Mesoscale modeling of phase transition dynamics of thermoresponsive polymers
Li, Zhen; Li, Xuejin; Karniadakis, George Em
2015-01-01T23:59:59.000Z
We present a non-isothermal mesoscopic model for investigation of the phase transition dynamics of thermoresponsive polymers. Since this model conserves energy in the simulations, it is able to correctly capture not only the transient behavior of polymer precipitation from solvent, but also the energy variation associated with the phase transition process. Simulations provide dynamic details of the thermally induced phase transition and confirm two different mechanisms dominating the phase transition dynamics. A shift of endothermic peak with concentration is observed and the underlying mechanism is explored.
Comparison of bifurcation dynamics of turbulent transport models for the L-H transition
Weymiens, W., E-mail: w.weymiens@differ.nl; Blank, H. J. de; Hogeweij, G. M. D. [FOM Institute DIFFERDutch Institute for Fundamental Energy Research, Association EURATOM-FOM, PO Box 1207, Nieuwegein (Netherlands)] [FOM Institute DIFFERDutch Institute for Fundamental Energy Research, Association EURATOM-FOM, PO Box 1207, Nieuwegein (Netherlands); Paquay, S. [Department of Applied Physics, Eindhoven University of Technology, PO Box 503, Eindhoven (Netherlands)] [Department of Applied Physics, Eindhoven University of Technology, PO Box 503, Eindhoven (Netherlands)
2014-05-15T23:59:59.000Z
In more than three decades, a large amount of models and mechanisms have been proposed to describe a very beneficial feature of magnetically confined fusion plasmas: the L-H transition. Bifurcation theory can be used to compare these different models based on their dynamical transition structure. In this paper, we employ bifurcation theory to distinguish two fundamentally different descriptions of the interaction between turbulence levels and sheared flows. The analytic bifurcation analysis characterises the parameter space structure of the transition dynamics. Herewith, in these models three dynamically different types of transitions are characterised, sharp transitions, oscillatory transitions, and smooth transitions. One of the two models has a very robust transition structure and is therefore likely to be more accurate for such a robust phenomenon as the L-H transition. The other model needs more fine-tuning to get non-oscillatory transitions. These conclusions from the analytic bifurcation analysis are confirmed by dedicated numerical simulations, with the newly developed code Bifurcator.
Hammes-Schiffer, Sharon
Proton-coupled electron transfer reactions in solution: Molecular dynamics with quantum transitions A general minimal model for proton-coupled electron transfer PCET reactions in solution is presented. This model consists of three coupled degrees of freedom that represent an electron, a proton, and a solvent
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
market, allowing our model to focus on the supply of crude oil andterms of the model equations [7]). The oil market in ROMEO
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
and income on energy and oil demand. Energy Journal, 23(1):conventional oil supply and demand. But, interestingly,World crude oil and natural gas: a demand and supply model.
Kaper, Tasso J., E-mail: tasso@bu.edu; Kramer, Mark A., E-mail: mak@bu.edu [Department of Mathematics and Statistics, Boston University, Boston, Massachusetts 02215 (United States); Rotstein, Horacio G., E-mail: horacio@njit.edu [Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States)
2013-12-15T23:59:59.000Z
Rhythmic neuronal oscillations across a broad range of frequencies, as well as spatiotemporal phenomena, such as waves and bumps, have been observed in various areas of the brain and proposed as critical to brain function. While there is a long and distinguished history of studying rhythms in nerve cells and neuronal networks in healthy organisms, the association and analysis of rhythms to diseases are more recent developments. Indeed, it is now thought that certain aspects of diseases of the nervous system, such as epilepsy, schizophrenia, Parkinson's, and sleep disorders, are associated with transitions or disruptions of neurological rhythms. This focus issue brings together articles presenting modeling, computational, analytical, and experimental perspectives about rhythms and dynamic transitions between them that are associated to various diseases.
Finite temperature spin-dynamics and phase transitions in spin-orbital models
Chen, C.-C.
2010-04-29T23:59:59.000Z
We study finite temperature properties of a generic spin-orbital model relevant to transition metal compounds, having coupled quantum Heisenberg-spin and Ising-orbital degrees of freedom. The model system undergoes a phase transition, consistent with that of a 2D Ising model, to an orbitally ordered state at a temperature set by short-range magnetic order. At low temperatures the orbital degrees of freedom freeze-out and the model maps onto a quantum Heisenberg model. The onset of orbital excitations causes a rapid scrambling of the spin spectral weight away from coherent spin-waves, which leads to a sharp increase in uniform magnetic susceptibility just below the phase transition, reminiscent of the observed behavior in the Fe-pnictide materials.
Mechanochemical modeling of dynamic microtubule growth involving sheet-to-tube transition
Xiang-Ying Ji; Xi-Qiao Feng
2011-08-02T23:59:59.000Z
Microtubule dynamics is largely influenced by nucleotide hydrolysis and the resultant tubulin configuration changes. The GTP cap model has been proposed to interpret the stabilizing mechanism of microtubule growth from the view of hydrolysis effects. Besides, the microtubule growth involves the closure of a curved sheet at its growing end. The curvature conversion also helps to stabilize the successive growth, and the curved sheet is referred to as the conformational cap. However, there still lacks theoretical investigation on the mechanical-chemical coupling growth process of microtubules. In this paper, we study the growth mechanisms of microtubules by using a coarse-grained molecular method. Firstly, the closure process involving a sheet-to-tube transition is simulated. The results verify the stabilizing effect of the sheet structure, and the minimum conformational cap length that can stabilize the growth is demonstrated to be two dimers. Then, we show that the conformational cap can function independently of the GTP cap, signifying the pivotal role of mechanical factors. Furthermore, based on our theoretical results, we describe a Tetris-like growth style of microtubules: the stochastic tubulin assembly is regulated by energy and harmonized with the seam zipping such that the sheet keeps a practically constant length during growth.
Using System Dynamics to Model the Transition to Biofuels in the United States: Preprint
Bush, B.; Duffy, M.; Sandor, D.; Peterson, S.
2008-06-01T23:59:59.000Z
Transitioning to a biofuels industry that is expected to displace about 30% of current U.S. gasoline consumption requires a robust biomass-to-biofuels system-of-systems that operates in concert with the existing markets. This paper discusses employing a system dynamics approach to investigate potential market penetration scenarios for cellulosic ethanol and to help government decision makers focus on areas with greatest potential.
Guidoni, Leonardo
Hybrid Car-Parrinello/Molecular Mechanics Modelling of Transition Metal Complexes: Structure). We have recently developed a QM/MM extension of a Car-Parrinello scheme [5]. These hybrid Car functional theory embedded in a classical force field description. The power of such a combined Car
Paris-Sud XI, Université de
Transitional Modeling of Building Heating Energy Demand Using Artificial1 Neural Network2 Subodh Paudel a, it is39 essential to know energy flows and energy demand of the buildings for the control of heating and40 cooling energy production from plant systems. The energy demand of the building system, thus,41
Suman Chakrabarty; Dwaipayan Chakrabarti; Biman Bagchi
2006-03-14T23:59:59.000Z
Orientational dynamics in a liquid crystalline system near the isotropic-nematic (I-N) phase transition is studied using Molecular Dynamics simulations of the well-known Lebwohl-Lasher (LL) model. As the I-N transition temperature is approached from the isotropic side, we find that the decay of the orientational time correlation functions (OTCF) slows down noticeably, giving rise to a power law decay at intermediate timescales. The angular velocity time correlation function also exhibits a rather pronounced power law decay near the I-N boundary. In the mean squared angular displacement at comparable timescales, we observe the emergence of a \\emph{subdiffusive regime} which is followed by a \\emph{superdiffusive regime} before the onset of the long-time diffusive behavior. We observe signature of dynamical heterogeneity through \\emph{pronounced non-Gaussian behavior in orientational motion} particularly at lower temperatures. This behavior closely resembles what is usually observed in supercooled liquids. We obtain the free energy as a function of orientational order parameter by the use of transition matrix Monte Carlo method. The free energy surface is flat for the system considered here and the barrier between isotropic and nematic phases is vanishingly small for this weakly first-order phase transition, hence allowing large scale, collective and correlated orientational density fluctuations. This might be responsible for the observed power law decay of the OTCFs.
Gedeon, Tomas
, from those appearing in physiology and ecology to Earth systems modeling, often experience critical
Dynamical transitions of turing patterns.
Kaper, H. G.; Wang, S.; Yari, M.; Mathematics and Computer Science; Indiana Univ.
2009-01-01T23:59:59.000Z
This paper is concerned with the formation and persistence of spatiotemporal patterns in binary mixtures of chemically reacting species, where one of the species is an activator, the other an inhibitor of the chemical reaction. The system of reaction-diffusion equations is reduced to a finite system of ordinary differential equations by a variant of the centre-manifold reduction method. The reduced system fully describes the local dynamics of the original system near transition points at the onset of instability. The attractor-bifurcation theory is used to give a complete characterization of the bifurcated objects in terms of the physical parameters of the problem. The results are illustrated for the Schnakenberg model.
Using System Dynamics to Model the Transition to Biofuels in the United States
Bush, B.; Duffy, M.; Sandor, D.; Peterson, S.
2008-01-01T23:59:59.000Z
Today, the U.S. consumes almost 21 million barrels of crude oil per day; approximately 60% of the U.S. demand is supplied by imports. The transportation sector alone accounts for two-thirds of U.S. petroleum use. Biofuels, liquid fuels produced from domestically-grown biomass, have the potential to displace about 30% of current U.S. gasoline consumption. Transitioning to a biofuels industry on this scale will require the creation of a robust biomass-to-biofuels system-of-systems that operates in concert with the existing agriculture, forestry, energy, and transportation markets. The U.S. Department of Energy is employing a system dynamics approach to investigate potential market penetration scenarios for cellulosic ethanol, and to aid decision makers in focusing government actions on the areas with greatest potential to accelerate the deployment of biofuels and ultimately reduce the nationpsilas dependence on imported oil.
Phase Transition in Tensor Models
Delepouve, Thibault
2015-01-01T23:59:59.000Z
Generalizing matrix models, tensor models generate dynamical triangulations in any dimension and support a $1/N$ expansion. Using the intermediate field representation we explicitly rewrite a quartic tensor model as a field theory for a fluctuation field around a vacuum state corresponding to the resummation of the entire leading order in $1/N$ (a resummation of the melonic family). We then prove that the critical regime in which the continuum limit in the sense of dynamical triangulations is reached is precisely a phase transition in the field theory sense for the fluctuation field.
Energy Policy and Economics 021 "Dynamics of the Oil Transition
Kammen, Daniel M.
Energy Policy and Economics 021 "Dynamics of the Oil Transition: Modeling Capacity, Costs of the oil transition: modeling capacity, costs, and emissions Adam R. Brandt and Alexander E. Farrell Energy, and Emissions" Adam R. Brandt and Alexander E. Farrell Energy and Resources Group, University of California
Sitnov, Mikhail I.
, this exponent relates input and output parameters of the magnetosphere. Using an analogy to the dynamical Ising model in the mean-field approximation, we show the connection between the data-derived exponent in the flow of the plasma coming from the Sun solar wind . Part of the solar wind energy penetrates
Transition state theory: Variational formulation, dynamical corrections, and error estimates
Van Den Eijnden, Eric
Transition state theory: Variational formulation, dynamical corrections, and error estimates Eric, Brazil Received 18 February 2005; accepted 9 September 2005; published online 7 November 2005 Transition which aim at computing dynamical corrections to the TST transition rate constant. The theory
Dynamic Transitions of Surface Tension Driven Convection
Henk Dijkstra; Taylan Sengul; Shouhong Wang
2011-05-05T23:59:59.000Z
We study the well-posedness and dynamic transitions of the surface tension driven convection in a three-dimensional (3D) rectangular box with non-deformable upper surface and with free-slip boundary conditions. It is shown that as the Marangoni number crosses the critical threshold, the system always undergoes a dynamic transition. In particular, two different scenarios are studied. In the first scenario, a single mode losing its stability at the critical parameter gives rise to either a Type-I (continuous) or a Type-II (jump) transition. The type of transitions is dictated by the sign of a computable non-dimensional parameter, and the numerical computation of this parameter suggests that a Type-I transition is favorable. The second scenario deals with the case where the geometry of the domain allows two critical modes which possibly characterize a hexagonal pattern. In this case we show that the transition can only be either a Type-II or a Type-III (mixed) transition depending on another computable non-dimensional parameter. We only encountered Type-III transition in our numerical calculations. The second part of the paper deals with the well-posedness and existence of global attractors for the problem.
Supple, Derek R. (Derek Richard)
2007-01-01T23:59:59.000Z
Designing public policy or industry strategy to bolster the transition to alternative fuel vehicles (AFVs) is a formidable challenge as demonstrated by historical failed attempts. The transition to new fuels occurs within ...
Dynamics of stimulated L ? H transitions
Miki, K. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of) [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Center for Computational Science and e-Systems, Japan Atomic Energy Agency, Chiba 277-8587 (Japan); Diamond, P. H.; Xiao, W. W. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of) [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Center for Momentum Transport and Flow Organization, University of California, San Diego, California 92093 (United States); Hahn, S.-H. [KSTAR Team, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)] [KSTAR Team, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Grcan, . D. [LPP, Ecole Polytechnique, CNRS, 92118 Palaiseau Cedex (France)] [LPP, Ecole Polytechnique, CNRS, 92118 Palaiseau Cedex (France); Tynan, G. R. [Center for Momentum Transport and Flow Organization, University of California, San Diego, California 92093 (United States)] [Center for Momentum Transport and Flow Organization, University of California, San Diego, California 92093 (United States)
2013-08-15T23:59:59.000Z
We report on model studies of stimulated L ? H transitions [K. Miki et al., Phys. Rev. Lett. 110, 195002 (2013)]. These studies use a reduced mesoscale model. Model studies reveal that L ? H transition can be triggered by particle injection into a subcritical state (i.e., P
transition. For low ambient heating, strong injection is predicted to trigger a transient turbulence collapse. Repetitive injection at a period less than the lifetime of the collapsed state can thus maintain the turbulence collapse and so sustain a driven H-mode-like state. The total number of particles required to induce a transition by either injection or gas puffing is estimated. Results indicate that the total number of injected particles required is much smaller than that required for a transition by gas puffing. We thus show that internal injection is more efficient than gas puffing of comparable strength. We also observe that zonal flows do not play a critical role in stimulated transitions. For spontaneous transitions, the spike of the Reynolds work of turbulence on the zonal flow precedes the spike in the mean electric field shear. In contrast, we show that the two are coincident for stimulated transitions, suggesting that there is no causal link between zonal and mean flows for stimulated transitions.
Controlling dynamic contact transition for nonholonomic mobile manipulators
Boyer, Edmond
Controlling dynamic contact transition for nonholonomic mobile manipulators V. Padois and P. Chiron the Genom controller on the h2bis nonholonomic mobile manipulator. I. INTRODUCTION For many years, research proposed to deal with the control of mobile manipulators. Modeling issues can be found in [2], [4
Dynamical Transition and Heterogeneous Hydration Dynamics in RNA
Jeseong Yoon; Jong-Chin Lin; Changbong Hyeon; D. Thirumalai
2014-04-24T23:59:59.000Z
Enhanced dynamical fluctuations of RNAs, facilitated by a network of water molecules with strong interactions with RNA, are suspected to be critical in their ability to respond to a variety of cellular signals. Using atomically detailed molecular dynamics simulations at various temperatures of purine (adenine)- and preQ$_1$ sensing riboswitch aptamers, we show that water molecules in the vicinity of RNAs undergo complex dynamics depending on the local structures of the RNAs. The overall lifetimes of hydrogen bonds (HBs) of surface bound waters are more than at least 1-2 orders of magnitude longer than bulk water. Slow hydration dynamics, revealed in non-Arrhenius behavior of the relaxation time, arises from high activation barriers to break water hydrogen bonds with a nucleotide and by reduced diffusion of water. The relaxation kinetics at specific locations in the two RNAs show a broad spectrum of time scales reminiscent of glass-like behavior, suggesting that the hydration dynamics is highly heterogeneous. Both RNAs undergo dynamic transition at $T = T_D \\gtrsim 200$ K as assessed by the mean square fluctuation of hydrogen atoms $\\langle x^2\\rangle$, which undergoes an abrupt harmonic-to-anharmonic transition at $T_D$. The near universal value of $T_D$ found for these RNAs and previously for tRNA is strongly correlated with changes in hydration dynamics as $T$ is altered. Hierarchical dynamics of waters associated with the RNA surface, revealed in the motions of distinct classes of water with well-separated time scales, reflects the heterogeneous local environment on the molecular surface of RNA. At low temperatures slow water dynamics predominates over structural transitions. Our study demonstrates that the complex interplay of dynamics between water and local environment in the RNA structures could be a key determinant of the functional activities of RNA.
Ising model: secondary phase transition
You-gang Feng
2012-04-09T23:59:59.000Z
Lttice-spin phonons are considered, which make the heat capacity at the critical temperature satisfy experimental observations better. There is a BEC phase transition in an Ising model attributable to the lattice-spin phonons. We proved that the spin-wave theory only is available after BEC transition, and the magnons have the same characteristics as the lattice-spin phonons', resulting from quantum effect. Energy-level overlap effect at ultralow temperature is found. A prediction of BEC phase transition in a crystal is put forward as our theory generalization.
Queuing models System dynamics models
Glushko, Robert J.
models Value chain models Business Model / Organizational Perspective Process Perspective Information#12;#12;#12;#12;Queuing models System dynamics models #12;#12;#12;#12;Blueprint or touchpoint
Crossover transition in bag-like models
Ferroni, Lorenzo
2009-01-01T23:59:59.000Z
DE-AC02-05CH11231 Crossover transition in bag-like models L.We show that a crossover transition qualitatively similar toI. INTRODUCTION The phase transition of strongly interacting
Superadiabatic transition histories in quantum molecular dynamics
Volker Betz; Benjamin D. Goddard; Stefan Teufel
2009-02-03T23:59:59.000Z
We study the dynamics of a molecule's nuclear wave-function near an avoided crossing of two electronic energy levels, for one nuclear degree of freedom. We derive the general form of the Schroedinger equation in the n-th superadiabatic representation for all n, and give some partial results about the asymptotics for large n. Using these results, we obtain closed formulas for the time development of the component of the wave function in an initially unoccupied energy subspace, when a wave packet crosses the transition region. In the optimal superadiabatic representation, which we define, this component builds up monontonically. Finally, we give an explicit formula for the transition wave function away from the crossing, which is in excellent agreement with high precision numerical calculations.
The Dynamic Transition of Protein Hydration Water
W. Doster; S. Busch; A. M. Gaspar; M. -S. Appavou; J. Wuttke; H. Scheer
2010-02-12T23:59:59.000Z
Thin layers of water on biomolecular and other nanostructured surfaces can be supercooled to temperatures not accessible with bulk water. Chen et al. [PNAS 103, 9012 (2006)] suggested that anomalies near 220 K observed by quasi-elastic neutron scattering can be explained by a hidden critical point of bulk water. Based on more sensitive measurements of water on perdeuterated phycocyanin, using the new neutron backscattering spectrometer SPHERES, and an improved data analysis, we present results that show no sign of such a fragile-to-strong transition. The inflection of the elastic intensity at 220 K has a dynamic origin that is compatible with a calorimetric glass transition at 170 K. The temperature dependence of the relaxation times is highly sensitive to data evaluation; it can be brought into perfect agreement with the results of other techniques, without any anomaly.
Transition state theory and dynamical corrections in ergodic systems
Van Den Eijnden, Eric
Transition state theory and dynamical corrections in ergodic systems Fabio A. Tal and Eric Vanden, New York University, New York, USA Abstract. The results of transition state theory are derived manifold. A new perspective on how to compute the dynamical corrections to the TST transition frequency
Water-Peptide Dynamics during Conformational Transitions Dmitry Nerukh*,
Nerukh, Dmitry
Water-Peptide Dynamics during Conformational Transitions Dmitry Nerukh*, and Sergey Karabasov are investigated using classical molecular dynamics simulation with explicit water molecules. The distribution of the surrounding water at different moments before the transitions and the dynamical correlations of water
Electronic and structural dynamics in transition metal complexes...
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Electronic and structural dynamics in transition metal complexes - recent results from synchrotron and XFEL experiments Wednesday, March 4, 2015 - 3:00pm SLAC, Redtail Hawk...
Dynamic Phase Transition, Enhanced Reaction Rate, and
Rikvold, Per Arne
is a CO, they react [CO + O CO2(g)] These dynamical rules fully define the model. Its properties on a crystal surface by Langmuir-Hinshelwood mechanism: CO(g)+S CO(a) O2 + 2S 2O(a) CO(a) + O(a) CO2(g) + 2S been observed experimentally for high enough temperatures. Add CO desorption rate k to mimic
Dynamic Analysis of Fuel Cycle Transitioning
Brent Dixon; Steve Piet; David Shropshire; Gretchen Matthern
2009-09-01T23:59:59.000Z
This paper examines the time-dependent dynamics of transitioning from a once-through fuel cycle to a closed fuel cycle. The once-through system involves only Light Water Reactors (LWRs) operating on uranium oxide fuel UOX), while the closed cycle includes both LWRs and fast spectrum reactors (FRs) in either a single-tier system or two-tier fuel system. The single-tier system includes full transuranic recycle in FRs while the two-tier system adds one pass of mixed oxide uranium-plutonium (MOX U-Pu) fuel in the LWR. While the analysis primarily focuses on burner fast reactors, transuranic conversion ratios up to 1.0 are assessed and many of the findings apply to any fuel cycle transitioning from a thermal once-through system to a synergistic thermal-fast recycle system. These findings include uranium requirements for a range of nuclear electricity growth rates, the importance of back end fuel cycle facility timing and magnitude, the impact of employing a range of fast reactor conversion ratios, system sensitivity to used fuel cooling time prior to recycle, impacts on a range of waste management indicators, and projected electricity cost ranges for once-through, single-tier and two-tier systems. The study confirmed that significant waste management benefits can be realized as soon as recycling is initiated, but natural uranium savings are minimal in this century. The use of MOX in LWRs decouples the development of recycle facilities from fast reactor fielding, but also significantly delays and limits fast reactor deployment. In all cases, fast reactor deployment was significantly below than predicted by static equilibrium analyses.
Protein viscoelastic dynamics: a model system
Craig Fogle; Joseph Rudnick; David Jasnow
2015-02-02T23:59:59.000Z
A model system inspired by recent experiments on the dynamics of a folded protein under the influence of a sinusoidal force is investigated and found to replicate many of the response characteristics of such a system. The essence of the model is a strongly over-damped oscillator described by a harmonic restoring force for small displacements that reversibly yields to stress under sufficiently large displacement. This simple dynamical system also reveals unexpectedly rich behavior, exhibiting a series of dynamical transitions and analogies with equilibrium thermodynamic phase transitions. The effects of noise and of inertia are briefly considered and described.
Bifurcation analysis and dimension reduction of a predator-prey model for the L-H transition
Dam, Magnus; Brns, Morten [Department of Applied Mathematics and Computer Science, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)] [Department of Applied Mathematics and Computer Science, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Juul Rasmussen, Jens; Naulin, Volker [Association Euratom-DTU, Department of Physics, Technical University of Denmark, DTU Ris Campus, DK-4000 Roskilde (Denmark)] [Association Euratom-DTU, Department of Physics, Technical University of Denmark, DTU Ris Campus, DK-4000 Roskilde (Denmark); Xu, Guosheng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)] [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
2013-10-15T23:59:59.000Z
The L-H transition denotes a shift to an improved confinement state of a toroidal plasma in a fusion reactor. A model of the L-H transition is required to simulate the time dependence of tokamak discharges that include the L-H transition. A 3-ODE predator-prey type model of the L-H transition is investigated with bifurcation theory of dynamical systems. The analysis shows that the model contains three types of transitions: an oscillating transition, a sharp transition with hysteresis, and a smooth transition. The model is recognized as a slow-fast system. A reduced 2-ODE model consisting of the full model restricted to the flow on the critical manifold is found to contain all the same dynamics as the full model. This means that all the dynamics in the system is essentially 2-dimensional, and a minimal model of the L-H transition could be a 2-ODE model.
Chaotic Dynamics in Multidimensional Transition States Ali Allahem1, a)
Chaotic Dynamics in Multidimensional Transition States Ali Allahem1, a) and Thomas Bartsch1, b consequences of normal hyperbolicity20,21 : a)Electronic mail: a.allahem@lboro.ac.uk b)Electronic mail: t.bartsch
Euclidean Dynamical Symmetry in Nuclear Shape Phase Transitions
Yu Zhang; Yu-Xin Liu; Feng Pan; Yang Sun; J. P. Draayer
2014-11-26T23:59:59.000Z
The Euclidean dynamical symmetry hidden in the critical region of nuclear shape phase transitions is revealed by a novel algebraic F(5) description. With a nonlinear projection, it is shown that the dynamics in the critical region of the spherical--axial deformed and the spherical--$\\gamma$ soft shape phase transitions can indeed be manifested by this description, which thus provides a unified symmetry--based interpretation of the critical phenomena in the region.
Calorimetric glass transition explained by hierarchical dynamic facilitation
Garrahan, Juan P.
Calorimetric glass transition explained by hierarchical dynamic facilitation Aaron S. Keysa Contributed by David Chandler, February 11, 2013 (sent for review November 15, 2012) The glass transition different on cooling than on heating, and the response to melting a glass depends markedly on the cooling
Greenberg-Hastings dynamics on a small-world network: the collective extinct-active transition
Reyes, Leonardo I
2015-01-01T23:59:59.000Z
We present a numerical study of a reaction-diffusion model on a small-world network. We focus on the transition from a collective (global) extinct state to an active state in parameter space, and provide an explicit relation between the parameters of our model at the frontier between these states. The collective extinct-active transition can be induced by changing the parameters associated to the network: it's mean coordination number $K$ and the disorder parameter $p$ (which controls the variance of $K$). We can also induce the transition by changing the transmission probability $r$, which controls the threshold size in the dynamics. We find that, in order to stay at the transition, to increase disorder in the network is equivalent to increase the critical threshold size. Our results are relevant for systems that operate {\\it at} the transition in order to increase its dynamic range and/or to operate under optimal information-processing conditions.
Decoherence in a dynamical quantum phase transition
Sarah Mostame; Gernot Schaller; Ralf Schtzhold
2010-04-15T23:59:59.000Z
Motivated by the similarity between adiabatic quantum algorithms and quantum phase transitions, we study the impact of decoherence on the sweep through a second-order quantum phase transition for the prototypical example of the Ising chain in a transverse field and compare it to the adiabatic version of Grovers search algorithm, which displays a first order quantum phase transition. For site-independent and site-dependent coupling strengths as well as different operator couplings, the results show that (in contrast to first-order transitions) the impact of decoherence caused by a weak coupling to a rather general environment increases with system size (i.e., number of spins/qubits). This might limit the scalability of the corresponding adiabatic quantum algorithm.
A Simple, Accurate Model for Alkyl Adsorption on Late Transition...
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Simple, Accurate Model for Alkyl Adsorption on Late Transition Metals. A Simple, Accurate Model for Alkyl Adsorption on Late Transition Metals. Abstract: A simple model that...
Agent-Based Modeling and Simulation for Hydrogen Transition Analysis...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Agent-Based Modeling and Simulation for Hydrogen Transition Analysis Agent-Based Modeling and Simulation for Hydrogen Transition Analysis Presentation on Agent-Based Modeling and...
Dynamics in the Metabasin Space of a Lennard-Jones Glass Former: Connectivity and Transition Rates
Yasheng Yang; Bulbul Chakraborty
2008-11-17T23:59:59.000Z
Using simulations, we construct the effective dynamics in metabasin space for a Lennard-Jones glass-former. Metabasins are identified via a scheme that measures transition rates between inherent structures, and generates clusters of inherent structures by drawing in branches that have the largest transition rates. The effective dynamics is shown to be Markovian but differs significantly from the simplest trap models. We specifically show that retaining information about the connectivity in metabasin space is crucial for reproducing the slow dynamics observed in this system.
Geometrical Dynamics in a Transitioning Superconducting Sphere
James R. Claycomb; Rambis K. Chu
2006-02-22T23:59:59.000Z
Recent theoretical work has concentrated on calculating the Casimir effect in curved spacetime. In this paper we outline the forward problem of metrical variation due to the Casimir effect for spherical geometries. We consider a scalar quantum field inside a hollow superconducting sphere. Metric equations are developed describing the evolution of the scalar curvature after the sphere transitions to the normal state.
Integrated Market Modeling of Hydrogen Transition Scenarios with...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Integrated Market Modeling of Hydrogen Transition Scenarios with HyTrans Integrated Market Modeling of Hydrogen Transition Scenarios with HyTrans Presentation by Paul Leiby of Oak...
Modal aerosol dynamics modeling
Whitby, E.R.; McMurry, P.H.; Shankar, U.; Binkowski, F.S.
1991-02-01T23:59:59.000Z
The report presents the governing equations for representing aerosol dynamics, based on several different representations of the aerosol size distribution. Analytical and numerical solution techniques for these governing equations are also reviewed. Described in detail is a computationally efficient numerical technique for simulating aerosol behavior in systems undergoing simultaneous heat transfer, fluid flow, and mass transfer in and between the gas and condensed phases. The technique belongs to a general class of models known as modal aerosol dynamics (MAD) models. These models solve for the temporal and spatial evolution of the particle size distribution function. Computational efficiency is achieved by representing the complete aerosol population as a sum of additive overlapping populations (modes), and solving for the time rate of change of integral moments of each mode. Applications of MAD models for simulating aerosol dynamics in continuous stirred tank aerosol reactors and flow aerosol reactors are provided. For the application to flow aerosol reactors, the discussion is developed in terms of considerations for merging a MAD model with the SIMPLER routine described by Patankar (1980). Considerations for incorporating a MAD model into the U.S. Environmental Protection Agency's Regional Particulate Model are also described. Numerical and analytical techniques for evaluating the size-space integrals of the modal dynamics equations (MDEs) are described. For multimodal logonormal distributions, an analytical expression for the coagulation integrals of the MDEs, applicable for all size regimes, is derived, and is within 20% of accurate numerical evaluation of the same moment coagulation integrals. A computationally efficient integration technique, based on Gauss-Hermite numerical integration, is also derived.
Quantum Phase Transition in a Graphene Model
Simon Hands; Costas Strouthos
2008-08-20T23:59:59.000Z
We present results for the equation of state of a graphene-like model in an effort to understand the properties of its quantum phase transition. The N_f fermion species interact through a three dimensional instantaneous Coulomb potential. Since there are no reliable analytical tools that work for all values of N_f and the coupling constant g, we rely on Monte Carlo simulations to calculate the critical properties of the model near the phase transition. We consider the four-component formulation for the fermion fields, which arises naturally as the continuum limit of the staggered fermion construction in (2+1) dimensions. In the limit of infinitely strong Coulomb interaction, the system undergoes a quantum phase transition at a critical number of fermion species N_fc ~ 4.7. We also calculate the values of the critical exponents at the quantum phase transition.
Cajahuaringa, Samuel; Koning, Maurice de, E-mail: dekoning@ifi.unicamp.br; Antonelli, Alex, E-mail: aantone@ifi.unicamp.br [Instituto de Fsica Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, So Paulo (Brazil)] [Instituto de Fsica Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, So Paulo (Brazil)
2013-12-14T23:59:59.000Z
Using molecular dynamics simulations we analyze the dynamics of two atomic liquids that display a liquid-liquid phase transition (LLPT): Si described by the Stillinger-Weber potential and Ga as modeled by the modified embedded-atom model. In particular, our objective is to investigate the extent to which the presence of a dip in the self-intermediate scattering function is a manifestation of an excess of vibrational states at low frequencies and may be associated with a fragile-to-strong transition (FTST) across the LLPT, as suggested recently. Our results suggest a somewhat different picture. First, in the case of Ga we observe the appearance of an excess of vibrational states at low frequencies, even in the absence of the appearance of a dip in the self-intermediate scattering function across the LLPT. Second, studying the behavior of the shear viscosities traversing the LLPTs we find that both substances are fragile in character above and below their respective LLPT temperatures. Instead of a FTST in an absolute sense these findings are more in line with a view in which the LLPTs are accompanied by a transition from a more fragile to a less fragile liquid. Furthermore, we do not find this transition to correlate with the presence of a dip in the intermediate scattering function.
Tools for dynamic model development
Schaber, Spencer Daniel
2014-01-01T23:59:59.000Z
For this thesis, several tools for dynamic model development were developed and analyzed. Dynamic models can be used to simulate and optimize the behavior of a great number of natural and engineered systems, from the ...
Mesoscale ocean dynamics modeling
mHolm, D.; Alber, M.; Bayly, B.; Camassa, R.; Choi, W.; Cockburn, B.; Jones, D.; Lifschitz, A.; Margolin, L.; Marsden, L.; Nadiga, B.; Poje, A.; Smolarkiewicz, P. [Los Alamos National Lab., NM (United States); Levermore, D. [Arizona Univ., Tucson, AZ (United States)
1996-05-01T23:59:59.000Z
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The ocean is a very complex nonlinear system that exhibits turbulence on essentially all scales, multiple equilibria, and significant intrinsic variability. Modeling the ocean`s dynamics at mesoscales is of fundamental importance for long-time-scale climate predictions. A major goal of this project has been to coordinate, strengthen, and focus the efforts of applied mathematicians, computer scientists, computational physicists and engineers (at LANL and a consortium of Universities) in a joint effort addressing the issues in mesoscale ocean dynamics. The project combines expertise in the core competencies of high performance computing and theory of complex systems in a new way that has great potential for improving ocean models now running on the Connection Machines CM-200 and CM-5 and on the Cray T3D.
Transitional solar dynamics, cosmic rays and global warming
A. Bershadskii
2009-04-12T23:59:59.000Z
Solar activity is studied using a cluster analysis of the time-fluctuations of the sunspot number. It is shown that in an Historic period the high activity components of the solar cycles exhibit strong clustering, whereas in a Modern period (last seven solar cycles: 1933-2007) they exhibit a white-noise (non-)clustering behavior. Using this observation it is shown that in the Historic period, emergence of the sunspots in the solar photosphere was strongly dominated by turbulent photospheric convection. In the Modern period, this domination was broken by a new more active dynamics of the inner layers of the convection zone. Then, it is shown that the dramatic change of the sun dynamics at the transitional period (between the Historic and Modern periods, solar cycle 1933-1944yy) had a clear detectable impact on Earth climate. A scenario of a chain of transitions in the solar convective zone is suggested in order to explain the observations, and a forecast for the global warming is suggested on the basis of this scenario. A relation between the recent transitions and solar long-period chaotic dynamics has been found. Contribution of the galactic turbulence (due to galactic cosmic rays) has been discussed. These results are also considered in a content of chaotic climate dynamics at millennial timescales.
Microgravity Flow Regime Transition Modeling
Shephard, Adam M.
2010-07-14T23:59:59.000Z
................... 18 14 Colin and Fabre (1995) 0.0190 m diameter air-water data set ................... 18 15 Comparison of the Dukler et al. (1988) and Bousman (1994) 0.0127 m diameter air-water system data sets... ........................................................................................................ 67 33 Colin and Fabre (1995) 0.0190 m diameter air-water data set with models ........................................................................................................ 68 34 Dukler et al. (1988) 0.0127 m diameter air-water data...
Microgravity Flow Regime Transition Modeling
Shephard, Adam M.
2010-07-14T23:59:59.000Z
by Ghrist (2008) where an existing computer code, RELAP 5-3D, demonstrated the limitations of currently available computational modeling when applied to zero-g conditions. 1.2.2 EXPERIMENTAL APPARATUS All flow regime mapping experiments consist of a... ............................................................... 9 2.3 Dukler et al. 1988/Janicot 1988 ............................................. 9 2.4 Colin et al. 1991 .................................................................... 11 2.5 Huckerby and Rezkallah 1992...
Testing Transition State Theory on Kac-Zwanzig Model
Van Den Eijnden, Eric
Testing Transition State Theory on Kac-Zwanzig Model G. Ariel and E. Vanden-Eijnden Courant A variant of the Kac-Zwanzig model is used to test the prediction of transition state theory (TST) and variational transition state theory (VTST). The model describes the evolution of a distinguished particle
Development of a Dynamic DOE Calibration Model
Broader source: Energy.gov (indexed) [DOE]
cell characterization * Train and validate dynamic models * Apply models for system optimization Results * Dynamic emissions models have been developed (validation error on the...
Ultrafast dynamics of the laser-induced solid-to-liquid phase transition in aluminum
Mazur, Eric
Ultrafast dynamics of the laser-induced solid-to-liquid phase transition in aluminum A thesis dynamics of the laser-induced solid-to-liquid phase transition in aluminum Eric Mazur Maria Kandyla Abstract This dissertation reports the ultrafast dynamics of aluminum during the solid-to- liquid phase
ARCHITECTURE AND DYNAMICS OF KEPLER'S CANDIDATE MULTIPLE TRANSITING PLANET SYSTEMS
Lissauer, Jack J.; Jenkins, Jon M.; Borucki, William J.; Bryson, Stephen T.; Howell, Steve B. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Ragozzine, Darin; Holman, Matthew J.; Carter, Joshua A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Fabrycky, Daniel C.; Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Steffen, Jason H. [Fermilab Center for Particle Astrophysics, Batavia, IL 60510 (United States); Ford, Eric B. [211 Bryant Space Science Center, University of Florida, Gainesville, FL 32611 (United States); Shporer, Avi [Las Cumbres Observatory Global Telescope Network, Santa Barbara, CA 93117 (United States); Rowe, Jason F.; Quintana, Elisa V.; Caldwell, Douglas A. [SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Batalha, Natalie M. [Department of Physics and Astronomy, San Jose State University, San Jose, CA 95192 (United States); Ciardi, David [Exoplanet Science Institute/Caltech, Pasadena, CA 91125 (United States); Dunham, Edward W. [Lowell Observatory, Flagstaff, AZ 86001 (United States); Gautier, Thomas N. III, E-mail: Jack.Lissauer@nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); and others
2011-11-01T23:59:59.000Z
About one-third of the {approx}1200 transiting planet candidates detected in the first four months of Kepler data are members of multiple candidate systems. There are 115 target stars with two candidate transiting planets, 45 with three, 8 with four, and 1 each with five and six. We characterize the dynamical properties of these candidate multi-planet systems. The distribution of observed period ratios shows that the vast majority of candidate pairs are neither in nor near low-order mean-motion resonances. Nonetheless, there are small but statistically significant excesses of candidate pairs both in resonance and spaced slightly too far apart to be in resonance, particularly near the 2:1 resonance. We find that virtually all candidate systems are stable, as tested by numerical integrations that assume a nominal mass-radius relationship. Several considerations strongly suggest that the vast majority of these multi-candidate systems are true planetary systems. Using the observed multiplicity frequencies, we find that a single population of planetary systems that matches the higher multiplicities underpredicts the number of singly transiting systems. We provide constraints on the true multiplicity and mutual inclination distribution of the multi-candidate systems, revealing a population of systems with multiple super-Earth-size and Neptune-size planets with low to moderate mutual inclinations.
