WorldWideScience

Sample records for dynamic critical phenomena

  1. New dynamic critical phenomena in nuclear and quark superfluids

    CERN Document Server

    Sogabe, Noriyuki

    2016-01-01

    We study the dynamic critical phenomena near the possible high-density QCD critical point inside the superfluid phase of nuclear and quark matter. We find that this critical point belongs to a new dynamic universality class beyond the conventional classification by Hohenberg and Halperin. We show that the speed of the superfluid phonon vanishes at the critical point and that the dynamic critical index is $z \\approx 2$.

  2. Dynamic critical phenomena from spectral functions on the lattice

    CERN Document Server

    Berges, J; Sexty, D

    2009-01-01

    We investigate spectral functions in the vicinity of the critical temperature of a second-order phase transition. Since critical phenomena in quantum field theories are governed by classical dynamics, universal properties can be computed using real-time lattice simulations. For the example of a relativistic single-component scalar field theory in 2+1 dimensions, we compute the spectral function described by universal scaling functions and extract the dynamic critical exponent z. Together with exactly known static properties of this theory, we obtain a verification from first principles that the relativistic theory is well described by the dynamic universality class of relaxational models with conserved density (Model C).

  3. Finite-size scaling study of dynamic critical phenomena in a vapor-liquid transition

    Science.gov (United States)

    Midya, Jiarul; Das, Subir K.

    2017-01-01

    Via a combination of molecular dynamics (MD) simulations and finite-size scaling (FSS) analysis, we study dynamic critical phenomena for the vapor-liquid transition in a three dimensional Lennard-Jones system. The phase behavior of the model has been obtained via the Monte Carlo simulations. The transport properties, viz., the bulk viscosity and the thermal conductivity, are calculated via the Green-Kubo relations, by taking inputs from the MD simulations in the microcanonical ensemble. The critical singularities of these quantities are estimated via the FSS method. The results thus obtained are in nice agreement with the predictions of the dynamic renormalization group and mode-coupling theories.

  4. Critical Phenomena in Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Gundlach Carsten

    1999-01-01

    Full Text Available As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term 'critical phenomena'. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. This review gives an introduction to the phenomena, tries to summarize the essential features of what is happening, and then presents extensions and applications of this basic scenario. Critical phenomena are of interest particularly for creating surprising structure from simple equations, and for the light they throw on cosmic censorship and the generic dynamics of general relativity.

  5. Critical Phenomena in Gravitational Collapse.

    Science.gov (United States)

    Gundlach, Carsten

    1999-01-01

    As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term "critical phenomena". They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. This review gives an introduction to the phenomena, tries to summarize the essential features of what is happening, and then presents extensions and applications of this basic scenario. Critical phenomena are of interest particularly for creating surprising structure from simple equations, and for the light they throw on cosmic censorship and the generic dynamics of general relativity.

  6. Critical Phenomena in Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Martín-García José M.

    2007-12-01

    Full Text Available As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term “critical phenomena”. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. Critical phenomena give a natural route from smooth initial data to arbitrarily large curvatures visible from infinity, and are therefore likely to be relevant for cosmic censorship, quantum gravity, astrophysics, and our general understanding of the dynamics of general relativity.

  7. Critical Phenomena in Finite Systems

    CERN Document Server

    Bonasera, A; Chiba, S

    2001-01-01

    We discuss the dynamics of finite systems within molecular dynamics models. Signatures of a critical behavior are analyzed and compared to experimental data both in nucleus-nucleus and metallic cluster collisions. We suggest the possibility to explore the instability region via tunneling. In this way we can obtain fragments at very low temperatures and densities. We call these fragments quantum drops.

  8. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril

    2001-01-01

    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in

  9. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril

    2000-01-01

    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. No longer an area of specialist interest, it has acquired a central focus in condensed matter studies. The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable information on important recent developments.The two review articles in this volume complement each other in a remarkable way. Both deal with what m

  10. Shell thickness and dynamic magnetic field effects on the critical phenomena of magnetic core-shell nanoparticles with spherical geometry

    Science.gov (United States)

    Yüksel, Yusuf

    2017-03-01

    By using Monte Carlo simulations for classical Heisenberg spins, we study the critical phenomena and ferrimagnetic properties of spherical nanoparticles with core-shell geometry. The particle core is composed of ferromagnetic spins, and it is coated by a ferromagnetic shell. Total size of the particle is fixed but the thickness of the shell is varied in such a way that the shell layer is grown at the expense of the core. Effects of the shell thickness, as well as dynamic magnetic field parameters such as oscillation period and field amplitude on the magnetization profiles, dynamic hysteresis loops and phase diagrams have been investigated for the present system. It has been found that as the shell thickness varies then the easy axis magnetization of the overall system may exhibit Q-, P-, L- and N- type behaviors based on the Neél terminology. We also found that three distinct anomalies originate in the thermal variation of specific heat with increasing field period. Dynamic hysteresis loops corresponding to off-axial magnetization components exhibit unconventional behavior such as double rings with symmetric shapes around the vertical axis over the h (t) = 0 line which may originate due to the stochastic resonance behavior of these components.

  11. Monte Carlos studies of critical and dynamic phenomena in mixed bond Ising model

    Science.gov (United States)

    Santos-Filho, J. B.; Moreno, N. O.; de Albuquerque, Douglas F.

    2010-11-01

    The phase transition of a random mixed-bond Ising ferromagnet on a cubic lattice model is studied both numerically and analytically. In this work, we use the Metropolis and Wolff algorithm with histogram technique and finite size scaling theory to simulate the dynamics of the system. We obtained the thermodynamic quantities such as magnetization, susceptibility, and specific heat. Our results were compared with those obtained using a new technique in effective field theory that employs similar probability distribution within the framework of two-site clusters.

  12. Critical phenomena in active matter

    Science.gov (United States)

    Paoluzzi, M.; Maggi, C.; Marini Bettolo Marconi, U.; Gnan, N.

    2016-11-01

    We investigate the effect of self-propulsion on a mean-field order-disorder transition. Starting from a φ4 scalar field theory subject to an exponentially correlated noise, we exploit the unified colored-noise approximation to map the nonequilibrium active dynamics onto an effective equilibrium one. This allows us to follow the evolution of the second-order critical point as a function of the noise parameters: the correlation time τ and the noise strength D . Our results suggest that the universality class of the model remains unchanged. We also estimate the effect of Gaussian fluctuations on the mean-field approximation finding an Ornstein-Zernike-like expression for the static structure factor at long wavelengths. Finally, to assess the validity of our predictions, we compare the mean-field theoretical results with numerical simulations of active Lennard-Jones particles in two and three dimensions, finding good qualitative agreement at small τ values.

  13. Black Hole Critical Phenomena Without Black Holes

    CERN Document Server

    Liebling, S L

    2000-01-01

    Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.

  14. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    Steven L Liebling

    2000-10-01

    Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.

  15. Critical phenomena in active matter

    Science.gov (United States)

    Paoluzzi, Matteo; Marchetti, M. Cristina; Claudio Maggi Collaboration; Umberto Marini Bettolo Marconi Collaboration; Nicoletta Gnan Collaboration

    A collection of active agents can organize in phases with structural properties remarkably similar to those of ordinary materials, such as active gases, liquids and glasses. These phases are formed, however, out of equilibrium, where the machinery of equilibrium statistical mechanics cannot be applied. It has recently been shown that models of particles with Gaussian colored noise can capture some of the nonequilibrium behavior of active Brownian particles, including motility-induced phase separation. By using the Unified Gaussian Colored Noise Approximation (UCNA) it has been possible to obtain an equilibrium-like probability distribution function and an effective free energy for active Brownian particles. Here we employ UCNA to examine the effect of colored noise on mean-field order-disorder transitions. Starting with a φ4 Landau model that undergoes a second-order phase transition as a function of a tuning parameter, we calculate the shift in transition due to colored noise as a function of the noise amplitude and correlation time τ. We find that the transition line exhibits reentrance as a function of τ. The mean-field theoretical predictions are compared with Molecular Dynamics simulations of active Lennard-Jones particles. We acknowledge support from NSF-DMR-1305184.

  16. Nonlinear Dynamic Phenomena in Mechanics

    CERN Document Server

    Warminski, Jerzy; Cartmell, Matthew P

    2012-01-01

    Nonlinear phenomena should play a crucial role in the design and control of engineering systems and structures as they can drastically change the prevailing dynamical responses. This book covers theoretical and applications-based problems of nonlinear dynamics concerned with both discrete and continuous systems of interest in civil and mechanical engineering. They include pendulum-like systems, slender footbridges, shape memory alloys, sagged elastic cables and non-smooth problems. Pendulums can be used as a dynamic absorber mounted in high buildings, bridges or chimneys. Geometrical nonlinear

  17. Parity-time symmetric quantum critical phenomena

    CERN Document Server

    Ashida, Yuto; Ueda, Masahito

    2016-01-01

    Symmetry plays a central role in the theory of phase transitions. Parity-time (PT) symmetry is an emergent notion in synthetic nonconservative systems, where the gain-loss balance creates a threshold for spontaneous symmetry breaking across which spectral singularity emerges. Considerable studies on PT symmetry have been conducted in optics and weakly interacting open quantum systems. Here by extending the idea of PT symmetry to strongly correlated many-body systems, we discover unconventional quantum critical phenomena, where spectral singularity and quantum criticality conspire to yield an exotic universality class which has no counterpart in known critical phenomena. Moreover, we find that superfluid correlation is anomalously enhanced owing to winding renormalization group flows in a PT-symmetry-broken quantum critical phase. Our findings can experimentally be tested in ultracold atoms.

  18. Critical Phenomena in Liquid-Liquid Mixtures

    Science.gov (United States)

    Jacobs, D. T.

    2000-04-01

    Critical phenomena provide intriguing and essential insight into many issues in condensed matter physics because of the many length scales involved. Large density or concentration fluctuations near a system's critical point effectively mask the identity of the system and produce universal phenomena that have been well studied in simple liquid-vapor and liquid-liquid systems. Such systems have provided useful model systems to test theoretical predictions which can then be extended to more complicated systems. Along various thermodynamic paths, several quantities exhibit a simple power-law dependence close to the critical point. The critical exponents describing these relationships are universal and should depend only on a universality class determined by the order-parameter and spatial dimensionality of the system. Liquid gas, binary fluid mixtures, uniaxial ferromagnetism, polymer-solvent, and protein solutions all belong to the same (Ising model) universality class. The diversity of critical systems that can be described by universal relations indicates that experimental measurements on one system should yield the same information as on another. Our experimental investigations have tested existing theory and also extended universal behavior into new areas. By measuring the coexistence curve, heat capacity, thermal expansion and static light scattering (turbidity) in various liquid-liquid and polymer-solvent systems, we have determined critical exponents and amplitudes that have sometimes confirmed and other times challenged current theory. Recent experiments investigating the heat capacity and light scattering in a liquid-liquid mixture very close to the critical point will be discussed. This research is currently supported by The Petroleum Research Fund and by NASA grant NAG8-1433 with some student support from NSF-DMR 9619406.

  19. Phantom black holes and critical phenomena

    CERN Document Server

    Azreg-Aïnou, Mustapha; Rodrigues, Manuel E

    2014-01-01

    We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-Dilaton theory. Leaving aside the normal Reissner-Nordstr\\"om black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to ...

  20. Surfactant-based critical phenomena in microgravity

    Science.gov (United States)

    Kaler, Eric W.; Paulaitis, Michael E.

    1994-01-01

    The objective of this research project is to characterize by experiment and theoretically both the kinetics of phase separation and the metastable structures produced during phase separation in a microgravity environment. The particular systems we are currently studying are mixtures of water, nonionic surfactants, and compressible supercritical fluids at temperatures and pressures where the coexisting liquid phases have equal densities (isopycnic phases). In this report, we describe experiments to locate equilibrium isopycnic phases and to determine the 'local' phase behavior and critical phenomena at nearby conditions of temperature, pressure, and composition. In addition, we report the results of preliminary small angle neutron scattering (SANS) experiments to characterize microstructures that exist in these mixtures at different fluid densities.

  1. Quantum field theory and critical phenomena

    CERN Document Server

    Zinn-Justin, Jean

    1996-01-01

    Over the last twenty years quantum field theory has become not only the framework for the discussion of all fundamental interactions except gravity, but also for the understanding of second-order phase transitions in statistical mechanics. This advanced text is based on graduate courses and summer schools given by the author over a number of years. It approaches the subject in terms of path and functional intergrals, adopting a Euclidean metric and using the language of partition and correlation functions. Renormalization and the renormalization group are examined, as are critical phenomena and the role of instantons. Changes for this edition 1. Extensive revision to eliminate a few bugs that had survived the second edition and (mainly) to improve the pedagogical presentation, as a result of experience gathered by lecturing. 2. Additional new topics; holomorphic or coherent state path integral; functional integral and representation of the field theory S-matrix in the holomorphic formalis; non-relativistic li...

  2. Critical phenomena in ferromagnetic antidot lattices

    Directory of Open Access Journals (Sweden)

    R. Zivieri

    2016-05-01

    Full Text Available In this paper a quantitative theoretical formulation of the critical behavior of soft mode frequencies as a function of an applied magnetic field in two-dimensional Permalloy square antidot lattices in the nanometric range is given according to micromagnetic simulations and simple analytical calculations. The degree of softening of the two lowest-frequency modes, namely the edge mode and the fundamental mode, corresponding to the field interval around the critical magnetic field, can be expressed via numerical exponents. For the antidot lattices studied we have found that: a the ratio between the critical magnetic field and the in-plane geometric aspect ratio and (b the ratio between the numerical exponents of the frequency power laws of the fundamental mode and of the edge mode do not depend on the geometry. The above definitions could be extended to other types of in-plane magnetized periodic magnetic systems exhibiting soft-mode dynamics and a fourfold anisotropy.

  3. Macroscopic Quantum Phenomena from the Correlation, Coupling and Criticality Perspectives

    Science.gov (United States)

    Chou, C. H.; Hu, B. L.; Subaşi, Y.

    2011-12-01

    In this sequel paper we explore how macroscopic quantum phenomena can be measured or understood from the behavior of quantum correlations which exist in a quantum system of many particles or components and how the interaction strengths change with energy or scale, under ordinary situations and when the system is near its critical point. We use the nPI (master) effective action related to the Boltzmann-BBGKY / Schwinger-Dyson hierarchy of equations as a tool for systemizing the contributions of higher order correlation functions to the dynamics of lower order correlation functions. Together with the large N expansion discussed in our first paper [1] we explore 1) the conditions whereby an H-theorem is obtained, which can be viewed as a signifier of the emergence of macroscopic behavior in the system. We give two more examples from past work: 2) the nonequilibrium dynamics of N atoms in an optical lattice under the large Script N (field components), 2PI and second order perturbative expansions, illustrating how N and Script N enter in these three aspects of quantum correlations, coherence and coupling strength. 3) the behavior of an interacting quantum system near its critical point, the effects of quantum and thermal fluctuations and the conditions under which the system manifests infrared dimensional reduction. We also discuss how the effective field theory concept bears on macroscopic quantum phenomena: the running of the coupling parameters with energy or scale imparts a dynamical-dependent and an interaction-sensitive definition of 'macroscopia'.

  4. Active Cyber Defense Dynamics Exhibiting Rich Phenomena

    CERN Document Server

    Zheng, Ren; Xu, Shouhuai

    2016-01-01

    The Internet is a man-made complex system under constant attacks (e.g., Advanced Persistent Threats and malwares). It is therefore important to understand the phenomena that can be induced by the interaction between cyber attacks and cyber defenses. In this paper, we explore the rich phenomena that can be exhibited when the defender employs active defense to combat cyber attacks. To the best of our knowledge, this is the first study that shows that {\\em active cyber defense dynamics} (or more generally, {\\em cybersecurity dynamics}) can exhibit the bifurcation and chaos phenomena. This has profound implications for cyber security measurement and prediction: (i) it is infeasible (or even impossible) to accurately measure and predict cyber security under certain circumstances; (ii) the defender must manipulate the dynamics to avoid such {\\em unmanageable situations} in real-life defense operations.

  5. Probabilistic Dynamic Logic of Phenomena and Cognition

    CERN Document Server

    Vityaev, Evgenii; Perlovsky, Leonid; Smerdov, Stanislav

    2011-01-01

    The purpose of this paper is to develop further the main concepts of Phenomena Dynamic Logic (P-DL) and Cognitive Dynamic Logic (C-DL), presented in the previous paper. The specific character of these logics is in matching vagueness or fuzziness of similarity measures to the uncertainty of models. These logics are based on the following fundamental notions: generality relation, uncertainty relation, simplicity relation, similarity maximization problem with empirical content and enhancement (learning) operator. We develop these notions in terms of logic and probability and developed a Probabilistic Dynamic Logic of Phenomena and Cognition (P-DL-PC) that relates to the scope of probabilistic models of brain. In our research the effectiveness of suggested formalization is demonstrated by approximation of the expert model of breast cancer diagnostic decisions. The P-DL-PC logic was previously successfully applied to solving many practical tasks and also for modelling of some cognitive processes.

  6. Developing Critical Thinking through the Study of Paranormal Phenomena.

    Science.gov (United States)

    Wesp, Richard; Montgomery, Kathleen

    1998-01-01

    Argues that accounts of paranormal phenomena can serve as an ideal medium in which to encourage students to develop critical-thinking skills. Describes a cooperative-learning approach used to teach critical thinking in a course on paranormal events. Reports that critical-thinking skills increased and that the course received favorable student…

  7. Critical Phenomena of Rainfall in Ecuador

    Science.gov (United States)

    Serrano, Sh.; Vasquez, N.; Jacome, P.; Basile, L.

    2014-02-01

    Self-organized criticality (SOC) is characterized by a power law behavior over complex systems like earthquakes and avalanches. We study rainfall using data of one day, 3 hours and 10 min temporal resolution from INAMHI (Instituto Nacional de Meteorologia e Hidrologia) station at Izobamba, DMQ (Metropolitan District of Quito), satellite data over Ecuador from Tropical Rainfall Measure Mission (TRMM,) and REMMAQ (Red Metropolitana de Monitoreo Atmosferico de Quito) meteorological stations over, respectively. Our results show a power law behavior of the number of rain events versus mm of rainfall measured for the high resolution case (10 min), and as the resolution decreases this behavior gets lost. This statistical property is the fingerprint of a self-organized critical process (Peter and Christensen, 2002) and may serve as a benchmark for models of precipitation based in phase transitions between water vapor and precipitation (Peter and Neeling, 2006).

  8. Macroscopic Quantum Phenomena from the Correlation, Coupling and Criticality Perspectives

    CERN Document Server

    Chou, C H; Subasi, Y

    2011-01-01

    In this sequel paper we explore how macroscopic quantum phenomena can be measured or understood from the behavior of quantum correlations which exist in a quantum system of many particles or components and how the interaction strengths change with energy or scale, under ordinary situations and when the system is near its critical point. We use the nPI (master) effective action related to the Boltzmann-BBGKY / Schwinger-Dyson hierarchy of equations as a tool for systemizing the contributions of higher order correlation functions to the dynamics of lower order correlation functions. Together with the large N expansion discussed in our first paper(MQP1) we explore 1) the conditions whereby an H-theorem is obtained, which can be viewed as a signifier of the emergence of macroscopic behavior in the system. We give two more examples from past work: 2) the nonequilibrium dynamics of N atoms in an optical lattice under the large $\\cal N$ (field components), 2PI and second order perturbative expansions, illustrating h...

  9. Semiology of subtle motor phenomena in critically ill patients.

    Science.gov (United States)

    Florea, Bogdan; Beniczky, Simona Alexandra; Demény, Helga; Beniczky, Sándor

    2017-05-01

    to investigate the semiology of subtle motor phenomena in critically ill patients, with- versus without nonconvulsive status epilepticus (NCSE). 60 consecutive comatose patients, in whom subtle motor phenomena were observed in the intensive care unit (ICU), were analysed prospectively. The semiology of the subtle phenomena was described from video-recordings, blinded to all other data. For each patient, the type, location and occurrence-pattern/duration were described. EEGs recorded in the ICU were classified using the Salzburg criteria for NCSE. only 23% (14/60) of the patients had NCSE confirmed by EEG. None of the semiological features could distinguish between patients with NCSE and those without. In both groups, the following phenomena were most common: discrete myoclonic muscle twitching and discrete tonic muscle activation. Besides these, automatisms and eye deviation were observed in both groups. subtle motor phenomena in critically ill patients can raise the suspicion of NCSE. Nevertheless, EEG is needed to confirm the diagnosis, since none of the semiological features are specific. Copyright © 2017 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

  10. Molecular dynamics simulation of laser shock phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Ichirou [Japan Atomic Energy Research Inst., Kansai Research Establishment, Advanced Photon Research Center, Neyagawa, Osaka (Japan).

    2001-10-01

    Recently, ultrashort-pulse lasers with high peak power have been developed, and their application to materials processing is expected as a tool of precision microfabrication. When a high power laser irradiates, a shock wave propagates into the material and dislocations are generated. In this paper, laser shock phenomena of the metal were analyzed using the modified molecular dynamics method, which has been developed by Ohmura and Fukumoto. The main results obtained are summarized as follows: (1) The shock wave induced by the Gaussian beam irradiation propagates radially from the surface to the interior. (2) A lot of dislocations are generated at the solid-liquid interface by the propagation of a shock wave. (3) Some dislocations are moved instantaneously with the velocity of the longitudinal wave when the shock wave passes, and their velocity is not larger than the transverse velocity after the shock wave has passed. (author)

  11. Critical phenomena in the aspherical gravitational collapse of radiation fluids

    CERN Document Server

    Baumgarte, Thomas W

    2015-01-01

    We study critical phenomena in the gravitational collapse of a radiation fluid. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We identify the critical solution in spherically symmetric collapse, find evidence for its universality, and study the approach to this critical solution in the absence of spherical symmetry. For the cases that we consider, aspherical deviations from the spherically symmetric critical solution decay in damped oscillations in a manner that is consistent with the behavior found by Mart\\'in-Garc\\'ia and Gundlach in perturbative calculations. Our simulations are performed with an unconstrained evolution code, implemented in spherical polar coordinates, and adopting "moving-puncture" coordinates.

  12. Critical phenomena: 150 years since Cagniard de la Tour

    CERN Document Server

    Berche, Bertrand; Kenna, Ralph

    2009-01-01

    Critical phenomena were discovered by Cagniard de la Tour in 1822, who died 150 years ago. In order to mark this anniversary, the context and the early history of his discovery is reviewed. We then follow with a brief sketch of the history of critical phenomena, indicating the main lines of development until the present date. Os fen\\'omenos cr\\'{\\i}ticos foram descobertos pelo Cagniard de la Tour em Paris em 1822. Para comemorar os 150 anos da sua morte, o contexto e a hist\\'oria initial da sua descoberta \\'e contada. Conseguimos com uma descri\\c{c}\\~ao breve da hist\\'oria dos fen\\'emenos cr\\'{\\i}ticos, indicando as linhas principais do desenvolvimento at\\'e o presente.

  13. Critical phenomena in one dimension from a Bethe ansatz perspective

    Science.gov (United States)

    Guan, Xiwen

    2014-08-01

    This article briefly reviews recent theoretical developments in quantum critical phenomena in one-dimensional (1D) integrable quantum gases of cold atoms. We present a discussion on quantum phase transitions, universal thermodynamics, scaling functions and correlations for a few prototypical exactly solved models, such as the Lieb-Liniger Bose gas, the spin-1 Bose gas with antiferromagnetic spin-spin interaction, the two-component interacting Fermi gas as well as spin-3/2 Fermi gases. We demonstrate that their corresponding Bethe ansatz solutions provide a precise way to understand quantum many-body physics, such as quantum criticality, Luttinger liquids (LLs), the Wilson ratio, Tan's Contact, etc. These theoretical developments give rise to a physical perspective using integrability for uncovering experimentally testable phenomena in systems of interacting bosonic and fermonic ultracold atoms confined to 1D.

  14. High-speed imaging of dynamic shock wave reflection phenomena

    CSIR Research Space (South Africa)

    Naidoo, K

    2010-09-01

    Full Text Available Dynamic shock wave reflection generated by a rapidly pitching wedge in a steady supersonic free stream has been studied with numerical simulation previously. An experimental facility was developed for the investigation of these dynamic phenomena...

  15. Hyperchaotic phenomena in dynamic decision making

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Mosekilde, Erik; Sterman, John David

    1992-01-01

    of this article is to show how the decision making behavior of real people in simulated corporate environments can lead to chaotic, hyperchaotic and higher-order hyperchaotic phenomena. Characteristics features of these complicated forms of behavior are analyzed with particular emphasis on an interesting form...

  16. Critical phenomena of emergent magnetic monopoles in a chiral magnet.

    Science.gov (United States)

    Kanazawa, N; Nii, Y; Zhang, X-X; Mishchenko, A S; De Filippis, G; Kagawa, F; Iwasa, Y; Nagaosa, N; Tokura, Y

    2016-05-16

    Second-order continuous phase transitions are characterized by symmetry breaking with order parameters. Topological orders of electrons, characterized by the topological index defined in momentum space, provide a distinct perspective for phase transitions, which are categorized as quantum phase transitions not being accompanied by symmetry breaking. However, there are still limited observations of counterparts in real space. Here we show a real-space topological phase transition in a chiral magnet MnGe, hosting a periodic array of hedgehog and antihedgehog topological spin singularities. This transition is driven by the pair annihilation of the hedgehogs and antihedgehogs acting as monopoles and antimonopoles of the emergent electromagnetic field. Observed anomalies in the magnetoresistivity and phonon softening are consistent with the theoretical prediction of critical phenomena associated with enhanced fluctuations of emergent field near the transition. This finding reveals a vital role of topology of the spins in strongly correlated systems.

  17. Nonlinear dynamic phenomena in the beer model

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Laugesen, Jakob Lund

    2007-01-01

    The production-distribution system or "beer game" is one of the most well-known system dynamics models. Notorious for the complex dynamics it produces, the beer game has been used for nearly five decades to illustrate how structure generates behavior and to explore human decision making. Here we...

  18. Collapsing shells, critical phenomena and black hole formation

    CERN Document Server

    Cardoso, Vitor

    2016-01-01

    We study the gravitational collapse of two thin shells of matter, in asymptotically flat spacetime or constrained to move within a spherical box. We show that this simple two-body system has surprisingly rich dynamics, which includes prompt collapse to a black hole, perpetually oscillating solutions or black hole formation at arbitrarily large times. Collapse is induced by shell crossing and the black hole mass depends sensitively on the number of shell crossings. At certain critical points, the black hole mass exhibits critical behavior, determined by the change in parity (even or odd) of the number of crossings, with or without mass-gap during the transition. Some of the features we observe are reminiscent of confined scalars undergoing "turbulent" dynamics.

  19. Percolation and Critical Phenomena of AN Attractive Micellar System

    Science.gov (United States)

    Mallamace, F.; Chen, S. H.; Gambadauro, P.; Lombardo, D.; Faraone, A.; Tartaglia, P.

    In this work we study an attractive micellar system for which the percolation curve terminates near the critical point. We have studied such an intriguing situation by means of scattering (elastic and dynamical) and viscoelasticity experiments. Obtained data are accounted by considering in a proper way the fractal clustering processes typical of percolating systems and the related scaling concepts. We observe that the main role in the system structure and dynamics it is played by the cluster's partial screening of hydrodynamic interaction. This behaves on approaching the percolation threshold dramatic effects on the system rheological properties and on the density decay relaxations. The measured correlation functions assume a stretched exponential form and the system becomes strongly viscoelastic. The overall behavior of the measured dynamical and structural parameters indicates, that in the present micellar system, the clustering process originates dilute, poly-disperse and swelling structures. Finally, this originates an interesting situation observed in the present experiment. As it has been previously, proposed by A. Coniglio et al., percolation clusters can be considered to be "Ising clusters" with the same properties as the Fisher's critical droplets. Therefore at the critical point the percolation connectedness length (ξp) can be assumed as the diverging correlation length (ξp ≡ ξ) and the mean cluster size diverges as the susceptibility.

  20. Random matrix theory and critical phenomena in quantum spin chains.

    Science.gov (United States)

    Hutchinson, J; Keating, J P; Mezzadri, F

    2015-09-01

    We compute critical properties of a general class of quantum spin chains which are quadratic in the Fermi operators and can be solved exactly under certain symmetry constraints related to the classical compact groups U(N),O(N), and Sp(2N). In particular we calculate critical exponents s,ν, and z, corresponding to the energy gap, correlation length, and dynamic exponent, respectively. We also compute the ground state correlators 〈σ_{i}^{x}σ_{i+n}^{x}〉_{g},〈σ_{i}^{y}σ_{i+n}^{y}〉_{g}, and 〈∏_{i=1}^{n}σ_{i}^{z}〉_{g}, all of which display quasi-long-range order with a critical exponent dependent upon system parameters. Our approach establishes universality of the exponents for the class of systems in question.

  1. Nonlinear dynamics and chaotic phenomena an introduction

    CERN Document Server

    Shivamoggi, Bhimsen K

    2014-01-01

    This book starts with a discussion of nonlinear ordinary differential equations, bifurcation theory and Hamiltonian dynamics. It then embarks on a systematic discussion of the traditional topics of modern nonlinear dynamics  -- integrable systems, Poincaré maps, chaos, fractals and strange attractors. The Baker’s transformation, the logistic map and Lorenz system are discussed in detail in view of their central place in the subject. There is a detailed discussion of solitons centered around the Korteweg-deVries equation in view of its central place in integrable systems. Then, there is a discussion of the Painlevé property of nonlinear differential equations which seems to provide a test of integrability. Finally, there is a detailed discussion of the application of fractals and multi-fractals to fully-developed turbulence -- a problem whose understanding has been considerably enriched by the application of the concepts and methods of modern nonlinear dynamics. On the application side, there is a special...

  2. Critical phenomena in the spreading of opinion consensus and disagreement

    Directory of Open Access Journals (Sweden)

    Andrés Chacoma

    2014-08-01

    Full Text Available We consider a class of models of opinion formation where the dissemination of individual opinions occurs through the spreading of local consensus and disagreement. We study the emergence of full collective consensus or maximal disagreement in one- and two-dimensional arrays. In both cases, the probability of reaching full consensus exhibits well-defined scaling properties as a function of the system size. Two-dimensional systems, in particular, possess nontrivial exponents and critical points. The dynamical rules of our models, which emphasize the interaction between small groups of agents, should be considered as complementary to the imitation mechanisms of traditional opinion dynamics. Received: 11 March 2014, Accepted: 1 August 2014; Reviewed by: F. Bagnoli, Dipartimento di Fisica ed Astronomia, Universita degli Studi di Firenze, Italy; Edited by: G. Martinez Mekler; DOI: http://dx.doi.org/10.4279/PIP.060003 Cite as: A Chacoma, D H Zanette, Papers in Physics 6, 060003 (2014

  3. Emergence of dynamical order synchronization phenomena in complex systems

    CERN Document Server

    Manrubia, Susanna C; Zanette, Damián H

    2004-01-01

    Synchronization processes bring about dynamical order and lead tospontaneous development of structural organization in complex systemsof various origins, from chemical oscillators and biological cells tohuman societies and the brain. This book provides a review and adetailed theoretical analysis of synchronization phenomena in complexsystems with different architectures, composed of elements withperiodic or chaotic individual dynamics. Special attention is paid tostatistical concepts, such as nonequilibrium phase transitions, orderparameters and dynamical glasses.

  4. Universality classes and critical phenomena in confined liquid systems

    Directory of Open Access Journals (Sweden)

    A.V. Chalyi

    2013-06-01

    Full Text Available It is well known that the similar universal behavior of infinite-size (bulk systems of different nature requires the same basic conditions: space dimensionality; number components of order parameter; the type (short- or long-range of the intermolecular interaction; symmetry of the fluctuation part of thermodynamical potential. Basic conditions of similar universal behavior of confined systems needs the same supplementary conditions such as the number of monolayers for a system confinement; low crossover dimensionality, i.e., geometric form of restricted volume; boundary conditions on limiting surfaces; physical properties under consideration. This review paper is aimed at studying all these conditions of similar universal behavior for diffusion processes in confined liquid systems. Special attention was paid to the effects of spatial dispersion and low crossover dimensionality. This allowed us to receive receiving correct nonzero expressions for the diffusion coefficient at the critical point and to take into account the specific geometric form of the confined liquid volume. The problem of 3D⇔2D dimensional crossover was analyzed. To receive a smooth crossover for critical exponents, the Kawasaki-like approach from the theory of mode coupling in critical dynamics was proposed. This ensured a good agreement between data of computer experiment and theoretical calculations of the size dependence of the critical temperature Tc(H of water in slitlike pores. The width of the quasi-elastic scattering peak of slow neutrons near the structural phase transition in the aquatic suspensions of plasmatic membranes (mesostructures with the typical thickness up to 10 nm was studied. It was shown that the width of quasi-elastic peak of neutron scattering decreases due to the process of cell proliferation, i.e., with an increase of the membrane size (including the membrane thickness. Thus, neutron studies could serve as an additional diagnostic test for the

  5. Computational and experimental investigation of dynamic shock reflection phenomena

    CSIR Research Space (South Africa)

    Naidoo, K

    2007-07-01

    Full Text Available This paper reports the development of an experimental facility for the investigation of dynamic, two-dimensional shock reflection phenomena generated by a rapidly pitching wedge in proximity of an ideal wall. CFD simulations of the rapidly pitching...

  6. Synchronization Phenomena in an Array of Population Dynamic Systems

    DEFF Research Database (Denmark)

    Postnov, D.E.; Balanov, A.G.; Mosekilde, Erik

    1998-01-01

    The paper applies continuation methods to examine synchronization phenomena that can arise in a cascaded system of population dynamic models. The individual model describes a bacterial population interacting with a population of viruses that attack the cells. Coupling between the subsystems...

  7. Thermal dynamics of thermoelectric phenomena from frequency resolved methods

    OpenAIRE

    2016-01-01

    Understanding the dynamics of thermoelectric (TE) phenomena is important for the detailed knowledge of the operation of TE materials and devices. By analyzing the impedance response of both a single TE element and a TE device under suspended conditions, we provide new insights into the thermal dynamics of these systems. The analysis is performed employing parameters such as the thermal penetration depth, the characteristic thermal diffusion frequency and the thermal diffusion time. It is show...

  8. Critical dynamics near QCD critical point

    CERN Document Server

    Minami, Yuki

    2012-01-01

    In this thesis, we study the critical dynamics near the QCD critical point. Near the critical point, the relevant modes for the critical dynamics are identified as the hydrodynamic modes. Thus, we first study the linear dynamics of them by the relativistic hydrodynamics. We show that the thermal diffusion mode is the most relevant mode, whereas the sound mode is suppressed around the critical point. We also find that the Landau equation, which is believed to be an acausal hydrodynamic equation, has no problem to describe slowly varying fluctuations. Moreover, we find that the Israel-Stewart equation, which is a causal one, gives the same result as the Landau equation gives in the long-wavelength region. Next, we study the nonlinear dynamics of the hydrodynamic modes by the nonlinear Langevin equation and the dynamic renormalization group (RG). In the vicinity of the critical point, the usual hydrodynamics breaks down by large fluctuations. Thus, we must consider the nonlinear Langevin equation. We construct t...

  9. Ship-induced solitons as a manifestation of critical phenomena

    CERN Document Server

    Zakharov, Stanyslav

    2008-01-01

    A ship, moving with small acceleration in a reservoir of uniform depth, can be subjected to a sudden hydrodynamical impact similar to collision with an underwater rock, and on water surface unusual solitary wave will start running. The factors responsible for formation of solitons induced by a moving ship are analyzed. Emphasis is given to a phenomenon observed by John Scott Russell more 170 years ago when a sudden stop of a boat preceded the occurrence of exotic water dome. In dramatic changes of polemic about the stability and mathematical description of a solitary wave, the question why "Russell's wave" occurred has not been raised, though attempts its recreation invariably suffered failure. In our report the conditions disclosing the principle of the famous event as a critical phenomenon are described. In a reservoir of uniform depth a ship can confront by a dynamic barrier within narrow limits of ship's speed and acceleration. In a wider interval of parameters a ship generates a satellite wave, which can...

  10. Role and Nature of Intermittency and Self-Organized Criticality in Solar Phenomena

    Science.gov (United States)

    Abramenko, V.

    2007-12-01

    In Solar Physics, last decades demonstrated a considerable progress in understanding of both macro-scale processes (e.g., magneto-hydro-dynamic modeling of the heliosphere, magnetic field modeling in coronal structures, etc.), on the one hand, and micro-scale phenomena (e.g., turbulence of the solar plasma), on the other hand. Further progress seems to be associated with our realization of how various micro-scale processes are involved and manifested in the macro-scale behavior of the entire Sun. A similar problem unavoidably arises in studies of any other non-linear dynamical dissipative system in Nature. Such systems that can be placed in between a chaos and a completely determined structure. The goal of this talk is to show how the conceptions of intermittency, multifractality, percolation, and self-organized criticality are closely intertwined, and how they are currently elaborated in Solar Physics and help in understanding of unpredictable behavior of our closest star.

  11. A Black-Hole Primer: Particles, Waves, Critical Phenomena and Superradiant Instabilities

    CERN Document Server

    Berti, Emanuele

    2014-01-01

    These notes were prepared for a lecture on black holes delivered at the DPG Physics School "General Relativity @ 99" (Physikzentrum Bad Honnef, Germany, September 2014). The common thread of the lecture is the relation between geodesic stability and black-hole perturbations in the geometric optics limit. Chapter 1 establishes notation and discusses a common misconception on Michell's "Newtonian black holes". Chapters 2 and 3 deal with particle dynamics and wave dynamics in black-hole spacetimes, respectively. All calculations should be simple enough that they can be done with pen and paper. Chapter 4 builds on this introduction to discuss two exciting topics in current research: critical phenomena in black-hole mergers and the black-hole bomb instability.

  12. Dynamical system analysis of unstable flow phenomena in centrifugal blower

    Directory of Open Access Journals (Sweden)

    Garcia David

    2015-09-01

    Full Text Available Methods of dynamical system analysis were employed to analyze unsteady phenomena in a centrifugal blower. Pressure signals gathered at different control points were decomposed into their Principal Components (PCs by means of Singular Spectrum Analysis (SSA. Certain number of PCs was considered in the analysis based on their statistical correlation. Projection of the original signal onto its PCs allowed to draw the phase trajectory that clearly separated non-stable blower working conditions from its regular operation.

  13. Random matrix theory and critical phenomena in quantum spin chains

    Science.gov (United States)

    Hutchinson, J.; Keating, J. P.; Mezzadri, F.

    2015-09-01

    We compute critical properties of a general class of quantum spin chains which are quadratic in the Fermi operators and can be solved exactly under certain symmetry constraints related to the classical compact groups $U(N)$, $O(N)$ and $Sp(2N)$. In particular we calculate critical exponents $s$, $\

  14. On the critical phenomena and thermodynamics of charged topological dilaton AdS black holes

    CERN Document Server

    Zhao, Ren; Ma, Meng-Sen; Zhang, Li-Chun

    2013-01-01

    In this paper, we study the phase structure and equilibrium state space geometry of charged topological dilaton black holes in $(n+1)$-dimensional anti-de Sitter spacetime. By considering the pairs of parameters $(P\\sim V)$ and $(Q\\sim U)$ as variables, we analyze the phase structure and critical phenomena of black holes and discuss the relation between the two kinds of critical phenomena. We find that the phase structures and critical phenomena drastically depend on the cosmological constant $l$ (or the static electric charge $Q$ of the black holes), dimensionality $n$ and dilaton field $\\Phi $.

  15. SANS studies of critical phenomena in ternary mixtures

    CERN Document Server

    Bulavyn, L A; Hohryakov, A; Garamus, V; Avdeev, M; Almasy, L

    2002-01-01

    Critical behaviour of a quasi-binary liquid mixture is investigated by small-angle neutron scattering. Analysis of the changes of the critical parameters, caused by addition of a small amount of electrolyte into the binary mixture 3-methylpyridine-heavy water, shows that the third component does not change the 3D Ising-type behaviour of the system; a crossover towards the mean-field behaviour is not observed. (orig.)

  16. Quantitative physical models of volcanic phenomena for hazards assessment of critical infrastructures

    Science.gov (United States)

    Costa, Antonio

    2016-04-01

    Volcanic hazards may have destructive effects on economy, transport, and natural environments at both local and regional scale. Hazardous phenomena include pyroclastic density currents, tephra fall, gas emissions, lava flows, debris flows and avalanches, and lahars. Volcanic hazards assessment is based on available information to characterize potential volcanic sources in the region of interest and to determine whether specific volcanic phenomena might reach a given site. Volcanic hazards assessment is focussed on estimating the distances that volcanic phenomena could travel from potential sources and their intensity at the considered site. Epistemic and aleatory uncertainties strongly affect the resulting hazards assessment. Within the context of critical infrastructures, volcanic eruptions are rare natural events that can create severe hazards. In addition to being rare events, evidence of many past volcanic eruptions is poorly preserved in the geologic record. The models used for describing the impact of volcanic phenomena generally represent a range of model complexities, from simplified physics based conceptual models to highly coupled thermo fluid dynamical approaches. Modelling approaches represent a hierarchy of complexity, which reflects increasing requirements for well characterized data in order to produce a broader range of output information. In selecting models for the hazard analysis related to a specific phenomenon, questions that need to be answered by the models must be carefully considered. Independently of the model, the final hazards assessment strongly depends on input derived from detailed volcanological investigations, such as mapping and stratigraphic correlations. For each phenomenon, an overview of currently available approaches for the evaluation of future hazards will be presented with the aim to provide a foundation for future work in developing an international consensus on volcanic hazards assessment methods.

  17. Critical Phenomena of the Disorder Driven Localization-Delocalization Transition

    CERN Document Server

    Marc-Ruehlaende

    2001-01-01

    Metal-to-insulator transitions are generally linked to two phenomena: electron-electron correlations and disorder. Although real systems are usually responding to a mixture of both, they can be classified as undergoing a Mott-transition, if the former process dominates, or an Anderson-transition, if the latter dominates. High-T sub c superconductors, e.g., are a candidate for the first class. Materials in which disorder drives the metal-to-insulator transition include doped semiconductors and amorphous materials. After briefly reviewing the previous research on transport in disordered materials and the disorder-induced metal-to-insulator transition, a summary of the model and the methods used in subsequent chapters is given.

  18. Critical Phenomena of the Disorder Driven Localization-Delocalization Transition

    Energy Technology Data Exchange (ETDEWEB)

    Ruhlander, Marc [Iowa State Univ., Ames, IA (United States)

    2002-12-31

    Metal-to-insulator transitions are generally linked to two phenomena: electron-electron correlations and disorder. Although real systems are usually responding to a mixture of both, they can be classified as undergoing a Mott-transition, if the former process dominates, or an Anderson-transition, if the latter dominates. High-Tc superconductors, e.g., are a candidate for the first class. Materials in which disorder drives the metal-to-insulator transition include doped semiconductors and amorphous materials. After briefly reviewing the previous research on transport in disordered materials and the disorder-induced metal-to-insulator transition, a summary of the model and the methods used in subsequent chapters is given.

  19. Behavior of the Widom line in critical phenomena.

    Science.gov (United States)

    Luo, Jiayuan; Xu, Limei; Lascaris, Erik; Stanley, H Eugene; Buldyrev, Sergey V

    2014-04-04

    Using linear scaling theory, we study the behavior of response functions extrema in the vicinity of the critical point. We investigate how the speed of convergence of the loci of response function extrema to the Widom line depends on the parameters of the linear scaling theory. We find that when the slope of the coexistence line is near zero, the line of specific heat maxima does not follow the Widom line but instead follows the coexistence line. This has relevance for the detection of liquid-liquid critical points, which can exhibit a near-horizontal coexistence line. Our theoretical predictions are confirmed by computer simulations of a family of spherically symmetric potentials.

  20. Critical Transport Phenomena in Fluid Helium Under Low Gravity

    Science.gov (United States)

    Meyer, H.; Behringer, R. P.

    1985-01-01

    The feasibility of carrying out measurements of certain critical transport properties of pure fluid under conditions of low gravity was studied. These properties are the thermal conductivity, kappa, the shear viscosity zeta and the diffusive relaxation time tau, which are predicted to diverge (tend to infinity) as the liquid-vapor critical point is approached. However, in this critical region, the Earth's gravity effect becomes very important. As the critical point is approached, the gravity effects increasingly distort the results. The reason for this is that the compressibility of the fluid also diverges and under the influence of gravity causes a vertical density gradient in the fluid, which is significant even when very thin fluid layers (typically 1 mm high) are being used. The result is that the temperature dependence of kappa, zeta, and tau tends to flatten off as T sub c is approached instead of continuing to increase, and therefore the predictions from the renormalization group and mode coupling theories cannot be subjected to a satisfactory test.

  1. Bifurcation phenomena in internal dynamics of gear systems

    Directory of Open Access Journals (Sweden)

    Hortel M.

    2007-10-01

    Full Text Available The impact effects in gear mesh represent specific phenomena in the dynamic investigation of highspeed light transmission systems with kinematic couplings. They are caused of greater dynamic than static elastic deformations in meshing gear profiles. In term of internal dynamics they are influenced among others by time heteronomous stiffness functions in gear mesh and resonance tuning of stiffness level. The damping in gear mesh and in gear system is concerned significantly in the amplitude progress, greatness and phase shift of relative motion towards stiffness function alternatively towards its modify form in gear mesh. In consequence of these and another actions rise above resonance characteristics certain singular locations with jump amplitude course.

  2. Near-Critical Phenomena in Intracellular Metabolite Pools

    Science.gov (United States)

    Elf, Johan; Paulsson, Johan; Berg, Otto G.; Ehrenberg, Måns

    2003-01-01

    The supply and consumption of metabolites in living cells are catalyzed by enzymes. Here we consider two of the simplest schemes where one substrate is eliminated through Michaelis-Menten kinetics, and where two types of substrates are joined together by an enzyme. It is demonstrated how steady-state substrate concentrations can change ultrasensitively in response to changes in their supply rates and how this is coupled to slow relaxation back to steady state after a perturbation. In the one-substrate system, such near-critical behavior occurs when the supply rate approaches the maximal elimination rate, and in the two-substrate system it occurs when the rates of substrate supply are almost balanced. As systems that operate near criticality tend to display large random fluctuations, we also carried out a stochastic analysis using analytical approximations of master equations and compared the results with molecular-level Monte Carlo simulations. It was found that the significance of random fluctuations was directly coupled to the steady-state sensitivity and that the two substrates can fluctuate greatly because they are anticorrelated in such a way that the product formation rate displays only small variation. Basic relations are highlighted and biological implications are discussed. PMID:12524272

  3. Near-critical point phenomena in fluids (19-IML-1)

    Science.gov (United States)

    Beysens, D.

    1992-01-01

    Understanding the effects of gravity is essential if the behavior of fluids is to be predicted in spacecraft and orbital stations, and, more generally, to give a better understanding of the hydrodynamics in these systems. An understanding is sought of the behavior of fluids in space. What should emerge from the International Microgravity Lab (IML-1) mission is a better understanding of the kinetics of growth in off-critical conditions, in both liquid mixtures and pure fluids. This complex phenomenon is the object of intensive study in physics and materials sciences area. It is also expected that the IML-1 flight will procure key results to provide a better understanding of how a pure fluid can be homogenized without gravity induced convections, and to what extent the 'Piston Effect' is effective in thermalizing the compressible fluids.

  4. Renormalization Group for Critical Phenomena in Complex Networks

    Science.gov (United States)

    Boettcher, S.; Brunson, C. T.

    2011-01-01

    We discuss the behavior of statistical models on a novel class of complex “Hanoi” networks. Such modeling is often the cornerstone for the understanding of many dynamical processes in complex networks. Hanoi networks are special because they integrate small-world hierarchies common to many social and economical structures with the inevitable geometry of the real world these structures exist in. In addition, their design allows exact results to be obtained with the venerable renormalization group (RG). Our treatment will provide a detailed, pedagogical introduction to RG. In particular, we will study the Ising model with RG, for which the fixed points are determined and the RG flow is analyzed. We show that the small-world bonds result in non-universal behavior. It is shown that a diversity of different behaviors can be observed with seemingly small changes in the structure of hierarchical networks generally, and we provide a general theory to describe our findings. PMID:22194725

  5. Fire phenomena and nonlinearity (II). Catastrophic fire dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Z. [University of Science and Technology, Hefei (China). State Key Laboratory of Fire Science

    2000-09-01

    As one of the most important non-linear mechanisms to cause fire or exacerbate fire disaster, there is a great deal of catastrophe behaviours existing in fire processes. The main tasks of the study of catastrophic fire dynamics are: 1) analysis of the catastrophe mechanisms of discontinuity behaviours in fire systems; 2) investigation of the controlling methods of discontinuity behaviours of fire system; 3) qualitative analysis of the dynamical characteristics of fire systems; and 4) catastrophe classifying of discontinuity phenomena in fire system. The other disciplines, such as physics, chemistry, biology, geoscience, astronomy, or even social sciences (for instance, political, economics, strategics and management science), may also take the similar method to establish the corresponding branch discipline of catastrophe science and catastrophe classification method. It is pointed out that an ignition behaviour of the uniform temperature thermal explosion system under the control of radiation has cusp catastrophe mechanism. 10 refs., 3 figs.

  6. Critical phenomena in a disc-percolation model and their application to relativistic heavy ion collisions

    Institute of Scientific and Technical Information of China (English)

    KE Hong-Wei; XU Ming-Mei; LIU Lian-Shou

    2009-01-01

    By studying the critical phenomena in continuum-percolation of discs, we find a new approach to locate the critical point, i.e.using the inflection point of P_∞ as an evaluation of the percolation threshold.The susceptibility, defined as the derivative of P_∞, possesses a finite-size scaling property, where the scaling exponent is the reciprocal of ν, the critical exponent of the correlation length.A possible application of this approach to the study of the critical phenomena in relativistic heavy ion collisions is discussed.The critical point for deconfinement can be extracted by the inflection point of P_(QGP)-the probability for the event with QGP formation.The finite-size scaling of its derivative can give the critical exponent ν, which is a rare case that can provide an experimental measure of a critical exponent in heavy ion collisions.

  7. Thermal dynamics of thermoelectric phenomena from frequency resolved methods

    Directory of Open Access Journals (Sweden)

    J. García-Cañadas

    2016-03-01

    Full Text Available Understanding the dynamics of thermoelectric (TE phenomena is important for the detailed knowledge of the operation of TE materials and devices. By analyzing the impedance response of both a single TE element and a TE device under suspended conditions, we provide new insights into the thermal dynamics of these systems. The analysis is performed employing parameters such as the thermal penetration depth, the characteristic thermal diffusion frequency and the thermal diffusion time. It is shown that in both systems the dynamics of the thermoelectric response is governed by how the Peltier heat production/absorption at the junctions evolves. In a single thermoelement, at high frequencies the thermal waves diffuse semi-infinitely from the junctions towards the half-length. When the frequency is reduced, the thermal waves can penetrate further and eventually reach the half-length where they start to cancel each other and further penetration is blocked. In the case of a TE module, semi-infinite thermal diffusion along the thickness of the ceramic layers occurs at the highest frequencies. As the frequency is decreased, heat storage in the ceramics becomes dominant and starts to compete with the diffusion of the thermal waves towards the half-length of the thermoelements. Finally, the cancellation of the waves occurs at the lowest frequencies. It is demonstrated that the analysis is able to identify and separate the different physical processes and to provide a detailed understanding of the dynamics of different thermoelectric effects.

  8. Thermal dynamics of thermoelectric phenomena from frequency resolved methods

    Science.gov (United States)

    García-Cañadas, J.; Min, G.

    2016-03-01

    Understanding the dynamics of thermoelectric (TE) phenomena is important for the detailed knowledge of the operation of TE materials and devices. By analyzing the impedance response of both a single TE element and a TE device under suspended conditions, we provide new insights into the thermal dynamics of these systems. The analysis is performed employing parameters such as the thermal penetration depth, the characteristic thermal diffusion frequency and the thermal diffusion time. It is shown that in both systems the dynamics of the thermoelectric response is governed by how the Peltier heat production/absorption at the junctions evolves. In a single thermoelement, at high frequencies the thermal waves diffuse semi-infinitely from the junctions towards the half-length. When the frequency is reduced, the thermal waves can penetrate further and eventually reach the half-length where they start to cancel each other and further penetration is blocked. In the case of a TE module, semi-infinite thermal diffusion along the thickness of the ceramic layers occurs at the highest frequencies. As the frequency is decreased, heat storage in the ceramics becomes dominant and starts to compete with the diffusion of the thermal waves towards the half-length of the thermoelements. Finally, the cancellation of the waves occurs at the lowest frequencies. It is demonstrated that the analysis is able to identify and separate the different physical processes and to provide a detailed understanding of the dynamics of different thermoelectric effects.

  9. Critical Behaviors in Contagion Dynamics

    Science.gov (United States)

    Böttcher, L.; Nagler, J.; Herrmann, H. J.

    2017-02-01

    We study the critical behavior of a general contagion model where nodes are either active (e.g., with opinion A , or functioning) or inactive (e.g., with opinion B , or damaged). The transitions between these two states are determined by (i) spontaneous transitions independent of the neighborhood, (ii) transitions induced by neighboring nodes, and (iii) spontaneous reverse transitions. The resulting dynamics is extremely rich including limit cycles and random phase switching. We derive a unifying mean-field theory. Specifically, we analytically show that the critical behavior of systems whose dynamics is governed by processes (i)-(iii) can only exhibit three distinct regimes: (a) uncorrelated spontaneous transition dynamics, (b) contact process dynamics, and (c) cusp catastrophes. This ends a long-standing debate on the universality classes of complex contagion dynamics in mean field and substantially deepens its mathematical understanding.

  10. General description of quasiadiabatic dynamical phenomena near exceptional points

    Science.gov (United States)

    Milburn, Thomas J.; Doppler, Jörg; Holmes, Catherine A.; Portolan, Stefano; Rotter, Stefan; Rabl, Peter

    2015-11-01

    The appearance of so-called exceptional points in the complex spectra of non-Hermitian systems is often associated with phenomena that contradict our physical intuition. One example of particular interest is the state-exchange process predicted for an adiabatic encircling of an exceptional point. In this work we analyze this and related processes for the generic system of two coupled oscillator modes with loss or gain. We identify a characteristic system evolution consisting of periods of quasistationarity interrupted by abrupt nonadiabatic transitions and we present a qualitative and quantitative description of this switching behavior by connecting the problem to the phenomenon of stability loss delay. This approach makes accurate predictions for the breakdown of the adiabatic theorem as well as the occurrence of chiral behavior observed previously in this context and provides a general framework to model and understand quasiadiabatic dynamical effects in non-Hermitian systems.

  11. Some optical and dynamical phenomena in the Rindler model

    CERN Document Server

    Birsin, E

    2014-01-01

    In Rindler's model of a uniformly accelerated reference frame we analyze the apparent shape of rods and marked light rays for the case that the observers as well as the rods and the sources of light are at rest with respect to the Rindler observers. Contrary to the expectation suggested by the strong principle of equivalence, there is no apparent "bending down" of a light ray with direction transversal to the direction of acceleration, but a straight rod oriented orthogonal to the direction of acceleration appears bended "upwards". These optical phenomena are in accordance with the dynamical experience of observers guided by a straight track or a track curved in the same way as the marked light ray, respectively: While the former observer feels a centrifugal force directed "downwards", the centrifugal force for the latter vanishes. The properties of gyroscope transport along such tracks are correspondingly.

  12. Nonlinear dynamics of drops and bubbles and chaotic phenomena

    Science.gov (United States)

    Trinh, Eugene H.; Leal, L. G.; Feng, Z. C.; Holt, R. G.

