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Sample records for volcanic pedestal topped

  1. Concrete pedestals for high-performance semiconductor production equipment

    Science.gov (United States)

    Vogen, Wayne; Franklin, Craig L.; Morneault, Joseph

    1999-09-01

    Concrete pedestals have many vibration and stiffness characteristics that make them a superior choice for sensitive semiconductor production equipment including scanners, scanning electron microscopes, focused ion beam millers and optical inspection equipment. Among the advantages of concrete pedestals are high inherent damping, monolithic construction that eliminates low stiffness joints common in steep pedestals, ability to reuse and ease of installation. Steel pedestals that have plates attached to the top of the frame are easily excited by acoustic excitation, especially in the range from 50 Hertz to 400 Hertz. Concrete pedestals do not suffer from this phenomenon because of the high mass and damping of the top surface.

  2. Analysis of pedestal plasma transport

    International Nuclear Information System (INIS)

    Callen, J.D.; Groebner, R.J.; Osborne, T.H.; Canik, J.M.; Owen, L.W.; Pankin, A.Y.; Rafiq, T.; Rognlien, T.D.; Stacey, W.M.

    2010-01-01

    An H-mode edge pedestal plasma transport benchmarking exercise was undertaken for a single DIII-D pedestal. Transport modelling codes used include 1.5D interpretive (ONETWO, GTEDGE), 1.5D predictive (ASTRA) and 2D ones (SOLPS, UEDGE). The particular DIII-D discharge considered is 98889, which has a typical low density pedestal. Profiles for the edge plasma are obtained from Thomson and charge-exchange recombination data averaged over the last 20% of the average 33.53 ms repetition time between type I edge localized modes. The modelled density of recycled neutrals is largest in the divertor X-point region and causes the edge plasma source rate to vary by a factor ∼10 2 on the separatrix. Modelled poloidal variations in the densities and temperatures on flux surfaces are small on all flux surfaces up to within about 2.6 mm (ρ N > 0.99) of the mid-plane separatrix. For the assumed Fick's-diffusion-type laws, the radial heat and density fluxes vary poloidally by factors of 2-3 in the pedestal region; they are largest on the outboard mid-plane where flux surfaces are compressed and local radial gradients are largest. Convective heat flows are found to be small fractions of the electron (∼ 2 s -1 . Electron heat transport is found to be best characterized by electron-temperature-gradient-induced transport at the pedestal top and paleoclassical transport throughout the pedestal. The effective ion heat diffusivity in the pedestal has a different profile from the neoclassical prediction and may be smaller than it. The very small effective density diffusivity may be the result of an inward pinch flow nearly balancing a diffusive outward radial density flux. The inward ion pinch velocity and density diffusion coefficient are determined by a new interpretive analysis technique that uses information from the force balance (momentum conservation) equations; the paleoclassical transport model provides a plausible explanation of these new results. Finally, the measurements

  3. An edge pedestal model

    International Nuclear Information System (INIS)

    Stacev, W.M.

    2001-01-01

    A new model for calculation of the gradient scale lengths in the edge pedestal region and of the edge transport barrier width in H-mode tokamak plasmas will be described. Model problem calculations which demonstrate the promise of this model for predicting experimental pedestal properties will be discussed. The density and Prague gradient scale lengths (L) in the edge are calculated from the particle and ion and electron energy radial transport equations, making use of (presumed) known particle and energy fluxes flowing across the edge transport barrier from the core into the SOL and of edge transport coefficients. The average values of the particle and heat fluxes in the edge transport barrier are calculated in terms of the fluxes crossing into the SOL and the atomic physics reaction rates (ionisation, charge-exchange, elastic scattering, impurity radiation) in the edge by integrating the respective transport equations from the pedestal to the separatrix. An important implication of this model is that the pedestal gradient scale lengths depend not just on local pedestal platers properties but also on particle and energy fluxes from the core plasma and on recycling neutral fluxes that penetrate into the plasma edge, both of which in turn depend on the pedestal properties. The MHD edge pressure gradient constraint α≤ α C is used to determine the pressure width of the edge transport barrier, Δ TB = Δ TB (α c ). Three different models for the MHD edge pressure gradient constraint have been investigated: (1) nominal ideal ballooning mode theory, (2) ballooning mode theory taking into account the edge geometry and shear to access He second stability region; and pedestal β-limit theory when the ballooning modes are stabilised by diamagnetic effects. A series of calculations have been made for a DIII-D model problem. The calculated gradient scale lengths and edge transport barrier widths are of the magnitude of values observed experimentally, and certain trends

  4. Inter-ELM pedestal structure development in ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Laggner, Florian Martin

    2017-06-15

    high field side high density region (HFSHD) is formed reaching up to the HFS midplane. Neither the timescale of the appearance of the HFSHD nor the increase of the main chamber neutral fluxes fit the timescale of the n{sub e} pedestal, which is faster. It is found that the recovery phase of the n{sub e} pedestal is linked to the magnetic activity at the LFS midplane. The fluctuation amplitude is strongly reduced during the re-establishment of the n{sub e} pedestal. The plasma shape, respectively triangularity (δ), impacts on the pedestal stability. In dedicated experiments it was found that the higher pedestal top n{sub e}, which is observed at high δ, is already established in the n{sub e} pedestal recovery phase. The lowering of the ELM repetition frequency (f{sub ELM}) with increasing δ is related to longer pedestal recovery phases. In all investigated discharge intervals, the pre-ELM pedestal profiles are in agreement with PB theory. The detailed investigation of the pedestal recovery phases after an ELM crash showed for the first time that the sequence of recovery phases evolves independently of main ion species, plasma collisionality and plasma shape till the stability limit, which is well described by PB theory, is reached. Furthermore, it was evidenced that the fast increase of the n{sub e} pedestal is not dominated by the neutral dynamics in the divertor or main chamber because it occurs on faster timescales. The magnetic fluctuations, occurring in the pre-ELM phase with constant pressure gradient, were characterised in detail for the first time. It has been shown that the underlying instability is located close to the minimum of the radial electric field, exhibits a toroidal mode number of 11 and is also detectable on the HFS, indicating a significant peeling contribution.

  5. A pedestal temperature model with self-consistent calculation of safety factor and magnetic shear

    International Nuclear Information System (INIS)

    Onjun, T; Siriburanon, T; Onjun, O

    2008-01-01

    A pedestal model based on theory-motivated models for the pedestal width and the pedestal pressure gradient is developed for the temperature at the top of the H-mode pedestal. The pedestal width model based on magnetic shear and flow shear stabilization is used in this study, where the pedestal pressure gradient is assumed to be limited by first stability of infinite n ballooning mode instability. This pedestal model is implemented in the 1.5D BALDUR integrated predictive modeling code, where the safety factor and magnetic shear are solved self-consistently in both core and pedestal regions. With the self-consistently approach for calculating safety factor and magnetic shear, the effect of bootstrap current can be correctly included in the pedestal model. The pedestal model is used to provide the boundary conditions in the simulations and the Multi-mode core transport model is used to describe the core transport. This new integrated modeling procedure of the BALDUR code is used to predict the temperature and density profiles of 26 H-mode discharges. Simulations are carried out for 13 discharges in the Joint European Torus and 13 discharges in the DIII-D tokamak. The average root-mean-square deviation between experimental data and the predicted profiles of the temperature and the density, normalized by their central values, is found to be about 14%

  6. Magnetic-flutter-induced pedestal plasma transport

    International Nuclear Information System (INIS)

    Callen, J.D.; Hegna, C.C.; Cole, A.J.

    2013-01-01

    Plasma toroidal rotation can limit reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational magnetic flux surfaces. Hence it causes the induced radial perturbations δB ρ to be small there, thereby inhibiting magnetic island formation and stochasticity at the top of pedestals in high (H-mode) confinement tokamak plasmas. However, the δB ρ s induced by RMPs increase away from rational surfaces and are shown to induce significant sinusoidal radial motion (flutter) of magnetic field lines with a radial extent that varies linearly with δB ρ and inversely with distance from the rational surface because of the magnetic shear. This produces a radial electron thermal diffusivity that is (1/2)(δB ρ /B 0 ) 2 times a kinetically derived, electron-collision-induced, magnetic-shear-reduced, effective parallel electron thermal diffusivity in the absence of magnetic stochasticity. These low collisionality flutter-induced transport processes and thin magnetic island effects are shown to be highly peaked in the vicinity of rational surfaces at the top of low collisionality pedestals. However, the smaller but finite level of magnetic-flutter-induced electron heat transport midway between rational surfaces is the primary factor that determines the electron temperature difference between rational surfaces at the pedestal top. The magnetic-flutter-induced non-ambipolar electron density transport can be large enough to push the plasma toward an electron density transport root. Requiring ambipolar density transport is shown to determine the radial electric field, the plasma toroidal rotation (via radial force balance), a reduced electron thermal diffusivity and increased ambipolar density transport in the pedestal. At high collisionality the various flutter effects are less strongly peaked at rational surfaces and generally less significant. They are thus less likely to exhibit flutter-induced resonant behaviour and transition toward an

  7. Magnetic-flutter-induced pedestal plasma transport

    Science.gov (United States)

    Callen, J. D.; Hegna, C. C.; Cole, A. J.

    2013-11-01

    Plasma toroidal rotation can limit reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational magnetic flux surfaces. Hence it causes the induced radial perturbations δBρ to be small there, thereby inhibiting magnetic island formation and stochasticity at the top of pedestals in high (H-mode) confinement tokamak plasmas. However, the δBρs induced by RMPs increase away from rational surfaces and are shown to induce significant sinusoidal radial motion (flutter) of magnetic field lines with a radial extent that varies linearly with δBρ and inversely with distance from the rational surface because of the magnetic shear. This produces a radial electron thermal diffusivity that is (1/2)(δBρ/B0)2 times a kinetically derived, electron-collision-induced, magnetic-shear-reduced, effective parallel electron thermal diffusivity in the absence of magnetic stochasticity. These low collisionality flutter-induced transport processes and thin magnetic island effects are shown to be highly peaked in the vicinity of rational surfaces at the top of low collisionality pedestals. However, the smaller but finite level of magnetic-flutter-induced electron heat transport midway between rational surfaces is the primary factor that determines the electron temperature difference between rational surfaces at the pedestal top. The magnetic-flutter-induced non-ambipolar electron density transport can be large enough to push the plasma toward an electron density transport root. Requiring ambipolar density transport is shown to determine the radial electric field, the plasma toroidal rotation (via radial force balance), a reduced electron thermal diffusivity and increased ambipolar density transport in the pedestal. At high collisionality the various flutter effects are less strongly peaked at rational surfaces and generally less significant. They are thus less likely to exhibit flutter-induced resonant behaviour and transition toward an electron

  8. Multiscale modelling for tokamak pedestals

    Science.gov (United States)

    Abel, I. G.

    2018-04-01

    Pedestal modelling is crucial to predict the performance of future fusion devices. Current modelling efforts suffer either from a lack of kinetic physics, or an excess of computational complexity. To ameliorate these problems, we take a first-principles multiscale approach to the pedestal. We will present three separate sets of equations, covering the dynamics of edge localised modes (ELMs), the inter-ELM pedestal and pedestal turbulence, respectively. Precisely how these equations should be coupled to each other is covered in detail. This framework is completely self-consistent; it is derived from first principles by means of an asymptotic expansion of the fundamental Vlasov-Landau-Maxwell system in appropriate small parameters. The derivation exploits the narrowness of the pedestal region, the smallness of the thermal gyroradius and the low plasma (the ratio of thermal to magnetic pressures) typical of current pedestal operation to achieve its simplifications. The relationship between this framework and gyrokinetics is analysed, and possibilities to directly match our systems of equations onto multiscale gyrokinetics are explored. A detailed comparison between our model and other models in the literature is performed. Finally, the potential for matching this framework onto an open-field-line region is briefly discussed.

  9. Pedestal Temperature Model for Type III ELMy H-mode Plasma

    International Nuclear Information System (INIS)

    Buangam, W.; Suwanna, S.; Onjun, T.; Poolyarat, N.; Picha, R.; Singhsomroje, W.

    2009-07-01

    Full text: It is widely known that the improved performance of H-mode plasma results mainly from a formation of the pedestal, which is a narrow region of strong pressure gradient near the edge of plasma. A predictive capability for the conditions at the top of the pedestal is important, especially for predictive simulations of future experiments. New models for predicting the temperature values at the top of the pedestal for type III ELMy H-mode plasma are developed by using two different approaches: a theory-based approaches and an empirical approach. For a theory-based approach, a model is developed based on the calculation of thermal energy in the pedestal region and on accepted scaling laws of energy confinement time. For an empirical model, a scaling law for pedestal temperature in terms of plasma controlled parameters, such as plasma current, magnetic field, heating power, is deduced from experimental data. Predictions from these models are compared with experimental data from the Pedestal International Database. Statistical quantities, such as Root-Mean Square Error (RMSE) and offset values, are computed to quantify the predictive capability of the models. It is found that the theory-based model predicts the pedestal temperature values moderately well yielding RMSE between 30% and 40%. The IPB98(y,3) scaling law yields with best agreement with RMSE of 30.4%. The empirical model predicts the pedestal temperature value with better agreement, yield RMSE of 25.9%

  10. H-mode pedestal characteristics on MAST

    International Nuclear Information System (INIS)

    Kirk, A; Counsell, G F; Arends, E; Meyer, H; Taylor, D; Valovic, M; Walsh, M; Wilson, H

    2004-01-01

    The H-mode pedestal characteristics on the mega ampere spherical tokamak (MAST) are measured in a variety of disconnected double null discharges and the effect of edge localized modes (ELMs) on the pedestal is presented. The edge density pedestal width in spatial co-ordinates is similar on both the inboard and outboard sides. Neutral penetration may be able to explain the density pedestal width but it alone cannot explain the characteristics of the temperature pedestal. The data from MAST can be used to improve temperature pedestal width scalings by extending the ranges in pedestal collisionality, magnetic field, elongation and aspect ratio studied by other machines. Convective transport is found to dominate energy losses during ELMs and the fractional loss of pedestal energy during an ELM on MAST correlates better with SOL ion transit time than with pedestal collisionality

  11. RMP-Flutter-Induced Pedestal Plasma Transport

    Energy Technology Data Exchange (ETDEWEB)

    Callen, J. D.; Hegna, C., E-mail: callen@engr.wisc.edu [University of Wisconsin, Madison (United States); Cole, A. J. [Columbia University, New York (United States)

    2012-09-15

    Full text: Plasma toroidal rotation can prevent or limit reconnection of externally applied resonant magnetic perturbation (RMP) fields {delta}B on rational magnetic flux surfaces. Hence, it causes the induced radial perturbations to vanish or be small there, and thereby inhibits magnetic island formation and stochasticity in the edge of high (H-mode) confinement tokamak plasmas. However, the radial component of the spatial magnetic flutter induced by RMP fields off rational surfaces causes a radial electron thermal diffusivity of (1/2)({delta}B{sub p}/B){sup 2} times a magnetic-shear-influenced effective parallel electron thermal diffusivity. The resultant RMP-flutter-induced electron thermal diffusivity can be comparable to experimentally inferred values at the top of H-mode pedestals. This process also causes a factor of about 3 smaller RMP-induced electron density diffusivity there. Because this electron density transport is non-ambipolar, it produces a toroidal torque on the plasma, which is usually in the co-current direction. Kinetic-based cylindrical screw-pinch and toroidal models of these RMP-flutter-induced plasma transport effects have been developed. The RMP-induced increases in these diffusive plasma transport processes are typically spatially inhomogeneous in that they are strongly peaked near the rational surfaces in low collisionality pedestals, which may lead to resonant sensitivities to the local safety factor q. The effects can be large enough to reduce the radially averaged gradients of the electron temperature and density at the top of H-mode edge pedestals, and modify the plasma toroidal rotation and radial electric field there. At high collisionality the various effects are less strongly peaked at rational surfaces and thus less likely to exhibit RMP-induced resonant behavior. These RMP-flutter-induced plasma transport processes provide a new paradigm for developing an understanding of how RMPs modify the pedestal structure to stabilize

  12. Improved understanding of physics processes in pedestal structure, leading to improved predictive capability for ITER

    International Nuclear Information System (INIS)

    Groebner, R.J.; Snyder, P.B.; Leonard, A.W.; Chang, C.S.; Maingi, R.; Boyle, D.P.; Diallo, A.; Hughes, J.W.; Davis, E.M.; Ernst, D.R.; Landreman, M.; Xu, X.Q.; Boedo, J.A.; Cziegler, I.; Diamond, P.H.; Eldon, D.P.; Callen, J.D.; Canik, J.M.; Elder, J.D.; Fulton, D.P.

    2013-01-01

    Joint experiment/theory/modelling research has led to increased confidence in predictions of the pedestal height in ITER. This work was performed as part of a US Department of Energy Joint Research Target in FY11 to identify physics processes that control the H-mode pedestal structure. The study included experiments on C-Mod, DIII-D and NSTX as well as interpretation of experimental data with theory-based modelling codes. This work provides increased confidence in the ability of models for peeling–ballooning stability, bootstrap current, pedestal width and pedestal height scaling to make correct predictions, with some areas needing further work also being identified. A model for pedestal pressure height has made good predictions in existing machines for a range in pressure of a factor of 20. This provides a solid basis for predicting the maximum pedestal pressure height in ITER, which is found to be an extrapolation of a factor of 3 beyond the existing data set. Models were studied for a number of processes that are proposed to play a role in the pedestal n e and T e profiles. These processes include neoclassical transport, paleoclassical transport, electron temperature gradient turbulence and neutral fuelling. All of these processes may be important, with the importance being dependent on the plasma regime. Studies with several electromagnetic gyrokinetic codes show that the gradients in and on top of the pedestal can drive a number of instabilities. (paper)

  13. Pedestal structure and stability in H-mode and I-mode: a comparative study on Alcator C-Mod

    International Nuclear Information System (INIS)

    Hughes, J.W.; Walk, J.R.; Davis, E.M.; LaBombard, B.; Baek, S.G.; Churchill, R.M.; Greenwald, M.; Hubbard, A.E.; Lipschultz, B.; Marmar, E.S.; Reinke, M.L.; Rice, J.E.; Theiler, C.; Terry, J.; White, A.E.; Whyte, D.G.; Snyder, P.B.; Groebner, R.J.; Osborne, T.; Diallo, A.

    2013-01-01

    New experimental data from the Alcator C-Mod tokamak are used to benchmark predictive modelling of the edge pedestal in various high-confinement regimes, contributing to greater confidence in projection of pedestal height and width in ITER and reactors. ELMy H-modes operate near stability limits for ideal peeling–ballooning modes, as shown by calculations with the ELITE code. Experimental pedestal width in ELMy H-mode scales as the square root of β pol at the pedestal top, i.e. the dependence expected from theory if kinetic ballooning modes (KBMs) were responsible for limiting the pedestal width. A search for KBMs in experiment has revealed a short-wavelength electromagnetic fluctuation in the pedestal that is a candidate driver for inter-edge localized mode (ELM) pedestal regulation. A predictive pedestal model (EPED) has been tested on an extended set of ELMy H-modes from C-Mod, reproducing pedestal height and width reasonably well across the data set, and extending the tested range of EPED to the highest absolute pressures available on any existing tokamak and to within a factor of three of the pedestal pressure targeted for ITER. In addition, C-Mod offers access to two regimes, enhanced D-alpha (EDA) H-mode and I-mode, that have high pedestals, but in which large ELM activity is naturally suppressed and, instead, particle and impurity transport are regulated continuously. Pedestals of EDA H-mode and I-mode discharges are found to be ideal magnetohydrodynamic (MHD) stable with ELITE, consistent with the general absence of ELM activity. Invocation of alternative physics mechanisms may be required to make EPED-like predictions of pedestals in these kinds of intrinsically ELM-suppressed regimes, which would be very beneficial to operation in burning plasma devices. (paper)

  14. Physics of the Tokamak Pedestal, and Implications for Magnetic Fusion Energy

    Science.gov (United States)

    Snyder, Philip

    2017-10-01

    High performance in tokamaks is achieved via the spontaneous formation of a transport barrier in the outer few percent of the confined plasma. This narrow insulating layer, referred to as a ``pedestal,'' typically results in a >30x increase in pressure across a 0.4-5cm layer. Predicted fusion power scales with the square of the pedestal top pressure (or ``pedestal height''), hence a fusion reactor strongly benefits from a high pedestal, provided this can be attained without large Edge Localized Modes (ELMs), which may erode plasma facing materials. The overlap of drift orbit, turbulence, and equilibrium scales across this narrow layer leads to rich and complex physics, and challenges traditional analytic and computational approaches. We review studies employing gyrokinetic, neoclassical, MHD, and other methods, which have explored how a range of instabilities, influenced by complex geometry, and strong ExB flows and bootstrap current, drive transport across the pedestal and guide its structure and dynamics. Development of high resolution diagnostics, and coordinated experiments on several tokamaks, have validated understanding of important aspects of the physics, while highlighting open issues. A predictive model (EPED) has proven capable of predicting the pedestal height and width to 20-25% accuracy in large statistical studies. This model was used to predict a new, high pedestal ``Super H-Mode'' regime, which was subsequently discovered on DIII-D, and motivated experiments on Alcator C-Mod which achieved world record, reactor relevant pedestal pressure. We review open issues including improved formalism, particle and momentum transport, the role of neutrals and impurities, ELM control, and pedestal formation. Finally we discuss coupling pedestal and core predictive models to enable more comprehensive optimization of the tokamak fusion concept. Supported by the US DOE under DE-FG02-95ER54309, FC02-06ER54873, DE-FC02-04ER54698, DE-FC02-99ER54512.

  15. Paleokarst on the top of the Maokou Formation: Further evidence for domal crustal uplift prior to the Emeishan flood volcanism

    Science.gov (United States)

    He, Bin; Xu, Yi-Gang; Guan, Jun-Peng; Zhong, Yu-Ting

    2010-09-01

    The ~ 260 Ma Emeishan Large Igneous Province (ELIP) in southwest China has previously been demonstrated to provide compelling evidence for pre-volcanic crustal doming in support of the mantle plume hypothesis. However this has been questioned by Ukstins-Peate and Bryan (2008) by showing hydrothermal magmatic activity at the Daqiao section. To solve this argument, a detailed characterization of the contact between the Emeishan basalts and the Maokou Formation was carried out. The contact is shown to be an unconformity, which is characterized by paleokarst on top of the Maokou Formation, including paleokarst relief, sinkholes, caves, tower karst and its corresponding rocks (such as kaolinite, bauxite and ferruginous duricrust and collapsed breccias, etc.). This paleokarst unconformity was in turn covered or infilled by the Emeishan basalts and tuffs, suggesting that uplift and erosion occurred prior to the eruption of the ELIP. The extent of erosion of the Maokou Formation indicates the ELIP can be divided into three roughly concentric zones: the inner, intermediate, and outer zones. The paleokarst features on the top of Maokou Formation vary across the ELIP. In the inner zone, a likely sinkhole and an incision valley with 450 m relief in height are found. In the intermediate zone, various paleokarst landforms such as karst relief, sinkholes and tower karsts are well developed. Some sinkholes that developed in the Qixia Formation below the Maokou Formation imply that the paleorelief is more than 350 m in height. In the outer zone, the paleokarstic surface is a paleo-weathering layer with minor karstification and development of caves at 10-50 m. This spatial variation of the paleokarst reflects variation of uplift height across the ELIP. The extent of minimal uplift is estimated to be at least 450 m in the inner zone, 350 m in the intermediate zone, whereas uplift is minor (tens-50 m) in the outer zone. The magnitude and shape of the uplift is roughly consistent with

  16. Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites

    Directory of Open Access Journals (Sweden)

    K. Zakšek

    2013-03-01

    Full Text Available Volcanic ash cloud-top height (ACTH can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach 30 km, which implies an ACTH of approximately 12 km at the beginning of the eruption. At the end of April eruption an ACTH of 3–4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

  17. The pinch of cold ions from recycling in the tokamak edge pedestal

    International Nuclear Information System (INIS)

    Wan Weigang; Parker, Scott E.; Chen Yang; Park, Gun-Young; Chang, Choong-Seock; Stotler, Daren

    2011-01-01

    We apply the ''natural fueling mechanism'' [W. Wan, S. E. Parker, Y. Chen, and F. W. Perkins, Phys. Plasmas 17, 040701 (2010)] to the edge pedestal. The natural fueling mechanism is where cold ions naturally pinch radially inward for a heat-flux dominated plasma. It is shown from neoclassical-neutral transport coupled simulations that the recycling neutrals and the associated source ions are colder than the main ions in the edge pedestal. These recycling source ions will pinch radially inward due to microturbulence. Gyrokinetic turbulence simulations indicate that near the top of the pedestal, the pinch velocity of the recycling source ions is much higher than the main ion outgoing flow velocity. The turbulent pinch of the recycling source ions may play a role in the edge pedestal transport and dynamics. The cold ion temperature significantly enhances the pinch velocity of the recycling source ions near to the pedestal top. Neoclassical calculations show a cold ion pinch in the pedestal as well.

  18. Pedestal width and ELM size identity studies in JET and DIII-D; implications for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Beurskens, M N A; Lomas, P; Saarelma, S; Balboa, I; Flanagan, J; Giroud, C; Kempenaars, M [EURATOM/UKAEA Fusion Association, Culham Sc. Centre, Abingdon, OX14 3DB (United Kingdom); Osborne, T H; Groebner, R; Leonard, A; Snyder, P B; Bray, B [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Horton, L D [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Frassinetti, L [Association EURATOM-VR, Alfven Laboratory, School of Electrical Engineering, KTH, Stockholm (Sweden); Nunes, I [Centro de Fusao Nuclear, Associacao EURATOM-IST, Lisboa (Portugal); Crombe, K [Department of Applied Physics, Ghent University, Rozier 44, 9000 Gent (Belgium); Giovannozzi, E [Associazione EURATOM-ENEA Sulla Fusione, Consorzio RFX Padova (Italy); Kohen, N [Association EURATOM-CEA, CEA/DSM/DRFC-Cadarache 13108, St Paul Durance (France); Loarte, A [ITER Organization, CS 90 046, F-13067 Saint Paul lez Durance Cedex (France); Loennroth, J, E-mail: Marc.Beurskens@jet.u [Association EURATOM-Tekes, Helsinki University of Technology (Finland)

    2009-12-15

    The dependence of the H-mode edge transport barrier width on normalized ion gyroradius (rho* = rho/a) in discharges with type I ELMs was examined in experiments combining data for the JET and DIII-D tokamaks. The plasma configuration as well as the local normalized pressure (beta), collisionality (nu*), Mach number and the ratio of ion and electron temperature at the pedestal top were kept constant, while rho* was varied by a factor of four. The width of the steep gradient region of the electron temperature (T{sub e}) and density (n{sub e}) pedestals normalized to machine size showed no or only a weak trend with rho*. A rho{sup 1/2} or rho{sup 1} dependence of the pedestal width, given by some theoretical predictions, is not supported by the current experiments. This is encouraging for the pedestal scaling towards ITER as it operates at lower rho* than existing devices. Some differences in pedestal structure and ELM behaviour were, however, found between the devices; in the DIII-D discharges, the n{sub e} and T{sub e} pedestal were aligned at high rho* but the n{sub e} pedestal shifted outwards in radius relative to T{sub e} as rho* decreases, while on JET the profiles remained aligned while rho* was scanned by a factor of two. The energy loss at an ELM normalized to the pedestal energy increased from 10% to 40% as rho* increased by a factor of two in the DIII-D discharges but no such variation was observed in the case of JET. The measured pedestal pressures and widths were found to be consistent with the predictions from modelling based on peeling-ballooning stability theory, and are used to make projections towards ITER

  19. Flux tube gyrokinetic simulations of the edge pedestal

    Science.gov (United States)

    Parker, Scott; Wan, Weigang; Chen, Yang

    2011-10-01

    The linear instabilities of DIII-D H-mode pedestal are studied with gyrokinetic micro-turbulence simulations. The simulation code GEM is an electromagnetic δf code with global tokamak geometry in the form of Miller equilibrium. Local flux tube simulations are carried out for multiple positions of two DIII-D profiles: shot #98889 and shot #131997. Near the top of the pedestal, the instability is clearly ITG. The dominant instability of the pedestal appears at the steep gradient region, and it is identified as a low frequency mode mostly driven by electron temperature gradient. The mode propagates along the electron diamagnetic direction for low n and may propagate along the ion direction for high n. At some positions near the steep gradient region, an ion instability is found which shows some characteristics of kinetic ballooning mode (KBM). These results will be compared to the results of E. Wang et al. and D. Fulton et al. in the same session. We thank R. Groebner and P. Snyder for providing experimental profiles and helpful discussions.

  20. Particle simulation of pedestal buildup and study of pedestal scaling law in a quiescent plasma edge

    International Nuclear Information System (INIS)

    Chang, C.S.; Ku, S.; Weitzner, H.; Groebner, R.; Osborne, T.

    2005-01-01

    A discrete guiding-center particle code XGC (X-point included Guiding Center code) is used to study pedestal buildup and sheared E r formation in a quiescent plasma edge of a diverted tokamak. A neoclassical pedestal scaling law has been deduced, which shows that the density pedestal width is proportional to T i 1/2 M 1/2 /B t where T i is the ion temperature, M is ion mass and B t is the toroidal magnetic field. Dependence on the pedestal density or the poloidal magnetic field is found to be much weaker. Ion temperature pedestal is not as well defined as the density pedestal. Neoclassical electron transport rate, including the collisional heat exchange rate with ions, is too slow to be considered in the time scale of simulation (∼ 10 ms). (author)

  1. Plasma shaping and its impact on the pedestal of ASDEX Upgrade: edge stability and inter-ELM dynamics at varied triangularity

    Science.gov (United States)

    Laggner, F. M.; Wolfrum, E.; Cavedon, M.; Dunne, M. G.; Birkenmeier, G.; Fischer, R.; Willensdorfer, M.; Aumayr, F.; The EUROfusion MST1 Team; The ASDEX Upgrade Team

    2018-04-01

    The plasma shape, in particular the triangularity (δ), impacts on the pedestal stability. A scan of δ including a variation of heating power (P heat) and gas puff was performed to study the behaviour of edge localised modes (ELMs) and the pre-ELM pedestal stability for different plasma shapes. Generally, at higher δ the pedestal top electron density (n e) is enhanced and the ELM repetition frequency (f ELM) is reduced. For all δ, the pedestal top n e is already fully established to its pre-ELM value during the initial recovery phase of the n e pedestal, which takes place immediately after the ELM crash. The lowering of the f ELM with increasing δ is related to longer pedestal recovery phases, especially the last pre-ELM phase with clamped pedestal gradients (after the recovery phases of the n e and electron temperature (T e) pedestal) is extended. In all investigated discharge intervals, the pre-ELM pedestal profiles are in agreement with peeling-ballooning (PB) theory. Over the investigated range of δ, two well-separated f ELM bands are observed in several discharge intervals. Their occurrence is linked to the inter-ELM pedestal stability. In both kinds of ELM cycles the pedestal evolves similarly, however, the ‘fast’ ELM cycle occurs before the global plasma stored energy (W MHD) increases, which then provides a stabilising effect on the pedestal, extending the inter-ELM period in the case of the ‘slow’ ELM cycle. At the end of a ‘fast’ ELM cycle the n e profile is radially shifted inwards relative to the n e profile at the end of a ‘slow’ ELM cycle, leading to a reduced pressure gradient. The appearance of two f ELM bands suggests that the pedestal becomes more likely PB unstable in certain phases of the inter-ELM evolution. Such a behaviour is possible because the evolution of the global plasma is not rigidly coupled to the evolution of the pedestal structure on the timescales of an ELM cycle.

  2. Pedestal performance dependence upon plasma shape in DIII-D

    International Nuclear Information System (INIS)

    Leonard, A.W.; Casper, T.A.; Groebner, R.J.; Osborne, T.H.; Snyder, P.B.; Thomas, D.M.

    2007-01-01

    Higher moments of the plasma shape than triangularity are found to significantly affect the pedestal pressure and the edge localized mode (ELM) characteristics in DIII-D. The shape dependence of the pedestal pressure was experimentally examined by varying the squareness in the proposed ITER configuration while holding the triangularity fixed. Over this scan the pedestal pressure increased by ∼50% from highest squareness to lowest squareness. The variation of pedestal energy is found to be consistent with the stability analysis of the measured profiles. The ELM energy also varied with the shape to maintain a nearly constant fraction of the pedestal energy. Stability analysis using model shapes and pressure profiles indicates that much of the advantage of high triangularity for high pedestal pressure can be achieved in lower triangularity shapes by optimizing squareness and/or the distance of the secondary upper separatrix from the primary separatrix. In high beta discharges an increase in pedestal pressure is observed with higher global stored energy. The greatest pedestal pressure increase is at low squareness due to an increase in both the pressure gradient stability limit and the width of the pedestal. The variation in pedestal pressure with squareness was also used to optimize 'hybrid' discharges in DIII-D where a lower pedestal pressure was required for an improved overall performance. In the 'hybrid' regime low squareness resulted in a high pedestal pressure with large infrequent ELMs that eventually triggered an internal 2/1 tearing mode that locked, resulting in a disruption. At higher squareness the pedestal pressure was reduced with smaller and more rapid ELMs, resulting in the maintenance of a steady beneficial internal 3/2 tearing mode and good confinement. For all the cases studied, an increase in the pedestal width at low squareness appears to be a significant factor in the increase in the total pedestal pressure

  3. Evolution of Edge Pedestal Profiles Between ELMs

    Science.gov (United States)

    Floyd, J. P.; Stacey, W. M.; Groebner, R. J.

    2012-10-01

    The measured edge profile evolution in DIII-D discharges is analyzed in terms of the implied thermal diffusivities, ion diffusion coefficients and pinch velocities, using the momentum-balance methodology of Ref. [1], extended to take into account ion orbit loss and X-point loss. The evolution of the density, temperature, rotation and radial electric field profiles in the edge pedestal between edge localized modes (ELMs) provides information of these diffusive and non-diffusive transport processes in the pedestal of H-mode plasmas. This methodology is incorporated in the GTEDGE code developed for DIII-D data interpretation. Using a smaller integration time for the charge exchange recombination measurements than in Ref. [1] allows a more detailed examination of the time evolution of the ion temperature and rotation profiles. 6pt [1] W.M. Stacey and R.J. Groebner, Nucl. Fusion 51, 063024 (2011).

  4. Hyraulic pedestal for a mine support

    Energy Technology Data Exchange (ETDEWEB)

    Nikonov, V IK; Gusel' nikov, L M; Iudin, N I; Miller, V B

    1981-04-30

    The goal of this invention is to provide additional brace support to a hydraulic pedestal and to provide for its operation in a given condition with steady resistance. In order to achieve this goal, the hydraulic accumulator is equipped with an intake valve with a valve lifter; this valve is built with a choke mounted on its axis. The hydraulic accumulator is built with a removable sectional upper section with a variable volume.

  5. Influence of plasma pedestal profiles on access to ELM-free regimes in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, S. Yu., E-mail: medvedev@a5.kiam.ru; Ivanov, A. A., E-mail: aai@a5.kiam.ru; Martynov, A. A., E-mail: martynov@a5.kiam.ru; Poshekhonov, Yu. Yu., E-mail: naida@a5.kiam.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Konovalov, S. V., E-mail: konoval-sv@nrcki.ru [National Research Nuclear University “MEPhI,” (Russian Federation); Polevoi, A. R., E-mail: alexei.polevoi@iter.org [ITER Organization (France)

    2016-05-15

    The influence of current density and pressure gradient profiles in the pedestal on the access to the regimes free from edge localized modes (ELMs) like quiescent H-mode in ITER is investigated. Using the simulator of MHD modes localized near plasma boundary based on the KINX code, calculations of the ELM stability were performed for the ITER plasma in scenarios 2 and 4 under variations of density and temperature profiles with the self-consistent bootstrap current in the pedestal. Low pressure gradient values at the separatrix, the same position of the density and temperature pedestals and high poloidal beta values facilitate reaching high current density in the pedestal and a potential transition into the regime with saturated large scale kink modes. New version of the localized MHD mode simulator allows one to compute the growth rates of ideal peeling-ballooning modes with different toroidal mode numbers and to determine the stability region taking into account diamagnetic stabilization. The edge stability diagrams computations and sensitivity studies of the stability limits to the value of diamagnetic frequency show that diamagnetic stabilization of the modes with high toroidal mode numbers can help to access the quiescent H-mode even with high plasma density but only with low pressure gradient values at the separatrix. The limiting pressure at the top of the pedestal increases for higher plasma density. With flat density profile the access to the quiescent H-mode is closed even with diamagnetic stabilization taken into account, while toroidal mode numbers of the most unstable peeling-ballooning mode decrease from n = 10−40 to n = 3−20.

  6. Characterisation of the ELM synchronized H-mode edge pedestal in ASDEX upgrade and DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Philip A.; Wolfrum, Elisabeth; Guenter, Sibylle; Kurzan, Bernd; Zohm, Hartmut [Max Planck Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Groebner, Rich; Osborne, Tom H.; Ferron, John; Snyder, Philip B. [General Atomics, San Diego, CA (United States); Dunne, Mike G. [Department of Physics, University College Cork, Association Euratom-DCU, Cork (Ireland); Collaboration: ASDEX Upgrade Team; DIII-D Team

    2011-07-01

    The results of a large database of edge pedestal data from type-I ELMy H-mode discharges from ASDEX Upgrade and DIII-D are presented. The data from high resolution edge diagnostics of both devices is analysed with the same analysis code in order to avoid systematic differences. Furthermore, sophisticated equilibrium reconstructions are used to asses uncertainties which arise during mapping from 2D real space coordinates to 1D flux coordinates. ELM synchronization allows the study of the pedestal structure at the ELM stability boundary. The pedestal is characterized by its top value, the gradient and the width. A large parameter range is covered by the two devices. Over this parameter range the profile shape of edge electron density differs from that of the temperature, irrespective of the device. However, the resulting electron pressure profile shape remains similar for all analysed H-Mode discharges.

  7. Numerical study of neoclassical plasma pedestal in a tokamak geometry

    International Nuclear Information System (INIS)

    Chang, C.S.; Ku, Seunghoe; Weitzner, H.

    2004-01-01

    The fundamental properties of steep neoclassical plasma pedestals in a quiescent tokamak plasma have been investigated with a new guiding center particle code XGC: an X-point included Guiding Center code. It is shown that the width of the steepest neoclassical pedestals is similar to an experimentally observed edge pedestal width, and that a steep pedestal must be accompanied by a self-consistent negative radial electric field well. It is also shown that a steep neoclassical pedestal can form naturally at a quiescent diverted edge as the particle source from the neutral penetration (and heat flux from the core plasma) is balanced by the sharply increasing convective ion loss toward the separatrix. The steep neoclassical pedestal and the strong radial electric field well are suppressed by an anomalous diffusion coefficient of a strength appropriate to an L-mode state; nonetheless, the ExB shearing rate increases rapidly with pedestal temperature. Additionally, the present study shows that a steep pedestal at the diverted edge acts as a cocurrent parallel momentum source

  8. Global performance enhancements via pedestal optimisation on ASDEX Upgrade

    NARCIS (Netherlands)

    Dunne, M.G.; Frassinetti, L.; Beurkens, M.N.A.; Cavedon, M.; Fietz, S.; Fischer, R.; Giannone, L.; Huijsmans, G.T.A.; Kurzan, B.; Laggner, F.; McCarhty, P.J.; McDermott, R.M.; Tardini, G.; Viezzer, E.; Willensdorfer, M.; Wolfrum, E.

    2017-01-01

    Results of experimental scans of heating power, plasma shape, and nitrogen content are presented, with a focus on global performance and pedestal alteration. In detailed scans at low triangularity, it is shown that the increase in stored energy due to nitrogen seeding stems from the pedestal. It is

  9. Compatibility of detached divertor operation with robust edge pedestal performance

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, A.W., E-mail: leonard@fusion.gat.com [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Makowski, M.A.; McLean, A.G. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Osborne, T.H.; Snyder, P.B. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States)

    2015-08-15

    The compatibility of detached radiative divertor operation with a robust H-mode pedestal is examined in DIII-D. A density scan produced low temperature plasmas at the divertor target, T{sub e} ⩽ 2 eV, with high radiation leading to a factor of ⩾4 drop in peak divertor heat flux. The cold radiative plasma was confined to the divertor and did not extend across the separatrix in X-point region. A robust H-mode pedestal was maintained with a small degradation in pedestal pressure at the highest densities. The response of the pedestal pressure to increasing density is reproduced by the EPED pedestal model. However, agreement of the EPED model with experiment at high density requires an assumption of reduced diamagnetic stabilization of edge Peeling–Ballooning modes.

  10. Predictive modeling of pedestal structure in KSTAR using EPED model

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hyunsun; Kim, J. Y. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Kwon, Ohjin [Department of Physics, Daegu University, Gyeongbuk 712-714 (Korea, Republic of)

    2013-10-15

    A predictive calculation is given for the structure of edge pedestal in the H-mode plasma of the KSTAR (Korea Superconducting Tokamak Advanced Research) device using the EPED model. Particularly, the dependence of pedestal width and height on various plasma parameters is studied in detail. The two codes, ELITE and HELENA, are utilized for the stability analysis of the peeling-ballooning and kinetic ballooning modes, respectively. Summarizing the main results, the pedestal slope and height have a strong dependence on plasma current, rapidly increasing with it, while the pedestal width is almost independent of it. The plasma density or collisionality gives initially a mild stabilization, increasing the pedestal slope and height, but above some threshold value its effect turns to a destabilization, reducing the pedestal width and height. Among several plasma shape parameters, the triangularity gives the most dominant effect, rapidly increasing the pedestal width and height, while the effect of elongation and squareness appears to be relatively weak. Implication of these edge results, particularly in relation to the global plasma performance, is discussed.

  11. Non-shoring construction for T/G pedestal beams

    International Nuclear Information System (INIS)

    Abe, T.

    1992-01-01

    The T/G pedestal construction work has been the critical path within the T/B construction work of BWR type nuclear power plant. In order to meet the requirement of shortening the construction period and improved in safety on a Turbine Building (T/B) construction work, Non-soring construction for T/G Pedestal Beams was developed. By applying this method to T/G pedestal construction work, we succeeded in shortening the T/B construction period and improvement in safety significantly. (author)

  12. Observation of ion scale fluctuations in the pedestal region during the edge-localized-mode cycle on the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, A.; Kramer, G. J.; Bell, R. E.; Guttenfelder, W.; LeBlanc, B. P.; Podesta, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Smith, D. R.; McKee, G. J. [Departments of Engineering Physics and Physics, University of Wisconsin, Madison, Wisconsin (United States); Maingi, R. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831 (United States); Fonck, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Departments of Engineering Physics and Physics, University of Wisconsin, Madison, Wisconsin (United States)

    2013-01-15

    Characterization of the spatial structure of turbulence fluctuations during the edge localized mode cycle in the pedestal region is reported. Using the beam emission spectroscopy and the correlation reflectometry systems, measurements show spatial structure-k{sub Up-Tack }{rho}{sub i}{sup ped}-ranging from 0.2 to 0.7 propagating in the ion diamagnetic drift direction at the pedestal top. These propagating spatial scales are found to be anisotropic and consistent with ion-scale microturbulence of the type ion temperature gradient and/or kinetic ballooning modes.

  13. Impact of impurity seeding and divertor conditions on transitions, pedestal structure and ELMs

    Science.gov (United States)

    Dunne, M. G.

    2017-02-01

    Future devices will require a high scrape-off later (SOL) density and impurity seeding to avoid high-Z sputtering. However, these operational parameters are not included in present-day scaling laws, making extrapolations to larger devices difficult. As such, understanding the physics of such effects is vital in order to design the operational scenarios most favorable to high fusion gain. This review presents the favorable lowering of L-H transition power by changing to metal walled devices and sumarises the effects currently thought to be responsible for how SOL geometry can play a role in determining this threshold. Experimental observations on changes to the pedestal structure with main ion fuelling and low-, medium-, and high-Z impurity seeding are presented. These results, from several devices, show that main ion fuelling or high density operation can result in a lower pedestal top pressure, and hence reduced stored energy, while impurity seeding can recover this lost pressure. Particular focus is given to nitrogen seeded discharges and the recovery of pedestal parameters (notably high {{T}\\text{e,\\text{ped}}} ) in JET and AUG since the changeover to metal walls in these devices. Lithium seeding is also emerging as a strong actuator in pedestal dynamics, with results ranging from a prolonged inter-ELM period to completely ELM-free scenarios on different devices. ELM dynamics are also presented in each section, with nitrogen seeding offering a probe into the structure of the ELM and demonstrating the difference between the initial ELM crash, likely due to a sharp MHD event, and a prolonged second phase, the origin of which remains unkown. Finally, modelling of the pedestal in impurity seeded scenarios reveals a common effect in the position of the density profile. Either through mode excitation near to the separatrix or an altered fuelling profile, seeding of impurities results in an inward shift of the density profile. This inward shift improves MHD stability

  14. Progress towards a predictive model for pedestal height in DIII-D

    International Nuclear Information System (INIS)

    Groebner, R.J.; Leonard, A.W.; Snyder, P.B.; Osborne, T.H.; Petty, C.C.; Maggi, C.F.; Fenstermacher, M.E.; Owen, L.W.

    2009-01-01

    Recent DIII-D pedestal studies provide improved characterization of pedestal scaling for comparison with models. A new pedestal model accurately predicts the maximum achieved pedestal width and height in type I ELMing discharges over a large range of DIII-D operational space, including ITER demonstration discharges. The model is a combination of the peeling-ballooning theory for the MHD stability limits on the pedestal with a simple pedestal width scaling in which the width is proportional to the square root of the pedestal poloidal beta. Width scalings based on the ion toroidal or poloidal gyroradius are much poorer descriptions of DIII-D data. A mass scaling experiment in H and D provides support for a poloidal beta scaling and is not consistent with an ion poloidal gyroradius scaling. Studies of pedestal evolution during the inter-ELM cycle provide evidence that both the pedestal width and height increase during pedestal buildup. Model studies with a 1D kinetic neutrals calculation show that the temporal increase in density width cannot be explained in terms of increased neutral penetration depth. These studies show a correlation of pedestal width with both the square root of the pedestal poloidal beta and the square root of the pedestal ion temperature during the pedestal buildup.

  15. MODEL OF THE TOKAMAK EDGE DENSITY PEDESTAL INCLUDING DIFFUSIVE NEUTRALS

    International Nuclear Information System (INIS)

    BURRELL, K.H.

    2003-01-01

    OAK-B135 Several previous analytic models of the tokamak edge density pedestal have been based on diffusive transport of plasma plus free-streaming of neutrals. This latter neutral model includes only the effect of ionization and neglects charge exchange. The present work models the edge density pedestal using diffusive transport for both the plasma and the neutrals. In contrast to the free-streaming model, a diffusion model for the neutrals includes the effect of both charge exchange and ionization and is valid when charge exchange is the dominant interaction. Surprisingly, the functional forms for the electron and neutral density profiles from the present calculation are identical to the results of the previous analytic models. There are some differences in the detailed definition of various parameters in the solution. For experimentally relevant cases where ionization and charge exchange rate are comparable, both models predict approximately the same width for the edge density pedestal

  16. The Effect of Plasma Shape on H-Mode Pedestal Characteristics on DIII-D

    International Nuclear Information System (INIS)

    T.H. Osborne; J.R. Ferron; R.J. Groebner; L.L. Lao; A.W. Leonard; R. Maingi; R.L. Miller; A.D. Turnbull; M.R. Wade; J.G. Watkins

    1999-01-01

    The characteristics of the H-mode are studied in discharges with varying triangularity and squareness. The pressure at the top of the H-mode pedestal increases strongly with triangularity primarily due to an increase in the margin by which the edge pressure gradient exceeds the ideal ballooning mode first stability limit. Two models are considered for how the edge may exceed the ballooning mode limit. In one model [1], access to the ballooning mode second stable regime allows the edge pressure gradient and associated bootstrap current to continue to increase until an edge localized, low toroidal mode number, ideal kink mode is destabilized. In the second model [2], the finite width of the H-mode transport barrier, and diamagnetic effects raise the pressure gradient limit above the ballooning mode limit. We observe a weak inverse dependence of the width of the H-mode transport barrier, Δ, on triangularity relative to the previously obtained [3] scaling Δ ∞ (β P PED ) 1/2 . The energy loss for Type I ELMs increases with triangularity in proportion to the pedestal energy increase. The temperature profile is found to respond stiffly to changes in T PED at low temperature, while at high temperature the response is additive. The response of the density profile is also found to play a role in the response of the total stored energy to changes in the W PED

  17. Impact of the pedestal plasma density on dynamics of edge localized mode crashes and energy loss scaling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. Q., E-mail: xxu@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ma, J. F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States); Li, G. Q. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)

    2014-12-15

    The latest BOUT++ studies show an emerging understanding of dynamics of edge localized mode (ELM) crashes and the consistent collisionality scaling of ELM energy losses with the world multi-tokamak database. A series of BOUT++ simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan. Linear results demonstrate that as the pedestal collisionality decreases, the growth rate of the peeling-ballooning modes decreases for high n but increases for low n (1 < n < 5), therefore the width of the growth rate spectrum γ(n) becomes narrower and the peak growth shifts to lower n. Nonlinear BOUT++ simulations show a two-stage process of ELM crash evolution of (i) initial bursts of pressure blob and void creation and (ii) inward void propagation. The inward void propagation stirs the top of pedestal plasma and yields an increasing ELM size with decreasing collisionality after a series of micro-bursts. The pedestal plasma density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. The critical trend emerges as a transition (1) linearly from ballooning-dominated states at high collisionality to peeling-dominated states at low collisionality with decreasing density and (2) nonlinearly from turbulence spreading dynamics at high collisionality into avalanche-like dynamics at low collisionality.

  18. DSS 13 phase 2 pedestal room microwave layout

    Science.gov (United States)

    Cwik, T.; Chen, J. C.

    1991-01-01

    The design and predicted performance is described of the microwave layout for three band operation of the beam waveguide antenna Deep Space Station 13. Three pedestal room microwave candidate layout designs were produced for simultaneous X/S and X/Ka band operation. One of the three designs was chosen based on given constraints, and for this design the microwave performance was estimated.

  19. Placed on a Pedestal: Famous Faces in Clay

    Science.gov (United States)

    Walkup, Nancy

    2010-01-01

    Artists have created portraits of people for thousands of years. In sculpture, a portrait of a person's face often includes the neck and part of the shoulders and chest. These artworks are called portrait busts. In this article, the author describes how her fifth-grade students created clay portrait busts on pedestal columns. The objectives are…

  20. Control of bootstrap current in the pedestal region of tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Shaing, K. C. [Institute for Space and Plasma Sciences, National Cheng Kung University, Tainan City 70101, Taiwan (China); Department of Engineering Physics, University of Wisconsin, Madison, Wisconsin 53796 (United States); Lai, A. L. [Institute for Space and Plasma Sciences, National Cheng Kung University, Tainan City 70101, Taiwan (China)

    2013-12-15

    The high confinement mode (H-mode) plasmas in the pedestal region of tokamaks are characterized by steep gradient of the radial electric field, and sonic poloidal U{sub p,m} flow that consists of poloidal components of the E×B flow and the plasma flow velocity that is parallel to the magnetic field B. Here, E is the electric field. The bootstrap current that is important for the equilibrium, and stability of the pedestal of H-mode plasmas is shown to have an expression different from that in the conventional theory. In the limit where ‖U{sub p,m}‖≫ 1, the bootstrap current is driven by the electron temperature gradient and inductive electric field fundamentally different from that in the conventional theory. The bootstrap current in the pedestal region can be controlled through manipulating U{sub p,m} and the gradient of the radial electric. This, in turn, can control plasma stability such as edge-localized modes. Quantitative evaluations of various coefficients are shown to illustrate that the bootstrap current remains finite when ‖U{sub p,m}‖ approaches infinite and to provide indications how to control the bootstrap current. Approximate analytic expressions for viscous coefficients that join results in the banana and plateau-Pfirsch-Schluter regimes are presented to facilitate bootstrap and neoclassical transport simulations in the pedestal region.

  1. Kinetic neoclassical transport in the H-mode pedestal

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, D. J.; Chang, C. S.; Ku, S.; Grierson, B. A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08540 (United States); Burrell, K. H.; Grassie, J. S. de [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

    2014-07-15

    Multi-species kinetic neoclassical transport through the QH-mode pedestal and scrape-off layer on DIII-D is calculated using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. Quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density, and orthogonal measurements of impurity temperature and flow profiles is achieved by adding random-walk particle diffusion to the guiding-center drift motion. The radial electric field (E{sub r}) that maintains ambipolar transport across flux surfaces and to the wall is computed self-consistently on closed and open magnetic field lines and is in excellent agreement with experiment. The E{sub r} inside the separatrix is the unique solution that balances the outward flux of thermal tail deuterium ions against the outward neoclassical electron flux and inward pinch of impurity and colder deuterium ions. Particle transport in the pedestal is primarily due to anomalous transport, while the ion heat and momentum transport are primarily due to the neoclassical transport. The full-f treatment quantifies the non-Maxwellian energy distributions that describe a number of experimental observations in low-collisionallity pedestals on DIII-D, including intrinsic co-I{sub p} parallel flows in the pedestal, ion temperature anisotropy, and large impurity temperatures in the scrape-off layer.

  2. Arbitrary poloidal gyroradius effects in tokamak pedestals and transport barriers

    International Nuclear Information System (INIS)

    Kagan, Grigory; Catto, Peter J

    2008-01-01

    A technique is developed and applied for analyzing pedestal and internal transport barrier (ITB) regions in a tokamak by formulating a special version of gyrokinetics. In contrast to typical gyrokinetic treatments, canonical angular momentum is taken as the gyrokinetic radial variable rather than the radial guiding center location. Such an approach allows strong radial plasma gradients to be treated, while retaining zonal flow and neoclassical (including orbit squeezing) behavior and the effects of turbulence. The new, nonlinear gyrokinetic variables are constructed to higher order than is typically the case. The nonlinear gyrokinetic equation obtained is capable of handling such problems as collisional zonal flow damping with radial wavelengths comparable to the ion poloidal gyroradius, as well as zonal flow and neoclassical transport in the pedestal or ITB. This choice of gyrokinetic variables allows the toroidally rotating Maxwellian solution of the isothermal tokamak limit to be recovered. More importantly, we prove that a physically acceptable solution for the lowest order ion distribution function in the banana regime anywhere in a tokamak and, in particular, in the pedestal must be nearly this same isothermal Maxwellian solution. That is, the ion temperature variation scale must be much greater than the poloidal ion gyroradius. Consequently, in the banana regime the background radial ion temperature profile cannot have a pedestal similar to that of plasma density

  3. Threshold for sweepout from pedestal region of Mark III containment

    International Nuclear Information System (INIS)

    Sienicki, J.J.; Spencer, B.W.

    1984-01-01

    The assessment of the consequences of highly unlikely severe accident sequences in boiling water reactors includes those sequences in which molten corium is postulated to meltthrough the reactor pressure vessel (RPV) lower head and enter the pedestal region beneath the vessel. If localized melt-through of the reactor vessel occurs at elevated primary system pressure, the ejection of molten corium from the vessel will be followed by a blowdown of steam and hydrogen. The gases flowing from the breached vessel constitute a source of driving forces capable of dispersing corium from the pedestal into other parts of the containment. The extent of the gas blowdown-driven sweepout process depends upon a number of factors including the primary system pressure at melt through, breach flow area, overall blowdown timescale, and the specific pedestal/containment geometry. A model is presented to predict whether or not the conditions of gas flow from the failed RPV are sufficient to cause sweepout of corium and/or water from the pedestal. The model is shown to predict the onset of sweepout in scale model, simulant material experiments and is applied to the investigation of sweepout in the full-size reactor system

  4. Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

    Science.gov (United States)

    Stefanikova, E.; Frassinetti, L.; Saarelma, S.; Loarte, A.; Nunes, I.; Garzotti, L.; Lomas, P.; Rimini, F.; Drewelow, P.; Kruezi, U.; Lomanowski, B.; de la Luna, E.; Meneses, L.; Peterka, M.; Viola, B.; Giroud, C.; Maggi, C.; contributors, JET

    2018-05-01

    The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called relative shift has an impact on the pedestal magnetohydrodynamic (MHD) stability and hence on the pedestal height (Osborne et al 2015 Nucl. Fusion 55 063018). The present work studies the effect of the relative shift on pedestal stability of JET ITER-like wall (JET-ILW) baseline low triangularity (δ) unseeded plasmas, and similar JET-C discharges. As shown in this paper, the increase of the pedestal relative shift is correlated with the reduction of the normalized pressure gradient, therefore playing a strong role in pedestal stability. Furthermore, JET-ILW tends to have a larger relative shift compared to JET carbon wall (JET-C), suggesting a possible role of the plasma facing materials in affecting the density profile location. Experimental results are then compared with stability analysis performed in terms of the peeling-ballooning model and with pedestal predictive model EUROPED (Saarelma et al 2017 Plasma Phys. Control. Fusion). Stability analysis is consistent with the experimental findings, showing an improvement of the pedestal stability, when the relative shift is reduced. This has been ascribed mainly to the increase of the edge bootstrap current, and to minor effects related to the increase of the pedestal pressure gradient and narrowing of the pedestal pressure width. Pedestal predictive model EUROPED shows a qualitative agreement with experiment, especially for low values of the relative shift.

  5. Isotope and mixture effects on neoclassical transport in the pedestal

    Science.gov (United States)

    Pusztai, Istvan; Buller, Stefan; Omotani, John T.; Newton, Sarah L.

    2017-10-01

    The isotope mass scaling of the energy confinement time in tokamak plasmas differs from gyro-Bohm estimates, with implications for the extrapolation from current experiments to D-T reactors. Differences in mass scaling in L-mode and various H-mode regimes suggest that the isotope effect may originate from the pedestal. In the pedestal, sharp gradients render local diffusive estimates invalid, and global effects due to orbit-width scale profile variations have to be taken into account. We calculate neoclassical cross-field fluxes from a radially global drift-kinetic equation using the PERFECT code, to study isotope composition effects in density pedestals. The relative reduction to the peak heat flux due to global effects as a function of the density scale length is found to saturate at an isotope-dependent value that is larger for heavier ions. We also consider D-T and H-D mixtures with a focus on isotope separation. The ability to reproduce the mixture results via single-species simulations with artificial ``DT'' and ``HD'' species has been considered. These computationally convenient single ion simulations give a good estimate of the total ion heat flux in corresponding mixtures. Funding received from the International Career Grant of Vetenskapsradet (VR) (330-2014-6313) with Marie Sklodowska Curie Actions, Cofund, Project INCA 600398, and Framework Grant for Strategic Energy Research of VR (2014-5392).

  6. Scaling studies of the H-mode pedestal

    International Nuclear Information System (INIS)

    Groebner, R.J.; Osborne, T.H.

    1998-01-01

    The structure and scaling of the H-mode pedestal are examined for discharges in the DIII-D tokamak. For typical conditions, the pedestal values of the ion and electron temperatures T i and T e are comparable. Measurements of main ion and C 6+ profiles indicate that the ion pressure gradient in the barrier is 50%--100% of the electron pressure gradient for deuterium plasmas. The magnitude of the pressure gradient in the barrier often exceeds the predictions of infinite-n ballooning mode theory by a factor of two. Moreover, via the bootstrap current, the finite pressure gradient acts to entirely remove ballooning stability limits for typical discharges. For a large dataset, the width of the pressure barrier δ is best described by the dimensionless scaling δ/R ∝ (β pol ped ) 0.4 where (β pol ped ) is the pedestal value of poloidal beta and R is the major radius. Scalings based on the poloidal ion gyroradius or the edge density gradient do not adequately describe overall trends in the data set and the propagation of the pressure barrier observed between edge-localized modes. The width of the T i barrier is quite variable and is not a good measure of the width of the pressure barrier

  7. Effect of PFC recycling conditions on JET pedestal density

    International Nuclear Information System (INIS)

    Wiesen, S.; Brezinsek, S.; Dittmar, T.; Matveev, D.; Harting, D.; De la Luna, E.; Schmid, K.