Guido Tiana; Carlo Camilloni
2012-07-05T23:59:59.000Z
The atomistic characterization of the transition state is a fundamental step to improve the understanding of the folding mechanism and the function of proteins. From a computational point of view, the identification of the conformations that build out the transition state is particularly cumbersome, mainly because of the large computational cost of generating a statistically-sound set of folding trajectories. Here we show that a biasing algorithm, based on the physics of the ratchet-and-pawl, can be used to identify efficiently the transition state. The basic idea is that the algorithmic ratchet exerts a force on the protein when it is climbing the free-energy barrier, while it is inactive when it is descending. The transition state can be identified as the point of the trajectory where the ratchet changes regime. Besides discussing this strategy in general terms, we test it within a protein model whose transition state can be studied independently by plain molecular dynamics simulations. Finally, we show its power in explicit-solvent simulations, obtaining and characterizing a set of transition--state conformations for ACBP and CI2.
Glass transition line in C60: a mode-coupling/molecular-dynamics study
D. Costa; R. Ruberto; F. Sciortino; M. C. Abramo; C. Caccamo
2007-03-22T23:59:59.000Z
We report a study of the mode-coupling theory (MCT) glass transition line for the Girifalco model of C60 fullerene. The equilibrium static structure factor of the model, the only required input for the MCT calculations, is provided by molecular dynamics simulations. The glass transition line develops inside the metastable liquid-solid coexistence region and extends down in temperature, terminating on the liquid sideof the metastable portion of the liquid-vapor binodal. The vitrification locus does not show re-entrant behavior. A comparison with previous computer simulation estimates of the location of the glass line suggests that the theory accurately reproduces the shape of the arrest line in the density-temperature plane. The theoretical HNC and MHNC structure factors (and consequently the corresponding MCT glass line) compare well with the numerical counterpart. These evidences confirm the conclusion drawn in previous works about the existence of a glassy phase for the fullerene model at issue.
Agent-Based Modeling and Simulation for Hydrogen Transition Analysis
Broader source: Energy.gov [DOE]
Presentation on Agent-Based Modeling and Simulation for Hydrogen Transition Analysis given by Marianne Mintz of ANL during the DOE Hydrogen Transition Analysis Workshop on January 26, 2006.
Statistical mechanics model for the transit free energy of monatomic liquids
Duane C. Wallace; Eric D. Chisolm; N. Bock; G. De Lorenzi-Venneri
2010-04-19T23:59:59.000Z
In applying Vibration-Transit (V-T) theory of liquid dynamics to the thermodynamic properties of monatomic liquids, the point has been reached where an improved model is needed for the small (approx. 10%) transit contribution. Toward this goal, an analysis of the available high-temperature experimental entropy data for elemental liquids was recently completed [D. C. Wallace, E. D. Chisolm, and N. Bock, Phys. Rev. B 79, 051201 (2009)]. This analysis yields a common curve of transit entropy vs. T/\\theta_{tr}, where T is temperature and \\theta_{tr} is a scaling temperature for each element. In the present paper, a statistical mechanics model is constructed for the transit partition function, and is calibrated to the experimental transit entropy curve. The model has two scalar parameters, and captures the temperature scaling of experiment. The calibrated model fits the experimental liquid entropy to high accuracy at all temperatures. With no additional parameters, the model also agrees with both experiment and molecular dynamics for the internal energy vs. T for Na. With the calibrated transit model, V-T theory provides equations subject to ab initio evaluation for thermodynamic properties of monatomic liquids. This will allow the range of applicability of the theory, and its overall accuracy, to be determined. More generally, the hypothesis of V-T theory, which divides the many-atom potential energy valleys into random and symmetric classes, can also be tested for its application beyond monatomic systems.
Hammes-Schiffer, Sharon
Nonadiabatic transition state theory and multiple potential energy surface molecular dynamics in the vicinity of the energy barrier, i.e., in the region of the transition state or bottleneck. In general, TST 07974 Received 7 July 1995; accepted 17 August 1995 Classical transition state theory TST provides
Modeling-Computer Simulations At Walker-Lane Transitional Zone...
navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Modeling-Computer Simulations At Walker-Lane Transitional Zone Region (Biasi, Et Al., 2009) Exploration...
Modeling-Computer Simulations At Walker-Lane Transitional Zone...
navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Modeling-Computer Simulations At Walker-Lane Transitional Zone Region (Pritchett, 2004) Exploration...
Femtosecond Transition-State Dynamics of Dissociating OCS on the Excited 1+ Potential Energy Surface
Liu, Shilin
Femtosecond Transition-State Dynamics of Dissociating OCS on the Excited 1+ Potential Energy photodissociation dynamics of OCS on the dissociative potential energy surface (PES) of the electronically excited 1 calculations. The high-resolution PHOFEX spectrum of the entire 1+-1+ transition (63 300-69 350 cm-1
An improved model for the transit entropy of monatomic liquids
Wallace, Duane C [Los Alamos National Laboratory; Chisolm, Eric D [Los Alamos National Laboratory; Bock, Nicolas [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
In the original formulation of V-T theory for monatomic liquid dynamics, the transit contribution to entropy was taken to be a universal constant, calibrated to the constant-volume entropy of melting. This model suffers two deficiencies: (a) it does not account for experimental entropy differences of {+-}2% among elemental liquids, and (b) it implies a value of zero for the transit contribution to internal energy. The purpose of this paper is to correct these deficiencies. To this end, the V-T equation for entropy is fitted to an overall accuracy of {+-}0.1% to the available experimental high temperature entropy data for elemental liquids. The theory contains two nuclear motion contributions: (a) the dominant vibrational contribution S{sub vib}(T/{theta}{sub 0}), where T is temperature and {theta}{sub 0} is the vibrational characteristic temperature, and (b) the transit contribution S{sub tr}(T/{theta}{sub tr}), where {theta}{sub tr} is a scaling temperature for each liquid. The appearance of a common functional form of S{sub tr} for all the liquids studied is a property of the experimental data, when analyzed via the V-T formula. The resulting S{sub tr} implies the correct transit contribution to internal energy. The theoretical entropy of melting is derived, in a single formula applying to normal and anomalous melting alike. An ab initio calculation of {theta}{sub 0}, based on density functional theory, is reported for liquid Na and Cu. Comparison of these calculations with the above analysis of experimental entropy data provides verification of V-T theory. In view of the present results, techniques currently being applied in ab initio simulations of liquid properties can be employed to advantage in the further testing and development of V-T theory.
Global quantum discord and quantum phase transition in XY model
Si-Yuan Liu; Yu-Ran Zhang; Wen-Li Yang; Heng Fan
2014-05-20T23:59:59.000Z
We study the relationship between the behavior of global quantum correlations and quantum phase transitions in XY model. We find that the two kinds of phase transitions in the studied model can be characterized by the features of global quantum discord (GQD) and the corresponding quantum correlations. We demonstrate that the maximum of the sum of all the nearest neighbor bipartite GQDs is effective and accurate for signaling the Ising quantum phase transition, in contrast, the sudden change of GQD is very suitable for characterizing another phase transition in the XY model. This may shed lights on the study of properties of quantum correlations in different quantum phases.
Implementing SPC in a Simulation Model for Manufacturing Transitions
Nembhard, Harriet Black
- ~(~-;::;: Implementing SPC in a Simulation Model for Manufacturing Transitions Harriet Black and 2). Product quality often suffers during such transition periods. Statistical process control (SPC the design and development of an integrated SPC and simulation model. Figure 1 shows a screen snapshot
DYNAMIC MODELING FUEL PROCESSORS
Mease, Kenneth D.
turbine module (compressor and turbine sub-modules) Catalytic oxidizer Combustor module Heat exchanger, PEM, Gas Turbine General Model Assumptions 1D process flow Well-stirred within nodal volume Slow reactants #12;Steam Reformation Occurs in Reformer and Fuel Cells Methane reformation reaction Water Gas
Electroweak phase transition in a model with gauged lepton number
Alfredo Aranda; Enrique Jimnez; Carlos A. Vaquera-Araujo
2015-01-16T23:59:59.000Z
In this work we study the electroweak phase transition in a model with gauged lepton number. Here, a family of vector-like leptons is required in order to cancel the gauge anomalies. Furthermore, these leptons can play an important role in the transition process. We find that this framework is able to provide a strong transition, but only for a very limited number of cases.
LECTURES ON GLAUBER DYNAMICS FOR DISCRETE SPIN MODELS
Transitions 5.1 The SolidonSolid Approximation 5.2 Back to the Ising Model 5.3 Recent Progresses 6. Phase Measures 2.3 Weak and Strong Mixing Conditions 2.4 Mixing properties and bounds on relative densities 3 on the Spectral Gap with Free B.C 6.6 Mixed B.C 6.7 Applications 7. Glauber Dynamics for the Dilute Ising Model 7
Tobias Rindlisbacher; Philippe de Forcrand
2015-03-12T23:59:59.000Z
The transition between the two phases of 4D Euclidean Dynamical Triangulation [1] was long believed to be of second order until in 1996 first order behavior was found for sufficiently large systems [5,9]. However, one may wonder if this finding was affected by the numerical methods used: to control volume fluctuations, in both studies [5,9] an artificial harmonic potential was added to the action; in [9] measurements were taken after a fixed number of accepted instead of attempted moves which introduces an additional error. Finally the simulations suffer from strong critical slowing down which may have been underestimated. In the present work, we address the above weaknesses: we allow the volume to fluctuate freely within a fixed interval; we take measurements after a fixed number of attempted moves; and we overcome critical slowing down by using an optimized parallel tempering algorithm [12]. With these improved methods, on systems of size up to 64k 4-simplices, we confirm that the phase transition is first order. In addition, we discuss a local criterion to decide whether parts of a triangulation are in the elongated or crumpled state and describe a new correspondence between EDT and the balls in boxes model. The latter gives rise to a modified partition function with an additional, third coupling. Finally, we propose and motivate a class of modified path-integral measures that might remove the metastability of the Markov chain and turn the phase transition into second order.
Tobias Rindlisbacher; Philippe de Forcrand
2015-06-10T23:59:59.000Z
The transition between the two phases of 4D Euclidean Dynamical Triangulation [1] was long believed to be of second order until in 1996 first order behavior was found for sufficiently large systems [5,9]. However, one may wonder if this finding was affected by the numerical methods used: to control volume fluctuations, in both studies [5,9] an artificial harmonic potential was added to the action; in [9] measurements were taken after a fixed number of accepted instead of attempted moves which introduces an additional error. Finally the simulations suffer from strong critical slowing down which may have been underestimated. In the present work, we address the above weaknesses: we allow the volume to fluctuate freely within a fixed interval; we take measurements after a fixed number of attempted moves; and we overcome critical slowing down by using an optimized parallel tempering algorithm [12]. With these improved methods, on systems of size up to 64k 4-simplices, we confirm that the phase transition is first order. In addition, we discuss a local criterion to decide whether parts of a triangulation are in the elongated or crumpled state and describe a new correspondence between EDT and the balls in boxes model. The latter gives rise to a modified partition function with an additional, third coupling. Finally, we propose and motivate a class of modified path-integral measures that might remove the metastability of the Markov chain and turn the phase transition into second order.
Olsson, Peter
Transition in the two-dimensional step model: A Kosterlitz-Thouless transition in disguise Peter Received 19 October 2000; published 11 January 2001 Evidence for a Kosterlitz-Thouless transition in the spin angles. We conclude that this is the reason for the Kosterlitz- Thouless transition in the 2D step
The Electroweak Phase Transition in the Inert Doublet Model
Nikita Blinov; Stefano Profumo; Tim Stefaniak
2015-04-22T23:59:59.000Z
We study the strength of a first-order electroweak phase transition in the Inert Doublet Model (IDM), where particle dark matter (DM) is comprised of the lightest neutral inert Higgs boson. We improve over previous studies in the description and treatment of the finite-temperature effective potential and of the electroweak phase transition. We focus on a set of benchmark models inspired by the key mechanisms in the IDM leading to a viable dark matter particle candidate, and illustrate how to enhance the strength of the electroweak phase transition by adjusting the masses of the yet undiscovered IDM Higgs states. We argue that across a variety of DM masses, obtaining a strong enough first-order phase transition is a generic possibility in the IDM. We find that due to direct dark matter searches and collider constraints, a sufficiently strong transition and a thermal relic density matching the universal DM abundance is possible only in the Higgs funnel regime.
The Electroweak Phase Transition in the Inert Doublet Model
Blinov, Nikita; Stefaniak, Tim
2015-01-01T23:59:59.000Z
We study the strength of a first-order electroweak phase transition in the Inert Doublet Model (IDM), where particle dark matter (DM) is comprised of the lightest neutral inert Higgs boson. We improve over previous studies in the description and treatment of the finite-temperature effective potential and of the electroweak phase transition. We focus on a set of benchmark models inspired by the key mechanisms in the IDM leading to a viable dark matter particle candidate, and illustrate how to enhance the strength of the electroweak phase transition by adjusting the masses of the yet undiscovered IDM Higgs states. We argue that across a variety of DM masses, obtaining a strong enough first-order phase transition is a generic possibility in the IDM. We find that due to direct dark matter searches and collider constraints, a sufficiently strong transition and a thermal relic density matching the universal DM abundance is possible only in the Higgs funnel regime.
Rounding of the localization transition in model porous media
Simon K. Schnyder; Markus Spanner; Felix Hfling; Thomas Franosch; Jrgen Horbach
2014-11-07T23:59:59.000Z
The generic mechanisms of anomalous transport in porous media are investigated by computer simulations of two-dimensional model systems. In order to bridge the gap between the strongly idealized Lorentz model and realistic models of porous media, two models of increasing complexity are considered: a cherry-pit model with hard-core correlations as well as a soft-potential model. An ideal gas of tracer particles inserted into these structures is found to exhibit anomalous transport which extends up to several decades in time. Also, the self-diffusion of the tracers becomes suppressed upon increasing the density of the systems. These phenomena are attributed to an underlying percolation transition. In the soft potential model the transition is rounded, since each tracer encounters its own critical density according to its energy. Therefore, the rounding of the transition is a generic occurrence in realistic, soft systems.
Phase transition in linear sigma model and disoriented chiral condensate
A. K. Chaudhuri
2000-07-28T23:59:59.000Z
We have investigated the phase transition and disoriented chiral condensate domain formation in linear sigma model. Solving the equation of motion for the sigma model fields in contact with a heat bath, we have shown that the fields undergo phase transition above a certain critical temperature(T_c). It was also shown that when the fields thermalised at temperature above T_c are cooled down sufficiently rapidly, disoriented chiral condensate domains are formed quite late in the evolution.
Modeling Temporal Behavior in Large Networks: A Dynamic Mixed-Membership Model
Rossi, R; Gallagher, B; Neville, J; Henderson, K
2011-11-11T23:59:59.000Z
Given a large time-evolving network, how can we model and characterize the temporal behaviors of individual nodes (and network states)? How can we model the behavioral transition patterns of nodes? We propose a temporal behavior model that captures the 'roles' of nodes in the graph and how they evolve over time. The proposed dynamic behavioral mixed-membership model (DBMM) is scalable, fully automatic (no user-defined parameters), non-parametric/data-driven (no specific functional form or parameterization), interpretable (identifies explainable patterns), and flexible (applicable to dynamic and streaming networks). Moreover, the interpretable behavioral roles are generalizable, computationally efficient, and natively supports attributes. We applied our model for (a) identifying patterns and trends of nodes and network states based on the temporal behavior, (b) predicting future structural changes, and (c) detecting unusual temporal behavior transitions. We use eight large real-world datasets from different time-evolving settings (dynamic and streaming). In particular, we model the evolving mixed-memberships and the corresponding behavioral transitions of Twitter, Facebook, IP-Traces, Email (University), Internet AS, Enron, Reality, and IMDB. The experiments demonstrate the scalability, flexibility, and effectiveness of our model for identifying interesting patterns, detecting unusual structural transitions, and predicting the future structural changes of the network and individual nodes.
Martinello, M; Checchin, M; Grassellino, A; Crawford, A C; Melnychuk, A; Sergatskov, D A
2015-01-01T23:59:59.000Z
Cool-down dynamics of superconducting accelerating cavities became particularly important for obtaining very high quality factors in SRF cavities. Previous studies proved that when cavity is cooled fast, the quality factor is higher than when cavity is cooled slowly. This has been discovered to derive from the fact that a fast cool-down allows better magnetic field expulsion during the superconducting transition. In this paper we describe the first experiment where the temperature all around the cavity was mapped during the cavity cool-down through transition temperature, proving the existence of two different transition dynamics: a sharp superconducting-normal conducting transition during fast cool-down which favors flux expulsion and nucleation phase transition during slow cool-down, which leads to full flux trapping.
A Relativistic Dynamical Collapse Model
Philip Pearle
2014-12-21T23:59:59.000Z
A model is discussed where all operators are constructed from a quantum scalar field whose energy spectrum takes on all real values. The Schr\\"odinger picture wave function depends upon space and time coordinates for each particle, as well as an inexorably increasing evolution parameter $s$ which labels a foliation of space-like hypersurfaces. The model is constructed to be manifestly Lorentz invariant in the interaction picture. Free particle states and interactions are discussed in this framework. Then, the formalism of the CSL (Continuous Spontaneous Localization) theory of dynamical collapse is applied. The collapse-generating operator is chosen to to be the particle number space-time density. Unlike previous relativistically invariant models, the vacuum state is not excited. The collapse dynamics depends upon two parameters, a parameter $\\Lambda$ which represents the collapse rate/volume and a scale factor $\\ell$. A common example of collapse dynamics, involving a clump of matter in a superposition of two locations, is analyzed. The collapse rate is shown to be identical to that of non-relativistic CSL when the GRW-CSL choice of $\\ell=a=10^{-5}$cm, is made, along with $\\Lambda=\\lambda/a^{3}$ (GRW-CSL choice $\\lambda=10^{-16}s^{-1}$). However, it is also shown that the change of mass of a nucleon over the age of the universe is then unacceptably large. The case where $\\ell$ is the size of the universe is then considered. It is shown that the collapse behavior is satisfactory and the change of mass over the age of the universe is acceptably small, when $\\Lambda= \\lambda/\\ell a^{2}$.
Hydrogen Transition (HyTRANS) Model
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Bayesian inference of stochastic dynamical models
Lu, Peter Guang Yi
2013-01-01T23:59:59.000Z
A new methodology for Bayesian inference of stochastic dynamical models is developed. The methodology leverages the dynamically orthogonal (DO) evolution equations for reduced-dimension uncertainty evolution and the Gaussian ...
A general holographic metal/superconductor phase transition model
Yan Peng; Yunqi Liu
2014-10-27T23:59:59.000Z
We study the scalar condensation of a general holographic superconductor model in AdS black hole background away from the probe limit. We find the model parameters together with the scalar mass and backreaction can determine the order of phase transitions completely. In addition, we observe two types of discontinuities of the scalar operator in the case of first order phase transitions. We analyze in detail the effects of the scalar mass and backreaction on the formation of discontinuities and arrive at an approximate relation between the threshold model parameters. Furthermore, we obtain superconductor solutions corresponding to higher energy states and examine the stability of these superconductor solutions.
A general holographic metal/superconductor phase transition model
Yan Peng; Yunqi Liu
2015-03-03T23:59:59.000Z
We study the scalar condensation of a general holographic superconductor model in AdS black hole background away from the probe limit. We find the model parameters together with the scalar mass and backreaction can determine the order of phase transitions completely. In addition, we observe two types of discontinuities of the scalar operator in the case of first order phase transitions. We analyze in detail the effects of the scalar mass and backreaction on the formation of discontinuities and arrive at an approximate relation between the threshold model parameters. Furthermore, we obtain superconductor solutions corresponding to higher energy states and examine the stability of these superconductor solutions.
Early Warning Signals for Critical Transitions: A Generalized Modeling Approach
for early warning signals that integrates multiple sources of information and data about the system throughEarly Warning Signals for Critical Transitions: A Generalized Modeling Approach Steven J. Lade a previously published fisheries model. We regard our method as complementary to existing early warning signals
Quantum Plasma Model with Hydrodynamical Phase Transition
Introduction The quantum Jellium model is a system of electrons, interacting via Coulomb forces both with one of Fourier's law of heat conduction for a certain model of interacting atoms, the passage from quantum. The object of the present article is to provide a further quantum mechanical treatment of * Partially
Modelling and Dynamic Simulation for Process Control
Skogestad, Sigurd
principles for model development are outlined, and these principles are applied to a simple ash tank (which. In this paper we consider dynamic process models obtained using fundamental principles (eg. based reactor, a simple trend analysis using temperature measurements may be sucient. Dynamic models
Quantitative Modeling of High Temperature Magnetization Dynamics
Zhang, Shufeng
2009-03-01T23:59:59.000Z
Final Technical Report Project title: Quantitative Modeling of High Temperature Magnetization Dynamics DOE/Office of Science Program Manager Contact: Dr. James Davenport
A phase transition in commuting Gaussian multi-matrix models
Ofer Aharony; Sean A. Hartnoll
2007-07-02T23:59:59.000Z
We analyze in detail a second order phase transition that occurs in large N Gaussian multi-matrix models in which the matrices are constrained to be commuting. The phase transition occurs as the relative masses of the matrices are varied, assuming that there are at least four matrices in the lowest mass level. We also discuss the phase structure of weakly coupled large N 3+1 dimensional gauge theories compactified on a three-sphere of radius R. We argue that these theories are well described at high temperatures (T >> 1/R) by a Gaussian multi-matrix model, and that they do not exhibit any phase transitions between the deconfinement scale (T ~ 1/R) and the scale where perturbation theory breaks down (T ~ 1 / \\lambda R, where \\lambda is the 't Hooft coupling).
Conceptual aircraft dynamics from inverse aircraft modeling
Ziegler, Gregory E
1999-01-01T23:59:59.000Z
This thesis presents a method of construe' ting a nonlinear dynamics model of a theoretical aircraft from the nonlinear batch simulation of an existing aircrew This method provides control law designers with a method of fabricating nonlinear models...
Risk Modelling the Transition of SCADA System to IPv6
Boyer, Edmond
Risk Modelling the Transition of SCADA System to IPv6 Suriadi Suriadi, Alan Tickle, Ejaz Ahmed.morarji@qut.edu.au Abstract. SCADA is one of a set of manufacturing-and-control systems that are used to monitor and control6 protocol and inevitably this change will affect SCADA systems. However IPv6 introduces its own set
Zero-Safe Nets: Modeling Transactions via Transition Synchronization
Bruni, Roberto
Zero-Safe Nets: Modeling Transactions via Transition Synchronization Roberto Bruni and Ugo of the same zero-safe net. Zero-safe nets (ZS nets) have been introduced in [BM97] to provide a basic called stable places), ZS nets include a set of zero places. These are idealized resources that remain in
Model Validation with Hybrid Dynamic Simulation
Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.
2006-06-18T23:59:59.000Z
AbstractModel validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation.
Maruyama, Shigeo
Effect of flow rate of ethanol on growth dynamics of VA-SWNT - Transition from no-flow CVD a growth model [2]. In this study, the flow rate of ethanol during the CVD was controlled precisely. Figure 1 shows the growth curve of VA-SWNT film for various ethanol flow rates. In the figure, "No
Benchmarking of Planning Models Using Recorded Dynamics
Huang, Zhenyu; Yang, Bo; Kosterev, Dmitry
2009-03-15T23:59:59.000Z
Power system planning extensively uses model simulation to understand the dynamic behaviors and determine the operating limits of a power system. Model quality is key to the safety and reliability of electricity delivery. Planning model benchmarking, or model validation, has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent dynamic behavior of power system components, it has been essential to validate models against actual measurements. The development of phasor technology provides such measurements and represents a new opportunity for model validation as phasor measurements can capture power system dynamics with high-speed, time-synchronized data. Previously, methods for rigorous comparison of model simulation and recorded dynamics have been developed and applied to quantify model quality of power plants in the Western Electricity Coordinating Council (WECC). These methods can locate model components which need improvement. Recent work continues this effort and focuses on how model parameters may be calibrated to match recorded dynamics after the problematic model components are identified. A calibration method using Extended Kalman Filter technique is being developed. This paper provides an overview of prior work on model validation and presents new development on the calibration method and initial results of model parameter calibration.
Phase Transition of Laminated Models at Any Temperature
Eugene Pechersky; Elena Petrova; Sergey Pirogov
2010-02-18T23:59:59.000Z
The standard Pirogov -- Sinai theory is generalized to the class of models with two modes of interaction: longitudinal and transversal. Under rather general assumptions about the longitudinal interaction and for one specific form of the transversal interaction it is proved that such system has a variety of phase transitions at any temperature: the parameter which plays the role of inverse temperature is the strength of the transversal interaction. The concrete examples of such systems are $(1+1)$-dimensional models.
Glass transition and alpha-relaxation dynamics of thin films of labeled polystyrene
Rodney D. Priestley; Linda J. Broadbelt; John M. Torkelson; Koji Fukao
2008-01-05T23:59:59.000Z
The glass transition temperature and relaxation dynamics of the segmental motions of thin films of polystyrene labeled with a dye, 4-[N-ethyl-N-(hydroxyethyl)]amino-4-nitraozobenzene (Disperse Red 1, DR1) are investigated using dielectric measurements. The dielectric relaxation strength of the DR1-labeled polystyrene is approximately 65 times larger than that of the unlabeled polystyrene above the glass transition, while there is almost no difference between them below the glass transition. The glass transition temperature of the DR1-labeled polystyrene can be determined as a crossover temperature at which the temperature coefficient of the electric capacitance changes from the value of the glassy state to that of the liquid state. The glass transition temperature of the DR1-labeled polystyrene decreases with decreasing film thickness in a reasonably similar manner to that of the unlabeled polystyrene thin films. The dielectric relaxation spectrum of the DR1-labeled polystyrene is also investigated. As thickness decreases, the $\\alpha$-relaxation time becomes smaller and the distribution of the $\\alpha$-relaxation times becomes broader. These results show that thin films of DR1-labeled polystyrene are a suitable system for investigating confinement effects of the glass transition dynamics using dielectric relaxation spectroscopy.
Molecular dynamics simulation of the plastic to triclinic phase transition in clusters of SF6
Paris-Sud XI, Universit de
41 Molecular dynamics simulation of the plastic to triclinic phase transition in clusters of SF6 A agrgats n'a pas t entreprise. Abstract. 2014 Clusters of 512 SF6 molecules in their condensed phases of finite systems such as clusters [2]. Liquid sulphur hexafluoride, SF6, forms on cooling what is known
Heavy-quark potential with dynamical flavors: A first-order transition
Bigazzi, Francesco [Physique Theorique et Mathematique and International Solvay Institutes, Universite Libre de Bruxelles, CP 231, B-1050 Bruxelles (Belgium); Cotrone, Aldo L. [Institute for Theoretical Physics, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Nunez, Carlos [University of Wales Swansea, Department of Physics, Singleton Park, Swansea, SA2 8PP, Wales (United Kingdom); Paredes, Angel [Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht (Netherlands)
2008-12-01T23:59:59.000Z
We study the static potential between external quark-antiquark pairs in a strongly coupled gauge theory with a large number of colors and massive dynamical flavors, using a dual string description. When the constituent mass of the dynamical quarks is set below a certain critical value, we find a first-order phase transition between a linear and a Coulomb-like regime. Above the critical mass the two phases are smoothly connected. We also study the dependence on the theory parameters of the quark-antiquark separation at which the static configuration decays into specific static-dynamical mesons.
A Markov model of land use dynamics
Campillo, Fabien; Raherinirina, Angelo; Rakotozafy, Rivo
2011-01-01T23:59:59.000Z
The application of the Markov chain to modeling agricultural succession is well known. In most cases, the main problem is the inference of the model, i.e. the estimation of the transition matrix. In this work we present methods to estimate the transition matrix from historical observations. In addition to the estimator of maximum likelihood (MLE), we also consider the Bayes estimator associated with the Jeffreys prior. This Bayes estimator will be approximated by a Markov chain Monte Carlo (MCMC) method. We also propose a method based on the sojourn time to test the adequation of Markov chain model to the dataset.
Structure and dynamics of colloidal depletion gels: coincidence of transitions and heterogeneity
C. J. Dibble; M. Kogan; M. J. Solomon
2006-06-06T23:59:59.000Z
Transitions in structural heterogeneity of colloidal depletion gels formed through short-range attractive interactions are correlated with their dynamical arrest. The system is a density and refractive index matched suspension of 0.20 volume fraction poly(methyl methacyrlate) colloids with the non-adsorbing depletant polystyrene added at a size ratio of depletant to colloid of 0.043. As the strength of the short-range attractive interaction is increased, clusters become increasingly structurally heterogeneous, as characterized by number-density fluctuations, and dynamically immobilized, as characterized by the single-particle mean-squared displacement. The number of free colloids in the suspension also progressively declines. As an immobile cluster to gel transition is traversed, structural heterogeneity abruptly decreases. Simultaneously, the mean single-particle dynamics saturates at a localization length on the order of the short-range attractive potential range. Both immobile cluster and gel regimes show dynamical heterogeneity. Non-Gaussian distributions of single particle displacements reveal enhanced populations of dynamical trajectories localized on two different length scales. Similar dependencies of number density fluctuations, free particle number and dynamical length scales on the order of the range of short-range attraction suggests a collective structural origin of dynamic heterogeneity in colloidal gels.
Very Large System Dynamics Models - Lessons Learned
Jacob J. Jacobson; Leonard Malczynski
2008-10-01T23:59:59.000Z
This paper provides lessons learned from developing several large system dynamics (SD) models. System dynamics modeling practice emphasize the need to keep models small so that they are manageable and understandable. This practice is generally reasonable and prudent; however, there are times that large SD models are necessary. This paper outlines two large SD projects that were done at two Department of Energy National Laboratories, the Idaho National Laboratory and Sandia National Laboratories. This paper summarizes the models and then discusses some of the valuable lessons learned during these two modeling efforts.
OPTIMAL CONTROL WITH ADAPTIVE INTERNAL DYNAMICS MODELS
Vijayakumar, Sethu
. The optimal feedback control law for systems with non-linear dynamics and non-quadratic costs can be foundOPTIMAL CONTROL WITH ADAPTIVE INTERNAL DYNAMICS MODELS Djordje Mitrovic, Stefan Klanke, and Sethu, optimal control, adaptive control, robot simulation Abstract: Optimal feedback control has been proposed
Baird, Matthew David
2012-01-01T23:59:59.000Z
additively non-separable linear regression model. First,the additively non-separable linear regression model matchesThe additively non-separable linear regression model nests
Simple Dynamic Gasifier Model That Runs in Aspen Dynamics
Robinson, P.J.; Luyben, W.L. [Lehigh University, Bethlehem, PA (United States). Dept. of Chemical Engineering
2008-10-15T23:59:59.000Z
Gasification (or partial oxidation) is a vital component of 'clean coal' technology. Sulfur and nitrogen emissions can be reduced, overall energy efficiency is increased, and carbon dioxide recovery and sequestration are facilitated. Gasification units in an electric power generation plant produce a fuel for driving combustion turbines. Gasification units in a chemical plant generate gas, which can be used to produce a wide spectrum of chemical products. Future plants are predicted to be hybrid power/chemical plants with gasification as the key unit operation. The widely used process simulator Aspen Plus provides a library of models that can be used to develop an overall gasifier model that handles solids. So steady-state design and optimization studies of processes with gasifiers can be undertaken. This paper presents a simple approximate method for achieving the objective of having a gasifier model that can be exported into Aspen Dynamics. The basic idea is to use a high molecular weight hydrocarbon that is present in the Aspen library as a pseudofuel. This component should have the same 1:1 hydrogen-to-carbon ratio that is found in coal and biomass. For many plantwide dynamic studies, a rigorous high-fidelity dynamic model of the gasifier is not needed because its dynamics are very fast and the gasifier gas volume is a relatively small fraction of the total volume of the entire plant. The proposed approximate model captures the essential macroscale thermal, flow, composition, and pressure dynamics. This paper does not attempt to optimize the design or control of gasifiers but merely presents an idea of how to dynamically simulate coal gasification in an approximate way.
Can xenon in water inhibit ice growth? Molecular dynamics of phase transitions in water$-$Xe system
Vasilii I. Artyukhov; Alexander Yu. Pulver; Alex Peregudov; Igor Artyuhov
2014-07-11T23:59:59.000Z
Motivated by recent experiments showing the promise of noble gases as cryoprotectants, we perform molecular dynamics modeling of phase transitions in water with xenon under cooling. We study the structure and dynamics of xenon water solution as a function of temperature. Homogeneous nucleation of clathrate hydrate phase is observed and characterized. As the temperature is further reduced we observe hints of dissociation of clathrate due to stronger hydrophobic hydration, pointing towards a possible instability of clathrate at cryogenic temperatures and conversion to an amorphous phase comprised of "xenon + hydration shell" Xe$\\cdot$(H$_{2}$O)$_{21.5}$ clusters. Simulations of ice$-$xenon solution interface in equilibrium and during ice growth reveal the effects of xenon on the ice$-$liquid interface, where adsorbed xenon causes roughening of ice surface but does not preferentially form clathrate. These results provide evidence against the ice-blocker mechanism of xenon cryoprotection.
Rodriguez-Vega, M; Radue, E; Kittiwatanakul, S; Lu, J; Wolf, S A; Lukaszew, R A; Novikova, I; Rossi, E
2015-01-01T23:59:59.000Z
We study the thermal relaxation dynamics of VO$_2$ films after the ultrafast photo-induced metal-insulator transition for two VO$_2$ film samples grown on Al$_2$O$_3$ and TiO$_2$ substrates. We find two orders of magnitude difference in the recovery time (a few ns for the VO$_2$/Al$_2$O$_3$ sample vs. hundreds of ns for the VO$_2$/TiO$_2$ sample). We present a theoretical model that accurately describes the MIT thermal properties and interpret the experimental measurements. We obtain quantitative results that show how the microstructure of the VO$_2$ film and the thermal conductivity of the interface between the VO$_2$ film and the substrate affect long time-scale recovery dynamics. We also obtain a simple analytic relationship between the recovery time-scale and some of the film parameters.
Dynamics of skyrmions in chiral magnets: Dynamic phase transitions and equation of motion
Lin, Shi-Zeng, E-mail: szl@lanl.gov; Reichhardt, Charles; Batista, Cristian D.; Saxena, Avadh [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-05-07T23:59:59.000Z
We study the dynamics of skyrmions in a metallic chiral magnet. First, we show that skyrmions can be created dynamically by destabilizing the ferromagnetic background state through a spin polarized current. We then treat skyrmions as rigid particles and derive the corresponding equation of motion. The dynamics of skyrmions is dominated by the Magnus force, which accounts for the weak pinning of skyrmions observed in experiments. Finally, we discuss the quantum motion of skyrmions.
A holographic model for antiferromagnetic quantum phase transition induced by magnetic field
Rong-Gen Cai; Run-Qiu Yang; F. V. Kusmartsev
2015-01-19T23:59:59.000Z
We propose a gravity dual of antiferromagnetic quantum phase transition (QPT) induced by magnetic field and study the criticality in the vicinity of quantum critical point (QCP). Results show the boundary critical theory is a strong coupling theory with dynamic exponent $z=2$. The hyperscaling law is violated and logarithmic corrections appear near the QCP. We compare our theoretical results with experimental data on variety of materials including low-dimensional magnet, BiCoPO$_5$ and pyrochlores, Er$_{2-2x}$Y$_{2x}$Ti$_2$O$_7$. Our model describes well the existing experiments and predicts QCP and other high field magnetic properties of these compounds.
A holographic model for antiferromagnetic quantum phase transition induced by magnetic field
Cai, Rong-Gen; Kusmartsev, F V
2015-01-01T23:59:59.000Z
We propose a gravity dual of antiferromagnetic quantum phase transition (QPT) induced by magnetic field and study the criticality in the vicinity of quantum critical point (QCP). Results show the boundary critical theory is a strong coupling theory with dynamic exponent $z=2$. The hyperscaling law is violated and logarithmic corrections appear near the QCP. We compare our theoretical results with experimental data on variety of materials including low-dimensional magnet, BiCoPO$_5$ and pyrochlores, Er$_{2-2x}$Y$_{2x}$Ti$_2$O$_7$. Our model describes well the existing experiments and predicts QCP and other high field magnetic properties of these compounds.
Stochastic ratcheting of two dimensional colloids : Directed current and dynamical transitions
Dipanjan Chakraborty; Debasish Chaudhuri
2014-07-09T23:59:59.000Z
We present results of molecular dynamics simulations for two-dimensional repulsively interacting colloids driven by an one dimensional asymmetric and commensurate ratchet potential, switching on and off stochastically. The resultant time- and space-averaged directed current exhibits resonance with change in ratcheting frequency. The resonance frequency itself varies non-monotonically with density. We use scaling arguments to derive analytic expression for the directed current which reproduces these features. Our simulations reveal re-entrant dynamical transitions between solid and modulated liquid phases as a function of ratcheting frequency, associated with the variation of directed current.
K. Grzybowska; A. Grzybowski; S. Pawlus; J. Pionteck; M. Paluch
2014-10-23T23:59:59.000Z
In this Letter, we investigate how changes in the system entropy influence the characteristic time scale of the system molecular dynamics near the glass transition. Independently of any model of thermodynamic evolution of the time scale, against some previous suppositions, we show that the system entropy $S$ is not sufficient to govern the time scale defined by structural relaxation time $\\tau $. In the density scaling regime, we argue that the decoupling between $\\tau $ and $S$ is a consequence of different values of the scaling exponents $\\gamma $ and $\\gamma_S $ in the density scaling laws, $\\tau = f(\\rho ^\\gamma /T)$ and $S = h(\\rho ^{\\gamma_S}/T)$, where $\\rho $ and $T$ denote density and temperature, respectively. It implies that the proper relation between $\\tau $ and $S$ requires supplementing with a density factor, $u(\\rho)$, i.e.,$\\tau = g(u(\\rho)w(S))$. This meaningful finding additionally demonstrates that the density scaling idea can be successfully used to separate physically relevant contributions to the time scale of molecular dynamics near the glass transition. As an example, we revise the Avramov entropic model of the dependence $\\tau (T,\\rho)$, giving evidence that its entropic basis has to be extended by the density dependence of the maximal energy barrier for structural relaxation. We also discuss the excess entropy $S_{ex}$, the density scaling of which is found to mimic the density scaling of the total system entropy $S$.
Stochastic storage models and noise-induced phase transitions
Serge Shpyrko; V. V. Ryazanov
2007-01-13T23:59:59.000Z
The most frequently used in physical application diffusive (based on the Fokker-Planck equation) model leans upon the assumption of small jumps of a macroscopic variable for each given realization of the stochastic process. This imposes restrictions on the description of the phase transition problem where the system is to overcome some finite potential barrier, or systems with finite size where the fluctuations are comparable with the size of a system. We suggest a complementary stochastic description of physical systems based on the mathematical stochastic storage model with basic notions of random input and output into a system. It reproduces statistical distributions typical for noise-induced phase transitions (e.g. Verhulst model) for the simplest (up to linear) forms of the escape function. We consider a generalization of the stochastic model based on the series development of the kinetic potential. On the contrast to Gaussian processes in which the development in series over a small parameter characterizing the jump value is assumed [Stratonovich R.L., Nonlinear Nonequilibrium Thermodynamics, Springer Series in Synergetics, vol.59, Springer Verlag, 1994], we propose a series expansion directly suitable for storage models and introduce the kinetic potential generalizing them.