    1994-01-01

    Nonlinear phenomena associated with the dynamics of free drops and bubbles are investigated analytically, numerically and experimentally. Although newly developed levitation and measurement techniques have been implemented, the full experimental validation of theoretical predictions has been hindered by interfering artifacts associated with levitation in the Earth gravitational field. The low gravity environment of orbital space flight has been shown to provide a more quiescent environment which can be utilized to better match the idealized theoretical conditions. The research effort described in this paper is a closely coupled collaboration between predictive and guiding theoretical activities and a unique experimental program involving the ultrasonic and electrostatic levitation of single droplets and bubbles. The goal is to develop and to validate methods based on nonlinear dynamics for the understanding of the large amplitude oscillatory response of single drops and bubbles to both isotropic and asymmetric pressure stimuli. The first specific area on interest has been the resonant coupling between volume and shape oscillatory modes isolated gas or vapor bubbles in a liquid host. The result of multiple time-scale asymptotic treatment, combined with domain perturbation and bifurcation methods, has been the prediction of resonant and near-resonant coupling between volume and shape modes leading to stable as well as chaotic oscillations. Experimental investigations of the large amplitude shape oscillation modes of centimeter-size single bubbles trapped in water at 1 G and under reduced hydrostatic pressure, have suggested the possibility of a low gravity experiment to study the direct coupling between these low frequency shape modes and the volume pulsation, sound-radiating mode. The second subject of interest has involved numerical modeling, using the boundary integral method, of the large amplitude shape oscillations of charged and uncharged drops in the presence

  13. Soft-Cliff Retreat, Self-Organized Critical Phenomena in the Limit of Predictability?

    Science.gov (United States)

    Paredes, Carlos; Godoy, Clara; Castedo, Ricardo

    2015-03-01

    The coastal erosion along the world's coastlines is a natural process that occurs through the actions of marine and subaerial physico-chemical phenomena, waves, tides, and currents. The development of cliff erosion predictive models is limited due to the complex interactions between environmental processes and material properties over a wide range of temporal and spatial scales. As a result of this erosive action, gravity driven mass movements occur and the coastline moves inland. Like other studied earth natural and synthetically modelled phenomena characterized as self-organized critical (SOC), the recession of the cliff has a seemingly random, sporadic behavior, with a wide range of yearly recession rate values probabilistically distributed by a power-law. Usually, SOC systems are defined by a number of scaling features in the size distribution of its parameters and on its spatial and/or temporal pattern. Particularly, some previous studies of derived parameters from slope movements catalogues, have allowed detecting certain SOC features in this phenomenon, which also shares the recession of cliffs. Due to the complexity of the phenomenon and, as for other natural processes, there is no definitive model of recession of coastal cliffs. In this work, various analysis techniques have been applied to identify SOC features in the distribution and pattern to a particular case: the Holderness shoreline. This coast is a great case study to use when examining coastal processes and the structures associated with them. It is one of World's fastest eroding coastlines (2 m/yr in average, max observed 22 m/yr). Cliffs, ranging from 2 m up to 35 m in height, and made up of glacial tills, mainly compose this coast. It is this soft boulder clay that is being rapidly eroded and where coastline recession measurements have been recorded by the Cliff Erosion Monitoring Program (East Riding of Yorkshire Council, UK). The original database has been filtered by grouping contiguous

  14. Critical phenomena in ethylbenzene oxidation in acetic acid solution at high cobalt(II) concentrations

    NARCIS (Netherlands)

    Gavrichkov, AA; Zakharov, [No Value

    2005-01-01

    Critical phenomena in ethylbenzene oxidation in an acetic acid solution at high cobalt(ill) concentrations (from 0.01 to 0.2 mol L-1) were studied at 60-90 degrees C by the gasometric (O-2 absorption), spectrophotometric (Co-III accumulation), and chemiluminescence (relative concentration of radical

  15. Using Compression Isotherms of Phospholipid Monolayers to Explore Critical Phenomena: A Biophysical Chemistry Experiment

    Science.gov (United States)

    Gragson, Derek E.; Beaman, Dan; Porter, Rhiannon

    2008-01-01

    Two experiments are described in which students explore phase transitions and critical phenomena by obtaining compression isotherms of phospholipid monolayers using a Langmuir trough. Through relatively simple analysis of their data students gain a better understanding of compression isotherms, the application of the Clapeyron equation, the…

  16. Generalized scaling theory for critical phenomena including essential singularities and infinite dimensionality.

    Science.gov (United States)

    Nogawa, Tomoaki; Hasegawa, Takehisa; Nemoto, Koji

    2012-06-22

    We propose a generic scaling theory for critical phenomena that includes power-law and essential singularities in finite and infinite dimensional systems. In addition, we clarify its validity by analyzing the Potts model in a simple hierarchical network, where a saddle-node bifurcation of the renormalization-group fixed point governs the essential singularity.

  17. Quantum dynamical phenomena of independent electrons in semiconductor superlattices subject to a uniform electric field

    Energy Technology Data Exchange (ETDEWEB)

    Bouchard, A.M.

    1994-07-27

    This report discusses the following topics: Bloch oscillations and other dynamical phenomena of electrons in semiconductor superlattices; solvable dynamical model of an electron in a one-dimensional aperiodic lattice subject to a uniform electric field; and quantum dynamical phenomena of electrons in aperiodic semiconductor superlattices.

  18. Modeling of mesoscopic electrokinetic phenomena using charged dissipative particle dynamics

    Science.gov (United States)

    Deng, Mingge; Li, Zhen; Karniadakis, George

    2015-11-01

    In this work, we propose a charged dissipative particle dynamics (cDPD) model for investigation of mesoscopic electrokinetic phenomena. In particular, this particle-based method was designed to simulate micro- or nano- flows which governing by Poisson-Nernst-Planck (PNP) equation coupled with Navier-Stokes (NS) equation. For cDPD simulations of wall-bounded fluid systems, a methodology for imposing correct Dirichlet and Neumann boundary conditions for both PNP and NS equations is developed. To validate the present cDPD model and the corresponding boundary method, we perform cDPD simulations of electrostatic double layer (EDL) in the vicinity of a charged wall, and the results show good agreement with the mean-field theoretical solutions. The capacity density of a parallel plate capacitor in salt solution is also investigated with different salt concentration. Moreover, we utilize the proposed methodology to study the electroosmotic and electroosmotic/pressure-driven flow in a micro-channel. In the last, we simulate the dilute polyelectrolyte solution both in bulk and micro-channel, which show the flexibility and capability of this method in studying complex fluids. This work was sponsored by the Collaboratory on Mathematics for Mesoscopic Modeling of Materials (CM4) supported by DOE.

  19. Molecular dynamics simulation for aggregation phenomena of nanocolloids

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Nonequilibrium molecular dynamics (MD) method was used to study the dielectrophoresis (DEP) motion of nanocolloids in non-uniform electric field. By changing the electric field strength and system temperature, aggregation phenomena of nanocolloids was analyzed. Simulation results showed that at normal temperature, though the Brownian force can affect the motion of colloids, the attractive force will increase quickly with the distance between colloids down to 12σ , which makes colloids aggregate. When the Brownian force is weak to colloid’s motion, for the enhancement of electric field strength, the DEP force of colloid will increase and so did the attractive force, which finally quickens the aggregate speed. Simulation results also showed that the temperature’ enhancement will increase the Brownian force of colloids, hence disturbing the colloids aggregation. Moreover, the DLVO theory was used to study the motion of a pair of interactional colloids, both the potential energy and the attractive force versus distance of colloids were presented, then the latter graph was used to compare with another graph elicited by MD method. Results showed that the two graphs were nearly the same, indicating the MD model accorded with the theory.

  20. Molecular dynamics simulation for agggregation phenomena of nanocolloids

    Institute of Scientific and Technical Information of China (English)

    NI ZhongHua; ZHANG XinJie

    2009-01-01

    Nonequilibrium molecular dynamics (MD) method was used to study the dielectrophoresis (DEP) mo-tion of nanocolioids in non-uniform electric field. By changing the electric field strength and system temperature, aggregation phenomena of nanocolloids was analyzed. Simulation results showed that at normal temperature, though the Brownian force can affect the motion of colloids, the attractive force will increase quickly with the distance between colloids down to 12 σ, which makes colloids aggregate. When the Brownian force is weak to colloid's motion, for the enhancement of electric field strength, the DEP force of colloid will increase and so did the attractive force, which finally quickens the aggregate speed. Simulation results also showed that the temperature' enhancement will increase the Brownian force of colloids, hence disturbing the colloids aggregation. Moreover, the DLVO theory was used to study the motion of a pair of interactional colloids, both the potential energy and the attractive force versus distance of colloids were presented, then the latter graph was used to compare with another graph elicited by MD method. Results showed that the two graphs were nearly the same, indicating the MD model accorded with the theory.

  1. Dynamic Phenomena in Laser Cutting and Process Performance

    Science.gov (United States)

    Schuöcker, Dieter; Aichinger, Joachim; Majer, Richard

    Laser cutting of sheet metals is widely used all over the world since it combines high speed with excellent cutting quality. Nevertheless if the thickness of the work piece becomes relatively high, the roughness of the cut edges becomes quite coarse and also the formation of dross and slag is likely. The latter phenomena must obviously be related to dynamic processes that can be identified as fluctuations in the liquid body that forms at the current end of the cut due to absorption of laser radiation and where material removal takes place due to friction with a sharply focused gas jet. A detailed analysis of the liquid layer shows that viscosity and surface tension that have so far not been considered very often in the literature have a strong impact on the material removal mechanism which consists of the formation and separation of droplets formed at the bottom of the work piece, thus being essentially intermittent. The mathematical treatment of this model shows good coincidence with experimental data. It gives rise to the idea that a substantial reduction of surface tension could improve the material removal mechanism insofar as the intermittent ejection is transformed into a continuous ejection of melt flow thus considerably improving cutting speed and quality. These ideas have also led to a new patent for an improved laser cutting head.

  2. Freezing in porous media: Phase behavior, dynamics and transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Wettlaufer, John S. [Yale Univ., New Haven, CT (United States)

    2012-12-21

    This research was focused on developing the underlying framework for the mechanisms that control the nature of the solidification of a broad range of porous media. To encompass the scope of porous media under consideration we considered material ranging from a dilute colloidal suspension to a highly packed saturated host matrix with a known geometry. The basic physical processes that occur when the interstitial liquid phase solidifies revealed a host of surprises with a broad range of implications from geophysics to materials science and engineering. We now understand that ostensibly microscopic films of unfrozen liquid control both the equilibrium and transport properties of a highly packed saturated host matrix as well as a rather dilute colloidal suspension. However, our description of the effective medium behavior in these settings is rather different and this sets the stage for the future research based on our past results. Once the liquid phase of a saturated relatively densely packed material is frozen, there is a rich dynamical behavior of particles for example due to the directed motion driven by thermomolecular pressure gradients or the confined Brownian motion of the particles. In quite striking contrast, when one freezes a dilute suspension the behavior can be rather more like that of a binary alloy with the particles playing the role of a ``solute''. We probed such systems quantitatively by (i) using X ray photon correlation spectroscopy (XPCS) and Small Angle X-ray Scattering (SAXS) at the Advanced Photon Source at Argonne (ii) studying the Argonne cell in the laboratory using optical microscopy and imagery (because it is not directly visible while in the vacuum can). (3) analyzed the general transport phenomena within the framework of both irreversible thermodynamics and alloy solidification and (4) applied the results to the study of the redistribution of solid particles in a frozen interstitial material. This research has gone a long way

  3. Freezing in porous media: Phase behavior, dynamics and transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Wettlaufer, John S. [Yale Univ., New Haven, CT (United States)

    2012-12-21

    This research was focused on developing the underlying framework for the mechanisms that control the nature of the solidification of a broad range of porous media. To encompass the scope of porous media under consideration we considered material ranging from a dilute colloidal suspension to a highly packed saturated host matrix with a known geometry. The basic physical processes that occur when the interstitial liquid phase solidifies revealed a host of surprises with a broad range of implications from geophysics to materials science and engineering. We now understand that ostensibly microscopic films of unfrozen liquid control both the equilibrium and transport properties of a highly packed saturated host matrix as well as a rather dilute colloidal suspension. However, our description of the effective medium behavior in these settings is rather different and this sets the stage for the future research based on our past results. Once the liquid phase of a saturated relatively densely packed material is frozen, there is a rich dynamical behavior of particles for example due to the directed motion driven by thermomolecular pressure gradients or the confined Brownian motion of the particles. In quite striking contrast, when one freezes a dilute suspension the behavior can be rather more like that of a binary alloy with the particles playing the role of a ``solute''. We probed such systems quantitatively by (i) using X ray photon correlation spectroscopy (XPCS) and Small Angle X-ray Scattering (SAXS) at the Advanced Photon Source at Argonne (ii) studying the Argonne cell in the laboratory using optical microscopy and imagery (because it is not directly visible while in the vacuum can). (3) analyzed the general transport phenomena within the framework of both irreversible thermodynamics and alloy solidification and (4) applied the results to the study of the redistribution of solid particles in a frozen interstitial material. This research has gone a long way

  4. Critical thinking of destabilizing interpretations of events and phenomena: the role of economic sciences

    Directory of Open Access Journals (Sweden)

    Тетяна Андріївна Непокупна

    2015-03-01

    Full Text Available This article analyzes the global transformations and their impact on the main society life; the specifics of modern interpretations of events and phenomena, their destabilizing effects on behavior, health and life of humans; the role of economic sciences in the formation of critical thinking as a means of combating ignorance and propaganda, formation of an objective world view that grounded on knowledge

  5. Critical Phenomena in Higher Curvature Charged AdS Black Holes

    Directory of Open Access Journals (Sweden)

    Arindam Lala

    2013-01-01

    Full Text Available In this paper, we have studied the critical phenomena in higher curvature charged AdS black holes. We have considered Lovelock-Born-Infeld-AdS black hole as an example. The thermodynamics of the black hole have been studied which reveals the onset of a higher-order phase transition in the black hole in the canonical ensemble (fixed charge ensemble framework. We have analytically derived the critical exponents associated with these thermodynamic quantities. We find that our results fit well with the thermodynamic scaling laws and consistent with the mean field theory approximation. The suggestive values of the other two critical exponents associated with the correlation function and correlation length on the critical surface have been derived.

  6. Critical phenomena of asymmetric nuclear matter in the extended Zimanyi-Moszkowski model

    CERN Document Server

    Miyazaki, K

    2005-01-01

    We have studied the liquid-gas phase transition of warm asymmetric nuclear matter in the extended Zimanyi-Moszkowski model. The three sets of the isovector-meson coupling constants are used. It is found that the critical temperature depends only on the difference of the symmetry energy but not on the differences of each isovector coupling constant. We treat the asymmetric nuclear matter as one-component system and employ the Maxwell construction so as to calculate the liquid-gas phase coexistence curve. The derived critical exponents depend on neither the symmetry energy nor the asymmetry of the system. Their values beta=0.33 and gamma=1.21 agree with the empirical values derived from the recent multifragmentation reactions. Consequently, we have confirmed the universality of the critical phenomena in the liquid-gas phase transition of nuclear matter.

  7. Critical phenomena of strange hadronic matter in the extended Zimanyi-Moszkowski model

    CERN Document Server

    Miyazaki, K

    2005-01-01

    We have studied the liquid-gas phase transition of warm strange hadronic matter (SHM) in the extended Zimanyi-Moszkowski model. We implement the Nijmegen soft-core potential model NSC97f of hyperon-hyperon interactions in terms of the (hidden) strange mesons. The saturation properties of pure Lambda and Xi matter by the potential essentially determine the dependence of the critical temperature on the strangeness fraction of SHM. We treat the liquid-gas phase transition of SHM as the first-order one and employ Maxwell construction so as to calculate the phase coexistence curves. The derived critical exponents beta \\simeq 1/3 and gamma=1.22 are almost independent of the strangeness fraction of SHM and almost agree with the empirical values derived from the recent multifragmentation reactions. Consequently, we have confirmed the universality of the critical phenomena in the liquid-gas phase transition of hadronic system.

  8. Modeling friction phenomena and elastomeric dampers in multibody dynamics analysis

    Science.gov (United States)

    Ju, Changkuan

    The first part of this dissertation focuses on the development, implementation and validation of models that capture the behavior of joints in a realistic manner. These models are presented within the framework of finite element based, nonlinear multibody dynamics formulations that ensure unconditional nonlinear stability of the computation for complex systems of arbitrary topology. The proposed approach can be divided into three parts. First, the joint configuration: this purely kinematic part deals with the description of the configuration of the joint and the evaluation of the relative distance and relative tangential velocity between the contacting bodies. Second, the contact conditions: in most cases, contact at the joint is of an intermittent nature. The enforcement of the unilateral contact condition is a critical aspect of the computational procedure. And finally, the contact forces: this last part deals with the evaluation of the forces that arise at the interface between contacting bodies. The advantage of the proposed approach is that the three parts of the problem can be formulated and implemented independently. Many articulated rotor helicopters use hydraulic dampers, which provide high levels of damping but are also associated with high maintenance costs and difficulties in evaluating their conditions due to the presence of seals, lubricants and numerous moving parts, all operating in a rotating frame. To avoid problems associated with hydraulic dampers, the industry is now switching to elastomeric lead-lag dampers that feature simpler mechanical design, lower part count, and result in "dry" rotors. However, the design of robust elastomeric dampers is hampered by the lack of reliable analytical tools that can be used to predict their damping behavior in the presence of large multi-frequency motions experienced by the rotor and thus the damper. The second part of this dissertation focuses on the development of an elastomeric damper model which predicts

  9. Basic tasks for improving spectral-acoustic forecasting of dynamic phenomena in coal mines

    Science.gov (United States)

    Shadrin, A. V.; Kontrimas, A. A.

    2017-09-01

    A number of tasks for improving the spectral-acoustic method for forecasting dynamic phenomena and controlling stress condition in coalmines is considered. They are: considering the influence of a gas factor on the danger indicator, dependence of a relative pressure coefficient on the distance between the source and the receiver of the probing acoustic signal, correct selection of operating frequencies, the importance of developing the techniques for defining the critical value of the outburst danger index The influence of the rock mass stress condition ahead of the preliminary opening face on the relative pressure coefficient defined for installing the sound receiver in the wall of the opening behind the opening face is also justified in the article.

  10. Critical phenomena in higher curvature charged AdS black holes

    CERN Document Server

    Lala, Arindam

    2012-01-01

    In this paper we have studied the critical phenomena in higher curvature charged black holes in the anti-de Sitter (AdS) space-time. As an example we have considered the third order Lovelock-Born-Infeld black holes in AdS space-time. We have analytically derived the thermodynamic quantities of the system. Our analysis revealed the onset of a higher order phase transition in the black hole leading to an infinite discontinuity in the specific heat at constant charge at the critical points. Our entire analysis is based on the canonical framework where we have fixed the charge of the black hole. In an attempt to study the behavior of the thermodynamic quantities near the critical points we have derived the critical exponents of the system explicitly. Although the values of the critical points have been determined numerically, the critical exponents are calculated analytically. Our results fit well with the thermodynamic scaling laws. The scaling hypothesis is also seen to be consistent with these scaling laws. We...

  11. Dimension dependence of the critical phenomena in gravitational collapse of massless scalar field

    Science.gov (United States)

    Bland, Jason Bryan

    2007-12-01

    A study of the critical behaviour which is observed in numerical calculations of spherically symmetric scalar field collapse has been performed. The gravitational collapse calculations are carried out using the field equations of Einstein's general theory of relativity in the context of a two dimensional dilaton gravity theory. The problem is formulated by considering a spherically symmetric matter distribution in an arbitrary number of space-time dimensions greater than three. A spherical distribution will only depend on two space-time coordinates, therefore, the action of the model can be reduced to a specific case of a 1 + 1 dilaton gravity theory. The evolution equations of the problem are simplified by carrying out a conformal transformation of the metric field. The number of space-time dimensions then appears as an input parameter of the field equations. Initial data is defined on a discrete space-time grid and numerical simulations of gravitational collapse are carried out. The computer code is optimized to increase numerical stability near the critical solutions. Discrete self-similarity and mass scaling in the near critical solutions are observed for each of the dimensions studied. The critical phenomena are described with a high level of confidence by smooth functions of space-time dimension. It is hypothesized that the critical solution of the theory at the limit of large dimension is discretely self-similar with a period of 5/2 and contains critical scaling with a constant of 1/2. Evidence will also be presented which suggests the critical solution in three dimensions with zero cosmological constant is not discretely self-similar but contains a critical scaling constant of approximately 0.11.

  12. Paranormal phenomena

    Science.gov (United States)

    Gaina, Alex

    1996-08-01

    Critical analysis is given of some paranormal phenomena events (UFO, healers, psychokinesis (telekinesis))reported in Moldova. It is argued that correct analysis of paranormal phenomena should be made in the framework of electromagnetism.

  13. On time-space of nonlinear phenomena with Gompertzian dynamics.

    Science.gov (United States)

    Waliszewski, Przemyslaw; Konarski, Jerzy

    2005-04-01

    This paper describes a universal relationship between time and space for a nonlinear process with Gompertzian dynamics, such as growth. Gompertzian dynamics implicates a coupling between time and space. Those two categories are related to each other through a linear function of their logarithms. Moreover, we demonstrate that the spatial fractal dimension is a function of both scalar time and the temporal fractal dimension. The Gompertz function reflects the equilibrium of regular states, that is, states with dynamics that are predictable for any time-point (e.g., sinusoidal glycolytic oscillations) and chaotic states, that is, states with dynamics that are unpredictable in time, but are characterized by certain regularities (e.g., the existence of strange attractor for any biochemical reaction). We conclude that both this equilibrium and volume of the available complementary Euclidean space determine temporal and spatial expansion of a process with Gompertzian dynamics.

  14. Microscopic approach to critical phenomena at interfaces: An application to complete wetting in the Ising model

    Science.gov (United States)

    Orlandi, A.; Parola, A.; Reatto, L.

    2004-11-01

    We study how the formalism of the hierarchical reference theory (HRT) can be extended to inhomogeneous systems. HRT is a liquid-state theory which implements the basic ideas of the Wilson momentum-shell renormalization group (RG) to microscopic Hamiltonians. In the case of homogeneous systems, HRT provides accurate results even in the critical region, where it reproduces scaling and nonclassical critical exponents. We applied the HRT to study wetting critical phenomena in a planar geometry. Our formalism avoids the explicit definition of effective surface Hamiltonians but leads, close to the wetting transition, to the same renormalization group equation already studied by RG techiques. However, HRT also provides information on the nonuniversal quantities because it does not require any preliminary coarse graining procedure. A simple approximation to the infinite HRT set of equations is discussed. The HRT evolution equation for the surface free energy is numerically integrated in a semi-infinite three-dimensional Ising model and the complete wetting phase transition is analyzed. A renormalization of the adsorption critical amplitude and of the wetting parameter is observed. Our results are compared to available Monte Carlo simulations.

  15. On the Thermodynamic Geometry and Critical Phenomena of AdS Black Holes

    CERN Document Server

    Sahay, Anurag; Sengupta, Gautam

    2010-01-01

    In this paper, we study various aspects of the equilibrium thermodynamic state space geometry of AdS black holes. We first examine the Reissner-Nordstrom-AdS (RN-AdS) and the Kerr-AdS black holes. In this context, the state space scalar curvature of these black holes are analysed in various regions of their thermodynamic parameter space. This provides important new insights into the structure and significance of the scalar curvature. We further investigate critical phenomena, and the behaviour of the scalar curvature near criticality, for KN-AdS black holes in two mixed ensembles, introduced and elucidated in our earlier work arXiv:1002.2538 [hep-th]. The critical exponents are identical to those in the RN-AdS and Kerr-AdS cases in the canonical ensemble. This suggests an universality in the scaling behaviour near critical points of AdS black holes. Our results further highlight qualitative differences in the thermodynamic state space geometry for electric charge and angular momentum fluctuations of these.

  16. Theory of non-equilibrium critical phenomena in three-dimensional condensed systems of charged mobile nanoparticles.

    Science.gov (United States)

    Kuzovkov, V N; Zvejnieks, G; Kotomin, E A

    2014-07-21

    A study of 3d electrostatic self-assembly (SA) in systems of charged nanoparticles (NPs) is one of the most difficult theoretical problems. In particular, the limiting case of negligible or very low polar media (e.g. salt) concentration, where the long-range NP interactions cannot be reduced to commonly used effective short-range (Yukawa) potentials, remains unstudied. Moreover, the present study has demonstrated that unlike the Debye-Hückel theory, a complete screening of the charges in SA kinetics (dynamic SA) is not always possible. Generally speaking, one has to take into account implicitly how each NP interacts with all other NPs (the true long-range interactions). Traditional theoretical methods allow us to monitor such electrostatic 3d system kinetics only for very short times, which is far from sufficient for understanding the dynamic SA. In this paper, combining an integrated analytical approach (the non-linear integro-differential kinetic equation for correlation functions) and reverse Monte Carlo in the 3d case, we have obtained a self-consistent solution of this challenging problem. We demonstrate, in particular, the existence of critical points and critical phenomena in the non-equilibrium kinetics in a 3d system of oppositely charged mobile NPs.

  17. Dynamics of epileptic phenomena determined from statistics of ictal transitions

    NARCIS (Netherlands)

    Suffczynski, P.; Silva, F.H.L. da; Parra, J.; Velis, D.N.; Bouwman, B.M.; Rijn, C.M. van; Hese, P. van; Boon, P.; Khosravani, H.; Derchansky, M.; Carlen, P.; Kalitzin, S.

    2006-01-01

    In this paper, we investigate the dynamical scenarios of transitions between normal and paroxysmal state in epilepsy. We assume that some epileptic neural network are bistable i.e., they feature two operational states, ictal and interictal that co-exist. The transitions between these two states may

  18. PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids

    Science.gov (United States)

    Chen, Sow-Hsin; Baglioni, Piero

    2012-02-01

    This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the

  19. An alternative perspective to observe the critical phenomena of dilaton black holes

    Science.gov (United States)

    Mo, Jie-Xiong

    2017-08-01

    The critical phenomena of dilaton black holes are probed from a totally different perspective other than the P- v criticality and the q- U criticality discussed in former literature. We investigate not only the two point correlation function but also the entanglement entropy of dilaton black holes. For both the two point correlation function and the entanglement entropy we consider 4× 2× 2=16 cases due to different choices of parameters. The van der Waals-like behavior can be clearly witnessed from all the T-δ L ( T-δ S) graphs for qgravity and the spacetime dimensionality on the phase structure of dilaton black holes are disclosed. Furthermore, we discuss the stability of dilaton black holes by applying the analogous specific heat definition and remove the unstable branch by introducing a bar T=T_*. It is shown that the first order phase transition temperature T_* is affected by both α and n. The analogous equal area laws for both the T-δ L graph and the T-δ S graph are examined numerically. The relative errors for all cases are small enough so that we can safely conclude that the analogous equal area laws hold for T-δ L ( T-δ S) graph of dilaton black holes.

  20. An alternative perspective to observe the critical phenomena of dilaton AdS black holes

    CERN Document Server

    Mo, Jie-Xiong

    2016-01-01

    The critical phenomena of dilaton AdS black holes are probed from a totally different perspective other than the $P-v$ criticality and the $q-U$ criticality discussed in the former literature. We investigate not only the two point correlation function but also the entanglement entropy of dilaton AdS black holes. We achieve this goal by solving the equation of motion constrained by the boundary condition numerically and we concentrate on $\\delta L$ and $\\delta S$ which have been regularized by subtracting the terms in pure AdS with the same boundary region. For both the two point correlation function and the entanglement entropy, we consider $4\\times2\\times2=16$ cases due to different choices of parameters. The van der Waals like behavior can be clearly witnessed from all the $T-\\delta L$ ($T-\\delta S$) graphs for $q

  1. Critical phenomena of regular black holes in anti-de Sitter space-time

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Zhong-Ying [Peking University, Center for High Energy Physics, Beijing (China)

    2017-04-15

    In General Relativity, addressing coupling to a non-linear electromagnetic field, together with a negative cosmological constant, we obtain the general static spherical symmetric black hole solution with magnetic charges, which is asymptotic to anti-de Sitter (AdS) space-times. In particular, for a degenerate case the solution becomes a Hayward-AdS black hole, which is regular everywhere in the full space-time. The existence of such a regular black hole solution preserves the weak energy condition, while the strong energy condition is violated. We then derive the first law and the Smarr formula of the black hole solution. We further discuss its thermodynamic properties and study the critical phenomena in the extended phase space where the cosmological constant is treated as a thermodynamic variable as well as the parameter associated with the non-linear electrodynamics. We obtain many interesting results such as: the Maxwell equal area law in the P-V (or S-T) diagram is violated and consequently the critical point (T{sub *},P{sub *}) of the first order small-large black hole transition does not coincide with the inflection point (T{sub c},P{sub c}) of the isotherms; the Clapeyron equation describing the coexistence curve of the Van der Waals (vdW) fluid is no longer valid; the heat capacity at constant pressure is finite at the critical point; the various exponents near the critical point are also different from those of the vdW fluid. (orig.)

  2. Critical phenomena in communication/computation networks with various topologies and suboptimal to optimal resource allocation

    Science.gov (United States)

    Cogoni, Marco; Busonera, Giovanni; Anedda, Paolo; Zanetti, Gianluigi

    2015-01-01

    We generalize previous studies on critical phenomena in communication networks [1,2] by adding computational capabilities to the nodes. In our model, a set of tasks with random origin, destination and computational structure is distributed on a computational network, modeled as a graph. By varying the temperature of a Metropolis Montecarlo, we explore the global latency for an optimal to suboptimal resource assignment at a given time instant. By computing the two-point correlation function for the local overload, we study the behavior of the correlation distance (both for links and nodes) while approaching the congested phase: a transition from peaked to spread g(r) is seen above a critical (Montecarlo) temperature Tc. The average latency trend of the system is predicted by averaging over several network traffic realizations while maintaining a spatially detailed information for each node: a sharp decrease of performance is found over Tc independently of the workload. The globally optimized computational resource allocation and network routing defines a baseline for a future comparison of the transition behavior with respect to existing routing strategies [3,4] for different network topologies.

  3. Critical phenomena of regular black holes in anti-de Sitter space-time

    CERN Document Server

    Fan, Zhong-Ying

    2016-01-01

    In General Relativity coupled to a non-linear electromagnetic field, together with a negative cosmological constant, we obtain the general static spherical symmetric black hole solution with magnetic charges, which is asymptotic to anti-de Sitter (AdS) space-times. In particular, for a degenerate case the solution becomes a Hayward-AdS black hole, which is regular everywhere in the full space-time. The existence of such a regular black hole solution preserves the weak energy condition while the strong energy condition is violated. We then derive the first law and the Smarr formula of the black hole solution. We further discuss its thermodynamic properties and study the critical phenomena in the extended phase space where the cosmological constant is treated as a thermodynamic variable as well as the parameter associated with the non-linear electrodynamics. We obtain many interesting results such as: the Maxwell's equal area law in the $P-V$ (or $S-T$) diagram is violated and consequently the critical point $(...

  4. Can molecular dynamics help in understanding dielectric phenomena?

    Science.gov (United States)

    Olmi, Roberto; Bittelli, Marco

    2017-01-01

    Molecular dynamics (MD) is a modeling technique widely used in material science as well as in chemical physics, biochemistry and biophysics. MD is based on ‘first principles’, allowing one to compute the physical characteristics of a material, such as density, heat capacity, isothermal compressibility and also the dielectric constant and relaxation, mixing a classical physics approach and statistical mechanics. Although a number of papers exist in the literature concerning the study of the dielectric properties of liquid and solid materials, the MD approach appears to be almost ignored in the electromagnetic aquametry community. We use a rather simple example, a mixture of ethanol and water at various concentrations, to introduce MD as a theoretical tool for investigating the dielectric behavior of more complex moist substances. We show that MD simulations suggest a time-domain model for alcohol-water solutions, consisting in a mixture of a KWW stretched-exponential and a simple exponential, whose validity could be subjected to an experimental verification.

  5. BOOK REVIEW: Critical Phenomena in Natural Sciences: Chaos, Fractals, Selforganization and Disorder: Concepts and Tools

    Science.gov (United States)

    Franz, S.

    2004-10-01

    Since the discovery of the renormalization group theory in statistical physics, the realm of applications of the concepts of scale invariance and criticality has pervaded several fields of natural and social sciences. This is the leitmotiv of Didier Sornette's book, who in Critical Phenomena in Natural Sciences reviews three decades of developments and applications of the concepts of criticality, scale invariance and power law behaviour from statistical physics, to earthquake prediction, ruptures, plate tectonics, modelling biological and economic systems and so on. This strongly interdisciplinary book addresses students and researchers in disciplines where concepts of criticality and scale invariance are appropriate: mainly geology from which most of the examples are taken, but also engineering, biology, medicine, economics, etc. A good preparation in quantitative science is assumed but the presentation of statistical physics principles, tools and models is self-contained, so that little background in this field is needed. The book is written in a simple informal style encouraging intuitive comprehension rather than stressing formal derivations. Together with the discussion of the main conceptual results of the discipline, great effort is devoted to providing applied scientists with the tools of data analysis and modelling necessary to analyse, understand, make predictions and simulate systems undergoing complex collective behaviour. The book starts from a purely descriptive approach, explaining basic probabilistic and geometrical tools to characterize power law behaviour and scale invariant sets. Probability theory is introduced by a detailed discussion of interpretative issues warning the reader on the use and misuse of probabilistic concepts when the emphasis is on prediction of low probability rare---and often catastrophic---events. Then, concepts that have proved useful in risk evaluation, extreme value statistics, large limit theorems for sums of independent

  6. Critical slowing down in a dynamic duopoly

    Science.gov (United States)

    Escobido, M. G. O.; Hatano, N.

    2015-01-01

    Anticipating critical transitions is very important in economic systems as it can mean survival or demise of firms under stressful competition. As such identifying indicators that can provide early warning to these transitions are very crucial. In other complex systems, critical slowing down has been shown to anticipate critical transitions. In this paper, we investigate the applicability of the concept in the heterogeneous quantity competition between two firms. We develop a dynamic model where the duopoly can adjust their production in a logistic process. We show that the resulting dynamics is formally equivalent to a competitive Lotka-Volterra system. We investigate the behavior of the dominant eigenvalues and identify conditions that critical slowing down can provide early warning to the critical transitions in the dynamic duopoly.

  7. Critical dynamics and global persistence exponent on Taiwan financial market

    CERN Document Server

    Chen, I C; Li, P C; Chen, H J; Tseng, Hsen-Che; Li, Ping-Cheng; Chen, Hung-Jung

    2006-01-01

    We investigated the critical dynamics on the daily Taiwan stock exchange index (TSE) from 1971 to 2005, and the 5-min intraday data from 1996 to 2005. A global persistence exponent $\\theta_{p}$ was defined for non-equilibrium critical phenomena \\cite{Janssen,Majumdar}, and describing dynamic behavior in an economic index \\cite{Zheng}. In recent numerical analysis studies of literatures, it is illustrated that the persistence probability has a universal scaling form $P(t) \\sim t^{-\\theta_{p}}$ \\cite{Zheng1}. In this work, we analyzed persistence properties of universal scaling behavior on Taiwan financial market, and also calculated the global persistence exponent $\\theta_{p}$. We found our analytical results in good agreement with the same universality.

  8. The dynamic of information-driven coordination phenomena: a transfer entropy analysis

    CERN Document Server

    Borge-Holthoefer, Javier; Gonçalves, Bruno; González-Bailón, Sandra; Arenas, Alex; Moreno, Yamir; Vespignani, Alessandro

    2015-01-01

    Data from social media are providing unprecedented opportunities to investigate the processes that rule the dynamics of collective social phenomena. Here, we consider an information theoretical approach to define and measure the temporal and structural signatures typical of collective social events as they arise and gain prominence. We use the symbolic transfer entropy analysis of micro-blogging time series to extract directed networks of influence among geolocalized sub-units in social systems. This methodology captures the emergence of system-level dynamics close to the onset of socially relevant collective phenomena. The framework is validated against a detailed empirical analysis of five case studies. In particular, we identify a change in the characteristic time-scale of the information transfer that flags the onset of information-driven collective phenomena. Furthermore, our approach identifies an order-disorder transition in the directed network of influence between social sub-units. In the absence of ...

  9. Dynamic self-organization phenomena in complex ionized gas systems: new paradigms and technological aspects

    Science.gov (United States)

    Vladimirov, S. V.; Ostrikov, K.

    2004-04-01

    An overview of dynamic self-organization phenomena in complex ionized gas systems, associated physical phenomena, and industrial applications is presented. The most recent experimental, theoretical, and modeling efforts to understand the growth mechanisms and dynamics of nano- and micron-sized particles, as well as the unique properties of the plasma-particle systems (colloidal, or complex plasmas) and the associated physical phenomena are reviewed and the major technological applications of micro- and nanoparticles are discussed. Until recently, such particles were considered mostly as a potential hazard for the microelectronic manufacturing and significant efforts were applied to remove them from the processing volume or suppress the gas-phase coagulation. Nowadays, fine clusters and particulates find numerous challenging applications in fundamental science as well as in nanotechnology and other leading high-tech industries.

  10. Critical phenomena and noise-induced phase transitions in neuronal networks.

    Science.gov (United States)

    Lee, K-E; Lopes, M A; Mendes, J F F; Goltsev, A V

    2014-01-01

    We study numerically and analytically first- and second-order phase transitions in neuronal networks stimulated by shot noise (a flow of random spikes bombarding neurons). Using an exactly solvable cortical model of neuronal networks on classical random networks, we find critical phenomena accompanying the transitions and their dependence on the shot noise intensity. We show that a pattern of spontaneous neuronal activity near a critical point of a phase transition is a characteristic property that can be used to identify the bifurcation mechanism of the transition. We demonstrate that bursts and avalanches are precursors of a first-order phase transition, paroxysmal-like spikes of activity precede a second-order phase transition caused by a saddle-node bifurcation, while irregular spindle oscillations represent spontaneous activity near a second-order phase transition caused by a supercritical Hopf bifurcation. Our most interesting result is the observation of the paroxysmal-like spikes. We show that a paroxysmal-like spike is a single nonlinear event that appears instantly from a low background activity with a rapid onset, reaches a large amplitude, and ends up with an abrupt return to lower activity. These spikes are similar to single paroxysmal spikes and sharp waves observed in electroencephalographic (EEG) measurements. Our analysis shows that above the saddle-node bifurcation, sustained network oscillations appear with a large amplitude but a small frequency in contrast to network oscillations near the Hopf bifurcation that have a small amplitude but a large frequency. We discuss an amazing similarity between excitability of the cortical model stimulated by shot noise and excitability of the Morris-Lecar neuron stimulated by an applied current.

  11. Complex Phenomena Understanding in Electricity through Dynamically Linked Concrete and Abstract Representations

    Science.gov (United States)

    Taramopoulos, A.; Psillos, D.

    2017-01-01

    The present study investigates the impact of utilizing virtual laboratory environments combining dynamically linked concrete and abstract representations in investigative activities on the ability of students to comprehend simple and complex phenomena in the field of electric circuits. Forty-two 16- to 17-year-old high school students participated…

  12. Phase Locking Phenomena and Electroencephalogram-Like Activities in Dynamic Neuronal Systems

    Institute of Scientific and Technical Information of China (English)

    XU Xin-Jian; WANG Sheng-Jun; TANG Wei; WANG Ying-Hai

    2005-01-01

    @@ We study signal detection and transduction of dynamic neuronal systems under the influence of external noise,white and coloured. Based on simulations, we show explicitly phase locking phenomena between the output and the input of a single neuron and Electroencephalogram-like activities on neural networks with small-world connectivity. The numerical results prove that the dynamic neuronal system can be adjusted to an optimal sensitive state for signal processing in the presence of additive noise.

  13. Liquid crystalline critical dynamics in decylammonium chloride

    CERN Document Server

    Lee, K W; Lee, C E; Kang, K H; Rhee, C; Kang, J K

    1999-01-01

    Collective chain dynamics and phase transitions in a model biomembrane, decylammonium chloride (C sub 1 sub 0 H sub 2 sub 1 NH sub 3 Cl), were studied by means of proton nuclear magnetic resonance. Our measurements sensitively reflect the critical dynamics associated with the smectic C to smectic A transition of the lipid bilayer.

  14. Stabilization and utilization of nonlinear phenomena based on bifurcation control for slow dynamics

    Science.gov (United States)

    Yabuno, Hiroshi

    2008-08-01

    Mechanical systems may experience undesirable and unexpected behavior and instability due to the effects of nonlinearity of the systems. Many kinds of control methods to decrease or eliminate the effects have been studied. In particular, bifurcation control to stabilize or utilize nonlinear phenomena is currently an active topic in the field of nonlinear dynamics. This article presents some types of bifurcation control methods with the aim of realizing vibration control and motion control for mechanical systems. It is also indicated through every control method that slowly varying components in the dynamics play important roles for the control and the utilizations of nonlinear phenomena. In the first part, we deal with stabilization control methods for nonlinear resonance which is the 1/3-order subharmonic resonance in a nonlinear spring-mass-damper system and the self-excited oscillation (hunting motion) in a railway vehicle wheelset. The second part deals with positive utilizations of nonlinear phenomena by the generation and the modification of bifurcation phenomena. We propose the amplitude control method of the cantilever probe of an atomic force microscope (AFM) by increasing the nonlinearity in the system. Also, the motion control of a two link underactuated manipulator with a free link and an active link is considered by actuating the bifurcations produced under high-frequency excitation. This article is a discussion on the bifurcation control methods presented by the author and co-researchers by focusing on the actuation of the slowly varying components included in the original dynamics.

  15. Critical behavior of a dynamical percolation model

    Institute of Scientific and Technical Information of China (English)

    YU Mei-Ling; XU Ming-Mei; LIU Zheng-You; LIU Lian-Shou

    2009-01-01

    The critical behavior of the dynamical percolation model, which realizes the molecular-aggregation conception and describes the crossover between the hadronic phase and the partonic phase, is studied in detail. The critical percolation distance for this model is obtained by using the probability P∞ of the appearance of an infinite cluster. Utilizing the finite-size scaling method the critical exponents γ/v and T are extracted from the distribution of the average cluster size and cluster number density. The influences of two model related factors, I.e. The maximum bond number and the definition of the infinite cluster, on the critical behavior are found to be small.

  16. Mechanical impact of dynamic phenomena in Francis turbines at off design conditions

    Science.gov (United States)

    Duparchy, F.; Brammer, J.; Thibaud, M.; Favrel, A.; Lowys, P. Y.; Avellan, F.

    2017-04-01

    At partial load and overload conditions, Francis turbines are subjected to hydraulic instabilities that can potentially result in high dynamic solicitations of the turbine components and significantly reduce their lifetime. This study presents both experimental data and numerical simulations that were used as complementary approaches to study these dynamic solicitations. Measurements performed on a reduced scale physical model, including a special runner instrumented with on-board strain gauges and pressure sensors, were used to investigate the dynamic phenomena experienced by the runner. They were also taken as reference to validate the numerical simulation results. After validation, advantage was taken from the numerical simulations to highlight the mechanical response of the structure to the unsteady hydraulic phenomena, as well as their impact on the fatigue damage of the runner.

  17. Dissipative particle dynamics simulation of wettability alternation phenomena in the chemical flooding process

    Institute of Scientific and Technical Information of China (English)

    Xiaobo Li; Yuewu Liu; Jianfei Tang; Shujiao Li

    2009-01-01

    Wettability alternation phenomena is considered one of the most important enhanced oil recovery (EOR) mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics (DPD). Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to waterwet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.

  18. Symmetry in Critical Random Boolean Networks Dynamics

    Science.gov (United States)

    Bassler, Kevin E.; Hossein, Shabnam

    2014-03-01

    Using Boolean networks as prototypical examples, the role of symmetry in the dynamics of heterogeneous complex systems is explored. We show that symmetry of the dynamics, especially in critical states, is a controlling feature that can be used to both greatly simplify analysis and to characterize different types of dynamics. Symmetry in Boolean networks is found by determining the frequency at which the various Boolean output functions occur. Classes of functions occur at the same frequency. These classes are orbits of the controlling symmetry group. We find the nature of the symmetry that controls the dynamics of critical random Boolean networks by determining the frequency of output functions utilized by nodes that remain active on dynamical attractors. This symmetry preserves canalization, a form of network robustness. We compare it to a different symmetry known to control the dynamics of an evolutionary process that allows Boolean networks to organize into a critical state. Our results demonstrate the usefulness and power of using symmetry to characterize complex network dynamics, and introduce a novel approach to the analysis of heterogeneous complex systems. This work was supported by the NSF through grants DMR-0908286 and DMR-1206839, and by the AFSOR and DARPA through grant FA9550-12-1-0405.

  19. Epigenetic phenomena, chromatin dynamics, and gene expression. New theoretical approaches in the study of living systems.

    Science.gov (United States)

    Boi, Luciano

    2008-01-01

    This paper is aimed at exploring the genome at the level beyond that of DNA sequence alone. We stress the fact that the level of genes is not the sole "reality" in the living world, for there are different epigenetic processes that profoundly affect change in living systems. Moreover, epigenetics very likely influences the course of evolution and the unfolding of life. We further attempt to investigate how the genome is dynamically organized into the nuclear space within the cell. We mainly focus on analyses of higher order nuclear architecture and the dynamic interactions of chromatin with other nuclear components. We especially want to know how epigenetic phenomena influences genes expression and chromosome functions. The proper understanding of these processes require new concepts and approaches be introduced and developed. In particular, we think that research in biology has to shift from only describing molecular and local features of living systems to studying the regulatory networks of interactions among gene pathways, the folding and dynamics of chromatin structure and how environmental factors affects the behavior of organisms. There are essential components of biological information on living organisms which cannot be portrayed in the DNA sequence alone. In a post-genomic era, the importance of chromatin/epigenetic interface has become increasingly apparent. One of the purposes of current research should be to highlight the enormous impact of chromatin organization and dynamics on epigenetic phenomena, and, conversely, to emphasize the important role that epigenetic phenomena play in gene expression and cell regulation.

  20. Critical phenomena at a first-order phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity

    Science.gov (United States)

    Minati, Ludovico; de Candia, Antonio; Scarpetta, Silvia

    2016-07-01

    Networks of non-linear electronic oscillators have shown potential as physical models of neural dynamics. However, two properties of brain activity, namely, criticality and metastability, remain under-investigated with this approach. Here, we present a simple circuit that exhibits both phenomena. The apparatus consists of a two-dimensional square lattice of capacitively coupled glow (neon) lamps. The dynamics of lamp breakdown (flash) events are controlled by a DC voltage globally connected to all nodes via fixed resistors. Depending on this parameter, two phases having distinct event rate and degree of spatiotemporal order are observed. The transition between them is hysteretic, thus a first-order one, and it is possible to enter a metastability region, wherein, approaching a spinodal point, critical phenomena emerge. Avalanches of events occur according to power-law distributions having exponents ≈3/2 for size and ≈2 for duration, and fractal structure is evident as power-law scaling of the Fano factor. These critical exponents overlap observations in biological neural networks; hence, this circuit may have value as building block to realize corresponding physical models.

  1. The dynamics of information-driven coordination phenomena: A transfer entropy analysis.

    Science.gov (United States)

    Borge-Holthoefer, Javier; Perra, Nicola; Gonçalves, Bruno; González-Bailón, Sandra; Arenas, Alex; Moreno, Yamir; Vespignani, Alessandro

    2016-04-01

    Data from social media provide unprecedented opportunities to investigate the processes that govern the dynamics of collective social phenomena. We consider an information theoretical approach to define and measure the temporal and structural signatures typical of collective social events as they arise and gain prominence. We use the symbolic transfer entropy analysis of microblogging time series to extract directed networks of influence among geolocalized subunits in social systems. This methodology captures the emergence of system-level dynamics close to the onset of socially relevant collective phenomena. The framework is validated against a detailed empirical analysis of five case studies. In particular, we identify a change in the characteristic time scale of the information transfer that flags the onset of information-driven collective phenomena. Furthermore, our approach identifies an order-disorder transition in the directed network of influence between social subunits. In the absence of clear exogenous driving, social collective phenomena can be represented as endogenously driven structural transitions of the information transfer network. This study provides results that can help define models and predictive algorithms for the analysis of societal events based on open source data.

  2. Critical dynamics of burst instabilities in the Portevin-Le Ch atelier effect.

    Science.gov (United States)

    D'Anna, G; Nori, F

    2000-11-06

    We investigate the Portevin-Le Châtelier effect (PLC), by compressing Al-Mg alloys in a very large deformation range, and interpret the results from the viewpoint of phase transitions and critical phenomena. The system undergoes two dynamical phase transitions between intermittent (or "jerky") and "laminar" plastic dynamic phases. Near these two dynamic critical points, the order parameter 1/tau of the PLC effect exhibits large fluctuations, and "critical slowing down" (i.e., the number tau of bursts, or plastic instabilities, per unit time slows down considerably).

  3. On certain peculiarities of the division of methane during gas dynamic phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Nechaev, A.V.

    1981-01-01

    Statistical data on the separation of methane during sudden eruptions and other gas dynamic phenomena in the mines of the Donets basin are analyzed. It is established, that the largest values of relative methane separation are characteristic for eruptions of coal, which are caused by explosive works. Graphs of the changes of the concentration of methane during different types of gas dynamic phenomena are introduced and their peculiarities are noted. Materials on gas separation during sudden eruptions in basic coal basins are generalized. It is shown that in Donbas, as in other basins, the value of relative gas separation changes within wide limits and in a series of cases significantly raised the natural gas bearing capability of coal layers.

  4. Symmetry in critical random Boolean network dynamics

    Science.gov (United States)

    Hossein, Shabnam; Reichl, Matthew D.; Bassler, Kevin E.

    2014-04-01

    Using Boolean networks as prototypical examples, the role of symmetry in the dynamics of heterogeneous complex systems is explored. We show that symmetry of the dynamics, especially in critical states, is a controlling feature that can be used both to greatly simplify analysis and to characterize different types of dynamics. Symmetry in Boolean networks is found by determining the frequency at which the various Boolean output functions occur. There are classes of functions that consist of Boolean functions that behave similarly. These classes are orbits of the controlling symmetry group. We find that the symmetry that controls the critical random Boolean networks is expressed through the frequency by which output functions are utilized by nodes that remain active on dynamical attractors. This symmetry preserves canalization, a form of network robustness. We compare it to a different symmetry known to control the dynamics of an evolutionary process that allows Boolean networks to organize into a critical state. Our results demonstrate the usefulness and power of using the symmetry of the behavior of the nodes to characterize complex network dynamics, and introduce an alternative approach to the analysis of heterogeneous complex systems.

  5. Symmetry in critical random Boolean network dynamics.

    Science.gov (United States)

    Hossein, Shabnam; Reichl, Matthew D; Bassler, Kevin E

    2014-04-01

    Using Boolean networks as prototypical examples, the role of symmetry in the dynamics of heterogeneous complex systems is explored. We show that symmetry of the dynamics, especially in critical states, is a controlling feature that can be used both to greatly simplify analysis and to characterize different types of dynamics. Symmetry in Boolean networks is found by determining the frequency at which the various Boolean output functions occur. There are classes of functions that consist of Boolean functions that behave similarly. These classes are orbits of the controlling symmetry group. We find that the symmetry that controls the critical random Boolean networks is expressed through the frequency by which output functions are utilized by nodes that remain active on dynamical attractors. This symmetry preserves canalization, a form of network robustness. We compare it to a different symmetry known to control the dynamics of an evolutionary process that allows Boolean networks to organize into a critical state. Our results demonstrate the usefulness and power of using the symmetry of the behavior of the nodes to characterize complex network dynamics, and introduce an alternative approach to the analysis of heterogeneous complex systems.

  6. Global and Local Approaches Describing Critical Phenomena on the Developing and Developed Financial Markets

    Science.gov (United States)

    Grech, Dariusz

    We define and confront global and local methods to analyze the financial crash-like events on the financial markets from the critical phenomena point of view. These methods are based respectively on the analysis of log-periodicity and on the local fractal properties of financial time series in the vicinity of phase transitions (crashes). The log-periodicity analysis is made in a daily time horizon, for the whole history (1991-2008) of Warsaw Stock Exchange Index (WIG) connected with the largest developing financial market in Europe. We find that crash-like events on the Polish financial market are described better by the log-divergent price model decorated with log-periodic behavior than by the power-law-divergent price model usually discussed in log-periodic scenarios for developed markets. Predictions coming from log-periodicity scenario are verified for all main crashes that took place in WIG history. It is argued that crash predictions within log-periodicity model strongly depend on the amount of data taken to make a fit and therefore are likely to contain huge inaccuracies. Next, this global analysis is confronted with the local fractal description. To do so, we provide calculation of the so-called local (time dependent) Hurst exponent H loc for the WIG time series and for main US stock market indices like DJIA and S&P 500. We point out dependence between the behavior of the local fractal properties of financial time series and the crashes appearance on the financial markets. We conclude that local fractal method seems to work better than the global approach - both for developing and developed markets. The very recent situation on the market, particularly related to the Fed intervention in September 2007 and the situation immediately afterwards is also analyzed within fractal approach. It is shown in this context how the financial market evolves through different phases of fractional Brownian motion. Finally, the current situation on American market is

  7. PREFACE: Dynamically slow processes and near-arrest phenomena in soft matter Dynamically slow processes and near-arrest phenomena in soft matter

    Science.gov (United States)

    Chen, Sow-Hsin

    2009-12-01

    The aim of this special issue is to summarize what has been learnt by both the network (the Marie Curie Research and Training Network on Arrested Matter) and the broader international community on dynamically slow processes and near-arrest phenomena. Another aspect of this special issue is to highlight new directions in which dynamical slowing down is, or may be, important. In particular, this issue is dedicated to a member of this network, Professor Francesco Mallamace, who reached the venerable age of 60 in 2008. Professor Francesco Mallamace is one of the group leaders of the complex materials and systems worldwide network. In particular he is a pioneer who has successfully investigated aggregation phenomena and the dynamics of colloids, and the properties of water in the deeply supercooled phase region. The scientific activities of Professor Mallamace are mainly experimental, making use of different scattering and spectroscopic techniques. He is a very active and well-known scientist not only for his research but also for training young scientists by organizing many international networks, congresses and schools. Under his influence, mainly by taking advantage of large international collaborative activities, the University of Messina has become one of the major European centers for complex systems. Among the invited speakers to the final conference of the network, we have collected the following 11 interesting articles. In this special issue, we roughly classify the papers according to three major groups: the first four papers deal with the theory and experiments on the dynamic crossover phenomena in general glass-forming liquids, the next four papers deal explicitly with slow dynamics in supercooled confined water and the last three papers deal with the interpretation of the near-arrest phenomena in colloids. Chong et al used an extended mode coupling theory, which includes the hopping effect, to predict a dynamic crossover at Tc in the α-relaxation time and

  8. Applications of Canonical transformations and nontrivial vacuum solutions to flavor mixing and critical phenomena in quantum field theory

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, Yuriy [North Carolina State Univ., Raleigh, NC (United States)

    2004-12-01

    MISHCHENKO, YURIY. Applications of Canonical Transformations and Nontrivial Vacuum Solutions to flavor mixing and critical phenomena in Quantum Field Theory. (Under the direction of Chueng-Ryong Ji.) In this dissertation we consider two recent applications of Bogoliubov Transformation to the phenomenology of quantum mixing and the theory of critical phenomena. In recent years quantum mixing got in the focus of the searches for New Physics due to its unparalleled sensitivity to SM parameters and indications of neutrino mixing. It was recently suggested that Bogoliubov Transformation may be important in proper definition of the flavor states that otherwise results in problems in perturbative treatment. As first part of this dissertation we investigate this conjecture and develop a complete formulation of such a mixing field theory involving introduction of general formalism, analysis of space-time conversion and phenomenological implications. As second part of this dissertati

  9. Pre-X Experimental Re-Entry Lifting Body: Design of Flight Test Experiments for Critical Aerothermal Phenomena

    Science.gov (United States)

    2007-06-01

    hypersonic domain has never been explored with a controlled glider . BOR 4 BOR 5 The hypersonic glider HYFLEX The main concrete...the most critical phenomena concerning the design and sizing of a re- entry vehicle. Pre-X hypersonic glider • Improving the flight measurement...laws of a gliding body with body flaps. • Performing the first design and development end to end of the hypersonic glider . • To reduce risk for

  10. Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics

    Institute of Scientific and Technical Information of China (English)

    XU; Mingyu; TAN; Wenchang

    2006-01-01

    From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional calculus and fractional differential equations) used for describing intermediate processes and critical phenomena in physics and mechanics, their progress in theory and methods and their applications to modern mechanics. Some authors' researches in this area in recent years are included. Finally, prospects and evaluation for this subject are made.

  11. Fractional generalization of the Ginzburg–Landau equation: an unconventional approach to critical phenomena in complex media

    DEFF Research Database (Denmark)

    Milovanov, A.V.; Juul Rasmussen, J.

    2005-01-01

    class of critical phenomena when the organization of the system near the phase transition point is influenced by a competing nonlocal ordering. Fractional modifications of the free energy functional at criticality and of the widely known Ginzburg-Landau equation central to the classical Landau theory...... of second-type phase transitions are discussed in some detail. An implication of the fractional Ginzburg-Landau equation is a renormalization of the transition temperature owing to the nonlocality present. (c) 2005 Elsevier B.V. All rights reserved....

  12. [Psychopathological phenomena and personality disorders (the issue of dynamic aspects of psychopathologies)].

    Science.gov (United States)

    Smulevich, A B

    2000-01-01

    An analysis of the interaction between pathocharacterological and psychopathological (affective, anxious-phobic and hysterical) phenomena within "borderline psychiatry" (reactions, phases, development) gives evidence to the existence of 2 clinically heterogeneous variations of comorbid interactions. The first variation: primary psychopathological syndromes manifesting without any significant correlation with personality disorders and transform into pathocharacterological ones (neurotic, postreactive) personality development by means of "amalgamating" mechanism. The second variation: secondary (in regard to personality disorders) psychopathological phenomena forming on the basis of constitutional personality traits by means of "splitting off" mechanism and are defined as personality disorders with predisposition to manifest positive psychopathological symptomatology. Formation of isolated obsessive and dissociative disorders within the structure of "basic" pathocharacterological phenomena (variation 2) predicts a future absence of growing severity of personality disorders (i.e. a dynamics traditionally defined as the development--variation 1) and stabilization of psychopathic traits with features of compensation of the latter. The possibilities of pathological dynamics in psychopathic personality with a "splitting off" of the isolated psychopathological syndromes exhausted; for decades neither growing severity of personality disorders, nor an exacerbation of those psychopathological complexes which provided a primary base for manifestation of positive symptomatology may be observed.

