Vibronic coupling in icosahedral systems
Huang, R
2001-01-01
consideration. In this thesis, an explanation based on the competition between the two tunneling paths on the lowest APES is proposed. It is assumed that tunneling occurs along paths of steepest descent. The reversal in sign of the tunneling splitting, calculated using the WKB method, in the icosahedral H x h Jahn-Teller system is explained in terms of different tunneling paths along which the system moves as the strength of the vibronic coupling K sub h sub sub 1 changes. It is found that this sign reversal occurs when K sub h sub sub 1 /(h/2 pi)w approx 4.1. This result is very near to the original result of K sub h sub sub 1 /(h/2 pi)w approx 3.8 obtained using a totally different method. This reversal can be explained as follows; for weak vibronic coupling, the H symmetry state is dominated by tunneling along the steepest descent path of C sub 1 symmetry which connects two D sub 3 sub d wells via one point on the D sub 3 symmetry saddle trough; for strong coupling, the A symmetry state is dominated by tun...
Joubert-Doriol, Loïc; Ryabinkin, Ilya G; Izmaylov, Artur F
2013-12-21
In molecular systems containing conical intersections (CIs), a nontrivial geometric phase (GP) appears in the nuclear and electronic wave functions in the adiabatic representation. We study GP effects in nuclear dynamics of an N-dimensional linear vibronic coupling (LVC) model. The main impact of GP on low-energy nuclear dynamics is reduction of population transfer between the local minima of the LVC lower energy surface. For the LVC model, we proposed an isometric coordinate transformation that confines non-adiabatic effects within a two-dimensional subsystem interacting with an N - 2 dimensional environment. Since environmental modes do not couple electronic states, all GP effects originate from nuclear dynamics within the subsystem. We explored when the GP affects nuclear dynamics of the isolated subsystem, and how the subsystem-environment interaction can interfere with GP effects. Comparing quantum dynamics with and without GP allowed us to devise simple rules to determine significance of the GP for nuclear dynamics in this model.
Energy Technology Data Exchange (ETDEWEB)
Wykes, M., E-mail: mikewykes@gmail.com; Parambil, R.; Gierschner, J. [Madrid Institute for Advanced Studies, IMDEA Nanoscience, Calle Faraday 9, Campus Cantoblanco, 28049 Madrid (Spain); Beljonne, D. [Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons (Belgium)
2015-09-21
Here, we present a general approach to treating vibronic coupling in molecular crystals based on atomistic simulations of large clusters. Such clusters comprise model aggregates treated at the quantum chemical level embedded within a realistic environment treated at the molecular mechanics level. As we calculate ground and excited state equilibrium geometries and vibrational modes of model aggregates, our approach is able to capture effects arising from coupling to intermolecular degrees of freedom, absent from existing models relying on geometries and normal modes of single molecules. Using the geometries and vibrational modes of clusters, we are able to simulate the fluorescence spectra of aggregates for which the lowest excited state bears negligible oscillator strength (as is the case, e.g., ideal H-aggregates) by including both Franck-Condon (FC) and Herzberg-Teller (HT) vibronic transitions. The latter terms allow the adiabatic excited state of the cluster to couple with vibrations in a perturbative fashion via derivatives of the transition dipole moment along nuclear coordinates. While vibronic coupling simulations employing FC and HT terms are well established for single-molecules, to our knowledge this is the first time they are applied to molecular aggregates. Here, we apply this approach to the simulation of the low-temperature fluorescence spectrum of para-distyrylbenzene single-crystal H-aggregates and draw comparisons with coarse-grained Frenkel-Holstein approaches previously extensively applied to such systems.
Wykes, M.; Parambil, R.; Beljonne, D.; Gierschner, J.
2015-09-01
Here, we present a general approach to treating vibronic coupling in molecular crystals based on atomistic simulations of large clusters. Such clusters comprise model aggregates treated at the quantum chemical level embedded within a realistic environment treated at the molecular mechanics level. As we calculate ground and excited state equilibrium geometries and vibrational modes of model aggregates, our approach is able to capture effects arising from coupling to intermolecular degrees of freedom, absent from existing models relying on geometries and normal modes of single molecules. Using the geometries and vibrational modes of clusters, we are able to simulate the fluorescence spectra of aggregates for which the lowest excited state bears negligible oscillator strength (as is the case, e.g., ideal H-aggregates) by including both Franck-Condon (FC) and Herzberg-Teller (HT) vibronic transitions. The latter terms allow the adiabatic excited state of the cluster to couple with vibrations in a perturbative fashion via derivatives of the transition dipole moment along nuclear coordinates. While vibronic coupling simulations employing FC and HT terms are well established for single-molecules, to our knowledge this is the first time they are applied to molecular aggregates. Here, we apply this approach to the simulation of the low-temperature fluorescence spectrum of para-distyrylbenzene single-crystal H-aggregates and draw comparisons with coarse-grained Frenkel-Holstein approaches previously extensively applied to such systems.
Effects of Herzberg-Teller vibronic coupling on coherent excitation energy transfer
Zhang, Hou-Dao; Qiao, Qin; Xu, Rui-Xue; Yan, YiJing
2016-11-01
In this work, we study the effects of non-Condon vibronic coupling on the quantum coherence of excitation energy transfer, via the exact dissipaton-equation-of-motion evaluations on excitonic model systems. Field-triggered excitation energy transfer dynamics and two dimensional coherent spectroscopy are simulated for both Condon and non-Condon vibronic couplings. Our results clearly demonstrate that the non-Condon vibronic coupling intensifies the dynamical electronic-vibrational energy transfer and enhances the total system-and-bath quantum coherence. Moreover, the hybrid bath dynamics for non-Condon effects enriches the theoretical calculation, and further sheds light on the interpretation of the experimental nonlinear spectroscopy.
Li, Jiaru; Joubert-Doriol, Loïc; Izmaylov, Artur F
2017-08-14
We investigate geometric phase (GP) effects in nonadiabatic transitions through a conical intersection (CI) in an N-dimensional linear vibronic coupling (ND-LVC) model. This model allows for the coordinate transformation encompassing all nonadiabatic effects within a two-dimensional (2D) subsystem, while the other N - 2 dimensions form a system of uncoupled harmonic oscillators identical for both electronic states and coupled bi-linearly with the subsystem coordinates. The 2D subsystem governs ultra-fast nonadiabatic dynamics through the CI and provides a convenient model for studying GP effects. Parameters of the original ND-LVC model define the Hamiltonian of the transformed 2D subsystem and thus influence GP effects directly. Our analysis reveals what values of ND-LVC parameters can introduce symmetry breaking in the 2D subsystem that diminishes GP effects.
Parallelization strategy for large-scale vibronic coupling calculations.
Rabidoux, Scott M; Eijkhout, Victor; Stanton, John F
2014-12-26
The vibronic coupling model of Köppel, Domcke, and Cederbaum is a powerful means to understand, predict, and analyze electronic spectra of molecules, especially those that exhibit phenomena that involve breakdown of the Born-Oppenheimer approximation. In this work, we describe a new parallel algorithm for carrying out such calculations. The algorithm is conceptually founded upon a "stencil" representation of the required computational steps, which motivates an efficient strategy for coarse-grained parallelization. The equations involved in the direct-CI type diagonalization of the model Hamiltonian are presented, the parallelization strategy is discussed in detail, and the method is illustrated by calculations involving direct-product basis sets with as many as 17 vibrational modes and 130 billion basis functions.
Graus, M; Grimm, M; Metzger, C; Dauth, M; Tusche, C; Kirschner, J; Kümmel, S; Schöll, A; Reinert, F
2016-04-08
Electron-phonon coupling is one of the most fundamental effects in condensed matter physics. We here demonstrate that photoelectron momentum mapping can reveal and visualize the coupling between specific vibrational modes and electronic excitations. When imaging molecular orbitals with high energy resolution, the intensity patterns of photoelectrons of the vibronic sidebands of molecular states show characteristic changes due to the distortion of the molecular frame in the vibronically excited state. By comparison to simulations, an assignment of specific vibronic modes is possible, thus providing unique information on the coupling between electronic and vibronic excitation.
Towards quantification of vibronic coupling in photosynthetic antenna complexes
Energy Technology Data Exchange (ETDEWEB)
Singh, V. P.; Westberg, M.; Wang, C.; Gellen, T.; Engel, G. S., E-mail: gsengel@uchicago.edu [Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Dahlberg, P. D. [Graduate Program in the Biophysical Sciences, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Gardiner, A. T.; Cogdell, R. J. [Department of Botany, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, Scotland (United Kingdom)
2015-06-07
Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency—by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime.
Towards quantification of vibronic coupling in photosynthetic antenna complexes.
Singh, V P; Westberg, M; Wang, C; Dahlberg, P D; Gellen, T; Gardiner, A T; Cogdell, R J; Engel, G S
2015-06-07
Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency--by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime.
Van Duzor, Matthew; Mbaiwa, Foster; Wei, Jie; Singh, Tulsi; Mabbs, Richard; Sanov, Andrei; Cavanagh, Steven J; Gibson, Stephen T; Lewis, Brenton R; Gascooke, Jason R
2010-11-07
We present a comprehensive photoelectron imaging study of the O(2)(X (3)Σ(g)(-),v(')=0-6)←O(2)(-)(X (2)Π(g),v(")=0) and O(2)(a (1)Δ(g),v(')=0-4)←O(2)(-)(X (2)Π(g),v(")=0) photodetachment bands at wavelengths between 900 and 455 nm, examining the effect of vibronic coupling on the photoelectron angular distribution (PAD). This work extends the v(')=1-4 data for detachment into the ground electronic state, presented in a recent communication [R. Mabbs, F. Mbaiwa, J. Wei, M. Van Duzor, S. T. Gibson, S. J. Cavanagh, and B. R. Lewis, Phys. Rev. A 82, 011401(R) (2010)]. Measured vibronic intensities are compared to Franck-Condon predictions and used as supporting evidence of vibronic coupling. The results are analyzed within the context of the one-electron, zero core contribution (ZCC) model [R. M. Stehman and S. B. Woo, Phys. Rev. A 23, 2866 (1981)]. For both bands, the photoelectron anisotropy parameter variation with electron kinetic energy, β(E), displays the characteristics of photodetachment from a d-like orbital, consistent with the π(g)(∗) 2p highest occupied molecular orbital of O(2)(-). However, differences exist between the β(E) trends for detachment into different vibrational levels of the X (3)Σ(g)(-) and a (1)Δ(g) electronic states of O(2). The ZCC model invokes vibrational channel specific "detachment orbitals" and attributes this behavior to coupling of the electronic and nuclear motion in the parent anion. The spatial extent of the model detachment orbital is dependent on the final state of O(2): the higher the neutral vibrational excitation, the larger the electron binding energy. Although vibronic coupling is ignored in most theoretical treatments of PADs in the direct photodetachment of molecular anions, the present findings clearly show that it can be important. These results represent a benchmark data set for a relatively simple system, upon which to base rigorous tests of more sophisticated models.
Electronic and vibronic cluster models for the T24(G) level of d5 ions in tetrahedral symmetry
Parrot, R.; Boulanger, D.
2006-08-01
Electronic and vibronic cluster models are proposed to elaborate a general model for the T24(G) orbital triplet levels of d5 ions in tetrahedral symmetry. These models involve perturbation schemes and the diagonalization of the molecular electronic structure and vibronic Hamiltonian. First, the electronic fine structure is determined from the first- and second-order molecular spin-orbit (MSO) interaction. Then, Ham’s perturbation model for vibronic interactions is used in conjunction with the molecular model to analyze the vibronic interactions corresponding to a strong coupling to ɛ -vibrational modes. Then, a more general model is considered to account for the energy-level schemes and the strong intensity transfer observed, for example, on the fine structure lines of the T24(G) level of Mn2+ in ZnS and ZnSe. This model involves the diagonalization of the vibronic Hamiltonian for the T24(G) level and a perturbation model to account for vibronic interactions with all other multiplets of the d5 configuration. It is shown that the energy-level schemes as well as the strong intensity transfer of the fine structure lines of the T24(G) level of Mn2+ in ZnS and ZnSe are very well accounted for from the electronic molecular model involving the first- and second-order MSO interaction and from the proposed diagonalization and perturbation models for the coupling to ɛ -vibrational modes.
DEFF Research Database (Denmark)
Kuhlman, Thomas Scheby; Sauer, Stephan P.A.; Sølling, Theis I.
2012-01-01
In this paper, we discern two basic mechanisms of internal conversion processes; one direct, where immediate activation of coupling modes leads to fast population transfer and one indirect, where internal vibrational energy redistribution leads to equidistribution of energy, i.e., ergodicity......, and slower population transfer follows. Using model vibronic coupling Hamiltonians parameterized on the basis of coupled-cluster calculations, we investigate the nature of the Rydberg to valence excited-state internal conversion in two cycloketones, cyclobutanone and cyclopentanone. The two basic mechanisms...... can amply explain the significantly different time scales for this process in the two molecules, a difference which has also been reported in recent experimental findings [T. S. Kuhlman, T. I. Sølling, and K. B. Møller, ChemPhysChem. 13, 820 (2012)]...
Forces in EDO-TTF: Theoretical study of isotope and charge effects on vibronic coupling
Tokunaga, Ken
Isotope and charge effects on vibronic coupling constant (V) and energy gradient (g) of ethylenedioxy-tetrathiafulvalen (EDO-TTF) upon the electron injection into cation and electron removal from neutral molecule are investigated. It is found that normal modes which include C = C stretching motion generally have large V and g. For electron removal, three normal modes (v460, v470, and v480) have large Vi+ and gi+, and deuteration results in decrease of V46+ and increase of V47+. For electron injection, five normal modes (ν+42, ν+44, ν+45, ν+47, and ν+48) have large vi0 and gi0 deuteration results in increase of V045 and V048 and decrease of V047. From the analysis of vibronic coupling constants using vibronic coupling density (VCD), regional vibronic coupling constant (RVCC), and atomic vibronic coupling constant (AVCC), it is revealed that the change in normal mode vectors (d) due to the deuteration and electron removal (or injection) leads to the change in V.
Perlík, Václav; Cranston, Laura J; Cogdell, Richard J; Lincoln, Craig N; Savolainen, Janne; Šanda, František; Mančal, Tomáš; Hauer, Jürgen
2015-01-01
The initial energy transfer in photosynthesis occurs between the light-harvesting pigments and on ultrafast timescales. We analyze the carotenoid to bacteriochlorophyll energy transfer in LH2 Marichromatium purpuratum as well as in an artificial light-harvesting dyad system by using transient grating and two-dimensional electronic spectroscopy with 10 fs time resolution. We find that F\\"orster-type models reproduce the experimentally observed 60 fs transfer times, but overestimate coupling constants, which leads to a disagreement with both linear absorption and electronic 2D-spectra. We show that a vibronic model, which treats carotenoid vibrations on both electronic ground and excited state as part of the system's Hamiltonian, reproduces all measured quantities. Importantly, the vibronic model presented here can explain the fast energy transfer rates with only moderate coupling constants, which are in agreement with structure based calculations. Counterintuitively, the vibrational levels on the carotenoid el...
Perlík, Václav; Seibt, Joachim; Cranston, Laura J.; Cogdell, Richard J.; Lincoln, Craig N.; Savolainen, Janne; Šanda, František; Mančal, Tomáš; Hauer, Jürgen
2015-06-01
The initial energy transfer steps in photosynthesis occur on ultrafast timescales. We analyze the carotenoid to bacteriochlorophyll energy transfer in LH2 Marichromatium purpuratum as well as in an artificial light-harvesting dyad system by using transient grating and two-dimensional electronic spectroscopy with 10 fs time resolution. We find that Förster-type models reproduce the experimentally observed 60 fs transfer times, but overestimate coupling constants, which lead to a disagreement with both linear absorption and electronic 2D-spectra. We show that a vibronic model, which treats carotenoid vibrations on both electronic ground and excited states as part of the system's Hamiltonian, reproduces all measured quantities. Importantly, the vibronic model presented here can explain the fast energy transfer rates with only moderate coupling constants, which are in agreement with structure based calculations. Counterintuitively, the vibrational levels on the carotenoid electronic ground state play the central role in the excited state population transfer to bacteriochlorophyll; resonance between the donor-acceptor energy gap and the vibrational ground state energies is the physical basis of the ultrafast energy transfer rates in these systems.
Energy Technology Data Exchange (ETDEWEB)
Perlík, Václav; Seibt, Joachim; Šanda, František; Mančal, Tomáš [Institute of Physics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, Prague 121 16 (Czech Republic); Cranston, Laura J.; Cogdell, Richard J. [Institute of Molecular Cell and System Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow Biomedical Research Centre, 120 University Place, Glasgow G12 8TA, Scotland (United Kingdom); Lincoln, Craig N.; Hauer, Jürgen, E-mail: juergen.hauer@tuwien.ac.at [Photonics Institute, Vienna University of Technology, Gusshausstrasse 27, 1040 Vienna (Austria); Savolainen, Janne [Department of Physical Chemistry II, Ruhr-University Bochum, 44780 Bochum (Germany)
2015-06-07
The initial energy transfer steps in photosynthesis occur on ultrafast timescales. We analyze the carotenoid to bacteriochlorophyll energy transfer in LH2 Marichromatium purpuratum as well as in an artificial light-harvesting dyad system by using transient grating and two-dimensional electronic spectroscopy with 10 fs time resolution. We find that Förster-type models reproduce the experimentally observed 60 fs transfer times, but overestimate coupling constants, which lead to a disagreement with both linear absorption and electronic 2D-spectra. We show that a vibronic model, which treats carotenoid vibrations on both electronic ground and excited states as part of the system’s Hamiltonian, reproduces all measured quantities. Importantly, the vibronic model presented here can explain the fast energy transfer rates with only moderate coupling constants, which are in agreement with structure based calculations. Counterintuitively, the vibrational levels on the carotenoid electronic ground state play the central role in the excited state population transfer to bacteriochlorophyll; resonance between the donor-acceptor energy gap and the vibrational ground state energies is the physical basis of the ultrafast energy transfer rates in these systems.
Energy Technology Data Exchange (ETDEWEB)
Spano, F. C. [Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)
2015-05-14
The properties of polaritons in J-aggregate microcavities are explored using a Hamiltonian which treats exciton-vibrational coupling and exciton-photon coupling on equal footing. When the cavity mode is resonant with the lowest-energy (0-0) transition in the J-aggregate, two polaritons are formed, the lowest-energy polariton (LP) and its higher-energy partner (P{sub 1}), separated by the Rabi splitting. Strong coupling between the material and cavity modes leads to a decoupling of the exciton and vibrational degrees of freedom and an overall reduction of disorder within the LP. Such effects lead to an expanded material coherence length in the LP which leads to enhanced radiative decay rates. Additional spectral signatures include an amplification of the 0-0 peak coincident with a reduction in the 0-1 peak in the photoluminescence spectrum. It is also shown that the same cavity photon responsible for the LP/P{sub 1} splitting causes comparable splittings in the higher vibronic bands due to additional resonances between vibrationally excited states in the electronic ground state manifold and higher energy vibronic excitons.
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Albert, Julian; Falge, Mirjam; Hildenbrand, Heiko; Engel, Volker [Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Emil-Fischer-Str. 42, Campus Nord, Am Hubland, 97074 Würzburg (Germany); Gomez, Sandra; Sola, Ignacio R. [Departamento de Quimica Fisica, Universidad Complutense, 28040 Madrid (Spain)
2015-07-28
We theoretically investigate the photon-echo spectroscopy of coupled electron-nuclear quantum dynamics. Two situations are treated. In the first case, the Born-Oppenheimer (adiabatic) approximation holds. It is then possible to interpret the two-dimensional (2D) spectra in terms of vibrational motion taking place in different electronic states. In particular, pure vibrational coherences which are related to oscillations in the time-dependent third-order polarization can be identified. This concept fails in the second case, where strong non-adiabatic coupling leads to the breakdown of the Born-Oppenheimer-approximation. Then, the 2D-spectra reveal a complicated vibronic structure and vibrational coherences cannot be disentangled from the electronic motion.
Ye, Hong-zhou; Jiang, Hong
2014-01-01
Materials with spin-crossover (SCO) properties hold great potentials in information storage and therefore have received a lot of concerns in the recent decades. The hysteresis phenomena accompanying SCO is attributed to the intermolecular cooperativity whose underlying mechanism may have a vibronic origin. In this work, a new vibronic Ising-like model in which the elastic coupling between SCO centers is included by considering harmonic stretching and bending (SAB) interactions is proposed and solved by Monte Carlo simulations. The key parameters in the new model, $k_1$ and $k_2$, corresponding to the elastic constant of the stretching and bending mode, respectively, can be directly related to the macroscopic bulk and shear modulus of the material in study, which can be readily estimated either based on experimental measurements or first-principles calculations. The convergence issue in the MC simulations of the thermal hysteresis has been carefully checked, and it was found that the stable hysteresis loop can...
Flanagan, Moira L; Long, Phillip D; Dahlberg, Peter D; Rolczynski, Brian S; Massey, Sara C; Engel, Gregory S
2016-03-10
The bacterial reaction center is capable of both efficiently collecting and quickly transferring energy within the complex; therefore, the reaction center serves as a convenient model for both energy transfer and charge separation. To spectroscopically probe the interactions between the electronic excited states on the chromophores and their intricate relationship with vibrational motions in their environment, we examine coherences between the excited states. Here, we investigate this question by introducing a series of point mutations within 12 Å of the special pair of bacteriochlorophylls in the Rhodobacter sphaeroides reaction center. Using two-dimensional spectroscopy, we find that the time scales of energy transfer dynamics remain unperturbed by these mutations. However, within these spectra, we detect changes in the mixed vibrational-electronic coherences in these reaction centers. Our results indicate that resonance between bacteriochlorophyll vibrational modes and excitonic energy gaps promote electronic coherences and support current vibronic models of photosynthetic energy transfer.
Vibronic Coupling in the Ground State of Vinylidene ˜{X} ^1A_1 H_2CC
Gibson, Stephen T.; Laws, Benjamin A.; Guo, Hua; Neumark, Daniel; Lineberger, Carl; Field, Robert W.
2017-06-01
The nature of the isomeration process that turns vinylidene H_2CC to acetylene HCCH, requiring a 1,2-hydrogen atom shift across the molecule, is a long standing puzzle that has its origin in a 1989 photoelectron measurement of vinylidide (H_2CC^-). In recent years the photoelectron spectrum of vinylidide has been revisited, using improved experimental techniques, including velocity-map imaging for the detection of photoelectrons, low-temperature near-threshold methods (cryo-SEVI), and sophisticated ab inito calculations. The simple normal-mode structure, 1064 nm velocity-map image illustrated, is proving a challenge to decipher. However, the dramatic change in the photoelectron angular distribution of the inner-ring structure is characteristic of vibronic coupling. The lowest electronic state with the correct symmetry, ˜{B} ^{1}B_2, is 4eV higher in energy. K. M. Ervin et al. J. Chem. Phys. 91 5974 (1991) J. A. De Vine et al. J. Am. Chem. Soc. 138 16417 (2016) L. Guo et al. J. Phys. Chem. 119 8488 (2015) A. Weaver et al. J. Chem. Phys. 94 1740 (1991) Research supported by the Australian Research Council Discovery Project Grant DP160102585.
The effects of vibronic coupling on the photophysics of pi-conjugated oligomers and polymers
Yamagata, Hajime
A theoretical model describing photophysics of pi-conjugated aggregates, such as molecular crystals and polymer thin films, is developed. A Holstein-like Hamiltonian expressed with a multi-particle basis set is used to evaluate absorption and photoluminescence (PL) spectra. An analysis with line strength ratio proves to be a powerful diagnostic tool to obtain additional spectral signatures with which to distinguish H- vs. J-aggregation. For the H-aggregates absorption peak ratio, A 0-0/A 0-1, diminishes as the excitonic coupling increases. Also the PL peak ratio, I 0-0/I 0-1, is zero at T=0K with no disorder and the value increases as temperature and disorder increase. By contrast the J-aggregates show the opposite trends. Furthermore we will show the PL peak ratio provides a direct measurement of the exciton coherence length for a linear J-aggregate and could be expressed as I0-0/I 0-1 = Ncoh/gamma2. We will also show that it is inversely proportional to square root of temperature (T-1/2). Applying our theory to the herringbone style oligoacene molecular crystals, we show the lowest singlet exciton states are highly influenced by charge transfer (CT) states and the well known energetic gap in two polarized absorption spectra, so called Davydov Splitting (DS), is a product of the interaction. We have successfully reproduced the DS for all three oligoacenes without any free parameters. Inspired by the CT contribution in oligoacene crystals, we further develop Wannier-Mott exciton model and apply to disorder-free polydiacetylene (PDA) quantum wires, which have been shown to be extremely emissive. We will show the quantum wire is a J-aggregate and we once again derive the peak ratio and the coherence size relation, I0-0/I 0-1 = kappaNcoh/gamma 2, where kappa is a prefactor close to unity. Typical photophysical properties of polymer pi-stacks such as those occurring in P3HT films are well explained by the simple linear H-aggregate model. However several groups have
Vibronic coupling in Frenkel and charge-transfer states of oligothiophene crystals
Stradomska, Anna; Kulig, Waldemar; Petelenz, Piotr
A novel approach, recently proposed to describe exciton phonon coupling in Frenkel states of an infinite molecular crystal, is generalized to incorporate charge-transfer (CT) excitons. Both types of electronic excitations are treated on the same footing. The corresponding Hamiltonian in the Lang
Koppel, Horst
2013-06-01
We investigate the excitation of vibrational modes and its impact on the excitonic energy splittings in doubly hydrogen-bonded molecular dimers. The experimental analysis, performed in collaboration by S. Leutwyler and coworkers (Univ. Bern), is based on high-resolution resonant two-photon ionization spectroscopy. The potential energy surfaces underlying the theoretical investigation are obtained at the RICC2/aug-cc-pVTZ level and are used for the dynamical analysis in the framework of a well-established vibronic coupling approach. The vertical electronic Davydov splitting of the S_1 and S_2 excited states exceeds the observed excitonic splitting by a factor of 10--40. This discrepancy can be understood by considering the quenching of the excitonic splitting by the excitation of vibrational modes in the electronic transition. Two different approaches have been employed and found to reconcile theory and experiment. The analysis of the vibronic structure of the S_2 ← S_0 excitation spectrum focusses on the ortho-cyanophenol dimer as a representative example. Most of the observed spectral features can be reproduced by the calculations, although some deviations remain. In the second part, new results on the UV absorption spectrum of SO_2 will be presented. This is complementary to the excitonic systems in that higher vibrational energies are involved and a conical intersection is accessible to the nuclear motion. Using the concept of regularized diabatic states in combination with high-accuracy MRCI potential energy surfaces, semi-quantitative agreement with the complex experimental (low-resolution) spectrum has been achieved for the first time. P. Ottiger, S. Leutwyler and H. Köppel, J. Chem. Phys. 136, 174308 (2012). S. Kopec, P. Ottiger, S. Leutwyler and H. Köppel, J. Chem. Phys. 137, 184312 (2012). H. Köppel and B. Schubert, Mol. Phys. 104, 1069 (2006). C. Leveque, A. Komainda, R. Taieb and H. Köppel, J. Chem. Phys. 138, 044320 (2013).
Energy Technology Data Exchange (ETDEWEB)
Masuda, Suomi [Graduate School for Advanced Studies, Institute for Molecular Science, Okazaki 444-8585 (Japan); Gejo, Tatsuo [University of Hyogo, Kamigori-cho 678-1297 (Japan); Hiyama, Miyabi [Graduate School for Advanced Studies, Institute for Molecular Science, Okazaki 444-8585 (Japan); Kosugi, Nobuhiro [Graduate School for Advanced Studies, Institute for Molecular Science, Okazaki 444-8585 (Japan)]. E-mail: kosugi@ims.ac.jp
2005-06-15
High resolution angle-resolved ion-yield spectra are reported for the C1s->Rydberg excitations of acetylene. Vibronic coupling features are found in the energy regions of 3s{sigma}{sub g}/3{sigma}{sub u}*, 3p{sigma}{sub u}, and near threshold. By increasing retarding potentials for ion detectors to select more energetic fragmentation channels, the feature observed in the 90{sup o} direction is assigned to the C1s->3{sigma}{sub u}* valence state coupled with the C1s->1{pi}{sub g}* excited state via cis bending ({pi}{sub u}) vibrational mode.
Energy Technology Data Exchange (ETDEWEB)
Plenio, M. B.; Almeida, J.; Huelga, S. F. [Institute for Theoretical Physics, Albert-Einstein-Allee 11, University Ulm, D-89069 Ulm (Germany)
2013-12-21
We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in nonlinear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the nonlinear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of oscillatory behaviour using 2D photon echo techniques to corroborate the fundamental importance of the interplay of electronic and vibrational degrees of freedom in the dynamics of light harvesting aggregates.
Plenio, M B; Almeida, J; Huelga, S F
2013-12-21
We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in nonlinear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the nonlinear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of oscillatory behaviour using 2D photon echo techniques to corroborate the fundamental importance of the interplay of electronic and vibrational degrees of freedom in the dynamics of light harvesting aggregates.
Vibronic eigenstates and the geometric phase effect in the (2)E″ state of NO3.
Eisfeld, Wolfgang; Viel, Alexandra
2017-01-21
The (2)E″ state of NO3, a prototype for the Jahn-Teller effect, has been an enigma and a challenge for a long time for both experiment and theory. We present a detailed theoretical study of the vibronic quantum dynamics in this electronic state, uncovering the effects of tunnelling, geometric phase, and symmetry. To this end, 45 vibronic levels of NO3 in the (2)E″ state are determined accurately and analyzed thoroughly. The computation is based on a high quality diabatic potential representation of the two-sheeted surface of the (2)E″ state developed by us [W. Eisfeld et al., J. Chem. Phys. 140, 224109 (2014)] and on the multi-configuration time dependent Hartree approach. The vibrational eigenstates of the NO3(-) anion are determined and analyzed as well to gain a deeper understanding of the symmetry properties of such D3h symmetric systems. To this end, 61 eigenstates of the NO3(-) anion ground state are computed using the single sheeted potential surface of the (1)A1 state published in the same reference quoted above. The assignments of both the vibrational and vibronic levels are discussed. A simple model is proposed to rationalize the computed NO3 spectrum strongly influenced by the Jahn-Teller couplings, the associated geometric phase effect, and the tunnelling. Comparison with the available spectroscopic data is also presented.
Energy Technology Data Exchange (ETDEWEB)
Tsukerblat, Boris, E-mail: tsuker@bgu.ac.il, E-mail: andrew.palii@uv.es [Ben-Gurion University of the Negev, Beer-Sheva (Israel); Palii, Andrew, E-mail: tsuker@bgu.ac.il, E-mail: andrew.palii@uv.es [Institute of Applied Physics, Academy of Sciences of Moldova, Kishinev (Moldova, Republic of); Clemente-Juan, Juan Modesto; Coronado, Eugenio [Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna (Spain)
2015-10-07
Our interest in this article is prompted by the vibronic problem of charge polarized states in the four-dot molecular quantum cellular automata (mQCA), a paradigm for nanoelectronics, in which binary information is encoded in charge configuration of the mQCA cell. Here, we report the evaluation of the electronic levels and adiabatic potentials of mixed-valence (MV) tetra-ruthenium (2Ru(II) + 2Ru(III)) derivatives (assembled as two coupled Creutz-Taube complexes) for which molecular implementations of quantum cellular automata (QCA) was proposed. The cell based on this molecule includes two holes shared among four spinless sites and correspondingly we employ the model which takes into account the two relevant electron transfer processes (through the side and through the diagonal of the square) as well as the difference in Coulomb energies for different instant positions of localization of the hole pair. The combined Jahn-Teller (JT) and pseudo JT vibronic coupling is treated within the conventional Piepho-Krauzs-Schatz model adapted to a bi-electronic MV species with the square-planar topology. The adiabatic potentials are evaluated for the low lying Coulomb levels in which the antipodal sites are occupied, the case just actual for utilization in mQCA. The conditions for the vibronic self-trapping in spin-singlet and spin-triplet states are revealed in terms of the two actual transfer pathways parameters and the strength of the vibronic coupling. Spin related effects in degrees of the localization which are found for spin-singlet and spin-triplet states are discussed. The polarization of the cell is evaluated and we demonstrate how the partial delocalization caused by the joint action of the vibronic coupling and electron transfer processes influences polarization of a four-dot cell. The results obtained within the adiabatic approach are compared with those based on the numerical solution of the dynamic vibronic problem. Finally, the Coulomb interaction between
Tsukerblat, Boris; Palii, Andrew; Clemente-Juan, Juan Modesto; Coronado, Eugenio
2015-10-07
Our interest in this article is prompted by the vibronic problem of charge polarized states in the four-dot molecular quantum cellular automata (mQCA), a paradigm for nanoelectronics, in which binary information is encoded in charge configuration of the mQCA cell. Here, we report the evaluation of the electronic levels and adiabatic potentials of mixed-valence (MV) tetra-ruthenium (2Ru(ii) + 2Ru(iii)) derivatives (assembled as two coupled Creutz-Taube complexes) for which molecular implementations of quantum cellular automata (QCA) was proposed. The cell based on this molecule includes two holes shared among four spinless sites and correspondingly we employ the model which takes into account the two relevant electron transfer processes (through the side and through the diagonal of the square) as well as the difference in Coulomb energies for different instant positions of localization of the hole pair. The combined Jahn-Teller (JT) and pseudo JT vibronic coupling is treated within the conventional Piepho-Krauzs-Schatz model adapted to a bi-electronic MV species with the square-planar topology. The adiabatic potentials are evaluated for the low lying Coulomb levels in which the antipodal sites are occupied, the case just actual for utilization in mQCA. The conditions for the vibronic self-trapping in spin-singlet and spin-triplet states are revealed in terms of the two actual transfer pathways parameters and the strength of the vibronic coupling. Spin related effects in degrees of the localization which are found for spin-singlet and spin-triplet states are discussed. The polarization of the cell is evaluated and we demonstrate how the partial delocalization caused by the joint action of the vibronic coupling and electron transfer processes influences polarization of a four-dot cell. The results obtained within the adiabatic approach are compared with those based on the numerical solution of the dynamic vibronic problem. Finally, the Coulomb interaction between
Reassigning the CaH+ 11Σ → 21Σ vibronic transition with CaD+
Condoluci, J.; Janardan, S.; Calvin, A. T.; Rugango, R.; Shu, G.; Sherrill, C. D.; Brown, K. R.
2017-12-01
We observe vibronic transitions in CaD+ between the 11Σ and 21Σ electronic states by resonance enhanced multiphoton photodissociation spectroscopy in a Coulomb crystal. The vibronic transitions are compared with previous measurements on CaH+. The result is a revised assignment of the CaH+ vibronic levels and a disagreement with multi-state-complete-active-space second-order perturbation theory theoretical calculations by approximately 700 cm-1. Updated high-level coupled-cluster calculations that include core-valence correlations reduce the disagreement between theory and experiment to 300 cm-1.
Rabi-vibronic resonance with large number of vibrational quanta
Glenn, R.; Raikh, M. E.
2011-01-01
We study theoretically the Rabi oscillations of a resonantly driven two-level system linearly coupled to a harmonic oscillator (vibrational mode) with frequency, \\omega_0. We show that for weak coupling, \\omega_p \\ll \\omega_0, where \\omega_p is the polaronic shift, Rabi oscillations are strongly modified in the vicinity of the Rabi-vibronic resonance \\Omega_R = \\omega_0, where \\Omega_R is the Rabi frequency. The width of the resonance is (\\Omega_R-\\omega_0) \\sim \\omega_p^{2/3} \\omega_0^{1/3} ...
The nature of the low energy band of the Fenna-Matthews-Olson complex: vibronic signatures.
Caycedo-Soler, Felipe; Chin, Alex W; Almeida, Javier; Huelga, Susana F; Plenio, Martin B
2012-04-21
Based entirely upon actual experimental observations on electron-phonon coupling, we develop a theoretical framework to show that the lowest energy band of the Fenna-Matthews-Olson complex exhibits observable features due to the quantum nature of the vibrational manifolds present in its chromophores. The study of linear spectra provides us with the basis to understand the dynamical features arising from the vibronic structure in nonlinear spectra in a progressive fashion, starting from a microscopic model to finally performing an inhomogeneous average. We show that the discreteness of the vibronic structure can be witnessed by probing the diagonal peaks of the nonlinear spectra by means of a relative phase shift in the waiting time resolved signal. Moreover, we demonstrate that the photon-echo and non-rephasing paths are sensitive to different harmonics in the vibrational manifold when static disorder is taken into account. Supported by analytical and numerical calculations, we show that non-diagonal resonances in the 2D spectra in the waiting time, further capture the discreteness of vibrations through a modulation of the amplitude without any effect in the signal intrinsic frequency. This fact generates a signal that is highly sensitive to correlations in the static disorder of the excitonic energy albeit protected against dephasing due to inhomogeneities of the vibrational ensemble.
COUPLED CHEMOTAXIS FLUID MODEL
LORZ, ALEXANDER
2010-06-01
We consider a model system for the collective behavior of oxygen-driven swimming bacteria in an aquatic fluid. In certain parameter regimes, such suspensions of bacteria feature large-scale convection patterns as a result of the hydrodynamic interaction between bacteria. The presented model consist of a parabolicparabolic chemotaxis system for the oxygen concentration and the bacteria density coupled to an incompressible Stokes equation for the fluid driven by a gravitational force of the heavier bacteria. We show local existence of weak solutions in a bounded domain in d, d = 2, 3 with no-flux boundary condition and in 2 in the case of inhomogeneous Dirichlet conditions for the oxygen. © 2010 World Scientific Publishing Company.
Patchkovskii, Serguei; Schuurman, Michael S.
2017-11-01
We present derivation and implementation of the multiconfigurational strong-field approximation with Gaussian nuclear wave packets (MC-SFA-GWP)—a version of the molecular strong-field approximation which treats all electronic and nuclear degrees of freedom, including their correlations, quantum mechanically. The technique allows realistic simulation of high-order-harmonic emission in polyatomic molecules without invoking reduced-dimensionality models for the nuclear motion or the electronic structure. We use MC-SFA-GWP to model isotope effects in high-order-harmonic-generation (HHG) spectroscopy of methane. The HHG emission in this molecule transiently involves the strongly vibronically coupled F22 electronic state of the CH4+ cation. We show that the isotopic HHG ratio in methane contains signatures of (a) field-free vibronic dynamics at the conical intersection (CI); (b) resonant features in the recombination cross sections; (c) laser-driven bound-state dynamics; as well as (d) the well-known short-time Gaussian decay of the emission. We assign the intrinsic vibronic feature (a) to a relatively long-lived (≥4 fs) vibronic wave packet of the singly excited ν4 (t2) and ν2 (e ) vibrational modes, strongly coupled to the components of the F22 electronic state. We demonstrate that these physical effects differ in their dependence on the wavelength, intensity, and duration of the driving pulse, allowing them to be disentangled. We thus show that HHG spectroscopy provides a versatile tool for exploring both conical intersections and resonant features in photorecombination matrix elements in the regime not easily accessible with other techniques.
Vibrational and vibronic coherences in the dynamics of the FMO complex
Energy Technology Data Exchange (ETDEWEB)
Liu, Xiaomeng; Kühn, Oliver, E-mail: oliver.kuehn@uni-rostock.de
2016-12-20
The coupled exciton–vibrational dynamics of a seven site Frenkel exciton model of the Fenna–Matthews–Olson (FMO) complex is investigated using a Quantum Master Equation approach. Thereby, one vibrational mode per monomer is treated explicitly as being part of the relevant system. Emphasis is put on the comparison of this model with that of a purely excitonic relevant system. Further, the effects of two different approximations to the exciton–vibrational basis are investigated, namely the one- and two-particle description. Analysis of the vibronic and vibrational density matrix in the site basis points to the importance of on- and inter-site coherences for the exciton transfer. Here, one- and two-particle approximations give rise to qualitatively different results.
Xie, Yu; Jiang, Shengshi; Zheng, Jie; Lan, Zhenggang
2017-12-21
Photoinduced excited-state electron and energy transfer processes are crucial in biological photoharvesting systems and organic photovoltaic devices. We discuss the construction of a diabatic vibronic Hamiltonian for the proper treatment of these processes involving the projection approach acting on both electronic wave functions and vibrational modes. In the electronic part, the wave function projection approach is used to construct the diabatic Hamiltonian in which both local excited states and charge-transfer states are included on the same footing. For the vibrational degrees of freedom, the vibronic couplings in the diabatic Hamiltonian are obtained in the basis of the pseudonormal modes localized on each monomer site by applying delocalized-to-localized mode projection. This systematic approach allows us to construct the vibronic diabatic Hamiltonian in molecular aggregates.
Universality of coupled Potts models
Energy Technology Data Exchange (ETDEWEB)
Dotsenko, V.S.; Jacobsen, J.L. E-mail: jacobsen@ipno.in2p3.fr; Nguyen, X.S.; Santachiara, Raoul
2002-06-10
We study systems of M Potts models coupled by their local energy density. Each model is taken to have a distinct number of states, and the permutational symmetry S{sub M} present in the case of identical coupled models is thus broken initially. The duality transformations within the space of 2{sup M}-1 multi-energy couplings are shown to have a particularly simple form. The selfdual manifold has dimension D{sub M}=2{sup M-1}-1. Specialising to the case M=3, we identify a unique non-trivial critical point in the three-dimensional selfdual space. We compare its critical exponents as computed from the perturbative renormalisation group with numerical transfer matrix results. Our main objective is to provide evidence that at the critical point of three different coupled models the symmetry S{sub 3} is restored.
Prospects for coupled modelling
Energy Technology Data Exchange (ETDEWEB)
Savage, D.
2012-07-01
Clay-based buffer and tunnel backfill materials are important barriers in the KBS- 3 repository concept for final disposal of spent nuclear fuel in Finland. Significant changes can be expected to occur to the properties and behaviour of buffer and backfill, especially during re-saturation and through the thermal period. Reactions will occur in response to thermal and chemical gradients, induced by the thermal output of the spent fuel and at interfaces between different barrier materials, such as cement/clay, steel/clay etc. Processes of ion exchange, mineral dissolution and precipitation, and swelling can lead to significant re-distribution of mass and evolution of physical properties so that reliable predictive modelling of future behaviour and properties must be made. This report evaluates the current status of modelling of buffer and backfill evolution and tries to assess the potential future capabilities in the short- to medium-term (5-10 years) in a number of technical areas: (1) Non-isothermal (T-H-M-C-B) modelling and the potential for cementation, (2) The consistency of models, (3) Swelling pressure, (4) Cement-bentonite interactions, (5) Iron-bentonite interactions, (6) Mechanical (shear) behavior, and (7) Bentonite erosion.
Vibronic origin of long-lived coherence in an artificial molecular light harvester.
Lim, James; Paleček, David; Caycedo-Soler, Felipe; Lincoln, Craig N; Prior, Javier; von Berlepsch, Hans; Huelga, Susana F; Plenio, Martin B; Zigmantas, Donatas; Hauer, Jürgen
2015-07-09
Natural and artificial light-harvesting processes have recently gained new interest. Signatures of long-lasting coherence in spectroscopic signals of biological systems have been repeatedly observed, albeit their origin is a matter of ongoing debate, as it is unclear how the loss of coherence due to interaction with the noisy environments in such systems is averted. Here we report experimental and theoretical verification of coherent exciton-vibrational (vibronic) coupling as the origin of long-lasting coherence in an artificial light harvester, a molecular J-aggregate. In this macroscopically aligned tubular system, polarization-controlled 2D spectroscopy delivers an uncongested and specific optical response as an ideal foundation for an in-depth theoretical description. We derive analytical expressions that show under which general conditions vibronic coupling leads to prolonged excited-state coherence.
Exciton dynamics in perturbed vibronic molecular aggregates
Directory of Open Access Journals (Sweden)
C. Brüning
2016-07-01
Full Text Available A site specific perturbation of a photo-excited molecular aggregate can lead to a localization of excitonic energy. We investigate this localization dynamics for laser-prepared excited states. Changing the parameters of the electric field significantly influences the exciton localization which offers the possibility for a selective control of this process. This is demonstrated for aggregates possessing a single vibrational degree of freedom per monomer unit. It is shown that the effects identified for the molecular dimer can be generalized to larger aggregates with a high density of vibronic states.
Coupling constant in dispersive model
Indian Academy of Sciences (India)
Abstract. The average of the moments for event shapes in e+e− → hadrons within the con- text of next-to-leading order (NLO) perturbative QCD prediction in dispersive model is studied. Moments used in this article are 〈1 − T〉, 〈ρ〉, 〈BT〉 and 〈BW〉. We extract αs, the coupling con- stant in perturbative theory and α0 in the ...
The Challenges to Coupling Dynamic Geospatial Models
Energy Technology Data Exchange (ETDEWEB)
Goldstein, N
2006-06-23
Many applications of modeling spatial dynamic systems focus on a single system and a single process, ignoring the geographic and systemic context of the processes being modeled. A solution to this problem is the coupled modeling of spatial dynamic systems. Coupled modeling is challenging for both technical reasons, as well as conceptual reasons. This paper explores the benefits and challenges to coupling or linking spatial dynamic models, from loose coupling, where information transfer between models is done by hand, to tight coupling, where two (or more) models are merged as one. To illustrate the challenges, a coupled model of Urbanization and Wildfire Risk is presented. This model, called Vesta, was applied to the Santa Barbara, California region (using real geospatial data), where Urbanization and Wildfires occur and recur, respectively. The preliminary results of the model coupling illustrate that coupled modeling can lead to insight into the consequences of processes acting on their own.
Vibronic relaxation processes of the F{sub A} center in RbCl:Li
Energy Technology Data Exchange (ETDEWEB)
Akiyama, Norio, E-mail: akiyama@ee.ous.ac.jp [Department of Electrical and Electronic Engineering, Okayama University of Science, Okayama 700-0005 (Japan); Shirosaki, Tomoki [Department of Electrical and Electronic Engineering, Okayama University of Science, Okayama 700-0005 (Japan); Muramatsu, Shinji [Department of Electrical and Electronic Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan); Baldacchini, Giuseppe [Home, via G. Quattrucci 246, 00046 Grottaferrata, Rome (Italy)
2012-07-15
The vibronic relaxation process of F{sub A} centers in RbCl:Li, which have Type I emission at low temperatures and Type II emission at high temperatures, has been studied at 10 and 77 K by measuring the resonant secondary radiation (RSR) spectrum from optically excited F{sub A} centers with pico-second time-resolved spectroscopy. This study has been prompted by the quest to improve our knowledge on the de-excitation process in the F{sub A} centers. The adiabatic potential energy curves are deduced from a theoretical analysis of the measured RSR spectra and compared with those already known. It is shown that Type II relaxation observed at 77 K occurs after Type I relaxation, supporting in turn a model proposed by Baldacchini et al. based on photoluminescence measurements. - Highlights: Black-Right-Pointing-Pointer The vibronic relaxation process of F{sub A} centers in a laser active material. Black-Right-Pointing-Pointer The explanation of the vibronic relaxation process of F{sub A} centers with the coexistence of Type I and Type II relaxations. Black-Right-Pointing-Pointer Results of the time-resolved resonant secondary radiation (RSR) measurement. Black-Right-Pointing-Pointer A new model of the de-excitation process in the F{sub A} centers.
A multilingual programming model for coupled systems.
Energy Technology Data Exchange (ETDEWEB)
Ong, E. T.; Larson, J. W.; Norris, B.; Tobis, M.; Steder, M.; Jacob, R. L.; Mathematics and Computer Science; Univ. of Wisconsin; Univ. of Chicago; The Australian National Univ.
2008-01-01
Multiphysics and multiscale simulation systems share a common software requirement-infrastructure to implement data exchanges between their constituent parts-often called the coupling problem. On distributed-memory parallel platforms, the coupling problem is complicated by the need to describe, transfer, and transform distributed data, known as the parallel coupling problem. Parallel coupling is emerging as a new grand challenge in computational science as scientists attempt to build multiscale and multiphysics systems on parallel platforms. An additional coupling problem in these systems is language interoperability between their constituent codes. We have created a multilingual parallel coupling programming model based on a successful open-source parallel coupling library, the Model Coupling Toolkit (MCT). This programming model's capabilities reach beyond MCT's native Fortran implementation to include bindings for the C++ and Python programming languages. We describe the method used to generate the interlanguage bindings. This approach enables an object-based programming model for implementing parallel couplings in non-Fortran coupled systems and in systems with language heterogeneity. We describe the C++ and Python versions of the MCT programming model and provide short examples. We report preliminary performance results for the MCT interpolation benchmark. We describe a major Python application that uses the MCT Python bindings, a Python implementation of the control and coupling infrastructure for the community climate system model. We conclude with a discussion of the significance of this work to productivity computing in multidisciplinary computational science.
Huh, Joonsuk; Yung, Man-Hong
2017-08-07
Molecular vibroic spectroscopy, where the transitions involve non-trivial Bosonic correlation due to the Duschinsky Rotation, is strongly believed to be in a similar complexity class as Boson Sampling. At finite temperature, the problem is represented as a Boson Sampling experiment with correlated Gaussian input states. This molecular problem with temperature effect is intimately related to the various versions of Boson Sampling sharing the similar computational complexity. Here we provide a full description to this relation in the context of Gaussian Boson Sampling. We find a hierarchical structure, which illustrates the relationship among various Boson Sampling schemes. Specifically, we show that every instance of Gaussian Boson Sampling with an initial correlation can be simulated by an instance of Gaussian Boson Sampling without initial correlation, with only a polynomial overhead. Since every Gaussian state is associated with a thermal state, our result implies that every sampling problem in molecular vibronic transitions, at any temperature, can be simulated by Gaussian Boson Sampling associated with a product of vacuum modes. We refer such a generalized Gaussian Boson Sampling motivated by the molecular sampling problem as Vibronic Boson Sampling.
Vibronic effects in the spectroscopy and dynamics of C-phycocyanin
Womick, Jordan M.; West, Brantley A.; Scherer, Norbert F.; Moran, Andrew M.
2012-08-01
Femtosecond laser spectroscopies are used to investigate the influence of intramolecular nuclear modes on electronic relaxation in the cyanobacterial light harvesting protein, C-phycocyanin (CPC). Of particular interest are sub-ps dynamics localized on pairs of closely spaced phycocyanobilin pigments (i.e. dimers). Experiments conducted under different polarization conditions are used to distinguish isotropic and anisotropic vibrational modes within the dimers. Two isotropic nuclear modes are detected near 185 and 260 cm-1 using two-dimensional photon echo spectroscopy. In addition, a transient absorption anisotropy measurement reveals vibrational resonances associated with (out-of-plane) anisotropic nuclear modes near 640 and 815 cm-1. We investigate two possible origins for the recurrences in the anisotropy. A mechanism involving ground state nuclear coherences in the Condon approximation is ruled out by comparing the potential energy surfaces of the excitons to the direction of wavepacket motion. Electronic structure calculations suggest that non-Condon effects are the most likely explanation for the beats observed in the anisotropy. Such non-Condon effects also hold interesting implications for the vibronic exciton electronic structure of CPC. We calculate non-Condon intermolecular couplings in the dimer as large as 10 cm-1, which suggests that these effects are not negligible and deserve further consideration. Our findings provide additional insights into the sub-100 fs vibronic relaxation channel found in the closely related protein, allophycocyanin, whose pigment dimers possess nearly the same geometry and intermolecular Coulombic interactions as CPC. This study underscores the complex interplay of intramolecular vibronic coupling and site energy tuning in photosynthetic light harvesting.
Generalized coupling in the Kuramoto model
DEFF Research Database (Denmark)
Filatrella, G.; Pedersen, Niels Falsig; Wiesenfeld, K.
2007-01-01
We propose a modification of the Kuramoto model to account for the effective change in the coupling constant among the oscillators, as suggested by some experiments on Josephson junction, laser arrays, and mechanical systems, where the active elements are turned on one by one. The resulting model...... with the behavior of Josephson junctions coupled via a cavity....
Vibronic coupling in the excited-states of carotenoids
Energy Technology Data Exchange (ETDEWEB)
Miki, Takeshi [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg, Germany; Buckup, Tiago [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg, Germany; Krause, Marie S. [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg, Germany; Southall, June [College of Medical; Veterinary, and Life Science; University of Glasgow; G12 8QQ Glasgow, UK; Cogdell, Richard J. [College of Medical; Veterinary, and Life Science; University of Glasgow; G12 8QQ Glasgow, UK; Motzkus, Marcus [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg, Germany
2016-01-01
The ultrafast femtochemistry of carotenoids is governed by the interaction between electronic excited states, which has been explained by the relaxation dynamics within a few hundred femtoseconds from the lowest optically allowed excited state S_{2}to the optically dark state S_{1}.
Overview of the Coupled Model Intercomparison Project.
Meehl, Gerald A.; Covey, Curt; McAvaney, Bryant; Latif, Mojib; Stouffer, Ronald J.
2005-01-01
The Coupled Model Intercomparison Project (CMIP) involves study and intercomparison of multi-model simulations of present and future climate. The simulations of the future use idealized forcing in increase is compounded which CO2 1% yr-1 until it doubles (near year 70) with global coupled models that contain, typically, components representing atmosphere, ocean, sea ice, and land surface. Results from CMIP diagnostic subprojects were presented at the Second CMIP Workshop held at the Max Planck Institute for Meteorology in Hamburg, Germany, in September 2003. Significant progress in diagnosing and understanding results from global coupled models has been made since the time of the First CMIP Workshop in Melbourne, Australia, in 1998. For example, the issue of flux adjustment is slowly fading as more and more models obtain stable multi-century surface climates without them. El Niño variability, usually about half the observed amplitude in the previous generation of coupled models, is now more accurately simulated in the present generation of global coupled models, though there are still biases in simulating the patterns of maximum variability. Typical resolutions of atmospheric component models contained in coupled models are now usually around 2.5° latitude-longitude, with the ocean components often having about twice the atmospheric model resolution, with even higher resolution in the equatorial Tropics. Some new-generation coupled models have atmospheric resolutions of around 1.5° latitude-longitude. Modeling groups now routinely run the CMIP control and 1% CO2 simulations in addition to twentieth- and twenty-first-century climate simulations with a variety of forcings e.g., volcanoes, solar variability, anthropogenic sulfate aerosols, ozone, and greenhouse gases, with the anthropogenic forcings for future climate as well. However, persistent systematic errors noted in previous generations of global coupled models are still present in the current generation (e
Coupled finite element modeling of piezothermoelastic materials
Senousy, M. S.; Rajapakse, R. K. N. D.; Gadala, M.
2007-04-01
The governing equations of piezo-thermoelastic materials show full coupling between mechanical, electric, and temperature fields. It is often assumed in the literature that in high-frequency oscillations, the coupling between the temperature and mechanical displacement and electric field is small and, therefore, can be neglected. A solution for the temperature field is then determined from an uncoupled equation. A finite element (FE) model that accounts for full coupling between the mechanical, electric, and thermal fields, nonlinear constitutive behavior and heat generation resulting from dielectric losses under alternating driving fields is under development. This paper presents a linear fully coupled model as an early development of the fully coupled nonlinear FE model. In the linear model, a solution for all field variables is obtained simultaneously and compared with the uncoupled solution. The finite element model is based on the weighted-residual principle and uses 2-D four-node isoparametric finite elements with four degrees of freedom per node. A thin piezoelectric square disk is modeled to obtain some preliminary understanding of the coupled fields in a piezoelectric stack actuator.
Coupling constant in dispersive model
Indian Academy of Sciences (India)
perturbative theory using the dispersive model. By fitting the experimental data, the values of ( M Z ° ) = 0.1171 ± 0.00229 and 0 ( I = 2 GeV ) = 0.5068 ± 0.0440 are found. Our results are consistent with the above model. Our results are also ...
Ab initio ro-vibronic spectroscopy of SiCCl (X{sup ~2}Π)
Energy Technology Data Exchange (ETDEWEB)
Brites, Vincent [Université d’Evry Val d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, LAMBE CNRS UMR 8587, Boulevard F. Mitterrand, 91025 Evry Cedex (France); Mitrushchenkov, Alexander O.; Léonard, Céline, E-mail: celine.leonard@u-pem.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Peterson, Kirk A. [Department of Chemistry, Washington State University, Pullman, Washington 99164 (United States)
2014-07-21
The full dimensional potential energy surfaces of the {sup 2}A{sup ′} and {sup 2}A{sup ′′} electronic components of X{sup ~2}Π SiCCl have been computed using the explicitly correlated coupled cluster method, UCCSD(T)-F12b, combined with a composite approach taking into account basis set incompleteness, core-valence correlation, scalar relativity, and higher order excitations. The spin-orbit and dipole moment surfaces have also been computed ab initio. The ro-vibronic energy levels and absorption spectrum at 5 K have been determined from variational calculations. The influence of each correction on the fundamental frequencies is discussed. An assignment is proposed for bands observed in the LIF experiment of Smith et al. [J. Chem. Phys. 117, 6446 (2002)]. The overall agreement between the experimental and calculated ro-vibronic levels is better than 7 cm{sup −1} which is comparable with the 10–20 cm{sup −1} resolution of the emission spectrum.
Coupled wake boundary layer model of windfarms
Stevens, Richard; Gayme, Dennice; Meneveau, Charles
2014-11-01
We present a coupled wake boundary layer (CWBL) model that describes the distribution of the power output in a windfarm. The model couples the traditional, industry-standard wake expansion/superposition approach with a top-down model for the overall windfarm boundary layer structure. Wake models capture the effect of turbine positioning, while the top-down approach represents the interaction between the windturbine wakes and the atmospheric boundary layer. Each portion of the CWBL model requires specification of a parameter that is unknown a-priori. The wake model requires the wake expansion rate, whereas the top-down model requires the effective spanwise turbine spacing within which the model's momentum balance is relevant. The wake expansion rate is obtained by matching the mean velocity at the turbine from both approaches, while the effective spanwise turbine spacing is determined from the wake model. Coupling of the constitutive components of the CWBL model is achieved by iterating these parameters until convergence is reached. We show that the CWBL model predictions compare more favorably with large eddy simulation results than those made with either the wake or top-down model in isolation and that the model can be applied successfully to the Horns Rev and Nysted windfarms. The `Fellowships for Young Energy Scientists' (YES!) of the Foundation for Fundamental Research on Matter supported by NWO, and NSF Grant #1243482.
An Appraisal of Coupled Climate Model Simulations
Energy Technology Data Exchange (ETDEWEB)
Sperber, K; Gleckler, P; Covey, C; Taylor, K; Bader, D; Phillips, T; Fiorino, M; Achutarao, K
2004-02-24
In 2002, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) proposed the concept for a state-of-the-science appraisal of climate models to be performed approximately every two years. Motivation for this idea arose from the perceived needs of the international modeling groups and the broader climate research community to document progress more frequently than provided by the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports. A committee of external reviewers, which included senior researchers from four leading international modeling centers, supported the concept by stating in its review: ''The panel enthusiastically endorses the suggestion that PCMDI develop an independent appraisal of coupled model performance every 2-3 years. This would provide a useful 'mid-course' evaluation of modeling progress in the context of larger IPCC and national assessment activities, and should include both coupled and single-component model evaluations.''
Fractional dynamical model for neurovascular coupling
Belkhatir, Zehor
2014-08-01
The neurovascular coupling is a key mechanism linking the neural activity to the hemodynamic behavior. Modeling of this coupling is very important to understand the brain function but it is at the same time very complex due to the complexity of the involved phenomena. Many studies have reported a time delay between the neural activity and the cerebral blood flow, which has been described by adding a delay parameter in some of the existing models. An alternative approach is proposed in this paper, where a fractional system is used to model the neurovascular coupling. Thanks to its nonlocal property, a fractional derivative is suitable for modeling the phenomena with delay. The proposed model is coupled with the first version of the well-known balloon model, which relates the cerebral blood flow to the Blood Oxygen Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). Through some numerical simulations, the properties of the fractional model are explained and some preliminary comparisons to a real BOLD data set are provided. © 2014 IEEE.
Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex
Haverkate, Lucas A.; Zbiri, Mohamed; Johnson, Mark R.; Carter, Elizabeth; Kotlewski, Arek; Picken, S.; Mulder, Fokko M.; Kearley, Gordon J.
2014-01-01
Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10-2 electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements [L. A. Haverkate, M. Zbiri, M. R. Johnson, B. Deme, H. J. M. de Groot, F. Lefeber, A. Kotlewski, S. J. Picken, F. M. Mulder, and G. J. Kearley, J. Phys. Chem. B 116, 13098 (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems.
Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex
Energy Technology Data Exchange (ETDEWEB)
Haverkate, Lucas A.; Mulder, Fokko M. [Reactor Institute Delft, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Zbiri, Mohamed, E-mail: zbiri@ill.fr; Johnson, Mark R. [Institut Laue Langevin, 38042 Grenoble Cedex 9 (France); Carter, Elizabeth [Vibrational Spectroscopy Facility, School of Chemistry, The University of Sydney, NSW 2008 (Australia); Kotlewski, Arek; Picken, S. [ChemE-NSM, Faculty of Chemistry, Delft University of Technology, 2628BL/136 Delft (Netherlands); Kearley, Gordon J. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Menai, NSW 2234 (Australia)
2014-01-07
Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10{sup −2} electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements [L. A. Haverkate, M. Zbiri, M. R. Johnson, B. Deme, H. J. M. de Groot, F. Lefeber, A. Kotlewski, S. J. Picken, F. M. Mulder, and G. J. Kearley, J. Phys. Chem. B 116, 13098 (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems.
Vibronic intensities for Er{sup 3+} in Cs{sub 2} NaErCl{sub 6}
Energy Technology Data Exchange (ETDEWEB)
Acevedo, R.; Navarro, G. [Departamento de Quimica Basica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Beauchef 850, Casilla 2777, Santiago (Chile); Meruane, T. [Universidad Metropolitana de Ciencias y Educacion, Av. Jose Pedro Alessandri 774, Casilla 147-C Santiago (Chile)
2001-07-01
In this current study, we have undertaken vibronic intensity calculations for the absorptions (({sup 4}I{sub 15/2}) {gamma}{sub k}) {yields} (({sup 4}I{sub 13/2}) {gamma}{sub l}) of the Er{sup 3+} in the Cs{sub 2}NaErCl{sub 6} elpasolite type system. This system is extremely complicated to handle from both a theoretical and an experimental viewpoints. This theoretical work shows that over an energy range of about 400 cm{sup -1}, a substantial amount of transitions are likely to take place (about 100 transitions; twenty five of them are magnetic dipole allowed and seventy five are vibronically allowed). It is then a formidable task to identify and assign all of these transitions in a non-ambiguous way. Also the experimental evidence available for these absorptions is related to a total of about twenty lines in the luminescence spectrum of this system. The spectrum itself is very challenging and the superposition of spectral features is most likely to occur. A careful analysis of the calculated vibronic intensities and overall oscillator strengths for the various transitions indicates that the current model used is both flexible and appropriate to deal with this kind of systems. In a forthcoming paper, we will examine the rather unusual high intensity associated with the (({sup 4}I{sub 15/2}) {gamma}{sub k}) {yields} (({sup 4}S{sub 3/2}) {gamma}{sub l}) excitations. (Author)
Coupled wave model for large magnet coils
Gabriel, G. J.
1980-01-01
A wave coupled model based on field theory is evolved for analysis of fast electromagnetic transients on superconducting coils. It is expected to play a useful role in the design of protection methods against damage due to high voltages or any adverse effects that might arise from unintentional transients. The significant parameters of the coil are identified to be the turn to turn wave coupling coefficients and the travel time of an electromagnetic disturbance around a single turn. Unlike circuit theoretic inductor, the coil response evolves in discrete steps having durations equal to this travel time. It is during such intervals that high voltages are likely to occur. The model also bridges the gap between the low and high ends of the frequency spectrum.
Coupled atmosphere-wildland fire modelling
Directory of Open Access Journals (Sweden)
Jacques Henri Balbi
2009-10-01
Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.
Modeling of Coupled Nano-Cavity Lasers
DEFF Research Database (Denmark)
Skovgård, Troels Suhr
Modeling of nanocavity light emitting semiconductor devices is done using the semiconductor laser rate equations with spontaneous and stimulated emission terms modified for Purcell enhanced recombination. The modified terms include details about the optical and electronic density-of-states and it......Modeling of nanocavity light emitting semiconductor devices is done using the semiconductor laser rate equations with spontaneous and stimulated emission terms modified for Purcell enhanced recombination. The modified terms include details about the optical and electronic density......-of-states relative to the optical density-of-states. The low effective Purcell eect for quantum well devices limits the highest possible modulation bandwidth to a few tens of gigahertz, which is comparable to the performance of conventional diode lasers. Compared to quantum well devices, quantum dot devices have...... is useful for design of coupled systems. A tight-binding description for coupled nanocavity lasers is developed and employed to investigate the phase-locking behavior for the system of two coupled cavities. Phase-locking is found to be critically dependent on exact parameter values and to be dicult...
A Tightly Coupled Non-Equilibrium Magneto-Hydrodynamic Model for Inductively Coupled RF Plasmas
2016-02-29
Journal Article 3. DATES COVERED (From - To) 12 May 2015 – 06 Oct 2015 4. TITLE AND SUBTITLE A Tightly Coupled Non-Equilibrium Magneto- Hydrodynamic ...development a tightly coupled magneto- hydrodynamic model for Inductively Coupled Radio- Frequency (RF) Plasmas. Non Local Thermodynamic Equilibrium (NLTE... hydrodynamic model for Inductively Coupled RF Plasmas A. Munafò,1, a) S. A. Alfuhaid,1, b) J.-L. Cambier,2, c) and M. Panesi1, d) 1)Department of
Energy Technology Data Exchange (ETDEWEB)
Bizimana, Laurie A.; Brazard, Johanna; Carbery, William P.; Gellen, Tobias; Turner, Daniel B., E-mail: dturner@nyu.edu [Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003 (United States)
2015-10-28
Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with the vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.
Bizimana, Laurie A; Brazard, Johanna; Carbery, William P; Gellen, Tobias; Turner, Daniel B
2015-10-28
Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with the vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.
Vibronic excitation of single molecules: a new technique for studying low-temperature dynamics.
Kiraz, Alper; Ehrl, Moritz; Hellriegel, Christian; Bräuchle, Christoph; Zumbusch, Andreas
2005-05-01
Herein, we present vibronic excitation and detection of purely electronic zero-phonon lines (ZPL) of single molecules as a new tool for investigating dynamics at cryogenic temperatures. Applications of this technique to study crystalline and amorphous matrix materials are presented. In the crystalline environment, spectrally stable ZPLs are observed at moderate excitation powers. By contrast, investigations at higher excitation intensities reveal the opening of local degrees of freedom and spectral jumps, which we interpret as the observation of elementary steps in the melting of a crystal. We compare these results to spectral single-molecule trajectories recorded in a polymer. The way in which much more complicated spectral features can be analysed is shown. Surprisingly, pronounced spectral shifts on a previously not accessible large energy scale are observed, which are hard to reconcile with the standard two-level model system used to describe low-temperature dynamics in disordered systems.
The standard model coupled to quantum gravitodynamics
Energy Technology Data Exchange (ETDEWEB)
Aldabe, Fermin
2017-01-15
We show that the renormalizable SO(4) x U(1) x SU(2) x SU(3) Yang-Mills coupled to matter and the Higgs field fits all the experimentally observed differential cross sections known in nature. This extended Standard Model reproduces the experimental gravitational differential cross sections without resorting to the graviton field and instead by exchanging SO(4) gauge fields. By construction, each SO(4) generator in quantum gravitodynamics does not commute with the Dirac gamma matrices. This produces additional interactions absent to non-Abelian gauge fields in the Standard Model. The contributions from these new terms yield differential cross sections consistent with the Newtonian and post-Newtonian interactions derived from General Relativity. Dimensional analysis of the Lagrangian shows that all its terms have total dimensionality four or less and therefore that all physical quantities in the theory renormalize by finite amounts. These properties make QGD the only renormalizable four-dimensional theory describing gravitational interactions. (orig.)
Clemente-Juan, Juan Modesto; Palii, Andrew; Coronado, Eugenio; Tsukerblat, Boris
2016-08-09
In this article, we focus on the electron-vibrational problem of the tetrameric mixed-valence (MV) complexes proposed for implementation as four-dot molecular quantum cellular automata (mQCA).1 Although the adiabatic approximation explored in ref 2 is an appropriate tool for the qualitative analysis of the basic characteristics of mQCA, like vibronic trapping of the electrons encoding binary information and cell-cell response, it loses its accuracy providing moderate vibronic coupling and fails in the description of the discrete pattern of the vibronic levels. Therefore, a precise solution of the quantum-mechanical vibronic problem is of primary importance for the evaluation of the shapes of the electron transfer optical absorption bands and quantitative analysis of the main parameters of tetrameric quantum cells. Here, we go beyond the Born-Oppenheimer paradigm and present a solution of the quantum-mechanical pseudo Jahn-Teller (JT) vibronic problem in bielectronic MV species (exemplified by the tetra-ruthenium complexes) based on the recently developed symmetry-assisted approach.3,4 The mathematical approach to the vibronic eigenproblem takes into consideration the point symmetry basis, and therefore, the total matrix of the JT Hamiltonian is blocked to the maximum extent. The submatrices correspond to the irreducible representations (irreps) of the point group. With this tool, we also extend the theory of the mQCA cell beyond the limit of prevailing Coulomb repulsion in the electronic pair (adopted in ref 2), and therefore, the general pseudo-JT problems for spin-singlet ((1)B1g, 2(1)A1g, (1)B2g, (1)Eu) ⊗ (b1g + eu) and spin-triplet states ((3)A2g, (3)B1g, 2(3)Eu) ⊗ (b1g + eu) in a square-planar bielectronic system are solved. The obtained symmetry-adapted electron-vibrational functions are employed for the calculation of the profiles (shape functions) of the charge transfer absorption bands in the tetrameric MV complexes and for the discussion of the
On coupling global biome models with climate models
Claussen, M.
1994-01-01
The BIOME model of Prentice et al. (1992; J. Biogeogr. 19: 117-134), which predicts global vegetation patterns in equilibrium with climate, was coupled with the ECHAM climate model of the Max-Planck-Institut fiir Meteorologie, Hamburg, Germany. It was found that incorporation of the BIOME model into ECHAM, regardless at which frequency, does not enhance the simulated climate variability, expressed in terms of differences between global vegetation patterns. Strongest changes are seen only betw...
Coupled wake boundary layer model of wind-farms
Stevens, Richard Johannes Antonius Maria; Gayme, Dennice F.; Meneveau, Charles
2015-01-01
We present and test a coupled wake boundary layer (CWBL) model that describes the distribution of the power output in a wind-farm. This model couples the traditional, industry-standard wake model approach with a “top-down” model for the overall wind-farm boundary layer structure. The wake model
Real-time observation of multi-mode vibronic coherence in pentafluoropyridine
Kus, J. A.; Hüter, O.; Temps, F.
2017-07-01
The ultrafast dynamics of pentafluoropyridine in the 1 1B2 (ππ*) electronic state excited at λpump = 255 nm is investigated by femtosecond time-resolved time-of-flight mass spectrometry and photoelectron imaging spectroscopy. A pronounced, long-lived, and complex periodic modulation of the transient ion yield signal with contributions by four distinct frequency components, 72 cm-1, 144 cm-1, 251 cm-1, and 281 cm-1, is observed for up to 9 ps. The recorded photoelectron images display a spectral band from the excited 1 1B2 (ππ*) state only in the oscillation maxima; the signal is strongly reduced in the oscillation minima. Supported by electronic structure calculations at the RI-SCS-CC2 and XMCQDPT2 levels of theory, the oscillating components of the signal are identified as frequencies of b1 symmetry coupling modes in a vibronic coherence of the 1 1B2 (ππ*) and 1 1A2 (πσ*) electronic states. The optical excitation initiates regular and periodic wavepacket motion along those out-of-plane modes. In the distorted molecular structure, the initially excited state acquires substantial πσ* character that modulates the transition dipole moment for ionization and results in the observed oscillations.
Unification of gauge couplings in radiative neutrino mass models
DEFF Research Database (Denmark)
Hagedorn, Claudia; Ohlsson, Tommy; Riad, Stella
2016-01-01
), none of the models leads to gauge coupling unification. Regarding the scale of unification, we find values between 1014 GeV and 1016 GeV for models belonging to class (I) without dark matter, whereas models in class (I) with dark matter as well as models of class (II) prefer values in the range 5......We investigate the possibility of gauge coupling unification in various radiative neutrino mass models, which generate neutrino masses at one- and/or two-loop level. Renormalization group running of gauge couplings is performed analytically and numerically at one- and two-loop order, respectively...... masses at one-loop level and (III) models with particles in the adjoint representation of SU(3). In class (I), gauge couplings unify in a few models and adding dark matter amplifies the chances for unification. In class (II), about a quarter of the models admits gauge coupling unification. In class (III...
Constable, E.; Ballou, R.; Robert, J.; Decorse, C.; Brubach, J.-B.; Roy, P.; Lhotel, E.; Del-Rey, L.; Simonet, V.; Petit, S.; deBrion, S.
2017-01-01
The origin of quantum fluctuations responsible for the spin liquid state in Tb2Ti2O7 has remained a long-standing problem. By synchrotron-based terahertz measurements, we show evidence of strong coupling between the magnetic and lattice degrees of freedom that provides a path to the quantum melting process. As revealed by hybrid crystal electric field-phonon excitations that appear at 0.67 THz below 200 K, and around 0.42 THz below 50 K, the double vibronic process is unique for Tb3 + in the titanate family due to adequate energy matching and strong quadrupolar moments. The results suggest that lattice motion can indeed be the driving force behind spin flips within the hybridized ground and first excited states, promoting quantum terms in the effective Hamiltonian that describes Tb2Ti2O7 .
Coupling Climate Models and Forward-Looking Economic Models
Judd, K.; Brock, W. A.
2010-12-01
Authors: Dr. Kenneth L. Judd, Hoover Institution, and Prof. William A. Brock, University of Wisconsin Current climate models range from General Circulation Models (GCM’s) with millions of degrees of freedom to models with few degrees of freedom. Simple Energy Balance Climate Models (EBCM’s) help us understand the dynamics of GCM’s. The same is true in economics with Computable General Equilibrium Models (CGE’s) where some models are infinite-dimensional multidimensional differential equations but some are simple models. Nordhaus (2007, 2010) couples a simple EBCM with a simple economic model. One- and two- dimensional ECBM’s do better at approximating damages across the globe and positive and negative feedbacks from anthroprogenic forcing (North etal. (1981), Wu and North (2007)). A proper coupling of climate and economic systems is crucial for arriving at effective policies. Brock and Xepapadeas (2010) have used Fourier/Legendre based expansions to study the shape of socially optimal carbon taxes over time at the planetary level in the face of damages caused by polar ice cap melt (as discussed by Oppenheimer, 2005) but in only a “one dimensional” EBCM. Economists have used orthogonal polynomial expansions to solve dynamic, forward-looking economic models (Judd, 1992, 1998). This presentation will couple EBCM climate models with basic forward-looking economic models, and examine the effectiveness and scaling properties of alternative solution methods. We will use a two dimensional EBCM model on the sphere (Wu and North, 2007) and a multicountry, multisector regional model of the economic system. Our aim will be to gain insights into intertemporal shape of the optimal carbon tax schedule, and its impact on global food production, as modeled by Golub and Hertel (2009). We will initially have limited computing resources and will need to focus on highly aggregated models. However, this will be more complex than existing models with forward
Evaluating the suitability of coupled biophysical models for fishery management
Hinrichsen, H.H.; Dickey-Collas, M.; Huret, M.; Peck, M.A.
2011-01-01
The potential role of coupled biophysical models in enhancing the conservation, management, and recovery of fish stocks is assessed, with emphasis on anchovy, cod, herring, and sprat in European waters. The assessment indicates that coupled biophysical models are currently capable of simulating
Tinamit: Making coupled system dynamics models accessible to stakeholders
Malard, Julien; Inam Baig, Azhar; Rojas Díaz, Marcela; Hassanzadeh, Elmira; Adamowski, Jan; Tuy, Héctor; Melgar-Quiñonez, Hugo
2017-04-01
Model coupling is increasingly used as a method of combining the best of two models when representing socio-environmental systems, though barriers to successful model adoption by stakeholders are particularly present with the use of coupled models, due to their high complexity and typically low implementation flexibility. Coupled system dynamics - physically-based modelling is a promising method to improve stakeholder participation in environmental modelling while retaining a high level of complexity for physical process representation, as the system dynamics components are readily understandable and can be built by stakeholders themselves. However, this method is not without limitations in practice, including 1) inflexible and complicated coupling methods, 2) difficult model maintenance after the end of the project, and 3) a wide variety of end-user cultures and languages. We have developed the open-source Python-language software tool Tinamit to overcome some of these limitations to the adoption of stakeholder-based coupled system dynamics - physically-based modelling. The software is unique in 1) its inclusion of both a graphical user interface (GUI) and a library of available commands (API) that allow users with little or no coding abilities to rapidly, effectively, and flexibly couple models, 2) its multilingual support for the GUI, allowing users to couple models in their preferred language (and to add new languages as necessary for their community work), and 3) its modular structure allowing for very easy model coupling and modification without the direct use of code, and to which programming-savvy users can easily add support for new types of physically-based models. We discuss how the use of Tinamit for model coupling can greatly increase the accessibility of coupled models to stakeholders, using an example of a stakeholder-built system dynamics model of soil salinity issues in Pakistan coupled with the physically-based soil salinity and water flow model
Coupling of the Models of Human Physiology and Thermal Comfort
Pokorny, J.; Jicha, M.
2013-04-01
A coupled model of human physiology and thermal comfort was developed in Dymola/Modelica. A coupling combines a modified Tanabe model of human physiology and thermal comfort model developed by Zhang. The Coupled model allows predicting the thermal sensation and comfort of both local and overall from local boundary conditions representing ambient and personal factors. The aim of this study was to compare prediction of the Coupled model with the Fiala model prediction and experimental data. Validation data were taken from the literature, mainly from the validation manual of software Theseus-FE [1]. In the paper validation of the model for very light physical activities (1 met) indoor environment with temperatures from 12 °C up to 48 °C is presented. The Coupled model predicts mean skin temperature for cold, neutral and warm environment well. However prediction of core temperature in cold environment is inaccurate and very affected by ambient temperature. Evaluation of thermal comfort in warm environment is supplemented by skin wettedness prediction. The Coupled model is designed for non-uniform and transient environmental conditions; it is also suitable simulation of thermal comfort in vehicles cabins. The usage of the model is limited for very light physical activities up to 1.2 met only.
Coupling of the Models of Human Physiology and Thermal Comfort
Directory of Open Access Journals (Sweden)
Jicha M.
2013-04-01
Full Text Available A coupled model of human physiology and thermal comfort was developed in Dymola/Modelica. A coupling combines a modified Tanabe model of human physiology and thermal comfort model developed by Zhang. The Coupled model allows predicting the thermal sensation and comfort of both local and overall from local boundary conditions representing ambient and personal factors. The aim of this study was to compare prediction of the Coupled model with the Fiala model prediction and experimental data. Validation data were taken from the literature, mainly from the validation manual of software Theseus–FE [1]. In the paper validation of the model for very light physical activities (1 met indoor environment with temperatures from 12 °C up to 48 °C is presented. The Coupled model predicts mean skin temperature for cold, neutral and warm environment well. However prediction of core temperature in cold environment is inaccurate and very affected by ambient temperature. Evaluation of thermal comfort in warm environment is supplemented by skin wettedness prediction. The Coupled model is designed for non-uniform and transient environmental conditions; it is also suitable simulation of thermal comfort in vehicles cabins. The usage of the model is limited for very light physical activities up to 1.2 met only.
The coupling of Poisson sigma models to topological backgrounds
Energy Technology Data Exchange (ETDEWEB)
Rosa, Dario [School of Physics, Korea Institute for Advanced Study,Seoul 02455 (Korea, Republic of)
2016-12-13
We extend the coupling to the topological backgrounds, recently worked out for the 2-dimensional BF-model, to the most general Poisson sigma models. The coupling involves the choice of a Casimir function on the target manifold and modifies the BRST transformations. This in turn induces a change in the BRST cohomology of the resulting theory. The observables of the coupled theory are analyzed and their geometrical interpretation is given. We finally couple the theory to 2-dimensional topological gravity: this is the first step to study a topological string theory in propagation on a Poisson manifold. As an application, we show that the gauge-fixed vectorial supersymmetry of the Poisson sigma models has a natural explanation in terms of the theory coupled to topological gravity.
Affine group formulation of the Standard Model coupled to gravity
Chou, Ching-Yi; Soo, Chopin
2013-01-01
Using the affine group formalism, we perform a nonperturbative quantization leading to the construction of elements of a physical Hilbert space for full, Lorentzian quantum gravity coupled to the Standard Model in four spacetime dimensions. This paper constitutes a first step toward understanding the phenomenology of quantum gravitational effects stemming from a consistent treatment of minimal couplings to matter.
Finite difference methods for coupled flow interaction transport models
Directory of Open Access Journals (Sweden)
Shelly McGee
2009-04-01
Full Text Available Understanding chemical transport in blood flow involves coupling the chemical transport process with flow equations describing the blood and plasma in the membrane wall. In this work, we consider a coupled two-dimensional model with transient Navier-Stokes equation to model the blood flow in the vessel and Darcy's flow to model the plasma flow through the vessel wall. The advection-diffusion equation is coupled with the velocities from the flows in the vessel and wall, respectively to model the transport of the chemical. The coupled chemical transport equations are discretized by the finite difference method and the resulting system is solved using the additive Schwarz method. Development of the model and related analytical and numerical results are presented in this work.
Plasma edge modelling with ICRF coupling
Directory of Open Access Journals (Sweden)
Zhang Wei
2017-01-01
Full Text Available The physics of Radio-Frequency (RF wave heating in the Ion Cyclotron Range of Frequencies (ICRF in the core plasmas of fusion devices are relatively well understood while those in the Scrape-Off Layer (SOL remain still unresolved. This paper is dedicated to study the ICRF interactions with the plasma edge, mainly from the theoretical and numerical point of view, in particular with the 3D edge plasma fluid and neutral transport code EMC3-EIRENE and various wave codes. Here emphasis is given to the improvement of ICRF coupling with local gas puffing and to the ICRF induced density convection in the SOL.
Plasma edge modelling with ICRF coupling
Zhang, Wei; Coster, David; Feng, Yuhe; Lunt, Tilmann; Aguiam, Diogo; Bilato, Roberto; Bobkov, Volodymyr; Jacquot, Jonathan; Jacquet, Philippe; Lerche, Ernesto; Noterdaeme, Jean-Marie; Tierens, Wouter
2017-10-01
The physics of Radio-Frequency (RF) wave heating in the Ion Cyclotron Range of Frequencies (ICRF) in the core plasmas of fusion devices are relatively well understood while those in the Scrape-Off Layer (SOL) remain still unresolved. This paper is dedicated to study the ICRF interactions with the plasma edge, mainly from the theoretical and numerical point of view, in particular with the 3D edge plasma fluid and neutral transport code EMC3-EIRENE and various wave codes. Here emphasis is given to the improvement of ICRF coupling with local gas puffing and to the ICRF induced density convection in the SOL.
Coupling a Basin Modeling and a Seismic Code using MOAB
Yan, Mi
2012-06-02
We report on a demonstration of loose multiphysics coupling between a basin modeling code and a seismic code running on a large parallel machine. Multiphysics coupling, which is one critical capability for a high performance computing (HPC) framework, was implemented using the MOAB open-source mesh and field database. MOAB provides for code coupling by storing mesh data and input and output field data for the coupled analysis codes and interpolating the field values between different meshes used by the coupled codes. We found it straightforward to use MOAB to couple the PBSM basin modeling code and the FWI3D seismic code on an IBM Blue Gene/P system. We describe how the coupling was implemented and present benchmarking results for up to 8 racks of Blue Gene/P with 8192 nodes and MPI processes. The coupling code is fast compared to the analysis codes and it scales well up to at least 8192 nodes, indicating that a mesh and field database is an efficient way to implement loose multiphysics coupling for large parallel machines.
Effect of molecular weight on the vibronic structure of a diketopyrrolopyrrole polymer
Hayes, Sophia C.
2016-09-27
Resonance Raman Spectroscopy (RRS) is employed in this study to examine the influence of molecular weight on the optical response of a diketopyrrolopyrrole polymer (DPP-TT-T) in solution. The vibronic structure observed for the ground state absorption of this polymer is found to vary with molecular weight and solvent. Resonance Raman Intensity Analysis (RRIA) revealed that the absorption spectra can be described by at least two dipole-allowed transitions and the vibronic structure variation is due to differing contributions from linear and curved segments of the polymer.
Analysis of vibronic interactions in the molecules of cross-conjugated ketones
Directory of Open Access Journals (Sweden)
Kompaneez V.V.
2017-01-01
Full Text Available We have done quantitative analysis of vibronic parameters of two cross-conjugated δ-dimethylaminoketones. The research shows the influence of С-N and C=O bonds in the rings, and the radicals with nitro compounds on the vibronic parameters of characteristic bands, which describe the state (vibrations, types of deformation under excitation of the phenyl ring and the polyene bridge. Results described impact of the substituent’s nature on the parameters of intra- and intermolecular interactions presents for the studied compounds.
Model of coupling discharges into spacecraft structures
Woods, A. J.; Treadway, M. J.; Grismore, R.; Leadon, R. E.; Flanagan, T.; Wenaas, E. P.
1980-01-01
The calculated results of a semiempirical model for electron-caused electromagnetic pulse (ECEMP) are compared to the experimental data for three spacecraft geometries. The appropriateness of certain model assumptions which have been employed in the absence of a microscopic theory for dielectric breakdown and associated electron blowoff is discussed. Results are limited to the exterior response of spacecraft structures, although neither the model nor the experiments were limited to the outside problem. Rationales for model assumptions are provided.
Modeling Pancake Formation with a Coupled Wave-Ice Model
Veeramony, J.; Orzech, M.; Shi, F.; Bateman, S. P.; Calantoni, J.
2016-12-01
Recent results from the ONR-sponsored Arctic Sea State DRI cruise (Thomson et al., 2016, EOS, in press) suggest that small-scale pancake ice formation is an important process in the initial recovery and refreezing of the Arctic pack ice each autumn. Ocean surface waves and ambient temperature play significant roles in shaping and/or limiting the pancake growth patterns, which may either facilitate or delay the recovery of the ice pack. Here we apply a phase-resolving, coupled wave-ice system, consisting of a CFD wave model (NHWAVE) and a discrete-element ice model (LIGGGHTS), to investigate the formation processes of pancake ice under different conditions. A series of simulations is run, each beginning with a layer of disconnected ice particles floating on the ocean surface. Wave conditions and ice bonding properties are varied to examine the effects of mild versus stormy conditions, wind waves versus swell, and warmer versus colder temperatures. Model runs are limited to domains of O(1 sq km). Initial tests have shown some success in replicating qualitative results from the Sea State cruise, including the formation of irregularly shaped pancakes from the "frazil" ice layer, changes in formation processes caused by varying ambient temperature (represented through variations in ice bonding strength), occasional rafting of one pancake on top of another, and increased wave attenuation as pancakes grow larger.
Light weakly coupled axial forces: models, constraints, and projections
Kahn, Yonatan; Krnjaic, Gordan; Mishra-Sharma, Siddharth; Tait, Tim M. P.
2017-05-01
We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in π0 and 8Be∗ decay.
Nuclear Hybrid Energy System Modeling: RELAP5 Dynamic Coupling Capabilities
Energy Technology Data Exchange (ETDEWEB)
Piyush Sabharwall; Nolan Anderson; Haihua Zhao; Shannon Bragg-Sitton; George Mesina
2012-09-01
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.
Becucci, M.; Lakin, N. M.; Pietraperzia, G.; Castellucci, E.; Bréchignac, Ph.; Coutant, B.; Hermine, P.
1999-05-01
We report two independent sets of experimental spectroscopic data which both contain information about the vibrational dynamics occurring in the aniline-neon van der Waals complex in its S1 electronically excited state. The high resolution excitation spectra of the three vibronic bands, 6a01¯, I02¯, and 101¯, of the S1←S0 transition, exhibit lifetime broadening with respect to transitions to the corresponding states in the aniline monomer. The dispersed emission spectra taken under excitation of the same three vibronic bands give access to both the distribution of aniline monomer states produced by vibrational predissociation of the complex and to the rates at which this dynamics proceeds. The overall results are discussed in a consistent way, with emphasis being given to the role of the coupling between the intramolecular and the intermolecular vibrational states. In the case of I02¯ excitation, it is shown that this coupling is reflected in the shape of the van der Waals wavefunction, as accessed through the analysis of the high resolution spectra [M. Becucci, G. Pietraperzia, N. M. Lakin, E. Castellucci, Ph. Bréchignac, Chem. Phys. Lett. 260, 87 (1996).].
Solutions of several coupled discrete models in terms of Lamé ...
Indian Academy of Sciences (India)
coupled Salerno model, (iii) coupled saturated discrete nonlinear Schrödinger equation. (DNLSE), (iv) coupled φ6 model and (v) coupled φ4 model. We also show that unlike the continuum field theory models, many of the discrete coupled field theory models possess an even broader class of exact solutions. Moreover, we ...
Solutions of several coupled discrete models in terms of Lamé ...
Indian Academy of Sciences (India)
Coupled discrete models are ubiquitous in a variety of physical contexts. We provide an extensive set of exact quasiperiodic solutions of a number of coupled discrete models in terms of Lamé polynomials of arbitrary order. The models discussed are: coupled Salerno model,; coupled Ablowitz–Ladik model,; coupled 4 ...
The response of a (3)He Fermi liquid droplet to vibronic excitation of an embedded glyoxal molecule.
Benedek, Giorgio; Hizhnyakov, Vladimir; Toennies, J Peter
2014-08-21
The zero-phonon line (ZPL) and the sideband in the vibronic spectrum of a single glyoxal molecule inside a (3)He droplet are analyzed within the framework of the Lax formalism. The new theory takes full account of the coupling of the molecule to the single particle-hole (PH) and collective excitations of the doped Fermionic droplet. The effect on the coupling of the wavevector dependence of the effective (3)He mass and the large local density of the first (3)He shell, resulting from the interaction with the chromophore, are also included in the theory. By fitting of a coupling parameter and the phase factor between the PH and collective response functions, the shape and relative intensity of the observed ZPL and its slowly decreasing multiexcitation sideband are well-reproduced. The new theory is consistent with the previous explanation of the surprisingly sharp phonon line superimposed on the sideband in terms of the dense first (3)He shell, which acts as a Helmholtz resonator for the zero sound of the droplet.
Tremblay, Jean Christophe
2013-06-28
A model for treating excitation and relaxation of adsorbates at metallic surfaces induced by non-adiabatic coupling is developed. The derivation is based on the concept of resonant electron transfer, where the adsorbate serves as a molecular bridge for the inelastic transition between an electron source and a sink. In this picture, energy relaxation and scanning tunneling microscopy (STM) at metallic surfaces are treated on an equal footing as a quasi-thermal process. The model goes beyond the local harmonic approximation and allows for an unbiased description of floppy systems with multiple potential wells. Further, the limitation of the product ansatz for the vibronic wave function to include the position-dependence of the non-adiabatic couplings is avoided by explicitly enforcing detailed balance. The theory is applied to the excitation of hydrogen on palladium, which has multiple local potential minima connected by low energy barriers. The main aspects investigated are the lifetimes of adsorbate vibrations in different adsorption sites, as well as the dependence of the excitation, response, and transfer rates on an applied potential bias. The excitation and relaxation simulations reveal intricate population dynamics that depart significantly from the simplistic tunneling model in a truncated harmonic potential. In particular, the population decay from an initially occupied local minimum induced by the contact with an STM tip is found to be better described by a double exponential. The two rates are interpreted as a response to the system perturbation and a transfer rate following the perturbation. The transfer rate is found to obey a power law, as was the case in previous experimental and theoretical work.
Vibronic emission transitions of gadolinium(III) in sodium lanthanum sulfate hydrate
Blasse, G.
1987-01-01
Cooperative vibronic emission transitions are reported for Gd3+ in NaLa(SO4)2H2O. They involve the electronic 6P → 8S transition on the Gd3+ ion and the asymmetric-valence-vibrational transition on the SO42− anion and the H2O molecule which are both coordinated to the Gd3+ ion.
To Be or Not to Be Symmetric: That is the Question for Potentially Active Vibronic Modes
Tyler, Sarah F.; Judkins, Eileen C.; Morozov, Dmitry; Borca, Carlos H.; Slipchenko, Lyudmila V.; McMillin, David R.
2017-01-01
Electronic spectra often exhibit vibronic structure when vibrational and electronic transitions occur in concert. Theory reveals (1) that orbital symmetry considerations determine specific roles played by the nuclear degrees of freedom and (2) that the vibrational excitation is often highly regiospecific, that is, attributable to an identifiable…
Strong Local-Nonlocal Coupling for Integrated Fracture Modeling
Energy Technology Data Exchange (ETDEWEB)
Littlewood, David John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silling, Stewart A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, John A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seleson, Pablo D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bond, Stephen D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parks, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, Daniel Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burnett, Damon J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ostien, Jakob [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Gunzburger, Max [Florida State Univ., Tallahassee, FL (United States)
2015-09-01
Peridynamics, a nonlocal extension of continuum mechanics, is unique in its ability to capture pervasive material failure. Its use in the majority of system-level analyses carried out at Sandia, however, is severely limited, due in large part to computational expense and the challenge posed by the imposition of nonlocal boundary conditions. Combined analyses in which peridynamics is em- ployed only in regions susceptible to material failure are therefore highly desirable, yet available coupling strategies have remained severely limited. This report is a summary of the Laboratory Directed Research and Development (LDRD) project "Strong Local-Nonlocal Coupling for Inte- grated Fracture Modeling," completed within the Computing and Information Sciences (CIS) In- vestment Area at Sandia National Laboratories. A number of challenges inherent to coupling local and nonlocal models are addressed. A primary result is the extension of peridynamics to facilitate a variable nonlocal length scale. This approach, termed the peridynamic partial stress, can greatly reduce the mathematical incompatibility between local and nonlocal equations through reduction of the peridynamic horizon in the vicinity of a model interface. A second result is the formulation of a blending-based coupling approach that may be applied either as the primary coupling strategy, or in combination with the peridynamic partial stress. This blending-based approach is distinct from general blending methods, such as the Arlequin approach, in that it is specific to the coupling of peridynamics and classical continuum mechanics. Facilitating the coupling of peridynamics and classical continuum mechanics has also required innovations aimed directly at peridynamic models. Specifically, the properties of peridynamic constitutive models near domain boundaries and shortcomings in available discretization strategies have been addressed. The results are a class of position-aware peridynamic constitutive laws for
A Coupled Atmosphere-Ocean-Wave Modeling System
Allard, R. A.; Smith, T.; Rogers, W. E.; Jensen, T. G.; Chu, P.; Campbell, T. J.
2012-12-01
A growing interest in the impacts that large and small scale ocean and atmospheric events (El Niño, hurricanes, etc.) have on weather forecasting has led to the coupling of atmospheric, ocean circulation and ocean wave models. The Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS™ ) consists of the Navy's atmospheric model coupled to the Navy Coastal Ocean Model (NCOM) and the wave models SWAN (Simulating WAves Nearshore) and WAVEWATCH III (WW3™). In a fully coupled mode, COAMPS, NCOM, and SWAN (or WW3) may be integrated concurrently so that currents and water levels, wave-induced stress, bottom drag, Stokes drift current, precipitation, and surface fluxes of heat, moisture, and momentum are exchanged across the air-wave-sea interface. This coupling is facilitated through the Earth System Modeling Framework (ESMF). The ESMF version of COAMPS is being transitioned to operational production centers at the Naval Oceanographic Office and the Fleet Numerical Meteorology and Oceanography Center. Highlights from validation studies for the Florida Straits, Hurricane Ivan and the Adriatic Sea will be presented. COAMPS® is a registered trademark of the Naval Research Laboratory.
Energy demand analytics using coupled technological and economic models
Impacts of a range of policy scenarios on end-use energy demand are examined using a coupling of MARKAL, an energy system model with extensive supply and end-use technological detail, with Inforum LIFT, a large-scale model of the us. economy with inter-industry, government, and c...
On the coupling of benthic and pelagic biogeochemical models
Soetaert, K.E.R.; Middelburg, J.J.; Herman, P.M.J.; Buis, K.
2000-01-01
Mutual interaction of water column and sediment processes is either neglected or only crudely approximated in many biogeochemical models. We have reviewed the approaches to couple benthic and pelagic biogeochemical models. It is concluded that they can be classified into a hierarchical set
Concepts and models of coupled systems
Ertsen, Maurits
2017-04-01
In this paper, I will especially focus on the question of the position of human agency, social networks and complex co-evolutionary interactions in socio-hydrological models. The long term perspective of complex systems' modeling typically focuses on regional or global spatial scales and century/millennium time scales. It is still a challenge to relate correlations in outcomes defined at those longer and larger scales to the causalities at the shorter and smaller scales. How do we move today to the next 1000 years in the same way that our ancestors did move from their today to our present, in the small steps that produce reality? Please note, I am not arguing long term work is not interesting or the like. I just pose the question how to deal with the problem that we employ relations with hindsight that matter to us, but not necessarily to the agents that produced the relations we think we have observed. I would like to push the socio-hydrological community a little into rethinking how to deal with complexity, with the aim to bring together the timescales of humans and complexity. I will provide one or two examples of how larger-scale and longer-term observations on water flows and environmental loads can be broken down into smaller-scale and shorter-term production processes of these same loads.
Service-Oriented Approach to Coupling Earth System Models and Modeling Frameworks
Goodall, J. L.; Saint, K. D.; Ercan, M. B.; Briley, L. J.; Murphy, S.; You, H.; DeLuca, C.; Rood, R. B.
2012-12-01
Modeling water systems often requires coupling models across traditional Earth science disciplinary boundaries. While there has been significant effort within various Earth science disciplines (e.g., atmospheric science, hydrology, and Earth surface dynamics) to create models and, more recently, modeling frameworks, there has been less work on methods for coupling across disciplinary-specific models and modeling frameworks. We present work investigating one possible method for coupling across disciplinary-specific Earth system models and modeling frameworks: service-oriented architectures. In a service-oriented architecture, models act as distinct units or components within a system and are designed to pass well defined messages to consumers of the service. While the approach offers the potential to couple heterogeneous computational models by allowing a high degree of autonomy across models of the Earth system, there are significant scientific and technical challenges to be addressed when coupling models designed for different communities and built for different modeling frameworks. We have addressed some of these challenges through a case study where we coupled a hydrologic model compliant with the OpenMI standard with an atmospheric model compliant with the EMSF standard. In this case study, the two models were coupled through data exchanges of boundary conditions enabled by exposing the atmospheric model as a web service. A discussion of the technical and scientific challenges, some that we have addressed and others that remain open, will be presented including differences in computer architectures, data semantics, and spatial scales between the coupled models.
Energy Technology Data Exchange (ETDEWEB)
Oertling, W.A.; Wu, Weishih; Lopez-Garriga, J.J.; Kim, Younkyoo; Chang, Chi, K. (Michigan State Univ., East Lansing (USA))
1991-01-02
The newly synthesized metalloporphycenes represent a class of molecules that are structural isomers of metalloporphyrins. In particular, the Ni{sup II} and Cu{sup II} complexes of 2,7,12,17-tetrapropylporphycene (NiPPC and CuPPC) display UV-visible absorption and resonance Raman (RR) spectra superficially like those of analogous complexes of octaethylporphyrin (OEP). However, close examination of absorption band positions and spectral shifts caused by metal substitution and ring bromination, as well as relative oscillator strengths, suggest that, unlike those of metalloporphyrins, the {pi} {yields} {pi}* states of NiPPC and CuPPC are adequately defined by one-electron wave functions. Thus, the {pi}-electron configuration interaction that gives rise to Gouterman's Q and B metalloporphyrin excited states is weak in metalloporphycenes. Rather, these novel complexes appear to be a near-perfect example of Platt's long-field molecules. Raman spectra in resonance with the major absorptions of CuPPC show little evidence of Jahn-Teller or Herzber-Teller coupling. Thus, the rich vibronic coupling present in metalloporphyrins giving rise to the celebrated anomalously polarized scattering most likely does not complicate the spectra of metalloporphycenes. Vibrational analyses of RR spectra of specifically deuterated derivatives of NiPPC give some insight into the normal mode compositions.
Fluid coupling in a discrete model of cochlear mechanics.
Elliott, Stephen J; Lineton, Ben; Ni, Guangjian
2011-09-01
A discrete model of cochlear mechanics is introduced that includes a full, three-dimensional, description of fluid coupling. This formulation allows the fluid coupling and basilar membrane dynamics to be analyzed separately and then coupled together with a simple piece of linear algebra. The fluid coupling is initially analyzed using a wavenumber formulation and is separated into one component due to one-dimensional fluid coupling and one comprising all the other contributions. Using the theory of acoustic waves in a duct, however, these two components of the pressure can also be associated with a far field, due to the plane wave, and a near field, due to the evanescent, higher order, modes. The near field components are then seen as one of a number of sources of additional longitudinal coupling in the cochlea. The effects of non-uniformity and asymmetry in the fluid chamber areas can also be taken into account, to predict both the pressure difference between the chambers and the mean pressure. This allows the calculation, for example, of the effect of a short cochlear implant on the coupled response of the cochlea. © 2011 Acoustical Society of America
Validation of coupled atmosphere-fire behavior models
Energy Technology Data Exchange (ETDEWEB)
Bossert, J.E.; Reisner, J.M.; Linn, R.R.; Winterkamp, J.L. [Los Alamos National Lab., NM (United States); Schaub, R. [Dynamac Corp., Kennedy Space Center, FL (United States); Riggan, P.J. [Forest Service, Riverside, CA (United States)
1998-12-31
Recent advances in numerical modeling and computer power have made it feasible to simulate the dynamical interaction and feedback between the heat and turbulence induced by wildfires and the local atmospheric wind and temperature fields. At Los Alamos National Laboratory, the authors have developed a modeling system that includes this interaction by coupling a high resolution atmospheric dynamics model, HIGRAD, with a fire behavior model, BEHAVE, to predict the spread of wildfires. The HIGRAD/BEHAVE model is run at very high resolution to properly resolve the fire/atmosphere interaction. At present, these coupled wildfire model simulations are computationally intensive. The additional complexity of these models require sophisticated methods for assuring their reliability in real world applications. With this in mind, a substantial part of the research effort is directed at model validation. Several instrumented prescribed fires have been conducted with multi-agency support and participation from chaparral, marsh, and scrub environments in coastal areas of Florida and inland California. In this paper, the authors first describe the data required to initialize the components of the wildfire modeling system. Then they present results from one of the Florida fires, and discuss a strategy for further testing and improvement of coupled weather/wildfire models.
Mathematical Modeling of Neuro-Vascular Coupling in Rat Cerebellum
DEFF Research Database (Denmark)
Rasmussen, Tina
measured field potential is used as an indicator of neuronal activity, and the cortical blood flow is measured by means of laser-Doppler flowmetry. Using system identification methods, these measurements have been used to construct and validate parametric mathematical models of the neuro-vascular system....... Mathematical arguments as well as hypotheses about the physiological system have been used to construct the models.......Activity in the neurons called climbing fibers causes blood flow changes. But the physiological mechanisms which mediate the coupling are not well understood. This PhD thesis investigates the mechanisms of neuro-vascular coupling by means of mathematical methods. In experiments, the extracellularly...
Midsummer Drought Pattern simulated by a coupled regional climate model
Martinez-Lopez, Benjamin; Cabos Narvaez, William David; Sein, Dmitry; Quintanar, Arturo
2017-04-01
In this work, a regional climate model of limited area, in both atmospheric and coupled mode, is used to simulate the historical period over a domain including Mexico and Central America. In the atmospheric mode, the REMO atmosphere model is used, while in the coupled simulation, REMO is coupled to the MPI-OM ocean model. In all simulations, REMO is driven at the open boundaries by reanalysis data from ERA-40. Several numerical experiments are performed using three different spatial resolutions (100 km, 50 km, and 25 km). Taylor diagrams of some meteorological and oceanic variables are used to get a quantitative idea of model performance. Additionally, the observed patterns of the Midsummer Drought are compared with the simulated ones. Among the results, it is noted that the coupled model with the highest resolution has the best performance to simulate the observed pattern of the Midsummer Drought. Over the eastern Pacific warm pool region, the coupled simulation generate fields of sea surface temperature, wind, and sea level pressure gradients more consistent with independent observations that those simulated in the atmospheric mode. In particular, the wind strengthened observed in July is well reproduced in the coupled simulation, which lead to higher values of vertically integrated water vapour transport coming from both the eastern tropical Pacific and the Caribbean. Despite the increased atmospheric humidity available above this region, the simulated fluxes are divergent and therefore the precipitation is reduced in July, in agreement with the observations. This July divergence in the vertically integrated water vapour transport is not present in the atmospheric mode.
Hazra, Anirban; Soudackov, Alexander V; Hammes-Schiffer, Sharon
2010-09-30
A theoretical formulation for modeling photoinduced nonequilibrium proton-coupled electron transfer (PCET) reactions in solution is presented. In this formulation, the PCET system is described by donor and acceptor electron-proton vibronic free energy surfaces that depend on a single collective solvent coordinate. Dielectric continuum theory is used to obtain a generalized Langevin equation of motion for this collective solvent coordinate. The terms in this equation depend on the solvent properties, such as the dielectric constants, relaxation time, and molecular moment of inertia, as well as the solute properties characterizing the vibronic surfaces. The ultrafast dynamics following photoexcitation is simulated using a surface hopping method in conjunction with the Langevin equation of motion. This methodology is used to examine a series of model photoinduced PCET systems, where the initial nonequilibrium state is prepared by vertical photoexcitation from the ground electronic state to the donor electronic state. Analysis of the dynamical trajectories provides insight into the interplay between the solvent dynamics and the electron-proton transfer for these types of processes. In addition, these model studies illustrate how the coupling between the electron-proton transfer and the solvent dynamics can be tuned by altering the solute and solvent properties.
Signatures of Herzberg-Teller coupling in three-dimensional electronic spectroscopy
Bizimana, Laurie A.; Carbery, William P.; Gellen, Tobias A.; Turner, Daniel B.
2017-02-01
The coupling between electronic and nuclear variables is a key consideration in molecular dynamics and spectroscopy. However, simulations that include detailed vibronic coupling terms are challenging to perform, and thus a variety of approximations can be used to model and interpret experimental results. Recent work shows that these simplified models can be inadequate. It is therefore important to understand spectroscopic signals that can identify failures of those approximations. Here we use an extended response-function method to simulate coherent three-dimensional electronic spectroscopy (3D ES) and study the sensitivity of this method to the breakdown of the Franck-Condon approximation. The simulations include a coordinate-dependent transition dipole operator that produces nodes, phase shifts, and peak patterns in 3D ES that can be used to identify Herzberg-Teller coupling. Guided by the simulation results, we interpret measurements on a molecular aggregate.
Signatures of Herzberg-Teller coupling in three-dimensional electronic spectroscopy.
Bizimana, Laurie A; Carbery, William P; Gellen, Tobias A; Turner, Daniel B
2017-02-28
The coupling between electronic and nuclear variables is a key consideration in molecular dynamics and spectroscopy. However, simulations that include detailed vibronic coupling terms are challenging to perform, and thus a variety of approximations can be used to model and interpret experimental results. Recent work shows that these simplified models can be inadequate. It is therefore important to understand spectroscopic signals that can identify failures of those approximations. Here we use an extended response-function method to simulate coherent three-dimensional electronic spectroscopy (3D ES) and study the sensitivity of this method to the breakdown of the Franck-Condon approximation. The simulations include a coordinate-dependent transition dipole operator that produces nodes, phase shifts, and peak patterns in 3D ES that can be used to identify Herzberg-Teller coupling. Guided by the simulation results, we interpret measurements on a molecular aggregate.
A Coupled Plasma and Sheath Model for High Density Reactors
Deepak, Bose; Govindan, T. R.; Meyyappan, M.; Arnold, Jim (Technical Monitor)
2001-01-01
We present a coupled plasma and collisionless; sheath model for the simulation of high density plasma processing reactors. Due to inefficiencies in numerical schemes and the resulting computational burden, a coupled multidimensional plasma and sheath simulation has not been possible model for gas mixtures and high density reactors of practical interest. In this work we demonstrate that with a fully implicit algorithm and a refined computational mesh, a self-consistent plasma and sheath simulation is feasible. We discuss the details of the model equations, the importance of ion inertia, and the resulting sheath profiles for argon and chlorine plasmas. We find that at low operating pressures (10-30 mTorr), the charge separation occurs only within a 0.5 mm layer near the surface in a 300 mm inductively coupled plasma etch reactor. A unified model eliminates the use of off-line or loosely coupled sheath models with simplifying assumptions which generally lead to uncertainties in ion flux and sheath electrical properties.
Model reduction for optimization of structural-acoustic coupling problems
DEFF Research Database (Denmark)
Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas
2016-01-01
-acoustic coupling, for which two different approaches to constructing a modal reduction base are discussed. The efficiency and accuracy of the CMS and the MMR methods are strongly model-dependent; in this paper, they are compared for two optimization problems in the hearing aid context, where the MMR technique......Fully coupled structural-acoustic models of complex systems, such as those used in the hearing aid field, may have several hundreds of thousands of nodes. When there is a strong structure-acoustic interaction, performing optimization on one part requires the complete model to be taken into account......, which becomes highly time consuming since many iterations may be required. The use of model reduction techniques to speed up the computations is studied in this work. The Component Mode Synthesis (CMS) method and the Multi-Model Reduction (MMR) method are adapted for problems with structure...
A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas
Energy Technology Data Exchange (ETDEWEB)
Munafò, A., E-mail: munafo@illinois.edu; Alfuhaid, S. A., E-mail: alfuhai2@illinois.edu; Panesi, M., E-mail: mpanesi@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Talbot Laboratory, 104 S. Wright St., Urbana, Illinois 61801 (United States); Cambier, J.-L., E-mail: jean-luc.cambier@us.af.mil [Edwards Air Force Base Research Laboratory, 10 E. Saturn Blvd., Edwards AFB, California 93524 (United States)
2015-10-07
The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.
Simple model with damping of the mode-coupling instability
Energy Technology Data Exchange (ETDEWEB)
Pestrikov, D.V. [AN SSSR, Novosibirsk (Russian Federation). Inst. Yadernoj Fiziki
1996-08-01
In this paper we use a simple model to study the suppression of the transverse mode-coupling instability. Two possibilities are considered. One is due to the damping of particular synchrobetatron modes, and another - due to Landau damping, caused by the nonlinearity of betatron oscillations. (author)
Mutual coupling, channel model, and BER for curvilinear antenna arrays
Huang, Zhiyong
This dissertation introduces a wireless communications system with an adaptive beam-former and investigates its performance with different antenna arrays. Mutual coupling, real antenna elements and channel models are included to examine the system performance. In a beamforming system, mutual coupling (MC) among the elements can significantly degrade the system performance. However, MC effects can be compensated if an accurate model of mutual coupling is available. A mutual coupling matrix model is utilized to compensate mutual coupling in the beamforming of a uniform circular array (UCA). Its performance is compared with other models in uplink and downlink beamforming scenarios. In addition, the predictions are compared with measurements and verified with results from full-wave simulations. In order to accurately investigate the minimum mean-square-error (MSE) of an adaptive array in MC, two different noise models, the environmental and the receiver noise, are modeled. The minimum MSEs with and without data domain MC compensation are analytically compared. The influence of mutual coupling on the convergence is also examined. In addition, the weight compensation method is proposed to attain the desired array pattern. Adaptive arrays with different geometries are implemented with the minimum MSE algorithm in the wireless communications system to combat interference at the same frequency. The bit-error-rate (BER) of systems with UCA, uniform rectangular array (URA) and UCA with center element are investigated in additive white Gaussian noise plus well-separated signals or random direction signals scenarios. The output SINR of an adaptive array with multiple interferers is analytically examined. The influence of the adaptive algorithm convergence on the BER is investigated. The UCA is then investigated in a narrowband Rician fading channel. The channel model is built and the space correlations are examined. The influence of the number of signal paths, number of the
Model reduction for optimization of structural-acoustic coupling problems
DEFF Research Database (Denmark)
Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas
2016-01-01
Fully coupled structural-acoustic models of complex systems, such as those used in the hearing aid field, may have several hundreds of thousands of nodes. When there is a strong structure-acoustic interaction, performing optimization on one part requires the complete model to be taken into account......-acoustic coupling, for which two different approaches to constructing a modal reduction base are discussed. The efficiency and accuracy of the CMS and the MMR methods are strongly model-dependent; in this paper, they are compared for two optimization problems in the hearing aid context, where the MMR technique...... is found to be the most efficient, speeding up the optimizations up to 6 times compared to the full model....
A Coupled Atmospheric and Wave Modeling System for Storm Simulations
DEFF Research Database (Denmark)
Du, Jianting; Larsén, Xiaoli Guo; Bolanos, R.
2015-01-01
to parametrize z0. The results are validated through QuikScat data and point measurements from an open ocean site Ekosk and a coastal, relatively shallow water site Horns Rev. It is found that the modeling system captures in general better strong wind and strong wave characteristics for open ocean condition than......This study aims at improving the simulation of wind and waves during storms in connection with wind turbine design and operations in coastal areas. For this particular purpose, we investigated the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System which couples the Weather...... for the coastal condition. With the current model setup, using high spatial resolution gives better results for strong winds both for the open ocean and coastal sites. The signicant wave height (Hm0) is very sensitive to the model resolution and bathymetry data for the coastal zone. In addition, using Janssen...
Coupled Climate Model Appraisal a Benchmark for Future Studies
Energy Technology Data Exchange (ETDEWEB)
Phillips, T J; AchutaRao, K; Bader, D; Covey, C; Doutriaux, C M; Fiorino, M; Gleckler, P J; Sperber, K R; Taylor, K E
2005-08-22
The Program for Climate Model Diagnosis and Intercomparison (PCMDI) has produced an extensive appraisal of simulations of present-day climate by eleven representative coupled ocean-atmosphere general circulation models (OAGCMs) which were developed during the period 1995-2002. Because projections of potential future global climate change are derived chiefly from OAGCMs, there is a continuing need to test the credibility of these predictions by evaluating model performance in simulating the historically observed climate. For example, such an evaluation is an integral part of the periodic assessments of climate change that are reported by the Intergovernmental Panel on Climate Change. The PCMDI appraisal thus provides a useful benchmark for future studies of this type. The appraisal mainly analyzed multi-decadal simulations of present-day climate by models that employed diverse representations of climate processes for atmosphere, ocean, sea ice, and land, as well as different techniques for coupling these components (see Table). The selected models were a subset of those entered in phase 2 of the Coupled Model Intercomparison Project (CMIP2, Covey et al. 2003). For these ''CMIP2+ models'', more atmospheric or oceanic variables were provided than the minimum requirements for participation in CMIP2. However, the appraisal only considered those climate variables that were supplied from most of the CMIP2+ models. The appraisal focused on three facets of the simulations of current global climate: (1) secular trends in simulation time series which would be indicative of a problematical ''coupled climate drift''; (2) comparisons of temporally averaged fields of simulated atmospheric and oceanic climate variables with available observational climatologies; and (3) correspondences between simulated and observed modes of climatic variability. Highlights of these climatic aspects manifested by different CMIP2+ simulations are briefly
Drift-Scale Coupled Processes (DST and THC Seepage) Models
Energy Technology Data Exchange (ETDEWEB)
P. Dixon
2004-04-05
The purpose of this Model Report (REV02) is to document the unsaturated zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrological-chemical (THC) processes on UZ flow and transport. This Model Report has been developed in accordance with the ''Technical Work Plan for: Performance Assessment Unsaturated Zone'' (Bechtel SAIC Company, LLC (BSC) 2002 [160819]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this Model Report in Section 1.12, Work Package AUZM08, ''Coupled Effects on Flow and Seepage''. The plan for validation of the models documented in this Model Report is given in Attachment I, Model Validation Plans, Section I-3-4, of the TWP. Except for variations in acceptance criteria (Section 4.2), there were no deviations from this TWP. This report was developed in accordance with AP-SIII.10Q, ''Models''. This Model Report documents the THC Seepage Model and the Drift Scale Test (DST) THC Model. The THC Seepage Model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC model is a drift-scale process model relying on the same conceptual model and much of the same input data (i.e., physical, hydrological, thermodynamic, and kinetic) as the THC Seepage Model. The DST THC Model is the primary method for validating the THC Seepage Model. The DST THC Model compares predicted water and gas compositions, as well as mineral alteration patterns, with observed data from the DST. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal-loading conditions, and predict the evolution of mineral alteration and fluid chemistry around potential waste emplacement drifts. The
Coupling model for waves propagating over a porous seabed
Directory of Open Access Journals (Sweden)
C.C. Liao
2015-03-01
Full Text Available The wave–seabed interaction issue is of great importance for the design of foundation around marine infrastructures. Most previous investigations for such a problem have been limited to uncoupled or one-way coupled methods connecting two separated wave and seabed sub models with the continuity of pressures at the seabed surface. In this study, a strongly coupled model was proposed to realize both wave and seabed processes in a same program and to calculate the wave fields and seabed response simultaneously. The information between wave fields and seabed fields were strongly shared and thus results in a more profound investigation of the mechanism of the wave–seabed interaction. In this letter, the wave and seabed models were validated with previous experimental tests. Then, a set of application of present model were discussed in prediction of the wave-induced seabed response. Numerical results show the wave-induced liquefaction area of coupled model is smaller than that of uncoupled model.
Coupled fermion-kink system in Jackiw-Rebbi model
Energy Technology Data Exchange (ETDEWEB)
Amado, A.; Mohammadi, A. [Universidade Federal de Pernambuco, Departamento de Fisica, Recife, PE (Brazil)
2017-07-15
In this paper, we study Jackiw-Rebbi model, in which a massless fermion is coupled to the kink of λφ{sup 4} theory through a Yukawa interaction. In the original Jackiw-Rebbi model, the soliton is prescribed. However, we are interested in the back-reaction of the fermion on the soliton besides the effect of the soliton on the fermion. Also, as a particular example, we consider a minimal supersymmetric kink model in (1 + 1) dimensions. In this case, the bosonic self-coupling, λ, and the Yukawa coupling between fermion and soliton, g, have a specific relation, g = √(λ/2). As the set of coupled equations of motion of the system is not analytically solvable, we use a numerical method to solve it self-consistently. We obtain the bound energy spectrum, bound states of the system and the corresponding shape of the soliton using a relaxation method, except for the zero mode fermionic state and threshold energies which are analytically solvable. With the aid of these results, we are able to show how the soliton is affected in general and supersymmetric cases. The results we obtain are consistent with the ones in the literature, considering the soliton as background. (orig.)
Selective two-photon excitation of a vibronic state by correlated photons.
Oka, Hisaki
2011-03-28
We theoretically investigate the two-photon excitation of a molecular vibronic state by correlated photons with energy anticorrelation. A Morse oscillator having three sets of vibronic states is used, as an example, to evaluate the selectivity and efficiency of two-photon excitation. We show that a vibrational mode can be selectively excited with high efficiency by the correlated photons, without phase manipulation or pulse-shaping techniques. This can be achieved by controlling the quantum correlation so that the photon pair concurrently has two pulse widths, namely, a temporally narrow width and a spectrally narrow width. Though this concurrence is seemingly contradictory, we can create such a photon pair by tailoring the quantum correlation between two photons.
Coupling modeling and analysis of a wind energy converter
Directory of Open Access Journals (Sweden)
Jie-jie Li
2016-06-01
Full Text Available In this article, the numerical simulation of a 2.0-MW wind energy converter coupling is achieved by three-dimensional computer-aided design modeling technique and finite element method. The static performances and the buckling characteristics of the diaphragm coupling are investigated. The diaphragm coupling is divided into three substructures, namely, torque input end, the middle section, and the torque output end. Considering the assembly and contact conditions, the simulation analysis for stress responses of the diaphragm coupling is carried out. The buckling factor and buckling mode of the diaphragms are obtained, and the geometric parameters of the diaphragms are optimized according to their buckling characteristics. The relationship between the pretightening force of the bolts, which tighten the friction flange and the friction plate, and the sliding torque is given by an empirical formula. The reasonable ranges of the pretightening force and tighten torque of the bolts are recommended. The fatigue analysis of the diaphragms is completed, and the results show that the diaphragms are competent to the designed life of the diaphragm coupling.
Optical vibronic spectra of aggregates in Eu sup 2 sup + -doped KCl and KBr crystals
Pérez, S R; Aceves, R; Rodríguez, R; Barboza, M
2003-01-01
The vibronic structure on the optical absorption, emission, and excitation spectra of aggregates in Eu sup 2 sup + -doped KCl and KBr crystals has been obtained. The crystals were annealed at 435 K. During the aggregation process, four groups of narrow bands were found in KCl: Eu sup 2 sup + and two in KBr: Eu sup 2 sup + ,which were considered as the signature of different Eu sup 2 sup + -ion aggregated phases. The vibration frequency for each group is very similar. (Author)
Nonlinear biodynamics of passengers coupled with quarter car models
Papalukopoulos, C.; Natsiavas, S.