Model Validation with Hybrid Dynamic Simulation
Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.
2006-06-22T23:59:59.000Z
AbstractModel validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation. A few methods to define model quality indices have been proposed to quantify model error for model validation criteria development.
Some results on the dynamics and transition probabilities for non self-adjoint hamiltonians
Fabio Bagarello
2015-02-25T23:59:59.000Z
We discuss systematically several possible inequivalent ways to describe the dynamics and the transition probabilities of a quantum system when its hamiltonian is not self-adjoint. In order to simplify the treatment, we mainly restrict our analysis to finite dimensional Hilbert spaces. In particular, we propose some experiments which could discriminate between the various possibilities considered in the paper. An example taken from the literature is discussed in detail.
Dynamical models with a general anisotropy profile
M. Baes; E. Van Hese
2007-05-28T23:59:59.000Z
Both numerical simulations and observational evidence indicate that the outer regions of galaxies and dark matter haloes are typically mildly to significantly radially anisotropic. The inner regions can be significantly non-isotropic, depending on the dynamical formation and evolution processes. In an attempt to break the lack of simple dynamical models that can reproduce this behaviour, we explore a technique to construct dynamical models with an arbitrary density and an arbitrary anisotropy profile. We outline a general construction method and propose a more practical approach based on a parameterized anisotropy profile. This approach consists of fitting the density of the model with a set of dynamical components, each of which have the same anisotropy profile. Using this approach we avoid the delicate fine-tuning difficulties other fitting techniques typically encounter when constructing radially anisotropic models. We present a model anisotropy profile that generalizes the Osipkov-Merritt profile, and that can represent any smooth monotonic anisotropy profile. Based on this model anisotropy profile, we construct a very general seven-parameter set of dynamical components for which the most important dynamical properties can be calculated analytically. We use the results to look for simple one-component dynamical models that generate simple potential-density pairs while still supporting a flexible anisotropy profile. We present families of Plummer and Hernquist models in which the anisotropy at small and large radii can be chosen as free parameters. We also generalize these two families to a three-parameter family that self-consistently generates the set of Veltmann potential-density pairs. (Abridged...)
Razzak, M. Abdur; Takamura, Shuichi; Uesugi, Yoshihiko [Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Department of Electrical and Electronic Engineering, Kanazawa University 2-40-20 Kodatsuno, Ishikawa 920-8667 (Japan)
2004-11-01T23:59:59.000Z
The influences of rf driving power, neutral gas pressure, and nitrogen seeding on the electrostatic-to-electromagnetic (E-H) mode transition dynamics in radio-frequency argon inductively coupled plasmas (ICPs) in a pressure range of 50-100 kPa are investigated, both experimentally and theoretically. The E-H mode transition dynamics and its characteristic transition time scale are investigated by observing the high-speed imaging (13 500 fps) as well as the temporal change of plasma loading impedance. The experimental results reveal that the E-H mode transition time is not fixed at any operating conditions rather it depends on some important parameters such as the rf driving power, neutral gas pressure, gas type. It is found that the E-H mode transition time depends on the unique parameter E{sub {theta}}/p; the so-called effective induced electric field, rather than the independent parameter: the rf power or neutral gas pressure. It is also found that longer E-H mode transition time is required to ignite the high-pressure Ar-N{sub 2} plasmas with a 2.5%-10% N{sub 2} seeding than that of pure Ar plasmas with the same operating conditions. The experimental results are compared with that of the recently developed theoretical models, and a good agreement is found between them.
Consistent nonlinear dynamics: identifying model inadequacy
Patrick E. McSharry; Leonard A. Smith
2004-03-09T23:59:59.000Z
Empirical modelling often aims for the simplest model consistent with the data. A new technique is presented which quantifies the consistency of the model dynamics as a function of location in state space. As is well-known, traditional statistics of nonlinear models like root-mean-square (RMS) forecast error can prove misleading. Testing consistency is shown to overcome some of the deficiencies of RMS error, both within the perfect model scenario and when applied to data from several physical systems using previously published models. In particular, testing for consistent nonlinear dynamics provides insight towards (i) identifying when a delay reconstruction fails to be an embedding, (ii) allowing state dependent model selection and (iii) optimising local neighbourhood size. It also provides a more relevant (state dependent) threshold for identifying false nearest neighbours.
Dynamic Modeling of Butterfly Subdivision Surfaces
Qin, Hong
on control vertices. This provides the user an intuitive and natural feeling that is produced while modeling manipulation of control points, whereas we provide interaction tools that directly manipulate the smooth limitDynamic Modeling of Butterfly Subdivision Surfaces Chhandomay Mandal, Hong Qin, Member, IEEE
Modeling dynamic swarms q Bernard Ghanem a,
Ahuja, Narendra
a c t This paper proposes the problem of modeling video sequences of dynamic swarms (DSs). We define of our method by conducting experiments on real and synthetic video sequences. Real sequences of birds Elsevier Inc. All rights reserved. 1. Introduction This paper is about modeling video sequences of a dense
Phase transitions in a reaction-diffusion model on a line with boundaries
Khorrami, Mohammad, E-mail: mamwad@mailaps.org; Aghamohammadi, Amir, E-mail: mohamadi@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of)] [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of)
2014-03-15T23:59:59.000Z
A one-dimensional model on a line of length L is investigated, which involves particle diffusion as well as single particle annihilation. There are also creation and annihilation at the boundaries. The static and dynamical behaviors of the system are studied. It is seen that the system could exhibit a dynamical phase transition. For small drift velocities, the relaxation time does not depend on the absorption rates at the boundaries. This is the fast phase. For large velocities, the smaller of the absorption rates at boundaries enter the relaxation rate and makes it longer. This is the slow phase. Finally, the effect of a random particle creation in the bulk is also investigated.
A stochastic model dissects cell states in biological transition processes
Armond, Jonathan W.
Many biological processes, including differentiation, reprogramming, and disease transformations, involve transitions of cells through distinct states. Direct, unbiased investigation of cell states and their transitions ...
Hysteretic transitions in the Kuramoto model with inertia
Simona Olmi; Adrian Navas; Stefano Boccaletti; Alessandro Torcini
2014-08-11T23:59:59.000Z
We report finite size numerical investigations and mean field analysis of a Kuramoto model with inertia for fully coupled and diluted systems. In particular, we examine for a Gaussian distribution of the frequencies the transition from incoherence to coherence for increasingly large system size and inertia. For sufficiently large inertia the transition is hysteretic and within the hysteretic region clusters of locked oscillators of various sizes and different levels of synchronization coexist. A modification of the mean field theory developed by Tanaka, Lichtenberg, and Oishi [Physica D, 100 (1997) 279] allows to derive the synchronization profile associated to each of these clusters. We have also investigated numerically the limits of existence of the coherent and of the incoherent solutions. The minimal coupling required to observe the coherent state is largely independent of the system size and it saturates to a constant value already for moderately large inertia values. The incoherent state is observable up to a critical coupling whose value saturates for large inertia and for finite system sizes, while in the thermodinamic limit this critical value diverges proportionally to the mass. By increasing the inertia the transition becomes more complex, and the synchronization occurs via the emergence of clusters of whirling oscillators. The presence of these groups of coherently drifting oscillators induces oscillations in the order parameter. We have shown that the transition remains hysteretic even for randomly diluted networks up to a level of connectivity corresponding to few links per oscillator. Finally, an application to the Italian high-voltage power grid is reported, which reveals the emergence of quasi-periodic oscillations in the order parameter due to the simultaneous presence of many competing whirling clusters.
A numerical study of longtime dynamics and ergodic-nonergodic transitions in dense simple fluids
David D. McCowan
2014-11-04T23:59:59.000Z
For over 30 years, mode-coupling theory (MCT) has been the de facto theoretic description of dense fluids and the liquid-glass transition. MCT, however, is limited by its ad hoc construction and lacks a mechanism to institute corrections. We use recent results from a new theoretical framework--developed from first principles via a self-consistent perturbation expansion in terms of an effective two-body potential--to numerically explore the kinetics of systems of classical particles, specifically hard spheres obeying Smoluchowski dynamics. We present here a full solution to the kinetic equation governing the density-density time correlation function and show that the function exhibits the characteristic two-step decay of supercooled fluids and an ergodic-nonergodic transition to a dynamically-arrested state. Unlike many previous numerical studies and experiments, we have access to the full time and wavenumber range of the correlation function and can track the solution unprecedentedly close to the transition, covering nearly 15 decades of time. Using asymptotic approximation techniques developed for MCT, we fit the solution to predicted forms and extract critical parameters. Our solution shows a transition at packing fraction $\\eta^*=0.60149761(10)$--consistent with previous static solutions under this theory and with comparable colloidal suspension experiments--and the behavior in the $\\beta$-relaxation regime is fit to power-law decays with critical exponents $a=0.375(3)$ and $b=0.8887(4)$, and with $\\lambda=0.5587(18)$. For the $\\alpha$-relaxation of the ergodic phase, we find a power-law divergence of the time scale $\\tau_{\\alpha}$ as we approach the transition. Through these results, we establish that this new theory is able to reproduce the salient features of MCT, but has the advantages of a first principles derivation and a clear mechanism for making systematic improvements.
Modeling the Dynamics of Compromised Networks
Soper, B; Merl, D M
2011-09-12T23:59:59.000Z
Accurate predictive models of compromised networks would contribute greatly to improving the effectiveness and efficiency of the detection and control of network attacks. Compartmental epidemiological models have been applied to modeling attack vectors such as viruses and worms. We extend the application of these models to capture a wider class of dynamics applicable to cyber security. By making basic assumptions regarding network topology we use multi-group epidemiological models and reaction rate kinetics to model the stochastic evolution of a compromised network. The Gillespie Algorithm is used to run simulations under a worst case scenario in which the intruder follows the basic connection rates of network traffic as a method of obfuscation.
Huse, Nils; Kim, Tae Kyu; Khalil, Munira; Jamula, Lindsey; McCusker, James K.; Schoenlein, Robert W.
2010-05-02T23:59:59.000Z
We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding.
Texas at Austin. University of
in Lennard-Jonesium and Tin J. M. D. Lane #3; and M. P. Marder y Center for Nonlinear Dynamics, University for shocks in tin which agrees to within 6% with experimental data. We study the strong shock to elastic-plastic shock transition in tin and #12;nd that it is a continuous transition consistent with a transcritical
de Gispert, Adri
A molecular dynamics simulation of the melting points and glass transition temperatures of myo transition temperature are calculated for myo- and neo-inositol, using the condensed-phase optimized temperatures for myo- and neo-inositol also compare very well to the experimentally obtained data. The glass
Model for Aggregated Water Heater Load Using Dynamic Bayesian Networks
Vlachopoulou, Maria; Chin, George; Fuller, Jason C.; Lu, Shuai; Kalsi, Karanjit
2012-07-19T23:59:59.000Z
The transition to the new generation power grid, or smart grid, requires novel ways of using and analyzing data collected from the grid infrastructure. Fundamental functionalities like demand response (DR), that the smart grid needs, rely heavily on the ability of the energy providers and distributors to forecast the load behavior of appliances under different DR strategies. This paper presents a new model of aggregated water heater load, based on dynamic Bayesian networks (DBNs). The model has been validated against simulated data from an open source distribution simulation software (GridLAB-D). The results presented in this paper demonstrate that the DBN model accurately tracks the load profile curves of aggregated water heaters under different testing scenarios.
Dynamical System Analysis for a phantom model
Nilanjana Mahata; Subenoy Chakraborty
2014-04-24T23:59:59.000Z
The paper deals with a dynamical system analysis related to phantom cosmological model . Here gravity is coupled to phantom scalar field having scalar coupling function and a potential. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables and assuming some suitable form of the potential function. Finally, critical points are evaluated, their nature have been analyzed and corresponding cosmological scenario has been discussed.
Dynamical dark matter. II. An explicit model
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Dienes, Keith R.; Thomas, Brooks
2012-04-01T23:59:59.000Z
In a recent paper [K. R. Dienes and B. Thomas, Phys. Rev. D 85, 083523 (2012).], we introduced dynamical dark matter, a new framework for dark-matter physics, and outlined its underlying theoretical principles and phenomenological possibilities. Unlike most traditional approaches to the dark-matter problem which hypothesize the existence of one or more stable dark-matter particles, our dynamical dark-matter framework is characterized by the fact that the requirement of stability is replaced by a delicate balancing between cosmological abundances and lifetimes across a vast ensemble of individual dark-matter components. This setup therefore collectively produces a time-varying cosmological dark-matter abundance, and the different dark-matter components can interact and decay throughout the current epoch. While the goal of our previous paper was to introduce the broad theoretical aspects of this framework, the purpose of the current paper is to provide an explicit model of dynamical dark matter and demonstrate that this model satisfies all collider, astrophysical, and cosmological constraints. The results of this paper therefore constitute an existence proof of the phenomenological viability of our overall dynamical dark-matter framework, and demonstrate that dynamical dark matter is indeed a viable alternative to the traditional paradigm of dark-matter physics. Dynamical dark matter must therefore be considered alongside other approaches to the dark-matter problem, particularly in scenarios involving large extra dimensions or string theory in which there exist large numbers of particles which are neutral under standard-model symmetries.
Geramifard, Alborz
Solving large scale sequential decision making problems without prior knowledge of the state transition model is a key problem in the planning literature. One approach to tackle this problem is to learn the state transition ...
Lattice spacing dependence of phase transition temperature in the classical linear sigma model
A. K. Chaudhuri
2001-05-02T23:59:59.000Z
We have investigated the phase transition properties of classical linear sigma model. The fields were kept in contact with a heat bath for sufficiently long time such that fields are equilibrated at the temperature of the heat bath. It was shown that the sigma model fields undergoes phase transition, but the transition temperature depend crucially on the lattice spacing. In the continuum limit, the transition temperature tends to zero or at least to a very low value.
Development and validation of a transition model based on a mechanical approximation
Vizinho, R; Silvestre, M
2015-01-01T23:59:59.000Z
A new 3D transition turbulence model, more accurate and faster than an empirical transition model, is proposed. The model is based on the calculation of the pre-transitional u'v' due to mean flow shear. The present transition model is fully described and verified against eight benchmark test cases. Computations are performed for the ERCOFTAC flat-plate T3A, T3C and T3L test cases. Further, the model is validated for bypass, cross-flow and separation induced transition and compared with empirical transition models. The model presents very good results for bypass transition under zero-pressure gradient and with pressure gradient flow conditions. Also the model is able to correctly predict separation induced transition. However, for very low speed and low free-stream turbulence intensity the model delays separation induced transition onset. The model also shows very good results for transition under complex cross-flow conditions in three-dimensional geometries. The 3D tested case was the 6:1 prolate-spheroid und...
Absorbing Phase Transitions and Dynamic Freezing in Running Active Matter Systems
C. Reichhardt; C. J. Olson Reichhardt
2014-06-12T23:59:59.000Z
We examine a two-dimensional system of sterically repulsive interacting disks where each particle runs in a random direction. This system is equivalent to a run-and-tumble dynamics system in the limit where the run time is infinite. At low densities, we find a strongly fluctuating state composed of transient clusters. Above a critical density that is well below the density at which non-active particles would crystallize, the system can organize into a drifting quiescent or frozen state where the fluctuations are lost and large crystallites form surrounded by a small density of individual particles. Although all the particles are still moving, their paths form closed orbits. The average transient time to organize into the quiescent state diverges as a power law upon approaching the critical density from above. We compare our results to the random organization observed for periodically sheared systems that can undergo an absorbing transition from a fluctuating state to a dynamical non-fluctuating state. In the random organization studies, the system organizes to a state in which the particles no longer interact; in contrast, we find that the randomly running active matter organizes to a strongly interacting dynamically jammed state. We show that the transition to the frozen state is robust against a certain range of stochastic fluctuations. We also examine the effects of adding a small number of pinned particles to the system and find that the transition to the frozen state shifts to significantly lower densities and arises via the nucleation of faceted crystals centered at the obstacles.
Paul Glendinning; Piotr Kowalczyk
2009-01-20T23:59:59.000Z
We demonstrate on a representative example of a planar hybrid system with digital sampling a sudden transition from a stable limit cycle to the onset of chaotic dynamics. We show that the scaling law in the size of the attractor is proportional to the digital sampling time $\\tau$ for sufficiently small values of $\\tau.$ Numerical and analytical results are given. The scaling law changes to a nonlinear law for large values of the sampling time $\\tau.$ This phenomenon is explained by the change in the boundedness of the attractor.
Fern ndez-Pacheco, A.; Ummelen, F. C.; Mansell, R.; Petit, D.; Lee, J. H.; Swagten, H. J. M.; Cowburn, R. P.
2014-09-05T23:59:59.000Z
, Phys. Rev. Lett. 98, 117204, (2007). 19P. J. Metaxas, R. L. Stamps, J.-P. Jamet, J. Ferr#2;e, V. Baltz, B. Rodmacq, and P. Politi, Phys. Rev. Lett. 104, 237206 (2010). 20N. Wiese, T. Dimopoulos, M. Ruhrig, J. Wecker, and G. Reiss, J. Appl. Phys. 98... Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition A. Fernndez-Pacheco, F. C. Ummelen, R. Mansell, D. Petit, J. H. Lee, H. J. M. Swagten, and R. P. Cowburn Citation: Applied Physics...
Modeling of Reactor Kinetics and Dynamics
Matthew Johnson; Scott Lucas; Pavel Tsvetkov
2010-09-01T23:59:59.000Z
In order to model a full fuel cycle in a nuclear reactor, it is necessary to simulate the short time-scale kinetic behavior of the reactor as well as the long time-scale dynamics that occur with fuel burnup. The former is modeled using the point kinetics equations, while the latter is modeled by coupling fuel burnup equations with the kinetics equations. When the equations are solved simultaneously with a nonlinear equation solver, the end result is a code with the unique capability of modeling transients at any time during a fuel cycle.
DYNAMIC MODELING PROTON EXCHANGE MEMBRANE FUEL CELL
Mease, Kenneth D.
DYNAMIC MODELING PROTON EXCHANGE MEMBRANE FUEL CELL OVERVIEW Current/Completed Plug Power to garner SCAQMD funding for fuel cell testing GenCore system is sensitive to diluents As built design stream to compensate for removal of EGR Functionality of the modified GenCore Fuel Cell system
Modeling the Dynamics of Fermentation and Respiratory
Sheffield, University of
, denitrification, and SO4-reduction). The accumulation of acetate as a fermentation product within the plume species, e.g., H2(aq) or acetate, followed by respiration by other groups of organisms where fermentationModeling the Dynamics of Fermentation and Respiratory Processes in a Groundwater Plume of Phenolic
On connecting the dynamics of the chromosphere and transition region with Hinode SOT and EIS
Viggo H. Hansteen; Bart De Pontieu; Mats Carlsson; Scott McIntosh; Tetsuya Watanabe; Harry Warren; Louise Harra; Hirohisa Hara; Theodore D. Tarbell; Dick Shine; Alan Title; Carolus J. Schrijver; Saku Tsuneta; Yukio Katsukawa; Kiyoshi Ichimoto; Yoshinori Suematsu; Toshifumi Shimizu
2007-11-04T23:59:59.000Z
We use coordinated Hinode SOT/EIS observations that include high-resolution magnetograms, chromospheric and TR imaging and TR/coronal spectra in a first test to study how the dynamics of the TR are driven by the highly dynamic photospheric magnetic fields and the ubiquitous chromospheric waves. Initial analysis shows that these connections are quite subtle and require a combination of techniques including magnetic field extrapolations, frequency-filtered time-series and comparisons with synthetic chromospheric and TR images from advanced 3D numerical simulations. As a first result, we find signatures of magnetic flux emergence as well as 3 and 5 mHz wave power above regions of enhanced photospheric magnetic field in both chromospheric, transition region and coronal emission.
Soo-Young Lee; Sunghwan Rim; Eui-Soon Yim; C. H. Lee
1998-09-05T23:59:59.000Z
The Robnik billiard is investigated in detail both classically and quantally in the transition range from integrable to almost chaotic system. We find out that a remarkable correspondence between characteristic features of classical dynamics, especially topological structure of integrable regions in the Poincar\\'{e} surface of section, and the statistics of energy level spacings appears with a system parameter $\\lambda$ being varied. It is shown that the variance of the level spacing distribution changes its behavior at every particular values of $\\lambda$ in such a way that classical dynamics changes its topological structure in the Poincar\\'{e} surface of section, while the skewness and the excess of the level spacings seem to be closely relevant to the interface structure between integrable region and chaotic sea rather than inner structure of intergrable regoin.
Feature extraction for structural dynamics model validation
Hemez, Francois [Los Alamos National Laboratory; Farrar, Charles [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory; Nishio, Mayuko [UNIV OF TOKYO; Worden, Keith [UNIV OF SHEFFIELD; Takeda, Nobuo [UNIV OF TOKYO
2010-11-08T23:59:59.000Z
This study focuses on defining and comparing response features that can be used for structural dynamics model validation studies. Features extracted from dynamic responses obtained analytically or experimentally, such as basic signal statistics, frequency spectra, and estimated time-series models, can be used to compare characteristics of structural system dynamics. By comparing those response features extracted from experimental data and numerical outputs, validation and uncertainty quantification of numerical model containing uncertain parameters can be realized. In this study, the applicability of some response features to model validation is first discussed using measured data from a simple test-bed structure and the associated numerical simulations of these experiments. issues that must be considered were sensitivity, dimensionality, type of response, and presence or absence of measurement noise in the response. Furthermore, we illustrate a comparison method of multivariate feature vectors for statistical model validation. Results show that the outlier detection technique using the Mahalanobis distance metric can be used as an effective and quantifiable technique for selecting appropriate model parameters. However, in this process, one must not only consider the sensitivity of the features being used, but also correlation of the parameters being compared.
Nanoscopic Dynamics of Phospholipid in Unilamellar Vesicles: Effect of Gel to Fluid Phase Transition
Sharma, Veerendra K [ORNL; Mamontov, Eugene [ORNL; Anunciado, Divina B [ORNL; O'Neill, Hugh Michael [ORNL; Urban, Volker S [ORNL
2015-01-01T23:59:59.000Z
Dynamics of phospholipids in unilamellar vesicles (ULV) is of interest in biology, medical, and food sciences since these molecules are widely used as biocompatible agents and a mimic of cell membrane systems. We have investigated the nanoscopic dynamics of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipid in ULV as a function of temperature using elastic and quasielastic neutron scattering (QENS). The dependence of the signal on the scattering momentum transfer, which is a critical advantage of neutron scattering techniques, allows the detailed analysis of the lipid motions that cannot be carried out by other means. In agreement with a differential scanning calorimetry measurement, a sharp rise in the elastic scattering intensity below ca. 296 K indicates a phase transition from the high-temperature fluid phase to the low-temperature solid gel phase. The microscopic lipid dynamics exhibits qualitative differences between the solid gel phase (in a measurement at 280 K) and the fluid phase (in a measurement at a physiological temperature of 310 K). The data analysis invariably shows the presence of two distinct motions: the whole lipid molecule motion within a monolayer, or lateral diffusion, and the relatively faster internal motion of the DMPC molecule. The lateral diffusion of the whole lipid molecule is found to be Fickian in character, whereas the internal lipid motions are of localized character, consistent with the structure of the vesicles. The lateral motion slows down by an order of magnitude in the solid gel phase, whereas for the internal motion not only the time scale, but also the character of the motion changes upon the phase transition. In the solid gel phase, the lipids are more ordered and undergo uniaxial rotational motion. However, in the fluid phase, the hydrogen atoms of the lipid tails undergo confined translation diffusion rather than uniaxial rotational diffusion. The localized translational diffusion of the hydrogen atoms of the lipid tails is a manifestation of the flexibility of the chains acquired in the fluid phase. Because of this flexibility, both the local diffusivity and the confinement volume for the hydrogen atoms increase linearly from near the lipid s polar head group to the end of its hydrophobic tail. Our results present a quantitative and detailed picture of the effect of the gel-fluid phase transition on the nanoscopic lipid dynamics in ULV. The data analysis approach developed here has a potential for probing the dynamic response of lipids to the presence of additional cell membrane components.
Object Tracking and Multimedia Augmented Transition Network for Video Indexing and Modeling
Chen, Shu-Ching
Object Tracking and Multimedia Augmented Transition Network for Video Indexing and Modeling Shu, IN 47907 kashyap@ecn.purdue.edu Abstract In our previous work, a multimedia augmented transition network (ATN) model together with its multimedia input strings were proposed to model and structure video data
Structural system identification: Structural dynamics model validation
Red-Horse, J.R.
1997-04-01T23:59:59.000Z
Structural system identification is concerned with the development of systematic procedures and tools for developing predictive analytical models based on a physical structure`s dynamic response characteristics. It is a multidisciplinary process that involves the ability (1) to define high fidelity physics-based analysis models, (2) to acquire accurate test-derived information for physical specimens using diagnostic experiments, (3) to validate the numerical simulation model by reconciling differences that inevitably exist between the analysis model and the experimental data, and (4) to quantify uncertainties in the final system models and subsequent numerical simulations. The goal of this project was to develop structural system identification techniques and software suitable for both research and production applications in code and model validation.
The dynamic radiation environment assimilation model (DREAM)
Reeves, Geoffrey D [Los Alamos National Laboratory; Koller, Josef [Los Alamos National Laboratory; Tokar, Robert L [Los Alamos National Laboratory; Chen, Yue [Los Alamos National Laboratory; Henderson, Michael G [Los Alamos National Laboratory; Friedel, Reiner H [Los Alamos National Laboratory
2010-01-01T23:59:59.000Z
The Dynamic Radiation Environment Assimilation Model (DREAM) is a 3-year effort sponsored by the US Department of Energy to provide global, retrospective, or real-time specification of the natural and potential nuclear radiation environments. The DREAM model uses Kalman filtering techniques that combine the strengths of new physical models of the radiation belts with electron observations from long-term satellite systems such as GPS and geosynchronous systems. DREAM includes a physics model for the production and long-term evolution of artificial radiation belts from high altitude nuclear explosions. DREAM has been validated against satellites in arbitrary orbits and consistently produces more accurate results than existing models. Tools for user-specific applications and graphical displays are in beta testing and a real-time version of DREAM has been in continuous operation since November 2009.
Hydro-dynamical models for the chaotic dripping faucet
P. Coullet; L. Mahadevan; C. S. Riera
2004-08-20T23:59:59.000Z
We give a hydrodynamical explanation for the chaotic behaviour of a dripping faucet using the results of the stability analysis of a static pendant drop and a proper orthogonal decomposition (POD) of the complete dynamics. We find that the only relevant modes are the two classical normal forms associated with a Saddle-Node-Andronov bifurcation and a Shilnikov homoclinic bifurcation. This allows us to construct a hierarchy of reduced order models including maps and ordinary differential equations which are able to qualitatively explain prior experiments and numerical simulations of the governing partial differential equations and provide an explanation for the complexity in dripping. We also provide a new mechanical analogue for the dripping faucet and a simple rationale for the transition from dripping to jetting modes in the flow from a faucet.
Transition from static to kinetic friction: Insights from a 2D model
Trmborg, Jrgen; Amundsen, David Sklid; Thgersen, Kjetil; Malthe-Srenssen, Anders
2013-01-01T23:59:59.000Z
We describe a 2D spring-block model for the transition from static to kinetic friction at an elastic slider/rigid substrate interface obeying a minimalistic friction law (Amontons-Coulomb). By using realistic boundary conditions, a number of previously unexplained experimental results on precursory micro-slip fronts are successfully reproduced. From the analysis of the interfacial stresses, we derive a prediction for the evolution of the precursor length as a function of the applied loads, as well as an approximate relationship between microscopic and macroscopic friction coefficients. We show that the stress build-up due to both elastic loading and micro-slip-related relaxations depend only weakly on the underlying shear crack propagation dynamics. Conversely, crack speed depends strongly on both the instantaneous stresses and the friction coefficients, through a non-trivial scaling parameter.
Size dependence, stability, and a transition to buckling in model reverse bilayers
J. Stecki
2006-07-03T23:59:59.000Z
Molecular Dynamics simulations of a model bilayer made of surfactant dimers in a Lennard-Jones solvent are reported for three sizes of the systems up to an area of $100\\sigma \\times 100\\sigma$ and for a large interval of specific areas:from hole formation under tension to the floppy state of a compressed bilayer. The transition to the floppy state appears quite abrupt and discontinuous; in the floppy state the lateral tension is negative. Lateral tension and the structure factor were determined for all 3 sizes and all areas; the apparent rigidity constant and apparent surface tension are determined and correlated with the specific area and the finite size. The replacement of the $1/q^2$ capillary-wave divergence by a pole is accounted for and explained. The derivative of the lateral tension jumps from a high value in a flat bilayer to a low value in the floppy, rough, and buckling state, where the tension itself is negative.
The quantum Biroli-Mzard model: glass transition and superfluidity in a quantum lattice glass model
Laura Foini; Guilhem Semerjian; Francesco Zamponi
2011-03-12T23:59:59.000Z
We study the quantum version of a lattice model whose classical counterpart captures the physics of structural glasses. We discuss the role of quantum fluctuations in such systems and in particular their interplay with the amorphous order developed in the glass phase. We show that quantum fluctuations might facilitate the formation of the glass at low enough temperature. We also show that the glass transition becomes a first-order transition between a superfluid and an insulating glass at very low temperature, and is therefore accompanied by phase coexistence between superfluid and glassy regions.
Direct modelling of envelope dynamics in resonant inverters
is to model the AC dynamics from input modulation to output envelops to facilitate optimised controller designDirect modelling of envelope dynamics in resonant inverters Y. Yin, R. Zane, R. Erickson and J. Glaser A direct dynamic modelling approach is proposed for envelope signals in resonant inverters
Analytical modeling of balloon launch dynamics
Strganac, Thomas W
1980-01-01T23:59:59.000Z
Subject; Aerospace Engineer1ng ANALYTICAL MODELING OF BALLOON LAUNCH DYNAMICS A Thesis by THOMAS WILLIAM STRGANAC Approved as to sty1e and content by: (Chairman of Committee) (Member) (Member) (Head of Dep rtment) December 1980 ABSTRACT Analyt1... aerodynam1cs. Actual fl1ght data has been used to qualify the model via comparisons of the launch trans1ent configurations. DEDICATION To my father. . THOMAS JOHN STRGANAC 1922-1980 . . . who provided me the examp1e to fo1Iow in life. ACKNOWLEDGEMENTS...
A Game-Theoretical Dynamic Model for Electricity Markets
Aswin Kannan
2010-10-06T23:59:59.000Z
Oct 6, 2010 ... Abstract: We present a game-theoretical dynamic model for competitive electricity markets.We demonstrate that the model can be used to...
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
aspects of the global oil market. One such constraint limitsthe opera- tion of the oil market. As an example, here weequations [7]). The oil market in ROMEO does not include in
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
of conventional petroleum production often assume thatalso interested in petroleum production because of carbonsupport production of substitutes for conventional petroleum
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
crude oil availabil- ity has the following results: less overall fuel consumption,crude-oil-equivalent fuels), the emissions penalty (in gigatonnes of carbon equivalent), and the total emissions from fuel production and consumption (
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
playing key role in peak-oil debate, future energy supply.of di?ering views of peak oil, including Yergins, isHubberts Peak: The Impending World Oil Shortage. Princeton
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
entirely from steam-induced heavy oil production in Cali-from Venezuelas extra-heavy oil reached about 0.6 Mbbl/d inliquid fuels. Heavy and extra-heavy oil are very viscous and
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
EOR continues to unlock oil resources. Oil & Gas Journal, [of conventional oil resource availability. Estimates ofthe tar sands and heavy oil resource in Figure 10. Note that
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
response to high oil prices and geopolitical threats tofor the e?ect of the oil price through the price elasticityprojections, corresponding oil price series are extracted
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
energy supply. Oil & Gas Journal. , 101(29):20, 2003. [40]unlock oil resources. Oil & Gas Journal, [31] NEB. Canadas
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
1] Andrews, S. and Udall, R. Oil Prophets: Lookingat World Oil Studies Over Time. In Campbell, C.International Workshop on Oil Depletion 2003, Paris, France,
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
D. J. and Cecchine, G. Oil shale development in the Unitedresources of some world oil-shale deposits. Technical Reportfor CO2 evolved from oil shale. Fuel Processing Technology,
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
based on projections of future prices and future demand.with demand projections, corresponding oil price series areoil price path associated with the IMAGE demand projection
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
Technical report, British Petrol- eum, June 2005. [5]long-run elasticities of petrol- Table 3: Parameter settings
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
J. Regular conventional oil production to 2100 and resource10% of total US oil production in 2004, almost entirelysteam-induced heavy oil production in Cali- fornia [30].
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
manufactured in two steps: a syngas comprised mainly of COfeedstock, then the syngas is converted into liquid fuel
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
testing their above-ground shale oil retorting technology.and Miller, G. A. Oil shales and carbon dioxide. Science, [D. J. and Cecchine, G. Oil shale development in the United
Dynamics of the Oil Transition: Modeling Capacity, Costs, and Emissions
Brandt, Adam R.; Farrell, Alexander E.
2008-01-01T23:59:59.000Z
oil-like hydrocarbon fuels from non-conventional petroleumto hydrocarbon-based substitutes for conventional petroleum.liquid hydrocarbons, avail- ability of conventional oil, the
Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9 5 -ofLearningLensless4
Dynamic nuclear polarization with simultaneous excitation of electronic and nuclear transitions
G. W. Morley; K. Porfyrakis; A. Ardavan; J. van Tol
2008-05-28T23:59:59.000Z
Dynamic nuclear polarization transfers spin polarization from electrons to nuclei. We have achieved this by a new method, simultaneously exciting transitions of electronic and nuclear spins. The efficiency of this technique improves with increasing magnetic field. Experimental results are shown for N@C60 with continuous-wave microwaves, which can be expected to produce even higher polarization than the corresponding pulsed techniques for electron spins greater than 1/2. The degree of nuclear polarization in this case can be easily monitored through the intensities of the well resolved hyperfine components in the EPR spectrum. The nuclear spin-lattice relaxation time is orders of magnitude longer than that of the electrons.
Phase Transition and Separation for Mixture of Liquid He-3 and He-4
Tian Ma; Shouhong Wang
2008-05-31T23:59:59.000Z
This article introduces a dynamical Ginzburg-Landau phase transition/separation model for the mixture of liquid helium-3 and helium-4, using a unified dynamical Ginzburg-Landau model for equilibrium phase transitions. The analysis of this model leads to three critical length scales L1 transition properties with different length scales of the container.
Rindlisbacher, Tobias
2015-01-01T23:59:59.000Z
The transition between the two phases of 4D Euclidean Dynamical Triangulation [1] was long believed to be of second order until in 1996 first order behavior was found for sufficiently large systems [5,9]. However, one may wonder if this finding was affected by the numerical methods used: to control volume fluctuations, in both studies [5,9] an artificial harmonic potential was added to the action; in [9] measurements were taken after a fixed number of accepted instead of attempted moves which introduces an additional error. Finally the simulations suffer from strong critical slowing down which may have been underestimated. In the present work, we address the above weaknesses: we allow the volume to fluctuate freely within a fixed interval; we take measurements after a fixed number of attempted moves; and we overcome critical slowing down by using an optimized parallel tempering algorithm [12]. With these improved methods, on systems of size up to 64k 4-simplices, we confirm that the phase transition is first ...
Dynamic density field measurements of an explosively driven ????? phase transition in iron
Hull, L. M.; Gray, G. T.; Warthen, B. J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
2014-07-28T23:59:59.000Z
We provide a unique set of observations of the behavior of the ??? phase transition under a complex axially symmetric loading path created by sweeping a detonation wave along the end surface of a cylindrical sample. The primary data sets are the measured mass density distributions acquired at 5 independent times during the sweep of the detonation along the surface. Shocked regions and boundaries are measured, as well as regions and boundaries of elevated density (presumed to be the ??phase iron). The formation and dynamics of these regions were captured and are available for comparisons to material descriptions. We also applied 16 Photon Doppler Velocimetry probes to capture the free surface velocity along a discrete set of radially distributed points in order to compare and correlate the density measurements with previous shock wave studies. The velocimetry data are in nearly exact agreement with previous shock wave studies of the ??? phase transition, the density distributions, while generally in agreement with expectations evolved from the shock wave studies, show that the epsilon phase is generated in regions of high shear stress but at hydrostatic stresses below the typically quoted 13?GPa value. The density field measurements are particularly useful for observing the effects of the forward and reverse transformation kinetics, as well as the reverse transformation hysteresis.
Dynamical Models for the Milky Way
Walter Dehnen; James Binney
1996-01-10T23:59:59.000Z
The only way to map the Galaxy's gravitational potential $\\Phi({\\bf x})$ and the distribution of matter that produces it is by modelling the dynamics of stars and gas. Observations of the kinematics of gas provide key information about gradients of $\\Phi$ within the plane, but little information about the structure of $\\Phi$ out of the plane. Traditional Galaxy models {\\em assume}, for each of the Galaxy's components, arbitrary flattenings, which together with the components' relative masses yield the model's equipotentials. However, the Galaxy's isopotential surfaces should be {\\em determined\\/} directly from the motions of stars that move far from the plane. Moreover, from the kinematics of samples of such stars that have well defined selection criteria, one should be able not only to map $\\Phi$ at all positions, but to determine the distribution function $f_i({\\bf x},{\\bf v})$ of each stellar population $i$ studied. These distribution functions will contain a wealth of information relevant to the formation and evolution of the Galaxy. An approach to fitting a wide class of dynamical models to the very heterogeneous body of available data is described and illustrated.
Colombo, Anthony P.
2013-01-01T23:59:59.000Z
We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of RydbergRydberg transitions is that they have enormous electric dipole transition ...
Gaoqing Cao; Lianyi He; Pengfei Zhuang
2014-09-16T23:59:59.000Z
It is known that a constant magnetic field is a strong catalyst of dynamical chiral symmetry breaking in 2+1 dimensions, leading to generating dynamical fermion mass even at weakest attraction. In this work we investigate the collective modes associated with the dynamical chiral symmetry breaking in a constant magnetic field in the (2+1)-dimensional Nambu--Jona-Lasinio model with continuous U(1) chiral symmetry. We introduce a self-consistent scheme to evaluate the propagators of the collective modes at the leading order in 1/N. The contributions from the vacuum and from the magnetic field are separated such that we can employ the well-established regularization scheme for the case of vanishing magnetic field. The same scheme can be applied to the study of the next-to-leading order correction in 1/N. We show that the sigma mode is always a lightly bound state with its mass being twice the dynamical fermion mass for arbitrary strength of the magnetic field. Since the dynamics of the collective modes is always 2+1 dimensional, the finite temperature transition should be of the Kosterlitz-Thouless (KT) type. We determine the KT transition temperature $T_{\\rm KT}$ as well as the mass melting temperature $T^*$ as a function of the magnetic field. It is found that the pseudogap domain $T_{\\rm KT}catalysis of the KT transition temperature in 2+1 dimensions. The inverse magnetic catalysis behavior is actually the de Haas--van Alphen oscillation induced by the interplay between the magnetic field and the Fermi surface.