  13. Collective phenomena in crowds-Where pedestrian dynamics need social psychology.

    Science.gov (United States)

    Sieben, Anna; Schumann, Jette; Seyfried, Armin

    2017-01-01

    This article is on collective phenomena in pedestrian dynamics during the assembling and dispersal of gatherings. To date pedestrian dynamics have been primarily studied in the natural and engineering sciences. Pedestrians are analyzed and modeled as driven particles revealing self-organizing phenomena and complex transport characteristics. However, pedestrians in crowds also behave as living beings according to stimulus-response mechanisms or act as human subjects on the basis of social norms, social identities or strategies. To show where pedestrian dynamics need social psychology in addition to the natural sciences we propose the application of three categories-phenomena, behavior and action. They permit a clear discrimination between situations in which minimal models from the natural sciences are appropriate and those in which sociological and psychological concepts are needed. To demonstrate the necessity of this framework, an experiment in which a large group of people (n = 270) enters a concert hall through two different spatial barrier structures is analyzed. These two structures correspond to everyday situations such as boarding trains and access to immigration desks. Methods from the natural and social sciences are applied. Firstly, physical measurements show the influence of the spatial structure on the dynamics of the entrance procedure. Density, waiting time and speed of progress show large variations. Secondly, a questionnaire study (n = 60) reveals how people perceive and evaluate these entrance situations. Markedly different expectations, social norms and strategies are associated with the two spatial structures. The results from the questionnaire study do not always conform to objective physical measures, indicating the limitations of models which are based on objective physical measures alone and which neglect subjective perspectives.

  14. Numerical Simulations on Nonlinear Dynamics in Lasers as Related High Energy Physics Phenomena

    Directory of Open Access Journals (Sweden)

    Andreea Rodica Sterian

    2013-01-01

    Full Text Available This paper aims to present some results on nonlinear dynamics in active nanostructures as lasers with quantum wells and erbium doped laser systems using mathematical models, methods, and numerical simulations for some related high energy physics phenomena. We discuss nonlinear dynamics of laser with quantum wells and of fiber optics laser and soliton interactions. The results presented have important implications in particle detection and postdetection processing of information as well as in soliton generation and amplification or in the case that these simulations are thought to be useful in the experiments concerning the high energy particles. The soliton behaviour as particle offers the possibility to use solitons for better understanding of real particles in this field. The developed numerical models concerning nonlinear dynamics in nanostructured lasers, erbium doped laser systems, the soliton interactions, and the obtained results are consistent with the existing data in the literature.

  15. A Detailed Study of the Rotational Augmentation and Dynamic Stall Phenomena for Wind Turbines

    DEFF Research Database (Denmark)

    Guntur, Srinivas

    ), using rotationally augmented steady state polars as the input instead of the typically used 2D (stationary) data. The aim of this part of the work has been to investigate the differences between the stall phenomenon on harmonically pitching blades on a rotating wind turbine and the classic dynamic stall......This thesis presents investigations into the aerodynamics of wind turbine rotors, with a focus on the in-board sections of the rotor. Two important aerodynamic phenomena that have challenged scientists over nearly the last half a century are the so-called rotational augmentation and dynamic stall...... on wind turbine blades using the N-sequence data of the NREL UAE Phase VI experiment. The experimental data is compared with the results from unsteady Delayed Detached Eddy Simulations (DDES). The same conditions are also modelled using a Beddoes-Leishman type dynamic stall model by Hansen et al. (2004...

  16. On the critical phenomena and thermodynamic geometry of charged Gauss-Bonnet AdS black hole

    CERN Document Server

    Wei, Shao-Wen

    2012-01-01

    In this paper, we study the phase structure and equilibrium state space geometry of charged topological Gauss-Bonnet black holes in $d$-dimensional anti-de Sitter spacetime. Serval critical points are obtained in the canonical ensemble, and the critical phenomena and critical exponents near them are examined. We find that the phase structures and critical phenomena drastically depend on the cosmological constant $\\Lambda$ and dimensionality $d$. The result also shows that there exists an analogy between the black hole and the van der Waals liquid gas system. Moreover, we explore the phase transition and possible property of the microstructure using the state space geometry. It is found that the Ruppeiner curvature diverges exactly at the points where the heat capacity at constant charge of the black hole diverges. This black hole is also found to be a multiple system, i.e., it is similar to the ideal gas of fermions in some range of the parameters, while to the ideal gas of bosons in another range.

  17. Dynamic universality class of the QCD critical point

    OpenAIRE

    Son, D. T.; Stephanov, M. A.

    2004-01-01

    We show that the dynamic universality class of the QCD critical point is that of model H and discuss the dynamic critical exponents. We show that the baryon diffusion rate vanishes at the critical point. The dynamic critical index $z$ is close to 3.

  18. Critical phenomena in the majority voter model on two-dimensional regular lattices.

    Science.gov (United States)

    Acuña-Lara, Ana L; Sastre, Francisco; Vargas-Arriola, José Raúl

    2014-05-01

    In this work we studied the critical behavior of the critical point as a function of the number of nearest neighbors on two-dimensional regular lattices. We performed numerical simulations on triangular, hexagonal, and bilayer square lattices. Using standard finite-size scaling theory we found that all cases fall in the two-dimensional Ising model universality class, but that the critical point value for the bilayer lattice does not follow the regular tendency that the Ising model shows.

  19. Mill and Mental Phenomena: Critical Contributions to a Science of Cognition

    Directory of Open Access Journals (Sweden)

    Steven L. Bistricky

    2013-04-01

    Full Text Available Attempts to define cognition preceded John Stuart Mill’s life and continue to this day. John Stuart Mill envisioned a science of mental phenomena informed by associationism, empirical introspection, and neurophysiology, and he advanced specific ideas that still influence modern conceptions of cognition. The present article briefly reviews Mill’s personal history and the times in which he lived, and it traces the evolution of ideas that have run through him to contemporary cognitive concepts. The article also highlights contemporary problems in defining cognition and supports specific criteria regarding what constitutes cognition.

  20. Mill and mental phenomena: critical contributions to a science of cognition.

    Science.gov (United States)

    Bistricky, Steven L

    2013-06-01

    Attempts to define cognition preceded John Stuart Mill's life and continue to this day. John Stuart Mill envisioned a science of mental phenomena informed by associationism, empirical introspection, and neurophysiology, and he advanced specific ideas that still influence modern conceptions of cognition. The present article briefly reviews Mill's personal history and the times in which he lived, and it traces the evolution of ideas that have run through him to contemporary cognitive concepts. The article also highlights contemporary problems in defining cognition and supports specific criteria regarding what constitutes cognition.

  1. Evaluation of equations of state for simultaneous representation of phase equilibrium and critical phenomena

    DEFF Research Database (Denmark)

    Pinto Coelho Muniz Vinhal, Andre; Yan, Wei; Kontogeorgis, Georgios

    2017-01-01

    Precise description of the critical points with association equations of state requires rescaling of the parameters to match experimental critical temperature and pressure of pure components. In this work we developed a method to include critical data restrictions in the parametrization procedure...... of the Cubic-Plus-Association (CPA) equation of state (EoS). We obtained new parameters for methanol and alkanes from n-hexane to n-decane. The comparison with the original parameters showed that this procedure is important for associating compounds, since for inert species the equation reduces to the Soave...

  2. A framework towards understanding mesoscopic phenomena: Emergent unpredictability, symmetry breaking and dynamics across scales

    Science.gov (United States)

    Qian, Hong; Ao, Ping; Tu, Yuhai; Wang, Jin

    2016-11-01

    By integrating four lines of thoughts: symmetry breaking originally advanced by Anderson, bifurcation from nonlinear dynamical systems, Landau's phenomenological theory of phase transition, and the mechanism of emergent rare events first studied by Kramers, we introduce a possible framework for understanding mesoscopic dynamics that links (i) fast microscopic (lower level) motions, (ii) movements within each basin-of-attraction at the mid-level, and (iii) higher-level rare transitions between neighboring basins, which have slow rates that decrease exponentially with the size of the system. In this mesoscopic framework, the fast dynamics is represented by a rapidly varying stochastic process and the mid-level by a nonlinear dynamics. Multiple attractors arise as emergent properties of the nonlinear systems. The interplay between the stochastic element and nonlinearity, the essence of Kramers' theory, leads to successive jump-like transitions among different basins. We argue each transition is a dynamic symmetry breaking, with the potential of exhibiting Thom-Zeeman catastrophe as well as phase transition with the breakdown of ergodicity (e.g., cell differentiation). The slow-time dynamics of the nonlinear mesoscopic system is not deterministic, rather it is a discrete stochastic jump process. The existence of these discrete states and the Markov transitions among them are both emergent phenomena. This emergent stochastic jump dynamics then serves as the stochastic element for the nonlinear dynamics of a higher level aggregates on an even larger spatial and slower time scales (e.g., evolution). This description captures the hierarchical structure outlined by Anderson and illustrates two distinct types of limit of a mesoscopic dynamics: A long-time ensemble thermodynamics in terms of time t → ∞ followed by the size of the system N → ∞ , and a short-time trajectory steady state with N → ∞ followed by t → ∞ . With these limits, symmetry breaking and cusp

  3. Reaction kinetics and critical phenomena: iodination of acetone in isobutyric acid + water near the consolute point.

    Science.gov (United States)

    Hu, Baichuan; Baird, James K

    2010-01-14

    The rate of iodination of acetone has been measured as a function of temperature in the binary solvent isobutyric acid (IBA) + water near the upper consolute point. The reaction mixture was prepared by the addition of acetone, iodine, and potassium iodide to IBA + water at its critical composition of 38.8 mass % IBA. The value of the critical temperature determined immediately after mixing was 25.43 degrees C. Aliquots were extracted from the mixture at regular intervals in order to follow the time course of the reaction. After dilution of the aliquot with water to quench the reaction, the concentration of triiodide ion was determined by the measurement of the optical density at a wavelength of 565 nm. These measurements showed that the kinetics were zeroth order. When at the end of 24 h the reaction had come to equilibrium, the critical temperature was determined again and found to be 24.83 degrees C. An Arrhenius plot of the temperature dependence of the observed rate constant, k(obs), was linear over the temperature range 27.00-38.00 degrees C, but between 25.43 and 27.00 degrees C, the values of k(obs) fell below the extrapolation of the Arrhenius line. This behavior is evidence in support of critical slowing down. Our experimental method and results are significant in three ways: (1) In contrast to in situ measurements of optical density, the determination of the optical density of diluted aliquots avoided any interference from critical opalescence. (2) The measured reaction rate exhibited critical slowing down. (3) The rate law was pseudo zeroth order both inside and outside the critical region, indicating that the reaction mechanism was unaffected by the presence of the critical point.

  4. Natural time analysis of critical phenomena: The case of pre-fracture electromagnetic emissions

    Energy Technology Data Exchange (ETDEWEB)

    Potirakis, S. M. [Department of Electronics, Technological Education Institute (TEI) of Piraeus, 250 Thivon and P. Ralli, Aigaleo, Athens GR-12244 (Greece); Karadimitrakis, A. [Department of Physics, Section of Electronics, Computers, Telecommunications and Control, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece); Eftaxias, K. [Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece)

    2013-06-15

    Criticality of complex systems reveals itself in various ways. One way to monitor a system at critical state is to analyze its observable manifestations using the recently introduced method of natural time. Pre-fracture electromagnetic (EM) emissions, in agreement to laboratory experiments, have been consistently detected in the MHz band prior to significant earthquakes. It has been proposed that these emissions stem from the fracture of the heterogeneous materials surrounding the strong entities (asperities) distributed along the fault, preventing the relative slipping. It has also been proposed that the fracture of heterogeneous material could be described in analogy to the critical phase transitions in statistical physics. In this work, the natural time analysis is for the first time applied to the pre-fracture MHz EM signals revealing their critical nature. Seismicity and pre-fracture EM emissions should be two sides of the same coin concerning the earthquake generation process. Therefore, we also examine the corresponding foreshock seismic activity, as another manifestation of the same complex system at critical state. We conclude that the foreshock seismicity data present criticality features as well.

  5. Continuum theory of critical phenomena in polymer solutions: Formalism and mean field approximation

    Science.gov (United States)

    Goldstein, Raymond E.; Cherayil, Binny J.

    1989-06-01

    A theoretical description of the critical point of a polymer solution is formulated directly from the Edwards continuum model of polymers with two- and three-body excluded-volume interactions. A Hubbard-Stratonovich transformation analogous to that used in recent work on the liquid-vapor critical point of simple fluids is used to recast the grand partition function of the polymer solution as a functional integral over continuous fields. The resulting Landau-Ginzburg-Wilson (LGW) Hamiltonian is of the form of a generalized nonsymmetric n=1 component vector model, with operators directly related to certain connected correlation functions of a reference system. The latter is taken to be an ensemble of Gaussian chains with three-body excluded-volume repulsions, and the operators are computed in three dimensions by means of a perturbation theory that is rapidly convergent for long chains. A mean field theory of the functional integral yields a description of the critical point in which the power-law variations of the critical polymer volume fraction φc, critical temperature Tc, and critical amplitudes on polymerization index N are essentially identical to those found in the Flory-Huggins theory. In particular, we find φc ˜N-1/2, Tθ-Tc˜N-1/2 with (Tθ the theta temperature), and that the composition difference between coexisting phases varies with reduced temperature t as N-1/4t1/2. The mean field theory of the interfacial tension σ between coexisting phases near the critical point, developed by considering the LGW Hamiltonian for a weakly inhomogeneous solution, yields σ˜N-1/4t3/2, with the correlation length diverging as ξ˜N1/4t-1/2 within the same approximation, consistent with the mean field limit of de Gennes' scaling form. Generalizations to polydisperse systems are discussed.

  6. Dynamical response near quantum critical points

    CERN Document Server

    Lucas, Andrew; Podolsky, Daniel; Witczak-Krempa, William

    2016-01-01

    We study high frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from conformal field theory allow us to fix the high frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O(N) model and using the gauge-gravity duality, and numerically via Quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons qualitatively change the high frequency optical conductivity, and the corresponding sum rule.

  7. Dynamical Response near Quantum Critical Points

    Science.gov (United States)

    Lucas, Andrew; Gazit, Snir; Podolsky, Daniel; Witczak-Krempa, William

    2017-02-01

    We study high-frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from quantum field theory allow us to fix the high-frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O (N ) model and using the gauge-gravity duality and numerically via quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons qualitatively change the high-frequency optical conductivity and the corresponding sum rule.

  8. Static critical phenomena in Co-Ni-Ga ferromagnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sethi, Brahmananda, E-mail: santra@iitg.ernet.in; Sarma, S., E-mail: santra@iitg.ernet.in; Srinivasan, A., E-mail: santra@iitg.ernet.in; Santra, S. B., E-mail: santra@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039 (India)

    2014-04-24

    Ferromagnetic shape memory alloys are smart materials because they exhibit temperature driven shape memory effect and magnetic field induced strain. Thus two types of energy, i.e. thermal and magnetic, are used to control their shape memory behaviour. Study of critical phenomenon in such materials has received increased experimental and theoretical attention for better understanding of the magnetic phase transition behavior as well as further development of ferromagnetic shape memory materials. In the present study we report the preparation and characterization of bulk Co{sub 45}Ni{sub 25}Ga{sub 30} alloy, prepared by a sequence of arc melting technique followed by homogenization at 1150 °C for 24 hours and ice-water quenching. Structural and magnetic properties of the alloys were studied by means of X-ray diffraction and vibrating sample magnetometer in an applied field range of ±18 kOe equipped with a high temperature oven. We have determined the critical temperature T{sub C} (∼375.5 K) and the critical exponents viz; β=0.40, γ=1.68 and δ=5.2. Asymptotic critical exponents β, γ, and δ obey Widom scaling relation, γ+β=βδ, and the magnetization data satisfy the scaling equation of state for second-order phase transition in the asymptotic critical region.

  9. The Critical Phenomena and Thermodynamics of the Reissner-Nordstrom-de Sitter Black Hole

    Directory of Open Access Journals (Sweden)

    Ren Zhao

    2014-01-01

    Full Text Available It is wellknown that there are two horizons for the Reissner-Nordstrom-de Sitter spacetime, namely, the black hole horizon and the cosmological one. Both horizons can usually seem to be two independent thermodynamic systems; however, the thermodynamic quantities on both horizons satisfy the laws of black hole thermodynamics and are not independent. In this paper by considering the relations between the two horizons we give the effective thermodynamic quantities in Reissner-Nordstrom-de Sitter spacetime. The thermodynamic properties of these effective quantities are analyzed; moreover, the critical temperature, critical pressure, and critical volume are obtained. We also discussed the thermodynamic stability of Reissner-Nordstrom-de Sitter spacetime.

  10. Evolution of Edge States and Critical Phenomena in the Rashba Superconductor with Magnetization

    Science.gov (United States)

    Yamakage, Ai; Tanaka, Yukio; Nagaosa, Naoto

    2012-02-01

    We study Andreev bound states (ABS) and the resulting charge transport of a Rashba superconductor (RSC) where two-dimensional semiconductor (2DSM) heterostructures are sandwiched by spin-singlet s-wave superconductor and ferromagnet insulator. ABS becomes a chiral Majorana edge mode in the topological phase (TP). We clarify two types of quantum criticality about the topological change of ABS near a quantum critical point (QCP), whether or not ABS exists at QCP. In the former type, ABS has an energy gap and does not cross at zero energy in the nontopological phase. These complex properties can be detected by tunneling conductance between normal metal-RSC junctions.

  11. Critical phenomena of nuclear matter in the extended Zimanyi-Moszkowski model

    CERN Document Server

    Miyazaki, K

    2005-01-01

    We have studied the thermodynamics of warm nuclear matter below the saturation density in the extended Zimanyi-Moszkowski model. The EOS behaves like van der Waals one and shows the liquid-gas phase transition as the other microscopic EOSs. It predicts the critical temperature T_{C}=16.36MeV that agrees well with its empirical value. We have further calculated the phase coexistence curve and obtained the critical exponents beta=0.34 and gamma=1.22, which also agree with their universal values and empirical values derived in the recent experimental efforts.

  12. Polarization rotation associated critical phenomena in epitaxial PbTiO{sub 3} thin films near room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Wenhui, E-mail: whma@stu.edu.cn [Department of Physics, Shantou University, Shantou, Guangdong 515063 (China)

    2016-04-15

    Strain-driven and temperature-driven monoclinic-orthorhombic phase transition in epitaxial PbTiO{sub 3} exhibit similar behavior under electric field, i.e., polarization discontinuity is reduced at the first-order ferroelectric-ferroelectric transition whose latent heat vanishes at a critical point. Due to critical phenomena the energy barrier for polarization rotation significantly diminishes, and hence thermodynamic response functions tend to diverge in the induced monoclinic states. Phenomenological calculations show that dielectric and piezoelectric properties are highly tunable by in-plane strain and electric field, and large electromechanical response may occur in epitaxial PbTiO{sub 3} thin films at room temperature. Phenomenological calculations show that large electrocaloric responsivity can also be expected at room temperature by manipulating the phase transition.

  13. Polarization rotation associated critical phenomena in epitaxial PbTiO3 thin films near room temperature

    Directory of Open Access Journals (Sweden)

    Wenhui Ma

    2016-04-01

    Full Text Available Strain-driven and temperature-driven monoclinic-orthorhombic phase transition in epitaxial PbTiO3 exhibit similar behavior under electric field, i.e., polarization discontinuity is reduced at the first-order ferroelectric-ferroelectric transition whose latent heat vanishes at a critical point. Due to critical phenomena the energy barrier for polarization rotation significantly diminishes, and hence thermodynamic response functions tend to diverge in the induced monoclinic states. Phenomenological calculations show that dielectric and piezoelectric properties are highly tunable by in-plane strain and electric field, and large electromechanical response may occur in epitaxial PbTiO3 thin films at room temperature. Phenomenological calculations show that large electrocaloric responsivity can also be expected at room temperature by manipulating the phase transition.

  14. Critical phenomena employed in hydrodynamic problems A case study of Rayleigh-Benard convection

    CERN Document Server

    Assenheimer, M; Assenheimer, Michel; Steinberg, Victor

    1996-01-01

    By virtue of Rayleigh-Benard convection, we illustrate the advantages of combining a hydrodynamic pattern forming instability with a thermodynamic critical point. This has already lead to many novel unexpected observations and is further shown to possess opportunities for the study of exciting fundamental problems in nonequilibrium systems.

  15. Simulational studies of epitaxial semiconductor superlattices: Quantum dynamical phenomena in ac and dc electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Joseph [Iowa State Univ., Ames, IA (United States)

    1997-10-08

    Using high-accuracy numerical methods the author investigates the dynamics of independent electrons in both ideal and realistic superlattices subject to arbitrary ac and/or dc electric fields. For a variety of superlattice potentials, optically excited initial wave packets, and combinations of ac and dc electric fields, he numerically solves the time-dependent Schroedinger equation. In the case of ideal periodic superlattice potentials, he investigates a long list of dynamical phenomena involving multiple miniband transitions and time-dependent electric fields. These include acceleration effects associated with interminiband transitions in strong fields, Zener resonances between minibands, dynamic localization with ac fields, increased single-miniband transport with an auxiliary resonant ac field, and enhanced or suppressed interminiband probability exchange using an auxiliary ac field. For all of the cases studied, the resulting time-dependent wave function is analyzed by projecting the data onto convenient orthonormal bases. This allows a detailed comparison with approximately analytic treatments. In an effort to explain the rapid decay of experimentally measured Bloch oscillation (BO) signals the author incorporates a one-dimensional representation of interface roughness (IR) into their superlattice potential. He shows that as a result of IR, the electron dynamics can be characterized in terms of many discrete, incommensurate frequencies near the Block frequency. Chapters 2, 3, 4 and 5 have been removed from this report and will be processed separately.

  16. Binaries, cluster dynamics and population studies of stars and stellar phenomena

    CERN Document Server

    Vanbeveren, D

    2004-01-01

    The effects of binaries on population studies of stars and stellar phenomena have been investigated over the past 3 decades by many research groups. Here we will focus mainly on the work that has been done recently in Brussels and we will consider the following topics: the effect of binaries on overall galactic chemical evolutionary models and on the rates of different types of supernova, the population of point-like X-ray sources where we distinguish the standard high mass X-ray binaries and the ULXs, a UFO-scenario for the formation of WR+OB binaries in dense star systems. Finally we critically discuss the possible effect of rotation on population studies.

  17. Boiling Visualization and Critical Heat Flux Phenomena In Narrow Rectangular Gap

    Energy Technology Data Exchange (ETDEWEB)

    J. J. Kim; Y. H. Kim; S. J. Kim; S. W. Noh; K. Y. Suh; J. Rempe; F. B. Cheung; S. B. Kim

    2004-12-01

    An experimental study was performed to investifate the pool boling critical hear flux (CHF) on one-dimensional inclined rectangular channels with narrow gaps by changing the orientation of a copper test heater assembly. In a pool of saturated water at atmospheric pressure, the test parameters include the gap sizes of 1,2,5, and 10 mm, andthe surface orientation angles from the downward facing position (180 degrees) to the vertical position (90 degress) respectively.

  18. Monte Carlo tests of renormalization-group predictions for critical phenomena in Ising models

    Science.gov (United States)

    Binder, Kurt; Luijten, Erik

    2001-04-01

    A critical review is given of status and perspectives of Monte Carlo simulations that address bulk and interfacial phase transitions of ferromagnetic Ising models. First, some basic methodological aspects of these simulations are briefly summarized (single-spin flip vs. cluster algorithms, finite-size scaling concepts), and then the application of these techniques to the nearest-neighbor Ising model in d=3 and 5 dimensions is described, and a detailed comparison to theoretical predictions is made. In addition, the case of Ising models with a large but finite range of interaction and the crossover scaling from mean-field behavior to the Ising universality class are treated. If one considers instead a long-range interaction described by a power-law decay, new classes of critical behavior depending on the exponent of this power law become accessible, and a stringent test of the ε-expansion becomes possible. As a final type of crossover from mean-field type behavior to two-dimensional Ising behavior, the interface localization-delocalization transition of Ising films confined between “competing” walls is considered. This problem is still hampered by questions regarding the appropriate coarse-grained model for the fluctuating interface near a wall, which is the starting point for both this problem and the theory of critical wetting.

  19. Analytic Solution of the Three-Variable Dynamical Equations of Oscillation Phenomena in B-Z Reaction

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dynamical behaviour of the inorganic bromate oscillator catalyzed by manganese ions in the B-Z reaction is discussed, a three-variable nonlinear dynamical equations of the oscillation phenomena have been obtained, and an analytic solution and numerical results of the equations are given.

  20. Non-linear hydrotectonic phenomena: Part I - fluid flow in open fractures under dynamical stress loading

    Energy Technology Data Exchange (ETDEWEB)

    Archambeau, C.B. [Univ. of Colorado, Boulder, CO (United States)

    1994-01-01

    A fractured solid under stress loading (or unloading) can be viewed as behaving macroscopically as a medium with internal, hidden, degrees of freedom, wherein changes in fracture geometry (i.e. opening, closing and extension) and flow of fluid and gas within fractures will produce major changes in stresses and strains within the solid. Likewise, the flow process within fractures will be strongly coupled to deformation within the solid through boundary conditions on the fracture surfaces. The effects in the solid can, in part, be phenomenologically represented as inelastic or plastic processes in the macroscopic view. However, there are clearly phenomena associated with fracture growth and open fracture fluid flows that produce effects that can not be described using ordinary inelastic phenomenology. This is evident from the fact that a variety of energy release phenomena can occur, including seismic emissions of previously stored strain energy due to fracture growth, release of disolved gas from fluids in the fractures resulting in enhanced buoyancy and subsequent energetic flows of gas and fluids through the fracture system which can produce raid extension of old fractures and the creation of new ones. Additionally, the flows will be modulated by the opening and closing of fractures due to deformation in the solid, so that the flow process is strongly coupled to dynamical processes in the surrounding solid matrix, some of which are induced by the flow itself.

  1. The theory of critical phenomena an introduction to the renormalization group

    CERN Document Server

    Binney, J J; Fisher, A J; Newman, M E J

    1993-01-01

    The successful calculation of critical exponents for continuous phase transitions is one of the main achievements of theoretical physics over the last quarter-century. This was achieved through the use of scaling and field-theoretic techniques which have since become standard equipment in many areas of physics, especially quantum field theory. This book provides a thorough introduction to these techniques. Continuous phase transitions are introduced, then the necessary statistical mechanics is summarized, followed by standard models, some exact solutions and techniques for numerical simulation

  2. Phase transition and critical phenomena of black holes: A general approach

    CERN Document Server

    Mandal, Abhijit; Majhi, Bibhas Ranjan

    2016-01-01

    We give some universal results for the phase transition of a black hole. Assuming that there is a phase transition, it is shown that without invoking any specific black hole, the critical exponents and the scaling powers can be obtained. We find that the values are exactly same which were calculated by taking explicit forms of different black hole spacetimes. The reason for this universality is also explained. The implication of the analysis is -- {\\it one does not need to investigate this problem case by case}, what the people are doing right now. We also observe that these, except two such quantities, are independent of the details of the spacetime dimensions.

  3. Phase transition and critical phenomena of black holes: A general approach

    Science.gov (United States)

    Mandal, Abhijit; Samanta, Saurav; Majhi, Bibhas Ranjan

    2016-09-01

    We present a general framework to study the phase transition of a black hole. Assuming that there is a phase transition, it is shown that without invoking any specific black hole, the critical exponents and the scaling powers can be obtained. We find that the values, which were calculated by taking explicit forms of different black hole spacetimes, are exactly the same. The reason for this universality is also explained. The implication of the analysis is that one does not need to investigate this problem case by case, as researchers are doing right now. We also observe that these values, except for two such quantities, are independent of the details of the spacetime dimensions.

  4. Phenomena at the QCD phase transition in nonequilibrium chiral fluid dynamics (NχFD)

    Energy Technology Data Exchange (ETDEWEB)

    Nahrgang, Marlene [Duke University, Department of Physics, Durham, NC (United States); Herold, Christoph [Suranaree University of Technology, School of Physics, Nakhon Ratchasima (Thailand)

    2016-08-15

    Heavy-ion collisions performed in the beam energy range accessible by the NICA collider facility are expected to produce systems of extreme net-baryon densities and can thus reach yet unexplored regions of the QCD phase diagram. Here, one expects the phase transition between the plasma of deconfined quarks and gluons and the hadronic matter to be of first order. A discovery of the first-order phase transition would as well prove the existence of the QCD critical point, a landmark in the phase diagram. In order to understand possible signals of the first-order phase transition in heavy-ion collision experiments it is very important to develop dynamical models of the phase transition. Here, we discuss the opportunities of studying dynamical effects at the QCD first-order phase transition within our model of nonequilibrium chiral fluid dynamics. (orig.)

  5. Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

    Science.gov (United States)

    Kimura, M.; Suhara, T.; Kanada-En'yo, Y.

    2016-12-01

    We present a review of recent works on clustering phenomena in unstable nuclei studied by antisymmetrized molecular dynamics (AMD). The AMD studies in these decades have uncovered novel types of clustering phenomena brought about by the excess neutrons. Among them, this review focuses on the molecule-like structure of unstable nuclei. One of the earliest discussions on the clustering in unstable nuclei was made for neutron-rich Be and B isotopes. AMD calculations predicted that the ground state clustering is enhanced or reduced depending on the number of excess neutrons. Today, the experiments are confirming this prediction as the change of the proton radii. Behind this enhancement and reduction of the clustering, there are underlying shell effects called molecular and atomic orbits. These orbits form covalent and ionic bonding of the clusters analogous to the atomic molecules. It was found that this "molecular-orbit picture" reasonably explains the low-lying spectra of Be isotopes. The molecular-orbit picture is extended to other systems having parity asymmetric cluster cores and to the three cluster systems. O and Ne isotopes are the candidates of the former, while the 3 α linear chains in C isotopes are the latter. For both subjects, many intensive studies are now in progress. We also pay a special attention to the observables which are the fingerprint of the clustering. In particular, we focus on the monopole and dipole transitions which are recently regarded as good probe for the clustering. We discuss how they have and will reveal the exotic clustering.

  6. Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, M. [Hokkaido University, Department of Physics, Sapporo (Japan); Hokkaido University, Nuclear Reaction Data Centre, Faculty of Science, Sapporo (Japan); Suhara, T. [Matsue College of Technology, Matsue (Japan); Kanada-En' yo, Y. [Kyoto University, Department of Physics, Kyoto (Japan)

    2016-12-15

    We present a review of recent works on clustering phenomena in unstable nuclei studied by antisymmetrized molecular dynamics (AMD). The AMD studies in these decades have uncovered novel types of clustering phenomena brought about by the excess neutrons. Among them, this review focuses on the molecule-like structure of unstable nuclei. One of the earliest discussions on the clustering in unstable nuclei was made for neutron-rich Be and B isotopes. AMD calculations predicted that the ground state clustering is enhanced or reduced depending on the number of excess neutrons. Today, the experiments are confirming this prediction as the change of the proton radii. Behind this enhancement and reduction of the clustering, there are underlying shell effects called molecular and atomic orbits. These orbits form covalent and ionic bonding of the clusters analogous to the atomic molecules. It was found that this ''molecular-orbit picture'' reasonably explains the low-lying spectra of Be isotopes. The molecular-orbit picture is extended to other systems having parity asymmetric cluster cores and to the three cluster systems. O and Ne isotopes are the candidates of the former, while the 3α linear chains in C isotopes are the latter. For both subjects, many intensive studies are now in progress. We also pay a special attention to the observables which are the fingerprint of the clustering. In particular, we focus on the monopole and dipole transitions which are recently regarded as good probe for the clustering. We discuss how they have and will reveal the exotic clustering. (orig.)

  7. Self-Organized Criticality in Small-World Networks Based on the Social Balance Dynamics

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-Kuan

    2011-01-01

    A node model is proposed to study the self-organized criticality in the small-world networks which represent the social networks. Based on the node model and the social balance dynamics, the social networks are mapped to the thermodynamic systems and the phenomena are studied with physical methods. It is found that the avalanche in the small-world networks at the critical state satisfies the power-law distribution spatially and temporally.%A node model is proposed to study the self-organized criticality in the small-world networks which represent the social networks.Based on the node model and the social balance dynamics,the social networks are mapped to the thermodynamic systems and the phenomena are studied with physical methods.It is found that the avalanche in the small-world networks at the critical state satisfies the power-law distribution spatially and temporally.The balance dynamics on social networks[1] based on the notion of social balance has been studied.[2-4]In Ref.[2],the authors studied the triad balance dynamic on a completely connected network representing a social network.At each step,they choose a triad relation from the social network and let it evolve.When the network gets dynamically balanced,they will reach the distributions of each triad relation.Moreover,other researchers subsequently carried out several studies on balance dynamics.[5,6]In this Letter,a node model is proposed to describe the triad relations,so the edge relations in Ref.[2] are changed to node relations,which may be more a universal method to study the phenomena in social networks.We will introduce the node model later.

  8. Classifying the expansion kinetics and critical surface dynamics of growing cell populations

    CERN Document Server

    Block, M; Drasdo, D

    2006-01-01

    Based on a cellular automaton model the growth kinetics and the critical surface dynamics of cell monolayers is systematically studied by variation of the cell migration activity, the size of the proliferation zone and the cell cycle time distribution over wide ranges. The model design avoids lattice artifacts and ensures high performance. The monolayer expansion velocity derived from our simulations can be interpreted as a generalization of the velocity relationship for a traveling front in the Fisher-Kolmogorov-Petrovskii-Piskounov (FKPP) equation that is frequently used to model tumor growth phenomena by continuum models. The critical surface dynamics corresponds to the Kardar-Parisi-Zhang (KPZ) universality class for all parameters and model variations studied. While the velocity agrees quantitatively with experimental observations by Bru et al, the critical surface dynamics is in contrast to their interpretation as generic molecular-beam-epitaxy-like growth.

  9. Nonlinear Phenomena in the Single-Mode Dynamics in an AFM Cantilever Beam

    KAUST Repository

    Ruzziconi, Laura

    2016-12-05

    profiles and integrity charts are drawn. The curves of constant percentage of integrity measure are detected, highlighting that they provide valuable quantitative information about the changes in the structural safety. Robustness as well as vulnerability to disturbances is examined. The practical range of existence of each branch is observed to be smaller, and sometimes remarkably smaller than the theoretical one. The issue of the dynamical integrity analysis in the AFM design is addressed, showing that these curves may be used to establish safety factors in order to operate the AFM according to the desired outcome, depending on the expected disturbances. Physical meaning and practical relevance of the nonlinear phenomena in the AFM engineering design are discussed.

  10. A consistent and unified picture for critical phenomena of $f(R)$ AdS black holes

    CERN Document Server

    Mo, Jie-Xiong; Wu, Yu-Cheng

    2016-01-01

    A consistent and unified picture for critical phenomena of charged AdS black holes in $f(R)$ gravity is drawn in this paper. Firstly, we investigate the phase transition in canonical ensemble. We derive the explicit solutions corresponding to the divergence of $C_Q$. The two solutions merge into one when the condition $Q_c=\\sqrt{\\frac{-1}{3R_0}}$ is satisfied. The curve of specific heat for $QQ_c$, the specific heat is always positive, implying the black holes are locally stable and no phase transition will take place. Secondly, both the $T-r_+$ curve and $T-S$ curve $f(R)$ AdS black holes are investigated and they exhibit Van der Vaals like behavior as the $P-v$ curve in the former research. Critical physical quantities are obtained and they are consistent with those derived from the specific heat analysis. We carry out numerical check of Maxwell equal area law for the cases $Q=0.2Q_c, 0.4Q_c, 0.6Q_c, 0.8Q_c$. The relative errors are amazingly small and can be negligible. So the Maxwell equal area law holds ...

  11. Two-phase DNS of evaporating drops with 3D phenomena and contact-line dynamics

    Science.gov (United States)

    Valluri, Prashant; Sáenz, Pedro J.; Sefiane, Khellil; Matar, Omar K.

    2014-11-01

    A novel 3D two-phase model based on the diffuse-interface method is developed to investigate the fully-coupled two-phase dynamics of a sessile drop undergoing evaporation on a heated substrate. General transient advection-diffusion transport equations are implemented to address the conservation of energy and vapour in the gas phase, which also allows the more realistic modelling of interface mass and energy transport based on local conditions. The emphasis of this investigation is on addressing three-dimensional phenomena during evaporation of drops with non-circular contact area. Irregular drops lead to complex interface shapes with intricate contract-angle distributions along the triple line and with a three-dimensional flow which previous axisymmetric approaches cannot show. The versatility of this model also allows the simulation of the more complex case of drops evaporating with a moving contact line. Both constant-angle (CA) and constant-radius (CR) modes of pure evaporation are successfully simulated and validated against experiments. ThermaPOWER project (EU IRSES-PIRSES GA-2011-294905).

  12. Full data acquisition in Kelvin Probe Force Microscopy: Mapping dynamic electric phenomena in real space

    Science.gov (United States)

    Collins, Liam; Belianinov, Alex; Somnath, Suhas; Balke, Nina; Kalinin, Sergei V.; Jesse, Stephen

    2016-08-01

    Kelvin probe force microscopy (KPFM) has provided deep insights into the local electronic, ionic and electrochemical functionalities in a broad range of materials and devices. In classical KPFM, which utilizes heterodyne detection and closed loop bias feedback, the cantilever response is down-sampled to a single measurement of the contact potential difference (CPD) per pixel. This level of detail, however, is insufficient for materials and devices involving bias and time dependent electrochemical events; or at solid-liquid interfaces, where non-linear or lossy dielectrics are present. Here, we demonstrate direct recovery of the bias dependence of the electrostatic force at high temporal resolution using General acquisition Mode (G-Mode) KPFM. G-Mode KPFM utilizes high speed detection, compression, and storage of the raw cantilever deflection signal in its entirety at high sampling rates. We show how G-Mode KPFM can be used to capture nanoscale CPD and capacitance information with a temporal resolution much faster than the cantilever bandwidth, determined by the modulation frequency of the AC voltage. In this way, G-Mode KPFM offers a new paradigm to study dynamic electric phenomena in electroactive interfaces as well as a promising route to extend KPFM to the solid-liquid interface.

  13. Dynamical Study of Multifragmentation and Related Phenomena in Heavy-Ion Collisions

    CERN Document Server

    Vermani, Yogesh K

    2010-01-01

    In the first part of thesis, we shall deal with fragment emission in central collisions studied as a function of beam energy and system mass. Central collisions are also important candidate in view of exploring collective expansion and squeeze out phenomena \\cite{dan93}. We have simulated the central collisions of $^{20}Ne+^{20}Ne$, $^{40}Ar+^{45}Sc$, $^{58}Ni+^{58}Ni$, $^{86}Kr+^{93}Nb$, $^{129}Xe+^{124}Sn$, and $^{197}Au+^{197}Au$. Peak IMF multiplicity is observed to follow power law of form: $c A^{\\tau}_{tot}$, with exponent $\\tau$ close to unity. Next we try to understand the clusterization mechanism in spectator matter fragmentation using \\emph{simulated annealing clusterization algorithm} (SACA) advanced by Puri \\emph{et al}. Earlier recognition of fragments structure (around 60 fm/c) also points towards dynamical origin of fragments. We shall also highlight the importance of momentum dependent interactions in probing nuclear EoS via intermediate energy heavy-ion collisions. Estimation of baryonic entr...

  14. Quantification of surface displacements and electromechanical phenomena via dynamic atomic force microscopy

    Science.gov (United States)

    Balke, Nina; Jesse, Stephen; Yu, Pu; Carmichael, Ben; Kalinin, Sergei V.; Tselev, Alexander

    2016-10-01

    Detection of dynamic surface displacements associated with local changes in material strain provides access to a number of phenomena and material properties. Contact resonance-enhanced methods of atomic force microscopy (AFM) have been shown capable of detecting ˜1-3 pm-level surface displacements, an approach used in techniques such as piezoresponse force microscopy, atomic force acoustic microscopy, and ultrasonic force microscopy. Here, based on an analytical model of AFM cantilever vibrations, we demonstrate a guideline to quantify surface displacements with high accuracy by taking into account the cantilever shape at the first resonant contact mode, depending on the tip-sample contact stiffness. The approach has been experimentally verified and further developed for piezoresponse force microscopy (PFM) using well-defined ferroelectric materials. These results open up a way to accurate and precise measurements of surface displacement as well as piezoelectric constants at the pm-scale with nanometer spatial resolution and will allow avoiding erroneous data interpretations and measurement artifacts. This analysis is directly applicable to all cantilever-resonance-based scanning probe microscopy (SPM) techniques.

  15. Conserved nonlocal dynamics and critical behavior of uranium ferromagnetic superconductors.

    Science.gov (United States)

    Singh, Rohit; Dutta, Kishore; Nandy, Malay K

    2017-01-01

    A recent theoretical study [Phys. Rev. Lett. 112, 037202 (2014)10.1103/PhysRevLett.112.037202] has revealed that systems such as uranium ferromagnetic superconductors obey conserved dynamics. To capture the critical behavior near the paramagnetic to ferromagnetic phase transition of these compounds, we study the conserved critical dynamics of a nonlocal Ginzburg-Landau model. A dynamic renormalization-group calculation at one-loop order yields the critical indices in the leading order of ε=d_{c}-d, where d_{c}=4-2ρ is the upper critical dimension, with ρ an exponent in the nonlocal interaction. The predicted static critical exponents are found to be comparable with the available experimentally observed critical exponents for strongly uniaxial uranium ferromagnetic superconductors. The corresponding dynamic exponent z and linewidth exponent w are found to be z=4-ρε/4+O(ε^{2}) and w=1+ρ+3ε/4+O(ε^{2}).

  16. Conserved nonlocal dynamics and critical behavior of uranium ferromagnetic superconductors

    Science.gov (United States)

    Singh, Rohit; Dutta, Kishore; Nandy, Malay K.

    2017-01-01

    A recent theoretical study [Phys. Rev. Lett. 112, 037202 (2014), 10.1103/PhysRevLett.112.037202] has revealed that systems such as uranium ferromagnetic superconductors obey conserved dynamics. To capture the critical behavior near the paramagnetic to ferromagnetic phase transition of these compounds, we study the conserved critical dynamics of a nonlocal Ginzburg-Landau model. A dynamic renormalization-group calculation at one-loop order yields the critical indices in the leading order of ɛ =dc-d , where dc=4 -2 ρ is the upper critical dimension, with ρ an exponent in the nonlocal interaction. The predicted static critical exponents are found to be comparable with the available experimentally observed critical exponents for strongly uniaxial uranium ferromagnetic superconductors. The corresponding dynamic exponent z and linewidth exponent w are found to be z =4 -ρ ɛ /4 +O (ɛ2) and w =1 +ρ +3 ɛ /4 +O (ɛ2) .

  17. cDPD: A new dissipative particle dynamics method for modeling electrokinetic phenomena at the mesoscale

    Science.gov (United States)

    Deng, Mingge; Li, Zhen; Borodin, Oleg; Karniadakis, George Em

    2016-10-01

    We develop a "charged" dissipative particle dynamics (cDPD) model for simulating mesoscopic electrokinetic phenomena governed by the stochastic Poisson-Nernst-Planck and the Navier-Stokes equations. Specifically, the transport equations of ionic species are incorporated into the DPD framework by introducing extra degrees of freedom and corresponding evolution equations associated with each DPD particle. Diffusion of ionic species driven by the ionic concentration gradient, electrostatic potential gradient, and thermal fluctuations is captured accurately via pairwise fluxes between DPD particles. The electrostatic potential is obtained by solving the Poisson equation on the moving DPD particles iteratively at each time step. For charged surfaces in bounded systems, an effective boundary treatment methodology is developed for imposing both the correct hydrodynamic and electrokinetics boundary conditions in cDPD simulations. To validate the proposed cDPD model and the corresponding boundary conditions, we first study the electrostatic structure in the vicinity of a charged solid surface, i.e., we perform cDPD simulations of the electrostatic double layer and show that our results are in good agreement with the well-known mean-field theoretical solutions. We also simulate the electrostatic structure and capacity densities between charged parallel plates in salt solutions with different salt concentrations. Moreover, we employ the proposed methodology to study the electro-osmotic and electro-osmotic/pressure-driven flows in a micro-channel. In the latter case, we simulate the dilute poly-electrolyte solution drifting by electro-osmotic flow in a micro-channel, hence demonstrating the flexibility and capability of this method in studying complex fluids with electrostatic interactions at the micro- and nano-scales.

  18. Critical dynamics a field theory approach to equilibrium and non-equilibrium scaling behavior

    CERN Document Server

    Täuber, Uwe C

    2014-01-01

    Introducing a unified framework for describing and understanding complex interacting systems common in physics, chemistry, biology, ecology, and the social sciences, this comprehensive overview of dynamic critical phenomena covers the description of systems at thermal equilibrium, quantum systems, and non-equilibrium systems. Powerful mathematical techniques for dealing with complex dynamic systems are carefully introduced, including field-theoretic tools and the perturbative dynamical renormalization group approach, rapidly building up a mathematical toolbox of relevant skills. Heuristic and qualitative arguments outlining the essential theory behind each type of system are introduced at the start of each chapter, alongside real-world numerical and experimental data, firmly linking new mathematical techniques to their practical applications. Each chapter is supported by carefully tailored problems for solution, and comprehensive suggestions for further reading, making this an excellent introduction to critic...

  19. Partial dynamical symmetry at critical points of quantum phase transitions.

    Science.gov (United States)

    Leviatan, A

    2007-06-15

    We show that partial dynamical symmetries can occur at critical points of quantum phase transitions, in which case underlying competing symmetries are conserved exactly by a subset of states, and mix strongly in other states. Several types of partial dynamical symmetries are demonstrated with the example of critical-point Hamiltonians for first- and second-order transitions in the framework of the interacting boson model, whose dynamical symmetries correspond to different shape phases in nuclei.

  20. Studies of Phase Transitions and Critical Phenomena: I. Origin of Broken Particle-Hole Symmetry in Critical Fluids. I. Phase Transitions of Interacting Membranes.

    Science.gov (United States)

    Goldstein, Raymond Ethan

    The longstanding problem of the precise correspondence between critical phenomena in fluids and ferromagnets is resolved in Part I through a synthesis of mean field theory, exact results for lattice models, field-theoretic techniques, and by extensive quantitative comparison with experiment. Emphasis is placed on the origin of broken particle-hole symmetry in fluids as reflected in the form of the critical point scaling fields and in systematic variations in certain nonuniversal critical amplitudes with molecular polarizability. Those trends and the degree to which the scaling axes are linearly mixed versions of the bare "thermal" and "magnetic" fields in particle-hole symmetric systems are shown both for lattice models and real fluids to be intimately related to the presence of many-body interactions of the Axilrod-Teller type. A quantitatively accurate microscopic expression for the field-mixing operator of fluids is derived on the basis of an exact Hubbard-Stratonovich transformation relating the fluid Hamiltonian to that of a Landau-Ginzburg-Wilson model. A phenomenological theory of the phase behavior of multilamellar liquid crystals of hydrated phospholipid bilayers is developed in Part II, and its predictions tested by extensive comparison with experiment. A Ginzburg-Landau free energy functional based on the elastic properties of two coupled monolayers is proposed to describe intrabilayer ordering, and the phenomenon of structural phase transitions driven by membrane interactions is described by incorporating in addition the attractive dispersion interactions and repulsive "hydration" forces acting between membranes. The theory indicates and experiments support a connection between the pseudocriticality of the bilayer transitions and the large susceptibility of the in-plane order to membrane interactions. The pseudocriticality in turn is suggested to arise from the analog of a capillary critical point accessible by finite-size effects. Theoretical phase

  1. Static and dynamic critical behavior of thin magnetic Ising films

    Science.gov (United States)

    Sabogal-Suárez, D.; Alzate-Cardona, J. D.; Restrepo-Parra, E.

    2015-09-01

    This work presents a study of the effect of film thickness on the static and dynamic critical behavior of thin magnetic Ising films. Monte Carlo simulations using the Wolff algorithm were performed to determine the static and dynamic critical exponents of the films. A dimensionality crossover from 2D to 3D (due to the finiteness of the films) in the static and dynamic critical behavior was observed as the film thickness increases. In addition, a slight increase in the effective dimension deff and a considerable increase in the critical temperature Tc(∞) were found. Small values for the dynamic critical exponents were obtained, indicating that the Wolff algorithm is a very efficient method for these magnetic systems.

  2. Generalized dynamic scaling for quantum critical relaxation in imaginary time.

    Science.gov (United States)

    Zhang, Shuyi; Yin, Shuai; Zhong, Fan

    2014-10-01

    We study the imaginary-time relaxation critical dynamics of a quantum system with a vanishing initial correlation length and an arbitrary initial order parameter M0. We find that in quantum critical dynamics, the behavior of M0 under scale transformations deviates from a simple power law, which was proposed for very small M0 previously. A universal characteristic function is then suggested to describe the rescaled initial magnetization, similar to classical critical dynamics. This characteristic function is shown to be able to describe the quantum critical dynamics in both short- and long-time stages of the evolution. The one-dimensional transverse-field Ising model is employed to numerically determine the specific form of the characteristic function. We demonstrate that it is applicable as long as the system is in the vicinity of the quantum critical point. The universality of the characteristic function is confirmed by numerical simulations of models belonging to the same universality class.

  3. Granular dynamics simulation of segregation phenomena in bubbling gas-fluidised beds

    NARCIS (Netherlands)

    Hoomans, B.P.B.; Kuipers, J.A.M.; Swaaij, van W.P.M.

    2000-01-01

    A hard-sphere discrete particle model of a gas-fluidised bed was used in order to simulate segregation phenomena in systems consisting of particles of different sizes. In the model, the gas-phase hydrodynamics is described by the spatially averaged Navier¿Stokes equations for two-phase flow. For eac

  4. A Comparison of Critical Regimes in Collapsible Tube, Pipe, Open Channel and Gas-Dynamic Flows

    Science.gov (United States)

    Arun, C. P.

    2003-11-01

    Though of considerable interest to clinical scientists, collapsible tubes are only recently receiving due interest by fluid physicists. The subject of critical phenomena in collapsible tube flow appears not to have been examined critically. For example, it has been proposed in the past that shock waves in physiological tubes are abnormal. We propose a classification of flow through collapsible tubes recognising that compressibility in gas-dynamic and pipe flow (cf.waterhammer) corresponds to distensibility in collapsible tube flow. Thus, opening and closing waves of collapsible tube flow (predistension regime) is subcritical flow and the post-distension regime, supercritical. Physiological tubes are often hyperelastic and contractile and often, when distension is very significant, a hypercritical regime corresponding to hypersonic gas-dynamic flow is admissible. Such a hypercritical regime would allow storage of energy and muscle contraction in the wall of the tube and hence continuance of propulsion in the essentially intermittent flow that is seen in collapsible tubes. Such a mechanism appears to be in operation in the human aorta, bowel and urethra. The present work offers a comparison of critical regimes in various fluid flow situations including collapsible tubes, that is in harmony with known phenomena seen in nature.

  5. Overview of Approaches to Incorporate Dynamics into the Measurement of Complex Phenomena with the Use of Composite Indices

    Directory of Open Access Journals (Sweden)

    Anna Łatuszyńska

    2012-06-01

    Full Text Available Composite indices have substantially gained in popularity in recent years. Despite their alleged disadvantages, they appear to be very useful in measuring the level of certain phenomena that are too complex to express with a single indicator. Most rankings based on composite indicators are created at regular intervals, such as every month, every quarter or every year. A common approach is to base rankings solely on the most current values of single indicators, making no reference to previous results. The absence of dynamics from such measurements deprives studies of information on change in these phenomena and may limit the stability of classifications. This article presents the possibility of creating reliable, dynamic rankings of measured items and measuring the complex phenomena with the use of composite indices. Potential solutions are presented on the basis of a review of the international literature. Some advantages and disadvantages of the presented solutions are described and an example of a new approach is shown.

  6. Hilbert-Glass Transition: New Universality of Temperature-Tuned Many-Body Dynamical Quantum Criticality

    Directory of Open Access Journals (Sweden)

    David Pekker

    2014-03-01

    Full Text Available We study a new class of unconventional critical phenomena that is characterized by singularities only in dynamical quantities and has no thermodynamic signatures. One example of such a transition is the recently proposed many-body localization-delocalization transition, in which transport coefficients vanish at a critical temperature with no singularities in thermodynamic observables. Describing this purely dynamical quantum criticality is technically challenging as understanding the finite-temperature dynamics necessarily requires averaging over a large number of matrix elements between many-body eigenstates. Here, we develop a real-space renormalization group method for excited states that allows us to overcome this challenge in a large class of models. We characterize a specific example: the 1 D disordered transverse-field Ising model with generic interactions. While thermodynamic phase transitions are generally forbidden in this model, using the real-space renormalization group method for excited states we find a finite-temperature dynamical transition between two localized phases. The transition is characterized by nonanalyticities in the low-frequency heat conductivity and in the long-time (dynamic spin correlation function. The latter is a consequence of an up-down spin symmetry that results in the appearance of an Edwards-Anderson-like order parameter in one of the localized phases.

  7. Magneto-Fluid Dynamics Fundamentals and Case Studies of Natural Phenomena

    CERN Document Server

    Lorrain, Paul; Houle, Stéphane

    2006-01-01

    This book concerns the generation of electric currents and of electric space charges inside conducting media that move in magnetic fields. The authors postulate nothing but the Maxwell equations. They discuss at length the disk dynamo, which serves as a model for the natural self-excited dynamos that generate magnetic fields such as that of sunspots. There are 36 Examples and 13 Case Studies. The Case Studies concern solar phenomena -- magnetic elements, sunspots, spicules, coronal loops -- and the Earth's magnetic field.

  8. Can dynamical synapses produce true self-organized criticality?

    Science.gov (United States)

    Costa, Ariadne de Andrade; Copelli, Mauro; Kinouchi, Osame

    2015-06-01

    Neuronal networks can present activity described by power-law distributed avalanches presumed to be a signature of a critical state. Here we study a random-neighbor network of excitable cellular automata coupled by dynamical synapses. The model exhibits a very similar to conservative self-organized criticality (SOC) models behavior even with dissipative bulk dynamics. This occurs because in the stationary regime the model is conservative on average, and, in the thermodynamic limit, the probability distribution for the global branching ratio converges to a delta-function centered at its critical value. So, this non-conservative model pertain to the same universality class of conservative SOC models and contrasts with other dynamical synapses models that present only self-organized quasi-criticality (SOqC). Analytical results show very good agreement with simulations of the model and enable us to study the emergence of SOC as a function of the parametric derivatives of the stationary branching ratio.

  9. Run-time Phenomena in Dynamic Software Updating: Causes and Effects

    DEFF Research Database (Denmark)

    Gregersen, Allan Raundahl; Jørgensen, Bo Nørregaard

    2011-01-01

    The development of a dynamic software updating system for statically-typed object-oriented programming languages has turned out to be a challenging task. Despite the fact that the present state of the art in dynamic updating systems, like JRebel, Dynamic Code Evolution VM, JVolve and Javeleon, al...

  10. New techniques for the characterisation of dynamical phenomena in solar coronal images

    Science.gov (United States)

    Robbrecht, E.

