Effect of Coriolis coupling in chemical reaction dynamics.
Chu, Tian-Shu; Han, Ke-Li
2008-05-14
It is essential to evaluate the role of Coriolis coupling effect in molecular reaction dynamics. Here we consider Coriolis coupling effect in quantum reactive scattering calculations in the context of both adiabaticity and nonadiabaticity, with particular emphasis on examining the role of Coriolis coupling effect in reaction dynamics of triatomic molecular systems. We present the results of our own calculations by the time-dependent quantum wave packet approach for H + D2 and F(2P3/2,2P1/2) + H2 as well as for the ion-molecule collisions of He + H2 +, D(-) + H2, H(-) + D2, and D+ + H2, after reviewing in detail other related research efforts on this issue.
Coriolis coupling and nonadiabaticity in chemical reaction dynamics.
Wu, Emilia L
2010-12-01
The nonadiabatic quantum dynamics and Coriolis coupling effect in chemical reaction have been reviewed, with emphasis on recent progress in using the time-dependent wave packet approach to study the Coriolis coupling and nonadiabatic effects, which was done by K. L. Han and his group. Several typical chemical reactions, for example, H+D(2), F+H(2)/D(2)/HD, D(+)+H(2), O+H(2), and He+H(2)(+), have been discussed. One can find that there is a significant role of Coriolis coupling in reaction dynamics for the ion-molecule collisions of D(+)+H(2), Ne+H(2)(+), and He+H(2)(+) in both adiabatic and nonadiabatic context.
Amyay, Badr; Robert, Séverine; Herman, Michel; Fayt, André; Raghavendra, Balakrishna; Moudens, Audrey; Thiévin, Jonathan; Rowe, Bertrand; Georges, Robert
2009-09-21
A high temperature source has been developed and coupled to a high resolution Fourier transform spectrometer to record emission spectra of acetylene around 3 mum up to 1455 K under Doppler limited resolution (0.015 cm(-1)). The nu(3)-ground state (GS) and nu(2)+nu(4)+nu(5) (Sigma(u) (+) and Delta(u))-GS bands and 76 related hot bands, counting e and f parities separately, are assigned using semiautomatic methods based on a global model to reproduce all related vibration-rotation states. Significantly higher J-values than previously reported are observed for 40 known substates while 37 new e or f vibrational substates, up to about 6000 cm(-1), are identified and characterized by vibration-rotation parameters. The 3 811 new or improved data resulting from the analysis are merged into the database presented by Robert et al. [Mol. Phys. 106, 2581 (2008)], now including 15 562 lines accessing vibrational states up to 8600 cm(-1). A global model, updated as compared to the one in the previous paper, allows all lines in the database to be simultaneously fitted, successfully. The updates are discussed taking into account, in particular, the systematic inclusion of Coriolis interaction.
Analytical treatment of Coriolis coupling for three-body systems
NASA Astrophysics Data System (ADS)
Poirier, Bill
2005-01-01
In a previous article [J. Chem. Phys. 108 (1998) 5216], an efficient method was presented for performing "exact" quantum calculations for the three-body rovibrational Hamiltonian, within the helicity-conserving approximation. This approach makes use of a certain three-body "effective potential," enabling the same bend angle basis set to be employed for all values of the rotational quantum numbers, J, K and M. In the present work, the method is extended to incorporate Coriolis coupling, for which the relevant matrix elements are derived exactly. These can be used to solve the full three-body rovibrational problem, in the standard Jacobi coordinate vector embedding. Generalization of the method for coupled kinetic energy operators arising from other coordinate systems, embeddings, and/or system sizes, is also discussed.
Coriolis-coupled wave packet dynamics of H + HLi reaction.
Padmanaban, R; Mahapatra, S
2006-05-11
We investigated the effect of Coriolis coupling (CC) on the initial state-selected dynamics of H+HLi reaction by a time-dependent wave packet (WP) approach. Exact quantum scattering calculations were obtained by a WP propagation method based on the Chebyshev polynomial scheme and ab initio potential energy surface of the reacting system. Partial wave contributions up to the total angular momentum J=30 were found to be necessary for the scattering of HLi in its vibrational and rotational ground state up to a collision energy approximately 0.75 eV. For each J value, the projection quantum number K was varied from 0 to min (J, K(max)), with K(max)=8 until J=20 and K(max)=4 for further higher J values. This is because further higher values of K do not have much effect on the dynamics and also because one wishes to maintain the large computational overhead for each calculation within the affordable limit. The initial state-selected integral reaction cross sections and thermal rate constants were calculated by summing up the contributions from all partial waves. These were compared with our previous results on the title system, obtained within the centrifugal sudden and J-shifting approximations, to demonstrate the impact of CC on the dynamics of this system.
Coriolis effects and motion sickness modelling.
Bles, W
1998-11-15
Coriolis effects are notorious in relation to disorientation and motion sickness in aircrew. A review is provided of experimental data on these Coriolis effects, including the modulatory effects of adding visual or somatosensory rotatory motion information. A vector analysis of the consequences of head movements during somatosensory, visual and/or vestibular rotatory motion stimulation revealed that the more the sensed angular velocity vector after the head movements is aligned with the gravitoinertial force vector, the less nauseating effects are experienced. It is demonstrated that this is a special case of the subjective vertical conflict theory on motion sickness that assumes that motion sickness may be provoked if a discrepancy is detected between the subjective vertical and the sensed vertical as determined on the basis of incoming sensory information.
Vansteenkiste, P; Van Neck, D; Van Speybroeck, V; Waroquier, M
2006-01-28
Large-amplitude motions, particularly internal rotations, are known to affect substantially thermodynamic functions and rate constants of reactions in which flexible molecules are involved. Up to now all methods for computing the partition functions of these motions rely on the Pitzer approximation of more than 50 years ago, in which the large-amplitude motion is treated in complete independence of the other (vibrational) degrees of freedom. In this paper an extended hindered-rotor model (EHR) is developed in which the vibrational modes, treated harmonically, are correctly separated from the large-amplitude motion and in which relaxation effects (the changes in the kinetic-energy matrix and potential curvature) are taken into account as one moves along the large-amplitude path. The model also relies on a specific coordinate system in which the Coriolis terms vanish at all times in the Hamiltonian. In this way an increased level of consistency between the various internal modes is achieved, as compared with the more usual hindered-rotor (HR) description. The method is illustrated by calculating the entropies and heat capacities on 1,3-butadiene and 1-butene (with, respectively, one and two internal rotors) and the rate constant for the addition reaction of a vinyl radical to ethene. We also discuss various variants of the one-dimensional hindered-rotor scheme existing in the literature and its relation with the EHR model. It is argued why in most cases the HR approach is already quite successful.
The Coriolis Effect: A Model for Student Involvement
ERIC Educational Resources Information Center
Exline, Joseph D.
1977-01-01
Lists materials and procedures for constructing a model that demonstrates certain aspects of the Coriolis effect. Materials include an electric drill motor, voltage control, toy dart gun and darts, wood blocks of varying dimensions. Includes description of an experiment illustrating relationship between speed of rotation and amount of apparent…
The Coriolis Effect: A Model for Student Involvement
ERIC Educational Resources Information Center
Exline, Joseph D.
1977-01-01
Lists materials and procedures for constructing a model that demonstrates certain aspects of the Coriolis effect. Materials include an electric drill motor, voltage control, toy dart gun and darts, wood blocks of varying dimensions. Includes description of an experiment illustrating relationship between speed of rotation and amount of apparent…
NASA Technical Reports Server (NTRS)
Lackner, J. R.; Graybiel, A.
1986-01-01
The effect of gravity on the severity of the Coriolis-induced motion sickness was investigated in ten individuals subjected to high and low G-force phases of parabolic flight maneuvers using constant level Coriolis, cross-coupled angular acceleration stimulation. Using seven levels of severity in the diagnosis of motion sickness, it was found that the subjects were less susceptible at 0 G than at +2 Gz, and that the perceived intensity and provocativeness of Coriolis stimulation decreased in 0 G and increased in +2 Gz relative to the +1 Gz baseline values. The changes in the apparent intensity of Coriolis stimulation occur virtually immediately when the background gravitatioinertial force level is varied. These findings explain why the Skylab astronauts were refractory to motion sickness during Coriolis stimulation in-flight.
Direct transitions from high-K isomers to low-K bands -- {gamma} softness or coriolis coupling
Shimizu, Yoshifumi R.; Narimatsu, Kanako; Ohtsubo, Shin-Ichi
1996-12-31
Recent measurements of direct transitions from high-K isomers to low-K bands reveal severe break-down of the K-selection rule and pose the problem of how to understand the mechanism of such K-violation. The authors recent systematic calculations by using a simple {gamma}-tunneling model reproduced many of the observed hindrances, indicating the importance of the {gamma} softness. However, there are some data which cannot be explained in terms of the {gamma}-degree of freedom. In this talk, the authors also discuss the results of conventional Coriolis coupling calculations, which is considered to be another important mechanism.
The Coriolis-Coupled States v(6) = 1 and v(8) = 1 of DCOOH.
Baskakov; Alanko; Koivusaari
1999-11-01
The Fourier transform gas-phase infrared spectra of the Coriolis-perturbed nu(6) and nu(8) bands of deuterated formic acid DCOOH were measured with a resolution of ca. 0.003 cm(-1). Combined analysis of the 8977 IR transitions and all the available rotational data (from literature) in the ground state, as well as in the excited vibrational states v(6) = 1 and v(8) = 1 was carried out. The Coriolis coupling terms were determined and improved sets of rotational and centrifugal distortion parameters for the ground and excited vibrational states were obtained. The determined band centers are nu(0) (nu(8)) = 873.385046(12) cm(-1) and nu(0) (nu(6)) = 970.8889551(46) cm(-1). Copyright 1999 Academic Press.
Helicopter rotor lag damping augmentation based on a radial absorber and Coriolis coupling
NASA Astrophysics Data System (ADS)
Byers, Lynn Karen
A radial vibration absorber is proposed to augment rotor lag damping. Modeled as a discrete mass restrained by a damped spring and moving along the spanwise direction within the rotor blade, it introduces damping into the lag mode of the blade through strong Coriolis coupling. A two-degree-of-freedom model is developed and used to examine the effectiveness of the radial absorber in transferring damping to the rotor lag mode. Results demonstrate that it is possible to introduce a significant amount of damping in the lag mode with a relatively small absorber mass, and the corresponding amplitudes of 1/rev periodic motions are not excessively large. The lag mode damping and 1/rev motions are also compared with the results achieved for an embedded chordwise inertial damper. A classical six-degree-of-freedom aeromechanical stability analysis is augmented with two absorber cyclic degrees of freedom in the nonrotating frame to examine the effect of the radial absorber on aeromechanical stability characteristics. These results indicate that ground resonance instability is eliminated for the range of absorber parameters considered, and in most cases, the stability margins are significant. A rotor blade with a discrete radial vibration absorber is also analyzed to examine the effect of the absorber on rotor blade and hub loads. The rotor blade is modeled as an elastic beam undergoing flap and lag bending, with the absorber modeled as a discrete mass restrained by a damped spring, moving in the spanwise direction within the rotor blade. Results indicate that the addition of the absorber does not detrimentally affect the blade spanwise and root loads, as well as steady and vibratory hub loads. Finally, device concepts and implementation possibilities are considered for the embedded radial vibration absorber.
Microwave spectrum, structure, dipole moment, and Coriolis coupling of 1,1-difluoroallene
NASA Technical Reports Server (NTRS)
Durig, J. R.; Li, Y. S.; Tong, C. C.; Zens, A. P.; Ellis, P. D.
1974-01-01
Microwave spectra from 12.4 to 40.0 GHz were recorded for five isotopic species of 1,1-difluoroallene. A-type transitions were observed and R-branch assignments were made for the ground state and two vibrationally excited states. Several structural parameters of the compounds were determined. The dipole moment value obtained from Stark splitting was 2.07 plus or minus 0.03 D. A Coriolis coupling was observed between the two-low-frequency C = C = C bending modes.
Vestibular coriolis effect differences modeled with three-dimensional linear-angular interactions.
Holly, Jan E
2004-01-01
The vestibular coriolis (or "cross-coupling") effect is traditionally explained by cross-coupled angular vectors, which, however, do not explain the differences in perceptual disturbance under different acceleration conditions. For example, during head roll tilt in a rotating chair, the magnitude of perceptual disturbance is affected by a number of factors, including acceleration or deceleration of the chair rotation or a zero-g environment. Therefore, it has been suggested that linear-angular interactions play a role. The present research investigated whether these perceptual differences and others involving linear coriolis accelerations could be explained under one common framework: the laws of motion in three dimensions, which include all linear-angular interactions among all six components of motion (three angular and three linear). The results show that the three-dimensional laws of motion predict the differences in perceptual disturbance. No special properties of the vestibular system or nervous system are required. In addition, simulations were performed with angular, linear, and tilt time constants inserted into the model, giving the same predictions. Three-dimensional graphics were used to highlight the manner in which linear-angular interaction causes perceptual disturbance, and a crucial component is the Stretch Factor, which measures the "unexpected" linear component.
Lattanzi; di Lauro C
1999-12-01
The mechanism of torsional Coriolis interaction of E(1d) and E(2d) vibrational modes in ethane-like molecules is investigated, and it is shown that this coupling can drastically affect the torsional splitting in the degenerate vibrational states. A basic point of our treatment is that the sets of coordinates of head and tail which combine with the + sign to generate E(1d) normal coordinates are in general different from those which combine with the - sign to generate E(2d) normal coordinates. It is shown that the zeta(gamma) torsional Coriolis coefficients calculated by the usual methods of normal mode analysis are related to the vibrational angular momenta within head and tail referred to the internal rotor axis systems. With knowledge of the L and L(-1) matrices it is possible to transform these coefficients for reference to the molecule-fixed frame. It is peculiar that torsional Coriolis matrix elements occur between E(1d) and E(2d) vibrational components with the same x or y orientation in the molecule-fixed frame. The matrix elements of the torsional Coriolis operator and other operators responsible for the end-to-end coupling are determined, and a method for calculating vibration-torsion energies, and then torsional splittings, in degenerate vibrational states is outlined. Detailed calculations require a global model, involving all the degenerate vibrational basis states in a complex mechanism of interactions, but it is shown that useful information can be obtained by means of simplified models. Our semiempirical rule that degenerate vibrational states with a large negative value of the diagonal vibration-rotation Coriolis coefficient are likely to deviate much from the behavior of E(1d) or E(2d) vibrational states, with a sensible decrease of the torsional splittings, is confirmed. Copyright 1999 Academic Press.
Yang, Huan; Han, Keli; Schatz, George C; Smith, Sean C; Hankel, Marlies
2010-10-21
We present exact quantum differential cross sections and exact and estimated integral cross sections and branching ratios for the title reaction. We employ a time-dependent wavepacket method as implemented in the DIFFREALWAVE code including all Coriolis couplings and also an adapted DIFFREALWAVE code where the helicity quantum number and with this the Coriolis couplings have been truncated. Our exact differential cross sections at 0.453 eV total energy, one of the experimental energies, show good agreement with the experimental results for one of the product channels. While the truncated calculation present a significant reduction in the computational effort needed they overestimate the exact integral cross sections.
NASA Astrophysics Data System (ADS)
Li, Song; Zheng, Rui; Zhu, Yu; Duan, Chuanxi
2011-10-01
Four internal-rotation/vibration bands of the Ne-D2O complex have been measured in the v2 bend region of D2O using a tunable infrared diode laser spectrometer to probe a slit supersonic expansion. Three ortho bands are excited from the ground state Σ(000) to the Σ and Π(111, υ2 = 1) internal rotor states and the n = 1, Σ(000, υ2 = 1) stretching-internal rotor combination state. Strong perturbations between the excited vibrational states are evident. The observed spectra are analyzed separately with a three-state J-dependent Coriolis plus J-independent angular-radial coupling model [M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 106, 3078 (1997), 10.1063/1.473051] and a three-state Coriolis coupling model [R. C. Cohen and R. J. Saykally, J. Chem. Phys. 95, 7891 (1991), 10.1063/1.461318]. The former model works more successfully than the latter. Molecular constants for the ground and excited vibrational states of ortho 20Ne-D2O isotopomer as well as the Coriolis and angular-radial coupling constants are determined accurately. The van der Waals stretching frequency is estimated to be νs = 24.85 cm-1 in the ground state and decreases to about 20.8 cm-1 upon vibrational excitation of the D2O bend.
Li, Song; Zheng, Rui; Zhu, Yu; Duan, Chuanxi
2011-10-07
Four internal-rotation/vibration bands of the Ne-D(2)O complex have been measured in the v(2) bend region of D(2)O using a tunable infrared diode laser spectrometer to probe a slit supersonic expansion. Three ortho bands are excited from the ground state Σ(0(00)) to the Σ and Π(1(11), υ(2) = 1) internal rotor states and the n = 1, Σ(0(00), υ(2) = 1) stretching-internal rotor combination state. Strong perturbations between the excited vibrational states are evident. The observed spectra are analyzed separately with a three-state J-dependent Coriolis plus J-independent angular-radial coupling model [M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 106, 3078 (1997)] and a three-state Coriolis coupling model [R. C. Cohen and R. J. Saykally, J. Chem. Phys. 95, 7891 (1991)]. The former model works more successfully than the latter. Molecular constants for the ground and excited vibrational states of ortho (20)Ne-D(2)O isotopomer as well as the Coriolis and angular-radial coupling constants are determined accurately. The van der Waals stretching frequency is estimated to be ν(s) = 24.85 cm(-1) in the ground state and decreases to about 20.8 cm(-1) upon vibrational excitation of the D(2)O bend.
Linear thermal circulator based on Coriolis forces.
Li, Huanan; Kottos, Tsampikos
2015-02-01
We show that the presence of a Coriolis force in a rotating linear lattice imposes a nonreciprocal propagation of the phononic heat carriers. Using this effect we propose the concept of Coriolis linear thermal circulator which can control the circulation of a heat current. A simple model of three coupled harmonic masses on a rotating platform permits us to demonstrate giant circulating rectification effects for moderate values of the angular velocities of the platform.
Importance of Coriolis Coupling in Isotopic Branching in (He, HD+) collisions.
Tiwari, Ashwani Kumar; Kolakkandy, Sujitha; Sathyamurthy, N
2009-08-27
A three-dimensional time-dependent quantum mechanical wave packet approach is used to calculate the reaction probability (P(R)) and integral reaction cross section values for both channels of the reaction He + HD(+)(v = 1; j = 0) --> HeH (D)(+) + D (H) over a range of translational energy (E(trans)) on the McLaughlin-Thompson-Joseph-Sathyamurthy potential energy surface including the Coriolis coupling (CC) term in the Hamiltonian. The reaction probability plots as a function of translational energy for different J values exhibit several oscillations, which are characteristic of the system. The sigma(R) values obtained by including CC and not including it are nearly the same over the range of E(trans) investigated for the HeD(+) channel. For the HeH(+) channel, on the other hand, sigma(R) values obtained from CC calculations are significantly smaller than those obtained from coupled state calculations. These results are compared with the available experimental results. The computed branching ratios (Gamma(sigma) = sigma(R) (HeH(+))/sigma(R) (HeD(+))) are also compared with the available experimental results.
Lack of gender difference in motion sickness induced by vestibular Coriolis cross-coupling.
Cheung, Bob; Hofer, Kevin
It has been reported that females are more susceptible to motion sickness than males. Supporting evidence is primarily based on retrospective survey questionnaires and self-reporting. We investigated if there is a gender difference in motion sickness susceptibility using objective and subjective measurements under controlled laboratory conditions. Thirty healthy subjects (14 males and 16 females) between the ages of 18-46 years were exposed to Coriolis cross-coupling stimulation, induced by 120 degrees /s yaw rotation and a simultaneous 45 degrees pitch forward head movement in the sagittal plane every 12 seconds. Cutaneous forearm and calf blood flow, blood pressure, and heart rate were monitored. Graybiel's diagnostic criteria were used to assess sickness susceptibility before and after motion exposure. Golding and Kerguelen's scale was used to assess the severity of symptoms during motion exposure. A significant (p<0.01) increase of forearm and calf blood flow during cross-coupling stimulation was observed in both sexes. However, the subjective symptoms rating and blood flow measurements indicate that there was no significant difference between male and female subjects. Our data also suggests that females may be more inclined to admit discomfort as indicated by their responses to a survey of motion sickness history prior to the experiment.
Hankel, M
2011-05-07
We present exact and estimated quantum differential and integral cross sections as well as product state distributions for the title reaction. We employ a time-dependent wavepacket method including all Coriolis couplings and also an adapted code where the helicity quantum number and with this the Coriolis couplings have been truncated. Results from helicity truncated as well as helicity conserving (HC) calculation are presented. The HC calculations fail to reproduce the exact results due to the influence of the centrifugal barrier. While the truncated calculation overestimate the exact integral cross sections they reproduce the features of the integral cross section very well. We also find that the product rotational state distributions are well reproduced if the maximum helicity state is chosen carefully. The helicity truncated calculations fail to give a good approximation of differential cross sections.
NASA Technical Reports Server (NTRS)
Valentinuzzi, M.
1973-01-01
Phase lag, maximal slow phase velocity, and beat frequency were measured in periodic Coriolis star nystagmus. The results have been described by Steinhausen's model of the semicircular canal system. Estimates of the biophysical constants have been obtained. It is concluded that this model is a good functional approximation for describing, and also for interpreting, the behavior of the system.
Kobayashi, A; Cheung, B
2006-02-13
Near infrared spectroscopy (NIRS) has been successful in monitoring cerebral haemodynamics when the subject is immobilized during surgery, and when there is a drastic depletion of blood from the cerebral cortex during positive acceleration. In this study, we monitored subtle changes of cerebral oxygen level using NIRS during vestibular stimulation. For the control conditions, cerebral oxygen status was monitored in six stationary subjects sitting upright, and while they executed head movements in the pitch axis with eyes opened and eyes closed. The experimental conditions involved the subjects making a head movement which required a 45 degrees pitch-down followed by a return to upright head movements 12 s later during yaw rotation (Coriolis cross coupling) at 10 and 20 rotations per minute (rpm) in a random order. Oxyhaemoglobin (O(2)Hb), deoxyhaemoglobin (HHb) and total haemoglobin levels were recorded every 0.5 s from both the parietal and the occipital lobe simultaneously. A significant rotation effect was observed in total Hb level changes from baseline in both regions. Occipital O(2)Hb increased significantly after the head movement with eyes opened at 20 rpm. Our findings appear to be consistent with previous vestibular studies that significant changes in brain blood flow occur during caloric stimulation. NIRS can be used to monitor discrete cortical blood flow changes resulting from vestibular and other forms of stimulation.
Axis-Switching and Coriolis Coupling in the Ã(010)- X˜(000) Transitions of DCCl and HCCl
NASA Astrophysics Data System (ADS)
Lin, Ao; Kobayashi, Kaori; Yu, Hua-Gen; Hall, Gregory E.; Muckerman, James T.; Sears, Trevor J.; Merer, Anthony J.
2002-08-01
The rotationally resolved Ã(010)- X˜(000) spectrum of DCCl between 12 880 and 12 964 cm -1 was measured using frequency-modulated laser absorption spectroscopy of jet-cooled and ambient temperature samples. Transitions to levels with Ka'=0 and 1 were assigned, and their analysis leads to improved accuracy of both the ground state rotational constants of DCCl and, when combined with existing data for HCCl, the geometry of the radical. In addition to the expected perpendicular band structure, a number of parallel (Δ Ka=0) subbands were observed. Their intensity derives from a combination of c-type Coriolis coupling and axis-switching (J. T. Hougen and J. K. G. Watson, 1965, Can. J. Phys.43, 298) resulting from the change in geometry between the two states. The two contributions have been calculated for the (010)-(000) band of DCCl and previously recorded data for HCCl. Satisfactory agreement with experimental measurements was obtained. The Coriolis contributions are small for these transitions, but may add to or subtract from the axis-switching. For higher bending excitation in the upper state, Coriolis coupling is predicted to make larger contributions to the parallel subband intensities.
The Coriolis-Coupled States v7 = 1 and v9 = 1 of trans-HCOOD and trans-DCOOD.
Baskakov; Bürger; Jerzembeck
1999-01-01
The Fourier transform gas-phase infrared spectra of the two lowest Coriolis-perturbed nu7 and nu9 bands of deuterated formic acid HCOOD and DCOOD have been measured with a resolution of ca. 0.003 cm-1. Combined analysis of the assigned IR transitions and all the available rotational data have allowed the determination of the band centers, rotational and centrifugal distortion parameters, and Coriolis coupling terms. Standard deviations of the IR transitions are 0.000246 cm-1 for HCOOD and 0.000209 cm-1 for DCOOD. Determined band centers are nu0(nu7) = 558.2723 cm-1, nu0(nu9) = 508.1321 cm-1 for HCOOD and nu0(nu7) = 554.4397 cm-1, nu0(nu9) = 492.2254 cm-1 for DCOOD. Copyright 1999 Academic Press.
NASA Astrophysics Data System (ADS)
Borges, E.; Ferreira, G. G.; Braga, J. P.; Belchior, J. C.
Classical trajectories studies in Cartesian coordinates are applied to analyze Coriolis coupling for the energy transfer in H2O + Ar process. Vibrational energies equal to 50 kcal/mol and 100 kcal/mol for initial rotational temperatures in the range 298-30,000 K are used as initial conditions. Initial translational temperatures for the incoming atom are selected in the same way. Effects of rotational and translational temperatures at different initial conditions are also investigated in the molecular vibrational relaxation process.
NASA Technical Reports Server (NTRS)
Dizio, Paul; Lackner, James R.; Evanoff, John N.
1987-01-01
The goal of the present experiment was to determine whether gravitoinertial force magnitude influences oculomotor and perceptual responses to Coriolis cross-coupling stimulation. Blindfolded subjects who were rotating at constant velocity were asked to make standardized head movements during the free-fall and high-force phases of parabolic flight, and the characteristics of their horizontal nystagmus and the magnitude of their experienced self-motion were measured. Both responses were less intense in the free-fall periods than in the high-force periods. These findings suggest that the response to semicircular canal stimulation depends on the background level of gravitoinertial force.
Modeling, design, fabrication and characterization of a micro Coriolis mass flow sensor
NASA Astrophysics Data System (ADS)
Haneveld, J.; Lammerink, T. S. J.; de Boer, M. J.; Sanders, R. G. P.; Mehendale, A.; Lötters, J. C.; Dijkstra, M.; Wiegerink, R. J.
2010-12-01
This paper discusses the modeling, design and realization of micromachined Coriolis mass flow sensors. A lumped element model is used to analyze and predict the sensor performance. The model is used to design a sensor for a flow range of 0-1.2 g h-1 with a maximum pressure drop of 1 bar. The sensor was realized using semi-circular channels just beneath the surface of a silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. Special comb-shaped electrodes are integrated on the channels for capacitive readout of the extremely small Coriolis displacements. The comb-shaped electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods. Furthermore, it prevents squeezed film damping due to a thin layer of air between the capacitor electrodes. As a result, the sensor operates at atmospheric pressure with a quality factor in the order of 40 and does not require vacuum packaging like other micro Coriolis flow sensors. Measurement results using water, ethanol, white gas and argon are presented, showing that the sensor measures true mass flow. The measurement error is currently in the order of 1% of the full scale of 1.2 g h-1.
Chu, Tian-Shu; Han, Ke-Li; Hankel, Marlies; Balint-Kurti, Gabriel G
2007-06-07
The quantum wavepacket parallel computational code DIFFREALWAVE is used to calculate state-to-state integral and differential cross sections for the title reaction on the BKMP2 surface in the total energy range of 0.4-1.2 eV with D2 initially in its ground vibrational-rotational state. The role of Coriolis couplings in the state-to-state quantum calculations is examined in detail. Comparison of the results from calculations including the full Coriolis coupling and those using the centrifugal sudden approximation demonstrates that both the energy dependence and the angular dependence of the calculated cross sections are extremely sensitive to the Coriolis coupling, thus emphasizing the importance of including it correctly in an accurate state-to-state calculation.
NASA Astrophysics Data System (ADS)
Marciuc, Daly; Solschi, Viorel
2017-04-01
Understanding the Coriolis effect is essential for explaining the movement of air masses and ocean currents. The lesson we propose aims to familiarize students with the manifestation of the Coriolis effect. Students are guided to build, using the GeoGebra software, a simulation of the motion of a body, related to a rotating reference system. The mathematical expression of the Coriolis force is deduced, for particular cases, and the Foucault's pendulum is presented and explained. Students have the opportunity to deepen the subject, by developing materials related to topics such as: • Global Wind Pattern • Ocean Currents • Coriolis Effect in Long Range Shooting • Finding the latitude with a Foucault Pendulum
NASA Astrophysics Data System (ADS)
Fan, J. F.; Juang, H. M. H.
2015-12-01
In most numerical weather prediction models, the cosine terms of the Coriolis force are omitted due to the use of shallow-atmosphere approximation with the angular momentum principle. However, by applying the non-hydrostatic deep momentum system, we can omit the angular momentum principle for regional modeling, while leaving the cosine terms, to calculate the full-component Coriolis force. From the governing equations, we can see that the cosine terms of the Coriolis force affect zonal wind (u) and vertical wind (w). The magnitude of the Coriolis force is determined by two factors: wind speed and latitude. The maximum of the cosine function happens when the latitude is zero degrees, which is at the equator. In this study, we conduct research into the effects of full-component Coriolis force in the nonhydrostatic regional spectral model (RSM) over tropical areas. Numerical experiments will be done to show the impact of the cosine terms of Coriolis force on wind field and precipitation structure. The differences in the two approaches will be compared in order to prove their relative effectiveness in climate prediction.
Moss; Duan; Jacobson; O'Brien; Field
2000-02-01
Stimulated emission pumping (SEP) spectroscopy has been used to examine a low energy region (E(vib) approximately 4400 cm(-1)) of &Xtilde;(1)Sigma(+)(g) acetylene at higher resolution than was possible in previous dispersed fluorescence studies. The expected bright state, nu(2) + 4nu(4), is observed to be coupled to the nearly degenerate 7nu(4) state by a Coriolis mechanism. A least-squares analysis yields values for zero-order vibrational energies, rotational constants, and a Coriolis-coupling coefficient that are all consistent with expectations. Calculated relative intensities of SEP transitions, accounting for interference due to axis-switching effects, are also consistent with observations. Implications of the observed Coriolis resonance with regard to global acetylene vibrational dynamics are also discussed. Copyright 2000 Academic Press.
Coriolis coupling effects on the initial-state-resolved dynamics of the N(2D)+H2-->NH+H reaction.
Defazio, Paolo; Petrongolo, Carlo
2007-11-28
We present Coriolis coupling effects on the initial-state-resolved dynamics of the insertion reaction N((2)D)+H(2)(X (1)Sigma(g) (+))-->NH(X (3)Sigma(-) and a (1)Delta)+H((2)S), without and with nonadiabatic Renner-Teller (RT) interactions between the NH(2) X (2)B(1) and A (2)A(1) electronic states. We report coupled-channel (CC) Hamiltonian matrix elements, which take into account both Coriolis and RT couplings, use the real wave-packet and flux methods for calculating initial-state-resolved reaction probabilities, and contrast CC with centrifugal-sudden (CS) results. Without RT interactions, Coriolis effects are rather small up to J=40, and the CS approximation can be safely employed for calculating initial-state-resolved, integral cross sections. On the other hand, RT effects are associated with rather large Coriolis couplings, mainly near the linearity of NH(2), and the accuracy of the CS approximation thus breaks down at high collision energies, when the reaction starts on the excited A (2)A(1) surface. We also present the CC-RT distribution of the X (3)Sigma(-) and a (1)Delta electronic states of the NH products.
Kryvohuz, M; Marcus, R A
2010-06-14
A classical theory is proposed to describe the non-RRKM effects in activated asymmetric top triatomic molecules observed numerically in classical molecular dynamics simulations of ozone. The Coriolis coupling is shown to result in an effective diffusive energy exchange between the rotational and vibrational degrees of freedom. A stochastic differential equation is obtained for the K-component of the rotational angular momentum that governs the diffusion.
Sensitivities of Modeled Tropical Cyclones to Surface Friction and the Coriolis Parameter
NASA Technical Reports Server (NTRS)
Chao, Winston C.; Chen, Baode; Tao, Wei-Kuo; Lau, William K. M. (Technical Monitor)
2002-01-01
In this investigation the sensitivities of a 2-D tropical cyclone (TC) model to surface frictional coefficient and the Coriolis parameter are studied and their implication is discussed. The model used is an axisymmetric version of the latest version of the Goddard cloud ensemble model. The model has stretched vertical grids with 33 levels varying from 30 m near the bottom to 1140 m near the top. The vertical domain is about 21 km. The horizontal domain covers a radius of 962 km (770 grids) with a grid size of 1.25 km. The time step is 10 seconds. An open lateral boundary condition is used. The sea surface temperature is specified at 29C. Unless specified otherwise, the Coriolis parameter is set at its value at 15 deg N. The Newtonian cooling is used with a time scale of 12 hours. The reference vertical temperature profile used in the Newtonian cooling is that of Jordan. The Newtonian cooling models not only the effect of radiative processes but also the effect of processes with scale larger than that of TC. Our experiments showed that if the Newtonian cooling is replaced by a radiation package, the simulated TC is much weaker. The initial condition has a temperature uniform in the radial direction and its vertical profile is that of Jordan. The initial winds are a weak Rankin vortex in the tangential winds superimposed on a resting atmosphere. The initial sea level pressure is set at 1015 hPa everywhere. Since there is no surface pressure perturbation, the initial condition is not in gradient balance. This initial condition is enough to lead to cyclogenesis, but the initial stage (say, the first 24 hrs) is not considered to resemble anything observed. The control experiment reaches quasi-equilibration after about 10 days with an eye wall extending from 15 to 25 km radius, reasonable comparing with the observations. The maximum surface wind of more than 70 m/s is located at about 18 km radius. The minimum sea level pressure on day 10 is about 886 hPa. Thus the
NASA Technical Reports Server (NTRS)
Chao, Winston C.; Chen, Baode; Tao, Wei-Kuo; Lau, William K. M. (Technical Monitor)
2002-01-01
The sensitivities to surface friction and the Coriolis parameter in tropical cyclogenesis are studied using an axisymmetric version of the Goddard cloud ensemble model. Our experiments demonstrate that tropical cyclogenesis can still occur without surface friction. However, the resulting tropical cyclone has very unrealistic structure. Surface friction plays an important role of giving the tropical cyclones their observed smaller size and diminished intensity. Sensitivity of the cyclogenesis process to surface friction. in terms of kinetic energy growth, has different signs in different phases of the tropical cyclone. Contrary to the notion of Ekman pumping efficiency, which implies a preference for the highest Coriolis parameter in the growth rate if all other parameters are unchanged, our experiments show no such preference.
Estimation of Coriolis Force and Torque Acting on Ares-1
NASA Technical Reports Server (NTRS)
Mackey, Ryan M.; Kulikov, Igor K.; Smelyanskiy, Vadim; Luchinsky, Dmitry; Orr, Jeb
2011-01-01
A document describes work on the origin of Coriolis force and estimating Coriolis force and torque applied to the Ares-1 vehicle during its ascent, based on an internal ballistics model for a multi-segmented solid rocket booster (SRB).
Bane, Michael K; Robertson, Evan G; Thompson, Christopher D; Medcraft, Chris; Appadoo, Dominique R T; McNaughton, Don
2011-06-21
High resolution FTIR spectra of the short lived species ketenimine have been recorded in the regions 390-1300 cm(-1) and 20-110 cm(-1) using synchrotron radiation. Two thousand six hundred sixty transitions of the ν(7) band centered at 693 cm(-1) and 126 far-IR rotational transitions have been assigned. Rotational and centrifugal distortion parameters for the ν(7) mode were determined and local Fermi and b-axis Coriolis interactions with 2ν(12) are treated. A further refinement of the ground state, ν(12) and ν(8) parameters was also achieved, including the treatment of previously unrecognized ac-axis and ab-axis second order perturbations to the ground state.
Measurement of oscillopsia induced by vestibular Coriolis stimulation.
Sanderson, Jeffrey; Oman, Charles M; Harris, Laurence R
2007-01-01
We demonstrate a new method for measuring the time constant of head-movement-contingent oscillopsia (HMCO) produced by vestibular Coriolis stimulation. Subjects briskly rotated their heads around pitch or roll axes whilst seated on a platform rotating at constant velocity. This induced a cross-coupled vestibular Coriolis illusion. Simultaneous with the head movement, a visual display consisting of either a moving field of white dots on a black background or superimposed on a subject-stationary horizon, or a complete virtual room with conventional furnishings appeared. The scene's motion was driven by a simplified computer model of the Coriolis illusion. Subjects either nulled (if visual motion was against the illusory body rotation) or matched (if motion was in the same direction as the illusory motion) the sensation with the exponentially slowing scene motion, by indicating whether its decline was too fast or too slow. The model time constant was approximated using a staircase technique. Time constants comparable to that of the Coriolis vestibular ocular reflex were obtained. Time constants could be significantly reduced by adding subject-stationary visual elements. This technique for measuring oscillopsia might be used to quantify adaptation to artificial gravity environments. In principle more complex models can be used, and applied to other types of oscillopsia such as are experienced by BPPV patients or by astronauts returning to Earth.
Debunking Coriolis Force Myths
ERIC Educational Resources Information Center
Shakur, Asif
2014-01-01
Much has been written and debated about the Coriolis force. Unfortunately, this has done little to demystify the paradoxes surrounding this fictitious force invoked by an observer in a rotating frame of reference. It is the purpose of this article to make another valiant attempt to slay the dragon of the Coriolis force! This will be done without…
Debunking Coriolis Force Myths
ERIC Educational Resources Information Center
Shakur, Asif
2014-01-01
Much has been written and debated about the Coriolis force. Unfortunately, this has done little to demystify the paradoxes surrounding this fictitious force invoked by an observer in a rotating frame of reference. It is the purpose of this article to make another valiant attempt to slay the dragon of the Coriolis force! This will be done without…
NASA Astrophysics Data System (ADS)
Wang, Lijuan; Yan, Yong; Wang, Xue; Wang, Tao
2017-03-01
Input variable selection is an essential step in the development of data-driven models for environmental, biological and industrial applications. Through input variable selection to eliminate the irrelevant or redundant variables, a suitable subset of variables is identified as the input of a model. Meanwhile, through input variable selection the complexity of the model structure is simplified and the computational efficiency is improved. This paper describes the procedures of the input variable selection for the data-driven models for the measurement of liquid mass flowrate and gas volume fraction under two-phase flow conditions using Coriolis flowmeters. Three advanced input variable selection methods, including partial mutual information (PMI), genetic algorithm-artificial neural network (GA-ANN) and tree-based iterative input selection (IIS) are applied in this study. Typical data-driven models incorporating support vector machine (SVM) are established individually based on the input candidates resulting from the selection methods. The validity of the selection outcomes is assessed through an output performance comparison of the SVM based data-driven models and sensitivity analysis. The validation and analysis results suggest that the input variables selected from the PMI algorithm provide more effective information for the models to measure liquid mass flowrate while the IIS algorithm provides a fewer but more effective variables for the models to predict gas volume fraction.
ERIC Educational Resources Information Center
Lissaman, P. B. S.
1979-01-01
Detailed are the history, development, and future objectives of the Coriolis program, a project designed to place large turbine units in the Florida Current that would generate large amounts of electric power. (BT)
ERIC Educational Resources Information Center
Lissaman, P. B. S.
1979-01-01
Detailed are the history, development, and future objectives of the Coriolis program, a project designed to place large turbine units in the Florida Current that would generate large amounts of electric power. (BT)
Yao, Cui-Xia; Zhang, Pei-Yu
2014-07-10
The dynamics of the Ne + D2(+) (v0 = 0-2, j0 = 0) → NeD(+) + D reaction has been investigated in detail by using an accurate time-dependent wave-packet method on the ground 1(2)A' potential energy surface. Comparisons between the Coriolis coupling results and the centrifugal-sudden ones reveal that Coriolis coupling effect can influence reaction dynamics of the NeD2(+) system. Integral cross sections have been evaluated for the Ne + D2(+) reaction and its isotopic variant Ne + H2(+), and a considerable intermolecular isotopic effect has been found. Also obvious is the great enhancement of the reactivity due to the reagent vibrational excitation. Besides, a comparison with previous theoretical results is also presented and discussed.
Concept of Linear Thermal Circulator Based on Coriolis forces
NASA Astrophysics Data System (ADS)
Li, Huanan; Kottos, Tsampikos
2015-03-01
Directional transport and the creation of non-reciprocal devices that control the flow of energy and/or mass at predefined directions have been posing always fascinating challenges. In this contribution, we show that the presence of a Coriolis force in a rotating linear lattice imposes a non-reciprocal propagation of the phononic heat carriers. Using this effect we propose the concept of Coriolis linear thermal circulator which can control the circulation of a heat current. A simple model of three coupled harmonic masses on a rotating platform allow us to demonstrate giant circulating rectification effects for moderate values of the angular velocities of the platform. This work was partly sponsored by a NSF DMR-1306984 Grant and by an AFOSR MURI Grant FA9550-14-1-0037.
Mechanics of Coriolis stimulus and inducing factors of motion sickness.
Isu, N; Shimizu, T; Sugata, K
2001-12-01
To specify inducing factors of motion sickness comprised in Coriolis stimulus, or cross-coupled rotation, the sensation of rotation derived from the semicircular canal system during and after Coriolis stimulus under a variety of stimulus conditions, was estimated by an approach from mechanics with giving minimal hypotheses and simplifications on the semicircular canal system and the sensory nervous system. By solving an equation of motion of the endolymph during Coriolis stimulus, rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then the sensation derived from the whole semicircular canal system was particularly considered in two cases of a single Coriolis stimulus and cyclic Coriolis stimuli. The magnitude and the direction of sensation of rotation were shown to depend on an angular velocity of body rotation and a rotating angle of head movement (amplitude of head oscillation when cyclic Coriolis stimuli) irrespective of initial angle (center angle) of the head relative to the vertical axis. The present mechanical analysis of Coriolis stimulus led a suggestion that the severity of nausea evoked by Coriolis stimulus is proportional to the effective value of the sensation of rotation caused by the Coriolis stimulus.
NASA Astrophysics Data System (ADS)
Stoppa, Paolo; Tasinato, Nicola; Baldacci, Agostino; Pietropolli Charmet, Andrea; Giorgianni, Santi; Tamassia, Filippo; Cané, Elisabetta; Villa, Mattia
2016-05-01
The FTIR spectra of CH2F2 have been investigated in a region of atmospheric interest (1000-1300 cm-1) where four fundamentals ν3, ν5, ν7 and ν9 occur. These vibrations perturb each other by different Coriolis interactions and the forbidden ν5 borrows intensity from the neighboring levels. Furthermore, the v4=2 state has been found to interact with the v3=1 and v9=1 states by anharmonic and c-type Coriolis resonances, respectively. The spectral analysis resulted in the assignment of about 7500 rovibrational transitions which have been simultaneously fitted, together with microwave data available in literature (Hirota E. J Mol Spectrosc 1978; 69: 409-420) [15] using the Watson's A-reduction Hamiltonian in the Ir representation and the relevant perturbation operators. The model employed includes eight types of resonances within the pentad ν3/ν5/ν7/ν9/2ν4. A set of spectroscopic constants for the four fundamentals as well as parameters for the v4=2 state and eighteen coupling terms have been determined. The simulations performed in different spectral regions well reproduce the experimental data.
ERIC Educational Resources Information Center
Levi, F. A.
1988-01-01
Describes a demonstration of Coriolis acceleration. Discusses two different meanings of "Coriolis" and two causes of Coriolis acceleration. Gives a set-up method of the demonstration apparatus by using a rotary disk with rubber tubing for tap water, switches, lamps, battery, and counterweight. Provides two pictures with operating method.…
ERIC Educational Resources Information Center
Levi, F. A.
1988-01-01
Describes a demonstration of Coriolis acceleration. Discusses two different meanings of "Coriolis" and two causes of Coriolis acceleration. Gives a set-up method of the demonstration apparatus by using a rotary disk with rubber tubing for tap water, switches, lamps, battery, and counterweight. Provides two pictures with operating method.…
Merer, Anthony J; Yamakita, Nami; Tsuchiya, Soji; Steeves, Adam H; Bechtel, Hans A; Field, Robert W
2008-08-07
Rotational analyses have been carried out for the overtones of the nu(4) (torsion) and nu(6) (in-plane cis-bend) vibrations of the A (1)A(u) state of C(2)H(2). The v(4)+v(6)=2 vibrational polyad was observed in high-sensitivity one-photon laser-induced fluorescence spectra and the v(4)+v(6)=3 polyad was observed in IR-UV double resonance spectra via the ground state nu(3) (Sigma(+) (u)) and nu(3)+nu(4) (Pi(u)) vibrational levels. The structures of these polyads are dominated by the effects of vibrational angular momentum: Vibrational levels of different symmetry interact via strong a-and b-axis Coriolis coupling, while levels of the same symmetry interact via Darling-Dennison resonance, where the interaction parameter has the exceptionally large value K(4466)=-51.68 cm(-1). The K-structures of the polyads bear almost no resemblance to the normal asymmetric top patterns, and many local avoided crossings occur between close-lying levels with nominal K-values differing by one or more units. Least squares analysis shows that the coupling parameters change only slightly with vibrational excitation, which has allowed successful predictions of the structures of the higher polyads: A number of weak bands from the v(4)+v(6)=4 and 5 polyads have been identified unambiguously. The state discovered by Scherer et al. [J. Chem. Phys. 85, 6315 (1986)], which appears to interact with the K=1 levels of the 3(3) vibrational state at low J, is identified as the second highest of the five K=1 members of the v(4)+v(6)=4 polyad. After allowing for the Darling-Dennison resonance, the zero-order bending structure can be represented by omega(4)=764.71, omega(6)=772.50, x(44)=0.19, x(66)=-4.23, and x(46)=11.39 cm(-1). The parameters x(46) and K(4466) are both sums of contributions from the vibrational angular momentum and from the anharmonic force field. For x(46) these contributions are 14.12 and -2.73 cm(-1), respectively, while the corresponding values for K(4466) are -28.24 and -23
Dynamics of viscous fingers in rotating Hele-Shaw cells with Coriolis effects.
Gadêlha, Hermes; Brito, Nielison; Miranda, José A
2007-01-01
A growing number of experimental and theoretical works have been addressing various aspects of the viscous fingering formation in rotating Hele-Shaw cells. However, only a few of them consider the influence of Coriolis forces. The studies including Coriolis effects are mostly restricted to the high-viscosity-contrast limit and rely on either purely linear stability analyses or intensive numerical simulations. We approach the problem analytically and use a modified Darcy's law including the exact form of the Coriolis effects to execute a mode-coupling analysis of the system. By imposing no restrictions on the viscosity contrast A (dimensionless viscosity difference) we go beyond linear stages and examine the onset of nonlinearities. Our results indicate that when Coriolis effects are taken into account, an interesting interplay between the Reynolds number Re and A arises. This leads to important changes in the stability and morphological features of the emerging interfacial patterns. We contrast our mode-coupling approach with previous theoretical models proposed in the literature.
Coriolis effects are principally caused by gyroscopic angular acceleration.
Isu, N; Yanagihara, M; Mikuni, T; Koo, J
1994-07-01
A cause of nausea evoked by cross-coupled rotation (termed Coriolis stimulus) was determined. Subjects were provided with two types of cross-coupled rotations: neck-forward flexion (Neck Flx) and upper body-forward flexion (Body Flx) during horizontal whole body rotation at a constant angular velocity. These Coriolis stimuli were given alternatively in an experimental sequence, and the severity of the nausea they evoked was compared by the subjects. The results indicated that the same quality of nausea was evoked by a slightly higher angular velocity during Body Flx (100.5 degrees/s) than during Neck Flx (90 degrees/s). While Body Flx generated Coriolis linear acceleration several times larger than Neck Flx, both the stimuli generated a similar magnitude of gyroscopic angular acceleration in this condition. Therefore, it was inferred that the nausea evoked by a Coriolis stimulus is principally caused by gyroscopic angular acceleration.
Gamallo, Pablo; Defazio, Paolo; González, Miguel
2011-10-27
The Ne + H(2)(+)(v(0) = 0-4, j(0) = 1) proton transfer reaction has been studied in a wide collision energy (E(col)) interval, using the time dependent real wave packet method and taking into account the Coriolis coupling (CC-RWP method) and employing a recent ab initio potential energy surface, widely extending the reaction conditions previously explored at the CC level. The reaction probability shows a strong oscillatory behavior vs E(col) and the presence of sharp resonances, arising from metastable NeH(2)(+) states. The behavior of the reaction cross section σ vs E(col) depends on the vibrational level and can in general be interpreted in terms of the late barrier character of the potential energy surface and the existence (or not) of threshold energy. The situation is particularly complex for v(0) = 2, as σ(v0=2, j0=1) presents significant oscillations with E(col) up to ≈0.33 eV, which probably reflect the resonances found in the reaction probability. Hence, it would be particularly interesting to investigate the Ne + H(2)(+)(v(0) = 2, j(0) = 1) reaction experimentally, as some resonances survive the partial wave summation. The state selected cross sections compare well with previous CC quantum and experimental results, and although the previous centrifugal sudden RWP cross sections are reasonable, the inclusion of the Coriolis coupling is important to achieve a quantitative description of this and similar systems.
Lu, Ruifeng; Wang, Yunhui; Deng, Kaiming
2013-07-30
The quantum mechanics (QM) and quasiclassical trajectory (QCT) calculations have been carried out for the title reaction with the ground minimal allowed rotational state of CH (j = 1) on the 1 (1)A' potential energy surface. For the reaction probability at total angular momentum J = 0, a similar trend of the QM and QCT calculations is observed, and the QM results are larger than the latter almost in the whole considered energy range (0.1-1.5 eV). The QCT integral cross sections are larger than the QM results with centrifugal sudden approximation, while smaller than those from QM method including Coriolis coupling for collision energies bigger than 0.25 eV. The quantum wave-packet computations show that the Coriolis coupling effects get more and more pronounced with increasing of J. In addition to the scalar properties, the stereodynamical properties, such as the average rotational alignment factor
Xu, Wenwu; Li, Wenliang; Lv, Shuangjiang; Zhai, Hongsheng; Duan, Zhixin; Zhang, Peiyu
2012-11-15
The time-dependent wave packet quantum method taking into account the Coriolis coupling (CC) has been employed to investigate the dynamics of O(+) + H(2)/D(2)/HD (v(i) = 0, j(i) = 0) reactions based on an accurate potential energy surface [ Martínez et al. J. Chem. Phys. 2004 , 120 , 4705 ]. Through the comparison between the results with and without CC, the pronounced CC effects have been revealed in the title reactions. Moreover, the calculated results with the CC method can well reproduce the data of close-coupling hyperspherical (CCH) exact quantum method. The calculations demonstrate that the CC effects play an important role in the O(+) + H(2) system.
Lin, Shi Ying; Sun, Zhigang; Guo, Hua; Zhang, Dong Hui; Honvault, Pascal; Xie, Daiqian; Lee, Soo-Y
2008-01-31
We present accurate quantum calculations of the integral cross section and rate constant for the H + O2 --> OH + O combustion reaction on a recently developed ab initio potential energy surface using parallelized time-dependent and Chebyshev wavepacket methods. Partial wave contributions up to J = 70 were computed with full Coriolis coupling, which enabled us to obtain the initial state-specified integral cross sections up to 2.0 eV of the collision energy and thermal rate constants up to 3000 K. The integral cross sections show a large reaction threshold due to the quantum endothermicity of the reaction, and they monotonically increase with the collision energy. As a result, the temperature dependence of the rate constant is of the Arrhenius type. In addition, it was found that reactivity is enhanced by reactant vibrational excitation. The calculated thermal rate constant shows a significant improvement over that obtained on the DMBE IV potential, but it still underestimates the experimental consensus.
Exposing the Bathtub Coriolis Myth.
ERIC Educational Resources Information Center
Salzsieder, John C.
1994-01-01
Presents a demonstration that employs angular momentum to disprove the myth that water spirals down a bathtub drain clockwise in one hemisphere and counterclockwise in the other because of the Coriolis force on water. (ZWH)
Exposing the Bathtub Coriolis Myth.
ERIC Educational Resources Information Center
Salzsieder, John C.
1994-01-01
Presents a demonstration that employs angular momentum to disprove the myth that water spirals down a bathtub drain clockwise in one hemisphere and counterclockwise in the other because of the Coriolis force on water. (ZWH)
Coriolis attenuation in the A congruent 130--150 region
Saha, M.; Goswami, A.; Bhattacharya, S.; Sen, S. )
1990-10-01
The particle-rotor model has been applied to calculate the band structure in a number of highly neutron deficient odd-{ital A} rare-earth nuclei in the {ital A}{congruent}130--150 region. Several transitional nuclei are also included in the study. The only adjustable parameter, used in the calculation, is the Coriolis attenuation coefficient. However, it is seen that the observed band structures in these nuclei can be reproduced practically without any {ital ad} {ital hoc} reduction of the Coriolis matrix elements. The systematics of the Coriolis attenuation in the neutron-deficient, transitional, and well-deformed rare-earth nuclei are discussed in the light of the present work and several theoretical studies, made earlier. The importance of the pairing interaction in the Coriolis attenuation study is emphasized.
Using the Model Coupling Toolkit to couple earth system models
Warner, J.C.; Perlin, N.; Skyllingstad, E.D.