    2016-01-01

    There is experimental evidence that the pedestal dynamics in type-I ELMy H-mode discharges is significantly affected by a change in the recycling conditions at the tungsten plasma-facing components (W-PFCs) after an ELM event. The integrated code JINTRAC has been employed to assess the impact of recycling conditions during type-I ELMs in JET ITER-like wall H-mode discharges. By employing a heuristic approach, a model to mimic the physical processes leading to formation and release (i.e. outgassing) of finite near-surface fuel reservoirs in W-PFCs has been implemented into the EDGE2D-EIRENE plasma-wall interaction code being part of JINTRAC. As main result it is shown, that a delay in the density pedestal build-up after an ELM event can be provoked by reduced recycling induced by depleted W-PFC particle near-surface reservoirs. However the pedestal temperature evolution is barely affected by the change in recycling parameters suggesting that the presented model is incomplete. (copyright 2016 The Authors. Contributions to Plasma Physics published by Wiley-VCH Verlag GmbH and Co. KGaA Weinheim. This)

  8. Scaling of H-mode pedestal characteristics in DIII-D and C-Mod

    International Nuclear Information System (INIS)

    Granetz, R.S.; Boivin, R.L.; Osborne, T.H.

    1999-01-01

    Since the H-mode edge pedestal effectively sets the boundary conditions for energy transport throughout the core, a better understanding of the pedestal region is necessary in order to fully predict H-mode performance. Pedestal characteristics in the DIII-D and Alcator C-Mod tokamaks are described, and scalings of the pedestal width with various plasma parameters are shown. The pedestal width in both tokamaks varies in an inverse sense with plasma current, and is independent of toroidal field. Other similarities, as well as differences, are discussed. It is also found that the pedestal widths of the various physical quantities involved (T e , T i , n e , n i ) may be different. (author)

  9. The stabilizing effect of core pressure on the edge pedestal in MAST plasmas

    International Nuclear Information System (INIS)

    Chapman, I.T.; Simpson, J.; Saarelma, S.; Kirk, A.; O'Gorman, T.; Scannell, R.

    2015-01-01

    The pedestal pressure measured in Mega Ampere Spherical Tokamak plasmas has been shown to increase as the global plasma pressure increases. By deliberately suppressing the transition into the high-confinement regime, the core plasma pressure was systematically altered at the time of the first edge localized mode. Stability analysis shows that the enhanced Shafranov shift at higher core pressure stabilizes the ballooning modes driven by the pedestal pressure gradient, consequently allowing the pedestal to reach higher pressures. (paper)

  10. Temporal evolution of H-mode pedestal in DIII-D

    International Nuclear Information System (INIS)

    Groebner, R.J.; Osborne, T.H.; Leonard, A.W.; Fenstermacher, M.E.

    2009-01-01

    The temporal evolution of pedestal parameters is examined in the initial edge localized mode (ELM)-free phase and inter-ELM phases of H-mode discharges in the DIII-D tokamak. These discharges are heated by deuterium neutral beam injection and achieve type-I ELMing conditions. Pedestal parameters exhibit qualitatively similar behaviour in both the ELM-free and inter-ELM phases. There is a trend for the widths and heights of pedestals for electron density, temperature and pressure to increase during these phases; the increase in width is most pronounced in the density and least pronounced in electron temperature. Near the separatrix, the ion temperature achieves higher values but a flatter profile as compared with the electron temperature. Higher heating powers lead to a faster evolution of the pedestal and to a shorter period until the onset of an ELM. For sufficiently long ELM-free or inter-ELM periods, some parameters, particularly gradients, approach a steady state. However, a simultaneous steady state in all parameters is not observed. The simultaneous increase in density width and pedestal density is opposite to the predictions of a simple model, which predicts that the density width is set by neutral penetration. Thus, additional physics must be added to the simple model to provide a more general description of pedestal behaviour. However, the barrier growth is qualitatively consistent with time-dependent theoretical models that predict a self-consistent temporal growth of the pedestal due to E x B shearing effects. In addition, an approximate linear correlation is observed between the density width and the square root of the pedestal ion temperature and also between the density width and the square root of the pedestal beta poloidal. These pedestal studies suggest that a complete model of the pedestal width in type-I ELMing discharges must be time dependent, include transport physics during inter-ELM periods and include the limits to pedestal evolution

  11. Structural Modeling and Analysis on Dynamic Characteristics of Antenna Pedestal in Airborne SAR

    Directory of Open Access Journals (Sweden)

    He Li-ping

    2012-06-01

    Full Text Available Finite element modeling and structural dynamic characteristics of antenna pedestal in airborne SAR were studied in this paper. The Finite element model of antenna pedestal in airborne SAR was set up on the basis of structural dynamic theory, then, the key technologies of dynamic simulation were pointed out, and the modal analysis and transient analysis were carried out. Simulation results show that the dynamic characteristics of antenna pedestal in airborne SAR can meet the requirements of servo bandwidth and structural strength. The fast finite element modeling and simulation method proposed in this paper are of great significance to the weight reducing design of antenna pedestal in airborne SAR.

  12. Global gyrokinetic simulation of Tokamak edge pedestal instabilities.

    Science.gov (United States)

    Wan, Weigang; Parker, Scott E; Chen, Yang; Yan, Zheng; Groebner, Richard J; Snyder, Philip B

    2012-11-02

    Global electromagnetic gyrokinetic simulations show the existence of near threshold conditions for both a high-n kinetic ballooning mode (KBM) and an intermediate-n kinetic version of peeling-ballooning mode (KPBM) in the edge pedestal of two DIII-D H-mode discharges. When the magnetic shear is reduced in a narrow region of steep pressure gradient, the KPBM is significantly stabilized, while the KBM is weakly destabilized and hence becomes the most-unstable mode. Collisions decrease the KBM's critical β and increase the growth rate.

  13. Comparison of H-mode pedestals in different confinement regimes in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Groebner, R J [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States); Leonard, A W [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States); Luce, T C [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States); Fenstermacher, M E [Lawrence Livermore National Laboratory, Livermore, California (United States); Jackson, G L [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States); Osborne, T H [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States); Thomas, D M [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States); Wade, M R [General Atomics, PO Box 85608, San Diego, California, 92186-5608 (United States)

    2006-05-15

    A survey of global performance parameters and their correlation with pedestal parameters is performed for standard H-mode, QH-mode and the enhanced confinement regimes of VH-mode, hybrid and advanced tokamak in the DIII-D tokamak. This study shows that there is a trend for global confinement quality or global beta to increase as the pedestal electron pressure or beta increases. However, there are also improvements in core confinement and beta, observed at fixed pedestal pressure or beta, which indicate that factors other than pedestal parameters also contribute to the best core performance. Several other pedestal structure parameters are found to be similar among these regimes. The scale lengths for electron pressure in the pedestal are in the range 0.8-1.6 cm at the outer midplane, most {eta}{sub e} values are in the range 1-3 in the middle of the T{sub e} pedestal and the T{sub e} and n{sub e} pedestals tend to penetrate the same distance into the plasma.

  14. Edge-localized mode avoidance and pedestal structure in I-mode plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Walk, J. R., E-mail: jrwalk@psfc.mit.edu; Hughes, J. W.; Hubbard, A. E.; Terry, J. L.; Whyte, D. G.; White, A. E.; Baek, S. G.; Reinke, M. L.; Theiler, C.; Churchill, R. M.; Rice, J. E. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139-4307 (United States); Snyder, P. B.; Osborne, T. [General Atomics, San Diego, CA 92186-5608 (United States); Dominguez, A [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Cziegler, I. [UCSD Center for Momentum Transport and Flow Organization, La Jolla, CA 92093-0417 (United States)

    2014-05-15

    I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle P{sub net}/n{sup ¯}{sub e}, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of P{sub net}/n{sup ¯}{sub e}. This is consistent with targets for increased performance in I-mode, elevating pedestal β{sub p} and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs

  15. Ekspedeerimisfirmade TOP

    Index Scriptorium Estoniae

    2008-01-01

    Ekspedeerimisfirmade TOP 57. Vt. samas: Tanel Raig. Majandus kukutab ekspedeerimisturgu. Diagramm: Väliskaubanduse statistika; Katrin Raie. Ekspedeerijad hakkavad rohkem koostööle rõhuma. Kommenteerib Jaan Lepp; Müügitulu TOP 10; Müügitulu kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Eestis registreeritud Vene hiiglane; Ekspedeerimisturu kasumiliider kaotas 20 miljonit; Küsimustele vastab OÜ Contimer juht Dmitri Redkin

  16. Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

    Science.gov (United States)

    Komm, M.; Bílková, P.; Aftanas, M.; Berta, M.; Böhm, P.; Bogár, O.; Frassinetti, L.; Grover, O.; Háček, P.; Havlicek, J.; Hron, M.; Imríšek, M.; Krbec, J.; Mitošínková, K.; Naydenkova, D.; Pánek, R.; Peterka, M.; Snyder, P. B.; Stefanikova, E.; Stöckel, J.; Sos, M.; Urban, J.; Varju, J.; Vondráček, P.; Weinzettl, V.; the COMPASS Team

    2017-05-01

    First systematic measurements of pedestal structure during Ohmic and NBI-assisted Type I ELMy H-modes were performed on the COMPASS tokamak in two dedicated experimental campaigns during 2015 and 2016. By adjusting the NBI heating and a toroidal magnetic field, the electron pedestal temperature was increased from 200 eV up to 300 eV, which allowed reaching pedestal collisionality ν \\text{ped}\\ast   <  1 at q95 ~3. COMPASS has approached conditions for the Identity experiment done at JET & DIII-D, complementing the range of scanned ρ \\text{ped}\\ast . The pedestal pressure was successfully reproduced by the EPED model. The dependence of pedestal pressure width on ν \\text{ped}\\ast and β \\text{ped ~ }\\text{pol} is discussed.

  17. Theory of Rapid Formation of Pedestal and Pedestal width due to Anomalous Particle Pinch in the Edge of H-mode Discharges

    Energy Technology Data Exchange (ETDEWEB)

    Kaw, P.K., E-mail: kaw@ipr.res.in [Institute for Plasma Research, Bhat (India); Singh, R. [Institute for Plasma Research, Bhat (India); ITER Organization, Saint Paul-lez-Durance [France; Nordman, H. [Chamlers Institute of Technology, Goteborg (Sweden); Garbet, X.; Bourdelle, C. [CEA, Saint Paul-lez-Durance (France); Campbell, D.; Loarte, A.; Bora, D. [ITER Organization, Saint Paul-lez-Durance (France)

    2012-09-15

    Full text: A theory based on a turbulent particle pinch is proposed to explain the rapid formation of sharp density gradients in tokamak edge plasmas, in particular the pedestal region. The inward radial particle flux in the pedestal results from the interaction between small scale electron temperature gradient driven (ETG) turbulence and self-consistently formed 'electron geodesic acoustic modes' (el-GAMs). To address this phenomenon, the el-GAM modulational instability driven by the ETG turbulence background is studied. The ETG level of fluctuations and particle pinch are estimated through the back reaction of eGAMs on ETG turbulence. It is found that the particle pinch is quite sensitive to magnetic shear, safety factor, ratio of electron to ion temperatures and atomic mass number. In the absence of particle source in the pedestal, the density gradient length scale, of the order of the pedestal width, is estimated. It is shown that it is proportional to the major radius, up to some dependence on the poloidal beta. Moreover it does not depend on the normalized gyro-radius. This scaling agrees with DIII-D and JET similarity experiments. This dependence is favorable when extrapolated to the pedestal width in ITER in spite of its low normalized gyro radius. It is also shown that the density scale length becomes sharper by increasing the magnetic shear. A new H-mode pedestal pressure scaling is derived assuming that the pressure gradient is limited by the ballooning instability. (author)

  18. Differences in the H-mode pedestal width of temperature and density

    International Nuclear Information System (INIS)

    Schneider, P A; Wolfrum, E; Günter, S; Kurzan, B; Lackner, K; Zohm, H; Groebner, R J; Osborne, T H; Ferron, J R; Snyder, P B; Beurskens, M N A; Dunne, M G

    2012-01-01

    A pedestal database was built using data from type-I ELMy H-modes of ASDEX Upgrade, DIII-D and JET. ELM synchronized pedestal data were analysed with the two-line method. The two-line method is a bilinear fit which shows better reproducibility of pedestal parameters than a modified hyperbolic tangent fit. This was tested with simulated and experimental data. The influence of the equilibrium reconstruction on pedestal parameters was investigated with sophisticated reconstructions from CLISTE and EFIT including edge kinetic profiles. No systematic deviation between the codes could be observed. The flux coordinate system is influenced by machine size, poloidal field and plasma shape. This will change the representation of the width in different coordinates, in particular, the two normalized coordinates Ψ N and r/a show a very different dependence on the plasma shape. The scalings derived for the pedestal width, Δ, of all machines suggest a different scaling for the electron temperature and the electron density. Both cases show similar dependence with machine size, poloidal magnetic field and pedestal electron temperature and density. The influence of ion temperature and toroidal magnetic field is different on each of Δ T e and Δ n e . In dimensionless form the density pedestal width in Ψ N scales with ρ 0.6 i* , the temperature pedestal width with β p,ped 0.5 . Both widths also show a strong correlation with the plasma shape. The shape dependence originates from the coordinate transformation and is not visible in real space. The presented scalings predict that in ITER the temperature pedestal will be appreciably wider than the density pedestal. (paper)

  19. Control of edge localized modes by pedestal deposited impurity in the HL-2A tokamak

    Science.gov (United States)

    Zhang, Y. P.; Mazon, D.; Zou, X. L.; Zhong, W. L.; Gao, J. M.; Zhang, K.; Sun, P.; Dong, C. F.; Cui, Z. Y.; Liu, Yi; Shi, Z. B.; Yu, D. L.; Cheng, J.; Jiang, M.; Xu, J. Q.; Isobe, M.; Xiao, G. L.; Chen, W.; Song, S. D.; Bai, X. Y.; Zhang, P. F.; Yuan, G. L.; Ji, X. Q.; Li, Y. G.; Zhou, Y.; Delpech, L.; Ekedahl, A.; Giruzzi, G.; Hoang, T.; Peysson, Y.; Song, X. M.; Song, X. Y.; Li, X.; Ding, X. T.; Dong, J. Q.; Yang, Q. W.; Xu, M.; Duan, X. R.; Liu, Y.; the HL-2A Team

    2018-04-01

    Effect of the pedestal deposited impurity on the edge-localized mode (ELM) behaviour has been observed and intensively investigated in the HL-2A tokamak. Impurities have been externally seeded by a newly developed laser blow-off (LBO) system. Both mitigation and suppression of ELMs have been realized by LBO-seeded impurity. Measurements have shown that the LBO-seeded impurity particles are mainly deposited in the pedestal region. During the ELM mitigation phase, the pedestal density fluctuation is significantly increased, indicating that the ELM mitigation may be achieved by the enhancement of the pedestal transport. The transition from ELM mitigation to ELM suppression was triggered when the number of the LBO-seeded impurity exceeds a threshold value. During the ELM suppression phase, a harmonic coherent mode (HCM) is excited by the LBO-seeded impurity, and the pedestal density fluctuation is significantly decreased, the electron density is continuously increased, implying that HCM may reduce the pedestal turbulence, suppress ELMs, increase the pedestal pressure, thus extending the Peeling-Ballooning instability limit. It has been found that the occurance of the ELM mitigation and ELM suppression closely depends on the LBO laser spot diameter.

  20. BURNING PLASMA PROJECTIONS USING DRIFT WAVE TRANSPORT MODELS AND SCALINGS FOR THE H-MODE PEDESTAL

    International Nuclear Information System (INIS)

    KINSEY, J.E.; ONJUN, T.; BATEMAN, G.; KRITZ, A.; PANKIN, A.; STAEBLER, G.M.; WALTZ, R.E.

    2002-01-01

    OAK-B135 The GLF23 and Multi-Mode (MM95) transport models are used along with a model for the H-mode pedestal to predict the fusion performance for the ITER, FIRE, and IGNITOR tokamak designs. The drift-wave predictive transport models reproduce the core profiles in a wide variety of tokamak discharges, yet they differ significantly in their response to temperature gradient (stiffness). Recent gyro-kinetic simulations of ITG/TEM and ETG modes motivate the renormalization of the GLF23 model. The normalizing coefficients for the ITG/TEM modes are reduced by a factor of 3.7 while the ETG mode coefficient is increased by a factor of 4.8 in comparison with the original model. A pedestal temperature model is developed for type I ELMy H-mode plasmas based on ballooning mode stability and a theory-motivated scaling for the pedestal width. In this pedestal model, the pedestal density is proportional to the line-averaged density and the pedestal temperature is inversely related to the pedestal density

  1. Structure, stability and ELM dynamics of the H-mode pedestal in DIII-D

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Leonard, A.W.; Osborne, T.H.

    2005-01-01

    Experiments are described that have increased understanding of the transport and stability physics that set the H-mode edge pedestal width and height, determine the onset of Type-I edge localized modes (ELMs), and produce the nonlinear dynamics of the ELM perturbation in the pedestal and scrape-off layer (SOL). Predictive models now exist for the n e pedestal profile and the p e height at the onset of Type-I ELMs, and progress has been made toward predictive models of the T e pedestal width and nonlinear ELM evolution. Similarity experiments between DIII-D and JET suggested that neutral penetration physics dominates in the relationship between the width and height of the n e pedestal while plasma physics dominates in setting the T e pedestal width. Measured pedestal conditions including edge current at ELM onset agree with intermediate-n peeling-ballooning (P-B) stability predictions. Midplane ELM dynamics data show the predicted (P-B) structure at ELM onset, large rapid variations of the SOL parameters, and fast radial propagation in later phases, similar to features in nonlinear ELM simulations. (author)

  2. A unified treatment of kinetic effects in a tokamak pedestal

    International Nuclear Information System (INIS)

    Catto, Peter J; Landreman, Matt; Kagan, Grigory; Pusztai, Istvan

    2011-01-01

    We consider the effects of a finite pedestal radial electric field on ion orbits using a unified approach. We then employ these modified orbit results to retain finite E x B drift departures from flux surfaces in an improved drift-kinetic equation. The procedure allows us to make a clear distinction between transit averages and flux surface averages when solving this kinetic equation. The technique outlined here is intended to clarify and unify recent evaluations of the banana regime decrease and plateau regime alterations in the ion heat diffusivity; the reduction and possible reversal of the poloidal flow in the banana regime, and its augmentation in the plateau regime; the increase in the bootstrap current; and the enhancement of the residual zonal flow regulation of turbulence.

  3. Global simulation of edge pedestal micro-instabilities

    Science.gov (United States)

    Wan, Weigang; Parker, Scott; Chen, Yang

    2011-10-01

    We study micro turbulence of the tokamak edge pedestal with global gyrokinetic particle simulations. The simulation code GEM is an electromagnetic δf code. Two sets of DIII-D experimental profiles, shot #131997 and shot #136051 are used. The dominant instabilities appear to be two kinds of modes both propagating in the electron diamagnetic direction, with comparable linear growth rates. The low n mode is at the Alfven frequency range and driven by density and ion temperature gradients. The high n mode is driven by electron temperature gradient and has a low real frequency. A β scan shows that the low n mode is electromagnetic. Frequency analysis shows that the high n mode is sometimes mixed with an ion instability. Experimental radial electric field is applied and its effects studied. We will also show some preliminary nonlinear results. We thank R. Groebner, P. Snyder and Y. Zheng for providing experimental profiles and helpful discussions.

  4. Characteristics of edge pedestals in LHW and NBI heated H-mode plasmas on EAST

    Science.gov (United States)

    Zang, Q.; Wang, T.; Liang, Y.; Sun, Y.; Chen, H.; Xiao, S.; Han, X.; Hu, A.; Hsieh, C.; Zhou, H.; Zhao, J.; Zhang, T.; Gong, X.; Hu, L.; Liu, F.; Hu, C.; Gao, X.; Wan, B.; the EAST Team

    2016-10-01

    By using the recently developed Thomson scattering diagnostic, the pedestal structure of the H-mode with neutral beam injection (NBI) or/and lower hybrid wave (LHW) heating on EAST (Experimental Advanced Superconducting Tokamak) is analyzed in detail. We find that a higher ratio of the power of the NBI to the total power of the NBI and the lower hybrid wave (LHW) will produce a large and regular different edge-localized mode (ELM), and a lower ratio will produce a small and irregular ELM. The experiments show that the mean pedestal width has good correlation with β \\text{p,\\text{ped}}0.5 , The pedestal width appears to be wider than that on other similar machines, which could be due to lithium coating. However, it is difficult to draw any conclusion of correlation between ρ * and the pedestal width for limited ρ * variation and scattered distribution. It is also found that T e/\

  5. Cost reduction for large turbine generator Pedestal in high seismic zone

    International Nuclear Information System (INIS)

    Sawhney, P.S.; Irani, P.; Pusheck, B.N.

    1985-01-01

    Turbine Generator Pedestals have generally been designed using reinforced concrete. For present day large turbine generators (1100 MWe class and above) with tall (about 80 feet) pedestals, the amount of reinforcing steel becomes quite large, especially for plants in high seismic zones. With the prime objective of cost reduction, an approach using steel/concrete composite design has been studied for a large BWR Turbine Generator pedestal with 0.3g peak ground acceleration. Large prefabricated steel modules were adopted for composite design and simplified construction. Design was based on the ACI and AISC codes. Costs and schedules were developed and compared with those for a conventionally designed reinforced concrete pedestal. Composite design was found to give considerable cost and schedule advantage over the conventional reinforced concrete design

  6. Ion orbit loss and pedestal width of H-mode tokamak plasmas in limiter geometry

    International Nuclear Information System (INIS)

    Xiao Xiaotao; Liu Lei; Zhang Xiaodong; Wang Shaojie

    2011-01-01

    A simple analytical model is proposed to analyze the effects of ion orbit loss on the edge radial electric field in a tokamak with limiter configuration. The analytically predicted edge radial electric field is consistent with the H-mode experiments, including the width, the magnitude, and the well-like shape. This model provides an explanation to the H-mode pedestal structure. Scaling of the pedestal width based on this model is proposed.

  7. Effect of pedestal fluctuation on ELM frequency in the EAST tokamak

    Science.gov (United States)

    Zhong, F. B.; Zhang, T.; Liu, Z. X.; Qu, H.; Liu, H. Q.; Li, G. Q.; Liu, Y.; Gao, W.; Duan, Y. M.; Yang, Y.; Zeng, L.; Xiang, H. M.; Geng, K. N.; Wen, F.; Zhang, S. B.; Gao, X.; the EAST Team

    2018-05-01

    The dependence of ELM frequency on heating power has been studied on the Experimental Advanced Superconducting Tokamak (EAST). It is found that the ELM frequency (f ELM) generally increases with the power through separatrix (P sep), indicating type-I ELM in these plasmas. However, there are two data points, named ‘abnormal ELM’ in the present paper, which have much lower f ELM than the ‘normal ELM’, while both types of ELM have similar ELM energy losses. The ‘abnormal ELM’ occurs at a phase with increased radiation power due to metal impurity influx events. The increased radiation power cannot explain the much lower f ELM for ‘abnormal ELM’, since the reduction of P sep is weaker than proportional to the observed reduction of the ELM frequency. The ‘abnormal ELM’ feature can be attributed to the enhanced amplitude of a coherent mode in the pedestal region. Comparing the pedestal evolutions for the two types of ELM with similar separatrix power P sep, it is actually found that the more pronounced pedestal coherent mode in the plasma with ‘abnormal ELM’ leads to a slower pressure pedestal recovery during the inter-ELM phase. This experimental result implies that the physical mechanism for ‘abnormal ELM’ is that the more pronounced pedestal fluctuation induces larger outward transport, slows down the pedestal evolution and leads to longer inter-ELM phase, i.e. lower ELM frequency.

  8. Volcanic risk

    International Nuclear Information System (INIS)

    Rancon, J.P.; Baubron, J.C.

    1995-01-01

    This project follows the previous multi-disciplinary studies carried out by the French Bureau de Recherches Geologiques et Minieres (BRGM) on the two active volcanoes of the French lesser Antilles: Mt Pelee (Martinique) and Soufriere (Guadeloupe) for which geological maps and volcanic risk studies have been achieved. The research program comprises 5 parts: the study of pyroclastic deposits from recent eruptions of the two volcanoes for a better characterization of their eruptive phenomenology and a better definition of crisis scenarios; the study of deposits and structures of active volcanoes from Central America and the study of eruptive dynamics of andesite volcanoes for a transposition to Antilles' volcanoes; the starting of a methodological multi-disciplinary research (volcanology, geography, sociology...) on the volcanic risk analysis and on the management of a future crisis; and finally, the development of geochemical survey techniques (radon, CO 2 , H 2 O) on active volcanoes of Costa-Rica and Europe (Fournaise, Furnas, Etna) and their application to the Soufriere. (J.S.). 9 refs., 3 figs

  9. ELMs and constraints on the H-mode pedestal: A model based on peeling-ballooning modes

    International Nuclear Information System (INIS)

    Snyder, P.B.; Ferron, J.R.; Wilson, H.R.

    2003-01-01

    We propose a model for Edge Localized Modes (ELMs) and pedestal constraint based upon theoretical analysis of instabilities which can limit the pedestal height and drive ELMs. The sharp pressure gradients, and resulting bootstrap current, in the pedestal region provide free energy to drive peeling and ballooning modes. The interaction of peeling-ballooning coupling, ballooning mode second stability, and finite-Larmor-radius effects results in coupled peeling-ballooning modes of intermediate wavelength generally being the limiting instability. A highly efficient new MHD code, ELITE, is used to calculate quantitative stability constraints on the pedestal, including con straits on the pedestal height. Because of the impact of collisionality on the bootstrap current, these pedestal constraints are dependant on the density and temperature separately, rather than simply on the pressure. A model of various ELM types is developed, and quantitatively compared to data. A number of observations agree with predictions, including ELM onset times, ELM depth and variation in pedestal height with collisionality and discharge shape. Stability analysis of series of model equilibria are used both o predict and interpret pedestal trends in existing experiments and to project pedestal constraints for future burning plasma tokamak designs. (author)

  10. Volcanic features of Io

    International Nuclear Information System (INIS)

    Carr, M.H.; Masursky, H.; Strom, R.G.; Terrile, R.J.

    1979-01-01

    The volcanic features of Io as detected during the Voyager mission are discussed. The volcanic activity is apparently higher than on any other body in the Solar System. Its volcanic landforms are compared with features on Earth to indicate the type of volcanism present on Io. (U.K.)

  11. Kinnisvarafirmade TOP 90

    Index Scriptorium Estoniae

    2002-01-01

    TOP 90. Kinnisvara valdkondade TOP 5. Käibe TOP 30. Käibe kasvu TOP 30. Rentaabluse TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Varade tootlikkuse TOP 30. Kinnisvarafirmade üldandmed. Kinnisvarafirmade finantsandmed

  12. Influence of the plasma pedestal parameters on ELM mitigation at low collisionality

    Energy Technology Data Exchange (ETDEWEB)

    Leuthold, Nils [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Universitaet Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth (Germany); Suttrop, Wolfgang [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

    2016-07-01

    The control of Edge Localized Modes (ELMs) is of great importance for future fusion devices in order to provide longevity of the plasma facing components and a better overall plasma performance. In recent magnetic perturbation ELM mitigation experiments in ASDEX Upgrade at low pedestal collisionality, the dependence of ELM losses on pedestal parameters is investigated. It is found that the reduction of the stored energy loss associated with ELMs occurs in correlation with a reduction of edge density and edge pedestal pressure induced by the applied magnetic perturbation (''pedestal pump-out''). Significant ELM mitigation occurs at lowest densities, in a region of pedestal n-T parameter space that has not been accessible in ASDEX Upgrade without magnetic perturbations, and which is occupied by type-IV ELMs in DIII-D. The role of magnetic perturbations for ELM mitigation will be discussed in this context and attempts to counteract the confinement loss by increasing neutral beam injection power or pellet injection increases the ELM energy losses.

  13. Theory and theory-based models for the pedestal, edge stability and ELMs in tokamaks

    International Nuclear Information System (INIS)

    Guzdar, P.N.; Mahajan, S.M.; Yoshida, Z.; Dorland, W.; Rogers, B.N.; Bateman, G.; Kritz, A.H.; Pankin, A.; Voitsekhovitch, I.; Onjun, T.; Snyder, S.

    2005-01-01

    Theories for equilibrium and stability of H-modes, and models for use within integrated modeling codes with the objective of predicting the height, width and shape of the pedestal at the edge of H-mode plasmas in tokamaks, as well as the onset and frequency of Edge Localized Modes (ELMs), are developed. A theory model for relaxed plasma states with flow, which uses two-fluid Hall-MHD equations, predicts that the natural scale length of the pedestal is the ion skin depth and the pedestal width is larger than the ion poloidal gyro-radius, in agreement with experimental observations. Computations with the GS2 code are used to identify micro-instabilities, such as electron drift waves, that survive the strong flow shear, diamagnetic flows, and magnetic shear that are characteristic of the pedestal. Other instabilities on the pedestal and gyro-radius scale, such as the Kelvin-Helmholtz instability, are also investigated. Time-dependent integrated modeling simulations are used to follow the transition from L-mode to H-mode and the subsequent evolution of ELMs as the heating power is increased. The flow shear stabilization that produces the transport barrier at the edge of the plasma reduces different modes of anomalous transport and, consequently, different channels of transport at different rates. ELM crashes are triggered in the model by pressure-driven ballooning modes or by current-driven peeling modes. (author)

  14. ELMs and constraints on the H-mode pedestal: A model based on peeling-ballooning modes

    International Nuclear Information System (INIS)

    Snyder, P.B.

    2002-01-01

    Maximizing the pedestal height while maintaining acceptable ELMs is a key issue for optimizing tokamak performance. We present a model for ELMs and pedestal constraints based upon theoretical analysis of edge instabilities which can limit the pedestal height and drive ELMs. Sharp pedestal pressure gradients drive large bootstrap currents which play a complex dual role in the stability physics. Consequently, the dominant modes are often intermediate-n coupled 'peeling-ballooning' modes, driven both by current and the pressure gradient. A highly efficient new MHD code, ELITE, is used to study these modes, and calculate quantitative stability constraints on the pedestal, including direct constraints on the pedestal height. A model of various ELM types is developed, and quantitatively compared to data from several tokamaks. A number of observations agree with predictions, including ELM onset times, ELM depth, and variation in pedestal height with discharge shape. Projections of pedestal stability constraints for Next Step designs, and nonlinear simulations of peeling-ballooning modes using the BOUT code are also presented. (author)

  15. A two term model of the confinement in Elmy H-modes using the global confinement and pedestal databases

    International Nuclear Information System (INIS)

    2003-01-01

    Two different physical models of the H-mode pedestal are tested against the joint pedestal-core database. These models are then combined with models for the core and shown to give a good fit to the ELMy H-mode database. Predictions are made for the next step tokamaks ITER and FIRE. (author)

  16. ELMs and constraints on the H-mode pedestal: peeling-ballooning stability calculation and comparison with experiment

    International Nuclear Information System (INIS)

    Snyder, P.B.; Ferron, J.R.; Wilson, H.R.

    2004-01-01

    We review and test the peeling-ballooning model for edge localized modes (ELMs) and pedestal constraints, a model based upon theoretical analysis of magnetohydrodynamic (MHD) instabilities that can limit the pedestal height and drive ELMs. A highly efficient MHD stability code, ELITE, is used to calculate quantitative stability constraints on the pedestal, including constraints on the pedestal height. Because of the impact of collisionality on the bootstrap current, these pedestal constraints are dependent on the density and temperature separately, rather than simply on the pressure. ELITE stability calculations are directly compared with experimental data for a series of plasmas in which the density is varied and ELM characteristics change. In addition, a technique is developed whereby peeling-ballooning pedestal constraints are calculated as a function of key equilibrium parameters via ELITE calculations using series of model equilibria. This technique is used to successfully compare the expected pedestal height as a function of density, triangularity and plasma current with experimental data. Furthermore, the technique can be applied for parameter ranges beyond the purview of present experiments, and we present a brief projection of peeling-ballooning pedestal constraints for burning plasma tokamak designs. (author)

  17. The Volcanism Ontology (VO): a model of the volcanic system

    Science.gov (United States)

    Myer, J.; Babaie, H. A.

    2017-12-01

    We have modeled a part of the complex material and process entities and properties of the volcanic system in the Volcanism Ontology (VO) applying several top-level ontologies such as Basic Formal Ontology (BFO), SWEET, and Ontology of Physics for Biology (OPB) within a single framework. The continuant concepts in BFO describe features with instances that persist as wholes through time and have qualities (attributes) that may change (e.g., state, composition, and location). In VO, the continuants include lava, volcanic rock, and volcano. The occurrent concepts in BFO include processes, their temporal boundaries, and the spatio-temporal regions within which they occur. In VO, these include eruption (process), the onset of pyroclastic flow (temporal boundary), and the space and time span of the crystallization of lava in a lava tube (spatio-temporal region). These processes can be of physical (e.g., debris flow, crystallization, injection), atmospheric (e.g., vapor emission, ash particles blocking solar radiation), hydrological (e.g., diffusion of water vapor, hot spring), thermal (e.g., cooling of lava) and other types. The properties (predicates) relate continuants to other continuants, occurrents to continuants, and occurrents to occurrents. The ontology also models other concepts such as laboratory and field procedures by volcanologists, sampling by sensors, and the type of instruments applied in monitoring volcanic activity. When deployed on the web, VO will be used to explicitly and formally annotate data and information collected by volcanologists based on domain knowledge. This will enable the integration of global volcanic data and improve the interoperability of software that deal with such data.

  18. Using LGI experiments to achieve better understanding of pedestal-edge coupling in NSTX-U

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhehui [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

    PowerPoint presentation. Latest advances in granule or dust injection technologies, fast and high-resolution imaging, together with micro-/nano-structured material fabrication, provide new opportunities to examine plasma-material interaction (PMI) in magnetic fusion environment. Some of our previous work in these areas is summarized. The upcoming LGI experiments in NSTX-U will shed new light on granular matter transport in the pedestal-edge region. In addition to particle control, these results can also be used for code validation and achieving better understanding of pedestal-edge coupling in fusion plasmas in both NSTX-U and others.

  19. Kinnisvarafirmade TOP 90

    Index Scriptorium Estoniae

    2003-01-01

    Kinnisvarafirmade TOP 90. Rentaabluse TOP 30. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Varade tootlikkuse TOP 30. Kinnisvarafirmade üldandmed. Kinnisvarafirmade finantsandmed

  20. Teedeehitusfirmade TOP 24

    Index Scriptorium Estoniae

    2006-01-01

    Teedeehitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi Kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Teedeehitusfirmade üld- ja finantsandmed

  1. Koolitusfirmade TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Koolitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Koolitusfirmade üld- ja finantsandmed

  2. Telekommunikatsiooni TOP aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Telekommunikatsiooni TOP aastal 2003. Käibe TOP 10. Käibe kasvu TOP 10. Rentaabluse TOP 10. Kasumi TOP 10. Kasumi kasvu TOP 10. Omakapitali tootlikkuse TOP 10. Telekommunikatsioonifirmade üldandmed. Telekommunikatsioonifirmade finantsandmed

  3. Põllumajandustootjate TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Põllumajandustootjate TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Põllumajandustootjate üld- ja finantsandmed

  4. Ehitusmaterjalitootjate TOP 95

    Index Scriptorium Estoniae

    2006-01-01

    Ehitusmaterjalitootjate TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Ehitusmaterjalitootjate üld- ja finantsandmed

  5. Development of new pedestal temperature models with self-consistent magnetic shear and safety factor in BALDUR and JETTO codes

    International Nuclear Information System (INIS)

    Suwanna, S.; Onjun, T.; Wongpan, P.; Parail, V.; Poolyarat, N.; Picha, R.

    2009-01-01

    Full text: A formation of a steep pressure gradient region near the plasma edge, called the pedestal, is a main reason for an improved performance in H-mode plasma. In this work, new pedestal temperature models are developed based on different theoretical-based width concepts: flow shear stabilization width concept, magnetic and flow shear stabilization width concept, and diamagnetic stabilization width concept. In the BALDUR code, each pedestal width model is combined with a ballooning mode pressure gradient model to predict the pedestal temperature, which is a boundary condition needed to predict plasma profiles. In the JETTO code, an anomalous transport is suppressed within the pedestal region, which results in a formation of a steep pressure gradient region. The pedestal width is predicted using these theoretically based width concepts. The plasma profiles in the pedestal region are limited by ELM crashes, which can be triggered either by ballooning modes or by peeling modes, depending on which instability is destabilized first. It is found in the BALDUR simulations that the simulated pedestal temperature profiles agree well with experimental data in the region close to the pedestal, but show larger deviation in the core region. In a preliminary investigation, these models agree reasonably well with experiments, yielding overall RMS less than 20%. Furthermore, the model based flow shear stabilization matches very well data from both DIII-D and JET, while the model based on magnetic and flow shear stabilization over-predicts results from JET and under-predicts those from DIII-D. Other statistical analyses such a calculation of offset values, ratios of predicted pedestal (resp. core) temperatures to those from experiments are performed. (author)

  6. A Volcanic Hydrogen Habitable Zone

    International Nuclear Information System (INIS)

    Ramirez, Ramses M.; Kaltenegger, Lisa

    2017-01-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N_2–CO_2–H_2O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO_2 outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H_2 can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N_2–CO_2–H_2O–H_2) can be sustained as long as volcanic H_2 output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H_2 warming is reduced in dense H_2O atmospheres. The atmospheric scale heights of such volcanic H_2 atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  7. A Volcanic Hydrogen Habitable Zone

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Ramses M.; Kaltenegger, Lisa, E-mail: rmr277@cornell.edu [Carl Sagan Institute, Cornell University, Ithaca, NY (United States)

    2017-03-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N{sub 2}–CO{sub 2}–H{sub 2}O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO{sub 2} outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H{sub 2} can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N{sub 2}–CO{sub 2}–H{sub 2}O–H{sub 2}) can be sustained as long as volcanic H{sub 2} output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H{sub 2} warming is reduced in dense H{sub 2}O atmospheres. The atmospheric scale heights of such volcanic H{sub 2} atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  8. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.; Delworth, Thomas L.; Ramaswamy, V.; Stouffer, Ronald J.; Wittenberg, Andrew; Zeng, Fanrong

    2009-01-01

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean

  9. Global and pedestal confinement in JET with a Be/W metallic wall

    Czech Academy of Sciences Publication Activity Database

    Beurskens, M.N.A.; Frassinetti, L.; Challis, C.; Giroud, C.; Saarelma, S.; Alper, B.; Angioni, C.; Bílková, Petra; Bourdelle, C.; Brezinsek, S.; Buratti, P.; Calabrò, G.; Eich, E.; Flanagan, J.; Giovannozzi, E.; Groth, M.; Hobirk, J.; Joffrin, E.; Leyland, M.J.; Lomas, P.; De La Luna, E.; Kempenaars, M.; Maddison, G.; Maggi, C.; Mantica, P.; Maslov, M.; Matthews, G.; Mayoral, M.-L.; Neu, R.; Nunes, I.; Osborne, T.; Rimini, F.; Scannell, R.; Solano, E.R.; Snyder, P.B.; Voitsekhovitch, I.; de Vries, P.

    2014-01-01

    Roč. 54, č. 4 (2014), 043001-043001 ISSN 0029-5515 Institutional support: RVO:61389021 Keywords : pedestal * confinement * nitrogen * radiation * tokamak * metal wall Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.062, year: 2014 http://iopscience.iop.org/0029-5515/54/4/043001/pdf/0029-5515_54_4_043001.pdf

  10. The effect of plasma collisionality on pedestal current density formation in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, D M; Leonard, A W; Osborne, T H; Groebner, R J; West, W P; Burrell, K H [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)

    2006-05-15

    The evolution and performance limits for the pedestal in H-mode are dependent on the two main drive terms for instability: namely the edge pressure gradient and the edge current density. These terms are naturally coupled though neoclassical (Pfirsch-Schluter and bootstrap) effects. On DIII-D, local measurements of the edge current density are made using an injected lithium beam in conjunction with Zeeman polarimetry and compared with pressure profile measurements made with other diagnostics. These measurements have confirmed the close spatial and temporal correlation that exists between the measured current density and the edge pressure in H- and QH-mode pedestals, where substantial pressure gradients exist. In the present work we examine the changes in the measured edge current for DIII-D pedestals which have a range of values for the ion and electron collisionalities {l_brace}{upsilon}{sub i}*,{upsilon}{sub e}*{r_brace} due to fuelling effects. Such changes in the collisionality in the edge are expected to significantly alter the level of the bootstrap current from the value predicted from the collisionless limit and therefore should correspondingly alter the pedestal stability limits. We find a clear decrease in measured current as {nu} increases, even for discharges having similar edge pressure gradients.

  11. Edge pedestal characteristics in JET and JT-60U tokamaks under variable toroidal field ripple

    NARCIS (Netherlands)

    Urano, H.; Saibene, G.; Oyama, N.; Parail, V.; P. de Vries,; Sartori, R.; Kamada, Y.; Kamiya, K.; Loarte, A.; Lonnroth, J.; Sakamoto, Y.; Salmi, A.; Shinohara, K.; Takenaga, H.; Yoshida, M.

    2011-01-01

    The effects of toroidal field (TF) ripple on the edge pedestal characteristics were examined in the TF ripple scan experiments at the plasma current I(p) of 1.1 MA in JET and JT-60U. The TF ripple amplitude delta(R) was defined as a value averaged over the existing ripple wells at the separatrix on

  12. Power exhaust by SOL and pedestal radiation at ASDEX Upgrade and JET

    Directory of Open Access Journals (Sweden)

    M. Bernert

    2017-08-01

    Applying these seed impurities for highly radiative scenarios impacts local plasma parameters and alters the impurity transport in the pedestal region. Thus, plasma confinement and stability can be affected. A proper understanding of the effects by these impurities is required in order to predict the applicability of such scenarios for future devices.

  13. Advances in measurement and modeling of the high-confinement-mode pedestal on the Alcator C-Mod tokamak

    International Nuclear Information System (INIS)

    Hughes, J.W.; LaBombard, B.; Mossessian, D.A.; Hubbard, A.E.; Terry, J.; Biewer, T.

    2006-01-01

    Edge transport barrier (ETB) studies on the Alcator C-Mod tokamak [Phys. Plasmas 1, 1511 (1994)] investigate pedestal scalings and the radial transport of plasma and neutrals. Pedestal profiles show trends with plasma operational parameters such as total current I P . A ballooning-like I P 2 dependence is seen in the pressure gradient, despite calculated stability to ideal ballooning modes. A similar scaling is seen in the near scrape-off layer for both low-confinement (L-mode) and H-mode discharges, possibly due to electromagnetic fluid drift turbulence setting transport near the separatrix. Neutral density diagnosis allows an examination of D 0 fueling in H-modes, yielding profiles of effective particle diffusivity in the ETB, which vary as I P is changed. Edge neutral transport is studied using a one-dimensional kinetic treatment. In both experiment and modeling, the C-Mod density pedestal exhibits a weakly increasing pedestal density and a nearly invariant density pedestal width as the D 0 source rate increases. Identical modeling performed on pedestal profiles typical of DIII-D [Nucl. Fusion 42, 614 (2002)] reveal differences in pedestal scalings qualitatively similar to experimental results

  14. Pedestal bifurcation and resonant field penetration at the threshold of edge-localized mode suppression in the DIII-D Tokamak.

    Science.gov (United States)

    Nazikian, R; Paz-Soldan, C; Callen, J D; deGrassie, J S; Eldon, D; Evans, T E; Ferraro, N M; Grierson, B A; Groebner, R J; Haskey, S R; Hegna, C C; King, J D; Logan, N C; McKee, G R; Moyer, R A; Okabayashi, M; Orlov, D M; Osborne, T H; Park, J-K; Rhodes, T L; Shafer, M W; Snyder, P B; Solomon, W M; Strait, E J; Wade, M R

    2015-03-13

    Rapid bifurcations in the plasma response to slowly varying n=2 magnetic fields are observed as the plasma transitions into and out of edge-localized mode (ELM) suppression. The rapid transition to ELM suppression is characterized by an increase in the toroidal rotation and a reduction in the electron pressure gradient at the top of the pedestal that reduces the perpendicular electron flow there to near zero. These events occur simultaneously with an increase in the inner-wall magnetic response. These observations are consistent with strong resonant field penetration of n=2 fields at the onset of ELM suppression, based on extended MHD simulations using measured plasma profiles. Spontaneous transitions into (and out of) ELM suppression with a static applied n=2 field indicate competing mechanisms of screening and penetration of resonant fields near threshold conditions. Magnetic measurements reveal evidence for the unlocking and rotation of tearinglike structures as the plasma transitions out of ELM suppression.

  15. Top Earners

    DEFF Research Database (Denmark)

    Badel, Alejandro; Daly, Moira; Huggett, Mark

    of the earnings distribution becomes thicker with age, and (3) the growth rate of earnings over the working lifetime is larger for groups with higher lifetime earnings. Models of top earners should account for these qualitative patterns and, importantly, for how they quantitatively differ across countries....

  16. Volcanic stratigraphy: A review

    Science.gov (United States)

    Martí, Joan; Groppelli, Gianluca; Brum da Silveira, Antonio

    2018-05-01

    Volcanic stratigraphy is a fundamental component of geological mapping in volcanic areas as it yields the basic criteria and essential data for identifying the spatial and temporal relationships between volcanic products and intra/inter-eruptive processes (earth-surface, tectonic and climatic), which in turn provides greater understanding of the geological evolution of a region. Establishing precise stratigraphic relationships in volcanic successions is not only essential for understanding the past behaviour of volcanoes and for predicting how they might behave in the future, but is also critical for establishing guidelines for exploring economic and energy resources associated with volcanic systems or for reconstructing the evolution of sedimentary basins in which volcanism has played a significant role. Like classical stratigraphy, volcanic stratigraphy should also be defined using a systematic methodology that can provide an organised and comprehensive description of the temporal and spatial evolution of volcanic terrain. This review explores different methods employed in studies of volcanic stratigraphy, examines four case studies that use differing stratigraphic approaches, and recommends methods for using systematic volcanic stratigraphy based on the application of the concepts of traditional stratigraphy but adapted to the needs of volcanological environment.

  17. Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall

    Science.gov (United States)

    Bowman, C.; Dickinson, D.; Horvath, L.; Lunniss, A. E.; Wilson, H. R.; Cziegler, I.; Frassinetti, L.; Gibson, K.; Kirk, A.; Lipschultz, B.; Maggi, C. F.; Roach, C. M.; Saarelma, S.; Snyder, P. B.; Thornton, A.; Wynn, A.; Contributors, JET

    2018-01-01

    The pressure gradient of the high confinement pedestal region at the edge of tokamak plasmas rapidly collapses during plasma eruptions called edge localised modes (ELMs), and then re-builds over a longer time scale before the next ELM. The physics that controls the evolution of the JET pedestal between ELMs is analysed for 1.4 MA, 1.7 T, low triangularity, δ  =  0.2, discharges with the ITER-like wall, finding that the pressure gradient typically tracks the ideal magneto-hydrodynamic ballooning limit, consistent with a role for the kinetic ballooning mode. Furthermore, the pedestal width is often influenced by the region of plasma that has second stability access to the ballooning mode, which can explain its sometimes complex evolution between ELMs. A local gyrokinetic analysis of a second stable flux surface reveals stability to kinetic ballooning modes; global effects are expected to provide a destabilising mechanism and need to be retained in such second stable situations. As well as an electron-scale electron temperature gradient mode, ion scale instabilities associated with this flux surface include an electro-magnetic trapped electron branch and two electrostatic branches propagating in the ion direction, one with high radial wavenumber. In these second stability situations, the ELM is triggered by a peeling-ballooning mode; otherwise the pedestal is somewhat below the peeling-ballooning mode marginal stability boundary at ELM onset. In this latter situation, there is evidence that higher frequency ELMs are paced by an oscillation in the plasma, causing a crash in the pedestal before the peeling-ballooning boundary is reached. A model is proposed in which the oscillation is associated with hot plasma filaments that are pushed out towards the plasma edge by a ballooning mode, draining their free energy into the cooler plasma there, and then relaxing back to repeat the process. The results suggest that avoiding the oscillation and maximising the region

  18. Autotranspordifirmade TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika 29. nov. lk. 10-11. Autofirmade TOP 100. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Majandustegevuse kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Autotranspordifirmade üld- ja finantsandmed. Delovõje Vedomosti : Transport i Logistika sisaldab tabelit Autofirmade TOP 100

  19. Characterization and parametric dependencies of low wavenumber pedestal turbulence in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D. R.; Fonck, R. J.; McKee, G. R.; Thompson, D. S. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Bell, R. E.; Diallo, A.; Guttenfelder, W.; Kaye, S. M.; LeBlanc, B. P.; Podesta, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2013-05-15

    The spherical torus edge region is among the most challenging regimes for plasma turbulence simulations. Here, we measure the spatial and temporal properties of ion-scale turbulence in the steep gradient region of H-mode pedestals during edge localized mode-free, MHD quiescent periods in the National Spherical Torus Experiment. Poloidal correlation lengths are about 10 ρ{sub i}, and decorrelation times are about 5 a/c{sub s}. Next, we introduce a model aggregation technique to identify parametric dependencies among turbulence quantities and transport-relevant plasma parameters. The parametric dependencies show the most agreement with transport driven by trapped-electron mode, kinetic ballooning mode, and microtearing mode turbulence, and the least agreement with ion temperature gradient turbulence. In addition, the parametric dependencies are consistent with turbulence regulation by flow shear and the empirical relationship between wider pedestals and larger turbulent structures.

  20. Edge stability and pedestal profile sensitivity of snowflake diverted equilibria in the TCV Tokamak

    International Nuclear Information System (INIS)

    Medvedev, S.Yu.; Ivanov, A.A.; Martynov, A.A.; Poshekhonov, Yu.Yu.; Behn, R.; Martin, Y.R.; Moret, J.M.; Piras, F.; Pitzschke, A.; Pochelon, A.; Sauter, O.; Villard, L.

    2010-01-01

    A second order null divertor (snowflake) has been successfully created and controlled in the TCV tokamak[1] (F. Piras et al., Plasma Phys. Control. Fusion, 2009). The results of ideal MHD edge stability computations show an enhancement of the edge stability properties of the snowflake equilibria compared to standard x-point configurations[2] (S. Yu. Medvedev et al., 36th EPS Conference on Plasma Physics, 2009). However, a sensitivity study of the stability limits to variations of the pedestal profiles is essential for making conclusions about possibilities of ELM control in snowflake plasmas. Variations of the edge stability and beta limits for several types of snowflake equilibria, different values of triangularity and various pedestal profiles are investigated (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Automatic diameter control system applied to the laser heated pedestal growth technique

    Directory of Open Access Journals (Sweden)

    Andreeta M.R.B.

    2003-01-01

    Full Text Available We described an automatic diameter control system (ADC, for the laser heated pedestal growth technique, that reduces the diameter fluctuations in oxide fibers grown from unreacted and non-sinterized pedestals, to less than 2% of the average fiber diameter, and diminishes the average diameter fluctuation, over the entire length of the fiber, to less than 1%. The ADC apparatus is based on an artificial vision system that controls the pulling speed and the height of the molten zone within a precision of 30 mum. We also show that this system can be used for periodic in situ axial doping the fiber. Pure and Cr3+ doped LaAlO3 and pure LiNbO3 were usedas model materials.

  2. High-Precision Dispensing of Nanoliter Biofluids on Glass Pedestal Arrays for Ultrasensitive Biomolecule Detection.

    Science.gov (United States)

    Chen, Xiaoxiao; Liu, Yang; Xu, QianFeng; Zhu, Jing; Poget, Sébastien F; Lyons, Alan M

    2016-05-04

    Precise dispensing of nanoliter droplets is necessary for the development of sensitive and accurate assays, especially when the availability of the source solution is limited. Conventional approaches are limited by imprecise positioning, large shear forces, surface tension effects, and high costs. To address the need for precise and economical dispensing of nanoliter volumes, we developed a new approach where the dispensed volume is dependent on the size and shape of defined surface features, thus freeing the dispensing process from pumps and fine-gauge needles requiring accurate positioning. The surface we fabricated, called a nanoliter droplet virtual well microplate (nVWP), achieves high-precision dispensing (better than ±0.5 nL or ±1.6% at 32 nL) of 20-40 nL droplets using a small source drop (3-10 μL) on isolated hydrophilic glass pedestals (500 μm on a side) bonded to arrays of polydimethylsiloxane conical posts. The sharp 90° edge of the glass pedestal pins the solid-liquid-vapor triple contact line (TCL), averting the wetting of the glass sidewalls while the fluid is prevented from receding from the edge. This edge creates a sufficiently large energy barrier such that microliter water droplets can be poised on the glass pedestals, exhibiting contact angles greater >150°. This approach relieves the stringent mechanical alignment tolerances required for conventional dispensing techniques, shifting the control of dispensed volume to the area circumscribed by the glass edge. The effects of glass surface chemistry and dispense velocity on droplet volume were studied using optical microscopy and high-speed video. Functionalization of the glass pedestal surface enabled the selective adsorption of specific peptides and proteins from synthetic and natural biomolecule mixtures, such as venom. We further demonstrate how the nVWP dispensing platform can be used for a variety of assays, including sensitive detection of proteins and peptides by fluorescence

  3. Experimental and computational evaluation of neutrals in the Alcator C-Mod edge pedestal

    Science.gov (United States)

    Hughes, J. W.; Mossessian, D.; Labombard, B.; Terry, J.

    2004-11-01

    Pedestal-forming edge transport barriers (ETBs) in tokamak plasmas and the physics governing them are linked to the enhancement of confinement obtained in H-mode plasmas. Studies on Alcator C-Mod employ experimental measurements and simple 1-D transport models in order to better understand ETB physics. We examine the influences of ionization and charge exchange on the pedestals in electron density and temperature. Routine measurements from edge Thomson scattering (ETS) give pedestal scalings with global plasma parameters, while individual ETS profiles are combined with scanning Langmuir probe data and optical D_α emissivity measurements to give atomic density profiles and the associated radial distribution of the ionization source rate. From H-mode profiles of these quantities a well in effective plasma diffusivity is calculated, and is shown to systematically vary as the confinement regime is varied from ELM-free to EDA. Experimental work is supplemented with modeling and computation of edge neutral transport via KN1D, a kinetic solver for atomic and molecular distribution functions in slab geometry. The level of agreement between experiment and model is encouraging.

  4. Volcanic Supersites as cross-disciplinary laboratories

    Science.gov (United States)

    Provenzale, Antonello; Beierkuhnlein, Carl; Giamberini, Mariasilvia; Pennisi, Maddalena; Puglisi, Giuseppe

    2017-04-01

    surface between the top of the vegetation and the rock matrix in active volcanic areas and Volcanic Supersites.

  5. Volcanism on Io

    Science.gov (United States)

    Davies, Ashley Gerard

    2014-03-01

    Preface; Introduction; Part I. Io, 1610 to 1995: Galileo to Galileo: 1. Io, 1610-1979; 2. Between Voyager and Galileo: 1979-95; 3. Galileo at Io; Part II. Planetary Volcanism: Evolution and Composition: 4. Io and Earth: formation, evolution, and interior structure; 5. Magmas and volatiles; Part III. Observing and Modeling Volcanic Activity: 6. Observations: thermal remote sensing of volcanic activity; 7. Models of effusive eruption processes; 8. Thermal evolution of volcanic eruptions; Part IV. Galileo at Io: the Volcanic Bestiary: 9. The view from Galileo; 10. The lava lake at Pele; 11. Pillan and Tvashtar: lava fountains and flows; 12. Prometheus and Amirani: Effusive activity and insulated flows; 13. Loki Patera: Io's powerhouse; 14. Other volcanoes and eruptions; Part V. Volcanism on Io: The Global View: 15. Geomorphology: paterae, shields, flows and mountains; 16. Volcanic plumes; 17. Hot spots; Part VI. Io after Galileo: 18. Volcanism on Io: a post-Galileo view; 19. The future of Io observations; Appendix 1; Appendix 2; References; Index.

  6. Autotranspordi TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    TOP 50. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Marika Roomere. Täisteenuse pakkumine kergitas tulemusi; Jupiter Plus otsib järjest uusi kasvuvõimalusi; EST-Trans Kaubaveod teenib kasumit toiduvedamisega

  7. Koolitusfirmade TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    Koolitusfirmade TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Signe Sillasoo. Invicta tahab lähiaastail laieneda Eestis ja mujalgi; Ketlin Priilinn. Addenda kasutas ära majanduse soodsa seisu. Kommenteerib Heli Sõmer. Juhtide hoiakute muutmisega tõus esikolmikusse

  8. Audiitorfirmade TOP aastal 2007

    Index Scriptorium Estoniae

    2008-01-01

    Audiitorfirmade TOP 51. Vt. samas: Urve Vilk. Audiitoriteni pole majanduslangus jõudnud; Intervjuu I.S. Audiitorteenuste OÜ omaniku Irina Somovaga; Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10

  9. Koolitusfirmade TOP aastal 2006

    Index Scriptorium Estoniae

    2007-01-01

    Koolitusfirmade TOP. Vt. samas: Käibe TOP10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Varade tootlikkuse TOP 10; Pille Rõivas. Võtmetegur meeskond; Vain & Partnerid: uudsus peitub sisus; Kristo Kiviorg. Teel Baltimaade koolitajate tippu

  10. Top reconstruction and boosted top experimental overview

    CERN Document Server

    Skinnari, Louise

    2015-01-01

    An overview of techniques used to reconstruct resolved and boosted top quarks is presented. Techniques for resolved top quark reconstruction include kinematic likelihood fitters and pseudo- top reconstruction. Many tools and methods are available for the reconstruction of boosted top quarks, such as jet grooming techniques, jet substructure variables, and dedicated top taggers. Different techniques as used by ATLAS and CMS analyses are described and the performance of different variables and top taggers are shown.

  11. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.

    2009-08-22

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  12. Helical variation of density profiles and fluctuations in the tokamak pedestal with applied 3D fields and implications for confinement

    Science.gov (United States)

    Wilcox, R. S.; Rhodes, T. L.; Shafer, M. W.; Sugiyama, L. E.; Ferraro, N. M.; Lyons, B. C.; McKee, G. R.; Paz-Soldan, C.; Wingen, A.; Zeng, L.

    2018-05-01

    Small 3D perturbations to the magnetic field in DIII-D ( δB /B ˜2 ×10-4 ) result in large modulations of density fluctuation amplitudes in the pedestal, which are shown using Doppler backscattering measurements to vary by a factor of 2. Helical perturbations of equilibrium density within flux surfaces have previously been observed in the pedestal of DIII-D plasmas when 3D fields are applied and were correlated with density fluctuation asymmetries in the pedestal. These intra-surface density and pressure variations are shown through two fluid MHD modeling studies using the M3D-C1 code to be due to the misalignment of the density and temperature equilibrium iso-surfaces in the pedestal region. This modeling demonstrates that the phase shift between the two iso-surfaces corresponds to the diamagnetic direction of the two species, with the mass density surfaces shifted in the ion diamagnetic direction relative to the temperature and magnetic flux iso-surfaces. The resulting pedestal density, potential, and turbulence asymmetries within flux surfaces near the separatrix may be at least partially responsible for several poorly understood phenomena that occur with the application of 3D fields in tokamaks, including density pump out and the increase in power required to transition from L- to H-mode.

  13. Initial results of H-mode edge pedestal turbulence evolution with quadrature reflectometer measurements on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G. [University of California, Los Angeles, CA 90095 (United States)]. E-mail: wangg@fusion.gat.com; Peebles, W.A. [University of California, Los Angeles, CA 90095 (United States); Doyle, E.J. [University of California, Los Angeles, CA 90095 (United States); Rhodes, T.L. [University of California, Los Angeles, CA 90095 (United States); Zeng, L. [University of California, Los Angeles, CA 90095 (United States); Nguyen, X. [University of California, Los Angeles, CA 90095 (United States); Osborne, T.H. [General Atomics, San Diego, CA 92186-5608 (United States); Snyder, P.B. [General Atomics, San Diego, CA 92186-5608 (United States); Kramer, G.J. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Nazikian, R. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Groebner, R.J. [General Atomics, San Diego, CA 92186-5608 (United States); Burrell, K.H. [General Atomics, San Diego, CA 92186-5608 (United States); Leonard, A.W. [General Atomics, San Diego, CA 92186-5608 (United States); Fenstermacher, M.E. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Strait, E.J. [General Atomics, San Diego, CA 92186-5608 (United States)

    2007-06-15

    High-resolution quadrature reflectometer measurements of density fluctuation levels have been obtained on DIII-D for H-mode edge pedestal studies. Initial results are presented from the L-H transition to the first ELM for two cases: (i) a low pedestal beta discharge, in which density turbulence in the pedestal has little change during the ELM-free phase, and (ii) a high pedestal beta discharge in which both density and magnetic turbulence are observed to increase before the first ELM. These high beta data are consistent with the existence of electromagnetic turbulence suggested by some transport models. During Type-I ELM cycles, when little magnetic turbulence can be observed, pedestal turbulence increases just after an ELM crash and then decreases before next ELM strikes, in contrast to a drop after ELM crash and then it re-grows when strong magnetic turbulence shows similar behavior. Clear ELM precursors are observed on {<=}20% of Type-I ELMs observed to date.