Measuring the dynamic structure factor of a quantum gas undergoing a structural phase transition
Renate Landig; Ferdinand Brennecke; Rafael Mottl; Tobias Donner; Tilman Esslinger
2015-03-18T23:59:59.000Z
The dynamic structure factor is a central quantity describing the physics of quantum many-body systems, capturing structure and collective excitations of a material. In condensed matter, it can be measured via inelastic neutron scattering, which is an energy-resolving probe for the density fluctuations. In ultracold atoms, a similar approach could so far not be applied due to the diluteness of the system. Here, we report on a direct, real-time and non-destructive measurement of the dynamic structure factor of a quantum gas exhibiting cavity-mediated long-range interactions. The technique relies on inelastic scattering of photons, stimulated by the enhanced vacuum field inside a high finesse optical cavity. We extract the density fluctuations, their energy and lifetime while the system undergoes a structural phase transition. We observe an occupation of the relevant quasi-particle mode on the level of a few excitations, and provide a theoretical description of this dissipative quantum many-body system.
Modelling and simulation of multidisciplinary dynamic systems Lead: A. Fakri.
Baudoin, Geneviève
Modelling and simulation of multidisciplinary dynamic systems Lead: A. Fakri. Permanent members: P. Integration of various engineering disciplines and the consideration of the dynamic control need a concurrent suited for the energy exchanges to study multidisciplinary dynamic engineering systems modelling. Our
ONGOING RESEARCH PROJECTS Model of tropical forest structure and dynamics
Hill, Jeffrey E.
ONGOING RESEARCH PROJECTS Model of tropical forest structure and dynamics There is a need canopy structure and partitions dynamic rates for a tropical forest on Barro Colorado Island (BCI structure and partitions dynamic rates in a tropical forest. In Review. Journal of Ecology. #12;PPA model
Gradient Navigation Model for Pedestrian Dynamics
Felix Dietrich; Gerta Kster
2014-05-14T23:59:59.000Z
We present a new microscopic ODE-based model for pedestrian dynamics: the Gradient Navigation Model. The model uses a superposition of gradients of distance functions to directly change the direction of the velocity vector. The velocity is then integrated to obtain the location. The approach differs fundamentally from force based models needing only three equations to derive the ODE system, as opposed to four in, e.g., the Social Force Model. Also, as a result, pedestrians are no longer subject to inertia. Several other advantages ensue: Model induced oscillations are avoided completely since no actual forces are present. The derivatives in the equations of motion are smooth and therefore allow the use of fast and accurate high order numerical integrators. At the same time, existence and uniqueness of the solution to the ODE system follow almost directly from the smoothness properties. In addition, we introduce a method to calibrate parameters by theoretical arguments based on empirically validated assumptions rather than by numerical tests. These parameters, combined with the accurate integration, yield simulation results with no collisions of pedestrians. Several empirically observed system phenomena emerge without the need to recalibrate the parameter set for each scenario: obstacle avoidance, lane formation, stop-and-go waves and congestion at bottlenecks. The density evolution in the latter is shown to be quantitatively close to controlled experiments. Likewise, we observe a dependence of the crowd velocity on the local density that compares well with benchmark fundamental diagrams.
Quantum phase transitions in fully connected spin models: an entanglement perspective
M. Filippone; S. Dusuel; J. Vidal
2011-02-28T23:59:59.000Z
We consider a set of fully connected spins models that display first- or second-order transitions and for which we compute the ground-state entanglement in the thermodynamical limit. We analyze several entanglement measures (concurrence, R\\'enyi entropy, and negativity), and show that, in general, discontinuous transitions lead to a jump of these quantities at the transition point. Interestingly, we also find examples where this is not the case.
Quantum phase transitions in fully-connected spin models: an entanglement perspective
Filippone, M; Vidal, J
2011-01-01T23:59:59.000Z
We consider a set of fully-connected spins models which display first- or second-order transitions and for which we compute the ground-state entanglement in the thermodynamical limit. We analyze several entanglement measures (concurrence, R\\'enyi entropy, and negativity), and show that, in general, discontinuous transitions leads to a jump of these quantities at the transition point. Interestingly, we also find a puzzling example where it is not the case.
Unbounded dynamics in dissipative flows: Rssler model
Barrio, Roberto, E-mail: rbarrio@unizar.es; Serrano, Sergio, E-mail: sserrano@unizar.es [Computational Dynamics Group, Dpto. Matemtica Aplicada and IUMA, Universidad de Zaragoza, E-50009 Zaragoza (Spain)] [Computational Dynamics Group, Dpto. Matemtica Aplicada and IUMA, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Blesa, Fernando, E-mail: fblesa@unizar.es [Computational Dynamics Group, Dpto. Fsica Aplicada and IUMA, Universidad de Zaragoza, E-50009 Zaragoza (Spain)] [Computational Dynamics Group, Dpto. Fsica Aplicada and IUMA, Universidad de Zaragoza, E-50009 Zaragoza (Spain)
2014-06-15T23:59:59.000Z
Transient chaos and unbounded dynamics are two outstanding phenomena that dominate in chaotic systems with large regions of positive and negative divergences. Here, we investigate the mechanism that leads the unbounded dynamics to be the dominant behavior in a dissipative flow. We describe in detail the particular case of boundary crisis related to the generation of unbounded dynamics. The mechanism of the creation of this crisis in flows is related to the existence of an unstable focus-node (or a saddle-focus) equilibrium point and the crossing of a chaotic invariant set of the system with the weak-(un)stable manifold of the equilibrium point. This behavior is illustrated in the well-known Rssler model. The numerical analysis of the system combines different techniques as chaos indicators, the numerical computation of the bounded regions, and bifurcation analysis. For large values of the parameters, the system is studied by means of Fenichel's theory, providing formulas for computing the slow manifold which influences the evolution of the first stages of the orbit.
Dynamics of an Economics Model for Generation Coupled to the OPA Power Transmission Model
Dobson, Ian
Dynamics of an Economics Model for Generation Coupled to the OPA Power Transmission Model B. A a dynamic model of the power transmission system (OPA) and a simple economic model of power generation development. Despite the simplicity of this economic model, complex dynamics both in the economics (prices
Linking Dynamical and Population Genetic Models of Persistent Viral Infection
Kelly, John K.; Williamson, Scott; Orive, Maria E.; Smith, Marilyn S.; Holt, Robert D.
2003-07-01T23:59:59.000Z
This article develops a theoretical framework to link dynamical and population genetic models of persistent viral infection. This linkage is useful because, while the dynamical and population genetic theories have developed ...
Phase Transition in Ferromagnetic Ising Models with Non-Uniform External Magnetic Fields
Rodrigo Bissacot; Leandro Cioletti
2010-03-29T23:59:59.000Z
In this article we study the phase transition phenomenon for the Ising model under the action of a non-uniform external magnetic field. We show that the Ising model on the hypercubic lattice with a summable magnetic field has a first-order phase transition and, for any positive (resp. negative) and bounded magnetic field, the model does not present the phase transition phenomenon whenever $\\liminf h_i> 0$, where ${\\bf h} = (h_i)_{i \\in \\Z^d}$ is the external magnetic field.
Solid Oxide Fuel Cell: Perspective of Dynamic Modeling and Control
Huang, Biao
Solid Oxide Fuel Cell: Perspective of Dynamic Modeling and Control Biao Huang Yutong Qi Monjur: This paper presents a review of state-of-the-art solid oxide fuel cells (SOFC), from perspective of dynamic. Keywords: Solid Oxide Fuel Cell, Control Relevant Model, Model Predictive Control 1. INTRODUCTION Today
Dynamic Bayesian Networks model to estimate process availability.
Paris-Sud XI, Universit de
Dynamic Bayesian Networks model to estimate process availability. Weber P. Centre de Recherche en reported here explores a new methodology to develop Dynamic Bayesian Network-based Availability of the system availability estimation comparing DBN model with the classical Markov chain model. Keywords
Modeling Transit Trip Time Using Archived Bus Dispatch System Data
Bertini, Robert L.
Transportation District of Oregon TriMet provides transit service in the three-county Portland metropolitan area that are automatically collected and archived for each bus, route, and stop every day. The Tri-County Metropolitan. TriMet has implemented a Bus Dispatch System BDS as a part of its overall service control
Paris-Sud XI, Universit de
Non-linear inversion modeling for Ultrasound Computer Tomography: transition from soft to hard Marseille cedex 20, France ABSTRACT Ultrasound Computer Tomography (UCT) is an imaging technique which has experiments. Keyword: Ultrasound Computer Tomography, Inverse Born Approximation, Elliptical Projection
Coarse-grained simulations of vortex dynamics and transition in complex high-Re flows
Grinstein, Fernando F [Los Alamos National Laboratory
2011-01-21T23:59:59.000Z
Turbulent flow complexity in applications in engineering, geophysics and astrophysics typically requires achieving accurate and dependable large scale predictions of highly nonlinear processes with under-resolved computer simulation models. Laboratory observations typically demonstrate the end outcome of complex non-linear three-dimensional physical processes with many unexplained details and mechanisms. Carefully controlled computational experiments based on the numerical solution of the conservation equations for mass, momentum, and energy, provide insights into the underlying flow dynamics. Relevant computational fluid dynamics issues to be addressed relate to the modeling of the unresolved tlow conditions at the subgrid scale (SGS) level - within a computational cell, and at the supergrid (SPG) scale - at initialization and beyond computational boundaries. SGS and SPG information must be prescribed for closure of the equations solved numerically. SGS models appear explicitly or implicitly as additional source tenns in the modified flow equations solved by the numerical solutions being calculated, while SPG models provide the necessary set of initial and boundary conditions that must be prescribed to ensure unique well-posed solutions. From this perspective, it is clear that the simulation process is inherently determined by the SGS and SPG information prescription process. On the other hand, observables in laboratory experiments are always characterized by the finite scales of the instrumental resolution of measuring/visualizing devices, and subject as well to SPG issues. It is thus important to recognize the inherently intrusive nature of observations based on numerical or laboratory experiments. Ultimately, verification and validation (V & V) frameworks and appropriate metrics for the specific problems at hand are needed to establish predictability of the simulation model. Direct numerical simulation (DNS) - resolving all relevant space/time scales, is prohibitively expensive in the foreseeable future for most practical flows of interest at moderate-to-high Reynolds number (Re). On the other end of the simulation spectrum are the Reynolds-Averaged Navier-Stokes (RANS) approaches - which model the turbulent effects. In the coarsegrained large eddy simulation (LES) strategies, the large energy containing structures are resolved, the smaller structures are filtered out, and unresolved SGS effects are modeled. By necessity - rather than choice, LES effectively becomes the intermediate approach between DNS and RANS. Extensive work has demonstrated that predictive simulations of turbulent velocity fields are possible using a particular LES denoted implicit LES (ILES), using the class of nonoscillatory finite-volume (NFV) numerical algorithms. Use of the modified equation as framework for theoretical analysis, demonstrates that leading truncation tenns associated with NFV methods provide implicit SGS models of mixed anisotropic type and regularized motion of discrete observables. Tests in fundamental applications ranging from canonical to very complex flows indicate that ILES is competitive with conventional LES in the LES realm proper - flows driven by large scale features. High-Re flows are vortex dominated and governed by short convective timescales compared to those of diffusion, and kinematically characterized at the smallest scales by slender worm vortices with insignificant internal structure. This motivates nominally inviscid ILES methods capable of capturing the high-Re dissipation dynamics and of handling vortices as shocks in shock capturing schemes. Depending on flow regimes, initial conditions, and resolution, additional modeling may be needed to emulate SGS driven physics, such as backscatter, chemical reaction, material mixing, and near-wall flow-dynamics - where typically-intertwined SGS/SPG issues need to be addressed. A major research focus is recognizing when additional explicit models and/or numerical treatments are needed and ensuring that mixed explicit and implicit SGS models can effectively act in
Husimi distribution and phase space analysis of Dicke model quantum phase transition
E. Romera; R. del Real; M. Calixto
2014-09-19T23:59:59.000Z
The Husimi distribution is proposed for a phase space analysis of quantum phase transitions in the Dicke model of spin-boson interactions. We show that the inverse participation ratio and Wehrl entropy of the Husimi distribution give sharp signatures of the quantum phase transition. The analysis has been done using two frameworks: a numerical treatment and an analytical variational approximation. Additionally we have proposed a new characterization of the Dicke model quantum phase transition by means of the zeros of the Husimi distribution in the variational approach.
Albert, Rka
with a random network with a given degree distribution P(k). Mark edges with probability T. DisregardThe two faces of network dynamics Evolving network models describe the dynamics (assembly, evolution) OF networks by the addition/removal of nodes and edges. It is possible to have network dynamics
A dynamic model for the Lagrangian stochastic dispersion coefficient
Pesmazoglou, I.; Navarro-Martinez, S., E-mail: s.navarro@imperial.ac.uk [Department of Mechanical Engineering, Imperial College, London SW7 2AZ (United Kingdom); Kempf, A. M. [Chair of Fluid Dynamics, Institute for Combustion and Gasdynamics and Center for Computational Sciences and Simulation, Universitt Duisburg-Essen, Duisburg, 47048 (Germany)] [Chair of Fluid Dynamics, Institute for Combustion and Gasdynamics and Center for Computational Sciences and Simulation, Universitt Duisburg-Essen, Duisburg, 47048 (Germany)
2013-12-15T23:59:59.000Z
A stochastic sub-grid model is often used to accurately represent particle dispersion in turbulent flows using large eddy simulations. Models of this type have a free parameter, the dispersion coefficient, which is not universal and is strongly grid-dependent. In the present paper, a dynamic model for the evaluation of the coefficient is proposed and validated in decaying homogeneous isotropic turbulence. The grid dependence of the static coefficient is investigated in a turbulent mixing layer and compared to the dynamic model. The dynamic model accurately predicts dispersion statistics and resolves the grid-dependence. Dispersion statistics of the dynamically calculated constant are more accurate than any static coefficient choice for a number of grid spacings. Furthermore, the dynamic model produces less numerical artefacts than a static model and exhibits smaller sensitivity in the results predicted for different particle relaxation times.
Event-Based Approach to Modelling Dynamic Architecture
Paris-Sud XI, Université de
Event-Based Approach to Modelling Dynamic Architecture: Application to Mobile Ad-Hoc Network.Attiogbe@univ-nantes.fr Abstract. We describe an event-based approach to specifiy systems with dynamically evolving architecture tools. Keywords: Specification, Verification, Dynamic Architecture, Event B. 1 Introduction Distributed
Stochastic modeling of lift and drag dynamics under turbulent conditions
Peinke, Joachim
measurement. The model is being developed with the aim to integrate it into a general wind energy converter dynamics, drag dynamics. 1 Introduction Wind energy converters (WECs) are permanently exposed to turbulent.peinke@forwind.de in every second, which imposes different risks. The dynamical nature of the wind has a significant impact
Dynamics and control of internal transport barriers in reversed shear discharges
Newman, David
Dynamics and control of internal transport barriers in reversed shear discharges D. E. Newman, B. A to a transport model in order to investigate the dynamics of the transition to this enhanced confinement mode profiles, a rich variety of transition dynamics is uncovered. Transition dynamics and their concomitant
Wai Lim Ku; Michelle Girvan; Edward Ott
2014-12-11T23:59:59.000Z
In this paper, we study dynamical systems in which a large number $N$ of identical Landau-Stuart oscillators are globally coupled via a mean-field. Previously, it has been observed that this type of system can exhibit a variety of different dynamical behaviors including clumped states in which each oscillator is in one of a small number of groups for which all oscillators in each group have the same state which is different from group to group, as well as situations in which all oscillators have different states and the macroscopic dynamics of the mean field is chaotic. We argue that this second type of behavior is $^{\\backprime}$extensive$^{\\prime}$ in the sense that the chaotic attractor in the full phase space of the system has a fractal dimension that scales linearly with $N$ and that the number of positive Lyapunov exponents of the attractor also scales with linearly $N$. An important focus of this paper is the transition between clumped states and extensive chaos as the system is subjected to slow adiabatic parameter change. We observe explosive (i.e., discontinuous) transitions between the clumped states (which correspond to low dimensional dynamics) and the extensively chaotic states. Furthermore, examining the clumped state, as the system approaches the explosive transition to extensive chaos, we find that the oscillator population distribution between the clumps continually evolves so that the clumped state is always marginally stable. This behavior is used to reveal the mechanism of the explosive transition. We also apply the Kaplan-Yorke formula to study the fractal structure of the extensively chaotic attractors.
Factoring Gaussian Precision Matrices for Linear Dynamic Models
Frankel, Joe; King, Simon
2007-01-01T23:59:59.000Z
The linear dynamic model (LDM), also known as the Kalman filter model, has been the subject of research in the engineering, control, and more recently, machine learning and speech technology communities. The Gaussian noise processes are usually...
Quantum-information approach to the quantum phase transition in the Kitaev honeycomb model
Cui Jian; Cao Junpeng; Fan Heng [Institute of Physics, Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matter Physics, Beijing 100190 (China)
2010-08-15T23:59:59.000Z
The Kitaev honeycomb model with a topological phase transition at zero temperature is studied using the quantum-information method. Based on the exact solution of the ground state, the mutual information between two nearest sites and between two bonds with the greatest distance are obtained. It is found that the mutual information shows some singularities at the critical point where the system transits from the gapless phase to the gapped phase. Finite-size effects and scaling behavior are also studied. Our results indicate that the mutual information can serve as a good indicator of the topological phase transition. This is because the mutual information is believed to be able to catch some global correlation properties of the system. Meanwhile, this method has the advantages that the phase transition can be determined easily and the order parameters, which are hard to obtain for some topological phase transitions, are not necessarily known.
Static and Dynamic Debugging of Modelica Models Adrian Pop1
Zhao, Yuxiao
Static and Dynamic Debugging of Modelica Models Adrian Pop1 , Martin Sjlund1 , Adeel Asghar1@elet.polimi.it Abstract The high abstraction level of equation-based object- oriented languages (EOO) such as Modelica has and dynamic debugging methods for Modelica models and a debugger prototype that addresses several of those
A New Motorcycle Simulator Platform: Mechatronics Design, Dynamics Modeling
Paris-Sud XI, Universit de
A New Motorcycle Simulator Platform: Mechatronics Design, Dynamics Modeling and Control L. Nehaoua and dynamics modeling will be presented. Some results are shown, validating the actutation requirements and platform control. 1. INTRODUCTION Road safety has become a major political and economical issue. While all
A Qualitative Simulation Approach for Fuzzy Dynamical Models
Bontempi, Gianluca
.g., a nuclear power plant in unexpected emergency situations) or because if does not yet exist (eA Qualitative Simulation Approach for Fuzzy Dynamical Models ANDREA BONARINI and GIANLUCA BONTEMPI Politecnico di Milano This article deal with simulation of approximate models of dynamic systems. We propose
Computational Modeling of Brain Dynamics during Repetitive Head Motions
Burtscher, Martin
Computational Modeling of Brain Dynamics during Repetitive Head Motions Igor Szczyrba School the HIC scale to arbitrary head motions. Our simulations of the brain dynamics in sagittal and horizontal injury modeling, resonance effects 1 Introduction A rapid head motion can result in a severe brain injury
A Dynamic Model of Social Network Formation Brian Skyrms 1
Pemantle, Robin
A Dynamic Model of Social Network Formation Brian Skyrms 1 Robin Pemantle 2;3 ABSTRACT: We consider a dynamic social network model in which agents play repeated games in pairings determined by a stochastically evolving social network. In- dividual agents begin to interact at random, with the interactions
MODELLING THE ONSET OF DYNAMIC Importance of the Vertical Dimension
Johansen, Tom Henning
block models of an elastic slider under dry friction. I apply AmontonsCoulomb friction at the block levelMODELLING THE ONSET OF DYNAMIC FRICTION Importance of the Vertical Dimension by JRGEN TRMBORG of the onset of dynamic friction. Optical methods give access to the sliding interface before and during
DAbramo, Marco [Supercomputing Applications and Innovation, CINECA, Via dei Tizii, 6, 00185 Rome (Italy) [Supercomputing Applications and Innovation, CINECA, Via dei Tizii, 6, 00185 Rome (Italy); Dipartimento di Chimica, Universit Sapienza, P.le Aldo Moro, 5, 00185, Rome (Italy); Aschi, Massimiliano [Department of Physical and Chemical Sciences, University of Aquila, via Vetoio (Coppito 1), 67010 Aquila (Italy)] [Department of Physical and Chemical Sciences, University of Aquila, via Vetoio (Coppito 1), 67010 Aquila (Italy); Amadei, Andrea, E-mail: andrea.amadei@uniroma2.it [Dipartimento di Scienze e Tecnologie Chimiche Universita di Roma, Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy)] [Dipartimento di Scienze e Tecnologie Chimiche Universita di Roma, Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy)
2014-04-28T23:59:59.000Z
Here, we extend a recently introduced theoretical-computational procedure [M. DAlessandro, M. Aschi, C. Mazzuca, A. Palleschi, and A. Amadei, J. Chem. Phys. 139, 114102 (2013)] to include quantum vibrational transitions in modelling electronic spectra of atomic molecular systems in condensed phase. The method is based on the combination of Molecular Dynamics simulations and quantum chemical calculations within the Perturbed Matrix Method approach. The main aim of the presented approach is to reproduce as much as possible the spectral line shape which results from a subtle combination of environmental and intrinsic (chromophore) mechanical-dynamical features. As a case study, we were able to model the low energy UV-vis transitions of pyrene in liquid acetonitrile in good agreement with the experimental data.
Winding Transitions at Finite Energy and Temperature: An O(3) Model
Salman Habib; Emil Mottola; Peter Tinyakov
1996-08-14T23:59:59.000Z
Winding number transitions in the two dimensional softly broken O(3) nonlinear sigma model are studied at finite energy and temperature. New periodic instanton solutions which dominate the semiclassical transition amplitudes are found analytically at low energies, and numerically for all energies up to the sphaleron scale. The Euclidean period beta of these finite energy instantons increases with energy, contrary to the behavior found in the abelian Higgs model or simple one dimensional systems. This results in a sharp crossover from instanton dominated tunneling to sphaleron dominated thermal activation at a certain critical temperature. Since this behavior is traceable to the soft breaking of conformal invariance by the mass term in the sigma model, semiclassical winding number transition amplitudes in the electroweak theory in 3+1 dimensions should exhibit a similar sharp crossover. We argue that this is indeed the case in the standard model for M_H < 4 M_W.
Texas at Austin. University of
in Lennard-Jonesium and Tin J. M. D. Lane and M. P. Marder Center for Nonlinear Dynamics, University of Texas for shocks in tin which agrees to within 6% with experimental data. We study the strong shock to elastic-plastic shock transition in tin and find that it is a continuous transition consistent with a transcritical
Dynamic Modeling of Cascading Failure in Power Systems
Song, Jiajia; Ghanavati, Goodarz; Hines, Paul D H
2014-01-01T23:59:59.000Z
The modeling of cascading failure in power systems is difficult because of the many different mechanisms involved; no single model captures all of these mechanisms. Understanding the relative importance of these different mechanisms is an important step in choosing which mechanisms need to be modeled for particular types of cascading failure analysis. This work presents a dynamic simulation model of both power networks and protection systems, which can simulate a wider variety of cascading outage mechanisms, relative to existing quasi-steady state (QSS) models. The model allows one to test the impact of different load models and protections on cascading outage sizes. This paper describes each module of the developed dynamic model and demonstrates how different mechanisms interact. In order to test the model we simulated a batch of randomly selected $N-2$ contingencies for several different static load configurations, and found that the distribution of blackout sizes and event lengths from the proposed dynamic...
Dynamic Modeling in Solid-Oxide Fuel Cells Controller Design
Lu, Ning; Li, Qinghe; Sun, Xin; Khaleel, Mohammad A.
2007-06-28T23:59:59.000Z
In this paper, a dynamic model of the solid-oxide fuel cell (SOFC) power unit is developed for the purpose of designing a controller to regulate fuel flow rate, fuel temperature, air flow rate, and air temperature to maintain the SOFC stack temperature, fuel utilization rate, and voltage within operation limits. A lumped model is used to consider the thermal dynamics and the electro-chemial dynamics inside an SOFC power unit. The fluid dynamics at the fuel and air inlets are considered by using the in-flow ramp-rates.
Dobson, Ian
Critical points and transitions in an electric power transmission model for cascading failure September 2002 Cascading failures in large-scale electric power transmission systems are an important cause, we examine cascading failure in a simplified transmission system model as load power demand
A Phase Transition Model for By Christopher L. DeMarco
by the electric power systems application. Efforts to date on these problems for power networks have focused circuits (including nonlinear inductive and capacitive elements) and classical models for electric powerA Phase Transition Model for By Christopher L. DeMarco A s the scale of engineered systems
Modeling ramp compression experiments using large-scale molecular dynamics simulation.
Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)
2011-10-01T23:59:59.000Z
Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.
Fabrycky, Daniel C.; /UC, Santa Cruz; Ford, Eric B.; /Florida U.; Steffen, Jason H.; /Fermilab; Rowe, Jason F.; /SETI Inst., Mtn. View /NASA, Ames; Carter, Joshua A.; /Harvard-Smithsonian Ctr. Astrophys.; Moorhead, Althea V.; /Florida U.; Batalha, Natalie M.; /San Jose State U.; Borucki, William J.; /NASA, Ames; Bryson, Steve; /NASA, Ames; Buchhave, Lars A.; /Bohr Inst. /Copenhagen U.; Christiansen, Jessie L.; /SETI Inst., Mtn. View /NASA, Ames /Caltech
2012-01-01T23:59:59.000Z
Eighty planetary systems of two or more planets are known to orbit stars other than the Sun. For most, the data can be sufficiently explained by non-interacting Keplerian orbits, so the dynamical interactions of these systems have not been observed. Here we present 4 sets of lightcurves from the Kepler spacecraft, which each show multiple planets transiting the same star. Departure of the timing of these transits from strict periodicity indicates the planets are perturbing each other: the observed timing variations match the forcing frequency of the other planet. This confirms that these objects are in the same system. Next we limit their masses to the planetary regime by requiring the system remain stable for astronomical timescales. Finally, we report dynamical fits to the transit times, yielding possible values for the planets masses and eccentricities. As the timespan of timing data increases, dynamical fits may allow detailed constraints on the systems architectures, even in cases for which high-precision Doppler follow-up is impractical.
Slow dynamics in supercooled liquids : matrix formalism, mode coupling and glass transition
Wu, Jianlan, 1976-
2004-01-01T23:59:59.000Z
In this thesis, slow dynamics of supercooled liquids are investigated in the framework of the mode-coupling theory (MCT). Following the real-time generalized Langevin equation in Newtonian liquids, the dynamic Gaussian ...
Paris-Sud XI, Université de
Transition probabilities for piecewise affine models of genetic networks Madalena Chaves, Etienne that trajectories follow a path in a transition graph. In this paper, a probabilistic interpretation is given for the transition between two nodes A and B, based on the volume of the initial conditions on hyperrectangle A whose
Generic solar photovoltaic system dynamic simulation model specification.
Ellis, Abraham; Behnke, Michael Robert; Elliott, Ryan Thomas
2013-10-01T23:59:59.000Z
This document is intended to serve as a specification for generic solar photovoltaic (PV) system positive-sequence dynamic models to be implemented by software developers and approved by the WECC MVWG for use in bulk system dynamic simulations in accordance with NERC MOD standards. Two specific dynamic models are included in the scope of this document. The first, a Central Station PV System model, is intended to capture the most important dynamic characteristics of large scale (> 10 MW) PV systems with a central Point of Interconnection (POI) at the transmission level. The second, a Distributed PV System model, is intended to represent an aggregation of smaller, distribution-connected systems that comprise a portion of a composite load that might be modeled at a transmission load bus.
Coherent/incoherent metal transition in a holographic model
Keun-Young Kim; Kyung Kiu Kim; Yunseok Seo; Sang-Jin Sin
2014-12-13T23:59:59.000Z
We study AC electric($\\sigma$), thermoelectric($\\alpha$), and thermal($\\bar{\\kappa}$) conductivities in a holographic model, which is based on 3+1 dimensional Einstein-Maxwell-scalar action. There is momentum relaxation due to massless scalar fields linear to spatial coordinate. The model has three field theory parameters: temperature($T$), chemical potential($\\mu$), and effective impurity($\\beta$). At low frequencies, if $\\beta \\mu$ the shape of peak deviates from the Drude form(incoherent metal). At intermediate frequencies($T<\\omega<\\mu$), we have analysed numerical data of three conductivities($\\sigma, \\alpha, \\bar{\\kappa}$) for a wide variety of parameters, searching for scaling laws, which are expected from either experimental results on cuprates superconductors or some holographic models. In the model we study, we find no clear signs of scaling behaviour.
Model study of dissipation in quantum phase transitions
Subhasis Sinha; Sushanta Dattagupta
2011-04-28T23:59:59.000Z
We consider a prototypical system of an infinite range transverse field Ising model coupled to a bosonic bath. By integrating out the bosonic degrees, an effective anisotropic Heisenberg model is obtained for the spin system. The phase diagram of the latter is calculated as a function of coupling to the heat bath and the transverse magnetic field. Collective excitations at low temeratures are assessed within a spin-wave like analysis that exhibits a vanishing energy gap at the quantum critical point. We also consider another limit where the system reduces to a generalized spin-boson model of two interacting spins. By increasing the coupling strength with the heat bath, the two-spin wavefunction changes from an entangled state to a factorized state of two spins which are aligned along the transverse field. We also discuss the possible realization and application of the model to different physical systems.
Quantum phase transition in the $Z_3$ Kitaev-Potts model
Razieh Mohseninia; Saeed S. Jahromi; Laleh Memarzadeh; Vahid Karimipour
2015-05-21T23:59:59.000Z
The stability of the topological order phase induced by the $Z_3$ Kitaev model, which is a candidate for fault-tolerant quantum computation, against the local order phase induced by the 3-State Potts model is studied. We show that the low energy sector of the Kitaev-Potts model is mapped to the Potts model in the presence of transverse magnetic field. Our study relies on two high-order series expansion based on continuous unitary transformations in the limits of small- and large-Potts couplings as well as mean-field approximation. Our analysis reveals that the topological phase of the $Z_3$ Kitaev model breaks down to the Potts model through a first order phase transition. We capture the phase transition by analysis of the ground state energy, one-quasiparticle gap and geometric measure of entanglement.
Optimal control with adaptive internal dynamics models
Mitrovic, Djordje; Klanke, Stefan; Vijayakumar, Sethu
2008-01-01T23:59:59.000Z
Optimal feedback control has been proposed as an attractive movement generation strategy in goal reaching tasks for anthropomorphic manipulator systems. The optimal feedback control law for systems with non-linear dynamics ...
Transition from AdS universe to DS universe in the BPP model
Wontae Kim; Myungseok Yoon
2007-03-03T23:59:59.000Z
It can be shown that in the BPP model the smooth phase transition from the asymptotically decelerated AdS universe to the asymptotically accelerated DS universe is possible by solving the modified semiclassical equations of motion. This transition comes from noncommutative Poisson algebra, which gives the constant curvature scalars asymptotically. The decelerated expansion of the early universe is due to the negative energy density with the negative pressure induced by quantum back reaction, and the accelerated late-time universe comes from the positive energy and the negative pressure which behave like dark energy source in recent cosmological models.
Ultrafast transmission electron microscopy on dynamic process of a CDW transition in 1T-TaSe2
Sun, Shuaishuai; Li, Zhongwen; Cao, Gaolong; Liu, Y; Lu, W J; Sun, Y P; Tian, Huanfang; HuaixinYang,; Li, Jianqi
2015-01-01T23:59:59.000Z
Four-dimensional ultrafast transmission electron microscopy (4D-UTEM) measurements reveal a rich variety of structural dynamic phenomena at a phase transition in the charge-density-wave (CDW) 1T-TaSe2. Through the photoexcitation, remarkable changes on both the CDW intensity and orientation are clearly observed associated with the transformation from a commensurate (C) into an incommensurate (IC) phase in a time-scale of about 3 ps. Moreover, the transient states show up a notable "structurally isosbestic point" at a wave vector of qiso where the C and IC phases yield their diffracting efficiencies in an equally ratio. This fact demonstrates that the crystal planes parallel to qiso adopts visibly common structural features in these two CDW phases. The second-order characters observed in this nonequilibrium phase transition have been also analyzed based on the time-resolved structural data.
REGULAR ARTICLE A Simple Dynamic Model of Respiratory Pump
Fontecave-Jallon, Julie
). Mathematical models are used to understand these interactions and the mechanics of respiratory system better) and introduce some dynamic properties of the respiratory system. The passive elements (rib cage and abdomen not take into account the dynamic component of the system, it appears valid for different respiratory
Modeling and Management of Nonlinear Dependencies Copulas in Dynamic Financial
Ulm, Universitt
an important tool for decision making and an essential part of enterprise risk management (ERM), particularly. Keywords: Non-Life Insurance, Risk Management, Dynamic Financial Analysis, Co- pulas, PerformanceModeling and Management of Nonlinear Dependencies Copulas in Dynamic Financial Analysis Martin
UNEDITED PREPRINT Building a dynamic growth model for trembling
Garca, Oscar
UNEDITED PREPRINT Building a dynamic growth model for trembling aspen in Western Canada without age for even-aged thinned or unthinned stands dominated by trembling aspen. Estimation used permanent sample words: Forest growth and yield, Populus tremuloides, quacking aspen, thinning, dynamical systems, TAG. 1
Dynamic wind turbine models in power system simulation tool
Dynamic wind turbine models in power system simulation tool DIgSILENT Anca D. Hansen, Florin Iov Iov, Poul Sørensen, Nicolaos Cutululis, Clemens Jauch, Frede Blaabjerg Title: Dynamic wind turbine system simulation tool PowerFactory DIgSILENT for different wind turbine concepts. It is the second
Lin, Zhenhong; Ogden, J; Fan, Yueyue; Sperling, Dan
2006-01-01T23:59:59.000Z
Zoia (2005). "Hydrogen infrastructure strategic planningITSRR0605 The Hydrogen Infrastructure Transition Model (a 50-year Hydrogen Infrastructure for Urban Beijing Zhenhong
Lin, Zhenhong; Ogden, Joan M; Fan, Yueyue; Sperling, Dan
2006-01-01T23:59:59.000Z
Zoia (2005). "Hydrogen infrastructure strategic planningITSRR0605 The Hydrogen Infrastructure Transition Model (a 50-year Hydrogen Infrastructure for Urban Beijing Zhenhong
Weeks, Eric R.
Equivalence of Glass Transition and Colloidal Glass Transition in the Hard-Sphere Limit Ning Xu,1 that the slowing of the dynamics in simulations of several model glass-forming liquids is equivalent to the hard-sphere glass transition in the low-pressure limit. In this limit, we find universal behavior of the relaxation
Symbolic Dynamics in a Matching Labour Market Model
Diana A. Mendes; Vivaldo M. Mendes; J. Sousa Ramos
2006-08-01T23:59:59.000Z
In this paper we apply the techniques of symbolic dynamics to the analysis of a labor market which shows large volatility in employment flows. In a recent paper, Bhattacharya and Bunzel \\cite{BB} have found that the discrete time version of the Pissarides-Mortensen matching model can easily lead to chaotic dynamics under standard sets of parameter values. To conclude about the existence of chaotic dynamics in the numerical examples presented in the paper, the Li-Yorke theorem or the Mitra sufficient condition were applied which seems questionable because they may lead to misleading conclusions. Moreover, in a more recent version of the paper, Bhattacharya and Bunzel \\cite{BB1} present new results in which chaos is completely removed from the dynamics of the model. Our paper explores the matching model so interestingly developed by the authors with the following objectives in mind: (i) to show that chaotic dynamics may still be present in the model for standard parameter values; (ii) to clarify some open questions raised by the authors in \\cite{BB}, by providing a rigorous proof of the existence of chaotic dynamics in the model through the computation of topological entropy in a symbolic dynamics setting.
Capacity planning in a transitional economy: What issues? Which models?
Mubayi, V.; Leigh, R.W. [Brookhaven National Lab., Upton, NY (United States); Bright, R.N. [Anylec Research, Inc., Bayport, NY (United States)
1996-03-01T23:59:59.000Z
This paper is devoted to an exploration of the important issues facing the Russian power generation system and its evolution in the foreseeable future and the kinds of modeling approaches that capture those issues. These issues include, for example, (1) trade-offs between investments in upgrading and refurbishment of existing thermal (fossil-fired) capacity and safety enhancements in existing nuclear capacity versus investment in new capacity, (2) trade-offs between investment in completing unfinished (under construction) projects based on their original design versus investment in new capacity with improved design, (3) incorporation of demand-side management options (investments in enhancing end-use efficiency, for example) within the planning framework, (4) consideration of the spatial dimensions of system planning including investments in upgrading electric transmission networks or fuel shipment networks and incorporating hydroelectric generation, (5) incorporation of environmental constraints and (6) assessment of uncertainty and evaluation of downside risk. Models for exploring these issues include low power shutdown (LPS) which are computationally very efficient, though approximate, and can be used to perform extensive sensitivity analyses to more complex models which can provide more detailed answers but are computationally cumbersome and can only deal with limited issues. The paper discusses which models can usefully treat a wide range of issues within the priorities facing decision makers in the Russian power sector and integrate the results with investment decisions in the wider economy.
2.003 Modeling Dynamics and Control I, Spring 2002
Trumper, David L.
First of two-term sequence on modeling, analysis and control of dynamic systems. Mechanical translation, uniaxial rotation, electrical circuits and their coupling via levers, gears and electro-mechanical devices. Analytical ...
Human Growth and Body Weight Dynamics: An Integrative Systems Model
Rahmandad, Hazhir
Quantifying human weight and height dynamics due to growth, aging, and energy balance can inform clinical practice and policy analysis. This paper presents the first mechanism-based model spanning full individual life and ...
Molecular Dynamics Modeling of Ionic Liquids in Electrospray Propulsion
. Lozano June 2010 SSL # 6-10 #12;#12;Molecular Dynamics Modeling of Ionic Liquids in Electrospray Propulsion Nanako Takahashi, Paulo C. Lozano June 2010 SSL # 6-10 This work is based on the unaltered text
Modeling and control of undesirable dynamics in atomic force microscopes
El Rifai, Osamah M
2002-01-01T23:59:59.000Z
The phenomenal resolution and versatility of the atomic force microscope (AFM), has made it a widely-used instrument in nanotechnology. In this thesis, a detailed model of AFM dynamics has been developed. It includes a new ...
Models of dynamic RNA regulation in mammalian cells
Rabani, Michal
2013-01-01T23:59:59.000Z
Complex molecular circuits, consisting of multiple intertwined feedback loops and non-linear interactions, are a hallmark of every living cell, and a model of a dynamic complex network. Here, I systematically study the ...
Dynamic Modelling and Control Design of Pre-combustion Power
Foss, Bjarne A.