2008-01-01
Continued advances in computational resources are providing the opportunity to operate more sophisticated numerical models. Additionally, there is an increasing demand for multidisciplinary studies that include interactions between different physical processes. Therefore there is a strong desire to develop coupled modeling systems that utilize existing models and allow efficient data exchange and model control. The basic system would entail model "1" running on "M" processors and model "2" running on "N" processors, with efficient exchange of model fields at predetermined synchronization intervals. Here we demonstrate two coupled systems: the coupling of the ocean circulation model Regional Ocean Modeling System (ROMS) to the surface wave model Simulating WAves Nearshore (SWAN), and the coupling of ROMS to the atmospheric model Coupled Ocean Atmosphere Prediction System (COAMPS). Both coupled systems use the Model Coupling Toolkit (MCT) as a mechanism for operation control and inter-model distributed memory transfer of model variables. In this paper we describe requirements and other options for model coupling, explain the MCT library, ROMS, SWAN and COAMPS models, methods for grid decomposition and sparse matrix interpolation, and provide an example from each coupled system. Methods presented in this paper are clearly applicable for coupling of other types of models. ?? 2008 Elsevier Ltd. All rights reserved.
Defazio, Paolo; Bussery-Honvault, Béatrice; Honvault, Pascal; Petrongolo, Carlo
2011-09-21
The Renner-Teller (RT) coupled-channel dynamics for the C((1)D)+H(2)(X(1)Σ(g) (+))→CH(X(2)Π)+H((2)S) reaction has been investigated for the first time, considering the first two singlet states ã̃(1)A' and b(1)A'' of CH(2) dissociating into the products and RT couplings, evaluated through the ab initio matrix elements of the electronic angular momentum. We have obtained initial-state-resolved probabilities, cross sections and thermal rate constants via the real wavepacket method for both coupled electronic states. In contrast to the N((2)D)+H(2)(X(1)Σ(g)(+)) system, RT effects tend to reduce probabilities, cross sections, and rate constants in the low energy range compared to Born-Oppenheimer (BO) ones, due to the presence of a repulsive RT barrier in the effective potentials and to long-lived resonances. Furthermore, contrary to BO results, the rate constants have a positive temperature dependence in the 100-400 K range. The two-state RT rate constant at 300 K, lower than the BO one, remains inside the error bars of the experimental value.
Peeters, A G; Angioni, C; Strintzi, D
2007-06-29
In this Letter, the influence of the "Coriolis drift" on small scale instabilities in toroidal plasmas is shown to generate a toroidal momentum pinch velocity. Such a pinch results because the Coriolis drift generates a coupling between the density and temperature perturbations on the one hand and the perturbed parallel flow velocity on the other. A simple fluid model is used to highlight the physics mechanism and gyro-kinetic calculations are performed to accurately assess the magnitude of the pinch. The derived pinch velocity leads to a radial gradient of the toroidal velocity profile even in the absence of a torque on the plasma and is predicted to generate a peaking of the toroidal velocity profile similar to the peaking of the density profile. Finally, the pinch also affects the interpretation of current experiments.
Measurement of Coriolis Acceleration with a Smartphone
ERIC Educational Resources Information Center
Shaku, Asif; Kraft, Jakob
2016-01-01
Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern…
Measurement of Coriolis Acceleration with a Smartphone
ERIC Educational Resources Information Center
Shaku, Asif; Kraft, Jakob
2016-01-01
Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern…
Measurement of Coriolis Acceleration with a Smartphone
NASA Astrophysics Data System (ADS)
Shakur, Asif; Kraft, Jakob
2016-05-01
Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern smartphones come with a raft of built-in sensors, we have a unique opportunity to experimentally determine the Coriolis acceleration conveniently in a pedagogically enlightening environment at modest cost by using student-owned smartphones. Here we employ the gyroscope and accelerometer in a smartphone to verify the dependence of Coriolis acceleration on the angular velocity of a rotatingtrack and the speed of the sliding smartphone.
Rapid adaptation to Coriolis force perturbations of arm trajectory
NASA Technical Reports Server (NTRS)
Lackner, J. R.; Dizio, P.
1994-01-01
line to the wrong place. Aftereffects of opposite sign were transiently present in the postrotary movements. 5. These observations fail to support current equilibrium point models, both alpha and lambda, of movement control. Such theories would not predict endpoint errors under our experimental conditions, in which the Coriolis force is absent at the beginning and end of a movement. Our results indicate that detailed aspects of movement trajectory are being continuously monitored on the basis of proprioceptive feedback in relation to motor commands. Adaptive compensations can be initiated after one perturbation despite the absence of either visual or tactile feedback about movement trajectory and endpoint error. Moreover, movement trajectory and end-point can be remapped independently.(ABSTRACT TRUNCATED AT 400 WORDS).
Rapid adaptation to Coriolis force perturbations of arm trajectory.
Lackner, J R; Dizio, P
1994-07-01
line to the wrong place. Aftereffects of opposite sign were transiently present in the postrotary movements. 5. These observations fail to support current equilibrium point models, both alpha and lambda, of movement control. Such theories would not predict endpoint errors under our experimental conditions, in which the Coriolis force is absent at the beginning and end of a movement. Our results indicate that detailed aspects of movement trajectory are being continuously monitored on the basis of proprioceptive feedback in relation to motor commands. Adaptive compensations can be initiated after one perturbation despite the absence of either visual or tactile feedback about movement trajectory and endpoint error. Moreover, movement trajectory and end-point can be remapped independently.(ABSTRACT TRUNCATED AT 400 WORDS)
Warne, Larry Kevin; Chen, Kenneth C.
2004-03-01
This report assembles models for the response of a wire interacting with a conducting ground to an electromagnetic pulse excitation. The cases of an infinite wire above the ground as well as resting on the ground and buried beneath the ground are treated. The focus is on the characteristics and propagation of the transmission line mode. Approximations are used to simplify the description and formulas are obtained for the current. The semi-infinite case, where the short circuit current can be nearly twice that of the infinite line, is also examined.
The competition between Lorentz and Coriolis forces in planetary dynamos
NASA Astrophysics Data System (ADS)
Soderlund, Krista M.; Sheyko, Andrey; King, Eric M.; Aurnou, Jonathan M.
2015-12-01
Fluid motions within planetary cores generate magnetic fields through dynamo action. These core processes are driven by thermo-compositional convection subject to the competing influences of rotation, which tends to organize the flow into axial columns, and the Lorentz force, which tends to inhibit the relative movement of the magnetic field and the fluid. It is often argued that these forces are predominant and approximately equal in planetary cores; we test this hypothesis using a suite of numerical geodynamo models to calculate the Lorentz to Coriolis force ratio directly. Our results show that this ratio can be estimated by ( Λ i is the traditionally defined Elsasser number for imposed magnetic fields and Rm is the system-scale ratio of magnetic induction to magnetic diffusion). Best estimates of core flow speeds and magnetic field strengths predict the geodynamo to be in magnetostrophic balance where the Lorentz and Coriolis forces are comparable. The Lorentz force may also be significant, i.e., within an order of magnitude of the Coriolis force, in the Jovian interior. In contrast, the Lorentz force is likely to be relatively weak in the cores of Saturn, Uranus, Neptune, Ganymede, and Mercury.
NASA Technical Reports Server (NTRS)
Subrahmanyam, K. B.; Kaza, K. R. V.; Brown, G. V.; Lawrence, C.
1986-01-01
The coupled bending-bending-torsional equations of dynamic motion of rotating, linearly pretwisted blades are derived including large precone, second degree geometric nonlinearities and Coriolis effects. The equations are solved by the Galerkin method and a linear perturbation technique. Accuracy of the present method is verified by comparisons of predicted frequencies and steady state deflections with those from MSC/NASTRAN and from experiments. Parametric results are generated to establish where inclusion of only the second degree geometric nonlinearities is adequate. The nonlinear terms causing torsional divergence in thin blades are identified. The effects of Coriolis terms and several other structurally nonlinear terms are studied, and their relative importance is examined.
NASA Technical Reports Server (NTRS)
Subrahmanyam, K. B.; Kaza, K. R. V.; Brown, G. V.; Lawrence, C.
1987-01-01
The coupled bending-bending-torsional equations of dynamic motion of rotating, linearly pretwisted blades are derived including large precone, second degree geometric nonlinearities and Coriolis effects. The equations are solved by the Galerkin method and a linear perturbation technique. Accuracy of the present method is verified by conparisons of predicted frequencies and steady state deflections with those from MSC/NASTRAN and from experiments. Parametric results are generated to establish where inclusion of only the second degree geometric nonlinearities is adequate. The nonlinear terms causing torsional divergence in thin blades are identified. The effects of Coriolis terms and several other structurally nonlinear terms are studied, and their relative importance is examined.
A Coriolis force in an inertial frame
NASA Astrophysics Data System (ADS)
Kirillov, Oleg; Levi, Mark
2017-03-01
Particles in rotating saddle potentials exhibit precessional motion which, up to now, has been explained by explicit computation. We show that this precession is due to a hidden Coriolis-like force which, unlike the standard Coriolis force, is present in the inertial frame. We do so by finding a hodograph-like ‘guiding center’ transformation using the method of normal form. We also point out that the transformation cannot be of contact type in principle, thus showing that the standard (in applied literature) heuristic averaging obscures the fact that the transformation of the position must involve the velocity.
Session on coupled atmospheric/chemistry coupled models
NASA Technical Reports Server (NTRS)
Thompson, Anne
1993-01-01
The session on coupled atmospheric/chemistry coupled models is reviewed. Current model limitations, current issues and critical unknowns, and modeling activity are addressed. Specific recommendations and experimental strategies on the following are given: multiscale surface layer - planetary boundary layer - chemical flux measurements; Eulerian budget study; and Langrangian experiment. Nonprecipitating cloud studies, organized convective systems, and aerosols - heterogenous chemistry are also discussed.
Coriolis-induced cutaneous blood flow increase in the forearm and calf.
Cheung, B; Hofer, K
2001-04-01
Using venous occlusion plethysmography, Sunahara et al. reported that Coriolis-induced nausea was accompanied by an increase in forearm blood flow, suggesting a decrease in sympathetic activity to this vascular bed. No significant blood pressure and heart rate changes were observed. Vasodilation of the limbs theoretically impairs orthostatic tolerance, particularly if blood flow is shown to increase simultaneously in the lower limbs. This study examined the latter possibility. Seventeen subjects were exposed to the Coriolis cross-coupling effects induced by 20 RPM yaw rotation, and a simultaneous 45 degrees pitch forward head movement in the sagittal plane every 12 s. Forearm and calf skin blood flow were monitored in real-time using laser Doppler flowmetry (PeriFlux 4001). Our results indicated a significant (p < 0.001) simultaneous forearm and calf skin blood flow increase as a result of Coriolis cross-coupling across all 15 susceptible subjects. No significant changes in blood pressure and heart rate were observed. Coriolis-induced cardiovascular changes may confound previous reports on reduced G tolerance using ground-based centrifuges that invariably evoke cross-coupling effects.
The Challenges to Coupling Dynamic Geospatial Models
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.
Angular velocities, angular accelerations, and coriolis accelerations
NASA Technical Reports Server (NTRS)
Graybiel, A.
1975-01-01
Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.
Coriolis effects on fingering patterns under rotation.
Alvarez-Lacalle, Enrique; Gadêlha, Hermes; Miranda, José A
2008-08-01
The development of immiscible viscous fingering patterns in a rotating Hele-Shaw cell is investigated. We focus on understanding how the time evolution and the resulting morphologies are affected by the action of the Coriolis force. The problem is approached analytically and numerically by employing a vortex sheet formalism. The vortex sheet strength and a linear dispersion relation are derived analytically, revealing that the most relevant Coriolis force contribution comes from the normal component of the averaged interfacial velocity. It is shown that this normal velocity, uniquely due to the presence of the Coriolis force, is responsible for the complex-valued nature of the linear dispersion relation making the linear phases vary with time. Fully nonlinear stages are studied through intensive numerical simulations. A suggestive interplay between inertial and viscous effects is found, which modifies the dynamics, leading to different pattern-forming structures. The inertial Coriolis contribution plays a characteristic role: it generates a phase drift by deviating the fingers in the sense opposite to the actual rotation of the cell. However, the direction and intensity of finger bending is predominantly determined by viscous effects, being sensitive to changes in the magnitude and sign of the viscosity contrast. The finger competition behavior at advanced time stages is also discussed.
Angular velocities, angular accelerations, and coriolis accelerations
NASA Technical Reports Server (NTRS)
Graybiel, A.
1975-01-01
Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.
The effectiveness of Coriolis dampening of convection during aircraft high-g arcs
NASA Technical Reports Server (NTRS)
Curreri, Peter A.
1992-01-01
Directional solidification data for metal samples in KC-135 parabolic maneuvers are examined to determine evidence for Coriolis dampening of convection. Microstructural and materials properties data are examined for iron carbon, immiscible, and superalloy systems. By comparison of low-g data and high-g data with those of one-g control samples, it is determined that there is no evidence that Coriolis dampening of convective flow is effective during the 1.8 g KC-135 high-g maneuvers. A first approximation model for the high-g arc is proposed. The model yields a centrifugal radius of 20,480 ft and an angular speed of 0.397 RPM. Comparison to centrifugal solidification experiments (for an equal acceleration) where Coriolis melt growth stabilization is significant indicates that the KC-135 high-g arc is less effective in dampening convection by a factor of 100. This large difference in Coriolis dampening of convection might be taken advantage of for experiments where separation of centrifugal acceeration and Coriolis acceleration is desirable.
Dynamically Consistent Shallow-Atmosphere Equations with a Complete Coriolis force
NASA Astrophysics Data System (ADS)
Tort, Marine; Dubos, Thomas; Bouchut, François; Zeitlin, Vladimir
2014-05-01
Dynamically Consistent Shallow-Atmosphere Equations with a Complete Coriolis force Marine Tort1, Thomas Dubos1, François Bouchut2 & Vladimir Zeitlin1,3 1 Laboratoire of Dynamical Meteorology, Univ. P. and M. Curie, Ecole Normale Supérieure, and Ecole Polytechnique, FRANCE 2 Université Paris-Est, Laboratoire d'Analyse et de Mathématiques Appliquées, FRANCE 3 Institut Universitaire de France Atmospheric and oceanic motion are usually modeled within the shallow-fluid approximation, which simplifies the 3D spherical geometry. For dynamical consistency, i.e. to ensure conservation laws for potential vorticity, energy and angular momentum, the horizontal component of the Coriolis force is neglected. Here new equation sets combining consistently a simplified shallow-fluid geometry with a complete Coriolis force is presented. The derivation invokes Hamilton's principle of least action with an approximate Lagrangian capturing the small increase with height of the solid-body entrainment velocity due to planetary rotation. A three-dimensional compressible model and a one-layer shallow-water model are obtained. The latter extends previous work done on the f-plane and β-plane. Preliminary numerical results confirm the accuracy of the 3D model within the range of parameters for which the equations are relevant. These new models could be useful to incorporate a full Coriolis force into existing numerical models and to disentangle the effects of the shallow-atmosphere approximation from those of the traditional approximation. Related papers: Tort M., Dubos T., Bouchut F. and Zeitlin V. Consistent shallow-water equations on the rotating sphere with complete Coriolis force and topography. J. Fluid Mech. (under revisions) Tort M. and Dubos T. Dynamically consistent shallow-atmosphere equations with a complete Coriolis force. Q.J.R. Meteorol. Soc. (DOI: 10.1002/qj.2274)
Chen, Ziqiu; van Wijngaarden, Jennifer
2012-09-27
Rotationally resolved vibrational spectra of the four-membered heterocycle 3-oxetanone (c-C(3)H(4)O(2)) have been investigated in the 360-720 cm(-1) region with a resolution of 0.000 959 cm(-1) using synchrotron radiation from the Canadian Light Source. The observed bands correspond to motions best described as C═O deformation out-of-plane (ν(20)) at 399.6 cm(-1), C═O deformation in-plane (ν(16)) at 448.2 cm(-1), and the ring deformation (ν(7)) at 685.0 cm(-1). Infrared ground state combination differences along with previously reported pure rotational transitions were used to obtain the ground state spectroscopic parameters. Band centers, rotational and centrifugal distortion constants for the ν(7), ν(16), and ν(20) vibrational excited states were accurately determined by fitting a total of 10,319 assigned rovibrational transitions in a global analysis. The two adjacent carbonyl deformation bands, ν(16) and ν(20), were found to be mutually perturbed through a first-order a-type Coriolis interaction which was accounted for in the multiband analysis. The band centers agree within 3% of the ab initio estimates using DFT theory.
Coupled transport in rotor models
NASA Astrophysics Data System (ADS)
Iubini, S.; Lepri, S.; Livi, R.; Politi, A.
2016-08-01
Steady nonequilibrium states are investigated in a one-dimensional setup in the presence of two thermodynamic currents. Two paradigmatic nonlinear oscillators models are investigated: an XY chain and the discrete nonlinear Schrödinger equation. Their distinctive feature is that the relevant variable is an angle in both cases. We point out the importance of clearly distinguishing between energy and heat flux. In fact, even in the presence of a vanishing Seebeck coefficient, a coupling between (angular) momentum and energy arises, mediated by the unavoidable presence of a coherent energy flux. Such a contribution is the result of the ‘advection’ induced by the position-dependent angular velocity. As a result, in the XY model, the knowledge of the two diagonal elements of the Onsager matrix suffices to reconstruct its transport properties. The analysis of the nonequilibrium steady states finally allows to strengthen the connection between the two models.
Gas measurement using Coriolis mass flowmeters
Pawlas, G.; Patten, T.
1995-12-31
This paper demonstrates Coriolis mass flowmeters (CMF) can provide a solution for measuring the mass flowrate of gases directly, i.e. no knowledge of the gas properties is required. The test results for natural gas and compressed air presented here were obtained using a standard factory water calibration. This demonstrates properly designed CMF and linear devices and can provide accurate results independent of gas composition over wide pressure and mass flowrate ranges.
Use of Coriolis meters in gas applications
Patten, T.; Pawlas, G.
1995-12-31
Coriolis mass flowmeters provide a solution for measuring the mass flow rate of gases directly. Recent calibration data on compressed air shows that the factory water calibration is also valid on air. In addition, a Coriolis meter is fundamentally linear resulting in an accurate measurement over a wide flow range. Data are presented based on testing performed on Micro Motion 25 mm, 50 mm, and 75 mm Coriolis mass flowmeters on compressed air. Test pressures ranging between 1.7 bar (25 psia) and 100 bar (1450 psia) and mass flow rates ranging between 100:1 to 10:1, depending on the meter size. All calibration points fell with {plus_minus}2%, with a significant portion of the data within {plus_minus}5%. Data are also presented for a 6 mm meter on natural gas at 100 bar; all data are within {plus_minus}0.5%. Repeatability data are presented for a 9 mm meter calibrated on 100 bar air for calibration run times between 10 and 60 seconds. Meter repeatability improved approximately 10 times to {plus_minus}0.15% when the calibration time was 60 seconds.
NASA Technical Reports Server (NTRS)
Subrahmanyam, K. B.; Kaza, K. R. V.
1985-01-01
The effects of pretwist, precone, setting angle, Coriolis forces and second degree geometric nonlinearities on the natural frequencies, steady state deflections and mode shapes of rotating, torsionally rigid, cantilevered beams were studied. The governing coupled equations of flap lag extensional motion are derived including the effects of large precone and retaining geometric nonlinearities up to second degree. The Galerkin method, with nonrotating normal modes, is used for the solution of both steady state nonlinear equations and linear perturbation equations. Parametric indicating the individual and collective effects of pretwist, precone, Coriolis forces and second degree geometric nonlinearities on the steady state deflection, natural frequencies and mode shapes of rotating blades are presented. It is indicated that the second degree geometric nonlinear terms, which vanish for zero precone, can produce frequency changes of engineering significance. Further confirmation of the validity of including those generated by MSC NASTRAN. It is indicated that the linear and nonlinear Coriolis effects must be included in analyzing thick blades. The Coriolis effects are significant on the first flatwise and the first edgewise modes.
Coupled assimilation for an intermediated coupled ENSO prediction model
NASA Astrophysics Data System (ADS)
Zheng, Fei; Zhu, Jiang
2010-10-01
The value of coupled assimilation is discussed using an intermediate coupled model in which the wind stress is the only atmospheric state which is slavery to model sea surface temperature (SST). In the coupled assimilation analysis, based on the coupled wind-ocean state covariance calculated from the coupled state ensemble, the ocean state is adjusted by assimilating wind data using the ensemble Kalman filter. As revealed by a series of assimilation experiments using simulated observations, the coupled assimilation of wind observations yields better results than the assimilation of SST observations. Specifically, the coupled assimilation of wind observations can help to improve the accuracy of the surface and subsurface currents because the correlation between the wind and ocean currents is stronger than that between SST and ocean currents in the equatorial Pacific. Thus, the coupled assimilation of wind data can decrease the initial condition errors in the surface/subsurface currents that can significantly contribute to SST forecast errors. The value of the coupled assimilation of wind observations is further demonstrated by comparing the prediction skills of three 12-year (1997-2008) hindcast experiments initialized by the ocean-only assimilation scheme that assimilates SST observations, the coupled assimilation scheme that assimilates wind observations, and a nudging scheme that nudges the observed wind stress data, respectively. The prediction skills of two assimilation schemes are significantly better than those of the nudging scheme. The prediction skills of assimilating wind observations are better than assimilating SST observations. Assimilating wind observations for the 2007/2008 La Niña event triggers better predictions, while assimilating SST observations fails to provide an early warning for that event.
Nowak, Dennis A; Hermsdörfer, Joachim; Schneider, Erich; Glasauer, Stefan
2004-07-01
Grip force adaptation to Coriolis and centrifugal force perturbations was tested in healthy subjects. Eight subjects were seated in a rotating chamber in a rotating axis position. They each grasped an instrumented object resting on the thumb, which was stabilized by the other fingers from above. Subjects performed horizontal point-to-point movements with the grasped object away and towards the trunk. These movements were directed in a nonparallel fashion towards the axis of rotation prior (40 pre-rotational movements), during (80 per-rotational movements) and following (40 post-rotational movements) clockwise body rotation. During pre- and post-rotational movements two load force peaks of similar magnitude occurred during the acceleratory and deceleratory phases of the movements. Accordingly, a Coriolis force, which was orthogonal and proportional to the linear velocity of the moving arm, as well as a centrifugal force proportional to the system's squared angular velocity and movement amplitude developed during per-rotational movements. The load perturbations altered the load force profile in a characteristic way. The first 10 per-rotational movement sequence revealed that there was a less precise coupling between grip and load force magnitudes and a reduced temporo-spatial co-ordination between grip and load force profiles. With increasing number of per-rotational movements, there was significant improvement in the temporo-spatial co-ordination and in the coupling in force magnitude between grip and load force profiles, indicating an ongoing adaptation process. The coupling between grip and load forces proved to be similarly precise for the last 10 per-rotational movements and for pre-rotational movements, suggesting complete adaptation. Significant effects were observed for the first post rotational movements following adaptation to the per-rotational load characteristics both for the temporal co-ordination between grip and load forces and for the coupling in
A multilingual programming model for coupled systems.
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.
Coupling of Wave and Circulation Models in the Atlantic European North-West Shelf Predicting System
NASA Astrophysics Data System (ADS)
Staneva, Joanna; Krüger, Oliver; Behrens, Arno; Lewis, Huw; Castillo, Juan M.
2017-04-01
This study addresses the coupling between wind wave and circulation models on the example of the Atlantic - European North-West Shelf (NWS). This topic reflects the increased interest in operational oceanography to reduce prediction errors of state estimates at coastal scales. The uncertainties in most of the presently used models result from the nonlinear feedback between strong tidal currents and wind-waves, which can no longer be ignored, in particular in the coastal zone where its role seems to be dominant. Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on thermohaline distribution and ocean circulation at the NWS. Four scenarios - including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination of the three wave-induced forcing were performed to study the role of the wave-induced processes on model simulations. The individual and collective role of those processes is quantified and the results are compared with the NWS circulation model results without wave effects as well as against various in-situ measurements. The performance of the forecasting system is illustrated for the cases of several extreme events. The improved skills resulting from the new developments in the forecasting system, in particular during extreme events, justify further enhancements of the coastal operational systems. The study is performed in the frame of the COPERNICUS CMEMS Service Evolution Projects Wave2NEMO and OWAIRS.
Coriolis effect and spin Hall effect of light in an inhomogeneous chiral medium.
Zhang, Yongliang; Shi, Lina; Xie, Changqing
2016-07-01
We theoretically investigate the spin Hall effect of spinning light in an inhomogeneous chiral medium. The Hamiltonian equations of the photon are analytically obtained within eikonal approximation in the noninertial orthogonal frame. Besides the usual spin curvature coupling, the chiral parameter enters the Hamiltonian as a spin-torsion-like interaction. We reveal that both terms have parallel geometric origins as the Coriolis terms of Maxwell's equations in nontrivial frames.
Rotating black holes and Coriolis effect
NASA Astrophysics Data System (ADS)
Chou, Chia-Jui; Wu, Xiaoning; Yang, Yi; Yuan, Pei-Hung
2016-10-01
In this work, we consider the fluid/gravity correspondence for general rotating black holes. By using the suitable boundary condition in near horizon limit, we study the correspondence between gravitational perturbation and fluid equation. We find that the dual fluid equation for rotating black holes contains a Coriolis force term, which is closely related to the angular velocity of the black hole horizon. This can be seen as a dual effect for the frame-dragging effect of rotating black hole under the holographic picture.
Circuit Model for Capacitive Coupling in Inductively Coupled Plasmas
NASA Astrophysics Data System (ADS)
Watanabe, M.; Shaw, D. M.; Collins, G. J.; Sugai, H.
1998-10-01
A crude circuit model has been developed to illustrate and account for capacitive coupling between the rf coil and the bulk plasma in a stove top inductively coupled plasma source. The circuit model is composed of three levels of capacitance: the dielectric window capacitance, sheath capacitance contiguous to the dielectric window, and the chamber to ground sheath capacitance. The model is verified by quantitative comparison with the measured rf plasma potential in the bulk plasma body, plasma feedstock gas (argon) pressures below 2 mTorr. At higher pressures above 5 mTorr, the measured results diverge from the circuit model due to the transition from a spatially uniform electron density throughout the bulk plasma at pressures less than 2 mTorr to a less spatially uniform electron density at pressures above 5 mTorr.
Influence of Coriolis forces on the structure and evolution of wind-turbine wakes
NASA Astrophysics Data System (ADS)
Abkar, Mahdi; Porté-Agel, Fernando
2015-11-01
In this study, large-eddy simulation (LES) is combined with a turbine model to investigate the effect of Coriolis forces on the structure and evolution of wind-turbine wakes. In order to isolate the Coriolis effect on the turbulent wake flow, two set of simulations are performed. In the first set of simulations, atmospheric boundary layer (ABL) flow is driven by the geostrophic forces including the effect of Earth's rotation, while in the second case, the ABL flow is driven by a unidirectional pressure gradient forcing. Both cases have the same mean horizontal velocity and turbulence intensity at the hub height. The simulation results show that the Coriolis forces significantly affect the spatial distribution of the mean velocity deficit and turbulence statistics in the wake region. In particular, it is found that the Coriolis effect, responsible for vertical wind veer, has important lateral wake stretching effects, which in turn significantly impacts the wake recovery and wake meandering characteristics downwind of the turbines. We also apply the proper orthogonal decomposition (POD) to LES data of the wake. The results indicate a very high correlation between the most energetic modes and both maximum velocity deficit and wake meandering characteristics.
Influence of the Coriolis force on the structure and evolution of wind turbine wakes
NASA Astrophysics Data System (ADS)
Abkar, Mahdi; Porté-Agel, Fernando
2016-10-01
In this study, large-eddy simulation combined with a turbine model is used to investigate the effect of vertical wind veer associated with the Coriolis force on the structure and evolution of wind turbine wakes. In order to isolate the Coriolis effect on the wake, two cases are considered. In the first case, atmospheric boundary-layer flow is driven by a geostrophic wind, including the effect of Earth's rotation and the Coriolis force. In the second case, the boundary-layer flow is unidirectional and is forced by an imposed pressure gradient. Both cases have the same mean horizontal velocity and turbulence intensity at the hub height. The simulation results show that the Coriolis force significantly affects the aerodynamics of the wake including the mean velocity deficit, turbulence statistics, and wake-meandering characteristics downwind of the turbine. In particular, when the flow is forced by a geostrophic wind, vertical wind veer causes a skewed spatial structure in the wake. Moreover, the presence of lateral wind shear, in addition to the vertical one, enhances the shear production of turbulent kinetic energy and the turbulent momentum flux. This leads to a larger flow entrainment and, thus, a faster wake recovery compared to the case forced by unidirectional pressure gradient. Consistent with this result, wake meandering is also stronger in both lateral and vertical directions in the case of geostrophic forcing compared to the case with pressure-gradient forcing.
Convectively coupled Kelvin waves in CMIP5 coupled climate models
NASA Astrophysics Data System (ADS)
Wang, Lu; Li, Tim
2017-02-01
This study provided a quantitative evaluation of convectively coupled Kelvin waves (CCKWs) over the Indian Ocean and the Pacific Ocean simulated by 20 coupled climate models that participated in Coupled Model Intercomparison Project phase 5. The two leading empirical orthogonal function (EOF) modes of filtered daily precipitation anomalies are used to represent the eastward propagating CCKWs in both observations and simulations. The eigenvectors and eigenvalues of the EOF modes represent the spatial patterns and intensity of CCKWs respectively, and the lead-lag relationship between the two EOF principle components describe the phase propagation of CCKWs. A non-dimensional metric was designed in consideration of all the three factors (i.e., pattern, amplitude and phase propagation) for evaluation. The relative rankings of the models based on the skill scores calculated by the metric are conducted for the Indian Ocean and the Pacific Ocean, respectively. Two models (NorESM1-M and MPI-ESM-LR) are ranked among the best 20 % for both the regions. Three models (inmcm4, MRI-CGCM3 and HadGEM2-ES) are ranked among the worst 20 % for both the regions. While the observed CCKW amplitude is greater north of the equator in the Pacific, some models overestimate the CCKW ampliutde in the Southern Hemisphere. This bias is related to the mean state precipitation bias along the south Pacific convergence zone.
Coriolis effects enhance lift on revolving wings.
Jardin, T; David, L
2015-03-01
At high angles of attack, an aircraft wing stalls. This dreaded event is characterized by the development of a leading edge vortex on the upper surface of the wing, followed by its shedding which causes a drastic drop in the aerodynamic lift. At similar angles of attack, the leading edge vortex on an insect wing or an autorotating seed membrane remains robustly attached, ensuring high sustained lift. What are the mechanisms responsible for both leading edge vortex attachment and high lift generation on revolving wings? We review the three main hypotheses that attempt to explain this specificity and, using direct numerical simulations of the Navier-Stokes equations, we show that the latter originates in Coriolis effects.
Fluid Coupling in a Discrete Cochlear Model
NASA Astrophysics Data System (ADS)
Elliott, S. J.; Lineton, B.; Ni, G.
2011-11-01
The interaction between the basilar membrane, BM, dynamics and the fluid coupling in the cochlea can be formulated using a discrete model by assuming that the BM is divided into a number of longitudinal elements. The form of the fluid coupling can then be understood by dividing it into a far field component, due to plane wave acoustic coupling, and a near field component, due to higher order evanescent acoustic modes. The effects of non-uniformity and asymmetry in the cross-sectional areas of the fluid chambers can also be accounted for within this formulation. The discrete model is used to calculate the effect on the coupled BM response of a short cochlear implant, which reduces the volume of one of the fluid chambers over about half its length. The passive response of the coupled cochlea at lower frequencies is shown to be almost unaffected by this change in volume.
NASA Astrophysics Data System (ADS)
Defazio, Paolo; Gamallo, Pablo; Petrongolo, Carlo
2012-02-01
We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O(1D) + N2( {X{}^1Σ _g^ + } ) toO(3P) + N2( {X{}^1Σ _g^ + } ) on the N2O tilde X{}^1A^' }, tilde a{}^3A^'', and tilde b{}^3A^' } coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initial-state-resolved probabilities and cross sections σ _{j_0 } for the ground vibrational and the first two rotational states of N2, j0 = 0 and 1. Labeling symmetry angular states by j and K, we report selection rules for j and for the minimum K value associated with any electronic state, showing that tilde a{}^3A^'' is uncoupled in the centrifugal-sudden (CS) approximation at j0 = 0. The dynamics is resonance-dominated, the probabilities are larger at low K, σ _{j_0 } decrease with the collision energy and increase with j0, and the CS σ0 is lower than the CC one. The nonadiabatic interactions play different roles on the quenching dynamics, because the tilde X{}^1A^ ' } - tilde b{}^3A^ ' } SO effects are those most important while the tilde a{}^3A^'' - tilde b{}^3A ^' } RT ones are negligible.
Defazio, Paolo; Gamallo, Pablo; Petrongolo, Carlo
2012-02-07
We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O((1)D) + N(2)(X(1)Σ(g)(+)) → O((3)P) + N(2)(X(1)Σ(g)(+)) on the N(2)O X(1)A', ã(3)A", and b(3)A' coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initial-state-resolved probabilities and cross sections σ(j(0)) for the ground vibrational and the first two rotational states of N(2), j(0) = 0 and 1. Labeling symmetry angular states by j and K, we report selection rules for j and for the minimum K value associated with any electronic state, showing that ã(3)A" is uncoupled in the centrifugal-sudden (CS) approximation at j(0) = 0. The dynamics is resonance-dominated, the probabilities are larger at low K, σ(j(0)) decrease with the collision energy and increase with j(0), and the CS σ(0) is lower than the CC one. The nonadiabatic interactions play different roles on the quenching dynamics, because the X(1)A'-b(3)A' SO effects are those most important while the ã(3)A"-b(3)A' RT ones are negligible.
Higgs couplings in noncommutative Standard Model
NASA Astrophysics Data System (ADS)
Batebi, S.; Haghighat, M.; Tizchang, S.; Akafzade, H.
2015-06-01
We consider the Higgs and Yukawa parts of the Noncommutative Standard Model (NCSM). We explore the NC-action to give all Feynman rules for couplings of the Higgs boson to electroweak gauge fields and fermions.
Dynamic coupling of three hydrodynamic models
NASA Astrophysics Data System (ADS)
Hartnack, J. N.; Philip, G. T.; Rungoe, M.; Smith, G.; Johann, G.; Larsen, O.; Gregersen, J.; Butts, M. B.
2008-12-01
The need for integrated modelling is evidently present within the field of flood management and flood forecasting. Engineers, modellers and managers are faced with flood problems which transcend the classical hydrodynamic fields of urban, river and coastal flooding. Historically the modeller has been faced with having to select one hydrodynamic model to cover all the aspects of the potentially complex dynamics occurring in a flooding situation. Such a single hydrodynamic model does not cover all dynamics of flood modelling equally well. Thus the ideal choice may in fact be a combination of models. Models combining two numerical/hydrodynamic models are becoming more standard, typically these models combine a 1D river model with a 2D overland flow model or alternatively a 1D sewer/collection system model with a 2D overland solver. In complex coastal/urban areas the flood dynamics may include rivers/streams, collection/storm water systems along with the overland flow. The dynamics within all three areas is of the same time scale and there is feedback in the system across the couplings. These two aspects dictate a fully dynamic three way coupling as opposed to running the models sequentially. It will be shown that the main challenges of the three way coupling are time step issues related to the difference in numerical schemes used in the three model components and numerical instabilities caused by the linking of the model components. MIKE FLOOD combines the models MIKE 11, MIKE 21 and MOUSE into one modelling framework which makes it possible to couple any combination of river, urban and overland flow fully dynamically. The MIKE FLOOD framework will be presented with an overview of the coupling possibilities. The flood modelling concept will be illustrated through real life cases in Australia and in Germany. The real life cases reflect dynamics and interactions across all three model components which are not possible to reproduce using a two-way coupling alone. The
NASA Astrophysics Data System (ADS)
Ashkenazy, Yosef
2017-03-01
There are two main comparable sources of energy to the deep ocean-winds and tides. However, the identity of the most efficient mechanism that transfers wind energy to the deep ocean is still debated. Here we study, using oceanic general circulation model simulations and analytic derivations, the way that the wind directly supplies energy down to the bottom of the ocean when it is stochastic and temporally correlated or when it is periodic with a frequency that matches the Coriolis frequency. Basically, under these, commonly observed, conditions, one of the wind components resonates with the Coriolis frequency. Using reanalysis surface wind data and our simple model, we show that about one-third of the kinetic energy that is associated with wind-induced currents resides in the abyssal ocean, highlighting the importance of the resonance of the wind with the Coriolis force.
The menstrual cycle and susceptibility to coriolis-induced sickness.
Cheung, B; Heskin, R; Hofer, K; Gagnon, M
2001-01-01
Survey studies on motion sickness susceptibility suggest that females tend to report greater severity in illness and higher incidence of vomiting than males. Menstruation is said to be a contributing factor. A recent study suggested that females were least susceptible to seasickness during ovulation in a "round the world" yacht race. Sixteen subjects (18-36 years old) were exposed to Coriolis cross-coupling stimulation in the laboratory. They were tested once during permenstruation (Day 1-5), ovulation (Day 12-15) and premenstruation (Day 24-28), based on a normalized 28-day cycle, in a randomised design. Physiological measurements of motion sickness included forearm and calf cutaneous blood flow. Subjective evaluation of sickness symptoms was based on Graybiel's diagnostic criteria and Golding's rating method. Our results indicated that under controlled laboratory conditions, different phases of the menstrual cycle appear to have no influence on subjective symptoms of motion sickness or on cutaneous blood flow increase in the forearm and calf. The lack of commonality between the types and levels of hormones that are released during motion sickness and those that are involved in different menstrual phases appears to support our findings.
Changes in visual function during the Coriolis illusion.
Horng, Chi-Ting; Liu, Chung-Cheng; Kuo, Daih-Iluang; Shieh, Po-Chuen; Wu, Yi-Chang; Chen, Jiann-Torng; Tsai, Ming-Ling
2009-04-01
The Coriolis illusion produces spatial disorientation and is, therefore, dangerous for pilots. It is not known whether it also affects visual function (visual acuity and stereopsis). There were 18 subjects (15 men and 3 women, mean age 24.7 yr) enrolled in the study. A spatial disorientation simulator was used to produce Coriolis stimulation. The visual acuity of the subjects was evaluated with the Rosenbaum Vision Card before and during Coriolis stimulation. Stereopsis was measured with the Titmus stereo test. Throughout the experiments, eyeball movements were observed on a television monitor. Electrooculography (EOG) and electroencephalography (EEG) were also documented. Before Coriolis stimulation, the visual acuity and stereopsis of all subjects were 20/20 and 40 s of arc, respectively. During the Coriolis illusion, the visual acuity of nine subjects (50%) remained 20/20, whereas the visual acuity of the others (50%) dropped by two lines. The stereopsis of most subjects (77.8%) decreased to 800 arc-seconds or less. Rhythmic nystagmus was observed, while EOG amplitudes were significantly elevated compared with those at baseline (9.41 +/- 0.26 microv2 and 8.45 +/- 0.36 microv2, respectively). EEG activity (frequency) was also greater than at baseline (13.15 +/- 0.84 Hz and 11.94 +/- 1.20 Hz, respectively; P < 0.05). During Coriolis stimulation, the visual acuity of the subjects remained stable, but their stereopsis was reduced. Further study is warranted.
Some questions on the Coriolis force, the structure of rotational states and the IBM
Khoo, T.L.
1980-01-01
Participants in the Round Table Discussion at the International Conference on Band Structure and Nuclear Dynamics were to make editorial comments on what transpired during the conference. This paper contains comments of one panel member on questions which he feels were not addressed during the meeting. His comments concern the Coriolis force in rotating nuclei and its relation to the nucleon-nucleon interaction, the microscopic origin of rotational states, and the interacting boson model. (RWR)
Dual coupling effective band model for polarons
NASA Astrophysics Data System (ADS)
Marchand, Dominic J. J.; Stamp, Philip C. E.; Berciu, Mona
2017-01-01
Nondiagonal couplings to a bosonic bath completely change polaronic dynamics, from the usual diagonally coupled paradigm of smoothly varying properties. We study, using analytic and numerical methods, a model having both diagonal Holstein and nondiagonal Su-Schrieffer-Heeger (SSH) couplings. The critical coupling found previously in the pure SSH model, at which the k =0 effective mass diverges, now becomes a transition line in the coupling constant plane—the form of the line depends on the adiabaticity parameter. Detailed results are given for the quasiparticle and ground-state properties, over a wide range of couplings and adiabaticity ratios. The new paradigm involves a destabilization, at the transition line, of the simple Holstein polaron to one with a finite ground-state momentum, but with everywhere a continuously evolving band shape. No "self-trapping transition" exists in any of these models. The physics may be understood entirely in terms of competition between different hopping terms in a simple renormalized effective band theory. The possibility of further transitions is suggested by the results.
An Appraisal of Coupled Climate Model Simulations
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.''
The role of the complete Coriolis force in weakly stratified oceanic flows
NASA Astrophysics Data System (ADS)
Tort, M.; Winters, K. B.; Ribstein, B.; Zeitlin, V.
2016-02-01
Ocean dynamics is usually described using the primitive equations based on the so-called traditional approximation (TA), where the Coriolis force associated with the horizontal component of the planetary rotation is neglected (also called non-traditional (NT) part proportional to cosΦ, see Fig 1.). However, recent studies have shown that the NT part of the Coriolis force plays a non-negligible dynamical role in some particular oceanic flows (see Gerkema et al., 2008 for an extensive review of NT effects for geophysical and astrophysical flows). Here we explore the relevance of including the NT component of the Coriolis force in ocean models, by presenting particular results regarding two different mid-latitude flow configurations after relaxing the TA: Propagation of wind-induced near-inertial waves (NIWs). Under the TA, NIWs propagate toward the equator, the inertially poleward propagation being internally reflected at a depth-independent critical latitude. The combined effects of the NT Coriolis force and weak stratification in the deep ocean leads to the existence of waveguides for sub-inertial waves, which get trapped and propagate further poleward (Winters et al., 2011). Here we consider storm-induced NIWs and their evolution in a non-linear Boussinesq model on the β-plane in the NT approximation. Preliminary results are presented concerning the behavior of the waves in a weakly stratified mixed-layer, where NT effects are expected to be significant. Inertial instability. A detailed linear stability analysis of the Bickley jet at large Rossby numbers in the NT approximation on the f-plane is performed for long waves in a continuously stratified Boussinesq model. For a sufficiently weak stratification, both symmetric and asymmetric inertial instabilities have substantially higher growth rates than in the TA while no discernible differences between the two approximations are observed for strong enough stratifications (Tort et al., 2015).
Thermocapillary-Coriolis Instabilities in Liquid Bridges
NASA Astrophysics Data System (ADS)
Zebib, A.; Le Cunff, C.
1997-11-01
Coriolis effects on thermocapillary instabilities in a liquid bridge of infinite length(J.-J. Xu & S. H. Davis, Phys. of Fluids 27, 1102-1107 (1983)) are investigated. The flow is driven by an imposed temperature gradient along the z-direction in a (r,θ,z) rotating frame of reference. When the rotation vector is parallel to the z-axis the base return flow with no rotation is not modified. In this case, rotation is stabilizing with traveling waves preferred. If the rotation is orthogonal to the z-axis, the base flow is modified and is no longer one-dimensional. Asymptotic methods valid for small rotation are used to calculate the base flow which may become multicellular, both in the radial and azimuthal directions, depending on the Prandtl, Marangoni, and Biot numbers. Linear stability analysis of the new base flow indicates that this type of rotation can be destabilizing while traveling azimuthal waves continue to be the prefered form of convection.
Observation of the nu(6) + nu(9) Band of Ketene via Resonant Coriolis Interaction with nu(8).
Gruebele; Johns; Nemes
1999-12-01
We observed and analyzed a b-axis Coriolis resonance between higher J states of the nu(6) + nu(9) combination band and the nu(8) fundamental of ketene in the spectral region 940-970 cm(-1). The interaction resonantly couples K(a) = 1 states of the combination band to K(a) = 0 states of the fundamental and also affects K(a) = 1, 2 states in the fundamental. Due to the involvement of strongly asymmetry-split low K levels, the rotational constants and band origin of nu(6) + nu(9) could be accurately determined and are discussed in the light of high-quality anharmonic force fields. The Coriolis coupling parameter, zeta(b)(8,6+9), is very precisely determined. A smaller perturbation, which could not be fully analyzed, is tentatively attributed to K(a) = 2 upper states in the nu(5) + nu(9) band. Copyright 1999 Academic Press.
Simplified coupling power model for fibers fusion
NASA Astrophysics Data System (ADS)
Saktioto, J.; Ali, J.; Fadhali, M.
2009-09-01
Fiber coupler fabrication used for an optical waveguide requires lossless power for an optimal application. The previous research coupled fibers were successfully fabricated by injecting hydrogen flow at 1 bar and fused slightly by unstable torch flame in the range of 800-1350°C. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of geometrical fiber affects the normalized frequency V even for single mode fibers. V is derived and some parametric variations are performed on the left and right hand side of the coupling region. A partial power is modelled and derived using V, normalized lateral phase constant u, and normalized lateral attenuation constant, w through the second kind of modified Bessel function of the l order, which obeys the normal mode and normalized propagation constant b. Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u, and w over the pulling length of 7500 µm for 1-D. The core radius of a fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding. This model has power phenomena in transmission and reflection for an optical switch and tunable filter.
Mass functions in coupled dark energy models
Mainini, Roberto; Bonometto, Silvio
2006-08-15
We evaluate the mass function of virialized halos, by using Press and Schechter (PS) and/or Steth and Tormen (ST) expressions, for cosmologies where dark energy (DE) is due to a scalar self-interacting field, coupled with dark matter (DM). We keep to coupled DE (cDE) models known to fit linear observables. To implement the PS-ST approach, we start from reviewing and extending the results of a previous work on the growth of a spherical top-hat fluctuation in cDE models, confirming their most intriguing astrophysical feature, i.e. a significant baryon-DM segregation, occurring well before the onset of any hydrodynamical effect. Accordingly, the predicted mass function depends on how halo masses are measured. For any option, however, the coupling causes a distortion of the mass function, still at z=0. Furthermore, the z-dependence of cDE mass functions is mostly displaced, in respect to {lambda}CDM, in the opposite way of uncoupled dynamical DE. This is an aspect of the basic underlying result, that even a little DM-DE coupling induces relevant modifications in the nonlinear evolution. Therefore, without causing great shifts in linear astrophysical observables, the DM-baryon segregation induced by the coupling can have an impact on a number of cosmological problems, e.g., galaxy satellite abundance, spiral disk formation, apparent baryon shortage, entropy input in clusters, etc.
Parallelization of the Coupled Earthquake Model
NASA Technical Reports Server (NTRS)
Block, Gary; Li, P. Peggy; Song, Yuhe T.
2007-01-01
This Web-based tsunami simulation system allows users to remotely run a model on JPL s supercomputers for a given undersea earthquake. At the time of this reporting, predicting tsunamis on the Internet has never happened before. This new code directly couples the earthquake model and the ocean model on parallel computers and improves simulation speed. Seismometers can only detect information from earthquakes; they cannot detect whether or not a tsunami may occur as a result of the earthquake. When earthquake-tsunami models are coupled with the improved computational speed of modern, high-performance computers and constrained by remotely sensed data, they are able to provide early warnings for those coastal regions at risk. The software is capable of testing NASA s satellite observations of tsunamis. It has been successfully tested for several historical tsunamis, has passed all alpha and beta testing, and is well documented for users.
NASA Astrophysics Data System (ADS)
Alari, Victor; Staneva, Joanna; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian; Janssen, Peter
2016-08-01
Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on water temperature distribution and heat exchange at regional scale (the Baltic Sea). Four scenarios—including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination these forcings—were simulated to test the impact of different terms on simulated temperature distribution. The scenario simulations were compared to a control simulation, which included a constant wave-breaking coefficient, but otherwise was without any wave effects. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwelling's. Overall, when all three wave effects were accounted for, did the estimates of temperature improve compared to control simulation. During the summer, the wave-induced water temperature changes were up to 1 °C. In northern parts of the Baltic Sea, a warming of the surface layer occurs in the wave included simulations in summer months. This in turn reduces the cold bias between simulated and measured data, e.g. the control simulation was too cold compared to measurements. The warming is related to sea-state dependent energy flux. This implies that a spatio-temporally varying wave-breaking coefficient is necessary, because it depends on actual sea state. Wave-induced cooling is mostly observed in near-coastal areas and is the result of intensified upwelling in the scenario, when Stokes-Coriolis forcing is accounted for. Accounting for sea-state dependent momentum flux results in modified heat exchange at the water-air boundary which consequently leads to warming of surface water compared to control simulation.
Modeling partially coupled objects with smooth particle hydrodynamics
Wingate, C.A.
1996-10-01
A very simple phenomenological model is presented to model objects that are partially coupled (i.e. welded or bonded) where usually the coupled interface is weaker than the bulk material. The model works by letting objects fully interact in compression and having the objects only partially interact in tension. A disconnect factor is provided to adjust the tensile interaction to simulate coupling strengths. Three cases of an example impact calculation are shown-no coupling, full coupling and partial coupling.
Numerical Experiments on Homogeneous Strained Turbulence Subjected to Coriolis Force
NASA Technical Reports Server (NTRS)
Shariff, K.; Blaisdell, G. A.; Abid, R.; Speziale, C. G.; Rai, Man Mohan (Technical Monitor)
1995-01-01
Homogeneous turbulent flows with various combinations of strain-rate, rotation rate and coriolis force capture some important aspects of more complex flows with streamline curvature and rotation. Presently, a situation is considered in which as a box of turbulence rotates, strain axes rotate with it. This is to be contrasted with the elliptic streamline flow in which the strain axes are fixed in an inertial frame. The elliptic flow is known to exhibit (inviscid) growth of turbulent energy and one might expect even more rapid growth with the strain-axes following the box. Instead, it is found that the sign of the Reynolds shear stress is reversed leading to a negative production term for turbulent energy. Partial understanding of the phenomenon is obtained from a consideration of the rotation of inertial waves relative to the strain axes as well as the "pressure-less" RDT argument put forward by Cambon etal. [J. Fluid Mech, 278, 175]. Some comparisons with the predictions of second-order closure models will be presented.
Coupled Disturbance Modelling And Validation Of A Reaction Wheel Model
NASA Astrophysics Data System (ADS)
Zhang, Zhe; Aglietti, Gugliemo S.
2012-07-01
Microvibrations of a RWA are usually studied in either hard-mounted or coupled conditions, although coupled wheel-structure disturbances are more representative than the hard-mounted disturbances. The coupled analysis method of the wheel-structure is not as well developed as the hard-mounted one. A coupled disturbance analysis method is proposed in this paper. One of the most important factors in coupled disturbance analysis - the accelerance or dynamic mass of the wheel is measured and results are validated with an equivalent FE model. The wheel hard-mounted disturbances are also measured from a vibration measurement platform particularly designed for this study. Wheel structural modes are solved from its analytical disturbance model and validated with the test results. The wheel-speed dependent accelerance analysis method is proposed.
Calculating intensities using effective Hamiltonians in terms of Coriolis-adapted normal modes.
Karthikeyan, S; Krishnan, Mangala Sunder; Carrington, Tucker
2005-01-15
The calculation of rovibrational transition energies and intensities is often hampered by the fact that vibrational states are strongly coupled by Coriolis terms. Because it invalidates the use of perturbation theory for the purpose of decoupling these states, the coupling makes it difficult to analyze spectra and to extract information from them. One either ignores the problem and hopes that the effect of the coupling is minimal or one is forced to diagonalize effective rovibrational matrices (rather than diagonalizing effective rotational matrices). In this paper we apply a procedure, based on a quantum mechanical canonical transformation for deriving decoupled effective rotational Hamiltonians. In previous papers we have used this technique to compute energy levels. In this paper we show that it can also be applied to determine intensities. The ideas are applied to the ethylene molecule.
Coupled wave model for large magnet coils
NASA Technical Reports Server (NTRS)
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.
Towards Better Coupling of Hydrological Simulation Models
NASA Astrophysics Data System (ADS)
Penton, D.; Stenson, M.; Leighton, B.; Bridgart, R.
2012-12-01
Standards for model interoperability and scientific workflow software provide techniques and tools for coupling hydrological simulation models. However, model builders are yet to realize the benefits of these and continue to write ad hoc implementations and scripts. Three case studies demonstrate different approaches to coupling models, the first using tight interfaces (OpenMI), the second using a scientific workflow system (Trident) and the third using a tailored execution engine (Delft Flood Early Warning System - Delft-FEWS). No approach was objectively better than any other approach. The foremost standard for coupling hydrological models is the Open Modeling Interface (OpenMI), which defines interfaces for models to interact. An implementation of the OpenMI standard involves defining interchange terms and writing a .NET/Java wrapper around the model. An execution wrapper such as OatC.GUI or Pipistrelle executes the models. The team built two OpenMI implementations for eWater Source river system models. Once built, it was easy to swap river system models. The team encountered technical challenges with versions of the .Net framework (3.5 calling 4.0) and with the performance of the execution wrappers when running daily simulations. By design, the OpenMI interfaces are general, leaving significant decisions around the semantics of the interfaces to the implementer. Increasingly, scientific workflow tools such as Kepler, Taverna and Trident are able to replace custom scripts. These tools aim to improve the provenance and reproducibility of processing tasks. In particular, Taverna and the myExperiment website have had success making many bioinformatics workflows reusable and sharable. The team constructed Trident activities for hydrological software including IQQM, REALM and eWater Source. They built an activity generator for model builders to build activities for particular river systems. The models were linked at a simulation level, without any daily time
Nonlinear Walecka models and point-coupling relativistic models
Lourenco, O.; Amaral, R. L. P. G.; Dutra, M.; Delfino, A.