    2007-02-01

    ) was an important step on the way to subarcsecond telescopes. It allows a spatial resolution of 1" in the EUV and UV bands and, simultaneously, a temporal resolution of the order of a few seconds. Coronal physics studies are dominated by two major and interlinked problems: coronal heating and solar wind acceleration. Above the chromosphere there is a thin transition layer in which the temperature suddenly increases and density drops. How can the temperature of the solar corona be three orders of magnitude higher than the temperature of the photosphere? In order for this huge temperature gradient to be stationary, non-thermal energy must be transported from below the photosphere towards the chromosphere and corona and converted into heat to balance the radiative and conductive losses. This puzzle of origin, transport and conversion of energy is referred to as the "coronal heating problem". Due to its fundamental role in the structuring of the corona, the magnetic field is supposed to play an important role in the heating. In this dissertation we describe two aspects of solar coronal dynamics: waves in coronal loops (Part I) and coronal mass ejections (Part II). We investigate the influence of (semi-) automated techniques on solar coronal research. This is a timely discussion since the observation of solar phenomena is transitioning from manual detection to "Solar Image Processing". Our results are mainly based on images from the Extreme UV Imaging Telescope (EIT) and the Large Angle and Spectrometric Coronagraph (LASCO), two instruments onboard the satellite SOHO (Solar and Heliospheric Observatory) of which we recently celebrated its 11th anniversary. The high quality of the images together with the long timespan created a valuable database for solar physics research. Part I reports on the first detection of slow magnetoacoustic waves in transequatorial coronal loops observed in high cadence image sequences simultaneously produced by EIT and TRACE (Transition Region

  11. Analysis of faults stability with dynamic phenomena in the mine based on slide criterion and in-situ stress measurement

    Institute of Scientific and Technical Information of China (English)

    SONG Wei-hua; WANG Yu-feng; WANG Xin-hua

    2008-01-01

    For the study on the relationship between the dynamic phenomena in the mining such as mine earthquakes,outburst and faults slide,firstly,double shear friction experiments of sandstone were made,and its slide criterion was suggested considering the viewing of engineering.Secondly,in order to study the stability of underground rock and zone of tectonic stress field,based on the analysis on distribution characteristic of initial rock stress measurements,the geology structural model was built and tectonic stress field was made a back-analysis by applying finite element method.The calculating results fit with the analysis result of earthquakes mechanism and the distribution characteristic of the measurements.The high stress regional centers station locates discontinuous zone of I level faults and is corresponding to underground earthquakes scene.From then it is certain that tectonic stress is the major origin and necessary condition of mine earthquakes.The instability slide of the faults is the main manifest and the mining activity is the leading factor.Beipiao fault has a dominate effect on other sub faults and tectonic stress area and is dynamical fountain of dynamic phenomena in the Beipiao Mines.

  12. Analysis of faults stability with dynamic phenomena in the mine based on slide criterion and in-situ stress measurement

    Institute of Scientific and Technical Information of China (English)

    SONG Wei-hua; WANG Yu-feng; WANG Xin-hua

    2008-01-01

    For the study on the relationshfp between the dynamic phenomena in the min-ing such as mine earthquakes, outburst and faults slide, firstly, double shear friction ex-periments of sandstone were made, and its slide criterion was suggested considering the viewing of engineering. Secondly, in order to study the stability of underground rock and zone of tectonic stress field, based on the analysis on distribution characteristic of initial rock stress measurements, the geology structural model was built and tectonic stress field was made a back-analysis by applying finite element method. The calculating results fit with the analysis result of earthquakes mechanism and the distribution characteristic of the measurements. The high stress regional centers station locates discontinuous zone of I level faults and is corresponding to underground earthquakes scene. From then it is cer-tain that tectonic stress is the major origin and necessary condition of mine earthquakes. The instability slide of the faults is the main manifest and the mining activity is the leading factor. Beipiao fault has a dominate effect on other sub faults and tectonic stress area and is dynamical fountain of dynamic phenomena in the Beipiao Mines.

  13. Dynamic Formulations and Beating Phenomena of Rotating Euler—Bernoulli Flexible Shafts

    Institute of Scientific and Technical Information of China (English)

    朱怀亮

    2002-01-01

    In this paper,the intrinsic behavior of rotating Euler-Benoulli flexible shafts was studied due to coupled bending and torsional vibratuions,the equations of motion of the shaft with unbalanced eccentricity and visous material damping were derived by the Hamilton principle.The numerical solution was obtained using the perturbation approach and mode-assuming method.The influences of the coupled vibrations between the benging and torsion.the rotaing speed,material damping and the slenderness ratio of the shaft were analyzed.It is clearly shown that the beating phenomena can occur when the interaction of torsion and flexure is considered.

  14. Dynamical net-proton fluctuations near a QCD critical point

    CERN Document Server

    Herold, Christoph; Yan, Yupeng; Kobdaj, Chinorat

    2016-01-01

    We investigate the evolution of the net-proton kurtosis and the kurtosis of the chiral order parameter near the critical point in the model of nonequilibrium chiral fluid dynamics. The order parameter is propagated explicitly and coupled to an expanding fluid of quarks and gluons in order to describe the dynamical situation in a heavy-ion collision. We study the critical region near the critical point on the crossover side. There are two sources of fluctuations: non-critical initial event-by-event fluctuations and critical fluctuations. These fluctuations can be distinguished by comparing a mean-field evolution of averaged thermodynamic quantities with the inclusion of fluctuations at the phase transition. We find that while the initial state fluctuations give rise to flat deviations from statistical fluctuations, critical fluctuations reveal a clear structure of the phase transition. The signals of the critical point in the net-proton and sigma field kurtosis are affected by the nonequilibrium dynamics and t...

  15. Schlieren visualization of fluid dynamics phenomena during phacosonication in cataract surgery

    Science.gov (United States)

    Serafino, Gabriella; Piuzzi, Barbara; Sanguinetti, G.; Sirotti, C.; Sirotti, Paolo; Tognetto, D.

    2005-03-01

    In ultrasonic phacoemulsification during cataract surgery the lens material fragmentation has been described as being caused by a combination of several mechanisms. The different theories involve tip vibration, acoustic waves produced by the tip, particles and liquids impact on the surface of the lens and cavitation. However the mechanisms are still not clear. To better understand phaco-related phenomena we have tried to produce a description in term of images of the cataract phacoemulsification procedure. An expanded and collimated laser diode beam transilluminates a transparent tube containing a liquid medium. The machine is activated separating the different phases of irrigation, aspiration and phacosonication. Fluid turbulences and phenomena related to the tip vibration constitute the phase images, visualized using Schlieren or similar techniques. The optical Fourier transform is filtered by a blade or by a black dot. The filtered transform is reconstructed into the visualized phase image and this is acquired by a digital image processing system. The presence of acoustic cavitation and possibly of ultrasonic radiation has been revealed. The technique promises to be a possible means for evaluation of single phaco apparatus power setting and comparison between different machines in terms of power modulation and cavitation production.

  16. NONLINEAR COMPLEX DYNAMIC PHENOMENA OF THE PERTURBED METALLIC BAR CONSIDERING DISSIPATING EFFECT

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang-hui; ZHANG Nian-mei; YANG Gui-tong

    2005-01-01

    Considering Peierls-Nabarro effect, one-dimensional finite metallic bar subjected with periodic field was researched under Neumann boundary condition. Dynamics of this system was described with displacement by perturbed sine-Gordon type equation.Finite difference scheme with fourth-order central differences in space and second-order central differences in time was used to simulate dynamic responses of this system. For the metallic bar with specified sizes and physical features, effect of amplitude of external driving on dynamic behavior of the bar was investigated under initial "breather" condition. Four kinds of typical dynamic behaviors are shown: x-independent simple harmonic motion;harmonic motion with single wave; quasi-periodic motion with single wave; temporal determine dynamic features.

  17. Universal short-time quantum critical dynamics in imaginary time

    Science.gov (United States)

    Yin, Shuai; Mai, Peizhi; Zhong, Fan

    2014-04-01

    We propose a scaling theory for the universal imaginary-time quantum critical dynamics for both short and long times. We discover that there exists a universal critical initial slip related to a small initial order parameter M0. In this stage, the order parameter M increases with the imaginary time τ as M ∝M0τθ with a universal initial-slip exponent θ. For the one-dimensional transverse-field Ising model, we estimate θ to be 0.373, which is markedly distinct from its classical counterpart. Apart from the local order parameter, we also show that the entanglement entropy exhibits universal behavior in the short-time region. As the critical exponents in the early stage and in equilibrium are identical, we apply the short-time dynamics method to determine quantum critical properties. The method is generally applicable in both the Landau-Ginzburg-Wilson paradigm and topological phase transitions.

  18. Critical points and dynamic systems with planar hexagonal symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ning [Faculty of Information and Control Engineering, Shenyang Jianzhu University, Shenyang 110168 (China)]. E-mail: n_chen@126.com; Meng Fan Yu [Faculty of Information and Control Engineering, Shenyang Jianzhu University, Shenyang 110168 (China)

    2007-05-15

    In this investigation, we detect and utilize critical points of functions with hexagonal symmetry in order to study their dynamics. The asymmetric unit in a parallelogram lattice is chosen as the initial searching region for a critical point set in a dynamic plane. The accelerated direct search algorithm is used within the parallelogram lattice to search for the critical points. Parameter space is separated into regions (chaotic, periodic or mixed) by the Ljapunov exponents of the critical points. Then the generalized Mandelbrot set (M-set), which is a cross-section of the parameter space, is constructed. Many chaotic attractors and filled-in Julia sets can be generated by using parameters from this kind of M-sets.

  19. Feature activated molecular dynamics: an efficient approach for atomistic simulation of solid-state aggregation phenomena.

    Science.gov (United States)

    Prasad, Manish; Sinno, Talid

    2004-11-01

    An efficient approach is presented for performing efficient molecular dynamics simulations of solute aggregation in crystalline solids. The method dynamically divides the total simulation space into "active" regions centered about each minority species, in which regular molecular dynamics is performed. The number, size, and shape of these regions is updated periodically based on the distribution of solute atoms within the overall simulation cell. The remainder of the system is essentially static except for periodic rescaling of the entire simulation cell in order to balance the pressure between the isolated molecular dynamics regions. The method is shown to be accurate and robust for the Environment-Dependant Interatomic Potential (EDIP) for silicon and an Embedded Atom Method potential (EAM) for copper. Several tests are performed beginning with the diffusion of a single vacancy all the way to large-scale simulations of vacancy clustering. In both material systems, the predicted evolutions agree closely with the results of standard molecular dynamics simulations. Computationally, the method is demonstrated to scale almost linearly with the concentration of solute atoms, but is essentially independent of the total system size. This scaling behavior allows for the full dynamical simulation of aggregation under conditions that are more experimentally realizable than would be possible with standard molecular dynamics.

  20. Investigations of the contact bounce behaviors and relative dynamic welding phenomena for electromechanical relay

    Science.gov (United States)

    Ren, Wanbin; He, Yuan; Jin, Jianbing; Man, Sida

    2016-06-01

    Dynamic welding, being the principal mechanism of sticking failure, correlates closely with the contact bounce of electromechanical relay. The typical waveforms of dynamic contact force and contact voltage at making and breaking process are obtained with the use of a new designed test rig. The variations in bounce time, bounce numbers, last bounce duration, and relevant welding force are investigated in the electrical endurance test. It is determined that the welding strength and the welding probability are increased with the reduced stationary force. The degradation physical mechanism is present to better understand the relationship between dynamic welding and operation characteristics of electromechanical relay.

  1. Shear-banding phenomena and dynamical behavior in a Laponite suspension

    Science.gov (United States)

    Ianni, F.; di Leonardo, R.; Gentilini, S.; Ruocco, G.

    2008-03-01

    Shear localization in an aqueous clay suspension of Laponite is investigated through dynamic light scattering, which provides access both to the dynamics of the system (homodyne mode) and to the local velocity profile (heterodyne mode). When shear bands form, a relaxation of the dynamics typical of a gel phase is observed in both bands soon after the flow stops. Periodic oscillations of the flow behavior, typical of a stick-slip phenomenon, are also observed when shear localization occurs. Both results are discussed in the light of various theoretical models for soft glassy gels.

  2. Dynamics of social contagions with heterogeneous adoption thresholds: Crossover phenomena in phase transition

    CERN Document Server

    Wang, Wei; Shu, Panpan; Wang, Zhen

    2015-01-01

    Heterogeneous adoption thresholds exist widely in social contagions, but were always neglected in previous studies. We first propose a non-Markovian spreading threshold model with general adoption threshold distribution. In order to understand the effects of heterogeneous adoption thresholds quantitatively, an edge-based compartmental theory is developed for the proposed model. We use a binary spreading threshold model as a specific example, in which some individuals have a low adoption threshold (i.e., activists) while the remaining ones hold a relatively high adoption threshold (i.e., bigots), to demonstrate that heterogeneous adoption thresholds markedly affect the final adoption size and phase transition. Interestingly, the first-order, second-order and hybrid phase transitions can be found in the system. More importantly, there are two different kinds of crossover phenomena in phase transition for distinct values of bigots' adoption threshold: a change from first-order or hybrid phase transition to the s...

  3. Modelling of Mass Transfer Phenomena in Chemical and Biochemical Reactor Systems using Computational Fluid Dynamics

    DEFF Research Database (Denmark)

    Larsson, Hilde Kristina

    are subsequently evaluated based on their applicability in the four case studies. The evaluations especially focus on the impact of the choice of turbulence model and other modelling decisions made by the user. The conclusion is that CFD is a highly valuable tool for modelling several important parameters...... are presented as well as the theory behind the SST and the k-ε turbulence models. Modelling of additional variables, porous materials and twophase flows are also introduced. The two-phase flows are modelled using the Euler-Euler method, and both dispersed and free-surface flows are simulated. The importance...... of mass transfer with a focus on mixing, gas-liquid transfer of oxygen, and heterogeneous reactor systems is reviewed and mathematical models for these applications are presented. A review of how these mass transfer phenomena have been modelled in the scientific literature is also included. The models...

  4. Microsimulations of Arching, Clogging, and Bursty Exit Phenomena in Crowd Dynamics

    CERN Document Server

    Castro, Francisco Enrique Vicente G

    2015-01-01

    We present in this paper the behavior of an artificial agent who is a member of a crowd. The behavior is based on the social comparison theory, as well as the trajectory mapping towards an agent's goal considering the agent's field of vision. The crowd of artificial agents were able to exhibit arching, clogging, and bursty exit rates. We were also able to observe a new phenomenon we called double arching, which happens towards the end of the simulation, and whose onset is exhibited by a "calm" density graph within the exit passage. The density graph is usually bursty at this area. Because of these exhibited phenomena, we can use these agents with high confidence to perform microsimulation studies for modeling the behavior of humans and objects in very realistic ways.

  5. Criticality in conserved dynamical systems: Experimental observation vs. exact properties

    Science.gov (United States)

    Marković, Dimitrije; Gros, Claudius; Schuelein, André

    2013-03-01

    Conserved dynamical systems are generally considered to be critical. We study a class of critical routing models, equivalent to random maps, which can be solved rigorously in the thermodynamic limit. The information flow is conserved for these routing models and governed by cyclic attractors. We consider two classes of information flow, Markovian routing without memory and vertex routing involving a one-step routing memory. Investigating the respective cycle length distributions for complete graphs, we find log corrections to power-law scaling for the mean cycle length, as a function of the number of vertices, and a sub-polynomial growth for the overall number of cycles. When observing experimentally a real-world dynamical system one normally samples stochastically its phase space. The number and the length of the attractors are then weighted by the size of their respective basins of attraction. This situation is equivalent, for theory studies, to "on the fly" generation of the dynamical transition probabilities. For the case of vertex routing models, we find in this case power law scaling for the weighted average length of attractors, for both conserved routing models. These results show that the critical dynamical systems are generically not scale-invariant but may show power-law scaling when sampled stochastically. It is hence important to distinguish between intrinsic properties of a critical dynamical system and its behavior that one would observe when randomly probing its phase space.

  6. Criticality in conserved dynamical systems: experimental observation vs. exact properties.

    Science.gov (United States)

    Marković, Dimitrije; Gros, Claudius; Schuelein, André

    2013-03-01

    Conserved dynamical systems are generally considered to be critical. We study a class of critical routing models, equivalent to random maps, which can be solved rigorously in the thermodynamic limit. The information flow is conserved for these routing models and governed by cyclic attractors. We consider two classes of information flow, Markovian routing without memory and vertex routing involving a one-step routing memory. Investigating the respective cycle length distributions for complete graphs, we find log corrections to power-law scaling for the mean cycle length, as a function of the number of vertices, and a sub-polynomial growth for the overall number of cycles. When observing experimentally a real-world dynamical system one normally samples stochastically its phase space. The number and the length of the attractors are then weighted by the size of their respective basins of attraction. This situation is equivalent, for theory studies, to "on the fly" generation of the dynamical transition probabilities. For the case of vertex routing models, we find in this case power law scaling for the weighted average length of attractors, for both conserved routing models. These results show that the critical dynamical systems are generically not scale-invariant but may show power-law scaling when sampled stochastically. It is hence important to distinguish between intrinsic properties of a critical dynamical system and its behavior that one would observe when randomly probing its phase space.

  7. Change Phenomena of Spatial Physical in the Dynamics of Development in Urban Fringe Area

    National Research Council Canada - National Science Library

    Batara Surya

    2016-01-01

      The study aims at analyzing change of spatial physical, spatial articulation, spatial structure, social and agglomeration and deagglomeration of function in the dynamics of development in the fringe...

  8. Critical domain-wall dynamics of model B.

    Science.gov (United States)

    Dong, R H; Zheng, B; Zhou, N J

    2009-05-01

    With Monte Carlo methods, we simulate the critical domain-wall dynamics of model B, taking the two-dimensional Ising model as an example. In the macroscopic short-time regime, a dynamic scaling form is revealed. Due to the existence of the quasirandom walkers, the magnetization shows intrinsic dependence on the lattice size L . An exponent which governs the L dependence of the magnetization is measured to be sigma=0.243(8) .

  9. SSBD: a database of quantitative data of spatiotemporal dynamics of biological phenomena.

    Science.gov (United States)

    Tohsato, Yukako; Ho, Kenneth H L; Kyoda, Koji; Onami, Shuichi

    2016-11-15

    Rapid advances in live-cell imaging analysis and mathematical modeling have produced a large amount of quantitative data on spatiotemporal dynamics of biological objects ranging from molecules to organisms. There is now a crucial need to bring these large amounts of quantitative biological dynamics data together centrally in a coherent and systematic manner. This will facilitate the reuse of this data for further analysis. We have developed the Systems Science of Biological Dynamics database (SSBD) to store and share quantitative biological dynamics data. SSBD currently provides 311 sets of quantitative data for single molecules, nuclei and whole organisms in a wide variety of model organisms from Escherichia coli to Mus musculus The data are provided in Biological Dynamics Markup Language format and also through a REST API. In addition, SSBD provides 188 sets of time-lapse microscopy images from which the quantitative data were obtained and software tools for data visualization and analysis. SSBD is accessible at http://ssbd.qbic.riken.jp CONTACT: sonami@riken.jp. © The Author 2016. Published by Oxford University Press.

  10. The dynamic aspects of thermo-elasto-viscoplastic snap-through and creep buckling phenomena

    Science.gov (United States)

    Riff, R.; Simitses, G. J.

    1987-01-01

    Use of a mathematical model and solution methodology, to examine dynamic buckling and dynamic postbuckling behavior of shallow arches and spherical caps made of a realistic material and undergoing non-isothermal, elasto-viscoplastic deformation was examined. Thus, geometric as well as material type nonlinearities of higher order are included in this analysis. The dynamic stability problem is studied under impulsive loading and suddenly applied loading with loads of constant magnitude and infinite duration. A finite element model was derived directly from the incrementally formulated nonlinear shell equations, by using a tensor-oriented procedure. As an example of the results, the time history of the midspan displacement of a damped shallow circular arch is presented.

  11. Entanglement dynamics in critical random quantum Ising chain with perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yichen, E-mail: ychuang@caltech.edu

    2017-05-15

    We simulate the entanglement dynamics in a critical random quantum Ising chain with generic perturbations using the time-evolving block decimation algorithm. Starting from a product state, we observe super-logarithmic growth of entanglement entropy with time. The numerical result is consistent with the analytical prediction of Vosk and Altman using a real-space renormalization group technique. - Highlights: • We study the dynamical quantum phase transition between many-body localized phases. • We simulate the dynamics of a very long random spin chain with matrix product states. • We observe numerically super-logarithmic growth of entanglement entropy with time.

  12. Homodyne full-field interferometer for measuring dynamic surface phenomena in microstructures

    Science.gov (United States)

    Lipiäinen, Lauri; Kokkonen, Kimmo; Kaivola, Matti

    2017-01-01

    We describe a stabilized homodyne full-field interferometer capable of measuring vertical surface deformations of microstructures in the time domain. The interferometer is stabilized to a chosen operation point by obtaining a feedback signal from a non-moving, freely selectable, reference region on the sample surface. The stabilized full-field interferometer enables detection of time-dependent changes in the surface profile with nanometer scale vertical resolution, while the temporal resolution of the measurement is ultimately limited by the refresh rate of the camera only. The lateral resolution of the surface deformation is determined by the combination of the imaging optics together with the pixel size of the camera. The setup is used to measure the deformation of an Aluminum nitride membrane as a function of time-dependent pressure change. The data analysis allows for unambiguous determination of surface deformations over multiple fringes of the interferogram, hence enabling the study of a wide range of physical phenomena with varying magnitude of vertical surface movement.

  13. BETAview: a digital {beta}-imaging system for dynamic studies of biological phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bertolucci, E.; Conti, M.; Mettivier, G.; Montesi, M.C. E-mail: montesi@na.infn.it; Russo, P

    2002-02-01

    We present a digital autoradiography (DAR) system, named BETAview, based on semiconductor pixel detectors and a single particle counting chip, for quantitative analysis of {beta}-emitting radioactive tracers in biological samples. The system is able to perform a real time monitoring of time-dependent biological phenomena. BETAview could be equipped either with GaAs or with Si semiconductor pixellated detectors. In this paper, we describe the results obtained with an assembly based on a Si detector, 300 {mu}m thick, segmented into 64x64 170 {mu}m size square pixels. The detector is bump-bonded to the low threshold, single particle counting chip named Medipix1, developed by a CERN-based European collaboration. The sensitive area is about 1 cm{sup 2}. Studies of background noise and detection efficiency have been performed. Moreover, time-resolved cellular uptake studies with radiolabelled molecules have been monitored. Specifically, we have followed in vivo and in real time, the [{sup 14}C]L-leucine amino acid uptake by eggs of Octopus vulgaris confirming the preliminary results of a previous paper. This opens the field of biomolecular kynetic studies with this new class of semiconductor DAR systems, whose evolution (using the Medipix2 chip, 256x256 pixels, 55 {mu}m pixel size) is soon to come.

  14. Critical velocity and dynamic respondency of pipe conveying fluid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Presents the calculation of critical velocity, natural frequencyand dynamic respondency of fluid-conveying pipe are calculated under different boundary conditions using finite element method, and the use of calculation results to design and research rocket pipes feeding fuel and watery turbine pipes conveying water etc.

  15. Entanglement dynamics in critical random quantum Ising chain with perturbations

    Science.gov (United States)

    Huang, Yichen

    2017-05-01

    We simulate the entanglement dynamics in a critical random quantum Ising chain with generic perturbations using the time-evolving block decimation algorithm. Starting from a product state, we observe super-logarithmic growth of entanglement entropy with time. The numerical result is consistent with the analytical prediction of Vosk and Altman using a real-space renormalization group technique.

  16. Dynamics of critical internet culture (1994-2001)

    NARCIS (Netherlands)

    G. Lovink

    2009-01-01

    This study examines the dynamics of critical Internet culture after the medium opened to a broader audience in the mid 1990s. The core of the research consists of four case studies of nonprofit networks: the Amsterdam community provider, The Digital City (DDS); the early years of the nettime mailing

  17. Interfacial phenomena and dynamic contact angle modulation in microcapillary flows subjected to electroosmotic actuation.

    Science.gov (United States)

    Chakraborty, Debapriya; Chakraborty, Suman

    2008-09-02

    The dynamic evolution of an incompressible liquid meniscus inside a microcapillary is investigated, under the combined influences of viscous, capillary, intermolecular, pondermotive, and electroosmotic effects. In the limit of small capillary numbers, an advancing meniscus shape is shown to merge smoothly with the precursor film, using matched asymptotic analysis. A scaling relationship is also established for the dynamic contact angle as a nondimensional function of the capillary number and the applied electrical voltage. The analysis is further generalized by invoking a kinetic slip model for overcoming the constraints of meniscus tip singularity. The kinetic slip model is subsequently utilized to analyze the interfacial dynamics from the perspective of the results obtained from the matched asymptotic analysis. A generalization is achieved in this regard, which may provide a sound basis for controlling the topographical features of a dynamically evolving meniscus in a microcapillary subjected to electrokinetic effects. These results are also in excellent agreement with the experimental findings over a wide range of capillary number values.

  18. Critical dynamics on a large human Open Connectome network

    Science.gov (United States)

    Ódor, Géza

    2016-12-01

    Extended numerical simulations of threshold models have been performed on a human brain network with N =836 733 connected nodes available from the Open Connectome Project. While in the case of simple threshold models a sharp discontinuous phase transition without any critical dynamics arises, variable threshold models exhibit extended power-law scaling regions. This is attributed to fact that Griffiths effects, stemming from the topological or interaction heterogeneity of the network, can become relevant if the input sensitivity of nodes is equalized. I have studied the effects of link directness, as well as the consequence of inhibitory connections. Nonuniversal power-law avalanche size and time distributions have been found with exponents agreeing with the values obtained in electrode experiments of the human brain. The dynamical critical region occurs in an extended control parameter space without the assumption of self-organized criticality.

  19. Optimal Dynamical Range of Excitable Networks at Criticality

    CERN Document Server

    Kinouchi, Osame

    2006-01-01

    A recurrent idea in the study of complex systems is that optimal information processing is to be found near bifurcation points or phase transitions. However, this heuristic hypothesis has few (if any) concrete realizations where a standard and biologically relevant quantity is optimized at criticality. Here we give a clear example of such a phenomenon: a network of excitable elements has its sensitivity and dynamic range maximized at the critical point of a non-equilibrium phase transition. Our results are compatible with the essential role of gap junctions in olfactory glomeruli and retinal ganglionar cell output. Synchronization and global oscillations also appear in the network dynamics. We propose that the main functional role of electrical coupling is to provide an enhancement of dynamic range, therefore allowing the coding of information spanning several orders of magnitude. The mechanism could provide a microscopic neural basis for psychophysical laws.

  20. Dynamical indicators for the prediction of bursting phenomena in high-dimensional systems

    CERN Document Server

    Farazmand, Mohammad

    2016-01-01

    Drawing upon the bursting mechanism in slow-fast systems, we propose indicators for the prediction of such rare extreme events which do not require a priori known slow and fast coordinates. The indicators are associated with functionals defined in terms of Optimally Time Dependent (OTD) modes. One such functional has the form of the largest eigenvalue of the symmetric part of the linearized dynamics reduced to these modes. In contrast to other choices of subspaces, the proposed modes are flow invariant and therefore a projection onto them is dynamically meaningful. We illustrate the application of these indicators on three examples: a prototype low-dimensional model, a body forced turbulent fluid flow, and a unidirectional model of nonlinear water waves. We use Bayesian statistics to quantify the predictive power of the proposed indicators.

  1. Facilitation Dynamics and Localization Phenomena in Rydberg Lattice Gases with Position Disorder

    Science.gov (United States)

    Marcuzzi, Matteo; Minář, Jiří; Barredo, Daniel; de Léséleuc, Sylvain; Labuhn, Henning; Lahaye, Thierry; Browaeys, Antoine; Levi, Emanuele; Lesanovsky, Igor

    2017-02-01

    We explore the dynamics of Rydberg excitations in an optical tweezer array under antiblockade (or facilitation) conditions. Because of the finite temperature the atomic positions are randomly spread, an effect that leads to quenched correlated disorder in the interatomic interaction strengths. This drastically affects the facilitation dynamics as we demonstrate experimentally on the elementary example of two atoms. To shed light on the role of disorder in a many-body setting we show that here the dynamics is governed by an Anderson-Fock model, i.e., an Anderson model formulated on a lattice with sites corresponding to many-body Fock states. We first consider a one-dimensional atom chain in a limit that is described by a one-dimensional Anderson-Fock model with disorder on every other site, featuring both localized and delocalized states. We then illustrate the effect of disorder experimentally in a situation in which the system maps on a two-dimensional Anderson-Fock model on a trimmed square lattice. We observe a clear suppression of excitation propagation, which we ascribe to the localization of the many-body wave functions in Hilbert space.

  2. Critical dynamics of a nonlocal model and critical behavior of perovskite manganites.

    Science.gov (United States)

    Singh, Rohit; Dutta, Kishore; Nandy, Malay K

    2016-05-01

    We investigate the nonconserved critical dynamics of a nonlocal model Hamiltonian incorporating screened long-range interactions in the quartic term. Employing dynamic renormalization group analysis at one-loop order, we calculate the dynamic critical exponent z=2+εf_{1}(σ,κ,n)+O(ε^{2}) and the linewidth exponent w=-σ+εf_{2}(σ,κ,n)+O(ε^{2}) in the leading order of ε, where ε=4-d+2σ, with d the space dimension, n the number of components in the order parameter, and σ and κ the parameters coming from the nonlocal interaction term. The resulting values of linewidth exponent w for a wide range of σ is found to be in good agreement with the existing experimental estimates from spin relaxation measurements in perovskite manganite samples.

  3. Dynamics of fragments and associated phenomena in heavy-ion collisions using a modified secondary algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rohit [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2016-05-06

    We discuss the stability of fragments identified by secondary algorithms used to construct fragments within quantum molecular dynamics model. For this purpose we employ three different algorithms for fragment identification. 1) The conventional minimum spanning tree (MST) method based on the spatial correlations, 2) an improved version of MST with additional binding energy constraints of cold nuclear matter, 3) and that of hot matter. We find significant role of thermal binding energies over cold matter binding energies. Significant role is observed for fragment multiplicities and stopping of fragments. Whereas insignificant effect is observed on fragment’s flow.

  4. Static and dynamic properties of critical fluctuations in lipid bilayers

    Science.gov (United States)

    Honerkamp-Smith, Aurelia Rose

    A current popular view in cell biology is that sub-micron, dynamic heterogeneity in lipid and protein composition arises within the plasma membranes of resting cells. Local changes in membrane composition may affect protein activity, which is sensitive to the lipid environment. We have observed dynamic heterogeneity in lipid membranes in the form of composition fluctuations near a miscibility critical point. In this thesis we quantitatively describe the dynamic and static properties of these fluctuations. We evaluate the temperature dependence of line tension between liquid domains and of fluctuation correlation lengths in lipid membranes in order to extract a critical exponent, nu. We obtain nu = 1.2 +/- 0.2, consistent with the Ising model prediction nu = 1. From probability distributions of pixel intensities in fluorescence images of membranes, we also extract an independent critical exponent of beta = 0.124 +/- 0.03, which is consistent with the Ising prediction of beta = 1/8. We have systematically measured the effective dynamic critical exponent z eff in a lipid membrane while cooling the system toward a critical point. We observe that zeff slightly increases from a value of roughly 2.6 as xi → 0, to zeff = 3.0 +/- 0.15 at xi = 13 sm. Our measurements are consistent with the prediction that zeff → 3.00 as T → Tc for a 2-D system with conserved order parameter in contact with a bulk 3-D liquid. To our knowledge, no other systematic measurement of zeff with increasing xi exists for a 2-D system with conserved order parameter. We also report the solubility limit of several biologically relevant sterols in electroformed giant unilamellar vesicle membranes containing phosphatidylcholine (PC) lipids in ratios of 1:1:X DPPC:DOPC:sterol. We find solubility limits of cholesterol, lanosterol, ergosterol, stigmasterol, and beta-sitosterol using nuclear magnetic resonance.

  5. Critical dynamics in genetic regulatory networks: examples from four kingdoms.

    Science.gov (United States)

    Balleza, Enrique; Alvarez-Buylla, Elena R; Chaos, Alvaro; Kauffman, Stuart; Shmulevich, Ilya; Aldana, Maximino

    2008-06-18

    The coordinated expression of the different genes in an organism is essential to sustain functionality under the random external perturbations to which the organism might be subjected. To cope with such external variability, the global dynamics of the genetic network must possess two central properties. (a) It must be robust enough as to guarantee stability under a broad range of external conditions, and (b) it must be flexible enough to recognize and integrate specific external signals that may help the organism to change and adapt to different environments. This compromise between robustness and adaptability has been observed in dynamical systems operating at the brink of a phase transition between order and chaos. Such systems are termed critical. Thus, criticality, a precise, measurable, and well characterized property of dynamical systems, makes it possible for robustness and adaptability to coexist in living organisms. In this work we investigate the dynamical properties of the gene transcription networks reported for S. cerevisiae, E. coli, and B. subtilis, as well as the network of segment polarity genes of D. melanogaster, and the network of flower development of A. thaliana. We use hundreds of microarray experiments to infer the nature of the regulatory interactions among genes, and implement these data into the Boolean models of the genetic networks. Our results show that, to the best of the current experimental data available, the five networks under study indeed operate close to criticality. The generality of this result suggests that criticality at the genetic level might constitute a fundamental evolutionary mechanism that generates the great diversity of dynamically robust living forms that we observe around us.

  6. In situ monitoring of dynamic bounce phenomena in RF MEMS switches

    Science.gov (United States)

    Fruehling, Adam; Tung, Ryan; Raman, Arvind; Peroulis, Dimitrios

    2013-11-01

    This paper presents the first ultra-low-power complementary metal-oxide-semiconductor (CMOS)-based measurement technique for monitoring the cold-switched dynamic behavior of ohmic radiofrequency microelectromechanical systems (RF MEMS) switches in real time. The circuit is capable of providing precise information about contact timing and ohmic contact events. Sampling of dynamic events at frequencies of 1 and 5 MHz shows contact timing accuracy of 99% when compared with real-time true-height information obtained from laser Doppler vibration data. The technique is validated for an ohmic RF MEMS switch with multiple bounces. The actuation voltage has also been designed to enhance bouncing behavior to more clearly study the performance and limits of the presented technique. More than 13 bounces are successfully captured by the electronic measurement technique. The weakest bounces exhibit vertical displacements of less than 20 nm as recorded by a laser Doppler vibrometer. This demonstrates the ability to capture precise timing information even for weak contacting events. A detailed discussion of how parasitics influence this technique is also presented for the first time.

  7. How far can a pragmatist go into quantum theory? - A critical view of our current understanding of quantum phenomena

    CERN Document Server

    Sanz, A S

    2015-01-01

    To date, quantum mechanics has proven to be our most successful theoretical model. However, it is still surrounded by a "mysterious halo" that can be summarized in a simple but challenging question: Why quantum phenomena are not understood under the same logic as classical ones? Although this is an open question (probably without an answer), from a pragmatist's point of view there is still room enough to further explore the quantum world, marveling ourselves with new physical insights. We just need to look back in the historical evolution of the quantum theory and thoroughly reconsider three key issues: (1) how this has developed since its early stages at a conceptual level, (2) what kind of experiments can be performed at present in a laboratory, and (3) what nonstandard conceptual models are available to extract some extra information. This contribution is aimed at providing some answers (and, perhaps, also raising some issues) to these questions through one of such models, namely Bohmian mechanics, a hydro...

  8. The complex dynamics of wishful thinking: The critical positivity ratio

    CERN Document Server

    Brown, Nicholas J L; Friedman, Harris L

    2013-01-01

    We examine critically the claims made by Fredrickson and Losada (2005) concerning the construct known as the "positivity ratio". We find no theoretical or empirical justification for the use of differential equations drawn from fluid dynamics, a subfield of physics, to describe changes in human emotions over time; furthermore, we demonstrate that the purported application of these equations contains numerous fundamental conceptual and mathematical errors. The lack of relevance of these equations and their incorrect application lead us to conclude that Fredrickson and Losada's claim to have demonstrated the existence of a critical minimum positivity ratio of 2.9013 is entirely unfounded. More generally, we urge future researchers to exercise caution in the use of advanced mathematical tools such as nonlinear dynamics and in particular to verify that the elementary conditions for their valid application have been met.

  9. A Investigation of Dynamic Laser Speckle Phenomena Using Photon Limited Detection

    Science.gov (United States)

    Newman, Jeffrey Daniel

    The statistical properties of dynamic laser speckle patterns are investigated in theory and in experiment using photon limited pulse counting techniques. The primary analytic tool for these investigations is the spatio-temporal correlation of intensity fluctuations which is shown to yield detailed structural information about the source intensity distribution behind the scatterer and the scattering plane motion. It is demonstrated that the intensity correlation structure of fluctuating optical fields can be measured simultaneously in the spatial and temporal domains using a two dimensional imaging photodetector (IPD) and time marking electronics. Preliminary measurements with this device show that the method is well suited for use in a variety of practical measurement schemes including speckle velocimetry and stellar speckle interferometry. The present configuration relies on a software based delayed coincidence counter which is approximately 200 time too slow to keep up with the data in real time. The total data base is limited to 5 x 10('4) detected photoevents from which the correlation function is estimated at over 2 x 10('3) space -time lags with a signal to noise ratio of 15:1. The practical limitations associated with IPD correlation measurements are discussed in detail. The properties of dynamic speckle from pseudo -random scattering surfaces, which contains both random and non-random phase structures are investigated. It is shown in the special case of a phase grating placed behind a diffuser that the grating structure may be uniquely recovered from both spatial and temporal intensity correlation measurements of the scattered light. In particular, the temporal autocorrelation measurements are shown to reveal the grating structure under conditions of arbitrarily diffuse scattering, e.g. when there is no visual indication of the grating's presence in the diffraction pattern. The possible use of these results for a commercial optical information coding scheme

  10. Sensitivity analysis of the critical speed in railway vehicle dynamics

    Science.gov (United States)

    Bigoni, D.; True, H.; Engsig-Karup, A. P.

    2014-05-01

    We present an approach to global sensitivity analysis aiming at the reduction of its computational cost without compromising the results. The method is based on sampling methods, cubature rules, high-dimensional model representation and total sensitivity indices. It is applied to a half car with a two-axle Cooperrider bogie, in order to study the sensitivity of the critical speed with respect to the suspension parameters. The importance of a certain suspension component is expressed by the variance in critical speed that is ascribable to it. This proves to be useful in the identification of parameters for which the accuracy of their values is critically important. The approach has a general applicability in many engineering fields and does not require the knowledge of the particular solver of the dynamical system. This analysis can be used as part of the virtual homologation procedure and to help engineers during the design phase of complex systems.

  11. Light Bridge in a Developing Active Region. I. Observation of Light Bridge and its Dynamic Activity Phenomena

    CERN Document Server

    Toriumi, Shin; Cheung, Mark C M

    2015-01-01

    Light bridges, the bright structures that divide the umbra of sunspots and pores into smaller pieces, are known to produce wide variety of activity events in solar active regions (ARs). It is also known that the light bridges appear in the assembling process of nascent sunspots. The ultimate goal of this series of papers is to reveal the nature of light bridges in developing ARs and the occurrence of activity events associated with the light bridge structures from both observational and numerical approaches. In this first paper, exploiting the observational data obtained by Hinode, IRIS, and Solar Dynamics Observatory (SDO), we investigate the detailed structure of the light bridge in NOAA AR 11974 and its dynamic activity phenomena. As a result, we find that the light bridge has a weak, horizontal magnetic field, which is transported from the interior by large-scale convective upflow and is surrounded by strong, vertical fields of adjacent pores. In the chromosphere above the bridge, a transient brightening ...

  12. Cell Mechanics From cytoskeletal dynamics to tissue-scale mechanical phenomena

    Science.gov (United States)

    Banerjee, Shiladitya

    This dissertation explores the mechanics of living cells, integrating the role of intracellular activity to capture the emergent mechanical behavior of cells. The topics covered in this dissertation fall into three broad categories : (a) intracellular mechanics, (b) interaction of cells with the extracellular matrix and (c) collective mechanics of multicellular colonies. In part (a) I propose theoretical models for motor-filament interactions in the cell cytoskeleton, which is the site for mechanical force generation in cells. The models predict in a unified manner how contractility, dynamic instabilities and mechanical waves arise in the cytoskeleton by tuning the activity of molecular motors. The results presented in (a) holds relevance to a variety of cellular systems that behave elastically at long time scales, such as muscle sarcomeres, actomyosin stress fibers, adherent cells. In part (b) I introduce a continuum mechanical model for cells adherent to two-dimensional extracellular matrix, and discuss how cells can sense mechanical and geometrical cues from its surrounding matrix. The model provides an important step towards a unified theoretical description of the dependence of traction forces on cell size, actomyosin activity, matrix depth and stiffness, strength of focal adhesions and makes experimentally testable predictions. In part (c) we combine experiment and theory to reveal how intercellular adhesions modulate forces transmitted to the extracellular matrix. We find that In the absence of cadherin-based adhesions, cells within a colony appear to act independently, whereas with strong cadherin-based adhesions, the cell colony behaves like a liquid droplet wetting the substrate underneath. This work defines the importance of intercellular adhesions in coordinating mechanical activity of cell monolayers and has implications for the mechanical regulation of tissues during development, homeostasis, and disease.

  13. Steady-state observations and theoretical modeling of critical heat flux phenomena on a downward facing hemispherical surface

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, F.B.; Haddad, K.H. [Pennsylvania State Univ., University Park, PA (United States)

    1996-03-01

    Steady-state boiling experiments were performed in the SBLB test facility to observe the two-phase boundary layer flow behavior on the outer surface of a heated hemispherical vessel near the critical heat flux (CHF) limit and to measure the spatial variation of the local CHF along the vessel outer surface. Based upon the flow observations, an advanced hydrodynamic CHF model was developed. The model considers the existence of a micro-layer underneath an elongated vapor slug on the downward facing curved heating surface. The micro-layer is treated as a thin liquid film with numerous micro-vapor jets penetrating through it. The micro-jets have the characteristic size dictated by Helmholtz instability. Local dryout is considered to occur when the supply of fresh liquid from the two phase boundary layer to the micro-layer is not sufficient to prevent depletion of the liquid film by boiling. A boundary layer analysis, treating the two-phase motion as a separated flow, is performed to determine the liquid supply rate and thus the local critical heat flux. The model provides a clear physical explanation for the spatial variation of the CHF observed in the SBLB experiments and for the weak dependence of the CHF data on the physical size of the vessel.

  14. Critical Heat Flux Phenomena at HighPressure & Low Mass Fluxes: NEUP Final Report Part I: Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Corradini, Michael [Univ. of Wisconsin, Madison, WI (United States); Wu, Qiao [Oregon State Univ., Corvallis, OR (United States)

    2015-04-30

    This report is a preliminary document presenting an overview of the Critical Heat Flux (CHF) phenomenon, the High Pressure Critical Heat Flux facility (HPCHF), preliminary CHF data acquired, and the future direction of the research. The HPCHF facility has been designed and built to study CHF at high pressure and low mass flux ranges in a rod bundle prototypical of conceptual Small Modular Reactor (SMR) designs. The rod bundle is comprised of four electrically heated rods in a 2x2 square rod bundle with a prototypic chopped-cosine axial power profile and equipped with thermocouples at various axial and circumferential positions embedded in each rod for CHF detection. Experimental test parameters for CHF detection range from pressures of ~80 – 160 bar, mass fluxes of ~400 – 1500 kg/m2s, and inlet water subcooling from ~30 – 70°C. The preliminary data base established will be further extended in the future along with comparisons to existing CHF correlations, models, etc. whose application ranges may be applicable to the conditions of SMRs.

  15. Tunable Optical Phenomena and Carrier Recombination Dynamics in III-V Semiconductor Nanostructures

    Science.gov (United States)

    Kumar Thota, Venkata Ramana

    . The results are presented in chapter 6. Finally, carrier recombination dynamics in rare-earth doped nanostructures are measured by using ultrafast spectroscopy. Carrier dynamics in InGaN:Yb 3+ nanowires and InGaN/GaN-Eu3+ superlattices are measured by frequency doubling the excitation laser, and the effects of implantation of rare-earth ions into the host material have been investigated. The results from the experimental measurements are presented in chapters 7 & 8. These experimental findings might help to understand the challenges associated with these nanostructured materials in the applications of quantum information processing, single photon emitters, and to integrate them into existing optoelectronic devices.

  16. Dynamic relaxation processes in compressible multiphase flows. Application to evaporation phenomena

    Directory of Open Access Journals (Sweden)

    Le Métayer O.

    2013-07-01

    Full Text Available Phase changes and heat exchanges are examples of physical processes appearing in many industrial applications involving multiphase compressible flows. Their knowledge is of fundamental importance to reproduce correctly the resulting effects in simulation tools. A fine description of the flow topology is thus required to obtain the interfacial area between phases. This one is responsible for the dynamics and the kinetics of heat and mass transfer when evaporation or condensation occurs. Unfortunately this exchange area cannot be obtained easily and accurately especially when complex mixtures (drops, bubbles, pockets of very different sizes appear inside the transient medium. The natural way to solve this specific trouble consists in using a thin grid to capture interfaces at all spatial scales. But this possibility needs huge computing resources and can be hardly used when considering physical systems of large dimensions. A realistic method is to consider instantaneous exchanges between phases by the way of additional source terms in a full non-equilibrium multiphase flow model [2,15,17]. In this one each phase obeys its own equation of state and has its own set of equations and variables (pressure, temperature, velocity, energy, entropy,.... When enabling the relaxation source terms the multiphase mixture instantaneously tends towards a mechanical or thermodynamic equilibrium state at each point of the flow. This strategy allows to mark the boundaries of the real flow behavior and to magnify the dominant physical effects (heat exchanges, evaporation, drag,... inside the medium. A description of the various relaxation processes is given in the paper. Les changements de phase et les transferts de chaleur sont des exemples de phénomènes physiques présents dans de nombreuses applications industrielles faisant intervenir des écoulements compressibles multiphasiques. La connaissance des mécanismes associés est primordiale afin de reproduire

  17. Nonequilibrium critical dynamics of two dimensional interacting monomer-dimer model: non-Ising criticality

    Science.gov (United States)

    Nam, Keekwon; Kim, Bongsoo; Jong Lee, Sung

    2014-08-01

    We investigate the nonequilibrium relaxation dynamics of an interacting monomer-dimer model with nearest neighbor repulsion on a square lattice, which possesses two symmetric absorbing states. The model is known to exhibit two nearby continuous transitions: the Z2 symmetry-breaking order-disorder transition and the absorbing transition with directed percolation criticality. We performed a more detailed analysis of our extensive simulations on bigger lattice systems which reaffirms that the symmetry-breaking transition exhibits a non-Ising critical behavior with β ≃ 0.149(2) and η ≃ 0.30(1) that are distinct from those values of a pure two dimensional Ising model. Finite size scaling of dimer density near the symmetry breaking transition gives logarithmic scaling (α = 0.0) which is consistent with the hyperscaling relation but the corresponding exponent of νB ≃ 1.37(2) exhibits a conspicuous deviation from the pure Ising value of 1. The value of dynamic critical exponent z, however, is found to be close to that of the kinetic Ising model as 1/z ≃ 0.466(5) from the relaxation of staggered magnetization (and also similar but slightly smaller values from coarsening).

  18. Network Randomization and Dynamic Defense for Critical Infrastructure Systems

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Adrian R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Mitchell Tyler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hamlet, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stout, William M.S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Erik [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-04-01

    Critical Infrastructure control systems continue to foster predictable communication paths, static configurations, and unpatched systems that allow easy access to our nation's most critical assets. This makes them attractive targets for cyber intrusion. We seek to address these attack vectors by automatically randomizing network settings, randomizing applications on the end devices themselves, and dynamically defending these systems against active attacks. Applying these protective measures will convert control systems into moving targets that proactively defend themselves against attack. Sandia National Laboratories has led this effort by gathering operational and technical requirements from Tennessee Valley Authority (TVA) and performing research and development to create a proof-of-concept solution. Our proof-of-concept has been tested in a laboratory environment with over 300 nodes. The vision of this project is to enhance control system security by converting existing control systems into moving targets and building these security measures into future systems while meeting the unique constraints that control systems face.

  19. Transport Phenomena.

    Science.gov (United States)

    Shah, D. B.

    1984-01-01

    Describes a course designed to achieve a balance between exposing students to (1) advanced topics in transport phenomena, pointing out similarities and differences between three transfer processes and (2) common methods of solving differential equations. (JN)

  20. Dynamic nature at the QCD Critical End Point

    CERN Document Server

    Ohnishi, K; Ohnishi, Kazuaki; Teiji Kunihiro

    2005-01-01

    We discuss the dynamic nature of the critical end point (CEP) which is the end point of the first order chiral phase transition. In the earlier work, Son and Stephanov analyzed the Langevin equation for CEP taking care of the mixing effect between the chiral condensate and the baryon number density and showed that the dynamic universality class of CEP is the model H, the same as that of the end point of the liquid-gas transition. We point out a difficulty in their treatment that the theory does not correctly reduce to CEP in the limiting situation where the mixing effect disappears. We give a reanalysis of the Langevin equation to conclude that CEP belongs to the model C apart from the energy and momentum densities, which is the same conclusion as given by Berdnikov and Rajagopal. We also propose a new signal for CEP in the heavy-ion collision experiments.

  1. Critical bifurcation surfaces of 3D discrete dynamics

    Directory of Open Access Journals (Sweden)

    Michael Sonis

    2000-01-01

    Full Text Available This paper deals with the analytical representation of bifurcations of each 3D discrete dynamics depending on the set of bifurcation parameters. The procedure of bifurcation analysis proposed in this paper represents the 3D elaboration and specification of the general algorithm of the n-dimensional linear bifurcation analysis proposed by the author earlier. It is proven that 3D domain of asymptotic stability (attraction of the fixed point for a given 3D discrete dynamics is bounded by three critical bifurcation surfaces: the divergence, flip and flutter surfaces. The analytical construction of these surfaces is achieved with the help of classical Routh–Hurvitz conditions of asymptotic stability. As an application the adjustment process proposed by T. Puu for the Cournot oligopoly model is considered in detail.

  2. Complex ordering in spin networks: Critical role of adaptation rate for dynamically evolving interactions

    Science.gov (United States)

    Pathak, Anand; Sinha, Sitabhra

    2015-09-01

    Many complex systems can be represented as networks of dynamical elements whose states evolve in response to interactions with neighboring elements, noise and external stimuli. The collective behavior of such systems can exhibit remarkable ordering phenomena such as chimera order corresponding to coexistence of ordered and disordered regions. Often, the interactions in such systems can also evolve over time responding to changes in the dynamical states of the elements. Link adaptation inspired by Hebbian learning, the dominant paradigm for neuronal plasticity, has been earlier shown to result in structural balance by removing any initial frustration in a system that arises through conflicting interactions. Here we show that the rate of the adaptive dynamics for the interactions is crucial in deciding the emergence of different ordering behavior (including chimera) and frustration in networks of Ising spins. In particular, we observe that small changes in the link adaptation rate about a critical value result in the system exhibiting radically different energy landscapes, viz., smooth landscape corresponding to balanced systems seen for fast learning, and rugged landscapes corresponding to frustrated systems seen for slow learning.

  3. General Critical Properties of the Dynamics of Scientific Discovery

    Energy Technology Data Exchange (ETDEWEB)

    Bettencourt, L. M. A. (LANL); Kaiser, D. I. (MIT)

    2011-05-31

    Scientific fields are difficult to define and compare, yet there is a general sense that they undergo similar stages of development. From this point of view it becomes important to determine if these superficial similarities can be translated into a general framework that would quantify the general advent and subsequent dynamics of scientific ideas. Such a framework would have important practical applications of allowing us to compare fields that superficially may appear different, in terms of their subject matter, research techniques, typical collaboration size, etc. Particularh' important in a field's history is the moment at which conceptual and technical unification allows widespread exchange of ideas and collaboration, at which point networks of collaboration show the analog of a percolation phenomenon, developing a giant connected component containing most authors. Here we investigate the generality of this topological transition in the collaboration structure of scientific fields as they grow and become denser. We develop a general theoretical framework in which each scientific field is an instantiation of the same large-scale topological critical phenomenon. We consider whether the evidence from a variety of specific fields is consistent with this picture, and estimate critical exponents associated with the transition. We then discuss the generality of the phenomenon and to what extent we may expect other scientific fields — including very large ones — to follow the same dynamics.

  4. Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

    Directory of Open Access Journals (Sweden)

    N. F. Blagoveshchenskaya

    2009-01-01

    Full Text Available Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency fH was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ. The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the London-Tromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland, the European Incoherent Scatter (EISCAT UHF radar at Tromsø and the Tromsø ionosonde (dynasonde. The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization.

  5. Size and diffusion phenomena of AOT/alcohol/water system in the presence of morin by dynamic light scattering.

    Science.gov (United States)

    Bhattarai, Ajaya; Wilczura-Wachnik, Hanna

    2015-01-30

    Presented paper is a continuation of our studies on morin interaction with AOT (sodium bis(2-ethylhexyl) sulfosuccinate) reversed micelles solutions in two solvents: ethanol and n-decanol. Now we focused on morin influence on size and diffusion phenomena in the system morin/solvent/AOT/water. In this paper precise measurements of dynamic light scattering (DLS) of the effects of temperature, solvents (alcohols), water on the size and diffusion of AOT reversed micelles in the morin/AOT/alcohol/water system are reported. The concentrations of AOT were varied from 0.51 to 0.78mol/L. Morin concentration in during auto-correlation function registration was not the same in each solvent because of its different solubility depending on the solvent. Water concentration in the studied systems was defined by R parameter according to relation: R=(H2O)/(AOT) and was equal 0 and 30 in ethanol, and 0 in n-decanol. DLS measurements were done at 298.15 and 308.15K. DLS experiment involved on detection two relaxation modes (fast and slow) in the systems containing AOT reversed micelles, water, morin and solvents (ethanol and n-decanol). The DLS data clearly show the solvent influence as well as morin presence on AOT reversed micelles size and consequently their diffusion coefficients. Contrary to n-decanol strong competition between morin and ethanol molecules in AOT reversed micelles palisade layer has been found. It suggests that morin molecules replaced ethanol in AOT reversed micelles and locate in their palisade layer strongly increasing AOT reversed micelles size. Furthermore, it was found a sharp increase in correlation radii of slow modes of AOT reversed micelles containing morin molecules and their diffusion coefficients diminishing.

  6. Information processing and integration with intracellular dynamics near critical point.

    Science.gov (United States)

    Kamimura, Atsushi; Kobayashi, Tetsuya J

    2012-01-01

    Recent experimental observations suggest that cells can show relatively precise and reliable responses to external signals even though substantial noise is inevitably involved in the signals. An intriguing question is the way how cells can manage to do it. One possible way to realize such response for a cell is to evolutionary develop and optimize its intracellular signaling pathways so as to extract relevant information from the noisy signal. We recently demonstrated that certain intracellular signaling reactions could actually conduct statistically optimal information processing. In this paper, we clarify that such optimal reaction operates near bifurcation point. This result suggests that critical-like phenomena in the single-cell level may be linked to efficient information processing inside a cell. In addition, improving the performance of response in the single-cell level is not the only way for cells to realize reliable response. Another possible strategy is to integrate information of individual cells by cell-to-cell interaction such as quorum sensing. Since cell-to-cell interaction is a common phenomenon, it is equally important to investigate how cells can integrate their information by cell-to-cell interaction to realize efficient information processing in the population level. In this paper, we consider roles and benefits of cell-to-cell interaction by considering integrations of obtained information of individuals with the other cells from the viewpoint of information processing. We also demonstrate that, by introducing cell movement, spatial organizations can spontaneously emerge as a result of efficient responses of the population to external signals.

  7. Molecular modeling and molecular dynamics simulation of the polarization switching phenomena in the ferroelectric polymers PVDF at the nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Bystrov, V.S., E-mail: bystrov@ua.pt [Department of Materials and Ceramic Engineering and CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Institute of Mathematical Problems of Biology RAS, 142290, Pushchino (Russian Federation)

    2014-01-01

    The molecular modeling and molecular dynamics of polarization switching for the ferroelectric films model of polyvinylidene fluoride (PVDF) are investigated at the nanoscale. We consider a molecular model of PVDF film, consisting of two and four a chains [–CH2–CF2–]{sub n} limited by n=6 elementary units. The first-principle approach is applied to the switching and kinetics of these models. Two types of behavior were established for PVDF chains: simultaneous and sequential rotation in high and low electric fields. Kinetics of sequential polarization switching shows a homogeneous critical behavior in the low electric field with a critical point at Landau–Ginzburg–Devonshire (LGD) coercive field E=E{sub C}. This type of kinetics demonstrates a kink-like behavior for polarization solitary wave propagation. The simultaneous type of kinetics demonstrates the total domain-like polarization switching, corresponding to exponential behavior of switching time in high electric field as for bulk samples. Corresponding LGD intrinsic coercive field for a two-chain and four-chains model is E{sub C}∼2.0 GV/m with revealing size effect. Obtained results show common quantum nature of PVDF chains switching phenomena—the quantum interaction of the PVDF molecular orbitals under applied electric field at the nanoscale level. The results obtained are compared with experimental data.

  8. The Ramifications of Meddling with Systems Governed by Self-organized Critical Dynamics

    Science.gov (United States)

    Carreras, B. A.; Newman, D. E.; Dobson, I.

    2002-12-01

    Complex natural, well as man-made, systems often exhibit characteristics similar to those seen in self-organized critical (SOC) systems. The concept of self-organized criticality brings together ideas of self-organization of nonlinear dynamical systems with the often-observed near critical behavior of many natural phenomena. These phenomena exhibit self-similarities over extended ranges of spatial and temporal scales. In those systems, scale lengths may be described by fractal geometry and time scales that lead to 1/f-like power spectra. Natural applications include modeling the motion of tectonics plates, forest fires, magnetospheric dynamics, spin glass systems, and turbulent transport. In man-made systems, applications have included traffic dynamics, power and communications networks, and financial markets among many others. Simple cellular automata models such as the running sandpile model have been very useful in reproducing the complexity and characteristics of these systems. One characteristic property of the SOC systems is that they relax through what we call events. These events can happen over all scales of the system. Examples of these events are: earthquakes in the case of plate tectonic; fires in forest evolution extinction in the co evolution of biological species; and blackouts in power transmission systems. In a time-averaged sense, these systems are subcritical (that is, they lie in an average state that should not trigger any events) and the relaxation events happen intermittently. The time spent in a subcritical state relative to the time of the events varies from one system to another. For instance, the chance of finding a forest on fire is very low with the frequency of fires being on the order of one fire every few years and with many of these fires small and inconsequential. Very large fires happen over time periods of decades or even centuries. However, because of their consequences, these large but infrequent events are the important ones

  9. Transport Phenomena.

    Science.gov (United States)

    McCready, Mark J.; Leighton, David T.