- pressors, gas and steam turbines and a heat recovery system. Analysis of dynamic models at an early stage principles. The pre- combustion gas power cycle plants consist of reformers and separation units, com
Applications of axial and radial compressor dynamic system modeling
Spakovszky, Zoltn S. (Zoltn Sndor), 1972-
2001-01-01T23:59:59.000Z
The presented work is a compilation of four different projects related to axial and centrifugal compression systems. The projects are related by the underlying dynamic system modeling approach that is common in all of them. ...
Model reduction for nonlinear dynamical systems with parametric uncertainties
Zhou, Yuxiang Beckett
2012-01-01T23:59:59.000Z
Nonlinear dynamical systems are known to be sensitive to input parameters. In this thesis, we apply model order reduction to an important class of such systems -- one which exhibits limit cycle oscillations (LCOs) and ...
COMPUTATIONAL FLUID DYNAMICS MODELING OF SOLID OXIDE FUEL CELLS
COMPUTATIONAL FLUID DYNAMICS MODELING OF SOLID OXIDE FUEL CELLS Ugur Pasaogullari and Chao-dimensional model has been developed to simulate solid oxide fuel cells (SOFC). The model fully couples current density operation. INTRODUCTION Solid oxide fuel cells (SOFC) are among possible candidates
Modeling exchange rate dependence dynamics at different time horizons
Embrechts, Paul
, Copula-GARCH, Conditional dependence, Dynamic copula Corresponding author. Tel.: +44(0) 247 657 4297. Financial time-series are often modeled with GARCH type models. In the multivariate GARCH literature there exist several models, like CCC- GARCH, DVEC, matrix-diagonal GARCH, BEKK and principal components GARCH
RESEARCH ARTICLE Modelling multi-species response to landscape dynamics
Kleyer, Michael
and to the spatio-temporal configuration of urban brownfield habitats in a multi-species approach (37 plant and 43- sion time of brownfield habitats required to support all and especially regionally rare species Dynamic landscape Á Species distribution model Á Habitat model Á Urban brownfields Á Model averaging Á
A Diffusion Model in Population Genetics with Mutation and Dynamic
O'Leary, Michael
A Diffusion Model in Population Genetics with Mutation and Dynamic Fitness Mike O'Leary Department of Mathematics Towson University May 24, 2008 Mike O'Leary (Towson University) A Diffusion Model in Genetics May Miller, Georgetown University Mike O'Leary (Towson University) A Diffusion Model in Genetics May 24, 2008
Lemmen, Carsten
2011-01-01T23:59:59.000Z
In the many transitions from foraging to agropastoralism it is debated whether innovation in technology or increase of population is the primary driver. The driver discussion traditionally separates Malthusian (technology driven) from Boserupian (population driven) theories. I present a numerical model of the transition to agriculture and discuss this model in the light of the population versus technology debate and in Boserup's analytical frame- work in development theory. Although my model is based on ecological-Neomalthusian- principles, the coevolutionary positive feedback relationship between technology and population results in apparent Boserupian behaviour: innovation is greatest when population pressure is highest. This outcome is not only visible in the theory-driven reduced model, but is also present in a corresponding "real world" simulator which was tested against archaeological data, and which thus demonstrates the relevance and validity of the coevolutionary model. The lesson to be learned is th...
Strongly anisotropic non-equilibrium phase transition in Ising models with friction
Sebastian Angst; Alfred Hucht; Dietrich E. Wolf
2012-05-22T23:59:59.000Z
The non-equilibrium phase transition in driven two-dimensional Ising models with two different geometries is investigated using Monte Carlo methods as well as analytical calculations. The models show dissipation through fluctuation induced friction near the critical point. We first consider high driving velocities and demonstrate that both systems are in the same universality class and undergo a strongly anisotropic non-equilibrium phase transition, with anisotropy exponent \\theta=3. Within a field theoretical ansatz the simulation results are confirmed. The crossover from Ising to mean field behavior in dependency of system size and driving velocity is analyzed using crossover scaling. It turns out that for all finite velocities the phase transition becomes strongly anisotropic in the thermodynamic limit.
A Model of Curvature-Induced Phase Transitions in Inflationary Universe
J. Hashida; S. Mukaigawa; T. Muta; K. Ohkura; K. Yamamoto
1998-12-21T23:59:59.000Z
Chiral phase transitions driven by space-time curvature effects are investigated in de Sitter space in the supersymmetric Nambu-Jona-Lasinio model with soft supersymmetry breaking. The model is considered to be suitable for the analysis of possible phase transitions in inflationary universe. It is found that a restoration of the broken chiral symmetry takes place in two patterns for increasing curvature : the first order and second order phase transition respectively depending on initial settings of the four-body interaction parameter and the soft supersymmetry breaking parameter. The critical curves expressing the phase boundaries in these parameters are obtained. Cosmological implications of the result are discussed in connection with bubble formations and the creation of cosmic strings during the inflationary era.
Phase transition in the spanning-hyperforest model on complete hypergraphs
Bedini, Andrea; Sportiello, Andrea
2009-01-01T23:59:59.000Z
By using our novel Grassmann formulation we study the phase transition of the spanning-hyperforest model of the k-uniform complete hypergraph for any k>= 2. The case k=2 reduces to the spanning-forest model on the complete graph. Different k are studied at once by using a microcanonical ensemble in which the number of hyperforests is fixed. The low-temperature phase is characterized by the appearance of a giant hyperforest. The phase transition occurs when the number of hyperforests is a fraction (k-1)/k of the total number of vertices. The behaviour at criticality is also studied by means of the coalescence of two saddle points. As the Grassmann formulation exhibits a global supersymmetry we show that the phase transition is second order and is associated to supersymmetry breaking and we explore the pure thermodynamical phase at low temperature by introducing an explicit breaking field.
Phase transition in the spanning-hyperforest model on complete hypergraphs
Andrea Bedini; Sergio Caracciolo; Andrea Sportiello
2009-06-24T23:59:59.000Z
By using our novel Grassmann formulation we study the phase transition of the spanning-hyperforest model of the k-uniform complete hypergraph for any k>= 2. The case k=2 reduces to the spanning-forest model on the complete graph. Different k are studied at once by using a microcanonical ensemble in which the number of hyperforests is fixed. The low-temperature phase is characterized by the appearance of a giant hyperforest. The phase transition occurs when the number of hyperforests is a fraction (k-1)/k of the total number of vertices. The behaviour at criticality is also studied by means of the coalescence of two saddle points. As the Grassmann formulation exhibits a global supersymmetry we show that the phase transition is second order and is associated to supersymmetry breaking and we explore the pure thermodynamical phase at low temperature by introducing an explicit breaking field.
Developing Generic Dynamic Models for the 2030 Eastern Interconnection Grid
Kou, Gefei [ORNL; Hadley, Stanton W [ORNL; Markham, Penn N [ORNL; Liu, Yilu [ORNL
2013-12-01T23:59:59.000Z
The Eastern Interconnection Planning Collaborative (EIPC) has built three major power flow cases for the 2030 Eastern Interconnection (EI) based on various levels of energy/environmental policy conditions, technology advances, and load growth. Using the power flow cases, this report documents the process of developing the generic 2030 dynamic models using typical dynamic parameters. The constructed model was validated indirectly using the synchronized phasor measurements by removing the wind generation temporarily.
A new single-dynamical-scalar-field model of dark energy
Chao-Guang Huang; Han-Ying Guo
2005-08-06T23:59:59.000Z
A new single-dynamical-scalar-field model of dark energy is proposed, in which either higher derivative terms nor structures of extra dimension are needed. With the help of a fixed background vector field, the parameter for the effective equation of state of dark energy may cross $w=-1$ in the evolution of the universe. After suitable choice of the potential, the crossing $w=-1$ and transition from decelerating to accelerating occur at $z\\approx 0.2$ and $z\\approx 1.7$, respectively.
Dynamic reactor modeling with applications to SPR and ZEDNA.
Suo-Anttila, Ahti Jorma
2011-12-01T23:59:59.000Z
A dynamic reactor model has been developed for pulse-type reactor applications. The model predicts reactor power, axial and radial fuel expansion, prompt and delayed neutron population, and prompt and delayed gamma population. All model predictions are made as a function of time. The model includes the reactivity effect of fuel expansion on a dynamic timescale as a feedback mechanism for reactor power. All inputs to the model are calculated from first principles, either directly by solving systems of equations, or indirectly from Monte Carlo N-Particle Transport Code (MCNP) derived results. The model does not include any empirical parameters that can be adjusted to match experimental data. Comparisons of model predictions to actual Sandia Pulse Reactor SPR-III pulses show very good agreement for a full range of pulse magnitudes. The model is also applied to Z-pinch externally driven neutron assembly (ZEDNA) type reactor designs to model both normal and off-normal ZEDNA operations.
ERCOT's Dynamic Model of Wind Turbine Generators: Preprint
Muljadi, E.; Butterfield, C. P.; Conto, J.; Donoho, K.
2005-08-01T23:59:59.000Z
By the end of 2003, the total installed wind farm capacity in the Electric Reliability Council of Texas (ERCOT) system was approximately 1 gigawatt (GW) and the total in the United States was about 5 GW. As the number of wind turbines installed throughout the United States increases, there is a greater need for dynamic wind turbine generator models that can properly model entire power systems for different types of analysis. This paper describes the ERCOT dynamic models and simulations of a simple network with different types of wind turbine models currently available.
Finite-temperature order-disorder phase transition in a cluster model of decagonal tilings
Ghler, Franz
phase,2 because its phason degrees of freedom are frozen (locked). The high-temperature state is accordingly called unlocked phase. Here, the thermal energy is suffi- ciently high to excite the phasonFinite-temperature order-disorder phase transition in a cluster model of decagonal tilings Michael
Finitetemperature orderdisorder phase transition in a cluster model of decagonal tilings
Ghler, Franz
the locked phase, 2 because its phason degrees of freedom are frozen (locked). The hightemperature state is accordingly called unlocked phase. Here, the thermal energy is su# ciently high to excite the phason degreesFinitetemperature orderdisorder phase transition in a cluster model of decagonal tilings Michael
On a phase field model for solid-liquid phase transitions
distinct phases. This is the case for solid-liquid mix- tures (e.g. ice-water or alloys duringOn a phase field model for solid-liquid phase transitions S. Benzoni-Gavage , L. Chupin , D. Jamet 3.2 Back to physical variables . . . . . . . . . . . . . . . . . . . . 16 4 Well-posedness 17 4
Detailed Chemical Kinetic Modeling of Iso-octane SI-HCCI Transition
Havstad, Mark A [Lawrence Livermore National Laboratory (LLNL); Aceves, Salvador M [Lawrence Livermore National Laboratory (LLNL); McNenly, Matthew J [Lawrence Livermore National Laboratory (LLNL); Piggott, William T [Lawrence Livermore National Laboratory (LLNL); Edwards, Kevin Dean [ORNL; Wagner, Robert M [ORNL; Daw, C Stuart [ORNL; FINNEY, Charles E A [ORNL
2010-01-01T23:59:59.000Z
We describe a CHEMKIN-based multi-zone model that simulates the expected combustion variations in a single-cylinder engine fueled with iso-octane as the engine transitions from spark-ignited (SI) combustion to homogenous charge compression ignition (HCCI) combustion. The model includes a 63-species reaction mechanism and mass and energy balances for the cylinder and the exhaust flow. For this study we assumed that the SI-to-HCCI transition is implemented by means of increasing the internal exhaust gas recirculation (EGR) at constant engine speed. This transition scenario is consistent with that implemented in previously reported experimental measurements on an experimental engine equipped with variable valve actuation. We find that the model captures many of the important experimental trends, including stable SI combustion at low EGR (-0.10), a transition to highly unstable combustion at intermediate EGR, and finally stable HCCI combustion at very high EGR (-0.75). Remaining differences between the predicted and experimental instability patterns indicate that there is further room for model improvement.
DETAILED CHEMICAL KINETIC MODELING OF ISO-OCTANE SI-HCCI TRANSITION
Havstad, M A; Aceves, S M; McNenly, M J; Piggott, W T; Edwards, K D; Wagner, R M; Daw, C S; Finney, C A
2009-10-12T23:59:59.000Z
The authors describe a CHEMKIN-based multi-zone model that simulates the expected combustion variations in a single-cylinder engine fueled with iso-octane as the engine transitions from spark-ignited (ST) combustion to homogeneous charge compression ignition (HCCI) combustion. The model includes a 63-species reaction mechanism and mass and energy balances for the cylinder and the exhaust flow. For this study they assumed that the SI-to-HCCI transition is implemented by means of increasing the internal exhaust gas recirculation (EGR) at constant engine speed. This transition scneario is consistent with that implemented in previously reported experimental measurements on an experimental engine equipped with variable valve actuation. They find that the model captures many of the important experimental trends, including stable SI combustion at low EGR ({approx} 0.10), a transition to highly unstable combustion at intermediate EGR, and finally stable HCCI combustion at very high EGR ({approx} 0.75). Remaining differences between the predicted and experimental instability patterns indicate that there is further room for model improvement.
Dynamic competition model for construction contractors
Kim, Hyung Jin
2004-01-01T23:59:59.000Z
as an entity in a dynamic system, in which every entity is a profit optimizer responding to market conditions as well as its competitors' actions. In construction, the issue of competition has been focused on competitive bidding, which is a critical mechanism...
Human Muscle Fatigue Model in Dynamic Motions
Boyer, Edmond
into account. In this paper, each human joint is assumed to be controlled by two muscle groups to generate on motor units pattern. They demonstrated the relationship among muscle activation, fatigue and recovery fatigue trend in static working posture (elbow = 90 , shoulder = 30 ), but in dynamic working situation
Dynamic competition model for construction contractors
Kim, Hyung Jin
2004-01-01T23:59:59.000Z
as an entity in a dynamic system, in which every entity is a profit optimizer responding to market conditions as well as its competitors' actions. In construction, the issue of competition has been focused on competitive bidding, which is a critical mechanism...
Truong, Thanh N.
of a focusing technique to minimize the number of electronic structure calculations, while still preservingA direct ab inifio dynamics approach for calculating thermal rate constants using variational dynamics, " for calculations of thermal rate constants and related properties from first principles
Ford, Eric B. [Astronomy Department, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32111 (United States); Ragozzine, Darin; Holman, Matthew J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rowe, Jason F.; Barclay, Thomas; Borucki, William J.; Bryson, Stephen T.; Caldwell, Douglas A.; Kinemuchi, Karen; Koch, David G.; Lissauer, Jack J.; Still, Martin; Tenenbaum, Peter [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Steffen, Jason H. [Fermilab Center for Particle Astrophysics, P.O. Box 500, MS 127, Batavia, IL 60510 (United States); Batalha, Natalie M. [Department of Physics and Astronomy, San Jose State University, San Jose, CA 95192 (United States); Fabrycky, Daniel C. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Gautier, Thomas N. [Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States); Ibrahim, Khadeejah A.; Uddin, Kamal [Orbital Sciences Corporation/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Kjeldsen, Hans, E-mail: eford@astro.ufl.edu [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); and others
2012-09-10T23:59:59.000Z
Transit timing variations provide a powerful tool for confirming and characterizing transiting planets, as well as detecting non-transiting planets. We report the results of an updated transit timing variation (TTV) analysis for 1481 planet candidates based on transit times measured during the first sixteen months of Kepler observations. We present 39 strong TTV candidates based on long-term trends (2.8% of suitable data sets). We present another 136 weaker TTV candidates (9.8% of suitable data sets) based on the excess scatter of TTV measurements about a linear ephemeris. We anticipate that several of these planet candidates could be confirmed and perhaps characterized with more detailed TTV analyses using publicly available Kepler observations. For many others, Kepler has observed a long-term TTV trend, but an extended Kepler mission will be required to characterize the system via TTVs. We find that the occurrence rate of planet candidates that show TTVs is significantly increased ({approx}68%) for planet candidates transiting stars with multiple transiting planet candidates when compared to planet candidates transiting stars with a single transiting planet candidate.
Huse, N.; Kim, T.-K.; Khalil, M.; Jamula, L.; McCusker, J.K.; Schoenlein, R.W.
2008-08-01T23:59:59.000Z
We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding. We report the first time-resolved soft x-ray spectroscopy of solution-phase molecular dynamics. Changes in ligand-field splitting and spin-state populations in 3d orbitals of the Fe{sup II} complex are directly probed via transient absorption changes of the Fe L{sub 2} and L{sub 3} edges following photo-induced metal-to-ligand charge transfer. With the emergence of high-flux ultrafast soft x-ray sources, details on interplay between atomic structure, electronic states, and spin contributions will be revealed. Our experimental approach opens the door to femtosecond soft x-ray investigations of liquid phase chemistry that have previously been inaccessible.
A thermodynamically consistent Ginzburg-Landau model for superfluid transition in liquid helium
Alessia Berti; Valeria Berti
2012-11-15T23:59:59.000Z
In this paper we propose a thermodynamically consistent model for superfluid-normal phase transition in liquid helium, accounting for variations of temperature and density. The phase transition is described by means of an order parameter, according to the Ginzburg-Landau theory, emphasizing the analogies between superfluidity and superconductivity. The normal component of the velocity is assumed to be compressible and the usual phase diagram of liquid helium is recovered. Moreover, the continuity equation leads to a dependence between density and temperature in agreement with the experimental data.
Structure formation: Models, Dynamics and Status
T. Padmanabhan
1995-08-25T23:59:59.000Z
The constraints on the models for the structure formation arising from various cosmological observations at different length scales are reviewed. The status of different models for structure formation is examined critically in the light of these observations.
A Dynamic Model with Import Quota Constraints
Basak, Suleyman
2004-07-09T23:59:59.000Z
The analysis of import quotas is predominantly based on a static model, which is unable to capture the fact that a quota is imposed over a period of time. This article develops a continuous-time model ...
Dynamics of geometric phase in the adiabatic limit of quantum phase transition
B. Basu
2010-05-10T23:59:59.000Z
The geometric phase associated with a many body ground state exhibits a signature of quantum phase transition. In this context, we have studied the behaviour of the geometric phase during a linear quench caused by a gradual turning off of the magnetic field interacting with a spin chain.
Dynamical hierarchy in transition states: Why and how does a system climb over the mountain?
Berry, R. Stephen
University, Nada, Kobe 657-8501, Japan; and Department of Chemistry and the James Franck Institute Institute of Technology, Pasadena, CA, and approved April 12, 2001 (received for review December 28, 2000 to visualize the stable and unstable invariant manifolds leading to and from the transition state, i
Sandborn, Peter
Proceedings of the 2007 Aging Aircraft Conference Cost Model for Assessing the Transition to Lead the cost ramifications of the transition from tin- lead to lead-free electronic parts. All tin-lead, all lead-free and mixed assembly approaches are considered. The model makes basic assumptions of a fixed
Phase transitions in self-gravitating systems. Self-gravitating fermions and hard spheres models
P. H. Chavanis
2002-01-28T23:59:59.000Z
We discuss the nature of phase transitions in self-gravitating systems both in the microcanonical and in the canonical ensemble. We avoid the divergence of the gravitational potential at short distances by considering the case of self-gravitating fermions and hard spheres models. Three kinds of phase transitions (of zeroth, first and second order) are evidenced. They separate a ``gaseous'' phase with a smoothly varying distribution of matter from a ``condensed'' phase with a core-halo structure. We propose a simple analytical model to describe these phase transitions. We determine the value of energy (in the microcanonical ensemble) and temperature (in the canonical ensemble) at the transition point and we study their dependance with the degeneracy parameter (for fermions) or with the size of the particles (for a hard spheres gas). Scaling laws are obtained analytically in the asymptotic limit of a small short distance cut-off. Our analytical model captures the essential physics of the problem and compares remarkably well with the full numerical solutions.
Zhu, Lin; Gong, Huili; Gable, Carl; Teatini, Pietro
2015-01-01T23:59:59.000Z
Understanding the heterogeneity arising from the complex architecture of sedimentary sequences in alluvial fans is challenging. This paper develops a statistical inverse framework in a multi-zone transition probability approach for characterizing the heterogeneity in alluvial fans. An analytical solution of the transition probability matrix is used to define the statistical relationships among different hydrofacies and their mean lengths, integral scales, and volumetric proportions. A statistical inversion is conducted to identify the multi-zone transition probability models and estimate the optimal statistical parameters using the modified Gauss-Newton-Levenberg-Marquardt method. The Jacobian matrix is computed by the sensitivity equation method, which results in an accurate inverse solution with quantification of parameter uncertainty. We use the Chaobai River alluvial fan in the Beijing Plain, China, as an example for elucidating the methodology of alluvial fan characterization. The alluvial fan is divided...
Assessing the reliability of linear dynamic transformer thermal modelling
Assessing the reliability of linear dynamic transformer thermal modelling X. Mao, D.J. Tylavsky and G.A. McCulla Abstract: Improving the utilisation of transformers requires that the hot-spot and top. An alternative method for assessing transformer model reliability is provided. 1 Introduction The maximally
Long-wave models of thin film fluid dynamics
A. J. Roberts
1994-11-04T23:59:59.000Z
Centre manifold techniques are used to derive rationally a description of the dynamics of thin films of fluid. The derived model is based on the free-surface $\\eta(x,t)$ and the vertically averaged horizontal velocity $\\avu(x,t)$. The approach appears to converge well and has significant differences from conventional depth-averaged models.
Modeling Lake Erie ice dynamics: Process studies , Haoguo Hu2
Modeling Lake Erie ice dynamics: Process studies Jia Wang1 , Haoguo Hu2 , and Xuezhi Bai2 1 NOAA of Michigan 4840 S. State Road, Ann Arbor, MI 48108 Abstract. A Great Lakes Ice-circulation Model (GLIM derived from meteorological measurements. After the seasonal cycles of ice concentration, thickness
Title of dissertation: MODELING, SIMULATING, AND CONTROLLING THE FLUID DYNAMICS
Shapiro, Benjamin
ABSTRACT Title of dissertation: MODELING, SIMULATING, AND CONTROLLING THE FLUID DYNAMICS OF ELECTRO an algorithm to steer indi- vidual particles inside the EWOD system by control of actuators already present number of actuators available in the EWOD system. #12;MODELING, SIMULATING, AND CONTROLLING THE FLUID
Controlling Social Dynamics with a Parametrized Model of Floor Regulation
Das, Suman
Controlling Social Dynamics with a Parametrized Model of Floor Regulation Crystal Chao, Andrea L is to build autonomous robot controllers for successfully engaging in human-like turn-taking interactions. Towards this end, we present CADENCE, a novel computational model and architecture that explicitly reasons
Model Reduction Near Periodic Orbits of Hybrid Dynamical Systems
Sastry, S. Shankar
manipulation in manufacturing [2], gene regulation in cells [3], and power generation in electrical systems [41 Model Reduction Near Periodic Orbits of Hybrid Dynamical Systems Samuel A. Burden, Shai Revzen system. We demonstrate reduction of a highdimensional underactuated mechanical model for terrestrial
Numerical Modeling of Brain Dynamics in Traumatic Situations -Impulsive Translations
Burtscher, Martin
.S.A. Abstract We numerically model the brain dy- namics during and after impulsive head translations using brain injuries appear among boxers and shaken babies despite minimal rotations of their heads. Modeling head translations also helps understand the brain dynamics during head rotations about an arbitrary
Numerically Estimating Internal Models of Dynamic Virtual Objects
Sekuler, Robert
human subjects to manipulate a computer-animated virtual object. This virtual object (vO) was a high, human cognition, human information processing, ideal performer, internal model, virtual object, virtual, specifically how humans acquire an internal model of a dynamic virtual object. Our methodology minimizes
Thermodiffusion in model nanofluids by molecular dynamics simulations
Paris-Sud XI, Universit de
1 Thermodiffusion in model nanofluids by molecular dynamics simulations G. Galliero1,2,* , S. Volz3-Jones fluids and for model nanofluids (spherical non-metallic nanoparticles + Lennard-Jones fluid) where concentration. Then, in nanofluids in the liquid state, by changing the nature of the nanoparticle (size, mass
Passive dynamic walking with knees : a point foot model
Hsu Chen, Vanessa F. (Vanessa Fang)
2007-01-01T23:59:59.000Z
In this thesis, a hybrid model for a passive 2D walker with knees and point feet is presented. The step cycle of the model has two phases of continuous dynamics: one with an unlocked knee configuration and a second one ...
Variational Inference in Stochastic Dynamic Environmental Models Dan Cornford1
Roulstone, Ian
Variational Inference in Stochastic Dynamic Environmental Models Dan Cornford1 , Manfred Opper2 number of degrees of freedom. Environmental forecasting centres have taken strategic decisions to develop on related phenomena, such as flooding and storm damage, and on the spread of pollutants. The models needed
Dynamics of many-body localisation in a translation invariant quantum glass model
Merlijn van Horssen; Emanuele Levi; Juan P. Garrahan
2015-05-26T23:59:59.000Z
We study the real-time dynamics of a translationally invariant quantum spin chain, based on the East kinetically constrained glass model, in search for evidence of many-body localisation in the absence of disorder. Numerical simulations indicate a change, controlled by a coupling parameter, from a regime of fast relaxation---corresponding to thermalisation---to a regime of very slow relaxation. This slowly relaxing regime is characterised by dynamical features usually associated with non-ergodicity and many-body localisation (MBL): memory of initial conditions, logarithmic growth of entanglement entropy, and non-exponential decay of time-correlators. We show that slow relaxation is a consequence of sensitivity to spatial fluctuations in the initial state. While numerics indicate that certain relaxation timescales grow markedly with size, our finite size results are consistent both with an MBL transition, expected to only occur in disordered systems, or with a pronounced quasi-MBL crossover.
Exact results for the criticality of quench dynamics in quantum Ising models
Ying Li; M. X. Huo; Z. Song
2009-06-23T23:59:59.000Z
Based on the obtained exact results we systematically study the quench dynamics of a one-dimensional spin-1/2 transverse field Ising model with zero- and finite-temperature initial states. We focus on the magnetization of the system after a sudden change of the external field and a coherent time-evolution process. With a zero-temperature initial state, the quench magnetic susceptibility as a function of the initial field strength exhibits strongly similar scaling behaviors to those of the static magnetic susceptibility, and the quench magnetic susceptibility as a function of the final field strength shows a discontinuity at the quantum critical point. This discontinuity remains robust and always occurs at the quantum critical point even for the case of finite-temperature initial systems, which indicates a great advantage of employing quench dynamics to study quantum phase transitions.
Modeling and simulation of consumer response to dynamic pricing.
Valenzuela, J.; Thimmapuram, P.; Kim, J (Decision and Information Sciences); (Auburn Univ.)
2012-08-01T23:59:59.000Z
Assessing the impacts of dynamic-pricing under the smart grid concept is becoming extremely important for deciding its full deployment. In this paper, we develop a model that represents the response of consumers to dynamic pricing. In the model, consumers use forecasted day-ahead prices to shift daily energy consumption from hours when the price is expected to be high to hours when the price is expected to be low while maintaining the total energy consumption as unchanged. We integrate the consumer response model into the Electricity Market Complex Adaptive System (EMCAS). EMCAS is an agent-based model that simulates restructured electricity markets. We explore the impacts of dynamic-pricing on price spikes, peak demand, consumer energy bills, power supplier profits, and congestion costs. A simulation of an 11-node test network that includes eight generation companies and five aggregated consumers is performed for a period of 1 month. In addition, we simulate the Korean power system.
QCD Phase Transition in Brans-Dicke DGP model of Brane Gravity
T. Golanbari; A. Mohammadi; Kh. Saaidi
2014-08-24T23:59:59.000Z
A DGP brane-world model with a perfect fluid brane matter including a Brans-Dicke (BD) scalar field on brane has been utilized to investigate the problem of quark-hadron phase (QHP) transition in early times of the Universe evoltion. The presence of BD scalar field came up with some modification terms in the Friedmann equation, however we have a usual form of conservation equation for brane matter since scalar field only has a non-mnimally interaction with geometry. Behavior of phase transition strongly depends on the basic evolution equations. Then, even a small change in these relation might come to interesting results about the time of transition. Two different formalisms as smooth crossover formalism in which lattice QCD data is used for obtaining the matter equation of state and first-order phase transition formalism, have been used to investigate of the evolution of physical quatities relevant to quantitative of early times such as energy density $\\rho$, scale factor $a$, and temperature $T$. The obtained results show that the general behavior of temperature is similar in both of two formalisms and the QHP transition occurred at about micro-second after the Big Bang.
North, Simon W.
A Two Transition State Model for Radical-Molecule Reactions: A Case Study of the Addition of OH; In Final Form: April 6, 2005 A two transition state model is applied to the study of the addition of both inner and outer transition states. The outer transition state is treated with a recently derived
Modeling Space-Time Dynamics of Aerosols Using Satellite Data and Atmospheric Transport Model Output
Shi, Tao
Modeling Space-Time Dynamics of Aerosols Using Satellite Data and Atmospheric Transport Model of aerosol optical depth across mainland Southeast Asia. We include a cross validation study to assess
Stuart, J.G.; Wright, A.D.; Butterfield, C.P.
1996-10-01T23:59:59.000Z
Mitigating the effects of damaging wind turbine loads and responses extends the lifetime of the turbine and, consequently, reduces the associated Cost of Energy (COE). Active control of aerodynamic devices is one option for achieving wind turbine load mitigation. Generally speaking, control system design and analysis requires a reasonable dynamic model of {open_quotes}plant,{close_quotes} (i.e., the system being controlled). This paper extends the wind turbine aileron control research, previously conducted at the National Wind Technology Center (NWTC), by presenting a more detailed development of the wind turbine dynamic model. In prior research, active aileron control designs were implemented in an existing wind turbine structural dynamics code, FAST (Fatigue, Aerodynamics, Structures, and Turbulence). In this paper, the FAST code is used, in conjunction with system identification, to generate a wind turbine dynamic model for use in active aileron control system design. The FAST code is described and an overview of the system identification technique is presented. An aileron control case study is used to demonstrate this modeling technique. The results of the case study are then used to propose ideas for generalizing this technique for creating dynamic models for other wind turbine control applications.
Weeks, Eric R.
this behavior. The mode coupling theory [1] describes many aspects of dynamical behavior at high T- stood as a simple activated bondbreaking process. Here, we perform molecular dynamics (MD) simula- tionsSpatially Heterogeneous Dynamics and Dynamic Facilitation in a Model of Viscous Silica Michael
Symmetry induced Dynamics in four-dimensional Models deriving from the van der Pol Equation
Ricardo Lopez-Ruiz
2003-09-04T23:59:59.000Z
Different models of self-excited oscillators which are four-dimensional extensions of the van der Pol system are reported. Their symmetries are analyzed. Three of them were introduced to model the release of vortices behind circular cylinders with a possible transition from a symmetric to an antisymmetric Benard-von Karman vortex street. The fourth reported self-excited oscillator is a new model which implements the breaking of the inversion symmetry. It presents the phenomenon of second harmonic generation in a natural way. The parallelism with second harmonic generation in nonlinear optics is discussed. There is also a small region in the parameter space where the dynamics of this system is quasiperiodic or chaotic.
Friction in a Model of Hamiltonian Dynamics
Juerg Froehlich; Zhou Gang; Avy Soffer
2011-11-01T23:59:59.000Z
We study the motion of a heavy tracer particle weakly coupled to a dense ideal Bose gas exhibiting Bose-Einstein condensation. In the so-called mean-field limit, the dynamics of this system approaches one determined by nonlinear Hamiltonian evolution equations describing a process of emission of Cerenkov radiation of sound waves into the Bose-Einstein condensate along the particle's trajectory. The emission of Cerenkov radiation results in a friction force with memory acting on the tracer particle and causing it to decelerate until it comes to rest.
DYNAMICAL MODEL OF AN EXPANDING SHELL
Pe'er, Asaf [Harvard-Smithsonian Center for Astrophysics, MS-51, 60 Garden Street, Cambridge, MA 02138 (United States)
2012-06-10T23:59:59.000Z
Expanding blast waves are ubiquitous in many astronomical sources, such as supernova remnants, X-ray emitting binaries, and gamma-ray bursts. I consider here the dynamics of such an expanding blast wave, both in the adiabatic and the radiative regimes. As the blast wave collects material from its surroundings, it decelerates. A full description of the temporal evolution of the blast wave requires consideration of both the energy density and the pressure of the shocked material. The obtained equation is different from earlier works in which only the energy was considered. The solution converges to the familiar results in both the ultrarelativistic and the sub-relativistic (Newtonian) regimes.
A model of lipid-free Apolipoprotein A-I revealed by iterative molecular dynamics simulation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhang, Xing; Lei, Dongsheng; Zhang, Lei; Rames, Matthew; Zhang, Shengli
2015-03-20T23:59:59.000Z
Apolipoprotein A-I (apo A-I), the major protein component of high-density lipoprotein, has been proven inversely correlated to cardiovascular risk in past decades. The lipid-free state of apo A-I is the initial stage which binds to lipids forming high-density lipoprotein. Molecular models of lipid-free apo A-I have been reported by methods like X-ray crystallography and chemical cross-linking/mass spectrometry (CCL/MS). Through structural analysis we found that those current models had limited consistency with other experimental results, such as those from hydrogen exchange with mass spectrometry. Through molecular dynamics simulations, we also found those models could not reach a stable equilibrium state. Therefore,moreby integrating various experimental results, we proposed a new structural model for lipidfree apo A-I, which contains a bundled four-helix N-terminal domain (1192) that forms a variable hydrophobic groove and a mobile short hairpin C-terminal domain (193243). This model exhibits an equilibrium state through molecular dynamics simulation and is consistent with most of the experimental results known from CCL/MS on lysine pairs, fluorescence resonance energy transfer and hydrogen exchange. This solution-state lipid-free apo A-I model may elucidate the possible conformational transitions of apo A-I binding with lipids in high-density lipoprotein formation.less
A dynamic model of industrial energy demand in Kenya
Haji, S.H.H. [Gothenburg Univ. (Sweden)
1994-12-31T23:59:59.000Z
This paper analyses the effects of input price movements, technology changes, capacity utilization and dynamic mechanisms on energy demand structures in the Kenyan industry. This is done with the help of a variant of the second generation dynamic factor demand (econometric) model. This interrelated disequilibrium dynamic input demand econometric model is based on a long-term cost function representing production function possibilities and takes into account the asymmetry between variable inputs (electricity, other-fuels and Tabour) and quasi-fixed input (capital) by imposing restrictions on the adjustment process. Variations in capacity utilization and slow substitution process invoked by the relative input price movement justifies the nature of input demand disequilibrium. The model is estimated on two ISIS digit Kenyan industry time series data (1961 - 1988) using the Iterative Zellner generalized least square method. 31 refs., 8 tabs.
Modeling Infection with Multi-agent Dynamics
Dong, Wen
2012-01-01T23:59:59.000Z
Developing the ability to comprehensively study infections in small populations enables us to improve epidemic models and better advise individuals about potential risks to their health. We currently have a limited ...
Modeling of Alpine Atmospheric Dynamics II
Gohm, Alexander
: mesoscale convective system 17-18 April 2004: Sierra hydraulic jump case 21 January 2005: the "Universiade) Results and discussion (synoptic scale overview, mesoscale structure, comparison of model and measurements
Generative modeling of dynamic visual scenes
Lin, Dahua, Ph. D. Massachusetts Institute of Technology
2012-01-01T23:59:59.000Z
Modeling visual scenes is one of the fundamental tasks of computer vision. Whereas tremendous efforts have been devoted to video analysis in past decades, most prior work focuses on specific tasks, leading to dedicated ...
Modeling emotion dynamics in intelligent agents
Seif El-Nasr, Magy
1998-01-01T23:59:59.000Z
OF SIMULATION AND RESULTS . . . . . . . . . . . D. CONTRIBUTIONS 7. STRUCTURE OF THE THESIS 1 3 4 7 9 13 13 15 18 18 19 11 PREVIOUS WORK . . 20 1. PSYCHOLOGICAL MODELS . A. MOTIVATIONAL STATES . B. APPRAISAL MODELS OF EMOTIONS... all the needs and urges, while the mind is the heart of the rational thinking process [9]. After three centuries, new theories of emotions were established. By 1884, William James [15] published his article "What is Emotion?" At that time...
Greene, David L [ORNL
2007-02-01T23:59:59.000Z
The global energy system faces sweeping changes in the next few decades, with potentially critical implications for the global economy and the global environment. It is important that global institutions have the tools necessary to predict, analyze and plan for such massive change. This report summarizes the proceedings of an international workshop concerning methods of forecasting, analyzing, and planning for global energy transitions and their economic and environmental consequences. A specific case, it focused on the transition from conventional to unconventional oil and other energy sources likely to result from a peak in non-OPEC and/or global production of conventional oil. Leading energy models from around the world in government, academia and the private sector met, reviewed the state-of-the-art of global energy modeling and evaluated its ability to analyze and predict large-scale energy transitions.
Models of Receptive Field Dynamics in Visual Cortex
1999-01-01T23:59:59.000Z
The position, size, and shape of the receptive field (RF) of some cortical neurons change dynamically, in response to artificial scotoma conditioning (Pettet & Gilbert, 1992) and to retinal lesions (Chino et al., 1992; Darian-Smith & Gilbert, 1995) in adult animals. The RF dynamics are of interest because they show how visual systems may adaptively overcome damage (from lesions, scotomas, or other failures), may enhance processing efficiency by altering RF coverage in response to visual demand, and may perform perceptual learning. This paper presents an afferent excitatory synaptic plasticity rule and a lateral inhibitory synaptic plasticity rule -- the EXIN rules (Marshall, 1995a) -- to model persistent RF changes after artificial scotoma conditioning and retinal lesions. The EXIN model is compared to the LISSOM model (Sirosh et al., 1996) and to a neuronal adaptation model (Xing & Gerstein, 1994). The rules within each model are isolated and are analyzed independently, to elucidate t...
Huse, Nils; Cho, Hana; Hong, Kiryong; Jamula, Lindsey; de Groot, Frank M. F.; Kim, Tae Kyu; McCusker, James K.; Schoenlein, Robert W.
2011-03-09T23:59:59.000Z
We present the first implementation of femtosecond soft X-ray spectroscopy as an ultrafast direct probe of the excited-state valence orbitals in solution-phase molecules. This method is applied to photoinduced spin crossover of [Fe(tren(py)3)]2+, where the ultrafast spinstate conversion of the metal ion, initiated by metal-to-ligand charge-transfer excitation, is directly measured using the intrinsic spin-state selectivity of the soft X-ray L-edge transitions. Our results provide important experimental data concerning the mechanism of ultrafast spin-state conversion and subsequent electronic and structural dynamics, highlighting the potential of this technique to study ultrafast phenomena in the solution phase.
CSAW: a dynamical model of protein folding
Kerson Huang
2006-01-12T23:59:59.000Z
CSAW (conditioned self-avoiding walk) is a model of protein folding that combines SAW (self-avoiding walk) with Monte-Carlo. It simulates the Brownian motion of a chain molecule in the presence of interactions, both among chain residues, and with the environment. In a first model that includes the hydrophobic effect and hydrogen bonding, a chain of 30 residues folds into a native state with stable secondary and tertiary structures. The process starts with a rapid collapse into an intermediate "molten globule", which slowly decays into the native state afer a relatively long quiescent period. The behavior of the radius of gyration mimics experimental data.