2009-10-15
We study hadronic nonlinear point-coupling (NLPC) models which reproduce numerically the binding energy, the incompressibility, and the nucleon effective mass at the nuclear matter saturation obtained by different nonlinear Walecka (NLW) models. We have investigated their behaviors as functions of the nuclear matter density to observe how they deviate from known NLW models. In our study we present a meson-exchange modified nonlinear Walecka model (MNLW) which exactly underlies a nonlinear point-coupling model (NLPC) presenting third- and fourth-order scalar density self-couplings. A discussion about naive dimensional analysis (NDA) and naturalness is also provided for a large class of NLW and NLPC models. At finite temperature, critical and flash parameters of both approaches are presented.
Coupling biology and oceanography in models.
Fennel, W; Neumann, T
2001-08-01
The dynamics of marine ecosystems, i.e. the changes of observable chemical-biological quantities in space and time, are driven by biological and physical processes. Predictions of future developments of marine systems need a theoretical framework, i.e. models, solidly based on research and understanding of the different processes involved. The natural way to describe marine systems theoretically seems to be the embedding of chemical-biological models into circulation models. However, while circulation models are relatively advanced the quantitative theoretical description of chemical-biological processes lags behind. This paper discusses some of the approaches and problems in the development of consistent theories and indicates the beneficial potential of the coupling of marine biology and oceanography in models.
Four mass coupled oscillator guitar model.
Popp, John E
2012-01-01
Coupled oscillator models have been used for the low frequency response (50 to 250 Hz) of a guitar. These 2 and 3 mass models correctly predict measured resonance frequency relationships under various laboratory boundary conditions, but did not always represent the true state of a guitar in the players' hands. The model presented has improved these models in three ways, (1) a fourth oscillator includes the guitar body, (2) plate stiffnesses and other fundamental parameters were measured directly and effective areas and masses used to calculate the responses, including resonances and phases, directly, and (3) one of the three resultant resonances varies with neck and side mass and can also be modeled as a bar mode of the neck and body. The calculated and measured resonances and phases agree reasonably well.
Coupled process modeling and waste package performance
McGrail, B.P.; Engel, D.W.
1992-11-01
The interaction of borosilicate waste glasses with water has been studied extensively and reasonably good models are available that describe the reaction kinetics and solution chemical effects. Unfortunately, these models have not been utilized in performance assessment analyses, except in estimating radionuclide solubilities at the waste form surface. A geochemical model has been incorporated in the AREST code to examine the coupled processes of glass dissolution and transport within the engineering barrier system. Our calculations show that the typical assumptions used in performance assessment analyses, such as fixed solubilities or constant reaction rate at the waste form surface, do not always give conservative or realistic predictions of radionuclide release. Varying the transport properties of the waste package materials is shown to give counterintuitive effects on the release rates of some radionuclides. The use of noncoupled performance assessment models could lead a repository designer to an erroneous conclusion regarding the relative benefit of one waste package design or host rock setting over another.
Coriolis effects on nonlinear oscillations of rotating cylinders and rings
NASA Technical Reports Server (NTRS)
Padovan, J.
1976-01-01
The effects which moderately large deflections have on the frequency spectrum of rotating rings and cylinders are considered. To develop the requisite solution, a variationally constrained version of the Lindstedt-Poincare procedure is employed. Based on the solution developed, in addition to considering the effects of displacement induced nonlinearity, the role of Coriolis forces is also given special consideration.
Coupling a terrestrial biogeochemical model to the common land model
Shi, Xiaoying; Mao, Jiafu; Wang, Yingping; Dai, Yongjiu; Tang, Xuli
2011-01-01
A terrestrial biogeochemical model (CASACNP) was coupled to a land surface model (the Common Land Model, CoLM) to simulate the dynamics of carbon substrate in soil and its limitation on soil respiration. The combined model, CoLM-CASACNP, was able to predict long-term carbon sources and sinks that CoLM alone could not. The coupled model was tested using measurements of belowground respiration and surface fluxes from two forest ecosystems. The combined model simulated reasonably well the diurnal and seasonal variations of net ecosystem carbon exchange, as well as seasonal variation in the soil respiration rate of both the forest sites chosen for this study. However, the agreement between model simulations and actual measurements was poorer under dry conditions. The model should be tested against more measurements before being applied globally to investigate the feedbacks between the carbon cycle and climate change.
Fluctuations in a coupled population model
NASA Astrophysics Data System (ADS)
Jakeman, E.; Hopcraft, K. I.; Matthews, J. O.
2005-07-01
We investigate a discrete Markov process in which the immigration of individuals into one population is controlled by the fluctuations in another. We examine the effect of coupling back the second population to the first through a similar mechanism and derive exact solutions for the generating functions of the population statistics. We show that a stationary state exists over a certain parameter range and obtain expressions for moments and correlation functions in this regime. When more than two populations are coupled, cyclically transient oscillations and periodic behaviour of correlation functions are predicted. We demonstrate that if the initial distribution of either population is stable, or more generally has a power-law tail that falls off like N-(1+α) (0 < α < 1), then for certain parameter values there exists a stationary state that is also power law but not stable. This stationary state cannot be accessed from a single multiple immigrant population model, but arises solely from the nonlinear interaction of the coupled system.
Multi-scale Model Coupling for CFD Simulations of Discharge Dispersion in the Sea
NASA Astrophysics Data System (ADS)
Robinson, D.; Wood, M.; Piggott, M. D.; Gorman, G.
2014-12-01
The processes that influence the dispersion of effluent discharges in the sea occur over a wide range of length and time scales. The distance that effluent can travel before it is considered mixed can be several kilometres, whereas the turbulent eddies that affect the near-field mixing of a discharge can be as small as a few centimetres. The range of scales that are involved mean that it is not generally practical to include all influencing physical phenomena within one model. Typically, the modelling of effluent dispersion is performed using two separate numerical models: a local model of the outlet(s), including the near-field effects of momentum, buoyancy and turbulence; and a larger scale model that can include the far-field effects of tidal-, wind- and wave-driven-currents, water depth variations, atmospheric fluxes, and Coriolis forces. The boundary between the two models is often not strictly defined, but is usually placed at the transition from where the behaviour of the effluent is dominated by the ambient environment, rather than the discharge characteristics and outfall configuration. In most real applications, this transition line varies considerably in time and space. This paper presents the findings of collaborative research between the Applied Modelling and Computation Group (AMCG) at Imperial College London, UK, and HR Wallingford Ltd. Results are presented using a range of coupling methods to link the near- and far-field mixing regions. An idealised domain and tidal conditions are used, with the outfall and ambient conditions typical of those found at small coastal desalination plants. Open-source CFD code Fluidity is used for both the near-field and far-field modelling. Fluidity scales well when run in parallel on large numbers of cores. It also has an anisotropic adaptive mesh capability which allows local control over solution accuracy throughout the domain. This combination means that accuracy can be achieved without excessive time costs, with
Grand challenge scientific questions in coupled modeling
NASA Technical Reports Server (NTRS)
Koch, Steven
1993-01-01
Most convective field experiments in the past (e.g., SESAME, CCOPE, CINDE) have attempted to resolve only the immediate scales of moist convection using network arrays that spanned two or three atmospheric scales at most. Furthermore, these scales have been defined more on practical considerations (cost, manpower, etc.) than on a clear understanding of their theoretical significance. Unfortunately, this has precluded a description of the entire life cycle of MCS's and their interaction with larger scale systems, the land surface, and trace species. Fortunately, the following factors now make it possible to attempt to simulate scale contraction processes from the synoptic scale down to the cloud scale, as well as interactions between complex meteorological, land surface, precipitation, chemical, and hydrologic processes with coupled, multiscale models: the availability of new technology to sample meteorological fields at high temporal and spatial resolution over a broad region made possible by the weather observing modernization program; increased computer power and improved numerical approaches to run limited area models with nonhydrostatic precipitation physics so as to explicitly resolve MCS (Mesoscale Convective System) processes; and four dimensional assimilation of non-conventional data to provide dynamically consistent datasets for diagnostic analysis of nonlinear scale-interactive dynamics. Several examples of scale-interactive processes which present grand challenges for coupled, multiscale modeling were presented.
Modeling and characterization of multiple coupled lines
NASA Astrophysics Data System (ADS)
Tripathi, Alok
1999-10-01
A configuration-oriented circuit model for multiple coupled lines in an inhomogeneous medium is developed and presented in this thesis. This circuit model consists of a network of uncoupled transmission lines and is readily modeled with simulation tools like LIBRA© and SPICE ©. It provides an equivalent circuit representation which is simple and topologically meaningful as compared to the model based on modal decomposition. The configuration-oriented model is derived by decomposing the immittance matrices associated with an n coupled line 2n-port system. Time- and frequency- domain simulations of typical coupled line multiports are included to exemplify the utility of the model. The model is useful for the simulation and design of general single and multilayer coupled line components, such as filters and couplers, and for the investigation of signal integrity issues including crosstalk in interconnects associated with high speed digital and mixed signal electronic modules and packages. It is shown that multiconductor lossless structures in an inhomogeneous medium can be characterized by multiport time-domain reflection (MR) measurements. A synthesis technique of an equivalent lossless (non-dispersive) uniform multiconductor n coupled lines (UMCL) 2n-port system from the measured discrete time-domain reflection response is presented. This procedure is based on the decomposition of the characteristic immittance matrices of the UMCL in terms of partial mode immittance matrices. The decomposition scheme leads to the discrete transition matrix function of a UMCL 2n-port system. This in turn establishes a relationship between the normal-mode parameters of the UMCL and the measured impulse reflection and transmission response. Equivalence between the synthesis procedure presented in this thesis and the solution of a special form of an algebraic Riccati matrix equation whose solution can lead to the normal-mode parameters and a real termination network is illustrated. In
Quantum Ising model coupled with conducting electrons
NASA Astrophysics Data System (ADS)
Yamashita, Yasufumi; Yonemitsu, Kenji
2005-01-01
The effect of photo-doping on the quantum paraelectric SrTiO3 is studied by using the one-dimensional quantum Ising model, where the Ising spin describes the effective lattice polarization of an optical phonon. Two types of electron-phonon couplings are introduced through the modulation of transfer integral via lattice deformations. After the exact diagonalization and the perturbation studies, we find that photo-induced low-density carriers can drastically alter quantum fluctuations when the system locates near the quantum critical point between the quantum para- and ferro-electric phases.
Coriolis effect in optics: unified geometric phase and spin-Hall effect.
Bliokh, Konstantin Y; Gorodetski, Yuri; Kleiner, Vladimir; Hasman, Erez
2008-07-18
We examine the spin-orbit coupling effects that appear when a wave carrying intrinsic angular momentum interacts with a medium. The Berry phase is shown to be a manifestation of the Coriolis effect in a noninertial reference frame attached to the wave. In the most general case, when both the direction of propagation and the state of the wave are varied, the phase is given by a simple expression that unifies the spin redirection Berry phase and the Pancharatnam-Berry phase. The theory is supported by the experiment demonstrating the spin-orbit coupling of electromagnetic waves via a surface plasmon nanostructure. The measurements verify the unified geometric phase, demonstrated by the observed polarization-dependent shift (spin-Hall effect) of the waves.
The Coriolis Interaction between the nu(9) and nu(7) Fundamental Bands of Methylene Fluoride.
Goh; Tan; Ong; Teo
2000-06-01
The infrared spectrum of the nu(7) and nu(9) bands of methylene fluoride-d(2) (CD(2)F(2)) has been recorded with an unapodized resolution of 0.0024 cm(-1) in the frequency range of 940-1030 cm(-1) using the Fourier transform technique. A weak b-type Coriolis interaction term was found to couple these two vibrational states with band centers about 42 cm(-1) apart. By fitting a total of 1031 infrared transitions of both nu(7) and nu(9) with a standard deviation of 0.0011 cm(-1) using a Watson's A-reduced Hamiltonian in the I(r) representation with the inclusion of a b-type Coriolis resonance term, two sets of rovibrational constants for nu(7) = 1 and nu(9) = 1 states up to sextic order were derived. The nu(7) band is C type, while the nu(9) band is A type with band centers at 961.8958 +/- 0.0005 and 1003.7421 +/- 0.0001 cm(-1), respectively. Copyright 2000 Academic Press.
Coupled map lattice model of jet breakup
Minich, R W; Schwartz, A J; Baker, E L
2001-01-25
An alternative approach is described to evaluate the statistical nature of the breakup of shaped charge liners. Experimental data from ductile and brittle copper jets are analyzed in terms of velocity gradient, deviation of {Delta}V from linearity, R/S analysis, and the Hurst exponent within the coupled map lattice model. One-dimensional simulations containing 600 zones of equal mass and using distinctly different force-displacement curves are generated to simulate ductile and brittle behavior. A particle separates from the stretching jet when an element of material reaches the failure criterion. A simple model of a stretching rod using brittle, semi-brittle, and ductile force-displacement curves is in agreement with the experimental results for the Hurst exponent and the phase portraits and indicates that breakup is a correlated phenomenon.
Evolution model with a cumulative feedback coupling
NASA Astrophysics Data System (ADS)
Trimper, Steffen; Zabrocki, Knud; Schulz, Michael
2002-05-01
The paper is concerned with a toy model that generalizes the standard Lotka-Volterra equation for a certain population by introducing a competition between instantaneous and accumulative, history-dependent nonlinear feedback the origin of which could be a contribution from any kind of mismanagement in the past. The results depend on the sign of that additional cumulative loss or gain term of strength λ. In case of a positive coupling the system offers a maximum gain achieved after a finite time but the population will die out in the long time limit. In this case the instantaneous loss term of strength u is irrelevant and the model exhibits an exact solution. In the opposite case λ<0 the time evolution of the system is terminated in a crash after ts provided u=0. This singularity after a finite time can be avoided if u≠0. The approach may well be of relevance for the qualitative understanding of more realistic descriptions.
The standard model coupled to quantum gravitodynamics
NASA Astrophysics Data System (ADS)
Aldabe, Fermin
2017-01-01
We show that the renormalizable SO(4)× U(1)× SU(2)× 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.
The CHIC Model: A Global Model for Coupled Binary Data
ERIC Educational Resources Information Center
Wilderjans, Tom; Ceulemans, Eva; Van Mechelen, Iven
2008-01-01
Often problems result in the collection of coupled data, which consist of different N-way N-mode data blocks that have one or more modes in common. To reveal the structure underlying such data, an integrated modeling strategy, with a single set of parameters for the common mode(s), that is estimated based on the information in all data blocks, may…
Two-mode coupling model in a few mode fiber
NASA Astrophysics Data System (ADS)
Kaliteevskiy, N. A.; Korolev, A. E.; Koreshkov, K. S.; Nazarov, V. N.; Sterlingov, P. M.
2013-06-01
A phenomenological two-mode coupling model in few mode fibers (FMF) is developed. It uses a mode coupling coefficient and the differential modal delay as the input parameters and the split-step approach. The model is consistent with the experimental results demonstrating distributed mode coupling effects in FMF and may be used for multipath interference estimation based on statistical analysis of fluctuations.
Teaching Couples Counseling: An Integrative Model
ERIC Educational Resources Information Center
Long, Lynn L.; Burnett, Judith A.
2005-01-01
Traditionally, training in couples counseling has not received equal status as other counseling modalities. Recently, there is renewed interest in specific training for couples counseling as more emphasis is placed on the stability of couple relationships as an important factor for helping families and children function in a society of frequent…
[Changes of plasma endocrine hormone in pilots under Coriolis acceleration].
Dai, Y; Ji, G; Huang, Y; Sun, X; Dai, F
1998-04-01
Plasma endocrine hormones were studied in both 24 motion sickness (orthostatic intolerance) and healthy pilots. Coriolis acceleration of 3.75, 5.00 and 6.25 pi 2 cm/s2 were given with intervals of 3-4 min AT-II, insulin, cortisol, Aldosterone and gastrin were determined by radioimmunoassay. It was found that aldosterone, AT-II, gastrin increased with increase of coriolis acceleration in all pilots. (P < 0.05), but cortisol and insulin only increased in healthy pilots (P < 0.05). It suggests excitation of the autonomic nervous system might be insufficient in orthostatic intolerant pilots and that determination of endocrine hormones may be useful in the evaluation of autonomic nervous activities.
Parametric excitation of a micro Coriolis mass flow sensor
NASA Astrophysics Data System (ADS)
Droogendijk, H.; Groenesteijn, J.; Haneveld, J.; Sanders, R. G. P.; Wiegerink, R. J.; Lammerink, T. S. J.; Lötters, J. C.; Krijnen, G. J. M.
2012-11-01
We demonstrate that a micro Coriolis mass flow sensor can be excited in its torsional movement by applying parametric excitation. Using AC-bias voltages for periodic electrostatic spring softening, the flow-filled tube exhibits a steady vibration at suitable voltage settings. Measurements show that the sensor for this type of excitation can be used to measure water flow rates within a range of 0 ± 500 μl/h with an accuracy of 1% full scale error.
Low-temperature linear thermal rectifiers based on Coriolis forces.
Suwunnarat, Suwun; Li, Huanan; Fleischmann, Ragnar; Kottos, Tsampikos
2016-04-01
We demonstrate that a three-terminal harmonic symmetric chain in the presence of a Coriolis force, produced by a rotating platform that is used to place the chain, can produce thermal rectification. The direction of heat flow is reconfigurable and controlled by the angular velocity Ω of the rotating platform. A simple three-terminal triangular lattice is used to demonstrate the proposed principle.
Long Term Stability of Coriolis Flow Meters: DESY experience
NASA Astrophysics Data System (ADS)
Boeckmann, T.; Bozhko, Y.; Escherich, K.; Petersen, B.; Putselyk, S.; Schnautz, T.; Sellmann, D.; Zhirnov, A.
2017-02-01
The measurement of coolant flow is important operational parameter for reliable operation of cryogenic system with superconducting magnets or cavities as well as for the system diagnostics in case of non-steady-state operation, e.g. during cool-down/warm-up or other transients. Proper flowmeter is chosen according to the different parameters, e.g. turn-down, operating temperature range, leak-tightness, pressure losses, long-term stability, etc. For helium cryogenics, the Venturi tube or Orifice, as well as Coriolis flow meters are often applied. For the present time, the orifices are usually used due to their simplicity and low costs, however, low turn-down range, large pressure drop, restriction of flow area, susceptibility to thermoacoustic oscillations limit their useful operation range. Operational characteristics of Venturi tubes is substantially improved in comparison to orifices, however, relative high costs and susceptibility to thermoacoustic oscillations still limit their application to special cases. The Coriolis flow meters do not have typical drawbacks of Venturi tube and orifices, however long-term stability over many years was not demonstrated yet. This paper describes the long-term behaviour of Coriolis flow meters after many years of operation at AMTF and XMTS facilities.
A fjord-glacier coupled system model
NASA Astrophysics Data System (ADS)
de Andrés, Eva; Otero, Jaime; Navarro, Francisco; Prominska, Agnieszka; Lapazaran, Javier; Walczowski, Waldemar
2017-04-01
With the aim of studying the processes occurring at the front of marine-terminating glaciers, we couple a fjord circulation model with a flowline glacier dynamics model, with subglacial discharge and calving, which allows the calculation of submarine melt and its influence on calving processes. For ocean modelling, we use a general circulation model, MITgcm, to simulate water circulation driven by both fjord conditions and subglacial discharge, and for calculating submarine melt rates at the glacier front. To constrain freshwater input to the fjord, we use estimations from European Arctic Reanalysis (EAR). To determine the optimal values for each run period, we perform a sensitivity analysis of the model to subglacial discharge variability, aimed to get the best fit of model results to observed temperature and salinity profiles in the fjord for each of these periods. Then, we establish initial and boundary fjord conditions, which we vary weekly-fortnightly, and calculate the submarine melt rate as a function of depth at the calving front. These data are entered into the glacier-flow model, Elmer/Ice, which has been added a crevasse-depth calving model, to estimate the glacier terminus position at a weekly time resolution. We focus our study on the Hansbreen Glacier-Hansbukta Fjord system, in Southern Spitsbergen, Svalbard, where a large set of data are available for both glacier and fjord. The bathymetry of the entire system has been determined from ground penetrating radar and sonar data. In the fjord we have got temperature and salinity data from CTDs (May to September, 2010-2014) and from a mooring (September to May, 2011-2012). For Hansbreen, we use glacier surface topography data from the SPIRIT DEM, surface mass balance from EAR, centre line glacier velocities from stake measurements (May 2005-April 2011), weekly terminus positions from time-lapse photos (Sept. 2009-Sept. 2011), and sea-ice concentrations from time-lapse photos and Nimbus-7 SMMR and DMSP SSM
Extended source model for diffusive coupling.
González-Ochoa, Héctor O; Flores-Moreno, Roberto; Reyes, Luz M; Femat, Ricardo
2016-01-01
Motivated by the prevailing approach to diffusion coupling phenomena which considers point-like diffusing sources, we derived an analogous expression for the concentration rate of change of diffusively coupled extended containers. The proposed equation, together with expressions based on solutions to the diffusion equation, is intended to be applied to the numerical solution of systems exclusively composed of ordinary differential equations, however is able to account for effects due the finite size of the coupled sources.
Parameterization of the Lorentz to Coriolis Force Ratio in Planetary Dynamos
NASA Astrophysics Data System (ADS)
Soderlund, K. M.; Sheyko, A. A.; King, E. M.; Aurnou, J. M.
2015-12-01
The Lorentz to Coriolis force ratio is an important parameter for the dynamics of planetary cores: it is expected that dynamos with dominant Coriolis forces will be driven by fundamentally different archetypes of fluid motions than those with co-dominant Lorentz forces. Using a suite of geodynamo simulations, we have tested several parameterizations of the Lorentz to Coriolis force ratio against direct calculations and developed a scaling estimate to predict this ratio for planetary cores. Our results suggest that the Earth's core is likely to be in magnetostrophic balance where the Lorentz and Coriolis forces are comparable. The Lorentz force may also be significant in Jupiter's core, where it is predicted to be approximately a factor of ten less than the Coriolis force. Magnetic fields become increasingly sub-dominant for the other planets: the Coriolis force is predicted to exceed the Lorentz force by at least two orders of magnitude within the cores of Saturn, Uranus/Neptune, Ganymede, and Mercury.
Coupling approaches used in atmospheric entry models
NASA Astrophysics Data System (ADS)
Gritsevich, M. I.
2012-09-01
While a planet orbits the Sun, it is subject to impact by smaller objects, ranging from tiny dust particles and space debris to much larger asteroids and comets. Such collisions have taken place frequently over geological time and played an important role in the evolution of planets and the development of life on the Earth. Though the search for near-Earth objects addresses one of the main points of the Asteroid and Comet Hazard, one should not underestimate the useful information to be gleaned from smaller atmospheric encounters, known as meteors or fireballs. Not only do these events help determine the linkages between meteorites and their parent bodies; due to their relative regularity they provide a good statistical basis for analysis. For successful cases with found meteorites, the detailed atmospheric path record is an excellent tool to test and improve existing entry models assuring the robustness of their implementation. There are many more important scientific questions meteoroids help us to answer, among them: Where do these objects come from, what are their origins, physical properties and chemical composition? What are the shapes and bulk densities of the space objects which fully ablate in an atmosphere and do not reach the planetary surface? Which values are directly measured and which are initially assumed as input to various models? How to couple both fragmentation and ablation effects in the model, taking real size distribution of fragments into account? How to specify and speed up the recovery of a recently fallen meteorites, not letting weathering to affect samples too much? How big is the pre-atmospheric projectile to terminal body ratio in terms of their mass/volume? Which exact parameters beside initial mass define this ratio? More generally, how entering object affects Earth's atmosphere and (if applicable) Earth's surface? How to predict these impact consequences based on atmospheric trajectory data? How to describe atmospheric entry
Lithosphere-Atmosphere-Ionosphere coupling model
NASA Astrophysics Data System (ADS)
Kachakhidze, M. K., III
2015-12-01
The present work offers interpretation of a mechanism of formation of hypothetic ideal electromagnetic contour, creation of which is envisaged in incoming earthquake focal zone. Model of generation of EM emissions detected before earthquake is based on physical analogues of distributed and conservative systems and focal zones. According to the model the process of earthquake preparation from the moment of appearance of cracks in the system, including completion of series of foreshocks, earthquake and aftershocks, are entirely explained by oscillating systems.According to the authors of the work electromagnetic emissions in radio diapason is more universal and reliable than other anomalous variations of various geophysical phenomena in earthquake preparation period; Besides, VLF/LF electromagnetic emissions might be declared as the main precursor of earthquake because it might turn out very useful with the view of prediction of large (M5) inland earthquakes and to govern processes going on in lithosphere-atmosphere-ionosphere coupling (LAIC) system. Based on this model, in case of electromagnetic emissions spectrum monitoring in the period that precedes earthquake it is possible to determine, with certain accuracy, the time, location and magnitude of an incoming earthquake simultaneously.The present item considers possible physical mechanisms of the geophysical phenomena, which may accompany earthquake preparation process and expose themselves several months, weeks or days prior to earthquakes. Such as: Changing of intensity of electro-telluric current in focal area; Perturbations of geomagnetic field in forms of irregular pulsations or regular short-period pulsations; Perturbations of atmospheric electric field; Irregular changing of characteristic parameters of the lower ionosphere (plasma frequency, electron concentration, height of D layer, etc.); Irregular perturbations reaching the upper ionosphere, namely F2-layer, for 2-3 days before the earthquake
Effect of coriolis force on forced response magnification of intentionally mistuned bladed disk
NASA Astrophysics Data System (ADS)
Kan, Xuanen; Xu, Zili; Zhao, Bo; Zhong, Jize
2017-07-01
Blade manufacturing tolerance and wear in operation may induce mistuning, and mistuning will lead to vibration localization which will result in destruction of bladed disk. Generally, intentional mistuning has been widely investigated to control the maximum forced response. On the other hand, it should be noted that the bladed disk with high rotational speed is obviously subjected to the Coriolis force. However, the Coriolis force is not included in intentionally mistuned bladed disk in previous studies. Therefore, this paper is to study the effect of the Coriolis force on forced response magnification of intentionally mistuned bladed disk. Finite element method is used to calculate the harmonic response of the intentionally mistuned bladed disk with and without the Coriolis force. The effects of intentional mistuning strength and different integer harmonic order on the response magnification factor with the Coriolis force are discussed. It should be pointed out that, when the integer harmonic order is 1, 3 and 5, the response magnification factor with the effect of the Coriolis force increase by 3.9%, 3.53% and 3.76% respectively compared to the system of non-Coriolis force. In addition, forced response magnification factor of intentionally mistuned bladed disk with and without the Coriolis force under different rotational speed is researched in contrast. It shows that, when the rotational speed is 3000 rpm, the response magnification factor with the Coriolis force increases by 0.65% compared to the system of non-Coriolis force, while the response magnification factor with the Coriolis force decreases by 6.28% compared to the system of non-Coriolis force when the rotational speed is 12000 rpm.
A critique of the chemosmotic model of energy coupling.
Green, D E
1981-04-01
The chemosmotic model provides a framework for visualizing energy-coupled reactions (vectorial reaction sequences, membrane-dependent gradient formation, and charge separation of reacting species) and a mechanism for energy coupling (indirect coupling between the driving and driven reaction sequences mediated by a membrane potential or a protonmotive force). The mechanistic parameters of this model have been examined from four standpoints: compatibility with the experimental realities, supporting evidence that is unambiguous, compatibility with the enzymic nature of energy coupling, and the capability for generating verifiable predictions. Recent developments that have clarified the mechanism of ion transport, the nature of the protonic changes that accompany energy coupling, and the enzymic nature of energy coupling systems have made such an examination both timely and necessary. After weighing the available evidence, it has been concluded that the chemosmotic principle of indirect coupling has no basis in fact and that it is physically unsound in respect to the mechanism of energy coupling and enzymic catalysis.
Madden-Julian Variability in Coupled Models
Sperber, K R; Gualdi, S; Li, W; Slingo, J M
2001-12-12
The Madden-Julian Oscillation (MJO) is a dominant mode of tropical variability (Madden and Julian 1971, 1972). It is manifested on a timescale of {approx}30-70 days through large-scale circulation anomalies which occur in conjunction with eastward propagating convective anomalies over the eastern hemisphere. Recent evidence has suggested that an interactive ocean may be important for the simulation of the Madden-Julian Oscillation (Flatau et al. 1997, Sperber et al. 1997, Waliser et al. 1999, Inness et al. 2002). As part of an initiative to the CLIVAR Working Group on Coupled Modeling, we examine ocean-atmosphere GCMs to ascertain the degree to which they can represent the 4-dimensional space-time structure of the MJO. The eastward propagation of convection is also examined with respect to the surface fluxes and SST, and we compare and contrast the behavior over the Indian Ocean and the western Pacific. Importantly, the results are interpreted with respect to systematic error of the mean state.
An Integration and Evaluation Framework for ESPC Coupled Models
2014-09-30
Models PI: Ben Kirtman University of Miami – RSMAS Atmospheric Sciences 4600 Rickenbacker Causeway Miami, FL 33149 Phone: (305) 421-4046...annual report. 7 ESPC Testbed: Interactive ensemble Initial prototype of multi- model interactive ensemble coupling infrastructure. Initial...get HYCOM integrated. Enhanced the interactive ensemble so that multiple atmosphere, land and ice component models can be simultaneously coupled
Modeling of coupled hydro-mechanical problem for porous media
NASA Astrophysics Data System (ADS)
Koudelka, T.; Krejci, T.; Broucek, M.
2013-10-01
The paper deals with numerical modelling of coupled hydro-mechanical problem for porous media. It is focused on coupled hydro-mechanical models for saturated - partially saturated soils. These models were implemented to the SIFEL software package and they were used for numerical simulation of a plate settlement experiment.
Esposti; Fuganti; Kisiel; Tamassia
1998-10-01
The millimeter-wave rotational spectra of 79BrNO and 81BrNO in the v2 = 1 and v3 = 2 vibrational states have been reinvestigated. Measurements of the rotational spectrum in the region of maximum c-type Coriolis interaction between the two states allowed the previous analysis to be extended to account for some uncommon effects. For the most perturbed transitions the nuclear quadrupole hyperfine structure arises from coupling of not only the bromine nucleus, but also the nitrogen nucleus with the rotational angular momentum. These effects were satisfactorily fitted with a Hamiltonian describing Coriolis coupling in a molecule with two quadrupolar nuclei. The successful analysis of pure rotational transitions then allowed accurate prediction of rovibrational transitions, six of which were measured for 79BrNO and four for 81BrNO. Copyright 1998 Academic Press.
NASA Astrophysics Data System (ADS)
Benjamin, Stan; Sun, Shan; Grell, Georg; Green, Benjamin; Bleck, Rainer; Li, Haiqin
2017-04-01
Extreme events for subseasonal duration have been linked to multi-week processes related to onset, duration, and cessation of blocking events or, more generally, quasi-stationary waves. Results will be shown from different sets of 32-day prediction experiments (3200 runs each) over a 16-year period for earth system processes key for subseasonal prediction for different resolution, numerics, and physics using the FIM-HYCOM coupled model. The coupled atmosphere (FIM) and ocean (HYCOM) modeling system is a relatively new coupled atmosphere-ocean model developed for subseasonal to seasonal prediction (Green et al. 2017 Mon.Wea.Rev. accepted, Bleck et al 2015 Mon. Wea. Rev.). Both component models operate on a common icosahedral horizontal grid and use an adaptive hybrid vertical coordinate (sigma-isentropic in FIM and sigma-isopycnic in HYCOM). FIM-HYCOM has been used to conduct 16 years of subseasonal retrospective forecasts following the NOAA Subseasonal (SubX) NMME protocol (32-day forward integrations), run with 4 ensemble members per week. Results from this multi-year FIM-HYCOM hindcast include successful forecasts out to 14-20 days for stratospheric warming events (from archived 10 hPa fields), improved MJO predictability (Green et al. 2017) using the Grell-Freitas (2014, ACP) scale-aware cumulus scheme instead of the Simplified Arakawa-Schubert scheme, and little sensitivity to resolution for blocking frequency. Forecast skill of metrics from FIM-HYCOM including 500 hPa heights and MJO index is at least comparable to that of the operational Climate Forecast System (CFSv2) used by the National Centers for Environmental Prediction. Subseasonal skill is improved with a limited multi-model (FIM-HYCOM and CFSv2), consistent with previous seasonal multi-model ensemble results. Ongoing work will also be reported on for adding inline aerosol/chemistry treatment to the coupled FIM-HYCOM model and for advanced approaches to subgrid-scale clouds to address regional biases
Coupling Climate Models and Forward-Looking Economic Models
NASA Astrophysics Data System (ADS)
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
A New Coupled 4DVAR Assimilation System for Coupled Ocean-Wave Models
NASA Astrophysics Data System (ADS)
Blain, C. A.; Orzech, M.; Carrier, M.; Ngodock, H.; Souopgui, I.; Smith, S. R.
2016-02-01
The coastal ocean environment poses prediction challenges due to shortened time and space scales and highly nonlinear interactions between its wave and circulation dynamics. In-situ observations in such a region can often be scattered and/or incomplete, further stressing our ability to accurately forecast coastal parameters such as currents, wave heights and direction, and density structure. To extend predictability in these coastal environments, we have developed a coupled, four-dimensional, variational (4DVAR) assimilation system for coupled ocean-wave models. Coupling the assimilation systems for the ocean and waves insures dynamical consistency of the assimilation innovations in a highly nonlinear, continuously evolving environment. Coupled assimilation also permits observations of one process to affect the forecast of another, which can maximize our use of limited datasets. The ocean-wave assimilation system is presently coupled through three mechanisms: ocean currents, Stokes' drift, and wave radiation stress gradients, and is incorporated within the Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS). The coupled assimilation is realized by including each of these coupling terms within the adjoint and tangent linear components of the ocean-wave, 4DVAR assimilation system. The ocean-wave assimilation and forecast system is then applied to a series of twin experiments near the mouth of Chesapeake Bay. These twin experiments are designed to show how information flows from observations assimilated in to either the ocean or wave model through the coupled assimilation to influence both ocean and wave model variables. Inferred corrections from one system to another are demonstrated. As part of the coupled assimilation system, a newly developed formulation for wave error covariances is implemented. Impacts of the wave covariances on predictions from the coupled ocean-wave model system are also assessed.
Tropical cyclone sensitivity to ocean coupling in the ECMWF coupled model
NASA Astrophysics Data System (ADS)
Mogensen, Kristian S.; Magnusson, Linus; Bidlot, Jean-Raymond
2017-05-01
We present an investigation of the performance of the ECMWF coupled atmosphere-waves-ocean model for different ocean and atmosphere resolutions on a series of tropical cyclones in the Western Pacific with the aim to better understand the coupled feedback mechanisms in these extreme conditions. For some of the test cases, we only find little impact of coupling the atmosphere to the ocean, while in others, we observe a very large impact. To further understand these differences, we have selected two tropical cyclones (TCs) as case studies: TC Haiyan (with small impact of coupling) and TC Neoguri (with large impact of coupling). The comparison between these two cases suggests that the upper ocean stratification is the key in determining the strength of the coupled feedback. A strong coupled feedback is found whenever the ocean heat content of the upper layer is low while a very weak coupled feedback is found whenever the ocean has a thick warm mixed layer. The oceanographic response to tropical cyclones for the two storms has been compared to sea surface temperature and derived surface currents from drifting buoys and to subsurface observations from Argo and ship launched XBT's. These comparisons show that we are able to realistically reproduce the atmospheric and oceanographic interaction during tropical cyclone conditions which gives us confidence that the coupled modeling system is physically sound.
A small signal coupling model for predicting the coupling between LNAs
NASA Astrophysics Data System (ADS)
Shi, Junyu; Cui, Dasheng; Wu, Yuming
2017-07-01
A small signal coupling model is developed to analyze the coupling between two LNAs. The mutual inductance between the adjacent on-chip inductors is considered responsible for this coupling. A set of formulas have been derived to quantitatively predict the coupling effects. Based on our analysis, a quick estimation can be made to see which pair of inductors plays a key role in evaluating the coupling between the LNAs. Source inductors of two LNAs are placed closely while the load inductors are far apart according to the analysis. To validate the proposed theory, two 2 GHz LNAs are fabricated. The LNAs have a peak gain of 18 dB and NF of 1.4 dB. The coupling between the LNAs is -30 dB. Project supported by the National Natural Science Foundation of China (No. 61401025).
Influence of the Coriolis force in atom interferometry.
Lan, Shau-Yu; Kuan, Pei-Chen; Estey, Brian; Haslinger, Philipp; Müller, Holger
2012-03-02
In a light-pulse atom interferometer, we use a tip-tilt mirror to remove the influence of the Coriolis force from Earth's rotation and to characterize configuration space wave packets. For interferometers with a large momentum transfer and large pulse separation time, we improve the contrast by up to 350% and suppress systematic effects. We also reach what is to our knowledge the largest space-time area enclosed in any atom interferometer to date. We discuss implications for future high-performance instruments.
Time-delayed coupled logistic capacity model in population dynamics
NASA Astrophysics Data System (ADS)
Cáceres, Manuel O.
2014-08-01
This study proposes a delay-coupled system based on the logistic equation that models the interaction of a population with its varying environment. The integro-diferential equations of the model are presented in terms of a distributed time-delayed coupled logistic-capacity equation. The model eliminates the need for a prior knowledge of the maximum saturation environmental carrying capacity value. Therefore the dynamics toward the final attractor in a distributed time-delayed coupled logistic-capacity model is studied. Exact results are presented, and analytical conclusions have been done in terms of the two parameters of the model.
Quark-meson coupling model with the cloudy bag
Nagai, S.; Miyatsu, T.; Saito, Kenji; Tsushima, Kazuo
2008-07-01
Using the volume coupling version of the cloudy bag model, the quark-meson coupling model is extended to study the role of pion field and the properties of nuclear matter. The extended model includes the effect of gluon exchange as well as the pion-cloud effect, and provides a good description of the nuclear matter properties. The relationship between the extended model and the EFT approach to nuclear matter is also discussed.
CIDGA - Coupling of Interior Dynamic models with Global Atmosphere models
NASA Astrophysics Data System (ADS)
Noack, Lena; Plesa, Ana-Catalina; Breuer, Doris
2010-05-01
Atmosphere temperatures and in particular the surface temperatures mostly depend on the solar heat flux and the atmospheric composition. The latter can be influenced by interior processes of the planet, i.e. volcanism that releases greenhouse gases such as H2O, CO2 and methane into the atmosphere and plate tectonics through which atmospheric CO2 is recycled via carbonates into the mantle. An increasing concentration of greenhouse gases in the atmosphere results in an increase of the surface temperature. Changes in the surface temperature on the other hand may influence the cooling behaviour of the planet and hence influence its volcanic activity [Phillips et al., 2001]. This feedback relation between mantle convection and atmosphere is not very well understood, since until now mostly either the interior dynamic of a planet or its atmosphere was investigated separately. 2D or 3D mantle convection models to the authors' knowledge haven't been coupled to the atmosphere so far. We have used the 3D spherical simulation code GAIA [Hüttig et al., 2008] including partial melt production and coupled it with the atmosphere module CIDGA using a gray greenhouse model for varying H2O concentrations. This way, not only the influence of mantle dynamics on the atmosphere can be investigated, but also the recoupling effect, that the surface temperature has on the mantle dynamics. So far, we consider one-plate planets without crustal and thus volatile recycling. Phillips et al. [2001] already investigated the coupling effect of the surface temperature on mantle dynamics by using simple parameterized convection models for Venus. In their model a positive feedback mechanism has been observed, i.e., an increase of the surface temperature leads to an increase of partial melt and hence an increase of atmosphere density and surface temperature. Applying our model to Venus, we show that an increase of surface temperature leads not only to an increase of partial melt in the mantle; it also
Coriolis analysis of several high-resolution infrared bands of bicyclo[1 1 1]pentane-d0 and -d1
NASA Astrophysics Data System (ADS)
Perry, A.; Martin, M. A.; Nibler, J. W.; Maki, A.; Weber, A.; Blake, T. A.
2012-06-01
High-resolution infrared absorption spectra have been analyzed for two bicyclo[1 1 1]pentane isotopologues, C5H8 (-d0) and C5H7D (-d1), where in the latter the D-atom replaces a hydrogen on the C3 symmetry axis such that the molecular symmetry is reduced from D3h to C3v. Two (a2″) parallel bands, ν17 and ν18, of bicyclopentane-d0 were studied and the former was found to be profoundly affected by Coriolis coupling with the nearby (e') perpendicular band, ν11. Weaker coupling was observed between the ν18 band and the nearby ν13(e') band, for which fewer transitions could be assigned. For bicyclopentane-d1, the ν5 parallel band was also studied along with the nearby ν15(e') band to which it is coupled through a similar type of Coriolis resonance. For both isotopologues, quantum calculations (B3LYP/cc-pVTZ) done at the anharmonic level were very helpful in unraveling the complexities caused by the Coriolis interactions, provided that care is taken in identifying the effect of any Coriolis resonances on the theoretical values of αB and q rovibrational parameters. The ground state B0 constants were found to be 0.2399412(2) and 0.2267506(11) cm-1 for the -d0 and -d1 isotopologues. The difference yields an Rs substitution value of 2.0309(2) Å for the position of the axial H atom relative to the -d0 center of mass, a result in good accord with a corresponding Ra value of 2.044(6) Å from electron diffraction data. For both isotopologues, the theoretical results from the quantum calculations are in good agreement with all corresponding values determined from the spectra.
Tinamit: Making coupled system dynamics models accessible to stakeholders
NASA Astrophysics Data System (ADS)
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
Absolute rotation detection by Coriolis force measurement using optomechanics
NASA Astrophysics Data System (ADS)
Davuluri, Sankar; Li, Yong
2016-10-01
In this article, we present an application of the optomechanical cavities for absolute rotation detection. Two optomechanical cavities, one in each arm, are placed in a Michelson interferometer. The interferometer is placed on a rotating table and is moved with a uniform velocity of \\dot{\\bar{y}} with respect to the rotating table. The Coriolis force acting on the interferometer changes the length of the optomechanical cavity in one arm, while the length of the optomechanical cavity in the other arm is not changed. The phase shift corresponding to the change in the optomechanical cavity length is measured at the interferometer output to estimate the angular velocity of the absolute rotation. An analytic expression for the minimum detectable rotation rate corresponding to the standard quantum limit of measurable Coriolis force in the interferometer is derived. Squeezing technique is discussed to improve the rotation detection sensitivity by a factor of \\sqrt{{γ }m/{ω }m} at 0 K temperature, where {γ }m and {ω }m are the damping rate and angular frequency of the mechanical oscillator. The temperature dependence of the rotation detection sensitivity is studied.
Coupled and uncoupled dipole models of nonlinear scattering.
Balla, Naveen K; Yew, Elijah Y S; Sheppard, Colin J R; So, Peter T C
2012-11-05
Dipole models are one of the simplest numerical models to understand nonlinear scattering. Existing dipole model for second harmonic generation, third harmonic generation and coherent anti-Stokes Raman scattering assume that the dipoles which make up a scatterer do not interact with one another. Thus, this dipole model can be called the uncoupled dipole model. This dipole model is not sufficient to describe the effects of refractive index of a scatterer or to describe scattering at the edges of a scatterer. Taking into account the interaction between dipoles overcomes these short comings of the uncoupled dipole model. Coupled dipole model has been primarily used for linear scattering studies but it can be extended to predict nonlinear scattering. The coupled and uncoupled dipole models have been compared to highlight their differences. Results of nonlinear scattering predicted by coupled dipole model agree well with previously reported experimental results.
Coupling of the Models of Human Physiology and Thermal Comfort
NASA Astrophysics Data System (ADS)
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.
Modeling of Inner Magnetosphere Coupling Processes
NASA Technical Reports Server (NTRS)
Khazanov, George V.
2011-01-01
The Ring Current (RC) is the biggest energy player in the inner magnetosphere. It is the source of free energy for Electromagnetic Ion Cyclotron (EMIC) wave excitation provided by a temperature anisotropy of RC ions, which develops naturally during inward E B convection from the plasmasheet. The cold plasmasphere, which is under the strong influence of the magnetospheric electric field, strongly mediates the RC-EMIC wave-particle-coupling process and ultimately becomes part of the particle and energy interplay. On the other hand, there is a strong influence of the RC on the inner magnetospheric electric and magnetic field configurations and these configurations, in turn, are important to RC dynamics. Therefore, one of the biggest needs for inner magnetospheric research is the continued progression toward a coupled, interconnected system with the inclusion of nonlinear feedback mechanisms between the plasma populations, the electric and magnetic fields, and plasma waves. As we clearly demonstrated in our studies, EMIC waves strongly interact with electrons and ions of energies ranging from approx.1 eV to approx.10 MeV, and that these waves strongly affect the dynamics of resonant RC ions, thermal electrons and ions, and the outer RB relativistic electrons. As we found, the rate of ion and electron scattering/heating in the Earth's magnetosphere is not only controlled by the wave intensity-spatial-temporal distribution but also strongly depends on the spectral distribution of the wave power. The latter is also a function of the plasmaspheric heavy ion content, and the plasma density and temperature distributions along the magnetic field lines. The above discussion places RC-EMIC wave coupling dynamics in context with inner magnetospheric coupling processes and, ultimately, relates RC studies with plasmaspheric and Superthermal Electrons formation processes as well as with outer RB physics.
Ocean Data Assimilation for Coupled Models
2016-06-07
ability to analyze and predict the upper ocean/lower atmosphere environment, using sophisticated techniques that can exploit data from all available...sources. This ability is fundamental to meeting DOD’s needs for real-time analysis and improved air/sea simulation and prediction on a variety of scales...is developing the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS), and has already transitioned the atmospheric prediction system and
Modification of Higgs couplings in minimal composite models
NASA Astrophysics Data System (ADS)
Liu, Da; Low, Ian; Wagner, Carlos E. M.
2017-08-01
We present a comprehensive study of the modifications of Higgs couplings in the S O (5 )/S O (4 ) minimal composite model. We focus on three couplings of central importance to Higgs phenomenology at the LHC: the couplings to top and bottom quarks and the coupling to two gluons. We consider three possible embeddings of the fermionic partners in 5 , 10 and 14 of S O (5 ) and find t t ¯h and b b ¯h couplings to be always suppressed in 5 and 10 , while in 14 they can be either enhanced or suppressed. Assuming partial compositeness, we analyze the interplay between the t t ¯h coupling and the top sector contribution to the Coleman-Weinberg potential for the Higgs boson, and the correlation between t t ¯h and g g h couplings. In particular, if the electroweak symmetry breaking is triggered radiatively by the top sector, we demonstrate that the ratio of the t t ¯h coupling in composite Higgs models over the Standard Model expectation is preferred to be less than the corresponding ratio of the g g h coupling.
Exact solutions for a coupled nonlocal model of nanobeams
Marotti de Sciarra, Francesco E-mail: raffaele.barretta@unina.it; Barretta, Raffaele E-mail: raffaele.barretta@unina.it
2014-10-06
BERNOULLI-EULER nanobeams under concentrated forces/couples with the nonlocal constitutive behavior proposed by ERINGEN do not exhibit small-scale effects. A new model obtained by coupling the ERINGEN and gradient models is formulated in the present note. A variational treatment is developed by imposing suitable thermodynamic restrictions for nonlocal models and the ensuing differential and boundary conditions of elastic equilibrium are provided. The nonlocal elastostatic problem is solved in a closed-form for nanocantilever and clamped nanobeams.
Coupling entropy of co-processing model on social networks
NASA Astrophysics Data System (ADS)
Zhang, Zhanli
2015-08-01
Coupling entropy of co-processing model on social networks is investigated in this paper. As one crucial factor to determine the processing ability of nodes, the information flow with potential time lag is modeled by co-processing diffusion which couples the continuous time processing and the discrete diffusing dynamics. Exact results on master equation and stationary state are achieved to disclose the formation. In order to understand the evolution of the co-processing and design the optimal routing strategy according to the maximal entropic diffusion on networks, we propose the coupling entropy comprehending the structural characteristics and information propagation on social network. Based on the analysis of the co-processing model, we analyze the coupling impact of the structural factor and information propagating factor on the coupling entropy, where the analytical results fit well with the numerical ones on scale-free social networks.
Predictive Models for Hydrodynamic Coupling Coefficients in Clay Media.
NASA Astrophysics Data System (ADS)
Gueutin, P.; Gonçalvès, J.; Violette, S.
2007-12-01
In charged and low permeability media (e.g. clay media) the classical Darcy's law does not describe accurately the water movement. A generalized Darcy's law, one of the coupled fluxes equations, has to be used. The identification of the coupling parameters, in clay-rocks, is crucial in order to estimate the water flow. Here, we will only focus on the electrochemical-hydraulic coupling coefficients : the intrinsic permeability k and the osmotic permeability kc. These hydrodynamic coupling coefficients can be estimated using two approaches: (i) theoretical models : • porosity/intrinsic permeability relationships, defined for a clay medium, are used to estimate the intrinsic permeability. • an electrochemical model is used to estimate the osmotic coupling coefficient. The electrical model, a triple layer model, is implemented to simulate the interactions between the charged surfaces of the clay minerals and the pore solution. (ii) experiments : • at the sample scale. • at the field scale. The measurement of these parameters is generally challenging either at the sample or at the field scale. For this reason, predictive models can be useful. The purpose of this study is to give reference values for the two coupling parameters under consideration here, using to the petrophysical properties of the medium. Different models to estimate these coupling coefficients are tested : (i) the intrinsic permeability is estimated with a pretrophysical model. In this model, the intrinsic permeability depends on the effective pore radius and the electrical formation factor. (ii) the osmotic coupling coefficient is estimated with the model developed by Revil and Leroy (2004). The comparison between three different models with the available data shows that these data are more closely reproduced using this model. Some reference values are provided for several type of clays as a fonction of some readily measurable or estimable parameters or variables, such as the porosity, the
2011-09-30
Hydrographischen Zeitschrift Reihe 12. Moon I-J, I. Ginis, and T. Hara, 2004: Effect of surface waves on Charnock coefficient under tropical cyclones: Geophy...coupling parameterizations of the wind-wave-current interaction and sea spray effects and implement them in the unified module, • implement the...surface gravity waves modify the momentum flux to subsurface currents via three mechanisms (the Coriolis-Stokes effect , the air-sea momentum budget, and
Coupled-channel scattering in 1 + 1 dimensional lattice model
Guo, Peng
2013-07-01
Based on the Lippmann-Schwinger equation approach, a generalized Lüscher’s formula in 1+1 dimensions for two particles scattering in both the elastic and coupled-channel cases in moving frames is derived. A two-dimensional coupled-channel scattering lattice model is presented, which represents a two-coupled-channel resonant scattering scalars system. The Monte Carlo simulation is performed on finite lattices and in various moving frames. The two-dimensional generalized Lüscher’s formula is used to extract the scattering amplitudes for the coupled-channel system from the discrete finite-volume spectrum.
Aircraft Measurements for Understanding Air-Sea Coupling and Improving Coupled Model Predictions
2013-09-30
measured solar /IR irradiance profiles as input to, and validation of, the Navy’s coupled ocean/atmosphere model , COAMPS. FY13 effort focused on...coupling in different stages of the MJO. The objectives of the NRL project are to obtain vertical profiles of the solar and IR irradiance ...of the NRL solar and IR broadband radiometer irradiance data from the NOAA P-3 aircraft was completed. QC’ed datasets, with documentation, of the
Overview of the Coupled Model Intercomparison Project (CMIP)
Meehl, G A; Covey, C; McAvaney, B; Latif, M; Stouffer, R J
2004-08-05
The Coupled Model Intercomparison Project (CMIP) is designed to allow study and intercomparison of multi-model simulations of present-day and future climate. The latter are represented by idealized forcing of compounded 1% per year CO2 increase to the time of CO2 doubling near year 70 in simulations 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 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 Nino 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 is now usually around 2.5 degrees 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 model resolutions of around 1.5 degrees latitude-longitude. Modeling groups now routinely run the CMIP control and 1% CO2 simulations in addition to 20th and 21st century climate simulations with a variety of forcings (e.g. volcanoes, solar variability, anthropogenic sulfate aerosols, ozone, and greenhouse gases (GHGs), with the anthropogenic forcings for future climate as well). However, persistent systematic errors noted in previous generations of global coupled models still are present
Spectral classification of coupling regimes in the quantum Rabi model
NASA Astrophysics Data System (ADS)
Rossatto, Daniel Z.; Villas-Bôas, Celso J.; Sanz, Mikel; Solano, Enrique
2017-07-01
The quantum Rabi model is in the scientific spotlight due to the recent theoretical and experimental progress. Nevertheless, a full-fledged classification of its coupling regimes remains as a relevant open question. We propose a spectral classification dividing the coupling regimes into three regions based on the validity of perturbative criteria on the quantum Rabi model, which allows us the use of exactly solvable effective Hamiltonians. These coupling regimes are (i) the perturbative ultrastrong coupling regime which comprises the Jaynes-Cummings model, (ii) a region where nonperturbative ultrastrong and nonperturbative deep strong coupling regimes coexist, and (iii) the perturbative deep strong coupling regime. We show that this spectral classification depends not only on the ratio between the coupling strength and the natural frequencies of the unperturbed parts, but also on the energy to which the system can access. These regimes additionally discriminate the completely different behaviors of several static physical properties, namely the total number of excitations, the photon statistics of the field, and the cavity-qubit entanglement. Finally, we explain the dynamical properties which are traditionally associated with the deep strong coupling regime, such as the collapses and revivals of the state population, in the frame of the proposed spectral classification.
Building Ensemble-Based Data Assimilation Systems with Coupled Models
NASA Astrophysics Data System (ADS)
Nerger, Lars
2017-04-01
Discussed is the construction of programs for efficient ensemble data assimilation systems based on a direct connection between a coupled simulation model and ensemble data assimilation software. The strategy allows us to set up a data assimilation program with high flexibility and parallel scalability with only small changes to the model. The direct connection is obtained by first extending the source code of the coupled model so that it is able to run an ensemble of model states. In addition, a filtering step is added using a combination of in-memory access and parallel communication to create an online-coupled ensemble assimilation program. The direct connection avoids the common need to stop and restart a whole coupled model system to perform the assimilation of observations in the analysis step of ensemble-based filter methods like ensemble Kalman or particle filters. Instead, the analysis step is performed in between time steps and is independent of the actual model coupler. This strategy allows us to perform both in-compartment (for weakly coupled assimilation) and cross-compartment (for strongly coupled assimilation) assimilation. The assimilation frequency can be kept flexible, so that assimilation of observations from different compartments can be performed at different time intervals. Using the parallel data assimilation framework (PDAF, http://pdaf.awi.de), the direct connection strategy will be exemplified for the ocean-atmosphere model ECHAM6-FESOM.