    1987-01-01

    Discusses the problems created in graduate chemical engineering programs when students enter with a wide diversity of understandings of transport phenomena. Describes a two-semester graduate transport course sequence at the University of Notre Dame which focuses on fluid mechanics and heat and mass transfer. (TW)

  10. Critical dynamics of cluster algorithms in the dilute Ising model

    Science.gov (United States)

    Hennecke, M.; Heyken, U.

    1993-08-01

    Autocorrelation times for thermodynamic quantities at T C are calculated from Monte Carlo simulations of the site-diluted simple cubic Ising model, using the Swendsen-Wang and Wolff cluster algorithms. Our results show that for these algorithms the autocorrelation times decrease when reducing the concentration of magnetic sites from 100% down to 40%. This is of crucial importance when estimating static properties of the model, since the variances of these estimators increase with autocorrelation time. The dynamical critical exponents are calculated for both algorithms, observing pronounced finite-size effects in the energy autocorrelation data for the algorithm of Wolff. We conclude that, when applied to the dilute Ising model, cluster algorithms become even more effective than local algorithms, for which increasing autocorrelation times are expected.

  11. Dynamical eigenfunctions and critical density in loop quantum cosmology

    CERN Document Server

    Craig, David A

    2012-01-01

    We offer a new, physically transparent argument for the existence of the critical, universal maximum matter density in loop quantum cosmology for the case of a flat Friedmann-Lemaitre-Robertson-Walker cosmology with scalar matter. The argument is based on the existence of a sharp exponential ultraviolet cutoff in momentum space on the eigenfunctions of the quantum cosmological dynamical evolution operator (the gravitational part of the Hamiltonian constraint), attributable to the fundamental discreteness of spatial volume in loop quantum cosmology. The existence of the cutoff is proved directly from recently found exact solutions for the eigenfunctions for this model. As a consequence, the operators corresponding to the momentum of the scalar field and the spatial volume approximately commute. The ultraviolet cutoff then implies that the scalar momentum, though not a bounded operator, is in effect bounded on subspaces of constant volume, leading to the upper bound on the expectation value of the matter densit...

  12. Feketeness, equidistribution and critical orbits in non-archimedean dynamics

    CERN Document Server

    Okuyama, Yûsuke

    2011-01-01

    We study quantitatively a dynamically weighted asymptotic Feketeness of pullbacks of points under a rational function of degree $d>1$ on the projective line over a possibly non-archimedean algebraically closed field which is more general than that of complex numbers. As application, we obtain an error estimate of equidistribution of pullbacks of points for continuously differentiable test functions on the Berkovich projective line in terms of the proximity of critical orbits to the initial points, and show that except for a set of initial points of capacity 0 in the postcritical set, the error term of equidistribution of $k$-th pullbacks is estimated by the arithmetic order $O(\\sqrt{kd^{-k}})$.

  13. Experimental investigation of the fluid dynamic efficiency of a high performance multi-valve internal combustion engine during the intake phase: Influence of valve-valve interference phenomena

    Directory of Open Access Journals (Sweden)

    Algieri Angelo

    2013-01-01

    Full Text Available The purpose of the present work is the analysis of the fluid dynamic behavior of a high performance internal combustion engine during the intake phase. In particular, a four-valve spark-ignition engine has been characterized at the steady flow rig. Dimensionless discharge coefficients have been used to define the global fluid dynamic efficiency of the intake system, while the Laser Doppler Anemometry (LDA technique has been employed to evaluate the mean flow in the valve curtain area and to characterise the interference phenomena between the two intake valves. The investigation has shown the significant influence of the valve lift on the volumetric efficiency of the intake apparatus. Moreover, the experimental analysis has highlighted that the valve-valve interference phenomena have a relevant impact on the head breathability, on the flow development within the combustion chamber and on the velocity standard deviations.

  14. Analysis of construction dynamic plan using fuzzy critical path method

    Directory of Open Access Journals (Sweden)

    Kurij Kazimir V.

    2014-01-01

    Full Text Available Critical Path Method (CPM technique has become widely recognized as valuable tool for the planning and scheduling large construction projects. The aim of this paper is to present an analytical method for finding the Critical Path in the precedence network diagram where the duration of each activity is represented by a trapezoidal fuzzy number. This Fuzzy Critical Path Method (FCPM uses a defuzzification formula for trapezoidal fuzzy number and applies it on the total float (slack time for each activity in the fuzzy precedence network to find the critical path. The method presented in this paper is very effective in determining the critical activities and finding the critical paths.

  15. Analysis of flashing and swelling phenomena in tanks of nuclear power plants; the importance of bubble growth dynamics and bubble transport models with size tracking

    Energy Technology Data Exchange (ETDEWEB)

    Cerezo A, E. [University of Caribe, Department of Basics Sciences and Engineering, Lote 1, Manzana 1, Region 78, esq. Fracc. Tabachines, 77500 Cancun, Quintana Roo (Mexico)]. E-mail: ecerezo@unicaribe.edu.mx; Munoz C, J.L. [Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia, Camino de Vera 14, 46022 Valencia (Spain)

    2004-07-01

    This paper presents a non-equilibrium model to describe flashing phenomena in tanks and cooling pools. The present model is based on Watanabe's work that we have extended by developing a realistic model for the growth of bubbles. We have made the corresponding venting model, continuity equation, gas and liquid phase energy conservation equations for the model. This model takes into account both drag and virtual mass force. The dynamics of bubble growth plays an important role in two-phase phenomena such as flashing. In our model the growth rate is assumed to be limited by the heat conduction in the liquid. The results of the analytic model were compared with the experimental data of Watanabe [1]. The results have shown that the present model evaluates fairly accurately the pressure evolution, the void fraction and the swelling level of a tank.

  16. Multi-Dimensional Analysis of the Forced Bubble Dynamics Associated with Bubble Fusion Phenomena. Final Topical Report

    Energy Technology Data Exchange (ETDEWEB)

    Lahey, Jr., Richard T. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Multiphase Research and Dept. of Mechanical, Aeronautical and Nuclear Engineering; Jansen, Kenneth E. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Multiphase Research and Dept. of Mechanical, Aeronautical and Nuclear Engineering; Nagrath, Sunitha [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Multiphase Research and Dept. of Mechanical, Aeronautical and Nuclear Engineering

    2002-12-02

    A new adaptive grid, 3-D FEM hydrodynamic shock (ie, HYDRO )code called PHASTA-2C has been developed and used to investigate bubble implosion phenomena leading to ultra-high temperatures and pressures. In particular, it was shown that nearly spherical bubble compressions occur during bubble implosions and the predicted conditions associated with a recent ORNL Bubble Fusion experiment [Taleyarkhan et al, Science, March, 2002] are consistent with the occurrence of D/D fusion.

  17. Investigating dynamic mechanisms of geological phenomena using methodology of computational geosciences: An example of equal-distant mineralization in a fault

    Institute of Scientific and Technical Information of China (English)

    ZHAO ChongBin; B.E.HOBBS; A.ORD

    2008-01-01

    This paper presents a research methodology associated with approximately a decade old computational geosciences. To demonstrate how it can be used to investigate the dynamic mechanisms of geological phenomenon,we use as an example the equal-distant distribution of gold deposits in a three-dimensional permeable fault within the Yilgarn Craton,Western Australia. The related numerical results demonstrate that: (1) convective pore-fluid flow in fluid-saturated porous media is the controlling dynamic mechanism leading to the equal-distant distribution of gold deposits along the fault; (2)the main characteristic of the new methodology is to change the traditionally used empirical,descriptive and qualitative methodology into the fundamentally scientific principles based predictive and quantitative methodology. Thus,this new methodology provides a modern scientific research tool for investigating the dynamic mechanisms associated with observed geological phenomena in nature.

  18. Investigating dynamic mechanisms of geological phenomena using methodology of computational geosciences:An example of equal-distant mineralization in a fault

    Institute of Scientific and Technical Information of China (English)

    B.E.HOBBS; A.ORD

    2008-01-01

    This paper presents a research methodology associated with approximately a decade old computa- tional geosciences. To demonstrate how it can be used to investigate the dynamic mechanisms of geological phenomenon, we use as an example the equal-distant distribution of gold deposits in a three-dimensional permeable fault within the Yilgarn Craton, Western Australia. The related numerical results demonstrate that: (1) convective pore-fluid flow in fluid-saturated porous media is the control- ling dynamic mechanism leading to the equal-distant distribution of gold deposits along the fault; (2) the main characteristic of the new methodology is to change the traditionally used empirical, descrip- tive and qualitative methodology into the fundamentally scientific principles based predictive and quantitative methodology. Thus, this new methodology provides a modern scientific research tool for investigating the dynamic mechanisms associated with observed geological phenomena in nature.

  19. Transport phenomena II essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena II covers forced convention, temperature distribution, free convection, diffusitivity and the mechanism of mass transfer, convective mass transfer, concentration

  20. Critical Dynamics Behavior of the Wolff Algorithm in the Site-Bond-Correlated Ising Model

    Science.gov (United States)

    Campos, P. R. A.; Onody, R. N.

    Here we apply the Wolff single-cluster algorithm to the site-bond-correlated Ising model and study its critical dynamical behavior. We have verified that the autocorrelation time diminishes in the presence of dilution and correlation, showing that the Wolff algorithm performs even better in such situations. The critical dynamical exponents are also estimated.

  1. Toward Control of Universal Scaling in Critical Dynamics

    Science.gov (United States)

    2016-01-27

    to synergistically combine two powerful and very successful theories for non-linear stochastic dynamics of cooperative multi-component systems , namely...we have now defined various tractable theoretical model systems that will allow the external control of universal dynamical scaling features through...competition models in evolutionary game theory and population dynamics . His calculations specifically address the purported mapping of these systems

  2. Multi-Loop Calculations of Anomalous Exponents in the Models of Critical Dynamics

    Directory of Open Access Journals (Sweden)

    Adzhemyan L. Ts.

    2016-01-01

    Full Text Available The Renormalization group method (RG is applied to the investigation of the E model of critical dynamics, which describes the transition from the normal to the superfluid phase in He4. The technique “Sector decomposition” with R’ operation is used for the calculation of the Feynman diagrams. The RG functions, critical exponents and critical dynamical exponent z, which determines the growth of the relaxation time near the critical point, have been calculated in the two-loop approximation in the framework of ε-expansion. The relevance of a fixed point for helium, where the dynamic scaling is weakly violated, is briefly discussed.

  3. Fundamentals of Fire Phenomena

    DEFF Research Database (Denmark)

    Quintiere, James

    Understanding fire dynamics and combustion is essential in fire safety engineering and in fire science curricula. Engineers and students involved in fire protection, safety and investigation need to know and predict how fire behaves to be able to implement adequate safety measures and hazard...... analyses. Fire phenomena encompass everything about the scientific principles behind fire behaviour. Combining the principles of chemistry, physics, heat and mass transfer, and fluid dynamics necessary to understand the fundamentals of fire phenomena, this book integrates the subject into a clear...... discipline. It covers thermo chemistry including mixtures and chemical reactions; Introduces combustion to the fire protection student; Discusses premixed flames and spontaneous ignition; Presents conservation laws for control volumes, including the effects of fire; Describes the theoretical bases...

  4. Steady water waves with multiple critical layers: interior dynamics

    CERN Document Server

    Ehrnström, Mats; Villari, Gabriele

    2010-01-01

    We study small-amplitude steady water waves with multiple critical layers. Those are rotational two-dimensional gravity-waves propagating over a perfect fluid of finite depth. It is found that arbitrarily many critical layers with cat's-eye vortices are possible, with different structure at different levels within the fluid. The corresponding vorticity depends linearly on the stream function.

  5. Dynamic Diversity: Toward a Contextual Understanding of Critical Mass

    Science.gov (United States)

    Garces, Liliana M.; Jayakumar, Uma M.

    2014-01-01

    Through an analysis of relevant social science evidence, this article provides a deeper understanding of critical mass, a concept that has become central in litigation efforts related to affirmative action admissions policies that seek to further the educational benefits of diversity. We demonstrate that the concept of critical mass requires an…

  6. Universality of quantum critical dynamics in a planar OPO

    CERN Document Server

    Drummond, P D; Drummond, Peter D.; Dechoum, Kaled

    2005-01-01

    We analyze the critical quantum fluctuations in a coherently driven planar optical parametric oscillator. We show that the presence of transverse modes combined with quantum fluctuations changes the behavior of the `quantum image' critical point. This zero-temperature non-equilibrium quantum system has the same universality class as a finite-temperature magnetic Lifshitz transition.

  7. Comparison of the Cahn-Hilliard-Navier-Stokes and Molecular Dynamics Approaches for the Simulation of Droplet Coalescence and Wetting Phenomena

    Science.gov (United States)

    Vaes, Urbain; Aymard, Benjamin; Ravipati, Srikanth; Yatsyshin, Petr; Galindo, Amparo; Kalliadasis, Serafim

    2016-11-01

    Diffuse-interface/Cahn-Hilliard equations, coupled to Navier-Stokes (CHNS), have been used extensively over the last few years in fluid dynamics including interfacial phenomena in multiphase systems. Applications range from turbulent two-phase flows to rheological systems and microfluidic devices. But despite the considerable attention CHNS have received, little work has been undertaken to investigate the extent to which they agree with "first-principles" physical models such as those provided by molecular dynamics (MD). Here we compare MD simulations with solutions of the CHNS system obtained numerically using an efficient and systematic finite-element methodology we have developed recently. For this purpose, we consider two paradigmatic model systems: droplet coalescence and droplet motion on a substrate with varying wettability.

  8. Critical Dynamics : The Expansion of the Master Equation Including a Critical Point

    NARCIS (Netherlands)

    Dekker, H.

    1980-01-01

    In this thesis it is shown how to solve the master equation for a Markov process including a critical point by means of successive approximations in terms of a small parameter. A critical point occurs if, by adjusting an externally controlled quantity, the system shows a transition from normal monos

  9. A mathematical framework for critical transitions: bifurcations, fast-slow systems and stochastic dynamics

    CERN Document Server

    Kuehn, Christian

    2011-01-01

    Bifurcations can cause dynamical systems with slowly varying parameters to transition to far-away attractors. The terms "critical transition" or "tipping point" have been used to describe this situation. Critical transitions have been observed in an astonishingly diverse set of applications from ecosystems and climate change to medicine and finance. The goal of this paper is to bring together a variety of techniques from dynamical systems theory to analyze critical transitions. In particular, we shall focus on identifying indicators for catastrophic shifts in the dynamics. Starting from classical bifurcation theory and incorporating multiple time scale dynamics we are able to give a detailed analysis of local bifurcations that induce critical transitions. We characterize several early warning signs for a transition such as slowing down and bifurcation delay. Then we take into account stochastic effects and proceed to model critical transitions by fast-slow stochastic differential equations. The interplay betw...

  10. A New Global Theory of the Earth's Dynamics a Single Cause Can Explain All the Geophysical and Geological Phenomena

    CERN Document Server

    Rousseau, A

    2005-01-01

    After describing all the contradictions associated with the current Plate Tectonics theory, this paper proposes a model where a single cause can explain all geophysical and geological phenomena. The source of the Earth's activity lies in the difference of the angular velocities of the mantle and of the solid inner core. The friction between both spheres infers heat, which is the cause of the melted iron which constitutes most of the liquid outer core, as well as the source of the global heat flow. The solid inner core angular velocity is supposed to remain steady, while the mantle angular velocity depends on gyroscopic forces (involving acceleration) and slowing down due to external attractions and, principally the motions of mantle plates 2900 km thick. The variations of the geomagnetic field are therefore the direct consequence of the variations of the angular velocity of the mantle relative to that of the inner core. As a result, the biological and tectonic evolutions during geological times are due to tho...

  11. Computational fluid dynamics approaches in quality and hygienic production of semisolid low-moisture foods: a review of critical factors.

    Science.gov (United States)

    Mondal, Arpita; Buchanan, Robert L; Lo, Y Martin

    2014-10-01

    Low-moisture foods have been responsible for a number of salmonellosis outbreaks worldwide over the last few decades, with cross contamination from contaminated equipment being the most predominant source. To date, actions have been focused on stringent hygienic practices prior to production, namely periodical sanitization of the processing equipment and lines. Not only does optimum sanitization require in-depth knowledge on the type and source of contaminants, but also the heat resistance of microorganisms is unique and often dependent on the heat transfer characteristics of the low-moisture foods. Rheological properties, including viscosity, degree of turbulence, and flow characteristics (for example, Newtonian or non-Newtonian) of both liquid and semisolid foods are critical factors impacting the flow behavior that consequently interferes heat transfer and related control elements. The demand for progressively more accurate prediction of complex fluid phenomena has called for the employment of computational fluid dynamics (CFD) to model mass and heat transfer during processing of various food products, ranging from drying to baking. With the aim of improving the quality and safety of low-moisture foods, this article critically reviewed the published literature concerning microbial survival in semisolid low-moisture foods, including chocolate, honey, and peanut butter. Critical rheological properties and state-of-the-art CFD application relevant to quality production of those products were also addressed. It is anticipated that adequate prediction of specific transport properties during optimum sanitization through CFD could be used to solve current and future food safety challenges.

  12. Fundamentals of Fire Phenomena

    DEFF Research Database (Denmark)

    Quintiere, James

    discipline. It covers thermo chemistry including mixtures and chemical reactions; Introduces combustion to the fire protection student; Discusses premixed flames and spontaneous ignition; Presents conservation laws for control volumes, including the effects of fire; Describes the theoretical bases...... analyses. Fire phenomena encompass everything about the scientific principles behind fire behaviour. Combining the principles of chemistry, physics, heat and mass transfer, and fluid dynamics necessary to understand the fundamentals of fire phenomena, this book integrates the subject into a clear...... for empirical aspects of the subject of fire; Analyses ignition of liquids and the importance of evaporation including heat and mass transfer; Features the stages of fire in compartments, and the role of scale modelling in fire. The book is written by Prof. James G. Quintiere from University of Maryland...

  13. Adsorption/desorption phenomena on pure and Teflon AF-coated titania surfaces studied by dynamic contact angle analysis.

    Science.gov (United States)

    Rupp, F; Axmann, D; Ziegler, C; Geis-Gerstorfer, J

    2002-12-15

    As a result of inflammatory processes, plaque formation on dental titanium implants often leads to clinically pathogenic situations. This special biofilm formation on (bio)materials in contact with saliva is initiated by ionic and protein interactions. In this interfacial process, albumin becomes a main constituent of dental pellicle. Interfacial reactions change the surface characteristics. They determine the following steps of macromolecular adsorption and bacterial adhesion. This work focuses on the dynamic contact angle analysis (DCA), which is a tool for online measurements of dynamic changes of wettability without disturbing the interface during detection. Repeatability of the DCA method has been assessed according to the Bland and Altman method. The kinetics and equilibrium data of shifts in the wetting tension hysteresis indicate ionic influences at the titanium/bovine serum albumin (BSA) interface: the Ca-mediated increase of the BSA adsorption on titanium and the adsorption maximum at the isoelectric point (IEP) of BSA. Ti was surface modified by Teflon AF polymeric coatings. The result of the assessment gives reason to consider Teflon AF as a reference material for DCA repeatability studies. This surface modification caused drastic changes in the dynamic interfacial reactions. Shifts in the wetting tensions during DCA adsorption-desorption experiments clearly demonstrated the partially irreversible adsorption of BSA on Teflon AF. In contrast, reversible adsorption behavior was detected on pure Ti surfaces. These findings strengthen the hypothesis that the analysis of dynamic changes in wetting tension and wetting tension hysteresis is a sensitive analytical method for the detection of dynamic interfacial changes at biomaterial/biosystem interfaces during the initial steps of biofilm formation.

  14. Spin dynamics in Tb studied by critical neutron scattering

    DEFF Research Database (Denmark)

    Dietrich, O. W.; Als-Nielsen, Jens Aage

    1971-01-01

    The inelasticity of the critical neutron scattering in Tb was measured at and above the Neel temperature. In the hydrodynamic region the line width Gamma (q=0, kappa 1)=C kappa z1, with z=1.4+or-0.1 and c=4.3+or-0.3 meVAAz. This result deviates from the conventional theory, which predicts...

  15. Critical Dynamics in Quenched 2D Atomic Gases

    Science.gov (United States)

    Larcher, F.; Dalfovo, F.; Proukakis, N. P.

    2016-05-01

    Non-equilibrium dynamics across phase transitions is a subject of intense investigations in diverse physical systems. One of the key issues concerns the validity of the Kibble-Zurek (KZ) scaling law for spontaneous defect creation. The KZ mechanism has been recently studied in cold atoms experiments. Interesting open questions arise in the case of 2D systems, due to the distinct nature of the Berezinskii-Kosterlitz-Thouless (BKT) transition. Our studies rely on the stochastic Gross-Pitaevskii equation. We perform systematic numerical simulations of the spontaneous emergence and subsequent dynamics of vortices in a uniform 2D Bose gas, which is quenched across the BKT phase transition in a controlled manner, focusing on dynamical scaling and KZ-type effects. By varying the transverse confinement, we also look at the extent to which such features can be seen in current experiments. Financial support from EPSRC and Provincia Autonoma di Trento.

  16. Critical scaling in hidden state inference for linear Langevin dynamics

    OpenAIRE

    Bravi, Barbara; Sollich, Peter

    2016-01-01

    We consider the problem of inferring the dynamics of unknown (i.e. hidden) nodes from a set of observed trajectories and we study analytically the average prediction error given by the Extended Plefka Expansion applied to it, as presented in [1]. We focus on a stochastic linear dynamics of continuous degrees of freedom interacting via random Gaussian couplings in the infinite network size limit. The expected error on the hidden time courses can be found as the equal-time hidden-to-hidden cova...

  17. Evidence of dynamic crossover phenomena in water and other glass-forming liquids: experiments, MD simulations and theory

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S H; Zhang, Y; Lagi, M [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Chong, S H [Institute for Molecular Science, Okazaki 444-8585 (Japan); Baglioni, P [Department of Chemistry and CSGI, University of Florence, Sesto Fiorentino, I-50019 Florence (Italy); Mallamace, F, E-mail: sowhsin@mit.ed [Dipartimento di Fisica, Universita di Messina and IRCCS Neurolesi ' Bonino-Pulejo' , I-98166 Messina (Italy)

    2009-12-16

    In a recent quasi-elastic neutron scattering experiment on water confined in a Portland cement paste, we find that this 3D confined water shows a dynamic crossover phenomenon at T{sub L} = 227 +- 5 K. The DSC heat-flow scan upon cooling and an independent measurement of specific heat at constant pressure of confined water in silica gel show a prominent peak at the same temperature. We show in this paper that this type of behavior is common to many other glassy liquids, which also show the crossover temperature in coincidence with the temperature of a small specific heat peak. We also demonstrate with MD simulations that the dynamic crossover phenomenon in confined water is an intrinsic property of bulk water, and is not due to the confinement effect. Recently, an extended version of the mode coupling theory (MCT) including the hopping effect was developed. This theory shows that, instead of a structural arrest transition at T{sub C} predicted by the idealized MCT, a fragile-to-strong dynamic crossover phenomenon takes place instead at T{sub C}, confirming both the experimental and the numerical results. The coherent and incoherent alpha relaxation times can be scaled with the calculated viscosity, showing the same crossover phenomenon. We thus demonstrated with experiments, simulations and theory that a genuine change of dynamical behavior of both water and many glassy liquids happens at the crossover temperature T{sub L}, which is 10-30% higher than the calorimetric glass transition temperature T{sub g}.

  18. Transport phenomena I essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena I includes viscosity, flow of Newtonian fluids, velocity distribution in laminar flow, velocity distributions with more than one independent variable, thermal con

  19. Partial Dynamical Symmetry at Critical-Points of Quantum Phase Transitions

    CERN Document Server

    Leviatan, A

    2007-01-01

    We show that partial dynamical symmetries (PDS) can occur at critical-points of quantum phase transitions, in which case, underlying competing symmetries are conserved exactly by a subset of states, and mix strongly in other states. Several types of PDS are demonstrated with the example of critical-point Hamiltonians for first- and second-order transitions in the framework of the interacting boson model, whose dynamical symmetries correspond to different shape-phases in nuclei.

  20. Classroom Dynamic Assessment: A Critical Examination of Constructs and Practices

    Science.gov (United States)

    Davin, Kristin J.

    2016-01-01

    This article explores the implementation of dynamic assessment (DA) in an elementary school foreign language classroom by considering its theoretical basis and its applicability to second language (L2) teaching, learning, and development. In existing applications of L2 classroom DA, errors serve as a window into learners' instructional needs and…

  1. Local and cluster critical dynamics of the 3d random-site Ising model

    Science.gov (United States)

    Ivaneyko, D.; Ilnytskyi, J.; Berche, B.; Holovatch, Yu.

    2006-10-01

    We present the results of Monte Carlo simulations for the critical dynamics of the three-dimensional site-diluted quenched Ising model. Three different dynamics are considered, these correspond to the local update Metropolis scheme as well as to the Swendsen-Wang and Wolff cluster algorithms. The lattice sizes of L=10-96 are analysed by a finite-size-scaling technique. The site dilution concentration p=0.85 was chosen to minimize the correction-to-scaling effects. We calculate numerical values of the dynamical critical exponents for the integrated and exponential autocorrelation times for energy and magnetization. As expected, cluster algorithms are characterized by lower values of dynamical critical exponent than the local one: also in the case of dilution critical slowing down is more pronounced for the Metropolis algorithm. However, the striking feature of our estimates is that they suggest that dilution leads to decrease of the dynamical critical exponent for the cluster algorithms. This phenomenon is quite opposite to the local dynamics, where dilution enhances critical slowing down.

  2. Mapping between finite temperature classical and zero temperature quantum systems: Quantum critical jamming and quantum dynamical heterogeneities

    Science.gov (United States)

    Nussinov, Zohar; Johnson, Patrick; Graf, Matthias J.; Balatsky, Alexander V.

    2013-05-01

    Many electronic systems (e.g., the cuprate superconductors and heavy fermions) exhibit striking features in their dynamical response over a prominent range of experimental parameters. While there are some empirical suggestions of particular increasing length scales that accompany such transitions in some cases, this identification is not universal and in numerous instances no large correlation length is evident. To better understand, as a matter of principle, such behavior in quantum systems, we extend a known mapping (earlier studied in stochastic or supersymmetric quantum mechanics) between finite temperature classical Fokker-Planck systems and related quantum systems at zero temperature to include general nonequilibrium dynamics. Unlike Feynman mappings or stochastic quantization methods in field theories (as well as more recent holographic type dualities), the classical systems that we consider and their quantum duals reside in the same number of space-time dimensions. The upshot of our very broad and rigorous result is that a Wick rotation exactly relates (i) the dynamics in general finite temperature classical dissipative systems to (ii) zero temperature dynamics in the corresponding dual many-body quantum systems. Using this correspondence, we illustrate that, even in the absence of imposed disorder, many continuum quantum fluid systems (and possible lattice counterparts) may exhibit a zero-point “quantum dynamical heterogeneity” wherein the dynamics, at a given instant, is spatially nonuniform. While the static length scales accompanying this phenomenon do not seem to exhibit a clear divergence in standard correlation functions, the length scale of the dynamical heterogeneities can increase dramatically. We further study “quantum jamming” and illustrate how a hard-core bosonic system can undergo a zero temperature quantum critical metal-to-insulator-type transition with an extremely large effective dynamical exponent z>4 that is consistent with

  3. Mathematical Model for Hit Phenomena

    CERN Document Server

    Ishii, Akira; Hayashi, Takefumi; Matsuda, Naoya; Nakagawa, Takeshi; Arakaki, Hisashi; Yoshida, Narihiko

    2010-01-01

    The mathematical model for hit phenomena in entertainments is presented as a nonlinear, dynamical and non-equilibrium phenomena. The purchase intention for each person is introduced and direct and indirect communications are expressed as two-body and three-body interaction in our model. The mathematical model is expressed as coupled nonlinear differential equations. The important factor in the model is the decay time of rumor for the hit. The calculated results agree very well with revenues of recent 25 movies.

  4. Mathematical modeling of phenomena of dynamic recrystallization during hot plastic deformation in high-carbon bainitic steel

    Directory of Open Access Journals (Sweden)

    T. Dembiczak

    2017-01-01

    Full Text Available Based on the research results, coefficients were determined in constitutive equations, describing the kinetics of dynamic recrystallization in high-carbon bainitic steel during hot deformation. The developed mathematical model takes into account the dependence of changing kinetics in the size evolution of the initial austenite grains, the value of strain, strain rate, temperature and time. Physical simulations were carried out on rectangular specimens measuring 10 × 15 × 20 mm. Compression tests with a plane state of deformation were carried out using a Gleeble 3800.

  5. Neutron scattering studies of dynamic crossover phenomena in a coupled system of biopolymer and its hydration water

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S H; Mallamace, F; Chu, X Q; Kim, C; Lagi, M [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Faraone, A [Dipartmento di Fisica and CNISM, Universita di Messina, Vil. S. Agata CP 55, 98166 Messina (Italy); Fratini, E; Baglioni, P, E-mail: sowhsin@mit.ed [Department of Chemistry and CSGI, University of Florence, 50019 (Italy)

    2009-06-01

    We have observed a Fragile-to-Strong Dynamic Crossover (FSC) phenomenon of the alpha-relaxation time and self-diffusion constant in hydration water of three biopolymers: lysozyme, B-DNA and RNA. The mean squared displacement (MSD) of hydrogen atoms is measured by Elastic Neutron Scattering (ENS) experiments. The alpha-relaxation time is measured by Quasi-Elastic Neutron Scattering (QENS) experiments and the self-diffusion constant by Nuclear Magnetic Resonance (NMR) experiments. We discuss the active role of the FSC of the hydration water in initiating the dynamic crossover phenomenon (so-called glass transition) in the biopolymer. The latter transition controls the flexibility of the biopolymer and sets the low temperature limit of its biofunctionality. Finally, we show an MD simulation of a realistic hydrated powder model of lysozyme and demonstrate the agreement of the MD simulation with the experimental data on the FSC phenomenon in the plot of logarithm of the alpha-relaxation time vs. 1/T.

  6. Transient magneto-peristaltic flow of couple stress biofluids: a magneto-hydro-dynamical study on digestive transport phenomena.

    Science.gov (United States)

    Tripathi, Dharmendra; Anwar Bég, O

    2013-11-01

    Magnetic fields are increasingly being utilized in endoscopy and gastric transport control. In this regard, the present study investigates the influence of a transverse magnetic field in the transient peristaltic rheological transport. An electrically-conducting couple stress non-Newtonian model is employed to accurately simulate physiological fluids in peristaltic flow through a sinusoidally contracting channel of finite length. This model is designed for computing the intra-bolus oesophageal and intestinal pressures during the movement of food bolus in the digestive system under magneto-hydro-dynamic effects. Long wavelength and low Reynolds number approximations have been employed to reduce the governing equations from nonlinear to linear form, this being a valid approach for creeping flows which characterizes physiological dynamics. Analytical approximate solutions for axial velocity, transverse velocity, pressure gradient, local wall shear stress and volumetric flow rate are obtained for the non-dimensional conservation equations subject to appropriate boundary conditions. The effects of couple stress parameter and transverse magnetic field on the velocity profile, pressure distribution, local wall shear stress and the averaged flow rate are discussed with the aid of computational results. The comparative study of non-integral and integral number of waves propagating along the finite length channel is also presented. Magnetic field and non-Newtonian properties are found to strongly influence peristaltic transport.

  7. Dynamics of parabolic problems with memory. Subcritical and critical nonlinearities

    Science.gov (United States)

    Li, Xiaojun

    2016-08-01

    In this paper, we study the long-time behavior of the solutions of non-autonomous parabolic equations with memory in cases when the nonlinear term satisfies subcritical and critical growth conditions. In order to do this, we show that the family of processes associated to original systems with heat source f(x, t) being translation bounded in Lloc 2 ( R ; L 2 ( Ω ) ) is dissipative in higher energy space M α , 0 < α ≤ 1, and possesses a compact uniform attractor in M 0 .

  8. Dynamical and statistical phenomena of circulation and heat transfer in periodically forced rotating turbulent Rayleigh-Benard convection

    CERN Document Server

    Sterl, Sebastian; Zhong, Jin-Qiang

    2016-01-01

    In this paper, we present results from an experimental study into turbulent Rayleigh-Benard convection forced externally by periodically modulated unidirectional rotation rates. We find that the azimuthal rotation velocity $\\dot{\\theta}$(t) and thermal amplitude $\\delta$(t) of the large-scale circulation (LSC) are modulated by the forcing, exhibiting a variety of dynamics including increasing phase delays and a resonant peak in the amplitude of $\\dot{\\theta}$(t). We also focus on the influence of modulated rotation rates on the frequency of occurrence $\\eta$ of stochastic cessation/reorientation events, and on the interplay between such events and the periodically modulated response of $\\dot{\\theta}$(t). Here we identify a mechanism by which $\\eta$ can be amplfied by the modulated response and these normally stochastic events can occur with high regularity. We provide a modeling framework that explains the observed amplitude and phase responses, and extend this approach to make predictions for the occurrence ...

  9. Quantifying transient 3D dynamical phenomena of single mRNA particles in live yeast cell measurements.

    Science.gov (United States)

    Calderon, Christopher P; Thompson, Michael A; Casolari, Jason M; Paffenroth, Randy C; Moerner, W E

    2013-12-12

    Single-particle tracking (SPT) has been extensively used to obtain information about diffusion and directed motion in a wide range of biological applications. Recently, new methods have appeared for obtaining precise (10s of nm) spatial information in three dimensions (3D) with high temporal resolution (measurements obtained every 4 ms), which promise to more accurately sense the true dynamical behavior in the natural 3D cellular environment. Despite the quantitative 3D tracking information, the range of mathematical methods for extracting information about the underlying system has been limited mostly to mean-squared displacement analysis and other techniques not accounting for complex 3D kinetic interactions. There is a great need for new analysis tools aiming to more fully extract the biological information content from in vivo SPT measurements. High-resolution SPT experimental data has enormous potential to objectively scrutinize various proposed mechanistic schemes arising from theoretical biophysics and cell biology. At the same time, methods for rigorously checking the statistical consistency of both model assumptions and estimated parameters against observed experimental data (i.e., goodness-of-fit tests) have not received great attention. We demonstrate methods enabling (1) estimation of the parameters of 3D stochastic differential equation (SDE) models of the underlying dynamics given only one trajectory; and (2) construction of hypothesis tests checking the consistency of the fitted model with the observed trajectory so that extracted parameters are not overinterpreted (the tools are applicable to linear or nonlinear SDEs calibrated from nonstationary time series data). The approach is demonstrated on high-resolution 3D trajectories of single ARG3 mRNA particles in yeast cells in order to show the power of the methods in detecting signatures of transient directed transport. The methods presented are generally relevant to a wide variety of 2D and 3D SPT

  10. Dynamical density fluctuations of superfluids near the critical velocity.

    Science.gov (United States)

    Kato, Yusuke; Watabe, Shohei

    2010-07-16

    We propose a stability criterion of superfluids in condensed Bose-Einstein systems, which incorporates the spectral function or the autocorrelation function of the local density. Within the Gross-Pitaevskii-Bogoliubov theory, we demonstrate the validity of our criterion for the soliton-emission instability, with use of explicit forms of zero modes of the Bogoliubov equation and a dynamical scaling near the saddle-node bifurcation. We also show that the criterion is applicable to the Landau phonon instability and the Landau roton instability within the single-mode approximation.

  11. CriPS: Critical Dynamics in Particle Swarm Optimization

    OpenAIRE

    Erskine, Adam; Herrmann, J Michael

    2014-01-01

    Particle Swarm Optimisation (PSO) makes use of a dynamical system for solving a search task. Instead of adding search biases in order to improve performance in certain problems, we aim to remove algorithm-induced scales by controlling the swarm with a mechanism that is scale-free except possibly for a suppression of scales beyond the system size. In this way a very promising performance is achieved due to the balance of large-scale exploration and local search. The resulting algorithm shows e...

  12. A mathematical framework for critical transitions: Bifurcations, fast-slow systems and stochastic dynamics

    Science.gov (United States)

    Kuehn, Christian

    2011-06-01

    Bifurcations can cause dynamical systems with slowly varying parameters to transition to far-away attractors. The terms “critical transition” or “tipping point” have been used to describe this situation. Critical transitions have been observed in an astonishingly diverse set of applications from ecosystems and climate change to medicine and finance. The main goal of this paper is to give an overview which standard mathematical theories can be applied to critical transitions. We shall focus on early-warning signs that have been suggested to predict critical transitions and point out what mathematical theory can provide in this context. Starting from classical bifurcation theory and incorporating multiple time scale dynamics one can give a detailed analysis of local bifurcations that induce critical transitions. We suggest that the mathematical theory of fast-slow systems provides a natural definition of critical transitions. Since noise often plays a crucial role near critical transitions the next step is to consider stochastic fast-slow systems. The interplay between sample path techniques, partial differential equations and random dynamical systems is highlighted. Each viewpoint provides potential early-warning signs for critical transitions. Since increasing variance has been suggested as an early-warning sign we examine it in the context of normal forms analytically, numerically and geometrically; we also consider autocorrelation numerically. Hence we demonstrate the applicability of early-warning signs for generic models. We end with suggestions for future directions of the theory.

  13. Dynamical Phenomena in an Optical-Wavelength Phonon Laser (Phaser): Nonlinear Resonances and Self-Organized Mode Alternation

    CERN Document Server

    Makovetskii, D N

    2011-01-01

    This is a part of an overview of my early studies on nonlinear spin-phonon dynamics in solid state optical-wavelength phonon lasers (phasers) started in 1984. The main goal of this work is a short description and a qualitative analysis of experimental data on low-frequency nonlinear resonances revealed in a nonautonomous ruby phaser. Under phaser pumping modulation near these resonances, an unusual kind of self-organized motions in the ruby spin-phonon system was observed by me in 1984 for the first time. The original technique of optical-wavelength microwave-frequency acoustic stimulated emission (SE) detection and microwave-frequency power spectra (MFPS) analysis was used in these experiments (description of the technique see: D.N.Makovetskii, Cand. Sci. Diss., Kharkov, 1983). The real time evolution of MFPS was studied using this technique at scales up to several hours. The phenomenon of the self-organized periodic alternation of SE phonon modes was experimentally revealed at hyperlow frequencies from abou...

  14. Quantum wavepacket ab initio molecular dynamics: an approach for computing dynamically averaged vibrational spectra including critical nuclear quantum effects.

    Science.gov (United States)

    Sumner, Isaiah; Iyengar, Srinivasan S

    2007-10-18

    We have introduced a computational methodology to study vibrational spectroscopy in clusters inclusive of critical nuclear quantum effects. This approach is based on the recently developed quantum wavepacket ab initio molecular dynamics method that combines quantum wavepacket dynamics with ab initio molecular dynamics. The computational efficiency of the dynamical procedure is drastically improved (by several orders of magnitude) through the utilization of wavelet-based techniques combined with the previously introduced time-dependent deterministic sampling procedure measure to achieve stable, picosecond length, quantum-classical dynamics of electrons and nuclei in clusters. The dynamical information is employed to construct a novel cumulative flux/velocity correlation function, where the wavepacket flux from the quantized particle is combined with classical nuclear velocities to obtain the vibrational density of states. The approach is demonstrated by computing the vibrational density of states of [Cl-H-Cl]-, inclusive of critical quantum nuclear effects, and our results are in good agreement with experiment. A general hierarchical procedure is also provided, based on electronic structure harmonic frequencies, classical ab initio molecular dynamics, computation of nuclear quantum-mechanical eigenstates, and employing quantum wavepacket ab initio dynamics to understand vibrational spectroscopy in hydrogen-bonded clusters that display large degrees of anharmonicities.

  15. MULTISCALE PHENOMENA IN MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    A. BISHOP

    2000-09-01

    This project developed and supported a technology base in nonequilibrium phenomena underpinning fundamental issues in condensed matter and materials science, and applied this technology to selected problems. In this way the increasingly sophisticated synthesis and characterization available for classes of complex electronic and structural materials provided a testbed for nonlinear science, while nonlinear and nonequilibrium techniques helped advance our understanding of the scientific principles underlying the control of material microstructure, their evolution, fundamental to macroscopic functionalities. The project focused on overlapping areas of emerging thrusts and programs in the Los Alamos materials community for which nonlinear and nonequilibrium approaches will have decisive roles and where productive teamwork among elements of modeling, simulations, synthesis, characterization and applications could be anticipated--particularly multiscale and nonequilibrium phenomena, and complex matter in and between fields of soft, hard and biomimetic materials. Principal topics were: (i) Complex organic and inorganic electronic materials, including hard, soft and biomimetic materials, self-assembly processes and photophysics; (ii) Microstructure and evolution in multiscale and hierarchical materials, including dynamic fracture and friction, dislocation and large-scale deformation, metastability, and inhomogeneity; and (iii) Equilibrium and nonequilibrium phases and phase transformations, emphasizing competing interactions, frustration, landscapes, glassy and stochastic dynamics, and energy focusing.

  16. Dynamic critical exponents for Swendsen Wang and Wolff algorithms obtained by a nonequilibrium relaxation method

    Science.gov (United States)

    Du, Jianqing; Zheng, Bo; Wang, Jian-Sheng

    2006-05-01

    Using a nonequilibrium relaxation method, we calculate the dynamic critical exponent z of the two-dimensional Ising model for the Swendsen-Wang and Wolff algorithms. We examine dynamic relaxation processes following a quench from a disordered or an ordered initial state to the critical temperature Tc, and measure the exponential relaxation time of the system energy. For the Swendsen-Wang algorithm with an ordered or a disordered initial state, and for the Wolff algorithm with an ordered initial state, the exponential relaxation time fits well to a logarithmic size dependence up to a lattice size L = 8192. For the Wolff algorithm with a disordered initial state, we obtain an effective dynamic exponent zexp = 1.19(2) up to L = 2048. For comparison, we also compute the effective dynamic exponents through the integrated correlation times. In addition, an exact result of the Swendsen-Wang dynamic spectrum of a one-dimensional Ising chain is derived.

  17. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (%3C50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the "glue" that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  18. Dynamical critical behavior in a cellular model of superconducting vortex avalanches

    Science.gov (United States)

    Vadakkan, Tegy John

    Bak, Tang, and Wiesenfeld showed that certain driven dissipative systems with many degrees of freedom organize into a critical state characterized by avalanche dynamics and power law distribution of avalanche sizes and durations. They called this phenomenon self-organized criticality and sandpile became the prototype of such dynamical systems. Universality in these systems is not yet well established. Forty years ago, de Gennes noted that the Bean state in a type-II superconductor is similar to a sandpile. Motivated by strong experimental evidences, Bassler and Paczuski (BP) proposed a 2D sandpile model to study self-organization in the dynamics of vortices in superconductors. In this dissertation, the effect of anisotropy in the vortex-vortex interaction, stochasticity in the vortex toppling rule, and the configuration of the pinning centers on the scaling properties of the avalanches in the BP model is studied. Also, universality in the cellular model of vortex dynamics is investigated.

  19. Mean-field dynamic criticality and geometric transition in the Gaussian core model

    Science.gov (United States)

    Coslovich, Daniele; Ikeda, Atsushi; Miyazaki, Kunimasa

    2016-04-01

    We use molecular dynamics simulations to investigate dynamic heterogeneities and the potential energy landscape of the Gaussian core model (GCM). Despite the nearly Gaussian statistics of particles' displacements, the GCM exhibits giant dynamic heterogeneities close to the dynamic transition temperature. The divergence of the four-point susceptibility is quantitatively well described by the inhomogeneous version of the mode-coupling theory. Furthermore, the potential energy landscape of the GCM is characterized by large energy barriers, as expected from the lack of activated, hopping dynamics, and display features compatible with a geometric transition. These observations demonstrate that all major features of mean-field dynamic criticality can be observed in a physically sound, three-dimensional model.

  20. Molecular dynamics simulation of a binary mixture near the lower critical point.

    Science.gov (United States)

    Pousaneh, Faezeh; Edholm, Olle; Maciołek, Anna

    2016-07-07

    2,6-lutidine molecules mix with water at high and low temperatures but in a wide intermediate temperature range a 2,6-lutidine/water mixture exhibits a miscibility gap. We constructed and validated an atomistic model for 2,6-lutidine and performed molecular dynamics simulations of 2,6-lutidine/water mixture at different temperatures. We determined the part of demixing curve with the lower critical point. The lower critical point extracted from our data is located close to the experimental one. The estimates for critical exponents obtained from our simulations are in a good agreement with the values corresponding to the 3D Ising universality class.

  1. Many-body localization and new critical phenomena in regular random graphs and constrained Erd\\H{o}s-Renyi networks

    CERN Document Server

    Avetisov, V; Nechaev, S; Valba, O

    2016-01-01

    We consider from the localization perspective the new critical behavior discovered recently for the regular random graphs (RRG) and constrained Erd\\H{o}s-Renyi networks (CERN). The diagonal disorder for standard models, we replace by the fugacity $\\mu$ of triads in the RRG and CERN. At some critical value of $\\mu$ the network decays into the maximally possible number of almost full graphs, and the adjacency matrix acquires the two-gapped structure. We find that the eigenvalue statistics corresponds to delocalized states in the central zone, and to the localized states in the side one. The mobility edge lies between zones. We apply these findings to the many-body localization assuming the approximation of the hierarchical structure of the Fock space (for some interacting many-body system) by the RGG and by CERN with some vertex degree. We allow the 3-cycles in the Fock space and identify particles in the many-body system above the phase transition with clusters in the RRG. We discuss the controversial issue of...

  2. Fermi-surface collapse and dynamical scaling near a quantum-critical point.

    Science.gov (United States)

    Friedemann, Sven; Oeschler, Niels; Wirth, Steffen; Krellner, Cornelius; Geibel, Christoph; Steglich, Frank; Paschen, Silke; Kirchner, Stefan; Si, Qimiao

    2010-08-17

    Quantum criticality arises when a macroscopic phase of matter undergoes a continuous transformation at zero temperature. While the collective fluctuations at quantum-critical points are being increasingly recognized as playing an important role in a wide range of quantum materials, the nature of the underlying quantum-critical excitations remains poorly understood. Here we report in-depth measurements of the Hall effect in the heavy-fermion metal YbRh(2)Si(2), a prototypical system for quantum criticality. We isolate a rapid crossover of the isothermal Hall coefficient clearly connected to the quantum-critical point from a smooth background contribution; the latter exists away from the quantum-critical point and is detectable through our studies only over a wide range of magnetic field. Importantly, the width of the critical crossover is proportional to temperature, which violates the predictions of conventional theory and is instead consistent with an energy over temperature, E/T, scaling of the quantum-critical single-electron fluctuation spectrum. Our results provide evidence that the quantum-dynamical scaling and a critical Kondo breakdown simultaneously operate in the same material. Correspondingly, we infer that macroscopic scale-invariant fluctuations emerge from the microscopic many-body excitations associated with a collapsing Fermi-surface. This insight is expected to be relevant to the unconventional finite-temperature behavior in a broad range of strongly correlated quantum systems.

  3. Gauge dependence of the critical dynamics at the superconducting phase transition

    Directory of Open Access Journals (Sweden)

    M.Dudka

    2007-01-01

    Full Text Available The critical dynamics of superconductors in the charged regime is reconsidered within field-theory. For the dynamics, the Ginzburg-Landau model with complex order parameter coupled to the gauge field suggested earlier [Lannert et al. Phys. Rev. Lett. 92, 097004 (2004] is used. Assuming relaxational dynamics for both quantities, the renormalization group functions within one loop approximation are recalculated for different choices of the gauge. A gauge independent result for the divergence of the melectric conductivity is obtained only at the weak scaling fixed point unstable in one loop order where the timescales of the order parameter and the gauge field are different.

  4. Sustainability from the Occurrence of Critical Dynamic Power System Blackout Determined by Using the Stochastic Event Tree Technique

    National Research Council Canada - National Science Library

    Muhammad Murtadha Othman; Nur Ashida Salim; Ismail Musirin

    2017-01-01

    .... This paper presents the proposed stochastic event tree technique used to assess the sustainability against the occurrence of dynamic power system blackout emanating from implication of critical...

  5. Euler Strut: A Mechanical Analogy for Dynamics in the Vicinity of a Critical Point

    Science.gov (United States)

    Bobnar, Jaka; Susman, Katarina; Parsegian, V. Adrian; Rand, Peter R.; Cepic, Mojca; Podgornik, Rudolf

    2011-01-01

    An anchored elastic filament (Euler strut) under an external point load applied to its free end is a simple model for a second-order phase transition. In the static case, a load greater than the critical load causes a Euler buckling instability, leading to a change in the filament's shape. The analysis of filament dynamics with an external point…

  6. Analysis of critical neutron- scattering data from iron and dynamical scaling theory

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1970-01-01

    Experimental three- axis spectrometer data of critical neutron- scattering data from Fe are reanalyzed and compared with the recent theoretical prediction by P. Resibois and C. Piette. The reason why the spin- diffusion parameter did not obey the prediction of dynamical scaling theory is indicated...

  7. Euler Strut: A Mechanical Analogy for Dynamics in the Vicinity of a Critical Point

    Science.gov (United States)

    Bobnar, Jaka; Susman, Katarina; Parsegian, V. Adrian; Rand, Peter R.; Cepic, Mojca; Podgornik, Rudolf

    2011-01-01

    An anchored elastic filament (Euler strut) under an external point load applied to its free end is a simple model for a second-order phase transition. In the static case, a load greater than the critical load causes a Euler buckling instability, leading to a change in the filament's shape. The analysis of filament dynamics with an external point…

  8. Complex Phenomena in Nanoscale Systems

    CERN Document Server

    Casati, Giulio

    2009-01-01

    Nanoscale physics has become one of the rapidly developing areas of contemporary physics because of its direct relevance to newly emerging area, nanotechnologies. Nanoscale devices and quantum functional materials are usually constructed based on the results of fundamental studies on nanoscale physics. Therefore studying physical phenomena in nanosized systems is of importance for progressive development of nanotechnologies. In this context study of complex phenomena in such systems and using them for controlling purposes is of great practical importance. Namely, such studies are brought together in this book, which contains 27 papers on various aspects of nanoscale physics and nonlinear dynamics.

  9. Spinodals and critical point using short-time dynamics for a simple model of liquid.

    Science.gov (United States)

    Loscar, Ernesto S; Ferrara, C Gastón; Grigera, Tomás S

    2016-04-07

    We have applied the short-time dynamics method to the gas-liquid transition to detect the supercooled gas instability (gas spinodal) and the superheated liquid instability (liquid spinodal). Using Monte Carlo simulation, we have obtained the two spinodals for a wide range of pressure in sub-critical and critical conditions and estimated the critical temperature and pressure. Our method is faster than previous approaches and allows studying spinodals without needing equilibration of the system in the metastable region. It is thus free of the extrapolation problems present in other methods, and in principle could be applied to systems such as glass-forming liquids, where equilibration is very difficult even far from the spinodal. We have also done molecular dynamics simulations, where we find the method again able to detect the both spinodals. Our results are compared with different previous results in the literature and show a good agreement.

  10. Fractal and Small-World Networks Formed by Self-Organized Critical Dynamics

    Science.gov (United States)

    Watanabe, Akitomo; Mizutaka, Shogo; Yakubo, Kousuke

    2015-11-01

    We propose a dynamical model in which a network structure evolves in a self-organized critical (SOC) manner and explain a possible origin of the emergence of fractal and small-world networks. Our model combines a network growth and its decay by failures of nodes. The decay mechanism reflects the instability of large functional networks against cascading overload failures. It is demonstrated that the dynamical system surely exhibits SOC characteristics, such as power-law forms of the avalanche size distribution, the cluster size distribution, and the distribution of the time interval between intermittent avalanches. During the network evolution, fractal networks are spontaneously generated when networks experience critical cascades of failures that lead to a percolation transition. In contrast, networks far from criticality have small-world structures. We also observe the crossover behavior from fractal to small-world structure in the network evolution.

  11. Fractal and Small-World Networks Formed by Self-Organized Critical Dynamics

    CERN Document Server

    Watanabe, Akitomo; Yakubo, Kousuke

    2015-01-01

    We propose a dynamical model in which a network structure evolves in a self-organized critical (SOC) manner and explain a possible origin of the emergence of fractal and small-world networks. Our model combines a network growth and its decay by failures of nodes. The decay mechanism reflects the instability of large functional networks against cascading overload failures. It is demonstrated that the dynamical system surely exhibits SOC characteristics, such as power-law forms of the avalanche size distribution, the cluster size distribution, and the distribution of the time interval between intermittent avalanches. During the network evolution, fractal networks are spontaneously generated when networks experience critical cascades of failures that lead to a percolation transition. In contrast, networks far from criticality have small-world structures. We also observe the crossover behavior from fractal to small-world structure in the network evolution.

  12. Maximizing Sensory Dynamic Range by Tuning the Cortical State to Criticality.

    Directory of Open Access Journals (Sweden)

    Shree Hari Gautam

    2015-12-01

    Full Text Available Modulation of interactions among neurons can manifest as dramatic changes in the state of population dynamics in cerebral cortex. How such transitions in cortical state impact the information processing performed by cortical circuits is not clear. Here we performed experiments and computational modeling to determine how somatosensory dynamic range depends on cortical state. We used microelectrode arrays to record ongoing and whisker stimulus-evoked population spiking activity in somatosensory cortex of urethane anesthetized rats. We observed a continuum of different cortical states; at one extreme population activity exhibited small scale variability and was weakly correlated, the other extreme had large scale fluctuations and strong correlations. In experiments, shifts along the continuum often occurred naturally, without direct manipulation. In addition, in both the experiment and the model we directly tuned the cortical state by manipulating inhibitory synaptic interactions. Our principal finding was that somatosensory dynamic range was maximized in a specific cortical state, called criticality, near the tipping point midway between the ends of the continuum. The optimal cortical state was uniquely characterized by scale-free ongoing population dynamics and moderate correlations, in line with theoretical predictions about criticality. However, to reproduce our experimental findings, we found that existing theory required modifications which account for activity-dependent depression. In conclusion, our experiments indicate that in vivo sensory dynamic range is maximized near criticality and our model revealed an unanticipated role for activity-dependent depression in this basic principle of cortical function.

  13. Maximizing Sensory Dynamic Range by Tuning the Cortical State to Criticality

    Science.gov (United States)

    Gautam, Shree Hari; Hoang, Thanh T.; McClanahan, Kylie; Grady, Stephen K.; Shew, Woodrow L.

    2015-01-01

    Modulation of interactions among neurons can manifest as dramatic changes in the state of population dynamics in cerebral cortex. How such transitions in cortical state impact the information processing performed by cortical circuits is not clear. Here we performed experiments and computational modeling to determine how somatosensory dynamic range depends on cortical state. We used microelectrode arrays to record ongoing and whisker stimulus-evoked population spiking activity in somatosensory cortex of urethane anesthetized rats. We observed a continuum of different cortical states; at one extreme population activity exhibited small scale variability and was weakly correlated, the other extreme had large scale fluctuations and strong correlations. In experiments, shifts along the continuum often occurred naturally, without direct manipulation. In addition, in both the experiment and the model we directly tuned the cortical state by manipulating inhibitory synaptic interactions. Our principal finding was that somatosensory dynamic range was maximized in a specific cortical state, called criticality, near the tipping point midway between the ends of the continuum. The optimal cortical state was uniquely characterized by scale-free ongoing population dynamics and moderate correlations, in line with theoretical predictions about criticality. However, to reproduce our experimental findings, we found that existing theory required modifications which account for activity-dependent depression. In conclusion, our experiments indicate that in vivo sensory dynamic range is maximized near criticality and our model revealed an unanticipated role for activity-dependent depression in this basic principle of cortical function. PMID:26623645

  14. Phase transitions, nonequilibrium dynamics, and critical behavior of strongly interacting systems

    Energy Technology Data Exchange (ETDEWEB)

    Mottola, E.; Bhattacharya, T.; Cooper, F. [and others

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. In this effort, large-scale simulations of strongly interacting systems were performed and a variety of approaches to the nonequilibrium dynamics of phase transitions and critical behavior were investigated. Focus areas included (1) the finite-temperature quantum chromodynamics phase transition and nonequilibrium dynamics of a new phase of matter (the quark-gluon plasma) above the critical temperature, (2) nonequilibrium dynamics of a quantum fields using mean field theory, and (3) stochastic classical field theoretic models with applications to spinodal decomposition and structural phase transitions in a variety of systems, such as spin chains and shape memory alloys.

