equation which describes the RC ion dynamics and another equation which describes the energy density evolution of EMIC waves. The second model by Khazanov et al. [2003] deals with large scale electrodynamic coupling processes and provides a self-consistent simulation of RC ions and the magnetospheric electric field. There is presently no model that addresses both of these issues simultaneously in a self-consistent calculation. However, the need exists for such a model, because these two processes directly influence each other, with the mesoscale coupling changing the drift paths of the thermal and energetic particle populations in the inner magnetosphere, thereby changing the wave interactions, and the microscale coupling altering the pitch angle distributions and ionospheric conductivities (through increased precipitation), thus changing the field-aligned currents and electric potential structure. The initial thrust of the work will be the development of a combined kinetic model of micro- and meso-scale RC electrodynamic coupling processes and to examine their interactions with each other on a global scale.

  6. Large Scale CW ECRH Systems: Meeting a Challenge

    SciTech Connect

    Erckmann, V.; Braune, H.; Laqua, H. P.; Marushchenko, N. B.; Michel, G.; Kasparek, W.; Plaum, B.; Lechte, C.; Stuttgart, IPF; Petelin, M. I.; Lubiako, L.; Bruschi, A.; D'Arcangelo, O.; Bin, W.; Van Den Braber, R.; Doelman, N.; Gantenbein, G.; Thumm, M.

    2011-12-23

    Electron Cyclotron Resonance Heating (ECRH) systems for next step-fusion devices like W7-X and ITER operate in CW-mode and provide a large flexibility to comply with various physics demands such as plasma start-up, heating and current drive, as well as configuration and MHD control. The request for many different sophisticated applications results in a growing complexity of the systems. This is in conflict with the request for high availability, reliability, and maintainability, which arises from DEMO demands. 'Advanced' ECRH-components must, therefore, comply with both the complex physics demands and operational robustness and reliability. The W7-X ECRH system is the first CW facility of an ITER relevant size and is used as a test bed for such components. Results on improvements of gyrotrons, transmission components and launchers are presented together with proposals for future developments.

  7. Small-Scale Variability of Large Cloud Drops

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Knyazikhin, Y.; Wiscombe, Warren

    2004-01-01

    Cloud droplet size distribution is one of the most fundamental subjects in cloud physics. Understanding of spatial distribution and small-scale fluctuations of cloud droplets is essential for both cloud physics and atmospheric radiation. For cloud physics, it relates to the coalescence growth of raindrops while for radiation, it has a strong impact on a cloud's radiative properties. Most of the existing cloud radiation and precipitation formation models assume that the mean number of drops with a given radius varies proportionally to volume. The analysis of microphysical data on liquid water drop sizes shows that, for sufficiently small volumes, the number is proportional to the drop size dependent power of the volume. For abundant small drops present, the exponent is 1 as assumed in the conventional approach. However, for rarer large drops, the exponents fall below unity. At small scales, therefore, the mean number of large drops decreases with volume at a slower rate than the conventional approach assumes, suggesting more large drops at these scales than conventional models account for; their impact is consequently underestimated. Size dependent models of spatial distribution of cloud drops that simulate the observed power laws show strong drop clustering, the more so the larger the drops. The degree of clustering is determined by the observed exponents. The strong clustering of large drops arises naturally from the observed power-law statistics. Current theories of photon-cloud interaction and warm rain formation will need radical revision in order to produce these statistics; their underlying equations are unable to yield the observed power law.

  8. EMAPS: An Efficient Multiscale Approach to Plasma Systems with Non-MHD Scale Effects

    SciTech Connect

    Omelchenko, Yuri A.; Karimabadi, Homa

    2014-10-14

    Using Discrete-Event Simulation (DES) as a novel paradigm for time integration of large-scale physics-driven systems, we have achieved significant breakthroughs in simulations of multi-dimensional magnetized plasmas where ion kinetic and finite Larmor radius (FLR) and Hall effects play a crucial role. For these purposes we apply a unique asynchronous simulation tool: a parallel, electromagnetic Particle-in-Cell (PIC) code, HYPERS (Hybrid Particle Event-Resolved Simulator), which treats plasma electrons as a charge neutralizing fluid and solves a self-consistent set of non-radiative Maxwell, electron fluid equations and ion particle equations on a structured computational grid. HYPERS enables adaptive local time steps for particles, fluid elements and electromagnetic fields. This ensures robustness (stability) and efficiency (speed) of highly dynamic and nonlinear simulations of compact plasma systems such spheromaks, FRCs, ion beams and edge plasmas. HYPERS is a unique asynchronous code that has been designed to serve as a test bed for developing multi-physics applications not only for laboratory plasma devices but generally across a number of plasma physics fields, including astrophysics, space physics and electronic devices. We have made significant improvements to the HYPERS core: (1) implemented a new asynchronous magnetic field integration scheme that preserves local divB=0 to within round-off errors; (2) Improved staggered-grid discretizations of electric and magnetic fields. These modifications have significantly enhanced the accuracy and robustness of 3D simulations. We have conducted first-ever end-to-end 3D simulations of merging spheromak plasmas. The preliminary results show: (1) tilt-driven relaxation of a freely expanding spheromak to an m=1 Taylor helix configuration and (2) possibility of formation of a tilt-stable field-reversed configuration via merging and magnetic reconnection of two double-sided spheromaks with opposite helicities.

  9. UAV Data Processing for Large Scale Topographical Mapping

    NASA Astrophysics Data System (ADS)

    Tampubolon, W.; Reinhardt, W.