Modeling Pancake Formation with a Coupled Wave-Ice Model
NASA Astrophysics Data System (ADS)
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.
Coupled thermomechanical modeling using dissimilar geometries in arpeggio.
Kostka, Timothy D.; Templeton, Jeremy Alan
2010-11-01
Performing coupled thermomechanical simulations is becoming an increasingly important aspect of nuclear weapon (NW) safety assessments in abnormal thermal environments. While such capabilities exist in SIERRA, they have thus far been used only in a limited sense to investigate NW safety themes. An important limiting factor is the difficulty associated with developing geometries and meshes appropriate for both thermal and mechanical finite element models, which has limited thermomechanical analysis to simplified configurations. This work addresses the issue of how to perform coupled analyses on models where the underlying geometries and associated meshes are different and tailored to their relevant physics. Such an approach will reduce the model building effort and enable previously developed single-physics models to be leveraged in future coupled simulations. A combined-environment approach is presented in this report using SIERRA tools, with quantitative comparisons made between different options in SIERRA. This report summarizes efforts on running a coupled thermomechanical analysis using the SIERRA Arpeggio code.
Unification of gauge couplings in radiative neutrino mass models
NASA Astrophysics Data System (ADS)
Hagedorn, Claudia; Ohlsson, Tommy; Riad, Stella; Schmidt, Michael A.
2016-09-01
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. We study three representative classes of radiative neutrino mass models: (I) minimal ultraviolet completions of the dimension-7 Δ L = 2 operators which generate neutrino masses at one- and/or two-loop level without and with dark matter candidates, (II) models with dark matter which lead to neutrino 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), 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 5·1010 - 5·1014 GeV.
Modeling Excitable Systems Coupled Through External Medium
NASA Astrophysics Data System (ADS)
Noorbakhsh, Javad; Mehta, Pankaj
2013-03-01
Excitable systems are stable dynamical systems in which any input beyond a threshold results in a significant output. This behavior is ubiquitous in nature and is seen in biological systems such as Dictyostelium discoideum amoeba and neurons to oscillatory chemical reactions. In this work we will focus on transition to oscillation in populations of excitable systems coupled through an external medium and will study their synchronization. We will describe a mechanism to tune the frequency of oscillations using an external input and will study the effects of stochasticity and inhomogeneity on the collective behavior of the system. Furthermore we will include diffusion into the dynamics of the external medium and will study formation of spatial patterns, their characteristics and their robustness to different factors.
Nuclear Hybrid Energy System Modeling: RELAP5 Dynamic Coupling Capabilities
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.
Light weakly coupled axial forces: models, constraints, and projections
NASA Astrophysics Data System (ADS)
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.
Light Weakly Coupled Axial Forces: Models, Constraints, and Projections
Kahn, Yonatan; Krnjaic, Gordan; Mishra-Sharma, Siddharth; Tait, Tim P.
2016-09-28
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 pi^0 and 8-Be* decay.
Light weakly coupled axial forces: models, constraints, and projections
Kahn, Yonatan; Krnjaic, Gordan; Mishra-Sharma, Siddharth; ...
2017-05-01
Here, 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 e ects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a darkmore » 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, brie y commenting on the relevance of the allowed parameter space to low-energy anomalies in π0 and 8Be* decay.« less
NASA Astrophysics Data System (ADS)
Lu, F.; Liu, Z.; Zhang, S.; Jacob, R.
2017-04-01
The tropical bias of double-Intertropical Convergence Zone (ITCZ) has been a persistent feature in global climate models. It remains unclear how much of it is attributed to local and remote processes, respectively. Here we assess the extratropical influence on the tropical bias in a coupled general circulation model dynamically, systematically, and quantitatively using the Regional Coupled Data Assimilation (RCDA) method. RCDA experiments show that the model's double-ITCZ bias is improved systematically when sea surface temperature, air temperature, and wind are corrected toward real-world data from the extratropics into the tropics progressively. Quantitatively, the tropical asymmetry bias in precipitation and surface temperature is reduced by 40% due to extratropical impact from outside of 25°. Coupled dynamics, as well as atmospheric and oceanic processes, play important roles in this extratropical-to-tropical teleconnection. Energetic analysis of cross-equatorial atmospheric energy transport and equatorial net energy input are used to explain the changes in the precipitation bias.
Fluid flow up a spinning egg and the Coriolis force
NASA Astrophysics Data System (ADS)
Martinez, J. C.; Polatdemir, E.; Bansal, Ankita; Yifeng, Wang; Shengtao, Wang
2006-07-01
We study the dynamics of a spinning sphere whose south pole is in touch with the surface of a still body of liquid. When the sphere is turning fast enough, the fluid rises up the sphere, reaches the equator and is flung out as a fountain of droplets. Although the fountain forms for water a weakly viscous fluid, and for propylene glycol a much more viscous fluid, the dynamical situation is different for each. For flows at mid-latitudes on the sphere, we formulate the dynamical equations for the two liquids in terms of Newton's law in a rotating frame, noting that the Coriolis force plays an essential role in both liquids, and obtain qualitative agreement with observations. We also discuss the possible roles played by other forces.
Rapid PCR amplification of DNA utilizing Coriolis effects.
Mårtensson, Gustaf; Skote, Martin; Malmqvist, Mats; Falk, Mats; Asp, Allan; Svanvik, Nicke; Johansson, Arne
2006-08-01
A novel polymerase chain reaction (PCR) method is presented that utilizes Coriolis and centrifugal effects, produced by rotation of the sample disc, in order to increase internal circulatory rates, and with them temperature homogenization and mixing speeds. A proof of concept has been presented by testing a rapid 45-cycle PCR DNA amplification protocol. During the repeated heating and cooling that constitutes a PCR process, the 100 microL samples were rotated at a speed equivalent to an effective acceleration of gravity of 7,000 g. A cycle time of 20.5 s gave a total process time of 15 min to complete the 45 cycles. A theoretical and numerical analysis of the resulting flow, which describes the increased mixing and temperature homogenization, is presented. The device gives excellent reaction speed efficiency, which is beneficial for rapid PCR.
Coupled land surface/hydrologic/atmospheric models
NASA Technical Reports Server (NTRS)
Pielke, Roger; Steyaert, Lou; Arritt, Ray; Lahtakia, Mercedes; Smith, Chris; Ziegler, Conrad; Soong, Su Tzai; Avissar, Roni; Wetzel, Peter; Sellers, Piers
1993-01-01
The topics covered include the following: prototype land cover characteristics data base for the conterminous United States; surface evapotranspiration effects on cumulus convection and implications for mesoscale models; the use of complex treatment of surface hydrology and thermodynamics within a mesoscale model and some related issues; initialization of soil-water content for regional-scale atmospheric prediction models; impact of surface properties on dryline and MCS evolution; a numerical simulation of heavy precipitation over the complex topography of California; representing mesoscale fluxes induced by landscape discontinuities in global climate models; emphasizing the role of subgrid-scale heterogeneity in surface-air interaction; and problems with modeling and measuring biosphere-atmosphere exchanges of energy, water, and carbon on large scales.
Modelling of Slag Foaming Coupled with Decarburisation
NASA Astrophysics Data System (ADS)
Sattar, M. A.; Naser, J.; Brooks, G.
CFD models have been developed and numerical simulations have been carried out to predict the formation of foam in oxygen steelmaking. Foam was considered as a separate phase comprising a mixture of gas and liquid. Bubble break up and coalescence models have also been incorporated in a CFD model to predict the number density of individual bubble classes. A population balance equation was used to track the number density of each bubble class. Decarburization with heat generation from chemical reactions was integrated in the process. User subroutines were written in FORTRAN to incorporate the foam formation, the bubble break up and coalescence rate and decarburisation in the main program. The model predicted the foam height, bubble number density, velocity of phases, decarburization, and turbulence. The result from the model has been compared with available data from literature and found to be in reasonable agreement with the experimental and plant data.
Why the Coriolis force turns a wind farm wake to the right in the Northern Hemisphere
NASA Astrophysics Data System (ADS)
van der Laan, M. P.; Sørensen, N. N.
2016-09-01
The interaction between the Coriolis force and a wind farm wake is investigated by Reynolds-Averaged Navier-Stokes simulations, using two different wind farm representations: a high roughness and 5×5 actuator disks. Surprisingly, the calculated wind farm wake deflection is opposite in the two simulations. A momentum balance in the cross flow direction shows that the interaction between the Coriolis force and the 5 × 5 actuator disks is complex due to turbulent mixing of fresh momentum from above into the wind farm, which is not observed for the interaction between the Coriolis force and a roughness change.
The XY model coupled to two-dimensional quantum gravity
NASA Astrophysics Data System (ADS)
Baillie, C. F.; Johnston, D. A.
1992-09-01
We perform Monte Carlo simulations using the Wolff cluster algorithm of the XY model on both fixed and dynamical phi-cubed graphs (i.e. without and with coupling to two-dimensional quantum gravity). We compare the numerical results with the theoretical expectation that the phase transition remains of KT type when the XY model is coupled to gravity. We also examine whether the universality we discovered in our earlier work on various Potts models with the same value of the central charge, c, carries over to the XY model, which has c=1.
The Coupled Chemical and Physical Dynamics Model of MALDI
NASA Astrophysics Data System (ADS)
Knochenmuss, Richard
2016-06-01
The coupled physical and chemical dynamics model of ultraviolet matrix-assisted laser desorption/ionization (MALDI) has reproduced and explained a wide variety of MALDI phenomena. The rationale behind and elements of the model are reviewed, including the photophysics, kinetics, and thermodynamics of primary and secondary reaction steps. Experimental results are compared with model predictions to illustrate the foundations of the model, coupling of ablation and ionization, differences between and commonalities of matrices, secondary charge transfer reactions, ionization in both polarities, fluence and concentration dependencies, and suppression and enhancement effects.
Finite Element Modelling of Fluid Coupling in the Coiled Cochlea
NASA Astrophysics Data System (ADS)
Ni, Guangjian; Elliott, S. J.; Lineton, B.; Saba, R.
2011-11-01
A finite element model is first used to calculate the modal pressure difference for a box model of the cochlea, which shows that the number of fluid elements across the width of the cochlea determines the accuracy with which the near field, or short wavenumber, component of the fluid coupling is reproduced. Then results are compared with the analytic results to validate the accuracy of the FE model. It is, however, the far field, or long wavelength, component of the fluid coupling that is most affected by the geometry. A finite element model of the coiled cochlea is then used to calculate fluid coupling in this case, which has similar characteristics to the uncoiled model.
Modeling the dispersion in electromechanically coupled myocardium
Eriksson, Thomas S. E.; Prassl, Anton J.; Plank, Gernot; Holzapfel, Gerhard A.
2014-01-01
SUMMARY We present an approach to model the dispersion of fiber and sheet orientations in the myocardium. By utilizing structure parameters, an existing orthotropic and invariant-based constitutive model developed to describe the passive behavior of the myocardium is augmented. Two dispersion parameters are fitted to experimentally observed angular dispersion data of the myocardial tissue. Computations are performed on a unit myocardium tissue cube and on a slice of the left ventricle indicating that the dispersion parameter has an effect on the myocardial deformation and stress development. The use of fiber dispersions relating to a pathological myocardium had a rather big effect. The final example represents an ellipsoidal model of the left ventricle indicating the influence of fiber and sheet dispersions upon contraction over a cardiac cycle. Although only a minor shift in the pressure–volume (PV) loops between the cases with no dispersions and with fiber and sheet dispersions for a healthy myocardium was observed, a remarkably different behavior is obtained with a fiber dispersion relating to a diseased myocardium. In future simulations, this dispersion model for myocardial tissue may advantageously be used together with models of, for example, growth and remodeling of various cardiac diseases. PMID:23868817
ITG sideband coupling models for zonal flows
Stransky, M.
2011-05-15
Four-wave interaction model between ITG mode and zonal flow was derived using fluid equations. In this model, the zonal flow is excited non-linearly by ITG turbulence via Reynolds stress. Numerical simulations show that the system allows for a small range above the ITG threshold where the zonal flow can stabilize an unstable ITG mode, effectively increasing {eta}{sub i} threshold, an effect which has been called the Dimits shift. However, the shift is smaller than in known cases such that in the Cyclone base.
A coupled subsurface-boundary layer model of water on Mars
NASA Astrophysics Data System (ADS)
Zent, A. P.; Haberle, R. M.; Houben, H. C.; Jakosky, B. M.
1993-02-01
A 1D numerical model of the exchange of H2O between the atmosphere and subsurface of Mars through the PBL is employed to explore the mechanisms of H2O exchange and to elucidate the role played by the regolith in the local H2O budget. The atmospheric model includes effects of Coriolis, pressure gradient, and frictional forces for momentum: radiation, sensible heat flux, and advection for heat. It is suggested that in most cases, the flux through the Martian surface reverses twice in the course of each sol. The effects of surface albedo, thermal inertia, solar declination, atmospheric optical depth, and regolith pore structure are explored. It is proposed that higher thermal inertia forces more H2O into the atmosphere because the regolith is warmer at depth.
A multicomponent coupled model of glacier hydrology
NASA Astrophysics Data System (ADS)
Flowers, Gwenn Elizabeth
Multiple lines of evidence suggest a causal link between subglacial hydrology and phenomena such as fast-flowing ice. This evidence includes a measured correlation between water under alpine glaciers and their motion, the presence of saturated sediment beneath Antaxctic ice streams, and geologic signatures of enhanced paleo-ice flow over deformable substrates. The complexity of the glacier bed as a three-component mixture presents an obstacle to unraveling these conundra. Inadequate representations of hydrology, in part, prevent us from closing the gap between empirical descriptions and a comprehensive consistent framework for understanding the dynamics of glacierized systems. I have developed a distributed numerical model that solves equations governing glacier surface runoff, englacial water transport, subglacial drainage, and subsurface groundwater flow. Ablation and precipitation drive the surface model through a temperature-index parameterization. Water is permitted to flow over and off the glacier, or to the bed through a system of crevasses, pipes, and fractures. A macroporous sediment horizon transports subglacial water to the ice margin or to an underlying aquifer. Governing equations are derived from the law of mass conservation and are expressed as a balance between the internal redistribution of water and external sources. Each of the four model components is represented as a two-dimensional, vertically-integrated layer that communicates with its neighbors through water exchange. Stacked together, these layers approximate a three-dimensional system. I tailor the model to Trapridge Glacier, where digital maps of the surface and bed have been derived from ice-penetrating radar data. Observations of subglacial water pressure provide additional constraints on model parameters and a basis for comparison of simulations with real data. Three classical idealizations of glacier geometry are used for simple model experiments. Equilibrium tests emphasize geometric
Using a dyadic logistic multilevel model to analyze couple data.
Preciado, Mariana A; Krull, Jennifer L; Hicks, Andrew; Gipson, Jessica D
2016-02-01
There is growing recognition within the sexual and reproductive health field of the importance of incorporating both partners' perspectives when examining sexual and reproductive health behaviors. Yet, the analytical approaches to address couple data have not been readily integrated and utilized within the demographic and public health literature. This paper seeks to provide readers unfamiliar with analytical approaches to couple data an applied example of the use of dyadic logistic multilevel modeling, a useful approach to analyzing couple data to assess the individual, partner and couple characteristics that are related to individuals' reproductively relevant beliefs, attitudes and behaviors. The use of multilevel models in reproductive health research can help researchers develop a more comprehensive picture of the way in which individuals' reproductive health outcomes are situated in a larger relationship and cultural context.
Using a Dyadic Logistic Multilevel Model to Analyze Couple Data
Preciado, Mariana A.; Krull, Jennifer L.; Hicks, Andrew
2015-01-01
There is growing recognition within the sexual and reproductive health field of the importance of incorporating both partners’ perspectives when examining sexual and reproductive health behaviors. Yet, the analytical approaches to address couple data have not been readily integrated and utilized within the demographic and public health literature. This paper seeks to provide readers unfamiliar with analytical approaches to couple data an applied example of the use of dyadic logistic multilevel modeling, a useful approach to analyzing couple data to assess the individual, partner, and couple characteristics that are related to individuals’ reproductively relevant beliefs, attitudes, and behaviors. The use of multilevel models in reproductive health research can help researchers develop a more comprehensive picture of the way in which individuals’ reproductive health outcomes are situated in a larger relationship and cultural context. PMID:26363432
Revisiting vectorlike quark models with enhanced top Yukawa coupling
NASA Astrophysics Data System (ADS)
Hashimoto, Michio
2017-08-01
We revisit a scenario with an enhanced top Yukawa coupling in vectorlike quark (VLQ) models, where the top Yukawa coupling is larger than the standard model value and the lightest VLQ has a negative Yukawa coupling. We find that the parameter space satisfying the LHC bounds of the Higgs signal strengths consistently with the precision measurements is rather wide. Because the Lagrangian parameters of the Yukawa couplings are large, such scenario can be realized in some strongly interacting theories. It also turns out that there is a noticeable relation between the contributions of the triangle and box diagrams in the g g →h h process by using the lowest order of the 1 /M expansion where M is the heavy mass running in the loops.
Model coupling for multiphase flow in porous media
NASA Astrophysics Data System (ADS)
Helmig, Rainer; Flemisch, Bernd; Wolff, Markus; Ebigbo, Anozie; Class, Holger
2013-01-01
Numerical models for flow and transport in porous media are valid for a particular set of processes, scales, levels of simplification and abstraction, grids etc. The coupling of two or more specialised models is a method of increasing the overall range of validity while keeping the computational costs relatively low. Several coupling concepts are reviewed in this article with a focus on the authors’ work in this field. The concepts are divided into temporal and spatial coupling concepts, of which the latter is subdivided into multi-process, multi-scale, multi-dimensional, and multi-compartment coupling strategies. Examples of applications for which these concepts can be relevant include groundwater protection and remediation, carbon dioxide storage, nuclear-waste disposal, soil dry-out and evaporation processes as well as fuel cells and technical filters.
Testing coupled dark energy models with their cosmological background evolution
NASA Astrophysics Data System (ADS)
van de Bruck, Carsten; Mifsud, Jurgen; Morrice, Jack
2017-02-01
We consider a cosmology in which dark matter and a quintessence scalar field responsible for the acceleration of the Universe are allowed to interact. Allowing for both conformal and disformal couplings, we perform a global analysis of the constraints on our model using Hubble parameter measurements, baryon acoustic oscillation distance measurements, and a Supernovae Type Ia data set. We find that the additional disformal coupling relaxes the conformal coupling constraints. Moreover, we show that, at the background level, a disformal interaction within the dark sector is preferred to both Λ CDM and uncoupled quintessence, hence favoring interacting dark energy.
Strong Local-Nonlocal Coupling for Integrated Fracture Modeling
Littlewood, David John; Silling, Stewart A.; Mitchell, John A.; Seleson, Pablo D.; Bond, Stephen D.; Parks, Michael L.; Turner, Daniel Z.; Burnett, Damon J.; Ostien, Jakob; Gunzburger, Max
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
Coupled Facility-Payload Vibration Modeling Improvements
NASA Technical Reports Server (NTRS)
Carnahan, Timothy M.; Kaiser, Michael A.
2015-01-01
A major phase of aerospace hardware verification is vibration testing. The standard approach for such testing is to use a shaker to induce loads into the payload. In preparation for vibration testing at National Aeronautics and Space Administration/Goddard Space Flight Center an analysis is performed to assess the responses of the payload. A new method of modeling the test is presented that takes into account dynamic interactions between the facility and the payload. This dynamic interaction has affected testing in the past, but been ignored or adjusted for during testing. By modeling the combined dynamics of the facility and test article (payload) it is possible to improve the prediction of hardware responses. Many aerospace test facilities work in similar way to those at NASA/Goddard Space Flight Center. Lessons learned here should be applicable to other test facilities with similar setups.
Coupled Facility/Payload Vibration Modeling Improvements
NASA Technical Reports Server (NTRS)
Carnahan, Timothy M.; Kaiser, Michael
2015-01-01
A major phase of aerospace hardware verification is vibration testing. The standard approach for such testing is to use a shaker to induce loads into the payload. In preparation for vibration testing at NASA/GSFC there is an analysis to assess the responses of the payload. A new method of modeling the test is presented that takes into account dynamic interactions between the facility and the payload. This dynamic interaction has affected testing in the past, but been ignored or adjusted for during testing. By modeling the combination of the facility and test article (payload) it is possible to improve the prediction of hardware responses. Many aerospace test facilities work in similar way to those at NASA Goddard Space Flight Center. Lessons learned here should be applicable to other test facilities with similar setups.
The Kac Model Coupled to a Thermostat
NASA Astrophysics Data System (ADS)
Bonetto, Federico; Loss, Michael; Vaidyanathan, Ranjini
2014-08-01
In this paper we study a model of randomly colliding particles interacting with a thermal bath. Collisions between particles are modeled via the Kac master equation while the thermostat is seen as an infinite gas at thermal equilibrium at inverse temperature . The system admits the canonical distribution at inverse temperature as the unique equilibrium state. We prove that any initial distribution approaches the equilibrium distribution exponentially fast both by computing the gap of the generator of the evolution, in a proper function space, as well as by proving exponential decay in relative entropy. We also show that the evolution propagates chaos and that the one particle marginal, in the large system limit, satisfies an effective Boltzmann-type equation.
Service-Oriented Approach to Coupling Earth System Models and Modeling Frameworks
NASA Astrophysics Data System (ADS)
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.
The effect of the Coriolis force on the stability of rotating magnetic stars
NASA Technical Reports Server (NTRS)
Sakurai, K.
1972-01-01
The effect of the Coriolis force on the stability of rotating magnetic stars in hydrostatic equilibrium is investigated by using the method of the energy principle. It is shown that this effect is to inhibit the onset of instability.
The effect of the Coriolis force on the stability of rotating magnetic stars.
NASA Technical Reports Server (NTRS)
Sakurai, K.
1972-01-01
The effect of the Coriolis force on the stability of rotating magnetic stars in hydrostatic equilibrium is investigated by using the method of the energy principle. It is shown that this effect is to inhibit the onset of instability.
Coupling TOUGH2 with CLM3: Developing a Coupled Land Surface andSubsurface Model
Pan, Lehua; Jin, Jiming; Miller, Norman; Wu, Yu-Shu; Bodvarsson,Gudmundur
2006-05-19
An understanding of the hydrologic interactions among atmosphere, land surface, and subsurface is one of the keys to understanding the water cycling system that supports life on earth. The inherent coupled processes and complex feedback structures among subsystems make such interactions difficult to simulate. In this paper, we present a model that simulates the land surface and subsurface hydrologic response to meteorological forcing. This model combines a state-of-the-art land-surface model, the NCAR Community Land Model version 3 (CLM3), with a variably saturated groundwater model, TOUGH2, through an internal interface that includes flux and state variables shared by the two submodels. Specifically, TOUGH2 uses infiltration, evaporation, and root-uptake rates, calculated by CLM3, as source/sink terms in its simulation; CLM3 uses saturation and capillary pressure profiles, calculated by TOUGH2, as state variables in its simulation. This new model, CLMT2, preserves the best aspects of both submodels: the state-of-the-art modeling capability of surface energy and hydrologic processes (including snow, runoff, freezing/melting, evapotranspiration, radiation, and biophysiological processes) from CLM3 and the more realistic physical-process-based modeling capability of subsurface hydrologic processes (including heterogeneity, three-dimensional flow, seamless combining of unsaturated and saturated zone, and water table) from TOUGH2. The preliminary simulation results show that the coupled model greatly improved the predictions of the groundwater table, evapotranspiration, and surface temperature at a real watershed, as evaluated using 18 years of observed data. The new model is also ready to be coupled with an atmospheric simulation model, to form one of the first top of the atmosphere to deep groundwater atmosphere-land-surface-subsurface models.
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...
FULLY COUPLED "ONLINE" CHEMISTRY WITHIN THE WRF MODEL
A fully coupled "online" Weather Research and Forecasting/Chemistry (WRF/Chem) model has been developed. The air quality component of the model is fully consistent with the meteorological component; both components use the same transport scheme (mass and scalar preserving), the s...
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...
FULLY COUPLED "ONLINE" CHEMISTRY WITHIN THE WRF MODEL
A fully coupled "online" Weather Research and Forecasting/Chemistry (WRF/Chem) model has been developed. The air quality component of the model is fully consistent with the meteorological component; both components use the same transport scheme (mass and scalar preserving), the s...
Improving data transfer for model coupling
NASA Astrophysics Data System (ADS)
Zhang, C.; Liu, L.; Yang, G.; Li, R.; Wang, B.
2015-10-01
Data transfer, which means transferring data fields between two component models or rearranging data fields among processes of the same component model, is a fundamental operation of a coupler. Most of state-of-the-art coupler versions currently use an implementation based on the point-to-point (P2P) communication of the Message Passing Interface (MPI) (call such an implementation "P2P implementation" for short). In this paper, we reveal the drawbacks of the P2P implementation, including low communication bandwidth due to small message size, variable and big number of MPI messages, and jams during communication. To overcome these drawbacks, we propose a butterfly implementation for data transfer. Although the butterfly implementation can outperform the P2P implementation in many cases, it degrades the performance in some cases because the total message size transferred by the butterfly implementation is larger than that by the P2P implementation. To make the data transfer completely improved, we design and implement an adaptive data transfer library that combines the advantages of both butterfly implementation and P2P implementation. Performance evaluation shows that the adaptive data transfer library significantly improves the performance of data transfer in most cases and does not decrease the performance in any cases. Now the adaptive data transfer library is open to the public and has been imported into a coupler version C-Coupler1 for performance improvement of data transfer. We believe that it can also improve other coupler versions.
Concepts and models of coupled systems
NASA Astrophysics Data System (ADS)
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.
NASA Technical Reports Server (NTRS)
Hickey, M. P.
1988-01-01
The chemical-dynamical model of Walterscheid et al. (1987), which describes wave-driven fluctuations in OH nightglow, was modified to include the effects of both eddy thermal conduction and viscosity, as well as the Coriolis force (with the shallow atmosphere approximation). Using the new model, calculations were performed for the same nominal case as used by Walterscheid et al. but with only wave periods considered. For this case, the Coriolis force was found to be unimportant at any wave period. For wave periods greater than 2 or 3 hours, the inclusion of thermal conduction alone greatly modified the results (in terms of a complex ratio 'eta' which expresses the relationship between the intensity oscillation about the time-averaged intensity and the temperature oscillation about the time-averaged temperature); this effect was reduced with the further inclusion of the eddy viscosity.
Preliminary investigation of models of coupled clocks and coupled driven pendulums
NASA Astrophysics Data System (ADS)
LeBailly, Christopher A.
In this paper we study a phenomena observed in the 17 th century by Christiaan Huygens. He found that two pendulum clocks placed on a common support synchronized over time. We study a model of this type of coupling primarily using the fourth-order Runge-Kutta method. We look at time series to get a picture of what types of synchronization occur and then once we figure out how to classify synchronization we study how varying the damping in the system affects the synchronization. We next look at what happens when driven pendulums replace the clocks. We compare phase portraits and bifurcation diagrams of the uncoupled driven pendulum to the coupled driven pendulums to get a picture of how the dynamics and chaotic tendencies of the driven pendulum change with the coupling.
Analysis of the Coriolis Interaction between nu(6) and nu(8) Bands of HCOOH.
Tan; Goh; Ong; Teo
2000-08-01
The Fourier transform infrared (FTIR) spectrum of the nu(6) band of formic acid (HCOOH) has been recorded with a resolution of 0.0024 cm(-1) in the spectral range 1050-1160 cm(-1). The nu(6) band was found to be strongly perturbed by the nearby nu(8) band centered at about 1033.5 cm(-1). Using a Watson's A-reduced Hamiltonian in the I(r) representation, and with the inclusion of a-type Coriolis coupling constant, a simultaneous fit of nu(6) and nu(8) was performed. A total of 2485 infrared transitions including about 700 perturbed transitions of nu(6) and 19 transitions of nu(8) was fitted with an rms uncertainty of 0.0006 cm(-1). Accurate rovibrational constants up to sextic order for both nu(6) and nu(8) were obtained. The nu(6) band was analyzed to be a type AB hybrid with a band center at 1104.852109 +/- 0.000050 cm(-1). The band center for nu(8) was found to be 1033.4647 +/- 0.0021 cm(-1). Copyright 2000 Academic Press.
Dynamic Coupling of Alaska Based Ecosystem and Geophysical Models into an Integrated Model
NASA Astrophysics Data System (ADS)
Bennett, A.; Carman, T. B.
2012-12-01
As scientific models and the challenges they address have grown in complexity and scope, so has interest in dynamically coupling or integrating these models. Dynamic model coupling presents software engineering challenges stemming from differences in model architectures, differences in development styles between modeling groups, and memory and run time performance concerns. The Alaska Integrated Ecosystem Modeling (AIEM) project aims to dynamically couple three independently developed scientific models so that each model can exchange run-time data with each of the other models. The models being coupled are a stochastic fire dynamics model (ALFRESCO), a permafrost model (GIPL), and a soil and vegetation model (DVM-DOS-TEM). The scientific research objectives of the AIEM project are to: 1) use the coupled models for increasing our understanding of climate change and other stressors on landscape level physical and ecosystem processes, and; 2) provide support for resource conservation planning and decision making. The objectives related to the computer models themselves are modifiability, maintainability, and performance of the coupled and individual models. Modifiability and maintainability are especially important in a research context because source codes must be continually adapted to address new scientific concepts. Performance is crucial to delivering results in a timely manner. To achieve the objectives while addressing the challenges in dynamic model coupling, we have designed an architecture that emphasizes high cohesion for each individual model and loose coupling between the models. Each model will retain the ability to run independently, or to be available as a linked library to the coupled model. Performance is facilitated by parallelism in the spatial dimension. With close collaboration among modeling groups, the methodology described here has demonstrated the feasibility of coupling complex ecological and geophysical models to provide managers with more
An efficient model for coupling structural vibrations with acoustic radiation
NASA Astrophysics Data System (ADS)
Frendi, A.; Maestrello, L.; Ting, L.
1995-05-01
In this paper, the problem of coupling between panel vibration and near and far field acoustic radiation is studied. The panel vibration is governed by the non-linear plate equations while the loading on the panel, which is the pressure difference across the panel, depends on the reflected and transmitted waves. Two models are used to solve this structural-acoustic interaction problem. One solves the three-dimensional non-linear Euler equations for the acoustic field coupled with the non-linear plate equations (the fully coupled model). The second uses the linear wave equation for the acoustic field and expresses the load as a double integral involving the panel oscillation (the decoupled model). The panel oscillation governed by a system of integro-differential equations is solved numerically and the acoustic field is then defined by an explicit formula. Numerical results are obtained using the two models for linear and non-linear panel vibration regimes excited by incident waves having different sound pressure levels. The predictions given by these two models are in good agreement, but the computational time needed for the "fully coupled model" is 60 times longer than that for "the decoupled model".
Analytic Thermoelectric Couple Modeling: Variable Material Properties and Transient Operation
NASA Technical Reports Server (NTRS)
Mackey, Jonathan A.; Sehirlioglu, Alp; Dynys, Fred
2015-01-01
To gain a deeper understanding of the operation of a thermoelectric couple a set of analytic solutions have been derived for a variable material property couple and a transient couple. Using an analytic approach, as opposed to commonly used numerical techniques, results in a set of useful design guidelines. These guidelines can serve as useful starting conditions for further numerical studies, or can serve as design rules for lab built couples. The analytic modeling considers two cases and accounts for 1) material properties which vary with temperature and 2) transient operation of a couple. The variable material property case was handled by means of an asymptotic expansion, which allows for insight into the influence of temperature dependence on different material properties. The variable property work demonstrated the important fact that materials with identical average Figure of Merits can lead to different conversion efficiencies due to temperature dependence of the properties. The transient couple was investigated through a Greens function approach; several transient boundary conditions were investigated. The transient work introduces several new design considerations which are not captured by the classic steady state analysis. The work helps to assist in designing couples for optimal performance, and also helps assist in material selection.
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.
PDF turbulence modeling and DNS
NASA Technical Reports Server (NTRS)
Hsu, A. T.
1992-01-01
The problem of time discontinuity (or jump condition) in the coalescence/dispersion (C/D) mixing model is addressed in probability density function (pdf). A C/D mixing model continuous in time is introduced. With the continuous mixing model, the process of chemical reaction can be fully coupled with mixing. In the case of homogeneous turbulence decay, the new model predicts a pdf very close to a Gaussian distribution, with finite higher moments also close to that of a Gaussian distribution. Results from the continuous mixing model are compared with both experimental data and numerical results from conventional C/D models. The effect of Coriolis forces on compressible homogeneous turbulence is studied using direct numerical simulation (DNS). The numerical method used in this study is an eight order compact difference scheme. Contrary to the conclusions reached by previous DNS studies on incompressible isotropic turbulence, the present results show that the Coriolis force increases the dissipation rate of turbulent kinetic energy, and that anisotropy develops as the Coriolis force increases. The Taylor-Proudman theory does apply since the derivatives in the direction of the rotation axis vanishes rapidly. A closer analysis reveals that the dissipation rate of the incompressible component of the turbulent kinetic energy indeed decreases with a higher rotation rate, consistent with incompressible flow simulations (Bardina), while the dissipation rate of the compressible part increases; the net gain is positive. Inertial waves are observed in the simulation results.
Perceptual disturbances predicted in zero-g through three-dimensional modeling.
Holly, Jan E
2003-01-01
Perceptual disturbances in zero-g and 1-g differ. For example, the vestibular coriolis (or "cross-coupled") effect is weaker in zero-g. In 1-g, blindfolded subjects rotating on-axis experience perceptual disturbances upon head tilt, but the effects diminish in zero-g. Head tilts during centrifugation in zero-g and 1-g are investigated here by means of three-dimensional modeling, using a model that was previously used to explain the zero-g reduction of the on-axis vestibular coriolis effect. The model's foundation comprises the laws of physics, including linear-angular interactions in three dimensions. Addressed is the question: In zero-g, will the vestibular coriolis effect be as weak during centrifugation as during on-axis rotation? Centrifugation in 1-g was simulated first, with the subject supine, head toward center. The most noticeable result concerned direction of head yaw. For clockwise centrifuge rotation, greater perceptual effects arose in simulations during yaw counterclockwise (as viewed from the top of the head) than for yaw clockwise. Centrifugation in zero-g was then simulated with the same "supine" orientation. The result: In zero-g the simulated vestibular coriolis effect was greater during centrifugation than during on-axis rotation. In addition, clockwise-counterclockwise differences did not appear in zero-g, in contrast to the differences that appear in 1-g.
Hennion, P Y; Mollard, R
1993-01-01
Under conditions of prolonged space flight, it may be feasible to restore gravity artificially using centrifugal inertial forces in a spinning vehicle. As a result, the motion of the passengers relative to the vehicle is affected by Coriolis forces. The aim of this study is to propose a theoretical method to evaluate the extent of these effects compared to other inertial or motor forces affecting movement. We investigated typical right upper limb movement in a numerical model with a two-solid-links mechanism, including a spherical joint for the shoulder and a hinge joint for the elbow. The inertial and dimensional characteristics of this model derive from measurements and computations obtained on laboratory subjects. The same is true for the movements assigned to the model. These were inferred from actual recordings of arm movement when the subject presses a button placed in front of him with his index finger. From these relative velocities, the resulting forces and moments applied to the elbow and the shoulder were computed for a 1 rad s-1 rotational speed of transport motion, using classical kinetic relations. The result is that the Coriolis moments are of the same order of magnitude as the corresponding inertial moments and one-tenth of the value of a typical elbow flexion moment. Thus, they should cause a significant disturbance in movement.
Integrative Systems Models of Cardiac Excitation Contraction Coupling
Greenstein, Joseph L.; Winslow, Raimond L.
2010-01-01
Excitation-contraction coupling in the cardiac myocyte is mediated by a number of highly integrated mechanisms of intracellular Ca2+ transport. The complexity and integrative nature of heart cell electrophysiology and Ca2+-cycling has led to an evolution of computational models that have played a crucial role in shaping our understanding of heart function. An important emerging theme in systems biology is that the detailed nature of local signaling events, such as those that occur in the cardiac dyad, have important consequences at higher biological scales. Multi-scale modeling techniques have revealed many mechanistic links between micro-scale events, such as Ca2+ binding to a channel protein, and macro-scale phenomena, such as excitation-contraction coupling gain. Here we review experimentally based multi-scale computational models of excitation-contraction coupling and the insights that have been gained through their application. PMID:21212390
A New Look at the Physics of Rossby Waves: A Mechanical-Coriolis Oscillation
NASA Astrophysics Data System (ADS)
Cai, M.; Huang, B.
2012-12-01
The presence of the latitudinal variation of the Coriolis parameter serves as a mechanical barrier that causes a mass convergence for the poleward geostrophic flow and divergence for the equatorward flow, just as a sloped bottom terrain does to a crossover flow. Part of the mass convergence causes pressure to rise along the uphill pathway while the remaining part is detoured to cross isobars out of the pathway. This mechanically excited cross-isobar flow, being unbalanced geostrophically, is subject to a "half-cycle" Coriolis force that only turns it to the direction parallel to isobars without continuing to turn it further back to its opposite direction because the geostrophic balance is reestablished once the flow becomes parallel to isobars. Such oscillation, involving a barrier-induced mass convergence, a mechanical deflection, and a half-cycle Coriolis deflection, is referred to as a mechanical-Coriolis oscillation with a "barrier-induced half-cycle Coriolis force" as its restoring force. Through a complete cycle of the mechanical-Coriolis oscillation, a new geostrophically balanced flow pattern emerges to the left of the existing flow when facing the uphill (downhill) direction of the barrier in the North (Southern) Hemisphere. The β-barrier is always sloped towards the pole in both hemispheres, responsible for the westward propagation of Rossby waves.
Numerical analysis of Coriolis effect on low-head hydraulic turbines
NASA Astrophysics Data System (ADS)
Ahn, S. H.; Xiao, Y. X.; Zhou, X. Z.; Zhang, J.; Zeng, C. J.; Luo, Y. Y.; Xu, W.; Wang, Z. W.
2016-11-01
For the low-head hydropower station, the operating head is low, and the turbine intake channel is relatively short. The turbine internal flow behaviour can be influenced by fluid flows in the upstream reservoir easily, then it would influence the turbine hydraulic performance. Water flows in the upstream reservoir can be influenced by the Coriolis force by the Earth rotation, and it differs at the different Rossby number. In this paper, the Coriolis effect on the approach flows and the turbine performances are investigated numerically for the low-head units. Firstly, the Coriolis effect (under the different latitudes and the same characteristic length scale) on reservoir flows was predicted. Secondly, the prototype performance of a bulb-type turbine was simulated including the reservoir flow with the Coriolis effect, and then the effect on the turbine performance is be discussed. Results show that the flow field in the upstream reservoir at the low Rossby number, the ratio of inertial force to Coriolis force, can sufficiently influence the turbine intake flows and the turbine performances. Adjusting the side-wall distance can reduce the Coriolis effects.
A Coupled Aeroelastic Model for Launch Vehicle Stability Analysis
NASA Technical Reports Server (NTRS)
Orr, Jeb S.
2010-01-01
A technique for incorporating distributed aerodynamic normal forces and aeroelastic coupling effects into a stability analysis model of a launch vehicle is presented. The formulation augments the linear state-space launch vehicle plant dynamics that are compactly derived as a system of coupled linear differential equations representing small angular and translational perturbations of the rigid body, nozzle, and sloshing propellant coupled with normal vibration of a set of orthogonal modes. The interaction of generalized forces due to aeroelastic coupling and thrust can be expressed as a set of augmenting non-diagonal stiffness and damping matrices in modal coordinates with no penalty on system order. While the eigenvalues of the structural response in the presence of thrust and aeroelastic forcing can be predicted at a given flight condition independent of the remaining degrees of freedom, the coupled model provides confidence in closed-loop stability in the presence of rigid-body, slosh, and actuator dynamics. Simulation results are presented that characterize the coupled dynamic response of the Ares I launch vehicle and the impact of aeroelasticity on control system stability margins.
Development of a coupled pathogen-hydrologic catchment model
NASA Astrophysics Data System (ADS)
Haydon, S.; Deletic, A.
2006-09-01
SummaryLarge numbers of pathogens can be mobilised from drinking water catchments during wet weather causing serious problems in management of water treatment plants. This paper presents an attempt to model pathogen discharges from large catchments. Two conceptual continuous pathogen models have been developed and evaluated using E. coli as a pathogen indicator. The first model, the EG model, describes surface and subsurface pathogen transport processes by means of wash-off and loss equations. It is coupled to an existing hydrologic model (SimHyd) that predicts flows. The second model, named ASP, takes into account only surface pathogen transport processes. It is coupled to a stormflow-baseflow separation model, and therefore is simpler than EG. The models have been tested against baseflow and storm event E. coli concentrations measured at three dissimilar catchments from southern Australia. The prediction of pathogen peak concentrations by the EG model was reasonably good; the coefficient of correlation between the measured and modelled pathogen peaks for all three catchments was r2 = 0.93. However, the ASP model was not able to model the peaks well ( r2 = 0.54). The prediction of pathogen loads was significantly better with r2 = 0.95 for the EG model and r2 = 0.89 for the ASP model. It was concluded that a slightly more complex EG model was performing better than the oversimplified ASP model.
Validation of coupled atmosphere-fire behavior models
Bossert, J.E.; Reisner, J.M.; Linn, R.R.; Winterkamp, J.L.; Schaub, R.; Riggan, P.J.
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.
Critical region for an Ising model coupled to causal triangulations
NASA Astrophysics Data System (ADS)
Cerda-Hernández, J.
2017-02-01
This paper extends the results obtained by Hernández et al for the annealed Ising model coupled to two-dimensional causal dynamical triangulations. We employ the Fortuin‑Kasteleyn (FK) representation in order to determine a region in the quadrant of the parameters β,μ >0 where the critical curve for the annealed model is possibly located. This can be done by outlining a region where the model has a unique infinite-volume Gibbs measure, and a region where the finite-volume Gibbs measure does not have weak limit (in fact, does not exist if the volume is large enough). We also improve the region where the model has a one dimensional geometry with respect to the unique weak limit measure, which implies that the Ising model on causal triangulation does not have phase transition in this region. Furthermore, we provide a better approximation of the free energy for the coupled model.
A coupled bubble plume-reservoir model for hypolimnetic oxygenation
NASA Astrophysics Data System (ADS)
Singleton, V. L.; Rueda, F. J.; Little, J. C.
2010-12-01
A model for a linear bubble plume used for hypolimnetic oxygenation was coupled with a three-dimensional hydrodynamic model to simulate the complex interaction between bubble plumes and the large-scale processes of transport and mixing. The coupled model accurately simulated the evolution of dissolved oxygen (DO) and temperature fields that occurred during two full-scale diffuser tests in a water supply reservoir. The prediction of asymmetric circulation cells laterally and longitudinally on both sides of the linear diffuser was due to the uneven reservoir bathymetry. Simulation of diffuser operation resulted in baroclinic pressure gradients, which caused vertical oscillations above the hypolimnion and contributed to distribution of plume detrainment upstream and downstream of the diffuser. On the basis of a first-order variance analysis, the largest source of uncertainty for both predicted DO and temperature was the model bathymetry, which accounted for about 90% of the overall uncertainty. Because the oxygen addition rate was 4 times the sediment oxygen uptake (SOU) rate, DO predictions were not sensitive to SOU. In addition to bathymetry, the momentum assigned to plume entrainment and detrainment is a significant source of uncertainty in the coupled model structure and appreciably affects the predicted intensity of mixing and lake circulation. For baseline runs, the entrainment and detrainment velocities were assumed to be half of the velocities through the flux face of the grid cells. Additional research on appropriate values of the plume detrainment momentum for the coupled model is required.
Strong coupling phase transitions in supersymmetric grand unified models
NASA Astrophysics Data System (ADS)
Reiss, David B.
1985-08-01
The determination of the temperature at which a grand unified model becomes strongly coupled should be based upon a physical quantity such as the screening lenght rather than the ad hoc condition that the opening becomes O(1). I use a recent calculation of this screening length (the inverse electric mass) to discuss some aspects of strong coupling behavior in the cosmology of supersymmetric grand unified models. Significant effects may occur in a variety of cases. An interesting possibilit is that there may be a pair of confining and deconfining phase transitions at a temperature as low as the supersymmetry breaking scale (O(TeV)). I present illustrative examples for these effects.
The Venus-Earth-Jupiter spin-orbit coupling model
NASA Astrophysics Data System (ADS)
Wilson, I. R. G.
2013-12-01
A Venus-Earth-Jupiter spin-orbit coupling model is constructed from a combination of the Venus-Earth-Jupiter tidal-torquing model and the gear effect. The new model produces net tangential torques that act upon the outer convective layers of the Sun with periodicities that match many of the long-term cycles that are found in the 10Be and 14C proxy records of solar activity.
String coupling and interactions in type IIB matrix model
Kitazawa, Yoshihisa; Nagaoka, Satoshi
2009-05-15
We investigate the interactions of closed strings in a IIB matrix model. The basic interaction of the closed superstring is realized by the recombination of two intersecting strings. Such interaction is investigated in a IIB matrix model via two-dimensional noncommutative gauge theory in the IR limit. By estimating the probability of the recombination, we identify the string coupling g{sub s} in the IIB matrix model. We confirm that our identification is consistent with matrix string theory.
A Fully Coupled Model for Electromechanics of the Heart
Xia, Henian; Wong, Kwai; Zhao, Xiaopeng
2012-01-01
We present a fully coupled electromechanical model of the heart. The model integrates cardiac electrophysiology and cardiac mechanics through excitation-induced contraction and deformation-induced current. Numerical schemes based on finite element were implemented in a supercomputer. Numerical examples were presented using a thin cardiac tissue and a dog ventricle with realistic geometry. Performance of the parallel simulation scheme was studied. The model provides a useful tool to understand cardiovascular dynamics. PMID:23118801
Midsummer Drought Pattern simulated by a coupled regional climate model
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Gabona, M. G.; Tan, T. L.
2014-05-01
The high resolution Fourier transform infrared (FTIR) absorption spectrum of the ν2 + ν12 band of cis-C2H2D2 was recorded in the frequency range of 2515-2960 cm-1 with an unapodized resolution of 0.0063 cm-1. This band was perturbed through c-type Coriolis interaction by the unobserved ν2 + 2ν10 band approximately 19 cm-1 below ν2 + ν12. A total of 751 unperturbed and perturbed infrared transitions of ν2 + ν12 were assigned and fitted using Watson's A-reduced Hamiltonian in the Ir representation with the inclusion of c-type Coriolis terms to give 11 rovibrational constants for the upper state (ν2 = 1, ν12 = 1) with improved accuracy. The ν2 + ν12A-type band is centred at 2898.8975 ± 0.0004 cm-1. From the Coriolis interaction analysis between the ν2 + ν12 and ν2 + 2ν10 bands of cis-C2H2D2, a higher order K-dependent c-type Coriolis coupling constant between the two bands was derived for the first time. Furthermore, rotational constants for the ν2 + 2ν10 band of cis-C2H2D2 centred at 2880.17 ± 0.06 cm-1 were also determined.
A Coupled Plasma and Sheath Model for High Density Reactors
NASA Technical Reports Server (NTRS)
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.
Comparison between MAVEN measurements and HELIOSARES coupled models
NASA Astrophysics Data System (ADS)
Leblanc, F.; Modolo, R.; Chaufray, J. Y.; Leclercq, L.; Curry, S.; Luhmann, J. G.; Lillis, R. J.; Hara, T.; McFadden, J. P.; Halekas, J. S.; Schneider, N. M.; Deighan, J.; Jakosky, B. M.
2016-12-01
Mars' MAVEN first measurements have clearly shown that heavy ion precipitation occur. One of the goals of MAVEN mission is to identify the different effects of this precipitation on Mars' atmosphere. In order to look for such effects, we will present a comparison between MAVEN observations and the results of modelling done by the HELIOSARES set of coupled models which describe the magnetosphere (hybrid magnetospheric model, LATHYS), the exosphere (Monte Carlo Exospheric General Model) and the atmosphere (LMD-GCM model). In particular, MAVEN provides the unique opportunity to couple observations of precipitation (STATIC, SWIA measurements) with observations of the exosphere (IUVS). In this work, we will present the comparison between these observations and HELIOSARES simulations and will show what can be deduced from the observations thanks to such comparison.
An investigation of helicopter dynamic coupling using an analytical model
NASA Technical Reports Server (NTRS)
Keller, Jeffrey D.
1995-01-01
Many attempts have been made in recent years to predict the off-axis response of a helicopter to control inputs, and most have had little success. Since physical insight is limited by the complexity of numerical simulation models, this paper examines the off-axis response problem using an analytical model, with the goal of understanding the mechanics of the coupling. A new induced velocity model is extended to include the effects of wake distortion from pitch rate. It is shown that the inclusion of these results in a significant change in the lateral flap response to a steady pitch rate. The proposed inflow model is coupled with the full rotor/body dynamics, and comparisons are made between the model and flight test data for a UH-60 in hover. Results show that inclusion of induced velocity variations due to shaft rate improves correlation in the pitch response to lateral cycle inputs.
Bose-Hubbard models coupled to cavity light fields
Silver, A. O.; Bhaseen, M. J.; Simons, B. D.; Hohenadler, M.
2010-02-15
Recent experiments on strongly coupled cavity quantum electrodynamics present new directions in ''matter-light'' systems. Following on from our previous work [Phys. Rev. Lett. 102, 135301 (2009)] we investigate Bose-Hubbard models coupled to a cavity light field. We discuss the emergence of photoexcitations or 'polaritons' within the Mott phase, and obtain the complete variational phase diagram. Exploiting connections to the super-radiance transition in the Dicke model we discuss the nature of polariton condensation within this novel state. Incorporating the effects of carrier superfluidity, we identify a first-order transition between the super-radiant Mott phase and the single component atomic superfluid. The overall predictions of mean field theory are in excellent agreement with exact diagonalization and we provide details of superfluid fractions, density fluctuations, and finite size effects. We highlight connections to recent work on coupled cavity arrays.
Solar system constraints on planetary Coriolis-type effects induced by rotation of distant masses
Iorio, Lorenzo
2010-08-01
We phenomenologically put local constraints on the rotation of distant masses by using the planets of the solar system. First, we analytically compute the orbital secular precessions induced on the motion of a test particle about a massive primary by a Coriolis-like force, treated as a small perturbation, in the case of a constant angular velocity vector Ψ directed along a generic direction in space. The semimajor axis a and the eccentricity e of the test particle do not secularly change, contrary to the inclination I, the longitude of the ascending node Ω, the longitude of the pericenter varpi and the mean anomaly M. Then, we compare our prediction for (dot varpi) with the corrections Δdot varpi to the usual perihelion precessions of the inner planets recently estimated by fitting long data sets with different versions of the EPM ephemerides. We obtain as preliminary upper bounds |Ψ{sub z}| ≤ 0.0006−0.013 arcsec cty{sup −1}, |Ψ{sub x}| ≤ 0.1−2.7 arcsec cty{sup −1}, |Ψ{sub y}| ≤ 0.3−2.3 arcsec cty{sup −1}. Interpreted in terms of models of space-time involving cosmic rotation, our results are able to yield constraints on cosmological parameters like the cosmological constant Λ and the Hubble parameter H{sub 0} not too far from their values determined with cosmological observations and, in some cases, several orders of magnitude better than the constraints usually obtained so far from space-time models not involving rotation. In the case of the rotation of the solar system throughout the Galaxy, occurring clockwise about the North Galactic Pole, our results for Ψ{sub z} are in disagreement with the expected value of it at more than 3−σ level. Modeling the Oort cloud as an Einstein-Thirring slowly rotating massive shell inducing Coriolis-type forces inside yields unphysical results for its putative rotation.
Drift-Scale Coupled Processes (DST and THC Seepage) Models
E. Gonnenthal; N. Spyoher
2001-02-05
The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000 [153447]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M and O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. 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 chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: (1) Performance Assessment (PA); (2) Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); (3) UZ Flow and Transport Process Model Report (PMR); and (4) Near-Field Environment (NFE) PMR. The work scope for this activity is presented in the TWPs cited above, and summarized as follows: continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in
Drift-Scale Coupled Processes (DST and THC Seepage) Models
E. Sonnenthale
2001-04-16
The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M&O) 2000 [1534471]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M&O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. 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 chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: Performance Assessment (PA); Near-Field Environment (NFE) PMR; Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); and UZ Flow and Transport Process Model Report (PMR). The work scope for this activity is presented in the TWPs cited above, and summarized as follows: Continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in this AMR are required
A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas
Munafò, A. Alfuhaid, S. A. Panesi, M.; Cambier, J.-L.
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.
Modelling the Auroral Magnetosphere-Ionosphere Coupling System at Jupiter
NASA Astrophysics Data System (ADS)
Bunce, E. J.; Cowley, S.; Provan, G.