  15. Selective Maturation of Temporal Dynamics of Intracortical Excitatory Transmission at the Critical Period Onset.

    Science.gov (United States)

    Miao, Qinglong; Yao, Li; Rasch, Malte J; Ye, Qian; Li, Xiang; Zhang, Xiaohui

    2016-08-01

    Although the developmental maturation of cortical inhibitory synapses is known to be a critical factor in gating the onset of critical period (CP) for experience-dependent cortical plasticity, how synaptic transmission dynamics of other cortical synapses are regulated during the transition to CP remains unknown. Here, by systematically examining various intracortical synapses within layer 4 of the mouse visual cortex, we demonstrate that synaptic temporal dynamics of intracortical excitatory synapses on principal cells (PCs) and inhibitory parvalbumin- or somatostatin-expressing cells are selectively regulated before the CP onset, whereas those of intracortical inhibitory synapses and long-range thalamocortical excitatory synapses remain unchanged. This selective maturation of synaptic dynamics results from a ubiquitous reduction of presynaptic release and is dependent on visual experience. These findings provide an additional essential circuit mechanism for regulating CP timing in the developing visual cortex.

  16. Selective Maturation of Temporal Dynamics of Intracortical Excitatory Transmission at the Critical Period Onset

    Directory of Open Access Journals (Sweden)

    Qinglong Miao

    2016-08-01

    Full Text Available Although the developmental maturation of cortical inhibitory synapses is known to be a critical factor in gating the onset of critical period (CP for experience-dependent cortical plasticity, how synaptic transmission dynamics of other cortical synapses are regulated during the transition to CP remains unknown. Here, by systematically examining various intracortical synapses within layer 4 of the mouse visual cortex, we demonstrate that synaptic temporal dynamics of intracortical excitatory synapses on principal cells (PCs and inhibitory parvalbumin- or somatostatin-expressing cells are selectively regulated before the CP onset, whereas those of intracortical inhibitory synapses and long-range thalamocortical excitatory synapses remain unchanged. This selective maturation of synaptic dynamics results from a ubiquitous reduction of presynaptic release and is dependent on visual experience. These findings provide an additional essential circuit mechanism for regulating CP timing in the developing visual cortex.

  17. Magnetic phenomena in holographic superconductivity with Lifshitz scaling

    Directory of Open Access Journals (Sweden)

    Aldo Dector

    2015-09-01

    Full Text Available We investigate the effects of Lifshitz dynamical critical exponent z on a family of minimal D=4+1 holographic superconducting models, with a particular focus on magnetic phenomena. We see that it is possible to have a consistent Ginzburg–Landau approach to holographic superconductivity in a Lifshitz background. By following this phenomenological approach we are able to compute a wide array of physical quantities. We also calculate the Ginzburg–Landau parameter for different condensates, and conclude that in systems with higher dynamical critical exponent, vortex formation is more strongly unfavored energetically and exhibits a stronger Type I behavior. Finally, following the perturbative approach proposed by Maeda, Natsuume and Okamura, we calculate the critical magnetic field of our models for different values of z.

  18. Unified Treatise of Phenomena of Seismic Fusion-Fission Under Seismonomy in the Light of Monistic Weltanschauung: the Doctrine of Dynamics Monism With Implication to the Earthquake Source Physics}

    Science.gov (United States)

    Zaurov, D.

    2006-12-01

    Established profoundly new conceptual framework by the five postulates of seismonomy, enables unified treatise of processes such as dynamic structural devastation, seismic blowing up of mount ridges, collision physics, meteorite impact cratering, and seismic global faulting with insight into the earthquake source physics. Hence, by establishing the parametric method of identification of natural modes and then Parametric Scan- Window Observation of Dynamic Responses (PSW-method), it becomes possible to obtain crucial field data. Thus, earth-dam dynamics data revealed an essential non-stationarity of dam's dynamic characteristics throughout earthquakes, the effect of stochastic alternation of the locally-stationary modal states with the discrete characteristics of their spectral distribution. At this point, in the course of other, separate line of far beyond lasting quest concerning metaphysical constituents of matter, and then constitutive relation between excited modal oscillation of structures and causal pattern of their fracture, the results of such analysis, resuming obscurity of the well known jaggedness of observing earthquake spectra, were illuminated and perceived. It was succeeded, on the one hand, to establish unitary conceptualized framework of seismic records analysis consisting both the PSW- and spectral- analysis, which reformulated to be a statistical representation complementary to PSW-method, and, on the other hand, to realize genesis of the doctrine of dynamics monism consisting concepts of both: fission-fusion dynamics and dynamics coherentism as an inspiration of the paradigm of seismic fusion-fission phenomena. Global faulting originating straight plane faults, which often stretch through large scale substantially inhomogeneous volumes, are, uncontestably, the result of dynamics fission, the first step of dynamics binary division of an emerged geoseismoid onto two secondary seismoids with a potential, occasionally stretched rupture plane. That

  19. Qualitative Analysis of Critical Transitions in Complex Disease Propagation from a Dynamical Systems Perspective

    Science.gov (United States)

    Wang, Gang; Zou, Xiufen

    2016-12-01

    Considerable evidence suggests that in complex diseases the deteriorations are often abrupt, and can be viewed as a bifurcation or a critical transition from one asymptotically stable equilibrium to another one at a tipping point. Here, we propose some new ideas to detect early-warning signals of such critical transitions from the perspective of qualitative theory of ordinary differential equations. Specifically, we theoretically derive three indicators that serve as a general early-warning signal indicating an imminent bifurcation or sudden deterioration before the critical transition occurs. Then, we verify our theoretical results by numerical simulations for three examples. Our work forms a starting point to motivate new mathematical insights into predictability for critical transitions of dynamical systems from a new perspective.

  20. Dynamics and controls of urban heat sink and island phenomena in a desert city: Development of a local climate zone scheme using remotely-sensed inputs

    Science.gov (United States)

    Nassar, Ahmed K.; Blackburn, G. Alan; Whyatt, J. Duncan

    2016-09-01

    This study aims to determine the dynamics and controls of Surface Urban Heat Sinks (SUHS) and Surface Urban Heat Islands (SUHI) in desert cities, using Dubai as a case study. A Local Climate Zone (LCZ) schema was developed to subdivide the city into different zones based on similarities in land cover and urban geometry. Proximity to the Gulf Coast was also determined for each LCZ. The LCZs were then used to sample seasonal and daily imagery from the MODIS thermal sensor to determine Land Surface Temperature (LST) variations relative to desert sand. Canonical correlation techniques were then applied to determine which factors explained the variability between urban and desert LST. Our results indicate that the daytime SUHS effect is greatest during the summer months (typically ∼3.0 °C) with the strongest cooling effects in open high-rise zones of the city. In contrast, the night-time SUHI effect is greatest during the winter months (typically ∼3.5 °C) with the strongest warming effects in compact mid-rise zones of the city. Proximity to the Arabian Gulf had the largest influence on both SUHS and SUHI phenomena, promoting daytime cooling in the summer months and night-time warming in the winter months. However, other parameters associated with the urban environment such as building height had an influence on daytime cooling, with larger buildings promoting shade and variations in airflow. Likewise, other parameters such as sky view factor contributed to night-time warming, with higher temperatures associated with limited views of the sky.

  1. Correlations induced by depressing synapses in critically self-organized networks with quenched dynamics

    Science.gov (United States)

    Campos, João Guilherme Ferreira; Costa, Ariadne de Andrade; Copelli, Mauro; Kinouchi, Osame

    2017-04-01

    In a recent work, mean-field analysis and computer simulations were employed to analyze critical self-organization in networks of excitable cellular automata where randomly chosen synapses in the network were depressed after each spike (the so-called annealed dynamics). Calculations agree with simulations of the annealed version, showing that the nominal branching ratio σ converges to unity in the thermodynamic limit, as expected of a self-organized critical system. However, the question remains whether the same results apply to the biological case where only the synapses of firing neurons are depressed (the so-called quenched dynamics). We show that simulations of the quenched model yield significant deviations from σ =1 due to spatial correlations. However, the model is shown to be critical, as the largest eigenvalue of the synaptic matrix approaches unity in the thermodynamic limit, that is, λc=1 . We also study the finite size effects near the critical state as a function of the parameters of the synaptic dynamics.

  2. Population dynamics of sinking phytoplankton in light-limited environments: simulation techniques and critical parameters

    Science.gov (United States)

    Huisman, Jef; Sommeijer, Ben

    2002-10-01

    Phytoplankton use light for photosynthesis, and the light flux decreases with depth. As a result of this simple light dependence, reaction-advection-diffusion models describing the dynamics of phytoplankton species contain an integral over depth. That is, models that simulate phytoplankton dynamics in relation to mixing processes generally have the form of an integro-partial differential equation (integro-PDE). Integro-PDEs are computationally more demanding than standard PDEs. Here, we outline a reliable and efficient technique for numerical simulation of integro-PDEs. The simulation technique is illustrated by several examples on the population dynamics of sinking phytoplankton, using both single-species models and competition models with several phytoplankton species. Our results confirm recent findings that Sverdrup's critical-depth theory breaks down if turbulent mixing is reduced below a critical turbulence. In fact, our results show that suitable conditions for bloom development of sinking phytoplankton depend on a number of critical parameters, including a minimal depth of the thermocline, a maximal depth of the thermocline, a minimal turbulence, and a maximal turbulence. We therefore conclude that models that do not carefully consider the population dynamics of phytoplankton in relation to the turbulence structure of the water column may easily lead to erroneous predictions.

  3. Field theory of bicritical and tetracritical points. IV. Critical dynamics including reversible terms.

    Science.gov (United States)

    Folk, R; Holovatch, Yu; Moser, G

    2012-02-01

    This article concludes a series of papers [Folk, Holovatch, and Moser, Phys. Rev. E 78, 041124 (2008); 78, 041125 (2008); 79, 031109 (2009)] where the tools of the field theoretical renormalization group were employed to explain and quantitatively describe different types of static and dynamic behavior in the vicinity of multicritical points. Here we give the complete two-loop calculation and analysis of the dynamic renormalization-group flow equations at the multicritical point in anisotropic antiferromagnets in an external magnetic field. We find that the time scales of the order parameters characterizing the parallel and perpendicular ordering with respect to the external field scale in the same way. This holds independent whether the Heisenberg fixed point or the biconical fixed point in statics is the stable one. The nonasymptotic analysis of the dynamic flow equations shows that due to cancellation effects the critical behavior is described, in distances from the critical point accessible to experiments, by the critical behavior qualitatively found in one-loop order. Although one may conclude from the effective dynamic exponents (taking almost their one-loop values) that weak scaling for the order parameter components is valid, the flow of the time-scale ratios is quite different, and they do not reach their asymptotic values.

  4. Nonequilibrium critical dynamics of the two-dimensional Ising model quenched from a correlated initial state.

    Science.gov (United States)

    Környei, László; Pleimling, Michel; Iglói, Ferenc

    2008-01-01

    The universality class, even the order of the transition, of the two-dimensional Ising model depends on the range and the symmetry of the interactions (Onsager model, Baxter-Wu model, Turban model, etc.), but the critical temperature is generally the same due to self-duality. Here we consider a sudden change in the form of the interaction and study the nonequilibrium critical dynamical properties of the nearest-neighbor model. The relaxation of the magnetization and the decay of the autocorrelation function are found to display a power law behavior with characteristic exponents that depend on the universality class of the initial state.

  5. Effects of the Hot Alignment of a Power Unit on Oil-Whip Instability Phenomena

    OpenAIRE

    2010-01-01

    This paper shows the results of the analysis of the dynamic behaviour of a power unit, whose shaft-train alignment was significantly influenced by the machine thermal state, that was affected in operating condition by high subsynchronous vibrations caused by oil-whip instability phenomena. The dynamic stiffness coefficients of the oil-film journal bearings of the generator were evaluated considering the critical average journal positions that caused the instability onsets. By including these ...

  6. Critical appraisal of excited state nonadiabatic dynamics simulations of 9H-adeninea)

    Science.gov (United States)

    Barbatti, Mario; Lan, Zhenggang; Crespo-Otero, Rachel; Szymczak, Jaroslaw J.; Lischka, Hans; Thiel, Walter

    2012-12-01

    In spite of the importance of nonadiabatic dynamics simulations for the understanding of ultrafast photo-induced phenomena, simulations based on different methodologies have often led to contradictory results. In this work, we proceed through a comprehensive investigation of on-the-fly surface-hopping simulations of 9H-adenine in the gas phase using different electronic structure theories (ab initio, semi-empirical, and density functional methods). Simulations that employ ab initio and semi-empirical multireference configuration interaction methods predict the experimentally observed ultrafast deactivation of 9H-adenine with similar time scales, however, through different internal conversion channels. Simulations based on time-dependent density functional theory with six different hybrid and range-corrected functionals fail to predict the ultrafast deactivation. The origin of these differences is analyzed by systematic calculations of the relevant reaction pathways, which show that these discrepancies can always be traced back to topographical features of the underlying potential energy surfaces.

  7. Method and apparatus for monitoring dynamic cardiovascular function using n-dimensional representatives of critical functions

    Science.gov (United States)

    Westinskow, Dwayne (Inventor); Agutter, James (Inventor); Syroid, Noah (Inventor); Strayer, David (Inventor); Albert, Robert (Inventor); Wachter, S. Blake (Inventor); Drews, Frank (Inventor)

    2010-01-01

    A method, system, apparatus and device for the monitoring, diagnosis and evaluation of the state of a dynamic pulmonary system is disclosed. This method and system provides the processing means for receiving sensed and/or simulated data, converting such data into a displayable object format and displaying such objects in a manner such that the interrelationships between the respective variables can be correlated and identified by a user. This invention provides for the rapid cognitive grasp of the overall state of a pulmonary critical function with respect to a dynamic system.

  8. The role of disorder in the dynamics of critical fluctuations of mean field models

    CERN Document Server

    Collet, Francesca

    2011-01-01

    The purpose of this paper is to analyze how the disorder affects the dynamics of critical fluctuations for two different types of interacting particle system: the Curie-Weiss and Kuramoto model. The models under consideration are a collection of spins and rotators respectively. They both are subject to a mean field interaction and embedded in a site-dependent, i.i.d. random environment. As the number of particles goes to infinity their limiting dynamics become deterministic and exhibit phase transition. The main result concern the fluctuations around this deterministic limit at the critical point in the thermodynamic limit. From a qualitative point of view, it indicates that when disorder is added spin and rotator systems belong to two different classes of universality, which is not the case for the homogeneous models (i.e., without disorder).

  9. Are Self-Organised Critical Dislocation Dynamics Relevant to Ice Sheet Flow?

    OpenAIRE

    Louchet, François; Duval,Paul; Montagnat, Maurine; Weiss, Jérôme

    2009-01-01

    It was recently shown thai crystals (including ice) plastically deform in an intermittent manner in usual laboratory conditions. The present paper aims at discussing whether such self-organised critical dynamics still apply to polar ice sheet conditions. Field data suggest that grains should contain between zero and one dislocation moving at a time. However, this is nothing but an average estimate. Field data also show that strong back-stresses are present, collesponding to a significant dens...

  10. Dynamical and stationary critical behavior of the Ising ferromagnet in a thermal gradient

    Science.gov (United States)

    Muglia, J.; Albano, E. V.

    2012-08-01

    In this paper we present and discuss results of Monte Carlo numerical simulations of the two-dimensional Ising ferromagnet in contact with a heat bath that intrinsically has a thermal gradient. The extremes of the magnet are at temperatures T 1 T c ) by means of a single simulation. By starting the simulations with fully disordered initial configurations with magnetization m ≡ 0 corresponding to T = ∞, which are then suddenly annealed to a preset thermal gradient, we study the short-time critical dynamic behavior of the system. Also, by setting a small initial magnetization m = m 0, we study the critical initial increase of the order parameter. Furthermore, by starting the simulations from fully ordered configurations, which correspond to the ground state at T = 0 and are subsequently quenched to a preset gradient, we study the critical relaxation dynamics of the system. Additionally, we perform stationary measurements ( t → ∞) that are discussed in terms of the standard finite-size scaling theory. We conclude that our numerical simulation results of the Ising magnet in a thermal gradient, which are rationalized in terms of both dynamic and standard scaling arguments, are fully consistent with well established results obtained under equilibrium conditions.

  11. Dynamical critical behavior of the Ziff-Gulari-Barshad model with quenched impurities

    Science.gov (United States)

    de Andrade, M. F.; Figueiredo, W.

    2016-08-01

    The simplest model to explain the CO oxidation in some catalytic processes is the Ziff-Gulari-Barshad (ZGB) model. It predicts a continuous phase transition between an active phase and an absorbing phase composed of O atoms. By employing Monte Carlo simulations we investigate the dynamical critical behavior of the model as a function of the concentration of fixed impurities over the catalytic surface. By means of an epidemic analysis we calculate the critical exponents related to the survival probability Ps (t), the number of empty sites nv (t), and the mean square displacement R2 (t). We show that the critical exponents depend on the concentration of impurities over the lattice, even for small values of this quantity. We also show that the exponents do not belong to the Directed Percolation universality class and are in agreement with the Harris criterion since the quenched impurities behave as a weak disorder in the system.

  12. Nonequilibrium critical dynamics of the two-dimensional Ashkin-Teller model at the Baxter line

    Science.gov (United States)

    Fernandes, H. A.; da Silva, R.; Caparica, A. A.; de Felício, J. R. Drugowich

    2017-04-01

    We investigate the short-time universal behavior of the two-dimensional Ashkin-Teller model at the Baxter line by performing time-dependent Monte Carlo simulations. First, as preparatory results, we obtain the critical parameters by searching the optimal power-law decay of the magnetization. Thus, the dynamic critical exponents θm and θp, related to the magnetic and electric order parameters, as well as the persistence exponent θg, are estimated using heat-bath Monte Carlo simulations. In addition, we estimate the dynamic exponent z and the static critical exponents β and ν for both order parameters. We propose a refined method to estimate the static exponents that considers two different averages: one that combines an internal average using several seeds with another, which is taken over temporal variations in the power laws. Moreover, we also performed the bootstrapping method for a complementary analysis. Our results show that the ratio β /ν exhibits universal behavior along the critical line corroborating the conjecture for both magnetization and polarization.

  13. Critical phenomena of social complex network

    CERN Document Server

    Genzor, Jozef; Gendiar, Andrej

    2014-01-01

    We propose a multi-state spin model in order to describe equilibrial behavior of a society. Our physical spin system is inspired by the Axelrod model used in social network studies. In the framework of the statistical mechanics language, we analyze phase transitions of our model in which the spin interactions are interpreted as a mutual communication among individuals forming a society. The thermal fluctuations introduce a noise into the communication which suppresses long-range correlations. Below a certain phase transition point, large-scale groups of the individuals, who share a specific dominant property, are formed. The measure of the group sizes is an order parameter after the spontaneous symmetry breaking mechanism has occurred. By means of the Corner transfer matrix renormalization group algorithm, we treat our model in the thermodynamic limit and classify the phase transitions with respect to inherent degrees of freedom. Each individual is chosen to have two independent features and each feature has ...

  14. Criticality in large-scale brain FMRI dynamics unveiled by a novel point process analysis.

    Science.gov (United States)

    Tagliazucchi, Enzo; Balenzuela, Pablo; Fraiman, Daniel; Chialvo, Dante R

    2012-01-01

    Functional magnetic resonance imaging (fMRI) techniques have contributed significantly to our understanding of brain function. Current methods are based on the analysis of gradual and continuous changes in the brain blood oxygenated level dependent (BOLD) signal. Departing from that approach, recent work has shown that equivalent results can be obtained by inspecting only the relatively large amplitude BOLD signal peaks, suggesting that relevant information can be condensed in discrete events. This idea is further explored here to demonstrate how brain dynamics at resting state can be captured just by the timing and location of such events, i.e., in terms of a spatiotemporal point process. The method allows, for the first time, to define a theoretical framework in terms of an order and control parameter derived from fMRI data, where the dynamical regime can be interpreted as one corresponding to a system close to the critical point of a second order phase transition. The analysis demonstrates that the resting brain spends most of the time near the critical point of such transition and exhibits avalanches of activity ruled by the same dynamical and statistical properties described previously for neuronal events at smaller scales. Given the demonstrated functional relevance of the resting state brain dynamics, its representation as a discrete process might facilitate large-scale analysis of brain function both in health and disease.

  15. Universality in the Self Organized Critical behavior of a cellular model of superconducting vortex dynamics

    Science.gov (United States)

    Sun, Yudong; Vadakkan, Tegy; Bassler, Kevin

    2007-03-01

    We study the universality and robustness of variants of the simple model of superconducting vortex dynamics first introduced by Bassler and Paczuski in Phys. Rev. Lett. 81, 3761 (1998). The model is a coarse-grained model that captures the essential features of the plastic vortex motion. It accounts for the repulsive interaction between vortices, the pining of vortices at quenched disordered locations in the material, and the over-damped dynamics of the vortices that leads to tearing of the flux line lattice. We report the results of extensive simulations of the critical ``Bean state" dynamics of the model. We find a phase diagram containing four distinct phases of dynamical behavior, including two phases with distinct Self Organized Critical (SOC) behavior. Exponents describing the avalanche scaling behavior in the two SOC phases are determined using finite-size scaling. The exponents are found to be robust within each phase and for different variants of the model. The difference of the scaling behavior in the two phases is also observed in the morphology of the avalanches.

  16. Static and dynamical critical behavior of the monomer-monomer reaction model with desorption

    Science.gov (United States)

    da Costa, E. C.; Rusch, Flávio Roberto

    2016-06-01

    We studied in this work the monomer-monomer reaction model on a linear chain. The model is described by the following reaction: A + B → AB, where A and B are two monomers that arrive at the surface with probabilities yA and yB, respectively, and we have considered desorption of the monomer B with probability α. The model is studied in the adsorption controlled limit where the reaction rate is infinitely larger than the adsorption rate. We employ site and pair mean-field approximations as well as static and dynamical Monte Carlo simulations. We show that the model exhibits a continuous phase transition between an active steady state and an A-absorbing state, when the parameter yA is varied through a critical value, which depends on the value of α. Monte Carlo simulations and finite-size scaling analysis near the critical point are used to determine the static critical exponents β and ν⊥ and the dynamical critical exponents ν∥ and z. The results found for the monomer-monomer reaction model with B desorption, in the linear chain, are different from those found by E. V. Albano (Albano, 1992) and are in accordance with the values obtained by Jun Zhuo and Sidney Redner (Zhuo and Redner, 1993), and endorse the conjecture of Grassberger, which states that any system undergoing a continuous phase transition from an active steady state to a single absorbing state, exhibits the same critical behavior of the directed percolation universality class.

  17. Study of the critical behavior of the driven lattice gas model with limited nonequilibrium dynamics

    Science.gov (United States)

    Saracco, Gustavo P.; Rubio Puzzo, M. Leticia; Bab, Marisa A.

    2017-02-01

    In this paper the nonequilibrium critical behavior is investigated using a variant of the well-known two-dimensional driven lattice gas (DLG) model, called modified driven lattice gas (MDLG). In this model, the application of the external field is regulated by a parameter p ɛ [ 0 , 1 ] in such a way that if p = 0, the field is not applied, and it becomes the Ising model, while if p = 1, the DLG model is recovered. The behavior of the model is investigated for several values of p by studying the dynamic evolution of the system within the short-time regime in the neighborhood of a phase transition. It is found that the system experiences second-order phase transitions in all the interval of p for the density of particles ρ = 0.5. The determined critical temperatures Tc(p) are greater than the critical temperature of the Ising model TcI, and increase with p up to the critical temperature of the DLG model in the limit of infinite driving fields. The dependence of Tc(p) on p is compatible with a power-law behavior whose exponent is ψ = 0.27(3) . Furthermore, the complete set of the critical and the anisotropic exponents is estimated. For the smallest value of p, the ​dynamics and β exponents are close to that calculated for the Ising model, and the anisotropic exponent Δ is near zero. As p is increased, the exponents and Δ change, meaning that the anisotropy effects increase. For the largest value investigated, the set of exponents approaches to that reported by the most recent theoretical framework developed for the DLG model.

  18. A study of dynamic finite size scaling behavior of the scaling functions—calculation of dynamic critical index of Wolff algorithm

    Science.gov (United States)

    Gündüç, Semra; Dilaver, Mehmet; Aydın, Meral; Gündüç, Yiğit

    2005-02-01

    In this work we have studied the dynamic scaling behavior of two scaling functions and we have shown that scaling functions obey the dynamic finite size scaling rules. Dynamic finite size scaling of scaling functions opens possibilities for a wide range of applications. As an application we have calculated the dynamic critical exponent (z) of Wolff's cluster algorithm for 2-, 3- and 4-dimensional Ising models. Configurations with vanishing initial magnetization are chosen in order to avoid complications due to initial magnetization. The observed dynamic finite size scaling behavior during early stages of the Monte Carlo simulation yields z for Wolff's cluster algorithm for 2-, 3- and 4-dimensional Ising models with vanishing values which are consistent with the values obtained from the autocorrelations. Especially, the vanishing dynamic critical exponent we obtained for d=3 implies that the Wolff algorithm is more efficient in eliminating critical slowing down in Monte Carlo simulations than previously reported.

  19. Inhibitory neurons promote robust critical firing dynamics in networks of integrate-and-fire neurons

    Science.gov (United States)

    Lu, Zhixin; Squires, Shane; Ott, Edward; Girvan, Michelle

    2016-12-01

    We study the firing dynamics of a discrete-state and discrete-time version of an integrate-and-fire neuronal network model with both excitatory and inhibitory neurons. When the integer-valued state of a neuron exceeds a threshold value, the neuron fires, sends out state-changing signals to its connected neurons, and returns to the resting state. In this model, a continuous phase transition from non-ceaseless firing to ceaseless firing is observed. At criticality, power-law distributions of avalanche size and duration with the previously derived exponents, -3 /2 and -2 , respectively, are observed. Using a mean-field approach, we show analytically how the critical point depends on model parameters. Our main result is that the combined presence of both inhibitory neurons and integrate-and-fire dynamics greatly enhances the robustness of critical power-law behavior (i.e., there is an increased range of parameters, including both sub- and supercritical values, for which several decades of power-law behavior occurs).

  20. Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

    Science.gov (United States)

    Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

    2013-09-05

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

  1. Classical dynamics of the Abelian Higgs model from the critical point and beyond

    Directory of Open Access Journals (Sweden)

    G.C. Katsimiga

    2015-09-01

    Full Text Available We present two different families of solutions of the U(1-Higgs model in a (1+1 dimensional setting leading to a localization of the gauge field. First we consider a uniform background (the usual vacuum, which corresponds to the fully higgsed-superconducting phase. Then we study the case of a non-uniform background in the form of a domain wall which could be relevantly close to the critical point of the associated spontaneous symmetry breaking. For both cases we obtain approximate analytical nodeless and nodal solutions for the gauge field resulting as bound states of an effective Pöschl–Teller potential created by the scalar field. The two scenaria differ only in the scale of the characteristic localization length. Numerical simulations confirm the validity of the obtained analytical solutions. Additionally we demonstrate how a kink may be used as a mediator driving the dynamics from the critical point and beyond.

  2. Critical heat flux and dynamics of boiling in nanofluids at stepwise heat release

    Science.gov (United States)

    Moiseev, M. I.; Kuznetsov, D. V.

    2016-10-01

    In this paper results of an experimental study on critical heat flux and dynamics of boiling crisis onset in nanofluids at stepwise heat generation are presented. Freon R21 with three types of nanoparticles - SiO2, Cu and Al2O3 was used as test fluid. Critical heat fluxes and temperatures of boiling initiation were obtained. It was shown that the addition of nanoparticles increased CHF at stepwise heat generation by up to 21%. Under conditions of the experiment transition to film boiling occurred via evaporation fronts. Data on propagation velocity and structure of evaporation fronts were obtained; the spectral analysis of fluctuations of the evaporation front interface was carried out. The characteristic frequencies and amplitudes of interface fluctuations were determined depending on the velocity of evaporation front propagation. It was shown that the addition of nano-sized particles significantly affects development of interface instability and increases the front velocity.

  3. Classical dynamics of the Abelian Higgs model from the critical point and beyond

    Science.gov (United States)

    Katsimiga, G. C.; Diakonos, F. K.; Maintas, X. N.

    2015-09-01

    We present two different families of solutions of the U(1)-Higgs model in a (1 + 1) dimensional setting leading to a localization of the gauge field. First we consider a uniform background (the usual vacuum), which corresponds to the fully higgsed-superconducting phase. Then we study the case of a non-uniform background in the form of a domain wall which could be relevantly close to the critical point of the associated spontaneous symmetry breaking. For both cases we obtain approximate analytical nodeless and nodal solutions for the gauge field resulting as bound states of an effective Pöschl-Teller potential created by the scalar field. The two scenaria differ only in the scale of the characteristic localization length. Numerical simulations confirm the validity of the obtained analytical solutions. Additionally we demonstrate how a kink may be used as a mediator driving the dynamics from the critical point and beyond.

  4. Thermodynamic constraints on fluctuation phenomena

    Science.gov (United States)

    Maroney, O. J. E.

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  5. Transport phenomena in multiphase flows

    CERN Document Server

    Mauri, Roberto

    2015-01-01

    This textbook provides a thorough presentation of the phenomena related to the transport of mass, momentum and energy.  It lays all the basic physical principles, then for the more advanced readers, it offers an in-depth treatment with advanced mathematical derivations and ends with some useful applications of the models and equations in specific settings. The important idea behind the book is to unify all types of transport phenomena, describing them within a common framework in terms of cause and effect, respectively represented by the driving force and the flux of the transported quantity. The approach and presentation are original in that the book starts with a general description of transport processes, providing the macroscopic balance relations of fluid dynamics and heat and mass transfer, before diving into the mathematical realm of continuum mechanics to derive the microscopic governing equations at the microscopic level. The book is a modular teaching tool and can be used either for an introductory...

  6. Thermodynamic constraints on fluctuation phenomena.

    Science.gov (United States)

    Maroney, O J E

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  7. Modeling the Self-organized Critical Behavior of the Plasma Sheet Reconnection Dynamics

    Science.gov (United States)

    Klimas, Alex; Uritsky, Vadim; Baker, Daniel

    2006-01-01

    Analyses of Polar UVI auroral image data reviewed in our other presentation at this meeting (V. Uritsky, A. Klimas) show that bright night-side high-latitude UV emissions exhibit so many of the key properties of systems in self-organized criticality (SOC) that an alternate interpretation has become virtually impossible. It is now necessary to find and model the source of this behavior. We note that the most common models of self-organized criticality are numerical sandpiles. These are, at root, models that govern the transport of some quantity from a region where it is loaded to another where it is unloaded. Transport is enabled by the excitation of a local threshold instability; it is intermittent and bursty, and it exhibits a number of scale-free statistical properties. Searching for a system in the magnetosphere that is analogous and that, in addition, is known to produce auroral signatures, we focus on the reconnection dynamics of the plasma sheet. In our previous work, a driven reconnection model has been constructed and has been under study. The transport of electromagnetic (primarily magnetic) energy carried by the Poynting flux into the reconnection region of the model has been examined. All of the analysis techniques, and more, that have been applied to the auroral image data have also been applied to this Poynting flux. Here, we report new results showing that this model also exhibits so many of the key properties of systems in self-organized criticality that an alternate interpretation is implausible. Further, we find a strong correlation between these key properties of the model and those of the auroral UV emissions. We suggest that, in general, the driven reconnection model is an important step toward a realistic plasma physical model of self-organized criticality and we conclude, more specifically, that it is also a step in the right direction toward modeling the multiscale reconnection dynamics of the magnetotail.

  8. Modeling the Self-organized Critical Behavior of Earth's Plasma Sheet Reconnection Dynamics

    Science.gov (United States)

    Klimas, Alexander J.

    2006-01-01

    Analyses of Polar UVI auroral image data show that bright night-side high-latitude W emissions exhibit so many of the key properties of systems in self-organized criticality that an alternate interpretation has become virtually impossible. These analyses will be reviewed. It is now necessary to find and model the source of this behavior. We note that the most common models of self-organized criticality are numerical sandpiles. These are, at root, models that govern the transport of some quantity from a region where it is loaded to another where it is unloaded. Transport is enabled by the excitation of a local threshold instability; it is intermittent and bursty, and it exhibits a number of scale-free statistical properties. Searching for a system in the magnetosphere that is analogous and that, in addition, is known to produce auroral signatures, we focus on the reconnection dynamics of the magnetotail plasma sheet. In our previous work, a driven reconnection model has been constructed and has been under study. The transport of electromagnetic (primarily magnetic) energy carried by the Poynting flux into the reconnection region of the model has been examined. All of the analysis techniques (and more) that have been applied to the auroral image data have also been applied to this Poynting flux. New results will be presented showing that this model also exhibits so many of the key properties of systems in self-organized criticality that an alternate interpretation is implausible. A strong correlation between these key properties of the model and those of the auroral UV emissions will be demonstrated. We suggest that, in general, the driven reconnection model is an important step toward a realistic plasma physical model of self-organized criticality and we conclude, more specifically, that it is also a step in the right direction toward modeling the multiscale reconnection dynamics of the magnetotail.

  9. Critical transient in the Barab\\'asi model of human dynamics

    CERN Document Server

    Gabrielli, A; Caldarelli, Guido; Gabrielli, Andrea

    2007-01-01

    We introduce an exact probabilistic description for L=2 of the Barab\\'asi model for the dynamics of a list of L tasks. This permits to study the problem out of stationarity, and to solve explicitly the extremal limit case where a critical behavior for the waiting time distribution is observed. This behavior deviates at any finite time from that of the stationary state. We study also the characteristic relaxation time for finite time deviations from stationarity in all cases showing that it diverges in the extremal limit confirming that this deviations are important at all time.

  10. Intermittency at critical transitions and aging dynamics at the onset of chaos

    Indian Academy of Sciences (India)

    A Robledo

    2005-06-01

    We recall that at both the intermittency transitions and the Feigenbaum attractor, in unimodal maps of non-linearity of order > 1, the dynamics rigorously obeys the Tsallis statistics. We account for the -indices and the generalized Lyapunov coefficients that characterize the universality classes of the pitchfork and tangent bifurcations. We identify the Mori singularities in the Lyapunov spectrum at the onset of chaos with the appearance of a special value for the entropic index . The physical area of the Tsallis statistics is further probed by considering the dynamics near criticality and glass formation in thermal systems. In both cases a close connection is made with states in unimodal maps with vanishing Lyapunov coefficients.

  11. Science and Paranormal Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Noyes, H. Pierre

    1999-06-03

    In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ''historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ''paranormal phenomena'' might-but need not- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be defined as contradicting physics.

  12. Nonlinear surface electromagnetic phenomena

    CERN Document Server

    Ponath, H-E

    1991-01-01

    In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are

  13. Science and Paranormal Phenomena

    CERN Document Server

    Noyes, H P

    1999-01-01

    In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ``historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ``paranormal phenomena'' might --- but need not --- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be {\\it defined} as contradicting physics.

  14. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude

    2006-01-01

    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  15. A Critical Review of Dynamic Wetting by Complex Fluids: From Newtonian Fluids to Non-Newtonian Fluids and Nanofluids.

    Science.gov (United States)

    Lu, Gui; Wang, Xiao-Dong; Duan, Yuan-Yuan

    2016-10-01

    Dynamic wetting is an important interfacial phenomenon in many industrial applications. There have been many excellent reviews of dynamic wetting, especially on super-hydrophobic surfaces with physical or chemical coatings, porous layers, hybrid micro/nano structures and biomimetic structures. This review summarizes recent research on dynamic wetting from the viewpoint of the fluids rather than the solid surfaces. The reviewed fluids range from simple Newtonian fluids to non-Newtonian fluids and complex nanofluids. The fundamental physical concepts and principles involved in dynamic wetting phenomena are also reviewed. This review focus on recent investigations of dynamic wetting by non-Newtonian fluids, including the latest experimental studies with a thorough review of the best dynamic wetting models for non-Newtonian fluids, to illustrate their successes and limitations. This paper also reports on new results on the still fledgling field of nanofluid wetting kinetics. The challenges of research on nanofluid dynamic wetting is not only due to the lack of nanoscale experimental techniques to probe the complex nanoparticle random motion, but also the lack of multiscale experimental techniques or theories to describe the effects of nanoparticle motion at the nanometer scale (10(-9) m) on the dynamic wetting taking place at the macroscopic scale (10(-3) m). This paper describes the various types of nanofluid dynamic wetting behaviors. Two nanoparticle dissipation modes, the bulk dissipation mode and the local dissipation mode, are proposed to resolve the uncertainties related to the various types of dynamic wetting mechanisms reported in the literature.

  16. Cole-Cole law for critical dynamics in glass-forming liquids.

    Science.gov (United States)

    Sperl, Matthias

    2006-07-01

    Within the mode-coupling theory (MCT) for glassy dynamics, the asymptotic low-frequency expansions for the dynamical susceptibilities at critical points are compared to the expansions for the dynamic moduli; this shows that the convergence properties of the two expansions can be quite different. In some parameter regions, the leading-order expansion formula for the modulus describes the solutions of the MCT equations of motion outside the transient regime successfully; at the same time, the leading- and next-to-leading-order expansion formulas for the susceptibility fail. In these cases, one can derive a Cole-Cole law for the susceptibilities; and this law accounts for the dynamics for frequencies below the band of microscopic excitations and above the high-frequency part of the alpha peak. It is shown that this scenario explains the optical-Kerr-effect data measured for salol and benzophenone (BZP). For BZP it is inferred that the depolarized light-scattering spectra exhibit a wing for the alpha peak within the Gigahertz band. This wing results from the crossover of the von Schweidler law part of the alpha peak to the high-frequency part of the Cole-Cole peak; and this crossover can be described quantitatively by the leading-order formulas of MCT for the modulus.

  17. Stability and Restoration phenomena in Competitive Systems

    CERN Document Server

    Uechi, Lisa

    2012-01-01

    A conservation law and stability, recovering phenomena and characteristic patterns of a nonlinear dynamical system have been studied and applied to biological and ecological systems. In our previous study, we proposed a system of symmetric 2n-dimensional conserved nonlinear differential equations with external perturbations. In this paper, competitive systems described by 2-dimensional nonlinear dynamical (ND) model with external perturbations are applied to population cycles and recovering phenomena of systems from microbes to mammals. The famous 10-year cycle of population density of Canadian lynx and snowshoe hare is numerically analyzed. We find that a nonlinear dynamical system with a conservation law is stable and generates a characteristic rhythm (cycle) of population density, which we call the {\\it standard rhythm} of a nonlinear dynamical system. The stability and restoration phenomena are strongly related to a conservation law and balance of a system. The {\\it standard rhythm} of population density ...

  18. Dynamic Critical Exponents of Three-Dimensional Ising Models and Two-Dimensional Three-States Potts Models

    Science.gov (United States)

    Murase, Yohsuke; Ito, Nobuyasu

    2008-01-01

    Values of dynamic critical exponents are numerically estimated for various models with the nonequilibrium relaxation method to test the dynamic universality hypothesis. The dynamics used here are single-spin update with Metropolis-type transition probabities. The estimated values of nonequilibrium relaxation exponent of magnetization λm (=β/zν) of Ising models on bcc and fcc lattices are estimated to be 0.251(3) and 0.252(3), respectively, which are consistent with the value of the model on simple-cubic lattice, 0.250(2). The dynamic critical exponents of three-states Potts models on square, honeycomb and triangular lattices are also estimated to be 2.193(5), 2.198(4), and 2.199(3), respectively. They are consistent within the error bars. It is also confirmed that Ising models with regularly modulated coupling constants on square lattice have the same dynamic critical exponents with the uniformly ferromagnetic Ising model.

  19. Study of the nonequilibrium critical quenching and the annealing dynamics for the long-range Ising model in one dimension

    Science.gov (United States)

    Rodriguez, D. E.; Bab, M. A.; Albano, E. V.

    2011-09-01

    Extensive Monte Carlo simulations are employed in order to study the dynamic critical behaviour of the one-dimensional Ising magnet, with algebraically decaying long-range interactions of the form 1/rd + σ, with σ = 0.75. The critical temperature, as well as the critical exponents, are evaluated from the power-law behaviour of suitable physical observables when the system is quenched from uncorrelated states, corresponding to infinite temperature, to the critical point. These results are compared with those obtained from the dynamic evolution of the system when it is annealed at the critical point from the ordered state. Also, the critical temperature in the infinite interaction limit is obtained by means of a finite-range scaling analysis of data measured with different truncated interaction ranges. All the estimated static critical exponents (γ/ν, β/ν, and 1/ν) are in good agreement with renormalization group (RG) results and previously reported numerical data obtained under equilibrium conditions. On the other hand, the dynamic exponent of the initial increase of the magnetization (θ) was close to RG predictions. However, the dynamic exponent z of the time correlation length is slightly different to the RG results probably due to the fact that it may depend on the specific dynamics used or because the two-loop expansion used in the RG analysis may be insufficient.

  20. Complex fission phenomena

    CERN Document Server

    Poenaru, D N; Greiner, W

    2005-01-01

    Complex fission phenomena can be studied in a unified way. Very general reflection asymmetrical equilibrium (saddle-point) nuclear shapes, may be obtained by solving an integro-differential equation without being necessary to specify a certain parametrization. The mass asymmetry in cold fission phenomena can be explained as the result of adding a phenomenological shell correction to the liquid drop model deformation energy. Applications to binary, ternary, and quaternary fission are outlined. Predictions of two alpha accompanied fission are experimentally confirmed.

  1. Nonlinear Photonics and Novel Optical Phenomena

    CERN Document Server

    Morandotti, Roberto

    2012-01-01

    Nonlinear Photonics and Novel Optical Phenomena contains contributed chapters from leading experts in nonlinear optics and photonics, and provides a comprehensive survey of fundamental concepts as well as hot topics in current research on nonlinear optical waves and related novel phenomena. The book covers self-accelerating airy beams, integrated photonics based on high index doped-silica glass, linear and nonlinear spatial beam dynamics in photonic lattices and waveguide arrays, polariton solitons and localized structures in semiconductor microcavities, terahertz waves, and other novel phenomena in different nanophotonic and optical systems.

  2. Computational multi-fluid dynamics predictions of critical heat flux in boiling flow

    Energy Technology Data Exchange (ETDEWEB)

    Mimouni, S., E-mail: stephane.mimouni@edf.fr; Baudry, C.; Guingo, M.; Lavieville, J.; Merigoux, N.; Mechitoua, N.

    2016-04-01

    Highlights: • A new mechanistic model dedicated to DNB has been implemented in the Neptune-CFD code. • The model has been validated against 150 tests. • Neptune-CFD code is a CFD tool dedicated to boiling flows. - Abstract: Extensive efforts have been made in the last five decades to evaluate the boiling heat transfer coefficient and the critical heat flux in particular. Boiling crisis remains a major limiting phenomenon for the analysis of operation and safety of both nuclear reactors and conventional thermal power systems. As a consequence, models dedicated to boiling flows have being improved. For example, Reynolds Stress Transport Model, polydispersion and two-phase flow wall law have been recently implemented. In a previous work, we have evaluated computational fluid dynamics results against single-phase liquid water tests equipped with a mixing vane and against two-phase boiling cases. The objective of this paper is to propose a new mechanistic model in a computational multi-fluid dynamics tool leading to wall temperature excursion and onset of boiling crisis. Critical heat flux is calculated against 150 tests and the mean relative error between calculations and experimental values is equal to 8.3%. The model tested covers a large physics scope in terms of mass flux, pressure, quality and channel diameter. Water and R12 refrigerant fluid are considered. Furthermore, it was found that the sensitivity to the grid refinement was acceptable.

  3. Towards Joint Performance: Building Dynamic Capabilities for Public Critical Asset Maintenance

    Directory of Open Access Journals (Sweden)

    Vesa-Jukka Vornanen

    2014-09-01

    Full Text Available This study aims to present path the joint performance – how the build dynamic capabilities for public critical asset maintenance. The study examined this by finding out the Sand Cone model and Kano model content linkages to the 20 Finnish largest municipality’s Council’s Action Plans (caps. The study overall is based on a case study, supplemented by the content analysis and the survey. Referring to the content analysis of Finnish 20 largest municipalities previous and current Council’s decision-making 2012–2013, a common strategic objective is economic continuity. The case study explains the implementation to conduct multi-focused strategies to the common order fulfilment process. The dynamic capabilities conduct several strategic actions. The study utilized Critical Factor Index analysis to examine network partners. The most significant contributions of the paper are the task of resource allocation to achieving multi-focused strategic goals and an example how the task has been made of.

  4. Analytical description of critical dynamics for two-dimensional dissipative nonlinear maps

    Energy Technology Data Exchange (ETDEWEB)

    Méndez-Bermúdez, J.A. [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, Puebla 72570 (Mexico); Oliveira, Juliano A. de [UNESP – Univ. Estadual Paulista, Câmpus de São João da Boa Vista, Av. Professora Isette Corrêa Fontão, 505, Jardim Santa Rita das Areias, 13876-750 São João da Boa Vista, SP (Brazil); Leonel, Edson D. [Departamento de Física, UNESP – Univ. Estadual Paulista, Av. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste (Italy)

    2016-05-20

    The critical dynamics near the transition from unlimited to limited action diffusion for two families of well known dissipative nonlinear maps, namely the dissipative standard and dissipative discontinuous maps, is characterized by the use of an analytical approach. The approach is applied to explicitly obtain the average squared action as a function of the (discrete) time and the parameters controlling nonlinearity and dissipation. This allows to obtain a set of critical exponents so far obtained numerically in the literature. The theoretical predictions are verified by extensive numerical simulations. We conclude that all possible dynamical cases, independently on the map parameter values and initial conditions, collapse into the universal exponential decay of the properly normalized average squared action as a function of a normalized time. The formalism developed here can be extended to many other different types of mappings therefore making the methodology generic and robust. - Highlights: • We analytically approach scaling properties of a family of two-dimensional dissipative nonlinear maps. • We derive universal scaling functions that were obtained before only approximately. • We predict the unexpected condition where diffusion and dissipation compensate each other exactly. • We find a new universal scaling function that embraces all possible dissipative behaviors.

  5. Short-time critical dynamics of damage spreading in the two-dimensional Ising model

    Science.gov (United States)

    Rubio Puzzo, M. Leticia; Albano, Ezequiel V.

    2010-05-01

    The short-time critical dynamics of propagation of damage in the Ising ferromagnet in two dimensions is studied by means of Monte Carlo simulations. Starting with equilibrium configurations at T=∞ and magnetization M=0 , an initial damage is created by flipping a small amount of spins in one of the two replicas studied. In this way, the initial damage is proportional to the initial magnetization M0 in one of the configurations upon quenching the system at TC , the Onsager critical temperature of the ferromagnetic-paramagnetic transition. It is found that, at short times, the damage increases with an exponent θD=1.915(3) , which is much larger than the exponent θ=0.197 characteristic of the initial increase of the magnetization M(t) . Also, an epidemic study was performed. It is found that the average distance from the origin of the epidemic (⟨R2(t)⟩) grows with an exponent z∗≈η≈1.9 , which is the same, within error bars, as the exponent θD . However, the survival probability of the epidemics reaches a plateau so that δ=0 . On the other hand, by quenching the system to lower temperatures one observes the critical spreading of the damage at TD≃0.51TC , where all the measured observables exhibit power laws with exponents θD=1.026(3) , δ=0.133(1) , and z∗=1.74(3) .

  6. Non-critical string theory formulation of microtubule dynamics and quantum aspects of brain function

    CERN Document Server

    Mavromatos, Nikolaos E

    1995-01-01

    Microtubule (MT) networks, subneural paracrystalline cytosceletal structures, seem to play a fundamental role in the neurons. We cast here the complicated MT dynamics in the form of a 1+1-dimensional non-critical string theory, thus enabling us to provide a consistent quantum treatment of MTs, including enviromental {\\em friction} effects. We suggest, thus, that the MTs are the microsites, in the brain, for the emergence of stable, macroscopic quantum coherent states, identifiable with the {\\em preconscious states}. Quantum space-time effects, as described by non-critical string theory, trigger then an {\\em organized collapse} of the coherent states down to a specific or {\\em conscious state}. The whole process we estimate to take {\\cal O}(1\\,{\\rm sec}), in excellent agreement with a plethora of experimental/observational findings. The {\\em microscopic arrow of time}, endemic in non-critical string theory, and apparent here in the self-collapse process, provides a satisfactory and simple resolution to the age...

  7. 柔性转轴动力学分析与拍振现象%Dynamic Formulations and Beating Phenomena of Rotating Euler-Bernoulli Flexible Shafts

    Institute of Scientific and Technical Information of China (English)

    朱怀亮

    2002-01-01

    In this paper, the intrinsic behavior of rotating Euler-Benoulli flexible shafts was studied due to coupled bending and torsional vibrations. The equations of motion of the shaft with unbalanced eccentricity and viscous material damping were derived by the Hamilton principle. The numerical solution was obtained using the perturbation approach and mode-assuming method. The influences of the coupled vibrations between the bending and torsion, the rotating speed, material damping and the slenderness ratio of the shaft were analyzed. It is clearly shown that the beating phenomena can occur when the interaction of torsion and flexure is considered.

  8. Towards the Verification of Safety-critical Autonomous Systems in Dynamic Environments

    Directory of Open Access Journals (Sweden)

    Adina Aniculaesei

    2016-12-01

    Full Text Available There is an increasing necessity to deploy autonomous systems in highly heterogeneous, dynamic environments, e.g. service robots in hospitals or autonomous cars on highways. Due to the uncertainty in these environments, the verification results obtained with respect to the system and environment models at design-time might not be transferable to the system behavior at run time. For autonomous systems operating in dynamic environments, safety of motion and collision avoidance are critical requirements. With regard to these requirements, Macek et al. [6] define the passive safety property, which requires that no collision can occur while the autonomous system is moving. To verify this property, we adopt a two phase process which combines static verification methods, used at design time, with dynamic ones, used at run time. In the design phase, we exploit UPPAAL to formalize the autonomous system and its environment as timed automata and the safety property as TCTL formula and to verify the correctness of these models with respect to this property. For the runtime phase, we build a monitor to check whether the assumptions made at design time are also correct at run time. If the current system observations of the environment do not correspond to the initial system assumptions, the monitor sends feedback to the system and the system enters a passive safe state.

  9. Holographic Approach to Nonequilibrium Dynamics of Moving Mirrors Coupled to Quantum Critical Theories

    CERN Document Server

    Yeh, Chen-Pin; Lee, Da-Shin

    2013-01-01

    We employ the holographic method to study fluctuations and dissipation of an $n$-dimensional moving mirror coupled to quantum critical theories in $d$ spacetime dimensions. The bulk counterpart of the mirror with perfect reflection is a D$(n+1)$ brane in the Lifshitz geometry of $d+1$ dimensions. The motion of the mirror can be realized from the dynamics of the brane at the boundary of the bulk. The excited modes of the brane in the bulk render the mirror undergoing Brownian motion. For small displacement of the mirror, we derive the analytical results of the correlation functions and response functions. The dynamics of the mirror due to small fluctuations around the brane vacuum state in the bulk is found supraohmic so that after initial growth, the velocity fluctuations approach a saturated value at late time with a power-law behavior. On the contrary, in the Lifshitz black hole background, the mirror in thermal fluctuations shows that its relaxation dynamics becomes ohmic, and the saturation of velocity fl...

  10. Optical feather and foil for shape and dynamic load sensing of critical flight surfaces

    Science.gov (United States)

    Black, Richard J.; Costa, Joannes M.; Faridian, Fereydoun; Moslehi, Behzad; Pakmehr, Mehrdad; Schlavin, Jon; Sotoudeh, Vahid; Zagrai, Andrei

    2014-04-01

    Future flight vehicles may comprise complex flight surfaces requiring coordinated in-situ sensing and actuation. Inspired by the complexity of the flight surfaces on the wings and tail of a bird, it is argued that increasing the number of interdependent flight surfaces from just a few, as is normal in an airplane, to many, as in the feathers of a bird, can significantly enlarge the flight envelope. To enable elements of an eco-inspired Dynamic Servo-Elastic (DSE) flight control system, IFOS is developing a multiple functionality-sensing element analogous to a feather, consisting of a very thin tube with optical fiber based strain sensors and algorithms for deducing the shape of the "feather" by measuring strain at multiple points. It is envisaged that the "feather" will act as a unit of sensing and/or actuation for establishing shape, position, static and dynamic loads on flight surfaces and in critical parts. Advanced sensing hardware and software control algorithms will enable the proposed DSE flight control concept. The hardware development involves an array of optical fiber based sensorized needle tubes for attachment to key parts for dynamic flight surface measurement. Once installed the optical fiber sensors, which can be interrogated over a wide frequency range, also allow damage detection and structural health monitoring.

  11. Complex Dynamics of the Power Transmission Grid (and other Critical Infrastructures)

    Science.gov (United States)

    Newman, David

    2015-03-01

    Our modern societies depend crucially on a web of complex critical infrastructures such as power transmission networks, communication systems, transportation networks and many others. These infrastructure systems display a great number of the characteristic properties of complex systems. Important among these characteristics, they exhibit infrequent large cascading failures that often obey a power law distribution in their probability versus size. This power law behavior suggests that conventional risk analysis does not apply to these systems. It is thought that much of this behavior comes from the dynamical evolution of the system as it ages, is repaired, upgraded, and as the operational rules evolve with human decision making playing an important role in the dynamics. In this talk, infrastructure systems as complex dynamical systems will be introduced and some of their properties explored. The majority of the talk will then be focused on the electric power transmission grid though many of the results can be easily applied to other infrastructures. General properties of the grid will be discussed and results from a dynamical complex systems power transmission model will be compared with real world data. Then we will look at a variety of uses of this type of model. As examples, we will discuss the impact of size and network homogeneity on the grid robustness, the change in risk of failure as generation mix (more distributed vs centralized for example) changes, as well as the effect of operational changes such as the changing the operational risk aversion or grid upgrade strategies. One of the important outcomes from this work is the realization that ``improvements'' in the system components and operational efficiency do not always improve the system robustness, and can in fact greatly increase the risk, when measured as a risk of large failure.

  12. The role of heterogeneities as a tuning parameter of earthquake dynamics in relation to criticality

    Science.gov (United States)

    Zoeller, G.; Holschneider, M.; Ben-Zion, Y.

    2003-12-01

    We investigate the influence of spatial heterogeneities on various aspects of seismicity in a single-fault model. The model dynamics is governed by realistic boundary conditions consisting of constant velocity motion of regions around the fault, static/kinetic friction laws, creep with depth-dependent coefficients as in Ben-Zion (JGR 101, 1996), and 3D elastic stress transfer based on the solution of Chinnery (1963). The dynamic rupture is approximated on a continuous time scale using a finite stress propagation velocity (``quasi-dynamic model''). The model produces a ``brittle-ductile'' transition at a depth of about 12.5 km, realistic hypocenter distributions, and other features of seismicity compatible with observations. Ben-Zion et al. (JGR 108, 2003) suggested that the range of size scales in the distribution of strength-stress heterogeneities acts as a tuning parameter of dynamics, and that the evolution of this parameter in large earthquake cycles produces intermittent criticality. Here we test this hypothesis by performing a systematic parameter-space study with different forms of heterogeneities. In particular, we analyse spatial heterogeneities that can be tuned by a single parameter in two distributions: (1) a set of circular asperities with a different stress drop and variable range of radii and (2) spatial heterogeneities with fractal properties and variable fractal dimension. We analyze the influence of the tuning parameter of the heterogeneities on different measures of seismicity and discuss the results in terms of the phase diagram approach of Dahmen et al. (Phys. Rev. E 58, 1998).