  14. H-mode pedestal characteristics, ELMs, and energy confinement in ITER shape discharges on DIII-D

    International Nuclear Information System (INIS)

    Osborne, T.H.; Groebner, R.J.; Lao, L.L.; Leonard, A.W.; Miller, R.L.; Thomas, D.M.; Waltz, R.E.; Maingi, R.; Porter, G.D.

    1997-12-01

    The H-mode confinement enhancement factor, H, is found to be strongly correlated with the height of the edge pressure pedestal in ITER shape discharges. In discharges with Type I ELMs the pedestal pressure is set by the maximum pressure gradient before the ELM and the width of the H-mode transport barrier. The pressure gradient before Type I ELMs is found to scale as would be expected for a stability limit set by ideal ballooning modes, but with values significantly in excess of that predicted by stability code calculations. The width of the H-mode transport barrier is found to scale equally well with pedestal P(POL)(2/3) or B(POL)(1/2). The improved H value in high B(POL) discharges may be due to a larger edge pressure gradient and wider H-mode transport barrier consistent with their higher edge ballooning mode limit. Deuterium puffing is found to reduce H consistent with the smaller pedestal pressure which results from the reduced barrier width and critical pressure gradient. Type I ELM energy loss is found to be proportional to the change in the pedestal energy

  15. L-H Power Threshold, Pedestal Stability and Confinement in JET with a Metallic Wall

    Energy Technology Data Exchange (ETDEWEB)

    Beurskens, M.; Alper, B.; Challis, C.; Flanagan, J.; Giroud, C.; Kempenaars, M.; Lomas, P.; Maslov, M.; Matthews, G.; Mayoral, M. L.; Snyder, P. B.; Saarelma, S., E-mail: marc.beurskens@ccfe.ac.uk [EURATOM /CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Frassinetti, L. [Division of Fusion Plasma Physics, Association EURATOM-VR , Stockholm (Sweden); Maggi, C.; Angioni, C.; Hobirk, J.; Neu, R. [IPP Garching, Garching (Germany); Calabro, G.; Buratti, P.; Giovannozzi, E. [Associazione EURATOM-ENEA sulla Fusione, Frascati (Italy); Bourdelle, C.; Joffrin, E. [Association Euratom-CEA, IRFM, St-Paul-Lez-Durance (France); Brezinsek, S. [Forschungszentrum Juelich, Juelich (Germany); Groth, M. [Association EURATOM/Helsinki University of Technology, Espoo (Finland); Leyland, M. [Department of Physics, University of York, Heslington, York (United Kingdom); De la Luna, E. [Ciemat, Madrid (Spain); Mantica, P. [Istituto di Fisica del Plasma ' P. Caldirola' , Milano (Italy); Nunes, I. [Centro de Fusao Nuclear, Associacao EURATOM-IST, Lisboa (Portugal); Osborne, T. [General Atomics, San Diego (United States); De Vries, P. [FOM DIFFER, Nieuwegein (Netherlands)

    2012-09-15

    Full text: After the change-over from the Carbon-Fibre Composite (CFC) wall to an ITER-like metallic wall (ILW) the baseline type I ELMy H-mode scenario has been re-established in JET with the new plasma-facing materials Be and W. A key finding for ITER is that the power required to enter H-mode has reduced with respect to that in JET with the CFC wall. In JET with the ILW the power threshold to enter H-mode (P{sub L-H}) is below the international L-H power threshold scaling P{sub Martin-08}. The minimum threshold is P{sub L-H} = 1.8 MW compared to P{sub Martin-08} = 4 MW with a pedestal density of n{sub ped} = 2 x 10{sup 19} m{sup -3} in plasmas with I{sub p} = 2.0 MA, B{sub t} = 2.4 T. However the threshold depends strongly on density; using slow ion cyclotron heating (ICRH) power ramps P{sub L-H} varies from 1.8 to 4.5 MW in a range of lower and upper plasma triangularity ({delta}{sub L} = 0.32 - 0.4, {delta}{sub U} = 0.19 - 0.38). Stationary Type I ELMy H-mode operation has been re-established at both low and high triangularity with I{sub p} {<=} 2.5 MA, q{sub 95} = 2.8 - 3.6 and H{sub 98} {<=} 1. The achieved plasma collisionality is relatively high, in the range of 1 < v{sub eff} < 4 due to the required strong gas dosing. Stability analysis with the linear MHD stability code ELITE show that the pedestal is marginally unstable with respect to the Peeling Ballooning boundary. Due to the stabilising effect of the global pressure on the pedestal stability, a strong coupling between core and edge confinement is expected. Indeed in an H-mode profile database comparison with 119 CFC- (0.1 < v{sub eff} < 1) and 40 ILW-H-modes a strong coupling of the core versus edge confinement is found, independent of wall material. In addition, the pedestal predictions using the EPED predictive pedestal code coincide with the measured pedestal height over a wide range of normalised pressure 1.5 < {beta}{sub N} < 3.5. Due to the strong core-edge coupling, beneficial effects of core

  16. Volcanic Rocks and Features

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. The...

  17. Volcanic Eruptions in Kamchatka

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Sheveluch Stratovolcano Click on the image for full resolution TIFF Klyuchevskoy Stratovolcano Click on the image for full resolution TIFF One of the most volcanically active regions of the world is the Kamchatka Peninsula in eastern Siberia, Russia. It is not uncommon for several volcanoes to be erupting at the same time. On April 26, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radioneter (ASTER) on NASA's Terra spacecraft captured these images of the Klyuchevskoy and Sheveluch stratovolcanoes, erupting simultaneously, and 80 kilometers (50 miles) apart. Over Klyuchevskoy, the thermal infrared data (overlaid in red) indicates that two open-channel lava flows are descending the northwest flank of the volcano. Also visible is an ash-and-water plume extending to the east. Sheveluch volcano is partially cloud-covered. The hot flows highlighted in red come from a lava dome at the summit. They are avalanches of material from the dome, and pyroclastic flows. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra spacecraft. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and

  18. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    International Nuclear Information System (INIS)

    Cuttitta, Christina M.; Ericson, Daniel L.; Scalia, Alexander; Roessler, Christian G.; Teplitsky, Ella; Joshi, Karan; Campos, Olven; Agarwal, Rakhi; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S.

    2015-01-01

    An acoustic high-throughput screening method is described for harvesting protein crystals and combining the protein crystals with chemicals such as a fragment library. Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s −1 ) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening

  19. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    Energy Technology Data Exchange (ETDEWEB)

    Cuttitta, Christina M. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); The City University of New York, 2800 Victory Boulevard, Staten Island, NY 10314 (United States); Ericson, Daniel L. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); University at Buffalo, SUNY, 12 Capen Hall, Buffalo, NY 14260 (United States); Scalia, Alexander [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Binghamton University, 4400 Vestal Parkway East, Binghamton, NY 11973-5000 (United States); Roessler, Christian G. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Teplitsky, Ella [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Stony Brook University, Stony Brook, NY 11794-5215 (United States); Joshi, Karan [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); PEC University of Technology, Chandigarh (India); Campos, Olven [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33414 (United States); Agarwal, Rakhi; Allaire, Marc [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Orville, Allen M. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Sweet, Robert M.; Soares, Alexei S., E-mail: soares@bnl.gov [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2015-01-01

    An acoustic high-throughput screening method is described for harvesting protein crystals and combining the protein crystals with chemicals such as a fragment library. Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s{sup −1}) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening.

  20. H-Mode Turbulence, Power Threshold, ELM, and Pedestal Studies in NSTX

    International Nuclear Information System (INIS)

    Maingi, R.; Bush, C.E.; Fredrickson, E.D.; Gates, D.A.; Kaye, S.M.; LeBlanc, B.P.; Menard, J.E.; Meyer, H.; Mueller, D.; Nishino, N.; Roquemore, A.L.; Sabbagh, S.A.; Tritz, K.; Zweben, S.J.; Bell, M.G.; Bell, R.E.; Biewer, T.; Boedo, J.A.; Johnson, D.W.; Kaita, R.; Kugel, H.W.; Maqueda, R.J.; Munsat, T.; Raman, R.; Soukhanovskii, V.A.; Stevenson, T.; Stutman, D.

    2004-01-01

    High-confinement mode (H-mode) operation plays a crucial role in NSTX [National Spherical Torus Experiment] research, allowing higher beta limits due to reduced plasma pressure peaking, and long-pulse operation due to high bootstrap current fraction. Here, new results are presented in the areas of edge localized modes (ELMs), H-mode pedestal physics, L-H turbulence, and power threshold studies. ELMs of several other types (as observed in conventional aspect ratio tokamaks) are often observed: (1) large, Type I ELMs, (2) ''medium'' Type II/III ELMs, and (3) giant ELMs which can reduce stored energy by up to 30% in certain conditions. In addition, many high-performance discharges in NSTX have tiny ELMs (newly termed Type V), which have some differences as compared with ELM types in the published literature. The H-mode pedestal typically contains between 25-33% of the total stored energy, and the NSTX pedestal energy agrees reasonably well with a recent international multi-machine scaling. We find that the L-H transition occurs on a ∼100 (micro)sec timescale as viewed by a gas puff imaging diagnostic, and that intermittent quiescent periods precede the final transition. A power threshold identity experiment between NSTX and MAST shows comparable loss power at the L-H transition in balanced double-null discharges. Both machines require more power for the L-H transition as the balance is shifted toward lower single null. High field side gas fueling enables more reliable H-mode access, but does not always lead to a lower power threshold e.g., with a reduction of the duration of early heating. Finally the edge plasma parameters just before the L-H transition were compared with theories of the transition. It was found that while some theories can separate well-developed L- and H-mode data, they have little predictive value

  1. Martian volcanism: A review

    International Nuclear Information System (INIS)

    Carr, M.H.

    1987-01-01

    Martian volcanism is reviewed. It is emphasized that lava plains constitute the major type of effusive flow, and can be differentiated by morphologic characteristics. Shield volcanoes, domes, and patera constitute the major constructional landforms, and recent work has suggested that explosive activity and resulting pyroclastic deposits may have been involved with formation of some of the small shields. Analysis of morphology, presumed composition, and spectroscopic data all indicate that Martian volcanism was dominantly basaltic in composition

  2. X transport and its effect on H-mode and edge pedestal in tokamaks

    International Nuclear Information System (INIS)

    Chang, C.S.; Darrow, D.; White, R.; Lin, Z.; Lee, W.; Ku, S.H.; Weitzner, H.; Carlstrom, T.N.; Grassie, J.S. de

    2001-01-01

    A new classical non-ambipolar transport mechanism has been identified which can be a dominant source of strong Er and edge pedestal layer formation immediately inside the separatrix in a diverted tokamak. Due to vanishingly small poloidal B-field and grad-B drift toward x-point, plasma ions with small ν parallel in the X-region do not have confined single particle orbits. This leads to a non-ambipolar convective transport in the X-region (X-transport), either collisional or collisionless, inducing a strong negative Er-shear layer. The X-transport can provide basic understanding of many of the experimental observations. (author)

  3. Radially global δf computation of neoclassical phenomena in a tokamak pedestal

    International Nuclear Information System (INIS)

    Landreman, Matt; Parra, Felix I; Catto, Peter J; Ernst, Darin R; Pusztai, Istvan

    2014-01-01

    Conventional radially-local neoclassical calculations become inadequate if the radial gradient scale lengths of the H-mode pedestal become as small as the poloidal ion gyroradius. Here, we describe a radially global δf continuum code that generalizes neoclassical calculations to allow for stronger gradients. As with conventional neoclassical calculations, the formulation is time-independent and requires only the solution of a single sparse linear system. We demonstrate precise agreement with an asymptotic analytic solution of the radially global kinetic equation in the appropriate limits of aspect ratio and collisionality. This agreement depends crucially on accurate treatment of finite orbit width effects. (paper)

  4. The L-H transition and the stability of the edge pedestal

    International Nuclear Information System (INIS)

    Rogers, B.N.; Drake, J.F.; Zeiler, A.

    2001-01-01

    Based on three-dimensional simulations of the Braginskii equations, we identify two main parameters which control transport in the edge of tokamaks: the MHD ballooning parameter and a diamagnetic parameter. The space defined by these parameters delineates regions where typical L-mode levels of transport arise, where the transport is catastrophically large (density limit) and where the plasma spontaneously forms a transport barrier (H-mode). Ion diamagnetic effects allow the edge pedestal to steepen well beyond the first ideal MHD stability boundary. (author)

  5. The role of the density profile in the ASDEX-Upgrade pedestal structure

    Czech Academy of Sciences Publication Activity Database

    Dunne, M.G.; Potzel, S.; Reimold, F.; Wischmeier, M.; Wolfrum, E.; Frassinetti, L.; Beurskens, M.; Bílková, Petra; Cavedon, M.; Fischer, R.; Kurzan, B.; Laggner, F.M.; McDermott, R.M.; Tardini, G.; Trier, E.; Viezzer, E.; Willensdorfer, M.

    2017-01-01

    Roč. 59, č. 1 (2017), č. článku 014017. ISSN 0741-3335. [EPS 2016: Conference on Plasma Physics/43./. Leuven, 04.07.2016-08.07.2016] EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : pedestal * scrape-off layer * peeling-balooning * prediction Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.392, year: 2016 http://iopscience.iop.org/0741-3335/59/1/014017

  6. Kinetic neutral transport effects in the pedestal of H-mode discharges in the DIII-D tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Owen, L.W. [Oak Ridge National Laboratory, Building 5700, MS-6169, Oak Ridge, TN 37831-8072 (United States)]. E-mail: owenlw@ornl.gov; Groebner, R.J. [General Atomics, P.O. Box 85608, San Diego, CA 92186-9784 (United States); Mahdavi, M.A. [General Atomics, P.O. Box 85608, San Diego, CA 92186-9784 (United States)

    2005-03-01

    A series of hydrogen and deuterium discharges are analyzed with fluid plasma and Monte Carlo neutrals codes. Comparison of poloidally averaged radial distributions of core neutral density and ionization with analytic solutions of 1-D plasma and neutrals continuity equations support the hypothesis that the width of the density pedestal is largely determined by the neutral source. The increased neutral penetration depth that arises from multiple charge exchange can be included in the analytic model with radially dependent scale lengths. The scale length in the analytic model depends on the neutral fluid velocity which increases across the divertor and pedestal as the neutral atoms charge exchange with the higher temperature background ions. The neutral penetration depth and corresponding density pedestal width depend sensitively on the neutral temperature and the degree of ion-neutral temperature equilibration.

  7. The Influence of Slowly Varying Mass on Severity of Dynamics Nonlinearity of Bearing-Rotor Systems with Pedestal Looseness

    Directory of Open Access Journals (Sweden)

    Mian Jiang

    2018-01-01

    Full Text Available Nonlinearity measure is proposed to investigate the influence of slowly varying mass on severity of dynamics nonlinearity of bearing-rotor systems with pedestal looseness. A nonlinear mathematical model including the effect of slowly varying disk mass is developed for a bearing-rotor system with pedestal looseness. The varying of equivalent disk mass is described by a cosine function, and the amplitude coefficient is used as a control parameter. Then, nonlinearity measure is employed to quantify the severity of dynamics nonlinearity of bearing-rotor systems. With the increasing of looseness clearances, the curves that denote the trend of nonlinearity degree are plotted for each amplitude coefficient of mass varying. It can be concluded that larger amplitude coefficients of the disk mass varying will have more influence on the severity of dynamics nonlinearity and generation of chaotic behaviors in rotor systems with pedestal looseness.

  8. Dimensionless scalings of confinement, heat transport and pedestal stability in JET-ILW and comparison with JET-C

    Czech Academy of Sciences Publication Activity Database

    Frassinetti, L.; Saarelma, S.; Lomas, P.; Nunes, I.; Rimini, F.; Beurskens, M.N.A.; Bílková, Petra; Boom, J.E.; De La Luna, E.; Delabie, E.; Drewelow, P.; Flanagan, J.; Garzotti, L.; Giroud, C.; Hawks, N.; Joffrin, E.; Kempenaars, M.; Kim, H.-T.; Kruezi, U.; Loarte, A.; Lomanowski, B.; Lupelli, I.; Meneses, L.; Maggi, C.F.; Menmuir, S.; Peterka, Matěj; Rachlew, E.; Romanelli, M.; Stefanikova, E.

    2017-01-01

    Roč. 59, č. 1 (2017), č. článku 014014. ISSN 0741-3335. [EPS 2016: Conference on Plasma Physics/43./. Leuven, 04.07.2016-08.07.2016] EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : JET-ILW * dimensionless scaling * pedestal * confinement * pedestal stability * heat transport Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.392, year: 2016 http://dx.doi.org/10.1088/0741-3335/59/1/014014

  9. International workshop of the Confinement Database and Modelling Expert Group in collaboration with the Edge and Pedestal Physics Expert Group

    International Nuclear Information System (INIS)

    Cordey, J.; Kardaun, O.

    2001-01-01

    A Workshop of the Confinement Database and Modelling Expert Group (EG) was held on 2-6 April at the Plasma Physics Research Center of Lausanne (CRPP), Switzerland. Presentations were held on the present status of the plasma pedestal (temperature and energy) scalings from an empirical and theoretical perspective. An integrated approach to modelling tokamaks incorporating core transport, edge pedestal and SOL, together with a model for ELMs was presented by JCT. New experimental data on on global H-mode confinement were discussed and presentations on L-H threshold power were made

  10. Stratigraphical sequence and geochronology of the volcanic rock series in caifang basin, south jiangxi

    International Nuclear Information System (INIS)

    Xu Xunsheng; Wu Jianhua

    2010-01-01

    The late Mesozoic volcanic rocks in Jiangxi constitute two volcanic belts: the northern is Xiajiang-Guangfeng volcanic belt, the volcanic rocks series belong to one volcano cycle and named Wuyi group which is subdivided into three formations (Shuangfengling formation, Ehuling formation and Shixi formation); the southern is Sannan-Xunwu volcanic belt, the volcanic rocks series in Caifang basin which locates on Sannan-Xunwu volcanic belt also belong to only one volcano cycle. It can be subdivided into two lithology and lithofacies units (upper and lower): the lower unit consists of sedimentary rocks and associated with a subordinate amount of volcanic rocks, it belongs to erupt-deposit facies which is the product of early volcanic stage; the upper unit is mostly composed of volcanic rocks, it belongs to erupt facies that is the volcanic eruption product. SHRIMP zircon U-Pb age of rhyolite? which locates at the top of the upper unit is 130.79 ± 0.73) Ma. According to the new International Stratigraphic Chart, the boundary of Jurassic and Cretaceous is (145.4 ± 4.0) Ma, so the age shows that the geologic period of Caifang volcanic rocks series is early Early Cretaceous epoch. On the basis of lithological correlation, lithofacies and stratigraphic horizon analysis, the volcanic rock series in Caifang basin fall under Wuyi group, and the lower unit could be incorporated into Shuangfengling formation, the upper unit could be incorporated into Ehuling formation. The subdivision of sequence and the determination of geochronology of the volcanic rock series in Caifang basin provide some references for the study of the late Mesozoic volcanic rocks series of the Sannan-Xunwu volcanic belt. (authors)

  11. Dynamics of the pedestal structure in the edge transport barrier in CHS

    International Nuclear Information System (INIS)

    Kado, S.; Oishi, T.; Tanaka, S.

    2006-10-01

    The dynamic behavior of the edge pedestal in the edge transport barrier (ETB) formation discharge (H-mode) in the compact helical system (CHS) is investigated. Edge Harmonic Oscillations (EHOs) having a fundamental frequency of 2-4.5 kHz, depending on the magnetic configuration, and their second harmonic are observed when the density gradient of the pedestal reaches a certain threshold. There are two groups of so-called EHOs in the CHS. One is located in the edge region where the ι=1 surface exists, and the other is in the core region (although we also call it EHO in this paper) around the half radius where the ι=0.5 surface exists. The magnetic probe signal is revealed to reflect the latter mode, showing the poloidal mode number of 2, while that for the edge BES channel is 1. The density build-up saturates simultaneously with the increase of EHOs in the edge BES channel, which suggests that to a considerable extend the mode increases the particle transport. (author)

  12. Evolution of edge pedestal transport between edge-localized modes in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Floyd, J.-P.; Stacey, W. M.; Mellard, S. C. [Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Groebner, R. J. [General Atomics, San Diego, California 92186 (United States)

    2015-02-15

    Evolution of measured profiles of densities, temperatures, and velocities in the edge pedestal region between successive ELM (edge-localized mode) events are analyzed and interpreted in terms of the constraints imposed by particle, momentum and energy balance in order to gain insights regarding the underlying evolution of transport processes in the edge pedestal between ELMs in a series of DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] discharges. The data from successive inter-ELM periods during an otherwise steady-state phase of the discharges were combined into a composite inter-ELM period for the purpose of increasing the number of data points in the analysis. Variation of diffusive and non-diffusive (pinch) particle, momentum, and energy transport over the inter-ELM period are interpreted using the GTEDGE code for discharges with plasma currents from 0.5 to 1.5 MA and inter-ELM periods from 50 to 220 ms. Diffusive transport is dominant for ρ < 0.925, while non-diffusive and diffusive transport are very large and nearly balancing in the sharp gradient region 0.925 < ρ < 1.0. During the inter-ELM period, diffusive transport increases slightly more than non-diffusive transport, increasing total outward transport. Both diffusive and non-diffusive transport have a strong inverse correlation with plasma current.

  13. Arvutifirmade TOP 101 aastal 2004

    Index Scriptorium Estoniae

    2005-01-01

    Arvutifirmade TOP 101; Käibe TOP 20; Käibe kasvu TOP 15; Kasumi TOP 15; Rentaabluse TOP 20; Kasumi kasvu TOP 15; Omakapiali tootlikkuse TOP 15; Eesti arvutifirmade finantsandmed; Arvutifirmade üldandmed

  14. Jaekaubanduse TOP 100 aastal 2001

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Varade tootlikkuse TOP 30. Jaekaubandusettevõtete finantsseadmed. Jaekaubandusettevõtete üldandmed

  15. Jaekaubandusettevõtete TOP 70

    Index Scriptorium Estoniae

    2005-01-01

    Jaekaubandusettevõtete TOP 70; Käibe TOP 25; Kasumi TOP 25; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Jaekaubandusettevõtete üld- ja finantsandmed

  16. Majutusasutuste TOP 40 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Majutusasutuste TOP 40 aastal 2002. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Majutusasutuste üldandmed. Majutusasutuste finantsandmed

  17. Volcanic hazards to airports

    Science.gov (United States)

    Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.

    2009-01-01

    Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

  18. ROLE OF NEUTRALS IN CORE FUELING AND PEDESTAL STRUCTURE IN H-MODE DIII-D DISCHARGES

    International Nuclear Information System (INIS)

    WOLF, NS; PETRIE, TW; PORTER, GD; ROGNLIEN, TD; GROEBNER, RJ; MAKOWSKI, MA

    2002-01-01

    OAK A271 ROLE OF NEUTRALS IN CORE FUELING AND PEDESTAL STRUCTURE IN H-MODE DIII-D DISCHARGES. The 2-D fluid code UEDGE was used to analyze DIII-D experiments to determine the role of neutrals in core fueling, core impurities, and also the H-mode pedestal structure. The authors compared the effects of divertor closure on the fueling rate and impurity density of high-triangularity, H-mode plasmas. UEDGE simulations indicate that the decrease in both deuterium core fueling (∼ 15%-20%) and core carbon density (∼ 15%-30%) with the closed divertor compared to the open divertor configuration is due to greater divertor screening of neutrals. They also compared UEDGE results with a simple analytic model of the H-mode pedestal structure. The model predicts both the width and gradient of the transport barrier in n e as a function of the pedestal density. The more sophisticated UEDGE simulations of H-mode discharges corroborate the simple analytic model, which is consistent with the hypothesis that fueling processes play a role in H-mode transport barrier formation

  19. Modeling volcanic ash dispersal

    CERN Multimedia

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  20. Gyrokinetic neoclassical study of the bootstrap current in the tokamak edge pedestal with fully non-linear Coulomb collisions

    Energy Technology Data Exchange (ETDEWEB)

    Hager, Robert, E-mail: rhager@pppl.gov; Chang, C. S., E-mail: cschang@pppl.gov [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

    2016-04-15

    As a follow-up on the drift-kinetic study of the non-local bootstrap current in the steep edge pedestal of tokamak plasma by Koh et al. [Phys. Plasmas 19, 072505 (2012)], a gyrokinetic neoclassical study is performed with gyrokinetic ions and drift-kinetic electrons. Besides the gyrokinetic improvement of ion physics from the drift-kinetic treatment, a fully non-linear Fokker-Planck collision operator—that conserves mass, momentum, and energy—is used instead of Koh et al.'s linearized collision operator in consideration of the possibility that the ion distribution function is non-Maxwellian in the steep pedestal. An inaccuracy in Koh et al.'s result is found in the steep edge pedestal that originated from a small error in the collisional momentum conservation. The present study concludes that (1) the bootstrap current in the steep edge pedestal is generally smaller than what has been predicted from the small banana-width (local) approximation [e.g., Sauter et al., Phys. Plasmas 6, 2834 (1999) and Belli et al., Plasma Phys. Controlled Fusion 50, 095010 (2008)], (2) the plasma flow evaluated from the local approximation can significantly deviate from the non-local results, and (3) the bootstrap current in the edge pedestal, where the passing particle region is small, can be dominantly carried by the trapped particles in a broad trapped boundary layer. A new analytic formula based on numerous gyrokinetic simulations using various magnetic equilibria and plasma profiles with self-consistent Grad-Shafranov solutions is constructed.

  1. Contribution to the multi-machine pedestal scaling from COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Komm, Michael; Bílková, Petra; Aftanas, Milan; Berta, Miklós; Böhm, Petr; Bogár, Ondrej; Frassinetti, L.; Grover, Ondřej; Háček, Pavel; Havlíček, Josef; Hron, Martin; Imríšek, Martin; Krbec, Jaroslav; Mitošinková, Klára; Naydenkova, Diana; Pánek, Radomír; Peterka, Matěj; Snyder, P.B.; Stefanikova, E.; Stöckel, Jan; Šos, Miroslav; Urban, Jakub; Varju, Jozef; Vondráček, Petr; Weinzettl, Vladimír

    2017-01-01

    Roč. 57, č. 5 (2017), č. článku 056041. ISSN 0029-5515. [IAEA Fusion Energy Conference (FEC 2016)/26./. Kyoto, 17.10.2016-22.10.2016] R&D Projects: GA ČR(CZ) GA14-35260S; GA ČR(CZ) GA16-14228S; GA MŠk(CZ) 8D15001 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : COMPASS * H-mode * pedestal * scaling * tokamak * HRTS Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 https://doi.org/10.1088/1741-4326/aa6659

  2. Martian Low-Aspect-Ratio Layered Ejecta (LARLE) craters: Distribution, characteristics, and relationship to pedestal craters

    Science.gov (United States)

    Barlow, Nadine G.; Boyce, Joseph M.; Cornwall, Carin

    2014-09-01

    Low-Aspect-Ratio Layered Ejecta (LARLE) craters are a unique landform found on Mars. LARLE craters are characterized by a crater and normal layered ejecta pattern surrounded by an extensive but thin outer deposit which terminates in a sinuous, almost flame-like morphology. We have conducted a survey to identify all LARLE craters ⩾1-km-diameter within the ±75° latitude zone and to determine their morphologic and morphometric characteristics. The survey reveals 140 LARLE craters, with the majority (91%) located poleward of 40°S and 35°N and all occurring within thick mantles of fine-grained deposits which are likely ice-rich. LARLE craters range in diameter from the cut-off limit of 1 km up to 12.2 km, with 83% being smaller than 5 km. The radius of the outer LARLE deposit displays a linear trend with the crater radius and is greatest at higher polar latitudes. The LARLE deposit ranges in length between 2.56 and 14.81 crater radii in average extent, with maximum length extending up to 21.4 crater radii. The LARLE layer is very sinuous, with lobateness values ranging between 1.45 and 4.35. LARLE craters display a number of characteristics in common with pedestal craters and we propose that pedestal craters are eroded versions of LARLE craters. The distribution and characteristics of the LARLE craters lead us to propose that impact excavation into ice-rich fine-grained deposits produces a dusty base surge cloud (like those produced by explosion craters) that deposits dust and ice particles to create the LARLE layers. Salts emplaced by upward migration of water through the LARLE deposit produce a surficial duricrust layer which protects the deposit from immediate removal by eolian processes.

  3. Theory-based model for the pedestal, edge stability and ELMs in tokamaks

    International Nuclear Information System (INIS)

    Pankin, A.Y.; Bateman, G.; Brennan, D.P.; Schnack, D.D.; Snyder, P.B.; Voitsekhovitch, I.; Kritz, A.H.; Janeschitz, G.; Kruger, S.; Onjun, T.; Pacher, G.W.; Pacher, H.D.

    2006-01-01

    An improved model for triggering edge localized mode (ELM) crashes is developed for use within integrated modelling simulations of the pedestal and ELM cycles at the edge of H-mode tokamak plasmas. The new model is developed by using the BALOO, DCON and ELITE ideal MHD stability codes to derive parametric expressions for the ELM triggering threshold. The whole toroidal mode number spectrum is studied with these codes. The DCON code applies to low mode numbers, while the BALOO code applies to only high mode numbers and the ELITE code applies to intermediate and high mode numbers. The variables used in the parametric stability expressions are the normalized pressure gradient and the parallel current density, which drive ballooning and peeling modes. Two equilibria motivated by DIII-D geometry with different plasma triangularities are studied. It is found that the stable region in the high triangularity discharge covers a much larger region of parameter space than the corresponding stability region in the low triangularity discharge. The new ELM trigger model is used together with a previously developed model for pedestal formation and ELM crashes in the ASTRA integrated modelling code to follow the time evolution of the temperature profiles during ELM cycles. The ELM frequencies obtained in the simulations of low and high triangularity discharges are observed to increase with increasing heating power. There is a transition from second stability to first ballooning mode stability as the heating power is increased in the high triangularity simulations. The results from the ideal MHD stability codes are compared with results from the resistive MHD stability code NIMROD

  4. Impact of wall materials and seeding gases on the pedestal and on core plasma performance

    Directory of Open Access Journals (Sweden)

    E. Wolfrum

    2017-08-01

    Full Text Available Plasmas in machines with all metal plasma facing components have a lower Zeff, less radiation cooling in the scrape-off layer and divertor regions and are prone to impurity accumulation in the core. Higher gas puff and the seeding of low-Z impurities are applied to prevent impurity accumulation, to increase the frequency of edge localised modes and to cool the divertor. A lower power threshold for the transition from low-confinement mode to high confinement mode has been found in all metal wall machines when compared to carbon wall machines. The application of lithium before or during discharges can lead to ELM free H-modes. The seeding of high-Z impurities increases core radiation, reduces the power flux across the separatrix and, if applied in the right amount, does not lead to deterioration of the confinement. All these effects have in common that they can often be explained by the shape or position of the density profile. Not only the peakedness of the density profile in the core but also the position of the edge pressure gradient influences global confinement. It is shown how (i ionisation in the pedestal region due to higher reflection of deuterium from high-Z walls, (ii reduced recycling in consequence of lithium wall conditioning, (iii the fostering of edge modes with lithium dropping, (iv increased gas puff and (v the cooling of the scrape-off layer by medium-Z impurities such as nitrogen affect the edge density profile. The consequence is a shift in the pressure profile relative to the separatrix, leading to improved pedestal stability of H-mode plasmas when the direction is inwards.

  5. Reisifirmade TOP 40 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Reisifirmade TOP 40 aastal 2002. Reisifirmade TOP-i esikümme. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Reisifirmade üldandmed. Reisifirmade finantsandmed. Tehnilise käibe alusel arvutatud edetabelid: Reisifirmade TOP 25; Käibe TOP 40; Rentaabluse TOP 10; Käibe kasvu TOP 10

  6. Intergenerational Top Income Persistence

    DEFF Research Database (Denmark)

    Munk, Martin D.; Bonke, Jens; Hussain, M. Azhar

    2016-01-01

    In this paper, we investigate intergenerational top earnings and top income mobility in Denmark. Access to administrative registers allowed us to look at very small fractions of the population. We find that intergenerational mobility is lower in the top when including capital income in the income...... measure— for the rich top 0.1% fathers and sons the elasticity is 0.466. Compared with Sweden, however, the intergenerational top income persistence is about half the size in Denmark....

  7. Volcanic Ash Data Assimilation System for Atmospheric Transport Model

    Science.gov (United States)

    Ishii, K.; Shimbori, T.; Sato, E.; Tokumoto, T.; Hayashi, Y.; Hashimoto, A.

    2017-12-01

    The Japan Meteorological Agency (JMA) has two operations for volcanic ash forecasts, which are Volcanic Ash Fall Forecast (VAFF) and Volcanic Ash Advisory (VAA). In these operations, the forecasts are calculated by atmospheric transport models including the advection process, the turbulent diffusion process, the gravitational fall process and the deposition process (wet/dry). The initial distribution of volcanic ash in the models is the most important but uncertain factor. In operations, the model of Suzuki (1983) with many empirical assumptions is adopted to the initial distribution. This adversely affects the reconstruction of actual eruption plumes.We are developing a volcanic ash data assimilation system using weather radars and meteorological satellite observation, in order to improve the initial distribution of the atmospheric transport models. Our data assimilation system is based on the three-dimensional variational data assimilation method (3D-Var). Analysis variables are ash concentration and size distribution parameters which are mutually independent. The radar observation is expected to provide three-dimensional parameters such as ash concentration and parameters of ash particle size distribution. On the other hand, the satellite observation is anticipated to provide two-dimensional parameters of ash clouds such as mass loading, top height and particle effective radius. In this study, we estimate the thickness of ash clouds using vertical wind shear of JMA numerical weather prediction, and apply for the volcanic ash data assimilation system.

  8. Top quark property measurements in single top

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00386283; The ATLAS collaboration

    2016-01-01

    A review of the recent results on measurements of top quark properties in single top quark processes, performed at the LHC by ATLAS and CMS is presented. The measurements are in good agreement with predictions and no deviations from Standard Model expectations have been observed.

  9. Backprojection of volcanic tremor

    Science.gov (United States)

    Haney, Matthew M.

    2014-01-01

    Backprojection has become a powerful tool for imaging the rupture process of global earthquakes. We demonstrate the ability of backprojection to illuminate and track volcanic sources as well. We apply the method to the seismic network from Okmok Volcano, Alaska, at the time of an escalation in tremor during the 2008 eruption. Although we are able to focus the wavefield close to the location of the active cone, the network array response lacks sufficient resolution to reveal kilometer-scale changes in tremor location. By deconvolving the response in successive backprojection images, we enhance resolution and find that the tremor source moved toward an intracaldera lake prior to its escalation. The increased tremor therefore resulted from magma-water interaction, in agreement with the overall phreatomagmatic character of the eruption. Imaging of eruption tremor shows that time reversal methods, such as backprojection, can provide new insights into the temporal evolution of volcanic sources.

  10. Volcanic eruptions on Io

    Science.gov (United States)

    Strom, R. G.; Schneider, N. M.; Terrile, R. J.; Hansen, C.; Cook, A. F.

    1981-01-01

    Nine eruption plumes which were observed during the Voyager 1 encounter with Io are discussed. During the Voyager 2 encounter, four months later, eight of the eruptions were still active although the largest became inactive sometime between the two encounters. Plumes range in height from 60 to over 300 km with corresponding ejection velocities of 0.5 to 1.0 km/s and plume sources are located on several plains and consist of fissures or calderas. The shape and brightness distribution together with the pattern of the surface deposition on a plume 3 is simulated by a ballistic model with a constant ejection velocity of 0.5 km/s and ejection angles which vary from 0-55 deg. The distribution of active and recent eruptions is concentrated in the equatorial regions and indicates that volcanic activity is more frequent and intense in the equatorial regions than in the polar regions. Due to the geologic setting of certain plume sources and large reservoirs of volatiles required for the active eruptions, it is concluded that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

  11. Using Satellite Observations to Evaluate the AeroCOM Volcanic Emissions Inventory and the Dispersal of Volcanic SO2 Clouds in MERRA

    Science.gov (United States)

    Hughes, Eric J.; Krotkov, Nickolay; da Silva, Arlindo; Colarco, Peter

    2015-01-01

    Simulation of volcanic emissions in climate models requires information that describes the eruption of the emissions into the atmosphere. While the total amount of gases and aerosols released from a volcanic eruption can be readily estimated from satellite observations, information about the source parameters, like injection altitude, eruption time and duration, is often not directly known. The AeroCOM volcanic emissions inventory provides estimates of eruption source parameters and has been used to initialize volcanic emissions in reanalysis projects, like MERRA. The AeroCOM volcanic emission inventory provides an eruptions daily SO2 flux and plume top altitude, yet an eruption can be very short lived, lasting only a few hours, and emit clouds at multiple altitudes. Case studies comparing the satellite observed dispersal of volcanic SO2 clouds to simulations in MERRA have shown mixed results. Some cases show good agreement with observations Okmok (2008), while for other eruptions the observed initial SO2 mass is half of that in the simulations, Sierra Negra (2005). In other cases, the initial SO2 amount agrees with the observations but shows very different dispersal rates, Soufriere Hills (2006). In the aviation hazards community, deriving accurate source terms is crucial for monitoring and short-term forecasting (24-h) of volcanic clouds. Back trajectory methods have been developed which use satellite observations and transport models to estimate the injection altitude, eruption time, and eruption duration of observed volcanic clouds. These methods can provide eruption timing estimates on a 2-hour temporal resolution and estimate the altitude and depth of a volcanic cloud. To better understand the differences between MERRA simulations and volcanic SO2 observations, back trajectory methods are used to estimate the source term parameters for a few volcanic eruptions and compared to their corresponding entry in the AeroCOM volcanic emission inventory. The nature of

  12. Audiitorfirmade TOP 50 aastal 2000

    Index Scriptorium Estoniae

    2001-01-01

    Audiitorfirmade käibe TOP 50, käibe kasvu TOP 25, käibe languse TOP 15, kasumi TOP 50, kasumi kasvu TOP 10, kasumi languse TOP 10, audiitorfirmade finantsnäitajad. Rentaabluse TOP 50, varade tootlikkuse TOP 50

  13. Top Production at LHCb

    CERN Multimedia

    Santana Rangel, Murilo

    2015-01-01

    Single and pair top production in the forward direction at the LHC allows for precision tests of the Standard Model. The observation of top quarks in 7 and 8 TeV data and prospects for precision measurements are shown.

  14. High-frequency coherent edge fluctuations in a high-pedestal-pressure quiescent H-mode plasma.

    Science.gov (United States)

    Yan, Z; McKee, G R; Groebner, R J; Snyder, P B; Osborne, T H; Burrell, K H

    2011-07-29

    A set of high frequency coherent (HFC) modes (f=80-250 kHz) is observed with beam emission spectroscopy measurements of density fluctuations in the pedestal of a strongly shaped quiescent H-mode plasma on DIII-D, with characteristics predicted for kinetic ballooning modes (KBM): propagation in the ion-diamagnetic drift direction; a frequency near 0.2-0.3 times the ion-diamagnetic frequency; inferred toroidal mode numbers of n∼10-25; poloidal wave numbers of k(θ)∼0.17-0.4 cm(-1); and high measured decorrelation rates (τ(c)(-1)∼ω(s)∼0.5×10(6) s(-1)). Their appearance correlates with saturation of the pedestal pressure. © 2011 American Physical Society

  15. Top Physics at Atlas

    CERN Document Server

    Romano, M; The ATLAS collaboration

    2013-01-01

    This talk is an overview of recent results on top-quark physics obtained by the ATLAS collaboration from the analysis of p-p collisions at 7 and 8 TeV at the Large Hadron Collider. Total and differential top pair cross section, single top cross section and mass measurements are presented.

  16. A novel technique for real-time estimation of edge pedestal density gradients via reflectometer time delay data

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, L., E-mail: zeng@fusion.gat.com; Doyle, E. J.; Rhodes, T. L.; Wang, G.; Sung, C.; Peebles, W. A. [Physics and Astronomy Department, University of California, Los Angeles, California 90095 (United States); Bobrek, M. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6006 (United States)

    2016-11-15

    A new model-based technique for fast estimation of the pedestal electron density gradient has been developed. The technique uses ordinary mode polarization profile reflectometer time delay data and does not require direct profile inversion. Because of its simple data processing, the technique can be readily implemented via a Field-Programmable Gate Array, so as to provide a real-time density gradient estimate, suitable for use in plasma control systems such as envisioned for ITER, and possibly for DIII-D and Experimental Advanced Superconducting Tokamak. The method is based on a simple edge plasma model with a linear pedestal density gradient and low scrape-off-layer density. By measuring reflectometer time delays for three adjacent frequencies, the pedestal density gradient can be estimated analytically via the new approach. Using existing DIII-D profile reflectometer data, the estimated density gradients obtained from the new technique are found to be in good agreement with the actual density gradients for a number of dynamic DIII-D plasma conditions.

  17. Effect of soil-structure interaction on the seismic behaviour of pedestal-structure system in large dish antennas

    Directory of Open Access Journals (Sweden)

    Bahador Pourhatami

    2017-12-01

    Full Text Available Regarding the progressive improvement in the territory of Space Technology in all developed countries and consequently developing countries including Islamic Republic of Iran, the optimization of design and utilization of the communication equipment has been paid more attention today. For instance, considering recent highly innovative methods, specifically in communication field, developed for design, manufacturing and exploiting dish antenna for specific cases, cooperation of other science and technology experts, like civil engineers, is also necessary. In this way, more delicate design procedure in order to satisfy communication requirement, is achieved. So far, no specific investigation about aforementioned subject, especially the effect of soil-structure interaction (SSI in analysing the seismic behaviour of communication large dish antennas has been conducted in Iran. In this paper, with the aim of investigating the effect of SSI on seismic behavior of pedestal, first an acceptable range for antenna displacement – as the most important parameter in pedestal structure for antenna – in both operational and survival states, has been calculated numerically based on generic formula. Secondly, the modelling of the whole pedestal-structure system has been modelled subjected to the associated loads and other primary conditions. This procedure has been performed once without considering the SSI and once more with it. Comparison of the obtained results shows that considering the SSI would impress the output results with a difference rate more than 50% and 600% respectively at survival and operational condition.

  18. Integrated predictive modeling of high-mode tokamak plasmas using a combination of core and pedestal models

    International Nuclear Information System (INIS)

    Bateman, Glenn; Bandres, Miguel A.; Onjun, Thawatchai; Kritz, Arnold H.; Pankin, Alexei

    2003-01-01

    A new integrated modeling protocol is developed using a model for the temperature and density pedestal at the edge of high-mode (H-mode) plasmas [Onjun et al., Phys. Plasmas 9, 5018 (2002)] together with the Multi-Mode core transport model (MMM95) [Bateman et al., Phys. Plasmas 5, 1793 (1998)] in the BALDUR integrated modeling code to predict the temperature and density profiles of 33 H-mode discharges. The pedestal model is used to provide the boundary conditions in the simulations, once the heating power rises above the H-mode power threshold. Simulations are carried out for 20 discharges in the Joint European Torus and 13 discharges in the DIII-D tokamak. These discharges include systematic scans in normalized gyroradius, plasma pressure, collisionality, isotope mass, elongation, heating power, and plasma density. The average rms deviation between experimental data and the predicted profiles of temperature and density, normalized by central values, is found to be about 10%. It is found that the simulations tend to overpredict the temperature profiles in discharges with low heating power per plasma particle and to underpredict the temperature profiles in discharges with high heating power per particle. Variations of the pedestal model are used to test the sensitivity of the simulation results

  19. CDF Top Physics

    Science.gov (United States)

    Tartarelli, G. F.; CDF Collaboration

    1996-05-01

    The authors present the latest results about top physics obtained by the CDF experiment at the Fermilab Tevatron collider. The data sample used for these analysis (about 110 pb{sup{minus}1}) represents almost the entire statistics collected by CDF during four years (1992--95) of data taking. This large data size has allowed detailed studies of top production and decay properties. The results discussed here include the determination of the top quark mass, the measurement of the production cross section, the study of the kinematics of the top events and a look at top decays.

  20. Integrated simulation of ELM energy loss determined by pedestal MHD and SOL transport

    International Nuclear Information System (INIS)

    Hayashi, N.; Takizuka, T.; Ozeki, T.; Aiba, N.; Oyama, N.

    2007-01-01

    An integrated simulation code TOPICS-IB based on a transport code with a stability code for the peeling-ballooning modes and a scrape-off-layer (SOL) model has been developed to clarify self-consistent effects of edge localized modes (ELMs) and the SOL on the plasma performance. Experimentally observed collisionality dependence of the ELM energy loss is found to be caused by both the edge bootstrap current and the SOL transport. The bootstrap current decreases with an increase in collisionality and intensifies the magnetic shear at the pedestal region. The increase in the magnetic shear reduces the width of eigenfunctions of unstable modes, which results in the reduction of both the area of the ELM enhanced transport and the ELM enhanced transport near the separatrix. On the other hand, when an ELM crash occurs, the energy flows into the SOL and the SOL temperature rapidly increases. The increase in the SOL temperature lowers the ELM energy loss due to the flattening of the radial edge gradient. The parallel electron heat conduction determines how the SOL temperature increases. For higher collisionality, the conduction becomes lower and the SOL electron temperature increases more. By the above two mechanisms, the ELM energy loss decreases with increasing collisionality

  1. Plasma current dependence of the edge pedestal height in JET ELM-free H-modes

    International Nuclear Information System (INIS)

    Nave, M.F.F; Lomas, P.; Gowers, C.; Guo, H.; Hawkes, N.; Huysmans, G.T.A.; Jones, T.; Parail, V.V.; Rimini, F.; Schunke, B.

    2000-01-01

    Some models for the suppression of turbulence in the L to H transition, suggest that the width of the H-mode edge barrier is either proportional or is of the order of the thermal or the fast-ion poloidal Larmor radius. This would require that the width of the edge barrier should depend on the plasma current. This dependence has been clearly verified at JET in experiments designed to control the edge MHD stability of ELM-free hot-ion H-mode plasmas. The effects of isotopic mass and the applicability of several edge barrier models to the hot-ion H-mode plasmas were analysed in (Guo H Y et al 2000 Edge transport barrier in JET hot-ion H-modes Nucl. Fusion 40 69) using a large database containing both deuterium-only and deuterium-tritium plasmas. This database has now been enlarged to include discharges from a plasma shape scan, allowing one to study the dependence of the pedestal height on the edge shear. In addition, the range of plasma currents was extended up to 6 MA. It is shown that the edge data are best described by a model where the edge barrier width is determined by the fast ions weighted towards the components with largest poloidal Larmor radii. However, it is not possible to conclusively eliminate the thermal ion model. (author)

  2. H-mode pedestal characteristics in ITER shape discharges on DIII-D

    International Nuclear Information System (INIS)

    Osborne, T.H.; Burrell, K.H.; Groebner, R.J.

    1998-09-01

    Characteristics of the H-mode pedestal are studied in Type 1 ELM discharges with ITER cross-sectional shape and aspect ratio. The scaling of the width of the edge step gradient region, δ, which is most consistent with the data is with the normalized edge pressure, (β POL PED ) 0.4 . Fits of δ to a function of temperature, such as ρ POL , are ruled out in divertor pumping experiments. The edge pressure gradient is found to scale as would be expected from infinite n ballooning mode theory; however, the value of the pressure gradient exceeds the calculated first stable limit by more than a factor of 2 in some discharges. This high edge pressure gradient is consistent with access to the second stable regime for ideal ballooning for surfaces near the edge. In lower q discharges, including discharges at the ITER value of q, edge second stability requires significant edge current density. Transport simulations give edge bootstrap current of sufficient magnitude to open second stable access in these discharges. Ideal kink analysis using current density profiles including edge bootstrap current indicate that before the ELM these discharges may be unstable to low n, edge localized modes

  3. Pedestal characteristics and MHD stability of H-mode plasmas in TCV

    International Nuclear Information System (INIS)

    Pitzschke, A.

    2011-01-01

    temperature profile during the ELM cycle, the low repetition rate of the lasers used for Thomson scattering is a limiting. Although the system on TCV comprises 3 laser units that may be triggered in sequence with time separations down to 1 ms, time evolution over longer periods can only be reconstructed from repetitive events. In this context, an adjustment of the laser trigger to improve the synchronization with the ELM event is an advantage. A method was developed and implemented to generate a synchronizing trigger sequence, by a real-time monitoring of the D-alpha emission, which provides a marker for the ELM event. Recently, a ‘snowflake’ (SF) divertor configuration, proposed as a possible solution to reduce the plasma-wall interaction by changing the divertor’s poloidal magnetic field topology, was generated, for the first time, in TCV. A numerical code (KINX), based on a magnetohydrodynamic model (ideal MHD), was used to investigate the stability limits of this configuration under H-mode conditions and compare them with a similar standard single-null equilibrium. In a series of experiments, improved energy confinement was found and explained by improved stability of the edge region in the SF configuration. The influence of the pedestal structure in ELMy H-mode plasmas on the energy confinement and on ELM energy losses was investigated. The different ELM regimes found in TCV were analyzed, in particular the transition between type-III to type-I ELMs. The operational boundary of each ELM regime was characterized and verified by ideal MHD stability simulations for the ETB region. Recent studies on the scaling of the pedestal width with normalized poloidal pressure were confirmed. Using the capabilities of TCV, the influence of plasma shaping on pedestal parameters and MHD stability limits was investigated. In the past, models were developed to describe the onset of type-I ELMs, which are associated with modes in the ETB region arising from a coupling of pressure- and

  4. Global gyrokinetic simulations of the H-mode tokamak edge pedestal

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Weigang; Parker, Scott E.; Chen, Yang [Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Groebner, Richard J. [General Atomics, Post Office Box 85068, San Diego, California 92186 (United States); Yan, Zheng [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Pankin, Alexei Y.; Kruger, Scott E. [Tech-X Corporation, 5621 Arapahoe Ave., Boulder, Colorado 80305 (United States)

    2013-05-15

    Global gyrokinetic simulations of DIII-D H-mode edge pedestal show two types of instabilities may exist approaching the onset of edge localized modes: an intermediate-n, high frequency mode which we identify as the “kinetic peeling ballooning mode (KPBM),” and a high-n, low frequency mode. Our previous study [W. Wan et al., Phys. Rev. Lett. 109, 185004 (2012)] has shown that when the safety factor profile is flattened around the steep pressure gradient region, the high-n mode is clearly kinetic ballooning mode and becomes the dominant instability. Otherwise, the KPBM dominates. Here, the properties of the two instabilities are studied by varying the density and temperature profiles. It is found that the KPBM is destabilized by density and ion temperature gradient, and the high-n mode is mostly destabilized by electron temperature gradient. Nonlinear simulations with the KPBM saturate at high levels. The equilibrium radial electric field (E{sub r}) reduces the transport. The effect of the parallel equilibrium current is found to be weak.

  5. Multilayered pyramidal dissolving microneedle patches with flexible pedestals for improving effective drug delivery.

    Science.gov (United States)

    Lau, Shinying; Fei, Jie; Liu, Haoran; Chen, Weixing; Liu, Ran

    2017-11-10

    Dissolving microneedles have been employed as a safe and convenient transdermal delivery system for drugs and vaccines. To improve effective drug delivery, a multilayered pyramidal dissolving microneedle patch, composed of silk fibroin tips with the ability of robust mechanical strength, rapid dissolution and drug release supported on a flexible polyvinyl alcohol (PVA) pedestal is reported. To show the utility of this approach the ability of the fabricated microneedles to deliver insulin is demonstrated. The dissolving microneedles have sufficient mechanical strength to be inserted into abdomen skin of mice to a depth of approximately 150μm, and release their encapsulated insulin into the skin to cause a hypoglycemic effect. The fabrication of microneedles avoids high temperature which benefits storage stability at room temperature for 20d. This result indicates >99.4% of insulin remained in the microneedles. In comparison to traditional needle-based administration, the proposed multilayered pyramidal dissolving microneedle patches enable self-administration, miniaturization, pain-free administration, drug delivery and drug stability, all being important features in needle free drug delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Plasma current dependence of the edge pedestal height in JET ELM-free H-modes

    International Nuclear Information System (INIS)

    Nave, M.; Lomas, P.; Gowers, C.

    2000-01-01

    Models for the suppression of turbulence in the L to H transition, suggest that the width of the H-mode edge barrier is either proportional or is of the order of the ion poloidal Larmor radius. This would require that the width of the edge barrier should depend on the plasma current. This dependence has been clearly verified at JET in experiments designed to control the edge MHD stability of ELM-free hot-ion H-mode plasmas. The effects of isotopic mass and the applicability of several edge barrier models to the hot-ion H-mode plasmas were analysed in using a large database containing both Deuterium-only (DD) and Deuterium-Tritium (DT) plasmas. This database has now been enlarged to include discharges from a plasma shape scan, allowing to study the dependence of the pedestal height on the edge shear. In addition the range of plasma currents was extended up to 6 MA. It is shown that the edge data is best described by a model where the edge barrier width is determined by the fast ions weighted towards the components with largest poloidal Larmor radii. However, it is not possible to eliminate conclusively the thermal ion model. (author)

  7. Volcanic risk; Risque volcanique

    Energy Technology Data Exchange (ETDEWEB)

    Rancon, J.P.; Baubron, J.C.

    1995-12-31

    This project follows the previous multi-disciplinary studies carried out by the French Bureau de Recherches Geologiques et Minieres (BRGM) on the two active volcanoes of the French lesser Antilles: Mt Pelee (Martinique) and Soufriere (Guadeloupe) for which geological maps and volcanic risk studies have been achieved. The research program comprises 5 parts: the study of pyroclastic deposits from recent eruptions of the two volcanoes for a better characterization of their eruptive phenomenology and a better definition of crisis scenarios; the study of deposits and structures of active volcanoes from Central America and the study of eruptive dynamics of andesite volcanoes for a transposition to Antilles` volcanoes; the starting of a methodological multi-disciplinary research (volcanology, geography, sociology...) on the volcanic risk analysis and on the management of a future crisis; and finally, the development of geochemical survey techniques (radon, CO{sub 2}, H{sub 2}O) on active volcanoes of Costa-Rica and Europe (Fournaise, Furnas, Etna) and their application to the Soufriere. (J.S.). 9 refs., 3 figs.

  8. Volcanic Eruptions and Climate

    Science.gov (United States)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

    Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

  9. Turismifirmade 2000. a. TOP 30

    Index Scriptorium Estoniae

    2001-01-01

    Turismiettevõtete üldandmed: turismiettevõtete finantsnäitajad; käibe TOP 30; käibe kasvu TOP 10; kasumi TOP 20; kasumi kasvu TOP 10; kasumi languse TOP; rentaabluse TOP 10; varade tootlikkuse TOP 10

  10. Ehitusmaterjalitootjate TOP 70 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Ilmunud ka: Delovõje Vedomosti : Stroitelstvo, 29. sept. 2004, lk. 2,4. Ehitusmaterjalitootjate TOP 70; Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP. Ehitusmaterjalitootjate üldandmed

  11. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  12. TOP LINAC design; Progetto del TOP LINAC

    Energy Technology Data Exchange (ETDEWEB)

    Picardi, L; Ronsivalle, C; Vignati, A [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione

    1997-11-01

    The report describes a linear accelerator for protons named TOP LINAC designed for the TOP (Terapia Oncologica con Protoni, Oncological Protontherapy) project launched by the Italian National Institute of Health (Istituto Superiore di Sanita`, ISS) to explore in collaboration with the biggest Oncological Hospital in Rome (Istituto Regina Elena, IRE) the potentialities of the therapy with accelerated protons and establish guide lines for the application of this new type of radiotherapy in comparison with the more traditional electron and x-rays radiotherapy. The concept of a compact accelerator for protontherapy applications bore within the Italian Hadrontherapy Collaboration (TERA Collaboration) with the aim to diffuse the protontherapy on the National territory. The ISS program plans to use the TOP linac proton beam also for production of PET (Positron Emission Tomography) radioisotopes and radiobiology studies. Official agreements are in course between ISS and ENEA which provides its experience in the industrial and medical accelerators for the design and the construction of the TOP linac. The accelerator that will be the first 3 GHz proton linac in the world, will be composed of a 428.3 MHz 7 Me V RFQ + DTL injector followed by a 7-65 Me V section of a 3 GHz SCDTL structure and a 65 - 200 Me V variable energy SCL 3 GHz structure. In particular the SCDTL section uses a highly innovative accelerating structure patented by ENEA. In this report the clinical and physical requests are discussed and a preliminary design of the whole machine is given.

  13. Ekspedeerimisettevõtete TOP 50

    Index Scriptorium Estoniae

    2006-01-01

    Ilmunud ka: Delovõje Vedomosti : Transport i Logistika nr. 11, 29. nov. lk. 32-35. Ekspedeerimisettevõtete TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumikasvu TOP 10; Rentaabluse TOP 10; ROE TOP 10; Ekspedeerimisettevõtete üld- ja finantsandmed. Ajal. Delovõje Vedomosti : Transport i Logistika toodud ainult Ekspedeerimisettevõtete TOP 50

  14. Correlations between quasi-coherent fluctuations and the pedestal evolution during the inter-edge localized modes phase on DIII-D

    International Nuclear Information System (INIS)

    Diallo, A.; Battaglia, D. J.; Guttenfelder, W.; Groebner, R. J.; Osborne, T. H.; Snyder, P. B.; Rhodes, T. L.; Smith, D. R.; Canik, J. M.

    2015-01-01

    Direct measurements of the pedestal recovery during an edge-localized mode cycle provide evidence that quasi-coherent fluctuations (QCFs) play a role in the inter-ELM pedestal dynamics. Using fast Thomson scattering measurements, the pedestal density and temperature evolutions are probed on sub-millisecond time scales to show a fast recovery of the density gradient compared to the temperature gradient. The temperature gradient appears to provide a drive for the onset of quasi-coherent fluctuations (as measured with the magnetic probe and the density diagnostics) localized in the pedestal. The amplitude evolution of these QCFs tracks the temperature gradient evolution including its saturation. Such correlation suggests that these QCFs play a key role in limiting the pedestal temperature gradient. The saturation of the QCFs coincides with the pressure gradient reaching the kinetic-ballooning mode (KBM) critical gradient as predicted by EPED1. Furthermore, linear microinstability analysis using GS2 indicates that the steep gradient is near the KBM threshold. Thus, the modeling and the observations together suggest that QCFs are consistent with dominant KBMs, although microtearing cannot be excluded as subdominant

  15. Correlations between quasi-coherent fluctuations and the pedestal evolution during the inter-edge localized modes phase on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, A.; Battaglia, D. J.; Guttenfelder, W. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Groebner, R. J.; Osborne, T. H.; Snyder, P. B. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Rhodes, T. L. [Physics and Astronomy Department, P.O. Box 957099, Los Angeles, California 90095-7099 (United States); Smith, D. R. [Department of Engineering Physics, 1500 Engineering Dr., Madison, Wisconsin 53706 (United States); Canik, J. M. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)

    2015-05-15

    Direct measurements of the pedestal recovery during an edge-localized mode cycle provide evidence that quasi-coherent fluctuations (QCFs) play a role in the inter-ELM pedestal dynamics. Using fast Thomson scattering measurements, the pedestal density and temperature evolutions are probed on sub-millisecond time scales to show a fast recovery of the density gradient compared to the temperature gradient. The temperature gradient appears to provide a drive for the onset of quasi-coherent fluctuations (as measured with the magnetic probe and the density diagnostics) localized in the pedestal. The amplitude evolution of these QCFs tracks the temperature gradient evolution including its saturation. Such correlation suggests that these QCFs play a key role in limiting the pedestal temperature gradient. The saturation of the QCFs coincides with the pressure gradient reaching the kinetic-ballooning mode (KBM) critical gradient as predicted by EPED1. Furthermore, linear microinstability analysis using GS2 indicates that the steep gradient is near the KBM threshold. Thus, the modeling and the observations together suggest that QCFs are consistent with dominant KBMs, although microtearing cannot be excluded as subdominant.

  16. Top Quark Physics

    International Nuclear Information System (INIS)

    Larios, F.