2016-12-01
The magnetosphere-ionosphere coupling system at Jupiter is a topic of central significance in understanding the fundamental properties of its large-scale plasma environment. Theoretical discussion of this topic typically considers the properties of the field-aligned current systems that form part of a large-scale magnetosphere-ionosphere coupling current system associated with momentum exchange between the ionosphere and the magnetosphere, communicated via the magnetic field. The current system associated with the main oval is believed to be related to centrifugally-driven outward radial transport of iogenic plasma that leads to sub-corotation in the middle magnetosphere. In addition to the magnetosphere-ionosphere coupling current system, upward-directed field-aligned currents may flow at the open-closed field line boundary due to the shear between outer closed field lines and open field lines, which may relate to emission poleward of the main oval. An axi-symmetric model of the plasma flow in the jovian system, the related coupling currents, and the consequent auroral precipitation based on these combined ideas was initially devised to represent typical steady-state conditions for the system and later extended to consider auroral effects resulting from sudden compressions of the magnetosphere. More recently, the model has been extended along model magnetic field lines into the magnetosphere in order to relate them to in situ observations from the NASA Juno spacecraft at Jupiter. The field-aligned coupling currents associated with the modelled current systems produce a readily-observable azimuthal field signature that bends the field lines out of magnetic meridians. Here we show the computed azimuthal fields produced by our model auroral current system throughout the region between the ionosphere and the magnetic equator, and illustrate the results by evaluation of various model parameters (e.g. field-aligned current density, accelerating voltages, accelerated
A global model of electromagnetic coupling for nutations
NASA Astrophysics Data System (ADS)
Dumberry, Mathieu; Koot, Laurence
2012-09-01
Nutations are small variations in the orientation of the Earth's rotation axis in space. They are caused by the gravitational torque that the Moon, the Sun, and other planets exert on the equatorial bulge. As nutations involve differential rotations between the mantle, fluid core and inner core, the motion of each of these internal regions depends on the coupling between them. In particular, a coupling of a dissipative nature is required to match observations. One possibility is electromagnetic (EM) coupling at the inner and outer core boundaries, the focus of our study. Existing EM coupling models are based on a formulation where the perturbation variables and the equations they must satisfy are defined at local geographic points on the boundary. Here, we show how EM coupling models can be cast under a global formalism, where all variables are expanded in spherical harmonics. This formulation allows a separation of the contribution from the poloidal and toroidal parts of the EM torque, and we show that, under certain conductivity scenarios, this separation is important.
A computational fluid dynamics model of viscous coupling of hairs.
Lewin, Gregory C; Hallam, John
2010-06-01
Arrays of arthropod filiform hairs form highly sensitive mechanoreceptor systems capable of detecting minute air disturbances, and it is unclear to what extent individual hairs interact with one another within sensor arrays. We present a computational fluid dynamics model for one or more hairs, coupled to a rigid-body dynamics model, for simulating both biological (e.g., a cricket cercal hair) and artificial MEMS-based systems. The model is used to investigate hair-hair interaction between pairs of hairs and quantify the extent of so-called viscous coupling. The results show that the extent to which hairs are coupled depends on the mounting properties of the hairs and the frequency at which they are driven. In particular, it is shown that for equal length hairs, viscous coupling is suppressed when they are driven near the natural frequency of the undamped system and the damping coefficient at the base is small. Further, for certain configurations, the motion of a hair can be enhanced by the presence of nearby hairs. The usefulness of the model in designing artificial systems is discussed.
Asymptotic behavior of coupled linear systems modeling suspension bridges
NASA Astrophysics Data System (ADS)
Dell'Oro, Filippo; Giorgi, Claudio; Pata, Vittorino
2015-06-01
We consider the coupled linear system describing the vibrations of a string-beam system related to the well-known Lazer-McKenna suspension bridge model. For ɛ > 0 and k > 0, the decay properties of the solution semigroup are discussed in dependence of the nonnegative parameters γ and h, which are responsible for the damping effects.
Reheating in non-minimal derivative coupling model
Sadjadi, H. Mohseni; Goodarzi, Parviz E-mail: p_goodarzi@ut.ac.ir
2013-02-01
We consider a model with non-minimal derivative coupling of inflaton to gravity. The reheating process during rapid oscillation of the inflaton is studied and the reheating temperature is obtained. Behaviors of the inflaton and produced radiation in this era are discussed.
An efficient model for coupling structural vibrations with acoustic radiation
NASA Technical Reports Server (NTRS)
Frendi, Abdelkader; Maestrello, Lucio; Ting, LU
1993-01-01
The scattering of an incident wave by a flexible panel is studied. The panel vibration is governed by the nonlinear plate equations while the loading on the panel, which is the pressure difference across the panel, depends on the reflected and transmitted waves. Two models are used to calculate this structural-acoustic interaction problem. One solves the three dimensional nonlinear Euler equations for the flow-field coupled with the plate equations (the fully coupled model). The second uses the linear wave equation for the acoustic field and expresses the load as a double integral involving the panel oscillation (the decoupled model). The panel oscillation governed by a system of integro-differential equations is solved numerically and the acoustic field is then defined by an explicit formula. Numerical results are obtained using the two models for linear and nonlinear panel vibrations. The predictions given by these two models are in good agreement but the computational time needed for the 'fully coupled model' is 60 times longer than that for 'the decoupled model'.
Coupled Particulate and Continuum Model for Nanoparticle Targeted Delivery
Tan, Jifu; Wang, Shunqiang; Yang, Jie; Liu, Yaling
2013-01-01
Prediction of nanoparticle (NP) distribution in a vasculature involves transport phenomena at various scales and is crucial for the evaluation of NP delivery efficiency. A combined particulate and continuum model is developed to model NP transport and delivery processes. In the particulate model ligand-receptor binding kinetics is coupled with Brownian dynamics to study NP binding on a microscale. An analytical formula is derived to link molecular level binding parameters to particulate level adhesion and detachment rates. The obtained NP adhesion rates are then coupled with a convection-diffusion-reaction model to study NP transport and delivery at macroscale. The binding results of the continuum model agree well with those from the particulate model. The effects of shear rate, particle size and vascular geometry on NP adhesion are investigated. Attachment rates predicted by the analytical formula also agree reasonably well with the experimental data reported in literature. The developed coupled model that links ligand-receptor binding dynamics to NP adhesion rate along with macroscale transport and delivery processes may serve as a faster evaluation and prediction tool to determine NP distribution in complex vascular networks. PMID:23729869
An efficient model for coupling structural vibrations with acoustic radiation
NASA Astrophysics Data System (ADS)
Frendi, Abdelkader; Maestrello, Lucio; Ting, Lu
1993-04-01
The scattering of an incident wave by a flexible panel is studied. The panel vibration is governed by the nonlinear plate equations while the loading on the panel, which is the pressure difference across the panel, depends on the reflected and transmitted waves. Two models are used to calculate this structural-acoustic interaction problem. One solves the three dimensional nonlinear Euler equations for the flow-field coupled with the plate equations (the fully coupled model). The second uses the linear wave equation for the acoustic field and expresses the load as a double integral involving the panel oscillation (the decoupled model). The panel oscillation governed by a system of integro-differential equations is solved numerically and the acoustic field is then defined by an explicit formula. Numerical results are obtained using the two models for linear and nonlinear panel vibrations. The predictions given by these two models are in good agreement but the computational time needed for the 'fully coupled model' is 60 times longer than that for 'the decoupled model'.
Mutual coupling, channel model, and BER for curvilinear antenna arrays
NASA Astrophysics Data System (ADS)
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 coupling for predicting a developmental patterning process
NASA Astrophysics Data System (ADS)
Dhulekar, Nimit; Oztan, Basak; Yener, Bülent
2016-03-01
Physics-based-theoretical models have been used to predict developmental patterning processes such as branching morphogenesis for over half a century. While such techniques are quite successful in understanding the patterning processes in organs such as the lung and the kidney, they are unable to accurately model the processes in other organs such as the submandibular salivary gland. One possible reason is the detachment of these models from data that describe the underlying biological process. This hypothesis coupled with the increasing availability of high quality data has made discrete, data-driven models attractive alternatives. These models are based on extracting features from data to describe the patterns and their time evolving multivariate statistics. These discrete models have low computational complexity and comparable or better accuracy than the continuous models. This paper presents a case study for coupling continuous-physics-based and discrete-empirical-models to address the prediction of cleft formation during the early stages of branching morphogenesis in mouse submandibular salivary glands (SMG). Given a time-lapse movie of a growing SMG, first we build a descriptive model that captures the underlying biological process and quantifies this ground truth. Tissue-scale (global) morphological features are used to characterize the biological ground truth. Second, we formulate a predictive model using the level-set method that simulates branching morphogenesis. This model successfully predicts the topological evolution, however, it is blind to the cellular organization, and cell-to-cell interactions occurring inside a gland; information that is available in the image data. Our primary objective via this study is to couple the continuous level set model with a discrete graph theory model that captures the cellular organization but ignores the forces that determine the evolution of the gland surface, i.e. formation of clefts and buds. We compared the
Predictability of a coupled ocean-atmosphere model
NASA Technical Reports Server (NTRS)
Goswami, B. N.; Shukla, J.
1991-01-01
A study is presented to determine the limits on the predictability of the coupled ocean-atmosphere system. Following the classical methods developed for atmospheric predictability studies, the model used is one of the simplest that realistically reproduces many of the important features of the observed interannual variability of sea surface temperature in the tropical Pacific Ocean when forced by observed wind stresses. As no reasonable analysis is available for all the fields, initial conditions for these prediction experiments were taken from a model control run in which the ocean model was forced by the observed surface winds. The atmospheric component of the coupled model is not capable of accurately simulating the large-scale components of the observed wind stress.
NASA Astrophysics Data System (ADS)
Deppenmeier, Anna-Lena; Hazeleger, Wilco; Haarsma, Rein; Prodhomme, Chloé; Exarchou, Eleftheria; Doblas-Reyes, Francisco J.
2016-04-01
State-of-the-art coupled general circulation models (CGCMs) still fail to simulate the mean state and variability of the tropical Atlantic (TA) climate correctly. We investigate the importance of air-sea interaction at different regions in the TA by means of performing partially coupled sensitivity experiments with the state-of-the-art CGCM EC-Earth3.1. All simulations are intialised from the observed climate state. By studying the initial drift in sensitivity experiments we obtain insight into the tropical dynamics and sources of model bias. We test the influence of realistic wind stress forcing over different regions of the TA on the development of SST as well as other oceanic biases. A series of hindcasts fully initialised in May and run until the end of August are performed with prescribed ERA-Interim zonal and meridional wind stresses over three different regions: firstly, we force the entire TA from 15N - 30S. Secondly, we force the equatorial band only between 5N - 5S, and finally we force the coastal area of the Angola Benguela upwelling region between 0W and the coast and between 5S - 30N. Our setup only affects the oceanic forcing and leaves the atmosphere free to adapt, such that we can identify the air-sea interaction processes in the different regions and their effect on the SST bias in the fully coupled system. The differences between forcing the entire TA and the equatorial region only are very small, which hints to the great importance of the relatively narrow equatorial region. The coastal upwelling area does not strongly affect the equatorial region in our model. We identify the equatorial band as most susceptible to errors in the wind stress forcing and, due to the strong atmosphere-ocean coupling, as source of the main biases in our model. The partially coupled experiments with initialised seasonal hindcasts appear to be a powerful tool to identify the sources of model biases and to identify relevant air-sea interaction processes in the TA.
NASA Astrophysics Data System (ADS)
García-Senz, D.; Cabezón, R. M.; Domínguez, I.; Thielemann, F. K.
2016-03-01
Currently the number of models aimed at explaining the phenomena of type Ia supernovae is high and distinguishing between them is a must. In this work we explore the influence of rotation on the evolution of the nuclear flame that drives the explosion in the so-called gravitational confined detonation models. Assuming that the flame starts in a pointlike region slightly above the center of the white dwarf (WD) and adding a moderate amount of angular velocity to the star we follow the evolution of the deflagration using a smoothed particle hydrodynamics code. We find that the results are very dependent on the angle between the rotational axis and the line connecting the initial bubble of burned material with the center of the WD at the moment of ignition. The impact of rotation is larger for angles close to 90° because the Coriolis force on a floating element of fluid is maximum and its principal effect is to break the symmetry of the deflagration. Such symmetry breaking weakens the convergence of the nuclear flame at the antipodes of the initial ignition volume, changing the environmental conditions around the convergence region with respect to non-rotating models. These changes seem to disfavor the emergence of a detonation in the compressed volume at the antipodes and may compromise the viability of the so-called gravitational confined detonation mechanism.
García-Senz, D.; Cabezón, R. M.; Thielemann, F. K.; Domínguez, I. E-mail: ruben.cabezon@unibas.ch
2016-03-10
Currently the number of models aimed at explaining the phenomena of type Ia supernovae is high and distinguishing between them is a must. In this work we explore the influence of rotation on the evolution of the nuclear flame that drives the explosion in the so-called gravitational confined detonation models. Assuming that the flame starts in a pointlike region slightly above the center of the white dwarf (WD) and adding a moderate amount of angular velocity to the star we follow the evolution of the deflagration using a smoothed particle hydrodynamics code. We find that the results are very dependent on the angle between the rotational axis and the line connecting the initial bubble of burned material with the center of the WD at the moment of ignition. The impact of rotation is larger for angles close to 90° because the Coriolis force on a floating element of fluid is maximum and its principal effect is to break the symmetry of the deflagration. Such symmetry breaking weakens the convergence of the nuclear flame at the antipodes of the initial ignition volume, changing the environmental conditions around the convergence region with respect to non-rotating models. These changes seem to disfavor the emergence of a detonation in the compressed volume at the antipodes and may compromise the viability of the so-called gravitational confined detonation mechanism.
Frisch, E.; Johnson, C.G.
1962-05-15
A detachable coupling arrangement is described which provides for varying the length of the handle of a tool used in relatively narrow channels. The arrangement consists of mating the key and keyhole formations in the cooperating handle sections. (AEC)
Coupled Climate Model Appraisal a Benchmark for Future Studies
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 discussed here.
Drift-Scale Coupled Processes (DST and THC Seepage) Models
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 DST THC Model is used solely for the validation of the THC
A preferential vibration dissociation coupling model for nonequilibrium flowfields
NASA Technical Reports Server (NTRS)
Mcgough, David E.; Carlson, Leland A.; Gally, Thomas A.
1993-01-01
A preferential vibration-dissociation coupling model is incorporated into a radiatively coupled viscous shock laver code that also includes chemical, radiative, and thermal nonequilibrium. Stagnation point flow profiles are obtained for various Fire 2 flight conditions and for a typical 14 km/sec AOTV case, and comparisons are made with Fire 2 experimental data. Adjustments in molecular absorption coefficients are also made for several diatomic species. Based on comparisons with experimental data, very little preferential dissociation behavior is present in the Fire 2 flight conditions.
Progress in coupling models of human and coastal landscape change
NASA Astrophysics Data System (ADS)
Brad Murray, A.; Gopalakrishnan, Sathya; McNamara, Dylan E.; Smith, Martin D.
2013-04-01
Humans are increasingly altering the Earth's surface, and affecting processes that shape and reshape landscapes. In many cases, humans are reacting to landscape-change processes that represent natural hazards. Thus, the landscape is reacting to humans who are reacting to the landscape. When the timescales for landscape change are comparable to those of human dynamics, human and 'natural' components of developed environments are dynamically coupled—necessitating coupling models of human and physical/biological processes to study either environmental change or human responses. Here we focus on a case study coupling models of coastal economics and physical coastline change. In this modeling, coastline change results from patterns of wave-driven sediment transport and sea-level rise, and shoreline stabilization decisions are based on the benefits of wide beaches (capitalized into property values) balanced against the costs of stabilization. This interdisciplinary modeling highlights points that may apply to other coupled human/natural systems. First, climate change, by accelerating the rates of landscape change, tends to strengthen the coupling with human dynamics. In our case study, both increasing sea-level-rise rates and changing storm patterns tend to increase shoreline change rates, which can induce more vigorous shoreline stabilization efforts. However, property values can fall dramatically as erosion rates and stabilization costs rise, which can also lead to the abandonment of expensive stabilization methods as shoreline change rates increase. Second, socio-economic change can also strengthen the human/landscape coupling. Changing costs of shoreline stabilization can alter stabilization decisions, which in turn alters patterns of coastline change. The coupled modeling illuminates the long-range effects of localized shoreline stabilization efforts; communities arrayed along a coastline are unwittingly affecting each other's erosion rates, and therefore each
Modeling Endovascular MRI Coil Coupling with Transmit RF Excitation
Venkateswaran, Madhav; Unal, Orhan; Hurley, Samuel; Samsonov, Alexey; Wang, Peng; Fain, Sean; Kurpad, Krishna
2016-01-01
Objective To model inductive coupling of endovascular coils with transmit RF excitation for selecting coils for MRI-guided interventions. Methods Independent and computationally efficient FEM models are developed for the endovascular coil, cable, transmit excitation and imaging domain. Electromagnetic and circuit solvers are coupled to simulate net B1+ fields and induced currents and voltages. Our models are validated using the Bloch Siegert B1+ mapping sequence for a series-tuned multimode coil, capable of tracking, wireless visualization and high resolution endovascular imaging. Results Validation shows good agreement at 24, 28 and 34 μT background RF excitation within experimental limitations. Quantitative coil performance metrics agree with simulation. A parametric study demonstrates trade off in coil performance metrics when varying number of coil turns. Tracking, imaging and wireless marker multimode coil features and their integration is demonstrated in a pig study. Conclusion Developed models for the multimode coil were successfully validated. Modeling for geometric optimization and coil selection serves as a precursor to time-consuming and expensive experiments. Specific applications demonstrated include parametric optimization, coil selection for a cardiac intervention and an animal imaging experiment. Significance Our modular, adaptable and computationally efficient modeling approach enables rapid comparison, selection and optimization of inductively-coupled coils for MRI-guided interventions. PMID:26960218
Coupled fermion-kink system in Jackiw-Rebbi model
NASA Astrophysics Data System (ADS)
Amado, A.; Mohammadi, A.
2017-07-01
In this paper, we study Jackiw-Rebbi model, in which a massless fermion is coupled to the kink of λ φ ^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.
Electromagnetic modeling of edge coupled quantum well infrared photodetectors
NASA Astrophysics Data System (ADS)
Choi, K. K.
2012-06-01
Edge coupling through a 45° facet is the standard approach in characterizing quantum well infrared photodetector materials. From the spectral responsivity, the material absorption coefficient can be deduced from a classical model. However, this classical model has not been closely examined by a rigorous theory. In this work, we apply finite element electromagnetic modeling to obtain the detector quantum efficiency under this geometry and compare the result with the classical prediction. Remarkably, we find that both models give the same result at this particular angle while they differ significantly at other angles.
Mathematical model of mouse embryonic cardiomyocyte excitation-contraction coupling.
Korhonen, Topi; Rapila, Risto; Tavi, Pasi
2008-10-01
Excitation-contraction (E-C) coupling is the mechanism that connects the electrical excitation with cardiomyocyte contraction. Embryonic cardiomyocytes are not only capable of generating action potential (AP)-induced Ca(2+) signals and contractions (E-C coupling), but they also can induce spontaneous pacemaking activity. The spontaneous activity originates from spontaneous Ca(2+) releases from the sarcoplasmic reticulum (SR), which trigger APs via the Na(+)/Ca(2+) exchanger (NCX). In the AP-driven mode, an external stimulus triggers an AP and activates voltage-activated Ca(2+) intrusion to the cell. These complex and unique features of the embryonic cardiomyocyte pacemaking and E-C coupling have never been assessed with mathematical modeling. Here, we suggest a novel mathematical model explaining how both of these mechanisms can coexist in the same embryonic cardiomyocytes. In addition to experimentally characterized ion currents, the model includes novel heterogeneous cytosolic Ca(2+) dynamics and oscillatory SR Ca(2+) handling. The model reproduces faithfully the experimentally observed fundamental features of both E-C coupling and pacemaking. We further validate our model by simulating the effect of genetic modifications on the hyperpolarization-activated current, NCX, and the SR Ca(2+) buffer protein calreticulin. In these simulations, the model produces a similar functional alteration to that observed previously in the genetically engineered mice, and thus provides mechanistic explanations for the cardiac phenotypes of these animals. In general, this study presents the first model explaining the underlying cellular mechanism for the origin and the regulation of the heartbeat in early embryonic cardiomyocytes.
Mathematical Model of Mouse Embryonic Cardiomyocyte Excitation–Contraction Coupling
Korhonen, Topi; Rapila, Risto; Tavi, Pasi
2008-01-01
Excitation–contraction (E–C) coupling is the mechanism that connects the electrical excitation with cardiomyocyte contraction. Embryonic cardiomyocytes are not only capable of generating action potential (AP)-induced Ca2+ signals and contractions (E–C coupling), but they also can induce spontaneous pacemaking activity. The spontaneous activity originates from spontaneous Ca2+ releases from the sarcoplasmic reticulum (SR), which trigger APs via the Na+/Ca2+ exchanger (NCX). In the AP-driven mode, an external stimulus triggers an AP and activates voltage-activated Ca2+ intrusion to the cell. These complex and unique features of the embryonic cardiomyocyte pacemaking and E–C coupling have never been assessed with mathematical modeling. Here, we suggest a novel mathematical model explaining how both of these mechanisms can coexist in the same embryonic cardiomyocytes. In addition to experimentally characterized ion currents, the model includes novel heterogeneous cytosolic Ca2+ dynamics and oscillatory SR Ca2+ handling. The model reproduces faithfully the experimentally observed fundamental features of both E–C coupling and pacemaking. We further validate our model by simulating the effect of genetic modifications on the hyperpolarization-activated current, NCX, and the SR Ca2+ buffer protein calreticulin. In these simulations, the model produces a similar functional alteration to that observed previously in the genetically engineered mice, and thus provides mechanistic explanations for the cardiac phenotypes of these animals. In general, this study presents the first model explaining the underlying cellular mechanism for the origin and the regulation of the heartbeat in early embryonic cardiomyocytes. PMID:18794378
Cascading load model in interdependent networks with coupled strength
NASA Astrophysics Data System (ADS)
Wang, Jianwei; Li, Yun; Zheng, Qiaofang
2015-07-01
Considering the coupled strength between interdependent networks, we introduce a new method to define the initial load on an edge and propose a cascading load model in interdependent networks. We explore the robustness of the interdependent networks against cascading failures by two measures, i.e., the critical threshold βc quantifying the whole robustness of the interdependent networks to avoid the emergence of cascading failure, and the new proposed smallest capacity threshold βc,s quantifying the degree of the worst damage of the interdependent networks. We numerically find that the AL (high-degree nodes in network A connect high-degree ones in network B) link between two networks can greatly enhance the robust level of the interdependent networks against cascading failures. Especially we observe that the values of βc in the interdependent networks with both the DL (high-degree nodes in network A connect low-degree ones in network B) link and the RL (nodes in network A randomly connect ones in network B) link increase monotonically with the coupled strength, while the values of βc,s in the interdependent networks with three types of link patterns almost monotonically decreases with the coupled strength. In the interdependent networks with the AL, the value of βc first decreases and then increases with the coupled strength. We further explain this interesting phenomenon by a simple graph. In addition, we study the influence of the coupled strength on the efficiency of two attacks to destroy the interdependent networks. We find that, when the coupled strength between two networks is weaker, attacking the edges with the lower load is more easier to trigger the cascading propagation than attacking the nodes with the higher load, however, when the coupled strength in two networks is stronger, the case is on the contrary. Finally, we give reasonable explanations from the local perspective of the total capacity of all neighboring edges of a failed edge.
Progress and challenges in coupled hydrodynamic-ecological estuarine modeling
Ganju, Neil K.; Brush, Mark J.; Rashleigh, Brenda; Aretxabaleta, Alfredo L.; del Barrio, Pilar; Grear, Jason S.; Harris, Lora A.; Lake, Samuel J.; McCardell, Grant; O’Donnell, James; Ralston, David K.; Signell, Richard P.; Testa, Jeremy M.; Vaudrey, Jamie M.P.
2016-01-01
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 power, and incorporation of uncertainty. Coupled hydrodynamic-ecological models have been used to assess ecosystem processes and interactions, simulate future scenarios, and evaluate remedial actions in response to eutrophication, habitat loss, and freshwater diversion. The need to couple hydrodynamic and ecological models to address research and management questions is clear, because dynamic feedbacks between biotic and physical processes are critical interactions within ecosystems. In this review we present historical and modern perspectives on estuarine hydrodynamic and ecological modeling, consider model limitations, and address aspects of model linkage, skill assessment, and complexity. We discuss the balance between spatial and temporal resolution and present examples using different spatiotemporal scales. Finally, we recommend future lines of inquiry, approaches to balance complexity and uncertainty, and model transparency and utility. It is idealistic to think we can pursue a “theory of everything” for estuarine models, but recent advances suggest that models for both scientific investigations and management applications will continue to improve in terms of realism, precision, and accuracy. PMID:27721675
A bidirectional coupling procedure applied to multiscale respiratory modeling
NASA Astrophysics Data System (ADS)
Kuprat, A. P.; Kabilan, S.; Carson, J. P.; Corley, R. A.; Einstein, D. R.
2013-07-01
In this study, we present a novel multiscale computational framework for efficiently linking multiple lower-dimensional models describing the distal lung mechanics to imaging-based 3D computational fluid dynamics (CFDs) models of the upper pulmonary airways in order to incorporate physiologically appropriate outlet boundary conditions. The framework is an extension of the modified Newton's method with nonlinear Krylov accelerator developed by Carlson and Miller [1], Miller [2] and Scott and Fenves [3]. Our extensions include the retention of subspace information over multiple timesteps, and a special correction at the end of a timestep that allows for corrections to be accepted with verified low residual with as little as a single residual evaluation per timestep on average. In the case of a single residual evaluation per timestep, the method has zero additional computational cost compared to uncoupled or unidirectionally coupled simulations. We expect these enhancements to be generally applicable to other multiscale coupling applications where timestepping occurs. In addition we have developed a "pressure-drop" residual which allows for stable coupling of flows between a 3D incompressible CFD application and another (lower-dimensional) fluid system. We expect this residual to also be useful for coupling non-respiratory incompressible fluid applications, such as multiscale simulations involving blood flow. The lower-dimensional models that are considered in this study are sets of simple ordinary differential equations (ODEs) representing the compliant mechanics of symmetric human pulmonary airway trees. To validate the method, we compare the predictions of hybrid CFD-ODE models against an ODE-only model of pulmonary airflow in an idealized geometry. Subsequently, we couple multiple sets of ODEs describing the distal lung to an imaging-based human lung geometry. Boundary conditions in these models consist of atmospheric pressure at the mouth and intrapleural
A Bidirectional Coupling Procedure Applied to Multiscale Respiratory Modeling.
Kuprat, A P; Kabilan, S; Carson, J P; Corley, R A; Einstein, D R
2013-07-01
In this study, we present a novel multiscale computational framework for efficiently linking multiple lower-dimensional models describing the distal lung mechanics to imaging-based 3D computational fluid dynamics (CFD) models of the upper pulmonary airways in order to incorporate physiologically appropriate outlet boundary conditions. The framework is an extension of the Modified Newton's Method with nonlinear Krylov accelerator developed by Carlson and Miller [1, 2, 3]. Our extensions include the retention of subspace information over multiple timesteps, and a special correction at the end of a timestep that allows for corrections to be accepted with verified low residual with as little as a single residual evaluation per timestep on average. In the case of a single residual evaluation per timestep, the method has zero additional computational cost compared to uncoupled or unidirectionally coupled simulations. We expect these enhancements to be generally applicable to other multiscale coupling applications where timestepping occurs. In addition we have developed a "pressure-drop" residual which allows for stable coupling of flows between a 3D incompressible CFD application and another (lower-dimensional) fluid system. We expect this residual to also be useful for coupling non-respiratory incompressible fluid applications, such as multiscale simulations involving blood flow. The lower-dimensional models that are considered in this study are sets of simple ordinary differential equations (ODEs) representing the compliant mechanics of symmetric human pulmonary airway trees. To validate the method, we compare the predictions of hybrid CFD-ODE models against an ODE-only model of pulmonary airflow in an idealized geometry. Subsequently, we couple multiple sets of ODEs describing the distal lung to an imaging-based human lung geometry. Boundary conditions in these models consist of atmospheric pressure at the mouth and intrapleural pressure applied to the multiple sets
A Bidirectional Coupling Procedure Applied to Multiscale Respiratory Modeling
Kuprat, Andrew P.; Kabilan, Senthil; Carson, James P.; Corley, Richard A.; Einstein, Daniel R.
2013-07-01
In this study, we present a novel multiscale computational framework for efficiently linking multiple lower-dimensional models describing the distal lung mechanics to imaging-based 3D computational fluid dynamics (CFD) models of the upper pulmonary airways in order to incorporate physiologically appropriate outlet boundary conditions. The framework is an extension of the Modified Newton’s Method with nonlinear Krylov accelerator developed by Carlson and Miller [1, 2, 3]. Our extensions include the retention of subspace information over multiple timesteps, and a special correction at the end of a timestep that allows for corrections to be accepted with verified low residual with as little as a single residual evaluation per timestep on average. In the case of a single residual evaluation per timestep, the method has zero additional computational cost compared to uncoupled or unidirectionally coupled simulations. We expect these enhancements to be generally applicable to other multiscale coupling applications where timestepping occurs. In addition we have developed a “pressure-drop” residual which allows for stable coupling of flows between a 3D incompressible CFD application and another (lower-dimensional) fluid system. We expect this residual to also be useful for coupling non-respiratory incompressible fluid applications, such as multiscale simulations involving blood flow. The lower-dimensional models that are considered in this study are sets of simple ordinary differential equations (ODEs) representing the compliant mechanics of symmetric human pulmonary airway trees. To validate the method, we compare the predictions of hybrid CFD-ODE models against an ODE-only model of pulmonary airflow in an idealized geometry. Subsequently, we couple multiple sets of ODEs describing the distal lung to an imaging-based human lung geometry. Boundary conditions in these models consist of atmospheric pressure at the mouth and intrapleural pressure applied to the multiple
A bidirectional coupling procedure applied to multiscale respiratory modeling
Kuprat, A.P.; Kabilan, S.; Carson, J.P.; Corley, R.A.; Einstein, D.R.
2013-07-01
In this study, we present a novel multiscale computational framework for efficiently linking multiple lower-dimensional models describing the distal lung mechanics to imaging-based 3D computational fluid dynamics (CFDs) models of the upper pulmonary airways in order to incorporate physiologically appropriate outlet boundary conditions. The framework is an extension of the modified Newton’s method with nonlinear Krylov accelerator developed by Carlson and Miller [1], Miller [2] and Scott and Fenves [3]. Our extensions include the retention of subspace information over multiple timesteps, and a special correction at the end of a timestep that allows for corrections to be accepted with verified low residual with as little as a single residual evaluation per timestep on average. In the case of a single residual evaluation per timestep, the method has zero additional computational cost compared to uncoupled or unidirectionally coupled simulations. We expect these enhancements to be generally applicable to other multiscale coupling applications where timestepping occurs. In addition we have developed a “pressure-drop” residual which allows for stable coupling of flows between a 3D incompressible CFD application and another (lower-dimensional) fluid system. We expect this residual to also be useful for coupling non-respiratory incompressible fluid applications, such as multiscale simulations involving blood flow. The lower-dimensional models that are considered in this study are sets of simple ordinary differential equations (ODEs) representing the compliant mechanics of symmetric human pulmonary airway trees. To validate the method, we compare the predictions of hybrid CFD–ODE models against an ODE-only model of pulmonary airflow in an idealized geometry. Subsequently, we couple multiple sets of ODEs describing the distal lung to an imaging-based human lung geometry. Boundary conditions in these models consist of atmospheric pressure at the mouth and intrapleural
Acoustic Modeling Using a Three-Dimensional Coupled-Mode Model
2013-09-30
a comparison of the 3D coupled-mode solution to a finite element method ( FEM ) solution, (2) ranging estimates from horizontal multipath in a...mode code for environments with elastic layers. RESULTS Comparison of the 3D coupled-mode solution to a FEM solution As described above, in...assumption are examined by comparing the solution from the 3D coupled-mode model to a solution obtained using a FEM model applied with the
Modeling, Calibration, and Sensitivity Analysis of Coupled Land-Surface Models
NASA Astrophysics Data System (ADS)
Liu, Y.; Gupta, H. V.; Bastidas, L. A.; Sorooshian, S.
2002-12-01
To better understand various land-surface hydrological processes, it is desirable and pressing to extend land-surface modeling from off-line modes to coupled modes to explore the significance of various land surface-atmospheric interactions in regulating the energy and water balance of the hydrologic cycle. While it is extremely difficult to directly test the parameterizations of a global climate model due to the complexity, a locally coupled single-column model provides a favorable environment for investigations into the complicated interactions between the land surface and the overlying atmosphere. In this research, the off-line NCAR LSM and the coupled NCAR Single-column Community Climate Model (NCAR SCCM) are used. Extensive efforts have been focused on the impacts that the coupling of the two systems may have on the sensitivities of the land-surface model to both land-surface parameters and land-surface parameterizations. Additional efforts are directed to the comparisons of results from off-line and coupled calibration experiments using the optimization algorithm MOCOM-UA and IOP data sets from the Atmosphere Radiation Measurement-Cloud and Radiation Testbed (ARM-CART) project. Possibilities of calibrating some atmospheric parameters in the coupled model are also explored. Preliminary results show that the parameterization of surface energy and water balance is crucial in coupled systems and that the land-atmosphere coupling can significantly affect the estimations of land-surface parameters. In addition, it has been found that solar radiation and precipitation play an extremely important role in a coupled land-surface model by dominating the two-way interactions within the coupled system. This study will also enable us to investigate into the feasibility of applying the parameter estimation methods used for point-validations of LSM over grid-boxes in a coupled environment, and facilitate following studies on the effects that a coupled environment would have
Coupled continuum and molecular model of flow through fibrous filter
NASA Astrophysics Data System (ADS)
Zhao, Shunliu; Povitsky, Alex
2013-11-01
A coupled approach combining the continuum boundary singularity method (BSM) and the molecular direct simulation Monte Carlo (DSMC) is developed and validated using Taylor-Couette flow and the flow about a single fiber confined between two parallel walls. In the proposed approach, the DSMC is applied to an annular region enclosing the fiber and the BSM is employed in the entire flow domain. The parameters used in the DSMC and the coupling procedure, such as the number of simulated particles, the cell size, and the size of the coupling zone are determined by inspecting the accuracy of pressure drop obtained for the range of Knudsen numbers between zero and unity. The developed approach is used to study flowfield of fibrous filtration flows. It is observed that in the partial-slip flow regime, Kn ⩽ 0.25, the results obtained by the proposed coupled BSM-DSMC method match the solution by BSM combined with the heuristic partial-slip boundary conditions. For transition molecular-to-continuum Knudsen numbers, 0.25 < Kn ⩽ 1, the difference in pressure drop and velocity between these two approaches is significant. This difference increases with the Knudsen number that confirms the usefulness of coupled continuum and molecular methods in numerical modeling of transition low Reynolds number flows in fibrous filters.
The dispersion of magnetic-Coriolis waves in planetary cores
NASA Astrophysics Data System (ADS)
Bardsley, O. P.; Davidson, P. A.
2017-07-01
We consider the dispersion of waves in a rapidly rotating, Boussinesq fluid which is threaded by a magnetic field and stirred by slowly gravitating buoyant blobs. Motivated by dynamics in the core of the Earth, we focus on the evolution of inertial-Alfvén wave packets radiated from the buoyant anomalies. These waves resemble conventional low-frequency inertial waves, in the sense that energy disperses on the fast timescale of the background rotation rate, though they also exhibit slower Alfvén-like propagation along magnetic field lines. When the magnetic field is uniform, inertial-Alfvén waves automatically focus energy radiation onto the rotation axis, a property they share with conventional low-frequency inertial waves in the hydrodynamic case, and which ensures that they dominate the dispersion pattern. However, the situation changes significantly when the magnetic field, B, is non-uniform. In particular, we show any non-uniformity of B causes inertial-Alfvén waves to evolve into a more general form of magnetic-Coriolis (MC) wave, and that these waves refract, dispersing somewhat off-axis. Moreover, if inertial-Alfvén waves are launched near the equator they can be confined to low latitudes by a critical layer at which the axial group velocity drops to zero. Given that the magnetic field in a planetary core is inevitably non-uniform, we conclude that quasi-geostrophy is most likely achieved through a combination of weakly modified inertial waves and a form of slightly off-axis MC wave in which the inertial and Alfvén frequencies are comparable.
A Coupled General Circulation Model of the Archean Earth
NASA Astrophysics Data System (ADS)
Wolf, E. T.; Toon, O. B.
2011-12-01
We present results from a new coupled general circulation model suitable for deep paleoclimate studies. Particular interest is given to the faint young Sun paradox. The model is based on the Community Earth System Model maintained by the National Center for Atmospheric Research [1]. Prognostic atmosphere, ocean, land, ice, and hydrological cycle models are coupled. A new correlated-k radiative transfer model has been implemented allowing accurate flux calculations for anoxic atmospheres containing high concentrations of CO2 and CH4 [2, 3]. This model represents a significant improvement upon one-dimensional radiative-convective climate models used previously to study ancient climate [4]. Cloud and ice albedo feedbacks will be accurately quantified and new constraints on Archean surface temperatures will be revealed. References [1] Collins W.D. et al. "Description of the NCAR Community Atmosphere Model (CAM 3.0)." NCAR Technical Note, 2004. [2] Toon O.B., McKay, C.P., Ackerman, T.P. "Rapid Calculation of Radiative Heating Rates and Photodissociation Rates in Inhomogeneous Multiple Scattering Atmospheres." J. Geo. Res., 94(D13), 16287 - 16301, 1989. [3] Mlawer, E.J., et al. "Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave." J. Geo. Res., 102(D14), 16663 - 16682, 1997. [4] Kasting J.F., Pollack, J.B., Crisp, D. "Effects of High CO2 Levels on Surface Temperature and Atmospheric Oxidation State of the Early Earth." J. Atm. Chem., 1, 403-428, 1984.
NASA Astrophysics Data System (ADS)
Stryker, J.; Wemple, B.; Bomblies, A.
2017-03-01
In addition to surface erosion, stream bank erosion and failure contributes significant sediment and sediment-bound nutrients to receiving waters during high flow events. However, distributed and mechanistic simulation of stream bank sediment contribution to sediment loads in a watershed has not been achieved. Here we present a full coupling of existing distributed watershed and bank stability models and apply the resulting model to the Mad River in central Vermont. We fully coupled the Bank Stability and Toe Erosion Model (BSTEM) with the Distributed Hydrology Soil Vegetation Model (DHSVM) to allow the simulation of stream bank erosion and potential failure in a spatially explicit environment. We demonstrate the model's ability to simulate the impacts of unstable streams on sediment mobilization and transport within a watershed and discuss the model's capability to simulate watershed sediment loading under climate change. The calibrated model simulates total suspended sediment loads and reproduces variability in suspended sediment concentrations at watershed and subbasin outlets. In addition, characteristics such as land use and road-to-stream ratio of subbasins are shown to impact the relative proportions of sediment mobilized by overland erosion, erosion of roads, and stream bank erosion and failure in the subbasins and watershed. This coupled model will advance mechanistic simulation of suspended sediment mobilization and transport from watersheds, which will be particularly valuable for investigating the potential impacts of climate and land use changes, as well as extreme events.
Pathological gambling and couple: towards an integrative systemic model.
Cunha, Diana; Relvas, Ana Paula
2014-06-01
This article is a critical literature review of pathological gambling focused in the family factors, particularly in the couple dynamics. Its main goal is to develop an explicative integrative systemic model of pathological gambling, based in these couple dynamics. To achieve that aim, a bibliography search was made, using on-line data bases (e.g., EBSCO Host) and recognized books in pathological gambling subject, as well as in the systemic approach in general. This process privileged the recent works (about 70 % of the reviewed literature was published in the last decade), however, also considered some classic works (the oldest one dates back to 1970). The guiding focus of this literature search evolves according to the following steps: (1) search of general comprehension of pathological gambling (19 references), (2) search specification to the subject "pathological gambling and family" (24 references), (3) search specification to the subject "pathological gambling and couple"(11 references), (4) search of systemic information which integrates the evidence resulted in the previous steps (4 references). The developed model is constituted by different levels of systemic complexity (social context, family of origin, couple and individual) and explains the problem as a signal of perturbation in the marital subsystem vital functions (e.g., power and control) though the regularities of marital dynamics of pathological gamblers. Furthermore, it gives theoretical evidence of the systemic familiar intervention in the pathological gambling.
Coriolis effects on rotating Hele-Shaw flows: a conformal-mapping approach.
Miranda, José A; Gadêlha, Hermes; Dorsey, Alan T
2010-12-01
The zero surface tension fluid-fluid interface dynamics in a radial Hele-Shaw cell driven by both injection and rotation is studied by a conformal-mapping approach. The situation in which one of the fluids is inviscid and has negligible density is analyzed. When Coriolis force effects are ignored, exact solutions of the zero surface tension rotating Hele-Shaw problem with injection reveal suppression of cusp singularities for sufficiently high rotation rates. We study how the Coriolis force affects the time-dependent solutions of the problem, and the development of finite time singularities. By employing Richardson's harmonic moments approach we obtain conformal maps which describe the time evolution of the fluid boundary. Our results demonstrate that the inertial Coriolis contribution plays an important role in determining the time for cusp formation. Moreover, it introduces a phase drift that makes the evolving patterns rotate. The Coriolis force acts against centrifugal effects, promoting (inhibiting) cusp breakdown if the more viscous and dense fluid lies outside (inside) the interface. Despite the presence of Coriolis effects, the occurrence of finger bending events has not been detected in the exact solutions.
A Coupled Simulation Architecture for Agent-Based/Geohydrological Modelling
NASA Astrophysics Data System (ADS)
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).
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; 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.
Development of a coupled wave-flow-vegetation interaction model
NASA Astrophysics Data System (ADS)
Beudin, Alexis; Kalra, Tarandeep S.; Ganju, Neil K.; Warner, John C.
2017-03-01
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.
Coupled vibro-acoustic model updating using frequency response functions
NASA Astrophysics Data System (ADS)
Nehete, D. V.; Modak, S. V.; Gupta, K.
2016-03-01
Interior noise in cavities of motorized vehicles is of increasing significance due to the lightweight design of these structures. Accurate coupled vibro-acoustic FE models of such cavities are required so as to allow a reliable design and analysis. It is, however, experienced that the vibro-acoustic predictions using these models do not often correlate acceptably well with the experimental measurements and hence require model updating. Both the structural and the acoustic parameters addressing the stiffness as well as the damping modeling inaccuracies need to be considered simultaneously in the model updating framework in order to obtain an accurate estimate of these parameters. It is also noted that the acoustic absorption properties are generally frequency dependent. This makes use of modal data based methods for updating vibro-acoustic FE models difficult. In view of this, the present paper proposes a method based on vibro-acoustic frequency response functions that allow updating of a coupled FE model by considering simultaneously the parameters associated with both the structural as well as the acoustic model of the cavity. The effectiveness of the proposed method is demonstrated through numerical studies on a 3D rectangular box cavity with a flexible plate. Updating parameters related to the material property, stiffness of joints between the plate and the rectangular cavity and the properties of absorbing surfaces of the acoustic cavity are considered. The robustness of the method under presence of noise is also studied.
MOUNTAIN-SCALE COUPLED PROCESSES (TH/THC/THM)MODELS
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 water and gas
Coupled Inverted Pendula Model of Competition and Cooperation
NASA Astrophysics Data System (ADS)
Yoshida, Katsutoshi; Ohta, Hiroki
A coupled inverted pendula model of competition and cooperation is proposed to develop a purely mechanical implementation comparable to the Lotka-Volterra competition model. It is shown numerically that the proposed model can produce the four stable equilibriums analogous to ecological coexistence, two states of dominance, and scramble. The authors also propose two types of open-loop strategies to switch the equilibriums. The proposed strategies can be associated with an attack and a counter attack of agents through a metaphor of martial arts.
Nonrelativistic approaches derived from point-coupling relativistic models
Lourenco, O.; Dutra, M.; Delfino, A.; Sa Martins, J. S.
2010-03-15
We construct nonrelativistic versions of relativistic nonlinear hadronic point-coupling models, based on new normalized spinor wave functions after small component reduction. These expansions give us energy density functionals that can be compared to their relativistic counterparts. We show that the agreement between the nonrelativistic limit approach and the Skyrme parametrizations becomes strongly dependent on the incompressibility of each model. We also show that the particular case A=B=0 (Walecka model) leads to the same energy density functional of the Skyrme parametrizations SV and ZR2, while the truncation scheme, up to order {rho}{sup 3}, leads to parametrizations for which {sigma}=1.
Coupling lattice Boltzmann and molecular dynamics models for dense fluids
NASA Astrophysics Data System (ADS)
Dupuis, A.; Kotsalis, E. M.; Koumoutsakos, P.
2007-04-01
We propose a hybrid model, coupling lattice Boltzmann (LB) and molecular dynamics (MD) models, for the simulation of dense fluids. Time and length scales are decoupled by using an iterative Schwarz domain decomposition algorithm. The MD and LB formulations communicate via the exchange of velocities and velocity gradients at the interface. We validate the present LB-MD model in simulations of two- and three-dimensional flows of liquid argon past and through a carbon nanotube. Comparisons with existing hybrid algorithms and with reference MD solutions demonstrate the validity of the present approach.
Coupling lattice Boltzmann and molecular dynamics models for dense fluids.
Dupuis, A; Kotsalis, E M; Koumoutsakos, P
2007-04-01
We propose a hybrid model, coupling lattice Boltzmann (LB) and molecular dynamics (MD) models, for the simulation of dense fluids. Time and length scales are decoupled by using an iterative Schwarz domain decomposition algorithm. The MD and LB formulations communicate via the exchange of velocities and velocity gradients at the interface. We validate the present LB-MD model in simulations of two- and three-dimensional flows of liquid argon past and through a carbon nanotube. Comparisons with existing hybrid algorithms and with reference MD solutions demonstrate the validity of the present approach.
A coupled model for intragranular deformation and chemical diffusion
NASA Astrophysics Data System (ADS)
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 land-atmosphere modeling of methane emissions with WRF
NASA Astrophysics Data System (ADS)
Taylor, D.
2013-12-01
This project aims to couple a soil model for methane transport to an atmospheric model to predict methane emissions and dispersion. Methane is a potent greenhouse gas, 20 times as efficient at trapping heat in the atmosphere as the most prevalent greenhouse gas, carbon dioxide. It has been estimated that 60% of methane emissions in the earth's atmosphere come from anthropogenic sources, 17% of which comes from landfills, making landfills the third largest contributor of human-generated methane. Due to high costs and non-ideal weather conditions, field measurements of methane concentration at landfills are difficult and infrequent, so estimates of annual emissions from landfills are not very accurate. We plan to create a coupled land-atmosphere model that takes production and oxidation of methane into account when calculating methane emissions. This model will give a better understanding of how much methane is emitted annually from a given landfill and assist with monitoring efforts. It will also demonstrate the magnitude of diurnal and seasonal variations in methane emissions, which may identify errors in yearly methane emissions estimates made by extrapolating from a small number of field measurements. As a first step, an existing land-surface model, Noah, is modified to compute the transport of oxygen and methane along a 1-D soil column. Surface emissions are calculated using a gradient flux method with a boundary layer conductance that depends on the wind speed. These modifications to the land-surface model will be added to the Weather Research and Forecasting model to predict atmospheric dispersion of methane emitted by landfills. Comparisons to observations are made at two different landfill sites to validate the coupled model.
Conformal Loop quantization of gravity coupled to the standard model
NASA Astrophysics Data System (ADS)
Pullin, Jorge; Gambini, Rodolfo
2016-03-01
We consider a local conformal invariant coupling of the standard model to gravity free of any dimensional parameter. The theory is formulated in order to have a quantized version that admits a spin network description at the kinematical level like that of loop quantum gravity. The Gauss constraint, the diffeomorphism constraint and the conformal constraint are automatically satisfied and the standard inner product of the spin-network basis still holds. The resulting theory has resemblances with the Bars-Steinhardt-Turok local conformal theory, except it admits a canonical quantization in terms of loops. By considering a gauge fixed version of the theory we show that the Standard model coupled to gravity is recovered and the Higgs boson acquires mass. This in turn induces via the standard mechanism masses for massive bosons, baryons and leptons.
Transient and steady state modelling of a coupled WECS
NASA Astrophysics Data System (ADS)
Nathan, G. K.; Tan, J. K.
The paper presents a method for simulation of a wind turbine using a dc motor. The armature and field voltages of the dc motor are independently regulated to obtain torque-speed characteristics which correspond to those of a wind turbine at different wind speeds. The mass moment of inertia of the wind turbine is represented by adding a rotating mass to a parallel shaft which is positively coupled to the motor shaft. To verify the method of simulation, an American multiblade wind turbine is chosen, loaded by coupling to a centrifugal pump. Using the principle of conservation of energy and characteristics of both constituent units, two mathematical models are proposed: one for steady state operation and another for the transient state. The close comparison between the theoretical and the experimental results validates the proposed models and the method of simulation. The experimental method is described and the results of the experimental and theoretical investigation are presented.
Conformal loop quantum gravity coupled to the standard model
NASA Astrophysics Data System (ADS)
Campiglia, Miguel; Gambini, Rodolfo; Pullin, Jorge
2017-01-01
We argue that a conformally invariant extension of general relativity coupled to the standard model is the fundamental theory that needs to be quantized. We show that it can be treated by loop quantum gravity techniques. Through a gauge fixing and a modified Higgs mechanism particles acquire mass and one recovers general relativity coupled to the standard model. The theory suggests new views with respect to the definition of the Hamiltonian constraint in loop quantum gravity, the semi-classical limit and the issue of finite renormalization in quantum field theory in quantum space-time. It also gives hints about the elimination of ambiguities that arise in quantum field theory in quantum space-time in the calculation of back-reaction.
A parallel coupled oceanic-atmospheric general circulation model
Wehner, M.F.; Bourgeois, A.J.; Eltgroth, P.G.; Duffy, P.B.; Dannevik, W.P.
1994-12-01
The Climate Systems Modeling group at LLNL has developed a portable coupled oceanic-atmospheric general circulation model suitable for use on a variety of massively parallel (MPP) computers of the multiple instruction, multiple data (MIMD) class. The model is composed of parallel versions of the UCLA atmospheric general circulation model, the GFDL modular ocean model (MOM) and a dynamic sea ice model based on the Hiber formulation extracted from the OPYC ocean model. The strategy to achieve parallelism is twofold. One level of parallelism is accomplished by applying two dimensional domain decomposition techniques to each of the three constituent submodels. A second level of parallelism is attained by a concurrent execution of AGCM and OGCM/sea ice components on separate sets of processors. For this functional decomposition scheme, a flux coupling module has been written to calculate the heat, moisture and momentum fluxes independent of either the AGCM or the OGCM modules. The flux coupler`s other roles are to facilitate the transfer of data between subsystem components and processors via message passing techniques and to interpolate and aggregate between the possibly incommensurate meshes.
A parallel coupled oceanic-atmospheric general circulation model
NASA Astrophysics Data System (ADS)
Wehner, Michael F.; Bourgeois, Al J.; Eltgroth, Peter G.; Duffy, Phillip B.; Dannevik, William P.
1994-12-01
The Climate Systems Modeling group at Lawrence Liwermore National Laboratory (LLNL) has developed a portable coupled oceanic-atmospheric general circulation model suitable for use on a variety of massively parallel (MPP) computers of the multiple instruction, multiple data (MIMD) class. The model is composed of parallel versions of the UCLA atmospheric general circulation model, the GFDL modular ocean model (MOM) and a dynamic sea ice model based on the Hiber formulation extracted from the OPYC ocean model. The strategy to achieve parallelism is twofold. One level of parallelism is accomplished by applying two dimensional domain decomposition techniques to each of the three constituent submodels. A second level of parallelism is attained by a concurrent execution of AGCM and OGCM/sea ice components on separate sets of processors. For this functional decomposition scheme, a flux coupling module has been written to calculate the heat, moisture and momentum fluxes independent of either the AGCM or the OGCM modules. The flux coupler's other roles are to facilitate the transfer of data between subsystem components and processors via message passing techniques and to interpolate and aggregate between the possibly incommensurate meshes.
Assessing groundwater policy with coupled economic-groundwater hydrologic modeling
NASA Astrophysics Data System (ADS)
Mulligan, Kevin B.; Brown, Casey; Yang, Yi-Chen E.; Ahlfeld, David P.
2014-03-01
This study explores groundwater management policies and the effect of modeling assumptions on the projected performance of those policies. The study compares an optimal economic allocation for groundwater use subject to streamflow constraints, achieved by a central planner with perfect foresight, with a uniform tax on groundwater use and a uniform quota on groundwater use. The policies are compared with two modeling approaches, the Optimal Control Model (OCM) and the Multi-Agent System Simulation (MASS). The economic decision models are coupled with a physically based representation of the aquifer using a calibrated MODFLOW groundwater model. The results indicate that uniformly applied policies perform poorly when simulated with more realistic, heterogeneous, myopic, and self-interested agents. In particular, the effects of the physical heterogeneity of the basin and the agents undercut the perceived benefits of policy instruments assessed with simple, single-cell groundwater modeling. This study demonstrates the results of coupling realistic hydrogeology and human behavior models to assess groundwater management policies. The Republican River Basin, which overlies a portion of the Ogallala aquifer in the High Plains of the United States, is used as a case study for this analysis.
Coupled channel model of the scalar isovector meson photoproduction
NASA Astrophysics Data System (ADS)
Bibrzycki, Ł.; Kamiński, R.
2017-03-01
We present the coupled channel model of the scalar isovector resonance photoproduction including the πη, KK̅ and πη' channels and calculate resulting mass distribution and the cross section in the πη channel. We show that the shape of this mass distribution, is strongly affected by the phase of background amplitude. We also discuss the effect of inclusion the πη' channel on the overall isovector photoproduction process.
Eikonal solutions to optical model coupled-channel equations
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.; Khandelwal, Govind S.; Maung, Khin M.; Townsend, Lawrence W.; Wilson, John W.