    2014-06-01

    Large scale topographical mapping in the third world countries is really a prominent challenge in geospatial industries nowadays. On one side the demand is significantly increasing while on the other hand it is constrained by limited budgets available for mapping projects. Since the advent of Act Nr.4/yr.2011 about Geospatial Information in Indonesia, large scale topographical mapping has been on high priority for supporting the nationwide development e.g. detail spatial planning. Usually large scale topographical mapping relies on conventional aerial survey campaigns in order to provide high resolution 3D geospatial data sources. Widely growing on a leisure hobby, aero models in form of the so-called Unmanned Aerial Vehicle (UAV) bring up alternative semi photogrammetric aerial data acquisition possibilities suitable for relatively small Area of Interest (AOI) i.e. <5,000 hectares. For detail spatial planning purposes in Indonesia this area size can be used as a mapping unit since it usually concentrates on the basis of sub district area (kecamatan) level. In this paper different camera and processing software systems will be further analyzed for identifying the best optimum UAV data acquisition campaign components in combination with the data processing scheme. The selected AOI is covering the cultural heritage of Borobudur Temple as one of the Seven Wonders of the World. A detailed accuracy assessment will be concentrated within the object feature of the temple at the first place. Feature compilation involving planimetric objects (2D) and digital terrain models (3D) will be integrated in order to provide Digital Elevation Models (DEM) as the main interest of the topographic mapping activity. By doing this research, incorporating the optimum amount of GCPs in the UAV photo data processing will increase the accuracy along with its high resolution in 5 cm Ground Sampling Distance (GSD). Finally this result will be used as the benchmark for alternative geospatial

  10. Very large-scale motions in a turbulent pipe flow

    NASA Astrophysics Data System (ADS)

    Lee, Jae Hwa; Jang, Seong Jae; Sung, Hyung Jin

    2011-11-01

    Direct numerical simulation of a turbulent pipe flow with ReD=35000 was performed to investigate the spatially coherent structures associated with very large-scale motions. The corresponding friction Reynolds number, based on pipe radius R, is R+=934, and the computational domain length is 30 R. The computed mean flow statistics agree well with previous DNS data at ReD=44000 and 24000. Inspection of the instantaneous fields and two-point correlation of the streamwise velocity fluctuations showed that the very long meandering motions exceeding 25R exist in logarithmic and wake regions, and the streamwise length scale is almost linearly increased up to y/R ~0.3, while the structures in the turbulent boundary layer only reach up to the edge of the log-layer. Time-resolved instantaneous fields revealed that the hairpin packet-like structures grow with continuous stretching along the streamwise direction and create the very large-scale structures with meandering in the spanwise direction, consistent with the previous conceptual model of Kim & Adrian (1999). This work was supported by the Creative Research Initiatives of NRF/MEST of Korea (No. 2011-0000423).

  11. Large-scale Direct Targeting for Drug Repositioning and Discovery

    PubMed Central

    Zheng, Chunli; Guo, Zihu; Huang, Chao; Wu, Ziyin; Li, Yan; Chen, Xuetong; Fu, Yingxue; Ru, Jinlong; Ali Shar, Piar; Wang, Yuan; Wang, Yonghua

    2015-01-01

    A system-level identification of drug-target direct interactions is vital to drug repositioning and discovery. However, the biological means on a large scale remains challenging and expensive even nowadays. The available computational models mainly focus on predicting indirect interactions or direct interactions on a small scale. To address these problems, in this work, a novel algorithm termed weighted ensemble similarity (WES) has been developed to identify drug direct targets based on a large-scale of 98,327 drug-target relationships. WES includes: (1) identifying the key ligand structural features that are highly-related to the pharmacological properties in a framework of ensemble; (2) determining a drug’s affiliation of a target by evaluation of the overall similarity (ensemble) rather than a single ligand judgment; and (3) integrating the standardized ensemble similarities (Z score) by Bayesian network and multi-variate kernel approach to make predictions. All these lead WES to predict drug direct targets with external and experimental test accuracies of 70% and 71%, respectively. This shows that the WES method provides a potential in silico model for drug repositioning and discovery. PMID:26155766

  12. Systematic renormalization of the effective theory of Large Scale Structure

    SciTech Connect

    Abolhasani, Ali Akbar; Mirbabayi, Mehrdad; Pajer, Enrico

    2016-05-31

    A perturbative description of Large Scale Structure is a cornerstone of our understanding of the observed distribution of matter in the universe. Renormalization is an essential and defining step to make this description physical and predictive. Here we introduce a systematic renormalization procedure, which neatly associates counterterms to the UV-sensitive diagrams order by order, as it is commonly done in quantum field theory. As a concrete example, we renormalize the one-loop power spectrum and bispectrum of both density and velocity. In addition, we present a series of results that are valid to all orders in perturbation theory. First, we show that while systematic renormalization requires temporally non-local counterterms, in practice one can use an equivalent basis made of local operators. We give an explicit prescription to generate all counterterms allowed by the symmetries. Second, we present a formal proof of the well-known general argument that the contribution of short distance perturbations to large scale density contrast δ and momentum density π(k) scale as k{sup 2} and k, respectively. Third, we demonstrate that the common practice of introducing counterterms only in the Euler equation when one is interested in correlators of δ is indeed valid to all orders.

  13. A study of synthetic large scales in turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Duvvuri, Subrahmanyam; Luhar, Mitul; Barnard, Casey; Sheplak, Mark; McKeon, Beverley

    2013-11-01

    Synthetic spanwise-constant spatio-temporal disturbances are excited in a turbulent boundary layer through a spatially impulsive patch of dynamic wall-roughness. The downstream flow response is studied through hot wire anemometry, pressure measurements at the wall and direct measurements of wall-shear-stress made using a novel micro-machined capacitive floating element sensor. These measurements are phase-locked to the input perturbation to recover the synthetic large-scale motion and characterize its structure and wall signature. The phase relationship between the synthetic large scale and small scale activity provides further insights into the apparent amplitude modulation effect between them, and the dynamics of wall-bounded turbulent flows in general. Results from these experiments will be discussed in the context of the critical-layer behavior revealed by the resolvent analysis of McKeon & Sharma (J Fluid Mech, 2010), and compared with similar earlier work by Jacobi & McKeon (J Fluid Mech, 2011). Model predictions are shown to be in broad agreement with experiments. The support of AFOSR grant #FA 9550-12-1-0469, Resnick Institute Graduate Research Fellowship (S.D.) and Sandia Graduate Fellowship (C.B.) are gratefully acknowledged.