    2006-01-01

    We give an overview of the physics of the Top quark, from the experimental discovery to the studies of its properties. We review some of the work done on the Electroweak and Flavor Changing couplings associated with the Top quark in the Standard Model and beyond. We will focus on the specific contribution of phycisits working in Mexico and Mexican physicists working abroad

  17. Top quark theory

    NARCIS (Netherlands)

    Laenen, E.

    2012-01-01

    The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.

  18. Closer look at lunar volcanism

    International Nuclear Information System (INIS)

    Vaniman, D.T.; Heiken, G.; Taylor, G.J.

    1984-01-01

    Although the American Apollo and Soviet Luna missions concentrated on mare basalt samples, major questions remain about lunar volcanism. Lunar field work will be indispensable for resolving the scientific questions about ages, compositions, and eruption processes of lunar volcanism. From a utilitarian standpoint, a better knowledge of lunar volcanism will also yield profitable returns in lunar base construction (e.g., exploitation of rille or lava-tube structures) and in access to materials such as volatile elements, pure glass, or ilmenite for lunar industry

  19. The H-mode pedestal, ELMs and TF ripple effects in JT-60U/JET dimensionless identity experiments

    International Nuclear Information System (INIS)

    Saibene, G.; Oyama, N.; Loennroth, J.; Andrew, Y.; Luna, E. de la; Giroud, C.; Huysmans, G.T.A.; Kamada, Y.; Kempenaars, M.A.H.; Loarte, A.; Donald, D. Mc; Nave, M.M.F.; Meiggs, A.; Parail, V.; Sartori, R.; Sharapov, S.; Stober, J.; Suzuki, T.; Takechi, M.; Toi, K.; Urano, H.

    2007-01-01

    This paper summarizes results of dimensionless identity experiments in JT-60U and JET, aimed at the comparison of the H-mode pedestal and ELM behaviour in the two devices. Given their similar size, dimensionless matched plasmas are also similar in their dimensional parameters (in particular, the plasma minor radius a is the same in JET and JT-60U). Power and density scans were carried out at two values of I p , providing a q scan (q 95 = 3.1 and 5.1) with fixed (and matched) toroidal field. Contrary to initial expectations, a dimensionless match between the two devices was quite difficult to achieve. In general, p ped in JT-60U is lower than in JET and, at low q, the pedestal pressure of JT-60U with a Type I ELMy edge is matched in JET only in the Type III ELM regime. At q 95 = 5.1, a dimensionless match in ρ*, ν* and β p,ped is obtained with Type I ELMs, but only with low power JET H-modes. These results motivated a closer investigation of experimental conditions in the two devices, to identify possible 'hidden' physics that prevents obtaining a good match of pedestal values over a large range of plasmas parameters. Ripple-induced ion losses of the medium bore plasma used in JT-60U for the similarity experiments are identified as the main difference with JET. The magnitude of the JT-60U ripple losses is sufficient to induce counter-toroidal rotation in co-injected plasma. The influence of ripple losses was demonstrated at q 95 = 5.1: reducing ripple losses by ∼2 (from 4.3 to 1.9 MW) by replacing positive with negative neutral beam injection at approximately constant P in resulted in an increased p ped in JT-60U, providing a good match to full power JET H-modes. At the same time, the counter-toroidal rotation decreased. Physics mechanisms relating ripple losses to pedestal performance are not yet identified, and the possible role of velocity shear in the pedestal stability, as well as the possible influence of ripple on thermal ion transport are briefly

  20. Top physics at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.E. [Univ. of Rochester, NY (United States)

    1997-01-01

    We report on top physics results using a 100 pb{sup -1} data sample of p{bar p} collisions at {radical}s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). We have identified top signals in a variety of decay channels, and used these channels to extract a measurement of the top mass and production cross section. A subset of the data (67 pb{sup -1}) is used to determine M{sub top} = 176 {+-} 8(stat) {+-} 10(syst) and {sigma}(tt) = 7.6 {sub -2.0}{sup +2.4} pb. We present studies of the kinematics of t{bar t} events and extract the first direct measurement of V{sub tb}. Finally, we indicate prospects for future study of top physics at the Tevatron.

  1. Top Quark Mass

    CERN Document Server

    Mulders, Martijn

    2016-01-01

    Ever since the discovery of the top quark at the Tevatron collider in 1995 the measurement of its mass has been a high priority. As one of the fundamental parameters of the Standard Theory of particle physics, the precise value of the top quark mass together with other inputs provides a test for the self-consistency of the theory, and has consequences for the stability of the Higgs field that permeates the Universe. In this review I will briefly summarize the experimental techniques used at the Tevatron and the LHC experiments throughout the years to measure the top quark mass with ever improving accuracy, and highlight the recent progress in combining all measurements in a single world average combination. As experimental measurements became more precise, the question of their theoretical interpretation has become important. The difficulty of relating the measured quantity to the fundamental top mass parameter has inspired alternative measurement methods that extract the top mass in complementary ways. I wil...

  2. Edge localized modes and edge pedestal in NBI and ICRF heated H, D and T-plasmas in JET

    International Nuclear Information System (INIS)

    Bhatnagar, V.; Lingertat, J.; Barnsley, R.

    1998-12-01

    Based on experiments carried out in JET in D:T mixtures varying from 100:0 to 5:95 and those carried out in hydrogen plasmas, the isotopic mass dependence of ELM parameters and the edge pedestal pressure in neutral beam (NBI) and ion cyclotron resonance (ICRF) heated H-mode plasmas is presented. The ELM frequency is found to decrease with the atomic mass number both in ICRH and NBI discharges. However, the frequency in the case of ICRH is about 8 - 10 times higher than in the NBI case. Assuming that ELMs occur at a critical edge pressure gradient, limited by the ballooning instability, the scaling of the maximum edge pressure is most consistent with the assumption that the width of the transport barrier scales as the ion poloidal Larmor radius governed by the average energy of fast ions at the edge. The critical edge pressure in NBI heated discharges increases with the isotopic mass which. is consistent with the higher deduced width of the edge transport, barrier in tritium than in deuterium and hydrogen. The critical edge pressure in ICRH discharges is smaller, presumably, due to the smaller fast-ion contribution to the edge region. As a consequence of the edge pressure scaling with isotopic mass, the edge operational space in the n e - T e diagram increases with operation in tritium. If the evidence that the edge pedestal width is governed by the average energy of fast ions in the edge prevails, the pedestal in ITER would be controlled by the slowing down energy spectrum of α-particles in the edge. (author)

  3. The effects of the pedestal/floor interface on the dynamic characteristics of the storage ring girder support assemblies

    International Nuclear Information System (INIS)

    Jendrzejczyk, J.A.; Chen, S.S.; Zhu, S.; Mangra, D.; Smith, R.K.

    1993-05-01

    To avoid unacceptable vibration of the storage ring quadrupoles, and to ensure that the established vibration criteria are satisfied, the philosophy from inception of the APS has been (1) to locate and design the machine to minimize motion of the storage ring basemat and, (2) following construction, to monitor machine operation and user experiments to ensure that vibration sources are not introduced. This report addresses the design of the storage ring girder support assemblies, and, specifically, the effect of the pedestal/floor interface on the dynamic characteristics (i.e., resonant frequencies, damping, and mode shape)

  4. Volcanology: Volcanic bipolar disorder explained

    Science.gov (United States)

    Jellinek, Mark

    2014-02-01

    Eruptions come in a range of magnitudes. Numerical simulations and laboratory experiments show that rare, giant super-eruptions and smaller, more frequent events reflect a transition in the essential driving forces for volcanism.

  5. Lidar sounding of volcanic plumes

    Science.gov (United States)

    Fiorani, Luca; Aiuppa, Alessandro; Angelini, Federico; Borelli, Rodolfo; Del Franco, Mario; Murra, Daniele; Pistilli, Marco; Puiu, Adriana; Santoro, Simone

    2013-10-01

    Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on remote sensing of volcanic plumes, reports on the current progress of the lidar system.

  6. Active Volcanic Eruptions on Io

    Science.gov (United States)

    1996-01-01

    Six views of the volcanic plume named Prometheus, as seen against Io's disk and near the bright limb (edge) of the satellite by the SSI camera on the Galileo spacecraft during its second (G2) orbit of Jupiter. North is to the top of each frame. To the south-southeast of Prometheus is another bright spot that appears to be an active plume erupting from a feature named Culann Patera. Prometheus was active 17 years ago during both Voyager flybys, but no activity was detected by Voyager at Culann. Both of these plumes were seen to glow in the dark in an eclipse image acquired by the imaging camera during Galileo's first (G1) orbit, and hot spots at these locations were detected by Galileo's Near-Infrared Mapping Spectrometer.The plumes are thought to be driven by heating sulfur dioxide in Io's subsurface into an expanding fluid or 'geyser'. The long-lived nature of these eruptions requires that a substantial supply of sulfur dioxide must be available in Io's subsurface, similar to groundwater. Sulfur dioxide gas condenses into small particles of 'snow' in the expanding plume, and the small particles scatter light and appear bright at short wavelengths. The images shown here were acquired through the shortest-wavelength filter (violet) of the Galileo camera. Prometheus is about 300 km wide and 75 km high and Culann is about 150 km wide and less than 50 km high. The images were acquired on September 4, 1996 at a range of 2,000,000 km (20 km/pixel resolution). Prometheus is named after the Greek fire god and Culann is named after the Celtic smith god.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can

  7. Top quark mass measurement

    International Nuclear Information System (INIS)

    Maki, Tuula; Helsinki Inst. of Phys.; Helsinki U. of Tech.

    2008-01-01

    The top quark is the heaviest elementary particle. Its mass is one of the fundamental parameters of the standard model of particle physics, and an important input to precision electroweak tests. This thesis describes three measurements of the top-quark mass in the dilepton decay channel. The dilepton events have two neutrinos in the final state; neutrinos are weakly interacting particles that cannot be detected with a multipurpose experiment. Therefore, the signal of dilepton events consists of a large amount of missing energy and momentum carried off by the neutrinos. The top-quark mass is reconstructed for each event by assuming an additional constraint from a top mass independent distribution. Template distributions are constructed from simulated samples of signal and background events, and parameterized to form continuous probability density functions. The final top-quark mass is derived using a likelihood fit to compare the reconstructed top mass distribution from data to the parameterized templates. One of the analyses uses a novel technique to add top mass information from the observed number of events by including a cross-section-constraint in the likelihood function. All measurements use data samples collected by the CDF II detector

  8. Volcanic eruption plumes on Io

    International Nuclear Information System (INIS)

    Strom, R.G.; Terrile, R.J.; Masursky, H.; Hansen, C.

    1979-01-01

    The detection of an umbrella-shaped plume extending about 280 km above the bright limb of Io was one of the most important discoveries made during the Voyager 1 encounter with the jovian system. This discovery proves that Io is volcanically active at present, and the number and magnitude of these eruptions indicate that Io is the most volcanically active body so far discovered in the Solar System. Preliminary analyses of these eruptive plumes are presented. (U.K.)

  9. Volcanic hazards and aviation safety

    Science.gov (United States)

    Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,

    1996-01-01

    An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by volcanic debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that volcanic hazards pose to aircraft and improves aviation safety.

  10. Influence of gold nanoparticles on the 805 nm gain in Tm3+/Yb3+ codoped PbO-GeO2 pedestal waveguides

    Science.gov (United States)

    de Assumpção, T. A. A.; Camilo, M. E.; Alayo, M. I.; da Silva, D. M.; Kassab, L. R. P.

    2017-10-01

    The production and characterization of pedestal waveguides based on PbO-GeO2 amorphous thin films codoped with Tm3+/Yb3+, with and without gold nanoparticles (NPs), are reported. Pedestal structure was obtained by conventional photolithography and plasma etching. Tm3+/Yb3+ codoped PGO amorphous thin film was obtained by RF Magnetron Sputtering deposition and used as core layer in the pedestal optical waveguide. The minimum propagation losses in the waveguide were 3.6 dB/cm at 1068 nm. The internal gain at 805 nm was enhanced and increased to 8.67 dB due to the presence of gold NPs. These results demonstrate for the first time that Tm3+/Yb3+ codoped PbO-GeO2 waveguides are promising for first telecom window and integrated photonics, especially for applications on fiber network at short distances.

  11. Semi-analytical study of the tokamak pedestal density profile in a single-null diverted plasma with puffing-recycling gas sources

    Science.gov (United States)

    Shi, Bingren

    2010-10-01

    The tokamak pedestal density structure is generally studied using a diffusion-dominant model. Recent investigations (Stacey and Groebner 2009 Phys. Plasmas 16 102504) from first principle based physics have shown a plausible existence of large inward convection in the pedestal region. The diffusion-convection equation with rapidly varying convection and diffusion coefficients in the near edge region and model puffing-recycling neutral particles is studied in this paper. A peculiar property of its solution for the existence of the large convection case is that the pedestal width of the density profile, qualitatively different from the diffusion-dominant case, depends mainly on the width of the inward convection and only weakly on the neutral penetration length and its injection position.

  12. Semi-analytical study of the tokamak pedestal density profile in a single-null diverted plasma with puffing-recycling gas sources

    Energy Technology Data Exchange (ETDEWEB)

    Shi Bingren, E-mail: shibr@swip.ac.c [Southwestern Institute of Physics, PO Box 432, Chengdu, Sichuan 610041 (China)

    2010-10-15

    The tokamak pedestal density structure is generally studied using a diffusion-dominant model. Recent investigations (Stacey and Groebner 2009 Phys. Plasmas 16 102504) from first principle based physics have shown a plausible existence of large inward convection in the pedestal region. The diffusion-convection equation with rapidly varying convection and diffusion coefficients in the near edge region and model puffing-recycling neutral particles is studied in this paper. A peculiar property of its solution for the existence of the large convection case is that the pedestal width of the density profile, qualitatively different from the diffusion-dominant case, depends mainly on the width of the inward convection and only weakly on the neutral penetration length and its injection position.

  13. Volcanic crisis in

    Directory of Open Access Journals (Sweden)

    Mgs. Víctor Manuel Pérez Martínez

    2007-01-01

    Full Text Available The article is the result of an investigation which is focussed on some deontological aspects of the scientificjournalism. In the first place it gives a theoretical vision about science, journalism, internet and including some reflectionsabout the deontological principles in handling the information about science and technology. This focus is useful as it formsthe base of an investigation where we deal with the information about a possible ”volcanic crisis” in El Teide during the years2004-2005 done by the digital newspaper” El Dïa” a canarian newspaper from Tenerife. The work required the revision of theinformation which was published and a followed analysis of its context. It was used the digital version with the purpose ofvisualizing the news which was published. It was also compared with a printed version, with local cover but divulged theinformation to the public who was most affected by this particular news. The results give rise to some questions regardinghow the information is given to a topic which is of local interest as well as national and international interest due to therepercussions in the social, economical and tourist field (the tourist field is the main industrial sector in Tenerife by receivingthis type of news.

  14. Top physics in WHIZARD

    Energy Technology Data Exchange (ETDEWEB)

    Reuter, Juergen; Chokoufe Nejad, Bijan [DESY, Hamburg (Germany). Theory Group; Bach, Fabian [European Commission, Eurostat, Luxembourg (Luxembourg); Hoang, Andre [Vienna Univ. (Austria). Faculty of Physics; Vienna Univ. (Austria). Erwin Schroedinger International Inst. for Mathematical Physics; Kilian, Wolfgang [Siegen Univ. (Germany); Stahlhofen, Maximilian [Mainz Univ. (Germany). PRISMA Cluster of Excellence; Teubner, Thomas [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Weiss, Christian [DESY, Hamburg (Germany). Theory Group; Siegen Univ. (Germany)

    2016-03-15

    In this talk we summarize the top physics setup in the event generator WHIZARD with a main focus on lepton colliders. This includes full six-, eight- and ten-fermion processes, factorized processes and spin correlations. For lepton colliders, QCD NLO processes for top quark physics are available and discussed. A special focus is on the top-quark pair threshold, where a special implementation combines a non-relativistic effective field theory calculation augmented by a next-to-leading threshold logarithm resummation with a continuum relativistic fixed-order QCD NLO simulation.

  15. Top physics in WHIZARD

    International Nuclear Information System (INIS)

    Reuter, Juergen; Chokoufe Nejad, Bijan; Hoang, Andre; Stahlhofen, Maximilian

    2016-03-01

    In this talk we summarize the top physics setup in the event generator WHIZARD with a main focus on lepton colliders. This includes full six-, eight- and ten-fermion processes, factorized processes and spin correlations. For lepton colliders, QCD NLO processes for top quark physics are available and discussed. A special focus is on the top-quark pair threshold, where a special implementation combines a non-relativistic effective field theory calculation augmented by a next-to-leading threshold logarithm resummation with a continuum relativistic fixed-order QCD NLO simulation.

  16. Top quark discovered

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Nine months after a careful announcement of tentative evidence for the long-awaited sixth 'top' quark, physicists from the CDF and DO experiments at Fermilab's Tevatron proton-antiproton collider declared on 2 March that they had finally discovered the top quark. Last year (June 1994, page 1), the CDF experiment at the Tevatron reported a dozen candidate top events. These, said CDF, had all the characteristics expected of top, but the difficulties of extracting the tiny signal from a trillion proton-antiproton collisions made them shy of claiming a discovery. For its part, the companion DO Tevatron experiment reported a few similar events but were even more guarded about their interpretation as top quarks. Just after these hesitant announcements, performance at the Tevatron improved dramatically last summer. After the commissioning of a new linear accelerator and a magnet realignment, the machine reached a new world record proton-antiproton collision luminosity of 1.28 x 10 31 per sq cm per s, ten times that originally planned. Data began to pour in at an unprecedented rate and the data sample grew to six trillion collisions. Luminosity has subsequently climbed to 1.7 x 10 31 . The top quark is the final letter in the alphabet of Standard Model particles. According to this picture, all matter is composed of six stronglyinteracting subnuclear particles, the quarks, and six weakly interacting particles, the leptons. Both sextets are neatly arranged as three pairs in order of increasing mass. The fifth quark, the 'beauty' or 'b' quark, was also discovered at Fermilab, back in 1977. Since then physicists have been eagerly waiting for the top to turn up, but have been frustrated by its heaviness - the top is some 40 times the mass of its 'beautiful' partner. Not only is the top quark the heaviest by far, but it is the only quark which has been actively hunted. After the quarry was glimpsed last year, the net has now been

  17. Audiitorite TOP 50 aastal 2005

    Index Scriptorium Estoniae

    2006-01-01

    Audiitorite TOP. Vt. samas: Käibe TOP 10; Käibe kasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; ROE TOP 10; Ketlin Priilinn. Kasvu tagavad lojaalsed kliendid; Klient on audiitori parim müügimees; Teeli Remmelg. Kliendid vaatavad pigem kvaliteeti kui madalat hinda. Kommenteerivad Signe Keernik ja Kalle Lahe. Tabel: Audiitoriettevõtete üld- ja finantsandmed

  18. Jõgevamaa ettevõtete TOP 55

    Index Scriptorium Estoniae

    2004-01-01

    Jõgevamaa ettevõtete TOP 55 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Jõgevamaa firmade üld- ja finantsandmed

  19. Põlvamaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2004-01-01

    Ettevõtete TOP 50. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Põlvamaa firmade üldandmed. Põlvamaa firmade finantsandmed

  20. Viljandimaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Viljandimaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Viljandimaa ettevõtete üld- ja finantsandmed

  1. Jõgevamaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Jõgevamaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Jõgevamaa ettevõtete üld- ja finantsandmed

  2. Boosted tops at ATLAS

    CERN Document Server

    Villaplana, M; The ATLAS collaboration

    2011-01-01

    A sample of candidate events for highly boosted top quarks is selected following the standard ATLAS selection for semi-leptonic ttbar events plus a requirement that the invariant mass of the reconstructed ttbar pair is greater than 700 GeV. Event displays are presented for the most promising candidates, as well as quantitative results for observables designed to isolate a boosted top quark signal.

  3. Telekommunikatsiooni & arvutitootjate TOP

    Index Scriptorium Estoniae

    2006-01-01

    Telekommunikatsiooni TOP 30. Tabelid. Vt. samas: Indrek Kald. Elisa ka tänavu esikohal; Väike Tele2 võidab paindlikkusest; Kernel läks üle piiri. Diagrammid. Arvutifirmade TOP 100. Tabelid. Vt. samas: Enn Heinsoo. Esikoha tõi kontori müük; Proeksperdil suund välisturgudele;¡ Ida-Eesti turg arenevale firmale kitsas. Diagrammid. Nimekiri: Omanikud

  4. H-mode pedestal and threshold studies over an expanded operating space on Alcator C-Moda)

    Science.gov (United States)

    Hubbard, A. E.; Hughes, J. W.; Bespamyatnov, I. O.; Biewer, T.; Cziegler, I.; LaBombard, B.; Lin, Y.; McDermott, R.; Rice, J. E.; Rowan, W. L.; Snipes, J. A.; Terry, J. L.; Wolfe, S. M.; Wukitch, S.

    2007-05-01

    This paper reports on studies of the edge transport barrier and transition threshold of the high confinement (H) mode of operation on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)], over a wide range of toroidal field (2.6-7.86T) and plasma current (0.4-1.7MA). The H-mode power threshold and edge temperature at the transition increase with field. Barrier widths, pressure limits, and confinement are nearly independent of field at constant current, but the operational space at high B shifts toward higher temperature and lower density and collisionality. Experiments with reversed field and current show that scrape-off-layer flows in the high-field side depend primarily on configuration. In configurations with the B ×∇B drift away from the active X-point, these flows lead to more countercurrent core rotation, which apparently contributes to higher H-mode thresholds. In the unfavorable case, edge temperature thresholds are higher, and slow evolution of profiles indicates a reduction in thermal transport prior to the transition in particle confinement. Pedestal temperatures in this case are also higher than in the favorable configuration. Both high-field and reversed-field results suggest that parameters at the L-H transition are influencing the evolution and parameters of the H-mode pedestal.

  5. Climatic impact of volcanic eruptions

    Science.gov (United States)

    Rampino, Michael R.

    1991-01-01

    Studies have attempted to 'isolate' the volcanic signal in noisy temperature data. This assumes that it is possible to isolate a distinct volcanic signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, volcanism) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the volcanic dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical volcanic aerosol clouds.

  6. Rate of volcanism on Venus

    International Nuclear Information System (INIS)

    Fegley, B. Jr.; Prinn, R.G.

    1988-07-01

    The maintenance of the global H 2 SO 4 clouds on Venus requires volcanism to replenish the atmospheric SO 2 which is continually being removed from the atmosphere by reaction with calcium minerals on the surface of Venus. The first laboratory measurements of the rate of one such reaction, between SO 2 and calcite (CaCO 3 ) to form anhydrite (CaSO 4 ), are reported. If the rate of this reaction is representative of the SO 2 reaction rate at the Venus surface, then we estimate that all SO 2 in the Venus atmosphere (and thus the H 2 SO 4 clouds) will be removed in 1.9 million years unless the lost SO 2 is replenished by volcanism. The required rate of volcanism ranges from about 0.4 to about 11 cu km of magma erupted per year, depending on the assumed sulfur content of the erupted material. If this material has the same composition as the Venus surface at the Venera 13, 14 and Vega 2 landing sites, then the required rate of volcanism is about 1 cu km per year. This independent geochemically estimated rate can be used to determine if either (or neither) of the two discordant (2 cu km/year vs. 200 to 300 cu km/year) geophysically estimated rates is correct. The geochemically estimated rate also suggests that Venus is less volcanically active than the Earth

  7. Volcanic eruptions and solar activity

    Science.gov (United States)

    Stothers, Richard B.

    1989-01-01

    The historical record of large volcanic eruptions from 1500 to 1980 is subjected to detailed time series analysis. In two weak but probably statistically significant periodicities of about 11 and 80 yr, the frequency of volcanic eruptions increases (decreases) slightly around the times of solar minimum (maximum). Time series analysis of the volcanogenic acidities in a deep ice core from Greenland reveals several very long periods ranging from about 80 to about 350 yr which are similar to the very slow solar cycles previously detected in auroral and C-14 records. Solar flares may cause changes in atmospheric circulation patterns that abruptly alter the earth's spin. The resulting jolt probably triggers small earthquakes which affect volcanism.

  8. The Lathrop Wells volcanic center

    International Nuclear Information System (INIS)

    Crowe, B.; Morley, R.

    1992-01-01

    The Lathrop Wells volcanic center is located 20 km south of the potential Yucca Mountain site, at the south end of the Yucca Mountain range. This paper discusses a detailed Study Plan which was prepared describing planned geochronology and field studies to assess the chronology of the Lathrop Wells volcanic center and other Quaternary volcanic centers in the region. A paper was published discussing the geomorphic and soil evidence for a late Pleistocene or Holoceno age for the main cone of the center. The purpose of this paper was to expose the ideas concerning the age of the Lathrop Wells center to scientific scrutiny. Additionally, field evidence was described suggesting the Lathrop Wells center may have formed from multiple eruptive events with significant intervals of no activity between events. This interpretation breaks with established convention in the volcanological literature that small volume basalt centers are monogenetic

  9. TOP2017 Experimental summary

    CERN Document Server

    Giammanco, Andrea

    2017-01-01

    Thanks to the unprecedentedly fast accumulation of high-energy data at the LHC during the ongoing Run~2, most of the traditional top-quark analyses are experiencing the luxury of having to worry about how to punch through the ``Systematics Wall'', and think about new ways to maximize the utility of their data. New processes involving top quarks are being studied for the first time, and the good old pair-production processes are being explored in unusual settings, such as collisions involving heavy ions, or ``reference data'' collected by the LHC at relatively low centre-of-mass energy. The TOP2017 conference featured 37 talks delivered by experimental physicists, including seven in the ``Young Scientists Forum'' where young colleagues were given the opportunity to elaborate more deeply than usual on their own work. As it is impossible to do justice to all the experimental resu...

  10. Top-ophilia

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris; /Fermilab

    2008-01-01

    Almost from the moment in June 1977 when the discovery of the Upsilon resonance revealed the existence of what we now call the bottom quark, physicists began searching for its partner. Through the years, as we established the electric charge and weak isospin of the b-quark, and detected the virtual influence of its mate, it became clear that the top quark must exist. Exactly at what mass, we couldn't say, but we knew just how top events would look. We also knew that top events would be rare--if the Tevatron could make them at all--and that picking out the events would pose a real challenge for the experimenters and their detectors.

  11. Recurrence models of volcanic events: Applications to volcanic risk assessment

    International Nuclear Information System (INIS)

    Crowe, B.M.; Picard, R.; Valentine, G.; Perry, F.V.

    1992-01-01

    An assessment of the risk of future volcanism has been conducted for isolation of high-level radioactive waste at the potential Yucca Mountain site in southern Nevada. Risk used in this context refers to a combined assessment of the probability and consequences of future volcanic activity. Past studies established bounds on the probability of magmatic disruption of a repository. These bounds were revised as additional data were gathered from site characterization studies. The probability of direct intersection of a potential repository located in an eight km 2 area of Yucca Mountain by ascending basalt magma was bounded by the range of 10 -8 to 10 -10 yr -1 2 . The consequences of magmatic disruption of a repository were estimated in previous studies to be limited. The exact releases from such an event are dependent on the strike of an intruding basalt dike relative to the repository geometry, the timing of the basaltic event relative to the age of the radioactive waste and the mechanisms of release and dispersal of the waste radionuclides in the accessible environment. The combined low probability of repository disruption and the limited releases associated with this event established the basis for the judgement that the risk of future volcanism was relatively low. It was reasoned that that risk of future volcanism was not likely to result in disqualification of the potential Yucca Mountain site

  12. TOP LINAC design

    International Nuclear Information System (INIS)

    Picardi, L.; Ronsivalle, C.; Vignati, A.

    1997-11-01

    The report describes a linear accelerator for protons named TOP LINAC designed for the TOP (Terapia Oncologica con Protoni, Oncological Protontherapy) project launched by the Italian National Institute of Health (Istituto Superiore di Sanita', ISS) to explore in collaboration with the biggest Oncological Hospital in Rome (Istituto Regina Elena, IRE) the potentialities of the therapy with accelerated protons and establish guide lines for the application of this new type of radiotherapy in comparison with the more traditional electron and x-rays radiotherapy. The concept of a compact accelerator for protontherapy applications bore within the Italian Hadrontherapy Collaboration (TERA Collaboration) with the aim to diffuse the protontherapy on the National territory. The ISS program plans to use the TOP linac proton beam also for production of PET (Positron Emission Tomography) radioisotopes and radiobiology studies. Official agreements are in course between ISS and ENEA which provides its experience in the industrial and medical accelerators for the design and the construction of the TOP linac. The accelerator that will be the first 3 GHz proton linac in the world, will be composed of a 428.3 MHz 7 Me V RFQ + DTL injector followed by a 7-65 Me V section of a 3 GHz SCDTL structure and a 65 - 200 Me V variable energy SCL 3 GHz structure. In particular the SCDTL section uses a highly innovative accelerating structure patented by ENEA. In this report the clinical and physical requests are discussed and a preliminary design of the whole machine is given

  13. Top emitting white OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Freitag, Patricia; Luessem, Bjoern; Leo, Karl [Technische Universitaet Dresden, Institut fuer Angewandte Photophysik, George-Baehr-Strasse 1, 01069 Dresden (Germany)

    2009-07-01

    Top emitting organic light emitting diodes (TOLEDs) provide a number of interesting opportunities for new applications, such as the opportunity to fabricate ITO-free devices by using opaque substrates. This makes it possible to manufacture low cost OLEDs for signage and lighting applications. A general top emitting device consists of highly reflecting metal contacts as anode and semitransparent cathode, the latter one for better outcouling reasons. In between several organic materials are deposited as charge transporting, blocking, and emission layers. Here, we show a top emitting white organic light emitting diode with silver electrodes arranged in a p-i-n structure with p- and n-doped charge transport layers. The centrical emission layer consists of two phosphorescent (red and green) and one fluorescent (blue) emitter systems separated by an ambipolar interlayer to avoid mutual exciton quenching. By adding an additional dielectric capping layer on top of the device stack, we achieve a reduction of the strong microcavity effects which appear due to the high reflection of both metal electrodes. Therefore, the outcoupled light shows broad and nearly angle-independent emission spectra, which is essential for white light emitting diodes.

  14. Top quark theory

    Indian Academy of Sciences (India)

    2012-10-04

    Oct 4, 2012 ... The theoretical aspects of a number of top quark properties such as ... to the quadratic divergences of the Higgs self-energy, while yet, ..... given in the literature, each with the aim of recovering a well-behaved expansion in αs.

  15. Top quark properties

    Indian Academy of Sciences (India)

    eter for the tests of the electroweak theory, since radiative corrections to many ... The uncertainty due to jet energy scale (JES) is the dominating systematic .... In the Standard Model, the charge of the top quark is predicted to be that of a normal up- ..... non-negative and f+ + f0 < 1, and the star marks the expectation from the ...

  16. Anomalous top magnetic couplings

    Indian Academy of Sciences (India)

    2012-11-09

    Nov 9, 2012 ... Corresponding author. E-mail: remartinezm@unal.edu.co. Abstract. The real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the tbW vertex in the Standard Model (SM) are computed. Keywords. Top; anomalous. PACS Nos 14.65.Ha; 12.15 ...

  17. Candidate constructional volcanic edifices on Mercury

    OpenAIRE

    Wright, J.; Rothery, D. A.; Balme, M. R.; Conway, S. J.

    2018-01-01

    [Introduction] Studies using MESSENGER data suggest that Mercury’s crust is predominantly a product of effusive volcanism that occurred in the first billion years following the planet’s formation. Despite this planet-wide effusive volcanism, no constructional volcanic edifices, characterized by a topographic rise, have hitherto been robustly identified on Mercury, whereas constructional volcanoes are common on other planetary bodies in the solar system with volcanic histories. Here, we descri...

  18. High resolution main-ion charge exchange spectroscopy in the DIII-D H-mode pedestal.

    Science.gov (United States)

    Grierson, B A; Burrell, K H; Chrystal, C; Groebner, R J; Haskey, S R; Kaplan, D H

    2016-11-01

    A new high spatial resolution main-ion (deuterium) charge-exchange spectroscopy system covering the tokamak boundary region has been installed on the DIII-D tokamak. Sixteen new edge main-ion charge-exchange recombination sightlines have been combined with nineteen impurity sightlines in a tangentially viewing geometry on the DIII-D midplane with an interleaving design that achieves 8 mm inter-channel radial resolution for detailed profiles of main-ion temperature, velocity, charge-exchange emission, and neutral beam emission. At the plasma boundary, we find a strong enhancement of the main-ion toroidal velocity that exceeds the impurity velocity by a factor of two. The unique combination of experimentally measured main-ion and impurity profiles provides a powerful quasi-neutrality constraint for reconstruction of tokamak H-mode pedestals.

  19. Scaling of ELM and H-mode pedestal characteristics in ITER shape discharges in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Osborne, T.H.; Groebner, R.J.; Lao, L.L.; Leonard, A.W.; Miller, R.L.; Thomas, D.M.; Waltz, R.E.; Maingi, R.; Porter, G.D.

    1997-07-01

    The authors have shown a correlation between the H-mode pressure pedestal height and the energy confinement enhancement in ITER shape discharges on DIII-D which is consistent with the behavior of H in different ELM classes. The width of the steep gradient region was found to equally well fit the scalings δ/R ∝ (ρ POL /R) 2/3 and δ/R ∝ (β POL PED /R) 1/2 . The normalized pressure gradient α MHD was found to be relatively constant just before a type I ELM. An estimate of T PED for ITER gave 1 to 5 keV. They also estimate ΔE ELM ≅ 26 MJ for ITER. They identified a distinct class of type III ELM at low density which may play a role in setting H at powers near the H-mode threshold power

  20. Estimation of Kubo number and correlation length of fluctuating magnetic fields and pressure in BOUT + + edge pedestal collapse simulation

    Science.gov (United States)

    Kim, Jaewook; Lee, W.-J.; Jhang, Hogun; Kaang, H. H.; Ghim, Y.-C.

    2017-10-01

    Stochastic magnetic fields are thought to be as one of the possible mechanisms for anomalous transport of density, momentum and heat across the magnetic field lines. Kubo number and Chirikov parameter are quantifications of the stochasticity, and previous studies show that perpendicular transport strongly depends on the magnetic Kubo number (MKN). If MKN is smaller than one, diffusion process will follow Rechester-Rosenbluth model; whereas if it is larger than one, percolation theory dominates the diffusion process. Thus, estimation of Kubo number plays an important role to understand diffusion process caused by stochastic magnetic fields. However, spatially localized experimental measurement of fluctuating magnetic fields in a tokamak is difficult, and we attempt to estimate MKNs using BOUT + + simulation data with pedestal collapse. In addition, we calculate correlation length of fluctuating pressures and Chirikov parameters to investigate variation correlation lengths in the simulation. We, then, discuss how one may experimentally estimate MKNs.

  1. CPT analysis with top physics

    Energy Technology Data Exchange (ETDEWEB)

    Cembranos, Jose A. R., E-mail: cembra@fis.ucm.es [Universidad Complutense de Madrid, Departamento de Fisica Teorica I (Spain)

    2013-03-15

    We discuss the possibility of observing CPT violation from top anti-top production in hadronic colliders. We study a general approach by analyzing constraints on the mass difference between the top and anti-top quarks. We present current bounds from Tevatron data, and comment on the prospects for improving these bounds at the LHC and the ILC.

  2. Top Quark Properties at Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Lysák, Roman [Prague, Inst. Phys.

    2017-11-27

    The latest CDF and D0 experiment measurements of the top quark properties except the top quark mass are presented. The final combination of the CDF and D0 forward-backward asymmetry measurements is shown together with the D0 measurements of the inclusive top quark pair cross-section as well as the top quark polarization.

  3. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1979-01-01

    Three basic topics are addressed for the disruptive event analysis: first, the range of disruptive consequences of a radioactive waste repository by volcanic activity; second, the possible reduction of the risk of disruption by volcanic activity through selective siting of a repository; and third, the quantification of the probability of repository disruption by volcanic activity

  4. Landfill Top Covers

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Kjeldsen, Peter

    2011-01-01

    The purpose of the final cover of a landfill is to contain the waste and to provide for a physical separation between the waste and the environment for protection of public health. Most landfill covers are designed with the primary goal to reduce or prevent infiltration of precipitation...... into the landfill in order to minimize leachate generation. In addition the cover also has to control the release of gases produced in the landfill so the gas can be ventilated, collected and utilized, or oxidized in situ. The landfill cover should also minimize erosion and support vegetation. Finally the cover...... is landscaped in order to fit into the surrounding area/environment or meet specific plans for the final use of the landfill. To fulfill the above listed requirements landfill covers are often multicomponent systems which are placed directly on top of the waste. The top cover may be placed immediately after...

  5. Computing Z-top

    International Nuclear Information System (INIS)

    Kashani-Poor, A.K.

    2014-01-01

    The topological string presents an arena in which many features of string theory proper, such as the interplay between world-sheet and target space descriptions or open-closed duality, can be distilled into computational techniques which yield results beyond perturbation theory. In this thesis, I will summarize my research activity in this area. The presentation is organized around computations of the topological string partition function Z-top based on various perspectives on the topological string. (author)

  6. Top of the list

    International Nuclear Information System (INIS)

    Cameron, A.; Vries, E. de

    2006-01-01

    In this article the authors look at how the major turbine suppliers fared in the year 2005, and look forward to 2006 which could be the best ever for the wind industry. The world wind turbine market continues to be dominated by ten major companies, who together account for almost 100% of the total global market. Although there are some new companies on the horizon it is the ten major companies that the authors concentrate on, in particular the top three, Vestas, Gamesa and Enercon who between them control 66% of the market. They give their overall report on business in 2005 and give their predictions for 2006. By far the leading wind turbine supplier is the Danish Company Vestas, accounting for over 30% of the global market. However all of the top ten companies report a successful year and all are expecting an even better 2006. This paper also reports on potential newcomers to the industry, one of these is California-based Clipper Windpower which commenced manufacturing the 2.5 MW Liberty turbine in Iowa. Chinese manufacturer Goldwind is also looking to enter the market having acquired a licence to produce the Vensys 1.2 MW turbine. It may well be that changes are on the way, there will be jockeying for position at the top and newcomers will want to make an impression on the market

  7. Top quark measurements at ATLAS

    CERN Document Server

    Grancagnolo, Sergio; The ATLAS collaboration

    2017-01-01

    The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections including differential distributions will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass and searches for rare top quark decays are also presented.

  8. Top quark measurements at ATLAS

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00041686; The ATLAS collaboration

    2017-01-01

    The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it allows us to probe the properties of bare quarks at the Large Hadron Collider. Highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data will be presented: top-quark pair and single top production cross sections including differential distributions will be presented alongside measurements of top-quark properties, including results using boosted top quarks, probe our understanding of top-quark production in the TeV regime. Measurements of the top-quark mass and searches for rare top quark decays are also presented.

  9. Petrography of the Paleogene Volcanic Rocks of the Sierra Maestra, Southeastern Cuba

    Science.gov (United States)

    Bemis, V. L.

    2006-12-01

    This study is a petrographic analysis of over 200 specimens of the Paleogene volcanic rocks of the Sierra Maestra (Southerneastern Cuba), a key structure in the framework of the northern Caribbean plate boundary evolution. The purpose of this study is to understand the eruptive processes and the depositional environments. The volcanic sequence in the lower part of the Sierra Maestra begins with highly porphyritic pillow lavas, topped by massive tuffs and autoclastic flows. The presence of broken phenocrystals, palagonitic glass and hyaloclastites in this section of the sequence suggests that the prevalent mode of eruption was explosive. The absence of welding in the tuffs suggests that the rocks were emplaced in a deep submarine environment. Coherent flows, much less common than the massive tuffs, show evidence of autoclastic fracturing, also indicating low temperature-submarine environments. These observations support the hypothesis that the Sierra Maestra sequence may be neither part of the Great Antilles Arc of the Mesozoic nor any other fully developed volcanic arc, rather a 250 km long, submarine eruptive system of dikes, flows and sills, most likely a back-arc structure. The volcanic rocks of the upper sequence are all very fine grained, reworked volcaniclastic materials, often with the structures of distal turbidities, in mode and texture similar to those drilled on the Cayman Rise. This study suggests that the Sierra Maestra most likely records volcanism of diverse sources: a local older submarine source, and one or more distal younger sources, identifiable with the pan-Caribbean volcanic events of the Tertiary.

  10. Chronology and References of Volcanic Eruptions and Selected Unrest in the United States, 1980-2008

    Science.gov (United States)

    Diefenbach, Angela K.; Guffanti, Marianne; Ewert, John W.

    2009-01-01

    The United States ranks as one of the top countries in the world in the number of young, active volcanoes within its borders. The United States, including the Commonwealth of the Northern Mariana Islands, is home to approximately 170 geologically active (age activity, unrest, that do not culminate in eruptions. Monitoring volcanic activity in the United States is the responsibility of the U.S. Geological Survey (USGS) Volcano Hazards Program (VHP) and is accomplished with academic, Federal, and State partners. The VHP supports five Volcano Observatories - the Alaska Volcano Observatory (AVO), Cascades Volcano Observatory (CVO), Yellowstone Volcano Observatory (YVO), Long Valley Observatory (LVO), and Hawaiian Volcano Observatory (HVO). With the exception of HVO, which was established in 1912, the U.S. Volcano Observatories have been established in the past 27 years in response to specific volcanic eruptions or sustained levels of unrest. As understanding of volcanic activity and hazards has grown over the years, so have the extent and types of monitoring networks and techniques available to detect early signs of anomalous volcanic behavior. This increased capability is providing us with a more accurate gauge of volcanic activity in the United States. The purpose of this report is to (1) document the range of volcanic activity that U.S. Volcano Observatories have dealt with, beginning with the 1980 eruption of Mount St. Helens, (2) describe some overall characteristics of the activity, and (3) serve as a quick reference to pertinent published literature on the eruptions and unrest documented in this report.

  11. Naisjuhtidega ettevõtete TOP 100

    Index Scriptorium Estoniae

    2004-01-01

    Naisjuhtidega ettevõtete TOP 100. Käibe TOP 20. Käibe kasvu TOP 20. Kasumi TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP 25. Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP 25. Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP 25. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide palga TOP 25

  12. Development of a risk assessment tool for volcanic urban environments: RiskScape and the Auckland Volcanic Field, New Zealand

    Science.gov (United States)

    Deligne, N. I.; Leonard, G.; King, A.; Wilson, G.; Wilson, T.; Lindsay, J. M.

    2013-12-01

    Auckland city, home to a third of New Zealand's population, is situated on top of the Auckland Volcanic Field (AVF), which last erupted roughly 500 years ago. Since 2008, the Determining Volcanic Risk in Auckland (DEVORA) program has investigated the geologic context of the AVF, improved timing constraints of past eruptions, explored possible tempo-spatial-volume eruption trends, and identified likely styles and hazards of future eruptions. DEVORA is now moving into development of risk and societal models for Auckland. The volcanic module of RiskScape, a multi-hazard risk assessment tool developed by Crown Research Institutes GNS Science and NIWA, will be expanded and used to model risk and impact to the built environment and population caused by a future AVF eruption. RiskScape models casualties, damage and disruption caused by various hazards, the resulting reduced functionality of assets, and associated clean up costs. A strength of RiskScape is that the effect of various mitigation strategies can be explored by strengthening asset attributes and examining resulting changes in the output risk evaluation. We present our framework for building a volcano hazard exposure module for RiskScape along with our approach for assessing asset vulnerability through the development of fragility functions. We also present the framework for engagement with regional Auckland stakeholders, including representatives of local and regional governments and utility companies, to identify complementary needs to ensure that final risk products are relevant and useable by end users.

  13. Holocene volcanic geology, volcanic hazard, and risk on Taveuni, Fiji

    International Nuclear Information System (INIS)

    Cronin, S.J.; Neall, V.E.

    2001-01-01

    The Holocene volcanic geology of Taveuni has been mapped in order to produce a volcanic hazard and risk assessment for the island. Taveuni is the third-largest island of the Fiji group and home to 14,500 people. At least cubic km 2.7 of olivine-alkali-basalt magma was erupted from over 100 events throughout the Holocene. Vents are concentrated along a northeast-striking rift zone that is parallel to other regional structural trends. There is an overall trend of younging southward along the rift. Holocene lavas and tephras are grouped within six newly defined eruptive periods, established on a basis of radiocarbon dating. Within these periods, 14 tephra layers, useful as local marker horizons, are recognised. At least 58% of Holocene eruptions produced lava flows, while almost all produced some tephra. Individual eruption event volumes ranged between 0.001 and cubic km 0.20 (dense rock equivalent). Many eruptions involved at least some phases of phreatic and/or phreato-magmatic activity, although dominant hydrovolcanic activity was limited to only a few events. A volcanic hazard map is presented, based on the Holocene geology map and statistical analyses of eruption recurrence. The highest levels of ground-based and near-vent hazards are concentrated along the southern portion of the island's rift axis, with the paths of initial lava flows predicted from present topography. Tephra fall hazards are based on eruption parameters interpreted from mapped Holocene tephra layers. Hawaiian explosive-style eruptions appear to be a dominant eruptive process, with prevailing low-level (<3 km) southeasterly winds dispersing most tephra to the northwestern quadrant. Vulnerable elements (population centres, infrastructure, and economy) on Taveuni have been considered in deriving a volcanic risk assessment for the island. A number of infrastructural and subdivision developments are either under way or planned for the island, driven by its highly fertile soils and availability of

  14. Study of top and anti-top mass difference

    CERN Document Server

    Leedumrongwatthanakun, Saroch

    2013-01-01

    The invariance of the standard model under CPT transformations leads to the equality of particle and antiparticle masses. The recent measurements performed by the CMS experiment on the top anti-top mass difference are a test of such symmetry. In this work non-perturbative QCD effects, which may eventually lead to an apparent difference in the mass of a top and anti-top quark, are studied.

  15. Can rain cause volcanic eruptions?

    Science.gov (United States)

    Mastin, Larry G.

    1993-01-01

    Volcanic eruptions are renowned for their violence and destructive power. This power comes ultimately from the heat and pressure of molten rock and its contained gases. Therefore we rarely consider the possibility that meteoric phenomena, like rainfall, could promote or inhibit their occurrence. Yet from time to time observers have suggested that weather may affect volcanic activity. In the late 1800's, for example, one of the first geologists to visit the island of Hawaii, J.D. Dana, speculated that rainfall influenced the occurrence of eruptions there. In the early 1900's, volcanologists suggested that some eruptions from Mount Lassen, Calif., were caused by the infiltration of snowmelt into the volcano's hot summit. Most such associations have not been provable because of lack of information; others have been dismissed after careful evaluation of the evidence.

  16. Source mechanisms of volcanic tsunamis.

    Science.gov (United States)

    Paris, Raphaël

    2015-10-28

    Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness. © 2015 The Author(s).

  17. Volcanic hazards in Central America

    Science.gov (United States)

    Rose, William I.; Bluth, Gregg J.S.; Carr, Michael J.; Ewert, John W.; Patino, Lina C.; Vallance, James W.

    2006-01-01

    This volume is a sampling of current scientific work about volcanoes in Central America with specific application to hazards. The papers reflect a variety of international and interdisciplinary collaborations and employ new methods. The book will be of interest to a broad cross section of scientists, especially volcanologists. The volume also will interest students who aspire to work in the field of volcano hazards mitigation or who may want to work in one of Earth’s most volcanically active areas.

  18. Tekstiilitööstuse TOP 47

    Index Scriptorium Estoniae

    2005-01-01

    Tekstiilitööstuse TOP 47; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Varade tootlikkuse TOP 20; Tekstiilitööstuse TOP-i firmade üld- ja finantsandmed

  19. Rõivatööstuse TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Rõivatööstuse TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Rõivatööstuse TOP-i firmade üld- ja finantsandmed

  20. Eesti Ettevõtete TOP 100

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Käibe TOP 500. Käibe kasvu TOP 100. Kasumi TOP 100. Kasumi kasvu TOP 100. Rentaabluse TOP 100. Omakapitali tootlikkuse TOP 100. Eesti edukamate ettevõtete üldandmed. Eesti edukamate ettevõtete finantsnäitajad. Valdkonna ja maakonna TOP-ide edukamate ettevõtete finantsnäitajad

  1. Characterizing Volcanic Eruptions on Venus: Some Realistic (?) Scenarios

    Science.gov (United States)

    Stofan, E. R.; Glaze, L. S.; Grinspoon, D. H.

    2011-01-01

    When Pioneer Venus arrived at Venus in 1978, it detected anomalously high concentrations of SO2 at the top of the troposphere, which subsequently declined over the next five years. This decline in SO2 was linked to some sort of dynamic process, possibly a volcanic eruption. Observations of SO2 variability have persisted since Pioneer Venus. More recently, scientists from the Venus Express mission announced that the SPICAV (Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus) instrument had measured varying amounts of SO2 in the upper atmosphere; VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) measured no similar variations in the lower atmosphere (ESA, 4 April, 2008). In addition, Fegley and Prinn stated that venusian volcanoes must replenish SO2 to the atmosphere, or it would react with calcite and disappear within 1.9 my. Fegley and Tremain suggested an eruption rate on the order of approx 1 cubic km/year to maintain atmospheric SO2; Bullock and Grinspoon posit that volcanism must have occurred within the last 20-50 my to maintain the sulfuric acid/water clouds on Venus. The abundance of volcanic deposits on Venus and the likely thermal history of the planet suggest that it is still geologically active, although at rates lower than Earth. Current estimates of resurfacing rates range from approx 0.01 cubic km/yr to approx 2 cubic km/yr. Demonstrating definitively that Venus is still volcanically active, and at what rate, would help to constrain models of evolution of the surface and interior, and help to focus future exploration of Venus.

  2. Volcanic deformation in the Andes

    Science.gov (United States)

    Riddick, S.; Fournier, T.; Pritchard, M.

    2009-05-01

    We present the results from an InSAR survey of volcanic activity in South America. We use data from the Japanese Space Agency's ALOS L-band radar satellite from 2006-2009. The L-band instrument provides better coherence in densely vegetated regions, compared to the shorter wave length C-band data. The survey reveals volcano related deformation in regions, north, central and southern, of the Andes volcanic arc. Since observations are limited to the austral summer, comprehensive coverage of all volcanoes is not possible. Yet, our combined observations reveal volcanic/hydrothermal deformation at Lonquimay, Llaima, Laguna del Maule, and Chaitén volcanoes, extend deformation measurements at Copahue, and illustrate temporal complexity to the previously described deformation at Cerro Hudson and Cordón Caulle. No precursory deformation is apparent before the large Chaitén eruption (VEI_5) of 2 May 2008, (at least before 16 April) suggesting rapid magma movement from depth at this long dormant volcano. Subsidence at Ticsani Volcano occurred coincident with an earthquake swarm in the same region.

  3. Volcanic mercury in Pinus canariensis

    Science.gov (United States)

    Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

    2013-08-01

    Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg-1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg-1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg-1) and bark (6.0 μg kg-1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

  4. Source mechanism of volcanic tremor

    Energy Technology Data Exchange (ETDEWEB)

    Ferrick, M.G.; Qamar, A.; St. Lawrence, W.F.

    1982-10-10

    Low-frequency (<10 Hz) volcanic earthquakes originate at a wide range of depths and occur before, during, and after magmatic eruptions. The characteristics of these earthquakes suggest that they are not typical tectonic events. Physically analogous processes occur in hydraulic fracturing of rock formations, low-frequency icequakes in temperate glaciers, and autoresonance in hydroelectric power stations. We propose that unsteady fluid flow in volcanic conduits is the common source mechanism of low-frequency volcanic earthquakes (tremor). The fluid dynamic source mechanism explains low-frequency earthquakes of arbitrary duration, magnitude, and depth of origin, as unsteady flow is independent of physical properties of the fluid and conduit. Fluid transients occur in both low-viscosity gases and high-viscosity liquids. A fluid transient analysis can be formulated as generally as is warranted by knowledge of the composition and physical properties of the fluid, material properties, geometry and roughness of the conduit, and boundary conditions. To demonstrate the analytical potential of the fluid dynamic theory, we consider a single-phase fluid, a melt of Mount Hood andesite at 1250/sup 0/C, in which significant pressure and velocity variations occur only in the longitudinal direction. Further simplification of the conservation of mass and momentum equations presents an eigenvalue problem that is solved to determine the natural frequencies and associated damping of flow and pressure oscillations.

  5. Volcanic mercury in Pinus canariensis.

    Science.gov (United States)

    Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

    2013-08-01

    Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg(-1)) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg(-1)). Thus, mercury emissions originating from the eruption remained only as a mark-in pyroclastic wounds-and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg(-1)) and bark (6.0 μg kg(-1)) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

  6. Treasury Offset Program (TOP) MI

    Data.gov (United States)

    Social Security Administration — The TOP MI helps OPSOS coordinate TOP case processing in the regions. The MI also helped communicate our progress and findings to BFQM and ORDP, as well as the ACOSS.

  7. Top Quark Physics with CMS

    CERN Multimedia

    CERN. Geneva

    2011-01-01

    Higgs mechanism. There are various hints at deviations from the Standard Model expectation which have been observed recently by Tevatron experiments in top final states. Several signatures of new physics accessible at the LHC either suffer from top-quark production as a significant background or contain top quarks themselves. In this talk, we present results on top quark physics obtained from the first LHC data collected by the CMS experiment.They include measurements of the top pair production cross section in various channels and their combination, measurements of the top quark mass, the single top cross section, a search for new particles decaying into top pairs, and a first look at the charge asymmetry.

  8. Disruptive event analysis: volcanism and igneous intrusion

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1980-08-01

    An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity

  9. Single-crystal SrTiO3 fiber grown by laser heated pedestal growth method: influence of ceramic feed rod preparation in fiber quality

    Directory of Open Access Journals (Sweden)

    D. Reyes Ardila

    1998-10-01

    Full Text Available The rapidly spreading use of optical fiber as a transmission medium has created an interest in fiber-compatible optical devices and methods for growing them, such as the Laser Heated Pedestal Growth (LHPG. This paper reports on the influence of the ceramic feed rod treatment on fiber quality and optimization of ceramic pedestal processing that allows improvements to be made on the final quality in a simple manner. Using the LHPG technique, transparent crack-free colorless single crystal fibers of SrTiO3 (0.50 mm in diameter and 30-40 mm in length were grown directly from green-body feed rods, without using external oxygen atmosphere.

  10. Top production at hadron colliders

    Indian Academy of Sciences (India)

    New results on top quark production are presented from four hadron collider experiments: CDF and D0 at the Tevatron, and ATLAS and CMS at the LHC. Cross-sections for single top and top pair production are discussed, as well as results on the top–antitop production asymmetry and searches for new physics including ...

  11. Single top t-channel

    CERN Document Server

    Faltermann, Nils

    2017-01-01

    The production of single top quarks allows to study the interplay of top quark physics and the electroweak sector of the standard model. Deviations from predictions can be a hint for physics beyond the standard model. The t-channel is the dominant production mode for single top quarks at the LHC. This talk presents the latest measurements from the ATLAS and CMS collaborations.

  12. Forward Top Physics at LHCb

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    The first Run 2 measurement of top pair production in the dilepton channel at 13 TeV will be presented, along with previous Run 1 measurements in final states accessible to both single top and top pair production. Heavy flavour tagging strategies at LHCb will also be discussed.

  13. Interpretation of changes in diffusive and non-diffusive transport in the edge plasma during pedestal buildup following a low-high transition in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Stacey, W. M.; Sayer, M.-H.; Floyd, J.-P. [Georgia Tech, Atlanta, Georgia 30332 (United States); Groebner, R. J. [General Atomics, San Diego, California 92186 (United States)

    2013-01-15

    The evolution of diffusive and non-diffusive transport during pedestal buildup following a low-high (L-H) transition has been interpreted from a particle-momentum-energy balance analysis of the measured density, temperature, and rotation velocity profiles in the plasma edge (0.82<{rho}<1.0) of a DIII-D [Luxon, Nucl. Fusion 42, 614 (2002)] discharge. In the discharge examined, there was an edge-localized-mode-free period of more than 600 ms following the L-H transition, and the majority of edge pedestal development occurred within the first 100 ms following the L-H transition. There appears to be a spatio-temporal correlation among the measured toroidal and poloidal rotation, the formation of a negative well in the measured radial electric field, the creation of a large inward particle pinch, the calculated intrinsic rotation due to ion orbit loss, and the measured formation of steep gradients in density and temperature in the outer region ({rho}>0.95) of the edge pedestal.

  14. The top ten.

    Science.gov (United States)

    Davis, C

    1985-10-01

    3 lists were compiled to answer the question of what countries have experienced the most population growth from World War II to the present. The 1st list includes the 10 countries which accounted for the largest gain in world population. The 2nd list shows the 10 countries with the highest growth rates of the 150 or so most populous countries in the world. The last list also shows countries ranked by growth rate but is limited to those with a current population of at least 10 million. To deal with the fact that some countries did not exist at 1 of the reference points, a set of estimates for 1940 provided a convenient starting point. China and India headed the list of countries ranked by absolute gains. They contributed half again as much growth as the next 8 nations combined. Altogether Asia, home to almost 60% of the world's population, captured 5 of the top 10 slots. The US and the USSR are the only developed countries on the list. The Soviet Union also presents the 1st case on the list of a country with a lower ranking in population gain (6th) than in absolute size in 1985 (3rd). Many of the population giants of 1940 (Japan, Great Britain, Germany, France, and Italy) are not on the list. Despite large base populations, their growth has been slow in the intervening years. All of the countries with the highest growth rates experienced over 3% annual average growth during the last 45 years: Kuwait, United Arab Emirates, Libya, Venezuela, Costa Rica, Kenya, Ivory Coast, Mexico, Honduras, and Syria. The influence of immigration is much in evidence in this list and explains otherwise unachievable rates of growth. The top 4 countries in annual rates of growth are all oil exporters. The top 3 countries in the 3rd list -- Venezuela, Kenya, and Mexico -- are carried over from the 2nd list, sharing the characteristics of rapid population growth and substantial base populations. The geographic mix of this list is notable. Asia, Africa, and Latin America each have at least

  15. Improving volcanic ash predictions with the HYSPLIT dispersion model by assimilating MODIS satellite retrievals

    Science.gov (United States)

    Chai, Tianfeng; Crawford, Alice; Stunder, Barbara; Pavolonis, Michael J.; Draxler, Roland; Stein, Ariel

    2017-02-01

    Currently, the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) runs the HYSPLIT dispersion model with a unit mass release rate to predict the transport and dispersion of volcanic ash. The model predictions provide information for the Volcanic Ash Advisory Centers (VAAC) to issue advisories to meteorological watch offices, area control centers, flight information centers, and others. This research aims to provide quantitative forecasts of ash distributions generated by objectively and optimally estimating the volcanic ash source strengths, vertical distribution, and temporal variations using an observation-modeling inversion technique. In this top-down approach, a cost functional is defined to quantify the differences between the model predictions and the satellite measurements of column-integrated ash concentrations weighted by the model and observation uncertainties. Minimizing this cost functional by adjusting the sources provides the volcanic ash emission estimates. As an example, MODIS (Moderate Resolution Imaging Spectroradiometer) satellite retrievals of the 2008 Kasatochi volcanic ash clouds are used to test the HYSPLIT volcanic ash inverse system. Because the satellite retrievals include the ash cloud top height but not the bottom height, there are different model diagnostic choices for comparing the model results with the observed mass loadings. Three options are presented and tested. Although the emission estimates vary significantly with different options, the subsequent model predictions with the different release estimates all show decent skill when evaluated against the unassimilated satellite observations at later times. Among the three options, integrating over three model layers yields slightly better results than integrating from the surface up to the observed volcanic ash cloud top or using a single model layer. Inverse tests also show that including the ash-free region to constrain the model is not

  16. Top quark physics

    International Nuclear Information System (INIS)

    Menzione, A.

    1995-10-01

    Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t bar t decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity

  17. Top quark pair production and top quark properties at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Chang-Seong [INFN, Pisa

    2016-06-02

    We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $|V_{tb}|$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($A_{FB}$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $t\\bar t$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.

  18. Effects of a sheared toroidal rotation on the stability boundary of the MHD modes in the tokamak edge pedestal

    International Nuclear Information System (INIS)

    Aiba, N.; Tokuda, S.; Oyama, N.; Ozeki, T.; Furukawa, M.