2007-07-01
Biodynamic response of lumped parameter passenger-seat models coupled with simplified models of ground vehicles is investigated. The relatively small dimension of the resulting mechanical models is counterweighted by the complexity introduced by the strongly nonlinear characteristics exhibited by the components of both the biodynamic and the car subsystems. This complexity is enhanced further by the possibility of loss of contact allowed to take place between the wheel and the ground or the passenger and the seat, during strong excitation. After setting up the equations of motion, appropriate methodologies are developed, capturing the dynamic response of the coupled system to transient, harmonic and stochastic excitation, caused by road irregularities. Then, numerical results are presented, illustrating the effect of the excitation amplitude and frequency content on several response quantities related to the dynamic performance of the human and the vehicle components. Special emphasis is put on examining the influence of the seat suspension stiffness and damping characteristics. The results indicate that the nonlinear properties of the coupled model affect significantly its dynamics and can lead to large quantitative and qualitative deviations from the predictions of the corresponding linearized models. Among other things, complex motions are captured, even for harmonic excitation, when the forcing frequency lies between neighboring natural frequencies of the linearized system.
Fully-Coupled Dynamical Jitter Modeling of Momentum Exchange Devices
Alcorn, John
A primary source of spacecraft jitter is due to mass imbalances within momentum exchange devices (MEDs) used for fine pointing, such as reaction wheels (RWs) and variable-speed control moment gyroscopes (VSCMGs). Although these effects are often characterized through experimentation in order to validate pointing stability requirements, it is of interest to include jitter in a computer simulation of the spacecraft in the early stages of spacecraft development. An estimate of jitter amplitude may be found by modeling MED imbalance torques as external disturbance forces and torques on the spacecraft. In this case, MED mass imbalances are lumped into static and dynamic imbalance parameters, allowing jitter force and torque to be simply proportional to wheel speed squared. A physically realistic dynamic model may be obtained by defining mass imbalances in terms of a wheel center of mass location and inertia tensor. The fully-coupled dynamic model allows for momentum and energy validation of the system. This is often critical when modeling additional complex dynamical behavior such as flexible dynamics and fuel slosh. Furthermore, it is necessary to use the fully-coupled model in instances where the relative mass properties of the spacecraft with respect to the RWs cause the simplified jitter model to be inaccurate. This thesis presents a generalized approach to MED imbalance modeling of a rigid spacecraft hub with N RWs or VSCMGs. A discussion is included to convert from manufacturer specifications of RW imbalances to the parameters introduced within each model. Implementations of the fully-coupled RW and VSCMG models derived within this thesis are released open-source as part of the Basilisk astrodynamics software.
A Coupled Simulation Architecture for Agent-Based/Geohydrological Modelling
Jaxa-Rozen, M.
2016-12-01
The quantitative modelling of social-ecological systems can provide useful insights into the interplay between social and environmental processes, and their impact on emergent system dynamics. However, such models should acknowledge the complexity and uncertainty of both of the underlying subsystems. For instance, the agent-based models which are increasingly popular for groundwater management studies can be made more useful by directly accounting for the hydrological processes which drive environmental outcomes. Conversely, conventional environmental models can benefit from an agent-based depiction of the feedbacks and heuristics which influence the decisions of groundwater users. From this perspective, this work describes a Python-based software architecture which couples the popular NetLogo agent-based platform with the MODFLOW/SEAWAT geohydrological modelling environment. This approach enables users to implement agent-based models in NetLogo's user-friendly platform, while benefiting from the full capabilities of MODFLOW/SEAWAT packages or reusing existing geohydrological models. The software architecture is based on the pyNetLogo connector, which provides an interface between the NetLogo agent-based modelling software and the Python programming language. This functionality is then extended and combined with Python's object-oriented features, to design a simulation architecture which couples NetLogo with MODFLOW/SEAWAT through the FloPy library (Bakker et al., 2016). The Python programming language also provides access to a range of external packages which can be used for testing and analysing the coupled models, which is illustrated for an application of Aquifer Thermal Energy Storage (ATES).
Seasonal predictability of Kiremt rainfall in coupled general circulation models
Gleixner, Stephanie; Keenlyside, Noel S.; Demissie, Teferi D.; Counillon, François; Wang, Yiguo; Viste, Ellen
2017-11-01
The Ethiopian economy and population is strongly dependent on rainfall. Operational seasonal predictions for the main rainy season (Kiremt, June–September) are based on statistical approaches with Pacific sea surface temperatures (SST) as the main predictor. Here we analyse dynamical predictions from 11 coupled general circulation models for the Kiremt seasons from 1985–2005 with the forecasts starting from the beginning of May. We find skillful predictions from three of the 11 models, but no model beats a simple linear prediction model based on the predicted Niño3.4 indices. The skill of the individual models for dynamically predicting Kiremt rainfall depends on the strength of the teleconnection between Kiremt rainfall and concurrent Pacific SST in the models. Models that do not simulate this teleconnection fail to capture the observed relationship between Kiremt rainfall and the large-scale Walker circulation.
Coupling of nonlocal and local continuum models by the Arlequinapproach
Han, Fei
2011-08-09
The objective of this work is to develop and apply the Arlequin framework to couple nonlocal and local continuum mechanical models. A mechanically-based model of nonlocal elasticity, which involves both contact and long-range forces, is used for the \\'fine scale\\' description in which nonlocal interactions are considered to have non-negligible effects. Classical continuum mechanics only involving local contact forces is introduced for the rest of the structure where these nonlocal effects can be neglected. Both models overlap in a coupling subdomain called the \\'gluing area\\' in which the total energy is separated into nonlocal and local contributions by complementary weight functions. A weak compatibility is ensured between kinematics of both models using Lagrange multipliers over the gluing area. The discrete formulation of this specific Arlequin coupling framework is derived and fully described. The validity and limits of the technique are demonstrated through two-dimensional numerical applications and results are compared against those of the fully nonlocal elasticity method. © 2011 John Wiley & Sons, Ltd.
A coupled model for intragranular deformation and chemical diffusion
Zhong, Xin; Vrijmoed, Johannes; Moulas, Evangelos; Tajčmanová, Lucie
2017-09-01
A coupled model for chemical diffusion and mechanical deformation is developed in analogy to the studies of poroelasticity and thermoelasticity. Nondimensionalization of the governing equations yields a controlling dimensionless parameter, the Deborah number, given by the ratio of the characteristic time for pressure relaxation and concentration homogenization. Using the Deborah number two types of plausible chemical zonation are distinguished, i.e. diffusion controlled, and mechanically controlled. The transition between these two types of chemical zonation is determined at the conditions where the Deborah number equals one. We apply our model to a chemically zoned plagioclase rim in a spherical coordinate frame assuming homogeneous initial pressure. Using thermodynamic data, an experimentally derived diffusion coefficient and a viscous flow law for plagioclase, our numerical simulations show that up to ∼0.6 GPa grain-scale pressure variation is generated during the diffusion-deformation process. Due to the mechanical-chemical coupling, the pressure variations maintain the chemical zonation longer than predicted by the classical diffusion model. The fully coupled mechanical-chemical model provides an alternative explanation for the preservation of chemically zoned minerals, and may contribute to a better understanding of metamorphic processes in the deep Earth interior.
Coupled surface-water and ground-water model
Swain, Eric D.; Wexler, Eliezer J.
1991-01-01
In areas with dynamic and hydraulically well connected ground-water and surface-water systems, it is desirable that stream-aquifer interaction be simulated with models of equal sophistication and accuracy. Accordingly, a new, coupled ground-water and surface-water model was developed by combining the U.S. Geological Survey models MODFLOW and BRANCH. MODFLOW is the widely used modular three-dimensional, finite-difference, ground-water model and BRANCH is a one-dimensional numerical model commonly used to simulate flow in open-channel networks. Because time steps used in ground-water modeling commonly are much longer than those used in surface-water simulations, provision has been made for handling multiple BRANCH time steps within one MODFLOW time step. Verification testing of the coupled model was done using data from previous studies and by comparing results with output from a simpler four-point implicit open-channel flow model linked with MODFLOW.
Development of a coupled wave-flow-vegetation interaction model
Beudin, Alexis; Kalra, Tarandeep S.; Ganju, Neil K.; Warner, John C.
2017-01-01
Emergent and submerged vegetation can significantly affect coastal hydrodynamics. However, most deterministic numerical models do not take into account their influence on currents, waves, and turbulence. In this paper, we describe the implementation of a wave-flow-vegetation module into a Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system that includes a flow model (ROMS) and a wave model (SWAN), and illustrate various interacting processes using an idealized shallow basin application. The flow model has been modified to include plant posture-dependent three-dimensional drag, in-canopy wave-induced streaming, and production of turbulent kinetic energy and enstrophy to parameterize vertical mixing. The coupling framework has been updated to exchange vegetation-related variables between the flow model and the wave model to account for wave energy dissipation due to vegetation. This study i) demonstrates the validity of the plant posture-dependent drag parameterization against field measurements, ii) shows that the model is capable of reproducing the mean and turbulent flow field in the presence of vegetation as compared to various laboratory experiments, iii) provides insight into the flow-vegetation interaction through an analysis of the terms in the momentum balance, iv) describes the influence of a submerged vegetation patch on tidal currents and waves separately and combined, and v) proposes future directions for research and development.
MOUNTAIN-SCALE COUPLED PROCESSES (TH/THC/THM)MODELS
Energy Technology Data Exchange (ETDEWEB)
Y.S. Wu
2005-08-24
This report documents the development and validation of the mountain-scale thermal-hydrologic (TH), thermal-hydrologic-chemical (THC), and thermal-hydrologic-mechanical (THM) models. These models provide technical support for screening of features, events, and processes (FEPs) related to the effects of coupled TH/THC/THM processes on mountain-scale unsaturated zone (UZ) and saturated zone (SZ) flow at Yucca Mountain, Nevada (BSC 2005 [DIRS 174842], Section 2.1.1.1). The purpose and validation criteria for these models are specified in ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Drift-Scale Abstraction) Model Report Integration'' (BSC 2005 [DIRS 174842]). Model results are used to support exclusion of certain FEPs from the total system performance assessment for the license application (TSPA-LA) model on the basis of low consequence, consistent with the requirements of 10 CFR 63.342 [DIRS 173273]. Outputs from this report are not direct feeds to the TSPA-LA. All the FEPs related to the effects of coupled TH/THC/THM processes on mountain-scale UZ and SZ flow are discussed in Sections 6 and 7 of this report. The mountain-scale coupled TH/THC/THM processes models numerically simulate the impact of nuclear waste heat release on the natural hydrogeological system, including a representation of heat-driven processes occurring in the far field. The mountain-scale TH simulations provide predictions for thermally affected liquid saturation, gas- and liquid-phase fluxes, and water and rock temperature (together called the flow fields). The main focus of the TH model is to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts. The TH model captures mountain-scale three-dimensional flow effects, including lateral diversion and mountain-scale flow patterns. The mountain-scale THC model evaluates TH effects on
Evaluation of Coupled Model Forecasts of Ethiopian Highlands Summer Climate
Directory of Open Access Journals (Sweden)
Mark R. Jury
2014-01-01
Full Text Available This study evaluates seasonal forecasts of rainfall and maximum temperature across the Ethiopian highlands from coupled ensemble models in the period 1981–2006, by comparison with gridded observational products (NMA + GPCC/CRU3. Early season forecasts from the coupled forecast system (CFS are steadier than European community medium range forecast (ECMWF. CFS and ECMWF April forecasts of June–August (JJA rainfall achieve significant fit (r2=0.27, 0.25, resp., but ECMWF forecasts tend to have a narrow range with drought underpredicted. Early season forecasts of JJA maximum temperature are weak in both models; hence ability to predict water resource gains may be better than losses. One aim of seasonal climate forecasting is to ensure that crop yields keep pace with Ethiopia’s growing population. Farmers using prediction technology are better informed to avoid risk in dry years and generate surplus in wet years.
Modelling Nephron Autoregulation and Synchronization in Coupled Nephron Systems
DEFF Research Database (Denmark)
Laugesen, Jakob Lund
between oscillating period-doubling systems is the topic of the larger part of the study. Since synchronization is a fundamental phenomenon in all sciences, it is treated from a general viewpoint by analyzing one of the most simple dynamical systems, the R¨ossler system, both in an externally forced...... feedback process can explain the experimentally observed irregular oscillations in the nephron pressures and flows. The hypothesis is put to test by calculating Lyapunov exponents of a high level mechanism-based model of a nephron and a similar model of two vascular coupled nephrons. Synchronization...... version and in the form of two mutually coupled oscillators. The bifurcational mechanism to resonant dynamics and chaotic phase synchronization is described in detail. The transition from synchronized to non-synchronized dynamics is known to take place at a dense set of saddlenode bifurcations that run...
Multiscale modelling of coupled problems in porous materials
Carmeliet, Jan; Derluyn, Hannelore; Mertens, Stijn; Moonen, Peter
2008-01-01
In this paper a multiscale approach for coupled mechanical and transport phenomena in porous media is presented. It is shown that monoscale approaches show different limitations: phenomena like nonlinear elasticity, hysteresis, stiffness recovery in compressive loading, preferential moisture uptake into cracks, changes of the permeability caused by changes in the pore structure due to chemical processes are not taken adequately into account. The multiscale mechanical model is b...
Coupling a groundwater model with a land surface model to improve water and energy cycle simulation
Directory of Open Access Journals (Sweden)
W. Tian
2012-12-01
Full Text Available Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB is developed based on the full coupling of a typical land surface model (SiB2 and a 3-D variably saturated groundwater model (AquiferFlow. In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reach of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.
A tree-parenchyma coupled model for lung ventilation simulation.
Pozin, Nicolas; Montesantos, Spyridon; Katz, Ira; Pichelin, Marine; Vignon-Clementel, Irene; Grandmont, Céline
2017-11-01
In this article, we develop a lung ventilation model. The parenchyma is described as an elastic homogenized media. It is irrigated by a space-filling dyadic resistive pipe network, which represents the tracheobronchial tree. In this model, the tree and the parenchyma are strongly coupled. The tree induces an extra viscous term in the system constitutive relation, which leads, in the finite element framework, to a full matrix. We consider an efficient algorithm that takes advantage of the tree structure to enable a fast matrix-vector product computation. This framework can be used to model both free and mechanically induced respiration, in health and disease. Patient-specific lung geometries acquired from computed tomography scans are considered. Realistic Dirichlet boundary conditions can be deduced from surface registration on computed tomography images. The model is compared to a more classical exit compartment approach. Results illustrate the coupling between the tree and the parenchyma, at global and regional levels, and how conditions for the purely 0D model can be inferred. Different types of boundary conditions are tested, including a nonlinear Robin model of the surrounding lung structures. Copyright © 2017 John Wiley & Sons, Ltd.
A Coupled Plasma-Sheath Model for High Density Sources
Bose, Deepak; Govindan, T. R.; Meyyappan, M.
2000-01-01
High density, low pressure plasmas are used for etching and deposition in microelectronics fabrication processes. The process characteristics are strongly determined by the ion energy distribution (IED) and the ion flux arriving at the substrate that are responsible for desorption of etch products and neutral dissociation at the surface. The ion flux and energy are determined by a self- consistent modeling of the bulk plasma, where the ions and the neutral radicals are produced, and the sheath, where the ions are accelerated. Due to their widely different time scales, it is a formidable task to self-consistently resolve non-collisional sheath in a high density bulk plasma model. In this work, we first describe a coupled plasma-sheath model that attempts to resolve the non-collisional sheath in a reactor scale model. Second, we propose a semianalytical radio frequency (RF) sheath model to improve ion dynamics.
Gauge coupling unification in a classically scale invariant model
Energy Technology Data Exchange (ETDEWEB)
Haba, Naoyuki; Ishida, Hiroyuki [Graduate School of Science and Engineering, Shimane University,Matsue 690-8504 (Japan); Takahashi, Ryo [Graduate School of Science, Tohoku University,Sendai, 980-8578 (Japan); Yamaguchi, Yuya [Graduate School of Science and Engineering, Shimane University,Matsue 690-8504 (Japan); Department of Physics, Faculty of Science, Hokkaido University,Sapporo 060-0810 (Japan)
2016-02-08
There are a lot of works within a class of classically scale invariant model, which is motivated by solving the gauge hierarchy problem. In this context, the Higgs mass vanishes at the UV scale due to the classically scale invariance, and is generated via the Coleman-Weinberg mechanism. Since the mass generation should occur not so far from the electroweak scale, we extend the standard model only around the TeV scale. We construct a model which can achieve the gauge coupling unification at the UV scale. In the same way, the model can realize the vacuum stability, smallness of active neutrino masses, baryon asymmetry of the universe, and dark matter relic abundance. The model predicts the existence vector-like fermions charged under SU(3){sub C} with masses lower than 1 TeV, and the SM singlet Majorana dark matter with mass lower than 2.6 TeV.
A Fully Coupled Computational Model of the Silylation Process
Energy Technology Data Exchange (ETDEWEB)
G. H. Evans; R. S. Larson; V. C. Prantil; W. S. Winters
1999-02-01
This report documents the development of a new finite element model of the positive tone silylation process. Model development makes use of pre-existing Sandia technology used to describe coupled thermal-mechanical behavior in deforming metals. Material properties and constitutive models were obtained from the literature. The model is two-dimensional and transient and focuses on the part of the lithography process in which crosslinked and uncrosslinked resist is exposed to a gaseous silylation agent. The model accounts for the combined effects of mass transport (diffusion of silylation agent and reaction product), chemical reaction resulting in the uptake of silicon and material swelling, the generation of stresses, and the resulting material motion. The influence of stress on diffusion and reaction rates is also included.
A 3D fully coupled wave-current-sediment model
Liu, L.; Shen, L.; Feddy, A.; Bennis, A. C.; Mouazé, D.; Chareyre, B.
2016-02-01
In the framework of new energy sources, marine energy can contribute to diversification of energy mix. The study site is the Alderney Race where tidal velocities can exceed 4 meters per second. With this high current speeds, this site represents one of the best opportunities for exploitation of the tidal stream. Our aim is to investigate the influence of this high current speeds on the sediment transport. Modeling the sediment transport in the coastal environment requires an accurate prediction of current velocity and bottom shear stress. For that, the numerical wave-current model MARS-WW3 will be used to analyze the wave-current interaction and comparisons with experimental ADCP data will be presented. To simulate the non-cohesive sediment transport (such as sand, gravel or pebbles), this numerical model will be coupled with a discrete element model like YADE. In first time, the discrete model used will be validated with different tests cases. After, we will present the coupling MARS-WW3-YADE, in particular the expression and exchange of different forces exerted by the fluid flow on the sediments and by sediments on the fluid. Finally, simulations of the sediment transport will be shown and we will interest in particular to the influence of size and density of sediments. We also investigate the effects of tide and wave currents on the sediment displacement.
Safer Batteries through Coupled Multiscale Modeling (ICCS 2015)
Energy Technology Data Exchange (ETDEWEB)
Turner, John A [ORNL; Allu, Srikanth [ORNL; Berrill, Mark A [ORNL; Elwasif, Wael R [ORNL; Kalnaus, Sergiy [ORNL; Kumar, Abhishek [ORNL; Lebrun-Grandie, Damien T [ORNL; Pannala, Dr. Sreekanth [Saudi Basic Industries Coropration (SABIC); Simunovic, Srdjan [ORNL
2015-01-01
Batteries are highly complex electrochemical systems, with performance and safety governed by coupled nonlinear electrochemical-electrical-thermal-mechanical processes over a range of spatiotemporal scales. We describe a new, open source computational environment for battery simulation known as VIBE - the Virtual Integrated Battery Environment. VIBE includes homogenized and pseudo-2D electrochemistry models such as those by Newman-Tiedemann-Gu (NTG) and Doyle- Fuller-Newman (DFN, a.k.a. DualFoil) as well as a new advanced capability known as AMPERES (Advanced MultiPhysics for Electrochemical and Renewable Energy Storage). AMPERES provides a 3D model for electrochemistry and full coupling with 3D electrical and thermal models on the same grid. VIBE/AMPERES has been used to create three-dimensional battery cell and pack models that explicitly simulate all the battery components (current collectors, electrodes, and separator). The models are used to predict battery performance under normal operations and to study thermal and mechanical response under adverse conditions.
Coupling patterns in heterotic calabi-Yau models
Gray, James
2017-11-01
We describe the structure of relationships between, and vanishings of, couplings that can occur at high energies in smooth compactifications of the heterotic string. We begin with an explanation of the well known fact that the standard Yukawa unification seen in four dimensional Grand Unified Theories does not generically occur in these models, despite the presence of an underlying Grand Unified group. We then describe an example that shows that in special situations (partial) Yukawa unification can be restored. In constructing this example, we will see an illustration of another way in which heterotic compactifications can lead to special structure in superpotential couplings. This presentation was based on work with a number of different collaborators to whom I am immensely grateful [1, 2, 3, 4, 5].
Improved modelling of atmospheric ammonia over Denmark using the coupled modelling system DAMOS
DEFF Research Database (Denmark)
Geels, Camilla; Andersen, Helle Vibeke; Skjøth, Carsten Ambelas
2012-01-01
A local-scale Gaussian dispersion-deposition model (OML-DEP) has been coupled to a regional chemistry-transport model (DEHM with a resolution of approximately 6 km x 6 km over Denmark) in the Danish Ammonia Modelling System, DAMOS. Thereby, it has been possible to model the distribution of ammonia...... the period 2005-2009. A standard time series analysis (using statistic parameters like correlation and bias) shows that the coupled model system captures the measured time series better than the regional- scale model alone. However, our study also shows that about 50% of the modelled concentration level...
Coupled Model Simulation of Snowfall Events Over the Black Hills
Wang, Jianzhong; Hjelmfelt, M. R.; Capehart, W. J.
2000-01-01
Although many long-term simulations of snow accumulation and oblation have been made using stand-alone land surface models and surface models coupled with GCMs, less research has focused on short-term event simulations. Actually, accurate event simulations of snow-related processes are the basis for successful long-term simulation. Three advantages of event simulations of snowfall and snow melting are availability of: (1) intensive observation data from field experiments for validation; (2) more physically-realistic precipitation schemes for use in atmospheric models to simulate snowfall; and (3) a more detailed analysis of the snow melting processes. In addition to the complexities of snow related processes themselves, terrain-induced effects on snowfall/snow melting make simulations of snow events more difficult. Climatological observations indicate that terrain features such as the Black Hills of South Dakota and Wyoming can exert important effects on snow accumulation and snow oblation processes. One of the primary effects is that the orography causes forced uplift of airflow and causes atmospheric waves to form both upwind and downwind of it. Airflow often splits around the obstacle, converging on the lee side. This convergence may lead to precipitation enhancement. It also provides an elevated heat and moisture source that enhances atmospheric instability. During the period of April 5-May 5, 1999, the Upper Missouri River Basin Pilot Project (UMRBPP) made intensive observations on precipitation events occurring in the Black Hills. Two moderate snowfall events were captured during the period. The resulting high temporal and spatial resolution data provides opportunities to investigate terrain effects on snowfall amount, distribution, and melting. Successful simulation of snowfall amount, distribution, and evolution using atmospheric models is important to subsequent modeling of snow melting using snow sub-models in land surface schemes. In this paper, a
Decadal climate variability simulated in a coupled general circulation model
Energy Technology Data Exchange (ETDEWEB)
Walland, D.J. [Bureau of Meteorology, Melbourne, VIC (Australia). National Climate Centre; Power, S.B. [Bureau of Meteorology, Melbourne, VIC (Australia). Research Centre; Hirst, A.C. [Commonwealth Scientific Industrial Research Organisation Division of Atmospheric Research (Australia)
2000-02-01
A 1000 year integration of the CSIRO coupled ocean-atmosphere general circulation model is used to study low frequency (decadal to centennial) climate variability in precipitation and temperature. The model is shown to exhibit sizeable decadal variability for these fields, generally accounting for approximately 20 to 40% of the variability (greater than one year) in precipitation and up to 80% for temperature. An empirical orthogonal function (EOF) analysis is applied to the model output to show some of the major statistical modes of low frequency variability. The first EOF spatial pattern looks very much like that of the interannual ENSO pattern. It bears considerable resemblance to observational estimates and is centred in the Pacific extending into both hemispheres. It modulates both precipitation and temperature globally. The EOF has a time evolution that appears to be more than just red noise. Finally, the link between SST in the Pacific with Australian rainfall variability seen in observations is also evident in the model. (orig.)
Coupling atmospheric and ocean wave models for storm simulation
DEFF Research Database (Denmark)
Du, Jianting
This thesis studies the wind-wave interactions through the coupling between the atmospheric model and ocean surface wave models. Special attention is put on storm simulations in the North Sea for wind energy applications in the coastal zones. The two aspects, namely storm conditions and coastal...... and coastal conditions, z0 parameterization method often fails in reproducing z0 because the complexity of the sea state cannot be represented by a few selected wave parameters. Different from the parameterization method, physics-based methods take the idea that the loss of momentum and kinetic energy from...... the above mentioned challenges, a wave boundary layer model (WBLM) is implemented in the wave model SWAN as a new Sin. The WBLM Sin is based on the momentum and kinetic energy conservation. The wave-induced mean wind profile changes at all vertical levels within the wave boundary layer, and the spectral...
Magnetic Coupled Circuits Modeling of Induction Machines Oriented to Diagnostics
Directory of Open Access Journals (Sweden)
Tarek AROUI
2008-12-01
Full Text Available In this paper, a transient model of the faulty machine is developed. The model is referred to a three phase stator winding, while the rotor has been represented by all the meshes allowing for the representation of various faults. The model is based on coupled magnetic circuit theory by considering that the current in each bar is an independent variable. The model incorporates non-sinusoidal air-gap magneto motive force (MMF produced by both stator and rotor, therefore it will include all the space harmonics in the machine. Simulations and experimental results were then used to study rotor faults cause-effect relationships in the stator current and the frequency signature.
Solutions of several coupled discrete models in terms of Lamé ...
Indian Academy of Sciences (India)
. We provide an extensive set of exact quasiperiodic solutions of a number of coupled discrete models in terms of Lamé polynomials of arbitrary order. The models discussed are: (i) coupled Salerno model, (ii) coupled Ablowitz–Ladik model, ...
The Madden-Julian Oscillation in NCEP Coupled Model Simulation
Directory of Open Access Journals (Sweden)
Wanqiu Wang Kyong-Hwan Seo
2009-01-01
Full Text Available This study documents a detailed analysis on the Madden-Julian Oscillation (MJO simulated by the National Centers for Environmental Prediction (NCEP using the Global Forecast System (GFS model version 2003 coupled with the Climate Forecast System model (CFS consisting of the 2003 version of GFS and the Geophysical Fluid Dynamics Laboratory (GFDL Modular Ocean Model V.3 (MOM3. The analyses are based upon a 21-year simulation of AMIP-type with GFS and CMIP-type with CFS. It is found that air-sea coupling in CFS is shown to improve the coherence between convection and large-scale circulation associated with the MJO. The too fast propagation of convection from the Indian Ocean to the maritime continents and the western Pacific in GFS is improved (slowed down in CFS. Both GFS and CFS produce too strong intraseasonal convective heating and circulation anomalies in the central-eastern Pacific; further, the air-sea coupling in CFS enhances this unrealistic feature. The simulated mean slow phase speed of east ward propagating low-wavenumber components shown in the wavenumber-frequency spectra is due to the slow propagation in the central-eastern Pacific in both GFS and CFS. Errors in model climatology may have some effect upon the simulated MJO and two possible influences are: (i CFS fails to simulate the westerlies over maritime continents and western Pacific areas, resulting in an unrealistic representation of surface latent heat flux associated with the MJO; and (ii vertical easterly wind shear from the Indian Ocean to the western Pacific in CFS is much weaker than that in the observation and in GFS, which may adversely affect the eastward propagation of the simulated MJO.
WRF-Fire: coupled weather-wildland fire modeling with the weather research and forecasting model
Janice L. Coen; Marques Cameron; John Michalakes; Edward G. Patton; Philip J. Riggan; Kara M. Yedinak
2012-01-01
A wildland fire behavior module (WRF-Fire) was integrated into the Weather Research and Forecasting (WRF) public domain numerical weather prediction model. The fire module is a surface fire behavior model that is two-way coupled with the atmospheric model. Near-surface winds from the atmospheric model are interpolated to a finer fire grid and used, with fuel properties...
Dillon, Joseph; Yarkony, David R; Schuurman, Michael S
2011-01-28
The quadratic vibronic coupling model is an important computational tool for simulating photoelectron spectra involving strongly coupled electronic states in polyatomic molecules. However, recent work has indicated the need for higher order terms, with most of the initial studies focusing on molecules with symmetry-required degeneracies. In this study we report an extension of our approach for constructing fully quadratic representations of bound electronic states coupled by conical intersections, which allows for the inclusion of higher order terms, demonstrated here employing a quartic expansion. Procedures are developed that eliminate unphysical behavior for large displacements, a problem likely to be an endemic to anharmonic expansions. Following work on representing dissociative electronic states, Lagrange multipliers are used to constrain the constructed representation to reproduce exactly the energy, energy gradients, and∕or derivative couplings at specific points, or nodes, in nuclear coordinate space. The approach is illustrated and systematically studied using the four lowest electronic states of triazolyl, (CH)(2)N(3).
Optimizing phonon space in the phonon-coupling model
Tselyaev, V.; Lyutorovich, N.; Speth, J.; Reinhard, P.-G.
2017-08-01
We present a new scheme to select the most relevant phonons in the phonon-coupling model, named here the time-blocking approximation (TBA). The new criterion, based on the phonon-nucleon coupling strengths rather than on B (E L ) values, is more selective and thus produces much smaller phonon spaces in the TBA. This is beneficial in two respects: first, it curbs the computational cost, and second, it reduces the danger of double counting in the expansion basis of the TBA. We use here the TBA in a form where the coupling strength is regularized to keep the given Hartree-Fock ground state stable. The scheme is implemented in a random-phase approximation and TBA code based on the Skyrme energy functional. We first explore carefully the cutoff dependence with the new criterion and can work out a natural (optimal) cutoff parameter. Then we use the freshly developed and tested scheme for a survey of giant resonances and low-lying collective states in six doubly magic nuclei looking also at the dependence of the results when varying the Skyrme parametrization.
Extended Neural Metastability in an Embodied Model of Sensorimotor Coupling
Aguilera, Miguel; Bedia, Manuel G.; Barandiaran, Xabier E.
2016-01-01
The hypothesis that brain organization is based on mechanisms of metastable synchronization in neural assemblies has been popularized during the last decades of neuroscientific research. Nevertheless, the role of body and environment for understanding the functioning of metastable assemblies is frequently dismissed. The main goal of this paper is to investigate the contribution of sensorimotor coupling to neural and behavioral metastability using a minimal computational model of plastic neural ensembles embedded in a robotic agent in a behavioral preference task. Our hypothesis is that, under some conditions, the metastability of the system is not restricted to the brain but extends to the system composed by the interaction of brain, body and environment. We test this idea, comparing an agent in continuous interaction with its environment in a task demanding behavioral flexibility with an equivalent model from the point of view of “internalist neuroscience.” A statistical characterization of our model and tools from information theory allow us to show how (1) the bidirectional coupling between agent and environment brings the system closer to a regime of criticality and triggers the emergence of additional metastable states which are not found in the brain in isolation but extended to the whole system of sensorimotor interaction, (2) the synaptic plasticity of the agent is fundamental to sustain open structures in the neural controller of the agent flexibly engaging and disengaging different behavioral patterns that sustain sensorimotor metastable states, and (3) these extended metastable states emerge when the agent generates an asymmetrical circular loop of causal interaction with its environment, in which the agent responds to variability of the environment at fast timescales while acting over the environment at slow timescales, suggesting the constitution of the agent as an autonomous entity actively modulating its sensorimotor coupling with the world. We
Coupling capacitor voltage transformer: A model for electromagnetic transient studies
Energy Technology Data Exchange (ETDEWEB)
Fernandes, D.; Neves, W.L.A. [Department of Electrical Engineering, Federal University of Campina Grande, Av. Aprigio Veloso, 882 Bodocongo, 58.109-970 Campina Grande, PB (Brazil); Vasconcelos, J.C.A. [Companhia Hidro Eletrica do Sao Francisco, Rua Delmiro Gouveia, 333 Bongi, 50.761-901 Recife, PE (Brazil)
2007-02-15
In this work, an accurate coupling capacitor voltage transformer (CCVT) model for electromagnetic transient studies is presented. The model takes into account linear and nonlinear elements. A support routine was developed to compute the linear 230kV CCVT parameters (resistances, inductances and capacitances) from frequency response data. The magnetic core and surge arrester nonlinear characteristics were estimated from laboratory measurements as well. The model is used in connection with the electromagnetic transients program (EMTP) to predict the CCVT performance when it is submitted to transient overvoltages, as are the cases of voltages due to the ferroresonance phenomenon and circuit breaker switching. The difference between simulated and measured results is fairly small. Simulations had shown that transient overvoltages produced inside the CCVT, when a short circuit is cleared at the CCVT secondary side, are effectively damped out by the ferroresonance suppression circuit and the protection circuit. (author)
One-loop Yukawa couplings in local models
Energy Technology Data Exchange (ETDEWEB)
Conlon, Joseph P. [Rudolf Peierls Center for Theoretical Physics, Oxford (United Kingdom); Balliol College, Oxford (United Kingdom); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Palti, Eran [Centre de Physique Theorique, Ecole Polytechnique, CNRS, Palaiseau (France)
2010-07-15
We calculate the one-loop Yukawa couplings and threshold corrections for supersymmetric local models of branes at singularities in type IIB string theory. We compute the corrections coming both from wavefunction and vertex renormalisation. The former comes in the IR from conventional field theory running and in the UV from threshold corrections that cause it to run from the winding scale associated to the full Calabi-Yau volume. The vertex correction is naively absent as it appears to correspond to superpotential renormalisation. However, we find that while the Wilsonian superpotential is not renormalised there is a physical vertex correction in the 1PI action associated to light particle loops. (orig.)
Large time periodic solutions to coupled chemotaxis-fluid models
Jin, Chunhua
2017-12-01
In this paper, we deal with the time periodic problem to coupled chemotaxis-fluid models. We prove the existence of large time periodic strong solutions for the full chemotaxis-Navier-Stokes system in spatial dimension N=2, and the existence of large time periodic strong solutions for the chemotaxis-Stokes system in spatial dimension N=3. On the basis of these, the regularity of the solutions can be further improved. More precisely speaking, if the time periodic source g and the potential force \
A coupled chemotaxis-fluid model: Global existence
Liu, Jian-Guo
2011-09-01
We consider a model arising from biology, consisting of chemotaxis equations coupled to viscous incompressible fluid equations through transport and external forcing. Global existence of solutions to the Cauchy problem is investigated under certain conditions. Precisely, for the chemotaxis-Navier- Stokes system in two space dimensions, we obtain global existence for large data. In three space dimensions, we prove global existence of weak solutions for the chemotaxis-Stokes system with nonlinear diffusion for the cell density.© 2011 Elsevier Masson SAS. All rights reserved.
Noise controlled synchronization in potassium coupled neural models
DEFF Research Database (Denmark)
Postnov, Dmitry E; Ryazanova, Ludmila S; Zhirin, Roman A
2007-01-01
The paper applies biologically plausible models to investigate how noise input to small ensembles of neurons, coupled via the extracellular potassium concentration, can influence their firing patterns. Using the noise intensity and the volume of the extracellular space as control parameters, we...... show that potassium induced depolarization underlies the formation of noise-induced patterns such as delayed firing and synchronization. These phenomena are associated with the appearance of new time scales in the distribution of interspike intervals that may be significant for the spatio...
One-loop Yukawa Couplings in Local Models
Conlon, Joseph P; Palti, Eran; 10.1007
2010-01-01
We calculate the one-loop Yukawa couplings and threshold corrections for supersymmetric local models of branes at singularities in type IIB string theory. We compute the corrections coming both from wavefunction and vertex renormalisation. The former comes in the IR from conventional field theory running and in the UV from threshold corrections that cause it to run from the winding scale associated to the full Calabi-Yau volume. The vertex correction is naively absent as it appears to correspond to superpotential renormalisation. However, we find that while the Wilsonian superpotential is not renormalised there is a physical vertex correction in the 1PI action associated to light particle loops.
A 2D climate energy balance model coupled with a 3D deep ocean model
Directory of Open Access Journals (Sweden)
J. Ildefonso Diaz
2007-05-01
Full Text Available We study a three dimensional climate model which represents the coupling of the mean surface temperature with the ocean temperature. We prove the existence of a bounded weak solution by a fixed point argument.
Remote sensing data assimilation using coupled radiative transfer models
Verhoef, Wout; Bach, Heike
This paper discusses data assimilation of biophysical parameters retrieved from optical remote sensing images in land surface process models by means of image simulation and model inversion. Two different approaches are presented. The first is based on model inversion of atmospherically corrected Landsat TM surface reflectance images and assimilation of the retrieved parameters in a crop growth model. In the second approach top-of-atmosphere (TOA) hyperspectral radiance images have been simulated for the future ESA mission SPECTRA. In this case only the simulation of the images has been executed in order to demonstrate the feasibility of this task with existing software running on a PC. The radiative transfer models that have been used are PROSPECT (leaf level), GeoSAIL (canopy level) and MODTRAN4 (atmosphere). Coupling of this chain of models to land use information of the area can be used to generate TOA radiance images. Comparison of simulated images with actual remote sensing data can be applied to retrieve biophysical parameters and in turn these can be employed to update process models of crop growth.
Coupled spin models for magnetic variation of planets and stars
Nakamichi, A.; Mouri, H.; Schmitt, D.; Ferriz-Mas, A.; Wicht, J.; Morikawa, M.
2012-07-01
Geomagnetism is characterized by intermittent polarity reversals and rapid fluctuations. We have recently proposed a coupled macro-spin model to describe these dynamics based on the idea that the whole dynamo mechanism is described by the coherent interactions of many local elements. In this paper, we further develop this idea and construct the minimal model for magnetic variations. This simple model naturally yields many of the observed features of geomagnetism: its time evolution, the power spectrum, the frequency distribution of stable polarity periods etc. This model is characterized by two coexisting phases of spins: i.e. the cluster phase which determines the global dipole magnetic moment, and the expanded phase which gives random perpetual perturbations that yield the intermittent polarity flip of the dipole moment. This model can also describe the synchronization of the spin oscillations. This corresponds to the case of our Sun and the model well describes the quasi-regular cycles of the solar magnetism. Furthermore, by analysing the relevant terms of magnetohydrodynamic equations based on our model, we have obtained a scaling relation for the magnetism for planets, satellites and the Sun. Comparing it with various observations, we can estimate the relevant scale of the macro-spins.
Modelling floor heating systems using a validated two-dimensional ground coupled numerical model
DEFF Research Database (Denmark)
Weitzmann, Peter; Kragh, Jesper; Roots, Peter
2005-01-01
and foundation on the performance of the floor heating sys-tem. The ground coupled floor heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simu-lation model with inclusion of heat losses and heat supply to the room above...... the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is impor-tant to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further...
Coupled hydrologic and hydraulic modeling of Upper Niger River Basin
Fleischmann, Ayan; Siqueira, Vinícius; Paris, Adrien; Collischonn, Walter; Paiva, Rodrigo; Gossett, Marielle; Pontes, Paulo; Calmant, Stephane; Biancamaria, Sylvain; Crétaux, Jean-François; Tanimoune, Bachir
2017-04-01
The Upper Niger Basin is located in Western Africa, flowing from Guinea Highlands towards the Sahel region. In this area lies the seasonally inundated Niger Inland Delta, which supports important environmental services such as habitats for wildlife, climate and flood regulation, as well as large fishery and agricultural areas. In this study, we present the application of MGB-IPH large scale hydrologic and hydrodynamic model for the Upper Niger Basin, totaling c.a. 650,000 km2 and set up until the city of Niamey in Niger. The model couples hydrological vertical balance and runoff generation with hydrodynamic flood wave propagation, by allowing infiltration from floodplains into soil column as well as representing backwater effects and floodplain storage throughout flat areas such as the Inland Delta. The model is forced with TRMM 3B42 daily precipitation and Climate Research Unit (CRU) climatology for the period 2000-2010, and was calibrated against in-situ discharge gauges and validated with in-situ water level, remotely sensed estimations of flooded areas (classification of MODIS imagery) and satellite altimetry (JASON-2 mission). Model results show good predictions for calibrated daily discharge and validated water level and altimetry at stations both upstream and downstream of the delta (Nash-Sutcliffe Efficiency>0.7 for all stations), as well as for flooded areas within the delta region (ENS=0.5; r2=0.8), allowing a good representation of flooding dynamics basinwide and simulation of flooding behavior of both perennial (e.g., Niger main stem) and ephemeral rivers (e.g., Niger Red Flood tributaries in Sahel). Coupling between hydrology and hydrodynamic processes indicates an important feedback between floodplain and soil water storage that allows high evapotranspiration rates even after the flood passage around the inner delta area. Also, representation of water retention in floodplain channels and distributaries in the inner delta (e.g., Diaka river
Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal
Energy Technology Data Exchange (ETDEWEB)
Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens
2010-08-31
example, the excavation-damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability (Tsang et al., 2005). Because of clay's swelling and shrinkage behavior (depending on whether the clay is in imbibition or drainage processes), fracture properties in the EDZ are quite dynamic and evolve over time as hydromechanical conditions change. To understand and model the coupled processes and their impact on repository performance is critical for the defensible performance assessment of a clay repository. Within the Natural Barrier System (NBS) group of the Used Fuel Disposition (UFD) Campaign at DOE's Office of Nuclear Energy, LBNL's research activities have focused on understanding and modeling such coupled processes. LBNL provided a report in this April on literature survey of studies on coupled processes in clay repositories and identification of technical issues and knowledge gaps (Tsang et al., 2010). This report will document other LBNL research activities within the natural system work package, including the development of constitutive relationships for elastic deformation of clay rock (Section 2), a THM modeling study (Section 3) and a THC modeling study (Section 4). The purpose of the THM and THC modeling studies is to demonstrate the current modeling capabilities in dealing with coupled processes in a potential clay repository. In Section 5, we discuss potential future R&D work based on the identified knowledge gaps. The linkage between these activities and related FEPs is presented in Section 6.
Directory of Open Access Journals (Sweden)
R. Barthel
2006-01-01
Full Text Available Model coupling requires a thorough conceptualisation of the coupling strategy, including an exact definition of the individual model domains, the "transboundary" processes and the exchange parameters. It is shown here that in the case of coupling groundwater flow and hydrological models – in particular on the regional scale – it is very important to find a common definition and scale-appropriate process description of groundwater recharge and baseflow (or "groundwater runoff/discharge" in order to achieve a meaningful representation of the processes that link the unsaturated and saturated zones and the river network. As such, integration by means of coupling established disciplinary models is problematic given that in such models, processes are defined from a purpose-oriented, disciplinary perspective and are therefore not necessarily consistent with definitions of the same process in the model concepts of other disciplines. This article contains a general introduction to the requirements and challenges of model coupling in Integrated Water Resources Management including a definition of the most relevant technical terms, a short description of the commonly used approach of model coupling and finally a detailed consideration of the role of groundwater recharge and baseflow in coupling groundwater models with hydrological models. The conclusions summarize the most relevant problems rather than giving practical solutions. This paper aims to point out that working on a large scale in an integrated context requires rethinking traditional disciplinary workflows and encouraging communication between the different disciplines involved. It is worth noting that the aspects discussed here are mainly viewed from a groundwater perspective, which reflects the author's background.
Modeling of price and profit in coupled-ring networks
Tangmongkollert, Kittiwat; Suwanna, Sujin
2016-06-01
We study the behaviors of magnetization, price, and profit profiles in ring networks in the presence of the external magnetic field. The Ising model is used to determine the state of each node, which is mapped to the buy-or-sell state in a financial market, where +1 is identified as the buying state, and -1 as the selling state. Price and profit mechanisms are modeled based on the assumption that price should increase if demand is larger than supply, and it should decrease otherwise. We find that the magnetization can be induced between two rings via coupling links, where the induced magnetization strength depends on the number of the coupling links. Consequently, the price behaves linearly with time, where its rate of change depends on the magnetization. The profit grows like a quadratic polynomial with coefficients dependent on the magnetization. If two rings have opposite direction of net spins, the price flows in the direction of the majority spins, and the network with the minority spins gets a loss in profit.
Modelling blast induced damage from a fully coupled explosive charge
Onederra, Italo A.; Furtney, Jason K.; Sellers, Ewan; Iverson, Stephen
2015-01-01
This paper presents one of the latest developments in the blasting engineering modelling field—the Hybrid Stress Blasting Model (HSBM). HSBM includes a rock breakage engine to model detonation, wave propagation, rock fragmentation, and muck pile formation. Results from two controlled blasting experiments were used to evaluate the code’s ability to predict the extent of damage. Results indicate that the code is capable of adequately predicting both the extent and shape of the damage zone associated with the influence of point-of-initiation and free-face boundary conditions. Radial fractures extending towards a free face are apparent in the modelling output and matched those mapped after the experiment. In the stage 2 validation experiment, the maximum extent of visible damage was of the order of 1.45 m for the fully coupled 38-mm emulsion charge. Peak radial velocities were predicted within a relative difference of only 1.59% at the nearest history point at 0.3 m from the explosive charge. Discrepancies were larger further away from the charge, with relative differences of −22.4% and −42.9% at distances of 0.46 m and 0.61 m, respectively, meaning that the model overestimated particle velocities at these distances. This attenuation deficiency in the modelling produced an overestimation of the damage zone at the corner of the block due to excessive stress reflections. The extent of visible damage in the immediate vicinity of the blasthole adequately matched the measurements. PMID:26412978
A coupled energy transport and hydrological model for urban canopies
Wang, Z.; Bou-Zeid, E.; Smith, J. A.
2011-12-01
Urban land-atmosphere interaction has been attracting more research efforts in order to understand the complex physics of flow and mass and heat transport in urban surfaces and the lower urban atmosphere. In this work, we developed and implemented a new physically-based single-layer urban canopy model, coupling the surface exchange of energy and the subsurface transport of water/soil moisture. The new model incorporates sub-facet heterogeneity for each urban surface (roof, wall or ground). This better simulates the energy transport in urban canopy layers, especially over low-intensity built (suburban type) terrains that include a significant fraction of vegetated surfaces. We implemented detailed urban hydrological models for both natural terrains (bare soil and vegetation) and porous engineered materials with water-holding capacity (concrete, gravel, etc). The skill of the new scheme was tested against experimental data collected through a wireless sensor network deployed over the campus of Princeton University. The model performance was found to be robust and insensitive to changes in weather conditions or seasonal variability. Predictions of the volumetric soil water content were also in good agreement with field measurements, highlighting the model capability of capturing subsurface water transport for urban lawns. The new model was also applied to a case study assessing different strategies, i.e. white versus green roofs, in the mitigation of urban heat island effect.
A coupled vegetation/sediment transport model for dryland environments
Mayaud, Jerome R.; Bailey, Richard M.; Wiggs, Giles F. S.
2017-04-01
Dryland regions are characterized by patchy vegetation, erodible surfaces, and erosive aeolian processes. Understanding how these constituent factors interact and shape landscape evolution is critical for managing potential environmental and anthropogenic impacts in drylands. However, modeling wind erosion on partially vegetated surfaces is a complex problem that has remained challenging for researchers. We present the new, coupled cellular automaton Vegetation and Sediment TrAnsport (ViSTA) model, which is designed to address fundamental questions about the development of arid and semiarid landscapes in a spatially explicit way. The technical aspects of the ViSTA model are described, including a new method for directly imposing oblique wind and transport directions onto a cell-based domain. Verification tests for the model are reported, including stable state solutions, the impact of drought and fire stress, wake flow dynamics, temporal scaling issues, and the impact of feedbacks between sediment movement and vegetation growth on landscape morphology. The model is then used to simulate an equilibrium nebkha dune field, and the resultant bed forms are shown to have very similar size and spacing characteristics to nebkhas observed in the Skeleton Coast, Namibia. The ViSTA model is a versatile geomorphological tool that could be used to predict threshold-related transitions in a range of dryland ecogeomorphic systems.
Modeling crop water productivity using a coupled SWAT-MODSIM model
This study examines the water productivity of irrigated wheat and maize yields in Karkheh River Basin (KRB) in the semi-arid region of Iran using a coupled modeling approach consisting of the hydrological model (SWAT) and the river basin water allocation model (MODSIM). Dynamic irrigation requireme...
Modeling and simulation of coupled ethanol and biogas production
Energy Technology Data Exchange (ETDEWEB)
Schausberger, Paul; Boesch, Peter; Friedl, Anton [Vienna University of Technology, Vienna (Austria)
2010-04-15
Ethanol produced from renewable resources is widely regarded as an option to substitute traditional fossil fuels. By coupling the ethanol production to biogas production, an energy autarkic process with minimum ecological footprint can be created. Capable engineering tools are needed to design such processes due to their complexity and the integration necessary. Here, we present a modeling strategy that can serve this task as it allows the steady-state flowsheet simulation of biotechnological production of alternative fuels from renewable resources. The modeling concept is explained and applied to a small-scale self-sustaining ethanol production (1,000 t/a fuel-grade ethanol). An adjunct pinch-analysis for heat integration further demonstrates the potential of the tool developed for the investigation and design of future production of fuel and chemical raw materials. (orig.)
A global hybrid coupled model based on Atmosphere-SST feedbacks
Cimatoribus, Andrea A; Dijkstra, Henk A
2011-01-01
A global hybrid coupled model is developed, with the aim of studying the effects of ocean-atmosphere feedbacks on the stability of the Atlantic meridional overturning circulation. The model includes a global ocean general circulation model and a statistical atmosphere model. The statistical atmosphere model is based on linear regressions of data from a fully coupled climate model on sea surface temperature both locally and hemispherically averaged, being the footprint of Atlantic meridional overturning variability. It provides dynamic boundary conditions to the ocean model for heat, freshwater and wind-stress. A basic but consistent representation of ocean-atmosphere feedbacks is captured in the hybrid coupled model and it is more than ten times faster than the fully coupled climate model. The hybrid coupled model reaches a steady state with a climate close to the one of the fully coupled climate model, and the two models also have a similar response (collapse) of the Atlantic meridional overturning circulati...
Representing Icebergs In A Fully Coupled Climate Model
Bügelmayer, Marianne; Roche, Didier; Renssen, Hans
2014-05-01
Changes in the global climate during past and current times strongly impact the Polar Regions, which in turn affect the global climate due to several mechanisms, such as albedo, topography, ablation and ice discharge. Icebergs are an important part of the climate system as they interact with the ocean, atmosphere and cryosphere. Several approaches have been taken to incorporate iceberg calving into numerical models under different climate forcings. The studies done so far have in common that the icebergs were moved by reconstructed or modelled forcing fields and that the initial size distribution of the icebergs was prescribed according to present day observations. Hence, uncertainties in the forcing fields and in the parameterization of the iceberg size may alter the results. To investigate the impact of the background forcing (atmosphere, ocean) and the pre-defined size distribution on the icebergs and consequently on the Northern hemisphere climate and the Greenland ice sheet, we have coupled an earth system model of intermediate complexity (iLOVECLIM, Roche et al., 2013) to an ice sheet/ice shelf model (GRISLI, Ritz et al., 2001) and an iceberg module (Jongma et al., 2009; Bügelmayer et al., 2014). Using this set-up, we performed 15 sensitivity experiments that differ in the applied forcing (atmosphere, ocean), the applied boundary conditions (pre-industrial, 4xCO2, 1/4 x CO2) and the initial size distribution of the icebergs. In the presented study only the Greenland ice sheet is considered. We find that, under pre-industrial conditions, the atmospheric forcing pushes the icebergs further away from their calving sites and further into the North Atlantic, whereas the ocean currents transport the bergs along the Greenland coast and southward along the Canadian coast. Although the purely atmospheric-forced bergs cause warmer oceanic conditions than the oceanic-driven bergs, the overall effect on climate and the resulting ice sheet due to variations in the
Model-based risk analysis of coupled process steps.
Westerberg, Karin; Broberg-Hansen, Ernst; Sejergaard, Lars; Nilsson, Bernt
2013-09-01
A section of a biopharmaceutical manufacturing process involving the enzymatic coupling of a polymer to a therapeutic protein was characterized with regards to the process parameter sensitivity and design space. To minimize the formation of unwanted by-products in the enzymatic reaction, the substrate was added in small amounts and unreacted protein was separated using size-exclusion chromatography (SEC) and recycled to the reactor. The quality of the final recovered product was thus a result of the conditions in both the reactor and the SEC, and a design space had to be established for both processes together. This was achieved by developing mechanistic models of the reaction and SEC steps, establishing the causal links between process conditions and product quality. Model analysis was used to complement the qualitative risk assessment, and design space and critical process parameters were identified. The simulation results gave an experimental plan focusing on the "worst-case regions" in terms of product quality and yield. In this way, the experiments could be used to verify both the suggested process and the model results. This work demonstrates the necessary steps of model-assisted process analysis, from model development through experimental verification. Copyright © 2013 Wiley Periodicals, Inc.
How to combine sparse proxy data and coupled climate models
Paul, André; Schäfer-Neth, Christian
2005-04-01
We address the problem of reconstructing a global field from proxy data with sparse spatial sampling such as the MARGO (multi-proxy approach for the reconstruction of the glacial ocean surface) SST (sea-surface temperature) and δ18O c (oxygen-18/oxygen-16 isotope ratio preserved in fossil carbonate shells of planktic foraminifera) data. To this end, we propose to `assimilate' these data into coupled climate models by adjusting some of their parameters and optimizing the fit. In particular, we suggest to combine a forward model and an objective function that quantifies the misfit to the data. Because of their computational efficiency, earth system models of intermediate complexity are particularly well-suited for this purpose. We used one such model (the University of Victoria Earth System Climate Model) and carried out a series of sensitivity experiments by varying a single model parameter through changing the atmospheric CO2 concentration. The unanalyzed World Ocean Atlas SST and the observed sea-ice concentration served as present-day targets. The sparse data coverage as implied by the locations of 756 ocean sediment cores from the MARGO SST database was indeed sufficient to determine the best fit. As anticipated, it turned out to be the 365 ppm experiment. We also found that the 200 ppm experiment came surprisingly close to what is commonly expected for the Last Glacial Maximum ocean circulation. Our strategy has a number of advantages over more traditional mapping methods, e.g., there is no need to force the results of different proxies into a single map, because they can be compared to the model output one at a time, properly taking into account the different seasons of plankton growth or varying depth habitats. It can be extended to more model parameters and even be automated.
Modeling of traction-coupling properties of wheel propulsor
Sakhapov, R. L.; Nikolaeva, R. V.; Gatiyatullin, M. H.; Makhmutov, M. M.
2017-12-01
In conditions of operation of aggregates on soils with low bearing capacity, the main performance indicators of their operation are determined by the properties of retaining the functional qualities of the propulsor. Therefore, the parameters of the anti-skid device can not be calculated by only one criterion. The equipment of propellers with anti-skid devices, which allow to reduce the compaction effect of the propulsion device on the soil, seems to be a rational solution to the problem of increasing traction and coupling properties of the driving wheels. The mathematical model is based on the study of the interaction of the driving wheel with anti-skid devices and a deformable bearing surface, which takes into account the wheel diameter, skid coefficient, the parameters of the anti-skid device, the physical and mechanical properties of the soil. As a basic mathematical model that determines the dependence of the coupling properties on the wheel parameters, the model obtained as a result of integration and reflecting the process of soil deformation from the shear stress is adopted. The total value of the resistance forces will determine the force of the hitch pressure on the horizontal soil layers, and the value of its deformation is the degree of wheel slippage. When the anti-skid devices interact with the soil, the traction capacity of the wheel is composed of shear forces, soil shear and soil deformation forces with detachable hooks. As a result of the interaction of the hook with the soil, the latter presses against the walls of the hook with the force equal to the sum of the hook load and the resistance to movement. During operation, the linear dimensions of the hook will decrease, which is not taken into account by the safety factor. Abrasive wear of the thickness of the hook is approximately proportional to the work of friction caused by the movement of the hook when inserted into the soil and slipping the wheel.
Affine group formulation of the Standard Model coupled to gravity
Energy Technology Data Exchange (ETDEWEB)
Chou, Ching-Yi, E-mail: l2897107@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Taiwan (China); Ita, Eyo, E-mail: ita@usna.edu [Department of Physics, US Naval Academy, Annapolis, MD (United States); Soo, Chopin, E-mail: cpsoo@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Taiwan (China)
2014-04-15
In this work we apply the affine group formalism for four dimensional gravity of Lorentzian signature, which is based on Klauder’s affine algebraic program, to the formulation of the Hamiltonian constraint of the interaction of matter and all forces, including gravity with non-vanishing cosmological constant Λ, as an affine Lie algebra. We use the hermitian action of fermions coupled to gravitation and Yang–Mills theory to find the density weight one fermionic super-Hamiltonian constraint. This term, combined with the Yang–Mills and Higgs energy densities, are composed with York’s integrated time functional. The result, when combined with the imaginary part of the Chern–Simons functional Q, forms the affine commutation relation with the volume element V(x). Affine algebraic quantization of gravitation and matter on equal footing implies a fundamental uncertainty relation which is predicated upon a non-vanishing cosmological constant. -- Highlights: •Wheeler–DeWitt equation (WDW) quantized as affine algebra, realizing Klauder’s program. •WDW formulated for interaction of matter and all forces, including gravity, as affine algebra. •WDW features Hermitian generators in spite of fermionic content: Standard Model addressed. •Constructed a family of physical states for the full, coupled theory via affine coherent states. •Fundamental uncertainty relation, predicated on non-vanishing cosmological constant.
Can a coupled meteorology–chemistry model reproduce the ...
The ability of a coupled meteorology–chemistry model, i.e., Weather Research and Forecast and Community Multiscale Air Quality (WRF-CMAQ), to reproduce the historical trend in aerosol optical depth (AOD) and clear-sky shortwave radiation (SWR) over the Northern Hemisphere has been evaluated through a comparison of 21-year simulated results with observation-derived records from 1990 to 2010. Six satellite-retrieved AOD products including AVHRR, TOMS, SeaWiFS, MISR, MODIS-Terra and MODIS-Aqua as well as long-term historical records from 11 AERONET sites were used for the comparison of AOD trends. Clear-sky SWR products derived by CERES at both the top of atmosphere (TOA) and surface as well as surface SWR data derived from seven SURFRAD sites were used for the comparison of trends in SWR. The model successfully captured increasing AOD trends along with the corresponding increased TOA SWR (upwelling) and decreased surface SWR (downwelling) in both eastern China and the northern Pacific. The model also captured declining AOD trends along with the corresponding decreased TOA SWR (upwelling) and increased surface SWR (downwelling) in the eastern US, Europe and the northern Atlantic for the period of 2000–2010. However, the model underestimated the AOD over regions with substantial natural dust aerosol contributions, such as the Sahara Desert, Arabian Desert, central Atlantic and northern Indian Ocean. Estimates of the aerosol direct radiative effect (DRE) at TOA a
Properties of Coupled Oscillator Model for Bidirectional Associative Memory
Kawaguchi, Satoshi
2016-08-01
In this study, we consider the stationary state and dynamical properties of a coupled oscillator model for bidirectional associative memory. For the stationary state, we apply the replica method to obtain self-consistent order parameter equations. The theoretical results for the storage capacity and overlap agree well with the numerical simulation. For the retrieval process, we apply statistical neurodynamics to include temporal noise correlations. For the successful retrieval process, the theoretical result obtained with the fourth-order approximation qualitatively agrees with the numerical simulation. However, for the unsuccessful retrieval process, higher-order noise correlations suppress severely; therefore, the maximum value of the overlap and the relaxation time are smaller than those of the numerical simulation. The reasons for the discrepancies between the theoretical result and numerical simulation, and the validity of our analysis are discussed.
Nuclear pasta phases within the quark-meson coupling model
Grams, Guilherme; Santos, Alexandre M.; Panda, Prafulla K.; Providência, Constança; Menezes, Débora P.
2017-05-01
In this work, the low-density regions of nuclear and neutron star matter are studied. The search for the existence of nuclear pasta phases in this region is performed within the context of the quark-meson coupling (QMC) model, which incorporates quark degrees of freedom. Fixed proton fractions are considered, as well as nuclear matter in β equilibrium at zero temperature. We discuss the recent attempts to better understand the surface energy in the coexistence phases regime and we present results that show the existence of the pasta phases subject to some choices of the surface energy coefficient. We also analyze the influence of the nuclear pasta on some neutron star properties. The equation of state containing the pasta phase will be part of a complete grid for future use in supernova simulations.