  14. Simulations of Super Alfvenic Laser Ablation Experiments in the Large Plasma Device

    NASA Astrophysics Data System (ADS)

    Clark, Stephen Eric

    Hybrid plasma simulations, consisting of kinetic ions treated using standard Particle- In-Cell (PIC) techniques and an inertialess charge-neutralizing electron fluid, have been used to investigate the properties of collisionless shocks for a number of years. They agree well with sparse data obtained by flying through Earth's bow shock and have been used to model high energy explosions in the ionosphere. In this doctoral dissertation hybrid plasma simulation is used on much smaller scales to model collisionless shocks in a controlled laboratory setting. Initially a two-dimensional hybrid code from Los Alamos National Laboratory was used to find the best experimental parameters for shock formation, and interpret experimental data. It was demonstrated using the hybrid code that the experimental parameters needed to generate a shock in the laboratory are relaxed compared to previous work that was done. It was also shown that stronger shocks can be generated when running into a density gradient. Laboratory experiments at the University of California at Los Angeles using the high energy kJ-class Nd:Glass 1053 nm Raptor laser, and later the low energy yet high repetition rate 25 J Nd:Glass 1053 nm Peening laser have been performed in the Large Plasma Device (LAPD), which have provided some much needed data to benchmark the hybrid simulation method. The LAPD provides a repeatable, quiescent, ambient magnetized plasma to surround the exploding laser produced plasma that is ablated from a High Density Polyethylene (HDPE) target. The plasma density peaks in the machine at ni O(1013 cm-3 ), which is sufficiently dense to strongly couple energy and momentum from a laser ablated carbon plasma ejected from the HDPE target into the magnetized ambient plasma. It has been demonstrated that a sub-critical shock is formed in the LAPD using the high energy Raptor laser, though the data from this experiment is scant. Hybrid simulation was used as an analysis tool for the shock

  15. Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Riley, Peter

    1999-01-01

    This investigation is concerned with the large-scale evolution and topology of Coronal Mass Ejections (CMEs) in the solar wind. During this reporting period we have analyzed a series of low density intervals in the ACE (Advanced Composition Explorer) plasma data set that bear many similarities to CMEs. We have begun a series of 3D, MHD (Magnetohydrodynamics) coronal models to probe potential causes of these events. We also edited two manuscripts concerning the properties of CMEs in the solar wind. One was re-submitted to the Journal of Geophysical Research.

  16. How large is large enough for insects? Forest fragmentation effects at three spatial scales

    NASA Astrophysics Data System (ADS)

    Ribas, C. R.; Sobrinho, T. G.; Schoereder, J. H.; Sperber, C. F.; Lopes-Andrade, C.; Soares, S. M.

    2005-02-01

    Several mechanisms may lead to species loss in fragmented habitats, such as edge and shape effects, loss of habitat and heterogeneity. Ants and crickets were sampled in 18 forest remnants in south-eastern Brazil, to test whether a group of small remnants maintains the same insect species richness as similar sized large remnants, at three spatial scales. We tested hypotheses about alpha and gamma diversity to explain the results. Groups of remnants conserve as many species of ants as a single one. Crickets, however, showed a scale-dependent pattern: at small scales there was no significant or important difference between groups of remnants and a single one, while at the larger scale the group of remnants maintained more species. Alpha diversity (local species richness) was similar in a group of remnants and in a single one, at the three spatial scales, both for ants and crickets. Gamma diversity, however, varied both with taxa (ants and crickets) and spatial scale, which may be linked to insect mobility, remnant isolation, and habitat heterogeneity. Biological characteristics of the organisms involved have to be considered when studying fragmentation effects, as well as spatial scale at which it operates. Mobility of the organisms influences fragmentation effects, and consequently conservation strategies.

  17. Towards large scale production and separation of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Alvarez, Noe T.

    Since their discovery, carbon nanotubes (CNTs) have boosted the research and applications of nanotechnology; however, many applications of CNTs are inaccessible because they depend upon large-scale CNT production and separations. Type, chirality and diameter control of CNTs determine many of their physical properties, and such control is still not accesible. This thesis studies the fundamentals for scalable selective reactions of HiPCo CNTs as well as the early phase of routes to an inexpensive approach for large-scale CNT production. In the growth part, this thesis covers a complete wet-chemistry process of catalyst and catalyst support deposition for growth of vertically aligned (VA) CNTs. A wet-chemistry preparation process has significant importance for CNT synthesis through chemical vapor deposition (CVD). CVD is by far, the most suitable and inexpensive process for large-scale CNT production when compared to other common processes such as laser ablation and arc discharge. However, its potential has been limited by low-yielding and difficult preparation processes of catalyst and its support, therefore its competitiveness has been reduced. The wet-chemistry process takes advantage of current nanoparticle technology to deposit the catalyst and the catalyst support as a thin film of nanoparticles, making the protocol simple compared to electron beam evaporation and sputtering processes. In the CNT selective reactions part, this thesis studies UV irradiation of individually dispersed HiPCo CNTs that generates auto-selective reactions in the liquid phase with good control over their diameter and chirality. This technique is ideal for large-scale and continuous-process of separations of CNTs by diameter and type. Additionally, an innovative simple catalyst deposition through abrasion is demonstrated. Simple friction between the catalyst and the substrates deposit a high enough density of metal catalyst particles for successful CNT growth. This simple approach has

  18. Large-scale quantum photonic circuits in silicon

    NASA Astrophysics Data System (ADS)

    Harris, Nicholas C.; Bunandar, Darius; Pant, Mihir; Steinbrecher, Greg R.; Mower, Jacob; Prabhu, Mihika; Baehr-Jones, Tom; Hochberg, Michael; Englund, Dirk

