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Dual Plane Piv Investigation of Acoustically Excited Jets in a Swi...

By: J. M. Rees; W. B. Zimmerman; G. S. Regunath

Description: Department of Aeronautical and Automotive Engineering, Stewart Miller Building, Loughborough University, Leicestershire LE11 3TU, UK. A novel dual-plane dye laser PIV technique used to analyze helicity and energy dissipation in an unexcited turbulent swirling jet of pressurized cold air has established that regions within the flow field of the jet exhibiting high helicity are correlated with regions of high turbulent kinetic energy dissipation. This PIV ...

André, J. C. and Lesieur, M.: Influence of helicity on the evolution of isotropic turbulence at high Reynolds number, J. Fluid Mech., 81, 187–207, 1977.; Crow, S. C. and Champagne, F. H.: Orderly structure in jet turbulence, J. Fluid Mech., 48, 547–591, 1971.; Drobniak, S. and Klajny, R.: Coherent structures of free acoustically stimulated jet, J. Turbulence, 3, 001, doi:10.1088/1468-5248/3/1/001, 2002.; Khomenko, G...

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Manifestation of Nonlinear Elasticity in Rock: Convincing Evidence...

By: P. N. J. Rasolofosaon; P. A. Johnson

Description: Los Alamos National Laboratory, Los Alamos, New Mexiko. Nonlinear elastic response in rock is established as a robust and representative characteristic rock rather than a curiosity. We show measurements of this behaviour from a variety of experiments on rock taken over many orders of magnitude in strain and frequency. The evidence leads to a pattern of unifying behaviour in rock: (1) Nonlinear response in rock is...

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Landau-fluid Simulations of Alfvén-wave Instabilities in a Warm Co...

By: P. L. Sulem; T. Passot; G. Bugnon

Description: CNRS, Observatoire de la Côte d’Azur, B.P. 4229, 06304 Nice Cedex 4, France. A dispersive Landau-fluid model is used to study the decay and modulational instabilities of circularly-polarized Alfvén waves in a collisionless plasma, as well as their nonlinear developments. Comparisons are presented with the drift-kinetic approximation for the dispersionless regime and with hybrid simulations in more general conditions. The effect of the nature of the inst...

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Projection of Compact Fractal Sets: Application to Diffusion-limit...

By: F. Maggi

Description: Berkeley Water Center, Civil and Environmental Engineering, 413 O'Brien Hall, University of California, Berkeley, CA 94720-1710, USA. The need to assess the three-dimensional fractal dimension of fractal aggregates from the fractal dimension of two-dimensional projections is very frequent in geophysics, soil, and atmospheric sciences. However, a generally valid approach to relate the two- and three-dimensional fractal dimensions is missing, thus question...

Coleman P. and Pietronero L.: The fractal structure of the Universe, Phys. Rep. 213, 311–389, 1992.; Friedlander S. K.: Smoke, Dust and Haze, fundamentals of aerosol behavior. Wiler, New York, 1977.; Grassberger H. G. E. and Procaccia I.: Characterization of strange attractors, Phys. Rev. Lett. 50(5), 346–349, 1983.; Hunt B. R. and Kaloshin V. Y.: How projections affect the dimension spectrum of fractal measures, Nonlinearity 10, 1031–1046, 1997.; Kranenburg C.: On the f...

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Synchronicity as an Essential Property of Solar–terrestrial Relati...

By: V. A. Tartakovsky

Description: Institute of Monitoring of Climatic and Ecological Systems SB RAS, Tomsk, Russia. It is assumed that external forcing synchronizes processes initiated by it. The concept of the synchronicity of processes is defined, based on their essential signs. The processes under study are decomposed on latent orthogonal components, which differ because of the coincidence and non-coincidence of the essential signs. The information from the original da...

Lyubushin, A. A.: Analiz dannyh sistem geofizicheskogo i ekologicheskogo monitoringa, Nauka, Moskva, 2007.; Met Office Hadley Centre Observations Datasets: available at: http://www.metoffice.gov.uk/hadobs/crutem4/data/download.html, last access: 17 June 2015.; Alekseev, G. V., Luk'janova, R. Ju., and Ivanov, T. E.: Vlijanie fluktuacij i izmenenij solnechnoj aktivnosti na harakteristiki klimata vyso...