UNCORRECTEDPROOF Parameter identification in dynamical models of
Timmer, Jens
only biogas production rate was 14 measured which complicates the analysis considerably. We show product is methane. In recent years more and more complex mathematical models of anaerobic 26 digestion. Yet in many ex- 36 perimental settings only biogas production rate data is available which complicates
Green Algae as Model Organisms for Biological Fluid Dynamics
Goldstein, Raymond E
2014-01-01T23:59:59.000Z
In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these re...
Green Algae as Model Organisms for Biological Fluid Dynamics
Raymond E. Goldstein
2014-09-08T23:59:59.000Z
In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.
Dynamic crack initiation toughness : experiments and peridynamic modeling.
Foster, John T.
2009-10-01T23:59:59.000Z
This is a dissertation on research conducted studying the dynamic crack initiation toughness of a 4340 steel. Researchers have been conducting experimental testing of dynamic crack initiation toughness, K{sub Ic}, for many years, using many experimental techniques with vastly different trends in the results when reporting K{sub Ic} as a function of loading rate. The dissertation describes a novel experimental technique for measuring K{sub Ic} in metals using the Kolsky bar. The method borrows from improvements made in recent years in traditional Kolsky bar testing by using pulse shaping techniques to ensure a constant loading rate applied to the sample before crack initiation. Dynamic crack initiation measurements were reported on a 4340 steel at two different loading rates. The steel was shown to exhibit a rate dependence, with the recorded values of K{sub Ic} being much higher at the higher loading rate. Using the knowledge of this rate dependence as a motivation in attempting to model the fracture events, a viscoplastic constitutive model was implemented into a peridynamic computational mechanics code. Peridynamics is a newly developed theory in solid mechanics that replaces the classical partial differential equations of motion with integral-differential equations which do not require the existence of spatial derivatives in the displacement field. This allows for the straightforward modeling of unguided crack initiation and growth. To date, peridynamic implementations have used severely restricted constitutive models. This research represents the first implementation of a complex material model and its validation. After showing results comparing deformations to experimental Taylor anvil impact for the viscoplastic material model, a novel failure criterion is introduced to model the dynamic crack initiation toughness experiments. The failure model is based on an energy criterion and uses the K{sub Ic} values recorded experimentally as an input. The failure model is then validated against one class of problems showing good agreement with experimental results.
A Dynamical Model of Plasma Turbulence in the Solar Wind
Howes, G G
2015-01-01T23:59:59.000Z
A dynamical approach, rather than the usual statistical approach, is taken to explore the physical mechanisms underlying the nonlinear transfer of energy, the damping of the turbulent fluctuations, and the development of coherent structures in kinetic plasma turbulence. It is argued that the linear and nonlinear dynamics of Alfven waves are responsible, at a very fundamental level, for some of the key qualitative features of plasma turbulence that distinguish it from hydrodynamic turbulence, including the anisotropic cascade of energy and the development of current sheets at small scales. The first dynamical model of kinetic turbulence in the weakly collisional solar wind plasma that combines self-consistently the physics of Alfven waves with the development of small-scale current sheets is presented and its physical implications are discussed. This model leads to a simplified perspective on the nature of turbulence in a weakly collisional plasma: the nonlinear interactions responsible for the turbulent casca...
Model Independent Analysis of Beam Centroid Dynamics in Accelerators
Wang, Chun-xi
2003-04-21T23:59:59.000Z
Fundamental issues in Beam-Position-Monitor (BPM)-based beam dynamics observations are studied in this dissertation. The major topic is the Model-Independent Analysis (MIA) of beam centroid dynamics. Conventional beam dynamics analysis requires a certain machine model, which itself of ten needs to be refined by beam measurements. Instead of using any particular machine model, MIA relies on a statistical analysis of the vast amount of BPM data that often can be collected non-invasively during normal machine operation. There are two major parts in MIA. One is noise reduction and degrees-of-freedom analysis using a singular value decomposition of a BPM-data matrix, which constitutes a principal component analysis of BPM data. The other is a physical base decomposition of the BPM-data matrix based on the time structure of pulse-by-pulse beam and/or machine parameters. The combination of these two methods allows one to break the resolution limit set by individual BPMs and observe beam dynamics at more accurate levels. A physical base decomposition is particularly useful for understanding various beam dynamics issues. MIA improves observation and analysis of beam dynamics and thus leads to better understanding and control of beams in both linacs and rings. The statistical nature of MIA makes it potentially useful in other fields. Another important topic discussed in this dissertation is the measurement of a nonlinear Poincare section (one-turn) map in circular accelerators. The beam dynamics in a ring is intrinsically nonlinear. In fact, nonlinearities are a major factor that limits stability and influences the dynamics of halos. The Poincare section map plays a basic role in characterizing and analyzing such a periodic nonlinear system. Although many kinds of nonlinear beam dynamics experiments have been conducted, no direct measurement of a nonlinear map has been reported for a ring in normal operation mode. This dissertation analyzes various issues concerning map measurements and shows that it is possible to measure the Poincare section map (in terms of Taylor series) of a circular accelerator to a surprisingly high order and accuracy based on present BPM technology. MIA can overcome the inherent limit of BPM resolution. Nonlinear map measurements will advance understanding of the beam dynamics of a ring.
L-H transition dynamics in fluid turbulence simulations with neoclassical force balance
Chn, L. [AixMarseille Universit, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Beyer, P.; Fuhr, G.; Benkadda, S. [AixMarseille Universit, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Sarazin, Y.; Bourdelle, C. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)
2014-07-15T23:59:59.000Z
Spontaneous transport barrier generation at the edge of a magnetically confined plasma is reproduced in flux-driven three-dimensional fluid simulations of electrostatic turbulence. Here, the role on the radial electric field of collisional friction between trapped and passing particles is shown to be the key ingredient. Especially, accounting for the self-consistent and precise dependence of the friction term on the actual plasma temperature allows for the triggering of a transport barrier, provided that the input power exceeds some threshold. In addition, the barrier is found to experience quasi-periodic relaxation events, reminiscent of edge localised modes. These results put forward a possible key player, namely, neoclassical physics via radial force balance, for the low- to high-confinement regime transition observed in most of controlled fusion devices.
Wind Energy Applications of Unified and Dynamic Turbulence Models
Heinz, Stefan
Wind Energy Applications of Unified and Dynamic Turbulence Models Stefan Heinz and Harish Gopalan applicable as a low cost alternative. 1 Introduction There is a growing interest in using wind energy suggests the possibility of providing 20% of the electricity in the U.S. by wind energy in 2030
DYNAMIC MODELLING OF AUTONOMOUS POWER SYSTEMS INCLUDING RENEWABLE POWER SOURCES.
Paris-Sud XI, Université de
(thermal, gas, diesel) and renewable (hydro, wind) power units. The objective is to assess the impact - that have a special dynamic behaviour, and the wind turbines. Detailed models for each one of the power system components are developed. Emphasis is given in the representation of different hydro power plant
Non-perturbative Dynamical Decoupling Control: A Spin Chain Model
Zhao-Ming Wang; Lian-Ao Wu; Jun Jing; Bin Shao; Ting Yu
2012-03-24T23:59:59.000Z
This paper considers a spin chain model by numerically solving the exact model to explore the non-perturbative dynamical decoupling regime, where an important issue arises recently (J. Jing, L.-A. Wu, J. Q. You and T. Yu, arXiv:1202.5056.). Our study has revealed a few universal features of non-perturbative dynamical control irrespective of the types of environments and system-environment couplings. We have shown that, for the spin chain model, there is a threshold and a large pulse parameter region where the effective dynamical control can be implemented, in contrast to the perturbative decoupling schemes where the permissible parameters are represented by a point or converge to a very small subset in the large parameter region admitted by our non-perturbative approach. An important implication of the non-perturbative approach is its flexibility in implementing the dynamical control scheme in a experimental setup. Our findings have exhibited several interesting features of the non-perturbative regimes such as the chain-size independence, pulse strength upper-bound, noncontinuous valid parameter regions, etc. Furthermore, we find that our non-perturbative scheme is robust against randomness in model fabrication and time-dependent random noise.
Multiscale modeling of polystyrene dynamics in different environments
Faller, Roland
Multiscale modeling of polystyrene dynamics in different environments Qi Sun1 , Florence Pon1 simulations can address not only the average properties of the system but also the distribution over any component in their neighborhood and vice versa. The simulation temperature of 450 K is chosen to be above
Approximate Dynamic Programming for Networks: Fluid Models and Constraint Reduction
Veatch, Michael H.
of approximating functions for the differential cost. The first contribution of this paper is identifying new or piece-wise quadratic. Fluid cost has been used to initialize the value iteration algorithm [5Approximate Dynamic Programming for Networks: Fluid Models and Constraint Reduction Michael H
Model-Driven Dynamic Control of Embedded Wireless Sensor Networks
Agarwal, Pankaj K.
Model-Driven Dynamic Control of Embedded Wireless Sensor Networks Paul G. Flikkema1 , Pankaj K-generation wireless sensor networks may revolution- ize understanding of environmental change by assimilating heteroge of wireless sensor networks is now becoming a mature research field. As a result, the discipline is undergoing
Dynamical Analysis of the Fitzhugh-Nagumo Model
Beer, Randall D.
Dynamical Analysis of the Fitzhugh-Nagumo Model #12;IU/COGS-Q580/Beer This isYour Brain #12;IU/COGS-Q580/Beer Action Potentials Tateno, T., Harsch, A. and Robinson, H.P.C. (2004). Threshold Firing. Neurophysiology 92:2283-2294. #12;IU/COGS-Q580/Beer The Ionic Basis of the Action Potential Delcomyn, F. (1998
A Dynamic Model coupling Photoacclimation and Photoinhibition in Microalgae
Boyer, Edmond
A Dynamic Model coupling Photoacclimation and Photoinhibition in Microalgae Philipp Hartmann1, Andreas Nikolaou2, Beno^it Chachuat2, Olivier Bernard1 Abstract-- Microalgae are often considered a promising al- ternative for production of renewable energy, particularly as a potential producer
Modelling Dynamic Trust with Property Based Attestation in Trusted Platforms
Paris-Sud XI, Universit de
Modelling Dynamic Trust with Property Based Attestation in Trusted Platforms Aarthi Nagarajan attestation in trusted computing provides the ability to reason about the state of a platform using integrity attestation by abstracting low level binary values to high level security properties or functions of platforms
Fitting Dynamical Models to Observations of Globular Clusters
Dean E. McLaughlin
2003-02-14T23:59:59.000Z
The basic ingredients of models for the internal dynamics of globular clusters are reviewed, with an emphasis on the description of equilibrium configurations. The development of progressive complexity in the models is traced, concentrating on the inclusion of velocity anisotropy, rotation, and integrals of motion other than energy. Applications to observations of extragalactic globulars and to combined radial-velocity and proper-motion datasets are discussed.
Russell, Lynn
Geophysical Fluid Dynamics Laboratory general circulation model investigation of the indirect Corporation for Atmospheric Research, Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA V. Ramaswamy, Paul A. Ginoux, and Larry W. Horowitz Geophysical Fluid Dynamics Laboratory, Princeton, New
California at Irvine, University of
CVSys: A Coordination Framework for Dynamic and Fully Distributed Cardiovascular Modeling and dynamic simulation control. This coordination framework uniquely incorporates attributes of open indigenous and a more integrated system representation. Dynamic simulation control serves to interject new
A. Sulaksono; Naosad Alam; B. K. Agrawal
2014-11-03T23:59:59.000Z
The model dependence and the symmetry energy dependence of the core-crust transition properties for the neutron stars are studied using three different families of systematically varied extended relativistic mean field model. Several forces within each of the families are so considered that they yield wide variations in the values of the nuclear symmetry energy $a_{\\rm sym}$ and its slope parameter $L$ at the saturation density. The core-crust transition density is calculated using a method based on random-phase-approximation. The core-crust transition density is strongly correlated, in a model independent manner, with the symmetry energy slope parameter evaluated at the saturation density. The pressure at the transition point dose not show any meaningful correlations with the symmetry energy parameters at the saturation density. At best, pressure at the transition point is correlated with the symmetry energy parameters and their linear combination evaluated at the some sub-saturation density. Yet, such correlations might not be model independent. The correlations of core-crust transition properties with the symmetry energy parameter are also studied by varying the symmetry energy within a single model. The pressure at the transition point is correlated once again with the symmetry energy parameter at the sub-saturation density.
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gasenzer, Thomas [Universitat Heidelberg, Institut fur Theoretische Physik, Heidelberg (Germany); GSI, ExtreMe Matter Institute EMMI, Darmstadt (Germany); McLerran, Larry [Brookhaven National Laboratory, Physics Department, RIKEN BNL Research Center Upton NY (United States); China Central Normal University, Physics Department, Wuhan (China); Pawlowski, Jan M [Universitat Heidelberg, Institut fur Theoretische Physik, Heidelberg (Germany); GSI, ExtreMe Matter Institute EMMI, Darmstadt (Germany); Sexty, Denes [Universitat Heidelberg, Institut fur Theoretische Physik, Heidelberg (Germany); GSI, ExtreMe Matter Institute EMMI, Darmstadt (Germany)
2014-10-01T23:59:59.000Z
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of YangMills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gasenzer, Thomas; McLerran, Larry; Pawlowski, Jan M.; Sexty, Dnes
2014-10-01T23:59:59.000Z
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixedmorepoint of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of YangMills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.less
Modelling the chromosphere and transition region of Epsilon Eri (K2 V)
S. A. Sim; C. Jordan
2005-06-02T23:59:59.000Z
Measurements of ultraviolet line fluxes from Space Telescope Imaging Spectrograph and Far-Ultraviolet Spectroscopic Explorer spectra of the K2-dwarf Epsilon Eri are reported. These are used to develop new emission measure distributions and semi-empirical atmospheric models for the chromosphere and lower transition region of the star. These models are the most detailed constructed to date for a main-sequence star other than the Sun. New ionisation balance calculations, which account for the effect of finite density on dielectronic recombination rates, are presented for carbon, nitrogen, oxygen and silicon. The results of these calculations are significantly different from the standard Arnaud & Rothenflug ion balance, particularly for alkali-like ions. The new atmospheric models are used to place constraints on possible First Ionisation Potential (FIP) related abundance variations in the lower atmosphere and to discuss limitations of single-component models for the interpretation of certain optically thick line fluxes.
A dynamical symmetry breaking model in Weyl space
A. Feoli; W. R. Wood; G. Papini
1998-05-11T23:59:59.000Z
The dynamical process following the breaking of Weyl geometry to Riemannian geometry is considered by studying the motion of de Sitter bubbles in a Weyl vacuum. The bubbles are given in terms of an exact, spherically symmetric thin shell solution to the Einstein equations in a Weyl-Dirac theory with a time-dependent scalar field of the form beta = f(t)/r. The dynamical solutions obtained lead to a number of possible applications. An important feature of the thin shell model is the manner in which beta provides a connection between the interior and exterior geometries since information about the exterior geometry is contained in the boundary conditions for beta.
Gaussian Process Model for Collision Dynamics of Complex Molecules
Cui, Jie
2015-01-01T23:59:59.000Z
We show that a Gaussian Process model can be combined with a small number of scattering calculations to provide an accurate multi-dimensional dependence of scattering observables on the experimentally controllable parameters (such as the collision energy, temperature or external fields) as well as the potential energy surface parameters. This can be used for solving the inverse scattering problem, the prediction of collision properties of a specific molecular system based on the information for another molecule, the efficient calculation of thermally averaged observables and for reducing the error of the molecular dynamics calculations by averaging over the potential energy surface variations. We show that, trained by a combination of classical and quantum dynamics calculations, the model provides an accurate description of the scattering cross sections, even near scattering resonances. In this case, the classical calculations stabilize the model against uncertainties arising from wildly varying correlations ...
Mathematical Modeling of Microbial Community Dynamics: A Methodological Review
Song, Hyun-Seob; Cannon, William R.; Beliaev, Alex S.; Konopka, Allan
2014-10-17T23:59:59.000Z
Microorganisms in nature form diverse communities that dynamically change in structure and function in response to environmental variations. As a complex adaptive system, microbial communities show higher-order properties that are not present in individual microbes, but arise from their interactions. Predictive mathematical models not only help to understand the underlying principles of the dynamics and emergent properties of natural and synthetic microbial communities, but also provide key knowledge required for engineering them. In this article, we provide an overview of mathematical tools that include not only current mainstream approaches, but also less traditional approaches that, in our opinion, can be potentially useful. We discuss a broad range of methods ranging from low-resolution supra-organismal to high-resolution individual-based modeling. Particularly, we highlight the integrative approaches that synergistically combine disparate methods. In conclusion, we provide our outlook for the key aspects that should be further developed to move microbial community modeling towards greater predictive power.
Model for dynamic self-assembled magnetic surface structures.
Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.; Materials Science Division; Northwestern Univ.
2010-07-07T23:59:59.000Z
We propose a first-principles model for the dynamic self-assembly of magnetic structures at a water-air interface reported in earlier experiments. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended at a water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snakelike structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids.
Matsuda, Shigeki; Nakai, Mitsuru; Shimodaira, Hiroshi; Sagayama, Shigeki
We propose a new class of hidden Markov model (HMM) called asynchronous-transition HMM (AT-HMM). Opposed to conventional HMMs where hidden state transition occurs simultaneously to all features, the new class of HMM allows state transitions...
Modeling Dynamics in the Central Regions of Disk Galaxies
Isaac Shlosman
2004-12-07T23:59:59.000Z
The central regions of disk galaxies are hosts to supermassive black holes whose masses show a tight correlation with the properties of surrounding stellar bulges. While the exact origin of this dependency is not clear, it can be related to the very basic properties of dark matter halos and the associated gas and stellar dynamics in the central kpc of host galaxies. In this review we discuss some of the recent developments in modeling the wide spectrum of dynamical processes which can be affiliated with the above phenomena, such as the structure of molecular tori in AGN, structure formation in triaxial halos, and dissipative and non-dissipative dynamics in nested bar systems, with a particular emphasis on decoupling of gaseous nuclear bars. We also briefly touch on the subject of fueling the nuclear starbursts and AGN.
Reeves, Geoffrey D [Los Alamos National Laboratory; Friedel, Reiner H W [Los Alamos National Laboratory; Chen, Yue [Los Alamos National Laboratory; Koller, Josef [Los Alamos National Laboratory; Henderson, Michael G [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
The Dynamic Radiation Environment Assimilation Model (DREAM) was developed at Los Alamos National Laboratory to assess, quantify, and predict the hazards from the natural space environment and the anthropogenic environment produced by high altitude nuclear explosions (HANE). DREAM was initially developed as a basic research activity to understand and predict the dynamics of the Earth's Van Allen radiation belts. It uses Kalman filter techniques to assimilate data from space environment instruments with a physics-based model of the radiation belts. DREAM can assimilate data from a variety of types of instruments and data with various levels of resolution and fidelity by assigning appropriate uncertainties to the observations. Data from any spacecraft orbit can be assimilated but DREAM was designed to function with as few as two spacecraft inputs: one from geosynchronous orbit and one from GPS orbit. With those inputs, DREAM can be used to predict the environment at any satellite in any orbit whether space environment data are available in those orbits or not. Even with very limited data input and relatively simple physics models, DREAM specifies the space environment in the radiation belts to a high level of accuracy. DREAM has been extensively tested and evaluated as we transition from research to operations. We report here on one set of test results in which we predict the environment in a highly-elliptical polar orbit. We also discuss long-duration reanalysis for spacecraft design, using DREAM for real-time operations, and prospects for 1-week forecasts of the radiation belt environment.
Einarsson, Baldvin; Birnir, Bjorn; Sigursson, Sven .
2010-01-01T23:59:59.000Z
S.A.L.M. , 2010. Dynamic Energy Budget Theory For Metabolicthe use of dynamic energy budget theory. Biological Reviewsthrough dynamic energy budget models. Jour- nal of Animal
Colaiori, Francesca; Cuskley, Christine F; Loreto, Vittorio; Pugliese, Martina; Tria, Francesca
2014-01-01T23:59:59.000Z
Empirical evidence shows that the rate of irregular usage of English verbs exhibits discontinuity as a function of their frequency: the most frequent verbs tend to be totally irregular. We aim to qualitatively understand the origin of this feature by studying simple agent--based models of language dynamics, where each agent adopts an inflectional state for a verb and may change it upon interaction with other agents. At the same time, agents are replaced at some rate by new agents adopting the regular form. In models with only two inflectional states (regular and irregular), we observe that either all verbs regularize irrespective of their frequency, or a continuous transition occurs between a low frequency state where the lemma becomes fully regular, and a high frequency one where both forms coexist. Introducing a third (mixed) state, wherein agents may use either form, we find that a third, qualitatively different behavior may emerge, namely, a discontinuous transition in frequency. We introduce and solve an...
van Thienen, Peter
by a description of the implementation of solid state phase transitions of crustal and mantle material included Rc phase Rayleigh number gh3 0 S melt productivity function s-1 S entropy change upon full in the models. Finally, the implementa- tion of partial melting of crustal and mantle material and associated
Dark matter and strong electroweak phase transition in a radiative neutrino mass model
Ahriche, Amine [Department of Physics, University of Jijel, PB 98 Ouled Aissa, DZ-18000 Jijel (Algeria); Nasri, Salah, E-mail: aahriche@ictp.it, E-mail: snasri@uaeu.ac.ae [Physics Department, UAE University, POB 17551, Al Ain (United Arab Emirates)
2013-07-01T23:59:59.000Z
We consider an extension of the standard model (SM) with charged singlet scalars and right handed (RH) neutrinos all at the electroweak scale. In this model, the neutrino masses are generated at three loops, which provide an explanation for their smallness, and the lightest RH neutrino, N{sub 1}, is a dark matter candidate. We find that for three generations of RH neutrinos, the model can be consistent with the neutrino oscillation data, lepton flavor violating processes, N{sub 1} can have a relic density in agreement with the recent Planck data, and the electroweak phase transition can be strongly first order. We also show that the charged scalars may enhance the branching ratio h???, where as h??Z get can get few percent suppression. We also discuss the phenomenological implications of the RH neutrinos at the collider.
Non-equilibrium phase transition in an exactly solvable driven Ising model with friction
Alfred Hucht
2009-11-04T23:59:59.000Z
A driven Ising model with friction due to magnetic correlations has recently been proposed by Kadau et al. (Phys. Rev. Lett. 101, 137205 (2008)). The non-equilibrium phase transition present in this system is investigated in detail using analytical methods as well as Monte Carlo simulations. In the limit of high driving velocities $v$ the model shows mean field behavior due to dimensional reduction and can be solved exactly for various geometries. The simulations are performed with three different single spin flip rates: the common Metropolis and Glauber rates as well as a multiplicative rate. Due to the non-equilibrium nature of the model all rates lead to different critical temperatures at $v>0$, while the exact solution matches the multiplicative rate. Finally, the cross-over from Ising to mean field behavior as function of velocity and system size is analysed in one and two dimensions.
Pritam Chakraborty; S. Bulent Biner
2014-08-01T23:59:59.000Z
In this study, a unified cohesive zone model has been proposed to predict, Ductile to Brittle Transition, DBT, in Reactor Pressure Vessel, RPV, steels. A general procedure is described to obtain the Cohesive Zone Model, CZM, parameters for the different temperatures and fracture probabilities. In order to establish the full master-curve, the procedure requires three calibration points with one at the upper-shelf for ductile fracture and two for the fracture probabilities, Pf, of 5% and 95% at the lower-shelf. In the current study, these calibrations were carried out by utilizing the experimental fracture toughness values and flow curves. After the calibration procedure, the simulations of fracture behavior (ranging from completely unstable to stable crack extension behavior) in one inch thick compact tension specimens at different temperatures yielded values that were comparable to the experimental fracture toughness values, indicating the viability of such unified modeling approach.
Block entropy and quantum phase transition in the anisotropic Kondo necklace model
Mendoza-Arenas, J. J.; Franco, R.; Silva-Valencia, J. [Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia)
2010-06-15T23:59:59.000Z
We study the von Neumann block entropy in the Kondo necklace model for different anisotropies {eta} in the XY interaction between conduction spins using the density matrix renormalization group method. It was found that the block entropy presents a maximum for each {eta} considered, and, comparing it with the results of the quantum criticality of the model based on the behavior of the energy gap, we observe that the maximum block entropy occurs at the quantum critical point between an antiferromagnetic and a Kondo singlet state, so this measure of entanglement is useful for giving information about where a quantum phase transition occurs in this model. We observe that the block entropy also presents a maximum at the quantum critical points that are obtained when an anisotropy {Delta} is included in the Kondo exchange between localized and conduction spins; when {Delta} diminishes for a fixed value of {eta}, the critical point increases, favoring the antiferromagnetic phase.
Dynamic Absorption Model for Off-Gas Separation
Veronica J. Rutledge
2011-07-01T23:59:59.000Z
Modeling and simulations will aid in the future design of U.S. advanced reprocessing plants for the recovery and recycle of actinides in used nuclear fuel. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, a rate based, dynamic absorption model is being developed in gPROMS software. Inputs include liquid and gas stream constituents, column properties, liquid and gas phase reactions, number of stages, and inlet conditions. It simulates multiple component absorption with countercurrent flow and accounts for absorption by mass transfer and chemical reaction. The assumption of each stage being a discrete well-mixed entity was made. Therefore, the model is solved stagewise. The simulation outputs component concentrations in both phases as a function of time from which the rate of absorption is determined. Temperature of both phases is output as a function of time also. The model will be used able to be used as a standalone model in addition to in series with other off-gas separation unit operations. The current model is being generated based on NOx absorption; however, a future goal is to develop a CO2 specific model. The model will have the capability to be modified for additional absorption systems. The off-gas models, both adsorption and absorption, will be made available via the server or web for evaluation by customers.
Dynamics of Matter in a Compactified Kaluza-Klein Model
Valentino Lacquaniti; Giovanni Montani
2009-02-10T23:59:59.000Z
A longstanding problem in Kaluza-Klein models is the description of matter dynamics. Within the 5D model, the dimensional reduction of the geodesic motion for a 5D free test particle formally restores electrodynamics, but the reduced 4D particle shows a charge-mass ratio that is upper bounded, such that it cannot fit to any kind of elementary particle. At the same time, from the quantum dynamics viewpoint, there is the problem of the huge massive modes generation. We present a criticism against the 5D geodesic approach and face the hypothesis that in Kaluza-Klein space the geodesic motion does not deal with the real dynamics of test particle. We propose a new approach: starting from the conservation equation for the 5D matter tensor, within the Papapetrou multipole expansion, we prove that the 5D dynamical equation differs from the 5D geodesic one. Our new equation provides right coupling terms without bounding and in such a scheme the tower of massive modes is removed.
Model of a deterministic detector and dynamical decoherence
Lee, Jae Weon; Shepelyansky, Dima L. [Laboratoire de Physique Theorique, UMR 5152 du CNRS, Univ. P. Sabatier, 31062 Toulouse Cedex 4 (France); Averin, Dmitri V. [Department of Physics, University of Stony Brook, SUNY, Stony Brook, New York 11794 (United States); Benenti, Giuliano [Center for Nonlinear and Complex Systems, Universita degli Studi dell'Insubria and Istituto Nazionale per la Fisica della Materia, Unita di Como, Via Valleggio 11, 22100 Como (Italy)
2005-07-15T23:59:59.000Z
We discuss a deterministic model of detector coupled to a two-level system (a qubit). The detector is a quasiclassical object whose dynamics is described by the kicked rotator Hamiltonian. We show that in the regime of quantum chaos the detector acts as a chaotic bath and induces decoherence of the qubit. We discuss the dephasing and relaxation rates and demonstrate that the main features of single-qubit decoherence due to a heat bath can be reproduced by our fully deterministic dynamical model. Moreover, we show that, for strong enough qubit-detector coupling, the dephasing rate is given by the rate of exponential instability of the detector's dynamics, that is, by the Lyapunov exponent of classical motion. Finally, we discuss the measurement in the regimes of strong and weak qubit-detector coupling. For the case of strong coupling the detector performs a measurement of the up/down state of the qubit. In the case of weak coupling, due to chaos, the dynamical evolution of the detector is strongly sensitive to the state of the qubit. However, in this case it is unclear how to extract a signal from any measurement with a coarse-graining in the phase space on a size much larger than the Planck cell.
Keratin Dynamics: Modeling the Interplay between Turnover and Transport
Stephanie Portet; Anotida Madzvamuse; Andy Chung; Rudolf E. Leube; Reinhard Windoffer
2015-04-01T23:59:59.000Z
Keratin are among the most abundant proteins in epithelial cells. Functions of the keratin network in cells are shaped by their dynamical organization. Using a collection of experimentally-driven mathematical models, different hypotheses for the turnover and transport of the keratin material in epithelial cells are tested. The interplay between turnover and transport and their effects on the keratin organization in cells are hence investigated by combining mathematical modeling and experimental data. Amongst the collection of mathematical models considered, a best model strongly supported by experimental data is identified. Fundamental to this approach is the fact that optimal parameter values associated with the best fit for each model are established. The best candidate among the best fits is characterized by the disassembly of the assembled keratin material in the perinuclear region and an active transport of the assembled keratin. Our study shows that an active transport of the assembled keratin is required to explain the experimentally observed keratin organization.
Dynamical Wave Function Collapse Models in Quantum Measure Theory
Fay Dowker; Yousef Ghazi-Tabatabai
2008-05-15T23:59:59.000Z
The structure of Collapse Models is investigated in the framework of Quantum Measure Theory, a histories-based approach to quantum mechanics. The underlying structure of coupled classical and quantum systems is elucidated in this approach which puts both systems on a spacetime footing. The nature of the coupling is exposed: the classical histories have no dynamics of their own but are simply tied, more or less closely, to the quantum histories.
Dynamic ModelingDynamic Modeling the Electric Power Networkthe Electric Power Network
Oro, Daniel
at the National Energy Modeling System/Annual Energy Outlook Conference, Washington, DC, March 10, 2003] #12
Best practices for system dynamics model design and construction with powersim studio.
Malczynski, Leonard A.
2011-06-01T23:59:59.000Z
This guide addresses software quality in the construction of Powersim{reg_sign} Studio 8 system dynamics simulation models. It is the result of almost ten years of experience with the Powersim suite of system dynamics modeling tools (Constructor and earlier Studio versions). It is a guide that proposes a common look and feel for the construction of Powersim Studio system dynamics models.
Efficient Dynamic Modeling, Numerical Optimal Control and Experimental Results for Various Gaits
Stryk, Oskar von
Efficient Dynamic Modeling, Numerical Optimal Control and Experimental Results for Various Gaits. A fully three- dimensional dynamical model of Sony's four-legged robot is used to state an optimal control model and the algorithm for evaluating the dynamics. The formulation of the optimal control problem
Learning Multiple Models of Non-Linear Dynamics for Control under Varying Contexts
Vijayakumar, Sethu
Learning Multiple Models of Non-Linear Dynamics for Control under Varying Contexts Georgios Petkos for adaptive motor control exist which learn the system's inverse dynamics online and use this single model;II Command Context 1 Context 2 Dynamics models Context n Control Learning Commands Switch / Mix
AIAA 2001-2126 DYNAMICAL MODELS FOR CONTROL OF CAVITY OSCILLATIONS
Dabiri, John O.
AIAA 2001-2126 DYNAMICAL MODELS FOR CONTROL OF CAVITY OSCILLATIONS Clarence W. Rowley Tim Colonius have used an explicit dynamical model for control design, or analysis of performance or robustness, CA 91125 Abstract We investigate nonlinear dynamical models for self- sustained oscillations
Learning Multiple Models of Non-Linear Dynamics for Control under Varying Contexts
Toussaint, Marc
Learning Multiple Models of Non-Linear Dynamics for Control under Varying Contexts Georgios Petkos for adaptive motor control exist which learn the system's inverse dynamics online and use this single model version - to appear in ICANN 2006 #12;II Command Context 1 Context 2 Dynamics models Context n Control
Load estimation and control using learned dynamics models Georgios Petkos and Sethu Vijayakumar
Vijayakumar, Sethu
Load estimation and control using learned dynamics models Georgios Petkos and Sethu Vijayakumar with their robustness in light of imperfect, intermediate dynamic models. I. INTRODUCTION Adaptive control the learned dynamics for control. In Section IV, we see how from a set of learned models with known inertial
Direct Modeling of Envelope Dynamics in Resonant Inverters Yan Yin, Regan Zane, Robert Erickson
to facilitate optimized controller design. Several approaches are available to model the envelope dynamicsDirect Modeling of Envelope Dynamics in Resonant Inverters Yan Yin, Regan Zane, Robert Erickson- This paper provides a direct dynamic modeling approach for envelope signals in resonant inverters driven
Nuclear Hybrid Energy System Modeling: RELAP5 Dynamic Coupling Capabilities
Piyush Sabharwall; Nolan Anderson; Haihua Zhao; Shannon Bragg-Sitton; George Mesina
2012-09-01T23:59:59.000Z
The nuclear hybrid energy systems (NHES) research team is currently developing a dynamic simulation of an integrated hybrid energy system. A detailed simulation of proposed NHES architectures will allow initial computational demonstration of a tightly coupled NHES to identify key reactor subsystem requirements, identify candidate reactor technologies for a hybrid system, and identify key challenges to operation of the coupled system. This work will provide a baseline for later coupling of design-specific reactor models through industry collaboration. The modeling capability addressed in this report focuses on the reactor subsystem simulation.
Bulk viscosity and the phase transition of the linear sigma model
Antonio Dobado; Juan M. Torres-Rincon
2012-10-04T23:59:59.000Z
In this work we deal with the critical behavior of the bulk viscosity in the linear sigma model (LSM) as an example of a system which can be treated by using different techniques. Starting from the Boltzmann-Uehling-Uhlenbeck equation we compute the bulk viscosity over entropy density of the LSM in the large-N limit. We search for a possible maximum of the bulk viscosity over entropy density at the critical temperature of the chiral phase transition. The information about this critical temperature, as well as the effective masses, is obtained from the effective potential. We find that the expected maximum (as a measure of the conformality loss) is absent in the large N in agreement with other models in the same limit. However, this maximum appears when, instead of the large-N limit, the Hartree approximation within the Cornwall-Jackiw-Tomboulis (CJT) formalism is used. Nevertheless, this last approach to the LSM does not give rise to the Goldstone theorem and also predicts a first order phase transition instead of the expected second order one. Therefore both, the large-N limit and the CJT-Hartree approximations, should be considered as complementary for the study of the critical behavior of the bulk viscosity in the LSM.
User Guide for PV Dynamic Model Simulation Written on PSCAD Platform
Muljadi, E.; Singh, M.; Gevorgian, V.
2014-11-01T23:59:59.000Z
This document describes the dynamic photovoltaic model developed by the National Renewable Energy Laboratory and is intended as a guide for users of these models.
Pulse control of sudden transition for two qubits in XY spin baths and quantum phase transition
Da-Wei Luo; Hai-Qing Lin; Jing-Bo Xu; Dao-Xin Yao
2011-11-03T23:59:59.000Z
We study the dynamics of two initially correlated qubits coupled to their own separate spin baths modeled by a XY spin chain and find the explicit expression of the quantum discord for the system. A sudden transition is found to exist between classical and quantum decoherence by choosing certain initial states. We show that the sudden transition happens near the critical point, which provides a new way to characterize the quantum phase transition. Furthermore, we propose a scheme to prolong the transition time of the quantum discord by applying the bang-bang pulses.
Modelling the e#ects of air pollution on health using Bayesian Dynamic Generalised Linear Models
Bath, University of
Modelling the e#ects of air pollution on health using Bayesian Dynamic Generalised Linear Models 1 Introduction The potential detrimental e#ects of ambient air pollution is a major issue in public (2004)). Large multicity studies such as `Air pollution and health: a European approach' (APHEA
Code description: A dynamic modelling strategy for Bayesian computer model emulation
West, Mike
Code description: A dynamic modelling strategy for Bayesian computer model emulation 1 Example data and code directory The example data is provided under the directory "mydata": · "design1.dat": this file2.dat": this file contains the 60 validation runs. The Matlab code is provided under the directory
Eulerian hydrocode modeling of a dynamic tensile extrusion experiment (u)
Burkett, Michael W [Los Alamos National Laboratory; Clancy, Sean P [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
Eulerian hydrocode simulations utilizing the Mechanical Threshold Stress flow stress model were performed to provide insight into a dynamic extrusion experiment. The dynamic extrusion response of copper (three different grain sizes) and tantalum spheres were simulated with MESA, an explicit, 2-D Eulerian continuum mechanics hydrocode and compared with experimental data. The experimental data consisted of high-speed images of the extrusion process, recovered extruded samples, and post test metallography. The hydrocode was developed to predict large-strain and high-strain-rate loading problems. Some of the features of the features of MESA include a high-order advection algorithm, a material interface tracking scheme and a van Leer monotonic advection-limiting. The Mechanical Threshold Stress (MTS) model was utilized to evolve the flow stress as a function of strain, strain rate and temperature for copper and tantalum. Plastic strains exceeding 300% were predicted in the extrusion of copper at 400 m/s, while plastic strains exceeding 800% were predicted for Ta. Quantitative comparisons between the predicted and measured deformation topologies and extrusion rate were made. Additionally, predictions of the texture evolution (based upon the deformation rate history and the rigid body rotations experienced by the copper during the extrusion process) were compared with the orientation imaging microscopy measurements. Finally, comparisons between the calculated and measured influence of the initial texture on the dynamic extrusion response of tantalum was performed.
Dynamic mesoscale model of dipolar fluids via fluctuating hydrodynamics
Persson, Rasmus A. X.; Chu, Jhih-Wei, E-mail: jwchu@nctu.edu.tw [Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu 30068, Taiwan (China); Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30068, Taiwan (China); Voulgarakis, Nikolaos K. [Department of Mathematics, Washington State University, Richland, Washington 99372 (United States)
2014-11-07T23:59:59.000Z
Fluctuating hydrodynamics (FHD) is a general framework of mesoscopic modeling and simulation based on conservational laws and constitutive equations of linear and nonlinear responses. However, explicit representation of electrical forces in FHD has yet to appear. In this work, we devised an Ansatz for the dynamics of dipole moment densities that is linked with the Poisson equation of the electrical potential ? in coupling to the other equations of FHD. The resulting ?-FHD equations then serve as a platform for integrating the essential forces, including electrostatics in addition to hydrodynamics, pressure-volume equation of state, surface tension, and solvent-particle interactions that govern the emergent behaviors of molecular systems at an intermediate scale. This unique merit of ?-FHD is illustrated by showing that the water dielectric function and ion hydration free energies in homogeneous and heterogenous systems can be captured accurately via the mesoscopic simulation. Furthermore, we show that the field variables of ?-FHD can be mapped from the trajectory of an all-atom molecular dynamics simulation such that model development and parametrization can be based on the information obtained at a finer-grained scale. With the aforementioned multiscale capabilities and a spatial resolution as high as 5 , the ?-FHD equations represent a useful semi-explicit solvent model for the modeling and simulation of complex systems, such as biomolecular machines and nanofluidics.