    2016-08-01

    Quantum information science offers inherently more powerful methods for communication, computation, and precision measurement that take advantage of quantum superposition and entanglement. In recent years, theoretical and experimental advances in quantum computing and simulation with photons have spurred great interest in developing large photonic entangled states that challenge today's classical computers. As experiments have increased in complexity, there has been an increasing need to transition bulk optics experiments to integrated photonics platforms to control more spatial modes with higher fidelity and phase stability. The silicon-on-insulator (SOI) nanophotonics platform offers new possibilities for quantum optics, including the integration of bright, nonclassical light sources, based on the large third-order nonlinearity (χ(3)) of silicon, alongside quantum state manipulation circuits with thousands of optical elements, all on a single phase-stable chip. How large do these photonic systems need to be? Recent theoretical work on Boson Sampling suggests that even the problem of sampling from e30 identical photons, having passed through an interferometer of hundreds of modes, becomes challenging for classical computers. While experiments of this size are still challenging, the SOI platform has the required component density to enable low-loss and programmable interferometers for manipulating hundreds of spatial modes. Here, we discuss the SOI nanophotonics platform for quantum photonic circuits with hundreds-to-thousands of optical elements and the associated challenges. We compare SOI to competing technologies in terms of requirements for quantum optical systems. We review recent results on large-scale quantum state evolution circuits and strategies for realizing high-fidelity heralded gates with imperfect, practical systems. Next, we review recent results on silicon photonics-based photon-pair sources and device architectures, and we discuss a path towards

  19. Maestro: An Orchestration Framework for Large-Scale WSN Simulations

    PubMed Central

    Riliskis, Laurynas; Osipov, Evgeny

    2014-01-01

    Contemporary wireless sensor networks (WSNs) have evolved into large and complex systems and are one of the main technologies used in cyber-physical systems and the Internet of Things. Extensive research on WSNs has led to the development of diverse solutions at all levels of software architecture, including protocol stacks for communications. This multitude of solutions is due to the limited computational power and restrictions on energy consumption that must be accounted for when designing typical WSN systems. It is therefore challenging to develop, test and validate even small WSN applications, and this process can easily consume significant resources. Simulations are inexpensive tools for testing, verifying and generally experimenting with new technologies in a repeatable fashion. Consequently, as the size of the systems to be tested increases, so does the need for large-scale simulations. This article describes a tool called Maestro for the automation of large-scale simulation and investigates the feasibility of using cloud computing facilities for such task. Using tools that are built into Maestro, we demonstrate a feasible approach for benchmarking cloud infrastructure in order to identify cloud Virtual Machine (VM)instances that provide an optimal balance of performance and cost for a given simulation. PMID:24647123

  20. Knocking down highly-ordered large-scale nanowire arrays.

    PubMed

    Pevzner, Alexander; Engel, Yoni; Elnathan, Roey; Ducobni, Tamir; Ben-Ishai, Moshit; Reddy, Koteeswara; Shpaisman, Nava; Tsukernik, Alexander; Oksman, Mark; Patolsky, Fernando

    2010-04-14

    The large-scale assembly of nanowire elements with controlled and uniform orientation and density at spatially well-defined locations on solid substrates presents one of the most significant challenges facing their integration in real-world electronic applications. Here, we present the universal "knocking-down" approach, based on the controlled in-place planarization of nanowire elements, for the formation of large-scale ordered nanowire arrays. The controlled planarization of the nanowires is achieved by the use of an appropriate elastomer-covered rigid-roller device. After being knocked down, each nanowire in the array can be easily addressed electrically, by a simple single photolithographic step, to yield a large number of nanoelectrical devices with an unprecedented high-fidelity rate. The approach allows controlling, in only two simple steps, all possible array parameters, that is, nanowire dimensions, chemical composition, orientation, and density. The resulting knocked-down arrays can be further used for the creation of massive nanoelectronic-device arrays. More than million devices were already fabricated with yields over 98% on substrate areas of up, but not limited to, to 10 cm(2).

  1. Maestro: an orchestration framework for large-scale WSN simulations.

    PubMed

    Riliskis, Laurynas; Osipov, Evgeny

    2014-03-18

    Contemporary wireless sensor networks (WSNs) have evolved into large and complex systems and are one of the main technologies used in cyber-physical systems and the Internet of Things. Extensive research on WSNs has led to the development of diverse solutions at all levels of software architecture, including protocol stacks for communications. This multitude of solutions is due to the limited computational power and restrictions on energy consumption that must be accounted for when designing typical WSN systems. It is therefore challenging to develop, test and validate even small WSN applications, and this process can easily consume significant resources. Simulations are inexpensive tools for testing, verifying and generally experimenting with new technologies in a repeatable fashion. Consequently, as the size of the systems to be tested increases, so does the need for large-scale simulations. This article describes a tool called Maestro for the automation of large-scale simulation and investigates the feasibility of using cloud computing facilities for such task. Using tools that are built into Maestro, we demonstrate a feasible approach for benchmarking cloud infrastructure in order to identify cloud Virtual Machine (VM)instances that provide an optimal balance of performance and cost for a given simulation.

  2. Detecting differential protein expression in large-scale population proteomics

    SciTech Connect

    Ryu, Soyoung; Qian, Weijun; Camp, David G.; Smith, Richard D.; Tompkins, Ronald G.; Davis, Ronald W.; Xiao, Wenzhong

    2014-06-17

    Mass spectrometry-based high-throughput quantitative proteomics shows great potential in clinical biomarker studies, identifying and quantifying thousands of proteins in biological samples. However, methods are needed to appropriately handle issues/challenges unique to mass spectrometry data in order to detect as many biomarker proteins as possible. One issue is that different mass spectrometry experiments generate quite different total numbers of quantified peptides, which can result in more missing peptide abundances in an experiment with a smaller total number of quantified peptides. Another issue is that the quantification of peptides is sometimes absent, especially for less abundant peptides and such missing values contain the information about the peptide abundance. Here, we propose a Significance Analysis for Large-scale Proteomics Studies (SALPS) that handles missing peptide intensity values caused by the two mechanisms mentioned above. Our model has a robust performance in both simulated data and proteomics data from a large clinical study. Because varying patients’ sample qualities and deviating instrument performances are not avoidable for clinical studies performed over the course of several years, we believe that our approach will be useful to analyze large-scale clinical proteomics data.