    2009-01-01

    Effects of a sheared toroidal rotation are investigated numerically on the stability of the MHD modes in the tokamak edge pedestal, which relate to the type-I edge-localized mode. A linear MHD stability code MINERVA is newly developed for solving the Frieman-Rotenberg equation that is the linear ideal MHD equation with flow. Numerical stability analyses with this code reveal that the sheared toroidal rotation destabilizes edge localized MHD modes for rotation frequencies which are experimentally achievable, though the ballooning mode stability changes little by rotation. This rotation effect on the edge MHD stability becomes stronger as the toroidal mode number of the unstable MHD mode increases when the stability analysis was performed for MHD modes with toroidal mode numbers smaller than 40. The toroidal mode number of the unstable MHD mode depends on the stabilization of the current-driven mode and the ballooning mode by increasing the safety factor. This dependence of the toroidal mode number of the unstable mode on the safety factor is considered to be the reason that the destabilization by toroidal rotation is stronger for smaller edge safety factors.

  19. Volcanic hazards and public response

    Science.gov (United States)

    Peterson, Donald W.

    1988-05-01

    Although scientific understanding of volcanoes is advancing, eruptions continue to take a substantial toll of life and property. Some of these losses could be reduced by better advance preparation, more effective flow of information between scientists and public officials, and better understanding of volcanic behavior by all segments of the public. The greatest losses generally occur at volcanoes that erupt infrequently where people are not accustomed to dealing with them. Scientists sometimes tend to feel that the blame for poor decisions in emergency management lies chiefly with officials or journalists because of their failure to understand the threat. However, the underlying problem embraces a set of more complex issues comprising three pervasive factors. The first factor is the volcano: signals given by restless volcanoes are often ambiguous and difficult to interpret, especially at long-quiescent volcanoes. The second factor is people: people confront hazardous volcanoes in widely divergent ways, and many have difficulty in dealing with the uncertainties inherent in volcanic unrest. The third factor is the scientists: volcanologists correctly place their highest priority on monitoring and hazard assessment, but they sometimes fail to explain clearly their conclusions to responsible officials and the public, which may lead to inadequate public response. Of all groups in society, volcanologists have the clearest understanding of the hazards and vagaries of volcanic activity; they thereby assume an ethical obligation to convey effectively their knowledge to benefit all of society. If society resists, their obligation nevertheless remains. They must use the same ingenuity and creativity in dealing with information for the public that they use in solving scientific problems. When this falls short, even excellent scientific results may be nullified.

  20. Thermal vesiculation during volcanic eruptions.

    Science.gov (United States)

    Lavallée, Yan; Dingwell, Donald B; Johnson, Jeffrey B; Cimarelli, Corrado; Hornby, Adrian J; Kendrick, Jackie E; von Aulock, Felix W; Kennedy, Ben M; Andrews, Benjamin J; Wadsworth, Fabian B; Rhodes, Emma; Chigna, Gustavo

    2015-12-24

    Terrestrial volcanic eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the 'strength' of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of volcanic ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive

  1. Toitlustusettevõtete TOP 30 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Toitlustusettevõtete TOP 30 aastal 2002. Käibe TOP 30. Kasumi TOP 30. Käibe kasvu TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Omakapitali tootlikkuse TOP 30. Toitlustusettevõtete üldandmed. Toitlustusettevõtete finantsandmed

  2. Hiiumaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Hiiumaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Hiiumaa ettevõtete üld- ja finantsandmed; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20. Vt samas: Teeli Remmalg: Hiiumaal jätkub plastitööstuse võidumarss

  3. The search for the top quark

    International Nuclear Information System (INIS)

    Barbaro-Galtieri, A.

    1989-03-01

    This paper discusses the following topics: top search in the near future, general remarks, top search at HERA, searching for the top quarks at the Z 0 machines, finding the top at Lep II, top search in UA2, top search in UA1, and top search at CDF. 58 refs., 38 figs

  4. Toiduainetööstuste TOP 100

    Index Scriptorium Estoniae

    2006-01-01

    Toiduainetööstuse TOP. Vt. samas: Käibe TOP 10; Käibekasvu TOP 10; Kasumi TOP 10; Kasumi kasvu TOP 10; Rentaabluse TOP 10; Omakapitali tootlikkuse TOP 10; Toiduainetööstuse üld- ja finantsandmed

  5. Online-kaubanduse TOP aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Online-kaubanduse TOP aastal 2003. Käibe TOP 5. Käibe kasvu TOP 5. Rentaabluse TOP 5. Kasumi TOP 5. Kasumi kasvu TOP 5. Omakapitali tootlikkuse TOP 5. Lisa: TOPi koostamise metoodika. Online-kaubanduse firmade üldandmed. Online kaubanduse firmade finantsandmed

  6. Structural model of the Northern Latium volcanic area constrained by MT, gravity and aeromagnetic data

    Directory of Open Access Journals (Sweden)

    P. Gasparini

    1997-06-01

    Full Text Available The results of about 120 magnetotelluric soundings carried out in the Vulsini, Vico and Sabatini volcanic areas were modeled along with Bouguer and aeromagnetic anomalies to reconstruct a model of the structure of the shallow (less than 5 km of depth crust. The interpretations were constrained by the information gathered from the deep boreholes drilled for geothermal exploration. MT and aeromagnetic anomalies allow the depth to the top of the sedimentary basement and the thickness of the volcanic layer to be inferred. Gravity anomalies are strongly affected by the variations of morphology of the top of the sedimentary basement, consisting of a Tertiary flysch, and of the interface with the underlying Mesozoic carbonates. Gravity data have also been used to extrapolate the thickness of the neogenic unit indicated by some boreholes. There is no evidence for other important density and susceptibility heterogeneities and deeper sources of magnetic and/or gravity anomalies in all the surveyed area.

  7. TopView - ATLAS top physics analysis package

    CERN Document Server

    Shibata, A

    2007-01-01

    TopView is a common analysis package which is widely used in the ATLAS top physics working group. The package is fully based on the official ATLAS software Athena and EventView and playing a central role in the collaborative analysis model. It is a functional package which accounts for a broad range issues in implementing physics analysis. As well as being a modular framework suitable as a common workplace for collaborators, TopView implements numerous analysis tools including a complete top-antitop reconstruction and single top reconstruction. The package is currently used to produce common ntuple from Monte Carlo production and future use cases are under rapid development. In this paper, the design and ideas behind TopView and the performance of the analyses implemented in the package are presented with detailed documentation of the contents and instruction for using the package.

  8. Volcanism and associated hazards: the Andean perspective

    Science.gov (United States)

    Tilling, R. I.

    2009-12-01

    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (Colombia) killed about 25 000 people - the worst volcanic disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and Peru has spurred significant

  9. Naisjuhtidega ettevõtete TOP 70

    Index Scriptorium Estoniae

    2003-01-01

    Naisjuhtidega ettevõtete TOP 70. Käibe TOP 30. Käibe kasvu TOP 30. Kasumi TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP 30. Omakapitali tootlikkuse TOP 30. Nais- ja meesjuhtidega ettevõtted 2001. aasta 500 edukama ettevõtte hulgas. Naistegevjuhtidega firmade TOP 2001 ja 2002. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide TOP 20. Riigi- ja kohaliku omavalitsuse asutuste eelarve TOP 20. Riigi- ja kohaliku omavalitsuse asutuste töötajate arvu TOP 20. Naistegevjuhtidega firmade osakaal 2001. aastal. Riigi- ja kohaliku omavalitsuse asutuste naisjuhtide aastapalga TOP 20. Kommenteerib Tiina Raitviir.

  10. Electrostatic phenomena in volcanic eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Lane, S J; James, M R; Gilbert, J S, E-mail: s.lane@lancaster.ac.uk [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2011-06-23

    Electrostatic phenomena have long been associated with the explosive eruption of volcanoes. Lightning generated in volcanic plumes is a spectacular atmospheric electrical event that requires development of large potential gradients over distances of up to kilometres. This process begins as hydrated liquid rock (magma) ascends towards Earth's surface. Pressure reduction causes water supersaturation in the magma and the development of bubbles of supercritical water, where deeper than c. 1000 m, and water vapour at shallower depths that drives flow expansion. The generation of high strain rates in the expanding bubbly magma can cause it to fracture in a brittle manner, as deformation relaxation timescales are exceeded. The brittle fracture provides the initial charge separation mechanism, known as fractoemission. The resulting mixture of charged silicate particles and ions evolves over time, generating macro-scale potential gradients in the atmosphere and driving processes such as particle aggregation. For the silicate particles, aggregation driven by electrostatic effects is most significant for particles smaller than c. 100 {mu}m. Aggregation acts to change the effective aerodynamic behaviour of silicate particles, thus altering the sedimentation rates of particles from volcanic plumes from the atmosphere. The presence of liquid phases also promotes aggregation processes and lightning.

  11. Constraining Transient Climate Sensitivity Using Coupled Climate Model Simulations of Volcanic Eruptions

    KAUST Repository

    Merlis, Timothy M.; Held, Isaac M.; Stenchikov, Georgiy L.; Zeng, Fanrong; Horowitz, Larry W.

    2014-01-01

    Coupled climate model simulations of volcanic eruptions and abrupt changes in CO2 concentration are compared in multiple realizations of the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). The change in global-mean surface temperature (GMST) is analyzed to determine whether a fast component of the climate sensitivity of relevance to the transient climate response (TCR; defined with the 1%yr-1 CO2-increase scenario) can be estimated from shorter-time-scale climate changes. The fast component of the climate sensitivity estimated from the response of the climate model to volcanic forcing is similar to that of the simulations forced by abrupt CO2 changes but is 5%-15% smaller than the TCR. In addition, the partition between the top-of-atmosphere radiative restoring and ocean heat uptake is similar across radiative forcing agents. The possible asymmetry between warming and cooling climate perturbations, which may affect the utility of volcanic eruptions for estimating the TCR, is assessed by comparing simulations of abrupt CO2 doubling to abrupt CO2 halving. There is slightly less (~5%) GMST change in 0.5 × CO2 simulations than in 2 × CO2 simulations on the short (~10 yr) time scales relevant to the fast component of the volcanic signal. However, inferring the TCR from volcanic eruptions is more sensitive to uncertainties from internal climate variability and the estimation procedure. The response of the GMST to volcanic eruptions is similar in GFDL CM2.1 and GFDL Climate Model, version 3 (CM3), even though the latter has a higher TCR associated with a multidecadal time scale in its response. This is consistent with the expectation that the fast component of the climate sensitivity inferred from volcanic eruptions is a lower bound for the TCR.

  12. Constraining Transient Climate Sensitivity Using Coupled Climate Model Simulations of Volcanic Eruptions

    KAUST Repository

    Merlis, Timothy M.

    2014-10-01

    Coupled climate model simulations of volcanic eruptions and abrupt changes in CO2 concentration are compared in multiple realizations of the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). The change in global-mean surface temperature (GMST) is analyzed to determine whether a fast component of the climate sensitivity of relevance to the transient climate response (TCR; defined with the 1%yr-1 CO2-increase scenario) can be estimated from shorter-time-scale climate changes. The fast component of the climate sensitivity estimated from the response of the climate model to volcanic forcing is similar to that of the simulations forced by abrupt CO2 changes but is 5%-15% smaller than the TCR. In addition, the partition between the top-of-atmosphere radiative restoring and ocean heat uptake is similar across radiative forcing agents. The possible asymmetry between warming and cooling climate perturbations, which may affect the utility of volcanic eruptions for estimating the TCR, is assessed by comparing simulations of abrupt CO2 doubling to abrupt CO2 halving. There is slightly less (~5%) GMST change in 0.5 × CO2 simulations than in 2 × CO2 simulations on the short (~10 yr) time scales relevant to the fast component of the volcanic signal. However, inferring the TCR from volcanic eruptions is more sensitive to uncertainties from internal climate variability and the estimation procedure. The response of the GMST to volcanic eruptions is similar in GFDL CM2.1 and GFDL Climate Model, version 3 (CM3), even though the latter has a higher TCR associated with a multidecadal time scale in its response. This is consistent with the expectation that the fast component of the climate sensitivity inferred from volcanic eruptions is a lower bound for the TCR.

  13. Financial top 100

    International Nuclear Information System (INIS)

    Jaremko, G.

    1999-01-01

    The way in which the oil industry has rebounded from a difficult financial year was discussed. In 1998, oil prices fell by about 30 per cent from 1997 prices to average US$14.40. In the second quarter of 1999, the rebounding international markets raised oil prices by about one-third to an average US$17.60. Recent surveys have shown that the oil and gas industry will experience major changes in the decade ahead. It was forecasted that in 25 years, total Canadian oil production could near three million barrels per day, an increase of 36 per cent from today's 2.2 million. However, as conventional reserves are running out, production of conventional oil is expected to be diminished by about two-thirds. Naturally-occurring, light refinery-ready oil is forecasted to come mostly from the east coast, whereas western output will be dominated by oil sands. Natural gas will continue to be a huge growth opportunity in the west because of new pipeline expansions and exports to the United States. This paper presented a list of Canada's financial top 100 oil and gas companies which emerged with the best endurance. The list included statistics from 1997 and 1998 for gross revenues, total assets, net income, cash/operating activities, capital expenditures, closing share prices (with percentage change), and market capitalization. 1 fig., 1 tab

  14. Our top priority

    CERN Multimedia

    2012-01-01

    After three years of LHC running, we are still at the beginning of a long research programme with our flagship facility, and hopefully 4 July 2012 will go down in history as the date of one of many landmark discoveries spanning several years. CERN’s top priority for the next decade and more is the full exploitation of the LHC. With speculation about potential future facilities mounting in the light of the discovery of a new Higgs-like particle, it’s important to state that most clearly. Of course, this will rely on continued global collaboration, and it’s important that CERN engage constructively with other regions.   It is important to plan ahead, particularly since the lead times for new projects in particle physics are long, and our field is increasingly global in nature. That’s why the European particle physics community is currently engaged in updating its long-term strategy. Planning ahead allowed us to be ready technologically to build the LHC whe...

  15. Cenozoic volcanic rocks of Saudi Arabia

    Science.gov (United States)

    Coleman, R.G.; Gregory, R.T.; Brown, G.F.

    2016-01-01

    The Cenozoic volcanic rocks of Saudi Arabia cover about 90,000 km2, one of the largest areas of alkali olivine basalt in the world. These volcanic rocks are in 13 separate fields near the eastern coast of the Red Sea and in the western Arabian Peninsula highlands from Syria southward to the Yemen Arab Republic.

  16. Participative Design With Top Management

    DEFF Research Database (Denmark)

    Simonsen, Jesper

    2004-01-01

    meetings aimed at aligning top management with the supplier’s analysis. The article describes the MUST method’s anchoring principle and the technique of problem mapping supporting this principle. This participatory approach resulted in mutual learning processes with top management which is rarely reported...... on in the PD community. Top management participated by reviewing, challenging, and reformulating the IT designers’ central suppositions, assumptions, and hypotheses related to the causal relation between identified problems and suggested solutions....

  17. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    primitive basalts and trachybasalts but also more evolved samples from the retroarc region and the larger volcanoes Payún Matrú and Payún Liso are presented. The samples cover a broad range of compositions from intraplate lavas similar to ocean island basalts to arc andesites. A common feature found...... are isotopically similar to the Andean Southern Volcanic Zone arc rocks and their mantle source possibly resembled the source of South Atlantic N-MORB prior to addition of fluids and melts from the subduction channel. However, it must have been more enriched than the estimates of depleted upper mantle from...... the lithosphere is thinnest and possibly in areas of elevated mantle temperatures. The pyroxenite melts formed at deeper levels react with the surrounding peridotite and thereby changes composition leading to eruption of melts which experienced variable degrees of melt-peridotite interaction. This can presumably...

  18. Boosted top: experimental tools overview

    CERN Document Server

    Usai, Emanuele

    2015-01-01

    An overview of tools and methods for the reconstruction of high-boost top quark decays at the LHC is given in this report. The focus is on hadronic decays, in particular an overview of the current status of top quark taggers in physics analyses is presented. The most widely used jet substructure techniques, normally used in combination with top quark taggers, are reviewed. Special techniques to treat pileup in large cone jets are described, along with a comparison of the performance of several boosted top quark reconstruction techniques.

  19. Could stops lighten the top?

    International Nuclear Information System (INIS)

    Bilal, A.; Ellis, J.; Fogli, G.L.

    1990-01-01

    The analysis of the presently available electroweak data including radiative corrections in the standard model suggests that the top quark weighs more than the Z 0 . We examine whether squark loops in the minimal supersymmetric model, particularly those involving stops (partners of the top quark), could reduce substantially the preferred range of top quark masses. Given the present lower bounds on squark masses, we find that stop effects can reduce the central value of m t by at most a few GeV, although they do make a very heavy top quark increasingly unlikely. (orig.)

  20. Geomorphological Approach for Regional Zoning In The Merapi Volcanic Area

    Directory of Open Access Journals (Sweden)

    Langgeng Wahyu Santosa

    2013-07-01

    Full Text Available Geomorphologial approach can be used as the basic for identifying and analyzing the natural resources potentials, especially in volcanic landscape. Based on its geomorphology, Merapi volcanic landscape can be divided into 5 morphological units, i.e.: volcanic cone, volcanic slope, volcanic foot, volcanic foot plain, and fluvio-volcanic plain. Each of these morphological units has specific characteristic and natural resources potential. Based on the condition of geomorphology, the regional zoning can be compiled to support the land use planning and to maintain the conservation of environmental function in the Merapi Volcanic area.

  1. Large Volcanic Rises on Venus

    Science.gov (United States)

    Smrekar, Suzanne E.; Kiefer, Walter S.; Stofan, Ellen R.

    1997-01-01

    Large volcanic rises on Venus have been interpreted as hotspots, or the surface manifestation of mantle upwelling, on the basis of their broad topographic rises, abundant volcanism, and large positive gravity anomalies. Hotspots offer an important opportunity to study the behavior of the lithosphere in response to mantle forces. In addition to the four previously known hotspots, Atla, Bell, Beta, and western Eistla Regiones, five new probable hotspots, Dione, central Eistla, eastern Eistla, Imdr, and Themis, have been identified in the Magellan radar, gravity and topography data. These nine regions exhibit a wider range of volcano-tectonic characteristics than previously recognized for venusian hotspots, and have been classified as rift-dominated (Atla, Beta), coronae-dominated (central and eastern Eistla, Themis), or volcano-dominated (Bell, Dione, western Eistla, Imdr). The apparent depths of compensation for these regions ranges from 65 to 260 km. New estimates of the elastic thickness, using the 90 deg and order spherical harmonic field, are 15-40 km at Bell Regio, and 25 km at western Eistla Regio. Phillips et al. find a value of 30 km at Atla Regio. Numerous models of lithospheric and mantle behavior have been proposed to interpret the gravity and topography signature of the hotspots, with most studies focusing on Atla or Beta Regiones. Convective models with Earth-like parameters result in estimates of the thickness of the thermal lithosphere of approximately 100 km. Models of stagnant lid convection or thermal thinning infer the thickness of the thermal lithosphere to be 300 km or more. Without additional constraints, any of the model fits are equally valid. The thinner thermal lithosphere estimates are most consistent with the volcanic and tectonic characteristics of the hotspots. Estimates of the thermal gradient based on estimates of the elastic thickness also support a relatively thin lithosphere (Phillips et al.). The advantage of larger estimates of

  2. Edge Pedestal Control in Quiescent H-Mode Discharges in DIII-D Using Co Plus Counter Neutral Beam Injection

    International Nuclear Information System (INIS)

    Burrell, K.H.; Osborne, T.H.; Snyder, P.B.; West, W.P.; Chu, M.S.; Fenstermacher, M.E.; Gohil, P.; Solomon, W.M.

    2008-01-01

    We have made two significant discoveries in our recent studies of quiescent H-mode (QH-mode) plasmas in DIII-D. First, we have found that we can control the edge pedestal density and pressure by altering the edge particle transport through changes in the edge toroidal rotation. This allows us to adjust the edge operating point to be close to, but below the ELM stability boundary, maintaining the ELM-free state while allowing up to a factor of two increase in edge pressure. The ELM boundary is significantly higher in more strongly shaped plasmas, which broadens the operating space available for QH-mode and leads to improved core performance. Second, for the first time on any tokamak, we have created QH-mode plasmas with strong edge co-rotation; previous QH-modes in all tokamaks had edge counter rotation. This result demonstrates that counter NBI and edge counter rotation are not essential conditions for QH-mode. Both these investigations benefited from the edge stability predictions based on peeling-ballooning mode theory. The broadening of the ELM-stable region with plasma shaping is predicted by that theory. The theory has also been extended to provide a model for the edge harmonic oscillation (EHO) that regulates edge transport in the QH-mode. Many of the features of that theory agree with the experimental results reported either previously or in the present paper. One notable example is the prediction that co-rotating QH-mode is possible provided sufficient shear in the edge rotation can be created

  3. Direct evidence of stationary zonal flows and critical gradient behavior for Er during formation of the edge pedestal in JET

    Science.gov (United States)

    Hillesheim, Jon

    2015-11-01

    High spatial resolution measurements with Doppler backscattering in JET have provided new insights into the development of the edge radial electric field during pedestal formation. The characteristics of Er have been studied as a function of density at 2.5 MA plasma current and 3 T toroidal magnetic field. We observe fine-scale spatial structure in the edge Er well prior to the LH transition, consistent with stationary zonal flows. Zonal flows are a fundamental mechanism for the saturation of turbulence and this is the first direct evidence of stationary zonal flows in a tokamak. The radial wavelength of the zonal flows systematically decreases with density. The zonal flows are clearest in Ohmic conditions, weaker in L-mode, and absent in H-mode. Measurements also show that after neutral beam heating is applied, the edge Er builds up at a constant gradient into the core during L-mode, at radii where Er is mainly due to toroidal velocity. The local stability of velocity shear driven turbulence, such as the parallel velocity gradient mode, will be assessed with gyrokinetic simulations. This critical Er shear persists across the LH transition into H-mode. Surprisingly, a reduction in the apparent magnitude of the Er well depth is observed directly following the LH transition at high densities. Establishing the physics basis for the LH transition is important for projecting scalings to ITER and these observations challenge existing models based on increased Er shear or strong zonal flows as the trigger for the transition. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

  4. Dinasour extinction and volcanic activity

    Science.gov (United States)

    Gledhill, J. A.

    There is at present some controversy about the reason for the mass extinction of dinosaurs and other forms of life at the end of the Cretaceous. A suggestion by Alvarez et al. [1980] that this was due to the collision of the earth with a meteorite 10 km or so in diameter has excited considerable interest [Silver and Schultz, 1982] and also some criticism [Stanley, 1984]. A recent publication [Wood, 1984] describing the catastrophic effects of a relatively minor lava flow in Iceland suggests that intense volcanic activity could have played a large part in the extinctions. In this letter it is pointed out that the Deccan lava flows in India took place in the appropriate time and may well have been of sufficient magnitude to be a major factor in the Cretaceous-Tertiary (C-T) boundary catastrophe.

  5. Maja Valles, Mars: A Multi-Source Fluvio-Volcanic Outflow Channel System

    Science.gov (United States)

    Keske, A.; Christensen, P. R.

    2017-12-01

    The resemblance of martian outflow channels to the channeled scablands of the Pacific Northwest has led to general consensus that they were eroded by large-scale flooding. However, the observation that many of these channels are coated in lava issuing from the same source as the water source has motivated the alternative hypothesis that the channels were carved by fluid, turbulent lava. Maja Valles is a circum-Chryse outflow channel whose origin was placed in the late Hesperian by Baker and Kochel (1979), with more recent studies of crater density variations suggesting that its formation history involved multiple resurfacing events (Chapman et al., 2003). In this study, we have found that while Maja Valles indeed host a suite of standard fluvial landforms, its northern portion is thinly coated with lava that has buried much of the older channel landforms and overprinted them with effusive flow features, such as polygons and bathtub rings. Adjacent to crater pedestals and streamlined islands are patches of dark, relatively pristine material pooled in local topographic lows that we have interpreted as ponds of lava remaining from one or more fluid lava flows that flooded the channel system and subsequently drained, leaving marks of the local lava high stand. Despite the presence of fluvial landforms throughout the valles, lava flow features exist in the northern reaches of the system alone, 500-1200 km from the channels' source. The flows can instead be traced to a collection of vents in Lunae Plaum, west of the valles. In previously studied fluvio-volcanic outflow systems, such as Athabasca Valles, the sources of the volcanic activity and fluvial activity have been indistinguishable. In contrast, Maja Valles features numerous fluvio-volcanic landforms bearing similarity to those identified in other channel systems, yet the source of its lava flows is distinct from the source of its channels. Furthermore, in the absence of any channels between the source of the lava

  6. Is there a geochemical link between volcanic and plutonic rocks in the Organ Mountains caldera?

    Science.gov (United States)

    Memeti, V.; Davidson, J.

    2013-12-01

    Results from separate volcanic and plutonic studies have led to inconsistent conclusions regarding the origins and thus links between volcanic and plutonic systems in continental arcs and the magmatic processes and time scales responsible for their compositional variations. Some have suggested that there is a geochemical and geochronological disconnect between volcanic and plutonic rocks and hence have questioned the existence of magma mush columns beneath active volcanoes. Investigating contemporary volcanic and plutonic rocks that are spatially connected is thus critical in exploring these issues. The ca. 36 Ma Organ Mountains caldera in New Mexico, USA, represents such a system exposing contemporaneous volcanic and plutonic rocks juxtaposed at the surface due to tilting during extensional tectonics along the Rio Grande Rift. Detailed geologic and structural mapping [1] and 40Ar/39Ar ages of both volcanics and plutons [2] demonstrate the spatial and temporal connection of both rock types with active magmatism over >2.5 myr. Three caldera-forming ignimbrites erupted within 600 kyr [2] from this system with a total erupted volume of 500-1,000 km3 as well as less voluminous pre- and post-caldera trachyte and andesite lavas. The ignimbrite sequence ranges from a crystal-poor, high-SiO2 rhyolite at the base to a more crystal-rich, low-SiO2 rhyolite at the top. Compositional zoning with quartz-monzonite at the base grading to syenite and alaskite at the top is also found in the Organ Needle pluton, the main intrusion, which is interpreted to be the source for the ignimbrites [1]. Other contemporaneous and slightly younger plutons have dioritic to leucogranitic compositions. We examined both volcanic and plutonic rocks with petrography and their textural variations with color cathodoluminescence, and used whole rock element and Sr, Nd and Pb isotope geochemistry to constrain magma compositions and origins. Electron microprobe analyses on feldspars have been completed to

  7. Lava and Life: New investigations into the Carson Volcanics, lower Kimberley Basin, north Western Australia

    Science.gov (United States)

    Orth, Karin; Phillips, Chris; Hollis, Julie

    2014-05-01

    The Carson Volcanics are the only volcanic unit in the Paleoproterozoic Kimberley Basin and are part of a poorly studied Large Igneous Province (LIP) that was active at 1790 Ma. New work focussing on this LIP in 2012 and 2013 involved helicopter-supported traverses and sampling of the Carson Volcanics in remote areas near Kalumburu in far north Western Australia's Kimberley region. The succession is widespread and flat lying to gently dipping. It consists of three to six basalt units with intercalated sandstone and siltstone. The basalts are 20-40 m thick, but can be traced up to 60 km along strike. The basalt can be massive or amygdaloidal and commonly display polygonal to subhorizontal and rare vertical columnar jointing. Features of the basalt include ropy lava tops and basal pipe vesicles consistent with pahoehoe lavas. The intercalated cross-bedded quartzofeldspathic sandstone and siltstone vary in thickness up to 40 m and can be traced up to 40 km along strike. Peperite is common and indicates interaction between wet, unconsolidated sediment and hot lava. Stromatolitic chert at the top of the formation represents the oldest life found within the Kimberley region. Mud cracks evident in the sedimentary rocks, and stromatolites suggest an emergent broad tidal flat environment. The volcanics were extruded onto a wide marginal margin setting subject to frequent flooding events. Thickening of the volcanic succession south and the palaeocurrents in the underlying King Leopold Sandstone and the overlying Warton Sandstone suggest that this shelf sloped to the south. The type of basalt and the basalt morphology indicate a low slope gradient of about 1°.

  8. Wave Engine Topping Cycle Assessment

    Science.gov (United States)

    Welch, Gerard E.

    1996-01-01

    The performance benefits derived by topping a gas turbine engine with a wave engine are assessed. The wave engine is a wave rotor that produces shaft power by exploiting gas dynamic energy exchange and flow turning. The wave engine is added to the baseline turboshaft engine while keeping high-pressure-turbine inlet conditions, compressor pressure ratio, engine mass flow rate, and cooling flow fractions fixed. Related work has focused on topping with pressure-exchangers (i.e., wave rotors that provide pressure gain with zero net shaft power output); however, more energy can be added to a wave-engine-topped cycle leading to greater engine specific-power-enhancement The energy addition occurs at a lower pressure in the wave-engine-topped cycle; thus the specific-fuel-consumption-enhancement effected by ideal wave engine topping is slightly lower than that effected by ideal pressure-exchanger topping. At a component level, however, flow turning affords the wave engine a degree-of-freedom relative to the pressure-exchanger that enables a more efficient match with the baseline engine. In some cases, therefore, the SFC-enhancement by wave engine topping is greater than that by pressure-exchanger topping. An ideal wave-rotor-characteristic is used to identify key wave engine design parameters and to contrast the wave engine and pressure-exchanger topping approaches. An aerodynamic design procedure is described in which wave engine design-point performance levels are computed using a one-dimensional wave rotor model. Wave engines using various wave cycles are considered including two-port cycles with on-rotor combustion (valved-combustors) and reverse-flow and through-flow four-port cycles with heat addition in conventional burners. A through-flow wave cycle design with symmetric blading is used to assess engine performance benefits. The wave-engine-topped turboshaft engine produces 16% more power than does a pressure-exchanger-topped engine under the specified topping

  9. A fluid model for the edge pressure pedestal height and width in tokamaks based on the transport constraint of particle, energy, and momentum balance

    Energy Technology Data Exchange (ETDEWEB)

    Stacey, W. M., E-mail: weston.stacey@nre.gatech.edu [Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2016-06-15

    A fluid model for the tokamak edge pressure profile required by the conservation of particles, momentum and energy in the presence of specified heating and fueling sources and electromagnetic and geometric parameters has been developed. Kinetics effects of ion orbit loss are incorporated into the model. The use of this model as a “transport” constraint together with a “Peeling-Ballooning (P-B)” instability constraint to achieve a prediction of edge pressure pedestal heights and widths in future tokamaks is discussed.

  10. Status of the top quark: Top production cross section and top properties

    Energy Technology Data Exchange (ETDEWEB)

    Boisvert, V.; /Rochester U.

    2006-08-01

    This report describes the latest cross section and property measurements associated with the top quark at the Tevatron Run II. The largest data sample used is 760 pb{sup -1} of integrated luminosity. Due to its large mass, the top quark might be involved in the process of electroweak symmetry breaking, making it a useful probe for signs of new physics.

  11. Volcanic Plume Measurements with UAV (Invited)

    Science.gov (United States)

    Shinohara, H.; Kaneko, T.; Ohminato, T.

    2013-12-01

    Volatiles in magmas are the driving force of volcanic eruptions and quantification of volcanic gas flux and composition is important for the volcano monitoring. Recently we developed a portable gas sensor system (Multi-GAS) to quantify the volcanic gas composition by measuring volcanic plumes and obtained volcanic gas compositions of actively degassing volcanoes. As the Multi-GAS measures variation of volcanic gas component concentrations in the pumped air (volcanic plume), we need to bring the apparatus into the volcanic plume. Commonly the observer brings the apparatus to the summit crater by himself but such measurements are not possible under conditions of high risk of volcanic eruption or difficulty to approach the summit due to topography etc. In order to overcome these difficulties, volcanic plume measurements were performed by using manned and unmanned aerial vehicles. The volcanic plume measurements by manned aerial vehicles, however, are also not possible under high risk of eruption. The strict regulation against the modification of the aircraft, such as installing sampling pipes, also causes difficulty due to the high cost. Application of the UAVs for the volcanic plume measurements has a big advantage to avoid these problems. The Multi-GAS consists of IR-CO2 and H2O gas analyzer, SO2-H2O chemical sensors and H2 semiconductor sensor and the total weight ranges 3-6 kg including batteries. The necessary conditions of the UAV for the volcanic plumes measurements with the Multi-GAS are the payloads larger than 3 kg, maximum altitude larger than the plume height and installation of the sampling pipe without contamination of the exhaust gases, as the exhaust gases contain high concentrations of H2, SO2 and CO2. Up to now, three different types of UAVs were applied for the measurements; Kite-plane (Sky Remote) at Miyakejima operated by JMA, Unmanned airplane (Air Photo Service) at Shinomoedake, Kirishima volcano, and Unmanned helicopter (Yamaha) at Sakurajima

  12. New directions in top physics

    Energy Technology Data Exchange (ETDEWEB)

    Schell, Torben Karl

    2017-02-01

    The top quark plays an important role for many aspects of particle physics. The coupling of the Higgs boson to top quarks is a key parameter to probe electroweak symmetry breaking and is important for the evolution of the Higgs potential to high energies. In addition, many models of physics beyond the Standard Model predict heavy particles that decay to top-quark pairs. Furthermore, the unexplained hierarchy of fermion masses culminates in the large top-quark mass. In this thesis, we consider resonance searches based on top quarks in the fully hadronic final state. We employ multivariate techniques in form of boosted decision trees and add several improvements to the original HEPTopTagger algorithm. These modifications and extensions result in the new HEPTopTagger2. The achieved improvements are used to estimate the precision to which the top Yukawa coupling can be measured at a future 100 TeV proton-proton collider in the fully hadronic final state of t anti tH production. We find that at such a collider a precision measurement of the top Yukawa coupling to 1% should be possible. The statistical precision is backed up by demonstrating that in the ratio σ(t anti tH)/σ(t anti tZ) theoretical uncertainties cancel to below-percent level. Finally, we propose a Froggatt-Nielsen-type model to address the hierarchy of fermion masses in the Standard Model and determine current and projected bounds on the available parameter space.

  13. Impact of solar versus volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

    Science.gov (United States)

    Anet, J. G.; Muthers, S.; Rozanov, E. V.; Raible, C. C.; Stenke, A.; Shapiro, A. I.; Brönnimann, S.; Arfeuille, F.; Brugnara, Y.; Beer, J.; Steinhilber, F.; Schmutz, W.; Peter, T.

    2014-05-01

    The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles versus volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, AD 1780-1840). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere-ocean chemistry-climate model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decreased global mean temperature by up to 0.5 K for 2-3 years after the eruption. However, while the volcanic effect is clearly discernible in the Southern Hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ Dalton Minimum. This downscales the importance of top-down processes (stemming from changes at λ 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease in the ocean heat content (OHC) between 0 and 300 m in depth, whereas the changes in irradiance at λ < 250 nm or in energetic particles have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8-15 years after volcanic eruption, while the solar signal and the different

  14. Impact of solar vs. volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

    Science.gov (United States)

    Anet, J. G.; Muthers, S.; Rozanov, E. V.; Raible, C. C.; Stenke, A.; Shapiro, A. I.; Brönnimann, S.; Arfeuille, F.; Brugnara, Y.; Beer, J.; Steinhilber, F.; Schmutz, W.; Peter, T.

    2013-11-01

    The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles vs. volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, 1780-1840 AD). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere-ocean chemistry-climate-model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decrease global mean temperature by up to 0.5 K for 2-3 yr after the eruption. However, while the volcanic effect is clearly discernible in the southern hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree-ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ Dalton Minimum. This downscales the importance of top-down processes (stemming from changes at λ 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease of the ocean heat content (OHC) between the 0 and 300 m of depth, whereas the changes in irradiance at λ < 250 nm or in energetic particle have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8-15 yr after volcanic eruption, while the solar signal and the different

  15. The aggregation efficiency of very fine volcanic ash

    Science.gov (United States)

    Del Bello, E.; Taddeucci, J.; Scarlato, P.

    2013-12-01

    Explosive volcanic eruptions can discharge large amounts of very small sized pyroclasts (under 0.090 mm) into the atmosphere that may cause problems to people, infrastructures and environment. The transport and deposition of fine ash are ruled by aggregation that causes premature settling of fine ash and, as consequence, significantly reduces the concentration of airborne material over long distances. Parameterizing the aggregation potential of fine ash is then needed to provide accurate modelling of ash transport and deposition from volcanic plumes. Here we present the first results of laboratory experiments investigating the aggregation efficiency of very fine volcanic particles. Previous laboratory experiments have shown that collision kinetic and relative humidity provide the strongest effect on aggregation behaviour but were only limited to particles with size > 0.125 mm. In our work, we focus on natural volcanic ash at ambient humidity with particles size aggregation potential. Two types of ash were used in our experiments: fresh ash, collected during fall-out from a recent plume-forming eruption at Sakurajima (Japan -July 2013) and old ash, collected from fall-out tephra deposits at Campi Flegrei (Italy, ca. 10 ka), to account for the different chemical composition and morphoscopic effects of altered ash on aggregation efficiency. Total samples were hand sieved to obtain three classes with unimodal grain size distributions (sieved from the top of a transparent tank where a fan, placed at the bottom, allows turbulent dispersion of particles. Collision and sticking of particles on a vertical glass slide were filmed with a high speed cameras at 6000 fps. Our lenses arrangement provide high image resolution allowing to capture particles down to 0.005 mm in diameter. Video sequences of particles motion and collision were then processed with image analysis and particle tracking tools to determine i) the particle number density and ii) the grain size distribution

  16. Genesis of petroduric and petrocalcic horizons in Latinamerica volcanic soils

    Science.gov (United States)

    Quantin, Paul

    2010-05-01

    Introduction. In Latinamerica, from Mexico to Chile, there are indurated volcanic soils horizons, named 'tepetate' in Mexico or cangahua in the Andes Mountains. Apart from original volcanic tuffs, these horizons were produced by pedogenesis: either through a former weathering of volcanic ash layers into fragic and later to petrocalcic horizons; or after a former soil formation through a second process of transformation from clayey volcanic soils to silicified petroduric horizons. This oral presentation will briefly deal with the formation of petroduric horizons in Mexico and petrocalcic horizon in Ecuador. Petroduric horizon genesis in Mexico. A soil climato-toposequence, near to Veracruz (Rossignol & Quantin, 1997), shows downwards an evolution from a ferralic Nitisol to a petroduric Durisol. A Durisol profile comports these successive horizons: at the top A and Eg, then columnar Btg-sim, laminar Bt-sim , prismatic Bsim, plinthite Cg, over andesite lava flow. Among its main features are especially recorded: clay mineralogy, microscopy and HRTEM. These data show: an increase in cristobalite at the expenses of 0.7 nm halloysite in Egsiltans, laminar Bt-sim, around or inside the columns or prisms of Btg-sim and Bsimhorizons. HRTEM (Elsass & al 2000) on ultra thin sections reveals an 'epigenesis' of clay sheets by amorphous silica, to form successively A-opal, Ct-opal and microcrystalline cristobalite. From these data and some groundwater chemical analyses, a scenario of duripan formation from a past clayey Nitisol is inferred: clay eluviation-illuviation process? alternate redoximorphy? clay degradation, Al leaching and Si accumulation, to form successively A-opal, Ct-opal and cristobalite. Petrocalcic horizon genesis in Ecuador. A soil climato-toposequence on pyroclastic flows, near to Bolivar in Ecuador (Quantin & Zebrowski, 1997), shows downwards the evolution from fragic-eutric-vitric Cambisols to petrocalcic-vitric Phaeozems, at the piedmont under semi

  17. Volcanic Ash Advisory Database, 1983-2003

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanic ash is a significant hazard to aviation and can also affect global climate patterns. To ensure safe navigation and monitor possible climatic impact, the...

  18. Age of the Auckland Volcanic Field

    International Nuclear Information System (INIS)

    Lindsay, J.; Leonard, G.S.

    2009-01-01

    In 2008 a multi-disciplinary research programme was launched, a GNS Science-University of Auckland collaboration with the aim of DEtermining VOlcanic Risk in Auckland (DEVORA). A major aspiration of DEVORA is development of a probabilistic hazard model for the Auckland Volcanic Field (AVF). This will be achieved by investigating past eruption magnitude-frequency relationships and comparing these with similar data from analogous volcanic fields. A key data set underpinning this is an age database for the AVF. To this end a comprehensive dating campaign is planned as part of DEVORA. This report, Age of the Auckland Volcanic Field, is a synthesis of all currently available age data for the AVF. It represents one of several reports carried out as part of the 'synthesis' phase of DEVORA, whereby existing data from all previous work is collated and summarised, so that gaps in current knowledge can be identified and addressed. (author). 60 refs., 7 figs., 31 tabs.

  19. Volcanic eruptions are cooling the earth

    International Nuclear Information System (INIS)

    Groenaas, Sigbjoern

    2005-01-01

    The article discusses how volcanic eruptions may influence the climate. The environmental impacts both on the earth surface and the atmosphere are surveyed. Some major eruptions in modern times are mentioned

  20. Stochastic Modeling of Past Volcanic Crises

    Science.gov (United States)

    Woo, Gordon

    2018-01-01

    The statistical foundation of disaster risk analysis is past experience. From a scientific perspective, history is just one realization of what might have happened, given the randomness and chaotic dynamics of Nature. Stochastic analysis of the past is an exploratory exercise in counterfactual history, considering alternative possible scenarios. In particular, the dynamic perturbations that might have transitioned a volcano from an unrest to an eruptive state need to be considered. The stochastic modeling of past volcanic crises leads to estimates of eruption probability that can illuminate historical volcanic crisis decisions. It can also inform future economic risk management decisions in regions where there has been some volcanic unrest, but no actual eruption for at least hundreds of years. Furthermore, the availability of a library of past eruption probabilities would provide benchmark support for estimates of eruption probability in future volcanic crises.

  1. Application of wire sawing method to decommissioning of nuclear power plant. Cutting test with turbine pedestal of thermal power plant

    International Nuclear Information System (INIS)

    Hasegawa, Hideki; Uchiyama, Noriyuki; Sugiyama, Kazuya; Yamashita, Yoshitaka; Watanabe, Morishige

    1995-01-01

    It is very important to reduce radioactive waste volume, and to reduce radiation dose to workers and to the public during dismantling of the activated concrete in the decommissioning stage of a nuclear power plant. For the above, we studied a dismantling method which can separate activated concrete from non-activated concrete safely and effectively. Considering the state of legal regulation about radioactive waste disposal, and the state of developing of decommissioning technologies, we come to a conclusion that wire sawing method is feasible as a concrete cutting method. This study was carried out to evaluate the availability of the wire sawing method to dismantling of concrete structures of nuclear power plants. This study consists of concrete cutting rate test and concrete block cutting test. The former is to obtain data about cutting rate with various steel ratios while the latter is to obtain data about working time and man hour of the whole work with wire sawing. Thirty-six year old turbine pedestal of a thermal power plant was selected as a test piece to simulate actual decommissioning work of nuclear power plant, taking its massive concrete volume and age. Taking account of the handling in the building, the wire sawing machine with motor driven was used in this study considering that it did not produce exhaust gas. The concrete cutting rate test was performed with parameter of steel ratio in the concrete, wire tension and cutting direction. In the concrete block cutting test, imaging the actual cutting situation, cubic blocks which side was approximately 1 meter were taken out, and a large block to be cut and to be taken out is a section of 1m x 1.5m x 10m. Test results are shown below. The difference of cutting rate was mainly caused by the difference of reinforcement steel ratio. Working time data of installation, removal of machines and cutting were obtained. Data on secondary waste (dust, drainage and sludge) and environmental effect (noise and

  2. Imaging volcanic CO2 and SO2

    Science.gov (United States)

    Gabrieli, A.; Wright, R.; Lucey, P. G.; Porter, J. N.

    2017-12-01

    Detecting and quantifying volcanic carbon dioxide (CO2) and sulfur dioxide (SO2) emissions is of relevance to volcanologists. Changes in the amount and composition of gases that volcanoes emit are related to subsurface magma movements and the probability of eruptions. Volcanic gases and related acidic aerosols are also an important atmospheric pollution source that create environmental health hazards for people, animals, plants, and infrastructures. For these reasons, it is important to measure emissions from volcanic plumes during both day and night. We present image measurements of the volcanic plume at Kīlauea volcano, HI, and flux derivation, using a newly developed 8-14 um hyperspectral imaging spectrometer, the Thermal Hyperspectral Imager (THI). THI is capable of acquiring images of the scene it views from which spectra can be derived from each pixel. Each spectrum contains 50 wavelength samples between 8 and 14 um where CO2 and SO2 volcanic gases have diagnostic absorption/emission features respectively at 8.6 and 14 um. Plume radiance measurements were carried out both during the day and the night by using both the lava lake in the Halema'uma'u crater as a hot source and the sky as a cold background to detect respectively the spectral signatures of volcanic CO2 and SO2 gases. CO2 and SO2 path-concentrations were then obtained from the spectral radiance measurements using a new Partial Least Squares Regression (PLSR)-based inversion algorithm, which was developed as part of this project. Volcanic emission fluxes were determined by combining the path measurements with wind observations, derived directly from the images. Several hours long time-series of volcanic emission fluxes will be presented and the SO2 conversion rates into aerosols will be discussed. The new imaging and inversion technique, discussed here, are novel allowing for continuous CO2 and SO2 plume mapping during both day and night.

  3. Top quark properties at ATLAS

    CERN Document Server

    Dilip, Jana

    2008-01-01

    The ATLAS potential for the study of the top quark properties and physics beyond the Standard Model in the top quark sector, is described. The measurements of the top quark charge, the spin and spin correlations, the Standard Model decay (t-> bW), rare top quark decays associated to flavour changing neutral currents (t-> qX with X = gluon, Z, photon) and ttbar resonances are discussed. The sensitivity of the ATLAS experiment is estimated for an expected luminosity of 1fb-1 at the LHC. The full simulation of the ATLAS detector is used. For the Standard Model measurements the expected precision is presented. For the tests of physics beyond the Standard Model, the 5 sigma discovery potential (in the presence of a signal) and the 95% Confidence Level (CL) limit (in the absence of a signal) are given.

  4. Võrumaa ettevõtete TOP 50 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Võrumaa ettevõtete TOP 50 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Võrumaa firmade üld- ja finantsandmed

  5. Post-Eocene volcanics of the Abazar district, Qazvin, Iran: Mineralogical and geochemical evidence for a complex magmatic evolution

    Science.gov (United States)

    Asiabanha, A.; Bardintzeff, J. M.; Kananian, A.; Rahimi, G.

    2012-02-01

    The style of volcanism of post-Eocene volcanism in the Alborz zone of northern Iran is different to that of Eocene volcanism (Karaj Formation). Indeed, the volcanic succession of the Abazar district, located in a narrow volcanic strip within the Alborz magmatic assemblage, is characterized by distinct mineralogical and chemical compositions linked to a complex magmatic evolution. The succession was produced by explosive eruptions followed by effusive eruptions. Two main volcanic events are recognized: (1) a thin rhyolitic ignimbritic sheet underlain by a thicker lithic breccia, and (2) lava flows including shoshonite, latite, and andesite that overlie the first event across a reddish soil horizon. Plagioclase in shoshonite (An 48-92) shows normal zoning, whereas plagioclase in latite and andesite (An 48-75) has a similar composition but shows reverse and oscillatory zoning. QUILF temperature calculations for shoshonites and andesites yield temperatures of 1035 °C and 1029 °C, respectively. The geothermometers proposed by Ridolfi et al. (2010) and Holland and Blundy (1994) yield temperatures of 960 °C and 944 °C for latitic lava, respectively. The samples of volcanic rock show a typical geochemical signature of the continental arc regime, but the andesites clearly differ from the shoshonites, the latites and the rhyolites. The mineralogical and chemical characteristics of these rocks are explained by the following petrogenesis: (1) intrusion of a hot, mantle-depth mafic (shoshonitic) magma, which differentiated in the magma chamber to produce a latitic and then a rhyolitic liquid; (2) rhyolitic ignimbritic eruptions from the top of the magma chamber, following by shoshonitic and then latitic extrusions; (3) magma mingling between the latitic and andesitic magmas, as indicated by the occurrence of andesite clasts within the latite; and (4) andesitic effusions. The youngest volcanic events in the Alborz zone show a close chemical relationship with continental arc

  6. Characteristics of volcanic reservoirs and distribution rules of effective reservoirs in the Changling fault depression, Songliao Basin

    Directory of Open Access Journals (Sweden)

    Pujun Wang

    2015-11-01

    Full Text Available In the Songliao Basin, volcanic oil and gas reservoirs are important exploration domains. Based on drilling, logging, and 3D seismic (1495 km2 data, 546 sets of measured physical properties and gas testing productivity of 66 wells in the Changling fault depression, Songliao Basin, eruptive cycles and sub-lithofacies were distinguished after lithologic correction of the 19,384 m volcanic well intervals, so that a quantitative analysis was conducted on the relation between the eruptive cycles, lithologies and lithofacies and the distribution of effective reservoirs. After the relationship was established between lithologies, lithofacies & cycles and reservoir physical properties & oil and gas bearing situations, an analysis was conducted on the characteristics of volcanic reservoirs and the distribution rules of effective reservoirs. It is indicated that 10 eruptive cycles of 3 sections are totally developed in this area, and the effective reservoirs are mainly distributed at the top cycles of eruptive sequences, with those of the 1st and 3rd Members of Yingcheng Formation presenting the best reservoir properties. In this area, there are mainly 11 types of volcanic rocks, among which rhyolite, rhyolitic tuff, rhyolitic tuffo lava and rhyolitic volcanic breccia are the dominant lithologies of effective reservoirs. In the target area are mainly developed 4 volcanic lithofacies (11 sub-lithofacies, among which upper sub-lithofacies of effusive facies and thermal clastic sub-lithofacies of explosion lithofacies are predominant in effective reservoirs. There is an obvious corresponding relationship between the physical properties of volcanic reservoirs and the development degree of effective reservoirs. The distribution of effective reservoirs is controlled by reservoir physical properties, and the formation of effective reservoirs is influenced more by porosity than by permeability. It is concluded that deep volcanic gas exploration presents a good

  7. Local and remote infrasound from explosive volcanism

    Science.gov (United States)

    Matoza, R. S.; Fee, D.; LE Pichon, A.

    2014-12-01

    Explosive volcanic eruptions can inject large volumes of ash into heavily travelled air corridors and thus pose a significant societal and economic hazard. In remote volcanic regions, satellite data are sometimes the only technology available to observe volcanic eruptions and constrain ash-release parameters for aviation safety. Infrasound (acoustic waves ~0.01-20 Hz) data fill this critical observational gap, providing ground-based data for remote volcanic eruptions. Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. Advances in infrasound technology and the efficient propagation of infrasound in the atmosphere therefore greatly enhance our ability to monitor volcanoes in remote regions such as the North Pacific Ocean. Infrasound data can be exploited to detect, locate, and provide detailed chronologies of the timing of explosive volcanic eruptions for use in ash transport and dispersal models. We highlight results from case studies of multiple eruptions recorded by the International Monitoring System and dedicated regional infrasound networks (2008 Kasatochi, Alaska, USA; 2008 Okmok, Alaska, USA; 2009 Sarychev Peak, Kuriles, Russian Federation; 2010 Eyjafjallajökull, Icleand) and show how infrasound is currently used in volcano monitoring. We also present progress towards characterizing and modeling the variability in source mechanisms of infrasound from explosive eruptions using dedicated local infrasound field deployments at volcanoes Karymsky, Russian Federation and Sakurajima, Japan.

  8. Uncovering the single top: observation of electroweak top quark production

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, Jorge Armando [Michigan State Univ., East Lansing, MI (United States)

    2009-01-01

    The top quark is generally produced in quark and anti-quark pairs. However, the Standard Model also predicts the production of only one top quark which is mediated by the electroweak interaction, known as 'Single Top'. Single Top quark production is important because it provides a unique and direct way to measure the CKM matrix element Vtb, and can be used to explore physics possibilities beyond the Standard Model predictions. This dissertation presents the results of the observation of Single Top using 2.3 fb-1 of Data collected with the D0 detector at the Fermilab Tevatron collider. The analysis includes the Single Top muon+jets and electron+jets final states and employs Boosted Decision Tress as a method to separate the signal from the background. The resulting Single Top cross section measurement is: (1) σ(p$\\bar{p}$→ tb + X, tqb + X) = 3.74-0.74+0.95 pb, where the errors include both statistical and systematic uncertainties. The probability to measure a cross section at this value or higher in the absence of signal is p = 1.9 x 10-6. This corresponds to a standard deviation Gaussian equivalence of 4.6. When combining this result with two other analysis methods, the resulting cross section measurement is: (2) σ(p$\\bar{p}$ → tb + X, tqb + X) = 3.94 ± 0.88 pb, and the corresponding measurement significance is 5.0 standard deviations.

  9. Search for Top in TOTEM

    CERN Document Server

    Corrales, Alonso

    2017-01-01

    The work assigned to me during this summer (from June 19th to August 11th) was in the "Search for Top in TOTEM" project, a CMG project in collaboration with TOTEM, under the supervision of Martijn Mulders and Laurent Forthomme. The goal is to determine physical properties of the top anti top quark pair (tt) created by central exclusive processes, particularly the invariant mass. For that it is necessary to relate the measurements of the reconstructed top pair kinematics in the central detector of CMS with the detected protons in the Roman Pots of TOTEM just outside the interaction site, about 200 m from it. CMS only considers decay products from the proton collision, it does not regard the forward protons that participated in the collision. On the contrary, TOTEM does consider these protons. In this research measurements of both TOTEM and CMS were combined Figure 1 shows a diagram of the production of the top anti top pair from the interaction of the two protons. A central exclusive process occurs when the pr...

  10. Volcanic emissions from soils at the base of La Fossa volcano, Vulcano island, Italy

    Science.gov (United States)

    Obenholzner, J. H.; Parks, J. L.

    2006-12-01

    A top-sealed plastic tube with a diameter of ca. 15 cm had been buried vertically at the base of La Fossa volcano, Volcano island, Italy, next to the front of the obsidian flow. The tube had been filled with quartz wool to condense vapors emanating from the soil. At ca. 75 cm below the surface the sample had been exposed to vapors from Sept. 2005 to April 2006. The leached sample had not been in touch with the ground. Another glass wool cushion (ca. 3 cm thick) had been underneath to minimize capillary effects. Leaching of the quartz wool and ICP-MS analysis documented positive values for: Mg, Al, Si, P, K, Ca, Cr, Mn, Ni, Cu, Zn, Cd, Sn, Pb. Leaching with nitric acid documented also V and Fe. Acid leaching produced higher values for all elements, except K and Sn, than leaching with deionized water. Negative values had been obtained for As, Se, Mo. Influence from soil breathing can be excluded as the active fumaroles contain As and Se. This experiment documents for the first time an unknown element transport by vapors/gases through a volcanic edifice interacting with hydrothermal and magmatic gases. It remains unknown if elements detected are entering the atmosphere or are getting adsorbed onto the volcanic ash soil particles derived from reworked surge beds. This question is very important as soils might be an unknown filter medium to filter volcanically polluted air in case of major volcanic crises. Data can be obtained from the authors.

  11. The Origin of Widespread Long-lived Volcanism Across the Galapagos Volcanic Province

    Science.gov (United States)

    O'Connor, J. M.; Stoffers, P.; Wijbrans, J. R.; Worthington, T. J.

    2005-12-01

    40Ar/39Ar ages for rocks dredged (SO144 PAGANINI expedition) and drilled (DSDP) from the Galapagos Volcanic Province (Cocos, Carnegie, Coiba and Malpelo aseismic ridges and associated seamounts) show evidence of 1) increasing age with distance from the Galapagos Archipelago, 2) long-lived episodic volcanism at many locations, and 3) broad overlapping regions of coeval volcanism. The widespread nature of synchronous volcanism across the Galapagos Volcanic Province (GVP) suggests a correspondingly large Galapagos hotspot melting anomaly (O'Connor et al., 2004). Development of the GVP via Cocos and Nazca plate migration and divergence over this broad melting anomaly would explain continued multiple phases of volcanism over millions of years following the initial onset of hotspot volcanism. The question arising from these observations is whether long-lived GVP episodic volcanism is equivalent to `rejuvenescent' or a `post-erosional' phase of volcanism that occurs hundreds of thousands or million years after the main shield-building phase documented on many mid-plate seamount chains, most notably along the Hawaiian-Emperor Seamount Chain? Thus, investigating the process responsible for long-lived episodic GVP volcanism provides the opportunity to evaluate this little understood process of rejuvenation in a physical setting very different to the Hawaiian-Emperor Chain (i.e. on/near spreading axis versus mid-plate). We consider here timing and geochemical information to test the various geodynamic models proposed to explain the origin of GVP hotspot volcanism, especially the possibility of rejuvenated phases that erupt long after initial shield-building.

  12. Volcanism on differentiated asteroids (Invited)

    Science.gov (United States)

    Wilson, L.

    2013-12-01

    after passing through optically dense fire fountains. At low eruption rates and high volatile contents many clasts cooled to form spatter or cinder deposits, but at high eruption rates and low volatile contents most clasts landed hot and coalesced into lava ponds to feed lava flows. Lava flow thickness varies with surface slope, acceleration due to gravity, and lava yield strength induced by cooling. Low gravity on asteroids caused flows to be relatively thick which reduced the effects of cooling, and many flows probably attained lengths of tens of km and stopped as a result of cessation of magma supply from the reservoir rather than cooling. On most asteroids larger than 100 km radius experiencing more than ~30% mantle melting, the erupted volcanic deposits will have buried the original chondritic surface layers of the asteroid to such great depths that they were melted, or at least heavily thermally metamorphosed, leaving no present-day meteoritical evidence of their prior existence. Tidal stresses from close encounters between asteroids and proto-planets may have very briefly increased melting and melt migration speeds in asteroid interiors but only gross structural disruption would have greatly have changed volcanic histories.

  13. Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia

    2014-05-01

    In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

  14. The theory of the top

    CERN Document Server

    Klein, Felix; Nagem, Raymond J; Sandri, Guido

    The Theory of the Top. Volume IV. Technical Applications of the Theory of the Top is the fourth and final volume in a series of self-contained English translations of the classic and definitive treatment of rigid body motion. Key features: * Complete and unabridged presentation with recent advances and additional notes; * Annotations by the translators provide insights into the nature of science and mathematics in the late 19th century; * Each volume interweaves theory and applications. The Theory of the Top was originally presented by Felix Klein as an 1895 lecture at Göttingen University that was broadened in scope and clarified as a result of collaboration with Arnold Sommerfeld.  Graduate students and researchers interested in theoretical and applied mechanics will find this series of books a thorough and insightful account.  Other volumes in the series include Introduction to the Kinematics and Kinetics of the Top, Development of the Theory in the Case of the Heavy Symmetric Top, and Perturbation...

  15. Kinematic top analyses at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Grassmann, H.; CDF Collaboration

    1995-03-01

    We present an update of the top quark analysis using kinematic techniques in p{bar p} collisions at {radical}s = 1.8 TeV with the Collider Detector at Fermilab (CDF). We reported before on a study which used 19.3 pb{sup {minus}1} of data from the 1992--1993 collider run, but now we use a larger data sample of 67 pb{sup {minus}1}. First, we analyze the total transverse energy of the hard collision in W+{ge}3 jet events, showing the likely presence of a t{bar t} component in the event sample. Next, we compare in more detail the kinematic structure of W+ {ge}3 jet events with expectations for top pair production and with background processes, predominantly direct W+ jet production. We again find W+ {ge} 3 jet events which cannot be explained in terms of background, but show kinematic features as expected from top. These events also show evidence for beauty quarks, in agreement with expectations from top, but not compatible with expectations from backgrounds. The findings confirm the observation of top events made earlier in the data of the 1992--1993 collider run.

  16. The Isopach Mapping of Volcanic Deposits of Mount Samalas 1257 AD Based on the Values of Resistivity and Physical Properties

    Directory of Open Access Journals (Sweden)

    Hiden Hiden

    2017-08-01

    Full Text Available A detailed study had been conducted on the sediment of Mount Samalas’ volcanic eruption in 1257 AD. Using the framework of the reconstruction of the ancient eruption of Mount Samalas, the first step was to map and analyze the deposits of volcanic sediment. Secondly, we analyzed the effect of geomorphology and the distance function to the isopach thickness. The results show that a combination of methods allowed to provide a high resolution map of the distribution of the thickness of the volcanic deposits, both on the slope and in alluvial areas. Geo-electric survey results (both Vertical Electric Sound (VES and 2D mapping show consistent changes in the pattern of contrast resistivity layer interface, for all areas. The pattern changes in a row of the top layer, the high resistivity turned into the low. Furthermore, the second and third layer interface changes from low to the high resistivity. High resistivity on the top layer is interpreted as a layer of unconsolidated volcanic sediment. High resistivity values are range from 736 to 2000 Ohm.m on the top layer in the area of the slopes while in the area of alluvial, the resistivity values range from 20 to 958 Ohm.m. Generally, the volcanic deposits in the area of the slopes have a higher value of isopach (>17 m than in areas of alluvial (<25 m. The geomorphology seemed to have no significant effect on the isopach value, particularly pyroclastic fallout. Such is the case with distance from the source to the site, which is not linear. The value of isopach increases westward from 21 to 31 km, in contrast to the East, which began to occur at a distance of 14 km to 21 km.