Stepwise calibration procedure for regional coupled hydrological-hydrogeological models
Labarthe, Baptiste; Abasq, Lena; de Fouquet, Chantal; Flipo, Nicolas
2014-05-01
Stream-aquifer interaction is a complex process depending on regional and local processes. Indeed, the groundwater component of hydrosystem and large scale heterogeneities control the regional flows towards the alluvial plains and the rivers. In second instance, the local distribution of the stream bed permeabilities controls the dynamics of stream-aquifer water fluxes within the alluvial plain, and therefore the near-river piezometric head distribution. In order to better understand the water circulation and pollutant transport in watersheds, the integration of these multi-dimensional processes in modelling platform has to be performed. Thus, the nested interfaces concept in continental hydrosystem modelling (where regional fluxes, simulated by large scale models, are imposed at local stream-aquifer interfaces) has been presented in Flipo et al (2014). This concept has been implemented in EauDyssée modelling platform for a large alluvial plain model (900km2) part of a 11000km2 multi-layer aquifer system, located in the Seine basin (France). The hydrosystem modelling platform is composed of four spatially distributed modules (Surface, Sub-surface, River and Groundwater), corresponding to four components of the terrestrial water cycle. Considering the large number of parameters to be inferred simultaneously, the calibration process of coupled models is highly computationally demanding and therefore hardly applicable to a real case study of 10000km2. In order to improve the efficiency of the calibration process, a stepwise calibration procedure is proposed. The stepwise methodology involves determining optimal parameters of all components of the coupled model, to provide a near optimum prior information for the global calibration. It starts with the surface component parameters calibration. The surface parameters are optimised based on the comparison between simulated and observed discharges (or filtered discharges) at various locations. Once the surface parameters
Coupled atmosphere-ocean models of Titan's past.
McKay, C P; Pollack, J B; Lunine, J I; Courtin, R
1993-03-01
We have developed a coupled atmosphere and ocean model of Titan's surface. The atmospheric model is a 1-D spectrally-resolved radiative-convective model. The ocean thermodynamics are based upon solution theory. The ocean, initially composed of CH4, becomes progressively enriched in ethane over time. The partial pressures of N2 and CH4 in the atmosphere are dependent on the ocean temperature and composition. We find that the resulting system is stable against a runaway greenhouse. Accounting for the decreased solar luminosity, we find that Titan's surface temperature was about 20 K colder 4 Gyr ago. Without an ocean, but only small CH4 lakes, the temperature change is 12 K. In both cases we find that the surface of Titan may have been ice covered about 3 Gyr ago. In the lakes case condensation of N2 provides the ice, whereas in the ocean case the ocean freezes. The dominant factor influencing the evolution of Titan's surface temperature is the change in the solar constant--amplified, if an ocean is present, by the temperature dependence of the solubility of N2. Accretional heating can dramatically alter the surface temperature; a surface thermal flux of 500 erg cm-2 sec-1, representative of small levels of accretional heating, results in a approximately 20 K change in surface temperatures.
Ising models of strongly coupled biological networks with multivariate interactions
Merchan, Lina; Nemenman, Ilya
2013-03-01
Biological networks consist of a large number of variables that can be coupled by complex multivariate interactions. However, several neuroscience and cell biology experiments have reported that observed statistics of network states can be approximated surprisingly well by maximum entropy models that constrain correlations only within pairs of variables. We would like to verify if this reduction in complexity results from intricacies of biological organization, or if it is a more general attribute of these networks. We generate random networks with p-spin (p > 2) interactions, with N spins and M interaction terms. The probability distribution of the network states is then calculated and approximated with a maximum entropy model based on constraining pairwise spin correlations. Depending on the M/N ratio and the strength of the interaction terms, we observe a transition where the pairwise approximation is very good to a region where it fails. This resembles the sat-unsat transition in constraint satisfaction problems. We argue that the pairwise model works when the number of highly probable states is small. We argue that many biological systems must operate in a strongly constrained regime, and hence we expect the pairwise approximation to be accurate for a wide class of problems. This research has been partially supported by the James S McDonnell Foundation grant No.220020321.
Directory of Open Access Journals (Sweden)
Isa Kolo
2016-01-01
Full Text Available A coupled elastic-plasticity-damage constitutive model, AK Model, is applied to predict fracture propagation in rocks. The quasi-brittle material model captures anisotropic effects and the distinct behavior of rocks in tension and compression. Calibration of the constitutive model is realized using experimental data for Carrara marble. Through the Weibull distribution function, heterogeneity effect is captured by spatially varying the elastic properties of the rock. Favorable comparison between model predictions and experiments for single-flawed specimens reveal that the AK Model is reliable and accurate for modelling fracture propagation in rocks.
Xu, Guangping; Wang, Jiasong
2017-10-01
Two dynamical models, the traditional method of moments coupled model (MCM) and Taylor-series expansion method of moments coupled model (TECM) for particle dispersion distribution and gravitation deposition are developed in three-dimensional ventilated environments. The turbulent airflow field is modeled with the renormalization group (RNG) k-ε turbulence model. The particle number concentration distribution in a ventilated room is obtained by solving the population balance equation coupled with the airflow field. The coupled dynamical models are validated using experimental data. A good agreement between the numerical and experimental results can be achieved. Both models have a similar characteristic for the spatial distribution of particle concentration. Relative to the MCM model, the TECM model presents a more close result to the experimental data. The vortex structure existed in the air flow makes a relative large concentration difference at the center region and results in a spatial non-uniformity of concentration field. With larger inlet velocity, the mixing level of particles in the room is more uniform. In general, the new dynamical models coupled with computational fluid dynamics (CFD) in the current study provide a reasonable and accurate method for the temporal and spatial evolution of particles effected by the deposition and dispersion behaviors. In addition, two ventilation modes with different inlet velocities are proceeded to study the effect on the particle evolution. The results show that with the ceiling ventilation mode (CVM), the particles can be better mixed and the concentration level is also higher. On the contrast, with the side ceiling ventilation mode (SVM), the particle concentration has an obvious stratified distribution with a relative lower level and it makes a much better environment condition to the human exposure.
Modeling of magnetoelastic nanostructures with a fully coupled mechanical-micromagnetic model
Liang, Cheng-Yen; Keller, Scott M.; Sepulveda, Abdon E.; Bur, Alexandre; Sun, Wei-Yang; Wetzlar, Kyle; Carman, Gregory P.
2014-10-01
Micromagnetic simulations of magnetoelastic nanostructures traditionally rely on either the Stoner-Wohlfarth model or the Landau-Lifshitz-Gilbert (LLG) model, assuming uniform strain (and/or assuming uniform magnetization). While the uniform strain assumption is reasonable when modeling magnetoelastic thin films, this constant strain approach becomes increasingly inaccurate for smaller in-plane nanoscale structures. This paper presents analytical work intended to significantly improve the simulation of finite structures by fully coupling the LLG model with elastodynamics, i.e., the partial differential equations are intrinsically coupled. The coupled equations developed in this manuscript, along with the Stoner-Wohlfarth model and the LLG (constant strain) model are compared to experimental data on nickel nanostructures. The nickel nanostructures are 100 × 300 × 35 nm single domain elements that are fabricated on a Si/SiO2 substrate; these nanostructures are mechanically strained when they experience an applied magnetic field, which is used to generate M vs H curves. Results reveal that this paper’s fully-coupled approach corresponds the best with the experimental data on coercive field changes. This more sophisticated modeling technique is critical for guiding the design process of future nanoscale strain-mediated multiferroic elements, such as those needed in memory systems.
Finite element modeling of a 3D coupled foot-boot model.
Qiu, Tian-Xia; Teo, Ee-Chon; Yan, Ya-Bo; Lei, Wei
2011-12-01
Increasingly, musculoskeletal models of the human body are used as powerful tools to study biological structures. The lower limb, and in particular the foot, is of interest because it is the primary physical interaction between the body and the environment during locomotion. The goal of this paper is to adopt the finite element (FE) modeling and analysis approaches to create a state-of-the-art 3D coupled foot-boot model for future studies on biomechanical investigation of stress injury mechanism, foot wear design and parachute landing fall simulation. In the modeling process, the foot-ankle model with lower leg was developed based on Computed Tomography (CT) images using ScanIP, Surfacer and ANSYS. Then, the boot was represented by assembling the FE models of upper, insole, midsole and outsole built based on the FE model of the foot-ankle, and finally the coupled foot-boot model was generated by putting together the models of the lower limb and boot. In this study, the FE model of foot and ankle was validated during balance standing. There was a good agreement in the overall patterns of predicted and measured plantar pressure distribution published in literature. The coupled foot-boot model will be fully validated in the subsequent works under both static and dynamic loading conditions for further studies on injuries investigation in military and sports, foot wear design and characteristics of parachute landing impact in military. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.
A coupled-oscillator model of olfactory bulb gamma oscillations.
Directory of Open Access Journals (Sweden)
Guoshi Li
2017-11-01
Full Text Available The olfactory bulb transforms not only the information content of the primary sensory representation, but also its underlying coding metric. High-variance, slow-timescale primary odor representations are transformed by bulbar circuitry into secondary representations based on principal neuron spike patterns that are tightly regulated in time. This emergent fast timescale for signaling is reflected in gamma-band local field potentials, presumably serving to efficiently integrate olfactory sensory information into the temporally regulated information networks of the central nervous system. To understand this transformation and its integration with interareal coordination mechanisms requires that we understand its fundamental dynamical principles. Using a biophysically explicit, multiscale model of olfactory bulb circuitry, we here demonstrate that an inhibition-coupled intrinsic oscillator framework, pyramidal resonance interneuron network gamma (PRING, best captures the diversity of physiological properties exhibited by the olfactory bulb. Most importantly, these properties include global zero-phase synchronization in the gamma band, the phase-restriction of informative spikes in principal neurons with respect to this common clock, and the robustness of this synchronous oscillatory regime to multiple challenging conditions observed in the biological system. These conditions include substantial heterogeneities in afferent activation levels and excitatory synaptic weights, high levels of uncorrelated background activity among principal neurons, and spike frequencies in both principal neurons and interneurons that are irregular in time and much lower than the gamma frequency. This coupled cellular oscillator architecture permits stable and replicable ensemble responses to diverse sensory stimuli under various external conditions as well as to changes in network parameters arising from learning-dependent synaptic plasticity.
Embedding complex hydrology in the climate system - towards fully coupled climate-hydrology models
DEFF Research Database (Denmark)
Butts, M.; Rasmussen, S.H.; Ridler, M.
2013-01-01
model, HIRHAM. The physics of the coupling is formulated using an energy-based SVAT (land surface) model while the numerical coupling exploits the OpenMI modelling interface. First, some investigations of the applicability of the SVAT model are presented, including our ability to characterise...
Embedding complex hydrology in the climate system - Towards fully coupled climate-hydrology models
DEFF Research Database (Denmark)
Butts, Michael; Rasmussen, Søren H.; Ridler, Marc
2013-01-01
model, HIRHAM. The physics of the coupling is formulated using an energy-based SVAT (land surface) model while the numerical coupling exploits the OpenMI modelling interface. First, some investigations of the applicability of the SVAT model are presented, including our ability to characterise...
Permutation Complexity and Coupling Measures in Hidden Markov Models
Directory of Open Access Journals (Sweden)
Taichi Haruna
2013-09-01
Full Text Available Recently, the duality between values (words and orderings (permutations has been proposed by the authors as a basis to discuss the relationship between information theoretic measures for finite-alphabet stationary stochastic processes and their permutatio nanalogues. It has been used to give a simple proof of the equality between the entropy rate and the permutation entropy rate for any finite-alphabet stationary stochastic process and to show some results on the excess entropy and the transfer entropy for finite-alphabet stationary ergodic Markov processes. In this paper, we extend our previous results to hidden Markov models and show the equalities between various information theoretic complexity and coupling measures and their permutation analogues. In particular, we show the following two results within the realm of hidden Markov models with ergodic internal processes: the two permutation analogues of the transfer entropy, the symbolic transfer entropy and the transfer entropy on rank vectors, are both equivalent to the transfer entropy if they are considered as the rates, and the directed information theory can be captured by the permutation entropy approach.
A coupled thermo-mechanical model of friction stir welding
Directory of Open Access Journals (Sweden)
Veljić Darko M.
2012-01-01
Full Text Available A coupled thermo-mechanical model was developed to study the temperature fields, the plunge force and the plastic deformations of Al alloy 2024-T351 under different rotating speed: 350, 400 and 450 rpm, during the friction stir welding (FSW process. Three-dimensional FE model has been developed in ABAQUS/Explicit using the arbitrary Lagrangian-Eulerian formulation, the Johnson-Cook material law and the Coulomb’s Law of friction. Numerical results indicate that the maximum temperature in the FSW process is lower than the melting point of the welding material. The temperature filed is approximately symmetrical along the welding line. A lower plastic strain region can be found near the welding tool in the trailing side on the bottom surface. With increasing rotation speed, the low plastic strain region is reduced. When the rotational speed is increased, the plunge force can be reduced. Regions with high equivalent plastic strains are observed which correspond to the nugget and the flow arm.
Particle model of a cylindrical inductively coupled ion source
Ippolito, N. D.; Taccogna, F.; Minelli, P.; Cavenago, M.; Veltri, P.
2017-08-01
In spite of the wide use of RF sources, a complete understanding of the mechanisms regulating the RF-coupling of the plasma is still lacking so self-consistent simulations of the involved physics are highly desirable. For this reason we are developing a 2.5D fully kinetic Particle-In-Cell Monte-Carlo-Collision (PIC-MCC) model of a cylindrical ICP-RF source, keeping the time step of the simulation small enough to resolve the plasma frequency scale. The grid cell dimension is now about seven times larger than the average Debye length, because of the large computational demand of the code. It will be scaled down in the next phase of the development of the code. The filling gas is Xenon, in order to minimize the time lost by the MCC collision module in the first stage of development of the code. The results presented here are preliminary, with the code already showing a good robustness. The final goal will be the modeling of the NIO1 (Negative Ion Optimization phase 1) source, operating in Padua at Consorzio RFX.
A Coupled THMC model of FEBEX mock-up test
Energy Technology Data Exchange (ETDEWEB)
Zheng, Liange; Samper, Javier
2008-09-15
FEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project for the engineered barrier system (EBS) of a radioactive waste repository in granite. It includes two full-scale heating and hydration tests: the in situ test performed at Grimsel (Switzerland) and a mock-up test operating at CIEMAT facilities in Madrid (Spain). The mock-up test provides valuable insight on thermal, hydrodynamic, mechanical and chemical (THMC) behavior of EBS because its hydration is controlled better than that of in situ test in which the buffer is saturated with water from the surrounding granitic rock. Here we present a coupled THMC model of the mock-up test which accounts for thermal and chemical osmosis and bentonite swelling with a state-surface approach. The THMC model reproduces measured temperature and cumulative water inflow data. It fits also relative humidity data at the outer part of the buffer, but underestimates relative humidities near the heater. Dilution due to hydration and evaporation near the heater are the main processes controlling the concentration of conservative species while surface complexation, mineral dissolution/precipitation and cation exchanges affect significantly reactive species as well. Results of sensitivity analyses to chemical processes show that pH is mostly controlled by surface complexation while dissolved cations concentrations are controlled by cation exchange reactions.
Importance of Vibronic Effects in the UV-Vis Spectrum of the 7,7,8,8-Tetracyanoquinodimethane Anion.
Tapavicza, Enrico; Furche, Filipp; Sundholm, Dage
2016-10-11
We present a computational method for simulating vibronic absorption spectra in the ultraviolet-visible (UV-vis) range and apply it to the 7,7,8,8-tetracyanoquinodimethane anion (TCNQ(-)), which has been used as a ligand in black absorbers. Gaussian broadening of vertical electronic excitation energies of TCNQ(-) from linear-response time-dependent density functional theory produces only one band, which is qualitatively incorrect. Thus, the harmonic vibrational modes of the two lowest doublet states were computed, and the vibronic UV-vis spectrum was simulated using the displaced harmonic oscillator approximation, the frequency-shifted harmonic oscillator approximation, and the full Duschinsky formalism. An efficient real-time generating function method was implemented to avoid the exponential complexity of conventional Franck-Condon approaches to vibronic spectra. The obtained UV-vis spectra for TCNQ(-) agree well with experiment; the Duschinsky rotation is found to have only a minor effect on the spectrum. Born-Oppenheimer molecular dynamics simulations combined with calculations of the electronic excitation energies for a large number of molecular structures were also used for simulating the UV-vis spectrum. The Born-Oppenheimer molecular dynamics simulations yield a broadening of the energetically lowest peak in the absorption spectrum, but additional vibrational bands present in the experimental and simulated quantum harmonic oscillator spectra are not observed in the molecular dynamics simulations. Our results underline the importance of vibronic effects for the UV-vis spectrum of TCNQ(-), and they establish an efficient method for obtaining vibronic spectra using a combination of linear-response time-dependent density functional theory and a real-time generating function approach.
From strong to weak coupling in holographic models of thermalization
Energy Technology Data Exchange (ETDEWEB)
Grozdanov, Sašo; Kaplis, Nikolaos [Instituut-Lorentz for Theoretical Physics, Leiden University,Niels Bohrweg 2, Leiden 2333 CA (Netherlands); Starinets, Andrei O. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom)
2016-07-29
We investigate the analytic structure of thermal energy-momentum tensor correlators at large but finite coupling in quantum field theories with gravity duals. We compute corrections to the quasinormal spectra of black branes due to the presence of higher derivative R{sup 2} and R{sup 4} terms in the action, focusing on the dual to N=4 SYM theory and Gauss-Bonnet gravity. We observe the appearance of new poles in the complex frequency plane at finite coupling. The new poles interfere with hydrodynamic poles of the correlators leading to the breakdown of hydrodynamic description at a coupling-dependent critical value of the wave-vector. The dependence of the critical wave vector on the coupling implies that the range of validity of the hydrodynamic description increases monotonically with the coupling. The behavior of the quasinormal spectrum at large but finite coupling may be contrasted with the known properties of the hierarchy of relaxation times determined by the spectrum of a linearized kinetic operator at weak coupling. We find that the ratio of a transport coefficient such as viscosity to the relaxation time determined by the fundamental non-hydrodynamic quasinormal frequency changes rapidly in the vicinity of infinite coupling but flattens out for weaker coupling, suggesting an extrapolation from strong coupling to the kinetic theory result. We note that the behavior of the quasinormal spectrum is qualitatively different depending on whether the ratio of shear viscosity to entropy density is greater or less than the universal, infinite coupling value of ℏ/4πk{sub B}. In the former case, the density of poles increases, indicating a formation of branch cuts in the weak coupling limit, and the spectral function shows the appearance of narrow peaks. We also discuss the relation of the viscosity-entropy ratio to conjectured bounds on relaxation time in quantum systems.
Coupled Hydro-Damage Modeling of Fluid Injection
Shalev, E.; Lyakhovsky, V.
2012-12-01
Hydraulic fracturing by wellbore fluid injection is widely used to increase permeability in hydrocarbon and geothermal reservoirs but is a complex processes to model numerically. We model hydraulic fracturing with state of the art Hydro-PED software that uses the Finite Element Method for the groundwater flow equation and the Fast Lagrangian Analysis of Continua method for the solid deformation equation. A circular domain with a radius of 100m is used for all simulations. Fluid is injected at the center of the domain into well with radius of 20cm. The initial stress (127.5 MPa) and pore pressure (49 MPa) assigned for the entire domain represent their values at depth of 5 km. Fluid is injected with overpressure of 50 MPa. Damage propagates away from the injection well in the center of the circle and creates two fractures. At early stages, two sets of conjugate fractures began to develop until the one at 68.50 created stress shadow that stopped its conjugate pair. The pore pressure increases mainly within the hydrofractures where the damage related permeability is high. The only pore pressure changes occurring in the undamaged rock result from poro-elastic effects of the advancing fractures, similar to the mean stress. The fractures advance while creating seismic events whenever the damage parameter is equal to one. Seismicity starts after few hours of injection and occurs continuously along the entire fractures. Fracture propagation accelerates initially and then remains at a constant pace before decelerating. The duration of each phase depends on the permeability-damage coupling. When the coupling is strong, permeability within the damaged fracture is high allowing high pore pressure and longer acceleration phase. As the fracture length increases, the ability of the fracture to transfer fluids to its tip decreases, and the propagation decelerate. While the pore pressure at the fracture's tip >90% of the overpressure, the subcritical fracture's growth increases with
Coupled model of root water uptake, mucilage exudation and degradation
Kroener, Eva; Ahmed, Mutez A.; Carminati, Andrea
2017-04-01
Although the fact that root mucilage plays a prominent role in soil-plant water relations is becoming more and more accepted, many aspects of how mucilage distribution and root water uptake interact with each other remain unexplored. First, it is not clear how long mucilage persists in soil. Furthermore, the effects of water content and root water uptake (i.e. convective fluxes) on the diffusion of mucilage from the root surface into the soil are not included in current models of water uptake. The aims of this study were: i) to measure the effect of soil moisture on mucilage decomposition; ii) to develop a coupled model of root water uptake and mucilage diffusion and degradation during root growth. C4 root mucilage from maize was added as single pulses to a C3 soil of two different moisture levels. We have then employed the Richards Equation for water flow and an advection-dispersion equation to describe the dynamic distribution of mucilage in a single-root model. Most of the mucilage was decomposed under optimum water supply. Drought significantly suppressed mucilage mineralization. Opposed to classical solute transport models the water flow in the rhizosphere was affected by the local concentration of mucilage. Namely a higher concentration of mucilage results in (a) an increase in equilibrium water retention curve, (b) a reduction of hydraulic conductivity at a given water content and (c) a non-equilibrium water retention curve caused by swelling and shrinking dynamics of mucilage in the pore space. The dispersion coefficient, on the other hand, depends on the water content. The parameters of mucilage diffusion have been fitted to observations on real plants. The model shows that mucilage exuded in wet soils diffuses far from the roots and it is rapidly degraded. On the contrary, mucilage of plants growing in dry soil is not easily degradable and it remains at higher concentrations in a narrow region around the roots, resulting in a marked increase in water
Huisman, J.A.; Rings, J.; Vrugt, J.A.; Sorg, J.; Vereecken, H.
2010-01-01
Coupled hydrogeophysical inversion aims to improve the use of geophysical data for hydrological model parameterization. Several numerical studies have illustrated the feasibility and advantages of a coupled approach. However, there is still a lack of studies that apply the coupled inversion approach
Multimode Jahn-Teller and pseudo-Jahn-Teller coupling effects in the photoelectron spectrum of CH 3F
Mahapatra, S.; Vallet, V.; Woywod, C.; Köppel, H.; Domcke, W.
2004-09-01
The multimode Jahn-Teller (JT) and pseudo-Jahn-Teller (PJT) coupling effects in the photoelectron spectrum of methylfluoride are theoretically investigated with the aid of an ab initio quantum dynamical approach. The theoretical findings are compared with the experimental results of Karlsson et al. [Phys. Scripta 16 (1977) 225]. At the vertical configuration, the ground, first and second excited electronic states of the methylfluoride radical cation belong to the 2E, 2A 1 and 2E symmetry species. The three doubly degenerate vibrational modes cause a splitting of the degeneracy of the E electronic states of the radical cation and exhibit the (E⊗e)-JT effect. The same vibrational modes may also cause a coupling of the degenerate and the non-degenerate electronic states (PJT effect). In our theoretical approach we devise a model diabatic vibronic Hamiltonian within a quadratic vibronic coupling scheme. The parameters of the Hamiltonian are derived by performing extensive ab initio calculations at the CASSCF-MR-AQCC level of theory. The photoelectron bands are calculated by a quantum dynamical approach based on the Lanczos algorithm. A detailed examination of the various static and dynamic aspects of the problem reveals an interesting interplay of JT and PJT coupling effects in the photoelectron-induced dynamics of CH 3F +. The resolved progression in the first photoelectron band corresponding to the ground X˜2E electronic manifold of CH 3F + is found to be mainly caused by the C-F stretching (a 1), C-F bending (e) and CH 3 deformation (e) modes. The JT coupling effects are not particularly strong in this electronic manifold. This also holds for the second photoelectron band attributed to the vibronic structure of the Ã2A1 and B˜2E electronic states of CH 3F +. However, the extremely large Condon activity of the symmetric vibrational modes in the Ã2A1 electronic state contributes much to the broad and highly diffuse nature of this band which is also observed
Mashauri, D. A.; Kayombo, S.
Recent work has emphasized the potential importance of the constructed wetland systems for purification of effluents from secondary biological treatment plants for prevention of pollution to the receiving water bodies. A model for transformation of organic carbon in facultative pond (FP) was formulated and was coupled with a model of organic carbon transformation in the constructed wetland (CW) for downstream water resources management. The main essence of coupling the model was to have simultaneous simulation of PFP and CW processes. Simultaneous run of the two models imply that the disturbance on parameters in PFP will have a direct effect on CW processes. The model was formulated on the basis fundamental principle that the growth of active biomass in the system defines the transformation of organic carbon. The growth rate of microorganisms was model based on the Monod kinetic equation. The forcing functions to the model were formulated based on multiplicative function. The removal of organic carbon in the FP based on the unfiltered sample was 66% with an average concentration of 206 mg COD/l in the effluent. The removal of organic carbon in the CW was 87.5% with an average concentration of 40 mg COD/l in the effluent. The overall performance of the coupled model was 93%. The main processes of organic carbon removal in the FP and CW were due to uptake by heterotrophic bacteria followed by oxidation. It was found that 80% of the total organic carbon in the CW was due to the biological growth. Oxidation of organic carbon in the PFP was a source of high growth of algae. The constants and coefficients obtained after validation of the model reflect the simultaneous performance of the coupled model of PFP and CW.
Phase Transition Couplings in the Higgsed Monopole Model
Laperashvili, L V
1999-01-01
Using a one-loop approximation for the effective potential in the Higgs model of electrodynamics for a charged scalar field, we argue for the existence of a triple point for the renormalized (running) values of the selfinteraction beta-function as a typical quantity we estimate that the one-loop approximation is valid with accuracy of deviations not more than 30% in the region of the parameters: $0.2 \\stackrel{<}{\\sim}{\\large \\alpha, \\tilde{\\alpha}} corresponds to the above-mentioned region of $\\alpha, \\tilde \\alpha$. Under the point of view that the Higgs particle is a monopole with a magnetic charge g, the obtained electric fine structure constant turns out to be to the $\\alpha_{crit}^{lat}\\approx{0.20}$ which in a U(1) lattice gauge theory corresponds to the phase transition between the "Coulomb" and confinement phases. Such a result is very encouraging for the idea of an approximate "universality" (regularization independence) of gauge couplings at the phase transition point. This idea was suggested by...
A coupled DEM-CFD method for impulse wave modelling
Zhao, Tao; Utili, Stefano; Crosta, GiovanBattista
2015-04-01
Rockslides can be characterized by a rapid evolution, up to a possible transition into a rock avalanche, which can be associated with an almost instantaneous collapse and spreading. Different examples are available in the literature, but the Vajont rockslide is quite unique for its morphological and geological characteristics, as well as for the type of evolution and the availability of long term monitoring data. This study advocates the use of a DEM-CFD framework for the modelling of the generation of hydrodynamic waves due to the impact of a rapid moving rockslide or rock-debris avalanche. 3D DEM analyses in plane strain by a coupled DEM-CFD code were performed to simulate the rockslide from its onset to the impact with still water and the subsequent wave generation (Zhao et al., 2014). The physical response predicted is in broad agreement with the available observations. The numerical results are compared to those published in the literature and especially to Crosta et al. (2014). According to our results, the maximum computed run up amounts to ca. 120 m and 170 m for the eastern and western lobe cross sections, respectively. These values are reasonably similar to those recorded during the event (i.e. ca. 130 m and 190 m respectively). In these simulations, the slope mass is considered permeable, such that the toe region of the slope can move submerged in the reservoir and the impulse water wave can also flow back into the slope mass. However, the upscaling of the grains size in the DEM model leads to an unrealistically high hydraulic conductivity of the model, such that only a small amount of water is splashed onto the northern bank of the Vajont valley. The use of high fluid viscosity and coarse grain model has shown the possibility to model more realistically both the slope and wave motions. However, more detailed slope and fluid properties, and the need for computational efficiency should be considered in future research work. This aspect has also been
Coupling hydrodynamic and wave propagation modeling for waveform modeling of SPE.
Larmat, C. S.; Steedman, D. W.; Rougier, E.; Delorey, A.; Bradley, C. R.
2015-12-01
The goal of the Source Physics Experiment (SPE) is to bring empirical and theoretical advances to the problem of detection and identification of underground nuclear explosions. This paper presents effort to improve knowledge of the processes that affect seismic wave propagation from the hydrodynamic/plastic source region to the elastic/anelastic far field thanks to numerical modeling. The challenge is to couple the prompt processes that take place in the near source region to the ones taking place later in time due to wave propagation in complex 3D geologic environments. In this paper, we report on results of first-principles simulations coupling hydrodynamic simulation codes (Abaqus and CASH), with a 3D full waveform propagation code, SPECFEM3D. Abaqus and CASH model the shocked, hydrodynamic region via equations of state for the explosive, borehole stemming and jointed/weathered granite. LANL has been recently employing a Coupled Euler-Lagrange (CEL) modeling capability. This has allowed the testing of a new phenomenological model for modeling stored shear energy in jointed material. This unique modeling capability has enabled highfidelity modeling of the explosive, the weak grout-filled borehole, as well as the surrounding jointed rock. SPECFEM3D is based on the Spectral Element Method, a direct numerical method for full waveform modeling with mathematical accuracy (e.g. Komatitsch, 1998, 2002) thanks to its use of the weak formulation of the wave equation and of high-order polynomial functions. The coupling interface is a series of grid points of the SEM mesh situated at the edge of the hydrodynamic code domain. Displacement time series at these points are computed from output of CASH or Abaqus (by interpolation if needed) and fed into the time marching scheme of SPECFEM3D. We will present validation tests and waveforms modeled for several SPE tests conducted so far, with a special focus on effect of the local topography.
South African seasonal rainfall prediction performance by a coupled ocean-atmosphere model
CSIR Research Space (South Africa)
Landman, WA
2010-12-01
Full Text Available Evidence is presented that coupled ocean-atmosphere models can already outscore computationally less expensive atmospheric models. However, if the atmospheric models are forced with highly skillful SST predictions, they may still be a very strong...
Nonlinear interaction between underwater explosion bubble and structure based on fully coupled model
Zhang, A. M.; Wu, W. B.; Liu, Y. L.; Wang, Q. X.
2017-08-01
The interaction between an underwater explosion bubble and an elastic-plastic structure is a complex transient process, accompanying violent bubble collapsing, jet impact, penetration through the bubble, and large structural deformation. In the present study, the bubble dynamics are modeled using the boundary element method and the nonlinear transient structural response is modeled using the explicit finite element method. A new fully coupled 3D model is established through coupling the equations for the state variables of the fluid and structure and solving them as a set of coupled linear algebra equations. Based on the acceleration potential theory, the mutual dependence between the hydrodynamic load and the structural motion is decoupled. The pressure distribution in the flow field is calculated with the Bernoulli equation, where the partial derivative of the velocity potential in time is calculated using the boundary integral method to avoid numerical instabilities. To validate the present fully coupled model, the experiments of small-scale underwater explosion near a stiffened plate are carried out. High-speed imaging is used to capture the bubble behaviors and strain gauges are used to measure the strain response. The numerical results correspond well with the experimental data, in terms of bubble shapes and structural strain response. By both the loosely coupled model and the fully coupled model, the interaction between a bubble and a hollow spherical shell is studied. The bubble patterns vary with different parameters. When the fully coupled model and the loosely coupled model are advanced with the same time step, the error caused by the loosely coupled model becomes larger with the coupling effect becoming stronger. The fully coupled model is more stable than the loosely coupled model. Besides, the influences of the internal fluid on the dynamic response of the spherical shell are studied. At last, the case that the bubble interacts with an air
DEFF Research Database (Denmark)
Larsen, Morten Andreas Dahl; Drews, Martin; Hesselbjerg Christensen, Jens
convective precipitation systems. As a result climate model simulations let alone future projections of precipitation often exhibit substantial biases. Here we show that the dynamical coupling of a regional climate model to a detailed fully distributed hydrological model - including groundwater-, overland...... of local precipitation dynamics are seen for time scales of app. Seasonal duration and longer. We show that these results can be attributed to a more complete treatment of land surface feedbacks. The local scale effect on the atmosphere suggests that coupled high-resolution climate-hydrology models...... including a detailed 3D redistribution of sub- and land surface water have a significant potential for improving climate projections even diminishing the need for bias correction in climate-hydrology studies....
Coupled electromechanical model of an imperfect piezoelectric vibrating cylinder gyroscope
CSIR Research Space (South Africa)
Loveday, PW
1996-01-01
Full Text Available Coupled electromechanical equations of motion, describing the dynamics of a vibrating cylinder gyroscope, are derived using Hamilton's principle and the Rayleigh-Ritz method. The vibrating cylinder gyroscope comprises a thin walled steel cylinder...
Coupled flare attractors – a discrete prototype for economic modelling
Directory of Open Access Journals (Sweden)
Georg C. Hartmann
1999-01-01
Full Text Available A chaotic environment can give rise to “flares” if an autocatalytic variable responds in a multiplicative, threshold-type fashion to the environmental forcing. An “economic unit” similarly depends in its growth behavior on the unpredictable (chaotic? buying habits of its customers, say. It turns out that coupled flare attractors are surprisingly robust in the sense that the resulting “economy” is largely independent of the extent of diffusive coupling used. Some simulations are presented.
Modeling of the Coupled Magnetospheric and Neutral Wind Dynamos
Thayer, Jeffrey P.
1997-01-01
the magnetosphere. The influence of the neutral wind was then determined not by estimating how much electric potential or current density it provides, but by determining the contribution of the neutral wind to the net electromagnetic energy transferred between the ionosphere and magnetosphere. The estimate of the net electromagnetic energy transfer and the role of the neutral winds proves to be a more fundamental quantity in studies of magnetosphere- ionosphere coupling also showed that by using electric and magnetic field measurements from the HILAT satellite, the Poynting flux could be a measurable quantity from polar-orbiting, low- altitude spacecraft. Through collaboration with Dr. Heelis and others at UTD and their expertise of the electric field measurements on the DE-B satellite, an extensive analysis was planned to determine the Poynting flux from the DE-B measurements in combination with a modeling effort to help interpret the observations taking into account the coupled magnetosphere-ionosphere.
Drift-Scale Coupled Processes (DST and TH Seepage) Models
Energy Technology Data Exchange (ETDEWEB)
J. Birkholzer; S. Mukhopadhyay
2004-09-29
The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report.
Analysis of Neural-BOLD Coupling through Four Models of the Neural Metabolic Demand
Directory of Open Access Journals (Sweden)
Christopher W Tyler
2015-12-01
Full Text Available The coupling of the neuronal energetics to the blood-oxygen-level-dependent (BOLD response is still incompletely understood. To address this issue, we compared the fits of four plausible models of neurometabolic coupling dynamics to available data for simultaneous recordings of the local field potential (LFP and the local BOLD response recorded from monkey primary visual cortex over a wide range of stimulus durations. The four models of the metabolic demand driving the BOLD response were: direct coupling with the overall LFP; rectified coupling to the LFP; coupling with a slow adaptive component of the implied neural population response; and coupling with the non-adaptive intracellular input signal defined by the stimulus time course. Taking all stimulus durations into account, the results imply that the BOLD response is most closely coupled with metabolic demand derived from the intracellular input waveform, without significant influence from the adaptive transients and nonlinearities exhibited by the LFP waveform.
GeoFramework: Coupling multiple models of mantle convection within a computational framework
Tan, E.; Choi, E.; Thoutireddy, P.; Gurnis, M.; Aivazis, M.
2006-06-01
Solver coupling can extend the capability of existing modeling software and provide a new venue to address previously intractable problems. A software package has been developed to couple geophysical solvers, demonstrating a method to accurately and efficiently solve multiscale geophysical problems with reengineered software using a computational framework (Pyre). Pyre is a modeling framework capable of handling all aspects of the specification and launching of numerical investigations. We restructured and ported CitcomS, a finite element code for mantle convection, into the Pyre framework. Two CitcomS solvers are coupled to investigate the interaction of a plume at high resolution with global mantle flow at low resolution. A comparison of the coupled models with parameterized models demonstrates the accuracy and efficiency of the coupled models and illustrates the limitations and utility of parameterized models.
Multi-year predictability in a coupled general circulation model
Energy Technology Data Exchange (ETDEWEB)
Power, Scott; Colman, Rob [Bureau of Meteorology Research Centre, Melbourne, VIC (Australia)
2006-02-01
Multi-year to decadal variability in a 100-year integration of a BMRC coupled atmosphere-ocean general circulation model (CGCM) is examined. The fractional contribution made by the decadal component generally increases with depth and latitude away from surface waters in the equatorial Indo-Pacific Ocean. The relative importance of decadal variability is enhanced in off-equatorial ''wings'' in the subtropical eastern Pacific. The model and observations exhibit ''ENSO-like'' decadal patterns. Analytic results are derived, which show that the patterns can, in theory, occur in the absence of any predictability beyond ENSO time-scales. In practice, however, modification to this stochastic view is needed to account for robust differences between ENSO-like decadal patterns and their interannual counterparts. An analysis of variability in the CGCM, a wind-forced shallow water model, and a simple mixed layer model together with existing and new theoretical results are used to improve upon this stochastic paradigm and to provide a new theory for the origin of decadal ENSO-like patterns like the Interdecadal Pacific Oscillation and Pacific Decadal Oscillation. In this theory, ENSO-driven wind-stress variability forces internal equatorially-trapped Kelvin waves that propagate towards the eastern boundary. Kelvin waves can excite reflected internal westward propagating equatorially-trapped Rossby waves (RWs) and coastally-trapped waves (CTWs). CTWs have no impact on the off-equatorial sub-surface ocean outside the coastal wave guide, whereas the RWs do. If the frequency of the incident wave is too high, then only CTWs are excited. At lower frequencies, both CTWs and RWs can be excited. The lower the frequency, the greater the fraction of energy transmitted to RWs. This lowers the characteristic frequency of variability off the equator relative to its equatorial counterpart. Both the eastern boundary interactions and the accumulation of
PyMT: A Python package for model-coupling in the Earth sciences
Hutton, E.
2016-12-01
The current landscape of Earth-system models is not only broad in scientific scope, but also broad in type. On the one hand, the large variety of models is exciting, as it provides fertile ground for extending or linking models together in novel ways to answer new scientific questions. However, the heterogeneity in model type acts to inhibit model coupling, model development, or even model use. Existing models are written in a variety of programming languages, operate on different grids, use their own file formats (both for input and output), have different user interfaces, have their own time steps, etc. Each of these factors become obstructions to scientists wanting to couple, extend - or simply run - existing models. For scientists whose main focus may not be computer science these barriers become even larger and become significant logistical hurdles. And this is all before the scientific difficulties of coupling or running models are addressed. The CSDMS Python Modeling Toolkit (PyMT) was developed to help non-computer scientists deal with these sorts of modeling logistics. PyMT is the fundamental package the Community Surface Dynamics Modeling System uses for the coupling of models that expose the Basic Modeling Interface (BMI). It contains: Tools necessary for coupling models of disparate time and space scales (including grid mappers) Time-steppers that coordinate the sequencing of coupled models Exchange of data between BMI-enabled models Wrappers that automatically load BMI-enabled models into the PyMT framework Utilities that support open-source interfaces (UGRID, SGRID,CSDMS Standard Names, etc.) A collection of community-submitted models, written in a variety of programminglanguages, from a variety of process domains - but all usable from within the Python programming language A plug-in framework for adding additional BMI-enabled models to the framework In this presentation we intoduce the basics of the PyMT as well as provide an example of coupling
Cevizovic, Dalibor; Galovic, Slobodanka; Ivic, Zoran
2012-01-01
We present a study of the physical properties of the vibrational excitation in the one-dimensional macromolecular chains, caused by the interaction with acoustical phonon modes. The influence of the temperature and the basic system parameters on the vibron dressing has been analyzed by employing the simple mean--field approach based on the variational extension of the Lang--Firsov unitary transformation. Applied approach predicts a region in system parameter space where it is possible of the coexistence of the partially dressed (light and mobile) and fully dressed (immobile) vibron states. We found that the boundary of this region depends on system temperature and type of bond among structure elements in macromolecular chain.
Newby, Josh J; Liu, Ching-Ping; Müller, Christian W; Zwier, Timothy S
2009-10-01
The vibronic excitation spectrum of phenylcyclopenta-1,3-diene (PCP3D) has been recorded in a supersonic expansion using resonant-two-photon ionization (R2PI) and laser-induced fluorescence (LIF) techniques. The spectrum is dominated by the S(0)-S(1) origin transition (31,739 cm(-1)), with several low-frequency vibronic bands in the first 400 cm(-1), followed by a sharp cut-off in intensity due to turn-on of a non-radiative process. Single vibronic level fluorescence (SVLF) spectra were recorded for the S(1) origin and several vibronic bands of PCP3D. The excitation and emission spectra show that the molecule is planar with C(s) symmetry in both the ground and excited states. Torsional potentials were simulated from the observed torsional structure in the excitation and emission spectra. The S(0) potential (V(2) = 1237 cm(-1), V(4) = -256 cm(-1)) is associated with a flat-bottomed potential supporting large inter-ring angular changes with little cost in energy (+/-36 degrees at 200 cm(-1)), with a barrier of 1237 cm(-1) at the perpendicular geometry. The S(1) potential is much stiffer about the planar geometry, with a calculated barrier five times larger than in S(0) (V(2) = 6732 cm(-1), V(4) = -477 cm(-1)). Based on the torsional assignments, weak bands in the same frequency region assigned earlier to the structural isomer phenylcyclopenta-1,4-diene [J. J. Newby, J. A. Stearns, C. P. Liu and T. S. Zwier, J. Phys. Chem. A, 2007, 111, 10914-10927] have been re-assigned as hot bands arising from v'' = 1 in the inter-ring torsion, nu(57).
Topic models: A novel method for modeling couple and family text data
Atkins, David C.; Rubin, Tim N.; Steyvers, Mark; Doeden, Michelle A.; Baucom, Brian R.; Christensen, Andrew
2012-01-01
Couple and family researchers often collect open-ended linguistic data – either through free response questionnaire items or transcripts of interviews or therapy sessions. Because participant's responses are not forced into a set number of categories, text-based data can be very rich and revealing of psychological processes. At the same time it is highly unstructured and challenging to analyze. Within family psychology analyzing text data typically means applying a coding system, which can quantify text data but also has several limitations, including the time needed for coding, difficulties with inter-rater reliability, and defining a priori what should be coded. The current article presents an alternative method for analyzing text data called topic models (Steyvers & Griffiths, 2006), which has not yet been applied within couple and family psychology. Topic models have similarities with factor analysis and cluster analysis in that topic models identify underlying clusters of words with semantic similarities (i.e., the “topics”). In the present article, a non-technical introduction to topic models is provided, highlighting how these models can be used for text exploration and indexing (e.g., quickly locating text passages that share semantic meaning) and how output from topic models can be used to predict behavioral codes or other types of outcomes. Throughout the article a collection of transcripts from a large couple therapy trial (Christensen et al., 2004) is used as example data to highlight potential applications. Practical resources for learning more about topic models and how to apply them are discussed. PMID:22888778
Self-similar solution for coupled thermal electromagnetic model ...
African Journals Online (AJOL)
An investigation into the existence and uniqueness solution of self-similar solution for the coupled Maxwell and Pennes Bio-heat equations have been done. Criteria for existence and uniqueness of self-similar solution are revealed in the consequent theorems. Journal of the Nigerian Association of Mathematical Physics ...
Calculations of NMR dipolar coupling strengths in model peptides
Energy Technology Data Exchange (ETDEWEB)
Case, David A. [Scripps Research Institute, Department of Molecular Biology (United States)], E-mail: case@scripps.edu
1999-10-15
Ab initio MP2 and density functional quantum chemistry calculations are used to explore geometries and vibrational properties of N-methylacetamide and of the alanine dipeptide with backbone angles characteristic of helix and sheet regions in proteins. The results are used to explore one-bond direct dipolar couplings for the N-H, C{alpha}-H{alpha}, C'-N, and C{alpha}-C' bonds, as well as for the two-bond C'-H interaction. Vibrational averaging affects these dipolar couplings, and these effects can be expressed as effective bond lengths that are 0.5-3% larger than the true bond lengths; bending and torsion vibrations have a bigger influence on the effective coupling than do stretching vibrations. Because of zero-point motion, these effects are important even at low temperature. Hydrogen bonding interactions at the amide group also increase the N-H effective bond length. Although vibrational contributions to effective bond lengths are small, they can have a significant influence on the extraction of order parameters from relaxation data, and a knowledge of relative bond lengths is needed when several types of dipolar couplings are to be simultaneously used for refinement. The present computational results are compared to both solid- and liquid-state NMR experiments. The analysis suggests that secondary structural elements in many proteins may be more rigid than is commonly thought.
Toward external coupling of building energy and airflow modeling programs
Djunaedy, E.; Hensen, J.L.M.; Loomans, M.G.L.C.
2003-01-01
This paper presents the objectives and results of the initial stage of an ongoing research project on coupling of building energy simulation (BES), airflow network (AFN), and compu-tational Huid dynamics (CFD) programs. The objective of the research underlying this paper is to develop and verifi, a
Examination of a Theoretical Model of Streaming Potential Coupling Coefficient
Luong, D.T.; Sprik, R.
2014-01-01
Seismoelectric effects and streaming potentials play an important role in geophysical applications. The key parameter for those phenomena is the streaming potential coupling coefficient, which is, for example, dependent on the zeta potential of the interface of the porous rocks. Comparison of an
Investigating conceptual models for physical property couplings in solid solution models of cement
Energy Technology Data Exchange (ETDEWEB)
Benbow, Steven; Watson, Claire; Savage, David [Quintesssa Ltd., Henley-on-Thames (United Kingdom)
2005-11-15
The long-term behaviour of cementitious engineered barriers is an important process to consider when modelling the migration of radionuclides from a geological repository for nuclear waste. The modelling of cement is complicated by the fact that the cement is dominated by the behaviour of calcium silicate hydrate (CSH) gel which is a complex solid exhibiting incongruent dissolution behaviour. In this report, we have demonstrated the implementation of a solid-solution CSH gel model within a geochemical transport modelling framework using the Raiden computer code to investigate cement/concrete-groundwater interactions. The modelling conducted here shows that it is possible to couple various conceptual models for the evolution of physical properties of concrete with a solid solution model for cement degradation in a fully coupled geochemical transport model to describe the interaction of cement/concrete engineered barriers with groundwater. The results show that changes to the conceptual models and flow rates can give rise to very different evolutions. Most simulations were carried out at a reduced 'experimental' scale rather than full repository scale. The work has shown the possibility to investigate also the changing physical properties of degrading cement. To further develop the model more emphasis is needed on kinetics and the detailed development of a nearly clogged pore space. Modelling of the full repository scale could be another way forward to understand the behaviour of degrading concrete. A general conclusion is that the combined effects of chemical evolution and physical degradation should be analysed in performance assessments of cementitious repositories. Moreover, the project results will be used as one basis in coming reviews of SKB's safety assessments of repositories for spent fuel and low-and intermediate level waste.
Coupled Particle Transport and Pattern Formation in a Nonlinear Leaky-Box Model
Barghouty, A. F.; El-Nemr, K. W.; Baird, J. K.
2009-01-01
Effects of particle-particle coupling on particle characteristics in nonlinear leaky-box type descriptions of the acceleration and transport of energetic particles in space plasmas are examined in the framework of a simple two-particle model based on the Fokker-Planck equation in momentum space. In this model, the two particles are assumed coupled via a common nonlinear source term. In analogy with a prototypical mathematical system of diffusion-driven instability, this work demonstrates that steady-state patterns with strong dependence on the magnetic turbulence but a rather weak one on the coupled particles attributes can emerge in solutions of a nonlinearly coupled leaky-box model. The insight gained from this simple model may be of wider use and significance to nonlinearly coupled leaky-box type descriptions in general.
Radiative corrections to Higgs couplings with weak gauge bosons in custodial multi-Higgs models
Chiang, Cheng-Wei; Kuo, An-Li; Yagyu, Kei
2017-11-01
We calculate 1-loop radiative corrections to the hZZ and hWW couplings in models with next-to-simplest Higgs sectors satisfying the electroweak ρ parameter equal to 1 at tree level: the real Higgs singlet model, the two-Higgs doublet models, and the Georgi-Machacek model. Under theoretical and current experimental constraints, the three models have different correlations between the deviations in the hZZ and hWW couplings from the standard model predictions. In particular, we find for each model predictions with no overlap with the other two models.
Coupled 1D-2D hydrodynamic inundation model for sewer overflow: Influence of modeling parameters
Directory of Open Access Journals (Sweden)
Adeniyi Ganiyu Adeogun
2015-10-01
Full Text Available This paper presents outcome of our investigation on the influence of modeling parameters on 1D-2D hydrodynamic inundation model for sewer overflow, developed through coupling of an existing 1D sewer network model (SWMM and 2D inundation model (BREZO. The 1D-2D hydrodynamic model was developed for the purpose of examining flood incidence due to surcharged water on overland surface. The investigation was carried out by performing sensitivity analysis on the developed model. For the sensitivity analysis, modeling parameters, such as mesh resolution Digital Elevation Model (DEM resolution and roughness were considered. The outcome of the study shows the model is sensitive to changes in these parameters. The performance of the model is significantly influenced, by the Manning's friction value, the DEM resolution and the area of the triangular mesh. Also, changes in the aforementioned modeling parameters influence the Flood characteristics, such as the inundation extent, the flow depth and the velocity across the model domain.
Izquierdo, Germán; Blanquet-Jaramillo, Roberto C.; Sussman, Roberto A.
2018-01-01
The quasi-local scalar variables approach is applied to a spherically symmetric inhomogeneous Lemaître-Tolman-Bondi metric containing a mixture of non-relativistic cold dark matter and coupled dark energy with constant equation of state. The quasi-local coupling term considered is proportional to the quasi-local cold dark matter energy density and a quasi-local Hubble factor-like scalar via a coupling constant α . The autonomous numerical system obtained from the evolution equations is classified for different choices of the free parameters: the adiabatic constant of the dark energy w and α . The presence of a past attractor in a non-physical region of the energy densities phase-space of the system makes the coupling term non physical when the energy flows from the matter to the dark energy in order to avoid negative values of the dark energy density in the past. On the other hand, if the energy flux goes from dark energy to dark matter, the past attractor lies in a physical region. The system is also numerically solved for some interesting initial profiles leading to different configurations: an ever expanding mixture, a scenario where the dark energy is completely consumed by the non-relativistic matter by means of the coupling term, a scenario where the dark energy disappears in the inner layers while the outer layers expand as a mixture of both sources, and, finally, a structure formation toy model scenario, where the inner shells containing the mixture collapse while the outer shells expand.
Improved modelling of atmospheric ammonia over Denmark using the coupled modelling system DAMOS
Directory of Open Access Journals (Sweden)
C. Geels
2012-07-01
Full Text Available A local-scale Gaussian dispersion-deposition model (OML-DEP has been coupled to a regional chemistry-transport model (DEHM with a resolution of approximately 6 km × 6 km over Denmark in the Danish Ammonia Modelling System, DAMOS. Thereby, it has been possible to model the distribution of ammonia concentrations and depositions on a spatial resolution down to 400 m × 400 m for selected areas in Denmark. DAMOS has been validated against measured concentrations from the dense measuring network covering Denmark. Here measured data from 21 sites are included and the validation period covers 2–5 years within the period 2005–2009. A standard time series analysis (using statistic parameters like correlation and bias shows that the coupled model system captures the measured time series better than the regional- scale model alone. However, our study also shows that about 50% of the modelled concentration level at a given location originates from non-local emission sources. The local-scale model covers a domain of 16 km × 16 km, and of the locally released ammonia (NH_{3} within this domain, our simulations at five sites show that 14–27% of the locally (within 16 km × 16 km emitted NH_{3} also deposits locally. These results underline the importance of including both high-resolution local-scale modelling of NH_{3} as well as the regional-scale component described by the regional model. The DAMOS system can be used as a tool in environmental management in relation to assessments of total nitrogen load of sensitive nature areas in intense agricultural regions. However, high spatio-temporal resolution in input parameters like NH_{3} emissions and land-use data is required.
Advanced Modeling of the Electrostatic Field Coupling in Graphene Nanoribbons
Directory of Open Access Journals (Sweden)
Luca Pierantoni
2012-11-01
Full Text Available The field coupling of Graphene NanoRibbons (GNR, which is very important from the view point of realistic configurations / applications such as in field effect transistor, interconnects, plasmonic transmission lines, is analyzed and presented in this communication. We consider the quasi-static response of two GNRs coupled by Coulomb interaction : the Schrödinger equation in the twodimensional (2D domain of the GNRs is solved together with the three dimensional (3D Poisson equation. It is observed that, unless the two GNRs are very close to each other, their Coulomb interaction is not so strong, in the sense that their charge and potential distributions are just slightly distorted by the presence of the other GNR. The effect is even lower in the case of semimetallic GNRs,where the modulation of current and charge by external potential is known to be intrinsically small, owing to the absence of an energy band gap.
Scenario Analysis With Economic-Energy Systems Models Coupled to Simple Climate Models
Hanson, D. A.; Kotamarthi, V. R.; Foster, I. T.; Franklin, M.; Zhu, E.; Patel, D. M.
2008-12-01
Here, we compare two scenarios based on Stanford University's Energy Modeling Forum Study 22 on global cooperative and non-cooperative climate policies. In the former, efficient transition paths are implemented including technology Research and Development effort, energy conservation programs, and price signals for greenhouse gas (GHG) emissions. In the non-cooperative case, some countries try to relax their regulations and be free riders. Total emissions and costs are higher in the non-cooperative scenario. The simulations, including climate impacts, run to the year 2100. We use the Argonne AMIGA-MARS economic-energy systems model, the Texas AM University's Forest and Agricultural Sector Optimization Model (FASOM), and the University of Illinois's Integrated Science Assessment Model (ISAM), with offline coupling between the FASOM and AMIGA-MARS and an online coupling between AMIGA-MARS and ISAM. This set of models captures the interaction of terrestrial systems, land use, crops and forests, climate change, human activity, and energy systems. Our scenario simulations represent dynamic paths over which all the climate, terrestrial, economic, and energy technology equations are solved simultaneously Special attention is paid to biofuels and how they interact with conventional gasoline/diesel fuel markets. Possible low-carbon penetration paths are based on estimated costs for new technologies, including cellulosic biomass, coal-to-liquids, plug-in electric vehicles, solar and nuclear energy. We explicitly explore key uncertainties that affect mitigation and adaptation scenarios.
Modeling the Network Dynamics of Pulse-Coupled Neurons
Chandra, Sarthak; Hathcock, David; Crain, Kimberly; Antonsen, Thomas M.; Girvan, Michelle; Ott, Edward
2017-01-01
We derive a mean-field approximation for the macroscopic dynamics of large networks of pulse-coupled theta neurons in order to study the effects of different network degree distributions, as well as degree correlations (assortativity). Using the ansatz of Ott and Antonsen (Chaos, 19 (2008) 037113), we obtain a reduced system of ordinary differential equations describing the mean-field dynamics, with significantly lower dimensionality compared with the complete set of dynamical equations for t...
Directory of Open Access Journals (Sweden)
Michael J Hull
2015-05-01
Full Text Available Gap junctions between fine unmyelinated axons can electrically couple groups of brain neurons to synchronise ﬁring and contribute to rhythmic activity. To explore the distribution and significance of electrical coupling, we modelled a well analysed, small population of brainstem neurons which drive swimming in young frog tadpoles. A passive network of 30 multicompartmental neurons with unmyelinated axons was used to infer that: axon-axon gap junctions close to the soma gave the best match to experimentally measured coupling coefﬁcients; axon diameter had a strong inﬂuence on coupling; most neurons were coupled indirectly via the axons of other neurons. When active channels were added, gap junctions could make action potential propagation along the thin axons unreliable. Increased sodium and decreased potassium channel densities in the initial axon segment improved action potential propagation. Modelling suggested that the single spike ﬁring to step current injection observed in whole-cell recordings is not a cellular property but a dynamic consequence of shunting resulting from electrical coupling. Without electrical coupling, firing of the population during depolarising current was unsynchronised; with coupling, the population showed synchronous recruitment and rhythmic firing. When activated instead by increasing levels of modelled sensory pathway input, the population without electrical coupling was recruited incrementally to unpatterned activity. However, when coupled, the population was recruited all-or-none at threshold into a rhythmic swimming pattern: the tadpole "decided" to swim. Modelling emphasises uncertainties about fine unmyelinated axon physiology but, when informed by biological data, makes general predictions about gap junctions: locations close to the soma; relatively small numbers; many indirect connections between neurons; cause of action potential propagation failure in fine axons; misleading alteration of intrinsic
Coupled Dynamic Modeling of Floating Wind Turbine Systems: Preprint
Energy Technology Data Exchange (ETDEWEB)
Wayman, E. N.; Sclavounos, P. D.; Butterfield, S.; Jonkman, J.; Musial, W.
2006-03-01
This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offshore wind turbines in water depths of 10-200 m. Methods for the coupled structural, hydrodynamic, and aerodynamic analysis of floating wind turbine systems are presented in the frequency domain. This analysis was conducted by coupling the aerodynamics and structural dynamics code FAST [4] developed at NREL with the wave load and response simulation code WAMIT (Wave Analysis at MIT) [15] developed at MIT. Analysis tools were developed to consider coupled interactions between the wind turbine and the floating system. These include the gyroscopic loads of the wind turbine rotor on the tower and floater, the aerodynamic damping introduced by the wind turbine rotor, the hydrodynamic damping introduced by wave-body interactions, and the hydrodynamic forces caused by wave excitation. Analyses were conducted for two floater concepts coupled with the NREL 5-MW Offshore Baseline wind turbine in water depths of 10-200 m: the MIT/NREL Shallow Drafted Barge (SDB) and the MIT/NREL Tension Leg Platform (TLP). These concepts were chosen to represent two different methods of achieving stability to identify differences in performance and cost of the different stability methods. The static and dynamic analyses of these structures evaluate the systems' responses to wave excitation at a range of frequencies, the systems' natural frequencies, and the standard deviations of the systems' motions in each degree of freedom in various wind and wave environments. This article in various wind and wave environments. This article explores the effects of coupling the wind turbine with the floating platform, the effects of water depth, and the effects of wind speed on the systems' performance. An economic feasibility analysis of
Coupling of the PISCES device modeler to a 3-D Maxwell FDTD solver
Energy Technology Data Exchange (ETDEWEB)
Thomas, V.A.; Jones, M.E.; Mason, R.J. [Los Alamos National Lab., NM (United States)
1995-09-01
The authors show how PISCES-like semiconductor models can be joined non-invasively to finite difference time domain models for the calculation of coupled external electromagnetics. The method involves tricking the standard current boundary condition for the device model into accepting an effective parallel external capacitance. For nearly steady state device conditions the authors show the results for a transmission line-coupled PISCES diode to agree well with those for an ideal diode.
Point-coupling models from mesonic hyper massive limit and mean-field approaches
Energy Technology Data Exchange (ETDEWEB)
Lourenco, O.; Dutra, M., E-mail: odilon@ita.br [Departamento de Fisica, Instituto Tecnologico da Aeronautica - CTA, Sao Jose dos Campos, SP (Brazil); Delfino, Antonio, E-mail: delfino@if.uff.br [Instituto de Fisica, Universidade Federal Fluminense, Niteroi, RJ (Brazil); Amaral, R.L.P.G. [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA (United States)
2012-08-15
t In this work, we show how nonlinear point coupling models, described by a Lagrangian density containing only terms up to fourth order in the fermion condensate ({Psi}-bar{Psi}), are derived from a modified meson exchange nonlinear Walecka model. We present two methods of derivation, namely the hyper massive meson limit within a functional integral approach and the mean-field approximation, in which equations of state at zero temperature of the nonlinear point-coupling models are directly obtained. (author)
Zeng, Jicai; Zha, Yuanyuan; Zhang, Yonggen; Shi, Liangsheng; Zhu, Yan; Yang, Jinzhong
2017-11-01
Multi-scale modeling of the localized groundwater flow problems in a large-scale aquifer has been extensively investigated under the context of cost-benefit controversy. An alternative is to couple the parent and child models with different spatial and temporal scales, which may result in non-trivial sub-model errors in the local areas of interest. Basically, such errors in the child models originate from the deficiency in the coupling methods, as well as from the inadequacy in the spatial and temporal discretizations of the parent and child models. In this study, we investigate the sub-model errors within a generalized one-way coupling scheme given its numerical stability and efficiency, which enables more flexibility in choosing sub-models. To couple the models at different scales, the head solution at parent scale is delivered downward onto the child boundary nodes by means of the spatial and temporal head interpolation approaches. The efficiency of the coupling model is improved either by refining the grid or time step size in the parent and child models, or by carefully locating the sub-model boundary nodes. The temporal truncation errors in the sub-models can be significantly reduced by the adaptive local time-stepping scheme. The generalized one-way coupling scheme is promising to handle the multi-scale groundwater flow problems with complex stresses and heterogeneity.