  3. Large-scale Biomedical Image Analysis in Grid Environments

    PubMed Central

    Kumar, Vijay S.; Rutt, Benjamin; Kurc, Tahsin; Catalyurek, Umit; Pan, Tony; Saltz, Joel; Chow, Sunny; Lamont, Stephan; Martone, Maryann

    2012-01-01

    Digital microscopy scanners are capable of capturing multi-Gigapixel images from single slides, thus producing images of sizes up to several tens of Gigabytes each, and a research study may have hundreds of slides from a specimen. The sheer size of the images and the complexity of image processing operations create roadblocks to effective integration of large-scale imaging data in research. This paper presents the application of a component-based Grid middleware system for processing extremely large images obtained from digital microscopy devices. We have developed parallel, out-of-core techniques for different classes of data processing operations commonly employed on images from confocal microscopy scanners. These techniques are combined into data pre-processing and analysis pipelines using the component-based middleware system. The experimental results show that 1) our implementation achieves good performance and can handle very large (terabyte-scale) datasets on high-performance Grid nodes, consisting of computation and/or storage clusters, and 2) it can take advantage of multiple Grid nodes connected over high-bandwidth wide-area networks by combining task- and data-parallelism. PMID:18348945

  4. Very-large-scale coherent motions in open channel flows

    NASA Astrophysics Data System (ADS)

    Zhong, Qiang; Hussain, Fazle; Li, Dan-Xun

    2016-11-01

    Very-large-scale coherent structures (VLSSs) - whose characteristic length is of the order of 10 h (h is the water depth) - are found to exist in the log and outer layers near the bed of open channel flows. For decades researchers have speculated that large coherent structures may exist in open channel flows. However, conclusive evidence is still lacking. The present study employed pre-multiplied velocity power spectral and co-spectral analyses of time-resolved PIV data obtained in open channel flows. In all cases, two modes - large-scale structures (of the order of h) and VLSSs - dominate the log and outer layers of the turbulent boundary layer. More than half of TKE and 40% of the Reynolds shear stress in the log and outer layers are contributed by VLSSs. The strength difference of VLSSs between open and closed channel flows leads to pronounced redistribution of TKE near the free surface of open channel flows, which is a unique phenomenon that sets the open channel flows apart from other wall-bounded turbulent flows. Funded by China Postdoctoral Science Foundation (No.2015M580105), National Natural Science Foundation of China (No.51127006).

  5. Large Scale Deformation Monitoring and Atmospheric Removal in Mexico City

    NASA Astrophysics Data System (ADS)

    McCardle, Adrian; McCardel, Jim; Ramos, Fernanda Ledo G.

    2010-03-01

    Large scale, accurate measurement of non-linear ground movement is required for monitoring applications pertaining to groundwater extraction, oil and gas production, and carbon capture and storage. Mexico City experiences severe subsidence as high as 35 centimeters per year due to continued exploitation of groundwater. Such extreme ground deformation has caused damage to infrastructure and many areas of the city are now subjected to periodic flooding. Furthermore, subsidence rates change seasonally creating a non-linear deformation signature manifesting over an area larger than 30 x 30 kilometers. The geographical location and climate of Mexico City, coupled with aforementioned subsidence characteristics create unique challenges for repeat-pass InSAR processing: Firstly, Mexico City is a tropical highland and experiences an oceanic climate that leads to significant temporal de-correlation. Secondly, the large magnitude subsidence leads to phase aliasing over coherent targets, particularly for interferograms with large temporal separation. Lastly, the expansive deformation is spatially correlated on scales similar to the long-range atmosphere, complicating the separation of the two signals. This paper discusses the results from the application of traditional DInSAR techniques combined with Multi-temporal InSAR Network Analysis processing algorithms to accurately identify and measure displacement, specifically in light of the challenges peculiar to Mexico City. Multi-temporal InSAR Network Analysis techniques are used to identify non-linear displacement and remove atmospheric noise from 38 ENVISAT images that were acquired over Mexico City from 2002 to 2007.

  6. A visual backchannel for large-scale events.

    PubMed

    Dörk, Marian; Gruen, Daniel; Williamson, Carey; Carpendale, Sheelagh

    2010-01-01

    We introduce the concept of a Visual Backchannel as a novel way of following and exploring online conversations about large-scale events. Microblogging communities, such as Twitter, are increasingly used as digital backchannels for timely exchange of brief comments and impressions during political speeches, sport competitions, natural disasters, and other large events. Currently, shared updates are typically displayed in the form of a simple list, making it difficult to get an overview of the fast-paced discussions as it happens in the moment and how it evolves over time. In contrast, our Visual Backchannel design provides an evolving, interactive, and multi-faceted visual overview of large-scale ongoing conversations on Twitter. To visualize a continuously updating information stream, we include visual saliency for what is happening now and what has just happened, set in the context of the evolving conversation. As part of a fully web-based coordinated-view system we introduce Topic Streams, a temporally adjustable stacked graph visualizing topics over time, a People Spiral representing participants and their activity, and an Image Cloud encoding the popularity of event photos by size. Together with a post listing, these mutually linked views support cross-filtering along topics, participants, and time ranges. We discuss our design considerations, in particular with respect to evolving visualizations of dynamically changing data. Initial feedback indicates significant interest and suggests several unanticipated uses.

  7. Large angular scale CMB anisotropy from an excited initial mode

    NASA Astrophysics Data System (ADS)

    Sojasi, A.; Mohsenzadeh, M.; Yusofi, E.

    2016-07-01

    According to inflationary cosmology, the CMB anisotropy gives an opportunity to test predictions of new physics hypotheses. The initial state of quantum fluctuations is one of the important options at high energy scale, as it can affect observables such as the CMB power spectrum. In this study a quasi-de Sitter inflationary background with approximate de Sitter mode function built over the Bunch-Davies mode is applied to investigate the scale-dependency of the CMB anisotropy. The recent Planck constraint on spectral index motivated us to examine the effect of a new excited mode function (instead of pure de Sitter mode) on the CMB anisotropy at large angular scales. In so doing, it is found that the angular scale-invariance in the CMB temperature fluctuations is broken and in the limit ℓ < 200 a tiny deviation appears. Also, it is shown that the power spectrum of CMB anisotropy is dependent on a free parameter with mass dimension H << M * < M p and on the slow-roll parameter ɛ. Supported by the Islamic Azad University, Rasht Branch, Rasht, Iran

  8. Termination shock response to large-scale solar wind fluctuations

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.