A model of phase transitions in the system of electro-optical dipolar chromophores subject to an electric field Yuriy V. Pereverzev, Oleg V. Prezhdo,a) and Larry R. Dalton Department of Chemistry An analytical model for the nonlinear behavior of the electro-optic EO coefficient in chro- mophore
Asbeck, Peter M.
mi': iaE Large-Signal HBT Model with Improved Collector Transit Time Formulation for GaAs and In large-signal HBT model which accurately accounts for the intricate hias dependence of collector delay collector delay function accounts for the variation of electron velocity with electric field
Zero gravity two-phase flow regime transition modeling compared with data and relap5-3d predictions
Ghrist, Melissa Renee
2009-05-15T23:59:59.000Z
This thesis compares air/water two-phase flow regime transition models in zero gravity with data and makes recommendations for zero gravity models to incorporate into the RELAP5-3D thermal hydraulic computer code. Data from numerous researchers...
John Bulava; Philip Gerhold; Karl Jansen; Jim Kallarackal; Attila Nagy
2011-11-11T23:59:59.000Z
We study a chirally invariant Higgs-Yukawa model regulated on a space-time lattice. We calculate Higgs boson resonance parameters and mass bounds for various values of the mass of the degenerate fermion doublet. Also, first results on the phase transition temperature are presented. In general, this model may be relevant for BSM scenarios with a heavy fourth generation of quarks.
The Hamiltonian Mean Field model: effect of network structure on synchronization dynamics
Yogesh S. Virkar; Juan G. Restrepo; James D. Meiss
2015-03-16T23:59:59.000Z
The Hamiltonian Mean Field (HMF) model of coupled inertial, Hamiltonian rotors is a prototype for conservative dynamics in systems with long-range interactions. We consider the case where the interactions between the rotors are governed by a network described by a weighted adjacency matrix. By studying the linear stability of the incoherent state, we find that the transition to synchrony occurs at a coupling constant $K$ inversely proportional to the largest eigenvalue of the adjacency matrix. We derive a closed system of equations for a set of local order parameters and use these equations to study the effect of network heterogeneity on the synchronization of the rotors. We find that for values of $K$ just beyond the transition to synchronization the degree of synchronization is highly dependent on the network's heterogeneity, but that for large values of $K$ the degree of synchronization is robust to changes in the heterogeneity of the network's degree distribution. Our results are illustrated with numerical simulations on Erd\\"os-Renyi networks and networks with power-law degree distributions.
Computational fluid dynamic modeling of fluidized-bed polymerization reactors
Rokkam, Ram [Ames Laboratory
2012-11-02T23:59:59.000Z
Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.
Nucleon-nucleon interaction in the chromodielectric soliton model: Dynamics
Pepin, S.; Stancu, F. [Universite de Liege, Institut de Physique B.5, Sart-Tilman, B-4000 Liege 1 (Belgium)] [Universite de Liege, Institut de Physique B.5, Sart-Tilman, B-4000 Liege 1 (Belgium); Koepf, W. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978 Tel Aviv (Israel)] [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978 Tel Aviv (Israel); Wilets, L. [Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)] [Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)
1996-03-01T23:59:59.000Z
The present work is an extension of a previous study of the nucleon-nucleon interaction based on the chromodielectric soliton model. The former approach was static, leading to an adiabatic potential. Here we perform a dynamical study in the framework of the generator coordinate method. In practice we derive an approximate Hill-Wheeler differential equation and obtain a local nucleon-nucleon potential as a function of a mean generator coordinate. This coordinate is related to an effective separation distance between the two nucleons by a Fujiwara transformation. This latter relationship is especially useful in studying the quark substructure of light nuclei. We investigate the explicit contribution of the one-gluon exchange part of the six-quark Hamiltonian to the nucleon-nucleon potential, and we find that the dynamics are responsible for a significant part of the short-range {ital N}-{ital N} repulsion. {copyright} {ital 1996 The American Physical Society.}
Optimization of Fed-Batch Saccharomyces cereWisiae Fermentation Using Dynamic Flux Balance Models
Mountziaris, T. J.
ARTICLES Optimization of Fed-Batch Saccharomyces cereWisiae Fermentation Using Dynamic Flux Balance metabolism with dynamic mass balances on key extracellular species. Model-based dynamic optimization concentration profiles, and the final batch time are treated as decision variables in the dynamic optimization
Fayer, Michael D.
Ultrafast Structural Dynamics Inside Planar Phospholipid Multibilayer Model Cell Membranes Measured diffusion caused by the structural dynamics of the membrane from 200 fs to 200 ps as a function structure and an abrupt change in dynamics at 35% cholesterol. The dynamics are independent of cholesterol
Explorations in combining cognitive models of individuals and system dynamics models of groups.
Backus, George A.
2008-07-01T23:59:59.000Z
This report documents a demonstration model of interacting insurgent leadership, military leadership, government leadership, and societal dynamics under a variety of interventions. The primary focus of the work is the portrayal of a token societal model that responds to leadership activities. The model also includes a linkage between leadership and society that implicitly represents the leadership subordinates as they directly interact with the population. The societal model is meant to demonstrate the efficacy and viability of using System Dynamics (SD) methods to simulate populations and that these can then connect to cognitive models depicting individuals. SD models typically focus on average behavior and thus have limited applicability to describe small groups or individuals. On the other hand, cognitive models readily describe individual behavior but can become cumbersome when used to describe populations. Realistic security situations are invariably a mix of individual and population dynamics. Therefore, the ability to tie SD models to cognitive models provides a critical capability that would be otherwise be unavailable.
Mechanical reaction-diffusion model for bacterial population dynamics
Ngamsaad, Waipot
2015-01-01T23:59:59.000Z
The effect of mechanical interaction between cells on the spreading of bacterial population was investigated in one-dimensional space. A nonlinear reaction-diffusion equation has been formulated as a model for this dynamics. In this model, the bacterial cells are treated as the rod-like particles that interact, when contacting each other, through the hard-core repulsion. The repulsion introduces the exclusion process that causes the fast diffusion in bacterial population at high density. The propagation of the bacterial density as the traveling wave front in long time behavior has been analyzed. The analytical result reveals that the front speed is enhanced by the exclusion process---and its value depends on the packing fraction of cell. The numerical solutions of the model have been solved to confirm this prediction.
A model of riots dynamics: shocks, diffusion and thresholds
Berestycki, Henri; Rodriguez, Nancy
2015-01-01T23:59:59.000Z
We introduce and analyze several variants of a system of differential equations which model the dynamics of social outbursts, such as riots. The systems involve the coupling of an explicit variable representing the intensity of rioting activity and an underlying (implicit) field of social tension. Our models include the effects of exogenous and endogenous factors as well as various propagation mechanisms. From numerical and mathematical analysis of these models we show that the assumptions made on how different locations influence one another and how the tension in the system disperses play a major role on the qualitative behavior of bursts of social unrest. Furthermore, we analyze here various properties of these systems, such as the existence of traveling wave solutions, and formulate some new open mathematical problems which arise from our work.
The Third State of the Schelling Model of Residential Dynamics
Benenson, Itzhak
2009-01-01T23:59:59.000Z
The Schelling model of segregation between two groups of residential agents (Schelling 1971; Schelling 1978) reflects the most abstract view of the non-economic forces of residential migrations: be close to people of 'your own'. The model assumes that the residential agent, located in the neighborhood where the fraction of 'friends' is less than a predefined threshold value F, tries to relocate to a neighborhood for which this fraction is above F. It is well known that for the equal groups, depending on F, Schelling's residential pattern converges either to complete integration (random pattern) or segregation. We investigate Schelling model pattern dynamics as dependent on F, the ratio of the group numbers and the size of the neighborhood and demonstrate that the traditional integrate-segregate dichotomy is incomplete. In case of unequal groups, there exists the wide interval of the F-values that entails the third persistent residential pattern, in which part of the majority population segregates, while the r...
Fabrycky, Daniel C. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Ford, Eric B.; Moorhead, Althea V. [Astronomy Department, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32111 (United States); Steffen, Jason H. [Fermilab Center for Particle Astrophysics, P.O. Box 500, MS 127, Batavia, IL 60510 (United States); Rowe, Jason F.; Christiansen, Jessie L. [SETI Institute, Mountain View, CA 94043 (United States); Carter, Joshua A.; Fressin, Francois; Geary, John [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Batalha, Natalie M. [Department of Physics and Astronomy, San Jose State University, San Jose, CA 95192 (United States); Borucki, William J.; Bryson, Steve; Haas, Michael R. [NASA Ames Research Center, Moffett Field, CA, 94035 (United States); Buchhave, Lars A. [Department of Astrophysics and Planetary Science, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Ciardi, David R. [NASA Exoplanet Science Institute/Caltech, Pasadena, CA 91126 (United States); Cochran, William D.; Endl, Michael [McDonald Observatory, The University of Texas, Austin TX 78730 (United States); Fanelli, Michael N. [Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Fischer, Debra [Astronomy Department, Yale University, New Haven, CT (United States); Hall, Jennifer R., E-mail: daniel.fabrycky@gmail.com [Orbital Sciences Corporation/NASA Ames Research Center, Moffett Field, CA 94035 (United States); and others
2012-05-10T23:59:59.000Z
Eighty planetary systems of two or more planets are known to orbit stars other than the Sun. For most, the data can be sufficiently explained by non-interacting Keplerian orbits, so the dynamical interactions of these systems have not been observed. Here we present four sets of light curves from the Kepler spacecraft, each which of shows multiple planets transiting the same star. Departure of the timing of these transits from strict periodicity indicates that the planets are perturbing each other: the observed timing variations match the forcing frequency of the other planet. This confirms that these objects are in the same system. Next we limit their masses to the planetary regime by requiring the system remain stable for astronomical timescales. Finally, we report dynamical fits to the transit times, yielding possible values for the planets' masses and eccentricities. As the timespan of timing data increases, dynamical fits may allow detailed constraints on the systems' architectures, even in cases for which high-precision Doppler follow-up is impractical.
Supercooling and phase coexistence in cosmological phase transitions
Megevand, Ariel; Sanchez, Alejandro D. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Dean Funes 3350, (7600) Mar del Plata (Argentina)
2008-03-15T23:59:59.000Z
Cosmological phase transitions are predicted by particle physics models, and have a variety of important cosmological consequences, which depend strongly on the dynamics of the transition. In this work we investigate in detail the general features of the development of a first-order phase transition. We find thermodynamical constraints on some quantities that determine the dynamics, namely, the latent heat, the radiation energy density, and the false-vacuum energy density. Using a simple model with a Higgs field, we study numerically the amount and duration of supercooling and the subsequent reheating and phase coexistence. We analyze the dependence of the dynamics on the different parameters of the model, namely, the energy scale, the number of degrees of freedom, and the couplings of the scalar field with bosons and fermions. We also inspect the implications for the cosmological outcomes of the phase transition.
Xiao, Heng; Gustafson, William I.; Wang, Hailong
2014-04-29T23:59:59.000Z
Subgrid-scale interactions between turbulence and radiation are potentially important for accurately reproducing marine low clouds in climate models. To better understand the impact of these interactions, the Weather Research and Forecasting (WRF) model is configured for large eddy simulation (LES) to study the stratocumulus-to-trade cumulus (Sc-to-Cu) transition. Using the GEWEX Atmospheric System Studies (GASS) composite Lagrangian transition case and the Atlantic Trade Wind Experiment (ATEX) case, it is shown that the lack of subgrid-scale turbulence-radiation interaction, as is the case in current generation climate models, accelerates the Sc-to-Cu transition. Our analysis suggests that in cloud-topped boundary layers subgrid-scale turbulence-radiation interactions contribute to stronger production of temperature variance, which in turn leads to stronger buoyancy production of turbulent kinetic energy and helps to maintain the Sc cover.
Towards a Simplified Dynamic Wake Model using POD Analysis
Bastine, David; Wchter, Matthias; Peinke, Joachim
2014-01-01T23:59:59.000Z
We apply the proper orthogonal decomposition (POD) to large eddy simulation data of a wind turbine wake in a turbulent atmospheric boundary layer. The turbine is modeled as an actuator disk. Our analyis mainly focuses on the question whether POD could be a useful tool to develop a simplified dynamic wake model. The extracted POD modes are used to obtain approximate descriptions of the velocity field. To assess the quality of these POD reconstructions, we define simple measures which are believed to be relevant for a sequential turbine in the wake such as the energy flux through a disk in the wake. It is shown that only a few modes are necessary to capture basic dynamical aspects of these measures even though only a small part of the turbulent kinetic energy is restored. Furthermore, we show that the importance of the individual modes depends on the measure chosen. Therefore, the optimal choice of modes for a possible model could in principle depend on the application of interest. We additionally present a pos...
Modelling and Verification of Automated Transit Systems, Using Timed Automata, Invariants and
Lynch, Nancy
and gates, steam boiler control) appear in [8, 10]. Briefly, a timed automaton is a labelled transition
Modelling and Veri cation of Automated Transit Systems, using Timed Automata, Invariants and
Lynch, Nancy
and gates, steam boiler control) appear in 8, 10]. Brie y, a timed automaton is a labelled transition system
Li, Yangmin
Dynamic Modeling and Adaptive Neural-Fuzzy Control for Nonholonomic Mobile Manipulators Moving on a Slope 1 Dynamic Modeling and Adaptive Neural-Fuzzy Control for Nonholonomic Mobile Manipulators Moving manipulator, neural-fuzzy control, nonholonomic. 1. INTRODUCTION Intelligent and autonomous mobile
Ice sheets and their dynamics Continuum thermo-mechanical model of a glacier
Cerveny, Vlastislav
Ice sheets and their dynamics Continuum thermo-mechanical model of a glacier Shallow Ice Approximation (SIA) SIA-I Iterative Improvement Technique Benchmarks Numerical modeling of ice-sheet dynamics and Cartography, Zdiby 1.6.2010 Ondej Soucek Ph.D. defense #12;Ice sheets and their dynamics Continuum thermo
Polymer dynamics in repton model at large fields Anatoly B. Kolomeisky
Polymer dynamics in repton model at large fields Anatoly B. Kolomeisky Department of Chemistry, Poland Received 22 October 2003; accepted 26 January 2004 Polymer dynamics at large fields in Rubinstein simple exclusion models are used to analyze the reptation dynamics of polymers. It is found
A LUMPED-PARAMETER DYNAMIC MODEL OF A THERMAL REGENERATOR FOR FREE-PISTON STIRLING ENGINES
Barth, Eric J.
A LUMPED-PARAMETER DYNAMIC MODEL OF A THERMAL REGENERATOR FOR FREE-PISTON STIRLING ENGINES Mark the mass flow, piston dynamics, and control volume behavior inside a free-piston Stirling engine. A new model for a Stirling engine thermal regenerator that incorporates a dynamically changing temperature
Guang-Hua Liu; Wei Li; Wen-Long You; Guang-Shan Tian; Gang Su
2012-06-02T23:59:59.000Z
The matrix product state (MPS) is utilized to study the ground state properties and quantum phase transitions (QPTs) of the one-dimensional quantum compass model (QCM). The MPS wavefunctions are argued to be very efficient descriptions of QCM ground states, and are numerically determined by imaginary time projections. The ground state energy, correlations, quantum entanglement and its spectrum, local and nonlocal order parameters, etc., are calculated and studied in details. It is revealed that the bipartite and block entanglement entropies, as well as the nearest neighbor correlation functions can be used to detect the second-order QPTs, but not the first-order ones, while fidelity detections can recognize both. The entanglement spectrum is extracted from the MPS wavefunction, and found to be doubly degenerate in disordered phases of QCM, where non-local string order parameters exist. Moreover, with linearized tensor renormalization group method, the specific heat curves are evaluated and their low temperature behaviors are investigated.
A simple microscopic model for the dynamics of adhesive failure
Dominic Vella; L. Mahadevan
2005-12-27T23:59:59.000Z
We consider a microscopic model for the failure of soft adhesives in tension based on ideas of bond rupture under dynamic loading. Focusing on adhesive failure under loading at constant velocity, we demonstrate that bi-modal curves of stress against strain may occur due to effects of finite polymer chain or bond length and characterise the loading conditions under which such bi-modal behaviour is observed. The results of this analysis are in qualitative agreement with experiments performed on unconfined adhesives in which failure does not occur by cavitation.
Validation of DWPF MOG dynamics model -- Phase 1
Choi, A.S.
1996-09-23T23:59:59.000Z
The report documents the results of a study to validate the DWPF melter off-gas system dynamics model using the data collected during the Waste Qualification Runs in 1995. The study consisted of: (1) calibration of the model using one set of melter idling data, (2) validation of the calibrated model using three sets of steady feeding and one set of transient data, and (3) application of the validated model to simulate the melter overfeeding incident which took place on 7/5.95. All the controller tuning constants and control logic used in the validated model are identical to those used in the DCS in 1995. However, the model does not reflect any design and/or operational changes made in 1996 to alleviate the glass pouring problem. Based on the results of the overfeeding simulation, it is concluded that the actual feed rates during that incident were about 2.75 times the indicated readings and that the peak concentration of combustible gases remained below 15% of the lower flammable limit during the entire one-hour duration.
Designability, thermodynamic stability, and dynamics in protein folding: A lattice model study
Levine, Alex J.
Designability, thermodynamic stability, and dynamics in protein folding: A lattice model study Re October 1998 In the framework of a lattice-model study of protein folding, we investigate the interplay model. Lattice models have been widely used in the study of protein folding dynamics.28 The main
Learning Multiple Models of Non-Linear Dynamics for Control under Varying Contexts
Petkos, Georgios; Toussaint, Marc; Vijayakumar, Sethu
For stationary systems, efficient techniques for adaptive motor control exist which learn the systems inverse dynamics online and use this single model for control. However, in realistic domains the system dynamics often ...
Griffith, Daniel Todd
2005-02-17T23:59:59.000Z
The main objective of this work is to demonstrate some new computational methods for estimation, optimization and modeling of dynamical systems that use automatic differentiation. Particular focus will be upon dynamical ...
Examination of temporal DDT trends in Lake Erie fish communities using dynamic linear modeling
Arhonditsis, George B.
Examination of temporal DDT trends in Lake Erie fish communities using dynamic linear modeling 25 July 2013 Communicated by Dr. Erik Christensen Keywords: DDT Bayesian inference Dynamic linear (DDT) was initially heralded for its effectiveness against malaria and agricultural pests
Chen, Yong
or applying an estimation method that is robust to the error structure assumption in modelling the dynamicsCan a more realistic model error structure improve the parameter estimation in modelling the dynamics of sh populations? Y. Chena,* , J.E. Paloheimob a Fisheries Conservation Chair Program, Fisheries
Dissipative particle dynamics model for colloid transport in porous media
Pan, Wenxiao; Tartakovsky, Alexandre M.
2013-08-01T23:59:59.000Z
We present that the transport of colloidal particles in porous media can be effectively modeled with a new formulation of dissipative particle dynamics, which augments standard DPD with non-central dissipative shear forces between particles while preserving angular momentum. Our previous studies have demonstrated that the new formulation is able to capture accurately the drag forces as well as the drag torques on colloidal particles that result from the hydrodynamic retardation e?ect. In the present work, we use the new formulation to study the contact e?ciency in colloid ?ltration in saturated porous media. Note that the present model include all transport mechanisms simultaneously, including gravitational sedimentation, interception and Brownian di?usion. Our results of contact e?ciency show a good agreement with the predictions of the correlation equation proposed by Tufenkji and EliMelech, which also incorporate all transport mechanisms simultaneously without the additivity assumption.
Dynamic chirality in the interacting boson fermion-fermion model
Brant, S. [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Tonev, D. [INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Institute for Nuclear Research and Nuclear Energy, BAS, 1784 Sofia (Bulgaria); De Angelis, G. [INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Ventura, A. [Ente per le Nuove tecnologie, l'Energia e l'Ambiente, I-40129 Bologna and Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (Italy)
2008-09-15T23:59:59.000Z
The chiral interpretation of twin bands in odd-odd nuclei was investigated in the interacting boson fermion-fermion model. The analysis of the wave functions has shown that the possibility for angular momenta of the valence proton, neutron and core to find themselves in the favorable, almost orthogonal geometry is present, but not dominant. Such behavior is found to be similar in nuclei where both the level energies and the electromagnetic decay properties display the chiral pattern, as well as in those where only the level energies of the corresponding levels in the twin bands are close together. The difference in the structure of the two types of chiral candidates nuclei can be attributed to different {beta} and {gamma} fluctuations, induced by the exchange boson-fermion interaction of the interacting boson fermion-fermion model. In both cases the chirality is weak and dynamic.
nver, Hakk? zgr
2008-01-01T23:59:59.000Z
Scholars have developed a range of qualitative and quantitative models for generalizing the dynamics of technological innovation and identifying patterns of competition between rivals. This thesis compares two predominant ...
Model Studies of the Dynamics of Bacterial Flagellar Motors
Bai, F; Lo, C; Berry, R; Xing, J
2009-03-19T23:59:59.000Z
The Bacterial Flagellar Motor is a rotary molecular machine that rotates the helical filaments which propel swimming bacteria. Extensive experimental and theoretical studies exist on the structure, assembly, energy input, power generation and switching mechanism of the motor. In our previous paper, we explained the general physics underneath the observed torque-speed curves with a simple two-state Fokker-Planck model. Here we further analyze this model. In this paper we show (1) the model predicts that the two components of the ion motive force can affect the motor dynamics differently, in agreement with the latest experiment by Lo et al.; (2) with explicit consideration of the stator spring, the model also explains the lack of dependence of the zero-load speed on stator number in the proton motor, recently observed by Yuan and Berg; (3) the model reproduces the stepping behavior of the motor even with the existence of the stator springs and predicts the dwelling time distribution. Predicted stepping behavior of motors with two stators is discussed, and we suggest future experimental verification.
The Dynamically Extended Mind -- A Minimal Modeling Case Study
Tom Froese; Carlos Gershenson; David A. Rosenblueth
2013-05-08T23:59:59.000Z
The extended mind hypothesis has stimulated much interest in cognitive science. However, its core claim, i.e. that the process of cognition can extend beyond the brain via the body and into the environment, has been heavily criticized. A prominent critique of this claim holds that when some part of the world is coupled to a cognitive system this does not necessarily entail that the part is also constitutive of that cognitive system. This critique is known as the "coupling-constitution fallacy". In this paper we respond to this reductionist challenge by using an evolutionary robotics approach to create a minimal model of two acoustically coupled agents. We demonstrate how the interaction process as a whole has properties that cannot be reduced to the contributions of the isolated agents. We also show that the neural dynamics of the coupled agents has formal properties that are inherently impossible for those neural networks in isolation. By keeping the complexity of the model to an absolute minimum, we are able to illustrate how the coupling-constitution fallacy is in fact based on an inadequate understanding of the constitutive role of nonlinear interactions in dynamical systems theory.
Chiral transition in a strong magnetic background
Eduardo S. Fraga; Ana Jlia Mizher
2008-04-09T23:59:59.000Z
The presence of a strong magnetic background can modify the nature and the dynamics of the chiral phase transition at finite temperature. We compute the modified effective potential in the linear sigma model with quarks to one loop in the $\\bar{MS}$ scheme for $N_{f}=2$. For fields $eB\\sim 5 m_{\\pi}^{2}$ and larger a crossover is turned into a weak first-order transition. We discuss possible implications for non-central heavy ion collisions at RHIC and LHC, and for the primordial QCD transition.
Modeling the Dynamic Behavior of a Single Pile in Dry Sand using a new p-y Material Model
Choi, JungIn; Brandenberg, Scott J; Kim, MyoungMo
2013-01-01T23:59:59.000Z
of dynamic pile behavior by centrifuge tests consideringof KOCED geotechnical centrifuge and its shear wave velocitysurface plasticity theory. Centrifuge model data analyzed
Toward a mechanistic modeling of nitrogen limitation on vegetation dynamics
Xu, Chonggang [Los Alamos National Laboratory (LANL); Fisher, Rosie [National Center for Atmospheric Research (NCAR); Wullschleger, Stan D [ORNL; Wilson, Cathy [Los Alamos National Laboratory (LANL); Cai, Michael [Los Alamos National Laboratory (LANL); McDowell, Nathan [Los Alamos National Laboratory (LANL)
2012-01-01T23:59:59.000Z
Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO{sub 2} concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO{sub 2} concentration, temperature, and radiation when evaluated against published data of V{sub c,max} (maximum carboxylation rate) and J{sub max} (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO{sub 2} concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks to climate in Earth system models.
Kuramoto dynamics in Hamiltonian systems
Dirk Witthaut; Marc Timme
2013-05-08T23:59:59.000Z
The Kuramoto model constitutes a paradigmatic model for the dissipative collective dynamics of coupled oscillators, characterizing in particular the emergence of synchrony. Here we present a classical Hamiltonian (and thus conservative) system with 2N state variables that in its action-angle representation exactly yields Kuramoto dynamics on N-dimensional invariant manifolds. We show that the synchronization transition on a Kuramoto manifold emerges where the transverse Hamiltonian action dynamics becomes unstable. The uncovered Kuramoto dynamics in Hamiltonian systems thus distinctly links dissipative to conservative dynamics.
Cuntz, M.; Roy, D.; Musielak, Z. E., E-mail: cuntz@uta.ed, E-mail: dipanjan.roy@etumel.univmed.f, E-mail: zmusielak@uta.ed [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)
2009-11-20T23:59:59.000Z
A significant controversy regarding the climate history of the Earth and its relationship to the development of complex life forms concerns the rise of oxygen in the early Earth's atmosphere. Geological records show that this rise occurred about 2.4 Gyr ago, when the atmospheric oxygen increased from less than 10{sup -5} present atmospheric level (PAL) to more than 0.01 PAL and possibly above 0.1 PAL. However, there is a debate whether this rise happened relatively smoothly or with well-pronounced ups and downs (the Yoyo model). In our study, we explore a simplified atmospheric chemical system consisting of oxygen, methane, and carbon that is driven by the sudden decline of the net input of reductants to the surface as previously considered by Goldblatt et al. Based on the transition stability analysis for the system equations, constituting a set of non-autonomous and non-linear differential equations, as well as the inspection of the Lyapunov exponents, it is found that the equations do not exhibit chaotic behavior. In addition, the rise of oxygen occurs relative smoothly, possibly with minor bumps (within a factor of 1.2), but without major jumps. This result clearly argues against the Yoyo model in agreement with recent geological findings.
MODEST: modeling stellar evolution and (hydro)dynamics
Piet Hut
2003-09-15T23:59:59.000Z
Simulations of dense stellar systems currently face two major hurdles, one astrophysical and one computational. The astrophysical problem lies in the fact that several major stages in binary evolution, such as common envelope evolution, are still poorly understood. The best we can do in these cases is to parametrize our ignorance, in a way that is reminiscent of the introduction of a mixing length to describe convection in a single star, or an alpha parameter in modeling an accretion disk. The hope is that by modeling a whole star cluster in great detail, and comparing the results to the wealth of observational data currently available, we will be able to constrain the parameters that capture the unknown physics. The computational problem is one of composition: while we have accurate computer codes for modeling stellar dynamics, stellar hydrodynamics, and stellar evolution, we currently have no good way to put all this knowledge together in a single software environment. A year ago, a loosely-knit organization was founded to address these problems, MODEST for MOdeling DEnse STellar systems, with nine working groups and a series of meetings that are held every half year. This report reviews the first year of this initiative. Much more detail can be found on the MODEST web site http://www.manybody.org/modest.html .
VISION -- A Dynamic Model of the Nuclear Fuel Cycle
J. J. Jacobson; A. M. Yacout; S. J. Piet; D. E. Shropshire; G. E. Matthern
2006-02-01T23:59:59.000Z
The Advanced Fuel Cycle Initiatives (AFCI) fundamental objective is to provide technology options that if implemented would enable long-term growth of nuclear power while improving sustainability and energy security. The AFCI organization structure consists of four areas; Systems Analysis, Fuels, Separations and Transmutations. The Systems Analysis Working Group is tasked with bridging the program technical areas and providing the models, tools, and analyses required to assess the feasibility of design and deployment options and inform key decision makers. An integral part of the Systems Analysis tool set is the development of a system level model that can be used to examine the implications of the different mixes of reactors, implications of fuel reprocessing, impact of deployment technologies, as well as potential exit or off ramp approaches to phase out technologies, waste management issues and long-term repository needs. The Verifiable Fuel Cycle Simulation Model (VISION) is a computer-based simulation model that allows performing dynamic simulations of fuel cycles to quantify infrastructure requirements and identify key trade-offs between alternatives. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies.
Dynamic Code Overlay of SDF-Modeled Programs on Low-end Embedded Systems
Ha, Soonhoi
Dynamic Code Overlay of SDF-Modeled Programs on Low-end Embedded Systems Hae-woo Park Kyoungjoo Oh of synchronous data-flow (SDF) modeled program for low-end embedded systems which lack MMU- support-program code, dynamic loader and linker script files from the given SDF- modeled blocks and schematic, so we
Dynamic Friction Models for Longitudinal Road/Tire Interaction: Theoretical Advances
Tsiotras, Panagiotis
Dynamic Friction Models for Longitudinal Road/Tire Interaction: Theoretical Advances C. Canudas we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled-point friction problems, called the LuGre model [1]. By assuming a con- tact patch between the tire
Object-oriented Dynamics Modeling for Legged Robot Trajectory Optimization and Control
Stryk, Oskar von
Object-oriented Dynamics Modeling for Legged Robot Trajectory Optimization and Control Robert. To facilitate the investigation of new concepts of nonlinear model-based optimization and control methods also-level specification of multibody dynamics models using component libraries serves as a basis for generation
Technical Note Comparing Dynamic Causal Models using AIC, BIC and Free Energy
Penny, Will
Technical Note Comparing Dynamic Causal Models using AIC, BIC and Free Energy W.D. Penny Wellcome) and Dynamic Causal Models (DCMs). We find that the Free Energy has the best model selection ability, to instead score DCMs using the Free Energy (Friston et al., 2007a). However, until now there has been
Capacitive effect of cavitation in xylem conduits: results from a dynamic model
Mencuccini, Maurizio
Capacitive effect of cavitation in xylem conduits: results from a dynamic model TEEMU H?LTT?1. A dynamic model is presented that models xylem water potential, xylem sap flow and cavitation, taking; xylem transport. INTRODUCTION Xylem embolism formation by cavitation causes a decrease in plant
Nomura, K.; Vretenar, D. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Niksic, T. [Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Otsuka, T. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Shimizu, N. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2011-07-15T23:59:59.000Z
Microscopic energy density functionals have become a standard tool for nuclear structure calculations, providing an accurate global description of nuclear ground states and collective excitations. For spectroscopic applications, this framework has to be extended to account for collective correlations related to restoration of symmetries broken by the static mean field, and for fluctuations of collective variables. In this paper, we compare two approaches to five-dimensional quadrupole dynamics: the collective Hamiltonian for quadrupole vibrations and rotations and the interacting boson model (IBM). The two models are compared in a study of the evolution of nonaxial shapes in Pt isotopes. Starting from the binding energy surfaces of {sup 192,194,196}Pt, calculated with a microscopic energy density functional, we analyze the resulting low-energy collective spectra obtained from the collective Hamiltonian, and the corresponding IBM Hamiltonian. The calculated excitation spectra and transition probabilities for the ground-state bands and the {gamma}-vibration bands are compared to the corresponding sequences of experimental states.
K. Nomura; T. Niksic; T. Otsuka; N. Shimizu; D. Vretenar
2011-06-14T23:59:59.000Z
Microscopic energy density functionals (EDF) have become a standard tool for nuclear structure calculations, providing an accurate global description of nuclear ground states and collective excitations. For spectroscopic applications this framework has to be extended to account for collective correlations related to restoration of symmetries broken by the static mean field, and for fluctuations of collective variables. In this work we compare two approaches to five-dimensional quadrupole dynamics: the collective Hamiltonian for quadrupole vibrations and rotations, and the Interacting Boson Model. The two models are compared in a study of the evolution of non-axial shapes in Pt isotopes. Starting from the binding energy surfaces of $^{192,194,196}$Pt, calculated with a microscopic energy density functional, we analyze the resulting low-energy collective spectra obtained from the collective Hamiltonian, and the corresponding IBM-2 Hamiltonian. The calculated excitation spectra and transition probabilities for the ground-state bands and the $\\gamma$-vibration bands are compared to the corresponding sequences of experimental states.
Como, Giacomo
Automating efficiency-targeted approximations in modelling and simulation tools: dynamic decoupling (classical) efficiency-targeted approximation tech- niques, within a unified framework. Some application
Emerging disease dynamics in a model coupling within-host and ...
Xiuli Cen
2014-08-27T23:59:59.000Z
Aug 2, 2014 ... Immunological models consider the within-host dynamics independent of the interactions between hosts (e.g., De Leenheer and Smith, 2003;.
A model for coupling within-host and between-host dynamics in an ...
2011-12-20T23:59:59.000Z
Abstract Studies on the modeling of the coupled dy- namics of infectious diseases at both the population level (the epidemic process or between-host dynamics).
Microscale and mesoscale discrete models for dynamic fracture of structures built of brittle are derived either at microscale with random distribution of material properties or at a mesoscale
Meier, Sebastian B., E-mail: sebastian.meier@belectric.com, E-mail: wiebke.sarfert@siemens.com [Department of Materials Science VI: Materials for Electronics and Energy Technology, Friedrich-Alexander-University of Erlangen-Nuremberg, 91058 Erlangen (Germany); Siemens AG, Corporate Technology, CT RTC MAT IEC-DE, 91058 Erlangen (Germany); Hartmann, David; Sarfert, Wiebke, E-mail: sebastian.meier@belectric.com, E-mail: wiebke.sarfert@siemens.com [Siemens AG, Corporate Technology, CT RTC MAT IEC-DE, 91058 Erlangen (Germany); Winnacker, Albrecht [Department of Materials Science VI: Materials for Electronics and Energy Technology, Friedrich-Alexander-University of Erlangen-Nuremberg, 91058 Erlangen (Germany)
2014-09-14T23:59:59.000Z
Light-emitting electrochemical cells (LECs) have received increasing attention during recent years due to their simple architecture, based on solely air-stabile materials, and ease of manufacture in ambient atmosphere, using solution-based technologies. The LEC's active layer offers semiconducting, luminescent as well as ionic functionality resulting in device physical processes fundamentally different as compared with organic light-emitting diodes. During operation, electrical double layers (EDLs) form at the electrode interfaces as a consequence of ion accumulation and electrochemical doping sets in leading to the in situ development of a light-emitting p-i-n junction. In this paper, we comment on the use of impedance spectroscopy in combination with complex nonlinear squares fitting to derive key information about the latter events in thin-film ionic transition metal complex-based light-emitting electrochemical cells based on the model compound bis-2-phenylpyridine 6-phenyl-2,2?-bipyridine iridium(III) hexafluoridophosphate ([Ir(ppy){sub 2}(pbpy)][PF{sub 6}]). At operating voltages below the bandgap potential of the ionic complex used, we obtain the dielectric constant of the active layer, the conductivity of mobile ions, the transference numbers of electrons and ions, and the thickness of the EDLs, whereas the transient thickness of the p-i-n junction is determined at voltages above the bandgap potential. Most importantly, we find that charge transport is dominated by the ions when carrier injection from the electrodes is prohibited, that ion movement is limited by the presence of transverse internal interfaces and that the width of the intrinsic region constitutes almost 60% of the total active layer thickness in steady state at a low operating voltage.
EPR pairing dynamics in Hubbard model with resonant $U$
X. Z. Zhang; Z. Song
2015-04-28T23:59:59.000Z
We study the dynamics of the collision between two fermions in Hubbard model with on-site interaction strength $U$. The exact solution shows that the scattering matrix for two-wavepacket collision is separable into two independent parts, operating on spatial and spin degrees of freedom, respectively. The S-matrix for spin configuration is equivalent to that of Heisenberg-type pulsed interaction with the strength depending on $U$ and relative group velocity $\\upsilon _{r}$. This can be applied to create distant EPR pair, through a collision process for two fermions with opposite spins in the case of $\\left\\vert \\upsilon _{r}/U\\right\\vert =1$,\\ without the need for temporal control and measurement process. Multiple collision process for many particles is also discussed.
Some optical and dynamical phenomena in the Rindler model
E. Birsin; W. Hasse
2014-11-15T23:59:59.000Z
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.
Dynamic Markov bridges motivated by models of insider trading
Campi, Luciano; Danilova, Albina
2012-01-01T23:59:59.000Z
Given a Markovian Brownian martingale $Z$, we build a process $X$ which is a martingale in its own filtration and satisfies $X_1 = Z_1$. We call $X$ a dynamic bridge, because its terminal value $Z_1$ is not known in advance. We compute explicitly its semimartingale decomposition under both its own filtration $\\cF^X$ and the filtration $\\cF^{X,Z}$ jointly generated by $X$ and $Z$. Our construction is heavily based on parabolic PDE's and filtering techniques. As an application, we explicitly solve an equilibrium model with insider trading, that can be viewed as a non-Gaussian generalization of Back and Pedersen's \\cite{BP}, where insider's additional information evolves over time.
Tyre modelling for use in vehicle dynamics studies
Bakker, E.; Nyborg, L.; Pacejka, H.B.
1987-01-01T23:59:59.000Z
A new way of representing tyre data obtained from measurements in pure cornering and pure braking conditions has been developed in order to further improve the Dynamic Safety of vehicles. The method makes use of a formula with coefficients which describe some of the typifying quantities of a tyre, such as slip stiffnesses at zero slip and force and torque peak values. The formula is capable of describing the characteristics of side force, brake force and self aligning torque with great accuracy. This mathematical representation is limited to steady-state conditions during either pure cornering or pure braking and forms the basis for a model describing tyre behaviour during combined braking and cornering.
Dynamical modeling of the Deep Impact dust ejecta cloud
Tanyu Bonev; Nancy Ageorges; Stefano Bagnulo; Luis Barrera; Hermann B{}hnhardt; Olivier Hainaut; Emmanuel Jehin; Hans-Ullrich K{}ufl; Florian Kerber; Gaspare LoCurto; Jean Manfroid; Olivier Marco; Eric Pantin; Emanuela Pompei; Ivo Saviane; Fernando Selman; Chris Sterken; Heike Rauer; Gian Paolo Tozzi; Michael Weiler
2007-03-21T23:59:59.000Z
The collision of Deep Impact with comet 9P/Tempel 1 generated a bright cloud of dust which dissipated during several days after the impact. The brightness variations of this cloud and the changes of its position and shape are governed by the physical properties of the dust grains. We use a Monte Carlo model to describe the evolution of the post-impact dust plume. The results of our dynamical simulations are compared to the data obtained with FORS2, the FOcal Reducer and low dispersion Spectrograph for the VLT of the European Southern Observatory (ESO), to derive the particle size distribution and the total amount of material contained in the dust ejecta cloud.
Shear band dynamics from a mesoscopic modeling of plasticity
E. A. Jagla
2010-06-07T23:59:59.000Z
The ubiquitous appearance of regions of localized deformation (shear bands) in different kinds of disordered materials under shear is studied in the context of a mesoscopic model of plasticity. The model may or may not include relaxational (aging) effects. In the absence of relaxational effects the model displays a monotonously increasing dependence of stress on strain-rate, and stationary shear bands do not occur. However, in start up experiments transient (although long lived) shear bands occur, that widen without bound in time. I investigate this transient effect in detail, reproducing and explaining a t^1/2 law for the thickness increase of the shear band that has been obtained in atomistic numerical simulations. Relaxation produces a negative sloped region in the stress vs. strain-rate curve that stabilizes the formation of shear bands of a well defined width, which is a function of strain-rate. Simulations at very low strain-rates reveal a non-trivial stick-slip dynamics of very thin shear bands that has relevance in the study of seismic phenomena. In addition, other non-stationary processes, such as stop-and-go, or strain-rate inversion situations display a phenomenology that matches very well the results of recent experimental studies.