A Model for Reintegrating Couples and Family Therapy Training in Psychiatric Residency Programs
Rait, Douglas; Glick, Ira
2008-01-01
Objective: The authors propose a family-systems training model for general residency training programs in psychiatry based on the couples and family therapy training program in Stanford's Department of Psychiatry and Behavioral Sciences. Methods: The authors review key elements in couples and family therapy training. Examples are drawn from the…
Modeling of inter-neuronal coupling medium and its impact on neuronal synchronization.
Iqbal, Muhammad; Rehan, Muhammad; Hong, Keum-Shik
2017-01-01
In this paper, modeling of the coupling medium between two neurons, the effects of the model parameters on the synchronization of those neurons, and compensation of coupling strength deficiency in synchronization are studied. Our study exploits the inter-neuronal coupling medium and investigates its intrinsic properties in order to get insight into neuronal-information transmittance and, there from, brain-information processing. A novel electrical model of the coupling medium that represents a well-known RLC circuit attributable to the coupling medium's intrinsic resistive, inductive, and capacitive properties is derived. Surprisingly, the integration of such properties reveals the existence of a natural three-term control strategy, referred to in the literature as the proportional integral derivative (PID) controller, which can be responsible for synchronization between two neurons. Consequently, brain-information processing can rely on a large number of PID controllers based on the coupling medium properties responsible for the coherent behavior of neurons in a neural network. Herein, the effects of the coupling model (or natural PID controller) parameters are studied and, further, a supervisory mechanism is proposed that follows a learning and adaptation policy based on the particle swarm optimization algorithm for compensation of the coupling strength deficiency.
Modeling of inter-neuronal coupling medium and its impact on neuronal synchronization
Iqbal, Muhammad; Hong, Keum-Shik
2017-01-01
In this paper, modeling of the coupling medium between two neurons, the effects of the model parameters on the synchronization of those neurons, and compensation of coupling strength deficiency in synchronization are studied. Our study exploits the inter-neuronal coupling medium and investigates its intrinsic properties in order to get insight into neuronal-information transmittance and, there from, brain-information processing. A novel electrical model of the coupling medium that represents a well-known RLC circuit attributable to the coupling medium’s intrinsic resistive, inductive, and capacitive properties is derived. Surprisingly, the integration of such properties reveals the existence of a natural three-term control strategy, referred to in the literature as the proportional integral derivative (PID) controller, which can be responsible for synchronization between two neurons. Consequently, brain-information processing can rely on a large number of PID controllers based on the coupling medium properties responsible for the coherent behavior of neurons in a neural network. Herein, the effects of the coupling model (or natural PID controller) parameters are studied and, further, a supervisory mechanism is proposed that follows a learning and adaptation policy based on the particle swarm optimization algorithm for compensation of the coupling strength deficiency. PMID:28486505
A Multi-Model Reduction Technique for Optimization of Coupled Structural-Acoustic Problems
DEFF Research Database (Denmark)
Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas
2016-01-01
Finite Element models of structural-acoustic coupled systems can become very large for complex structures with multiple connected parts. Optimization of the performance of the structure based on harmonic analysis of the system requires solving the coupled problem iteratively and for several...
Circumplex Model of Marital Systems: An Empirical Study of Clinic and Nonclinic Couples
Sprenkle, Douglas H.; Olson, David H. L.
1978-01-01
The interaction processes of 25 couples receiving marriage counseling were compared with a control group of 25 couples not receiving counseling. The study was a partial test of a circumplex model of marital and family systems. The major variable was adaptability. Creativity and support were also examined. (Author)
Modelling the Arctic Stable boundary layer and its coupling to the surface
Steeneveld, G.J.; Wiel, van de B.J.H.; Holtslag, A.A.M.
2006-01-01
The impact of coupling the atmosphere to the surface energy balance is examined for the stable boundary layer, as an extension of the first GABLS (GEWEX Atmospheric Boundary-Layer Study) one-dimensional model intercomparison. This coupling is of major importance for the stable boundary-layer
The top right coupling in the aligned two-Higgs-doublet model
Energy Technology Data Exchange (ETDEWEB)
Ayala, Cesar [Departament de Física Teòrica, Universitat de València & Instituto de Física Corpuscular (IFIC),Centro Mixto Universitat de València-CSIC,E-46100 Burjassot, València (Spain); Department of Physics, Universidad Técnica Federico Santa María,Casilla 110-V, Valparaíso (Chile); González-Sprinberg, Gabriel A. [Instituto de Física, Facultad de Ciencias, Universidad de la República,Iguá 4225, Montevideo 11600 (Uruguay); Martinez, R. [Departamento de Física, Universidad Nacional de Colombia,Bogotá Distrito Capital (Colombia); Vidal, Jordi [Departament de Física Teòrica, Universitat de València & Instituto de Física Corpuscular (IFIC),Centro Mixto Universitat de València-CSIC,E-46100 Burjassot, València (Spain)
2017-03-24
We compute the top quark right coupling in the aligned two-Higgs-doublet model. In the Standard Model the real part of this coupling is dominated by QCD-gluon-exchange diagram, but the imaginary part, instead, is purely electroweak at one loop. Within this model we show that values for the imaginary part of the coupling up to one order of magnitude larger than the electroweak prediction can be obtained. For the real part of the electroweak contribution we find that it can be of the order of 2×10{sup −4}. We also present detailed results of the one loop analytical computation.
Synthesis, characterisation and modelling of a ferromagnetically coupled chromium(III) Dimer
DEFF Research Database (Denmark)
Morsing, Thorbjørn Juul; Weihe, Høgni; Bendix, Jesper
2014-01-01
A rare example of a ferromagnetically coupled dinuclear chromium(III) complex, the di-μ-hydroxobis[tetrakis(isothiocyanato)chromate(III)] anion, is reported. This complex has been synthesised from the oxo-bridged acetonitrile complex [(CH3CN)5CrOCr(NCCH3)5](BF4)4 and isolated as the solvated...... reported for a ferromagnetically coupled Cr-diol, and they allow for detailed modelling that encompasses zero-field splittings (ZFS) and fourth-order spin-Hamiltonian parameters for the coupled system. The structural parameters that determine the magnitude and sign of the exchange coupling were studied...
DEFF Research Database (Denmark)
Salimzadeh, Saeed; Paluszny, Adriana; Nick, Hamidreza M.
2018-01-01
A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled to a mec......A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled....... The model has been validated against several analytical solutions, and applied to study the effects of the deformable fractures on the injection of cold water in fractured geothermal systems. Results show that the creation of flow channelling due to the thermal volumetric contraction of the rock matrix...
An Improved Coupling of Numerical and Physical Models for Simulating Wave Propagation
DEFF Research Database (Denmark)
Yang, Zhiwen; Liu, Shu-xue; Li, Jin-xuan
2014-01-01
An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model (FEM) based Boussinesq equations is applied for the numerical wave simulation, and a 2D piston-type wavemaker is used...... for the physical wave generation. An innovative scheme combining fourth-order Lagrange interpolation and Runge-Kutta scheme is described for solving the coupling equation. A Transfer function modulation method is presented to minimize the errors induced from the hydrodynamic invalidity of the coupling model and....../or the mechanical capability of the wavemaker in area where nonlinearities or dispersion predominate. The overall performance and applicability of the coupling model has been experimentally validated by accounting for both regular and irregular waves and varying bathymetry. Experimental results show...
From global circulation to flood loss: Coupling models across the scales
Felder, Guido; Gomez-Navarro, Juan Jose; Bozhinova, Denica; Zischg, Andreas; Raible, Christoph C.; Ole, Roessler; Martius, Olivia; Weingartner, Rolf
2017-04-01
The prediction and the prevention of flood losses requires an extensive understanding of underlying meteorological, hydrological, hydraulic and damage processes. Coupled models help to improve the understanding of such underlying processes and therefore contribute the understanding of flood risk. Using such a modelling approach to determine potentially flood-affected areas and damages requires a complex coupling between several models operating at different spatial and temporal scales. Although the isolated parts of the single modelling components are well established and commonly used in the literature, a full coupling including a mesoscale meteorological model driven by a global circulation one, a hydrologic model, a hydrodynamic model and a flood impact and loss model has not been reported so far. In the present study, we tackle the application of such a coupled model chain in terms of computational resources, scale effects, and model performance. From a technical point of view, results show the general applicability of such a coupled model, as well as good model performance. From a practical point of view, such an approach enables the prediction of flood-induced damages, although some future challenges have been identified.
The phonon-coupling model for Skyrme forces
Lyutorovich, N.; Tselyaev, V.; Speth, J.; Krewald, S.; Reinhard, P.-G.
2016-11-01
A short review on the self-consistent RPA based on the energy-density functional of the Skyrme type is given. We also present an extension of the RPA where the coupling of phonons to the single-particle states is considered. Within this approach we present numerical results which are compared with data. The self-consistent approach is compared with the Landau-Migdal theory. Here we derive from the self-consistent ph interaction, the Landau-Migdal parameters as well as their density dependence. In the Appendix a new derivation of the reduced matrix elements of the ph interaction is presented.
The phonon-coupling model for Skyrme forces
Energy Technology Data Exchange (ETDEWEB)
Lyutorovich, N.; Tselyaev, V. [St. Petersburg State University (Russian Federation); Speth, J., E-mail: J.Speth@fz-juelich.de; Krewald, S. [Forschungszentrum Jülich, Institut für Kernphysik (Germany); Reinhard, P.-G. [Universität Erlangen-Nürnberg, Institut für Theoretische Physik II (Germany)
2016-11-15
A short review on the self-consistent RPA based on the energy-density functional of the Skyrme type is given. We also present an extension of the RPA where the coupling of phonons to the single-particle states is considered. Within this approach we present numerical results which are compared with data. The self-consistent approach is compared with the Landau–Migdal theory. Here we derive from the self-consistent ph interaction, the Landau–Migdal parameters as well as their density dependence. In the Appendix a new derivation of the reduced matrix elements of the ph interaction is presented.
Consensus Formation in Science Modeled by Aggregated Bibliographic Coupling
DEFF Research Database (Denmark)
Nicolaisen, Jeppe; Frandsen, Tove Faber
2012-01-01
Abstract: The level of consensus in science has traditionally been measured by a number of different methods. The variety is important as each method measures different aspects of science and consensus. Citation analytical studies have previously measured the level of consensus using the scientific...... journal as their unit of analysis. To produce a more fine grained citation analysis one needs to study consensus formation on an even more detailed level – i.e. the scientific document or article. To do so, we have developed a new technique that measures consensus by aggregated bibliographic couplings...
The Hintermann-Merlini-Baxter-Wu and the infinite-coupling-limit Ashkin-Teller models
Energy Technology Data Exchange (ETDEWEB)
Huang Yuan, E-mail: huangy22@mail.ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Deng Youjin, E-mail: yjdeng@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jacobsen, Jesper Lykke, E-mail: jacobsen@lpt.ens.fr [Laboratoire de Physique Theorique, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris (France); Salas, Jesus, E-mail: jsalas@math.uc3m.es [Grupo de Modelizacion, Simulacion Numerica y Matematica Industrial, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes (Spain); Grupo de Teorias de Campos y Fisica Estadistica, Instituto Gregorio Millan, Universidad Carlos III de Madrid, Unidad asociada al IEM-CSIC, Madrid (Spain)
2013-03-11
We show how the Hintermann-Merlini-Baxter-Wu model (which is a generalization of the well-known Baxter-Wu model to a general Eulerian triangulation) can be mapped onto a particular infinite-coupling-limit of the Ashkin-Teller model. We work out some mappings among these models, also including the standard and mixed Ashkin-Teller models. Finally, we compute the phase diagram of the infinite-coupling-limit Ashkin-Teller model on the square, triangular, hexagonal, and kagome lattices.
General dynamical properties of cosmological models with nonminimal kinetic coupling
Matsumoto, Jiro; Sushkov, Sergey V.
2018-01-01
We consider cosmological dynamics in the theory of gravity with the scalar field possessing the nonminimal kinetic coupling to curvature given as η Gμνphi,μphi,ν, where η is an arbitrary coupling parameter, and the scalar potential V(phi) which assumed to be as general as possible. With an appropriate dimensionless parametrization we represent the field equations as an autonomous dynamical system which contains ultimately only one arbitrary function χ (x)= 8 π | η | V(x/√8 π) with x=√8 πphi. Then, assuming the rather general properties of χ(x), we analyze stationary points and their stability, as well as all possible asymptotical regimes of the dynamical system. It has been shown that for a broad class of χ(x) there exist attractors representing three accelerated regimes of the Universe evolution, including de Sitter expansion (or late-time inflation), the Little Rip scenario, and the Big Rip scenario. As the specific examples, we consider a power-law potential V(phi)=M4(phi/phi0)σ, Higgs-like potential V(phi)=λ/4(phi2‑phi02)2, and exponential potential V(phi)=M4 e‑phi/phi0.
Analog quantum simulation of the Rabi model in the ultra-strong coupling regime.
Braumüller, Jochen; Marthaler, Michael; Schneider, Andre; Stehli, Alexander; Rotzinger, Hannes; Weides, Martin; Ustinov, Alexey V
2017-10-03
The quantum Rabi model describes the fundamental mechanism of light-matter interaction. It consists of a two-level atom or qubit coupled to a quantized harmonic mode via a transversal interaction. In the weak coupling regime, it reduces to the well-known Jaynes-Cummings model by applying a rotating wave approximation. The rotating wave approximation breaks down in the ultra-strong coupling regime, where the effective coupling strength g is comparable to the energy ω of the bosonic mode, and remarkable features in the system dynamics are revealed. Here we demonstrate an analog quantum simulation of an effective quantum Rabi model in the ultra-strong coupling regime, achieving a relative coupling ratio of g/ω ~ 0.6. The quantum hardware of the simulator is a superconducting circuit embedded in a cQED setup. We observe fast and periodic quantum state collapses and revivals of the initial qubit state, being the most distinct signature of the synthesized model.An analog quantum simulation scheme has been explored with a quantum hardware based on a superconducting circuit. Here the authors investigate the time evolution of the quantum Rabi model at ultra-strong coupling conditions, which is synthesized by slowing down the system dynamics in an effective frame.
Simulating High Flux Isotope Reactor Core Thermal-Hydraulics via Interdimensional Model Coupling
Energy Technology Data Exchange (ETDEWEB)
Travis, Adam R [ORNL
2014-05-01
A coupled interdimensional model is presented for the simulation of the thermal-hydraulic characteristics of the High Flux Isotope Reactor core at Oak Ridge National Laboratory. The model consists of two domains a solid involute fuel plate and the surrounding liquid coolant channel. The fuel plate is modeled explicitly in three-dimensions. The coolant channel is approximated as a twodimensional slice oriented perpendicular to the fuel plate s surface. The two dimensionally-inconsistent domains are linked to one another via interdimensional model coupling mechanisms. The coupled model is presented as a simplified alternative to a fully explicit, fully three-dimensional model. Involute geometries were constructed in SolidWorks. Derivations of the involute construction equations are presented. Geometries were then imported into COMSOL Multiphysics for simulation and modeling. Both models are described in detail so as to highlight their respective attributes in the 3D model, the pursuit of an accurate, reliable, and complete solution; in the coupled model, the intent to simplify the modeling domain as much as possible without affecting significant alterations to the solution. The coupled model was created with the goal of permitting larger portions of the reactor core to be modeled at once without a significant sacrifice to solution integrity. As such, particular care is given to validating incorporated model simplifications. To the greatest extent possible, the decrease in solution time as well as computational cost are quantified versus the effects such gains have on the solution quality. A variant of the coupled model which sufficiently balances these three solution characteristics is presented alongside the more comprehensive 3D model for comparison and validation.
Progress and Challenges in Coupled Hydrodynamic-Ecological Estuarine Modeling
Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational po...
Directory of Open Access Journals (Sweden)
H. W. Ter Maat
2010-08-01
Full Text Available This paper is a case study to investigate what the main controlling factors are that determine atmospheric carbon dioxide content for a region in the centre of The Netherlands. We use the Regional Atmospheric Modelling System (RAMS, coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C, and including also submodels for urban and marine fluxes, which in principle should include the dominant mechanisms and should be able to capture the relevant dynamics of the system. To validate the model, observations are used that were taken during an intensive observational campaign in central Netherlands in summer 2002. These include flux-tower observations and aircraft observations of vertical profiles and spatial fluxes of various variables.
The simulations performed with the coupled regional model (RAMS-SWAPS-C are in good qualitative agreement with the observations. The station validation of the model demonstrates that the incoming shortwave radiation and surface fluxes of water and CO_{2} are well simulated. The comparison against aircraft data shows that the regional meteorology (i.e. wind, temperature is captured well by the model. Comparing spatially explicitly simulated fluxes with aircraft observed fluxes we conclude that in general latent heat fluxes are underestimated by the model compared to the observations but that the latter exhibit large variability within all flights. Sensitivity experiments demonstrate the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same tests also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.
Using Some Coupled Numerical Models in Problems of Designing an Inductive Electrothermal Equipment
Directory of Open Access Journals (Sweden)
LEUCA Teodor
2014-05-01
Full Text Available This paper focuses on the numerical modeling of coupling the electromagnetic and the thermal field, in the process of inductive heating, for inductive electrothermal equipments. Numerical results are carried out by using a FLUX2D application.
Phase models and clustering in networks of oscillators with delayed coupling
Campbell, Sue Ann; Wang, Zhen
2018-01-01
We consider a general model for a network of oscillators with time delayed coupling where the coupling matrix is circulant. We use the theory of weakly coupled oscillators to reduce the system of delay differential equations to a phase model where the time delay enters as a phase shift. We use the phase model to determine model independent existence and stability results for symmetric cluster solutions. Our results extend previous work to systems with time delay and a more general coupling matrix. We show that the presence of the time delay can lead to the coexistence of multiple stable clustering solutions. We apply our analytical results to a network of Morris Lecar neurons and compare these results with numerical continuation and simulation studies.
A coupled hygro-thermo-mechanical model for concrete subjected to variable environmental conditions
National Research Council Canada - National Science Library
Gasch, Tobias; Malm, Richard; Ansell, Anders
2016-01-01
.... Variations of these fields must therefore be included implicitly in an analysis. This paper presents a coupled hygro-thermo-mechanical model for hardened concrete based on the framework of the Microprestress-Solidification theory...
Cloud tuning in a coupled climate model: Impact on 20th century warming
National Research Council Canada - National Science Library
Golaz, Jean‐Christophe; Horowitz, Larry W; Levy, Hiram
2013-01-01
.... A given radiation balance can be achieved by multiple combinations of parameters. We investigate the impact of cloud tuning in the CMIP5 GFDL CM3 coupled climate model by constructing two alternate configurations...
A coupled dynamical-radiational model of stratocumulus
Ye, Weizuo
1990-05-01
A model dealing with interactions between the air and low stratiform clouds is presented based on the mixed-layer model Lilly (1968) pioneered and on Deardorff's three dimensional numerical model results. Its main new aspects lie in 1) consideration of the natures of both the atmosphere and cloud; 2) a new entrainment velocity scheme with few arbitrary assumptions; 3) transition from one-mixed layer to two-mixed layer model; and 4) parameterization of radiation and precipitation calculations. The model results for radiation, moisture, and heat turbulent fluxes turn out to be in good agreement with those calculated or observed by Kawa (1988), Nicholls (1984), and Schmets et al. (1981) in California, the North Sea, and the North Atlantic, respectively. Basically, this paper furnishes the theoretical basis for a model to address questions concerning the time-evolution of thermodynamical profiles both in cloud and out of cloud. The applications of this model wil be in a separate paper.
DEFF Research Database (Denmark)
Butts, Michael; Drews, Martin; Larsen, Morten Andreas Dahl
2014-01-01
To improve our understanding of the impacts of feedback between the atmosphere and the terrestrial water cycle including groundwater and to improve the integration of water resource management modelling for climate adaption we have developed a dynamically coupled climate–hydrological modelling...... system. The OpenMI modelling interface is used to couple a comprehensive hydrological modelling system, MIKE SHE running on personal computers, and a regional climate modelling system, HIRHAM running on a high performance computing platform. The coupled model enables two-way interaction between...... the atmosphere and the groundwater via the land surface and can represent the lateral movement of water in both the surface and subsurface and their interactions, not normally accounted for in climate models. Meso-scale processes are important for climate in general and rainfall in particular. Hydrological...
Van Buren, Kendra L.; Ouisse, Morvan; Cogan, Scott; Sadoulet-Reboul, Emeline; Maxit, Laurent
2017-09-01
In the development of numerical models, uncertainty quantification (UQ) can inform appropriate allocation of computational resources, often resulting in efficient analysis for activities such as model calibration and robust design. UQ can be especially beneficial for numerical models with significant computational expense, such as coupled models, which require several subsystem models to attain the performance of a more complex, inter-connected system. In the coupled model paradigm, UQ can be applied at either the subsystem model level or the coupled model level. When applied at the subsystem level, UQ is applied directly to the physical input parameters, which can be computationally expensive. In contrast, UQ at the coupled level may not be representative of the physical input parameters, but comes at the benefit of being computationally efficient to implement. To be physically meaningful, analysis at the coupled level requires information about how uncertainty is propagated through from the subsystem level. Herein, the proposed strategy is based on simulations performed at the subsystem level to inform a covariance matrix for UQ performed at the coupled level. The approach is applied to a four-subsystem model of mid-frequency vibrations simulated using the Statistical Modal Energy Distribution Analysis, a variant of the Statistical Energy Analysis. The proposed approach is computationally efficient to implement, while simultaneously capturing information from the subsystem level to ensure the analysis is physically meaningful.
Modelling the coupling of flood discharge with glacier flow during jokulhlaups
Kingslake, J.; Ng, F.
2013-01-01
We explore a mathematical model that couples together a thermomechanically evolving subglacial channel, distributed cavity drainage, and basal sliding along a subglacial flood path fed by a jökulhlaup lake. It allows water transfer between channel and cavities and a migrating subglacial water divide or 'seal' to form between floods. Notably, it accounts for full coupling between the lake and subglacial drainage in terms of both discharge and pressure, unlike models that neglect the pressure c...
Modelling the coupling of flood discharge with glacier flow during jökulhlaups
Kingslake, Jonathan; Ng, Felix
2013-01-01
We explore a mathematical model that couples together a thermomechanically evolving subglacial channel, distributed cavity drainage, and basal sliding along a subglacial flood path fed by a jökulhlaup lake. It allows water transfer between channel and cavities and a migrating subglacial water divide or 'seal' to form between floods. Notably, it accounts for full coupling between the lake and subglacial drainage in terms of both discharge and pressure, unlike models that neglect the pressure c...
Host-Pathogen Coupled Networks: Model for Bacillus Anthracis Interaction with Host Macrophages
2015-09-01
AFRL-RH-WP-TR-2015-0070 HOST-PATHOGEN COUPLED NETWORKS: MODEL FOR BACILLUS ANTHRACIS INTERACTION WITH HOST MACROPHAGES Peter J. Robinson C...DATE (DD-MM-YYYY) 30-09-2015 2. REPORT TYPE Final 3. DATES COVERED (From - To) Oct 2012 – Sept. 2015 4. TITLE AND SUBTITLE Host-Pathogen Coupled...Networks: Model for Bacillus anthracis Interaction with Host Macrophages 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER NA 5c. PROGRAM ELEMENT
Zhao, Yuxin; Deng, Xiong; Zhang, Shaoqing; Liu, Zhengyu; Liu, Chang; Vecchi, Gabriel; Han, Guijun; Wu, Xinrong
2017-11-01
Climate signals are the results of interactions of multiple timescale media such as the atmosphere and ocean in the coupled earth system. Coupled data assimilation (CDA) pursues balanced and coherent climate analysis and prediction initialization by incorporating observations from multiple media into a coupled model. In practice, an observational time window (OTW) is usually used to collect measured data for an assimilation cycle to increase observational samples that are sequentially assimilated with their original error scales. Given different timescales of characteristic variability in different media, what are the optimal OTWs for the coupled media so that climate signals can be most accurately recovered by CDA? With a simple coupled model that simulates typical scale interactions in the climate system and twin CDA experiments, we address this issue here. Results show that in each coupled medium, an optimal OTW can provide maximal observational information that best fits the characteristic variability of the medium during the data blending process. Maintaining correct scale interactions, the resulting CDA improves the analysis of climate signals greatly. These simple model results provide a guideline for when the real observations are assimilated into a coupled general circulation model for improving climate analysis and prediction initialization by accurately recovering important characteristic variability such as sub-diurnal in the atmosphere and diurnal in the ocean.
Directory of Open Access Journals (Sweden)
Y. Zhao
2017-11-01
Full Text Available Climate signals are the results of interactions of multiple timescale media such as the atmosphere and ocean in the coupled earth system. Coupled data assimilation (CDA pursues balanced and coherent climate analysis and prediction initialization by incorporating observations from multiple media into a coupled model. In practice, an observational time window (OTW is usually used to collect measured data for an assimilation cycle to increase observational samples that are sequentially assimilated with their original error scales. Given different timescales of characteristic variability in different media, what are the optimal OTWs for the coupled media so that climate signals can be most accurately recovered by CDA? With a simple coupled model that simulates typical scale interactions in the climate system and twin CDA experiments, we address this issue here. Results show that in each coupled medium, an optimal OTW can provide maximal observational information that best fits the characteristic variability of the medium during the data blending process. Maintaining correct scale interactions, the resulting CDA improves the analysis of climate signals greatly. These simple model results provide a guideline for when the real observations are assimilated into a coupled general circulation model for improving climate analysis and prediction initialization by accurately recovering important characteristic variability such as sub-diurnal in the atmosphere and diurnal in the ocean.
Establishment and analysis of coupled dynamic model for dual-mass silicon micro-gyroscope
Wang, Zhanghui; Qiu, Anping; Shi, Qin; Zhang, Taoyuan
2017-12-01
This paper presents a coupled dynamic model for a dual-mass silicon micro-gyroscope (DMSG). It can quantitatively analyze the influence of left-right stiffness difference on the natural frequencies, modal matrix and modal coupling coefficient of the DMSG. The analytic results are verified by using the finite element method (FEM) simulation. The model shows that with the left-right stiffness difference of 1%, the modal coupling coefficient is 12% in the driving direction and 31% in the sensing direction. It also shows that in order to achieve good separation, the stiffness of base beam should be small enough in both the driving and sensing direction.
3D numerical modeling of coupled phenomena in induced processes of heat treatment with malice
Directory of Open Access Journals (Sweden)
Triwong Peeteenut
2008-01-01
Full Text Available This paper describes a multi-method Malice package for three dimension coupled phenomena in induced processes of heat treatment by an algorithm weakly coupled with the Migen package integral method defining the electromagnetic model and the Flux-Expert package finite element method defining the thermal model. The integral method is well suited to inductive systems undergoing sinusoidal excitation at midrange or high frequency. The unknowns of both models are current density, scalar potential and temperature. Joule power in the electromagnetic model is generated by Eddy currents. It becomes the heat source in the thermal model.
Coupled fvGCM-GCE Modeling System, 3D Cloud-Resolving Model and Cloud Library
Tao, Wei-Kuo
2005-01-01
Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud- resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. A seed fund is available at NASA Goddard to build a MMF based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM). A prototype MMF in being developed and production runs will be conducted at the beginning of 2005. In this talk, I will present: (1) A brief review on GCE model and its applications on precipitation processes, ( 2 ) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), (3) A cloud library generated by Goddard MMF, and 3D GCE model, and (4) A brief discussion on the GCE model on developing a global cloud simulator.
Yu, Xiaolin; Zhang, Shaoqing; Lin, Xiaopei; Li, Mingkui
2017-03-01
The uncertainties in values of coupled model parameters are an important source of model bias that causes model climate drift. The values can be calibrated by a parameter estimation procedure that projects observational information onto model parameters. The signal-to-noise ratio of error covariance between the model state and the parameter being estimated directly determines whether the parameter estimation succeeds or not. With a conceptual climate model that couples the stochastic atmosphere and slow-varying ocean, this study examines the sensitivity of state-parameter covariance on the accuracy of estimated model states in different model components of a coupled system. Due to the interaction of multiple timescales, the fast-varying atmosphere with a chaotic nature is the major source of the inaccuracy of estimated state-parameter covariance. Thus, enhancing the estimation accuracy of atmospheric states is very important for the success of coupled model parameter estimation, especially for the parameters in the air-sea interaction processes. The impact of chaotic-to-periodic ratio in state variability on parameter estimation is also discussed. This simple model study provides a guideline when real observations are used to optimize model parameters in a coupled general circulation model for improving climate analysis and predictions.
Image-model coupling: a simple information theoretic perspective for image sequences
Directory of Open Access Journals (Sweden)
N. D. Smith
2009-03-01
Full Text Available Images are widely used to visualise physical processes. Models may be developed which attempt to replicate those processes and their effects. The technique of coupling model output to images, which is here called "image-model coupling", may be used to help understand the underlying physical processes, and better understand the limitations of the models. An information theoretic framework is presented for image-model coupling in the context of communication along a discrete channel. The physical process may be regarded as a transmitter of images and the model as part of a receiver which decodes or recognises those images. Image-model coupling may therefore be interpreted as image recognition. Of interest are physical processes which exhibit "memory". The response of such a system is not only dependent on the current values of driver variables, but also on the recent history of drivers and/or system description. Examples of such systems in geophysics include the ionosphere and Earth's climate. The discrete channel model is used to help derive expressions for matching images and model output, and help analyse the coupling.
Comparing Longitudinal Coupling and Temporal Delay in a Transmission-Line Model of the Cochlea
Homer, Martin; Szalai, Robert; Champneys, Alan; Epp, Bastian
2011-11-01
In this paper we compare and contrast the effects of longitudinal coupling and temporal delay on a fluid-structure transmission-line model of the mammalian cochlea. This work is based on recent reports that, in order to qualitatively explain experimental data, models of the basilar membrane impedance must include an exponential term that represents a time-delayed feedback. There are also models that include, e.g., a spatial feed-forward mechanism, whose solution is often approximated by replacing the feed-forward coupling by an exponential term. We show that there is no direct equivalence between the time-delay and the longitudinal coupling mechanisms, although qualitatively similar results can be achieved, albeit in very different regions of parameter space. An investigation of the steady-state outputs shows that both models can display sharp tuning, but that the time-delay model requires negative damping for such an effect to occur. Conversely, the longitudinal coupling model provides the most promising results with small positive damping. These results are extended by a careful stability analysis. We find that, whereas a small time delay can stabilize an unstable transmission-line model (with negative damping), that the longitudinal coupling model is stable when the damping is positive. The techniques developed in the paper are directed towards a more comprehensive analysis of nonlinear models.
An electromechanical coupling model of a bending vibration type piezoelectric ultrasonic transducer.
Zhang, Qiang; Shi, Shengjun; Chen, Weishan
2016-03-01
An electromechanical coupling model of a bending vibration type piezoelectric ultrasonic transducer is proposed. The transducer is a Langevin type transducer which is composed of an exponential horn, four groups of PZT ceramics and a back beam. The exponential horn can focus the vibration energy, and can enlarge vibration amplitude and velocity efficiently. A bending vibration model of the transducer is first constructed, and subsequently an electromechanical coupling model is constructed based on the vibration model. In order to obtain the most suitable excitation position of the PZT ceramics, the effective electromechanical coupling coefficient is optimized by means of the quadratic interpolation method. When the effective electromechanical coupling coefficient reaches the peak value of 42.59%, the optimal excitation position (L1=22.52 mm) is found. The FEM method and the experimental method are used to validate the developed analytical model. Two groups of the FEM model (the Group A center bolt is not considered, and but the Group B center bolt is considered) are constructed and separately compared with the analytical model and the experimental model. Four prototype transducers around the peak value are fabricated and tested to validate the analytical model. A scanning laser Doppler vibrometer is employed to test the bending vibration shape and resonance frequency. Finally, the electromechanical coupling coefficient is tested indirectly through an impedance analyzer. Comparisons of the analytical results, FEM results and experiment results are presented, and the results show good agreement. Copyright © 2015 Elsevier B.V. All rights reserved.
Image-model coupling: a simple information theoretic perspective for image sequences
Smith, N. D.; Mitchell, C. N.; Budd, C. J.
2009-03-01
Images are widely used to visualise physical processes. Models may be developed which attempt to replicate those processes and their effects. The technique of coupling model output to images, which is here called "image-model coupling", may be used to help understand the underlying physical processes, and better understand the limitations of the models. An information theoretic framework is presented for image-model coupling in the context of communication along a discrete channel. The physical process may be regarded as a transmitter of images and the model as part of a receiver which decodes or recognises those images. Image-model coupling may therefore be interpreted as image recognition. Of interest are physical processes which exhibit "memory". The response of such a system is not only dependent on the current values of driver variables, but also on the recent history of drivers and/or system description. Examples of such systems in geophysics include the ionosphere and Earth's climate. The discrete channel model is used to help derive expressions for matching images and model output, and help analyse the coupling.
Motor simulation via coupled internal models using sequential Monte Carlo
Dindo H; Zambuto D.; Pezzulo G.
2011-01-01
We describe a generative Bayesian model for action understanding in which inverse-forward internal model pairs are considered 'hypotheses' of plausible action goals that are explored in parallel via an approximate inference mechanism based on sequential Monte Carlo methods. The reenactment of internal model pairs can be considered a form of motor simulation, which supports both perceptual prediction and action understanding at the goal level. However, this procedure is generally considered to...
Simulation and visualization of coupled hydrodynamical, chemical and biological models
Directory of Open Access Journals (Sweden)
Dag Slagstad
1997-04-01
Full Text Available This paper briefly describes the principles of hydrodynamical and ecological modelling of marine systems and how model results are presented by use of MATLAB. Two application examples are shown. One refers to modelling and simulation of the carbon vertical transport in the Greenland Sea and the other is a study on the effect of wind pattern for the invasion success of zooplankton from the Norwegian Sea into the North Sea by use of particle tracking.
Modeling neuro-vascular coupling in rat cerebellum
DEFF Research Database (Denmark)
Rasmussen, Tina; Holstein-Rathlou, Niels-Henrik; Lauritzen, Martin
2009-01-01
We investigated the quantitative relation between neuronal activity and blood flow by means of a general parametric mathematical model which described the neuro-vascular system as being dynamic, linear, time-invariant, and subjected to additive noise. The model was constructed from measurements b...
Modelling surface water flood risk using coupled numerical and physical modelling techniques
Green, D. L.; Pattison, I.; Yu, D.
2015-12-01
Surface water (pluvial) flooding occurs due to intense precipitation events where rainfall cannot infiltrate into the sub-surface or drain via storm water systems. The perceived risk appears to have increased in recent years with pluvial flood events seeming more severe and frequent within the UK. Surface water flood risk currently accounts for one third of all UK flood risk, with approximately two million people living in urban areas being at risk of a 1 in 200 year flood event. Surface water flooding research often focuses upon using 1D, 2D or 1D-2D coupled numerical modelling techniques to understand the extent, depth and severity of actual or hypothetical flood scenarios. Although much research has been conducted using numerical modelling, field data available for model calibration and validation is limited due to the complexities associated with data collection in surface water flood conditions. Ultimately, the data which numerical models are based upon is often erroneous and inconclusive. Physical models offer an alternative and innovative environment to collect data within. A controlled, closed system allows independent variables to be altered individually to investigate cause and effect relationships. Despite this, physical modelling approaches are seldom used in surface water flooding research. Scaled laboratory experiments using a 9m2, two-tiered physical model consisting of: (i) a mist nozzle type rainfall simulator able to simulate a range of rainfall intensities similar to those observed within the United Kingdom, and; (ii) a fully interchangeable, scaled plot surface have been conducted to investigate and quantify the influence of factors such as slope, impermeability, building density/configuration and storm dynamics on overland flow and rainfall-runoff patterns within a range of terrestrial surface conditions. Results obtained within the physical modelling environment will be compared with numerical modelling results using FloodMap (Yu & Lane, 2006
Controlled flavour changing neutral couplings in two Higgs Doublet models
Alves, Joao M.; Botella, Francisco J.; Branco, Gustavo C.; Cornet-Gomez, Fernando; Nebot, Miguel
2017-09-01
We propose a class of two Higgs doublet models where there are flavour changing neutral currents (FCNC) at tree level, but under control due to the introduction of a discrete symmetry in the full Lagrangian. It is shown that in this class of models, one can have simultaneously FCNC in the up and down sectors, in contrast to the situation encountered in the renormalisable and minimal flavour violating 2HDM models put forward by Branco et al. (Phys Lett B 380:119, 1996). The intensity of FCNC is analysed and it is shown that in this class of models one can respect all the strong constraints from experiment without unnatural fine-tuning. It is pointed out that the additional sources of flavour and CP violation are such that they can enhance significantly the generation of the Bbaryon asymmetry of the Universe, with respect to the standard model.
Controlled flavour changing neutral couplings in two Higgs Doublet models
Energy Technology Data Exchange (ETDEWEB)
Alves, Joao M.; Branco, Gustavo C.; Nebot, Miguel [Instituto Superior Tecnico (IST), Lisboa Univ., Departamento de Fisica e Centro de Fisica Teorica de Particulas (CFTP), Lisboa (Portugal); Botella, Francisco J.; Cornet-Gomez, Fernando [Universitat de Valencia-CSIC, Departament de Fisica Teorica y IFIC, Burjassot (Spain)
2017-09-15
We propose a class of two Higgs doublet models where there are flavour changing neutral currents (FCNC) at tree level, but under control due to the introduction of a discrete symmetry in the full Lagrangian. It is shown that in this class of models, one can have simultaneously FCNC in the up and down sectors, in contrast to the situation encountered in the renormalisable and minimal flavour violating 2HDM models put forward by Branco et al. (Phys Lett B 380:119, 1996). The intensity of FCNC is analysed and it is shown that in this class of models one can respect all the strong constraints from experiment without unnatural fine-tuning. It is pointed out that the additional sources of flavour and CP violation are such that they can enhance significantly the generation of the Baryon asymmetry of the Universe, with respect to the standard model. (orig.)
Analytical coupled vibroacoustic modeling of membrane-type acoustic metamaterials: Plate model
Chen, Yangyang; Huang, Guoliang; Zhou, Xiaoming; Hu, Gengkai; Sun, Chin-Teh
2014-12-01
By considering the membrane's dissipation, the membrane-type acoustic metamaterial (MAM) has been demonstrated as a super absorber for low-frequency sound. In the paper, a theoretical vibroacoustic plate model is developed to reveal sound energy absorption mechanism within the MAM under a plane normal incidence. Based on the plate model in conjunction with the point matching method, the in-plane strain energy of the membrane due to the resonant and antiresonant motion of the attached masses can be accurately captured by solving the coupled vibroacoustic integrodifferential equation. Therefore, the sound absorption of the MAM is obtained and discussed, which is also in good agreement with the prediction from the finite element method. In particular, microstructure effects including eccentricity of the attached masses, the depth, thickness and loss factor of the membrane on sound absorption peak values are quantitatively investigated.
Coupled Photochemical and Condensation Model for the Venus Atmosphere
Bierson, Carver; Zhang, Xi; Mendonca, Joao; Liang, Mao-Chang
2017-10-01
Ground based and Venus Express observations have provided a wealth of information on the vertical and latitudinal distribution of many chemical species in the Venus atmosphere [1,2]. Previous 1D models have focused on the chemistry of either the lower [3] or middle atmosphere [4,5]. Photochemical models focusing on the sulfur gas chemistry have also been independent from models of the sulfuric acid haze and cloud formation [6,7]. In recent years sulfur-bearing particles have become important candidates for the observed SO2 inversion above 80 km [5]. To test this hypothesis it is import to create a self-consistent model that includes photochemistry, transport, and cloud condensation.In this work we extend the domain of the 1D chemistry model of Zhang et al. (2012) [5] to encompass the region between the surface to 110 km. This model includes a simple sulfuric acid condensation scheme with gravitational settling. It simultaneously solves for the chemistry and condensation allowing for self-consistent cloud formation. We compare the resulting chemical distributions to observations at all altitudes. We have also validated our model cloud mass against pioneer Venus observations [8]. This updated full atmosphere chemistry model is also being applied in our 2D solver (altitude and altitude). With this 2D model we can model how the latitudinal distribution of chemical species depends on the meridional circulation. This allows us to use the existing chemical observations to place constraints on Venus GCMs [9-11].References: [1] Arney et al., JGR:Planets, 2014 [2] Vandaele et al., Icarus 2017 (pt. 1 & 2) [3] Krasnopolsky, Icarus, 2007 [4] Krasnopolsky, Icarus, 2012 [5] Zhang et al., Icarus 2012 [6] Gao et al., Icarus, 2014 [7] Krasnopolsky, Icarus, 2015 [8] Knollenberg and Hunten, JGR:Space Physics, 1980 [9] Lee et al., JGR:Planets, 2007 [10] Lebonnois et al., Towards Understanding the Climate of Venus, 2013 [11] Mendoncca and Read, Planetary and Space Science, 2016
Directory of Open Access Journals (Sweden)
Kyle G. Horn
2012-01-01
Full Text Available Most models of central pattern generators (CPGs involve two distinct nuclei mutually inhibiting one another via synapses. Here, we present a single-nucleus model of biologically realistic Hodgkin-Huxley neurons with random gap junction coupling. Despite no explicit division of neurons into two groups, we observe a spontaneous division of neurons into two distinct firing groups. In addition, we also demonstrate this phenomenon in a simplified version of the model, highlighting the importance of afterhyperpolarization currents ( to CPGs utilizing gap junction coupling. The properties of these CPGs also appear sensitive to gap junction conductance, probability of gap junction coupling between cells, topology of gap junction coupling, and, to a lesser extent, input current into our simulated nucleus.
Improved modeling of photoluminescent and electroluminescent coupling in multijunction solar cells
Energy Technology Data Exchange (ETDEWEB)
Lan, Dongchen; Geisz, John F.; Steiner, Myles A.; Garcia, Ivan; Friedman, Daniel J.; Green, Martin A.
2015-12-01
The performance of tandem stacks of Group III-V multijunction solar cells continues to improve rapidly, both through improved performance of the individual cells in the stack and through increase in the number of stacked cells. As the radiative efficiency of these individual cells increases, radiative coupling between the stacked cells becomes an increasingly important factor not only in cell design, but also in accurate efficiency measurement and in determining performance of cells and systems under varying spectral conditions in the field. Past modeling has concentrated on electroluminescent coupling between the cells, although photoluminescent coupling is shown to be important for cells operating near their maximum power point voltage or below or when junction defect recombination is significant. Extension of earlier models is proposed to allow this non-negligible component of luminescent coupling to be included. The refined model is validated by measurement of the closely related external emission from both single and double junction cells.
Numerical modeling of coupled water flow and heat transport in soil and snow
Thijs J. Kelleners; Jeremy Koonce; Rose Shillito; Jelle Dijkema; Markus Berli; Michael H. Young; John M. Frank; William Massman
2016-01-01
A one-dimensional vertical numerical model for coupled water flow and heat transport in soil and snow was modified to include all three phases of water: vapor, liquid, and ice. The top boundary condition in the model is driven by incoming precipitation and the surface energy balance. The model was applied to three different terrestrial systems: A warm desert bare...
Coupled two-dimensional edge plasma and neutral gas modeling of tokamak scrape-off-layers
Energy Technology Data Exchange (ETDEWEB)
Maingi, Rajesh [North Carolina State Univ., Raleigh, NC (United States)
1992-08-01
The objective of this study is to devise a detailed description of the tokamak scrape-off-layer (SOL), which includes the best available models of both the plasma and neutral species and the strong coupling between the two in many SOL regimes. A good estimate of both particle flux and heat flux profiles at the limiter/divertor target plates is desired. Peak heat flux is one of the limiting factors in determining the survival probability of plasma-facing-components at high power levels. Plate particle flux affects the neutral flux to the pump, which determines the particle exhaust rate. A technique which couples a two-dimensional (2-D) plasma and a 2-D neutral transport code has been developed (coupled code technique), but this procedure requires large amounts of computer time. Relevant physics has been added to an existing two-neutral-species model which takes the SOL plasma/neutral coupling into account in a simple manner (molecular physics model), and this model is compared with the coupled code technique mentioned above. The molecular physics model is benchmarked against experimental data from a divertor tokamak (DIII-D), and a similar model (single-species model) is benchmarked against data from a pump-limiter tokamak (Tore Supra). The models are then used to examine two key issues: free-streaming-limits (ion energy conduction and momentum flux) and the effects of the non-orthogonal geometry of magnetic flux surfaces and target plates on edge plasma parameter profiles.
Modeling Coupled Evaporation and Seepage in Ventilated Cavities
Energy Technology Data Exchange (ETDEWEB)
T. Ghezzehei; R. Trautz; S. Finsterle; P. Cook; C. Ahlers
2004-07-01
Cavities excavated in unsaturated geological formations are important to activities such as nuclear waste disposal and mining. Such cavities provide a unique setting for simultaneous occurrence of seepage and evaporation. Previously, inverse numerical modeling of field liquid-release tests and associated seepage into cavities were used to provide seepage-related large-scale formation properties by ignoring the impact of evaporation. The applicability of such models was limited to the narrow range of ventilation conditions under which the models were calibrated. The objective of this study was to alleviate this limitation by incorporating evaporation into the seepage models. We modeled evaporation as an isothermal vapor diffusion process. The semi-physical model accounts for the relative humidity, temperature, and ventilation conditions of the cavities. The evaporation boundary layer thickness (BLT) over which diffusion occurs was estimated by calibration against free-water evaporation data collected inside the experimental cavities. The estimated values of BLT were 5 to 7 mm for the open underground drifts and 20 mm for niches closed off by bulkheads. Compared to previous models that neglected the effect of evaporation, this new approach showed significant improvement in capturing seepage fluctuations into open cavities of low relative humidity. At high relative-humidity values (greater than 85%), the effect of evaporation on seepage was very small.
Shin, Sun-Hee; Kim, Ok-Yeon; Kim, Dongmin; Lee, Myong-In
2017-07-01
Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850-2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006-2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about -0.99% K-1 and net radiative warming of 0.46 W m-2 K-1, suggesting a role of positive feedback to global warming.
Synchronization scenarios in the Winfree model of coupled oscillators
Gallego, Rafael; Montbrió, Ernest; Pazó, Diego
2017-10-01
Fifty years ago Arthur Winfree proposed a deeply influential mean-field model for the collective synchronization of large populations of phase oscillators. Here we provide a detailed analysis of the model for some special, analytically tractable cases. Adopting the thermodynamic limit, we derive an ordinary differential equation that exactly describes the temporal evolution of the macroscopic variables in the Ott-Antonsen invariant manifold. The low-dimensional model is then thoroughly investigated for a variety of pulse types and sinusoidal phase response curves (PRCs). Two structurally different synchronization scenarios are found, which are linked via the mutation of a Bogdanov-Takens point. From our results, we infer a general rule of thumb relating pulse shape and PRC offset with each scenario. Finally, we compare the exact synchronization threshold with the prediction of the averaging approximation given by the Kuramoto-Sakaguchi model. At the leading order, the discrepancy appears to behave as an odd function of the PRC offset.
Prototype of a Coupled Mesoscale-Microscale Modeling System
National Research Council Canada - National Science Library
Luces, Saba A; Cionco, Ronald M
2006-01-01
.... A step-wise approach was employed to develop a modular prototype that would first show improved winds using high-resolution diagnostic models, but then be capable of interchanging various components...
An Arctic Ice/Ocean Coupled Model with Wave Interactions
2015-09-30
New Zealand phone: +64 (3) 479-8303 email: vernon.squire@otago.ac.nz Award Number: N00014-131-0279 http://www.maths.otago.ac.nz/∼vsquire LONG...Symposium on Ice, Singapore, August 2014. Squire, V. A. Perspectives of ocean wave / sea ice connectivity relating to climate change and modelling...contemporary Arctic climate models. OBJECTIVES To make progress with our long-term goals, over the lifetime of the project we will – further our
Double-temperature ratchet model and current reversal of coupled Brownian motors
Li, Chen-Pu; Chen, Hong-Bin; Zheng, Zhi-Gang
2017-12-01
On the basis of the transport features and experimental phenomena observed in studies of molecular motors, we propose a double-temperature ratchet model of coupled motors to reveal the dynamical mechanism of cooperative transport of motors with two heads, where the interactions and asynchrony between two motor heads are taken into account. We investigate the collective unidirectional transport of coupled system and find that the direction of motion can be reversed under certain conditions. Reverse motion can be achieved by modulating the coupling strength, coupling free length, and asymmetric coefficient of the periodic potential, which is understood in terms of the effective potential theory. The dependence of the directed current on various parameters is studied systematically. Directed transport of coupled Brownian motors can be manipulated and optimized by adjusting the pulsation period or the phase shift of the pulsation temperature.
On the potentialities of 3D-1D coupled models in hemodynamics simulations.
Blanco, P J; Pivello, M R; Urquiza, S A; Feijóo, R A
2009-05-11
This work comprises a step towards the quantitative and qualitative analysis of coupled local and global hemodynamics phenomena in the arterial system. The aim of this work is to present some numerical examples to put in evidence the importance of the use of 3D-1D coupled models in hemodynamics problems when carrying out simulations of rather complex situations. Accordingly, some cases for which classical modeling cannot be applied are identified and solved. The results obtained here allow us to assess some interrelations between local pointwise quantities (defined at the level of the 3D model) and global mean quantities (defined at the level of the 1D model).
Coupled Model of Artificial Neural Network and Grey Model for Tendency Prediction of Labor Turnover
Directory of Open Access Journals (Sweden)
Yueru Ma
2014-01-01
Full Text Available The tendency of labor turnover in the Chinese enterprise shows the characteristics of seasonal fluctuations and irregular distribution of various factors, especially the Chinese traditional social and cultural characteristics. In this paper, we present a coupled model for the tendency prediction of labor turnover. In the model, a time series of tendency prediction of labor turnover was expressed as trend item and its random item. Trend item of tendency prediction of labor turnover is predicted using Grey theory. Random item of trend item is calculated by artificial neural network model (ANN. A case study is presented by the data of 24 months in a Chinese matured enterprise. The model uses the advantages of “accumulative generation” of a Grey prediction method, which weakens the original sequence of random disturbance factors and increases the regularity of data. It also takes full advantage of the ANN model approximation performance, which has a capacity to solve economic problems rapidly, describes the nonlinear relationship easily, and avoids the defects of Grey theory.
A poroelastic model coupled to a fluid network with applications in lung modelling.
Berger, Lorenz; Bordas, Rafel; Burrowes, Kelly; Grau, Vicente; Tavener, Simon; Kay, David
2016-01-01
We develop a lung ventilation model based on a continuum poroelastic representation of lung parenchyma that is strongly coupled to a pipe network representation of the airway tree. The continuous system of equations is discretized using a low-order stabilised finite element method. The framework is applied to a realistic lung anatomical model derived from computed tomography data and an artificially generated airway tree to model the conducting airway region. Numerical simulations produce physiologically realistic solutions and demonstrate the effect of airway constriction and reduced tissue elasticity on ventilation, tissue stress and alveolar pressure distribution. The key advantage of the model is the ability to provide insight into the mutual dependence between ventilation and deformation. This is essential when studying lung diseases, such as chronic obstructive pulmonary disease and pulmonary fibrosis. Thus the model can be used to form a better understanding of integrated lung mechanics in both the healthy and diseased states. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
Effective Hamiltonian of the nonrigid methanol CH{sub 3}OH molecule in the ground vibronic state
Energy Technology Data Exchange (ETDEWEB)
Burenin, A.V. [Institute of Applied Physics, Nizhnii Novgorod, (Russian Federation)
1995-11-01
For the nonrigid methanol CH{sub 3}OH molecule in the ground vibronic state, the simplest expression for the effective Hamiltonian and generators of its transformation to a reduced form is considered in an arbitrary order of perturbation theroy as a Taylor series expansion in dynamic variables on the basis of the concept of the configuration spin. Partitioning of the configuration-rotational wave functions is given according to the irreducible representations of the rotational subgroup of the symmetry group for the stationary state problem of the molecule considered in the Born-Oppenheimer approximation. 9 refs., 1 tab.
Clementi, Emanuela; Oddo, Paolo; Drudi, Massimiliano; Pinardi, Nadia; Korres, Gerasimos; Grandi, Alessandro
2017-10-01
This work describes the first step towards a fully coupled modelling system composed of an ocean circulation and a wind wave model. Sensitivity experiments are presented for the Mediterranean Sea where the hydrodynamic model NEMO is coupled with the third-generation wave model WaveWatchIII (WW3). Both models are implemented at 1/16° horizontal resolution and are forced by ECMWF 1/4° horizontal resolution atmospheric fields. The models are two-way coupled at hourly intervals exchanging the following fields: sea surface currents and temperature are transferred from NEMO to WW3 by modifying the mean momentum transfer of waves and the wind speed stability parameter, respectively. The neutral drag coefficient computed by WW3 is then passed to NEMO, which computes the surface stress. Five-year (2009-2013) numerical experiments were carried out in both uncoupled and coupled mode. In order to validate the modelling system, numerical results were compared with coastal and drifting buoys and remote sensing data. The results show that the coupling of currents with waves improves the representation of the wave spectrum. However, the wave-induced drag coefficient shows only minor improvements in NEMO circulation fields, such as temperature, salinity, and currents.
Sensitivity of simulated regional Arctic climate to the choice of coupled model domain
Directory of Open Access Journals (Sweden)
Dmitry V. Sein
2014-07-01
Full Text Available The climate over the Arctic has undergone changes in recent decades. In order to evaluate the coupled response of the Arctic system to external and internal forcing, our study focuses on the estimation of regional climate variability and its dependence on large-scale atmospheric and regional ocean circulations. A global ocean–sea ice model with regionally high horizontal resolution is coupled to an atmospheric regional model and global terrestrial hydrology model. This way of coupling divides the global ocean model setup into two different domains: one coupled, where the ocean and the atmosphere are interacting, and one uncoupled, where the ocean model is driven by prescribed atmospheric forcing and runs in a so-called stand-alone mode. Therefore, selecting a specific area for the regional atmosphere implies that the ocean–atmosphere system can develop ‘freely’ in that area, whereas for the rest of the global ocean, the circulation is driven by prescribed atmospheric forcing without any feedbacks. Five different coupled setups are chosen for ensemble simulations. The choice of the coupled domains was done to estimate the influences of the Subtropical Atlantic, Eurasian and North Pacific regions on northern North Atlantic and Arctic climate. Our simulations show that the regional coupled ocean–atmosphere model is sensitive to the choice of the modelled area. The different model configurations reproduce differently both the mean climate and its variability. Only two out of five model setups were able to reproduce the Arctic climate as observed under recent climate conditions (ERA-40 Reanalysis. Evidence is found that the main source of uncertainty for Arctic climate variability and its predictability is the North Pacific. The prescription of North Pacific conditions in the regional model leads to significant correlation with observations, even if the whole North Atlantic is within the coupled model domain. However, the inclusion of the
A flexible method to model HIV serodiscordance among couples in Mozambique.
Directory of Open Access Journals (Sweden)
Adelino J C Juga
Full Text Available Whereas the number of people newly infected by HIV is continuing to decline globally, the epidemic continues to expand in many parts of the world. As the HIV/AIDS epidemic has matured in many countries, it is believed that the proportion of new infections occurring within couples has risen. Across countries, including Mozambique, a sizeable proportion of couples with HIV infection are discordant. A serodiscordant couple is a couple in which one partner has tested positive for HIV and the other has not. To describe the HIV serodiscordance among couples, a variety of association measures can be used. In this paper, we propose the serodiscordance measure (SDM as a new alternative measure. Focus is on the specification of flexible marginal and random effects models for multivariate correlated binary data together with a full-likelihood estimation method, to adequately and directly describe the measure of interest. Fitting joint models allows examining the effects of different risk factors and other covariates on the probability to be HIV positive for each member within a couple, and estimating common effects for both probabilities more efficiently, while accounting for the association between their infection status. Moreover, the interpretation of the proposed association parameter SDM is more direct and relevant and effects of covariates can be studied as well. Results show that the HIV prevalence for the province where a couple was located as well as the union number for the woman within a couple are factors associated with HIV serodiscordance. These findings are important for the Mozambican public health policy makers to design national prevention plans, which include policies to stimulate regular HIV testing for couples as well as adolescents and young adults, prior to getting married or living together as a couple.
Evaluating the Carbon Cycle of a Coupled Atmosphere-Biosphere Model
Energy Technology Data Exchange (ETDEWEB)
Delire, C; Foley, J A; Thompson, S
2002-08-21
We investigate how well a coupled biosphere-atmosphere model, CCM3-IBIS, can simulate the functioning of the terrestrial biosphere and the carbon cycling through it. The simulated climate is compared to observations, while the vegetation cover and the carbon cycle are compared to an offline version of the biosphere model IBIS forced with observed climatic variables. The simulated climate presents some local biases that strongly affect the vegetation (e.g., a misrepresentation of the African monsoon). Compared to the offline model, the coupled model simulates well the globally averaged carbon fluxes and vegetation pools. The zonal mean carbon fluxes and the zonal mean seasonal cycle are also well represented except between 0{sup o} and 20{sup o}N due to the misrepresentation of the African monsoon. These results suggest that, despite regional biases in climate and ecosystem simulations, this coupled atmosphere-biosphere model can be used to explore geographic and temporal variations in the global carbon cycle.
Kaneko, D.
2016-12-01
through seasonal advection thermal effects on potential evaporation by winds blowing eastward over California, the Grand Canyon, Monument Valley, and into the Great Plains. These coupled SST photosynthesis models constitute an advanced approach for crop modeling in the era of recent new climate.
Cosmological implications of Nambu-Jona-Lasinio model with a dynamical coupling
Quintanar, G. Leonardo; de La Macorra, Axel
We study the cosmological implications of the Nambu-Jona-Lasinio (NJL) model when the coupling constant is field dependent. The NJL model has a four-fermion interaction describing two different phases due to quantum interaction effects and determined by the strength of the coupling constant g. It describes massless fermions for weak coupling and a massive fermions and strong coupling, where a fermion condensate is formed. In the original NJL model, the coupling constant g is indeed constant, and in this work we consider a modified version of the NJL model by introducing a dynamical field dependent coupling motivated by string theory. The effective potential as a function of the varying coupling (aimed to implement a natural phase transition) is seen to develop a negative divergence, i.e. becomes a “bottomless well” in certain limit region. Although we explain how an lower unbounded potential is not necessarily unacceptable in a cosmological context, the divergence can be removed if we consider a mass term for the coupling like field. We found that for a proper set of parameters, the total potential obtained has two minima, one located at the origin (the trivial solution, in which the fluid associated with the fields behave like matter); and the other related to the nontrivial solution. This last solution has three possibilities: (1) if the minimum is positive Vmin > 0, the system behaves as a cosmological constant, thus leading eventually to an accelerated universe; (2) if the minimized potential vanishes Vmin = 0, then we have matter with no acceleration; (3) finally a negative minimum Vmin universe with a flat geometry. Therefore, a possible interpretation as dark matter (DM) or dark energy (DE) is allowed among the behaviors implicated in the model.