  17. Indirect Climatic Effects of Major Volcanic Eruptions

    Science.gov (United States)

    Hofmann, D. J.

    2007-05-01

    The direct effects on climate, related to atmospheric emissions to the atmosphere following major volcanic eruptions, are well-known although the sparseness of such eruptions make detailed study on the range of such variations difficult. In general terms, infrared absorption by volcanic emissions to the stratosphere result in local heating early in the event when gaseous sulfur compounds exist. This early period is followed by gas to particle conversion, on a time scale of 1-2 months, promoting the formation of sulfuric acid-water droplets. Coagulation and droplet growth result in the "volcanic stratospheric aerosol layer" which is related to the predominant direct climatic effect of large eruptions, the cooling of the troposphere by backscattering of solar visible radiation to space with a recovery time scale of 1-2 years. In this paper we will discuss some of the less-known "indirect" effects of the volcanic stratospheric aerosol on climate. We label them indirect as they act on climate through intermediary atmospheric constituents. The intermediaries in the volcanic indirect climatic effect are generally atmospheric greenhouse gases or other atmospheric gases and conditions which affect greenhouse gases. For example, cooling of the troposphere following major eruptions reduces the growth rate of atmospheric carbon dioxide related to respiration by the terrestrial biosphere. In addition, redirection of part of the direct solar beam into diffuse radiation by the volcanic stratospheric aerosol stimulates plant photosynthesis, further reducing the carbon dioxide growth rate. The growth rate of the second-most important atmospheric greenhouse gas, methane, is also affected by volcanic emissions. Volcanic stratospheric aerosol particles provide surface area which catalyzes heterogeneous chemical reactions thus stimulating removal of stratospheric ozone, also a greenhouse gas. Although major droughts usually related to ENSO events have opposite effects on carbon

  18. Ages of plains volcanism on Mars

    Science.gov (United States)

    Hauber, Ernst; Jagert, Felix; Broz, Petr

    2010-05-01

    Plain-style volcanism [1] is widespread in the Tharsis and Elysium volcanic provinces on Mars, [2,3]. Detailed images and topographic data reveal the morphology and topography of clusters of low shields and associated lava flows. The landforms of plains volcanism on Mars have all well-known terrestrial analogues in basaltic volcanic regions, such as Hawaii, Iceland, and in particular the Snake River Plains [4]. The very gentle flank slopes (J. (1981) Icarus, 45, 586-601. [3] Hodges C.A. and Moore H.J. (1994) Atlas of volcanic features on Mars: USGS Prof. Paper 1534, 194 p. [4] Hauber E. et al. (2009) J. Volcanol. Geotherm. Res. 185, 69-95. [5] Wilson L. et al. (2009) J. Volcanol. Geotherm. Res. 185, 28-46. [6] Vaucher, J. et al. (2009) Icarus 204, 418-442. [7] Baratoux D. et al. (2009) J. Volcanol. Geotherm. Res. 185, 47-68. [8] Bleacher J.E. et al. (2009) J. Volcanol. Geotherm. Res. 185, 96-102. [9] Ivanov B.A. (2001) Space Sci. Rev. 96, 87-104. [10] Hartmann W.H. and Neukum G. (2001) Space Sci. Rev. 96, 165-194 [11] Kneissl T. et al. (2010) LPS XVI, submitted. [12] Michael, G.G. and Neukum G. (2010) Earth Planet. Sci. Lett., in press. . [13] Malin M.C. et al. (2007) JGR 112, E05S04, doi: 10.1029/2006JE002808.

  19. WordPress Top Plugins

    CERN Document Server

    Corbin, Brandon

    2010-01-01

    Time flies when you're having fun. This is the right way to describe this WordPress Top Plugins book by Brandon Corbin. With real world examples and by showing you the perks of having these plugins installed on your websites, the author is all set to captivate your interest from start to end. Regardless of whether this is your first time working with WordPress, or you're a seasoned WordPress coding ninja, WordPress Top Plugins will walk you through finding and installing the best plugins for generating and sharing content, building communities and reader base, and generating real advertising r

  20. National volcanic ash operations plan for aviation

    Science.gov (United States)

    ,; ,

    2007-01-01

    The National Aviation Weather Program Strategic Plan (1997) and the National Aviation Weather Initiatives (1999) both identified volcanic ash as a high-priority informational need to aviation services. The risk to aviation from airborne volcanic ash is known and includes degraded engine performance (including flameout), loss of visibility, failure of critical navigational and operational instruments, and, in the worse case, loss of life. The immediate costs for aircraft encountering a dense plume are potentially major—damages up to $80 million have occurred to a single aircraft. Aircraft encountering less dense volcanic ash clouds can incur longer-term costs due to increased maintenance of engines and external surfaces. The overall goal, as stated in the Initiatives, is to eliminate encounters with ash that could degrade the in-flight safety of aircrews and passengers and cause damage to the aircraft. This goal can be accomplished by improving the ability to detect, track, and forecast hazardous ash clouds and to provide adequate warnings to the aviation community on the present and future location of the cloud. To reach this goal, the National Aviation Weather Program established three objectives: (1) prevention of accidental encounters with hazardous clouds; (2) reduction of air traffic delays, diversions, or evasive actions when hazardous clouds are present; and (3) the development of a single, worldwide standard for exchange of information on airborne hazardous materials. To that end, over the last several years, based on numerous documents (including an OFCMsponsored comprehensive study on aviation training and an update of Aviation Weather Programs/Projects), user forums, and two International Conferences on Volcanic Ash and Aviation Safety (1992 and 2004), the Working Group for Volcanic Ash (WG/VA), under the OFCM-sponsored Committee for Aviation Services and Research, developed the National Volcanic Ash Operations Plan for Aviation and Support of the

  1. Venus - Volcanic features in Atla Region

    Science.gov (United States)

    1991-01-01

    This Magellan image from the Atla region of Venus shows several types of volcanic features and superimposed surface fractures. The area in the image is approximately 350 kilometers (217 miles) across, centered at 9 degrees south latitude, 199 degrees east longitude. Lava flows emanating from circular pits or linear fissures form flower-shaped patterns in several areas. A collapse depression approximately 20 kilometers by 10 kilometers (12 by 6 miles) near the center of the image is drained by a lava channel approximately 40 kilometers (25 miles) long. Numerous surface fractures and graben (linear valleys) criss-cross the volcanic deposits in north to northeast trends. The fractures are not buried by the lavas, indicating that the tectonic activity post-dates most of the volcanic activity.

  2. Ozone depletion following future volcanic eruptions

    Science.gov (United States)

    Eric Klobas, J.; Wilmouth, David M.; Weisenstein, Debra K.; Anderson, James G.; Salawitch, Ross J.

    2017-07-01

    While explosive volcanic eruptions cause ozone loss in the current atmosphere due to an enhancement in the availability of reactive chlorine following the stratospheric injection of sulfur, future eruptions are expected to increase total column ozone as halogen loading approaches preindustrial levels. The timing of this shift in the impact of major volcanic eruptions on the thickness of the ozone layer is poorly known. Modeling four possible climate futures, we show that scenarios with the smallest increase in greenhouse gas concentrations lead to the greatest risk to ozone from heterogeneous chemical processing following future eruptions. We also show that the presence in the stratosphere of bromine from natural, very short-lived biogenic compounds is critically important for determining whether future eruptions will lead to ozone depletion. If volcanic eruptions inject hydrogen halides into the stratosphere, an effect not considered in current ozone assessments, potentially profound reductions in column ozone would result.

  3. Geochemistry of volcanic series of Aragats province

    International Nuclear Information System (INIS)

    Meliksetyan, Kh.B.

    2012-01-01

    In this contribution we discuss geochemical and isotope characteristics of volcanism of the Aragats volcanic province and possible petrogenetical models of magma generation in collision zone of Armenian highland. We talk about combination of some specific features of collision related volcanism such as dry and high temperature conditions of magma generation, that demonstrate some similarities to intraplate-like petrogenesis and presence of mantle source enriched by earlier subductions, indicative to island-arc type magma generation models. Based on comprehensive analysis of isotope and geochemical data and some published models of magma generation beneath Aragats we lead to a petrogenetic model of origin of Aragats system to be a result of magma mixture between mantle originated mafic magma with felsic, adakite-type magmas

  4. Tropical Volcanic Soils From Flores Island, Indonesia

    Directory of Open Access Journals (Sweden)

    Hikmatullah

    2010-01-01

    Full Text Available Soils that are developed intropical region with volcanic parent materials have many unique properties, and high potential for agricultural use.The purpose of this study is to characterize the soils developed on volcanic materials from Flores Island, Indonesia,and to examine if the soils meet the requirements for andic soil properties. Selected five soils profiles developed fromandesitic volcanic materials from Flores Island were studied to determine their properties. They were compared intheir physical, chemical and mineralogical characteristics according to their parent material, and climatic characteristicdifferent. The soils were developed under humid tropical climate with ustic to udic soil moisture regimes withdifferent annual rainfall. The soils developed from volcanic ash parent materials in Flores Island showed differentproperties compared to the soils derived from volcanic tuff, even though they were developed from the sameintermediary volcanic materials. The silica contents, clay mineralogy and sand fractions, were shown as the differences.The different in climatic conditions developed similar properties such as deep solum, dark color, medium texture, andvery friable soil consistency. The soils have high organic materials, slightly acid to acid, low to medium cationexchange capacity (CEC. The soils in western region have higher clay content and showing more developed than ofthe eastern region. All the profiles meet the requirements for andic soil properties, and classified as Andisols order.The composition of sand mineral was dominated by hornblende, augite, and hypersthenes with high weatherablemineral reserves, while the clay fraction was dominated by disordered kaolinite, and hydrated halloysite. The soilswere classified into subgroup as Thaptic Hapludands, Typic Hapludands, and Dystric Haplustands

  5. Climbing back to the top

    Energy Technology Data Exchange (ETDEWEB)

    Curry, Lynn

    2010-07-01

    California - the top wind producer in the US since the 1980s lost its lead in 2008 in the face of intense competition from other states. But backed by strong financial and political support from the government, California's wind energy sector is slowly making a comeback. (orig.)

  6. Kowalevski top in quantum mechanics

    International Nuclear Information System (INIS)

    Matsuyama, A.

    2013-01-01

    The quantum mechanical Kowalevski top is studied by the direct diagonalization of the Hamiltonian. The spectra show different behaviors depending on the region divided by the bifurcation sets of the classical invariant tori. Some of these spectra are nearly degenerate due to the multiplicity of the invariant tori. The Kowalevski top has several symmetries and symmetry quantum numbers can be assigned to the eigenstates. We have also carried out the semiclassical quantization of the Kowalevski top by the EBK formulation. It is found that the semiclassical spectra are close to the exact values, thus the eigenstates can be also labeled by the integer quantum numbers. The symmetries of the system are shown to have close relations with the semiclassical quantum numbers and the near-degeneracy of the spectra. -- Highlights: •Quantum spectra of the Kowalevski top are calculated. •Semiclassical quantization is carried out by the EBK formulation. •Quantum states are labeled by the semiclassical integer quantum numbers. •Multiplicity of the classical torus makes the spectra nearly degenerate. •Symmetries, quantum numbers and near-degenerate spectra are closely related

  7. Top production at hadron colliders

    Indian Academy of Sciences (India)

    mulated by the summer of 2010, the first top quark event candidates were observed and ..... Result of combined fit to data in the exclusive three-jet bin, the exclusive .... Figure 7 shows the results of a model-independent measurement of.

  8. TEMAC, Top Event Sensitivity Analysis

    International Nuclear Information System (INIS)

    Iman, R.L.; Shortencarier, M.J.

    1988-01-01

    1 - Description of program or function: TEMAC is designed to permit the user to easily estimate risk and to perform sensitivity and uncertainty analyses with a Boolean expression such as produced by the SETS computer program. SETS produces a mathematical representation of a fault tree used to model system unavailability. In the terminology of the TEMAC program, such a mathematical representation is referred to as a top event. The analysis of risk involves the estimation of the magnitude of risk, the sensitivity of risk estimates to base event probabilities and initiating event frequencies, and the quantification of the uncertainty in the risk estimates. 2 - Method of solution: Sensitivity and uncertainty analyses associated with top events involve mathematical operations on the corresponding Boolean expression for the top event, as well as repeated evaluations of the top event in a Monte Carlo fashion. TEMAC employs a general matrix approach which provides a convenient general form for Boolean expressions, is computationally efficient, and allows large problems to be analyzed. 3 - Restrictions on the complexity of the problem - Maxima of: 4000 cut sets, 500 events, 500 values in a Monte Carlo sample, 16 characters in an event name. These restrictions are implemented through the FORTRAN 77 PARAMATER statement

  9. Top mass measurement at CDF

    International Nuclear Information System (INIS)

    Rolli, S.

    1996-06-01

    We present the measurement of the top quark mass using L = 110 pb -1 data sample of pp collisions at √s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). We show the results for the different channels and discuss with some emphasis the determination of the systematic uncertainties. 7 refs., 10 figs., 5 tabs

  10. Observation of the Top Quark

    Science.gov (United States)

    Kim, S. B.

    1995-08-01

    Top quark production is observed in{bar p}p collisions at{radical}s= 1.8 TeV at the Fermilab Tevatron. The Collider Detector at Fermilab (CDF) and D{O} observe signals consistent with t{bar t} to WWb{bar b}, but inconsistent with the background prediction by 4.8{sigma} (CDF), 4.6a (D{O}). Additional evidence for the top quark Is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top quark decay. They measure the top quark mass to be 176{plus_minus}8(stat.){plus_minus}10(sys.) GeV/c{sup 2} (CDF), 199{sub -21}{sup+19}(stat.){plus_minus}22(sys.) GeV/c{sup 2} (D{O}), and the t{bar t} production cross section to be 6.8{sub -2.4}{sup+3.6}pb (CDF), 6.4{plus_minus}2.2 pb (D{O}).

  11. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2013-01-01

    We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  12. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  13. Top Jets at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, L.G.; Lee, S.J.; Perez, G.; Sung, I.; Virzi, J.

    2008-10-06

    We investigatethe reconstruction of high pT hadronically-decaying top quarksat the Large Hadron Collider. One of the main challenges in identifying energetictop quarks is that the decay products become increasingly collimated. This reducesthe efficacy of conventional reconstruction methods that exploit the topology of thetop quark decay chain. We focus on the cases where the decay products of the topquark are reconstructed as a single jet, a"top-jet." The most basic"top-tag" methodbased on jet mass measurement is considered in detail. To analyze the feasibility ofthe top-tagging method, both theoretical and experimental aspects of the large QCDjet background contribution are examined. Based on a factorization approach, wederive a simple analytic approximation for the shape of the QCD jet mass spectrum.We observe very good agreement with the Monte Carlo simulation. We consider high pT tt bar production in the Standard Model as an example, and show that our theoretical QCD jet mass distributions can efficiently characterize the background via sideband analyses. We show that with 25 fb-1 of data, our approach allows us to resolve top-jets with pT _> 1 TeV, from the QCD background, and about 1.5 TeV top-jets with 100 fb-1, without relying on b-tagging. To further improve the significancewe consider jet shapes (recently analyzed in 0807.0234 [hep-ph]), which resolve thesubstructure of energy flow inside cone jets. A method of measuring the top quarkpolarization by using the transverse momentum of the bottom quark is also presented.The main advantages of our approach are: (i) the mass distributions are driven byfirst principle calculations, instead of relying solely on Monte Carlo simulation; (ii) for high pT jets (pT _> 1 TeV), IR-safe jet shape variables are robust against detectorresolution effects. Our analysis can be applied to other boosted massive particlessuch as the electroweak gauge bosons and the Higgs.

  14. Tellurium in active volcanic environments: Preliminary results

    Science.gov (United States)

    Milazzo, Silvia; Calabrese, Sergio; D'Alessandro, Walter; Brusca, Lorenzo; Bellomo, Sergio; Parello, Francesco

    2014-05-01

    Tellurium is a toxic metalloid and, according to the Goldschmidt classification, a chalcophile element. In the last years its commercial importance has considerably increased because of its wide use in solar cells, thermoelectric and electronic devices of the last generation. Despite such large use, scientific knowledge about volcanogenic tellurium is very poor. Few previous authors report result of tellurium concentrations in volcanic plume, among with other trace metals. They recognize this element as volatile, concluding that volcanic gases and sulfur deposits are usually enriched with tellurium. Here, we present some results on tellurium concentrations in volcanic emissions (plume, fumaroles, ash leachates) and in environmental matrices (soils and plants) affected by volcanic emissions and/or deposition. Samples were collected at Etna and Vulcano (Italy), Turrialba (Costa Rica), Miyakejima, Aso, Asama (Japan), Mutnovsky (Kamchatka) at the crater rims by using common filtration techniques for aerosols (polytetrafluoroethylene filters). Filters were both eluted with Millipore water and acid microwave digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Volcanic ashes emitted during explosive events on Etna and Copahue (Argentina) were analyzed for tellurium bulk composition and after leaching experiments to evaluate the soluble fraction of tellurium. Soils and leaves of vegetation were also sampled close to active volcanic vents (Etna, Vulcano, Nisyros, Nyiragongo, Turrialba, Gorely and Masaya) and investigated for tellurium contents. Preliminary results showed very high enrichments of tellurium in volcanic emissions comparing with other volatile elements like mercury, arsenic, thallium and bismuth. This suggests a primary transport in the volatile phase, probably in gaseous form (as also suggested by recent studies) and/or as soluble salts (halides and/or sulfates) adsorbed on the surface of particulate particles and ashes. First

  15. Volcanic air pollution hazards in Hawaii

    Science.gov (United States)

    Elias, Tamar; Sutton, A. Jeff

    2017-04-20

    Noxious sulfur dioxide gas and other air pollutants emitted from Kīlauea Volcano on the Island of Hawai‘i react with oxygen, atmospheric moisture, and sunlight to produce volcanic smog (vog) and acid rain. Vog can negatively affect human health and agriculture, and acid rain can contaminate household water supplies by leaching metals from building and plumbing materials in rooftop rainwater-catchment systems. U.S. Geological Survey scientists, along with health professionals and local government officials are working together to better understand volcanic air pollution and to enhance public awareness of this hazard.

  16. Volcanic Eruptions and Climate: Outstanding Research Issues

    Science.gov (United States)

    Robock, Alan

    2016-04-01

    Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. Based on observations after major eruptions of the past and experiments with numerical models of the climate system, we understand much about their climatic impact, but there are also a number of unanswered questions. Volcanic eruptions produce global cooling, and are an important natural cause of interannual, interdecadal, and even centennial-scale climate change. One of the most interesting volcanic effects is the "winter warming" of Northern Hemisphere continents following major tropical eruptions. During the winter in the Northern Hemisphere following every large tropical eruption of the past century, surface air temperatures over North America, Europe, and East Asia were warmer than normal, while they were colder over Greenland and the Middle East. This pattern and the coincident atmospheric circulation correspond to the positive phase of the Arctic Oscillation. While this response is observed after recent major eruptions, most state-of-the-art climate models have trouble simulating winter warming. Why? High latitude eruptions in the Northern Hemisphere, while also producing global cooling, do not have the same impact on atmospheric dynamics. Both tropical and high latitude eruptions can weaken the Indian and African summer monsoon, and the effects can be seen in past records of flow in the Nile and Niger Rivers. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade have had a small effect on global temperature trends. Some important outstanding research questions include: How much seasonal, annual, and decadal predictability is possible following a large volcanic eruption? Do

  17. Winter warming from large volcanic eruptions

    Science.gov (United States)

    Robock, Alan; Mao, Jianping

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95-percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  18. Canadian East Coast offshore petroleum industry safe lifting practices respecting offshore pedestal cranes, offshore containers, loose gear, other lifting devices, and operational best practices : standard practices

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-11-15

    This document was developed by a working group with representatives from the petroleum industry, the Offshore Petroleum Boards and Certifying Authorities. It outlines industry best practices for operators responsible for the management, planning and execution of offshore lifting operations. Its purpose is to assist in the interpretation of applicable legislation and standards. Considered within the practice are safe design requirements, manufacture, certification, testing, maintenance and inspection requirements for pedestal cranes, offshore containers, loose gear and lifting devices. Operational best practices for lifting operations are also included along with a section that identifies additional requirements for personnel lifting operations, including personnel transfers by crane and man-riding operations. 82 refs., 2 tabs., 4 figs., 3 appendices.

  19. Edge harmonic oscillations at the density pedestal in the H-mode discharges in CHS Heliotron measured using beam emission spectroscopy and magnetic probe

    Energy Technology Data Exchange (ETDEWEB)

    Kado, S. [High Temperature Plasma Center, University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8568 (Japan)]. E-mail: kado@q.t.u-tokyo.ac.jp; Oishi, T. [School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yoshinuma, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Ida, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Takeuchi, M. [Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603 (Japan); Toi, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Akiyama, T. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Minami, T. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Nagaoka, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Shimizu, A. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Okamura, S. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Tanaka, S. [School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2007-06-15

    Edge harmonic oscillations (EHO) offer the potential to relax the H-mode pedestal in a tokamak, thus avoiding edge localised modes (ELM). The mode structure of the EHO in CHS was investigated using a poloidal array of beam emission spectroscopy (BES) and a magnetic probe array. The EHO exhibited a peculiar characteristic in which the first, second and third harmonics show the same wavenumber, suggesting that the propagation velocities are different. Change in the phase of higher harmonics at the time when that of the first harmonic is zero can be described as a variation along the (m, n) = (-2, 1) mode structure, though the EHO lies on the {iota} = 1 surface. This behavior leads to an oscillation that exhibits periodic dependence of shape on spatial position.

  20. Radiation Characterization Summary: ACRR Central Cavity Free-Field Environment with the 32-Inch Pedestal at the Core Centerline (ACRR-FF-CC-32-cl).

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Richard Manuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Naranjo, Gerald E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lippert, Lance L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    This document presents the facilit y - recommended characteri zation o f the neutron, prompt gamma - ray, and delayed gamma - ray radiation fields in the Annular Core Research Reactor ( ACRR ) for the cen tral cavity free - field environment with the 32 - inch pedestal at the core centerline. The designation for this environmen t is ACRR - FF - CC - 32 - cl. The neutron, prompt gamma - ray , and delayed gamma - ray energy spectra , uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma - ray fluence profiles within the experiment area of the cavity . Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples . Acknowledgements The authors wish to th ank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work . Also thanks to David Ames for his assistance in running MCNP on the Sandia parallel machines.

  1. Measurements of Top Properties at the Tevatron

    International Nuclear Information System (INIS)

    Husemann, Ulrich; Yale U.

    2007-01-01

    The large data samples of thousands of top events collected at the Tevatron experiments CDF and D(O) allow for a variety of measurements to analyze the properties of the top quark. Guided by the question ''Is the top quark observed at the Tevatron really the top quark of the standard model,'' we present Tevatron analyses studying the top production mechanism including resonant t(bar t) production, the V -A structure of the t → Wb decay vertex, the charge of the top quark, and single-top production via flavor-changing neutral currents

  2. Evidences for a volcanic province in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.; Sudhakar, M.

    Based on various lines of evidence such as the widespread occurrence of basalts, pumice, volcanic glass shards and their transformational products (zeolites, palagonites, and smectite-rich sediments), we suggest the presence of a volcanic province...

  3. Properties of the Top Quark

    Energy Technology Data Exchange (ETDEWEB)

    Wicke, Daniel; /Wuppertal U., Dept. Math.

    2009-08-01

    The aim of particle physics is the understanding of elementary particles and their interactions. The current theory of elementary particle physics, the Standard Model, contains twelve different types of fermions which (neglecting gravity) interact through the gauge bosons of three forces. In addition a scalar particle, the Higgs boson, is needed for theoretical consistency. These few building blocks explain all experimental results found in the context of particle physics, so far. Nevertheless, it is believed that the Standard Model is only an approximation to a more complete theory. First of all the fourth known force, gravity, has withstood all attempts to be included until now. Furthermore, the Standard Model describes several features of the elementary particles like the existence of three families of fermions or the quantisation of charges, but does not explain these properties from underlying principles. Finally, the lightness of the Higgs boson needed to explain the symmetry breaking is difficult to maintain in the presence of expected corrections from gravity at high scales. This is the so called hierarchy problem. In addition astrophysical results indicate that the universe consists only to a very small fraction of matter described by the Standard Model. Large fractions of dark energy and dark matter are needed to describe the observations. Both do not have any correspondence in the Standard Model. Also the very small asymmetry between matter and anti-matter that results in the observed universe built of matter (and not of anti-matter) cannot be explained until now. It is thus an important task of experimental particle physics to test the predictions of the Standard Model to the best possible accuracy and to search for deviations pointing to necessary extensions or modifications of our current theoretical understanding. The top quark was predicted to exist by the Standard Model as the partner of the bottom quark. It was first observed in 1995 by the

  4. Properties of the Top Quark

    International Nuclear Information System (INIS)

    Wicke, Daniel

    2009-01-01

    The aim of particle physics is the understanding of elementary particles and their interactions. The current theory of elementary particle physics, the Standard Model, contains twelve different types of fermions which (neglecting gravity) interact through the gauge bosons of three forces. In addition a scalar particle, the Higgs boson, is needed for theoretical consistency. These few building blocks explain all experimental results found in the context of particle physics, so far. Nevertheless, it is believed that the Standard Model is only an approximation to a more complete theory. First of all the fourth known force, gravity, has withstood all attempts to be included until now. Furthermore, the Standard Model describes several features of the elementary particles like the existence of three families of fermions or the quantisation of charges, but does not explain these properties from underlying principles. Finally, the lightness of the Higgs boson needed to explain the symmetry breaking is difficult to maintain in the presence of expected corrections from gravity at high scales. This is the so called hierarchy problem. In addition astrophysical results indicate that the universe consists only to a very small fraction of matter described by the Standard Model. Large fractions of dark energy and dark matter are needed to describe the observations. Both do not have any correspondence in the Standard Model. Also the very small asymmetry between matter and anti-matter that results in the observed universe built of matter (and not of anti-matter) cannot be explained until now. It is thus an important task of experimental particle physics to test the predictions of the Standard Model to the best possible accuracy and to search for deviations pointing to necessary extensions or modifications of our current theoretical understanding. The top quark was predicted to exist by the Standard Model as the partner of the bottom quark. It was first observed in 1995 by the

  5. Toiduainetööstuse TOP 95 aastal 2003

    Index Scriptorium Estoniae

    2004-01-01

    Toiduainetööstuse TOP 95; Kasumi TOP 40; Käibe TOP 40; Kasumi kasvu TOP 30; Rentaabluse TOP 30; Alkoholitootjate TOP; Pagarite TOP; Käibe kasvu TOP 30; Omakapitali tootlikkuse TOP 30; Toiduainetööstuste üld- ja finantsandmed

  6. Top quark production at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Varnes, Erich W.; /Arizona U.

    2010-09-01

    The Fermilab Tevatron has, until recently, been the only accelerator with sufficient energy to produce top quarks. The CDF and D0 experiments have collected large samples of top quarks. We report on recent top quark production measurements of the single top and t{bar t} production cross sections, as well as studies of the t{bar t} invariant mass distribution and a search for highly boosted top quarks.

  7. Ground-based remote sensing of volcanic CO2 and correlated SO2, HF, HCl, and BrO, in safe-distance from the crater

    Science.gov (United States)

    Butz, Andre; Solvejg Dinger, Anna; Bobrowski, Nicole; Kostinek, Julian; Fieber, Lukas; Fischerkeller, Constanze; Giuffrida, Giovanni Bruno; Hase, Frank; Klappenbach, Friedrich; Kuhn, Jonas; Lübcke, Peter; Tirpitz, Lukas; Tu, Qiansi

    2017-04-01

    Remote sensing of CO2 enhancements in volcanic plumes can be a tool to estimate volcanic CO2 emissions and thereby, to gain insight into the geological carbon cycle and into volcano interior processes. However, remote sensing of the volcanic CO2 is challenged by the large atmospheric background concentrations masking the minute volcanic signal. Here, we report on a demonstrator study conducted in September 2015 at Mt. Etna on Sicily, where we deployed an EM27/SUN Fourier Transform Spectrometer together with a UV spectrometer on a mobile remote sensing platform. The spectrometers were operated in direct-sun viewing geometry collecting cross-sectional scans of solar absorption spectra through the volcanic plume by operating the platform in stop-and-go patterns in 5 to 10 kilometers distance from the crater region. We successfully detected correlated intra-plume enhancements of CO2 and volcanic SO2, HF, HCl, and BrO. The path-integrated volcanic CO2 enhancements amounted to about 0.5 ppm (on top of the ˜400 ppm background). Key to successful detection of volcanic CO2 was A) the simultaneous observation of the O2 total column which allowed for correcting changes in the CO2 column caused by changes in observer altitude and B) the simultaneous measurement of volcanic species co-emitted with CO2 which allowed for discriminating intra-plume and extra-plume observations. The latter were used for subtracting the atmospheric CO2 background. The field study suggests that our remote sensing observatory is a candidate technique for volcano monitoring in safe distance from the crater region.

  8. Thermal design of top shield

    International Nuclear Information System (INIS)

    Raghupathy, S.; Velusamy, K.; Parthasarathy, U.; Ghosh, D.; Selvaraj, P.; Chellapandi, P.; Chetal, S.C.

    2005-01-01

    Full text of publication follows: Prototype Fast Breeder Reactor (PFBR) is a 500 MWe, sodium cooled, pool type fast reactor. The top shield forms the top cover for the main vessel (MV) and includes roof slab (RS), large rotatable plug (LRP), small rotatable plug (SRP) and control Plug (CP). RS, LRP and SRP are box type structures consisting of top and bottom plates stiffened by radial stiffeners and vertical penetration shells. TS is exposed to argon cover gas provided above sodium pool on the bottom side and reactor containment building air at the top. Heat transfer takes place through the argon cover gas to the bottom plate of TS. Annular gaps are formed between the components supported on TS and the component penetrations through which cellular convection takes place. A single thermal shield provided below TS reduces the heat flux to the bottom plate to 1.15 kW/m 2 . The MV (SS 316 LN) is welded to RS (carbon steel A48 P2) through a dissimilar metal weld. A step in RS and an anti convection barrier (ACB) outside RS are provided to limit the temperature at the MV-RS junction. The MV is surrounded by safety vessel (SV) and reactor vault made of concrete. Thermal insulation is provided outside SV to limit the heat transfer to the reactor vault. The design requirements of TS are to maintain the operating temperature at 383-393 K, limit the temperature difference (ΔT) across the height of TS to 20 / 100 K under normal operation/loss of cooling, provide minimum annular gap size at the component penetrations, provide a nearly linear temperature gradient in the CP portion within the height of TS, maintain the temperature of top plate of CP > 383 K, limit the ΔT across the top plate of CP to 2 K, limit the temperature near the inflatable / backup seal to 393 K, limit the temperature at the MV-RS junction and the heat flux to the reactor vault. The total heat transferred to TS is estimated to be 210 kW. A dedicated closed loop cooling system with a total flow rate of 10

  9. Improving volcanic ash forecasts with ensemble-based data assimilation

    NARCIS (Netherlands)

    Fu, Guangliang

    2017-01-01

    The 2010 Eyjafjallajökull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash forecasting in recent years. For forecasting the volcanic ash transport after eruption onset, a volcanic ash transport and diffusion model (VATDM) needs to be

  10. Volcanic Characteristics of Kueishantao in Northeast Taiwan and Their Implications

    Directory of Open Access Journals (Sweden)

    Ching-Lung Chiu

    2010-01-01

    Full Text Available Kueishantao (KST is a small offshore volcanic island located at the southernmost part of the Okinawa Trough. In this study, we conducted a detailed mapping incorporating the new high resolution LiDAR DTM laser scanning device to accurately construct a volcanic sequence. A new 1/5000 geological map was established. One primary volcanic cone, composed of layers of both lava flows and pyroclastic rocks constituted the major edifice of KST. The other minor volcanic cone, which consists of volcanic lapillis and blocks, is seated to the east of the main cone. The escarped and nearly straight coast in the southern part of the KST indicates that the volcano suffered a large post-volcanic edifice collapse erasing nearly one half of the volume of both volcanic cones. The increase in the abundance of the xenoliths of sedimentary rocks from the lower to the upper part of the volcanic sequence indicates that the formation of volcanic rocks of the KST involved an intensification of crustal contamination. The possibility of volcanic eruption can not be excluded in the future based on the present thermolu¬minescene age data of 7 ka. The associated eruptive ash fall and tsunami induced by the further collapse of the KST volcanic edifice might have great influence to the adjacent inland. Thus, long-term monitoring of volcanic activities around KST should be required for future hazard assessments.

  11. Apollo 15 mare volcanism: constraints and problems

    International Nuclear Information System (INIS)

    Delano, J.W.

    1985-01-01

    The Apollo 15 landing site contains more volcanics in the form of crystalline basalts and pristine glasses, which form the framework for all models dealing with the mantle beneath that site. Major issues on the petrology of the mare source regions beneath that portion of Mare Imbrium are summarized

  12. Monogenetic volcanism: personal views and discussion

    Science.gov (United States)

    Németh, K.; Kereszturi, G.

    2015-11-01

    Monogenetic volcanism produces small-volume volcanoes with a wide range of eruptive styles, lithological features and geomorphic architectures. They are classified as spatter cones, scoria (or cinder) cones, tuff rings, maars (maar-diatremes) and tuff cones based on the magma/water ratio, dominant eruption styles and their typical surface morphotypes. The common interplay between internal, such as the physical-chemical characteristics of magma, and external parameters, such as groundwater flow, substrate characteristics or topography, plays an important role in creating small-volume volcanoes with diverse architectures, which can give the impression of complexity and of similarities to large-volume polygenetic volcanoes. In spite of this volcanic facies complexity, we defend the term "monogenetic volcano" and highlight the term's value, especially to express volcano morphotypes. This study defines a monogenetic volcano, a volcanic edifice with a small cumulative volume (typically ≤1 km3) that has been built up by one continuous, or many discontinuous, small eruptions fed from one or multiple magma batches. This definition provides a reasonable explanation of the recently recognized chemical diversities of this type of volcanism.

  13. Payenia volcanic province, southern Mendoza, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina; Holm, Paul Martin; Llambias, Eduardo Jorge

    2013-01-01

    The Pleistocene to Holocene Payenia volcanic province is a backarc region of 60,000 km2 in Mendoza, Argentina, which is dominated by transitional to alkaline basalts and trachybasalts. We present major and trace element compositions of 139 rocks from this area of which the majority are basaltic...

  14. Monitoring and forecasting Etna volcanic plumes

    Directory of Open Access Journals (Sweden)

    S. Scollo

    2009-09-01

    Full Text Available In this paper we describe the results of a project ongoing at the Istituto Nazionale di Geofisica e Vulcanologia (INGV. The objective is to develop and implement a system for monitoring and forecasting volcanic plumes of Etna. Monitoring is based at present by multispectral infrared measurements from the Spin Enhanced Visible and Infrared Imager on board the Meteosat Second Generation geosynchronous satellite, visual and thermal cameras, and three radar disdrometers able to detect ash dispersal and fallout. Forecasting is performed by using automatic procedures for: i downloading weather forecast data from meteorological mesoscale models; ii running models of tephra dispersal, iii plotting hazard maps of volcanic ash dispersal and deposition for certain scenarios and, iv publishing the results on a web-site dedicated to the Italian Civil Protection. Simulations are based on eruptive scenarios obtained by analysing field data collected after the end of recent Etna eruptions. Forecasting is, hence, supported by plume observations carried out by the monitoring system. The system was tested on some explosive events occurred during 2006 and 2007 successfully. The potentiality use of monitoring and forecasting Etna volcanic plumes, in a way to prevent threats to aviation from volcanic ash, is finally discussed.

  15. X-ray microanalysis of volcanic ash

    International Nuclear Information System (INIS)

    Kearns, S L; Buse, B

    2012-01-01

    The 2010 eruption of Eyjafjallajökull volcano in Iceland demonstrated the disruptive nature of high-level volcanic ash emissions to the world's air traffic. The chemistry of volcanic material is complex and varied. Different eruptions yield both compositional and morphological variation. Equally a single eruption, such as that in Iceland will evolve over time and may potentially produce a range of volcanic products of varying composition and morphology. This variability offers the petrologist the opportunity to derive a tracer to the origins both spatially and temporally of a single particle by means of electron microbeam analysis. EPMA of volcanic ash is now an established technique for this type of analysis as used in tephrachronology. However, airborne paniculate material may, as in the case of Eyjafjallajökull, result in a particle size that is too small and too dispersed for preparation of standard EPMA mounts. Consequently SEM-EDS techniques are preferred for this type of quantitative analysis . Results of quantitative SEM-EDS analysis yield data with a larger precision error than EPMA yet sufficient to source the original eruption. Uncoated samples analyzed using variable pressure SEM yield slightly poorer results at modest pressures.

  16. Amazonian volcanism inside Valles Marineris on Mars

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Hauber, E.; Wray, J. J.; Michael, G.

    2017-01-01

    Roč. 473, September (2017), s. 122-130 ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Mars * Valles Marineris * volcanism * scoria cone * hydrothermal activity Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology Impact factor: 4.409, year: 2016

  17. The Elusive Evidence of Volcanic Lightning.

    Science.gov (United States)

    Genareau, K; Gharghabi, P; Gafford, J; Mazzola, M

    2017-11-14

    Lightning strikes are known to morphologically alter and chemically reduce geologic formations and deposits, forming fulgurites. A similar process occurs as the result of volcanic lightning discharge, when airborne volcanic ash is transformed into lightning-induced volcanic spherules (LIVS). Here, we adapt the calculations used in previous studies of lightning-induced damage to infrastructure materials to determine the effects on pseudo-ash samples of simplified composition. Using laboratory high-current impulse experiments, this research shows that within the lightning discharge channel there is an ideal melting zone that represents roughly 10% or less of the total channel radius at which temperatures are sufficient to melt the ash, regardless of peak current. The melted ash is simultaneously expelled from the channel by the heated, expanding air, permitting particles to cool during atmospheric transport before coming to rest in ash fall deposits. The limited size of this ideal melting zone explains the low number of LIVS typically observed in volcanic ash despite the frequent occurrence of lightning during explosive eruptions.

  18. Sources of Quaternary volcanism in the Itasy and Ankaratra volcanic fields, Madagascar

    Science.gov (United States)

    Rasoazanamparany, C.; Widom, E.; Kuentz, D. C.; Raharimahefa, T.; Rakotondrazafy, F. M. A.; Rakotondravelo, K. M.

    2017-12-01

    We present new major and trace element and Sr, Nd, Pb and Os isotope data for Quaternary basaltic lavas and tephra from the Itasy and Ankaratra volcanic fields, representing the most recent volcanism in Madagascar. Mafic magmas from Itasy and Ankaratra exhibit significant inter- and intra-volcanic field geochemical heterogeneity. The Itasy eruptive products range in composition from foidite to phonotephrite whereas Ankaratra lavas range from basanite to trachybasalts. Trace element signatures of samples from both volcanic fields are very similar to those of ocean island basalts (OIB), with significant enrichment in Nb and Ta, depletion in Rb, Cs, and K, and relatively high Nb/U and Ce/Pb. However, the Itasy volcanic rocks show enrichment relative to those of Ankaratra in most incompatible elements, indicative of a more enriched source and/or lower degrees of partial melting. Significant inter- and intra-volcanic field heterogeneity is also observed in Sr, Nd, Pb and Os isotope signatures. The Itasy volcanic rocks generally have less radiogenic Sr and Nd isotopic ratios but more radiogenic Pb isotopic signatures than the Ankaratra volcanic field. Together, the Itasy and Ankaratra volcanic rocks form a well-defined negative correlation in Sr vs. Pb isotopes that could be attributed to lithospheric contamination or variable degrees of mixing between distinct mantle sources. However, the lack of correlation between isotopes and indices of crustal contamination (e.g. MgO and Nb/U) are inconsistent with shallow lithospheric contamination, and instead suggest mixing between compositionally distinct mantle sources. Furthermore, although Sr-Pb isotope systematics are apparently consistent with mixing between two different sources, distinct trends in Sr vs. Nd isotopes displayed by samples from Itasy and Ankaratra, respectively, argue for more complex source mixing involving three or more sources. The current data demonstrate that although the Itasy and Ankaratra volcanic

  19. Microphysical Properties of Alaskan Volcanic Ash

    Science.gov (United States)

    Puthukkudy, A.; Espinosa, R.; Rocha Lima, A.; Remer, L.; Colarco, P. R.; Whelley, P.; Krotkov, N. A.; Young, K.; Dubovik, O.; Wallace, K.; Martins, J. V.

    2017-12-01

    Volcanic ash has the potential to cause a variety of severe problems for human health and the environment. Therefore, effective monitoring of the dispersion and fallout from volcanic ash clouds and characterization of the aerosol particle properties are essential. One way to acquire information from volcanic clouds is through satellite remote sensing: such images have greater coverage than ground-based observations and can present a "big picture" perspective. A challenge of remote sensing is that assumptions of certain properties of the target are often a pre-requisite for making accurate and quantitative retrievals. For example, detailed information about size distribution, sphericity, and optical properties of the constituent matter is needed or must be assumed. The same kind of information is also needed for atmospheric transport models to properly simulate the dispersion and fallout of volcanic ash. Presented here is a laboratory method to determine the microphysical and optical properties of volcanic ash samples collected from two Alaskan volcanoes with markedly different compositions. Our method uses a Polarized Imaging Nephelometer (PI-Neph) and a system that re-suspends the particles in an air flow. The PI-Neph measures angular light scattering and polarization of the re-suspended particles from 3o to 175o in scattering angle, with an angular resolution of 1o . Primary measurements include phase function and polarized phase function at three wavelengths (445nm, 532nm, and 661nm). Size distribution, sphericity, and complex refractive index are retrieved indirectly from the PI-Neph measurements using the GRASP (Generalized Retrieval of Aerosol and Surface Properties) inversion algorithm. We report the results of this method applied to samples from the Mt. Okmok (2008) and Mt. Katmai (1912) volcanic eruptions. To our knowledge, this is the first time direct measurements of phase matrix elements of ash from Mt. Okmok and Mt. Katmai have been reported. Retrieved

  20. Fluids in volcanic and geothermal systems

    Science.gov (United States)

    Sigvaldason, Gudmundur E.

    Mineral buffers control the composition of most volatile components of magmas and dissolved species in geothermal fluids. The only element which occurs in significant quantities in volcanic and geothermal fluids and is not controlled by mineral buffers is chlorine. It is argued that in absence of marine influence, geothermal fluids reflect the chlorine content of associated magmatic fluids. The chlorine content of oceanic volcanic rocks has a positive correlation with elements, which are believed to indicate a heterogenous source region. Since the source is generally believed to be the Earth's mantle, the implication is that the mantle is heterogenous with regard to chlorine and other volatiles. Such heterogeneities would have important consequences for genesis and distribution of ore. All major magma types of the oceanic environment occur in Iceland. Their spatial distribution is closely related to a volcanotectonic pattern, suggesting crustal control. A geophysical model of crustal accretion in a rift zone is used in conjunction with classical petrology to predict geochemical processes in a rift zone crust. The model has two kinematic parameters-drift rate and subsidence rate-which combined describe trajectories of mass particles deposited on the surface. When considering in conjunction with thermal gradients of the rift zone a series of metamorphic reactions and chemical fractionation processes are bound to occur, eventually resulting in a layering of the oceanic crust. The physical parameters result in a derived variable, rift zone residence time, which depends on the width of a rift zone. Long residence times in a wide rift zone lead to multistage recycling of material. Other properties of the model, based on geometric arrangement of productive fissure swarms within a rift zone, explain off-rift volcanism as directly related to rift zone processes, either as plate trapped magmatic domains or a transgressive thermal anomaly into an older crust. Off

  1. Pacific seamount volcanism in space and time

    Science.gov (United States)

    Hillier, J. K.

    2007-02-01

    Seamounts constitute some of the most direct evidence about intraplate volcanism. As such, when seamounts formed and into which tectonic setting they erupted (i.e. on-ridge or off-ridge) are a useful reflection of how the properties of the lithosphere interact with magma generation in the fluid mantle beneath. Proportionately few seamounts are radiometrically dated however, and these tend to be recently active. In order to more representatively sample and better understand Pacific seamount volcanism this paper estimates the eruption ages (tvolc) of 2706 volcanoes via automated estimates of lithospheric strength. Lithospheric strength (GTRrel) is deduced from the ratio of gravity to topography above the summits of volcanoes, and is shown to correlate with seafloor age at the time of volcanic loading (Δt) at 61 sites where radiometric constraints upon Δt exist. A trend of fits data for these 61, and with seafloor age (tsf) known, can date the 2706 volcanoes; tvolc = tsf - Δt. Widespread recurrences of volcanism proximal to older features (e.g. the Cook-Austral alignment in French Polynesia) suggest that the lithosphere exerts a significant element of control upon the location of volcanism, and that magmatic throughput leaves the lithosphere more susceptible to the passage of future melts. Observations also prompt speculation that: the Tavara seamounts share morphological characteristics and isostatic compensation state with the Musicians, and probably formed similarly; the Easter Island chain may be a modern analogy to the Cross-Lines; a Musicians - South Hawaiian seamounts alignment may be deflecting the Hawaiian hotspot trace.

  2. Cooling Rates of Lunar Volcanic Glass Beads

    Science.gov (United States)

    Hui, Hejiu; Hess, Kai-Uwe; Zhang, Youxue; Peslier, Anne; Lange, Rebecca; Dingwell, Donald; Neal, Clive

    2016-01-01

    It is widely accepted that the Apollo 15 green and Apollo 17 orange glass beads are of volcanic origin. The diffusion profiles of volatiles in these glass beads are believed to be due to degassing during eruption (Saal et al., 2008). The degree of degassing depends on the initial temperature and cooling rate. Therefore, the estimations of volatiles in parental magmas of lunar pyroclastic deposits depend on melt cooling rates. Furthermore, lunar glass beads may have cooled in volcanic environments on the moon. Therefore, the cooling rates may be used to assess the atmospheric condition in an early moon, when volcanic activities were common. The cooling rates of glasses can be inferred from direct heat capacity measurements on the glasses themselves (Wilding et al., 1995, 1996a,b). This method does not require knowledge of glass cooling environments and has been applied to calculate the cooling rates of natural silicate glasses formed in different terrestrial environments. We have carried out heat capacity measurements on hand-picked lunar glass beads using a Netzsch DSC 404C Pegasus differential scanning calorimeter at University of Munich. Our preliminary results suggest that the cooling rate of Apollo 17 orange glass beads may be 12 K/min, based on the correlation between temperature of the heat capacity curve peak in the glass transition range and glass cooling rate. The results imply that the parental magmas of lunar pyroclastic deposits may have contained more water initially than the early estimations (Saal et al., 2008), which used higher cooling rates, 60-180 K/min in the modeling. Furthermore, lunar volcanic glass beads could have been cooled in a hot gaseous medium released from volcanic eruptions, not during free flight. Therefore, our results may shed light on atmospheric condition in an early moon.

  3. The Online GVP/USGS Weekly Volcanic Activity Report: Providing Timely Information About Worldwide Volcanism

    Science.gov (United States)

    Mayberry, G. C.; Guffanti, M. C.; Luhr, J. F.; Venzke, E. A.; Wunderman, R. L.

    2001-12-01

    The awesome power and intricate inner workings of volcanoes have made them a popular subject with scientists and the general public alike. About 1500 known volcanoes have been active on Earth during the Holocene, approximately 50 of which erupt per year. With so much activity occurring around the world, often in remote locations, it can be difficult to find up-to-date information about current volcanism from a reliable source. To satisfy the desire for timely volcano-related information the Smithsonian Institution and US Geological Survey combined their strengths to create the Weekly Volcanic Activity Report. The Smithsonian's Global Volcanism Program (GVP) has developed a network of correspondents while reporting worldwide volcanism for over 30 years in their monthly Bulletin of the Global Volcanism Network. The US Geological Survey's Volcano Hazards Program studies and monitors volcanoes in the United States and responds (upon invitation) to selected volcanic crises in other countries. The Weekly Volcanic Activity Report is one of the most popular sites on both organization's websites. The core of the Weekly Volcanic Activity Report is the brief summaries of current volcanic activity around the world. In addition to discussing various types of volcanism, the summaries also describe precursory activity (e.g. volcanic seismicity, deformation, and gas emissions), secondary activity (e.g. debris flows, mass wasting, and rockfalls), volcanic ash hazards to aviation, and preventative measures. The summaries are supplemented by links to definitions of technical terms found in the USGS photoglossary of volcano terms, links to information sources, and background information about reported volcanoes. The site also includes maps that highlight the location of reported volcanoes, an archive of weekly reports sorted by volcano and date, and links to commonly used acronyms. Since the Weekly Volcanic Activity Report's inception in November 2000, activity has been reported at

  4. Top quark studies at hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sinervo, P.K. [Univ. of Toronto, Ontario (Canada)

    1997-01-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.

  5. Top quark studies at hadron colliders

    International Nuclear Information System (INIS)

    Sinervo, P.K.

    1997-01-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented

  6. Top quark studies at hadron colliders

    International Nuclear Information System (INIS)

    Sinervo, P.K.

    1996-08-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and D null collaborations are reviewed, including the top quark cross section, mass, branching fractions and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented

  7. Fluid volcanism on Miranda and Ariel - Flow morphology and composition

    Science.gov (United States)

    Schenk, Paul M.

    1991-01-01

    Several types of volcanic units have been recognized on the icy Uranian satellites Miranda and Ariel. On Miranda, ridges characterized by crest grooves are up to 10 km wide and 500 m high. A continuous flat-topped flow band also 10 km wide and 500 m high forms the outer southern margin of Elsinore Corona, which appears to comprise coalesced flow bands and ridges. On Ariel, in addition to at least one ridge unit similar to those on Miranda, flood plains material has covered the floors of deep chasmata (grabens) and an irregular depression. Flows on both satellites are characterized by linear vent geometries and distinct topographic margins, which indicate extrusion of a relatively viscous material. The topography of the flows can be used to estimate flow viscosity or yield strength using a Bingham plastic model. Extrusion viscosity estimates, incorporating plausible volcanologically based emplacement time scales and a rigid crust correction, range from 10 MP to 1 GP (10 TP in the unlikely absence of a chilled crust). Viscosity estimates are dependent on the assumed emplacement time scale, however, and could be as high as 10 PP, if a solid-state-based time scale is assumed.

  8. The Ngorongoro Volcanic Highland and its relationships to volcanic deposits at Olduvai Gorge and East African Rift volcanism.

    Science.gov (United States)

    Mollel, Godwin F; Swisher, Carl C

    2012-08-01

    The Ngorongoro Volcanic Highland (NVH), situated adjacent and to the east of Olduvai Gorge in northern Tanzania, is the source of the immense quantities of lava, ignimbrite, air fall ash, and volcaniclastic debris that occur interbedded in the Plio-Pleistocene sedimentary deposits in the Laetoli and Olduvai areas. These volcanics have proven crucial to unraveling stratigraphic correlations, the age of these successions, the archaeological and paleontological remains, as well as the source materials from which the bulk of the stone tools were manufactured. The NVH towers some 2,000 m above the Olduvai and Laetoli landscapes, affecting local climate, run-off, and providing varying elevation - climate controlled ecosystem, habitats, and riparian corridors extending into the Olduvai and Laetoli lowlands. The NVH also plays a crucial role in addressing the genesis and history of East African Rift (EAR) magmatism in northern Tanzania. In this contribution, we provide age and petrochemical compositions of the major NVH centers: Lemagurut, basalt to benmorite, 2.4-2.2 Ma; Satiman, tephrite to phonolite, 4.6-3.5 Ma; Oldeani, basalt to trachyandesite, 1.6-1.5 Ma; Ngorongoro, basalt to rhyolite, 2.3-2.0 Ma; Olmoti, basalt to trachyte, 2.0-1.8 Ma; Embagai, nephelinite to phonolite, 1.2-0.6 Ma; and Engelosin, phonolite, 3-2.7 Ma. We then discuss how these correlate in time and composition with volcanics preserved at Olduvai Gorge. Finally, we place this into context with our current understanding as to the eruptive history of the NVH and relationship to East African Rift volcanism. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Toiduainetööstuse TOP 95 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Toiduainetööstuse TOP 95. Käibe TOP 50. Kasumi TOP 50. Rentaabluse TOP 25. Kasumi kasvu TOP 25. Omakapitali tootlikkuse TOP 25. Käibe kasvu TOP 25. Toiduainetööstuse TOP 95 ettevõtted 2002: üldandmed ja finantsandmed

  10. Ida-Virumaa ettevõtete TOP aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Ettevõtete TOP 55. TOP-i esikümme. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Ida-Virumaa firmade üldandmed. Ida-Virumaa firmade finantsandmed

  11. Conceptual model of volcanism and volcanic hazards of the region of Ararat valley, Armenia

    Science.gov (United States)

    Meliksetian, Khachatur; Connor, Charles; Savov, Ivan; Connor, Laura; Navasardyan, Gevorg; Manucharyan, Davit; Ghukasyan, Yura; Gevorgyan, Hripsime

    2015-04-01

    Armenia and the adjacent volcanically active regions in Iran, Turkey and Georgia are located in the collision zone between the Arabian and Eurasian lithospheric plates. The majority of studies of regional collision related volcanism use the model proposed by Keskin, (2003) where volcanism is driven by Neo-Tethyan slab break-off. In Armenia, >500 Quaternary-Holocene volcanoes from the Gegham, Vardenis and Syunik volcanic fields are hosted within pull-apart structures formed by active faults and their segments (Karakhanyan et al., 2002), while tectonic position of the large in volume basalt-dacite Aragats volcano and periphery volcanic plateaus is different and its position away from major fault lines necessitates more complex volcano-tectonic setup. Our detailed volcanological, petrological and geochemical studies provide insight into the nature of such volcanic activity in the region of Ararat Valley. Most magmas, such as those erupted in Armenia are volatile-poor and erupt fairly hot. Here we report newly discovered tephra sequences in Ararat valley, that were erupted from historically active Ararat stratovolcano and provide evidence for explosive eruption of young, mid K2O calc-alkaline and volatile-rich (>4.6 wt% H2O; amph-bearing) magmas. Such young eruptions, in addition to the ignimbrite and lava flow hazards from Gegham and Aragats, present a threat to the >1.4 million people (~ ½ of the population of Armenia). We will report numerical simulations of potential volcanic hazards for the region of Ararat valley near Yerevan that will include including tephra fallout, lava flows and opening of new vents. Connor et al. (2012) J. Applied Volcanology 1:3, 1-19; Karakhanian et al. (2002), JVGR, 113, 319-344; Keskin, M. (2003) Geophys. Res. Lett. 30, 24, 8046.

  12. Volcanic Gases and Hot Spring Water to Evaluate the Volcanic Activity of the Mt. Baekdusan

    Science.gov (United States)

    Yun, S. H.; Lee, S.; Chang, C.

    2017-12-01

    This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu, also known as Changbaishan on the North Korea(DPRK)-China border, during the period from July 2015 to August 2016. Also, we confirmed the errors that HCO3- concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved CO2 in hot spring waters was analyzed using gas chromatograph in Lee et al.(2014). Improving this, from 2015, we used TOC-IC to analysis dissolved CO2. Also, we analyzed the Na2CO3 standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of the Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the HCO3-concentrations of 2014 samples. During the period of study, CO2/CH4 ratios in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction condition, and carbon in volcanic gases become more favorable to distribute into CH4 or CO than CO2. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of CO2which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cations, and some trace elements (As, Cd, Re).This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMIPA 2015-3060.

  13. [Effects of volcanic eruptions on human health in Iceland. Review].

    Science.gov (United States)

    Gudmundsson, Gunnar; Larsen, Guðrun

    2016-01-01

    Volcanic eruptions are common in Iceland and have caused health problems ever since the settlement of Iceland. Here we describe volcanic activity and the effects of volcanic gases and ash on human health in Iceland. Volcanic gases expelled during eruptions can be highly toxic for humans if their concentrations are high, irritating the mucus membranes of the eyes and upper respiratory tract at lower concentrations. They can also be very irritating to the skin. Volcanic ash is also irritating for the mucus membranes of the eyes and upper respiratory tract. The smalles particles of volcanic ash can reach the alveoli of the lungs. Described are four examples of volcanic eruptions that have affected the health of Icelanders. The eruption of Laki volcanic fissure in 1783-1784 is the volcanic eruption that has caused the highest mortality and had the greatest effects on the well-being of Icelanders. Despite multiple volcanic eruptions during the last decades in Iceland mortality has been low and effects on human health have been limited, although studies on longterm effects are lacking. Studies on the effects of the Eyjafjallajökul eruption in 2010 on human health showed increased physical and mental symptoms, especially in those having respiratory disorders. The Directorate of Health in Iceland and other services have responded promptly to recurrent volcanic eruptions over the last few years and given detailed instructions on how to minimize the effects on the public health. Key words: volcanic eruptions, Iceland, volcanic ash, volcanic gases, health effects, mortality. Correspondence: Gunnar Guðmundsson, ggudmund@landspitali.is.

  14. Table-top job analysis

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-01

    The purpose of this Handbook is to establish general training program guidelines for training personnel in developing training for operation, maintenance, and technical support personnel at Department of Energy (DOE) nuclear facilities. TTJA is not the only method of job analysis; however, when conducted properly TTJA can be cost effective, efficient, and self-validating, and represents an effective method of defining job requirements. The table-top job analysis is suggested in the DOE Training Accreditation Program manuals as an acceptable alternative to traditional methods of analyzing job requirements. DOE 5480-20A strongly endorses and recommends it as the preferred method for analyzing jobs for positions addressed by the Order.

  15. Top-down cellular pyramids

    Energy Technology Data Exchange (ETDEWEB)

    Wu, A Y; Rosenfeld, A

    1983-10-01

    A cellular pyramid is an exponentially tapering stack of arrays of processors (cells), where each cell is connected to its neighbors (siblings) on its own level, to a parent on the level above, and to its children on the level below. It is shown that in some situations, if information flows top-down only, from fathers to sons, then a cellular pyramid may be no faster than a one-level cellular array; but it may be possible to use simpler cells in the pyramid case. 23 references.

  16. Top quark production at the LHC

    CERN Document Server

    Gilles, Geoffrey; The ATLAS collaboration

    2018-01-01

    The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections, including differential distributions and production in association with bosons, will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass are also presented.

  17. Results on top-quark physics and top-quark-like signatures by CMS

    Science.gov (United States)

    Chabert, Eric; CMS Collaboration

    2017-07-01

    This report reviews the results obtained by the CMS Collaboration on top quark physics, focusing on the latest ones based on p-p collisions provided by the LHC at \\sqrt{s}=13{{TeV}} during Run II. It covers measurements of single-top, top quark pairs and associated productions as well as measurements of top quark properties. Finally several beyond the standard model searches involving top quark in the final states are presented, such as searches for supersymmetry in the third generation, heavy resonances decaying into a top quark pair, or dark matter produced in association to a single-top or a top quark pair.

  18. Obsidian hydration dating of volcanic events

    Science.gov (United States)

    Friedman, I.; Obradovich, J.

    1981-01-01

    Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and KAr methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper. ?? 1981.

  19. Volcanic Origin of Alkali Halides on Io

    Science.gov (United States)

    Schaefer, L.; Fegley, B., Jr.

    2003-01-01

    The recent observation of NaCl (gas) on Io confirms our earlier prediction that NaCl is produced volcanically. Here we extend our calculations by modeling thermochemical equilibrium of O, S, Li, Na, K, Rb, Cs, F, Cl, Br, and I as a function of temperature and pressure in a Pele-like volcanic gas with O/S/Na/Cl/K = 1.518/1/0.05/0.04/0.005 and CI chondritic ratios of the other (as yet unobserved) alkalis and halogens. For reference, the nominal temperature and pressure for Pele is 1760 plus or minus 210 K and 0.01 bars based on Galileo data and modeling.