1988-01-01
Methods of solution are presented for the Eikonal form of the nucleus-nucleus coupled-channel scattering amplitudes. Analytic solutions are obtained for the second-order optical potential for elastic scattering. A numerical comparison is made between the first and second order optical model solutions for elastic and inelastic scattering of H-1 and He-4 on C-12. The effects of bound-state excitations on total and reaction cross sections are also estimated.
Solvable model for chimera states of coupled oscillators.
Abrams, Daniel M; Mirollo, Rennie; Strogatz, Steven H; Wiley, Daniel A
2008-08-22
Networks of identical, symmetrically coupled oscillators can spontaneously split into synchronized and desynchronized subpopulations. Such chimera states were discovered in 2002, but are not well understood theoretically. Here we obtain the first exact results about the stability, dynamics, and bifurcations of chimera states by analyzing a minimal model consisting of two interacting populations of oscillators. Along with a completely synchronous state, the system displays stable chimeras, breathing chimeras, and saddle-node, Hopf, and homoclinic bifurcations of chimeras.
Multi-fluid simulation models for inductively coupled plasma sources
NASA Astrophysics Data System (ADS)
Kundrapu, Madhusudhan; Veitzer, Seth A.; Stoltz, Peter H.; Beckwith, Kristian R. C.; Smith, Jonathan
2017-08-01
A numerical simulation model for Inductively Coupled Plasma (ICP) sources and its implementation in the USim fluid-plasma software is presented. The electric field from the external antenna is solved using the vector potential equation with a variable dielectric constant. Plasma generation and species transport are solved using a set of collisional multi-fluid equations in diffusion form. USim results are benchmarked with experiments from the literature. Density and temperature distributions show good agreement both qualitatively and quantitatively with the measurements.
Reheating temperature in non-minimal derivative coupling model
Sadjadi, H. Mohseni; Goodarzi, Parviz E-mail: p_goodarzi@ut.ac.ir
2013-07-01
We consider the inflaton as a scalar field described by a non-minimal derivative coupling model with a power law potential. We study the slow roll inflation, the rapid oscillation phase, the radiation dominated and the recombination eras respectively, and estimate e-folds numbers during these epochs. Using these results and recent astrophysical data we determine the reheating temperature in terms of the spectral index and the amplitude of the power spectrum of scalar perturbations.
To study gaseous exchanges between the soil, biosphere and atmosphere, a biochemical model was coupled with the latest version of Meyers Multi-Layer Deposition Model. The biochemical model describes photosynthesis and respiration and their coupling with stomatal resistance for...
To study gaseous exchanges between the soil, biosphere and atmosphere, a biochemical model was coupled with the latest version of Meyers Multi-Layer Deposition Model. The biochemical model describes photosynthesis and respiration and their coupling with stomatal resistance for...
Validation model for the transient analysis of tightly coupled reactors
Bahadir, T.; Henry, A.F.
1996-12-31
Both the static and transient analysis of tightly coupled reactors differ from those of the loosely coupled systems. In these reactors, highly absorbing regions are interspaced with low absorbing regions. That raises questions of the acceptability of diffusion theory approximations. Also, the spectral shapes change drastically throughout the core and can be altered significantly by perturbations. Accurate analysis requires at least two-dimensional, multigroup transport methods. Although, such methods can be applied for static cases, for transient analysis they would be almost impossibly expensive. Recently a transient nodal model accounting for transport corrections has been developed for tightly coupled reactors. In this model, few-group, node-averaged cross sections and discontinuity factors are edited from full-core, higher order reference results such as Monte Carlo or fine-mesh, multigroup, discrete ordinate transport solutions for various conditions expected during transients. Tables of nodal parameters are constructed, and their values as the transient proceeds are found by interpolation. Although the static part of this few-group model can be tested easily by comparing nodal results with the reference transport solution, without a time-dependent transport code (at least a two-dimensional, multigroup, discrete ordinate code), doing the analogous validation for the time-dependent problem is not possible.
Strongly Coupled Models with a Higgs-like Boson
NASA Astrophysics Data System (ADS)
Pich, Antonio; Rosell, Ignasi; José Sanz-Cillero, Juan
2013-11-01
Considering the one-loop calculation of the oblique S and T parameters, we have presented a study of the viability of strongly-coupled scenarios of electroweak symmetry breaking with a light Higgs-like boson. The calculation has been done by using an effective Lagrangian, being short-distance constraints and dispersive relations the main ingredients of the estimation. Contrary to a widely spread believe, we have demonstrated that strongly coupled electroweak models with massive resonances are not in conflict with experimentalconstraints on these parameters and the recently observed Higgs-like resonance. So there is room for these models, but they are stringently constrained. The vector and axial-vector states should be heavy enough (with masses above the TeV scale), the mass splitting between them is highly preferred to be small and the Higgs-like scalar should have a WW coupling close to the Standard Model one. It is important to stress that these conclusions do not depend critically on the inclusion of the second Weinberg sum rule. We wish to thank the organizers of LHCP 2013 for the pleasant conference. This work has been supported in part by the Spanish Government and the European Commission [FPA2010-17747, FPA2011- 23778, AIC-D-2011-0818, SEV-2012-0249 (Severo Ochoa Program), CSD2007-00042 (Consolider Project CPAN)], the Generalitat Valenciana [PrometeoII/2013/007] and the Comunidad de Madrid [HEPHACOS S2009/ESP-1473].
A coupled multi-physics modeling framework for induced seismicity
NASA Astrophysics Data System (ADS)
Karra, S.; Dempsey, D. E.
2015-12-01
There is compelling evidence that moderate-magnitude seismicity in the central and eastern US is on the rise. Many of these earthquakes are attributable to anthropogenic injection of fluids into deep formations resulting in incidents where state regulators have even intervened. Earthquakes occur when a high-pressure fluid (water or CO2) enters a fault, reducing its resistance to shear failure and causing runaway sliding. However, induced seismicity does not manifest as a solitary event, but rather as a sequence of earthquakes evolving in time and space. Additionally, one needs to consider the changes in the permeability due to slip within a fault and the subsequent effects on fluid transport and pressure build-up. A modeling framework that addresses the complex two-way coupling between seismicity and fluid-flow is thus needed. In this work, a new parallel physics-based coupled framework for induced seismicity that couples the slip in faults and fluid flow is presented. The framework couples the highly parallel subsurface flow code PFLOTRAN (www.pflotran.org) and a fast Fourier transform based earthquake simulator QK3. Stresses in the fault are evaluated using Biot's formulation in PFLOTRAN and is used to calculate slip in QK3. Permeability is updated based on the slip in the fault which in turn influences flow. Application of the framework to synthetic examples and datasets from Colorado and Oklahoma will also be discussed.
Coupled chemical and diffusion model for compacted bentonite
Olin, M.; Lehikoinen, J.; Muurinen, A.
1995-12-31
A chemical equilibrium model has been developed for ion-exchange and to a limited extent for other reactions, such as precipitation or dissolution of calcite or gypsum, in compacted bentonite water systems. The model was successfully applied to some bentonite experiments, especially as far as monovalent ions were concerned. The fitted log-binding constants for the exchange of sodium for potassium, magnesium, and calcium were 0.27, 1.50, and 2.10, respectively. In addition, a coupled chemical and diffusion model has been developed to take account of diffusion in pore water, surface diffusion and ion-exchange.d the model was applied to the same experiments as the chemical equilibrium model, and its validation was found partly successful. The above values for binding constants were used also in the coupled model. The apparent (both for anions and cations) and surface diffusion (only for cations) constants yielding the best agreement between calculated and experimental data were 3.0 {times} 10{sup {minus}11} m{sup 2}/s and 6.0 {times} 10{sup {minus}12} m{sup 2}/s, respectively. These values are questionable, however, as experimental results good enough for fitting are currently not available.
A tree-parenchyma coupled model for lung ventilation simulation.
Pozin, N; Montesantos, S; Katz, I; Pichelin, M; Vignon-Clementel, I; Grandmont, C
2017-02-22
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 tracheo-bronchial 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 CT scans are considered. Realistic Dirichlet boundary conditions can be deduced from surface registration on CT 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.
Lagrangian Transport in a coupled Chemistry Climate Model
NASA Astrophysics Data System (ADS)
Hoppe, C.; Müller, R.; Günther, G.; Hoffmann, L.
2012-04-01
We describe the implementation of a Lagrangian transport core in a chemistry climate model (CCM). This is motivated by the problem that in many cases trace gas distributions in the stratosphere can not be represented properly in a classical Eulerian framework with a fixed model grid, especially in regions where strong trace gas gradients occur. Here, we focus on stratospheric water vapor, which is an important driver of surface climate change on decadal scales. In this case, the transport representation is particularly important in the tropical tropopause layer (TTL), where tropospheric air enters into the stratosphere, i.e. , where the entry level of stratospheric water vapor is determined. For this purpose, the Chemical Lagrangian Model of the Stratosphere (CLaMS) is coupled with the ECHAM/MESSy Atmospheric Chemistry Model (EMAC). The latter includes the ECHAM5 climate model, and a coupling interface, which allows for flexible coupling and switching between different submodels. The chemistry transport model CLaMS provides a full Lagrangian transport representation to calculate constituent transport on a set of air parcels that move along trajectories. In the Lagrangian frame of reference, different vertical velocity representations can be used to drive the trajectories: - kinematic transport in isobaric coordinates with omega as vertical velocity, - diabatic transport in isentropic coordinates, where thetadot calculated from diabatic heatingrates is used as vertical velocity. Since vertical winds in the statosphere derived with the kinematic method from the continuity equation often suffer from excessive numerical noise and errors, we expect that constituent transport using the diabatic method will improve the simulations of stratospheric water vapor. We will present preliminary results illustrating how the different transport representations influence simulated tracer distributions.
Gauge coupling unification in a classically scale invariant model
NASA Astrophysics Data System (ADS)
Haba, Naoyuki; Ishida, Hiroyuki; Takahashi, Ryo; Yamaguchi, Yuya
2016-02-01
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) C with masses lower than 1 TeV, and the SM singlet Majorana dark matter with mass lower than 2.6 TeV.
A Coupled Plasma-Sheath Model for High Density Sources
NASA Technical Reports Server (NTRS)
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.
A Fully Coupled Computational Model of the Silylation Process
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.
Warm stellar matter within the quark-meson-coupling model
NASA Astrophysics Data System (ADS)
Panda, P. K.; Providência, C.; Menezes, D. P.
2010-10-01
In the present article, we investigate stellar matter obtained within the quark-meson-coupling (QMC) model for fixed temperature and with the entropy of the order of 1 or 2 Boltzmann units per baryon for neutrino-free matter and matter with trapped neutrinos. A new prescription for the calculation of the baryon effective masses in terms of the free energy is used. Comparing the results of the present work with those obtained from the nonlinear Walecka model, smaller strangeness and neutrino fractions are predicted within QMC. As a consequence, QMC has a smaller window of metastability for conversion into a low-mass blackhole during cooling.
Warm stellar matter within the quark-meson-coupling model
Panda, P. K.; Providencia, C.; Menezes, D. P.
2010-10-15
In the present article, we investigate stellar matter obtained within the quark-meson-coupling (QMC) model for fixed temperature and with the entropy of the order of 1 or 2 Boltzmann units per baryon for neutrino-free matter and matter with trapped neutrinos. A new prescription for the calculation of the baryon effective masses in terms of the free energy is used. Comparing the results of the present work with those obtained from the nonlinear Walecka model, smaller strangeness and neutrino fractions are predicted within QMC. As a consequence, QMC has a smaller window of metastability for conversion into a low-mass blackhole during cooling.
Semi-active on-off damping control of a dynamic vibration absorber using Coriolis force
NASA Astrophysics Data System (ADS)
La, Viet Duc
2012-07-01
A passive dynamic vibration absorber (DVA) moving along a pendulum can cause the nonlinear Coriolis damping to reduce the pendulum swing. This paper proposes a simple semi-active on-off damping controller to improve the passive Coriolis DVA. The aim of the on-off damping control is to amplify the DVA resonance motion to increase the energy dissipated. Moreover, the paper finds the analytical solution of the harmonic vibration of semi-active controlled system. The accuracy of the analytical formulas and the superior performance of the semi-active DVA are verified by numerical simulations.
Classical Solutions to Semi-geostrophic System with Variable Coriolis Parameter
NASA Astrophysics Data System (ADS)
Cheng, Jingrui; Cullen, Michael; Feldman, Mikhail
2017-09-01
We prove the short time existence and uniqueness of smooth solutions (in {C^{k+2,α}} with {k ≥q 2} ) to the 2-D semi-geostrophic system and the semi-geostrophic shallow water system with variable Coriolis parameter f and periodic boundary conditions, under the natural convexity condition on the initial data. The dual space used in analysis of the semi-geostrophic system with constant f is not available for the variable Coriolis parameter case, and we develop a time-stepping procedure in Lagrangian coordinates in the physical space to overcome this difficulty.
A novel time varying signal processing method for Coriolis mass flowmeter.
Shen, Ting-Ao; Tu, Ya-Qing; Zhang, Hai-Tao
2014-06-01
The precision of frequency tracking method and phase difference calculation method affects the measurement precision of Coriolis Mass Flowmeter directly. To improve the accuracy of the mass flowrate, a novel signal processing method for Coriolis Mass Flowmeter is proposed for this time varying signal, which is comprised of a modified adaptive lattice notch filter and a revised sliding recursive discrete-time Fourier transform algorithm. The method cannot only track the change of frequency continuously, but also ensure the calculation accuracy when measuring phase difference. The computational load of the proposed method is small with higher accuracy. Simulation and experiment results show that the proposed method is effective.
A 3D fully coupled wave-current-sediment model
NASA Astrophysics Data System (ADS)
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)
Turner, John A; Allu, Srikanth; Berrill, Mark A; Elwasif, Wael R; Kalnaus, Sergiy; Kumar, Abhishek; Lebrun-Grandie, Damien T; Pannala, Dr. Sreekanth; Simunovic, Srdjan
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 a Thermodynamic Sea Ice Model with WRF
NASA Astrophysics Data System (ADS)
Krieger, J. R.; Zhang, J.
2009-12-01
Sea ice plays a significant role in shaping the atmospheric dynamics of the Arctic and surrounding regions through the modification of surface characteristics such as surface roughness, heat conductivity, and albedo. These in turn have both thermodynamic impacts on the surface heat budget and direct dynamic impacts on the low-level winds. In numerical atmospheric models, the accurate treatment of sea ice is therefore of critical importance in producing realistic simulations, not only on the global scale but at local and regional scales as well. However, sea ice is an often-neglected component of mesoscale meteorological models, many times being treated as just another land cover type without the sufficient complexity necessary to properly characterize its thermodynamic effects. To address this deficiency, we have recently coupled a thermodynamic sea ice model with the latest version of the Weather Research and Forecasting (WRF) model in order to improve the latter's simulation of sea ice surface temperatures, and by extension its simulation of Arctic conditions as a whole. A series of case studies was performed in which results from the coupled and unmodified versions of WRF were compared to determine the efficacy of this approach in improving weather simulations along the Beaufort and Chukchi Sea coasts in northern Alaska. In addition to surface station data, observations made as part of the SHEBA and SEDNA field campaigns and by two buoys recently deployed in the Beaufort Sea were used to verify the model output.
A global coupled model of the lithosphere and mantle dynamics
NASA Astrophysics Data System (ADS)
Iaffaldano, G.; Bunge, H.
2004-12-01
Understanding the dynamics of global lithospheric motion is one of the most important problems in geodynamics today. Mantle convection is commonly accepted as the driving force for plate motion but, while the kinematics of plate movement is well known from space geodetic and paleomagnetic observations, we lack a rigorous description of the coupled mantle convection-plate motion system. Here we present first results from a coupled mantle convection-global lithosphere motion model following a similar effort by Lithgow-Bertelloni and Guynn. Our plate motion code is SHELLS, a thinsheet FEM code developed by Bird which computes global plate motion and explicitly accounts for faults. The global mantle convection code is TERRA, a high-resolution 3-D FEM code developed and parallelized by Bunge and Baumgardner. We perform simple modeling experiments in which the shear tractions applied to the bottom of the lithosphere arise directly from the mantle circulation model. Our mantle circulation model includes a history of subduction and accounts, among others, for variations in mantle viscosity and strong bottom heating from the core. We find that our results are sensitive to the amount of core heating, an inference that has received renewed attention lately, and that models with stronger core heating overall are in better agreement with observations of intraplate stresses derived from the World Stress Map.
The dynamics of a coupled soilscape-landscape evolution model
NASA Astrophysics Data System (ADS)
Welivitiya, Dimuth; Willgoose, Garry; Hancock, Greg
2016-04-01
In this study we present results obtained from a landform evolution model coupled with SSSPAM5D soilscape evolution model. This presentation will show a number of computer animations with this coupled model using a range of widely accepted soil profile weathering models, and erosion/armouring models. The animations clearly show that subtle changes in process can result in dramatic changes in long-term equilibrium hillslope and soilscape form. We will discuss the reasons for these differences, arguing from the various mathematical and physical assumptions modelled, and infer how observed hillslope form may provide identifiable (and perhaps quantifiable) landform and soilscape signatures of landscape and soilscape process, and in particular the coupling between the landscape and the soilscape. Specifically we have simulated soilscapes using 3 depth dependent weathering functions: 1) Exponential, 2) Humped and 3) Reversed exponential. The Exponential weathering function simulates physical weathering due to thermal effects, and the weathering rate exponentially decreases with depth. The Humped function simulates chemical and/or physical weathering with moisture feedbacks, where the highest weathering rate is at a finite depth below the surface and exponentially declines with depth. The Reversed exponential function simulates chemical weathering, and the highest weathering rate is at the soil-saprolite interface and exponentially decreases both above and below the interface. Both the Humped and Reversed exponential functions can be used as approximations to chemical weathering as they can be derived analytically by solving widely accepted geochemical weathering equations. The Humped function can arise where the weathering fluid is introduced at the top of the soil profile (e.g. rainfall equilibrated with carbon dioxide in the atmosphere), while the Reversed exponential can be derived when carbon dioxide is generated within the profile (e.g. by biodegradation of soil
Fully coupled "online" chemistry within the WRF model
NASA Astrophysics Data System (ADS)
Grell, Georg A.; Peckham, Steven E.; Schmitz, Rainer; McKeen, Stuart A.; Frost, Gregory; Skamarock, William C.; Eder, Brian
A fully coupled "online" Weather Research and Forecasting/Chemistry (WRF/Chem) model has been developed. The air quality component of the model is fully consistent with the meteorological component; both components use the same transport scheme (mass and scalar preserving), the same grid (horizontal and vertical components), and the same physics schemes for subgrid-scale transport. The components also use the same timestep, hence no temporal interpolation is needed. The chemistry package consists of dry deposition ("flux-resistance" method), biogenic emission as in [Simpson et al., 1995. Journal of Geophysical Research 100D, 22875-22890; Guenther et al., 1994. Atmospheric Environment 28, 1197-1210], the chemical mechanism from RADM2, a complex photolysis scheme (Madronich scheme coupled with hydrometeors), and a state of the art aerosol module (MADE/SORGAM aerosol parameterization). The WRF/Chem model is statistically evaluated and compared to MM5/Chem and to detailed photochemical data collected during the summer 2002 NEAQS field study. It is shown that the WRF/Chem model is statistically better skilled in forecasting O 3 than MM5/Chem, with no appreciable differences between models in terms of bias with the observations. Furthermore, the WRF/Chem model consistently exhibits better skill at forecasting the O 3 precursors CO and NO y at all of the surface sites. However, the WRF/Chem model biases of these precursors and of other gas-phase species are persistently higher than for MM5/Chem, and are most often biased high compared to observations. Finally, we show that the impact of other basic model assumptions on these same statistics can be much larger than the differences caused by model differences. An example showing the sensitivity of various statistical measures with respect to the treatment of biogenic volatile organic compounds emissions illustrates this impact.
Upscalling processes in an ocean-atmosphere multiscale coupled model
NASA Astrophysics Data System (ADS)
Masson, S. G.; Berthet, S.; Samson, G.; Crétat, J.; Colas, F.; Echevin, V.; Jullien, S.; Hourdin, C.
2015-12-01
This work explores new pathways toward a better representation of the multi-scale physics that drive climate variability. We are analysing the key upscaling processes by which small-scale localized errors have a knock-on effect onto global climate. We focus on the Peru-Chilli coastal upwelling, an area known to hold among the strongest models biases in the Tropics. Our approach is based on the development of a multiscale coupling interface allowing us to couple WRF with the NEMO oceanic model in a configuration including 2-way nested zooms in the oceanic and/or the atmospheric component of the coupled model. Upscalling processes are evidenced and quantified by comparing three 20-year long simulations of a tropical channel (45°S-45°N), which differ by their horizontal resolution: 0.75° everywhere, 0.75°+0.25° zoom in the southeastern Pacific or 0.25° everywhere. This set of three 20-year long simulations was repeated with 3 different sets of parameterizations to assess the robustness of our results. Our results show that adding an embedded zoom over the southeastern Pacific only in the atmosphere cools down the SST along the Peru-Chili coast, which is a clear improvement. This change is associated with a displacement of the low-level cloud cover, which moves closer to the coast cooling further the coastal area SST. Offshore, we observe the opposite effect with a reduction of the cloud cover with higher resolution, which increases solar radiation and warms the SST. Increasing the resolution in the oceanic component show contrasting results according to the different set parameterization used in the experiments. Some experiment shows a coastal cooling as expected, whereas, in other cases, we observe a counterintuitive response with a warming of the coastal SST. Using at the same time an oceanic and an atmospheric zoom mostly combines the results obtained when using the 2-way nesting in only one component of the coupled model. In the best case, we archive by this
Model independent predictions for rare top decays with weak coupling
Datta, Alakabha; Duraisamy, Murugeswaran
2010-04-01
Measurements at B factories have provided important constraints on new physics in several rare processes involving the B meson. New physics, if present in the b quark sector may also affect the top sector. In an effective Lagrangian approach, we write down operators, where effects in the bottom and the top sector are related. Assuming the couplings of the operators to be of the same size as the weak coupling g of the standard model and taking into account constraints on new physics from the bottom sector as well as top branching ratios, we make predictions for the rare top decays t{yields}cV, where V={gamma}, Z. We find branching fractions for these decays within possible reach of the LHC. Predictions are also made for t{yields}sW.
Modeling a synthetic multicellular clock: Repressilators coupled by quorum sensing
Garcia-Ojalvo, Jordi; Elowitz, Michael B.; Strogatz, Steven H.
2004-01-01
Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators. PMID:15256602
Unified minimal supersymmetric model with large Yukawa couplings
Rattazzi, R.; Sarid, U.
1996-02-01
The consequences of assuming the third-generation Yukawa couplings are all large and comparable are studied in the context of the minimal sypersymmetric extension of the standard model. General aspects of the RG evolution of the parameters, theoretical constraints needed to ensure proper electroweak symmetry breaking, and experimental and cosmological bounds on low-energy parameters are presented. We also present complete and exact semianalytic solutions to the one-loop RG equations. Focusing on SU(5) or SO(10) unification, we analyze the relationship between the top and bottom masses and the superspectrum, and the phenomenological implications of the GUT conditions on scalar masses. Future experimental measurements of the superspectrum and of the strong coupling will distinguish between various GUT-scale scenarios. And if present experimental knowledge is to be accounted for most naturally, a particular set of predictions is singled out. {copyright} {ital 1996 The American Physical Society.}
Coupled Hydro-Mechanical Model of Bentonite Hydration and Swelling
NASA Astrophysics Data System (ADS)
Hancilova, Ilona; Hokr, Milan
2016-10-01
This paper deals with the modelling of coupled hydro-mechanical processes at the buffer and host rock interface (bentonite and granite) in the context of the safe disposal of spent nuclear fuel. Granite, as one of the barriers, includes fractures which are the source for hydration of bentonite and its subsequent swelling. It affects the mechanical behaviour and possibly the stability of the whole system. A non-linear solution for the stress-deformation problem with swelling was developed. This solution is coupled with the non-linear diffusion problem (for unsaturated flow). The swelling is defined using a coefficient dependent on water content according to literature data, with the effective Young's modulus decreasing close to zero corresponding to the plastic state. Results confirm the expected non-uniform saturation, swelling, and stresses in bentonite and small contribution to a fracture displacement.
Particle production within the quark meson coupling model
Panda, P. K.; Menezes, D. P.; Providencia, C.
2009-07-15
Quark-meson coupling (QMC) models can be successfully applied to the description of compact star properties in nuclear astrophysics as well as to nuclear matter. In the regime of hot hadronic matter very few calculations exist using the QMC model, in particular when applied to particle yields in heavy ion collisions. In the present work, we identify the free energy of the bag with the effective mass of the baryons and we calculate the particle production yields on a Au+Au collision at the BNL Relativistic Heavy Ion Collider (RHIC) with the QMC model and compare them with results obtained previously with other relativistic models. A smaller temperature for the fireball, T=132 MeV, is obtained because of the smaller effective baryon masses predicted by QMC. QMC was also applied to the description of particle yields at the CERN Super Proton Synchrotron (SPS) in Pb+Pb collisions.
Thermodynamics of the BMN matrix model at strong coupling
NASA Astrophysics Data System (ADS)
Costa, Miguel S.; Greenspan, Lauren; Penedones, João; Santos, Jorge E.
2015-03-01
We construct the black hole geometry dual to the deconfined phase of the BMN matrix model at strong 't Hooft coupling. We approach this solution from the limit of large temperature where it is approximately that of the non-extremal D0-brane geometry with a spherical S 8 horizon. This geometry preserves the SO(9) symmetry of the matrix model trivial vacuum. As the temperature decreases the horizon becomes deformed and breaks the SO(9) to the SO(6) × SO(3) symmetry of the matrix model. When the black hole free energy crosses zero the system undergoes a phase transition to the confined phase described by a Lin-Maldacena geometry. We determine this critical temperature, whose computation is also within reach of Monte Carlo simulations of the matrix model.
High-resolution reactive transport: A coupled parallel hydrogeochemical model
NASA Astrophysics Data System (ADS)
Beisman, J. J.; Maxwell, R. M.; Steefel, C. I.; Sitchler, A.; Molins, S.
2013-12-01
Subsurface hydrogeochemical systems are an especially complex component of the terrestrial environment and play host to a multitude of interactions. Parameterizations of these interactions are perhaps the least understood component of terrestrial systems, presenting uncertainties in the predictive understanding of biogeochemical cycling and transport. Thorough knowledge of biogeochemical transport processes is critical to the quantification of carbon/nutrient fluxes in the subsurface, and to the development of effective contaminant remediation techniques. Here we present a coupled parallel hydrogeochemical model, ParCrunchFlow, as a tool to further our understanding of governing processes and interactions in natural hydrogeochemical systems. ParCrunchFlow is a coupling of the reactive transport simulator CrunchFlow with the hydrologic model ParFlow. CrunchFlow is a multicomponent reactive flow and transport code that can be used to simulate a range of important processes and environments, including reactive contaminant transport, chemical weathering, carbon sequestration, biogeochemical cycling, and water-rock interaction. ParFlow is a parallel, three-dimensional, variably-saturated, coupled surface-subsurface flow and transport code with the ability to simulate complex topography, geology, and heterogeneity. ParCrunchflow takes advantage of the efficient parallelism built into Parflow, allowing the numerical simulation of reactive transport processes in chemically and physically heterogeneous media at high spatial resolutions. This model provides an ability to further examine the interactions and feedbacks between biogeochemical systems and complex subsurface flow fields. In addition to the details of model construction, results will be presented that show floodplain nutrient cycling and the effects of heterogeneity on small-scale mixing reactions at the Department of Energy's Old Rifle Legacy site.
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...
A fully coupled thermal, chemical, mechanical cookoff model
Hobbs, M.L.; Baer, M.R.; Gross, R.J.
1994-05-01
Cookoff modeling of confined energetic materials involves the coupling of thermal, chemical and mechanical effects. In the past, modeling has focussed on the prediction of thermal runaway with little regard to the effects of mechanical behavior of the energetic material. To address the mechanical response of the energetic material, a constitutive submodel has been developed which can be incorporated into thermal-chemical-mechanical analysis. This work presents development of this submodel and its incorporation into a fully coupled one-dimensional, thermal-chemical-mechanical computer code to simulate thermal initiation of energetic materials. Model predictions include temperature, chemical species, stress, strain, solid/gas pressure, solid/gas density, yield function, and gas volume fraction. Sample results from a scaled aluminum tube filled with RDX exposed to a constant temperature bath at 500 K will be displayed. The micromechanical submodel is based on bubble mechanics which describes nucleation, decomposition, and elastic/plastic mechanical behavior. This constitutive material description requires input of temperatures and reacted fraction of the energetic material as provided by the reactive heat flow code, XCHEM, and the mechanical response is predicted using a quasistatic mechanics code, SANTOS. A parametric sensitivity analysis indicates that a small degree of decomposition causes significant pressurization of the energetic material, which implies that cookoff modeling must consider the strong interaction between thermal-chemistry and mechanics. This document consists of view graphs from the poster session.
Coupling the Earth's Rotational and Gravito-Inertial Modes
NASA Astrophysics Data System (ADS)
Triana, S. A.; Rekier, J.; Trinh, A.; Laguerre, R.; Dehant, V. M. A.; Zhu, P.
2016-12-01
Wave motions in the Earth's fluid core, supported by the restoring action of both buoyancy (within the stably stratified top layer) and the Coriolis force, lead to the existence of global oscillation modes, the so-called gravito-inertial modes. These fluid modes can couple with the rotational modes of the Earth by exerting torques on the mantle and the inner core. Viscous shear stresses at the fluid boundaries, along with pressure and gravitation, contribute to the overall torque balance. Previous research by Rogister & Valette (2009) suggests that indeed rotational and gravito-inertial modes are coupled, thus shifting the frequencies of the Chandler Wobble (CW), the Free Core Nutation (FCN) and the Free Inner Core Nutation (FICN). Here we outline a plan to develop a more accurate numerical model of the Earth's fluid core by considering a generalised eigenvalue problem that solves simultaneously the Liouville equation for the rotational modes, and the Navier-Stokes equation for the inertial modes.
Biomass assimilation in coupled ecohydrodynamical model of the Mediterranean Sea
NASA Astrophysics Data System (ADS)
Crispi, G.; Bournaski, E.; Crise, A.
2003-04-01
Data assimilation has raised new interest in the last years in the context of the environmental sciences. The swift increment of the attention paid to it in oceanography is due to the coming age of operational services for the marine environment which is going to dramatically increase the demand for accurate, timely and reliable estimates of the space and time distribution both for physical and in a near future for biogeochemical fields. Data assimilation combines information derived from measurements with knowledge of the rules that govern the evolution of the system of interest through formalization and implementation in numerical models. The importance of ocean data assimilation has been recognized by several international programmes as JGOFS, GOOS and CLIVAR. This work presents an eco-hydrodynamic model of the Mediterranean Sea developed at the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS, Trieste, Italy. It includes 3-D MOM-based hydrodynamics of the Mediterranean Sea, coupled with biochemical model of Nitrogen, Phytoplankton, Zooplankton, and Detritus (NPZD). Monthly mean wind forcings are adopted to force this MOM-NPZD model. For better prediction and analysis of N, P, Z and D distributions in the sea the model needs data assimilation from biomass observations on the sea surface. Chosen approach for evaluating performances of data assimilation techniques in coupled model is the definition of a twin experiment testbed where a reference run is carried out assuming its result as the truth. We define a sampling strategy to obtain different datasets to be incorporated in another ecological model in successive runs in order to appraise the potential of the data assimilation and sampling strategy. The runs carried out with different techniques and different spatio-temporal coverages are compared in order to evaluate the sensitivity to different coverage of dataset. The discussed alternative way is to assume the ecosystem at steady state and
NASA Technical Reports Server (NTRS)
Pigeon, Pascale; Bortolami, Simone B.; DiZio, Paul; Lackner, James R.
2003-01-01
rotation, the finger movement generally occurred entirely during the trunk movement, indicating that the CNS did not minimize Coriolis forces incumbent on trunk rotation by sequencing the arm and trunk motions into a turn followed by a reach. A simplified model of the arm/trunk system revealed that additional interaction torques generated on the arm during voluntary turning and reaching were equivalent to < or =1.8 g (1 g = 9.81 m/s(2)) of external force at the elbow but did not degrade performance. In slow-rotation room studies involving reaching movements during passive rotation, Coriolis forces as small as 0.2 g greatly deflect movement trajectories and endpoints. We conclude that compensatory motor innervations are engaged in a predictive fashion to counteract impending self-generated interaction torques during voluntary reaching movements.
NASA Technical Reports Server (NTRS)
Pigeon, Pascale; Bortolami, Simone B.; DiZio, Paul; Lackner, James R.
2003-01-01
rotation, the finger movement generally occurred entirely during the trunk movement, indicating that the CNS did not minimize Coriolis forces incumbent on trunk rotation by sequencing the arm and trunk motions into a turn followed by a reach. A simplified model of the arm/trunk system revealed that additional interaction torques generated on the arm during voluntary turning and reaching were equivalent to < or =1.8 g (1 g = 9.81 m/s(2)) of external force at the elbow but did not degrade performance. In slow-rotation room studies involving reaching movements during passive rotation, Coriolis forces as small as 0.2 g greatly deflect movement trajectories and endpoints. We conclude that compensatory motor innervations are engaged in a predictive fashion to counteract impending self-generated interaction torques during voluntary reaching movements.
Pigeon, Pascale; Bortolami, Simone B; DiZio, Paul; Lackner, James R
2003-01-01
rotation, the finger movement generally occurred entirely during the trunk movement, indicating that the CNS did not minimize Coriolis forces incumbent on trunk rotation by sequencing the arm and trunk motions into a turn followed by a reach. A simplified model of the arm/trunk system revealed that additional interaction torques generated on the arm during voluntary turning and reaching were equivalent to < or =1.8 g (1 g = 9.81 m/s(2)) of external force at the elbow but did not degrade performance. In slow-rotation room studies involving reaching movements during passive rotation, Coriolis forces as small as 0.2 g greatly deflect movement trajectories and endpoints. We conclude that compensatory motor innervations are engaged in a predictive fashion to counteract impending self-generated interaction torques during voluntary reaching movements.
Status of the seamless coupled modelling system ICON-ART
NASA Astrophysics Data System (ADS)
Vogel, Bernhard; Rieger, Daniel; Schroeter, Jenniffer; Bischoff-Gauss, Inge; Deetz, Konrad; Eckstein, Johannes; Foerstner, Jochen; Gasch, Philipp; Ruhnke, Roland; Vogel, Heike; Walter, Carolin; Weimer, Michael
2016-04-01
The integrated modelling framework ICON-ART [1] (ICOsahedral Nonhydrostatic - Aerosols and Reactive Trace gases) extends the numerical weather prediction modelling system ICON by modules for gas phase chemistry, aerosol dynamics and related feedback processes. The nonhydrostatic global modelling system ICON [2] is a joint development of German Weather Service (DWD) and Max Planck Institute for Meteorology (MPI-M) with local grid refinement down to grid sizes of a few kilometers. It will be used for numerical weather prediction, climate projections and for research purposes. Since January 2016 ICON runs operationally at DWD for weather forecast on the global scale with a grid size of 13 km. Analogous to its predecessor COSMO-ART [3], ICON-ART is designed to account for feedback processes between meteorological variables and atmospheric trace substances. Up to now, ICON-ART contains the dispersion of volcanic ash, radioactive tracers, sea salt aerosol, as well as ozone-depleting stratospheric trace substances [1]. Recently, we have extended ICON-ART by a mineral dust emission scheme with global applicability and nucleation parameterizations which allow the cloud microphysics to explicitly account for prognostic aerosol distributions. Also very recently an emission scheme for volatile organic compounds was included. We present first results of the impact of natural aerosol (i.e. sea salt aerosol and mineral dust) on cloud properties and precipitation as well as the interaction of primary emitted particles with radiation. Ongoing developments are the coupling with a radiation scheme to calculate the photolysis frequencies, a coupling with the RADMKA (1) chemistry and first steps to include isotopologues of water. Examples showing the capabilities of the model system will be presented. This includes a simulation of the transport of ozone depleting short-lived trace gases from the surface into the stratosphere as well as of long-lived tracers. [1] Rieger, D., et al
Computational Implementation of a Coupled Plasma-Neutral Fluid Model
NASA Astrophysics Data System (ADS)
Vold, E. L.; Najmabadi, F.; Conn, R. W.
1992-12-01
This paper describes the computational transport of coupled plasma-neutral fluids in the edge region of a toroidally symmetric magnetic confinement device, with applications to the tokamak. The model couples neutral density in a diffusion approximation with a set of transport equations for the plasma including density, classical plasma parallel velocity, anomalous cross-field velocity, and ion and electron temperature equations. The plasma potential, gradient electric fields, drift velocity, and net poloidal velocity are computed as dependent quantities under the assumption of ambipolarity. The implementation is flexible to permit extension in the future to a fully coupled set of non-ambipolar momentum equations. The computational method incorporates sonic flow and particle recycling of ions and neutrals at the vessel boundary. A numerically generated orthogonal grid conforms to the poloidal magnetic flux surfaces. Power law differencing based on the SIMPLE relaxation method is modified to accomodate the compressible reactive plasma flow with a "semi-implicit" diffusion method. Residual corrections are applied to obtain a valid convergence to the steady state solution. Results are presented for a representative divertor tokamak in a high recycling regime, showing strongly peaked neutral and plasma densities near the divertor target. Solutions show large poloidal and radial gradients in the plasma density, potential, and temperatures. These findings may help to understand the strong turbulence experimentally observed in the plasma edge region of the tokamak.
Hyperon stars in a modified quark meson coupling model
NASA Astrophysics Data System (ADS)
Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.
2016-09-01
We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. The effect of a nonlinear ω -ρ term on the EOS is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of 2 M⊙ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear ω -ρ term in the context of obtaining the star mass constraint in the present set of parametrizations.
Optimizing phonon space in the phonon-coupling model
NASA Astrophysics Data System (ADS)
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
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
NASA Astrophysics Data System (ADS)
Pahar, Gourabananda; Dhar, Anirban
2017-04-01
A coupled solenoidal Incompressible Smoothed Particle Hydrodynamics (ISPH) model is presented for simulation of sediment displacement in erodible bed. The coupled framework consists of two separate incompressible modules: (a) granular module, (b) fluid module. The granular module considers a friction based rheology model to calculate deviatoric stress components from pressure. The module is validated for Bagnold flow profile and two standardized test cases of sediment avalanching. The fluid module resolves fluid flow inside and outside porous domain. An interaction force pair containing fluid pressure, viscous term and drag force acts as a bridge between two different flow modules. The coupled model is validated against three dambreak flow cases with different initial conditions of movable bed. The simulated results are in good agreement with experimental data. A demonstrative case considering effect of granular column failure under full/partial submergence highlights the capability of the coupled model for application in generalized scenario.
Xie, L.; Pietrafesa, L.J.; Raman, S.
1997-03-18
Interactions between surface winds and ocean currents over an east-coast continental shelf are studied using a simple mathematical model. The model physics include cross-shelf advection of sea surface temperature (SST) by Ekman drift, upwelling due to Ekman transport divergence, differential heating of the low-level atmosphere by a cross-shelf SST gradient, and the Coriolis effect. Additionally, the effects of diabatic cooling of surface waters due to air-sea heat exchange and of the vertical density stratification on the thickness of the upper ocean Ekman layer are considered. The model results are qualitatively consistent with observed wind-driven coastal ocean circulation and surface wind signatures induced by SST. This simple model also demonstrates that two-way air-sea interaction plays a significant role in the subtidal frequency variability of coastal ocean circulation and mesoscale variability of surface wind fields over coastal waters.
Strong-coupling BCS models of Josephson qubits.
Alicki, R; Miklaszewski, W
2013-01-23
The strong-coupling version of the BCS theory for superconductors is used to derive microscopic models for all types of small Josephson junctions--charge qubit, flux qubit and phase qubit. Applied to Josephson qubits it yields a more complicated structure of the lowest-lying energy levels than that obtained from phenomenological models based on quantization of the Kirchhoff equations. In particular, highly degenerate levels emerge, which act as probability sinks for the qubit. The alternative formulae concerning spectra of superconducting qubits are presented and compared with the experimental data. In contrast to the existing theories those formulae contain microscopic parameters of the model. In particular, for the first time, the density of Cooper pairs at zero temperature is estimated for an Al-based flux qubit. Finally, the question whether small Josephson junctions can be treated as macroscopic quantum systems is briefly discussed.
Computational model for amoeboid motion: Coupling membrane and cytosol dynamics.
Moure, Adrian; Gomez, Hector
2016-10-01
A distinguishing feature of amoeboid motion is that the migrating cell undergoes large deformations, caused by the emergence and retraction of actin-rich protrusions, called pseudopods. Here, we propose a cell motility model that represents pseudopod dynamics, as well as its interaction with membrane signaling molecules. The model accounts for internal and external forces, such as protrusion, contraction, adhesion, surface tension, or those arising from cell-obstacle contacts. By coupling the membrane and cytosol interactions we are able to reproduce a realistic picture of amoeboid motion. The model results are in quantitative agreement with experiments and show how cells may take advantage of the geometry of their microenvironment to migrate more efficiently.
Computational model for amoeboid motion: Coupling membrane and cytosol dynamics
NASA Astrophysics Data System (ADS)
Moure, Adrian; Gomez, Hector
2016-10-01
A distinguishing feature of amoeboid motion is that the migrating cell undergoes large deformations, caused by the emergence and retraction of actin-rich protrusions, called pseudopods. Here, we propose a cell motility model that represents pseudopod dynamics, as well as its interaction with membrane signaling molecules. The model accounts for internal and external forces, such as protrusion, contraction, adhesion, surface tension, or those arising from cell-obstacle contacts. By coupling the membrane and cytosol interactions we are able to reproduce a realistic picture of amoeboid motion. The model results are in quantitative agreement with experiments and show how cells may take advantage of the geometry of their microenvironment to migrate more efficiently.
Modelling small-patterned neuronal networks coupled to microelectrode arrays
NASA Astrophysics Data System (ADS)
Massobrio, Paolo; Martinoia, Sergio
2008-09-01
Cultured neurons coupled to planar substrates which exhibit 'well-defined' two-dimensional network architectures can provide valuable insights into cell-to-cell communication, network dynamics versus topology, and basic mechanisms of synaptic plasticity and learning. In the literature several approaches were presented to drive neuronal growth, such as surface modification by silane chemistry, photolithographic techniques, microcontact printing, microfluidic channel flow patterning, microdrop patterning, etc. This work presents a computational model fit for reproducing and explaining the dynamics exhibited by small-patterned neuronal networks coupled to microelectrode arrays (MEAs). The model is based on the concept of meta-neuron, i.e., a small spatially confined number of actual neurons which perform single macroscopic functions. Each meta-neuron is characterized by a detailed morphology, and the membrane channels are modelled by simple Hodgkin-Huxley and passive kinetics. The two main findings that emerge from the simulations can be summarized as follows: (i) the increasing complexity of meta-neuron morphology reflects the variations of the network dynamics as a function of network development; (ii) the dynamics displayed by the patterned neuronal networks considered can be explained by hypothesizing the presence of several short- and a few long-term distance interactions among small assemblies of neurons (i.e., meta-neurons).
Modelling of strongly coupled particle growth and aggregation
NASA Astrophysics Data System (ADS)
Gruy, F.; Touboul, E.
2013-02-01
The mathematical modelling of the dynamics of particle suspension is based on the population balance equation (PBE). PBE is an integro-differential equation for the population density that is a function of time t, space coordinates and internal parameters. Usually, the particle is characterized by a unique parameter, e.g. the matter volume v. PBE consists of several terms: for instance, the growth rate and the aggregation rate. So, the growth rate is a function of v and t. In classical modelling, the growth and the aggregation are independently considered, i.e. they are not coupled. However, current applications occur where the growth and the aggregation are coupled, i.e. the change of the particle volume with time is depending on its initial value v0, that in turn is related to an aggregation event. As a consequence, the dynamics of the suspension does not obey the classical Von Smoluchowski equation. This paper revisits this problem by proposing a new modelling by using a bivariate PBE (with two internal variables: v and v0) and by solving the PBE by means of a numerical method and Monte Carlo simulations. This is applied to a physicochemical system with a simple growth law and a constant aggregation kernel.
Modelling small-patterned neuronal networks coupled to microelectrode arrays.
Massobrio, Paolo; Martinoia, Sergio
2008-09-01
Cultured neurons coupled to planar substrates which exhibit 'well-defined' two-dimensional network architectures can provide valuable insights into cell-to-cell communication, network dynamics versus topology, and basic mechanisms of synaptic plasticity and learning. In the literature several approaches were presented to drive neuronal growth, such as surface modification by silane chemistry, photolithographic techniques, microcontact printing, microfluidic channel flow patterning, microdrop patterning, etc. This work presents a computational model fit for reproducing and explaining the dynamics exhibited by small-patterned neuronal networks coupled to microelectrode arrays (MEAs). The model is based on the concept of meta-neuron, i.e., a small spatially confined number of actual neurons which perform single macroscopic functions. Each meta-neuron is characterized by a detailed morphology, and the membrane channels are modelled by simple Hodgkin-Huxley and passive kinetics. The two main findings that emerge from the simulations can be summarized as follows: (i) the increasing complexity of meta-neuron morphology reflects the variations of the network dynamics as a function of network development; (ii) the dynamics displayed by the patterned neuronal networks considered can be explained by hypothesizing the presence of several short- and a few long-term distance interactions among small assemblies of neurons (i.e., meta-neurons).
Model for a transformer-coupled toroidal plasma source
Rauf, Shahid; Balakrishna, Ajit; Chen Zhigang; Collins, Ken
2012-01-15
A two-dimensional fluid plasma model for a transformer-coupled toroidal plasma source is described. Ferrites are used in this device to improve the electromagnetic coupling between the primary coils carrying radio frequency (rf) current and a secondary plasma loop. Appropriate components of the Maxwell equations are solved to determine the electromagnetic fields and electron power deposition in the model. The effect of gas flow on species transport is also considered. The model is applied to 1 Torr Ar/NH{sub 3} plasma in this article. Rf electric field lines form a loop in the vacuum chamber and generate a plasma ring. Due to rapid dissociation of NH{sub 3}, NH{sub x}{sup +} ions are more prevalent near the gas inlet and Ar{sup +} ions are the dominant ions farther downstream. NH{sub 3} and its by-products rapidly dissociate into small fragments as the gas flows through the plasma. With increasing source power, NH{sub 3} dissociates more readily and NH{sub x}{sup +} ions are more tightly confined near the gas inlet. Gas flow rate significantly influences the plasma characteristics. With increasing gas flow rate, NH{sub 3} dissociation occurs farther from the gas inlet in regions with higher electron density. Consequently, more NH{sub 4}{sup +} ions are produced and dissociation by-products have higher concentrations near the outlet.
Global Magnetospheric Simulations: coupling with ionospheric and solar wind models
NASA Astrophysics Data System (ADS)
Lapenta, Giovanni; Olshevskyi, Vyacheslav; Amaya, Jorge; Deca, Jan; Markidis, Stefano; Vapirev, Alexander
2013-04-01
We present results on the global fully kinetic model of the magnetosphere of the Earth. The simulations are based on the iPic3D code [1] that treats kinetically all plasma species solving implicitly the equations of motion for electrons and ions, coupled with the Maxwell equations. We present results of our simulations and discuss the coupling at the inner boundary near the Earth with models of the ionosphere and at the outer boundary with models of the arriving solar wind. The results are part of the activities of the Swiff FP7 project: www.swiff.eu [1] Stefano Markidis, Giovanni Lapenta, Rizwan-uddin, Multi-scale simulations of plasma with iPIC3D, Mathematics and Computers in Simulation, Volume 80, Issue 7, March 2010, Pages 1509-1519, ISSN 0378-4754, 10.1016/j.matcom.2009.08.038 [2] Giovanni Lapenta, Particle simulations of space weather, Journal of Computational Physics, Volume 231, Issue 3, 1 February 2012, Pages 795-821, ISSN 0021-9991, 10.1016/j.jcp.2011.03.035.
Fluid Modeling of a Very High Frequency Capacitively Coupled Reactor
NASA Astrophysics Data System (ADS)
Upadhyay, Rochan; Raja, Laxminarayan; Ventzek, Peter; Iwao, Toshihiko; Ishibashi, Kiyotaka; Esgee Technologies Inc. Collaboration; University of Texas at Austin Collaboration; Tokyo Electron Ltd. Collaboration
2016-09-01
Very High Frequency Capacitively Coupled Plasma (VHF-CCP) discharges have been studied extensively for semiconductor manufacturing applications for well over a decade. Modeling of these discharges however poses significant challenges owing to complexity associated with simulation of multiple coupled phenomena (electro-static/magnetic fields and plasma physics) over different scales and the representation of these phenomena in a computational framework. We present 2D simulations of a self-consistent plasma with the electromagnetic field represented using vector and scalar potentials. For a range of operating conditions, the ratio of capacitive and inductive power, calculated using empirical correlations available in the literature, are matched by adjusting both the electrostatic and electromagnetic fields in a decoupled manner. We present results using this model that demonstrate most of the important VHF-CCP discharge phenomena reported in the literature, such as electromagnetic wave versus electrostatic heating and its impact on plasma non-uniformity, wave resonances, etc. while realizing a practically feasible computational model.
Model Organisms in G Protein–Coupled Receptor Research
Barr, Maureen M.; Bruchas, Michael R.; Ewer, John; Griffith, Leslie C.; Maiellaro, Isabella; Taghert, Paul H.; White, Benjamin H.
2015-01-01
The study of G protein–coupled receptors (GPCRs) has benefited greatly from experimental approaches that interrogate their functions in controlled, artificial environments. Working in vitro, GPCR receptorologists discovered the basic biologic mechanisms by which GPCRs operate, including their eponymous capacity to couple to G proteins; their molecular makeup, including the famed serpentine transmembrane unit; and ultimately, their three-dimensional structure. Although the insights gained from working outside the native environments of GPCRs have allowed for the collection of low-noise data, such approaches cannot directly address a receptor’s native (in vivo) functions. An in vivo approach can complement the rigor of in vitro approaches: as studied in model organisms, it imposes physiologic constraints on receptor action and thus allows investigators to deduce the most salient features of receptor function. Here, we briefly discuss specific examples in which model organisms have successfully contributed to the elucidation of signals controlled through GPCRs and other surface receptor systems. We list recent examples that have served either in the initial discovery of GPCR signaling concepts or in their fuller definition. Furthermore, we selectively highlight experimental advantages, shortcomings, and tools of each model organism. PMID:25979002
Hypernuclei in the quark-meson coupling model
K. Tsushima, P. A. M. Guichon
2010-07-01
We present results of hypernuclei calculated in the latest quark-meson coupling (QMC) model, where the effect of the mean scalar field in-medium on the one-gluon exchange hyperfine interaction, is also included self-consistently. The extra repulsion associated with this increased hyperfine interaction in-medium completely changes the predictions for {\\Sigma} hypernuclei. Whereas in the earlier version of QMC they were bound by an amount similar to {\\Lambda} hypernuclei, they are unbound in the latest version of QMC, in qualitative agreement with the experimental absence of such states.
Thermal modeling of absorber-coupled TES polarimeter.
Wang, G.; Yefremenko, V.; Datesman, A.; Novosad, V.; Pearson, J.; Shustakova, G.; Divan, R.; Lee, J.; Chang, C. L.; McMahon, J.; Bleem, L.; Crites, A. T,; Downes, T.; Mehl, J.; Everett, W.; Meyer, S. S.; Carlstrom, J. E.; Sayer, J.; Ruhl, J.; Univ. of Chicago; Case Western Reserve Univ.; B. Verkin Inst. Low Tempemperature and Physcial Engineering
2009-01-01
Using experimental thermal conductivity and volume heat capacity of narrow silicon nitride beams obtained from thermal test structures and a boundary limited phonon scattering model, as well as the heat conduction equation, we analyze the thermal performance of an absorber-coupled TES polarimeter with finite element method. The polarimeter's temperature distribution, thermal power readout efficiency, and time constant are calculated. The thermal power readout efficiency of the polarimeter is up to 87% at a low signal modulation frequency, and has a 0.5 dB attenuation at 120 Hz. We also compare a preliminary optical testing result with theoretical expectation.
Coupled atmosphere-ocean models of Titan's past
NASA Technical Reports Server (NTRS)
Mckay, Christopher P.; Pollack, James B.; Lunine, Jonathan I.; Courtin, Regis
1993-01-01
The behavior and possible past evolution of fully coupled atmosphere and ocean model of Titan are investigated. It is found that Titan's surface temperature was about 20 K cooler at 4 Gyr ago and will be about 5 K warmer 0.5 Gyr in the future. The change in solar luminosity and the conversion of oceanic CH4 to C2H6 drive the evolution of the ocean and atmosphere over time. Titan appears to have experienced a frozen epoch about 3 Gyr ago independent of whether an ocean is present or not. This finding may have important implications for understanding the inventory of Titan's volatile compounds.
Coupled atmosphere-ocean models of Titan's past
NASA Astrophysics Data System (ADS)
McKay, C. P.; Pollack, J. B.; Lunine, J. I.; Courtin, R.
1993-03-01
The behavior and possible past evolution of fully coupled atmosphere and ocean model of Titan are investigated. It is found that Titan's surface temperature was about 20 K cooler at 4 Gyr ago and will be about 5 K warmer 0.5 Gyr in the future. The change in solar luminosity and the conversion of oceanic CH4 to C2H6 drive the evolution of the ocean and atmosphere over time. Titan appears to have experienced a frozen epoch about 3 Gyr ago independent of whether an ocean is present or not. This finding may have important implications for understanding the inventory of Titan's volatile compounds.