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Non-gaussian Statistics in Space Plasma Turbulence: Fractal Proper...

By: T. Dudok De Wit; V. V. Krasnosel'Skikh

Description: Centre de Physique Théorique, CNRS and Université de Provence, Luminy case 907, 13288 Marsaille cédex 9, France. Statistical properties of collisionless plasmas in the vicinity of the Earth's bow shock are investigated with the aim to characterize the intermittent behaviour of non- magnetohydrodynamic turbulence. The structure functions of the fluctuating magnetic field reveal an increasing departure from Gaussianity at...

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Large- and Small-scale Turbulent Spectra in Mhd and Atmospheric Fl...

By: A. Eidelman; E. Golbraikh; O. G. Chkhetiani

Description: Space Research Institute, Russian Academy of Sciences, Profsoyuznaya str., 84/32 Moscow 117810, Russia. In the present review we discuss certain studies of large- and small-scale turbulent spectra in MHD and atmospheric flows performed by S. S. Moiseev and his co-authors during the last years of his life and continued by his co-authors after he passed away. It is shown that many ideas developed in these works have not lost their novelty and urgency until...

Alemany, A., Moreau, R., Sulem, P. L., and Frisch, U.: Influence of an external magnetic field on homogeneous MHD turbulence, J. de Mecanique, 18, 277–313, 1979.; Batchelor, G. K.: Computation of the energy spectrum in homogeneous two-dimensional turbulence, Phys. Fluids, 12, 233–239, 1969.; Belyan, A. V., Moiseev, S. S., and Chkhetiani, O. G.: On eddy viscosity in helical turbulence, Physics – Doklady, 39, 13–15, 1994.; Belyan, A. V., Golbraikh, E. I., Moiseev, S. S., a...

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Contribution of 3-d Electrical Resistivity Tomography for Landmine...

By: G. El-qady; A. Taha; J. Matsushima; M. Metwaly; S. Szalai; N. S. N. Al-arifi

Description: National Research Institute of Astronomy and Geophysics (NRIAG), 11722 Helwan, Cairo, Egypt. Landmines are a type of inexpensive weapons widely used in the pre-conflicted areas in many countries worldwide. The two main types are the metallic and non-metallic (mostly plastic) landmines. They are most commonly investigated by magnetic, ground penetrating radar (GPR), and metal detector (MD) techniques. These geophysical techniques however have significant ...

% vor jede Referenz Alaia, R., Patella, D., and Mauriello, P.: Applied of geoelectrical 3-D probability tomography in a test-site of the archeological park of Pompei, J. Geophys. Eng., 5, 67–76, 2008.; % vor jede Referenz Benderitter, Y., Jolivet, A., Mounir, A., and Tabbagh, A.: Application of the electrostatic quadripole to sounding in the hectometric depth range, J. Appl. Geophys., 31, 1–6, 1994.; % vor jede Referenz Berhe, A. A.: The contribution of Landmines to land...

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Solute Transport in a Heterogeneous Aquifer: a Search for Nonlinea...

By: T. Harter; H. Zhang; B. Sivakumar

Description: Department of Land, Air and Water Resources, University of California, Davis, USA. The potential use of a nonlinear deterministic framework for understanding the dynamic nature of solute transport processes in subsurface formations is investigated. Time series of solute particle transport in a heterogeneous aquifer medium, simulated using an integrated probability/Markov chain (TP/MC) model, groundwater flow model, and particle transport model, are stud...

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Successive Bifurcations in a Shallow-water Model Applied to the Wi...

By: M. Ghil; H. Dijkstra; S. Speich

Description: Climate - the "coarse-gridded" state of the coupled ocean - atmosphere system - varies on many time and space scales. The challenge is to relate such variation to specific mechanisms and to produce verifiable quantitative explanations. In this paper, we study the oceanic component of the climate system and, in particular, the different circulation regimes of the mid-latitude win driven ocean on the interannual time scale. These circulations are dominate...

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Neural-network-based Prediction Techniques for Single Station Mode...