Soudackov, Alexander V; Hazra, Anirban; Hammes-Schiffer, Sharon
2011-10-14
A theoretical approach for the multidimensional treatment of photoinduced proton-coupled electron transfer (PCET) processes in solution is presented. This methodology is based on the multistate continuum theory with an arbitrary number of diabatic electronic states representing the relevant charge distributions in a general PCET system. The active electrons and transferring proton(s) are treated quantum mechanically, and the electron-proton vibronic free energy surfaces are represented as functions of multiple scalar solvent coordinates corresponding to the single electron and proton transfer reactions involved in the PCET process. A dynamical formulation of the dielectric continuum theory is used to derive a set of coupled generalized Langevin equations of motion describing the time evolution of these collective solvent coordinates. The parameters in the Langevin equations depend on the solvent properties, such as the dielectric constants, relaxation time, and molecular moment of inertia, as well as the solute properties. The dynamics of selected intramolecular nuclear coordinates, such as the proton donor-acceptor distance or a torsional angle within the PCET complex, may also be included in this formulation. A surface hopping method in conjunction with the Langevin equations of motion is used to simulate the nonadiabatic dynamics on the multidimensional electron-proton vibronic free energy surfaces following photoexcitation. This theoretical treatment enables the description of both sequential and concerted mechanisms, as well as more complex processes involving a combination of these mechanisms. The application of this methodology to a series of model systems corresponding to collinear and orthogonal PCET illustrates fundamental aspects of these different mechanisms and elucidates the significance of proton vibrational relaxation and nonequilibrium solvent dynamics. © 2011 American Institute of Physics
Analytical models for coupling reliability in identical two-magnet systems during slow reversals
Kani, Nickvash; Naeemi, Azad
2017-12-01
This paper follows previous works which investigated the strength of dipolar coupling in two-magnet systems. While those works focused on qualitative analyses, this manuscript elucidates reversal through dipolar coupling culminating in analytical expressions for reversal reliability in identical two-magnet systems. The dipolar field generated by a mono-domain magnetic body can be represented by a tensor containing both longitudinal and perpendicular field components; this field changes orientation and magnitude based on the magnetization of neighboring nanomagnets. While the dipolar field does reduce to its longitudinal component at short time-scales, for slow magnetization reversals, the simple longitudinal field representation greatly underestimates the scope of parameters that ensure reliable coupling. For the first time, analytical models that map the geometric and material parameters required for reliable coupling in two-magnet systems are developed. It is shown that in biaxial nanomagnets, the x ̂ and y ̂ components of the dipolar field contribute to the coupling, while all three dimensions contribute to the coupling between a pair of uniaxial magnets. Additionally, the ratio of the longitudinal and perpendicular components of the dipolar field is also very important. If the perpendicular components in the dipolar tensor are too large, the nanomagnet pair may come to rest in an undesirable meta-stable state away from the free axis. The analytical models formulated in this manuscript map the minimum and maximum parameters for reliable coupling. Using these models, it is shown that there is a very small range of material parameters which can facilitate reliable coupling between perpendicular-magnetic-anisotropy nanomagnets; hence, in-plane nanomagnets are more suitable for coupled systems.
Ocean-Atmosphere Coupled Model Simulations of Precipitation in the Central Andes
Nicholls, Stephen D.; Mohr, Karen I.
2015-01-01
The meridional extent and complex orography of the South American continent contributes to a wide diversity of climate regimes ranging from hyper-arid deserts to tropical rainforests to sub-polar highland regions. In addition, South American meteorology and climate are also made further complicated by ENSO, a powerful coupled ocean-atmosphere phenomenon. Modelling studies in this region have typically resorted to either atmospheric mesoscale or atmosphere-ocean coupled global climate models. The latter offers full physics and high spatial resolution, but it is computationally inefficient typically lack an interactive ocean, whereas the former offers high computational efficiency and ocean-atmosphere coupling, but it lacks adequate spatial and temporal resolution to adequate resolve the complex orography and explicitly simulate precipitation. Explicit simulation of precipitation is vital in the Central Andes where rainfall rates are light (0.5-5 mm hr-1), there is strong seasonality, and most precipitation is associated with weak mesoscale-organized convection. Recent increases in both computational power and model development have led to the advent of coupled ocean-atmosphere mesoscale models for both weather and climate study applications. These modelling systems, while computationally expensive, include two-way ocean-atmosphere coupling, high resolution, and explicit simulation of precipitation. In this study, we use the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST), a fully-coupled mesoscale atmosphere-ocean modeling system. Previous work has shown COAWST to reasonably simulate the entire 2003-2004 wet season (Dec-Feb) as validated against both satellite and model analysis data when ECMWF interim analysis data were used for boundary conditions on a 27-9-km grid configuration (Outer grid extent: 60.4S to 17.7N and 118.6W to 17.4W).
Coupled modelling of subsurface water flux for an integrated flood risk management
Directory of Open Access Journals (Sweden)
T. Sommer
2009-07-01
Full Text Available Flood events cause significant damage not only on the surface but also underground. Infiltration of surface water into soil, flooding through the urban sewer system and, in consequence, rising groundwater are the main causes of subsurface damage. The modelling of flooding events is an important part of flood risk assessment. The processes of subsurface discharge of infiltrated water necessitate coupled modelling tools of both, surface and subsurface water fluxes. Therefore, codes for surface flooding, for discharge in the sewerage system and for groundwater flow were coupled with each other. A coupling software was used to amalgamate the individual programs in terms of mapping between the different model geometries, time synchronization and data exchange. The coupling of the models was realized on two scales in the Saxon capital of Dresden (Germany. As a result of the coupled modelling it could be shown that surface flooding dominates processes of any flood event. Compared to flood simulations without coupled modelling no substantial changes of the surface inundation area could be determined. Regarding sewerage, the comparison between the influx of groundwater into sewerage and the loading due to infiltration by flood water showed infiltration of surface flood water to be the main reason for sewerage overloading. Concurrent rainfalls can intensify the problem. The infiltration of the sewerage system by rising groundwater contributes only marginally to the loading of the sewerage and the distribution of water by sewerage has only local impacts on groundwater rise. However, the localization of risk areas due to rising groundwater requires the consideration of all components of the subsurface water fluxes. The coupled modelling has shown that high groundwater levels are the result of a multi-causal process that occurs before and during the flood event.
Predictability of the Indian Ocean Dipole in the coupled models
Liu, Huafeng; Tang, Youmin; Chen, Dake; Lian, Tao
2017-03-01
In this study, the Indian Ocean Dipole (IOD) predictability, measured by the Indian Dipole Mode Index (DMI), is comprehensively examined at the seasonal time scale, including its actual prediction skill and potential predictability, using the ENSEMBLES multiple model ensembles and the recently developed information-based theoretical framework of predictability. It was found that all model predictions have useful skill, which is normally defined by the anomaly correlation coefficient larger than 0.5, only at around 2-3 month leads. This is mainly because there are more false alarms in predictions as leading time increases. The DMI predictability has significant seasonal variation, and the predictions whose target seasons are boreal summer (JJA) and autumn (SON) are more reliable than that for other seasons. All of models fail to predict the IOD onset before May and suffer from the winter (DJF) predictability barrier. The potential predictability study indicates that, with the model development and initialization improvement, the prediction of IOD onset is likely to be improved but the winter barrier cannot be overcome. The IOD predictability also has decadal variation, with a high skill during the 1960s and the early 1990s, and a low skill during the early 1970s and early 1980s, which is very consistent with the potential predictability. The main factors controlling the IOD predictability, including its seasonal and decadal variations, are also analyzed in this study.
Non-generic couplings in supersymmetric standard models
Directory of Open Access Journals (Sweden)
Evgeny I. Buchbinder
2015-09-01
Full Text Available We study two phases of a heterotic standard model, obtained from a Calabi–Yau compactification of the E8×E8 heterotic string, in the context of the associated four-dimensional effective theories. In the first phase we have a standard model gauge group, an MSSM spectrum, four additional U(1 symmetries and singlet fields. In the second phase, obtained from the first by continuing along the singlet directions, three of the additional U(1 symmetries are spontaneously broken and the remaining one is a B–L symmetry. In this second phase, dimension five operators inducing proton decay are consistent with all symmetries and as such, they are expected to be present. We show that, contrary to this expectation, these operators are forbidden due to the additional U(1 symmetries present in the first phase of the model. We emphasise that such “unexpected” absences of operators, due to symmetry enhancement at specific loci in the moduli space, can be phenomenologically relevant and, in the present case, protect the model from fast proton decay.
Complex Automata: Multi-scale Modeling with Coupled Cellular Automata
Hoekstra, A.G.; Caiazzo, A.; Lorenz, E.; Falcone, J.-L.; Chopard, B.; Hoekstra, A.G.; Kroc, J.; Sloot, P.M.A.
2010-01-01
Cellular Automata (CA) are generally acknowledged to be a powerful way to describe and model natural phenomena [1-3]. There are even tempting claims that nature itself is one big (quantum) information processing system, e.g. [4], and that CA may actually be nature’s way to do this processing [5-7].
Model Coupling in Resource Economics: Conditions for Effective Interdisciplinary Collaboration
MacLeod, Miles Alexander James; Nagatsu, Michiru
2016-01-01
In this article we argue for the importance of studying interdisciplinary collaborations by focusing on the role that good choice and design of model-building frameworks and strategies can play overcoming the inherent difficulties of collaborative research. We provide an empirical study of
A product-model supporting coupling's management during microproduct design
DEFF Research Database (Denmark)
Museau, Matthieu; De Grave, Arnaud; Masclet, Cedric
2009-01-01
to represent microproducts during the design flow, taking into account their specificities and exceeding the limits of product representation in actual design tools. The genericity of this model is demonstrated by the instantiation of a micro electro mechanical system (MEMS) radio frequency (RF) switch....
Campione, Salvatore; Klem, John F; Sinclair, Michael B; Brener, Igal; Capolino, Filippo
2014-01-01
Strong light-matter coupling has recently been demonstrated in sub-wavelength volumes by coupling engineered optical transitions in semiconductor heterostructures (e.g., quantum wells) to metasurface resonances via near fields. It has also been shown that different resonator shapes may lead to different Rabi splittings, though this has not yet been well explained. In this paper, our aim is to understand the correlation between resonator shape and Rabi splitting, and in particular determine and quantify the physical parameters that affect strong coupling by developing an equivalent circuit network model whose elements describe energy and dissipation. Because of the subwavelength dimension of each metasurface element, we resort to the quasi-static (electrostatic) description of the near-field and hence define an equivalent capacitance associated to each dipolar element of a flat metasurface, and we show that this is also able to accurately model the phenomenology involved in strong coupling between the metasurf...
Energy Technology Data Exchange (ETDEWEB)
Wanne, Toivo; Johansson, Erik; Potyondy, David [Saanio and Riekkola Oy, Helsinki (Finland)
2004-02-01
SKB is planning to perform a large-scale pillar stability experiment called APSE (Aespoe Pillar Stability Experiment) at Aespoe HRL. The study is focused on understanding and control of progressive rock failure in hard crystalline rock and damage caused by high stresses. The elastic thermo-mechanical modeling was carried out in three dimensions because of the complex test geometry and in-situ stress tensor by using a finite-difference modeling software FLAC3D. Cracking and damage formation were modeled in the area of interest (pillar between two large scale holes) in two dimensions by using the Particle Flow Code (PFC), which is based on particle mechanics. FLAC and PFC were coupled to minimize the computer resources and the computing time. According to the modeling the initial temperature rises from 15 deg C to about 65 deg C in the pillar area during the heating period of 120 days. The rising temperature due to thermal expansion induces stresses in the pillar area and after 120 days heating the stresses have increased about 33% from the excavation induced maximum stress of 150 MPa to 200 MPa in the end of the heating period. The results from FLAC3D model showed that only regions where the crack initiation stress has exceeded were identified and they extended to about two meters down the hole wall. These could be considered the areas where damage may occur during the in-situ test. When the other hole is pressurized with a 0.8 MPa confining pressure it yields that 5 MPa more stress is needed to damage the rock than without confining pressure. This makes the damaged area in some degree smaller. High compressive stresses in addition to some tensile stresses might induce some AE (acoustic emission) activity in the upper part of the hole from the very beginning of the test and are thus potential areas where AE activities may be detected. Monitoring like acoustic emissions will be measured during the test execution. The 2D coupled PFC-FLAC modeling indicated that
Advances in the land surface model (LSM) and planetary boundary layer (PBL) components of the WRF-CMAQ coupled meteorology and air quality modeling system are described. The aim of these modifications was primarily to improve the modeling of ground level concentrations of trace c...
Helsen, M.M.|info:eu-repo/dai/nl/325802459; van de Wal, R.S.W.|info:eu-repo/dai/nl/101899556; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van de Berg, W.J.|info:eu-repo/dai/nl/304831611; Oerlemans, J.|info:eu-repo/dai/nl/06833656X
2012-01-01
It is notoriously difficult to couple surface mass balance (SMB) results from climate models to the changing geometry of an ice sheet model. This problem is traditionally avoided by using only accumulation from a climate model, and parameterizing the meltwater run-off as a function of temperature,
Helsen, M.M.; van de Wal, R.S.W.; van den Broeke, M.R.; van de Berg, W.J.; Oerlemans, J.
2011-01-01
It is notoriously difficult to couple surface mass balance (SMB) results from climate models to the changing geometry of an ice sheet model. This problem is traditionally avoided by using only accumulation fields from a climate model, and deriving SMB by parameterizing 5 the run-off as a function of
A system of conservative regridding for ice–atmosphere coupling in a General Circulation Model (GCM
Directory of Open Access Journals (Sweden)
R. Fischer
2014-05-01
Full Text Available The method of elevation classes, in which the ice surface model is run at multiple elevations within each grid cell, has proven to be a useful way for a low-resolution atmosphere inside a general circulation model (GCM to produce high-resolution downscaled surface mass balance fields for use in one-way studies coupling atmospheres and ice flow models. Past uses of elevation classes have failed to conserve mass and energy because the transformation used to regrid to the atmosphere was inconsistent with the transformation used to downscale to the ice model. This would cause problems for two-way coupling. A strategy that resolves this conservation issue has been designed and is presented here. The approach identifies three grids between which data must be regridded and five transformations between those grids required by a typical coupled atmosphere–ice flow model. This paper develops a theoretical framework for the problem and shows how each of these transformations may be achieved in a consistent, conservative manner. These transformations are implemented in Glint2, a library used to couple atmosphere models with ice models. Source code and documentation are available for download. Confounding real-world issues are discussed, including the use of projections for ice modeling, how to handle dynamically changing ice geometry, and modifications required for finite element ice models.
Measurement and modeling of transfer functions for lightning coupling into the Sago mine.
Energy Technology Data Exchange (ETDEWEB)
Morris, Marvin E.; Higgins, Matthew B.
2007-04-01
This report documents measurements and analytical modeling of electromagnetic transfer functions to quantify the ability of cloud-to-ground lightning strokes (including horizontal arc-channel components) to couple electromagnetic energy into the Sago mine located near Buckhannon, WV. Two coupling mechanisms were measured: direct and indirect drive. These transfer functions are then used to predict electric fields within the mine and induced voltages on conductors that were left abandoned in the sealed area of the Sago mine.
Mahaffey, Barbara A.
2010-01-01
A psychoeducational model for improving couple communication is proposed. An important goal in couples counseling is to assist couples in resolving communication conflicts. The proposed communication model helps to establish a therapeutic environment that encourages insight, therapeutic alliance formation, catharsis, self-disclosure, symptom…
Distributed models coupling soakaways, urban drainage and groundwater
DEFF Research Database (Denmark)
Roldin, Maria Kerstin
Alternative methods for stormwater management in urban areas, also called Water Sensitive Urban Design (WSUD) methods, have become increasingly important for the mitigation of urban stormwater management problems such as high runoff volumes, combined sewage overflows, poor water quality....... In order to assess these effects at local- and catchment-scale, there is a need for reliable and efficient modeling tools that can account for the interaction between the various urban water systems involved. This thesis focuses on small-scale stormwater infiltration structures, often called soakaways...... to manage the bi-directional interaction between stormwater infiltration and groundwater 3. Develops suitable upscaling/downscaling techniques for the integrated soakaway model 4. Assesses the effects of extensive use of soakaways on sewer and groundwater flows in case studies Based on a review...
Coupling of Groundwater Transport and Plant Uptake Models
DEFF Research Database (Denmark)
Rein, Arno; Bauer-Gottwein, Peter; Trapp, Stefan
2010-01-01
Plants significantly influence contaminant transport and fate. Important processes are uptake of soil and groundwater contaminants, as well as biodegradation in plants and their root zones. Models for the prediction of chemical uptake into plants are required for the setup of mass balances in env...... to groundwater transport simulation tools. Exemplary simulations of plant uptake were carried out, in order to estimate concentrations in the soilplant- air system and the influence of plants on contaminant mass fluxes from soil to groundwater.......Plants significantly influence contaminant transport and fate. Important processes are uptake of soil and groundwater contaminants, as well as biodegradation in plants and their root zones. Models for the prediction of chemical uptake into plants are required for the setup of mass balances...
A Coupled Chemical and Mass Transport Model for Concrete Durability
DEFF Research Database (Denmark)
Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica
2012-01-01
In this paper a general continuum theory is used to evaluate the service life of cement based materials, in terms of mass transport processes and chemical degradation of the solid matrix. The model established is a reactive mass transport model, based on an extended version of the Poisson...... their individual sorption hysteresis isotherm which is of great importance when describing non fully water saturated system e.g. caused by time depended boundary conditions. Chemical equilibrium is also established in each node of the discrete system, where the rate of chemical degradation is determined...... by the rate of mass transport only. A consequence of the source or sink term, is the assumption that equilibrium is reached instantaneously in each time step considered. Some numerical problems was found, where the residual requirements for the chemical equilibrium was not reached. Small imbalances, in e...
Ageing of polymer bonds: a coupled chemomechanical modelling approach
Dippel, Benedikt; Johlitz, Michael; Lion, Alexander
2014-05-01
With the increasing number of requirements on joinings, it gets more and more important to understand and predict an assemblies properties. Nowadays, in industrial applications, combinations of different materials get more common. In most of those cases, it is, besides other advantages, useful to connect such parts with adhesives to avoid local cells. Thus, the knowledge about the mechanical behaviour of adhesives over the whole time of utilisation is an essential element of engineering. As it is well known, ageing due to environmental influences such as oxygen, radiation, ozone and others plays a major role in polymers properties. So, for the prediction of applicability over the whole lifetime of a technical component, the change in mechanical properties due to ageing is necessary. In this contribution, we introduce a material model which takes into account the internal structure of an adhesive. Therefore, an interphase zone is introduced. In the interphase, which is developed due to the contact of an adhesive with an adherent, the materials properties change continuously from the surface to the centre of the joint, where the polymer is in a bulky state. Built up on this geometry dependency, the materials ageing as a function of the position is described. To model the change of the polymers state, we use a parameter representing chain scission processes and another one for the reformation of a new network. In a last step, the model is transferred into a finite element code for exemplary calculations.
Cellular automata model of magnetospheric-ionospheric coupling
Directory of Open Access Journals (Sweden)
B. V. Kozelov
2003-09-01
Full Text Available We propose a cellular automata model (CAM to describe the substorm activity of the magnetospheric-ionospheric system. The state of each cell in the model is described by two numbers that correspond to the energy content in a region of the current sheet in the magnetospheric tail and to the conductivity of the ionospheric domain that is magnetically connected with this region. The driving force of the system is supposed to be provided by the solar wind that is convected along the two boundaries of the system. The energy flux inside is ensured by the penetration of the energy from the solar wind into the array of cells (magnetospheric tail with a finite velocity. The third boundary (near to the Earth is closed and the fourth boundary is opened, thereby modeling the flux far away from the tail. The energy dissipation in the system is quite similar to other CAM models, when the energy in a particular cell exceeds some pre-defined threshold, and the part of the energy excess is redistributed between the neighbouring cells. The second number attributed to each cell mimics ionospheric conductivity that can allow for a part of the energy to be shed on field-aligned currents. The feedback between "ionosphere" and "magnetospheric tail" is provided by the change in a part of the energy, which is redistributed in the tail when the threshold is surpassed. The control parameter of the model is the z-component of the interplanetary magnetic field (Bz IMF, "frozen" into the solar wind. To study the internal dynamics of the system at the beginning, this control parameter is taken to be constant. The dynamics of the system undergoes several bifurcations, when the constant varies from - 0.6 to - 6.0. The Bz IMF input results in the periodic transients (activation regions and the inter-transient period decreases with the decrease of Bz. At the same time the onset of activations in the array shifts towards the "Earth". When the modulus of the Bz IMF exceeds some
Cellular automata model of magnetospheric-ionospheric coupling
Directory of Open Access Journals (Sweden)
B. V. Kozelov
Full Text Available We propose a cellular automata model (CAM to describe the substorm activity of the magnetospheric-ionospheric system. The state of each cell in the model is described by two numbers that correspond to the energy content in a region of the current sheet in the magnetospheric tail and to the conductivity of the ionospheric domain that is magnetically connected with this region. The driving force of the system is supposed to be provided by the solar wind that is convected along the two boundaries of the system. The energy flux inside is ensured by the penetration of the energy from the solar wind into the array of cells (magnetospheric tail with a finite velocity. The third boundary (near to the Earth is closed and the fourth boundary is opened, thereby modeling the flux far away from the tail. The energy dissipation in the system is quite similar to other CAM models, when the energy in a particular cell exceeds some pre-defined threshold, and the part of the energy excess is redistributed between the neighbouring cells. The second number attributed to each cell mimics ionospheric conductivity that can allow for a part of the energy to be shed on field-aligned currents. The feedback between "ionosphere" and "magnetospheric tail" is provided by the change in a part of the energy, which is redistributed in the tail when the threshold is surpassed. The control parameter of the model is the z-component of the interplanetary magnetic field (Bz IMF, "frozen" into the solar wind. To study the internal dynamics of the system at the beginning, this control parameter is taken to be constant. The dynamics of the system undergoes several bifurcations, when the constant varies from - 0.6 to - 6.0. The Bz IMF input results in the periodic transients (activation regions and the inter-transient period decreases with the decrease of Bz. At the same time the onset of activations in the array shifts towards the "Earth". When the modulus of the Bz IMF exceeds some
Report on Modeling Coupled Processes in the Near Field of a Clay Repository
Energy Technology Data Exchange (ETDEWEB)
Liu, Hui -Hai [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, Jim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Li, Lianchong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Asahina, Daisuke [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Fei [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2012-08-01
Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world. Coupled thermal, hydrological, mechanical, and chemical (THMC) processes have a significant impact on the long-term safety of a clay repository. For example, the excavation damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability. This report documents results from three R&D activities: (1) implementation and validation of constitutive relationships, (2) development of a discrete fracture network (DFN) model for investigating coupled processes in the EDZ, and (3) development of a THM model for the FE tests at Mont Terri, Switzerland, for the purpose of model validation. The overall objective of these activities is to provide an improved understanding of EDZ evolution in clay repositories and the associated coupled processes, and to develop advanced relevant modeling capabilities.
A regime-switching copula approach to modeling day-ahead prices in coupled electricity markets
DEFF Research Database (Denmark)
Pircalabu, Anca; Benth, Fred Espen
2017-01-01
to model pairs of day-ahead electricity prices in coupled European markets. While capturing key stylized facts empirically substantiated in the literature, this model easily allows us to 1) deviate from the assumption of normal margins and 2) include a more detailed description of the dependence between......The recent price coupling of many European electricity markets has triggered a fundamental change in the interaction of day-ahead prices, challenging additionally the modeling of the joint behavior of prices in interconnected markets. In this paper we propose a regime-switching AR–GARCH copula...
Chaos analysis and delayed-feedback control in a discrete dynamic coupled map traffic model
Fang, Yaling; Shi, Zhongke
2015-03-01
The presence of chaos in traffic flow is studied using a modified discrete dynamic coupled map model which is derived from both the flow-density-speed fundamental diagram and Del Castillo's speed-density model. The modified model employs occupancy as its new variable and introduces a coupling strength with the consideration of effect of the front adjacent vehicle. And we analyze its stability of the control system and provide a procedure to design the decentralized delayed-feedback controllers for the traffic control system. These theoretical results are illustrated by numerical simulations.
Charge and spin current statistics of the open Hubbard model with weak coupling to the environment.
Buča, Berislav; Prosen, Tomaž
2017-05-01
Based on generalization and extension of our previous work [Phys. Rev. Lett. 112, 067201 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.067201] to multiple independent Markovian baths we will compute the charge and spin current statistics of the open Hubbard model with weak system-bath coupling up to next-to-leading order in the coupling parameter. Only the next-to-leading and higher orders depend on the Hubbard interaction parameter. The physical results are related to those for the XXZ model in the analogous setup implying a certain universality, which potentially holds in this class of nonequilibrium models.
Modeling of hybridized infrared arrays for characterization of interpixel capacitive coupling
Donlon, Kevan; Ninkov, Zoran; Baum, Stefi; Cheng, Linpeng
2017-02-01
Interpixel capacitance (IPC) is a deterministic electronic coupling resulting in a portion of signal incident on one pixel of a hybridized detector array being measured in adjacent pixels. Data collected by light sensitive HgCdTe arrays that exhibit this coupling typically goes uncorrected or is corrected by treating the coupling as a fixed point spread function. Evidence suggests that this coupling is not uniform across signal and background levels. Subarrays of pixels using design parameters based upon HgCdTe indium hybridized arrays akin to those contained in the James Webb Space Telescope's NIRcam have been modeled from first principles using Lumerical DEVICE Software. This software simultaneously solves Poisson's equation and the drift diffusion equations yielding charge distributions and electric fields. Modeling of this sort generates the local point spread function across a range of detector parameters. This results in predictive characterization of IPC across scene and device parameters that would permit proper photometric correction and signal restoration to the data. Additionally, the ability to visualize potential distributions and couplings as generated by the models yields insight that can be used to minimize IPC coupling in the design of future detectors.
Zambon, Joseph B.; He, Ruoying; Warner, John C.
2014-01-01
The coupled ocean–atmosphere–wave–sediment transport (COAWST) model is used to hindcast Hurricane Ivan (2004), an extremely intense tropical cyclone (TC) translating through the Gulf of Mexico. Sensitivity experiments with increasing complexity in ocean–atmosphere–wave coupled exchange processes are performed to assess the impacts of coupling on the predictions of the atmosphere, ocean, and wave environments during the occurrence of a TC. Modest improvement in track but significant improvement in intensity are found when using the fully atmosphere–ocean-wave coupled configuration versus uncoupled (e.g., standalone atmosphere, ocean, or wave) model simulations. Surface wave fields generated in the fully coupled configuration also demonstrates good agreement with in situ buoy measurements. Coupled and uncoupled model-simulated sea surface temperature (SST) fields are compared with both in situ and remote observations. Detailed heat budget analysis reveals that the mixed layer temperature cooling in the deep ocean (on the shelf) is caused primarily by advection (equally by advection and diffusion).
Fermionic extensions of the Standard Model in light of the Higgs couplings
Energy Technology Data Exchange (ETDEWEB)
Bizot, Nicolas; Frigerio, Michele [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, Place Eugéne Bataillon, F-34095 Montpellier (France)
2016-01-08
As the Higgs boson properties settle, the constraints on the Standard Model extensions tighten. We consider all possible new fermions that can couple to the Higgs, inspecting sets of up to four chiral multiplets. We confront them with direct collider searches, electroweak precision tests, and current knowledge of the Higgs couplings. The focus is on scenarios that may depart from the decoupling limit of very large masses and vanishing mixing, as they offer the best prospects for detection. We identify exotic chiral families that may receive a mass from the Higgs only, still in agreement with the hγγ signal strength. A mixing θ between the Standard Model and non-chiral fermions induces order θ{sup 2} deviations in the Higgs couplings. The mixing can be as large as θ∼0.5 in case of custodial protection of the Z couplings or accidental cancellation in the oblique parameters. We also notice some intriguing effects for much smaller values of θ, especially in the lepton sector. Our survey includes a number of unconventional pairs of vector-like and Majorana fermions coupled through the Higgs, that may induce order one corrections to the Higgs radiative couplings. We single out the regions of parameters where hγγ and hgg are unaffected, while the hγZ signal strength is significantly modified, turning a few times larger than in the Standard Model in two cases. The second run of the LHC will effectively test most of these scenarios.
2-way coupling the hydrological land surface model PROMET with the regional climate model MM5
Directory of Open Access Journals (Sweden)
F. Zabel
2013-05-01
Full Text Available Most land surface hydrological models (LSHMs consider land surface processes (e.g. soil–plant–atmosphere interactions, lateral water flows, snow and ice in a spatially detailed manner. The atmosphere is considered as exogenous driver, neglecting feedbacks between the land surface and the atmosphere. On the other hand, regional climate models (RCMs generally simulate land surface processes through coarse descriptions and spatial scales but include land–atmosphere interactions. What is the impact of the differently applied model physics and spatial resolution of LSHMs on the performance of RCMs? What feedback effects are induced by different land surface models? This study analyses the impact of replacing the land surface module (LSM within an RCM with a high resolution LSHM. A 2-way coupling approach was applied using the LSHM PROMET (1 × 1 km2 and the atmospheric part of the RCM MM5 (45 × 45 km2. The scaling interface SCALMET is used for down- and upscaling the linear and non-linear fluxes between the model scales. The change in the atmospheric response by MM5 using the LSHM is analysed, and its quality is compared to observations of temperature and precipitation for a 4 yr period from 1996 to 1999 for the Upper Danube catchment. By substituting the Noah-LSM with PROMET, simulated non-bias-corrected near-surface air temperature improves for annual, monthly and daily courses when compared to measurements from 277 meteorological weather stations within the Upper Danube catchment. The mean annual bias was improved from −0.85 to −0.13 K. In particular, the improved afternoon heating from May to September is caused by increased sensible heat flux and decreased latent heat flux as well as more incoming solar radiation in the fully coupled PROMET/MM5 in comparison to the NOAH/MM5 simulation. Triggered by the LSM replacement, precipitation overall is reduced; however simulated precipitation amounts are still of high uncertainty, both
A Newton-Krylov solver with a loosely-coupled turbulence model for aerodynamic flows
Blanco, Max
Computational solutions of the Navier-Stokes equations have proven to be a useful tool in the design of aircraft. A Newton-Krylov flow solver for unstructured grids is developed in order to demonstrate that a formulation in which the mean-flow and turbulence mechanism equations are loosely coupled can be more economical than a similar fully-coupled formulation. The Favre-averaged Navier-Stokes equations are derived for steady two-dimensional flows, and the turbulence mechanism is described. These equations constitute a model of the physics of aerodynamic flows. The model is validated against experimental data. The objective of this thesis is to examine a means to improve the iterative process by which the solutions are generated. The Newton-Krylov iteration is selected in order to refine the solution, and its features examined. The authors of current Newton-Krylov techniques have fully coupled the turbulence mechanism to the Navier-Stokes equations. A contrast and comparison study made here between the fully-coupled formulation and a loosely-coupled alternative favours the latter. An 'equivalent function evaluation' metric is selected for comparison purposes, and is assessed by means of diverse computers. Published results which use the metric are located, and the present loosely-coupled formulation for unstructured grids is found to be significantly faster in this metric than similar fully-coupled formulations. The advantages of the loosely-coupled formulation with respect to the fully-coupled formulation are stated and future avenues for exploitation of the proposed technology are examined. Appendices consist of: a formalism for the Favre average and consequences of its derivation; a short tract on Taylor series; and an essay on the Frechet differential.
Computer model of a reverberant and parallel circuit coupling
Kalil, Camila de Andrade; de Castro, Maria Clícia Stelling; Cortez, Célia Martins
2017-11-01
The objective of the present study was to deepen the knowledge about the functioning of the neural circuits by implementing a signal transmission model using the Graph Theory in a small network of neurons composed of an interconnected reverberant and parallel circuit, in order to investigate the processing of the signals in each of them and the effects on the output of the network. For this, a program was developed in C language and simulations were done using neurophysiological data obtained in the literature.
Directory of Open Access Journals (Sweden)
Jessica Melbourne-Thomas
2011-09-01
Full Text Available Transdisciplinary approaches that consider both socioeconomic and biophysical processes are central to understanding and managing rapid change in coral reef systems worldwide. To date, there have been limited attempts to couple the two sets of processes in dynamic models for coral reefs, and these attempts are confined to reef systems in developed countries. We present an approach to coupling existing biophysical and socioeconomic models for coral reef systems in the Mexican state of Quintana Roo. The biophysical model is multiscale, using dynamic equations to capture local-scale ecological processes on individual reefs, with reefs connected at regional scales by the ocean transport of larval propagules. The agent-based socioeconomic model simulates changes in tourism, fisheries, and urbanization in the Quintana Roo region. Despite differences in the formulation and currencies of the two models, we were able to successfully modify and integrate them to synchronize and define information flows and feedbacks between them. A preliminary evaluation of the coupled model system indicates that the model gives reasonable predictions for fisheries and ecological variables and can be used to examine scenarios for future social-ecological change in Quintana Roo. We provide recommendations for where efforts might usefully be focused in future attempts to integrate models of biophysical and socioeconomic processes, based on the limitations of our coupled system.
A numerical model of hydro-thermo-mechanical coupling in a fractured rock mass
Energy Technology Data Exchange (ETDEWEB)
Bower, Kathleen Marie [Univ. of New Mexico, Albuquerque, NM (United States)
1996-06-01
Coupled hydro-thermo-mechanical codes with the ability to model fractured materials are used for predicting groundwater flow behavior in fractured aquifers containing thermal sources. The potential applications of such a code include the analysis of groundwater behavior within a geothermal reservoir. The capability of modeling hydro-thermo systems with a dual porosity, fracture flow model has been previously developed in the finite element code, FEHM. FEHM has been modified to include stress coupling with the dual porosity feature. FEHM has been further developed to implicitly couple the dependence of fracture hydraulic conductivity on effective stress within two dimensional, saturated aquifers containing fracture systems. The cubic law for flow between parallel plates was used to model fracture permeability. The Bartin-Bandis relationship was used to determine the fracture aperture within the cubic law. The code used a Newton Raphson iteration to implicitly solve for six unknowns at each node. Results from a model of heat flow from a reservoir to the moving fluid in a single fracture compared well with analytic results. Results of a model showing the increase in fracture flow due to a single fracture opening under fluid pressure compared well with analytic results. A hot dry rock, geothermal reservoir was modeled with realistic time steps indicating that the modified FEHM code does successfully model coupled flow problems with no convergence problems.
Deterministic-statistical model coupling in a DSS for river-basin management
de Kok, Jean-Luc; Booij, Martijn J.
2009-01-01
This paper presents a method for appropriate coupling of deterministic and statistical models. In the decision-support system for the Elbe river, a conceptual rainfall-runoff model is used to obtain the discharge statistics and corresponding average number of flood days, which is a key input
A Dyadic Approach: Applying a Developmental-Conceptual Model to Couples Coping with Chronic Illness
Checton, Maria G.; Magsamen-Conrad, Kate; Venetis, Maria K.; Greene, Kathryn
2015-01-01
The purpose of the present study was to apply Berg and Upchurch's developmental-conceptual model toward a better understanding of how couples cope with chronic illness. Specifically, a model was hypothesized in which proximal factors (relational quality), dyadic appraisal (illness interference), and dyadic coping (partner support) influence…
Directory of Open Access Journals (Sweden)
Long Zhang
2013-01-01
Full Text Available The power source with the limited life span has motivated the development of the energy harvesters that can scavenge the ambient environment energy and convert it into the electrical energy. With the coupled field characteristics of structure to electricity, piezoelectric energy harvesters are under consideration as a means of converting the mechanical energy to the electrical energy, with the goal of realizing completely self-powered sensor systems. In this paper, two previous models in the literatures for predicting the open-circuit and close-circuit voltages of a piezoelectric cantilever bimorph (PCB energy harvester are first described, that is, the mechanical equivalent spring mass-damper model and the electrical equivalent circuit model. Then, the development of an enhanced coupled field model for the PCB energy harvester based on another previous model in the literature using a conservation of energy method is presented. Further, the laboratory experiments are carried out to evaluate the enhanced coupled field model and the other two previous models in the literatures. The comparison results show that the enhanced coupled field model can better predict the open-circuit and close-circuit voltages of the PCB energy harvester with a proof mass bonded at the free end of the structure in order to increase the energy-harvesting level of the system.
Matrix Solution of Coupled Differential Equations and Looped Car Following Models
McCartney, Mark
2008-01-01
A simple mathematical model for the behaviour of how vehicles follow each other along a looped stretch of road is described. The resulting coupled first order differential equations are solved using appropriate matrix techniques and the physical significance of the model is discussed. A number possible classroom exercises are suggested to help…
Höhn, P.A.|info:eu-repo/dai/nl/330827952; Kubalová, E.; Tsobanjan, A.
2011-01-01
We apply the effective approach to evaluating semiclassical relational dynamics to the closed Friedman–Robertson–Walker cosmological model filled with a minimally coupled massive scalar field. This model is interesting for studying relational dynamics in a more general setting because (i) it
CSIR Research Space (South Africa)
Beraki, AF
2015-11-01
Full Text Available The study compares one- and two-tiered forecasting systems as represented by the South African Weather Service Coupled Model and its atmosphere-only version. In this comparative framework, the main difference between these global climate models...
A multiscale model on hospital infections coupling macro and micro dynamics
Wang, Xia; Tang, Sanyi
2017-09-01
A multiscale model of hospital infections coupling the micro model of the growth of bacteria and the macro model describing the transmission of the bacteria among patients and health care workers (HCWs) was established to investigate the effects of antibiotic treatment on the transmission of the bacteria among patients and HCWs. The model was formulated by viewing the transmission rate from infected patients to HCWs and the shedding rate of bacteria from infected patients to the environment as saturated functions of the within-host bacterial load. The equilibria and the basic reproduction number of the coupled system were studied, and the global dynamics of the disease free equilibrium and the endemic equilibrium were analyzed in detail by constructing two Lyapunov functions. Furthermore, effects of drug treatment in the within-host model on the basic reproduction number and the dynamics of the coupled model were studied by coupling a pharmacokinetics model with the within-host model. Sensitive analysis indicated that the growth rate of the bacteria, the maximum drug effect and the dosing interval are the three most sensitive parameters contributing to the basic reproduction number. Thus, adopting ;wonder; drugs to decrease the growth rate of the bacteria or to increase the drug's effect is the most effective measure but changing the dosage regime is also effective. A quantitative criterion of how to choose the best dosage regimen can also be obtained from numerical results.
Ned Nikolova; Karl F. Zeller
2003-01-01
A new biophysical model (FORFLUX) is presented to study the simultaneous exchange of ozone, carbon dioxide, and water vapor between terrestrial ecosystems and the atmosphere. The model mechanistically couples all major processes controlling ecosystem flows trace gases and water implementing recent concepts in plant eco-physiology, micrometeorology, and soil hydrology....
Filter designs based on coupled transmission line model for double split ring resonators
DEFF Research Database (Denmark)
Yan, Lei; Tang, Meng; Krozer, Viktor
2012-01-01
This work presents a systematic way to design filters based on coupled transmission line model of the microstrip rectangular double split ring resonators (DSRRs). This model allows to estimate all resonance modes of DSRR and extract the quality factors of the structure for filter synthesis purpose...
GEOCLIM reloaded (v 1.0): a new coupled earth system model for past climate change
Arndt, S.; Regnier, P.; Goddéris, Y.; Donnadieu, Y.
2011-01-01
We present a new version of the coupled Earth system model GEOCLIM. The new release, GEOCLIM reloaded (v 1.0), links the existing atmosphere and weathering modules to a novel, temporally and spatially resolved model of the global ocean circulation, which provides a physical framework for a
Model of natural ventilation by using a coupled thermal-airflow simulation program
DEFF Research Database (Denmark)
Oropeza-Perez, Ivan; Østergaard, Poul Alberg; Remmen, Arne
2012-01-01
This article presents a model of natural ventilation of buildings at the stage of design and a consequence of the behaviour of the occupants. An evaluation is made by coupling multizone air modelling and thermal building simulation using a deterministic set of input factors comprising among others...
Higher dimensional models of cross-coupled oscillators and application to design
Elwakil, Ahmed S.
2010-06-01
We present four-dimensional and five-dimensional models for classical cross-coupled LC oscillators. Using these models, sinusoidal oscillation condition, frequency and amplitude can be found. Further, undesired behaviors such as relaxation-mode oscillations and latchup can be explained and detected. A simple graphical design procedure is also described. © 2010 World Scientific Publishing Company.
DEFF Research Database (Denmark)
Jabbari, Masoud; Hosseinzadeh, Azin
2013-01-01
In the present study the numerical model in 2D is used to study the solidification bahavior of the gray cast iron. The conventional heat transfer is coupled with the proposed micro-model to predict the amount of different phases, i.e. total austenite (c) phase, graphite (G) and cementite (C...
A Transplanet model of magnetosphere-ionosphere coupling at Earth, Mars, Jupiter, (Saturn and Venus)
Indurain, M.; Goutenoir, A.; Bouchemit, M.; Blelly, P.-L.; Marchaudon, A.; Gangloff, M.; Jourdane, N.; André, N.; Génot, V.
2017-09-01
This PSWS service includes a Transplanet model of magnetosphere-ionosphere coupling at Earth, Mars, and Jupiter that enable the users to made runs on request of the model, archive and/or connect the results of their simulation runs to various tools developed in the Virtual Observatory.
Vibronic resonances sustain excited state coherence in light harvesting proteins at room temperature
Novelli, Fabio; Roozbeh, Ashkan; Wilk, Krystyna E; Curmi, Paul M G; Davis, Jeffrey A
2015-01-01
Until recently it was believed that photosynthesis, a fundamental process for life on earth, could be fully understood with semi-classical models. However, puzzling quantum phenomena have been observed in several photosynthetic pigment-protein complexes, prompting questions regarding the nature and role of these effects. Recent attention has focused on discrete vibrational modes that are resonant or quasi-resonant with excitonic energy splittings and strongly coupled to these excitonic states. Here we report a series of experiments that unambiguously identify excited state coherent superpositions that dephase on the timescale of the excited state lifetime. Low energy (56 cm-1) oscillations on the signal intensity provide direct experimental evidence for the role of vibrational modes resonant with excitonic splittings in sustaining coherences involving different excited excitonic states at physiological temperature.
Sediment dynamics in the Adriatic Sea investigated with coupled models
Sherwood, Christopher R.; Book, Jeffrey W.; Carniel, Sandro; Cavaleri, Luigi; Chiggiato, Jacopo; Das, Himangshu; Doyle, James D.; Harris, Courtney K.; Niedoroda, Alan W.; Perkins, Henry; Poulain, Pierre-Marie; Pullen, Julie; Reed, Christopher W.; Russo, Aniello; Sclavo, Mauro; Signell, Richard P.; Traykovski, Peter A.; Warner, John C.
2004-01-01
Several large research programs focused on the Adriatic Sea in winter 2002-2003, making it an exciting place for sediment dynamics modelers (Figure 1). Investigations of atmospheric forcing and oceanic response (including wave generation and propagation, water-mass formation, stratification, and circulation), suspended material, bottom boundary layer dynamics, bottom sediment, and small-scale stratigraphy were performed by European and North American researchers participating in several projects. The goal of EuroSTRATAFORM researchers is to improve our ability to understand and simulate the physical processes that deliver sediment to the marine environment and generate stratigraphic signatures. Scientists involved in the Po and Apennine Sediment Transport and Accumulation (PASTA) experiment benefited from other major research programs including ACE (Adriatic Circulation Experiment), DOLCE VITA (Dynamics of Localized Currents and Eddy Variability in the Adriatic), EACE (the Croatian East Adriatic Circulation Experiment project), WISE (West Istria Experiment), and ADRICOSM (Italian nowcasting and forecasting) studies.
Dai, Qingli; Sadd, Martin H.; You, Zhanping
2006-09-01
This study presents a finite element (FE) micromechanical modelling approach for the simulation of linear and damage-coupled viscoelastic behaviour of asphalt mixture. Asphalt mixture is a composite material of graded aggregates bound with mastic (asphalt and fine aggregates). The microstructural model of asphalt mixture incorporates an equivalent lattice network structure whereby intergranular load transfer is simulated through an effective asphalt mastic zone. The finite element model integrates the ABAQUS user material subroutine with continuum elements for the effective asphalt mastic and rigid body elements for each aggregate. A unified approach is proposed using Schapery non-linear viscoelastic model for the rate-independent and rate-dependent damage behaviour. A finite element incremental algorithm with a recursive relationship for three-dimensional (3D) linear and damage-coupled viscoelastic behaviour is developed. This algorithm is used in a 3D user-defined material model for the asphalt mastic to predict global linear and damage-coupled viscoelastic behaviour of asphalt mixture.For linear viscoelastic study, the creep stiffnesses of mastic and asphalt mixture at different temperatures are measured in laboratory. A regression-fitting method is employed to calibrate generalized Maxwell models with Prony series and generate master stiffness curves for mastic and asphalt mixture. A computational model is developed with image analysis of sectioned surface of a test specimen. The viscoelastic prediction of mixture creep stiffness with the calibrated mastic material parameters is compared with mixture master stiffness curve over a reduced time period.In regard to damage-coupled viscoelastic behaviour, cyclic loading responses of linear and rate-independent damage-coupled viscoelastic materials are compared. Effects of particular microstructure parameters on the rate-independent damage-coupled viscoelastic behaviour are also investigated with finite element
PCB modeling in the Gulf of Lions using a 3D coupled model
Alekseenko, Elena; Thouvenin, Bénédicte; Tixier, Céline; Tronczynski, Jacek; Garreau, Pierre; Verney, Romaric; Carlotti, Francois; Espinasse, Boris; Queguiner, Bernard; Baklouti, Melika
2013-04-01
Polychlorobiphenyls (PCBs) are synthetic chlorinated organic compounds, which were widely used in many industrial materials. These compounds are persistent, bioaccumulable and toxic for living organisms. The riverine and atmospheric fluxes are the major routes of entry for these chemicals into marine ecosystems, where they are now embedded in natural biogeochemical cycles (Lohmann et al. 2007). Because of bioaccumulation and biomagnification processes in food webs, even nowadays, these compounds may attain dangerous concentration levels especially in the top predators including marine mammals. The contamination of marine biota by PCBs in Mediterranean has also become a matter of concern as the concentrations in some species are at levels putting them at risk for significant biological effects. This may pose potential human health risks in commercial edible species (Carpenter 2006). Planktonic populations play a key role in the trophic food webs in marine ecosystems by the mobilisation and transfer of energy and organic matter towards higher trophic levels. This work aims at a better understanding of the role of plankton in the transfer of PCBs to higher trophic levels in the Gulf of Lions (Mediterranean) by coupling of biogeochemical, ecological and hydrodynamical processes. Modeling is a powerful tool for coupling processes of different disciplines and scales. The recent development of 3D hydrodynamic, hydrosedimentary and biogeochemical models in the Mediterranean (André et al, 2005,2009, Ulses et al, 2008, Dufois et al, 2008, Auger et al, 2011), enables feasibility testing of coupling these models with transfer processes of chemical contaminants. The lack of detailed observations in the sea and the significant uncertainty on contaminants inputs prevent from a proper validation of such modeling tests. However, these tools are very useful to assess the influence of fast processes on the transfer of contaminants to bioaccumulative species. Sensitivity analysis
Motesharrei, Safa; Rivas, Jorge; Kalnay, Eugenia; Asrar, Ghassem R.; Busalacchi, Antonio J.; Cahalan, Robert F.; Cane, Mark A.; Colwell, Rita R.; Feng, Kuishuang; Franklin, Rachel S.;
2016-01-01
Over the last two centuries, the impact of the Human System has grown dramatically, becoming strongly dominant within the Earth System in many different ways. Consumption, inequality, and population have increased extremely fast, especially since about 1950, threatening to overwhelm the many critical functions and ecosystems of the Earth System. Changes in the Earth System, in turn, have important feedback effects on the Human System, with costly and potentially serious consequences. However, current models do not incorporate these critical feedbacks. We argue that in order to understand the dynamics of either system, Earth System Models must be coupled with Human System Models through bidirectional couplings representing the positive, negative, and delayed feedbacks that exist in the real systems. In particular, key Human System variables, such as demographics, inequality, economic growth, and migration, are not coupled with the Earth System but are instead driven by exogenous estimates, such as UN population projections. This makes current models likely to miss important feedbacks in the real Earth-Human system, especially those that may result in unexpected or counterintuitive outcomes, and thus requiring different policy interventions from current models. The importance and imminence of sustainability challenges, the dominant role of the Human System in the Earth System, and the essential roles the Earth System plays for the Human System, all call for collaboration of natural scientists, social scientists, and engineers in multidisciplinary research and modeling to develop coupled Earth-Human system models for devising effective science-based policies and measures to benefit current and future generations.
Modeling Sustainability: Population, Inequality, Consumption, and Bidirectional Coupling of the Earth and Human Systems
Energy Technology Data Exchange (ETDEWEB)
Motesharrei, Safa; Rivas, Jorge; Kalnay, Eugenia; Asrar, Ghassem R.; Busalacchi, Antonio J.; Cahalan, Robert F.; Cane, Mark A.; Colwell, Rita R.; Feng, Kuishuang; Franklin, Rachel S.; Hubacek, Klaus; Miralles-Wilhelm, Fernando; Miyoshi, Takemasa; Ruth, Matthias; Sagdeev, Roald; Shirmohammadi, Adel; Shukla, Jagadish; Srebric, Jelena; Yakovenko, Victor M.; Zeng, Ning
2016-12-11
Over the last two centuries, the impact of the Human System has grown dramatically, becoming strongly dominant within the Earth System in many different ways. Consumption, inequality, and population have increased extremely fast, especially since about 1950, threatening to overwhelm the many critical functions and ecosystems of the Earth System. Changes in the Earth System, in turn, have important feedback effects on the Human System, with costly and potentially serious consequences. However, current models do not incorporate these critical feedbacks. We argue that in order to understand the dynamics of either system, Earth System Models must be coupled with Human System Models through bidirectional couplings representing the positive, negative, and delayed feedbacks that exist in the real systems. In particular, key Human System variables, such as demographics, inequality, economic growth, and migration, are not coupled with the Earth System but are instead driven by exogenous estimates, such as United Nations population projections. This makes current models likely to miss important feedbacks in the real Earth–Human system, especially those that may result in unexpected or counterintuitive outcomes, and thus requiring different policy interventions from current models. The importance and imminence of sustainability challenges, the dominant role of the Human System in the Earth System, and the essential roles the Earth System plays for the Human System, all call for collaboration of natural scientists, social scientists, and engineers in multidisciplinary research and modeling to develop coupled Earth–Human system models for devising effective science-based policies and measures to benefit current and future generations.
Directory of Open Access Journals (Sweden)
Y. Koyama
2011-04-01
Full Text Available This study assesses the advantages of using a coupled atmospheric-tracer transport model, comprising a global Eulerian model and a global Lagrangian particle dispersion model, to improve the reproducibility of tracer-gas variations affected by the near-field surface emissions and transport around observation sites. The ability to resolve variability in atmospheric composition on an hourly time-scale and a spatial scale of several kilometers would be beneficial for analyzing data from continuous ground-based monitoring and from upcoming space-based observations. The coupled model yields an increase in the horizontal resolution of transport and fluxes, and has been tested in regional-scale studies of atmospheric chemistry. By applying the Lagrangian component to the global domain, we extend this approach to the global scale, thereby enabling computationally efficient global inverse modeling and data assimilation. To validate the coupled model, we compare model-simulated CO_{2} concentrations with continuous observations at three sites: two operated by the National Oceanic and Atmospheric Administration, USA, and one operated by the National Institute for Environmental Studies, Japan. As the goal of this study is limited to introducing the new modeling approach, we selected a transport simulation at these three sites to demonstrate how the model may perform at various geographical areas. The coupled model provides improved agreement between modeled and observed CO_{2} concentrations in comparison to the Eulerian model. In an area where variability in CO_{2} concentration is dominated by a fossil fuel signal, the correlation coefficient between modeled and observed concentrations increases by between 0.05 to 0.1 from the original values of 0.5–0.6 achieved with the Eulerian model.
Petri, B; Stengl, M
2001-04-01
Increasing evidence indicates that the accessory medulla is the circadian pacemaker controlling locomotor activity rhythms in insects. A prominent group of neurons of this neuropil shows immunoreactivity to the peptide pigment-dispersing hormone (PDH). In Drosophila melanogaster, the PDH-immunoreactive (PDH-ir) lateral neurons, which also express the clock genes period and timeless, are assumed to be circadian pacemaker cells themselves. In other insects, such as Leucophaea maderae, a subset of apparently homologue PDH-ir cells is a candidate for the circadian coupling pathway of the bilaterally symmetric clocks. Although knowledge about molecular mechanisms of the circadian clockwork is increasing rapidly, very little is known about mechanisms of circadian coupling. The authors used a computer model, based on the molecular feedback loop of the clock genes in D. melanogaster, to test the hypothesis that release of PDH is involved in the coupling between bilaterally paired oscillators. They can show that a combination of all-delay- and all-advance-type interactions between two model oscillators matches best the experimental findings on mutual pacemaker coupling in L. maderae. The model predicts that PDH affects the phosphorylation rate of clock genes and that in addition to PDH, another neuroactive substance is involved in the coupling pathway, via an all-advance type of interaction. The model suggests that PDH and light pulses, represented by two distinct classes of phase response curves, have different targets in the oscillatory feedback loop and are, therefore, likely to act in separate input pathways to the clock.
Spronck, Bart; Martens, Esther G H J; Gommer, Erik D; van de Vosse, Frans N
2012-11-01
Cerebral blood flow regulation is based on a variety of different mechanisms, of which the relative regulatory role remains largely unknown. The cerebral regulatory system expresses two regulatory properties: cerebral autoregulation and neurovascular coupling. Since partly the same mechanisms play a role in cerebral autoregulation and neurovascular coupling, this study aimed to develop a physiologically based mathematical model of cerebral blood flow regulation combining these properties. A lumped parameter model of the P2 segment of the posterior cerebral artery and its distal vessels was constructed. Blood flow regulation is exerted at the arteriolar level by vascular smooth muscle and implements myogenic, shear stress based, neurogenic, and metabolic mechanisms. In eight healthy subjects, cerebral autoregulation and neurovascular coupling were challenged by squat-stand maneuvers and visual stimulation using a checkerboard pattern, respectively. Cerebral blood flow velocity was measured using transcranial Doppler, whereas blood pressure was measured by finger volume clamping. In seven subjects, the model proposed fits autoregulation and neurovascular coupling measurement data well. Myogenic regulation is found to dominate the autoregulatory response. Neurogenic regulation, although only implemented as a first-order mechanism, describes neurovascular coupling responses to a great extent. It is concluded that our single, integrated model of cerebral blood flow control may be used to identify the main mechanisms affecting cerebral blood flow regulation in individual subjects.
Higgs boson couplings in multi-doublet models with natural flavour conservation
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Kei Yagyu
2016-12-01
Full Text Available We investigate the deviation in the couplings of the standard model (SM like Higgs boson (h with a mass of 125 GeV from the prediction of the SM in multi-doublet models within the framework where flavour changing neutral currents at the tree level are naturally forbidden. After we present the general expressions for the modified gauge and Yukawa couplings for h, we show the correlation between the deviation in the Yukawa coupling for the tau lepton hτ+τ− and that for the bottom quark hbb¯ under the assumption of a non-zero deviation in the hVV (V=W,Z couplings in two Higgs doublet models (2HDMs and three Higgs doublet models (3HDMs as simple examples. We clarify the possible allowed prediction of the deviations in the 3HDMs which cannot be explained in the 2HDMs even taking into account the one-loop electroweak corrections to the Yukawa coupling.
Stability of the interhemispheric thermohaline circulation in a coupled box model
Stone, Peter H.; Krasovskiy, Yuriy P.
1999-07-01
The coupled atmosphere-ocean box model of the interhemispheric thermohaline circulation (THC) formulated by Scott et al. [Scott, J.R., Marotzke, J., Stone, P.H., 1999. Interhemispheric THC in a coupled box model. J. Phys. Oceanogr., 29, 351-365.] is solved analytically, by introducing the approximation that the time variations of salinity in the ocean are much slower than the time variations in the temperature. The analytic solution shows that there is an unstable limit cycle near the bifurcation where the flow becomes unstable, as suggested by Scott et al.'s numerical solutions. The solution also leads to an analytic expression for the conditions under which the instability discovered by Scott et al. sets in, which is more general than that found by Scott et al. In particular, it includes the effect of coupling the THC to the atmospheric meridional transports of heat and moisture. It shows that the stability of THC is much more sensitive to the representation of the atmospheric heat transport, i.e., to how it depends on the meridional temperature gradient, than it is in hemispheric models. In particular, it shows that interhemispheric ocean models that use mixed boundary conditions, or couple the ocean to a diffusive representation of the atmospheric heat transport, are less susceptible to this kind of instability than when the ocean is coupled to a representation of the atmospheric meridional heat transport which is more sensitive to the meridional temperature gradient, as is implied by observations and theory.
Shi, Shuangxia; Su, Zhu; Jin, Guoyong; Liu, Zhigang
2018-01-01
This paper is concerned with the modeling and solution method of a three-dimensional (3D) coupled acoustic system comprising a partially opened cavity coupled with a flexible plate and an exterior field of semi-infinite size, which is ubiquitously encountered in architectural acoustics and is a reasonable representation of many engineering occasions. A general solution method is presented to predict the dynamic behaviors of the three-dimensional (3D) acoustic coupled system, in which the displacement of the plate and the sound pressure in the cavity are respectively constructed in the form of the two-dimensional and three-dimensional modified Fourier series with several auxiliary functions introduced to ensure the uniform convergence of the solution over the entire solution domain. The effect of the opening is taken into account via the work done by the sound pressure acting at the coupling aperture that is contributed from the vibration of particles on the acoustic coupling interface and on the structural-acoustic coupling interface. Both the acoustic coupling between finite cavity and exterior field and the structural-acoustic coupling between flexible plate and interior acoustic field are considered in the vibro-acoustic modeling of the three-dimensional acoustic coupled acoustic system. The dynamic responses of the coupled structural-acoustic system are obtained using the Rayleigh-Ritz procedure based on the energy expressions for the coupled system. The accuracy and effectiveness of the proposed method are validated through numerical examples and comparison with results obtained by the boundary element analysis. Furthermore, the influence of the opening and the cavity volume on the acoustic behaviors of opened cavity system is studied.
Modeling on thermally induced coupled micro-motions of satellite with complex flexible appendages
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Zhicheng Zhou
2015-06-01
Full Text Available To describe the characteristics of thermally induced coupled micro-motions more exactly, a numerical model is proposed for a satellite system consisting of a rigid body and the complex appendages. The coupled governing equations including the effects of transient temperature differences are formulated within the framework of the Lagrangian Method based on the finite element models of flexible structures. Meanwhile, the problem of coupling between attitude motions of rigid body and vibrations of flexible attachments are addressed with explicit expressions. Thermally induced micro-motions are examined in detail for a simple satellite with a large solar panel under the disturbance of thermal environment from earth shadow to sunlight area in the earth orbit. The results show that the thermal–mechanical performances of an on-orbit satellite can be well predicted by the proposed finite element model.
Arm motion coupling during locomotion-like actions: An experimental study and a dynamic model
Shapkova, E.Yu; Terekhov, A.V.; Latash, M.L.
2010-01-01
We studied the coordination of arm movements in standing persons who performed an out-of-phase arm-swinging task while stepping in place or while standing. The subjects were instructed to stop one of the arms in response to an auditory signal while trying to keep the rest of the movement pattern unchanged. A significant increase was observed in the amplitude of the arm that continued swinging under both the stepping and standing conditions. This increase was similar between the right and left arms. A dynamic model was developed including two coupled non-linear van der Pol oscillators. We assumed that stopping an arm did not eliminate the coupling but introduced a new constraint. Within the model, superposition of two factors, a command to stop the ongoing movement of one arm and the coupling between the two oscillators, has been able to account for the observed effects. The model makes predictions for future experiments. PMID:21628725
Meng, Deshan; Wang, Xueqian; Xu, Wenfu; Liang, Bin
2017-05-01
For a space robot with flexible appendages, vibrations of flexible structure can be easily excited during both orbit and/or attitude maneuvers of the base and the operation of the manipulators. Hence, the pose (position and attitude) of the manipulator's end-effector will greatly deviate from the desired values, and furthermore, the motion of the manipulator will trigger and exacerbate vibrations of flexible appendages. Given lack of the atmospheric damping in orbit, the vibrations will last for quite a while and cause the on-orbital tasks to fail. We derived the rigid-flexible coupling dynamics of a space robot system with flexible appendages and established a coupling model between the flexible base and the space manipulator. A specific index was defined to measure the coupling degree between the flexible motion of the appendages and the rigid motion of the end-effector. Then, we analyzed the dynamic coupling for different conditions, such as modal displacements, joint angles (manipulator configuration), and mass properties. Moreover, the coupling map was adopted and drawn to represent the coupling motion. Based on this map, a trajectory planning method was addressed to suppress structure vibration. Finally, simulation studies of typical cases were performed, which verified the proposed models and method. This work provides a theoretic basis for the system design, performance evaluation, trajectory planning, and control of such space robots.