    1994-01-01

    The analysis of data recorded by the Voyager 2 spacecraft indicates the presence of large-scale fluctuations in the solar wind ram pressure on the time scale of tens of days. The amplitude of the fluctuations is highly variable but often lies within a factor of 5 to 10 change from an average or mean value of the ram pressure. Since the spacecraft has presumably not encountered the termination shock yet, these fluctuations should eventually interact with the shock and thereby play a role in determining the shock location. Numerical solutions of the time-dependent gasdynamic equations are used to simulate the response of the termination shock to fluctuations in the solar wind ram pressure comparable to those observed. The primary result of this study is that the maximum shock excursion due to the fluctuations is of the order of 1 AU, which is much smaller than that predicted by other studies. Additional simulations show that the limited movement is due to the fact that the time scale for the termination shock response is substantially larger than the time scale of the fluctuations. It is also shown that the heliopause acts as a barrier for the fluctuations and confines them to the heliosphere.

  9. Termination shock response to large-scale solar wind fluctuations

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.

    1994-01-01

    The analysis of data recorded by the Voyager 2 spacecraft indicates the presence of large-scale fluctuations in the solar wind ram pressure on the time scale of tens of days. The amplitude of the fluctuations is highly variable but often lies within a factor of 5 to 10 change from an average or mean value of the ram pressure. Since the spacecraft has presumably not encountered the termination shock yet, these fluctuations should eventually interact with the shock and thereby play a role in determining the shock location. Numerical solutions of the time-dependent gas dynamic equations are used to simulate the response of the termination shock to fluctuations in the solar wind ram pressure comparable to those observed. The primary result of this study is that the maximum shock excursion due to the fluctuations is of the order of 1 AU, which is much smaller than that predicted by other studies. Additional simulations show that the limited movement is due to the fact that the time scale for the termination shock response is substantially larger than the time scale of the fluctuations. It is also shown that the heliopause acts as a barrier for the fluctuations and confines them to the heliosphere.

  10. Large-scale diffusion of entangled polymers along nanochannels

    NASA Astrophysics Data System (ADS)

    Saalwachter, Kay; Lange, Frank; Steinhart, Martin; Judeinstein, Patrick

    2015-03-01

    Confinement-induced changes in polymer mobility are still under active discussion. For weakly interacting poly(butadiene) chains in 100 μm long, 20 and 60 nm wide channels in anodic Al2O3, we here report on the study of the large-scale pore-averaged self diffusion on a μm scale by 1H pulsed-gradient NMR. We find weak indications of an acceleration due to surface-induced disentanglement. Unlike previous reports on polymer diffusion into particle nanocomposites of similar confinement scale, or start-up diffusivities out of even thinner films, we find an MW and temperature independent reduction of diffusivity that is solely determined by the confinement size. We rationalize this trend by a simple volume-average model, which suggests a 20-fold surface-enhanced monomeric friction on the scale of the packing length, which can be compared to a factor of 300 that our model predicts for comparable thin-film data of poly(styrene) on silica.

  11. Punishment sustains large-scale cooperation in prestate warfare.

    PubMed

    Mathew, Sarah; Boyd, Robert

    2011-07-12

    Understanding cooperation and punishment in small-scale societies is crucial for explaining the origins of human cooperation. We studied warfare among the Turkana, a politically uncentralized, egalitarian, nomadic pastoral society in East Africa. Based on a representative sample of 88 recent raids, we show that the Turkana sustain costly cooperation in combat at a remarkably large scale, at least in part, through punishment of free-riders. Raiding parties comprised several hundred warriors and participants are not kin or day-to-day interactants. Warriors incur substantial risk of death and produce collective benefits. Cowardice and desertions occur, and are punished by community-imposed sanctions, including collective corporal punishment and fines. Furthermore, Turkana norms governing warfare benefit the ethnolinguistic group, a population of a half-million people, at the expense of smaller social groupings. These results challenge current views that punishment is unimportant in small-scale societies and that human cooperation evolved in small groups of kin and familiar individuals. Instead, these results suggest that cooperation at the larger scale of ethnolinguistic units enforced by third-party sanctions could have a deep evolutionary history in the human species.

  12. Atypical Behavior Identification in Large Scale Network Traffic

    SciTech Connect

    Best, Daniel M.; Hafen, Ryan P.; Olsen, Bryan K.; Pike, William A.

    2011-10-23

    Cyber analysts are faced with the daunting challenge of identifying exploits and threats within potentially billions of daily records of network traffic. Enterprise-wide cyber traffic involves hundreds of millions of distinct IP addresses and results in data sets ranging from terabytes to petabytes of raw data. Creating behavioral models and identifying trends based on those models requires data intensive architectures and techniques that can scale as data volume increases. Analysts need scalable visualization methods that foster interactive exploration of data and enable identification of behavioral anomalies. Developers must carefully consider application design, storage, processing, and display to provide usability and interactivity with large-scale data. We present an application that highlights atypical behavior in enterprise network flow records. This is accomplished by utilizing data intensive architectures to store the data, aggregation techniques to optimize data access, statistical techniques to characterize behavior, and a visual analytic environment to render the behavioral trends, highlight atypical activity, and allow for exploration.

  13. Towards large-scale, human-based, mesoscopic neurotechnologies.

    PubMed

    Chang, Edward F

    2015-04-08

    Direct human brain recordings have transformed the scope of neuroscience in the past decade. Progress has relied upon currently available neurophysiological approaches in the context of patients undergoing neurosurgical procedures for medical treatment. While this setting has provided precious opportunities for scientific research, it also has presented significant constraints on the development of new neurotechnologies. A major challenge now is how to achieve high-resolution spatiotemporal neural recordings at a large scale. By narrowing the gap between current approaches, new directions tailored to the mesoscopic (intermediate) scale of resolution may overcome the barriers towards safe and reliable human-based neurotechnology development, with major implications for advancing both basic research and clinical translation.