  13. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  14. Modelling of density limit phenomena in toroidal helical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, K. [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, S.-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Giannone, L. [Max Planck Institut fuer Plasmaphysik, EURATOM-IPP Association, Garching (Germany)

    2000-03-01

    The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the W7-AS stellarator. (author)

  15. Modelling of density limit phenomena in toroidal helical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Giannone, Louis [EURATOM-IPP Association, Max Planck Institut fuer Plasmaphysik, Garching (Germany)

    2001-11-01

    The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the Wendelstein 7-AS (W7-AS) stellarator. (author)

  16. Rheological phenomena in focus

    CERN Document Server

    Boger, DV

    1993-01-01

    More than possibly any other scientific discipline, rheology is easily visualized and the relevant literature contains many excellent photographs of unusual and often bizarre phenomena. The present book brings together these photographs for the first time. They are supported by a full explanatory text. Rheological Phenomena in Focus will be an indispensable support manual to all those who teach rheology or have to convince colleagues of the practical relevance of the subject within an industrial setting. For those who teach fluid mechanics, the book clearly illustrates the difference be

  17. Wave phenomena in sunspots

    Science.gov (United States)

    Löhner-Böttcher, Johannes

    2016-03-01

    Context: The dynamic atmosphere of the Sun exhibits a wealth of magnetohydrodynamic (MHD) waves. In the presence of strong magnetic fields, most spectacular and powerful waves evolve in the sunspot atmosphere. Allover the sunspot area, continuously propagating waves generate strong oscillations in spectral intensity and velocity. The most prominent and fascinating phenomena are the 'umbral flashes' and 'running penumbral waves' as seen in the sunspot chromosphere. Their nature and relation have been under intense discussion in the last decades. Aims: Waves are suggested to propagate upward along the magnetic field lines of sunspots. An observational study is performed to prove or disprove the field-guided nature and coupling of the prevalent umbral and penumbral waves. Comprehensive spectroscopic observations at high resolution shall provide new insights into the wave characteristics and distribution across the sunspot atmosphere. Methods: Two prime sunspot observations were carried out with the Dunn Solar Telescope at the National Solar Observatory in New Mexico and with the Vacuum Tower Telescope at the Teide Observatory on Tenerife. The two-dimensional spectroscopic observations were performed with the interferometric spectrometers IBIS and TESOS. Multiple spectral lines are scanned co-temporally to sample the dynamics at the photospheric and chromospheric layers. The time series (1 - 2.5 h) taken at high spatial and temporal resolution are analyzed according to their evolution in spectral intensities and Doppler velocities. A wavelet analysis was used to obtain the wave power and dominating wave periods. A reconstruction of the magnetic field inclination based on sunspot oscillations was developed. Results and conclusions: Sunspot oscillations occur continuously in spectral intensity and velocity. The obtained wave characteristics of umbral flashes and running penumbral waves strongly support the scenario of slow-mode magnetoacoustic wave propagation along the

  18. Quantum Critical Dynamics of Bose-Einstein Condensates in a Shaken Optical Lattice

    Science.gov (United States)

    Clark, Logan W.; Feng, Lei; Ha, Li-Chung; Chin, Cheng

    2016-05-01

    From condensed matter to cosmology, systems which cross a continuous, symmetry-breaking phase transition are expected to generate topological defects whose density scales universally with the rate at which the phase transition is crossed. We experimentally test the application of this universal Kibble-Zurek scaling prediction to quantum phase transitions by studying ultracold bosons in a shaken optical lattice. When the lattice shaking amplitude crosses a critical threshold, an ordinary Bose condensate transitions to an effectively ferromagnetic pseudo-spinor condensate with discrete, magnetized regions separated by domain walls. We appraise the dynamic scaling laws for both the time at which the domain structure forms and the typical size of the domains by varying the quench rate across the transition. We explore the regime in which the universal prediction applies, as well as potential deviations at extreme quench rates.

  19. Critical exponents of dynamical conductivity in 2D percolative superconductor-insulator transitions: three universality classes.

    Science.gov (United States)

    Karki, Pragalv; Loh, Yen Lee

    2016-11-02

    We simulate three types of random inductor-capacitor (LC) networks on [Formula: see text] square lattices. We calculate the dynamical conductivity using an equation-of-motion method in which timestep error is eliminated and windowing error is minimized. We extract the critical exponent a such that [Formula: see text] at low frequencies. The results suggest that there are three different universality classes. The [Formula: see text] model, with capacitances from each site to ground, has a  =  0.314(4). The [Formula: see text] model, with capacitances along bonds, has a  =  0. The [Formula: see text] model, with both types of capacitances, has a  =  0.304(1). This implies that classical percolative 2D superconductor-insulator transitions (SITs) generically have [Formula: see text] as [Formula: see text]. Therefore, any experiments that give a constant conductivity as [Formula: see text] must be explained in terms of quantum effects.

  20. Possible Self-Organised Criticality and Dynamical Clustering of Traffic flow in Open Systems

    CERN Document Server

    Larraga, M E; Mehta, A; Mehta, Anita

    1999-01-01

    We focus in this work on the study of traffic in open systems using a modified version of an existing cellular automaton model. We demonstrate that the open system is rather different from the closed system in its 'choice' of a unique steady-state density and velocity distribution, independently of the initial conditions, reminiscent of self-organised criticality. Quantities of interest such as average densities and velocities of cars, exhibit phase transitions between free flow and the jammed state, as a function of the braking probability R in a way that is very different from closed systems. Velocity correlation functions show that the concept of a dynamical cluster, introduced earlier in the context of granular flow is also relevant for traffic flow models.

  1. Synchronization Phenomena in Coupled Colpitts Circuits

    Directory of Open Access Journals (Sweden)

    Ch. K. Volos

    2014-11-01

    Full Text Available In this work, the case of coupling (bidirectional and unidirectional between two identical nonlinear chaotic circuits via a linear resistor, is studied. The produced dynamical systems have different structure, in regard to other similar works, due to the choice of coupling nodes. As a circuit, a modification of the most well-known nonlinear circuit that can operate in a wide range of radiofrequencies, the Colpitts oscillator, is chosen. The simulation and the experimental results show a variety of dynamical phenomena, such as periodic, quasi-periodic and chaotic behaviors, as well as anti-phase and complete synchronization phenomena, depending on the value of the coupling coefficient.

  2. Towards a dynamic assessment of raw materials criticality: linking agent-based demand--with material flow supply modelling approaches.

    Science.gov (United States)

    Knoeri, Christof; Wäger, Patrick A; Stamp, Anna; Althaus, Hans-Joerg; Weil, Marcel

    2013-09-01

    Emerging technologies such as information and communication-, photovoltaic- or battery technologies are expected to increase significantly the demand for scarce metals in the near future. The recently developed methods to evaluate the criticality of mineral raw materials typically provide a 'snapshot' of the criticality of a certain material at one point in time by using static indicators both for supply risk and for the impacts of supply restrictions. While allowing for insights into the mechanisms behind the criticality of raw materials, these methods cannot account for dynamic changes in products and/or activities over time. In this paper we propose a conceptual framework intended to overcome these limitations by including the dynamic interactions between different possible demand and supply configurations. The framework integrates an agent-based behaviour model, where demand emerges from individual agent decisions and interaction, into a dynamic material flow model, representing the materials' stocks and flows. Within the framework, the environmental implications of substitution decisions are evaluated by applying life-cycle assessment methodology. The approach makes a first step towards a dynamic criticality assessment and will enhance the understanding of industrial substitution decisions and environmental implications related to critical metals. We discuss the potential and limitation of such an approach in contrast to state-of-the-art methods and how it might lead to criticality assessments tailored to the specific circumstances of single industrial sectors or individual companies. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Critical state and vortex dynamics in high temperature superconductors: Experimental and numerical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Gjoelmesli, S.

    1995-05-01

    In this thesis, statics and dynamics of magnetic vortices in high temperature superconductors has been investigated by ac susceptibility, magnetic relaxation and transport measurements, using several different compounds. Measurements of the complex susceptibility of granular superconducting YBa{sub 2}Cu{sub 3}O{sub 7{sub -}x} (YBCO) reveal two distinct regimes of screening due to granular and intergranular currents respectively. In the critical state, the presence of a dc field breaks the symmetry of the experimental conditions if the critical current is field dependent. In such experiments two peaks in the loss component {chi}{sup ``}(B) of the complex susceptibility are found, both caused by intergranular currents. The symmetry breaking due to a dc field is seen directly in sampled waveforms of the pickup coil voltage, which represent the time derivative of the dynamic magnetization. In contrast to granular materials, a single crystal YBCO displays significant frequency dependence of the peak of the loss component {chi}{sup ``}(T). The power-law voltage current characteristic is equivalent to nonlinear vortex diffusion, with a characteristic length scale which reduces to the Bean depth and the classical skin-depth as the exponent tends to infinity and one, respectively. Magnetic relaxation measurements on the mercury based superconductor Hg-1212 has been done by means of a SQUID magnetometer. A new set-up for measurements of voltage-current characteristics of superconducting tapes and other samples has been constructed. Silver sheathed Bi-2223 tapes have been measured. 123 refs., 61 figs., 1 tab.

  4. Exploring glacier dynamics with subglacial water pressure pulses: Evidence for self-organized criticality?

    Science.gov (United States)

    Kavanaugh, J. L.

    2009-03-01

    In order to determine whether brief excursions, or "pulses," in subglacial water pressure inferred by Kavanaugh and Clarke (2000, 2001) occur, water pressures at the bed of Trapridge Glacier, Yukon, Canada, were recorded using an interface board that continuously monitored a pressure transducer. During the 231 day period between 16 July 2005 and 4 March 2006, more than 7000 pressure pulses were recorded, with magnitudes reaching nearly 3 times the flotation value. Comparison of the pressure pulse record with those from a number of other instruments installed in this soft-bedded glacier indicates that these pulses are generated by stress transients that compress the water within the borehole; calculations suggest that these transients are as large as 75 times the nominal driving stress. Both the magnitudes and interevent times for these pulses are well fitted by power law distributions that are remarkably similar to those exhibited by earthquakes. These similarities suggest that the ice-bed interface of a soft-bedded glacier behaves much like an earthquake fault and raises the possibility that such glaciers self-organize to a critical state. Further evidence for self-organized criticality (SOC) of soft-bedded glaciers is suggested by an examination of well-known ice dynamical properties and the rheological properties of subglacial sediments, which suggests that SOC might be a natural consequence of the rate-independent behavior of subglacial sediments.

  5. Bioelectrochemistry II membrane phenomena

    CERN Document Server

    Blank, M

    1987-01-01

    This book contains the lectures of the second course devoted to bioelectro­ chemistry, held within the framework of the International School of Biophysics. In this course another very large field of bioelectrochemistry, i. e. the field of Membrane Phenomena, was considered, which itself consists of several different, but yet related subfields. Here again, it can be easily stated that it is impossible to give a complete and detailed picture of all membrane phenomena of biological interest in a short course of about one and half week. Therefore the same philosophy, as the one of the first course, was followed, to select a series of lectures at postgraduate level, giving a synthesis of several membrane phenomena chosen among the most'important ones. These lectures should show the large variety of membrane-regulated events occurring in living bodies, and serve as sound interdisciplinary basis to start a special­ ized study of biological phenomena, for which the investigation using the dual approach, physico-che...

  6. Critical transitions of stratocumulus dynamical systems due to perturbation in free-atmosphere moisture

    Science.gov (United States)

    Tsai, Jia-Ying; Wu, Chien-Ming

    2016-12-01

    The bi-stable behavior of stratocumulus systems is here investigated in a 3D cloud-resolving model based on vector vorticity equations (VVM). This study demonstrates the response of the stratocumulus system to small perturbations of free atmospheric moisture under specified forcings of warm sea surface temperature (SST) and weak subsidence. A critical transition, indicated by the strong decoupling and large variation of cloud properties, separates fast dynamics from slow dynamics. During the fast process governed by the thermodynamic adjustment, the liquid water path (LWP) decreases with a decreasing cloud-top entrainment rate; on the other hand, during the slow process determined by the cloud-top inversion adjustment, LWP increases. The model exhibits two coexisting (cloudy and non-cloudy) quasi-stationary states through the fast process. A key process for the bifurcation is that the non-cloudy state shows the presence of active cumulus convection that allows the destruction of stratocumulus. The results suggest that the direct entrainment drying is enhanced due to an increased moisture gradient across the inversion layer. This tends to develop more broken clouds, which is an important signal for the stratocumulus to cumulus transition. This conceptual model provides a simple framework for developing a timely switch of regime transition in the cloud parameterization in large-scale models.

  7. Toward an improved understanding of the role of transpiration in critical zone dynamics

    Science.gov (United States)

    Mitra, B.; Papuga, S. A.

    2012-12-01

    Evapotranspiration (ET) is an important component of the total water balance across any ecosystem. In subalpine mixed-conifer ecosystems, transpiration (T) often dominates the total water flux and therefore improved understanding of T is critical for accurate assessment of catchment water balance and for understanding of the processes that governs the complex dynamics across critical zone (CZ). The interaction between T and plant vegetation not only modulates soil water balance but also influences water transit time and hydrochemical flux - key factors in our understanding of how the CZ evolves and responds. Unlike an eddy covariance system which provides only an integrated ET flux from an ecosystem, a sap flow system can provide an estimate of the T flux from the ecosystem. By isolating T, the ecohydrological drivers of this major water loss from the CZ can be identified. Still, the species composition of mixed-conifer ecosystems vary and the drivers of T associated with each species are expected to be different. Therefore, accurate quantification of T from a mixed-conifer requires knowledge of the unique transpiration dynamics of each of the tree species. Here, we installed a sap flow system within two mixed-conifer study sites of the Jemez River Basin - Santa Catalina Mountains Critical Zone Observatory (JRB - SCM CZO). At both sites, we identified the dominant tree species and installed sap flow sensors on healthy representatives for each of those species. At the JRB CZO site, sap sensors were installed in fir (4) and spruce (4) trees; at the SCM CZO site, sap sensors were installed at white fir (4) and maple (4) and one dead tree. Meteorological data as well as soil temperature (Ts) and soil moisture (θ) at multiple depths were also collected from each of the two sites. Preliminary analysis of two years of sap flux rate at JRB - SCM CZO shows that the environmental drivers of fir, spruce, and maple are different and also vary throughout the year. For JRB fir

  8. DMPD: IRAK1: a critical signaling mediator of innate immunity. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17890055 IRAK1: a critical signaling mediator of innate immunity. Gottipati S, Rao ...IRAK1: a critical signaling mediator of innate immunity. PubmedID 17890055 Title IRAK1: a critical signaling media

  9. Density functional approaches to collective phenomena in nuclei: Time-dependent density-functional theory for perturbative and non-perturbative nuclear dynamics

    CERN Document Server

    Nakatsukasa, Takashi

    2012-01-01

    We present the basic concepts and our recent developments in the density functional approaches with the Skyrme functionals for describing nuclear dynamics at low energy. The time-dependent density-functional theory (TDDFT) is utilized for the exact linear response with an external perturbation. For description of collective dynamics beyond the perturbative regime, we present a theory of a decoupled collective submanifold to describe for a slow motion based on the TDDFT. Selected applications are shown to demonstrate the quality of their performance and feasibility. Advantages and disadvantages in the numerical aspects are also discussed.

  10. A CRITICAL ANALYSIS OF THE IMPACT OF CLASSROOM DYNAMICS ON STUDENTS' SOCIAL INTERACTION IN SECONDARY SCHOOLS IN KENYA

    OpenAIRE

    Mercy Ngugi; Ruth W. Thinguri

    2017-01-01

    The purpose of the study was a critical analysis of the impact of classroom dynamics on students’ social interaction in secondary schools in Kenya. Most of the Kenyan secondary schools are faced with the challenge of overcrowding in the classrooms thus unsuited to providing a positive classroom atmosphere hence limited leaner-teacher contact. The critical analysis was to establish and address issues and strategies that must be implemented to create a positive classroom atmosphere where learne...

  11. Dynamic Critical Behavior of Multi-Grid Monte Carlo for Two-Dimensional Nonlinear $\\sigma$-Models

    OpenAIRE

    Mana, Gustavo; Mendes, Tereza; Pelissetto, Andrea; Sokal, Alan D.

    1995-01-01

    We introduce a new and very convenient approach to multi-grid Monte Carlo (MGMC) algorithms for general nonlinear $\\sigma$-models: it is based on embedding an $XY$ model into the given $\\sigma$-model, and then updating the induced $XY$ model using a standard $XY$-model MGMC code. We study the dynamic critical behavior of this algorithm for the two-dimensional $O(N)$ $\\sigma$-models with $N = 3,4,8$ and for the $SU(3)$ principal chiral model. We find that the dynamic critical exponent $z$ vari...

  12. Sustainability from the Occurrence of Critical Dynamic Power System Blackout Determined by Using the Stochastic Event Tree Technique

    Directory of Open Access Journals (Sweden)

    Muhammad Murtadha Othman

    2017-06-01

    Full Text Available With the advent of advanced technology in smart grid, the implementation of renewable energy in a stressed and complicated power system operation, aggravated by a competitive electricity market and critical system contingencies, this will inflict higher probabilities of the occurrence of a severe dynamic power system blackout. This paper presents the proposed stochastic event tree technique used to assess the sustainability against the occurrence of dynamic power system blackout emanating from implication of critical system contingencies such as the rapid increase in total loading condition and sensitive initial transmission line tripping. An extensive analysis of dynamic power system blackout has been carried out in a case study of the following power systems: IEEE RTS-79 and IEEE RTS-96. The findings have shown that the total loading conditions and sensitive transmission lines need to be given full attention by the utility to prevent the occurrence of dynamic power system blackout.

  13. Neutron spin-echo study of the critical dynamics of spin-5/2 antiferromagnets in two and three dimensions

    Science.gov (United States)

    Tseng, K. F.; Keller, T.; Walters, A. C.; Birgeneau, R. J.; Keimer, B.

    2016-07-01

    We report a neutron spin-echo study of the critical dynamics in the S =5/2 antiferromagnets MnF2 and Rb2MnF4 with three-dimensional (3D) and two-dimensional (2D) spin systems, respectively, in zero external field. Both compounds are Heisenberg antiferromagnets with a small uniaxial anisotropy resulting from dipolar spin-spin interactions, which leads to a crossover in the critical dynamics close to the Néel temperature, TN. By taking advantage of the μ eV energy resolution of the spin-echo spectrometer, we have determined the dynamical critical exponents z for both longitudinal and transverse fluctuations. In MnF2, both the characteristic temperature for crossover from 3D Heisenberg to 3D Ising behavior and the exponents z in both regimes are consistent with predictions from the dynamical scaling theory. The amplitude ratio of longitudinal and transverse fluctuations also agrees with predictions. In Rb2MnF4 , the critical dynamics crosses over from the expected 2D Heisenberg behavior for T ≫TN to a scaling regime with exponent z =1.387 (4 ) , which has not been predicted by theory and may indicate the influence of long-range dipolar interactions.

  14. Fluid Physical and Transport Phenomena Studies aboard the International Space Station: Planned Experiments

    Science.gov (United States)

    Singh, Bhim S.

    1999-01-01

    This paper provides an overview of the microgravity fluid physics and transport phenomena experiments planned for the International Spare Station. NASA's Office of Life and Microgravity Science and Applications has established a world-class research program in fluid physics and transport phenomena. This program combines the vast expertise of the world research community with NASA's unique microgravity facilities with the objectives of gaining new insight into fluid phenomena by removing the confounding effect of gravity. Due to its criticality to many terrestrial and space-based processes and phenomena, fluid physics and transport phenomena play a central role in the NASA's Microgravity Program. Through widely publicized research announcement and well established peer-reviews, the program has been able to attract a number of world-class researchers and acquired a critical mass of investigations that is now adding rapidly to this field. Currently there arc a total of 106 ground-based and 20 candidate flight principal investigators conducting research in four major thrust areas in the program: complex flows, multiphase flow and phase change, interfacial phenomena, and dynamics and instabilities. The International Space Station (ISS) to be launched in 1998, provides the microgravity research community with a unprecedented opportunity to conduct long-duration microgravity experiments which can be controlled and operated from the Principal Investigators' own laboratory. Frequent planned shuttle flights to the Station will provide opportunities to conduct many more experiments than were previously possible. NASA Lewis Research Center is in the process of designing a Fluids and Combustion Facility (FCF) to be located in the Laboratory Module of the ISS that will not only accommodate multiple users but, allow a broad range of fluid physics and transport phenomena experiments to be conducted in a cost effective manner.

  15. Shock wave reflection phenomena

    CERN Document Server

    Ben-dor, Gabi

    2007-01-01

    This book provides a comprehensive state-of-the-knowledge description of the shock wave reflection phenomena from a phenomenological point of view. The first part is a thorough introduction to oblique shock wave reflections, presenting the two major well-known reflection wave configurations, namely, regular (RR) and Mach (MR) reflections, the corresponding two- and three-shock theories, their analytical and graphical solution and the proposed transition boundaries between these two reflection-wave configurations. The second, third and fourth parts describe the reflection phenomena in steady, pseudo-steady and unsteady flows, respectively. Here, the possible specific types of reflection wave configurations are described, criteria for their formation and termination are presented and their governing equations are solved analytically and graphically and compared with experimental results. The resolution of the well-known von Neumann paradox and a detailed description of two new reflection-wave configurations - t...

  16. Complex fission phenomena

    Science.gov (United States)

    Poenaru, D. N.; Gherghescu, R. A.; Greiner, W.

    2005-01-01

    Complex fission phenomena are studied in a unified way. Very general reflection asymmetrical equilibrium (saddle point) nuclear shapes are obtained by solving an integro-differential equation without being necessary to specify a certain parametrization. The mass asymmetry in binary cold fission of Th and U isotopes is explained as the result of adding a phenomenological shell correction to the liquid drop model deformation energy. Applications to binary, ternary, and quaternary fission are outlined.

  17. Membrane Transport Phenomena (MTP)

    Science.gov (United States)

    Mason, Larry W.

    1997-01-01

    The third semi-annual period of the MTP project has been involved with performing experiments using the Membrane Transport Apparatus (MTA), development of analysis techniques for the experiment results, analytical modeling of the osmotic transport phenomena, and completion of a DC-9 microgravity flight to test candidate fluid cell geometries. Preparations were also made for the MTP Science Concept Review (SCR), held on 13 June 1997 at Lockheed Martin Astronautics in Denver. These activities are detailed in the report.

  18. Transport phenomena in porous media

    CERN Document Server

    Ingham, Derek B

    1998-01-01

    Research into thermal convection in porous media has substantially increased during recent years due to its numerous practical applications. These problems have attracted the attention of industrialists, engineers and scientists from many very diversified disciplines, such as applied mathematics, chemical, civil, environmental, mechanical and nuclear engineering, geothermal physics and food science. Thus, there is a wealth of information now available on convective processes in porous media and it is therefore appropriate and timely to undertake a new critical evaluation of this contemporary information. Transport Phenomena in Porous Media contains 17 chapters and represents the collective work of 27 of the world's leading experts, from 12 countries, in heat transfer in porous media. The recent intensive research in this area has substantially raised the expectations for numerous new practical applications and this makes the book a most timely addition to the existing literature. It includes recent major deve...

  19. Paramutation phenomena in plants.

    Science.gov (United States)

    Pilu, Roberto

    2015-08-01

    Paramutation is a particular epigenetic phenomenon discovered in Zea mays by Alexander Brink in the 1950s, and then also found in other plants and animals. Brink coined the term paramutation (from the Greek syllable "para" meaning beside, near, beyond, aside) in 1958, with the aim to differentiate paramutation from mutation. The peculiarity of paramutation with respect to other gene silencing phenomena consists in the ability of the silenced allele (named paramutagenic) to silence the other allele (paramutable) present in trans. The newly silenced (paramutated) allele remains stable in the next generations even after segregation from the paramutagenic allele and acquires paramutagenic ability itself. The inheritance behaviour of these epialleles permits a fast diffusion of a particular gene expression level/phenotype in a population even in the absence of other evolutionary influences, thus breaking the Hardy-Weinberg law. As with other gene silencing phenomena such as quelling in the fungus Neurospora crassa, transvection in Drosophila, co-suppression and virus-induced gene silencing (VIGS) described in transgenic plants and RNA interference (RNAi) in the nematode Caenorhabditis elegans, paramutation occurs without changes in the DNA sequence. So far the molecular basis of paramutation remains not fully understood, although many studies point to the involvement of RNA causing changes in DNA methylation and chromatin structure of the silenced genes. In this review I summarize all paramutation phenomena described in plants, focusing on the similarities and differences between them.

  20. Soil water storage, mixing dynamics and resulting travel times through the critical zone in northern latitudes

    Science.gov (United States)

    Sprenger, Matthias; Tetzlaff, Doerthe; Weiler, Markus; Soulsby, Chris

    2017-04-01

    Water partitioning in the unsaturated zone into groundwater recharge, plant transpiration, and evaporation is fundamental for estimating storages and travel times. How water is mixed and routed through the soil is of broad interest to understand plant available water, contamination transport and weathering rates in the critical zone. Earlier work has shown how seasonal changes in hydroclimate influence the time variant character of travel times. A strong seasonality characterizes the northern latitudes which are particularly sensitive to climate and land use changes. It is crucial to understand how variation and change in hydroclimate and vegetation phenology impact time variant storage dynamics and flow path partitioning in the unsaturated zone. To better understand the influence of these ecohydrological processes on travel times of evaporative, transpiration and recharge fluxes in northern latitudes, we characterized soil physical properties, hydrometric conditions and soil water isotopic composition in the upper soil profile in two different land scape units in the long term experimental catchment, Bruntland Burn in the Scottish Highlands. Our two sampling locations are characterized by podzol soils with high organic matter content but they differ with regard to their vegetation cover with either Scots Pine (Pinus sylvestris) or heather (Calluna sp. and Erica Sp). To assess storage and mixing dynamics in the vadose zone, we parameterized a numerical 1-D flow model using the soil textural information along with soil moisture and soil water stable isotopes (δ2H and δ18O). The water flow and transport were simulated based on the Richards and the advection dispersion equation. Differences between water flows of mobile and tightly bound soil waters and the mixing between the two pore spaces were considered. Isotopic fractionation due to evaporation from soil and interception storage was taken into account, while plant water uptake did not alter the isotopic

  1. Global properties of symmetric competition models with riddling and blowout phenomena

    Directory of Open Access Journals (Sweden)

    Giant-italo Bischi

    2000-01-01

    Full Text Available In this paper the problem of chaos synchronization, and the related phenomena of riddling, blowout and on–off intermittency, are considered for discrete time competition models with identical competitors. The global properties which determine the different effects of riddling and blowout bifurcations are studied by the method of critical curves, a tool for the study of the global dynamical properties of two-dimensional noninvertible maps. These techniques are applied to the study of a dynamic market-share competition model.

  2. Interference Phenomena in Quantum Information

    CERN Document Server

    Stefanak, Martin

    2010-01-01

    One of the key features of quantum mechanics is the interference of probability amplitudes. The reason for the appearance of interference is mathematically very simple. It is the linear structure of the Hilbert space which is used for the description of quantum systems. In terms of physics we usually talk about the superposition principle valid for individual and composed quantum objects. So, while the source of interference is understandable it leads in fact to many counter-intuitive physical phenomena which puzzle physicists for almost hundred years. The present thesis studies interference in two seemingly disjoint fields of physics. However, both have strong links to quantum information processing and hence are related. In the first part we study the intriguing properties of quantum walks. In the second part we analyze a sophisticated application of wave packet dynamics in atoms and molecules for factorization of integers. The main body of the thesis is based on the original contributions listed separately...

  3. Critical analysis of the current approaches to modelling educational effectiveness : The importance of establishing a dynamic model

    NARCIS (Netherlands)

    Creemers, B. P. M.; Kyriakides, L.

    2006-01-01

    Researchers in the area of educational effectiveness should attempt to develop a new theoretical framework. A critical analysis of the current models of educational effectiveness research is provided and reveals that a dynamic model of effectiveness must: (a) be multilevel in nature, (b) be based on

  4. Critical exponents of dynamical conductivity in 2D percolative superconductor-insulator transitions: three universality classes

    Science.gov (United States)

    Karki, Pragalv; Loh, Yen Lee

    2016-11-01

    We simulate three types of random inductor-capacitor (LC) networks on 6000× 6000 square lattices. We calculate the dynamical conductivity using an equation-of-motion method in which timestep error is eliminated and windowing error is minimized. We extract the critical exponent a such that σ ≤ft(ω \\right)\\propto {ω-a} at low frequencies. The results suggest that there are three different universality classes. The {{L}ij}{{C}i} model, with capacitances from each site to ground, has a  =  0.314(4). The {{L}ij}{{C}ij} model, with capacitances along bonds, has a  =  0. The {{L}ij}{{C}i}{{C}ij} model, with both types of capacitances, has a  =  0.304(1). This implies that classical percolative 2D superconductor-insulator transitions (SITs) generically have σ ≤ft(ω \\right)\\to ∞ as ω \\to 0 . Therefore, any experiments that give a constant conductivity as ω \\to 0 must be explained in terms of quantum effects.

  5. Poverty alleviation strategies in eastern China lead to critical ecological dynamics.

    Science.gov (United States)

    Zhang, Ke; Dearing, John A; Dawson, Terence P; Dong, Xuhui; Yang, Xiangdong; Zhang, Weiguo

    2015-02-15

    Poverty alleviation linked to agricultural intensification has been achieved in many regions but there is often only limited understanding of the impacts on ecological dynamics. A central need is to observe long term changes in regulating and supporting services as the basis for assessing the likelihood of sustainable agriculture or ecological collapse. We show how the analyses of 55 time-series of social, economic and ecological conditions can provide an evolutionary perspective for the modern Lower Yangtze River Basin region since the 1950s with powerful insights about the sustainability of modern ecosystem services. Increasing trends in provisioning ecosystem services within the region over the past 60 years reflect economic growth and successful poverty alleviation but are paralleled by steep losses in a range of regulating ecosystem services mainly since the 1980s. Increasing connectedness across the social and ecological domains after 1985 points to a greater uniformity in the drivers of the rural economy. Regime shifts and heightened levels of variability since the 1970s in local ecosystem services indicate progressive loss of resilience across the region. Of special concern are water quality services that have already passed critical transitions in several areas. Viewed collectively, our results suggest that the regional social-ecological system passed a tipping point in the late 1970s and is now in a transient phase heading towards a new steady state. However, the long-term relationship between economic growth and ecological degradation shows no sign of decoupling as demanded by the need to reverse an unsustainable trajectory.

  6. Multifluid, Magnetohydrodynamic Shock Waves with Grain Dynamics II. Dust and the Critical Speed for C Shocks

    CERN Document Server

    Ciolek, G E; Mouschovias, T C

    2004-01-01

    This is the second in a series of papers on the effects of dust on multifluid, MHD shock waves in weakly ionized molecular gas. We investigate the influence of dust on the critical shock speed, v_crit, above which C shocks cease to exist. Chernoff showed that v_crit cannot exceed the grain magnetosound speed, v_gms, if dust grains are dynamically well coupled to the magnetic field. We present numerical simulations of steady shocks where the grains may be well- or poorly coupled to the field. We use a time-dependent, multifluid MHD code that models the plasma as a system of interacting fluids: neutral particles, ions, electrons, and various ``dust fluids'' comprised of grains with different sizes and charges. Our simulations include grain inertia and grain charge fluctuations but to highlight the essential physics we assume adiabatic flow, single-size grains, and neglect the effects of chemistry. We show that the existence of a phase speed v_phi does not necessarily mean that C shocks will form for all shock s...

  7. Critical Dynamics of Gravito-Convective Mixing in Geological Carbon Sequestration

    Science.gov (United States)

    Soltanian, Mohamad Reza; Amooie, Mohammad Amin; Dai, Zhenxue; Cole, David; Moortgat, Joachim

    2016-11-01

    When CO2 is injected in saline aquifers, dissolution causes a local increase in brine density that can cause Rayleigh-Taylor-type gravitational instabilities. Depending on the Rayleigh number, density-driven flow may mix dissolved CO2 throughout the aquifer at fast advective time-scales through convective mixing. Heterogeneity can impact density-driven flow to different degrees. Zones with low effective vertical permeability may suppress fingering and reduce vertical spreading, while potentially increasing transverse mixing. In more complex heterogeneity, arising from the spatial organization of sedimentary facies, finger propagation is reduced in low permeability facies, but may be enhanced through more permeable facies. The connectivity of facies is critical in determining the large-scale transport of CO2-rich brine. We perform high-resolution finite element simulations of advection-diffusion transport of CO2 with a focus on facies-based bimodal heterogeneity. Permeability fields are generated by a Markov Chain approach, which represent facies architecture by commonly observed characteristics such as volume fractions. CO2 dissolution and phase behavior are modeled with the cubic-plus-association equation-of-state. Our results show that the organization of high-permeability facies and their connectivity control the dynamics of gravitationally unstable flow. We discover new flow regimes in both homogeneous and heterogeneous media and present quantitative scaling relations for their temporal evolution.

  8. Dynamic Critical Rainfall-Based Flash Flood Early Warning and Forecasting for Medium-Small Rivers

    Science.gov (United States)

    Liu, Z.; Yang, D.; Hu, J.

    2012-04-01

    China is extremely frequent food disasters hit countries, annual flood season flash floods triggered by rainfall, mudslides, landslides have caused heavy casualties and property losses, not only serious threaten the lives of the masses, but the majority of seriously restricting the mountain hill areas of economic and social development and the people become rich, of building a moderately prosperous society goals. In the next few years, China will focus on prevention and control area in the flash flood disasters initially built "for the surveillance, communications, forecasting, early warning and other non-engineering measure based, non-engineering measures and the combinations of engineering measures," the mitigation system. The latest progresses on global torrential flood early warning and forecasting techniques are reviewed in this paper, and then an early warning and forecasting approach is proposed on the basis of a distributed hydrological model according to dynamic critical rainfall index. This approach has been applied in Suichuanjiang River basin in Jiangxi province, which is expected to provide valuable reference for building a national flash flood early warning and forecasting system as well as control of such flooding.

  9. Study of spatio-temporal dynamics of laser-hole boring in near critical plasma

    Science.gov (United States)

    Tochitsky, Sergei; Gong, Chao; Fiuza, Frederico; Pigeon, Jeremy; Joshi, Chan

    2015-11-01

    At high-intensities of light, radiation pressure becomes one of the dominant mechanisms in laser-plasma interaction. The radiation pressure of an intense laser pulse can steepen and push the critical density region of an overdense plasma creating a cavity or a hole. This hole boring phenomenon is of importance in fast-ignition fusion, high-gradient laser-plasma ion acceleration, and formation of collisionless shocks. Here multi-frame picosecond optical interferometry is used for the first direct measurements of space and time dynamics of the density cavity as it is pushed forward by a train of CO2 laser pulses in a helium plasma. The measured values of the hole boring velocity into an overdense plasma as a function of laser intensity are consistent with a theory based on energy and momentum balance between the heated plasma and the laser and with two-dimensional numerical simulations. We show possibility to extract a relative plasma electron temperature within the laser pulse by applying an analytical theory to the measured hole boring velocities. This work was supported by DOE grant DE-SC0010064.

  10. SELF-ORGANIZED CRITICALITY AND CELLULAR AUTOMATA

    Energy Technology Data Exchange (ETDEWEB)

    CREUTZ,M.

    2007-01-01

    Cellular automata provide a fascinating class of dynamical systems based on very simple rules of evolution yet capable of displaying highly complex behavior. These include simplified models for many phenomena seen in nature. Among other things, they provide insight into self-organized criticality, wherein dissipative systems naturally drive themselves to a critical state with important phenomena occurring over a wide range of length and the scales. This article begins with an overview of self-organized criticality. This is followed by a discussion of a few examples of simple cellular automaton systems, some of which may exhibit critical behavior. Finally, some of the fascinating exact mathematical properties of the Bak-Tang-Wiesenfeld sand-pile model [1] are discussed.

  11. EZDCP:A new static task scheduling algorithm with edge-zeroing based on dynamic critical paths

    Institute of Scientific and Technical Information of China (English)

    陈志刚; 华强胜

    2003-01-01

    A new static task scheduling algorithm named edge-zeroing based on dynamic critical paths is proposed.The main ideas of the algorithm are as follows: firstly suppose that all of the tasks are in different clusters; secondly, select one of the critical paths of the partially clustered directed acyclic graph; thirdly, try to zero one of graph communication edges; fourthly, repeat above three processes until all edges are zeroed; finally, check the generated clusters to see if some of them can be further merged without increasing the parallel time. Comparisons of the previous algorithms with edge-zeroing based on dynamic critical paths show that the new algorithm has not only a low complexity but also a desired performance comparable or even better on average to much higher complexity heuristic algorithms.

  12. Dynamic wettability alteration in immiscible two-phase flow in porous media: Effect on transport properties and critical slowing down

    CERN Document Server

    Flovik, Vegard; Hansen, Alex

    2015-01-01

    The change in contact angles due to the injection of low salinity water or any other wettability altering agent in an oil-rich porous medium is modeled by a network model of disordered pores transporting two immiscible fluids. We introduce a dynamic wettability altering mechanism, where the time dependent wetting property of each pore is determined by the cumulative flow of water through it. Simulations are performed to reach steady-state for different possible alterations in the wetting angle ($\\theta$). We find that deviation from oil-wet conditions re-mobilizes the stuck clusters and increases the oil fractional flow. However, the rate of increase in the fractional flow depends strongly on $\\theta$ and as $\\theta\\to 90^\\circ$, a critical angle, the system shows critical slowing down which is characterized by two dynamic critical exponents.

  13. Dynamic wettability alteration in immiscible two-phase flow in porous media: Effect on transport properties and critical slowing down

    Directory of Open Access Journals (Sweden)

    Vegard eFlovik

    2015-11-01

    Full Text Available The change in contact angles due to the injection of low salinity water or any other wettability altering agent in an oil-rich porous medium is modeled by a network model of disordered pores transporting two immiscible fluids. We introduce a dynamic wettability altering mechanism, where the time dependent wetting property of each pore is determined by the cumulative flow of water through it. Simulations are performed to reach steady-state for different possible alterations in the wetting angle (θ. We find that deviation from oil-wet conditions re-mobilizes the stuck clusters and increases the oil fractional flow. However, the rate of increase in the fractional flow depends strongly on θ and as θ → 90◦ , a critical angle, the system shows critical slowing down which is characterized by two dynamic critical exponents.

  14. Evidence for Landau's critical velocity in superfluid helium nanodroplets from wave packet dynamics of attached potassium dimers

    CERN Document Server

    Schlesinger, Martin; Stienkemeier, Frank; Strunz, Walter T

    2009-01-01

    Femtosecond pump-probe spectroscopy has been used to study vibrational dynamics of potassium dimers attached to superfluid helium nanodroplets. Comparing the measured data with theoretical results based on dissipative quantum dynamics we propose that the most important effect of the helium environment is a general damping of the vibrational dynamics as a result of the interaction between dimer and collective degrees of freedom of the helium droplet. The calculations allow us to explain crucial experimental findings that are unobserved in gas-phase measurements. Remarkably, best agreement with experiment is found for a model where we neglect damping once a wave packet moves below a critical velocity. In this way the results provide first direct evidence for the Landau critical velocity in superfluid nanodroplets.

  15. Solid state phenomena

    CERN Document Server

    Lawrance, R

    1972-01-01

    Solid State Phenomena explores the fundamentals of the structure and their influence on the properties of solids. This book is composed of five chapters that focus on the electrical and thermal conductivities of crystalline solids. Chapter 1 describes the nature of solids, particularly metals and crystalline materials. This chapter also presents a model to evaluate crystal structure, the forces between atom pairs, and the mechanism of plastic and elastic deformation. Chapter 2 demonstrates random vibrations of atoms in a solid using a one-dimensional array, while Chapter 3 examines the resista

  16. Birefringence phenomena revisited

    CERN Document Server

    Pereira, Dante D; Gonçalves, Bruno

    2016-01-01

    The propagation of electromagnetic waves is investigated in the context of the isotropic and nonlinear dielectric media at rest in the eikonal limit of the geometrical optics. Taking into account the functional dependence $\\varepsilon=\\varepsilon(E,B)$ and $\\mu=\\mu(E,B)$ for the dielectric coefficients, a set of phenomena related to the birefringence of the electromagnetic waves induced by external fields are derived and discussed. Our results contemplate the known cases already reported in the literature: Kerr, Cotton-Mouton, Jones and magnetoelectric effects. Moreover, new effects are presented here as well as the perspectives of its experimental confirmations.

  17. Dissipative phenomena in condensed matter some applications

    CERN Document Server

    Dattagupta, Sushanta

    2004-01-01

    From the field of nonequilibrium statistical physics, this graduate- and research-level volume treats the modeling and characterization of dissipative phenomena. A variety of examples from diverse disciplines like condensed matter physics, materials science, metallurgy, chemical physics etc. are discussed. Dattagupta employs the broad framework of stochastic processes and master equation techniques to obtain models for a wide range of experimentally relevant phenomena such as classical and quantum Brownian motion, spin dynamics, kinetics of phase ordering, relaxation in glasses, dissipative tunneling. It provides a pedagogical exposition of current research material and will be useful to experimentalists, computational physicists and theorists.

  18. 19th International Conference on Ultrafast Phenomena

    CERN Document Server

    Cundiff, Steven; Vivie-Riedle, Regina; Kuwata-Gonokami, Makoto; DiMauro, Louis

    2015-01-01

    This book presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond, and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh-speed communications. This book summarizes the results presented at the 19th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.

  19. A dynamic modelling approach for estimating critical loads of nitrogen based on plant community changes under a changing climate

    Energy Technology Data Exchange (ETDEWEB)

    Belyazid, Salim, E-mail: salim@belyazid.com [Belyazid Consulting and Communication, Stationsvaegen 13, SE-517 34 Bollebygd (Sweden); Kurz, Dani [EKG Geoscience, Maulbeerstrasse 14, CH-3011 Bern (Switzerland); Braun, Sabine [Institut fuer Angewandte Planzenbiologie, Sandgrubenstrasse 25, CH-4124 Schoenenbuch (Switzerland); Sverdrup, Harald [Department of Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund (Sweden); Rihm, Beat [Meteotest, Fabrikstrasse 14, CH-3012 Bern (Switzerland); Hettelingh, Jean-Paul [Coordination Centre for Effects, PO Box 303, NL-3720 AH Bilthoven (Netherlands)

    2011-03-15

    A dynamic model of forest ecosystems was used to investigate the effects of climate change, atmospheric deposition and harvest intensity on 48 forest sites in Sweden (n = 16) and Switzerland (n = 32). The model was used to investigate the feasibility of deriving critical loads for nitrogen (N) deposition based on changes in plant community composition. The simulations show that climate and atmospheric deposition have comparably important effects on N mobilization in the soil, as climate triggers the release of organically bound nitrogen stored in the soil during the elevated deposition period. Climate has the most important effect on plant community composition, underlining the fact that this cannot be ignored in future simulations of vegetation dynamics. Harvest intensity has comparatively little effect on the plant community in the long term, while it may be detrimental in the short term following cutting. This study shows: that critical loads of N deposition can be estimated using the plant community as an indicator; that future climatic changes must be taken into account; and that the definition of the reference deposition is critical for the outcome of this estimate. - Research highlights: > Plant community changes can be used to estimate critical loads of nitrogen. > Climate change is decisive for future changes of geochemistry and plant communities. > Climate change cannot be ignored in estimates of critical loads. > The model ForSAFE-Veg was successfully used to set critical loads of nitrogen. - Plant community composition can be used in dynamic modelling to estimate critical loads of nitrogen deposition, provided the appropriate reference deposition, future climate and target plant communities are defined.

  20. On Equivalence between Critical Probabilities of Dynamic Gossip Protocol and Static Site Percolation

    Science.gov (United States)

    Ishikawa, Tetsuya; Hayakawa, Tomohisa

    The relationship between the critical probability of gossip protocol on the square lattice and the critical probability of site percolation on the square lattice is discussed. Specifically, these two critical probabilities are analytically shown to be equal to each other. Furthermore, we present a way of evaluating the critical probability of site percolation by approximating the saturation of gossip protocol. Finally, we provide numerical results which support the theoretical analysis.

  1. DMPD: Toll like receptors and autoimmunity: a critical appraisal. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17959357 Toll like receptors and autoimmunity: a critical appraisal. Papadimitraki ...ml) Show Toll like receptors and autoimmunity: a critical appraisal. PubmedID 17959357 Title Toll like recep...tors and autoimmunity: a critical appraisal. Authors Papadimitraki ED, Bertsias G

  2. Does the Sverdrup critical depth model explain bloom dynamics in estuaries?

    Science.gov (United States)

    Lucas, L.V.; Cloern, J.E.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

    1998-01-01

    In this paper we use numerical models of coupled biological-hydrodynamic processes to search for general principles of bloom regulation in estuarine waters. We address three questions: what are the dynamics of stratification in coastal systems as influenced by variable freshwater input and tidal stirring? How does phytoplankton growth respond to these dynamics? Can the classical Sverdrup Critical Depth Model (SCDM) be used to predict the timing of bloom events in shallow coastal domains such as estuaries? We present results of simulation experiments which assume that vertical transport and net phytoplankton growth rates are horizontally homogeneous. In the present approach the temporally and spatially varying turbulent diffusivities for various stratification scenarios are calculated using a hydrodynamic code that includes the Mellor-Yamada 2.5 turbulence closure model. These diffusivities are then used in a time- and depth-dependent advection-diffusion equation, incorporating sources and sinks, for the phytoplankton biomass. Our modeling results show that, whereas persistent stratification greatly increases the probability of a bloom, semidiurnal periodic stratification does not increase the likelihood of a phytoplankton bloom over that of a constantly unstratified water column. Thus, for phytoplankton blooms, the physical regime of periodic stratification is closer to complete mixing than to persistent stratification. Furthermore, the details of persistent stratification are important: surface layer depth, thickness of the pycnocline, vertical density difference, and tidal current speed all weigh heavily in producing conditions which promote the onset of phytoplankton blooms. Our model results for shallow tidal systems do not conform to the classical concepts of stratification and blooms in deep pelagic systems. First, earlier studies (Riley, 1942, for example) suggest a monotonic increase in surface layer production as the surface layer shallows. Our model

  3. A novel approach to locomotion learning: Actor-Critic architecture using central pattern generators and dynamic motor primitives.

    Science.gov (United States)

    Li, Cai; Lowe, Robert; Ziemke, Tom

    2014-01-01

    In this article, we propose an architecture of a bio-inspired controller that addresses the problem of learning different locomotion gaits for different robot morphologies. The modeling objective is split into two: baseline motion modeling and dynamics adaptation. Baseline motion modeling aims to achieve fundamental functions of a certain type of locomotion and dynamics adaptation provides a "reshaping" function for adapting the baseline motion to desired motion. Based on this assumption, a three-layer architecture is developed using central pattern generators (CPGs, a bio-inspired locomotor center for the baseline motion) and dynamic motor primitives (DMPs, a model with universal "reshaping" functions). In this article, we use this architecture with the actor-critic algorithms for finding a good "reshaping" function. In order to demonstrate the learning power of the actor-critic based architecture, we tested it on two experiments: (1) learning to crawl on a humanoid and, (2) learning to gallop on a puppy robot. Two types of actor-critic algorithms (policy search and policy gradient) are compared in order to evaluate the advantages and disadvantages of different actor-critic based learning algorithms for different morphologies. Finally, based on the analysis of the experimental results, a generic view/architecture for locomotion learning is discussed in the conclusion.

  4. A Novel Approach to Locomotion Learning: Actor-Critic Architecture using Central Pattern Generators and Dynamic Motor Primitives

    Directory of Open Access Journals (Sweden)

    Cai eLi

    2014-10-01

    Full Text Available In this article, we propose an architecture of a bio-inspired controller that addresses the problem of learning different locomotion gaits for different robot morphologies. The modelling objective is split into two: baseline motion modelling and dynamics adaptation. Baseline motion modelling aims to achieve fundamental functions of a certain type of locomotion and dynamics adaptation provides a ``reshaping function for adapting the baseline motion to desired motion. Based on this assumption, a three-layer architecture is developed using central pattern generators (CPGs, a bio-inspired locomotor center for the the baseline motion and dynamic motor primitives (DMPs, a model with universal ``reshaping functions. In this article, we use this architecture with the actor-critic algorithms for finding a good ``reshaping function. In order to demonstrate the learning power of the actor-critic based architecture, we tested it on two experiments: 1 learning to crawl on a humanoid and, 2 learning to gallop on a puppy robot. Two types of actor-critic algorithms (policy search and policy gradient are compared in order to evaluate the advantages and disadvantages of different actor-critic based learning algorithms for different morphologies. Finally, based on the analysis of the experimental results, a generic view/architecture for locomotion learning is discussed in the conclusion.

  5. Transport phenomena in strongly correlated Fermi liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kontani, Hiroshi [Nagoya Univ., Aichi (Japan). Dept. of Physics

    2013-03-01

    Comprehensive overview. Written by an expert of this topic. Provides the reader with current developments in the field. In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, {tau}, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical point using a uniform approach. We also discuss spin related transport phenomena in strongly correlated systems. In many d- and f-electron systems, the spin current induced by the spin Hall effect is considerably greater because of the orbital degrees of freedom. This fact attracts much attention due to its potential application in spintronics. We discuss various novel charge, spin and heat transport phenomena in strongly correlated metals.

  6. Control of quantum phenomena: Past, present, and future

    CERN Document Server

    Brif, Constantin; Rabitz, Herschel

    2009-01-01

    Quantum control is concerned with active manipulation of physical and chemical processes on the atomic and molecular scale. This work presents a perspective of progress in the field of control over quantum phenomena, tracing the evolution of theoretical concepts and experimental methods from early developments to the most recent advances. The current experimental successes would be impossible without the development of intense femtosecond laser sources and pulse shapers. The two most critical theoretical insights were (1) realizing that ultrafast atomic and molecular dynamics can be controlled via manipulation of quantum interferences and (2) understanding that optimally shaped ultrafast laser pulses are the most effective means for producing the desired quantum interference patterns in the controlled system. Finally, these theoretical and experimental advances were brought together by the crucial concept of adaptive feedback control, which is a laboratory procedure employing measurement-driven, closed-loop o...

  7. PREFACE Integrability and nonlinear phenomena Integrability and nonlinear phenomena

    Science.gov (United States)

    Gómez-Ullate, David; Lombardo, Sara; Mañas, Manuel; Mazzocco, Marta; Nijhoff, Frank; Sommacal, Matteo

    2010-10-01

    Back in 1967, Clifford Gardner, John Greene, Martin Kruskal and Robert Miura published a seminal paper in Physical Review Letters which was to become a cornerstone in the theory of integrable systems. In 2006, the authors of this paper received the AMS Steele Prize. In this award the AMS pointed out that `In applications of mathematics, solitons and their descendants (kinks, anti-kinks, instantons, and breathers) have entered and changed such diverse fields as nonlinear optics, plasma physics, and ocean, atmospheric, and planetary sciences. Nonlinearity has undergone a revolution: from a nuisance to be eliminated, to a new tool to be exploited.' From this discovery the modern theory of integrability bloomed, leading scientists to a deep understanding of many nonlinear phenomena which is by no means reachable by perturbation methods or other previous tools from linear theories. Nonlinear phenomena appear everywhere in nature, their description and understanding is therefore of great interest both from the theoretical and applicative point of view. If a nonlinear phenomenon can be represented by an integrable system then we have at our disposal a variety of tools to achieve a better mathematical description of the phenomenon. This special issue is largely dedicated to investigations of nonlinear phenomena which are related to the concept of integrability, either involving integrable systems themselves or because they use techniques from the theory of integrability. The idea of this special issue originated during the 18th edition of the Nonlinear Evolution Equations and Dynamical Systems (NEEDS) workshop, held at Isola Rossa, Sardinia, Italy, 16-23 May 2009 (http://needs-conferences.net/2009/). The issue benefits from the occasion offered by the meeting, in particular by its mini-workshops programme, and contains invited review papers and contributed papers. It is worth pointing out that there was an open call for papers and all contributions were peer reviewed

  8. Self-organized criticality and coevolution of network structure and dynamics.

    Science.gov (United States)

    Fronczak, Piotr; Fronczak, Agata; Hołyst, Janusz A

    2006-04-01

    We investigate, by numerical simulations, how the avalanche dynamics of the Bak-Tang-Wiesenfeld sandpile model can induce emergence of scale-free networks and how this emerging structure affects dynamics of the system.

  9. Workshop on Interface Phenomena

    CERN Document Server

    Kreuzer, Hans

    1987-01-01

    This book contains the proceedings of the first Workshop on Interface Phenomena, organized jointly by the surface science groups at Dalhousie University and the University of Maine. It was our intention to concentrate on just three topics related to the kinetics of interface reactions which, in our opinion, were frequently obscured unnecessarily in the literature and whose fundamental nature warranted an extensive discussion to help clarify the issues, very much in the spirit of the Discussions of the Faraday Society. Each session (day) saw two principal speakers expounding the different views; the session chairmen were asked to summarize the ensuing discussions. To understand the complexity of interface reactions, paradigms must be formulated to provide a framework for the interpretation of experimen­ tal data and for the construction of theoretical models. Phenomenological approaches have been based on a small number of rate equations for the concentrations or mole numbers of the various species involved i...

  10. Transport phenomena in strongly correlated Fermi liquids

    CERN Document Server

    Kontani, Hiroshi

    2013-01-01

    In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, \\tau, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical poi...

  11. Verification of new model for calculation of critical strain for the initialization of dynamic recrystallization using laboratory rolling

    Directory of Open Access Journals (Sweden)

    R. Fabík

    2009-10-01

    Full Text Available This paper presents a new model for calculation of critical strain for initialization of dynamic recrystallization. The new model reflects the history of forming in the deformation zone during rolling. In this region of restricted deformation, the strain rate curve for the surface of the strip exhibits two peaks. These are the two reasons why the onset of dynamic recrystallization DRX near the surface of the rolled part occurs later than in theory during strip rolling. The present model had been used in a program for simulation of forming processes with the aid of FEM and a comparison between the physical experiment and a mathematical model had been drawn.

  12. Falsification of Matching Theory and Confirmation of an Evolutionary Theory of Behavior Dynamics in a Critical Experiment.

    Science.gov (United States)

    McDowell, J J; Calvin, Olivia L; Hackett, Ryan; Klapes, Bryan

    2017-03-31

    Two competing predictions of matching theory and an evolutionary theory of behavior dynamics, and one additional prediction of the evolutionary theory, were tested in a critical experiment in which human participants worked on concurrent schedules for money (Dallery, Soto, and McDowell, 2005). The three predictions concerned the descriptive adequacy of matching theory equations, and of equations describing emergent equilibria of the evolutionary theory. Tests of the predictions falsified matching theory and supported the evolutionary theory.

  13. Complex-Dynamic Origin of Consciousness and the Critical Choice of Sustainability Transition

    OpenAIRE

    Kirilyuk, Andrei P.

    2004-01-01

    A quite general interaction process of a multi-component system is analysed by the extended effective potential method liberated from usual limitations of perturbation theory or integrable model. The obtained causally complete solution of the many-body problem reveals the phenomenon of dynamic multivaluedness, or redundance, of emerging, incompatible system realisations and dynamic entanglement of system components within each realisation. The ensuing concept of dynamic complexity (and relate...

  14. Coherent topological phenomena in protein folding

    DEFF Research Database (Denmark)

    Bohr, Henrik; Brunak, Søren; Bohr, Jakob

    1997-01-01

    A theory is presented for coherent topological phenomena in protein dynamics with implications for protein folding and stability. We discuss the relationship to the writhing number used in knot diagrams of DNA. The winding state defines a long-range order along the backbone of a protein with long......-range excitations, `wring' modes, that play an important role in protein denaturation and stability. Energy can be pumped into these excitations, either thermally or by an external force....

  15. Workshop on Nonlinear Phenomena in Complex Systems

    CERN Document Server

    1989-01-01

    This book contains a thorough treatment of neural networks, cellular-automata and synergetics, in an attempt to provide three different approaches to nonlinear phenomena in complex systems. These topics are of major interest to physicists active in the fields of statistical mechanics and dynamical systems. They have been developed with a high degree of sophistication and include the refinements necessary to work with the complexity of real systems as well as the more recent research developments in these areas.

  16. Properties of Neutron Star Critical Collapses

    Science.gov (United States)

    Wan, Mew-Bing

    2010-01-01

    Critical phenomena in gravitational collapse opened a new mathematical vista into the theory of general relativity and may ultimately entail fundamental physical implication in observations. However, at present, the dynamics of critical phenomena in gravitational collapse scenarios are still largely unknown. My thesis seeks to understand the properties of the threshold in the solution space of the Einstein field equations between the black hole and neutron star phases, understand the properties of the neutron star critical solution and clarify the implication of these results on realistic astrophysical scenarios. We develop a new set of neutron star-like initial data to establish the universality of the neutron star critical solution and analyze the structure of neutron star and neutron star-like critical collapses via the study of the phase spaces. We also study the different time scales involved in the neutron star critical solution and analyze the properties of the critical index via comparisons between neutron star and neutron star-like initial data. Finally, we explore the boundary of the attraction basin of the neutron star critical solution and its transition to a known set of non-critical fixed points.

  17. Criticality in Large-Scale Brain fMRI Dynamics Unveiled by a Novel Point Process Analysis

    Science.gov (United States)

    Tagliazucchi, Enzo; Balenzuela, Pablo; Fraiman, Daniel; Chialvo, Dante R.