  20. Volcanic ash impacts on critical infrastructure

    Science.gov (United States)

    Wilson, Thomas M.; Stewart, Carol; Sword-Daniels, Victoria; Leonard, Graham S.; Johnston, David M.; Cole, Jim W.; Wardman, Johnny; Wilson, Grant; Barnard, Scott T.

    2012-01-01

    Volcanic eruptions can produce a wide range of hazards. Although phenomena such as pyroclastic flows and surges, sector collapses, lahars and ballistic blocks are the most destructive and dangerous, volcanic ash is by far the most widely distributed eruption product. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to significant societal impacts. Even relatively small eruptions can cause widespread disruption, damage and economic loss. Volcanic eruptions are, in general, infrequent and somewhat exotic occurrences, and consequently in many parts of the world, the management of critical infrastructure during volcanic crises can be improved with greater knowledge of the likely impacts. This article presents an overview of volcanic ash impacts on critical infrastructure, other than aviation and fuel supply, illustrated by findings from impact assessment reconnaissance trips carried out to a wide range of locations worldwide by our international research group and local collaborators. ‘Critical infrastructure’ includes those assets, frequently taken for granted, which are essential for the functioning of a society and economy. Electricity networks are very vulnerable to disruption from volcanic ash falls. This is particularly the case when fine ash is erupted because it has a greater tendency to adhere to line and substation insulators, where it can cause flashover (unintended electrical discharge) which can in turn cause widespread and disruptive outages. Weather conditions are a major determinant of flashover risk. Dry ash is not conductive, and heavy rain will wash ash from insulators, but light rain/mist will mobilise readily-soluble salts on the surface of the ash grains and lower the ash layer’s resistivity. Wet ash is also heavier than dry ash, increasing the risk of line breakage or tower/pole collapse. Particular issues for water

  1. Magnetic properties of frictional volcanic materials

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan; Biggin, Andrew; Ferk, Annika; Leonhardt, Roman

    2015-04-01

    During dome-building volcanic eruptions, highly viscous magma extends through the upper conduit in a solid-like state. The outer margins of the magma column accommodate the majority of the strain, while the bulk of the magma is able to extrude, largely undeformed, to produce magma spines. Spine extrusion is often characterised by the emission of repetitive seismicity, produced in the upper <1 km by magma failure and slip at the conduit margins. The rheology of the magma controls the depth at which fracture can occur, while the frictional properties of the magma are important in controlling subsequent marginal slip processes. Upon extrusion, spines are coated by a carapace of volcanic fault rocks which provide insights into the deeper conduit processes. Frictional samples from magma spines at Mount St. Helens (USA), Soufriere Hills (Montserrat) and Mount Unzen (Japan) have been examined using structural, thermal and magnetic analyses to reveal a history of comminution, frictional heating, melting and cooling to form volcanic pseudotachylyte. Pseudotachylyte has rarely been noted in volcanic materials, and the recent observation of its syn-eruptive formation in dome-building volcanoes was unprecedented. The uniquely high thermal conditions of volcanic environments means that frictional melt remains at elevated temperatures for longer than usual, causing slow crystallisation, preventing the development of some signature "quench" characteristics. As such, rock-magnetic tests have proven to be some of the most useful tools in distinguishing pseudotachylytes from their andesite/ dacite hosts. In volcanic pseudotachylyte the mass normalised natural remanent magnetisation (NRM) when further normalised with the concentration dependent saturation remanence (Mrs) was found to be higher than the host rock. Remanence carriers are defined as low coercive materials across all samples, and while the remanence of the host rock displays similarities to an anhysteretic remanent

  2. The scaling of experiments on volcanic systems

    Directory of Open Access Journals (Sweden)

    Olivier eMERLE

    2015-06-01

    Full Text Available In this article, the basic principles of the scaling procedure are first reviewed by a presentation of scale factors. Then, taking an idealized example of a brittle volcanic cone intruded by a viscous magma, the way to choose appropriate analogue materials for both the brittle and ductile parts of the cone is explained by the use of model ratios. Lines of similarity are described to show that an experiment simulates a range of physical processes instead of a unique natural case. The pi theorem is presented as an alternative scaling procedure and discussed through the same idealized example to make the comparison with the model ratio procedure. The appropriateness of the use of gelatin as analogue material for simulating dyke formation is investigated. Finally, the scaling of some particular experiments such as pyroclastic flows or volcanic explosions is briefly presented to show the diversity of scaling procedures in volcanology.

  3. Volcanic emission of radionuclides and magma dynamics

    International Nuclear Information System (INIS)

    Lambert, G.; Le Cloarec, M.F.; Ardouin, B.; Le Roulley, J.C.

    1985-01-01

    210 Pb, 210 Bi and 210 Po, the last decay products of the 238 U series, are highly enriched in volcanic plumes, relative to the magma composition. Moreover this enrichment varies over time and from volcano to volcano. A model is proposed to describe 8 years of measurements of Mt. Etna gaseous emissions. The lead and bismuth coefficients of partition between gaseous and condensated phases in the magma are determined by comparing their concentrations in lava flows and condensated volatiles. In the case of volatile radionuclides, an escaping time is calculated which appears to be related to the volcanic activity. Finally, it is shown that that magma which is degassing can already be partly degassed; it should be considered as a mixture of a few to 50% of deep non-degassed magma with a well degassed superficial magma cell. (orig.)

  4. Seasonal variations of volcanic eruption frequencies

    Science.gov (United States)

    Stothers, Richard B.

    1989-01-01

    Do volcanic eruptions have a tendency to occur more frequently in the months of May and June? Some past evidence suggests that they do. The present study, based on the new eruption catalog of Simkin et al.(1981), investigates the monthly statistics of the largest eruptions, grouped according to explosive magnitude, geographical latitude, and year. At the 2-delta level, no month-to-month variations in eruption frequency are found to be statistically significant. Examination of previously published month-to-month variations suggests that they, too, are not statistically significant. It is concluded that volcanism, at least averaged over large portions of the globe, is probably not periodic on a seasonal or annual time scale.

  5. Top mass in ATLAS and CMS

    CERN Document Server

    Castro, A.

    2017-01-01

    Top quarks are produced copiously at the LHC, and a variety of related measurements has been made in the recent years by the two collaborations ATLAS and CMS. The most recent measurements of the top quark mass by the two collaborations are reported here. The top quark mass has been measured with a relative uncertainty smaller than 0.3pct, making the top quark the most accurately measured quark.

  6. New Physics in Single-Top Production

    CERN Document Server

    Kind, OM; The ATLAS collaboration

    2013-01-01

    In this presentation for TOP 2013 the latest results on searches of physics beyond the Standard Model using single-top signatures from CDF, CMS, D0 and ATLAS are collected. This includes searches for unknown resonances like W' or b*, measurements of the W helicity fractions and top polarisation in single-top events, as well as tests for CP violation, FCNC or anomalous weak couplings.

  7. MHD Integrated Topping Cycle Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    The overall objective of the project is to design and construct prototypical hardware for an integrated MHD topping cycle, and conduct long duration proof-of-concept tests of integrated system at the US DOE Component Development and Integration Facility in Butte, Montana. The results of the long duration tests will augment the existing engineering design data base on MHD power train reliability, availability, maintainability, and performance, and will serve as a basis for scaling up the topping cycle design to the next level of development, an early commercial scale power plant retrofit. The components of the MHD power train to be designed, fabricated, and tested include: A slagging coal combustor with a rated capacity of 50 MW thermal input, capable of operation with an Eastern (Illinois {number sign}6) or Western (Montana Rosebud) coal, a segmented supersonic nozzle, a supersonic MHD channel capable of generating at least 1.5 MW of electrical power, a segmented supersonic diffuser section to interface the channel with existing facility quench and exhaust systems, a complete set of current control circuits for local diagonal current control along the channel, and a set of current consolidation circuits to interface the channel with the existing facility inverter.

  8. Coping with volcanic hazards; a global perspective

    Science.gov (United States)

    Tilling, R.I.

    1990-01-01

    Compared to some other natural hazards-such as floods, storms, earthquakes, landslides- volcanic hazards strike infrequently. However, in populated areas , even very small eruptions can wreak havoc and cause widespread devastation. For example, the 13 November 1985 eruption of Nevado del Ruiz in Colombia ejected only about 3 percent of the volume of ash produced during the 18 May 1980 eruption of Mount St. Helens. Yet, the mudflows triggered by this tiny eruption killed more than 25,000 people.

  9. Feasibility study on volcanic power generation system

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-07-01

    Investigations were carried out to determine the feasibility of volcanic power generation on Satsuma Io Island. Earthquakes were studied, as were the eruptions of subaerial and submarine hot springs. Hydrothermal rock alteration was studied and electrical surveys were made. General geophysical surveying was performed with thermocameras and radiation monitoring equipment. In particular, the Toyoba mine was studied, both with respect to its hot spring and its subsurface temperatures.

  10. Crustal structure, evolution, and volcanic unrest of the Alban Hills, Central Italy

    Science.gov (United States)

    Chiarabba, C.; Amato, A.; Delaney, P.T.

    1997-01-01

    The Alban Hills, a Quaternary volcanic center lying west of the central Apennines, 15-25 km southeast of Rome, last erupted 19ka and has produced approximately 290 km3 of eruptive deposits since the inception of volcanism at 580 ka. Earthquakes of moderate intensity have been generated there at least since the Roman age. Modern observations show that intermittent periods of swarm activity originate primarily beneath the youngest features, the phreatomagmatic craters on the west side of the volcano. Results from seismic tomography allow identification of a low-velocity region, perhaps still hot or partially molten, more than 6 km beneath the youngest craters and a high-velocity region, probably a solidified magma body, beneath the older central volcanic construct. Thirty centimeters of uplift measured by releveling supports the contention that high levels of seismicity during the 1980s and 1990s resulted from accumulation of magma beneath these craters. The volume of magma accumulation and the amount of maximum uplift was probably at least 40 ?? 106 m3 and 40 cm, respectively. Comparison of newer levelings with those completed in 1891 and 1927 suggests earlier episodes of uplift. The magma chamber beneath the western Alban Hills is probably responsible for much of the past 200 ka of eruptive activity, is still receiving intermittent batches of magma, and is, therefore, continuing to generate modest levels of volcanic unrest. Bending of overburden is the most likely cause of the persistent earthquakes, which generally have hypocenters above the 6-km-deep top of the magma reservoir. In this view, the most recent uplift and seismicity are probably characteristic and not precursors of more intense activity.

  11. Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

    2014-06-01

    The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

  12. Geothermal and volcanism in west Java

    Science.gov (United States)

    Setiawan, I.; Indarto, S.; Sudarsono; Fauzi I, A.; Yuliyanti, A.; Lintjewas, L.; Alkausar, A.; Jakah

    2018-02-01

    Indonesian active volcanoes extend from Sumatra, Jawa, Bali, Lombok, Flores, North Sulawesi, and Halmahera. The volcanic arc hosts 276 volcanoes with 29 GWe of geothermal resources. Considering a wide distribution of geothermal potency, geothermal research is very important to be carried out especially to tackle high energy demand in Indonesia as an alternative energy sources aside from fossil fuel. Geothermal potency associated with volcanoes-hosted in West Java can be found in the West Java segment of Sunda Arc that is parallel with the subduction. The subduction of Indo-Australian oceanic plate beneath the Eurasian continental plate results in various volcanic products in a wide range of geochemical and mineralogical characteristics. The geochemical and mineralogical characteristics of volcanic and magmatic rocks associated with geothermal systems are ill-defined. Comprehensive study of geochemical signatures, mineralogical properties, and isotopes analysis might lead to the understanding of how large geothermal fields are found in West Java compared to ones in Central and East Java. The result can also provoke some valuable impacts on Java tectonic evolution and can suggest the key information for geothermal exploration enhancement.

  13. Global volcanic emissions: budgets, plume chemistry and impacts

    Science.gov (United States)

    Mather, T. A.

    2012-12-01

    Over the past few decades our understanding of global volcanic degassing budgets, plume chemistry and the impacts of volcanic emissions on our atmosphere and environment has been revolutionized. Global volcanic emissions budgets are needed if we are to make effective use of regional and global atmospheric models in order to understand the consequences of volcanic degassing on global environmental evolution. Traditionally volcanic SO2 budgets have been the best constrained but recent efforts have seen improvements in the quantification of the budgets of other environmentally important chemical species such as CO2, the halogens (including Br and I) and trace metals (including measurements relevant to trace metal atmospheric lifetimes and bioavailability). Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents and during electrical discharges in ash-rich volcanic plumes. These reactive trace species have important consequences for gas plume chemistry and impacts, for example, in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate. There are still many challenges and open questions to be addressed in this fascinating area of science.

  14. Neogene volcanism in Gutai Mts. (Eastern Carpathains: a review

    Directory of Open Access Journals (Sweden)

    Marinel Kovacs

    2003-04-01

    Full Text Available Two types of volcanism developed in Gutâi Mts. (inner volcanic chain of Eastern Carpathians: a felsic, extensional/“back-arc” type and an intermediate, arc type. The felsic volcanism of explosive origin, consisting of caldera-related rhyolitic ignimbrites and resedimented volcaniclastics, had taken place during Early-Middle Badenian and Early Sarmatian. The intermediate volcanism, consisting of extrusive (effusive and explosive and intrusive activity, had developed during Sarmatian and Pannonian (13.4-7.0 Ma. It is represented by typical calc-alkaline series, from basalts to rhyolites. Lava flows of basaltic andesites and andesites are predominant, often emplaced in subaqueous environment. Extrusive domes, mainly composed of dacites, are associated to the andesitic volcanic structures. The intermediate volcanism, consisting of extrusive (effusive and explosive and intrusive activity, had developed during Sarmatian and Pannonian (13.4-7.0 Ma. It is represented by typical calc-alkaline series, from basalts to rhyolites. Lava flows of basaltic andesites and andesites are predominant, often emplaced in subaqueous environment. Extrusive domes, mainly composed of dacites, are associated to the andesitic volcanic structures. The geochemical study on the volcanic rocks shows the calc-alkaline character of both felsic and intermediate volcanism and typical subduction zones geochemical signatures for the intermediate one. The felsic volcanism shows affinities with subduction-related rocks as well. The main petrogenetic process in Gutâi Mts. was crustal assimilation, strongly constrained by trace element and isotope geochemistry.

  15. Report on the combined meeting of the core confinement and internal transport barrier expert group, confinement database and modeling expert group and edge pedestal expert group, 12-16 April 1999, Garching

    International Nuclear Information System (INIS)

    Janeschitz, G.; Connor, J.W.; Cordey, G.; Kardaun, O.; Mukhovatov, V.; Stambaugh, R.; Ryter, F.; Wakatani, M.

    1999-01-01

    This contribution to the ITER EDA Newsletter reports on the combined meeting of the core confinement and internal transport barrier expert group, confinement database and modeling expert group and edge pedestal expert group in Garching, Germany. This is the first workshop of its kind after the re-organisation of the expert groups. The new scheme of the meetings, namely to permit more interaction between groups by arranging them at the same time and location turned out to be very successful. The main issues discussed were for the Confinement Database: merging of edge pedestal and confinement data, improvement of the density- and magnetic shape parameters, addition of new dedicated threshold data, the effect of different divertors in JET; for the H-Mode Power Threshold Database: assembly of a new version of the database with about 650 time points from 10 tokamaks; for the 1-D Modelling Workshop: management of the database after the re-organisation of the Joint Central Team an ongoing efforts in plasma transport modelling; for the newly formed pedestal group: issues of the H-mode shear layer at the plasma edge. There was also an executive summary given of a recent USA workshop on internal transport barriers and regimes with weak or negative magnetic shear

  16. Search for Single Top Production at LEP

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2002-01-01

    Single top production in e^+e^- annihilations is searched for in data collected by the L3 detector at centre-of-mass energies from 189 to 209 GeV, corresponding to a total integrated luminosity of 634 pb-1. Investigating hadronic and semileptonic top decays, no evidence of single top production at LEP is obtained and upper limits on the single top cross section as a function of the centre-of-mass energy are derived. Limits on possible anomalous couplings, as well as on the scale of contact interactions responsible for single top production are determined.

  17. Single top quark production with CMS

    Directory of Open Access Journals (Sweden)

    Piccolo Davide

    2013-11-01

    Full Text Available Measurements of single top quark production performed using the CMS experiment [1] data collected in 2011 at centre-of-mass energies of 7 TeV and in 2012 at 8 TeV, are presented. The cross sections for the electroweak production of single top quarks in the t-channel and in association with W-bosons is measured and the results are used to place constraints on the CKM matrix element Vtb. Measurements of top quark properties in single top quark production are also presented. The results include the measurement of the charge ratio in the single top t-channel.

  18. CP Violation in Single Top Quark Production

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Weigang [Michigan State Univ., East Lansing, MI (United States)

    2012-01-01

    We present a search for CP violation in single top quark production with the DØ experiment at the Tevatron proton-antiproton collider. CP violation in the top electroweak interaction results in different single top quark production cross sections for top and antitop quarks. We perform the search in the single top quark final state using 5.4 fb-1 of data, in the s-channel, t-channel, and for both combined. At this time, we do not see an observable CP asymmetry.

  19. Top quark physics at the LHC

    Directory of Open Access Journals (Sweden)

    Jeong Kim Tae

    2014-04-01

    Full Text Available In 2011, an integrated luminosity of more than 5 fb−1 at 7 TeV has been delivered by the LHC. The measurement of the cross section in top quark pair production and in single top quark production, top quark mass, top quark properties and new physics searches in top quark decays have been performed at the CMS experiment with various integrated luminosities. An overview of the latest results of these measurements and searches by the time of ICFP 2012 conference will be presented.

  20. Top flooding modeling with MAAP4 code

    International Nuclear Information System (INIS)

    Brunet-Thibault, E.; Marguet, S.

    2006-01-01

    An engineering top flooding model was developed in MAAP4.04d.4, the severe accident code used in EDF, to simulate the thermal-hydraulic phenomena that should take place if emergency core cooling (ECC) water was injected in hot leg during quenching. In the framework of the ISTC (International Science and Technology Centre), a top flooding test was proposed in the PARAMETER facility (Podolsk, Russia). The MAAP calculation of the PARAMETER top flooding test is presented in this paper. A comparison between top and bottom flooding was made on the bundle test geometry. According to this study, top flooding appears to cool quickly and effectively the upper plenum internals. (author)

  1. Searching for the top at UA2

    International Nuclear Information System (INIS)

    Unal, G.

    1990-10-01

    The projects conceived for searching the quark top, predicted by the Standard Model, are described. The required existence of the quark top from the Standard Model and its production from proton-antiproton collisions are reviewed. The UA2 experimental device is described. The method applied for the search of the top is explained. The analysis of the UA2 data does not allow to conclude the existence of the top. However, the low mass limit of 69 GeV/C 2 can be established for the top mass. The results of the analysis of the W decays into supersymmetric particles are included [fr

  2. Top Soils Geochemical and Radioactivity Survey of Naples (Italy) Metropolitan.

    Science.gov (United States)

    Somma, R.; De Vivo, B.; Cicchella, D.

    2001-05-01

    The metropolitan area of Naples due to intense human activities is an emblematic area affected by various environmental pollution of soils and waters in addition to hydrogeological volcanic, seismic and bradyseismic hazards. The geology of the area is prevailing represented by volcanics erupted, from the Upper Pleistocene to Recent by Mt. Somma-Vesuvius on the east and the Campi Flegrei fields on the west. The morphology of the metropolitan area of Naples city can be subdivided in flat areas, constituted by reworked pyroclastic terrains, and by hills originated by the overlapping of different welded pyroclastic flows (i.e.: Campanian Ignimbrite and Neapoletan Yellow Tuff) intercalated with pyroclastic deposits of different origins (i.e.: Campi Flegrei, Mt. Somma-Vesuvius, Ischia) and ages. In order to compile a multi-element baseline geochemical and radioactivity mapping of the metropolitan area of the Napoli we have sampled for this study, in situ top soil and imported filling material (mainly soil, volcanic ash, pumice and scoriae). The sampling and radioactivity survey has been carried out on about 200 sampling sites covering an area of about 150 Km2, with a grid of 0.5 x 0.5 km in the urbanised downtown and 1 km x 1 km in the sub urban areas. In each site has been determined a radioactivity by a Scintrex GRS-500 at different emission spectra as total radioactivity (> 0.08 MeV and > 0.40 MeV), 238U (at 1.76 MeV mostly from 214Bi), 232Th (at 2.6 MeV mostly from 208Tl) and 40K (at 1.46 MeV mostly for 40K). The range of values of in situ soils are as follow for the in situ soils (Total radioactivity: 1327- 360 and 114- 47; 238U: 2.6- 1.3; 40K: 8.1- 3.1; 232U: 0.5- 0.1). Analyses of major, metallic elements and pH of each soil sample are in progress, while Pb isotopes compositions, for a selected number of samples, will be determined to discriminate the natural (geogenic) from the anthropogenic components in the soils by versus the anthropogenetic origin. The data

  3. Volcanic styles at Alba Patera, Mars: implications of lava flow morphology to the volcanic history

    International Nuclear Information System (INIS)

    Schneeberger, D.M.; Pieri, D.C.

    1988-01-01

    Alba Patera presents styles of volcanism that are unique to Mars. Its very low profile, large areal extent, unusually long and voluminous lava flows, and circumferential graben make it among Mars' most interesting volcanic features. Clues to Alba's volcanic history are preserved in its morphology and stratigraphy. Understanding the relationship of lava flow morphology to emplacement processes should enable estimates of viscosity, effusion rate, and gross composition to be made. Lava flows, with dimensions considered enormous by terrestrial standards, account for a major portion of the exposed surface of Alba Patera. These flows exhibit a range of morphologies. While most previous works have focused on the planimetric characteristics, attention was drawn to the important morphological attributes, paying particular attention to what the features suggest about the emplacement process

  4. Geophysical expression of caldera related volcanism, structures and mineralization in the McDermitt volcanic field

    Science.gov (United States)

    Rytuba, J. J.; Blakely, R. J.; Moring, B.; Miller, R.

    2013-12-01

    The High Rock, Lake Owyhee, and McDermitt volcanic fields, consisting of regionally extensive ash flow tuffs and associated calderas, developed in NW Nevada and SE Oregon following eruption of the ca. 16.7 Ma Steens flood basalt. The first ash flow, the Tuff of Oregon Canyon, erupted from the McDermitt volcanic field at 16.5Ma. It is chemically zoned from peralkaline rhyolite to dacite with trace element ratios that distinguish it from other ash flow tuffs. The source caldera, based on tuff distribution, thickness, and size of lithic fragments, is in the area in which the McDermitt caldera (16.3 Ma) subsequently formed. Gravity and magnetic anomalies are associated with some but not all of the calderas. The White Horse caldera (15.6 Ma), the youngest caldera in the McDermitt volcanic field has the best geophysical expression, with both aeromagnetic and gravity lows coinciding with the caldera. Detailed aeromagnetic and gravity surveys of the McDermitt caldera, combined with geology and radiometric surveys, provides insight into the complexities of caldera collapse, resurgence, post collapse volcanism, and hydrothermal mineralization. The McDermitt caldera is among the most mineralized calderas in the world, whereas other calderas in these three Mid Miocene volcanic fields do not contain important hydrothermal ore deposits, despite having similar age and chemistry. The McDermitt caldera is host to Hg, U, and Li deposits and potentially significant resources of Ga, Sb, and REE. The geophysical data indicate that post-caldera collapse intrusions were important in formation of the hydrothermal systems. An aeromagnetic low along the E caldera margin reflects an intrusion at a depth of 2 km associated with the near-surface McDermitt-hot-spring-type Hg-Sb deposit, and the deeper level, high-sulfidation Ga-REE occurrence. The Li deposits on the W side of the caldera are associated with a series of low amplitude, small diameter aeromagnetic anomalies that form a continuous

  5. Top down electroweak dipole operators

    Science.gov (United States)

    Fuyuto, Kaori; Ramsey-Musolf, Michael

    2018-06-01

    We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark (dt) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale v, the dt arises from two gauge invariant operators generated at a scale Λ ≫ v that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on |dt |. Working in the leading log-squared approximation, we find that the present upper bound on |dt | is 10-19 e cm for Λ = 1 TeV, except in regions of finely tuned cancellations that allow for |dt | to be up to fifty times larger. Future de and dn probes may yield an order of magnitude increase in dt sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach.

  6. Using Volcanic Lightning Measurements to Discern Variations in Explosive Volcanic Activity

    Science.gov (United States)

    Behnke, S. A.; Thomas, R. J.; McNutt, S. R.; Edens, H. E.; Krehbiel, P. R.; Rison, W.

    2013-12-01

    VHF observations of volcanic lightning have been made during the recent eruptions of Augustine Volcano (2006, Alaska, USA), Redoubt Volcano (2009, Alaska, USA), and Eyjafjallajökull (2010, Iceland). These show that electrical activity occurs both on small scales at the vent of the volcano, concurrent with an eruptive event and on large scales throughout the eruption column during and subsequent to an eruptive event. The small-scale discharges at the vent of the volcano are often referred to as 'vent discharges' and are on the order of 10-100 meters in length and occur at rates on the order of 1000 per second. The high rate of vent discharges produces a distinct VHF signature that is sometimes referred to as 'continuous RF' radiation. VHF radiation from vent discharges has been observed at sensors placed as far as 100 km from the volcano. VHF and infrasound measurements have shown that vent discharges occur simultaneously with the onset of eruption, making their detection an unambiguous indicator of explosive volcanic activity. The fact that vent discharges are observed concurrent with explosive volcanic activity indicates that volcanic ejecta are charged upon eruption. VHF observations have shown that the intensity of vent discharges varies between eruptive events, suggesting that fluctuations in eruptive processes affect the electrification processes giving rise to vent discharges. These fluctuations may be variations in eruptive vigor or variations in the type of eruption; however, the data obtained so far do not show a clear relationship between eruption parameters and the intensity or occurrence of vent discharges. Further study is needed to clarify the link between vent discharges and eruptive behavior, such as more detailed lightning observations concurrent with tephra measurements and other measures of eruptive strength. Observations of vent discharges, and volcanic lightning observations in general, are a valuable tool for volcano monitoring, providing a

  7. Top Management Involvement in New Product Development

    DEFF Research Database (Denmark)

    Felekoglu, Burcu; Maier, Anja; Moultrie, James

    2010-01-01

    a broader conceptual space than this participation. This paper reviews the literature on top management involvement in new product development (NPD) and discusses relevance of different theoretical perspectives from other disciplines such as management, organisational behaviour and communication to analyse......Involvement of top managers in new product development (NPD) is a critical factor affecting NPD performance and frequently considered to be the participation of top management to certain activities in NPD or their NPD related behaviours. However, “Top management involvement in NPD” occupies...... antecedents, realisation and consequences of top management involvement in NPD. It is argued that top management has different involvement at different NPD levels: organisation level and project level. Resulting from this literature review, a tentative framework for top management involvement in NPD...

  8. Supervolcanoes within an ancient volcanic province in Arabia Terra, Mars.

    Science.gov (United States)

    Michalski, Joseph R; Bleacher, Jacob E

    2013-10-03

    Several irregularly shaped craters located within Arabia Terra, Mars, represent a new type of highland volcanic construct and together constitute a previously unrecognized Martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae possess a range of geomorphic features related to structural collapse, effusive volcanism and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulphur and erupted fine-grained pyroclastics from these calderas probably fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. The discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars.

  9. Radiation Characterization Summary: ACRR Cadmium-Polyethylene (CdPoly) Bucket Located in the Central Cavity on the 32-Inch Pedestal at the Core Centerline

    Energy Technology Data Exchange (ETDEWEB)

    Parma, Edward J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Naranjo, Gerald E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kaiser, Krista Irene [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Arnold, James F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lippert, Lance L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clovis, Ralph D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Lonnie E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Quirk, Thomas J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-10-01

    This document presents the facility-recommended characterization of the neutron, prompt gamma-ray, and delayed gamma-ray radiation fields in the Annular Core Research Reactor (ACRR) for the cadmium-polyethylene (CdPoly) bucket in the central cavity on the 32-inch pedestal at the core centerline. The designation for this environment is ACRR-CdPoly-CC-32-cl. The neutron, prompt gamma-ray, and delayed gamma-ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma-ray fluence profiles within the experiment area of the bucket. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples. Acknowledgements The authors wish to thank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work. Also thanks to Drew Tonigan for helping field the activation experiments in ACRR, David Samuel for helping to finalize the drawings and get the parts fabricated, and Elliot Pelfrey for preparing the active dosimetry plots.

  10. Ravimimüüjate TOP 30 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Ravimimüüjate TOP 30 aastal 2002. Käibe TOP 30. Kasumi TOP 30. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Ravimimüüjad 2002: üld- ja finantsandmed

  11. Tekstiilitööstuse TOP 30 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Tekstiilitööstuse TOP 30. Kasumi TOP 30. Käibe TOP 30. Rentaabluse TOP 20. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Omakapitali tootlikkuse TOP 20. Tekstiilitööstuse ettevõtted 2002: üld- ja finantsandmed

  12. Trükitööstuste TOP 50

    Index Scriptorium Estoniae

    2002-01-01

    Trükitööstuste TOP 50. Käibe TOP 30. Käibe kasum TOP 30. Kasvu TOP 30. Kasumi kasvu TOP 30. Rentaabluse TOP. Varade tootlikkuse TOP. Trükitööstusettevõtete üldandmed. Trükitööstusettevõtete finantsandmed

  13. Rõivatööstuse TOP 40 aastal 2002

    Index Scriptorium Estoniae

    2003-01-01

    Rõivatööstuse TOP 40. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Rõivatööstuse ettevõtted: üldandmed ja finantsandmed

  14. Läänemaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Läänemaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Läänemaa ettevõtete üld- ja finantsandmed

  15. Ida-Virumaa ettevõtete TOP 50

    Index Scriptorium Estoniae

    2005-01-01

    Ilmunud ka: Delovõje Vedomosti-Severo-Vostok 7. sept. lk. 4. Ida-Virumaa ettevõtete TOP 50; Käibe TOP 35; Kasumi TOP 35; Käibe kasvu TOP 20; Kasumi kasvu TOP 20; Rentaabluse TOP 20; Omakapitali tootlikkuse TOP 20; Ida-Virumaa ettevõtete üld- ja finantsandmed

  16. Toiduainetööstuse TOP 100 aastal 2001

    Index Scriptorium Estoniae

    2002-01-01

    TOP 100. Toiduainetööstuste rentaabluse TOP 40. Varade tootlikkuse TOP 40. Käibe TOP 50. Käibe kasvu TOP 50. Kasumi TOP 50. Kasumi kasvu TOP 50. Toiduainetööstuse finantsandmed aastal 2001. Toiduainetööstuse üldandmed aastal 2001

  17. Fluidal deep-sea volcanic ash as an indicator of explosive volcanism (Invited)

    Science.gov (United States)

    Clague, D. A.; Portner, R. A.; Paduan, J. B.; Dreyer, B. M.

    2013-12-01

    Fluidal glassy lava fragments are now known to be abundant at sites of submarine eruptions including the mid-ocean ridge system, near-ridge seamount chains, mid-plate volcanoes and the submarine rifts of ocean islands, deep-sea (4200m) alkalic lava fields, back-arc spreading centers, and arc volcanoes. Fluidal fragments at these diverse settings have compositions including basanite, tholeiite, boninite, andesite, dacite, and rhyolite. Fragments include straight, bent, curved, and coiled Pele's hair; flat, curved, twisted, folded, bent, or keeled ribbons; and flat, curved, or intensely folded limu o Pele. Most of these morphologies attach to blocky glass fragments. The fluidal fragments from different settings and depths are strikingly similar in morphology with variable vesicularity and particle thickness. They have been sampled flat and steep, rocky to sediment-covered substrates. Two different mechanisms are proposed to explain their origin: magmatic-volatile fragmentation during eruption and sea floor lava-water interactions. Volatiles in the melts and ambient water are present in all submarine volcanic settings, making it difficult to separate their role in forming the fragments. Submarine bubble-burst (strombolian) activity has been observed in situ at an active vent at -1200m on West Mata Volcano. However, lava-water interaction at elevated pressure has not been observed to make such fluidal fragments except in laboratory simulations. Lava-water interaction models suggest that pore water in sediment trapped beneath advancing lava flows migrates into the overlying flow where it expands to steam, and the expanding steam bubble escapes explosively through the flow top to form the fluidal fragments. This is different from the hollow (water-filled) pillars that form in inflating flows as trapped water escapes. Pillars grow upwards at contacts between flow lobes, thus the water exiting through pillars never enters (or exits) the molten lava flow interior. Another

  18. Volcanism Studies: Final Report for the Yucca Mountain Project

    International Nuclear Information System (INIS)

    Crowe, Bruce M.; Perry, Frank V.; Valentine, Greg A.; Bowker, Lynn M.

    1998-01-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt ( than about 7 x 10 -8 events yr -1 . Simple probability estimates are used to assess possible implications of not drilling aeromagnetic anomalies in the Amargosa Valley. The sensitivity of the disruption probability to the location of northeast boundaries of volcanic zones near the Yucca Mountain sit

  19. Sr isotopes at Copahue Volcanic Center, Neuquen, Argentina: Preliminary report

    International Nuclear Information System (INIS)

    Linares, E.; Ostera, H.A.; Cagnoni, M.C

    2001-01-01

    The Copahue Volcanic Center is located in the Cordillera Principal, at 38 L.S., in the Argentina- Chilean border. Detailed geological, geochronological and structural studies were carried out during the last decade (Pesce, 1989; Delpino y Bermudez, 1993; Linares et al., 1995, 1999; Folguera y Ramos, 2000; among others). We present Sr isotopes data on the main units of the Volcanic Center, coupled with a major element geochemistry, to constrain the evolution of the volcanic center (au)

  20. Eocene volcanism and the origin of horizon A

    Science.gov (United States)

    Gibson, T.G.; Towe, K.M.

    1971-01-01

    A series of closely time-equivalent deposits that correlate with seismic reflector horizon A exists along the coast of eastern North America. These sediments of Late-Early to Early-Middle Eocene age contain an authigenic mineral suite indicative of the alteration of volcanic glass. A volcanic origin for these siliceous deposits onshore is consistent with a volcanic origin for the cherts of horizon A offshore.

  1. Lääne-Virumaa TOP 100 aastal 2000

    Index Scriptorium Estoniae

    2001-01-01

    Lääne-Virumaa edukamad ettevõtted; Lääne-Virumaa käibe TOP 100; Käibe kasvu TOP 20; Käibe languse TOP 10; Kasumi TOP 20; Kasumi kasvu TOP 20; Rentabluse TOP 20; ROA TOP 20; Kasumi languse TOP 10; Kahjumi TOP 10; Lääne-Virumaa käibelt suuremate ettevõtete finantsandmed. Lääne-Virumaa ettevõtete üldandmed

  2. Volcanic Hazards in Site Evaluation for Nuclear Installations

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-10-15

    This publication provides comprehensive and updated guidance for site evaluation in relation to volcanic hazards. It includes recommendations on assessing the volcanic hazards at a nuclear installation site, in order to identify and characterize, in a comprehensive manner, all potentially hazardous phenomena that may be associated with future volcanic events. It describes how some of these volcanic phenomena may affect the acceptability of the selected site, resulting in exclusion of a site or determining the corresponding design basis parameters for the installation. This Safety Guide is applicable to both existing and new sites, and a graded approach is recommended to cater for all types of nuclear installations. Contents: 1. Introduction; 2. Overview of volcanic hazard assessment; 3. General recommendations; 4. Necessary information and investigations (database); 5. Screening of volcanic hazards; 6. Site specific volcanic hazard assessment; 7. Nuclear installations other than nuclear power plants; 8. Monitoring and preparation for response; 9. Management system for volcanic hazard assessment; Annex I: Volcanic hazard scenarios; Annex II: Worldwide sources of information.

  3. Constructional Volcanic Edifices on Mercury: Candidates and Hypotheses of Formation

    Science.gov (United States)

    Wright, Jack; Rothery, David A.; Balme, Matthew R.; Conway, Susan J.

    2018-04-01

    Mercury, a planet with a predominantly volcanic crust, has perplexingly few, if any, constructional volcanic edifices, despite their common occurrence on other solar system bodies with volcanic histories. Using image and topographical data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, we describe two small (Earth and the Moon. Though we cannot definitively conclude that these landforms are volcanic, the paucity of constructional volcanic edifices on Mercury is intriguing in itself. We suggest that this lack is because volcanic eruptions with sufficiently low eruption volumes, rates, and flow lengths, suitable for edifice construction, were highly spatiotemporally restricted during Mercury's geological history. We suggest that volcanic edifices may preferentially occur in association with late-stage, postimpact effusive volcanic deposits. The European Space Agency/Japan Aerospace Exploration Agency BepiColombo mission to Mercury will be able to investigate further our candidate volcanic edifices; search for other, as-yet unrecognized edifices beneath the detection limits of MESSENGER data; and test our hypothesis that edifice construction is favored by late-stage, low-volume effusive eruptions.

  4. Basaltic volcanic episodes of the Yucca Mountain region

    International Nuclear Information System (INIS)

    Crowe, B.M.

    1990-01-01

    The purpose of this paper is to summarize briefly the distribution and geologic characteristics of basaltic volcanism in the Yucca Mountain region during the last 10--12 Ma. This interval largely postdates the major period of silicic volcanism and coincides with and postdates the timing of major extensional faulting in the region. Field and geochronologic data for the basaltic rocks define two distinct episodes. The patterns in the volume and spatial distribution of these basaltic volcanic episodes in the central and southern part of the SNVF are used as a basis for forecasting potential future volcanic activity in vicinity of Yucca Mountain. 33 refs., 2 figs

  5. The relationship between carbonate facies, volcanic rocks and plant remains in a late Palaeozoic lacustrine system (San Ignacio Fm, Frontal Cordillera, San Juan province, Argentina)

    Science.gov (United States)

    Busquets, P.; Méndez-Bedia, I.; Gallastegui, G.; Colombo, F.; Cardó, R.; Limarino, O.; Heredia, N.; Césari, S. N.

    2013-07-01

    The San Ignacio Fm, a late Palaeozoic foreland basin succession that crops out in the Frontal Cordillera (Argentinean Andes), contains lacustrine microbial carbonates and volcanic rocks. Modification by extensive pedogenic processes contributed to the massive aspect of the calcareous beds. Most of the volcanic deposits in the San Ignacio Fm consist of pyroclastic rocks and resedimented volcaniclastic deposits. Less frequent lava flows produced during effusive eruptions led to the generation of tabular layers of fine-grained, greenish or grey andesites, trachytes and dacites. Pyroclastic flow deposits correspond mainly to welded ignimbrites made up of former glassy pyroclasts devitrified to microcrystalline groundmass, scarce crystals of euhedral plagioclase, quartz and K-feldspar, opaque minerals, aggregates of fine-grained phyllosilicates and fiammes defining a bedding-parallel foliation generated by welding or diagenetic compaction. Widespread silicified and silica-permineralized plant remains and carbonate mud clasts are found, usually embedded within the ignimbrites. The carbonate sequences are underlain and overlain by volcanic rocks. The carbonate sequence bottoms are mostly gradational, while their tops are usually sharp. The lower part of the carbonate sequences is made up of mud which appear progressively, filling interstices in the top of the underlying volcanic rocks. They gradually become more abundant until they form the whole of the rock fabric. Carbonate on volcanic sandstones and pyroclastic deposits occur, with the nucleation of micritic carbonate and associated production of pyrite. Cyanobacteria, which formed the locus of mineral precipitation, were related with this nucleation. The growth of some of the algal mounds was halted by the progressive accumulation of volcanic ash particles, but in most cases the upper boundary is sharp and suddenly truncated by pyroclastic flows or volcanic avalanches. These pyroclastic flows partially destroyed the

  6. Mud volcanism of South-Caspian depression

    International Nuclear Information System (INIS)

    Aliyev, A.A.

    2002-01-01

    Full text : South-Caspian depression is presented by area of large warping with thick (more than 25 km) sedimentary series and with wide development of mud volcanism. This depression is unique according to its number of mud volcanoes and intensity of their eruptions. There are about 400 mud volcanoes in this area, which is more than than a half of all volcanoes of the planet. Among them - 220 are continental, more 170 are marine, defined by different methods in the South-Caspian aquatorium. As a result of mudvolcanic activity islands, banks, shoals and underwater ridges are formed in marine conditions. Depths of underwater volcanoes vary from few meters to 900 m as the height of cones are different too. Marine mud volcanoes in geological history of Caspian sea evolution and in its recent history had and important significance. Activity of mud volcanoes in sea conditions lead to the formation of positive elements of relief. Products of ejection take part in the formation of microrelief of surrounding areas of sea bottom influence upon its dynamics and composition of bottom sediments. The carried out comparative analysis of mud volcanism manifestation both onshore and offshore showed the basic differences and similarities in morphology of volcanoes and geology-geochemical peculiarities of eruption products. New data on tectonics of mud volcanism development has been obtained over recent years. Mud volcanoes of South-Caspian depression are studied for assessment and oil-gas content of deep-seated deposits. Geochemical method of search of oil and gas deposits in mudvolcanic areas had been worked out.

  7. Volcanism/tectonics working group summary

    International Nuclear Information System (INIS)

    Kovach, L.A.; Young, S.R.

    1995-01-01

    This article is a summary of the proceedings of a group discussion which took place at the Workshop on the Role of Natural Analogs in Geologic Disposal of High-Level Nuclear Waste in San Antonio, Texas on July 22-25, 1991. The working group concentrated on the subject of the impacts of earthquakes, fault rupture, and volcanic eruption on the underground repository disposal of high-level radioactive wastes. The tectonics and seismic history of the Yucca Mountain site in Nevada is discussed and geologic analogs to that site are described

  8. VOLCANIC RISK ASSESSMENT - PROBABILITY AND CONSEQUENCES

    International Nuclear Information System (INIS)

    G.A. Valentine; F.V. Perry; S. Dartevelle

    2005-01-01

    Risk is the product of the probability and consequences of an event. Both of these must be based upon sound science that integrates field data, experiments, and modeling, but must also be useful to decision makers who likely do not understand all aspects of the underlying science. We review a decision framework used in many fields such as performance assessment for hazardous and/or radioactive waste disposal sites that can serve to guide the volcanological community towards integrated risk assessment. In this framework the underlying scientific understanding of processes that affect probability and consequences drive the decision-level results, but in turn these results can drive focused research in areas that cause the greatest level of uncertainty at the decision level. We review two examples of the determination of volcanic event probability: (1) probability of a new volcano forming at the proposed Yucca Mountain radioactive waste repository, and (2) probability that a subsurface repository in Japan would be affected by the nearby formation of a new stratovolcano. We also provide examples of work on consequences of explosive eruptions, within the framework mentioned above. These include field-based studies aimed at providing data for ''closure'' of wall rock erosion terms in a conduit flow model, predictions of dynamic pressure and other variables related to damage by pyroclastic flow into underground structures, and vulnerability criteria for structures subjected to conditions of explosive eruption. Process models (e.g., multiphase flow) are important for testing the validity or relative importance of possible scenarios in a volcanic risk assessment. We show how time-dependent multiphase modeling of explosive ''eruption'' of basaltic magma into an open tunnel (drift) at the Yucca Mountain repository provides insight into proposed scenarios that include the development of secondary pathways to the Earth's surface. Addressing volcanic risk within a decision

  9. Hubble Captures Volcanic Eruption Plume From Io

    Science.gov (United States)

    1997-01-01

    The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter's large innermost moon.Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o'clock position, against the blue background of Jupiter's clouds. Io's volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.Until now, these plumes have only been seen by spacecraft near Jupiter, and their detection from the Earth-orbiting Hubble Space Telescope opens up new opportunities for long-term studies of these remarkable phenomena.The plume seen here is from Pele, one of Io's most powerful volcanos. Pele's eruptions have been seen before. In March 1979, the Voyager 1 spacecraft recorded a 300-km-high eruption cloud from Pele. But the volcano was inactive when the Voyager 2 spacecraft flew by Jupiter in July 1979. This Hubble observation is the first glimpse of a Pele eruption plume since the Voyager expeditions.Io's volcanic plumes are much taller than those produced by terrestrial volcanos because of a combination of factors. The moon's thin atmosphere offers no resistance to the expanding volcanic gases; its weak gravity (one-sixth that of Earth) allows material to climb higher before falling; and its biggest volcanos are more powerful than most of Earth's volcanos.This image is a contrast-enhanced composite of an ultraviolet image (2600 Angstrom wavelength), shown in blue, and a violet image (4100 Angstrom wavelength), shown in orange. The orange color probably occurs because of the absorption and/or scattering of ultraviolet light in the plume. This light from Jupiter passes through the plume and is

  10. Seismological evidence for a sub-volcanic arc mantle wedge beneath the Denali volcanic gap, Alaska

    Science.gov (United States)

    McNamara, D.E.; Pasyanos, M.E.

    2002-01-01

    Arc volcanism in Alaska is strongly correlated with the 100 km depth contour of the western Aluetian Wadati-Benioff zone. Above the eastern portion of the Wadati-Benioff zone however, there is a distinct lack of volcanism (the Denali volcanic gap). We observe high Poisson's ratio values (0.29-0.33) over the entire length of the Alaskan subduction zone mantle wedge based on regional variations of Pn and Sn velocities. High Poisson's ratios at this depth (40-70 km), adjacent to the subducting slab, are attributed to melting of mantle-wedge peridotites, caused by fluids liberated from the subducting oceanic crust and sediments. Observations of high values of Poisson's ratio, beneath the Denali volcanic gap suggest that the mantle wedge contains melted material that is unable to reach the surface. We suggest that its inability to migrate through the overlying crust is due to increased compression in the crust at the northern apex of the curved Denali fault.

  11. Modelling ground deformation patterns associated with volcanic processes at the Okataina Volcanic Centre

    Science.gov (United States)

    Holden, L.; Cas, R.; Fournier, N.; Ailleres, L.

    2017-09-01

    The Okataina Volcanic Centre (OVC) is one of two large active rhyolite centres in the modern Taupo Volcanic Zone (TVZ) in the North Island of New Zealand. It is located in a complex section of the Taupo rift, a tectonically active section of the TVZ. The most recent volcanic unrest at the OVC includes the 1315 CE Kaharoa and 1886 Tarawera eruptions. Current monitoring activity at the OVC includes the use of continuous GPS receivers (cGPS), lake levelling and seismographs. The ground deformation patterns preceding volcanic activity the OVC are poorly constrained and restricted to predictions from basic modelling and comparison to other volcanoes worldwide. A better understanding of the deformation patterns preceding renewed volcanic activity is essential to determine if observed deformation is related to volcanic, tectonic or hydrothermal processes. Such an understanding also means that the ability of the present day cGPS network to detect these deformation patterns can also be assessed. The research presented here uses the finite element (FE) modelling technique to investigate ground deformation patterns associated with magma accumulation and diking processes at the OVC in greater detail. A number of FE models are produced and tested using Pylith software and incorporate characteristics of the 1315 CE Kaharoa and 1886 Tarawera eruptions, summarised from the existing body of research literature. The influence of a simple ring fault structure at the OVC on the modelled deformation is evaluated. The ability of the present-day continuous GPS (cGPS) GeoNet monitoring network to detect or observe the modelled deformation is also considered. The results show the modelled horizontal and vertical displacement fields have a number of key features, which include prominent lobe based regions extending northwest and southeast of the OVC. The results also show that the ring fault structure increases the magnitude of the displacements inside the caldera, in particular in the

  12. Slab dehydration in Cascadia and its relationship to volcanism, seismicity, and non-volcanic tremor

    Science.gov (United States)

    Delph, J. R.; Levander, A.; Niu, F.

    2017-12-01

    The characteristics of subduction beneath the Pacific Northwest (Cascadia) are variable along strike, leading to the segmentation of Cascadia into 3 general zones: Klamath, Siletzia, and Wrangelia. These zones show marked differences in tremor density, earthquake density, seismicity rates, and the locus and amount of volcanism in the subduction-related volcanic arc. To better understand what controls these variations, we have constructed a 3D shear-wave velocity model of the upper 80 km along the Cascadia margin from the joint inversion of CCP-derived receiver functions and ambient noise surface wave data using 900 temporary and permanent broadband seismic stations. With this model, we can investigate variations in the seismic structure of the downgoing oceanic lithosphere and overlying mantle wedge, the character of the crust-mantle transition beneath the volcanic arc, and local to regional variations in crustal structure. From these results, we infer the presence and distribution of fluids released from the subducting slab and how they affect the seismic structure of the overriding lithosphere. In the Klamath and Wrangelia zones, high seismicity rates in the subducting plate and high tremor density correlate with low shear velocities in the overriding plate's forearc and relatively little arc volcanism. While the cause of tremor is debated, intermediate depth earthquakes are generally thought to be due to metamorphic dehydration reactions resulting from the dewatering of the downgoing slab. Thus, the seismic characteristics of these zones combined with rather sparse arc volcanism may indicate that the slab has largely dewatered by the time it reaches sub-arc depths. Some of the water released during earthquakes (and possibly tremor) may percolate into the overriding plate, leading to slow seismic velocities in the forearc. In contrast, Siletzia shows relatively low seismicity rates and tremor density, with relatively higher shear velocities in the forearc

  13. Top-of-Rail lubricant

    Energy Technology Data Exchange (ETDEWEB)

    Alzoubi, M. F.; Fenske, G. R.; Erck, R. A.; Boparai, A. S.

    2000-07-14

    Analysis of the volatile and semivolatile fractions collected after use of the TOR lubricant indicated that other than contaminants in the collection laboratory, no compounds on the EPA's Target Compound Lists (Tables 2 and 5) were detected in these fractions. The data of these qualitative analyses, given in the various tables in the text, indicate only the relative amounts of the tentatively identified compounds. The authors recommend that quantitative analysis be performed on the volatile and semivolatile fractions to allow confirmation of the tentatively identified compounds and to obtain absolute amounts of the detected compounds. Additionally, the semivolatile fraction should be analyzed by liquid chromatography/mass spectrometry to identify compounds that are not chromatographable under the temperature program used for determination of semivolatile compounds. Introducing the top-of-rail (TOR) lubricant into the wheel/rail interface results in a reduction of almost 60% of lateral friction force over the forces encountered under dry conditions. This reveals good potential for energy savings, as well as wear reduction, for railroad companies. In TOR lubrication, an increase in the angle of attack and axle load results in increased lateral friction and rate of lubricant consumption. The most efficient TOR lubricant quantity to be used in the wheel/rail interface must be calculated precisely according to the number of cars, axle loads, train speed, and angle of attack.

  14. Top medical news stories 2015

    Directory of Open Access Journals (Sweden)

    Robbins RA

    2015-12-01

    Full Text Available No abstract available. Article truncated after 150 words. Here is our list of the top seven medical news stories for 2015 with special emphasis on the Southwest. 7. Wearable health devices: A wave of wearable computing devices such as Fitbit and UP wristbands have people keeping track of how much they sit, stand, walk, climb stairs and calories they consume (1. These fitness-tracking devices herald a series of devices that will detect and monitor serious diseases. However, these so-called medical-grade wearables require approval from the U.S. Food and Drug Administration, a regulatory hurdle avoided by the fitness-tracking devices which will likely slow their introduction. 6. Caitlyn Jenner: Caitlyn Jenner became the most famous transgender woman in the world following an interview published in Vanity Fair (2. The Vanity Fair website saw 11.6 million visits curious about the former Olympic athlete. Though Jenner publicly shared her gender identity, many transgender Americans do not-12% of gender non-conforming adults said they ...

  15. Measurement of top properties in ATLAS

    CERN Document Server

    Veloso, F; The ATLAS collaboration

    2010-01-01

    The top quark may play a special role in the Standard Model of particle physics. It is, for instance, the heaviest fundamental particle known, with a mass close to the electroweak symmetry breaking scale. Millions of top quark pairs will be produced per year at the LHC at nominal luminosity. ATLAS will measure many of the top quark properties with unprecedented precision. The ATLAS sensitivity studies done with Monte Carlo for the measurements of the top quark mass, the top quark charge, rare top quark decays and flavour changing neutral currents, the $t\\bar t$ spin correlations and $W$ boson polarization, the anomalous couplings at the $Wtb$ vertex and $t\\bar t$ resonances are reviewed.

  16. Qinshan CANDU project open top construction method

    International Nuclear Information System (INIS)

    Petrunik, K.J.; Wittann, K.; Khan, A.; Ricciuti, R.; Ivanov, A.; Chen, S.

    2003-01-01

    The significant schedule reductions achieved on the Qinshan CANDU Project were due in large part to the incorporation of advanced construction technologies in project design and delivery. For the Qinshan Project, a number of key advantages were realized through the use of the 'Open Top' construction method. This paper discusses the Qinshan Phase III CANDU Project Open Top implementation method. The Open Top method allowed major equipment to be installed simply, via the use of a Very Heavy Lift (VHL) crane and permitted the use of large-scale modularization. The advantages of Open Top construction, such as simplified access, more flexible project scheduling, improved construction safety and quality, and reduced labours are presented. The large-scale modularization of the Reactor Building Dousing System and the Open Top installation method and advantages relative to traditional CANDU 6 construction practices are also presented. Finally, major improvements for future CANDU plant construction using the Open Top method are discussed. (author)

  17. The significance of the heavy top quark

    International Nuclear Information System (INIS)

    Simmons, Elizabeth H.

    1997-01-01

    Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to accommodate a heavy top quark within existing frameworks have revealed constraints on model-building. Other investigations have started from the premise that a large top quark mass could signal a qualitative difference between the top quark and other fermions, perhaps in the form of new interactions peculiar to the top quark. Such new dynamics may also help answer existing questions about electroweak and flavor physics. This talk explores the implications of the heavy top quark in the context of weakly-coupled (e.g., SUSY) and strongly-coupled (e.g., technicolor) theories of electroweak symmetry breaking

  18. Top quark mass measurements with CMS

    CERN Document Server

    Kovalchuk, Nataliia

    2017-01-01

    Measurements of the top quark mass are presented, obtained from CMS data collected in proton-proton collisions at the LHC at centre-of-mass energies of 7 TeV and 8 TeV. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark, an analysis of endpoint spectra as well as measurements from shapes of top quark decay distributions. The dependence of the mass measurement on the kinematic phase space is investigated. The results of the various channels are combined and compared to the world average. The top mass and also $\\alpha_{\\textnormal S}$ are extracted from the top pair cross section measured at CMS.

  19. TOP500 Supercomputers for November 2004

    Energy Technology Data Exchange (ETDEWEB)

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2004-11-08

    24th Edition of TOP500 List of World's Fastest Supercomputers Released: DOE/IBM BlueGene/L and NASA/SGI's Columbia gain Top Positions MANNHEIM, Germany; KNOXVILLE, Tenn.; BERKELEY, Calif. In what has become a closely watched event in the world of high-performance computing, the 24th edition of the TOP500 list of the worlds fastest supercomputers was released today (November 8, 2004) at the SC2004 Conference in Pittsburgh, Pa.

  20. TOP500 Supercomputers for June 2004

    Energy Technology Data Exchange (ETDEWEB)

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2004-06-23

    23rd Edition of TOP500 List of World's Fastest Supercomputers Released: Japan's Earth Simulator Enters Third Year in Top Position MANNHEIM, Germany; KNOXVILLE, Tenn.;&BERKELEY, Calif. In what has become a closely watched event in the world of high-performance computing, the 23rd edition of the TOP500 list of the world's fastest supercomputers was released today (June 23, 2004) at the International Supercomputer Conference in Heidelberg, Germany.

  1. Top Quark Production at Hadron Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Phaf, Lukas Kaj [Univ. of Amsterdam (Netherlands)

    2004-03-01

    This thesis describes both theoretical and experimental research into top quark production. The theoretical part contains a calculation of the single-top quark production cross section at hadron colliders, at Next to Leading Order (NLO) accuracy. The experimental part describes a measurement of the top quark pair production cross section in proton-antiproton collisions, at a center of mass energy of 1.96 TeV.

  2. A table top exercise and workshop

    International Nuclear Information System (INIS)

    Lakey, J.R.A.

    1992-01-01

    Table top exercises are widely applied in training for emergency preparedness and have long been a feature of Courses on Planning for Nuclear Emergencies. Experience of a large number of table top exercises is used to provide a classification of the types of exercise indicating the application and the disadvantages. The use of workshops is considered to be complementary rather than an alternative to teaching methods available from table top exercises. (author)

  3. Paleomagnetism of the Neoproterozoic Mount Harper Volcanic Complex, Canada

    Science.gov (United States)

    Eyster, A. E.; Macdonald, F. A.; O'Connell, R. J.

    2012-12-01

    Paleomagnetism can be used to identify apparent polar wander, which involves contributions from plate tectonics and true polar wander. True polar wander events have been suggested to have played an important role throughout Earth's history. The Neoproterozoic Mount Harper Volcanic Complex (MHVC) provides paleomagnetic data that bears on this issue. The MHVC is located in the southern Ogilvie Mountains in the Yukon Territory, on the north-west corner of the Laurentian craton. The MHVC involves up to 1200 m of basaltic and andesitic flows. The MHVC reflects the propagating rifting event involved in the breakup of the supercontinent Rodinia. The MHVC is well dated with an age of 717.43± 0.14Ma from the top (Macdonald et al., Science, 2010). Below the MHVC are alluvial fan conglomerate and sandstone from Proterozoic normal faulting. Above the MHVC is a glacial diamictite dated to 716.47± 0.24 Ma and related to Snowball Earth glaciation (Macdonald et al., Science, 2010). Both block and core samples were collected from different members of the MHVC for paleomagnetic study. Included in the sampling were several stratigraphic sections. Alternating field and thermal stepwise demagnetization methods were used to analyze specimens. Magnetic components were determined using principal component analysis and Fisher statistical procedures were used to calculate mean directions. The stratigraphically sampled basalt flows yielded two components. One was a common secondary overprint, and the other was a high stability component which yielded two different directions. One pole is the same as the accepted Neoproterozoic Laurentian grand mean pole and the other is ˜50 degrees away from this grand mean pole. Several possible interpretations are explored- tectonic rotation, true polar wander or the presence of a non-dipolar geomagnetic field.

  4. VOLCANIC TSUNAMI GENERATING SOURCE MECHANISMS IN THE EASTERN CARIBBEAN REGION

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2004-01-01

    Full Text Available Earthquakes, volcanic eruptions, volcanic island flank failures and underwater slides have generated numerous destructive tsunamis in the Caribbean region. Convergent, compressional and collisional tectonic activity caused primarily from the eastward movement of the Caribbean Plate in relation to the North American, Atlantic and South American Plates, is responsible for zones of subduction in the region, the formation of island arcs and the evolution of particular volcanic centers on the overlying plate. The inter-plate tectonic interaction and deformation along these marginal boundaries result in moderate seismic and volcanic events that can generate tsunamis by a number of different mechanisms. The active geo-dynamic processes have created the Lesser Antilles, an arc of small islands with volcanoes characterized by both effusive and explosive activity. Eruption mechanisms of these Caribbean volcanoes are complex and often anomalous. Collapses of lava domes often precede major eruptions, which may vary in intensity from Strombolian to Plinian. Locally catastrophic, short-period tsunami-like waves can be generated directly by lateral, direct or channelized volcanic blast episodes, or in combination with collateral air pressure perturbations, nuéss ardentes, pyroclastic flows, lahars, or cascading debris avalanches. Submarine volcanic caldera collapses can also generate locally destructive tsunami waves. Volcanoes in the Eastern Caribbean Region have unstable flanks. Destructive local tsunamis may be generated from aerial and submarine volcanic edifice mass edifice flank failures, which may be triggered by volcanic episodes, lava dome collapses, or simply by gravitational instabilities. The present report evaluates volcanic mechanisms, resulting flank failure processes and their potential for tsunami generation. More specifically, the report evaluates recent volcanic eruption mechanisms of the Soufriere Hills volcano on Montserrat, of Mt. Pel

  5. Top Physics at CMS/LHC

    Directory of Open Access Journals (Sweden)

    Daskalakis Georgios

    2017-01-01

    Full Text Available Recent results on the inclusive and differential production cross sections of top-quark pair and single top-quark processes are presented, obtained using data from proton-proton collisions collected with the CMS detector at the LHC. The large centre-of-mass energies available at LHC allow for the copious production of top-quark pairs in association with other final state particles at high transverse momentum. Measurements of such processes as well as of the top-quark mass and other properties will be discussed. The results are compared with the most up-to-date standard model theory predictions.