By: T. D. Xenos

Description: Aristotelian University of Thessaloniki, Dept of Electrical and Computers Eng., 54006 Thessaloniki, Greece. In this work, Neural-Network-based single-station hourly daily foF2 and M(3000)F2 modelling of 15 European ionospheric stations is investigated. The data used are neural networks and hourly daily values from the period 1964- 1988 for training the neural networks and from the period 1989-1994 for checking the prediction accura...

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The Dynamics of Electron and Ion Holes in a Collisionless Plasma :...

By: P. K. Shukla; B. Eliasson

Description: Institut für Theoretische Physik IV, Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, Germany. We present a review of recent analytical and numerical studies of the dynamics of electron and ion holes in a collisionless plasma. The new results are based on the class of analytic solutions which were found by Schamel more than three decades ago, and which here work as initial conditions to numerical simulations of the dynamics o...

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Nonlinear Analysis of Magnitude and Interevent Time Interval Seque...

By: T. Matcharashvili; T. Chelidze; Z. Javakhishvili

Description: Institute of Geophysics, Georgian A. Sci. I, Alexidze str. 380093 Tbilisi, Georgia. It is well known that lithospheric seismic processes are characterized by self-similarity or scale invariance in terms of earthquake-size, time, space and space-time distributions, although precise details of underlying dynamics are not clear. In this study we apply nonlinear dynamics theory tools, such as a correlation dimension, "surrogate" data analysis and positive L...

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Periodic and Homoclinic Orbits in a Toy Climate Model : Volume 1, ...

By: M. Toner; A. D. Kirwan, Jr.

Description: Dept. of Mathematics and Statistics, Old Dominion University, Norfolk, Virginia, USA. A two dimensional system of autonomous nonlinear ordinary differential equations models glacier growth and temperature changes on an idealized planet. We apply standard perturbative techniques from dynamical systems theory to study small amplitude periodic orbits about a constant equilibrium. The equations are put in cononical form and the local phase space topology is ...

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Statistical Analysis of Stromboli Vlp Tremor in the Band [0.1–0.5]...

By: M. Palo; M. Falanga; S. De Martino; E. De Lauro

Description: Dipartimento di Fisica, Salerno University, via S. Allende, I-84081 Baronissi (SA), Italy. We analyze time series of Strombolian volcanic tremor, focusing our attention on the frequency band [0.1–0.5] Hz (very long period (VLP) tremor). Although this frequency band is largely affected by noise, we evidence two significant components by using Independent Component Analysis with the frequencies, respectively, of ~0.2 and ~0.4 Hz. We show that these compon...

Acernese, F., Ciaramella, A., De Martino, S., Falanga, M., and Tagliaferri, R.: Neural Networks for blind sources separation of Stomboli explosion quakes, IEEE Trans. Neural Netws., 14, 167–175, 2003.; Acernese, F., Ciaramella, A., De Martino, S., Falanga, M., Godano, C., and Tagliaferri, R.: Polarisation analysis of the independent components of low frequency events at Stromboli volcano (Eolian Island, Italy), J. Volc. Geotherm. Res., Special Issue: an introduction, edi...

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Stress States and Moment Rates of a Two-asperity Fault in the Pres...

By: E. Lorenzano; M. Dragoni

Description: Dipartimento di Fisica e Astronomia, Alma Mater Studiorum Università di Bologna, Viale Carlo Berti Pichat 8, 40127 Bologna, Italy. A fault containing two asperities with different strengths is considered. The fault is embedded in a shear zone subject to a constant strain rate by the motions of adjacent tectonic plates. The fault is modelled as a discrete dynamical system where the average values of stress, friction and slip on each asperity are considere...

Amendola, A. and Dragoni, M.: Dynamics of a two-fault system with viscoelastic coupling, Nonlin. Processes Geophys., 20, 1–10, doi:10.5194/npg-20-1-2013, 2013.; Bürgmann, R. and Dresen, G.: Rheology of the lower crust and upper mantle: evidence from rock mechanics, geodesy, and field observation, Ann. Rev. Earth Planet. Sci., 36, 531–567, 2008.; Carter, N. L.: Steady state flow of rocks, Rev. Geophys. Space Phys., 14, 3...

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Magnetic Reconnection Associated Fluctuations in the Deep Magnetot...