  14. Large-scale treeline changes recorded in Siberia

    NASA Astrophysics Data System (ADS)

    Esper, Jan; Schweingruber, Fritz H.

    2004-03-01

    Analysis of a multi-species network of western Siberian ecotone sites revealed pulses of tree invasion into genuine treeless tundra environments in the 1940s and 1950s and after the early 1970s. In addition, increases in radial stem growth synchronous to the late 20th century treeline change are observed. Both treeline changes and growth increases correspond with decadal-scale periods of temperature that are warmer than in any other period since observations started, suggesting - even if indirect - the sensitivity of large-scale treeline changes to this climatic forcing. The mid 20th century recruitment period reported here for the western Siberian network is compared with local findings from Europe and North America suggesting a circumpolar trend perhaps related to climate warming patterns. For western Siberia, the presence of relict stumps, nevertheless, indicates that this present colonization is reoccupying sites that had tree cover earlier in the last millennium.

  15. Large Scale Electronic Structure Calculations using Quantum Chemistry Methods

    NASA Astrophysics Data System (ADS)

    Scuseria, Gustavo E.

    1998-03-01

    This talk will address our recent efforts in developing fast, linear scaling electronic structure methods for large scale applications. Of special importance is our fast multipole method( M. C. Strain, G. E. Scuseria, and M. J. Frisch, Science 271), 51 (1996). (FMM) for achieving linear scaling for the quantum Coulomb problem (GvFMM), the traditional bottleneck in quantum chemistry calculations based on Gaussian orbitals. Fast quadratures(R. E. Stratmann, G. E. Scuseria, and M. J. Frisch, Chem. Phys. Lett. 257), 213 (1996). combined with methods that avoid the Hamiltonian diagonalization( J. M. Millam and G. E. Scuseria, J. Chem. Phys. 106), 5569 (1997) have resulted in density functional theory (DFT) programs that can be applied to systems containing many hundreds of atoms and ---depending on computational resources or level of theory-- to many thousands of atoms.( A. D. Daniels, J. M. Millam and G. E. Scuseria, J. Chem. Phys. 107), 425 (1997). Three solutions for the diagonalization bottleneck will be analyzed and compared: a conjugate gradient density matrix search (CGDMS), a Hamiltonian polynomial expansion of the density matrix, and a pseudo-diagonalization method. Besides DFT, our near-field exchange method( J. C. Burant, G. E. Scuseria, and M. J. Frisch, J. Chem. Phys. 105), 8969 (1996). for linear scaling Hartree-Fock calculations will be discussed. Based on these improved capabilities, we have also developed programs to obtain vibrational frequencies (via analytic energy second derivatives) and excitation energies (through time-dependent DFT) of large molecules like porphyn or C_70. Our GvFMM has been extended to periodic systems( K. N. Kudin and G. E. Scuseria, Chem. Phys. Lett., in press.) and progress towards a Gaussian-based DFT and HF program for polymers and solids will be reported. Last, we will discuss our progress on a Laplace-transformed \\cal O(N^2) second-order pertubation theory (MP2) method.

  16. Large-scale investigation of the parameters in response to Eimeria maxima challenge in broilers.

    PubMed

    Hamzic, E; Bed'Hom, B; Juin, H; Hawken, R; Abrahamsen, M S; Elsen, J M; Servin, B; Pinard-van der Laan, M H; Demeure, O

    2015-04-01

    Coccidiosis, a parasitic disease of the intestinal tract caused by members of the genera Eimeria and Isospora, is one of the most common and costly diseases in chicken. The aims of this study were to assess the effect of the challenge and level of variability of measured parameters in chickens during the challenge with Eimeria maxima. Furthermore, this study aimed to investigate which parameters are the most relevant indicators of the health status. Finally, the study also aimed to estimate accuracy of prediction for traits that cannot be measured on large scale (such as intestinal lesion score and fecal oocyst count) using parameters that can easily be measured on all animals. The study was performed in 2 parts: a pilot challenge on 240 animals followed by a large-scale challenge on 2,024 animals. In both experiments, animals were challenged with 50,000 Eimeria maxima oocysts at 16 d of age. In the pilot challenge, all animals were measured for BW gain, plasma coloration, hematocrit, and rectal temperature and, in addition, a subset of 48 animals was measured for oocyst count and the intestinal lesion score. All animals from the second challenge were measured for BW gain, plasma coloration, and hematocrit whereas a subset of 184 animals was measured for intestinal lesion score, fecal oocyst count, blood parameters, and plasma protein content and composition. Most of the parameters measured were significantly affected by the challenge. Lesion scores for duodenum and jejunum (P < 0.001), oocyst count (P < 0.05), plasma coloration for the optical density values between 450 and 490 nm (P < 0.001), albumin (P < 0.001), α1-globulin (P < 0.01), α2-globulin (P < 0.001), α3-globulin (P < 0.01), and β2-globulin (P < 0.001) were the most strongly affected parameters and expressed the greatest levels of variation. Plasma protein profiles proved to be a new, reliable parameter for measuring response to Eimeria maxima. Prediction of intestinal lesion score and fecal oocyst

  17. Remote visualization and scale analysis of large turbulence datatsets

    NASA Astrophysics Data System (ADS)

    Livescu, D.; Pulido, J.; Burns, R.; Canada, C.; Ahrens, J.; Hamann, B.