  6. Differential Top Cross-section Measurements

    CERN Document Server

    Fenton, Michael James; The ATLAS collaboration

    2017-01-01

    The top quark is the heaviest known fundamental particle. The measurement of the differential top-quark pair production cross-section provides a stringent test of advanced perturbative QCD calculations. The ATLAS collaboration has performed detailed measurements of those differential cross sections at a centre-of-mass energy of 13 TeV. This talk focuses on differential cross-section measurements in the lepton+jets final state, including using boosted top quarks to probe our understanding of top quark production in the TeV regime.

  7. Top quark production cross-section measurements

    CERN Document Server

    Chen, Ye; The ATLAS collaboration

    2017-01-01

    Measurements of the inclusive and differential cross-sections for top-quark pair and single top production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at center-of-mass energies of 8 TeV and 13 TeV. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. These measurements, including results using boosted tops, probe our understanding of top-pair production in the TeV regime. The results are compared to Monte Carlo generators implementing LO and NLO matrix elements matched with parton showers and NLO QCD calculations. For the t-channel single top measurement, the single top-quark and anti-top-quark total production cross-sections, their ratio, as well as differential cross sections are also presented. A measurement of the production cross-section of a single top quark in association with a W boson, the second largest single-top production mode, is also presented. Finally, measurements of ...

  8. Beyond baking soda: Demonstrating the link between volcanic eruptions and viscosity to all ages

    Science.gov (United States)

    Smithka, I. N.; Walters, R. L.; Harpp, K. S.

    2014-12-01

    Public interest in volcanic eruptions and societal relevance of volcanic hazards provide an excellent basis for successful earth science outreach. During a museum-based earth science outreach event free and open to the public, we used two new interactive experiments to illustrate the relationship between gas content, magma viscosity, and eruption style. Learning objectives for visitors are to understand: how gas drives volcanic eruptions, the differences between effusive and explosive eruption styles, viscosity's control on gas pressure within a magma reservoir, and the role of gas pressure on eruption style. Visitors apply the scientific method by asking research questions and testing hypotheses by conducting the experiments. The demonstrations are framed with real life examples of volcanic eruptions (e.g., Mt. St. Helens eruption in 1980), providing context for the scientific concepts. The first activity demonstrates the concept of fluid viscosity and how gas interacts with fluids of different viscosities. Visitors blow bubbles into water and corn syrup. The corn syrup is so viscous that bubbles are trapped, showing how a more viscous material builds up higher gas pressure. Visitors are asked which kind of magma (high or low viscosity) will produce an explosive eruption. To demonstrate an explosive eruption, visitors add an Alka-Seltzer tablet to water in a snap-top film canister. The reaction rapidly produces carbon dioxide gas, increasing pressure in the canister until the lid pops off and the canister launches a few meters into the air (tinyurl.com/nzsgfoe). Increasing gas pressure in the canister is analogous to gas pressure building within a magma reservoir beneath a volcano. The lid represents high-viscosity magma that prevents degassing, causing gas pressure to reach explosive levels. This interactive activity is combined with a display of an effusive eruption: add vinegar to baking soda in a model volcano to produce a quick-flowing eruption. These

  9. Radiative impact of Etna volcanic aerosols over south eastern Italy on 3 December 2015

    Science.gov (United States)

    Romano, S.; Burlizzi, P.; Kinne, S.; De Tomasi, F.; Hamann, U.; Perrone, M. R.

    2018-06-01

    Irradiance and LiDAR measurements at the surface combined with satellite products from SEVIRI (Spinning Enhanced Visible and InfraRed Imager) and MODIS (MODerate resolution Imaging Spectroradiometer) were used to detect and characterize the Etna volcano (Italy) plume that crossed southeastern Italy on 3 December 2015, from about 10:00 up to 11:30 UTC, and estimate its radiative impact. The volcanic plume was delivered by a violent and short paroxysmal eruption that occurred from 02:30 to 03:10 UTC of 3 December 2015, about 400 km away from the monitoring site. Measurements from the LiDAR combined with model results showed that the aerosol optical depth of the volcanic plume, located from about 11 to 13 km above sea level (asl), was equal to 0.80 ± 0.07 at 532 nm. A low tropospheric aerosol load, located up to about 7 km asl, with optical depth equal to 0.19 ± 0.01 at 532 nm was also revealed by the LiDAR measurements. Short-Wave (SW) downward and upward irradiance measurements revealed that the instantaneous SW direct radiative forcing at the surface (DRFsurf) decreased to -146 ± 16 W m-2 at 10:50 UTC because of the volcanic plume passage. A Two-Stream radiative transfer model integrated with experimental measurements, which took into account the volcanic plume and the low tropospheric aerosol properties, was used to reproduce the SW radiative flux measurements at the surface and estimate the aerosol DRF both at the top of the atmosphere (TOA) and at the surface, in addition to the aerosol heating rate vertical profile. We found that the clear-sky, instantaneous, SW DRF at the TOA and the atmospheric forcing were equal to -112 and 33 W m-2, respectively, at 10:50 UTC that represented the time at which the volcanic plume radiative impact was the highest. The SW aerosol heating rate reached the peak value of 1.24 K day-1 at 12 km asl and decreased to -0.06 K day-1 at 11 km asl, at 10:50 UTC. The role of the aerosol load located up to about 7 km asl and the

  10. Explosive volcanism on Mercury: Analysis of vent and deposit morphology and modes of eruption

    Science.gov (United States)

    Jozwiak, Lauren M.; Head, James W.; Wilson, Lionel

    2018-03-01

    The MESSENGER mission revealed, for the first time, conclusive evidence of explosive volcanism on Mercury. Several previous works have cataloged the appearance and location of explosive volcanism on the planet using a variety of identifying characteristics, including vent presence and deposit color as seen in multispectral image mosaics. We present here a comprehensive catalog of vents of likely volcanic origin; our classification scheme emphasizes vent morphology. We have analyzed the morphologies of all vents in our catalog, and recognize three main morphologies: "simple vent", "pit vent", and "vent-with-mound". The majority of vents we identify are located within impact craters. The spatial distribution of vents does not correlate with the locations of volcanic smooth plains deposits, in contrast to the Moon, nor do vents correlate with the locations of large impact basins (except for the Caloris and Tolstoj basins). Using the degradation state of the vent host crater as a proxy for maximum age, we suggest that vent formation has been active through the Mansurian and into the Kuiperian periods, although the majority of vents were likely formed much earlier in mercurian history. The morphologies and locations of vents are used to investigate a set of plausible formation geometries. We find that the most likely and most prevalent formation geometry is that of a dike, stalled at depth, which then explosively vents to the surface. We compare the vent and deposit size of mercurian pyroclastic deposits with localized and regional lunar pyroclastic deposits, and find a range of possible eruption energies and corresponding variations in eruption style. Localized lunar pyroclastic deposits and the majority of mercurian pyroclastic deposits show evidence for eruption that is consistent with the magmatic foam at the top of a dike reaching a critical gas volume fraction. A subset of mercurian vents, including the prominent Copland-Rachmaninoff vent to the northeast of the

  11. Reduced cooling following future volcanic eruptions

    Science.gov (United States)

    Hopcroft, Peter O.; Kandlbauer, Jessy; Valdes, Paul J.; Sparks, R. Stephen J.

    2017-11-01

    Volcanic eruptions are an important influence on decadal to centennial climate variability. Large eruptions lead to the formation of a stratospheric sulphate aerosol layer which can cause short-term global cooling. This response is modulated by feedback processes in the earth system, but the influence from future warming has not been assessed before. Using earth system model simulations we find that the eruption-induced cooling is significantly weaker in the future state. This is predominantly due to an increase in planetary albedo caused by increased tropospheric aerosol loading with a contribution from associated changes in cloud properties. The increased albedo of the troposphere reduces the effective volcanic aerosol radiative forcing. Reduced sea-ice coverage and hence feedbacks also contribute over high-latitudes, and an enhanced winter warming signal emerges in the future eruption ensemble. These findings show that the eruption response is a complex function of the environmental conditions, which has implications for the role of eruptions in climate variability in the future and potentially in the past.

  12. Supercomputer modeling of volcanic eruption dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kieffer, S.W. [Arizona State Univ., Tempe, AZ (United States); Valentine, G.A. [Los Alamos National Lab., NM (United States); Woo, Mahn-Ling [Arizona State Univ., Tempe, AZ (United States)

    1995-06-01

    Our specific goals are to: (1) provide a set of models based on well-defined assumptions about initial and boundary conditions to constrain interpretations of observations of active volcanic eruptions--including movies of flow front velocities, satellite observations of temperature in plumes vs. time, and still photographs of the dimensions of erupting plumes and flows on Earth and other planets; (2) to examine the influence of subsurface conditions on exit plane conditions and plume characteristics, and to compare the models of subsurface fluid flow with seismic constraints where possible; (3) to relate equations-of-state for magma-gas mixtures to flow dynamics; (4) to examine, in some detail, the interaction of the flowing fluid with the conduit walls and ground topography through boundary layer theory so that field observations of erosion and deposition can be related to fluid processes; and (5) to test the applicability of existing two-phase flow codes for problems related to the generation of volcanic long-period seismic signals; (6) to extend our understanding and simulation capability to problems associated with emplacement of fragmental ejecta from large meteorite impacts.

  13. Robust satellite techniques for monitoring volcanic eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Pergola, N.; Pietrapertosa, C. [Consiglio Nazionale delle Ricerche, Istituto di Metodologie Avanzate, Tito Scalo, PZ (Italy); Lacava, T.; Tramutoli, V. [Potenza Universita' della Basilicata, Potenza (Italy). Dipt. di Ingegneria e Fisica dell' Ambiente

    2001-04-01

    Through this paper the robust approach to monitoring volcanic aerosols by satellite is applied to an extended set of events affecting Stromboli and Etna volcanoes to assess its performance in automated detection of eruptive clouds and in monitoring pre-eruptive emission activities. Using only NOAA/AVHRR data at hand (without any specific atmospheric model or ancillary ground-based measurements) the proposed method automatically discriminates meteorological from eruptive volcanic clouds and, in several cases, identified pre-eruptive anomalies in the emission rates not identified by traditional methods. The main merit of this approach is its effectiveness in recognising field anomalies also in the presence of a highly variable surface background as well as its intrinsic exportability not only on different geographic areas but also on different satellite instrumental packages. In particular, the possibility to extend the proposed method to the incoming new MSG/SEVIRI satellite package (which is going to fly next year) with its improved spectral (specific bands for SO{sub 2}) and temporal (up to 15 min) resolutions has been evaluated representing the natural continuation of this work.

  14. Viscosity characteristics of selected volcanic rock melts

    Science.gov (United States)

    Hobiger, Manuel; Sonder, Ingo; Büttner, Ralf; Zimanowski, Bernd

    2011-02-01

    A basic experimental study of the behavior of magma rheology was carried out on remelted volcanic rocks using wide gap viscometry. The complex composition of magmatic melts leads to complicated rheologic behavior which cannot be described with one simple model. Therefore, measurement procedures which are able to quantify non-Newtonian behavior have to be employed. Furthermore, the experimental apparatus must be able to deal with inhomogeneities of magmatic melts. We measured the viscosity of a set of materials representing a broad range of volcanic processes. For the lower viscous melts (low-silica compositions), non-Newtonian behavior is observed, whereas the high-silica melts show Newtonian behavior in the measured temperature and shear rate range (T = 1423 K - 1623 K, γ˙ = 10 - 2 s - 1 - 20 s - 1 ). The non-Newtonian materials show power-law behavior. The measured viscosities η and power-law indexes m lie in the intervals 8 Pa s ≤ η ≤ 210 3 Pa s, 0.71 ≤ m ≤ 1.0 (Grímsvötn basalt), 0.9 Pa s ≤ η ≤ 350 Pa s, 0.61 ≤ m ≤ 0.93 (Hohenstoffeln olivine-melilitite), and 8 Pa s ≤ η ≤ 1.510 4 Pa s, 0.55 ≤ m ≤ 1.0 (Sommata basalt). Measured viscosities of the Newtonian high-silica melts lie in the range 10 4 Pa s ≤ η ≤ 310 5 Pa s.

  15. The scientific management of volcanic crises

    Science.gov (United States)

    Marzocchi, Warner; Newhall, Christopher; Woo, Gordon

    2012-12-01

    Sound scientific management of volcanic crises is the primary tool to reduce significantly volcanic risk in the short-term. At present, a wide variety of qualitative or semi-quantitative strategies is adopted, and there is not yet a commonly accepted quantitative and general strategy. Pre-eruptive processes are extremely complicated, with many degrees of freedom nonlinearly coupled, and poorly known, so scientists must quantify eruption forecasts through the use of probabilities. On the other hand, this also forces decision-makers to make decisions under uncertainty. We review the present state of the art in this field in order to identify the main gaps of the existing procedures. Then, we put forward a general quantitative procedure that may overcome the present barriers, providing guidelines on how probabilities may be used to take rational mitigation actions. These procedures constitute a crucial link between science and society; they can be used to establish objective and transparent decision-making protocols and also clarify the role and responsibility of each partner involved in managing a crisis.

  16. WSR-88D observations of volcanic ash

    Science.gov (United States)

    Wood, J.; Scott, C.; Schneider, D.

    2007-01-01

    Conclusions that may impact operations are summarized below: ??? Current VCPs may not be optimal for the scharacterization of volcanic events. Therefore, the development of a new VCP that combines the enhanced low level elevation density and increased temporal resolution of VCP 12 with the enhanced sensitivity of VCP 31. ??? Given currently available scan strategies, this preliminary investigation would suggest that it is advisable to use VCP 12 during the initial explosive phase of an eruptive event. Once the maximum reflectivity has dropped below 30 dBZ, VCP 31 should be used. ??? This study clearly indicates that WSR-88D Level II data offers many advantages over Level III data currently available in Alaska. The ability to access this data would open up greater opportunities for research. Given the proximity of WSR-88D platforms to active volcanoes in Alaska, as well as in the western Lower 48 states and Hawaii, radar data will likely play a major operational role when volcanic eruptions again pose a threat to life and property. The utilization of this tool to its maximum capability is vital.

  17. Nano-volcanic Eruption of Silver

    Science.gov (United States)

    Lin, Shih-Kang; Nagao, Shijo; Yokoi, Emi; Oh, Chulmin; Zhang, Hao; Liu, Yu-Chen; Lin, Shih-Guei; Suganuma, Katsuaki

    2016-10-01

    Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. Ag thin films are extensively used in modern electronics primarily because of their oxidation-resistance. Here we report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). It involves grain boundary liquation, the ejection of transient Ag-O fluids through grain boundaries, and the decomposition of Ag-O fluids into O2 gas and suspended Ag and Ag2O clusters. Subsequent coating with re-deposited Ag-O and the de-alloying of O yield a conformal amorphous Ag coating. Patterned Ag hillock arrays and direct Ag-to-Ag bonding can be formed by the homogenous crystallization of amorphous coatings. The Ag “nano-volcanic eruption” mechanism is elaborated, shedding light on a new mechanism of hillock formation and new applications of amorphous Ag coatings.

  18. Modulations of stratospheric ozone by volcanic eruptions

    Science.gov (United States)

    Blanchette, Christian; Mcconnell, John C.

    1994-01-01

    We have used a time series of aerosol surface based on the measurements of Hofmann to investigate the modulation of total column ozone caused by the perturbation to gas phase chemistry by the reaction N2O5(gas) + H2O(aero) yields 2HNO3(gas) on the surface of stratospheric aerosols. We have tested a range of values for its reaction probability, gamma = 0.02, 0.13, and 0.26 which we compared to unperturbed homogeneous chemistry. Our analysis spans a period from Jan. 1974 to Oct. 1994. The results suggest that if lower values of gamma are the norm then we would expect larger ozone losses for highly enhanced aerosol content that for larger values of gamma. The ozone layer is more sensitive to the magnitude of the reaction probability under background conditions than during volcanically active periods. For most conditions, the conversion of NO2 to HNO3 is saturated for reaction probability in the range of laboratory measurements, but is only absolutely saturated following major volcanic eruptions when the heterogeneous loss dominates the losses of N2O5. The ozone loss due to this heterogeneous reaction increases with the increasing chlorine load. Total ozone losses calculated are comparable to ozone losses reported from TOMS and Dobson data.

  19. Mantle updrafts and mechanisms of oceanic volcanism

    Science.gov (United States)

    Anderson, Don L.; Natland, James H.

    2014-10-01

    Convection in an isolated planet is characterized by narrow downwellings and broad updrafts-consequences of Archimedes' principle, the cooling required by the second law of thermodynamics, and the effect of compression on material properties. A mature cooling planet with a conductive low-viscosity core develops a thick insulating surface boundary layer with a thermal maximum, a subadiabatic interior, and a cooling highly conductive but thin boundary layer above the core. Parts of the surface layer sink into the interior, displacing older, colder material, which is entrained by spreading ridges. Magma characteristics of intraplate volcanoes are derived from within the upper boundary layer. Upper mantle features revealed by seismic tomography and that are apparently related to surface volcanoes are intrinsically broad and are not due to unresolved narrow jets. Their morphology, aspect ratio, inferred ascent rate, and temperature show that they are passively responding to downward fluxes, as appropriate for a cooling planet that is losing more heat through its surface than is being provided from its core or from radioactive heating. Response to doward flux is the inverse of the heat-pipe/mantle-plume mode of planetary cooling. Shear-driven melt extraction from the surface boundary layer explains volcanic provinces such as Yellowstone, Hawaii, and Samoa. Passive upwellings from deeper in the upper mantle feed ridges and near-ridge hotspots, and others interact with the sheared and metasomatized surface layer. Normal plate tectonic processes are responsible both for plate boundary and intraplate swells and volcanism.

  20. Developing International Guidelines on Volcanic Hazard Assessments for Nuclear Facilities

    Science.gov (United States)

    Connor, Charles

    2014-05-01

    Worldwide, tremendous progress has been made in recent decades in forecasting volcanic events, such as episodes of volcanic unrest, eruptions, and the potential impacts of eruptions. Generally these forecasts are divided into two categories. Short-term forecasts are prepared in response to unrest at volcanoes, rely on geophysical monitoring and related observations, and have the goal of forecasting events on timescales of hours to weeks to provide time for evacuation of people, shutdown of facilities, and implementation of related safety measures. Long-term forecasts are prepared to better understand the potential impacts of volcanism in the future and to plan for potential volcanic activity. Long-term forecasts are particularly useful to better understand and communicate the potential consequences of volcanic events for populated areas around volcanoes and for siting critical infrastructure, such as nuclear facilities. Recent work by an international team, through the auspices of the International Atomic Energy Agency, has focused on developing guidelines for long-term volcanic hazard assessments. These guidelines have now been implemented for hazard assessment for nuclear facilities in nations including Indonesia, the Philippines, Armenia, Chile, and the United States. One any time scale, all volcanic hazard assessments rely on a geologically reasonable conceptual model of volcanism. Such conceptual models are usually built upon years or decades of geological studies of specific volcanic systems, analogous systems, and development of a process-level understanding of volcanic activity. Conceptual models are used to bound potential rates of volcanic activity, potential magnitudes of eruptions, and to understand temporal and spatial trends in volcanic activity. It is these conceptual models that provide essential justification for assumptions made in statistical model development and the application of numerical models to generate quantitative forecasts. It is a

  1. Volcanic ash in ancient Maya ceramics of the limestone lowlands: implications for prehistoric volcanic activity in the Guatemala highlands

    Science.gov (United States)

    Ford, Anabel; Rose, William I.

    1995-07-01

    In the spirit of collaborative research, Glicken and Ford embarked on the problem of identifying the source of volcanic ash used as temper in prehistoric Maya ceramics. Verification of the presence of glass shards and associated volcanic mineralogy in thin sections of Maya ceramics was straightforward and pointed to the Guatemala Highland volcanic chain. Considering seasonal wind rose patterns, target volcanoes include those from the area west of and including Guatemala City. Joint field research conducted in 1983 by Glicken and Ford in the limestone lowlands of Belize and neighboring Guatemala, 300 km north of the volcanic zone and 150 km from the nearest identified ash deposits, was unsuccessful in discovering local volcanic ash deposits. The abundance of the ash in common Maya ceramic vessels coupled with the difficulties of long-distance procurement without draft animals lead Glicken to suggest that ashfall into the lowlands would most parsimoniously explain prehistoric procurement; it literally dropped into their hands. A major archaeological problem with this explanation is that the use of volcanic ash occurring over several centuries of the Late Classic Period (ca. 600-900 AD). To accept the ashfall hypothesis for ancient Maya volcanic ash procurement, one would have to demonstrate a long span of consistent volcanic activity in the Guatemala Highlands for the last half of the first millennium AD. Should this be documented through careful petrographic, microprobe and tephrachronological studies, a number of related archaeological phenomena would be explained. In addition, the proposed model of volcanic activity has implications for understanding volcanism and potential volcanic hazards in Central America over a significantly longer time span than the historic period. These avenues are explored and a call for further collaborative research of this interdisciplinary problem is extended in this paper.

  2. Compositional Differences between Felsic Volcanic rocks from the ...

    African Journals Online (AJOL)

    The elemental and Sr-Nd isotopic compositions of the volcanic rocks suggest that fractional crystallization from differing basic parents accompanied by a limited assimilation (AFC) was the dominant process controlling the genesis of the MER felsic volcanic rocks. Keywords: Ethiopia; Northern Main Ethiopian Rift; Bimodal ...

  3. Assessment of the atmospheric impact of volcanic eruptions

    Science.gov (United States)

    Sigurdsson, H.

    1988-01-01

    The dominant global impact of volcanic activity is likely to be related to the effects of volcanic gases on the Earth's atmosphere. Volcanic gas emissions from individual volcanic arc eruptions are likely to cause increases in the stratospheric optical depth that result in surface landmass temperature decline of 2 to 3 K for less than a decade. Trachytic and intermediate magmas are much more effective in this regard than high-silica magmas, and may also lead to extensive ozone depletion due to effect of halogens and magmatic water. Given the assumed relationship between arc volcanism and subduction rate, and the relatively small variation in global spreading rates in the geologic record, it is unlikely that the rates of arc volcanism have varied greatly during the Cenozoic. Hotspot related basaltic fissure eruptions in the subaerial environment have a higher mass yield of sulfur, but lofting of the valcanic aerosol to levels above the tropopause is required for a climate impact. High-latitude events, such as the Laki 1783 eruption can easily penetrate the tropopause and enter the stratosphere, but formation of a stratospheric volcanic aerosol form low-latitude effusive basaltic eruptions is problematical, due to the elevated low-latitude tropopause. Due to the high sulfur content of hotspot-derived basaltic magmas, their very high mass eruption rates and the episodic behavior, hotspots must be regarded as potentially major modifiers of Earth's climate through the action of their volcanic volatiles on the chemistry and physics of the atmosphere.

  4. Volcanic Ash from the 1999 Eruption of Mount Cameroon Volcano ...

    African Journals Online (AJOL)

    2008-10-21

    Oct 21, 2008 ... fluorine (F) content of the ash was determined by the selective ion electrode method. The results ... the main mineral in volcanic ash responsible for causing silicosis. The F ... volcanic ash with little or no attention to the < 4 µm.

  5. Improving communication during volcanic crises on small, vulnerable islands

    Science.gov (United States)

    McGuire, W. J.; Solana, M. C.; Kilburn, C. R. J.; Sanderson, D.

    2009-05-01

    Increased exposure to volcanic hazard, particularly at vulnerable small islands, is driving an urgent and growing need for improved communication between monitoring scientists, emergency managers and the media, in advance of and during volcanic crises. Information gathering exercises undertaken on volcanic islands (Guadeloupe, St. Vincent and Montserrat) in the Lesser Antilles (eastern Caribbean), which have recently experienced - or are currently experiencing - volcanic action, have provided the basis for the compilation and publication of a handbook on Communication During Volcanic Emergencies, aimed at the principal stakeholder groups. The findings of the on-island surveys point up the critical importance of (1) bringing together monitoring scientists, emergency managers, and representatives of the media, well in advance of a volcanic crisis, and (2), ensuring that procedures and protocols are in place that will allow, as far as possible, effective and seamless cooperation and coordination when and if a crisis situation develops. Communication During Volcanic Emergencies is designed to promote and encourage both of these priorities through providing the first source-book addressing working relationships and inter-linkages between the stakeholder groups, and providing examples of good and bad practice. While targeting the volcanic islands of the eastern Caribbean, the source-book and its content are largely generic, and the advice and guidelines contained therein have equal validity in respect of improving communication before and during crises at any volcano, and have application to the communication issue in respect of a range of other geophysical hazards.

  6. Formation and evolution of mesozoic volcanic basins in Gan-Hang tectonic belt

    International Nuclear Information System (INIS)

    Zhang Xingpu

    1999-01-01

    The author mainly discusses the principle model for the formation and the evolution of Mesozoic volcanic basins in the Gan-Hang Tectonic Belt, and describes the distinct evolution features between the internal and external sites of volcanic basins, the natural relation between the down-warped, down-faulted, collapse volcanic basins and volcanic domes, the relationship between the formation of inter layered fractured zones of the volcanic cover and the evolution of volcanic basins

  7. Explosive Volcanic Activity at Extreme Depths: Evidence from the Charles Darwin Volcanic Field, Cape Verdes

    Science.gov (United States)

    Kwasnitschka, T.; Devey, C. W.; Hansteen, T. H.; Freundt, A.; Kutterolf, S.

    2013-12-01

    Volcanic eruptions on the deep sea floor have traditionally been assumed to be non-explosive as the high-pressure environment should greatly inhibit steam-driven explosions. Nevertheless, occasional evidence both from (generally slow-) spreading axes and intraplate seamounts has hinted at explosive activity at large water depths. Here we present evidence from a submarine field of volcanic cones and pit craters called Charles Darwin Volcanic Field located at about 3600 m depth on the lower southwestern slope of the Cape Verdean Island of Santo Antão. We examined two of these submarine volcanic edifices (Tambor and Kolá), each featuring a pit crater of 1 km diameter, using photogrammetric reconstructions derived from ROV-based imaging followed by 3D quantification using a novel remote sensing workflow, aided by sampling. The measured and calculated parameters of physical volcanology derived from the 3D model allow us, for the first time, to make quantitative statements about volcanic processes on the deep seafloor similar to those generated from land-based field observations. Tambor cone, which is 2500 m wide and 250 m high, consists of dense, probably monogenetic medium to coarse-grained volcaniclastic and pyroclastic rocks that are highly fragmented, probably as a result of thermal and viscous granulation upon contact with seawater during several consecutive cycles of activity. Tangential joints in the outcrops indicate subsidence of the crater floor after primary emplacement. Kolá crater, which is 1000 m wide and 160 m deep, appears to have been excavated in the surrounding seafloor and shows stepwise sagging features interpreted as ring fractures on the inner flanks. Lithologically, it is made up of a complicated succession of highly fragmented deposits, including spheroidal juvenile lapilli, likely formed by spray granulation. It resembles a maar-type deposit found on land. The eruption apparently entrained blocks of MORB-type gabbroic country rocks with

  8. Ash production by attrition in volcanic conduits and plumes.

    Science.gov (United States)

    Jones, T J; Russell, J K

    2017-07-17

    Tephra deposits result from explosive volcanic eruption and serve as indirect probes into fragmentation processes operating in subsurface volcanic conduits. Primary magmatic fragmentation creates a population of pyroclasts through volatile-driven decompression during conduit ascent. In this study, we explore the role that secondary fragmentation, specifically attrition, has in transforming primary pyroclasts upon transport in volcanic conduits and plumes. We utilize total grain size distributions from a suite of natural and experimentally produced tephra to show that attrition is likely to occur in all explosive volcanic eruptions. Our experimental results indicate that fine ash production and surface area generation is fast (eruption column stability, tephra dispersal, aggregation, volcanic lightening generation, and has concomitant effects on aviation safety and Earth's climate.

  9. Explosive volcanism, shock metamorphism and the K-T boundary

    International Nuclear Information System (INIS)

    Desilva, S.L.; Sharpton, V.L.

    1988-01-01

    The issue of whether shocked quartz can be produced by explosive volcanic events is important in understanding the origin of the K-T boundary constituents. Proponents of a volcanic origin for the shocked quartz at the K-T boundary cite the suggestion of Rice, that peak overpressures of 1000 kbars can be generated during explosive volcanic eruptions, and may have occurred during the May, 1980 eruption of Mt. St. Helens. Attention was previously drawn to the fact that peak overpressures during explosive eruptions are limited by the strength of the rock confining the magma chamber to less than 8 kbars even under ideal conditions. The proposed volcanic mechanisms for generating pressures sufficient to shock quartz are further examined. Theoretical arguments, field evidence and petrographic data are presented showing that explosive volcanic eruptions cannot generate shock metamorphic features of the kind seen in minerals at the K-T boundary

  10. Global time-size distribution of volcanic eruptions on Earth.

    Science.gov (United States)

    Papale, Paolo

    2018-05-01

    Volcanic eruptions differ enormously in their size and impacts, ranging from quiet lava flow effusions along the volcano flanks to colossal events with the potential to affect our entire civilization. Knowledge of the time and size distribution of volcanic eruptions is of obvious relevance for understanding the dynamics and behavior of the Earth system, as well as for defining global volcanic risk. From the analysis of recent global databases of volcanic eruptions extending back to more than 2 million years, I show here that the return times of eruptions with similar magnitude follow an exponential distribution. The associated relative frequency of eruptions with different magnitude displays a power law, scale-invariant distribution over at least six orders of magnitude. These results suggest that similar mechanisms subtend to explosive eruptions from small to colossal, raising concerns on the theoretical possibility to predict the magnitude and impact of impending volcanic eruptions.

  11. Assessment of volcanic hazards, vulnerability, risk and uncertainty (Invited)

    Science.gov (United States)

    Sparks, R. S.

    2009-12-01

    A volcanic hazard is any phenomenon that threatens communities . These hazards include volcanic events like pyroclastic flows, explosions, ash fall and lavas, and secondary effects such as lahars and landslides. Volcanic hazards are described by the physical characteristics of the phenomena, by the assessment of the areas that they are likely to affect and by the magnitude-dependent return period of events. Volcanic hazard maps are generated by mapping past volcanic events and by modelling the hazardous processes. Both these methods have their strengths and limitations and a robust map should use both approaches in combination. Past records, studied through stratigraphy, the distribution of deposits and age dating, are typically incomplete and may be biased. Very significant volcanic hazards, such as surge clouds and volcanic blasts, are not well-preserved in the geological record for example. Models of volcanic processes are very useful to help identify hazardous areas that do not have any geological evidence. They are, however, limited by simplifications and incomplete understanding of the physics. Many practical volcanic hazards mapping tools are also very empirical. Hazards maps are typically abstracted into hazards zones maps, which are some times called threat or risk maps. Their aim is to identify areas at high levels of threat and the boundaries between zones may take account of other factors such as roads, escape routes during evacuation, infrastructure. These boundaries may change with time due to new knowledge on the hazards or changes in volcanic activity levels. Alternatively they may remain static but implications of the zones may change as volcanic activity changes. Zone maps are used for planning purposes and for management of volcanic crises. Volcanic hazards maps are depictions of the likelihood of future volcanic phenomena affecting places and people. Volcanic phenomena are naturally variable, often complex and not fully understood. There are

  12. Scenario-based table top simulations

    DEFF Research Database (Denmark)

    Broberg, Ole; Edwards, Kasper; Nielsen, J.

    2012-01-01

    This study developed and tested a scenario-based table top simulation method in a user-driven innovation setting. A team of researchers worked together with a user group of five medical staff members from the existing clinic. Table top simulations of a new clinic were carried out in a simple model...

  13. Experimental results on SUSY searches with top

    CERN Document Server

    Eifert, Till

    2014-01-01

    Searches for supersymmetric partner particles of the top and bottom quarks at the Large Hadron Collider are reviewed. The focus is on the status of searches for a relatively light partner of the top quark performed by the CMS and ATLAS Collaborations. No excess beyond Standard Model expectations is observed and exclusion limits are set on the masses of supersymmetric particles.

  14. Top quark property measurements at the LHC

    CERN Document Server

    Hawkings, Richard; The ATLAS collaboration

    2014-01-01

    Measurements of top quark properties performed at the Large Hadron Collider are reviewed, with a particular emphasis on top-pair charge asymmetries, spin correlations and polarization measurements performed by the ATLAS and CMS collaborations. The measurements are generally in good agreement with predictions from next-to-leading-order QCD calculations, and no deviations from Standard Model expectations have been seen.

  15. Top quark distributions in hadronic collisions

    CERN Document Server

    Frixione, Stefano; Nason, P; Ridolfi, G; Frixione, S; Mangano, M L; Nason, P; Ridolfi, G

    1995-01-01

    We present kinematical distributions for top quark pairs produced at the Tevatron \\ppbar\\ Collider, as predicted within Next-to-Leading-Order QCD. We consider single and double-inclusive distributions, and compare our results to those obtained with the shower Monte Carlo HERWIG. We discuss the implications of our findings for experimental issues such as the measurement of the top quark mass.

  16. Top 12 Web Resources for 2012

    Science.gov (United States)

    Gonzales, Lisa; Vodicka, Devin

    2012-01-01

    In this article, the authors describe some of the top websites recommended by colleagues for the Association of California School Administrators. The Top 12 for 2012 are: (1) Facebook (facebook.com); (2) Twitter (twitter.com); (3) Tungle (tungle.me); (4) FCMAT (fcmat.org); (5) YouSendIt (yousendit.com); (6) Slideshare (slideshare.net); (7) QR…

  17. Latest ATLAS measurements on top quark properties

    CERN Document Server

    Derue, Frederic; The ATLAS collaboration

    2017-01-01

    The top quark is unique among the known quarks in that it decays before it has an opportunity to form hadronic bound states. This makes measurements of its properties particularly interesting as one can access directly the properties of a bare quark. The latest measurements of these properties with the ATLAS detector at the LHC are presented using 8 TeV and 13 TeV data, excluding results from single top production. Measurements of top quark spin observables in top-antitop events, each sensitive to a different coefficient of the spin density matrix, are presented and compared to the Standard Model predictions. The helicity of the W boson from the top decays and the production angles of the top quark are further discussed. New results on the measurment of color flow effects in $t{\\bar t}$ events are presented. Limits on the rate of flavour changing neutral currents in the production or decay of the top quark are reported. The cross-section measurement of photons produced in association with top-quark pairs is a...

  18. Thermal design of top shield for PFBR

    International Nuclear Information System (INIS)

    Gajapathy, R.; Jalaludeen, S.; Selvaraj, A.; Bhoje, S.B.

    1988-01-01

    India's Liquid Metal Cooled Fast Breeder Reactor programme started with the construction of loop type 13MW(e) Fast Breeder Test Reactor (FBTR) which attained criticality in October 1985. With the experience of FBTR, the design work on pool type 500 MW(e) Prototype Fast Breeder Reactor (PFBR) which will be a forerunner for future commercial fast breeder reactors, has been started. The Top Shield forms the cover for the main vessel which contains the primary circuit. Argon cover gas separates the Top Shield from the free level of hot sodium pool (803K). The Top Shield which is of box type construction consists of control plug, two rotatable plugs and roof slab, assembled together, which provide biological shielding, thermal shielding and leak tight containment at the top of the main vessel. Heat is transferred from the sodium pool to the Top Shield through argon cover gas and through components supported by it and dipped in the sodium pool. The Top Shield should be maintained at the desired operating temperature by incorporating a cooling system inside it. Insulation may be provided below the bottom plate to reduce the heat load to the cooling system, if required. The thermal design of Top Shield consists of estimation of heat transfer to the Top Shield, selection of operating temperature, assessment of insulation requirement, design of cooling system and evaluation of transient temperature changes

  19. SWFSC/MMTD/CCE: Tagging and Tracking of Physeter (T-TOP/T-TOP2) 1997

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This research was devoted to studying sperm whale (Physeter macrocephalus) behavior. The principal study area for T-TOP and T-TOP2 was the Pioneer Seamount, 50...

  20. Measuring top-quark polarization in top-pair + missing-energy events.

    Science.gov (United States)

    Berger, Edmond L; Cao, Qing-Hong; Yu, Jiang-Hao; Zhang, Hao

    2012-10-12

    The polarization of a top quark can be sensitive to new physics beyond the standard model. Since the charged lepton from top-quark decay is maximally correlated with the top-quark spin, it is common to measure the polarization from the distribution in the angle between the charged lepton and the top-quark directions. We propose a novel method based on the charged lepton energy fraction and illustrate the method with a detailed simulation of top-quark pairs produced in supersymmetric top squark pair production. We show that the lepton energy ratio distribution that we define is very sensitive to the top-quark polarization but insensitive to the precise measurement of the top-quark energy.

  1. The operational eEMEP model version 10.4 for volcanic SO2 and ash forecasting

    Science.gov (United States)

    Steensen, Birthe M.; Schulz, Michael; Wind, Peter; Valdebenito, Álvaro M.; Fagerli, Hilde

    2017-05-01

    concentrations with more certainty for forecast or scientific analysis purposes, a finer resolution is needed. The model is further developed to simulate ash from highly explosive eruptions. A possibility of increasing the number of vertical layers, achieving finer vertical resolution, as well as a higher model top, is included in the eEMEP version. Ash size distributions may be altered for different volcanic eruptions and assumptions. Since ash particles are larger than typical particles in the standard model, gravitational settling across all vertical layers is included. We attempt finally a specific validation of the simulation of ash and its vertical distribution. Model simulations with and without gravitational settling for the 2010 Eyjafjallajökull eruption are compared to lidar observations over central Europe. The results show that with gravitation the centre of the ash mass can be 1 km lower over central Europe than without gravitation. However, the height variations in the ash layer caused by real weather situations are not captured perfectly well by either of the two simulations, playing down the role of gravitation parameterization imperfections. Both model simulations have on average an ash centre of mass below the observed values. Correlations between the observed and corresponding model centres of mass are higher for the model simulation with gravitational settling for four of the six stations studied here. The inclusion of gravitational settling is suggested to be required for a volcanic ash model.

  2. Classifcation of volcanic structure in mesozoic era in the Fuzhou-Shaoxing area

    International Nuclear Information System (INIS)

    Zhang Fengqi.

    1989-01-01

    The volcanic structure in the Fuzhou-Shaoxing area can be classified into IV grades: the grade I be the zone of volcanic activity; the grade II be the second zone of volcanic activity; the grade III be the positive, negative volcanic structure; the grade IV be volcanic conduit, volcanic crater, concealed eruption breccia pipe. Based on the geological situation in this area, the different types of volcanic structure are also dealt with. In the mean time, both the embossed type in the depression area and the depressed type in the embossed area in the volcanic basin are pointed out. It is of great advantage to Uranium mineralization

  3. Volcanic sulfur dioxide index and volcanic explosivity index inferred from eruptive volume of volcanoes in Jeju Island, Korea: application to volcanic hazard mitigation

    Science.gov (United States)

    Ko, Bokyun; Yun, Sung-Hyo

    2016-04-01

    Jeju Island located in the southwestern part of Korea Peninsula is a volcanic island composed of lavaflows, pyroclasts, and around 450 monogenetic volcanoes. The volcanic activity of the island commenced with phreatomagmatic eruptions under subaqueous condition ca. 1.8-2.0 Ma and lasted until ca. 1,000 year BP. For evaluating volcanic activity of the most recently erupted volcanoes with reported age, volcanic explosivity index (VEI) and volcanic sulfur dioxide index (VSI) of three volcanoes (Ilchulbong tuff cone, Songaksan tuff ring, and Biyangdo scoria cone) are inferred from their eruptive volumes. The quantity of eruptive materials such as tuff, lavaflow, scoria, and so on, is calculated using a model developed in Auckland Volcanic Field which has similar volcanic setting to the island. The eruptive volumes of them are 11,911,534 m3, 24,987,557 m3, and 9,652,025 m3, which correspond to VEI of 3, 3, and 2, respectively. According to the correlation between VEI and VSI, the average quantity of SO2 emission during an eruption with VEI of 3 is 2-8 × 103 kiloton considering that the island was formed under intraplate tectonic setting. Jeju Island was regarded as an extinct volcano, however, several studies have recently reported some volcanic eruption ages within 10,000 year BP owing to the development in age dating technique. Thus, the island is a dormant volcano potentially implying high probability to erupt again in the future. The volcanoes might have explosive eruptions (vulcanian to plinian) with the possibility that SO2 emitted by the eruption reaches stratosphere causing climate change due to backscattering incoming solar radiation, increase in cloud reflectivity, etc. Consequently, recommencement of volcanic eruption in the island is able to result in serious volcanic hazard and this study provides fundamental and important data for volcanic hazard mitigation of East Asia as well as the island. ACKNOWLEDGMENTS: This research was supported by a grant [MPSS

  4. Top quark mass measurement in dilepton channel

    International Nuclear Information System (INIS)

    Lysak, R.

    2007-01-01

    In this work, we measured the top quark mass in tt'-' events produced in pp'-' interactions at the center-of-mass energy 1.96 TeV using CDF detector. We used dilepton in tt'-' events where both W bosons from top quarks are decaying into leptons. The data sample corresponds to 340 pb -1 . We found there 33 tt'-' candidates while expecting 10.5 ± 1.9 background events. In the measurement, we reconstruct one, representative mass for each event using the assumption about longitudinal momentum of in tt'-' system, in order to be able to kinematically solve the under-constrained system. The mass distributions (templates) are created for simulated signal and background events. Templates are parametrized in order to obtain smooth probability density functions. Likelihood maximization which includes these parametrized templates is then performed on reconstructed masses obtained from data sample in order to obtain final top quark mass estimate. The result of applying this procedure on data events is top quark mass estimate 169.5 +7. 7 - 7.2 (stat.) ± 4.0(syst.) GeV/c 2 for 30 out of 33 candidates, where the solution for top quark mass was found. This measurement was a part of first top quark mass measurement in dilepton channel at CDF in Run II. The top quark mass measured here is consistent with the CDF measurement in dilepton channel from Run I M top = 167.4 ± 10.3(stat.) ± 4.8(syst.) GeV/c 2 . Moreover, the combined result of four top quark mass measurements in dilepton channel from Run II (one of these four measurements is our measurement) M top = 167.9 ± 5.2(stat.) ± 3.7(syst.) GeV/c 2 significantly (by ∼ 40%) improved the precision of top quark mass determination from Run I. It should be also noted, that this combined result is consistent with measurement obtained in 'lepton+jets' channel at CDF in Run II (M top = 173.5 +3.9 -3.8 GeV/c 2 ). So, we don't have yet any indication about new physics beyond the Standard Model. My main contribution in this analysis was

  5. Evidence for sub-lacustrine volcanic activity in Lake Bolsena (central Italy) revealed by high resolution seismic data sets

    Science.gov (United States)

    Lindhorst, Katja; Krastel, Sebastian; Wagner, Bernd; Schuerer, Anke

    2017-06-01

    The Bolsena caldera that formed between 0.6 and 0.2 Ma has a well preserved structural rim, which makes it an ideal site to study the tectonic and volcanic evolution of calderas. However, the main area is covered by a 150 m deep lake which makes it rather difficult to investigate the subsurface structure directly. To overcome this problem new high resolution hydro-acoustic surveys using a multichannel reflection seismic system and a sediment echo-sounder system were conducted in September 2012. As space was limited we used a rowing boat towed by a rubber boat to handle a 36 m long and 24 channel streamer to receive seismic reflections produced using a Mini GI-Gun (0.25 l). The subsurface structure of Lake Bolsena was imaged up to a sediment depth of 190 m, which is estimated to have filled over a period of 333 kyrs. However, massive pyroclastic flow deposits found in the deeper parts of the basin indicate an initial infill of volcanic deposits from two adjacent younger calderas, the Latera (W) and Montefiascone (SE) calderas. Our data suggest that the caldera has a long history of active volcanism, because the lacustrine sediments show post-sedimentary influences of geothermal fluids. We mapped several mound structures at various stratigraphic depths. Two volcanic structures outcrop at the modern lake surface implying recent activity. One of these structures is hardly covered by sediments and has a crater-like feature in its summit. The other structure shows a pockmark-like depression on top. Another observable feature is a partially sediment filled crater located in the western part of the lake which further implies the existence of a magma chamber located beneath the Bolsena caldera. Since the late Pleistocene and Holocene, the sedimentation was mainly hemipelagic evidenced by a sediment drape of up to 10 m thick sediment drape on the uppermost sediments. Beneath the drape we found evidence for a distal tephra layer likely related to an explosive eruption from

  6. Volcanism in the Sumisu Rift. Pt. 2

    International Nuclear Information System (INIS)

    Hochstaedter, A.G.; Gill, J.B.; Morris, J.D.

    1990-01-01

    A bimodal suite of volcanic rocks collected from the Sumisu Rift by ALVIN provide present day example of the first magmatic products of arc rifting during the initiation of back-arc spreading. The trace element and isotopic composition of these rocks, which are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, differ from those of arc rocks and N-MORB in their relative incorporation of both subduction-related and non-subduction-related components. Subduction-related components, i.e., those that distinguish volcanic arc basalts from N-MORB, are less pronounced in rift lavas than in arc lavas. Alkali and alkaline earth to high field strength element and REE ratios as well as 87 Sr/ 86 Sr are intermediate between those of N-MORB and Izu arc lavas and indicate that Sumisu Rift basalts are similar to BABB erupted in other, more mature back-arc basins. These results show that back-arc basins may begin their magmatic evolution with BABB rather than more arc-like lavas. Evidence of non-subduction related components remains after the effects of subduction related components are removed or accounted for. Compared to the arc, higher HFSE and REE concentrations, contrasting REE patterns, and ≤ε Nd in the rift reflect derivation of rift lavas from more enriched components. Although SR basalt resembles E-MORB in many trace element ratios, it is referred to as BABB because low concentrations of Nb are similar to those in volcanic arcs and H 2 O/REE and H 2 O/K 2 O exceed those of E-MORB. Differences in HREE pattern and ε Nd require that the E-MORB characteristics result from source heterogeneities and not lower degrees of melting. Enriched mantle beneath the rift may reflect enriched blobs entrained in a more depleted matrix, or injection of new, more enriched mantle. High 208 Pb/ 204 Pb and moderate 207 Pb/ 204 Pb ratios with respect to Pacific MORB also reflect ancient mantle enrichment. (orig.)

  7. Top quark studies with the ATLAS detector

    CERN Document Server

    Capua, Marcella; The ATLAS collaboration

    2015-01-01

    The latest top quark studies in proton-proton collisions at a centre-of-mass energy of 7 and 8 TeV with the ATLAS detector are reported. We present recent results on the top pair production inclusive cross-sections, top pair production differential cross-section in the resolved and boosted regimes, single top-quark production cross-sections measured in the t-channel, s-channel and W-boson associated processes, as well as the CKM matrix element $|V_{tb}|$ determination. The results are compared with theoretical expectations. Latest ATLAS results on top properties will be also shown in terms of direct and mass pole, spin correlations and charge asymmetry.

  8. Top quark studies with the ATLAS detector

    CERN Document Server

    Capua, Marcella; The ATLAS collaboration

    2015-01-01

    The latest studies of top quark production measurement in proton-proton collisions at a centre-of-mass energy of 7 and 8 TeV with the ATLAS detector are reported. The talk will present recent results on the top pair production inclusive cross sections, top pair production differential cross section in resolved and boosted regime, single top-quark productions cross sections measured for t-channel, s-channel and W-boson associated processes. as well as d the CKM matrix element |Vtb| determination. All the results are compared with theoretical expectations. Latest ATLAS results on top mass measurements will be also shown in terms of direct and mass pole results.

  9. TOP500 Supercomputers for June 2002

    Energy Technology Data Exchange (ETDEWEB)

    Strohmaier, Erich; Meuer, Hans W.; Dongarra, Jack; Simon, Horst D.

    2002-06-20

    19th Edition of TOP500 List of World's Fastest Supercomputers Released MANNHEIM, Germany; KNOXVILLE, Tenn.;&BERKELEY, Calif. In what has become a much-anticipated event in the world of high-performance computing, the 19th edition of the TOP500 list of the worlds fastest supercomputers was released today (June 20, 2002). The recently installed Earth Simulator supercomputer at the Earth Simulator Center in Yokohama, Japan, is as expected the clear new number 1. Its performance of 35.86 Tflop/s (trillions of calculations per second) running the Linpack benchmark is almost five times higher than the performance of the now No.2 IBM ASCI White system at Lawrence Livermore National Laboratory (7.2 Tflop/s). This powerful leap frogging to the top by a system so much faster than the previous top system is unparalleled in the history of the TOP500.

  10. Top quark production at the LHC

    CERN Document Server

    Ferreira da Silva, Pedro

    2016-01-01

    Twenty years past its discovery, the top quark continues attracting great interest as experiments keep unveiling its properties. An overview of the latest measurements in the domain of top quark production, performed by the ATLAS and CMS experiments at the CERN LHC, is given. The latest measurements of top quark production rates via strong and electroweak processes are reported and compared to different perturbative QCD predictions. Fundamental properties, such as the mass or the couplings of the top quark, as well as re-interpretations seeking for beyond the standard model contributions in the top quark sector, are extracted from these measurements. In each case an attempt to highlight the first results and main prospects for the on-going Run 2 of the LHC is made.

  11. D OE top quark mass analysis

    International Nuclear Information System (INIS)

    Strovink, M.

    1995-07-01

    Based on (44-48 pb -1 ) of lepton + jets data, we review D0's initial analysis of the top quark mass. The result, M top = 199 ± 19/21 (stat.) ± 22 (syst.) GeV/c 2 , is insensitive to background normalization. The errors are based on ISAJET top Monte Carlo, with its more severe gluon radiation, and allow for ISAJET/HERWIG differences. Good progress is being made in reducing the systematic error. We present a new study based on two-dimensional distributions of reconstructed top quark vs. dijet mass. With 98.7% confidence we observe a peak in the top mass - dijet mass plane. The peak and its projections are similar both in shape and magnitude to expectations based on the decay sequence 1 → bW, W → jj

  12. Top quark production at the LHC (single top and tt-bar cross sections)

    International Nuclear Information System (INIS)

    Lange, J.

    2014-01-01

    With the large number of top quarks produced at the LHC, top quark physics enters an era of precision and properties measurements. This article reviews the recent advances in top quark cross section measurements performed by ATLAS and CMS using data recorded in 2011 with integrated luminosities up to 5 fb -1 . They include precision inclusive cross sections, the establishment of challenging channels, first differential cross section measurements and single top production. An overall good agreement with Standard Model predictions is observed

  13. Measurements and searches with top quarks

    International Nuclear Information System (INIS)

    Peters, Reinhild Yvonne

    2008-01-01

    In 1995 the last missing member of the known families of quarks, the top quark, was discovered by the CDF and D0 experiments at the Tevatron, a proton-antiproton collider at Fermilab near Chicago. Until today, the Tevatron is the only place where top quarks can be produced. The determination of top quark production and properties is crucial to understand the Standard Model of particle physics and beyond. The most striking property of the top quark is its mass--of the order of the mass of a gold atom and close to the electroweak scale--making the top quark not only interesting in itself but also as a window to new physics. Due to the high mass, much higher than of any other known fermion, it is expected that the top quark plays an important role in electroweak symmetry breaking, which is the most prominent candidate to explain the mass of particles. In the Standard Model, electroweak symmetry breaking is induced by one Higgs field, producing one additional physical particle, the Higgs boson. Although various searches have been performed, for example at the Large Electron Positron Collider (LEP), no evidence for the Higgs boson could yet be found in any experiment. At the Tevatron, multiple searches for the last missing particle of the Standard Model are ongoing with ever higher statistics and improved analysis techniques. The exclusion or verification of the Higgs boson can only be achieved by combining many techniques and many final states and production mechanisms. As part of this thesis, the search for Higgs bosons produced in association with a top quark pair (t(bar t)H) has been performed. This channel is especially interesting for the understanding of the coupling between Higgs and the top quark. Even though the Standard Model Higgs boson is an attractive candidate, there is no reason to believe that the electroweak symmetry breaking is induced by only one Higgs field. In many models more than one Higgs boson are expected to exist, opening even more channels

  14. Volcanism Studies: Final Report for the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce M. Crowe; Frank V. Perry; Greg A. Valentine; Lynn M. Bowker

    1998-12-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is

  15. Tungsten abundances in some volcanic rocks

    International Nuclear Information System (INIS)

    Helsen, J.N.; Shaw, D.M.; Crocket, J.H.

    1978-01-01

    A radiochemical N.A.A. method was used to obtain new values on W distribution in some 125 volcanic rocks, mainly basalts and andesites, from different petrotectonic environments. These W data are below previously reported abundances. New median values in various types of rocks are suggested (ppm W). Basalts: ocean floor, 0.15; ocean islands subalkaline, 0.28; ocean islands alkaline, 0.60; island arc, 0.19; continental margin, 0.40; continental subalkaline, 0.30; continental alkaline, 1.35. Andesites: island arc, 0.23; continental margin, 1.05. Median values for all 91 basalts and all 20 andesites are 0.36 and 0.29 ppm respectively. (author)

  16. Inside the volcanic boiler room: knowledge exchange among stakeholders of volcanic unrest

    Science.gov (United States)

    Gottsmann, Joachim; Christie, Ryerson; Bretton, Richard

    2014-05-01

    The knowledge of the causative links between subsurface processes, resulting monitoring signals and imminent eruption is incomplete. As a consequence, hazard assessment and risk mitigation strategies are subject to uncertainty. Discussion of unrest and pre-eruptive scenarios with uncertain outcomes are central during the discourse between a variety of stakeholders in volcanic unrest including scientists, emergency managers, policy makers and the public. Drawing from research within the EC FP7 VUELCO project, we argue that knowledge exchange amongst the different stakeholders of volcanic unrest evolves along three dimensions: 1) the identification of knowledge holders (including local communities) and their needs and expectations, 2) vehicles of communication and 3) trust. In preparing products that feed into risk assessment and management, scientists need to ensure that their deliverables are timely, accurate, clear, understandable and cater to the expectations of emergency managers. The means and content of communication amongst stakeholders need to be defined and adhered to. Finally, efficient and effective interaction between stakeholders is ideally based on mutual trust between those that generate knowledge and those that receive knowledge. For scientists, this entails contextualising volcanic hazard and risk in the framework of environmental and social values. Periods of volcanic quiescence are ideally suited to test established protocols of engagement between stakeholders in preparation for crises situations. The different roles of stakeholders and associated rules of engagement can be scrutinised and reviewed in antecessum rather than ad-hoc during a crisis situation to avoid issues related to distrust, loss of credibility and overall poor risk management. We will discuss these themes drawing from exploitation of research results from Mexico and Ecuador.

  17. The monogenetic Bayuda Volcanic Field, Sudan - New insights into geology and volcanic morphology

    Science.gov (United States)

    Lenhardt, Nils; Borah, Suranjana B.; Lenhardt, Sukanya Z.; Bumby, Adam J.; Ibinoof, Montasir A.; Salih, Salih A.

    2018-05-01

    The small monogenetic Bayuda Volcanic Field (BVF; 480 km2), comprising at least 53 cinder cones and 15 maar volcanoes in the Bayuda desert of northern Sudan is one of a few barely studied volcanic occurrences of Quaternary age in Sudan. The exact age of the BVF and the duration of volcanic activity has not yet been determined. Furthermore, not much is known about the eruptional mechanisms and the related magmatic and tectonic processes that led to the formation of the volcanic field. In the framework of a larger project focusing on these points it is the purpose of this contribution to provide a first account of the general geology of the BVF volcanoes as well as a first description of a general stratigraphy, including a first description of their morphological characteristics. This was done by means of fieldwork, including detailed rock descriptions, as well as the analysis of satellite images (SRTM dataset at 30 m spatial resolution). The BVF cinder cones are dominated by scoracious lapilli tephra units, emplaced mainly by pyroclastic fallout from Strombolian eruptions. Many cones are breached and are associated with lava flows. The subordinate phreatomagmatism represented by maar volcanoes suggests the presence of ground and/or shallow surface water during some of the eruptions. The deposits constituting the rims around the maar volcanoes are interpreted as having mostly formed due to pyroclastic surges. Many of the tephra rings around the maars are underlain by thick older lava flows. These are inferred to be the horizons where rising magma interacted with groundwater. The existence of phreatomagmatic deposits may point to a time of eruptive activity during a phase with wetter conditions and therefore higher groundwater levels than those encountered historically. This is supported by field observations as well as the morphological analysis, providing evidence for relatively high degrees of alteration of the BVF volcanoes and therefore older eruption ages as

  18. Discovery of single top quark production

    Energy Technology Data Exchange (ETDEWEB)

    Gillberg, Dag [Simon Fraser Univ., Burnaby, BC (Canada)

    2009-04-01

    The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking - the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. An analysis is performed using 2.3 fb-1 of data recorded by the D0 detector at the Fermilab Tevatron Collider at centre-of-mass energy √s = 1.96 TeV. Boosted decision trees are used to isolate the single top signal from background, and the single top cross section is measured to be σ(p$\\bar{p}$ → tb + X, tqb + X) = 3.74-0.74+0.95 pb. Using the same analysis, a measurement of the amplitude of the CKM matrix element Vtb, governing how top and b quarks mix, is also performed. The measurement yields: |V{sub tb}|f1L| = 1.05 -0.12+0.13, where f1L is the left-handed Wtb coupling. The separation of signal from background is improved by combining the boosted decision trees with two other multivariate techniques. A new cross section measurement is performed, and the significance for the excess over the predicted background exceeds 5

  19. Volcanic glasses, their origins and alteration processes

    Science.gov (United States)

    Friedman, I.; Long, W.

    1984-01-01

    Natural glass can be formed by volcanic processes, lightning (fulgarites) burning coal, and by meteorite impact. By far the most common process is volcanic - basically the glass is rapidly chilled molten rock. All natural glasses are thermodynamically unstable and tend to alter chemically or to crystallize. The rate of these processes is determined by the chemical composition of the magma. The hot and fluid basaltic melts have a structure that allows for rapid crystal growth, and seldom forms glass selvages greater than a few centimeters thick, even when the melt is rapidly cooled by extrusion in the deep sea. In contrast the cooler and very viscous rhyolitic magmas can yield bodies of glass that are tens of meters thick. These highly polymerized magmas have a high silica content - often 71-77% SiO2. Their high viscosity inhibits diffusive crystal growth. Basalt glass in sea water forms an alteration zone called palagonite whose thickness increases linearly with time. The rate of diffusion of water into rhyolitic glass, which follows the relationship - thickness = k (time) 1 2, has been determined as a function of the glass composition and temperature. Increased SiO2 increases the rate, whereas increased CaO, MgO and H2O decrease the rate. The activation energy of water diffusion varies from about 19 to 22 kcal/mol. for the glasses studied. The diffusion of alkali out of rhyolite glass occurs simultaneously with water diffusion into the glass. The rate of devitrification of rhyolitic glass is a function of the glass viscosity, which in turn is a function of water content and temperature. Although all of the aforementioned processes tend to destroy natural glasses, the slow rates of these processes, particularly for rhyolitic glass, has allowed samples of glass to persist for 60 million years. ?? 1984.

  20. Detecting Volcanic Ash Plumes with GNSS Signals

    Science.gov (United States)

    Rainville, N.; Larson, K. M.; Palo, S. E.; Mattia, M.; Rossi, M.; Coltelli, M.; Roesler, C.; Fee, D.

    2016-12-01

    Global Navigation Satellite Systems (GNSS) receivers are commonly placed near volcanic sites to measure ground deformation. In addition to the carrier phase data used to measure ground position, these receivers also record Signal to Noise ratio (SNR) data. Larson (2013) showed that attenuations in SNR data strongly correlate with ash emissions at a series of eruptions of Redoubt Volcano. This finding has been confirmed at eruptions for Tongariro, Mt Etna, Mt Shindake, and Sakurajima. In each of these detections, very expensive geodetic quality GNSS receivers were used. If low-cost GNSS instruments could be used instead, a networked array could be deployed and optimized for plume detection and tomography. The outputs of this sensor array could then be used by both local volcanic observatories and Volcano Ash Advisory Centers. Here we will describe progress in developing such an array. The sensors we are working with are intended for navigation use, and thus lack the supporting power and communications equipment necessary for a networked system. Reliably providing those features is major challenge for the overall sensor design. We have built prototypes of our Volcano Ash Plume Receiver (VAPR), with solar panels, lithium-ion batteries and onboard data storage for preliminary testing. We will present results of our field tests of both receivers and antennas. A second critical need for our array is a reliable detection algorithm. We have tested our algorithm on data from recent eruptions and have incorporated the noise characteristics of the low-cost GNSS receiver. We have also developed a simulation capability so that the receivers can be deployed to optimize vent crossing GNSS signals.