Montazeri, Allahyar; Taylor, C. James
2017-10-01
This article addresses the coupling of acoustic secondary sources in a confined space in a sound field reduction framework. By considering the coupling of sources in a rectangular enclosure, the set of coupled equations governing its acoustical behavior are solved. The model obtained in this way is used to analyze the behavior of multi-input multi-output (MIMO) active sound field control (ASC) systems, where the coupling of sources cannot be neglected. In particular, the article develops the analytical results to analyze the effect of coupling of an array of secondary sources on the sound pressure levels inside an enclosure, when an array of microphones is used to capture the acoustic characteristics of the enclosure. The results are supported by extensive numerical simulations showing how coupling of loudspeakers through acoustic modes of the enclosure will change the strength and hence the driving voltage signal applied to the secondary loudspeakers. The practical significance of this model is to provide a better insight on the performance of the sound reproduction/reduction systems in confined spaces when an array of loudspeakers and microphones are placed in a fraction of wavelength of the excitation signal to reduce/reproduce the sound field. This is of particular importance because the interaction of different sources affects their radiation impedance depending on the electromechanical properties of the loudspeakers.
Directory of Open Access Journals (Sweden)
S. Sippel
2017-05-01
Full Text Available The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land–atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land–atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T and evapotranspiration (ET benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land–atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5 archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T–ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T–ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand
Sippel, Sebastian; Zscheischler, Jakob; Mahecha, Miguel D.; Orth, Rene; Reichstein, Markus; Vogel, Martha; Seneviratne, Sonia I.
2017-05-01
The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land-atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land-atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T) and evapotranspiration (ET) benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land-atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5) archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET) are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T-ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T-ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand, the differences between projected
A new adaptive data transfer library for model coupling
Zhang, Cheng; Liu, Li; Yang, Guangwen; Li, Ruizhe; Wang, Bin
2016-06-01
Data transfer means transferring data fields from a sender to a receiver. It is a fundamental and frequently used operation of a coupler. Most versions of state-of-the-art couplers currently use an implementation based on the point-to-point (P2P) communication of the message passing interface (MPI) (referred to as "P2P implementation" hereafter). In this paper, we reveal the drawbacks of the P2P implementation when the parallel decompositions of the sender and the receiver are different, including low communication bandwidth due to small message size, variable and high number of MPI messages, as well as network contention. To overcome these drawbacks, we propose a butterfly implementation for data transfer. Although the butterfly implementation outperforms the P2P implementation in many cases, it degrades the performance when the sender and the receiver have similar parallel decompositions or when the number of processes used for running models is small. To ensure data transfer with optimal performance, we design and implement an adaptive data transfer library that combines the advantages of both butterfly implementation and P2P implementation. As the adaptive data transfer library automatically uses the best implementation for data transfer, it outperforms the P2P implementation in many cases while it does not decrease the performance in any cases. Now, the adaptive data transfer library is open to the public and has been imported into the C-Coupler1 coupler for performance improvement of data transfer. We believe that other couplers can also benefit from this.
Advances in Modeling of Coupled Hydrologic-Socioeconomic Systems
Amadio, Mattia; Mysiak, Jaroslav; Pecora, Silvano; Agnetti, Alberto
2013-04-01
River flooding is the most common natural disaster in Europe, causing deaths and huge amount of economic losses. Disastrous flood events are often related to extreme meteorological conditions; therefore, climate change is expected to have an important influence over the intensity and frequency of major floods. While approximated large-scale assessments of flood risk scenarios have been carried out, the knowledge of the effects at smaller scales is poor or incomplete, with few localized studies. Also, the methods are still coarse and uneven. The approach of this study starts from the definition of the risk paradigm and the elaboration of local climatic scenarios to track a methodology aimed at elaborating and combining the three elements concurring to the determination of risk: hydrological hazard, value exposure and vulnerability. First, hydrological hazard scenarios are provided by hydrological and hydrodynamic models, used in to a flood forecasting system capable to define "what-if" scenario in a flexible way. These results are then integrated with land-use data (exposure) and depth-damage functions (vulnerability) in a GIS environment, to assess the final risk value (potential flood damage) and visualize it in form of risk maps. In this paper results from a pilot study in the Polesine area are presented, where four simulated levee breach scenarios are compared. The outcomes of the analysis may be instrumental to authorities to increase the knowledge of possible direct losses and guide decision making and planning processes also. As future perspective, the employed methodology can also be extended at the basin scale through integration with the existent flood warning system to gain a real-time estimate of floods direct costs.
The coupled atmosphere–chemistry–ocean model SOCOL-MPIOM
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S. Muthers
2014-09-01
Full Text Available The newly developed atmosphere–ocean–chemistry–climate model SOCOL-MPIOM is presented by demonstrating the influence of chemistry–climate interactions on the climate state and the variability. Therefore, we compare pre-industrial control simulations with (CHEM and without (NOCHEM interactive chemistry. In general, the influence of the chemistry on the mean state and the variability is small and mainly restricted to the stratosphere and mesosphere. The atmospheric dynamics mainly differ in polar regions, with slightly stronger polar vortices in the austral and boreal winter, respectively. The strengthening of the vortex is related to larger stratospheric temperature gradients, which are attributed to a parameterisation of the absorption of ozone and oxygen in different wavelength intervals, which is considered in the version with interactive chemistry only. A second reason for the temperature differences between CHEM and NOCHEM is related to diurnal variations in the ozone concentrations in the higher atmosphere, which are missing in NOCHEM. Furthermore, stratospheric water vapour concentrations substantially differ between the two experiments, but their effect on temperature is small. In both setups, the simulated intensity and variability of the northern polar vortex is inside the range of present-day observations. Additionally, the performance of SOCOL-MPIOM under changing external forcings is assessed for the period 1600–2000 using an ensemble of simulations. In the industrial period from 1850 onward SOCOL-MPIOM overestimates the global mean surface air temperature increase in comparison to observational data sets. Sensitivity simulations show that this overestimation can be attributed to a combination of factors: the solar forcing reconstruction, the simulated ozone changes, and incomplete aerosol effects and land use changes.
Coupling groundwater, vegetation and atmosphere processes: a comparison of two integrated models
Sulis, M.; Williams, J. L.; Shrestha, P.; Maxwell, R. M.; Masbou, M.; Simmer, C.
2012-12-01
The correct modelling of the mutual response to and feedback between atmospheric, hydrological, and ecological processes is an important prerequisite for accurate climate/meteorological projection, environmental protection, and water management. As such, numerical models based on a detailed representation of both groundwater and atmospheric dynamics have gained increasing attention within the scientific community. In this study, we compare two integrated systems that dynamically simulate soil-vegetation-atmosphere interactions. One system is the combination of the Weather Research and Forecasting (WRF) atmospheric model coupled with the three-dimensional variably saturated subsurface ParFlow model. Both sub-models are internally coupled in an explicit, operator-splitting manner via the Noah land surface scheme. The second system consists of the regional climate and weather forecast model COSMO coupled also with ParFlow but via the Community Land Model (CLM). In this second system the external OASIS coupler is used to pass relevant fluxes and state variables between these three components via the MPI parallel communications protocol. The comparison on how interactions are simulated and how different processes are integrated/coupled is carried out by selecting a set of test cases. These tests involve a flat domain with idealized initial and boundary conditions, as well as simulations over the Rur catchment in Germany based upon equilibrium initial conditions for the subsurface and realistic atmospheric conditions at the boundaries. We explore and explain the differences in model response, and we discuss the pros and cons of the two approaches by emphasizing the role played by factors such as temporal subcycling and coupling frequency between model components.
Wavelet coupled MARS and M5 Model Tree approaches for groundwater level forecasting
Rezaie-balf, Mohammad; Naganna, Sujay Raghavendra; Ghaemi, Alireza; Deka, Paresh Chandra
2017-10-01
In this study, two different machine learning models, Multivariate Adaptive Regression Splines (MARS) and M5 Model Trees (MT) have been applied to simulate the groundwater level (GWL) fluctuations of three shallow open wells within diverse unconfined aquifers. The Wavelet coupled MARS and MT hybrid models were developed in an attempt to further increase the GWL forecast accuracy. The Discrete Wavelet Transform (DWT) which is particularly effective in dealing with non-stationary time-series data was employed to decompose the input time series into various sub-series components. Historical data of 10 years (August-1996 to July-2006) comprising monthly groundwater level, rainfall, and temperature were used to calibrate and validate the models. The models were calibrated and tested for one, three and six months ahead forecast horizons. The wavelet coupled MARS and MT models were compared with their simple counterpart using standard statistical performance evaluation measures such as Root Mean Square Error (RMSE), Normalized Nash-Sutcliffe Efficiency (NNSE) and Coefficient of Determination (R2) . The wavelet coupled MARS and MT models developed using multi-scale input data performed better compared to their simple counterpart and the forecast accuracy of W-MARS models were superior to that of W-MT models. Specifically, the DWT offered a better discrimination of non-linear and non-stationary trends that were present at various scales in the time series of the input variables thus crafting the W-MARS models to provide more accurate GWL forecasts.
Microtubule dynamic instability: A new model with coupled GTP hydrolysis and multistep catastrophe
Bowne-Anderson, Hugo; Zanic, Marija; Kauer, Monika; Howard, Jonathon
2013-01-01
A key question in understanding microtubule dynamics is how GTP hydrolysis leads to catastrophe, the switch from slow growth to rapid shrinkage. We first provide a review of the experimental and modeling literature, and then present a new model of microtubule dynamics. We demonstrate that vectorial, random, and coupled hydrolysis mechanisms are not consistent with the dependence of catastrophe on tubulin concentration and show that, although single-protofilament models can explain many features of dynamics, they do not describe catastrophe as a multistep process. Finally, we present a new combined (coupled plus random hydrolysis) multiple-protofilament model that is a simple, analytically solvable generalization of a single-protofilament model. This model accounts for the observed lifetimes of growing microtubules, the delay to catastrophe following dilution and describes catastrophe as a multistep process. PMID:23532586
A systematic investigation of climate drift in a global coupled model
Energy Technology Data Exchange (ETDEWEB)
Moore, A.M. [Bureau of Meteorology Research Centre, Melbourne, Victoria (Australia); Gordon, H.B. [CSIRO, Mordialloc, Victoria (Australia). Division of Atmospheric Research
1994-12-31
Climate drift is a common and serious problem in most state-of-the-art coupled atmosphere ocean-sea-ice models. The authors consider the nature of climate drift in such a model, and in particular address the question of whether or not climate drift is inherent to the model, or whether the drift can be averted by a suitable choice of initial conditions or coupling procedure. Several experiments were performed which were designed to assess the impact of different coupling methodologies and changes in the initial conditions of the component models on the climate drift of the system. The results of their experiments indicate that climate drift is a problem inherent to the coupled model which is associated with incompatibilities in the surface fluxes required by the component models to maintain realistic climatologies. The authors conclude that climate drift can be averted only if the parameterizations of certain important physical processes are improved, which should have the effect of reducing or eliminating these incompatibilities
Investigation of acoustically coupled enclosures using a diffusion-equation model.
Xiang, Ning; Jing, Yun; Bockman, Alexander C
2009-09-01
Recent application of coupled-room systems in performing arts spaces has prompted active research on sound fields in these complex geometries. This paper applies a diffusion-equation model to the study of acoustics in coupled-rooms. Acoustical measurements are conducted on a scale-model of two coupled-rooms. Using the diffusion model and the experimental results the current work conducts in-depth investigations on sound pressure level distributions, providing further evidence supporting the valid application of the diffusion-equation model. Analysis of the results within the Bayesian framework allows for quantification of the double-slope characteristics of sound-energy decays obtained from the diffusion-equation numerical modeling and the experimental measurements. In particular, Bayesian decay analysis confirms sound-energy flux modeling predictions that time-dependent sound-energy flows in coupled-room systems experience feedback in the form of energy flow-direction change across the aperture connecting the two rooms in cases where the dependent room is more reverberant than the source room.
The feasibility of modelling coupled processes in safety analysis of spent nuclear fuel disposal
Energy Technology Data Exchange (ETDEWEB)
Rasilainen, K. [VTT Energy, Espoo (Finland); Luukkonen, A.; Niemi, A.; Poellae, J. [VTT Communities and Infrastructure, Espoo (Finland); Olin, M. [VTT Chemical Technology, Espoo (Finland)
1999-07-01
The potential of applying coupled modelling in the Finnish safety analysis programme has been reviewed. The study focused on the migration of radionuclides escaping from a spent fuel repository planned to be excavated in fractured bedrock. Two effects that can trigger various couplings in and around a spent fuel repository in Finland were studied in detail; namely heat generation in the spent fuel and the presence of deep, saline groundwaters. The latter have been observed in coastal areas. A systematic survey of the requirements of coupled modelling identified features that render such migration calculations a challenging task. In groundwater flow modelling there appears to be wide ranging uncertainty related to conceptualisation of flow systems and to the corresponding input data. In terms of migration related chemistry there appear to be large gaps in the underlying thermodynamic database for geochemical systems. Rock mechanical predictions are heavily dependent on knowing the location, structure and properties of dominant fractures; information which is extremely difficult to obtain. Conduction and convection of heat is understood well in principle. On the basis of this review, it appears that coupled migration modelling may not yet be at the stage of development that would allow its use as a standard modelling tool in performance assessments. However, a firmer basis for the conclusions reached can only be obtained after a systematic modelling exercise on a relevant and real migration problem has been carried out. (orig.)
Untoro, T.; Viridi, S.; Suprijanto; Ekawati, E.
2017-07-01
In our previous work, we have developed a mechanical coupling for energy harvester from vibration source. This energy harvester uses piezoelectric with additional cantilever beam and permanent magnets. Our work proposed alternative scheme of mechanical coupling for tune the vibration input into resonant frequency of piezoelectric. Based on the experiment, correlation between the length of cantilever beam and the output power also evaluated. In this paper, we try to modelling our work into mathematical model and apply it to some case study. For example application, we apply our energy harvester system to generate electrical energy to enlighten the street. The human footsteps can be used as vibration source to generate electrical energy.
Modeling dynamically coupled fluid-duct systems with finite line elements
Saxon, J. B.
1994-01-01
Structural analysis of piping systems, especially dynamic analysis, typically considers the duct structure and the contained fluid column separately. Coupling of these two systems, however, forms a new dynamic system with characteristics not necessarily described by the superposition of the two component system's characteristics. Methods for modeling the two coupled components simultaneously using finite line elements are presented. Techniques for general duct intersections, area or direction changes, long radius bends, hydraulic losses, and hydraulic impedances are discussed. An example problem and results involving time transients are presented. Additionally, a program to enhance post-processing of line element models is discussed.
Modeling Coupled THM Processes and Brine Migration in Salt at High Temperatures
Energy Technology Data Exchange (ETDEWEB)
Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Blanco-Martin, Laura [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Molins, Sergi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Trebotich, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2015-09-01
In this report, we present FY2015 progress by Lawrence Berkeley National Laboratory (LBNL) related to modeling of coupled thermal-hydrological-mechanical-chemical (THMC) processes in salt and their effect on brine migration at high temperatures. This is a combined milestone report related to milestone Salt R&D Milestone “Modeling Coupled THM Processes and Brine Migration in Salt at High Temperatures” (M3FT-15LB0818012) and the Salt Field Testing Milestone (M3FT-15LB0819022) to support the overall objectives of the salt field test planning.
Error analysis for momentum conservation in Atomic-Continuum Coupled Model
Yang, Yantao; Cui, Junzhi; Han, Tiansi
2016-08-01
Atomic-Continuum Coupled Model (ACCM) is a multiscale computation model proposed by Xiang et al. (in IOP conference series materials science and engineering, 2010), which is used to study and simulate dynamics and thermal-mechanical coupling behavior of crystal materials, especially metallic crystals. In this paper, we construct a set of interpolation basis functions for the common BCC and FCC lattices, respectively, implementing the computation of ACCM. Based on this interpolation approximation, we give a rigorous mathematical analysis of the error of momentum conservation equation introduced by ACCM, and derive a sequence of inequalities that bound the error. Numerical experiment is carried out to verify our result.
Energy Technology Data Exchange (ETDEWEB)
Saravanan, Ramalingam [Texas A& M University
2011-10-30
During the course of this project, we have accomplished the following: a) Carried out studies of climate changes in the past using a hierarchy of intermediate coupled models (Chang et al., 2008; Wan et al 2009; Wen et al., 2010a,b) b) Completed the development of a Coupled Regional Climate Model (CRCM; Patricola et al., 2011a,b) c) Carried out studies testing hypotheses testing the origin of systematic errors in the CRCM (Patricola et al., 2011a,b) d) Carried out studies of the impact of air-sea interaction on hurricanes, in the context of barrier layer interactions (Balaguru et al)
Moreno Chaparro, Nicolas
2013-06-01
A variational multi scale approach to model blood flow through arteries is proposed. A finite element discretization to represent the coarse scales (macro size), is coupled to smoothed dissipative particle dynamics that captures the fine scale features (micro scale). Blood is assumed to be incompressible, and flow is described through the Navier Stokes equation. The proposed cou- pling is tested with two benchmark problems, in fully coupled systems. Further refinements of the model can be incorporated in order to explicitly include blood constituents and non-Newtonian behavior. The suggested algorithm can be used with any particle-based method able to solve the Navier-Stokes equation.
De La Lama, Luisa Batthyany; De La Lama, Luis; Wittgenstein, Ariana
2012-01-01
This article presents the integrative soul mates relationship development model, which provides the helping professionals with a conceptual map for couples' relationship development from dating, to intimacy, to soul mating, and long-term flourishing. This model is informed by a holistic, a developmental, and a positive psychology conceptualization…
Ocean-Wave Coupled Modeling in COAMPS-TC: A Study of Hurricane Ivan (2004)
2013-08-15
input of the Stokes Drift Current ( SDC ) calculated from the SWAN wave spectra to NCOM, is examined. The models indicate that the SDC was on the order...of 10 -25% of the near-surface Eulerian current during Ivan. Recent studies of the importance of the SDC and the resulting Langmuir turbulence on...model coupling, which included the input of the Stokes Drift Current ( SDC ) calculated from the SWAN wave spectra to NCOM, is examined. The models indi
Transmission line model for coupled rectangular double split‐ring resonators
DEFF Research Database (Denmark)
Yan, Lei; Tang, Meng; Krozer, Viktor
2011-01-01
In this work, a model based on a coupled transmission line formulation is developed for microstrip rectangular double split‐ring resonators (DSRRs). This model allows using the physical dimensions of the DSRRs as an input avoiding commonly used extraction of equivalent parameters. The model...... DSRRs, which allows for an accurate modeling of densely packed multiresonator structures. The model is verified by comparison with measured DSRRs‐loaded microstrip line performance. The developed model can be effectively used to save computation resources associated with full wave electromagnetic...
Computational implementation of the multi-mechanism deformation coupled fracture model for salt
Energy Technology Data Exchange (ETDEWEB)
Koteras, J.R.; Munson, D.E.
1996-05-01
The Multi-Mechanism Deformation (M-D) model for creep in rock salt has been used in three-dimensional computations for the Waste Isolation Pilot Plant (WIPP), a potential waste, repository. These computational studies are relied upon to make key predictions about long-term behavior of the repository. Recently, the M-D model was extended to include creep-induced damage. The extended model, the Multi-Mechanism Deformation Coupled Fracture (MDCF) model, is considerably more complicated than the M-D model and required a different technology from that of the M-D model for a computational implementation.
Interlayer-coupling energy of magnetic trilayers in a one-band tight-binding model
Li, Lie-Ming; Pu, Fu-Cho
1995-02-01
The general formula of exchange coupling between transition-metal ferromagnetic layers spaced by a nonferromagnetic transition-metal layer with flat interfaces is given within a one-band tight-binding model for a simple cubic lattice, which determines self-consistently the Fermi level so as to take account of the dependence of the Fermi level on the magnetic configuration and thicknesses of layers, for thin magnetic trilayers. For large exchange splitting and thickness of ferromagnetic layers, assuming the minority-spin energy bands in the ferromagnets matches that of the spacer, we made detailed calculations to obtain both the analytic expression of interlayer exchange coupling energies and its simple asymptotic expression for large spacer thickness, which is accurate enough even for spacer thickness N=6. In some reasonable range of parameter, for smaller spacer thickness, intrinsic biquadratic coupling given by our theory is strong enough to be a dominant mechanism of noncolinear aligning of magnetization direction of two ferromagnetic layers, which plays a similar role as that of the magnetostatic interaction induced by interfacial roughness. The situation still holds even for large exchange splitting, different from existing theoretical works based on the free-electron model. Our results imply that intrinsic biquadratic coupling is more sensitive to the models chosen than bilinear coupling.
On the dependence of hindcast skill on ocean thermodynamics in a coupled ocean-atmosphere model
Energy Technology Data Exchange (ETDEWEB)
Kleeman, R. (Bureau of Meteorology Research Centre, Melbourne (Australia))
1993-11-01
Three different mechanisms for the generation of ENSO SST anomalies within a simplified tropical Pacific Ocean model are examined: thermocline depth changes, Ekman-induced upwelling anomalies, and zonal advection changes. The effect of varying the relative influence of these terms on the realism of tropical pacific coupled models is analyzed. The principal tool used to assess such realism is hindcast skill, with forced ocean and oscillatory behavior also being examined. Of the mechanisms considered, thermocline perturbations are shown to be crucially important for high coupled-model hindcast skills. Furthermore, it is concluded that the realism of the model (as measured by hindcast skill) deteriorates markedly when the influence on SST of Ekman upwelling becomes greater than a small fraction of the thermocline influence. This provides strong evidence for the hypothesis that Ekman upwelling anomalies (which are essentially a local response to wind stress anomalies) have only a small influence on the creation of real world SST anomalies. The implications of this latter point for coupled models involving ocean general circulation models is briefly discussed. It is also demonstrated that western boundary reflections provide a vital role by means of a negative feedback in ensuring realistic performance. The hindcast skill (as measured by NINO3 anomaly correlation) demonstrated by a model involving only the thermocline mechanism can be tuned to exceed that of the benchmark Cane and Zebiak model for hindcast lags up to 7 months (from 7 to 12 months the model skills are roughly equal). 47 refs., 32 figs.
Coupled 0D-1D CFD Modeling of Right Heart and Pulmonary Artery Morphometry Tree
Dong, Melody; Yang, Weiguang; Feinstein, Jeffrey A.; Marsden, Alison
2017-11-01
Pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary artery (PA) pressure and remodeling of the distal PAs resulting in right ventricular (RV) dysfunction and failure. It is hypothesized that patients with untreated ventricular septal defects (VSD) may develop PAH due to elevated flows and pressures in the PAs. Wall shear stress (WSS), due to elevated flows, and circumferential stress, due to elevated pressures, are known to play a role in vascular mechanobiology. Thus, simulating VSD hemodynamics and wall mechanics may facilitate our understanding of mechanical stimuli leading to PAH initiation and progression. Although 3D CFD models can capture detailed hemodynamics in the proximal PAs, they cannot easily model hemodynamics and wave propagation in the distal PAs, where remodeling occurs. To improve current PA models, we will present a new method that couples distal PA hemodynamics with RV function. Our model couples a 0D lumped parameter model of the RV to a 1D model of the PA tree, based on human PA morphometry data, to characterize RV performance and WSS changes in the PA tree. We will compare a VSD 0D-1D model and a 0D-3D model coupled to a mathematical morphometry tree model to quantify WSS in the entire PA vascular tree.
Drobny, Jon; Curreli, Davide; Ruzic, David; Lasa, Ane; Green, David; Canik, John; Younkin, Tim; Blondel, Sophie; Wirth, Brian
2017-10-01
Surface roughness greatly impacts material erosion, and thus plays an important role in Plasma-Surface Interactions. Developing strategies for efficiently introducing rough surfaces into ion-solid interaction codes will be an important step towards whole-device modeling of plasma devices and future fusion reactors such as ITER. Fractal TRIDYN (F-TRIDYN) is an upgraded version of the Monte Carlo, BCA program TRIDYN developed for this purpose that includes an explicit fractal model of surface roughness and extended input and output options for file-based code coupling. Code coupling with both plasma and material codes has been achieved and allows for multi-scale, whole-device modeling of plasma experiments. These code coupling results will be presented. F-TRIDYN has been further upgraded with an alternative, statistical model of surface roughness. The statistical model is significantly faster than and compares favorably to the fractal model. Additionally, the statistical model compares well to alternative computational surface roughness models and experiments. Theoretical links between the fractal and statistical models are made, and further connections to experimental measurements of surface roughness are explored. This work was supported by the PSI-SciDAC Project funded by the U.S. Department of Energy through contract DOE-DE-SC0008658.
Ma, Jun; Liu, Lei; Ge, Sai; Xue, Qiang; Li, Jiangshan; Wan, Yong; Hui, Xinminnan
2018-02-01
A quantitative description of aerobic waste degradation is important in evaluating landfill waste stability and economic management. This research aimed to develop a coupling model to predict the degree of aerobic waste degradation. On the basis of the first-order kinetic equation and the law of conservation of mass, we first developed the coupling model of aerobic waste degradation that considered temperature, initial moisture content and air injection volume to simulate and predict the chemical oxygen demand in the leachate. Three different laboratory experiments on aerobic waste degradation were simulated to test the model applicability. Parameter sensitivity analyses were conducted to evaluate the reliability of parameters. The coupling model can simulate aerobic waste degradation, and the obtained simulation agreed with the corresponding results of the experiment. Comparison of the experiment and simulation demonstrated that the coupling model is a new approach to predict aerobic waste degradation and can be considered as the basis for selecting the economic air injection volume and appropriate management in the future.
A comparison of iterative methods for a model coupled system of elliptic equations
Energy Technology Data Exchange (ETDEWEB)
Donato, J.M.
1993-08-01
Many interesting areas of current industry work deal with non-linear coupled systems of partial differential equations. We examine iterative methods for the solution of a model two-dimensional coupled system based on a linearized form of the two carrier drift-diffusion equations from semiconductor modeling. Discretizing this model system yields a large non-symmetric indefinite sparse matrix. To solve the model system various point and block methods, including the hybrid iterative method Alternate Block Factorization (ABF), are applied. We also employ GMRES with various preconditioners, including block and point incomplete LU (ILU) factorizations. The performance of these methods is compared. It is seen that the preferred ordering of the grid variables and the choice of iterative method are dependent upon the magnitudes of the coupling parameters. For this model, ABF is the most robust of the non-accelerated iterative methods. Among the preconditioners employed with GMRES, the blocked ``by grid point`` version of both the ILU and MILU preconditioners are the most robust and the most time efficient over the wide range of parameter values tested. This information may aid in the choice of iterative methods and preconditioners for solving more complicated, yet analogous, coupled systems.
A Thermo-Hygro-Coupled Model for Chloride Penetration in Concrete Structures
Directory of Open Access Journals (Sweden)
Nattapong Damrongwiriyanupap
2015-01-01
Full Text Available Corrosion damage due to chloride attack is one of the most concerning issues for long term durability of reinforced concrete structures. By developing the reliable mathematical model of chloride penetration into concrete structures, it can help structural engineers and management agencies with predicting the service life of reinforced concrete structures in order to effectively schedule the maintenance, repair, and rehabilitation program. This paper presents a theoretical and computational model for chloride diffusion in concrete structures. The governing equations are taking into account the coupled transport process of chloride ions, moisture, and temperature. This represents the actual condition of concrete structures which are always found in nonsaturated and nonisothermal conditions. The fully coupled effects among chloride, moisture, and heat diffusion are considered and included in the model. The coupling parameters evaluated based on the available material models and test data are proposed and explicitly incorporated in the governing equations. The numerical analysis of coupled transport equations is performed using the finite element method. The model is validated by comparing the numerical results against the available experimental data and a good agreement is observed.
Modeling of Interfilament Coupling Currents and Their Effect on Magnet Quench Protection
Ravaioli, E; Chlachidze, G; Maciejewski, M; Sabbi, G; Stoynev, S E; Verweij, A
2016-01-01
Variations in the transport current of a superconducting magnet cause several types of transitory losses. Due to its relatively short time constant, usually of the order of a few tens of milliseconds, interfilament coupling loss can have a significant effect on the coil protection against overheating after a quench. This loss is deposited in the strands and can facilitate a more homogeneous transition to the normal state of the coil turns. Furthermore, the presence of local interfilament coupling currents reduces the magnet's differential inductance, which in turn provokes a faster discharge of the transport current. The lumped-element dynamic electrothermal model of a superconducting magnet has been developed to reproduce these effects. Simulations are compared to experimental electrical transients and found in good agreement. After its validation, the model can be used for predicting the performance of quench protection systems based on energy extraction, quench heaters, the newly developed coupling-loss-in...
Antonelli, Cristian; Mecozzi, Antonio; Li, Wangzhe; Coldren, Larry A.
2016-05-01
We present a model for multi-wavelength mixing in semiconductor optical amplifiers (SOAs) based on coupled-mode equations. The proposed model applies to all kinds of SOA structures, takes into account the longitudinal dependence of carrier density caused by saturation, it accommodates an arbitrary functional dependencies of the material gain and carrier recombination rate on the local value of carrier density, and is computationally more efficient by orders of magnitude as compared with the standard full model based on space-time equations. We apply the coupled-mode equations model to a recently demonstrated phase-sensitive amplifier based on an integrated SOA and prove its results to be consistent with the experimental data. The accuracy of the proposed model is certified by means of a meticulous comparison with the results obtained by integrating the space-time equations.
Solar system tests for realistic f( T) models with non-minimal torsion-matter coupling
Lin, Rui-Hui; Zhai, Xiang-Hua; Li, Xin-Zhou
2017-08-01
In the previous paper, we have constructed two f( T) models with non-minimal torsion-matter coupling extension, which are successful in describing the evolution history of the Universe including the radiation-dominated era, the matter-dominated era, and the present accelerating expansion. Meantime, the significant advantage of these models is that they could avoid the cosmological constant problem of Λ CDM. However, the non-minimal coupling between matter and torsion will affect the tests of the Solar system. In this paper, we study the effects of the Solar system in these models, including the gravitation redshift, geodetic effect and perihelion precession. We find that Model I can pass all three of the Solar system tests. For Model II, the parameter is constrained by the uncertainties of the planets' estimated perihelion precessions.
Solar system tests for realistic $f(T)$ models with nonminimal torsion-matter coupling
Lin, Rui-Hui; Li, Xin-Zhou
2016-01-01
In the previous paper, we have constructed two $f(T)$ models with nonminimal torsion-matter coupling extension, which are successful in describing the evolution history of the Universe including the radiation-dominated era, the matter-dominated era, and the present accelerating expansion. Meantime, the significant advantage of these models is that they could avoid the cosmological constant problem of $\\Lambda$CDM. However, the nonminimal coupling between matter and torsion will affect the tests of Solar system. In this paper, we study the effects of Solar system in these models, including the gravitation redshift, geodetic effect and perihelion preccesion. We find that Model I can pass all three of the Solar system tests. For Model II, the parameter is constrained by the measure of the perihelion precession of Mercury.
Sensitivity testing practice on pre-processing parameters in hard and soft coupled modeling
Directory of Open Access Journals (Sweden)
Z. Ignaszak
2010-01-01
Full Text Available This paper pays attention to the problem of practical applicability of coupled modeling with the use of hard and soft models types and necessity of adapted to that models data base possession. The data base tests results for cylindrical 30 mm diameter casting made of AlSi7Mg alloy were presented. In simulation tests that were applied the Calcosoft system with CAFE (Cellular Automaton Finite Element module. This module which belongs to „multiphysics” models enables structure prediction of complete casting with division of columnar and equiaxed crystals zones of -phase. Sensitivity tests of coupled model on the particular values parameters changing were made. On these basis it was determined the relations of CET (columnar-to-equaiaxed transition zone position influence. The example of virtual structure validation based on real structure with CET zone location and grain size was shown.
Sustainable Management of Coastal Environments Through Coupled Terrestrial-Coastal Ocean Models
Lohrenz, S. E.; Cai, W.; Tian, H.; He, R.; Xue, Z.; Fennel, K.; Hopkinson, C.; Howden, S. D.
2012-12-01
Changing climate and land use practices have the potential to dramatically alter coupled hydrologic-biogeochemical processes and associated movement of water, carbon and nutrients through various terrestrial reservoirs into rivers, estuaries, and coastal ocean waters. Consequences of climate- and land use-related changes will be particularly evident in large river basins and their associated coastal outflow regions. The large spatial extent of such systems necessitates a combination of satellite observations and model-based approaches coupled with targeted ground-based site studies to adequately characterize relationships among climate forcing (e.g., wind, precipitation, temperature, solar radiation, humidity, extreme weather), land use practice/land cover change, and transport of materials through watersheds and, ultimately, to coastal regions. Here, we describe a NASA Interdisciplinary Science project that employs an integrated suite of models in conjunction with remotely sensed as well as targeted in situ observations with the objectives of describing processes controlling fluxes on land and their coupling to riverine, estuarine and ocean ecosystems. The objectives of this effort are to 1) assemble and evaluate long term datasets for the assessment of impacts of climate variability, extreme weather events, and land use practices on transport of water, carbon and nitrogen within terrestrial systems and the delivery of materials to waterways and rivers; 2) using the Mississippi River as a testbed, develop and evaluate an integrated suite of models to describe linkages between terrestrial and riverine systems, transport of carbon and nutrients in the Mississippi river and its tributaries, and associated cycling of carbon and nutrients in coastal ocean waters; and 3) evaluate uncertainty in model products and parameters and identify areas where improved model performance is needed through model refinement and data assimilation. The effort employs the Dynamic Land
Modeling Coupled THMC Processes and Brine Migration in Salt at High Temperatures
Energy Technology Data Exchange (ETDEWEB)
Rutqvist, Jonny; Blanco Martin, Laura; Mukhopadhyay, Sumit; Houseworth, Jim; Birkholzer, Jens
2014-08-14
In this report, we present FY2014 progress by Lawrence Berkeley National Laboratory (LBNL) related to modeling of coupled thermal-hydrological-mechanical-chemical (THMC) processes in salt and their effect on brine migration at high temperatures. LBNL’s work on the modeling of coupled THMC processes in salt was initiated in FY2012, focusing on exploring and demonstrating the capabilities of an existing LBNL modeling tool (TOUGH-FLAC) for simulating temperature-driven coupled flow and geomechanical processes in salt. This work includes development related to, and implementation of, essential capabilities, as well as testing the model against relevant information and published experimental data related to the fate and transport of water. we provide more details on the FY2014 work, first presenting updated tools and improvements made to the TOUGH-FLAC simulator, and the use of this updated tool in a new model simulation of long-term THM behavior within a generic repository in a salt formation. This is followed by the description of current benchmarking and validations efforts, including the TSDE experiment. We then present the current status in the development of constitutive relationships and the dual-continuum model for brine migration. We conclude with an outlook for FY2015, which will be much focused on model validation against field experiments and on the use of the model for the design studies related to a proposed heater experiment.
Arndt, Sandra
2016-04-01
Marine sediments are key components in the Earth System. They host the largest carbon reservoir on Earth, provide the only long term sink for atmospheric CO2, recycle nutrients and represent the most important climate archive. Biogeochemical processes in marine sediments are thus essential for our understanding of the global biogeochemical cycles and climate. They are first and foremost, donor controlled and, thus, driven by the rain of particulate material from the euphotic zone and influenced by the overlying bottom water. Geochemical species may undergo several recycling loops (e.g. authigenic mineral precipitation/dissolution) before they are either buried or diffuse back to the water column. The tightly coupled and complex pelagic and benthic process interplay thus delays recycling flux, significantly modifies the depositional signal and controls the long-term removal of carbon from the ocean-atmosphere system. Despite the importance of this mutual interaction, coupled regional/global biogeochemical models and (paleo)climate models, which are designed to assess and quantify the transformations and fluxes of carbon and nutrients and evaluate their response to past and future perturbations of the climate system either completely neglect marine sediments or incorporate a highly simplified representation of benthic processes. On the other end of the spectrum, coupled, multi-component state-of-the-art early diagenetic models have been successfully developed and applied over the past decades to reproduce observations and quantify sediment-water exchange fluxes, but cannot easily be coupled to pelagic models. The primary constraint here is the high computation cost of simulating all of the essential redox and equilibrium reactions within marine sediments that control carbon burial and benthic recycling fluxes: a barrier that is easily exacerbated if a variety of benthic environments are to be spatially resolved. This presentation provides an integrative overview of
Ingwersen, Joachim; Högy, Petra; Wizemann, Hans-Dieter; Streck, Thilo
2017-04-01
Weather and climate simulations depend on an accurate description of the exchange of water, energy and momentum between land surface and atmosphere. In state-of-the-art land surface models the vegetation dynamics is "frozen" that means prescribed in lookup tables. As a consequence growth and development of a crop is independent from the prevailing weather conditions, and an important feedback between atmosphere and land surface is not captured. In the present study we coupled the land surface model NOAHMP with the mechanistic generic crop growth model GECROS. On the basis of a comprehensive 5-year dataset on eddy covariance energy- and water fluxes and soil water and crop data from two different climate regions of Southwest Germany, we adapted the crop growth model GECROS, integrated it with NOAHMP, calibrated the coupled model for winter wheat and silage maize and tested its robustness in multiple-year validation runs against independent measurements. For winter wheat the model performed well both for the calibration and validation phase. Inter-annual and regional differences in crop development due to temperature anomalies were well reproduced by the model. Also the decline of evapotranspiration over the maturing phase was properly simulated. In case of maize the model performed not as good as for winter wheat. We attribute this somewhat lower model performance to the pronounced differences among maize cultivars, the high sensitivity of maize development to drill and emergence date, and its higher susceptibility to early summer droughts. Moreover, the model systematically overestimated evapotranspiration during long lasting droughts like in June 2014 indicating that in the current state NOAHMP-GECROS has some limitations in simulating water stress. We attribute this weakness to the uniform root distribution and the hydraulic functions (Clapp-Hornberger) that are implemented in NOAHMP which result in a uniform depletion of the soil water profile. The novel model
Development of a 1D canopy module to couple mesoscale meteorogical model with building energy model
Mauree, Dasaraden; Kohler, Manon; Blond, Nadège; Clappier, Alain
2013-04-01
computational time. To simulate the processes at the micro-scale (building) as well as at the meso-scale (city and surroundings), it is necessary to connect these two types of models. It is proposed here to develop a canopy module able to act as an interface between these two scales. The meso-scale model provides the meteorological parameters to the micro-scale model via the canopy module. The micro-scale model then calculates the influence of the different type of surfaces on the variables and gives its back through the module to the meso-scale model. By simulating in a better way the interactions between the atmosphere and the urban surfaces, the model will enhance the estimation of the energy use by building. The tool produced by this research could be coupled in the future with an urban dynamics model to optimize urban planning in order to improve the sustainability of cities.
Warner, J. C.; Armstrong, B. N.; He, R.; Zambon, J. B.; Olabarrieta, M.; Voulgaris, G.; Kumar, N.; Haas, K. A.
2012-12-01
Understanding processes responsible for coastal change is important for managing both our natural and economic coastal resources. Coastal processes respond from both local scale and larger regional scale forcings. Understanding these processes can lead to significant insight into how the coastal zone evolves. Storms are one of the primary driving forces causing coastal change from a coupling of wave and wind driven flows. Here we utilize a numerical modeling approach to investigate these dynamics of coastal storm impacts. We use the Coupled Ocean - Atmosphere - Wave - Sediment Transport (COAWST) Modeling System that utilizes the Model Coupling Toolkit to exchange prognostic variables between the ocean model ROMS, atmosphere model WRF, wave model SWAN, and the Community Sediment Transport Modeling System (CSTMS) sediment routines. The models exchange fields of sea-surface temperature, ocean currents, water levels, bathymetry, wave heights, lengths, periods, bottom orbital velocities, and atmospheric surface heat and momentum fluxes, atmospheric pressure, precipitation, and evaporation. Data fields are exchanged using regridded flux conservative sparse matrix interpolation weights computed from the SCRIP spherical coordinate remapping interpolation package. We describe the modeling components and the model field exchange methods. As part of the system, the wave and ocean models run with cascading, refined, spatial grids to provide increased resolution, scaling down to resolve nearshore wave driven flows simulated by the vortex force formulation, all within selected regions of a larger, coarser-scale coastal modeling system. The ocean and wave models are driven by the atmospheric component, which is affected by wave dependent ocean-surface roughness and sea surface temperature which modify the heat and momentum fluxes at the ocean-atmosphere interface. We describe the application of the modeling system to several regions of multi-scale complexity to identify the
Analyzing Sexual Health-Related Beliefs Among Couples in Marriage Based on the Health Belief Model
Directory of Open Access Journals (Sweden)
Majid Barati
2014-06-01
Full Text Available Introduction: Sexual health is the integrity between mind, emotions, and body, and any disorder leading to discoordination, can be associated with sexual dysfunction. The aim of this study was to investigate the beliefs of couples attending marriage counseling centers toward sexual health based on the health belief model. Materials and Methods: This cross sectional descriptive study was performed on 400 couples referring to marriage counseling centers of Hamadan recruited with a random sampling method. The participants completed a self-administered questionnaire including demographic characteristics, knowledge and health belief model constructs. Data analysis was performed using SPSS-16 software, by Pearson’s coefficient correlation, independent T-test, and one-way ANOVA. Results: Couples had a moderate knowledge of sexual health. In addition, perceived susceptibility and severity of the consequences of unsafe sexual behavior among couples were not satisfactory however, perceived benefits and barriers were reported in a relatively good level. Internet and friends were the most important sources for sexual health information. Conclusion: Promoting knowledge and beliefs toward sexual health by preparing training packages based on the needs of couples and removing obstacles to have normal sexual behavior are necessary.
Energy Technology Data Exchange (ETDEWEB)
Wahlen-Strothman, J. M. [Rice Univ., Houston, TX (United States); Henderson, T. H. [Rice Univ., Houston, TX (United States); Hermes, M. R. [Rice Univ., Houston, TX (United States); Degroote, M. [Rice Univ., Houston, TX (United States); Qiu, Y. [Rice Univ., Houston, TX (United States); Zhao, J. [Rice Univ., Houston, TX (United States); Dukelsky, J. [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Inst. de Estructura de la Materia; Scuseria, G. E. [Rice Univ., Houston, TX (United States)
2018-01-03
Coupled cluster and symmetry projected Hartree-Fock are two central paradigms in electronic structure theory. However, they are very different. Single reference coupled cluster is highly successful for treating weakly correlated systems, but fails under strong correlation unless one sacrifices good quantum numbers and works with broken-symmetry wave functions, which is unphysical for finite systems. Symmetry projection is effective for the treatment of strong correlation at the mean-field level through multireference non-orthogonal configuration interaction wavefunctions, but unlike coupled cluster, it is neither size extensive nor ideal for treating dynamic correlation. We here examine different scenarios for merging these two dissimilar theories. We carry out this exercise over the integrable Lipkin model Hamiltonian, which despite its simplicity, encompasses non-trivial physics for degenerate systems and can be solved via diagonalization for a very large number of particles. We show how symmetry projection and coupled cluster doubles individually fail in different correlation limits, whereas models that merge these two theories are highly successful over the entire phase diagram. Despite the simplicity of the Lipkin Hamiltonian, the lessons learned in this work will be useful for building an ab initio symmetry projected coupled cluster theory that we expect to be accurate in the weakly and strongly correlated limits, as well as the recoupling regime.
Wahlen-Strothman, Jacob M; Henderson, Thomas M; Hermes, Matthew R; Degroote, Matthias; Qiu, Yiheng; Zhao, Jinmo; Dukelsky, Jorge; Scuseria, Gustavo E
2017-02-07
Coupled cluster and symmetry projected Hartree-Fock are two central paradigms in electronic structure theory. However, they are very different. Single reference coupled cluster is highly successful for treating weakly correlated systems but fails under strong correlation unless one sacrifices good quantum numbers and works with broken-symmetry wave functions, which is unphysical for finite systems. Symmetry projection is effective for the treatment of strong correlation at the mean-field level through multireference non-orthogonal configuration interaction wavefunctions, but unlike coupled cluster, it is neither size extensive nor ideal for treating dynamic correlation. We here examine different scenarios for merging these two dissimilar theories. We carry out this exercise over the integrable Lipkin model Hamiltonian, which despite its simplicity, encompasses non-trivial physics for degenerate systems and can be solved via diagonalization for a very large number of particles. We show how symmetry projection and coupled cluster doubles individually fail in different correlation limits, whereas models that merge these two theories are highly successful over the entire phase diagram. Despite the simplicity of the Lipkin Hamiltonian, the lessons learned in this work will be useful for building an ab initio symmetry projected coupled cluster theory that we expect to be accurate in the weakly and strongly correlated limits, as well as the recoupling regime.
Couple Infertility: From the Perspective of the Close-Relationship Model.
Higgins, Barbara S.
1990-01-01
Presents Close-Relationship Model as comprehensive framework in which to examine interrelated nature of causes and effects of infertility on marital relationship. Includes these factors: physical and psychological characteristics of both partners; joint, couple characteristics; physical and social environment; and relationship itself. Discusses…
DEFF Research Database (Denmark)
Wu, Kehuai; Madsen, Jan
2007-01-01
and resource management, and iii) present a SystemC based framework to model and simulate coprocessor-coupled reconfigurable systems. We illustrate how COSMOS may be used to capture the dynamic behavior of such systems and emphasize the need for capturing the system aspects of such systems in order to deal...
Lucarini, Valerio; Vannitsem, Stephane
2016-04-01
We study a simplified coupled atmosphere-ocean model using the formalism of covariant Lyapunov vectors (CLVs), which link physically-based directions of perturbations to growth/decay rates. The model is obtained via a severe truncation of quasi-geostrophic equations for the two fluids, and includes a simple yet physically meaningful representation of their dynamical/thermodynamical coupling. The model has 36 degrees of freedom, and the parameters are chosen so that a chaotic behaviour is observed. One finds two positive Lyapunov exponents (LEs), sixteen negative LEs, and eighteen near-zero LEs. The presence of many near-zero LEs results from the vast time-scale separation between the characteristic time scales of the two fluids, and leads to nontrivial error growth properties in the tangent space spanned by the corresponding CLVs, which are geometrically very degenerate. Such CLVs correspond to two different classes of ocean/atmosphere coupled modes. The tangent space spanned by the CLVs corresponding to the positive and negative LEs has, instead, a non-pathological behaviour, and one can construct robust large deviations laws for the finite time LEs, thus providing a universal model for assessing predictability on long to ultra-long scales along such directions. Finally, it is somewhat surprising to find that the tangent space of the unstable manifold has strong projection on both atmospheric and oceanic components, thus giving evidence that coupled modes are responsible for the instability of the flow.
Wassing, B.B.T.; Wees, J.D. van; Fokker, P.A.
2012-01-01
We developed a coupled code to obtain a better understanding of the role of pore pressure changes in causing fracture reactivation and seismicity during EGS. We implemented constitutive models for fractures in a continuum approach, which is advantageous because of the ease of integration in existing
Inelastic scattering in a local polaron model with quadratic coupling to bosons
DEFF Research Database (Denmark)
Olsen, Thomas
2009-01-01
We calculate the inelastic scattering probabilities in the wide band limit of a local polaron model with quadratic coupling to bosons. The central object is a two-particle Green's function which is calculated exactly using a purely algebraic approach. Compared with the usual linear interaction term...
Chemical modeling of a high-density inductively-coupled plasma reactor containing silane
Kovalgin, Alexeij Y.; Boogaard, A.; Brunets, I.; Holleman, J.; Schmitz, Jurriaan
We carried out the modeling of chemical reactions in a silane-containing remote Inductively Coupled Plasma Enhanced Chemical Vapor Deposition (ICPECVD) system, intended for deposition of silicon, silicon oxide, and silicon nitride layers. The required electron densities and Electron Energy
Superconductivity in Hubbard models coupled to non-fermionic degrees of freedom
Raedt, H. De; Schneider, T.; Sörensen, M.P.
1990-01-01
We explore the consequences of coupling between repulsive Hubbard models and Bosonic or spin degrees of freedom. In the regime where the characteristic energy of the non-Fermionic part is large compared to the characteristic energy of the Fermions, the effective Hamiltonian corresponds to a
The role of the southern annular mode in dynamical global coupled model
CSIR Research Space (South Africa)
Beraki, AF
2013-09-01
Full Text Available The interannual and decadal variability of the Southern Annual Mode (SAM) was examined in the ECHAM 4.5-MOM3-SA ocean-atmosphere coupled general circulation model (OAGCM). The analysis placed emphasis on the behavior of the SAM when its variability...
Control of a coupled map lattice model for vortex shedding in the ...
Indian Academy of Sciences (India)
vortex shedding, can be sensed in an experiment through standard hot-film velocity mea- surement .... In this section, we discuss certain features in the development of three coupled map lattice models where ..... vortex shedding behind circular cylinders, in ASME forum on unsteady flow separation, FED. 52, 1 (1987).
Grobbe, N.
2016-01-01
In this thesis, I study coupled poroelastic waves and electromagnetic fields in layered media. The focus is two-fold:
1. Increase the theoretical and physical understanding of the seismo-electromagnetic phenomenon by analytically-based numerical modeling.
2. Investigate the potential of
Surface-wave mode coupling : modelling and inverting waveforms including body-wave phases
Marquering, H.A.
1996-01-01
This thesis is concerned with a similar problem as addressed by Li & Tanimoto (1993) in the surfacewave mode approach. In this thesis it is shown that surface-wave mode coupling is required when body-wave phases in laterally heterogeneous media are modelled by surface-wave mode summation. An
A coupled physical-biological-chemical model for the Indian Ocean
Indian Academy of Sciences (India)
The coupled model reproduces the high productivity observed in the Arabian Sea off the Somali and Omani coasts during the Southwest (SW) monsoon. The entire Arabian Sea is an outgassing region for CO2 in spite of high productivity with transfer rates as high as 80 m-mol C/m2/day during SW monsoon near the Somali ...
Simulation of snowstorm over the Yellow Sea using a mesoscale coupled model
Heo, Ki-Young; Kim, Kyung-Eak; Ha, Kyung-Ja; Park, Kwang-Soon; Jun, Ki-Cheon; Shim, Jae-Seol; Suh, Young-Sang
2010-11-01
This study aims to examine the favorable conditions for an ocean effect snowstorm across the Yellow Sea over the southwestern coast of Korea on 21 December 2005, using a coupled model with a Coupled Ocean/Atmosphere Mesoscale Prediction System as the atmospheric component and the Regional Ocean Modeling System as the oceanic component. Simulation of heavy snowfall event, which was 44.3 cm of snow accumulated in 24-hour, was performed to investigate the mesoscale structure, dynamics and development mechanisms in the snowstorm. As a result from 48-hour integration, the results of simulation showed that barotropic instability and turbulent heat fluxes played important roles in the formation of snowstorm. The enhanced surface diabatic heating was dominant in the latent heat flux, and eventually induced convective instability. An additional factor was the favorable condition of synoptic environment, accessing the cold air transport by the approach of the upper-level cold vortex over the warm ocean. Besides these factors, conditional symmetric instability (CSI) is a mechanism which can result in a heavy snowfall with sufficient moisture and upward vertical motion. A slantwise convection from the release of CSI could support a complex snowfall event with heavier than expected amounts. The result comparison between a coupled model and an uncoupled model supports that airsea coupling has an impact of decreasing of about 10% in a snowfall amount on the snowstorm.
Integrating social science into empirical models of coupled human and natural systems
Jeffrey D. Kline; Eric M. White; A Paige Fischer; Michelle M. Steen-Adams; Susan Charnley; Christine S. Olsen; Thomas A. Spies; John D. Bailey
2017-01-01
Coupled human and natural systems (CHANS) research highlights reciprocal interactions (or feedbacks) between biophysical and socioeconomic variables to explain system dynamics and resilience. Empirical models often are used to test hypotheses and apply theory that represent human behavior. Parameterizing reciprocal interactions presents two challenges for social...
3D modelling of coupled mass and heat transfer of a convection-oven roasting process
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu; Adler-Nissen, Jens; Gernaey, Krist
2013-01-01
are based on a conservation of mass and energy, coupled through Darcy's equations of porous media - the water flow is mainly pressure-driven. The developed model together with theoretical and experimental assessments were used to explain the heat and water transport and the effect of the change...
Coupling advection and chemical kinetics in a global atmospheric test model
E.J. Spee (Edwin)
1995-01-01
textabstractIn this paper we consider the numerical difficulties that arise when horizontal advection is coupled with chemistry on a sphere, using operator splitting. From a numerical point of view, these two processes are the most difficult parts of an atmospheric model for global studies. The
ASPECTS OF DESIGN PROCESS AND CAD MODELLING OF AN ADJUSTABLE CENTRIFUGAL COUPLING
Directory of Open Access Journals (Sweden)
Adrian BUDALĂ
2015-05-01
Full Text Available The paper deals with constructive and functional elements of an adjustable coupling with friction shoes and adjustable driving. Also, the paper shows few stages of the design process, some advantages of the using CAD software and some comparative results prototype vs. CAD model.
A Coupled fcGCM-GCE Modeling System: A 3D Cloud Resolving Model and a Regional Scale Model
Tao, Wei-Kuo
2005-01-01
Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and ore sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1998 and 1999). Also, at Goddard, we have implemented several Goddard microphysical schemes (21CE, several 31CE), Goddard radiation (including explicity calculated cloud optical properties), and Goddard Land Information (LIS, that includes the CLM and NOAH land surface models) into a next generation regional scale model, WRF. In this talk, I will present: (1) A Brief review on GCE model and its applications on precipitation processes (microphysical and land processes), (2) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), and preliminary results (the comparison with traditional GCMs), (3) A discussion on the Goddard WRF version (its developments and applications), and (4) The characteristics of the four-dimensional cloud data
Modelling of PCB trophic transfer in the Gulf of Lions; 3D coupled model application
Alekseenko, Elena; Thouvenin, Benedicte; Tronczynsky, Jacek; Carlotti, Francois; Garreau, Pierre; Tixier, Celine; Baklouti, Melika
2017-04-01
This work aims at assessing the role of plankton in the transfer of PCBs to higher trophic levels in the Gulf of Lions (NW Mediterranean Sea) using a 3D modelling approach, which is coupling biogeochemical and hydrodynamical processes and taking into account the physical-chemical properties of PCBs. Transport of various PCB species were simulated during one year: total dissolved, freely dissolved, particulate, biosorbed on plankton, assimilated by zooplankton. PCB budgets and fluxes into the Gulf of Lions between various species were governed by different processes, such as: adsorption/desorption, bacteria and plankton mortality, zooplankton excretion, grazing, mineralization, volatilization and biodegradation. CB153 (2,2',4,4',5,5' hexachlorobiphényle) congener have been considered in the model, since it presents a large amount of PCB among the other congeners in the environment of the Gulf of Lions. At first, the simulated PCBs distributions within particulate matter and plankton were compared with available in-situ measurements (COSTAS and Merlumed field campaigns) performed in the Gulf of Lions. Two size classes of plankton X (60μ mwater to plankton. For all zones CB153 concentration is raising in January and in July 2010, what is linked with two Rhone River flood events started in the middle of December 2009 and in the middle of June 2010. In all zones among the organisms bacteria adsorbs more and copepod adsorbs less CB153, such a tendency increases from shallower to deeper zone. In the offshore zone HNF obtain more CB153 from bacteria through grazing than other predators. In turn, in the intermediate zone copepod's grazed CB153 is more dominant.
The Situated HKB Model: how sensorimotor spatial coupling can alter oscillatory brain dynamics
Directory of Open Access Journals (Sweden)
Miguel eAguilera
2013-08-01
Full Text Available Despite the increase both of dynamic and embodied/situated approaches in cognitive science, there is still little research on how coordination dynamics under a closed sensorimotor loop might induce qualitatively different patterns of neural oscillations compared to those found in isolated systems. We take as a departure point the HKB model, a generic model for dynamic coordination between two oscillatory components, which has proven useful for a vast range of applications in cognitive science and whose dynamical properties are well understood. In order to explore the properties of this model under closed sensorimotor conditions we present what we call the situated HKB model: a robotic model that performs a gradient climbing task and whose "brain" is modelled by the HKB equation. We solve the differential equations that define the agent-environment coupling for increasing values of the agent's sensitivity (sensor gain, finding different behavioural strategies. These results are compared with two different models: a decoupled HKB with no sensory input and a passively-coupled HKB that is also decoupled but receives a structured input generated by a situated agent. We can precisely quantify and qualitatively describe how the properties of the system, when studied in coupled conditions, radically change in a manner that cannot be deduced from the decoupled HKB models alone. We also present the notion of neurodynamic signature as the dynamic pattern that correlates with a specific behaviour and we show how only a situated agent can display this signature compared to an agent that simply receives the exact same sensory input.To our knowledge, this is the first analytical solution of the HKB equation in a sensorimotor loop and qualitative and quantitative analytic comparison of spatially coupled vs. decoupled oscillatory controllers. Finally, we discuss the limitations and possible generalization of our model to contemporary neuroscience and philosophy
The situated HKB model: how sensorimotor spatial coupling can alter oscillatory brain dynamics
Aguilera, Miguel; Bedia, Manuel G.; Santos, Bruno A.; Barandiaran, Xabier E.
2013-01-01
Despite the increase of both dynamic and embodied/situated approaches in cognitive science, there is still little research on how coordination dynamics under a closed sensorimotor loop might induce qualitatively different patterns of neural oscillations compared to those found in isolated systems. We take as a departure point the Haken-Kelso-Bunz (HKB) model, a generic model for dynamic coordination between two oscillatory components, which has proven useful for a vast range of applications in cognitive science and whose dynamical properties are well understood. In order to explore the properties of this model under closed sensorimotor conditions we present what we call the situated HKB model: a robotic model that performs a gradient climbing task and whose “brain” is modeled by the HKB equation. We solve the differential equations that define the agent-environment coupling for increasing values of the agent's sensitivity (sensor gain), finding different behavioral strategies. These results are compared with two different models: a decoupled HKB with no sensory input and a passively-coupled HKB that is also decoupled but receives a structured input generated by a situated agent. We can precisely quantify and qualitatively describe how the properties of the system, when studied in coupled conditions, radically change in a manner that cannot be deduced from the decoupled HKB models alone. We also present the notion of neurodynamic signature as the dynamic pattern that correlates with a specific behavior and we show how only a situated agent can display this signature compared to an agent that simply receives the exact same sensory input. To our knowledge, this is the first analytical solution of the HKB equation in a sensorimotor loop and qualitative and quantitative analytic comparison of spatially coupled vs. decoupled oscillatory controllers. Finally, we discuss the limitations and possible generalization of our model to contemporary neuroscience and
Chua, V. P.
2015-12-01
Intensive agricultural, economic and industrial activities in Singapore and Malaysia have made our coastal areas under high risk of water pollution. A coupled ocean-hydrologic model is employed to perform three-dimensional simulations of flow and pollutant transport in Singapore coastal waters. The hydrologic SWAT model is coupled with the coastal ocean SUNTANS model by outputting streamflow and pollutant concentrations from the SWAT model and using them as inputs for the SUNTANS model at common boundary points. The coupled model is calibrated with observed sea surface elevations and velocities, and high correlation coefficients that exceed 0.97 and 0.91 are found for sea surface elevations and velocities, respectively. The pollutants are modeled as Gaussian passive tracers, and are released at five upstream locations in Singapore coastal waters. During the Northeast monsoon, pollutants released in Source 1 (Johor River), Source 2 (Tiram River), Source 3 (Layang River) and Source 4 (Layau River) enter the Singapore Strait after 4 days of release and reach Sentosa Island within 9 days. Meanwhile, pollutants released in Source 5 (Kallang River) reach Sentosa Island after 4 days. During the Southwest monsoon, the dispersion time is roughly doubled, with pollutants from Sources 1 - 4 entering the Singapore Strait only after 12 days of release due to weak currents.
Mayo, A. W.; Mutamba, J.
A coupled model was developed that incorporates all the major nitrogen transformation mechanisms influencing nitrogen removal in aquatic systems. The model simulates nitrogen transformation and removal processes in the high rate pond (HRP) and the subsurface constructed wetland unit (SSCW). The model considered organic nitrogen (ON), ammonia nitrogen (NH 3-N), and nitrate nitrogen ( NO3--N) as the major forms of nitrogen involved in the transformation chains. The influencing transformation mechanisms considered in the model include uptake of inorganic nitrogen by algae and bacteria, mineralization, sedimentation, volatilisation of ammonia and nitrification coupled with denitrification processes. The results showed that improved nitrogen removal occurred with increase in hydraulic time of the HRP unit. It was also revealed that the HRP can effectively be used to promote nitrification and subsurface flow gravel bed constructed wetland can be used as a denitrifying unit. The most efficient mechanisms were determined using a transformation model. The model indicated that nitrification and mineralization were dominant contributing 51.1% and 14.9%, respectively. Denitrification and mineralization were most significant in the SSCW accounting for 43.5% and 16.7%, respectively. Nitrification-denitrification route was observed to be the most significant mechanism for nitrogen removal in the coupled system with an overall contribution of 53%. The model predicted the overall nitrogen removal as 37% compared to 38.4% obtained from field measurements.