    2015-12-01

    Accurate simulations of turbulent flows require solving all the dynamically relevant scales of motions. This technique, called Direct Numerical Simulation, has been successfully applied to a variety of simple flows; however, the large-scale flows encountered in Geophysical Fluid Dynamics (GFD) would require meshes outside the range of the most powerful supercomputers for the foreseeable future. Nevertheless, the current generation of petascale computers has enabled unprecedented simulations of many types of turbulent flows which focus on various GFD aspects, from the idealized configurations extensively studied in the past to more complex flows closer to the practical applications. The pace at which such simulations are performed only continues to increase; however, the simulations themselves are restricted to a small number of groups with access to large computational platforms. Yet the petabytes of turbulence data offer almost limitless information on many different aspects of the flow, from the hierarchy of turbulence moments, spectra and correlations, to structure-functions, geometrical properties, etc. The ability to share such datasets with other groups can significantly reduce the time to analyze the data, help the creative process and increase the pace of discovery. Using the largest DOE supercomputing platforms, we have performed some of the biggest turbulence simulations to date, in various configurations, addressing specific aspects of turbulence production and mixing mechanisms. Until recently, the visualization and analysis of such datasets was restricted by access to large supercomputers. The public Johns Hopkins Turbulence database simplifies the access to multi-Terabyte turbulence datasets and facilitates turbulence analysis through the use of commodity hardware. First, one of our datasets, which is part of the database, will be described and then a framework that adds high-speed visualization and wavelet support for multi-resolution analysis of

  18. High Fidelity Simulations of Large-Scale Wireless Networks

    SciTech Connect

    Onunkwo, Uzoma; Benz, Zachary

    2015-11-01

    The worldwide proliferation of wireless connected devices continues to accelerate. There are 10s of billions of wireless links across the planet with an additional explosion of new wireless usage anticipated as the Internet of Things develops. Wireless technologies do not only provide convenience for mobile applications, but are also extremely cost-effective to deploy. Thus, this trend towards wireless connectivity will only continue and Sandia must develop the necessary simulation technology to proactively analyze the associated emerging vulnerabilities. Wireless networks are marked by mobility and proximity-based connectivity. The de facto standard for exploratory studies of wireless networks is discrete event simulations (DES). However, the simulation of large-scale wireless networks is extremely difficult due to prohibitively large turnaround time. A path forward is to expedite simulations with parallel discrete event simulation (PDES) techniques. The mobility and distance-based connectivity associated with wireless simulations, however, typically doom PDES and fail to scale (e.g., OPNET and ns-3 simulators). We propose a PDES-based tool aimed at reducing the communication overhead between processors. The proposed solution will use light-weight processes to dynamically distribute computation workload while mitigating communication overhead associated with synchronizations. This work is vital to the analytics and validation capabilities of simulation and emulation at Sandia. We have years of experience in Sandia’s simulation and emulation projects (e.g., MINIMEGA and FIREWHEEL). Sandia’s current highly-regarded capabilities in large-scale emulations have focused on wired networks, where two assumptions prevent scalable wireless studies: (a) the connections between objects are mostly static and (b) the nodes have fixed locations.

  19. Infectious diseases in large-scale cat hoarding investigations.

    PubMed

    Polak, K C; Levy, J K; Crawford, P C; Leutenegger, C M; Moriello, K A

    2014-08-01

    Animal hoarders accumulate animals in over-crowded conditions without adequate nutrition, sanitation, and veterinary care. As a result, animals rescued from hoarding frequently have a variety of medical conditions including respiratory infections, gastrointestinal disease, parasitism, malnutrition, and other evidence of neglect. The purpose of this study was to characterize the infectious diseases carried by clinically affected cats and to determine the prevalence of retroviral infections among cats in large-scale cat hoarding investigations. Records were reviewed retrospectively from four large-scale seizures of cats from failed sanctuaries from November 2009 through March 2012. The number of cats seized in each case ranged from 387 to 697. Cats were screened for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) in all four cases and for dermatophytosis in one case. A subset of cats exhibiting signs of upper respiratory disease or diarrhea had been tested for infections by PCR and fecal flotation for treatment planning. Mycoplasma felis (78%), calicivirus (78%), and Streptococcus equi subspecies zooepidemicus (55%) were the most common respiratory infections. Feline enteric coronavirus (88%), Giardia (56%), Clostridium perfringens (49%), and Tritrichomonas foetus (39%) were most common in cats with diarrhea. The seroprevalence of FeLV and FIV were 8% and 8%, respectively. In the one case in which cats with lesions suspicious for dermatophytosis were cultured for Microsporum canis, 69/76 lesional cats were culture-positive; of these, half were believed to be truly infected and half were believed to be fomite carriers. Cats from large-scale hoarding cases had high risk for enteric and respiratory infections, retroviruses, and dermatophytosis. Case responders should be prepared for mass treatment of infectious diseases and should implement protocols to prevent transmission of feline or zoonotic infections during the emergency response and when

  20. Statistical analysis of large-scale neuronal recording data

    PubMed Central

    Reed, Jamie L.; Kaas, Jon H.

    2010-01-01

    Relating stimulus properties to the response properties of individual neurons and neuronal networks is a major goal of sensory research. Many investigators implant electrode arrays in multiple brain areas and record from chronically implanted electrodes over time to answer a variety of questions. Technical challenges related to analyzing large-scale neuronal recording data are not trivial. Several analysis methods traditionally used by neurophysiologists do not account for dependencies in the data that are inherent in multi-electrode recordings. In addition, when neurophysiological data are not best modeled by the normal distribution and when the variables of interest may not be linearly related, extensions of the linear modeling techniques are recommended. A variety of methods exist to analyze correlated data, even when data are not normally distributed and the relationships are nonlinear. Here we review expansions of the Generalized Linear Model designed to address these data properties. Such methods are used in other research fields, and the application to large-scale neuronal recording data will enable investigators to determine the variable properties that convincingly contribute to the variances in the observed neuronal measures. Standard measures of neuron properties such as response magnitudes can be analyzed using these methods, and measures of neuronal network activity such as spike timing correlations can be analyzed as well. We have done just that in recordings from 100-electrode arrays implanted in the primary somatosensory cortex of owl monkeys. Here we illustrate how one example method, Generalized Estimating Equations analysis, is a useful method to apply to large-scale neuronal recordings. PMID:20472395