By: Z. Vörös

Description: Institute of Astro- and Particle Physics, University of Innsbruck, Austria. On the basis of ARTEMIS two-probe mission magnetic reconnection (MR) outflow associated magnetic fluctuations and turbulence are analyzed on 19 February 2011. In the deep-tail, at distances between X = 45 – 51 RE, evidence for reconnection associated plasma sheet thinning was found, accompanied by heating of the plasma sheet. Correlated flow and field r...

Alexandrova, O., Saur, J., Lacombe, C., Mangeney, A., Mitchell, J., Schwartz, S. J., and Robert, P.: Universality of solar wind turbulence spectrum from MHD to electron scales, Phys. Rev. Lett., 103, 165003, doi:10.1103/PhysRevLett.103.165003, 2009.; Angelopoulos, V., Mitchell, D. G., McEntire, R. W., Williams, D. J., Lui, A. T. Y., Krimigis, S. M., Decker, R. B., Christon, S. P., Kokubun, S., Yamamoto, T., Sai...

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External Forcing of Earthquake Swarms at Alpine Regions: Example f...

By: H. Küchenhoff; J. Wassermann; L. Fahrmeir; V. Svejdar

Description: Department of Statistics, Ludwig-Maximilians Univ. Munich, Germany. In the last few years, it has been shown that above-average rainfall and the following diffusion of excess water into subsurface structures is able to trigger earthquake swarms in the uppermost brittle portion of the Earth's crust. However, there is still an ongoing debate on whether the crust already needs to be in a critical-to-failure state or whether it is sufficient that water is ...

Agnew, D. C.: SPOTL: Some programs for ocean-tide loading, SIO Ref. Ser. 96-8, 35 pp., Scripps Institution of Oceanography, La Jolla, CA, 1996.; Ben-Zion Y. and Leary, P.: Thermoelastic strain in a half-space covered by unconsolidated material, BSSA, 76, 1447–1460, 1986.; Akaike, H.: Information theory and an extension of the maximum likelihood principle, in: 2nd International Symposium on Information Theory, edited by: Ptrov, B. N. and Csaki, F., Budapest, 276–81, 1973....

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Estimation of Soil Types by Non Linear Analysis of Remote Sensing ...

By: R. Gloaguen; C. Hahn

Description: Remote Sensing Group, Geology Institute, TU Bergakademie Freiberg, 09599 Freiberg, Germany. The knowledge of soil type and soil texture is crucial for environmental monitoring purpose and risk assessment. Unfortunately, their mapping using classical techniques is time consuming and costly. We present here a way to estimate soil types based on limited field observations and remote sensing data. Due to the fact that the relation between the soil types an...

Agresti, A.: An Introduction to Categorical Data Analysis, Wiley Press, p. 312, 1996; Bhattacharya, B. and Solomatine, D P.: Machine learning in soil classification, Neural Networks, 19, 186–195, 2006.; Bradley, J. V.: Distribution-Free Statistical Tests, Prentice-Hall Press, p. 388, 1968.; Burges, C. J C.: A Tutorial on Support Vector Machines for Pattern Recognition, Data Min. Knowl. Disk., 2, 121–167, 1998.; Chen, P.-H., Lin, C.-J., and Schölkopf, B.: A Tutorial on nu...

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Data Assimilation Experiments Using Diffusive Back-and-forth Nudgi...

By: E. Cosme; J. Verron; J. Blum; D. Auroux; G. A. Ruggiero; Y. Ourmières

Description: Université de Nice Sophia-Antipolis/LJAD, Nice, France. The diffusive back-and-forth nudging (DBFN) is an easy-to-implement iterative data assimilation method based on the well-known nudging method. It consists of a sequence of forward and backward model integrations, within a given time window, both of them using a feedback term to the observations. Therefore, in the DBFN, the nudging asymptotic behaviour is translated into an infinite number of iterati...

Anderson, J. L.: A local least squares framework for ensemble filtering, Mon. Weather Rev., 131, 634–642, 2003.; Abarbanel, H. D. I., Kostuk, M., and Whartenby, W.: Data assimilation with regularized nonlinear instabilities, Q. J. Roy. Meteorol. Soc., 136, 769–783, doi:10.1002/qj.600, doi:10.1002/qj.600, 2010.; Anthes, R. A.: Data Assimilation and Initialization of Hurricane Predict...

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