Drift dynamics in a coupled model initialized for decadal forecasts
NASA Astrophysics Data System (ADS)
Sanchez-Gomez, Emilia; Cassou, Christophe; Ruprich-Robert, Yohan; Fernandez, Elodie; Terray, Laurent
2016-03-01
Drifts are always present in models when initialized from observed conditions because of intrinsic model errors; those potentially affect any type of climate predictions based on numerical experiments. Model drifts are usually removed through more or less sophisticated techniques for skill assessment, but they are rarely analysed. In this study, we provide a detailed physical and dynamical description of the drifts in the CNRM-CM5 coupled model using a set of decadal retrospective forecasts produced within CMIP5. The scope of the paper is to give some physical insights and lines of approach to, on one hand, implement more appropriate techniques of initialisation that minimize the drift in forecast mode, and on the other hand, eventually reduce the systematic biases of the models. We first document a novel protocol for ocean initialization adopted by the CNRM-CERFACS group for forecasting purpose in CMIP5. Initial states for starting dates of the predictions are obtained from a preliminary integration of the coupled model where full-field ocean surface temperature and salinity are restored everywhere to observations through flux derivative terms and full-field subsurface fields (below the prognostic ocean mixed layer) are nudged towards NEMOVAR reanalyses. Nudging is applied only outside the 15°S-15°N band allowing for dynamical balance between the depth and tilt of the tropical thermocline and the model intrinsic biased wind. A sensitivity experiment to the latitudinal extension of no-nudging zone (1°S-1°N instead of 15°, hereafter referred to as NOEQ) has been carried out. In this paper, we concentrate our analyses on two specific regions: the tropical Pacific and the North Atlantic basins. In the Pacific, we show that the first year of the forecasts is characterized by a quasi-systematic excitation of El Niño-Southern Oscillation (ENSO) warm events whatever the starting dates. This, through ocean-to-atmosphere heat transfer materialized by diabatic heating
ERIC Educational Resources Information Center
DiSpezio, Michael A.
2011-01-01
This article addresses misconceptions surrounding the Coriolis force and describes how it should be presented as a function within inertial and noninertial frames of reference. Not only does this demonstrate the nature of science as it strives to best interpret the natural world (and presents alternative explanations), but it offers a rich…
ERIC Educational Resources Information Center
DiSpezio, Michael A.
2011-01-01
This article addresses misconceptions surrounding the Coriolis force and describes how it should be presented as a function within inertial and noninertial frames of reference. Not only does this demonstrate the nature of science as it strives to best interpret the natural world (and presents alternative explanations), but it offers a rich…
Mode competition and destabilization of microfluidic channel flows by the Coriolis force
NASA Astrophysics Data System (ADS)
Sengupta, Saunak; Saha, Sandeep; Chakraborty, Suman
2016-11-01
Understanding flow stability in inertial microfluidics is very important due to its increased application in medical and chemical engineering. On a steady rotating platform centrifugal actuation drives fluid flow but Coriolis force can destabilize the flow and enhance mixing in a short span. We investigate the role of Coriolis force in micro-mixing and the structure of the roll-cells formed in rotating channel flow using linear stability theory. We conduct a parametric study at different rotation numbers, Reynolds number, axial and spanwise wavenumbers. Our results reveal existence of multiple competing unstable modes (Types I to IV) due to Coriolis force: Types I and II have been reported in literature and are responsible for the formation of evenly-spaced roll-cells. We find new instabilities (Types III and IV) which contribute to the formation of twisted roll cells. The existence of the instabilities is clearly demarcated on a regime map to assist future experiments to identify them. The kinetic energy budget has been analyzed to gain insight into the mechanism of energy transfer by Coriolis force from the mean flow to the perturbations. We make a qualitative comparison of roll-cells predicted by linear stability with previously reported experiments.
The influence of Coriolis forces on gyroscopic motion of spinning blades
NASA Technical Reports Server (NTRS)
Sisto, F.; Chang, A.; Sutcu, M.
1982-01-01
Turbomachine blades on spinning and precessing rotors experience gyroscopically induced instabilities and forcing. With vehicle-mounted turbomachines, either constant or harmonic precession occurs, depending on vehicle or mount motion. Responses of uniform cantilever beams at arbitrary stagger, subjected to the noted rotor motion, are predicted in both self-excited and forced-excitation modes taking into account Coriolis acceleration.
Geostrophic balance with a full Coriolis Force: implications for low latitutde studies
NASA Technical Reports Server (NTRS)
Juarez, M. de la Torre
2002-01-01
In its standard form, geostrophic balance uses a partial representation of the Coriolis force. The resulting formation has a singularity at the equator, and violates mass and momentum conservation. When the horizontal projection of the planetary rotation vector is considered, the singularity at the equator disappears, continuity can be preserved, and quasigeostrophy can be formulated at planetary scale.
Modeling G Protein-Coupled Receptors: a Concrete Possibility.
Costanzi, Stefano
2010-01-01
G protein-coupled receptors (GPCRs) are a large superfamily of membrane bound signaling proteins that are involved in the regulation of a wide range of physiological functions and constitute the most common target for therapeutic intervention. Due to the paucity of crystal structures, homology modeling has become a widespread technique for the construction of GPCR models, which have been applied to the study of their structure-function relationships and to the identification of lead ligands through virtual screening. Rhodopsin has been for years the only available template. However, recent breakthroughs in GPCR crystallography have led to the solution of the structures of a few additional receptors. In light of these newly elucidated crystal structures, we have been able to produce a substantial amount of data to demonstrate that accurate models of GPCRs in complex with their ligands can be constructed through homology modeling followed by fully flexible molecular docking. These results have been confirmed by our success in the first blind assessment of GPCR modeling and docking, organized in coordination with the solution of the X-ray structure of the adenosine A(2A) receptor. Taken together, these data indicate that: a) the transmembrane helical bundle can be modeled with considerable accuracy; b) predicting the binding mode of a ligand, although doable, is challenging; c) modeling of the extracellular and intracellular loops is still problematic.
Homology Modeling of Class A G Protein-Coupled Receptors
Costanzi, Stefano
2012-01-01
G protein-coupled receptors (GPCRs) are a large superfamily of membrane bound signaling proteins that hold great pharmaceutical interest. Since experimentally elucidated structures are available only for a very limited number of receptors, homology modeling has become a widespread technique for the construction of GPCR models intended to study the structure-function relationships of the receptors and aid the discovery and development of ligands capable of modulating their activity. Through this chapter, various aspects involved in the constructions of homology models of the serpentine domain of the largest class of GPCRs, known as class A or rhodopsin family, are illustrated. In particular, the chapter provides suggestions, guidelines and critical thoughts on some of the most crucial aspect of GPCR modeling, including: collection of candidate templates and a structure-based alignment of their sequences; identification and alignment of the transmembrane helices of the query receptor to the corresponding domains of the candidate templates; selection of one or more templates receptor; election of homology or de novo modeling for the construction of specific extracellular and intracellular domains; construction of the three-dimensional models, with special consideration to extracellular regions, disulfide bridges, and interhelical cavity; validation of the models through controlled virtual screening experiments. PMID:22323225
NASA Astrophysics Data System (ADS)
Barthel, R.
2006-09-01
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.
Coupled hydrologic and hydraulic modeling of Upper Niger River Basin
NASA Astrophysics Data System (ADS)
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
Coupled Dynamic Modeling to Assess Human Impact on Watershed Hydrology
NASA Astrophysics Data System (ADS)
Mohammed, I. N.; Tsai, Y.; Turnbull, S.; Bomblies, A.; Zia, A.
2014-12-01
Humans are intrinsic to the hydrologic system, both as agents of change and as beneficiaries of ecosystem services. This connection has been underappreciated in hydrology. We present a modeling linkage framework of an agent-based land use change model with a physical-based watershed model. The coupled model framework presented constitutes part of an integrated assessment model that is being developed to study human-ecosystem interaction in Missisquoi Bay, spanning Vermont and Québec, which is experiencing high concentrations of nutrients from the Missisquoi River watershed. The integrated assessment approach proposed is comprised of linking two simulation models: the Interactive Land-Use Transition Agent-Based Model (ILUTABM) and a physically based process model, the Regional Hydro-Ecological Simulation System (RHESSys). The ILUTABM treats both landscape and landowners as agents and simulates annual land-use patterns resulting from landowners annual land-use decisions and Best Management Practices (BMPs) adaptations to landowners utilities, land productivity and perceived impacts of floods. The Missisquoi River at Swanton watershed RHESSys model (drainage area of 2,200 km2) driven by climate data was first calibrated to daily streamflows and water quality sensor data at the watershed outlet. Simulated land-use patterns were then processed to drive the calibrated RHESSys model to obtain streamflow nutrient loading realizations. Nutrients loading realizations are then examined and routed back to the ILUTAB model to obtain public polices needed to manage the Missisquoi watershed as well as the Lake Champlain in general. We infer that the applicability of this approach can be generalized to other similar watersheds. Index Terms: 0402: Agricultural systems; 1800: Hydrology; 1803: Anthropogenic effects; 1834 Human impacts; 6344: System operation and management; 6334: Regional Planning
Modelling couplings between reaction, fluid flow and deformation: Kinetics
NASA Astrophysics Data System (ADS)
Malvoisin, Benjamin; Podladchikov, Yury Y.; Connolly, James A. D.
2016-04-01
Mineral assemblages out of equilibrium are commonly found in metamorphic rocks testifying of the critical role of kinetics for metamorphic reactions. As experimentally determined reaction rates in fluid-saturated systems generally indicate complete reaction in less than several years, i.e. several orders of magnitude faster than field-based estimates, metamorphic reaction kinetics are generally thought to be controlled by transport rather than by processes at the mineral surface. However, some geological processes like earthquakes or slow-slip events have shorter characteristic timescales, and transport processes can be intimately related to mineral surface processes. Therefore, it is important to take into account the kinetics of mineral surface processes for modelling fluid/rock interactions. Here, a model coupling reaction, fluid flow and deformation was improved by introducing a delay in the achievement of equilibrium. The classical formalism for dissolution/precipitation reactions was used to consider the influence of the distance from equilibrium and of temperature on the reaction rate, and a dependence on porosity was introduced to model evolution of reacting surface area during reaction. The fitting of experimental data for three reactions typically occurring in metamorphic systems (serpentine dehydration, muscovite dehydration and calcite decarbonation) indicates a systematic faster kinetics close from equilibrium on the dehydration side than on the hydration side. This effect is amplified through the porosity term in the reaction rate since porosity is formed during dehydration. Numerical modelling indicates that this difference in reaction rate close from equilibrium plays a key role in microtextures formation. The developed model can be used in a wide variety of geological systems where couplings between reaction, deformation and fluid flow have to be considered.
Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal
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.
Modeling of price and profit in coupled-ring networks
NASA Astrophysics Data System (ADS)
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
NASA Astrophysics Data System (ADS)
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.
Modelling blast induced damage from a fully coupled explosive charge.
Onederra, Italo A; Furtney, Jason K; Sellers, Ewan; Iverson, Stephen
2013-02-01
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.
A fully coupled 2D model of equiaxed eutectic solidification
Charbon, Ch.; LeSar, R.
1995-12-31
We propose a model of equiaxed eutectic solidification that couples the macroscopic level of heat diffusion with the microscopic level of nucleation and growth of the eutectic grains. The heat equation with the source term corresponding to the latent heat release due to solidification is calculated numerically by means of an implicit finite difference method. In the time stepping scheme, the evolution of solid fraction is deduced from a stochastic model of nucleation and growth which uses the local temperature (interpolated from the FDM mesh) to determine the local grain density and the local growth rate. The solid-liquid interface of each grain is tracked by using a subdivision of each grain perimeter in a large number of sectors. The state of each sector (i.e. whether it is still in contact with the liquid or already captured by an other grain) and the increase of radius of each grain during one time step allows one to compute the increase of solid fraction. As for deterministic models, the results of the model are the evolution of temperature and of solid fraction at any point of the sample. Moreover the model provides a complete picture of the microstructure, thus not limiting the microstructural information to the average grain density but allowing one to compute any stereological value of interest. We apply the model to the solidification of gray cast iron.
A coupled vegetation/sediment transport model for dryland environments
NASA Astrophysics Data System (ADS)
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.
Coupling SWAT and ANN models for enhanced daily streamflow prediction
NASA Astrophysics Data System (ADS)
Noori, Navideh; Kalin, Latif
2016-02-01
To improve daily flow prediction in unmonitored watersheds a hybrid model was developed by combining a quasi-distributed watershed model and artificial neural network (ANN). Daily streamflow data from 29 nearby watersheds in and around the city of Atlanta, Southeastern United States, with leave-one-site-out jackknifing technique were used to build the flow predictive models during warm and cool seasons. Daily streamflow was first simulated with the Soil and Water Assessment Tool (SWAT) and then the SWAT simulated baseflow and stormflow were used as inputs to ANN. Out of the total 29 test watersheds, 62% and 83% of them had Nash-Sutcliffe values above 0.50 during the cool and warm seasons, respectively (considered good or better). As the percent forest cover or the size of test watershed increased, the performances of the models gradually decreased during both warm and cool seasons. This indicates that the developed models work better in urbanized watersheds. In addition, SWAT and SWAT Calibration Uncertainty Procedure (SWAT-CUP) program were run separately for each station to compare the flow prediction accuracy of the hybrid approach to SWAT. Only 31% of the sites during the calibration and 34% of validation runs had ENASH values ⩾0.50. This study showed that coupling ANN with semi-distributed models can lead to improved daily streamflow predictions in ungauged watersheds.
Wealth distribution of simple exchange models coupled with extremal dynamics
NASA Astrophysics Data System (ADS)
Bagatella-Flores, N.; Rodríguez-Achach, M.; Coronel-Brizio, H. F.; Hernández-Montoya, A. R.
2015-01-01
Punctuated Equilibrium (PE) states that after long periods of evolutionary quiescence, species evolution can take place in short time intervals, where sudden differentiation makes new species emerge and some species extinct. In this paper, we introduce and study the effect of punctuated equilibrium on two different asset exchange models: the yard sale model (YS, winner gets a random fraction of a poorer player's wealth) and the theft and fraud model (TF, winner gets a random fraction of the loser's wealth). The resulting wealth distribution is characterized using the Gini index. In order to do this, we consider PE as a perturbation with probability ρ of being applied. We compare the resulting values of the Gini index at different increasing values of ρ in both models. We found that in the case of the TF model, the Gini index reduces as the perturbation ρ increases, not showing dependence with the agents number. While for YS we observe a phase transition which happens around ρc = 0.79. For perturbations ρ <ρc the Gini index reaches the value of one as time increases (an extreme wealth condensation state), whereas for perturbations greater than or equal to ρc the Gini index becomes different to one, avoiding the system reaches this extreme state. We show that both simple exchange models coupled with PE dynamics give more realistic results. In particular for YS, we observe a power low decay of wealth distribution.
Reaching during virtual rotation: context specific compensations for expected coriolis forces
NASA Technical Reports Server (NTRS)
Cohn, J. V.; DiZio, P.; Lackner, J. R.
2000-01-01
Subjects who are in an enclosed chamber rotating at constant velocity feel physically stationary but make errors when pointing to targets. Reaching paths and endpoints are deviated in the direction of the transient inertial Coriolis forces generated by their arm movements. By contrast, reaching movements made during natural, voluntary torso rotation seem to be accurate, and subjects are unaware of the Coriolis forces generated by their movements. This pattern suggests that the motor plan for reaching movements uses a representation of body motion to prepare compensations for impending self-generated accelerative loads on the arm. If so, stationary subjects who are experiencing illusory self-rotation should make reaching errors when pointing to a target. These errors should be in the direction opposite the Coriolis accelerations their arm movements would generate if they were actually rotating. To determine whether such compensations exist, we had subjects in four experiments make visually open-loop reaches to targets while they were experiencing compelling illusory self-rotation and displacement induced by rotation of a complex, natural visual scene. The paths and endpoints of their initial reaching movements were significantly displaced leftward during counterclockwise illusory rotary displacement and rightward during clockwise illusory self-displacement. Subjects reached in a curvilinear path to the wrong place. These reaching errors were opposite in direction to the Coriolis forces that would have been generated by their arm movements during actual torso rotation. The magnitude of path curvature and endpoint errors increased as the speed of illusory self-rotation increased. In successive reaches, movement paths became straighter and endpoints more accurate despite the absence of visual error feedback or tactile feedback about target location. When subjects were again presented a stationary scene, their initial reaches were indistinguishable from pre
NASA Technical Reports Server (NTRS)
Lackner, J. R.; Dizio, P.
1998-01-01
We evaluated the combined effects on reaching movements of the transient, movement-dependent Coriolis forces and the static centrifugal forces generated in a rotating environment. Specifically, we assessed the effects of comparable Coriolis force perturbations in different static force backgrounds. Two groups of subjects made reaching movements toward a just-extinguished visual target before rotation began, during 10 rpm counterclockwise rotation, and after rotation ceased. One group was seated on the axis of rotation, the other 2.23 m away. The resultant of gravity and centrifugal force on the hand was 1.0 g for the on-center group during 10 rpm rotation, and 1.031 g for the off-center group because of the 0.25 g centrifugal force present. For both groups, rightward Coriolis forces, approximately 0.2 g peak, were generated during voluntary arm movements. The endpoints and paths of the initial per-rotation movements were deviated rightward for both groups by comparable amounts. Within 10 subsequent reaches, the on-center group regained baseline accuracy and straight-line paths; however, even after 40 movements the off-center group had not resumed baseline endpoint accuracy. Mirror-image aftereffects occurred when rotation stopped. These findings demonstrate that manual control is disrupted by transient Coriolis force perturbations and that adaptation can occur even in the absence of visual feedback. An increase, even a small one, in background force level above normal gravity does not affect the size of the reaching errors induced by Coriolis forces nor does it affect the rate of reacquiring straight reaching paths; however, it does hinder restoration of reaching accuracy.
Reaching during virtual rotation: context specific compensations for expected coriolis forces.
Cohn, J V; DiZio, P; Lackner, J R
2000-06-01
Subjects who are in an enclosed chamber rotating at constant velocity feel physically stationary but make errors when pointing to targets. Reaching paths and endpoints are deviated in the direction of the transient inertial Coriolis forces generated by their arm movements. By contrast, reaching movements made during natural, voluntary torso rotation seem to be accurate, and subjects are unaware of the Coriolis forces generated by their movements. This pattern suggests that the motor plan for reaching movements uses a representation of body motion to prepare compensations for impending self-generated accelerative loads on the arm. If so, stationary subjects who are experiencing illusory self-rotation should make reaching errors when pointing to a target. These errors should be in the direction opposite the Coriolis accelerations their arm movements would generate if they were actually rotating. To determine whether such compensations exist, we had subjects in four experiments make visually open-loop reaches to targets while they were experiencing compelling illusory self-rotation and displacement induced by rotation of a complex, natural visual scene. The paths and endpoints of their initial reaching movements were significantly displaced leftward during counterclockwise illusory rotary displacement and rightward during clockwise illusory self-displacement. Subjects reached in a curvilinear path to the wrong place. These reaching errors were opposite in direction to the Coriolis forces that would have been generated by their arm movements during actual torso rotation. The magnitude of path curvature and endpoint errors increased as the speed of illusory self-rotation increased. In successive reaches, movement paths became straighter and endpoints more accurate despite the absence of visual error feedback or tactile feedback about target location. When subjects were again presented a stationary scene, their initial reaches were indistinguishable from pre
Lackner, J R; Dizio, P
1998-08-01
We evaluated the combined effects on reaching movements of the transient, movement-dependent Coriolis forces and the static centrifugal forces generated in a rotating environment. Specifically, we assessed the effects of comparable Coriolis force perturbations in different static force backgrounds. Two groups of subjects made reaching movements toward a just-extinguished visual target before rotation began, during 10 rpm counterclockwise rotation, and after rotation ceased. One group was seated on the axis of rotation, the other 2.23 m away. The resultant of gravity and centrifugal force on the hand was 1.0 g for the on-center group during 10 rpm rotation, and 1.031 g for the off-center group because of the 0.25 g centrifugal force present. For both groups, rightward Coriolis forces, approximately 0.2 g peak, were generated during voluntary arm movements. The endpoints and paths of the initial per-rotation movements were deviated rightward for both groups by comparable amounts. Within 10 subsequent reaches, the on-center group regained baseline accuracy and straight-line paths; however, even after 40 movements the off-center group had not resumed baseline endpoint accuracy. Mirror-image aftereffects occurred when rotation stopped. These findings demonstrate that manual control is disrupted by transient Coriolis force perturbations and that adaptation can occur even in the absence of visual feedback. An increase, even a small one, in background force level above normal gravity does not affect the size of the reaching errors induced by Coriolis forces nor does it affect the rate of reacquiring straight reaching paths; however, it does hinder restoration of reaching accuracy.
NASA Technical Reports Server (NTRS)
Lackner, J. R.; Dizio, P.
1998-01-01
We evaluated the combined effects on reaching movements of the transient, movement-dependent Coriolis forces and the static centrifugal forces generated in a rotating environment. Specifically, we assessed the effects of comparable Coriolis force perturbations in different static force backgrounds. Two groups of subjects made reaching movements toward a just-extinguished visual target before rotation began, during 10 rpm counterclockwise rotation, and after rotation ceased. One group was seated on the axis of rotation, the other 2.23 m away. The resultant of gravity and centrifugal force on the hand was 1.0 g for the on-center group during 10 rpm rotation, and 1.031 g for the off-center group because of the 0.25 g centrifugal force present. For both groups, rightward Coriolis forces, approximately 0.2 g peak, were generated during voluntary arm movements. The endpoints and paths of the initial per-rotation movements were deviated rightward for both groups by comparable amounts. Within 10 subsequent reaches, the on-center group regained baseline accuracy and straight-line paths; however, even after 40 movements the off-center group had not resumed baseline endpoint accuracy. Mirror-image aftereffects occurred when rotation stopped. These findings demonstrate that manual control is disrupted by transient Coriolis force perturbations and that adaptation can occur even in the absence of visual feedback. An increase, even a small one, in background force level above normal gravity does not affect the size of the reaching errors induced by Coriolis forces nor does it affect the rate of reacquiring straight reaching paths; however, it does hinder restoration of reaching accuracy.
Reaching during virtual rotation: context specific compensations for expected coriolis forces
NASA Technical Reports Server (NTRS)
Cohn, J. V.; DiZio, P.; Lackner, J. R.
2000-01-01
Subjects who are in an enclosed chamber rotating at constant velocity feel physically stationary but make errors when pointing to targets. Reaching paths and endpoints are deviated in the direction of the transient inertial Coriolis forces generated by their arm movements. By contrast, reaching movements made during natural, voluntary torso rotation seem to be accurate, and subjects are unaware of the Coriolis forces generated by their movements. This pattern suggests that the motor plan for reaching movements uses a representation of body motion to prepare compensations for impending self-generated accelerative loads on the arm. If so, stationary subjects who are experiencing illusory self-rotation should make reaching errors when pointing to a target. These errors should be in the direction opposite the Coriolis accelerations their arm movements would generate if they were actually rotating. To determine whether such compensations exist, we had subjects in four experiments make visually open-loop reaches to targets while they were experiencing compelling illusory self-rotation and displacement induced by rotation of a complex, natural visual scene. The paths and endpoints of their initial reaching movements were significantly displaced leftward during counterclockwise illusory rotary displacement and rightward during clockwise illusory self-displacement. Subjects reached in a curvilinear path to the wrong place. These reaching errors were opposite in direction to the Coriolis forces that would have been generated by their arm movements during actual torso rotation. The magnitude of path curvature and endpoint errors increased as the speed of illusory self-rotation increased. In successive reaches, movement paths became straighter and endpoints more accurate despite the absence of visual error feedback or tactile feedback about target location. When subjects were again presented a stationary scene, their initial reaches were indistinguishable from pre
Perception--action coupling model for human locomotor pointing.
de Rugy, A; Taga, G; Montagne, G; Buekers, M J; Laurent, M
2002-08-01
How do humans achieve the precise positioning of the feet during walking, for example, to reach the first step of a stairway? We addressed this question at the visuomotor integration level. Based on the optical specification of the required adaptation, a dynamical system model of the visuomotor control of human locomotor pointing was devised for the positioning of a foot on a visible target on the floor during walking. Visuomotor integration consists of directly linking optical information to a motor command that specifically modulates step length in accordance with the ongoing dynamics of locomotor pattern generation. The adaptation of locomotion emerges from a perception-action coupling type of control based on temporal information rather than on feedforward planning of movements. The proposed model reproduces experimental results obtained for human locomotor pointing.
Models of radiofrequency coupling for negative ion sources
Cavenago, M.; Petrenko, S.
2012-02-15
Radiofrequency heating for ICP (inductively coupled plasma) ion sources depends on the source operating pressure, the presence or absence of a Faraday shield, the driver coil geometry, the frequency used, and the magnetic field configuration: in negative ion source a magnetic filter seems necessary for H{sup -} survival. The result of single particle simulations showing the possibility of electron acceleration in the preglow regime and for reasonable driver chamber radius (15 cm) is reported, also as a function of the static external magnetic field. An effective plasma conductivity, depending not only from electron density, temperature, and rf field but also on static magnetic field is here presented and compared to previous models. Use of this conductivity and of multiphysics tools for a plasma transport and heating model is shown and discussed for a small source.
Representing Icebergs In A Fully Coupled Climate Model
NASA Astrophysics Data System (ADS)
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
Minimal coupling model of the biaxial nematic phase
NASA Astrophysics Data System (ADS)
Longa, Lech; Grzybowski, Piotr; Romano, Silvano; Virga, Epifanio
2005-05-01
A minimal coupling model exhibiting isotropic, uniaxial, and biaxial nematic phases is analyzed in detail and its relation to existing models known in the literature is clarified. Its intrinsic symmetry properties are exploited to restrict the relevant ranges of coupling constants. Further on, properties of the model are thoroughly investigated by means of bifurcation theory as proposed by Kayser and Raveché [Phys. Rev. A 17, 2067 (1978)] and Mulder [Phys. Rev. A 39, 360 (1989)]. As a first step toward this goal, the bifurcation theory is applied to a general formulation of density functional theory in terms of direct correlation functions. On a general formal level, the theory is then analyzed to show that the bifurcation points from the reference, high-symmetry equilibrium phase to a low-symmetry structure depend only on the properties of the one-particle distribution function and the direct pair correlation function of the reference phase. The character of the bifurcation (whether spinodal, critical, tricritical, isolated Landau point, etc.) depends, in addition, on a few higher-order direct correlation functions. Explicit analytical results are derived for the case when only the leading L=2 terms of the potential (mean-field analysis) or of the direct pair correlation function expansion in the symmetry-adapted basis are retained. Formulas are compared with the numerical calculations for the mean-field, momentum L=2 potential model, in which case they are exact. In particular, bifurcations from the isotropic and uniaxial nematic to the biaxial nematic phases are discussed. The possibility of the recently reported nematic uniaxial-nematic biaxial tricritical point [A. M. Sonnet, E. G. Virga, and G. E. Durand, Phys. Rev. E 67, 061701 (2003)] is analyzed as well.
Coupled Modeling of Fault Poromechanics During Geologic CO2 Storage
NASA Astrophysics Data System (ADS)
Jha, B.; Hager, B. H.; Juanes, R.
2012-12-01
Perhaps the most pressing current debate surrounding carbon capture and storage (CCS) revolves around the pressure limitations on geologic storage [Szulczewski et al., 2012]. Overpressures due to CO2 injection could fracture the caprock [Birkholzer and Zhou, 2009], trigger earthquakes [Cappa and Rutqvist, 2011], and potentially compromise the caprock by activating faults [Zoback and Gorelick, 2012]. While an alarmist view of these issues [Zoback and Gorelick, 2012] appears unwarranted, it seems clear that addressing the coupled processes of CO2 injection and fault poromechanics constitutes a pressing challenge for CCS. More generally, the fundamental link between earthquakes and groundwater flow is a first-order geoscience problem. Despite the interest that this issue has received in recent times, many aspects remain poorly understood, from the physics of the problem to the ability to perform credible fully-coupled simulations. Here, we advance our current simulation technology for forecasting fault slip and fault activation from fluid injection and withdrawal at depth. We present the development and application of a coupled multiphase-flow and reservoir-geomechanics simulator able to model the poromechanics of faults. We use a recently-discovered operator split, the fixed-stress split [Kim et al., 2011], to obtain an unconditionally-stable sequential iterative scheme for the simulation of multiphase flow and geomechanics. The geomechanics code PyLith [Aagaard et al., 2011] permits simulating faults as surfaces of discontinuity. We use the rigorous nonlinear formulation of coupled geomechanics, in which the variation in the fluid mass of each phase is tracked [Coussy, 1995]. Our approach allows us to model strong capillarity and compressibility effects, which can be important in the context of CO2 injection. We present results from several synthetic case studies to highlight the main features of our simulator, and to perform a preliminary risk assessment of leakage
A Coupled Surface/Subsurface Model for Hydrological Drought Investigations
NASA Astrophysics Data System (ADS)
Musuuza, J. L.; Kumar, R.; Samaniego, L. E.; Fischer, T.; Kolditz, O.; Attinger, S.
2013-12-01
Hydrological droughts occur when storage in the ground and surface-water bodies falls below statistical average. Due to the inclusion of regional groundwater, hydrological droughts evolve relatively slowly. The atmospheric and surface components of the hydrological cycle have been widely studied, are well understood, and their prognoses are fairly accurate. In large-scale land surface models on the other hand, subsurface (groundwater) flow processes are usually assumed unidirectional and limited to the vertically-downward percolation and the horizontal runoffs. The vertical feedback from groundwater to the unsaturated zone as well as the groundwater recharge from surface waters are usually misrepresented, resulting in poor model performance during low-flow periods. The feedback is important during meteorological droughts because it replenishes soil moisture from ground- and surface water, thereby delaying the onset of agricultural droughts. If sustained for long periods however, the depletion can significantly reduce surface and subsurface storage and lead to severe hydrological droughts. We hypothesise that an explicit incorporation of the groundwater component into an existing land surface model would lead to better representation of low flows, which is critical for drought analyses. It would also improve the model performance during low-flow periods. For this purpose, we coupled the process-based mHM surface model (Samaniego et al. 2010) with MODFLOW (Harbaugh 2005) to analyse droughts in the Unstrut catchment, one of the tributaries of the Elbe. The catchment is located in one of the most drought-prone areas of Germany. We present results for stand-alone and coupled mHM simulations for the period 1970-2000. References Arlen W. Harbaugh. MODFLOW-2005, The U.S. Geological Survey Modular Ground-water Model-the Ground-water Flow Process, chapter Modelling techniques, sec. A. Ground water, pages 1:1-9:62. USGS, 2005. Luis Samaniego, Rohini Kumar, and Sabine Attinger
Coupled thermal and geophysical modelling for monitoring of permafrost
NASA Astrophysics Data System (ADS)
Rings, Jörg; Scherler, Martin; Hauck, Christian
2010-05-01
Geophysical methods, and especially the Electrical Resistivity Tomography (ERT) method, are being recognised as standard tools for the detection and monitoring of permafrost. Recent advances in automated data acquisition and processing have made their application worthwhile for continuous monitoring systems even in harsh and heterogeneous terrain. ERT yields 2- and 3-dimensional data of the subsurface and is sensitive to the unfrozen water and ice content, which is complementary to the 1-dimensional temperature measurements conducted in boreholes. For future autonomous and widespread monitoring systems for permafrost, a purely geophysical approach is envisaged, because the low costs and minimal disturbance of the system to be monitored is one of the major advantages of geophysics as opposed to boreholes. However, the link between the indirectly measured geophysical property (e.g. electrical resistivity in case of ERT) of the subsurface and temperature is often non-trivial and cannot be determined without ground truth data from boreholes or extensive laboratory calibration. In this contribution, we introduce a Bayesian filtering approach of coupled geophysical and thermal modelling to predict subsurface temperatures based on ERT monitoring data without the need for borehole or laboratory data. We use sequential Bayesian filtering or particle filtering, which has the advantage of continuously providing probability distributions of state (temperature) and parameters (e.g. the link between resistivity and temperature) whenever measurements become available. A particle filter approximates these distributions by a set of discrete, weighted particles. For each particle, initial state and parameter are drawn from prior distributions and thermal conduction is modelled independently. The modelled change in temperature is transferred to change in resistivity by a linear relation, and an ERT forward model is used to simulate the system response. Then, the particles are
Coupled thermo-hydro-chemical models of swelling bentonites
NASA Astrophysics Data System (ADS)
Samper, Javier; Mon, Alba; Zheng, Liange; Montenegro, Luis; Naves, Acacia; Pisani, Bruno
2014-05-01
The disposal of radioactive waste in deep geological repositories is based on the multibarrier concept of retention of the waste by a combination of engineered and geological barriers. The engineered barrier system (EBS) includes the solid conditioned waste-form, the waste container, the buffer made of materials such as clay, grout or crushed rock that separate the waste package from the host rock and the tunnel linings and supports. The geological barrier supports the engineered system and provides stability over the long term during which time radioactive decay reduces the levels of radioactivity. The strong interplays among thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the hydration, thermal and solute transport stages of the engineered barrier system (EBS) of a radioactive waste repository call for coupled THMC models for the metallic overpack, the unsaturated compacted bentonite and the concrete liner. Conceptual and numerical coupled THMC models of the EBS have been developed, which have been implemented in INVERSE-FADES-CORE. Chemical reactions are coupled to the hydrodynamic processes through chemical osmosis (C-H coupling) while bentonite swelling affects solute transport via changes in bentonite porosity changes (M-H coupling). Here we present THMC models of heating and hydration laboratory experiments performed by CIEMAT (Madrid, Spain) on compacted FEBEX bentonite and numerical models for the long-term evolution of the EBS for 1 Ma. The changes in porosity caused by swelling are more important than those produced by the chemical reactions during the early evolution of the EBS (t < 100 years). For longer times, however, the changes in porosity induced by the dissolution/precipitation reactions are more relevant due to: 1) The effect of iron mineral phases (corrosion products) released by the corrosion of the carbon steel canister; and 2) The hyper alkaline plume produced by the concrete liner. Numerical results show that
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.
Thermo-mechanical phase-shift determination in Coriolis mass-flowmeters with added masses
NASA Astrophysics Data System (ADS)
Ghayesh, Mergen H.; Amabili, Marco; Païdoussis, Michael P.
2012-10-01
The aim of this paper is to develop an approximate analytical solution for phase-shift (and thus mass flow) prediction along the length of the measuring tube of a Coriolis mass-flowmeter. A single, straight measuring tube is considered; added masses at the sensor and excitation locations are included in the model, and thus in the equation of motion. The measuring tube is excited harmonically by an electromagnetic driver. Taking into account thermal effects, the equation of motion is derived through use of the extended Hamilton's principle and constitutive relations. The equation of motion is discretized into a set of ordinary differential equations via Galerkin's technique. The method of multiple timescales is applied to the set of resultant equations, and the equations of order one and epsilon are obtained analytically for the system at primary resonance. The solution of the equation of motion is obtained by satisfying the solvability condition (making the solution of order epsilon free of secular terms). The flow-related phase-shift in the driver-induced tube vibration is measured at two symmetrically located points on either side of the mid-length of the tube. The analytical results for the phase-shift are compared to those obtained numerically. The effect of system parameters on the measured phase-shift is discussed. It is shown that the measured phase-shift depends on the mass flow rate, of course, but it is also affected by the magnitude of the added sensor mass and location, and the temperature change; nevertheless, the factors investigated do not induce a zero phase-shift.
Indian Ocean sea surface salinity variations in a coupled model
NASA Astrophysics Data System (ADS)
Vinayachandran, P. N.; Nanjundiah, Ravi S.
2009-08-01
The variability of the sea surface salinity (SSS) in the Indian Ocean is studied using a 100-year control simulation of the Community Climate System Model (CCSM 2.0). The monsoon-driven seasonal SSS pattern in the Indian Ocean, marked by low salinity in the east and high salinity in the west, is captured by the model. The model overestimates runoff into the Bay of Bengal due to higher rainfall over the Himalayan-Tibetan regions which drain into the Bay of Bengal through Ganga-Brahmaputra rivers. The outflow of low-salinity water from the Bay of Bengal is too strong in the model. Consequently, the model Indian Ocean SSS is about 1 less than that seen in the climatology. The seasonal Indian Ocean salt balance obtained from the model is consistent with the analysis from climatological data sets. During summer, the large freshwater input into the Bay of Bengal and its redistribution decide the spatial pattern of salinity tendency. During winter, horizontal advection is the dominant contributor to the tendency term. The interannual variability of the SSS in the Indian Ocean is about five times larger than that in coupled model simulations of the North Atlantic Ocean. Regions of large interannual standard deviations are located near river mouths in the Bay of Bengal and in the eastern equatorial Indian Ocean. Both freshwater input into the ocean and advection of this anomalous flux are responsible for the generation of these anomalies. The model simulates 20 significant Indian Ocean Dipole (IOD) events and during IOD years large salinity anomalies appear in the equatorial Indian Ocean. The anomalies exist as two zonal bands: negative salinity anomalies to the north of the equator and positive to the south. The SSS anomalies for the years in which IOD is not present and for ENSO years are much weaker than during IOD years. Significant interannual SSS anomalies appear in the Indian Ocean only during IOD years.
River-Ocean Interactions: A Coupled Morphodynamic Delta Model
NASA Astrophysics Data System (ADS)
Ratliff, K. M.; Hutton, E. W. H.; Murray, A. B.
2015-12-01
Society has become increasingly reliant on deltas for agriculture, resource extraction, transportation and trade, yet these landforms and their inhabitants have become increasingly vulnerable to submergence and natural disasters (e.g., flooding, storm surges). Although we know that many 'natural' processes influence large-scale delta morphology, we do not yet know the relative importance of anthropogenic influences (e.g., climate and land-use change) in shaping modern deltas. In particular, the processes and feedbacks that shape delta morphology over large space and timescales (i.e. timescales of multiple river avulsions and the evolution of multiple delta lobes) are not well understood. To explore the long-term combined effects of sea-level rise, subsidence and anthropogenic manipulations, we have developed a new morphodynamic delta model that links fluvial, floodplain, and deltaic dynamics over large space and timescales. Using the framework and tools of the Community Surface Dynamics Modeling System, we couple a new river and floodplain module to the Coastline Evolution Model (CEM, Ashton and Murray, 2001). In the fluvial module, cell width is assumed to be larger than the channel belt width (including natural levees that are maintained at a bankfull channel-depth above the riverbed elevation). The river course is determined using a steepest-descent methodology, and erosion and deposition along the course is modeled as a linear diffusive process. An avulsion occurs when the riverbed becomes super-elevated above the surrounding floodplain, and the new steepest-descent path to sea level is shorter than the previous course. Floodplain deposition is modeled by blanket (uniform) deposition and crevasse splay deposition (after a 'failed' avulsion; if the riverbed is super-elevated, but the new steepest path to sea level is longer than the prior path). Preliminary results indicate that anthropogenic manipulations of the river (e.g., levees) can propagate hundreds of
Early Eocene's climate and ocean circulation from coupled model simulations
NASA Astrophysics Data System (ADS)
Weber, Tobias; Thomas, Maik
2014-05-01
While proxy data provide a snapshot of climate conditions at a specific location, coupled atmosphere-ocean models are able to expand this knowledge over the globe. Therefore, they are indispensable tools for understanding past climate conditions. We model the dynamical state of atmosphere and ocean during the Early Eocene and pre-industrial times, using the coupled atmosphere-ocean model ECHAM5/MPIOM with realistic reconstructions of vegetation and CO2. The resulting simulated climate variables are compared to terrestrial and oceanic proxies. The Early Eocene climate is in the global mean warmer (~13°C) and wetter (~1 mm/d) than in pre-industrial times. Especially temperatures in the Southern Ocean, the Greenland Sea and Arctic Ocean raise by up to 25K, being in accordance with surface temperature estimates from terrestrial and marine proxy data. The oceans are hereby rendered ice-free, leading to a decrease of polar albedo and thereby facilitating polar warming. This leads to a by 5K diminished equator-to-pole temperature gradient. Warmer temperatures as well as changed bathymetry have an effect on ocean dynamics in the Early Eocene. Although deep-water formation can be found in the Greenland Sea, Weddell Sea, and Tethys Sea, it is weaker than in the pre-industrial run and the resulting circulation is shallower. This is not only visible in water transport through sea gates but also in the Atlantic Meridional Overturning Circulation (AMOC), adopting its maximum at 700m depths in the Early Eocene, while maximum transport is reached in the pre-industrial control run at 1200m. Albeit a shallow and weak thermohaline circulation, a global ocean conveyor belt is being triggered, causing a transport from the areas of subduction through the Atlantic and Southern Oceans into the Indian and Pacific Oceans.
Coupled mode parametric resonance in a vibrating screen model
NASA Astrophysics Data System (ADS)
Slepyan, Leonid I.; Slepyan, Victor I.
2014-02-01
We consider a simple dynamic model of the vibrating screen operating in the parametric resonance (PR) mode. This model was used in the course of designing and setting of such a screen in LPMC. The PR-based screen compares favorably with conventional types of such machines, where the transverse oscillations are excited directly. It is characterized by larger values of the amplitude and by insensitivity to damping in a rather wide range. The model represents an initially strained system of two equal masses connected by a linearly elastic string. Self-equilibrated, longitudinal, harmonic forces act on the masses. Under certain conditions this results in transverse, finite-amplitude oscillations of the string. The problem is reduced to a system of two ordinary differential equations coupled by the geometric nonlinearity. Damping in both the transverse and longitudinal oscillations is taken into account. Free and forced oscillations of this mass-string system are examined analytically and numerically. The energy exchange between the longitudinal and transverse modes of free oscillations is demonstrated. An exact analytical solution is found for the forced oscillations, where the coupling plays the role of a stabilizer. In a more general case, the harmonic analysis is used with neglect of the higher harmonics. Explicit expressions for all parameters of the steady nonlinear oscillations are determined. The domains are found where the analytically obtained steady oscillation regimes are stable. Over the frequency ranges, where the steady oscillations exist, a perfect correspondence is found between the amplitudes obtained analytically and numerically. Illustrations based on the analytical and numerical simulations are presented.
Model spin-orbit coupling Hamiltonians for graphene systems
NASA Astrophysics Data System (ADS)
Kochan, Denis; Irmer, Susanne; Fabian, Jaroslav
2017-04-01
We present a detailed theoretical study of effective spin-orbit coupling (SOC) Hamiltonians for graphene-based systems, covering global effects such as proximity to substrates and local SOC effects resulting, for example, from dilute adsorbate functionalization. Our approach combines group theory and tight-binding descriptions. We consider structures with global point group symmetries D6 h, D3 d, D3 h, C6 v, and C3 v that represent, for example, pristine graphene, graphene miniripple, planar boron nitride, graphene on a substrate, and free standing graphone, respectively. The presence of certain spin-orbit coupling parameters is correlated with the absence of the specific point group symmetries. Especially in the case of C6 v—graphene on a substrate, or transverse electric field—we point out the presence of a third SOC parameter, besides the conventional intrinsic and Rashba contributions, thus far neglected in literature. For all global structures we provide effective SOC Hamiltonians both in the local atomic and Bloch forms. Dilute adsorbate coverage results in the local point group symmetries C6 v, C3 v, and C2 v, which represent the stable adsorption at hollow, top and bridge positions, respectively. For each configuration we provide effective SOC Hamiltonians in the atomic orbital basis that respect local symmetries. In addition to giving specific analytic expressions for model SOC Hamiltonians, we also present general (no-go) arguments about the absence of certain SOC terms.
Affine group formulation of the Standard Model coupled to gravity
Chou, Ching-Yi; Ita, Eyo; Soo, Chopin
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
Minimally coupled scalar field cosmology in anisotropic cosmological model
NASA Astrophysics Data System (ADS)
Singh, C. P.; Srivastava, Milan
2017-02-01
We study a spatially homogeneous and anisotropic cosmological model in the Einstein gravitational theory with a minimally coupled scalar field. We consider a non-interacting combination of scalar field and perfect fluid as the source of matter components which are separately conserved. The dynamics of cosmic scalar fields with a zero rest mass and an exponential potential are studied, respectively. We find that both assumptions of potential along with the average scale factor as an exponential function of scalar field lead to the logarithmic form of scalar field in each case which further gives power-law form of the average scale factor. Using these forms of the average scale factor, exact solutions of the field equations are obtained to the metric functions which represent a power-law and a hybrid expansion, respectively. We find that the zero-rest-mass model expands with decelerated rate and behaves like a stiff matter. In the case of exponential potential function, the model decelerates, accelerates or shows the transition depending on the parameters. The isotropization is observed at late-time evolution of the Universe in the exponential potential model.
A coupled regional climate-biosphere model for climate studies
Bossert, J.; Winterkamp, J.; Barnes, F.; Roads, J.
1996-04-01
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop and test a regional climate modeling system that couples a limited-area atmospheric code to a biosphere scheme that properly represents surface processes. The development phase has included investigations of the impact of variations in surface forcing parameters, meteorological input data resolution, and model grid resolution. The testing phase has included a multi-year simulation of the summer climate over the Southwest United States at higher resolution than previous studies. Averaged results from a nine summer month simulation demonstrate the capability of the regional climate model to produce a representative climatology of the Southwest. The results also show the importance of strong summertime thermal forcing of the surface in defining this climatology. These simulations allow us to observe the climate at much higher temporal and spatial resolutions than existing observational networks. The model also allows us to see the full three-dimensional state of the climate and thereby deduce the dominant physical processes at any particular time.
Coupled model of physical and biological processes affecting maize pollination
NASA Astrophysics Data System (ADS)
Arritt, R.; Westgate, M.; Riese, J.; Falk, M.; Takle, E.
2003-04-01
Controversy over the use of genetically modified (GM) crops has led to increased interest in evaluating and controlling the potential for inadvertent outcrossing in open-pollinated crops such as maize. In response to this problem we have developed a Lagrangian model of pollen dispersion as a component of a coupled end-to-end (anther to ear) physical-biological model of maize pollination. The Lagrangian method is adopted because of its generality and flexibility: first, the method readily accommodates flow fields of arbitrary complexity; second, each element of the material being transported can be identified by its source, time of release, or other properties of interest. The latter allows pollen viability to be estimated as a function of such factors as travel time, temperature, and relative humidity, so that the physical effects of airflow and turbulence on pollen dispersion can be considered together with the biological aspects of pollen release and viability. Predicted dispersion of pollen compares well both to observations and to results from a simpler Gaussian plume model. Ability of the Lagrangian model to handle complex air flows is demonstrated by application to pollen dispersion in the vicinity of an agricultural shelter belt. We also show results indicating that pollen viability can be quantified by an "aging function" that accounts for temperature, humidity, and time of exposure.
Coupled Thermal-Chemical-Mechanical Modeling of Validation Cookoff Experiments
ERIKSON,WILLIAM W.; SCHMITT,ROBERT G.; ATWOOD,A.I.; CURRAN,P.D.
2000-11-27
The cookoff of energetic materials involves the combined effects of several physical and chemical processes. These processes include heat transfer, chemical decomposition, and mechanical response. The interaction and coupling between these processes influence both the time-to-event and the violence of reaction. The prediction of the behavior of explosives during cookoff, particularly with respect to reaction violence, is a challenging task. To this end, a joint DoD/DOE program has been initiated to develop models for cookoff, and to perform experiments to validate those models. In this paper, a series of cookoff analyses are presented and compared with data from a number of experiments for the aluminized, RDX-based, Navy explosive PBXN-109. The traditional thermal-chemical analysis is used to calculate time-to-event and characterize the heat transfer and boundary conditions. A reaction mechanism based on Tarver and McGuire's work on RDX{sup 2} was adjusted to match the spherical one-dimensional time-to-explosion data. The predicted time-to-event using this reaction mechanism compares favorably with the validation tests. Coupled thermal-chemical-mechanical analysis is used to calculate the mechanical response of the confinement and the energetic material state prior to ignition. The predicted state of the material includes the temperature, stress-field, porosity, and extent of reaction. There is little experimental data for comparison to these calculations. The hoop strain in the confining steel tube gives an estimation of the radial stress in the explosive. The inferred pressure from the measured hoop strain and calculated radial stress agree qualitatively. However, validation of the mechanical response model and the chemical reaction mechanism requires more data. A post-ignition burn dynamics model was applied to calculate the confinement dynamics. The burn dynamics calculations suffer from a lack of characterization of the confinement for the flaw
A coupled oscillator model of shelf and ocean tides
NASA Astrophysics Data System (ADS)
Arbic, Brian K.; Garrett, Chris
2010-04-01
The resonances of tides in the coupled open ocean and shelf are modeled by a mechanical analogue consisting of a damped driven larger mass and spring (the open-ocean) connected to a damped smaller mass and spring (the shelf). When both masses are near resonance, the addition of even a very small mass can significantly affect the oscillations of the larger mass. The influence of the shelf is largest if the shelf is resonant with weak friction. In particular, an increase of friction on a near-resonant shelf can, perhaps surprisingly, lead to an increase in ocean tides. On the other hand, a shelf with large friction has little effect on ocean tides. Comparison of the model predictions with results from numerical models of tides during the ice ages, when lower sea levels led to a much reduced areal extent of shelves, suggests that the predicted larger tidal dissipation then is related to the ocean basins being close to resonance. New numerical simulations with a forward global tide model are used to test expectations from the mechanical analogue. Setting friction to unrealistically large values in Hudson Strait yields larger North Atlantic M2 amplitudes, very similar to those seen in a simulation with the Hudson Strait blocked off. Thus, as anticipated, a shelf with very large friction is nearly equivalent in its effect on the open ocean to the removal of the shelf altogether. Setting friction in shallow waters throughout the globe to unrealistically large values yields even larger open ocean tidal amplitudes, similar to those found in simulations of ice-age tides. It thus appears that larger modeled tides during the ice ages can be a consequence of enhanced friction in shallower water on the shelf in glacial times as well as a reduced shelf area then. Single oscillator and coupled oscillator models for global tides show that the maximum extractable power for human use is a fraction of the present dissipation rate, which is itself a fraction of global human power
Acoustically-coupled flow-induced vibration of a computational vocal fold model.
Daily, David Jesse; Thomson, Scott L
2013-01-15
The flow-induced vibration of synthetic vocal fold models has been previously observed to be acoustically-coupled with upstream flow supply tubes. This phenomenon was investigated using a finite element model that included flow-structure-acoustic interactions. The length of the upstream duct was varied to explore the coupling between model vibration and subglottal acoustics. Incompressible and slightly compressible flow models were tested. The slightly compressible model exhibited acoustic coupling between fluid and solid domains in a manner consistent with experimental observations, whereas the incompressible model did not, showing the slightly compressible approach to be suitable for simulating acoustically-coupled vocal fold model flow-induced vibration.
Acoustically-coupled flow-induced vibration of a computational vocal fold model
Daily, David Jesse; Thomson, Scott L.
2012-01-01
The flow-induced vibration of synthetic vocal fold models has been previously observed to be acoustically-coupled with upstream flow supply tubes. This phenomenon was investigated using a finite element model that included flow–structure–acoustic interactions. The length of the upstream duct was varied to explore the coupling between model vibration and subglottal acoustics. Incompressible and slightly compressible flow models were tested. The slightly compressible model exhibited acoustic coupling between fluid and solid domains in a manner consistent with experimental observations, whereas the incompressible model did not, showing the slightly compressible approach to be suitable for simulating acoustically-coupled vocal fold model flow-induced vibration. PMID:23585700
Billon, Alexis; Foy, Cédric; Picaut, Judicaël; Valeau, Vincent; Sakout, Anas
2008-06-01
In this paper, a modification of the diffusion model for room acoustics is proposed to account for sound transmission between two rooms, a source room and an adjacent room, which are coupled through a partition wall. A system of two diffusion equations, one for each room, together with a set of two boundary conditions, one for the partition wall and one for the other walls of a room, is obtained and numerically solved. The modified diffusion model is validated by numerical comparisons with the statistical theory for several coupled-room configurations by varying the coupling area surface, the absorption coefficient of each room, and the volume of the adjacent room. An experimental comparison is also carried out for two coupled classrooms. The modified diffusion model results agree very well with both the statistical theory and the experimental data. The diffusion model can then be used as an alternative to the statistical theory, especially when the statistical theory is not applicable, that is, when the reverberant sound field is not diffuse. Moreover, the diffusion model allows the prediction of the spatial distribution of sound energy within each coupled room, while the statistical theory gives only one sound level for each room.
Properties of Coupled Oscillator Model for Bidirectional Associative Memory
NASA Astrophysics Data System (ADS)
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.
Understanding Core-Mantle Coupling Through Dynamo Models
NASA Astrophysics Data System (ADS)
Sreenivasan, B.
2007-12-01
Core-mantle interaction in the Earth is studied using convection-driven dynamo models. We begin by considering an idealized regime that supports locking of the fluid motion and magnetic field to external inhomogeneities. In perfect locking, the azimuthal velocity in the fluid core has the profile of a thermal wind imposed by the boundary. In strongly convective dynamos, the competition between buoyancy-driven and boundary-driven thermal winds determines the extent of fluid-boundary coupling. We go on to show that dynamos with weakly convecting outer layers support locking, whereas strongly convecting outer regions swamp any influence of the lateral variations at the boundary. Finally, we investigate the tomographic boundary condition to see how its individual harmonic components may affect the morphology of the geomagnetic field.
Finite Hypernuclei in the Latest Quark-Meson Coupling Model
Pierre A. M. Guichon; Anthony W. Thomas; Kazuo Tsushima
2007-12-12
The most recent development of the quark-meson coupling (QMC) model, in which the effect of the mean scalar field in-medium on the hyperfine interaction is also included self-consistently, is used to compute the properties of finite hypernuclei. The calculations for $\\Lambda$ and $\\Xi$ hypernuclei are of comparable quality to earlier QMC results without the additional parameter needed there. Even more significantly, the additional repulsion associated with the increased hyperfine interaction in-medium completely changes the predictions for $\\Sigma$ hypernuclei. Whereas in the earlier work they were bound by an amount similar to $\\Lambda$ hypernuclei, here they are unbound, in qualitative agreement with the experimental absence of such states. The equivalent non-relativistic potential felt by the $\\Sigma$ is repulsive inside the nuclear interior and weakly attractive in the nuclear surface, as suggested by the analysis of $\\Sigma$-atoms.