Creating dynamic equivalent PV circuit models with impedance spectroscopy for arc-fault modeling.
Johnson, Jay Dean; Kuszmaul, Scott S.; Strauch, Jason E.; Schoenwald, David Alan
2011-06-01T23:59:59.000Z
Article 690.11 in the 2011 National Electrical Code{reg_sign} (NEC{reg_sign}) requires new photovoltaic (PV) systems on or penetrating a building to include a listed arc fault protection device. Currently there is little experimental or empirical research into the behavior of the arcing frequencies through PV components despite the potential for modules and other PV components to filter or attenuate arcing signatures that could render the arc detector ineffective. To model AC arcing signal propagation along PV strings, the well-studied DC diode models were found to inadequately capture the behavior of high frequency arcing signals. Instead dynamic equivalent circuit models of PV modules were required to describe the impedance for alternating currents in modules. The nonlinearities present in PV cells resulting from irradiance, temperature, frequency, and bias voltage variations make modeling these systems challenging. Linearized dynamic equivalent circuits were created for multiple PV module manufacturers and module technologies. The equivalent resistances and capacitances for the modules were determined using impedance spectroscopy with no bias voltage and no irradiance. The equivalent circuit model was employed to evaluate modules having irradiance conditions that could not be measured directly with the instrumentation. Although there was a wide range of circuit component values, the complex impedance model does not predict filtering of arc fault frequencies in PV strings for any irradiance level. Experimental results with no irradiance agree with the model and show nearly no attenuation for 1 Hz to 100 kHz input frequencies.
Idealized test cases for the dynamical cores of Atmospheric General Circulation Models
Jablonowski, Christiane
Idealized test cases for the dynamical cores of Atmospheric General Circulation Models: A proposal) Ram Nair (NCAR) Mark Taylor (Sandia National Laboratory) May/29/2008 1 Idealized test cases for 3D dynamical cores This document describes the idealized dynamical core test cases that are proposed
Physica D 159 (2001) 3557 Wave group dynamics in weakly nonlinear long-wave models
Pelinovsky, Dmitry
Physica D 159 (2001) 3557 Wave group dynamics in weakly nonlinear long-wave models Roger Grimshawa Communicated by A.C. Newell Abstract The dynamics of wave groups is studied for long waves, using the framework reserved. Keywords: Wave group dynamics; Kortewegde Vries equation; Nonlinear Schr¨odinger equation 1
Shell Model Dynamics of HCl on the MgO(001) Surface Terrace Andreas Markmann,1
Markmann, Andreas
are then used to aid the analysis of MD calculations. After equilibrium dynamics, a sudden excitation of the OH of molecular dynamics using specially tailored laser fields. The reaction of hydrogen chloride moleculesShell Model Dynamics of HCl on the MgO(001) Surface Terrace Andreas Markmann,1 Jacob L. Gavartin,2
Adler, Joan
One-particle di#11;usional model to mimic some properties of glass transition. Sorkin A.V., Ivanov #15; Computer studies of glass transition #15; Model and simulations #15; Results #15; Conclusions 2 #12; Introduction In recent time many properties of glass transitions have been investigated
Application of Extended Kalman Filter Techniques for Dynamic Model Parameter Calibration
Huang, Zhenyu; Du, Pengwei; Kosterev, Dmitry; Yang, Bo
2009-07-26T23:59:59.000Z
Abstract -Phasor measurement has previously been used for sub-system model validation, which enables rigorous comparison of model simulation and recorded dynamics and facilitates identification of problematic model components. Recent work extends the sub-system model validation approach with a focus on how model parameters may be calibrated to match recorded dynamics. In this paper, a calibration method using Extended Kalman Filter (EKF) technique is proposed. This paper presents the formulation as well as case studies to show the validity of the EKF-based parameter calibration method. The proposed calibration method is expected to be a cost-effective means complementary to traditional equipment testing for improving dynamic model quality.
Melnik, Roderick
Phase transitions in shape memory alloys with hyperbolic heat conduction and differential are given. Keywords Phase transitions, Shape memory alloys, Hyperbolic heat conduction 1 Introduction One-called solidsolid phase transformations, in ``smart'' materials known as shape memory alloys (SMAs
Offner, Stella S. R. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Bisbas, Thomas G.; Viti, Serena [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6B (United Kingdom); Bell, Tom A., E-mail: stella.offner@yale.edu [Centro de Astrobiologia (CSIC-INTA), Carretera de Ajalvir, km 4, E-28850 Madrid (Spain)
2013-06-10T23:59:59.000Z
We use 3D-PDR, a three-dimensional astrochemistry code for modeling photodissociation regions (PDRs), to post-process hydrodynamic simulations of turbulent, star-forming clouds. We focus on the transition from atomic to molecular gas, with specific attention to the formation and distribution of H, C{sup +}, C, H{sub 2}, and CO. First, we demonstrate that the details of the cloud chemistry and our conclusions are insensitive to the simulation spatial resolution, to the resolution at the cloud edge, and to the ray angular resolution. We then investigate the effect of geometry and simulation parameters on chemical abundances and find weak dependence on cloud morphology as dictated by gravity and turbulent Mach number. For a uniform external radiation field, we find similar distributions to those derived using a one-dimensional PDR code. However, we demonstrate that a three-dimensional treatment is necessary for a spatially varying external field, and we caution against using one-dimensional treatments for non-symmetric problems. We compare our results with the work of Glover et al., who self-consistently followed the time evolution of molecule formation in hydrodynamic simulations using a reduced chemical network. In general, we find good agreement with this in situ approach for C and CO abundances. However, the temperature and H{sub 2} abundances are discrepant in the boundary regions (A{sub v} {<=} 5), which is due to the different number of rays used by the two approaches.
Georgia, University of
Models, Modeling Dynamic Systems, DOI 10.1007/978-1-4614-1257-1_7, © Springer Science+Business Media, LLC, these targets should represent the most efficient use of limited resources, especially given that resource managers need to balance multiple, often complex issues (Reed et al. 2009). Population models can often aid
Transition dynamics for Mu acceptor states in Si{sub 1x}Ge{sub x} alloys
Jayarathna, G.; Lichti, R. L.; Mengyan, P. W.; Baker, B. B. [Texas Tech University, Lubbock, TX 79409-1051 (United States); Celebi, Y. G. [Istanbul University, Istanbul (Turkey); Carroll, B. R. [Arkansas State University, Jonesboro, AR 72410 (United States); Yonenaga, I. [Institute of Materials Research, Tohoku University (Japan)
2014-02-21T23:59:59.000Z
We use the longitudinal field muon spin relaxation technique to observe charge-state and site-change transitions of muonium in Si{sub 1x}Ge{sub x} alloys. In this project, we examine the temperature and magnetic field dependences of the relaxation rates for Si{sub 1x}Ge{sub x} samples (x = 0.77, 0.81, and 0.84), in the composition range where the acceptor level lies within the band gap. This study particularly focuses on the relaxation rates for Si{sub 0.19}Ge{sub 0.81} to identify various cyclic charge-state and site-change processes as a function of both temperature and magnetic field. We extract the paramagnetic hyperfine constant and the relevant transition rate parameters for site changes and charge-state transitions involving Mu acceptor states for this sample. At small x, a site change dominates the transition out of the neutral T-site acceptor state, while in higher Ge content alloys hole ionization becomes the dominant transition out of the Mu{sub T}{sup 0}.
Adaptive Optimal Feedback Control with Learned Internal Dynamics Models
Mitrovic, Djordje; Klanke, Stefan; Vijayakumar, Sethu
2010-01-01T23:59:59.000Z
, have focused on the case of non-linear, but still analytically available, dynamics. For realistic control systems, however, the dynamics may often be unknown, difficult to estimate, or subject to frequent systematic changes. In this chapter, we combine...
A spatially structured metapopulation model with patch dynamics
2007-08-22T23:59:59.000Z
Sep 30, 2005 ... creation) and metapopulation dynamics (patch colonization and extinction). ... genetic structure (Gaines and Lyons, 1997), and commu-.
Stochastic model for aerodynamic force dynamics on wind turbine blades in unsteady wind inflow
Luhur, Muhammad Ramzan; Khn, Martin; Wchter, Matthias
2015-01-01T23:59:59.000Z
The paper presents a stochastic approach to estimate the aerodynamic forces with local dynamics on wind turbine blades in unsteady wind inflow. This is done by integrating a stochastic model of lift and drag dynamics for an airfoil into the aerodynamic simulation software AeroDyn. The model is added as an alternative to the static table lookup approach in blade element momentum (BEM) wake model used by AeroDyn. The stochastic forces are obtained for a rotor blade element using full field turbulence simulated wind data input and compared with the classical BEM and dynamic stall models for identical conditions. The comparison shows that the stochastic model generates additional extended dynamic response in terms of local force fluctuations. Further, the comparison of statistics between the classical BEM, dynamic stall and stochastic models' results in terms of their increment probability density functions gives consistent results.
Ultrafast Structural Dynamics in Combustion Relevant Model Systems
Weber, Peter M. [Brown University
2014-03-31T23:59:59.000Z
The research project explored the time resolved structural dynamics of important model reaction system using an array of novel methods that were developed specifically for this purpose. They include time resolved electron diffraction, time resolved relativistic electron diffraction, and time resolved Rydberg fingerprint spectroscopy. Toward the end of the funding period, we also developed time-resolved x-ray diffraction, which uses ultrafast x-ray pulses at LCLS. Those experiments are just now blossoming, as the funding period expired. In the following, the time resolved Rydberg Fingerprint Spectroscopy is discussed in some detail, as it has been a very productive method. The binding energy of an electron in a Rydberg state, that is, the energy difference between the Rydberg level and the ground state of the molecular ion, has been found to be a uniquely powerful tool to characterize the molecular structure. To rationalize the structure sensitivity we invoke a picture from electron diffraction: when it passes the molecular ion core, the Rydberg electron experiences a phase shift compared to an electron in a hydrogen atom. This phase shift requires an adjustment of the binding energy of the electron, which is measurable. As in electron diffraction, the phase shift depends on the molecular, geometrical structure, so that a measurement of the electron binding energy can be interpreted as a measurement of the molecules structure. Building on this insight, we have developed a structurally sensitive spectroscopy: the molecule is first elevated to the Rydberg state, and the binding energy is then measured using photoelectron spectroscopy. The molecules structure is read out as the binding energy spectrum. Since the photoionization can be done with ultrafast laser pulses, the technique is inherently capable of a time resolution in the femtosecond regime. For the purpose of identifying the structures of molecules during chemical reactions, and for the analysis of molecular species in the hot environments of combustion processes, there are several features that make the Rydberg ionization spectroscopy uniquely useful. First, the Rydberg electrons orbit is quite large and covers the entire molecule for most molecular structures of combustion interest. Secondly, the ionization does not change vibrational quantum numbers, so that even complicated and large molecules can be observed with fairly well resolved spectra. In fact, the spectroscopy is blind to vibrational excitation of the molecule. This has the interesting consequence for the study of chemical dynamics, where the molecules are invariably very energetic, that the molecular structures are observed unobstructed by the vibrational congestion that dominates other spectroscopies. This implies also that, as a tool to probe the time-dependent structural dynamics of chemically interesting molecules, Rydberg spectroscopy may well be better suited than electron or x-ray diffraction. With recent progress in calculating Rydberg binding energy spectra, we are approaching the point where the method can be evolved into a structure determination method. To implement the Rydberg ionization spectroscopy we use a molecular beam based, time-resolved pump-probe multi-photon ionization/photoelectron scheme in which a first laser pulse excites the molecule to a Rydberg state, and a probe pulse ionizes the molecule. A time-of-flight detector measures the kinetic energy spectrum of the photoelectrons. The photoelectron spectrum directly provides the binding energy of the electron, and thereby reveals the molecules time-dependent structural fingerprint. Only the duration of the laser pulses limits the time resolution. With a new laser system, we have now reached time resolutions better than 100 fs, although very deep UV wavelengths (down to 190 nm) have slightly longer instrument functions. The structural dynamics of molecules in Rydberg-excited states is obtained by delaying the probe ionization photon from the pump photon; the structural dynamics of molecules in their ground state or e
Accessibility-based transit planning
Busby, Jeffrey R
2004-01-01T23:59:59.000Z
A method for evaluating transit planning proposals using accessibility metrics is advanced in this research. A transit-accessibility model is developed intended for use by in-house transit agency planning staff as a ...
Networking technology adoption : system dynamics modeling of fiber-to-the-home
Kelic, Andjelka, 1972-
2005-01-01T23:59:59.000Z
A system dynamics model is developed and run to study the adoption of fiber-to-the-home as a residential broadband technology. Communities that currently do not have broadband in the United States are modeled. This case ...
age-structured dynamical models: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
does not migrate. Le, Thuc Manh; Van Minh, Nguyen 2010-01-01 36 Galactic Nonlinear Dynamic Model Mathematical Physics (arXiv) Summary: We develop a model for spiral galaxies...
Optimal foreign borrowing in a multisector dynamic equilibrium model for Brazil
Tourinho, Octv?io A. F.
1985-01-01T23:59:59.000Z
This paper shows how a dynamic multisector equilibrium model can be formulated to be able to analyze the optimal borrowing policy of a developing country. It also describes how a non-linear programming model with the ...
DYNAMIC MODELING AND CONTROL OF REACTIVE DISTILLATION FOR HYDROGENATION OF BENZENE
Aluko, Obanifemi
2010-01-16T23:59:59.000Z
This work presents a modeling and control study of a reactive distillation column used for hydrogenation of benzene. A steady state and a dynamic model have been developed to investigate control structures for the column. The most important aspects...
Multiple Model Robust Dynamic Programming Eric C. Whitman and Christopher G. Atkeson
-- Modeling error is a common problem for model- based control techniques. We present multiple model dynamic programming (MMDP) as a method to generate controllers that are robust to modeling error. Our method generates controllers that are approximately optimal for a collection of models, thereby forcing the controller
Protecting the African elephant: A dynamic bioeconomic model of ivory trade
Protecting the African elephant: A dynamic bioeconomic model of ivory trade G. Cornelis van Kooten Accepted 25 May 2008 Available online 7 July 2008 Keywords: Economics Elephant conservation Ivory trade ban Mathematical programming Trade quota A B S T R A C T A dynamic bioeconomic model of ivory trade is used
STOCHASTIC COMPUTATIONAL DYNAMICAL MODEL OF UNCERTAIN STRUCTURE COUPLED WITH AN INSULATION LAYER
Boyer, Edmond
STOCHASTIC COMPUTATIONAL DYNAMICAL MODEL OF UNCERTAIN STRUCTURE COUPLED WITH AN INSULATION LAYER the effect of insulation layers in complex dynamical systems for low- and medium-frequency ranges such as car booming noise analysis, one introduces a sim- plified stochastic model of insulation layers based
A Numerical Model for the Dynamic Simulation of a Recirculation Single-Effect Absorption Chiller
Paris-Sud XI, Université de
A Numerical Model for the Dynamic Simulation of a Recirculation Single- Effect Absorption Chiller A dynamic model for the simulation of a new single-effect water/lithium bromide absorption chiller is developed. The chiller is driven by two distinct heat sources, includes a custom integrated falling film
Dynamic Friction Models for Longitudinal Road/Tire Interaction: Experimental Results
Tsiotras, Panagiotis
Dynamic Friction Models for Longitudinal Road/Tire Interaction: Experimental Results C. Canudas dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles is val- idated via experiments with an actual passenger vehicle. Contrary to common static friction/slip maps
Bierlaire, Michel
A differentiable dynamic network loading model that yields queue length distributions and accounts, this is so because the kinematic wave model (KWM), the mainstay of traffic flow theory, only applies for spillback Carolina Osorio Gunnar Fl¨otter¨od Michel Bierlaire Abstract We derive a dynamic network
ROLE OF VEHICLE DYNAMIC MODELING FIDELITY WITH HAPTIC COLLABORATION IN STEER BY WIRE
Krovi, Venkat
ROLE OF VEHICLE DYNAMIC MODELING FIDELITY WITH HAPTIC COLLABORATION IN STEER BY WIRE SYSTEMS control back to the driver. Candidate solutions for mimicking the steering feel have ranged from direct torque prediction schemes based on mathematical dynamics models (of tire-road, suspension, power-steering
Dynamic model failure tests of dam structures Dalian University of Technology, Dalian 116024, China
Spencer Jr., B.F.
Dynamic model failure tests of dam structures Gao Lin Dalian University of Technology, Dalian failure tests of a number of concrete gravity dams, concrete arch dams and embankment dams have been index for the safety assessment of concrete dams and is predicted through dynamic model failure tests
NUMERICAL MODELING OF SHOCK-INDUCED DAMAGE FOR GRANITE UNDER DYNAMIC LOADING
Stewart, Sarah T.
NUMERICAL MODELING OF SHOCK-INDUCED DAMAGE FOR GRANITE UNDER DYNAMIC LOADING H. A. Ai1 , T. J beneath impact crater in granite. Model constants are determined either directly from static uniaxial from Century Dynamics to simulate the shock-induced damage in granite targets impacted by projectiles
Gupta, Rajesh
A Model Checking Approach to Evaluating System Level Dynamic Power Management Policies for Embedded, and laptops, controlling power dissipation is an important system design issue [2]. This is either because enforced at the system level. In [3], a system modeling ap- proach for dynamic power management strategy
AN IMPROVED DYNAMIC MODEL FOR THE STUDY OF A FLEXIBLE PAVEMENT
Avignon et des Pays de Vaucluse, Universit de
AN IMPROVED DYNAMIC MODEL FOR THE STUDY OF A FLEXIBLE PAVEMENT A. El Ayadi 1 , B. Picoux 1 , G to study a Falling Weight Deectometer test conducted on a exible pavement. These dynamic models take with in situ measurements recorded on an instrumented pavement; such a comparison has indicated the importance
Dynamic Versus Steady-State Modeling of FACTS Controllers in Transmission Congestion
Cañizares, Claudio A.
benchmark system is used to illustrate and compare the effect on locational marginal prices and transmission marginal prices obtained from stability-constrained auction models when dynamic and steady state FACTS discusses the effect on transmission congestion management and pricing of dynamic and steady- state models
A Dynamic Model for Phase Transformations in 3D Samples of Shape Memory Alloys
Melnik, Roderick
A Dynamic Model for Phase Transformations in 3D Samples of Shape Memory Alloys D.R. Mahapatra and R Introduction Modelling of dynamics of phase transformations (PT) in Shape Memory Al- loys (SMAs) under which assist the researchers in designing new materials and devices by harnessing the shape memory
Nagurney, Anna
An Efficiency Measure for Dynamic Networks Modeled as Evolutionary Variational Inequalities propose an efficiency/performance measure for dynamic net- works, which have been modeled as evolutionary and their rankings. We provide both continuous time and discrete time versions of the efficiency measure. We
A model for dynamic chance constraints in hydro power reservoir management
Rmisch, Werner
A model for dynamic chance constraints in hydro power reservoir management L. Andrieu , R. Henrion In this paper, a model for (joint) dynamic chance constraints is proposed and ap- plied to an optimization for two and three stages. 1 Introduction A conventional optimization problem under chance constraints
Dynamic Optimization in Continuous-Time Economic Models (A Guide for the Perplexed)
Sadoulet, Elisabeth
Dynamic Optimization in Continuous-Time Economic Models (A Guide for the Perplexed) Maurice, continuous-time modeling allows application of a powerful mathematical tool, the theory of optimal dynamic control. The basic idea of optimal control theory is easy to grasp-- indeed it follows from elementary
A Groundwater Dynamic Simulation Model: Application to the Upper San Pedro Basin
Fay, Noah
A Groundwater Dynamic Simulation Model: Application to the Upper San Pedro Basin Report Prepared by using tools such as tracers to determine groundwater travel times and this dynamic simulation modeling Initiative Fund, Water Sustainability Graduate Fellowship Program 2004/2005 #12;2 Introduction Located
Evaluation of the Structure of Levee Transitions on Wave Runup and Overtopping by Physical Modeling
Oaks, Drake Benjamin
2011-08-08T23:59:59.000Z
traditional overtopping techniques have predicted. The runup values and floodwall wave heights tend to show potential problematic areas and mimic the variation of overtopping along the levee transition. Under the design conditions tested, extreme overtopping...
Dynamical aspects of the plane-wave matrix model at finite temperature
Naoyuki Kawahara; Jun Nishimura; Kentaroh Yoshida
2006-04-25T23:59:59.000Z
We study dynamical aspects of the plane-wave matrix model at finite temperature. One-loop calculation around general classical vacua is performed using the background field method, and the integration over the gauge field moduli is carried out both analytically and numerically. In addition to the trivial vacuum, which corresponds to a single M5-brane at zero temperature, we consider general static fuzzy-sphere type configurations. They are all 1/2 BPS, and hence degenerate at zero temperature due to supersymmetry. This degeneracy is resolved, however, at finite temperature, and we identify the configuration that gives the smallest free energy at each temperature. The Hagedorn transition in each vacuum is studied by using the eigenvalue density method for the gauge field moduli, and the free energy as well as the Polyakov line is obtained analytically near the critical point. This reveals the existence of fuzzy sphere phases, which may correspond to the plasma-ball phases in N=4 SU(\\infty) SYM on S^1 X S^3. We also perform Monte Carlo simulation to integrate over the gauge field moduli. While this confirms the validity of the analytic results near the critical point, it also shows that the trivial vacuum gives the smallest free energy throughout the high temperature regime.
Coupled thermodynamic-dynamic semi-analytical model of Free Piston Stirling engines
Formosa, Fabien
2013-01-01T23:59:59.000Z
The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standard...
Froyland, Gary
2012-01-01T23:59:59.000Z
grains for lateral support to maintain and find new stable states. However, the dynamics associated by buckling correspond to rearrangements among, or loss of, contacts which break the three-cycle topology. DOI
Integrated dynamic landscape analysis and modeling system (IDLAMS) : installation manual.
Li, Z.; Majerus, K. A.; Sundell, R. C.; Sydelko, P. J.; Vogt, M. C.
1999-02-24T23:59:59.000Z
The Integrated Dynamic Landscape Analysis and Modeling System (IDLAMS) is a prototype, integrated land management technology developed through a joint effort between Argonne National Laboratory (ANL) and the US Army Corps of Engineers Construction Engineering Research Laboratories (USACERL). Dr. Ronald C. Sundell, Ms. Pamela J. Sydelko, and Ms. Kimberly A. Majerus were the principal investigators (PIs) for this project. Dr. Zhian Li was the primary software developer. Dr. Jeffrey M. Keisler, Mr. Christopher M. Klaus, and Mr. Michael C. Vogt developed the decision analysis component of this project. It was developed with funding support from the Strategic Environmental Research and Development Program (SERDP), a land/environmental stewardship research program with participation from the US Department of Defense (DoD), the US Department of Energy (DOE), and the US Environmental Protection Agency (EPA). IDLAMS predicts land conditions (e.g., vegetation, wildlife habitats, and erosion status) by simulating changes in military land ecosystems for given training intensities and land management practices. It can be used by military land managers to help predict the future ecological condition for a given land use based on land management scenarios of various levels of training intensity. It also can be used as a tool to help land managers compare different land management practices and further determine a set of land management activities and prescriptions that best suit the needs of a specific military installation.
Integrated dynamic landscape analysis and modeling system (IDLAMS) : programmer's manual.
Klaus, C. M.; Li, Z.; Majerus, K. A.; Sundell, R. C.; Sydelko, P. J.; Vogt, M. C.
1999-02-24T23:59:59.000Z
The Integrated Dynamic Landscape Analysis and Modeling System (IDLAMS) is a prototype, integrated land management technology developed through a joint effort between Argonne National Laboratory (ANL) and the US Army Corps of Engineers Construction Engineering Research Laboratories (USACERL). Dr. Ronald C. Sundell, Ms. Pamela J. Sydelko, and Ms. Kimberly A. Majerus were the principal investigators (PIs) for this project. Dr. Zhian Li was the primary software developer. Dr. Jeffrey M. Keisler, Mr. Christopher M. Klaus, and Mr. Michael C. Vogt developed the decision analysis component of this project. It was developed with funding support from the Strategic Environmental Research and Development Program (SERDP), a land/environmental stewardship research program with participation from the US Department of Defense (DoD), the US Department of Energy (DOE), and the US Environmental Protection Agency (EPA). IDLAMS predicts land conditions (e.g., vegetation, wildlife habitats, and erosion status) by simulating changes in military land ecosystems for given training intensities and land management practices. It can be used by military land managers to help predict the future ecological condition for a given land use based on land management scenarios of various levels of training intensity. It also can be used as a tool to help land managers compare different land management practices and further determine a set of land management activities and prescriptions that best suit the needs of a specific military installation.
The modeling of aerosol dynamics during degraded core events
Clausse, A.; Lahey, R.T. Jr.
1989-01-01T23:59:59.000Z
There is substantial interest in developing simple, yet accurate, models for the prediction of aerosol dynamics during degraded core events. The exact aerosol transport equation is given by {partial derivative}n(v,t)/{partial derivative}t = 1/2 {integral}{sub 0}{sup {infinity}} K(u,v {minus} u)n(u,t)n(v {minus} u,t)du {minus} {integral}{sub 0}{sup {infinity}} K(u,v)n(v,t)n(u,t)du {minus} n(v,t)c(v)/h + n{sub p}(v), where n(v,t) is the particle size density distribution function. The kernel, K(v,u), is related to the frequency of coagulation between aerosol particles of volume u and v, and the quantity c(v) is the deposition velocity. The quantity h is the effective height for deposition of aerosol; it is the volume of the aerosol cloud divided by the projected horizontal area A. Finally, the term n{sub p} (v) is the source rate of aerosol. Evaluation of the above equation is discussed.
Sandia National Laboratories: model of solar purchase dynamics
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of solar purchase dynamics Price Premiums for Solar Home Sales On February 25, 2015, in Energy, News, News & Events, Partnership, Photovoltaic, Renewable Energy, Solar, Systems...
Dynamics of an age-structured metapopulation model
2005-10-28T23:59:59.000Z
address the temporal dynamics that characterize local popu- lations in ... this metapopulation framework, two structures have emerged as being critical in the...
Springtime transitions of NO2, CO, and O3 over North America: Model evaluation and analysis
Chance, Kelly
. The solar input energizes photochemical and meteorological process- es directly by increasing radical and dynamical conditions of the atmosphere. These changes are driven primarily by increasing solar insolation
Paudel, Subodh; Elmtiri, Mohamed; Kling, Wil L; Corre, Olivier Le; Lacarriere, Bruno
2014-01-01T23:59:59.000Z
R. Satake, Prediction of energy demands using neural networkof Building Heating Energy Demand Using Artificial Neuralknow energy flows and energy demand of the buildings for the
Paudel, Subodh; Elmtiri, Mohamed; Kling, Wil L; Corre, Olivier Le; Lacarriere, Bruno
2014-01-01T23:59:59.000Z
simulation and artificial neural network for forecastingloads using artificial neural networks, 2001 World Congress,consumption by using artificial neural network, Advances in
Stefanopoulou, Anna
MODEL-BASED FEEDBACK CONTROL FOR AN AUTOMATED TRANSFER OUT OF SI OPERATION DURING SI TO HCCI for the transition between spark ignition (SI) and homo- geneous charge compression ignition (HCCI) combustion modes by approaching the transfer out of SI operation during the SI into HCCI transition in a closed-loop control
arterial phase dynamic: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of PVT systems. In particular, we establish a new time-dependent Ginzburg-Landau model, whose dynamic transition analysis is carried out. It is worth pointing out that the...
BIOMECHANICAL ANALYSIS OF TWO SIMPLE DYNAMICAL MODELS FOR THE HUMAN GAIT
Llanos, Diego R.
and expenditure energy for the human body in normal walking models. Both models allow us to adapt a vector the adaptability of the subject to the environment in a reactive way . The high complexity of biomechanical modelsBIOMECHANICAL ANALYSIS OF TWO SIMPLE DYNAMICAL MODELS FOR THE HUMAN GAIT J.Finat1 , F.Montoya2
Rate models with delays and the dynamics of large networks of spiking neurons
Roxin, Alex
1 Rate models with delays and the dynamics of large networks of spiking neurons Alex Roxin, Nicolas in a reduced rate model provided that the interactions are delayed. 1. Introduction Simplified models of large transformation through a sigmoidal input-output transfer function. Network models of spiking neurons can
1 Abstract--Eventually, prediction of transformer thermal performance for dynamic loading will be made using models distilled from measure data, rather than models derived from transformer heat for measuring the acceptability of transformer thermal models. For a model to be acceptable, it must have
A Business Model Framework for Dynamic Spectrum Access in Cognitive Networks
Ha, Dong S.
A Business Model Framework for Dynamic Spectrum Access in Cognitive Networks Nikhil Kelkar, Dr implement these technologies and still profit from them? III. FUNDAMENTAL MODEL The business model which we a multi-parameter approach by defining four levels on which everyday business models operate. Value
Xing-Hai Zhang; Su-Peng Kou
2012-05-30T23:59:59.000Z
In this paper, we studied a generalized Bose-Hubbard model on a checkerboard lattice with topologically nontrivial flat-band. We used mean-field method to decouple the model Hamiltonian and obtained phase diagram by Landau theory of second-order phase transition. We further calculate the energy gap and the dispersion of quasi-particle or quasi-hole in Mott insulator state and found that in strong interaction limit the quasi-particles or the quasi-holes also have flat bands.
Improved Modeling of Transition Metals, Applications to Catalysis and Technetium Chemistry
Cundari, T. R.
2004-03-05T23:59:59.000Z
There is considerable impetus for identification of aqueous OM catalysts as water is the ultimate ''green'' solvent. In collaboration with researchers at Ames Lab, we investigated effective fragment and Monte Carlo techniques for aqueous-phase hydroformylation (HyF). The Rh of the HyF catalyst is weakly aquated, in contrast to the hydride of the Rh-H bond. As the insertion of the olefin C=C into Rh-H determines the linear-to-branched aldehyde ratio, it is reasonable to infer that solvent plays an important role in regiochemistry. Studies on aqueous-phase organometallic catalysis were complemented in studies of the gas-phase reaction. A Rh-carbonyl-phosphine catalyst was investigated. Two of the most important implications of this research include (a) pseudorotation among five-coordinate intermediates is significant in HyF, and (b) CO insertion is the rate-determining step. The latter is in contrast to experimental deductions, highlighting the need for more accurate modeling. To this end, we undertook studies of (a) experimentally relevant PR{sub 3} co-ligands (PMe{sub 3}, PPh{sub 3}, P(p-PhSO{sub 3{sup -}}){sub 3}, etc.), and (b) HyF of propene. For the propylene research, simulations indicated that the linear: branched aldehyde ratio (linear is more desirable) is determined by thermodynamic discrimination of two distinct pathways. Other projects include a theory-experiment study of C-H activation by early transition metal systems, which establishes that weakly-bound adducts play a key role in activity selectivity. By extension, more selective catalysts for functionalization of methane (major component of natural gas) will require better understanding of these adducts, which are greatly affected by steric interactions with the ligands. In the de novo design of Tc complexes, we constructed (and are now testing) a coupled quantum mechanics-molecular mechanics protocol. Initial research shows it to be capable of accurately predicting structure ''from scratch.'' Challenges include conformational, geometric, coordination, spin, and particularly linkage (e.g., Tc-SCN versus Tc-NCS) isomerism. In general, our protocol can rapidly (<1 day with desktop software/hardware) predict the structure of diverse Tc complexes with an accuracy commensurate to organics. Our de novo strategy is also being used to investigate tris-pyrazolyl borate (Tp) complexes. Data suggests a fundamental difference in methane activation between TpRe and related CpRe complexes. Furthermore, Tp is a more electronically ''flexible'' platform for catalysts modification than Cp.
JACKSON VL
2011-08-31T23:59:59.000Z
The primary purpose of the tank mixing and sampling demonstration program is to mitigate the technical risks associated with the ability of the Hanford tank farm delivery and celtification systems to measure and deliver a uniformly mixed high-level waste (HLW) feed to the Waste Treatment and Immobilization Plant (WTP) Uniform feed to the WTP is a requirement of 24590-WTP-ICD-MG-01-019, ICD-19 - Interface Control Document for Waste Feed, although the exact definition of uniform is evolving in this context. Computational Fluid Dynamics (CFD) modeling has been used to assist in evaluating scaleup issues, study operational parameters, and predict mixing performance at full-scale.
Markakis, Michail
This paper presents the results of a computational study that compares simulated compartmental (differential equation) and Volterra models of the dynamic effects of insulin on blood glucose concentration in humans. In the ...
Guang-Hua Zhang; Wei-Zhou Jiang
2013-02-14T23:59:59.000Z
The liquid-gas phase transition in hot asymmetric nuclear matter is studied within density-dependent relativistic mean-field models where the density dependence is introduced according to the Brown-Rho scaling and constrained by available data at low densities and empirical properties of nuclear matter. The critical temperature of the liquid-gas phase transition is obtained to be 15.7 MeV in symmetric nuclear matter falling on the lower edge of the small experimental error bars. In hot asymmetric matter, the boundary of the phase-coexistence region is found to be sensitive to the density dependence of the symmetry energy. The critical pressure and the area of phase-coexistence region increases clearly with the softening of the symmetry energy. The critical temperature of hot asymmetric matter separating the gas phase from the LG coexistence phase is found to be higher for the softer symmetry energy.
Supplementary information Ionic currents underlying the dynamical model
Loewenstein, Yonatan
and the down states of the cell. A possible candidate for the slowly inactivating inward current is the h underlying the bidirectional transitions. Two types of persistent inward currents, persistent sodium and persistent calcium, have been characterized in Purkinje cells1,2 . Somatic Purkinje cell bistability has been
to cumulus transitions are therefore key to the subtropical energy balance, making it crucial for nu- merical, Warsaw, Poland. 5 Institute of Meteorology and Water Management-National Research Institute, Warsaw, Poland. 6 Foundation Science, Met Office, Exeter, UK. 7 Department of Regional Climate, Royal Netherlands
Comparing partial-wave amplitude parametrization with dynamical models of meson-nucleon scattering
Mark W. Paris; Ron L. Workman
2011-02-28T23:59:59.000Z
Relationships between partial-wave amplitude parametrizations, in particular the Chew-Mandelstam approach, and dynamical coupled-channel models are established and investigated. A bare pole corresponding to the Delta(1232) resonance, found in a recent dynamical-model fit to pion- and omega-meson production reactions, compares closely to one found in a unitary multichannel partial-wave amplitude parametrization of SAID. The model dependence of the bare pole precludes a direct connection between the approaches but is suggestive that the dynamical description and the phenomenological parametrization are closely related.
Tong, Fuhui
2009-05-15T23:59:59.000Z
This quantitative study derived from an on-going federal experimental research project targeting Spanish-speaking English language learners (ELLs) receiving services in four program models: control/experimental transitional bilingual education (TBE...
Isomorphic classical molecular dynamics model for an excess electronin a supercritical fluid
Miller III, Thomas F.
2008-08-04T23:59:59.000Z
Ring polymer molecular dynamics (RPMD) is used to directly simulate the dynamics of an excess electron in a supercritical fluid over a broad range of densities. The accuracy of the RPMD model is tested against numerically exact path integral statistics through the use of analytical continuation techniques. At low fluid densities, the RPMD model substantially underestimates the contribution of delocalized states to the dynamics of the excess electron. However, with increasing solvent density, the RPMD model improves, nearly satisfying analytical continuation constraints at densities approaching those of typical liquids. In the high density regime, quantum dispersion substantially decreases the self-diffusion of the solvated electron. In this regime where the dynamics of the electron is strongly coupled to the dynamics of the atoms in the fluid, trajectories that can reveal diffusive motion of the electron are long in comparison to {beta}{h_bar}.
Chi, K C; Reiner, David; Nuttall, William J
www.eprg.group.cam.ac.uk E P R G W O R K IN G P A P E R N O N -T E C H N IC A L S U M M A R Y DYNAMICS OF THE UK NATURAL GAS INDUSTRY: SYSTEM DYNAMICS MODELLING AND LONG-TERM ENERGY POLICY ANALYSIS EPRG Working Paper 0913... Cambridge Working Paper in Economics 0922 Kong Chyong Chi , David M. Reiner and William J. Nuttall The UK offshore natural gas and oil industry has a long and successful history and has been said to represent the pride of UK...
Dynamic reduced order modeling of entrained flow gasifiers
Monaghan, Rory F. D. (Rory Francis Desmond)
2010-01-01T23:59:59.000Z
Gasification-based energy systems coupled with carbon dioxide capture and storage technologies have the potential to reduce greenhouse gas emissions from continued use of abundant and secure fossil fuels. Dynamic reduced ...
Modeling Robot Dynamic Performance for Endpoint Force Control
Eppinger, Steven D.
1988-09-01T23:59:59.000Z
This research aims to understand the fundamental dynamic behavior of servo-controlled machinery in response to various types of sensory feedback. As an example of such a system, we study robot force control, a scheme ...
SIMULATING MARKET TRANSFORMATION DYNAMICS USING A HYBRID ENERGY ECONOMY MODEL
AT THE ADOPTION OF HYDROGEN FUEL CELL VEHICLES by Jimena Eyzaguirre M.Sc. Geology, University of Western Ontario, to develop policy-relevant information about dynamics in consumer preferences for hydrogen fuel cell vehicles
Multiscale Modeling of Process Dynamics and Microstructure Development...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of Process Dynamics and Microstructure Development in Laser-based Keyhole Welding and Additive Manufacturing Jun 05 2015 10:00 AM - 11:00 AM Wenda Tan, University of Utah, Salt...
Modeling the dynamics and depositional patterns of sandy rivers
Jerolmack, Douglas J
2006-01-01T23:59:59.000Z
This thesis seeks to advance our understanding of the dynamic nature, spatial organization and depositional record of topography in sand-bedded rivers. I examine patterns and processes over a wide range of scales, on Earth ...
Calibration of CDO Tranches with the Dynamical Generalized-Poisson Loss Model
Brigo, Damiano
Calibration of CDO Tranches with the Dynamical Generalized-Poisson Loss Model (updated shortened, and consistent calibration to quoted index CDO tranches and tranchelets for several maturities is feasible, as we dynamics, investigating calibration improve- ments and stability. JEL classification code: G13. AMS
Brownian Dynamics Model of Excited-State Relaxation in Solutions of Conjugated Oligomers
Yaron, David
1 Brownian Dynamics Model of Excited-State Relaxation in Solutions of Conjugated Oligomers Nicolae, Pittsburgh, Pennsylvania 15213. Excited state relaxation, conjugated polymers, Brownian dynamics. The effects, of the oligomer. A simple molecular mechanical form is used for the ground electronic state. The excitation energy