A Coupled Phase-Temperature Model for Dynamics of Transient Neuronal Signal in Mammals Cold Receptor
Directory of Open Access Journals (Sweden)
Firman Ahmad Kirana
2016-01-01
Full Text Available We propose a theoretical model consisting of coupled differential equation of membrane potential phase and temperature for describing the neuronal signal in mammals cold receptor. Based on the results from previous work by Roper et al., we modified a nonstochastic phase model for cold receptor neuronal signaling dynamics in mammals. We introduce a new set of temperature adjusted functional parameters which allow saturation characteristic at high and low steady temperatures. The modified model also accommodates the transient neuronal signaling process from high to low temperature by introducing a nonlinear differential equation for the “effective temperature” changes which is coupled to the phase differential equation. This simple model can be considered as a candidate for describing qualitatively the physical mechanism of the corresponding transient process.
Recent progress and review of Physics Dynamics Coupling in geophysical models
Gross, Markus; Rasch, Philip J; Caldwell, Peter M; Williamson, David L; Klocke, Daniel; Jablonowski, Christiane; Thatcher, Diana R; Wood, Nigel; Cullen, Mike; Beare, Bob; Willett, Martin; Lemarié, Florian; Blayo, Eric; Malardel, Sylvie; Termonia, Piet; Gassmann, Almut; Lauritzen, Peter H; Johansen, Hans; Zarzycki, Colin M; Sakaguchi, Koichi; Leung, Ruby
2016-01-01
Geophysical models of the atmosphere and ocean invariably involve parameterizations. These represent two distinct areas: a) Subgrid processes which the model cannot (yet) resolve, due to its discrete resolution, and b) sources in the equation, due to radiation for example. Hence coupling between these physics parameterizations and the resolved fluid dynamics and also between the dynamics of the different fluids in the system (air and water) is necessary. This coupling is an important aspect of geophysical models. However, often model development is strictly segregated into either physics or dynamics. Hence, this area has many more unanswered questions than in-depth understanding. Furthermore, recent developments in the design of dynamical cores (e.g. significant increase of resolution, move to non-hydrostatic equation sets etc), extended process physics (e.g. prognostic micro physics, 3D turbulence, non-vertical radiation etc) and predicted future changes of the computational infrastructure (e.g. Exascale wit...
Current induced torques and interfacial spin-orbit coupling: Semiclassical modeling
Haney, Paul M.
2013-05-07
In bilayer nanowires consisting of a ferromagnetic layer and a nonmagnetic layer with strong spin-orbit coupling, currents create torques on the magnetization beyond those found in simple ferromagnetic nanowires. The resulting magnetic dynamics appear to require torques that can be separated into two terms, dampinglike and fieldlike. The dampinglike torque is typically derived from models describing the bulk spin Hall effect and the spin transfer torque, and the fieldlike torque is typically derived from a Rashba model describing interfacial spin-orbit coupling. We derive a model based on the Boltzmann equation that unifies these approaches. We also consider an approximation to the Boltzmann equation, the drift-diffusion model, that qualitatively reproduces the behavior, but quantitatively differs in some regimes. We show that the Boltzmann equation with physically reasonable parameters can match the torques for any particular sample, but in some cases, it fails to describe the experimentally observed thickness dependencies.
Coupling lattice Boltzmann model for simulation of thermal flows on standard lattices
Li, Q; He, Y L; Gao, Y J; Tao, W Q
2011-01-01
In this paper, a coupling lattice Boltzmann (LB) model for simulating thermal flows on the standard D2Q9 lattice is developed in the framework of the double-distribution-function (DDF) approach in which the viscous heat dissipation and compression work are considered. In the model, a density distribution function is used to simulate the flow field, while a total energy distribution function is employed to simulate the temperature field. The discrete equilibrium density and total energy distribution functions are obtained from the Hermite expansions of the corresponding continuous equilibrium distribution functions. The pressure given by the equation of state of perfect gases is recovered in the macroscopic momentum and energy equations. The coupling between the momentum and energy transports makes the model applicable for general thermal flows such as non-Boussinesq flows, while the existing DDF LB models on standard lattices are usually limited to Boussinesq flows in which the temperature variation is small....
Energy Technology Data Exchange (ETDEWEB)
Jonkman, J. M.; Sclavounos, P. D.
2006-01-01
Aeroelastic simulation tools are routinely used to design and analyze onshore wind turbines, in order to obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These tools employ sophisticated models of wind-inflow; aerodynamic, gravitational, and inertial loading of the rotor, nacelle, and tower; elastic effects within and between components; and mechanical actuation and electrical responses of the generator and of control and protection systems. For offshore wind turbines, additional models of the hydrodynamic loading in regular and irregular seas, the dynamic coupling between the support platform motions and wind turbine motions, and the dynamic characterization of mooring systems for compliant floating platforms are also important. Hydrodynamic loading includes contributions from hydrostatics, wave radiation, and wave scattering, including free surface memory effects. The integration of all of these models into comprehensive simulation tools, capable of modeling the fully coupled aeroelastic and hydrodynamic responses of floating offshore wind turbines, is presented.
Directory of Open Access Journals (Sweden)
H. Shen
2015-05-01
Full Text Available Drought assessment is essential for coping with frequent droughts nowadays. Owing to the large spatio-temporal variations in hydrometeorology in most regions in China, it is very necessary to use a physically-based hydrological model to produce rational spatial and temporal distributions of hydro-meteorological variables for drought assessment. In this study, the large-scale distributed hydrological model Variable Infiltration Capacity (VIC was coupled with a modified standardized runoff index (SRI for drought assessment in the Weihe River basin, northwest China. The result indicates that the coupled model is capable of reasonably reproducing the spatial distribution of drought occurrence. It reflected the spatial heterogeneity of regional drought and improved the physical mechanism of SRI. This model also has potential for drought forecasting, early warning and mitigation, given that accurate meteorological forcing data are available.
A review of the coupling software developed and used in the climate modelling community
Valcke, S.
2009-04-01
Coupling numerical codes is certainly not a new preoccupation in the climate research community and in other research fields such as electromagnetism or computational fluid dynamics. Ideally, the software interface between the different scientific modules should ensure an efficient realization of the coupled simulation on different types of platforms while allowing testing of different coupling algorithms and an easy replacement of one or more modules for inter comparison exercises. These specifications suggest modularity, portability and efficiency as key concepts onto which to base the design of the software. In the climate modelling community, different approaches exist to answer these specifications. On one hand, some tools ensure a minimal level of interference in the original codes so that they will run in the coupled system with main characteristics unchanged with respect to the uncoupled mode. This approach, while in some cases less efficient than a more integrated approach, is probably the best trade-off that can be chosen when the different component models come from different research groups that also use these components independently in stand-alone mode for other research purposes and that are not likely to follow strict coding rules imposed by external constraints. On the other hand, some tools or frameworks require more modification or adaptation of the original codes and are used to build and control a hierarchical merged application integrating the different elemental pieces of the original codes. This approach ensures efficient coupling exchanges within the merged application but requires a deeper level of interference in the codes and imposes strict coding rules in order to take full advantage of the framework functionalities. This second approach is therefore probably the most recommended one in a controlled top-down development environment. In this talk, we will review the different coupling tools developed and used in the climate modelling
Modeling of surface acoustic wave strain sensors using coupling-of-modes analysis.
Mc Cormack, Brian; Geraghty, Dermot; O'Mahony, Margaret
2011-11-01
SAW devices may be configured as strain sensors, providing passive, wireless strain measurement in demanding conditions. A key consideration is the modeling of the sensors, enabling different device designs to be considered. This paper presents a simulation scheme using coupling-of-modes (COM) analysis which allows both the frequency response of a SAW strain sensor and its bias sensitivity to be evaluated. Example applications are presented to demonstrate the use of the model.
A different approach to coupling a reservoir simulator with a surface facilities model
Energy Technology Data Exchange (ETDEWEB)
Trick, M. D. [Neotechnology Consultants Ltd., (United States)
1998-12-31
A method for coupling FORGAS, a commercial multiphase gas deliverability forecasting program and the commercial black oil reservoir simulator ECLIPSE 100 through Open Eclipse, a network simulator that uses a Parallel Virtual Machine interface, is proposed. The proposed procedure is claimed to yield a significant reduction in computation time without loss in accuracy or function. Commercial availability is another advantage claimed for this integrated model. A variety of other integrated models previously described in the literature are also reviewed. 17 refs., 1 tab.
Dynamical Coupled-Channel Model of Meson Production Reactions in the Nucleon Resonance Region
Energy Technology Data Exchange (ETDEWEB)
T.-S. H. Lee; A. Matsuyama; T. Sato
2006-11-15
A dynamical coupled-channel model is presented for investigating the nucleon resonances (N*) in the meson production reactions induced by pions and photons. Our objective is to extract the N* parameters and to investigate the meson production reaction mechanisms for mapping out the quark-gluon substructure of N* from the data. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method.
Hopf bifurcation in love dynamical models with nonlinear couples and time delays
Energy Technology Data Exchange (ETDEWEB)
Liao Xiaofeng [School of Computer and Information, Chongqing Jiaotong University, Chonqing 400074 (China) and Department of Computer Science and Engineering, Chongqing University, Chongqing 400030 (China)]. E-mail: xflao@cqu.edu.cn; Ran Jiouhong [Hospital of Chongqing University, Chonqing University, Chongqing 400030 (China)
2007-02-15
A love dynamical models with nonlinear couples and two delays is considered. Local stability of this model is studied by analyzing the associated characteristic transcendental equation. We find that the Hopf bifurcation occurs when the sum of the two delays varies and passes a sequence of critical values. The stability and direction of the Hopf bifurcation are determined by applying the normal form theory and the center manifold theorem. Numerical example is given to illustrate our results.
A new coupled map car-following model considering drivers' steady desired speed
Zhou, Tong; Sun, Di-Hua; Li, Hua-Min; Liu, Wei-Ning
2014-05-01
Based on the pioneering work of Konishi et al., in consideration of the influence of drivers' steady desired speed effect on the traffic flow, we develop a new coupled map car-following model in the real world. By use of the control theory, the stability condition of our model is derived. The validity of the present theoretical scheme is verified via numerical simulation, confirming the correctness of our theoretical analysis.
Erosion dynamics modelling in a coupled catchment-fan system with constant external forcing
Pepin, E.; Carretier, Sébastien; Hérail, Gérard
2010-01-01
Recent alluvial fan models have suggested that deep alluvial fan entrenchment could occur without any change in sediment and water influx. Moreover, other studies have shown that the evolution of a fan could strongly depend on feedback between the fan and the mountain catchment. We evaluate if natural entrenchment still occurs in a coupled catchment-fan system, and we evaluate its possible impact on the evolution of mountain erosion. We use a landscape evolution model where the mountain corre...
Fersch, Benjamin; Senatore, Alfonso; Kunstmann, Harald
2017-04-01
Fully-coupled hydrometeorological modeling enables investigations about the complex and often non-linear exchange mechanisms among subsurface, land, and atmosphere with respect to water and energy fluxes. The consideration of lateral redistribution of surface and subsurface water in such modeling systems is a crucial enhancement, allowing for a better representation of surface spatial patterns and providing also channel discharge predictions. However, the evaluation of fully-coupled simulations is difficult since the amount of physical detail along with feedback mechanisms leads to high degrees of freedom. Therefore, comprehensive observation data is required to obtain meaningful model configurations. We present a case study for a medium-sized river catchment in southern Germany that includes the calibration of the stand-alone and the evaluation of the fully-coupled WRF-Hydro modeling system with a horizontal resolution of 1 x 1 km2, for the period June to August 2015. ECMWF ERA-Interim reanalysis is used for model driving. Land-surface processes are represented by the Noah-MP land surface model. Land-cover is described by the EU CORINE data set. Observations for model evaluation are obtained from the TERENO Pre-Alpine observatory (http://www.imk-ifu.kit.edu/tereno.php) and are complemented by further measurements from the ScaleX campaign (http://scalex.imk-ifu.kit.edu) such as atmospheric profiles obtained from radiometer sounding and airborne systems as well as soil moisture and -temperature networks. We show how well water budgets and heat-fluxes are being reproduced by the stand-alone WRF, the stand-alone WRF-Hydro and the fully-coupled WRF-Hydro model.
Coupling and noise induced spiking-bursting transition in a parabolic bursting model
Ji, Lin; Zhang, Jia; Lang, Xiufeng; Zhang, Xiuhui
2013-03-01
The transition from tonic spiking to bursting is an important dynamic process that carry physiologically relevant information. In this work, coupling and noise induced spiking-bursting transition is investigated in a parabolic bursting model with specific discussion on their cooperation effects. Fast/slow analysis shows that weak coupling may help to induce the bursting by changing the geometric property of the fast subsystem so that the original unstable periodical solution are stabilized. It turned out that noise can play the similar stabilization role and induce bursting at appropriate moderate intensity. However, their cooperation may either strengthen or weaken the overall effect depending on the choice of noise level.
Southern hemisphere climate variability as represented by an ocean-atmosphere coupled model
CSIR Research Space (South Africa)
Beraki, A
2012-09-01
Full Text Available , 1996: Relationship of air temperature in New Zealand to regional anomalies in sea-surface temperature and atmospheric circulation. Int. J. Climatol., 16, 405?425. Beraki, A., D. DeWitt, W.A. Landman and O. Cobus, 2011: Ocean-Atmosphere Coupled... variability as represented by an ocean-atmosphere coupled model Asmerom Beraki1,2, Willem A. Landman2,3 and David DeWitt4 1South African Weather Service Pretoria, South Africa, asmerom.beraki@weahtersa.co.za 2Departement of Geography...
Dynamics for a two-atom two-mode intensity-dependent Raman coupled model
Energy Technology Data Exchange (ETDEWEB)
Singh, S., E-mail: vasudha-rnc1@rediffmail.com, E-mail: sudhhasingh@gmail.com; Gilhare, K. [Ranchi University, Department of Physics (India)
2016-06-15
We study the quantum dynamics of a two-atom Raman coupled model interacting with a quantized bimodal field with intensity-dependent coupling terms in a lossless cavity. The unitary transformation method used to solve the time-dependent problem also gives the eigensolutions of the interaction Hamiltonian. We study the atomic-population dynamics and dynamics of the photon statistics in the two cavity modes, and present evidence of cooperative effects in the production of antibunching and anticorrelations between the modes. We also investigate the effect of detuning on the evolution of second-order correlation functions and observe that the oscillations become more rapid for large detuning.
Cluster dynamics modelling of materials: A new hybrid deterministic/stochastic coupling approach
Terrier, Pierre; Athènes, Manuel; Jourdan, Thomas; Adjanor, Gilles; Stoltz, Gabriel
2017-12-01
Deterministic simulations of the rate equations governing cluster dynamics in materials are limited by the number of equations to integrate. Stochastic simulations are limited by the high frequency of certain events. We propose a coupling method combining deterministic and stochastic approaches. It allows handling different time scale phenomena for cluster dynamics. This method, based on a splitting of the dynamics, is generic and we highlight two different hybrid deterministic/stochastic methods. These coupling schemes are highly parallelizable and specifically designed to treat large size cluster problems. The proof of concept is made on a simple model of vacancy clustering under thermal ageing.
Phase space analysis for a scalar-tensor model with kinetic and Gauss-Bonnet couplings
Granda, L N
2016-01-01
We study the phase space for an scalar-tensor string inspired model of dark energy with non minimal kinetic and Gauss Bonnet couplings. The form of the scalar potential and of the coupling terms is of the exponential type, which give rise to appealing cosmological solutions. The critical points describe a variety of cosmological scenarios that go from matter or radiation dominated universe to dark energy dominated universe. There were found trajectories in the phase space departing from unstable or saddle fixed points and arriving to the stable scalar field dominated point corresponding to late-time accelerated expansion.
Angular Structure of Jet Quenching Within a Hybrid Strong/Weak Coupling Model
Casalderrey-Solana, Jorge; Milhano, Guilherme; Pablos, Daniel; Rajagopal, Krishna
2017-01-01
Within the context of a hybrid strong/weak coupling model of jet quenching, we study the modification of the angular distribution of the energy within jets in heavy ion collisions, as partons within jet showers lose energy and get kicked as they traverse the strongly coupled plasma produced in the collision. To describe the dynamics transverse to the jet axis, we add the effects of transverse momentum broadening into our hybrid construction, introducing a parameter $K\\equiv \\hat q/T^3$ that governs its magnitude. We show that, because of the quenching of the energy of partons within a jet, even when $K\
Schnedermann, Christoph; Muders, Vera; Ehrenberg, David; Schlesinger, Ramona; Kukura, Philipp; Heberle, Joachim
2016-04-13
Channelrhodopsins are light-gated ion channels with extensive applications in optogenetics. Channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) exhibits a red-shifted absorption spectrum as compared to Channelrhodopsin-2, which is highly beneficial for optogenetic application. The primary event in the photocycle of CaChR1 involves an isomerization of the protein-bound retinal chromophore. Here, we apply highly time-resolved vibronic spectroscopy to reveal the electronic and structural dynamics associated with the first step of the photocycle of CaChR1. We observe vibrationally coherent formation of the P1 intermediate exhibiting a twisted 13-cis retinal with a 110 ± 7 fs time constant. Comparison with low-temperature resonance Raman spectroscopy of the corresponding trapped photoproduct demonstrates that this rapidly formed P1 intermediate is stable for several hundreds of nanoseconds.
Matthes, Heidrun; Rinke, Annette; Zhou, Xu; Dethloff, Klaus
2017-08-01
Permafrost is one of the most important components of Arctic land. Regional atmosphere-snow-permafrost interactions can be best studied with Regional Climate Models (RCMs) due to their higher horizontal resolution compared to global climate models. The development of Arctic RCMs with sophisticated land models is therefore very important. Comparing RCMs with different land surface model (LSM) components then allows the quantification of the uncertainties associated with the LSM. This study analyzes two simulations of coupled atmosphere-land RCMs over the Arctic, which differ only in their land component, while the atmospheric model component is the same. Specifically, we examine HIRHAM5-CLM4 (HIRHAM5 coupled with the sophisticated land model CLM4) and HIRHAM5 (HIRHAM5 coupled with the simpler land model of ECHAM5). We discuss the two models' abilities to represent observations on permafrost-like permafrost extent, active layer thickness (ALT), and soil temperature profiles, as well as on the representation of the Arctic atmosphere, based on simulations over 1979-2014. In comparison to HIRHAM5, HIRHAM5-CLM4 significantly reduces the simulated bias in ALT and winter soil temperatures. We find that the simulation of soil temperature and subsequently ALT is sensitive to soil thermal and hydraulic parameter representation in the models. The simulation of permafrost extent is sensitive to the initial soil temperature state in the models. Both HIRHAM5 and HIRHAM5-CLM4 do similarly well in modeling the Arctic 2 m air temperature and atmospheric circulation. Changing the land model impacts the 2 m air temperature significantly over land and the atmospheric circulation predominantly over the Arctic Ocean, associated with changes in baroclinic cyclones.
Middle and inner ear modelling: from microCT images to 3D reconstruction and coupling of models.
Tachos, N S; Sakellarios, A I; Rigas, G; Isailovic, V; Ni, G; Bohnke, F; Filipovic, N; Bibas, T; Fotiadis, D I
2016-08-01
We present finite element (FE) modeling approaches of ear mechanics including 3-dimensional (3D) reconstruction of the human middle and inner ear. Specifically, we demonstrate a semi-automatic methodology for the 3D reconstruction of the inner ear structures, a FE harmonic response model of the middle ear to predict the stapes footplate frequency response, a 2D FE slice model of the cochlea for the coupled response at the micromechanical level for either acoustic or electrical excitation and a coupled FE middle ear model with a simplified cochlea box model to simulate the basilar membrane velocity in response to acoustic excitation. The proposed methodologies are validated against experimental and literature data and the results are in good agreement.
Emergent behavior in a coupled economic and coastline model for beach nourishment
Directory of Open Access Journals (Sweden)
E. D. Lazarus
2011-12-01
Full Text Available Developed coastal areas often exhibit a strong systemic coupling between shoreline dynamics and economic dynamics. "Beach nourishment", a common erosion-control practice, involves mechanically depositing sediment from outside the local littoral system onto an actively eroding shoreline to alter shoreline morphology. Natural sediment-transport processes quickly rework the newly engineered beach, causing further changes to the shoreline that in turn affect subsequent beach-nourishment decisions. To the limited extent that this landscape/economic coupling has been considered, evidence suggests that towns tend to employ spatially myopic economic strategies under which individual towns make isolated decisions that do not account for their neighbors. What happens when an optimization strategy that explicitly ignores spatial interactions is incorporated into a physical model that is spatially dynamic? The long-term attractor that develops for the coupled system (the state and behavior to which the system evolves over time is unclear. We link an economic model, in which town-manager agents choose economically optimal beach-nourishment intervals according to past observations of their immediate shoreline, to a simplified coastal-dynamics model that includes alongshore sediment transport and background erosion (e.g. from sea-level rise. Simulations suggest that feedbacks between these human and natural coastal processes can generate emergent behaviors. When alongshore sediment transport and spatially myopic nourishment decisions are coupled, increases in the rate of sea-level rise can destabilize economically optimal nourishment practices into a regime characterized by the emergence of chaotic shoreline evolution.
Li, Shanshan; Zhang, Guoshan; Wang, Jiang; Chen, Yingyuan; Deng, Bin
2018-02-01
This paper proposes that modified two-compartment Pinsky-Rinzel (PR) neural model can be used to develop the simple form of central pattern generator (CPG). The CPG is called as 'half-central oscillator', which constructed by two inhibitory chemical coupled PR neurons with time delay. Some key properties of PR neural model related to CPG are studied and proved to meet the requirements of CPG. Using the simple CPG network, we first study the relationship between rhythmical output and key factors, including ambient noise, sensory feedback signals, morphological character of single neuron as well as the coupling delay time. We demonstrate that, appropriate intensity noise can enhance synchronization between two coupled neurons. Different output rhythm of CPG network can be entrained by sensory feedback signals. We also show that the morphology of single neuron has strong effect on the output rhythm. The phase synchronization indexes decrease with the increase of morphology parameter's difference. Through adjusting coupled delay time, we can get absolutely phase synchronization and antiphase state of CPG. Those results of simulation show the feasibility of PR neural model as a valid CPG as well as the emergent behaviors of the particularly CPG.
Improving LER Coupling and PEP-II Luminosity with Model-Independent Analysis
Energy Technology Data Exchange (ETDEWEB)
Kitch, Lacey; /MIT, LNS
2007-10-31
The PEP-II storage ring at SLAC houses electrons (in the High-Energy Ring, or HER) and positrons (in the Low-Energy Ring, or LER) for collision. The goal of this project was to improve the linear optics of the LER in order to decrease coupling, thereby decreasing emittance and increasing luminosity. To do this, we first took turn by turn BPM (Beam Position Monitor) data of a single positron bunch at two betatron resonance excitations, extracted orbits from this data using Model-Independent Analysis, and from these orbits formed a virtual model of the accelerator. We then took this virtual model and found an accelerator configuration which we predicted would, by creating vertical symmetric sextupole bumps and adjusting the strengths of several key quadrupole magnets, improve the coupling and decrease the emittance in the LER. We dialed this configuration into the LER and observed the coupling, emittance, and luminosity. Coupling immediately improved, as predicted, and the y emittance dropped by a dramatic 40%. After the HER was adjusted to match the LER at the Interaction Point (IP), we saw a 10% increase in luminosity, from 10.2 x 10{sup 33}cm{sup -2}sec{sup -1} to 11.2 x 10{sup 33}cm{sup -2}sec{sup -1}, and achieved a record peak specific luminosity.
Nielsen, Arthur C
2017-09-01
Couple therapy is a complex undertaking that proceeds best by integrating various schools of thought. Grounded in an in-depth review of the clinical and research literature, and drawing on the author's 40-plus years of experience, this paper presents a comprehensive, flexible, and user-friendly roadmap for conducting couple therapy. It begins by describing "Couple Therapy 1.0," the basic conjoint couple therapy format in which partners talk to each other with the help of the therapist. After noting the limitations of this model, the paper introduces upgrades derived from systemic, psychodynamic, and behavioral/educational approaches, and shows how to combine and sequence them. The most important upgrade is the early focus on the couple's negative interaction cycle, which causes them pain and impedes their ability to address it. Using a clinical case example, the paper shows how all three approaches can improve couple process as a prerequisite for better problem solving. Additional modules and sequencing choice points are also discussed, including discernment counseling and encouraging positive couple experiences. © 2017 Family Process Institute.
Directory of Open Access Journals (Sweden)
L. Cheng
1996-01-01
Full Text Available This article deals with the modeling of vibrating structures immersed in both light and heavy fluids, and possible applications to noise control problems and industrial vessels containing fluids. A theoretical approach, using artificial spring systems to characterize the mechanical coupling between substructures, is extended to include fluid loading. A structure consisting of a plate-ended cylindrical shell and its enclosed acoustic cavity is analyzed. After a brief description of the proposed technique, a number of numerical results are presented. The analysis addresses the following specific issues: the coupling between the plate and the shell; the coupling between the structure and the enclosure; the possibilities and difficulties regarding internal soundproofing through modifications of the joint connections; and the effects of fluid loading on the vibration of the structure.
The strong-weak coupling symmetry in 2D Φ4 field models
Directory of Open Access Journals (Sweden)
B.N.Shalaev
2005-01-01
Full Text Available It is found that the exact beta-function β(g of the continuous 2D gΦ4 model possesses two types of dual symmetries, these being the Kramers-Wannier (KW duality symmetry and the strong-weak (SW coupling symmetry f(g, or S-duality. All these transformations are explicitly constructed. The S-duality transformation f(g is shown to connect domains of weak and strong couplings, i.e. above and below g*. Basically it means that there is a tempting possibility to compute multiloop Feynman diagrams for the β-function using high-temperature lattice expansions. The regular scheme developed is found to be strongly unstable. Approximate values of the renormalized coupling constant g* found from duality symmetry equations are in an agreement with available numerical results.
Heresi Milad, Eliana; Rivera Ottenberger, Diana; Huepe Artigas, David
2014-01-01
This study aimed to explore the associations among attachment system type, sexual satisfaction, and marital satisfaction in adult couples in stable relationships. Participants were 294 couples between the ages of 20 and 70 years who answered self-administered questionnaires. Hierarchical linear modeling revealed that the anxiety and avoidance, sexual satisfaction, and marital satisfaction dimensions were closely related. Specifically, the avoidance dimension, but not the anxiety dimension, corresponded to lower levels of sexual and marital satisfaction. Moreover, for the sexual satisfaction variable, an interaction effect was observed between the gender of the actor and avoidance of the partner, which was observed only in men. In the marital satisfaction dimension, effects were apparent only at the individual level; a positive relation was found between the number of years spent living together and greater contentment with the relationship. These results confirm the hypothetical association between attachment and sexual and marital satisfaction and demonstrate the relevance of methodologies when the unit of analysis is the couple.
A supra-cellular model for coupling of bone resorption to formation during remodeling
DEFF Research Database (Denmark)
Jensen, Pia Rosgaard; Andersen, Thomas Levin; Pennypacker, Brenda L
2014-01-01
The bone matrix is maintained functional through the combined action of bone resorbing osteoclasts and bone forming osteoblasts, in so-called bone remodeling units. The coupling of these two activities is critical for securing bone replenishment and involves osteogenic factors released by the ost......The bone matrix is maintained functional through the combined action of bone resorbing osteoclasts and bone forming osteoblasts, in so-called bone remodeling units. The coupling of these two activities is critical for securing bone replenishment and involves osteogenic factors released...... osteoblasts from the canopy is induced by osteoclastic factors, thereby favoring initiation of bone formation. They lead to a model where the osteoclast-canopy interface is the physical site where coupling of bone resorption to bone formation occurs....
Zhu, Xiaolei; Yarkony, David R
2012-12-14
The analytic representation of adiabatic potential energy surfaces and their nonadiabatic interactions is a key component of accurate, fully quantum mechanical descriptions of nonadiabatic dynamics. In this work, we describe extensions of a promising method for representing the nuclear coordinate dependence of the energies, energy gradients, and derivative couplings of N(state) adiabatic electronic states coupled by conical intersections. The description is based on a vibronic coupling model and can describe multichannel dissociation. An important feature of this approach is that it incorporates information about the geometry dependent interstate derivative couplings into the fitting procedure so that the resulting representation is quantifiably quasi diabatic and quasi diabatic in a least squares sense. The reported extensions improve both the rate of convergence and the converged results and will permit the optimization of nonlinear parameters including those parameters that govern the placement of the functions used to describe multichannel dissociation. Numerical results for a coupled quasi-diabatic state representation of the photodissociation process NH(3)+hv → NH(2)+H illustrate the potential of the improved algorithm. A second focus in this numerical example is the quasi-diabatic character of the representation which is described and analyzed. Special attention is paid to the immediate vicinity of the conical intersection seam.
Larmat, C. S.; Rougier, E.; Delorey, A.; Steedman, D. W.; Bradley, C. R.
2016-12-01
The goal of the Source Physics Experiment (SPE) is to bring empirical and theoretical advances to the problem of detection and identification of underground nuclear explosions. For this, the SPE program includes a strong modeling effort based on first principles calculations with the challenge to capture both the source and near-source processes and those taking place later in time as seismic waves propagate within complex 3D geologic environments. In this paper, we report on results of modeling that uses hydrodynamic simulation codes (Abaqus and CASH) coupled with a 3D full waveform propagation code, SPECFEM3D. For modeling the near source region, we employ a fully-coupled Euler-Lagrange (CEL) modeling capability with a new continuum-based visco-plastic fracture model for simulation of damage processes, called AZ_Frac. These capabilities produce high-fidelity models of various factors believed to be key in the generation of seismic waves: the explosion dynamics, a weak grout-filled borehole, the surrounding jointed rock, and damage creation and deformations happening around the source and the free surface. SPECFEM3D, based on the Spectral Element Method (SEM) is a direct numerical method for full wave modeling with mathematical accuracy. The coupling interface consists of a series of grid points of the SEM mesh situated inside of the hydrodynamic code's domain. Displacement time series at these points are computed using output data from CASH or Abaqus (by interpolation if needed) and fed into the time marching scheme of SPECFEM3D. We will present validation tests with the Sharpe's model and comparisons of waveforms modeled with Rg waves (2-8Hz) that were recorded up to 2 km for SPE. We especially show effects of the local topography, velocity structure and spallation. Our models predict smaller amplitudes of Rg waves for the first five SPE shots compared to pure elastic models such as Denny &Johnson (1991).
A Multiscale, Mortar-Coupled Advection-Diffusion-Reaction Model for Biofilm Growth in Porous Media
Valocchi, A. J.; Laleian, A.; Werth, C. J.
2016-12-01
Multiscale models of reactive transport and biofilm growth in porous media are capable of capturing complex pore-scale processes while leveraging the efficiency of continuum-scale models. In particular, porosity and permeability changes caused by biofilm development result in complex feedbacks between transport and reaction that are difficult to quantify at the continuum scale. Pore-scale models are needed to accurately resolve these dynamics but are often impractical for applications due to their high computational cost. To address this challenge, we develop a multiscale model of biofilm growth in which non-overlapping regions at pore and continuum spatial scales are coupled with a mortar method that ensures continuity of flux across the interface. Thus, regions of high reactivity are resolved at the pore scale for accuracy while regions of low reactivity are resolved at the continuum scale for efficiency. By benchmarking the multiscale model against a fully pore-scale model, we find the multiscale model has a reduced run time while producing a consistent result in terms of biofilm growth, distribution, and solute utilization. We effectively extend a previous model by incorporating a multiscale flow solver and parallelizing solution of the computationally-intensive pore-scale component for increased scalability. We find that mortar coupling is a flexible and effective technique able to join differing computational grids and differing physics in adjacent regions for both fluid flow and solute transport. These results demonstrate the practicality of multiscale mortar-coupled models in studying the complexity of subsurface systems while considering computational limitations in their numerical solution. While recent work has demonstrated growing interest in the development of general multiscale models, more work is needed for their use in real-world applications. Our contribution is a step on the path toward accurate, efficient, and practical reactive transport
Energy Technology Data Exchange (ETDEWEB)
Zhao, Mei; Wang, Guomin; Hendon, Harry H.; Alves, Oscar [Bureau of Meteorology, Centre for Australian Weather and Climate Research, Melbourne (Australia)
2011-04-15
Impacts on the coupled variability of the Indo-Pacific by including the effects of surface currents on surface stress are explored in four extended integrations of an experimental version of the Bureau of Meteorology's coupled seasonal forecast model POAMA. The first pair of simulations differs only in their treatment of momentum coupling: one version includes the effects of surface currents on the surface stress computation and the other does not. The version that includes the effect of surface currents has less mean-state bias in the equatorial Pacific cold tongue but produces relatively weak coupled variability in the Tropics, especially that related to the Indian Ocean dipole (IOD) and El Nino/Southern Oscillation (ENSO). The version without the effects of surface currents has greater bias in the Pacific cold tongue but stronger IOD and ENSO variability. In order to diagnose the role of changes in local coupling from changes in remote forcing by ENSO for causing changes in IOD variability, a second set of simulations is conducted where effects of surface currents are included only in the Indian Ocean and only in the Pacific Ocean. IOD variability is found to be equally reduced by inclusion of the local effects of surface currents in the Indian Ocean and by the reduction of ENSO variability as a result of including effects of surface currents in the Pacific. Some implications of these results for predictability of the IOD and its dependence on ENSO, and for ocean subsurface data assimilation are discussed. (orig.)
Energy transfer in the nonequilibrium spin-boson model: From weak to strong coupling.
Liu, Junjie; Xu, Hui; Li, Baowen; Wu, Changqin
2017-07-01
To explore energy transfer in the nonequilibrium spin-boson model (NESB) from weak to strong system-bath coupling regimes, we propose a polaron-transformed nonequilibrium Green's function (NEGF) method. By combining the polaron transformation, we are able to treat the system-bath coupling nonperturbatively, thus in direct contrast to conventionally used NEGF methods which take the system-bath coupling as a perturbation. The Majorana-fermion representation is further utilized to evaluate terms in the Dyson series. This method not only allows us to deal with weak as well as strong coupling regimes but also enables an investigation on the role of bias in the energy transfer. As an application of the method, we study an Ohmic NESB. For an unbiased spin system, our energy current result smoothly bridges predictions of two benchmarks, namely, the quantum master equation and the nonequilibrium noninteracting blip approximation, a considerable improvement over existing theories. In case of a biased spin system, we found a bias-induced nonmonotonic behavior of the energy conductance in the intermediate coupling regime, resulting from the resonant character of the energy transfer. This finding may offer a nontrivial quantum control knob over energy transfer at the nanoscale.
Directory of Open Access Journals (Sweden)
V. P. Parhomenko
2015-01-01
Full Text Available The paper presents a realized hydrodynamic three-dimensional global climatic model, which comprises the model blocks of atmospheric general circulation, thermohaline large-scale circulation of the ocean, and sea ice evolution. Before rather strongly aggregated heat-moisturebalance model of the atmosphere for temperature and humidity of a surface layer was used as a model of the atmosphere. The atmospheric general circulation model is significantly more complicated and allows us to describe processes in the atmosphere more adequately. Functioning of a coupled climatic model is considered in conditions of the seasonal cycle of solar radiation.The paper considers a procedure for coupled calculation of the ocean model and atmospheric general circulation model. Synchronization of a number of parameters in both models is necessary for their joint action. In this regard a procedure of two-dimensional interpolation of data defined on the grids of the ocean model and atmosphere model and back is developed. A feature of this task is discrepancy of grid nodes and continental configurations in models. Coupled model-based long-term calculations for more than 400 years have shown its stable work. Calculation results and comparison with observation data are under discussion.The paper shows distribution of mean global atmosphere temperature versus time in stable conditions to demonstrate that there is inter-annual variability of atmosphere temperature at the steady state of a climate system. It presents distribution of temperature difference of the ocean surface from the observations and from the model of the ocean thermohaline circulation for January. Noticeable deviations of temperature are observed near Antarctica. Apparently, it is because of inaccurate calculation of the sea ice distribution in model. The geographical distribution of the ocean surface temperature for January with coupled calculation shows, in general, a zonal uniform structure of isolines
Zhang, Benfeng; Han, Tao; Tang, Gongbin; Zhang, Qiaozhen; Omori, Tatsuya; Hashimoto, Ken-Ya
2017-09-01
This paper discusses lateral propagation of surface acoustic waves (SAWs) in periodic grating structures when two types of SAWs exist simultaneously and are coupled. The thin plate model proposed by the authors is extended to include the coupling between two different SAW modes. First, lateral SAW propagation in an infinitely long periodic grating is modeled and discussed. Then, the model is applied to the Al-grating/42° YX-LiTaO3 (42-LT) substrate structure, and it is shown that the slowness curve shape changes from concave to convex with the Al grating thickness. The transverse responses are also analyzed on an infinitely long interdigital transducer on the structure, and good agreement is achieved between the present and the finite-element method analyses. Finally, SAW resonators are fabricated on the Cu grating/42-LT substrate structure, and it is experimentally verified that the slowness curve shape of the shear horizontal SAW changes with the Cu thickness.
Analyzing early exo-Earths with a coupled atmosphere biogeochemical model
Gebauer, Stefanie; Grenfell, John Lee; Stock, Joachim; Lehmann, Ralph; Godolt, Mareike; von Paris, Philip; Rauer, Heike
2017-04-01
Investigating Earth-like extrasolar planets with atmospheric models is a central focus in planetary science. Taking the development of Earth as a reference for Earth-like planets we investigate interactions between the atmosphere, planetary surface and organisms. The Great Oxidation Event (GOE) is related to feedbacks between these three. Its origin and controlling mechanisms are not well defined - requiring interdisciplinary, coupled models. We present results from our newly-developed Coupled Atmosphere Biogeochemistry (CAB) model which is unique in the literature. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles governing O2 in early Earth's atmosphere near the GOE. Complicated oxidation pathways play a key role in destroying O2 whereas in the upper atmosphere, most O2 is formed abiotically via CO2 photolysis.
Thermal Impedance Model of High Power IGBT Modules Considering Heat Coupling Effects
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
2014-01-01
Thermal loading of Insulated Gate Bipolar Transistor (IGBT) modules is important for the reliability performance of power electronic systems, thus the thermal information of critical points inside module like junction temperature must be accurately modeled and predicted. Usually in the existing...... thermal models, only the self-heating effects of the chips are taken into account, while the thermal coupling effects among chips are less considered. This could result in inaccurate temperature estimation, especially in the high power IGBT modules where the chips are allocated closely to each other...... with large amount of heat generated. In this paper, both the self-heating and heat-coupling effects in the of IGBT module are investigated based on Finite Element Method (FEM) simulation, a new thermal impedance model is thereby proposed to better describe the temperature distribution inside IGBT modules...
Small Signal Modeling and Comprehensive Analysis of Magnetically Coupled Impedance Source Converters
DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Blaabjerg, Frede
2016-01-01
Magnetically coupled impedance-source (MCIS) networks are recently introduced impedance networks intended for various high-boost applications. It employs coupled magnetic in the circuit to achieve higher voltage gain. Various MCIS networks have been proposed in the literature for myriad......-signal derivation is demonstrated for pulse width modulation (PWM) MCIS converters and it is shown that the derived transfer functions can simply be applied to Y-source, Γ-source, and T-source impedance networks. Various transfer functions for capacitor voltage, output voltage, magnetizing current, input and output...... applications; however, due to effective role of system modeling in the closed-loop controller design, this paper is allocated to small-signal modeling and analysis of MCIS converters. The modeling is performed by means of the circuit averaging and averaged switch technique. A generalized small...
Modelling of Rigid Walled Enclosure Couple to a Flexible Wall using Matlab and Ansys APDL
Zaman, I.; Rozlan, S. A. M.; Azmir, N. A.; Ismon, M.; Madlan, M. A.; Yahya, M. N.; Zainulabidin, M. H.; Sani, M. S. M.; Noh, M. F. M.
2017-10-01
Generally, solutions to improve the noise problems in enclosure are to redesign or modifying the system such as increasing the thickness of the wall panels, enhancing the elasticity of the structure, and increase the damping mechanism of the wall structure. In this paper, the application of vibroacoustic modelling of enclosure coupled to a flexible wall was presented. The sound pressure characteristics of rigid walled enclosure, such as natural frequency and mode shape were determined using two approaches which are finite element simulation of Ansys® and mathematical model. The mathematical equations derived in Matlab® such as rigid walled enclosure and rigid walled enclosure coupled to flexible wall were used to validate finite element analysis (FEA). The result indicates that the theory and FEA display in a good agreement. Thus, proved that the FE model was accurate and can be applied in further research such as sound pressure and noise attenuation in enclosure.
Small Signal Modeling and Comprehensive Analysis of Magnetically Coupled Impedance Source Converters
DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Blaabjerg, Frede
2016-01-01
applications; however, due to effective role of system modeling in the closed-loop controller design, this paper is allocated to small-signal modeling and analysis of MCIS converters. The modeling is performed by means of the circuit averaging and averaged switch technique. A generalized small......Magnetically coupled impedance-source (MCIS) networks are recently introduced impedance networks intended for various high-boost applications. It employs coupled magnetic in the circuit to achieve higher voltage gain. Various MCIS networks have been proposed in the literature for myriad......-signal derivation is demonstrated for pulse width modulation (PWM) MCIS converters and it is shown that the derived transfer functions can simply be applied to Y-source, Γ-source, and T-source impedance networks. Various transfer functions for capacitor voltage, output voltage, magnetizing current, input and output...
Tian, Tian; Salis, Howard M
2015-08-18
Natural and engineered genetic systems require the coordinated expression of proteins. In bacteria, translational coupling provides a genetically encoded mechanism to control expression level ratios within multi-cistronic operons. We have developed a sequence-to-function biophysical model of translational coupling to predict expression level ratios in natural operons and to design synthetic operons with desired expression level ratios. To quantitatively measure ribosome re-initiation rates, we designed and characterized 22 bi-cistronic operon variants with systematically modified intergenic distances and upstream translation rates. We then derived a thermodynamic free energy model to calculate de novo initiation rates as a result of ribosome-assisted unfolding of intergenic RNA structures. The complete biophysical model has only five free parameters, but was able to accurately predict downstream translation rates for 120 synthetic bi-cistronic and tri-cistronic operons with rationally designed intergenic regions and systematically increased upstream translation rates. The biophysical model also accurately predicted the translation rates of the nine protein atp operon, compared to ribosome profiling measurements. Altogether, the biophysical model quantitatively predicts how translational coupling controls protein expression levels in synthetic and natural bacterial operons, providing a deeper understanding of an important post-transcriptional regulatory mechanism and offering the ability to rationally engineer operons with desired behaviors. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.
A thermokinetic model for Mg-Si couple formation in Al-Mg-Si alloys
Svoboda, J.; Shan, Y. V.; Kozeschnik, E.; Fischer, F. D.
2016-03-01
Mg-Si couples formed from atomic Mg and Si represent the first step in Mg-Si cluster formation in a dilute Al-Mg-Si system. Based on the thermodynamic extremal principle, a kinetic model for Mg-Si couple formation is developed. The model utilizes the trapping concept for the calculation of Gibbs energy of the non-equilibrium system and provides a generalized (multiplicative) form of the Oriani equation for description of the equilibrium state. The dissipation in the system accounts for diffusion of both Mg and Si atoms in the lattice. The model is compared with the classical Lidiard and Howard equilibrium theory. Some demonstrative examples are presented. Finally the model is applied to an experimentally studied system. Good quantitative agreement with quenching experiments is obtained, if, simultaneously, the impact of excess quenched-in vacancies and their gradual annihilation in the system, which has been already treated in a previous paper, are accounted for. The model is generally applicable for any couple (and pair) formation.
Energy Technology Data Exchange (ETDEWEB)
Utgikar, Vivek [Univ. of Idaho, Moscow, ID (United States); Sun, Xiaodong [The Ohio State Univ., Columbus, OH (United States); Christensen, Richard [The Ohio State Univ., Columbus, OH (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-12-29
The overall goal of the research project was to model the behavior of the advanced reactorintermediate heat exchange system and to develop advanced control techniques for off-normal conditions. The specific objectives defined for the project were: 1. To develop the steady-state thermal hydraulic design of the intermediate heat exchanger (IHX); 2. To develop mathematical models to describe the advanced nuclear reactor-IHX-chemical process/power generation coupling during normal and off-normal operations, and to simulate models using multiphysics software; 3. To develop control strategies using genetic algorithm or neural network techniques and couple these techniques with the multiphysics software; 4. To validate the models experimentally The project objectives were accomplished by defining and executing four different tasks corresponding to these specific objectives. The first task involved selection of IHX candidates and developing steady state designs for those. The second task involved modeling of the transient and offnormal operation of the reactor-IHX system. The subsequent task dealt with the development of control strategies and involved algorithm development and simulation. The last task involved experimental validation of the thermal hydraulic performances of the two prototype heat exchangers designed and fabricated for the project at steady state and transient conditions to simulate the coupling of the reactor- IHX-process plant system. The experimental work utilized the two test facilities at The Ohio State University (OSU) including one existing High-Temperature Helium Test Facility (HTHF) and the newly developed high-temperature molten salt facility.
Feedback-Mediated Dynamics in a Model of Coupled Nephrons with Compliant Thick Ascending Limbs
Layton, Anita T.; Bowen, Matthew; Wen, Amy; Layton, Harold E.
2011-01-01
The tubuloglomerular feedback (TGF) system in the kidney, a key regulator of glomerular filtration rate, has been shown in physiologic experiments in rats to mediate oscillations in thick ascending limb (TAL) tubular fluid pressure, flow, and NaCl concentration. In spontaneously hypertensive rats, TGF-mediated flow oscillations may be highly irregular. We conducted a bifurcation analysis of a mathematical model of nephrons that are coupled through their TGF systems; the TALs of these nephrons are assumed to have compliant tubular walls. A characteristic equation was derived for a model of two coupled nephrons. Analysis of that characteristic equation has revealed a number of parameter regions having the potential for differing stable dynamic states. Numerical solutions of the full equations for two model nephrons exhibit a variety of behaviors in these regions. Also, model results suggest that the stability of the TGF system is reduced by the compliance of TAL walls and by internephron coupling; as a result, the likelihood of the emergence of sustained oscillations in tubular fluid pressure and flow is increased. Based on information provided by the characteristic equation, we identified parameters with which the model predicts irregular tubular flow oscillations that exhibit a degree of complexity that may help explain the emergence of irregular oscillations in spontaneously hypertensive rats. PMID:21329704
Energy Technology Data Exchange (ETDEWEB)
Miller, N.L.
1993-01-01
The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of necessary details about individual ecological community types or biomes and simulates the net momentum, heat, moisture, and trace gas fluxes. This suite of coupled models is defined here as the hierarchical systems flux scheme (HSFS).
Energy Technology Data Exchange (ETDEWEB)
Miller, N.L.
1993-12-31
The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of necessary details about individual ecological community types or biomes and simulates the net momentum, heat, moisture, and trace gas fluxes. This suite of coupled models is defined here as the hierarchical systems flux scheme (HSFS).
Thermochemical Nonequilibrium 2D Modeling of Nitrogen Inductively Coupled Plasma Flow
Yu, Minghao; Yusuke, Takahashi; Hisashi, Kihara; Ken-ichi, Abe; Kazuhiko, Yamada; Takashi, Abe; Satoshi, Miyatani
2015-09-01
Two-dimensional (2D) numerical simulations of thermochemical nonequilibrium inductively coupled plasma (ICP) flows inside a 10-kW inductively coupled plasma wind tunnel (ICPWT) were carried out with nitrogen as the working gas. Compressible axisymmetric Navier-Stokes (N-S) equations coupled with magnetic vector potential equations were solved. A four-temperature model including an improved electron-vibration relaxation time was used to model the internal energy exchange between electron and heavy particles. The third-order accuracy electron transport properties (3rd AETP) were applied to the simulations. A hybrid chemical kinetic model was adopted to model the chemical nonequilibrium process. The flow characteristics such as thermal nonequilibrium, inductive discharge, effects of Lorentz force were made clear through the present study. It was clarified that the thermal nonequilibrium model played an important role in properly predicting the temperature field. The prediction accuracy can be improved by applying the 3rd AETP to the simulation for this ICPWT. supported by Grant-in-Aid for Scientific Research (No. 23560954), sponsored by the Japan Society for the Promotion of Science
Koivumäki, Jussi T; Korhonen, Topi; Takalo, Jouni; Weckström, Matti; Tavi, Pasi
2009-01-01
Background The cardiomyocyte is a prime example of inherently complex biological system with inter- and cross-connected feedback loops in signalling, forming the basic properties of intracellular homeostasis. Functional properties of cells and tissues have been studied e.g. with powerful tools of genetic engineering, combined with extensive experimentation. While this approach provides accurate information about the physiology at the endpoint, complementary methods, such as mathematical modelling, can provide more detailed information about the processes that have lead to the endpoint phenotype. Results In order to gain novel mechanistic information of the excitation-contraction coupling in normal myocytes and to analyze sophisticated genetically engineered heart models, we have built a mathematical model of a mouse ventricular myocyte. In addition to the fundamental components of membrane excitation, calcium signalling and contraction, our integrated model includes the calcium-calmodulin-dependent enzyme cascade and the regulation it imposes on the proteins involved in excitation-contraction coupling. With the model, we investigate the effects of three genetic modifications that interfere with calcium signalling: 1) ablation of phospholamban, 2) disruption of the regulation of L-type calcium channels by calcium-calmodulin-dependent kinase II (CaMK) and 3) overexpression of CaMK. We show that the key features of the experimental phenotypes involve physiological compensatory and autoregulatory mechanisms that bring the system to a state closer to the original wild-type phenotype in all transgenic models. A drastic phenotype was found when the genetic modification disrupts the regulatory signalling system itself, i.e. the CaMK overexpression model. Conclusion The novel features of the presented cardiomyocyte model enable accurate description of excitation-contraction coupling. The model is thus an applicable tool for further studies of both normal and defective
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Weckström Matti
2009-08-01
Full Text Available Abstract Background The cardiomyocyte is a prime example of inherently complex biological system with inter- and cross-connected feedback loops in signalling, forming the basic properties of intracellular homeostasis. Functional properties of cells and tissues have been studied e.g. with powerful tools of genetic engineering, combined with extensive experimentation. While this approach provides accurate information about the physiology at the endpoint, complementary methods, such as mathematical modelling, can provide more detailed information about the processes that have lead to the endpoint phenotype. Results In order to gain novel mechanistic information of the excitation-contraction coupling in normal myocytes and to analyze sophisticated genetically engineered heart models, we have built a mathematical model of a mouse ventricular myocyte. In addition to the fundamental components of membrane excitation, calcium signalling and contraction, our integrated model includes the calcium-calmodulin-dependent enzyme cascade and the regulation it imposes on the proteins involved in excitation-contraction coupling. With the model, we investigate the effects of three genetic modifications that interfere with calcium signalling: 1 ablation of phospholamban, 2 disruption of the regulation of L-type calcium channels by calcium-calmodulin-dependent kinase II (CaMK and 3 overexpression of CaMK. We show that the key features of the experimental phenotypes involve physiological compensatory and autoregulatory mechanisms that bring the system to a state closer to the original wild-type phenotype in all transgenic models. A drastic phenotype was found when the genetic modification disrupts the regulatory signalling system itself, i.e. the CaMK overexpression model. Conclusion The novel features of the presented cardiomyocyte model enable accurate description of excitation-contraction coupling. The model is thus an applicable tool for further studies of both
Schmidtmann, I; Elsäßer, A; Weinmann, A; Binder, H
2014-12-30
For determining a manageable set of covariates potentially influential with respect to a time-to-event endpoint, Cox proportional hazards models can be combined with variable selection techniques, such as stepwise forward selection or backward elimination based on p-values, or regularized regression techniques such as component-wise boosting. Cox regression models have also been adapted for dealing with more complex event patterns, for example, for competing risks settings with separate, cause-specific hazard models for each event type, or for determining the prognostic effect pattern of a variable over different landmark times, with one conditional survival model for each landmark. Motivated by a clinical cancer registry application, where complex event patterns have to be dealt with and variable selection is needed at the same time, we propose a general approach for linking variable selection between several Cox models. Specifically, we combine score statistics for each covariate across models by Fisher's method as a basis for variable selection. This principle is implemented for a stepwise forward selection approach as well as for a regularized regression technique. In an application to data from hepatocellular carcinoma patients, the coupled stepwise approach is seen to facilitate joint interpretation of the different cause-specific Cox models. In conditional survival models at landmark times, which address updates of prediction as time progresses and both treatment and other potential explanatory variables may change, the coupled regularized regression approach identifies potentially important, stably selected covariates together with their effect time pattern, despite having only a small number of events. These results highlight the promise of the proposed approach for coupling variable selection between Cox models, which is particularly relevant for modeling for clinical cancer registries with their complex event patterns. Copyright © 2014 John Wiley & Sons
Kc, M.
2015-12-01
Ecosystem services and products are the foundation of sustainability for regional and global economy since we are directly or indirectly dependent on the ecosystem services like food, livestock, water, air, wildlife etc. It has been increasingly recognized that for sustainability concerns, the conservation problems need to be addressed in the context of entire ecosystems. This approach known as the ecosystem approach is fundamental to managing earth's finite resources since it addresses the interactions that link biotic systems, of which human, flora and fauna are integral parts, with the physical systems on which they depend. This approach is even more vital in the 21st century with formidable increasing human population and rapid changes in global environment. This study is being conducted to find the state of the science of ecosystem models in the South-Central region of US. The propose of the project is to conduct a systematic review and synthesize relevant information on the current state of the science of ecosystem modeling in the South-Central region of US toward coupling these models with climate, agronomic, hydrologic, economic or management models to better represent ecosystem dynamics as affected by climate change and human activities; and hence gain more reliable predictions of future ecosystem functions and service in the region. Better understandings of such processes will increase our ability to predict the ecosystem responses and feedbacks to environmental and human induced change in the region so that decision makers can make an informed management decisions of the ecosystem.
[Health Promoting Behavior in Pregnant Couples: Actor-Partner Interdependence Model Analysis].
Kim, Ju Hee; Song, Young A
2017-08-01
This study aimed to identify the actor and partner effects of self-efficacy, marital adjustment, and social support on the health promoting behavior of Korean pregnant couples. Participants were 132 couples who met the eligibility criteria. Data were collected from June to November, 2016 at a community health center. The Actor-Partner Interdependence Model was used for analyzing the actor and partner effects of self-efficacy, marital adjustment, and social support on health promoting behavior. The fitness indices for the model were GFI=0.90, NFI=0.92, CFI=0.91, TLI=0.90, and RMSEA=0.04, which satisfied the criteria. Self-efficacy had actor and partner effect on health promoting behavior of wives, but had only actor effect of on health promoting behavior of husbands. Marital adjustment showed actor and partner effect on the health promoting behavior of pregnant couples. Social support only had an actor effect on the health promoting behavior of wives. And, marital adjustment and social support had a mutual effect. This study indicates that the partner involvement is needed to develop health promotion programs for pregnant couples.
Inferring structural connectivity using Ising couplings in models of neuronal networks.
Kadirvelu, Balasundaram; Hayashi, Yoshikatsu; Nasuto, Slawomir J
2017-08-15
Functional connectivity metrics have been widely used to infer the underlying structural connectivity in neuronal networks. Maximum entropy based Ising models have been suggested to discount the effect of indirect interactions and give good results in inferring the true anatomical connections. However, no benchmarking is currently available to assess the performance of Ising couplings against other functional connectivity metrics in the microscopic scale of neuronal networks through a wide set of network conditions and network structures. In this paper, we study the performance of the Ising model couplings to infer the synaptic connectivity in in silico networks of neurons and compare its performance against partial and cross-correlations for different correlation levels, firing rates, network sizes, network densities, and topologies. Our results show that the relative performance amongst the three functional connectivity metrics depends primarily on the network correlation levels. Ising couplings detected the most structural links at very weak network correlation levels, and partial correlations outperformed Ising couplings and cross-correlations at strong correlation levels. The result was consistent across varying firing rates, network sizes, and topologies. The findings of this paper serve as a guide in choosing the right functional connectivity tool to reconstruct the structural connectivity.
Coupling dynamics and chemistry in the air pollution modelling of street canyons: A review.
Zhong, Jian; Cai, Xiao-Ming; Bloss, William James
2016-07-01
Air pollutants emitted from vehicles in street canyons may be reactive, undergoing mixing and chemical processing before escaping into the overlying atmosphere. The deterioration of air quality in street canyons occurs due to combined effects of proximate emission sources, dynamical processes (reduced dispersion) and chemical processes (evolution of reactive primary and formation of secondary pollutants). The coupling between dynamics and chemistry plays a major role in determining street canyon air quality, and numerical model approaches to represent this coupling are reviewed in this article. Dynamical processes can be represented by Computational Fluid Dynamics (CFD) techniques. The choice of CFD approach (mainly the Reynolds-Averaged Navier-Stokes (RANS) and Large-Eddy Simulation (LES) models) depends on the computational cost, the accuracy required and hence the application. Simplified parameterisations of the overall integrated effect of dynamics in street canyons provide capability to handle relatively complex chemistry in practical applications. Chemical processes are represented by a chemical mechanism, which describes mathematically the chemical removal and formation of primary and secondary species. Coupling between these aspects needs to accommodate transport, dispersion and chemical reactions for reactive pollutants, especially fast chemical reactions with time scales comparable to or shorter than those of typical turbulent eddies inside the street canyon. Different approaches to dynamical and chemical coupling have varying strengths, costs and levels of accuracy, which must be considered in their use for provision of reference information concerning urban canopy air pollution to stakeholders considering traffic and urban planning policies. Copyright © 2016 Elsevier Ltd. All rights reserved.
Radiative Yukawa couplings in the simplest left-right symmetric model
Gabrielli, Emidio; Marzola, Luca; Raidal, Martti
2017-02-01
We revisit a recent solution to the flavor hierarchy problem based on the paradigm that Yukawa couplings are, rather than fundamental constants, effective low energy couplings radiatively generated by interactions in a hidden sector of the theory. In the present paper we show that the setup required by this scenario can be set by gauge invariance alone, provided that the standard model gauge group be extended to the left-right symmetric group of S U (2 )L×S U (2 )R×U (1 )Y. The simplest scheme in which Yukawa couplings are forbidden at the tree-level organises the right-handed fermions into doublets and presents an additional Higgs S U (2 )R doublet, responsible for the spontaneous breaking of the S U (2 )R gauge sector. The flavor and chiral symmetry breaking induced by the S U (2 )R breaking is transferred at the one-loop level to the standard model via the dynamics of the hidden sector, which effectively regulates the spread of the effective Yukawa couplings. The emerging left-right symmetric framework recovers additional appealing features typical of these models, allowing for instance to identify the hypercharges of the involved fermions with their B -L charges and offering a straightforward solution to the strong C P problem. The scheme gives rise to a distinguishing phenomenology that potentially can be tested at the LHC and future colliders through the same interactions that result in the radiative generation of Yukawa couplings, as well as by exploiting the properties of the additional S U (2 )R Higgs doublet.
O'Neill, B. C.; Lawrence, P.; Ren, X.
2016-12-01
Collaboration between the integrated assessment modeling (IAM) and earth system modeling (ESM) communities is increasing, driven by a growing interest in research questions that require analysis integrating both social and natural science components. This collaboration often takes the form of integrating their respective models. There are a number of approaches available to implement this integration, ranging from one-way linkages to full two-way coupling, as well as approaches that retain a single modeling framework but improve the representation of processes from the other framework. We discuss the pros and cons of these different approaches and the conditions under which a two-way coupling of IAMs and ESMs would be favored over a one-way linkage. We propose a criterion that is necessary and sufficient to motivate two-way coupling: A human process must have an effect on an earth system process that is large enough to cause a change in the original human process that is substantial compared to other uncertainties in the problem being investigated. We then illustrate a test of this criterion for land use-climate interactions based on work using the Community Earth System Model (CESM) and land use scenarios from the Representative Concentration Pathways (RCPs), in which we find that the land use effect on regional climate is unlikely to meet the criterion. We then show an example of implementing a one-way linkage of land use and agriculture between an IAM, the integrated Population-Economy-Technology-Science (iPETS) model, and CESM that produces fully consistent outcomes between iPETS and the CESM land surface model. We use the linked system to model the influence of climate change on crop yields, agricultural land use, crop prices and food consumption under two alternative future climate scenarios. This application demonstrates the ability to link an IAM to a global land surface and climate model in a computationally efficient manner.
Directory of Open Access Journals (Sweden)
Qiang WEI
2017-08-01