    2012-01-01

    Functional magnetic resonance imaging (fMRI) techniques have contributed significantly to our understanding of brain function. Current methods are based on the analysis of gradual and continuous changes in the brain blood oxygenated level dependent (BOLD) signal. Departing from that approach, recent work has shown that equivalent results can be obtained by inspecting only the relatively large amplitude BOLD signal peaks, suggesting that relevant information can be condensed in discrete events. This idea is further explored here to demonstrate how brain dynamics at resting state can be captured just by the timing and location of such events, i.e., in terms of a spatiotemporal point process. The method allows, for the first time, to define a theoretical framework in terms of an order and control parameter derived from fMRI data, where the dynamical regime can be interpreted as one corresponding to a system close to the critical point of a second order phase transition. The analysis demonstrates that the resting brain spends most of the time near the critical point of such transition and exhibits avalanches of activity ruled by the same dynamical and statistical properties described previously for neuronal events at smaller scales. Given the demonstrated functional relevance of the resting state brain dynamics, its representation as a discrete process might facilitate large-scale analysis of brain function both in health and disease. PMID:22347863

  18. Linking Weathering, Rock Moisture Dynamics, Geochemistry, Runoff, Vegetation and Atmospheric Processes through the Critical Zone: Graduate Student led Research at the Eel River Critical Zone Observatory

    Science.gov (United States)

    Dietrich, W. E.

    2014-12-01

    In the Eel River Critical Zone Observatory lies Rivendell, a heavily-instrumented steep forested hillslope underlain by nearly vertically dipping argillite interbedded with sandstone. Under this convex hillslope lies "Zb", the transition to fresh bedrock, which varies from less than 6 m below the surface near the channel to 20 m at the divide. Rempe and Dietrich (2014, PNAS) show that the Zb profile can be predicted from the assumption that weathering occurs when drainage is induced in the uplifting fresh bedrock under hillslopes by lateral head gradients driven by channel incision at the hillslope boundary. Infiltrating winter precipitation is impeded at the lower conductivity boundary at Zb, generating perched groundwater that dynamically pulses water laterally to the channel, controlling stream runoff. Below the soil and above the water table lies an unsaturated zone through which all recharge to the perched groundwater (and thus all runoff to channels) occurs. It is this zone and the waters in them that profoundly affect critical zone processes. In our seasonally dry environment, the first rains penetrate past the soil and moisten the underlying weathered bedrock (Salve et al., 2012, WRR). It takes about 200 to 400 mm of cumulative rain, however, before the underlying groundwater rises significantly. Oshun et al (in review) show that by this cumulative rainfall the average of the wide-ranging isotopic signature of rain reaches a nearly constant average annual value. Consequently, the recharging perched groundwater shows only minor temporal isotopic variation. Kim et al, (2014, GCA) find that the winter high-flow groundwater chemistry is controlled by relatively fast-reacting cation exchange processes, likely occurring in transit in the unsaturated zone. Oshun also demonstrates that the Douglas fir rely on this rock moisture as a water source, while the broadleaf trees (oaks and madrone) use mostly soil moisture. Link et al (2014 WRR) show that Doug fir declines

  19. Bleed Hole Flow Phenomena Studied

    Science.gov (United States)

    1997-01-01

    Boundary-layer bleed is an invaluable tool for controlling the airflow in supersonic aircraft engine inlets. Incoming air is decelerated to subsonic speeds prior to entering the compressor via a series of oblique shocks. The low momentum flow in the boundary layer interacts with these shocks, growing in thickness and, under some conditions, leading to flow separation. To remedy this, bleed holes are strategically located to remove mass from the boundary layer, reducing its thickness and helping to maintain uniform flow to the compressor. The bleed requirements for any inlet design are unique and must be validated by extensive wind tunnel testing to optimize performance and efficiency. To accelerate this process and reduce cost, researchers at the NASA Lewis Research Center initiated an experimental program to study the flow phenomena associated with bleed holes. Knowledge of these flow properties will be incorporated into computational fluid dynamics (CFD) models that will aid engine inlet designers in optimizing bleed configurations before any hardware is fabricated. This ongoing investigation is currently examining two hole geometries, 90 and 20 (both with 5-mm diameters), and various flow features.

  20. Dynamics and collective phenomena of social systems

    OpenAIRE

    Gracia Lázaro, Carlos; Moreno Vega, Yamir; Floría Peralta, Luis Mario

    2012-01-01

    Esta tesis aborda el estudio de sistemas sociales utilizando los procedimientos teóricos de la física. Para abordar estos problemas existen evidentemente métodos de análisis y predictivos en la sociología, pero la aportación de la física proporciona tanto nuevas perspectivas complementarias como potentes herramientas. Este enfoque resulta especialmente útil en los problemas que involucran aspectos estocásticos y de dinámica no lineal. Los procedimientos utilizados pertenecen a la física de si...

  1. Power system dynamics: same phenomena; new challenges

    Energy Technology Data Exchange (ETDEWEB)

    Mansour, Yakout; Vaahedi, Ebraim; Xu, Wilsun; Chang, Allen [British Columbia Hydro, Vancouver, BC (Canada). Regional System Planning

    1994-12-31

    This paper presents a summary of how a utility met some challenges recently in two areas: transient angular stability and voltage stability. The paper also includes a view of what is evolving in these two areas. (author) 7 refs., 11 figs., 1 tab.

  2. Modeling mesoscopic phenomena in extended dynamical systems

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, A.; Lomdahl, P.; Jensen, N.G.; Cai, D.S. [Los Alamos National Lab., NM (United States); Mertenz, F. [Bayreuth Univ. (Germany); Konno, Hidetoshi [Tsukuba Univ., Ibaraki (Japan); Salkola, M. [Stanford Univ., CA (United States)

    1997-08-01

    This is the final report of a three-year, Laboratory-Directed Research and Development project at the Los Alamos National Laboratory (LANL). We have obtained classes of nonlinear solutions on curved geometries that demonstrate a novel interplay between topology and geometric frustration relevant for nanoscale systems. We have analyzed the nature and stability of localized oscillatory nonlinear excitations (multi-phonon bound states) on discrete nonlinear chains, including demonstrations of successful perturbation theories, existence of quasiperiodic excitations, response to external statistical time-dependent fields and point impurities, robustness in the presence of quantum fluctuations, and effects of boundary conditions. We have demonstrated multi-timescale effects for nonlinear Schroedinger descriptions and shown the success of memory function approaches for going beyond these approximations. In addition we have developed a generalized rate-equation framework that allows analysis of the important creation/annihilation processes in driven nonlinear, nonequilibiium systems.

  3. Soil phosphorus dynamic, balance and critical P values in long-term fertilization experiment in Taihu Lake region, China

    Institute of Scientific and Technical Information of China (English)

    SHI Lin-lin; SHEN Ming-xing; LU Chang-yin; WANG Hai-hou; ZHOU Xin-wei; JIN Mei-juan; WU Tong-dong

    2015-01-01

    Phosphorus (P) is an important macronutrient for plant but can also cause potential environmental risk. In this paper, we studied the long-term fertilizer experiment (started 1980) to assess the soil P dynamic, balance, critical P value and the crop yield response in Taihu Lake region, China. To avoid the effect of nitrogen (N) and potassium (K), only the folowing treatments were chosen for subsequent discussion, including: C0 (control treatment without any fertilizer or organic manure), CNK treatment (mineral N and K only), CNPK (balanced fertilization with mineral N, P and K), MNK (integrated organic ma-nure and mineral N and K), and MNPK (organic manure plus balanced fertilization). The results revealed that the response of wheat yield was more sensitive than rice, and no signiifcant differences of crop yield had been detected among MNK, CNPK and MNPK until 2013. Dynamic and balance of soil total P (TP) and Olsen-P showed soil TP pool was enlarged signiifcantly over consistent fertilization. However, the diminishing marginal utility of soil Olsen-P was also found, indicating that high-level P application in the present condition could not increase soil Olsen-P contents anymore. Linear-linear and Mitscherlich models were used to estimate the critical value of Olsen-P for crops. The average critical P value for rice and wheat was 3.40 and 4.08 mg kg–1, respectively. The smaler critical P value than in uplands indicated a stronger ability of P supply for crops in this paddy soil. We concluded that no more mineral P should be applied in rice-wheat system in Taihu Lake region if soil Olsen-P is higher than the critical P value. The agricultural technique and management referring to acti-vate the plant-available P pool are also considerable, such as integrated use of low-P organic manure with mineral N and K.

  4. Influence on the physical properties of methanol-hexane near the critical temperature of bundles

    OpenAIRE

    Породько, Лілія Володимирівна

    2012-01-01

    We are to consider the dynamics of critical phenomena in liquids and the effect of addition of ions on the phase transitions. The influence of the presence of ions on the behavior of inhomogeneous equilibrium solution methanol-hexane near the critical temperature stratification. Experimentally investigated the optical and thermodynamic equilibrium own pure methanol solutions-hexane and methanol-hexane, whether near the critical temperature stratification. Found equation coexistence dual...

  5. Critical Electron-Paramagnetic-Resonance Spin Dynamics in NiCl2

    DEFF Research Database (Denmark)

    Birgeneau, R.J.; Rupp, L.W.; Guggenheim, H.J.;

    1973-01-01

    We have studied the critical behavior of the electron-paramagnetic-resonance linewidth in the planar XY antiferromagnet NiCl2; it is found that the linewidth diverges like ξ∼(T-TN)-0.7 rather than ξ5/2 predicted by the current random-phase-approximation theory.......We have studied the critical behavior of the electron-paramagnetic-resonance linewidth in the planar XY antiferromagnet NiCl2; it is found that the linewidth diverges like ξ∼(T-TN)-0.7 rather than ξ5/2 predicted by the current random-phase-approximation theory....

  6. Transport Phenomena During Equiaxed Solidification of Alloys

    Science.gov (United States)

    Beckermann, C.; deGroh, H. C., III

    1997-01-01

    Recent progress in modeling of transport phenomena during dendritic alloy solidification is reviewed. Starting from the basic theorems of volume averaging, a general multiphase modeling framework is outlined. This framework allows for the incorporation of a variety of microscale phenomena in the macroscopic transport equations. For the case of diffusion dominated solidification, a simplified set of model equations is examined in detail and validated through comparisons with numerous experimental data for both columnar and equiaxed dendritic growth. This provides a critical assessment of the various model assumptions. Models that include melt flow and solid phase transport are also discussed, although their validation is still at an early stage. Several numerical results are presented that illustrate some of the profound effects of convective transport on the final compositional and structural characteristics of a solidified part. Important issues that deserve continuing attention are identified.

  7. Feedback control stabilization of critical dynamics via resource transport on multilayer networks: How glia enable learning dynamics in the brain

    Science.gov (United States)

    Virkar, Yogesh S.; Shew, Woodrow L.; Restrepo, Juan G.; Ott, Edward

    2016-10-01

    Learning and memory are acquired through long-lasting changes in synapses. In the simplest models, such synaptic potentiation typically leads to runaway excitation, but in reality there must exist processes that robustly preserve overall stability of the neural system dynamics. How is this accomplished? Various approaches to this basic question have been considered. Here we propose a particularly compelling and natural mechanism for preserving stability of learning neural systems. This mechanism is based on the global processes by which metabolic resources are distributed to the neurons by glial cells. Specifically, we introduce and study a model composed of two interacting networks: a model neural network interconnected by synapses that undergo spike-timing-dependent plasticity; and a model glial network interconnected by gap junctions that diffusively transport metabolic resources among the glia and, ultimately, to neural synapses where they are consumed. Our main result is that the biophysical constraints imposed by diffusive transport of metabolic resources through the glial network can prevent runaway growth of synaptic strength, both during ongoing activity and during learning. Our findings suggest a previously unappreciated role for glial transport of metabolites in the feedback control stabilization of neural network dynamics during learning.

  8. Dynamical aspects of Kinouchi-Copelli model: emergence of avalanches at criticality

    CERN Document Server

    Mosqueiro, T S; Maia, L P

    2011-01-01

    We analyze the behavior of bursts of neural activity in the Kinouchi-Copelli model, originally conceived to explain information processing issues in sensory systems. We show that, at a critical condition, power-law behavior emerges for the size and duration of the bursts (avalanches), with exponents experimentally observed in real biological systems.

  9. The Mock Trial: A Dynamic Exercise for Thinking Critically about Management Theories, Topics, and Practices

    Science.gov (United States)

    Farmer, Kevin; Meisel, Steven I.; Seltzer, Joe; Kane, Kathleen

    2013-01-01

    The Mock Trial is an experiential exercise adapted from a law school process that encourages students to think critically about theories, topics, and the practice of management in an innovative classroom experience. Playing the role of attorneys and witnesses, learners ask questions and challenge assumptions by playing roles in a trial with…

  10. Continuous thorium biosorption--dynamic study for critical bed depth determination in a fixed-bed reactor.

    Science.gov (United States)

    Picardo, Marta Cristina; Ferreira, Ana Cristina de Melo; da Costa, Antonio Carlos Augusto

    2009-01-01

    The objective of the work was to evaluate the biosorption of thorium by the seaweed Sargassum filipendula in a dynamic system. Different bed depths were tested with the purpose of evaluating the critical bed depth for total uptake of the radioactive element. Several bed depths were tested, ranging from 5.0 to 40.0 cm. Bed depths tested presented distinct capacities to accumulate thorium. An increase in biosorption efficiency was observed with an increase in bed depth. The 30.0 cm bed produced an effluent still containing detectable levels of thorium. The critical bed depth suitable for a complete removal of thorium by S.filipendula biomass was equal to 40.0 cm.

  11. Critical scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics

    1996-12-31

    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.

  12. Study of non-equilibrium transport phenomena

    Science.gov (United States)

    Sharma, Surendra P.

    1987-01-01

    Nonequilibrium phenomena due to real gas effects are very important features of low density hypersonic flows. The shock shape and emitted nonequilibrium radiation are identified as the bulk flow behavior parameters which are very sensitive to the nonequilibrium phenomena. These parameters can be measured in shock tubes, shock tunnels, and ballistic ranges and used to test the accuracy of computational fluid dynamic (CFD) codes. Since the CDF codes, by necessity, are based on multi-temperature models, it is also desirable to measure various temperatures, most importantly, the vibrational temperature. The CFD codes would require high temperature rate constants, which are not available at present. Experiments conducted at the NASA Electric Arc-driven Shock Tube (EAST) facility reveal that radiation from steel contaminants overwhelm the radiation from the test gas. For the measurement of radiation and the chemical parameters, further investigation and then appropriate modifications of the EAST facility are required.

  13. Critical Analysis of Underground Coal Gasification Models. Part II: Kinetic and Computational Fluid Dynamics Models

    Directory of Open Access Journals (Sweden)

    Alina Żogała

    2014-01-01

    Originality/value: This paper presents state of art in the field of coal gasification modeling using kinetic and computational fluid dynamics approach. The paper also presents own comparative analysis (concerned with mathematical formulation, input data and parameters, basic assumptions, obtained results etc. of the most important models of underground coal gasification.

  14. Advanced diffusion processes and phenomena

    CERN Document Server

    Öchsner, Andreas; Belova, Irina

    2014-01-01

    This topical volume on Advanced Diffusion Processes and Phenomena addresses diffusion in a wider sense of not only mass diffusion but also heat diffusion in fluids and solids. Both diffusion phenomena play an important role in the characterization of engineering materials and corresponding structures. Understanding these different transport phenomena at many levels, from atomistic to macro, has therefore long attracted the attention of many researchers in materials science and engineering and related disciplines. The present topical volume captures a representative cross-section of some of the

  15. Renormalization and Central limit theorem for critical dynamical systems with weak external noise

    CERN Document Server

    Diaz-Espinosa, O

    2006-01-01

    We study of the effect of weak noise on critical one dimensional maps; that is, maps with a renormalization theory. We establish a one dimensional central limit theorem for weak noises and obtain Berry--Esseen estimates for the rate of this convergence. We analyze in detail maps at the accumulation of period doubling and critical circle maps with golden mean rotation number. Using renormalization group methods, we derive scaling relations for several features of the effective noise after long times. We use these scaling relations to show that the central limit theorem for weak noise holds in both examples. We note that, for the results presented here, it is essential that the maps have parabolic behavior. They are false for hyperbolic orbits.

  16. Self-Organized Criticality and Stock Market Dynamics: an Empirical Study

    Energy Technology Data Exchange (ETDEWEB)

    M. Bartolozzi; D. B. Leinweber; A. W. Thomas

    2004-05-01

    The Stock Market is a complex self-interacting system, characterized by an intermittent behavior. Periods of high activity alternate with periods of relative calm. In the present work we investigate empirically about the possibility that the market is in a self-organized critical state (SOC). A wavelet transform method is used in order to separate high activity periods, related to the avalanches of sandpile models, from quiescent. A statistical analysis of the filtered data show a power law behavior in the avalanche size, duration and laminar times. The memory process, implied by the power law distribution, of the laminar times is not consistent with classical conservative models for self-organized criticality. We argue that a ''near-SOC'' state or a time dependence in the driver, which may be chaotic, can explain this behavior.

  17. Protecting Persistent Dynamic Oceanographic Features: Transboundary Conservation Efforts Are Needed for the Critically Endangered Balearic Shearwater

    OpenAIRE

    Maite Louzao; Karine Delord; David García; Amélie Boué; Henri Weimerskirch

    2012-01-01

    The protection of key areas for biodiversity at sea is not as widespread as on land and research investment is necessary to identify biodiversity hotspots in the open ocean. Spatially explicit conservation measures such as the creation of representative networks of marine protected areas (MPAs) is a critical step towards the conservation and management of marine ecosystems, as well as to improve public awareness. Conservation efforts in ecologically rich and threatened ecosystems are speciall...

  18. Lunar magma transport phenomena

    Science.gov (United States)

    Spera, Frank J.

    1992-01-01

    An outline of magma transport theory relevant to the evolution of a possible Lunar Magma Ocean and the origin and transport history of the later phase of mare basaltic volcanism is presented. A simple model is proposed to evaluate the extent of fractionation as magma traverses the cold lunar lithosphere. If Apollo green glasses are primitive and have not undergone significant fractionation en route to the surface, then mean ascent rates of 10 m/s and cracks of widths greater than 40 m are indicated. Lunar tephra and vesiculated basalts suggest that a volatile component plays a role in eruption dynamics. The predominant vapor species appear to be CO CO2, and COS. Near the lunar surface, the vapor fraction expands enormously and vapor internal energy is converted to mixture kinetic energy with the concomitant high-speed ejection of vapor and pyroclasts to form lunary fire fountain deposits such as the Apollo 17 orange and black glasses and Apollo 15 green glass.

  19. Dynamics Near the Ground State for the Energy Critical Nonlinear Heat Equation in Large Dimensions

    Science.gov (United States)

    Collot, Charles; Merle, Frank; Raphaël, Pierre

    2016-11-01

    We consider the energy critical semilinear heat equation partial_tu = Δ u + |u|^{4/d-2}u, quad x in R^d and give a complete classification of the flow near the ground state solitary wave Q(x) = 1/(1+{|x|^2/{d(d-2)})^{d-2/2}} in dimension {d ≥ 7} , in the energy critical topology and without radial symmetry assumption. Given an initial data {Q + ɛ_0} with {|nabla ɛ_0|_{L^2} ≪ 1} , the solution either blows up in the ODE type I regime, or dissipates, and these two open sets are separated by a codimension one set of solutions asymptotically attracted by the solitary wave. In particular, non self similar type II blow up is ruled out in dimension {d ≥ 7} near the solitary wave even though it is known to occur in smaller dimensions (Schweyer, J Funct Anal 263(12):3922-3983, 2012). Our proof is based on sole energy estimates deeply connected to Martel et al. (Acta Math 212(1):59-140, 2014) and draws a route map for the classification of the flow near the solitary wave in the energy critical setting. A by-product of our method is the classification of minimal elements around Q belonging to the unstable manifold.

  20. Critical current and flux dynamics in Ag-doped FeSe superconductor

    Science.gov (United States)

    Galluzzi, A.; Polichetti, M.; Buchkov, K.; Nazarova, E.; Mancusi, D.; Pace, S.

    2017-02-01

    The measurements of DC magnetization as a function of the temperature M(T), magnetic field M(H), and time M(t) have been performed in order to compare the superconducting and pinning properties of an undoped FeSe0.94 sample and a silver doped FeSe0.94 + 6 wt% Ag sample. The M(T) curves indicate an improvement of the superconducting critical temperature and a reduction of the non-superconducting phase Fe7Se8 due to the silver doping. This is confirmed by the field and temperature dependent critical current density Jc(H,T) extracted from the superconducting hysteresis loops at different temperatures within the Bean critical state model. Moreover, the combined analysis of the Jc(T) and of the pinning force Fp(H/Hirr) indicate that the pinning mechanisms in both samples can be described in the framework of the collective pinning theory. The U*(T, J) curves show a pinning crossover from an elastic creep regime of intermediate size flux bundles, for low temperatures, to a plastic creep regime at higher temperatures for both the samples. Finally, the vortex hopping attempt time has been evaluated for both samples and the results are comparable with the values reported in the literature for high Tc materials.

  1. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films.

    Science.gov (United States)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  2. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S [CNR-INFM Laboratorio Regionale SuperMat, Via Salvador Allende, I-84081 Baronissi (Italy)], E-mail: grimaldi@sa.infn.it

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  3. Autoregressive description of biological phenomena

    CERN Document Server

    Morariu, Vasile V; Pop, Alexadru; Soltuz, Stefan M; Buimaga-Iarinca, Luiza; Zainea, Oana

    2008-01-01

    Many natural phenomena can be described by power-laws. A closer look at various experimental data reveals more or less significant deviations from a 1/f spectrum. We exemplify such cases with phenomena offered by molecular biology, cell biophysics, and cognitive psychology. Some of these cases can be described by first order autoregressive (AR) models or by higher order AR models which are short range correlation models. The calculations are checked against astrophysical data which were fitted to a an AR model by a different method. We found that our fitting method of the data give similar results for the astrhophysical data and therefore applied the method for examples mentioned above. Our results show that such phenomena can be described by first or higher order of AR models. Therefore such examples are described by short range correlation properties while they can be easily confounded with long range correlation phenomena.

  4. Renormalization of weak noises of arbitrary shape for one-dimensional critical dynamical systems Announcement of results and numerical explorations

    CERN Document Server

    Diaz-Espinosa, O

    2006-01-01

    We study the effect of noise on one--dimensional critical dynamical systems (that is, maps with a renormalization theory). We consider in detail two examples of such dynamical systems: unimodal maps of the interval at the accumulation of period--doubling and smooth homeomorphisms of the circle with a critical point and with golden mean rotation number. We show that, if we scale the space and the time, several properties of the noise (the cumulants or Wick--ordered moments) satisfy some scaling relations. A consequence of the scaling relations is that a version of the central limit theorem holds. Irrespective of the shape of the initial noise, if the bare noise is weak enough, the effective noise becomes close to Gaussian in several senses that we can make precise. We notice that the conclusions are false for maps with positive Lyapunov exponents. The method of analysis is close in spirit to the study of scaling limits in renormalization theory. We also perform several numerical experiments that confirm the ri...

  5. Dynamical criticality during induction of anesthesia in human ECoG recordings

    Directory of Open Access Journals (Sweden)

    Leandro M. Alonso

    2014-03-01

    Full Text Available In this work we analyze electro-corticography (ECoG recordings in human sub- jects as they are anesthetized. We hypothesize that the decrease in responsiveness that defines anesthesia induction is concomitant with the stabilization of neuronal dynamics. To test this hypothesis, we performed a moving vector autoregressive analysis and quantified stability of neuronal dynamics using eigenmode decompo- sition of the autoregressive matrices, independently fitted to short sliding temporal windows. Consistent with the hypothesis we show that while the subject is awake, many modes of oscillations of neuronal activity are found at the edge of instabil- ity, but as the subject becomes anesthetized the fitted dynamics becomes more damped. Analysis of eigenmode distributions in the awake and anesthetized brain revealed statistically significant stabilization not present in surrogate data. Sta- bility analysis thus offer a novel way of quantifying changes in neuronal activity that characterize loss of consciousness induced by general anesthetics. Specifically, our analysis suggests that the effect of the anesthetic procedure is to damp out high frequency activity while still allowing for low frequency modes to perform a function.

  6. Transient chaos and crisis phenomena in butterfly valves driven by solenoid actuators

    Science.gov (United States)

    Naseradinmousavi, Peiman; Nataraj, C.

    2012-11-01

    Chilled water systems used in the industry and on board ships are critical for safe and reliable operation. It is hence important to understand the fundamental physics of these systems. This paper focuses in particular on a critical part of the automation system, namely, actuators and valves that are used in so-called "smart valve" systems. The system is strongly nonlinear, and necessitates a nonlinear dynamic analysis to be able to predict all critical phenomena that affect effective operation and efficient design. The derived mathematical model includes electromagnetics, fluid mechanics, and mechanical dynamics. Nondimensionalization has been carried out in order to reduce the large number of parameters to a few critical independent sets to help carry out a broad parametric analysis. The system stability analysis is then carried out with the aid of the tools from nonlinear dynamic analysis. This reveals that the system is unstable in a certain region of the parameter space. The system is also shown to exhibit crisis and transient chaotic responses; this is characterized using Lyapunov exponents and power spectra. Knowledge and avoidance of these dangerous regimes is necessary for successful and safe operation.

  7. Self-organized criticality and the dynamics of near-marginal turbulent transport in magnetically confined fusion plasmas

    Science.gov (United States)

    Sanchez, R.; Newman, D. E.

    2015-12-01

    The high plasma temperatures expected at reactor conditions in magnetic confinement fusion toroidal devices suggest that near-marginal operation could be a reality in future devices and reactors. By near-marginal it is meant that the plasma profiles might wander around the local critical thresholds for the onset of instabilities. Self-organized criticality (SOC) was suggested in the mid 1990s as a more proper paradigm to describe the dynamics of tokamak plasma transport in near-marginal conditions. It advocated that, near marginality, the evolution of mean profiles and fluctuations should be considered simultaneously, in contrast to the more common view of a large separation of scales existing between them. Otherwise, intrinsic features of near-marginal transport would be missed, that are of importance to understand the properties of energy confinement. In the intervening 20 years, the relevance of the idea of SOC for near-marginal transport in fusion plasmas has transitioned from an initial excessive hype to the much more realistic standing of today, which we will attempt to examine critically in this review paper. First, the main theoretical ideas behind SOC will be described. Secondly, how they might relate to the dynamics of near-marginal transport in real magnetically confined plasmas will be discussed. Next, we will review what has been learnt about SOC from various numerical studies and what it has meant for the way in which we do numerical simulation of fusion plasmas today. Then, we will discuss the experimental evidence available from the several experiments that have looked for SOC dynamics in fusion plasmas. Finally, we will conclude by identifying the various problems that still remain open to investigation in this area. Special attention will be given to the discussion of frequent misconceptions and ongoing controversies. The review also contains a description of ongoing efforts that seek effective transport models better suited than traditional

  8. Time-Variable Phenomena in the Jovian System

    Science.gov (United States)

    Belton, Michael J. S. (Editor); West, Robert A. (Editor); Rahe, Jurgen (Editor); Pereyda, Margarita

    1989-01-01

    The current state of knowledge of dynamic processes in the Jovian system is assessed and summaries are provided of both theoretical and observational foundations upon which future research might be based. There are three sections: satellite phenomena and rings; magnetospheric phenomena, Io's torus, and aurorae; and atmospheric phenomena. Each chapter discusses time dependent theoretical framework for understanding and interpreting what is observed; others describe the evidence and nature of observed changes or their absence. A few chapters provide historical perspective and attempt to present a comprehensive synthesis of the current state of knowledge.

  9. New Nonequilibrium-to-Equilibrium Dynamical Scaling and Stretched-Exponential Critical Relaxation in Cluster Algorithms

    Science.gov (United States)

    Nonomura, Yoshihiko

    2014-11-01

    Nonequilibrium relaxation behaviors in the Ising model on a square lattice based on the Wolff algorithm are totally different from those based on local-update algorithms. In particular, the critical relaxation is described by the stretched-exponential decay. We propose a novel scaling procedure to connect nonequilibrium and equilibrium behaviors continuously, and find that the stretched-exponential scaling region in the Wolff algorithm is as wide as the power-law scaling region in local-update algorithms. We also find that relaxation to the spontaneous magnetization in the ordered phase is characterized by the exponential decay, not the stretched-exponential decay based on local-update algorithms.

  10. Dynamic Critical Behaviour of Wolff's Algorithm for $RP^N$ $\\sigma$-Models

    OpenAIRE

    Caracciolo, S.; Edwards, R. G.; Pelissetto, A.; Sokal, A. D.

    1992-01-01

    We study the performance of a Wolff-type embedding algorithm for $RP^N$ $\\sigma$-models. We find that the algorithm in which we update the embedded Ising model \\`a la Swendsen-Wang has critical slowing-down as $z_\\chi \\approx 1$. If instead we update the Ising spins with a perfect algorithm which at every iteration produces a new independent configuration, we obtain $z_\\chi \\approx 0$. This shows that the Ising embedding encodes well the collective modes of the system, and that the behaviour ...

  11. Poverty alleviation strategies in eastern China lead to critical ecological dynamics

    DEFF Research Database (Denmark)

    2015-01-01

    are water quality services that have already passed critical transitions in several areas. Viewed collectively, our results suggest that the regional social– ecological systempassed a tipping point in the late 1970s and is nowin a transient phase heading towards a new steady state. However, the long...... connectedness across the social and ecological domains after 1985 points to a greater uniformity in the drivers of the rural economy. Regime shifts and heightened levels of variability since the 1970s in local ecosystem services indicate progressive loss of resilience across the region. Of special concern...

  12. Quantum-to-classical crossover near quantum critical point.

    Science.gov (United States)

    Vasin, M; Ryzhov, V; Vinokur, V M

    2015-12-21

    A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d + zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T) ∈ [0, 1] decreases with the temperature such that Λ(T = 0) = 1 and Λ(T → ∞) = 0. Our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.

  13. Comparison between the Methods of Determining the Critical Stress for Initiation of Dynamic Recrystallization in 316 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    M.Jafari; A.Najafizadeh

    2008-01-01

    Several methods have been proposed to calculate the critical stress for initiation of dynamic recrystallization (σc) on the basis of mathematical methods.One of them is proposed by Stewart et al.in which this critical point appears as a distinct minimum in the (-dθ/dσ vs σ) through differentiating from θ vs σ.Another one is presented by Najafizadeh and Jonas by modifying the Poliak and Jonas method.According to this method,the strain hardening rate was plotted against flow stress,and the value of σc was attained numerically from the coefficients of the third-order equation that was the best fit from the experimental θ-σ data.Hot compression tests were used in the range of 1000 to 1100℃ with strain rates of 0.01-1 s-1 and strain of 1 on 316 stainless steel.The result shows that Najafizadeh and Jonas method is simpler than the previous one,and has a good agreement with microstructures.Furthermore,the value of normalized critical stress for this steel was obtained uc=σc/σp=0.92.

  14. Computational fluid dynamics model of WTP clearwell: Evaluation of critical parameters influencing model performance

    Energy Technology Data Exchange (ETDEWEB)

    Ducoste, J.; Brauer, R.

    1999-07-01

    Analysis of a computational fluid dynamics (CFD) model for a water treatment plant clearwell was done. Model parameters were analyzed to determine their influence on the effluent-residence time distribution (RTD) function. The study revealed that several model parameters could have significant impact on the shape of the RTD function and consequently raise the level of uncertainty on accurate predictions of clearwell hydraulics. The study also revealed that although the modeler could select a distribution of values for some of the model parameters, most of these values can be ruled out by requiring the difference between the calculated and theoretical hydraulic retention time to within 5% of the theoretical value.

  15. Dynamics of an Interacting Particle System: Evidence of Critical Slowing Down

    DEFF Research Database (Denmark)

    Djurberg, Claes; Svedlindh, Peter; Nordblad, Per;

    1997-01-01

    The dynamics of a magnetic particle system consisting of ultrafine Fe-C particles of monodisperse nature has been investigated in a large time window, 10(-9)-10(4) s, using Mossbauer spectroscopy, ac susceptibility, and zero field cooled magnetic relaxation measurements. By studying two samples...... from the same dilution series, with concentrations of 5 and 6 x 10(-3) vol%, respectively, it has been found that dipole-dipole interaction increases the characteristic relaxation time of the particle system at all temperatures investigated. The results for the most concentrated particle assembly...

  16. Quenching phenomena in natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Umekawa, Hisashi; Ozawa, Mamoru [Kansai Univ., Osaka (Japan); Ishida, Naoki [Daihatsu Motor Company, Osaka (Japan)

    1995-09-01

    Quenching phenomena has been investigated experimentally using circulation loop of liquid nitrogen. During the quenching under natural circulation, the heat transfer mode changes from film boiling to nucleate boiling, and at the same time flux changes with time depending on the vapor generation rate and related two-phase flow characteristics. Moreover, density wave oscillations occur under a certain operating condition, which is closely related to the dynamic behavior of the cooling curve. The experimental results indicates that the occurrence of the density wave oscillation induces the deterioration of effective cooling of the heat surface in the film and the transition boiling regions, which results in the decrease in the quenching velocity.

  17. Layered phenomena in the mesopause region

    Science.gov (United States)

    Plane, J. M. C.; Bailey, S. M.; Baumgarten, G.; Rapp, M.

    2015-05-01

    This special issue of the Journal of Atmospheric and Solar-Terrestrial Physics comprises a collection of papers which were mostly presented at the 11th Layered Phenomena in the Mesopause Region (LPMR) Workshop, held at the University of Leeds between 29th July 2013 and 1st August 2013. The topics covered at the workshop included atmospheric dynamics, mesospheric ice clouds, meteoric metal layers, meteoric smoke particles, and airglow layers. There was also a session on the potential of planned sub-orbital spacecraft for making measurements in the mesosphere and lower thermosphere (MLT).

  18. Thermal transport phenomena in nanoparticle suspensions

    Science.gov (United States)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-12-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications.

  19. Critical behaviour of reduced QED$_{4,3}$ and dynamical fermion gap generation in graphene

    CERN Document Server

    Kotikov, A V

    2016-01-01

    The dynamical generation of a fermion gap in graphene is studied at the infra-red Lorentz-invariant fixed point where the system is described by an effective relativistic-like field theory: reduced QED$_{4,3}$ with $N$ four component fermions ($N=2$ for graphene), where photons are $(3+1)$-dimensional and mediate a fully retarded interaction among $(2+1)$-dimensional fermions. A correspondence between reduced QED$_{4,3}$ and QED$_3$ allows us to derive an exact gap equation for QED$_{4,3}$ up to next-to-leading order. Our results show that a dynamical gap is generated for $\\alpha > \\alpha_c$ where $1.03 < \\alpha_c < 1.08$ in the case $N=2$ or for $N < N_c$ where $N_c$ is such that $\\alpha_c \\to \\infty$ and takes the values $3.24 < N_c < 3.36$. The striking feature of these results is that they are in good agreement with values found in models with instantaneous Coulomb interaction. At the fixed point: $\\alpha = 1/137 \\ll \\alpha_c$, and the system is therefore in the semi-metallic regime in acco...

  20. Critical behavior of reduced QED4 ,3 and dynamical fermion gap generation in graphene

    Science.gov (United States)

    Kotikov, A. V.; Teber, S.

    2016-12-01

    The dynamical generation of a fermion gap in graphene is studied at the infra-red Lorentz-invariant fixed point where the system is described by an effective relativistic-like field theory: reduced QED4 ,3 with N four-component fermions (N =2 for graphene), where photons are (3 +1 ) dimensional and mediate a fully retarded interaction among (2 +1 )-dimensional fermions. A correspondence between reduced QED4 ,3 and QED3 allows us to derive an exact gap equation for QED4 ,3 up to next-to-leading order. Our results show that a dynamical gap is generated for α >αc, where 1.03 <αc<1.08 in the case N =2 or for N

  1. Early sepsis detection in critical care patients using multiscale blood pressure and heart rate dynamics.

    Science.gov (United States)

    Shashikumar, Supreeth P; Stanley, Matthew D; Sadiq, Ismail; Li, Qiao; Holder, Andre; Clifford, Gari D; Nemati, Shamim

    2017-08-16

    Sepsis remains a leading cause of morbidity and mortality among intensive care unit (ICU) patients. For each hour treatment initiation is delayed after diagnosis, sepsis-related mortality increases by approximately 8%. Therefore, maximizing effective care requires early recognition and initiation of treatment protocols. Antecedent signs and symptoms of sepsis can be subtle and unrecognizable (e.g., loss of autonomic regulation of vital signs), causing treatment delays and harm to the patient. In this work we investigated the utility of high-resolution blood pressure (BP) and heart rate (HR) times series dynamics for the early prediction of sepsis in patients from an urban, academic hospital, meeting the third international consensus definition of sepsis (sepsis-III) during their ICU admission. Using a multivariate modeling approach we found that HR and BP dynamics at multiple time-scales are independent predictors of sepsis, even after adjusting for commonly measured clinical values and patient demographics and comorbidities. Earlier recognition and diagnosis of sepsis has the potential to decrease sepsis-related morbidity and mortality through earlier initiation of treatment protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Plasma dynamics near critical density inferred from direct measurements of laser hole boring.

    Science.gov (United States)

    Gong, Chao; Tochitsky, Sergei Ya; Fiuza, Frederico; Pigeon, Jeremy J; Joshi, Chan

    2016-06-01

    We have used multiframe picosecond optical interferometry to make direct measurements of the hole boring velocity, v_{HB}, of the density cavity pushed forward by a train of CO_{2} laser pulses in a near critical density helium plasma. As the pulse train intensity rises, the increasing radiation pressure of each pulse pushes the density cavity forward and the plasma electrons are strongly heated. After the peak laser intensity, the plasma pressure exerted by the heated electrons strongly impedes the hole boring process and the v_{HB} falls rapidly as the laser pulse intensity falls at the back of the laser pulse train. A heuristic theory is presented that allows the estimation of the plasma electron temperature from the measurements of the hole boring velocity. The measured values of v_{HB}, and the estimated values of the heated electron temperature as a function of laser intensity are in reasonable agreement with those obtained from two-dimensional numerical simulations.

  3. Critical dynamical properties of a first-order dissipative phase transition

    Science.gov (United States)

    Casteels, W.; Fazio, R.; Ciuti, C.

    2017-01-01

    We theoretically investigate the critical properties of a single driven-dissipative nonlinear photon mode. In a well-defined thermodynamical limit of large excitation numbers, the exact quantum solution describes a first-order phase transition in the regime where semiclassical theory predicts optical bistability. We study the behavior of the complex spectral gap associated with the Liouvillian superoperator of the corresponding master equation. We show that in this limit the Liouvillian gap vanishes exponentially and that the bimodality of the photon Wigner function disappears. The connection between the considered thermodynamical limit of large photon numbers for the single-mode cavity and the thermodynamical limit of many cavities for a driven-dissipative Bose-Hubbard system is discussed.

  4. Dynamic Critical Behaviour of Wolff's Algorithm for $RP^N$ $\\sigma$-Models

    CERN Document Server

    Caracciolo, Sergio; Pelissetto, A; Sokal, A D

    1992-01-01

    We study the performance of a Wolff-type embedding algorithm for $RP^N$ $\\sigma$-models. We find that the algorithm in which we update the embedded Ising model \\`a la Swendsen-Wang has critical slowing-down as $z_\\chi \\approx 1$. If instead we update the Ising spins with a perfect algorithm which at every iteration produces a new independent configuration, we obtain $z_\\chi \\approx 0$. This shows that the Ising embedding encodes well the collective modes of the system, and that the behaviour of the first algorithm is connected to the poor performance of the Swendsen-Wang algorithm in dealing with a frustrated Ising model.

  5. Protecting persistent dynamic oceanographic features: transboundary conservation efforts are needed for the critically endangered Balearic shearwater.

    Science.gov (United States)

    Louzao, Maite; Delord, Karine; García, David; Boué, Amélie; Weimerskirch, Henri

    2012-01-01

    The protection of key areas for biodiversity at sea is not as widespread as on land and research investment is necessary to identify biodiversity hotspots in the open ocean. Spatially explicit conservation measures such as the creation of representative networks of marine protected areas (MPAs) is a critical step towards the conservation and management of marine ecosystems, as well as to improve public awareness. Conservation efforts in ecologically rich and threatened ecosystems are specially needed. This is particularly urgent for the Mediterranean marine biodiversity, which includes highly mobile marine vertebrates. Here, we studied the at sea distribution of one of the most endangered Mediterranean seabird, the critically endangered Balearic shearwater Puffinus mauretanicus. Present knowledge, from vessel-based surveys, suggests that this species has a coastal distribution over the productive Iberian shelf in relation to the distribution of their main prey, small pelagic fish. We used miniaturised satellite transmitters to determine the key marine areas of the southern population of Balearic shearwaters breeding on Eivissa and spot the spatial connections between breeding and key marine areas. Our tracking study indicates that Balearic shearwaters do not only forage along the Iberian continental shelf but also in more distant marine areas along the North African coast, in particular W of Algeria, but also NE coast of Morocco. Birds recurrently visit these shelf areas at the end of the breeding season. Species distribution modelling identified chlorophyll a as the most important environmental variable in defining those oceanographic features characterizing their key habitats in the western Mediterranean. We identified persistent oceanographic features across time series available in the study area and discuss our results within the current conservation scenario in relation to the ecology of the species.

  6. Protecting persistent dynamic oceanographic features: transboundary conservation efforts are needed for the critically endangered Balearic shearwater.

    Directory of Open Access Journals (Sweden)

    Maite Louzao

    Full Text Available The protection of key areas for biodiversity at sea is not as widespread as on land and research investment is necessary to identify biodiversity hotspots in the open ocean. Spatially explicit conservation measures such as the creation of representative networks of marine protected areas (MPAs is a critical step towards the conservation and management of marine ecosystems, as well as to improve public awareness. Conservation efforts in ecologically rich and threatened ecosystems are specially needed. This is particularly urgent for the Mediterranean marine biodiversity, which includes highly mobile marine vertebrates. Here, we studied the at sea distribution of one of the most endangered Mediterranean seabird, the critically endangered Balearic shearwater Puffinus mauretanicus. Present knowledge, from vessel-based surveys, suggests that this species has a coastal distribution over the productive Iberian shelf in relation to the distribution of their main prey, small pelagic fish. We used miniaturised satellite transmitters to determine the key marine areas of the southern population of Balearic shearwaters breeding on Eivissa and spot the spatial connections between breeding and key marine areas. Our tracking study indicates that Balearic shearwaters do not only forage along the Iberian continental shelf but also in more distant marine areas along the North African coast, in particular W of Algeria, but also NE coast of Morocco. Birds recurrently visit these shelf areas at the end of the breeding season. Species distribution modelling identified chlorophyll a as the most important environmental variable in defining those oceanographic features characterizing their key habitats in the western Mediterranean. We identified persistent oceanographic features across time series available in the study area and discuss our results within the current conservation scenario in relation to the ecology of the species.

  7. National implementation of the UNECE convention on long-range transboundary air pollution (effects). Pt. 2. Impacts and risk estimation, critical loads, biodiversity, dynamic modelling, critical level violation, material corrosion; Nationale Umsetzung UNECE-Luftreinhaltekonvention (Wirkungen). T. 2. Wirkungen und Risikoabschaetzungen Critical Loads, Biodiversitaet, Dynamische Modellierung, Critical Levels Ueberschreitungen, Materialkorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Gauger, Thomas [Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (DE). Inst. fuer Agraroekologie (FAL-AOE); Stuttgart Univ. (Germany). Inst. fuer Navigation; Haenel, Hans-Dieter; Roesemann, Claus [Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (DE). Inst. fuer Agraroekologie (FAL-AOE); Nagel, Hans-Dieter; Becker, Rolf; Kraft, Philipp; Schlutow, Angela; Schuetze, Gudrun; Weigelt-Kirchner, Regine [OeKO-DATA Gesellschaft fuer Oekosystemanalyse und Umweltdatenmanagement mbH, Strausberg (Germany); Anshelm, Frank [Geotechnik Suedwest Frey Marx GbR, Bietigheim-Bissingen (Germany)

    2008-09-15

    The report on the implementation of the UNECE convention on long-range transboundary air pollution Pt.2 covers the following issues: The tasks of the NFC (National Focal Center) Germany including the ICP (international cooperative program) modeling and mapping and the expert panel for heavy metals. Results of the work for the multi-component protocol cover the initial data for the calculation of the critical loads following the mass balance method, critical loads for acid deposition, critical loads for nitrogen input, critical load violations (sulfur, nitrogen). The results of work for the heavy metal protocol cover methodology development and recommendations for ICO modeling and mapping in accordance with international development, contributions of the expert group/ task force on heavy metals (WGSR), data sets on the critical loads for lead, cadmium and mercury, and critical load violations (Pb, Cd, Hg). The results of work on the inclusion of biodiversity (BERN) cover data compilation, acquisition and integration concerning ecosystems, model validation and verification and the possible interpretation frame following the coupling with dynamic modeling. The future development and utilization of dynamic modeling covers model comparison, applicability, the preparation of a national data set and preparations concerning the interface to the BERN model.

  8. Critical Bottleneck Size for Jamless Particle Flows in Two Dimensions

    Science.gov (United States)

    Masuda, Takumi; Nishinari, Katsuhiro; Schadschneider, Andreas

    2014-04-01

    We propose a simple microscopic model for arching phenomena at bottlenecks. The dynamics of particles in front of a bottleneck is described by a one-dimensional stochastic cellular automaton on a semicircular geometry. The model reproduces oscillation phenomena due to the formation and collapsing of arches. It predicts the existence of a critical bottleneck size for continuous particle flows. The dependence of the jamming probability on the system size is approximated by the Gompertz function. The analytical results are in good agreement with simulations.

  9. Investigating Human Neurovascular Coupling Using Functional Neuroimaging: A Critical Review of Dynamic Models.

    Science.gov (United States)

    Huneau, Clément; Benali, Habib; Chabriat, Hugues

    2015-01-01

    The mechanisms that link a transient neural activity to the corresponding increase of cerebral blood flow (CBF) are termed neurovascular coupling (NVC). They are possibly impaired at early stages of small vessel or neurodegenerative diseases. Investigation of NVC in humans has been made possible with the development of various neuroimaging techniques based on variations of local hemodynamics during neural activity. Specific dynamic models are currently used for interpreting these data that can include biophysical parameters related to NVC. After a brief review of the current knowledge about possible mechanisms acting in NVC we selected seven models with explicit integration of NVC found in the literature. All these models were described using the same procedure. We compared their physiological assumptions, mathematical formalism, and validation. In particular, we pointed out their strong differences in terms of complexity. Finally, we discussed their validity and their potential applications. These models may provide key information to investigate various aspects of NVC in human pathology.

  10. Investigating human neurovascular coupling using functional neuroimaging: a critical review of dynamic models

    Directory of Open Access Journals (Sweden)

    Clément eHuneau

    2015-12-01

    Full Text Available The mechanisms that link a transient neural activity to the corresponding increase of cerebral blood flow (CBF are termed neurovascular coupling (NVC. They are possibly impaired at early stage of small vessel or neurodegenerative diseases. Investigation of NVC in human has been made possible since the development of various neuroimaging techniques based on variations of local hemodynamics during neural activity. Specific dynamic models are currently used for interpreting these data that can include biophysical parameters related to NVC. We reviewed the seven models with explicit integration of NVC found in the literature and described their physiological assumption, mathematical formalism and validation. All models were described regarding a constant schematic formalism. Differences between them, particularly regarding their complexity, and hence, their potential use were finally evaluated. These models may provide key information to investigate various aspects of NVC in human pathology.

  11. Transition probability, dynamic regimes, and the critical point of financial crisis

    Science.gov (United States)

    Tang, Yinan; Chen, Ping

    2015-07-01

    An empirical and theoretical analysis of financial crises is conducted based on statistical mechanics in non-equilibrium physics. The transition probability provides a new tool for diagnosing a changing market. Both calm and turbulent markets can be described by the birth-death process for price movements driven by identical agents. The transition probability in a time window can be estimated from stock market indexes. Positive and negative feedback trading behaviors can be revealed by the upper and lower curves in transition probability. Three dynamic regimes are discovered from two time periods including linear, quasi-linear, and nonlinear patterns. There is a clear link between liberalization policy and market nonlinearity. Numerical estimation of a market turning point is close to the historical event of the US 2008 financial crisis.

  12. Introducing RFID technology in dynamic and time-critical medical settings: requirements and challenges.

    Science.gov (United States)

    Parlak, Siddika; Sarcevic, Aleksandra; Marsic, Ivan; Burd, Randall S

    2012-10-01

    We describe the process of introducing RFID technology in the trauma bay of a trauma center to support fast-paced and complex teamwork during resuscitation. We analyzed trauma resuscitation tasks, photographs of medical tools, and videos of simulated resuscitations to gain insight into resuscitation tasks, work practices and procedures. Based on these data, we discuss strategies for placing RFID tags on medical tools and for placing antennas in the environment for optimal tracking and activity recognition. Results from our preliminary RFID deployment in the trauma bay show the feasibility of our approach for tracking tools and for recognizing trauma team activities. We conclude by discussing implications for and challenges to introducing RFID technology in other similar settings characterized by dynamic and collocated collaboration. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Critical dynamics in the evolution of stochastic strategies for the iterated prisoner's dilemma.

    Science.gov (United States)

    Iliopoulos, Dimitris; Hintze, Arend; Adami, Christoph

    2010-10-07

    The observed cooperation on the level of genes, cells, tissues, and individuals has been the object of intense study by evolutionary biologists, mainly because cooperation often flourishes in biological systems in apparent contradiction to the selfish goal of survival inherent in Darwinian evolution. In order to resolve this paradox, evolutionary game theory has focused on the Prisoner's Dilemma (PD), which incorporates the essence of this conflict. Here, we encode strategies for the iterated Prisoner's Dilemma (IPD) in terms of conditional probabilities that represent the response of decision pathways given previous plays. We find that if these stochastic strategies are encoded as genes that undergo Darwinian evolution, the environmental conditions that the strategies are adapting to determine the fixed point of the evolutionary trajectory, which could be either cooperation or defection. A transition between cooperative and defective attractors occurs as a function of different parameters such as mutation rate, replacement rate, and memory, all of which affect a player's ability to predict an opponent's behavior. These results imply that in populations of players that can use previous decisions to plan future ones, cooperation depends critically on whether the players can rely on facing the same strategies that they have adapted to. Defection, on the other hand, is the optimal adaptive response in environments that change so quickly that the information gathered from previous plays cannot usefully be integrated for a response.

  14. Critical dynamics in the evolution of stochastic strategies for the iterated prisoner's dilemma.

    Directory of Open Access Journals (Sweden)

    Dimitris Iliopoulos

    Full Text Available The observed cooperation on the level of genes, cells, tissues, and individuals has been the object of intense study by evolutionary biologists, mainly because cooperation often flourishes in biological systems in apparent contradiction to the selfish goal of survival inherent in Darwinian evolution. In order to resolve this paradox, evolutionary game theory has focused on the Prisoner's Dilemma (PD, which incorporates the essence of this conflict. Here, we encode strategies for the iterated Prisoner's Dilemma (IPD in terms of conditional probabilities that represent the response of decision pathways given previous plays. We find that if these stochastic strategies are encoded as genes that undergo Darwinian evolution, the environmental conditions that the strategies are adapting to determine the fixed point of the evolutionary trajectory, which could be either cooperation or defection. A transition between cooperative and defective attractors occurs as a function of different parameters such as mutation rate, replacement rate, and memory, all of which affect a player's ability to predict an opponent's behavior. These results imply that in populations of players that can use previous decisions to plan future ones, cooperation depends critically on whether the players can rely on facing the same strategies that they have adapted to. Defection, on the other hand, is the optimal adaptive response in environments that change so quickly that the information gathered from previous plays cannot usefully be integrated for a response.

  15. Critically evaluated theoretical energies, lifetimes, static and dynamic polarizabilities, and magic wavelengths in cesium

    Science.gov (United States)

    Safronova, Marianna; Safronova, U. I.; Clark, Charles W.

    2016-05-01

    Systematic study of Cs atomic properties is carried out using a high-precision relativistic all-order method. Excitation energies of the ns , np , nd , and nf (n electric-dipole transitions. Electric-dipole (6 s - np , n = 6-26) and electric-quadrupole (6 s - ndj , n = 5-26) matrix elements are calculated to obtain the ground state E1 and E2 static polarizabilities. Scalar polarizabilities of the ns , np ,and nd states, and tensor polarizabilities of the np3 / 2 and ndj excited states of Cs are evaluated. These calculations provide recommended values critically evaluated for their accuracy for a number of Cs atomic properties useful for a variety of applications. Using first-principles calculations, we identify magic wavelengths λ for the 6 s - 7p1 / 2 and 6 s - 7p3 / 2 transitions in Cs. The ns and npj atomic levels have the same ac Stark shifts at the corresponding magic wavelength, which facilitates state-insensitive optical cooling and trapping.

  16. THE DETERMINATION OF A CRITICAL VALUE FOR DYNAMIC STABILITY OF SEMICONDUCTOR LASER DIODE WITH EXTERNAL OPTICAL FEEDBACK

    Directory of Open Access Journals (Sweden)

    Remzi YILDIRIM

    1998-01-01

    Full Text Available In this study, dynamic stability analysis of semiconductor laser diodes with external optical feedback has been realized. In the analysis the frequency response of the transfer function of laser diode H jw( , the transfer m function of laser diode with external optical feedback TF jw( , and optical feedback transfer function m K jw( obtained from small signal equations has been m accomplished using Nyquist stability analysis in complex domain. The effect of optical feedback on the stability of the system has been introduced and to bring the laser diode to stable condition the working critical boundary range of dampig frequency and reflection power constant (R has been determined. In the study the reflection power has been taken as ( .

  17. Transport Phenomena and Materials Processing

    Science.gov (United States)

    Kou, Sindo

    1996-10-01

    An extremely useful guide to the theory and applications of transport phenomena in materials processing This book defines the unique role that transport phenomena play in materials processing and offers a graphic, comprehensive treatment unlike any other book on the subject. The two parts of the text are, in fact, two useful books. Part I is a very readable introduction to fluid flow, heat transfer, and mass transfer for materials engineers and anyone not yet thoroughly familiar with the subject. It includes governing equations and boundary conditions particularly useful for studying materials processing. For mechanical and chemical engineers, and anyone already familiar with transport phenomena, Part II covers the many specific applications to materials processing, including a brief description of various materials processing technologies. Readable and unencumbered by mathematical manipulations (most of which are allocated to the appendixes), this book is also a useful text for upper-level undergraduate and graduate-level courses in materials, mechanical, and chemical engineering. It includes hundreds of photographs of materials processing in action, single and composite figures of computer simulation, handy charts for problem solving, and more. Transport Phenomena and Materials Processing: * Describes eight key materials processing technologies, including crystal growth, casting, welding, powder and fiber processing, bulk and surface heat treating, and semiconductor device fabrication * Covers the latest advances in the field, including recent results of computer simulation and flow visualization * Presents special boundary conditions for transport phenomena in materials processing * Includes charts that summarize commonly encountered boundary conditions and step-by-step procedures for problem solving * Offers a unique derivation of governing equations that leads to both overall and differential balance equations * Provides a list of publicly available computer

  18. Fast Particle Methods for Multiscale Phenomena Simulations

    Science.gov (United States)

    Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

    2000-01-01

    We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

  19. The critical end point through observables

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, G. [Joint Institute for Nuclear Research, Joliot-Curie st.6, Dubna, 141980 (Russian Federation)

    2016-01-22

    We develop the model of the critical phenomena of strongly interacting matter at high temperatures and baryon densities. The dual Yang-Mills theory with scalar degrees of freedom (the dilatons) is used. The dilatons are the consequence of a spontaneous breaking of a scale symmetry. The phase transitions are considered in systems where the field conjugate to the order parameter has the critical end mode. The critical end point (CEP) is a distinct singular feature existence of which is dictated by the chiral dynamics. The physical realization of CEP is via the influence quantum fluctuations of two-body Bose-Einstein correlations for observed particles to which the critical end mode couples.

  20. The hippocampal laminin matrix is dynamic and critical for neuronal survival.

    Science.gov (United States)

    Chen, Zu-Lin; Indyk, Justin A; Strickland, Sidney

    2003-07-01

    Laminins are extracellular matrix proteins that participate in neuronal development, survival, and regeneration. During excitotoxin challenge in the mouse hippocampus, neuron interaction with laminin-10 (alpha5,beta1,gamma1) protects against neuronal death. To investigate how laminin is involved in neuronal viability, we infused laminin-1 (alpha1,beta1,gamma1) into the mouse hippocampus. This infusion specifically disrupted the endogenous laminin layer. This disruption was at least partially due to the interaction of the laminin-1 gamma1 chain with endogenous laminin-10, because infusion of anti-laminin gamma1 antibody had the same effect. The disruption of the laminin layer by laminin-1 1) did not require the intact protein because infusion of plasmin-digested laminin-1 gave similar results; 2) was posttranscriptional, because there was no effect on laminin mRNA expression; and 3) occurred in both tPA(-/-) and plasminogen(-/-) mice, indicating that increased plasmin activity was not responsible. Finally, although tPA(-/-) mice are normally resistant to excitotoxin-induced neurodegeneration, disruption of the endogenous laminin layer by laminin-1 or anti-laminin gamma1 antibody renders the tPA(-/-) hippocampal neurons sensitive to kainate. These results demonstrate that neuron interactions with the deposited matrix are not necessarily recapitulated by interactions with soluble components and that the laminin matrix is a dynamic structure amenable to modification by exogenous molecules.