Multi-Scale Coupling in Ocean and Climate Modeling
Zhengyu Liu, Leslie Smith
2009-08-14
We have made significant progress on several projects aimed at understanding multi-scale dynamics in geophysical flows. Large-scale flows in the atmosphere and ocean are influenced by stable density stratification and rotation. The presence of stratification and rotation has important consequences through (i) the conservation of potential vorticity q = {omega} {center_dot} {del} {rho}, where {omega} is the total vorticity and {rho} is the density, and (ii) the existence of waves that affect the redistribution of energy from a given disturbance to the flow. Our research is centered on quantifying the effects of potential vorticity conservation and of wave interactions for the coupling of disparate time and space scales in the oceans and the atmosphere. Ultimately we expect the work to help improve predictive capabilities of atmosphere, ocean and climate modelers. The main findings of our research projects are described.
Nuclear pasta phases within the quark-meson coupling model
NASA Astrophysics Data System (ADS)
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.
A nonlinear coupled soil moisture-vegetation model
NASA Astrophysics Data System (ADS)
Liu, Shikuo; Liu, Shida; Fu, Zuntao; Sun, Lan
2005-06-01
Based on the physical analysis that the soil moisture and vegetation depend mainly on the precipitation and evaporation as well as the growth, decay and consumption of vegetation a nonlinear dynamic coupled system of soil moisture-vegetation is established. Using this model, the stabilities of the steady states of vegetation are analyzed. This paper focuses on the research of the vegetation catastrophe point which represents the transition between aridness and wetness to a great extent. It is shown that the catastrophe point of steady states of vegetation depends mainly on the rainfall P and saturation value v0, which is selected to balance the growth and decay of vegetation. In addition, when the consumption of vegetation remains constant, the analytic solution of the vegetation equation is obtained.
ERIC Educational Resources Information Center
Butner, Jonathan; Amazeen, Polemnia G.; Mulvey, Genna M.
2005-01-01
The authors present a dynamical multilevel model that captures changes over time in the bidirectional, potentially asymmetric influence of 2 cyclical processes. S. M. Boker and J. Graham's (1998) differential structural equation modeling approach was expanded to the case of a nonlinear coupled oscillator that is common in bimanual coordination…
New model of inflation with nonminimal derivative coupling of standard model Higgs boson to gravity.
Germani, Cristiano; Kehagias, Alex
2010-07-02
In this Letter we show that there is a unique nonminimal derivative coupling of the standard model Higgs boson to gravity such that it propagates no more degrees of freedom than general relativity sourced by a scalar field, reproduces a successful inflating background within the standard model Higgs parameters, and finally does not suffer from dangerous quantum corrections.
Stepwise calibration procedure for regional coupled hydrological-hydrogeological models
NASA Astrophysics Data System (ADS)
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
Lithosphere-Atmosphere-Ionosphere Coupling model: Fundamentals and recent developments
NASA Astrophysics Data System (ADS)
Pulinets, S. A.; Ouzounov, D.
2007-05-01
Recent theoretical and experimental studies within the frame of Lithosphere-Atmosphere-Ionosphere Coupling model (LAIC) permitted to generalize a common conception of different kinds of specific variations of geochemical, atmospheric, electromagnetic and ionospheric parameters observed before strong earthquakes. The long history of this conception (starting in 1990) and the several existing updates are mostly connected with its interdisciplinary character. LAIC is based on two simple but fundamental facts: 1) specific variations (usually increase) of radon emanation have place for every earthquake; 2) increased emanation of radon from the Earth's crust in the vicinity of active tectonic faults before an earthquake take place within the earthquake preparation area estimated by Dobrovolsky. Air ionization by radon takes place over the large territories and has a strong effect on the following processes in the atmospheric boundary layer: (1)formation of the large ion clusters due to water molecules attachment to ions; (2) latent heat release; (3) changing of boundary layer electric conductivity; (3) upward convective flux, generation of anomalous electric field; (4) air temperature increase and drop of relative humidity and (5) specific shape clouds formation. Variations of atmospheric electricity stimulated by ionization process induce variations in the ionosphere trough the global electric circuit. The simultaneous co-existence of several processes manifesting this coupling explains the variety of observed phenomena and enhances the reliability of detecting the future seismogenic signals. Interactive model improvement through data fusion using the data of satellite and ground based monitoring for the major recent earthquakes revealed new aspects of energy conversion from chemical reactions up to thermodynamics and electrodynamics.
Fully Coupled Well Models for Fluid Injection and Production
White, Mark D.; Bacon, Diana H.; White, Signe K.; Zhang, Z. F.
2013-08-05
these equations varies from zero coupling to full coupling. In this paper we describe a fully coupled solution approach for well model that allows for a flexible well trajectory and screened interval within a structured hexahedral computational grid. In this scheme the nonlinear well equations have been fully integrated into the Jacobian matrix for the reservoir conservation equations, minimizing the matrix bandwidth.
This study demonstrates the value of a coupled chemical transport modeling system for investigating groundwater nitrate contamination responses associated with nitrogen (N) fertilizer application and increased corn production. The coupled Community Multiscale Air Quality Bidirect...
This study demonstrates the value of a coupled chemical transport modeling system for investigating groundwater nitrate contamination responses associated with nitrogen (N) fertilizer application and increased corn production. The coupled Community Multiscale Air Quality Bidirect...
Phase-model analysis of coupled neuronal oscillators with multiple connections
NASA Astrophysics Data System (ADS)
Hwang, Dong-Uk; Lee, Sang-Gui; Han, Seung Kee; Kook, Hyungtae
2006-09-01
Synchronization of the coupled neuronal oscillators with multiple connections of different coupling nature is analyzed using the phase-model reduction method. Each coupling connection contributes to the dynamic behavior of the system in a complex nonlinear fashion. In the phase-model scheme, the contribution of the individual connections can be separated in terms of the effective coupling functions associated with each connection and a linear superposition of them provides the total effective coupling of the coupled system. The case of multiple connections with various conduction time delays is also examined, which is shown to be capable of promoting synchronization over an ensemble of spatially distributed neuronal oscillators in an efficient way.
Asynchronously Coupled Models of Ice Loss from Airless Planetary Bodies
NASA Astrophysics Data System (ADS)
Schorghofer, N.
2016-12-01
Ice is found near the surface of dwarf planet Ceres, in some main belt asteroids, and perhaps in NEOs that will be explored or even mined in future. The simple but important question of how fast ice is lost from airless bodies can present computational challenges. The thermal cycle on the surface repeats on much shorter time-scales than ice retreats; one process acts on the time-scale of hours, the other over billions of years. This multi-scale situation is addressed with asynchronous coupling, where models with different time steps are woven together. The sharp contrast at the retreating ice table is dealt with with explicit interface tracking. For Ceres, which is covered with a thermally insulating dust mantle, desiccation rates are orders of magnitude slower than had been calculated with simpler models. More model challenges remain: The role of impact devolatization and the time-scale for complete desiccation of an asteroid. I will also share my experience with code distribution using GitHub and Zenodo.
Coupled transport/hyperelastic model for nastic materials
NASA Astrophysics Data System (ADS)
Homison, Chris; Weiland, Lisa M.
2006-03-01
Nastic materials are high energy density active materials that mimic processes used in the plant kingdom to produce large deformations through the conversion of chemical energy. These materials utilize the controlled transport of charge and fluid across a selectively-permeable membrane to achieve bulk deformation in a process referred to in the plant kingdom as nastic movements. The nastic material being developed consists of synthetic membranes containing biological ion pumps, ion channels, and ion exchangers surrounding fluid-filled cavities embedded within a polymer matrix. In this paper the formulation of a biological transport model and its coupling with a hyperelastic finite element model of the polymer matrix is discussed. The transport model includes contributions from ion pumps, ion exchangers, and solvent flux. This work will form the basis for a feedback loop in material synthesis efforts. The goal of these studies is to determine the relative importance of the various parameters associated with both the polymer matrix and the biological transport components.
Ising models of strongly coupled biological networks with multivariate interactions
NASA Astrophysics Data System (ADS)
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.
A simple coupled model of tropical Atlantic decadal climate variability
NASA Astrophysics Data System (ADS)
Kushnir, Yochanan; Seager, Richard; Miller, Jennifer; Chiang, John C. H.
2002-12-01
A linear, zonally averaged model of the interaction between the tropical Atlantic (TA) atmosphere and ocean is presented. A balance between evaporation and meridional heat advection in the mixed layer determines the sea surface temperature tendency. The atmosphere is a fixed-depth, sub-cloud layer in which the specific humidity anomaly is determined by a steady-state balance between evaporation, meridional advection, and a parameterized humidity exchange with the free atmosphere. When the model is integrated, forced with observed surface wind anomalies from 1965 to the present, its simulation of the observed sea surface temperature (SST) is realistic and comparable to a simulation with a full ocean GCM. A statistical representation of surface winds and their relationship to the SST gradient across the equator is used to formulate and test a coupled model of their regional variability. Forced on both sides of the equator, in the trade-wind regions, with ``white-noise'' windspeed perturbations, the SST-wind relationship in the near-equatorial region feeds back positively on existing SST anomalies and gives rise to decadal variability.
High-resolution coupled ice sheet-ocean modeling using the POPSICLES model
NASA Astrophysics Data System (ADS)
Ng, E. G.; Martin, D. F.; Asay-Davis, X.; Price, S. F.; Collins, W.
2014-12-01
It is expected that a primary driver of future change of the Antarctic ice sheet will be changes in submarine melting driven by incursions of warm ocean water into sub-ice shelf cavities. Correctly modeling this response on a continental scale will require high-resolution modeling of the coupled ice-ocean system. We describe the computational and modeling challenges in our simulations of the full Southern Ocean coupled to a continental-scale Antarctic ice sheet model at unprecedented spatial resolutions (0.1 degree for the ocean model and adaptive mesh refinement down to 500m in the ice sheet model). The POPSICLES model couples the POP2x ocean model, a modified version of the Parallel Ocean Program (Smith and Gent, 2002), with the BISICLES ice-sheet model (Cornford et al., 2012) using a synchronous offline-coupling scheme. Part of the PISCEES SciDAC project and built on the Chombo framework, BISICLES makes use of adaptive mesh refinement to fully resolve dynamically-important regions like grounding lines and employs a momentum balance similar to the vertically-integrated formulation of Schoof and Hindmarsh (2009). Results of BISICLES simulations have compared favorably to comparable simulations with a Stokes momentum balance in both idealized tests like MISMIP3D (Pattyn et al., 2013) and realistic configurations (Favier et al. 2014). POP2x includes sub-ice-shelf circulation using partial top cells (Losch, 2008) and boundary layer physics following Holland and Jenkins (1999), Jenkins (2001), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-ocean test cases (e.g., ISOMIP; Losch, 2008) and other continental-scale simulations and melt-rate observations (Kimura et al., 2013; Rignot et al., 2013). For the POPSICLES Antarctic-Southern Ocean simulations, ice sheet and ocean models communicate at one-month coupling intervals.
NASA Astrophysics Data System (ADS)
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
2014-10-31
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.
On coupling fluid plasma and kinetic neutral physics models
Joseph, I.; Rensink, M. E.; Stotler, D. P.; ...
2017-03-01
The coupled fluid plasma and kinetic neutral physics equations are analyzed through theory and simulation of benchmark cases. It is shown that coupling methods that do not treat the coupling rates implicitly are restricted to short time steps for stability. Fast charge exchange, ionization and recombination coupling rates exist, even after constraining the solution by requiring that the neutrals are at equilibrium. For explicit coupling, the present implementation of Monte Carlo correlated sampling techniques does not allow for complete convergence in slab geometry. For the benchmark case, residuals decay with particle number and increase with grid size, indicating that theymore » scale in a manner that is similar to the theoretical prediction for nonlinear bias error. Progress is reported on implementation of a fully implicit Jacobian-free Newton–Krylov coupling scheme. The present block Jacobi preconditioning method is still sensitive to time step and methods that better precondition the coupled system are under investigation.« less
A Tightly Coupled Non-Equilibrium Magneto-Hydrodynamic Model for Inductively Coupled RF Plasmas
2016-02-29
conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical...by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions...flow-field and electromagnetic phenomena inside an ICP torch requires, in theory, the coupled solution of the Navier-Stokes and the Maxwell equations
Coupling Radar Rainfall to Hydrological Models for Water Abstraction Management
NASA Astrophysics Data System (ADS)
Asfaw, Alemayehu; Shucksmith, James; Smith, Andrea; MacDonald, Ken
2015-04-01
The impacts of climate change and growing water use are likely to put considerable pressure on water resources and the environment. In the UK, a reform to surface water abstraction policy has recently been proposed which aims to increase the efficiency of using available water resources whilst minimising impacts on the aquatic environment. Key aspects to this reform include the consideration of dynamic rather than static abstraction licensing as well as introducing water trading concepts. Dynamic licensing will permit varying levels of abstraction dependent on environmental conditions (i.e. river flow and quality). The practical implementation of an effective dynamic abstraction strategy requires suitable flow forecasting techniques to inform abstraction asset management. Potentially the predicted availability of water resources within a catchment can be coupled to predicted demand and current storage to inform a cost effective water resource management strategy which minimises environmental impacts. The aim of this work is to use a historical analysis of UK case study catchment to compare potential water resource availability using modelled dynamic abstraction scenario informed by a flow forecasting model, against observed abstraction under a conventional abstraction regime. The work also demonstrates the impacts of modelling uncertainties on the accuracy of predicted water availability over range of forecast lead times. The study utilised a conceptual rainfall-runoff model PDM - Probability-Distributed Model developed by Centre for Ecology & Hydrology - set up in the Dove River catchment (UK) using 1km2 resolution radar rainfall as inputs and 15 min resolution gauged flow data for calibration and validation. Data assimilation procedures are implemented to improve flow predictions using observed flow data. Uncertainties in the radar rainfall data used in the model are quantified using artificial statistical error model described by Gaussian distribution and
Coupling a geodynamic seismic cycling model to rupture dynamic simulations
NASA Astrophysics Data System (ADS)
Gabriel, Alice; van Dinther, Ylona
2014-05-01
The relevance and results of dynamic rupture scenarios are implicitly linked to the geometry and pre-existing stress and strength state on a fault. The absolute stresses stored along faults during interseismic periods, are largely unquantifiable. They are, however, pivotal in defining coseismic rupture styles, near-field ground motion, and macroscopic source properties (Gabriel et al., 2012). Obtaining these in a physically consistent manner requires seismic cycling models, which directly couple long-term deformation processes (over 1000 year periods), the self-consistent development of faults, and the resulting dynamic ruptures. One promising approach to study seismic cycling enables both the generation of spontaneous fault geometries and the development of thermo-mechanically consistent fault stresses. This seismo-thermo-mechanical model has been developed using a methodology similar to that employed to study long-term lithospheric deformation (van Dinther et al., 2013a,b, using I2ELVIS of Gerya and Yuen, 2007). We will innovatively include the absolute stress and strength values along physically consistent evolving non-finite fault zones (regions of strain accumulation) from the geodynamic model into dynamic rupture simulations as an initial condition. The dynamic rupture simulations will be performed using SeisSol, an arbitrary high-order derivative Discontinuous Galerkin (ADER-DG) scheme (Pelties et al., 2012). The dynamic rupture models are able to incorporate the large degree of fault geometry complexity arising in naturally evolving geodynamic models. We focus on subduction zone settings with and without a splay fault. Due to the novelty of the coupling, we first focus on methodological challenges, e.g. the synchronization of both methods regarding the nucleation of events, the localization of fault planes, and the incorporation of similar frictional constitutive relations. We then study the importance of physically consistent fault stress, strength, and
Ocean-Atmosphere State Estimation and Targeted Observing using Coupled Model Ensembles
2013-09-30
1 Ocean-Atmosphere State Estimation and Targeted Observing using Coupled Model Ensembles Craig H. Bishop, PI Naval Research Laboratory...Targeted Observing using Coupled Model Ensembles 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...forecast error covariance model for this coupled system is based solely on ensemble covariances because the pre-existing covariance model does not
Acoustic Modeling Using a Three-Dimensional Coupled-Mode Model
2012-09-30
the 3D coupled-mode solution can also be observed in the semi-analytic solution by the wider shadow behind the seamount and by the interference...propagation around a shallow-water seamount , (2) the addition of a 3D rough sea surface in the model with comparison to solution calculated with a 3D...Propagation around a conical seamount The 3D coupled-mode model described above is applied to calculate propagation around a conical seamount in shallow
A coupled geomorphic and ecological model of tidal marsh evolution.
Kirwan, Matthew L; Murray, A Brad
2007-04-10
The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat.
A Coupled THMC model of FEBEX mock-up test
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.
Finite Nuclei in the Quark-Meson Coupling Model.
Stone, J R; Guichon, P A M; Reinhard, P G; Thomas, A W
2016-03-04
We report the first use of the effective quark-meson coupling (QMC) energy density functional (EDF), derived from a quark model of hadron structure, to study a broad range of ground state properties of even-even nuclei across the periodic table in the nonrelativistic Hartree-Fock+BCS framework. The novelty of the QMC model is that the nuclear medium effects are treated through modification of the internal structure of the nucleon. The density dependence is microscopically derived and the spin-orbit term arises naturally. The QMC EDF depends on a single set of four adjustable parameters having a clear physics basis. When applied to diverse ground state data the QMC EDF already produces, in its present simple form, overall agreement with experiment of a quality comparable to a representative Skyrme EDF. There exist, however, multiple Skyrme parameter sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF set of fewer parameters, derived in this work, is not open to such variation, chosen set being applied, without adjustment, to both the properties of finite nuclei and nuclear matter.
Finite Nuclei in the Quark-Meson Coupling Model
NASA Astrophysics Data System (ADS)
Stone, J. R.; Guichon, P. A. M.; Reinhard, P. G.; Thomas, A. W.
2016-03-01
We report the first use of the effective quark-meson coupling (QMC) energy density functional (EDF), derived from a quark model of hadron structure, to study a broad range of ground state properties of even-even nuclei across the periodic table in the nonrelativistic Hartree-Fock+BCS framework. The novelty of the QMC model is that the nuclear medium effects are treated through modification of the internal structure of the nucleon. The density dependence is microscopically derived and the spin-orbit term arises naturally. The QMC EDF depends on a single set of four adjustable parameters having a clear physics basis. When applied to diverse ground state data the QMC EDF already produces, in its present simple form, overall agreement with experiment of a quality comparable to a representative Skyrme EDF. There exist, however, multiple Skyrme parameter sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF set of fewer parameters, derived in this work, is not open to such variation, chosen set being applied, without adjustment, to both the properties of finite nuclei and nuclear matter.
A coupled geomorphic and ecological model of tidal marsh evolution
Kirwan, Matthew L.; Murray, A. Brad
2007-01-01
The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat. PMID:17389384
Spin foam models of matter coupled to gravity
NASA Astrophysics Data System (ADS)
Mikovic, A.
2002-05-01
We construct a class of spin foam models describing matter coupled to gravity, such that the gravitational sector is described by the unitary irreducible representations of the appropriate symmetry group, while the matter sector is described by the finite-dimensional irreducible representations of that group. The corresponding spin foam amplitudes in the four-dimensional gravity case are expressed in terms of the spin network amplitudes for pentagrams with additional external and internal matter edges. We also give a quantum field theory formulation of the model, where the matter degrees of freedom are described by spin network fields carrying the indices from the appropriate group representation. In the non-topological Lorentzian gravity case, we argue that the matter representations should be appropriate SO(3) or SO(2) representations contained in a given Lorentz matter representation, depending on whether one wants to describe a massive or a massless matter field. The corresponding spin network amplitudes are given as multiple integrals of propagators which are matrix spherical functions.
The effective damping approach to design a dynamic vibration absorber using Coriolis force
NASA Astrophysics Data System (ADS)
Viet, L. D.; Anh, N. D.; Matsuhisa, H.
2011-04-01
In this paper, the vibration reduction of a pendulum structure with dynamic vibration absorber (DVA) using Coriolis force is investigated. When the pendulum structure is subjected to a single harmonic excitation, the effective damping of Coriolis force is used with the second-order approximations to obtain the closed forms of optimal parameters of the DVA. The closed forms obtained show that the natural frequency of the absorber should be tuned to twice that of the pendulum. The closed forms of optimal parameters are verified by numerical optimization. The modified forms of optimal parameters are proposed to be used in case of general excitation. Base on this modified form, the design procedure is demonstrated by the numerical calculation of the free vibration and wind-induced vibration of a ropeway gondola.
'Coriolis resonance' within a rotating duct. [flow induced vibrations in centrifugal compressors
NASA Technical Reports Server (NTRS)
Kurosaka, M.; Caruthers, J. E.
1982-01-01
An investigation of the unsteady disturbances of a fixed frequency within a radial duct rotating at a set speed is presented. The flow is assumed to be compressible, inviscid, and of a fluid which is a perfect gas. Equations are developed for the steady and the unsteady parts of the flow in cylindrical coordinates. The unsteady disturbances are expressed by Fourier decomposition in angular position, distance into the duct, and in time. It is found that a resonance is possible when the frequency of flow disturbances is twice the shaft-rotation frequency, considering only the radial and tangential disturbances and not the radial and circumferential disturbances. The particular point at which the resonance occurs indicates the occurrence is due to the Coriolis force, which is only present in the radial and tangential directions. It is noted that the Coriolis force can only be present in open-ended ducts, such as those found in centrifugal compressors.
'Coriolis resonance' within a rotating duct. [flow induced vibrations in centrifugal compressors
NASA Technical Reports Server (NTRS)
Kurosaka, M.; Caruthers, J. E.
1982-01-01
An investigation of the unsteady disturbances of a fixed frequency within a radial duct rotating at a set speed is presented. The flow is assumed to be compressible, inviscid, and of a fluid which is a perfect gas. Equations are developed for the steady and the unsteady parts of the flow in cylindrical coordinates. The unsteady disturbances are expressed by Fourier decomposition in angular position, distance into the duct, and in time. It is found that a resonance is possible when the frequency of flow disturbances is twice the shaft-rotation frequency, considering only the radial and tangential disturbances and not the radial and circumferential disturbances. The particular point at which the resonance occurs indicates the occurrence is due to the Coriolis force, which is only present in the radial and tangential directions. It is noted that the Coriolis force can only be present in open-ended ducts, such as those found in centrifugal compressors.
Flow shear stabilization of rotating plasmas due to the Coriolis effect.
Haverkort, J W; de Blank, H J
2012-07-01
A radially decreasing toroidal rotation frequency can have a stabilizing effect on nonaxisymmetric magnetohydrodynamic (MHD) instabilities. We show that this is a consequence of the Coriolis effect that induces a restoring pressure gradient force when plasma is perturbed radially. In a rotating cylindrical plasma, this Coriolis-pressure effect is canceled by the centrifugal effect responsible for the magnetorotational instability. In a magnetically confined toroidal plasma, a large aspect ratio expansion shows that only half of the effect is canceled. This analytical result is confirmed by numerical computations. When the plasma rotates faster toroidally in the core than near the edge, the effect can contribute to the formation of transport barriers by stabilizing MHD instabilities.
Global coupled ocean-atmosphere general circulation models in LASG/IAP
NASA Astrophysics Data System (ADS)
Yongqiang, Yu; Xuehong, Zhang; Yufu, Guo
2004-06-01
Coupled ocean-atmospheric general circulation models are the only tools to quantitatively simulate the climate system. Since the end of the 1980s, a group of scientists in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), have been working to develop a global OGCM and a global coupled ocean-atmosphere general circulation model (CGCM). From the original flux anomaly-coupling model developed in the beginning of the 1990s to the latest directly-coupling model, LASG scientists have developed four global coupled GCMs. This study summarizes the development history of these models and describes the third and fourth coupled GCMs and selected applications. Strengths and weaknesses of these models are highlighted.
From strong to weak coupling in holographic models of thermalization
NASA Astrophysics Data System (ADS)
Grozdanov, Sašo; Kaplis, Nikolaos; Starinets, Andrei O.
2016-07-01
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 2 and R 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 /4π k 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.
Fully scalable implementation of a volume coupling scheme for the modeling of multiscale materials
NASA Astrophysics Data System (ADS)
Schlittler, Thiago Milanetto; Cottereau, Régis
2017-07-01
We present in this paper a new implementation of a multi-scale, multi-model coupling algorithm, with a proposed parallelization scheme for the construction of the coupling terms between the models. This allows one to study such problems with a fully scalable algorithm on large computer clusters, even when the models and/or the coupling have a high number of degrees of freedom. As an application example, we will consider a system composed by an homogeneous, macroscopic Elastic model and an anisotropic polycrystalline material model, with a volume coupling based on the Arlequin framework.
Coupled Mesoscale Modeling of the Atmosphere and Ocean
NASA Astrophysics Data System (ADS)
Hodur, Richard
2002-08-01
The Naval Research Laboratory (NRL) has developed the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS^TM). COAMPS is comprised of separate atmosphere and ocean data assimilation systems. The atmospheric portion of COAMPS has been in operational use at the Fleet Numerical Meteorology and Oceanography Center (FNMOC) since 1998, and it has been found to be useful for the prediction of mesoscale weather events in the coastal zone, and in areas of significant topography. A multivariate optimum interpolation (MVOI) analysis is used to construct analyses of the atmosphere using observations from radiosondes, satellites, ships, buoys, aircraft, etc.. Using these analyses, the COAMPS atmospheric model solves the nonhydrostatic form of the primitive equations using moving, multi-nested grids and sophisticated physical parameterizations for boundary layer, precipitation, and radiation. Although the original design of COAMPS was for shared-memory, vector-processor computers, NRL recently teamed with scientists at the Lawrence Livermore National Laboratory (LLNL) to adapt COAMPS for distributed-memory architecture computers. The new version of the COAMPS atmospheric model now supports distributed memory across nodes using the message-passing-interface (MPI), and shared memory across processors using OpenMP. Any arbitrary horizontal domain decomposition and number of halo points can be used for each nest. Tests have demonstrated that the atmospheric model scales to at least 200 processors. The ocean component of COAMPS uses a 3-dimensional MVOI analysis that can assimilate in-situ and remotely-sensed observations, as well as incorporate subsurface thermohaline structure through the use of the Modular Ocean Data Assimilation System (MODAS) synthetic database. The hydrostatic NRL Coastal Ocean Model (NCOM) is the COAMPS ocean model. NCOM uses a hybrid z/sigma vertical coordinate, and uses a 2-dimensional domain decomposition and MPI for use on distributed memory
NASA Technical Reports Server (NTRS)
DiZio, P.; Lackner, J. R.
2000-01-01
Reaching movements made to visual targets in a rotating room are initially deviated in path and endpoint in the direction of transient Coriolis forces generated by the motion of the arm relative to the rotating environment. With additional reaches, movements become progressively straighter and more accurate. Such adaptation can occur even in the absence of visual feedback about movement progression or terminus. Here we examined whether congenitally blind and sighted subjects without visual feedback would demonstrate adaptation to Coriolis forces when they pointed to a haptically specified target location. Subjects were tested pre-, per-, and postrotation at 10 rpm counterclockwise. Reaching to straight ahead targets prerotation, both groups exhibited slightly curved paths. Per-rotation, both groups showed large initial deviations of movement path and curvature but within 12 reaches on average had returned to prerotation curvature levels and endpoints. Postrotation, both groups showed mirror image patterns of curvature and endpoint to the per-rotation pattern. The groups did not differ significantly on any of the performance measures. These results provide compelling evidence that motor adaptation to Coriolis perturbations can be achieved on the basis of proprioceptive, somatosensory, and motor information in the complete absence of visual experience.
The Coriolis effect on mass wasting during the Rheasilvia impact on asteroid Vesta
NASA Astrophysics Data System (ADS)
Otto, K. A.; Jaumann, R.; Krohn, K.; Spahn, F.; Raymond, C. A.; Russell, C. T.
2016-12-01
We investigate the influence of the Coriolis force on mass motion related to the Rheasilvia impact on asteroid Vesta. Observations by the NASA Dawn mission revealed a pattern of curved radial ridges, which are related to Coriolis-deflected mass-wasting during the initial modification stage of the crater. Utilizing the projected curvature of the mass-wasting trajectories, we developed a method that enabled investigation of the initial mass wasting of the Rheasilvia impact by observational means. We demonstrate that the Coriolis force can strongly affect the crater formation processes on rapidly rotating objects, and we derive the material's velocities (28.9 ± 22.5 m/s), viscosities (1.5-9.0 × 106 Pa s) and coefficients of friction (0.02-0.81) during the impact modification stage. The duration of the impact modification stage could be estimated to (1.1 ± 0.5) h. By analyzing the velocity distribution with respect to the topography, we deduce that the Rheasilvia impactor hit a heterogeneous target and that the initial crater walls were significantly steeper during the modification stage.
Coriolis effect on dynamic stall in a vertical axis wind turbine
NASA Astrophysics Data System (ADS)
Tsai, Hsieh-Chen; Colonius, Tim
2013-11-01
The immersed boundary method is used to simulate the flow around a two-dimensional rotating NACA 0018 airfoil at moderate (sub-scale) Reynolds number in order to investigate separated flow occurring on a vertical-axis wind turbine (VAWT). The influence of dynamic stall on the forces is characterized as a function of tip-speed ratio. The influence of the Coriolis effect is also investigated by comparing the rotating airfoil to one undergoing a surging and pitching motion that produces an equivalent speed and angle-of-attack variation over the cycle. While the Coriolis force produces only small differences in the averaged forces, it plays an important role during dynamic stall. Due to the fact that the Coriolis force deflects the fluid and propagates the vortices differently, the wake-capturing phenomenon of the trailing edge vortex is observed in the flow around the rotating airfoil during a certain range of azimuthal angle. This wake-capturing of the trailing edge vortex leads to a large decrease in lift. However, because of the phase difference between each wake-capturing, there are only small differences in the average forces. The simulations are also compared to results from companion water-tunnel experiments at Caltech. This project is supported by the Gordon and Betty Moore Foundation.
DiZio, P; Lackner, J R
2000-10-01
Reaching movements made to visual targets in a rotating room are initially deviated in path and endpoint in the direction of transient Coriolis forces generated by the motion of the arm relative to the rotating environment. With additional reaches, movements become progressively straighter and more accurate. Such adaptation can occur even in the absence of visual feedback about movement progression or terminus. Here we examined whether congenitally blind and sighted subjects without visual feedback would demonstrate adaptation to Coriolis forces when they pointed to a haptically specified target location. Subjects were tested pre-, per-, and postrotation at 10 rpm counterclockwise. Reaching to straight ahead targets prerotation, both groups exhibited slightly curved paths. Per-rotation, both groups showed large initial deviations of movement path and curvature but within 12 reaches on average had returned to prerotation curvature levels and endpoints. Postrotation, both groups showed mirror image patterns of curvature and endpoint to the per-rotation pattern. The groups did not differ significantly on any of the performance measures. These results provide compelling evidence that motor adaptation to Coriolis perturbations can be achieved on the basis of proprioceptive, somatosensory, and motor information in the complete absence of visual experience.
Ikehata, Jun-Ichi; Shinomiya, Kazufusa; Kobayashi, Koji; Ohshima, Hisashi; Kitanaka, Susumu; Ito, Yoichiro
2004-02-06
The effect of Coriolis force on the counter-current chromatographic separation was studied using centrifugal partition chromatography (CPC) with four different two-phase solvent systems including n-hexane-acetonitrile (ACN); tert-butyl methyl ether (MtBE)-aqueous 0.1% trifluoroacetic acid (TFA) (1:1); MtBE-ACN-aqueous 0.1% TFA (2:2:3); and 12.5% (w/w) polyethylene glycol (PEG) 1000-12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise (CW) and counterclockwise column rotation. Better partition efficiencies were attained by the CW rotation in both mobile phases in all the two-phase solvent systems examined. The mathematical analysis also revealed the Coriolis force works favorably under the CW column rotation for both mobile phases. The overall results demonstrated that the Coriolis force produces substantial effects on CPC separation in both organic-aqueous and aqueous-aqueous two-phase systems.
Vibration and buckling of rotating, pretwisted, preconed beams including Coriolis effects
NASA Technical Reports Server (NTRS)
Subrahmanyam, K. B.; Kaza, K. R. V.
1985-01-01
The effects of pretwist, precone, setting angle and Coriolis forces on the vibration and buckling behavior of rotating, torsionally rigid, cantilevered beams were studied. The beam is considered to be clamped on the axis of rotation in one case, and off the axis of rotation in the other. Two methods are employed for the solution of the vibration problem: (1) one based upon a finite-difference approach using second order central differences for solution of the equations of motion, and (2) based upon the minimum of the total potential energy functional with a Ritz type of solution procedure making use of complex forms of shape functions for the dependent variables. The individual and collective effects of pretwist, precone, setting angle, thickness ratio and Coriolis forces on the natural frequencies and the buckling boundaries are presented. It is shown that the inclusion of Coriolis effects is necessary for blades of moderate to large thickness ratios while these effects are not so important for small thickness ratio blades. The possibility of buckling due to centrifugal softening terms for large values of precone and rotation is shown.
Coupled model of root water uptake, mucilage exudation and degradation
NASA Astrophysics Data System (ADS)
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
Numerical modeling of strongly-coupled dusty plasma systems
NASA Astrophysics Data System (ADS)
Vasut, John Anthony
2001-09-01
Plasma systems occur in a variety of astrophysical and laboratory environments. Often these systems contain a dust component in addition to the plasma particles. Plasmas are generally regarded as a highly disordered state of matter and dust is often seen as a contaminant to the plasma. However, in ``strongly coupled'' dusty plasmas where the electrical potential energy between the dust particles is higher than the average kinetic energy of the particles, it is possible for the system to exist in a ``liquid'' or ``crystalline'' state. The first such crystalline states were observed experimentally in 1994 and are not yet fully understood. The spacing between the particles is typically around 100 microns, allowing the individual particles to be visually observed and tracked. Several computer models have suggested that the amount of ordering present in the system should depend only upon two dimensionless parameters: the ratio of the electrical energy to the kinetic energy and the ratio of the interparticle separation to the Debye length of the plasma. These models suggest that the method in which these two parameters are reached should have no impact upon the amount of order within the system. The results of computer modeling using a tree code known as Box_Tree, which, unlike most other computer simulations, includes all interparticle interactions, shows that the method by which these parameters are reached does have an affect on the final state of the system. Box_Tree has also been used to study Mach cones caused by particles traveling through or near a dust crystal. In addition, preliminary results on the study of finite dusty plasma systems have been obtained. These results show that particles confined in a finite plasma oscillate with a frequency that depends upon particle mass and charge.
NASA Astrophysics Data System (ADS)
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.
Coupling hydrodynamic and wave propagation modeling for waveform modeling of SPE.
NASA Astrophysics Data System (ADS)
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.
Simulating urban flow and dispersion in Beijing by coupling a CFD model with the WRF model
NASA Astrophysics Data System (ADS)
Miao, Yucong; Liu, Shuhua; Chen, Bicheng; Zhang, Bihui; Wang, Shu; Li, Shuyan
2013-11-01
The airflow and dispersion of a pollutant in a complex urban area of Beijing, China, were numerically examined by coupling a Computational Fluid Dynamics (CFD) model with a mesoscale weather model. The models used were Open Source Field Operation and Manipulation (OpenFOAM) software package and Weather Research and Forecasting (WRF) model. OpenFOAM was firstly validated against wind-tunnel experiment data. Then, the WRF model was integrated for 42 h starting from 0800 LST 08 September 2009, and the coupled model was used to compute the flow fields at 1000 LST and 1400 LST 09 September 2009. During the WRF-simulated period, a high pressure system was dominant over the Beijing area. The WRF-simulated local circulations were characterized by mountain valley winds, which matched well with observations. Results from the coupled model simulation demonstrated that the airflows around actual buildings were quite different from the ambient wind on the boundary provided by the WRF model, and the pollutant dispersion pattern was complicated under the influence of buildings. A higher concentration level of the pollutant near the surface was found in both the step-down and step-up notches, but the reason for this higher level in each configurations was different: in the former, it was caused by weaker vertical flow, while in the latter it was caused by a downward-shifted vortex. Overall, the results of this study suggest that the coupled WRF-OpenFOAM model is an important tool that can be used for studying and predicting urban flow and dispersions in densely built-up areas.
A coupled DEM-CFD method for impulse wave modelling
NASA Astrophysics Data System (ADS)
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
Three-dimensional model of magnetized capacitively coupled plasmas
NASA Astrophysics Data System (ADS)
Rauf, Shahid; Kenney, Jason; Collins, Ken
2009-05-01
A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O2) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the E ×B drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the E ×B drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the E ×B drift. The E ×B drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the E ×B drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O2 plasma, the overall plasma is found to move in one direction due to the E ×B drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the E ×B drift direction.
Film rupture in the diffuse interface model coupled to hydrodynamics.
Thiele, U; Velarde, M G; Neuffer, K; Pomeau, Y
2001-09-01
The process of dewetting of a thin liquid film is usually described using a long-wave approximation yielding a single evolution equation for the film thickness. This equation incorporates an additional pressure term-the disjoining pressure-accounting for the molecular forces. Recently a disjoining pressure was derived coupling hydrodynamics to the diffuse interface model [L. M. Pismen and Y. Pomeau, Phys. Rev. E 62, 2480 (2000)]. Using the resulting evolution equation as a generic example for the evolution of unstable thin films, we examine the thickness ranges for linear instability and metastability for flat films, the families of stationary periodic and localized solutions, and their linear stability. The results are compared to simulations of the nonlinear time evolution. From this we conclude that, within the linearly unstable thickness range, there exists a well defined subrange where finite perturbations are crucial for the time evolution and the resulting structures. In the remainder of the linearly unstable thickness range the resulting structures are controlled by the fastest flat film mode assumed up to now for the entire linearly unstable thickness range. Finally, the implications for other forms of disjoining pressure in dewetting and for spinodal decomposition are discussed.
Singular Vector and ENSO Predictability in a Hybrid Coupled Model
NASA Astrophysics Data System (ADS)
Zhou, Xiaobing; Tang, Youmin
2010-05-01
In this study, singular vector (SV) and retrospective ENSO (El Niño and Southern Oscillation) predictions were performed respectively for the period from 1876 to 2000 using a hybrid coupled model. Emphasis was placed on exploring the relationship between SV and ENSO predictability. It is found that a defined Niño3 index from the first singular vector of sea surface temperature anomaly (SSTA) is highly correlated with the predicted Niño3 SSTA index of 6-month leads and that the first singular value (FSV) is positively correlated with the predictive skill. These results and findings improve our knowledge and understanding to the relationship between SV and predictability. It was thought that the fastest growth rate of errors to be inversely related to the prediction skill. The reasons why there is such a relationship between SV and realistic predictability include: (1) the strong signals of ENSO variability that favour the growth of initial uncertainties also have significant contributions to the predictability; (2) the averaged climate state of the tropical Pacific Ocean simultaneously effects both SV and predictability.
2 π production in the Giessen coupled-channels model
NASA Astrophysics Data System (ADS)
Shklyar, V.; Lenske, H.; Mosel, U.
2016-04-01
The coupled-channels Lagrangian approach underlying the Giessen model (GiM) is extended to describe the π N →π N ,2 π N scattering in the resonance energy region. As a feasibility study we investigate single- and double-pion production up to the second resonance region. The 2 π N production has been significantly improved by using the isobar approximation with σ N and π Δ (1232 ) in the intermediate state. The three-body unitarity is maintained up to an interference pattern between the isobar subchannels. The scattering amplitudes are obtained as a solution of the Bethe-Salpeter equation in the K -matrix approximation. As a first application we perform a partial-wave analysis of the π N →π N ,π0π0N reactions in the Roper resonance region. We obtain Rσ N(1440 ) =27-9+4% and Rπ Δ(1440 ) =12-3+5% for the σ N and π Δ (1232 ) decay branching ratios of N*(1440 ) , respectively. The extracted π N inelasticities and reaction amplitudes are consistent with the results from other groups.
Three-dimensional model of magnetized capacitively coupled plasmas
Rauf, Shahid; Kenney, Jason; Collins, Ken
2009-05-15
A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O{sub 2}) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the ExB drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the ExB drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the ExB drift. The ExB drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the ExB drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O{sub 2} plasma, the overall plasma is found to move in one direction due to the ExB drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the ExB drift direction.
Utility of coupling nonlinear optimization methods with numerical modeling software
Murphy, M.J.
1996-08-05
Results of using GLO (Global Local Optimizer), a general purpose nonlinear optimization software package for investigating multi-parameter problems in science and engineering is discussed. The package consists of the modular optimization control system (GLO), a graphical user interface (GLO-GUI), a pre-processor (GLO-PUT), a post-processor (GLO-GET), and nonlinear optimization software modules, GLOBAL & LOCAL. GLO is designed for controlling and easy coupling to any scientific software application. GLO runs the optimization module and scientific software application in an iterative loop. At each iteration, the optimization module defines new values for the set of parameters being optimized. GLO-PUT inserts the new parameter values into the input file of the scientific application. GLO runs the application with the new parameter values. GLO-GET determines the value of the objective function by extracting the results of the analysis and comparing to the desired result. GLO continues to run the scientific application over and over until it finds the ``best`` set of parameters by minimizing (or maximizing) the objective function. An example problem showing the optimization of material model is presented (Taylor cylinder impact test).
Gansert, Juliane; Golowasch, Jorge; Nadim, Farzan
2008-01-01
Gap junctions are known to be important for many network functions such as synchronization of activity and the generation of waves and oscillations. Gap junctions have also been proposed to be essential for the generation of early embryonic activity. We have previously shown that the amplitude of electrical signals propagating across gap-junctionally coupled passive cables is maximized at a unique diameter. This suggests that threshold-dependent signals may propagate through gap junctions for a finite range of diameters around this optimal value. Here we examine the diameter dependence of action potential propagation across model networks of dendro-dendritically coupled neurons. The neurons in these models have passive soma and dendrites and an action potential generating axon. We show that propagation of action potentials across gap junctions occurs only over a finite range of dendritic diameters and that propagation delay depends on this diameter. Additionally, in networks of gap-junctionally coupled neurons, rhythmic activity can emerge when closed loops (re-entrant paths) occur but again only for a finite range of dendrite diameters. The frequency of such rhythmic activity depends on the length of the path and the dendrite diameter. For large networks of randomly coupled neurons, we find that the re-entrant paths that underlie rhythmic activity also depend on dendrite diameter. These results underline the potential importance of dendrite diameter as a determinant of network activity in gap-junctionally coupled networks, such as network rhythms that are observed during early nervous system development. PMID:17913989
Examining the Utility of Topic Models for Linguistic Analysis of Couple Therapy
ERIC Educational Resources Information Center
Doeden, Michelle A.
2012-01-01
This study examined the basic utility of topic models, a computational linguistics model for text-based data, to the investigation of the process of couple therapy. Linguistic analysis offers an additional lens through which to examine clinical data, and the topic model is presented as a novel methodology within couple and family psychology that…
General solutions of integrable cosmological models with non-minimal coupling
NASA Astrophysics Data System (ADS)
Kamenshchik, A. Yu.; Pozdeeva, E. O.; Tronconi, A.; Venturi, G.; Vernov, S. Yu.
2017-03-01
We study the integrable model with minimally and non-minimally coupled scalar fields and the correspondence of their general solutions. Using the model with a minimally coupled scalar field and a the constant potential as an example we demonstrate the difference between the general solutions of the corresponding models in the Jordan and the Einstein frames.
Examining the Utility of Topic Models for Linguistic Analysis of Couple Therapy
ERIC Educational Resources Information Center
Doeden, Michelle A.
2012-01-01
This study examined the basic utility of topic models, a computational linguistics model for text-based data, to the investigation of the process of couple therapy. Linguistic analysis offers an additional lens through which to examine clinical data, and the topic model is presented as a novel methodology within couple and family psychology that…
Collective states of odd nuclei in a model with quadrupole-octupole degrees of freedom
Minkov, N. Drenska, S. B.; Yotov, P.; Bonatsos, D. Scheid, W.
2007-08-15
We apply the collective axial quadrupole-octupole Hamiltonian to describe the rotation-vibration motion of odd nuclei with Coriolis coupling between the even-even core and the unpaired nucleon.We consider that the core oscillates coherently with respect to the quadrupole and octupole axialdeformation variables. The coupling between the core and the unpaired nucleon provides a split paritydoublet structure of the spectrum. The formalism successfully reproduces the parity-doublet splitting in a wide range of odd-A nuclei. It provides model estimations for the third angular-momentum projection K on the intrinsic symmetry axis and the related intrinsic nuclear structure.
Nonlinear interaction between underwater explosion bubble and structure based on fully coupled model
NASA Astrophysics Data System (ADS)
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
Modeling biogeochemical cycles in Chesapeake Bay with a coupled physical biological model
NASA Astrophysics Data System (ADS)
Xu, Jiangtao; Hood, Raleigh R.
2006-08-01
In this paper we describe the development and validation of a relatively simple biogeochemical model of Chesapeake Bay. This model consists of a 3-dimensional, prognostic hydrodynamic model that is coupled to an NPZD-type open ocean ecosystem model, which has been modified by adding additional compartments and parameterizations of biogeochemical processes that are important in estuarine systems. These modifications include an empirical optical model for predicting the diffuse attenuation coefficient Kd, compartments for representing oxygen and suspended sediment concentrations, and parameterizations of phosphorus limitation, denitrification, and seasonal changes in ecosystem structure and temperature effects. To show the overall performance of the coupled physical-biological model, the modeled dissolved inorganic nitrogen, phytoplankton, dissolved oxygen, total suspended solids and light attenuation coefficient in 1995 (a dry year) and 1996 (a very wet year) are examined and compared with observations obtained from the Chesapeake Bay Program. We demonstrate that this relatively simple model is capable of producing the general distribution of each field (both the mean and variability) in the main stem of the Bay. And the model is robust enough to generate reasonable results under both wet and dry conditions. Some significant discrepancies are also observed, such as overestimation of phytoplankton concentrations in shoal regions and overestimation of oxygen concentrations in deep channels, which reveal some deficiencies in the model formulation. Some potential improvements and remedies are suggested. Sensitivity studies on selected parameters are also reported.
A Replica-Coupling Approach to Disordered Pinning Models
NASA Astrophysics Data System (ADS)
Toninelli, Fabio Lucio
2008-06-01
We consider a renewal process τ = { τ 0, τ 1,...} on the integers, where the law of τ i - τ i-1 has a power-like tail P( τ i - τ i-1 = n) = n -(α+1) L( n) with α ≥ 0 and L(·) slowly varying. We then assign a random, n-dependent reward/penalty to the occurrence of the event that the site n belongs to τ. In such generality this class of problems includes, among others, (1 + d)-dimensional models of pinning of directed polymers on a one-dimensional random defect, (1 + 1)-dimensional models of wetting of disordered substrates, and the Poland-Scheraga model of DNA denaturation. By varying the average of the reward, the system undergoes a transition from a localized phase, where τ occupies a finite fraction of {mathbb{N}} to a delocalized phase, where the density of τ vanishes. In absence of disorder (i.e., if the reward is independent of n), the transition is of first order for α > 1 and of higher order for α < 1. Moreover, for α ranging from 1 to 0, the transition ranges from first to infinite order. Presence of even an arbitrarily small (but extensive) amount of disorder is known to modify the order of transition as soon as α > 1/2 [11]. In physical terms, disorder is relevant in this situation, in agreement with the heuristic Harris criterion. On the other hand, for 0 < α < 1/2 it has been proven recently by K. Alexander [2] that, if disorder is sufficiently weak, critical exponents are not modified by randomness: disorder is irrelevant. In this work, generalizing techniques which in the framework of spin glasses are known as replica coupling and interpolation, we give a new, simpler proof of the main results of [2]. Moreover, we (partially) justify a small-disorder expansion worked out in [9] for α < 1/2, showing that it provides a free energy upper bound which improves the annealed one.
Exploring coupled 4D-Var data assimilation using an idealised atmosphere-ocean model
NASA Astrophysics Data System (ADS)
Smith, Polly; Fowler, Alison; Lawless, Amos; Haines, Keith
2014-05-01
The successful application of data assimilation techniques to operational numerical weather prediction and ocean forecasting systems has led to an increased interest in their use for the initialisation of coupled atmosphere-ocean models in prediction on seasonal to decadal timescales. Coupled data assimilation presents a significant challenge but offers a long list of potential benefits including improved use of near-surface observations, reduction of initialisation shocks in coupled forecasts, and generation of a consistent system state for the initialisation of coupled forecasts across all timescales. In this work we explore some of the fundamental questions in the design of coupled data assimilation systems within the context of an idealised one-dimensional coupled atmosphere-ocean model. The system is based on the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) atmosphere model and a K-Profile Parameterisation (KKP) mixed layer ocean model developed by the National Centre for Atmospheric Science (NCAS) climate group at the University of Reading. It employs a strong constraint incremental 4D-Var scheme and is designed to enable the effective exploration of various approaches to performing coupled model data assimilation whilst avoiding many of the issues associated with more complex models. Working with this simple framework enables a greater range and quantity of experiments to be performed. Here, we will describe the development of our simplified single-column coupled atmosphere-ocean 4D-Var assimilation system and present preliminary results from a series of identical twin experiments devised to investigate and compare the behaviour and sensitivities of different coupled data assimilation methodologies. This includes comparing fully and weakly coupled assimilations with uncoupled assimilation, investigating whether coupled assimilation can eliminate or lessen initialisation shock in coupled model forecasts, and
Mathematical and Computational Modeling of Multiphysics Couplings in the Geosciences
NASA Astrophysics Data System (ADS)
Wheeler, M. F.
2004-12-01
Multiphysics couplings can happen in different ways. Aƒâ_sA,A One may have different physical processes (e.g. flow, transport, reactions) occurring within the same physical domain, or one may have different physical regimes (e.g., surface/subsurface environments, fluid/structure interactions) interacting through interfaces. We will discuss both of these types of multiphysics couplings during this presentation. Of particular interest will be the development of interpolation/projection algorithms for projecting physical quantities from one space/time grid to another, the investigation of mortar and mortar-free methods for coupling multiple physical domains, and the coupling of non-conforming and conforming finite element methods.
Modeling of the Coupled Magnetospheric and Neutral Wind Dynamos
NASA Technical Reports Server (NTRS)
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.
Coupling geodynamic with thermodynamic modelling for reconstructions of magmatic systems
NASA Astrophysics Data System (ADS)
Rummel, Lisa; Kaus, Boris J. P.; White, Richard
2016-04-01
Coupling geodynamic with petrological models is fundamental for understanding magmatic systems from the melting source in the mantle to the point of magma crystallisation in the upper crust. Most geodynamic codes use very simplified petrological models consisting of a single, fixed, chemistry. Here, we develop a method to better track the petrological evolution of the source rock and corresponding volcanic and plutonic rocks by combining a geodynamic code with a thermodynamic model for magma generation and evolution. For the geodynamic modelling a finite element code (MVEP2) solves the conservation of mass, momentum and energy equations. The thermodynamic modelling of phase equilibria in magmatic systems is performed with pMELTS for mantle-like bulk compositions. The thermodynamic dependent properties calculated by pMELTS are density, melt fraction and the composition of the liquid and solid phase in the chemical system: SiO2-TiO2-Al2O3-Fe2O3-Cr2O3-FeO-MgO-CaO-Na2O-K2O-P2O5-H2O. In order to take into account the chemical depletion of the source rock with increasing melt extraction events, calculation of phase diagrams is performed in two steps: 1) With an initial rock composition density, melt fraction as well as liquid and solid composition are computed over the full upper mantle P-T range. 2) Once the residual rock composition (equivalent to the solid composition after melt extraction) is significantly different from the initial rock composition and the melt fraction is lower than a critical value, the residual composition is used for next calculations with pMELTS. The implementation of several melt extraction events take the change in chemistry into account until the solidus is shifted to such high temperatures that the rock cannot be molten anymore under upper mantle conditions. An advantage of this approach is that we can track the change of melt chemistry with time, which can be compared with natural constraints. In the thermo-mechanical code the
Coupling giant impacts and long-term evolution models
NASA Astrophysics Data System (ADS)
Golabek, G.; Jutzi, M.; Emsenhuber, A.; Gerya, T.; Asphaug, E. I.
2015-12-01
The crustal dichotomy [1] is the dominant geological feature on planet Mars. The exogenic approach to the origin of the crustal dichotomy [2-6] assumes that the northern lowlands correspond to a giant impact basin formed after primordial crust formation. However these simulations only consider the impact phase without studying the long-term repercussions of such a collision. The endogenic approach [7], suggesting a degree-1 mantle upwelling underneath the southern highlands [8-11], relies on a high Rayleigh number and a particular viscosity profile to form a low degree convective pattern within the geological constraints for the dichotomy formation. Such vigorous convection, however, results in continuous magmatic resurfacing, destroying the initially dichotomous crustal structure in the long-term. A further option is a hybrid exogenic-endogenic approach [12-15], which proposes an impact-induced magma ocean and subsequent superplume in the southern hemisphere. However these models rely on simple scaling laws to impose the thermal effects of the collision. Here we present the first results of impact simulations performed with a SPH code [16,17] serially coupled with geodynamical computations performed using the code I3VIS [18] to improve the latter approach and test it against observations. We are exploring collisions varying the impactor velocities, impact angles and target body properties, and are gauging the sensitivity to the handoff from SPH to I3VIS. As expected, our first results indicate the formation of a transient hemispherical magma ocean in the impacted hemisphere, and the merging of the cores. We also find that impact angle and velocity have a strong effect on the post-impact temperature field [5] and on the timescale and nature of core merger.